4 - Brookhaven National Laboratory

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The new Advanced Polymers PRT on Beamline X27C: The coverfigures are simultaneous 

small- and wide-angle x-ray scattering patterns of Poly(viny1idene fluoride) (PVDF) fiber 

collected during deformation at different strains (/@:zero strain, right: 740% strain). From 

these patterns, it is seen that the application of strain not only transforms the PVDF crystal 

from an alphaform to a beta-form, but also induces microviods in the stretchedfiber. Thls 

study suggests a novel way to produce polymerfibers with nanoscale porosity. This work is 

funded by a NSF-COAL1 grant (DMR-9629825). 

I. Wu, J.M. Schultz (University of Delaware), F: Yeh, and B. Hsiao (SUNY at Stony Brook) 

DISCLAIMER 

This report was prepared as an account of work sponsored by an agency of 

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(General Energy Research)

For the period October 1, 1996 through September 30, 1997 

May 1998 

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Science Editor 

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. . 

The National Synchrotron Light Source Depar;trnent 

3 '*~ 

is' supported by the 

Office &f Basic Enerw ', Sciences 

United States.Departm.ent of Energy 

Washington, D.C. 

~ O F R H S D O C ~ * U N W W C ~ ~ 

Brookhaven National Laboratory 

Upton, New York 1 1973 

http://www.bnl.gov

INTRODUCTION 

BY THE CHAIRMAN 

Michael Hart 

ENVIRONMENT, SAFETY AND HEALTH 

William Thomlinson 

USERS' EXECUTIVE COMMITTEE 

loel D. Brock 

..................................................... ................ ............. . ...... 1-2 

UPDATE 

................................................................. 

....... 1 -4 

..................................................................................... . .... .... 1-6 

GEOLOGICAL SCIENCES ................................................................................................... 2-2 5 

INSTRUMENTATION 

AND TECHNIQUES .................................................... .... ........... . ..... . ........ 2-34 

MATERIALS SCIENCES ........................................................................................................... 2-44 

THE 1997 NSLS ANNUAL USERS' MEETING ....................................................................... 3-2 

Joel D. Brock 

THE ~MPACT OF NEW DETECTOR TECHNOLOGY ON SYNCHROTRON 

MACROMOLECULAR CRYSTALLOGRAPHY .................................................................................. 3-4 

APPLICATIONS OF EXAFS SPECTROSCOPY ................................. 3-5 

Mark R. Chance 

X-RAY COMPUTED MICROTOMOGRAPHY: APPLICATIONS 8 TECHNIQUES ................................ 3-6 

Betsy Do wd 

INELASTIC 

AND RESONANT INELASTIC X-RAY SCATERING ...................................................... 3-7 

Chi-Chang Kao 

MATERIALS CHARACTERIZATION WITH HARD AND SOFT X-RAY REFLECTIVITY ........................ 3-8 

Michael Toney

VUV MACHINE ..................................................................................................................... 4-2 

Stephen Kramer 

VUV STORAGE RING PARAMETERS ....................................................................................... 4-5 


X-RAY RING .......................................................................................................................... 4-6 

Roger Klaffky 

X-RAY STORAGE RING PARAMETERS ...................................................................................... 4-9 

Roger Klaffky 

BEAMLINE TECHNICAL IMPROVEMENTS ................................................................................. 4-10 

Roger KIaffky 

THE NSLS SOURCE DEVELOPMENT LABORATORY .................................................................. 5-2 

Erik D . Johnson 

THE ACCELERATOR TEST FACILITY (ATF) ............................................................................... 5-4 

llan Ben-Zvi 

NS LS ADVISORY COMMITTEES .............................................................................................. 6-2 

NSLS STAFF .......................................................................................................................... 6-4 

VUV BEAMLINE GUIDE ......................................................................................................... 6-7 

X-RAY BEAMLINE GUIDE ...................................................................................................... 6-11 

VUV BEAM LINE ABSTRACTS .................................................................................................. A- 1 

X-RAY BEAM LINE ABSTRACTS ................................................................................................ B- 1 

NSLS USER PUBLICATIONS .................................................................................................... C- 1 

NSLS STAFF PUBLICATIONS .................................................................................................. D- 1 

BNL FORMAL AND INFORMAL REPORTS ............................................................................... D-5

Beamline X20C: The figure at right is an example of silicide phase formation from the reaction 

of metals with silicon. Time-resolved x-ray diffraction is used to capture the formation 

sequence during rapid thermal annealing. A resistive heater encapsulated in pyrolytic boron 

nitride is used together with a linear position sensitive detector allowing for the required time 

resolution during annealing at ramp rates of up to 35" C/s. Notice that in the figure, as 

temperature is ramped from 400°C to above 1000°C, at least ten different diffraction peaks 

representing four distinct silicide phases are present in the ten degree two theta diffraction 

range. C. Lavoie and C. Cabral, Jr. (IBM Research Division, Yorktown Heights, NY).

Temp (C) 

1000 

46 

Two Theta (deg)

Michael Hart 

NSLS Chairman 

During FY 1997 Rrookhaven National Laboratory "The pnnel wns very impressed by the outstanding 

celebrated it's 50"' Anniversary and 50 years of outstanding petfirmanre of'tl~e second generntion firilities (SSRL rznd 

~chievement under the management of Associated NSLS), by the number ofirsers thg, serve well, by their ability 

Universities. Inc. The National Synchrotron Light Source m renew and improve themselves, by their ability to continue 

md its ~lsers' research record are part of that history and, cvtting-e~iye research even tj~ough the storage rings themselves 

appropriately, since research with light from synchrotron rzre not the most advanced, bv their commitment to education, 

rxiiation h~s matured, the scene was set for a maior ,zizd by their czbilities to engrzge rwru users and clddress new 

national review of the D.O.E. synchrotron radi;ltion problems. Given the outstclnditz~q track recordnnd clear vision 

~xovision. 

~/c,rtrotlstrcItL'ntl hy t/JlYc' /,'~i.ilities. t/~e prznel qects t/~ese 

In the sccond wcck of the I:iscal l;..lr the chxgc /;lcilities to onti ti nu^ to t/)t.ilg~ s~~iet~t~f;rd~ in cz cost-cfectit~e 

\V;IS o~~tlincd ; I I included ~ I>orh the cspccrcci items and I N ~III JILY T/~ese centers ~ IIY tlt~tio ~tll resources nnd t/~qv should 

the tlncxpcctcd "What would l>c the consequences of the /w ~ ~~/L,LII~~I~L~~~~~JIL/~L/, 

~r/)~qr~~dedtirtd modernized it1 cz timely 

hh~~tdo\vn of one or ~iiore of the four 1~Ol~l1~13 /,is/)ion to wrue b~tter t/~c ~~r~tiorlrll t~eeds. " 

hynchrorron light sources?" A challcngc indeed! Within 

,I year the process had run to completion under the 

, - I he path to at least another decade of outstanding 

(:hairmanship of Dr. Ilobcrt Birgcncau \vith a resounding rcscxch ut NSLS was clcrirly laid out with appropriate 

chr message; 

filnding recommendations which were accepted in full 

by the Basic Energy Sciences Advisory Committee 

(BESAC). 

In addition to formal meetings and the collection 

of statistics, the review included a visit to NSLS at which 

staff and uscrs h;~d a well-used opportunity to convincc 

the pancl ofthc strength ofour program. By the end of 

FY 1097 NSLS had welcomed its 7000"' user. For each 

of the last five years more than 2200 uscrs came to the 

light source: ;dmost 800 new users in each year. 'The 

strength of their programs in terms of quality iund q~~arltity 

was made clear in the presentations to the pancl and by 

the k t ofovcr 4000 pul>lic;~tions in ;limost ,250 different 

Journ;lls during the I OWs alone. As the bar chart shows, 

within dmost constant tot;~l numbers the NSLS user 

community is not static hut represents a thriving and 

evolving population. 'The pioneers of research with 

synchrotron radiation from the physical sciences continue 

in steady numbers but new communities in the biological 

and environmental sciences are growing rapidly with a 

four to five year doubling time. In FY 1997 one third of 

our users were under the age of 30 and less than one 

third were over 40. Although about one half come from 

US ~miversities the whole of the national and international 

scientific and technological enterprise is strongly 

represented, ;IS the pic-chart shows.

An outstanding year was overshadowed by the unprecedented early termination of the Associated Universities 

contract to manage the Brookhaven National Laboratory. The details are well known and some of these are outlined 

later in this Activity Report (page 1-4) . On 1 March 1998 Brookhaven Science Associates will take responsibility for 

setting the standards for the second half century of research at Brookhaven. II 

For. L 

NSLS Users by Institution Type 

US C o r m 

- Foreign ~ n d 

S Univ 

Inst. Tvpe # Users 

US Univ 1163 

US Other 5 8 

US Lab 369 

US Govt 113 

US Corp 240 

Foreign Univ 258 

Foreign Other 76 

Foreign 

Lab/Govt/Corp 43 

Total Users 

for FY 1997: 2320 

NSLS Users by Field of Research 

Fiscal Year 

Chemical Sciences Materials Sciences 

Life Sciences Geological Sciences 

0 Applied Science & Engineering Optical, Nuclear, General Physics 

Percent 

50.1 

2.5 

15.9 

4.9 

10.3 

11.1 

3.3 

1.9 

100.0

William Thomlinson 

Associate Chairman for ES&H 

There is no doubt about this past fiscal year bcing Gmiir, resulted in the NSLS rccciving vcry good rcvicws. 

one of great accomplishments for the NSLS. But it has Our Tier I safcty asscssmcnts proccdurcs and thc tracking 

also been a year largely overshadowed by the chaos of findings developed by John Aloi wcrc highlighted as 

surrounding all of BNL with respect to management and outstanding procedures. In addition, our appointrncnt 

ESH issues. Everyone knows that the conlbination of of Mike Buckley as our Conduct of Operations 

the discovery of the tritium plume from the spent fuel Coordinator was- timely and cffectivc. TIIC steady, 

pool at the HFBR and the extremely negative Integrated professional safety opcrations dircctcd by Tom 13ickinson 

Safety Management Evaluation of BNL lead to the current were clearly one of the strengths rccognizcd hy the 

situation. By the time this is published, BNL will have a assessment team. Somewcakncsses in work planning wcre 

new contractor and hopefully some measure of stability pointcd out in our experimental reviews (corrcctcd with 

and reason will be back in vogue. One result is that ESH our new expcrimcnt Safcty Approval Form). Of coursc, 

at BNL, and the NSLS in this ycar thc good news 

particular, have taken on f was ovcrshadowcd by 

a heightened level of At the NSLS, we haveparticipated in all of the An clcctricd 

priority. At the NSLS, we 

participated in of 

ESH both 

on-going and new, and 

have overall been 

extremely pleased to find 

that our safety programs . 

ESH activities, both on-going &,,d trew, a7,d safcty incidcn t at the 

have overall been extreme4 pleased to Jind that 

NSLS involving a Plant 

Engineering employee 

our safety programs are solid. Zn general, we 

was onc of thc incidents 

already meet all new stanhlzis and havepet$med 

pointed at by the ISME 

in an exemplrzry fashion throughout all reviews. 

team in thcir cxtrcmcly 

A negative report. At tlic 

are solid. In general, we 

NSLS, wc fclt good 

already meet all new standards and have performed in an about how we fired in thc evaluation and have already 

exemplary fashion throughout all reviews.The coming acted on correcting those legitimate wcnkncsscs found 

year will clearly be spent adjusting to new requirements during the review. 

and completing existing initiatives. 

As a rcsult of thc ISME rcport and thc canccll;~tion 

The year started with an in-depth ESH Self- of thc AUI contract, all of BNI, turned its attcntion to 

assessment. Our dedicated team of NSLS personnel ESH and managcmcnt issucs. Directly affecting thc NS1.S 

studied key areas such as Training, ALARA, ESH opcrations has been a revision of the work planning for 

communications, Quality Assurance and Conduct of expcrimcnts at BNI,. To our credit, we wcrc Inrgcly 

Operations. A list of findings was developed and exempt from that process sincc it was clear that we alrcndy 

prioritized. Our formal report was made to the BNL arc doing most ofwhat is rcquircd. In fkt, our review of 

Directorate and accepted. Some of the findings have been the final standard developed shows that we have only had 

resolved, but we have a ways to go on others. Thc cffort to forn~ally designate Andrcw Ackcrman as our 

is continuing, but has clearly been hampered by the Expcrimcnt Rcview Coordinator and givc somc 

intense involvement that we have had to have with issucs committee responsibility to our existing ESH Committee 

which have arisen this year. In particular, we had to to be fully con~pliant. That is a clcnr indication that tlic 

expend a huge anlount of resources during the DOE NSLS continues to be in thc forefront of ESH activity at 

mandated Integrated Safety Management Evaluation BNL. 

through the winter and spring. Many man-months of Based on some of the rccommcndntions in the 

effort, largely directed by our ESH Coordinator Nicholas ISME rcport, wc dccidcd to modib our Safety Approval

Form for experiments to better capture the safety measures 

being taken by the experimenters and to document the 

work control procedures that are agreed to by the NSLS 

staff and the users. At the same time, we were directly 

involved in the new Chemical Management System 

(CMS) at BNL in which all chemicals used at BNL are 

being logged into a database. At the NSLS we have a 

specific problem because of the large number of materials 

brought here by users. If ~urchased at BNL, the materials 

are automatically entered into the system and bar coded. 

However, if brought in from outside the Lab, we have a 

problem as to how to capture them in the system and 

how to assure the proper disposal. Andrew Ackerman 

worked closely with the CMS staff and made 

arrangements to exclude small quantities if brought to, 

and subsequently removed from, BNL by the user. That 

agreement makes it efficient for the users. In order to 

track those materials, however, we also had to change our 

Safety Approval Form (SAF) . 

A third issue recently arose which also impacted our 

redesign of the SAF. The DOE must receive certain data 

from the user facilities under its jurisdiction. Items such 

as user hours, institutional involvement, distribution of 

resources, etc. are necessary and must be reported. All 

facilities will uniformly report to DOE each year. At the 

NSLS, our best way to capture such information is 

through the SAF since every experiment must have one - 

whether it is performed on an NSLS or PRT beamline, 

or by General Users or PRT members. With all of these 

motivations, we worked rapidly this summer and 

produced the new, comprehensive and (we hope) more 

useful form for introduction on October 1, 1997. Our 

intent is to have a system in place by Spring of 1998 for 

electronic submissions of the SAF. That will make it very 

easy for users to submit the comprehensive information 

now required. 

In addition, many new efforts are underway which 

involve our safety staff. Upgrades at the Accelerator Test 

Facility and the Source Development Lab require new 

safety documentation. The shielding of the VLTV Ring 

and the upgraded X-Ray Ring shielding on the beamlines 

to accommodate 2.8 GeV operations are well underway. 

The latter is requiring a lot of effort by the users and the 

NSLS staff. These efforts are being carried out and 

coordinated by Andrew Ackerman, John Aloi, Tom 

Dickinson and Nick Gmiir with a lot of cooperation from 

our users and NSLS staff. 

The year has not been without problems. A worker 

at a BNL construction site was killed in an industrial 

accident. BNL was ordered to stand down for several 

days, during which the NSLS staff and users met to discuss 

the general topic of safety in the workplace. I am sure 

that this was a useful exercise based on the wide range of 

issues covered and discussed. However, the length of the 

stand down and its impact on the operations of the rings 

for users certainly detracted from its full value. 

At the NSLS we have had several reportable 

incidents due to safety issues at the facility. In evaluating 

these events, the !general theme is one of lack of individual 

responsibility or attention to good work planning and 

execution. I should note that those are fundamentals of 

Work Smart Standards which will become pervasive 

within our operations over the next year. The incidents 

include the improper use of a coffee thermos as a cryogenic 

dewar (it exploded and slightly injured two workers), a 

piece of sheet metal improperly secured during shielding 

upgrade (it slipped and nearly severed the workers thumb) 

and untrained users etching material in a hood (the 

reaction was exothermic and filled the hood and part of 

the NSLS with acid fumes). Fortunately none of these 

incidents caused severe injury, but the potential was there 

in each case. 

The NSLS cannot be responsible for training and 

behavior before a person comes to the facility and we 

cannot police everyone all the time. Users and staff must 

realize that their safety and that of their co-workers depend 

on their own behavior, training, work planning and good 

execution. 

As the new year develops and the NSLS learns what 

measures it must take to continue to improve and be 

compliant with any new regulations and standards, the 

user community will be informed and will be participants 

with us. We must continue to improve our already 

outstanding safety program, but we must remain vigilant 

to ensure that whatever changes are made are in the best 

interests of, and efficient for, our user community. .

Joel D. Brock 

Cornell University 

UEC Chair 

The purpose of the Users' Executive Committee 

(UEC) is to promote comn~unication between the user 

community and the NSLS Administration. To this end. 

the UEC conducts an annual user meeting and three 

public town meetings each year. The annual meeting 

serves several fimctions: to celebrate the scientific and 

technical accomplishments of the previous year, to obtain 

the latest news on the support of the U.S. Department 

of Energy for scientific facilities in general and the NSLS 

in particular, and to provide an opportunity to visit with 

old friends and colleagues. Although this year's annual 

mceting included six workshops and several invited 

scientific talks, the tone was dominated by the more 

political talks. The key-note address titled "Future 

Schlock by Robert Park was lively and h~~morous, poking 

fun at predictions about the future and those who nuke 

them. The Interim Director of BNL and President of 

AUI, Lyle Schwartz then made some short remarks. The 

U.S. Department of Energy was represented by the 

Associate Director of Energy Research for the Office of 

Basic Energy Sciences, Patricia M. Dehmer. In response 

to Robert Park and Lyle Schwartz, she began her remarks 

by assuring the audience that during all the upheaval 

associated with BNL's problems there has been one 

constant: "the high regard" for the NSLS, its users, and 

the quality of their science. 

The goal of the public town meetings is to provide 

a venue for discussions between users and to keep 

communication channels between the NSLS 

Administration and the users open. Typically, 

presentations by both the NSLS staff and the UEC on 

user issues are followed by opportunities for questions 

and discussion. On the day follo~ving the town meetings, 

the UEC meets with the NSLS and Brookhaven 

Laboratory staff and management to discuss relevant 

issues. The current membership of the UEC is listed in 

the caption of the accompanying photograph. Three 

general membcrs of the UEC are elected each year at the 

annual mecting and serve two year terms. Each Special 

Interest Group (SpIG) also elects (by an e-mail election) 

a representative. After the general election, the UEC elects 

one of its general members as Vice-Chair. The Vice-Chair 

is responsible for organijring the next annual meeting and 

then becomes the Chair in the following year. 

During the past year, although the UEC has dealt 

with a large number of important issucs, our focus was 

determined by the search for a new contractor to manage 

Brookhaven National 1,aboratory and by a review of all 

four of the DOE supported synchrotron facilities. We 

attempted, unsucccssfi~lly, to contribute input to thc 

Source Selection Board for use in the selection of a ncw 

contractor to manage Brookhaven National Laboratory. 

Copies of the letters sent by the UEC to the DOE? BNL 

Source Selection Board can be found on my web page - 

htt~~:II~~~~i.rnsc.corncll.cd~~I-brock. On the other hand, 

on June 25th and 26th, the users did assist with 

presentations to a review panel appointed by thc Basic 

Energy Sciences Advisory Committee (BESAC) and 

chaired by Professor Robert J. Birgeneau of M.I.T. which 

reviewed the scientific and technical programs of the 

NSLS. This panel was charged with reviewing all four of 

the DOE synchrotron facilities (the A1.S at Berkeley, the 

SSRL at Stanford, the APS at Argonne and the NSLS at 

BNL) and making recommendations for fi~turc fi~nding 

priorities. The panel was explicitly requested to consider 

the ramifications ofclosing one or more of these facilities. 

Several of the staff and users of the NS1.S were called on 

to discuss the impact synchrotron radiation has had on 

their particular field of science. It was a very impressive 

event to witness. In the short time available, leading 

experts from over a do7en distinct scicntific fields 

presented the impact science done at the NSLS has had 

on their specific field. Although I have spcnt a 

considerable amount of time working on the NSLS X- 

Ray Ring floor, I got an education about the breadth of 

the work being done at the NSLS. These talks covcrcd 

the usual areas associated with synchrotrons, materials 

science, surfacelinterface physics, n~agnetism, lithography, 

tomography, powder diffraction, macromolcc~~lar 

crystallography, infrared sources, imaging, and so on. But 

several other talks were given, such as the onc by Dr. 

Barbara Illman (USDA, U. of Madison, and new UEC

member) on the applications of synchrotron radiation to 

forest science, which illustrated the enormous potential 

of svnchrotron-based measurements to impact non- 

traditional synchrotron disciplines. The draft of the 

13irpeau panel's report (See http:/lwww-als.lbl.govlals1 

besaclindcx.html) was released early this fall and was very 

favorable towards the NSLS. Patricia Dehmer responded 

ro the report very quicklv, releasing additional funds to 

hire NSLS user support staffand to upgrade user facilities. 

Due to the increase in funding resulting from the BESAC 

panel report, the NSLS has asked the UEC for input on 

how to distribute the additional capital equipment and 

personnel support funds. Although no less difficult than 

other issues, this is a welcome departure from the far more 

frequent request to help determine where to trim. 

Looking ahead, now that a new contractor has been 

chosen to manage BNL, the UEC needs to forge a strong 

Users' Executive Committee and 

Special Interest Croup Representatives 

- - 

and positive working relationship with the new laboratory 

management. This will take some time and effort on 

both sides. 

1997 has been another year of very strong scientific 

output at the NSLS. A cursory look through the abstracts 

and publication lists in this Activity Report demonstrates 

the tremendous variety of high quality science being done 

at the NSLS. The users have come to expect excellent 

and continuously improving operations at the National 

Synchrotron Light Source. The NSLS staff have labored 

hard to ensure that the brightness, stability and reliability 

of the sources improved steadily over the years. Yet, it is 

the quality of the science performed by the users which 

ultimately determines the success or failure of the facility. 

I am quite optimistic that the NSLS will remain a vital 

facility long into the future. 

(Front, from I@ to rlght) 

Steven Whisnant (U. of So. Carolina), Malcolm Capel (NSLS-Biology), Elaine DlMasi (BNL-Physics), Joel 

Brock (Cornell U.), Eva Rothman (BNL-NSLS), and John Parlse (SUNY @ Stony Brook). 

(Back, from left to right) 

Barbara lllman (U. of Wisconsin), G. Lawrence Carr (BNL-NSLS), Michael Dudley (SUNY 8 Stony Brook), 

Peter Stephens (SUNY @ Stony Brook), tan Robinson (U. of Iliinols), D. Peter Slddons (BNL-NSLS), Peter 

Johnson (BNL-Physics), and Sanjeeva Murthy (AllledSlgnal, Inc). 

Absent from photo are Thomas Russell (U. of Massachusetts), Paul Stevens (Exxon Research and 

Engineering), Carl Zimba (MIT), Jon Levin (U. of Tennessee), and Luz Martinez-Mlranda (U. of Maryland).

Beamline X26A: A photomicrograph of a tuffaceous rock thin section (A) to which plutonium 

(Pu) had been sorbed from a solution containing predominantly Pu(V). Micro-X-ray 

fluorescence imaging isolates Fe rich (B) and Mn rich (C) inclusions. Despite predictions that Pu 

would preferentially sorb to Fe-oxides, Pu was located only as small inclusions within the Mnoxides, 

which are known to associate with smectites in the tuff (D). Micro-XANES (E) conducted 

at 10 x 15 microns with Kirkpatrick-Baez focussing mirrors indicate the average oxidation 

state is probably Pu(V) rather than the predicted reduction to Pu(lV). Given tremendous 

differences in sorption behavior between oxidation states of Pu, this information is vital for the 

prediction of fate and transport of Pu in the subsurface at nuclear waste repositories. 

M.C. Duff, D.B. Hunter (Savannah River Ecology Laboratory), D.T. Reed (Argonne National 

Laboratory), I.R. Triay, D.T. Vaniman (Los Alamos National Laboratory), and G. Shea-McCarthy 

(University of Chicago/National Synchrotron Light Source).

Asbestos Abatement 

J 

J. A. Hriljac, C. E lem, Q. Zhu, R. Sabatini, L. Petrakis (Brookhaven National 

Lab), R. Hu, an J. Block (W.R. Grace and Co.) 

The energy, technology, and environmental research 

activities which fall into the category of applied science 

sometimes directly address important problems facing 

society. Success in such projects can have an im'rnediate 

positive impact on the ~ublic, and thus garner a 

considerable amount of favorable attention from the 

general population and press. 

A striking example was announced during the Lill 

of 1007 in a press release issued by W.Il Grace and Co. 

'The col1abor;itive venture between (;race and RNL 

resulted in the development of ;I polymer foam which 

can be :ipplicd to ~isbcstos as part ofan abaccmcnt strategy, 

'The foam chemically attacks the asbestos crystal srructurc, 

leaving behind a residue of minerals which can continue 

to act as a fire retarderlinsulator. 

One important aspect leading to the s~~cccss of the 

K'. R. Grace and Co./BNL CRADA (Cooperative 

Reasearch and Devlopement Agreement) on Asbestos 

280 

1 1 ' ' ' 1 " ' ' l " " 1 ~ ~ ' ' 1 ' ~ " 

28 (degrees) 

Abatement was the ability to accurately and reliably 

determine the quantity of asbestos in treated materials. 

The current EPA-recommended method is fiber counting 

using Polarised Light Microscopy. However, at the low 

levels of asbestos that the Project Team was concerned 

with, this method was believed to be insufficiently 

accurate and alternatives were explored. 

Quantitative X-ray powder diffraction (QXRPD) 

is a well-established tool for the analysis of mixturcs of 

crystalline powders. One type of QXRPD analysis is the 

so-called ratio method, where n known quantity of an 

internal standard is mixed with chc analytc and the 

intensities of a peak from the phase of interest is compared 

with that of the added internal standard. An exact weight 

percent can then be determined by comparison to a 

calibration curve produced from carefully prepared 

standard samples. Work I d by Dr Ruizhong Hu at W. 

R. Grace and Co. focussed on the use of this method 

- 

- 

1 .O% chrysotile - 

- 

0.5% chrysotile 

0.1 % chrysotile 

Figure A-1 : 

Diffraction spectra 

around the chrysotii 

(0 0 2) peak for low 

concentration sam- 

ples of asbestos in 

alumina.

with a sealed tube X-ray source[']. A suitable method was 

developed to quantify low levels of chrysotile absbestos 

in chrysotile/gypsum/vermiculite (CGV) mixtures, a 

typical asbestos-containing material. 

One potential drawback of this method is that it 

requires a pre-treatment to remove the gypsum in order 

to allow accurate quantification at very low (< 1 %) levels. 

Proof that this did not affect the asbestos fibers (and hence 

complicate the quantification procedure) was achieved, 

in part, through the use of synchrotron X-ray powder 

diffraction at beam line X7A. Further work at X7A by 

Joe Hriljac, Cahit Eylem (then both in DAS), and Qing 

Zhu (then in Physics) extended the use of QXRPD to 

allow quantification of low levels (O.25-0.5%) of asbestos 

in the same CGV mixtures without any pre- 

treatmentL21. A plot of the diffraction data around the 

most intense peak of chrysotile in an alumina matrix is 

in Figure A- 1. H 

[I] R. Hu, J. Block, J. A. Hriljac, C. Eylem, and L. 

Petrakis, Analytical Chemistry 68, 31 12-20 (1996). 

[2] J. A. Hriljac, C. Eylem, Q. Zhu, R. Sabatini, L. 

Petrakis, R. Hu, and J. Block, Analyticd Chimica Acta 350, 

221-29 (1997). 

NEXAFS Microscopy of Polymers: Phase Separation and 

Dewetting in Polymer Thin Films and Bilayers 

H. Ade, D. A.-~inesett A. P. Smith (Dept. of Physics, NCSU), S. Ce, S. Qu, M. 

Rafailovich, S. Sokolov (Dept. of Materials Science and En r., SUNY @ Stony 

Brook), and D. Slep (Advanced Development and Researc B , Hilord Chemical 

Corp., Hauppauge, NY ) 

In many applications, the physio-mechanical 

properties of polymeric systems can be tailored by altering 

the chemical and morphological structure. In most cases, 

the polymer system of interest is not a homogeneous or 

single-component system, but is a blend, composite, or 

copolymer. Sophisticated analytical methods are required 

for their characterization. Amongst them is the recently 

developed technique of Near Edge X-ray Absorption Fine 

Structure (NEXAFS) microscopy. It has an advantage of 

about three orders of magnitude over the equivalent 

electron microscopy technique in being able to 

spectroscopically analyze and image small sample areas 

of radiation sensitive materials such as polymers[']. In 

NEXAFS microscopy, excitations of core electrons into 

unoccupied molecular orbitals provide sensitivity to a wide 

variety of chemical functionalities in polymers. This 

sensitivity complements and resembles that achieved in 

infrared (IR) spectroscopy. Although NEXAFS spectra 

are not as specific and "rich" as IR spectra, the spatial 

resolution achieved in NEXAFS microscopy is about 50 

nmL2a31, and thus much superior to that achieved in IR 

microscopy. In addition, x-ray linear dichroism 

microscopy can determine orientation of chemical 

moieties at higher spatial resolution. These inherent 

advantages of x-ray microscopy have opened up new 

avenues for the characterization of polymers. 

We will exemplify the impact of NEXAFS 

microscopy to the analysis of polymer systems by focusing 

our discussion on the characterization of phase separation 

and dewetting in polymer thin films and thin bilayers. 

Compared to bulk properties, relatively little is known 

about the properties of polymer thin films and surfaces, 

even though polymer films have considerable 

technological significance and technological applications, 

such as coatings and dielectric films. A detailed 

understanding of thin film properties and possible 

deviations from bulk properties is highly desirable and 

numerous studies on blends and bilayers have been 

undertaken in the recent past. While a variety of patterns 

that evolve during the phase separation process in polymer 

thin films have been observed, the two dimensional 

composition has never been directly determined. Often 

indirect methods, such as the use of selective solvent 

extraction for one of the phases in conjunction with AFM 

microscopy is utilized. However, the dissolution process 

can lead to ambiguities or artifacts. While qualitative 

details of the subsurface morphology might be revealed 

with electron microscopy techniques, NEXAFS 

microscopy provides quantitative equivalent thickness 

maps of each constituent polymer, which if summed 

together yield total thickness maps equivalent to AFM 

topographs. NEXAFS microscopy will thus allow for

Figure A-2: As cast thin film of 50/50 weight percent PS/PMMA 

blend imaged at (a) 289.2 eV, and (b) 285.2 eV 

Figure A-3: Same as above, but annealed for 10 min. 

Figure A-4: Same as above, but annealed for one week. 

Figure A-5: Quantitative equivalent thickness map of sample annealed 

for one week. (a) PMMA map, (b) PS map, and (c) total thickness map. 

quantitative investigation of the composition of phases 

and the dynamics of polymer phase separation. 

We investigated films composed of a 50150 weight 

percent blend of polystyrene (PS) and poly(niethyl 

methacrylate) (PMMA) spun cast onto silicon substrates 

to a thickness of 146 nm. The films wcrc then annealed 

for varying times and subsequently transferred to TEM 

grids for STXM investigation. A series of X-ray 

micrographs arc acquired in the same sample area at 

energies coinciding with characteristic NEXAFS peaks 

of the constiti~ent components. For ex;~rnplc, Figures A- 

2a, A-3a, and A-4a wcrc acquired at the C Is to n* 

carbonyl peak at 289.2 eV and emphasizes I'MMA, whilc 

Figures A-2b, A-3b, and A-4b were acquired at a photon 

energy of 285.2 eV, which is almost exclusively al,sorl,cd 

by PS. Darker regions indicate highcr x-ray ahsorption at 

the particular photon energy and yield qualitative 

information on the component composition. 'I'lic s:lmplcs 

imaged in Figures A-2, A-3 and A-4 wcrc annealed for 0, 

10 niin, and one week, respectively. Initial plinse

is the sum of 5a and 5b, and provides the 

total thickness map. The thickness map is 

equivalent and consistent with AFM 

topographs of these samples. The NEXAFS 

micrographs provide insight into the 

structure of the polymer interface formed. 

A related issue to phase separation in 

thin films of polymer blends is the wetting 

and dewetting in thin polymer films. We have 

thus investigated a polystyrenelbrominated 

polystyrene (PSIPBrS) bilayer model system 

with the Stony Brook STXM and employed 

the method described above to achieve 

quantitative thickness maps of PS and PBrS, 

respectively. The initial structure was a 30 

nm thick layer of PBrS on top of a 40 nm 

thick PS layer prepared by spin casting each 

Figure A-6: Linear absorption coefficient of PS and film and then floating the PBrS layer on top 

PBrS near the carbon absorption edge. 

of the PS layer. After annealing, which 

initiates dewetting, the sample was 

transferred to aTEM grid for STXM analysis. 

Images were acquired of the same sample area 

separation during the spincasting into small domains is at four energies. Each image contains combined 

observed. After 10 minutes of annealing, - intricate information about the PS and PBrS composition and 

filamentary structures and inclusions are observed, with thickness, with the weight governed by the linear 

the system evolving towards the formation of large and absorption 'coefficient of the two polymers (Figure A-6. 

thick PS domains with a PMMA interconnection layer See inset for chemical structure of PS and PBrS). Figure 

after one week of annealing. The phase separation process A-7 shows the resulting component thickness maps and 

is primarily driven by minimization of the interfacial free underlying thickness profiles. Polystyrene has formed 

energies. In order to differentiate the effects of the relative thick walls along a network of spines of PBrS that form 

absorption of the individual polymers, we employ a as PBrS dewets. There is only a pure PS interconnecting 

singular value decomposition method to extract thickness thin film between the spines. The total thickness map is 

maps of individual components. Figure A-5 shows the consistent with AFM topographs. We attempt to measure 

results of using this technique for the sample annealed the contact angle in these systems as an indirect 

for one week. Figure 5a is the projected thickness map of measurement of the interfacial energies. The NEXAFS 

PMMA, Figure A-5b is the map for PS, and Figure A-5c data clearly shows thought that a contact angle of the 

Figure A-7: 

Quantitative 

equivalent 

thickness map 

of dewetting 

PBrS/PS bilayer. 

(a) PS map, 

(b) PBrS map, 

and 

(c) total thick- 

ness map.

filamentary structures as measured with the AFM is only 

indirectly related to the PBrS profiles and the AFM 

measures primarily the PS walls. The STXM data suggests 

furthermore that the PBrS is actually completely 

encapsulated by PS after annealing. This would be 

consistent with SIMS and Photoelectron Emission 

Microscopy (PEEM) data that indicate that there is no 

or little PBrS at the very surface of the sample. 

In both cases presented, NEXAFS microscopy 

provides new quantitative insight into the composition 

and morphology of the samples investigated, and we 

believe to be at the very beginning of NEXAFS 

microscopy making contributions to the science of 

polymer thin films. A variety of other applications are 

pursued by some of us and other researchers at bcamline 

XIA. These include the characterization of dispersed 

phases in complex polyurethane polymers and the initial 

measurements of the partial miscibility of polycarbonate 

(PC) and poly(buty1ene terephthalate) (PBT) in PClPBT 

blends. NEXAFS microscopy is also making contributions 

to polymer materials that were prepared via the non- 

equilibrium processing technique of mechanical alloying. 

The morphology of blends produced in this way from 

polymers such as poly(ethylenc tcrcphthalatc) (PET), 

Vectra (75125 mol% oxybenzoatc/2,6oxy~iapIitI~oatc), 

ethylene-propylcnc rubber (EPR) and PMMA can he 

readily visualized due to the chcn~ical sensitivity of 

NEXAFS microscopy. NEXAFS microscopy of polymers 

has matured as a tcchniquc and is now systcniatically 

applied to a wide variety of materials. . 

[l] E. G. Rightor etnl., J. Phys. Chcm. A 101, 1950- 

1961 (1997). 

[2] H. Ade et nl., Science 258, 972 (1 332). 

[3] X. Zhang etnl., Nucl. Instrum. Mcth. in Phys. Rcs. 

A347,43 1-435 (1 994). 

[4] Data acquired with the XI A STXM dcvclopcd by 

the group of Janos Kirz and Chris Jacobscn at 

SUNYPStony Brook, with support from DOE and NSf. 

Zone plates made by S. Spector and C. Jacohsen (Stony 

Brook) and D. Tennant (Luccnt Technologies/Bcll Labs) 

with support from NSF. HA, DAW and APS arc 

supported by NSF Young Investigator Award (DMR- 

9458060). SQ, SG, MR and JS are supported by NSF.

Microbeam Diffraction Studies of Interfacial Strain 

I.C. Noyan, J.L. Jordan-Sweet, E.G. Liniger, and S.K. Kaldor (IBM Research 

Division, Yorktown Heights, NY) 

Modern integrated circuits may have millions of 

transistors and a comparable number of passive circuit 

elements connected by submicron wide metal lines. The 

total length of these fine wires may exceed hundreds of 

meters. In general, this wiring is distributed over several 

levels, separated by dielectric material to prevent shorts. 

Millions of metal-filled holes (vias) provide the 

interconnections between these levels. To achieve (typical) 

failure rates below one chip per thousand, the on-chip 

structures must be built to very exacting specifications; a 

few atoms of a contaminant in the wrong place may cause 

failure. In addition, significant material problems must 

be solved, often at a basic level. 

The thermal expansion coefficient mismatch 

between different materials may cause stresses that can 

Figure A-8: Contour plot of the variation of Si (004) reflection 

intensity with position on a 2x2 mm area section of the sample. 

The circular area in the middle corresponds to the intensity 

increase observed as the microbeam traversed over one Al 

dot. The edge of the neighboring dot is seen in the lower 

right-hand corner. The data was acquired by step-scanning 

(with 50 micron steps along both axes, 1600 points) and 

counting for 60,000 monitor counts (about 5 seconds) at each 

position. The data were then normalized to yield diffracted 

counts per monitor count (cpmon) and processed to form equi- 

intenisty contours. 

result in fractures in the wiring or in the passivation levels 

that insulate them. In addition, the tremendous current 

densities seen by the fine metal wires (in excess of lo6 

amps/cm2) may result in electromigration, where the 

electron flux knocks atoms from the wiring lattice and 

sweeps them along, causing voids at the cathode end. The 

displaced atoms aggregate close to the anode end of the 

wire (which is terminated by a via with different 

metallurgy) and cause very large compressive stresses that 

can actually rupture the passivation. The basic design 

principles that are used to overcome these problems are 

based on continuum mechanics with corraboratiq data 

from large specimens. These formulations may not be 

appropriate for the small domains encountered in 

microelectronic devices; in some cases the material is too 

close to an edge such that edge effects 

dominate and, in other cases, there simply -. 

are not enough atoms around to yield a 

continuum. Microdiffraction is used to 

obtain the basic boundary conditions to 

develop the deformation mechanics of small 

domains and, in addition, to yield structure 

and phase information. 

The first monochromatic x-ray 

microbeam diffraction experiments at 

Beamline X20A have been made by IBM 

scientists in Fall 1997. For this purpose a 

dedicated endstation which had been under 

construction during 1997 at Beamline X20B 

was used. This system is based on a twocircle 

Huber Goniometer and it uses tapered 

capillary optics for focussing the beam, 

micrometer precision sample-stages for 

specimen positioning, and energy-dispersive, 

linear and/or single channel detectors. 

Beam sizes ranging from 2 to 25 microns 

have been used tb characterize the 

orientation and strain distribution on a 

variety of thin-film samples. In this first set 

of experiments, the applicability of 

continuum equations (which are based on 

global averages or large homogeneous 

volumes) to domains containing limited 

volumes of material was investigated. - 

One case in particular is the interfacial 

strain state of patterned thin A1 films on

single-crystal Si wafersl'l. In this experiment an array of 

1 mm-diameter, 850nm-thick Al dots evaporated on a 00 1 

Si substrate was examined. A micro-beam topograph of 

the Si 004 reflection was constructed by mapping the 

integrated intensity as a function ofposition on the wafer. 

An example is shown in Figure A-8. The intensity 

contours corresponding to the region under the Al dot 

are 2x higher than the intensity from the bare Si substrate. 

This intensity enhancement is due to the transition from 

dynamical to kinematic scattering since the thermal 

stresses between A1 and Si distort the Si under the thin 

film featuresl2.'1. A high-resolution scan of the Si 004 

Y (mm) 

Figure A-9: The variation in Si (004) intensity across an Al dot. 

The step size is 2 microns. Note that the "baseline" is actually 

significant intensity from the bare Si wafer. The intensities are 

normalized to the monitor counts (cpmon). Error bars are not 

shown because of the high density of data points, but are 

approximately +/- .006 cpmin. 

reflection across an Al dot (Figurc A-9) sho\vs multiple 

maxima and n~iniriia on a Icmgtli scalc much I;lrgcr than 

the beam size (60-250 niicromctcrs vs. 2x10 

micrometers). In contrast, the strain state expected from 

the continuuni "Shear I,ag" formulationl"l predicts only 

two maxima at each end ofthc film, wdlicli dec;~~~~iiootlily 

down to the base (dynamical) intensity at the "critical 

length" as one moves closer to rlic center. l'he multiple 

extrema observed experimentally indic;~tc that the strain 

transfer is periodically interrupted! This result has 

significant implications in the analysis of adhesion and 

stress transfer at thin film/suhstrate interfaces. It also 

sho\vs that common assumptions 

ahout thin film properties may be 

invalid on a local scale. Microhenm 

x-ray diffraction provides a tool for 

testing these assumptions by providing 

data on a small Icngtli scale with 

minimal snmplc prcpar;ltion. 4 

[I] I.C. Noy:~n, 1.1.. Jordan-Sweet, 

E.G. Liniger, and S.K. Kaldor, A/)/)/. 

P/y. Let. (sulmittcd). 

[2] L.V. Amroff, I'lcmcnts ofX-ray 

Crystalloyraphy, Mr.Gi.crri1-Hill, pp. 

207-227, (1 968). 

[3] R.D. Cullit): F,lemcnts ofX-r;y 

Diffrxtion, 2nd ed., Ah/koil Wr~l(y 

pp. 268-270, (1 978). 

[4] W.T. Chen and C.W. Nelson, 

IRM J. Rcs. n d Dm., 23, 1 79 (1 979); 

H.L. Cox, Rriticl~J. A/)/)/. /'/JJJ.L, 3, 72 

(1952); D. Hull and T.W. Clync, &I 

Introduction to Composite Materials, 

2nd cd., C:criub~.id~e IJi~iurvrity I'IY:FS., 

pp. 105-121, 143-147, (1996).

The Structure of the GroEL/GroES/ADP Complex 

Z. Xu, A. Horwich and P. Sigler (Yale University) 

The structure of the molecular chaperone GroEL 

in complex with a partner assembly GroES in the presence 

of bound ADP, was determined to a resolution of 3.0 a 

using x-ray diffraction data collected at beamline X25 by 

Z. Xu, A. Horwich, and I? Sigler of Yale U. and the 

Howard Hughes Medical Institute (HHMI)[ll. The 

GroELIGroES complex facilitates the folding of other 

proteins, and how this is accomplished is an important 

problem in modern biology. GroEL consists of two backto-back 

7-fold rotationally symmetric rings, that enclose 

two large, non-contiguous central cavities in which an 

unfolded protein can be bound. GroES consists of a single 

7-fold rotationally symmetric ring, with mobile loops 

extending from its rim. In the presence of the nucleotide 

ATI>, GroEL and GroES interact via these loops to form 

diffraction data show that the overall structure of this 

complex undergoes a substantial change upon the binding 

of the nucleotide, arising from movements of the domain 

components of one of the GroEL rings (Figure B- 1). This 

creates an enlarged cavity from which the bound protein 

can be released, upon dissociation of the GroES ring from 

the GroEL. The diffraction data also provide insight to 

the binding of the nucleotide to the complex. The crystals 

of this complex have a very large unit cell and diffract x- 

rays very weakly and anisotropically, and moreover are 

relatively small. Access to the high beam intensity ofX25 

was mandatory in order to determine its structure to such 

high resolution. . 

[I] 2. Xu, A. Horwich, and I? Sigler, Nature 388, 741an 

asymmetrical GroELIGroES complex. The x-ray 750, (1997). 

Figure B-I : Overall architecture and 

dimensions of GroEL and GroEL-GroES- 

(ADP), Van der Waals space-filling 

models ( 6 A spheres around Ca ) of 

GroEL (left) and GroEL-GroES-(ADP), 

(right). Upper panels are outside views, 

showing outer dimensions; lower panels 

show the insides of the assemblies and 

were generated by slicing off the front 

half with a vertical plane that contains 

the cylindrical axis. Various colors are 

used to distinguish the subunits of GroEL 

in the upper ring, with shading 

indicating domains; dark hue, equatorial 

domain; medium hue, apical domain; 

lightest hue, intermediate domain. The 

lower GroEL ring is uniformly yellow. 

GroES is uniformly gray.

Crystal Structure of Bovine Mitochondrial Cytochrome bcl 

Complex, An Essential Component of Cellular Power Plant 

D. Xial, C. A. Yu2, H. Kim1, A. Kachurin2, L. Zhang2, L. Yu2, 

and J. Deisenhoferl 

HHMl 9 Department of Biochemistry, U. Texas, Southwestern 

Medical Center 

Department of Biochemistry, Oklahoma State U. 

Figure B-2: Partial structural model of the dimeric 

cytochrome bcl complex with polypeptides drawn as 

ribbons, hemes as stick models, and the Rieske iron-sulfur 

center as balls. Eight of the eleven subunits (corel, core2, 

cytochrome b, Rieske ISP, subunits 6, 7, 10, and 11) are 

completely traced and their sequences assigned. The top 

of the model is in the mitochondria1 inter-membrane 

space, the middle spans the membrane, and the bottom 

is in the matrix space; approximate dimensions are given 

for each region. 

All living cells use A'1'1' (adcnosinc 

5'-triphosphatc) as a form of energy to 

sustain vital ccllulnr proccsscs esscntiul for 

survival. ATI' is constantly bcinggcnelntcd 

in a ccllular orcSancllc called mitochondria 

- the ccllulnr power plant, and the bcl 

coniplcx is one esscntinl component of 

mitochondria directly involved in ATI' 

synthesis. The bcl cornplcx performs an 

intermediate step in cellul;~r respiration 

which involvcs a series of chemical 

reactions that frees cncrp in the form of 

ATP from food for use in cellular 

metabolism. 

Cytochrome bcl complex 

(ubiquinol-cytocliromc c oxidorcductnsc, 

bcl) is the middle segment of the 

respiratory chain in almost all acrohic 

organisms, and an essential component in 

the photosynthetic machincry in p~r~lc 

bacteria. Green plants use highly 

homologous bGf complex as part of their 

energy photosynthetic appnratus.'Ih bcl 

complex is an integral rncmhrunc protein; 

it couples the electron transfer from 

ubiquinol to cytochromc c to the proton 

translocation across the membrane to 

generate a difference in pH and 

electrostatic potential to drive ATI' 

synthesis. By determining the hcl coniplcx 

structure, we will be one step closer to a 

complete understanding ofccllular of A'I'I' 

generation. 

Mirochondrial bcl complex from 

bovine heart consists of 11 different 

subunits, nvo b- type herncs, one c-type 

heme and an iron-sr~lh~r cluster with a total 

molecular weight of 250 Kd. The hcl 

cornplcx from bovine heart was prificd

and crystallized, and bcl complex crystals can be cry0 

frozen for stable data collection; they possess the symmetry 

of space group I4122 with cell dimensions of a=b=l53.7 

A and c=597.5 A. Synchrotron radiation sources was a 

critical factor in the successful structure determination. 

The use of beam time at beamline X12B of NSLS allowed 

data collection of both native and heavy atom derivatives 

in a relatively short period of time, a task that would have 

been impossible with a conventional x-ray source; the 

tunability of the x-ray wavelength at X4A enabled us to 

quickly and convincingly identify positions of iron atoms 

that are associated with redox-active prosthetic groups in 

the bcl complex, and detect movement of the Rieske Iron 

Sulfur Protein (ISP); the high-flux x-ray beam at X25 

permitted collection of a complete native data set to 2.7 

A resolution, making the refinement of bcl structure 

possible. 

The structure of bcl was determined 

using MIRAS method with seven heavy 

metal derivatives. The current atomic model 

of the bcl complex contains eight subunits 

completely sequence assigned, including 

corel, core2, cytochrome b, Rieske ISP, 

subunits 6, 7, 10 and 11; three subunits 

partially sequence assigned, including 

cytochrome cl, subunits 8 and 9; and four 

prosthetic groups which include two b-type 

hemes, one c-type heme and a 2Fe-2s cluster 

with a total number of amino acids residues 

in the model near 2000. 

The bcl complex forms a dimer in the 

crystal, and is 155 A tall and 130 A wide 

(Figure B-2). The whole complex can be 

divided into three regions: The membrane- 

spanning region is about 42 A thick with 

26 trans-membrane helices for the dimer; 

the cytochrome b dimer contributes 16 

helices, cytochrome cl, the Rieske ISP, 

subunits 7,10, and 11 account for the other 

five pairs of helices, respectively; projecting 

38 A into the inter-membrane space are the 

water soluble parts of the Rieske ISP and 

cytochrome cl, as well as subunit 8; the 

matrix region of the bcl complex protrudes 

75 A into the mitochondria1 matrix space 

and consists primarily of corel, core2 and 

subunits 6 and 9. 

Taking advantage of the anomalous scattering 

property of iron atoms in the bcl complex, we were able 

to determine the positions of and distances between these 

iron atoms in the bcl complex (Figure B-3), and to 

postulate possible routes for electron transfer within the 

bcl complex. More importantly, by combining 

anomalous diffraction experiments with specific inhibitor 

binding studies, we were able to detect very large 

conformational changes of the Rieske ISP upon binding 

of certain classes of inhibitors. These findings indicate a 

new mechanism for electron transfer from one subunit 

to another within the bcl complex. . 

[l] D. Xia, C.A. Yu, H. Kim, J.-Z. Xia, A.M. Rachurin, 

L. Zhang, L. Yu, and J. Deisenhofer, Science 277,60-66, 

Figure B-3: Anomalous scattering difference-Fourier map 

contoured at 5.1 o viewed parallel to the membrane space 

at the top and the matrix space at the bottom. Peaks were 

assigned to heme b,, b, and cl and to the Rieske iron-sulfur 

cluster, respectively, as shown. Distances between some iron 

pairs are indicated.

Structural Lyme-ology 

C. L. Lawson, H. Li, M. Becker, and W. Ding (BNL Biology Department) 

The crystal structure of an antigenic protein from 

the outer surface of the Lyme disease bacterium has been 

determined by x-ray diffraction methods. OspA (outer 

surface protein A) is an abundant inimunogenic 

lipoprotein of the Lyme disease spirochete Borrelia 

burgdorferi that is being developed as a vaccine to protect 

humans from being infected aftcr a tick bite. Making 

use of data from beam lines XI 2C, XI 2B, and X25, the 

crystal structure of a recombinant form of OspA was 

solved in a complex with thc Fab fragment of a mouse 

monoclonal antibody, and was refined to a resolution of 

1.9 All'. OspA is formed from a large 

antiparallel beta-sheet, with an unusual 

nonglobular region of "freestanding" 

sheet connecting globular N- and C- 

terminal domains (Figure B-4). 

Another unusual fcaturc of the folding 

pattern in the nonglobular region is 

arrays of residues with alternating 

charges. A hydrophobic cavity buried 

in a positively charged cleft in the C- 

terminal domain is a potential binding 

site for an unknown ligand. The 

binding region of this antibody is 

biologically interesting because it 

overlaps with a well conserved surface 

in the N-terminal domain that is not 

accessible on the spirochete. This 

suggests that OspA interacts with other 

membrane proteins. The other end of 

OspA, the C-terminal domain, is what 

is exposed in the spirochete, and this, 

therefore, is the imm~~nologically 

interesting part. Recently, native and 

tungstate-derivative MAD data have 

been collected at X12C and X25 on 

crystals of OspA complexed with the 

Fab fragment of an antibody that 

inactivates the Lymc spirochete. 

Preliminary interpretation of these data 

suggests that the antibody binds to a 

highly variable region of the C-terminal 

domain, which would havc important 

implications for world wide 

effectiveness of OspA-based vaccines. 

Data also havc been collected on the 

highly homologous OspR lipoprotein, both ;11onc and in 

a complex with the Fab fragment from an antihody t l~t 

causes 1,yme spirochetes to self-destruct. Multi-w;~vclcngth 

anomalous diffraction (MAD) data will soon be collcctcd 

on tungstate-derivative OspR crystals. Patterson maps 

calculated from a single wavclcngth dntnsct at the 

tungstnte L-111 edge havc already pin p in ted the hcavy- 

atom binding sites. II 

[I] H. Li, J.J. Dunn, R.J. hft, and C.I.. Lawson, 

A.or. Ndt. Arm! Sri. IJSA 94, 3584-3589, (1 997). 

Figure B-4: Ribbon diagram of the first solved complex 

between OspA and an antibody fragment (Fab), published in 

Li etal., 1997. OspA is represented by cyan arrows (O-strands), 

grey ropes (turns) and a magenta cylinder (tr-helix).

The Structure of the Human Natural Killer Cell Inhibitory 

Receptor 

Q. Fan, L. Mosyak, and D.C. Wiley (Harvard University) 

Natural killer (NK) cells lyse abnormal cells 

deficient in class I major histocompatibility complex 

(MHC) expression. Killer cell inhibitory receptors 

(KIR) on human NK cells prevent the lysis of target cells 

bearing specific class I MHC molecules. The x-ray 

structure of a p58 KIR (p58-c142) was determined at 

I .7 A resolution using the multiwavelength anomalous 

diffraction (MAD) method. MAD data of a single 

selenomethionyl p58-c142 crystal were collected to 2.2A 

with a 300 mm diameter MAR Research image-plate 

system on the X25 beamline of the NSLS. Based on the 

x-ray absorption spectrum of the Se-Met p58-c142 crystal, 

three wavelengths for data collection were chosen, which 

included one wavelength at the absorption peak (0.979 1 

A), one at the inflection point (0.9794 A), and a third at 

a remote high energy point (0.9639 A). A native data set 

was collected to 1.7 A on F-1 beamline at CHESS. MAD 

phasing was treated as a case of multiple isomorphous 

replacement. The initial MAD map was improved by 

Figure B-5: Structure and 

topology of p58-42 KIR. KIR 

domain Dl is N-terminal, 

and D2 is C-terminal; ABED 

P-sheet (dark orange) and 

C'CFCA' P-sheet (light 

orange); WSKSS and VSAPS 

motifs (red); potential 

glycosylation sites at 

asparagines 46, 63, 123, 

and 157 (black). 

density modification. A model of p58-c142 KIR was 

traced from both the density modified and unmodified 

electron density map. The atomic model has been refined 

against the native data set at 1.7 A resolution to a 

crystallographic R-value of 20.6% (Rf,,, = 25.4%). 

The p58-c142 KIR structure has tandem 

immunoglobulin-like domains positioned at an acute, GO 

degree angle (Figure B-5). Loops on the outside of the 

elbow between the domains form a binding site 

projected away from the NK cell surface. The topology 

of the domains and their arrangement relative to each 

other reveals a relationship to the hematopoietic receptor 

family. We propose, by analogy to the hematopoietic 

receptors, that signalling by KIR may involve receptor 

dimerization. . 

[I] Q.R. Fan, L. Mosyak, C.C. Winter, N. Wagtmann, 

E.O. Long, and D.C. Wilery, Nature 389, 96-100, 

COOH

The Structure of the Cre RecornbinaWDNA Complex 

F. Cuo, D.N. Copaul, and G.D. Van Duyne (University of Pennsylvania) 

Genetic reconibination involves the breaking and 

rejoining of DNA strands between two sites to provide a 

new strand connectivity and therefore an alternative 

organization of the genetic code. Organisms LISC DNA 

recombination for a nun~bcr of purposes, including the 

generation of genetic diversity, the repair of damaged 

DNA, the integration and excision ofviral genomes into 

and out of thc host chromosome, the regulation of gene 

expression, and in ensuring the stable inheritance of 

circular chromoson~es and plasmids. The lambda 

integrasc family of enzymes that n~ediates recombination 

in bacteria and yeast recognizes specific DNA sequences 

and carries out the exchange of DNA strands only at these 

sites!". The bacteriophage P1 Cre recombinase, a nieniber 

of the lambda integrasc family, carries out site-specific 

recombination between 34-base pair DNA sequences 

called IoxP sites'". The simplicity of the CreIloxP system 

(no other proteins or DNA sequences are required) has 

led to a rapid rise in its use as a tool in a number of 

strand \ 

exchange dleavage 

Figure B-6: Representation of the cleavage, exchange, 

and recombination processes involved in the breaking and 

rejoining of two DNA double helices, mediated by the 

bacteriophage PI Cre recombinase. Two successive cycles 

of strand cleavage, exchange, and recombination are 

required to fully carry out the recombination event. 

genetic engineering experiments, particularly those 

involving the study ofgene function in transgenic mice!'!. 

The work described here involves the recornhination 

rcaction between Cre recombinase and its DNA substrate, 

the IoxP site. A cartoon representation of this reaction is 

shown in Figure B-6. T~vo Cre molecules bind to each of 

the two loxP substr.~tes and bring the douhlc-stranded 

helices together to form a rccomlination synapsc. Crc 

then clenvcs two of the four DNA strands in the synapse, 

using a tyrosine sidc chain as a nuclcophile. Transient 

phosphotyrosine links between protein and DNA arc 

forn~ed, thereby conserving the energy of the 

phosphodiester bond. The free DNA strand produced 

upon cleavage then acts as a nuclcophilc, attacking the 

phosphotyrosine linkage located across the synapse on 

the partner substrate. This results in the exchange of two 

of the four DNA strands and formation of a Hollidny 

junction intermediate. A complementary set of clcavngc 

and strand exchange steps on the remaining pair of DNA 

strands then complctcs the 

recon~bination event and gives 

recombinant DNA duplexes. 

In work carried out at the X25 

and X4A beamlines at the NSLS, G. 

Guo, M. Gopaul, and G. Van Duync 

from the University of I'cnnsylvnnia 

School of Medicine have trapped and 

dcterniined the tl~rec-dimensional 

structure of a Crc-10x1' reaction 

intcrmcdinte where the recomhinasc 

has cleaved the loxP suhstratc to form 

a phosphotpsinc linkage, but is 

unable to complete the strand 

exchange step[". To accomplish this, 

they formed and crystallized a 200 

kD synaptic Crc-DNA complex 

using a suicide loxP substrate that 

loses its attacking nucleotide upon 

cleavage. Crystals of this Crc-DNA 

complex diffrnctcd X-rays poorly on 

home sources and requircd the 

wiggler source and optics at X25 in 

order to obtain the rclativcly high 

resolution (2.4 A) for a structure of 

this complexity. 111 addition, the 

resources of the X4A beaniline were 

used to conduct a rnultiwavclcngtli

anomalous diffraction (MAD) experiment using 

selenomethionine-containing Cre recombinase at the Se 

absorption edge. The anomalous scattering contribution 

from 22 selenium atoms in the crystallographic 

asymmetric unit was crucial in obtaining crystallographic 

phases to interpret the structure. 

The Cre-DNA intermediate structure is shown in 

Figure B-7. Four recombinase molecules (green and 

purple ribbons) form a pseudo-fourfold symmetric 

tetramer that is held together by a network of protein- 

protein interactions. The cleaved loxP sites (gold ribbons) 

have been bent by about 90' and adopt a nearly square 

planar configuration. The green recombinase molecules 

reaction and has both supported a number of recent 

proposals about how the reaction occurs 

. 

and has provided 

a fresh view of other aspects. The structural model also 

promises to serve as an important starting point for the 

design of improved recombinases and substrates for use 

in genetic engineering applications. 

[I] N.L. Craig, "The Mechanism of Conservative Site- 

Specific Recombination", Annual Review of Genetics 22, 

77-105, (1988). 

[2] N. Sternberg, D. Hamilton, S. Austin, M. 

Yarmolinsky, & R. Hoess, "Site-Specific Recombination 

have cleaved the loxP site and formed pho~phot~rosine and its Role in the Life Cycle of Bacteriophage PI", Cold 

bonds to the DNA. The purple recombinase molecules Spring Harbor Symposia on Quantitative Biology 1, 297have 

not cleaved the DNA substrates and one of the 

interesting questions addressed by this structure involves 

309, (1981). 

understanding how the recombinase tetramer coordinates [3] B. Sauer, "Manipulation ofTransgenes by Site-Specific 

the cleavage reactions. The free ends of the cleaved DNA Recombination: use of Cre Recombinase", Methods in 

strands have been pushed towards the center of the 

synaptic complex, in what appears to be the start of the 

Enzymology 225, 890-900, (1993). 

strand transfer process. The Cre-DNA synaptic [4] F. Guo, D. N. Gopaul, G. D. Van Duyne, "Structure 

intermediate structure has provided the first three- of Cre Recombinase Complexed with DNA in a Sitedimensional 

framework for understanding many aspects Specific Recombination Synapsen, Nature 389, 40-46, 

of the lambda integrase family site-specific recombination (1997). 

Figure B-7: Ribbon 

representation, based on x- 

ray diffraction results, of the 

Cre-DNA intermediate 

formed following DNA 

cleavage, but for which the 

strand exchange process 

was not completed. DNA 

strands are shown as gold 

ribbons, and the Cre 

recombinase molecules are 

shown as green and purple 

ribbons. The cleaved DNA 

loxP sites have been bent 

to form a nearly square 

planar configuration, and 

the free ends of the cleaved 

strands point toward the 

center of the complex, to 

strand exchange.

Crystal Structure of the P4-P6 Domain from a Group 

Ribozyme Reveals Principles of RNA Packing 

J. Cate and J. Doudna (Yale University) 

The discovery that RNA can function as a biological several strong peaks whose positions could I,c refined and 

catalyst, or ribozymc, has raid important qucstions cross-checked. Tlic osmium derivative was uscd to solvc 

about the chemistry and evolution of enzymes. Seveml the P4-P6 crystal structure by multi~~~nvelength ;lnom;llor~s 

classes of ribozymes have been identified and diffraction (MAD) with dnt;l measured nt NSI,S hcamlinc 

charactcrizcd, but until rcccntly thcrc was little 

information about the structurc of RNA. Thc scquenccs 

of most families of rihozymcs consist of a conscrvcd series 

of short base-paircd stems (helices) connected by "loop" 

regions. Biochemical expcrinients suggested that thc 

helices of large RNA molcculcs often pack into globular 

structures with solvent-inacccssihle cores, much like 

proteins. 

Group I self-splicing introns, the first class of 

ribozynics discovcrcd, havc thc rcniarkable ability to cxcisc 

themselves from precursor transcripts without the aid of 

any protein. The structure of the RNA holds the key to 

understanding thc self-splicing nicchanism as well as 

evolutionary relationships among ribozymcs. The group 

I intron froni Tetrahymena thermophila has been well 

characterized biochemically, rcvcaling the ribozynic to bc 

comprised of two structural domains. Thc domains can 

be synthesized separately and asscniblcd in trans to 

produce active ribozymes. The 160-nucleotide P4-P6 

domain, containing half of the rcsidues of tlic catalytic 

core, is an independently folding structural unit. 

Following the development of techniques for RNA 

crystallization, crystals ofthc P4-P6 domain were obtained 

that diffracted X-rays to better than 2.8 A resolution. 

The solution of thc P4-P6 crystal structurc was 

achicvcd through an insightful observation by Jamie Cate, 

thcn a graduatc studcnt working on tlic project at Yale. 

Jamie noticed that P4-P6 crystals grew best in the presence 

of tiny amounts of cobalt hcxamminc, a small molccule 

that mimics the geometry of a fi~lly hydrated magnesium 

ion. Since dramatic effects on crystal growth were seen 

with stoichionictric amounts of hcxamrninc to RNA, 

Jamie reasoned that there might bc just a few specific 

X4A (Figure B-8). 

hexammine binding sites present in the RNA. To take Figure B-8: 2.8 A crystal structure of the 160advantage 

of such potential sitcs for making hcavy atom 

dcrivativcs, Janiic obtaincd froni Prof. Hcnry Taubc at 

Stanford a sample of osmium hcxaniniine, and he soaked 

this compound into the P4-P6 crystals. An anomalous 

differcncc Patterson map calculated using diffraction 

intensities measured on a laboratory x-ray source showed 

nucleotide P4-P6 of the Tetrahymena self-splicing 

ribizome. Helices of the conserved catalytic core, in 

blue and red, pack against helices of an extended 

region. Tertiary contacts occur between an A-rich 

corkscrew motif (orange) and the P4 helix (blue), and 

between a tetraloop (gold) and its receptor (green).

The 2.8 A crystal structure of the P4-P6 domain is 

the first crystal structure of an RNA molecule large enough 

to show side-by-side packing of helices. Such packing is 

thought to be necessary to form stable active sites as found 

in self-splicing introns, Ribonuclease P, the ribosome and 

the spliceosome. In the domain, a sharp bend allows 

stacked helices of the conserved core to pack against helices 

of an adjacent region. Two specific long-range interactions 

clamp the two halves of the domain together: a 

magnesium-coordinated adenosine-rich corkscrew plugs 

into the minor groove of a helix, and a GAAA hairpin 

loop binds to a conserved 11-nucleotide internal loop. 

Metal- and ribose-mediated backbone contacts further 

stabilize the close helical packing, giving rise to a solvent- 

inaccessible interior. 

One interesting feature of the P4-P6 structure is 

the discovery of an unexpected new motif that mediates 

both intra- and intermolecular interactions. At three 

separate locations in the P4-P6 molecule, adjacent 

adenosines in the sequence lie side-by-side, stacking 

simultaneously on both sides of the helix. This creates 

an adenosine platform, opening the minor groove for 

stacking or base-pairing with nucleotides from a distal 

RNA strand. This motif explains in part the 

preponderance of adenosines in internal loops of many 

RNAs. 

Most of the contacts that stabilize internal P4-P6 

domain structure as well as the packing of arrays of 

molecules in the crystal lattice involve the minor groove. 

The wide and shallow minor grooves of A-form helices 

are generally more accessible than the deep major grooves. 

However, non-canonical base pairings, loops and bulges 

in RNA can perturb the geometry of a helix, affecting 

the shape and electrostatic potential in localized regions. 

Indeed, local perturbations at tandem G-U "wobble" base 

pairs in the P4-P6 RNA give rise to specific metal binding 

pockets in the major groove: the hexammine binding sites 

used in the structure determination. In two cases these 

sites are occupied by fully-hydrated magnesium ions in 

the native structure. The binding sites expand the known 

repertoire of ligand binding motifs in RNA and may 

provide a general means of derivatizing appropriately 

designed RNAs for x-ray crystallographic analysis. 

Phylogenetic sequence comparisons show that one class 

of these motifs occurs frequently in ribosomal RNAs, 

suggesting a possible mechanism for metal binding in 

the ribosome. . 

[I] J.H. Cate, A.R. Gooding, E. Podell, K. Zhou, B.L. 

Golden, C.E. Kundrot, T.R. Cech, and J.A. Doudna, 

"Crystal Structure of a Group I Ribozyme Domain: 

Principles of RNA Packing", Science 273, 1678-85, 

(1996). 

[2] J.H. Cate, A.R. Gooding, E. Podell, K. Zhou, B.L. 

Golden, A. Szewczak, C.E. Kundrot, T.R. Cech, and J.A. 

Doudna, "RNA Tertiary Structure Mediation by 

Adenosine Platforms", Science 273, 1696-9, (1996). 

[3] J.H. Cate, and J.A. Doudna, "Metal Binding Sites in 

the Major Groove of a large Ribozyme Domain", Structure 

4, 1221-9, (1996).

The Structure of a Component of the AIDS Virus: 

the Carboxyl-Terminal Dimerization Domain of the H IV-1 

Capsid Protein 

T. R. Gamble, S. Yoo, F.F. Vajdos, U.K. von Schwedler, D.K. Worth lake, H. 

Wang, .P. McCutcheon, W.I. Sundquist, C.P. Hill (University of Uta ) 

As reported recentlyl'l we have solved the x-ray 

crystal structure of the C-terminal dimcrization domain 

ofthe capsid protein from the human immunodeficiency 

virus type 1 (HIV-I). The 26-kD capsid protein (CA) of 

HIV-1 results from the action of the well-known HIV 

protease: as the virus buds, a 55-kD polyprotein called 

Gag is processed by the viral protease to produce three 

discrete new proteins - one, called matrix, that binds to 

the viral membrane, the capsid protein which forms the 

conical viral core structure, and a third called nuclcocapsid 

that helps to organize the viral RNA - as well as several 

smaller peptides. These are the major structural proteins 

of HIV, with -2,000 copies of each protein present in a 

single viral particle. 

CA performs several essential roles during the HIV 

life-cycle. Most importantly, CA forms the conical core 

structure that surrounds the viral genome at the center of 

the mature virus. Genetic analyses indicate that Capsid 

also functions during assembly of new virus particlcs and 

6 

as the virus enters a new host cell. Our study focused on 

the COOH-terminal domain of Capsid, residues 146- 

231 (CAI46-231). This donlain contains a strctcli of20 

amino acids, termed the MHR (major homology region), 

that is found in all known onco- and Icntiviruscs, and in 

the yeast retrotransposon Ty-3. As one might expect, 

this highly conserved sequence is essential for viral 

replication, although its precise functions remain unclear. 

Another feature of special interest is the role of CA146- 

231 in mediating Capsid dimcrization; this domain 

dimersizes with the same affinity as the fdl length protein. 

Capsid dimcrization is essential for core formation and 

infectivity, and the assenihly of infectious viral particles. 

In an effort to understand thc structural basis for 

Capsid dimerization and MHR conscrvntion, we 

determined the crystal structures of recombinant 

sclenonicthionine-substituted CA15 1-23 1 at 1.8 A. 

resolution and native (no Se) CA146-231 at 3.1 A 

resolution. Diffraction data for the CAI 5 1-23 1 

Figure B-9: Ribbon diagram of the structure of the HIV-1 capsid domain 

CA(146-231) viewed as a dimer. Two residues required for stabilization of 

the dimer in vivo are shown as stick models near the center of the figure.

crystal-structure analysis were taken at NSLS beamline 

X12C. The structure was solved by the multiwavelength 

anomalous diffraction method (MAD), based on 

scattering from Se atoms that had been introduced to the 

protein in methionine residues. The structure 

determination was relatively rapid, with an electron- 

density map produced and an essentially complete model 

built only 54 hours after data-collection began. Residues 

15 1-2 19 of CAI 5 1-23 1 formed a well ordered globular 

domain in this structure. The standard crystallographic 

R-value is 22.9% and the free R-value (used for cross 

validation of the result) is 27.4% at the end of the 

refinement of the structure of CAI 5 1-23 1. Once the 

CA151-231 structure was known, it was used to 

determine the CA146-231 structure by the method of 

molecular replacement. 

The CA146-23 1 and CA15 1-23 1 structures are very 

similar, with each molecule composed of an extended 

strand followed by four a-helices. Figure B-9 shows the 

structure of the biologically relevant CAI 46-23 1 dimer 

that is formed in the crystals. In this figure, the MHR is 

composed of the helix shown at the lower left (or upper 

right) and the strand that lies behind it in the figure. 

The role of the most highly conserved MHR residues is 

to form a hydrogen-bonding network that stabilizes this 

structure and links it to the helix that is seen end-on near 

the center of the dimer. The structure therefore explains 

the observation that certain "conservative" mutations in 

the MHR, for example Gln to Asn or Glu to Asp, block 

HIV-1 replication; even mutational changes as small as 

the deletion of a single carbon atom appear to disrupt 

the hydrogen-bonding network within the MHR. 

A series of four conserved hydrophobic residues also are 

essential for MHR function; they lie on one surface of 

this helix and contribute to the hydrophobic core of the 

protein. Thus, all of the conserved MHR residues perform 

critical structural roles. Although most of the Gag 

polyprotein is quite variable among other viruses, the 

remarkable conservation of this 20-residue segment 

suggests that the MHR structure mediates an essential 

interaction with a highly conserved binding partner, such 

as a cellular factor or an invariant segment of a viral 

protein. 

CA146-231 possesses almost identical dimerization 

affinity as the full length CA protein. The dimer interface 

is created by the parallel packing of two helices, to create 

a hydrophobic core. It is notable that the dimer interface 

and MHR are distinct non-overlapping structures. Site- 

directed mutagenesis was used to confirm that the dimer 

seen in the CA146-231 crystal is also the dimer interface 

of full-length capsid protein in solution. Two interface 

residues, Trp184 and Met1 85 (see Figure B-9), were 

mutated to Ala in the intact CA. In neither case would 

the mutant protein form dimers in solution, thereby 

indicating that the crystallographic structure is indeed 

the authentic dimer. One of these mutations allowed 

the formation of viral particles in cell cultures, although 

the particles produced were not infectious. This indicates 

that the crystallographic dimer is an essential interaction 

in the assembly and maturation of viral particles, and 

provides another possible target for the design of drugs 

to treat AIDS. 

[I] T.R. Gamble etaL, Science278, 849 - 853 (1997).

Analysis of Model Automotive Exhaust Catalysts: 

The Oxidation and Reduction of CeO, 

D. R. Mullins, D. R. Huntley and S. H. Overbury (Oak Ridge National Labora- 

tory), G. N. Glavee (Lawrence University) 

Modcrn automotive exhaust catalysts aid in the 

removal of toxic emissions by converting the harmful gases 

into more bcnip substances. In particular CO is oxidid 

into C02 and NO, is reduced to N, and O,.''' Current 

automotive f ~~el systems arc dcsigncd to maintain thc air 

to fuel ratio in the propcr stoichiomctric proportions so 

that CO and NO, arc almost fully oxidized and reduced, 

rcspectivcly. However, during accclcration and 

deceleration the air to fuel ratio can movc away from the 

optimal mixturc so that the toxic emissions arc not fully 

convcrtcd. Various matcrials haw bccn added to the 

catalyst formulation in ordcr to widen the air to fuel ratio 

Sputtered CeO, 

I Oxidized Ce Foil r 

window in which the catalyst cfficicntly opcrntcs. One 

important component is CcO,. 1'1 Cerium has tlic ability 

to rcadily convcrt between thc +3 and t4 oxid;~tion states, 

thcrcty. releasing and storing oxygen. In doing so, it is 

able to assist in tlic rcductioti of NO, undcr oxidizing 

conditions. 

In order to understand tlic hch;lvior of CcO,, the 

Surface Science and Catalysis Group at Oak liidgc 

National Lab h a bccn studying the oxid;ltiot~ and 

reduction of Cc metal foil and single crystal CcO, films 

under UHV conditions and small Cc,%r, ,O, particles 

at atmospheric pressure. 

Temperature (K) 

Figure C-1 : The percentage of Ce+3 

in two different CeO, samples as a function of 

annealing temperature. Light Bars - Ce metal foil that was oxidized by exposing it 

to > 1000 L 0, at 300 K. Dark Bars - CeO,(llO) film that was reduced by sputtering 

with Art ions at 300 K.

Ce Metal Foil and Single Crystal 

CeO, Films 

Ce metal oxidizes readily and must be stored in an 

inert gas environment in order to prevent total oxidation 

to CeO,. A oxygen free surface can be prepared in UHV 

and then the degree of oxidation can be varied by 

controlling the oxygen exposure. Various techniques can 

be used to monitor the Ce oxidation state. These methods 

include Ce 4d and valence band 

photoemission (XPS) and x-ray 

absorption spectroscopy (XAS) at 

the 0 1s absorption edge.r31 These 

experiments have been performed 

on beamline X1 B. 

At room temperature low 

exposures of 0, (< 10 L) produce 

Ce(II1) oxide. This layer is fairly 

stable and inhibits the uptake of 

additional oxygen. Large exposures 

of 0, (- 1000 L) are needed to 

produce Ce(1V) oxide. Figure C-1 

(light bars) shows the relative 

amount of Ce+3 and Ce+4 as a 

function of temperature. The Ce foil 

is the most oxidized at 300 K. The 

Ce(1V) oxide layer is themally 

unstable due to oxygen diffusion 

and oxidation of the underlying Ceo. 

The results indicate that oxygen 

transport through the Ce substrate 

is the limiting factor in the oxidation 

of the Ce bulk. The process is shown 

schematically in Figure C-2a. 

The reducibility of fully 

oxidized CeO, was studied by 

examining single crystal CeO, films. 

These films were very difficult to 

reduce showing little evidence of 

Ce+3 even after exposure to > 1000 

L of H, or CO at temperatures up 

to 800 K. These films could only 

be reduced in UHV by sputtering 

with inert gas ions. As shown by the 

dark bars in Figure C-1, the 

sputtered surfaces re-oxidized as the sample was annealed 

above room temperature. These surfaces were also 

thermally unstable due to oxygen diffusion from the bulk. 

This process is shown schematically in Figure C-2b. 

- 

Anneal 

2a) Oxidized Ce Foil 

- 

4 Anneal 

Ox 

2b) Sputtered CeO, Single Crystal Film 

Figure C-2: Models for oxygen migration in two different CeO, 

samples upon annealing. A) Ce metal foil oxidized with > 1000 L 0, 

at 300 K. B) CeO, single crystal film sputtered by Ar+ ions at 300 K.

CexZr,,O, and Rh/ Ce,Zr,,O, Acknowledgment 

The oxidation and reduction ofsniall ccria particles 

at atmospheric pressures were studied by x-ray absorption 

spectroscopy (XAS) at the Ce L,,, edge on beamline 

X19A.I41 Particles with surface areas - 100 m2/g were 

synthesized using sol-gel techniques and hypercritical 

drying. In addition to pure CeO,, mixed oxides were 

prepared with Zr forming Ce,Zr,-,o, particles. Some of 

these oxide were impregnated with 0.5 - 2% Rh, by 

weight. The oxides were reduced in 4% H,/He and were 

oxidized in zero gas air. 

The degree of reduction can be determined from 

several features in the Ce L,,, XAS.[5] As shown in Figure 

C-3a, Peak C is associated with Ce+%nd it decreases as 

the sample is heated in the H2/Hc atmosphere. Peak B,, 

is associated with Cet' and its intensity increases during 

reduction. CeF, and reagent grade CeO, wcrc used as 

standards for Ce" and Ce+" 

spectra, respectively. 

The reduction of CeO,, 

C e Z ,,, 0 and Rh/ 

Ce ,,,, Zr ,,,, 0, is shown in 

Figure C-3b. It can bc seen 

that thc addition of Zr 

enhances the extent of 

reduction at a given 

temperature while the 

addition of Rh reduces the 

temperature at which 

reduction occurs. H 

Research was sponsored by the Division of Chemical 

Sciences, Office of Basic Energy Sciences, U.S. 

Department of Encrgy at Oak Ridge National Laboratory, 

managed by Lockhccd Martin Energy Rcscarch Corp. 

under contract number DE-AC05-96OR22464. 

[l] K. C.Taylor, C/rt/r/. Rm -Sri. Eq. 35,457, (1993). 

[2] J. G. Nunan, H. J. Rohota, M. J. Cohn and S. A. 

Bradley, J. C/rt/rl. 133, 309, (1992). 

[3] D. R. Mullins, S. H. Ovcrbriry and D. R. Huntley, 

SZIIJ%E Sri., submitted. 

[4] S. H. Overbury, D. R. Huntley, D. R. Mullins and 

G. N. Glavee, Cntcr/. Lett., s~ibmitted. 

[5] J. El Fallah, S. Boujana, H. Dcxpcrt, A. 

Kicnneniann, J. Majcrus, 0. Tourct, F. Villain and F. Le 

Normand, J. PIy. Cllrm. 98, 5522, (1994) . 

Photon energy (eV) 


Figure C-3: A) Ce L,,, absorption spectra for (Ce,,Zro,)02 particles in flowing 

4% H, / He as a function of temperature. B) Percent Ce+3 following 

reduction in 4% H, / He as a function of temperature for (Ce,Zr,)O, for 

sample with no Zr or Rh, 50% Zr and no Rh, and 50% Zr and 2% Rh.

Dynamic Effects in Core Excitation of Small Molecules 

B. Kempgens, A. Kivimaki, M.N. Piancastelli, K. Maier, H.M. KO pe, M. Neeb, 

U. Hergenhahn, and A. M. Bradshaw (Fritz-Haber-lnstitut, Ber P in) 

The high resolution capability ofX1B has continued 

to give new insights into dynamic effects in core excitation 

of small molecules. As reported last year, excitation of 

the antisymmetric stretching mode by vibronic coupling 

was observed in the 0 Is photoelectron spectrum in 

CO, ['I. A consequence of this effect is that the core hole 

dynamically localizes on one of the 0 atoms; the same 

phenomenon has been recently observed in the 

photoabsorption spectrum of hydrocarbon molecules 

containing equivalent C atoms[,]. In the photoelectron 

spectrum of the ethane molecule (C,H,) the intrinsic C 

1s bonding-antibonding splitting of ca. 105 meV has been 

established for the first timel31. New measurements of the 

vibrational fine structure of the C 1s and 0 Is main lines 

have been made in CO, as shown in Figure C-4. From 

an analysis of the Franck-Condon factors, the bond 

lengths of 1.079 A and 1.167 can be determined for 

the C 1s and 0 1s core-ionized states. This shortening 

and lengthening of the bond with respect to the ground 

state can be understood from the slightly antibonding 

and slightly bonding nature, respectively, of the C Is and 

0 1s core states in COl4]. In another study, measurements 

of the photoelectron spectra above the C Is threshold in 

the series C2H,, C,H,, and C2H, have called into 

question the existence of shape resonances in the C 1s 

photoionization of these molecules[51. Shape resonances 

can be understood as enhancements of the 

photoionization cross section by angular momentum 

transfer to the photoelectron caused by its scattering on 

the molecular core. This pictures implies that they are 

41.0 41.5 42.0 

4 

42.5 38.5 39.0 39.5 40.0 

Kinetic energy (eV) Kinetic energy (eV) 

Figure C-4: Photoelectron spectra showing the vibrationally resolved CO C 1 s and 0 Is main 

lines. The dashed lines show individual vibrational components before convolution with the 

instrumental function and with an asymmetric lineshape due to post-collision interaction.

due to a single-particle phenomenon and should 

be visible in the single hole photoionization cross 

section. The C2H, photoelectron spectrum in 

Figure C-5a depicts the C2H2 C Is main line and 

its most prominent satellites, S1 and SO, pertaining 

to the triplet and singlet states, respectively, due to 

the valence 1 (K)u-to- l (n)* shake-up 

accompanying the C 1s photoionization. By 

analyzing a series of these spectra taken at photon 

energies over the presumed shape resonance 

position, it is shown that the cross-section of SO is 

enhanced at a few eV above its threshold. The 

same is true for several other satellites, partly due 

to conjugate shake-up processes which involve the 

dipole excitation of the C 1s electron and the 

monopole ionization of a valence electron. Such 

an enhancement results in the peak around 310 

eV in the photoabsorption cross-section in Figure 

C-5b. In contrast to that in the C Is 

photoionization main line, no clear enhancement, 

as would be expected from a shape resonance, is 

observable. A similar phenomenon leads to a 

shoulder in the C Is photoabsorption cross-section 

of C,H,, which was also previously interpreted as 

a shape resonance by other researchers. This study 

raises the question as to whether there exists a 

simple linear correlation between shape resonance 

position and bond length, as has been proposed 

earlier both in gas phase spectroscopy and surface 

science. . 

[I] A. Kivimaki, et al., Phys. Rev. Lett. 79, 998, 

(1997). 

[2] B. Kempgens, et al, Chem. Phys. Lett. 277, 

436, (1997). 

[3] B. Kempgens, et al., Phys. Rev. Lett. 79, 361 7, 

(1 997). 

[4] B. Kempgens, etal,]. Phys. B 30,L74l, (1 997). 

[5] B. Kempgens, et al., Phys. Rev. Lett. 79, 35, 

(1 997). 

C2H2 

hv=353 eV 

satellites 

A 

C I S ' , 

40 45 50 55 60 

Kinetic energy (eV) 

Figure C-5: (a) Photoelectron 

spectrum of C2H2 showing the main 

line and various satellite lines. (b) 

The photoabsorption and single- 

hole cross-sections of C2H2 above 

the C 1 s threshold. 

. 

C 1s-' main linc+satcllites 

300 310 320 330 340 3 

Photon energy (eV)

Monochromatic X-Ray Diffraction and Time-Resolved 

Measurements at High Pressure and Temperature 

J. Chen (SUNY at Stony Brook) 

Crystal structure refinements require accurate 

diffraction intensities. A monochromatic x-ray diffraction 

has many advantages over an energy dispersive diffraction 

for the accurate intensity measurements. Traditionally, 

high pressure in situ x-ray diffraction with a large-volume 

press was carried out in the energy dispersive mode 

(EDXD) because of the apparatus geometry. The pioneer 

attempt to acquire monochromatic x-ray diffraction with 

a large-volume press was made at the Photon Factory['z2J, 

however, the diffraction from sample surrounding 

materials remained as a problem for applying imaging 

plate (IP) detectors to the press. At beamline Xl7Bl, we 

have developed a translating imaging plate system 

interfaced with large-volume press SAM85[31, and 

designed a new high pressure cell coupled with a 

subtraction data processing[*]. These developments first 

time allow us to perform time-resolved structure 

refinements at high pressure and temperat~re[~]. 

A experimental setup is schematically shown in 

Figure G-1. The imaging plates are mounted in a 

specially designed holder held on an optical rail. This 

can be tilted vertically and horizontally to the incident x- 

ray direction. The stage is movable along the incident x- 

ray direction to change the sample-to-IP distance (400 - 

870 mm) and along the axis perpendicular to the incident 

x-ray beam for translating the IP during exposure. The 

holder can be easily taken off from the guide block to 

allow the goniometer arm to move down for EDXD 

measurements. A vacuum ensure two plates, either 200 

mm x 250 mm or 200 x 400 mm size, are kept flat to the 

holder during exposure. When the imaging plate is used 

to record the diffraction pattern, the goniometer arm is 

rotated up to + 35O. In the time-resolved measurements, 

a lead screen with avertical slit in the middle is introduced 

in the front of the imaging plate to define the dimension 

of exposure on the detector. Width of the slit is adjusted 

Figure G-1: Schematic layout of the translating imaging plate system for high P-T x-ray diffraction at the 

X17B1 beamline of the NSLS. The inset on the right shows the high-pressure cell assembly for the large- 

volume apparatus, SAM85. The monochromator is a Laue-Bragg double-crystal focusing monochromator.

Olivine 

direct 

beam 

(111)- 

(031)- 

,211)- 

(222)- 

Spinel 

d~rect 

beam 

(111) 

- (220) 

-(311) 

- (400) 

- (331) 

- (511) 

(440) 

- (533) 

- (731) 

Figure G-2: Time resolved diffraction pattern on the imaging 

plate showing the olivine-spinel phase transition in fayalite 

at 5.9 CPa and 370°C. Left indices indicate the diffraction 

peaks of olivine phase; Right indices indicate those of spinel 

phase. Bottom curve shows the corresponding relation of 

sample temperature and imaging plate position. 

depending on the beam intensity, IP-to-sample distance 

and the transporting speed of the imaging plate. A dircct 

beam stop is mounted on the slit. The bean1 stop blocks 

most of the intcnsity of the dircct beam, and allows the 

direct beam to expose the imaging plate with the same 

intensity as a diffracted beam. 

The olivine-spinel transformation mechanism in 

fayalite was studied by the time-resolved diffraction 

measurements. The experiment was carried out by 

compressing the sample at room temperature into the 

spinel stability field (6.9 GPa) and then heating up the 

sample. The sample transformed from olivine to spinel 

during the heating. A time-resolved pattern was recorded 

when the temperature increased from 300°C to 400°C. 

The transportingspccd ofthe imaging plate was 3.25mm/ 

min. The heating rate was I .75 OCImin. Figure G-2 

shows the diffraction pattern taken with an 8 mm front 

slit and 0.2 nim x 0.2 mm incident x-ray 

beam. he photon energy of tlic x-ray was 

4 1.12 kcV and the sample-to-IP distance 

was 8 12.6 nim. In Figure G-2, the sample 

startcd with olivine phase (on the left) and 

ended up with spincl phase (on the right). 

Indices on the two sides of the pattern 

indicate major diffraction pealts of olivine 

and spincl phases respectively. Most of tlic 

intensity ofthe incident beam was blocltcd 

by a lead stop, with a thickness about 2 

mrn, behind the sample; the rest of the 

intensity made a direct beam niarltcr on 

the top the imaging plate. Some high 

background (e.g. those close to spincl (1 1 1) 

peak) wcrc from boron:cpoxy pressure 

medium. The sample temperature was 

recorded as a function of imaging plate 

position and plotted at the bottom of 

Figure G-2. Thermal relaxation rcsultcd 

in the pressure decrease from 6.9 GI'a at 

room temperature to 5.7 GPa at 420°C. 

It is observed that the spinel phase started 

growing at 365OC and tlic olivine phasc 

con~plctely transformed into spinel at 

390°C at ahout 5.9 GPa. Taking account 

the slit width, there is 52 rnm on the 

imaging plate where tlic two ph;~scs coexist. 

The diffraction pattern of two phnsc 

coexisting region on the 11' was integrated 

as a function of time. After background 

subtraction, multi-phase structure 

refinements were make based on these d:ltc. 

Figure G-3 shows results of tlic sequence 

structure refinements. The empliasis of the 

refinements focused on the atomic occupancy in the spinel 

structure. All the occupancy par:1nietcrs for Fc, Si and 0 

were initially free for fitting. The refinements all rcsultcd 

in the occupancy parameter for 0 close to I. We therefore 

fixed the 0 occupancy to I for filrthcr refincnlcnts. Tlic 

results sho\ved that the occupancy parameters F,, and F,< 

for Si and Fc arc only 73% and 82% when the spincl 

phasc is first recognized as amount of 20%) oftlic mixture 

phases, and with growing of thc spincl phnsc F,, and F,;, 

are increase rapidly. This observation indicates that the 

olivine-spinel transition involves the rearrangement of the 

oxide sub-lattice of hexagonally close-packed olivinc, to 

form the cubic close-packed arrangement of the spinel 

structure, follo\ved by the ordering of metals into tlic 

octahedral and tetrnhcdral voids. 

Mechanism of the olivine-spinel phase tr:~nsition 1i;w 

been investigated by sc\wd groups. Sung and Rurnslf'l

proposed a diffusion-controlled 

process, incoherent nucleation of 

the spinel phase and subsequent 

crystal growth; Kronberg ['I and 

Poirier@] proposed a shear 

mechanism, stacking faults in 

oxygen lattice of olivine 

accompanying cation reordering 

coherently. More interesting result 

reported by Furnish and BassettL91 

from their observation of earlier 

appearance of some diffraction 

lines of spinel phase during the 

phase transition suggested a two- 

step shear mechanism with 

stacking faults prior to the cation 

reordering. However there was no 

sound evidence such as structure 

refinement to confirm any of these 

mechanisms. Our experiments 

first time provide the reliable data 

to support the two-step 

transformation mechanism. . 

Acknowledgments. All 

SAM85 team members have 

contributed to this work, and we 

wish to thank J. Hastings and I? 

Siddons at the NSLS for their 

technical support at the X17Bl 

beamline. The study is supported 

by the State University of New York 

at Stony Brook and the NSFScience 

and Technology Center for High 

Pressure Research (EAR 8920329). 

MPIpub. no. 225. 

121, 1260-1560, zero:4+4 

D 0.3015 A. L-S cycle JIB Obsd. ond Dift. Profiles 

3 , 0 :; , t , > I,,\ 8 > , 

t 

- 20% spinel 

, I,,>!. 3, 3 l,U~,,W*~~ ,,u,,p ,< ,,,m,,q*; y,, - 

psi = 0.79 

-wkb,lhu-* - ~~~'0.82 

P , ,,, 8 9 #,,,,,#,,,,, > ,w,,,,,,,,,!,,,,,:",:",ta,,,,,,,:n,M, .,,,,,,I,, 

I I I I I I 

d.4 d.6 d.a i.0 1.2 1.4 

I 30% spinel 

Fsi = 0.87 

,uww+ ~~~"0.84 

46% spinel 

Fsi = 0.97 

I I :: I I , 3 ,#,/ 1\11, 1, I i ,,.,I1 "!.111111111"11.111,,1,, Il'i"l,il,ll I,,,,, - 

I I I I, I I, I 

-jru----&--- FF =0.91 

Figure G-3: Full Rietveld refinement of selected patterns in the 

time sequence through olivine-spinel transformation in fayalite. 

T. Kikegawa, J. Chen, Y. Kenichi, & 0 . Shimomura. Rev. Sci. Instrum. 66(2), 1335-1337(1995). 

J. Chen, T. Kikegawa, 0. Shimomura and H. Iwasaki,]. Synchrotron Rad 4,21-27(1997). 

See abstract of thk ~ 1 7 bearnline ~ 1 by J. Chen, D. J. ~eidner, M. T. Vaughan, R. Li, J. B. Parise, C. C. Koleda 

and K. J. Baldwin in this report. 

J. Chen, J. B. Parise, R. Li, D. J. Weidner, and M. T. Vaughan, in High-Pressure and Temperature Research: 

Properties of the Earth and Planetary Materials, edited by M. H. Manghnani and T. Yagi, AGU Washington 

D.C., 1998, p129-134. 

See abstract of the X17B1 beamline by J. Chen and D. J. Weidner in this report. 

C. M. Sung and R. G. Burns, Earth Planet. Sci. Lett. 32, 165(1976). 

M. L. Kronberg, Acta Metall. 5, 507(1957). 

J. I? Poirier, in Anelasticity in the Earth, Geodyn. Ser. vol. 4, edited by F. D. Stacey et al. p. 11 3-1 17, AGU, 

Washington D.C. (1981). 

M. D. Furnish and W. A. Bassett, J. Geophys. Res. 88, 10333 (1983).

Synchrotron X-radiation, Ultrasonics, and the 

Composition of the Earth 

M. T. Vaughan (Center for High Pressure Research, 

State University of New York at Stony Brook) 

The primary data about the deep interior of the 

Earth that is relevant to its conlposition are the travel 

times of seismic waves. These data arc used to determine 

the compressional and shear acoustic velocity and the 

density, as functions of depth. To deternline the 

composition of the n~aterials present there (in terms of 

both chemistry and phase), we need to measure in the 

laboratory the equivalent parameters of candidate earth 

materials at equivalent conditions of prcssure and 

temperatures. 

Acoustic velocities of many earth n~aterials havc bccn 

measurcd at elevated pressures and temperatures using 

ultrasonic interferometry for several decades now, however 

only recently have we bccn able to make these 

measurements at prcssure and temperature conditions 

equivalent to the Transition Zone at 400 kni. (-15 

GPa)1',21 . There has long been a problem ofdeternlination 

of the prcssure in these experiments; use of fixed-point 

calibration has been fairly successfirl at room temperature, 

but is much less accurate at high temperatures. 

Synchrotron radiation has been used to address some 

of these issues for over a decade. The change in unit cell 

volume under increasing pressure and temperature is 

measured using x-ray diffraction; the known equations 

of state of various n~aterials such as NaCl and MgO are 

then used to determine the prcssure. With the installation 

of the DIA multi-anvil high prcssure apparatus at the 

superconducting wiggler beam line at the NSLS in late 

1989, we perform thcse experin~ents at precisely 

determined temperatures on fairly large san~ples (-I mni'). 

In the last two years, we have developed a facility to 

measure acousticvelocities using - ultrasonic interferometry 

on samples while they are under high pressure and 

temperature inside the DIA apparatus. The ultrasonic 

sample is surrounded by NaC1, which can be used to 

determine the pressure. In Figure G-4, we show the 

acoustic piezoelectric transducer-tutigstcn carbide anvil 

arrangement and the high-temperature ccll asscnihly for 

the DIA. The WC anvil serves as an acoustic buffer rod 

to transn~it the high-frequency signal (20 to 90 MHz) 

into the cell asscn~bly. 

Using this technique, we havc measured both the 

compressional and shear wave velocities of most of tlic 

major components of the earth's mantle. Thcsc include 

magnesium silicate in the olivincl'l, wadsleyitel~, garnet 

(majorirc)li1, orthopyroxcnclf'l, and perovsl

To Interferometer / 

Platinum Wire 

for Electric CO&&-. 

Spring Loading Devide Acoustic Transducer 

for Acoustic Transducer CulPt Foil for 

Contact Electric Contact 2 mm 

M 

Figure G-4: Diagram of anvil insert and cell assembly for ultrasonic experiments in X17B1. 

[I] G. D. Gwanmesia and R. C. Liebermann, High Pressure Research: Application to Earth and Planetary Sciences 

(ed. by Y. Syono and M. Manghnani), 1992. 

[2] G. D. Gwanmesia, B. Li, and R. C. Liebermann, Experimental Techniques in Mineral and Rock Physics, (ed. 

by R. C. Liebermann and C. H. Sondergeld), PAGEOPH, 141,467 (1993). 

[3] G. Chen, Y. Sinelnikov, and R. C. Liebermann, this issue; B. Li, J. Liu, L. Flesch, R. C. Liebermann, J. Chen, 

and B. Savage, this issue. 

[4] B. Li, J. Liu, L. Flesch, G. D. Gwanmesia, J. Chen, and R. C. Liebermann, NSLS 1996 Activity Report B-142, 

1997 

[5] G. D. Gwanmesia, G. Chen, Y. Sinelnikov, J. Cooke, L. Flesch, M. T. Vaughan, and R. C. Liebermann, NSLS 

1996Activity Report B-141, 1997; G. D. Gwanmesia, G. Chen, J. Cooke, L. Flesch, R. C. Liebermann, and M. 

T. Vaughan, this issue. 

[6] L. Flesch, B.Li, J. Zhang, J. Cooke, R. C. Liebermann, and M. T. Vaughan, this issue. 

[7] Y. Sinelnikov, J. Zhang, and R. C. Liebermann, NSLS 1996 Activity Report B-144, 1997; Y. Sinelnikov, J. 

Zhang, and R. C. Liebermann, this issue. 

[8] G. Chen, Y. Sinelnikov, J. Cooke, D. J. Weidner, and R. C. Liebermann, NSLS 1996 Activity Report B-138, 

1997; G. Chen, Y. Sinelnikov, R. C. Liebermann, and D. J. Weidner, this issue.

Detection of Organic Compounds Associated with 

Carbonate Globules and Rims in the ALH84001 Meteorite 

from Mars 

G. J. FI nn (Dept. of Ph Y sics, SUNY-Plattsburgh), L. P. Keller, M. A. Miller (MVA, 

Inc.), Y~acobsen and . Wirick (Dept. of Physics, SUNY-Stony Brook 

In August 1996, D. S. McKay and co-workersl'l 

reported possible evidence for biological activity on Mars 

in material along fracture surfaces in thc ALH84001 

meteorite, believed to be from Mars. Thcy found 

carbonate globules, which may form by precipitation from 

water, along the fracture surfaces. Dark rims surrounding 

the carbonate globules contain magnetite and iron-sulfide 

grains, similar in size and shape to those produccd by 

terrestrial bacterial''. They also detected organic 

compounds called polycyclic aromatic hydrocarbons 

(PAHs), frquently produced by the decay of living 

material, "found in the highest conccntrations in the 

regions rich in carbonatesn[']. While each of the features 

might have been produced by non-biological processes, 

their close spatial association sug~csts they all formed by 

the same process. They 

concluded that biological 

activity, early in the Mars' 

history, could explain all 

the featured". 

Other investigators 

suggest the carbonates 

formed at high 

temperatures, inconsistent 

with precipitation from 

water[']. In addition, most 

meteorites are 

contaminated by terrestrial 

organic matter, so the 

PAHs found associated 

with the carbonates might 

be from Earth not Mars. A 

recent study determined 

that a majority of the 

organic matter in 

ALH84001 is likely to be 

t e r r e s t r i a l 

contamination[", although 

the same study found 

some pre-terrestrial carbon 

after the carbonates had 

been dissolved. If this 

2-30 

carbon is organic, then 1 0 to 20% of thc organic mattcr 

in ALH84001 was prcscnt prior to its arrival on Earth1''. 

The organic measurements by McKay's group wcrc 

limited by the spatial resolution of thc instrument and 

by their ability to detect only one class of organic 

compounds. Their instrunicnt has a sampling bc:lmspot 

50 microns in sizel'l, thc width of a typical human hair. 

This is comparable to the size ofcntire carbonate globulcs 

(-50 to 100 microns), and much larger than thc dark 

rims (-5 to 10 microns thick) or the individual magnetite 

crystals (tens of nanonietcrs in size). In addition, thcir 

technique was sensitive only to PAHs, not othcr (possibly 

more interesting) organic molecules which are less stahlc 

in the laser desorption process they uscd. 

We employed the Scanning Transmission X-Ray 

- 

5 yrn MARS SAMPLE NO. 1 eVz285.7 

Figure G-5: STXM map of a small section of a carbonate globule from the 

ALH84001 meteorite. The carbon bonding state was measured at the spots 

indicated by the arrows.

Microscope (STXM) on beamline X1A at 

the National Synchrotron Light Source 

(NSLS) at Brookhaven National 

Laboratory to determine the bonding states 

and the spatial distribution of carbon in 

carbonates and rims from the ALH84001 

meteorite[*]. The STXM has a 50 

nanometer analysis beamspot, comparable 

to the size of the individual magnetite and 

iron-sulfide crystals, which allows the 

spatial association of carbon bearing 

compounds to be examined with a 

resolution about 1000 times better than 

that achieved by McKay and co-workers[']. 

We then examined the samples using 

a Spectra-Tech Fourier Transform Infrared 

(FTIR) spectrometer, installed on beamline 

U4IR at the NSLS, to identify the carbon 

bondd51. Beamline U4-IR produces an 

intense infrared light beam, providing a 

sensitivity about 100 times better than the 

conventional laboratory FTIR 

instr~ment[~I. FTIR examination allows 

identification of a wide range of organic 

compounds, not just the PAHs detected by 

McKay et al. ['I, using analysis spots down 

to about 3 microns in size. 

Samples: Fragments of ALH8400 1 

carbonate and rim were embedded in 

elemental sulfur, ultramicrotomed to -200 

nanometers thick, and deposited on an SiO 

substrate. This avoids exposure to the 

carbon-bearing epoxies and substrates 

normally used in preparation for 

Transmission Electron Microscope (TEM) 

and STXM examination. Thus, we insured 

that any carbon we detected was indigenous 

to the samples. 

TEM examination of the carbonate 

samples indicated they consisted mostly of 

large crystals of Mg-Fe-carbonate with some 

regions of fine-gained Mg-Fe-carbonate 

and magnetite. The dark rim samples were 

dominated by feldspathic glass, but 

included large (-5 micron) chromite and 

a few small regions of fine-grained 

magnetite, sulfide, and Mg-Fe-carbonate 

similar to the rim material described by 

McKay et al. ['I. 

STXM Examination: In the STXM 

mapping mode, the energy of the incident 

monochromatic x-ray beam is fixed and the 

sample is scanned beneath the beam. The 

02 

- - 

Spectra 2 : 

0.0 

270 280 290 SO0 Jl(l 

n m ~ . . ~ m a ~ I ~ . . n ~ n . ~ s I ~ a ~ ~ ~ ~ a 9 

t 0a5 Spectra 3 

Figure G-6: Carbon-XANES spectra of two spots (shown in 

Figure G-5) on a carbonate globule from ALH84001. Spot 

1 has a strong absorption at 290 eV, indicating the carbon 

is bound in carbonate, while Spot 2 has three absorptions, 

at 284.9,286.5, and 288.2 eV, suggesting the presence of 

organic carbon at this spot. Spot 3 is a carbon-rich spot 

on the rim sample. It shows strong absorptions at 284.5 

and 288.2 eV, indicating the rim contains a different type 

of carbon than that in the globule.

Wavenumber (cm-1) 

Figure G-7: FTlR spectra of the C-H stretching region of a Rim sample (top) and a Carbonate Globule 

sample (bottom) from the ALH84001 meteorite. The Rim sample shows two strong absorptions, at 2918 

and 2850 cm", consistent with the positions and relative intensities of the C-H, stretching vibrations in an 

aliphatic hydrocarbon. The Carbonate Globule sample shows a single strong absorption at 2964 ern.', 

consistent with a C-H,stretching vibration, and a weaker, broad absorption from 2900 to 2950 cm.'. This 

sample may also show a very weak, broad feature from 2990 to 3060 ern.', possibly associated with 

PAHs. 

absorption of the sample is measured at each pixel. Since 

the absorption of carbon increases sharply at 290 eV, the 

carbon K-edge energy, while the absorptions of other 

elements are approximately constant in a narrow range 

of energy near the carbon K-edge, a pixel showing an 

increase in absorption between the map just below the 

carbon K-edge (e.g., 280 eV) and the map just above the 

carbon K-edge (e.g., 300 eV) contains carbon (see image 

in Figure G-5). 

In Carbon-X-ray Absorption Near Edge Structure 

(C-XANES) mode the beam hits a fixed position on the 

sample, and the monochrometer is scanned over the 

energy range from 270 to 310 eV. Absorptions in this 

region are characteristic of particular carbon bonds. The 

C-0 bond in carbonate gives rise to a strong absorption 

near 290 eV but no absorption near 285 eV, while C-C, 

C=C, and C-H bonds have strong absorptions in the 284 

to 287 eV range. Thus, C-XANES is a sensitive technique 

to detect organic (or graphitic) carbon in a matrix of 

carbonate, making the STXM particularly well suited to 

identitjing non-carbonate carbon in a matrix of carbonate 

(as is the case for the ALH84001 carbonate and rim 

samples). 

The C-XANES spectra of the carbonatc samples 

showed a strong absorption at 290 eV, characteristic of 

the C-0 bond in carbonate. These samples also showcd 

weaker absorptions at 284.8 eV, 286.5 eV, and 288.2 eV 

(see Figure G-6). The relative intensities of the latter 

three absorption peaks were approximately constant 

(where they could be detected), suggesting that 

throughout the carbonate saniples a single additional 

carbon-bearing phase dominated the absorption. 

However these three peaks varied in intensity with 

position on the sample, ranging from spots showing only

the 290 eV carbonate peak to spots showing strong 

absorptions at 284.8 eV, 286.5 eV, and 288.2 eV but no 

detectable 290 eV peak. This indicates the second carbonbearing 

~hase is distributed inhomogeneously on the scale 

of the 50 nm beamspot, within the carbonate. Work is in 

progress to correlate the locations of this phase with TEM 

mineralogy. 

Most spots on the rim samples showed no absorption 

at 290 eV, consistent with a low abundance of carbonate. 

Some spots showed two absorption peaks at 284.5 eV 

and 288.2 eV, indicating the presence of C-C, C=C, C- 

0, or C-H bonds. The differences in absorption energies 

and the absence of the third peak in indicate that the 

dominant carbon-bearing phase in the rim is different 

from that in the carbonate globule. Correlation of the 

STXM carbon map with TEM mineralogy indicates the 

carbon-rich phase is associated with fine-grained 

magnetite and sulfide, and may also occur as veins or 

inclusions in the feldspathic glass. 

FTIR Examination: To determine if the dominant 

carbon-bearing compound is different in the rim samples 

and the carbonate globule samples and to determine if 

these phases are organic, the same samples analyzed by 

STXM were examined by FTIR, a technique routinely 

used for the laboratory identification of organic 

compounds. The FTIRspectra of the rim samples showed 

a broad absorption near 1000 cm-', characteristic of silicate 

glass, and two weaker features at 2918 cm-' and 2850 

cm-I, consistent in position and relative depths with the 

stretching vibrations of C-H, in an aliphatic hydrocarbon 

(see Figure G-7). 

The FTIR spectra of the carbonate globule samples 

showed a narrow absorption at + 1500 cm-', characteristic 

of carbonate, and a weaker absorption at 2964 cm-'. The 

feature at 2964 cm-' is characteristic of the C-H, 

asymmetrical stretching vibration. Although a weaker 

C-H, symmetrical stretching vibration generally occurs 

near 2870 cm-I, this feature is absent in the carbonate 

globule spectrum, and is suppressed in certain compounds 

containing C-H, groups. Two even weaker features at 

2920 cm-' and 2850 cm-', consistent with C-H,, were 

also detected at some spots on the carbonate globule 

samples. One particularly good spectrum of the carbonate 

globule sample appears to show a weak, broad absorption 

over the range 2990 cm-' and 3060 cm-', where the C-H 

stretching vibrations (centered at 3030 cm-') of a mixture 

of PAHs would occur. Follow-up measurements to 

determine if we have located the PAHs are planned. 

Conclusions: The combined STXM and FTIR 

measurements confirm, at a much smaller scale than was 

possible in the work of McKay et al. ['I, the close spatial 

association between organic material and the carbonate 

globules and rims in ALH84001. The carbon detection 

limit of the STXM is of order percent level. IfALH84001 

has a similar bulk carbon content other Mars meteorites 

(0.04 to 0.07%[71), then the STXM results demonstrate 

that compared to the bulk meteorite relatively large 

concentrations of organic carbon are associated with the 

carbonate globules and rims. The FTIR measurements 

indicate the rim material contains an aliphatic 

hydrocarbon whose absorption is dominated by the C- 

H, group, while the carbonate globule is dominated by 

the C-H, group absorption. Thus the rim and the globule 

contain different organic compounds. This results seems 

to rule out the simplest form of organic contamination 

of these samples, simple evaporation of an organic-rich 

fluid, which would be expected to leave the same residue 

in both the carbonate globules and the adjacent rim 

material. However, we cannot exclude contamination by 

selective absorption of different organic species onto the 

different mineral substrates. . 

[l] D.S. McKay et al., Science 273, 924-927 (1996). 

[2] R. Harvey and H.P. McSween, Nature, 382,49ff, 

(1996). 

[3] A.J.T. Jull et al., Science 279, 366-369, (1998). 

[4] G.J. Flynn et al., Meteoritics 32, A42, 1997. 

[5] G.J. Flynn et al., Lunar & Planetary Science 

XYIX, Lunar and Plantetary Institute, (1998), in 

press. 

[6] J. Reffner et al., Synchrotron Radiation News V. 

7, 30-37 (1994). 

[7] A.H. Tremain, Geochem. Cosmochim. Acta 50, 

1071-1091 (1986).

Synchrotron Infrared Microspectroscopy: 

A New Technique for Probing the Chemical Composition 

of Bone and its Implications for Understanding 

Osteoarthritis 

L. M. Miller, D. Hamerman, and M.R. Chance (Albert Einstein Center for Syn- 

chrotron Biosciences), G. L. Carr and G. P. Williams (NSLS), Cathy S. Carlson 

(Bowman Gray School of Medicine) 

Osteoarthritis is the leading cause of disability 

among people over 65 years old and affects approximately 

40 million people in the United States (Center for Disease 

Control, 1990). It is characterized by a breakdown of 

the articular cartilage and thickening of the subchondral 

bone. To date, the cause of osteoarthritis is unknown, 

but, an extensive study of cynomolgus monkeys has 

demonstrated that the subchondral bone thickening 

precedes the development of articular lesions.[ll In 

addition, a recent study on humans determined that the 

subchondral bone from patients with symptomatic 

osteoarthritis was hypomineralized compared with that 

from asymptomatic individuals.121 These data suggest that 

the health and integrity of the articular cartilage is 

dependent upon the mechanical properties of the 

underlying subchondral bone. In turn, the mechanical 

properties of subchondral bone arc also dependent upon 

its chemical structure. 

Over a lifetime, bone is continuously remodeling 

itself and the chemical composition of bone is extremely 

important to this process. Chemically, bone is made up 

of both organic and mineral components. The organic 

component is primarily type I collagen, whereas 

hydroxyapatite, Ca,,,(PO,),(OH),, is the mineral 

component of bone. As bone matures, the size, 

crystallinity, and stoichiometry of the hydroxyapatite 

crystals change. Substitutions into the hydroxyapatite 

crystal lattice are common, where calcium can be replaced 

by cations such as Na', K+, MgZ+, Sr", and Pb". Phosphate 

and hydroxide can be replaced by CO,'-, HPOq2, C1 , 

and F-. These substitutions into the hydroxyapatite lattice 

are very important to bone strength, flexibility, and the 

process of remodeling because they affect crystal size, 

density and solubility. Thus, we hypothesize that the 

bone matrix con~position andlor bonc mineral content 

and crystallinity are modified ill situ in a specific manner 

as a function of subchondlal bone thickness. 

We have addressed this hypothesis by cxnniining the 

chemical composition ofsuhchondral bonc using inJ;.mw/ 

micro-sprrtrosropy. Infrared spectroscopy is an analytical 

technique that is sensitive to the chemical components 

in bone. This technique can be i~sed to determine (1) 

protein structure and concentration, and (2) mineral 

concentration, crystallinity, and content (c.g. phosphate, 

acid phosphate, carbonate). The crystallinity rcsillts are 

correlated to hydroxyapatite crystal size and perfection, 

as determined by x-ray powder diffraction. Ry putting 

infrared light through a microscope, infrared spectra can 

be collected on micron-sized regions of bonc in sitrr and 

compared to visible images of the same region. Th~ls, we 

can exaniine the cheniical composition of suhchondrnl 

bone as a function of subchondral bonc thickness, i.c. 

severity of osteoarthritis. 

Inherently, the long wa\~elengths of infrared light 

limit the spatial resolution achievaldc with this technique. 

We have demonstrated that substantial changes in 

chemical con~position occur within 20 pm of the site of 

new bone growth.13"1 This type of spatial resolution can 

only be achieved with a sy~rlwnti.o~~ infrared source. 

Beamline U4IR at the National Synchrotron 1,ight Source 

provides the world's brightest source of synchrotron 

infrared light - I000 times brighter than a conventional

infrared source - permitting rapid data collection at the 

diffraction limit, i.e. 3-5 pm in the mid-infrared region. 

Recently, we used synchrotron infrared microspectroscopy 

to examined the subchondral plate of a knee joint from a 

radiographically normal cynomolgus monkey (Miller et 

al, 1997a, b). The results can be summarized as follows: 

(1) Bone crystallinity decreases and (2) the carbonate / 

phosphate ratio increases as subchondral bone thickens. 

(3) The phosphate / protein ratio is high where 

crystallinity is high. (4) The acid phosphate concentration 

is relatively constant throughout the subchondral bone. 

Since these results suggest that the chemical composition 

of subchondral bone varies with thickness, we hope that 

future experiments as a function of disease severity will 

continue to provide a chemical understanding of the 

molecular basis for subchondral bone thickening in 

osteoarthritis. H 

Figure 1-1 : Schematic drawing of the proximal end of a monkey tibia. 

[I] C.S. Carlson, R.F. Loeser, C.B. Purser, J.F. Gardin, C.l? Jerome, "Osteoarthritis in cynomolgus macaques 111: 

Effects of age, gender, and subchondral bone thickness on the severity of disease", J. Bone &Mineral Res. 11: 1209- 

1217 (1996). 

[2] B. Li, R.M. Aspden, "Mechanical and material properties of the subchondral bone late from the femoral head 

of patients with osteoarthritis or osteoporosis", Ann. Rheum. Dis. 56: 247-254 (1997). 

[3] L.M. Miller, C.S. Carlson, G.L. Carr, G.l? Williams, M.R. Chance, "Synchrotron infrared microspectroscopy 

as a means of studying the chemical composition on bone: Applications to osteoarthritis", SPIE, 3153: 141-148 

(1997). 

[4] L.M. Miller, C.S. Carlson, G.L. Carr, M.R. Chance, ''A method for examining the chemical basis for bone 

disease: Synchrotron infrared microspectroscopy", Cell. and Mol. Biol , in press (1 997).

Macromolecular Crystallography Area Detectors 

L. Berman (NSLS) 

During the 1997 fiscal year, the area detectors for 

all of the macromolecular crystallography beamlines were 

upgraded, or were in the process of being upgraded. The 

overall intention was to make the collection of 

crystallography data to be a less laborious and more user- 

friendly chore, and to reduce the fraction of users' beam 

time (dead time) in which no data could be collected at 

all. 

Beamline X4A, operated by HHMI, had installed a 

Rigaku R-Axis IV automatic imaging plate detector, 

replacing the manual Fuji imaging plates with off-line 

readout. The new detector contains two plates, allowing 

one plate to be read out (in about 3 minutes) while the 

other is exposing. This allows more efficient use to be 

made of the available beam time and simultaneously 

reduces the necessary labor to run the experiment, because 

manual exchange, readout, and erasure of imaging plates 

(with the concomitant book-keeping) are no longer 

necessary. Beamline X4C, also operated by HHMI and 

undergoing commissioning, will, when operational, use 

an Area Detectors Systems Corp. (ADSC) Quantum-1 

single-module, lKxlK CCD detector, which has a 

readout time of less than 10 seconds. 

Beamline XSC, whose PRT was recently 

reconstituted under the principal auspices of Los Alamos 

National Laboratory, re-commenced a macromolecular 

crystallography program using the X-Ray Research 

(MAR) 300 mm diameter automatic imaging plate system 

that had been used on the X12C (BNL Biology Dept.) 

beamline for several years. This single-plate detector has 

a full-area readout time of about 3 minutes. On beamline 

X9B, under the joint auspices of the Albert Einstein 

College of Medicine and the National Institutes of Health, 

a MAR 345 mm diameter automatic imaging plate system 

was implemented. This new single-plate detector has a 

full-area readout time of under 1.5 minutes. 

Beamline X12B, operated by the BNL Biology 

Dept., had earlier in the year removed the MAR 300 mm 

diameter imaging plate detector, that had been in use 

there, from its base. It was remounted on the long two- 

theta arm in the experimental hutch, that was historically 

employed for small angle x-ray scattering experiments. 

This upgrade allowed for having a very long detector 

distance (so that large unit cell crystals could be studied) 

and, by tilting the two-theta arm, attaining high 

resolution. An ADSC Quantum-4 four-module CCD 

detector (lKx1 K per module), funded by the 1996 DOE 

Basic Energy Scicnccs Facilitics Initiativc Program along 

with some contributions by a few pharmaccutical 

companies, was also ordered for XI 2B, and arrivcd at thc 

start of the 1398 fiscal ycar. 

On X12C, also operated by the BNI, Biology Dept., 

a single-modulc, I Kxl K CCD detcctor, built by a 

collaboration of Brandcis U. and the BNI, Biology Dcpt., 

was installed at the start of the 1997 fiscal ycar. It was 

presented as an optional alternative to the MAR 300 mm 

diameter imaging plate detector which had bccn in use 

on X12C for sevcral years. The bulk of the 

macromolecular crystallography expcrimcnts on X12C 

have been serviced by the CCD dctcctor since. At the 

start of the 1998 fiscal ycar, a four-module CCD dctcctor 

was delivered by the Brandcis / BNI. Biology collaboration 

to X12C for commissioning. It will ultimately be nladc 

available for use on X25. 

On the X25 wiggler bcamlinc, opcratcd by thc 

NSLS, a new MAR 345 mnl diamctcr imaging platc 

system, provided by the NSLS via Facilities Initiativc 

Program funds, was installed to scrvicc macromolecular 

crystallography expcrimcnts. This replaced use of two 

different MAR 300 mm diamctcr imaging platc systems, 

loaned during the past few years to X25 by the BNL 

Biology Dept. and Cold Spring Harbor I,aboratory. Thc 

readout time of the new dctcctor (pcr unit platc area) is 3 

times faster than for the old MAR detectors, and it has a 

finer spatial resolution. In addition, a MAR singlcmodule, 

2b2K CCD dctcctor, with even fincr spatial 

resolution and a readout time of less than 10 seconds, 

was also funded by thc NSLS via the Facilitics Initiativc 

Program, and its delivery is expected in thc 1998 fiscal 

year. It will be able to substitute on X25 for thc MAR 

imaging plate detector, on the same mounting base, when 

desired. The use of this CCD detcctor will not be 

restricted to macromolec~ilar crystallography. Finally, thc 

Brandeis / BNL Biology four-module CCD dctcctor 

mentioned above that was commissioned on XI 2C, will 

become available for use on X25 during early 1998. 

BeamlineX26C, primarily opcratcd in the past with 

focussed and unfocusscd whitc x-ray beam capabilities, 

for Laue macron~olecular crystallography and othcr whitc 

beam experimental programs, by the University of 

Chicago Consortium for Advanccd Radiation Sourccs 

(CARS) and the BNL Applied Science and Biology

Departments, got an NSLS-sponsored upgrade to give it crystallography experimental program, based upon a 

a standard monochromatic beam capability. Cold Spring MAR 300 mm diameter imaging plate system provided 

Harbor Laboratory and the State University of New York by Cold Spring Harbor. This system replaced the manual 

at Stony Brook joined this PRT in the 1997 fiscal year, Fuji imaging plates that had been provided by CARS for 

and began a monochromatic macromolecular several years. W 

Nearly Automatic Macromolecular Crystallography 

at the NSLS 

T. Terwilliger, J. Berendzen (10s Alamos National Laboratory), 

J. Skinner, R. Sweet (BNL Biology Department) 

The pace of protein-structure determination is 

accelerating rapidly, and synchrotron X-ray sources such 

as the NSLS are at the center of this action. Structures of 

protein molecules are in high demand in biotechnology 

because they are important for applications such as drug 

discovery and engineering enzymes for commercial use. 

A structure of a protein molecule can be used to identify 

what each part of the molecule is doing and makes it 

possible to design new protein molecules that have 

improved properties for therapeutic or industrial use. As 

the genome projects continue to produce thousands of 

new protein sequences, the demand for structural 

information on these proteins is increasing. Synchrotron 

beam lines are a key tool for protein structure 

determination. The multiwavelength anomalous 

diffraction (MAD) method takes advantage of the 

intensity and tuneability of x-rays from synchrotron 

radiation sources in obtaining x-ray diffraction data that 

can be used to solve protein structures that contain atoms 

with accessible x-ray absorption edges. 

Until recently, the measurement and analysis of 

MAD x-ray data has been somewhat difficult owing to 

the number of steps involved and to the need for an expert 

to make important decisions about how to handle the 

data. We have assembled a variety of software and 

hardware systems to do much of this work for 

inexperienced users. These include beamline-control and 

data-collection software, gaphical monitoring of data 

reduction, remote monitoring of beamline operations, 

and automatic solving of the phase problem to produce 

an electron-density map of the macromolecule. 

The portions of this that involve acquisition of the 

data, developed by Skinner and Sweet, have been 

produced for the operation of the synchrotron beamline 

X12C at the NSLS. These were highlighted in the 1996 

NSLS Activity Report. Users of the beamline 

communicate with all the experimental apparatus, 

including both the data-collection equipment and the 

beamline components including the monochromator, 

through an easy-to-use gaphical user interface (GUI). 

Important features of the system are (1) its modularity, 

so that different underlying programs or different 

apparatus can be incorporated easily, (2) its ease of use, 

minimizing both user errors and training effort, and (3) 

that most of the experimental operations and parameters 

are logged automatically, again minimizing errors and 

facilitating more-or-less automatic reduction of the data. 

At the time of writing, several different area-sensitive 

detectors are available (see accompanying article by L. 

Berman) for mounting on the four-circle diffractometer 

at the beamline. 

The logging of experimental parameters allows the 

nearly automatic reduction of data. We have constructed 

a graphical diagnostic routine to display color-coded 

information about the course of data reduction, neearly 

all of which is performed while users are present at the 

beamline. A web-based (Java code) tool monitors much 

of the information that is displayed on the GUI at the 

beamline, allowing beamline staff and professors back 

home to keep track of the course of the data collection at 

the beamline. Portions of this software package are in 

use at several beamlines, and we expect to be able to 

disseminate it further. 

To close the loop on the nearly automatic solving of 

structures, a new software package called SOLVE 

developed by Terwilliger and Berendzen can carry out all 

the steps and make all the necessary decisions in the 

analysis of MAD data automatically, and we have installed

it at beamlines X12C, X8C, and X4A at the NSLS. The 

SOLVE software has now bccn run by a numbcr of users 

at these beamlincs and has proven itselfcapable ofsolving 

protein structures in less time than was necessary to collcct 

the x-ray data. 

SOLVE is an expcrt system that automatically 

produces thrce-dimensional elcctron-density maps of 

protein molecules from x-ray diffraction mcasurcnlents. 

For a MAD structurc dctcrmination, a uscr at the NSLS 

used to calculatc electron density for the cntirc structure. 

Thc hard part is coming up with lilicly solutions for thc 

positions of the hcavy atoms and evaluating the relative 

quality ofdifferent solutions. These steps often have bccn 

done manually in thc past, while SOI.Vlt can carry them 

both out automatically. SOIXI', generates a list of lildy 

solutions for the locations of the heaviest atoms in the 

protcin using the program HASSI' to analyze an 

optimizcd Patterson fi~nction derived from thc MAD data 

Figure 1-2: Electron density maps from MAD-phased MkH data around tyrosine 108. All electron 

density maps are contoured at 1.5 o except for D. 

(A) 2.0 A electron density obtained using phases from SOLVE. 

(B) 2.0 A electron density after solvent flattening and histogram matching. 

(C) 1.5 A, 2 fo-fc electron density from current model. 

(D) Difference electron density (fo-fc) contoured at 3.0 o. Positive difference density is contoured 

in grey and negative density is contoured in black. 

will measure diffraction intensities from a single - crystal 

at several x-ray wavclcngtlis spanning an absorption edge 

for an anomalously scattcring atom, such as selenium, 

incorporatcd into the protein. Thcsc arc the raw data 

needed by SOLVE. Thc uscr tclls SOLVE whcrc thcse 

data are locatcd, what thc scattcring propertics of the 

selenium atoms arc at the x-ray wavelengths used, how 

many selenium atoms arc thought to be in thc protcin, 

and how big the protcin is. SOLVE takes this information 

- - 

and constructs an electron density map that can be 

displayed using a graphics program. 

The approach used by SOLVE is similar to the one 

that a protein crystallographer would use. The MAD 

method for structure determination is a kind of 

bootstrapping operation in which thc positions of the 

anomalously scattcring atoms arc first deduced and thcn 

with MADRST. It thcn evaluates each solution for ititcrtial 

consistency and it compares characteristics of tlw clcctron 

density map obtained from that solution with those of 

real electron dcnsity maps of protcins. Using thc bcst 

starting solutions, SOI.VE bootstraps to gcncratc 

improved solutions, and whcn further iniprovcnicnt is 

not possible produces a final clcctron dcnsity map of the 

protcin molecule. 

Scvcral additional fcaturcs make SOIYI much hstcr 

than it otherwise would bc and enable real-tinic structurc 

solving. One, thc MADMRG proccdurc, is a technique 

for extracting the three csscntial picccs of information 

from a set of up to MAD diffraction mcasurctncnts. 

Another, the origin-rcmovcd pattcrson rcfincnicnt 

proccdurc in HEAVY, rcduccs calculation timc by rapidly 

adjusting a solution to match thc x-ray mcasurcnicnts.

Bayesian Correlated MAD Phasing, is a comprehensive 

way to deal with errors in measurement and to deal with 

large differences between crystals used in the diffraction 

analysis. The result of this integration of techniques is a 

fully automated analysis of x-ray diffraction 

measurements. 

The recent successful structure determination by 

Richard Fahrner, Duilio Cascio and David Eisenberg 

(UCLA) at X12C illustrates how useful SOLVE can be. 

The UCLA group was interested in determining the 

structure of a histone protein (HMK) from a thermophilic 

organism. After other methods of solving the structure 

failed, they used established methods for 

selenomethionine incorporation to produced 

selen~methion~l histone protein, and then obtained 

crystals of the protein. Late in 1997, they came to 

beamline X12C at the NSLS to collect data for a threewavelength 

MAD experiment. Since accurate anomalous 

information is required for a good MAD experiment, they 

collected anomalous pairs using the Friedel flip method: 

for every wavelength there were two datasets, sweeping 

the same zones, 180 degrees apart. Their MAD 

experiment consisted of six complete datasets; two at the 

rising inflection point of the absorption spectrum 

(0.9798 A), two at the "white line" peak (0.9799 A), and 

two at a distant point (0.9500 A). Data collection 

proceeded smoothly and rapidly, employing the automatic 

MAD data-collection protocols described above. Two 

factors accelerated high resolution data collection. The 

size and dynamic range of the new four-module Brandeis 

CCD-based detector permitted collection of high 

resolution and low resolution data in a single pass. Also, 

careful oriention of the crystal with respect to the major 

Figure 1-3: 

(left) 

Experimental 

MAD electron 

density from Se- 

MET phasing. 

(right) 

Electron density 

from phases 

after refinement 

of the structure. 

zones allowed collection of a large amount of data in a 

short period of time. The integrated data were about nine- 

fold redundant, greater than 99% complete to 1.4 A, with 

a merging R of 8.1%. Data collection for the complete 

MAD experiment required about seven hours. 

The software package SOLVE was used to perform 

phase determination and assess the quality of their MAD 

experiment. The SOLVE package offered several 

advantages for them. Whereas manual solution of 

Patterson maps in high symmetry space groups with 

multiple heavy atom sites is challenging and time 

consuming, SOLVE offered a simple-to-set-up, automatic 

phase determination alternative. The three-wavelength 

unmerged data with Bijovet pairs were input to SOLVE. 

Using the anomalous and dispersive differences between 

datasets, SOLVE determined a single solution for four of 

five Se-Met sites within 78 minutes running on a 5OOMhz 

DC ALPHA workstation. SOLVE was even able to 

distinguish the correct hand of the structure. The time 

from placing the crystal into the beam until the structure 

was solved was an astonishing 11 hours. 

The initial electron density maps were easily 

interpretable (Figure 1-2). The map quality was then 

improved through solvent-flattening and histogram- 

matching routines using the program "dm" in the CCP4 

program suite. The solvent-flattened map could be 

unambiguously traced for 98 of 154 residues. After 

refinement using XPLOR, the amino acids originally 

traced were returned in the 2Fo-Fc map and more 

importantly, most of the remaining residues could be 

traced. Their current 2.0 A model includes residues 3 to 

154 and 40 water molecules (R=26.3%, Rf,,,=33.7%). .

Soft X-Ray Emission Spectroscopy (XI B) 

K. Smith ef a/. (Boston U.) 

1997 saw the commissioning by Kevin Smith's group partial density of statcs (PDOS). Thus thcsc spectr;~ show 

from Boston Univcrsity of a new high resolution soft x- the behavior of the dominant part of the vnlcnce band 

ray emission spcctromctcr on XI B. There arc only a density of states in AI,Ga,~,N as the AI content is varied. 

handfill of such instruments around the world, and this The band gap for AIkGa,~,N varies from 6.2 cV in AIN (x 

is the only onc dcdicatcd for use at the NSLS. Soft x-ray = I) to 3.4 cV in GaN (x = 0). 'l'hc motion of the top of 

emission (SXE) spcctroscopy allows the bulk clcctronic the valence band is clearly visible in the spectra, shifting 

. * 

structure ofcomplex solids to be measured without regard linearly by 1.5 CV as x varies from 0 to 1. I his indicates 

to the quality or cleanliness of the solid surface. 

In particular, SXE allows thc clcmcntally resolved 

partial density of states to be measurcd. SXE 

also allows the direct measurement of hybrid 

states, of d-d excitations in transition nictal 

systems, and of changes in elcctronic structure 

during metal to non-metal transitions while the 

sample is in applied electric or magnctic ficlds. 

The BU group is using the spectrometer 

in the study of thrcc different classes of materials: 

wide band gap nitride semiconductors, organic 

superconductors, and transition metal oxides. 

During two runs in 1997, the BU group 

calibrated their SXE instrument and began study 

of each of these materials systems. As an example 

of thc first cxpcrimcnts, Figure 1-4 shows a series 

ofN K-emission spcctra from thcAIxGa, ,N alloy 

system. Owing to thc magnitude of the bandgap 

in thesc materials, thcy are ideal candidates for 

optoelectronic devices working in thc bluc/UV 

range of the elcctron~agnctic spectrum. The 

Binding Energy (eV) relative to AIN VBM 

spectra in Figure 1-4 arc thc result of t~ming the 

incident photon energy to just abovc thc N K 

absorption edge, thus creating holes on the N 

Is level, and measuring thc radiative dccay of 

thcsc holes. Dipole selection rules imply that 

the resulting spectra corrcspond to thc N 2p 

Figure 1-4: A series of N K-emission spectra from the 

AlxGa,~xN alloy system as a function of Al content x 

(O

Binding Energy (eV) relative to GaN VBM 

Figure 1-5: Same as Figure 1-1, except at greater 

binding energy (14-24 eV). 

essentially a symmetric opening up of the band gap. 

Unlike photoemission, there are no charging 

problems associated with such measurements, and 

the surfaces of the films were not atomically cleaned. 

A further illustration of the power of this 

spectroscopy is presented in Figure 1-5. Here the 

N K-emission spectra below the valence band are 

shown. Clearly visible at 19 eV is a well defined 

emission feature. This is direct observation of N 2p 

states hybridized with the Ga 3d shallow core level. 

The interatomic Ga 3d - N Is transition is forbidden, 

so the emission to the Is hole must arise from states 

with N 2p character. That the emission at 19 eV is 

due to these hybrid states is proven by the reduction 

of the emission with A1 content. 

Other experiments in the first runs explored the 

spatially resolved electronic structure of organic 

superconductors, and changes in d-d transitions in 

transition metal oxides during metal to non-metal 

transitions. W

Fermi Surface Mapping in Photoemisson 

P.D. Johnson, T. Valla, and A.V. Federov (BNL Physics Department) 

Photoemission represents one of the most powerh~l 

techniques for the stl~dy of the electronic structure of 

materials. It has seen widespread application to the study 

of metals, superconductors, surfkcs, thin films and, in 

its spin-resolved form, magnetic systems. In recent years, 

the development of higher energy resolution in this 

technique has allowed important contributions to be 

made to the field of high temperature superconductivit): 

Recently, a group in the Physics Department at RNI, 

has commissioned a new photoemission ficilitY based on 

the use of a Scicnta hemispherical analyzer. This 

instrument has the capability of measuring simultaneously 

the photoelectron's energy and angle of emission over a 

wide range of angles. An ~lltimate energy resolution of 5 

meV and an angular resolution of 50.21'are anticipated. 

The momentum resolution of the system is demonstrated 

in Figure I-6(a) whcrc we show the experimentally 

observed electronic bands of molybdenum dispersing 

through momentum space in the NH direction of the 

Rrillouin zone. The experitiicntal observations are 

compared with a tight-hinding calculation of the hand 

structure in the same region of the zone. The spectral 

density plot is obtained with incident photons of energy 

390 cV produced hy the soft X-ray undulntor on the Xl R 

beamline. The center of electron emission corresponds 

to an angle of 151' with respect to the surface normal. 

The experimental parallcl niomcnta, kil, arc dctcrmincd 

from kl = 0.5 I 23 (E ,,,, )" sin$ , whcrc represents the 

photoe/cctrorlh kinetic encrg,y ahovc the vacut~n~ lcrel and 

j the angle ofemission. Ry using higher incident photon 

energies, the variation in k of the final state as a function 

A 

of k is greatly reduced. Hoivcver, the qwstion arises as 

I, - 

to whether, at thcsc energies, it will still hc possihlc to 

ohserve the momentum dcpcndcncc of the electronic 

structure. That one can in fact do so is clcnr finm Figure 

I-6(a). An important point to note is that the 

experimental observations arc obtained with no changes 

in the voltages applied to the analyzer. One is simply 

"opening the shutter and taking a picture" of this 

particular section of the Brillouin zonc. In Figure I-6(b) 

Intensity (arb. units) 

Figure 1-6: (a) Spectral density plot recorded from a Mo(l10) surface along the NH section of the Brillouin 

zone. The incident photons from beamline XI B have an energy of 390 eV and the center angle of 

emission corresponds to 151'. The dotted lines indicate the results of a tight-binding calculation of the 

electronic structure in the same region of the zone. 

(b) Cuts through the spectral density plot of Figure I-6(a) to produce conventional angle-resolved 

photoemission spectra in the NH direction.

we show for comparison cuts through 

Figure I-6(a) at well defined spacings 

in angle in order to provide the 

traditional angle-resolved 

photoemission spectra. 

A spectral density plot, as shown 

in Figure I-6(a), allows us to examine 

in detail the Fermi surface of the 

material under investigation. This 

Fermi surface is defined by the points 

in momentum soace at which the 

I 

electronic bands intersect the Fermi 

level E,. Thus, the points labeled a 

and a' A Figure I-6(a) correspond to 

calipers on an ellipse centered at the 

N point of the Mo Fermi surface. An 

interesting observation is that the 

tunability of synchrotron radiation 

and the symmetry of the crystal allow 

the entire surface of such an ellipse 

to be mapped out without rotating 

the azimuth of the crystal. 

A measurement of the calipers, 

or spanning vectors, on the Fermi 

surface of a material is important for 

our understanding of the oscillatory 

exchange coupling that is observed in 

magnetic multilayers. Indeed, Figure 

1-7 ['I shows a calculation of the Fermi 

surface of bulk molybdenum and 

'igure 1-7: Calculated Fermi surface of Mo showing the 

;panning vectors appropriate to oscillatoy coupling in the 

110) direction from Ref. [I]. 

indicates the relevant spanning - 

. 

vectors for a multilayer grown in the (1 10) direction with spanningvector q from a to b would result in an oscillatory 

molybdenum as a spacer layer. For comparison, we period length, 2dq, 80% of that indicated ifi the 

indicate in Figure 1-7 the points a, a', and b corresponding theoretical calculation represented in Figure 1-7. 

to the same points in Figure I-6(a). Interestingly, the 

experimental determination in Figure I-6(a) of the [I] M.D. Stiles, Phys. Rev. B 48, 7238 (1993).

Surface Magnetic Ordering: A Spin-Polarized 

~hotoemis~ion Study of Thin Films of Gd 

P. Dowben and C. Waldfried (University of Nebraska), E. Vescovo (NSLS) 

Perhaps the most ren~arkable example of the 

uniqueness ofsurface magnctic properties is the condition 

of magnetically ordered surfaces at temperatures where 

the bulk material is paramagnetic. This is well 

documented for the rare-earth elements. An enhanced 

magnetization has also been proposed for chromium 

surfaccs, and the face centered iron phase. This property 

of the rare earth surfaces is a dramatic example of the 

different magnctic, as well as electronic, properties that 

exist at surfaccs, as notcd, for example, in the recently 

completed review chapter on the 

surface magnetism of the rare earth 

metals by PA. Dowhen et nl1'I. 

C. Waldfried and coworkers 

from the Dowben group have ~~tilized 

their previous expcrimcntal discovery 

of a localized surfacc state on the 

Gd(OOO1) surface to probe the origin 

of the different magnetic properties 

of the surfaces of both "unstraincd" 

and 4% expansively strained 

gadolinium films. Thcy find that the 

occupied bulk Gd 5dI6s bands for 

botli strained and unstrained Gd 

exhibit a Stoner-like exchange 

splitting consistent with theoryl2l. 

However, the strained Gd(OOO1) 

surface exhibits a mixt~~rc of Stoncr- 

like magnetism and spin-mixing 

behaviorl'l, with more rigid band 

ferromagnctisni than the unstraincd 

surface. 

During the past year a 

considerable amount of work focused 

on a dctailed study of the band 

structure of the 4%-strained 

Gd(0001) surface using spin 

polarized electron ~pectroscopyl'~. An 

important result of these 

measurements is that they show vcry 

clearly that the cxchangc splitting, and by cxtcnsion 

perhaps the magnetic couplins, is clcctroti wnvc vcctor 

dependent as seen in Figure M-1. Finite-tcnipcrnturc 

many-body band-struct~1rc-c;~1~~11~ltio1is~'~ predict this 

result, hut the extent of this wnvc vcctor dcpcndcncc is 

surprising. Consistent with the cn1i;lnccd magnetization 

of the surface, the exch;lngc splitting and wnvc vcctor 

dependence of the surface is different from the hull

Figure M-2: The logarithm of the reduced Curie temperature for strained 

gadolinium surface (open circles) and bulk (closed squares) are compared 

to unstrained gadolinium (closed circles) as a function of film thickness. 

A second very important result is that there is direct 

evidence that the surface Gd 5d exchange splitting, and 

thus the magnetic moment, is enhanced over the bulk 

particularly for the expansively strained Gd(OO0 1) surface. 

The observed surface Curie temperature of these films is 

370 K and is much higher than the bulk Curie 

temperature for expansively strained Gd(OOO1). Both of 

these temperatures are much higher than the generally 

accepted bulk Curie temperature of gadolinium of 293 

K. It is very clear that the surface plays the role of an 

"actor" not a "spectator" and will influence finite size 

scaling behavior in the ultra-thin film This is 

indicated in Figure M-2. W 

[I] PA. Dowben, D.N. McIlroy and Dongqi Li, "Surface 

Magnetism of the Rare Earth Metals", Handbook on the 

Physics and Chemistry of the Rare Earths, Edited by K.A. 

Gschneidner and Leroy Eyring, (Chapt. 159) 24, 1, 

(1996). 

[2] W. Nolting, T. Dambeck and G. Borstel, Z. Phys. 

Rev. B 94, 409, (1994). 

[3] C. Waldfried, D. Welipitiya, T. McAvoy, E. Vescovo 

and PA. Dowben, "Wave Vector Dependent Exchange 

Splitting in a Local Moment System", submitted to Phys. 

Rev. Lett. 

C. Waldfried, T. McAvoy, D. Welipitiya, P.A. 

Dowben, and E. Vescovo, "The Influence of Enhanced 

Surface Magnetism on Finite Size Scaling", submitted to 

Europhys. Lett.

First Observation of Half-Metallic Behavior: 

A Spin-Polarized Photoemission Study of 

Thin Films of La 0.7 Sr 0.3 MnO, 

J.-H. Park, E. Vescovo, and H.-J. Kim (NSLS) 

s mentioned above, a considerable amount of 

experimental work at U5UA during 1997 was devoted 

to the study of the electronic structure of a thin film of 

La,,,Sr,,,,MnO,. This material belongs to the class of 

manganese perovskites, derived from the 

antiferromagnetic insulating parent-compound LaMn?, 

by partial substitution of La with Sr atoms. As is \vcll 

known, with increasing temperature this material 

undergoes a complex phase transition from a metallic- 

ferromagnetic phase at low temperatures to an insulnting- 

paramagnetic phase at high temperature (T,. 350 K). 

This link between metallic character and ferromagnetic 

behavior, as opposed to insulating and 

antiferrornagnetism, seems to be a quite general 

characteristic of transition metal oxides ''1 and has heen 

explained, at least in some cases, by the so-called doublc 

exchange mechanisn~~'~. According to this model, 

substituting divalent Sr atoms for trivalent La ones forces 

a corresponding number of Mn ions to become 

tetravalent: the system is now a mixed-valent con~pound 

1 .O 0.5 E~ 

Binding Energy (eV) 

in which both Mn" (as in 1,aMnO.J and Mn" ions arc 

present. The conduction can then be sustained (at no 

cost, in the ferromagnetic system) by clcctron hopping 

from a Mn3+ to a neighl>oring Mn"' site (the two 

configurations Mn"-0' -Mn"+ and Mn"-0' -Mn" being 

obviously degenerate). This transport mcch;lnism is 

mediated by the 0' ions, which permit n "doublc 

exchange" in which an electron is exchanged bctwccn a 

3dorhital ofthc Mn'+ ion and un 0 2p electron, while ;~t 

the same time another clcctron is cxc1i;lnged from the 0 

2/, to the Mn" ions. However, owing to the strong onsire 

Mn exchange intcr;~ction, this hopping is allowed only 

if the two ncighhoring Mn ions are ferroniagnctically 

aligned: i.e. the system can become mct;~llic only if it also 

ordered ferromagnctically A very important conscqucncc 

of this conduction mcchanisrn is that this systcm sliould 

then have charge-carriers all with the same (majority) 

spins, i.e. it should be a perfect half-mctnllic systcm 

displaying 100% spin-polnrization at the Fcrmi Icvcl. In 

Figure M-3, the metal-to-insulntor transition of 

Figure M-3: The metal-to- 

insulator transition of the 

La,,Sr,,MnO, thin film is clearly 

displayed by the change in the 

density-of-state at the Fermi 

level. At low temperature (open 

symbols) the system is metallic 

while at high temperature 

(closed symbols) it becomes 

insulating. The valence band 

spectrum is shown on a larger 

binding energy scale in the 

inset (continuous line).

Lao,,Sro,,MnO, is clearly displayed: the 

density-of-state at the Fermi level disappears 

with increasing temperature. Figure M-4 

instead shows the spin-resolved spectrum of 

the valence band in a region very close to 

the Fermi level when the system is kept at 

low temperature, i.e. in its ferromagnetic- 

metallic phase. Unambiguously, the 

predicted 100% spin-polarization is observed 

close to the Fermi level. The proof of the 

existence of half-metallic is not 

only important from the fundamental point 

of view but also has important implications 

for technological applications. Indeed, the 

realization of an half-metallic system also 

implies, for example, the realization of a 

100% spin-polarized electron source or the 

realization of a perfect spin-filter. For this 

reason, laboratories all over the world are 

currently testing the magnetic properties of 

these types of materials. In this connection, 

the very surface sensitive measurements 

performed at U5UA on a thin-film surface 

prepared in-situ represent the first 

measurements available of this kind and do 

show a largely distinct magnetic behavior on 

the surface of these materials as compared 

to their known bulk propertie~[~]. 

. 

[I] D.I. Khomskii, G.A. Sawatzky, Solid 

State Comm. 102, 87 (1997). 

[2] C. Zener, Phys. Rev. 81, 440 (1 95 1). 

[3] J.-H. Park, E. Vescovo, H.-J. Kim, C. 

Kwon, R. Ramesh, and T. Venkatesan, 

"Observation of a Half-Metallic 

Ferromagnet", Nature (in press, 1997). 

[4] J.-H. Park, E. Vescovo, H.-J. Kim, C. 

Kwon, R. Ramesh, and T. Venkatesan, 

"Novel Magnetic Properties at Surface 

Boundary of a Half-Metallic Ferromagnet 

Manganese Perovskite", submitted to 

Science. 

3 2 1 EF 


Figure M-4: Contemporary to the metal-to-insulator 

transition shown in Figure M-3, the La,,Sr,,MnO, system 

undergoes a ferromagnetic-to-paramagnetic. Below the 

Curie temperature the thin film shows a very good 

magnetic remanence (see inset). The spin-resolved 

spectra (closed up-triangles: majority spin; open down- 

triangles: minority spin) of the region near to the Fermi 

level clearly demonstrate that charge-carriers are totally 

of majority-spin character, i.e.: a 1000/0 spin-polarization 

is observed. This result represents the first experimental 

evidence of the existence of an half-metallic system.

The c-axis Optical Response of Y l-~ Ca x Ba,Cu 3 0 7-6 Single 

Crystals Studied by Far Infrared Ellipsometry 

C. Bernhard, R. Henn, A. Wittlin, W. Konig, and M. Cardona 

(Max-Planck-lnstitut fur Festkorperforschung) 

The incohcrcnt electronic c-axis conductivity measurements on crystals with ac-faces ;IS small ;IS 1 m0.3 

ocC'(~,T) of the cuprate high-Tc superconductors has mni2. The ellipsometry tcchniquc provides significant 

attracted considerable attention. The most peculiar feature advanragcs over conventional rcflcction mcthods. 

is the gap-like suppression of the normal statc o,,''(t~,T) Ellipsometry is self normalizing and docs nor require n 

in the far infiarcd (FIR) rcgimc which has recently bcen reference sample. 7l1c real- and the im1gin:lr.y part of tllc 

observcd in undcrdopcd YB~,CLI,~O~-~ (Y- 1 23)1'.21, dielectric function arc obtained directly without n 

YBa,Cu40, and possibly also in La, --, SrlCu04 I4.'l. This Kramers-Kronig trnnshrmation. 

observation has raiscd thc question ofwhether the unusual 

propcrtics of thc FIR c-axis conductivity are related to 

Figure M-5 sho\vs 0, ( ' I ) for 

Y ,,,,, Ca,, ,,Ba,Cu,O.. , in ordcr of incrcming oxygcn 

the pscudogap which dcpletcs the low energy spin- and content and doping. Figure M-6 sho\vs the darn for Cacharge 

excitations of the CuO, planes!" rather than to free Y-123 which is more fully oxygcn;ltcd at a h' 'IVC'II 

the insulating rocksalt laycrs which separate the metallic doping statc. The oxygen deficiency of the cryst;lls c;ln 

CuO, planes acting likc "blocking layers"171. In the former he estimated from the spectral \vcight of tlic pliono~~ ~iiod~ 

case CJ,'"(W,T) should evolve as a function of the holc at 620 cm-' which increases with the oxygcn deficiency 

doping of the CuO, planes, in analogy to the pseudogap of the crystal since it involves the vihrntion of an apex 

which occurs only for ~~ndcrdoped samples and disappears oxygcn next to an empty clinin fr;~gmcntl'-'l. 'I'licrc arc 

around optimum doping161. In the latter case the five morc IR-active modes supcrimposcd on the clcctronic 

anomalous features ~~cJ,~'"(w,T) should depcnd critically background which will not he further discussed hcrc. 

on the structural and electronic details of the "blocking From Figures M-5 and M-6 it is evident that a gnplayc~s"'~. 

In particular, for Y-123 the CuO chains should likc suppression of O,~'"(W,'T) in the normnl st;lte occurs 

have a pronounced influence since they bccome metallic only for the underdoped samples. 'I'hc normal stntc gap 

upon oxygenation and rcducc the effectiveness of the in 0,~"(t0,7') disappears around optimum doping. In the 

"blocliing laycr". 

overdoped regime oIQc'(~),T) exhihits ;I riict;~llic '1.- and 

In ordcr to rcsolvc this question we have performed a-dependence. Thc oxygcn contcnt of thc Ci10 ch;tins 

ellipsometric nicasurcmcnts of the FIR c-axis conductivity and the related clcctronic propcrtics of the "blocking 

on Yl-xCalBa,Cu,0,~6 (Y,Ca- 123) single crystals for x=O layers" do not affcct the characteristic 'I- and 0)and 

x=0.14 and variable oxygcn deficiency 61". The partial dependence but merely affkt the ahsolute values of 

substitution of Y3' by Ca" introduces extra hole carricrs CJ,~'"(CI),T). This finding implies that pscudognp 

into the CuO, plancs in addition to thosc that are correlations which dcplctc the low cncrgy spin- and ch;~rgc 

transferred from the CuO chains as controlled by the excitations of the CuO, pl;~ncsi"! may c;~usc the gap-liltc 

oxygcn content!'". This enables us to access almost the suppression of oILc'(~,T) and the confinement of the 

entire doping range from underdopcd to strongly charge carriers in the norm:ll st;~tc. 

ovcrdopcd. Furthcrmorc, the opposing effects of holc In the ovcrdopcd rcgimc this confinement is 

doping due to Ca-substitution and hole depletion due to gradually relaxed while the SC stntc deteriorates. Both 

a deoxygcnation of the CuO chains allows us to study T and the SC cncrgy gap 2A (as estimated from the 

samples with a comparable doping statc of the CuO, onset of the loss of spectral wight in the SC stutc wlicn 

planes but a significantly different oxygcn content and the carricrs condense into a delta function ;~t zero 

thus electronic propertics of the CuO chains. 

frequency) arc suppressed. In addition ;I growing fraction 

The ellipsometry measurements have bcen of the quasi-particles remains unpaired in the SC statc 

perforrncd at thc U4IR bcarnline of the National possibly due to strong pair-hrcnlting eflcctslx,"l. 'I'his 

Synchrotron Light Source (NSLS) at Rrookhaven raises the question \vhethcr the pscudogap and the 

National Laboratory (BNL), using a home-built setup confinement are necesmry prcl-cquisitcs for the occurrence 

attached to a Nicolet Fourier Spcctron~eterl~."'l. The high 

brilliance of the synchrotron allows us to perform accurate 

of high-T' superconductivity i11 the cupratcs.

OVERDOPED 

Tc=63 K; 60.05 - 

- 

.-----. 

300 K 

200 K ' 

Figure M-5: The real part of the FIR c-axis conductivity o,,(o,T) of the Yo,,,Cao,,,Ba,Cu,O,, single crystals 

with variable oxygen deficiency d and doping of a) Fu0.6, Tc=67 K (underdoped); b) 6~0.35, Tc=82 K 

(underdoped); c) Fu0.3, Tc=Tcmax=85 K (optimally doped); d) FuO.2, Tc=81 K (overdoped); and e,f) 6~0.05, 

Tc=63 K (overdoped). The data are shown in the SC state by the red solid lines, in the normal state just 

above Tc by the blue dotted lines, at intermediate temperatures by the green dashed lines and at room 

temperature by the black solid lines.

-I----- 

OVERDOPED 

T_=89 K; &0 

Figure M-6: The real part of the FIR c-axis conductivity o&,T) of YBa,Cu,O,., single crystals for 

variable oxygen deficiency and doping of a) 6~0.55, Tc=53 K (underdoped); b) 6~0.2, T,=88 K 

(underdoped); c) 6~0.1, Tc=Tc,max=92 K (optimally doped); and d) 6u0, Tc=89 K (overdoped). The 

data are shown in the SC state by the red solid lines, in the normal state just above Tc by the blue 

dotted lines, at intermediate temperatures by the green dashed lines and at room temperature by 

the black solid lines.

Acknowledgements. We are indebted to G.I? Williams and L. Carrfor support at the U4IR beamline of the NSLS 

and acknowledge D. Biihmefor technical help. We thank M. Kliiser, 7: Wolfand C. 7: Lin for providing the crystals. 

[I] C.C. Homes et al, Phys. Rev. Lett. 71, 1645 (1993). 

[2] J. Schiitzmann etal, Phys. Rev. B52, 13665 (1995). 

[3] D.N. Basov etal., Phys. Rev. B 50, 351 1 (1994). 

[4] K. Tamasaku et al., Phys. Rev. Lett. 72, 3088 (1 994). 

[5] R. Henn et al., to be published in Thin Solid Films; R. Henn et al, Phys. Rev. B 56, 6295 (1997). 

[6] J.W. Loram et al, Phys. Rev. Lett. 71, 1740 (1993); A.G. Loesser et al., Science 273, 325 (1996); G.V.M. 

Williams et a/., Phys. Rev. Lett. 78, 721 (1997). 

[7] A.A. Abrikosov, Phys. Rev. B 52 , 7026 (1995); Physics C 258, 53 (1996); W.A. Atkinson and J.l? Carbotte, 

Phys. Rev. B 55, 3230 (1997). 

[8] C. Bernhard et dl., to be published in Phys. Rev. Lett. 

[9] J.L. Tallon et al., Phys. Rev. B51, 1291 1 (1995). 

[lo] J. Kircher et al, 1. Opt. Soc. Am. B14, 705 (1997). 

[l 11 C. Bernhard et al, Phys. Rev. Lett. 77, 2304 (1996).

Surface Alloys: An Auger Photoelectron Coincidence 

Spectroscopy Study 

R.A. Bartynski, and Q. Qian (Rutgers University), and S.L. Hulbert (NSLS) 

The VUV Ring has seen considerable utilization 

by a number of novel applications including Auger- 

photoelectron coincidence spectroscopy (APECS). 111 tliis 

adaptation of photoelectron spectroscopy both the core 

photoclectron and the Auger electron associated with a 

given pliotoexcitation/decay event are dctcctcd in time 

coincidcncc. Exatnining the photoemission spectrum 

with tliis additional level of discriminntion results in 

higher surface sensitivity and enables site-specific 

electronic structure studies while eliminating secondary 

electron background and lifetime broadening. 

Kinetic Energy (eV) 

Perhaps most exciting rcsults are in the ficld of 

surface alloys. Wc haw successfr~lly m:dc the first dircct 

rncasurcrnent of valcncc band energy shifts in n surface 

alloy: Ag/Cu(lOO). In recent years, there hx bccn 

considcrahlc theoretical and expcrimentnl interest in 

surfke alloys (bimetallic systems tht intermix only in 

the first atomic I:qw) owing to their novcl clcctronic, 

chemical, and ningnetic psopcsties. First principles 

electronic structure calculntions suggest that band 

narro~ving and a systcmntic shift (;IS a f~~nctioti of host) 

in tlic valence levels of tlic minority species Icnd to the 

Figure M-7: Auger photoelectron coincidence spectroscopy (APECS) Ag N,VV Auger spectra 

from Ag(100) and from the Ag/Cu(100) system for three Ag coverages as indicated. These 

spectra were taken in time coincidence with Ag 4p,, photoelectrons excited with 2OOeV 

photons.

unusual physical properties of these systems. Up 

until now, experimental work has focused on 

structural aspects, particularly STM 

measurements exploring phase formation upon 

intermixing at the surface. Measurements of the 

electronic structure using conventional 

photoelectron spectroscopy are extremely difficult 

because the signal - from the minority metal 

typically is weak and often overlaps spectral 

features of the substrate. 

Our primary result is summarized in Figure 

M-7. Here, APECS spectra of the Ag N,W 

Auger transition from Ag(100) are compared to 

that of the AgICu(100) system for several Ag 

coverages. As is clear from the figure, the peak in 

the coincidence Auger spectrum shifts to-higher 

kinetic energy for low Ag concentrations. This 

shows that the Ag d-levels shift closer to the Fermi 

level as compared to Ag metal. STM studies 

indicate that for coverages in the 0.1 monolayer 

(ML) range, Ag forms a random substitutional 

alloy in the Cu(100) surface. The calculations 

predict that in this phase, the centroid of the Ag 

d-band shifts + 0.70 eVaway from the Fermi level. 

The origin of the difference between our 

experimental results and the theory is not yet clear, 

however the shifts can be understood in terms of 

relative electron density and the calculations were 

performed for the closed packed surface, while 

our experiments examined the more open (1 00) 

surface. Upcoming investigations of PtICu(100) 

and PtlAg(100) should prove most interesting. 

(b) 

b 

b I 

Ag N3VV 

Coincidence Spectrum 

Ag 4p3,, Fixed 

ho = 200 eV 

o Coincidence 

- Smooth 

Background Subtracted 

o Coincidence 

I d8 Multiplet 

o Coincidence 

Multiplet Gaussians 

.30 35 40 45 50 55 


Figure M-8: (a) Ag N,,W coincidence Auger spectrum 

(circles) of the Ag(100) surface taken in time coincidence 

with Ag 4p3,, photoelectrons excited with 200eV 

photons. Digital smooth (solid line), multi-electron 

background (dotted line) and atomic-like a8 multiplets 

(vertical solid bars) are shown. (b) Background- 

subtracted (from (a)) Ag N,,3VV coincidence Auger 

spectrum of the Ag(100) surface. (c) same as (b) except 

CP multiplets are Gaussian-broadened. The sum of the 

broadened multiplets is shown (solid line, labeled 

"Correlated decay").

To better understand the influence of 

alloying on the electronic structure of the 

minority component, we have also performed 

detailed studies of the Ag 4p core levels and 

the associated N,,,W Auger spectra from the 

single crystal Ag(100) surface. It is well known 

that the shallow p-levels of the late transition 

metals have very broad and ill-defined spectral 

line shapes. Owing to strong overlap with the 

4d bands, the shallow 4~ levels of Ag have a 

very short lifetime and hence appear as broad 

(+5 eV wide) features in photoemission 

spectra. This width is folded into the 

conventional Auger spectrum. By measuring 

Ag N,,,W Auger electrons in coincidence 

with Ag 4p photoelectrons of a particular 

kinetic energy, we have eliminated this 

broadening - and revealed the intrinsic lineshape 

of the Auger transition. These coincidence 

Ag N,W Auger spectra are shown in Figure 

M-8. The majority of the emission is 

accounted for by an atomic-like d8 multiplet, 

but there is a significant band-like component. 

A comparison of the relative spectral weight 

contained in each component indicates 

. 

that 

the band-like part is larger than is observed in 

conventional M,,,W Auger spectra and also 

larger than is anticipated based on the band 

width and correlation energies of Ag. 

64 66 68 70 72 


Figure M-9: (a) Ti 3p core level spectrum from the clean, 

stoichiometric Ti0,(110) surface taken in time 

coincidence with Ti M W Auger electrons. The Ti4+ main 

peak, and shoulders assigned to Ti3+ and Ti2+ oxidation 

states, associated primarily with surface oxygen 

vacancies and step edges, respectively, are labeled. (b) 

same as (a), but acquired after - 0.2 monolayer (ML) of 

Ag is adsorbed on the surface.

Large Value of the Electron-Phonon Coupling Parameter 

b1.15 and the Possibility of Surface superconductivity at 

the Be(0001) Surface 

T. Balasubramanian and E. Jensen (Brandeis University) 

X.L. Wu and S.L. Hulbert (NSLS) 

The electronic density of states (DOS) at the Fermi 

level (E,) at the Be(0001) surface is about four times larger 

than in the bulk"]. The E, DOS is an important 

parameter for describing many electronic processes. 

Anomalously large surface core level shiftsL2], and giant 

surface Friedel oscillation^[^] have been observed on this 

surface, and attributed to the large surface to bulk E, 

DOS ratio. Electron phonon coupling should also be 

enhanced. In a typical electron-phonon interaction event, 

an electron scatters from one state to another with the 

emission or absorption of a phonon. By simple Fermi 

golden rule arguments, one expects the probability for 

this interaction to be proportional to the density of states 

into which the electron can scatter. Phonon and thermal 

energies are small on the scale of electronic energies and 

the final state energy is near to E,, so the coupling is 

proportional to the electronic density of states at E,. The 

strength of the electron-phonon interaction is 

conventionally measured by the dimensionless parameter 

h, called the mass enhancement or coupling parameter. 

Accordingly, one should expect h at the Be(0001) surface 

to be near unity, four times larger than the bulk value 

h,=0.24. 

It has been shown that angle resolved photoemission 

(ARP) can be used to determine hs for crystalline metal 

The basic idea is that, under proper conditions, 

the observed width of a surface state peak is equal to h l~, 

where T is the lifetime of the surface state hole excitation. 

Since virtually all of the temperature dependence of T is 

in the phonon contribution, a measurement of the 

temperature dependence of the surface state width is 

effectively a measurement of the temperature dependence 

of the phonon contribution to the hole lifetime. At high 

temperatures and small hole energies the temperature 

dependence of the phonon contribution to the inverse 

hole lifetime is given by h/z =2 nhkT. In this limit, h is 

just 2nk times the slope of the peak width vs. temperature 

curve, and is easily measured. 

We have used ARP to determine hS at the Be(0001) 

surface and find that As= 1.15, more than four times larger 

2.0 1.5 1.0 0.5 0.0 4 

BINDING ENERGY [eV] 

Figure M-10: Surface state spectra at several 

temperatures. The momentum is 0.89 A-l, 

the hole energy is 0.35 eV, and the photon 

energy is 15 eV. The open circles are the 

experimental data. Typically there are 1500 

counts in the peak. The line is a fit to a 

function of the form lorentzian plus constant 

times the fermi distribution. Temperatures (T) 

and widths (W) derived from the fit are as 

indicated.

than A,,. The data and analysis are presented in the figure 

below. 

It is common for large values of h to he associated 

with high superconducting T,:'s, especially in niatcrinls 

such as Be with large phonon energies. If the surface is 

considered as a thin film with high h on a thick substrate 

with low h, the proximity effect would destroy any 

observable interesting effects. However, it was shown by 

Suhl, Matthias, and WalkeriS' that different branches of 

the Ferlni surface - for which surface and bulk statcs 

qualify - could have different superconducting energy 

gaps. In the limit of a semi-infinite solid the two branches 

are essentially uncoupled and the surface states are allowed 

superconduct independent of the bulk. Application of 

the McMillan formida using bulk phonons to estimate 

the supcrconducting transition tenipcrature yields 70K 

for the surface transition temperature. 

----Straight line fit : A = 1.06 

----- Debye Model fit : A: = 1.25 

J 

0 100 200 300 400 500 600 700 800 900 

TEMPERATURE [K] 

Figure M-11 : Surface state widths from fits like those shown 

in Figure M-10 vs. temperature. These data include two 

full cycles from room temperature to 800K and back to 

room temperature. The error bars on the data are 

statistical uncertainties from the fits. The open circles are 

for increasing temperature and the filled circles are for 

decreasing temperature. This analysis assumes that all of 

the temperature dependence of the widths comes from 

phonon creation/annihilation. In the limit of high 

temperatures, not quite realized for these data, h is 

proportional to the derivative of the width with respect to 

temperaturen; a more accurate analysis results from a fit 

to the Debye model. 

Impuriticsldcfccts will likely play n morc important 

role in dcstahilizing this system than they do in 

homogeneous superconductors. The prol,lcm is that tlic 

impurities scatter surface stntcs into bull< stntcs, the one 

electron cigenstates hccon~c linear combin:~tions of surf~cc 

and bulk states, and tlic pairing interaction is wcragcd 

over surfacc and hulk. Sincc the interaction in the bull< 

is weak, any averaging will quicl

Characterizing Interfacial Magnetic Roughness 

I. Freeland and Y. ldzerda (NRL) 

Industrial production of magnetic devices and 

media (computer hard disks, readlwrite heads, magnetic 

memory, etc.) is undergoing an explosion in size similar 

to that experienced by the semiconductor industry a 

decade ago. However, many effects that are not well 

understood plague the behavior of these systems. One of 

essential importance is the disorder of magnetic moments 

at the interface (i.e. magnetic roughness). Since these 

magnetic devices consist of thin layers (+ 10.' cm) of 

ferromagnetic (FM) and non-magnetic (NM) materials, 

roughness at the boundary between the FM and NM 

materials can dramatically alter the magnetic behavior. 

Recently our group (John Freeland, Varoujan Chakarian, 

Konrad Bussmann, Yves Idzerda, and Chi-Chang Kao) 

at the NRLINSLS Magnetic Circular Dichroism Facility 

(located at beamline U4B of the NSLS) has been studying 

the interdependence of magnetic and chemical 

interfaces. 

We find that the magnetic and chemical roughnesses 

of a NMIFM interface are distinctly different. This 

means that to obtain a full picture of how roughness 

influences the magnetic properties, one must obtain 

information concerning both the magnetic and chemical 

interfaces. The formalism for the determination of the 

nature of chemical interfaces and surfaces using specular 

and off specular (diffuse) scattering is a well established 

field, but only recently has it become possible to directly 

probe the magnetic interface. To probe information about 

a magnetic interface one needs a significant magnetic 

scattering signal. One way of providing this is through 

the resonant enhancement of the magnetic and chemical 

scattering when an incident circular polarized photon is 

tuned to an absorption edge, known as x-ray resonant 

magnetic scattering (XRMS). Utilization of a circular 

polarized photon, like its absorption counterpart 

Magnetic Circular Dichroism (MCD), generates the 

magnetic scattering component. By measuring sample 

rocking curves at the L, absorption edge, we can extract 

information concerning not only the chemical but also 

the magnetic interface. 

Figure M-12: Sample rocking curve measured at the Co L, (778 eV) for chemical 

and magnetic contributions vs. q,. This scan was taken at a detector angle 20 of 

90. Notice how the half width if the magnetic diffuse (GM) is smaller than that of 

the chemical diffuse (GC) indicating a longer correlation length, x, for the magnetic 

interface.

To explore how an NM/FM interface varies with 

roughness we utilized a series of CoFc thin films whcre 

an increasing chemical roughncss was induced through 

the growth process. Figure M-12 shows the chen~ical 

and the magnctic contributions to a sample rocking 

(diffuse) scan measured at the Co L, edge. From the 

analysis of these rocking curves we find a distinctly 

diffcrcnt behavior of both perpendicular (s) and in-pl.~ne 

(x) roughness for the chemical vs. magnetic interfaces. 

To test the interdependence of the chemical and magnetic 

roughness we have measured a series of sample5 with 

varying chemical roughness, as determined by Atomic 

Force Microscopy (AFM), whcre the roughness variation 

is generated by a thickness variation in Cu growth 

5 10 15 20 25 30 

AFM Roughness (A) 

Figure M-13: Perpendicular (s) and in-plane (x) roughness 

parameters derived from the diffuse scattering data. Top 

panel: chemical and magnetic rms roughness. Bottom panel: 

chemical and magnetic correlation lengths. 

template prior to magnetic multil;lycr dcpositioti. As seeti 

in Figure M-13, the magnetic roughness in this series of 

samples typically -20-30%) less than the chemical 

roughness. The same is seen for the behavior of the 

chemical vs. ningnctic correlation length (bottom panel 

of Figure M-13). This indicates that tlic magnetic 

interf'lce is typically much smoother than the clicmical 

interf'~ce both perpendicular and in tlic plane of the film. 

These results illustrate clearly that one cannot understand 

the influence of roughness by only explorit~g the chemical 

interface. Not all magnetic properties arc affected in the 

same way by interfacial disorder, so only by Ixlving tlic 

con~plete picture can we hegin to obtain an 

understanding.

In addition to our work 

studying NMIFM interfaces, we are 

also trying to better our 

understanding of diffuse XRMS 

technique. Due the dramatic 

changes in the scattered intensity 

near the absorption edge, we 

undertook a study of the diffuse 

intensity not only as a function of 

qx but also energy of the incident 

photon. Figure M-14 shows the 

results of such a measurement. 

Notice in particular how by only 

changing the incident photon by a 

few eV the shape of the diffuse 

intensity (both magnetic and 

chemical) can be altered 

significantly. While these resonant 

changes appear very different they 

contain the same information 

concerning the interface. Analysis 

of this data will not only further our 

understanding of this technique, 

but will also provide a testing 

ground for theories of diffuse 

XRMS. 

Our current work has brought 

our understanding to a point where 

we stand on the threshold of being 

able to explore a wide variety of 

problems related to magnetic 

heterostructures of extreme interest 

to many facets of the magnetism 

community. . 

--- Chemical 

Figure M-14: Diffuse intensity as a function of qx and 

incident photon energy. The black line shows the cut along 

qx at the Co L, edge that yields the data in Figure M-12.

Resonant Inelastic Scattering Studies of 4f rare Earth 

Compounds 

F. Bartolome, J.M. Tonnerre, L. Seve, and D. Raoux (CNRS, France), 

J. Chabo and L.M. Garcia (Instituto de Ciencia de Materiales de Aragon, 

Spain), d Krisch (ESRF), and C.-C. Kao (NSLS) 

A systematic study of the 2p3,2-3d,,, or 2pii2-4d,,, 

resonant inelastic scattering of 4f rarc carth conlpounds 

(R = Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) was carried 

out by Bartolonic et nl. An E2 (2p (4f) quadrupolar 

absorption channel was observed for all the conipounds 

studied. Energy separation between the dominant El 

(2p (5d) dipole absorption energy and the weak E2 

absorption energy was also measured systematically. A 

double-peaked preedgc feature was observed for light rarc 

earth ions, and was intcrprctcd as two intermediate states 

corresponding to the excitations of the two possible spins 

of the excited photoelectron. Detailed comparison was 

also made with corresponding x-ray magnetic circular 

dichroisni ( XMCD ) spectra to show that the origin of 

the low energy XMCD effect from all rarc earth ions is 

due to E2 ahsorption channel, and that the sign change 

in the XMCD signal from light rarc carth ions to Iicavy 

rare earth ions is due to the doulc-peaked prc-edge 

absorption feature in light rare earth ions. . 

Resonant Inelastic Scattering Study of Nd,CuO, 

J.P. Hill, C.-C. Kao, W.A.C. Caliebe (BNL), M. Mastubara, A Kotani (ISSP, Tokyo), 

J.L. Peng and R.L. Greene (University of Maryland, College Park) 

Resonant inelastic scattering study of Nd,CuO',, 

the parent compound of the electron doped high 

temperature superconductor Nd, hCelCuO,,, at the Cu 

K absorption edge was reportcdl'l. Resonant 

enhancement of the charge transfer excitations, similar 

to the observation in NiO, was observed. An Anderson 

impurity model which includes both the intra-atomic 

Coulomb interactions and Cu(3d)-0(2p) interatomic 

hybridization, was used to interpret the data. The model 

calculations agree well with both the observed energy 

loss and the excitation energy dependence of the 

scattering intensity. And the observed energy 1055 of 6eV 

. 

is assigned to excitation from the ground state to tlic antibonding 

state of the CuO, cluster. There is also indication 

that non-local effects are important in the interpretation 

of these spectra. 

[I] F. Bartolome, J.M. Tonncrrc, I.. Scvc, D. Iiaoux, 

J. Chaboy, L.M. Garcia, M. Krisch, C.-C. Kao, 

"Identification ofQuadrupolar Excitation Channels at the 

L 111 ,, Edge of Rare Earth Compounds"; P/y. Ih. I,PU. 

79, 3775 (1 997). 

[2] Hill ct nl., submitted IYy. Rm Lett.

Bond-length Distortions in Strained Semiconductor Alloys 

J.C. Woicik (NIST) 

When a macroscopic body is acted upon by small In their pioneering study, Mikkelson and Boy~e[~] 

external forces, its deformations are accurately described used EXAFS to measure the bond lengths in bulk 

by the theory of elasticity[']. Despite the maturity of this Ga,-xIn&s alloys. They found that, instead of following 

branch of theoretical physics, the microscopic distortions 

I bond length and bond angle I which govern the 

macroscopic behavior of the body are, in general, not 

well understood, particularly from an experimental point 

the virtual-crystal approximation (VCA), 

of view. Because the macroscopic-strain state of the In-As and Ga-As bond lengths maintain two 

semiconductor layers can be accurately determined by chemically distinct values. Although these distinct values 

bulk-sensitive techniques such as x-ray diffraction, do vary linearly with alloy composition, this variation is 

strained-layer semiconductors offer a unique vehicle with only about a quarter (- 0.04 A) of the natural bond-length 

which to study these microscopic distortions difference between bulk Ids (roIds = 2.623 A) and bulk 

quantitatively. 

GaAs (roGAs = 2.448 A). Using the accurate data of 

In order to address the issue of bond-length strain, Mikkelson and Boycel31, the In-As and Ga-As bond 

we121 have performed high-resolution extended x-ray lengths in a bulk (cubic) Ga,-xInxAs alloy with In content 

absorption fine structure (EXAFS) measurments at the 22% are rids = 2.596 A, and r,$ = 2.455 A, respectively. 

In-K absorption edge (27,940 eV) on a well characterized, 

buried, 213 A Gao,,,Ino,2,As layer grown coherently on 

The In-As bond length measured in the strained layer, 

tIds = 2.581 f 0.004 A, is significantly shorter than this 

GaAs(001). Figure M-15 shows the EXAFS from the value. In fact, it is even shorter than the In-As bond 

strained layer. These data were recorded at beamline 

X18B using a Si(ll1) 

channel-cut monochromator 

and a 13 element Ge solidstate 

detector set to monitor 

length measured by Mikkelson and Boycel31 in the dilutethe 

In-Ka fluorescence yield. 

Also shown is the EXAFS 

from bulk Ids, recorded in 

0.2 

transmission. Both are 

plotted with their Fourier- 

0.0 

filtered first-shell 

contributions, which 

correspond to the In-As bond 

lengths. 

-0.2 

n 0.2 

0's 

To obtain quantitative 

information, the data from 2 

the layer were fit by the 

function kx(k) using the 

phase and amplitude 

functions derived from the 

bulk InAs standard. The fit 

determines r'InAs = 2.581 + 

0.004 A. Because the bond 

length in bulk InAs is 2.623 

A, the In-As bond length in 

the strained layer is found 

contracted 0.042 f. 0.004 i% 

relative to the In-As bond 

length in bulk InAs. 

0.0 

w 

X 

Y -0.2 

0.2 

0.0 

-0.2 

Figure M-15. 

4 6 8 10 12 

k (K1) 

14

alloy limit, r,,,A, = 2.588 A for x -+ 0; consequently, it 

must reflect the external comprcssivc strain imposed on 

the layer by the substrate: Ar = - 0.01 5 + 0.004 A. 

Because the latticc constant of InAs is 7% larger 

than the lattice constant of GaAs, pseudomorphic growth 

of a Ga,-xInxAs alloy on GaAs(001) results in a laycr that 

is compressed bilaterally within the (001) plane of the 

substrate and Poisson expanded uniaxially along thc [OOI] 

growth direction. From macroscopic-elastic thcory141, the 

fractional strain of the film parallel to the interface, E,, = 

( a,, - a, )/a,, is related to the fractional strain of the film 

perpendicular to the interface, E, = ( a, - a, )/a,, through 

the elastic constants c,, and c,, of thc film, its cubic latticc 

constant a,, and the coherency condition a,, = a ,,a,

alloys on GaAs(001). The calculation was performed by relaxing the atoms within sixteen-bond Ga4JnjAs clusters (j 

= 0,1,2,3,4) embedded in virtual-crystal media. The bond lengths were calculated as a function of medium composition 

x and then statistically averaged. The Keating valence-force generalized for the pseudobinary alloy, was used 

to model the interactions within the clusters: 

The as's are the two-body radial-force constants, and the Ps,c's are the three-body angular-force constants. The 

rs's are the bond vectors between atoms with equilibrium distance rho; i.e., the natural In-As and Ga- As bond lengths. 

Figure M- 16 shows the resulting statistically-averaged In-As and Ga-As bond lengths for cubic clusters (dashed lines) 

and for clusters that have been tetragonally distorted in accordance with Eq. 1 (solid lines). The results of the 

calculation are in excellent agreement with the bulk measurements of Mikkelson and B0yce[~1 and the results of the 

present study, thereby confirming the uniform nature of the bond- length distortion. H 

[I] L.D. Landau and E.M. Lifshitz, Theory of Elasticity (Pergamon Press, Oxford, 1970). 

[2] J.C. Woicik, J.G. Pellegrino, B. Steiner, K.E. Miyano, S.G. Bompadre, L.B.Sorensen, T.-L. Lee, and 

S. Khalid, Phys. Rev. Lett. 79, 5026 (1 997). 

[3] 

[4] 

[5] 

[6] 

J.C. Mikkelson, Jr. and J.B. Boyce, Phys. Rev. Lett. 49, 1412 (1982). 

J. Hornstra and W.J. Bartels, /. Cryst. Growth 44, 513 (1978). 

J.C. Woicik, Phys. Rev. B 57, 1 (1998). 

l?N. Keating, Phys. Rev. 145, 637 (1966).

The N -+ A Transition from Simultaneous Measurements 

The LEGS Collaboration - Beamline X5 

The Lascr Electron Gamma Source facility (LEGS) 

provides intense, polarized, monochromatic y-ray beanis 

by Compton backscattering laser light from relarivistic 

electrons circulating in the X-Ray Ring of the National 

Synchrotron Light Source at Brookhaven National 

Laboratory. Such a beam has a high degree of polarization 

(typically -90%) with very low background and the 

energies ofthe photons arc well determined by measuring 

the loss of energy of the struck electrons(+l?h). Photon 

energies up to 333 MeV can be obtained with the present 

laser shining on 2.58 GeV electrons. With a new 

frequency-quadrupIcd laser that is now being installed 

and 2.8 GeV stored electrons, photon energies up to 470 

MeV will be obtained. 

LEGS has its high degree of polarization because 

the interaction of the laser photons with relativistic 

electrons preserves the polarization of the photons. By 

orienting the linear or circular polarization of the laser to 

give the desired polarization for the y-raj., '5 measurements 

can isolate specific contributions to n~~clear reaction 

amplitudes. If the linear polarization (direction of the 

electric field vector) is in the plane of the rcaction, the 

cross section is sensitive to electric niultipole moments. 

This cross section is denoted as oil. If the linear 

polarization is perpendicular to the rcaction plane, the 

cross section is sensitive to magnetic multipolc moments. 

This cross section is symbolized by 0,. The data is usually 

presented in term of0~~10, or oil- o,, or as the asymmetry 

C = ( 0 - o,)/(o + 0,). Comparing these cross sections 

II II 

allows for the separation of effects due to static charge 

distributions from those due to spin and current 

distributions. Thus, this polarization degree of freedom 

is extreniely important in the understanding of nucleon 

and nuclear structure. 

Since 1990, experinicnts have concentrated on single 

polarization observables (polarized beams on unpolnrized 

targets) in nuclear reactions involving the A resonance. 

The A resonance is the first excitcd state of the nucleon 

with an energy of 294 MeV above the mass of the proton 

and a width of 120 MeV. It decays with a 99.4% branch 

to pion-nucleon (nN) final states and a 0.6% branch to 

yN. By st~~dying photon induced nuclear reactions in 

the energy region of this excitation, it is possihlc to 

measure fi~ndamcntul quantities such ns the deformation 

of the A, to test niodcls describing the intcrnnl structure 

ofthc nuclcon and the A and the transition hetwc.cn them, 

and to study thc effccts of A's produccd inside of nuclei. 

Highlights of this year's resr~lts arc given below. An 

updated status of I.EGS, including recent puhlicntions, 

is available on the World Wide Wcl~ at littp:// 

W'WLEGS.RNL.GOV/-I.F,

complication of independent systematic errors. In our 

current work,p($~),p(.Tifn-+) andp($ y) cross sections 

and beam asymmetries have all been measured in a single 

experiment and a dispersion calculation of Compton 

scattering has been used to provide two new constraints 

on the photo-pion multipoles. 

Both Compton scattering and no-production have 

a proton and at least one photon in their final states. We 

have made the first complete separation of these two 

processes. The two reactions were distinguished by 

comparing their y-ray and proton-recoil energies. High 

energy ?I-rays were detected in a large NaI(T1) crystal, 

while recoil protons were tracked through wire chambers 

and stopped in an array of plastic scintillators. By 

measuring more kinematic parameters than are required 

to specify the reaction, all detector efficiencies are 

determined directly from the data itself. 

Near the A peak (= 320 MeV photon energy), the 

spin-averaged no, n+, and Compton cross sections found 

here are consistently higher than earlier measurements 

from B~nn[~-~], while for energies lower than +270 MeV 

substantial agreement is obtained. We present here results 

at 323 MeV and 265 MeV as examples. Angular 

distributions for p(? ~)),p(g n-+) andp(3 y) are shown 

with their measurement uncertainties as solid circles in 

the figure. All cross sections are locked together with a 

common systematic scale uncertainty, due to possible flux 

and target thickness variations, of 2%. 

In the center panel of Figure N-1, n+ cross sections 

from Tokyo['] are shown as cross-hatched squares. These 

are in good agreement with the present work. In the 

right panel, two recent Compton measurements from 

Mainz at 90" and 75" are shown as open circle~[~~"~]. These 

data sets are in quite good agreement with the present 

work over our full energy range. As discussed in Ref. [14}, 

earlier 90" Compton cross sections from Bonn[l5] are 

about 28% too low in the vicinity of the A peak. Whatever 

the error in that early experiment, it is likely to be common 

to all angles - measured with the same detector. The Bonn 

results are shown here, rescaled by 1.28 (open squares). 

To obtain a consistent description of these results 

we have performed an energy-dependent analysis, 

expanding the n-production amplitude into electric and 

magnetic partial waves. Once the (y, TC ) multipoles are 

specified, the imaginary parts of the six Compton helicity 

amplitudes are completely determined by unitarity, and 

dispersion integrals can be used to calculate their real 

parts. 

Figure N-I : Cross sections (top row), and polarization asymmetries Z=(o -o,)/(oll+o,) (bottom row), from 

the present work (0) for p(2 n?) - left panel, p(gz?) - center, and p(lkd- right panel, together with 

published data - (y,nO): 116-181, (y,x+): [9,10,19,20], (y,$ 115 (see text),9-111. Results are shown for 265 MeV 

(323 MeV) beam energy with scales on the left (right) of each plot. Predictions from our multipole fit are 

shown with uncertainties as bands bounded by solid curves. Predictions from the VPI[SP97k] multipoles 

[21] are given by dash-dot curves. The dotted curves in the right panel show the Compton predictions 

using the prescription in refs. 112, 221.

I Quantity I This Experiment I Particle Data Group141 

I A,,, 1 -137.4 (X 10.' GeV-'I2) f 1.8 (stdttryi) *I .8 (mdd) I -141f5 

I A,,, 1 -268.9 (x 10-I GeV-'I2) 22.8 (stdtty~) f4.9 (nlodd) 1 -257f8 

I EMR 1 -3.0 (%) M.3 (rmrty) 50.2 (i~odf,!) 1 -1.5 (S,)i0.4 

Figure N-2: Table. 

Fitting the parameters of thc (y,~) multipoles by 

minimizing x2 for both prcdicted (y,n) and (y,y) 

observables allows the extraction of the EMR. In this fit 

we have usedp(? c), p(2 ~r) andp(z y) cross scctions 

only from the present experiment, since these are locked 

together with a small common scale uncertainty and 

augmented our beam asymmetry data with other 

published polarization ratios in which systematic errors 

tend to cancel. 

The predictions from the (y,~) multipoles 

determined in this fit are shown in the figurc as pairs of 

solid curves to indicate the corrcsponding uncertainty 

bands. The reduced x2 for this analysis is 

x2, = 997/(644-34) = 1.63 . 

The EMR for N+ A is -0.0296 M.0021. The 

fitting errors reflects all statistical and systematic 

uncertainties. Combining model uncertainties in 

quadrature leads to our final results given in Figure N-2 

along with the values accepted by the Particle Data group 

for comparison. 

Other information on the structure of the nucleon 

can be extracted from these data and this work is in 

progress. In particular, when placed in a strong static 

electric or magnetic field, a proton or neutron will 

experience an internal rearrangement of the quarks and 

gluons. An electric field will induce a dynamic electric 

dipole moment by separating the positive and negative 

quarks and a magnetic field will produce a dynamic 

magnetic dipole moment by separating the currents and1 

or spins of the quarks. The measure of the ease with 

which these internal rearrangements can be done is called 

the electric, magnetic, or spin polarizability. 

Determination of the polarizabilities of the neutron 

require a neutron target. Since thc free neutron is not a 

stable particle, deuterium the lightest isotope of hydrogcn 

is commonly used to provide a quasi-frcc ncutron. Here 

the single proton and ncutron arc bound by only 2.2 MeV, 

minimizing the corrcctions necessary to go from tlic 

bound neutron to the frec ncutron. 

Since the initial photon and ncutron havc no chnrgc, 

a dctcctor is required that has a good efficiency for ncutral 

particlc in the final state (x" which dccays to 2js, y-rays, 

and ncutrons) as will as charged particles. to provide thc 

neutral particlc efficiency and thc angular covcragc for 

charged and uncharged particles, a new dctcctor has bccn 

commissioned. SASY, the Spin-ASYmmctry dctcctor 

array provides coniplctc dctcrrnination of angle, energy, 

and particle identity for all rcactions induccd by photons 

on hydrogen and deuterium over thc cntirc cncrgy rangc 

planned for LEGS. SASY will consist of scvcral "layers" 

designed to fulfill these rcquircments. 

The construction of SASY is bcing donc in two 

phascs. For the first set of cxpcrimcnts to measure tlic 

electric and magnetic polariznbility of thc neutron, only 

the major calorimetry subsystcms will be instrumcntcd: 

the XTAL BOX (an army of 432 Nnl(TI) crystals) covering 

all azimuthal angles for scattcring angles between nhout 

40' and 130°, the forward ncutron wall of plastic 

scintillator consisting of thrce layers of I0 cm x 10 cm x 

1.6 m bars, and thc wall of 176 Pb-glass Ccrcnkov 

counters. The second phase will add thc capability to track 

charged particles through a largc volurnc magnctic ficld 

thereby permitting the idcntification of thc sign of tlic 

charge. This is crucial for thc thc next phase of LEGS in 

which double-polarization data will he obtained from tlic 

polarized hydrogen and deuterium using the a novel, 

polarized HD target. This is now in the dcvclopmcnt stagc 

and initial expcrimcnts (without tracking) will begin in 

the summcr of 1398. 

Measurement of Compton scattcring from thc 

ncutron occupied most of calendar 1997. Thcsc data arc 

presently being analyzed.

LEGS Collaboration, G. Blanpied et al., Phys. Rev. Lett. 69, 1880 (1 $I%). 

R. Davidson, N. Mukhopadhyay, R. Wittman, Phys. Rev. D43, 71 (1991). 

M. Khandaker and A.M. Sandorfi, Phys. Rev. D5 1, 3966 (1 995). 

Particle Data Group, L. Montanet et al., Phys. Rev. D5@, 1712 (1994). 

I. S. Barker, A. Donnachie and J.K. Storrow, Nucl. Phys. B95, 347 (1975). 

H. Genzel etal., 2. PhysikA268, 43 (1974). 

G. Fischer et al., Z. Physik 253, 38 (1972). 

K. Biichler, et dl., Nucl. Phys. A570, 580 ( 1 994). 

T. Fujii etal., Nucl. Phys. B120, 395 (1977). 

.V.A. Get'man etal., Nucl. Phys. B188, 397 (1981). 

C. Molinari et al., Phys. Lett. B37 1, 18 1 ( 1996); 

J. Peise etal., Phys. Lett. B384, 37 (1996); J. Ahrens, Priv. Comm. 

G. ~arbiellini et al., Phys. Rev. 174, 1665 (1968). 

LEGS Collaboration, G. Blanpied et al., Phys. Rev. Lett. 76, 1023 (1996). 

H. Genzel et al., Z. Physik A279, 399 ( 1 976). 

R. Beck etal., Phys. Rev. Lett. 78, 606, 1997; H.-I? Krahn, thesis, U. Mainz (1996). 

H. Genzel et al., Z. Physik A268,43 (1 974). 

A. Belyaev et al., Nucl. PI$. B213, 20 1 (1 983). 

C. Fischer et nl., Z. PIysik 253, 38 (1 972). 

K. Riichler, et a!., Nucl. Pllys. A570, 580 (1994). 

,SAID code (1 996), telner WINTE.PHYS.W.EDU {physics,quantum}; 

It. Arndt, I. Strakovsky and R. Workman, I'hys. f

Beamline X3B1: The previously unknown compound Rb,Pb,CI, (shown at right, with c axis 

pointing vertically) was synthesized by melting a stoichiomentric mixture of RbCl and PbCI, at 

700% and annealing for several weeks at 200°C. Although the metrics could be determined 

from laboratory powder diffraction patterns, the structure could only be solved by using 

synchrotron radiation. This new type of structure shows a large variety of different 

coordination polyhedra for the cations: columns of tetragonal prism and antiprism are mixed 

with caped trigonal prism and a 6+2+2 polyhedron of a new type. (See also Abstract on page 

B-47). H.P Beck, M. Schramm, R. Haberkorn (U. of Saarland), R.E. Dinnebier (U. of Bayreuth), 

and P.W. Stephens (SUNY @ Stony Brook).

THE 1997 NSLS ANNUAL USERS' MEETING 

Joel D. Brock 

Cornell University 

NSLS Users' Executive Committee Chairman 

The users of the National Synchrotron Light Source 

(NSLS) held their annual Users' Meeting on May 20, 

1997, ;It Brookhaven National Laboratory (BNL). This 

meeting serves several functions: celebrating the scientific 

3rd technical accomplishments of the previous year, 

obtaining the latest news on the U.S. Department of 

EnerLpSy's support for scientific facilities in ~cneral and the 

NSIS in particular, and providing an opportunity to visit 

\virh old friends and collcngues. ,\s in past ?curs, six 

workshops on scientific and technical topics (descriptions 

t.ollow this article) were held the day hchrc and the day 

;iItcr rhc main mccting. 

.l'lic meeting began with ;I lively and humorous key- 

note ;&tress titled "Future Schlock" hy liobcrt Ihk, 

I'rofcssor of Physics at the University of M;~ryland and 

author of the WWW newslopinion page "What's Ncw". 

.innual funding increases. He then continued with several 

cxamples of predictions made by various fururists and 

concluded with the point that no one predicted that 

scientists would become politically active or how powerful 

their voice would be. 

The Interim Director of BNL and President ofAUI. 

Lyle Schwartz, was the next to address the meeting. He 

hcpn his remarks by addressing recent statements in the 

press by DOE Assistant Secretary T ~ra O'Toole (see, for 

example, Science News, Vol. 1 5 1, p. 284, May 10, 1997) 

that the highly publicized deficiencies in Environment, 

Safety nnd Health at BNL were the fault of users. Dr. 

Schwartz strongly defended the users. He then solicired 

rhcir comments and observations during this time of 

change at DNL. 

The U.S. Department of Energy was represented 

The main point of Park's address was that one c~nt~ot I y the Associate Director of Energy Research for the 

make accurate predictions about the filture. He began Office of Basic Energ Sciences. Patricia M. Dehmer. In 

I>!. pointing out that one ycar up, no one was predicting light of the two previous speakers' remarks. she began 

that today we would huvc hudgcts before (:ongrcss which her remarks by assuring the rudience that during all the 

horh balance the budget by the ycar LOO2 and give science upheaval associated with BNCs problcms there has been 

one constant: "the high rcgard" for the NSLS, its 

users, and the quality of their science. She then 

went on to outline the organizarional structure 

of the DOE, pointing out that the Basic Energy 

Sciences (BES) I~tdgct is roughly equal to that 

ofthe National Science Foundation. but that BES 

hnds thrcc times the amount of physical science 

rcscarch a~nd most of the major user facilities in 

the country. She urged the audience to 

Robert L. Park (left) of the University of Maryland after his Keynote 

Speech "Future Schlock" talking with Denis McWhan (center), 

Associate BNL Director, Basic Energy Science Programs and Lyle 

communicate with BES (BES@~er.doe.~ov) 

answering the question, "How has your discipline 

been affected by synchrotron radiation and how 

would it be affected b!, the lack of it?" 

Next, Larry Dubois, director of DARPAI 

DSO, gave an overview of materials research from 

a DARPA perspective. Emphasizing the potential 

applications, he cited iii situ studies of fuel cells, 

studies of "relaxor" piezo-electric materials, and 

Schwartz, Interim BNL Director and President of Associated x-ray patterning of materials as examples of areas 

Universities, Incorporated. 

where synchrotron x-my techniques might be of

interest to DARPA. 

The last speaker of the morning was Michael 

Hart, Chairman of the NSLS. His remarks were 

focused primarily on the BESAC review panel on 

synchrotron radiation facilities which would be visiting 

NSLS on June 25 and 26. Part of the review will be 

presentations by NSLS users. He requested the 

continued assistance of the user community during 

this review process. 

In dramatic contrast to the morning session, the 

afternoon was devoted to scientific talks spanning the 

wavelength spectrum from the far infra-red through 

the ultra violet into the hard x-ray region. Albert J. 

Sievers led off, discussing the coherent generation of 

FIR and describing experiments he has performed 

using the LINAC at Cornell. In these experiments, 

he used FIR as a diagnostic probe to measure the profile 

of the electron bunch. As part of his presentation, he 

walked the audience through a very clear explanation 

of how one uses Kramers-Kronig relations to solve the 

phase problem in time/frequency Fourier transforms. 

Robert Bartpski spoke next on his coincidence 

spectroscopy measurements of TiO,. The basic idea of 

the technique is to trigger off of a core level photo-electron 

and then require the coincidence of a particular Auger 

electron associated with the death of the core hole. 

Requiring the coincidence gives the technique both 

elemental and valence sensitivity and the low background 

enables one to determine defect densities on the order of 

2%. Data illustrating the effects of different surface 

preparations on the densities of point defects with 

particular Ti valence states were presented. 

From left to right: Susan Barr, APS User Program 

Administrator; Constance Pittroff, APS Assistant User 

Program Administrator; Eva Z. Rothman, NSLS User 

Administrator; and Elizabeth Saucier, ALS User 

Administrator. 

Keith Bowen (left) of the University of Warwick, UK and 

Bede Scientific Instruments conversing at the User 

Meeting Poster Session with Michael Hart, Chairman of 

the NSLS. 

Thomas Gog discussed his recent work on Multi- 

Energy X-ray Holography, presenting reconstructed 

images of several different systems. Although the 

technique is still at an early stage of development, the 

potential to produce atomic resolution real-space images 

was tantalizing. He discussed several current technical 

challenges yet to be overcome, including developing a 

better understanding of the effects ofwavelength filtering 

on the numerical Fourier transform. 

The last speaker of the afternoon, Donald Weidner 

described his work using x-ray diffraction at high pressures 

and temperatures to study the phase diagram of materials 

found in the Earth's crust, He related that work to a 

self-consistent mathematical model which explains 

an anomaly in the frequency distribution of deep 

earthquakes. 

Two other important features of the Users' 

Meeting were the scientific poster session, with a 

reception at the Brookhaven Center, and the 

equipment exhibit in the Lobby of Berkner Hall. 

Both were popular with the users, providing an 

opportunity to get a preview of some of the latest 

work performed at the NSLS and to see some of the 

new equipment available from suppliers. 

The election of the NSLS UEC occurred during 

lunch. Paul Stevens, Barbara Illman and John Parise 

were elected as general members. The SPIG 

representatives will be elected by e-mail ballot after 

the meeting. On Wednesday, in executive session, 

the UEC chose John Parise to be its Vice-Chair 

(Chair-Elect). W

The Im act of New Detector 

~echnoro~ on Synchrotron 

Macromo ecular Crystallography 

Malcolm Capel 

(Brookhaven National Laboratory, Biology) 

The goals of the workshop, held on May 19, 1997, 

was to summarize recent developments in imaging x-ray 

detector technology (predominantly CCD's) and to 

discuss issues related to their capabilities and performance 

in regard to macromolecular crystallography as practiced 

at x-ray synchrotrons. Leaders in the fields of CCD 

detector, crystallography software and x-ray heamline 

development gave presentations to an audience of 

approximately 45 registered attendees. 

Ed Westbrook, director of the Structural Biology 

Center (SBC) at Argonnc National Laboratory discussed 

the status of the Advanced Photon Source Sector 19 SRC 

beamline and its 3x3 CCD array detector, developed 

jointly by the SBC and Steve Naday ofAN1,'s Electronics 

and CommunicationsTechnology division. This detector 

(known as the APS-I) is constructed from 9 CCD-optical 

fiber taper cells, and has an active area 20x20 cm in size, 

with 3000 x 3000 pixels, reads out in 3.3 seconds and is 

capable of resolving approximately 280 diffraction orders 

from protein crystals. The SBC beamline presently is 

capable of producing a beam with a flux of 3 x loT5 

monochromatic photons/second/mm2 (0.01 O/o 

bandpass). Complete, fine phi-sliced rotation data sets 

can be acquired from lysozyme in about 20 minutes with 

merging statistics around the 2-3% level. 

Bob Sweet (NSLS X12C, BNL Biology) provided 

a synopsis of the design and working principals of the 

mosaic CCD crystallography detector design and a 

historical summary of various CCD dctcctors trialed at 

the NSLS X12C crystallography beamline. M;lrty 

Stanton (Brandeis University) dcscribcd his gro~lp's CCI) 

detector development with special emphasis on a 

programmable CCD controllcr/sequc~~cer designed hy his 

group for dynamical diffraction studies with musclc. Fxic 

Eikenherry (Princeton University) discussed design and 

testing of a prototype solid-state pixcl-nrray detector, the 

likely successor technoloF to CCD's in cryst;lllograf7hy 

and synchrotron-based diffraction studies. 

The afternoon session of the worl

Biological and Chemical 

Applications of EXAFS 

Spectroscopy 

Dr. Mark R. Chance 

(Albert Einstein College of Medicine) 

A workshop entitled "Biological and Chemical 

Applications of EXAFS Spectroscopy" was held at the 

National Synchrotron Light Source on May 21, 1997. 

EXAFS is one of the most widely used techniques at the 

NSLS and the presentations highlighted recent research 

from four of the major groups performing EXAFS at the 

facility. The first presentation however, was from Dr. Frank 

de Groot of the University of Gronigen entitled "Multiplet 

Effects in Core Level Spectroscopies". The interesting 

initial question answered by Dr. de Groot concerned the 

necessity of multiplet analysis. It is well known that single 

scattering can work well in describing spectral data. In 

the case of L-edge spectroscopy, the 2p-3d interactions 

are very strong and the single particle approximation 

breaks down. Dr. de Groot provided a description and 

an analysis of results using atomic multiplet theory, where 

electron-electron interactions determine the multiplets 

and spin-orbit couplings determine the fine structure. 

Introduction of crystal field splittings provided satisfactory 

molecular simulations providing values of ligand field 

strength, high or low spin and valency. Further 

information on the programs is available at http:// 

vsfl .phys.rug.nl/-degroot. 

Professor Dale Sayers from North Carolina State 

University, gave a talk entitled "XAS Determination of 

Chemical Speciation of Heavy Metals". Dr. Sayers' 

presentation highlighted the magnitude of the 

environmental problem presented by heavy metals and 

the keen ability of XAS to probe the structure of these 

metals in soil samples. The first example determined the 

efficacy of hydroxyapatite treatment in the remediation 

of lead in soil samples, which can successfully sequester 

the lead as an insoluble form. A second analysis of lead 

waste from batteries determined the degree of conversion 

of lead oxide to lead sulfide forms (the latter being 

relatively insoluble). XAS was very powerful in 

determining the metal environment. Dr. Sayers also briefly 

spoke about the International XAS Society, more 

information can be found at http://ixs.iit.edu 

Professor James Penner-Hahn of the University of 

Michigan gave a talk entitled "Structural Characterization 

of Organometallic Reagents", providing interesting results 

refuting the presumed existence of higher order cuprates 

and providing a better understanding of phenyl copper 

complexes with very precise titration data. 

Professor Mark Chance from the Albert Einstein 

College of Medicine illustrated a number of applications 

of FEFF to analyzing structure in biological systems. A 

program called AUTOFIT 1.0 was outlined that can 

automatically iterate crystal structure data, simulate the 

resultant FEFF spectra, and compare the simulations to 

experimental data in order to map different possible 

solutions in an evenhanded fashion. Further information 

on the programs can be found at http:// 

beam.aecom.yu.edu/phys&bio/csb 1 .htm 

Ms. Lijun Shu from the University of Minnesota 

finished the talks with a discussion of "Diamond Core" 

structures (Fe,O,) in enzymes like methane monoxygenase 

and ribonucleotide reductase. The Fe-Fe distances for 

some of the high valent intermediates were as short as 

2.4 A. Lastly, Dr. Lars Furenlid of the NSLS provided a 

demonstration of the 100 element solid state detector 

that was set up at beamline X9B on the NSLS floor. As 

the workshop attendees clustered about the beamline we 

were immensely impressed with the miniaturization of 

the detector elements (30-40 times smaller than 

conventional solid state detector elements). W

X-ray Computed 

Microtomogra hy : 

Applications 8 q echniques 

Betsy Dowd 

(Brookhaven National Laboratory, NSLS) 

The availability of synchrotron X-ray sources to the 

scientific community sparked the first explosion in the 

development of the field of X-ray Computed 

Microtomography (XCMT). More recently, 

technological advances in two-dimensional detector 

arrays, combined with the recent boom in available 

parallel architecture computing technology, have lifted 

the XCMT field to another level. Talks at this workshop 

highlighted the impact of these technological advances 

on a variety of applications of XCMT, from the medical 

to the metallurgical fields. 

A detailed synopsis of the rapid progression of 

Exxon's X-ray CMT facility at the NSLS over the past 15 

years, in parallel with improved detector, processor, and 

3-D visualization technology, was given by John 

Dunsmuir (Exxon Corp.). John and his team now 

routinely use XCMT to characterize reservoir sandstone 

pore geometries. 

Per Spanne (ESRF) discussed XCMT applications 

and advances at the ESRF. By parallelizing 1 G computers, 

the group at ESRF has significantly reduced the 

reconstruction time for tomographic volumes. Per and 

his colleagues at the ESRF have also used the high 

coherence of the ESRF X-ray source to make phase 

contrast CMT measurements. 

Chris Jacobsen (SUNY, Stony Brook) presented 

schemes for soft X-ray submicron resolution tornograph): 

Zhong Zhong (NSLS) and Avraham Dilnianian (BNI., 

Medical Dcpt.) proposed a plan for Diffraction Enhanced 

Computed Tomography for biological tissue 

characterization. 

The present status and recent applications of the 

XCMT f;~cility developed by the NS1.S were reported by 

Betsy Do\vd (NS1.S). The versntility of this developing 

user facility was cmphasi7.cd by the variety of tomographic 

volumes generated. Among these arc reservoir sandsto~ics 

(h4ohil Corp.), basalts (Sahnzian, Univ. of N.M., Song, 

National Taiwan Univ.), porous nictals (Schultc, 

Northrop-Grurnn~an Corp.), and plasma-spray coatings 

( Herman, SUNY, Stony Brook). Barhara Illmuti (USDAI 

FS Forest Products Lab., U. of Wisconsin) has ohtained 

CMT volumes of bcctlcs and wood at this facility and 

spoke about her application of CMT to the study of 

funzal deterioration ofwood. Shcng-Rong Song (Geology 

Dept., National Taiwan U.) spoke about his investigatio~is 

into volcanic rock, using CMT data he collcctcd at the 

NSLS facility 

Brent Lindquist (SUNY, Stony Brook) gave an 

entertaining and informative tutorial on his 3-D Mcdinl 

Axis (3DMA) program he developed to cliar;~ctcrizc the 

pore geometries from tomographic data of rocks. For the 

final talk by Ballard Andrcws (RNI.-COI~~I~~I & 

Communications Division) , our group moved to the 

3D visuali7.ation theater at BNL, where each participant 

donned a pair of glasses, and relaxed to enjoy a 

stereo denlonstration ofsome tomographic data collcctcd 

at the NSLS. In addition to demonstrating 

. 

this impressive 

facility, Ballard enlightened us with his knowledge of 3- 

D visualization and rendering techniques, and 

applications of IBM Data Explorer to viewing and 

analyzing tomographic data.

Inelastic and Resonant Inelastic 

X-Ray Scattering 

Chi-Chang Kao 

(Brookhaven National Laboratory, NSLS) 

Inelastic x-ray scattering has long been recognized 

as a potentially important experimental probe of electron 

and lattice dynamics in condensed matter systems. 

Recently, several dedicated high resolution (total energy 

resolution from 0.1 eV to 1.0 eV) and ultra-high 

resolution (total energy resolution from 1 meV to 10 

meV) inelastic scattering beamlines have become 

operational around the world. The latest experimental 

results from these beamlines as well as various theoretical 

aspects of inelastic x-ray scattering were reported at the 

workshop. 

Denis McWhan (BNL) opened the workshop by 

giving a brief review of the major steps in the development 

of inelastic x-ray scattering. The relationship between 

inelastic x-ray scattering and inelastic scattering of visible 

light was discussed by Miles Klein (University of Illinois- 

Urbana/Champaign). Although he found little analogy 

between the two techniques, he did suggest several areas 

in which inelastic x-ray scattering might provide new 

information. He also reported recent visible light 

scattering studies on high temperature superconductors 

and related compounds. 

Inelastic x-ray scattering studies of many-body 

correlation effects in simple metals were reported by Ben 

Larson (Oak Ridge National Lab.) and John Hill (BNL- 

Physics). Ben Larson found that the measured local-field 

factors of A1 are significantly larger those that obtained 

from a first principle theoretical calculation. To resolve a 

long standing controversy over the origin of the double- 

peak feature in the inelastic scattering spectra of many 

materials, John Hill reported an inelastic x-ray scattering 

study of solid and liquid Li and Na, in which spectral 

features from band structure effects are separated from 

those due tomany-body effects. 

There were also several talks on resonant Raman 

scattering, or resonant inelastic scattering, studies on 

highly correlated systems. John Hill along with Eric Isaacs 

(Bell Laboratories) reported recent Cu K-edge resonant 

inelastic study of Nd2Cu0, and Sr,Cu02C12, respectively. 

Trever Tyson (New Jersey Institute of Technology) 

presented high resolution Mn K-beta emission spectra of 

a series of doped LaMnO, compounds. On the theory 

side, Frank de Groot (University of Groningen, The 

Netherlands) presented an atomic-multiplet based model 

calculation for resonant Raman scattering. Very good 

agreement between theory and experimental results, 

ranging from soft-x-ray to hard-x-ray, were shown. 

In addition to the works done at the NSLS, 

Francesco Sette of the European Synchrotron Radiation 

Facility (ESRF) reported an ultra-high resolution inelastic 

x-ray scattering study of the high frequency collective 

dynamics of disordered systems, a region in the energy- 

momentum phase space that cannot be accessed by 

inelastic neutron scattering. The status of the inelastic 

scattering beamline at the Advanced Photon Source 

(APS), and first results were reported by Albert 

Macrander..

Materials Characterization with 

Hard and Soft X-ray Reflectivity 

Michael Toney 

(IBM Almaden Research Center) 

Yves ldzerda (Naval Research Lab) 

Specular and diffuse X-ray reflectivity are popular 

methods for characterizing a variety of materials, including 

organic thin films, magnetic filnis and surfaces, and 

semiconducting materials. This motivated a one day 

workshop held May 19, 1997 in conjunction with the 

NSLS Users' meeting. The purposes were to gather 

together novices and experts to discuss these methods and 

their applications, to educate newcomers on the power 

of these methods, and for the NSLS reflectivity 

community to discuss building an endstation dedicated 

to reflectivity 

Professor Carol Thompson (ANL and Northern 

Illinois University) kicked off the workshop with an 

introduction to X-ray reflectivity, including a description 

of questions that could (and could not) be addressed and 

of important experimental requirements, such as 

spectrometer and sample alignment. She also emphasized 

that hard x-rays can be used under ambient conditions 

(e.g., in an electrolyte). Examples wcrc given of layering 

of smectic liquid crystals on glass and of in sitlr swelling 

of PMDA-ODA in NaOH. 

Paul Mansky (U. of Massachusetts) compared and 

contrasted x-ray rcflcctivity with neutron reflecti~' 71t j 7 as 

applied to organic thin films. The advantages of isotopic 

substitution (D for H) wcrc denlonstrated, and the 

complementarity of using both x-ray and neutron 

reflectivity was illustrated. Data for polymer brushes 

(polymers bound to a surface at one end) showed how 

the polymers swelled with increasing teniperaturc, 

consistent with theory. Paul also described studies of 

islands in di-block copolymer system$. 

This was followed by Eric Chason's (Sandia National 

Lab.) talk on in sitzr reflectivity studies of the evolution 

of thin film and surhce morphology Eric described an 

energy dispersive technique for time resolved 

measurements (ca. 25Osec data collection time). He 

illustrated several examples, including compound 

formation during Al deposition on CrIquartz, the 

formation of pits in porous silicon, the CVD growth of 

Fe on Si(1 00), and the surface roughening (smoothing) 

of quartz during ion bombardment with Xe (He). There 

was discussion of the possible advantages of synchrotron 

radiation for such studies and of the need for detectors 

with higher throughput. 

After a break for an enjoyable lunch and a change 

in energy range, Jack Rife (Naval Rescnrch Lah.) talked 

about UV and soft x-ray reflectance characterization of 

semiconductor materials. He explained the technique and 

described the X24C reflectance setup. He then reviewed 

the application of this method to GaN and compared 

the experiments to theory with favorable agrcemcnt. This 

was followed by studies of radiation damage in SiO, 

through bombardment with 5cV neutral oxygen atoms 

(motivated by etching of surfaces of the space shuttle in 

low earth orbit). 

Gavin Watson returned to the hard x-ray regime 

with a discussion of x-ray resonant magnetic reflectivity. 

After describing the technique and emphasizing that it is 

a resonant method, Gavin described the near-surfacc, 

antiferroniagnetic ordering in UO,(OO 1 ) and how this 

differs from bulk ordering. Gavin also showcd how this 

method could be used to understand the magnetism on 

Pt in Co,Pt, and in a brief excursion to lower energies, 

sho\ved how the magnetic roughness in ColCu ni~~ltil;lyers 

\vas less than the atomic roughness.

The emphasis on third row transition metals was 

continued by John Freeland (NSLS, U4B) whose talk 

was entitled "Materials Characterization with Resonant 

Soft X-rail Scattering". John explained how this method 

was rclared to x-ray circular dichorism and resonant x- 

rav scattering and how it could be used to obtain magnetic 

md atomic thickness and roughness. He showed the huge 

enhancements in cross scctions that could be obrained 

for third row transition elements and described studies 

of switching in NiFeICo sandwiches. This was followed 

by determinations of magnetic and chemical roughness 

in single Co films and CoFe multilayers. 

Near the end ofthe workshop, there was discussion 

of a possible endstation dedicated to reflectivity. In this 

arrangement, the NSLS would provide x-rays up to the 

hutch and the interested users would fund construction 

of the endstation. Jerry Hastings (NSLS) explained what 

had been done by the polymer SAXS community on 

X27C, and sevsral speakers (Thompson, Watson, Evans- 

Lutterodt) described what they would like for such a 

reflectivity endstation. This would cost the interested users 

approximately $200,000 or more, and with enough 

support, could be constructed. After much discussion, it 

scems [here is insufficient funding in the user community 

present at the workshop (either academic or industrial) 

for the construction of such a beamlinelendstation, 

although some NSLS staff members are actively interested 

in collaborating on reflectivity experiments and 

instrumentation.

Beamline U9B: The Fluorescence Omnilyzer is a single-photon detector developed to record 

all of the ihportant parameters of a fluorescence emission spectrum simultaneously. The 

figure shows the time-wavelength histogram for pyrene in ethanol. The horizontal axis is time 

after excitation, in nanoseconds, and the vertical axis is the wavelength of the fluorescent 

light. The intensity (number of photons) recorded for each time-wavelength cell is represented 

in pseudo-color as a rainbow transformation. Determining all of the important parameters 

that characterize a fluorescence emission spectrum simultaneously with the Omnilyzer is 

particularly important in studies of fragile biological and chemical samples that can be 

damaged by prolonged exposure to the fluorescence excitation beam. (See also Abstract on 

page A-49.) 

In 1997, the Omnilyzer was selected by R8D Magazine as one of the 100 most significant 

technological developments of the year. A more detailed description of the Omnilyzer is 

available at http://www.biology.bnl.gov/biodocs/nsls/u9b/omnilyzer.htmlx 

Lisa A. Kelly (NSLWBNL-Biology. Present Address: U. of Maryland, Baltimore County), John C. 

Trunk, and John C. Sutherland (BNL - Biology).

Figure 1 shows the breakdown of the VUV Ring 

operating statistics for the Fiscal Year 1997. The monthly 

breakdown of most significant operational performance 

statistics are presented in Figures 2 through 6. The 

operational statistics continue to show improvement 

above the record year of FY 1996. The fraction of the 

time during the year resulting in unscheduled downtime 

was only 1.5%. The probability that beam was not 

available when it was scheduled for operations was only 

2.38%. However the total beam time actually delivered 

to the users was 6 hours greater than was scheduled, or 

100.1 O/o of scheduled. This resulted from the early return 

from maintenance and a reduction in accelerator study 

hours actually used. The accelerator performaqce 

continued to improve with higher injection rates and 

longer beam lifetimes. Injections are now routinely done 

in less than 3 minutes with the average approaching 2 

minutes. The beam lifetime had been lower due to higher - 

vacuum resulting from the two openings of the ring 

during the year and due to vacuum leaks. However, from 

August through the end of the year the lifetime has 

exceeded the pre-shutdown values by about 8%. This 

was achieved despite the new gas load introduced by the 

new UI2IR mirror being inserted into the ring vacuum 

chamber and a leak in the front-ends of two beam ports. 

To help reduce the impact of these new gas loads. a new 

beam scrubbing shift (vacuum chamber conditioning 

shift) was introduced during - the owl shift (0:OO to 08:00) 

of the tivo day study pcriod that occurs once a month. 

This shift helps desorb the gas that was introduced by 

these new sources more rapidly than would occur during 

normal operations and helps reduce the base pressure of 

the ring. 

The major improvement to the VUV Ring during 

this fiscal vear occurred during - the winter shutdown when 

another large aperture beam port was installed for the 

U2IR beamline. The ceramic gap just after this beam 

chamber had started to leak during the fall 1996 and was 

also replaced during the winter shutdown of the ring. 

Despite the increased work load from the ceramic gap 

replacement, the effective planning of the Mechanical 

Group allowed the ring to be brought on four days early 

VUV MACHINE 


VUV Ring Manager 

and scrubbing of the vacuum with beam to take place 

during the three day holiday weekend. This allowed 

operations to begin on schedule but with longer beam 

lifetime resulting from the reduced vacuum pressure. 

During the spring, a front-end valve started leaking in 

the half of the ring opened during the winter shutdown. 

This valve was replaced during the May shutdown 

requiring the same half of the vacuum chamber to be 

vented again. Recovery to pe-shutdown values of the 

beam lifetime required about the same integrated - current 

as the winter shutdown, but since this vacuum work had 

not been anticipated, much of the beam scrubbing had 

to be done during operations. 

Other improvements in the ring resulted from 

changes in the damping of higher order mode of the main 

RF cavity and other changes in this RF control system. 

Testing began on the implementation of a fast RF 

feedback system on the main RF system. This system 

should suppress the noise introduced by that RF system 

- - 

on the beam and it appeared to work quite well when 

operated by itself. However, when the bunch lengthening 

RF system was also working the beam showed increased 

fluctuations and will require more work to allow these 

rwo systems ro work together. Other improvements were 

in the diagnostics of the electron and photon beams. New 

extended dynamic range Beam Position Monitor (BPM) 

receivers were installed on all of the ring's pickups. This 

will allow measurements of the beam position down to 

lower vrilucs of currcnt. This of little concern for normal 

operating currents but will help better understand the 

electron beam model for the ring by allowing 

measurements at low beam current. A new fast turn-to- 

turn BPM measurement system was prototyped and the 

full system should be operational in FY 1998. This BPM 

will allow modeling of the non-linear properties of the 

electron beam. Other diagnostic improvements that are 

- 

planned will help understand the fast beam fluctuations 

and how to reduce their impact on the users. 

The long awaited improvement in the VUV 

radiation shielding did not take place during FY 1997, as 

it was originally planned. This was due to the difficulty 

in finding suppliers of the heavy concrete shielding blocks.

However, this supply difficulty has been overcome and 

the shielding is planned to be installed around half of the 

ring during the winter 1997-1998 shutdown. Once the 

improvement in the radiation levels in that half of the 

ring is measured the remainder of the shielding will be 

scheduled for a future shutdown. When the radiation 

shielding has been installed new studies of the Top-Off 

Method of Injection (TOMI) will be performed, in order 

to demonstrate that TOM1 offers the users the ultimate 

improvement in beam stability over long time periods 

both from the source and the optics points ofview. TOM1 

will also eliminate the age old conflict between longer 

beam lifetime and higher brightness of the photon beam. 

To insure that the frequent injection pulses are not seen 

by the users, new shorter pulse kickers will be installed in 

FY 1998 to allow the injected beam to be added to the 

Figure 1 : The breakdown of 

the VUV Ring usage based on 

total time (not scheduled 

time) for FY 1997. 

Ave. fill Current: 848 mA 

Ave. Charge Rate: 168 mA/min 

Ave. Lifetime at 500 mA: 314 min 

Total user integrated current: 

2980 A-Hrs (124 A-days) 

Total hours of operation: 5752 hours 

Average operating current: 518 mA 

stored beam with minimum disturbance to the stored 

beam. 

During - the next fiscal year studies will be carried 

out to increase the operating beam energy of the W 

Ring. - This will continue the improvement in beam 

lifetime that has dominated the past improvements. In 

addition, studies are being carriedbut to develop methods 

of providing for real-time variation of the undulator gaps 

in the ring. Although this is common place on the high 

energy rings, the lower energy of the W Ring makes 

the impact of these gap changes more significant for the 

other users. The initial studies to control the orbit and 

betatron tunes roved insufficient and addition correction 

of horizontal-vertical coupling effects also will have to be 

compensated. H 

VUV Ring Time Usage 

Unsch. Ops. (1.91 00) 

Unsch. Downtime (1.58%) 

lniection (1.300/0)i 11 

Ops. (64.36O/o)

11 VUV Ring 11 

I Performance I 

Oct Dec Feb Apr Jun Aug 

Figure 3: The total integrated current for 

the VUV Ring accumulated each month. 


Figure 4: The VUV Ring vacuum pressure at 

500 mA beam cunent averaged over each 

month. 


Figure 2: The VUV Ring injection charge 

rate average over all fills in each month. 

Oct Dec Feb Apr lun Aug 

Figure 4: The injection current averaged over 

all fills in a month for the VUV Ring. 


Figure 6: The VUV Ring exponential beam 

lifetime at 500 mA beam current (seven 

bunch operation only) averaged over each 

month.

VUV STORAGE RING PARAMETERS AS OF NOVEMBER 1997 

Normal Operating Energy 

Peak Operating Current (multibunch ops.) 

Circumference 

Number of Beam Ports on Dipoles 

Number of lnsertion Devices 

Maximum Length of lnsertion Devices 

B(p) 

Electron Orbital Period 

Damping Times 

Lifetime @ 200 mA with 52 MHz 

(with 21 1 MHz Bunch Lengthening) 

Lattice Structure (Chasman-Green) 

Number of Superperiods 

Magnet Complement 

Nominal Tunes (vx,vJ 

Momentum Compaction 

RF Frequency 

Radiated Power 

RF Peak Voltage with 52 MHz (with 211 MHz) 

Iesign RF Power with 52 MHz (with 211 MHz) 

Synchrotron Tune (vS) 

Natural Energy Spread (o,/E) 

Bunch Length (20) 

(21 rm5 with 21 1 MHz Bunch Lengthening) 

Number of RF Buckets 

Typical Bunch Mode 

Horizontal Damped Emittance (E.) 

Vertical Damped Emittance (EJ 

Power per Horizontal Milliradian (1 A) 

Arc Source Parameters 

Betatron Function (Px,PS 1.18 to 2.25 m, 10.26 to 14.21 m 

0.808 GeV 

1.0 amp (1.06 x 1012e-) 

51.0 meters 

17 

2 

- 2.25 meters 

19.9 A (622 eV) 

1.41 Tesla (1.91 meters) 

170.2 nanoseconds 

.tx'ty= 13 msec; .tE = 7 msec 

360 min 

(590 min) 

Separated Function, Quad, Doublets 

4 

{ 8 Bending (1.5 meters each) 

24 Quadrupole (0.3 meters each) 

12 Sextupole (0.2 meters each) 

3.14, 1.26 

0.0235 

52.886 MHz 

20.4 kW/amp of Beam 

80 kV (20kV) 

50 kW (10 kW) 

0.0018 

5.0 x I,< 20 mA 

9.7 cm (I, < 20 mA) 

(36 cm) 

9 

7 

1.62 x lo-', meter-radian 

O 3.5 x 10-lo meter-radian (2.8 x loM9 in normal ops.)" 

3.2 Watts 

Dispersion Function (qx,qJ 0.500 to 0.062 m, 0.743 to 0.093 m 

ax,y = -0' x, J2 

yxSy =(I +ax,Y)@x,y 

Source Size (ox, oJ 

-0.046 to 1.087, 3.18 to -0.96 

0.738 to 0.970 m-l, 1.083 to 0.135 m-I 

536 to 568 ym, >60 to >70 ym (170-200 pm in normal ops.)* 

Source Divergence (ox,oJ 686 to 373 yrad, 19.5 to 6.9 prad (55-20 prad in normal ops.) 

1 

lnsertion Device Parameters 

I- 

Betatron Function (P,, PJ 11.1 m, 5.84 m 

Source Size (ox, o,) 1240 pm, >45 ym (130 pm in normal ops.)* 

I Source Divergence (ox, 0;) 112 prad, >7.7 prad (22 prad in normal ops.)* I * cy is adjustable 

4- 5

Roger Klaffky 

X-Ray Ring Manager 

In preparation for the December 1996 shutdown, 

water lines wcrc installed in Fall 1996 to bring BNL 

Central Chilled Water Facility (CCWF) water to the 

NSLS experimental water system in Mechanical 

Equipment Room A. Thc control valvc/controllcr 

installation for this system began. This upgrade was 

designed to improve temperature regulation, with the 

present NSLS experimental water system providing 

redundancy in case the CCWF goes down for 

maintenance. Thc BNL CCWF connection to the NSLS 

experimental water system was completed during thc 

December 1996 shutdown, and temperature control of 

this system was upgraded. To maintain a redundant NSLS 

cooling capability in case the CCWF goes down, the old 

Baltimore cooling tower was replaced and plans were made 

to upgrade and expand its controls. Thc experimental 

water pump capacity was increased and spigots were 

installed for bcamlincs rcqiiiring enhanced cooling. 

A major effort during the December 1996 shutdown 

X-Ray Ring Time Usage 

ComlCon (5.23%) 

Ops. (56 999'0) 

The breakdown of the X-Ray Ring usage based 

on total time (not scheduled time) for FY 1997. 

was the installation of 20 new beryllium windows to 

enable 350 n1A operation in January 1997. New windows 

were installed on X3A, X4A, X6A, XI 2A, XI 2R, X12C, 

X13, X14A, X14R, X15A, X19C, X20A, X20C, X21, 

X22A, X23A, X23B, X25, X26A and X26C. Brazing 

and welding of the windows was done by Rri~sh Wcllman 

Electrofusion with the pieces being fabricated by BNI. 

Central Shops. An additional 20 windows were also 

received, which included the remaining windows rcquircd 

for 438 mA operation and at least onc sparc window for 

each assembly type. Since the new windows had 5 mm 

vertical openings (as opposed to I0 rnm for the old 

windows), conlmissioning shifts were provided in January 

1997 to the above beamlines to confirm that thc windows 

were properly surveyed into position. 

The dual hybrid RF power amplifier was installcd 

on RF System 2 in December 1996. Two 120 kW 

amplifiers arc combined in this systeni to enable 438 niA 

operation and to prevent a beam dump ifone ofthc othcr 

I Oct Dec Fcb Apr Jun Aug I 

The total integrated current for the X-Ray Ring 

accumulated each month for FY 1997.

three RF systems drops out. After an initial 

commissioning period in January, the new dual 

transmitter on the RF2 cavity became operational. At 

present each of the transmitters is operating at half power 

(40-50 kW) with increased reliability. During the Spring 

1998 shutdown, a new all-copper cavity will replace the 

existing copper-clad steel cavity and a new copper 

coupling loop brazed to a beryllia ceramic window will 

allow the transmission of more than 150 kW into the 

cavity. This additional power will enable reliable 438 

rnA operation at 2.584 GeV or 250 mA operation at 2.8 

GeV. Improved windows for the other RF systems were 

ordered. The new cavity has several desirable features. 

There are no welded ports or joints, cooling channels are 

machined in the outside skin, and there is an improved 

mushroom cooling. The cavity was shipped to the NSLS 

in September 1997, after an acceptance test in Germany. 

Operations commenced on the X-Ray Ring on 

January 23, 1997 at 350 mA. On February 1, there 

developed a water-to-vacuum leak in the RF1 cavity, 

causing the cavity pressure to jump from the 10-lo Torr 

range to the mid 10-07Torr range. Helium leak detection 

failed to identify which water-cooled component was 

leaking. At an emergency user meeting the decision was 

made to replace the RF coupling loop, the most likely 

defective component, during the February 10 - 1 I studies 

period and to continue operating at 250 rnA until that 

time using the other three RF cavities. The repair was 

carried out on February loth, followed by RF and beam 

conditioning on February I 1 th. Operations resumed on 

schedule at noon on February 12th. By February 15th, 

conditioning with operational beam had lowered the 

cavity pressure to the 1 0-O9 Torr range. 

In February 1997, an effort to fully characterize the 

beamline shielding requirements at 2.8 GeV commenced. 

Studies periods were utilized for radiation surveys by 

S&EP personnel to record in detail which beamline 

components and hutch walls require additional shielding. 

The initial surveys were completed in April so that users 

could make use of the May shutdown period to shield. A 

21,000 pound shipment of (3'x5'~1/16") sheets was 

delivered early in May, and a work area was set up outside 

the NSLS Stockroom for cutting the lead sheet. 

Procedures for handling the lead and discarding lead 

scraps, contaminated covering material, gloves and aprons 

were outlined in the April 16, 1997 NSLS ES&H 

Highlights. Users were encouraged to begin their 

shielding efforts early because obtaining final operational 

approval of the shielding was, in many cases, an arduous 

process requiring a series of radiation surveys followed by 

shielding efforts. Beamline personnel continued to use 

dedicated studies shifts to survey the effectiveness of 

additional lead shielding for 2.8 GeV operation. To 

expedite this process, beamlines having sufficiently low 

radiation levels were put on a list to operate in a "self- 

monitoring" mode. In this mode users are able to 

immediately check newly-installed shielding and make 

required modifications. During the 2.8 GeV operations1 

survey week of September 23-29,1997, the X-Ray Ring 

operated reliably with 230 mA fills. By the end of the 

week there were 34 beamlines operating in either the self- 

monitoring mode or in an "approved" mode after a final 

survey indicated that all beamline components had levels 

less than 500 cpm on a Ludlum pancake Geiger counter. 

Self-monitoring lines were expected to continue their 

shielding efforts to the satisfy the 500 cpm requirement. 

During FY 1997 the horizontal and vertical digital 

feedback systems were prepared for operation. However 

these systems were not implemented because of a large 

horizontal chamber motion during a typical fill. To track 

the chamber motion, sensor stands will be installed and 

data acquired during operations from high sensitivity 

LVDT probes mounted on stands at various PUE 

locations. Carbon fiber tubes for the stands are expected 

to arrive in January 1998. Data acquired from the 

horizontal sensors measuring the ring chamber motion 

at each of the 48 PUEs during X-Ray fills, will be input 

to the digital feedback system to correct for this motion. 

During 1997 the algorithm of the global harmonic 

feedback system was changed to give a factor of two 

improvement in orbit stability. The programmable boards 

for the analog global feedback system were received. Initial 

studies were conducted on the low emittance lattice with 

the low emittance lattice response matrices successfully 

downloaded onto these boards. Studies of the new lattice 

will continue in order to check orbit stability and to 

increase the fill current to 440 rnA. 

The major X-Ray Ring task during the May 1997 

shutdown was the removal of the PSGU(Prototype Small 

Gap Undulator) from the XI3 straight and the installation 

of the IVUN(1n-Vacuum Undulator) which is a short- 

period magnet array (30.5 periods, with an 1 1 mm period 

length) developed at SPring-8. The associated vacuum 

chamber and mechanical systems were developed at the 

NSLS. IVUN is designed to produce 4.6 keV radiation 

in the fundamental, at a magnet gap of 3.3 mm, with 

useful photon fluxes in both the 2nd and 3rd harmonics. 

The magnet gap is adjustable between 2 mm and 10 mm. 

A number of other shutdown tasks were completed. 

Upgraded beryllium windows were installed on the X4C 

and X6B beamlines. The remaining 13 upgraded 

beamline windows required for high current (438 mA) 

operation will be installed during maintenance periods 

and the December 1997 shutdown. Safety metering

transformers were installed on 480 Volt RF and magnet 

power supplies to verify isolation from source lxnver hcforc 

carrying out rcpair work. Also, the fill1 cooling capal~ility 

of the NSLS high pressure and low prcssurc copper \vatcr 

systems was restored after heat cxcliangcrs for these 

systems wcrc clcancd o ~t. Finally, the helium cryotransfcr 

line for tlic XI 7 ~u~crconducting wiggler was replaced. 

allowing the XI 7 hcamlincs to resume operation on June 

9th. A Icalting transfer line had shut tlicsc lines do\\.n 

since thc middle ofApril. Subst;lntial improvements wcrc 

.- 

made on the X17 cryogenic system. I lie two hclium 

supply and rcturn transfer lines to the refrigerator were 

totally rchuilt, tl~creby eliminating an erratic heat leak. 

Anothcr major problem was solved when a nictal chip 

was I-cmovcd from the autofill valve sear to the mapet 

cryostat. Aftcr thcsc repairs the system ran smoothly 

Following the installntion of the TVUN (In-Vacuum 

UNdulntor) in the XI 3 straight section during tlic h4;1y 

1997 shutdown, there follo\vcd a commissioning period. 

Initial conditioning \1..a carried out at a gap of 10 mm. 

Aftcr 10 amp-hr of conditioning tlic prcssurc at 330 mA 

\vas 7.1 n7hrr which further dccrcascd to 1 nl'orr after 

230 amp-hr. During studies periods, IVUN operated 

with magnet gqx hctwccn 10 mm and 3.2 mni. At a gap 

of 3.2 mrn tlic ring lifctimc dccrcascd to about 12.7 hr, 

corresponding to a partial lifctimc contrihtion of over 

100 hours. Tlic olxcrvcd p110ton q~cctrum from tlic 

IVUN was mcasurcd in the XI 3 hr~tcli using a singlc 

crystal spcctrornctcr. The agreement betwccn the 

oI,scrved and theoretical spectrum was good. 'I'lic 

brightness at the peak of tlic 4.6 kcV fundnmcntal was 

3x1 0'- I~hotons/~c/0.25amp/mm'/nirad? 10.1 ?h 

band\vidtli. Also, during FY 1997 the X 13 I~lliptic;llly 

Polarized \X4gglcr (F,PW) was ahlc to operate at 2,23, 

and 100 Hz ~vitli tlic x-ray orbit compcns:ltcd so t1i;it 

other bcamlincs wcrc not affected. W

Normal Operating Energy 

Maximum Operating Current 

Lifetime 

Circumference 

Number of Beam Ports on Dipoles 

Number of lnsertion Devices 

Maximum Length of lnsertion Devices 

hc(Ec) at 1.25 T (B) 

&(Ec) at 5.0 T (W) 

B(p) 

Electron Orbital Period 

Damping Times (2.584 GeV) 

Touschek (2.584 GeV, 0.25A) 

Lattice Structure (Chasman-Green) 

Number of Superperiods 

Magnet Complement 

32 Sextupole 

Nominal Tunes (vx,v,) 

Momentum Compaction 

RF Frequency 

Radiated Power for Bending Magnets 

RF Peak Voltage 

Design RF Power 

v, (Synchrotron Tune) 

Natural Energy Spread (o,/E) 

Natural Bunch Length (20) 

Number of RF Buckets 

Typical Bunch Mode 

Horizontal Damped Emittance (EJ 

Vertical Damped Emittance (EJ 

Power per Horizontal Milliradian (0.25A) 

Arc Source Parameters 

Betatron Function (Px,PV) 1.0 to 3.8 m, 7.9 to 26.5 m 

Dispersion Function (qx,~l) 0.47 to -0.11, -0.39 to 0.22 

2.584 CeV 

0.30 amp (1012 e-) 

-20 hours 

170.1 meters 

30 

5 

< 4.50 meters 

2.23 A (5.6 keV) 

0.56 A (22.2 keV) 

1.25 Tesla (6.875 meters) 

567.2 nanoseconds 

T~ = T = 6 msec; ze = 3 msec 

Y 

Q 27 hrs (v,, = 700 kV) 

Separated Function, Quad Triplets 

8 

{ 16 Bending (2.7 meters each) 



(0.20 meters each) 

9.15, 6.20 

0.0056 

52.88 MHz 

144 kW/0.25 amp of Beam 

1000 kV 

400 kW 

0.002 

8.6 x 

10.5 cm 

30 

25 

1.0 x lo-', meter-radian 

1 x 10-lo meter-radian 

23 Watts 

ax,^ = -fir x,y/2 -0.49 to 1.62, -3.4 to 4.5 

yXjy =(I +ax,Y)/Px,y 

Source Size (ox, o,) 

0.952 to 0.962 m-l, 0.81 to 0.52 m-I 

371 to 565 pm, 27 to 49 pm 

Source Divergence (ox,o,) 439 to 324 prad, 8 to 7 prad 

Insertion Device Parameters 

Betatron Function (Px, P,) 1.60 m, 0.35 m 

Source Divergence (ox, o,) 260 prad, 35 prad 

I

VUV BEAMLINES 

Roger Klaffky 

Beamline Technical Liaison 

There were a number of technical bearnline 

improvements on the VUV Ring during FY 1997. 

Rebuilding of the U2A bcamline for high-pressure 

infrared spectroscopy and for infrared micro-spectroscopy 

was underway. The U1 /U2 dipole chamber chamber was 

modified during the winter 96-97 shutdown to provide a 

solid angle of 100(H) x 48(V) mradians on the U2 port. 

Extraction optics consisting of a new mirror box and 

diamond window were designed and built at the NSLS. 

A new Brulwr IFS 66 V/s FT-IR instrument was 

purchased and a new Br~~ker TI, IR microscope was tested 

and implemented for samples in small diamond cells. The 

optics in both of these instruments was modified for 

synchrotron radiation measurements. In addition, a new 

large working distance microscope was designed and built. 

Bcamlinc U3A was in an intensive recommissioning 

phase involving hardware upgrades, nionochromator 

development, bcarnlinc calibration and diagnostics. 

Hardware modification included reconfiguration of the 

MO mirror chamber, a beamline computer upgrade, 

installation of RF reactors for cleaning XUV optics, 

installation of a new filter assembly, and monochromator 

operations. Several sets of monochromator crystals and 

multilayers wcrc mounted and aligned. These included 

matched pairs of beryl, Na P alumina, Mo/Si and W/Si 

multilayers. Harmonic content was negligible above 1000 

eV. Second order harmonics abovc 800 eV were 

controlled with filters. Monochromator motors wcrc 

replaced and motor translators modified to allow for a 

programmable holding torque. 

The microscope from U2B was nloved to U4IR 

where it was ilscd for several experiments. 

As part of the DOE Scientific Facilities Initiative 

(SFI) spherical gratings and a moveable exit slit will be 

added to the U4A bcamline, replacing the present toroidal 

gratings and fixed slits. A conlputer upgrade was in 

progress and in the ARP chamber, a new cluster of metal 

evaporators and a thin film thickness monitor were 

installed. 

The U4R SGM-based bcarnlinc optics were 

commissioned, as was the UHV c1i;lmhcr 2nd growth 

capabilities. The U5UA heamline and its spin-resolved 

photocmission end station began full operation in Janu;~ry 

1997. 

A full General User program hcgnn at the new U7A 

S6M soft x-ray photocniission and spectroscopy benmline. 

Installation and commissioning of a high pressure surhcc 

chemistry charnbcr on top of the chemistry end-station 

took place. 

The former U9A bearnlinc was removed and 

were made to install an NS1.S machine vacuum 

R&D bcanilinc to measure photon-stimul;ltcd desorption 

of materials and coatings for advanced UHV construction. 

Tko modified ring \racuum cliamhcrs wcrc instnllcd 

during the Spring 1996 shutdown to provide a 1 00(H) x 

48(V) mradian solid angle IR beam at the U10 port and 

a 90(H) x 90(V) mradian solid angle IR beam at the 

U 12IR port. The U 1 OA bcanilinc was under construction 

in FY I997 and is intcndcd to opcratc with a rapid Scan 

Brukcr IFS 66Vls FT vacuum spccrromctcr over the r;~ngc 

of 1.2 mcV to 3.3 eV. 'I'hc U121R beamline was in the 

final stages of construction with the UHV mirror tanlt 

installed on the ring and most of the bcani-tr;insport 

follo\ving the diamond window complctc. Two Ill 

spectrometers were installcd: a E~r-infi.;~rcd I;~tiicllar grating 

interferometer for spectra bctwccn 2 and I00 cm-' and a 

Brukcr IFS 1 13V for the 50-1 0,000 cm-' rangc. 

During 1997 redesign and reconstruction of 

bcamlinc U12A continued, which will result in a 

conversion from a TGM into a 'SCMISGM bcariilinc 

covering the 100-800 cV photon energy range. Upgr;idcd 

electric service was installed. Optics for this conversion 

will arrive in 1998. 

The U13UR hcamlinc was i~ndcr construction in 

1997. This bcamlinc is devoted to UVlVUV spectroscopy 

in the 5-30 cV range. The U 13 i~ndulntor/wig~lcr sourcc 

can be directed to either: (1) a focused white liSht hranch, 

or (2) a high energy resolution monoclirornntic blnnch. 

The PRT mcnihcrs acquired DOE SF1 funds to design 

and construct a high resolution ARI'ES chamlm.

At U15 the beamline computer control hardware 

and software were upgraded as was the vacuum system. 

The Ul6B ERG monochromator and refocusing optics 

were restored to an operating condition. 

X-RAY BEAMLINES 

The X1A beamline was rebuilt during the second 

half of 1996 and started operation in the new 

configuration in February 1997. The rebuilding resulted 

in two independent branches, improved energy resolution 

and flux, and additional space. A large effort was directed 

towards commissioning of the cryo-scanning transmission 

x-ray microscope (Cryo-STXM) on the inboard branch 

line. This instrument images frozen hydrated biological 

specimens at near liquid nitrogen temperature, where 

radiation damage does not manifest itself even after 

repeated imaging. Tomography data sets were taken with 

this apparatus. Cryogenic capabilities were implemented 

in the x-ray holography chamber, which is also used on 

the inboard branch line. 

Two new experimental facilities were implemented 

on X1B. A soft x-ray emission (SXE) spectrometer was 

commissioned as was a new spin polarization facility based 

on the use of a Scienta hemispherical analyzer and a micro- 

Mott spin polarimeter. This will allow high resolution 

spin polarized photoemission studies in the soft x-ray 

range. 

At X3A electric wiring in the monochromator 

assembly was redesigned to eliminate cross-talk between 

the A1 and A2 monochromators. Also, new operating 

software for a Pentium PC was under development in 

collaboration with the staff of the 15-ID station at the 

APS. 

On X4A a new Raxis-IV automated detector was 

installed and tested. The X4C beamline approached 

completion. First light was taken into the hutch in 

February 1997. The Windows 95 based VME motion 

control system began operation, controlling close to 30 

motors. The horizontal focusing monochromator, based 

on an NSLS design, was commissioned. In the future, 

the monochromator will be completely characterized and 

The New DOW / NIST Materials Characterization Facility at Beamline U7A. 

Back, left to right: Arnie Moodenbaugh (DAS), James Wood (Osmic, Inc.), Raj Korde (IRD), Michael Hart 

(Chairman, NSLS), Gabrielle Long (NIST), Steve Hulbert, and Qing Yi Dong (NSLS). 

Front, left to right: Daniel Fischer (NIST), Benjamin DeKoven (DOW), Stephen Freiman (Chief, Ceramics Division, 

NIST), Lyle Schwartz (Director, Materials Science 8 Engineering, NIST), and Robert Bubeck (Synchrotron 

Coordinator, DOW).

a vcrtical focusing mirror will be installed. 

There were substantial improvements at the X5 

Laser Electron Gamma Source (LEGS) heamline. The 

first phase of the Spin Asymmetry dctector array (SASY) 

was installed in the X5 expcrirncntnl area. The dctector 

array comprises the XTAL BOX (an array of Pb-glass 

Cercnkov counters. A prototype of the in-beam Gas 

Cerenkov counter for tlic rcjector of electron pair 

production events online was also irnplcrnented. The 

XTAL BOX provides good photon resolution (- 1006) for 

high energy photons as all azimuthal angles and at polar 

angles of70 to 145 degrees in the current configuration. 

Thc forward wall ofplastic scintillators provides coverage 

for nucleons from 10 to 35 degrees with a 40%) efficiency 

for the dctcction of neutrons. The plastic bars and Pbglass 

wall arc capable of detecting high energ photons 

with moderate energy resolution, and angular resolution 

on the ordcr of 6 degrees results in an overall acceptance 

for reconstruction of neutral pions of 50%. The complete 

r~str~~ct~~ring of tlie X5 lascr hutch was underway in order 

to accommod;lte the energy q ~~dr~~plcd lascr designed 

and constructed by Frascati and RNI,. This Nd-YIJ ring 

laser delivers 2 Watts of ultra-violet light at 263 nm. The 

combination of the new ring laser and 2.8 GeV electrons 

will increase LEGS energies to 470 MeV. The 

dcvcloprncnt of tlic new spin- polarized HD ice targct 

yielded an opcrablc full-size targct, albeit in a limited 

mode, of 51 94, H polarization and I I ?h D polarization. 

Aftcr prtinl aging, tlie targct was disengaged from the 

dilution rcfrigerator, raised with the cold-transfer 

assembly, reinserted and the rctaincd polarization 

mcasurcd. This was a milestone in the target development. 

The HD production equipment has been improved and 

operated to produce large amounts of targct quality HD 

with only a single distillation starting from 98% pure 

commercial HD. The in-beam cryostat was constructed 

at Orsay. 

AtX7B it was discovered that the heamline Zcrodur 

filsed silica premirror had deteriorated due to exposure 

to white-beam synchrotron radiation. The heamline was 

reconfigured to run without a premirror while a new 

coated silicon crystal mirror was being manufactured for 

installation during the Deccmher 1997 sli~~tdown. There 

was also progrcss in addressing monochromator heatloading 

problems. Water flow to the crystal holders was 

improved, and graphite filters were purchased. A new 

MAR 345 mm imagc-plate based detcctor \\.as purchased. 

Work was in progress on the design and construction ofa 

MAR-based detector system, incorporating a precision, 

variable sample-to detector-distance table, a new universal 

sample lioldcr installation and a new set of fi-ont-end bean1 

positioningltracking devices. 

On the X9B beaniline a MAR image plate detector 

and a Silicon Graphics computer were purchased to 

enhance tlie collection of protcin cryst;~llogr;lpliy datil. 

Implcmcntntion of a nciv computer control system and 

monochromator modifications were also undcrwny. 

Funding was secured for completion of a st;lre-of-thc-:1rt 

protein crystallograpy station on the X9A bcamlinc. This 

work will begin in FY 1998. 

A number of upgradcs \verc coniplcted or underway 

on XI IA, largely as a result of DOE SF1 funding. A 

sagitally-focusing system was purchased which will 

provide at least n three-fold increase in intensity. A Rhcoated 

vertical Iy collimating Si mirror was purchased for 

installation during the Deccmhcr shut down. A ncw 

Huhcr goniornctcr \vas purcli:~scd and a new computercontrolled 

slit asscmhly \v;is installed in tlic hutch. Finally, 

a 13 element solid state dctcctor was oht;iincd. 

At X12R a custom built phi-spindlc was 

*. 

implemented for the sample goniostat. I lie spindle 

mount incorporates a high n~a~nification video 

microscope. An Oxford Cryosystcms Cryostrenm cools 

the sample. Funding from DOE SF1 funding allowed 

the purchase of a large aperture Area Detector Systenis 

Quantum-4 CCI) array dctcctor. The array generates an 

image consisting of 2300 x 2300 16-bit pixels, with ;I 

readout dead time of approsin~atcly 9 seconds. Thc 

dctcctor was tested in July 1997, and has become the 

principal crystallography dctcctor. A MAR scanncr is 

used for experiments requiring greater coverage and 

readout dynamic range. A series of hoists and surhcc 

plates (called the "detcctor selector") was installed in the 

hutch roof permitting rapid dctcctor chairs. A 

Reo\vuIf.I,inux coniputational cluster wxs installed with 

a I00 MHz Ethernet connection bct\vccn XI 213, XI 2C, 

and X25. 

The XI 3 port uses either the 1n-V;lcuutn Undulator 

(IVUN) or the Illliptically Polarized Wiggler (1-PW) as a 

source. During FY 1997, full orbit compensnrion was 

achieved when the F,PW changes the photon pol;lrization 

at a 2,23, or 100 Hz rate. A soft x-ray SGM 

monochromator \vxs designed and ordered for the X13A 

branchline using SF1 fi~nds. Commissioning will occur 

in 1998. 

Reamline X14A initiated an upgrade of the mirror, 

monochromator and computer hardnlare. A new mirror 

with a factor of three lower surface roughness and 

insignificant figure error was procured with I30E SF1 

funds. The improved mirror should deliver about 25% 

more flux at I 0 IK~V and a factor of 2 lower crnitt;incc nt 

the sample. New crystals, with three times the uscable 

surface area for focusing synchrotron radintion, will allow 

X14A to focus up to 15 mradinns of 1iorizont;ll beam 

di\wgcnce. X14A \vx designated a test-hed for the 

development of Iinrdwnrc and softwnrc to allow remote

control of major DOE facilities. Towards this end, plans 

were made for a migration to a PC-based computer system 

running SPEC, and installation of cameras and 

telecommunication hardware. 

At X16C a front-end white-beam aperture (with 

slits and a pinhole) was designed and installed for 

microprobe and micro-XAFS applications. A permanent 

setup for XAFS experiments was also built. 

At X17C a pair of Kirkpatrick-Baez mirrors was set 

up for focusing white x-ray beams at a glancing angle 

incidence to a 3-30 micron spot. Clean up slits were 

used to eliminate the tail of the focusing beam. A 130 

element detector was used to permit simultaneous 

collection of energy dispersive x-ray diffraction at different 

angles, an important configuration for high pressure 

elastic properties studies. A new 12 degree cone double 

receiving slit system was developed for the multi-element 

detector to reduce background and increase the signal- 

to-noise ratio. An optical microscope for precise and 

convenient alignment was integrated into the diffraction 

system. 

At the XI 9A a white beam damaged Zerodur mirror 

was replaced with a new silicon mirror. An improvement 

in throughput of more than a factor of 10 was achieved 

as well as a significant decrease in focused beam size. 

Additional diagnostics were installed to facilitate 

alignment. The successful implementation of InSb 

crystals took place, and the possibility of using 

monochromator crystals with larger d spacing to permit 

studies at the A1 edge is under consideration. At X19C 

an analyzer axis was designed for the defector arm to 

enable harmonic contamination analysis of white beam 

topographs. Implementation of the axis was underway. 

On the X2OA,B, and C beamlines data-acquisition1 

analysis computers were replaced with IBM RSl6000 

computers running the AIX 3.2.5 operating system. The 

motor controlling and data acquisition program SPEC 

was upgraded to version 4.03.01. A UPS for these 

computers, along with software capable of shutting down 

the AIX operating system automatically during a power 

outage, was purchased and installed. At X20B, a 

computer-controlled monochromator focus and tilt DC- 

motor problem was solved on the bench and plans were 

made to complete an X20B monochromator upgrade with 

the installation of these motors. At X2OC a new focusing 

mirror purchased by the NSLS with DOE SF1 funds was 

installed, improving the vertical focus by a factor of three. 

A new set of synthetic SiIW multilayers also improved 

the focused spot size. 

Normal maintenance and upgrades were carried out 

at X22A,B and C including installation of a LINUX 

operating systems. Pt-coated Si mirrors were purchased 

for these beamlines using SF1 funds with installation to 

occur in 1998. The X22B slit assembly was upgraded, 

and SF1 funds were used to upgrade the liquid surface 

spectrometer, including addition of a UHV chamber for 

liquid metals. 

The X23A2 beamline was upgraded with the 

installation of new ion chambers, a new Macintosh Power 

PC 86001200, LABVIEW data acquisition software and 

a computer driven exit slit. The two-reflection Bense- 

Hart-type SAXS at X23A3 was temporarily replaced with 

a four-reflection instrument. Significant reductions in 

background, and concurrent improvements in signal-to- 

noise, were observed. Testing of the instrument continues. 

At X23B it was discovered that the collimating 

mirror was not coated with Pt as requested. Investigation 

into this problem led to the discovery that several mirrors 

at the NSLS has been mis-coated (sometimes with 

germanium, rather than platinum). In May 1997 a 

properly coated mirror was installed resulting in a 

dramatic increase in flux. The monochromator 

microstepper controller was replaced to reduce 

maintenance and correct a problem with missing steps. 

PZT drivers were added to allow realtime adjustment of 

chi and a larger theta range. Computer equipment was 

also upgraded. 

There were substantial changes at X24A as new 

applications using the x-ray standing wave (XSW) 

technique were added to the previous soft x-ray gas 

spectroscopy capability. New UHV chambers were made 

available for back-reflection XSW. DOE SFI funds were 

used to purchase a hemispherical analyzer for electron 

spectroscopy. The computer controlling the 

monochromator was replaced with a PC operating in 

LINUX or Windows. New two-axis (theta and chi) PZT 

correctors were installed on several monochromator crystal 

pairs. This will stabilize the focused beam position. Also, 

an InSblKDP crystal pair was added to permit operation 

down to 1800 eV with a resolution of 0.5 eV or better. 

At X25 SF1 funds were used to purchase a new 34.5 

cm diameter imaging plate system for macromolecular 

crystallography, and diffraction cryostats for materials and 

condensed matter x-ray scattering and spectroscopy 

applications. A new pair of monochromator multilayers 

was obtained and utilized in several experiments. 

During FY 1997 the X-ray Computed 

Microtomography apparatus was moved from X27C to 

X27A. A multilayer monochromator was installed inside 

the X27A hutch to allow microtomography on biological 

samples in the 4 to 12 keV range. A new cooled CCD 

camera was integrated into the setup, increasing both the 

resolution and the size of samples that can be analyzed. 

The size of data sets that can be acquired grew due to 

new data collection hardware and software, and the 

reconstruction time reduced through the use of 8

multiplexed I'entium processors in BNI, CCD. In 

January the newly established Advanced I'olymers PRT 

was given approval to instrument and operate X27C for 

real time simi~ltaneous small and wide angle X-ray 

scattering (SWAX) experiments. During the 

commissioning phase a double-multilaycr (silicon1 

tungsten) monochromator, a three pin-hole SAXS 

collimation system, and a simultaneous SAXSIWAXD 

camera were installed. The double-multilaycr 

nionochromator increased the x-ray flux by a factor of 10 

compared to a convcntionnl douhlc-cryst;ll 

monochromator. The hcnmlinc l qan initial opcrntions 

in July. 

The x-ray pinliolc carncrn oti X28C continued to 

report data to thc Control Room and history progr;lnis 

on a real-time b:~sis. Cooling for stepping motor 

operation, and a host of signal and prc-:imp cnl>lcs wcrc 

wired for i~sc. Some components and fc.;ltr~rcs of thc 

camera system were also improved. .

Beamlin e structure of the complex between oncogenic protein Ras and the Ras- 

interacting domain of RalCDS (RalCDS-RID) has been studied by x-ray crystallography. 

The structure of the complex will provide crucial information on Ras' interaction with its 

binding partner at an atomic level. Since the mutant forms of Ras are involved in 30% of 

human cancer and Ras' function is carried out through its effectors, the spatial location of the 

key interface residues may assist in identifying small molecules that are capable of disrupting 

this interaction and thus provide insights for the development of anti-cancer drugs. The 

crystal has a P212121 space group, with a=75.648, b=78.256, c=87,313. The complex 

crystallizes as a heterotertramer with two active Ras molecules and two RalCDS-RID 

subunits. (See also Abstract on page B-220.) 

L. Huang, F. Hofer, C.S. Martin, and S-H. Kim (U. California at Berkeley)

THE NSLS SOURCE DEVELOPMENT LABORATORY 

Erik D, Johnson 

SDL Project Manager 

The Source Development Laboratory (SDL) was 

created as a project within the National Synchrotron Light 

Source as a way to serve its user community by developing 

sources for the next generation of synchrotron radiation 

based research. The path to the founding of the current 

SDL was based on a strong interaction between potential 

users of advanced sources of light, and the NSLS. It is 

possible due to innovative developments in accelerator 

physics by NSLS staff and experimental achievements at 

the Accelerator Test Facility (ATF). Another element that 

makcs the SDL so readily possible is the wealth of 

infrastructure and equipment already available. 

The focus of the SDL is on joint development df 

both the radiation source and science program based on 

its capabilities. Generally speaking, the project is 

developed to fit within the framework of research 

supported by the DOE office of Basic Energy Sciences. 

Source Development Laboratory: 

Ultraviolet Project Free Electron Laser 

// 

.-- 

H C. 

. .. 

11:Sapp 

(i~rn Linnc EM D Wiggler Experiment 

Wavelengths down to 75 nm 

Pulse Lengths down to 4 fs 

Multi-color Experiments 

It's sister facility, the ATE provides significant accelerator 

expertise employed by the SDL. However the active beam 

physics experimental program of the ATF precludes its 

use as a UV FEL source for research. Throughout the 

SDL project, we have made every possible effort to draw 

on existing resources and the strengths of coilaborators 

from many interested institutions. 

Early on in the process of evaluating alternative 

source technologies, the vacuum ultraviolet was identified 

as a promising area for development. Although there are 

many FEL projects in the world, to date, all the successful 

user facilities have been based on oscillator designs. This 

places very great demands on the optical elements of the 

cavity in terms of reflectivites which would be difficult to 

routinely achieve in the ultraviolet. An alternative 

approach would be to run a high current electron beam 

through a long undulator in a single pass. Many projects 

1- C' 

have been started based 

on this Self Amplified 

Spontaneous Emission 

(SASE) or startup from 

noise model. 

While SASE may 

get to shorter 

wavelength without 

oscillator optics, it is 

essentially amplification 

of noise which, from the 

standpoint of users of 

the radiation, may have 

serious experimental 

consequences. For this 

reason, Li-Hua Yu and 

his collaborators have 

developed the approach 

adopted at BNL for 

creating a seeded 

amplifier FEL. In 

addition to providing 

superior stability, this 

approach allows the

generation of high harmonics of the fundamental 

radiation used for the seed. This means a visible seed 

laser (and its properties) may be amplified and frequency 

multiplied, in principle, well into the ultraviolet. 

The figure gives a qualitative picture of how the 

SDL FEL works, and provides some insight into its 

potential power as an experimental tool. A "conventional" 

Ti:Sapp laser system is frequency multiplied to stimulate 

emission of electrons from the cathode of the RF gun. 

This gun ~rovides a high peak current, low emittance 

pulse of electrons which is accelerated by a SLAC type S- 

band linac. For seeded beam operation, these electrons 

pass through an energy modulation wiggler (EM) while 

interacting with a portion of the laser beam from the 

laser driving the photocathode. In the seeding process 

an energy modulation is introduced on the electron beam 

which is converted into a spatial modulation by a 

dispersive magnet (D). The already microbunched beam 

is introduced to the amplifier wiggler which may be tuned 

for gain either at the fundamental seeding energy, or a 

higher harmonic. 

This arrangement can be readily viewed as essentially 

a high gain amplifier and frequency multiplier for the 

seed laser. The FEL output will then reflect characteristics 

of the seed laser such as wavelength, pulse length, 

bandwidth and energy chirp. This property makes the 

seeded beam FEL a very high quality tool for research 

applications requiring stability and short wavelengths. For 

our long term goal, we have our sights set on performing 

experiments with an FEL producing UV radiation at 

wavelengths below 100 nm in pulses as brief as 5 fs with 

peak power ranging to over 100 GW. There are, of course, 

a few intermediate steps that need to be taken. 

We are working hard on bringing up the SDL 

accelerator now, and are hoping to have the linac 

operational in mid 1998. The FEL experiments will come 

as rapidly after that as time, determination, and budget 

allow. As the effort has intensified a great deal of work 

must be pursued in parallel. To make this possible we 

have formed a management team. 

Jim Desmond and Nick Gmiir are responsible for 

finding ways to make sure the project gets done with the 

budget we have, and meets all the requirements to run in 

a safe manner; no small tasks these days. For the other 

team members, the project areas listed are really an 

inadequate representation of the wide range of 

contributions and responsibilities within this small 

project. For example, in addition to specifying and 

commissioning the SDL Laser systems, Lou DiMauro 

(with his joint appointment in Chemistry) brings his 

expertise in atomic physics and the broader knowledge 

The SDL Management Team 

The following individuals are bringing their 

expertise to the task of bringing the SDL "on- 

line". 

Jim Desmond 

Lou DiMauro 

Nicholas Gmiir 

Bill Graves 

Richard Heese 

Erik Johnson 

Xijie Wang 

Li-Hua Yu 

Fiscal Management 

Laser Physics 

ES8H 

Diagnostics 8 Controls 

Linac Systems 

Project Manager 

Electron Gun Systems 

FEL Physics 

of conducting experiments with lasers to the project. 

Besides developing new diagnostics and coordinating the 

rebuilding of the accelerator control system, Bill Graves 

did extensive simulations of the compression system and 

beam transport. Through this work, he developed the 

current linac design that includes pulse compression and 

a focused interaction point for Thompson scattering 

studies; enhancements that significantly extend the 

potential of the machine. 

Richard Heese brings extensive experience in linac 

technology and development to the project. He has also 

assumed the responsibility for supervising the 

reconstruction and upgrade of the SDL linac and has 

taken on the difficult task of coordinating the technical 

work in bringing the facility up. Xijie Wang brings not 

only the gun technology to the project, but his experience 

of coordinating the operation of the ATF. Li-Hua Yu not 

only developed the basic physics for our planned FEL, he 

is leading the High Gain Harmonic Generation (HGHG) 

experiment at the ATF and applies his experience to the 

development of the SDL program. 

We also have a project advisory panel, consisting of 

Ilan Ben-Zvi, Jerry Hastings, and Sam Krinsky who bring 

a broad perspective to the problems of bringing up a new 

accelerator based source. In actually accomplishing 

anything, the broad participation from every section of 

the department has been critical. This has been especially 

true of the electrical and mechanical groups who are 

responsible for the majority of the visible progress to date. 

All in all people have been attacking their tasks with an 

enthusiasm that lifts the whole project. We hope to be 

seeing some of that work coming to fruition in the next 

year. To look at the project in more detail or to keep 

abreast of the latest developments, visit the SDL web page 

http://www.nsls.bnl.gov/BeamRD/Erik/SDL.html. 

.

has a high density in 6-D phase space. To achieve high 

brightness beams, it is necessary to master the production 

of such beams in special electron guns, to develop 

diagnostics that provide information of the 6-D 

distribution of electron bunches on sub-picosecond time 

scales, to control the 6-D distribution of the bunch in 

various ways and to be able to accelerate the electrons to 

high energies without diluting the brightness. 

NSLS scientists working at the ATF measured the 

slice emittance of a 10 ps electron bunch with a 1 ps 

resolution, achieved an unprecedentedly high 6-D 

electron phase-space density and directly measured 

electron bunching on an optical scale. Another diagnostic 

under development at the ATF is tomographic analysis 

of the distribution of electrons in transverse phase space. 

The next step is to pursue non-linear emittance 

compensation. Laser photocathode RF guns have 

provided a major improvement in the brightness, which 

was further enhanced by the introduction of (linear) 

emittance compensation. The dream of another major 

improvement by the introduction of non-linear 

corrections has been brought within reach by the 

development of the slice-emittance diagnostic and the 

availability of lasers with longitudinal pulse shaping. 

Key to our plans is the development of sub- 

harmonically seeded FELs in which harmonic generation 

converts a laser seed to much shorter wavelength radiation. 

A proof-of-principle High-Gain Harmonic-Generation 

(HGHG) FEL experiment is planned to be carried out at 

the ATF in the infrared using a CO, laser seed. Both the 

SASE and HGHG work will be extended into the VUV 

at the SDL, using the NISUS wiggler. These experiments 

at the ATF and the SDL are milestones, not just for the 

BNL program, but also for other projects like the proposed 

(Top, from left to right) John Skarita (Mechanical Section), Marc Montemagno (Electronics), and lgor 

Pogorelsky (Lasers). 

(Middle, from left to right) Bob Harrington (Mechanical and Optical Systems), Joe Sheehan (Electrical 

Section), Robert Malone (Computer and Control), Bill Cahill (Technical Supervisor and Users' Coordinator), 

and Marcus Babzien (Lasers). 

(Bottom, left to right) Xijie Wang (Accelerator, gun, diagnostics), llan Ben-Zvi (Head of ATF), and Vitaly 

Yakimenko (Accelerator, gun, diagnostics).

Linear Coherent Light Source at SI.AC and tlicTeslaTest 

Facility FEL at DESY, Hamburg. The goal of these efforts 

is basic experimental research in FEI, physics, which has 

been reconimended by numcrous panels and review 

committees as an imperative on the way to developing 

short wavelength FELs. An initial success in this program 

has been the ATF measurement of SASE at Ipm and 

0.63 pm. At the SDL, it is planned to utilize the output 

of the FEL to carry out prototype experiments to gain 

experience in providing FEL beams to users. 

One of the special features of the measurement at 

the ATF is that tlic short wavelengtli was reached at a 

relatively low electron beam energy (34 MeV for tlic 1 

micron measurement). To get gain with an FEI, at a 

lower energy, tlic beam emittance must be small. It is 

easy to show that the bcam energy required for obtaining 

a particular FEL wavelength is proportional to tlic heam 

emittancc. The wiggler length is proportional to 

something between the emittancc and the emittance 

squared, depending on tlic wiggler strength parameter. 

Since tlic complexity and cost of an electron linac and a 

wiggler arc proportional to the length of these devices, 

an improvement of one order of magnitude in the electron 

bcam emittance will reduce the cost by one ordcr of 

magnitude! Such a reduction has taken place in the last 

decade with the introduction of emittance compensation 

techniques to laser-photocathode RF guns, and that is 

the driver behind the recent activity in short wnvelength 

FELs. Another order of magnitude will place an x-ray 

FEL within reach of evcry laboratory. 

Another feature, made necessary by the low energy 

is the use of a very short period undulator. It is clear that 

to make use of lower emittancc electron beams short 

period undulators must be developed. The SAE 

measurement at the ATF was made with an undulator 

built by MIT with a period of 8.8 mm. Another 

undulator, with the same period hut using a 

superconducting magnet, \ws dcvclopcd ly the NS1.S. 

These are the shortest period undul;~tors in actual use 

an>~vhcrc. 

The ATF and the NSIS arc in the ccntcr of the 

national effort to develop short wnvclcngth Fl

Beamline U2B: Localization of drug metabolites within human hair is important in 

determining the pharmacokinetics of drug incorporation in hair. This information is critical to 

validate drug testing data from hair. Doped hairs compared to reference hairs show spectral 

differences with bands corresponding to the frequencies of the drug of interest. Analysis of 

the patient hairs from cocaine and heroin abusers showed that the drug was concentrated in 

the medulla of the hair. When the patient had non-medullated hair the drug was not present. 

At right is a topical graph of a hair from the synchrotron infrared microscope, mapped for the 

primary frequency band for cocaine in a drug abuser's hair. The graph shows the drug to be in 

its highest concentration in the central portion of the hair and the lack of drug absorption in 

parts of the central portion of the hair correlates to areas where the medulla was fragmented 

or not present. This evidence for high binding of the hydrophobic drugs to the central 

medulla helps explain the hair color and racial bias found in hair drug testing. (See also 

Abstract on page A-1 2.) 

K.S. Kalasinsky (Armed Forces Institute of Pathology), and D.C. Cameron (DHC Analysis) 

P

NSLS ADVISORY COMMITTEES 

1997-1998 

Users Executive Committee 

The Users' Executive Committee (UEC) provides for organized discussions among the user 

community, NSLS administration, and laboratory directorate. It aims to communicate current and 

future needs, concerns, trends within the user community to NSLS staff and management, and to 

disseminate to the users information about NSLS and BNL plans. Members were: 

Chairperson: Joel D. Brock, Cornell University 

Vice-Chairperson: John Parise, SUNY @ Stony Brook 

Past-Chairperson: Peter Stephens, SUNY @ Stony Brook 

Secretary: Elaine DiMasi, BNL-Physics 

General Members: Thomas Russell (U. of Massachusetts), Barbara lllman (U. of 

Wisconsin), Ian Robinson (U. of Illinois) 

Paul Stevens(Exxon Res. 8 Engr.) 

NSLS User Administrator: Eva Rothman, Ex-Officio 

Beamline Support/R%D Head: D. Peter Siddons, Ex-Officio 

Special lnterest Group Representatives 

Special lnterest groups in areas of common concern communicate with NSLS 

management through the UEC. Croup representatives were: 

Biological Scattering, Diffraction Malcolm Capel, BNL-Biology 

imaging Carl Zimba, NlST 

Industrial Users Sanjeeva N. Murthy, AlliedSignal, Inc. 

Infrared Users G. Lawrence Carr, BNL-NSLS 

Nuclear Physics Steven C. Whisnant, U. of So. Carolina 

Time Resolved Spectroscopy Jon Levin, U, of Tenn. 

Topography Michael Dudley, SUNY @ Stony Brook 

Students and Post Docs Elaine DiMasi, BNL-Physics 

UV Photoemission, Surface Science Peter Johnson, BNL-Physics 

XAFS Mark Chance, Albert Einstein Coll. of Med. 

X-ray Scattering, Crystallography Luz J. Martinez-Miranda, U. of Maryland 

General User Oversight Committee 

The CUOC resolves disputes between General Users, PRTs, and NSLS staff. Members were: 

Simon Bare, UP0 Mark Chance, Albert Einstein Coll. of Med. 

Dale Sayers, NCSU Peter Stephens, SUNY @ Stony Brook

Science Advisory Committee 

The Science Advisory Committee (SAC) evaluates the science pro- 

grams at the NSLS and makes recommendations to the Chairman. 

The SAC met in March of 1997 and its members were: 

Boris Batterman, CHESS, Cornell U. 

Martin Blume, Brookhaven National Laboratory 

Stephen Harrison, HHMI, Haward U. 

Franz Himpsel, U, of Wisconsin, Madison 

Jochen Schneider, HASYLAB, DESY 

Albert J. Sievers, Cornell U. 

Paul Sigler, HHMI, Yale U. 

Sunil Sinha, APS, Argonne National Laboratory 

General User Proposal Study Panels 

The Proposal Study Panels met in November 1996, March 1997, and July 1997 to review and rate 

General User research proposals for the FY 1997 cycles. PSP members are drawn from the scientific 

community and usually sewe a two year term. Members during FY 1997 were: 

UV Panel 

Daniel Fischer NIST 

David Hanson SUNY 

Boris Sinkovic NYU 

David Tanner U. of Florida 

X-Ray Imaging/Other Panel 

Chris Jacobsen SUNY 

Alastair MacDowell Lucent Tech./Bell Labs. 

Steve Sutton U. of Chicago 

X-Ray Biology 

Aneel Aggarwal Columbia 

Jens Birktoft Hoffmann-LaRoche 

Howard Einspahr Bristol-Myers Squibb 

James Hurley NIH 

Thomas Terwilliger LANL 

Gregory Van Duyne U. of Penn 

X-Ray Spectroscopy Panel 

Chuck Bouldin NIST 

Bruce Bunker U. of Notre Dame 

Lars Furenlid NSLS 

Steven Heald APS 

William Orme-Johnson MIT 

James Penner-Hahn U. of Michigan 

Linda Powers Utah State U. 

Dale Sayers U. of North Carolina 

X-Ray Scattering/Diffraction Panel 

Joel Brock Cornell U. 

Jerome Cohen NWU 

Simon Moss U. of Houston 

Sunil Sinha ANL 

Cullie Sparks ORNL 

Thomas Russell IBM 

Allocation Panel 

The Allocation Panel met in November 1996, March 1997, and July 1997 to 

allocate time on beamlines to each General User proposal for the FY 1997 

cycles. Allocation Panel members are drawn from the scientific community 

and usually sewe a two year term. Members during FY 1997 were: 

UV Members X-Ray Members 

Harold Ade NCSU Malcolm Capel BNL-Biology 

David Heskett U. of R.I. Mark Chance Albert Einstein 

Jan Hrbek BNL-Chemistry Alex Darovsky SUNY-Stony Brook 

Paul Stevens Exxon Lars Furenlid BNL-NSLS 

Elio Vescovo BNL-NSLS John Hill BNL-Physics 

James McBreen BNL-DAS 

Gavin Watson U. of Maryland

Assoc~~rli CHAIRMAN 

ES&H: 

Thonilinson 

H 

ES&H Cooru>: Gniiir 

01:1:1clin: Dickinson 

Exr. Rsv. COORD: 

Ackcrninnn. Aloi 

(Sechcck), (Weilnndics), 

(Zantopp) 

QUAI llr Ass~JRAN~:~~: 

(Klcin). (Wrigley) 

NSLS STAFF 

Ahlett. Rcrrnnn, Carr, 

Donq. Ilowd, Furenlid. 

(Gn;"r), S. Hullmt. 

Khalid, Montnnu, I'.irk. 

Shck-Stefm. So, 

(Thonilinton), Vescovo. 

Willi.trns, Yin, Zhons. 

Student: H.-J. Kim 

Swv I

CHAIRMAN: Hart** 

DEPUTY CHAIRMAN: Krinsky 

ELECTRIAL SYSTEMS: 

Keane 

ENGINEERING: Biscardi, 

Buda, Pietraski, 

HEAD: Keane (Acting) 

Dabrowski, Feng-Berman 

Langenbach, M~chta, 

Pearson, Ramamoorthy, 

Smith, Tang, Teng 

I I 

TECH SUPERVISION: 

SR. SUP.: Rasmussen 

PIS: Meier 

W: D'Alsace 

DIAGNOSTICS: Rambo 

ES&H INTERLOCKS: 

Gallagher 

ELECT. DESIDRFT: Neuls 

POWER SUPPLIES: 

Borrelli, Fulkerson, 

Garrison, McDonald, 

RE Ramirez, 

Rodriques, Vaughn 

Frisbie, Link, 

Nielson, Tallent 

INTERLOCKS: 

I Best, Hughes, Poshka 1 

DESIGN: 

CHECKER: L. Hulbert 

Bohenek, Rubino 

SPECIAL PROJECTS: 

Romano, l? Singh 

(Bessemen), 

(Gartma er), (Klammis), 

[pfhes{ (Lacy), 

o zev~k), (Yan~) 

NSLS STAFF 

Proposal Study Panels 

Allocation Panel 

General Users Oversight Committee (GUOC) 

MECHANICAL ENGINEERING: 4 Woodle I 

ENGINEERING: 

Beauman, Chou, Lynch, 

Mortazavi, Skaritka 

DESIGN/DRAFTING GROUP: 

MECH. LEADER: Pjerov 

CHECKER: Palo 

Almas , Gross,Guglielmino, 

Kim, ltaicu, Stelmach, 

VACUUM GROUP: Foerster 

TECH SUPERVISION: 

SR. SUPERVISOR: McKenna 

MECH: Scheuerer 

VACUUM: DeBoer 

MECHANICAL: 

(Pagano, NC), Bambina, 

Breck, Newburgh, 

Pop, Radulescu, 

Rosenberg, Santangelo 

VACUUM: 

Caruso, Cern ar, 

DeToll, Freudienberg, 

Lanni, Tardd 

OPERATIONS: 

Heese 

INJECTION RING: Blum 

RING: Gamer 

X-RAY RING: Klaf 

BEAMLINE LIAISON: %aty 

OPERATIONS: I. Rothman 

MAINTENANCE' 

COORDINATOR: [Kemp] 

CONTROL ROOM 

SUPERVISOR: Church 

OPERATORS: 

Jahnes, Santana, 

Weiner, Zeitler 

COORDINATORS: 

LEADMAN: Kemp 

Buckle , Chmiel, Jew, 

Kl {harr, Ratzke, 

~3Lrton 

ASSISTANT TO CHAIRMAN 

ADMINISTRATION: 

Terrano 

LEAD: J. DESMOND 

DiFilip o Koebel, 

Laster, bite-~e~ace SECRETARIAL SUPPORT: 

HEAD: McBrien 

D. Buckley, Ciufo, 

Loverro, Marshall, 

I Messana, Thompson, I 

- 

DATABASE DEVELOPMENT: 

I Hicks t 

I I 

HEAD: E. Rothman 

Feierabend, Pinkston, 

Rogers, Wright 

TECH TRAINEE: Carle 

Wrigley 

BUILDING MANAGER: 

Kelly 1 

CARPENTERS: 

(Gildersleeve) 

(signed) Michael Hart, Chairman 

October 1, 1997 

4CUSTODIAL 

STAFF: 

(Bounauito), (Davis) 

(McPherson), (Ormandy), 

(Williams) 

PRT PERSONNEL: 

(S. Bennett), (Mingino), 

(Sambasivan) 1

NSLS BEAMLINE GUIDE 

OCTOBER 1997 

This table lists the abbreviations appearing in the Beamline Guides. 

ARUPS 

CD 

C-T 

ERG 

EXAFS 

I R 

LEGS 

MCD 

MI 

NEXAFS 

NIM 

PGM 

SEXAFS 

SGM 

S-N 

SXES 

TG M 

TOK 

UPS 

WB 

WDI 

XPS 

XAS 

Angle-Resolved Ultraviolet Photoemission Spectroscopy 

Circular Dichroism 

Czerney-Turner 

Extended Range Grasshopper 

Extended X-Ray Absorption Fine Structure 

Infrared 

Laser Electron Gamma Source 

Magnetic CD 

Michelson lnterferometer 

Near Edge X-ray Absorption Fine Structure 

Normal Incidence Monochromator 

Plane Grating Monochromator 

Surface EXAFS 

Spherical Grating Monochromator 

Seya-Namioka 

Soft X-ray Emission Spectroscopy 

Toroidal Grating Monochromator 

Transverse Optical Krystron 

Ultraviolet Photoemission Spectroscopy 

White Beam 

Wavefront Dividing lnterferometer 

X-ray Photoemission Spectroscopy 

X-ray Absorption Spectroscopy

VUV BEAMLINE GUIDE 

Beam Research Mono. Affiliation Local Contact Spokesperson 

line Program 

SEXAFS, ARUPS, XPS 

(Conceptual) 

IR Microscopy, 

Spectroscopy 

Detector and system 

calibration; meas. of 

material optical const.; 

spectrometeric properties 

(Conceptual) 

Photoelectron spect.; ERG 

exp. system and detector 

calibrations 

Photoemission TC M 

spectroscopy to study 

electronic structure in 

solids, surfaces 

Soft x-ray and/VUV SCM 

photoemission 

spectroscopy and photo 

absorption 

8-500 A Exxon 

Exxon 

Carnegie Inst. Wash 

MI Albert Einstein 

DC/DC Smiths Astro Obs 

Bechtel Nevada 

Los Alamos Natl Lab 

B DeVries 

516-344-5501 

516-344-5206 

B DeVries 

516-344-5501 

516-344-5206 

R Lu 

516-344-5502 

202-686-2410 

L Miller 

516-344-5502 

516-344-3800 

A Burek 

516-344-2838 

516-344-5503 

J Chen 

908-730-2738 

J Chen 

908-730-2738 

M Chance 

718-430-4136/2894 

R Blake 

505-466-0566 

Los Alamos Natl Lab M Sagurton R Blake 

Sandia Natl Lab 516-344-5503 505-466-0566 

Bechtel Nevada 51 6-344-5708 

SFA, Inc 

Boston U S Hulbert K Smith 

No Carolina St U 516-344-5504 617-353-61 17 

BNL-NSLS 516-344-7570 

Rutgers U 

Naval Res Lab J Park Y ldzerda 

BNL-NSLS 516-344-7290 202-767-4481 

SRRC 516-344-4744


line Program 

Grazing incid. MI, WDI 

Reflectivity in UHV; 

transmission 8 normal 

incidence reflectivity 

Diagnostic instrument 

monitors beam parameters 

during operations and 

machine studies 

Spin polarized angle- TGM 

resolved ultraviolet 

photoemission 

Lithography WB 

XPS and XAS on surface TGM 

and in bulk, under 

vacuum and atm.P 

U7B Photoemission; 

SEXAFS 

U8A ARUPS 

NEXAFS 

U8B ARUPS 

NEXAFS 

TC M IBM 

U8C Zone plate monochr. ZONE PL. IBM 

evaluation; reflectivity 

measurements of thin 

films and multilayers 

U8D (Conceptual) 

Scanning soft x-ray 

microscopy 

BNL-NSLS 

BNL-NSLS 

BNL-NSLS 

BNL-Physics 

ANL 

U of Texas 

BNL-Physics 

BNL-Chemistry 

Dow Chem 

NlST 

U of Michigan 

Rutgers U 

Texas A8M U 

BNL-NSLS 

IBM 

G Williams 

516-344-3634 

516-344-7529 

R Nawrocky 

516-344-5505 

516-344-4449 

E Vescovo 

516-344-5505 

516-344-7399 

S Hulbert 

516-344-7570 

516-344-5506 

Q Dong 

516-344-5507 

516-344-5358 

Q Dong 

516-344-5507 

516-344-5358 

J Yarmoff 

516-344-5508 

G Williams 

516-344-3634 

516-344-7529 

R Nawrocky 

516-344-5505 

516-344-4449 

E Vescovo 

516-344-5505 

516-344-7399 

D Fischer 

51 6-344-5177 

S Hulbert 

516-344-5507 

516-344-7570 

R McFeely 

914-945-2068 

K Zhang R McFeely 

516-344-5508 914-945-2068 

M Banaszak-Holl 

313-763-2283 

R McFeely R McFeely 

516-344-5508 914-945-2068 

914-945-2068 

R McFeely R McFeely 

516-344-5508 914-945-2068 

914-945-2068


line Program 

(Planned) WHTE.LIGHT 

PSD measurements of 

UHV materials at room 

temperature 

Absorption.;CD;MCD; C-T 

flores/phosphorescence 

spectrocpy (incl. times- 

res. fl.) 

(Commissioning GU INFRARED 

{I9981 High Brightnes IR 

measurements on "bad 

metals" 

BNL-NSLS C Lanni 

516-344-7766 

516-344-4100 

BNL-NSLS 

BNL-Physics 

IR microspectroscopy INFRARED BNL-NSLS 

Northrop Grumman 

Gas phase photo- NIM 

ionization and 

spectroscopy 

Soft x-ray photoemission 

(SXPS); XAS; N EXAFS 

(Available) TG M 

IR and far-IR measurement 

time-resolved (pump/probe 

IR 8 far-IR spectroscopy 

High res VUV/soft x-ray SGM 

abs and electron spectr. 

(incl. spin-polarized 

photoemission) 

UV/VUV spectroscopy; WB 

hi resol. Angle resolved 

photoemission of solid 

surf.;pump-probe GU-'98 

BNL-DAS 

BNL-Biology 

BNL-NSLS 

Oak Ridge Natl Lab 

BNL-NSLS 

BNL-DAS 

U of Florida 

BNL-NSLS 

J Sutherland 

516-344-5509 

516-344-3406 

C Homes 

516-344-5510 

516-344-7579 

G Carr 

516-344-5510 

516-344-2237 

J Sutherland 

516-344-551 1 

516-344-3406 

S Hulbert 

516-344-7570 

S Hulbert 

516-344-5512 

516-344-7570 

G Carr 

516-344-5512 

516-344-2237 

BNL-NSLS S Hulbert 

516-344-5913 

516-344-7570 

BNL-NSLS 

BNL-Physics 

Boston U 

Brandeis U 

S Hulbert 

516-344-5513 

516-344-7570 

Interferometry WB Lucent Tech S Spector 

516-344-5513 

C Foerster 

516-344-4754 

J Sutherland 

516-344-5509 

516-344-3406 

G Carr 

516-344-5510 

516-344-2237 

G Williams 

516-344-5510 

516-344-7529 

B Klemm 

516-342-4001 

D Mullins 

423-574-2796 

D Tanner 

352-392-4718 

S Hulbert 

516-344-5913 

516-344-7570 

E Jensen 

617-736-2865 

0 Wood 

908-582-4457


line Program 

U14A VUV/soft x-ray spectro- PGM BNL-NSLS 

scopy Auger Photo- Rutgers U 

Electron Coincidence 

Spectroscopy (APECS) 

U14B Diagnostic Instrument: WB 

VUV Ring beam position 

monitoring 

BNL-NSLS 

U15 Soft x-ray spectroscopy TGM BNL-NSLS 

(solids and gases) SUNY@Buff 

SUNY@SB 

U16A (Unassigned) 

U16B Unassigned - NSLS is 

handling any GUS who 

need time here 

BNL-NSLS 

M Shek 

516-344-5514 

516-344-5930 

J Hastings 

516-344-5514 

516-344-3930 

A Wen 

516-344-5515 

516-632-7918 

S Hulbert 

516-344-5514 

516-344-7570 

R Bartynski 

908-445-4839 

J Hastings 

516-344-5514 

516-344-3930 

D Hanson 

516-632-7917 

Y Kao 

716-645-2576 

S Hulbert S Hulbert 

516-344-5516 516-344-5516 

516-344-7570 516-344-7570

Beam Research Energy Affiliation Local Contact Spokesperson 

line Program (keV) 

Soft x-ray imaging 10-80 A SUNY@SB 

No Carolina St U 

BNL-NSLS 

LBNL 

AN L 

Soft x-ray spectroscopy 

Surface scattering 

X-ray microtomo- 

graphy 

Short wavelength 

crystallography, 

diffration and scattering 

Diffractometry; x-ray 

spectroscopy; scattering; 

crystallography; small 

angle scattering 

X-ray spectroscopy; 

powder diffraction 

10-50 A BNL-Physics 

KFA - Juelich 

Fritz-Haber-lnst 

Boston U 

6.5-30, WB Exxon 

Exxon 


SUNY@Buff 

SUNY@SB 

Amoco Corp 

Alfred U 

3-31 SUNY@SB 

SUNY@Buff 

Amoco Corp 

Alfred U 

4.0-40 KEV SUNY@SB 

SUNY@Buff 

Amoco Corp 

Alfred U 

S Wirick J Kirz 

516-344-5601 516-632-8106 

516-632-8095 C Jacobsen 

516-632-8093 

516-344-4723 

P Johnson P Johnson 

516-344-5701 51 6-344-5701 

516-344-3705 516-344-3705 

S Bennett K Liang 

516-344-5602 516-344-5602 

516-344-4719 908-730-3032 

S Bennett J Dunsmuir 

516-344-5602 908-730-2548 

516-344-4719 

L Ribaud P Coppens 

516-344-5603 716-645-68OO,x2217 

716-645-6800x2218 

GWu 

516-344-5603 


516-344-5603 716-645-6800,~2217 

716-645-6800x2218 

GWU 

516-344-5603 


516-344-5603 716-645-6800,~2217 

716-645-6800x2218 

P Stephens 

516-632-8156 

516-344-3176/5634



Surface science 4-20 

Multiwavelength 4-30 KEV 

anomalous diffraction 

analysis of crystalline 

biological macromolecules 

(Conceptual) 

Diffraction meas. 7-20 KEV 

from biological 

macromolecules 

Laser Electron Gamma 80-400 MEV 

Source (LEGS); medium 

energy nuclear physics 

Diagnostic 

Time and space resolved 4-20 

dispersive x-ray 

spectroscopy 

X-ray scattering 2.4-21.0 

SUNY@Buff L Ribaud P Coppens 

SUNY@SB 516-344-5603 716-645-6800,~2217 

Amoco Corp 716-645-6800x2218 

Alfred U P Stephens 

516-632-8156 

516-344-317615634 

Howard Hughes C Ogata W Hendrickson 

516-344-5604 212-305-3456 

516-344-7435 

Howard Hughes C Ogata W Hendrickson 

516-344-5585 212-305-3456 

516-344-7435 

BN L-Physics C Thorn A Sandorfi 

Norfolk St U 516-344-5605 516-344-7951 

Ohio U 516-344-7798 

U of So Carolina 

SUNY@SB 

Syracuse U 

U of Virginia 

VA Polytech €t St U 

U of Paris 

U of Mainz 

Frascati Natl Lab 

U of Rome II 

NSLS 

NSLS 

M Shek D. Peter Siddons 

516-344-5930 516-344-2738 

M Shek D. Peter Siddons 

516-344-5930 516-344-2738


line Program (kev) 

X7A 

X7B 

X8A 

X8C 

X9A 

X9B 

Xl OA 

X1OB 

XlOC 

High resolution 

structural studies 

through powder 

diffraction 

Crystallography; 

wide angle scattering 

Calibration of mirrors 8 

dector systems; material 

optical constants; 

spectrometric properties 

5-45 KEV 

5-21 

0.26-5.9 

Diffraction from 5-20 KEV 

biological macromolecules 

and detector calibrations 

AXAF 

Time-resolved x-ray 3.4-1 8.6 

footprinting; 

Small angle scattering; 3.2-18.8 

EXAFS; multiple anomalous 

diffraction (MAD); 

protein x-ray diffraction 

Diffraction; small 6-15.2 KEV 

angle scattering; 

crystallography; 

scattering; SAXA; WAXS 

Scattering; 

crystallography 

PXD, Reflectivity 

EXAFS 

Air Products 8 Chem 

BN L-Physics 

Mobil 

Carnegie lnst of Was 

UOP 

U of Pennsylvania 

SUNY@SB 

Chevron 

UCA@Santa Barbara 

NlST 

Swedish Nat Res Coun 

BNL-Chemistry 


Smiths Astro Obs 




Smiths Astro Obs 

Albert Einstein 

Rockefeller U 

Sloan-Kettering lnst 

Albert Einstein 

NIH 

Exxon 

8,12 KEV Exxon 

4.0-24.0 Exxon 

D Cox 

516-344-5607 

516-344-381 8 

P Woodward 

516-344-5065 

J Hanson 

516-344-5707 

516-344-4381 

M Sagurton 

516-344-5608 

516-344-5708 

M Sagurton 

516-344-5608 

516-344-5708 

M Sullivan 

516-344-5609 

516-344-3800 

M Sullivan 

516-344-5609 

516-344-3800 

D Cox 

516-344-5607 

516-344-381 8 

P Woodward 

516-344-5065 

T Koetzle 

516-344-4384 

J Larese 

516-344-4349 

516-344-4438 

R Blake 

505-466-0566 

G ldzorek 

505-667-8848 

M Chance 

718-430-4136 

718-430-2894 

M Chance 

718-430-4136 

718-430-2894 

S Bennett E Sirota 

516-344-561 0 

51 6-344-471 9 

908-730-3407 

B Zhang E Sirota 

516-344-5710 908-730-3407 

516-344-3553 

M Sansone P Stevens 

516-344-3265 908-730-2584 

908-730-0100



XllA EXAFS 

Xll B EXAFS 

Xl2A Instrument development 

and x-ray physics 

Xl2B Time-resolved and static 6-15 

x-ray diffr. of macromol. 


Xl2C Macromolecular 8-13 

crystallography; multi- 

wavelength anomalous 

dispersion (MAD) 

4.5-35 Naval Res Lab K Pandya D Sayers 

Mobil 516-344-561 1 91 9-51 5-4453 

U of Connecticut 516-344-3165 


Hoechst Celanese 

BNL-DAS 

The DuPont Co 

U of Washington 

Rice U 

Ill lnst Tech (IIT) 

Naval Surf War Cntr 

Georgia lnst Tech 

U of Notre Dame 

Advanced Fuel 

NJ lnst of Tech 

1.7-8 Naval Res Lab K Pandya D Sayers 

U of Notre Dame 516-344-561 1 91 9-51 5-4453 

Mobil 516-344-3165 


The DuPont Co 

BNL-NSLS 

U of Connecticut 

Advanced Fuel 

Naval Surf War Cntr 

Hoechst Celanese 


U of Washington 

Rice U 

BNL-NSLS J Ablett 

516-344-2738 

516-344-5627 

P Siddons 

516-344-2738 

516-344-5627 

BNL-Biology R Sweet 

516-344-5642 

516-344-3401 

P Siddons 

516-344-2738 

R Sweet 

516-344-5642 

516-344-3401



R8D optics development; 

soft x-ray utilization 

Scattering crystallogr. 3.5-40 

spectroscopy phase ID and 

resid. strain meas. high 

temp x-ray diffraction 

(Planned) Manuf. res. WHITE 

for hard x-ray lithogrphy 

exposures for precision 

microfabrication 

X-ray standing waves 3-20, WB 

X-ray absorption 1.8-1 0 

spectroscopy of complex, 

reactive, very dilute 

systems 

Surface diffraction 4-12 

rapid access for sample 7.85 

characterization; powder 

characterizati0n;thin 

film characeterization 

Novel spectroscopy; 3-16 

diffraction 

X-ray scattering at high 20-100, WB 

pressure and temperature 

Medical research: 27-35 

Angiography;Bronchography 

computed tomography; 

radiotherapy 

BNL-NSLS 


Univ of Ill Urb Cham 

U of Tennessee 

U of Houston 

Sandia Natl Lab 

BNL-NSLS 

AN L 

BNL-NSLS 

Northwestern U 

Lucent Tech 

Lucent Tech 

U of Illinois 

Lucent Tech 

BNL-NSLS 

Lucent Tech 

U of Illinois 

BN L-NSLS 

SUNY@SB 

BNL-NSLS 

BNL-Medical 

SUNY@SB 


Stanford U 

E Johnson 

51 6-344-5613 

516-344-4603 

J Hastings 

516-344-3930 

J Bai 

516-344-5614 

516-344-2583 

E Johnson 

516-344-5614 

516-344-4603 

J Milne 

516-344-5910 

Z Zhong 

51 6-344-5615 

516-344-5617 

P Northrup 

516-344-3565 

516-344-3565 

W Lehnert 

516-344-5616 

516-344-3635 

W Lehnert 

516-344-5716 

516-344-3635 

W Lehnert 

516-344-5816 

516-344-3635 

Z Zhong 

516-344-5717 

516-344-5617 

N Gmur 

516-344-5617 

516-344-2490 

E Johnson 

51 6-344-561 3 

516-344-4603 

C Ice 

423-574-2744 

E Johnson 

516-344-5614 

516-344-4603 

P Siddons 

516-344-2738, 5627 

M Bedzyk 

630-252-7763 

P Citrin 

908-582-5275 

K Evans-Lutterodt 

908-582-2154 

K Evans-Lutterodt 

908-582-2154 

M Marcus 

908-582-2749 

J Hastings 

516-344-3930 

W Thomlinson 

516-344-3937



Hi P research; energy 10-100, WB 

dispersive diffraction 

from microscopic sample 

volumes 

Diffuse and surface 

scattering 

X-ray spectroscopy 

X-ray absorption 

spectroscopy: EXAFS 

and XANES 

Topography; liquid 

surface scattering 

X-ray Scattering and 

diffraction 

X2OB Scattering at fixed 17.4 

energy 

Naval Res Lab 

LLN L 

Carnegie lnst of Was 

U of Chicago 

U of Missouri 

U. of Maryland 

BNL-DAS 

U of Illinois 

Purdue U 

Penn St U 

UOP 

Chevron 

AlliedSignal 

BNL-NSLS 

Dow Chem 

PPG Industries 

General Electric 

BNL-DAS 

U of Michigan 

BNL-NSLS 

U of Kentucky 

UCA@Davis 

Rutgers U 

Johns Hopkins U 

Army Research Lab 

SUNY@SB 

NASA 

U of Wisconsin 

Northrop Grumman 

Dartmouth Coll 

M IT 

IBM 

IBM 

M IT 

S Ehrlich 

516-344-561 8 

516-344-7862 

J Schwanof 

516-344-5618 

516-344-5635 

S Khalid 

516-344-5718 

516-344-7496 

F Lu 

516-344-5619 

516-344-2338 

L Furenlid 

516-344-5699 

Z Huang 

516-344-5719 

312-702-7229 

J Jordan-Sweet 

516-344-5720 

914-945-3322 


516-344-5720 

914-945-3322 

H Mao 

202-686-4454 

E Skelton 

202-767-3014 

S Ehrlich 

516-344-7862 

P Siddons 

516-344-2738 

S Khalid 

516-344-7496 

L Furenlid 

516-344-5699 

M Dudley 

516-632-8500 

M Schlossman 

312-996-8787 

R Birgeneau 

617-253-4937 


914-945-3322 

516-344-5192 


516-344-5720 

914-945-3322 

R Birgeneau 

617-253-4937



X-ray scattering and 

diffraction with high 

flux by multilayer 

monochromator 

Inelastic x-ray 

scattering 

X-ray scattering of thin 

films, multilayers, cata- 

lytic materials, electro- 

chemical interfaces 

X-ray scattering and 

spectroscoppy of liquid 

surfaces; magnetic stud. 

under magnetic fields 

X-ray Scattering studies 

of magnetism; structure 

and phase behavior of 

metal surfaces 

EXAFS 

Topography; small- 

angle scattering 

EXAFS; scattering; 


4-1 1 

5-10 

10 NOM. 

5-10 

3-12 

IBM 

M IT 

BNL-NSLS 

BNL-Physics 

BNL-DAS 

U of Maryland 

BNL-Physics 

Harvard U 

AN L 

BNL-Physics 

AN L 

U of Maryland 

NlST 

NlST 

Naval Res Lab 


516-344-5720 

914-945-3322 

C Kao 

516-344-5721 

516-344-4494 

B Ocko 

516-344-5622 

516-344-4299 

B Ocko 

516-344-5622 

516-344-4299 

J Hill 

51 6-344-5622 

516-344-3736 

J Woicik 

516-344-5823 

Z Fu 

516-344-3156 

516-344-5059 

D Fischer 

516-344-5623 

516-344-5177 

Z Fu 

516-344-3156 

516-344-5059 

J Kirkland 

516-344-5723 

516-344-2258 


516-344-5720 

914-945-3322 

R Birgeneau 

617-253-4937 

C Kao 

516-344-5721 

516-344-4494 

D Gibbs 

516-344-4608 

D Gibbs 

516-344-4608 

D Gibbs 

516-344-4608 

J Woicik 

516-344-5823 

G Long 

301 -975-5975



Atomic, molecular, and 1.8-5.0 

optical physics with 

x-rays 

Photoemission and 6-1800 

reflectance spectroscopy 

X25 High intensity, high 3-30 BNL-NSLS 

brightness photon beam; 

high Q-resolution elastic 

scattering 

X-ray Microscopy; 4-20, WB 

structural biology; 

atomic and molecular 

physics 

Dev. and applic. of x-ray 4-30, WB 

microscopy techniques; 

Laue diffraction protein 


X27A NSLS R8D only; instrument 

development and x-ray 

physics 

X27B NSLS R&D only; Develop 

exposure techniques; 

matls. char.; and tool 

development for microfab. 

NIST B Karlin 

BNL-NSLS 516-344-7863 

Northwestern U 516-344-5624 

U of Rhode Island 

U of Tennessee 

Brooklyn Coll - CUNY 

U of Maryland 

Naval Res Lab J Rife 

516-344-5724 

202-767-4654 

J Kirkland 

516-344-2258 

L Berman 

516-344-5625 

516-344-5333 

Z Yin 

516-344-5625 

516-344-5525 

U of Chicago/CARS G Shea-McCarthy 

BNL-DAS 516-344-5626 

BNL-Biology 516-344-2229 

U of Georgia/SREL 

Cold Spring Harb Lab 

SUNY@SB 

BNL-Biology G Shea-McCarthy 

BNL-DAS 516-344-5726 

U of ChicagoKARS 516-344-2229 

U of Georgia/SREL 

Cold Spring Harb Lab 

SUNY@SB 

BNL-NSLS B Dowd 

516-344-5738 

516-344-7092 

BNL-NSLS E Johnson 

516-344-5627 

516-344-4603 

J Milne 

516-344-5910 

516-344-5910 

T Jach 

301 -975-2362 

M Kabler 

202-767-2223 

L Berman 

516-344-5625 

516-344-5333 

S Sutton 

630-252-0426 

S Sutton 

630-252-0426 

P Siddons 

516-344-2738 

E Johnson 

516-344-5627 

516-344-4603 

P Siddons 

516-344-2738 

516-344-5627


line Program (kev) 

X27C Simultaneious small €t AlliedSignal F Yeh B Hsiao 

1 wide angle x-ray BNL-Physics 516-344-5627 

scattering (SWAX) in real General Electric 516-632-7892 516-632-7884 

1 time Hoechst Celanese Z Wang B Chu 

I 

Montell Polyolefins 

NlST 

516-632-7928 51 6-632-792 8 

SUNY@SB 

I X28A Instrument development; 

BNL-NSLS P Stefan P Stefan 

photon-based diagnostics 

and detector development 

for the X-ray Ring 

516-344-5728 516-344-21 17 

X28B Photon-based diagnostics 



X28C Photon-based diagnostics 



X29A (Available) 

X29B (Available) 

X30 Diagnostic Instrument 

BNL-NSLS 

BNL-NSLS 

BNL-NSLS 

F 

P Stefan P Stefan 

516-344-21 17 516-344-21 17 

P Stefan P Stefan 

516-344-21 17 516-344-21 17

Beamline X27A: Recent developments in porous materials have demonstrated the potential 

to achieve ultra-light weightmetal structures at reduced cost using a solid-gas eutectic 

solidification process known as the Casar process. The process is capable of producing 

controlled porosity in metals by influencing the size and shape of pores as well as the pore 

distributions. The stereo pair at right is a 3-D volume section of an aluminum alloy sample 

rendered from x-ray microtomography data. (See also Abstract on page B-245.) 

R. Schulte, R. Meilunas, A. Tobin, J. Papazian, T. Donnellan (Northrup-Crumman), B.A. Dowd, 

D.P. Siddons (NSLS), and B. Andrews (BNL - Computing and Communications Division)

From the Managing Editor 

Four years ago, in the FY 1994 Activity Report, the NSLS implemented a 

ncw Web-based abstract submission system. After the author enters the 

information using their Web browser sobare, the system stores the abstracts 

in an Oracle database which then allows the NSLS to publish the abstracts in 

many formats. The abstracts are not only being published in the printed book 

now, but also on the World Wide Web in both HTML and PDF formats. 

The past years' Abstracts and Activity Reports can be found at the NSLS 

Home Page, www.nsls.bnl.gov, under "Science". 

For this 1997 edition of the Activity Report, almost 600 abstracts were 

received (Appendices A and B). This is 100 more than last year and indicates 

that the NSLS user community is more willing and able to use the system. At 

the time the abstract submission system was implemented, it was viewed as 

very experimental and cutting-edge because there were not many such systems 

in use. Today, however, the scene on the Internet is quite different. Web 

forms are much more common and browser software has become more 

standardized, so people are more comfortable using them. In addition, the 

NSLS abstract system has been fine-tuned and enhanced over the past couple 

of years, becoming easier to use for both the authors and NSLS Production 

Staff. 

This edition of the Activity Report also contains a higher than usual number 

of publication references (Appendix C). The reason is that many users 

submitted more extensive lists to the NSLS this year, with publication dates 

in some cases dating back to 1990. Production Staff had to check all previous 

editions of the Activity Report to identi+ any rcfercnces which had nevcr 

before been included. To complete the official record of publications which 

used synchrotron data taken at the NSLS, the previously unlisted references 

were added to this year's list. Appendix C therefore contains publication 

references dating from 1996-1997 as well as a fair number from previous 

years.

Beamline U1A 

ABSTRACTS 

VUV Beamlines 

Orientation and Order in Microcontact-Printed, Self-Assembled Monolayers of Alkanethiols 

on Gold Investigated with NEXAFS ........................................................... 

D. Fischer, A. Marti, and G. Hahner (ETH Zurich) 

NEXAFS Studies of Benzene on the Si(100)-21 Surface .......................................... 

M. J. Kong, A. V. Teplyakov and S. F. Bent (New York University) 

NEXAFS Studies of Diels-Alder Reactions of Butadienes with the Si(100)-21 Surface as a 

Dienophile ..................................................................................... 

A. Teplyakov, M. J. Kong, S. E. Bent (New York U.) 

Beamline U2B 

Construction of an Infrared Beamline Dedicated to the Study of Bio-Medical Problems ...... 

M. R. Chance, L. M. Miller, Q. He, M. Sullivan (AECOM) and G. Williams (NSLS) 

Synchrotron Infrared Absorption of Single Crystal Brucite to 20 GPa ........................... 

A. F. Goncharov, R. J. Hemley, and H. K. Mao (Carnegie Inst. of Washington) 

Synchrotron Infrared Absorption and Raman Spectroscopy in para-Hydrogen to >200 GPa. ..... 

A. F. Goncharov, R. J. Hemley, H. K. Mao, and J. F. Shu (Carnegie Inst. of Washington) 

High-pressure Synchrotron Infrared Spectroscopy of Ar(H2)z and CH4(H2)2 Compounds ........ 

A. F. Goncharov, M. Somayazulu, R. J. Hemley, H. K. Mao (Carnegie Inst. of Washington) 

Drug Distribution in Human Hair Determined by Infrared Microscopy .......................... 

K. S. Kalasinsky (Armed Forces Institute of Pathology), and D. G. Cameron (DHC Analysis) 

Beamline U4A 

Band Structure of n-type Wurtzite GaN Studied Using Angle Resolved Spectroscopy ......... 

S. S. Dhesi, C. B. Stagarescu, Y. C. Chao, J. Downes and K. E. Smith, (Boston U.) 

Surface Electronic Structure of n-type Thin Film Wurtzite GaN ................................ 

S. S. Dhesi, C. B. Stagarescu, Y. C. Chao, J. Downes and K. E. Smith (Boston U.) 

................................................. 

Resonant Photoemission on VOz and V203 

E. Goering, M. Schramme, M. Klemm, S. Horn (U. Augsburg), and 

M. L. denBoer (Hunter College, CUNY) 

Beamline U4B 

Element Specific Magnetic Hysteresis from XRMS. ........................................... 

V. Chakarian, J. W. Freeland, Y. U. Idzerda (Naval Research Lab), and N. Unterberry 

(SJAVS)

Hclicity-Dcpcndcnt Al~sollit,~ Ahsorption Cross-sections of Co and Ni. ........................... 

V. Clii~kilri~11, Y. U. Itlz(di~ (Naval Rcsearc11 Lill)). and C. T. C~I(YI (SRRC. Titiwi~~~) 

Q~iantitativc Evi~l~at,ioi~ of Milgnctic RIomcnt Dctcrlni~ii~tion by RICD .......................... 

V. Chil.karian, Y. U. Idzcrda (Naval Research Lal)), ant1 C. T. C11011 (SRRC. Tili~i111) 

Exploring Magnetic Roliglincss in CoFc Thin Films ............................................. 

J. W. Frccland, V. Cl~akarian, K. BIISSII~RIIII. and Y. U. I(l~crtlit (NRL). H. \I:cl~~tl(, 

(F.U.-Bcrlin), arid C.-C. Kilo (NSLS) 

Probing tlic Magnct,ic Hysteresis of an Intcrfilcc with X-ray Rcsonailt Alag~~otic Scilttwi~~g ...... 

J. W. Rccland, V. Cll;~ki~rii~n. K. B~~ssiiiai~n. and Y. U. Idzcrtla (NRL). H. R7cmd(~ 

(F.U.-Berlin), and C.-C. Kao (NSLS) 

Directly Idcnt,ifying tlic Ordcr of Layer Sn-itching in NiFc/Cu/Ch Trili~~~~s ..................... 

J. W. Rcclalld, V. Chakariiln, and Y. U. Itlzcrtli~ (NRT,), S. Dollc~ty and .J. G. Z~III (C:il~~~(\gi(> 

Mcllon U.), arid C.-C. Kao (NSLS) 

Layer Switcliirig in a Co/Cr/Co Trilily~r ........................................................ 

J. W. ficcli~nd, V. Cl~akarian. and Y. U. Itl~crtli~ (NRL). H. \Ti.~~dv (F.IJ.-I~(Y~~II). and 

C.-C. Kao (NSLS) 

Deterinination of Vertical Correlation of hlagnctic Domilins in a Ahdtililyc~ ..................... 

Y. U. Idzcrdi~., J. W. Freeland (Naval Rtwarcl~ Lal)). a d C.4. Tiao (NSLS) 

Separating Clicmical aid hIagnct,ic Rolighncss by X-rny Rt'so~lilnt Rli~glictic Sci~ttc,ring .......... 

Y. U. Idzcrda, V. Cl~ilkarian, J. RT. Frc~li~nd (Naval Rcscarrl~ La\)). aid C.-C. I

Soft X-Ray Resonant Magnetic Reflectivity Study of Thin Films ................................ 

L. Skve, F Bartolomb, J.M. Tonnerre, D. Raou (LCG-CNRS), V. Chakarian (NRL) and 


Temperature Dependence of the Fe L-edge Magnetic EXAFS ................................... 

H. Wende, J.W. Freeland, Y.U. Idzerda (NRL), L. Lemke, and K. Baberschke (Freie U.) 

Beamline U4IR 

Characterization of Bitumen-Polymer Mixtures by Infrared Microspectroscopy ............... 

J-L. Bantignies, G. Fuchs (ELF Atochem, France) 

Infrared Micro Spectroscopy by Using Synchrotron Radiation Application to Microstructural 

Hair Characterization .......................................................................... 

J-L. Bantignies, G. Fuchs, (ELF Atochem, France), D. Lutz, S. Marrull (Yves Rocher, France) 

The c-Axis Reponse of Y1-,Ca,Ba2Cus07-s Single Crystals Studied by Far-Infrared 

Ellipsometry ................................................................................... 

C. Bernhard, R. Henn, A. Wittlin, and M. Cardona (Ma-Planck-Institut fuer 

Festkoerperforschung) 

Infrared Microspectroscopy Studies of Electronic and Electro-Optical Materials ................. 

L. G. Casagrande (Northrop Grumman Corporation) 

Mapping the Chemical Composition of Subchondral Bone in Osteoarthritis Using Infrared 

Microspectroscopy ............................................................................. 

M. R. Chance, L. M. Miller, D. Hammerman, R. Stanley (AECOM), and 

C. Carlson (Bowman-Gray Sch. of Med) 

Anharmonicity of Low Frequency Vibrational Modes in Amino Acid Polymers .................. 

M. R. Chance, L. M. Miller, Q. He, and S. Schwartz (AECOM) 

Chemical Composition of Bone Osteons in Osteoporosis and Osteopetrosis In Situ .............. 

M. R. Chance, L. M. Miller (AECOM), R. Mendelsohn (Rutgers U.), and A. Boesky 

(Hosp. for Special Surgery) 

IR Microspectroscopy of Laser Drilled Graphite/BMI Structural Composite Laminates .......... 

D. Di Marzio, L. G. Casagrande, and J. Clarke (Northrop Grumman) 

IR Microspectroscopy of Plasma Sprayed Liquid Crystal Polymer Films ......................... 

D. Di Marzio, L. G. Casagrande, J. Clarke (Northrop Grumman Corporation), J. Brogan, 

S. Sampath, and H. Herman (SUNY) 

Identification of Organic Compounds in the ALH84001 Meteorite from Mars .................... 

G. J. Flynn (SUNY at Plattsburgh), L. P. Keller and M. A. Miller (MVA Inc.) 

Experimental Check of the Diffuse Scattering of Conduction Electrons by Adsorbates on 

Metallic Surfaces .............................................................................. 

M. Hein and A. Otto (U. of Duesseldorf, Germany), P. Dumas (LURE and 

LASIR-CNRS-France) and G. P. Williams (NSLS) 

Spatially Resolved Characterization of Coal Heterogeneity with Synchrotron Infrared 

Microspectroscopy ............................................................................ 

F. M. Hoffmann (SCI-MED), P. Dumas (LURE and LASIR-CNRS, France), G. P. Williams 

(NSLS) and J. Paul (Bilkent U., Turkey) 

NO2 Activation and Alkali Compound Formation ............................................. 

F. M. Hoffmann, (SCI-MED, New York), G. P. Williams (NSLS) and J. Paul (Bilkent University, 

Ankara, Turkey).

In, Sltu Synchrot,ron Far Infr~rcd Spectroscopy of tllc Elcctrocl~c~nical Interface ................. 

C. A. Mclcildrcs (ANL), G. A. Bow11x1kt.r (U. of A~icklir~~d. N~w Z('illit11d) 1111d 

J. M. Lcgcr (U. dc Poiticrs, France) 

Infrared Mi~t,('rii~l~ for St,~~rIying Biological Syste111s \\'it11 Iiifrarcd hIicr0~~~~ct1~o~c~~1)y 

............ 

L. Millcr (AECORI) and L. Carr (NSLS) 

Cl~ar;~ctcrix;~t,ion of Bone AIincral hlotlcl Conipi~ids Thro1ig11 Far-111frarcd Spc~rt~mscol)y ....... 

L. M. Millrr, M. R. Chance, Q. Hc (AECOhI). R. hIt~ndrlsolin (Rlitgc~s IT.). A. 13oc~sliy 

(Hosp. For Spccial Surgery). and V. Vairavwm~irtl~y (Shorc~l~i~~~~-\\':~(li~~g 

Riv~r HS) 

I~lt,crchaiii Hydrogen-Bonding Iiitcractioiis Bctn-ccn the Fila~nc~its of Actill ...................... 

L. M. Millcr (AECOM) and B. C11asa11 (Boston U.) 

Mctal-Ligand Strct,cliiilg Frcqiicncics in Hcnieprotcins T111.01igli Far-I~~fr;~l.cd S1)~rtroscopy ....... 

L. Millor (AECOM), T. Sage and P. C11;unpion (n'ortl~(~i~~t(~r~~ IT.) 

Infrarctl Microspcct,roscopy of Siiiall Dust Pi~rticlcs of Astrop11ysic:ll Origins .................... 

G. Quith, .J. Borg. L. cI1Hcndcro~irt. J. P. Bibring (Inst. tl'Astrol)liysicl~~(' Sp;~tiirl(~. 

Orsay, Francc), P. D~iinas (LURE ant1 LASIR-CNRS. Orsay. France). C:. L. Ch1.1. i111(1 

G. P. Williimls (NSLS) 

Vibrational Dyllil~llic~ of CGO oil No1)lc RI~tal Surfaces .......................................... 

P. R.11dolf ( U. Namnr, B(4gili1n). R. Ra~al (U. of Liv~rpool. EII~I~II~CI). P. DIIIII;IS (1,IJRTS i111d 

AS1R.-CNR.S-Frmct), and G. P. 'll'illiaiiis (NSLS) 

Isotopc Effects for the Low Frcq~icncy RIodcs of CO/C11(100) ................................... 

G. P. Williams,( NSLS) and C. J. Hirsclim~lgl (LBNL) 

Low Rcq~ic~icy Dynamics for hlixt~ircs of S and CO on Cu(100) ................................ 

G. P. Willimls (NSLS) and C. J. Hirscl111111gl (U. of \Visco~~si~i) 

Beamline U5UA 

Partial Spcct,ral Weights of Disorderrd Co-Ptl All OJS 

W. ,J. Kim, J. H. Park. W. G. Park. S.-J. 011 (Sco~il National U.). H. .J. Kim. and 

E. Vcscovo (NSLS) 

..: ......................................... 

Electronic St,ruct,~~rcs and hlagnctic Ordrring of Fc0.52A10.,1X Alloy Films ........................ 

Y. P. Lcc, K. W. Kim, Y. V. K~itlryavtsev (S~iil~iionn U.. I Half-Mctdlic F(won~ag~~ct .................................................... 

J.-H. Park, E. Vcscovo, H.-J. Kim (NSLS). C. Kwon. R. Ramesli. 

and T. Vcnkatcsan (U. of hhrylantl) 

Snrfacc Bo~lndary Mngilctiznl of Half-metallic Fcrron~agnct Lilo,-;S~(l,al\I~~O:( .................... 

J.-H. Park, E. Vcscovo, H.-J. Kim (NSLS), C. Kn-on. R. Rwniesli. 

and T. Vcnkat,csan (U. of Rlaryland) 

On Magnct,ic 111st~al~ilitics in FcNil-, Ally Spin-polarization hlcas~~rcnimts of tllc Va1(~11c(~ B;III(~S 

Structarc of Psc~idonlorpliic Layers ............................................................. 

F.O. Scliiimann, R.. Zliang. hI. Hocllstrasscr. R. F. IYillis (PSU). E. Vcwovo. i r1~1 

H.-J. Kim (NSLS) 

Spin R csolvcd Photoc~nissio~~ Study of hlagnctitc ............................................... 

E. Vcscovo, H.-J.I

Beamline U7A 

Characterization of Pure and Sulfided NiMo04 Catalysts using Synchrotron based X-ray 

Absorption Spectroscopy (XAS) and Temperature Programmed Reduction (TPR) ............ A-38 

S. Chaturvedi, J. A. Rodriguez (BNL) and J. L. Brito (IVIC) 

Reaction of Sz with ZnO and Cu/ZnO Surfaces: Photoemission and Molecular Orbital 

Studies ........................................................................................ A-39 

S. Chaturvedi, J. A. Rodriguez and J. Hrbek (BNL) 

Chemistry/Orientation of Lubricants on Hard Disk Magnetic Media Substrates Using Near 

Edge X-ray Absorption Fine Structure ......................................................... A-39 

B. M. DeKoven (Dow), D.A. Fischer (NIST), G E. Potter, T. Richardson, D. J. Perettie (Dow), 

S. Bhatia (IBM), T. A. Morgan, (Dow), and S. Hsu (NIST) 

C-N Bond Activation of Cycloheylamine on the Ni(100) Surface ................................ A-40 

A. M. Gabelnick, S. M. Kane, A. T. Capitano (U. of Michigan), D. A. Fischer (NIST), 

and J. L. Gland (U. of Michigan) 

Examination of Ordering in Self Assembled Monolayers and Adsorbed Protein Films with Near 

Edge X-ray Absorption Fine Structure ......................................................... A-40 

L. Gamble, D. Castner (U. of Washington), D. Fischer (NIST), P. Stayton, and 

K. Nelson (U. of Washington) 

Photoemission of Cleaved and "As-Grown" Surfaces of Pyrite .................................. A-41 

J. Guevremont (Temple U.), M. A. A. Schoonen (SUNY at Stony Brook), D. Strongin (Temple 

U.), and M. Strongin (BNL) 

Surfaces of Semifluorinated Block Copolymers Studied Using NEXAFS ......................... A-41 

E. J. Kramer, J. Genzer (UCSB), J. Wang, H. Korner, C. K. Ober (Cornell U.), B. M. DeKoven, 

R. A. Bubeck (Dow Chemical Co.), and D. A. Fischer (NIST) 

Hole State Density and Superconductivity in Ca-substituted Yttrium Barium Copper 

................................................................................ 

Oxide (Y-1:2:3) A-42 

A. R. Moodenbaugh (BNL) and D. A. Fischer (NIST) 

Direct Observation of the Complete Rehybridization of the Carbon Carbon Double Bond in 

Chemisorbed Propylene on Supported Silver Materials Using NEXAFS ......................... A-42 

J. T. Ranney, D. A. Fischer (NIST), D. H. Parker, R. G. Bowman (Dow Chemical), 

and J. L. Gland (U. of Michigan) 

Tribochemical Reactions of Nanometer Lubricant Films ................ 

Z. F. Yin, S. M. Hsu, D. A. Fischer, X. Zhang and J. Zhang (NIST) 

Beamline U7B 

Partial Densities of States in Cu-Pd Alloys ...................... 

S. L. Qiu, Y. Li and R. G. Jordan (Florida Atlantic U.) 

Beamline U8A 

Photon-Stimulated Desorption of O+ from Zirconium Oxide .......... 

W. C. Simpson and T. M. Orlando (PNNL-EMSL), W. K. Wang 

and J. A. Yarmoff (U. C. Riverside-Physics) 

Photoemission Studies of the Chemisorption of Chlorine on InAs(001) . . 

W. K. Wang, J. A. Yarmoff (U. of California, Riverside and LBNL), 

and W. C. Simpson (EMSL, PNNL)

Beamline U8B 

Chloroctlianc P11ysisorl)cd on Hydrogciiatctl Si(ll1): A Test Systcin for t11(~ Evi~lll;~tioi~ of 

Core-Lcvcl XPS Assigiment RII~CS ............................................................ A-45 

F. R.. McFerly (IBRI), I .................... A-45 

S. Lcc and M. AT. Baiiaszak-Holl (Brown U.), IV. H. Hling 

and F. R.. McFccly (IBRI) 

Si 2p Core-level Shifts at tlic Si(100)-Si02 Intcrfacc: An Expcrimciital Stlitly ................... A-4(; 

K. Z. Zliang, M M. Bmaszak-Holl (U. of AIicl~igan). .J. E. Bcildcr. S. Lw (Brow11 IT.), a ~tl 

F. R.. McFccly (IBRI) 

A New Model Silicon/Silicon Oxid(. 1iltc.rfacc Syi~tl~csizcd froin HloSiloOlr, ailtl Si (100)-2x1 .... A-4(; 

K. Z. Zliang, L. AL h4cciiwcnl)crg. RI. RI. Ba~laszak-Holl (IT. of RIicl~ifi;~i~). F. R. AIcFwly (II3RI) 

Soft X-ra.y Si 21, Core-lcvcl Spcctra of HXSiKOl2 Pl~ysisorl)(d 011 Si(ll1)-H: Additio~~al F:xp(~~.iil~o~~t ill 

Evidcilcc R.c?gartling t,lic Binding Energy Shift of the HSiO:( Fragi~lcnt .......................... 

K. Z. Zliang and R4. Rll. Bnnaszak Holl (U. of Rlicl~iga~~). F. R. RlrFwly (IDAI) 

Thc R.olc of Extjra.-Atomic Relaxation in Dctcmii~iiig Si 21) Bindi~ig E11crgy Shifts ilt 

Silicon/Silicon Oxitlc Iilt,crf;lccs ................................................................ 

K. Z. Zllang, J. N. Grcclcy, RI. 11. Bai1;lsz;lk-Holl (U. of RIicliigi~n). F. R. RIcFooly (IBRI) 

Beamline U9B 

Fll~orcscc~lcc of Paprr Filt.crs ................................................................. 

R.. Mantn.liff(: (Pall Corporation) and .J. Si~tllcrlaiid (BK1,-Biology) 

Pliotol~iilliilescci~cc Study of Simox Blirirtl Oxide ............................................... 

H. Nishikawa (TMU), J. H. St>i~this: (IBIU) and R.E. Stahll)l~sl~ (NRL) 

Use of Fh~orcsccncc Homot~ransfcr t,o RIoiiitor BOPIPY-iiiclittin Oligoi~ic~rizirtioi~ ................ 

S. Sca.rlat,a (SUNY at St,ony Brook) 

Time Rcsolvcd Fluorcscci~cc Polarizi~tion hlcaslircinciits for Eiitirc Eliiissioil Spectra wit 11 ;I 

Resistive-anods, Singlc-photon-coimtii~g Dctcctor: Tllc Flilorcsccncc 011111ilyzvr ................. 

J. C. S~it,l~rlnnd, L. A. Kelly, J. G. Trilnk. D. C. Rlontclcoi~c ;1nd I

Fluorescence Measurements of Indole Photoionization Products 

P. LeBreton (U. of Illinois at Chicago) 

................................. 

Circular Dichroism Evidence for Solution Linkage Flexibility in (1-3)-Linked a-D-Mannopyranoside 

Residues ....................................................................................... 

E. S. Stevens (SUNY at Binghamton) 

VUV Spectroscopy of Amide Chromophores .................................................... 

J. C. Sutherland, J. G. Trunk (BNL-Biology), and M. J. Kelley (DuPont Central Research) 

Photoionization Efficiency Spectrum and Ionization Energy of the Cyanomethyl Radical CH2CN 

and Products of the N(~S) + C2H3 Reaction ................................................... 

R. P. Thorn, Jr., P. S. Monks, L. J. Stief (NASAIGSFC), S.-C. Kuo, Z. Zhang, S. K. Ross and 

R. B. Klemm (BNL) 

Discharge Flow-Photoionization Mass Spectrometric Study of HOCl: Photoionization Efficiency 

Spectrum and Ionization Energy ............................................................... 

R. P. Thorn, Jr., L. J. Stief (NASAIGoddard), S.-C. Kuo, and R. B. Klemm(BNL) 

Radiative Recombination in Rare-Earth Doped Insulating Materials ............................ 

A. J. Wojtowicz and J. Glodo (Boston U.) 

Beamline U12IR 

Evidence for Coherent Emission from the VUV Ring in the Very Far Infrared ............... 

G.L. Carr (NSLS), R.P.S.M. Lobo (U. Florida & NSLS), J. LaVeigne, D. H. Reitze 

and D. B. Tanner (U. Of Florida) 

Design of the U12IR Beamline for Solid State Infrared Spectroscopy ............................ 

G. L. Carr, G. P. Williams and D. Lynch (NSLS) 

Initial Tests of the New Infrared Beamline U12IR .............................................. 

R. P. S. M. Lobo, J. LaVeigne, D. B. Tanner (U. of Florida), and G. L. Carr (NSLS) 

A Pulsed Synchronized Laser System for Time-Resolved Spectroscopy .......................... 

D. H. Reitze, J. LaVeigne, D. B. Tanner (U. of Florida), R. P. S .M Lobo (U. of Florida & 

NSLS), and G. L. Carr (NSLS) 

Beamline Ul3UA 

Large Value of the Electron-Phonon Coupling Parameter X = 1.15 and the Possibility of Surface 

Superconductivity at the Be(0001) Surface .................................................... A-58 

T. Balasubramanian, E. Jensen (Brandeis U.), X. Wu, and S.L. Hulbert (BNL) 

Beamline U14A 

Line Shape of the Ag NZ3VV Auger Transition Measured by Auger Photoelectron Coincidence 

Spectroscopy .................................................................................. A-58 

A. Danese, Q. Qian, R. A. Bartynski (Rutgers U.), and S. L. Hulbert (NSLS) 

Adsorption of NH3 on Ti02(110) Studied by Auger Photoelectron Coincidence Spectroscopy .... A-59 

W. K. Siu, R. A. Bartynski (Rutgers U.), A. Nangia, A. H. Weiss (U. Texas at Arlington), 

X. Wu, and S. L. Hulbert (NSLS)

Orientation and Order in Microcontact-Printed, Self-Assembled 

Monolayers of Alkanethiols on Gold Investigated with NEXAFS 

D. Fischer, A. Marti, and G. Hahner (ETH Zurich, Department of Materials) 

U1A 

The field of self-assembled monolayers (SAMs) has been a research area of increas- 

ing interest for more than a decade due to their ease of preparation and large number 

of potential applications. Particularly alkanethiols, mostly adsorbed on gold, are 

well characterized and known to establish well-ordered and highly oriented films. 

The recently developed technique of microcontact-printing (PCP) by Whitesides et 

al. allows SAMs to be laterally structured down to the (sub)micrometer range. In 

short, a PDMS stamp that is inked with the thiol solution is used to print the thiol 

onto the substrate surface. 

We have investigated such contact-printed (CP) layers of alkanethiols on gold with 

NEXAFS and compared them to layers prepared by the conventional immersion 

technique [I]. We studied the influence on order and orientation of the alkyl chains 

of both the chain length of the thiols and the concentration of the solution that was 

used for stamping and for immersion. 

Our study shows that the CP process, when performed with a sufficiently concen- 

trated solution of the thiol, can result in monolayers indistinguishable from those 

established by immersion into solution, independent of the thiol chain length. For 

lower concentrations, however, CP monolayers show a significant deviation from 

well-ordered films and have to be classified as mainly disordered. As with SAMs 

prepared from solution, shorter chains (dodecanethiol) lead to a lower degree of 

order compared to longer ones (hexadecanethiol) and hence a relatively higher per- 

centage of gauche conformations. NEXAFS is capable of detecting this difference of 

gauche defects, which is on the order of 30%. Since we do not observe any difference 

in our NEXAFS spectra for the different preparation methods for one chain length 

and sufficiently high concentrations, the upper limit of the difference in the density 

of defects in the resulting films can be estimated to be 30%. 

[I] D. Fischer, A. Marti and G. Hahner, J. Vac. Sci. Technol. A 15 (4), 2173, 

(1997) 

1 NEXAFS Studies of Benzene on the Si(100)-2x1 Surface 

M.J. Kong, A.V. Teplyakov and S.F. Bent (New York University) 

Interaction of benzene with various single crystalline surfaces has served as a 

reference point in the studies of a variety of processes. Here we present the Near 

Edge X-ray Absorption Fine Structure (NEXAFS) studies of benzene on Si(100)- 

2x1. This system is an excellent model for the interaction of hydrocarbons with 

silicon surfaces and for the formation of silicon-carbon interface, relevant for the 

manufacturing of electronic devices. Benzene has been studied on silicon surfaces 

relatively extensively; however, questions still remain about the detailed chemistry. 

Most importantly, it is still not understood if benzene reacts with the Si(100)- 

2x1 surface only at room temperature or if this reaction occurs at 100 K as well. 

Previous studies used thermal desorption spectrometry and HREELS to answer this 

question, but the obtained results were inconclusive. The use of NEXAFS allows 

one to determine if benzene is chemisorbed or physisorbed at cryogenic temperature 

by following its signature split p* transition, which is characteristic of a conjugated 

system. Furthermore, the nature of the product of the reaction of benzene with 

the Si(100)-2x1 surface at room temperature can be probed by using the same 

approach. Fig. 1 presents the spectrum of benzene taken at glancing and at normal 

incidence for submonolayer coverage adsorbed on the Si(100)-2x1 surface at 100 

K. The split p* transition is easily seen at glancing incidence. The average of the 

spectra taken at glancing and normal incidence of the photon beam is consistent 

with the multilayer spectra of benzene and with the literature results on benzene 

physisorbed on unreactive surfaces. The angle between the plane of the benzene 

molecule and Si(100)-2x1 surface was found to be 30, which is consistent with the 

strongly corrugated nature of the Si(100)-2x1 surface. Fig. 2 presents the spectra 

analogous to those described in Fig. 1, but taken at room temperature. These 

spectra are clearly different from those of the physisorbed benzene. The split p* 

transition, signature of conjugation, seems to be absent, whereas s*C-H, s*C-C, and 

s*C=C are clearly seen. All these results suggest that benzene physisorbs on the 

Si(100)-2x1 surface at 100 K without significant alteration of its electronic structure. 

At room temperature, however, it reacts with this surface chemically to form an 

intermediate without conjugated double bonds. One of the possible intermediates is 

shown in the inset for Fig. 2. Further studies are needed to support this structure. 

~(g.1. NWFS iD(100)-2x1 rtudlesaf at 100 benzene K 

n: 

285.6 

1 LatlOOK 

Flg.2. NEXAFS sludies of benzene 

ISI(~O(J)QX~ at mom temperature 

1000 L at Room Temperature 

U1A

? 

F 

3 

-NEXAFS Studies of Diels-Alder Reactions of Butadienes with the 

Si(100)-2x1 Surface as a Dienophile 

A. Teplyakov. hI. J. Kong. S.E. Bent (New York U.) 

U1A 

Over the last few decades. increasing use of semiconductor-based electronic devices 

has clirectecl serious attention towards the chemical properties of interfaces. 

specifically. towards the silicon-carbon interface. Directly related to the properties 

of this interface, is the sernicontlnctor chemistry of hydrocarbons at silicon surfaces. 

The interaction of simple hydrocarbons (ethylene, acetylene. benzene) has been 

stndied on silicon single crystal sl~rfaces in some detail; however, even for these 

simple hyclrocarbons. the reaction chemistry is still not completely untlerstootl. In 

the studies presented here. wc direct our attention to a Diels-Alder type reaction 

bct\vcen the 2.3- tlimethyl-1.3-butatliene and the silicon tli~ners of the Si(100)-2x1 

surface which was theoretically predicted hy R. I

Synchrotron Infrared Absorption of Single Crystal Brucite to 20 GPa I U2B 

A. F. Goncharov, R. J. Hemley, and H. K. Mao (Carnegie Inst. of Washington) 

The high-pressure behavior of brucite, Mg(OH)z, is of great interest because this 

compound may serve as an analog of complex hydrogen-bearing silicates of the 

Earth's crust and mantle. In this work we studied for the first time the infrared 

absorption spectra of brucite single crystals. Measurements were done at U2B NSLS 

beamline using FT-IR spectrometer and diamond anvil cells. Samples of several 

micrometers thickness were loaded into the pressure chamber with ruby pressure 

gauge and KBr or NaCl pressure transmitting medium. Transmission spectra were 

normalized to the transmission of the cell with the medium at the same pressure. 

The infrared spectrum of brucite in the mid-IR consists of 0-H fundamental and 

its combination modes with the low-frequency lattice phonons. The 0-H stretch- 

ing mode is only weakly active in the geometry used (direction of propagation is 

perpendicular to the basal plane of the crystals) because the transition moment 

direction is parallel to the wave vector of light. We observe that 0-H fundamentals 

broadens under pressure and at 4 GPa new bands appear at lower frequencies and 

gain intensity with pressure. These modes soften with pressure. The initial 0-H 

fundamental loses intensity gradually and at approximately 20 GPa becomes almost 

unobserved. On the pressure release the initial IR spectrum is restored at ambient 

pressure, but some hysteresis is observed and new bands are seen almost to ambient 

pressure. The observed phenomena are interpreted as due to the phase transition, 

which involves displacements of hydrogen atoms from their original axial sites as 

was also proposed in recent neutron diffraction an Raman studies [1,2]. 

T. S. Duffy et al., Am. Mineralogist, 80, 222 (1995) 

Catti et al., Phys. and Chem. of Minerals. 

Synchrotron Infrared Absorption and Raman Spectroscopy in para- 

Hydrogen to >200 GPa. I u 2 I ~ 

A. F. Goncharov, R. J. Hemley, H. K. Mao, and J. F. Shu 

We have studied solid Hz by infrared and Raman spectroscopy to pressures in ex- 

cess of 200 GPa and to 8 K. After cooling down to T

? 

w 

ti^ High-pressure Synchrotron Infrared Spectroscopy of Ar(H2)2 and 

I Drug Distribution in Human Hair Determined by Infrared hIicroscopy I U2B I 

CH4 (H2)2 Compounds 

U2B 

A. F. Goncharov. 11. Somayazulu. R. J. Hemley. H. K. hIao (Carnegie Inst. of 

\\*ashington) 

The infrared spectra of new hydrogen containing compound Ar(H2)z and 

CH.l(H2)a has been measured with synchrotron radiation to 220 GPa and 60 

GPa, respectively, to study the ordering phenomena and/or possible metallization/dissociation 

transitions. The infrared spectra of these compo~~nds consist of a 

nunher of IR-active ft~ntlarnentals and co~nbirlational rnocles with rot,ational cxcitations 

and lattice phonons. -411 these excitations persist to highest pressures achieved, 

manifesting the stability of inolecnlar strnctures mtler co~npression. Change of intensities 

of C-H stretching vibration and hydrogen vibron in CH is interpreted 

as clue to t~rn~s~lal chargr trnnsfcr between the CH., and Hz molecules above 30 GPa. 

No Drutlc-type absorption t,o 0.3 CV was found for Imth compot~ntls. 

K.S. Kalasinsky (Armed Forces Institute of Pathology), and D.G. Cameron (DHC 

Analysis) 

Localization of drug metabolites within human hair is important in determining 

the pharmacokinetics of drug incorporation in hair. This information is critical to 

validate drug testing data from hair. Previous work at the NSLS had shown the feasibility 

of this project for resolving the drug incorporation issue on the synchrotron 

infrared microscope with longitudinally rrlicrotomecl hair sections. Doped hairs 

compared to reference hairs shon-etl spectral differences with bands corresponding 

to tlw frequencirs of the drug of interest. However. patient hairs were obscurctl 

due to a contamination arriving form the sample prep process. Corrections mere 

n~acle to the preparation procctlure and subserpent work was performed at NSLS 

this year. Repeat work of the doped hairs versus reference hairs were performed for 

cocainc ant1 heroin drugs of abusc. Thr results showrcl the drug to be in the central 

rnctlulla of the tlopctl hair. X~lalysis of thr patient hairs from cocaine and heroin 

abusers sllo~vctl the same results. The thlg was concrntratecl in the medulla of the 

hair. \Then the patient hatl nou-mctl~~llatctl hair thr drug mas not present. Below 

is a. topical grapll of a hair from tlw synchrot,ron infrar~tl microscope. 11lappct1 for 

the prirlrary frequency hand for cocairic in n ihlg ab~~srrs hair. The graph sho\vs 

the drug to he in it highcst concc~ntration in t,he rrnt,ral port,ion of the hair and the 

lack of tlrng absorpt,ion in parts of thc ccwtral portion of the llnir correlate to arras 

where the metlulla ~vas fragulcntctl or not prcwnt. This rvitlenct, for high binding 

of t,hc hytlrophobic ilrugs to the ccr~trnl ~ nt~l~~lla hrlps rxplain thr hair color ant1 

racial bias fount1 in hair tlrug tcsting. Thv 1iglltt.r hairs with Irss rnctlulla rct,ain 

lrss hytlropllolic tlrug per tlosc. 'I'llc thrker I~airs typically havt, grrntrr mctl~~lla 

content mil llcrlcc Ilcavicr loatlirlg of tlrl~g per tlosc. E'rc,vio~~s st11t1ic.s intlicat,cd that 

~nrlanin was thr primary factor for tlrt~g rctcntiorl tn~t this c~vitlcr~ct~ strongly points 

to atltIit,ional drug lintling to variol~s hair colnpor~cr~ts. This tlr~~g clistril)~~tiorl i~tltl 

mrchanisrn of incorporation is rlcccssarl- for tlctcrrrlirling thc bintling ant1 trar~sport 

of thr tlr~~g to t.hc hair. This information is rcquirctl hforc hair testing cm bc 11sci1 

as a stand nlonc, piccc of cvitlrncc in court cases. Further stldics arc, ~~ccdctl for the 

varior~s tlr~~gs and hair typ~s. 

Figure 1. Image of cocaine distribution in hair shaft.

Band Structure of n-type Wurtzite GaN Studied Using Angle Re- 

solved Spectroscopy I u4A I 

S.S. Dhesi, C.B. Stagarescu, Y.C. Chao, J. Downes and K.E. Smith, (Boston 

University) 

The valence band electronic structure of wurtzite GaN has been determined us- 

ing angle resolved photoemission spectroscopy. Clean, ordered surfaces were pre- 

pared by reapeated cycles of nitrogen-ions bombardment and annealing in ultra- 

high vacuum. Spectra were recorded along the main symmetry directions of the 

bulk Brillouin zone. The band dispersion along these high symmetry directions was 

determined, as were relative critical-point binding energies. 

When compared to existing band-structure calculations, our data indicates that 

local density approximation band-structure calculations using partial-core correc- 

tions for the Ga 3d states predict the relative binding energies of the main critical 

points with a high degree of accuracy. 

A similar study, investigating the bulk and surface electronic structure of the 

p-type GaN is undergoing. 

Wurtzite GaN Band Structure 

r K M r A 

Figure 1. 

Calculation fkm Rnbio ef al, 

Phys. Rev. B48 11810 (1993) 

Surface Electronic Structure of n-type Thin Film Wurtzite GaN I U4A 

S.S. Dhesi, C.B. Stagarescu, Y.C. Chao, J. Downes and K.E. Smith (Boston Uni- 

versity) 

Gallium nitride and related nitride wide band gap semiconductors are an im- 

portant class of electronic materials due to potential use in optoelectronic devices 

operating in the blue to ultraviolet spectral range. Consequently, a thorough under- 

standing of the electronic structure of such nitrides is of fundamental importance. 

At beamline U4A, we have investigated the nature of the substantial band-bending 

( Fermi level pinning ) at the surface of thin film wurtzite GaN by the use of 

photoemission spectroscopy. Our angle resolved photoemission spectra taken from 

the in-situ cleaned surface of wurtzite GaN show clearly a non-dispersive emission 

feature localized near the valence band maximum, in the bulk band gap. Further 

measurements proved that the associated state does not show any dispersion along 

the the k, direction and is destroyed by absorption of oxygen or activated hydrogen, 

or by ion bombardment of the surface. All this, together with symmetry related 

arguments and measurements, allowed us to identify this feature with a surface 

state with sp, character, consistent with a dangling bond state. A similar study is 

presently pursued for the surface of the p-type thin film wurtzite GaN.

? 1 Resonant Photoemission on VOn and VzO. 

w 

,P 

I U ~ A 

E. Goering, N. Schramme, M. Klemm, S. Horn (U. Augsburg), M. L. denBoer 

(Hunter College CUNY) 

V203, a metallic paramagnet at high temperature and an insulating antiferromagnet 

below TA~I = 170 K, undergoes a structural transformation from the high 

temperature trigonal phase into a monoclinic phase, accomplished by a decrease in 

the c/a ratio (axes referred to the trigonal phase) and a tilt, by 1.9' with respect 

to the high temperature phase c-axis, of two of the three V pairs which occupy 

the octahedral sites. Whether the structural transition drives the electronic one, 

or vice-versa, is not known, but potentially very important to understanding the 

mechanism of this metal-insulator t,ransition (RIIT). In this context, it is noteworthy 

that doping V ~OQ with Cr or Al can also cause a metal-insulator transition, 

but one which does not change the lattice symmetry. 

Recent experiments cast some doubt on the importance of the trigonal to monoclinic 

distortion for the MIT. 0 K edge NEXAFS measurements on pure and Cr 

doped V203 single crystals in the metallic and insulating phases show the local 

electronic struct,ure of the Cr doped trigonal insulating phase and the low temperature 

monoclinic phase are the same, while EXAFS measurements show a monoclinic 

tlistortion on a microscopic scale in the room tenlperature metallic phase of pure 

V20:3 although the average structure is trigonal. te here are two possible interpretations: 

(i) The rnonoclinic distortion is irrelevant to the RIIT in pure V203, since 

the trigorial Cr tloped insulating phase shows the same local electronic structure, 

or (ii) a monoclinic distortion is also present in the Cr doped insulating phase. 

To decide between these possibilities wc have measured the V K edge x-ray absorptiori 

spectra of V~OQ single crystals, both pure and doped with A1 (rather than 

Cr, to avoid interference with the V edge). On these single crystals. we have rneasurect 

in fluorescence yield; this may introduce distortions due to self-absorption, 

which we have correctrd by measl~ring spectra at several sarnple geometries antl 

comparing to an explicit calcnlation.1Ve show in Fig. 1 the EXAFS spectra of a 

Vz03 as rneasuretl at several exit angles. The apparent amplitude differences caused 

by self-absorption are removed by the correct~on procedure. 

Although analysis of the extended fine structure is not yet complete, the spectra 

depend very clearly on the polarization between the incident beam and the single 

crystal samples. An example is shown in Fig. 2, in which the extended fine structure. 

transformed into R space, is shown for the incident polarization parallel and 

perpendicular to the sample c axis. 

Figure 2. Amplitude of representative 

Fignre 1. Photoemission spectra of regions of photoemission spectru~n of 

\*303 at various photon energies. 1-203 as function of photon energy. 

I 

I Element Specific Rkignetic Hysteresis from XRILIS. I U4B I 

V. Chakarian, J.W. Freeland, Y.U. Idzerda (Naval Research Lab), and N. Unter- 

berry (SJAVS) 

Element-specific magnetic hysteresis measurements performed in absorption are 

an established method for disecting the complex total moment hysteresis curves 

into their individual components to help understand the interplay between magnetic 

layers in a magnetic multilayer. Magnetic hysteresis curves performed in reflectivity 

would allow for a depth selectivity (by changing the incidence angle) not available 

in absorption. Shown in Fig. 1 is the dependence of the reflected specular intensity 

at resonance with the Co Lj edge as a function of applied magnetic field for various 

incidence angles for a single crystal Co/Cr/Co multilayer (grown on GaAs(100) 

substrate with an Fe seed layer (4 A) to promote the bcc Co phase). At first glance. 

the reflectivity curves seem completely unrelated to each other antl to the traditional 

magnetometry loop (shown in Fig. 2). These different reflectivity loops (normalized 

to unity and offset for clarity) are generated by the interference of scattering from 

the four Co interfaces in the trilaver. Changing the incidence angle (antl also the 

magnetic orientation) changes these interference conditions. generating the observcd 

variations in these reflectivity loops. However, these radically different hysteresis 

curves are related, each displays 2 plateau regions during the field cycle. If the 

loops are rescaled at these two points, then all the "reflectivity hysteresis" curves 

look sirnilar (see Fig. 2) antl have a qualitative agreement with the magnetornetry 

loop. The remaining differences are due to the failure of achieving complete anti- 

alignment of the two films in the plateau region. 

1 .(l 

(1.5 

- X 

.- 

fl 

5 0.0 

& 

e - 

-03 

-1.0 

- \Ingnctometrv 

-1m -50 0 50 100 

Magnetic Field (Oe) 

Figure 1. Normalized reflectivity curves Figure 2. Same reflectivity curves 

at the Co LQ edge at various angles (off- rescaled at two points and compared to 

set for clarity). a magnetometry loop.

? 

0 7 

I Helicity-Dependent Absolute Absorption Cross-sections of Co and Ni. I U4B I 

V.Chakarian, Y.U. Idzerda (Naval Research Lab), and C.T. Chen (SRRC, Taiwan). 

The extraction of reliable quantitative results from measured X-ray absorption 

spectra often requires the determination of absolute photoabsorption cross sections. 

Here, we report on the measured helicity dependent absolute cross sections for hcp 

Co and fcc Ni measured at their L2,3 edges for films deposited in situ at 10-lo Torr 

pressure from e-beam evaporators onto a parylene substrate, (CsH*),, held at room 

temperature. For these transmission measurements, the attenuation of the soft X- 

ray flux was determined by measuring the incident flux, Io, via the photocurrent 

drain on a highly transmitting Au grid, and measuring the transmitted flux with a 

Si photodiode. The structural phase of these materials was determined by k-edge 

EXAFS measurements. The total photoabsorption cross section can be obtained 

by using p ~ = ~ (p+ t + p- + p0)/3, where p+ is the photoabsorption cross section 

for positive helicity light, p- for negative helicity light, and po = (p+ + p-)/2 for 

linear polarized light. The data have been corrected for incidence angle, incomplete 

remnance, and degree of polarization of the beam. The spectra for Co and Ni 

(shown below) were scaled to calculated cross sections [I] in the pre- and post-edge 

regions. 

[l] J.J. Yeh and I. Lindau, Atomic Data and Nuclear Data Tables 32,l (1985). 

Photon Energy (eV) Photon Energy (eV) 

Figure 1. Measured helicity dependent photoabsorption cross section for LEFT: 

hcp Co and RIGHT: fcc Ni. 

I Quantitative Evaluation of Magnetic Moment Determination by MCD I U4B I 

V. Chakarian, Y.U. Idzerda (Naval Research Lab), and C.T. Chen (SRRC, Taiwan) 

Using the experimentally determined absolute cross sections, a realistic mean- 

escape-depth ([) for secondary electrons of 10 A, and a film thickness of 30 A, we can 

calculate the expected XAS and MCD spectra at various incidence angles (see Fig. 

1) to determine the severity of saturation/self-absorption effects in MCD moment 

extraction. The calculated XAS and MCD spectral shapes remain nearly unchanged 

for incidence angles

Exploring Magnetic Roughness in CoFe Thin Films 

U4B 

J.W. Freeland, V. Chakarian, K. Bussmann, and Y.U. Idzerda (NRL), H. Wende 

(F.U.-Berlin), C.-C. Kao (NSLS) 

The influence of roughness on the properties of thin film magnetic structures is a 

question of current interest to many facets of the magnetism community. Current 

results have shown that direct measurements of magnetic roughness as compared 

to measurements of the chemical roughness indicate that these interfaces are com- 

positionaly rough, but magnetically smooth1-? Since the magneto-transport of 

these structures is strongly affected by interfacial scattering and in particular from 

magnetic disorder at the interface. chemical roughness may not be the appropriate 

parameter for correlation with the degradation of the magnetic properties. However, 

to probe information about a magnetic interface one needs a significant magnetic 

scattering signal. One way of providing this is through the resonant enhancement 

of the magnetic and chemical scattering when an incident circular polarized pho- 

ton is tuned to an absorption edge, known as x-ray resonant magnetic scattering 

(XRhIS). To better understand the variation of magnetic vs. chemical interfaces we 

have nndertaken a study of thin CoFe films where an increasing chemical roughness 

was induced through the growth process. In particular we have studied the be- 

havior of both in plane and perpendicular roughness via helicity dependent sample 

rocking curves (i.e. where the detector angle was kept fixed and the sample angle 

was varied) meawretl at the Co Lg edge (see Fig. 1). The extracted rms roughriess 

values for the chemical (It + I-) vs. magnetic (I' - I-) interfaces clearly show 

the magrietic interface is typically smoother (20-30% smoother) than the clrenlical 

interface (see Fig. 2). Like the rms roughness, the lateral correlation lengths also 

are larger for thr magnetic iutcrface (not shown hrrr). 

I J.F. XIacKay et. al. Phys. Rev. Lett. 77. 3925 (1996). 

2 Y.U. Itlzerda, et. al., Synchrotron Radiatiori News 10, No. 3, 6 (1997). 

3 .J.\V. Freeland et. al. Submitted to -1. Appl. Phys. 

/ 1 

Figme 1. Sample rocking curve measurecl 

at the Co Lg (778 el') for chem- 

5 10 1.5 20 2.5 

.WM Roughness ( il 

30 

ical ((I- + I-)/2) and 

I-) contributions. 

(1- - Figure 2. Roughness parameters derived 

from the diffuse scattering data. 

Probing the Magnetic Hysteresis of an Interface with X-ray Resonant 

Magnetic Scattering 

U4B 

J.W. Freeland, V. Chakarian, K. Bussmann, and Y.U. Idzerda (NRL), H. N7ende 

(F.U.-Berlin), C.-C. Kao (NSLS) 

Interfacial properties play an important role in the behavior of magnetic thin film 

structures. EfTects such as Giant Magneto-Resistance (GMR) and and exchange 

bias are strongly influenced by the prescence of "loose" spins at the interface (i.e. 

interfacial spins behaving differently than those in the bulk). One way to probe 

the behavior of interfacial spins is through the magnetic diffuse intensity1. The 

reflected intensity as a function of applied field can be utilized as a measure of 

the magnetic hysteresis since the magnetic portion of the scattering tracks with 

the magnetic moment of the sample. Since the fieltl dependence specular peak 

intensity gives a measure of the bulk magnetic hysteresis, we can use the diffuse 

signal, which only comes from the interfaces, to measure the interfacial magnetic 

hysteresis. In Fig. 1 the clear difference in the coercive and saturation fields of spins 

at the interface indicates the different nature of the bulk vs. interfacial magnetic 

environment. This was confirmed by measuring at not only several different points 

in the tliffuse, but also in the specular arld cliffuse at different tletector angles. 

Combining this measurerner~t with magnetic roughness rneasurrnerlts we can gain 

a much more complete picture of thc behavior of the interfacial spins. It is worth 

noting that sample indicating the largest difference between specular and diffuse 

coercive fieltl is also the one cxhibiting a roughening of the magnetic interface. 

[I] J.\\'. Freelnntl et. al. Suhmittctl to d. Appl. Phvs. 

-80 -60 -40 -20 0 20 40 60 80 

Magnetic Field (Oe) 

Figre 1. Interface and bulk magnetic hysteresis measured by XRlIS.

? 

-3 

Directly Identifying the Order of Layer Switching in NiFe/Cu/Co Trilayers 

I u4B I 

J.W. Freeland, V. Chakarian, and Y.U. Idzerda (NRL), S. Doherty and J.G. Zhu 

(Carnegie Mellon Univ.), C.-C. Kao (NSLS) 

In order to better understand the dynamics of layer switching, we present a study 

demonstrating how soft x-ray resonant magnetic scattering (XRMS) can be used 

to directly probe the layer switching in magnetic multilayersl. The behavior of 

magnetic layer switching critically controls spin-dependent electron transport in 

heteromagnetic systems. The determination of layer switching is accomplished by 

monitoring changes in the angular dependence of the magnetic contributions to the 

reflectivity at the L3 absorption edge as a function of applied field. The magnetic 

scattering asymmetry as a function of angle at the Fe L3 and Co L3 edges can be 

compared to directly determine not only the order of the layer switching, but to also 

extract information about the degree of anti-alignment of the layers. Comparison 

of the measured asymmetry of the aligned and anti-aligned states clearly shows 

that the NiFe layer is the first to switch and that the Co layer is never completely 

anti-aligned to the NiFe layer. The lack of complete anti-alignment is an indication 

of coupling between the layers probably due to dipolar magnetic coupling and/or 

film micromorphology. This demonstrates the power of XRMS as a probe of layer 

switching in magnetic heterostructures. 

[I] J.W. Freeland et. al. Appl. Phys. Lett. 71, 276 (1997). 

5 10 15 20 25 30 

8 [ degree I 

Figure 1. Top panel - Angular dependence of the asymmetry ratio, R, at the Fe 

and Co L3 edges for the aligned moment case. Bottom panel - Angular dependence 

of the asymmetry ratio at the Fe and Co L3 edges for the anti-aligned moment 

case. The sign change in the Fe asymmetry is clear demonstration of the NiFe layer 

switching first. 

I Layer Switching in a CojCrlCo Trilayer I U ~B I 

J.W. Freeland, V. Chakarian, and Y.U. Idzerda (NRL), H. Wende (F.U.-Berlin), 


Many conditions can effect the switching properties of multilayers, but since stan- 

dard magnetometry techniques, which measure only the total magnetic response, 

can only infer the order of the layer switching indirectly, there is need for a direct 

probe. The determination of layer switching is accomplished by monitoring changes 

in the angular dependence of the magnetic contributions to the reflectivity at the 

L3 absorption edge as a function of applied field1. A comparison of the asymmetry 

ratio R (=(I+ - I-)/(I+ + I-)) for the aligned and near anti-aligned states (see 

Fig. 1) illustrates the differences caused by the formation of an anti-aligned state. 

To determine which layer has switched first we examine the behavior at grazing 

incidence (i.e. small 8). Since the photon mean free path is small at the strongly 

absorbing L3 edge, at the low angles the measurement is predominately sensitive 

to the top layer. The sign change in the asymmetry ratio at low angles is an indi- 

cator of the magnetic orientation reversal of the top layer (see Fig. 1). Additional 

confirmation that the top layer switches first was made from the element specific 

hysteresis measured in reflectivity. By comparing the Co hysteresis with that of the 

7 A Fe seed layer which is ferromagnetically coupled to the bottom Co layer, we 

can confirm that the bottom layer is the last to switch. These conclusions are in 

agreement with a comparison made between the measured data and simulations for 

the different magnetic layer orientation combinations (aligned, top layer flip, and 

bottom layer flip). This comparison, not shown due to space limitations, shows that 

the data can only be reproduced if the top layer is the first to flip. 

[I] J.W. Freeland et. a1 Appl. Phys. Lett. 71, 276 (1997). 

5 10 15 20 25 

Incident Angle [degreel 

5 10 15 20 25 

Incident Angle [degreel 

Figure 1. Helicity dependent specular re- Figure 2. Angular dependence of the 

flectivity at the Co L3 edge as a function asymmetry ratio at the Co L3 edge for 

of incident angle. the aligned and anti-aligned states.

Determination of Vertical Correlation of klagnetic Domains in a Mul- 

Y.U. Idzerda, J.W. Freeland (Naval Research Lab), and C.-C. Kao (NSLS). 

I u4~ I 

Reflectivity measurements are a sensitive measure of the magnetic orientation of 

a magnetic film. For multilayer structures, the reflected specular intensity becomes 

dependent on the relative orientation of each of the magnetic films. Shown in the 

top of Fig. 1 is the magnetometry curve for a single crystal Co/Cr/Co trilayer 

grown epitaxially on GaAs(001) taken along its easy axis of magnetization. It is 

clear from the magnetometry curve that coupling through the Cr interlayer is giving 

rise to a state where the moments of the two Co layers are nearly anti-aligned at 

low fields. However, this state will not be in a perfectly anti-aligned clue to effects 

such as diploar coupling cansed by roughness. which mill reduce the degree of anti- 

alignment. In order to determine a complete description of the relative orientation 

of the two Co films the reflected specular intensity is measured as a function of 

applied field at varions incidence angles. From this functional dependence, we can 

statistically quantify the degree of correlation between the magnetic domains in the 

magnetic films. This vertical correlation must be generated by coupling through 

the interlayer. 

'J 0 5 

i. 

- Domain Correlation 

fullv correlated 

6 -1 1- fully anti-correlated 

50 10.1 

2 -loo Magnetic -3 Field (Oe) 

Separating Chemical and Magnetic Roughness by X-ray Resonant 

Magnetic Scattering. 

A central issue in magnetic thin film research is the correspondence of chemical 

roughness, the variation of atomic type near an interface, and magnetic roughness, 

the variation of atomic spin (both magnitude and direction) near an interface. One 

method which holds promise of selectively characterizing magnetic and chemical 

roughness is X-ray Resonant hlagnetic Scattering (XRhIS). By measuring the specularly 

reflected intensity of a CP soft x-ray from a magnetic film or multilayer as 

a function of energy, angle, and magnetic orientation, both chemical and magnetic 

thickness and roughness information can be extracted from the interface, analogons 

to the hard x-ray 8-28 scattering. As a demonstration, we have plotted below the 

asymmetry (difference between scattering using left or right CP soft x-rays normalized 

by their snm) as a function of photon energy antl incidence angle near the L3 

edge of Co for a 37 A Co film. For comparison, plotted to either side is the calculated 

asymmetry plot for a 37 A Co film assuming either no magnetic roughness (LEFT) 

or assnming a magnetic roughness equal to the experimentally determined chemical 

ronghness (5 A- RIGHT). It is clear from the comparison that the no roughness 

spectra agrees with the data better than the 5 A rough calcl~lation, suggesting that 

the Co film is magnetically smooth, but chemically rough. 

Below are shown the nornlalizecl helicity-tlepentlent asymmetry (difference of the 

two hclicitv tle~cntlent s~ectra normalized bv the sl~m) for 37 :i Co film as a function 

of incitlen& arigle antl photon energy. 

Cnlculnte~Reflectivity Plot 

for 5 I\ Rou~hnes 

(obtained from X-ray data) 

Measured Reflectivity Plot 

U4B 

Y.U. Idzerda, V. Chakarian, J.W. Freeland (Naval Research Lab), and C.-C. Kao 

(NSLS). 

Figure 1. TOP: Xlagnetometry loop of Co/Cr/Co trilayer. BOTTOM: Vertical 

correlation of magnetic domains Figure 1. 

5 I1 

I"* 

: 15" 

- 2 :or1 

- 

5 Zi" 

2 7nn 

3i n 

Cnlculntetl Reflectivity Plot 

for NO Rourhnc\q 

(M.l:~:netic and Chemical 

roughne\\ are different)

I Magnetic Moment Extraction from Magnetic EXAFS I U ~ I B 

Y.U. Idzerda, J.W. Freeland, and V.Chakarian (Naval Research Lab) 

Transmission MCD measurements have been extended to the EXAFS region for 

Fe, Co, and Ni films grown in-situ by e-beam evaporation (250-300 A) onto wlpm 

thick semi-transparent parylene for determination of the L-edge magnetic EXAFS 

(MEXAFS). The structure of the deposited films were determined by EXAFS mea- 

surements at the K-edges of these films, indicating that the Fe, Co, and Ni films 

are polycrystalline films in the bcc, hcp, and fcc phases, respectively. The com- 

bined L2,3 spectra can be deconvolved assuming that the LZ and L3 oscillations 

are identical and are offset by the Lz and L3 energy separation and that the Lg 

edge EXAFS (MEXAFS) is weighted by +2 (-1) compared to the L2 edge EXAFS 

(MEXAFS). These weighting factors reflect the relative heights of the Lz and L3 

edge jumps (quantum degeneracy of 2:l) and the phase relation of the MCD (-1:l). 

After the L-edge (M)EXAFS is isolated, it is converted to electron wavenumber, 

k, and fourier transformed (with a k2 weighting) in the usual way to generate the 

radial distribution function, shown in Fig. 1. The first shell position is reproduced, 

but in each case the longer scattering paths are enhanced relative to the first shell 

for the MEXAFS when compared to the EXAFS. Most interestingly, if the MEX- 

AFS first shell intensity is scaled to the EXAFS first shell intensity, this first shell 

ratio scales with the spin moment of the material (see Fig. 2). 

Radial Co-ordinate 

Figure 1. FT Intensities. 

Spin Moment (v,) 

Figure 2. First shell ratio (MEX- 

AFSIEXAFS) for bcc Fe, hcp Co, and 

fcc Ni as a function moment. Solid line 

is a linear fit. 

- 

Site-Specific NEXAFS of Y1-,Ca,Ba2Cu307-,: Role of Apical Oxy- 

gen for High-Temperature Superconductivity 

Photon energy (eV) Photon energy (eV) 

Figure 1. 

- 

U4B 

M. Merz, N. Niicker, P. Schweiss, S. Schuppler (Forschungszentrum Karlsruhe), C. 

T. Chen (SRRC), V. Chakarian, J. Freeland, Y. U. Idzerda (NRL), M. Klaser, G. 

Miiller-Vogt (U Karlsruhe), and T. Wolf (Forschungszentrum Karlsruhe) 

Replacing y3' by Ca2+ in YBa2C~307-~ (YBCO) is an alternative doping mechanism 

to the usual 0 doping. With polarization-dependent 01s and Cu2p NEXAFS 

on detwinned (Ca,Y)BCO single crystals, the hole distribution between the CuOz 

planes and CuOs chains has been identified and hole counts for the orbitals near EF 

have been derived. For a polarization Ella, planar 0(2)2p orbitals are observed in 

01s spectra, while Ellc spectra near Ep pick out contributions form the apical O(4) 

site. For Ella, the spectral weight of the planar Zhang-Rice (ZR) state carrying 

the superconductivity increases with increasing 0 or Ca doping (Fig. 1). Here, the 

electronic structure of the CuOz planes for the ~ ~0.23, y=1.0 and the x=0, y=0.5 

compounds is very similar - unlike in the corresponding Ellc spectra, where the for- 

mer exhibits no intensity at the first peak above EF. In general, Ellc spectra from 

samples with the same y are similar near EF and do not depend on x, showing that 

Ca substitution does not affect the apical site. From considerations like these we 

conclude that, regardless of the 0 content, Ca doping introduces holes exclusively to 

the CuOz planes, leaving the apical O(4) or the chain O(1) site entirely unaffected. 

Most significantly, we find that Ca-doped but 0-depleted samples exhibit no 

superconductivity, independent of the hole count on the planes. On the other hand, 

0 doping increases the hole count at the planar and the apical (and chain) sites 

and restores Tc. Thus, for high Tc not only optimally doped planes are needed; the 

apical hole count is equally important. This result explains the decrease of TFax 

with Ca content, questions the validity of "universal" T, curves [I], and may have 

more general implications for HTSC, e.g., about the need for theoretical models 

involving extra-planar hopping. 

[I] J. L. Tallon et al., Phys. Rev. B 51, 12911 (1995).

Pr and Other Rare Earths in REBa2C~307-y: A NEXAFS Study 

Ella 


U4B 

M. Merz, N. Niicker, P. Schweiss, S. Schuppler (Forschungszentrum Karlsruhe), R. 

Neudert, TvI. S. Golden, J. Fink (IFW Dresden), C. T. Chen (SRRC), V. Chakarian, 

J. Freeland, Y. U. Idzerda (NRL), A. Erb (U Geneva), M. Klaser, G. hEller-Vogt 

(U. Karlsruhe), and T. Wolf (Forschungszentrum Karlsruhe) 

In the family REB~~CU~O~-~ (RE = rare earth, Y), RE=Pr is the only 

orthorhombic but non-superconducting compound. We showed earlier [I] with 

polarization-dependent 01s and Cu2p NEXAFS that for RE=Pr, 02pRE4f 

("Fehrenbacher-Rice", FR) hybridization occurs, removing holes from the energetically 

competing planar 02pCn3d "Zhang-Rice" (ZR) states responsible for superconductivity. 

Now, similar experiments on detwinned REBCO single crystals with 

RE neighboring Pr (La, Ncl) and with substantially smaller ionic radius (Er) were 

perfornletl to further study the special role of Pr among the RE'S and to check if 

some FR hybridization occurs elsewhere in the RE series. 

Spectra with the polarization Ella (Fig. 1) show for all RE investigated (and 

for 0-rich samples) a prominent ZR state while the upper Hubbard band (UHB) is 

small; of course, for Pr transfer of spectral weight to the UHB and FR hybridization 

occurs. Small deviations from this general picture include a tendency for increasing 

UHB intensity with larger RE radius. This is most obvious for La, but cannot be 

thlc to a FR contribution: precisely for La, no further holes can be transferred to a 

~a4.f' orbital. Also, for decreasing RE ionic radius, the threshold energy moves up 

(EF moves relative to the ZR), and an additional strl~cture located at 532-533 eV 

also moves up. This latter feature is also seen for E/lc, appears somewhat isotropic, 

ant1 is assigncd to hybridization effects goverrirtl by the RE site. The extra spectral 

weight Ilc for Pr (arrow in Fig. 2) is a signature for the small but existent outof-plane 

character of the FR hybrid: it has been confirmed by recent theoretical 

work. 

[I] M. Rlerz et al.. Phvs. Rev. B 55, 9610 (1997); NSLS 1996 Activity Report 

Figure 1. 

I Temperature Dependence of MCD Anisotropy of ~ a ~ . ~ ~ r ~ 

J.-H. Park, H.-J. Kim, E. Vescovo (NSLS), C. Kwon, R. Ramesh, T. Venkatesan 

(U. Maryland) 

Soft x-ray magnetic circular dichroism (SXRICD) has been well known to be a 

powerful tool for studying magnetic properties of ferromagnetic systems. SXMCD 

utilizes a core level absortion edges, and thus it is element specific. The obtained 

MCD anisotropy corresponds to the magnetization of the given elements. 

Here we present SXhICD study results of a colossal magnetoresistance material 

Lao.7Sro.3hIn03 including the temperature dependence of its anisotropy. Figure 1 

shows the SXMCD results at RIn L23 edges obtained at 40K from 1900A thick 

epitaxial La0.7Sro.3hIn03 film on SrTi03 substrate. Different from the bulk crystal 

sample, the thin film shows nearly magnetic single domain behavior; low coercive 

field (< 100 Oe) and = 100magnetic moments. The obtained hICD signal is very 

large and the anisotropy (difference cleviclecl by sum) is as large as N 30the line 

shape of the hICD spectrum can bc unclerstood by a model multiplet calculation. 

Nore interesting results were obtained in the study of the temperature dependence 

of the hICD anisotropy presented in Figure 2. The hICD spectra were obtainetl in a 

total electron yield rnotle which has about 50A penetration depth. Thus, the XICD 

anisotropy reflects the magnetization up to the first - 50A, rather than that of the 

whole sample, which can be obtained by SQUID measurements. Interestingly the 

temperature tlependence of the XICD anisotropy is somewhat different from that 

of the magnetization obtained by SQUID, indicating that the magnetization near 

surface is consitlerably different from that of the bulk. 

7 

x 1.66 MCD (p, - p-) 

V 

640 650 660 670 680 690 

Photon Energy (eV) 

Figure 1. Soft x-ray magnetic circular 

dichroism at LIn L2.3 edge measurecl at 

40K well below Tc -. 360K. LICD sig- 

nal is multiplied by 1.66 which is a scale 

factor considering the experimental ge- 

ometry (cos 45") and the helicity (85%). 

i 

0 100 200 300 400 


Figure 2. Temperature dependence of 

the LICD anisotroty (pA -p-)/(pt +p-) 

compared with that of the magnetlzatlon 

obtained by SQUID.

? 

+ 

I ~ a MCD y Studies of Heusler Alloys, NiMnSb and CoMnSb I U4B I 

J.-H. Park, H.-J. Kim, E. Vescovo (NSLS), W. Zhu, B. Sinkovic (NYU), C. Tanaka, 

and J. S. Modera (MIT) 

Since theoretical prediction of half-metallic ferromagnets and observation of large 

magneto-optical Kerr effects in PtMnSb and NiMnSb, interest in Mn-based Heusler 

alloys have been stimulated theoretically and experimentally. The band structure 

calculation predicts that the system is metallic for the majority spin but insulating 

for the minority spin. 

Here we present magnetic circular dichroism (MCD) studies of NiMnSb and 

CoMnSb using soft x-ray absorption spectroscop~ (XAS) at Mn L2.3 and Ni(Co) 

L2,3 edges. ~?~ure shows the XAS spectra forAdifferent' helicities and the cdrr4 

sponding MCD spectra. The XAS data were collected in total electron yield mode. 

As can be seen in the figures, for both systems the XAS spectra exhibit large MCD 

effects at Mn L2,3 edges but very little MCD effects at Ni and Co L2,3 edges, indicating 

that the magnetic moments are mostly induced in the Mn sites. The spectral 

structure of Mn L2,3 edge MCD is very consistent with that expected from Mn2+ 

ions. Most interesting things are observed in the MCD of Ni L2,3 and Co LZ 3 edges, 

which reflect the unoccupied conduction states. The MCD of the Ni L~/LZ edge 

shows positive/negative signals at the pre-edge while that of the Co L3/L2 edge 

shows opposite signals. These results show that the electron states very near EF 

have more maioritv ., " spin * character in NiMnSb but more minority " spin - character in 

CoMnSb. 

7 CoMnSb 

840 660 880 900 760 780 800 820 


- 


-- 

Figure 1. Soft x-ray magnetic circular dichroisms of Heusler alloys, NiMnSb and 

CoMnSb. at (a),(c) Mn L2,3, (b) Ni L2,3, and (d) Co L2,3 edges. 

Characterization of the Charge Carriers in a Double-layered Manganite 

La1.3Sr1.7Mnz07 / u4B I 

J.-H. Park (NSLS), T. Kimura, and Y. Tokura (U. Tokyo) 

Recent success in synthesis of double-layered manganites, La2-~,Srl+z,Mnz07, 

attracted so much attention scientifically and technologically due to their noble elec- 

trical and magnetic properties. Similar to doped manganese perovskites, the double- 

layered manganites exhibits large negative magnetoresistance. Furthermore, these 

have intrisic atomic scale magnetic multi-layer tunnel junctions. Each Ferromag- 

netic metallic MnOz bilayers sheet are separated by a nonmagnetic insulating (I) 

(La,Sr)zOz layer, and thus the system forms a virtually infinite arrays of FM/I/FM 

junctions. 

Here we investigate the characteristics of charge carriers of an x = 0.35 double- 

layered manganite by using polarization dependence 0 1s x-ray absorption spec- 

troscopy. The 0 1s XAS is well known to present the unoccupied conduction states. 

To achieve complete polarization geometry and eliminate optical path variations, a 

single crystal sample in which the sample normal has 45" off from both c-axis and 

ab-plan, and an azimuthal rotation method was used. The figure shows the 0 1s 

XAS spectra for (a) E, and (b) E,b at two different temperature, 25K (FM) and 

150K (PI), and the differences. The XAS spectra show quite different line shape 

for different geometries due to the different dipole transition selection rules; 0 1s 

to 0 2p, for E, and to 0 2p,,, for Eab The system undergoes PI to FM transition 

around Tc TV 130K, and thus the first peak of the difference spectrum reflects the 

charge carriers at the Fermi level in FM phase, analogous to Drude peak in the 

optical absorption measurements. The first peak intensity is quite comparable for 

the two geometries. This result show that the system has comparable in-plane and 

out-of-plane charge carriers in FM phase. The in-plane and out-of-plane charge 

carrier ratio is estimated to be 45 : 55. 

- 25K (FM) 

.... . l5OK (PI) 

- 25K (FM) 

...... 

l5OK (PI) 

/\ Difference (FM - PI) $ Difference (FM - PI) 4 

Photon Energy (eV) - 


Figure 1. Polarization dependent 0 1s x-ray absorption spectra of La1.3Sr~7Mn207 

measured at T = 25K (FM) and at T = 150K (PI). The polarization field of the 

incoming photon lies (a) out of plane and (b) in plane.

? 

bJ 

b~ 

Electronic Structure, Spin State, and Magnetic Properties of 

Lal-,SrxCo03 

U4B 

E. Pellegin, O.C. Rogojanu, G.A. Sawatzky (U. of Groningen), M.H.R. Lankhorst, 

H.J.M. Bouwmeester (U. of Enschede), V. Chakarian, J.W. Freeland, and Y.U. 

Idzerda (NRL) 

The charge-transfer system Lal-zSr,CoO~ exhibits a wide variety of transport 

and magnetic properties as a function of temperature and Sr doping. This is partly 

due to the competition between the crystal field splitting and the Hund's rule eschange 

interaction on the Co sites leading to strong changes in the Co spin state as 

a f~~nction of the above parameters. In Fig. 1 we show the doping-dependent 0 K 

x-ray absorption spectroscopy (XAS) data of (paramagnetic) La1-,Sr,CoOs at 300 

K. The part of the 0 K-edge between 527 and 532 eV is in general interpreted as 

originating from unoccupied 0 2p states covalently mixed with Co 3d states. The 

dramatic increase of the 0 I( prepeak intensity with increasing Sr concentration 

gives evidence for a very strong 0 2p character of the dopetl charge carriers and for 

the charge-transfer character of the Lal-,Sr,.CoO3 system. The former may indicate 

the upcoming of a dG&dominatetl ground state of the Co"+ ions as has already 

been suggcsterl for the fully dopetl SrCoO3 which would be compatible with the 

ferromagnetic ordering of Lal-,Sr,CoO3 for x20.2 below 200 K. The temperature 

tlcpenclcnce of the RIn L-edges of undopcd Lacoo:< is presented in Fig. 2. Between 

15 K and 150 K significant changes can be observed possibly due to the transition 

from the low-spin (S=0) d" gro~lnd state to a mixed-spin (S=0 and S=2) regime. 

For 150 KIT5400 K the systematic changes in thc XIu L data suggest an increase 

of Co"+ ions with a high-spin (S=2) ground state. 

Figure 1. Doping-dependent 0 K absorption 

eClges of Lal-,Sr,~o~s mea- Figure 2. Temperature-dependent 1In L 

sured at 300 K. 

absorption edges of LaCo03. 

Soft X-ray Bragg Scattering study of a Ce/Fe multilayer at the R.14 

edge of Ce I u4B / 

L. Skve, F. Bartolomk, J.M. Tonnerre, D. Raoux (LCG-CNRS), V. Chakarian 

(NRL), C.-C. Kao (NSLS) 

X-Ray resonant magnetic scattering (XRMS) experiments have been performed 

on a metallic multilayer at the i\I4 edge (2p1/2 + 4f transitions) of Ce in a Ce/Fe 

multilayer, using a linearly polarized soft X-ray beam together with a transverse 

scattering geometry. A Ce.- ; /Feqn ; was chosen in order to provide a sufficient 

1Ut. a"*, 

magnetic asymmetry ratio (the polarization of the Ce 4f shell is assumed to be 

located at the interface with the Fe layer according to XhICD experiment) and a 

sufficient number of Bragg peaks orders arising from the multilavered structure. 

Despite the huge absorption at this edge and the linked large anornalons scattering 

factors (up to 800 r, for f' and 400 r, for f'). we succeeded in measuring the 

four first Bragg peaks, the 4th order Bragg peak lying right around 45' with still 

measurable intensity. Rather large asymmetry ratios have been measured : up to 

10 % to be compared with the 1.5 % amplitude of the XhICD signal measured on a 

similar sample. This first resonant magnetic reflectivity experiment on a 4f element 

ascertains the possibility to st~~dy rare earth elements by either soft X-ray magnetic 

reflectivity or diffraction on multilavcrs at thc hI edgrs of rare earths. Thc nonconstant 

evolution of the asymmetry ratio (mainly the change in shape) is directly 

linked to a non-constant profile of the 4f spin polarization across the Ce layer. A 

q~lantitative analysis, using the 4 ortlers of diffraction is untlerway to determine the 

4f polarisation through thc Cc layer. 

- 5 10 15 20 25 30 35 40 45 

Incident Angle (O) 

Figure 1. Three first resonant magnetic Bragg orders of a Ce/Fe multilayer at the Ce 

114 edge recorded in a transverse geometry. The difference spectra obtained for the 

two opposite directions of the applied magnetic field is also displayed. =\symmetry 

ratio is of the order of a few percents.

( Soft X-Ray Resonant Magnetic Reflectivity Study of Thin Films 1 U4B 1 I Temperature Dependence of the Fe L-edge Magnetic EXAFS I U4B 1 

L. She, F. Bartolome, J.M. Tonnerre, D. Raoux (LCG-CNRS), V. Chakarian 

(NRL) and C.-C. Kao (NSLS) 

Soft X-ray resonant magnetic reflectivity measurements have been performed 

on thin films. Reflectivity scans have been recorded at the Fe L2,3 edges on a 

Wq7 ; /FeQ1 ; /W1 34 ; trilayer both versus the beam incident angle on the sample 

(re%e>tivGAscans]-and versus the photon energy (spectroscopic scans). A linearly 

polarized beam, together with a transverse geometry (magnetic field applied perpendicular 

to the reflection plane) have mainly been used. In that case both state of 

light (a and n polarisation) remain independent polarization states through the sample, 

easing to introduce the effect of roughness. Thus the resolution of the Maxwell 

equations for a stratified media, including the calculation of the dielectric tensor 

using regular Fe XMCD spectra and the various interfacial roughness, allows to simulate 

accurately the X-Ray Transverse Kerr spectra for both the isotropic intensities 

and for the magnetic one, through the Asymmetry ratio, R= (I+-IP)/(I++1~). The 

asymmetry ratio amplitude are found to be of the order of 5-20 % at the Fe L2,3 resonance, 

to be compared to the typical 1% in conventional TMOKE on 3d transition 

metals. We also study a Ir / Feo.sMn0.l / Ir trilayer, epitaxially grown on a MgO 

substrate. Asymmetry ratio, up to 25 % measured at the Fe L edges are accurately 

simulated using the standard bcc Fe XMCD spectra, allowing to ascribe a 2.1 p~ 

magnetic moment. A signal of 1 % has been recorded at the Mn L edges ascertaining 

the magnetic ordering of Mn atoms in such a solid solution. Simulation of the 

Mn L edges magnetic reflectivity plead for an antiferromagnetic orientation between 

the Mn net moment and that of Fe, with an equivalent coercitive fields recorded 

through element specific hysteresis loop measurements in reflectivity mode. 

J.M. Tonerre et al, submitted to J. Appl. Phys. (7th Joint MMM Conf. Proc.). 

L. Shve et al, to be published. 

-4 

"'0 10 20 300 LO 20 30 

Incidence mgle (') Incidence angle (O) 

-1.5- --1.5 

690 700 710 720 730 690 7M 710 720 730 

Energy (eV) Energy (eV) 

Figure 1. Left : experimental measure- Figure 2. Left : Experimental measure- 

ment of the reflected intensity for both ment of the reflected intensity for both 

magnetic field orientations and Asym- magnetic field orientation and Asymme- 

metry ratio. Right : calculated ones at try ratio. Right : calculated ones at the 

the L edges of Fe in a W/Fe/W trilayer L edges of Fe in a W/Fe/W trilayer as a 

as a function of the incident photon en- function of the incident angle for a 703.2 

ergy at a 5 degree incident angle. eV energy. 

I - I I 

H. Wende, J.W. Freeland, Y.U. Idzerda (NRL), L. Lemke, and K. Baberschke 

(Fkeie U.) 

This work presents the first systematic investigation of temperature dependence 

of the Magnetic EXAFS (MEXAFS). We chose a polycrystalline Fe thin film of 500 

A as a model system as it is known that the Debye model describes the temperature 

dependence of the spin averaged EXAFS reasonably well. The deconvoluted exper- 

imental EXAFS data (X and FT) of the L3 edge, taken in transmission through 

the Fe film, are shown in Fig. la and lb. Similarly, the deconvoluted MEXAFS 

data (chi and FT) are shown in Fig lc and Id. A qualitative comparison of the 

MEXAFS data to EXAFS data shows that the main peak position of the Fourier 

transforms (Fig. lb and Id) is the same for both cases and the temperature depen- 

dent damping is comparable. The clear temperature dependence of the experimental 

data was fitted with the correlated Debye model yielding a Debye temperature of 

OD = (520 f 40)K (see Fig. 2) in good agreement with calorimetric measurements 

for the bulk system (O~(ca1orimetric) = 470K). The Debye model analysis of the 

MEXAFS temperature dependence results in a value of the 'magnetic' Debye tem- 

perature of OD, = (400 f 40)K, showing that the temperature dependence of the 

MEXAFS data is even stronger than in the EXAFS. Although the measurment 

temperatures are far below the Curie temperature of Fe, we have found an even 

stronger temperature dependence for the MEXAFS compared to the EXAFS. This 

shows that the temperature dependence of the MEXAFS is not only determined by 

the temperature dependence of the magnetic moment, which should be constant in 

the investigated temperature region (70K to 400K), but also by the relative thermal 

vibrations of the absorbing atom with respect to the backscattering atom. 

0 100 200 300 400 500 


Figure 1. The T dependent deconvolved Figure 2. The T dependence for the 

Fe L3 EXAFS data (a,b) in comparison nearest neighbor distance (RI) of the 

to the deconvolved L3 MEXAFS data EXAFS and MEXAFS data. Also shown 

(cd. 

is the Debye model (lines).

? 

h3 

,P 

Characterization of Bitumen-Polymer h'lixtures by Infrared Mi- 

crospectroscopy 

J-L. Bantignies, G. Fuchs (ELF Atochem, France) 

U4IR 

Bitumens are the heavy organic fraction of petroleum products. The main industrial 

applications of these materials are road surfaces and for such applications 

polymers are added to the bitumen to improve the mechanical properties, which in 

turn depend on the homogeneity of the mixture. Any characterization of the mixture 

using infrared microspectroscopy (IAIS) with a conventional (thermal) source 

is limited to a lateral resolution of about 30 microns, which is inadequate due to 

the 1 and 50 micron length scale of heterogeneities in the mixture. The situation 

is much improved using synchrotron radiation, however. To prepare samples for 

the microscope, the bitumen-polymer mixtures were first heated in a oven at 353K 

ancl then spread on 2 nun thick BaF2 pellets. This method does not allow control 

over the thickness. Fig. 1 shows the IR spectrum of a Bitumen/polyrner mixture. 

The 1377 cm-' band (dCH2-CH3) is a signature for the bitunlen and the 967 cm-' 

band (gCH butadiene) is assigned to the polymer. The mapping experiments were 

rr~atle in transmission mode with 2 cnlp' resolution with 128 pixels per spectrurn 

using 16x16 micron apertures and 8 micron steps. After mapping, the integrated 

absorbance (11-1) of both bands was calculated as a fnnction of the position. As the 

thickness of the sample was not homogeneous, the ratios of these values (IA 967 

cmL / IA 1377 cm-') mas calculated for each position and yielded the image in 

shown Fig. 2. The contows represent increments of 1.1% variation of relative concerltratiorl 

of polymcr in the matrix of hiturnen (concentration of the polymer in the 

hitumer~ rnixt~lrc of 5 96.). The spatial resolution is limited by the diff'raction lirrlit 

of the ~vavclcngth of thr polymer barltl at 10.3 microns and tht: size of the apertures. 

Therefore me are able to observe heterogeneity of the relative concentration of the 

polymer in the bit~lmcn for thc n~echanically nlixetl saruplc of 9%. This scale of 

lleterogcneity (order 15 microns) is irnpossihle to observe by sing a convent,ional 

source. 

Figure 2 A\bsorbance contonr map of 

Wavenumber (cm ') 

the prepared biturne-polymer mistwe 

for the ratio of the 967 cmp' band (poly- 

Figure 1. IR spectrum of the mixture of mer) and the 1377 cm-' band (bitu- 

Bitumen-polymer. 

men). Darker regions represent Ion-er absorption. 

Infrared h'licro Spectroscopy by Using Synchrotron Radiation Appli- 1 U4IR I 

cation to hlicrostructural Hair Characterization 

J-L. Bantignies, G. Fuchs, (ELF Atochem, France), D. Lutz, S. Marrull (Yves 

Rocher, France) 

Infrared Microspectroscopy (IMS), using thermal sources, is widely employed 

in the cosmetic industrial environment for the analysis of hair. Nevertheless, the 

lateral resolution achieved (about 30 microns) does not allow a local characterization 

(few microns resolution) of the structure of the hair. The IR synchrotron source 

overcomes this limitation ancl a chemical imaging of the hair at the micron level is 

herein presented. 

From the morphological point of view, the human hair shaft structure consists 

of three main comporlents (Fig. 1). The hair is typically composed of an inner 

core, the meddla ( 10 microns diameter), mhich is snrro~~nded by the cortex which 

constitutes the main part of the bulk of the fiber. The outer layer, which is exposed 

to the environment, is the cuticle with an average thickness of 5-10 microns. 

Chemically, hair mainly consists of keratin, a protein highly cross-linked by the 

amino acid cystine giving well defined arnide signatnrc in the middle infrared. 

For the IhIS experiments, samples were prepared by embedding hairs in polymer 

blocks and sectioning them using a rnicrotonie. The cross-sectioned cuts were on 

the order of 6 microns thick (Fig. 1). The polymer was chosen to have bands well 

away from those of the hair samples. 

The hair section shown in Fig. 1 was spectroscopically mapped with a lateral 

resolution of 6 microns. The integrated absorbance of the arnide A band (3290 

cnp1) was then extracted and a contour niap showing thc absorbance of this band 

as a function of position in the sample is shown in Fig. 2. Since this band is present 

throughout the hair, but at differing corlcer~tratious in the vario~~s components, 

the cuticle, cortex and mctlulla are all revealed ir~ this map. The variations in 

absorbar~ce mhich give the contrast are consistent with the differences in protein 

composition between these components. The microscope will now be l~sed to stntlv 

the irtfluence of dyes and cosmctic reagents on the structure of hair samples. 

1. ti^^ of the hair 

a Lair for the arnide -1 band (3290-cm- 

1). Darker regions represent lower ab- 

sorbance.

The c-Axis Reponse of Y1-,Ca,BazCus07-s Single Crystals Studied 

by Far-Infrared Ellipsometry 

U4IR 

C. Bernhard, R. Henn, A. Wittlin, and M. Cardona (Max-Planck-Institut fuer 

Festkoerperforschung) 

We studied the c-axis reponse of Yo.s~Cao.14BazCu307-a crystals by far-infrared 

ellipsometry. The substitution of y3+ by ca2+ introduces extra hole carriers into 

the CuOz planes. Therfore, the strongly overdoped regime can be explored for Y-123 

and the oxygen content and metallic character of the CuO chains can be varied while 

the doping of the CuOz planes is kept constant. This provides a unique possibility 

to test if the unusual frequency- and temperature dependence of the electronic c- 

axis conductivity a,(w,T) is determined either by the charge dynamics of the CuOz 

planes or rather by the spacing layers including the CuO chains. Fig. la and lb show 

alc(w,T) for two optimally doped crystals, a Ca-free and almost fully oxygenated 

Y B ~ ~ C U with ~ O Tc=Tc,,,,=92 ~ . ~ K and b] Ca-substituted and oxygen deficient 

Y0.s6Cao.14Ba~Cu30~., with Tc=Tc,,,,=85 K. The absolute value of the electronic 

part of al, is clearly higher for the Ca-free crystal. The frequency- and temperature 

dependence of al,, however, is very similar for both crystals. Notably, for the Ca 

substituted crystal there occurs no sign of a "pseudogap-like" suppression of u1, in 

the normal state as it has been observed for the oxygen deficient and underdoped 

Ca-free crystals. This demonstrates that the 'pseudogap-effect' is not related to the 

electronic properties of the spacing layer (the oxygen deficiency of the CuO chains). 

Instead, our results imply that the "pseudogap-effect" is intimately related to the 

underdoped state of the CuOz planes, i.e. the charge carriers (in the normal state) 

are confined to the CuOz planes. 

A rather different behavior is observed for the strongly overdoped 

Y0.8GCao.14Ba2C~306.~~ crystal with Tc=63 K for which al,(w,T) is metallic in 

the normal state (see Fig. 2a). The relaxation of the charge confinment in the 

normal state is accompanied by two remarkable effects in the SC state (Fig. 2b). 

Firstly, the the SC gap is strongly reduced since the onset of the reduction of 

spectral weigth (due to the condensation of the carriers into a delta function at 

zero frequency) is suppresed to 2A=420 cm-l from 2A=620-650 cm-' in case of 

the optimally doped crystals. Secondly, there remains a large fraction of unpaired 

quasiparticles within the SC gap. 

Figure 1. Figure 2. 

Infrared Microspectroscopy Studies of Electronic and Electro-Optical 

U4IR 

Materials 

L.G. Casagrande (Northrop Grumman Corporation) 

The performance of electronic and electrooptical materials and devices is de- 

pendent on their physical and chemical quality and uniformity. These materials 

can be difficult to fabricate, and frequently contain microscopic defects and in- 

homogeneities such as included secondary phases which can detract from device 

performance. Understanding the nature of such defects is vital to reducing their 

formation during fabrication and to determining their effect on device performance. 

We have used the Fourier-transform infrared microspectrometer originally on the 

midinfrared beamline at port U2B, now on beamline U4IR, to study these defects 

in the non-linear optical material AgGaSez. We have spatially mapped 100 pm x 

100 pm regions of this material containing microscopic defects -10 to 20 pm across. 

The infrared beam was shuttered to a 12 pm square and successive spectra were 

obtained in 10 pm steps. Figure 1 shows spectra obtained from various locations in 

such a region. The average transmission spectrum is generally representative of this 

material without an anti-reflection coating, although it deviates slightly from the 

standard FTIR transmission spectrum of the entire sample. For spectra obtained 

away from the defect, the spectrum is nearly identical to the average spectrum. 

However, for spots at or near the surface defect, decreases in transmission occur 

which may indicate the presence of optically absorbing impurities. The minimum 

transmission in the spectrum at the second on-defect point occurs at v=2941 cm-l, 

and the map of transmission at this frequency vs. location is shown in Figure 2. 

This shows the unique potential for IR microspectroscopy to correlate microscopic 

chemical analysis with optical microscopy techniques. Additional work to determine 

the nature of these defects is underway. 

44 1 1 I 

4000 3500 3000 2500 2000 1500 1000 

Wavenumber (cm-') . . 

Figure 1. Individual FTIR transmis- 

Figure 2. Map of transmission at 2941 

cm-l for spectra from region in Fig, 1 

si0n spectra for different locations in showing decrease in T at and around sur- 

AgGaSez map compared to map average. face defect.

? 

h3 

o 

Mapping the Chemical Composition of Subchondral Bone in Os- 

teoarthritis Using Infrared Microspectroscopy 

U4IR 

h1.R. Chance, L.hl. hliller, D. Hammerman, R. Stanley (AECOhI), and C. Carlson 

(Bowman-Gray Sch. of Ned) 

Osteoarthritis naturally occurs in young adult female cynomolgus monkeys and 

it closely resembles the human disease. In the knee joint, it is characterized by the 

breakdown of the articular cartilage and marked thickening of the adjacent subchondral 

bone. There is a strong correlation between the severity of the osteoarthritic 

lesions and the thickness of the subchondral bone, but it is unclear why this is the 

case. \\'e question whether the newly-deposited subchondral bone has a different 

chemical structure/composition compared to the older bone, leading to the development 

of osteoarthritis. Presently, we are using infrared micro-spectroscopy to 

study the chemical composition of the subchondral bone as a function of snbchondral 

bone thickness. \Ve are able to map the subchontlral bone from the articular 

cartilage (older bone) to the marrow space (newer bone) and compare their chemical 

compositions. Bone proteins. pri~narily collagen, absorb infrared light in the 

1450 - 1650 cmp' region. An intense, broad band from 900 - 1200 cm-' and a 

double-peaked band from 500 - 650 cmL are attributed to bone mineral, i.c. phosphate 

ions in hydroxyapatite. A small absorption centered at 875 cnl-' arises from 

carbonate-substituted hytlroxyapatite. These bands are sensitive to mineral content 

(i.e. carbonate, phosphate, acid phosphate), mineral crystallinity, and the 

content/nature of the organic matrix. They are cwvc-fit and/or integrated antl 

cornparetl as a function of (1) rtate of the bone, i.e. thicknrss of thtl subchondral 

plate, antl (2) age of hone, i.c. position in the subchondral plate. 

Anharmonicity of Low Frequency Vibrational Modes in Amino Acid 

Polymers 

MR. Chance, L.M. hiiller, Q. He, and S. Schwartz (AECOM) 

U4IR 

Low frequency (collective) modes in proteins (--10-600 cm-l) have received considerable 

attention because it is thought that domains or sub-domains in proteins are 

involved in correlated motions on picosecond timescales. It is clear that motions at 

these frequencies make an important contribution to the mean-square displacement 

of atoms from their equilibrium (vibrational) positions. Thus, these motions are the 

first steps in functionally important motions leading to large-scale conformational 

changes. Such changes are critical to structural and functional processes like protein 

folding, cooperativity, and protein-protein or protein-ligand interactions involved in 

electron transfer, enzyme catalysis, antl signaling. Polv-amino acids provide a model 

system for understanding collective rnotles in proteins. By polymerizing different 

amino acid monomers, varying secorldary and tertiary structures can be created 

and studied with far infrared absorption spectroscopy. They provide a controllccl 

method for identifving and characterizing anv "breathing modes" attributable to 

various (a-helical or (6-sheet type structures in proteins. \Ve have also obtained 

the far-infrared spectra of poly-L-phenylalanine, poly-L-alanine, poly-L-tryptophan, 

antl poly-L-leucine from 10 to 295 K in 20 K increments. The results demonstrate 

(1) there are several (ranging from 4-10, depending on the poly-amino acid) low frequency 

modes in the far-infrared region, (2) the bands below ~ 200 cmp' all increase 

in frequency with tlecrcasing temperature, and (3) this temperature-tlepentlence increases 

with decreasing band frequency. Tt~ese results suggest that these rnotles 

are highly anharmonic, consistent with various computational studies. Currently, 

curve-fitsting analysis is bcing used to aid in the itlerltificatior~ of various rnoties, 

assig111nent of their origins, antl their sensitivity to ternpcrature.

Chemical Composition of Bone Osteons in Osteoporosis and Os- 

teopetrosis In Sztu 

U4IR 

M.R. Chance, L.M. Miller (AECOM), R. Mendelsohn (Rutgers U.), and A. Boesky 

(Hosp. for Special Surgery) 

The unique strength and rigidity of bone arises from a combination of organic 

components (primarily collagen) and inorganic (mineral) components. Over a lifetime, 

bone is continuously remodeling itself. Old bone is eroded away in a tunnellike 

fashion by osteoclasts and new bone is deposited layer-by-layer in the "tunnel" 

by osteoblasts. From a cross-sectional view, these new layers of bone, collectively 

termed an osteon, appear as series of concentric circles through a microscope. A typical 

osteon measures 200 (pm in diameter, where the youngest bone is at the center. 

In many diseased states of bone, there is an imbalance between bone production 

and resorption, resulting in overgrowth (osteopetrosis) or undergrowth (osteoporosis) 

of bone. To date, it is unclear whether the chemical composition of the bone 

in a diseased state is the same as normal bone. Using infrared micro-spectroscopy, 

we are able to visibly and chemically image individual osteons in terms of growth-, 

site-, and age-dependent variations in mineral content (i.e. carbonate, phosphate, 

acid phosphate), mineral crystallinity, and the contentlnature of the organic matrix. 

A significant advantage of this technique over other chemical methods is that 

the bone does not need to be homogenized before testing; we are able to study 

cross-sectional samples of bone in situ at a resolution of 3-5 (pm. In this study, 

we present a comparison of human osteoporotic bone to osteopetrotic bone. Early 

results show some similarities and also significant differences between osteopetrotic 

and osteoporotic bone. For both diseased states of bone, the ratios of phosphateto-collagen 

and carbonate-to-collagen concentrations are similar and these ratios 

increases as bone matures (from the center to the periphery of the osteon). Also for 

both, the phosphate ions (PO:-) are replaced by other anions such as carbonate 

(~0;~) as bone ages, i.e. the hydroxyapatite becomes non-stoichiometric. However 

in contrast, we observe significantly more COi- substitution in osteoporotic bone 

than osteopetrotic bone as the bone matures. 

IR Microspectroscopy of Laser Drilled Graphite/BMI Structural 

Composite Laminates 

D. Di Marzio, L. G. Casagrande, and J. Clarke (Northrop Grumman) 

U4IR 

Sound attenuation is a major concern in both military and commercial aerostruc- 

tures. Arrays of microholes drilled into nacelles and other aircraft components can 

effectively muffle engine noise. The use of advanced composite structural materials 

present a new challenge for this sound reduction technology. In this project, an auto- 

mated laser drilling system is used to produce hole arrays in graphitelbismaleimide 

composite panels. Cylindrical holes have been produced with a uniform diameter of 

30 mil and minimal heat damage to the surrounding composite matrix. Reflectance 

IR microspectroscopy was used to confirm the integrity of the bismaleimide used 

to hold the graphite fibers together near the laser drilled holes. Cross sections of 

the laser drilled holes were prepared, and a 50 pm IR beam diameter was used to 

scan across the cross sectioned holes. Figure 1 shows a schematic of the IR mea- 

surements of the cross sectioned panel. Figure 2 shows the dispersion corrected 

absorbance from a location far from the hole and a location next to the hole. The 

carbonyl peak near 1750 cm-l, which is an indicator of relative oxidation for the 

bismaleimide, shows a small increase in integrated area in the region next to the 

laser drilled hole, as compared to the region far from the hole. A small amount 

of oxidation is expected next to the hole due to local laser heating. Spectra taken 

close to, but not next to the hole, exhibit no bismaleimide oxidation. Using IR 

microspectroscopy, automated laser drilling has been demonstrated as an effective 

method for fabricating sound attenuating microhole arrays in structural composites. 

IR Spot IR Spot 

Away From Hde Next to Hole 

/' 

T 

Laser 

Drilled Hole 

Wavenumber. crn-' 

Figure 2. Micro IR spectra of cross sec- 

Figure 1. IR sampling schematic for tioned laser drilled composite panel. Relaser 

drilled composite panel cross section. 

gions near the holes show little or no bismaleimide 

oxidation. 

. . 

. . . ' . . . ' I . . ' . . . ' . . . ' . . . ' , . , ' . , . 

0 20100 18100 16b0 1400 12100 1600 840 660 

I

? 

h) 

X, 

IR Microspectroscopy of Plasma Sprayed Liquid Crystal Polymer 

U4IR 

Films * 

D. Di Marzio, L. G. Casagande, J. Clarke (Northrop Grumman Corporation), J. 

Brogan, S. Sampath, and H. Herman (SUNY) 

Commercial and military marine and aerospace structural materials can experience 

significant damage due to environmental factors such as oxidation, corrosion, 

UV exposure, and fouling. Protective coatings are needed to provide a barrier to 

these damaging environmental effects. TVe are currently developing a plasma spray 

process to deposit a coating of liquid crystal polymer (LCP) onto composite structural 

components. LCP films have been demonstrated to be highly impervious to 

oxygen a ~ moisture ~ d penetration, and they exhibit a high degree of mechanical 

strength. LCP powder is fed into a plasma spray gun, and the powder particles are 

melted antl propelled at high velocity to the part to be coatecl. Figure 1 shows a 

schematic of the plasma spray process. IR ~nicrospectroscopy was used to determine 

the degree of LCP particle oxitlation antl burning on a local scale as a result of the 

plasma spray process. Figure 2 shows the IR reflectance spectra of uncharred and 

charred LCP particles in a plasma sprayed coating developed early in the program. 

The IR spot size was 50 pm. The ~incliarretl particles exhibit a strong organic 

vibrational spectrum, especially below 2000 cm-I. The charred particles show a 

dramatic reduction in the organic signature, and they exhibit a reflectancr yectrurn 

more characteristic of purr carbon. Dramatic improverner~ts have since been 

rnatle in the rctl~iction of varticlc oxidation and burning ill the tlevelopnlent of the 

LCP plasma spray process. 

'This work was partially supported by the NSF hlaterials Research Science & 

Engineering Center, Center for '!?herrr~al Spray Rrsenrch. SUNY at Stony Brook. 

Plasma 9pnv Gun 

-- 

r- --- 

L -----. 

C~atlnz ,- Yuhseate 

/' 

4 

LCP Potvder 

.................................... 

4obo 3ho 3doo 25'00 mbo tsbo ~doo 

Feed Wavenumber. crn-' 

bdentification of Organic Compounds in the ALH84001 hteteorite I XlA, I 

I from Mars I U4IRI 

G. J. Flynn (SUNY at Plattsburgh), L. P. Keller and hI. A. hliller (MVA Inc.) 

McKay et al. [I] s~!ggest the ALH84001 meteorite contains evidence of possible 

ancient biological actlvlty on Mars. One line of evidence is the concentration of 

polycyclic aromatic hydrocarbons (PAHs), frequently produced by the decay of 

living material. occuring in close proximity to magnetite and sulfide similar in size 

and shape to those produced by terrestrial bacteria [I]. 

We employed the Scanning Transmission X-Ray hIicroscope on beamline X1A to 

determine the bonding state(s) and the spatial distribution of the carbon in ultramicrotome 

thin-sections of carbonates globules antl the rims, where the magnetites 

arid sulfides were found, on these carbonates from ALH84001 [2]. Both the carbonate 

and the rim sections contained carbon-rich regions, but each gave a different 

C-XANES spectrum, suggesting the major carbon-bearing compound mas different 

in the rim and the carbonate [2]. TVe then examined the same samples using a 

Spectra-Tech micrc-Fourier Transform Infrared (FTIR) spectrometer. on beamline 

U4IR, to identify the carbon compo~~~lcls. 

Transmission Electron hIicroscope (TEhI) examination of the rim samples inclicatetl 

were composed of feltlspathic glass antl contained micron-size chromite, ard 

regions of fine-grained magnetite antl sulfide. The FTIR spectra of the rim snrnples 

showed a broad absorption near 1000 cmpl, characteristic of silicate glass, antl 

two weaker features at 2918 cm-I ant1 2850 cm-I. These two features arc consistent 

in position antl relative depths wit11 the symmetric antl asyrrlmetric stretching 

vibrations of the C-Hz in aliphatic hytlrocarbons. 

The FTIR spectra of thc carbonate globule showed a narrow aahsorption at about 

1500 cm-I, characteristic of carbonate, antl a weaker absorption at 2964 cml. Two 

even weaker features appear at 2920 cmL and 2850 cm-'. The feature at 2964 cml is characteristic of the C-Hs asymmetrical stretching vibration. Although a weaker 

C-H:, symmetrical stretching vibration generally occurs near 2870 cm-', this feature 

is absent in the carbonate globule spectrum, and is suppressed in certain cornpountls 

containing C-Hs groups. One particularly good spectrum of the carbonate globule 

sample appears to show a weak. broad absorptior~ over the rangr 2990 cmpl and 

3060 cm-I. Follow-up measurements, to determine if this featlire could indicate the 

detection of C-H stretching vibrations of a n~ixture of PAHs. which would have an 

absorption near 3030 cnL, arc in progress. 

These preliminary results confirm that high concentrations (of order 1 to 5 percent) 

of organic carbon are associated with the carbonate globules and rims in 

ALtI84001. and further confirm the STSSI observation that the rim antl the carbonate 

globule contain different types of carbon. The latter result seems to rule 

out the simplest form of organic contanlirlation of XLH8-1001. simple evaporation 

of an organic-rich fluid. which would be expected to leal-e the same residue in both 

the carbonate globules antl the acljacent rim material. although selective. mineral 

svecific. contamination cannot be excluded. 

References: 

1) 11cKay. D. S.. et al. Science. 273. 924-927. 1996. 

2) Flynn. G. J. et al.. Meteoritics. 32. -14G-1-17. 1997.

Experimental Check of the Diffuse Scattering of Conduction Elec- 1 U41R I 

trons by Adsorbates on Metallic Surfaces 

M. Hein and A. Otto (U. Duesseldorf, Germany), P. Dumas (LURE and LASIR- 

CNRS-France) and G.P. Williams (NSLS) 

- - 

The initial scientific moaramm at the U4IR beamline was dedicated to the adsorption 

of molecules on metallic surfaces. It was shown, in the early go's, that two 

unexpected features, namely an antiabsorption band accompanied by a broadband 

IR reflectance change, are related to vibrational dynamics at surfaces. In order 

to account for these observations, a theory, mainly developped by B.N.J.Persson, 

suggested that there is a friction force between the collective motion of the adsorbate 

~arallel to the surface, and the substrate conduction electrons, leading to the 

broadband IR reflectance change (when the frequency of the IR light departs from 

that of the collective motion), and to a abrupt changes of the reflectivity (antiabsorption 

band)- when the frequency of the light coincides with the frequency of the 

collective motion of the adsorbates. This can be viewed as the loss of conduction 

electron diffuse scattering, (e.g. a change in the resistance of the metallic film) 

by the adsorbate, which pays the role of a static impurity potential, breaking the 

translational symmetry at the surface. 

Confirmation of the model , and in particular the role of the lifetime of the adsorbate 

vibrational mode, is of critical importance, and was addressed by simultaneous 

measurements of the DC resistance and broadband IR reflectance changes for CO, 

0 and Cu on Cu(ll1) thin epitaxial films, grown on Tion. By varying the thickness 

of the film, and the nature of the adsorbate, we have shown: 

I- That the shape of broadband IR reflectance change is well accounted for by 

the theoretical model (Fig. 1) 

2- There is a linear relationship between the IR reflectance change and the resistance 

change, ( Fig2), as predicted by the diffuse scattering model: 

A Rp / R = (4ne2/mccos(8))[t Ap (t)] 

where ( A Rp / R) is the reflectance change at the asymptotic limit, n is the 

number of conduction electron per atom, m the electron mass, t the thickness of 

the film and Ap the resistivity change. 

~ - 

om t 

o SO lao rm am 

I 

rm 

Frequency 

Figure 1. Broadband IR change for CO 

adsorbed on Cu(ll1) film, at 80K, as a 

function of exposure. The line through 

the data is a fit according to the theory. 

Figure 2. Linear dependence of the 

broadband IR reflectance change, and 

the thickness x resistivity change for dif- 

ferent adsorbates. The common slope is 

an additional proof of the validity of the 

model, as it should depend only on the 

substrate. 

Spatially Resolved Characterization of Coal Heterogeneity with Syn- 1 UlIR I 

chrotron Infrared Microspectroscopy 

- 

F.M. Hoffmann (SCI-MED), P. Dumas (LURE and LASIR-CNRS, France), G.P. 

Williams (NSLS) and J. Paul (Bilkent U., Turkey) 

Coal is a very complex material consisting essentially of carbon ring structures 

(coal macerals) and minerals (alumino silicates minerals with attached H20 and OH 

groups). Each of these groups can contain many different components and elemental 

compositions. In coal liquefaction the coal component is hydrogenated with differ- 

ent precursors for MoS2 and other sulfided hydrogenation catalysts. The dispersion 

and the location of these precursors is an important factor in controlling the activity. 

The hydrogenation catalyst, which produces hydrogen, should be located in close 

proximity to the coal macerals to facilitate the reaction of the hydrogen with the 

coal. Therefore, a spatially resolved characterization of the dispersion and location 

of the catalytic precursors is of great importance. The difficulty of performing IR 

spectroscopy on coal samples derives from the high complexity and heterogeneity 

of the material. The particulate samples of coal used for infrared analysis must be 

finely ground because of the high absorbance of the coal. Because of the different 

derivations from biological matter the IR spectra obtained from pulverized samples 

give average information rather than being characteristic of any individual compo- 

nent in the coal. In the present work we have utilized IR synchrotron radiation on 

the U4IR beamline to perform Infrared microscopy of coal samples. Coal particles 

from 20-100 micron in diameter are characterized at a special resolution of 6 x 6 

microns. Fig. 1 shows an optical micrograph of a typical coal particle together 

with an infrared spectrum obtained from the central region of the sample where 

both maceral and mineral constituents are present. Surface mapping of the entire 

particle shows a different distribution of the macerals and for the minerals in this 

particle, as indicated by the intensity profiles of characteristic C-H bands at 2950 

cm-' and 0-H bands at 3610 cm-l. Further work will investigate the distribution 

and dispersion of precursors for hydrogenation catalysts on these particles. 

C-H - 2900 cm-' 0-H - 3610 cm-'

? 

W 

o NOz Activation and Alkali Compound Formation I U4IR 

F.M. Hoffmann, (SCI-MED, New York), G.P. Williams (NSLS) and J. Paul (Bilkent 

University, Ankara, Turkey). 

The activation of C0z and NO2 are important elementary reactions in catalysis 

and environmental pollution control. Previous work on the activation and com- 

pound formation of COz by alkali metals has shown the formation of potassium 

oxalate K2C204 and its subsequent decomposition to carbonate [I]. The present 

work investigates the activation of nitrogen dioxide in the presence of potassium. 

The experiments were conducted by evaporating potassium in the presence of NOz. 

Both the pressure of NO2 and the evaporation rate of the K could be controlled thus 

allowing to control the stoichiometry and providing selectivity for certain interme- 

diates. The results presented in Fig. 1 show a typical reaction sequence obtained 

under NO2 saturation conditions. The vibrational spectra obtained during evapora- 

tion show the formation of N20.1 at low temperature (90K). Subsequent annealing 

of the layer induces decomposition of the layer to nitrate. Changing the K:NOz 

stoichiometry reveals more complex tlecompositiori pathways, which are currently 

investigated with temperature-programmed time-evolved IR spectroscopy. 

[I] F.hI. Hoffmann. D.G. Van Campen, G. Williams antl .J. Paul, Surface Sci., 

suhmittetl. 

2000 1000 

Wavenurn bers (m-1 ) 

Figure 1. Time evolved vibrational spectra obtained during the reactive evaporation 

of at SO2 saturation on Cu(100) (T=SOK) 

Sifu Synchrotron Far Infrared Spectroscopy of the Electrochemical I UlIR I 

I Interface * 

C.A. Nelendres (ANL), G.A. Bowmaker (U. of Auckland, New Zealand) and J.M. 

Leger (U. de Poitiers, France) 

The objective of this program is to elucidate the structure of the elec- 

trode/solution interface. as well as those of electrochemically formed surface films 

and adsorbed layers. Far infrared spectra of the surface films formed upon anodic 

oxidation of copper have been obtained "in-situ" for the first time in aqueous solu- 

tion environments using a synchrotron source. The spectroelectrochemical behavior 

of copper was studied in NaOH antl in a dilute solution of KSCN in perchlorate. 

The oxide film at -0.05 V vs. SCE in 0.1 hI NaOH solution has been identified as 

Cu20. In the passive region at 0.3 V, CuO and Cu(OH)2 appear to be present on 

the surface (Fig. la). Vibrational bands observed in 0.025 hI KSCN/pcrchlorate 

solution are attributed to a surface film of copper (I) thiocyanate (Fig. lb). The 

band positions are in good agreement with published data on the corresponding 

bulk material but some difference in intensitv is observed. 

100 200 300 400 500 600 100 200 300 400 500 500 

FREQUENCY (cm 'I FREOUENCY (cm ') 

Figure 1. In SZ~U far IR spectra of copper in (a) 0.1 11 NaOH at 0.3 V vs. SCE (ref. 

to spectrum a -1.OV and (b) in 0.025 11 KSCN + 0.1 11 KC10 r at 0.0.5\. vs. SCE 

(ref. to -l.l17). 

IVork supported by the Div. of lIatls. Sci.. BES Off.. CSDOE. Co. To. IV-31-109- 

ENG-38

Infrared Materials for Studying Biological Systems With Infrared 

Microspectroscopy 

L. Miller (AECOM) and L. Carr (NSLS) 

U4IR 

For infrared microspectroscopy, samples such as cells and biological tissues are 

often supported on or between infrared-transparent window materials such as bar- 

ium fluoride (BaFz), potassium bromide (KBr), and zinc selenide (ZnSe). These 

materials have refractive indices that are frequency dependent, so the focal point 

that one sees with visible light through the infrared microscope is different than the 

infrared focal point where the spectrum is taken. In other words, a sample that 

appears focused with visible light is really out of focus to the infrared light, so that 

the sample area chosen for data collection is really larger than it visibly appears. 

The smaller the aperture, the more significant is this focal point "error". Since 

synchrotron infrared microspectroscopy of biological samples involves apertures of 

less than 20 (pm, we find that a focus shift correction must be applied in order to 

obtain spectra with high spatial resolution. Using the frequency-dependence of the 

refractive indices for BaF2, KBr, and ZnSe, we have calculated the expected focus 

shifts for these materials as a function of infrared frequency. Experimentally, we 

have taken infrared spectra on these materials with a range of focus-shifts from the 

visible focal point and we find good agreement with our calculated values. For win- 

dows with a 2 mm thickness, we find differences of = 20, 25, and 60 pm between the 

visible and infrared focal points of BaF2, KBr, and ZnSe, respectively. Therefore, 

after visibly focusing a sample that is mounted on or between the above-mentioned 

materials, the sample must be "defocused by translating the sample stage so that 

the sample is focused for collecting the infrared spectrum. 

Characterization of Bone Mineral Model Compounds Through Far- 

Infrared Spectroscopy 

U4IR 

L.M. Miller, M.R. Chance, Q. He(AECOM), R. Mendelsohn (Rutgers U.), A. 

Boesky (Hosp. Special Surgery), and V. Vairavamurthy (Shoreham-Wading River 

HS) 

Hydroxyapatite, Calo(P04)6(OH)z, is the primary mineral component of bone. 

Bone growth begins as amorphous calcium phosphate crystallizes into hydroxyapatite. 

As the bone matures, the size, crystallinity, and stoichiometry of the hydroxyapatite 

crystals change. For example, the phosphate and hydroxide sites are often 

substituted by other anions such as acid phosphate (HPO;~), carbonate (~0:-), 

and fluoride (F-). The nature of the phosphate environment in bone can be charac- 

terized through analysis of a series of four phosphate bands in the far-infrared region 

(500 - 650 cm-l). The intensities and peak positions of these modes are sensitive to 

the hydroxyapatite crystal size, structure, and stoichiometry. Thus, we have grown 

a series of hydroxyapatite crystals, varying in (1) the initial solution concentration 

of calcium phosphate, (2) the initial solution concentrations of non-stoichiometric 

components such a carbonate and fluoride, and (3) the time of crystal growth. The 

far-infrared spectra of these crystal standards were collected in the form of potas- 

sium bromide pellets. Currently, curve-fitting and integration analysis are being 

used to correlate the peak positions and intensities of these modes as a function of 

the above-mentioned crystal growth parameters. These results will be valuable for 

the interpretation of far-infrared spectra from non-synthetic bone samples.

? 

W 

c3 

Interchain Hydrogen-Bonding Interactions Between the Filaments of 

Actin 

L.M. Miller (AEC0M)and B. Chasan (Boston U.) 

Hydrogen-bonding interactions are crucial to the function of many biological 

molecules. The vibrational modes associated with hydrogen bonds fall in the far- 

infrared region (150-250 cm-'). Actin is the primary component of muscle fibers. 

The single polypeptide unit is known as G-actin. When G-actin polymerizes to 

form actin filaments (i.e. muscle fibers), it is called F-actin. F-actin filaments are 

formed as two G actin monomers are twisted into a helix ancl it is thought that 

they are held together by a network of hydrogen-bonding interactions. Thus, a 

comparison of the far infraretl spectra of G- versus F-actin provides a method for 

stntlying hydrogen-bonding interactions in proteins. IVe have grown films of G- 

and F-actin on polyethylene disks and determined their far infraretl spectra. IVe 

observe 3 modes (532, 544, antl 500 cmp') in both G- and F-actin. In addition, 

we observe intense features in the F-actin spectrum at 181 antl 254 cm-l. which 

are absent in the monomeric G-actin, and may be assignable to hyclrogen bonding 

interactions in the F-actin. We plan to continue our studies on G- and F-actin by 

growing films under different conditions, such as in the presence of D20 antl varying 

salt concentrations. D20 is expected to shift the frequency of hydrogen-bonding 

interactions and various salt conditions provide different levels of polymerization 

of G-actin into F-actin. In addition, the polarized nature of the infraretl light will 

make it possible to study the orientation of the actiri filaments. 

Metal-Ligand Stretching Frequencies in Hemeproteins Through Far- 

U4IR 

Infrared Spectroscopy 

U4IR 

L. hliller (AECORt), T. Sage and P. Champion (Northeastern U.) 

The metal-ligand stretching frequencies in metalloproteins fall in the far-infrared 

region. The iron atom in the hemeprotein, myoglobin, binds four nitrogen ligands 

from the heme group, one nitrogen ligand from a histidine residue in the protein, 

and the sixth coordination position is the oxygen-binding site. Since other ligands 

such as carbon monoxide and nitric oxide also competitively bind to the oxygenbinding 

site, it is important to characterize the structural and electronic intermediates 

that are involved in the ligand-binding process. Since the iron-ligand bond 

can be photolyzed at 10 K. we are able to use photolyzetl/unphotolyzed difference 

FTIR to probe vibrational modes such as (1) the iron-ligand stretching frequency, 

(2) the iron-proximal histicline stretching freqnency, antl (3) heme doming modes, 

all of which differ in the ligand-bound ancl photolyzed states. Resonance Raman 

studies have also been used to identify some of these modes. However, the conditions 

by which several of them are resonance-enhanced are still unclear, making 

infraretl spectroscopy a necessary alternative. In the past, we have been unsuccessfill 

with myoglobin films in polyvinyl alcohol (PVA) on polyethylene clue to (1) the 

temperature-tlepentlence of the far infraretl spectrum of PVA antl (2) the opticallyopaque 

nature of polyethylene, making it tlifficnlt to photolyze rnyoglobin at low 

temperature. Recently, we have shown that solution samples in 75:25 glycero1:water 

(50 prn pathlength) between sapphire windows are reasonably transparent in the 

far infraretl region below 100 K antl cornpletelv transparent in the visible. These 

findings will greatly improve the ability to (I) photolyzc the sample, (2) collect high 

quality difference spectra, antl ( 3) collect far-infrarccl protein spectra in sol~~tion-a 

more biologically relevant st~te of the protein.

Infrared Microspectroscopy of Small Dust Particles of Astrophysical 

Origins* 

U4IR 

- I I 

G. Quitte, J. Borg, L. d'Hendecourt, J.P. Bibring (Inst. d'Astrophysique Spatiale, 

Orsay, France), P. Dumas (LURE and LASIR-CNRS, Orsay, France), G.L. Carr 

and G.P. Williams (NSLS) 

One of the main objectives in studying interplanetary dusts is to qualify their 

physical, chemical, and structural (mineralogical) properties. The ultimate goal is 

to understand the origin and composition of comets and asteroids, which may carry 

information about the origin of the Solar System. Such dust particles have been 

collected from the statosphere or low Earth orbit. Some of these particles are shown 

in Figure I. 

IR microspectroscopy appears to be a useful technique for characterizing the 

chemical composition of these dusts due to its fast and reliable analysis. Here we 

demonstrate how the synchrotron infrared source allows for chemical information 

to be obtained from particles only a micron or two in size (see Figure 2). The 

presence of water, silicates, organics (aliphatics) and an olivine mineral phase have 

been tentatively identified using synchrotron-based spectra. Most of these features 

can not be detected using the conventional (globar) source, due to its low intrinsic 

brightness. 

*Supported by DOE through contract DE-AC02-76CH00016. 

? Figure 1. Optical image of "Orgueil" 

particles. 

W 

Figure 2. Infrared spectra of individual 

" Orgueil" particles, taken with a conven- 

tional source and with the synchrotron 

source. 

Vibrational Dynamics of Cso on Noble Metal Surfaces I U41R 

P.Rudolf ( U.Namur, Belgium), R. Raval ( U.Liverpoo1, England), P. Dumas ( 

LURE and ASIR-CNRS-France), and G.P. Williams (NSLS) 

Previous experiments by infrared spectroscopy on C6o adsorbed on Ag(ll1) sur- 

faces (see Annual report 1994, 1995), carried out at the U4IR beamline, have shown 

that Cso molecules are chemisorbed on the surface, and that the dominant feature 

is for a Ag(2) Raman mode, which becomes IR active upon adsorption. The ap- 

pearance of the Raman active mode was attributed either to a dynamical charge 

transfer from the silver substrate to the Cso, or to a symmetry breaking upon ad- 

sorption. Recent experiments have been carried out on two other surfaces: Au(ll0) 

and Cu(100) in order: I- To follow any charge transfer dependence between these 

surfaces on the frequency of the Ag(2) Raman mode, and 2- To carefully record 

the broadband infrared change on the three surfaces upon Cso chemisorption, and 

to verify if this changes agrees with the diffuse scattering model of the conduction 

electron. 

We have observed a slight frequency change of the Ag(2) mode for C60 on the 

three surfaces (1450 cm-' for Ag(ll1) and Au(ll0) and 1440 cm-' on Cu(100), 

which apparently does not followed the prediction of the charge transfer hypothesis. 

More interestingly, the broadband IR reflectance change is well accounted for by the 

diffuse scattering model (Figs. 1 & 2). According to the friction coefficient model, 

the lifetime of the collective motion of C60, parallel to the surface, and due to 

deexciation via electron-hole pair creation, can be determined from the asymptotic 

limit of the reflectance change. We found values ranging between 170 ps and 220ps 

for Cu, and Au, Ag respectively. Accounting for the Newns-Anderson model, which 

states that the lifetime is proportional to the mass of the adsorbate, and depends 

on the density of states induced by the adsorbed molecule at the Fermi level, the 

value of the lifetime indicates a high density of states induced by the C60 molecules 

upon chemisorption on noble metal surfaces. 

Frequency ( in em.') 

Figure 1. IR spectrum of a monolayer 

of C60 adsorbed on Au(ll0) surface at 

room temperature. The solid line is a fit 

according to the diffuse scattering model 

theory. 

Figure 2. Same as Fig1 , but for Cso ad- 

sorbed on Cu(100) at room temperature.

? 

w 

A I Isotope Effects for the Low Frequency Modes of CO/Cu(100) I U4IR I 

G. P. Williams,( NSLS) and C. J. Hirschmugl, (LBNL) 

In order to fully understand the dynamics and lateral potential energy surface 

of CO molecules chemisorbed onto Cu(100) we undertook a far-IR study of the 

bonding vibrational modes for all the isotopes. The data will be combined into a 

paper which also includes helium atom scattering measurements of the lowest fre- 

quency frustrated translational mode. The figure shows the changes in reflectance 

induced by the CO and fits using an expression of Persson and Volokitin (Sur- 

face Science 310, 314 (1994)) for non-local optics. The data show broadband 

background changes, a dip corresponding to the carbon-metal stretch mode, and a 

peak (anti-absorption) corresponding to the frustrated rotational mode. The Pers- 

son/Volokitin formula takes into account the the background shape and the hindered 

rotation mode. Parameters for the fit are all related to and are close to values for 

bulk Cu and include the Fermi velocity, the plasma frequency, the skin depth and 

the mean free path. The carbon-metal stretch mode was fitted to a Gaussian line 

shape. 

0.992t , , , , , . , , , , 4 

260 280 300 320 340 360 

Frequency (cm-') 

Figure 1. The reflectance ratio of the IRAS spectra obtained with CO to that 

without CO for a ~(2x2) half monolayer (O = 0.5) at 90K. The spectra were obtained 

with a resolution of 0.12me17 and a measurement time of 3 minutes. The 

fits are shown as solid lines. Since the background does not fit well in the vicinity 

of the carbon-metal stretch mode for the ClsO isotopomers. the peaks have been 

displaced. 

I Low Frequency Dynamics for mixtures of S and CO on Cu(100) I U4IR I 

G. P. Williams (NSLS) and C. J. Hirschmugl (U. of Wisconsin) 

To understand the behavior of catalysts better, studies of Sulfur and CO coad- 

sorption systems on metals are required. The adsorption of Sulfur /Cu (100) at 

300K and CO/Sulfur mixtures /Cu(100) at 90K has been studied by Fourier Trans- 

form Infra-red Reflection Absorption Spectroscopy in the 250-2500 cm-1 frequency 

range using synchrotron radiation. The first system is created by exposing Cu(100) 

to various amounts of H2S at 300K. The H2S dissociates, leaving S atoms adsorbed 

at 4-fold hollow sites. Subsequently, the S/Cu(100) substrate is cooled and ex- 

posed to 2L (2x104 torr-s) CO. We have observed a broadband absorption for the 

S/Cu(100) system, as illustrated in Figure 1. The fit to this curve uses the bulk 

parameters that have been found in the past for CO/Cu broadband absorptions[l]. 

The subsequent CO adsorption results in a partial coverage of CO, as confirmed 

by the appearance of the CO stretch at about 2000 cm-l, but the broadband ab- 

sorption and concomitant hindered rotation previously observed for CO adsorbed 

on clean copper are absent. The thermal desorption mass spectroscopy for a 2L 

CO dose on increasing sulfur precoverages indicates a linear decrease in the CO 

adsorbed, which correlates to the intensity (triangles and left hand axis) of the 

CO stretch as shown in Figure 2. The strength of the background absorption for 

CO/S/Cu ratioed to S/Cu spectra, as a function of increasing preatlsorbed S is also 

shown in Figure 2. Notice that the background change tlecreases to zero before 

the CO stretch intensity decreases to zero (corresponding to the spectra in Figure 

1.) Appealing to the Persson-Volokitin motlel that describes the physics which ac- 

counts for the appearance of the hintleretl rotation antl broadband absorption, we 

can attribute the above behavior to the free electrons in the CII scattering primarily 

off of the Sulfur atlsorbatrs, exciting the Sulfur parallel modes. The parallel modes 

of the CO molecules are no longer being driven by this same mechanism. [I] C.J. 

Hirschmugl antl G.P. Williams Physical Review B52 14177 (1995) [2] B.N..T. Persson 

and A.I. Volokitin Surface Science 310 314 (1994) 

09751 . . . ' . ' I 

0 MO two 1MO 2000 

Frequency [cm-'1 

0 W8 

bacngrounacnange 

SICu Auger Ratio 

Figure 1. Figure 1 Figure 2. Figure 2 

0

? 

U1 

I Partial Spectral Weights of Disordered Co-Pd Alloys I U5UA I 

W.J. Kim, J.H. Park, W.G. Park, S.-J. Oh (Seoul National U.), H.J. Kim, 

E.Vescovo (NSLS) 

Recently, considerable interest is given to the interface formation between mag- 

netic and nonmagnetic materials. Therefore the electronic structures of disordered 

Co-Pd alloys were investigated by means of turnable photon energies in the soft 

x-ray region. We made use of the Cooper minimum phenomena of Pd 4d states to 

deduce the partial spectral weights from photoemission spectra. All alloy samples 

were made by arc melting method in the Ar atmosphere. Scraped surfaces were 

cleaned by Ne ion bombardment and anealing at T=400°C in UHV. In order to 

obtain the partial spectral weight of each component the valence band spectra of 

pure metals and alloys are measured in the vicinity of the Cooper minimum. The 

calculated ratio of atomic photoionization cross section between Pd 4d and Co 3d 

is 0.05 at hv=130eV. But this calculated value is expected to change a little due 

to the solid state effects. The difference of lattice constants(9%) should also cause 

some local lattice relaxation and therefore a shift for bonding states and an increase 

in the intensity of antibonding state is expected. It could be related to the strength 

of hybridization. Fig.1 shows valence band spectra of the Co-Pd alloys in different 

at.%-Pd in hv=130eV and the hv-dependence of the photoionization cross section 

in Cos0Pd20. At the Cooper minimum of the Pd-4d cross section (about 130eV) it 

is clearly shown that the intensity of Co 3d emission is the strongest and decreases 

gradually by changing the photon energy. We expect to find out an influence of pho- 

toionization matrix element and take it into account to deduce the accurate partial 

density of state of Pd. The further analysis in detail, whether the theoretically 

purposed model can be successfully applied, is in progress. 

10 5 0 

Binding energy (eV) 

10 5 0 


Figure 1. (a) Valence band spectra of the Co-Pd alloys in hv=130eV and (b) photon 

energy dependence of the photoionization cross section in CosoPdzo. 

Electronic Structures and Magnetic Ordering of Fe0.52A10.48 Alloy 

Films 

I U5UA I 

Y. P. Lee, K. W. Kim, Y. V. Kudryavtsev (Sunmoon U., Korea), G. S. Chang 

(Yonsei U., Korea), E. Vescovo (NSLS), and P. D. Johnson (BNL) 

Equiatomic P-phase FeAl alloy crystallizes into a CsCl (B2) - type structure. 

A perfectly ordered stoichiometric FeAl alloy is not ferromagnetically ordered because 

of an absence of the ferromagnetic nearest neighbors. Even a slight atomic 

disorder can lead to the occurrence of local magnetic moments. It is widely believed 

that these magnetic moments are induced from so-called antistructure Fe 

atoms (Fe-ASA) - Fe atoms at A1 sites. The estimated values for the effective 

magnetic moment of a Fe-ASA spreads widely from 5.4 p~ to 1.5 p ~ and , it is 

clear that there is no common point view yet on the nature and value of the magnetic 

moments of nearly equiatomic FeAl alloys. We investigate the influence of 

the structural order-disorder transition in the nearly equiatomic FeAl alloy film on 

the magnetic moments and electronic structures using spin-polarized photoemission 

spectroscopy at the U5UA undulator beam line of the NSLS. Figure 1 shows the 

spin-polarized photoemission spectra for the ordered and disordered Fe0.52A10.48 

films. The order-disorder transformation enhances the spin polarization doubly in 

an agreement with our magnetic circular dichroism results[l]. By comparing with 

the reported magnetic moment and spin polarization of pure Fe[2], we found the 

spin magnetic moments of the constituent Fe atoms to be 0.25 and 0.55 p~ for the 

ordered and disordered states, respectively. These relatively lower values of the spin 

magnetic " moment also indicate a difference in magnetic structure between the top 

u 

surface layers and the underlying ones. 

1 K. W. Kim et al., J. Appl. Phys. (submitted) 

I1 2 P. D. Johnson et al.. Rev. Sci. Instrum. 63, 1902 (1992) 

ordered state 

.... 

....... 

-spin up \ 

........... spin down 

3 2 1 0 


w 

..... ..' 

spin up 

........... spin down 

3 2 1 0 


Figure 1. Spin-polarized photoemission spectra of the (a) ordered and (b) disordered 

Fe0.5zA10.48 films.

? 

W 

cn I Observation of a Half-Metallic Ferromagnet I U5UA I 

J.-H. Park, E. Vescovo, H.-J. Kim (NSLS), C. Kwon, R. Ramesh, and T. Venkatesan 

(U. Maryland) 

Half-metallic systems are new class of materials which are characterized by the 

coexistence of metallic behavior for one electron spin and insulating behavior for 

the other. The density of states (DOS) has 100% spin polarization at the Fermi 

level (EF), and the conductivity is completely dominated by the metallic single-spin 

charge carriers. This exotic physical properties could have a significant impact on 

technological applications of magnetic devices. 

Here, we have performed spin-resolved photoemission spectroscopy (SRPES) 

measurements on Lao.7Sro.3hIn03 which has been known to exhibit large nega- 

tive magnetoresistance. the so called 'colossal magnetoresistance'. The figure shows 

valence band spin-resolved photoemission spectra near EF measured at (a) T = 

40K and (b) T = 380K. At T = 40K (

On Magnetic Instabilities in FexNil-, Alloys: Spin-polarization 

Measurements of the Valence Bands Structure of Pseudomorphic 

Layers 

F.O. Schumann, R. Zhang, M. Hochstrasser, R.F. Willis (PSU), E. Vescovo, and 

H.-J. Kim (NSLS) 

Recently, it was shown that Fe,Nil-, films can be grown in the fcc phase as 

ultrathin films on Cu(100) [I]. At an Fe concentration of 65% bulk Fe,Nil-, alloys 

the magnetic moment deviates strongly from the Slater-Pauling curve, dropping 

quickly to zero as does the Curie temperature, at which point, a structural phase 

transition from fcc to bcc is observed [2]. Fe,Nil-,/Cu(100) grows pseudomorphically. 

Which 'clamps' the Fe,Nil-, into the fcc phase for Fe concentrations beyond 

65% in these ultrathin layers. In particular, at around ~ ~ 7 alloy 5 % composition, 

the bulk 'Invar Effect' appears to be suppressed in these metastable thin film alloys 

and a new 'low magnetization-density, ferromagnetic phase' is stabilized. 

The phenomenological Stoner band theory of ferromagnetism informs us that the 

exchange-energy splitting of 3d states reflects this change in magnetization density 

and varies linearly with the magnitude of the local magnetic moment of the order 

lev per Bohr magneton [3 . Hence, spin-resolved electron spectra of the valence 

bands in Fe,Nil-,/Cu(100 1 give information on a possible 'low spin magnitude, 

ferromagnetic phase. 

Figure 1 shows a spectrum taken in normal emission with 48 eV light at a concentration 

of ~ ~ 6 and 0 % Figure 2 a spectrum at a concentration of ~~75%. The 

copper d-band of the substrate is clearly resolved at around 3 eV below the valence 

band edge. Also, large changes in the density of states of the alloy valence bands are 

observed as a function of changing stoichiometry, together with their spin- resolved 

states. Work is in progress to get more insight into the underlying physics of the 

electronic structure. 

1. F. Schumann et al, Phys. Rev. B, 56, 2668 (1997). 

2. E.F. Wassermann, J. Magn. Magn. Mater., 100, 346 (1991). 

3. F. Himpsel, phys.' Rev. cett., 65, 2363 (1992). 

Elemon Energy lev 

? Figure 1. Spin-resolved spectra of an 

FesoNiso alloy. 

-a 

39.5 40 10.9 U 41.5 &2 145 U 

Eledmn Energy lev 

Figure 2. Spin-resolved spectra of an 

Fe75Ni25 alloy 

I Spin Resolved Photoemission Study of Magnetite I U5UA I 

E. Vescovo, H.-J.Kim, J.-H. Park (NSLS), H.S. Choi, and T.W. Noh (Seoul National 

u.1 

Magnetite - Fe304 - is one of the most studied oxides because of its mangetic 

and electric properties. At variance with the majority of the oxides - which are 

antiferromagnetic - Fez04 is a ferrimagnet (TN = 858 K). Its crystal structure is a 

spinel structure in which the large oxygen atoms form a close packed fcc lattice with 

the smaller Fe atoms occupying two inequivalent interstitial positions: tetrahedral 

A-sites and octahedral B-sites. The A-sites accomodate Fe3+ ions while the B-sites 

contain a mixture of Fe3+ and ~e~~ ions. The ferrimagnetism is explained assuming 

that the A and B sublattices are both ferromagnetic but antiparallel oriented 

with respect to each other: the magnetic moments of the Fe3+ ions compensating 

each other, while the macroscopic magnetization being supported by the unpaired 

Fe2+ ions. Much of the interest in magnetite is connected to its peculiar matalinsulator-like 

Verwey transition. This is a first-order transition characterized by 

an abrupt decrease of the conductivity by two order of magnitude below the Verwey 

temperature of about 120 K. Obviously valuable informations on the electronic 

structure can be obtained by spin-resolved photoemission experiments. Due to the 

high surface sensitivity of this technique, it is mandatory to prepare the surface 

in-situ. We started from an Fe304 thin film (about 1000 A thick) epitaxially grown 

on an MgO(001) substrate by Pulsed Laser Deposition technique and obtained a 

magnetic and ordered surface by repeted annealing cycles in oxygen atmosphere. 

The spin-resolved photoemission spectrum from this film taken at 36eV photon energy 

is shown in Fig.1. Fig.2 shows the spin polarization. Tentatively the minority 

feature at 0.5 eV below Ef can be attributed to the t2, state of the ~ e in ~ the + 

B-site; the majority feature at about 1.8 eV binding energy should originate from 

the Fe3+ in the B-site (e, state); and finally the minority peak at about 2.9 eV 

should derive from the antiparallel Fe3+ in the A-site. 

- 

--$PI" up 

-spin dawn 

1 4 1 2 1 0 8 6 4 2 0 

Blnding Energy (eV) 

Figure 1. 

1 4 1 2 1 0 8 6 4 2 0 

Blndlng Energy (eV) 

Figure 2.

? 

W 

03 1 The Magnetic Structure of Strained Thin Films of Gadolinium I U5UA I 

C. Waldfried (U. of Nebraska) 

The electronic structure of strained thin films of Gd has been studied with spin 

and angle resolved photoemission. The spin temperature dependent electronic structure 

is dominated by an admixture of Stoner-like and rigid band magnetism. A very 

distinct thickness and k-dependence of the exchange splitting can be correlated to 

electron localization and the band structure. The surface magnetic structure is observed 

to be different from that of the bulk, as indicated by the clifferent electronic 

structure and a much higher surface Curie temperature. approximately 10% over 

the strained bulk. The 4% strain within the Gd films results in an enhanced Curie 

temperature as compared to the relatively unstrained Gtl(0001) by approximately 

50 K (a T(C) in excess of 340 K) and a very clifferent electronic structure. iVith 

decreasing thickness the bulk bands of the strained Gd films exhibit increasingly 

more paramagnetic-like behavior over an increasing volume of the Brillouin zone. 

The surface magnetic structure clo~ninates the magnetic ordering of the ultra-thin 

Gtl films. 

Characterization of Pure and Sulfided NiMo04 Catalysts using Syn- 

chrotron based X-ray Absorption Spectroscopy (XAS) and Tempera- 

ture Programmed Reduction (TPR) 

S. Chaturvedi, J.A. Rodriguez (BNL) and J.L. Brito (IVIC) 

U7A 

This study aims to characterize the properties of pure and sulfided Nib1004 cata- 

lysts using synchrotron based near edge x-ray absorption fine structure (NEXAFS) 

and temperature programed reduction (TPR). hlo 31111-edge NEXAFS spectra in- 

dicate that on reaction with HzS, the i\Io component of NihIoO,r gets partially 

reduced with the formation of hloS2 type species. For the beta phase of NihIo04, 

the sulfidation of hIo is more extensive thau for the alfa-phase, rnaking the former 

a better precursor for catalysts of hyclrodesulfurization (HDS) reactions. The Ni 

LII-edge features are relatively insensitive to the changes accompanying the partial 

sulfitlation of NihIo04. The sulfitlation of the Ni component is confirnletl by anal- 

ysis of the Ni K-edge extended x-ray absorption fine structure (EXAFS) spectra 

which show the formation of Ni-S bonds (bond length 2.48 ) and a NiXIoSx phase. 

The S K-edge NEXAFS spectra show the presence of at least two types of sulfur 

species, one associated with a formal oxidation state of -2 and another associated 

with a formal oxiclation state of +G. IVe attribute the former to the presence of 

metal-sulfur bonds (hZoS, antl NiS,). The latter is associated with the formatiou 

of S-0 bonds (s0a2-). The formation of sulfates is also supported by the 0 I

Reaction of Sz with ZnO and Cu/ZnO Surfaces: Photoemission and 

Molecular Orbital Studies 

S. Chaturvedi, J.A. Rodriguez and J. Hrbek (BNL) 

U7A 

The adsorption of S2 on ZnO and Cu/ZnO has been investigated using 

synchrotron- based high-resolution photoemission spectroscopy. On dosing a clean 

ZnO surface with Sg at 300 K, the molecule dissociates. The S is associated first 

with Zn and at medium coverages with Zn-0 sites. When the sulfur coverage is 

increased to S= 0.5 ML, evidence is found for sulfur bound purely to the 0 sites 

of ZnO. The sulfur species associated with 0 and the Zn-0 sites are unstable at 

temperatures above 500 K. Possible reaction pathways for the dissociation of S2 on 

ZnO(0001)-Zn and Zn(l0 0) surfaces were studied using ab initio SCF calculations. 

At low sulfur coverages, an adsorption complex in which Sg is bridge bonded to two 

adjacent Zn atoms (Zn-S-S-Zn) is probably the precursor state for the dissociation 

for the molecule. It is possible to get much higher coverages of sulfur on ZnO (0.7 

ML) than on A12 O3 (0.1 ML) at similar Sz exposures. This, in conjunction with 

results previously reported for Hz S adsorption on Crg 03 and Cr304, indicates 

that the reactivity of metal oxides towards sulfur is inversely proportional to the 

size of their band gap. Oxides with a large band gap (e.g. A12 03 9.0 eV) are 

less susceptible to sulfur adsorption than oxides with a small band gap (e.g. ZnO 

3.4 eV). The presence of Cu atoms on both metal oxides enhances their respective 

reactivities towards Sg. Upon dosing Cu/ZnO with Sg at 300 K, sulfur prefers to 

attack supported Cu followed by reaction with the Zn sites of the oxide, and at large 

sulfur coverages the adsorbate bonds simultaneously to metal and oxygen sites on 

the surface. The sulfur bonded to both the metal and oxygen sites on the surface 

is relatively weakly bound and desorbs by 500 K. The Cu-S interactions are strong 

and lead to the formation of copper sulfides that exhibit a distinctive band structure 

and decompose at temperatures above 700 K. 

Chemistry / Orientation of Lubricants on Hard Disk Magnetic Media 

Substrates Using Near Edge X-ray Absorption Fine Structure 

U7A 

B. M. DeKoven (Dow), D.A. Fischer (NIST), G E. Potter, T. Richardson, D. J. 

Perettie (Dow), Singh Bhatia (IBM), T. A. Morgan, (Dow), and S. Hsu (NIST) 

In this study we describe the interactions of a lubricant system with carbon over- 

coat surface typical of a magnetic hard disk. The lubricants used are cyclophos- 

phasene (X-1P) and Fomblin (ZDOL). The following system parameters were stud- 

ied: effects of surface burnishing; ZDOL alone, X-1P alone, ZDOL/X-1P mixtures, 

and carbon overcoats (7.5 nm) with varying hydrogen contents (using Ar and Ar / 

H2 treatments). 

Near Edge X-ray Absorption Fine Structure (NEXAFS) was used to probe the 

reactivity and orientation of applied lubricants on the surface of the various (16) 

lubricant disk systems combinations. NEXAFS is an ideal non destructive tool 

for studying the disk lubricant system since it has both elemental and chemically 

sensitivity, with great selectivity in bond type. The technique can also make direct 

comparisons between the surface and bulk by measuring simultaneous electron yield 

(5 nm depth sensitivity) and fluorescence yield (200 nm) spectra. In addition, 

the average orientation of chemical bonds may be measured via the polarization 

anisotropy of the soft x-ray absorption spectra. NEXAFS spectra above the Co and 

Ni L edges as well as C, 0, F K edges were recorded. Orientation of the lubricants, 

thickness, and morphology of the carbon hardcoat and magnetic media are discussed 

in detail for the samples listed above. 

The NEXAFS results suggest little specific orientation of lubricant molecules on 

COCs, with the exception of X-lP, and only before burnishing. Apparent surface 

vs. bulk content of Ni may be consistent with the presence of 'cracks' in the COC 

overlayer or corrosion phenomena. Also, Co appears to be present in the surface 

region (top 5 nm), unlike Ni. This also suggests cracks or corrosion in the COC 

overlayer system. For the COC produced without hydrogen we see a systematic 

reduction in Co upon lubricant application and further reduction upon burnishing.

? 

A 

3 

C-N Bond Activation of Cyclohexylamine on the Ni(100) Surface U7A 

A.M. Gabelnick, S.hL Kane, A.T. Capitano (U. of Michigan), D. A. Fischer (NIST), 

and J.L. Gland (U. of Michigan) 

The effect of hydrogen on carbon-nitrogen bond activation has been studied with 

cyclohexylamine (CHA) on the Ni(100) surface as a part of continuing research on 

C-N bond activation on metal surfaces in vacuum and high pressures. Hydrogen 

has been shown to have a very important role in a wide variety of bond activation 

processes. Carbon-nitrogen bond activation and the role of hydrogen was stud- 

ied for CHA on the Ni(100) surface in pressures of hydrogen from vacuum up to 

0.02 torr. Temperature Programmed Fluorescence Yield Near Edge Spectroscopy 

(TP-FYNES) allowed for the determination of surface carbon concentration as the 

reaction progressed, while Fluorescence Yield Near Edge Spectroscopy (FYNES) 

anneal sets were used to determine the nature of the surface intermediates. 

Using FYNES, the intermediate for C-N bontl activation of CHA on the Ni(100) 

surface was determined to consist of a partially dehydrogenated cyclohexyl ring ad- 

sorbed nearly parallel to the surface, as indicated by an increase in the .ir* resonance 

at bontl activation temperatures using normal incidence synchrotron radiation. TP- 

FYNES experiments taken in 0.02 torr of hydrogen showed a decrease in surface 

carbon at 220K relative to similar experiments in vacuum. This is indicative of a 

slightly more facile C-N bontl activation process caused by high pressures of hyclro- 

gen. 

Examination of Ordering in Self Assembled hlonolayers and Adsorbed 

I Protein Films with Near Edge X-ray Absorption Fine Structure * I U7A I 

L. Gamble, D. Castner (U. of Washington), D. Fischer (NIST), P. Stayton, and K. 

Nelson (U. of Washington) 

For many bio-engineered materials the molecules involved in surface modification, 

such as self-assembled monolayers (SAh'Is) or proteins, need to be oriented 

in a specific direction. For example, it may be necessary for functional groups to 

point away from the surface or proteins may require active sites facing away from 

the substrate to allow for enhanced reactivity. The orientations of functionalized 

alkane thiols on gold and adsorbed proteins on alkane thiols have been studied by 

near edge x-ray absorption fine structure (NEXAFS). Self-assembled monolayers 

were prepared from biotinylatecl alkane thiol (BAT), which is an alkane chain with 

a biotin head group, as well as from methyltiexadecantl thiol (LIHD). Mixed monolavers 

of BAT and RIHD thiols were also prepared. NEXAFS spectra indicates that 

SAhIs made from mixed BAT-alkane thiol solutions are more highly ordered than 

those made from 100% BAT solutions. NEXAFS spectra (taken in the partial electron 

yield mode) of SAhIs prepared from a solution of 40% BAT and 60% RIHD 

show strong polarization clepericlence in the C-H* and C-C* resonance. NEXAFS, 

aided by XPS data, indicates that the RIHD "tlilntant" helps to order the alkane 

chain of the B.AT to starid relatively perpendicular to the surface, thus orienting 

the biotin headgroup away from the substrate. iVhen the protein streptavitlin (SA) 

is atlsorbctl on a XIHD monolaver, a small amount of polarization dependence is 

seen at the N K-edge. Further research inclutles study of different protein struct~~rcs 

on goltl and "rubbed" PTFE on goltl surfaces. SAhIs made with different 

f~~nctiorializecl alkane thiols and Huorinatetl thiols are being stlldied as well. 

* This work was supported%y University of \Vashington Engineered Biomaterials (XSF 

EEC-9529161) and SES=\C/BIO (SIH RR01296)

Photoemission of Cleaved and "As-Grown" Surfaces of Pyrite 

S 2p photoemission on the U7a beamline has been used to investigate the surface 

composition and stoichiometry of pyrite, FeS2. Two types of surfaces have been 

investigated; surface produced by cleavage of a single crystal sample of pyrite and 

an "as-grown" surface [striated (loo)] face, bombarded in UHV with ~ e to + remove 

residual carbon and oxygen contamination. Both surfaces have been annealed to 573 

K prior to study. Comparison of these two samples is partly motivated by the need 

to determine the differences in structure that result when preparing geochemical 

surfaces for study in UHV. The latter preparation method provides a way to create 

a reproducible surface that can be then used for surface reactivity studies. Figure 

1 exhibits typical S 2p data for the two surfaces. For each surface it is proposed 

that 4 different S 2p species (denoted by A, B, C, and D doublets) contribute to 

each spectrum. Contributions A and B are thought to be due to S in the outermost 

surface region. We tentatively believe that A is, at least due in part, to monosulfide, 

FeS, and B is due to pyrite S (stoichiometry of FeS2) that is shifted from the bulk S 

contribution (i.e., feature C). Finally, feature D is probably due to a more reduced 

form of S, perhaps similar to polysulfide (this has been proposed to exist on pyrite 

by other research groups). Assignments for A, B, and C have been independently 

supported by additional experiments. For example, experiments at U7a have shown 

that the decomposition of H2S on pyrite significantly reduces feature A, consistent 

with the conversion of a monosulfide species into the disulfide that characterizes 

pyrite. Furthermore, S 2p data obtained with conventional XPS (using 1253 eV 

radiation) shows only a small contribution from A and B, consistent with these 

features being due to surface S species. Comparison of the two samples suggests 

that cleavage results in a more sulfur deficient surface. The surface prepared by 

gentle ion bombardment results in a more S-rich surface that may be closer to a 

natural surface then is the surface created by cleavage. Future experiments are 

planned that will help confirm many of the tentative assignments made here. 

-170 tea -,m .iY iS2 ->m -3s 


U7A 

J. Guevremont (Temple U.), M.A.A. Schoonen (SUNY-Stony Brook), D. Strongin 

(Temple U.), and M. Strongin (BNL) 

? Figure 1. S 2p photoemission of an "as-grown" and cleaved sample of pyrite, FeS2. 

5 

Surfaces of Semifluorinated Block Copolymers Studied Using NEX- 

U7A 

--- A PS - I I 

E. J. Kramer, J. Genzer (UCSB), J. Wang, H. Korner, C.K. Ober (Cornell University), 

B.M. DeKoven, R.A. Bubeck (Dow Chemical Co.), D.A. Fischer (NIST) 

We synthesized styrene-isoprene diblock copolymers in which the isoprene block 

was modified by attaching semifluorinated (-CO-(CH2),-(CF2),F) side groups. Re- 

cent X-ray diffraction measurements demonstrated that these semifluorinated di- 

block copolymers (SFDs) form highly ordered liquid crystalline (LC) structures 

whose morphologies are dictated by the combination of x and y. In addition, con- 

tact angle measurements revealed that surfaces of thin films made of these SFDs 

exhibit extremely low surface energies indicating the presence and high ordering of 

-(CF2),F blocks at the surface. In the present study, near-edge X-ray absorption 

fine-structure (NEXAFS) is used to examine the structure of thin SFD films on a 

molecular level. By simultaneously detecting both the electron yield (EY) and the 

fluorescence yield signals whose probing depths are ca. 2 and 100 nm, respectively, 

both the near-surface and "bulk" structures of the SFDs are studied. The use of the 

EY signal is particularly advantageous because it allows us to examine the molec- 

ular orientation within the LC phase and its role on the surface organization of 

thin films SFDs. Changes in the molecular orientations within the semifluorinated 

side groups of the SFDs as revealed from the NEXAFS measurements on samples 

annealed in-situ at various temperatures can be correlated with the organization 

changes (smectic-B - smectic-A - isotropic) previously detected with differential 

scanning calorimetry.

? 

A 

N Hole State Density and Superconductivity in Ca-substituted Yttrium 

I Direct Observation of the Complete Rehybridization of the Carbon 1 I 

Barium Copper Oxide (Y-1:2:3) 

A. R. Moodenbaugh (BNL) and D. A. Fischer (NIST) 

U7A 

Oxygen K near-edge spectra obtained using fluorescence yield from x- 

ray absorption were recorded for polycrystalline YBa~Cu307 (Ca-1:2:3) and 

(Yo.ssCao.l~)Ba~Cu307 (Y-1:2:3). As oxygen content is increase from x=6.12 in 

Ca-1:2:3, the superconducting transition temperature rises, reaches a maximum of 

80K near x=6.8, then falls at higher oxygen contents. The near edge structure 

identified with hole density (energy E=529 eV) increases throughout the range of 

oxygen content. Two additional pre-peaks are observed near 530 and 531 eV, both 

with maximum intensity at minimum oxygen content, and having similar intensities. 

Similar peaks are observed for Y-1:2:3. 

Carbon Double Bond in Chemisorbed Propylene on Supported Silver 

Materials Using NEXAFS 

U7A 

J.T. Ranney, D.A. Fischer (NIST), D.H. Parker, R.G. Bowman (Dow Chemical), 

and J.L. Gland (U. of Michigan) 

The room-temperature chemisorption and near-complete rehybridization of 

propylene on dispersed silver supported on Ti02 (anatase) has been observed for 

the first time on a supported material. The thermal chemistry of adsorbed propy- 

lene has been characterized on Ag/TiOz using fluorescence yield Near-Edge X-ray 

Absorption Fine Structure (NEXAFS) at the carbon K edges. The intensity of 

the propylene C 1s to pi* resonance at the carbon K edge is nearly extinguished 

upon chemisorption of propylene on the material at 300 K. The loss of the pi* res- 

onance indicates substantial rehybridization of the C-C double bond resulting in 

a reversibly adsorbed di-sigma bonded surface species. When adsorbed at liquid 

nitrogen temperatures both adsorbed and condensed propylene retain their pi char- 

acter. No propylene adsorption is seen on the neat Ti02 support even at 115 K 

and propylene does not adsorb on silver single crystals above 200 K. Therefore, we 

propose that the room temperature adsorbed propylene may be related to areas of 

strong interaction such as the perimeter of the silver particles. 

This is the first direct observation of chemisorbed reactant monolayers on a sup 

ported materials using fluorescence yield carbon K-edge NEXAFS. These exper- 

iments demonstrate an exciting new technique for observing and characterizing 

adsorbates on supported materials. This technique is element specific and probes 

the bonding and concentration of the adsorbed species independent of the optical 

properties of the sample. We have demonstrated that carbon-edge NEXAFS is an 

ideal technique for the direct characterization of adsorbed reactants, even on porous 

complex materials.

I Tribochemical Reactions of Nanometer Lubricant Films I U ~ I A 

Z.F. Yin, S.M. Hsu, D. A. Fischer, X. Zhang and J. Zhang (NIST) 

Several lubricants were deposited on Cu, and 52100 steel surfaces by modified 

dip-coating method to form nanometer scale films. The lubricants chosen for this 

study were stearic acid and some other simple organic compounds. The films were 

characterized by using reflectance FTIR spectroscopy and ultra soft x-ray absorp- 

tion spectroscopy (USXAS). A well designed multi-tips scratcher was employed to 

execute the tribological treatment. The treatment was done in a very slow motion 

in order to minimize the effects of flashing heat. For comparison, another set of 

duplicated samples deposited in the same way were heated in a furnace to induce 

the thermal reaction. It was found that the tribochemical reaction and thermal 

reaction between stearic acid and Cu substrate were similar. The chemical change 

can be detected by reflectance FTIR and USXAS spectroscopies. The results will 

be discussed and compared with previous works. Tribochemical reactions of other 

films will also be reported and discussed. 

I Partial Densities of States in Cu-Pd alloys I U ~B I 

S.L. Qiu, Yang Li and R.G. Jordan (Florida Atlantic University) 

We have carried out a series of photoemission measurements from polycrystalline 

samples of ordered C U ~ ~ Cu75Pd25 P ~ ~ (with ~ , L12 structure) and ordered Cu58Pd42, 

CusoPdso (with CsCl structure) over the photon energy range 40 - 140 eV. Our 

aim is to determine the Cu- and Pd- contributions to the density of states by 

exploiting the Cooper minimum in the Pd 4d photoemission cross-section at about 

130 eV. In addition, we have also made preliminary investigations on the core level 

shifts and line-shapes in order to probe the local Cu and Pd environments in these 

alloys. We show in figure 1 a selection of valence-band spectra from CuPd, and in 

figure 2 the densities of states of Cu and Pd calculated using the SCF-LMTO-ASA 

method. Relativistic x-ray photocurrent calculations using the potential functions 

and density of states from an electronic structure calculation based on the RKKR 

method are under way for an appropriate comparison with the experimental results. 

-12 -10 -8 -5 -4 -2 0 2 


Figure 1. Selection of valence-band pho- 

toemission spectra from a polycrystal 

temperature. 

- 4 - 2 0 2 4 6 8 1 0 

Energy W) 

Figure 2. Density of states in Cu and 

Pd calculated using SCF-LMTO-ASA 

method.

? +P 

+ I Photon-Stimulated Desorption of Ot from Zirconium Oxide * I U ~ I A 

W.C. Simpson and T.M. Orlando (PNNL-EMSL), W.K. Wang and J.A. Yarmoff 

(U.C. Riverside-Physics) 

Zirconium-based alloys are commonly used as cladding for nuclear fuel rods and 

in various components in nuclear power plants, primarily because of the robust na- 

ture of the oxide that forms. which is highly resistant to corrosion. Yet, zirconium 

oxide films break down when submitted to the extreme radiation conditions present 

in a nuclear reactor. It has been suggested that low-energy electronic excitations 

generated in the material by the ionizing radiation lead to its degradation, but the 

exact nlechanism is unknown. We are currently conducting a set of controlled ex- 

periments to investigate the role of low-energy excitations in the radiation darnage 

of zirconium oxide. Our approach is to take a well-characterized ZrOz surface and 

submit it to bornbarclment by a monochromatic beam of low-energy photons. hIea- 

swements of the 0+ desorption threshold antl kinetic energy distribution, coupled 

with photoemission measurements of the electronic structure of the surface, en- 

able the identification of the excitations that result in oxygen removal from a ZrOa 

surface. For both crystalline and amorphous ZrOz. the Of photon-stimulated des- 

orption thresholtls are at 30 eV, corresponding to the removal of a Zr(4p) electron, 

and the ions have 2 eV of kinetic energy. These findings are consistent with the 

Knotek-Feibelrnan mechanism for stinlulatetl ion tlesorption from metal oxides, in 

which the ionization of a shallow metal cation core level, follow~tl by interatomic 

Auger decay, leads to the formation antl rapid ejection of Of ions from the surface. 

20 30 40 50 60 70 80 90 100 

Photon Enerav IeV) 

-. . , 

Figure 1. The 0' PSD threshold for cubic zirconia and osiclizecl zirconium foil. 

This work was supported by L3 DOE. Div. Chem. Sci.. BES. 

1 Photoemission Studies of the Chemisorption of Chlorine on InAs(001) I UgA I 

W.K. Wang (U.of California, Riverside and LBNL), W.C. Simpson (EhISL, PNNL) 

and J.A. Yarmoff (U.of California, Riverside and LBNL) 

Reaction of halogens and halogen-containing compounds with 111-V semiconductor 

surfaces are of considerable importance since they play a major role in the 

fabrication of optoelectronic devices. Previous studies mainly concentrated on the 

reaction of chlorine with GaAs [I]. It was shown that Clz spontaneously etches 

GaAs at room temperature under conditions which depend on the initial surface 

stoichiometry and order. In the present work, we focus on the interaction of Cla 

with InAs in order to understand the role of surface structure and stoichiometry for 

this system. 

The reactions of Clz with In- and As-terminated InAs(001) surfaces in UHV were 

investigated with synchrotron-based soft x-ray photoelectron spectroscopy (SXPS) 

and low energy electron diffraction. An In-terminated InAs(001)-c(8x 2) surface was 

prepared by Ar' ion bombardment ancl annealing. An As-terminated InAs(001)- 

~(2x8) surface was obtained by adsorbing I1 on the ~(8x2) surface arid then removing 

In iotlides by heating [2]. Chlorinc was produced from a UHV compatible 

solitl-state electrochenlical cell. 

High-resolution core-level spectra were collected from the clean antl chloririatetl 

surfaces. Representative spectra are given in Fig. 1, which indicate that Clz tlissociatively 

atlsorbs, breaking the In-As bonds in a similar manner as with GaAs. The 

stoichiometry of the near- surface region tletcrmines the relative amount of surface 

reaction protllicts. The bond breaking s~~ggests that the spontaneous reaction itself 

is a preh~tle to etching. 

I . 1V.C. Simpson and J.A. Yarmoff, Ann. Rev. Phys. Chern. 49, 527 (1996) 

12 1 . P.R. lJarckamp. A1.C. Hakar~sson, d. Kanski, D.K. Shuh, hI. qjorkqvist, hl. 

Cothelid, W.C. Simpson, U.O. Karlsson autl .J.A. Yarrnoff, Phys. Rev. B 54, 2101 

(1996) 

Figure 1. High-resolution In -ld and As 3cl core-level spectra collected after a 200 

p-Ismin exposure of Cla shoxvn along with numerical fits to the data. The dots 

show raw data after background subtraction. The dashed lines are the individual 

components. while the solid line is the sum of the components.

Chloroethane Physisorbed on Hydrogenated Si(ll1): A Test System 

U8B 

for the Evaluation of Core-Level XPS Assignment Rules * 

1 Photoemission Assignments of H,SiO4-, 

- 

I Interface * 

Fragments at the Si/SiO, 1 U~B 1 

F.R. McFeely (IBM), K.Z. Zhang and M.M. Banaszak-Holl (U. of Michigan) 

S. Lee and M. M. Banaszak Holl (Brown U.), W. H. Hung and F. R. McFeely 

Evidence for Second-Neighbor effects in photoemission on silicon surfaces was 

presented. The chloroethane molecule, known to exhibit second neighbor effects in 

the gas phase C 1s spectrum, was physorbed onto a Si(ll1) surface. No reduction in 

binding energy shift difference was observed, suggesting that the highly polarizable 

silicon surface does not cause a diminuition of second-neighbor effects upon binding 

energies. For a complete description of this study see: Mat. Res. Soc. Symp. Proc. 

446, 15 (1997). 

60 62 64 66 68 70 

PHOTOELECTRON KINETIC ENERGY (8V) 

Figure 1. Least-squares fit of the C 1s spectrum of physisorbed chloroethane, illustrating 

resolution into two components. 

? @ 

rn * This work was supported by NSF Grant No. DMR-9596208 and IBM. 

Hydrogenation of the silicon/silicon oxide interface is shown to cause changes in 

every interface feature spectroscopically discernable by soft x-ray photoemission in 

additional to depinning the Fermi level. A new feature is observed to grown in at 

3.6 eV with respect to bulk Si upon exposure to atomic hydrogen at the expense 

of interface states intermediate between 0 and 3.6 eV. For a full discussion of this 

work see: it. Phys. Lett. 68, 1081 (1996). 

3 

I 

0 

V 

"." 

5.5 4.5 3.5 2.5 1.5 0.5 

BIWG tLRW SHlFl (relolii lo bulk Si Zp3p cY] 

0.05 

0.00 -4 -2 0 2 4 

BINDING ENERGY (retolive b 0 1s maxirmun, rV) 

Figure 1. Top: soft x-ray photoemission (Si 2p3/2 core-levels, 170 eV photon en- 

ergy) thermal oxide(1, line), 5 min hydrogen radical exposure (11, crosses), 20 (111, 

triangles), and 670 C anneal (IV, circles). 

* This work was supported by NSF grant No. DMR-9596208 and IBM.

? 

rP 

rn 

Si 2p Core-level Shifts at the Si(100)-Si02 Interface: An Experimental 

U8B 

Study * 

I I I 

K. Z. Zhang, M. RII. Banaszak Holl (U. of Michigan), J. E. Bender, S. Lee (Brown 

U.), and F. R. lLIcFeely (IBM) 

Si 2p core-level shifts were measured for a model system generated from 

HSi(OCH2CH2)3N and Si(100)-2x1 (Fig. 1) and compared to the result obtained 

from a species containing similar coordination about silicon, HSi(OCH3)s. The 

dramatic difference in the products obtained was explained in terms of the chelate 

effect. The results were compared to previous results obtained using spherosilox- 

ane clusters and an empirical, model-compound based core-level shift assignment 

scheme was compared and contrasted with the conventional formal oxiclation state 

assignment scheme. For a full discussion of this work see: Phys. Rev. B 54, 7686 

(1996). 

0.5 

I I I , I 

60 62 64 66 68 70 

PHOTORECTRON KINETK: ENERGY, eV 

BINDING ENmGl [with respect to bulk Si 2p3h, eV] 

Figure 1. (a) Raw Si 2p core-level spectrum of the silatrane cluster. bound to 

Si(100). (b) Si 2p3/, core-level component peaks. 

* This work was supported by XSF Grant No. DSIR-9596208 and IBSI. 

A New Model Silicon/Silicon Oxide Interface Synthesized from 

HloSiloOls and Si (100)-2x1 * I I 

K. Z. Zhang, L. M. RiIeeuwenberg, M. M. Banaszak Holl (University of Michigan), 

F. R. McFeely (IBM) 

A model silicon/silicon oxide interface, synthesized from the spherosiloxane 

HloSiloOlj and Si(100)-2x1, was characterized by study of the Si 2p core-levels 

and valence band region using soft X-ray photoemission. In addition, the intact 

HloSiloO15 cluster was condensed at -160 C onto Si(ll1)-H and characterized. The 

measured photoemission features are in good agreement with the results of previous 

model studies. These experiments suggest that the formal oxidation state assign- 

ment scheme typically applied to the interpretation of Si 2p core-level spectroscopy 

of Si/Si02 interfaces is overly simplistic. For a full discussion of this work see: Jpn. 

J. Appl. Phys. 36. 1622 (1997). 

Figure 1. Two views of HloSiloOlj high- 

lighting the 2 ten-membered rings and 

the 5 eight-membered rings. 

* This work was supported by YSF grant 

No. DSIR-9596208 and IBSI. 

Figure 2. HloSiloOlj chemisorbed on 

Si(100)-2x1 at 25 C. Panel =\:Si 2p3,12 

core-levels. Panel B:valence band.

Soft X-ray Si 2p Core-level Spectra of HsSi8Ol2 Physisorbed on 

Si(ll1)-H: Additional Experimental Evidence Regarding the Binding 

Energy Shift of the HSi03 Fragment * 

K. Z. Zhang and M M. Banaszak Holl (U. of Michigan), F. R. McFeely (IBM) 

U8B 

The hydridospherosiloxane cluster H8Si8012 was physisorbed onto Si(ll1)-H and 

soft X-ray Si 2p core-level spectra obtained. The results confirmed that HSi03 units 

are observed at roughly -3.6 eV binding energy for the intact cluster. Fragments 

of this type are of considerable interest because of the role of hydrogen in device 

failure. For a detailed discussion of these ex~eriments and references see: Mat. Res. 

SOC. Symp. Proc. 446, 241 (1997). 

3 

-5 -4 -3 -2 -1 0 1 2 

Blndlng Energy (eV) 

-16.0 -12.0 .to -4.0 0 


hu = 170 eV 

Figure 1. Soft X-ray photoemission spectra of the physisorbtion of H8Si8012 onto 

Si(ll1)-H at -140 C. Panel A: Si 2p3/2 core-levels. Panel B: valence band. 

? A 

-J * This work was supported by NSF Grant No. DMR-9596208 and IBM. 

The Role of Extra-Atomic Relaxation in Determining Si 2p Binding 

Energy Shifts at Silicon/Silicon Oxide Interfaces * 

U8B 

K.Z. Zhang, J. N. Greeley, M.M. Banaszak Holl (University of Michigan), F. R. 

McFeely (IBM) 

The observed binding energy shift for silicon oxide films grown on crystalline 

silicon varies as a function of film thickness. The physical basis of this shift has 

previously been ascribed to a variety of initial state effects (Si-0 ring size, strain, sto- 

ichiometry, and crystallinity), final state effects (a variety of screening mechanisms), 

and extrinsic effects (charging). By constructing a structurally homogeneous silicon 

oxide film on silicon, initial state effects have been minimized and the magnitude 

of final state stabilization as a function of film thickness was directly measured. 

In addition, questions regarding the charging of thin silicon oxide films on silicon 

were addressed. From these studies, it is concluded that initial state effects play a 

negligible role in the thickness-dependent binding energy shift. For the first 30 of 

oxide film, the thickness-dependent binding energy shift can be attributed to final 

state effects in the form of image charge induced stabilization. Beyond about 30 , 

charging of the film occurs. For a detailed discussion of this research see: J. Appl. 

Phys. 82, 2298 (1997). 

Binding Energy (eV) I Blndlng Energy lev) 

Figure 1. Soft X-ray photoemission spectra of H8Si8OI2 derived films varying in 

thickness from 0.6 to 7 nm. Panel (a): valence band spectra.Pane1 (b): Si 2p3/, 

core-level spectra. 

* This work was supported by NSF grant No. DMR-9596208 and IBM.

? 

A 

co I Fluorescence of Paper Filters I U ~ B 

I 

R. h'Iantauffe (Pall Corporation) and J. Sutherland (BNL- Biology) 

The time resolved fluorescence and scattering of UV light from several types of 

filters with a variety of uses in research and industrial applications mas recorded 

using the Fluorescence Omnilyzer detector. In certain applications, such as the 

investigation of the composition of aersol samples by fluorescence spectroscopy, it 

is extremely desirable to have the filter contribute as little fluorescence as possible. 

Studies of several commercially available filters as well as non-production test 

samples revealed that some clemo~lstrated considerable fluorescence, while others 

showed only low levels of fluorescence. albeit detectable levels. Polarization stndies 

showed that fluorophores tended to be tightly bound to the filter (inclicated 

by finite levels of non-depolarization of the fluorescence). Reducing the excited 

state lifetimes significantly reduces the total intensity of fluorescence frorn a sample. 

Thus the fluorescence enlrnission from a filter can be reduced by incorporating 

fluorescence quenchers, provided such co~npountls do not cornpromise the cherriical 

perforrrlance of the filter in its intentled role. 

For the performance of these experiments. Pall Corp. acquired a sample holder for 

~nountirlg thin solid sarr~plcs ancl viewing fluorescence from near-r~ormal incidence. 

An angular scale was atldcd to the stantlard tlesigu to permit acljustment of the 

nngle on irlcidence of the exciting light relative to the normal to the plane of the 

sample. This holder is being made available to other usrrs of the bemiline. 

I Photoluminescence Study of Simox Buried Oxide I U ~ I B 

H. Nishikawa (TLIU). J. H. Stathis, (IBhI) and R.E. Stahlbush (NRL) 

Electrically active defects in the buried oxide (BOX) of SIAIOX (Separation by 

Implantation of Oxygen) wafers. or other SiOz films, have been studied mostly with 

electrical (charge sensing) techniques ancl with electron spin resonance (ESR). The 

electrical studies have shown that the buried oxide of SIhIOX has a much higher concentration 

of electron and hole traps than normal thermal oxide antl higher concentration 

of E' centers are observed by ESR measurements in SIhIOX than in thermal 

oxide. These studies concluded that during the high temperature (1300°C) anneal 

that is necessary to form SIhIOX. defects such as oxygen vacancies are formed. In 

this work, defects in the BOX were stntliecl by photol~~rrlinescencc which is a complementary 

technique to electrical and ESR measurements. Electrical measurements 

provide high sensitivity but no structural information and ESR gives structural 

information but can only detect the paramagnetic charge state of a defect. Photcluminescence 

can detect defects in their diamagnetic configuration. Sarrlples used 

in the present cxperirrlent,~ were b~~ried oxide Iwers produced by the SIAIOX technique. 

Samples included low-dose single-implant (Oxygen dose 0.4-0.6~10'" cmp"). 

tlouble-implant (0.0x10'~ cmp2 total tlose) and €1111-close single- antl triple irrlplarit 

(1.7-1.8xlO'~ crnp2 total tlose). The implant energy was 180-200 keV ant1 armealing 

was done in Ar+ 0.5 temperatures in the range 1310-1350°C. One of the full-dose 

triple-implanted samples received a supplemerltal tlosr of O.lxlO'H cln-'. After the 

supplemrntal implant, the annealing temperature was 1000°C. Exarnplc results for 

full-tlosc triple-iu~plantrtl samples with antl without thc s~~pplerrlental oxygen irnplantation 

are discussed below. Ptiotolumir~escer~cc mcasurcmcnts mcrc carried out 

using the UDB bearuline of the Natior~al Synchrotron Light Source equipped with 

an excitation double n~onorhrorr~ator (Sprx 1680). Thr PL from thr sample was 

dispersed by ;c detection nlonochroniator (Chrornex) across t,he 2.5 cm dim1 bialkali 

photocathode of an ITT P414Gi\l position sensitive tlrtector. The tletection syste~rl 

provides time resolution from 1-1511s and simultaneo~~s recording of PL intensity 

in the two polarization directions parallrl antl perpendicular to the excitation polarization. 

Excitation was done in air at a wavelength of 248 nm (hv=5.0 eV). 

The surface Si Iqer was removed for the PL measurer~lent. The spectrnm of the 

BOX (oxide thickness 3550 Xngstrorns) without t,he supplemental irnplant shows 

n PL peak at 280 nrn. On thr other hand, the PL at 280 nm in the BOX with 

supplemental implant was significantly reth~cctl. The decay of the PL follows a 

sirgle exponential with a lifetime of -1 11s. The PL at 280 urn can be ascribed to 

a transition frorn thr excited-singlet to ground (SI-So) states at the site of oxygen 

vacancy . This can be ascribed to a transition from the excited-singlet to ground 

(Sl-SO) states at the site of oxygen vara~icy. Electrical rrleasurements have show^^ 

that SIlIOX with a supplemerltal oxygen tlose has less electron and hole traps. PL 

results from this antl a variety of other BOX samples have been accepted for presention 

at the Serniconductor Interface Specialists Conference to be held Dec 4-6. 

1997. in Charleston. SC.

Use of Fluorescence Homotransfer to Monitor BOPIPY-melittin 

Oligomerization 

S. Scarlata (SUNY at Stony Brook) 

U9B 

Our laboratory has been exploring the possibility of using fluorescence homotrans- 

fer (resonance energy transfer between identical fluorophores) to monitor changes 

in the oligomerization of membrane proteins. Homotransfer is measured by the loss 

in fluorescence anistropy as the energy is transferred between probes. We have used 

a stochastic approach to relate the number of subunits in a protein oligomer to 

the loss in fluorescence anisotropy. We tested this model using fluorescein-labeled 

melittin which is a small peptide whose monomer to tetramer transition can be 

easily controlled. Although we found a good correlation between theory and ex- 

perimental results, a breakdown occurs at higher viscosities or low temperatures 

since these stabilize the formation of non-fluorescent fluorescein dimers. This prob- 

lem is also pronounced when the protein is in a membrane. To minimize the dark 

complex formation, we selected another probe, BODIPY (Molecular Probes, Inc.). 

This probe has a high probability of homotransfer, but is not expected to form dark 

complexes. We selectively labeled melittin with this probe on its C-terminus, and 

found that the homotransfer, as monitored by the loss in fluorescence anisotropy, 

was obeyed. We then measured the anistropy decays, lifetimes and time-dependent 

emission spectra of the BODIPY-melittin monomer and tetramer in 50% glycerol 

at NSLS. We found these time-resolved parameters to be similar, although their 

initial values differ. These results indicate that the rate of exchange of the excited 

energy between the probes in the tetramer is faster than the fluorescent lifetime. 

We are incorporating these results into our model. 

Time Resolved Fluorescence Polarization Measurements for Entire 

Emission Spectra with a Resistive-anode, Single-photon-counting De- 

tector: The Fluorescence Omnilyzer * 

U9B 

J. C. Sutherland, L. A. Kelly, J. G. Trunk, D. C. Monteleone and K. Polewski 

BNL - Biology) 

We report a fluorescence analyzer that records simultaneously the temporal 

profiles for both orthogonal linear polarizations for all wavelengths in a fluores- 

cence emission spectrum. The Analyzer combines a resistive-anode single-photon- 

counting photomultiplier, imaging spectrograph, Wollaston polarizer, multiparam- 

eter analyzer with histogramming memory and standard timing electronics. The 

spectrograph disperses the fluorescence spectrum across the photocathode of the 

photomultiplier, and the Wollaston polarizer separates the spectra of the two polar- 

izations in opposite directions from the center of the photocathode perpendicular to 

the direction of spectral dispersion. The locations at which each photon reaches the 

photocathode is determined by the ratios of the charges read from the four corners 

of the resistive-anode. One of the two address coordinates that determine where in 

histogramming memory each photon is recorded is obtained by measuring the time- 

of-arrival of the photon at the detector relative to the pulse of light that excites the 

fluorescence. The second address coordinate is obtained by combining the most- 

significant bit of the location of the event along the direction on the resistive anode 

corresponding to the polarization of the photon with the multi-bit digital value in- 

dicating photon wavelength. Storing the data directly into histogramming memory 

permits display of the data-set as it is recorded. Both the spectral and temporal 

calibrations of the fluorescence analyzer are independent of the polarization of the 

fluorescence. The 100 ps temporal resolution of the resistive-anode detector is well 

matched to the 1 ns FWHM pulses of light produced by the synchrotron storage 

ring that we use as the excitation source, but laser excitation could also be used 

with this detector. Recording simultaneously all of the data required for the global 

analysis of the time evolution of both linear polarization components of fluorescent, 

and thus time-resolved anisotropy, reduces the duration of exposure of the sample to 

the excitation beam, hence facilitating studies of fragile or photosensitive biological 

specimens. 

* The Fluorescence Omnilyzer was selected by R&D Magazine as one of the 100 most 

important technical products of the year.

U1 

a 

Fluorescence Properties of Recombinant Cardiac Troponin C and its 

- Mutants * 

C. K. Wang (U. of Washington) 

The contraction of vertebrate striated muscle is initiated by the binding of Ca2+ 

to the troponin C (TnC) which is the only ca2+ receptor in the thin filaments. 

TnC obtained from fast skeletal muscle contains four Ca2+ binding sites. Of these 

four sites, sites I and I1 bind Ca2+ specifically, but sites I11 and IV also bind Mg2+ 

competitively. Cardiac TnC (cTnC) contains only three active Ca2+ binding sites 

(called 11, 111, and IV). Site I is inactive due to the defect of the bincling loop. 

Previously utilizing cTnC mutants containing single tryptophan (Trp), we studied 

the effects of Ca2+ and h1g2+ on Trp fluorescence. The results showed that multiple 

lifetimes were seen from most of mutants except cTnC(F74W), in which a single 

lifetime was observed in the presence and absence of divalent cations. We then 

hypothesized that the observetl single lifetime of cTnC(F74W) may result from the 

electron transfer quenching of Trp fluorescence by the amino acid residue Lys 21 on 

helix A. 

To test this hypothesis we have produced two cTnC mutants, cTnC(F74W,K21A) 

and cTnC(F74W,K21&), by replacing the amino acid residue lysine (K) 21 with 

alanine (A) and glutarnine (Q), respectively. Pulsed light from port U9B at the 

National Synchrotron Light Source (NSLS) was used to excite the Trp on cTnC 

mutants. Single photon counting techniques were used to measure time-resolved 

total flnorescence antl anisotropy tlecay. The instrumentation (called fluorescence 

omnilyzer), tlata collection, and tlata analysis procedures have been described in tle- 

tails previously (Kelly, et al., Rev. Sci. Instrum., 1997, 68:2279-2286). Each protein 

was cxcitctl at 295 rlrn antl both parallel and perpendicular polarization components 

were simultaneously recorded for all wavrlengths of a fluorescence spectrum. 

\iTith an excitation at 29.5 nm, at ambient temperature the replacement of K21 

by A results in two lifetimes for the fluorescence tlecay from single Trp at position 

74. This finding indicates that the amino acid resiutle Lys 21 interacts with Trp 

74 on Ca"-binding loop 11. Addition of caw or Mi2+ leads to a small change in 

lifetimes. LVhen K21 is replaced by Q, single lifetime is observed again, however, 

the lifetime becomes significantly shorter than that of cTnC(F74iV). This result 

suggests that an enhanced quenching of Trp 74 fluorescence by Q. Fluorescence 

tlecay of cTnC(F74\IT,K21Q) is sensitive to the binding of Ca2' and/or hIgZi to 

the protein. Interestingly the effect of 11g21 on fluorescence of single tryptophan 

at N-terminal domain is greater than that of Caw. It must be emphasized that 

the two binding sites of cTnC for llgL resides at C-terminal region, however. Trp 

74 resides at Ca2+-binding loop I1 which is in the N-terminal half of the protein. 

These results suggest that indeed Trp 74 on Caw-binding loop I1 interacts with 

Lys 21 on helix -4. and the mechanisnl for the change in fluorescence is likely to be 

electron transfer between the two amino acid residues. 

* This work is supported in part by NIH Grant No. NIH HL52558. 

U9B I Large Value of the Electron-Phonon Coupling Parameter X = 1.15 1 TT7, I 

and the Possibility of Surface Superconductivity at the Be(0001) :iibB 

Surface I I 


The electron-phonon coupling parameter at the Be(0001) surface A, is measured 

using angle resolved photoemission from surface states and found to be 1.15 i 0.1, 

about four times the bulk Be value Xb = 0.24 (see Figure 1). A, is cleterminecl by 

assuming that all of the temperature dependence of the surface state width comes 

from phonon creation/annihilation. In the limit of high temperatures, not quite 

realized for these data, X is proportional to the derivative of the width with respect 

to temperature (see hIcDougall, Balasubramanian, and Jensen, Phys. Rev. B 51, 

13891 (1995)); a more accurate analysis results from a fit to the Debye model. This 

result can be understood sinlply from the large surface to bulk ratio of the Fermi 

level density of states first noted by Chulkov (Surf. Sci. 188. 287 (1987)). A large 

value of X is often associated with a high superconducting transition temperature. 

If the surface is considered as a thin film with high X on a thick sllbstrate with low 

A, the proximity effect wodd destroy any observable interrsting effects. However, 

it was shown by Suhl, hhtthias, ar~d LValker (Phys. Rev. Lctt. 3. 552 (1959)) 

that different hranches of thr Fermi surface - for which surface and bulk states 

qualify - could have different superconducting energy gaps. In the limit of a serni- 

infinite solid the two branches are essentially uncoupled and the surface states can 

superconduct independent of the bulk. Application of the hlcLIillan formula using 

bulk ~honons to estimate the superconducting transition temperature yields 70K 

for the surface transition ternperAture. 

0.6 A 

Straight line fit : A = 1.06 

--- Drbye Yodel fit : A: = 1.25 - 

I 

o . , l , , , , , , , 1 

0 100 200 300 400 500 600 700 800 900 

TEMPERITTRE [K] 

Figure 1. Surface state widths vs.temperature. The error bars on the data are from 

the fits. The open circles are for increasing temperature.

I The VUV Absorption Spectrum of Cold Gas-Phase Methane * 

R. Bersohn (Columbia U.) and J.M. Preses (BNL) 

The absorption spectrum of cold gas-phase methane in the VUV region from 110 

to 140 nm is being measured. The temperature, about 100 K, is approximately the 

surface temperature of Jupiter and Titan, a moon of Saturn. In this research the 

absorption of CH4 will be compared with that of CH3D. The objectives are a) to try 

to understand the structure in the spectrum appearing at the shorter wavelengths, 

b) to compare the absorption with recent ab initio calculations of Mebel and Lin 

and c) to obtain basic data on the most abundant hydrocarbon molecule found 

in the atmospheres of the heavy planets and their satellites at the temperature of 

astronomical observation. At low temperatures, barely perceptible features in the 

absorption spectrum which may be due to vibrational structure could become more 

pronounced. 

* 

Work supported by NASA Grant No. NAG5-4971 (RB). Research performed at 

? BrookhavenNational Laboratory under Contract AE-AC02-76CH00016 with the U.S. DOE 

+ and supported by the Div. of Chemical Sciences, Office of Basic Energy Sciences (JMP). 

Products of the 0(3P) + C3H6 Reaction and Branching Fraction for 

Formation of CH3 * 

R.B. Klemm, S.-C. Kuo, S.K. Ross (BNL) and R.P. Thorn, Jr. (NASAIGSFC) 

u11 

The reactions of ground state atomic oxygen with olefins are of interest in combus- 

tion and atmospheric research because they are fast and because numerous reaction 

channels are thermodynamically allowed. For the 0-atom + propene reaction, there 

are at least ten exothermic product channels: 

Early mass spectrometric studies by Gutman et al. (Chem. Phys. Lett. 1972, 

15, 236) and by Hoyermann et al. (Sixteenth Symposium(Int'1) on Combustion, 

The Combustion Institute, Pittsburgh, 1977, 841) identified channels (2) and (3) 

as major pathways, however, they differed on the importance of other possible 

channels. Hoyermann et al. were able to distinguish CH3C0 from the 13C isotope of 

C3H6 but neither they nor Gutman et al. comment on the CHzCHO isomer. In later 

studies with spectroscopic detection, the CHzCHO radical, was positively identified 

as a major product of the O+C3H6 reaction. Moreover, the yield of CHzCHO 

was reported by Hunziker et al. (J. Photochem., 1981, 17, 377) to decrease with 

increasing pressure of argon, from 0.29 at 40 Torr to 0.19 at 760 Torr. The latest 

study by Knyazev et al. (Int. J. Chem. Kznt. 1992, 24, 545)reported a branching 

fraction of 0.46 for channel (8) by monitoring H-atom resonance fluorescence. 

In the present study, primary products from the O+C3He reaction were generated 

in a discharge flow reactor under kinetically isolated conditions. Mass spectrometric 

detection of reactants and products was accomplished via direct photoionization. 

Qualitative observation of products was accomplished via PIE spectra 

and or adiabatic IE's. The following products were positively identified (species 

(m 1 z)): CH3(15); CzHs(27); C2H4 (28); HCOICzHs (29); HzCO(30); C3H5 (41); 

CH3CO (43); CH3CHO (44); CH3CH=CO (56); and propylene oxide (and possibly 

propanal) (58). 

Additionally, the branching fraction for the formation of CH3 (d[CH3]/d[O]) was 

determined by using calibration experiments coupled with kinetic simulations. The 

value derived, 0.52 f 0.05, is consistent with the results reported by Hunziker et al., 

considering the strong pressure dependence of this branching fraction. 

* The work at BNL was supported by the Chemical Sciences Division, Office of Basic En- 

ergy Sciences, U.S. DOE, under contract No. DE-AC0267CH00016 and by the Laboratory 

Directed Research and Development Program at BNL. RPT, Jr. thanks the NAS/NRC for 

the award of a Research Associateship.

? 

C1 

N 

Far-vacuum UV Circular Dichroism Spectra of Starch Components * I U11 

P. Krzysztof (Agricultural U., Poznan.Poland) 

In order to access to higher energy bands the samples have to be prepared as 

dried gels, films or desolvated samples. Such measurements provide access to transitions 

located on sugar ring ancl linkage atoms which may carry the information 

regarding conformational behavior of the polymer. The vacuum far-UV circular 

dichroism (CD) spectra of the clried samples of amylose and amylopectin measured 

up to 120 nm (10 eV), using synchrotron radiation are reported. The fact that 

the solution CD spectra of amylose ancl amylopectin are different from solid samples 

CD indicates that during clesolvation the lowest ener,qv transition disappears, 

which is a nlixtnre of 2p orbitals of oxygen and carbon. The simplest explanation 

of such behavior is connected with ranclomization of carboxyl groups orientation 

relative to glucose ring upon tlesolvation. At higher energy CD spectra of all solitl 

samples display a broad positive peak in the range 150 -160 nm, which comprise. 

very probably, few electronic transitions present ill the energy range. Positive sign 

of CD for a-D-gll~cans suggests t,hat this conformation is intlepentlent on niolccular 

conformation and linkage. Studies on the electronic transitions involved in that 

band are co11tril)utions from sngar-ring oxygen containing chromphorcs. with the 

excitation originating from the non-bonding n orbital of the oxygen atoms. The 

highest encrgv band, 120 rim, observed in this experiment may be ascribed to s s* 

t,ransitions from 2s orbitals of oxygm arid carbor~ atoms of the glucose ring. The 

fact that tlic position remains similar for santplcs casted from water antl DhISO 

intlicatrs also tl~at those transitions arc locatetl inside the sngar ring ancl are unpertubccl 

by environmental modifications. The changes in CD spectra observed for 

the sarriplcs castetl from DhISO very probably display tlisrnption introcl~~cetl by that 

solvent. Tlic spectra of amylose antl amylopc~ctirt are similar regarding the posit,ions 

anti the shape. which wr rnq take as an ir~(lication that DhISO interacts with both 

polymers that final protlnct has this same conformation what shol~ltl not to he so 

anlazing because both species have this same basic glucositlic ring ns a monomer. 

' This work was supported by grant from Polish Scientific Committee. KBS Grant 5 

P06G 0.54 08. 

A Discharge Flow-Photoionizationh~lass Spectrometric Study of HNO: 

Photoionization Efficiency Spectrum, Ionization Energy and Proton 

Affinity of NO* 

U11 

S.-C. Kuo: Z. Zhang, S.K. Ross. R.B. Klemm (BNL), R. D. Johnson I11 (NET). 

P.S. R. P. Thorn, Jr., and L. J. Stief (NASAIGSFC) 

Photoionization efficiency (PIE) spectra of HNO were measured over the wavelength 

range X = 110 to 125 nm and in the ionization threshold region, X = 118 to 

124 nm, using a discharge flow-photoionization mass spectrometer apparatus. HNO 

was generated in sit11 by the reaction sequence: N + NO t N2 + 0 ; 0 + C2H.l 

-t CH3 + HCO: HCO + NO + HNO + CO. The PIE spectrum clisplays steplike 

behavior near threshold antl an HN-0 stretching frequency in the cation of 1972 

f 67 cm-'. A value of 10.18.1 f 0.012 eV for the adiabatic ionization energy (IE) 

of HNO was obtained from photoionization thresholds, which correspond to the 

HNO'(X~A') t HNO(XIA') transition. This resnlt is the first PIhIS tletermination 

of IE(HN0). Also, an ab initio molecular orbital calcnlation (QCISD(T)/augcc-pVQZ) 

was performed that yields a value for IE(HN0) of 10.186 * 0.050 cV. 

There is good agreement between the experimental antl the theoretical valnes for 

IE(HN0) reported here and that from a recent photoelectron spectroscopy stntly. 

The present experimental va111e for IE(HN0) was employed along with other, known 

thermoclynaniic quantities t,o obtain values for the heat of formation of the FINO 

cation antl the a1)solnte proton affinity of NO: Af~('2!)~(HNO+) = 1089.73 * 1.18 

kJ mol-' (AfH"o(HNO") = 1002.65 * 1.18 kJ mol-I); P.~~w(NO) = 531.55 * 

1.26 k.J rnolp' (PAo(N0) = 526.12 f 1.26 k,J mol-I). 

*\Vork at BNL was snpportctl by the Chemical Sciences Division. Office of Basic 

Energy Scienses, U.S. DOE. nntler Contract No. DE-AC0276CFI0001(i and by 

the Laboratory Directed Research and Drvelopmcnt Program at BNL. PS5I autl 

RPT ttiartk the NAS/NRC for the award of Rcscnrch i\ssociateships. The work at 

NtZSA/CSFC was supported by the NASA Planetary -Atmospheres Research Associatcships. 

The work at NASA/FSFC was s~~pportctl hy Planetary i\trnospheres 

Research Program.

I Fluorescence Measurements of Indole Photoionization Products 

-- 

1 ulll 

P. LeBreton (U. of Illinois at Chicago) 

Preliminary, single-beam, steady-state fluorescence measurements were made of 

aqueous indole solutions at excitation wavelengths between 250 and 200 nm. Indole 

is a model compound for tryptophan, which is a primary radiation damage site in 

proteins. These lie in the energy region of the photoionization conduction-band- 

edge energy threshold. In these experiments, the same wavelength was employed 

to photoionize indole, and to excite the photoionization products. In the future, 

double-beam experiments will be carried out in which the synchrotron beam is used 

for photoionization and a second conventional light source is used for fluorescence 

excitiation. 

In the past, indole photoionization in aqueous solution has been monitored using 

electron scavenging analysis and transient absorption of solvated electrons. Elec- 

tron scavenging analysis only provides information about electron formation. No 

information is provided about the radical cations which are formed simultaneously 

with electron emission. Transient absorption detection is of limited sensitivity. 

The goal of the present measurements is to determine the feasibility of employ- 

ing fluorescence detection as a method for monitoring radical cations formed via 

the aqueous photoionization of indole. Fluorescence detection of photoionization 

products promises greater sensitvity than that offered by transient absorption mea- 

surements. The spectral signature provided by the excitation and emission char- 

acteristics of photoionization products will provide information, which will per- 

mit identification of the radical cationi products and which cannot be obtained 

in electron scavening experiments. In these experiments, the challenge will be to 

discriminate fluroescence associated with small concentratrions of radical cations 

from fluorescence associated with larger concentrations of neutral indole. This will 

be accomplished by examining the influence of radical scavengers on fluroescence 

emission, and by carrying out two-beam, time-resolved fluorescence measurements 

in which detection is synchronized with the ionizing beam. 

Circular Dichroism Evidence for Solution Linkage Flexibility in (1+3)- 

Linked a-D-Mannopyranoside Residues * 

E.S. Stevens (SUNY at Binghamton) 

1 1 

The vacuum UV circular dichroism (CD spectrum of thyl-3-0-(a-Dmannopyranosy1)-a-D-mann~p~ranoside 

in DzO 2 175-200nm) is nearly identical to 

twice the monomer spectrum, both in solution and in films. The lack of a siginificant 

linkage contribution to the dimer spectrum most likely results from motional 

averaging among a variety of solution linkage conformations. The CD evidence for 

significant solution linkage flexibility confirms previous consclusions based on optical 

rotation, and is in agreement with nmr results of others. In the solid state 

the dimer CD (145-200nm) differs from the recently proposed quadrant rule to the 

known dimer crystal structure. 

- 

* This work was supported by NIH Grant GM46465.

? 

C1 I VUV Spectroscopy of Amide Chromophores I U11 I 

J.C. Sutherland, J.G. Trunk (BNL - Biology)? and M.J. Kelley (DuPont Central 

Research, Experimental Station) 

The transformation of polymer surtaces by deep UV light is interesting from both 

the standpoint of science and potential proactical applications. Good data of all 

kinds are sparse for UB wavelengths below about 200 nm and are difficult to obtain 

experimentally. Moreover, polymers are technological materials and can offer more 

complications than necessary, motivating the modelling, as far as possible. Careful 

comparisons among whole polymers and molecular model compounds, and between 

experimental data and computational models are vital to define what "as far as 

possible" really means. 

MATERIALS: hexafluoro isopropanol (HFIP); 616 Nylon from "Dartek film 

in HFIP; PET from "Mylar" 75 LB film; n-hexyl hexanamide, proxy for monomer; 

N, N' dihexyl adipamide, proxy for dirner. 

METHODS: Absorption spectra were recorded with the apparatus normally 

used for the detection of circular dichroism using the pseudeabsorption method. 

which has been clescribed elsewhere.[Sutherland, 1982 186][Sutherland, 1996 5951 

Auxiliary absorption spectra for wavelengths greater than 200 nm were obtained 

with a diode array spectrophotometer. Absorption spectra to 185 nm were obtained 

with a conventional source spectrophotorneter at the Du Pont Central Research 

Laboratory to about 185 nm. hhterials were contained in quartz windowed cells 

with pathlengths of 1.0 and 0.1 mm. 

RESULTS: The spectra fro~n U11 were similar to those from the conventional 

source instruments for the spectral range for which there was spectral overlap, 

indicating that the psel~deabsorbance method was performing adcql~atrly. 

The HFIP only blanks were similar when recortletl before and after the cells were 

filled with polymer sample, indicating that the methods used to clean the cells are 

adequate. 

A peak in absorption is observed at about 190 nm that is ascribed to the 7rz --t 7r3 

transition. 

A shoulder is observed for the nylon compound at about 175 nm that is tentatively 

ascribed to an no --t u,o transition. 

Beginning about 170 nni the red edge of a strong absorption is observed, presllm- 

ably due to the 7r, --t 7rn transition 

DISCUSSION AND CONCLUSIONS: The results are generally in line with 

theoretical expectations. Absorption spectra can be extended to higher photon 

energies by stl~tlying films rather than solutions. LIagnetic circular tlichroisn~ may 

confirm the tentative assignments: such experiments are planned for 1998. 

[l] .J. C. Sutherlantl, P. C. Keck, K. P. Griffin, and P. Z. Takacs, "Simultaneous 

measurement of absorption and circular dichroism in a synchrotron spectrometer", 

Nuclear Instrwnents and Methods 195. 375-379. 1982. 

[2] .J. C. Sutherlancl. "Circular tlichroisrn using synchrotron radiation: frorn ultraviolet 

to x-rays." in Circular Dichroism: Conformational Analysis of Biomolecules. 

edited by Gerald D. Fasman (Plenum Press. Sew York. 1996). pp. 399-633. 

Photoionization Efficiency Spectrum and Ionization Energy of the 

Cyanomethyl Radical CHzCN and Products of the N(4S) + C2H3 

Reaction * 

U11 

R.P. Thorn, Jr., P.S. Monks, L.J. Stief (NASAIGSFC), S.-C. Kuo, Z. Zhang, S.K. 

Ross and R.B. Klemm (BNL) 

Photoionization efficiency (PIE) spectra of the CHzCN radical were measured 

over the wavelength range X = 115 to 130 nm using a discharge flow-photoionization 

mass spectrometer (DF-PIhtlS). The cyanomethyl radical was produced by the reaction 

F + CH3CN + CHzCN + HF and the PIE spectrum displayed steplike 

behavior near threshold. From the half-rise point of the initial step, a value of 

10.280 + 0.010 eV was obtained for the adiabatic ionization energy (IE) of CHzCN. 

This experimental result agrees well with the previous value of 10.1 f 0.2 that 

was determined from the difference in the heats of formation of the cation and the 

neutral by Holmes and hIeyer (J. Phys. Chem. 1995, 99, 1366). It is in even 

better agreement with a value of 10.20 f 0.05 eV that was derived from an nb initio 

calculation by Horn et al. (Ber. Bunsenges. Phys. Chem. 1995, 99, 323). The 

present PIhIS study of the CHzCN radical provides experimental measurements of 

the adiabatic ionization energy that are simultaneously the most direct antl the 

most precise available. For the reaction N("S) + CzH3, the CzHzN radical proctuct 

exhibits a PIE spectrum that may include CHzCN along with another species 

that has a gradl~al threshold that is at a consitlerably longer wavelength than the 

step-like threshold of CHzCN (derived from F + CHnCN). A possible source of 

this difference is the contribution frorn higher energy CzHzN isomers and/or from 

excited CHzCN. In sharp contrast to the results for the N("S) + CzH3 reaction, no 

signal attributable to an isomer of the C2D2N radical wrrq observed from the N("S) 

+ C2D:1 reaction. The CzH3N/C2D3N adtlucts from the N("S) + CzH3/CzD3 reactions 

were also studied. The atltluct was observed to be solely CH3CN for the 

N("S) + C2H:r reaction while for N("S) + CzD3, the PIE spectrum appears to include 

significant contributions from not only the lowest energy isomer, CD3CN, but 

also one or more higher energy isomers. 

*The work at BNL was sl~pport~d by the Chemical Sciences Division, Office of 

Basic Energy Sciences. U.S. DOE. under contract No. DE-AC02786CH00016 ant1 

by the Laboratory Directed Research and Development Program at BNL. PShI and 

RPT,.Jr. thank the NAS/NRC for the award of Research Associateships. The work 

at NASA/GSFC was supported by the Planetary Atmospheres Research Program.

Discharge Flow-Photoionization Mass Spectrometric Study of HOC1: 

Photoionization Efficiency Spectrum and Ionization Energy * 

R. P. Thorn, Jr., L. J. Stief(NASA/Goddard), S.-C. Kuo, and R. B. Klemm(BNL) 

The photoionization efficiency (PIE) spectrum of HOCl was measured over the 

wavelength range X = 102 - 115 nm, using a discharge flow- photoionization mass 

spectrometer apparatus. The PIE spectra displayed steplike behavior near threshold. 

This study represents the first determination of the HOCl photoionization 

efficiency spectrum and the photoionization threshold. A value of 11.120 f 0.006 

eV was obtained for the adiabatic ionization energy (IE) of HOCl from analysis of 

photoion thresholds, corresponding to the HoC~+(X~A") t HOCl (xlA") transition. 

This result compares well with the only previous experimental measurement, 

a photoelectron spectroscopy study that was complicated by the presence of ClzO, 

Clz, and Hz0 features in addition to those due to HOCl. The present result is also 

in good agreement with a recent G2 ab initio calculation by Glukhovtsev et al. 

From the value for IE(HOCl), a value of 999.1 f 3.6 kJ mol-l is calculated 

for Af~(~OC1+) and from the latter, the proton affinity of C10 at T = 0 K is 

determined to be 630.0 f 3.6 kJ mol-l. 

* The work at BNL was supported by the Chemical Sciences Division, Office of Basic Energy 

Sciences, U.S. DOE, under contract No. DE-AC0276CH00016 and by the Laboratory 

Directed Research and Development Program at BNL. RPT, Jr. thanks the NASINRC for 

? the award of a Research Associateship. The work at NASAIGSFC was supported by the 

vr 

vr NASA Upper Atmosphere Research Program. 

I Radiative Recombination in Rare-Earth Doped Insulating Materials * I U11 I 

A. J. Wojtowicz and J. Glodo (Boston U.) 

The aim of the current project was to study carrier capture and recombination 

processes at structured impurities in wide bandgap materials activated by open 

f-shell (RE) ions which potentially may serve as scintillator materials. A simple 

model of a scintillator material describes a scintillation pulse in terms of rise and 

decay times which are determined by radiative (characteristic of the ion, e.g. Ce) 

and host-to-ion transfer rates. Since the unquenched radiative decay rate is limited 

by the value of Einstein coefficient, the Hyman theory requires that to achieve the 

best timing the transfer rate should be infinitely high while decay should be single 

exponential and as fast as possible. This approach highlights the importance of 

both emission and transfer processes which determine the intensity, wavelength and 

pulse shape of the scintillation light. Consequently, we have measured: 1) VUV 

excitation spectra of d-f and f-f luminescences in RE-doped fluorides and Ce- 

doped aluminates to identify various channels of the host-to-ion energy transfer; 

2) luminescence spectra in order to identify those electronic states which are 

targets of specific energy transfer channels identified previously; 3) temporal pulse 

shapes. In the case of direct excitation into the characteristic band (due to the 

f-d transition) the rise times are practically zero, while decays are largely single- 

exponential and radiative-rate-determined. The measurement of rise times under 

excitation favoring some channels of energy transfer identified by VUV spectroscopy 

(above the bandgap and excitonic) clearly show measurable rise-times, as expected. 

Figure 1. Luminescence spectra of Er-doped BaFz under VUV excitation. There 

is a dramatic change upon relatively small variations in the excitation wavelength. 

The highly selective nature of monochromatic optical excitation in VUV points to 

existence of various energy transfer mechanisms like direct excitation, excitonic and 

charge carrier mediated trapping processes. 

* The support and hospitality of Dr. John Sutherland and his group of U11 beamline 

at NSLS is gratefully acknowledged. This work was funded by the Department of Energy, 

Grant No DE-FG-02-90ER61033.

? 

G1 

o 

Evidence for Coherent Emission from the VUV Ring in the Very 

Far Infrared* 

G.L. Carr (NSLS), R.P.S.hI. Lobo (U. Florida & NSLS), J. LaVeigne, D.H. Reitze 

and D.B. Tanner (U. Florida) 

\Tie have observed evidence for coherent synchrotron radiation emission. peaked at 

a wavelength of 7mm (42 GHz), from port U12IR under special operating conditions 

of the VUV ring. This wavelength is much shorter than the electron bunch length 

of about 30cm, and therefore does not appear to be due to the intrinsic shape of the 

electron bunches. The emission appears as quasi-periodic (T -2ms), short bursts 

of radiation. 

The observed wavelength is comparable to the effective cutoff wavelength for the 

bearriline and spectrometer's lightpipe optics (-4n1m) as well as the ring chamber 

(appros. 30rnn1). Therefore. our data does not rule out the presence of coherent 

en~ission at wavelengths beyond about 10mm. The width of the e~nission is not 

quite resolved with the existing instrument, having a spectral resolution of about 

0.12mm at 7mn1 wavelength. 

The coherent enlission appears to be present only when the current per bunch 

exceeds a threshold, which depends on the operating co~lclitions of the ring. For 

example, for operations with E=744LIeV antl the 4th harrnonic cavity at a low 

(ir?jection level) power, the threshold is abont 100ma per bunch. This is observed 

in 1, 3 antl 7-bunch modes. Ramping the electron energy to XOOlIeV shifts the 

current threshold to ahout 1GOrna. Increasing the power to the 4th harmonic cavity 

causes a fi~rther increase in t,he threshold value. 

*Support,etl by DOE Contracts DE-i\C02-7GCF100016 and DE-FG02-96ER45584. 

I bunch 

3 bunch 

7 bunch 

Current ner Bunch [ma] 

Figure 1. Broadband. long wavelength 

infrared signal at U12IR. rneasuretl ver- 

sus bean1 current in the YU\- ring. 

The signal increases linearly with beam 

current until the 100ma thresholtl is 

reached. and then increases approsi- 

mately as the current squared. 

Frequency [cm I 

Figure 2. Spectrum of the coherent emis- 

sion signal. showing a strong peak near 

1.4 cm-' (Tmm wavelength. or about 12 

GHz). 

Design of the U12IR Beamline for Solid State Infrared 

U12IR U12IR 

Spectroscopy* 

G.L. Carr, G.P. Williams and D. Lynch (NSLS) 

The new infrared beamline U12IR is designed to serve the solid state physics community's 

needs for performing IR spectroscopy from wavelengths of a few microns 

out to several millimeters. The beamline uses a 90x90 milliradian mirror extraction 

system similar to beamline U4IR (see Figure 1). bringing the light from the ring's 

UHV environment through a wedged diamond window. However a number of special 

design features have been incorporated in order to reach such long wavelengths 

efficiently, such as a large beamline diameter and a tapered light cone preceding 

the diamond window. \Then the long wavelength (lamellar grating) interferometer 

is used, quasi-optic lightpipe is placed imnlecliately after the cliarr~ontl wir~tlow aritl 

brings the light to this fast interferometer, thus minimizing diffraction losses. Otherwise 

conventional mirror optics are used collimate the infrared aritl transport it to 

the other spectro~neter - a Br~tker IFS 113v. Figure 2 shows the collirnating mirror 

chamber antl spectrometer cntlstatioris with the lightpipe in place. The beaniline's 

spectral range is expected to reach from about 1 crn-I up to 40.000 crriL, although 

the sprctrometer cndstations will reach to only 10.000 cnl-'. A spectral resolution 

of 4.1 cm-' is anticipated. 

* Ihrk supported by DOE Contract DE-AC02-76CH00016.

I Initial Tests of the New Infrared Beamline U12IR I U12IR I 

R.P.S.M. Lobo, J. LaVeigne, D.B. Tanner (U. of Florida), G.L. Carr (NSLS) 

The new infrared beamline U12IR has neared completion, and initial testing of 

the optical instrumentation has begun. Though the beamline delivers light over the 

frequency range from ~1 cm-' to 40,000 cmp', the spectrometer endstations are 

optimized for the long wavelength region. A Bruker IFS 113v will span the range 

from 20 cm-' to beyond 5000 cm-l, while a lamellar grating interferometer will be 

used for the 1 to 100 cm-' range. First measurements have been performed using 

the lamellar grating interferometer and bolometric detectors operating at Tw1.7K 

and 4.2K. Useful signals down to about 2 cm-' have been obtained. A typical 

low resolution interferogram is shown in Figure 1, and the resulting - spectral - signal - 

(obtained by Fourier transform) is shown in Figure 2. 

bv DOE through contracts DE-AC02-76CH00016 and DE-FG02- 

* Su~~orted 

3OOL' . ' I 

Optical Path Difference [mm] 

Figure 1. Interferogram obtained with 

the synchrotron source using the lamel- 

lar grating interferometer. 

Frequency [cm '1 

Figure 2. Typical "single beam" spectral 

signal at a resolution of 2 cm-'. 

A Pulsed Synchronized Laser System for Time-Resolved 1 U121R I 

Spectroscopy* 

D.H. Reitze, J. LaVeigne, D.B. Tanner (U.of Florida), R.P.S.M Lobo (U. Florida 

& NSLS) G.L. Carr (NSLS) 

A custom mode-locked Ti:sapphire laser system has been implemented on the 

VUV floor. The system is a custom Mira unit from Coherent Laser Group, designed 

to produce pulses at a 105.76 MHz pulse repetition frequency (PRF) using the 52.88 

MHz rf signal from the VUV ring. The system is therefore synchronously locked to 

the pulse structure of light emitted by this storage ring. The laser is continuously 

tunable from 0.7 microns to 1 micron wavelengths, and produces up to 10 nJ per 2 

ps duration pulse. A pulse selection system, to match special bunch patterns of the 

ring (i.e., multi-bunch, symmetric 3-bunch, and 1-bunch), has also been developed 

and tested. Modulation of the Ti:sapphire laser phase will allow lock-in detection 

of time-dependent signals. 

The light will be fed to various experiment stations (U12IR in particular) via fiber 

optic cable, allowing time-resolved, pump-probe spectroscopy to be performed. The 

available time resolution is limited by the synchrotron pulse duration, which can be 

as short as ~lOOps under special operating conditions. The longest time between 

pulses is set by the ring orbital period of 170ns. 

* SuDDorted by DOE through Contracts DE-AC02-76CH00016 and DE-FG02- 

Figure 1. Oscilloscope trace showing a Figure 2. Oscillosco~e traces showing 

pulse from the synchronized Ti:sapphire both sine and square wave modulation 

laser. The apparent pulse width is lim- of the Ti:sa~~hire laser pulse phase (re{ited 

by the bandwidth of the photode- ative to the synchrotron). The horizontector 

and electronics. 

tal axis is 2ns per major division.

Large Value of the Electron-Phonon Coupling Parameter X = 1.15 

and the Possibility of Surface Superconductivity at the Be(0001) 

Snrface 

u11, 

UISUB 


The electron-phonon coupling parameter at the Be(0001) surface A, is measured 

using angle resolved photoemission from surface states and found to be 1.15 * 0.1, 

about four times the bulk Be value Xb = 0.24 (see Figure 1). A, is determined by 

assuming that all of the temperature dependence of the surface state width comes 

from phonon creation/annihilation. In the limit of high temperatures, not quite 

realized for these data, X is proportional to the derivative of the width with respect 

to temperature (see McDougall, Balasubramanian, and Jensen, Phys. Rev. B 51, 

13891 (1995)); a more accurate analysis results from a fit to the Debye model. This 

result can be understood simply from the large surface to bulk ratio of the Fermi 

level density of states first noted by Chulkov (Surf. Sci. 188, 287 (1987)). A large 

value of X is often associated with a high superconducting transition temperature. 

If the surface is considered as a thin film with high X on a thick substrate with low 

A, the proximity effect would destroy any observable interesting effects. However, 

it was shown by Suhl, Matthias, and Walker (Phys. Rev. Lett. 3, 552 (1959)) 

that different branches of the Fermi surface - for which surface and bulk states 

qualify - could have different superconducting energy gaps. In the limit of a semi- 

infinite solid the two branches are essentially uncoupled and the surface states can 

superconduct independent of the bulk. Application of the Llcklillan formula using 

bulk phonons to estimate the supercontlucting transition temperature yields 70K 

for the surface transition temperature. 

-Straight line fit : A 

I - - Deby Model I11 : A: = 1.25 . 

0.6 , = 

Figure 1. Surface state widths vs.temperature. The error bars on the data are from 

the fits. The open circles are for increasing temperature. 

Line Shape of the Ag N23m Auger Transition Measured by Auger 

Photoelectron Coincidence Spectroscopy 

A. Danese, Q. Qian, R.A. Bartynski (Rutgers U.), S.L. Hulbert (NSLS) 

U14A 

It is well known that the shallow plevels of the late transition metals have very 

broad and ill-defined spectral line shapes. Owing to strong overlap with the 4d 

bands, the shallow 4p levels of Ag have a very short lifetime hence appear as broad 

( ~ eV 5 wide) features in photoemission spectra. This width is folded into the conventional 

Auger spectrum. By measuring Ag N2,sVV Auger electrons in coincidence 

with Ag 4p photoelectrons of a particular kinetic energy, we have eliminated this 

broadening and revealed the true lineshape of the Auger transition. These coincidence 

spectra are shown in Figures 1 and 2. As has been seen for the M4,sVV 

transition, the lineshape appears to include both quasi-atomic and band-like components 

to its profile. However, in the coinciclence spectra, the band-like component 

is significantly more pronounced. This is most likely because of the elimination of 

inelastic background in the coincidence measurement. A comparison of the relative 

spectral weight contained in each component indicates that the band-like part is 

Ag. In addition to measuring Auger line shapes, extrinsic inelastic background is 

suppressed in APECS because it has a significantly smaller probing depth. As a 

result, one can assess the relative contribution of extrinsic (i.e. caused by inelastic 

scattering on the way to the surface) to intrinsic (i.e. caused by additional excitation 

in the Auger process) contributions to the secondary electron background. In 

our coincidence Auger spectra from Ag, we find that a large fraction of the spectral 

weight appears as inelastic contribution under the primary Auger features. This is 

in sharp contrast to the equivalent spectra from Cu, where almost no background is 

found. It is also interesting to note that in Cu, there is no detectable band-like contribution 

to the Auger spectrum. This suggests that the large intrinsic secondary 

background, which is presumably dominated by 3- and 4-electron Auger-like transitions, 

is coupled to the presence of band-like Auger transitions. 

Figure 1. Figure 2.

Adsorption of NH3 on TiOz(110) Studied by Auger Photoelectron I U14A / 

Coincidence Spectroscopy * 

W.K. Siu, R.A. Bartynski (Rutgers U.), A. Nangia, A.H. Weiss (U. Texas at 

Arlington), X. Wu, and S.L. Hulbert (NSLS) 

We have measured the lineshape of the Ti 3p core level in coincidence with Ti 

M2,3VV Auger electrons from the stoichiometric and vacuum annealed TiO2(110 

surfaces exposed to saturation doses of NH3 at room temperature. Fig. l(a 1 

shows the coincidence photoemission spectrum from the clean stoichiometric surface. 

Emission from ~ i and ~ ~i'+ + ions is associated with residual defects (i.e. 

steps and isolated oxygen vacancies) on the surface. Fig. l(b) shows that upon 

NH3 adsorption, the relative contribution from the ~ i ions ~ is + significantly reduced. 

In contrast, Figs. 2(a) and 2(b) show that in the coincidence spectra from 

the annealed surface, the relative Ti4+ signal increases upon adsorption. 

We interpret the results from the stoichiometric surface to indicate that NH3 

bonds in-plane to the 5-fold coordinated surface Ti ions but does not interact with 

residual defects. For the vacuum annealed surface, NH3 bonds to thermally induced 

oxygen vacancies and inhibits bonding to in-plane Ti ions. This gives rise to the 

increase in ~ i signal ~ + for this surface. The signal from ~i~~ and ~ i'+ that survives 

in Fig. 2(b) is associated with the step edges of the vacuum annealed surface. 

Using estimates of the defect density for these surfaces to normalize the relative 

contributions of different Ti-ions in these spectra, we conclude that when NH3 bonds 

to thermal defects, it prevents adsorption to slightly less than two in-plane Ti ions 

on average. These results are able to explain why a reduction in the saturation 

coverage of NH3 has been seen for the chemically reduced TiOz(110) surface. 

: 8W 

s 

u 600 

e 

g 4w 

'2 2W 

U 

0 

M 66 68 70 72 64 66 68 70 n 

Kinetic Energy (eV) Kinetic Energy (eV) 

Figure 1. 

* Funded under grant number NSF-DMR 

94-11610. 

2500 

g4w 

Y 

8" 

$ ZW 

9 100 

0 

M 66 68 70 72 64 66 @ 70 72 

Kinetic Energy (eV) Kinetic Energy (eV) 

Figure 2.

Beamline X1A 

ABSTRACTS 

X-Ray Beamlines 

Soft X-ray Imaging and C-XANES Linear Dichroism of Nematic Phase Transitions in 

Coal Derived Liquids .......................................................................... 

G.D. Cody (Carnegie Institute of Washington) 

Carbon and Oxygen XANES and X-ray Imaging of Chemically Differentiated Regions 

in the Cell Wall Structure of Ancient (40-150 Ma) Wood ....................................... 


C-XANES Linear Dichroism Studies of Single Crystals of Polycyclic Aromatic Hydrocarbons ... 

G. D. Cody (Carnegie Institution of Washington), H. Ade (North Carolina State U.), 

S. Wirick (SUNY at Stony Brook), and J. Waldbaur (Dartmouth U.) 

X-Ray Radiation Damage of PMMA, PC, and Nylon 6 ......................................... 

T. Coffey and H. Ade (NCSU) 

A High Rate Gas Proportional Counter For Soft X-Ray Microscopy ............................. 

M. Feser (SUNY at Stony Brook), G. Smith, B. Yu (BNL), J. Kirz, and 

C. Jacobsen (SUNY at Stony Brook) 

The Spatial Distribution and Bonding States of Carbon in the ALH84001 Meteorite 

from Mars ..................................................................................... 

G.J. Flynn (SUNY at Plattsburgh), L.P. Keller (MVA, Inc.), C. Jacobsen and 

S. Wirick (SUNY at Stony Brook) 

Identification of Organic Compounds in the ALH84001 Meteorite from Mars .................... 

G. J. Flynn (SUNY at Plattsburgh), L. P. Keller and M. A. Miller (MVA Inc.) 

Carbon Mapping and Carbon-XANES Measurements on Interplanetary Dust Particles .......... 

G. J. Flynn (SUNY at Plattsburgh), L. P. Keller (MVA Inc.), S. Wirick and 

C. Jacobsen (SUNY at Stony Brook) 

Determination of Partial Miscibility in Phase Separated PBT-PC Blends by STXM ............. 

Y. Gao, T. Banach, V. Watkins, G. Hutchins (GE), D. Pierson, A.P. Smith, H. Ade (NCSU) 

X-ray Microscopy of Frozen Hydrated Specimen ................................................ 

J. Maser, S. Ang, A. Osanna, S. Spector, C. Jacobsen, J. Kirz (SUNY at Stony Brook) 

Lanthanide Polychelate Probes for Scanning X-Ray Microscopy ................................ 

M.M. Moronne (LBNL) 

Soft X-Ray Spectromicroscopy Studies on Aqueous Clay- and Soil Suspensions ................. 

U. Neuhausler (SUNY at Stony Brook, U. Gottingen), C. Jacobsen (SUNY 

at Stony Brook), D. Schulze (Purdue U.), D. Stott (USDA), and S. Abend (U. Kiel) 

Soft X-ray Spectroscopy of Amino Acids and Peptides .......................................... 

A. Osanna, C. Jacobsen, and J. Kirz (SUNY at Stony Brook) 

Soft X-ray Spectroscopy of Frozen Hydrated Specimens ......................................... 

A. Osanna, C. Jacobsen, J. Kirz, J. Maser and S. Wang (SUNY at Stony Brook), 

R.Balhorn (LLNL) 

Morphology of Rubber Toughened PMMA Blends with X-ray Microscopy ....................... 

A. P. Smith, H. Ade, R. J. Spontak and C. C. Koch (NCSU)

Morphological Cliaractcrization of hIcclia~iically Alloyrd PET/Vcctra Bl(wis with X-ray 

Microscopy .................................................................................... B-34 

A. P. Smith, C. Bai. H. Adc. R. J. Spontak. C. hl. Billik. C. C. I

Beamline X3A1 

Structure of the Cyclodextrin/p-nitroaminobiphenyl hostlguest Complex ...................... 

T. Brett (U. of Nebraska), A. Darovsky and P. Coppens (SUNY at Buffalo) 

Single Crystal Analysis of a New High Pressure Fe-bearing Silicate .............................. 

T. Gasparik, C.L. Cahill, J.B. Parise, (CHiPR, SUNY at Stony Brook) 

The Electron Density Distribution of MoO3(dipic)(HMPA) at 28 K ............................. 

B.B. Iversen, F. K. Larsen, G. H. K. Madsen, C. Wilson, E. Moeller (U. of Aarhus), 

D. Young, and A. J. Schultz (ANL) 

Single Crystal X-Ray Analysis of a Novel Perovskite CaMnTi206 ............................... 

J.-H. Park, C. L. Cahill, and J.B. Parise (CHiPR, SUNY at Stony Brook) 

The Importance of Correcting Reflection Intensities Recorded on Imaging Plates for 

Incomplete Absorption in the Phosphor Layer .................................................. 

J. Zaleski, G. Wu, L. Ribaud and P. Coppens (SUNY at Buffalo) 

Beamline X3A2 

Synchrotron Small-angle X-ray Scattering Studies on Crystallization and Structure of 

Associated Polymer Blends .................................................................... 

K. Inomata, L.-Z. Liu, B. Chu (SUNY at Stony Brook), and T. Nose 

(Tokyo Institute of Technology) 

Crystalline Structure and Morphology of Microphases in Compatible Mixtures of 

Tetrahydrofuran-Methyl Methacrylate Diblock Copolymer and Polytetrahydrofuran ............. 

L.-Z. Liu and B. Chu (SUNY at Stony Brook) 

Phase Diagrams and Gelation Structures of B5Eg1B5 and B6E46B6 Triblock Copolymers 

in Aqueous Solution ........................................................................... 

T. Liu, C. Wu, D. Liang and B. Chu (SUNY at Stony Brook) 

Low-temperature Resonance Scattering of a Mixed-valence Iron Complex with a 

Distorted-triangular FesO Core ................................................................ 

G. Wu, Y. Zhang, L. Ribaud and P. Coppens (SUNY at Buffalo) 

Supramolecular Structures of Complexes Formed by Poly(methacrylate-co-N-isopropylacrylamide) 

Gels with Hexadecvltrimethvlammonium Bromide .............................................. 

S. Zhou, F. ~eh, B. chi (SUNY at Stony Brook) and C. Burger (Max Plank Institut Germany) 

Beamline X3B1 

The Crystal Structure of Rb6Pb5cll6 and its Determination by X-ray Powder Diffraction 

using Anomalous Dispersion .................................................................. 

H. P. Beck, M. Schramm, R. Haberkorn (U. of Saarland), R. E. Dinnebier (U. of 

Bayreuth) and P. W. Stephens (SUNY at Stony Brook) 

Anisotropic Strain of K4C6O at Low Temperatures .............................................. 

G.M. Bendele and P.W. Stephens (SUNY at Stony Brook) 

Na2KC60: Determining the Orientation of Fullerenes in the Lattice ............................. 

G.M. Bendele, P.W. Stephens (SUNY at Stony Brook), and L. Forro (EPF, Lausanne) 

Effect of Charge State on Bonding Geometry: Na2RbCso ....................................... 

G.M. Bendele, P.W. Stephens (SUNY at Stony Brook), K. Prassides, K. Vavekis, 

K. Kordatos (U. of Sussex, UK), and K. Tanigaki (NEC Tsukuba, Japan) 

Powder Diffraction Structure of Fluorenylsodium ............................................... 

R. E. Dinnebier (U. of Bayreuth) and F. Olbrich (U. of Magdeburg) 

Study the Phase Diagrams of L64/water/CdC12 Complex Systems by SAXS .................... 

T. Liu, C. Wu, D. Liang and B. Chu (SUNY at Stony Brook) 

Formation of Clay Minerals Replacing Diatom Cells in Amazon Delta Sedimets ................. 

P. Michalopoulos, R. C. Aller, P.W. Stephens (SUNY at Stony Brook) 

Na4Cso: An Alkali Intercalated Two-Dimensional Polymer ..................................... 

G. Oszlanyi, G. Faigel (Res. Institute for Solid State Physics) and G. Baumgartner, 

L. Forro (Ecole Polytechnique Federale de Lausanne)

Mcasurcincnt of Cohcrcnt Scatter Form Factors in Tisslics in Support of RIolitc Cwrlo 

Si~lllilatioii of Maininograpliy .................................................................. 

D. E. Peplow and K. Vergllcse (NC Statc University) 

B-51 

Rotational Order in CO Intercalated CGO Crystals ............................................. B-52 

S. vanSinaalcn, R. E. Dinnclicr (U. of Bayreutli. Gcnnany). I. Hollcmaii. 

G. von Heldcn. G. AiIcijcr (U. of Nijmcgcn. The Ndlicrlands) 

Beamline X3B2 

In S7tu Diffuse Scattering Studies of Ag(ll1) Daring Low Tcmpcratlirc Hoinocpitasy ........ B-52 

W.C. Elliott, P.F. hliccli (U. of Rlissouri-Columbia). and P.\V. Stcphc~s 

(SUNY at Stony Brook) 

Beamline X4A 

Structure Of a Crc Recoinhinase-DNA Site-specific Rccom1)ination Synapse ................... B-5.1 

F. Gno, D. N. Gopanl. and G. D. Van Duync (U. of Pcnn.) 

Beamline X6B 

In situ Surface X-ra~r Diffraction Study on RuOz(lOO) Siiiglc Crystal ......................... B-53 

Y. C1111, J. Ta~~zcr, H. You, and Z. Nagy (ANL) 

Levitation Apparat>us for Structural Studies of High Tcmpcrat~irc Liquids IJsing Synclrrotron 

Radiation ...................................................................................... B-54 

S. Krishnan, J. J. Felt,en! J. E. Rix: J. K. R. Wcl~cr. P. C. Nordinc 

(Containcrlcss Rcscarch, Inc.), h4. A. Beno, S. Ansrl. arid D. L. Price (ANL) 

X-Ray Ii~vcstigation of the Transformation of Crystal Structures Ind~iccd hy hIo 

Sccding Layers ................................................................................. B-54 

C.H. Lee (Tsing-Hua U. ,Taiwan). J. C. A. Htiang and Y .RI. HII (Chciig-Kiliig 

U., Taiwan), and M. Shih (Clliing-Hsin U.. Taiwan) 

In Sztu Study of the Growth of OTS Self-Assembled RIonolaycrs on Silicon ...................... B-55 

A.G. Richter, M.K. Durlin, C-J. Yu, and P. Dutta (Nortliwcstcrn U.) 

Beamline X7A 

Strong Nega.tive Tliermal Expansion in Siliceous Faiijasitc .................................... B-55 

M. P. Attficld and A. W. Sleight (Oregon Statc U.) 

Structural Changes, Clustering and Photo-irrdi~ccd Pllasc Scgrcgi~tion in Pro,7C:ao,:cRhO:( ....... B-5G 

D. E. Cox (BNL), P. G. Radaclli (ILL. Grcnol)l~), hl. hkrczio (AIASPEC-CNR. 

Parina), and S.-W. Clicong (Lnccnt,) 

High Prcssnre and Low Tempcrat~irc Sti~dy of the LTO to LTT Pliasc Transition ill 

La(l,475)Ndio.4)Sri0,126)C~i0 .................................................................... B-56 

M. Crawford, R. Harlow, E. AlcCarron (DuPoiit), S. Tozcr (Florida State U.). 

and D. Cox (BNL) 

Encrgy-dispcrsivc Surface X-ray Scattering Stlidy of Thin Ccria Ovcrlaycr on Zirconia .......... 0-57 

W. Dinowski (U. of Pennsylva~ria) 

X-R.ay Diffraction of CRlR Sample La1.4Sr~ .GhIi120i ............................................ B-57 

W. Dinowski and T. Egaini (U. of Pcnnsylvania) 

The Crystal Structllrc of BidA11~01.1: Tlrc Use of a Siemens CCD Drtcctor wit11 Sliort- 

Wavclcngth Radiat,ion .......................................................................... B-58 

R. Harlow (D~~Poilt,), J. Parisc (SUNY at Stony Brook), J. Pliillips i~nd C. CAI~I~R~I:~ 

(Sicmcns), and J. Hanson (BNL) 

High Prcss~irc Powder Diffraction Studies of Zeolite Na-A ...................................... 13-58 

J. A. Hriljac, I. Ganlcson and P. P. Edwards (U. Birminglram. UK) 

Lattice Parainctcrs and Phase Transitions in La1-,Sr, RII~O,~ (x-0.12.0.17) ..................... B-50 

T. Iglcsias, D. E Cox. and G. Shiranc (BNL), K. Hirota (Toliokii U.)

In-sztu Ion Exchange Using the Small Environmental Cell for Real Time Study:(SECRETS) ..... 

Y. Lee and J.B. Parise (SUNY at Stony Brook) 

Location of CF3C1 in Partially-hydrated Maximum Aluminum Na,K-X type Zeolites ............ 

Y. Lee, J.B. Parise, and P. Norby (SUNY at Stony Brook) 

Low Temperature X-ray Diffraction Study of La2-,-,Sr,Nd, Cu04 ............................. 

A. R. Moodenbaugh, L. H. Lewis, D. E. Cox, and S. Soman (BNL) 

High Pressure-Hgh Temperature Synthesis of a Novel Perovskite CaMnTia06 ................... 

J.-H. Park and J.B. Parise (CHiPR, SUNY at Stony Brook) 

Ab Initio Crystal Structure Solutions of Metal Phosphonatcs from Synchrotron 

Powder X-Ray Data ........................................................................... 

D.M. Poojary, D. Grohol, F. Gingl, and A. Clearfield (Texas A&M University) 

Certification of Zeolite Standard Reference Materials ........................................... 

B.H. Toby and N. Khosrovani (NIST) 

Siting of the Structure Directing Agent in Zeolite CIT-1 ........................................ 

B.H. Toby, N. Khosrovani (NIST) and M. Davis (Caltech) 

Direct Evidence of Charge Disproportionation in CaFe03 ....................................... 

P.M. Woodward (BNL) 

Low Temperature Phase Transitions in Nd0.5Sr0.5Mn03 ........................................ 

P.M. Woodward, T. Vogt, D.E. Cox (BNL), C.N.R. Rao (Indian Institute of Science) 

and A.K. Cheetham (UCSB) 

The Influence of Cation Size on the Structural Features of Lno,5Ao,5Mn03 Perovskites 

at Room Temperature ......................................................................... 

P.M. Woodward, T. Vogt, D.E. Cox (BNL), C.N.R. Rao (Indian Institute of Science) and 

A.K. Cheetham (UCSB) 

Structural Analyses of Stuffed Quartz Phases Along the LiAlSi04-Si02 Join .................... 

H. Xu, P.J. Heaney, D.M. Yates (Princeton U.), J. Liu (SUNY at Stony Brook), A. Navrotsky 

(Princeton U.) and R.C. Liebermann (SUNY at Stony Brook) 

Beamline X7B 

Time Resolved In-Sztu Diffraction Studies of Intercalation Processes: Intercalation of 1,6- 

Hexanediamine in a-Zr(HP04)2.H20 .......................................................... 

A. M. Krogh Andersen, E. Krogh Andersen, I. G. Krogh Andersen 

(Odense U., Denmark), P. Norby (SUNY at Stony Brook) and J. C. Hanson (BNL) 

Time Resolved In-Sztu Powder Diffraction Study of the Process: LaMn03.00 + 

Lao.ggMnl.o103.14 + LaMn03.0~ .............................................................. 

A. M. Krogh Andersen, E. Krogh Andersen, I. G. Krogh Andersen 

(U. of Odense, Denmark), P. Norby (SUNY at Stony Brook) and J. C. Hanson (BNL) 

Temperature Resolved Diffraction: Lattice Constants and Phase Changes in Lanthanum 

Manganate .................................................................................... 

E. Krogh Andersen, I. G. Krogh Andersen (U. Odense, Denmark), P. Norby 

(SUNY at Stony Brook) and J. C. Hanson (BNL) 

A Time-resolved X-ray Powder Diffraction Study of Phase Transformations in the 

Quinuclidine-Mn-Ge-S System .................................................................. 

C.L Cahill, Y. KO, J.B. Parise (SUNY at Stony Brook) 

In sztu X-ray Powder Diffraction Study of the Synthesis of DEA-Ins-SB1 and DEA-Ins-SB2 .... 

C.L. Cahill, Y. KO and J.B. Parise (SUNY at Stony Brook) 

A Small Environmental Cell for Real Time Studies (SECReTS) ................................. 

C.L. Cahill, P. Norby, C. Koleda, J.B. Parise (SUNY at Stony Brook) 

Reaction Kinetics of the Crystallization of MnAPO-5(AFI) and ZnAPO-47 (CHA) .............. 

A. Noerlund Christensen (Aarhus U.), T. R. Jensen (U. of Odense), P. Norby 

(SUNY at Stony Brook), J. Hanson (BNL)

HFC and HCFC Reactivity and St~ucturc Cllaractcrimtion on Cation EXC~I;III~(Y~ F;ulji\\itt>~ .... B-68 

M.F. Ciraolo, P. Norby, C.P. Grq- (SUNY at Stony Blook), J.C. 

Hans011 (BNL), and D.R. Corlin (Dlipont) 

Cation Migration in Zeolites: An In S7fu Powder Diffraction and MAS NAIR Sti~tly of the 

Structure of Zeolite Cs(Na)Y During Dchydiation .............................................. B-69 

C. P. Grcy, P. Norl~y, F. I. Poslini (SUNY at Stony B~ook). A. F. G~~alti(~i (RIodcna IT), 

J. H;inson (BNL) 

In szfu XRPD Study of the Crystallization of Zeolite? fioin Natilral Halloysitc .................. B-G!) 

A.F. Gualticri (U. of hlodcna, Italy), P. Norby (SUNY at Stony Blook). and J C. Milnson (BNL) 

Preliminary X-ray Reflectivity Stlidy of Intcrdiffiision in Q~~antiinl \.lTcll Strl~cturcs .............. 

S. A. Holt, A.S. Brown (Au~tr:llii~n National U.) and D.C. Crcagh (TJ. of Ca111)crra) 

Thc Low Tcnlpcratiirc Structures of Tls(AISiOl)c and Agc,(AISiOl)s from Imilgc' Pli~tc 

Powder Diffraction Data ....................................................................... 

B. B. Ivcrscn, S. Lattnrncr, C. Brown, N. Blakc. G.D. Stucky (U. of Ci~lifor~~iil 

at Santa Barl~ara) and P. Norhy and J. Hanson (BNL) 

The Struct,nrc and Dynamics of Sodilnn Sodalitc as a Function of Tcmpcrat~~rc ................. 

B. B. Ivcrscn, S. Lattl~rncr, C. Brown, N. Blakc, G. D. Stlicky (U. of California 

at Santa. Barbara), P. Norhy, and J. Hanson (BNL) 

Str~ictiiral Origin of tlic Reinarkaldc AIcchanical Properties of Prl~ni~s Scrriili\ Bark ............. 

B. B. Ivcrscn, C. Zarcmlxl, X. Xu, F. W~~tll. G. D. Stwky. (U. of California) 

In-situ Stlidics of Etjhylcnc Sorption in CUA~C~.~ ................................................ 

H. Liu, M.F. Ciraolo, C.P. Grcy (SUNY at Stony Brook). J. Hi~nson (BNL), 

J. Martin and R.. Sullivan (NC State) 

In, ssitu Diffra,ction St~idics of t,llc Akagancitc-hematite Reaction ................................. 

K. Niclscn, K. Stahl (DTU), J.C. Hanson. P. Norl~y (BNL) J.Z. Jiang (DTU) and 

J. van Lanschot (Sclmol of Conscrvation) 

Time-R,csolvcd, In,-Situ X-Ray Diffract,ion Studies of the Hydrothermal Syntlltws of 

Microporous Gallium Fl~iorophosphatcs ........................................................ 

D. O'Harc, J.S.O. Evans, R. J. Francis, P.S. Halasyamani (Oxford U.) , P.1. Norl)y, 

J. Hanson (BNL) 

Phasc Transformations in CoAlo04 and NiAlo04 Catalysts: Time-Rcsolvcd Synchrotron 

XRD Studies .................................................................................. 

J.A. Rodrigilcz, S. Cl~at,iirvedi, J.C. Hanson (BNL), J.L. Brito and A. A1l)ornox (IVIC) 

Structures From Sinall Single Crystals of ~ ~~-I~(~II):~[AI:~P~O~~]XH~O 

and Ir(ch~n):~[A1~P:~01~] ... 

A. P. Wilkinson (Ga Tech), D. J. MTillii~ms (Kcnncsaw St.). and J. C. Hanson (BNL) 

Beamline X8A 

AXAF Synchrotron Calil~rations over 2010-6200 cV .......................................... 

D.E. Gracsslc. A.,J. Biirck. A.N. Clark. J..J. Fitch. J.B. Sivccncy (Sn~itl~sonii~n 

Astrophysical Observatory), and R.L. Blakc (RkD Scrviccs. Prop.) 

AXAF Synchrotron Reflectance Calihtions 2010-2400 cV - Completion Rtyort ............... 

D.E. Gracsslc, A.J. Burck. A.M. Clark. .J.J. Fitch. J.B. Sn-ccncy (Smitl~sonian 

Astrophysical Ol)scrvatory)and R.L. Blakc (RkD Services. Prop.) 

AXAF Synchrotron Reflectance Calilxations over 2010-6200 cV Ycar 1 ....................... 

D.E. Gracsslc, A.J. Burck, A.M. Clark. J.J. Fitch. J.B. Swccncy (Sn~itl~soniiln 

Astrophysical Observatory), and R.L. Blakc (RkD Scrviccs. Prop.) 

AXAF Synchrotron Reflectance Calihtions 2250-2000 eV - Complction Rcport ............... 

D.E. Gracsslc, A.,J. Burck. J..J. Fitch. 5.13. Sviccncy (Smitllsonian Astrophysicid 

Obscrvatory), and R.L. Blakc (RkD Scrviccs. Prop.)

Beamline X8C 

Scattering Studies of AXAF Witness Mirrors ................................................ 

R.L. Blake (R&D Services, Prop.), A. J. Burek, and D.E. Graessle (Smithsonian 

Astrophysical Observatory) 

AXAF Synchrotron Reflectance Calibrations 5-12 keV - Progress Report ....................... 

D.E. Graessle, A.J. Burek, A.M. Clark, J.J. Fitch, J.B. Sweeney (Smithsonian 

Astrophysical Observatory), R.L. Blake (R&D Services, Prop.) 

AXAF Synchrotron Reflectance Calibrations 5-12 keV ......................................... 

D.E. Graessle, A. J. Burek, J. J. Fitch, J.B. Sweeney (Smithsonian 

Astrophysical Observatory), and R.L. Blake (R&D Services, Prop.) 

Structural Studies of Gene 5 Protein-ss DNA Complexes ........................................ 

T. C. Terwlliger, R. G. Nanni (LANL) 

Beamline X9A 

TATA Binding Protein: Interactions with DNA ............................................... 

M. Brenowitz, M. Sullivan, B. Sclavi, S. Maleknia, S. Moller, B. Gilden (AECOM) 

Single Band Densitometric Analysis Synchrotron X-Ray Footprinting Autoradiograms ........... 

M. Brenowitz, T. Wexler and E. Jamison (AECOM) 

A Resource Dedicated to Time-Resolved X-Ray Footprinting ................................... 

M. Chance, M. Brenowitz and M. Sullivan (AECOM) 

The Folding of an Immobile DNA Branched Junction ........................................... 

M. Chance, B. Sclavi. M. Brenowitz (AECOM), N.C. Seeman, and H. Yan (NYU) 

Time-Resolved Synchrotron X-Ray Footprinting ................................................ 

M.R. Chance, M. Sullivan, B. Sclavi, M. Brenowitz (AECOM), and S. Woodson (U. 

of Maryland) 

Fast Folding of the Tetrahymena Ribozyme: Mutants and P4-P6 Domain Folding ............... 

M.R. Chance, M. Sullivan, B. Sclavi, M. Brenowitz (AECOM), S. Woodson, M. Deras 

(U. of Maryland), J. Williamson, and M. Rook (MIT) 

Time-Resolved X-Ray Footprinting of Cytochrome c ............................................ 

I. Kravtsov, S.D. Maleknia and M. Chance (AECOM) 

Synchrotron X-Ray Induced Modifications of Peptides .......................................... 

S.D. Maleknia and M. Chance (AECOM) 

Beamline X9B 

The Structure of an Actin-crosslinking domain from Human Fimbrin ......................... 

S. Almo, S. Goldsmith, M. Sullivan, and A. Fedorov (AECOM) 

Synchrotron Crystallography Structural Analysis of Profillin .................................... 

S. Almo, N. Mahoney, and M. Sullivan (AECOM) 

Active Site Targeting of Protein Tyrosine Phosphatases by Synchrotron Crystallography ........ 

S. Almo, Y. Puius, M. Sullivan, Z-Y. Zhang, and D. Lawrence (AECOM) 

Frozen Solutions and Vectorially-Oriented Single Monolayers of Oriented Membrane Herme 

Proteins ....................................................................................... 

J.K. Blasie, A. Edwards (U. of Pennsylvania) and K. Zhang (IIT) 

AUTOFIT 1.0, A New Software for XAS Global Mapping ...................................... 

M. Chance, E. Scheuring, Wu-Xin Huang (AECOM) 

Structural Studies of Optically Rubbed Polymers ............................................... 

P.A. Heiney, S.S. Ghosh, O.Y. Mindyuk and M. Stetzer (U. of Pennsylvania) 

Coordination of Co (11) Protoporphyrin-Substituted Hemoproteins .............................. 

C. Lee, E. Scheuring, M. Chance and J. Peisach (AECOM) 

Biological Metal Clusters ....................................................................... 

M. Maroney, S. Choudhury, C. Allan, Z. Gu, G. Davidson, and K. Bose (U. of Mass.)

EXAFS Cliaractcrization of the Zinc Binding Sitc i11 Col~alami~~-D~~pclitlc~it RIt~tliioni~ic~ Splltl~i~sc~ 

K. Pcariso, C.W. Goulding. R.G. blattllcws. and .J.E. Pcnncr-H;11111 (U. of bIicliig;~~i) 

Temporal Speciation of Zinc in Zchrafish (Dc~nio Rlro) E1n1)ryos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

K. Pcariso, F. Su, J. Kuwada, J.E. Pcnncr-Haliii (U. of Rlichigm) 

X-Ray Absorption Spectroscopy of Nucleopliilic Z11 Eiizyiiics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

J. Pcnncr-Hdin and K. Pcariso (U. of blicliigan) 

Temporal Climgcs in Z11 Speciation During Cell Dcvclopmcnt . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

J. Penncr-Hdin and K. Pcariso (U. of blicliigan) 

A Low Angle Diffract,ion Study of tlic Struct,iirc of tlic Actomyosin Coiiiples: Eff~cts of 

ADP Biiidiiig . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

K. Poolc, M. Lorenz, P. Ellison, G. Evans. G. Roscnhaiun. P. Bocscckc. K.C. Hol~iics. 

C.R. Crcino (Max Planck Inst.) 

Esch,erichia Coli Priinas~ Zinc Struct,urc is Sensitive to tllc Binding of ATP and 

High Magncsiuin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

L.S. Powers and MA. Griep (Utah Statc U.) 

EXAFS Studit:~ of Nonl~cmc Iron Enzymes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

L.Quc, Jr., L.Sli11, X.\;ITaiig, K.Chcn, H.Hsn (U. of bli~incsota) 

Metal Cluster Active Sites in Protein . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

L. Quc, Jr., L. Sl111. X. Wang, K. Chcn and S. hlandal (U. of RIinncsotw) 

Thcr~nophillic Alcohol Dchydrogenascs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

I. Sagi (Weiz~naim Instit,~lt,c of Science) 

EXAFS of the Low Spin Ferric Center of Nitrilc Hydrata~c . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

R.C. Scarrow, B. Stricklcr, D. Pringlc (Hwvcrford College) and bI. Nclson (D11Pont) 

Global Mapping of XAS Data: Stnicturc of the Activc Sitc of Co1,wlamin Eiizymrs . . . . . . . . . 

E. Sclicuring, M. Cllancc (AECORI), R. Bancrjcc. and R. Padmak~~~iiar (TJ. of N(4)r;lskil) 

Beamline XlOB 

Structure and Tlicrmally Indilced Failure of Organic LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

P. Fcnter, F. Schrcihcr, V. Bulovif and S. R. Forrest (Priilcctoii 1Jniv.) 

Surface X-ray Diffraction Studies of RIonol:~ycrs of w-alkcnrthiol oil Ail(111) . . . . . . . . . . . . . . . . 

T.Y.B. Lcnng, P. Fcntcr, F. Sclirci1,cr. P. Eiscri1)rrgcr and G. Scolcs (Priiiccton U.) 

In,-situ Studies of the Growth of Coasscmblcd Slirfactant/Silica Fillils . . . . . . . . . . . . . . . . . . . . . . . 

L. Zliou, P. Fcntcr, I. Aksay, P. Eiscnl~~ger (Pri~icctoii U.) 

Beamline Xl 1 A 

Local Structure of DilutcTen~ary 3d Transition hlctal Dopants in Ni%Al . . . . . . . . . . . . . . . . . . 

M. Bnlasnbramania11, R. Lyvcr. J. I. Bltdnick and D. b1. Pcnsc (U. of Connc.ctic11t) 

Prcfcrciltial Co Si bonding at the Co/SiGc(100) interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

B. BOYRIIOV, P. Gocllcr, D. Sayers. and R. Ncinanich (NCSU) 

Co-deposition of Colmlt Disilicidc on Silicon-Gcr~ilani~~n Tliiil Films . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

P Gocllcr (No. Carolina State U.) 

Stability of Heavy-Metal Snlfidcs Diiriiig Oxidation of Conta~ninatcd Soil from a 

Superfund Sitc . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 

P. D. Hanscn, D. Hcstcr1)crg. 14'. Zlioi~. and D. E. Sayers (NC Statc) 

XAFS Study of Copper Binding with a Slilfiir-Rich Hilmic Acid . . . . . . . . . . . . . . . . . . . . . . . . . . 

D. Hcstcrhcrg, D. E. Sayers, \;IT. Zlloli. and I

An XAS Study of Corrosion Characteristics in ABsType Metal Hydride Electrodes ............. 

S. Mukerjee, J. McBreen, J. J. Reilly, J.R. Johnson and G.D. Adzic (BNL) 

Local Structure of Br in Brominated-YBCO .................................................... 

D. Potrepka, M. Balasubramanian, J. Budnick and D. Fenner (U. of Connecticut) 

Local Coordination of Ba and Pb in Calcite from XAFS Spectroscopy .......................... 

R.J. Reeder (SUNY at Stony Brook) and G.M. Lamble (LBNL) 

Kinetics and Mechanisms of Trace Metal Sorption at the Minerallwater Interface: 

A Time-Resolved Study ........................................................................ 

A. M. Scheidegger, D. R. Roberts, D. G. Strawn and D. L. Sparks (U. of Delaware) 

Interface Stability of TitaniumISilicon on 6H Sic-(0001) ....................................... 

A. J. Stoltz, B. I. Boyanov, D. E. Sayers, and R. J. Nemanich (NCSU) 

EXAFS Studies of Sol-gel Processed KTN and PZT .......................................... 

A. P. Wilkinson, J. Xu and S. Pattanaik (Georgia Tech) 

Beamline X12A 

A Tunable LaueIBent-Laue Monochromator with Fixed Second Crystal for Synchrotron 

Radiation ................................................................................. 

Z. Zhong, G. Le Duc (NSLS), D. Chapman (CSRRI, IIT), and W. Thomlinson (NSLS 

Beamline X12B 

The Structure Determination of Murine Cytosolic Epoxide Hydrolase ........................ 

M. Argiriadi and D. Christianson (U. of Pennsylvania) 

X-Ray Structural Studies on OspB, an Immunogenic Outer Surface Protein of the Bacteria 

Borrelia burgdorferi, the Causative Agent of Lyme Disease. .................................... 

M. Becker, B. Lade, H. Kycia, J.J. Dunn, C.L. Lawson (BNL) and B.J. Luft, (SUNY 

at Stony Brook) 

X-Ray Structure of A Six-Finger TGIIIA-DNA Complex ...................................... 

R.S. Brown, R. T. Nolte, R.M. Conlin and S. C. Harrison (HHMI, Children's 

Hospital Harvard U.) 

Real-Time Small Angle X-ray Scattering Study of Isotactic Poly(propy1ene) .................... 

P. Dai, G. Georgiev, and P. Cebe (Tufts U.),and M. Cape1 (BNL) 

Mechanical Behavior of Novel Block Copolymer Morphologies ................................. 

B.J. Dair (MIT), E.L. Thomas (MIT), M.C. Cape1 (NSLS) 

Glutamine Synthetase from Mycobacterium Tuberculosis: Aim Toward Drug Discovery ......... 

H. Gill and D. Eisenberg (UCLA) 

2.1 A Structure of the Complex Between Active Ras and The Ras-Interacting Domain 

of an Effector RalGDS ........................................................................ 

L. Huang, F. Hofer, G.S. Martin, and S-H. Kim (U. California at Berkeley) 

Vancomycin-Ligand Complex Structures ...................................................... 

P.J. Loll (U. of Pennsylvania) 

The Crystal Structure of the DNA Binding Domain of the Orphan Nuclear Receptor 

NGFI-B Complexed to its DNA Target at 2.7 .& ............................................... 

G. Meinke, P. Sigler (Yale University) 

Structure Determination of Mitochrondrial Cytochrome bcl Complex .......................... 

D. Xia, H. Kim, J. Deisenhofer (HHMI and U. of Texas SW Med. Center), C. A. Yu, 

A. Kachurin, L. Zhang, and L. Yu (Oklahoma St. U.) 

Beamline X12C 

Structural Studies on the Complex of the C-terminal Domain of Outer Surface Protein B 

of Borrelia burgdorferi with a Bactericidal Fab. .............................................. 

M. Becker, B. Lade, W. Ding, J.J. Dunn, C.L. Lawson (BNL), J. Bunikis, 

A.G. Barbour (UC at Irvine), and B.J. Luft (SUNY at Stony Brook)

X-Ray Structual Studies on OspB, an Immimogcnic Outer Surface Protein of tlic Bacteria 

Borrelia burgdorferi, the Causat,ive Agent of Lymc Disease. .................................... 

M. Bccker, B. Lade, H. Kycia, J.J. Dmn, C.L. Lamon (BNL) and B..J. Luft. (SUNY 


MAD Studies of the Bactcriophagc PRDl Major Coat Protein, P3 ............................. 

S.D. Bcnson, R.M. Burnet,t (Tlic Wistar Instit.), J.K.H. Bi~lnford. and D.H. Bamford 

(U. of Helsinki) 

X-ray Structural Study of Lyrnc Bactcrinm Outer Surface Protrin A Complcxcd With a 

mAb LA2 Fah Fragment by h/lultiwavclcngth Anonlalolls Diffraction Experimrnt ............... B-I 07 

W. Ding, B.J. Lufts, X. Yang (SUNY at Stony Brook), J. J. Dunn. alld C.L. Lawson (BNI,) 

Crystallization and Analysis of Native and Derivative X-Ray Diffraction D>~til from Bovint. 

Milk Xanthinc Oxidasc ....................................................................... 

B. Eger, E.F. Pai (U. of Toronto), K. Madrid, K. hIcConvillc (Aastra. Ilic.), I

Characterization of Mo-Ta Films .............................................................. 

H. J. Holland, G. F. Foster (Corning, Inc), and T. R. Watkin (ORNL) 

Structural Determination of the Cso/Ge(lll) Interface via X-ray Diffraction ................... 

T. Kidd, H. Hong, T.-C. Chiang (U. of IL, Urbana-Champaign), R. D. Aburano 

(Cypress Semiconductor), and T. Gog (Argonne Nat. Lab) 

Anisotropic Behavior and a Second Length Scale in the Critical Diffuse Scattering from 

the Tricritical System V2H .................................................................... 

J. Trenkler, P. Chow, S. C. Moss (U. of Houston), R. Paniago (U. of Munich), J. Bai 

(U. of Illinois), and R. Hempelmann (U. des Saarlandes) 

High Temperature Residual Stress Measurement in Thermal Barrier Coatings .................. 

T. R. Watkins and C. R. Hubbard (ORNL) 

Beamline X15A 

Surface Structure of Zn2+ Adsorbed on Calcite (1074) Surface .............................. 

L. Cheng, M. Bedzyk (ANL and Northwestern U.), N.C. Sturchio (ANL), and 

J.C. Woicik (NIST) 

Polarity Determination of GaN Thin Films on Sapphire(0001) by X-ray Standing Waves ....... 

A. Kazimirov, G. Scherb, J. Zegenhagen (Max-Planck-1nst.-FKF, Germany), T.L. Lee 

(NWU), M.J. Bedzyk (NWU and ANL), M.K. Kelly, H. Angerer, 0. Ambacher (Walter- 

Schottky Inst., Germany) 

Dimer Structure of Sb-Terminated GaAs(001)-(2x4) Surface .................................. 

T.-L. Lee (Northwestern U.) and M.J. Bedzyk (Northwestern U. and ANL) 

Surface Structure of Te-Terminated Ge(001) ................................................... 

P.F. Lyman (Northwestern U.) and M.J. Bedzyk (Northwestern U. and ANL) 

In-As Layer Spacing in Buried InAs/GaAs(001) ............................................... 

J.C. Woicik and J.G. Pellegrino (NIST) K.E. Miyano (Brooklyn) P.F. Lyman 

and M. J. Bedzyk (Northwestern) 

In-Situ X-ray Standing Wave Analysis of Electrodeposited Cu Monolayers on GaAs(001) ....... 

J. Zegenhagen, G. Scherb, A. Kazimirov (Max-Planck-Inst . , Germany), H. Ngushi, 

K. Uosaki (Hokkaido U., Japan), T.-L.Lee (NWU), and M.J. Bedzyk (NWU and ANL) 

Beamline X15B 

Fundamental Limit Of Free-Carrier Densities In n-doped Si ................................ 

D. J. Chadi, C. H. Park (NEC), D. L. Adler, M. A. Marcus, H.-J. Gossmann, 

and P. H. Citrin (Bell Labs) 

Trace Metal Contaminants in Optical Silica Preforms .......................................... 

P. A. Northrup, R. M. Atkins, P. F. Glodis, D. C. Jacobson, and P. H. Citrin (Bell Labs) 

Structural Stability of Vacancy-Ordered Rare-Earth Fulleride .................................. 

K. M. Rabe (Yale) and P. H. Citrin (Bell Labs) 

Beamline X16A 

Formation of Copper Silicide using Surface X-ray Diffraction ................................ 

P. Bennett (ASU), I. Robinson and D. Walko (UIUC) 

Ultra-High Doping in Si(001): B Pairing and Diffusion ........................................ 

G. Glass, I. K. Robinson, D. Walko, and J. E. Greene (U. of Illinois) 

Irradiation Induced Strain Relaxation of a Metastable SiGe Film .............................. 

C. Kim, T. Spila, J. E. Greene and I. K. Robinson (U. of Illinois) 

Ion Implantation Damage in Semiconductors .................................................. 

P. J. Partyka, R. S. Averback and I. K. Robinson (U. of Illinois) 

X-ray Investigation of a Sio,9Geo,1(001) Single Crystal Surface ................................. 

H. Reichert (U. of Wuppertal, Germany), S.C Moss (U. of Houston), C.Y. Kim, 

and K. Evans-Lutterodt (Lucent Technologies)

Evoli~t,ion of 0-Indiiccd Facet Formation on Cu(115) ....................................... 

D.A. Walko and 1.K Robinson (Univ. of Illinois) 

Bearnline X16C 

Si~pcrstri~ctlirc Ordering in La Doped PAIN Single Crystals ................................. 

D. M. Fanniiig, S. T. Jiing. D. A. Paync. I. I .............................. 

A. I. Frcnkcl, M. S. Naslincr, J. R. Shaplcy. and R. G. Nllxxo (U. of Illiimis) 

XAFS Analysis of Particle Sixc Effect on Local Strlictiirc of BaTiO,{ ........................... 

A.I. Frcnltcl and D.A. Paps. (U. Illinois at Ur1,ana-Cliam~~aigil) 

Preparation and Characterization of Carbon Supportctl Pt-RII Nanoparticlc Ci\ti\ly~t~ ......... 

M.S. Nashncr, A.I. Frcnkcl. D.L. Adlcr. J.R. Shaplcy. and R .G. Niizxo (UIUC) 

X-Ray Microprol)~ Mcasiircmcnts of Pattenled InP ATulti-Qiiant~im \Ydl LRSC~S ............... 

E.D. Isaacs, K. Evans-Liittcrodt. R1.A. Rlarciis. A.A. hIacdo\vcll. I\'. Lrnliart, L..J.P. 

Krtclscn, J. Vandciihcrg, S. Splitx. J.E. John~on and J.A. Grcnko (Brll L~l)ori\t()ri~~) 

Bearnline X17B1 

Solind Velocity Measlircincnts at Si~iinltanroi~s High Prcsslirc and Tc~lllp~ri\tiirc For 

Polycrystallilio San Carlos Olivinc ........................................................... 

G. Clicii, Y. Sinelnikov, R.C. Licl~crma~~n (SUNY at Stony Brook) and G. D. 

Gwminrsia, K. Darling (DSU) 

Equation of State of NaCl From Sirniiltanco~is Ultrasonic and Syncllrotron X-ray 

Diffra.ction Meas~irciiiciits ..................................................................... 

G. Clicn, Y. Sinelnikov, M. T. Vallglian. and R. C. L~C~)S~III~IIII (SUiSY at Stony Brook) 

An Expcrimrntal Dcsign for Low Presslire and High Tcmpcratlirc ............................. 

J. Chcii (CHiPR, SUNY at Stony Brook) 

Following Olivine-Spiiicl Pl~asc Transition in Fayalitc wit11 TIPS ............................... 

J. Cllcn and D.J. Wcidiicr (CHiPR. SUNY at Stony Brook) 

Strcss Mcasiircnicnt of Anhydrous and Hytlrow phasc of Ringwoodit c, ......................... 

J. Clia~, D. J. Wcidncr, T. Inonc, H. Kagi and hI T. Valiglian (CHiPR. 

SUNY at Stony Brook) 

Rhcological Stlidy of Lower hlant,lc hlincrals. Pcrovskitc and Pcriclasc ......................... 

J. Cl~cn, D. J. Wcidncr, h?. T. Va~iglm~ and H. Kagi (SUNY at Stony Brook) 

Time R.csolvcd Diffract,ion hlcas~ircmcnt with an Iinagi~lg Plats at High Prrssiirc and 

Tonipcra.tnrc .................................................................................. 

J. Chcn, D. J. Wcidncr, hl. T. Valigllan, R. Li. J. B. Parisc. C. C. Kolcda 

ant1 K. J. Baldwin (CHiPR, SUNY at Stony Brook) 

Sound Wavc Velocity Mcasiircmcnts at High Presslire a1~1 T~n~pcratiirc for PoI\'~~.y~ti~lli~l~ 

MgSi03 Ortliopyroxcnr ....................................................................... 

L. Flcsch, B. Li, J. Z11ang. J. Cooks. R. Lichcrmann. and AT. Va~iglia~i. (CIHiPR. 


Comparison of Expcrimcnt~al Electron Spcctril with tllc Intcgratcd TIGER Scrics (ITS) 

Simul a t' I011 .................................................................................... 

N. A. G~~ardala, D. J. Land, J. L. Pricc (Naval Silrfacc \;lrarfi\rc Cciitn), Y. IITi~~fi. 

and G. A. Glass (U. Soi~t~lnvcstern Loliisana)

Elasticity of Polycrystalline Mg4Si4012 Majorite Garnet at P=9 Gpa and T=1000K in 

a DIA-Type Cubic-Anvil Apparatus Interfaced with Synchrotron X-rays ....................... 

G. Gwanmesia (DSU), G. Chen, J. Cooke, L. Flesch, R. Liebermann, and M. T. Vaughan 


The Crystal Structure of Bi4Au2014: The Use of a Siemens CCD Detector 

with Short-Wavelength Radiation ............................................................. 

R. Harlow (DuPont), J. Parise (SUNY at Stony Brook), J. Phillips and C. Campana 

(Siemens), and J. Hanson (BNL) 

Strength Measurements of Carbonado, A Natural Polycrystal Diamond. ....................... 

H. Kagi, J. Sweeney, J. Chen and D.J. Weidner (SUNY at Stony Brook) 

Direct Determination of Pressure-Temperature Paths in the Laser-Heated Diamond Anvil Cell . 

A. Kavner and T. Duffy (Princeton U.), G. Shen (CARS), D. Heinz (U. Chicago), 

and R. Jeanloz (U.C at Berkeley) 

High Pressure High Temperature Behavior of an Iron-Nickel Meteorite ......................... 

A. Kavner and T. Duffy (Princeton U.), G. Shen (CARS), and R. Jeanloz (U.C at Berkeley) 

Simultaneous Ultrasonic Interferometry and in-situ X-ray Studies on Wadsleyite (P-Mg2SiO4): 

P-V-Vp-Vs-T Measurements to 7 GPa 885K .................................................. 

B. Li, J. Liu, L. Flesch, R. C. Liebermann, J. Chen (SUNY at Stony Brook), and G. D. 

Gwanmesia (Delaware State U.) 

Simultaneous Ultrasonic Interferometry and in-situ X-ray Studies on Forsterite (MgaSiO4olivine): 

P-V-Vp-Vs-T Measurements to 8 GPa and 1300 K ................................... 

B. Li, J. Liu, L. Flesch, , R.C. Liebermann, J. Chen (CHiPR, SUNY at Stony Brook), 

Brian Savage (UC Berkeley) 

Thermal Equation of State of Stishovite ....................................................... 

J. ~iu,>. Zhang, L. Flesch, B. Li, D.J. Weidner, and R.C. Liebermann (SUNY at Stony Brook) 

Formation of a-eucryptite, LiA1Si04: An In-situ Synchrotron X-ray Powder Diffraction Study 

of a High Temperature Hydrothermal Synthesis ............................................... 

P. Norby (SUNY at Stony Brook), J. C. Hanson, L. Flaks, J. Hastings (BNL) 

Shear Wave Velocity of MgSi03 Perovskite up to 8 GPa and 400°C ............................ 

Y.D. Sinelnikov, G. Chen, J. Liu, D. Neuville, R.C. Liebermann, and D.J. Weidner (SUNY at 

Stony Brook) 

Thermoelastic Properties of CaTi03-CaSi03 Perovskites ...................................... 

Y. Sinelnikov, J. Zhang, R. C. Liebermann (CHiPR, SUNY at Stony Brook) 

Powder X-ray Diffraction for Anisotropic Compression Measurements at High Pressures ........ 

M. S. Somayazulu, Y. Z. Ma, J. Z. Hu, J. F. Shu, H.-K. Mao, R. J. Hemley 

(Carnegie Inst. Washington, CHiPr), M. Rivers (U. of Chicago), T. Duffy (Princeton U.) 

A High-Energy Diffraction Study of the Bulk Critical Scattering in a V2H Crstal .............. 

J.Trenkler, H. Abe, P. Chow, D. Scarfe, S. C. Moss (U. of Houston), P. Wochner, 

Z. Zhong, J. Hastings (BNL), R. Hempelmann (U. des Saarlandes) 

Equations of State of MgSi03 in the Sub-Perovskite Pressure Range ........................... 

M. T. Vaughan, E. K. Bell, and J. Z. Zhang (CHiPR, SUNY at Stony Brook) 

Use of Sintered Diamond Anvils in a 6-8 High-pressure Apparatus ............................. 

M. T. Vaughan, D. J. Weidner, J. H. Chen, and C. C. Koleda (SUNY at Stony Brook) 

Phase Transition in Zeolite A at 2 Kbars and 800" C Using SAM-85 ........................... 

Y. Wang (U. Chicago), J. Chen, F. Bejina, (CHiPR, SUNY at Stony Brook), M.C. 

Hash, L. Leibowitz, M. C. Petri, J. W. Richardson, Jr., ( ANL) 

Strength of the Subducted Slab: Implications for Deep Focus Earthquakes .................... 

D. J. Weidner, J. Chen, J. Ando, and Y. Wu (CHiPR, SUNY at Stony Brook) 

The Rheological Study of "Super Dry" Forsterite at High Pressure and Temperature ........... 

Y. Wu, D. J. Weidner, J. Liu, M. Vaughan and J. Zhang (CHiPR, SUNY at Stony Brook) 

Hard-X-ray Study of Single Crystal Superconducting LazCu04+b .............................. 

X. Xiong, D.P. Scarfe, S.C. Moss, A.J. Jacobson, W.J. Zhu, P.H. Hor 

(U. of Houston), P. Wochner (BNL)

Room Tmywratnrc Comprcssio11 of CdO ...................................................... 

J. Zhang (CHiPR, SUNY at Stony Brook) 

Comparative Co~npressil)ility of Calcite-Stn~ct~~rc Carl)onatcs ................................. 

J. Zllang and R. J. R~cdcr (CHiPR. SUNY at Stony Brook) 

Beamline X17B2 

Unidirectional P\/licrol)ca~n Radiatim Tlicrapy of Rat.; Bcariag Sl~l)cilta~~co~~s 91, 

Gliosarcoma T~~mors: Rclcvancc to Radiotlicrapy of Craniospil~al TIIIII~~S ill HIIIII~IIIS ..... 

F.A. Dilinanian. X.Y. WII. B. Rcn. A.Z. Dia7. RI. Kcrsl~an.. G. Lc DII~. 

D.T. Loinimrdo, P.L. Rlicca. RI.RI. Nan-rocky. D.N. Slatkin. F. Tc1a11g (BNI,), 

W.C. Thomlinson. Z. Zliong (NSLS). and ,J.C. Allcli (Bctli Israel RIcd. C'cwtcr) 

Xcnon K-rdgc Imaging With a RIonocliro~natic CT Scanner to Sclcrtiwly Ilnagc Fat in Rats: 

Rclcvailcc to Compositional Iinaging of Carotid Atl~crosclcrotic Pl;rqi~c~s ..................... 

F.A. Dilinanian, X.Y. WI, B. Rcn. X. Huang. D.N. Slwkin. (BNI,), \IT.C. Tl~onilil~wn. 

Z. Zliong (NSLS), T.hl. Button. RI..J. Pctcrscn (SUNY at Stol~y B~ook), and 

L.D. C11apman (ITT) 

Preliminary Expcrimcnts on a hlammograpliy Iniaging System alitl a RIl~lti-1,iiycr 

~o~iocliromator for Ai~giograpliy .............................................................. 

K. Hyodo, h4. Ando (PF), K. Tanioka. R. hlocliizitki (NHK). H. hlori (Tokai Univ.). 

Z. Zhong and W. Tliomlinson (NSLS) 

Dual-energy Subtraction Imaging Utilizing Indi1111i As a Contrast Agent ....................... 

G. Lc Duc, Z. Zliong. W. Tl~omlinson (NSLS), L. \Yarkcnticn. and B. Lilht~~ (BNI,) 

Contrast Analysis of 2D hl011ocl1ro1natic X-ray Coronary Artery I~iiagrs ....................... 

Y. O ~II (U. for Adv. Studies). Ii. Hyotlo. h1. A~itlo (KEK). Z. Zliong am1 

W. Tllolnliilson (NSLS) 

A Bcnt Law-Law Monochromator for the Rli~ltiplc Energy Conipi~trd Tomogrnpliy Project ... 

B. Rcn, F.A. Dihiianian. X.Y. UTu. X. Hmng (BNL). L.D. Cliaplnan. I. Ivirnov 

(CSRRI), and Z. Zl~ong (NSLS) 

Beam Harmonics In a Bent Lai~c-Law RIonocliromator ........................................ 

B. Rcn, F.A. Dillnanian. X.Y. M'II (BNL). Z. Zliorig (NSLS). L.D. CIia~man 

and I. Ivailov (CSRRI) 

Eiicrgy Rcspo~lsc h4easnrcn1cnts of Dcntal CCD Sensor Systems Using RIoiioclironi;~tic X-Rays . 

K. Tokumori, S. Iianda. F. Toyofitki~ (Iiy~lsl~n Univ.). K. Hyodo. RI. Aiido (IiEIi), 

Z. Zliong and W. Tllolnlinson (NSLS) 

Beamline X17C 

In, SSitl~. 

Itlcnt~ificat~ioii of Natilral Diamond Incl~lsions with Syl~cl~rotroi~ RIicrodiffr;~ctio~~ ... 

P. G. Conrad, R. J. Hcmlcy, H. I

Thermal Diffuse Scattering in Indium ......................................................... 

A. W. Overhauser, A. S. Bakulin and S. N. Ehrlich (Purdue University) 

Binding Energy of Aligned Glass on Thin Films of Liquid Crystals ............................. 

D. E. Silva, P. E. Sokol, J. S. Pate1 (Penn. State U.), and S. N. Ehrlich (Purdue U.) 

Chevron Structure in the Smectic-A Phase of the Liquid Crystal M24 ......................... 

D. E. Silva, P. E. Sokol, J. S. Pate1 (PA. State U.), and S. N. Ehrlich (Purdue U.) 

Competition Between Surfaces in Thin Films of Liquid Crystals ............................... 


Long-Range Order and Critical Diffuse Scattering from the Tricritical System V-H 

near the PI-P2-Phase Transition .............................................................. 

J. Trenkler, P. Chow, U. Klemradt, S. C. Moss (U. of Houston), D. Lott (NSLS), 

S. Ehrlich (Purdue U.), R. Hempelmann (U. de Saarlandes) 

Preferred Orientation and Anisotropy of Piezoelectric Materials ............................... 

Shan Wan and Keith J. Bowman (Purdue University) 

Structural Evolution of Li,MnzOe in Lithium ion Battery Cells Measured In situ 

Using Synchrotron X-ray Diffraction Techniques ............................................... 

X. Q. Yang, S. Mukerjee, X. Sun and J. McBreen (BNL) 

Anomalous Transmission of X-Rays in a Quasicrystal .......................................... 

Y. Zhang, S. N. Ehrlich and R. Colella (Purdue U.) 

Debye-Waller Factors in a Quasicrystal ........................................................ 

Y. Zhang, J. Sutter, S. N. Ehrlich and R. Colella (Purdue U.) 

Beamline X18B 

X-ray Absorption Study of Nickel in FCC Catalysts ......................................... 

S. R. Bare, A. Z. Ringwelski, F. S. Modica (UOP LLC) 

Characterization of a Si(Li) Detector for the SIXA Array ...................................... 

T. Tikkanen, K. Hamalainen, and S. Huotari (U. of Helsinki, Finland) 

Bond-length Distortions in Strained-semiconductor Alloys ..................................... 

J.C. Woicik, J.G. Pellegrino, and B. Steiner (NET) K.E. Miyano (Brooklyn U.) 

S.G. Bompadre and L.B. Sorensen (Washington U.) T.-L. Lee (Northwestern U.) 

S. Khalid (NSLS) 

Beamline X19A 

XANES Analysis of Ti-V-Silicalites .......................................................... 

S. R. Bare, A. Z. Ringwelski, F. S. Modica, L. Nemeth (UOP LLC) 

X-ray Absorption Spectroscopy of Cesium Modified Catalysts ................................. 

E.J. Doskocil and R.J. Davis (U. of Virginia) 

XANES Characterization of Soil Phosphorus .................................................. 

D. Hesterberg, W. Zhou, S. Beauchemin, and D. E. Sayers (NC State and Ag-Canada) 

In Situ Characterization of the Reduction of Rh/CexZrl-x02 ................................ 

S.H. Overbury, D.R. Huntley, D.R. Mullins (ORNL) and G. Glavee (Lawrence U.) 

Observation of a Novel 4-Layer Superlattice in a Smectic Liquid Crystal Using Anomalous 

Diffraction .................................................................................... 

R. Pindak (Bell Labs), A.M. Levelut (Orsay, France), P. Barois (CRPP), P. Mach 

(U. of Minnesota), and L. Furenlid (NSLS) 

Characterization of Sulfur Oxidation States in Soil Humic Acid ................................ 

W. Zhou, D. Hesterberg, K. Hutchison, and D. E. Sayers (NC State) 

Beamline X19C 

X-Ray Reflectivity of Polymeric Surfactants at the Air-Water Interface. ..................... 

A. S. Brown (Australian National U.), S. A. Holt (U. of New South Wales) and 

G. J. Foran (Australian National Beamline Facility)

Com1)incd SWBXT and HRTXD Stlldics on Drfcct Distri1)utions in 11-VI COIII~OIIII~ 

Sciniconth~ctors I. CtlZiiTc .................................................................... 

Y. Guo, H. Cl~llng, J. SII. M. Dlidlcy (SUNY at Stony Brook), H. Al. Volz. C. Sa11(~, 

and R.. J. Mat,yi (U. of Wisonsin-hladison) 

Comlincd SWBXT and HRTXD Stlldics on Dcfcct Distri1)utions in 11-VI Con~po~u~tl 

Scn~icontl~~ctors I1 ZilSc ....................................................................... 

Y. Guo, H. Cli~lng, J. SU, hl. D~ldlry (SUNY at Stony Brook), H. RI. Volz. C. Si111('~, 

and R.. J. Mat,yi (U. of Wisconsin-AI;ldison) 

Characterixat,ion of Dcfcct,s in SiC Drvicrs Using Synelirotroii \Yllitc. B('ilm X-rily Topogral)lly 

and Tllcir R.clat~ions11ip wit11 Device Pcrfor~~iancc .............................................. 

W. Huilllg, M. Dl~dlty (SUNY Stony Brook), P. Ne~~tlcck (NASA Lewis Rcr, Jr. (Cree Rcscarcll. he.) 

Tlic Liqllid-vapor Ilit,crfi~cc Strllct,~uc of Tin:C ?a 11' 111111 .......................................... 

N. Lei and S.A. Rice (U of Chicago) 

Gold Colloid Nano-St,rnct,~lres in Polymrr Thin Filnis .......................................... 

B. Lin, M. Mcron, and P..J. Viccaro (CARS-U. Cllicago). S. \Villia~ns and h1.L. 

Sclllossman (UIC), T. hlorkvcd, H. .Jacgcr, and Z. Hmng (JFI-U. Cllicago) 

Effcct of Const~raincd Growth on Dcfcct Strncturrs in RIicrogri~vity-G~OIVII C~ZIIT(> Bolll(~s I. 

N~iclcation of Grains .......................................................................... 

B. R.il~gl~ot~l~al~~~cl~~, 

H. Cli~mg, AI. Dlldlcy, D.J. Lars011 Jr. (SUNY at Stony nrook) 

Effect of Const,raiilcd Growth on Dcfcct Stn~ct~ircs in hlicrogri~vity-G~OIVII CtlZ11Tt. Bo~llos 11. 

Inhoinogcncoi~s St,rains ........................................................................ 

B. R.ixgl~ot,lial~~acl~ar, H. Chuig. RI. D11dlc-y. and D.J. Larson Jr. (SIJNY. Stony Brook) 

Effcct of Const,raincd Growtli on Dcfcct Stnlct~lrcs in hlicrogravity-G~OTVII CtlZnT(~ Bo11lt.s 111. 

Twins ........................................................................................ 

B. R.agl~ot~l~al~~achi~r, H. Cl~llng, AI. Dlldlcy, and D.J. Larson .Jr. (SUNY. Sto~~y Brook) 

Stltdics on Int,crfacc Demarcation in Bridgman-Stock1)argrr Grown CtlZnT(~ Singlv Cryst ills 1)y 

SWBXT ...................................................................................... 

B.R.aghot~hamac1iar, hI. Dlldlry, and D..J. Larson Jr., (SUNY. Stony Brook) 

Cl~i~~r;lct,crizatio of Twinning Operations in PVT Grown CtlTc Singlc Crystals 1)s SM7BXT .... 

B. R.agl~ot~l~ain;lcll:~r, 11. Dlldl(,y (SUNY, Stony Brook). \V. Palosz. D. C. Gillics 

(NASA Marshall Space Flight Ccntrr) 

La.l~lclli~.r Twinning in p-Quatcrplmlyl Crystills ................................................ 

William M. Vct,t,cr and Rlicliacl Dlltllcy (SUNY Stony Brook) 

Mi~.croscopic Twiimi~lg ill 1)-Q11atcr~11(~11?-1 Crystills ............................................ 

W.M. Vct,t,cr and hI. Dlldlcy (SUNY at Stony Brook) 

Surfa.cc Sca.t,tcring From tlir C.,EI Oil-hlicrocini~lsim Intcrfi~~c ................................ 

S. M. Williams, Z. Zllilllg. D. hl. RIitrinovi6. hI. L. Scl~lossman (U. of 11, 

at Chicago), and Z. H11i111g (BNL) 

Silrfacc Sca.t,tJcring from tlir CloE4 Oil-Rlicrorni~~lsim Intrrfacc ................................ 

S. M. Williiims, Z. Zlliulg D. hi. Alitriilovic. 11. L. Scldossi~lan (U. of IL ;~t Chicago), a11c1 

Z. Hua.ng (BNL) 

X-riv R.cflcctivity From a 1,1,2.2 Tctraliydrol1ci~icosafl11oro~1o~1~~~11o Alo~loli~;\.cr at t11c 

Wa.tcr-Hcxanc Int,crfacc ....................................................................... 

Z. Zhang, S.M. Williams, D.RI. AlitriaoviC. N.L. Sc11loss111a11 (U. of Illillois 

at Chicago), and Z. Hllang (BNL)

X-ray Reflectivity from the Water-Hexane Interface ........................................... 

Z. Zhang, S.M. Williams, D.M. Mitrinovic, M.L. Schlossman (U. of Illinois 

at Chicago), and Z. Huang (BNL) 

Beamline X20A 

Kinetics of Monolayer Electrodeposition ...................................................... 

A.C. Finnefrock, K.L. Ringland, L.J. Buller, H.D. Abruiia, J.D. Brock (Cornell U.) 

The Dynamic Evolution of Charge-Density Waves ............................................. 

K.L. Ringland, A.C. Finnefrock, Y.P. Li, S.G. Lemay, R.E. Thorne, J.D. Brock (Cornell U.) 

Atomic Structure of the Passive Oxide Film Formed on Iron ................................... 

M.F. Toney (IBM Almaden Research Center), A. J. Davenport (UMISTIU. Manchester) , L. J. 

Oblonsky and M.P. Ryan (BNL) 

X-Ray Diffraction Studies of CoPtCr Thin Films for Magnetic Recording Media ............... 

M.F. Toney (IBM Almaden Research Center) and M.F. Doerner (IBM) 

X-ray Scattering Studies of Thin NixCol-,, x z 0.25 Films: Discovery of a Reentrant 

Phase Transformation 

......................................................................... 

M.F. Toney and D. Weller (IBM Almaden Research Center), and A. Carl 

(Gerhard-Mercator U. Duisburg) 

Beamline X20C 

Small Angle X-ray Scattering from Silica Aerogels .......................................... 

L.B. Lurio, A.R. Sandy, S.G.J. Mochrie (MIT), N. Mulders and M.W.H. Chan 

(Pennsylvania State U.) 

Phase Formation Sequence of Nickel Silicides from Rapid Thermal Annealing of Ni on 4H-Sic . . 

L.D. Madsen (Uppsala U. and U. of Illinois), E.B. Svedberg, H.H. Radamson 

(Linkoping U., Sweden), C. Hallin (Link"ping U. and ABB Corp. Research, Sweden), 

B. Hjorvarsson (Uppsala U., Sweden), C. Cabral, Jr., J.L. Jordan-Sweet and C. Lavoie (IBM) 

X-ray Scattering Study of Ordering Kinetics in CuAu ........................................ 

0. Malis and K. F. Ludwig (Boston U.) 

Determination of Polymer Chain Orientation in Rubbed Polyimide Films .................. 

J. Sands (Pennsylvania State U.) 

Beamline X21 

X-Ray Resonant Raman Scattering Study at the Nd L3 Edge on Nd2Fe14 .................. 

F. Bartolomk, J. M. Tonnerre, L. Skve, D. Raoux (CNRS), and C-C. Kao (BNL) 

Inelastic X-ray Scattering from Single Crystal Sodium and Lithium ............................ 

P. Chow (U. Houston), J.P. Hill (BNL), C.-C. Kao (NSLS), and B.C. Larson (ORNL) 

The Evolution of the Cu KP1,3 Spectrum From Threshold ..................................... 

M. Fritsch, M. Deutsch (Bar-Ilan U., Israel), and C.C. Kao (NSLS) 

High Resolution Inelastic Scattering Study of GaN ............................................ 

K. Hamalainen, S. Huotari, S. Manninen (U. Helsinki, Finland), and C.-C. Kao (NSLS) 

Resonant Inelastic Scattering in Nd2CuOa .................................................... 

J.P. Hill, C.-C. Kao, W.A.C. Caliebe (BNL), M. Mastubara, A. Kotani (ISSP, Tokyo), 

J.L. Peng and R.L. Greene (U. Maryland, College Park). 

Impact of Band Structure and Many-Body Effects on the Electronic Response of a Simple 

Metal Al) ..................................................................................... 

B. C. Larson, J. Z. Tischler (ORNL), A. Fleszar (U. of Wurtzburg), and 

A. G. Eguiluz (U. of TN & ORNL) 

Inelastic X-ray Scattering around the Metal-Insulator Transition in VO2 ....................... 

0. Muller, P. Pfalzer, M. Klemm, S. Horn (Univ. Augsburg, Germany), M. L. denBoer 

(Hunter College CUNY)

Electronic Excitations in Solid CFO 1)y I~iclastic X-Ray Scattering .............................. 

P. W. Stcplicns, S. Zwcrsclikc (SUNY at Stony Brook). H. Bcrgcr (Swiss Fcdt~ral Instit~~tcl 

of Tcclinol, Lallsannc), and C.C. Kao (KSLS) 

Bearnline X22A 

Structure of Electrode Surfaces in the Course of Elcctrocatalytic: Br/AU(100) iml 

Ag/Pr(lll) During the Colirsc of O2 ....................................................... 

R..R.. AdRii. and J.X. Wang (BNL) 

X-R.ay Scattering Stlldy of the Calcite-\Vatu Intcrf;~cc: Snrfacc Strl~ct~uc and hlvtal 

Adsorption ................................................................................... 

P. Geisshiihler, D. Yec, L.B. Sorcnscn (U. RTashington. Seattle). P. Fciitcr, N.C. 

Stmchio (ANL), and E. DiR'lasi (BNL) 

Dcptli-Dcpcndcncc of Strains in Cii Films on AlN ............................................. 

L. J. Martkcz-hlIirandR: Y. Li (U. of hlaryland. Collcgc Park). L. I

The Surface Structure of Ferrocenyl Surfactants ..................................... : ......... 

H. Kraack (Bar-Ilan U., Israel), V. Craig, N. Abbott (UC Davis), B. Ocko (BNL), 

X.Z. Wu (IBM Almaden), and M. Deutsch (Bar-Ilan U.) 

Structural Properties of Gramicidin A at the Air/Water Interface .............................. 

H. Lavoie, C. Salese, D. Ducharme (U. of Quebec), D. Vaknin (Ames Lab), and 

B.M. Ocko (BNL) 

In-Plane Depth Profile Sudies of Strain in PZT and PLZT Thin Films ......................... 

Yiqun Li, A. Dhote, S. Aggarwal, R. Ramesh, and L. J. ~artlnez-Miranda 

(U. of Maryland at College Park) 

X-Ray Reflectivity of Diblock Copolymer Monolayers at the Air/Water Interface ............... 

Z. Li, W. Zhao, J. Quinn, M.H. Rafailovich, J. Sokolov, (SUNY at Stony Brook), R.B. 

Lennox, A. Eisenberg (McGill U.), X.Z. Wu, M.W. Kim, S.K. Sinha (Exxon Research 

& Engineering Co.), and M. Tolan (U. of Kiel, Germany) 

Depth-Dependence of Strains in Cu Films on A1N ............................................. 

L. J. ~artinez-~iranda, Y. Li (U. of Maryland, College Park), L. K. Kurihara, P. 

Schoen, and G. M. Chow (NRL) 

X-Ray Reflectivity Studies of Alkanethiol Coated Gold Nanoparticles .......................... 

B. Ocko, D. Nguyen (BNL), C. Clarke, B. Lennox (Mcgill U.), Z. Li (Exxon), 

M. Rafailovich and J. Sokolov (SUNY at Stony Brook) 

Electrodeposited Bromide on Ag(ll0); Phases and Phase Transition ........................... 

B.M. Ocko, J.X. Wang (BNL), and T. Wandlowski (U. of Ulm & Munich) 

X-ray Reflectivity Studies of Phospholipids .................................................... 

A. Saxena, B. Ocko, D. Nguyen (BNL), C. Clarke (McGill U.), Z. Li (Exxon Research 

and Engineering), M. Rafailovich, J. Sokolov, and 0. Bahr (SUNY at Stony Brook). 

In-situ X-Reflectivity Measurement of Alkylthiolate Formation of Ag Ions and Alkythiol 

Mmonolayer at the H20/Air Interface ......................................................... 

K. W. Shin, M. Rafailovich, J. Sokolov (SUNY at Stony Brook), Z. Li (Exxon Res.& Eng.), 

A. Gibaud (U. du Maine Faculte des Sciences, France), M. W. Kim (KAIST, Korea) and 

Y.T. Kim (Yonsei U., Korea) 

The Structure of Polyelectrolyte Block Copolymers in Water/Butanol Mixtures ................ 

K.W. Shin, M. Rafailovich, J. Sokolov (SUNY at Stony Brook), D. Nguyen (BNL), 

Z. Li (Exxon Res. & Eng.), A. Gibaud, G. Vignaud (U. du Main Faculte des Sciences), 

J. Cox, and A. Eisenberg (McGill U., Canada) 

Beamline X22C 

Magnetic and Structural Measurements of Substrate-Matched Erbium Films ................. 

G. Helgesen (IFE, Norway), D. Gibbs (BNL), M.J. Conover, and C.P. Flynn (U. of Illinois) 

Incommensurate Magnetism In PrBa2 C U ~ ................................................ 

~ ~ . ~ ~ 

J.P. Hill (BNL), A.T. Boothroyd (U. Oxford), N.H. Andersen (Risoe), E. Brecht and T. 

Wolf (Forschungszentrum Karlsruhe) 

X-Ray Resonant Exchange Scattering Studies of Magnetic Structures of EuNi2Gea Single 

Crystal in Zero Applied Magnetic Field ....................................................... 

Z. Islam, C. Detlefs, A.I. Goldman, S.L. Bud'ko, P.C. Canfield (Ames Lab.), J.P. Hill 

and D. Gibbs (BNL) 

Structure and Temperature Dependence of Truly Clean Ru(0001) .............................. 

V. Jahns, A.P. Baddorf, D.M. Zehner (ORNL), and D. Gibbs (BNL) 

Surface Relaxation on the Clean and Hydrogen Covered Ru(001) Surface Measured By X-ray 

Diffraction .................................................................................... 

V. Jahns, A.P. Baddorf, D.M. Zehner (ORNL), and D. Gibbs (BNL) 

Structure and Phase Behavior of Ir(001) .................................................... 

V. Jahns, D. M. Zehner (ORNL), G. Watson (UMBC, BNL) and D. Gibbs (BNL)

Ma.gnctic Stxuctl~rcs and Plli\s~ Tra~~sitions of U(Asl-,Sc,,.) Solid Solntions .................... 

M.,J. Longfiold, W.G. Stirling (U. of Liverpool. UK), E. Lidstrom (ESRF. Frn~lco 

and EITU, Germany) and G.H. Lander (EITU, Grrmany) 

Orbital Ordering in a Cnl)ic Perovskitc ........................................................ 

Y. Mura.kami, I. Koyama, ill. Tanaka (KEK). .J.P. Hill. D. Gii)l)s and hI. Bl~~mc (BNL) 

Structure and hiIagnctis~ii of EuBG ............................................................ 

S. Siillow, M.C. Aronson (U. of hlicliigitn). .J.L. Sarrao. Z. Fisk (NHAIFL). A. Vip,li;r~itc~, 

and D. Gi1)l)s (BNL) 

Real-time Relaxation of tllc Cll/R11(001) Intcrfacc Dliring Gron-tli ............................. 

H. ajonz, D. Gihl~s, (BNL), V. Jal~ns. A.P. Badtlorf and D.RI. Zclmcr (ORNI,) 

Beamline X23A2 

In sitn~, X-ray Ahsorption St~idics of Elcctrodcpositcd Thin Films ............................ 

M. Balasnhramanian and C. A. hldcndrcs (ANL) 

Processing of Pure-Pliasc hlnZn-Fcrrit,c Using Higli-Energy Ball hlillil~g: A11 X-Ray A1)soq)t ion 

Fine Stnlcturc Study ......................................................................... 

D.J. Fa,t,cmi, V.G. Harris (NRL), and J.P. Kirklatid (SFA) 

NEXAFS St~idics of RII in tlic Ternary Sk~idtlcr~iditc RII~.~P~~~.~SI~:~ 

........................... 

V.G. Harris (NRL), G.S. Nolas (hlarlow Iildl~strics). G.A. Slack (RPI), and T.hI. Trit t 

(Clcmsoll U.) 

XAS St~~dics of Prcfcr~nt,ii~l Site Distri1)ution of Ta and Pt in CoCr-Based Films ............... 

K. M. Kemncr (ANL), V. G. Harris, 14'. T. El;um (NRL), Y. C. Fclig. D. E. Li~llglili~~ 

(CMU), J. C. Woicik (NIST), and J. C. Loddcr (Rlcsa Rcscarch Iiistit~itc) 

XAFS Studies of tlic Aging of Soils Contaminatrd \iTitll Etllylclic Di1)ronlitlc .................. 

K. M. Kemncr and S. T. Pratt (ANT,) 

EXAFS Study of AlGaN Fihns ................................................................ 

K.E. Miyano (Brooklyn College), J.C. Woicik. L.H. Rohilis. C.E. Boiilili~~ (NIST). i111d 

D.K. Wickcndcn (,Johns Hopkins) 

Structure and Cllcmistry of FcS2 Battery Cathodcs ............................................ 

E. Stmnss, D. Golodnitsky, E. Pelcd (Tcl Aviv U.) S. Kostov, h3. L. dcnBorr, and S. G. 

Grecnl~lli~~l (CUNY, Hmtcr Collcgc) 

Phase-correct Bond Lengt,lis in Crystallillc GcSi Alloys ........................................ 

J.C. Woicik (NIST), K.E. Rliyano (Brooklyn Collcgc). C.A. King and R.\V. .J01111so11 

(Lnccnt), J.G. Pellcgrino (NIST), T.-L. Lrc (Nortlm-cstcrn), Z.H. LII (NRC) 


Thc Relationship Bctwccn hlicrostrlictwc Dcvclopnlcnt in Hydri~ting Ccll~clit ~ 1i1 thr 

Morphology of Silica F~unc Additives ........................................................ 

A.J. Allcn (NIST) and R .A. Livingston (FHIYA) 

Exploring thc Pcrformallcc Limits of a Bonsc-Hilrt Do11l~l~-Crysti~1 Ultra-S11iall-A1ig1C X-Ray 

Scilttcring Camcra ............................................................................ 

A.J. Allen and G.G. Long (NIST) 

Morphology of Polyctliylcnc/C;~rl~oil Black Composites ........................................ 

G. Bcancagr, S. Ri111c. D. Mr. Scharfcr (U. Cinn.) I

Small-angle X-ray Scattering Study of the Formation of Colloidal Silica Particles From 

Alkoxides: Primary Particles or Not? ........................................................ 

H. Boukari (U. Maryland & NIST), M. T. Harris (U. Maryland) & J. S. Lin (ORNL) 

The Effects of Hydrogen Peroxide and Sterilization on the Structure of 

Ultra-High-Molecular-Weight Polyethylene .................................................... 

M. Goldman, R. Gronsky, L. Pruitt (U. of C., Berkeley) and G. G. Long (NIST) 

Ultra-Small Angle X-Ray Scattering by Single-Crystal Aluminum Deformed In Situ ........... 

L. E. Levine, G. G. Long and R. Thomson (NIST) 

Use of Ultra-Small-Angle X-Ray Scattering to Measure Grain Size of Styrene-Butadiene 

Block Copolymers ............................................................................ 

R. T. Myers, R. E. Cohen (MIT) and A. Bellare (Harvard U.) 

X-ray Topography of Superalloy Single-Crystal Castings ....................................... 

R. Napolitano, R. Schaefer and D. R. Black (NIST) 

Particle Sizes and Size Distributions in Additives to Polymeric Systems ........................ 

K. C. Sheth and Y. Gao (GE R&D) 

Beamline X23B 

Characterization of an Er LIII Bragg Polarizer Grown by Molecular Beam Epitaxy ......... 

J. 0. Cross, B. R. Bennett, M. I. Bell (NRL) and K. J. Kuhn (Intel Corp.) 

Sample-angle Feedback For Improved Reproducibility in Diffraction Anomalous Fine-structure 

(DAFS) Spectra .............................................................................. 

J.O. Cross, W.T. Elam, V.G. Harris (NRL), J.P. Kirklans (SFA), C.E. Bouldin 

(NIST) and L.B. Sorensen (U.W.) 

EXAFS Study of the Local Structure Around Mn in Annealed ZnS:Mn Nanocrystals ........... 

J.O. Cross, W.T. Elam, D. Hsu, H.F. Gray, J. Yang, M. Smith and B.R. Ratna (NRL) 

DAFS Study of the Interfaces of an Fe/Si Multilayer .......................................... 

J.O. Cross, V.G. Harris, W.T.Elam (NRL) and M. Newville (U. Chicago) 

Quantitative Speciation of Cr at ppm Concentrations Using Chemometric Modeling of XANES 

Spectra 

....................................................................................... 

J.O. Cross, R.E. Shaffer, W.T. Elam, S.L. Rose-Pehrsson (NRL) and J.P. 

Kirkland (SFA, Inc.) 

Processing of Pure-Phase MnZn-Ferrite Using High-Energy Ball Milling: An X-Ray Absorption 

Fine Structure Study ......................................................................... 

D.J. Fatemi, V.G. Harris (NRL), and J.P. Kirkland (SFA) 

EXAFS Measurements of Non-Superconducting PrBa2CusOs,9: Evidence against Ba Site Pr 

Substitution 

.................................................................................. 

V.G. Harris, D. J. Fatemi, V.M. Browning, M.S. Osofsky, (NRL), and T.A. Vanderah (NIST) 

Magnet to Volume Effects in R2Fe17-,Al,N, (R=Er,Pr) Compounds Studied via EXAFS ...... 

V.G. Harris, D.J. Fatemi, (NRL), K.G. Suresh, and K.V.S. Rama Rao, (India Institute of 

Technology) 

XAS Studies of Preferential Site Distribution of Ta and Pt in CoCr-Based Films ............... 

K.M. Kemner (ANL), V.G. Harris, W.T. Elam (NRL), Y.C. Feng, D.E. Laughlin (CMU) 

J.C. Woicik (NIST), and J.C. Lodder (Mesa Research Institute) 

Structure and Chemistry of FeS2 Battery Cathodes ............................................ 

E. Straus, D. Golodnitsky, E. Peled (Tel Aviv U.) S. Kostov, M. L. denBoer, and S. G. 

Greenbaum (CUNY, Hunter College) 

Beamline X24A 

XSW Determination of the S/Au Interface Structure in SAMs .............................. 

P. Fenter (Princeton U., & ANL), F. Schreiber and G. Scoles (Princeton U.), L. Berman 

(NSLS), P. Eisenberger (Columbia U.), and M. J. Bedzyk (Northwestern, & ANL)

X-ray Standiiig Wave Dctcrn~ination of Qumt~im \Ydl Pcrfcction .............................. B-209 

J.A. Gupti~, E.D. Crozier, S.P. \;lTatkiiis (SFU) J.C. \IToicik. J.G. Pclltyyino (NIST). 

and K.E. Miyailo (Brooklyn College) 

X-ray Standiilg Wave Investigation of Hg/Ni(100) ............................................. B-210 

D. Hcsltctt, J. Wi~n~cr (Univ. of Rliodc Island), L.E. Bc~rman (NSLS-DNI,), alltl P.A. 

Dow1)cn (Uiiiv. of Ncl~raska-Lincoln) 

X-ray Standing Wave Mci~silrtli~c~lt~ from a 5-Fold Sy~nmcntry Rcflrctio~i ill tliv Ql~;~sicryst;~l 

A ~ P ~ ...................................................................................... M ~ ~ 

n-2 

T. Ja.ch (NIST), R.. C01l~li1 (Pmdw), A. I. GO~~IIIRII. T. LO~KISSO. ~11d D. Dt'li\~i('y (Ai~ios Ili11)) 

Grazing I~lcidciicc X-Ray Pliotocmission Spectroscopy of Si02/Si .............................. 

T. Jaeh and J. Gorillley (NIST) 

Argon Photoion Charge State Distri1)utions ................................................... 

L. Pibidi~, R. Wchlitz, J. Levin. and I. Sellin (U. Tennessee at I

Crystallographic Studies on the Nudix Proteins: The Gene Product of the E. coli Orf209 ....... 

S.B. Gabelli, M. A. Bianchet, S.F. O'Handley, M. Bessman, L. M. Amzel (JHU) 

Structure Of a Cre Recombinase-DNA Site-specific Recombination Synapse .................... 

F. Guo, D. N. Gopul, and G. D. Van Duyne (U. of Penn.) 

The Cu~a?,, Hypersatellites and Correlated Hypersatellites ................................... 

K. Hamalainen, S. Huotari (Helsinki U., Finland), C.C. Kao (NSLS) and M. 

Deutsch (Bar-Ilan U., Israel) 

Resonant X-ray Magnetic Scattering From an Fe/Gd Multilayer ............................... 

H. Hashizume, N. Ishimatsu, 0 . Sakata (Tokyo Inst. of Tech., Japan), N. Hosoito 

(Kyoto U., Japan), T. Iwazumi (KEK, Japan), K. Namikawa (Tokyo Gakugei U., Japan), 

and L. Berman (NSLS) 

2.1 A Structure of the Complex Between Active Ras and The Ras-Interacting Domain of an 

Effector RalGDS .............................................................................. 


Structural Studies of the IgE Fc Receptor ..................................................... 

T. Jardetzky (Northwestern U. ) 

The Structure of Liquid Boron ................................................................ 

S. Krishnan (Containerless Research, Inc.), J. J. Felten (CRI), S. Ansell, K. J. Volin, 

and D. L. Price (ANL) 

Levitation Apparatus for Structural Studies of High Temperature Liquids Using Synchrotron 

Radiation 

..................................................................................... 

S. Krishnan, J. J. Felten, J. E. Rix, J. K. R. Weber, P. C. Nordine (Containerless 

Research, Inc.), M. A. Beno, S. Ansell, and D. L. Price (ANL) 

Resonant Exchange Scattering in a Co/Ir Superlattice ......................................... 

M. B. Salamon and K. O'Donovan (U. Ill.) and E. Kita and H. Yanagihara (U. Tsukuba) 

Structural Studies of Gene 5 Protein-ss DNA Complexes ...................................... 

T. C. Terwilliger, R. G. Nanni (LANL) 

Structure Determination of Leukotriene A4 Hydrolase ......................................... 

M.M.G.M. Thunnissen, P. Nordlund (Stocklholm U., Sweden.), and J. Z. Haeggstrom 

(Karolinska Institute, Sweden) 

X-ray Studies of the Surface Wetting Transition in Liquid Ga-Bi .............................. 

H. Tostmann, P. S.Pershan (Harvard U.), E. DiMasi, B. M. Ocko (BNL), and M. 

Deutsch (Bar-Ilan, Israel) 

Surface Structure of Liquid Indium ............................................................ 

H. Tostmann, P. S. Pershan, 0. G. Shpyrko (Harvard U.), E. DiMasi, B. M. Ocko (BNL), 

M. Deutsch (Bar-Ilan, Israel) 

Non-Brownian Dynamics of Concentrated Colloidal Suspension Probed by X-ray Intensity 

Fluctuation (XIFS) ........................................................................... 

0. K. C. Tsui and S. G. J. Mochrie (MIT) 

Statistical Analysis of X-ray Speckle at X25 ................................................... 

0. K. C. Tsui, S. G. J. Mochrie (MIT), and L. E. Berman (BNL) 

High Resolution Data Collection and Structure Refinement of Mitochondria1 Cytochrome 

bcl Complex ................................................................................. 

D. Xia, H. Kim, J. Deisenhofer (HHMI & U. of Texas), C. A. Yu, A. Kachurin, L. Zhang, 

and L. Yu (Oklahoma St .U.) 

Structure and Action of Chaperonin: Structure Determination of GroEL/GroES Complexes .... 

Z. Xu, A. Horwich, and P. B. Sigler (Yale U. & Howard Hughes Medical School) 

Refinements to the Two-Beam Diffraction Interference Technique .............................. 

Y. Yacoby (Hebrew U.), H. Baltes, R. Pindak, L. ~feiffer,-R. Hamm (Bell Labs), R. Clarke 

(U. of Michigan), and L. Berman (NSLS) 

Structures and Oxidation States of Layers on Platinum Single Crystal Surfaces 8 ................ 

H. You, J. Tanzer, Y. Chu, and Z. Nagy (ANL)

Beamline X26A 

Partitioning of Ferric and Fcrro~~s Iron Bctwcc~i Coexisting Rlafic Silici~tc~ from Atliroi~tlack 

Meta,inorpliic Rocks ......................................................................... 

P.D. Crowlcy, R..E. Stainski (Amherst), hl.D. Dyar (\Yest Cllrstcr U.), R..J. Nrvlr. 

J.S. Dclancy (Rutgers U.), A.G. hlondcrs, S. Jin Young (\Yl~iti~iai~). H.A. Gl~rtsel~on. 

(Carleton), E.D. Gutniann, (Williams), D.F. Harri~igton. R. Graham (U~~ion), 

M.B. Chcrvasii~, (Collcgc of \Voostcr), S.R. S~tton alld G. Sl~ca-RlcCi~rtlly (U. CJl~i~i~go) 

Coordi~iation Effect 011 Fe Prc-edgr SmX Spccra of Garnrt .................................... 

P.D. Crowlcy, R..E. Stamski (Ainhcrst), A1.D. Dyar (\l'rst Clic~strr U.). R..J. Nc~vlc, 

J.S. Delailcy (R,utgcrs U.), H.R. hlorrison. h1.B. Clicrvasii~. (College of \\hostcr), Z.hI. 

Brown (SUNY at Buffalo), A.G. hlondcrs (\lTliit~i~an), D.F. Harrington. H.A. G~~c~tscl~ow 

(Carleton), E.D. G~t~mann, (MTilliams), S.R. Sutton and G. Sll~il-hI~Ci~rtI~!' (U. Cl~i~ilg~) 

Ferric/Fcrrous Microanalyses of Geological Glassrs 1,y Synclirotro~i hIicroXANES (SmX) ....... 

J. S. Delmcy (R,ut,gcrs U.), S. Bajt (LLNL), S. R. Sutto~i (U. Cliicago). 

and M. D. Dyar (MTcst Chester U.) 

R.cdox Ra.tios with Outragcol~s Resolution: Solving an Old geological Pro1)lcw with tllc' 

Syilchrotron MicroXANES Prolw ............................................................. 

J.S. Dclancy (R,utgcrs U.), h4.D. Dyar (\T7cst Cllcstcr U.), S.R. Suttm (U. Cliicago), 

and S. Bqjt (LLNL) 

The Sp~ct~roscopic Charact,crization of U in an Evaporation Bitsin Scdimrnt. LA-IJR-97-3589 ... 

M.C. Duff (LANL), D.B. Huntcr. P.hI. Bcrtscli (SRELIUGA). C. Amrl~c~ii~ (UC itt 

Riverside), D.E. Morris (LANL), G. Sllca-hIcCarthy (U. of Cliicago) 

Factors Iiifll~cncing U RC~OX P~OCCSSCS in Saline, Calrarcous Scdimcnts. LA-TJR-97-3590 ....... 

M.C. Duff (LANL), D.B. Hunter, P.M. Bcrtscll (SREL). C. Ainrl~cin (UCR), 

G. Shca-McCitrtliy (U. of Chicago) 

R.cdox Spccia.tjion of Cr in Conta~ninatcd Soils. LA-UR-97-3591 ................................ 

M.C. Duff (LANL), D.B. Hlmtcr, P.M. Bcrtsch (SREL). P. Longmirc (LANL), 

S. Klmg (LANL), G. Shra-NcCartliy (U. of Cliicago) 

Chemical A1~1lysis of Interplanetary Dust Particlcs ............................................ 

G. J. Flynil (SUNY at Plattsbnrgli), and S. R. Sutton (U. of Chicago) 

Clicmical Ana.lysis of Particle Capt~~rc Cells Flo~vn on tlir hIIR Space Stiltioii .................. 

G.J. Flynil (SUNY at Plat~tshurgh), S.R. Slittoil (U. of Cl~icago). T. B111ic (NASA A111c.s) 

Cllcmicd Analysis and Fc-XANES hlcas~ircmcnts on tlic ALFI8.1001 hIi~rs Rlrtroritc ........... 

G. J. Flynn (SUNY at Plwttsl)lirgli), S. R. Sutton (U. of Cliicilgo), L. P. Iicllt~ (hIVA 

Inc.), and J. S. Dclancy (Rutgcrs U.) 

Tlic Dist,ril)~~tion of Zinc in Cliondr~ilcs of Primitive h1ctroritc.s ................................ 

G. Hcrzog, C. Sclinal)cl, and J. S. Dclancy (Rutgcrs U.), G. J. Flynn (STJNY at 

Pla.tttfsh~~rg1i), and S. R. Sntton (U. Chicago) 

In Situ Investigation of Alloy Eltmcnt Bcliavior During Localizrd Corrosioi~ ................... 

H.S. Isa.acs (BNL- DAS), hl. Kancko (Nippon Stccl Corp.. Japan) 

Salt La.ycrs Formation oil St,ainlcss Stccl During Localizctl Corrosion ........................... 

H. S. Isaacs (DAS-BNL) and hl. Kancko (Nippon Strrl Corp., Ji~pal~) 

E1emc1lt~a.l Analysis of Drcdgctl hlatcrial From tlic Port of New York/Ncw Jrrscy Using 

Synchrotron R,adiat,ion-indl~ct'd X-ray Emission (SRIXE) ...................................... 

K. Jones (BNL) and S.-R. Song (Nat,'l Taiwan U. Taipci and BNL) 

Sccoildary Ion Mass Spect,roscopy and Syncl~rotron X-ray Fll~orrscrncc~ in tllc St~ltly Of 

the Variation in Mctal Contcnt with Ti~nc ill Trcc Rings ....................................... 

R. Miirtill, T. K. Sllalll (U. V\Tcstrr~l Ontario: CiI~ladiI). I

Determination of Zinc Content of Poliovirus Protein 2C Expressed in E. coli ................... 

T. Pfister, E. Wimmer (SUNY at Stony Brook), and K. W. Jones (BNL) 

Elemental Microanalysis and Elemental Mapping on Biological Tissues ........................ 

R. Rizzo and F. Vittur (U.Trieste, Italy) 

Reduction Of Soil Mn Oxides During XANES Studies ......................................... 

D.S. Ross, H. C. Hales (U. of Vermont), and G. Shea-McCarthy (U. of Chicago) 

Role of Manganese and Associated Trace Element Chemistry in Plant Diseases ................ 

D. G. Schulze, C. A. Guest, I. A. Thompson, A. Scheinost, and D. M. Huber (Purdue U.) 

Performance of Kirkpatrick-Baez Microfocusing Mirrors on the X26A Microprobe .............. 

S.R. Sutton, M. L. Rivers, P. J. Eng, and G. Shea-McCarthy (U. Chicago) 

Correlated Synchrotron XRF, MicroXANES and Electron Microprobe Analysis on Individual, 

Clmr;ictcriza,tion of Ultra-Light W'cight hlatcrials. Porous hl~ti~ls. Using X-Ray Co~~~piitcd 

Microtomography ....................................................................... 

R.. Scliiiltc, R.. Mcilililas, A. Tobin. ,J. Papazian. T. Donl~~lli~ll (Nortl~rop G~~~~I~III~III). 

B.A. Dowd, D.P. Sidtlons, and B. Andrcn-s (BNL) 

Mcasi~rcincnts of Morpliology and Physical Properties of B1ilhlr in Vcsiculi~tctl Bi~~illt ic 

Rocks using X-Ray Compntcd Rlicrotomography .............................................. 

S.R. Song (National Taiwan U.. Taiwan), 1Y.B. Lindqiiist (SUNY at Stony Brook). 

B.A. Dowd, D.P. Sidtlons. B. Andrcws. and K.UT. .Jones (DNI,) 

X-Ray Coinplitcd Microtomography Stildy on Pilmicc ......................................... 

S.R. Song (National Taiwan U.. Taiwan). W.B. Lil~dqiiist (SUNY i ~t Stony B~ook), 

B.A. Dowd, D.P. Siddons. and K.MT. ,Jones (BNL) 

Bearnline X27C 

Conforma.t,ional Defects in the Crystals of Lon- hIolccular ZYcight Two-Arm Poly(ctliyl(w~ 

Oxide) Fractions Crystallized from tlic hlclt ................................................. 

E. Clica, G. Xuc, B.3. Moon. F.MT. Harris. S.Z. D. Cl~ciig (U. of Akron), B.S. Hsiao 

and F. Ycli (SUNY at St,ony Brook) 

In-sit,ii Crystallizil.tjion Stiidics of Polyblltylenc Terephtl~alatc (PDT) by SAXS/\Z7AXD ......... 

Y. Gao, K.C. Slicth, S. Talil~iiddin. Y. UTa:ang (GE). B.S. Hsiao. F. Yt.11. Z.G. 

Wang (SUNY at Stony Brook) 

SAXS Studies of Dcildriincr Systc111s .......................................................... 

T. J. Prosa, B. J. Bailer, and E. J. Ainis (NET) 

St~ldy of Structure and Morpllology of PVDF Filwrs Undcr Stress Using 

Syl~~h~ot~ol~ R.i~diat,ion ........................................................................ 

J. Wu, J. M. Scliiilt~z (U. Dclawarc), F. Yell. and B. Hsiao (SUNY i~t Sto~~y Brook) 

Bclmvior of Microphase Separation in a Poly(nrct11ai1c-~irca) Film ~i~~tlcr Dcfi)r~natioii .......... 

F. Ycli, B. S. Hsiao, B. Cllii (SUNY at Stony Brook). and B. Saiicr (DIIPOII~) 

Effect of Polyincr Diulcnt on Tlic Lalllclli~r hlorphology of Poly(osyli~ctl~ylclic) Dlo~ltls ......... 

F. Ych, B. S. Hsiao, B. Clm (SUNY at Stony Brook), and B. Saiicr (DiiPont)

Soft X-ray Imaging and C-XANES Linear Dichroism of Nematic 

Phase Transitions in Coal Derived Liquids 


Certain coals, when heated to temperatures > 400°C fluidize. The initially 

isotropic fluids nucleate microscopic, optically anisotropic, spheres which ulti- 

mately coalesce into a highly anistropic fluid. This property has important in- 

dustrial applications in areas of metallurgical cokes and carbon electrode fabrica- 

tion. The chemistry of these fluids is dominated by aromatic molecules. As the 

X-ray beam at X1A is highly polarized, one can use the intensity of the aromatic 

Is-T* transition to follow the generation of anisotropic regions within quenched 

samples of the fluids. This is because the 1s-T* transition is highly polarized per- 

pendicular to the plane of the aromatic ring. Soft X-ray microscopy and micro 

C-XANES spectroscopy has been applied to a series of quenched glasses ranging 

from purely isotropic, to mixed phase, to purely anisotropic. Figure 1 presents 

images of the highly anisotropic quenched fluid (glass at room temperature). Fine 

scale anisotropic domains are clearly evident. It has been recognized that the size 

and topology of the anisotropic domains controls the quality of the material from 

industrial standpoints, however, details on the physics and chemistry that controls 

domain size are minimal. Figure 2 presents C-XANES spectra obtained from a 

single anisotropic domain, but with sample rotation to explore the extent of linear 

dichroism. Although the dichroism is pronounced, the average degree of preferred 

orientation parallel to the electric vector of the X-ray beam is on the order of 23 

degrees. Comparison of the anisotropic spectra obtained at the magic angle with 

spectra obtained from the truly isotropic regions reveals minimal differences in the 

carbon chemistry. This suggests that the isotropic to anisotropic transitions may 

be purely a second order liquid crystalline phase transition. 


X1A 

Carbon and Oxygen XANES and X-ray Imaging of Chemically Differentiated 

Regions in the Cell Wall Structure of Ancient (40-150 Ma) 

Wood * 


X1A 

The fate of biomacromolecular compounds such as lignin and cellulose in ancient 

wood is being studied using the unique capabilities of the STXM at X1A. The 

cell wall of wood is chemically differentiated into several distinct regions, e.g. the 

middle lamellae, the primary cell wall, the S1, S2, and S3 regions of the secondary 

cell wall. Mature cells of fresh wood have lignin predominantly located within the 

middle lamellae and S2 region of the secondary cell wall. Recent studies using 

the STXM have revealed that the chemical differentiation within the cell wall persists 

well beyond the stage where the biomacromolecules lignin and cellulose are 

thermochemically altered into essentially new complex geomacromolecules. Efforts 

are currently focused on characterizing the chemical reactions that transform these 

biomacrmolecules, resolved within the discrete regions of the cell wall. High resolution 

soft X-ray imaging on the carbon (Is) absorption pre-edge, e.g. at 285 eV 

corresponding to aromatic carbon's 1s-pi* transition reveals that cell wall chemical 

differentiation persists even after millions of years of preservation (Figure 1). We 

have observed chemical dif ferentiation in samples as old as 135 million years old. 

Micro C-XANES reveals significant differences across the discrete regions of the 

cell well, including variations in the average degree of aromatic ring hydroxylation, 

variations in lignin and cellulose, and variations in the concentration of oxidized 

organic functional groups not initially present in pristine lignin or cellulose (figure 

, \ 

Figure 1. X-ray image of cross section through cell wall of 40 million year old 

wood. Monochromator fixed at 285 eV; contrast based on concentration of aromatic 

carbon. Corresponding C-XANES spectra of middle lamellae, primary cell wall, S1 

secondary cell wall, and S2 secondary cell wall. 

* Financial support by Exxon Education Foundation is gratefully acknowledged

P3 

CO 

C-XANES Linear Dichroism Studies of Single Crystals of Polycyclic 

Aromatic Hydrocarbons * 

X1A 

G. D. Cody (Carnegie Institution of Washington), H. Ade (North Carolina State 

U.), S. Wirick (SUNY at Stony Brook), and J. Waldbaur (Dartmouth U.) 

The recent upgrade of X1A has opened up new opportunities for solid phase 

characterization of relatively large carbonaceous molecules. In particular we have 

acquired high resolution near edge spectra of pure polycyclic aromatic hyclrocar- 

bons. Single crystals of anthracene (Cl4), phenanthrene (Cl4), pyrene (ClG), cry- 

sene (ClB), perylene (C20), and benzo-g-perylene (C22) have been studied to date. 

In each case pairs of high resolution C-XANES spectra have been obtained with the 

electric vector of the polarized X-ray beam parallel with the principal optical axes of 

the crystals (e.g. Figure 1). Anthracene, phenanthrene, pyrene, crysene, perylene, 

and benzo-g-perylene have manifolds of 7, 7, 8. 9, 10, and 11 7i* states, respectively: 

therefore complex spectra are anticipated. The linear dichroisnl studies clearly al- 

low clistinction of pi vs. sigma type polarization; a trivial point at high energies, 

but a very helpful approach for the low energy (Is-3p/sig*) transitions that occur 

in the n~iclst of the 1s-T* transtions. Extended Huckel molecular orbital calcula- 

tions inclutling the Z+1 (equivalent core virtual orbital model) approximation fo 

the photoexcited molecule were used to facilitatr assignrr~ent of t,hr fine structure 

in the near edge region (e.g. figure 2). In principal. the fine structure (figwcs 1 and 

2) may result from vibrational splitting as is common for simple molccliles. The 

EHhIO Z+l calculations suggest, however, that small shifts in the energy of various 

Is-nm transitions may be due to chemically inequivalent carbons. The results of 

these studies are providing the key to onr ~mdcrstantling of micro- chnractcrization 

studies of thermally mctamorpliosetl coals; materials with chemistry tlorninatctl by 

polycylcic aromatic hvtlrocarbons. 

* Financial Support from the Exxon Education Foundation is gratefully apprcci- 

atetl. 

Figure 2. C-X-AXES spectrum of an- 

Figure 1. C-X-AXES spectra of crysene. 

thracene (above). Simulated spectrum 

of anthracene (below) using EHIIO 

The pair of spectra correspo~ld to crys- methods and the Z+1 (equivalent cores) 

tal orientations orthogonal to each and approximation for the photoexcited caralligned 

along the principal optical axes. bon. 

I X-Ray Radiation Damage of PhIMA, PC, and Nylon 6 1 X ~ 1 A 

T. Coffey and H. Ade (NCSU) 

In order to comprehensively understand damage of polymers in X-ray microscopes, 

we have started to investigate radiation damage in a variety of polymers. 

Using the Stony Brook Scanning Transmission X-ray hlicroscope (STXhI) on beamline 

XlA, ['.*] we have compared the radiation damage of three carbonyl containing 

polymers, poly(methy1 methacrylate) (PhIhIA), polycarbonate (PC), and Nylon 6. 

We want to ascertain whether the critical dose for damage to the carbonyl functionality 

depends on the location (main chain vs. side chain) and on the local electronic 

structure. We use Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectra 

to monitor both the decay of the carbonyl peak and the mass loss. We quantitate 

radiation damage by measuring the "critical dose" for the PC and Nylon ti carbonyl 

peak decay and PhIhIA mass loss. The "critical dose" is the radiation dose at which 

the feature sizc is decreased by l/e of its original sizc. Our critical dose for mass loss 

in PhIhlA is 43 eV/nm", which compares favorably with the previous result of 56 

eV/nrn3 ["I. Previous work separates the mass loss effects and the decay of the carbony1 

peak, measuring the critical tlose of the PXI5IA carbonyl peak as 372 eV/nrn3 

I?']. JVe ~nesst~rctl thc critical closes for the carbonyl peaks in PC and Nylon 6 as 

92 eV/nm3 and 1360 e~/nrn"~ respectively. \Vc believe that the differences in the 

critical doses of the carbonyl fiinctionality can be cxplainetl by the local electroi~ic 

strl~ct~ire. A qualitative relation exists between the critical dose and the ionization 

potential of the core electron of the carbonyl carbon atom. As the ionization potential 

of the citrbor~yl carbon aton1 increases, the critical tlose decreases. In polymers, 

thr ionization potential is a measure of the local electron density which reflccts the 

electronegi~tivity and r~urnber of hetero-atoms as nearest neighbors. The ionization 

potentials of the carbonyl carbon atom are: Nylon 6, 288.01 eV; PlIhIA, 289.03 eV; 

and PC. 290.4 e~[.']. This suggests that the critical tlose for the carhonyl group is 

rclatctl to the electronegativity of the nearest neighbors of the carbon atom in the 

carbonyl group, i.e. more electronegativc neighbors imply a smaller criticitl tlose. 

1 C. .lacobsen et al.. Optics Co7n,m,~~nzcntzons 86 (1991), 351. 

t2 l X. Zhang et al.. Nl~clenr Instrurn,ents and .bleth,ods i7, Ph,ysics Research A 347 

(1994), 4:31. 

3 X. Zhang et al.. J. Vnc. Sci. Technol. B 13(4), 1477. 

I 4 I G. Bearnson and D. Briggs. High Resolution .YPS of Organic Polymers. .Tohn 

\Viley ant1 Sons. Ncw York. 1!)!12. 

Figire 1. The chemical structures of Sy- 

Ion 6. P5IM-A and PC. Figure 2. Summary of results.

A High Rate Gas Proportional Counter For Soft X-Ray Microscopy 

X1A 

M. Feser (SUNY at Stony Brook), G. Smith, B. Yu (BNL), J. Kirz, and C. Jacobsen 


A multichannel, low pressure gas proportional chamber is being developed and 

tested for the scanning transmission x-ray microscope (STXM) at beamline XlA, 

to increase the count rate capability well beyond that of existing single channel 

detectors. 

A schematic layout of the detector with electronics is shown in Fig. 1. The 

focused monochromatic x-ray beam enters the detector through a thin (120 nm) 

SiN window. The eight anode wires are connected in groups (from the front) of 1, 

1, 2 and 4. Because of the exponential decrease in x-ray photon intensity in the 

detector (length 5 cm), comparable count rates can be obtained on all four groups 

when the composition and pressure of the gas are optimized for a specific photon 

energy. Uncommon low Z gas mixtures such as neon with a CO2 quench have been 

tested. Each group of anode wires feeds an electronic channel comprising a high 

bandwith preamplifier and shaping amplifier. 

The detector was studied in the energy range from 270 eV to 800 eV on the 

STXM at X1A. The principle of spreading photons over more than one channel 

has been demonstrated with the counter response to photon intensity being quite 

linear (Fig. 2). Images of a test pattern confirmed the good detector performance 

in connection with the microscope. 

LINEARITY OF THE FIRST CHANNEL 

2000 . . 

Figure 1. Layout of the detector and Figure 2. Linearity test of the first chant? 

t~ electronics. nel 

m 

1 The Spatial Distribution and Bonding - States of Carbon in the 1 , , 1 

AlA 

I ~ ~ ~ 8 4Meteorite 0 0 1 from Mars 

G.J. Flynn (SUNY at Plattsburgh), L.P. Keller (MVA, Inc.), C. Jacobsen and S. 

Wirick (SUNY at Stony Brook) 

McKay et al. [l] reported that carbonate globules from the ALH84001 mete- 

orite contain several indicators suggesting ancient biological activity on Mars. One 

indicator is their detection of polycyclic aromatic hydrocarbons (PAHs) "found in 

the highest concentrations in the regions rich in carbonates," and associated with 

magnetites and sulfides similar in size and shape to those produced by terrestrial 

bacteria [I]. However, the spatial resolution of the PAH measurement (50 microm- 

eters analysis spot) was comparable to the size of individual carbonate globules 

and far larger than the magnetites and sulfides which occur in thin rims on the 

globules. We employed the Scanning Transmission X-ray Microscope (STXM) at 

beamine XlA, using a 50 nanometer analysis beamspot, to determine the spatial 

distribution and the bonding state(s) of carbon in the ALH84001 meteorite with a 

spatial resolution about 1,000 times that achieved by McKay et al. [I]. Ultrami- 

crotome sections of the carbonate and of rim material from the AL84001 meteorite 

were examined. 

The C-0 bond in carbonate gives rise to a strong absorption near 290 eV [2], 

while C-C, C=C, and C-H bonds have strong absorptions in the 284 to 287 eV 

range. Thus, Carbon X-Ray Absorption Near Edge Structure (C-XANES) measure- 

ments provide a sensitive technique to detect and map the distribution of organic 

or graphitic carbon in a matrix of carbonate. 

C-XANES spectra of the ALH84001 carbonate globule samples showed strong 

absorption at 290 eV, characteristic of the C-0 bond in carbonate, and weaker 

absorptions at 284.8 eV, 286.5 eV, and 288.2 eV. The relative intensities of the latter 

three absorption peaks were approximately constant (where they could be detected) 

over the sample, however the ratio of these peaks to the C-0 peak varied with 

position. This indicates the presence of a second carbon-bearing phase, distributed 

inhomogeneously on the scale of the 50 nanometer beamspot, within the carbonate. 

C-XANES spectra of the ALH84001 dark rim samples showed no absorption at 

290 eV, consistent with the absence of carbonate. Some spots on these sections 

showed two absorption peaks at 284.5 eV and 288.2 eV, indicating the presence 

of C-C, C=C, or C-H bonds. The differences in absorption peak energies and the 

absence of the third peak in the rim sample indicate that the dominant carbon- 

bearing phase in the rim is different from that in the carbonate globule. 

These preliminary results demonstrate the close association of carbon-bearing 

phases containing C-C, C=C, and/or C-H bonds with the carbonate globules and 

the rims, confirming, at a much smaller size scale than reported by McKay et al. 

[1], the association of a carbon-bearing phase with the carbonate globules and the 

rims on these globules from ALH84001. To confirm that the carbon-bearing phases 

in the carbonate globule and the rim are different from one another, as indicated 

by these C-XANES analyses, and to determine if these phases are organic, the 

same ultra-microtome sections analyzed by STXM were examined by micro-FTIR 

at beamline U4-IR [see results in 31. 

References: 1) McKay, D. S. et al., Science, 273, 924-927, 1996 2) Flynn, G. J. 

et al., Lunar Planet. Sci. XXVIII, A42, 1997. 3) Flynn, G. J., "Identification 

of Organic Compounds in the ALH84001 Meteorite from Mars", U4IR Activity 

Report, this volume.

Identification of Organic Compounds in the ALH84001 Meteorite 

from Mars 

XlA, 

U4IR 

G. J. Flynn (SUNY at Plattsburgh). L. P. Keller and PVI. A. Miller (MVA Inc.) 

hIcKay et al. [I] suggest the ALH84001 meteorite contains evidence of possible 

ancient biological activity on hlars. One line of evidence is the concentration of 

polycyclic aromatic hydrocarbons (PAHs). frequently produced by the decay of 

living material, occuring in close proximity to magnetite and sulfide similar in size 

and shape to those procluced by terrestrial bacteria [I]. 

We employed the Scanning Transmission X-Ray hIicroscope on beamline X1A to 

determine the bonding state(s) and the spatial distribution of the carbon in ultra- 

microtome thin-sections of carbonates globules and the rims, where the magnetites 

and sulfides were found, on these carbonates from ALH84001 [2]. Both the carbon- 

ate and the rim sections contained carbon-rich regions, but each gave a different 

C-XANES spectrum, suggesting the major carbon-bearing compound was different 

in the rim and the carbonate [2]. \Ve then examined the same samples using a 

Spectra-Tech micro-Fourier Transform Infrared (FTIR) spectrometer, on beamline 

U4IR, to identify the carbon compounds. 

Transnlission Electron hIicroscope (TEhI) examination of the rim samples indi- 

cated were composed of feldspathic glass antl contained micron-size chromite, and 

regions of fine-grained magnetite antl sulfitlc. The FTIR spectra of the rim sam- 

ples showed a broatl absorption near 1000 cm-', characteristic of silicate glass, and 

two weaker features at 2918 cm-' antl 2850 cm-I. These two features are consistent 

in position and relative depths with t,he symmetric and asymnletric strctching 

vibrations of the C-1-12 in aliphatic hytlrocarbons. 

The FTIR spectra of the carbonate globde showed a narrow absorption at about 

1500 crrl', characteristic of carbonate, and a weaker absorption at 2964 cm-'. Two 

even weaker features appear at 2920 cm-' and 2850 cn-'. The feature at 2964 cm-' 

is characteristic of the C-H3 asynlrnetrical stretching vibration. Although a weaker 

C-H3 symmetrical stretching vibration generally occurs near 2870 cm-', this feat~~re 

is absent in the carbonate globule spectrum, and is suppressed in certain compoi~nds 

containing C-H3 groups. One particdarly good spectru~n of the carbonate globnle 

sample appears to show a weak, broatl absorption over the range 2990 cm-I and 

3060 cm-'. Follow-up measurements, to determine if this feat~~re could indicate the 

detect,ion of C-H strctching vibrations of a mixt~~rc of PAHs, which wo~~ltl have an 

absorption near :3030 cnl-', are in progress. 

These preliminary results confirm that high concentrations (of order 1 to 5 percent) 

of organic carbon are associated with the carbonate globules antl rims in 

ALH8-1001, antl further confirm thc STXI observation that the rim antl the carbonate 

globule contain different types of carbon. The latter result seems to rule 

out the simplest form of organic contamination of ALH8-1001. simple evaporation 

of an organic-rich fluid. which would be expected to leave the same residue in both 

the carbonate globules and the adjacent rim material. although selective, nlineral 

specific. contamination cannot be excluded. 

References: 

1) AIcKay. D. S.. et al. Science. 273. 924-927. 1996. 

2) Flynn. G. J. et al.. Meteoritics. 32. -146--147. 1997. 

Carbon Mapping and Carbon-XANES Measurements on Interplane- 

tary Dust Particles 

X1A 

G. J. Flynn (SUNY at Plattsburgh), L. P. Keller (ILIVA Inc.), S. Wirick and C. 

Jacobsen (SUNY at Stony Brook) 

Rlodeling by Anders [I] indicates that interplanetary dust particles (IDPs) may 

have been an important source of organic matter on the early Earth, providing some 

of the pre-biotic organic compounds required for the development of life. The IDPs 

collected from the Earth's stratosphere by NASA are carbon-rich, containing an 

average of 12 weight percent carbon [2]. However, the ratio of elemental to organic 

carbon in the IDPs is not well-established. We have previously demonstrated that 

the Scanning Transmission X-ray hIicroscope (STXhI) on beamline X1,4 can be used 

to map the spatial clistribution of carbon and to determine the carbon bonding states 

by Carbon-X-Ray Absorption Near Edge Structure (C-XANES) measurements [3]. 

The carbon in two of the first three IDPs examined by C-XANES is dominated by 

poorly graphitized or amorphous elemental carbon rather than organic carbon [3]. 

In a continuation of that study, ultramicrotorne thin-sections 100 to 200 nm 

thick) of three additional IDPs, L2011*B5, L2009.74, antl L2009 F2, have been 

examined using the STXhI. L2009.J4 exhibited several distinct nlorphologies of 

carbon-rich material: intliviclual micron sized grains, thin regions partially surronntling 

non-carbonaceous grains (apparently carbon coatings about 100 to 200 

nm thick on those grains), ancl larger regions of carbon-rich material (microns in 

size) containing non-carbonaceous grains. A C-XANES spectrum of an intlivitlual 

micron-sizod carbonaceous grain in L2009.J4 showetl absorption peaks near 285 

cV antl 289 eV. consistent with C-C antl C-0 bor~tls respectively, and inconsistent 

with graphite or arnorphous carbon. L201 l*B5 showetl little absorption below the 

C-edge, indicating that this particle is dominated by carhorlaceous material. C- 

XANES analyses of carborl-rich regions in L2011*B5 are in progress. L2009*F2 

showed no obvious carbo~l-rich areas, indicating the bulk carbon content of this 

IDP is significantly lower than the other two 1DPs in this study antl three IDPs 

prcviousl,v examined [R] in the STXRI. However. C-XANES specta of some spots on 

L2009*F2 showed an absorption peak near 289 eV, an energy inconsistent with the 

absorption spectrum of graphitic or arnorphous carbon. Thus, the C-XANES analyses 

of L2011*B5 and L2009*F2 indicate the presence of carbon in a form other than 

graphite or arnorphous carbon. The absorption near 289 eV in each of these samples 

is indicative of a C-0 bond, suggesting an organic phase. The ultra-microtome section 

of L2009*F2 was subsequently exanlined by micro-Fourier Transform Infrared 

(FTIR) spectroscopy at bearnline U4IR. and the IR signature of the C-H stretching 

vibrations in an aliphatic hydrocarbon was detected, confirming the presence of an 

organic cornpound in that sarnple [see results in 41. 

These results on L2009*F2 demonstrate that STXhI and micro-FTIR can be 

performed on the same ultra-microtome thin section. using the STNI to map the 

distribution of carbon in the section. to determine the bulk carbon content. antl to 

identify the graphitic or amorphous elemental carbon. and using the micro-FTIR 

to determine the types of organic carbon present. 

References: 1) .Anders. E. Sature. 342. 255-257. 1989. 2) Thomas. K. L. et al.. 

Geochim. Cosmochim. =\eta.. .57. 1551-1566. 1993. 3) Bajt. S. et al.. Lunar Planet. 

Sci. XXVII. 57-58. 1996. 4) Flpn, G. J.. et al.. "Identification of Organic Carbon 

in Interplanetary Dust by FTIR." U4IR -Activity Repport. this volume. 

S,

Determination of Partial Miscibility in Phase Separated PBT-PC 

Blends by STXM 1 1 

Y. Gao, T. Banach, V. Watkins, G. Hutchins (GE), D. Pierson, A.P. Smith, H. 

Ade (NCSU) 

In partially miscible, phase-separated polymer blends, the amount of miscibil- 

ity is one of the most important parameters that determine physical and thermal 

properties. In completely amorphous blends, such miscibilities may be obtained ac- 

cording to the Flory-Fox equation by measuring the glass transition temperatures 

of the blend. However, this equation does not pertain to blends of semi-crystalline 

and amorphous materials. Due to solubility differences, it has also not been possi- 

ble to directly measure it from a single domain. Recently, we have used the X1A 

SUNY Stony Brook Scanning Transmission X-ray Microscope (STXM) to investi- 

gate the partial miscibility in a phase-separated polymer blend consisting of 45C K 

edge. This particular specimen has lamellar shaped domains with adequate domain 

size for both PBT and PC rich regions. Since PBT and PC each have their own 

characteristic spectroscopic features in the vicinity of the C K edge, the observed 

spectra can be deconvoluted by using the Target Factor Analysis (TFA) method 

to obtain the percentage of each component given the reference spectra from the 

pure PBT and PC specimens. We have measured three PBT rich and three PC 

rich regions using a focused X-ray beam, and then defocused the beam to obtain 

an average composition from a much larger area. The table below summarizes the 

weight percentages obtained by TFA analysis. 

It appears from the data that PC has a higher degree of miscibility in PBT: 

two out of three PBT rich regions contain more than 113 of PC, while in all the 

three PC rich region, the amount of PBT is about 114. When the defocused X-ray 

beam was used, the measured composition was 48/52, being very close to the actual 

composition. It is necessary to mention that these results are still preliminary and 

the calculated values may contain systematic errors due to the complication from 

a halo around the incident X-ray micro beam, and variation in specimen thickness. 

We estimate that the spectral contamination due to the halo is at least several per 

cent. All these along with the instrumental stability of the XlA-STXM, will be 

improved in the future experiment. 

Figure 1. 

I X-ray Microscopy of Frozen Hydrated Specimen 1 1 

J. Maser, S. Wang, A. Osanna, S. Spector, C. Jacobsen, J. Kirz (SUNY at Stony 

Brook) 

The cry0 Scanning Transmission X-ray Microscope (cryo-STXM) at the XIA 

beamline is capable of imaging frozen hydrated specimens of several micrometer 

thickness at a temperature of 120 K and below [I]. It allows us to image and analyze 

biological objects such as cells at sub-100 nm spatial resolution without the need for 

chemical fixation, staining or sectioning. Spectromicroscopy and microspectroscopy 

can be performed at a spectral resolution of up to XIAX = 4000. The cryo-STXM 

is designed as a vacuum system. This allows us to make use of the full spectral 

range of x-rays provided by the X1A beamline. 

To demonstrate the increased structural stability of radiation sensitive specimens 

at low temperatures, we exposed several areas in the nucleus of a 3T3 fibroblast 

cell to radiation doses in excess of 10' Gy. Fig.1 shows the frozen hydrated speci- 

men after exposure. Even though ionization and damage from secondary electrons 

has presumably caused the breakage of a significant number of chemical bonds in 

the irradiated areas and created radicals, the matrix of frozen water preserves the 

structural integrity of the cold specimen, and no structural damage is manifest. 

Fig.2 shows an image of the nucleus after the specimen was slowly warmed in the 

vacuum chamber to room temperature. Massive mass loss in the areas which have 

sustained large radiation doses leads to the formation of micrometer-sized holes in 

the specimen. Less severe mass loss and other artifacts from freeze-drying can be 

seen in the other areas of the specimen. 

We have recently installed a rotary stage to enable tilting of the specimen around 

an axis orthogonal to the x-ray beam, and started tomographic experiments. We 

have also embarked upon microspectroscopy of frozen hydrated biological specimens. 

All images shown have been taken at a wavelength of 2.4 nm using zone plates with 

an outermost zone width of 60 nm (Rayleigh resolution of 73 nm). 

Figure 1. Image of an unfixed, frozen hy- 

drated 3T3 fibroblast cell at a tempera- 

ture of 114 K. Some spots in the nucleus 

were exposed to a radiation dose in ex- 

cess of 10' Gy. 

Figure 2. Image of the central area of the 

fibroblast from fig.1 after warming the 

specimen. Several holes have formed in 

the areas which were especially heavily 

irradiated before.

I 

W I Lanthanide Polychelate Probes for Scanning X-Ray PIiIicroscopy * I X1A I 

h1.M hIoronne (Lawrence Berkeley National Laboratory) 

To take advantage of this high resolution now available from x-ray microscopes 

for biological studies, we have developed multi-residue polychelate lanthanide compounds 

that are sufficiently bright and radiation stable to be the basis of a family 

of x-ray excitable biological probes. Luminescent lanthanide compounds can have 

very large Stokes shifts (more than 100 nm). As a result? their quantum yields are 

not significantly depressed when assembled into multimeric structures compared 

with single fluor molecules. This makes it practical to increase probe brightness 

by building polychelates capable of binding a large number of lanthanicles(greater 

than 80) in a single probe molecule. However, because of their size and surface 

electrostatic properties, polychelate probes are prone to non-specific background 

staining. In the past year we have been able to overcome initial problem by the 

development of biotinylated lanthanide- polychelates (bioLPC) that are virtually 

free of non-specific labeling artifacts. This approach relies on the tetravalency of 

avitlin/streptaviclin. For example, to label actin stress fibers as in Fig. 1, cells 

are treated with phalloidin-biotin as a primary for filamentous actin, followed by 

streptavitlin, which has four biotin binding site. Only one or two sites is likely to he 

occupied when hound to phalloitlin-biotin leaving two to three available for binding 

to bioLPC. In this way, as many as 240 lanthanide atoms can be attached to a 

single molecular target, greatly increasing probe brightness lmtler x-rays. Using a 

rhotlarnine tracer on the polychelate probe antl fl~~orescencc light microscopy, we 

have tlernonstratetl that bioLPC is capable of labeling with a specificity fully equiv- 

alent to conventional avitlin-biotin probes for act,i11 microfilnmcnts, microtubules, 

riuclear splicing factor, FISH DNA probes, antl other antigens. In April.97, we 

achieved the highest resolution x-ray excited Ilunincscent inlagcs to date using bi- 

oLPC to label actin filaments in 3T3 mouse fibroblasts (Fig.1). \I% believe that 

this data establishes the effectiveness of lanthanide polychrl;ttc probes for scanning 

x-ray microscopy, antl fully expect to achieve a five fold improvement in resolution 

over visible light nlicroscopic methods. 

* Data taken using the XlA STXLI developed by the group of Kirz antl Jacobsen 

with support from the 0ff.of Biological antl Env. Res., USDOE untler contracts 

DE-FG02-89ERG0858, antl the NSF ~~nder grant DBI-960.5045. Probe tlevelopment 

supported untler DOE contract DE-AC03-76SF00098. 

3T3 Cell Actin Labeled with bioLPC-Terbium 

0.4 p m Steps 0.2 prn Steps 0.05 p m Steps 

Figure 1. Lanthanide labeled actin filaments viewed at different 

shows expanded region highlighted by the white square in B. 

resolutions. C 

Soft X-Ray Spectromicroscopy Studies on Aqueous Clay- and Soil 

Suspensions * I X ~ I A 

U. Neuhausler (SUNY Stony Brook, U. Gottingen), C. Jacobsen (SUNY Stony 

Brook), D. Schulze (Purdue U.): D. Stott (USDA), S. Abend (U. Kiel) 

In clay and soil science, structural properties as well as surface reactions and many 

other processes of interest depend on water, solutions or other liquids surrounding 

the actual sample. 

In order to start different studies on these fields, a wet specimen cell matched to 

the special requirements of the X1-A Scanning Transmission X-Ray hIicroscope has 

been designed. A section overview of this wet cell is shown in figure 1. 

The wet cell consists of two 100 nm thick silicon nitride windows that are pulled 

together by surface tension forces and form a suspension/solution layer of a few 

micron thickness, which allows detection of soft x-rays in transmission. 

First results show the capability of the cell to be used to take XANES spectra 

and irnaaes from linuid antl aolleous sam~les with sub 100 nm s~atial resolution 

(~igures-2 and 3). 

* This work was supported by a fellowship for Ph.D.-research studies (UN) from 

German Academic Exchange Service (DAAD) and bv the Office of Biological and 

Environmental Research, U.S. DOE under contract DE-FG02-89ER60858. 

SILICON NITRIDE WINDOWS1 y O-RING 

I=@ 

28.6 Mh4+-l 

SHIM STOCK 0.025 MM THICK 

Figure 1. Section overview of the wet 

specimen chamber. 

Figure 2. C-XANES spectra of paraffin 

oil (bulk sample) and hydrated polyacry- 

lamicle macromolecules. 

Figure 3. A fully hydrated aggregate 

consisting of 2-0.2 jm~ kaolinite clay particles 

antl polyacrylamide (P=\lI). an organic 

flocculant. suspended in an aqueous 

solution of 0.01SI CaC12. (The kaolinite 

is the Clay Minerals Society source 

clay KGa-1. Clay content is 10 mg/mL. 

P-111 content is 0.005 mg/mL.).

I Soft X-ray Spectroscopy of Amino Acids and Peptides * I X ~ ( A 

A. Osanna, C. Jacobsen, and J. Kirz (SUNY at Stony Brook) 

Using the Stony Brook x-ray microscopes, we have continued investigating 

XANES spectra of amino acids and peptides at the carbon edge [I]. In addition, 

we have begun to acquire XANES spectra at the oxygen edge. Carbon edge 

spectroscopy was performed in the ambient environment microscope (STXM); the 

recently commisioned cryogenic x-ray microscope (CryoSTXM), which operates in 

high vacuum [2], allowed us to obtain oxygen edge spectra for the first time. For 

both microscopes, the amino acids were prepared as dry films on SiN windows. 

At the oxygen edge, the amino acid spectra show a strong T* resonance due to 

the C-0 double bond in the carboxyl. The oxygen edge spectrum of Glutamic Acid 

at 0.2 eV resolution is shown in Fig. 1. 

At the carbon edge, we have continued our efforts towards a complete database of 

the 20 amino acids that make up mammalian proteins. In addition, we have started 

investigating collagen that consist only of a small number of different amino acids. 

111 J. Boese et al.. J. El. S~ect. Rel. Phen. 85 (1997) 

121 J. Maser et al., in: x-R~~ Microscopy and ~pkctro~icrosco~~. Springer Series 

in Optical Scienes (1997) 

0.0 3 

520 530 540 550 560 570 

Energy (eV) 

Figure 1. Spectrum of Glutamic Acid at the oxygen edge. The peak at 531 eV is 

due to the C-0 double bond in the carboxyl group. 

4d w * Support from the Department of Energy under contract DE-FG02-89ER60858 

Soft X-ray Spectroscopy of Frozen Hydrated Specimens * 1 XlA 

A. Osanna, C. Jacobsen, J. Kirz, J. Maser and S. Wang (SUNY at Stony Brook), 

R. Balhorn (LLNL) 

We have begun to use the X-1A cryogenic scanning transmission x-ray microscope 

to investigate radiation-sensitive specimens in their natural (wet) environment. [I]. 

We have started imaging human sperm at energies around the oxygen edge to 

extend our abilities to identify defects in sperm chromatin structure that may be 

responsible for certain types of male infertility. XANES imaging at the carbon 

edge has been used to map the DNA and the protein distribution in mammalian 

sperm heads [2]; however, due to the high dry mass of human sperm heads, it has 

not been possible so far to determine the DNA and protein distribution for human 

sperm. DNA is packed inside the nuclei of mammalian sperm by two small proteins, 

protamine 1 and protamine 2. The protamine 2 content of sperm appears to vary 

widely among different species of mammals. An increasing number of studies have 

correlated alterations in the relative proportions of protamine 1 and 2 in the sperm 

of humans with male infertility. [2] 

At the oxygen edge, the increased absorption length of soft x rays compared to 

the carbon edge has allowed us to image these specimens for the first time. The 

specimens were prepared in frozen hydrated form by plunge-freezing a suspension 

of sperm cells on an electron microscope grid. We have begun acquiring protein and 

DNA spectra at the oxygen edge. In addition, in order to determine if a specimen 

is embedded in truly vitrified ice, or if the water crystallized, we have started to 

investigate high-resolution spectra of amorphous and de-vitrified ice. 

[I] J. Maser et al., this volume and in: X-Ray Microscopy and Spectromicroscopy. 

Springer Series in Optical Sciences (1997) 

[2] X. Zhang et al., J. Struct. Biol. 116 (1996) 335-344 

Figure 1. Image of a frozen hydrated human sperm head at 530 eV. 

- 

* Support from the Department of Energy under contract DE-FG02-89ER60858

tj 

W 

h/Iorphology of Rubber Toughened PhIMA Blends with X-ray Mi- 

croscopy * 

A. P. Smith, H. Ade, R. J. Spontak and C. C. Koch (NCSU) 

X1A 

Toughening of plastics by inclusions of small amounts of rubber has long been rec- 

ognized as a method to improve the impact properties of brittle polymers. We have 

begun a study of the rubber toughening of poly(mettryl methacrylate) (PMRIA) with 

ethylene-alt-propylene rubber (EPR) with the non-equilibrium processing route of 

mechanical alloying. Determination of the blend morphology for this system with 

conventional means is prevented due to the absence of a preferential stain. IVe 

have therefore employed the Stony Brook Scanning Transmission X-ray LIicroscope 

(STXhI) and its iriherent sensitivity to chemical functionality to ascertain the blend 

morphology of this system. Three blentls were prepared by milling 25/75 w/w 

EPR/Pi\IhIA polymer mixtures at cryogenic temperatures (-180 "C) for 1, 2. and 

5 hours respectively. The powders were subsequently melt pressed at 200 OC antl 

20 hIPa for five min. and then quenched. The samples were then cryomicrotomed 

to form thin sections. Figure 1 contains x-ray micrographs of the blentls milled for 

a) 5 hrs. b) 2 hrs, and c) 1 hr respectively. These nlicrographs were acquired at a 

photon energy of 287.6 eV where the EPR appears dark. These micrographs show 

that fine-scale dispersion of the EPR within the PAILIA has been achieved with 

EPR domain sizes of 3 pm antl smaller. The rnorphologv observed in the 1 and 2 

hr milling is about the same while the 5 hr rnilling has started to break the larger 

EPR domains into smaller pieces. This tlernorrstrates that with increased milling 

tinre, the EPR domain size will be smaller antl raises the potential of forming sub- 

micron particles with increased milling time. Rlrther work will inclutle cxtcntling 

the rnectmuical alloying time, varying the post alloying processing and correlating 

the ohservctl morphology to the physical properties of each blend. 

h4orphological Characterization of Mechanically Alloyed PETIVectra 

Blends with X-ray Microscopy * 

We have used high-energy ball milling to form non-equilibrium blends of the 

highly immiscible polymers poly(ethy1ene terephthalate) (PET) and Vectra (75125 

mol% oxybenzoate/2,6 oxynaphthoate). Characterization of the blend morphology 

for this system by conventional TEhI is severely hindered by the lack of a preferential 

stain. Therefore, we have employed the sensitivity to chemical functionality 

inherent to the Stony Brook Scanning Transmission X-ray hIicroscope (STXhI) to 

determine the morphology of three separate blends of these polymers. Figure 1 

shows micrographs obtained from a)75/25, b)9O/lO. and c)99/1 w/w PET/Vectra 

mixtures acquired at a photon energy of 286.7 eV mhere the Vectra appears dark. 

These blends were each cryo-milled (-150 "C) for six hours and subsequently melt 

extrlrded at 285 "C. The micrographs in Figure 1 show that the Vectra forms tlispersions 

within a PET matrix ranging in size from 0.1 prn to 20 pm, an indication 

of fine-scale mixing. In addition, the Vectra dispersions possess an internal structure 

which is potentially due to a) thickness variations, b) chemical variations (PET 

within the Vectra dispersions). and c) orientation of the liquid crystalline Vectra. 

Since the STXhI is sensitive to all of thickness, chemistry, antl orientation, it can he 

utilized to tleconvolve these effects. A series of images of the 90/10 blend acqnired 

at different photon energies show that no PET appears to be within the Vectra tlispersions 

while images acquiretl with the electric polarization vector rotated by 90" 

tlenrorrstratc that there is a small orientation component to the internal structllre. 

However, most of the internal structure is due to the thickness variation within the 

sample. These results constitute the first succ~ssfi~l morphological characterization 

of a system containing Vectra. 

Figure 1. X-ray micrographs of 25/75 w/\v EPR/PAIlI=\ blends mechanically al- Figure 1. X-ray ~nicrornraphs of a)75/23. b)90/10. and c)99/1 w/w PET/lrectra 

loyed for a) .5, b) 2. and c) 1 hours respectively acquired at 287.6 el7 where the EPR blends acquired at 28g7 el7 where the Vectra appears dark. The small \Ectra 

appears dark. dispersions indicate fine-scale mixing has been achieved. 

Supported by SSF Young Investigator Award (DlIR-9458060). * Supported by NSF Young Investigator Award (DlIR-9458060). 

X1A 

A. P. Smith, C. Bai, H. Ade, R. J. Spontak, C. hl. Balik, C. C. Koch (NCSU), and 

C. Saw (HCC)

G 

u1 + 

NEXAFS Spectromicroscopy of Dispersed Phases in Polyurethane 

Polymers * 

S.G. Urquhart, H. Ade, A.P. Smith (NCSU), E.G. Rightor (DOW Chemical), and 

A.P. Hitchcock (McMaster) 

We utilize the chemical sensitivity and spatial resolution of the Stoney Brook X1A 

Scanning Transmission X-ray Microscope (STXM) to chemically analyze sub-micron 

phase segregation in polyurethane polymers. An understanding of the connections 

between polymer formulation, the chemical nature of the segregated phases, amd 

the physical properties of the resulting polymer is important in the development of 

improved polyurethane materials. Chemically sensitive x-ray absorption contrast 

mechanisms are used to image polymer phase segregation, and Near Edge X-ray 

Absorption Fine Structure (NEXAFS) spectroscopy are used to chemically charac- 

terize sub-micron regions that are inaccessible by other micro-analytical techniques. 

We have used x-ray spectroscopy and x-ray microscopy in the STXM micro- 

scope to investigate the chemical character of styrene acrylonitrile (SAN) and 

polyurethane (PIPA) precipitates in a polyether-rich polyurethane matrix. In Fig- 

ure 1, the Near Edge X-ray Absorption Spectra (NEXAFS) of SAN and the polymer 

matrix are presented, together with STXM images recorded at specific x-ray ener- 

gies. In image "A" (recorded at 285.1 eV), both SAN and PIPA precipitates are 

observed. This x-ray energy corresponds to C 1s + mc=c electronic transitions in 

phenyl groups, which are in high concentration in the PIPA and SAN precipitates. 

In image "B" (recorded at 287.1 eV), SAN precipitates are exclusively observed. 

This x-ray energy corresponds to an acrylonitrile-specific electronic transition (C 

1s + T*c=N). It is also interesting to observe the presence of a "halo" around the 

SAN precipitates in image "C" (recorded at 289.0 eV), indicating the presence of a 

chemically distinct region at the precipitate-matrix interface. 

Energy ( e ~ ) 2pm I 

Figure 1. (left) Near Edge X-ray Absorption Spectra of styrene acrylonitrile (SAN) 

the polyyurethane matrix. Vertical lines indicate image energies. eV), precipitates 

with high phenyl-group only SAN interface. 

Work supported by NSF Young Investigator Award DMR-9458060 

I Nano-Tomography with X1A Cryo Scanning X-ray Microscope I X1A I 

Y. Wang, C. Jacobsen, A. Kalukin, J. Kirz, J. Maser, A. Osanna (SUNY at Stony 

Brook) 

The Cryo Scanning Transmission X-ray Microscope (cryoSTXM) is entering operation 

at X1A beamline of NSLS[l]. It has produced images of test-pattern and 

frozen hydrated biological samples at lateral spatial resolution of 70 nm and spectral 

resolution of X/AX = 4000 during commissioning experiments. By using a TEMtype 

cry0 specimen holder, an unfixed biological specimen (3T3 fibroblast cells used 

for demonstration) is maintained below -165°C during imaging, so that it is able 

to withstand radiation dosage up to about logGy before structural damage is observable. 

This level of radiation tolerance allows the acquisition of multiple images 

with a single biological object for tomography or XANES imaging[2]. 

The airlock of the cry0 specimen holder is mounted on a rotary stage to allow 

single-axis tilting of the specimen within a f 50° angular range. The figure below 

shows a frozen hydrated 3T3 cell reconstructed from 8 projections in a f 20° angular 

range with algebraic reconstruction technique (ART). Other reconstruction 

and restoration technique are being explored to improve the image quality. This 

technique has also been combined with spectroscopy to study chemical composition 

of a sample in three dimensions. Besides the applications in biology, we have 

performed experiments to study the possibility of examining defects in materials 

typically used in semiconductor industries with cryoSTXM. The figure below shows 

a tear in a copper film. 

1 J. Maser, et. al., this volume 

I 2 I X. Zhang, et. al., Mapping and measuring DNA to protein ratios in mammalian 

sperm head by XANES imaging. Journal of Structural Biology, 116:335-344, 1996. 

Figure 1. Reconstruction of a frozen hy- 

drated 3T3 fibroblast cell from 8 projec- 

tions within f 20" angular range, using 

ART. 

Figure 2. A tear in a 100 nm thick cop- 

per film reconstructed from 5 projections 

in f 20" angular range, using a laminog- 

raphy reconstruction technique.

W 

o Quantitative Compositional Mapping of Dewetting and Spinodally 

I Soft X-Ray Emission and Absorption of A1,Gal-,N 1 X~B 1 

Decomposing Polymer Films * 

D.A. Winesett, H. Ade, A.P. Smith, (NCSU) M.Rafailovich, S. Sokolov, S. Qu 

(SUNY at Stony Brook), D. Slep (Hilord Chemical) 

We are examining the spinodal decomposition and dewetting in thin polymer 

films with Near Edge X-Ray Absorption Fine Structure (NEXAFS) imaging utilizing 

the Stony Brook Scanning Transmission X-ray Microscope (STXM). Our studies 

of model systems will provide insight into many thin film applications such as dielectric 

coatings and colloidal paint systems. The primary advantage of NEXAFS 

imaging is its capability of quantitative compositional analysis. We acquire a series 

of iniages of the same sample area at photon energies that are characteristic of each 

polymer and extract thickness maps of constituent components that are present. 

This allows for the determination of the overall thickness (analogous to topography 

with Atomic Force hlicroscopy) as well as projected thickness mapping of each polymer, 

results not obtainable by AFh1 or other techniques. From th~s, we might be 

able to tletermine the three tlimensional structure of all components in the resulting 

systerns, ancl in turn determine important parameters such as interfacial energies. 

As an illustration of the present work, we show compositional thickness rnaps 

(lighter areas are thicker) obtained from a 1460 nm thick, 50/50 w/w blend of 

polv(rnetliyl methacrylate) (PhIhIA) antl Polystyrene (PS). Fig. 1 antl 2 are for a 

sample annealed for 10 min antl 1 week, respectively. Thickness maps (a), (b), and 

(c) are the PhIhIA, PS and total thickness maps, respectively. Annealing causes 

these two irnrniscible polymers to phase separate. Initially, we observe smaller domains 

of mixed PS antl PllhIA composition, but with time they form larger, separate 

regions of relatively uniform antl pure composition. The images of the sample 

annealed for one week indicate a thin layer of pure PMhIA (Fig. 2a) throughout 

the sample which grows thicker in areas surrounding the smooth spheroids of PS 

(Fig. 2h). This configuration is indicative antl qualitatively consistent with the 

encapsnlation of PS inside a continuum of PLIhIA. Overall thickness rnaps (formed 

by s~~nl~ning the PS antl PRI?rIX rnaps) are consistent with AFL1 data acquired from 

the same samples. \Ve can study the clgnamics of tlecomposition by imaging samples 

annealed for various lengths of timc. I& have used similar procedures to study 

the tlynarnics arid composition profiles of tlewetting hilayers of PS and brorninated 

PS. 

IIork supported by SSF Young Investigator .Award (DlIR-9458060) 

X1A 

L.-C. Duda, C.B. Stagarescu, J. Downes, and K.E. Smith (Boston University) 

We performed soft x-ray emission (SXE) and absorption studies at the N-edges of 

A1,Gal-,N for various concentrations, x, ranging from 0 to 1. Soft x-ray emission 

and absorption spectroscopy provide knowledge about the occupied and unoccupied 

partial density of states, repectively. In the present study we focused on the N 2p 

states which form an important part of the nitride's valence and conduction band. 

The members of the semiconducting nitride alloy family A1,Gal-,N are particu- 

larly interesting to study because they can be epitaxially grown at any concentration 

x which is important for applications such as blue lasers. The energy gap varies 

between about 3.5 eV for GaN and 6.2 eV for AlN. The behaviour of the energy gap 

for the alloys is still a matter of debate in current literature. We introduce SXE 

spectroscopy as a new technique to address this question. Figure la shows how 

the valence bantl (VB) develops as the concentration is varied from x=O to x=l. 

Basically, the bottom of the valence bantl renlains unchanged in energy but the top 

of the valence band becomes increasirrgly narrower for increasing x ancl therefore 

the VB maxirnurn is found at lower energies (see arrows in Fig. la). 

In contrast, we find no change in the oriset of the N K-absorption edge (Fig. lb) 

as the concentration is varied. This surprising result is still under investigation but 

may have its roots in the fact that the core hole in the final state distorts the eriergy 

positions. 

SXE spectroscopy can be used to study hybridization phenomena that are ob- 

scnred in less selective spectroscopies such as VB photoemission. Fig. lc shows (on 

a binding energy scale) that N 2p states in pure GaN extend far below the top of 

the VB antl "resonate" with Ga 3tl states at abol~t 19eV below thr top of the VB 

maximum. For AIN, however, the situation is different because there are no d-states 

at this energy antl thus N 2p-states do not occur at such high birding energies. 

Finally, a comparison of t,hc theoretical partial DOS of pure AlN and experiment 

shows good agreement (Fig. Id). For comparison the SXE spectrum of pure GaN 

is shown (dashed line) illustrating the difference of the gap sizes. 

Figure 1. (a) Top left: (b) top right: (c) bottom left: (d) bottom right.

w 

I Shape Resonances in the Series C2H2, C2H4 and C2Hs * 1 XlB 1 

B. Kempgens, H. M. Koppe, A. Kivimaki, M. Neeb, K. Maier, U. Hergenhahn and 

A. M. Bradshaw (Fritz-Haber-Institut, Berlin) 

Local maxima in the photoabsorption spectra of small molecules just above 

threshold are commonly identified as shape resonances. Their occurrence is ex- 

plained either by an amplification of the photoionization process via a virtual an- 

tibonding orbital, or by scattering of the outgoing photoelectron on the molecular 

core. In the latter picture, the uptake of angular momentum in the scattering 

process creates a potential barrier thus trapping the continuum electron. A semi- 

empirical linear correspondence between bond length and the shape resonance po- 

sition in the respective near-edge absorption spectrum has been proposed ('bond 

lengths with a ruler'). 

We have measured low kinetic energy photoelectron spectra of gaeous C2H2, C2H4 

and C2Hs above the C 1s threshold. By integration of the respective peaks we were 

able to distinguish contributions from the C IS-' single hole state and satellite 

channels in the photoionisation cross section. Satellite lines in photoionization are 

due to a simultaneous valence excitation occuring upon removal of the core electron, 

and are separated from the main line at a lower kinetic energy. Our results show 

that satellite channels play a much stronger role in above-threshold cross-section 

enhancement than contributions from the C IS-' single hole state [I]. In CzH2 and 

CzH4 this enhancement takes place at photon energies formerly identified as shape- 

resonance positions from photoabsorption curves. Our results show that care must 

be taken in the interpretation of photoabsorption measurements, as they provide 

only indirect information on the underlying processes. Further, we call into question 

whether there is a simple correlation between shape resonance position and bond 

length even in polyatomic molecules. 

[l] B. Kempgens, H.M. Koppe, A. Kivimaki, M. Neeb, K. Maier, U. Hergenhahn 

and A.M. Bradshaw, Phys. Rev. Lett. 97 (1997) 35. 

Figure 1. Photoelectron spectrum of 

ethyne showing the C 1s main line and 

various satellite lines. 

* This work has been supported in part 

by the Deutsche Forschungsgemeinschaft 

- Photoabsorption 

0 C 1s-' main line Q 

V 

C 1s-' main line+satellites 

3i0 3i0 3i0 340 340 3id0 


Figure 2. The photoabsorption cross sec- 

tion of ethyne above the C 1s photoion- 

ization threshold. 

I Vibrational excitation in C 1s and 0 1s photoionization of CO * I X1B I 

B. Kempgens, K. Maier, A. Kivimaki, H. M. Koppe, M. Neeb, M. N. Piancastelli, 

U. Hergenhahn and A. M. Bradshaw (Fritz-Haber-Institut, Berlin) 

The high resolution of the X1B beamline has enabled us to measure the vibrational 

fine structure on the C 1s and N 1s level photoelectron lines of several small 

molecules, e.g. [1,2]. Due to a recent change of grating the 0 1s level has now also 

become accessible, e.g. [3]. Here we report new measurements of both the C 1s and 

0 1s main lines in the photoelectron spectrum of CO. From Figure 1 it is clear 

that the vibrational spacing of the 0 IS-' state is significantly lower than in the 

C IS-' state: 226(7) meV compared to 300(4) meV. This can be explained by the 

fact that the 1c (0 1s) orbital of CO has a slight bonding character, whereas the 

2~7 (C 1s) orbital is slightly antibonding. Compared to the ground-state equilibrium 

C-0 distance of 1.128 A, we extract from the analysis of the Franck-Condon factors 

bondlengths of 1.079(2) A and 1.167(4) A for the C 1s and 0 1s core-ionized states, 

respectively. 

[l] H. M. Koppe, A. L. D. Kilcoyne, J. Feldhaus and A. M. Bradshaw, J. Electron 

Spectrosc. Relat. Phen. 75, 97 (1995). 

[2] B. Kempgens, A. Kivimaki, M. Neeb, H. M. Koppe, A. M. Bradshaw and 

J. Feldhaus, J. Phys B: At. Mol. Opt. Phys. 29, 6389 (1996). 

[3] A. Kivimaki, B. Kempgens, K. Maier, H. M. Koppe, M. N. Piancastelli, 

M. Neeb and A. M. Bradshaw, Phys. Rev. Lett. 79, 998 (1997). 

41.0 41.5 42.0 4 


I 

38.5 39.0 39.5 40.0 


Figure 1. Photoelectron spectra showing the vibrationally resolved CO C Is (left) 

and CO 0 1s (right) main lines. 

* This work has been supported in part by the Deutsche Forschungsgemeinschaft

W 

co 

Energy Dependence of the nilultiplet Intensity Ratio in K-level Pho- 

toionization of 02 * 

X1B 

K.R/Iaier, U.Hergenhahn, B. Kempgens, A.Riidel, A.i'vI.Bradshaw (Fritz-Haber- 

Institut? Berlin), and A.Kivimaki (U. of Oulu) 

Compared with the wealth of information on core-level photoionization of closedshell 

molecules, our knowledge of open-shell molecules is much less profound. As a 

general feature, the Is photoelectron spectra of these molecules will show two main 

lines split by the exchange interaction. Naively, one would expect their branching 

ratio to be determined by the spin multiplicity. Investigations with an X-ray line 

source, however, have not shown this expected behaviour in the high energy limit 

rr i 

ill. 

On X1B we have, therefore, investigated the energy dependence of the K-shell 

ionization of 02. This molecule is paramagnetic due to its 3 ~ ground , state; on 

removal of a core electron 0 (IS-') 'C and "C ionic states can be created (Fig. 1). 

The two lines are separated by 1.11 eV. The "c/~c intensity branching ratio would 

be expected to be two from the ratio of the multiplicities, but Fig. 2 shows that 

it increases from a rninirnum at 552 eV steadily towards an asymptotic value of 

2.48 at a photon energy of 750 eV which is in good agreement with the value of 

2.47 found by Bagus et a1 [I]. Theoretical investigations of this branching ratio [I] 

attribute the deviations from two to spin-dependent population differences in the 

valence shell of the ion. Even for the asymptotic value, however, no quantitative 

agreement was reached. 

[I] P.S. Bagus, hI. Schrenk, D.W. Davis and D.A. Shirley, Phys. Rev. A 9 (1974) 

1000. 

').(I '1.5 10.0 10.5 11.0 11.5 12.0 

Kinetic enerq (eV) 

O,O~S "-/?c- - 

0 

8 €3. 

0 k0 51: KU [I 1 

- 1.8 

550 6Nl 650 7(XI 750 liiK) 


I Adsorption and Reaction of NO on Pt / CeOz(001) at Low Temper- I XlB l 

I atures * 

D. R. Mullins, D. R. Huntley and S. H. Overbury (ORNL) 

Highly crystalline 50 - 100 nm films of Ce02(001) were prepared ex situ by vapor 

deposition on a rolled Ni foil. This method produced films with small grains having 

an (001) polar orientation but which were azimuthally disordered. The combination 

of a thin film thickness and a conductive substrate resulted in oxide samples that 

showed no evidence of sample charging even when cooled to 100 K. This enabled 

us to study the adsorption and reaction of NO on CeOz at 100 K by XPS and 

XAS. Previous studies were limited to room temperature and above due to sample 

charging. The current results also enabled us to assign the binding energies more 

accurately. 

Fig. 1 shows the N 1s spectra from NO adsorbed on sputtered Ce02(001) at 100 

K and 300 K. Six different N Is signal can be identified. In the 100 K spectrum, 

the two highest binding energy peaks arc associated with NzO. The highest binding 

energy peak is assigned to the central N atom and the peak at 404.5 eV is assig~etl 

to the ternlinal N. The presence of N20 was also ir~tlicated by the N k-edge XAS 

spectra. The large peak 402.5 cV is assigned to NO. When NO is adsorbed at 300 

K, three additional peaks are observed and the NzO peaks disappear. The lowest 

binding energy peak at 396 eV is assigned to a nitride, Np, species, while the two 

other peaks are assigned to atomic N in different states. Only the atomic N peaks 

persist when the sample is annealed to 900 K. 

The adsorption of NO on Pt / Ce02(001) is similar to what was observed 011 

Rh / Ce02(001). Deposition of Pt onto a sputtered CeO2 sl~rface increases the 

degree of dissociation in subsequently adsorbed NO. \\'hen the NO is tlosetl at 100 

K, none of the NO clissociates over Pt on a fully oxitlizd CeOz surface and only 

partial dissociation occurs upon warming to 300 K. On a sputtered CCO~ surface, 

Pt promotes partial tlissociatiou of NO at 100 K and almost total dissociation after 

warming to 300 K. 

2.6 ,m ;-. -- . - . 

---- .-1 

O m ? 

I 

A ONN 

.2.4 5 5 "I ,' \ ' \ I 

Y ' 

1. d -. ; % _ , \ .,aspma, 

- .2.2 rg 

S 

2 

g =, 8iNO'SwnBredCBO. i--""'_ 

# - 

- @ \lit\ XI8 

\IltcOI?O - 2.0 5' 

~ C O U Z > , ~ , ' ~ ~ 

1.0 M 4m 395 

Bmdlng EneW (evl 

Figure 1. Core-level photoelectron spec- 

Figure 1. N Is ?IPS spectra for NO adsorbed on spnttered Ce02(001) at A) 100 K 

and B) 300K. 

trum of 02. Figure 2. Photon energy dependence of 

the branching ratio into the -'c and 'C Research sponsored by U. S. Department of Energy. Division of Chemical Sciences. 

* This work has been supported in part 

by the Deutsche Forschungsgemeinschaft 

0; ionic states. Office of Basic Ener,q\ Sciences. under contract number DE-r\C05-960R22-164 with Oak 

Ridge National Laboratory. managed by Lockheed IIartin Ener,q\ Research Corp.

I Oxidation of and NO Reactions on Ce Metal Foil * 1 X~B 1 

D. R. Mullins, D. R. Huntley and S. H. Overbury (ORNL) 

The oxidation of polycrystalline Ce metal was studied using 0 Is, Ce 4d and 

valence band photoemission and by 0 k-edge XAS. Previous studies using single 

crystal CeOz films demonstrated that the CeOz was very resistant to chemical 

reduction by either Hz or CO in vacuum and could only be reduced by Ar ion 

sputtering. The aim of the current study was to start with the most reduced form 

of Ce and then increase the degree of oxidation by exposure to oxygen and then to 

compare the behavior of the oxidized surface to single crystal CeOz. 

Exposure of Ce metal to 10 - 20 L of 0 2 at 300 K was sufficient to oxidize 

surface Ce from CeO to Ce+3. Exposure to additional oxygen, > 1000 L, resulted in 

further oxidation from ~ e to + ~ e ~ + This ~ . surface oxide was not thermally stable. 

Annealing the sample to 600 K resulted in the reduction of the surface Ce back to 

Ce+3. This is the exact opposite of the behavior of sputtered CeOz. As shown in 

the figure, sputtered CeOz reoxidizes upon annealing. The behavior of Ce metal 

and CeO2 suggests that the oxygen is very mobile and diffuses from regions of high 

oxygen concentration, i.e. the bulk in CeO2 and the surface on oxidized Ce foil, to 

regions of low oxygen concentration. 

The adsorption and reaction of NO on oxidized Ce metal was similar to the 

behavior observed for NO on single crystal CeOz. If the Ce was highly oxidized 

to predominantly Ce+4, NO uptake was inhibited and only a small amount of N 

containing species was observed on the surface by N Is XPS. Conversely, if the 

surface Ce was predominantly ~ e + considerable ~ , NO uptake was observed and 

nearly all of the NO was dissociated. When Rh was deposited on the Ce+4 oxide 

surface, N uptake was observed with some of the NO adsorbing associatively and 

some dissociating. Addition of Rh to the Ce+3 oxide surface promoted additional 

dissociation of adsorbed NO at 300 K . Heating of Rh deposited on an oxidized Ce 

foil resulted in the encapsulation of the Rh. Rh deposited on a single crystal CeOz 

film is comparatively stable upon annealing. 

Figure 1. Percent ~ e vs + Temperature ~ for sputtered CeOz and oxidized Ce foil. 

The balance is Ce+4. 

* Research sponsored by U. S. Department of Energy, Division of Chemical Sciences, 

Office of Basic Energy Sciences, under contract number DEAC05-960R22464 with Oak 

a Ridge National Laboratory, managed by Lockheed Martin Energy Research Corp. 

I Non-linear Dispersion in Resonant Auger Decay of Water * 1 X~B 1 

M.N.Piancastelli, B.Kempgens, K.Maier, U.Hergenhahn, A.Riide1, A.M.Bradshaw 

(Fritz-Haber-Institut, Berlin), and A.Kivimaki (U. of Oulu) 

The dispersion of a photoelectron line (kinetic energy vs. photon energy) should 

as a result of energy conservation be a linear relationship with unit slope. For 

a molecular photoelectron line containing an unresolved vibrational envelope, this 

statement usually remains valid for the center of gravity. Recently, however, devi- 

ations from linear behaviour for the center of gravity-dispersion in resonant X-ray 

scattering and resonant Auger-decay have been predicted. This means that when 

the photon energy is tuned over a core-to-bound resonance, there is not necessarily 

a one-to-one correspondence between the changes in photon energy and in kinetic 

energy of the center of gravity of some resonantly enhanced photoelectron lines. 

This can be understood in terms of changes in the vibrational population of the 

intermediate and final states when different portions of the resonance are excited. 

Dispersion with a slope larger or smaller than one (the gain in kinetic energy is 

larger or smaller, respectively, than the gain in photon energy) is possible. 

We have measured the resonant Auger decay spectrum of the water molecule at 

the oxygen K-edge. The first two core-to-bound resonances are usually assigned to 

0 1s-4al and 0 1s-2bz excitations. In the absorption spectrum both resonances are 

broadened either by an unresolved vibrational fine-structure or by fast dissociation 

and have widths of about 1.2 eV. The participator decay spectra excited by a 

photon band much smaller than this resonant linewidth were recorded at different 

positions along the resonances. (Participator processes involve the electron that 

has been excited and result in final states with a single hole in the valence shell. 

The same states are usually populated by direct valence photoionization.) We have 

determined dispersion relationships for decay into the 3ay1 and 1bg1 final states 

which demonstrate strong deviations from linear behaviour (Fig. 1). This effect can 

lead to new insights into the shape of highly excited and ionic molecular potential 

curves. 


Figure 1. Dispersion curves (center of peak vs. photon energy) for two Hz0 partic- 

ipator lines. The straight lines correspond to linear dispersion with unit slope. 

* This work has been supported in part by the Deutsche Forschungsgemeinschaft.

7' 

I& 

3 

Negative Thermal Expansion of Cu(001) 

A. P. Baddorf (ORNL) 

State of the art theories, both ab-initio and semi-empirical treatments, are still 

based on ground state interactions. and do not account for enhanced thermal expansion 

observed at the surface of a number of metals. Narasimhan and Scheffler 

have proposed a quasiharmonic model in which entropy contributions to the free 

energy clue to in-plane vibrations lead to large expansions without anharmonicity.[l] 

A superb test of this quasi-harmonic rnodel can be found in the Cu(001) 

system, where ion scattering experiments have shown the in-plane vibrational amplitude 

exceeds the out-of-plane amplitudes, which is rather unusual.[2] We have 

used XRD to determine the structure of Cu(001) between 300 and 1000 K. At 300 

K the results indicate a small contraction in the outermost layer of 1.5% of the bulk 

spacing. This value is corlsistent with other surface studies and can be explained 

by a rearrangement of surface electrons to reduce kinetic energy (Smolo~~chowski 

smoothing). As the temperature is increased, the in-plane vibrational amplitudes 

do dominate. At the same time the outermost interlayer spacing decreases further, 

reaching a minimum near 800 K (Fig. 1). This thermal contraction is opposite 

all expectations: current first principles and semi-empirical theories predict an expansion.[l] 

The quasihar~nonic theory exasperates the issue arid can only increase 

the prdicted expansion. An additional mcchanism, with an inwardly directed force 

is missing from these theories. One possiblity would be a tlynarnical application 

of Smolouchowski smoothing, where the increased surface corrugation intlucetl by 

excitation of in-plane phonon modes lcads to an increased inward relaxation. 

S. Narasinlhan antl hI. Scheffler, to be publishetl. 

Q. T. .Jiang, P. Fentcr, arid T. Gustafsson, Pt~ys. Rev. B 44, 5773 (1991). 

300 400 500 600 700 800 900 1000 

Temoerature 

'2 

Figure 1. Interlayer spacings at the u(001) surface between 300 and 1000 K. 

Between 300 and 800 I( the outermost layer contracts. a result in and semi-empirical 

theories. 

X2A The Periodic Lattice Distortion Accompanying the (3x3) Charge Den- 

sity Wave Phase of SnjGe(ll1) 

X2A 

A. P. Baddorf, V. Jahns. Jiandi Zhang (ORNL), J. hI. Carpinelli, and E. W. 

Plummer (ORNLIUT) 

Recently we have documented the first clear example of a surface charge density 

wave (CDW) independent of bulk phenomena. [l.2] Our experimental and theoretical 

studies of the Ge(111)-(3x3)R30"-M interface, where hI is either Pb or Sn. reveal 

that upon cooling below 255 K (Pb) or 215 K (Sn), the surface reversibly undergoes a 

symmetry reduction to a (3x3) periodicity. The origin of the CD\V in both systems 

is at present unknown. The structure associated with the PLD provides crucial 

information for any physical explanation, yet the SThI images have shed no light 

on the nature of the PLD. At NSLS we have utilized XRD to aclclress the issue of 

the magnitude and character of the lattice distortion that accompanies the CDW. 

The data indicates that the PLD is confined almost entirely to the Sn and first Ge 

layer, i.e. no deep reconstruction. Surprisingly (based on SThI images) there is 

little distortion of the Sn atoms induced by the CD\V, but three of the nine Ge 

atoms in the surface plane in the new (3x3) unit cell move laterally 0.22 Afurther 

towards the Sn atom that according to SThI has an excess of filled states. This 

result suggests a stronger coupling than indicated by Stumpf's calculations [I], antl 

indicates the origin of the CD\V is related to the chemical bond. Specifically, three 

Ge in the outer~nost layer give up their nearly ideal sp:' hybridization, optimized 

for bonding to the GP substrate, to better bond to the Sn. 

[I] J. hI. Carpin~lli, H. H. Wcitering, E. I\'. Plummer, and R. Stnmpf, Nature 

381, 398 (1996). 121 J. hI. Carpinelli, H. 8. Weitering, hI. Bartkowiak, It. Stumpf, 

antl E. \V. Plllmmer, accepted in Phys. Rev. Lett. 

Figure 1. Diffraction from the (3x3) CDLY structure with two structural models. 

The dashed line includes only vertical distortions of Sn antl first layer Ge. while the 

solid line includes lateral displacements of the first layer Ge. -4 perspective view of 

the best fit (3x3) structural model is shown in the insert. with arrows indicating 

displacements relative to the room temperature structure.

td 

5 

In-situ Observation of the Split Diffuse Intensity Maxima of a 

CUO.~P~~.~ Single Crystal 

X2A 

H. Reichert, H. Dosch (U. of Wuppertal, Germany), H.H. Hung, K.S. Liang (SRRC, 

Taiwan), V. Jahns, and D. Zehner (ORNL) 

We have performed measurements of the diffuse x-ray scattering in the disordered 

phase of a Cu-29.8 at% Pd single crystal exposing a (001) surface. Below the phase 

transition temperature the crystal exhibits a long-period superstructure producing 

sattelites along the h,k, and 1 directions through Ll2 superstructure reflections. 

Crossing the phase transition temperature a subset of the sattelite reflections trans- 

forms into diffuse intensity maxima around the positions of Ll2 superstructure 

reflections. Thus, the diffuse maxima exhibit the expected fourfold splitting in the 

disordered phase, associated with Fermi-surface induced effects. Fig.1 shows the 

diffuse scattering in the (l+h,O,l+l)-plane together with a textured powder ring 

from the sample holder. 

In this study the total diffuse scattering has been measured in-situ for a set 

of temperatures along the h and 1 direction through the (101) position. Fitting 

the intensity distibution we have determined the temperature dependence of the 

position of the split diffuse maxima. Fig.2 shows the temperature dependence of the 

distance between two opposite maxima. Both, the positions of the diffuse maxima 

and the related temperature dependence differ from predictions of a recent, state 

of the art first-principles alloy calculation for CuaPd. 

-,~ . H [;.l.u.] 

Figure 2. Temperature dependence of 

Figure 1. Total diffuse scattering in the the separation distance along the line 

(l+h,O,l+l)-plane at T=T0+5K. (h01). 

Modeling of Sandstone Permeability from Medial Axis Analysis of 3D 

Microtomography Images 1 x2B I 

D. Coker, W.B Lindquist, W. Zhu,T-F Wong (SUNY), J.H. Dunsmuir(Exxon) 

We investigate the scientific usefulness of the medial axis transform (MAT) in 

characterizing the geometry of the void and grain phases of rock and in predicting 

bulk flow properties. The MAT is functionally described as the central spine of 

pixels that remain after a binary object is "burned" inward from the exterior. The 

pixel value at the spine is the distance to the nearest interface. The MAT preserves 

the topological and most of the metric information in the image while reducing 

its dimensionality. The motivation for this work is the accurate description of the 

network structure of real rock specimens for use in the modeling of fluid transport 

properties. 

We obtained 1024x1024~512 3D microtomographic images at 5pm resolution of 

six Fontainebleau sandstones with a porosities ranging from 7.5 to 22% and measured 

permeability. Specimens of Berea sandstone and Danish chalk were also 

included in the study .Work is ongoing in segmenting the 3D images into pore and 

grain binary images and computing the MAT.

Computation of Single and klultiple Fluid NMR Relaxation Spectra 

from Differential Absorption Contrast Microtomography Images 

J.H. Dunsmuir and M. Zhou (Exxon Research and Engineering) 

X2B 

In the petroleum industry an important aspect of modeling fluids in small pores 

is understanding the signals that arise from instruments that are placed in a drilled 

borehole to detect hydrocarbons and estimate their producibility. In principle, 

nuclear magnetic resonance (NRIR) tools yield information about fluid saturations, 

probe local properties of pore fluid geometry and have been used to estimate the 

pore size distribution of water saturated reservoir rocks near the borehole wall. 

We have used differential absorption contrast microtomography across the iodine 

K edge to locally reconstruct in saturated sandstones both the pore geometry and 

the distribution of two immiscible fluids and apply a simple method for computing 

the NhIR Ta relaxation spectrum directly fro~n the CT data. Figure 1 shows a 

24 micron resolution slice of a large-pore, high porosity sandstone(porosity = 27'36, 

absolute permeability 4.0 Darcy) containing both oil and brine. In this specimen the 

brine has been labeled with a 5wt% NaI saline solution and the brine distribution 

is mapped by edge crossing. The spccimcn has both oil antl brine wet pore surfaces 

and we infer microporous mineral regions by observing regions where segmented 

iodine antl rock overlap. 

When diffusion is fast enough to maintain spatial uniformity of the magnetization 

across a pore, a linear relationship exists between the ~nagnetization relaxation antl 

the surface to volume ratio of the pore space given by 1/ T2 = 1/ T2h + p S/V 

where Tz is the observed decay time, Tz~ is the bulk decay time of fluid, p (pm/sec) 

is the snrface relaxivity and S/V is the surface to volume ratio of the pore network. 

In this work we use a local measurement of thc snrface to vol~lnle ratio aro~lnd a 

number of randomly selected points in the to~nographically measwed pore space 

to compute the relmation Ta at each point. 'I~c local measure is taken within a 

sub-volume of size L:' selected to lie within the fast diffusion limit L

I Single Crystal Analysis of a New High Pressure Fe-bearing Silicate I X3A1 I 

T. Gasparik, C.L. Cahill, J.B. Parise, (CHiPR, SUNY at Stony Brook) 

The synthesis and stability of NazMgzSiz07 (NMS) at high pressures were first 

reported by Gasparik and Litvin (Eur. J. Mineral. 9, 311, 1997). A crystal chemical 

investigation of the effects of iron on the properties NMS has been undertaken. 

Single crystals of Fe-bearing NMS were synthesized at 1550C and 13.5 GPa in a 

split-sphere anvil apparatus (USSA-2000) from a mix of 1 mol NazSiz05, 5 mol 

MgO, 4 mol SiOz and 1 mol Fe. Two crystals were screened for data collection at 

the X3A1 beamline an imaging plate detection system. The first, approximately 100 

microns in length, produced split diffraction spots and was subsequently dicounted 

as being twinned. A second crystal, approximately 30 microns in length, displayed 

no twinning and was retained for data collection. Preliminary data collection on 

the larger crystal indicated a hexagonal unit cell: a=4.97, c=6.48 . Data collection 

and further analysis of the smaller crystal revealed the presence of a supercell of 

dimensions: a=9.945, c=12.965 . Structure solution and refinement are in progress. 

I The Electron Density Distribution of Mo03(dipic)(HMPA) at 28 K I X3A1 I 

B.B. Iversen, F. K. Larsen, G. H. K. Madsen, C. Wilson, E. Moeller (U. of Aarhus), 

D. Young, and A. J. Schultz (Argonne National Laboratory - IPNS) 

The field of catalytic oxidation chemistry is of interest both in basic science and 

from a technilogical point of view. A large number of studies have been devo- 

ted to unravelling the mechanisms of various key reactions [I]. In the process 

of developing fast experimental techniques to determine accurate electron density 

distributions (EDDs) at very low temperatures using high energy synchrotron radia- 

tion, we decided to study catalytic oxidation from a new point of view, namely 

through analysis of the EDDs of key molybdenum catalysts. We have measured 

extensive 28(1) K Bragg diffraction IP data on MoO3(dipic)(HMPA) , 1, and 

on Mo05(H20)(HMPA), 2. Even though the complexes are structurally similar 

their catalytic behaviour is very different. Unfortunately 2 behaves poorly upon 

cooling to the low temperatures necessary for obtaining accurate diffraction data 

and at present we have not been able to extract structure factors of sufficient quality 

for EDD analysis. We can therefore only report results for complex 1, see figure 1. 

To support the analysis of the X-ray data, time-of-flight neutron diffraction data 

were collected on 1 at the Intense Pulsed neutron Source at matching tempera- 

tures (28K). In Figure 2 experimental details of the synchrotron measurements are 

shown. To model the electron density full multipole expansions were used to fourth 

order on Mo and P, to third order on 0 and N, and to second order on H. Hydrogen 

positional and thermal parameters were fixed at values obtained from the neutron 

data. In Figure 2 preliminary refinement residuals are given. 

Figure 1. ORTEP drawing of the 

molecule showing 90% ellipsoids. 

T*,. 1. crystal daln nnd.rp.rimrimW 

rhdy of MoO3(HMPAl(dim 

for tbe wehrolmn x-ray dillradio" 

~mmpsm- I K 28(11 

Crystalmorphal~gy XIW)0.075 mm. f(010) 00675 mm, XIOI) 0125 mm 

plmm-1 0.92 

unil cell a= 12.191(3]A.b= 18.84(11~,c=7966(21~11A, 

j3 = 90.79O (2) 

wavcknghlA 0.394 

Tmrmrston(rmdmru) 0.93-0.95 

IktecLor dnln 

%an mcthd 

Smdardr 

NO, renccmns measured 

(excluding standards1 

mllmllcction~nr 

h. k. I mgc 

20= OS: 8'awill~ions, 2'ovcrlap (0-1823 

20 = lo0: 4°0edlstionr, lo overlap (180-361'1 

20 = 250: s'oxdlarionr, I* overlap (0-185~1 

0.13 - 1.47 

3 days 

-28.35 -50.50 -11.10 

61778 

OOM(56588 ref# 10811 mcanrl 

3. mured every half haur 

214 

I day 

0.7 -2.11 -0.6 

Figure 2. Experimental details and pre- 

liminary refinement residuals

P 

r~ Single Crystal X-Ray Analysis of a Novel Perovskite CaMnTiaOs X3A1 

J.-H. Park, C. L. Cahill, and J.B. Parise (CHiPR and SUNY at Stony Brook) 

In the investigation of the CaTiO3-hhTiO3 system, a new Cah~InTizOs perovskite 

compound isomorphous to CaFeTizOs was synthesized using a stoichiometric 

mixture of the CaTi03-perovskite and hInTi03-pyrophanite phase(JCPDS29- 

902). Polycrystalline and single crystal (lOx10x20pm) CaSInTizO6 perovskite compound 

was prepared via high pressure-high temperature experiments under 14.5-15 

GPa ancl 1200°C. Synchrotron X-ray diffraction data of a single crystal were collected 

using the imaging plate system at the X3A beamline. A super-cell of dimensions 

a, b=7.5339(5) and c=7.6027(6) A was found. The resulting data is being 

analyzed in cor~~junction with previously collected powder diffraction data. 

(1) K.Leinenweber et al, J. Solid State Chem., 114, 277 (1994). 

Figure 1. X view of CalInTi206. Ti06 and Ca/lIn are represented by octahedra 

and small/large circles. 

The importance of correcting reflection intensities recorded on imag- 

ing plates for incomplete absorption in the phosphor layer * 

J. Zaleski, G. Wu, L. Ribaud and P. Coppens (SUNYQBuff) 

X3A1 

When an X-ray beam is incompletely absorbed in the phosphor layer of an imaging 

plate (IP), a correction for oblique incidence of the beam on the plate becomes 

essential. Relative to the reflections recorded at normal incidence, it is equal to 

K = (1-exp(-pd/coscu))/(l-exp(-pd)) = (1-exp(lnTl)/cosa))/(l-TI) (1) 

with I,,,, = Iob,/K, ancl TI equal to the transmission of the phosphor layer at 

the normal incidence. For short wavelengths (

Synchrotron Small-angle X-ray Scattering Studies on Crystallization 

and Structure of Associated Polymer Blends 

Isothermal crystallization of associated polymer blends, consisting of one-endaminated 

polystyrene (APS, M,=5.6x103) and one-end-sulfonated poly(ethy1ene 

glycol) (SPEG, M,=5.7x103), has been investigated by means of time-resolved 

synchrotron small-angle x-ray scattering (SAXS). 

When APS/SPEG blend weight fraction of 50150 percent) prepared by using 

the freeze-dry method (APSISPEG-FD) was quenched from a temperature higher 

than the melting point of SPEG to the crystallization temperature, the SAXS peak 

intensity (I,,,) increased with time after quenching, while the peak position (q*) 

remained at a constant value as shown in Figure 1. The time dependence of I, 

and q* can be explained by the crystallization of SPEG chains in the confined 

microphase-separated lamellar domain between the glassy PS layer, which is due to 

the formation of a diblock-copolymer-like structure based on the strong association 

between the terminal amino group of APS and the terminal sulfonic acid group of 

-- SPRC - -. 

X3A2 

K. Inomata, L.-Z. Liu, B. Chu (SUNY at Stony Brook), and T. Nose (Tokyo 

Institute of Technology) 

On the other hand, the sample prepared by using the solvent-cast method 

(APS/SPEG-SC) showed a unique time dependence of I, and q* as shown in 

Figure 2, i.e., I, increased with time and revealed a maximum before reaching 

a constant value, and q* decreased rapidly at the beginning of the crystallization 

l Drocess. Such a change of SAXS profile with time can be explained bv assuming 

a macrophase separat?on of an A~S-rich phase and a SPEG-rich phase; and a fog 

mation of dispersed APS microdomains in the SPEG-rich phase. Crystallization of 

SPEG chains would occur in the matrix phase in the SPEG-rich phase. 

P 

& 

0 u 0.3 

0 5000 10000 15000 20000 

time 1 second 

Figure 1. Time dependence of the peak 

intensity (I,,, , filled circles) and the 

peak position (q*, open circles) obtained 

from the Lorentz-corrected SAXS pro- 

files of freeze-dry APS/SPEG-FD after 

quenching from 80°C to 29°C. 

.. , . . , . , . , , . I . . . . 

0 500 1000 1500 2000 

time I second 

Figure 2. Time dependence of the peak 

intensity (I,,,, filled circles) and the 

peak position (q*, open circles) obtained 

from the Lorentz-corrected SAXS pro- 

files of solvent-cast APS/SPEG-SC after 

quenching from 70°C to 30°C. 

Crystalline Structure and Morphology of Microphases in Compatible 

Mixtures of Tetrahydrofuran-Methyl Methacrylate Diblock Copoly- 

mer and Polytetrahydrofuran 

L.-Z. Liu and B. Chu (SUNY at Stony Brook) 

Figure 1. SAXS profiles of the blends 

inthe amorphoui state. The blends 

2TMlT2. 2TMlT3 and 2TMIT4 contain 

20, 30, and 40 wt % of PTHF homopolymer,respectively. 

X3A2 

The crystalline structure and morphology of compatible mixtures of 

tetrahydrofuran-methyl methacrylate diblock copolymers (PTHF-b-PMMA) with 

a tetrahydrofuran homopolymer (PTHF) were studied with synchrotron X-rays. 

Wide angle diffraction was used to study the crystalline structures in a confined 

lamellar region with a thickness ranging from 12.2 to 19.5 nm, and in a PTHF 

matrix with an interface distance between the PMMA cylinders ranging from17 to 

22 nm. As the thickness of the PTHF lamella and the interface are comparable 

with the long period of PTHF homopolymer ca 17 nm under the crystallization 

condition used, the crystalline structure has been found to be very sensitive to the 

average thickness of the PTHF phase. In the case of hexagonally packed cylindrical 

PMMA microdomains, evidenced by the scattering features shown in Figure 1, the 

effects of PMMA cylinders on the crystallization morphology in the PTHF matrix, 

and the effects of the PTHF crystallization on the hexagonally packed structure of 

PMMA cylinders were also studied. It is shown that only when the interdistance of 

two neighboring PMMA cylinders is close or larger than the long period of the pure 

PTHF homopolymer, ordered PTHF stacks can be formed in the PTHF matrix as 

shown by a scattering peak at q = 0.4 nm-1 in Figure 2. 

100 A amorphous (333 K) 

0 crystallired at 283 K 

A annealed after crystallization 

0 

Figure 2. SAXS profiles of the blend 

2TM/T4 containing 40 wt % of PTHF 

homopolymer.

A 

o 

Phase Diagrams and Gelation Structures of B5Eg1B5 and BGE46B6 

Triblock Copolymers in Aqueous Solution 

T. Liu. C. IN. D. Liang and B. Chu (SUNY at Stony Brook) 

Poly(oxybutylene)-poly(oxyethylene)-poly(oxybtylene) (BEB) triblock copolymers 

are widely used in cosmetic and pharmaceutical industries. It is well known 

that such kind of block copolymers can form micellar structures in water because 

of the difference in the solubility of the hydrophobic B block and the hydrophilic 

E block. Compared with the large amount of studies on their micellization behaviors. 

the study at high polymer concentrations (< 10 mt%) is less reported and so 

far no phase diagram of these systems has been published. IVe used small-angle 

X-ray scattering technique (SAXS) at the X3A2 beamline of NSLS to study the 

gelation structures of two triblock copolymers (BsEglBs and B~E-~~BG). Before the 

gelation concentration, the scattering peak can be found at high polymer concentrations 

(50 wt% at room temperature). The relavent q value when the SAXS peaks 

occued showed a concentration dependence (q value increased with increasing polymer 

concentration) but no tenlperature dependence for both polymers, as shown 

in Figure 1. The gel regions were extremely small when compared with those of 

EPE (oxvethylene-oxypropylene-oxyet~lee) triblock copolymers. For BcE.teB6, 

this region was so small that we could locate it only at low temperatures (> 6 C) 

and very high polymer concentrations (< 90 wt%). probably due to the very short 

E block. SAXS study suggested that both form a kc (face-centered cubic) packing 

structure, as shown in Figure 2. 

," , 

C ' 

W o . %&=I W7 crn ' 

w, 't_=I Il-cn,' 

- -- 

"" 4. 

\--- ----_ 

" t ~~~~p_.~._~rp~~-,_~__ , 

::'_ ^',] :.< .& .., .

Supramolecular Structures of Complexes 

Formed by Poly(methacry1ate-co-N-isopropylacrylamide) Gels with 

Hexadecyltrimethylammonium Bromide 

X3A2 

S. Zhou, F. Yeh, B. Chu (SUNY @ Stony Brook) and C. Burger (Max Plank 

Institut fur Colloid & Interfaces) 

Small-angle X-ray scattering (SAXS) was used to investigate the nanostruc- 

ture formation by the interaction of slightly crosslinked negatively charged 

gels of poly(methacry1ate-co-N-isopropylacrylamide) (MAAINIPAM) with hex- 

adecyltrimethylammonium bromide (C16TAB). Three typical polyelectrolyte- 

surfactant complex (PSC) structures with Pm3n cubic, face-center cubic (FCC), 

and hexagonal closely packing (HCP) were observed when the charge content in 

MAAINIPAM copolymer gel was decreased, namely, Pm3n cubic was formed with 

gel charge content over 75%, FCC was formed with a charge content of 67%, and 

HCP was formed at a charge content of 50%. The unit-cell models for the three 

structures have been suggested. Figure 1 shows a typical Pm3n cubic PSC structure, 

consisting of spheres at BCC positions and a continuous network, both imbedded 

in a matrix. Figure 2 shows the three simulation scattering curves from the three 

different models, which almost matched the experimental scattering curves. The 

spherical microdomains in various of structures might be formed by the aggregates of 

C16TAB surfactant, which could be stabilized by the electrostatic and hydrophobic 

interactions between the surfactants and the gel network chains. With decreasing 

charge content in the polymer chains, the packing of microdomains became more 

compact. By decreasing the charge content of the gel to below 33%, no ordered 

structure was observed due to the weaker electrostatic interactions. 

The Crystal Structure of Rb6PbsCl16 and its Determination by X- 

ray Powder Diffraction using Anomalous Dispersion * 

H. P. Beck, M. Schramm, R. Haberkorn (U. of Saarland), R. E. Dinnebier (U. of 

Bayreuth) and P. W. Stephens (SUNY at Stony Brook) 

The hitherto unknown compound Rb6PbsC116 was synthesized by melting a stoichiometric 

mixture of RbCl and PbClz at 700°C and annealing for several weeks 

at 200°C. The metrics could be determined from a powder pattern, taken at a laboratory 

diffractometer, but the structure could only be solved by using synchrotron 

radiation. 

The compound Rb6Pb5Cll6 crystallizes in the tetragonal space group P4/mbm 

with lattice constants a=1171.41(4)pm and c=1103.11(6)pm. A Le-Bail fit enabled 

to extract about 400 integrated intensities from the powder pattern, which could 

be used for ab initio determination of the structure. This new type of structure [I] 

shows a large variety of different coordination polyhedra for the cations: columns 

of tetragonal prisms and antiprisms, capped trigonal prisms and a 6+2+2 polyhedron 

of a new type. Because the occupation factors could not be determined 

unambigously, two additional measurements near the Pb-Ls-edge were performed 

using anomal dispersion. A statistically distribution of Rb and Pb at only one of 

the cation sites with a ratio of 1:3 was found. There is no evidence for symmetry 

reduction by ordering. t] H. P. Beck, M Schramm, R. Haberkorn, R. E. Dinnebier and P. W. Stephens, 

Z. norg.Chem. (accepted). 

Figure 1. Typical unit-cell model for ~i~~~~ 2. ~ ~ SAXS ~ profiles i of ~ ~ l Figure 1. Struture of Rb6Pb5C116 (C axis points vertically). 

Pm3n cubic PSC structure f~rmed by the MAAINIPAM polymer gelICl6TAB 

the interaction of C16TAB with 

p 

complexes. The dotted lines present the 

fi charged MAA/NIPAM co~ol~mer gel. simulation curves from ideal models. * Work at the SUNY X3 beamline is supported by the Division of Basic Energy Sciences, 

-l U.S. Dept. of Energy (DE-FG0286-ER45231). 

X3B1

Fj 

rP I Anisotropic Strain of KICFO at LOW Temperatures " I X3Bll 

G.hI. Bendele and P.W. Stephens (SUNY at Stony Brook) 

The quadrivalent alkali fulleride salts A4Cfj0 (where A=K,Rb) are non-magnetic 

insulators with tetragonal crystal structure. \Ve have recently determined that they 

show no appreciable deviation from exact x=4 stoichiometry [I]. We have performed 

a low-temperature x-ray powder diffraction study on both K.tCfjo and Rb4Cm. 

The thermal expansion coefficients of the lattices of both compounds are 

of comparable magnitudes along and perpendicular to the unique axis (-1.2- 

2.5~10-~'A/K). Both compounds show an increase in the FWHLI of Bragg peaks 

with decreasing temperature and tlevelop an anisotropy, i.e., (001) peaks along the 

unique c axis are broader than (hkO) peaks perpendicular to c, indicating anisotropic 

strain in the lattice that increases as T is lowered. This effect is much stronger in 

KL1CGo than in Rb.lCGO, as Fig. 1 illustrates. 

Given the recent discovery of a two-dimensional cross-linked polymer phase of 

NaZtCGo [2] we suspect that this anisotropy is evidence of the onset of a phase 

transition into a similar polymeric phase, possibly at elevated pressure. For steric 

reasons, we expect snch polymerization to become harder with increasing cation 

size, consistent with the fact that the NafrCGo polymer is stable, K4Ct;o shows a 

large degree of anisotropic strain broadening, and Rb.lCGO exhibits alrrlost none. 

C.A. Kuntscher, G.RI. Bentlele, antl P.iV. Stephens. PRB 55. R336G (1997). 

G. Oszlrinyi et nl., Phvs. Rev. Lett. 78, 4438 (1997). 

0.16 

FWHM 

K4C60 

0 FWHM of (202) 

+ FWHM of (1 12) 

FWHMoI (211) 

50 70 100 T [K] 200 300 

Figure 1. 

^ \Vork at the SCSY 53 bearnline is supported by the Di~ision of Basic Ener,q\- Sciences. 

L*.S. Dept. of Energy (DE-FG028G-ER-15231). Research at SUSY is supported by the SSF 

under grant DSIR9.5-0132.5. 

I * NazKCso: Determining the Orientation of Fullerenes in the Lattice 

1 X3B11 

GAL Benclele, P.W. Stephens (SUNY at Stony Brook), and L. Forro (EPF, Lausanne) 

Na2KCfj0 is a cubic alkali fulleride at room temperature and above. but x-ray 

powder diffraction measurements show that it undergoes a slow phase transition into 

a symmetry-lowered ground state upon slow cooling. To determine the occurrence 

and geometry of interfullerene bonding it is crucial to obtain the orientation of the 

fullerene nlolecules in the lattice. 

After obtaining the monoclinic lattice parameters of the ground state (space 

group P21/a, a = 13.714 A, b = 14.627 A&, c = 9.380 A, 6 = 133.91') we have. 

without making any a-priori assumptions, performed a three-dimensional search 

over all possible orientations of the Csn ~nolecule. \Ve can specify that orientation 

using just three parameters, which are defined analogous to Enler angles: 6 and 8 

specify a point of contact along the shortened c axis and zi! specifies a rotation ahout 

c. In searching all (6,8,zlt) we find only one convincing rr~inirr~~~rn in the weightetlprofile 

R-factor R,,.,: a single carbon atom located on the c axis, with a rotation 

angle abo11t c of u = 77". To illustrate this, Fig. 1 shows R,,., vs. $ for several 

h~llerene points-of-contact. 

This compares in an interesting way to the case of isoelectronic NazRbCr;~ [I]: 

For that co~npound d antl H of the global minimum are identical, hut ~ is not, 

reflecting the fact that the interfnllcrenc bonding geonletry is itlcntical. 1mt the 

arrangcrnent of t,he chains in the lattice is not. 

[I] G.LI. Bcntlcle al., submitted to Phys. Rev. Lett. 

Figure 1. Plots of weighted-profile R-factor R,,., vs. rotation angle v in xa?KC~o 

for the following features of the fdlerene molecule pointing along the bonding c axis: 

+ Single C atom. o Center of donble bond. A Center of single bond. 0 Center of 

pentagon. T Center of hexagon. 

\\brk at the SL-SY X3 beamline is supported by the Division of Basic Energy Sciences. 

T.S. Dept. of Energy (DE-FG0286-ER43231). Research at SLTY is supportecl by the TSF 

under grant DlIR95-0132.5.

CD 

1 Effect of Charge State on Bonding gGometry: NaaRbCso 1 X3B11 

G.M. Bendele, P.W. Stephens (SUNY at Stony Brook), K. Prassides, K. Vavekis, 

K. Kordatos (U. of Sussex, UK), and K. Tanigaki (NEC Tsukuba, Japan) 

In order to determine the atomic structure of the ground state of the alkali 

fulleride NazRbCso obtained by slow-cooling [I] we have collected x-ray powder 

diffraction patterns at T=180K and T=20K1 with ~=1.15A and for 28=6"-50". 

In short, the unit cell of the low-temperature structure is monoclinic, space group 

P21/a, with lattice parameters a=13.711A, b=14.554& c=9.373A, ,8=133.53" (at 

T=180K). In this cell, we find that the fullerenes are connected along c by single 

carbon-carbon bonds [2], in contrast to the ground state of the otherwise similar 

RbCso system [3], in which the fullerenes are linked with two bonds via [2+2] 

cycloaddition. See Figures 1 and 2 for an illustration of the differences. 

The question why Na2RbCso links fullerene molecules with a single bond, while 

the latter does so with two carbon-carbon bonds is very important. After excluding 

possible steric and kinetic reasons for this difference in bonding geometry we con- 

clude that it is the charge state of the fullerene that plays a decisive role, causing 

(C&), to favor cycloaddition and (C&), to favor single carbon-cabon bonds. 

Details on both the data analysis and our conclusions with respect to the charge 

state can be found in [2] or in G.M. Bendele et al., in Proceedings of the IWEPNM 

97 Kzrchberg/Tyrol (World Scientific 1997). 

Work at the SUNYX3 beamline is supported by the Division of Basic Energy 

Sciences, U.S. Dept. of Energy (DE-FG0286-ER45231). Research at SUNY is sup- 

ported by the NSF under grant DMR95-01325. Work at Sussex is supported by the 

EPSRC. 

1 K. Prassides et al., J. Am. Chem. Soc. 119, 834 (1997). 

2 G.M. Bendele et al., submitted to Phys. Rev. Lett. 

3 P.W. Stephens et al., Nature (London) 370, 636 (1994). 

I1 

Figure 1. Atomic structure of the Figure 2. Atomic structure of the RbCso 

NaaRbCso polymer derived here. polymer (from [3]). 

Powder Diffraction Structure of Fluorenylsodium 

R. E. Dinnebier (U. of Bayreuth) and F. Olbrich (U. of Magdeburg) 

The crystal structure of the organometallic compound fluorenylsodium 

(NaC13Hg) has been solved ab initio. The compound crystallizes in the hexag- 

onal space group P 63/m (No. 176) with a = 9.2828(1), c = 19.1613(2), V = 

1429.93(2)& and d = 1.197 g cmP3. Data collection was carried out at room tem- 

perature using a wavelength of 1.14966 Afrom double Si(ll1) monochromator and 

Ge (111) analyzer. The 20 range used for the Rietveld refinement was 5.0 < 20 < 

50.0". All positions of the carbon and sodium atoms were found by a combination 

of direct methods, partial Rietveld refinements and difference Fourier analysis. The 

indenyl ring was refined as a rigid body and the hydrogen atoms were calculated 

in idealized positions. The actual Rietveld plot yields to R-wp= 5.6%, R-p= 4.3% 

and R-F2=8.2%. Figure 1 shows part of the coordination spheres around the two 

different sodium positions of NaC13Hg. The NaC13Hg units are connected in two 

dimensions pependicular to the crystallographic c axis. Within this network, the 

Na atoms are either hapto5 or hapto6 coordinated by three fluorenyl rings. The 

layers themselves are connected by van der Waals forces only. 

SCHAKAL 

X3B1 

Figure 1. Part of the structure of NaC13Hg showing the two different coordination 

spheres around the two sodium sites. The two Nal atoms are aligned along c-axis. 

Hydrogen atoms have been omitted for clarity.

U1 

o 

Study the Phase Diagrams of L64/water/CdC12 Complex Systems 

by SAXS 

T. Liu, C. SVu, D. Liang and B. Chu (SUNY at Stony Brook) 

The design of new inorganic materials with special structures has become an 

important area in materials science. Triblock copolymer micelles can be used as 

a kind of potential templates for synthesizing inorganic compounds with special 

nanostructures. To find out proper synthesis conditions, the phase diagrams of 

polymer/water systems in the presence of specific inorganic salts have been inves- 

tigated. L64 (poly(oxyethy1ene)lB-poly(oxypropylene)30-pol oxyethylene)l3) is a 

widely used commercial triblock copolymer and the phase diagram of L64/water 

system has been carefully characterized. In this study, wc found that in the pres- 

ence of CclC12, a water-soluble salt, the phase diagram of L641water changed greatly. 

Cloud-point temperatures and gelation concentrations went down when compared 

with the pure L64/water system. Also, a two-phase region (thick gel) appeared 

at high salt concentrations, as shown in Figure 1. Small-angle X-ray scattering 

(SAXS) at the XBA2 beamline (NSLS) revealed that some new structures, like the 

bcc (body-centered cubic) strclltllre which has not been found in the L64lwater 

systern, have been observed clue to the introduction of CdC12, as shown in Figure 

Q 

a %, d 

La 

Figure 1. The phase diagram of 

LG-l/~vater/CclCl~ system with molar ratio 

LG-l:CdC12=1:5.76. Several separated 

gel regions were found. 

X3A2 

Figure 2. SAXS 

curve of L64/nater/CdC12 system with 

molar ratio L61:CclClz=1:3.76. weight 

ratio L64:water=82:18. The scattering 

profile indicates bcc (bod>--centered cu- 

Formation of Clay h4inerals Replacing Diatom Cells in Amazon Delta 

Sediments 

P. Michalopoulos, R. C. Aller. P.W. Stephens (SUNY at Stony Brook) 

X3B1 

We investigated the potential growth of clay minerals in association with diatom 

cells found in Amazon delta sediments using x-ray powder diffraction. Processes 

that lead to the in situ formation of clay minerals in marine sediments are important 

for global geochemical cycles and the composition of seawater Sample preparation 

involves separation of individual diatom cells from the sediments. grounding of less 

than two hundred cells and mounting on a Si (1.0.0) wafer X-ray powder diffraction 

patterns from these samples (Fig. 1 show the presence of characteristic clay 

mineral peaks together with pyrite (FeS2 1 and gypsum Pyrite originates from the 

decomposition of the diatom organic matter through sulfate reduction. Figure 1 

shows the 7.17 peak, typical of clay minerals such as kaolinite (S~.IA~.IO 10 (OH)8). 

These results indicate that the biogenic silica has acted as a substrate for the formation 

of new clay minerals. These co~lcl~lsions have been corroborated with other 

techniques such as SEhI. TEhI and electron microprobe studies which show that the 

new clay nlinerals are replacing the siliceous frnstule of tliatorns through tlissolutionprecipitation 

reactions. Ttie newly formed 7.17 phase is one of several authigenic 

mineral phases that form on these substrates. Sorne phases remain ~n~tletectetl tluring 

the X-ray analysis clue to poor crystallinity and/or very srnall crystallite size. 

1 i.17 (clay mineral phase) 

I 

8 I I I 

20 30 40 

lo 2 Theta 

bic)structure. Figure 1. The 7.17 Angstrom peak represents the nen-ly formed clay mineral phase.

Na4CGo: An Alkali Intercalated Two-Dimensional Polymer 

A remarkable feature of C60 molecules is that they may form bonds with each 

other leading to a variety of crystal structures and physical properties. Initially the 

Diels-Alder type [2+2] cycloaddition was considered as the exclusive mechanism for 

bond formation. Recently a different type of interfullerene bond was detected in 

a metastable dimerized phase of AC60 (A=K, Rb) where dimer anions are formed 

by joining single carbon atoms [I]. This finding suggested that the formation of 

single bonds is not an isolated example but a general trend at higher charge states 

of the fullerene anions. In a systematic search, the long-missing Na4C6o phase 

has been identified by Rietveld analysis of synchrotron powder diffraction data 

121. Its monoclinic structure (space group: I2/m, lattice parameters: a=11.235A1 

b=11.719A, c=10.276A, P=96.16") is based on polymer planes of Cso where each 

molecule forms four single bonds within the plane. This compound is not only the 

first fulleride polymer with such bonds, but also the first two-dimensional polymer 

which is naturally intercalated with alkali ions and can be synthesized at ambient 

pressure. 

G. Oszlanyi et al., Phys. Rev. B54, 11849 (1996) 

G. Oszlanyi et al., Phys. Rev. Lett., 78, 4438 (1997) 

Figure 1. 

- 

X3B1 

G. Oszlanyi, G. Faigel (Res. Institute for Solid State Physics) and G. Baumgartner, 

L. Forro (Ecole Polytechnique Federale de Lausanne) 

Measurement of Coherent Scatter Form Factors in Tissues in Sup- 

port of Monte Carlo Simulation of Mammography * 

D. E. Peplow and K. Verghese (NC State University) 

I X3Bll 

A team of physicists, engineers and doctors from NC State University, UNC, 

NSLS and IIT is currently investigating the use of monochromatic synchrotron ra- 

diation for mammography to obtain to an image with less scatter and higher contrast 

than conventional mammograms. In support of these experimental studies, Monte 

Carlo calculations are being performed to evaluate the new system and investigate 

its potential performance. 

Most Monte Carlo calculations use the free-gas model for determining the co- 

herent scatter angular distributions, which does not include intramolecular or in- 

termolecular interferences. For amorphous materials, this approximation does not 

hold at low values of x (x = 2 sin $). The coherent scattering form factors of these 

materials show broad peaks &d mist be measured. 

The form factors of five tissues and two plastics materials (relevant to mammog- 

raphy phantoms) were derived from scattering measurements made on the powder 

diffraction line X3B1 with the assistance of Dr. P. W. Stephens. Due to the difficul- 

ties of using human tissues, fresh beef and pork samples were substituted. Shown 

in Figure 1 is the coherent scattering form factor of water measured at the NSLS 

with a measurement made by Narten (Report ORNL-4578, 1970) using an X-ray 

tube spectrum. Figure 2 shows the measured form factor of pork fat with its free- 

gas approximation. The form factors are being incorporated into the Monte Carlo 

model to simulate images from the new digital mammography current digital mam- 

mography machines and the new synchrotron-based system. 

Figure 1. Form factor of water: mea- 

sured at the NSLS (solid) and Narten's 

measurement (dashed). 

Figure 2. Form Factor of pork fat: mea- 

* Funding for this research was provided sured at the NSLS (solid) and the free- 

through the US Army Breast Cancer Re- gas approximation (dashed). 

search Program

P 

cn 

Rotational Order in CO Intercalated C/,jO Crystals * 

S. vansmaalen, R. E. Dinnebier (U. of Bayreuth, Germany), I. Holleman, G. von 

Helden, G. Meijer (U. of Nijmegen. The Netherlands) 

The structure of (CO),Cfio(x= 0.67) has been determined by high resolution 

X-ray powder diffraction [I]. Crystallographic data are: space group P a -3, a= 

14.0605(1) A. The data were collected in a closed cycle helium cryostate at 25 K with 

a wavelength of 1.15030(1) Ausing a double Si(1ll) monochromator and Ge(1ll) 

analyzer in a 2 0 range of 5.0 < 2 0 < 75.0 for 20 seconds per step. The structure 

was solved by rigid body Rietvelcl refinement and difference Fourier analysis. CO is 

found distributed over six equivalent orientations on the octahedral sites of the cubic 

clocsed packed structure of Cco. The Cc;o molecules are orientationally ordered in 

almost excl~isively the major orientation. There is evidence for a weak electrostatic 

interaction between Cso antl (CO),. 

[I] S. van Smaalen, R. E. Dinnebier. 1. Hollemann, G. von Helden, antl G. hIeijer, 

submitted. 

Figure 1. \.iew of the unit cell of (CO),Cso showing the 6-fold disordered CO 

molecules near the octahedral sites of the cubic closed packed structure. 

\Vork at the SUSY S3 beamline is supported by the Division of Basic Energy Sciences. 

U.S. Dept. of Energy(DE-FG0286-ER43231) 

X3B1 In Situ Diffuse Scattering Studies of Ag(ll1) During Low Temperature 

Homoepitaxy * 

X3B2 

W.C. Elliott. P.F. hliceli (U. of Missouri-Columbia), and P.nT. Stephens (SUNY 


The morphology of a surface during epitaxial growth is determined by the kinetic 

mechanisms which affect the incorporation of deposited atoms into the crystal sub 

strate. We have studied the lateral structure of a kinetically roughened Ag(1ll) 

surface during homoepitaxy at 200K to further understand the effect of a large 

stepedge barrier to surface diffusion upon the resulting surface morphology. 

AIeasnrement of surface diffuse x-ray scattering in reflectivity geometry is a means 

of obtaining this lateral structure: scans transverse to the specdar reflectivity near 

the out-of-phase position provicle excellent sensitivity to the developing lateral structure. 

As the surface roughens during deposition, the central specular peak tliminishes 

while diffuse scattering appears and broadens with increasing coverage(a). 

This diffuse scattering is a measure of the mean terrace length on the surface 

and can be described by a power-law over two tlecades in coverage(b). Near 16hIL, 

a second diffuse peak appears which narrows with increasing cowrage. This new 

peak is attributed to the separation between tlevcloping mounds which coarsen with 

increasing coverage. 

Mound Separation 

Mean Terrace Length 

- 

-4 -2 0 2 4 0.1 1 10 100 1000 

o (deg.) 8 (monoluyers) 

Fignre 1. 

^ Supported by SSF (D1IR-9202528 and DlIR-9623827). 1IISCOS \;under USDOE 

(DE-FG02-90ER15.127) and the SL3Y X3 beamline is supported by USDOE (DE-FG02- 

86ER45231).

Structure Of a Cre Recombinase-DNA Site-specific Recombination 

Synapse 

F. Guo, D. N. Gopaul, and G. D. Van Duyne (U. of Penn.) 

Cre recombinase catalyzes the reciprocal exchange of DNA strands between 34- 

base pair loxP sites during site-specific recombination. Using diffraction data mea- 

sured at the X25 and X4A beamlines, we have determined the 2.4 A crystal struc- 

ture of a covalent intermediate in the Cre-loxP reaction, where the recombinase 

has cleaved and formed 3'-phosphotyrosine linkages to its DNA substrates. Four 

recombinases and two DNA substrates are arranged in a pseudo-fourfold symmetric 

tetramer that represents a site-specific recombination synapse. 

Parent data and two heavy atom derivative data sets for this structure were 

measured at the X25 beamline. One derivative was made from selenomethionine- 

substituted Cre recombinase, with 22 anomalous scatterers in the crystallographic 

asymmetric unit. Data were measured at a single wavelength corresponding to a 

maximum of f" and the resulting anomalous diffraction signal led to strong crys- 

tallographic phasing power. The second heavy atom derivative made use of an 

iodine-containing DNA substrate. The selenomethionine derivative was also used 

for a three-wavelength anomalous diffraction measurement at the X4A beamline. 

Together, the heavy atom diffraction data from the two beamlines led to a readily 

interpretable image of the electron density. 

I In situ Surface X-ray Diffraction Study on Ru02 (100) Single Crystal 1 X6B I 

Y. Chu, J. Tanzer, H. You, and Z. Nagy (ANL) 

Ruthenium dioxide has been known to exhibit unusually large pseudo- 

capacitance, and it is appealing candidate material for temporary energy storage 

device for advance battery applications. This ultra capacitance has been attributed 

to the change of the oxidation state of the Ru atoms at the electrochemical inter- 

face, yet the structural change due to the valency shifting has not been understood 

well. 

In situ surface x-ray diffraction experiment was performed on as-grown 

RuOz(100)single crystal samples. The cyclic voltammetry of the sample is shown 

in Fig. la. The cathodic peak just before the hydrogen evolution is due to the 

reduction of Ru atoms from valence 4+ to 3+, and the anodic peak is due to the 

reverse reaction. The charge transfer obtained from CV indicates the redox reaction 

is limited to about a single monolayer. Fig. Ib shows that the intensity at (1.5, 0, 

0) undergoes a significant change at the same potential where the reduction occurs, 

suggesting some modification of the surface structure due to the reduction. The 

reflectivity data shown in Fig 1.c reveal that the reduced surface at -200 mV has a 

very different surface structure from the oxidized surface at 460 mV (open circuit 

potential). 

Preliminary fitting analysis indicates that the top Ru layer spacing is significantly 

expanded when reduced, while slightly contracted when oxidized. The expansion 

of the surface layer spacing may be due incorporation of protons into the lattice to 

accommodate the shift in the oxidation state of Ru atoms. 

110l . , . , . , . , . , I 

4W -am 0 2W 4W 6W 

Potential (mV) vs. AdAqCI 

H (reciprocal lattice units) 

Figure 1. A) Cyclic voltammetry of RuOz(100) in 0.5 M HzS04. B) Intensity at 

(1.5, 0, 0) vs. potential. The direction of potential scan is indicated by arrows. C) 

Reflectivity data at 460 mV (open circuit potential, solid squares) and at -200 mV 

(open circles). The dotted lines are fits.

tP 

Gl 

JA 

Levitation Apparatus for Structural Studies of High Temperature 

Liquids Using Synchrotron Radiation 

X6B. 

X25 ' 


Research, Inc.), h.1. A. Beno: S. Ansell, and D. L. Price (ANL) 

A new levitation apparatus coupled to an synchrotron-derived x-ray source has 

been developed to study the structure of liquids at temperatures up to 3000K. The 

levitation apparatus employs conical nozzle levitation using aerodynamic forces to 

stably position solid and liquid specimens at high temperatures. A 270 IVatt, COz 

laser was used to heat the specimens to desired temperatures. Two optical pyrometers 

were used to record the specimen temperature, heating curves and cooling 

curves. Three video cameras and a video recorder were employed to obtain 

and record specimen views in all three clin~ensions. The levitation assembly was 

supported on a three-axis translation stage to facilitate precise positioning of the 

specimen in the synchrotron radiation beam. The levitation system was enclosed in 

a vacnum chamber with Be windows, connections for vacuurn antl gas flow. ports 

for pyrometry, video and prcss~~re measurements. The ncuurn system incll~tled 

automatic pressure control antl multi-channel gas flow control. A phosphor screen 

coupled to a high-resolution video rriicroscope provitletl images of the x-ray beam 

antl specimen shatlow which were used to establish the specimen position. The 

levitation qpparntl~s was integrated with x-ray tliffractometers located at X6B antl 

X25 bcamhncs at the National Synchrotron Light Source. X-ray structural measnrements 

have been obtained on a ruunher of materials including -41203. Ni. Si, 

Gc. and other metallic antl cerarriic materials in the liquid state. 

S. Krishnan, ct al.. Rev. Sci. lnst7~~rn, 68, p. 3512 (1997). 

X-Ray Investigation of the Transformation of Crystal Structures In- 

duced by Mo Seeding Layers 

X6B 

C.H. Lee (Tsing-Hua U..Taiman), J.C.A. Huang and Y.M. Hu (Cheng-Kung U.. 

Taiwan), and hl. Shih (ChungHsin U., Taiwan) 

Epitaxial permalloy thin films were prepared on the sapphire substrates (1-100) 

via hIo seeding layer. The structure of the epitaxial permalloy film is stronly related 

with the thickness of the h'Io buffer layer. In details, the permalloy is dominated 

in (111) in the plane-normal direction when the hIo layer is thinner than 2A. The 

preferred orientation is switched to (220) when the hIo buffer layer is from 2A 

to 20A. The permoally thin films are orinetated in (211) directions after 20A of 

hIo laver is deposited. For the in-plane direction, all the permollay(0-22) surfaces 

are locked in the hIo(-1ll)direction or sapphire(0001) directions. For all the good 

expitaxial films, the permalloy are in a twin fcc structures with a stacking fault 

along the permalloy(-1ll)or permalloy(1-1-1) direction and the domain size is 2011 

to 40A depending on the thickness of hIo laver. The coexisterice of permalloy(220) 

together with permalloy(211) from 211 to 20A can be interpreted by the dropletlike 

hlo thin film on the surface of sapphire. The edge surface of the hIo droplets 

stablize the permalloy(220) structure on the s~~rfacc of sapphire. After 20A of hIo 

deposition, the SIo islands coalesced antl a pnrc perrnalloy(211) struct,we prevails.

p 

C1 

In Situ Study of the Growth of OTS Self-Assembled Monolayers on 

Silicon I x6B I 

A.G. Richter, M.K. Durbin, C-J. Yu, and P. Dutta (Northwestern U.) 

Self-Assembled Monolayers (SAMs) have been extensively studied using many 

techniques, including X-ray reflectivity and diffraction. Although much is known 

about the few systems that self-assemble, very little is known about the process of 

deposition and film formation. Several studies have been made of SAMs of octade- 

cyltrichlorosilane (OTS), and these have given us some insight into this problem, but 

they have been performed ex situ. Recently we have performed in situ experiments 

on the formation of OTS SAMs using X-ray reflectivity. 

X-ray reflectivity requires contrast in the electron density profile, but the densities 

of most organic materials fall within a narrow range. We used heptane, which 

has a low density (N 0.33 times the density of silicon) as our solvent. Typical 

monolayer densities are 0.4-0.5 times silicon density. Since the contrast is still low, 

the reflectivity minima are not as pronounced as for ex situ systems, but the minima 

are obvious. A solution concentration of 0.0001% was used. Film growth occurred 

too rapidly at higher concentrations to allow us to study the early stages of growth. 

We have found that the film formation has at least three different modes of 

growth. During the first stage, the film-solution interface is rough and the film 

thickness is low. This is probably due to the molecules having a range of tilts, 

most of them large. The second stage of growth begins after about 5 hours at 

this concentration. During this stage, the film thickness is roughly constant and 

is about that of a fully extended molecule (2.3nm). However, the modeled density 

profiles suggest that the film is still loosely packed and that some of the molecules 

are tilted. Over time, the film becomes denser and more uniform. This most likely 

occurs because more molecules are deposited, increasing the density and forcing the 

surrounding molecules to stand up. This stage lasts for about 5 hours, after which 

the molecules are all mostly untilted. In the last stage, the film changes minimally; 

only the film-solvent interface becomes slightly sharper. 

30 

Electron Density Profile Contours 

OTS an Silicon, In Sit" 

Solution j 

Time (Hours) 

Figure 1. A contour plot of the electron density profile of OTS on silicon over time. 

Note that 0.33 is the solvent density (in units of silicon = 1.0). The film dioxide 

layer ranges from 0.75 to 0.37. The silicon dioxide layer ranges from 1 to 0.75. 

I Strong Negative Thermal Expansion in Siliceous Faujasite * I X ~ I A 

M. P. Attfield and A. W. Sleight (Oregon State U.) 

Negative thermal expansion has received a lot of interest recently, with the dis- 

covery of strong isotropic negative thermal expansion in ZrW208 (1) over a broad 

temperature range. An apparent requirement for an oxide material to have strong 

intrinsic negative thermal expansion is that it has an open framework structure 

with two coordinate oxygen atoms. Zeolites are a group of compounds whose struc- 

tures fulfill the aforementioned requirements. Indeed, computer simulations have 

predicted that some zeolites should exhibit negative thermal expansion (2). The 

thermal expansion of siliceous faujasite was investigated,thus avoiding the compli- 

cations associated with the extra-framework cations and greatly reducing the water 

content of the zeolite. 

Synchrotron data were collected on a dehydrated sample of zero defect dealumi- 

nated Y (ZDDAY) at seven temperatures between 25.16 and 297.95 K to determine 

the unit cell constant and structure as a function of temperature. X-ray data above 

298 K were collected on a laboratory INEL XRG 3000 diffractometer. 

An approximately linear decrease in cell dimension is seen over the entire tem- 

perature range (Figure 1)with an overall coefficient of thermal expansion of -4.2 x 

10r6 Kpl . The results from the Rietveld refinements indicate that the bridging 

Si-0-Si angles display no significant changes over the temperature range analysed 

and that the constituent Si04 tetrahedra of the structure may be considered as 

rigid tetrahedra over this whole range. These results lead us to believe that the 

negative thermal expansion of this material is related to the harmonic transverse 

vibrations of the 2-coordinate bridging oxygen atoms within the structure. These 

vibrations lead to coupled rotations of the essentially rigid tetrahedra making up 

the structure of the zeolite. The increased magnitude of these transverse vibrations 

with temperature results in a decrease in the average Si-Si non-bonding distance 

and the negative thermal expansion observed.[l J. S. 0 . Evans, T. A. Mary, A. W. 

Sleight and T. Vogt, Science, 272, 90 (1996). f2] P. Tschaufeser and S. C. Parker, 

J. Phys. Chem., 99, 10600 (1995). 

Figure 1. Cell parameter as a function of temperature for siliceous faujasite. 

* We thank G. J. Ray, Amoco Chemical Company, for provision of the dealuminated 

zeolite-Y sample. This work was supported through DOE and through NSF grant No. 

DMR-9308530.

m 

C, 

Structural Changes, Clustering and Photo-induced Phase Segregation 

in Pro.~Ca0.3Mn03 * 

The structural properties of Pro.7Cao.3R,InO3 mere studied by x-ray synchrotron 

and neutron powder diffraction as a function of temperature (15 < T < 300 K), and 

as a function of x-ray fluence at 15 and 20 K. The temperature evolution of the lattice 

parameters and of the superlattice reflections is consistent with the development 

of charge and orbital ordering below Tco -- 180 K, followed by antiferromagnetic 

ordering below T!v 140 K. Below Tc -- 120 K. the rnagnetic structure develops 

a ferromagnetic component along the a ais on the hIn ions. The observation in 

Pro.7Cao.3hIn03 of significant lattice strain below Tco, as well as the development 

of a ferronlagnetic component to the magnetic structure at Tc, can be interpetetl 

in terms of the presence of ferromagnetic clusters with an associated lattice distortion 

from the average structure. At low temperatnres, exposure to the x-rav beam 

produces a phase segregation phenomenon, whereby t,hc ferro~nagnetic droplets coalesce 

into larger aggregates. Further exposure results in a gradual melting of the 

charge-ordered phase antl the for~nation of the ferrornagrietic ~nctallic phase recently 

reported by Kiryukhin et nl. (Nature 386, 813 (1997)). The ferronlagnetic phase 

has a significantly srrialler n lattice parameter antl unit cell volume (AV/V - 0.4%) 

than that of the charge-ordered phase. 


Figure 1. Lattice parameters and unit 

cell volume vs. temperature 

X7A 

D. E. Cox (BNL), P. G. Radaelli (ILL, Grenoble), M. klarezio (MASPEC-CNR, 

Parma), and S.-W. Cheong (Lucent) 

28 (degrees) 

* \Vork at BNL was supported by the 

Figure 2. E~olution of the photo- 

C.S. Dept. of Enere. Division of llateriferromagnetic 

phase ,vith x-ray 

als Sciences under Contract So. DE-AC02- fluence 

76CH00016 

High Pressure and Low Temperature Study of the LTO to LTT Phase 

Transition in La(l.4751Nd(o.41Sr(o.125~C~~0 

X7A 

L I I 

hI. Crawford, R. Harlow, E. RIcCarron (DuPont). S. Tozer (Florida State U.). and 

D. Cox (BNL) 

We have continued our high-pressure. low-temperature x-ray diffraction studies 

of the LTO (Bmnb) to LTT (P421ncm) structural transition in doped lanthanum 

cuprates. La[l.,175)Nd~o.,t) Sr(o.lz5) Cu0'~ undergoes this structural transformation at 

a temperature of 80 K at ambient pressure, similar to the transition observed in 

La[l.87s)Ba(o.125)Cu0.1. Results from our previous study of the latter material had 

shown that a Pccn phase, intermediate to the LTO and LTT phases, was initially 

stabilized by pressnre. The LTO to Pccn transition temperature was observed to 

decrease slowly mith increasing pressure at pressures below 15 kbar, but at pressures 

greater than 30 kbar only the HTT phase exists from room temperature to 

10 K. At pressures near 20 kbar the Pccn phase vanishes antl only the HTT phase 

remains, but the small orthorhombicity in t,his pressure range precludes precise 

structural determinations. The suppression of the structural phase transitions under 

pressure generally correlates with previous reports that the Tc of this material 

increases under prcssllrc, but only as high as 15 K at pressures of 20 - 25 kbar, 

where our strllctural data are consistent with the material still having Pccn synlmetry. 

Since even the ambient pressure orthorhombicity of La(l.x7a) Bit(0,125) CIIO'I 

is relatively small (making these subtle structural transitions very difficult to follow), 

we tlecitlcd to perform the same experirnerlt using a cornpountl mith similar Tc 

characteristics, but mith an orthorhornl~icity twice that of the Ba-doped mattrial: 

La~l..17;)Ntl(o..l~Sr(o,12a,C~~0~l. 

This stlltly was perforrnetl using a hIcrrill-Bnssrtt 

tliamontl anvil cell with a 41 methanol to ethanol pressure metliun~. The cell was 

pressurized to 16 kbar antl the stutly was carried out using a focused monochromatic 

(0.6967) heam and a positiori- sensitive cletector. Contrary to the results found for 

the Ba-doped sample, the LTO - LTT transition temperature of the Ntl/Sr-tloped 

material was fourrtl to increase with pressure. This result is consistent with the ob servation that the two materials have ambient pressure thermal expansion anorna1ic.s 

of opposite sign at the LTO - LTT transition. It would be interesting to develop a 

Landau theory for the the temperatl~re/pressllre phase diagrams of these materials 

to qnalitatively account for this difference in prtssure tleprntlence. Superconducting 

Tc mrasurernents for the Ntl/Sr-doped phase under pressure are now ~lntlerlvay.

46 

C7 

Energy-dispersive Surface X-ray Scattering Study of Thin Ceria Overlayer 

on Zirconia * I x7A I 

W. Dmowski (U. of Pennsylvania) 

We have studied the structure of ultra-thin CeOz overlayer on single crystals of 

Y stabilized cubic zirconia (ZrOz) by energy dispersive surface x-ray scattering [I]. 

Three different crystallographic surfaces, (OOl), (011) and (Ill), were examined. In 

addition, we performed in-situ temperature study of a sample with (001) surface. 

We showed that on (001) oriented samples [1,2] CeO2 formed an epitaxial thin film. 

The results obtained for the (011) and (111) oriented crystals are qualitatively the 

same. Fig. 1 shows two dimensional plot of the scattering intensity in the Q,-Q, 

plane. Q, is offset by 0.05 A-' to avoid a strong Bragg peak and Q, is almost 

parallel to the [-1101 direction. The edge like feature at Q,=3.4 k1 is a truncation 

rod of a zirconia (-220) reflection. The broad pattern centered at Q,=3.3 A-' and 

extending well in Q, corresponds to the (-220) reflection from the ceria overlayer. 

Depth profiling of Y and Zr fluorescence lines shows depletion of yttrium starting at 

depth 230 A and then surface enrichment. We have studied the surface diffraction 

from the (001) sample with deposited cerium metal, in-situ, in the temperature 

range 100-800°C. At the temperature of 420°C we start to see weak diffraction 

from the (400) ceria peak at ~,=4.6kl which corresponds well to the ceria lattice 

constant. The lateral coherence length of the ceria film is only about 20 A at this 

temperature. At 620°C the lateral coherence length is increased to 46 A. Finally 

after prolonged annealing above 700°C Ce diffuses into the bulk of the zirconia 

crystal and the (400) diffraction peak gradually disappears. 

W. Dmowski, T. Egami, R. Gorte and J. Vohs, Physica B 221 (1996) 420. 

W. Dmowski, S. Fu, T.Egami, R. Gorthe and J. Vohs. MRS , vol. 401, p. 

115, (1996). 

Figure 1. Diffracted intensity in Q,-Q, plane for (111) sample oriented with [-1101 

direction along the scattering vector near the (-220) reflection. 

X-Ray Diffraction of CMR Sample Lal.4Srl.6Mn207 1 X ~ I A 

W. Dmowski and T. Egami (U. of Pennsylvania) 

We have examined powder diffraction of Lal.4Srl.6Mn207 samples. First sam- 

ple was prepared using "powder" processing while the second one was grown as 

a single crystal and later crushed to make fine powder. These samples have been 

examined by neutron diffraction and showed different temperature dependence of 

lattice parameters. It was observed that metal-insulator transition temperature and 

charge doping levels were different. This suggested inhomogeneous distribution of 

Sr atoms such as preferential occupancy of La in (0,0,1/2) position. Since neutron 

scattering lengths for most elements are very similar we used x-ray diffraction to 

enhance scattering information from heavy elements. Experiment was done below 

the absorption edge of strontium in reflection geometry. Intensity was corrected for 

background and volume changes. We focused on low Q data since they are most 

sensitive to ordering. The results from GSAS refinement show that for "powder" 

sample minimum of R-factor is achieved for 0.6 occupancy of La in (0,0,1/2) site 

(complete disorder corresponds to 0.467). The refinement for "crystal" sample is 

more complex. The R-factor stays above 28% due to systematic deviations in in- 

tensities for (OOL) reflection. This is illustrated in the Figure 1. This suggests that 

"crystal" sample is affected by stacking faults like intergrowths in this layered struc- 

ture. The intergrowths are likely to localize charge reducing overall doping level. 

Due to poor R-factor, refinement is not sensitive to La ordering showing similar 

R-factors between 0.45 and 0.7 of La occupancy in (0,0,1/2) site. 

2-Theta, Beg XlOE 1 

Figure 1. GSAS refinement of Lal.4Srl.6Mn207 powder. Sample was prepared by 

* This research was supported by the U.S. Dept. of Energy and the National Science 

Foundation through the Automotive Initiative Grant DE-FGO2-96ER14682.AO00. 

crushing single crystal sample,

The Crystal Structure of Bi4Au2OI4: The Use of a Siemens CCD 

Detector with Short-Wavelength Radiation 

X17B1 

R. Harlow (DuPont)? J. Parise (SUNY at Stony Brook), J. Phillips and C. Campana 

(Siemens), and J. Hanson (BNL) 

The determination of the structure of Bi4Au2014 presented two difficulties: absorption 

(mu for hIoKa is approximately 1050 cm-1) ancl the presence of a superlattice 

which is 4x the sublattice. Three sets of data have been collected on crystals of 

this compound: with in-house hIoKa radiation using a Siemens CCD ancl a Rigaku 

image-plate system, and with 0.185 A synchrotron radiation (where mu is reduced 

to approximately 30 cm-1) at beamline X17B1. also with a Siemens CCD. At this 

point, the subcell structnre (tetragonal, a = 8.676 and c = 5.832 A, in space group 

P.1212) has been solved and refined using the synchrotron data to an R value of 

10.3% using 2094 reflections to a resolution of ca. 0.3 A. All of the atoms mere 

refined with anisotropic thermal parameters, with special attention given to those 

of the oxygen atoms which arc the presumable source of the snperlatticc. One of 

the oxygen atoms was fol~ncl to be disordered over two sites: it is believed that this 

oxygen will be ortleretl in the supercell where the c-axis is doubled. This type of 

disorder was expected because the Bi site in the snbcell contains a mixture of Bi+'' 

and ~i". Presumably, the latter arc also ortleretl in the supercell. The source 

for doubling the cell along the a-b tliagonal has not yet been tlctcrmirietl. Using 

the in-house tlata, only thc ticavy atoms could be refined with anisotropic thermal 

parameters and somc of tlicse ellipsoitls were not very realistic. Also, the tlisortler 

of the one oxygen atom was not visible frorrl the in-ho~~se tlat,;~. \\;ark continues on 

rrlotlelling the supercell strnct~lre, but the benefits of using thc (almost) absorptionfree 

data from the synclirotron/CC:D corrlhination arc already clearly evitlerit. 

I High Pressure Powder Diffraction Studies of Zeolite Na-A I X ~ I A 

J. A. Hriljac, I. Gameson and P. P. Edwards (U. Birmingham, UK) 

h4icroporous solids, such as the aluminosilicate zeolites, are characterized by a 

large and regular pore system of molecular dimensions. They are used widely in 

several industrial applications including catalysis, ion-exchange, and gas separations. 

Surprisingly, their structural properties as a function of pressure appear to 

be mostly unexplored. The only literature reports are for silica sodalite to 1.28 GPa 

[I], ZShI-5 to 4.0 GPa [2], and scolecite (calcium natrolite) to 10 GPa. 

In this work, the high pressure powder X-ray diffraction patterns of the sodium 

form of zeolite-A were examined. The sample was loaded in a diamond anvil cell 

with a small amount of NaCl ancl a ruby chip, and then a 4:l methanol/ethanol solution 

acltled as a pressure transmitting medium. Pressures were measured using the 

ruby fluorescence technique. The beam line was configured with a sagitally focussing 

bent silicon (220) monochromator and a PSD. The wavelength was 0.6969(1) .ias 

determined via calibration against a silicon standard. Diffraction data mere measure 

from ca. ambient pressure to 7.85 GPa. 

A typical diffraction pattern is shown in Figure 1. Accurate peak positions were 

determined by the least-sqnares fitting of individl~al lines, and thc values of the cubic 

lattice parameter were then tleterrninetl by least-sqnares fitting of these values. A 

graph of the refined lattice parameter us. pressure is shown in Fig~~rr, 2. From these 

tlata a value for the bulk rr~otlulus of 57.5(26) GPa has been tleterrninetl. Further 

details of the strllctural changes are difficult to determine from the lirrritetl quality 

tlata obtained, bllt these will be further investigated in fnture studies. 

References 

/I] K. F~lttrrer, \V. Deprneier, F. .4ltorfer, P. Behrens, and .J. Felsch, Z. Kri.st., 

209: 517 (1994). 

2 S. Y. Zhang. 0. Talu. and D. T. Hayhrst, J. Ph~ls. Clcem., 95, 1722 (1991). 

1:< 1 X. Y. Lil~. \V. F1. Su, Y. F. \\kng, and X. D. Ztiao, .I. Chem. Soc.. Chrm. 

Commun., 902 (1992). 

60 

Zeolite Na A+NaCI 16 4kbar 

Figure 1. Diffraction Pattern of Ta--1 at 

1.68 GPa 

Figure 2. Lattice Constant vs. Pressure

Lattice Parameters and Phase Transitions in Lal-,Sr,MnOs 

(x=0.12,0.17) * 1 x7A 1 

T. Iglesias, D. E Cox, and G. Shirane (BNL), K. Hirota (Tohoku U.) 

High-resolution powder data were collected from polycrystalline samples of 

Lal-,Sr,Mn03 (x = 0.12 and 0.17) obtained by carefully crushing small single 

crystals grown by the floating zone technique. In the case of the 0.17 sample, a 

structural transition from a rhombohedrally-distorted perovskite- like phase (R-3c 

symmetry) to an orthorhombically-distorted phase (Pnma symmetry) was observed 

below -- 320 K. The transformation was about 90% complete at 285 K, but a small 

amount of residual rhombohedra1 phase persisted down to 210 K. Only small dis- 

continuities were observed in the lattice parameters and unit cell volumes. 

The behavior of the 0.12 sample was extremely complex, with two coexisting 

orthorhombic phases at 300 K, one of which transformed first to a monoclinic phase 

at -- 295 K, and then to a triclinic phase at % 140 K. 

In-situ Ion Exchange Using the Small Environmental Cell for Real 

Time Study: (SECRETS) 

Y. Lee and J.B. Parise (SUNY at Stony Brook) 

In-situ ion exchange experiments were performed on zeolite Na-Y(SRM2850) and 

clinoptilolite at the X7A beamline using the Small Environmental Cell for REal 

Time Study(SECRETS). A powdered sample of each material was placed in a 

0.7mm capillary while exchange solutions flowed through the SECRETS apparatus. 

Data were taken by scanning a PSD with a 3" window in steps of 3" and 

counting times of 20 sec per step. Treatment of zeolite Na-Y with 0.1M solution of 

CsN03 showed changes in the relative intensities in the subsequent diffraction patterns 

which are indicative that ion exchange has occurred and no change was noted 

after 30 minutes. Similar experiments were undertaken with clinoptilolite powder 

and Sr(N03)~ exchange solution. Detailed study of changes in relative intensities 

and cell parameters as a function of exchange level will reveal the kinetics of ion 

exchange for a particular exchange system. These studies are ongoing. 

20, degrees 

Figure 1. Three of the diffraction patterns taken in-situ while O.1M of CsN03 exchange 

solution flows through the SECRET cell. Changes in the relative intensities 

4d C1 

w 

* Work at BNL was Supported by the U.S. Dept. Of Energy, Division of Materials 

Sciences, under Contract No. DE-AC02-76CH0016 

of the peaks reveal ion exchange have occured and no more change is noted after 

30 minutes (wavelength=0.790012). 

X7A

C, 

3 

Location of CF3C1 in Partially-hydrated RIaximum Aluminum Na.K- 

X type Zeolites 

Y. Lee. J.B. Parise, and P. Norby (SUNY at Stony Brook) 

X7A 

Rietveld analysis using synchrotron x-ray powder diffraction data collected at 

15 K at the X7A beamline reveals that CFC-13 (CFsCl; chlorotrifluoromethane) 

sorbed on Na,K-LSX binds through fluorine to sodium ions around the single 6- 

ring aperture. There are approximately 33.5 molecules of CFC-13 per unit cell, 4.2 

per supercage or close to one CFC-13 molecule aronnd each single 6-ring window. 

Interactions between individual CFC-13 molecules and extrafrarnework Na atoms 

are typified by the interatomic distances; 2.49(2)Afor F(1)-Na(3), and 2.93(4)afor 

F(3)-Na(3). The Na(2) and K(2) sites, which are separated by 0.897(21)A, are 

not simultaneonsly occupied as in the case of K(1) antl Na(1) which is close to 

each other by 2.022(26)X, and have no interaction with the CF3Cl molecules. This 

study reveals some of the strnctnral details of the interactions of CFC-13 molecules 

with partially l~ydrated maximnm Na.K-X zeolite. Further studies of niaterials 

with different loatlirig levels of the ctiloroflnorocarbon, as a function of hydration 

level and with different exchangeable cations arc required to characterize changes 

as a filnction of basicity of thc zeolite fran~ework and Lewis acidity of the extra 

framework cation. These studies are ongoing. 

Figure 1. Graphic representation showing the refined position of CFC-13 molecules 

around the 6-ring window of the supercage. CFC-13 molecules and extraframe- 

work cations are represented as circles while Si and =\I tetrahedra constitute the 

framework. The carbon atoms have been omitted for clarity. 

I Low Temperature X-ray Diffraction Study of Laz-,-,Sr,Nd&uOe I X7A I 

A. R. Moodenbaugh, L. H. Lewis, D. E. Cox, and S. Soman (BNL) 

The relationship between superconducting transition temperature (T,) 

and the low temperature crystallographic phases in La2-,BaXCuOi~ and 

La2-,-,Sr,Nd,CuO~ has been studied for almost 10 years now. The occurrence of 

a low temperature tetragonal phase (LTT) is associated with a reduced T, near the 

x=0.12 composition. However, the relationship is still not completely understood. 

For example, in the Nd-free system Laz-,Sr,CuO.l the diffraction pattern exhibits 

the orthorhombic structure (LTOl) which is asssociated with better superconclucting 

properties. Yet T, is reduced near the x=0.12 composition. 

It is well established that this phase transitions (LTO1-LTT) is first order, and 

there is some temperature range over which the two phases coexist. \lTe undertook 

a high resolution x-ray diffraction study of some of these materials to carefnlly 

monitor the development of the LTT phase as temperature is rednced. IVe find 

that in samples which transform to LTT, the LTT phase may begin to form up to 

40 K above the acknowledged transformation temperature. 

At the composition Lal.~sSro.12Cu0.t we studied the 020,022 (LT0l)region as a 

function of temperature. At low temperatures a two peak fit to the data does not 

atlequately describe the diffraction. A broad thirtl diffraction peak betwcen the two 

major peaks improves the fit. This peak has a full width at half nlaxin~urr~ about 

three times that of the LTOl peak, arltl represents abo~it 10% of the total diffraction 

at this angle. 

\Vhile this thirtl peak is relatively broad compared with t,he LTOl peaks, its 

position antl breadth are consistent with typical LTT tliffract,ion pcak widths. (Thr 

broad peaks in LTT probably rcpreserlt an intrinsic ir~tiornogeneity that has been 

tloc~nnentcd using electron microscopy, both for ruicrostructnral ant1 diffract,ion 

studies.) In our opinion. this x-ra,v tlitfract,ion tlata snggests a partial trnrisfornlation 

of La~.~sSro.l-CuO.c to thc LTT phase.

td 

+ 

High Pressure-High Temperature Synthesis of a Novel Perovskite 

CaMnTizOs. 

J.-H. Park and J.B. Parise (CHiPR, SUNY at Stony Brook) 

X7A 

In the investigation of the CaTiO3-MnTiOs system, a new CaMnTiz06 perovskite 

compound isomorphous with the CaFeTizOs[l] was synthesized using a stoichiometric 

mixture of the CaTi03-perovskite and MnTi03-pyrophanite (JCPDS29- 

902). Polycrystalline and single crystal (10x10~20 pm3) CaMnTizO6 perovskite 

compound was prepared via high pressure-high temperature experiments under 

14.5-15 GPa and 1200°C. Synchrotron powder X-ray diffraction data were collected 

using PSD[2] at the X7A beamline, NSLS. From the extinction conditions the unique 

space group P4~/nmc is found with cell parameters a=7.5339(5) and c=7.6027(6) 

A. The structure was refined using CaFeTizO~[l] as a starting model (Fig. 1). 

There are two Mn sites, (1) the one in a tetrahedral site and (2) the other in square 

planar configuration. Mn(2) prefers sites out of the plane along the [OOl] axis. 

[I] K.Linenweber et al, J. Solid State Chem., 114, 277 (1994). [2] D. E. Cox et al., 

Aust. J. Phys., 41, 117 (1988); D. E. Cox, High resolution powder diffraction and 

structure determination, in Synchrotron Radiation Crystallography ed. P. Coppens, 

Academic Press: London (1992); G.C.Smith, Syn. Rad. News, 4, 24 (1991). 

Figure 1. Projection of the structure of CaMnTizO6 along [loo]. The TiO~units 

and Ca/Mn ions are represented by the octahedra and smallllarge circles. 

Ab Initio Crystal Structure Solutions of Metal Phosphonatcs from 

Synchrotron Powder X-Ray Data I x7A I 

D.M. Poojary, D. Grohol, F. Gingl, and A. Clearfield (Texas A&M University) 

In the September 1996 to present time span we have obtained three data sets 

at the X7A beamline of the National Synchroton Light Source. One of the data 

sets involved a drug that exists as two isomers. One is inactive and the other 

physiologically active. The initial data sets were obtained in house on our rotating 

anode unit and solved but the active isomer resisted complete solution. 

The problem was solved with the Synchrotron data . The active isomer has an 

open structure whereas in the inactive isomer the phenyl rings close in on the 

active site probably causing steric hinderence. We were not able to publish this 

study as the sponsor wants to maintain the information private. A second structure, 

ZrzP04(03PCH~CHz(Viologen)CHzCH~P03)X3, was solved entirely from 

synchrotron data. It has a complex porous structure, is photoactive and behaves as 

an anion exchanger, X- being the exchangable ion [Chem. Mater. 8, 2243 (1996)l. 

The most recent data set is for U2(03PCH3)2. This compound luminesces whereas 

UOz(03PCHzCL)z does not. The quenching process and luminescence properties 

are under study. The structure solution is in progress.

A 

p3 I Certification of Zeolite Standard Reference RIaterials I X ~ A 

I 

B.H. Toby and N. Khosrovani (NIST) 

A group of industrial and academic researchers presented a proposal to NIST 

requesting that NIST certify and release a series of zeolite reference materials. The 

result was a decision to obtain three zeolite materials from industrial sources, Na- 

FAU (Y), Na-LTA and hIFI to be certified as SRhIs 2850, 2851 and 2852, respec- 

tively. Approximately eight additional zeolite materials will be released without 

certification as reference materials. 

Synchrotron diffraction was selected as one of the principal methods for character- 

izing these materials with respect to the presence of impurity phases lattice param- 

eters and sample-tc-sample variations. Since most zeolites absorb large amounts of 

water and their water loadings change depending on the water partial pressure, care 

was taken to see that every samplc mas exposed to a uniform humidity level prior 

to sealing the sample into a capillary tube. Despite these precautions. larger than 

expected variations were seen in the obsewretl lattice constants. It is not known 

if these variations are due to the samples being inhomogeneous or due to nlinor 

changes in water loading. Further work is planned to see if this can be determined. 

1 sit in^ of the Structure Directing Agent in Zeolite CIT-1 I X ~ A 

I - - - 

B.H. Toby, N. Khosrovani (NIST) and M. Davis (Caltech) 

1 

I I 

The zeolite CIT-1 was chosen for study because it can be synthesized nearly 

free of stacking faults using a particular structnre directing agent (template) while 

similar organic molecules prodnce a related zeolite. but with up to 30% stacking 

faults. Crystallography combined with molecular mechanics are being used to study 

the interaction of the template with the zeolite. Synchrotron and neutron data were 

collected on samples of CIT-1, as synthesized (with template present) and calcined 

(without template) using the NIST BT-1 nentron powder diffracto~neter and the 

NSLS X7A x-ray powder cliffractometer. For the neutron work, two materials were 

used, one where the amine methyl groups were denterated and one non-denteratetl. 

hIolecular modeling demonstrated three possible ways that the template can be 

accorriotlatccl in the CIT-1 pores. However. a combined Rietveltl refine~rlent of the 

neutron and synchrotron datasets clemonstratccl that only two of these orientations 

actually occur. The template molccl~lcs pack very snugly into thc pore volnme of 

the zeolite. \ire are currently investigating the ericrgctics of this packing.

I Direct Evidence of Charge Disproportionation in CaFeOs * I X ~ I A I Low Temperature Phase Transitions in Nd0.5Sr0.5Mn03 * I X ~ I A 

P.M. Woodward (BNL) 

P.M. Woodward, T. Vogt, D.E. Cox (BNL), C.N.R. Rao (Indian Institute of Sci- 

Mossbauer studies of stoichiometric CaFeO3 show the presence of a single line at ence) and A.K. Cheetham (UCSB) 

300K which evolves into two magnetic hyperfine patterns of nearly equal intensity 

at 4K [I]. This has been interpreted as being due to 2J?e4+ + ~ e + ~ ~ + e charge ~ + 

disproportionation. However, attempts to obtain direct crystallographic evidence of 

this charge disproportionation have not previously been successful. Observation of 

the charge disproportionation is difficult because the phase transformation involves 

only small shifts of the oxygen ions. Therefore, in an X-ray diffraction pattern 

the superstructure peaks are very weak. Neutron diffraction is more sensitive to 

the oxygen shifts, but interpretation is complicated by the presence of magnetic 

reflections. 

Powder X-ray diffraction data was collected at 300K and 15K on a sample of 

CaFe03 synthesized under high oxygen pressure. The structure was refined at 

both temperatures using the Rietveld technique. At 300K the sample has the 

GdFe03 structure, space group Pnma and lattice constants a=5.3445A, b=7.5292& 

c=5.3193A. The Fe-0 distances are 4x1.919(5)A and 2x1.930(2)A. At 15K weak superstructure 

reflections (the strongest superstructure reflection (110) has an intensity 

of 0.03% of the strongest peak (121) in the pattern) appear which are consistent 

with a rock salt ordering of Fe3+/J?e5+. The space group is P21/n and the lattice 

constants are a=5.3100A, b=5.3470& c=7.5185A, /3=90.058". The Fe-0 bond 

distances are 2x1.872(8)& 2x1.894(9)& 2x1.88(l)A for Fe(l), and 2x1.962(8)A, 

2x1.975(9)& 2x1.96(1)A for Fe(2). 

[I] M. Takano, et al. Muter. Res. Bull. 12, 923-928 (1977). 

At room temperature Nd0.5Sr0.5Mn03 is reported to be a paramagnetic insulator 

[I]. Upon cooling single crystals transform into a ferromagnetic metallic state near 

250K, and then abruptly transform into an antiferromagnetic insulating state near 

160K [1,3]. It is believed that the 250K transition is a consequence of double 

exchange interactions, while the 160K transition is driven by charge-ordering of 

~ n ~ + / [I]. ~ n Neutron ~ + diffraction studies have shown the low temperature phase 

to have the CE-type antiferromagnetic structure, but no refinement of the crystal 

structure at low temperature has been carried out to confirm the presence of chargeordering 

[3]. 

We have collected powder X-ray (beamline X7A at NSLS) and neutron (beamline 

BT1 at NIST) powder diffraction patterns on a ceramic sample of Ndo.5Sr0.5Mn03, 

over the temperature range 15-300K. At room temperature the sample is single 

phase (HTO phase), space group Imma (a=5.4245& b=7.6226A, c=5.4682A) and 

Glazer tilt system aOb-b-. This structure is in good agreement with earlier results 

PI. A s the sample is cooled a second phase appears between 225K and 200K 

LTOl phase), and a third phase near 150K (LT02 phase). The LTOl phase shows 

a contraction in b and an expansion in both a and c (a=5.4413A, b=7.5262A, 

c=5.4946& at 160K), with respect to the room temperature structure. This is 

thought to be a result of "orbital ordering" of the filled Mn 3d,z orbitals. The 

LT02 phase has unit cell constants very similar to the LTOl phase, but several 

superstructure reflections are present which can only be indexed by doubling the a 

axis (a=10.8776& b=7.5134A, c=5.5069& at 15K). Combined Rietveld refinements 

of both the X-ray and neutron patterns (using breathing rigid body constraints) at 

15K give Mn-0 bond distances in the LT02 phase (space group P21/m) which 

directly show ~ n ~ + / charge-ordering. ~ n ~ + Refinements of the neutron data show 

that the HTO phase is ferromagnetic below 250K, the LTOl phase has an A-type 

antiferromagnetic structure, and the LT02 phase has a CE-type antiferromagnetic 

structure. There is no indication of charge-ordering in the LTOl phase. 

I 

1 

I 

Kuwahara, et al., Science 270, 173-177 (1996). 

2 Caignaert et al., Solid State Commun. 99, 961-963 (1995). 

3 Kawano et al., Phys. Rev. Lett. 78, 4253-4256 (1997). 

* This work was supported by the Division of Materials Sciences, U.S. Department of * This work was supported by the Division of Materials Sciences, U.S. Department of 

Q, 

QJ Energy, under contract No. DE-AC02-76CH00016. Energy, under contract No. DE-AC02-76CH00016.

tj 

a 

rp The Influence of Cation Size on the Structural Features of 

Structural Analyses of Stuffed Quartz Phases Along the LiA1Si04- 

Lno,5Ao.silInOs Perovskites at Room Temperature 

X7A 

SiO? Join 

X7A 

* 

P.hI. TTioodward. T. Vogt, D.E. Cox (BNL), C.N.R. Rao (Indian Institute of Sci- 

ence) and A.K. Cheetham (UCSB) 

Structure determinations have been carried out on samples of Nd1/2Sr1/2fiIn03, 

Sml12Srl12Mn03, Gdl12Srl12Mn03, Ndl/2Cal/2!2.1n03, Gcll12Cal12MnO~, 

Lal/4Ndl/,LSrl121\.lnOy. and Y1/2Cal/2AIn03 at room temperature using high resolution 

synchrotron (beamline X7A at NSLS) ancl neutron (beamline BT1 at NIST) 

powder diffraction. The average hln-0-hIn bond angles decrease as the average 

ionic radii of the Ln/A cations, , decreases. This decrease is more rapid when 

A=Sr than when A=Ca. The average Mn-0 distance increases steadily as 

decreases, indicating a rccluction in the overall hln-0 bonding. Both findings are in 

contradiction to common assumptions made in the literature; that the XIn-0-hIn 

bond angles are dependent solely on the ionic radii of the Ln/A cations, and that 

the hln-0 bond distances are independent of the Ln/A cations. Both bond distance 

ancl bond angle trends lead to a decrease in the width of the o* and T* bands as 

tlecreases, destabilizing the ferromagnetic metallic state. 

Individual hIn-0 bond distances show the onset of a cooperative Jahn-Teller 

distortion (formation of a large polaron) for valnes below 1.19X. This effect is 

mirrored in the behavior of the lattice constants as tlecreases. Quantifying the 

octahedral tilt angles suggests an a- b+ap --t a boa- + a a a evolution of the tilt 

systern in the LI~~/~S~~/~."L~~LOR 

seriw as < r~> increases. Relationships between 

the octahedral tilt nnlges, the cooperative .Jahn-Teller distortion and the lattice 

constants were also cxarninetl. It wxs ffo~nd that in tht: Pnrna setting (tilt systern 

apb+a) the c lattice constant was very sensitjive to octal~etlral tilting, decreasing 

rapidly as the tilt angles increase, but relatively insensitive to the cooperative .Tatin- 

Teller disortion. Tht: other two lattice constants were fo~~ntl to be much lcss sensitive 

to the octahedral tilting distortion, bnt strongly depenrtent upon the .Tahri-Teller 

distortion, with a increasing antl h decreasing as thr magnitntle of the .Tahri-Teller 

tlistortion increxsctl. 

This work was supported by the Division of 1Iaterials Sciences. U.S. Department of 

Eners. under contract So. DE-.\C02-76CH00016. 

H. Xu: P.J. Heaney, D.hI. Yates (Princeton U.). J. Liu (SUNYat Stony Brook), A. 

Navrotsky (Princeton U.) and R.C. Liebermann (SUNY at Stony Brook) 

Stuffed quartz phases along the LiAlSi04-Si02 join are structural derivatives of 

quartz, in which tetrahedral Si4+ cations are replaced by Al"' and the charge is 

balanced by the incorporation of Li+ into the main channels of the structure [I]. 

This group of compounds is of considerable interest because of their superionic 

conductivity and near-zero thermal expansion [2.3]. 

TVe have investigated the phases with the compositions Lil-rAl~-xSil+xO~. x 

= 0, 0.2, 0.33, 0.5 0.7, 0.9, by synchrotron powder X-ray diffraction with a linear 

position-sensitive detector. Rietveld analysis of unit cell parameters reveals two 

trend changes in a or c as a function of composition(x): TVith increasing silica 

content, a first remains approximately nnchangecl up to -0.3 and then tlecreases 

with a slope change at -0.8. In contrast, the cell parameter c first exhibits a linear 

decrease between x = 0 and -0.3, remains roughly constant between x = -0.3 antl 

-0.8, antl decreases between x = -0.8 and 1.0. Lattice changes at -0.3 may be 

related to an AI/Si order-tlisorcter transition. hlore specifically, the end member 

O-e~~cryptite hay a completely ortlered M/Si configuration, but as Si substitution 

for Li+AI increases, this order is gratldly lost and disappears at -0.3. The slope 

change at -0.8 probably results from a phase trar~sition that is analogo~~s to the a-3 

q~~artz transformation. In other words, for those silica-rich compositions, since there 

is not sufficient lithium to prop open the N-qnartz structure, the ;tlnn~inosilicate 

frnrnework tends to collapse to the denser ru-qnartz rnotlification. As the changes 

in a arid c around 4.3 cancel each other, there is no tlisconti~luity present in the 

plot of cell-volnrne V vs. x up to x = -0.8, implying a continuous natnre of the 

order-disorder transition. However, t h tlisplacive ~ transition at -0.8 is evident in 

the V-x plot due to the different densities of the a- aritl 6-quartz frameworks. 

[I] Buerger. LI..J. (1954) Am. AIin., :39, 600-614. [2] Nagel, TV. antl Bohm. H. 

(1982) Sol. State Comrn~~r~., 42, 625-631. [R] Beall, G.H. (1994) in Hcar~ey. Prewitt 

aritl Gihbs (ed.). Reviews in LIineralo~, 29, LISA, TVashington D.C.. 469-505.

Fd 

a 

Time Resolved In-Situ Diffraction Studies of Intercalation Processes: 

Intercalation of 1,6-Hexanediamine in a-Zr(HP04)2,H20. * I x7B I 

A. M. Krogh Andersen, E. Krogh Andersen, I. G. Krogh Andersen (Odense U., 

Denmark), P. Norby (SUNY at Stony Brook) and J. C. Hanson (BNL - Chemistry). 

Casciola et al.' showed by batch titration that there exist three intercalates of 

1,6-Hexanediamine (HeDA) in a-Zr(HP04)z'HzO (a-ZrP), and they determined 

their composition. We report a continuation of studies of intercalation processes. 

The experiment was performed at 10' using an INEL CP120 detector. The sample 

was in a 0.5 mm quartz capillary. In the bottom of the capillary was a plug of 

quartz wool, then a loose plug of a-ZrP and another plug of quartz wool. A small 

amount of 10.85 m aqueous solution of HeDA was deposited 1-2 mm from the latter 

quartz plug. Diffractograms were recorded at 1 minute intervals. The intercalation 

process was started by pressing (4 Atm.) the solution into contact with the a-ZrP. 

Figure 1 shows a small part of the diffractoarams - as a 3-D representation. time on 

the z-axis. The peaks are (from the left): 

a'l 002 reflection of a-ZrPHeDA.Ho0 bl 002 reflection of a-ZrP'0.5HeDA'1.5H?O 

c) 002 reflection of ~-z~P.o.~H~DA.

0, 

C, 

Temperature Resolved Diffraction: Lattice Constants and Phase 

Changes in Lanthanum Manganate 

E. Krogh Andersen, I. G. Krogh Andersen (U. Odense. Denmark), P. Norby (SUNY 

at Stony Brook) and J. C. Hanson (BNL) 

A 0.5 mm quartz capillary with a small amount of LaMn0s.00 (prepared according 

to reference 1) was evacuated. sealed and heated from 25 to 900" during 4 hours 

and cooled again. Data were collected at beamline X7B using the position sensitive 

detector INEL CPS120. The wavelength was 1.1143 A and the 20 range covered 

was 2-120". The observed phase transitions orthorhombic - cubic - hexagonal are 

pictured in Figure 1 and Figure 2. Figure 1 shows the unit cell parameters versus 

temperature. Figure 2 shows the unit cell volumes during heating. The unit 

cell volumes are calculated using the program CELLKANT?. In order to compare 

the unit cells for the different phases the unit cell axes were transformed into 

pseudocubic axes. Similar experiments were performed with Lito.g~Sro.o~hIriO:~.oo, 

Lao.~sSro.oshInO:~.oo. Lao.90 Sr0.10hIn03.00 and Lao.~sSro. 1s hln03,oo. These data 

have not yet been processed. 

I. G. Krogh Aridcrsen, E. Krogh Andersen, P. Norby and E. Skou, J. Solid State 

Ckm. 113. 1994, 320. 

N. 0. Ersson: Program. CELLKANT, Institute of Chemistry, Uppsala Univer- 

sity. Sweden. 1981. 

Tnrnnnrnt~~ml'~\ 

Figure 2. Normalized unit cell vol- 

Figure 1. Xormalized unit cell parameume 

versus temperature. Circles: orthorhombic 

form. Triangles: cubic form. 

ters versus temperature. Squares: hexagonal form. 

X7B A Time-resolved X-ray Powder Diffraction Study of Phase Transfor- 

mations in the Quinuclidine-Ah-Ge-S System 1 1 

C.L Cahill, Y. Ko? J.B. Parise (SUNY at Stony Brook) 

Benchtop syntheses in the quinuclidine-Mn-Ge-S system have yielded mixed 

phase products, both as a function of aging time and uptake of transition metal. A 

real time x-ray diffraction study was carried out to determine the synthetic pathway 

for the formation of these open framework materials. 

A slurry of starting materials to produce Qni-AlnGeS-1 (established nomenclature 

for synthetic framework materials: organic guest-framework elements-structure type 

number) was loaclecl into a glass capillary. The sample was heated to 180C over 90 

minutes via an air heater. while hydrothermal conditions were maintained through 

an over pressure of Nz(g). Real time x-ray diffraction spectra were collected on 

the X7B Translating Imaging Plate System (TIPS), antl the resulting time resolved 

plot is shown below. The amorphous starting slurry crystallizes to Qui-GeS-10 

at approximately IOOC. The structure of this material was previo~~sly tleterrninecl 

antl was known to contain no transition metal. At approxirnatcly 150C, the type 

10 struct~n-e proceeds throngh an amorphous region before re-crystallizing as Qui- 

AInGeS-I. The type I structnre was known previously as well, antl contains a 

transition metal species in its framework. Thns a structural rearrangement driven 

the uptake of a transition metal has been observed. 

2 

Figure 1. 

2 Theta

I in situ X-ray Powder Diffraction Study of the Synthesis of DEA-Ins- I , I AlJS 

I SB1 and DEA-I~S-SB~ 

C.L. Cahill, Y. KO and J.B. Parise (SUNY at Stony Brook) 

Single crystal x-ray structural analysis of materials in the diethylamine-In-S sys- 

tem [DEA-Ins-SBl and DEA-Ins-SB2: (established nomenclature for synthetic 

framework materials: organic guest-framework elements-structure type number)] 

have been carried out previously. Their modes of formation or synthetic pathways 

however, have remained unclear. For example, reaction products in this system of- 

ten contain mixed phases or vary as a function of aging time; octahedral and plate 

crystals were obtained depending on how long the reactants aged. A time resolved 

x-ray diffraction study was carried out in order to elucidate these problems. Ele- 

mental indium and elemental sulfur were loaded into a 0.7mm quartz capillary. The 

solids were then covered with a volume of diethylamine. The sample was heated to 

250C over 180 minutes via an air heater, while hydrothermal conditions were main- 

tained through an over pressure of Nz(g). Real time x-ray diffraction spectra were 

collected on the X7B Translating Imaging Plate System (TIPS), and the resulting 

time resolved plot is shown below. Powder diffraction spectra were calculated from 

the known crystal structures of DEA-Ins-SBl (3-D open framework) and DEA-InS- 

SB2 (2-D layered structure). From these, it was determined that the 3-dimensional 

structure forms first, and the rearranges to form the 2-dimensional structure. 

I A Small Environmental Cell for Real Time Studies (SECReTS) I X ~B I 

C.L. Cahill, P. Norby, C. Koleda, J.B. Parise (SUNY at Stony Brook) 

We describe here the development of a micro-reaction cell for in- situ powder 

diffraction studies which can be used for hydrothermal titration, ion exchange, hy- 

drothermal precipitation reactions and to investigate solid/gas phase interactions 

in real time. The design of the reaction cell is shown in figure 1. Reactions take 

place in a 1 mm quartz glass capillary (A) which is mounted in a Swagelock tee (B) 

using a Vespel ferrule. Through the connected tube (C), a pressure can be applied 

to the surface of the reaction mixture in the capillary. Injection takes place through 

a 0.3 mm quartz glass capillary (D), which goes through the tee and into the 1 mm 

capillary. This 0.3 mm capillary is mounted between a Swagelock elbow and the tee 

with Vespel ferrules, all of which are mounted on a modified goniometer head (F). 

Injection under pressure through the elbow (E) is possible via a gas chromatogra- 

phy syringe (not shown) mounted in an aluminum holder. A screw connected to 

the piston of the syringe ensures pressurization. By turning the screw, the piston is 

depressed and a controlled volume can be injected into the 1 mm capillary through 

the 0.3 mm capillary. Alternatively, the position of the sample capillary (A) can 

be plugged, and the assembly extended to expose the injection capillary location to 

the X-ray beam. Ports (G) and (C) then become supply and exhaust lines respec- 

tively for flow-through ion-exchange experiments or solid/gas phase reactions. As 

a demonstration experiment the precipitation of Bas04 was studied using the mi- 

cro reaction injection cell. The experiment was performed at the Chemistry beam 

line X7B. Time resolved powder diffraction data were collected (X=1.284) using 

the Translating Imaging Plate (TIP) camera . The syringe and connecting tube 

were filled with a saturated NazS04 solution, and a 0.3mm capillary was mounted 

between the inner and outer fitting extending approximately 20 mm out from the 

outer tee. The Swagelock elbow and the capillary were filled with the NazS04 so- 

lution, and the syringe pulled back so that a 2 mm air bubble was formed at the 

end of the capillary. This prevented contact between the two solutions prior to the 

injection. A 1 mm capillary was filled with a saturated BaC12 solution, and was 

mounted in the outer ferrule. The cell was mounted on the diffractometer so that 

the X-ray beam was hitting the end of the small capillary, and an oscillation of 

approximately 45 was used to ensure randomization of the crystallites in the beam. 

Figure 1. Figure 1.

0 

Reaction Kinetics of the Crystallization of NnAPO-5(AFI) and 

ZnAPO-47 (CHA) " 

X7B 

A. Noerlund Christensen (Aarhus U.), T. R. Jensen (U. of Odense), P. Norby 

(SUNY at Stony Brook), J. Hanson (BNL) 

Synchrotron X-ray powder diffraction was used for in-situ studies of the crystallization 

of microporous aluminophosphates ancl of Me-substituted aluminophosphates. 

The reaction mixtures for the crystallization experiments were gels containing 

one of the templates. 2-diethylarninoethanol, di-n-propylamine. triethylamine 

or tripropvlamine. The identified reaction products were, AlPO't (tridvmite 

type), APO-5 (AFI), APO-11 (AEL), hIgAPO-5 (AFI). hInAPO-5 (AFI), c~,

Cation Migration in Zeolites: An In Situ Powder Diffraction and MAS 

NMR Study of the Structure of Zeolite Cs(Na)Y During Dehydration 

* 

X7B 

C. P. Grey, P. Norby, F. I. Poshni (SUNY at Stony Brook), A. F. Gualtieri (Modena 

IT), J. Hanson (BNL) 

A knowledge of the positions of the extra-framework cations is fundamental to the 

understanding of the adsorption and catalytic properties of cation-exchanged zeolites. 

This is particularly important in the case of zeolites where only partial cation 

exchange is possible. We have used in-situ synchrotron X-ray powder diffraction 

and 133Cs MAS NMR to investigate the cation migration and ordering in samples 

of cesium exchanged zeolite Nay, as a function of temperature, cesium cation 

exchange level, and during dehydration.1 Figure 1 shows the diffraction pattern 

collected from a sample of Na 18C~38Si13&~~0~~4 while ramping the temperature 

(under vacuum) from 90 - 500 "C over 5 hours. The temperature was then held 

at 500°C for a further 3 hours. Significant changes are initially observed as water 

is removed; further changes are seen above 300 "C ( 250 min.) which are predominantly 

a consequence of the cesium-ion migrations. Rietveld refinement of these 

time-resolved diffraction patterns was performed, and revealed the temperatures 

at which the different cation migrations occur. Initially (above 180 "C), sodium 

cations in the site I' positions in the sodalite cages migrate into the double six 

rings. This is followed by a migration of the cesium cations, originally only present 

in the supercages, into the sodalite cages. Migration of sodalite cage sodium cations 

to the supercages occurs above 300 OC. 

Cation positions in both the partially dehydrated and dehydrated material were 

also observed to be highly sensitive to temperature: at high temperatures, equal 

numbers of cesium cations were found in the site 111' and site I1 positions in the 

supercages, while at temperatures close to room temperature, the cesium cations 

are almost all ordered on site 11. 

Thus in conclusion, partially exchanged CsY, dehydrated above 300°C, will contain 

sodium cations in the supercage sites which are, therefore, accessible for gas 

binding. In addition, the occupancies of the different supercage sites are highly 

temperature dependent, and the room temperature structure cannot necessarily be 

assumed to be an accurate model for the high temperature structure. 

1. P. Norby, F.I. Poshni, A.F. Gualtieri, J.C. Hanson, and C.P. Grey, submitted 

to J. Phys. Chem. 

Figure 1. The X-ray powder pattern of Cs(Na)Y during dehydration. 

I 

rn 

a * Support from the NSF through an intra-agency transfer to the US DOE BES. 

In situ XRPD Study of the Crystallization of Zeolites from Natural 

Halloysite * I x7B I 

A.F. Gualtieri (U. of Modena, Italy), P. Norby (SUNY at Stony Brook), and J.C. 

Hanson (BNL) 

In our previous work at X7B the mechanism of hydrothermal synthesis of zeolite 

NaA and hydroxysodalite in solution has been investigated (Gualtieri et al., 

1997a,b). The precursors utilized for the synthesis experiments were an orderered 

and a disordered kaolinites activated at 600°C and 800°C, respectively. The results 

indicate an autocatalytic mechanism for the crystallization of both zeolites 

species, and dependence upon the thermal history and not upon the degree of 

disorder (the reaction is much faster from metakaolinite, the precursor activated 

at 600°C). Since zeolites formed from kaolinite have the same Si:Al ratio (1:l) of 

the precursor, we are interested in the study of the crystallization process using a 

precursor with a different Si:Al ratio. A natural halloysite [Alz(OH)4Si2O~nH20] 

interdispersed in an amorphous silica matrix has been selected. The Si:Al ratio 

is 4. The sample was activated at 600°C for 5 h and the syntheses were carried 

out in isothermal mode in the range 70-150°C using a 4M NaOH solution with 

s:1=1:5. Preliminary data shows that three different zeolites are formed: NaX 

[Na88A188Si104038416H2200] crystallizes first at lower isothermal T and for shorter 

times, and is progressively replaced by Nap [Na7A17Si903217H20] which in turn 

is replaced by analcime [Nal6A116Si3209616H20] at higher isothermal T and for 

longer times. The Ostwald's rule is perfectly fulfilled. It is interesting to note that 

the Si:Al ratio is progressively changing in the forming zeolite as a function of T 

(from 1.2 in NaX to 1.3 in Nap and finally to 2 in analcime). The analysis of the 

data is still in progress. 

Gualtieri A,, Norby P., Artioli G., Hanson J. (1997a) Phys. Chem. Mynerals 

24:191-199. 

Gualtieri A., Norby P., Artioli G., Hanson J. (1997b) Microporous Materials 

9:189-201. 

* DOE BES Contract DE-AC02-76CH00016

-J 

o 

Preliminary X-ray Reflectivity Study of Interdiffusion in Quantum 

X7B 

Well Structures 

S. A. Holt, A.S. Brown (Australian National U.) and D.C. Creagh (U. of Canberra) 

The properties of quantum well (QW) devices structures, e.g. lasing wavelength, 

are strongly dependant upon the interface properties of the structure. This work is 

at the beginning of a project using x-ray reflectivity to study the interface structure 

of QW devices. To this end we have performed x-ray reflectivity (XRR) on model 

structures to study the effects of inderdiffusion on the interface structure, in addition 

me are also studying the diffusion of defects introduced by anodic oxidation of the 

capping layer. 

Data analysis and modelling are still in progress, however a small subset of the 

results obtained is shown below. Figure 1 shows the XRR profile from an asproclucetl 

sample compared with that from the anodically oxidised equivalent. It is 

apparent that the structure of the capping layer is quite different as the fine fringe 

period (due to the total device thickness) has been radically altered. The long period 

(buried barrier layer) though has remained lmchangetl by the surface treatn~erit. 

Rapid thermal annealing at 9OO0C completely destroyed the fringe structure in 

comparable samples. In order to highlight different aspects of the sample structure 

we also rrcortletl XRR profiles closc to ant1 far from the gallium edge (1.198 and 

0.9991 ;\ respectively). The effect of this "contrast variation" on the reflectivity 

profile of the oxitliscd sample can be seen in Figure 2. As expected the fringe 

periods are unaffected but the fringe amplitude (related to the scattering length 

density difference between the 1;tycrs) hits been motlitietl. At the longer wavelength 

the rffcctivc number of clectror~s of the gallium is retlucetl, errharlcirlg the contrast 

of the gallium rich barrier layer. 

Figure 1. Reflectivity of as-produced 

and osidisecl sample. llasimum Q, = 

0.35 -I-'. 

Figure 2. Reflectivity of oxidised sam- 

ple at two wavelengths. Maximum Q, = 

0.3.5 -4-I. 

The Low Temperature Struct~wes of Tls(AlSiO4)6 and Ag6(AlSi04)6 X7B 

from Image Plate Powder Diffraction Data 1 I 

B. B. Iversen, S. Latturner. C. Brown, N. Blake, G.D. Stucky (U. of California at 

Santa Barbara) and P. Norby and J. Hanson (BNL) 

Aluminosilicate sodalites of the general composition b16+,(AlSi04)6(X),7Hz0 

form model compounds for more complicated zeolite structures. They consist of 

space filling polyhedra (beta-cages). formed by a network of alternating, cornersharing 

Si04 and A104 tetrahedra [I]. The hI+ ions, which compensate for the 

negative charge of the framework, are located inside the beta-cages together with 

possible anions and neutral water molecules. The ions serve as spacers preventing 

the open framework from collapsing. Depending on the exact nature of the cage 

filling ions antl water molecules, the framework can acljust itself in the form of a unit 

cell reduction, a so-called "partial collapse" 121. llTe report here low temperature 

structures of two dry sodalites. TlG(AlSi04)~ antl Agc(A1SiO'l)c. based on synchrotron 

radiation powder diffraction data. In both structures statistical disorder 

of the six metal atoms clistributed over 8 cubic positions creates a pseudo-cubic 

structure. The data were collected on 200x400 mm Fuji IP's which were scarmetl 

off-line using a BAS2000 scanner. Detailed cfescription of the experimental setup 

at beam line X7B for IP powder diffraction measurcrncnts were reported by Norby 

[3]. In Figure 1 experimental details are shown arid iri Figure 2 preliminary structural 

results are given. Some rrservation remain about the results for Tlo(A1SiO.l)~ 

even though the refinement rrsitluals are very low. For this structure considerable 

changes in Si-0 antl Al-0 bond Icngtlis are observctl. which are very unusual for 

zeolitrs. This could possibly he due to a spacegroup error, antl work is in progress 

to clarify this aspect. 

[I] G. Engelhnrtlt, .T. felsche. P. Sicger. ,J. Am. Chem. Soc., 1902, 114, 1173-1182 

[2] [V. Depmcicr, Acta Ch-ystallogr. Scct B, 1984, 40, 185-191 [3] P. Norby. .J. Appl. 

Crystallogr., 1997, 30, 21-30 

Table 2. Bond lengths and angles. 

TlJAISiOJ Ag,[AISiO.l 6 

Figure 1. Crystallogaphic data and ex- 

perimerrtal details Figure 2. Bond lengths and angles

2 

The Structure and Dynamics of Sodium Sodalite as a Function of 

Temperature 

X7B 

B. B. Iversen, S. Latturner, C. Brown, N. Blake, G. D. Stucky (U. of California @ 

Santa Barbara), P. Norby, and J. Hanson (BNL) 

The high temperature structure (T=675K) of dry sodium sodalite, Nae[A1Si04Is, 

was reported previously by Felsche et a1 [l] based on conventional powder diffraction 

data. In the high T phase statistical disorder of the six metal atoms distributed over 

8 cubic positions create a pseudo-cubic structure with spacegroup P-43n. However 

as the temperature is lowered an ordering of the sodium atoms takes place leading to 

one or more phase transitions. In order to solve this challenging structural problem 

we have measured temperature resolved powder diffraction data in the range 100 

- 650 K. As can be seen from Figure 1 the structural changes are complex and 

the spectra contain many subtle features. The cubic peaks move to higher theta 

values in the low temperature regime indicating a contraction of the framework 

with decreasing temperature. Furthermore, numerous well resolved superstructure 

peaks are present in the low T spectra. Work is in progress to establish the correct 

spacegroup for the low temperature phase and carry out Rietveld refinements as a 

function of temperature. This will provide detailed information about the dynamics 

of metals atoms suspended in a zeolite cage. To assist in the interpretation of the 

results and to gain insight into the catalytic behaviour of metal atoms in zeolites, 

ab-initio quantum mechanical calculations are also being carried out on the system 

1Q1 

1 J. Felsche, S. Luger, C. Baerlocher, Zeolites, 1986, 6, 367-372. 

lL1 t 2 1 N. Blake, V. I. Srdanov, G. D. Stucky, H. Metiu, J. Phys. Chem., 1995, 99, 

2127-2133. 

6 8 10 12 14 

Figure 1. Temperature resolved diffrac- 

tion pattern of Nas[AlSiO4]e in the low 

order region. The x-axes depict 2theta 

and the y-axes the uncalibrated temper- 4 7 48 49 50 5 1 

ature starting at 298 K going to 650 K 

and returning to 298 K. The tempera- Figure 2. Temperature resolved diffrac- 

ture scale is non-linear because of a wait- tion pattern of Nae[AlSi04]6 in the high 

ing period at the turning point. order region. Axes as in Fig. 1. 

Structural Origin of the Remarkable Mechanical Properties of Prunus 

X7B 

Serrula Bark 

B. B. Iversen, C. Zaremba, X. Xu, F. Wudl, G. D. Stucky, (U. of California) 

The bark of Prunus serrula is a natural composite plastic film with remarkable 

anisotropic mechanical properties. The bark is as strong as Mylar [poly(ethyleneterephthalate)] 

and as tough as one of the strongest man-made films, Kapton 

[poly 4,4'-diaminophenyl ether pyromellitamide)]. In a recent communication Xu 

et a1 1 1 reported detailed mechanical measurements characterising its properties. 

With the hope of gaining insight into the structural origin of the remarkable mechanical 

properties we have carried out low temperature (lOO(5)K) fiber diffraction 

measurements using the X7B image plate setup. The bark has a low crystallinity, 

which however can be increased by either stretching and heating the bark or by 

chemical treatment, see Figure 1. In the treated film not only does the intensity 

of the inner ring concentrate into fairly discrete peaks, but also a strong new peak 

appears at a lower d-spacing. In the high order region of the diffraction patterns 

weaker peaks appear with significant intensity, which are not observable in the 

untreated sample. Such details were not revealed in diffraction measurements using 

conventional X-rays and a Siemens SMART ccd detector. We are currently 

analysing the synchrotron patterns with the CCPl3 fiber diffraction software [2]. 

From SEM photos it is clear that the bark consists of lOxlOxlOO micron rectangular 

cells packed with their long dimension along the mechanically strong direction of 

the film. The diffraction patterns reveal that the fiber axis of the system is perpendicular 

to this direction. It is hoped that the patterns will allow us to establish 

which forms of cellulose are present in the bark. This may provide an explanation 

for the unusual properties of this material. 

1 X. Xu, E. Schneider, A. T. Chien, F. Wudl, Chem Mat, 1997, submitted 

I1 2 CCP13 Fiber Diffraction Programs, CCLRC Daresbury Laboratory, Keckwick 

Lane, Daresbury, Warrington, WA4 4AD, UK 

Figure 1. Diffraction patterns of an Figure 2. Diffraction patterns of a 

untreated sample of Prunus serrula heated and chemically treated sample of 

bark.Only the high intensity low order Prunus serrula bark. Only the high in- 

region is shown. tensity low order region is shown.

?d 

-J 

t~ 

In-situ Studies of Ethylene Sorption in CuA1C14 * 

X7B 

H. Liu, M.F. Ciraolo, C.P. Grey (SUNY at Stony Brook), J. Hanson (BNL), J. 

Martin and R. Sullivan (NC State) 

We have been studying a new class of CuAlC14 molecular sieves synthesized in one 

of our laboratories1 that undergo a phase change on sorption of ethylene and CO. We 

are able to expose materials to controlled partial pressnres of gas and monitor the 

resultant phase changes (Figure 1) with real-time X-ray diffraction methods. Both 

CY - CUA~CI~~ and O - CuAlCl4 contain large Van der Waals channels which are 

thought to be important in the reversible absorption of small gasses. As this time, 

the structure of the material formed on gas loading has not been determined, but 

must involve a significant rearrangement and opening up of the copper aluminum 

chloride framework to allow gas molecules to diffuse inside. Use of controlled gas 

pressnres allows to address questions such as: what partial pressnre of ethylene is 

required to force open the structure (and cause the phase change)? The kinetics of 

t h sorption ~ can then be monitored as a fnnction of pressure. 

1. 3.D. hIartin, B.R. Leafblatl, R.11. Sullivan, and P.D. Boyle, submitted to 

Inorg. Chem. 

2. K. Hiltlebrandt, P.G. Jones, E. Schwarzmann, G.hI. Sheldrick, Z. Naturforsch, 

37b, 1129 (1982). 

I In situ Diffraction Studies of the Akaganeite-hematite Reaction * I X7B I 

K. Nielsen, K. Stahl (DTU), J.C. Hanson, P. Norby (BNL) J.Z. Jiang (DTU) and 

J. van Lanschot (School of Conservation) 

Akaganeite FeO~-,(OH)l-,Cl,yH~O, is a commonly encountered corrosion prod- 

uct of iron. This compound is only formed and is only stable in the presence of 

chloride ions. In the absence of chloride ions, iron is stabilized to prevent further 

corrosion. In akaganeite the chloride ions are, together with water molecules, en- 

closed in channels in the structure, and may be released by washing. ion exchange 

or heating. When heated to temperatures as low as 425 K, akaganeite releases hy- 

drochloric acid, and the transformation to hematite, FezOs, starts to take place. 

In order to obtain information on the mechanism of hydrochloric acid release and 

to obtain a better understanding of the corrosion process, time-resolved X-ray syn- 

chrotron powder diffraction studies have been carried ont in the temperatnre range 

425 - 525 K, covering the whole transformation region. The structural examination 

are accompanied by therrnogravimetric ant1 differential thermal analyses and by 

AIoessbauer spectroscopy. 

- - .- -c - . - . 

1- 

Figure 1. In-sztu Sorption of ethylene in crCuAlC1~ (Ethylene pressnre = 10 psi). 

Fignre 1. Time-resolved powder pattern taken during 5 hour ramp from 150 to 

250C and then held at 250 for 3hr. 

* Thanks to SSF (DMRand CHE) and TS DOE BES. TS DOE BES contract DE.lC0276CH00016. Swedish SFR. Danish SSF

Time-Resolved, In-Sztu X-Ray Diffraction Studies of the Hydrother- 

mal Svntheses of Microporous Gallium Fluorophos~hates 

* 

X7B 

D. O'Hare, J.S.O. Evans, R. J. Francis, P.S. Halasyamani (Oxford U.) , P.l. Norby, 

J. Hanson (BNL) 

ULM-5 is a microporous oxy-fluorinated gallophosphate containing large 16- 

membered rings and interconnecting 8-membered rings.[l] ULM-5 is synthesised 

hydrothermally at 180°C. We have undertaken a study of the formation of ULM- 

5 under a variety of synthetic conditions in order to gain a greater understand- 

ing of the dynamics of crystal growth and nucleation. Early experiments at the 

SRS, Daresbury Laboratory, UK using time-resolved, in-situ energy dispersive X- 

ray diffraction indicated that a highly crystalline intermediate phase is observed to 

form which then subsequently reacts to form ULM-5. [2] In an effort to gain a greater 

understanding of the structural relationships between these phases we undertook 

an investigation of the synthesis of ULM-5 using monochromatic synchrotron radi- 

ation and a translating image plate detector (TIP) available on beamline X7B at 

the NSLS. 

Aliquots of the gel mixture were syringed into 0.7 mm quartz capillaries and 

heated to 160°C while time-resolved XRD patterns were collected with the TIP 

detector. The figures show two 3D plots of the evolution with time of the XRD 

patterns for successive ULM-5 syntheses. 

Despite being prepared in the same way, two experiments showed different be- 

haviour. Although in each case ULM-5 was the final product of the reactions, the 

time taken for complete crystallization was not the same. More dramatically, the 

behaviour prior to crystallization was completely different in each case. In Fig. la a 

mixture of two intermediate phases was observed which subsequently react to form 

the final ULM-5 product. In Fig. lb a single intermediate material is observed. 

In conclusion, these it in-situ experiments are a dramatic illustration of the com- 

plexity of hydrothermal syntheses, and how subtle changes in the reaction condi- 

tions, such as the use of slightly different starting materials or the reaction vessel, 

can greatly affect the course of these reactions. Nevertheless, be believe are results 

dramatically illustrate the unique ability of in-situ experiments to gain information 

not available using other techniques. 

1. G. Ferey, J. Fluor. Chem., 72 (1995) 187-193. 

2. R.J. Francis, S. J. Price, S. OIBrien, A. M. Fogg, and D. O'Hare, Chemical 

Communications, (1997),521. 

Figure 1. (a) (1eft)two intermediate (b) (right) one intermediate observed 

46 -3 

w * US DOE BES, Leverhulme Trust and EPSRC 

Phase Transformations in COMOO~ and NiMoOa Catalysts: Time- 

Resolved Synchrotron XRD Studies I x7B I 

- 

J.A. Rodriguez, S. Chaturvedi, J.C. Hanson (BNL), J.L. Brito and A. Albornoz 

(IVIC) 

The catalytic properties of cobalt and nickel molybdates have attracted a lot of 

attention in recent years. These novel materials exhibit interesting relationships 

between their structural and catalytic properties. At atmospheric presure, two 

phases of NiMo04 and CoMo04 are known to exist, designated as the alfa and the 

beta phase. The main difference between them is that coordination of MO~+ ions 

is octahedral in the alfa phase and tetrahedral in the beta phase. In both phases, 

co2+/~i2+ ions occur in octahedral sites. The catalytic properties of NiMo04 

are closely related to its structure. The beta phase is almost twice more selective 

for the dehydrogenation of propane to propene than the alfa phase. In a similar 

way, sulfided beta-NiMoO4 was found to be a much better catalyst for the HDS 

of thiophene than the sulfided alfa isomorph. In order to fully understand these 

catalytic processes, it is essential to understand both, the structural as well as the 

electronic properties of these molybdates. We carried out a detailed study of these 

properties using time resolved synchrotron X-ray diffraction. Investigations at X7B 

have recently established the feasibility of conducting sub- minute, time resolved 

XRD experiments under a wide variety of sample conditions (-190 C < T < 900 C, 

P

-3 A 

Structures from small single crystals of d, I-Ir(en)y [A13P4016]xH20 

and Ir(ch~n)~ /Al2P3Ol2] * 

X7B I AXAF Su vnchrotron Calibrations over 2010-6200 eV * I X ~ I A 

A. P. Wilkinson (Ga Tech), D. J. Williams (Kennesaw St.), and J. C. Hanson D.E. Graessle, A.J. Burek: A.M. Clark: J.J. Fitch, J.B. Sweeney (Smithsonian 

(BNL? 


We have been exploring the use of chiral chelate complexes as templates for the 

preparation of chiral solids. Our early work using simple Co(II1) complexes in the 

synthesis of AlPO and GaPO materials showed that chirality could be induced in 

We report progress in the reflectance calibrations of witness mirrors from the 

coatings of AXAF. AXAF is an acronym for NASA's Advanced X-ray Astrophysics 

Facility. The witness mirrors from AXAF are coated with some 350~ of iridium 

a growing framework using templates of this type. However, the range of Co(II1) 

complexes that can be used is limited by their hydrothermal stability. We have examined 

a number of strategies to produce template species with enhanced stability 

on 100A of chromium, on Zerodur substrates. Calibrations mere completed for four 

mirrors in the 2010-6200 eV range during November 1996. Problems with adjustments 

in the X8A nlonochromator horizontal alignment versus energy resulted in 

and found that the use of Ir(II1) in place of Co(II1) increases the maxi~nwn temperature 

at which the templates can be used by more than 50°C. Initital experiments 

a decision to calibrate only in the lirnited 2010-2400 eV range after the Jannary 

restart. The result was the completion of sixteen mirrors in the 2010- 2400 eV 

with Ir(II1)containing templates produced two new materials that could not be range, which irlclucles the iridium 11-V and hI-IV absorption features. Each caliprepared 

as single crystals suitable for use with a laboratory based diffractometer. 

A hemisphere of tlata was collcctetl on a 50 x 50 x 50 prn crystal of d,lbration 

was cornpletecl within a 24 hour run period. The X-ray beam was extremely 

quiescent through most of the run period, allowing 0111. gated monitoring rnoclc of 

Ir(en)3[Al~P.t016]xH20 wing 1.1167;l radiation (Pnna, 8.55, 21.93, 13.94;l). The operation to provide precision approaching 0.1% for reHectance measurements after 

data was processed using the HKL suite, and the structure was solved and refined normalization. This is as good as we have ever seen on X8,4. Calibration results 

ming SHELXTL. The material is closely related to d,l-Co(en)~[Al:~P,~0~~]xtI~0. for one mirror over the full X8A Si (111) energy range are given in the figure. The 

A hemisphere of tlata was collected on a 75 x 7 x 7 pm crystal of several traces represent tlata taken at differmt grazing angles. The 11-edge at)- 

Ir(chxn)3[A12P30,2] using 1.1167.4 radiation (P -1, 9.643, 12.242, 16.22211, 100.45. sorption features shown arc the most significant features appearing in the AXAF 

102.64, 105.16"]. The tlata was proccsscd as above. This material contains a new telescope reHecting efficiency. Significant EXAFS appear on the h1-IV edge, with 

2-374 amplitude oscillations versus energy extending over 300 eV. This re~riarkablc 

type of AlPO chain (Fig. I), related to one previously reported1 (Fig. 2). 

feature occurs in films and coatings of iritli~nn regardless of the quality or density 

1. I. D. Williams, .J. YII. Q. Cho. .J. Chcn and R. Xu, Chem. Corn. 1273 (1997). 

of the film. Further study and analysis of the EXAFS is urltler way. 

Figure 1. AlPO chain founcl in 

Ir(ch.;n)y [=\l2P3O 121 

* Partially supported by DOE under con- 

tract DE.4C0276CH00016 

Figure 2. -UP0 chain reported by 

IVilliams et al.' 

Figure 1. Reflectance calibrations over 2010-6200 eV for a single XXAF witness 

mirror. taken during the reported run period. 

This work is supported by the L-S D.O.E. and by S.4S-4 (S.4S8-40224).

AXAF Synchrotron Reflectance Calibrations 2010-2400 eV - Completion 

Report * I x 8 1 ~ 


Astrophysical 0bservator~)and R.L. Blake (R&D Services, Prop.) 

We report the completion of calibrations on a total of 46 witness mirrors in the 

data range 2010-2400 eV. The final 20 mirrors on the schedule were completed 

during our second run period of 1997 on X8A. The 2010-2400 eV range includes the 

M-V and M-IV edges of iridium, two of the most important features in the entire 

AXAF mirror efficiency spectrum. Our measurements typically obtained 0.2-0.3% 

experimental noise levels during this run, indicating a very stable and quiescent 

X-ray ring operation. Years of work on these issues with the NSLS accelerator staff 

have paid off well. The figure gives the calibration data taken from a typical AXAF 

witness mirror. The several traces are data taken at different grazing angles. These 

data are to be reduced to optical constants using a Fresnel equation model with 

uniform layers and a modified Debye-Waller factor roughness correction. The optical 

constants will be used in modeling of the AXAF calibration to be compared with 

data taken from the actual flight optics. Optical constants provide the advantage of 

removing angular information from the reflectance data, allowing a full calibration 

versus energy and angle with a minimum of reflectance data. 

1 ~ 1 1 1 1 1 1 1 1 / 1 1 < / 1 1 1 1 < 1 1 1 1 1 1 1 1 1 1 1 1 1 1 

2000 2100 2200 2300 2400 

PHOTON ENERGY (eV) 

Figure 1. Reflectance calibration for a typical AXAF witness mirror over 2010-2400 

eV, showing the M-V and M-IV edges of Ir. 

P 

-4 

u1 * This work is supported by the US D.O.E. and by NASA (NAS8-40224). 

I AXAF Synchrotron Reflectance Calibrations over 2010-6200 eV - I , , I 

RON 

I Year 1 * 



AXAF witness mirrors are coated with 350 A iridium upon 100 A chromium, 

deposited on a Zerodur substrate. We report our first sixteen months' progress on 

reflectance calibrations of AXAF witness mirrors in the 2010-6200 eV range using 

beamline X8A (1995-1996). Data quality with 0.2-0.4% precision is nearly always 

attainable. Noise problems from the source, which are particularly noticeable with 

the aperturing on this beamline, have largely been cured by the accelerator science 

staff. At best, data acquistion over four energy ranges which collectively cover 2010- 

6200 eV, may be completed in four days. Efforts to improve the data acquisition 

timing are in progress. Included in the efforts are a new data aquisition program 

based on LabView software from National Instruments, Inc., and some type of semi- 

transparent flux monitor which can replace the gated PIN diode normalization 

method we have used during the first year. (Please see adjoining abstracts for 

progress in these areas.) Through the first sixteen months of the X8A AXAF 

calibrations, we have calibrated some 13 mirrors. There are 31 mirrors remaining 

to be calibrated over the full range to meet our calibration goals for AXAF. Iridium 

optical constants have been derived from some of these data using a Fresnel Equation 

model with uniform layers and a modified DeBye-Waller factor correction for surface 

roughness. Figure 1 gives optical constants derived in the 2010-2400 eV range for 

several of these mirrors. This range includes the iridium M-V and M-IV absorption 

features. Different mirrors give slightly different optical constants. It appears from 

the data that a few angstroms of some contaminant are present in varying depths 

on the several mirrors included. 

2000 7100 7700 2300 zaoo 

PHOTON ENERGY (rV) 

Figure 1. Optical constants P(E) determined from reflectances of several mirrors 

2010-2400 eV. The black dots are average values of five mirrors. Diamonds give the 

Henke tables' values. 

* This work is supported by the US D.O.E. and by NASA (NAS8-40224).

-4 

o 

AXAF Synchrotron Reflectance Calibrations 2250-2900 eV - Com- 

( Scattering Studies of AXAF Witness Mirrors * 1 X ~ C 

pletion Report 

X8A 

* R.L. Blake (R&D Services, Prop.), A.J. Burek, and D.E. Graessle (Smithsonian 

Astrophysical Observatory) 

D.E. Graessle. A.J. Burek, J.J. Fitch, J.B. Sweeney (Smithsonian Astrophysical 

Observatory), and R.L. Blake (R&D Services, Prop.) 

We report the completion of calibrations on some 48 iridium-coated witness mirrors 

in the 2250-2900 eV energy range. which includes the sharp, narrow hI-I11 

absorption feature and considerable EXAFS on the XI-V and RI-IV edges. We have 

reduced the calibration time to one mirror per eleven-hour shift, using a doublewindow 

ionization chamber in the vacuum as a flux monitor, and a new data acquisition 

program based on LabView. \Ve can now complete the remaining calibrations 

in approximately 65 eleven-hour shifts on X8A, thereby conlpleting the calibrations 

slated for this bearnline. The relative response between the Si PIN tliotle which measures 

the reflected flux, antl the double thin-Be-winclow ionization chamber monitor 

is constant to within 1% in all cases, but usually is within 0.4% from the start to 

the finish of any given calibration. The variation in this normalization is cnrrentlv 

attributed to the variation in the vertical extent antl bifnrcation of the X-ray beam. 

The vertical extent changes as the upstream mirror on XXA cycles thermally dnring 

each fill. The data quality, exclntlir~g this small slow variation in normalization, 

is extremely good, and is mnch less sensitive to temporal instabilities in thc XXA 

intensity, a problem which has occasionally cost onr team time when using our old 

gatctl Si PIN tliotle monitoring system. Exanlple data are given in the fignre. The 

precision in the data, is at thc 0.1% level, the best mrer seen from this bea~nline at 

these er~ergies. 

Figure 1. A typical reflectance calibration over 2250-2900 eI7 of an =\X=\F witness 

mirror. showing the narrow iridium 11-111 absorption feature. 

* This work is supported by the L*S D.O.E. and by ?J--lS.-l under contract number 

X.-lS8-10224. 

A preliminary x-ray scattering study has been conducted on one of the AXAF 

witness mirrors that we are calibrating. The study was intended to determine 

whether sample scattering can be reliably measured separately from slit scattering 

and over what range of angles with respect to the specularly reflected beam. The 

same reflectometer test station was used that is routinely employed for all our 

reflectivity calibrations at NSLS. Data were taken at 10 keV with the Ir coated 

witness sample at the critical angle (8.12 milliradians). A 100 micrometer entrance 

slit upstream of the sample and a 105 micrometer scraper slit between the entrance 

slit and sample define the beam received by a 2.5 micrometer detector slit. The 

detector was scanned through the direct bean1 with sample removed to get the 

slit scatter profile, then through the reflected bean1 to get the combined slit and 

sample scatter profile. Shown below as the inner, tlashed curve is the normalized 

direct beam profile shifted to be centered on the reflected beam profile (the outer, 

solid curve). On the tlirect beam profile one sees the scattering prirnarily from the 

entrance slit ~mtil it is clipped by the scraper slits at *I000 ms from the direct beam 

centerline. To cletermine the sample scatter profile without the slit contribntion 

one must invert the direct beam profile arour~tl the reflected bean1 specular peak 

and then snbtract the inverted direct beam profile from the reflected beam profile. 

\\.:ithout doing the inversion and snbtraction one can scc the study goals were met. 

The sarnplc scatter contribution can be tleterminetl to acceptable accuracy to within 

300 ms of the specularly reflected peak, or 1.3 rnilliratlians. This preliminary work 

tlernonstrates that a full scattcri~~g study on AXAF saruples is justified. 

Figure 1. Diffuse X-ray scattering intensity from an .\X.iF witness mirror. 

* This work is supported by the L*S D.O.E. and by S.-lSA (S.-lS8-40221). 

1

I AXAF Synchrotron Reflectance Calibrations 5-12 keV * I x8c I 


Astrophysical Observatory), R.L. Blake (R&D Services, Prop.) 

We report significant progress toward the completion of the 33 scheduled witness 

mirrors for calibration over 5-12 keV on the X8C beamline. In all, 29 of the orignally 

slated 33 AXAF witness mirrors have been calibrated successfully in this energy 

range. A very significant addition to our configuration has made this progress 

possible. A double-thin-Be-window ionization chamber filled with one atmosphere 

of Ne has allowed simultaneous monitoring of the incident flux with the detection 

of the reflected flux by Si PIN diodes. The ion chamber allows data points to be 

taken in a period of approximately six to eight seconds each, whereas our previous 

method of gating PIN diodes in and out of the beam required 20-25 seconds per 

point. This is an improvement of almost a factor of three. Data quality is not only 

uncompromized, but is in fact improved. (See figure 1 below.) Disparate points 

frequently occur using the gated monitor because of significant flux variations due 

to monochromator settling and thermalization which happens at certain energies 

when the monochromator is initially set or moved to those energies. The change 

in flux may be as much as 5% at such points, and this ramping may occur up to 

10 seconds after the monochromator stepper motor has stopped. The ion chamber 

essentially eliminates this problem. Hence, we have completed 18 mirrors in the 

Se~tember 1996 data run on X8C. Further progress is reported in the adjoining 

ab'stracts. 

4.0x103 6 0 x10~ 8.0x103 1.0~10~ 1 2 x10~ 

PHOTON ENERGY (eV) 

Figure 1. Reflectance calibration data from an AXAF witness mirror using the 

ionization chamber monitor. The traces give data from different grazing angles. 

-4 

-4 * This work is supported by the US D.O.E. and by NASA (NAS8-40224). 

I AXAF Synchrotron Reflectance Calibrations 5-12 keV * I X ~ I C 

D.E. Graessle, A.J. Burek, J.J. Fitch, J.B. Sweeney (Smithsonian Astrophysical 

Observatory), and R.L. Blake (R&D Services, Prop.) 

We report the completion of scheduled calibrations on the X8C beamline for 

AXAF witness mirrors over 5-12 keV. The thin-window ion chamber continues to 

give consistant normalizations with Si PIN diodes, allowing simultaneous monitoring 

and reflectance measurements. The final five AXAF witness mirrors originally slated 

for calibration have been completed during this run. Seven additional angles were 

added to the procedure for energy scans, which allow better determination of optical 

constants, particularly in the in the 10-12 keV range. This latter range includes 

the very sharp, strong L-I11 absorption feature for iridium. (See Fig. 1.) Optical 

constants P(E) determined from the reflectance data are in Fig. 2, including a 

comparison with data from Henke, et al., Atomic Data and Nuclear Data Tables, 

vol. 54(2), p. 181 (1993). (Our fitted S(E) is consitently within 2% of the tabulated 

values.) The P values exhibit a dependence on the roughness of the flat measured, 

which is not physically reasonable. Further study of our mirror scattering and 

modeling thereof are in progress. 

REFLECTANCI 

0 0 0 m 

8 8 1 nx10-61 , , . , , , , . , , , , , . , , I , , , , , , , , , , , , .I 

8ox?o3 9ox103 I ox1n4 I lxlon 1 zx104 

Figure 1. Reflectance calibration over 5- PHU oh LN~KGY (r~) 

12 keV of a 3A roughness witness mirror. 

Figure 2. P(E) derived from AXAF mir- 

* This work is supported by the US 

D.O.E. and by NASA (NAS8-40224). 

rors with two different surface roughness 

values.

4 

03 I Structural Studies of Gene 5 Protein-ss DNA Complexes 

-- 

T. C. Terwilliger. R. G. Nanni (LANL) 

VQ~. . . 

Single-stranded nucleic acid-binding proteins play roles in key cellular processes 

such as DNA replication, recombination. repair, and control of RNA translation. 

This project has focussed on determining the crystal structures of complexes between 

gene V protein and oligonucleoticles of lengths from 4 to 16 nucleotides. iVe 

have obtained crystals of a number of these complexes and have collected x-ray 

diffraction data on those that diffract to high resolution. At this point we have collected 

x-ray diffraction datasets to a resolution of at least 3.5 A for the 6 different 

gene V protem-oligonucleotide complexes. 

IVe have used the structure of the wild-type gene V protein that we determined 

previously to solve the structure of the protein portion of one complex crystal containing 

a 16-mer oligon~~cleotide. This complex crystallized in space group R3 and 

the asynlrnetric unit of the crystal contains 4 monomers of the protein. The standard 

R-factor for this structure after rigid-body refinement of the protein portion 

alone is 0.39. indicating that the solutiori we have obtained is likely to be correct. 

iITe are now in the proccss of using tlifferer~ce Fourier methods and atomic refinement 

to determine the location of the bound ssDNA in these crystals. 

I TATA Binding Protein: Interactions with DNA I X ~ A 

h1. Brenowitz, M. Sullivan, B. Sclavi, S. Naleknia: S. hIoller, B. Gilden (AECOhI) 

TBP is a component of the nucleo-protein complexes required for the initiation 

of transcription by each of the three eukaryotic RNA polymerases. The binding of 

the "TA4TTA Binding Protein" (TBP) to specific promoter sequences called "TATA 

boxes" is a key step in the initiation of transcription of genes transcribed by RNA 

polymerase 11. The nucleotide sequence of 'TATA boxes' is variable among naturally 

occurring promoters. Although promoters containing 'TATA boxes' that bind 

TBP with high affinity are generally transcribed efficiently, there is not a direct 

correlation between TBP binding affinity and transcriptional activity. 

A mechanism has been proposed for the association of TBP with DNA. 

KI ka 

TBP + DNA* [TBP - DN4]* + TBP - DNA (1) 

analogous to that demonstrated for E. coli RNA polymerase. The prrsence of a 

TBP-DNA intermediate (a rapid equilibrium, K1, followed by a slow kz) was inferred 

by extrapolation to infinite [TBP] by double-reciprocal plotting of k,b, versus 

[TBP]. The hard rnixing protocols used in these studies limited the TBP concentrations 

that could be investigated and hence the accuracy of the extrapolation 

requirctl for the tletcrrriirlation of the value of kz. 

Stopped-flow kinetics st,utlies of TBP pronmter interactions condl~cted at higher 

TBP cor~cerrtrations by "footprinting" (E4 promoter) antl fluorcscencc anisotropy 

(SIL promoter) were inconsistent with thr prrscncc of significant concentrations of 

the tliff~~sion-limited intermediate complex of eq. 1. Fwthrrrnore, stoppctl-flow fluorescence 

resonance energy transfer (FRET) st~~dics of TBP birding to nntl he~ding 

ttlc hIL promoter did not reveal a tliffi~sion-lirnitctl intcrmctliatc. A TBP birding 

~nechanisrn consister~t with these stutlirs is that only a small fraction of the TBP- 

DNA tliffi~sion-limited "encounter cornplrxes" rapidly progresses to for111 stable, 

srq~~er~ce-specific complexes. This model ran be rcprcsrntctl as 

k 1 

k2 

TBP + DXA TBP -- DNA i TBP - DUh (2) 

" Enco~~nter" 

k- 1 

complez 

where the first step of the reaction is the formation of the encounter complex. 

The encounter complex represents the diffi~sional encounter of two reactants that 

become trapped within the same solvent cage during which time they suffer a large 

number of collisioris prior to separating or proceeding down the reaction pathway. 

It is important to note that in this representation of the binding reaction. K1 is a 

quasi-tliermoclyna~~~ic constant depicting the events prior to the chemistry of the 

reaction antl ka is the rate constant of the reaction. Time-Resol\-ed hydroxyl radical 

footprinting will be utilized to test these mechanisms of TBP-DS.1 interactions. 

1

Single Band Densitometric Analysis Synchrotron X-Ray Footprinting 

Autoradiograms I xgA I 

M. Brenowitz, T. Wexler and E. Jamison (AECOM) 

A key issue to be resolved for the analysis of synchrotron x-ray "footprinting" 

kinetics experiments is the development of algorithms for the "band-by-band" den- 

sitometric analysis of the gel electrophoresis autoradiograms that are the primary 

data of these experiments. While the current procedures, in which groups of bands 

are grouped into "blocks", has been sufficient for the analysis and interpretation 

of the *OH protections that have been determined in our initial studies of the Te- 

trahymena ribozyme, insight into more subtle changes of structure requires the im- 

plementation of " band-fitting" protocols originally developed in our laboratory for 

thermodynamic studies using *OH and 5-phenyl-phenanthroline as probes of DNA 

conformation that occur in sequence-specific protein-DNA interactions. Implemen- 

tation of these protocols have been greatly facilitated through the development by 

Dr. Thomas Tullius and his co-workers of a band-fitting program (GelExplorer) 

with an interactive graphical interface interactive that runs within the IRIS Ex- 

plorer environment. The basic algorithm is that the optical density (OD) of each 

lane on an autoradiogram is scanned in the direction of electrophoresis across the 

width of the lane. The OD values determined for each scan are fit to individual 

curves within the selected lane. The procedure is analogous to spectral deconvo- 

lution. Following fitting, the areas of the fitted curves are summed for each band 

and a histogram can be generated relating relative band density with the nucleotide 

present at that position in the nucleic acid. The results obtained by this proce- 

dure for the DNA containing a 'TATA Box' (the binding site of the eukaryotic 

transcription factor TBP) shows that the decrease in the relative band densities 

for the sequence 'AAAA' is consistent with the assumption of a bent configuration 

by this sequence. Similar data sets obtained at temperatures from 15 - 45 OC are 

being compared with solvent accessibility calculations of this DNA obtained from 

molecular dynamics calculations. The goal of this project is to correlate changes in 

DNA conformation with the temperature dependencies of the thermodynamics and 

kinetics of DNA binding by TBP. *OH cleavage data sets have been obtained for a 

number of different 'TATA box' sequences that display unique thermodynamic and 

kinetic signatures. 

I A Resource Dedicated to Time-Resolved X-Ray Footprinting I X ~ I A 

M. Chance, M. Brenowitz and M. Sullivan (AECOM) 

Hydroxyl radicals (*OH) can cleave the phosphodiester backbone of nucleic acids 

and are valuable reagents in the study of nucleic acid structure and protein-nucleic 

acid interactions through footprinting studies. Irradiation of solutions by high flux 

white light x-ray beams based on bending magnet beamlines at the National Syn- 

chrotron Light Source (NSLS) yields sufficient concentrations of *OH so that quanti- 

tative nuclease protection (footprinting) studies of DNA and RNA can be conducted 

with a duration of exposure in the range of 10 - 20 milliseconds. 

To provide expanded access to this technology, beamline X9A at the National 

Synchrotron Light Source has been constructed along with a dedicated stopped flow 

instrument to allow footprinting studies for our expanded group of investigators. 

The beamline accepts up to 5 milliradians of white beam, with a flu density of 

10' photons/s/mm2/0.07% bandwidth over an effective energy range of 3-30 keV. 

The completion of the beamline has enhanced the productivity of this core project, 

accelerating both the core and collaborative research programs tremendously. Our 

Resource is the world leader in this technology and the availability of a dedicated 

beamline will continue our leadership in this area. We are now routinely conducting 

footprinting studies on 10-20 milliseconds and longer timescales with our stopped 

flow device and have made major advances in understanding RNA folding.

GO 

3 I The Folding of an Immobile DNA Branched Junction I X ~ I A 

RI. Chance, B. Sclavi. M. Brenowitz (AECOR'I), N.C. Seeman, and H. Yan (NYU) 

The Holliday junction is a central intermediate in the process of genetic recombination. 

This is a four-stranded DNA molecule, in which the four strands pair to 

form four double helical arms that flank a branch point. The site of the branch point 

in naturally occurring Holiday junctions is unstable, because it is flanked by twofold 

(homologous) sequence symmetry that permits the junction to relocate through an 

isomerization known as branch migration. If the symmetry is eliminated in synthetic 

molecules, the site of the branch point is stable. In the presence of I\Ig cations, the 

junction folds into a structure in which the four arms stack on each other pairwise, 

to form two double helical domains; two strands adopt a roughly helical structure, 

and the other two strnntls cross over between the two domains. In the absence of 

hIg cations, the four arms adopt a fourfold symmetric arrangement. The hydroxyl 

radical cleavage pattern is sensitive to the folding of the junction in the presence 

of hlg. Relative to their pattern in linear duplex DNA, the two crossover stra~lds 

are protected from attack in the two-domain structure. Likewise, four nl~cleotides 

3' to the branch point, the helical strands demonstrate protection, because they 

occlude each other there. Both protections appear to be lessened in the abscncc of 

magnesium. Hence, this is a system whereby the kinetics of the foltling of this key 

intermediate shol~ld be measurable through these reporter protection diffrrences. 

I Time-Resolved Synchrotron X-Ray Footprinting I X ~ I A 

MR. Chance. M. Sullivan, B. Sclavi, &,I. Brenowitz (AECORI), and S. Woodson 

(Univ. of Maryland) 

Hydroxyl radicals (*OH) can cleave the phosphodiester backbone of nucleic acids 

and are valuable reagents in the study of nucleic acid structure and protein-nucleic 

acid interactions through "footprinting" studies. Irradiation of solutions by high 

flux "white light" x-ray beams based on bending magnet beamlines at the National 

Synchrotron Light Source (NSLS) yields sufficient concentrations of *OH so that 

quantitative nuclease protection ("footprinting") studies of DNA and RNA can be 

conducted with a duration of exposure in the range of 10 - 20 milliseconds. The 

utility of this timescale for rmcleic acid cleavage is demonstrated by synchrotron 

x-ray time-resolved "footprinting" analyses of the h1g"-dependent folding of the 

Tetrahymena themophilia L-21 Sca I ribozynle RNA. 

hlany macromolecnlar folding reactions, such as the Rlg2+-dependent folding 

of the P4PG domain of the Tctmhymena thermophilia group I intron, occur on 

tin~escales shorter than one second. Kinetic progress curves describing the millisecond 

foltling of P4-PG within thr L-21 rihozyme have been obtained using a new 

*OH "footprinting" technique, stopped-flow synchrotron x-ray "footprinting". The 

foltling of P4-PG is a highly co~lcertcd reaction; the regions of *OH protection within 

the interior of the folded domain appear at rates of < 1.0 sec-'..OH protectior~s 

within the P5c sub-domain appear at rates of = 2.0 secpl, suggesting that foltling 

of this subdomain is the initial step in the folding pathway. Thr rates of *OH 

protection of the "triple hclix" junction between P4-PG and the P3-P7 tlomnin antl 

those protections in P4-PG ascribed to interaction with the PO domain at ratcs of zz 

0.3 secp'. These results suggrst that these tertiary interactions guide the folding of 

the catalytic core against an extensively folded P4-PG domain. This stopped-flow 

approach to "footprinting" will be widely applicable to the kinetic analysis of many 

ru~cle~c acitl folding a~ld protein-nucleic acids birltlirlg reactions. 

Since RNA folding progress curves over tirnescales from 20 milliseconds to several 

minutes ha\re been obtained for nearly 20 regions of the ribozyme. this research 

provides an unprecetlentetl structural kinetic picture of the foltling of a large rnacromolecule. 

Synchrotron x-ray "footprir~ting" is a new approach of general applicability 

for the study of time-resolved structural rhangrs of nucleic acitl conformation 

antl protein-nucleic acitl complexes.

Fast Folding of the Tetrahymena Ribozyme: Mutants and P4-P6 Do- 

main Folding I xgA I 

M.R. Chance, M. Sullivan, B. Sclavi, M. Brenowitz (AECOM), S. Woodson, M. 

Deras (U. of Maryland), J. Williamson, and M. Rook (MIT) 

To further dissect the folding mechanism of the Tetrahymena ribozyme, we have 

explored two avenues of research. One is to examine the folding of the isolated 

P4-P6 domain, which is seen to fold on the sub-second timescale in the presence 

of other ribozyme components. This phase of the research is in conjunction with 

Dr. Woodson's lab at the University of Maryland. The second approach, in col- 

laboration with Dr. Williamson's lab at MIT, involves examining the folding of 

several fast-folding mutants of the Tetrahymena thermophila group I intron. Dr. 

Williamson's group is currently characterizing the temperature and urea depen- 

dence of folding of these mutants, using their oligo-hybridization method, which 

probes the formation of helix P3 in the ribozyme. In order to measure the rates of 

folding of the rest of the 400 bases-long RNA, Martha Rook, a graduate student in 

Williamson's lab has begun time-resolved x-ray footprinting experiments on these 

mutants in collaboration with the Resource Center. 

( Time-Resolved X-Ray Footprinting of Cytochrome c 1 X ~ 1 A 

I. Kravtsov, S.D. Maleknia and M. Chance (AECOM) 

Understanding the folding kinetics of proteins are vital in revealing their bio- 

logical functions and structures. Spectroscopic methods used to date have been 

quite helpful in characterizing transient-intermediate structures of proteins, but 

new methods to investigate tertiary structure changes are needed. Synchrotron x- 

ray footprinting techniques enable millisecond time-resolved structural changes in 

nucleic acid conformation and protein-nucleic acid complexes to be studied. This 

approach in conjunction with mass spectrometric sequencing methods are being 

used to study folding kinetics of cytochrome c. Hydroxyl radicals generated by 

x-ray radiolysis of water induce detectable amino acid modifications of cytochrome 

c within 4 millisecond. Deconvoluted electrospray ionization mass spectra reveal 

that the prominent modification results in ions at +16 u intervals above the molec- 

ular weight of unmodified protein. The nature of these modifications are being 

identified by proteolysis and mass spectrometric mapping experiments, and are cor- 

related with the solvent accessibility residue map of cytochrome c to reveal the 

protein structure at various solution conditions. The aromatic, heterocyclic, and 

sulfur containing amino acid residues are most reactive to hydroxyl radicals.

I 

CO 

p3 I 

Synchrotron X-Ray Induced Modifications of Peptides I X ~ I A 

S.D. Maleknia and M. Chance (AECOM) 

Synchrotron x-ray studies of peptides are being investigated to characterize the 

reaction mechanisms, and to construct a data base of the reactivity order, for each 

class of amino acids. These studies include anaerobic and ''0 isotope experiments. 

The order of reactivity of amino acids at various pH conditions or in the presence 

of denaturing agents (urea, KCI, guanidine hydrochloride) are also being examined. 

This study provides fundamental information necessary for protein footprinting experiments. 

The racliolysis of water by x-rays produces a high flux of free electrons and hydroxyl 

radicals in a millisecond time scale. Random sequence peptides (10 to 25 

mhI in water) containing 5 to 20 amino acid residues were exposed to the x-ray 

bean1 (X-9B) for 4, 16, 50, or 100 ms. Analysis of these peptides by mass spectro~netry 

using matrix-assistecl laser desorption or electrosprav ionization techniques 

revealed modifications to the pepticle within 4 ms. The major peptitle motlification 

resdts in ions at fl6 u intervals above the molecular ion of the unmociified peptitle. 

hIass spectra of peptides containing phenylalanine residnes revealed multiple 

modifications tletectetl at +I6 u inter\ds after 50 to 100 rns x-ray exposure. i\Iass 

spcctrorrletric scqncncing identified that the phenylalanine residues were modified 

bv addition of 16 11. 

I The structure of an Actin-crosslinking domain from Human Fimbrin I X9B I 

S. Almo, S. Goldsmith, M. Sullivan, and A. Fedorov (AECOM) 

Actin crosslinking proteins organize filamentous (F-) actin into higher order assemblies 

such as bundles and networks which are important for biological processes 

including cell motility, cytokinesis and tumorigenesis. Fimbrin is a representative 

member of the largest superfamily of actin crosslinkers which is characterized by a 

conserved 275 amino acid F-actin binding domain. We have cleterminecl the crystal 

structure of the N-terminal actin binding domain of human fimbrin (ABDl) 

to 2.4resolution, which represents the first high resolution structure of an actincrosslinking 

domain. Initial characterization of ABDl crystals was performed using 

synchrotron radiation at Brookhaven National Laboratory, Beamline X9B. where 

the crystals diffracted to at least 1.9Areso1ution. ABDl is an ellipsoid molecule of 

dimensions -fi0x40x40~&~, and has a novel fold composecl of two calponin homology 

(CH) subdomains. CH domains mav serve to target a nomber of proteins) including 

signaling proteins) to cytoskeletal components. The two CH domains in ABDl are 

connected by a central alpha-helix, and are specifically oriented by inter-subdomain 

hydrophobic and ionic contacts. The crystal structure of ABDl has allowed for the 

nlapping of peptide segnlents implicated in F-actin binding. as irlentifietl by peptitle 

binding and deletion mutation analysis. The locations of snppressor mutations in 

the yeast homolog of firnbrin (sacfip) snggest that the interaction between ABDl 

and F-actin is mcdiatetl bv a conformational rearrangement i~wolving the relative 

orientation of the two CH tlornains. The crystal structure of ABDl provides a starting 

point for the constrnctiori of a tlctailed atomic rnotlel of F-actin crosslinking by 

rnt:rnb~rs of the entire superfamily of proteins.

Fj 

m 

6 

Frozen Solutions and Vectorially-Oriented Single Monolayers of Ori- 

X9B 

ented RIembrane Herme Proteins 

J.K. Blasie, A. Edwards (U. of Pennsylvania) and K. Zhang (IIT) 

Both peripheral (soluble) and detergent-solubilized integral membrane proteins 

can be tetered to the surface of inorganic substrates via bifunctional organic chain 

molecules possessing a headgroup specific for the substrate surface and an endgroup 

specific for one or more residues exposed on the protein's surface. Such tethering 

can provide a single vectorially-oriented monolayer of the fully-functional protein on 

the surface of the solid substrate resulting in an ideal form of the protein for closely 

correlated structural and functional studies, the former employing both x-ray spectroscopy 

and x-ray diffraction. Over the past year, we have performed polarized 

Fe-EXAFS studies on such vectorially-oriented single morlolaycrs of cytochrome c 

in order to determine the utility of such measurements for cleternlining the orientation 

of the cytochrome's heme group relative to the plans of the monolayer. as 

compared with that of analogous linear tlichroism studies of the heme's optical absorption 

transitions. These stutlies have recently been published. In addition, me 

have performed both Fe-EXAFS antl Zn-EXAFS stutlies on frozen solutions of an 

entirely synthetic motlel ~netalloprotein (or "maquette") basetl on a four alpha-helix 

bundle motif containing by design specific birding sites for four either iron porphyrin 

or zinc porphyrin groups. The a~lalvsis of ttlcsc tlata are in progress. These studies 

are essential to establish the precise nature of the actual coordination of the metal 

atom in such "maquettes" as a prelude to polarized EXAFS stutlies on vectoriallyoriented 

single monolayers of sllch moctel metalloproteins. Overall. these structural 

stutlies are essential to ur~tlerstantling the nature of both intramoleclllnr antl intermolecular 

elcctron transfer phenomena exhibitrd by these merrrbrar~r proteins (as 

we11 as rnotlcls and complexes thereof), and thc coupling of these phenomena to 

the generation of trarlsrrlcmbrane electrochemical potentials ant1 biological energy 

conservatiorl. 

I AUTOFIT 1.0. A New Software for XAS Global Mapping I X ~B I 

M. Chance, E. Scheuring, Wu-Xin Huang (AECOPVI) 

Our global mapping procedure, where crystal structure coordinates are refined 

to XAS data using the ab initio XAS code FEFF 6.01, continues to be used ancl 

updated. In the programs. a grid of hundreds of simulations are directly compared 

to the experimental data without the use of non-linear least squares fitting prce 

cedures to find the interatomic distances. Instead, each simulation is performed 

with different interatomic distances. The emphasis is on mapping the local and 

global minima and providing a detailed visual picture ancl error analysis in the 

comparison of alternative structures. The three dimensional structural coordinates 

utilized in the simulations are based on crystal structure models derived from struc- 

tural databases. Thus, a particular geometry for the metal site is incorporated in 

this choice. Alternative structures with different geometries can also be selected, 

processed, antl compared. This makes the structural assumptions about the site 

explicit antl they must be justified based on ancillary structural information. Our 

suite of programs (called AUTOFIT 1.0) vary selected bond distances, compare the 

resulting ab initio simulations to the experimental tlata, and compute antl plot a 

figure that displays 400-500 alternative solutions simultaneously. These programs 

are available to outsitle users free of charge ancl have been readied for release along 

with a manual for using the code. In addition, we have recently completed ;t UNIX 

based version of the code, along with the original PC basetl version.

Structural Studies of Optically Rubbed Polymers X9B I Coordination of Co (11) Protoporphyrin-Substituted Hemoproteins I Xgfl I 

P.A. Heiney, S.S. Ghosh, O.Y. Mindyuk and M. Stetzer (U. of Pennsylvania) 

C. Lee, E. Scheuring, M. Chance and J. Peisach (AECOM) 

We have measured the X-ray reflectivity of rubbed polyimide films used for liquid 

crystal alignment. Both mechanically rubbed polyimides and polyimides "rubbed" 

by linearly polarized UV light were examined. The mechanism for liquid crystal 

alignment in the optically rubbed films is still unclear; suggested mechanisms in- 

clude either the formation of large-scale "ripples" due to anisotropic contraction 

which in turn interact with the liquid crystal, or reorientation of individual poly- 

mer molecules. The mechanical rubbing process creates microgrooves on the surface 

of the polyimide film, which on average run parallel to the rubbing direction. These 

grooves result in anisotropic off-specular X-ray reflectivity features. The analysis 

of the specular reflectivities obtained from these films will produce a comparison of 

the roughness associated with both mechanically and optically rubbed films, parallel 

and perpendicular to the rubbing direction. We use specular reflectivity, together 

with the anisotropic character of our resolution function to extract the anisotropy 

in the roughness along the film surface. 

Investigations of Co(II1) porphyrin complexes have in part been motivated by 

their use as models for cobalamin species such as coenzyme BIZ, and in part by their 

reactivity with nucleic acids. Interactions of Co(II1) porphyrins with biomolecules 

are governed by their axial ligations and no Co(II1) porphyrin complex with a single 

strong field, s-donating axial ligand, such as nitrogen, has been reported. Unlike 

Co(II1) porphyrins, pentacoordinate Fe(II1) porhyrins are found in many hemopro- 

teins and have also been synthesized. For example, the met (oxidized, ferric) form of 

the His64(r)Leu mutant of the oxygen-carrying protein myoglobin [Mb(H64L)] con- 

tains a pentacoordinate metal with an axial histidine ligand, whereas in the native 

protein, the second axial ligand is a water molecule. No water molecule was found 

near the metal in the mutant. In this study, Co(II1) protoporphyrin-substituted 

Mb and Mb(H64L) are studied by x-ray absorption spectroscopy. The absorption 

edge energy for both proteins occur near 7729 eV, suggesting that both are hexa- 

coordinate. The sixth ligand of Co(II1)-substituted Mb has been suggested to be 

His64, rather than water as in the Fe(II1) protein. Since neither His64 nor wa- 

ter (presumably) are present in the Co(II1)-substituted mutant, the current results 

are surprising. Further studies are being conducted to identify the sixth ligand in 

Co(II1) Mb(H64L).

tj 

03 

t, I Biological hIetal Clusters 1 X~B 

1 

RI. Maroney, S. Choudhury, C. Allan, Z. Gu, G. Davidson, and K. Bose (University 

Enzyme and protein active sites containing two or more interacting metal centers 

now figure prominently in metallobiochemistry. Systems containing metal clusters 

composed of Fe atoms (e.g. ferrecloxins. sulfite reductase, hemerythrin, ribonucleotide 

reductase, methane monooxygenase). Cu atoms (e.g. hemocyanin, tyrosinase, 

cernloplasmin, cytochrome oxidase), RIn atoms (photosystem 11, catalase) and 

more than one element, or heteropolynuclear clusters (e.g. nitrogenase-hIo,Fe: cytochrome 

oxidase-Fe.Cu; hydrogeriase ancl carbon monoxide dehgdrogenase-Ni,Fe), 

have been identified. The ultimate goals of this project are to elucidate the structures 

of metal clusters in metalloproteins, to determine the roles these clusters serve 

in the function of the protein, antl to unclerstand how nature designs a cluster for a 

specific purpose. This knowledge will provide a detailed understanding of biological 

processes antl will aid in the design of pharmaceutical enzyme inhibitors antl catalysts 

for various reactions. During the current report period, we have completed 

studies cornparing the structures of the Ni sites in hydrogenases from six different 

species of bacteria poised in a number of different retlox states. These studies reveal 

the overall similarity of the Ni sites, with the exception of the enzyme from Alcaligenes 

eutrophus, which undergoes a large change in structure upon redox cycling. 

\Ve also hare exanlined sarnples of Chromatiurn vinosum hytlrogenasc in eleven tlistinct 

states. These studies corroborate and extend the previous studies donc on the 

hptlrogenase from Thiocapsa roseopersici~m, and specifically confirnl the absence of 

features indicative of CO ligation in the CO-inhibitctl cnzyme. 

EXAFS Characterization of the Zinc Binding Site in Cobalamin- 

X9B 

Dependent Methionine Synthase * 

I - I I 

K. Peariso, C.W. Goulding, R.G. Matthews, and J.E. Penner-Hahn (U. of Michigan) 

Cobalamin-dependent methionine synthase (ILIetH) from E. Colt is an enzyme 

which catalyzes the transfer of a methyl group from methyltetrahydrofolate to homocysteine 

to give methionine. Recent studies have shown that the enzyme contains 

1 mol zinc/mol protein [I], and that the zinc cofactor is required for methyl transfer 

to the homocysteine substrate [2]. JTe have used EXAFS to characterize the 

zinc binding site in both the native and substrate bound forms of the zinc binding 

domain, hIetH(2-649). Changes observed in the XANES spectrum between the 

native and substrate bound LSetH(2-649) (Fig. 1) demonstrate that addition of 

homocysteine has a direct effect on the zinc binding s~te. Fourier transforms of the 

EXXFS (Fig. 2) clearly show an increase in amplitude of the first-shell scattering 

peak, in addition to a sniall shift to longer bond distance in the hIetH(2-649) + 

homocystcine sample. The EXAFS for the LIetH(2-649) were best moclelecl with 

l(N/O) at 2.03 A and 3S at 2.32 A, while the hIetH(2-649) + homocgsteine were 

best modeletl witti a single shell of 4s at 2.36 A [2]. Thesr results suggest that the 

homocysteine substrate binds directly to the zinc cofactor before methgl transfer 

occurs. 

[I] Goultling, C.W. antl RIatthews, R.G. Blochem, 1997, in press. [2] Peariso, K.. 

Goultl~ng. C.\V., Huang. S., ;\Iatthews, R.G., ancl Penner-Hahn, J.E., manuscript 

in preparation. 

Energy (eV) 

Figure 1. XXNES spectra of lSetH(2- 

649)with (dashed line) antl without 

(solid line)L-hornocgsteine. 

Supported in part by the NIH. GlI- 

38047(to JEPH) and GlI-24908 (to RGlI) 

Figure 2. Fourier transforms of MetH(2- 

619) with ancl without L-homocysteine.

I Temporal Speciation of Zinc in Zebrafish (Danio Riro) Embryos * I XgB I I X-Ray Absorption Spectroscopy of Nucleophilic Zn Enzymes I ~ 9J3 

K. Peariso, F. Su, J. Kuwada, J.E. Penner-Hahn (U. of Michigan) 

It has long been recognized that zinc plays a critical role in embryonic develop- 

ment, as evidenced by the teratogenic effects of zinc deficiency. Since the Zebrafish 

embryo develops without an influx of maternal nutrients, it must contain all of the 

zinc (and other necessary trace elements) required for development at the time of 

fertiliation. It has been shown that these embryos contain 1 mM zinc. XANES 

measurements have been made on five stages of Zebrafish embryos spanning the first 

eight hours after fertilization to determine whether changes ocurred in the bulk zinc 

environment during these early stages. Figure 1 shows the absorption differences 

between the XANES spectra of the later stages and the 1-cell, fertilized embryo. 

Based on these difference spectra, it is clear that there are significant changes in the 

bulk zinc environment of the zebrafish embryo during early development. Another 

intriguing result of these measurements is that the changes appear to be cyclic, 

demonstrating large differences in the 128-cell and 30% epiboly stages and very 

small differences in the high and 75% epiboly stages. Efforts are currently being 

focused on determining the type of zinc environment changes that could produce 

such differences and measuring the XANES spectrum of more stages within the first 

eight hours of development to verify the cyclic trend exhibited these measurements. 

\ / - 

MBT (high) 

h.ALA-- -A- 

Energy (eV) 

Figure 1. Time-dependent Zinc XANES spectra of developing Zebrafish embryos. 

Spectra shown are normalized absorption difference spectra relative to a 1-cell, 

fertilized egg. 

46 

CO 

-3 * Supported in part by the NIH, GM-38047 (to JEPH). 

J. Penner-Hahn and K. Peariso (U. of Michigan) 

Recent work has revealed the existence of a novel class of Zn enzymes, in which 

the Zn appears to function to activate a coordinated thiolate toward nucleophilic 

attack. X-ray absorption spectroscopy is being used to study three such enzymes 

that are involved in various aspects of methyl transfer: cobalamin-dependent and 

cobalamin-independent methionine synthase and cobamide: coenzyme M methyl 

transferase. EXAFS measurements on the native enzyme, on site directed mutants, 

and on enzyme samples with a variety of substrates and substrate analogs are in 

progress, with the goal of elucidating the three dimensional geometry of the Zn 

active sites. 

I

I 

CO 

cxl I Temporal Changes in Zn Speciation During Cell Development 

J. Penner-Hahn and K. Peariso (U. of Michigan) 

I X ~B I 

Zebrafish and Xenopus eggs contain ca. 1 mh4 Zn. Previous measurements have 

demonstrated that the Zn in these eggs undergoes reproducible, large changes in 

average structure as a function of time after fertilization. XANES measurements are 

being used to characterize these changes with improved temporal resolution. The 

data will be analyzed using the principal component method and selected temporal 

points will be used for EXAFS measurements. 

A Low Angle Diffraction Study of the Structure of the Actomyosin 

Complex; Effects of ADP Binding 

X9B 

K. Poole, hI. Lorenz, P. Ellison, G. Evans, G. Rosenbaum, P. Boesecke, K.C. 

Holmes, C.R. Cremo (Max Planck Inst.) 

With an atomic model for the actin filament (Holmes et.al. 1990, Nature, 347: 44- 

49; Lorenz et.al. 1995, J. Mol. Biol. 246, 108-119) and the atomic coordinates for 

at least one form of the myosin motor protein (Rayment et.al. 1993, Science261, 50- 

58) we are in a position to make use of high angle fibre diffraction data from myosin 

decorated actin filaments to refine a model structure of the complex. Nucleotide-free 

myosin subfragment-1 (S1) isolated from both chicken skeletal and smooth muscle 

sources was introduced into overstretched rabbit psoas muscle fibres. In both cases 

the protein binds tightly to actin and this results in the intensification of the actin 

based layer lines in the X-ray pattern. Refining an actornyosin atomic model against 

the nucleoticle-free skeletal S1 data produced a best fit which was similar to the 

model suggested by Rayment et.al. (1993) based on electron microscope evidence. 

ADP bintling had very little effect on the diffraction pattern. The nl~cleoticle-free 

smooth muscle S1 decorated filaments produced a very different diffraction pattern 

and the bintling of ADP was shown to induce a structural change in the heatl 

resulting in a pattern similar to that from skeletal S1 decorated fibres. The Ktl for 

ADP binding was shown to be ca. 2phI. It is most interesting that the two rigor 

conlplexes are strl~cturally different. If the rigor structure represents the end of the 

power stroke then the tlata imply that at least some part of the power stroke in 

thcse two motors is produced bv different configuration changes of the actomyosin 

complex. Alternatively, we rm~st cluestion our interpretation of the rigor structures 

themselves. \Ve are in the process of refining the model against the smooth muscle 

S1 tlata but it is clear that the ADP induced str11ctura1 change in the myosin 

heatl is very large and certainly involves the distal part of the heatl. Lye intend to 

continue our investigation of the actornyosin motor mechanism by looking at the 

bourrtl structures of myosin motors or parts of motors from different sources, both 

natural and engineered, with a range of nucleotitles or their analogues in the active 

site.

Escherichia Coli Primase Zinc Structure is Sensitive to the Binding 

of ATP and High Magnesium 

L.S. Powers and M.A. Griep (Utah State U.) 

X9B 

The structure of the single zinc site in primase from Escherichia coli was stud- 

ied using X-ray absorption (XAS). XAS provides information about the immediate 

sphere (radius about 5 A) of atoms surrounding the metal and has been widely 

used to characterize metalloproteins. The edge region of the spectrum provides 

information about the chemical identity of the ligating atom and their coordination 

geometry while the extended fine structure provides information about the number 

of ligating atoms and their average distance from the metal. The zinc site in native 

primase was found to be tetrahedrally ligated by three sulfurs at an average distance 

of 2.37 f 0.02 and one histidine nitrogen located at a distance of 2.11 to f 0.02. In 

the zinc site in high magnesium conformation of primase, one sulfur ligand is lost 

and one or two oxygen ligands are gained. Finally, when ATP was added to pri- 

mase, the zinc site structure was altered to octahedral coordination by three sulfur 

and three oxygen (or nitrogen) ligands, one of which could be a histidine nitrogen. 

These results and others indicate that the primase zinc site is similar to the PMPS- 

removable and nonessential-site zinc from Escherichia coli RNA polymerase which 

can also be coordinated by its initiating nucleotide ATP (Wu, F.Y.H., Huang, W.J., 

Sinclair, R.B., Powers, L. Journal of Biological Chemistry 267: 25560-25567, 1992. 

In light of this, the high-magnesium conformation result suggests that high mag- 

nesium primase becomes inactive because the zinc is prevented from coordinating 

ATP. 

EXAFS Studies of Nonheme Iron Enzymes 

L.Que, Jr., L.Shu, X.Wang, K.Chen, H.Hsu (U. of Minnesota) 

X9B 

Several metalloproteins containing nonheme diiron centers were investigated in 

the past year. They include methane monooxygenase (MMO), ribonucleotide reduc- 

tase (RNR), and purple acid phosphatase. A lot of efforts have been made to study 

the diiron structure of the high-valent reactive intermediate Q of MMO. XAS data 

analysis shows an unprecedentedly short Fe-Fe distance of ca. 2.46 angstroms [I]. 

A similar Fe-Fe distance of 2.46 angstroms has also been observed in intermediate 

X of RNR, another extensively studied diiron-containing enzyme [2]. These results 

prompt us to propose a Fe202 diamond core structure in both MMO and RNR 

catalytic cycle and therefore provide essential evidence for the proposed dioxygen 

activating mechanisms of nonheme diiron-containing enzymes. Data was also col- 

lected on an Fe(III)Zn(II) derivative of the purple acid phosphatase from porcine 

uterus which allows us to look at the Fe(II1) and the Zn(I1) sites separately. In 

the phosphate complex of this derivative, the observation of Fe-Zn and M-P (M = 

Fe, Zn) distances of 3.3 and 3.2 angstroms, respectively, indicates an FeZn(OR)2 

core structure and phosphate is proposed to bind to the metal center in a bridging 

mode [3]. Other oxoanions complexes, such as molybdate and tungstate, have been 

collected and analyzed as well, and an asymmetric bridging mode is proposed for 

FeZnUfMo04 and FeZnUfW04. The paper is in preparation. Because EXAFS anal- 

ysis can be a very useful tool for the structure characterization of unstable model 

complexes, we have also been using EXAFS to study model complexes related to 

intermediates of metalloproteins along with our investigation of metalloprotein sys- 

tems. In the past year, data was taken and analyzed on copper model complexes 

modeling the copper dioxygen chemistry in biological systems 141. It enabled us to 

reveal a novel reversible 0 -0 bond cleavage and formation by a dimetallic cluster. 

References 

[I] L. Shu, J. C. Nesheim, K. Kauffmann, E. MYnck, J. D. Lipscomb, and L. Que, 

Jr., "An Fe202 Diamond Core Structure for the Key Intermediate Q of Methane 

Monooxygenase", Science, 25, 515-518 (1997). 

[2] P. J. Riggs-Gelasco, L. Shu, S. Chen, D. Burdi, B. H. Huynh, L. Que, Jr., 

and J. Stubbe, "EXAFS Characterization of the Intermediate X Generated During 

the Assembly of the E. coli Ribonucleotide Reductase R2 Diferric-Tyrosyl Radical 

Cofactor", J. Am. Chem. Soc., submitted (1997). 

[3] X. Wang, C. R. Randall, and L. Que, Jr., "X-Ray Absorption Spectroscopic 

Studies of an FeZn Derivative of Uteroferrin" , Biochemistry, 35, 13946-13954 (1996). 

[4] S. Mahapatra, J. A. Halfen, E. C. Wilkinson, G. Pan, X. Wang, V. G. Young, 

Jr., C. J. Cramer, L. Que, Jr., and W. B. Tolman, "Structural, Spectroscopic, 

and Theoretical Characterization of Bis(m-oxo)dicopper Complexes, Novel Inter- 

mediates in Copper-Mediated Dioxygen Activation", J. Am. Chem. Soc., 118, 

11555-11574 (1996).

G 

3 I Metal Cluster Active Sites in Protein 

L. Que, Jr., L. Shu, X. Wang, K. Chen and S. Mandal (U. of Minnesota) 

I X ~B I 

Several metalloproteins containing nonheme-iron centers mere investigated in the 

past year. This class includes methane monooxygenase. ribonucleotide reductase, 

and purple acid phosphatase. We have collected and analyzed data on methane 

monooxygenase hydroxylase (hIhIOH). XAS analysis of AILSOH suggests the presence 

of two Fe-Fe distances of about 3aand 3.4& which are proposed to reflect two 

populations of hIhIOH molecules with either a bis (p-hydroxo) (p-carboxy1ato)- or a 

(p-hvdroxo) (p-carboxylato diiron(II1) core structure. respectively. This novel core 

flexibility is suggested to be required to accommodate the various intermediates in 

the catalytic cycle. A lot of efforts have been made to study the cliiron structure 

of the high-valent reactive intermediate Q of h1hIOH. XAS tlata analysis shows an 

unprecedentedly short Fe-Fc distance of ca. 2.46 it. A similar Fe-Fc distance of 

2.46 Ahas also been observed in intermediate X of ribonucleotide reductase (RNR), 

another extensively studies diiron-containing enzyme. These results prompt 11s to 

propose a Fez02 diamoncl core structure in both hIhIO antl RNR catalytic cycle 

and therefore provitle essential evidence for the proposed tlioxygen activating 

mechanis~ns of norheme iron-containing enzymes. Data was also collected on an 

Fe(III)Zn(II) derivative of the purple acid phosphatase from porcine uterus which 

allows 11s to look at the Fe(II1) a ~ the d Zn(I1) sites separately. In the phosphate 

complex of this derivative. the observation of Fe-Zn and 11-P (hI=Fe, Zn) distances 

of -3.3 antl 3.2 A, respectively. indicates an FeZn(OR)2 core structure and phosphate 

is proposed to bind to the nletal center in a britlging mode. Other oxoanions 

corr~plexcs, s ~~ch as rnolyhtlate autl tungstate, have been collected antl analyzed as 

well. ;mtl an asyrnnletric bridging mode is proposed for FeZnUfoWO.~. The paper 

is preparation. Because EXAFS analysis can he a very useful tool for the structure 

tlctcrmination of unstable rnotlrl complexes, we haw also been using EXAFS 

to st~~cly n~oclel complexes related to interrnetliates of ~netalloproteir~s along with 

our irwestigation of metalloprotein systems. In the past year, tlata mas taken antl 

analyzed on copper nlotlel coruplcxcs ~notleling the copper tlioxygen chcrrlistry in 

biological s,vstenls. 

I Thermopphillic Alcohol Dehydrogenases I X ~B I 

I. Sagi (Weizmann Institute of Science) 

Interconversion of alcohols, aldehydes, and ketones are essential processes in both 

prokaryotes and karyotes. The oxidoreductases catalyzing these reactions use a va- 

riety of different electron acceptors and can be ivided into three main groups: 1) 

the NAD(P)-dependent alcohol dehydrogenases 2) the NAD(P)-independent alcc- 

hol dehydrogenases, which use other cofactors for catalysis; and 3. FAD-dependent 

alcohol oxidases. which catalyze irreversible oxidation of alcohols. Thermoanaer- 

obacter (formerly Thermoanaerobium) brockii alcohol dehydrogenase (TBADH) is a 

medium chain, NADP-linked. class A enzyme that reversibly catalyses the oxitlatiorl 

of secondary alcohols to the corresponding ketones. 

TBADH 

RC(OH)R1 + NADP RC(0)Rf + NADPH 

The ubiquitous alcohol clehydrogenases (ADHs) are found not only in bacteria, 

but also in yeast, plants, insects and in man. ADH is an oxidorcductase, requiring 

either NAD(H) or NADP(H) as a coenzyme, that reacts with primary and secondary, 

lincar and branched-ctiain, aliphatic and aromatic alcohols and with their 

orresponding aldehydes antl ketor~es. Althollgh some ADHs clepcnd on iron for activation 

and certain ADHs are known to be rnetal-free, rnost ADHs contain zinc at 

the active site. Zinc-dependent ADHs are either tlirners, us~lnlly found in higher 

plants and mammals, or tetrarriers, s~lctl as those present in yeast and bacteria. A 

rrior~onleric ADH was isolated from Sacch,nromyces cerevisine, but its ~netal content 

is yet unknown. 

a) Native TBADH. XAFS tlata of native TBADH has been collected on zinc 

and cobalt K-edges. Xrlalysis of EXr\FS antl edge tlata of native enzyme and its 

metal tlerivatives will provide the grolmd base for the assigur~~ent of coordination 

eriviror~n~ent antl accurate rnetal-ligand distances at t,he active site. b) Inhibition 

Studies. XAFS rneas~~rerrier~ts on inhibited TBADH were contl~~ctetl using 

TB.IDH-DhISO (dimethyl sulfoxitie) cornplcx. DhISO is know11 to inhibit ALDH 

in a transition state manner. X-ray crystallography studies of ALDH-DAIS0 complexes 

show that the DAIS0 ligantl is directly bound to the catalytic zinc ion. XAFS 

and edge tlata will be collected on native TBADH a~ltl Ctl/Co substitutctl TBXDH 

cornplexetl with DLISO. -Issigning the coordination environment and r~~etal-liga~ltl 

tlistances of the active site in TBADH-DSISO complex will provide the struct~~re of 

the transition state analogur of TBXDH antl a relevant structural irltertnetli~te in 

the catalytic pathway.

EXAFS of the Low Spin Ferric Center of Nitrile Hydratase 1 X9B 

R.C. Scarrow, B. Strickler, D. Pringle (Haverford College) and M. Nelson (DuPont) 

We have been continuing our investigations of the low spin iron center in nitrile 

hydratase, in collaboration with Mark Nelson and John Cummings of DuPont, who 

have provided us with frozen protein samples. EXAFS has identified two or three 

sulfur ligands to the iron center, with the remaining ligands being oxygen or ni- 

trogen scatterers. Some minor changes are seen with binding of inhibitors (to the 

enzyme-not necessarily to the iron center) such as phenylhydrazine or isobutyroni- 

trile. We are currently in the process of modelling the EXAFS to give bond length 

distributions to see if this may give insight into the changes which are occuring 

on the binding of these inhibitors. We have also obtained EXAFS data on model 

low spin ferric compounds prepared by Henry Jackson and Prof. Julia Kovacs of 

the Department of Chemistry, University of Washington. These complexes have a 

ligand with a N3S2 donor set and can be prepared as a binary low spin iron (111) 

complex (a rare example of five-coordinate iron (111) or as ternary, six-coordinate 

complexes with a variety of auxilliary ligands including azide and nitric oxide. The 

EXAFS and edge intensities of these complexes are being compared to those of 

nitrile hydratase to gain further insight into the coordination of iron in the enzyme. 

amin Enzymes 

of XAS Data: Structure of the Active Site of Cobal- 

E. Scheuring, M. Chance (AECOM), R. Banerjee, and R. Padmakumar (U. of 

Nebraska) 

The two available crystallographic structures of cobalamin dependent enzymes, 

the 27 kDa fragment of the methylcobalamin-dependent enzyme, methionine syn- 

thase, from Escherichia coli [C. L. Drennan et al. Science, 266, 1669 (1994)l and 

the 5'-deoxyadenosylcobalamin-dependent enzyme methylmalonyl-coenzyme A mu- 

tase from Propionibacterium shermanii [F. Mancia et al. Structure,4, 339 (1996)], 

show striking similarities despite the differences in reaction mechanism. In partic- 

ular, the 5,6-dimethylbenzimidazole group is detached and replaced by a histidine 

group of the enzyme. Here we present an analysis of Extended X-ray Absorption 

Fine Structure (EXAFS) spectroscopic data for both 5'-deoxyadenosylcobalamin 

and aquocobalamin bound to methylmalonyl-coenzyme A mutase in the absence of 

substrate. The analysis is conducted with a suite of programs called AUTOFIT 1.0 

[Chance et al., Biochemistry, 1996, 35, 90141, which allows an evenhanded com- 

parison of the goodness-of-fit of the EXAFS data to a varied grid of simulations 

based on the ab initio EXAFS code FEFF 6.01. The x-ray edge data indicate 

an increase in effective nuclear charge of the metal ion of the enzyme bound 5'- 

deoxyadeonsylcobalamin compared to the corresponding free cobalamin and the 

EXAFS results show small decreases in equatorial and no significant change in the 

Co-C bond length (despite the potential elongation of the Co-N(His) bond) upon 

cofactor binding to the enzyme. Thus, the change in coordination of the nitroge- 

nous axial ligand engineered by the enzyme does not significantly contribute to a 

trans effect in the ground state. Weakening of the Co-C bond must be initiated by 

substrate binding. In addition, the global mapping technique resolves discrepancies 

between previous EXAFS results and crystallographic data on aquocobalamin.

4j 

CD 

t3 I Structure and Thermally Induced Failure of Organic LEDs * 1 XlOB 1 

P. Fenter, F. Schreiber, V. BuloviC and S. R. Forrest (Princeton Univ.) 

Figure 1. 

* This work is supported by the NSF, the .IFOSR, and the Universal Display Corpora- 

tion. F. S. acknowledges the support of the DFG. 

Surface X-ray Diffraction Studies of Monolayers of w-alkenethiol on 

Au(ll1) * 

Organic light emitting devices (OLED) represent a new basis for light emissive flat T.Y.B. Leung, P.Fenter, F.Schreiber, P.Eisenberger and G.Scoles (Princeton U.) 

panel displays. IVe have used x-ray reflectivity to study the structure and thermal 

degradation mechanism of films and heterostructures consisting of the archetype 

molecular OLED materials, "TPD", and "Alq3" which were grown on Si wafers by 

thermal evaporation under high vacuum 11. The x-ray specular reflectivity of three 

thin film structures is shown in Fig. 1 t thin and bold lines are experimental data 

and theoretical fits, respectively). These include (i) TPD on Si, (ii) Alq3 on Si. 

ancl (iii) .41q3/TPD on Si. The derived the electron density profiles (shown in Fig. 

lb), reveal interface roughnesses of

In-situ Studies of the Growth of Coassembled Surfactant/Silica 

Films 

L. Zhou, P. Fenter, I. Aksay, P. Eisenberger (Princeton U.) 

XIOB 

Mesoscopic surfactant/silica thin films have been grown on the surface of mica 

and silicon under the aqueous condition at pH = 1.6. The molar ratio of the growth 

solution is TEOS : CTAC : Hz0 = 1:2:1000. The structure and the lattice strain 

of the thin film have been studied [I]. The in-situ growth of the film is studied by 

following the specular diffraction in real time. 

Our results show that there is a 7 hour induction time and the film grows to 1 

micron in a few hours after nucleation with a nonlinear growth rate 121. Similar 

growth behavior has been found for the films grown on silicon substrate. Therefore 

the induction time is independent of the nature of the substrate. 

We have changed the concentration of CTAC and TEOS to investigate the role 

that each component plays in the growth process. We have found that the induction 

time is inversely proportional to the TEOS concentration, and there are at least two 

growth regimes. At high surfactant concentrations, the induction time depends on 

the ratio of TEOS to CTAC concentrations. At low surfactant concentrations, the 

induction time depends on the concentration of TEOS only. The induction time is 

correlated to the growth rate of the film. 

These data suggest that the film growth is a true coassembly process in which the 

polymerization rate of the silicate, the formation of the surfactant micelles and the 

interaction between the growth solution and the substrate all play a very important 

role. 

[I] I. A. Aksay, M. Trau, S. Manne, I. Homma, N. Yao, L. Zhou, P. Fenter, P. M. 

Eisenberger, S. M. Gruner, Science, 273, 892-897 (1996) 

[2] L. ZHou, P. Fenter, I. A. Aksay and P. M. Eisenberger, The 43rd National 

Symposium of American Vacuum Society, October 1996 

Local Structure of DiluteTernary 3d Transition Metal Dopants in 

Ni3A1 * 

XllA 

M. Balasubramanian, R. Lyver, J. I. Budnick and D. M. Pease (U. of Connecticut) 

We have utilized the technique of XAFS to study the local structural order 

of 3d transition metal (TM) ternary dopants (Ti, V, Cr, Mn, Fe and Co) in 

Ni75TMXA125-,. In - NisA1, the first shell around A1 consists of 12 Ni atoms. 

Ni is surrounded by 8 Ni and 4 A1 atoms. In all cases dopant K-edge XAFS results 

show only Ni backscattering contribution in the first peak of the Fourier transform. 

A1 backscattering contribution is either completely absent or is so weak that it is 

masked by the strong dopant-Ni bond [I]. The number of Ni near neighbors sug- 

gests that for Ti, V, Cr, Mn and Fe absorbers, a majority of the dopants occupy 

the A1 sublattice. However, even in the case of Co dopants where studies by others 

indicate that the Co atoms occupy the Ni sublattice, no A1 backscattering contri- 

bution can be detected. A model [2] based on a highly distorted A1 sublattice, 

created by dopant atoms occupying the Ni sublattice, gives a possible explanation 

for the absence of A1 backscattering contributions, and furnishes an explanation for 

similar studies by others in ternary doped - Nz3A1. These investigations are of 

importance in understanding the effect of dopants on the mechanical properties of 

such alloys. 

ill M. Balasubramanian. R. Lvver. " , J. Budnick and D. Pease, J. de Phvsiaue 7. 

" A , 

ci-1'043 (1997) 

[2] M. Balasubramanian, R. Lyver, J. Budnick and D.Pease, Appl. Phys. Lett. 

71(3), 330 (1997) 

* Work supported by the U.S. DOE under Grant No. DE-FG05-89-ER45384.

I 

C3 

rp I Preferential Co-Si bonding at the Co/SiGe(100) interface * I X11A [ 

B. Boyanov, P. Goeller, D. Sayers: and R. Nemanich (NCSU) 

The initial stages of the reaction of Co with Sio.7gGeo.21(100) were studied in 

situ with extended x-ray absorption fine structure spectroscopy (EXAFS) and reflection 

high energy electron diffraction (RHEED). The first coordination shell of 

as-deposited 0.7 monolayer (AIL) Co films consisted of Si and Ge atoms in approximately 

41 ratio, similar to the stoichiometry of the Sio.7gGeo.21 substrate. After 

annealing at 450 "C the 0.7 AIL film assumed a CoSia-like structure (Fig. 1) with 

6-fold CwSi first-shell coordination and a (3fi x fi) surface reconstruction. Similarly 

annealed 1.7 AIL films exhibited a CoSiz structure with the same reconstruction 

and 8-fold Cc-Si coordination. Residlial Co-Ge bonding (= 1 nearest neighbor) was 

detected in both the 0.7 and 1.7 AIL annealed films. The deviation of the Si:Ge ratio 

in the first coordination shell of Co from that of the Sio.7~Ge0.21 substrate indicates 

referential formation of Cc-Si bonds in the annclactl films. The observed vreferential 

CwSi bonding has significant implications for the growth of single-crystal CoSia 

template lavers on SiGe. Such template layrs have been witlely used to control the 

formation of misoriented grains in ?pitaxial CoSiz/Si(100) hcterostructl~rcs. 

0.7 ML 

annealed 

(1 0.7 ML 

as depositec 

anne led 

1 \wxdLj 

0.7 ML 

annealed 

0.0 1.0 2.0 3.0 4.0 5.0 6.0 

Radial distance (A) 

I Co-deposition of Cobalt Disilicide on Silicon-Germanium Thin Films I XllA I 

P. Goeller (No. Carolina State U.) 

Figure 1. Sormalized and Fourier-transformed k"weighted EX4FS data (solid line) 

0 2 4 6 8 

and fit results (dashed line) for the sarnples used in this study. The top trace is the 

R( 

data for a 730 =\-thick CoSiz/Si(100) film. Figure 1. Fourier transforms of k2- 

= This work was supported by DOE grants DE-FG03-93ER79236 and DEFGO5- 

89ER-lS38-l. 

weighted EX.-\FS data for direct deposited 

samples annealed at 500-800 C 

for 10 mi1lutes. 

The formation of CoSia on strained epitaxial Sio.sGeo.2/Si(100) films has been 

studied as a function of the depositoin method and annealing temperature. TITO 

types of deposition processes were used: a direct method, where 5 nm of pure Co 

metal were deposited at room temperature onto a strained 80 nm thick Sio.sGeo.2 

layer; and a co-deposition method, where 5 nm Co and 18.2 nm Si were simulta- 

neously deposited in a 1:2 ratio onto a strained Sio.sGeo.2 layer at 450 C. Samples 

mere then annealed at temperatures ranging from 500 to 800 C. EXAFS and XRD 

mere used to characterize the structure of the resulting films. It tvs found that 

the samples prepared via the direct tlepositon method did not convert to CoSiz 

at any annealing temperature up to 800 C, while the cc-deposited samples formed 

epitaxial CoSin at even the lowest annealing temperature of 500 C. These results 

are discussed in terms of proposed reaction rnechanisrns of the different deposition 

rnethotls, based on consideration of the Co-Si-Ge ternary phase diagram. 

Figure 2. Fourier transforms of k2- 

weighted EX.4FS data for cc-deposited 

samples annealed at 500-700 C for 10 

minutes.

p 

01 

Stability of Heavy-Metal Sulfides During Oxidation of Contaminated 

Soil from a Superfund Site 

P. D. Hansen, D. Hesterberg, W. Zhou, and D. E. Sayers (NC State) 

XllA 

The long-term stability of solid-phase heavy-metal species in soils depend on their 

resistance to changes in the soil chemical environment. The objective of this study 

was to determine how exposure to oxidizing conditions affected the speciation of 

Cu, Zn, and Pb contaminants in samples of reduced soil from a superfund site in the 

eastern coastal plain of North Carolina. EXAFS analyses of Cu, Zn, and Pb were 

done at Beamline X-11A on preserved samples collected from four depth intervals 

(zones) in the soil profile of a waste-disposal site at the Marine Corps Air Station 

in Cherry Point, NC. Subsamples of this soil were used in a column-flow study 

to measure metal dissolution under changing redox conditions. After 1 month of 

continuous exposure to aerated aqueous solution, the soil columns were dismantled 

and analyzed using EXAFS spectroscopy. The samples contained 1,100 to 1,800 

mg Cu/kg, 4,300 to 11,000 mg Zn/kg, and 1,700 to 4,100 mg Pb/kg. EXAFS data 

showed that metals in the soil samples from Zone 1 (0 to 20 cm depth) and Zone 

2 (23 to 47 cm) were predominantly bonded to oxygen in the first shell (Cu-0, 

Zn-0, and Pb-0 bonding). In the Zone 3 (47 to 73 cm) and Zone 4 (73 to 101 

cm; the shallow groundwater zone), there was evidence for metal-sulfides for all 

three metals, with CuS being the dominant Cu phase (Fig. 1). After the column 

treatment with oxygenated CaC12 solution, the proportion of metal-sulfides was 

essentially unchanged, indicating that these minerals were resistant to oxidative 

dissolution during the course of the column study. A loss of acid volatile sulfide 

(sulfides converted to hydrogen sulfide gas by an acid treatment) during the column 

experiment may have helped to stabilize the heavy-metal sulfides, despite the redox 

potential increasing from -200 to +50 mV (at pH 7.5). The results indicate that 

the metal sulfides in the deeper zones of the contaminated soil would be resistant 

to dissolution during short periods of increased redox potential. 

Figure 1. Fig. 1. Radial structure functions (uncorrected for phase shift) of Cu in 

samples from different depths (zone 1 is shallowest) in the soil profile at the Marine 

Corps Air Station superfund site. 

XAFS Study of Copper Binding with a Sulfur-Rich Humic Acid / XllA 

D. Hesterberg, D. E. Sayers, W. Zhou, and K. Hutchison (NC State U.) 

The geochemical transformation of heavy metal contaminants into unique min- 

eral phases and adsorbed chemical species in different soil environments is critically 

important for understanding the long-term stability and fate of these contaminants. 

Past studies showed that with increasing concentration of certain transition metals 

bound to soil humic acid (HA), the metal binding affinity decreased. Humic acid is 

a purified extract of organic matter that typically contains an abundance of reactive 

carboxylic and phenolic acid functional groups and lesser amounts of nitrogen (e.g., 

amine) and sulfur (e.g., thiol) groups. The objective of this research was to deter- 

mine whether Cu(I1) preferentially binds to sulfur groups in HA at low adsorbed 

metal concentrations. A sulfur-rich HA extracted from a soil in a coastal marine 

wetland was reacted with Cu(I1) at pH 5.6 in aqueous background solutions of 0.1 

M NaCl or 0.1 M NaN03. The molar ratio of organic S-to-metal was 4.25, and the 

total Cu concentration in the suspension was 2 mmol/kg. Sulfur K-XANES data 

from NSLS Beamline X-19A indicated that about half of the organic sulfur in the 

samples was in a reduced oxidation state (-11). Copper K-EXAFS spectra showed 

no evidence for first-shell Cu-S bonding, but Cu bonding was primarily to oxygen 

or nitrogen atoms. Despite the chalcophilic nature of Cu(II), it does not appear to 

preferentially bind to organic S groups under the experimental conditions used. This 

result suggests that our past observations of Cu-S bonding in samples of reduced soil 

collected from contaminated sites primarily represents inorganic Cu-sulfide species.

?j 

(3 

c, 

XAFS Study of Metal-Sulfide Formation in Contaminated Soil 

XllA 

Treated with H2S 

D. Hesterberg (NC State U.), E. C. Thornton (Pacific Northwest National Lab) : 

SIT. Zhou, and D. E. Sayers (NC State U.) 

The sequestering of potentially-toxic heaw metals as insoluble sulfide minerals 

under reduced soil conditions may reduce metal mobility and bioavailability. The 

objective of this study was to determine whether injection of dilute HzS(g) into a 

contaminated soil induced the formation of Cu- and Pb-sulfide minerals. The H2S(g) 

remediation treatment was originally designed to reduce Cr(V1) to Cr(II1) in soil; 

however, sequestering of heavy metals as sulfides may also be beneficial in certain 

soils. A colunln of soil material from the Chemical SS7aste Landfill at Sandia National 

Laboratory was treated in the laboratory with a mixture of 0.01% (v/v) H2S(g) in 

Na(g). The sample contained 20 nlnlol Cu/kg, 18G mmol Pb/kg, antl 208 mmol 

Fe/kg. XAFS analyses were done at Beamline X-11A on untreated and treated 

soil samples to determine changes in local molecular bonding of Cu(II), Pb(II), and 

Fe(II1) induced by the treatment. Copper(I1) was converted from a predominantly 

1st-shell oxygen-bonded solid phase to CuS. Although the sanlple contained considerably 

more Pb(I1) and Fe(III), the H2S(g) treatment had no discernible effect 

on the 1st-shell Pb-0 and Fe(II1)-0 bonding structures of these metals. Results 

were consistent with the greater thermotlynarnic stability of CuS relative to PbS 

and FeS. This stlltly demonstrates the utility of XAFS for evalt~ating the sllccess of 

in-situ renletliation treatnlents tlesignetl to chemically alter rontaminant,s in place. 

Electrocatalysis of Methanol and CO Oxidation: An In situ XAS 

1 1 XllA 1 

Study * 

S. Mukerjee and J. h'lcBreen (BNL) 

Elements such as Ru and Sn used as ad-atoms or as alloying elements are known to 

enhance methanol and CO oxidation. Unlike Ru, enhancement due to Sn additions 

depend on the nature of interaction of Sn with Pt. Pt alloyecl with Sn is marginally 

active for methanol oxidation in contrast to upcl Sn ad-atoms on Pt, but show 

good activity for CO oxidation. In situ XAS studies at the Pt L3 edge for Pt/C 

shows that adsorption of hydrogen, oxygenated species and methanol oxydation 

products (CO and CHO poisons) induce major changes in the Pt L edge XAS. 

This is evident from the changes in the white line in at 0.0, 0.54 and 0.84 V in 

the presence of 1 hI HC1O.t + 0.3 hI hIeOH. (see J. Electrochem. Soc.,143, 2285 

(1996) antl J. Electroanal. Chem (In Press) for more details. In contrast to this 

the Pt Lg etlge white line for PtRu/C and PtSn/C show very little variation with 

potential. Alloying of Ru and Sn to Pt however have very different effects on their 

electronic and geometric characteristics. In the case of Ru a increased white line 

(higher Pt d band vacancy) and shorter Pt-Pt bond distance is affected in contrast 

to alloying with Sn. XANES at the Sn antl Ru K edges in PtRu/C anti PtSn/C 

alloys as well as uptl Sn on Pt/C however provide clear evitlence of the presence 

of oxygenated species even at 0.0 V. The strength and nature of these species are 

ho\vever potential dependent. For upd Sn on Pt/C, the XANES at the Pt La etlge in 

I 11 FICIO.1 shows behavior similar to those observed previouslv in the case of Pt/C 

(see ref. I), a congruence of white lines for sample and Pt reference foil at 0.54 V 

(double layer region). This together with the EXAFS results indicate that uptl Sn 

does not signiticantlv eKect the electronic antl structural charaterist,ics of Pt. Thc 

higher Pt d band vacancy, shorter Pt-Pt bond distances in the PtRu/C together 

with the presrnre of oxygenated species on RII help explain the higher activity for 

methanol and CO oxitlation. The opposite effects on Pt in PtSn alloy help explain 

its lack of AIeOH activity. In the case of uptl Sn the Pt remains rlnaffected, that 

together with the presence of oxygenated species on Sn ad-atoms at lower potentials 

hclp cxplain the enhanced methanol oxidation activity. 

This n-ork was supported by the Office of Transportation Technologies. Electric and 

Hybrid vehicles division of L-. S. D. 0. E

An XAS Study of Corrosion Characteristics in AB5Type Metal Hy- 

XllA 

dride Electrodes * 

S. Mukerjee, J. McBreen, J. J. Reilly, J.R. Johnson and G.D. Adzic (BNL) 

The cycle life characteristics of AB5 alloys depend primarily on the extent of its 

susceptibility to stress cracking due to volume expansion and contraction during 

hydriding. However, several alloy substituents such as Ce, Co etc., and presence of 

zincate in the electrolyte helps improve cycle life without having a direct correlation 

with changes in volume expansion/cycle. This investigation is aimed at correlating 

the structural and cycle life characteritics of various AB5 type alloys with the corrosion 

of constituent elements in these alloys such as Ni, Co, Mn and Fe. The focus 

however has been on the Ni due to its relative abundance and catalytic importance 

in the alloy. Surface (electron yield) and bulk averaged (transmission) XAS were 

conducted on the electrodes before and after electochemical cycling (150 cycles). 

The powders used as a part of this study were peractivated in the gas phase to 

ensure particle sizes 2-5 micro-meters. The electron yield mode probed the first 

200-250 angstroms of the surface based on the more energetic KLL Auger electrons 

with 6.5 KeV electrons at the Ni K edge. 

EFFECT OF Ce SUBSTITUTION 

Ce substitiution in the A component of the prototype LaNis alloy results in 

reduction of corrosion of the substituent elements such as Ni and hence in lower 

build up of surface Ni(OH)2. This was evidenced from comparison of the white 

lines of the Ni K edge XAS in the transmission mode for electrode as a function 

of cycling. Comparison of the electron yield and transmission spectra at the Ni 

K edge after 150 cycles for sample with and without Ce showed very little surface 

build up of Ni(0H)z in the Ce containing sample in contrast to those without Ce 

substitution. Independent measurements using in situ scanning vibrating electrode 

technique have shown that Ce passivates the surface reducing surface corrosion. 

EFFECT OF Co SUBSTITUTION 

Co substitution causes lowering of the molar volume of hydrogen and hence a 

reduction in stress cracking of the alloy. The Co K edge XANES in the electron 

yield and transmission modes have also revealed a build up of the more conducting 

- - 

Co(OH'l7 on the surface of the electrode neaatine: the effects of resistive build uu of 

suriace 'fii(0~)Z. 

EFFECT OF ZINCATE CONTAINING ELECTROLYTE 

The presence of ZnO in the electrolyte results in significant imporovement of the 

cycle life in non Ce substituted samples. This translates itself to lower Ni corrosion 

and build up of Ni(OH)2 in these samples as evidenced from the electron yield 

and transmission XANES. In the Ce substituted samples the effect is marginal and 

agrees with significantly smaller increases in the cycle life. 

!d 

a 

-J * Office of Basic Energy Sciences, U.S.D.O.E. 

I Local Structure of Br in Brominated-YBCO * I XllA I 

D. Potrepka, M. Balasubramanian, J. Budnick and D. Fenner (U. of Connecticut) 

Bromination of deoxygenated YBCO leads to a partial restoration of supercon- 

ductivity and causes the YBCO lattice to change from a non-superconducting te- 

tragonal structure to an orthorhombic structure [1,2]. In order to understand the 

mechanism by which superconductivity is restored in these materials it is of inter- 

est to understand the local structural properties of Br atoms in the YBCO lattice. 

Neutron diffraction measurements suggest that Br atoms occupy vacant O(4) sites 

in the YBCO lattice [2]. Unfortunately, these experiments are hampered by the 

similarity in the neutron scattering lengths of oxygen and Br. We have performed 

low-temperature (11 K) Br K-edge XAFS measurements in brominated-YBCO and 

find that Br does not occupy the YBCO lattice but rather precipitates out as small 

BaBrz-like particles. In conjunction with Cu NQR measurements our results indi- 

cate that on bromination the system undergoes an oxygen redistribution within the 

YBCO lattice. This redistribution probably causes the restoration of superconduc- 

tivity in these materials [3]. 

H. B. Radousky et al., Phys. Rev. B 41, 11140 1990 

M. Mokhtari et al., Solid State Comm. 93, 48'7 [lS95] 

D. Potrepka et al., to be submitted to Appl. Phys. Lett. 

Figure 1. Comparison of the Br- XAFS spectra of brominated YBCO with BaBrz. 

The similarity in the XAFS clearly reveals the presence of small particles of BaBr2 

in brominated-YBCO. 

* Work supported by the U. S. DOE under Grant No. DE-FG05-89-ER45384.

(3 

m 

Local Coordination of Ba and Pb in Calcite from XAFS Spec- 

troscopy 

R. J. Reeder (SUNY at Stony Brook) and G.M. Lamble (LBNL) 

XllA 

XAFS spectra at the Pb L(II1)-edge and the Ba K-edge of Pb- and Ba-doped 

calcite (CaC03) were analyzed to reveal that Pb(I1) antl Ba(I1) both substitute 

for Ca in the unique octahedral metal site in the corner-shared calcite structure. 

First-shell Pb-0 and Ba-0 distances are very similar to those predicted for sixfold 

coordination, however, sixfold coordination for both ions is considered rare because 

of their large sizes and preference for higher coordination mtmber. For example. 

PbC03 and BaC03 both have the aragonite structure. in which the metal is ninefold 

coordinated. Fits for higher shells irlclicate that the local environment is significantly 

distorted around the Ph(I1) antl Ba(I1) octahedra in the calcite. The dilation of the 

local structure is proportional to their ionic radii, but Pb-Ca and Ba-Ca distances 

indicate that the dilation is also highly localized, ancl rnost likely accommodated by 

rotation of rigid structural units. 

Previolw work has stlown that Pb and Ba impurities are incorporated differentially 

between surface sites that are structl~rally distinct because of the position and 

orientation at which they are exposed on growth surfaces of calcit,e. The present 

observations tlernonstrate that despite differences in surface site preferences these 

large impurity species occupv a unique site in the bulk. The distortion associated 

with the incorporated metals may affect the stability (and sohtbility) of the solid in 

the natural environment. 

Kinetics and Mechanisms of Trace Metal Sorption at the Min- 1 XllA / 

eral/MTater Interface: A Time-Resolved Study 

A. M. Scheidegger, D. R. Roberts, D. G. Strawn and D. L. Sparks (U. of Delaware) 

A thorough understanding of the kinetics and mechanisms of metal sorption on 

soil mineral surfaces is critical in determining the fate. mobility, speciation and 

bioavailability of metals in aqueous and soil environments. XAFS spectroscopy was 

used to monitor changes in the local structural environment of Ni ancl Pb sorbed on 

clay minerals, metal oxides, ancl the clay fraction of a soil with increasing reaction 

time. 

XAFS data analysis revealed the appearance of multinuclear Ni complexes in the 

Ni/pyrophyllite and Nilgibbsite systems, as shown by the second peak representing 

the second Ni coordination shell at R =: 2.8A in the radial structure functions (Fig. 

la,h), after a reaction time of minutes and hours. These results suggest that adsorption 

and nl~cleation processes (mixed Ni/AI hydroxide phase formation) can occur 

simultaneously over time scales of onlv minutes. As reaction time progressed. the 

number of second neighbor Ni atoms (N.v~-N~) at a distance of -- 3.051\ incrcasccl 

(N~,-N, = 1.7-5.1 for Ni/pyrophyllite and Ni~,-.y, = 1.5-5.5 for Ni/gibbsitc). 

\Vith montrnorillonite, a mixed Nilill hydroxide phase did not form until after 

48 h and the pl~ase continued to grow with increasing reaction time. illtholtgh 

rtot shown, mixed cation hydroxide phases also occurred on the soil clay si~rface 

in min~~tes. With Ni. our study suggests that three phenomena occur at the rnineral/liquitl 

interface: (1) non specific (i.e.. ol~tcr-sphere complexation) and/or specific 

adsorption (i.e., inner-sphere complexation), (2) tlissolutiorl of 111. (perhaps the 

rate-limiting step) and (3) mlcleation of a mixed Ni/Al phase. 

\fTliilc Pb sorption on mineral surfaces resltlts in similar tir~te-tlcpcndent behavior. 

the retention mechanisms are different. Slow t~l~cleat,iorl reactions can be rllletl oi~t 

because analysis of the radial structm-e fimctior~ (Fig. 2) does not exhibit any major 

features (e.g., second peaks indicative of secorltl shell neighbors) beyo~ld the primi~ry 

Pb-0 structltral peak at ~1.Rtl (~~ncorrectetl for phase shifts) with long incubation 

times (Fig. 2). The biphasic sorption behavior ol)scrvetl with Ph rnay be related to 

retention on sites of variable reactivity and/or tliffitsion limited sorption. 

! q 

2 , 

ll Houn 

3 3 1 5 5 . - 3 " 

R (A) 

Fizure 1. RSF of a) Si/~vro~hvllite 

,'. . . and 

b)"~i/gibhsite. he reaction conditions Figre 

RSF for Pb sorbed on 9--A1201 

were: pH = 7.5: [Xi], = 3 m.11 I = 0.1 

incubated for 24 hours to TO days. Re- 

31. 

action conclitions were: DH = 6.5: IPbl,

CL 

3 

3 

A Tunable LauelBent-Laue Monochromator with Fixed Second 

Crystal for Synchrotron Radiation * 

X12A 

Z. Zhong, G. Le Duc (NSLS), D. Chapman (CSRRI, IIT), and W. Thomlinson 

(NSLS) 

A Laue/bent-Laue two crystal monochromator has been developed for producing 

a monochromatic x-ray fan beam with energy tunable over a wide range by adjusting 

the angle of only the first flat Laue crystal. Bending the second crystal increases 

the feflection bandwidth. making the the monochromator very stable against vibrations. 

The monochromator was tuned to above and below the K edge of indium 

at the X12A beamline at the National Synchrotron Light Source for dual energy 

subtraction imaging. 

The principle for the tunable monochromator is shown in Fig.1. The two crystals 

are in non-dispersive geometry. The second crystal is strongly bent cvlintlricallv 

with bending radius p? in the order of one meter. When the distance s between 

the crystals is chosen to satisfy: s = cos(y QRO), the beam will he reflected by 

the second crystal for a wide range of energy defined by the Bragg angle of the first 

crystal. Thus tuning of beam energy can be achieved by acl.justment of the first 

crystal. 

With the first crystal tuned to reflect a beam of 27.94 keV, the angle of the second 

crystal was scanued, Fig.2 shows the rocking curves obtained this way for different 

beam vertical heights. It is seen that for heam vertical sizes less than 0.6 mrn, there 

exists a flat plateau in the rocking curves. The width , of the plateau is a good 

indicator of how stable the nmnochrornator is against vibration. A simple n~odel 

was proposctl which gives = (LIT- At)/, wtiert: L17 is the F\VHRI of the bent-crystal 

reflectivity curve arid AQ = DCo5,~T,,r,. Agrccmcnt with experiment is excellent. 

, .. ., 

In concl~~sion, a novel monochromator was conceived antl tested. Good features 

inclutle: Tuning of energy by one crystal antl stability. Limit,ations inclutle: the 

beam height can not cxceed about 0.5 rnnl antl a reHectivity of about 0.3 for the 

second crystal. 

---...-- 

Rowland Circle 

,r,_ 

0: (rnradmn) 

Figure 1. Design considerations 

Fimre 2. Rocking curves obtained with 

L, " 

vertical beam heights of 0.1. 0.2. 0.3. 0.4. 

work supported by US DOE DE-AC02- 

0.6 anti 0.8 

76CH00016 

The Structure Determination of Murine Cytosolic Epoxide Hydro- 

I lase 

hI. Argiriadi and D. Christianson (U. of Pennsylvania) 

X12B 

Cytosolic epoxide hydrolase's primary function is proposed to be the the hydrol-ytic 

cleavage of epoxides to yield vicinal trans diols in the liver cells. This 

is a critical mammalian detoxification mechanism. eg.. epoxides might otherwise 

modify protein and/or DNA targets in the cell. They also play a role in the formation 

or degradation of endogenous chemical mediators. A structure determination 

of this enzyme might render a better understanding of how particular toxins are 

metabolized and possibly how cytosolic epoxitle hyclrolase maintains steady state 

levels of physiological mediators. Several trips were niatle to the Brookhaven synchroton. 

During these trips. native cytosolic epoxide hyclrolase crystals mere tested 

which diffracted to 2.8 A with Rsyms of 6.0%. In comparison, data collected at 

the University of Pennsylvania diffracted to 4.0 A resolution at best. On our most 

recent trip to Brookhaven, heavy metal derivatized crystals were tested. A 3.5 i\ ( 

Riso = 15% ) ~~ranium clerivative was obtained currmtly bringing the total to three. 

Preliminary electron density maps have been calculatecl; however, at this stage they 

remain uninterpretable. Arltlitional tlerivatives antl anon~alous information are necessary 

to increase phasing power and calc~~late stronger maps.

X-Ray Structural Studies on OspB, an Immunogenic Outer Surface 

Protein of the Bacteria Borrelia burgdorferi, the Causative Agent X12B, 

X12C 

of Lyme Disease. 

M. Becker, B. Lade, H. Kycia, J.J. Dunn, C.L. Lawson (BNL) and B.J. Luft, 


OspB and OspA are lipoproteins expressed on the surface of the spirochete Bor- 

relia burgdorferi when the bacteria is dormant in the midgut of a host tick. Each 

have been shown to ellicit an immunologic response in infected humans, and both 

are of interest for developing a vaccine against the disease. Recently, the struc- 

ture of OspA has been solved in complex with an antibody Fab fragment [Li, H., 

Dunn, J.J., Luft, B. J., and Lawson, C.L. Proc.Nat.Acad.Sci. USA 94, 3584-3589.1. 

The molecule has an unusually long free-standing anti-parallel 0- sheet, as well as 

a putative binding-site for an unknown ligand in the C-terminal domain. Though 

OspB is highly homologous to OspA, one significant difference is that certain Fabs 

directed at the C-terminal domain of OspB are bactericidal, even in the absence of 

complement [Coleman, J.L. et al. (1992) Infec. Immun. 60, 3098-3104; Sadziene, 

A. et al. (1994) Infec.Immun. 62, 2037-2045.1. The 15.6 kDa C-terminal domain 

of OspB has been cloned, overexpressed, purified, and crystallized in 2 forms. One 

crystal form has space group C2221 with cell constants a = 30.8 A, b = 51.7 A, and 

c = 158.8 A, and contains 1 molecule in the asymmetric unit. Diffraction has been 

observed to at least 1.6-Aresolution at synchrotron beamline X12C of the NSLS, 

and a data set has been collected with 90% completeness, high redundancy, and an 

Rmerge of 6.3% to 2.0-Aresolution at 10 OC at beamline X12B. Molecular replace- 

ment using MERLOT and XPLOR with a search model based on a homology model 

to the OspA C-terminus has been used to locate the monomer in the asymmetric 

unit, but the details of the current model of the OspB C-terminus are unsatisfac- 

tory, particularly at the crystallographic interface formed between the artificially 

truncated molecules. A second crystal form grown in the presence of tungstate has 

the space group P21212 with similar but significantly different axial lengths of a = 

167.7 A, b = 30.2 A, and c = 50.8 A. These crystals diffract similarly well, and a 

data set has been collected at X12C to a resolution of 2.2 A with a completeness 

of 83% and a merging R factor of 6.3% by cooling the crystal to 100 K and using 

radiation at the anomolous peak of tungstate. The anomolous difference Patterson 

reveals a 6-0 peak, indicating that tungstate is specifically bound in the crystal, and 

the Patterson also reveals that these crystals are pseudo-centered. We are currently 

aiming to collect a full MAD data set at the tungstate edge to provide independant 

phasing information to solve the structures. 

I X-Ray Structure of A Six-Finger TGIIIA-DNA Complex I 1 

R.S. Brown, R. T. Nolte, R.M. Conlin and S. C. Harrison (HHMI, Children's 

Hospital Harvard U.) 

The complex containing six zinc fingers of the transcription factor TFIIIA bound 

to 31 base-pairs of the 5s rRNA gene promoter crystallizes in a triclinic form. 

We have successfully determined the structure of this complex at 3.1 angstroms 

resolution. The zinc fingers recognize DNA in two different ways. Fingers 1-2-3 wrap 

as a unit in a continuous fashion around the major groove of DNA. This mode of 

binding has been seen in other zinc finger-DNA X-ray structures. In contrast, fingers 

4-5-6 extend along the DNA crossing the minor-major-minor grooves respectively. 

This structure shows how TFIIIA can recognize several separated DNA sequences 

using fewer fingers than necessary for continuous winding in the major groove. 

Triclinic crystals (space group PI) grow as thin plates and diffract weakly. Collec- 

tion of an X-ray data set takes more than three weeks with a conventional rotating 

anode source. Using the X12-B beam line at NSLS we were able to obtain data 

sets in 24 hours from single frozen crystals. The presence of 12 zinc atoms in the 

unit cell provided an opportunity to use anomalous diffraction as a means to locate 

them. Data were collected at the Zn K-edge using a wavelength of 1.283 angstroms 

at X12-B with a MAR image plate. The positions of all of the zinc atoms in the 

TFIIIA-DNA complex were found in the anomalous Fourier map. These metal sites 

indicate the correct path and fold of the polypeptide chain. 

Figure 1. 

Finger 2

Real-Time Small Angle X-ray Scattering Study of Isotactic 

Poly (propylene) 

P. Dai. G. Georgiev. and P. Cebe (Tufts U.),and N. Cape1 (BNL) 

X12B 

Crystallization and melting of isotactic poly(propylene), iPP, has been studied 

using real-time small angle X-ray scattering. The iPP used in this study is an 

experimental product of Hoechst, and was prepared using homogeneous transition 

metal catalysts (metallocenes). This preparation results in a very narrow molecular 

weight distribution, with hIw/hln = 2.3, and hIw = 335,500. 

\Ve isotherrnallv crystallized iPP by first, melting at 200°C for 2 min. then cooling 

to 124.5C or 117°C at :j°C/min, ancl holding at this temperature for various 

tirne. SAXS data were collected during crystallization arid subsequent heating. 

Data were corrected for: sarrlple absorption, chauges in incident beam intensity, 

background subtraction, antl thermal density fluctuations. The latter correction 

was performed by subtraction of the slope of the linear region at high s. in the 

Is4 vs. s4 plot. Sample-to-detector distance was 1.75rn and was determined using 

cllolesterol myristate antl collagen fiber. X-ray wavelength was 1.54 i-1, and intensity 

was collected with an integration time of 30 sec. 

Analysis of the corrected intensity was tlorie usirtg the one-dimensional electron 

density correlation fmxtion, where the density variation was assumed to occur 

along a tlirectiort norrnal to the coherently scatterirrg stacks of lamellar crystals. 

Long period, Iarriellar thickness, ant1 linear crystallinity of the lamellar stacks were 

calc~tlated frorrt the correlation function. \\re find that the long pcriotl (distance 

between ac1,jaccnt larnellae) decreases tl~iring isothermal crystallization at 117°C or 

124.:i°C. Upori reheating, long pcriod increases tlranlatically as the mcltirlg region 

is approarhetl. Once the melting peak ter~tpcrature has been exceeded, lortg period 

tlerrc~asc~s. Altho~tgtl the melting cntlotkterrrls observed using thermal analysis show 

"tloublc mcltirig" hetlavior, wc did not observe any syste~natic variation of the 

long pcriotl through the temperitt,~irc region corresponcling to the lower melting 

e~ltlotherrrt. 

I hIechanica1 Behavior of Novel Block Copolymer hIorphologies I X12B I 

B.J. Dair (LIIT), E.L. Thomas (hlIT), h1.C. Cape1 (NSLS) 

Novel cubic phases have recently been discovered in copolymer systems. including 

the ordered tricontinuous double gyroid (DG). DG conforms to the symmetries of 

the Ia3d space group and has a tricontinuous, triply periodic structure, whereby 

two non-intersecting networks of the minority phase are embedded in the majority. 

Recently we have identified and obtained triblock copolymers which form cubic 

morphologies, opening up the possibility of investigating the mechanical properites 

of these new morphologies. At X12B, we investigate the large strain mechanical 

properites of styrene-isoprene-styrene triblock copolymers with DG morphology. 

Tensile samples were prepared from macroscopically oriented. near-single-crystal 

sheets of DG. which were produced via roll- cast processing ancl annealing. In-situ 

X-ray patterns, along with simultaneous load-deformation curves, were taken as 

specimens were loaded in uniaxial tension. Due to the resultirtg long-range order, 

such samples are nlechanically anisotropic and scatter anisotropically. Hence, a 

stlidv of the cleforrnation behavior of this structure via S AX requires the use of a 

2-dimensional detector, and particularly that at X12B.

CU 

Glutamine Synthetase from Mycobacterium Tuberculosis: Aim To- 

ward Drug Discovery I X12B I 2.1 A Structure of the Complex Between Active Ras and The Ras- ~ 2 5 , 

Interacting Domain of an Effector RalGDS I X12B I 

H. Gill and D. Eisenberg (UCLA) 

Tuberculosis (TB) has re-emerged as a gobal health concern. Previous studies 

have indicated that Glutamine Synthetase from Mycobacterium tuberculosis, the 

pathogen behind the disease TB, may be involved in a novel role via its secretion 

from the organism (Harth et al., 1994). Secreted GS is an attractive target for drugs, 

because the drugs need not penetrate the thick cellular envelope of Mycobacteria 

in order to combat the disease. We have set out to elucidate the structure of TB- 

GS as part of the goal to find a drug to selectively inhibit TB-GS over human 

GS. Synchrotron radiation was a necessary part of this process. As illustrated in 

Figure 1, approximately 2.6 million reflections were recorded, with 566,370 unique 

reflections yielding a redundancy of 4.6 and a R,,, of 7.5, in a 23 hour time period 

at the National Synchrotron Light Source X12B Beamline using the new Quantum- 

4 CCD detector (Area Detector San Diego Company). The space group is P212121 

with unit cell dimension 208 x 255 x 274 A using the MOSFILM program for data 

processing to 2.4 A resolution. Self-rotation functions, calculated on the data set 

using the program POLARRFN, revealed six aligned and equally spaced non-origin 

peaks in the appa=180 section and one non-origin peak- 90 degrees away from these 

2-folds- in the kappa=60 and 120 sections consistent with the 622 symmetrical 

architecture of Salmonella typhimurium GS. A VM calculation of 2.89 indicates 

two dodecamers (24 subunits) in the asymmetric unit. Since only one set of two- 

fold and six-fold axes are apparent in the rotation function, we conclude that both 

molecules face each other along the crystallographic axis. The TB-GS model has 

been solved using an initial model of S. typhimurium GS, which has been refined 

to 2.5 A resolution in our laboratory. The simulated annealing protocol, thus far, 

gives a R-factor of 38 percent. Model building is currently in progress using 24 

NCS-averaging methods. Hence. svnchrotron radiation at beamline X12B and the 

new CCD dvetgctor was crucial tb solving the TB-GS structure. 

Figure 1. View of the H=O, K=O sections using the PLOTHKL program G. Pfluegl 

(UCLA). 


The structure of the complex bewteen oncogenic protein Ras and the Ras- inter- 

acting domain of RalGDS (RalGDS-RID) has been studied by x-ray crystallography. 

The structure of the complex will provide crucial information on Ras' interaction 

with its binding partner at an atomic level. Since the mutant forms of Ras are 

involved in 30% of human cancer and Ras' function is carried out through its effec- 

tors, the spatial location of the key interface residues may assist in identifying small 

molecules that are capable of disrupting this interaction and thus provide insights 

for the development of anti-cancer drugs. A 2.8 room temperature data set on a 

native complex crystal was initially taken at BL X12B, which enabled us to solve 

the structure. A 2.0 frozen data set was later taken at BL X25 in september, which 

enabled us to refine the structure to a much higher resolution so that we can see the 

side chain interaction more clearly. The crystal has a P212121 space group, with 

a=75.648, b=78.256, c=87.313 . The complex crystallizes as a heterotertramer with 

two active Ras molecules and two RalGDS-RID subunits. 

Figure 1.

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o 

rP 

Vancomycin-Ligand Complex Structures 

P.J. Loll (U. of Pennsylvania) 

Structures of complexes of the glycopeptide antibiotic vancomycin with peptide 

and depsipeptide ligands have been determined at atomic resolution by single- 

crystal X-ray diffraction methods. using data collected at NSLS and the new direct 

methods program SnB. These structures reveal asymmetric dimer formation in all 

complexes. but also show that strong ligands are able to fill both dimer binding sites. 

whereas weak ligands give complexes with a 2:l antibiotic:ligand stoichiometry. This 

structural information is being used in conjunction with simulation mcthocls to un- 

derstand the molecular basis of target recognition by this class of antibiotics, and 

will ultimately aid in the design of new agents to combat antibiotic resistance. 

6 

X12B 

Figure 1. ORTEP drawing of the complex of ~ancomycin with S-acetyl-D-alanine. 

The Crystal Structure of the DNA Binding Domain of the Orphan 

Nuclear Rece~tor NGFI-B Comdexed to its DNA Target at 2.7 A 

G. Meinke, P. Sigler (Yale University) 

X12B 

The nuclear receptor superfamily is a large group of proteins which are ligand 

dependent transcriptional modulators. This family includes receptors for a diverse 

group of ligands such as steroids. retinoic acid, vitamin D. and thyroid hormone. 

These receptors bind to a specific DNA sequence termed a hormone response element 

(HRE). The receptors bind as home or heterdimers or monomers to a 

6 base pair consensus sequence termed a half-site which can be organized as direct, 

inverted, or everted repeats with variable number of spacer nuclcoticles or as 

monomers with a 5f extension to the half-site. 

The X-ray crystal structure of the DNA bincling domain (DBD) of the orphan 

nuclear receptor nerve growth factor induced-B (NGFI-B) complexcd to its high 

affinity DNA target has been refined to 2.7 ,&. The structure represents the first 

example of a nuclear receptor bound as a monomer to its specific DNA target. 

The DNA target consists of the consensus hexameric half-site AGGTCA with a 51 

flanking sequence of A. The fold of the core DBD is nearly identical to previously 

solved structures of other members of the nuclear receptor. Residl~cs C-terminal to 

the core DBD form a stable structure which interact with the minor groove of the 

DNA via an extcritlecl loop. These minor groove contacts occur iri the half-site as 

well as the 5f flanking basepairs.

Determination of Mitochrondrial Cytochrome bcl Com- I X12B 1 

D. Xia (HHMI and U. of Texas SW Medical Center) C. A. Yu (Oklahoma State 

U), H. Kim (HHMI and U. of Texas SW Medical Center), A. Kachurin, L. Zhang, 

L. Yu (Oklahoma St. U.) and , J. Deisenhofer (HHMI and U. of Texas SW Medical 

Center) 

Cytochrome bcl Complex (ubiquinol-cytochrome c oxidoreductase, bcl) is the 

middle segment of the respiratory chain in almost all aerobic organism, and an es- 

sential component in the photosynthetic machinary in purple bacteria. Green plants 

use highly homologous b6f complex as an important part of their energy conserva- 

tion apparatus. The bcl complex is an integral membrane protein; it couples the 

electron transfer from ubiquinol to cytochrome c to the proton translocation across 

the membrane to generate a pH difference and a membrane potential for ATP 

synthesis. Mitochondria1 bcl complex from bovine heart consists of 11 different 

subunits, two b-type hemes, one c-type heme and an iron-sulfur cluster with a total 

molecular weight of 250 Kd and in excess of 2200 amino acid residues. 

The mitochondrial cytochrome bcl complex from bovine heart was purified and 

crystallized. bcl crystals can be cry0 frozen for stable data collection at Synchrotron 

radiation sources. bcl crystals diffracted X-ray at X12B of NSLS to 3.3 A resolution 

and possess symmetry of the space group of I4122 with cell dimensions of a=b=153.7 

A and c=597.5 A. Initial phases for the bcl crystal were determined using MIRAS 

method with seven heavy metal derivatives, and subsequent phase improvment were 

carried out with cyclic excutions of density modification and phase combination 

procedures. Current atomic model of the bcl complex contains eight completely 

sequence assigned subunits including corel, core2, cytochrome b, Rieske iron sulfur 

protein, subunits 6, 7, 10 and 11; three incomplete subunits including cytochrome 

cl, subuints 8 and 9; two b-type hemes, one c-type heme and one 2Fe2S iron-sulfur 

cluster with total number of amino acids residues near 2000. 

The bcl structure in crystal is a tightly associated dimer about 155 A tall and 

130 A wide. It can be divided into three regions, the membrane spanning region, 

48 thick, has 26 trans-membrane helices in the dimer, sixteen of which belong to 

cytochrome b dimer. Cytochrome cl, Rieske protein, subunits 7, 10 and 11 each 

contributes two helices in the dimer. The intermembrane space region of the bcl 

complex rises 38 A into the intermembrane space where the soluble parts of the the 

Rieske iron-sulfur protein and cytochrome cl are located. The matrix region of the 

bcl projects 75 A into the mitochondrial matrix where corel, core2, subunit6, parts 

of Rieske, cytochrome cl, subunits 7, and 9 can be found. 

The stuctural information of the bcl complex has provided significant contribu- 

tion to our understanding of the redox-coupled proton translocation mechanism. 

1 

Structural Studies on the Complex of the C-terminal Domain of 

Outer Surface Protein B of Borrelia burgdorferi with a Bactericidal 

Fab. 

M. Becker, B. Lade, W. Ding, J.J. Dunn, C.L. Lawson (BNL), J. Bunikis, A.G. 

Barbour (UC at Irvine), and B.J. Luft (SUNY at Stony Brook) 

Outer Surface Protein B (OspB) is a lipoprotein of unknown function found on 

the surface of Borrelia burgdorferi, the causative agent of Lyme Disease. It has 

been shown that certain antibodies directed at the C-terminal domain of OspB are 

bactericidal, and surprisingly, that the Fabs alone of these antibodies are bacterici- 

dal, even in the absence of complement [Coleman, J.L., Rogers, R.C., and Benach, 

J.L. (1992) Infec.Immun. 60, 3098-3104; Szaziene, A,, Jonsson, M., Bergstrom, S., 

Bright, R.K., Kennedy, R.C. and Barbour, A.G. (1994) Infec.Immun. 62, 2037- 

2045.1. Crystals of a complex of the 15.6 kDa C-terminal domain of OspB with 

bactericidal Fab H6831 have the space group C2 with cell constants a = 186.3 A, b 

= 37.3 A, c = 87.9 A, and P = 90.7 O, contain 1 complex per asymmetric unit, and 

diffract initially to at least 2.0-Aresolution at 18 O C. A data set with complete- 

ness of 94% and an Rmerge of 7.8% has been collected to 2.6-Aresolution at 18 ' 

C by merging data from different crystals collected at beamline X12C. Molecular 

replacement using the program AMORE with the structure of an Fab directed at 

OspA of Borrelia burgdorferii [Li, H., Dunn, J.J., Luft, B.J., and Lawson, C.L. 

(1997) Proc.Nat.Acad.Sci. USA 94, 3584-35891 as a search model provides a clear 

solution to the location of the Fab in the asymmetric unit, and efforts to determine 

the structure of the C-terminal domain of OspB in the complex are currently un- 

derway. Also, freezing conditions for the crystals are being tested so that data can 

be collected to higher resolution.

tj 

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a 

C, 

X-Ray Structural Studies on OspB, an Immunogenic Outer Surface 

Protein of the Bacteria Borrelia burgdorferi, the Causative Agent 

of Lyme Disease. 

X12B, 

X12C 

AI. Becker. B. Lade, H. Kycia, J.J. Dunn, C.L. Lawson (BNL) and B.J. Luft. 


OspB and OspA are lipoproteins expressed on the surface of the spirochete Borrelia 

burgdorferi when the bacteria is dormant in the midgut of a host tick. Each 

have been shown to ellicit an immunologic response in infected humans. and both 

are of interest for developing a vaccine against the disease. Recently, the structure 

of OspA has been solved in complex with an antibody Fab fragment [Li, H., 

Dunn, J.J., Luft, B.J., and Lawson, C.L. Proc. Nat.Acad.Sci. USA 94, 3584-3589.1. 

The molecule has an unusually long free-standing anti-parallel 8- sheet, as well as 

a putative bintling-site for an unknown ligancl in the C-terminal tlornain. Though 

OspB is highly homologous to OspA, one significant difference is that certain Fabs 

directed at the C-terminal domain of OspB are bactericidal, even in the absence of 

complement [Coleman, .J.L. et d. (1992) Infec. Immun. GO, 3098-3104; Satlziene, 

A. et al. (1994) Infec.Imm~~n. 62, 2037-2045.1. The 15.6 kDa C-terminal tlornain 

of OspB has been cloned. overexpressetl, purified, ancl crystallized in 2 forms. One 

crystal form has space group C2221 with cell constants a = 30.8 .A, b = 51.7 A, and 

c = 158.8 A, antl contains 1 molecule in the asymmetric unit. Diffraction has been 

observed to at least 1.6-L&resolution at synchrotron bearnline X12C of the NSLS. 

antl a data set has been collectecl with 90% completeness, high redundancy, and an 

Rnlerge of 6.3% to 2.0-&esolution at 10 OC at beamline X12B. hIolecnlar replacement 

using LIERLOT antl XPLOR with a search rnotlel based on a homology rnotlel 

to the OspA C-terminus has been used to locate the rnonorner in the asymmetric 

unit, but the details of the cwrent model of the OspB C-terminus are ~msatisfactory, 

particularly at the crystallographic interface formed between the artificially 

trnncated rnolecnles. A second crystal form grown in the presence of tnngstate has 

the space group P21212 with similar bnt significantly different axial lengths of n = 

167.7 A. b = 30.2 and c = 50.8 A. These crystals diffract similarly well, and a 

data set has been collected at X12C to a resolution of 2.2 '4 with a completeness 

of 83% and a merging R factor of 6.3% by cooling the crystal to 100 K and wing 

radiation at the ano~nolo~~s peak of tungstate. The anomolo~~s tliffrrence Pattrrson 

reveals a fi-cr peak. indicating that t~mgstntr is specifically bormd in the crystal, antl 

the Patterson also rcvcals that these crystals arr psrndo-centered. I\ arc currently 

aiming to collect a full SIrlD data set at the tungstate etlgr to provitle indrpentlant 

phasing infornlation to solve the structures. 

I MAD Studies of the Bacteriophage PRDl RlIajor Coat Protein, P3 * I X12C I 

S.D. Benson (The Wistar Instit.), J.K.H. Bamford, D.H. Bamford (U. of Helsinki), 

and R.hI. Burnett (The Wistar Inst.) 

PRDl is an unusual bacteriophage with many structural similarities to the mammalian 

adenovirus. Both are icosahedral with vertex fibers, have trimeric major 

coat proteins, and contain linear ds-DNA with terminal proteins. PRDl is unique 

in posessing a lipid membrane within its outer capsid, which is composed of two 

proteins, P3 ancl P5. P5 lies at the vertices. while P3, a homotrimer of 394 amino 

acids. forms the facets with its N-termini interacting with the internal viral membrane. 

The structure of P3 promises an increased unclerstanding of viral capsid 

assembly and membrane interactions. Crystals of P3 are orthorhombic (P212121: a 

= 117.9 A, b = 121.3 A. c = 126.4 A) with a trimer in the asymmetric unit. 

Initial heavy aton1 trials were troubled by crystal disruption and nonisomorphism. 

A hIultiwavelength Anomalous Dispersion (hIAD) experiment at the 

NSLS wx designed to overcome these problems. PRDl was expresscd in a bacterial 

systenl containing selenornettlionine and mass spectrometry sl~olvctl >90% substitution. 

Crystals were obtained under the same conditions as the native protein. 

A three wavelength hIAD experinlent was performed around the absorption edge 

of seleniurn on a single frozen seler~ornetl~ioriir~e P3 crystal at beamli~le X12C. The 

data were collected with a CCD-based detector to 2.2 .4 resolution. The positions of 

the 15 selenium atoms were tleterrninetl from difference Fourier maps with phasing 

information from a urauyl acetate derivative. Native data to 1.8 ;I resolution also 

were collectecl. Crystals of the entire virion, grown in microgravity on the space 

shuttle, did not diffract but trials continue with a fiberless variant. 

Althongh the P3 trimer is one of the largest strl~ctures to lw solved with hIAD 

phasing from selenornethionine, the initial electron density map at 2.2 ;1 resolution 

was superb. AIodel hiltling for 81% of the polypeptitle chain was m~aml~ig~~on~ ard 

refinement of the st,ructure is ~n~tlerway. 

Figure 1. -4 representative section of the MAD-phased 20 electron density map for 

PRD1-P3 containing model residues 161-165. 

Supported by SSF Grant 1ICB 95-07102 and the Finnish .Academy of Sciences.

X-ray Structural Study of Lyme Bacterium Outer Surface Protein 

A Complexed With a mAb LA2 Fab Fragment by Multiwavelength 

Anomalous Diffraction Experiment 

X12C 

W. Ding (SUNY at Stony Brook), B.J. Lufts, X. Yang (SUNY at Stony Brook), J. 

J. Dunn, and C.L. Lawson (BNL) 

Lyme disease is the most common vector borne illness in the United States,caused 

by spirochete Bomelza burgdorferz. Earliest infection is marked by the appearance of 

erythema migrans. Left untreated, early dissemination may give rise to multisystem 

illness with dermatologic, rheumatic, cardiac and neurologic manifestions. 

Preliminary studies have shown the OspA based vaccine can induce protective 

immunity in mammals. Protection appears to be serotype specific. In vaccine stud- 

ies with hamsters, protection was conferred only when hamster's immune response 

was directed to the epitope defined by the mAb LA2. Subsequent studies have 

concluded that the mAb LA2 binds to a conformational epitope located near the 

carboxyl terminus with the stretch of amino acid from 133 to 273. This section of 

OspA is a hypervariable region. However there is a single conserved tryptophan 

at amino acid 216, and fragmentation at this point destroys mAb LA2 binding. 

Studies of a series of OspA fusion proteins, deletion proteins, site-directed mutants, 

strain chimeric proteins and different strains by Western blot analysis suggests that 

the mAb LA2 recognizes a 29 amino acid chain on OspA located at a amino acid 

positions 190 - 217 and supports the theory that epitope is conformationally depen- 

dent. Defining this protective epitope is an important consideration in developing 

an effective vaccine for Lyme disease protection. In order to better define and un- 

derstand the epitope of OspA, we have initialized a structural study of OspA and 

LA2 Fab fragment. 

Crystals were grown at 4OC by hanging-drop vapour diffusion methods ( 0.1M 

Sodium cacodylate, 0.1M sodium Acetate and 10% PEG 3300 at pH 6.15). Crys- 

tals were mounted in a glass capillary tubes (0.7 mm in diameter) and data were 

collected on X12C, NSLS CCD detector (Brandeis University) with crystal tem- 

perature maintained at 4OC with a cooling air stream. Diffraction patterns were 

observed with dmin = 3.0A. The crystal lattice was determined to be orthorhom- 

bic with dimension a =99.5A b=129.5.& c=144.5A . Assuming two OspA -LA2 fab 

protein complex molecular per asymmetric unit with molecular mass 81 kDa, the 

specific volume (Vm) is 2.9A /Da, corresponds a solvent content 50%, well inside 

the observed range for protein crystals. 

A complete four-wavelength MAD data set on one Na2W04 derivatized crystal 

was collected at the X12C with crystal frozen in a stream of gaseous nitrogen held 

at 100K. The crystal diffracted to 3.2A and the data set has 96% completeness. The 

data collection and phasing stragegy of treating MAD as a special case of MIR was 

applied to obtain phase information. Isomorphous and dispersive patterson maps 

calculated from the data set showed strong heavy atom binding site peaks (fig 2). 

The positions were refined and used to calculate the phases. The electron density 

map is interpretable. We are in the process of the model build-up and refinement. 

[crystallization and Analysis of Native and Derivative X-Ray Diffrac- I , , I ALLb 

I tion Data from Bovine Milk Xanthine Oxidase * 

B. Eger (U. of Toronto), K. Madrid (Aastra, Inc.), K. Okamoto, M. Sato (Nippon 

Medical School), K. McConville (Aastra, Inc.), T. Nishino (Nippon Medical school), 

and E.F. Pai (U. of Toronto) 

Xanthine oxidase or xanthine dehydrogenase isolated from mammals is a component 

of the nucleotide catabolism pathway. The active enzyme, a 290kdal homodimer, 

catalyzes the oxidation of hypoxanthine to xanthine, followed by further 

oxidation to uric acid. The enzyme, which is synthesized in vivo as xanthine dehydrogenase, 

contains one FAD, two 2Fe/2S centers, and one molybdopterin group 

per monomer. Extensive studies on the mechanism of electron transfer between the 

cofactor sites have been made on both the oxidase and the dehydrogenase forms. 

Elucidation of the three dimensional structure of the enzyme is an important step in 

the study of electron transfer between the cofactor and the substrate binding sites. 

Recently, a purification scheme for xanthine oxidase was developed which yields enzyme 

preparations of exceptional purity. Large crystals (1.2 x 0.7 x 0.15mm) were 

obtained using polyethylene glycol 4000 as a precipitant. However, due to the weak 

diffraction of these crystals, data had to be obtained from a synchrotron radiation 

source. The lattice type of these crystals was orthorhombic (C2221) with unit cell 

dimensions of a=118.6, b = 165.4, c = 156.4. From the Matthews parameter, there 

was one monomer per asymmetric unit and a solvent content of 56%. A native 

data set was collected which was 95.2% complete to 3.3 with an overall R factor of 

9.2% from 107172 measured reflections and 22347 unique reflections. Since no analogous 

structure has been solved, screening for heavy atom derivatives has begun. 

Currently, two complete data sets have been collected of possible weak derivatives. 

In addition, prelimiary diffraction data from five potential derivatives have been 

screened which show promising results. Each of the five sets diffracts well, has unit 

cell parameters similar to the native unit cell values, and scale to the native data set 

with R factors in the ranae of those ex~ected for a derivative data set. Additional 

synchrotron beam time $11 be used for collection of these data sets and screening 

of additional heavy atoms. 

* Supported by National Science and Engineering Council of Canada

46 

F--L 

0 

Co I Structural Studies of Nucleosomes. * I X12C I 

J. M. Harp, D. E. Timm (UTK), and G. J. Bunick (ORNL) 

Previous data collection done at the NSLS beamline X12C has provided high 

quality native diffraction data from crystals of nucleosome core particles and of 

the histone octamer core of the nucleosome. The nucleosomes in that study were 

prepared using a 146 bp DNA palindrome based on a nucleosome binding sequence 

in the alpha satellite DN-4 of the human X-chromosome. The DNA was bound to 

histones purified from chicken erythrocytes. The DNA palindrome extends the 2 

fold symmetry of the octamer core to the entire complex and the use of an alpha 

satellite sequence provided the highest quality crystals for X-ray diffraction. The 

histone octa~ner crystals mere grown from the same batches of protein as that used 

for nucleosome assembly. Recent studies done at beamline X12C have been designed 

to provide data to be used in solving the phases of the previous native data 

sets. The nucleosomes were assembled using the same DNA palindrome hut with 

recombinant histone octamers. The recombinant histones were also n~utagenizetl to 

introduce additional binding sites for heavy atom derivatives. MAD experiments 

were performed using crystals of the histone octamer derivatized with mercury and 

a crystal of the nl~cleosome core particle derivatized with a platinunl compound. 

All data were collected at 100 K and crystals were annealed to lower ~nosaic spread 

caused by fla.sh-cooling. 

* Research sponsored by the Office of Health Environmental Research. Department of 

Energy. under contract So. DE-.AC05-960R22161 with Lockheed llartin Energy Research 

Corp.. ancl SIH Grant GlI29818 

X-ray Structural Study of Equine Infectious Anaemia Virus Capsid 

Protein p26 

Z. Jin (SUNY at Stony Brook), A.J. Birkett, L. Jin, D.L. Peterson (VA Common- 

wealth U.) and C. L. Lawson (BNL) 

Equine Infectious Anaemia Virus (EIAV) belongs to the Lentiviridae family, 

which is a snbfamily of Retrovirus. EIAV is responsible for a chronic, debilitating 

disease in horses. Infection has been reported worlcl-micle and EIAV is recog~lizecl as 

a livestock pathogen of significant economic importance to the horse industry. There 

is significant homology between the non-human lentiviruses ancl HIV-1, which is the 

most extensively studied member of Lentiviridae family. Lentiviral capsicl proteins 

play a crucial role in the maturation of infectious viral particles. Interference with 

particle maturation would provide an anti-viral mechanism. EIAV anti HIV-1 cap- 

sit1 proteins have 30% identity antl 55% similarity of their amino acid sequences. 

The structural study of EIAV core protein mill help in untlerstantlirig the structure 

of HIV core protein, and in evaluating methods of effective treatment and control 

of viral infection. 

Crystals were grown at room temperature by hanging drop vapor cliffusion with 

0.1 51 Citrate bnffer and 10% PEG 3300, 15% isopropanol, at pH 6.5. A complete 

native data set to 3.6 A (R,,, = 11%) has been collected at the bearnlirie X12C of 

National Synchrotron Light Source at Brookhaven National Laboratory. Crystals 

belong to the space group P6122 with a=b=lOl A and c=158 A. 

A complete three-wavelength hIAD tlata set on one Pt tlerivatiaetl crystal was 

collected on the X12C hearr~line using CCD (Brantleis Universit,y) detector. The 

crystal diffracted to 3.11 i\ and the tlata set has 98% completeness. The tlata 

collection ancl phasing strategy of treating hIAD as a special case of 1IIR (V. Ra- 

makrishnan et nl., from Methods in Enzymology 1997) was applied to obtain phase 

information. Ison~orplious and dispersive patterson maps calculated from the data 

set showed strong heavy atom binding site peaks (fig 1). The positions were refined 

antl usetl to calculate the phases. The electron density map is interpretable and 

the N-terminal and C-terrninal tlornains are intact. The ambiguity of space groups 

PCi122 antl PGi22 was resolved by warning the the electron density map; the PCi;22 

has the wrong configuration with left-hand helices and was exclutletl. The crystal 

contains two p26 protomers per asymmetric unit. \ire are in the process of the 

model building and refinement. 

Figure 1. Dispersive Patterson map on Harker section z = 1/6

Crystal Structure of Complexes of Human Acetylcholinesterase and 

Various Nerve Agents 

X12C 

G. Kryger, I. Silman, J.L. Sussman (The Weizmann Institute of Science, Israel) 

Acetylcholinesterase (AChE) is responsible for terminating the action of the neu- 

rotransmitter acetylcholine by rapid hydrolysis to choline and acetic acid. AChE is 

also the target of many insecticides and other reversible and irreversible inhibitors 

from the organo-phosphate family, of which some have unfortunately been used as 

nerve agents in chemical warfare. Accurate structural knowledge of the structure 

of complexes of such inhibitors with human AChE is therefore of great importance 

in the development and design of more specific insecticides and more important, 

the development of anti nerve agent treatment. Complexes of recombinant hu- 

man AChE (rhAChE) with 0-ethyl S-(2-diisopropylaminoethyl) methylphospho- 

nothioate (VX), diisopropyl fluorophosphate (DFP) and sarine (SAR) were pre- 

pared in solution, then reacted with equimolar amounts of Fasciculin-I1 (FAS-11) 

and crystallized. Crystals of about 0.2mm and space group R32 were used for data 

collection at the BNL-NSLS X12-C X-ray source. Structure determination was car- 

ried out by molecular eplacement based on the structure of rhACh/FAS-I1 obtained 

at the same beamline and refinement of rhACh/FAS-II/VX, rhACh/FAS-II/DFP 

and rhACh/FAS-II/SAR is underway. 

I ~ ltEa 

I Endonuclease from Serratia marcescens. * 

M.D. Miller (U. Houston) & K.L. Krause (U. Houston/Baylor Col. Med.) 

High Resolution Protein Structure Studies of the Extracellular I , , I 

Aldb 

We are refining and characterizing protein structures at ultra high resolution 

(>1.0 A) using data from the extracelluar endonuclease from Serratia marcescens'. 

When crystals are cooled to 100 K, diffraction is seen beyond 0.9 A resolution. 

One dimer of the endonuclease (53.4 kDa / 490 amino acids) crystallizes in the 

asymmetric unit of space group P21212 with a=106.7 A, b=74.5 A, c=68.9 A. 

Before our visit to NSLS, data had been collected to 0.92 A with a MAR image 

plate system on the EMBL beamline BW7B at DESY (A = 0.89 A). 

During our recent trip to the NSLS beamline X12C at BNL, we were interested 

in extending the resolution and testing the X12C setup for ultra high resolution 

data collection. Data from a single crystal cooled to 100 K were collected to 0.88 A 

resolution (Fig. 1). Three data collection sweeps were used. The two high resolution 

sweeps differed by 40" in x and the third sweep was to collect low resolution data. 

Exposure times were on the order of 12 minldegree for the high resolution data. 

Figure 1. Diffraction image of the Serratia endonuclease crystals taken on beamline 

X12C using the 1K CCD detector (A = 0.95 A). The upper edge of the image is 

0.89 A and the upper left corner is 0.87 A resolution. The zoomed image (right) 

shows diffraction to the edge of the detector. 

'~iller MD & Krause KL. Protein Sci 5, 2433 (1996); Miller MD, Tanner J, 

Alpaugh M, Benedik MJ & Krause KL. Nature Struct Biol 1, 461-468 (1994). 

* This research is supported by the NIH, The Robert A. Welch Foundation, The 

Methodist Hospital Foundation, the W.M. Keck Foundation, and the State of Texas ARP

+ 

0 

Crystallographic Studies on the Non-enzymatic Plasminogen Acti- 

vator Stre~tokinasee 

C. Phillips (LR,IB, Oxford). G. Spraggon (UCSD) and D.I.Stuart (LRIB, Oxford) 

Streptokinase (SK) is a bacterial protein from Streptococcus equisimilis that 

indirectly causes the activation plasminogen (Plg). SK and Plg form an avid 1:l 

stoichiometric complex with the subsequent appearance of a serine protease active 

center from within the Plg moiety: this complex acts in turn as an activator of other 

Plg molecules. SK has shown itself to be an efficacious agent in the clinical treatment 

of acute myocardial infarction ( heart attack ) and has served as a thrombolytic 

agent for almost three decades. Recently SK has been shown to consist of three 

donlains termed A.B and C, of molecular weight lGK, 17K antl 11K respectively. 

Donlain B has been shown to contain the Plg binding site. Data were collected from 

cryo-cooled crystals of domain B on station X12C ming a CCD detector. Several 

derivative data sets were collectetl, antl a multi-wavelength experiment performed 

using a promising platinum derivative. 

Crystal Structure of the Rhiaomucor miehei Aspartic Proteinase 

X12C X12C 

Complexed with the Inhibitor Pepstatin A at 2.7A. 

J.W. Quail and J. Yang (U. of Saskatchewan) 

The crystal structure of the Rhizomucor miehei aspartic proteinase (RhlP) complexed 

with the inhibitor pepstatin A has been determined from 2.7A data collected 

at X12C in November: 1996. The crystals were thin and did not diffract to a sufficiently 

high resolution with a copper tube x-ray source. With the 2.7A data 

obtained at NSLS it was possible to see more bonding detail for this complex. The 

crystals of the RhlP-pepstatin A complex form in the orthorhomic space group 

P212121. The unit cell dimensions are: a=41.52A, b=50.82A and c=172.71A4. The 

data was refined to an R factor of 19.3% antl an R-free of 28.0% at 2.7A. In the final 

motlel, a pepstatin A rnolecule fits into the large substrate-binding cleft between 

the two donlains of RhIP in an extended conformation up to the alanine at the 

P2' position. The dipeptidc analogue statine residue at the P3'-P4' position forms 

an inverse y-turn (P3'-PI') with the statine residue at the PI-PI' position, and 

its leucyl side chain binding into the S1' snbsite. The inhibitor interacts with the 

residues of the sllbstr:ttc-bintlirlg pocket by either hydrogen bonds or hydrophobic 

interactions, or both. The hytlroxyl group of the statine residue at the PI-P1' position 

fornls hydrogen bonds with both the catalytic aspartate residues (Asp38 x ~cl 

Asp237). This conformation rni~nics the expected transition state of the enzymesubstrate 

interaction. The birding of the inhibitor to the enzvrrle docs not protluce 

large distortions of the active site. No tlonlain move~ncrtt is observed relativc to the 

riative enzyme strl~cture. However, the surface flap region (resitlws 82 to 88) 1111tlergoes 

a conforn~ational change. It rnoves toward the inhibitor and becomes rigid 

tluc to the formation of hydrogen bonds with the inhibitor. B-factor calculations 

of the two rlonlains suggests that the C-terrninal tlorriain hecornes morc rigitl in the 

complex than in the native structure.

+ 

Structures of UMP Kinase Transition State Analogue Complexes 

Suggest Mechanism of Phosphoryl Transfer is Associatieve 

I. Schlichting and J. Reinstein (Max Planck Inst. for Molecular Physiology, GE) 

Nucleoside monophosphate (NMP) kinases (ATP:NMP phophotransferases) cat- 

alyze the reversible transphosphorylation between nucleoside triphosphates and nu- 

cleoside monophosphates. NMP kinases play a major role in the regulation of the 

concentration of nucleoside diphosphates in the cell1']. To obtain a better under- 

standing of the enzymatic mechanism of NMP kinases we have studied UMP/CMP 

kinase (UK) from Dictyostelium discoideum by kinetic and crystallographic meth- 

ods. It is difficult to apply time-resolved crystallographic approaches to this class 

of enzymes as NMP kinases employ an induced-fit mechanism involving large con- 

certed motions that appear to be incompatible with maintainance of a well-ordered 

crystal lattice. Thus, we determined the three-dimensional structures of UK com- 

plexed with ADP, CMP, Mg2+ and transition state analogs (aluminum, beryllium 

and scandium fluoride) of the phosphate being transfered"]. We measured the ki- 

netic parameters of these analogs and found that all three analogs form rather tight 

complexes with the enzyme. Diffraction data of the crystals (P41212, a=b=78.8 

A, c=100.7 A) of UK, ADP, CMP, Mg2+ grown in the presence of aluminum or 

beryllium fluoride are 93%% complete to 1.9d with R,,,,, of 8.7%% and 90-% 

complete to 1.65 with R,,,,, of 6.1%% , respectively. The structures were refined 

with XPLOR 3.1 using the structure of the UK complexed with the specific and 

asymmetric bisubstrate inhibitor pl-(adenosine 5')-~~-(uridine5')-~enta~hos~hate 

(UP5A) as a starting model (omitting the nucleotide, Mg2+, and waters). The 

positions of the catalytic M ~ and ~ + the highly conserved lysine of the P loop are 

virtually invariant in the different structures. In constrast, catalytic arginines move 

to stabilize charges that develop during the phosphyl transfer reaction. The location 

of the arginines indicates formation of negative charges during the reaction at 

the transferred phosphoryl group, but not at the phosphate bridging oxygen atoms 

(see figure). This is consistent with an associative phosphoryl transfer mechanism 

but not with a dissociative one. 

[l] Schlichting, I. & Reinstein, J. (1997) Biochemistry 36: 9290-9296. 

Figure 1. Stereoview of the UmpK.ADP.CMP.A1F3.Mg2+ complex. Interactions 

between A1F3 and arginine residues are shown by dashed lines. 

I Crystal Structure of I-Dm01 by MAD Phasing 

G. Silva and P. Van Roey (Wadsworth Center) 

I ~ 1I 2 ~ 

I-Dm01 is a 22kDa intron-encoded endonuclease from the hyperthermophilic 

archeaon Desulfurococ~us mobilis. Crystals of I-Dm01 belong to space group C2, a 

= 94.2 A, b = 37.16 A, c = 55.78 A, ,O = 113.3. Previous attempts at determin- 

ing the structure of I-Dm01 by conventional MIR methods have failed because of 

high mosaicity and non-isomorphism problems. MAD data (3 wave lengths) were 

measured for a Selenomethionine derivative crystal. For each wavelength, the data 

within an oscillation range of 160 degrees, and in its Friedel flip, were measured 

over a 36 hr. period, using one crystal. The data are 99% complete to 2.2 A, with 

about 11-fold redundancy. The data were processed with DENZO/SCALEPACK. 

Rmerge values for each data set are 0.051 to 0.059. Phasing and solvent flatttening, 

using the package PHASES, has yielded a map that is easily interpretable. Model 

building is currently in progress.

tj 

+ 

r I Structure Determination of Novel Proteins I X12C I 

to 

W. Smith, X. Qiu. N. Concha, B. Zhao, 1LI. Swairjo. S. Abdel-hfeguid (SmithKline 

Beecham Pharmaceuticals) 

Single crystal x-ray diffraction data from several proteins have been collected 

at NSLS beamline X12C. Resolution extending to 1.7 Angstroms was achieved for 

small ( less than 100 micron ) crystals of novel human cysteine protease, bacterial 

tRNA-synthetases, and viral proteases. Two derivative data sets at 2.8 Angstroms 

were collected at the Pt and Hg edges to enhance the anomalous scattering signal 

from crystals of a novel human lipase whose structure is now being determined from 

this data. 

The structures of these proteins are important to drug design efforts in our lab- 

oratories. This high resolution diffraction information was not accessible using 

laboratory radiation with the size crystals available. 

I Crystal Structure of Crosslinked Fragment D frorn Human Fibrin * I X12C I 

G. Spraggon, S.J. Everse and R.F. Doolittle (UCSD) 

One of the longest lingering goals in all of blood coagulation research is to understand 

how fibrinogen units are packed together in fibrin clots. In this regard, the 

covalent dimer of fragment D known as "double-D" has been isolated frorn human 

fibrin, and crystallized in the presence of a Gly-Pro-Arg-Pro-amide peptide ligand 

simulating the donor polymerization site. These crystals belong to the monoclinic 

space group P21 with unit cell dimensions: a=93.82, b=05.5, c=113.76. 0=96.08". 

An 88.8 percent complete data set to 2.9~ was collected at beamline X12C of the 

NSLS. A molecular replacement solution was found using .- a - partiallv refined model 

of fibrinogen fragment' D. 

The 170-kilotlalton, end-to-end structure reveals the vrincivle noncovalent interactions 

between fibrin monomers, including the "knob-11ole"~interactions between 

Gly-Pro-Arg and the key residues in the binding cavities on the y domain, and 

the "D-D" interactions of abutting molecules. The covalently crosslinked carboxylterminal 

segments extend frorn one unit to the next on the opposite side of the 

fibrin tlimer to the "knob and holes". These exterrlally situated segments are not 

clrnrly tlclineatetl, indicating that there is some flexibility even after crosslinking. 

(G. Spraggon, S..J. Everse arid R.F. Doolittle (1997) Nature 389:455-462.) 

Figure 1. Ribbon representation of the double-D fragment of human fibrin. Color 

scheme: blue. a-chain: green. $chain: red. ?-chain. (Figure produced with BOB- 

SCRIPT.) 

* This work was supported by SIH Grant HL-26873 and a postdoctoral fellowship to 

SJE from the American Heart -4ssociation. California -4ffiliate.

Atomic Structure of an ap T Cell Receptor (TCR) Heterodimer in 

Complex with an Anti-TCR Fab Fragment Derived from a Mitro- 

genic Antibodv 

X12C 

J.H. Wang (Dana Farber Cancer InstIHarvard), K. Lim (AECOM), A. Smolyar, 

M.-k. Teng, J-h. Liu, A.G.D. Tse, J. Liu, R. E. Hussey, Y. Chishti, (DFCI), 

C.T. Thomson (AECOM), R. M. Sweet (BNL - Biology), S.G. Nathenson, (AE 

COM) H.-C. Chang (DFCIIHarvard), J.C. Sacchettini (AECOM) and E.L. Rein- 

herz, (DFCIIHarvard) 

Each T cell receptor (TCR recognizes a peptide antigen bound to a major histo- 

compatibility complex (MHC 1 molecule via a clonotypic c@ heterodimeric structure 

(Ti) non-covalently associated with the monomorphic CD3 signaling components. A 

crystal structure of an a@ TCR/anti-TCR Fab complex shows an Fab fragment de- 

rived from a monoclonal antibody (mAb) interacting with the elongated FG loop of 

the C/3 domain situated beneath the P domain. This loop, along with the partially 

exposed ABED P-sheet of CP and glycans attached to both CP and Ccr domains, 

forms a cavity of sufficient size to accommodate a single non-glycosylated Ig domain 

such as the CD3.5 ectodomain. That this asymmetrically localized site is embed- 

ded within the rigid constant domain module has implications for the mechanism 

of signal transduction in both TCR and pre-TCR complexes. Furthermore, qna- 

ternary structures of TCRs vary significantly even when they bind the same MHC 

molecule, as manifested by a unique twisting of the V module relative to the C mod- 

ule. These data are the first to define the rigidity of the constant domain module, 

suggest the basis of structural interaction of the CD3c signaling component with 

the TCR heterodimer, and define quartenary structural differences among TCRs. 

The use of beamline X12C was ideal for our crystallographic problem as the co- 

complex crystals were too small for conventional X-ray sources, the nnit cell was 

of significant size with two complexes of TCR-Fab per asymmetric nnit, and at- 

tempts to obtain conventional heavy atom derivatives for isomorphons replacement 

was unsuccessfnl. Consequently based on Friedel flip geometry, we collected data 

on a single splenomethionine substitute of frozen crystal at the inflection point, 

peak point and remote point. The integrated data sets were local-scaled together 

to obtain accurate dispersive differences. Difference-Fourier maps were calculated 

using the initial phases from the preliminary refined model derived with molecular 

replacement. Nine out of 12 Se sites showed up in both anomalous and dispersive 

difference maps, and the sites agree with the methionine positions in the model. 

The MAD data were treated as a special case of multiple isomorphous replacement 

and the nine Se sites were refined and used for phasing. 

Characterization of Fe Impurities in A1N Using EXAFS a I X14A 1 

T. C. Bruss, S. T. Misture and J. A. Taylor (Alfred U.) and T. R. Watkins (ORNL) 

Aluminum nitride is of great interest in the field of electronic ceramics due to its 

unique combination of a high thermal conductivity and a high electrical resistivity. 

Direct nitridation of A1 is a low cost alternative to traditional sol-gel processing. 

However, this processing technique typically produces A1N powders with Fe impuri- 

ties which originate in the A1 metal. Metallic impurities have a detrimental effect on 

the aforementioned properties. A first step in removal of these impurities is identi- 

fication of the chemical state of the impurities. Since the impurity levels are rather 

small (i500 ppm), X-ray diffraction techniques from laboratory instruments were 

unable to detect Fe or any Fe containing compound, possibly because the phase is 

amorphous. 

Extended X-ray Absorption Fine Structure (EXAFS) is a powerful technique 

for identification of phases and compounds containing a specific element as well as 

determination of the local structure (short-range order) about a given atomic center 

in all states of matter. EXAFS has been used to detect Fe impurities in silicon 

nitride and Ti impurities in AlN, for example. EXAFS analysis and absorption 

edge positions were used to unambiguously determine that metallic iron is present 

in A1N produced by direct nitridation. Based on these results, vapor-phase acid 

leaching was used to remove the Fe without significant degradation of the A1N. 

* Research sponsored by the U. S. Department of Energy, Assistant Secretary for 

Energy Efficiency and Renewable Energy, Office of Industrial Technologies, Indus- 

trial Energy Efficiency Division and Advanced Turbine Systems Program. Research 

facilities sponsored by the Assistant Secretary for Energy Efficiency and Renewable 

Energy, Office of Transportation Technologies, as part of the High Temperature 

Materials Laboratory User Program. Oak Ridge National Laboratory is managed 

by Lockheed Martin Energy Research Corp. for the U.S. Department of Energy 

under contract number DE-AC05-960R22464.

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'sasqd aq? 30 OM? leql pa1eaaa.I amq sluaur!ladxa uo!l~qpp Lm-x .sauqIu ypq 

u! paAlasqo sawqd jo suo!slaA Ieuo!suaur!p 0~1% ale saseqd aql 30 Lue~y waBe!p 

awqd xa1duro3 e amq a3qx33u! .~alen\/.~!e aql le spp D!oueyIe jo s~aLqouo~~

C1 

Structural Determination of the CGo/Ge(lll) Interface via X-ray 

X14A 

Diffraction 

T. Kidd, H. Hong, T.-C. Chiang (U. of IL, Urbana-Champaign), R. D. Aburano 

(Cypress Semiconductor), and T. Gog (Argonne Nat. Lab) 

An x-ray diffraction study was performed to determine the nature of the 

C6o/Ge(lll) interface formed by depositing C60 on a Ge(ll1)- c(2x8)surface at 

room temperature. In-plane k-scans show a (1x1) periodicity at the C6o/Ge(lll) 

interface with no trace of the ~(2x8) reconstruction, indicating that the Ge adatoms 

on the clean ~(2x8) reconstructed surface are displaced. Scans along the (10) crystal 

truncation rod indicate that these adatoms are transferred from the Tq bonding 

site to the H3 site after C60 deposition. A model consisting of three relaxed bilayers 

of Ge and randomly distributed adatoms in the H3 site best explains the results. 

: c:; 

: 'i, F j 

c', -8'. 

Figure 1. (a) Top view of (2x2) unit 

cell uncluding uppermost atoms from the 

model model used to fit x-ray intensitiec 

along the (10) rod 

I (reciprocal lattice units) 

Figure 2. Intensity distribution taken 

along the (10) rod. The dashed indicates 

model with in bulk positions. Solid line 

represents model with adatom coverage 

and positions. 

Anisotropic Behavior and a Second Length Scale in the Critical Dif- 

fuse Scattering from the Tricritical System V2H + 

J. Trenkler, P. Chow, S. C. Moss (U. of Houston), R. Paniago (U. of Munich), J. 

Bai (U. of Illinois), and R. Hempelmann (U. des Saarlandes) 

The tricritical behavior of a single crystal of V2H at the P1-Pz-phase transition 

has been studied by x-ray scattering. Critical diffuse scattering (CDS) in alloys 

is a major tool for studying critical phenomena since the diffuse scattering data 

give valuable information on the behavior of thermodynamic parameters like the 

correlation length and the susceptibility at a phase transition. The sharp increase in 

long-wave fluctuations of the order parameter near the critical range causes a strong 

increase in the diffuse scattering of x-rays which directly reflects the thermodynamic 

behavior in this critical regime. 

In this experiment, we mainly focussed on the measurement of the temperature 

dependence of the CDS above Tc, taking line and area scans in order to deduce 

the tricritical exponents y and v from their "deconvoluted" amplitude and half 

width at half maximum of the intensity profiles. The sample exhibits a strongly 

anisotropic CDS in the (Ah, 5/2+Ak, 512-Ak) plane measured at T=Tc+l.O K as 

shown in fig. 1. Thereby, the correlation length is one order of magnitude larger 

perpendicular to the hydrogen (H) sheets than within the occupied H-sheets. An 

analysis of the data is still in progress. 

Furthermore, we observed a remarkable change in the line shape of the critical 

diffuse scattering in the longitudinal [0 1 11 scan at T=Tc+6.2 K as shown in fig. 

2. The measured profile consists clearly of two components, a broad and a narrow 

one, for temperatures T>Tc+6.2 K. At T=Tc+7.3 K,-the narrow component is 

very weak. The higher order superstructure peak (0 712 712) measured at the same 

temperature displays the broad component more prominently than the low order 

superstructure peak (0 512 512). However no change in the line shape was observed 

in the 1 0 01 transverse scans. Further investigation - of this issue was done at X18A 

and ~ i7~1.' 

*This work was supported by the NSF on DMR92-08450 

-0 06 

Resolution 

-0.06 000 0.06 0.12 0.18 0.24 

q - [I 0 01 [IIA] 

O 1 . , . , . 1 ~ ~ ~ ~ ~ ~ 

Figure 1. CDS around the (0 512 $12) 67.5 69.0 70.5 72.0 73.5 75.0 

2 0 

superstructure reflection in a heating run 

in- the (Ah,5/2+Ak,5/2-Ak) at 

T=Tn+l.O K: this data has not been Figure 2. CDS at the (0 512 $12) pocorrected 

for resolution. The cross cor- sition in a heating run in [0 l i] at 

responds to the FWHM of the resolution T=Tc+6.2 K, demonstrating two length 

function. scales.

I High Temperature Residual Stress hlleasorement in Thermal Barrier 1 Xl4A 1 

Coatings* 

T. R. Watkins and C. R. Hubbard (ORNL) 

Thermal barrier coatings (TBC's) are currently utilized in aircraft and diesel 

engines to prolong the life of metallic components. TBC failure is typically spallation 

of the top coat due to oxide scale growth at the bond coat/top coat interface. 

Understanding the residual stresses of the oxide scale growth is thus critical to 

enhancing the performance and reliability of TBC systems. 

In this study, preliminary characterization of the resiclual stress state in the bond 

coat, scale, and substrate was performed. The residual strains are measured in a 

thermally grown oxide scale antl in a PtAl bond coat on top of a Reni N5 superalloy 

substrate at 1150 0C via x-ray diffraction. Large cornpressive residual stresses (i- 

4 GPa) in the the 2 5m thick alumina scale were observed at high tmperature. 

't't~e resitlual stresses decreased at room temperature to -3 GPa, presumbalv due to 

cracking. Fnture experimental work is planned. 

*Research sponsored by the U. S. Department of Energy, Assistant Secretary for 

Energy Efficiency and Renewable Energy, Office of Ir~tlustrial Tecln~ologics, Inc111strial 

Energy Efficiency Division arlcl Advanced Turbine Systems Prograrr~. Research 

facilities sponsored by the Assistant Secretary for Energy EfFiciency ard Re~lcwabl~ 

Er~ergy, Ofice of Transportation Technologies, as part of the High Ternperatwe 

Slaterials Laboratory User Program. Oak Ridge National Laboratory is managed 

by Lockheetl 11artir1 Energy Research Corp. for the U.S. Department of Er~crgy 

under contract n~~rr~bvr DE-AC05-96OR224i.1. 

Surface Structure of Zn2+ Adsorbed on Calcite (10i4) Surface ' I X15A 

L. Cheng, M. Bedzyk (ANL and Northwestern U.), N.C. Sturchio (ANL) : and J.C. 

Woicik (NET) 

Divalent metal ions dissolved in aqueous solution interact with ionic mineral sur- 

faces and frequently become adsorbed on the surafce as a result of this interaction. 

This process effectively acts as a natural means of metal ion transport from the solu- 

ble to the solid phase. ancl has significant implications in fields such as geochemistry 

and environmental sciences. 

Zinc (11) ion (zn2+) is a typical divalent ion, as is calcite (CaCO3) an abundant 

mineral on Earth. The interaction of Zn with the calcite (1074) cleavage surface 

has been a system of rather popular studies [I], in order to obtain quantitative 

data for use in interpreting geochemical antl er~virornnental processes. But a crucial 

component of these quantitative data-the adsorption structure of Zn on calcite- 

has not been directly observed at the atornic Icvcl. 

IVe have conclucted a combined X-ray starding wave (XSW) triangulation and 

surface-polarized EXAFS study on the structure of Zn ion atlsorbccl on the calcite 

(10i4) surface from a dilute (lopR hI) solution. The XSiV triang~~lation res~~lts 

show a high adsorption coherent fraction, of about 0.7, ard the coherent positions 

Pcf have the following values: 

Rtflection Plane Coherent Position 

H PH 

1074 0.87 f 0.01 

0006 0.45 f 0.05 

0324 0.85 f 0.03 

These positions indicate that Zn snbstitutes the Ca ion on the surface. but at 

a lattice position that is tlisplac~tl appreciably from the ~n~tlistorted Ca site. The 

SEXAFS data on Zn show that the Zn-O nearest-neighbor bontl lerlgth on the 

adsorption surface is 2.10 rt 0.02 A. This value is within experimental uncertainty 

comparable to the Zn-0 bontl length in bulk Z~COR. which is isostr~~ctl~ral with 

calcite. The cornbinetl interpretation of thesc SSIV tria~~gulation ancl SEXAFS 

rcsults is that the 0 atoms bonding to the ZII ion. both in-plane a11el in the mormlayrr 

below, collapses to\vartl the Zn ion. 

[I] .T.lI. Zachara et. al. Sorption of tlivalent rr~etals on calcite. Geochim. Cos- 

mochim. Acts. 55. 1549 (1991). 

1hrk was supported by DOE BES contract Yo. 11--31-109-ENG-38 to ;\SL.

Polarity Determination of GaN Thin Films on Sapphire(0001) by 

X-ray Standing Waves 

X15A 

A. Kazimirov, G. Scherb, J. Zegenhagen (Max-Planck-1nst.-FKF, Stuttgart, Ger- 

many), T.L. Lee (NWU), M.J. Bedzyk (NWU and ANL), M.K. Kelly, H. Angerer, 

0. Ambacher (Walter-Schottky Inst., TU-Muenchen, Garching, Germany) 

Thin films of the wide-bandgap semiconductor GaN are important because of 

their application for short-wavelength, light-emitting LEDs and lasers. In the (0001) 

crystallographic direction, the non-centrosymmetric wurtzite GaN crystal exhibits 

no mirror symmetry for the Ga and N atomic planes. As a consequence, for thin 

films on e.g. sapphire there are two possible stacking sequences. We applied X-ray 

Standing Wave technique [l] to determine the polarity of thin GaN films grown 

by MBE on Alz03 single crystals. Different from the standard approach based on 

the excitation of an XSW field inside a perfect single crystal, we generated an X- 

ray standing wave by the thin GaN film [2] by X-ray diffracting 10.5 keV photons. 

The Ga-K, fluorescence yield was measured as a function of the incidence angle 

within the range of the GaN(0002) reflection. The experimental result for the lpm 

thick film is shown in Fig.1. The convolution with a Gauss function (u=0.05 deg.) 

was used to take into account the broadening of the reflectivity curve due to some 

growth defects. The static Debye-Waller factor describing the perfection of the film 

structure was used as the only fitting parameter (Fig.2). Our results unambiguously 

indicate N-polarity of the MBE grown film (nitrogen atoms occupy the top half of 

the bilayer) with the static DW-factor e-W ~0.36. This finding is in contrast with 

the result of a recent ion-channneling and electron diffraction study for the polarity 

of thin films on sapphire grown by MOCVD 31. 

1 J.Zegenhagen, Surf. Sci. Rep. 18 (19931 199. 

121 A.Kazimirov et al., Acta Cryst. I348 (1992) 577; A.Kazimirov et. al., Solid 

State Comm. 104 (1997) 347. 

[3] B. Daudin et al., Appl. Phys. Lett. 69 (1996) 2480. 

1.010 

GaN lpm thick MBE film on A1203(0001) 

experiment 

. . . . . . . . Ga-polarity 

N - polarity 

( 4 Ga-polarity / 

0.985! , . , , I . , . , I , . , . , . , . , 

-0.4 -0.2 0.0 0.2 0.4 0.1 0.2 0.3 0.4 0.5 0.6 

angle, deg. 

static DW-factor 


1 Dimer Structure of Sb-Terminated GaAs(001)-(2x4) Surface * I X15A 

T.-L. Lee (Northwestern U.) and M.J. Bedzyk (Northwestern U. and ANL) 

The bonding geometry of the GaAs(001):Sb-(2x4) surface was investigated by the 

x-ray standing wave technique (XSW) using the (004) and (022) Bragg reflections. 

The height above the surface (h') and the bond length (L) of the Sb dimer were 

measured to be 1.72 Aand 2.84 A, respectively, in good agreement with the previous 

theoretical calculation [l] and other measurements on related surfaces. The Sb 

coverage of the (2x4) reconstruction was determined by Rutherford back scattering 

to be 0.48 ML, consistent with a model having two Sb dimers per unit cell. We then 

considered two previously proposed structures of a half ML coverage (see figure): 

one with two Ga dimers in the second layer (Model I), and the other with one As 

dimer in the third layer (Model 11). Theoretical calculation [I] has shown that both 

structures are energetically stable. We discriminated between these two models by 

measuring the lateral displacement (Ax) of the Sb dimers, which is expected to be 

much larger for Model I due to the formation of the Ga dimers. Our (111) XSW 

measurement revealed a negligible lateral shift and is therefore in favor of Model 11. 

[l] N. Esser, A.I. Shkrebtii, U. Resch-Esser, C. Springer, W. Richter, W.G. 

Schmidt, F.Bechstedt, and R. Del Sole, Phys. Rev. Lett. 77, 4402 (1996) 

[O0'1 

kr 

[Ill] 

i lo] 

[I io] 

Model I 

\ \ \ 

(I 1 1 ) planes 

Figure 1. 

Model II 

* This work was supported by the NSF under contract No NMR-9632593 and DMR- 

9632472 to theMRC at Northwestern U., and by the US DOE under contract No. W-31- 

109-ENG-38 to ANL.

In-Situ X-ray Standing Wave Analysis of Electrodeposited Cu Mono- 

layers on GaAs(001) 

- - 

J. Zegenhagen, G. Scherb, A. Kazimirov (Max-Planck-1nst.-FKF, Germany), H. 

Nogushi, K. Uosaki (Hokkaido U., Japan), T.-L.Lee (NWU), and M.J. Bedzyk 

(NWU and ANL) 

Electrochemical preparation of surfaces is very attractive with the drawback that 

the majority of the surface characterization tools which are available e.g. for UHV- 

preparation are not applicable because of the presence of the electrolyte. X-ray tech- 

niques are an exception and have been employed increasingly for investigations of 

metal/electrolyte interfaces. Little work has been done for semiconductor electrodes 

despite its importance and the scarse information about corresponding structural 

processes. Recently we reported the first in-situ X-ray structural analysis of this 

kind employing X-ray diffraction [I]. We studied GaAs(001)/HzS04 as a function of 

electrode potential and the growth and epitaxy of Cu clusters [1,2]. The first in-situ 

XSW study of a semiconductor electrolyte interface for GaAs(OOl)/HzS04(:Cu) is 

presented here. The GaAs(004) reflectivity and the Cu-K fluorescence yield for 0.6 

ML electrodeposited on n-GaAs(001) are shown in the figure. The result shows 

that (sub)monolayer amounts of Cu adsorb predominantly substitutional before 3- 

D clusters start to grow. Part of the Cu diffuses a few ten nm into the bulk in an 

amount different for p- and n-type GaAs. Coherent fractions are always smaller 

than 0.4, showing that other minority positions are occupied by the CLI. Even if the 

GaAs is anodically dissolved, the surface Cu is removed only slowly, proving that 

it is strongly bound to the GaAs within the top surface layers, staying at/within 

the surface even if it is slowly etched away. 

1 J.Zegenhagen et al., Surf. Sci. 352-354 (1996) 346. 

2 D.-M.Smilgies et al., Surf. Sci. 367 (1997) 40. 

t 1 

u - 0.6 ML CU 

a, 

.- N - - FzO.39 +- 0.03 

.5 7 P=0.94 + 0.02 

s 

C .- 

cn 

s 

a, 

0.5 Refl. 

- 

Figure 1. 

CU-K, 

GaAs (004) 

I Fundamental Limit Of Free-Carrier Densities In n-doped Si I ~ 1 4 

D. J. Chadi, C. H. Park (NEC), D. L. Adler, M. A. Marcus, H.-J. Gossmann, and 

P. H. Citrin (Bell Labs) 

A critical factor in the evolution of increasingly small Si-based components is the 

maximum achievable free-carrier concentration. Electron carrier densities in n-type 

Si are observed to saturate at

I X15B 

P. A. Northrup, R. All. Atkins, P. F. Glodis, D. C. Jacobson, and P. H. Citrin (Bell 

Labs) 

w 

N Trace Metal Contaminants in Optical Silica Preforms 

3 

The greater transmission losses measured from certain optical silica fibers had 

been shown by us last year to correlate with the existence of particular metal impu- 

rities in the cores of the parent preforms. Surprisingly large amounts of Fe (> 100 

ppb) were even found in a fiber preform that had a much lower loss. The results 

raised concerns about the reliability of the absolute metal concentrations and about 

the purity of the starting tube itself (suppliecl by an outside vendor). A new series 

of calibration standards was therefore studied, and a thorough re-examination was 

made of two preforms whose fibers yielded very different losses. These more accu- 

rate Fe measurements strengthened the conclusions of the earlier study, including 

the fact that the Fe exists almost exclusively in the relatively benign 3+ state (the 

concentration of the more absorbing Fez+ species is experimentally obscured by - 

and clearly scales with - the amount of Fe"' present). Extension of measurements 

into the outermost shell region showed that the metal impurities do not originate 

from the starting tube. This was further confirmed by a study of Cu impurities, 

whose concentration clepentlence on position and optical loss was essentially iden- 

tical to that for Fe. The striking spatial variation in metal concentration that was 

observed suggests the origin of rnetal contamination in the preform manufacturing 

process. 

I Structural Stability of Vacancy-Ordered Rare-Earth Fulleride I X15B I 

K. N. Rabe (Yale) and P. H. Citrin (Bell Labs) 

Superconducting Yb2.75C~o is unique among metal-doped fullerene compounds, 

exhibiting long-range-ordered vacancies, significantly displaced Yb cations (2.4 A). 

inequivalently charged and distorted Cso anions, and rotationally ordered C60 pen- 

tagonal faces. A simple electrostatic-enera analysis was used to explain how each 

of these features stabilizes this apparently exotic crystal structure (2008 atoms/unit 

cell). The results have genera1 implications for other, more conventional intercalated 

metal fullerides.

I Formation of Comer Silicide usinn Surface X-ray Diffraction * I X16A I 

P. Bennett (ASU Physics), I. Robinson and D. Walko (UIUC Physics) 

We report an in-situ study of the initial stage of copper silicide formation during 

deposition of Cu on Si(ll1) at 300K using surface X-ray diffraction. The practical 

significance of this system stems from its importance in the VLSI microelectronics 

industry. From a scientific viewpoint, it is interesting to study how an epitaxial 

overlaver forms in a large-misfit system ICu(ll1) is 5% larger than a RT3 coincidence 

lattice on Si(lll)]. - 

L . , 

Walker reported in an ex-situ X-ray diffraction study that a lOOnm film of Cu on 

Si(ll1) contains a buried monolayer of commensurate CusSi, strained 7% to match 

the substrate. On the other hand, Bootsma reported that only incommensurate 

silicide forms, based on an in-situ study using RHEED and AES. 

We find that the first few M1 of copper forms commensurate Cu3Si. This is clear 

from the CTR scan (integrated intensities at points along the substrate trunca- 

tion rod) shown in the figure (LHS). The new peak near L = -4 corresponds to 

islanded but commensurate CusSi. Additionally, the overlayer contributes a char- 

acteristic +/- asymmetry near the substrate Bragg peaks (L=+l, +4), from which 

the overlayer registry may be determined (work in progress). At higher coverage, 

the coherent silicide structure is mostly consumed. Incommensurate copper metal 

forms at the same time, as evidenced by the incommensurate rod scans Q = (1.65, 

1.65, L) shown in the figure (RHS). It is remarkable that this structure begins as 

hcp Cu (peak near L = 2.2), before adopting the fcc structure (L = 2.2), with 

marked twinning (L=3.0) 

In conclusion, we find that in-situ monitoring of the initial stage of copper silicide 

formation reveals two "transient" structures that might strongly affect the formation 

of thicker overlayers. 

w 

t\3 

w * Supported by NSF grant MR9528503. 

moo 4 

- 

Figure 2. 

I Ultra-High Doping in Si(001): B Pairing and Diffusion 1 Xl6A 1 

G. Glass, I. K. Robinson, D. Walko, and J. E. Greene (U. of Illinois) 

Ultra-high B doped Si and Si(1-x)Ge(x) films have the potential to drive fur- 

ther miniaturization of microelectronics with minor changes in process technology. 

Some applications for such layers include sourceldrain regions in MOS transistors, 

base layers in SiGe HBT's, and emitter layers in BJT's. Ultra-highly B doped 

films on Si(001) have generated considerable scientific interest as a tensile strained 

layerllimited miscibility system. Ultra-high B doped Si(001) samples were grown 

by Gas-Source MBE to a Cg of 2x10'~ cmP3. The B was determined to be electri- 

cally activated from a combination of SIMS and Hall-effect measurements. Samples 

were isothermally annealed in-situ under high vacuum conditions in X16A, at tem- 

pertures in the range of 900 to llOO°C until the strain was reduced to 10% of the 

initial value. The experimental curves show a rapidly decaying separation between 

the film and substrate (004) peaksas seen in Figure 1. Two exponential terms were 

needed to fit the data. SIMS measurements after annealing showed B diffusion from 

the film into the bulk. All films remained coherent, and no precipitates nor mis- 

fit dislocations were found by XTEM. Ab initio psuedopotential calculations were 

performed by Zhu* et. al. which revealed that a boron pair on a single Si lattice 

site is a stable configuration for B in Si. The predicted volume of a cell containing 

a boron pair bonded to four Si atoms is larger than a pure Si tetrahedron, and 

therefore would tend to increase the lattice constant of the film. The goal of this 

experiment was to demonstrate the Arrheneius behavior of the B pairing reaction, 

and to obtain activation energies for the formation of such pairs. Preliminary results 

in Figure 2 show the activation energy for the first exponential term attributed to 

the formation of B pairs to be 1.6 eV. The second activation energy attributable 

to diffusion is 2.9 eV. This value is lower than the 3.4 eV value typical for lower B 

concentration material. but it is reasonable considering that B diffusion is enhanced 

at high concentration. '*J. Zhu et al, Phys. Rev. B, 52, 4741 (1996). 

Annealed @ 1000 'C 

0 2 4 6 8 1 0 1 2 

0.90 0.95 1.00 1.05 1.10 1 

,P? Time (hours) 

1 OOOrr (K.') 

Figure 1. Separation between the 

Si(004) and Si:B(004) peaks as a func- Figure 2. Arrhenius behavior of the two 

tion of time at 1000 C. Two exponential strain reducing mechanisms as a functerms 

were used to obtain a good fit. tion of 1/T.

P I Irradiation Induced Strain Relaxation of a Metastable SiGe Film 1 X16A I 

F 

h3 

w C. Kim, T. Spila, J. E. Greene and I. K. Robinson (U. of Illinois) 

When SiGe alloy is grown on Si(001), there exists a critical thickness below 

which the SiGe film can be grown pseudomorphically. The theoretically predicted 

critical thickness using equilibrium theory is, however, smaller than that measured 

by experiment because of kinetic effect. A metastable film can therefore exist when 

its thickness is in the range between the theoretically predicted and experimentally 

determined critical thicknesses. Since it is not in the state of energy minimum, it 

might be possible to have the strained film relax by external pertnrbation such as 

irradiation. 

In ow experiment, a metastable SiGe film of 200 A grown at 500 O C was irracli- 

atecl with 25 KeV Ga ions in a UHV chamber combined with a diffractometer and 

strain relaxation was measured in-situ. The dose ranged from 8x 10" to 3.6~ 10''' 

(ions/cm2). Substrate Si unit cell was chosen for indexing Bragg peaks antl As 

shown in Fig.1, a series of index scans through (202) peak of SiGe were made for 

different doses of irratliation. The maxima of sharp peaks the to coherent tliffraction 

decreased as we increased dose. On the other hand, the intensity of diffuse 

scattering mas obervetl to increase. In Fig. 2, the tliffusc scattering alone is shown 

on a linear scale by subtracting the rriairi peaks from the raw data. It is clearly seen 

that tliffi~sc peaks shifted with increasing tlose. The peak shift can be attributed 

to the misfit dislocations induced by irradiation and is one good evitlcnce of strain 

relaxation of metastable SiGe film. 

The peak position antl witlth convey information about the changes in microstructure 

of the film during irratliation. For example, the increase of lattice constant with 

more tlose is related to the increase of average tlislocatiou distance. In the meanwhile, 

peak witlth, which is inversely proportional to a. domain size, tlecrcasrtl as a 

fnnction of tlose. Therefore. if we asstnrlc the donlain size is tletrrminetl by average 

distance between dislocations, information obtained frorn shift of peak position antl 

width is consistent with each other. 

Figure 1. =\ series of index scans along h 

Figure 2. Diffuse scattering intensities 

for doses of rote 

direction through SiGe (202) peak after that the nlain peaks

W 

I X-ray Investigation of a Sio.g, Gee, (001) Single Crystal Surface I X16A I 

H. Reichert (U. of Wuppertal, Germany), S.C Moss (U. of Houston), C.Y. Kim, 

and K. Evans-Lutterodt (Lucent Technologies) 

We have investigated the near surface structure of a Sio.gGeo.l(OO1) single crystal. 

During the cleaning procedure we have performed reflectivity measurements in order 

to monitor the Ge concentration profile in the near surface region. After cleaning the 

surface chemically we found a large Ge excess concentration which can be deduced 

from the oscillations of the reflectivity curve in Fig.1. We have also studied the 

intensity distibution along integral order crystal truncation rods at this stage of the 

sample preparation. 

Following a short heating treatment at 850°C the quality of the crystal surface 

degrades quickly. This can be seen by the change in the reflectivity profile in Fig.1. 

Further heating at 850°C for prolonged times changes the surface morphology in 

a characteristic way. Fig.2 shows a scanning electron micrograph of the surface 

after the annealing procedure. A large number of pyramidic holes formed at the 

surface. The size of the holes depends on the highest temperature reached during 

the heat treatment. The specular reflected intensity is strongly damped while the 

off-specular diffuse intensity is increased and structured. 

Figure 1. Reflectivity bevor annealing 

(open circles), after annealing at 850' C Figure 2. Scanning electron micrograph 

for 30 min (filled circles), and after an- of the Sio.~Ge0.1(001) 

- - - - surface after annealing 

at 8500~ for 8 h' (triangles). nealing. 

Evolution of 0-Induced Facet Formation on Cu(115) 

D.A. Walko and 1.K Robinson (Univ. of Illinois) 

We have observed the evolution of the Cu(115) surface during dosing of oxygen. 

This surface breaks up into three facets after 0 exposure, whose orientations cor- 

respond to (104), the symmetry equivalent (014), and (113). We investigated the 

dymanics of facetting as well as the static structure of the final surface. 

After dosing the Cu(115) surface with several Langmuirs oxygen, the crystal 

truncation rod corresponding to this surface begins to decay. Rods corresponding 

to the (104) and (014) facets appear, but the (113) facet does not form immedi- 

ately. Instead, steps proliferate on the (115) facet and its average orientation slowly 

changes from (115) to (113). This is seen in Fig. 1 for facetting at two different 

temperatures. Fig. 1 shows a series of scans passing thru the (115) and (113) facet 

positions (at h=6.0 and h=6.282, respectively). These scans are 0.8k1 below the 

bulk (111) Bragg reflection. 

Fig. 2 illustrates the qualitative difference of facet formation above and below 

T%310°C, by displaying facet peak position from Fig. 1 as a function of dose. 

Above this temperature, the peak slides continuously from the (115) to the (113) 

position. Below T%310°C, the peak slides about halfway from (115) to (113), then 

jumps to the (113) position. Apparently, at these lower temperatures, a particular 

range of facet orientations is thermodynamically unfavorable. 

Once the surface was completely facetted, x-ray surface crystallography measure- 

ments could be performed on the individual facets. The (104) facets did not show 

any superstructure, but a 3x1 reconstruction was found on the (113) facets. A 

structural analysis of the surfaces is in progress. 

Figure 1. Scans thru the (115) and 

(113) facet rods, as a function of time 

during exposure to 02. As Oz dosing 

progresses, the peak moves from left to 

right. a) T=340°C, PO, =4x lo-' mbar. 

b) T=260°C, PO, =l x lo-' mbar. 

X16A 

Figure 2. Facet positions (in reciprocal 

lattice units) as a function of 0 dose. a) 

T=340°C; b) T=260°C.

P 

+ I Superstructure Ordering in La Doped PhlN Single Crystals 1 Xl6C 

to 

rp D. h1. Fanning, S. T. Jung, D. A. Payne, I. K. Robinson (U. of Illinois-UC) 

Lead magnesium niobate (Pb[Mglj3Nb2/3]03) is a classic ferroelectric relaxor, 

having a very high, frequency dependent dielectric constant near room temperature. 

It has the perovskite structure. and the mixed B-site is believed to be responsible 

for its broad transition to the paraelectric state. 

Previously [I], we studied pure PhIN crystals and found superstructure reflections 

at the (h+1/2. k+1/2, 1+1/2) positions. These were shown to be the result of 

chemical ordering between the h'lg"' and ~b'+ ions. The ordered regions were 

measured to be about 50 in size. It is believed $hat their size is limited clue to the 

non-stoichiometric 1:l ordering of hIg" and Nb"+, which results in an average net 

charge of -0.5e per unit cell. By doping with ~ a in ~ place + of pb2+, it is possible 

to increase the size of the ordered region. In this experiment, we studied the effects 

of this increased ordcring and the feasibility of using La doped PhIN for a coherent 

XRD study. 

Single crystals of La-PkIN were grown by the flux method. For each crystal,we 

measured about 100 superstructure rcflcctions. \i7e found the crystal quality was 

quite good, with no mosaic structure. By averaging the widths of the superstructure 

reflections. we cletermir~ecl thc size of the cl~emically ordered region using the 

Scherrer formula. As expected the size i~lcrcases with La concentration: to 130 A 

for 4.5% La-PLIN, antl 1000 A for the 10% La-PAIN. 

\Ve were able to determine the str~~ct~~re of the ordered region by fitting to our 

model (Figure 1). We assurue nearest neighbor unit cells havc different B-site ions. 

alternating between Alg"' arid Nb"+. The oxygen atom posit,ions are free pararncters 

that displace towards the smaller ~ b " ions (ratlil~s of O.(i5 A vs 0.72 k\ for 

hIg2+). Combined with Debye-\Valler factors. this model was ~~setl to successfully 

fit our data for both pure arrcl La tlopctl PAIN. 

Figure 2 shows the oxygen tlisplacemer~t as well as the measured lattice constant 

for the 3 crystals. Clearly, the trerltl in the oxvgcu displacement and latt,ice parameter 

arc in a consistent direction. \Ye believe that by chemically ordering, PAIN is 

nble to redim the strain caused by the large XIg" ion. 

i\ separate DAFS st,~ltly [2] corlfirms our value for the oxygen displacement in 

pure PNN. 

1 D.AI. Fanning and 1.K. Robinson. NSLS Activity Report, page B-136, 1996. 

I 2 I X.I. Frcnkcl. D.11. Fanning, D.L. :\tiler, .T.O. Cross ;mtl I.K. Robinson, these 

Proceedings. 

. . 

-. b c-mr.,m 

Figure 1. AIodel of chemical ordering of 

Mg and Sb ions with oxygen displace- Figure 2. Best fit oxygen clisplacement 

ments along (100) directions towards Sb. and measured average lattice constant. 

I DAFS Analysis of Local Structure of Ordered Nanodomains in PMN I X16C 1 

A.I. Frenkel, D.M. Fanning, I.K. Robinson (UIUC), D.L. Adler (KLA Instrum.): 

and J.O. Cross (NRL) 

We performed Diffraction Anomalous Fine Structure (DAFS) measurements of 

the single crystal of relaxor ferroelectric Pb[hlgl/3Nb2/3]03 (Ph,IN) which has cubic 

structure at 300 K. Presence of superstructure spots in our X-ray diffraction 

measurements [I] confirmed the existence of 1:l Nb:h#lg ordered nanoclomains in a 

Nb-rich host lattice. Local structure in the ordered domains has been investigated 

before by Nb K edge EXAFS measurements [2] where the task of separation between 

the contributions of the nearest neighbors (NN) to Nb to the total EXAFS 

signal from the host lattice and nanodomains is very difficult. 

DAFS measurements of the peak (-.5, -2.5, 2.5) were taken at the Nb K edge. 

By using a superstructure peak, we were able to look at only the NbNN contributions 

in the ordered ~ianotlomains. Data were nleasuretl using a custom-designed 

4circle Kappa diffractometer and a data acquisition program SUPER. Fluorescence 

background was measured by moving the 20 arm of the cliffractometer to an 

off-peak position. Resultant DAFS data (after fluorescence background was subtracted) 

are shown in Fig. 1. Smooth background intensity was fit to the DAFS 

data using Cromcr-Liberman theory for .ff, antl .f;,' as a first approximation. To 

extract absorption cross-section a(E) and perform standard EXAFS analysis, iterative 

Kramers-Kriinig transforms procedure [3] was applied to isolate true f' and 

f" N E . u(E). Resultant EXAFS fil~lction y(k) was fit with FEFF theory in r 

space (Fig. 2) in tlic region 111ostly contributed by Nb-0 pairs. The Nh-0 tlistarice 

in the orcleretl region was tlctcrmined to be 0.052(5) i\ shorter than half the lattice 

parameter of PAIN, in exc~llcnt agrccmcnt with our diffraction [I] antl previous 

EXAFS results [2]. 

I 

1 

/ 

D.hI. Farming and I.K. Robinson, these Proceedings. 

2 E. Prouzet et al., .J. Phys.:Co~~dcns. AIattcr 5, 4889 (1993). 

3 d.0. Cross, P11.D. Thesis, University of Ihshington. 1996. 

Figure 1. Fluorescence subtracted raw 

D-IFS data (clash) and fit to the back- 

ground (solid). 

Figure 2. Data (dash) and fit (solid) to 

the Sb-0 nearest neighbor shell. Fitting 

range is shom-n by arrows.

In Sztu XAFS Study of Pt-Ru Catalysts in Fuel Cell 1 X16C I 

A. I. Frenkel, M. S. Nashner, C. W. Hills, J. R. Shapley, and R. G. Nuzzo (UIUC) 

Tn our previous work [I] we reported the results of the preparation and charac- 

terization with XAFS of the PtRus bimetallic nanoparticles. In the present work, 

we performed the in situ study of a similar system, PtRu4, in a custom designed 

fuel cell at three different potentials: open circuit, 0.25 and 0.7 V. These potentials 

correspond to different stages in the methanol oxidation process. 

Well-defined Pt-Ru binary particles were prepared from PtzRu4(CO)ls molecular 

cluster precursor. The solution was then dispersed onto a carbon cloth support 

and heated under Hz flow at 400° for an hour. Pt LQ and Ru K edge XAFS data 

(Figs. 1 and 2) were collected in these catalysts in a fuel cell in fluorescence at 80°C. 

Structural refinement was performed simultaneously for the both Pt Lg and Ru K 

edges data using UWXAFS programs. We obtained a non-statistical distribution 

of Pt and Ru atoms in the nanoparticles, consistent with a segregation of the Pt 

particles in the core of the cluster. While the increase of potential from 0 to 0.7 V 

led to the decrease of both Pt-Metal and Ru-Metal coordination numbers (Fig. 3), 

interaction of Pt with low Z atoms (oxygen, CO ligands and C support) was not 

affected by changes in V (Fig. l), whereas the number of Ru-low Z bonds increased 

with V (Figs. 2 and 4). 

[I] M. S. Nashner, A. I. Frenkel, D. A. Adler, J. R. Shapley, and R. G. Nuzzo, J. 

Am. Chem. Soc., 119, 7760 (1997). 

Figure 1. Pt Ls-edge data in R space. 

Figure 2. Ru K-edge data in R space. 

Figure 3. Number of Pt-Metal and Ru- 

Metal nearest neighbors. 

Figure 4. Number of Ru-0 nearest 

neighbors. 

I Evolution of PtRu5C(CO)lc Molecule into a Pt-Ru Nanoparticle I X16C / 

A. I. Frenkel, M. S. Nashner, J. R. Shapley, and R. G. Nuzzo (Univ. of Illinois) 

In our previous work ([I], see also previous abstract), we analyzed the final prod- 

uct - a bimetallic Pt-Ru supported nanoparticle - as obtained from the precursor 

PtRu5C(C0)16 by activation at Hp at 673 K. Here we present the results of in situ 

evolution of the precursor into a bimetallic nanoparticle. 

XANES measurements at Pt L3 edge (Fig. 1) have been performed at different 

temperatures at Ha flow. They correspond to different stages of chemical evolu- 

tion. We found chemical evidence for the loss of CO ligands with temperature as 

evidenced in dramatic reduction in amplitude of the white line as temperature in- 

creases. This amplitude reduction is also consistent with the particle size increase 

with temperature, observed in STEM measurements. We also observed a shift in 

the edge position to lower binding energies resulting from the formation of an in- 

creasingly metallic state with temperature in the presence of HZ. 

EXAFS analysis of Pt Lg and Ru K edge data confirmed the above XANES 

results on the fragmentation of the molecular precursors, loss of the CO ligands, 

and increase of the cluster size with temperature. Over the temperature range 300 

- 473 K, the precursor molecules (Fig. 2, left) aggregate into a cherry-like structure 

with Pt atoms occupying core sites (Fig. 2, center). Upon further temperature 

increase the structure transforms into its final form (Fig. 2, right) with Pt atoms 

preferentially occupying surface sites. 

111 M. S. Nashner, A. I. Frenkel, D. L. Adler, J. R. Shapley, and R. G. Nuzzo, J. 

A&. Chem. Soc. 119, 7760 (1997). 

300 K - Pt 4 edge 

523 K --- 

573 K -- ------ ) \'i _---- 

*. &-=-== 

11550 11560 11570 11580 11590 


Figure 1. Pt Ls XANES during activa- 

tion of the molecular cluster precursor 

under Hz. 

Figure 2. Schematic of the evolution of 

the molecular cluster precursor into a 

bimetallic nanoparticle.

P I XAFS Analysis of Particle Size Effect on Local Structnre of BaTiOs I X16C I 

F 

h) 

o A.I. Frenkel and D.A. Payne. (U. Illinois at Urbana-Champaign) 

The local structure of several samples of BaTi03 prepared by solution-gelation 

method with different particle sizes (less than 0.1 pm) and a sample with - 10 pm 

particle size has been investigated using the X-Ray Absorption Fine Structure 

(XAFS) technique. Although the macroscopic crystal structure changes from te- 

tragonal to cubic at room temperature when the particle size is less than 0.1 pm. 

we obtained that Ti atoms are displaced from the center of cubic symmetry for all 

the samples studied. Both EXAFS (Fig. 1) and XANES (Fig. 2) measurements 

demonstrate that there is no difference in the local structure around Ti for the 

reference sample with a macroscopic particle size (10 pm) where it is known that 

the local strncture is off-centrosymmetric and the samples with d < 0.1 pnl where 

the local strllctnre is nnknown. XANES behavior in the Is -t 3d transition region 

(4965-4970 e\J) is particularly sensitive to the tlispnccments of Ti atoms from the 

center of 0 octahedron [I] (the area under the pcak depe~ds qmclratically on the 

displacement). ant1 our results prove that local tlisplacc~nents are almost the same 

in all the samples studied. 

The existc~icc of different local and macroscopic structures means that the local 

tlistortions from the average structwc arc tlisortlcrctl. This result agrees with 

previous Rarrlan spectroscopy measurernents [2] where the struct,ure ot the samples 

with pxticles srnaller than 0.1 pm was o1)tainctl to he non-cubic. In atltlition 

to prcviousl,v olhi~letl evitlence of a dominant order-tlisortler behavior in this a~ltl 

othcr pcrovskites, subject to ternprratllrc or pressure treatments, this result again 

drmonstratcs that the low syrnrrlet,ry struct~~rc prcscrvcs locally while the average 

str~~ct~~rc cl~ar~gcs during various phasr transitior~s [R]. 

This work was sl~pportetl IF the DOE Graut No. DEFG0296ER45439 throngh 

the llatcrials Research Laboratory at the University of Illinois. 

B. Ravel et al., Ferroelrrtrics, 1997 (in press). 

1I.H. Frey ant1 D.:\. Paynr. Phvs. Rcv. B 54. 3158 (1996) 

i\.I. Frenkel et al., Phys. Rrv. B 56. SSSS (1997). 

< 

- ,b2 

Preparation and Characterization of Carbon Supported Pt-RLI I X16C / 

Nanoparticle Catalysts 

MS. Nashner, A.I. Frenkel. D.L. Adler, J.R. Shapley, and R.G. Nuzzo (UIUC) 

Bimetallic nanoparticles supported on carbon black were prepared from a 

P~Ru~C(CO)~~ molecular cluster precursor by activation at Hz at 673 K [I]. The 

narrow compositional distribution. which was found to be centered at 15 Pt:Ru 

ratio, suggests a uniform coalescence of the precursor clusters upon activation. hlicrotliffraction 

measurements indicate the formation of nanoparticles with an fcc 

microstrnctnre even though the bulk structure for this composition is hcp. The 

nanoparticles undergo reversible oxidation forming a metal-oxide surface and a core 

of metal. The Pt Ls-edge and Ru I.-, I,>,,,, y,q-, 

IYawnumh~~r. .i-I 

Figure 1. k2-weighted y(k) for the samples 

with different particle sizes. 

Photon rilrmqr. r\- 

Figure 2. X=\SES region for the san~ples 

n-ith different particle sizes. 

Figure 1. Bright and dark field STElI 

images showing Pt-Ru nanoparticles 

(spot 1) and carbon-support (spot 2). 

Electron beam size is - lo=\. 

Figure 2. Hisgtogram of the particles 

size distribution (right axis) nleasuretl 

with STElI. -Average coordination nurnber 

as obtained with ESAFS (left axis).

-4 

X-Ray Microprobe Measurements of Patterned InP Multi-Quantum 

X16C 

Well Lasers 

E.D. Isaacs, K. Evans-Lutterodt, M.A. Marcus. A.A. Macdowell, W. Lenhart, 

L. J.P. Ketelsen, J. Vandenberg, S. Sputz, J.E. Johnson and J.A. Grenko (Bell Laboratories) 

We have developed a scanning x-ray microprobe (XMP) on beamline X16C. The 

principal components of the XMP are a horizontally collimating, double Si(ll1) 

crystal monochromator with an energy range from 5 - 20 keV, a pair of glancing 

incidence, elliptically bent mirrors for focusing in the vertical and horizontal, re- 

spectively. The mirrors produce a beam of approximately 3 x 20 pm with a flux of 

10' photons/sec at 8 keV. This represents a gain in flux of 65 over a pinhole with 

the same area. The diffractometer used with our XMP has a detector arm with two 

degrees of freedom and micron sample positioning capability. 

One of the key applications of the Bell Labs XMP has been in the micro- struc- 

tural characterization of laterally patterned opto-electronic devices such as the 

electro-absorption modulator laser (EML). The EML is a monolithically integrated 

InGaAsP multi-quantum well (MQW) laser and electo-absorption modulator which 

has been demonstrated to speeds of 10 Gbitslsec. The EML has a 1 pm wide active 

region and is buried under a few microns of InP. While strain is crucial to the ef- 

ficient operation of the device, too much strain can cause misfit dislocations which 

provide non-radiative recombination centers, fatal to laser operation. The XMP 

is the only probe with which to non-destructively measure the strain in the buried 

EML device. By measuring radial Bragg scans through the MQW superlattice peaks 

at several positions on the EML device (see Figure) we are able to make a spatial 

map of the MQW strain (position of oth-order superlattice peak). This microscopic 

strain map has been crucial in a redesign of the growth masks in order to control the 

strain in the MQW. The Bragg scans also tell us about the MQW period (superlat- 

tice spacing) and composition (relative superlattice intensities). Maps of the period 

and composition have enabled us to more accurately target lasing wavelengths. Ac- 

curate positioning of the wavelengths is becoming more important as wavelength 

multiplexing, requiring many (8, 16, 32, ....) very closly spaced frequency channels, 

becomes the norm in high speed lightwave communications. 

Electlo abromlon 

.,"I ,., a,,. ypw' 

Figure 1. Radial Bragg scans long the InP(004) substrate direction taken at posi- 

tions inside the laser structure (botton line), through the transition region (middle 

four lines) and into the modulator region (upper line) taken with 5 um spatial 

resolution. The variation in MQW period and strain as a function of position is 

observed as a variation in spacing between superlattice peaks (labeled by order) 

and the position of the 0th order peak, respectively. The data are offset for clarity. 

Sound Velocity Measurements at Simultaneous High Pressure and 

Temperature For Polycrystalline San Carlos Olivine 

1 X1'7B11 

G.Chen, Y. Sinelnikov, R. C. Liebermann (SUNYat Stony Brook) and G. D. Gwan- 

mesia, K. Darling (DSU) 

Dense isotropic polycrystalline San Carlos olivine were fabricated at high pressure 

and high temperature in a Girdle-type high pressure apparatus using hot-pressing 

techniques developed previously by Gwanmesia and Liebermann (1992; see also 

Gwanmesia et al., 1993) and crushed natural crystals as starting materials. These 

specimens have bulk densities within 1% of the X-ray density and exhibit compres- 

sional (P) wave and shear (S) wave velocities within 1% of single crystal elastic 

moduli of Kumazawa and Anderson (1969). Recent technological development in 

our laboratory has enabled precise interferometric measurements of elastic wave 

velocities in mienrals to be performed to pressures of 9 GPa and temperatures of 

1500 K in a DIA-type, cubic anvil apparatus (SAM85) interfaced with white X-ray 

radiation from the superconducting wiggler port of the National Synchrotron Light 

Source at Brookhaven National Laboratory (see Liebermann et al., 1997). We have 

performed measurements this important mantle mineral (ultrasonic and X-ray) to 

7 GPa and 800 K.

Equation of State of NaCl From Simultaneous Ultrasonic and Syn- 

chrotron X-ray Diffraction Rleasurements 

I X17B11 

G. Chen, Y. Sinelnikov. AI. T. Vaughan, and R. C. Liebermann (SUNYat Stony 

Brook,) 

Adpatation of the ultrasonic interferometric techniques to be used in a cubic 

anvil high pressure apparatus installed at the National Synchrotron Light Source 

(X17B1) of the Brookhaven National Laboratory allows simultaneous ultrasonic and 

synchrotron X-ray diffraction measurements at high prcssure antl high temperarure 

in polycrystalline specimens. Cold-pressed and polished NaCl pellets (with grain 

size on the ortler of microns) capable of transmitting high frequency (to 60 hIHz) 

acoustic waves on the bench were used as the speci~nens. Experimental runs have 

been attempted to 8 GPa and 700 K with the pressure determined bv the X-ray 

diffraction volume change of the specimen ancl temperature monitored actively with 

a IV-Re ther~noco~iplc. This new development cxterids the measurement capability 

of ultrasonic equation of state experiments on NaCl at simultaneous elevated pressure 

and temperature by a factor of 10 in pressure and at comparable temperature, 

which is limited at present by the recrystallization of NaCl at higher tcmpcrature. 

Further cle\~elopment iri sample handling, c.g.. keeping the sample in extremely dry 

contlition, ma,v allow us to reach cvcn higher temperature at high pressure. such 

as those reached iri the AIgO experiment (1500 K) reported in a scpnratc NSLS 

abstract. These new velocity data will allow the tleterrnination of he cross prcssure 

and tempcrnturc tleper~tlence of the elasticity of NaC1. and with the vohrrrie data 

form the basis for refining the pressurc scale for this important stantlartl ~naterial. 

I An Ex~erimental Design for Low Pressure and Hiwh Temperature I X17B1 1 

J. Chen (CHiPR? SUNY at Stony Brook) 

While people are striving for higher and higher pressure to study the physical 

properties of materials under high pressure, there still are many demands for in 

situ x-ray diffraction experiments at low pressure (< 1 GPa) and high temperature, 

for example, phase relation of enstatite ancl zeolite. Some materials may have a 

restricted phase stability field below 1 GPa. However, the existing high pressure 

diffraction designs of a DIA-type press are generally suitable for high temperature 

experiments at the pressures above 1 GPa. For carrying out a high temperature 

experiment below 1 GPa, the major problems with a regular 6 mm high pressure cell 

(Figure 1) is a) unstable electrical contact between anvil and heating component: 

b) unfavorable pressurc control because of the very low required load. 

To perform such a low pressure antl high temperature experiment. a large anvil 

truncation high pressurc cell was designed (Figure 2). Six steel anvils with the truncation 

size of 15 mm were used. The size of pressnre medium was 20 x 20 x 20 111n1. 

The pressure efficiency was reduced by 1 order so that a good contact was achieved 

by rnuch higher load at the sample pressnre as low as 0.3 GPa. A thernlocorlple 

was inserted from one end of the heater to avoid the partial overheating due to 

the therrnocouplc hole on the heater sleeve (Figure 1). Au experinlent was carried 

out to st~rtly the phase boundary between orthocnstatite and protoenstatitc. The 

sample was heated up to 1600 "C at 0.3 GPa. Some diffraction patterns which (lo 

not haw the characteristics of either phase were obscrvccl at the temperature above 

1000°C. Frlrthcr irrvestigatiorl is in progress. 

Figure 1. Regular 6 mm high pres- 

sure cell assembly for the DIX-type press Figure 2. Large volume pressure cell for 

SXS18.5. studies below 1 GPa.

CC) 

I Following Olivine-Spinel Phase Transition in Fayalite with TIPS I X17B1 I 

J. Chen and D.J. Weidner (CHiPR, SUNY, Stony Brook) 

The mechanism of the olivine-spinel phase transition has been investigated by 

several groups. Sung and Burns [1,2] proposed a diffusion-controlled process, incoherent 

nucleation of the spinel phase and subsequent crystal growth; Kronberg 

[3] and Poirier [4] proposed a shear mechanism, stacking faults in oxygen lattice 

of olivine in company with cation reordering. More interesting result reported by 

Furnish and Bassett [5] from their in situ x-ray diffractions in a diamond anvil cell 

(DAC) suggested a two-step shear mechanism with stacking faults prior to the cation 

reordering. Using the newly developed translating imaging plate system(T1PS) for 

high pressure diffraction at X17B1, we studied the mechanism of the olivine-spinel 

phase transition in fayalite. 

The experiment was carried out by compressing the sample at room temperature 

into the spinel stability field (6.9 GPa) and then heating the sample. The sample 

transformed from olivine to spinel during the heating. A time-resolved pattern was 

recorded when the temperature increased from 300' C to 400°C. The transporting 

speed of the imaging plate was 3.25mm/min. The heating rate was 1.75 ' ~/min. 

Figure 2 shows the time resolved diffraction pattern. Structure refinements were 

done base on the diffraction patterns during the phase transition. Figure 2 shows 

an example of the refinement. The result shows that the oxygen framework of 

spinel structure is formed prior to the ordering of cations into the tetrahedral and 

octahedral sites. 

/ I 

1 J. P. Poirier, J. Geophys. Res. 87, 6791(1982). 

2 C. M. Sung and R. G. Burns, Earth Planet. Sci. Lett. 32, 165(1976). 

3 M. L. Kronberg, Acta Metall. 5, 507(1957). 

4 J. P. Poirier, in Anelasticity in the Earth, Geodyn. Ser. vol. 4, edited by F. 

D.'stacey et al. p: 113-117, AGU, Washington D.C. ("1981). 

[5] M. D. Furnish and W. A. Bassett, J. Geophys. Res. 88, 10333(1983). 

, , , , , ,,, , , ,, , , 

- -d-.&-4-M4.-., --,-,-- 

. . 

" c i . l i I I 1 

0' C L 3 6 '0 2 L 3 6 1 8 2 3 2 2 2 4 

2-11111:. eea XIOF I 

Figure 1. 3-D plot of time resolved Figure 2. Reitveld refinement of the 

diffraction patterns for the olivine-spinel diffraction pattern at midway of the 

phase transition in fayalite. olivine-spinel phase transition. 

Stress Measurement of Anhydrous and Hydrous phase of Ringwood- 

1 ite I X17B1/ 

J. Chen, D. J. Weidner, T. Inoue, H. Kagi and M. T. Vaughan (CHiPR, SUNY, 

Stony Brook) 

As one of the studies of the rheological properties of mantle minerals, we carried 

out a stress measurement for anhydrous and hydrous phases of ringwoodite in the 

T-cup press. In our previous study, we measured the stress of dry and hydrous 

phase of olivine, wadsleyite as a function of pressure, temperature and time [I]. We 

observed a difference in water weakening on the rheological property of olivine and 

wadsleyite. Olivine is weakened dramatically by introducing a small amount (1500 

ppm in weight) water. However, hydrous wadsleyite is just slightly weaker than 

its anhydrous counterpart although the hydrous phase takes as much as 2.2 wt% 

water. 

The samples were synthesized at 19 GPa and 1300°C using the USSA2000 press 

at Stony Brook. The water content of the hydrous phase was measured to be 3.8 

wt% by secondary ion mass spectrometory (SIMS). The result is shown in Figure 

1. No data were collected for the anhydrous phase at 400°C because no stress 

drop is expected based on the previous run for the hydrous phase. The behavior 

of the ringwoodite is similar to that of the wadsleyite at temperatures up to 400°C 

although there are somewhat greater experimental errors. Up to 600°C the yield 

strength drops by 29% and 39% in the anhydrous and hydrous phases respectively, 

and further drops of the yield strength are observed with further increase of tem- 

perature: 29% and 38% from 600°C to 800°C, and 20% and 48% from 800°C to 

1000°C in the anhydrous and hydrous phase respectively. Both phases show stress 

relaxation as a function of time at each temperature. The strength of the hydrous 

phase at 1000°C is close to zero and the limited instrumental resolution results in 

larger scatter, and some data are scattered below the base level. 

[l] J. Chen, T. Inoue, Y. Wu, D. J. Weidner and M. T. Vaughan, NSLS Report 

1996 B-139. 

Load (GPa) 

0 10 20 +constant P at -20 GP+ 

0 1 0 1 2 3 0 1 0 1 2 

Time (x103 s) 

Figure 1. Stress in the anhydrous and hydrous phase of ringwoodite.

I Rheological Study of Loner Mantle Minerals. Perovskite and Peri- 

4! clase l x17~ll 

d I 

J. Chen, D. J. Weidner, hI. T. Vaughan and H. Kagi (SUNY at Stony Brook) 

The lower mantle is considered mainly consisting of (Fe,h,Ig)Si03 perovskite and 

h'lgO periclase. As one of the studies on rheological properties of mantle minerals[1,2], 

we carried out the stress measurement on perovskite and periclase in the 

T-cup press. In our previous study. we have found that the upper mantle mineral 

olivine is much weaker than the transition zone minerals, wadsleyite ancl ringwooclite, 

especially when water is present. Rheological properties of lower mantle minerals 

are important for constraining mantle convection ancl understanding the origin of 

deep focus earthquakes. 

The perovskite sample was synthesized at 26 GPa ancl 1800°C using the 

USSA2000 press at Stony Brook. The structure mas confirmed by x-ray diffraction 

before the experiment. The powdered sample was first compressed up to 20 

GPa at room temperature antl then was heated np to 1000°C stepwise. At each 

heating step the temperature was held for several tens of minutes during which 

diffraction data are recorded as a function of time. The results arc shown in Fig- 

11rc 1 antl Figure 2. The perovskite ant1 periclase have quite tliffcrent rheological 

properties. the perovskitr is very strong ard the pcriclase is very weak. 

i\lthough the perovskitc shows very strong rheological behavior. the lower mantle 

may still have weak characteristics since hIgO is much weaker, being comparable 

to olivine. Results of the rhcological study on the mantle n~irlerals, olivine, wads- 

Icyitr, ringwootlite, perovskite and 1IgO 111ay constrain the origin of thr tlrep focus 

earthquakes in tcrrns of storage of stress. 

[I] -1. Chen, T. Ir~ouc. Y. \GI, D. .T. \\'citlner and hI. T. Vaughan. NSLS Report) 

l99G B-139. 

121 -1. Chcn. D. J. ~\.Teitlncr. T. Inoue. H. Kagi and hI. T. Vaughan. in this Report 

Load (GPa) 

0 10 21 - corslarl pressure at -20 GDa - 

Figure 1. Stress in the perol-skite. Figure 2. Stress in the periclase. 

Time Resolved Diffraction Measurement with an Imaging Plate at 

High Pressure and Temperature 

X17B1 

J. Chen. D. J. Weidner: RI. T. Vaughan. R. Li, J. B. Parise, C. C. Kolecla and K. 

J. Baldwin (CHiPR, SUNY at Stony Brook) 

An imaging plate (IP) has great potential to acquire high quality in situ x- 

ray diffraction data at high pressure and temperature in both a diamond anvil cell 

(DAC) [I-21 and large volume apparatus [3-41. The off-line developing of an imaging 

plate is a clisaclvantage for quick data collections. Effortls have been made to install 

an on-lone imaging plate scanner for reducing the operation time. Time resolntion 

in the sequence of consecutive exposures is on the order of tens of minutes. Recently 

rapid development of a CCD (charge coupled device) provides a good opportunity 

to perfornl time resolved data collectior~. Nevertheless. the current commercial 

CCD has very limited active detecting area (-50 x 50 m1n2) which results in a 

relative low resolution when the CCD is used to record a large-range tl-spacing 

pattern. IVe have tlevelopecl a translating imaging plate system (TIPS) with the 

large-volume multi-anvil ~tpparatt~s SAh185 at t,lw heamlinc X17B1 to acquire tinie 

A A 

rcsglvecl diffraction. 

\Ye introtl~lcetl a lead screen with a vertical slit in the middle in the front of 

~ ~~~~~ ~ 

the imaging plate to define the tiinlension of exposure on the detector (Figure 1). 

The imaging plate holtler is nlountctl on a horizontally rrwtor-control stage, antl the 

translation guide block is pcrpcntlic~~lar to the iricitlent x-ray bearn. A 200 rnrrl x 

400 mn imaging plate is nsed for the data collection. Width of the slit is acljustetl 

depending on the beam intensity, IP-tc-sample distance and the t,ransportirrg speed 

of thr imaging pke. A tlircct heam stop is monntetl ou the slit. The heam st>op 

blocks most ol the intensity of the tlircct beam. antl allows t,hc tlircct bram to expose 

thc imaging plate with thc same intrnsity as a tliffractetl hcan~ (as shown 011 the top 

of Fig~~rc 2). Olivine-spinel pliasc t,ritnsition in fvalite was ir~vrstigatcd with this 

systeln. Fignre 2 shows a time resolved diffraction pattern rccortlctl on thc imaging 

platc (luring thr phase transition. The data rnable 11s to stutlp thc sample strrsses 

during the phase transition and the pt~asc transition rnectiariisru. 

[I] 0. Shimomllra, K. Takemura. El. F~Gihisa. Y. Fujii. Y. Ohishi. T. Kik~gawa. 

Y. Arncrniva, T. XIatsushita. Rev. Sci. 1nstr11111. G:

Sound Wave Velocity Measurements at High Pressure and Temper- 

ature for Polycrystalline MgSiOs Orthopyroxene 

X17B1 

L. Flesch, B. Li, J. Zhang, J. Cooke, R. Liebermann, and M. Vaughan, (CHiPR, 


Polycrystalline samples of MgSi03-orthopyroxene were hot pressed at pressures 

of 4 GPa and temperatures of 1250 K in a uniaxial split-cylinder apparatus (USCA- 

1000). The recovered specimens have a bulk density within 1% of the x-ray density, 

and compressional and shear wave velocities within 1% of the Hashin-Shtrikman 

averages of the isotropic velocities calculated from the single crystal elastic moduli. 

Preliminary acoustic velocity studies were performed on these samples; we have 

successfully measured P-wave travel times as functions of pressure to 6.5 GPa and 

temperature to 1300 K in a DIA-type, cubic anvil apparatus (SAM 85) installed on 

the superconducting wiggler beamline (X17B) at the National Synchrotron Light 

Source of the Brookhaven National Laboratory. 

Comparison of Experimental Electron Spectra with the Integrated 

TIGER Series (ITS) Simulation 

X17B1 

N. A. Guardala, D. J. Land, J. L. Price (Naval Surface Warfare Center), Y. Wang, 

and G. A. Glass (U. Southwestern Louisana) 

Measurements have been made on beamline X17B1 of the emitted electron spec- 

tra for 58 keV photons incident on a 680 A titanium target and a 400 A carbon 

target. The goal of this work is to examine the prominent features of the electron 

spectra, such as the Compton-recoil, Auger, and photo-electrons, and to determine 

how well they are described by current transport models. The measurements were 

performed at zero degrees with respect to the incoming photon beam. The elec- 

trons were energy analyzed using a semihemispherical, double focussing electrostatic 

analyzer coupled to a channeltron electron multiplier for electron detection. 

The results for the Ti data are shown in Fig. 1. The peaks representing the 

Compton-recoil electrons at 10 keV and the Auger electrons at 4 keV stand out 

clearly. Also shown are the results of a simulation of 58 keV photons incident on 

680 A Ti performed with the TIGER code, one of the Integrated TIGER Series 

(ITS) electron/photon transport codes, Ver 3.0 [I]. This curve has been normalized 

to the area under the experimental Compton peak from 4.5 to 14.0 keV. Overall, the 

agreement is satisfactory: the ratio of the experimental Compton to Auger yields 

is 0.91 while the same ratio for the simulated yields is 0.81. However, there are 

some obvious differences, the most notable of which is the fact the the simulated 

spectrum does not take account of the broadening of the electron spectrum caused 

by the internal motion of the electrons, the Compton profile. 

[l] J. A. Halbleib, R. P. Kensek, T. A. Mehlhorn, G. D. Valdez, S. M. Seltzer, 

and M. J. Berger, ITS Version 3.0: The Integrated TIGER Series of Coupled Elec- 

tron/Photon Monte Carlo Transport Codes, Sandia National Lab. Report No. 

SAND91-1634, UC-405. 

58 keV PHOTONS on 680 A Ti 

I MOO i I 

I 

0 2 4 6 8101214 

ELECTRON ENERGY (keV) 

Figure 1. Acoustic signals from an S-wave run on a polycrystalline MgSiOs speciman 

at -6 GPa and 700 C. The first echo represents a reflection off the anvil (Al), the Figure 1. Comparison of the measured electron yield (diamonds) with results from 

second a reflection off the buffer rod (Bl), and third a reflection from the end of the TIGER code (solid curve) as a function of electron energy for 58 keV photons 

the sample (S1). incident on 682 A Ti.

Elasticity of Polycrystalline R/1g4Si4012 Majorite Garnet at P=9 

Gpa and T=1000K in a DIA-Type Cubic-Anvil Apparatus Inter- 

facecl with Synchrotron X-rays 

X17B1 

G. Gwanmesia (DSU). G. Chen. J. Cooke: L. Flesch: R. Liebermann. and AI. T. 

Vaughan (SUNY at Stony Brook) 

Dense isotropic polycrystalline h'Ig4Si4012 majorite garnet were fabricated at 

high pressnres and temperatures in a 2000-ton uni~~ial split sphere anvil apparatus 

(USSA-2000) using hot-pressing techniques developed previously by Gmanmesia and 

Liebermann (1992; see also Gwanmesia et al., 1993). These specimens have bnlk 

densities identical to the x-ray density antl exhibit compressional (P) wave and 

shear (S) wave velocities within 0.2% of single crystal elastic moduli of Pacallo and 

LVeiclner (1997). Recent technological development in our laboratory has enabled 

precise interferometric measurements wave velocities in minerals to be performed to 

pressures of 9 Gpa and temperatures of 1500K in a DIA-type, cubic anvil apparatus 

(SAlI-85) interfaced with white x-ray radiation from the superconducting wiggler 

port of the National Synchrotron Light Sonrce at Brookhaven National Laboratory 

(see Liebermann ct al., 1997). have obtained new data on the pressure antl 

temperature tlepentlence of S wave velocity in the llg.~Si.tO~~ majorite to 7 Gpa 

at 1000K. The new tlata are combined with previous data for P wave and cornpared 

with acoustic antl PVT tlata for other compositions in the Pyrope-ruajorite 

solid solution series, especially those for a Py~2h1j:js specimen studies by Rigtlen. 

Gwanrnesia arid Liebermann (1994) antl IVang et al. (lW3). 

The Crystal Structure of Bi4Au2014: The Use of a Siemens CCD 

Detector with Short-Wavelength Radiation 

X17B1 

R. Harlow (DuPont), J. Parise (SUNY at Stony Brook), J. Phillips and C. Campana 

(Siemens). and J. Hanson (BNL) 

The determination of the structure of Bi4Au2014 presented two difficulties: ab- 

sorption (mu for hIoKa is approximately 1050 cm-1) and the presence of a superlat- 

tice which is 4x the sublattice. Three sets of data have been collected on crystals of 

this compound: with in-house hIoKa radiation using a Siemens CCD ancl a Rigaku 

image-plate system, ancl with 0.185 A synchrotron radiation (where mu is reduced 

to approximately 30 cm-1) at beamline X17B1, also with a Siemens CCD. At this 

point, the snbcell structure (tetragonal. a = 8.676 ancl c = 5.832 A, in space group 

P4212) has been solved and refined using the synchrotron data to an R value of 

10.3% using 2094 reflections to a resolution of ca. 0.3 A. All of the atorns were 

refined with anisotropic thermal parameters, with special attention given to those 

of the oxygen atoms which are the pres~lmable source of the snperlattice. One of 

the oxygen atoms was found to be disordered over two sites: it is believed that this 

oxygen mill be ordered in the supercell where the c-axis is doublrd. This type of 

disorder mas expected because the Bi site in the snbcell contains a mixtnre of Bi+'' 

antl ~i'". Presumably, the latter arc also ordered in the supercell. The source 

for tloubling the cell along the a-b diagonal has not yet been tlctrrminetl. Using 

the in-ho~ise data, only the heavy atorns codtl be refined with anisotropic thermal 

parameters antl some of these ellipsoids were not very realistic. Also, the tlisortler 

of the one oxygen atom was not visitk from the in-house tlata. Ikrk continues on 

rnotlelling thr superccll strnctnre, hut thc bcncfits of using the (alrnost) absorption- 

free tlata from the synchrotron/CCD combination are already clc:rrly evident.

Strength Measurements of Carbonado, A Natural Polycrystal Dia- 

mond. 

H. Kagi, J. Sweeney, J. Chen and D.J. Weidner (SUNY at Stony Brook) 

X17B1 

Carbonado is a natural polycrystal diamond, and its texture can be similar to that 

of an artificial sintered diamond. Carbonado is expected to be one of the strongest 

material in terms of hardness, because each micro crystal constituting carbonado 

polycrystal is arranged without orientation and there exists direct covalent bonding 

of diamond between micro crystals. In the grain boundaries, it is known that some 

other minerals are contained as impurities. To obtain information on the strength 

of carbonado, we observed stress-induced line broadening of X-ray diffraction lines 

of carbonado diamond at high pressure and high temperature. The cell assembly 

we used is a typical high pressure cell for a DIA-type, cubic anvil, high pressure 

apparatus on X-17B1. Carbonado was loaded into a boron nitride capsule after 

grinding to powder. This was because a chunk sample (carbonado as it is) without 

powdering cannot be expected to reveal line broadening induced by grain contacts. 

NaCl powder was also loaded in the cell assembly for a pressure calibration, and 

a thermocouple was located in the center of the sample. Pressure was increased 

to around 10 GPa at room temperature, and (111) diffraction peak of diamond 

(carbonado) broadened and peak position shifted toward the lower d-spacing. At 

the highest pressure, temperature of the cell was increased to around 1500 degree 

C and change in the line shape was observed. We are going to compare the results 

from two different types of carbonado, and the difference from the artificial diamond 

powder will be considered. 

Direct Determination of Pressure-Temperature Paths in the Laser- 

Heated Diamond Anvil Cell 

X17B1 

A. Kavner and T. Duffy (Princeton U.), G. Shen (CARS), D. Heinz (U. Chicago), 

and R. Jeanloz (U.C at Berkeley) 

The determination of accurate pressure-temperature equations of state require 

reliable in-situ standards. To establish a high-pressure high-temperature diamond 

anvil cell standard, and to investigate the conditions inside the sample chamber at 

extreme P-T conditions, the behavior of platinum was examined at high pressures 

and temperatures in the double-sided laser-heated diamond anvil cell. The lattice 

parameter of platinum normal to the diamond-loading axis was monitored as a 

function of temperature, and was compared with the pressure-temperature equation 

of state determined from the shock Hugoniot. 

Traditionally, pressure cannot be measured during laser heating, so the pressure 

at high temperatures is taken to be either the pressure measured before heating, 

the pressure measured directly afterwards, or a combination of the two. Extensive 

pressure changes within the sample chamber occur at high temperatures, as recorded 

by the lattice parameter of platinum, that are not apparent from looking at the 

difference in the room temperature measurements taken before and after heating 

(Fig 1). These pressure drops are too large to be accounted for by a thermal 

pressure or thermal expansion effect, and possibly occur as a result of gasket and 

cell relaxation at elevated temperatures. The relaxation effect was still present, yet 

less pronounced during a second heating cycle of the same sample. The experiments 

were repeated using alumina and NaCl as insulating layers, with alumina showing 

an enhanced relaxation effect. 

m 

Platinum in A1203 


Figure 1. Pressure-Temperature path of platinum in the laser-heated diamond anvil 

cell. cycles are shown. Contours are of constant V/Vo.

CI 

w 

le 

High Pressure High Temperature Behavior of an Iron-Nickel Mete- 

X17B1 

orite 

A. Kavner and T. Duffy (Princeton U.), G. Shen (CARS), and R. Jeanloz (U.C at 

Berkeley) 

Terrestrial planetary interiors are presumed to be composed of an iron nickel alloy 

with a range of lighter mass impurities. The behavior of planetary cores helps govern 

the planetary dynamics. including differentiation, magnetic field effects, ancl the 

heat transfer that controls convective properties. Experimental insight into the behavior 

of core-type alloys is of great interest to dynamicists and mineral physicests. 

Iron-rich metallic meteorites are thought to be remnants of the differentiated core of 

a proto-planet; perhaps similar to bodies that coalesced to form t,he Earth antl other 

terrestrial planets. The high-pressure high-temperature behavior of an iron-nickel 

rneteorite was exanlined using the laser-heated diamond anvil cell in combnation 

with in-situ x-ray diffraction. 

At room pressnre and temperature, the iron nickel rneteorite is in the bcc structure, 

antl transfornls to hcp ~tnder pressures above 5 GPa. The hcp sample is heated 

to about 1000 K at 20 GPa, mtl irnrnetliatel?; transforms to an fcc structured material. 

\Vith further heating (1000-2500 K) the sample rernairled in its fcc structure, 

however there were significant changes in the line intensities, indicating solid-state 

recrystallization antl textttring. Upon quenching to room temperature, the hcp 

structure is recovered, howcvcr there is sortie resitlual fcc structure. Heating antl 

diffraction was done with the sarnplc at 20 antl at 40 GPa. 

Simultaneous Ultrasonic Interferometry and in-situ X-ray Studies 

on Wadsleyite (0-h11g2Si04): P-V-Vp-Vs-T Measurements to 7 GPa X17B1 

885K 

B. Li, J. Liu, L. Flesch, R. C. Liebermann, J. Chen (SUNY at Stony Brook). and 

G. D. Gwanmesia (Delaware State U.) 

We have conducted acoustic wave velocities measurements and equation of state 

(P-V-T) studies on waclsleyite (8- hlgnSiOLi) using simultaneous ultrasonic interfrometry 

and in-situ X-ray diffraction techniques in a DIA-type. cubic anvil high 

pressnre apparatus (SAhI85) installed at beamline X17B of the National Synchrotron 

Light Source at the Brookhaven National Laboratory. The polycrystalline 

specimen (K270) mas hot-pressed at 15GPa ancl 1500 K in a 1000-ton Uniaxial 

Split Cylinder Apparatus (USCA-1000). The sample was identified as single phase 

of wadslcyite by X-ray diffraction with a bulk density of 3.470 g/cm3 (0.2% porosity). 

Compressional and shear wave velocities at ambient P arltl T agree with 

single crystal data (Sawanloto et al., 1984) within 0.5%. High P antl T ultrasonic 

measurements iri the SAXI-85 apparatus are implemcntcd by mounting an acoustic 

transducer at the back of the 11 C anvil and enclosing glass as extended buffer rod 

inside the cubic Boron epoxy pressm-e rnedilt~n (see figure below). The sample is 

st~rrountletl by NaCl and BN to minimize non-hytlrostatic stress. X-ray diffraction 

spectra, frorn both the sample and NaCl were recortletl at elevated pressures and 

temperatures frorn which the unit cell volumes of the sample and cell pressures 

were retrieved. The temperatures were measured using thermocouples adjacent 

to the sample. The experimental P-T path has been designed to minimize nonhytlrostaticity 

anti to optirnizc acoustic signals. Cornpletetl P-1'-T antl \'p antl 1's 

tlata for the specimen K270 have been collcctetl up to 7 GPa and 885 I< with tlerise 

coverage in P-T space by performing a few corr~pressiori/lieati~lg and deconlprcssiori/coolirig 

cycles below thesr contlitions. Corlthining P-V-T antl acoustic data 

will provide the absolute pressure scale antl precise tletermination of elastic moduli 

K and G antl their pressure ancl temperature. These tlata are very important 

parameters needed for modelling mantle cornpositions and interpreting the 410 krn 

tliscontinl~ity in the Earth's transition zone. 

P-V-VpVs-T in DIA-type Apparatus (SAMSS) 

Figure 1.

Simultaneous Ultrasonic Interferometry and in-situ X-ray Studies 

on Forsterite (MgzSi04-olivine): P-V-Vp-Vs-T Measurements to 8 

GPa and 1300 K 

B. Li, J. Liu, L. Flesch, , R. C. Liebermann, J. Chen (CHiPR, SUNY, Stony 

Brook), Brian Savage (UC Berkeley) 

We have conducted acoustic wave velocities measurements and equation of state 

(P-V-T) studies on forsterite (MgzSi04-olivine) using simultaneous ultrasonic in- 

terfrometry and in-situ X-ray diffraction techniques in a DIA-type, cubic anvil 

high pressure apparatus (SAM85) installed at beamline X17B of the National Syn- 

chrotron Light Source at the Brookhaven National Laboratory. The polycrystalline 

specimen (G717) was hot-pressed at 6 GPa and 1400 K in a girdle- anvil, high- 

pressure apparatus. The sample was identified as single phase of forsterite by X-ray 

diffraction with a bulk density of 3.20 g/cm3 (0.3% porosity). Compressional and 

shear wave velocities at ambient P and T agree with single crystal data (Kumazawa 

and Anderson, 1969) within 1%. High P and T ultrasonic measurements in the 

SAM-85 apparatus are implemented by mounting an acoustic transducer at the 

back of the WC anvil and enclosing alumina as extended buffer rod inside the cu- 

bic boron epoxy pressure medium. The sample is surrounded by NaCl and BN to 

minimize non-hydrostatic stress. X-ray diffraction spectra from both the sample 

and NaCl were recorded at elevated pressures and temperatures from which the 

unit cell volumes of the sample and cell pressures were retrieved. The temperatures 

were measured using thermocouples adjacent to the sample. The experimental P-T 

path has been designed to minimize non-hydrostaticity and to optimize acoustic 

signals. Complete P-V-T and Vp and Vs data for the specimen G717 have been 

collected up to 8 GPa and 1300 K with dense coverage in P-T space by performing 

a few compression/heating and decompression/cooling cycles below these condi- 

tions. Combining P-V-T and acoustic data will provide the absolute pressure scale 

and precise determination of elastic moduli K and G and their pressure and tem- 

perature. These data are very important parameters needed for modelling mantle 

compositions and interpreting the 410 km discontinuity in the Earth's transition 

zone. 

I Thermal Equation of State of Stishovite I X17Bll 

J. Liu, J. Zhang, L. Flesch, B. Li, D. J. Weidner, and R. C. Liebermann (SUNY 


The pressure -volume-temperature (P-V-T) behavior in SiOz-stishovite has been 

studied using a DIA-type, cubic-anvil apparatus (SAM 85) and in situ synchrotron 

X-ray diffraction at the superconducting wiggler beamline (X-17B) of the National 

Synchrotron Light Source at Brookhaven Nationaal Laboratory. Polycrystalline 

specimens previously hot-pressed in a uniaxial split-sphere apparatus were used 

to minimize the deviatoric stress which could affect the accuracy of cell parameter 

determination. The P-V-T data to pressures of 10 GPa and temperatures of 1300 K 

were analyzed using several approaches, including a temperature-dependent Birch- 

Murnaghan equation-of-state, isothermal compression, and isobaric expansion. The 

results obtained from these different approaches show that the entire data set is 

internally consistent. The bulk modulus (KO) and axial compressibility of stishovite 

are compared with values obtained from Brillouin scattering and diamond-anvil cell 

X-ray studies on single crystal stishovite and ultrasonic studies on polycrystalline 

specimens. The temperature derivative of bulk modulus at zero pressure (dK/dT) 

was measured for the first time to be -0.036(11) GPa/K.

Formation of a-eucryptite, LiA1Si04: An In-situ Synchrotron X- 

ray Powder Diffraction Study of a High Temperature Hydrothermal 

Synthesis * 

X17B1 

P. Norbv (SUNY at Stonv Brook), J. C. Hanson, L. Flaks. J. Hastinns (BNL) 

Hydrothermal conversion of zeolites is an alternate route for preparation of zeolites 

ancl other aluminosilicate materials. Hydrothermal conversion of zeolite Li- 

A(BMT). LiAISiO't H20, into a-eucryptite, LiAlSi04, occur at temperatures above 

350 C. This is the first in-situ study of a high temperature hydrothermal synthesis 

using time resolved powder diffraction. Hydrothermal reactions were performed 

in stainless steel capillaries with a diameter of 1.6 mm. In order to maintain hydrothermal 

conditions. a hydraulic pressure of 2-300 atm was applied. 35-40 keV 

synchrotron X-ray radiation was used in order to penetrate the steel capillaries. 

Angle dispersive time resolved powder diffraction patterns were collected using a 

Translating Imaging Plate (TIP) camera. Anhydrous Li-ABW, LiA1SiO.l was used 

as the starting material, antl the rehytlration into zeolite Li-A(B\V) as well as the 

subsequent conversion into a-eucrvptite mere observed. Using integrated intensities 

of a number of diffraction peaks, transformation and crystallization curves 

were obtainrcl. Figme 1 shows a 3-clirnensional representation of a small part of the 

diffraction pattern as a fur~ction of tirne, and the transforrnations are clearly visible. 

An intermediate phase was observed in some of the experirnents, antl was identified 

as another polyn~orph of LiAlSiOl, N- eucryptite. Fignre 2 shows an example of 

transfor~nation antl crystallization curves extracted from the patterns. 

- 

0 20 40 60 80 1W 120 140 160 

Fignre 1. xrne (mln ) 

^ DOE BES DE,\C02-76CH00016 

Figure 2. 

I Shear Wave Velocitv of MgSiOa Perovskite up to 8 GPa and 400°C I X17B1 I 

Y.D. Sinelnikov, G. Chen, J. Liu, D. Neuville, R. C. Liebermann, and D.J. Weidner 


High quality polycrystalline specimens of the nIgSiO3 perovskite have been synthesized 

in a 2000-ton multianvil split-sphere apparatus (USSA-2000) at 26 GPa 

and 1350°C using glass as the starting material. The perovskite structure has been 

confirmed by Raman spectroscopy and X-ray diffraction analyses from the ends of 

the cylindrical specimens. After polishing the specimens under liquid nitrogen (to 

protect them from morphization) we performed pilot acoustic experiment at room 

temperature to the pressures up to 5 GPa in a 1000-ton uniaxial split-cylinder ap 

paratus (USCA-1000) press. The acoustic quality of perovskite specimen was to 

be excellent at elevated pressure, but the acoustic echoes were barely observable at 

room pressure. most likely due to the large grain size of synthesized material (up 

to 50 microns). Two subsequent experiments have been performed in a DIA-type, 

cubic anvil apparatus (SAM 85) installed on the superconducting wiggler beamline 

(X17B) at the National Synchrotron Light Source of the Brookhaven National 

Laboratory. The coustic measurements were performed simultaneonsly with in-situ 

X-ray diffraction monitoring of the perovskite sample ancl NaCl stantlard, which 

was used to determine the pressure. (Lieberrnann et al., 1997, AIRAPT). The ternperatwe 

was measured by two thcr~nocouples and the gradient determined to be 

less than 10C/mrn. As a result of these experirnents, the shear elastic rnotlulus of 

ht~SiO? ~erovskite has been measured as a function of temnerature and nressure 

c, -. 

for the first time.

Thermoelastic Properties of CaTiO3-CaSiO3 Perovskites I X17B1 

Y. Sinelnikov, J. Zhang, R. C. Liebermann (CHiPR, SUNY at Stony Brook) 

Polycrystalline specimens of end-member CaTiO3 and intermediate CaTi0.m 

Sio.zs03 and CaTio,5Sio.503 perovskites were hot- pressed in a 2000-ton uniaxial 

split-sphere apparatus (USSA-2000). Intermediate compositons were synthesized 

at pressures of 15 GPa and temperatures above 1800 K. The pressure -volumetemperature 

(P-V-T) behavior in these specimens has been studied using a DIAtype, 

cubic-anvil apparatus (SAM85) and in situ synchrotron X-ray diffraction at 

the superconducting wiggler beamline (X-17B) of the National Synchrotron Light 

Source at Brookhaven National Laboratory. The P-V-T data to pressures of 8 

GPa and temperatures of 1100 K were analyzed using a temperature-dependent 

Birch-Murnaghan equation-of-state to obtain the isothermal incompressibility/bulk 

modulus and its pressure and temperature derivatives. 

Powder X-ray Diffraction for Anisotropic Compression Measure- 

ments at High Pressures / X17Bll 

M. S. Somayazulu, Y. Z. Ma, J. Z. Hu, J. F. Shu, H.-K. Mao, R. J. Hemley (Carnegie 

Inst. Washington, CHiPr), M. Rivers (U. of Chicago), T. Duffy (Princeton U.) 

Determining the effect of pressure on the elastic properties of materials is essential 

for understanding mecahnical stability of solids, material strength, seismology and 

phase transformation mechanisms. We report the setting up of an experimental 

technique which is capable of measuring the elastic properties of materials at Mbar 

pressures and temperatures of the order of 2000 K from powder samples. 

Elastic constants of the polycrystalline specimen are obtained from evaluating the 

variation of the d-spacing as a function of q, the angle between the idirection and 

the stress axis of the sample in the diamond anvil cell [I]. Radial x-ray diffraction 

technique at ultr-high pressures using a high strength Be gasket makes such a measurement 

possible. However, the diffraction data has to be collected from extremely 

small sample volumes (typically 5-10 p3) enclosed in a relatively thick Be smaple 

chamber. This requires the use of a high brilliance, white x-ray source available 

at the wiggler beamlines. To enable data collection from a stationary smaple, an 

array of detectors are used wherein each detector images a small range of 9 values 

so that all the data can be collected at the same time. The diffraction angle and 

the diffracting volume are fixed by a specially designed conical slit assembly. The 

advantage of such a technique also being that laser heating of the sample becomes 

possible to allow studying elastic properties of materials at extreme P. T conditions 

for which we have installed a double sided laser heating set up using a Nd:YAG 

laser. Representative data collected from our studies on a geologically important 

material, FeO are shown below. 

1 A. K. Singh, - H-k Mao, J. F. Shu and R. J. Hemley (1997) Phys. Rev. Lett. 

(in I;ress) 

d rpac~ng (A) 

Figure 1.

+ 

c3 

A High-Energy Diffraction Study of the Bulk Critical Scattering in 

a V2H Crystal * 

J.Trenkler, H. Abe, P. Chow: D. Scarfe, S. C. hloss (U. of Houston), P. Wochner, 

Z. Zhong, J. Hastings (BNL). R. Hempelmann (U. des Saarlandes) 

A sharp quasi-Bragg peak in the critical scattering on top of a broad Lorentzian 

shaped peak for a SrTiOs-crystal has been recently observed by x-ray scattering. 

Thereby, the coexistence of two components in the critical scattering suggests the 

existence of two length scales in the critical fluctuations. Although the origin of 

the sharp component is not clear, it is believed to be related to surface phenomena 

such as local clistortions around defects close to the surface. 

In a recent experiment done at X14A, we observed a similar effect in the line 

shape of the critical diffuse scattering in a longitudinal [0 1 11 scan at T=Tc+Ci.2 

K in a V2H crystal. As shown in fig. 1, the measured profile clearly consists of 

a sharp and a broatl con~por~ent at a temperature of T=Tc+6.2 K measured in 

reflection geometry with a x-ray energy of 11.95 keV. In order to probe whether 

the two conlponents in the line shape are related to the two-length scale issue or 

not, we performed a high energy diffraction experiment in transrnissiorl geometry at 

the high energy bearnline X17B1 using 44.1 keV photons. A Si-111 aualyzrr crystal 

with a Ge-solid state detector was used to increase the q-resolution ar~l sllpprcss the 

X/2-contribution. In this espcrin~cnt, we nleasuretl the "true" bulk hhnvior and 

not just the behavior of the first 50 pm below the surface, since the entire crystal 

volume is probed by the ir~citler~t bear11 ovrr the illwninated region. Figl~rc 2 shows 

n scan rneasuretl at T=Tc.+6.5 K using a x-ray encrgy of 44.1 keV. Olwiollsly no 

sharp component on top of the broatl one is obsrrvetl. The n~easuretl data can be 

wcll-fitted by a single Lorcntzian corresponding t,o t,he broatl corupor~ent. 

Figure 1. CDS for the (0 512 $12) su- 

perstructure reflection in a heating run 

in [0 1 11 at T=Tc+6.2 K with a x-ray 

ener,qv of E=11.95 ke\- at S14=\. 

This work is supported bv the XSF on 

X17B1 

Figure 2. -1s fig. 1 but at E=44.1 keIT 

measured at S17B1. 

Equations of State of hIgSiOs in the Sub-Perovskite Pressure Range 

I* I X17B11 

AI. T. Vaughan, E. K. Bell, and J. Z. Zhang (CHiPR, SUNY at Stony Brook) 

The study of the phase relations of (h,Ig.Fe)SiOs (1996 NSLS Activity Report, 

B145) is continuing with a measurement of the equation of state (EoS) of the mag- 

nesium end member of the hlg-Fe solid solution described above. 

The study was going to be the measurement of stress relaxation of the ilmenite 

phase at about 10 GPa. at various high temperatures. The ilmenite sample studied 

previously (ibicl), mas from a natural enstatite and had about 10 mole percent 

FeSiOs, as well as small amounts of Al. There were several problems, and a reliable 

EoS has not yet been determined from that data set. 

The current. LIg encl-member sample, was much less stable, and after a few 

minutes at 600°C it transformed to a high-pressure form of clinoenstatite. The unit 

cell volume of the HP-CEn as a function of pressure and temperature is currently 

being tleterrninetl. The instability of the ilrncnitc phase is understandable, because 

we are operating outside of its stability field, bnt it is not known why the end- 

member is so much less stable than the natural sample. 

Further work on the hIgSiOs end rncmbcr will require high temperature mea- 

surements within (or closer to) its stability field. i.e. > 18 GPa (see Figure l.) 

0 5 10 15 20 25 

Pressure, GPa 

Figure 1. Phase Relations in bIgSi0:l. Diamond-shaped symbols are the current 

tlata set. The two highest-pressure points were ilrnenite phase: during the collection 

of the third tlata set. the sample transformed to High-pressure clinoenstatite. It 

remaind in this phase for the rest of the run. The data from last year are the 

fainter symbols in the background. 

* IVork supported ty the XSF under a grant to the Center for High Pressure Research 

and by the DOE under contract number DE-=\C02-76CH00016 to the XSLS

W 

Use of Sintered Diamond Anvils in a 6-8 High-pressure Apparatus 

I * 1 X17B11 

M. T. Vaughan, D. J. Weidner, J. H. Chen, and C. C. Koleda (SUNY at Stony 

Brook) 

The pressure capability of the Tcup apparatus (NSLS Activity Report 1995, B- 

140; 1996, B-145) has been extended to 22.8 GPa by the use of sintered diamond 

for the 1 cm cubes used as a second stage (Figure I). The sintered diamonds were 

Advanced Diamond Compacts (ADCs). ADC is a natural diamond product hotpressed 

with a Sic binder at modest pressure ( ~ GPa). 2 We achieved a pressure 

equivalent to our best tapered anvil run, with a maximum pressure of 22.8 GPa 

with a load of 110 tons. The untapered ADC pressure-load curve is tangent to 

the equivalent untapered WC curve at pressures below 5 GPa, but with much 

less curvature above there. At 110 tons, there is a 6GPa increase. We expect 

tapered ADC anvils to exhibit similar pressure increases. If we taper the anvils, 

and extroplate along the best -2' tapered trajectory, we would expect the pressure 

to reach 30 GPa at 120 tons (Figure 2). 

Stony Brook T-cup Press 

Figure 1. Tcup apparatus, showing eight 

10 mm second stage cubic anvils inside 

three of six first stage anvils, two of 

which are cut away to allow x-ray pas- 

sage 

* This work was supported by the NSF 

under a grant to the Center for High Pressure 

Research and by the DOE under contract 

number DE-AC02-76CH00016 to the 

NSLS. 

Effect of Tapering and Gaskets 

7mm octahedra, 2mm truncations 

0 20 40 60 80 100 120 140 160 

Rum Load, Ton& 

Figure 2. Plot of cell pressure vs. ram 

load for various anvil and gasket con- 

figurations. Heavy line is for the ADC 

anvils, the rest are WC. 

I Phase Transition in Zeolite A at 2 Kbars and 800" C Using SAM-85 I X17B1 I 

Y. Wang (U. Chicago), J. Chen, F. Bejina, (CHiPR, SUNY at Stony Brook), M. 

C. Hash, L. Leibowitz, M. C. Petri, J. W. Richardson, Jr., ( ANL) 

We report some preliminary results in an in-situ study on zeolite A, using SAM- 

85. A large volume BN cell (20x20~20 mm) was used and two samples were packed 

in the cell: a pure zeolite A, and the other mixed with 5 wt percent glass; they were 

separated by a layer of NaC1, also used as the pressure standard. Strong diffraction 

signals were observed at 1 bar for both samples (Figs. 1A and 2A). At 2 kbar 

and room temperature, diffraction peaks became broad and weak (Figs. 1B and 

2B). In the glass-containing sample, close to the sample/NaCl interface (0.1 mm), 

additional peaks appeared (compare Fig. 2B with IB); 0.2 - 0.3 mm away from 

the interface, the spectrum ressembles that of an amorphous material (Fig. 2C). 

Upon increasing temperature, pure zeolite quickly transformed into sodalite around 

800°C (Fig. 1C). For the glass-containing sample, those new peaks persisted (Fig. 

2D). These phenomena will be examined further in future experiments. 

B 

c 1% 

- Zeolite A, Ambient 

Zeolite A, 2 kbar, rm T 

Sodalite, 2 kbar, 8OOC 

400 500 600 700 800 900 1000 1100 1200 

Channels 

Figure 1. X-ray spectra of pure zeolite A. 

Major peaks labeled in A. Same intensity 

scale as in Fig. 2. 

B 

C 

* 

Zeolite A +glass, 2 kbar, rm T 

0.1 mm from NaCl 

Zeolite A + glass, 2 kbar, rmT 

0 2 mm from NaCI 

400 500 600 700 800 900 1000 1100 1200 

Channels 

Figure 2. X-ray spectra of zeolite+glass.

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3 

Strength of the Subducted Slab: Implications for Deep Focus Earthquakes 

* 

X17B1 

I - I I 

D. J. Weidner, J. Chen, J. Ando. and Y. IVu (CHiPR, SUNY at Stony Brook) 

The strength of the material of the transition zone at the pressures and temperatures 

appropriate to subduction have been determined in the laboratory using both 

the DIA and T-cup multi-anvil pressurizing systems and synchrotron radiation at 

the X17B1 wiggler port at the NSLS. 

The measnrement technique consists of several steps: 1. A loose powder sample 

is used in the stndy. The deviatoric stress is generated by the stress concentrations 

between grains. Typically, in the elastic region, (al - u3) = 1.5 times the pressnre 

on loading. As the yield point is obtained, the tlifferential stress falls below this 

value. 2. The differential stress is monitored as a fmction of time by recording 

diffraction spectra every 30 seconds after heating to the desired temperature. This 

tirne dependence reflects the effective power law for the stress release process. The 

tirne interval varies from an honr to a few days. 3. Several recovered samples are 

examined with TEhI to define the flow mechanism. This methotlology is lirnited to 

relat,ively snlall plastic strains (a few percent) antl the threstloltl deviatoric stress 

that can be observed is of the order of 0.1 GPa. These data have been obtained for 

the major phases of the mantle including olivine, watlsleyite, ringwoodite. ~najorite 

rich garnet, arid perovskitc. Both 'wet' antl dry samples of the olivine series l ~tx~ 

been studied. 

Requiring a storage capacity of 0.1 GPa for 100 years as a criterion for a seisnog 

genic region, we cor~clutle that olivine cannot sustain earthquakes clccper than 

300 krn in all hut the coldest sl~bduct,ing slabs owing to the ternperatnre indncetl 

weakening. Transition zone ruincr;tls, on the other 11;tntl, being much stronger, can 

store the necessary strain energies at temperature expected lwtween 400 and 700 

km for even relatively hot slabs. Thcsc res~llts suggest that the hirnotlal tlistributiori 

of earthqnake activity with tleptl~ is simply n rcflcction of the strength clepentlence 

of thr stable phases and thus does not rcql~irc different triggering n~echanisrn for 

mrthqnakes above and helow 400 krn. 

This work Ins supported ty the SSF under a grant to the Center for High Pressure 

Research and by the DOE under contract number DE-XC02-76CH00016 to the TSLS. 

The Rheological Study of "Super Dry" Forsterite at High Pressure 

and Temperature I X17Bll 

Y. Wu, D. J. Weidner, J. Liu, M. Vaughan and J. Zhang (CHiPR. SUNY at Stony 

Brook) 

The variation of the differential stresses of ''super dry" forsterite with pressure, 

tem~erature and relaxation time was studied using - the DIA tvpe . cubic anvil appa- 

- 

ratn; at the X-17B1 beam line. 

Before the ex~eriment. the svnthesized ~olvcrvstalline forsterite hIa2Si04 mas 

ground to fine p&dcr, then heatkd at 12000k f& 20 hours to dehydrate.-lye call the 

forsterite after this treatment "super dry" forsterite. Following this treatment, the 

sample was stored in an oven at 120°C until the experiment. During the experiment, 

the powder sample was first compressed to 9 GPa at room temperatnre, then heated 

up gradnlly to 800°C. By analysis the peak broadening, we get the tlifferential strains 

of the sample. 

Onr priliminary result shows that the "super drv" forsterite reached yield point 

around 3 GPa at room temperature. The differential stress increased slowly with the 

i~lcreasing pressnre. The room temperature behavior is consistent with ow earlier 

results(IVn, Y., etc.,1996). Urltler the 9.4 GPs confining pressnre, me measured the 

differential strain at 200°C, 40O0C, 500°C. 600°C. 700°C antl 80OoC. \\-e can see 

the differential strain tlecrcasctl with the increasing ternperatnre. At the specific 

tempcratnre, the strain decreased monotonically with the relaxation time, first very 

fast, the became slower. These behaviors are also similinr to our carlier results (%I, 

Y., etc. 1996). However, the "super dry" sample appears to be significantly strongrr 

than the unt,reatetl sample. Fnrther data an;tlysis is still in progress. 

Figure 1. Strain in "super dry" forsterite as a fnnction of time.

( Hard-X-ray Study of Single Crystal Superconducting LazCu04+~ * 1 X17B1 1 I Room Temperature Compression of CdO 1 X17Rl 1 

X. Xiong, D.P. Scarfe, S.C. Moss, A.J. Jacobson, W.J. Zhu, P.H. Hor (U. of 

Houston), P. Wochner (BNL) 

A single crystal of LanCu04.08, annealed at llO°C was studied in a high energy 

diffraction experiment at beamline X17B1 using 7lkeV photons. The crystal was 

charged by electrochemical intercalation. Two orthorhombic phases were observed 

within the studied temperature range (180-310K) in this single crystal. The major 

orthorhombic phase, with ~ 90% volume fraction, transforms from a Fmmm phase 

with random Cu06 tilts to a stage-4 phase [1,2], where the Cu06 tilts are ordered 

along the c-axis, at or below room temperature in a second-order fashion. The 

minor orthorhombic phase shows a larger orthorhombicity with 2(b-a)/(a+b)=0.019 

and has, therefore, a higher oxygen content. The integrated intensity of the staging 

satellites was found essentially to be linearly dependent on temperature from slightly 

below 300K to 180K as previously found by Ref. 2. Interstitial oxygen layering 

was observed for the first time in a more straight forward way than through the 

CuOs tilt reversal at oxygen interstitial layers, which is expressed in the Bmab 

staging satellites. This oxygen ordering was documented by the appearance of 

(0,0,lf 0.65) satellites at room temperature even in the absence of the tilt-staging 

Bmab satellite peaks. These new satellites are thought to be produced by a periodic 

lattice expansion in c-direction induced by the interstitial oxygens. They are poorly 

correlated in c-direction as can be seen from the broad linewidth of the longitudinal 

scan of the (0,0,4-0.65) satellite in the inset of Fig.1. The rocking scans (Fig. 1) 

of the (0,0,6f0.65) satellites are identical to the parent (0,0,6) Bragg peak. The 

broad FWHM is either due to a small domain size of the ordered regions or a 

broad distribution of oxygen staging-layer separations or both. A broad distribution 

would be consistent with our model of the in-plane oxygen ordering [I], which 

occurs at ~200K for an oxygen concentration of --0.05-0.06. Further experiments 

will investigate the temperature and Q-dependence of these new satellites. These 

studies should give new insights in the driving mechanism for this oxygen layering. 

References [I] X. Xiong et al., Phys. Rev. Lett. 96, 2997 (1996); P. Wochner et al., 

J. Superconductivity 4, 367 (1997). [2] B.O. Wells et al., Z.Phys.B 100, 535 (1996). 

Figure 1. Rocking scans of the (O,O,6f 0.65) satellites and the fundamental (006) 

reflection. The inset shows the longitudinal scan of the (0,0,4-0.65) satellite. 

td CL * This work was supported at Houston by the TCSUH, the MRSEC and the NSF on 

DMR-9208420, at BNL support is from the U.S. DOE Contract No. DE-AC-02-76CH00016. 

J. Zhang (CHiPR, SUNY at Stony Brook) 

CdO has the NaCl structure at ambient conditions and at pressures at least up 

to 30 GPa. From previous compression study of Drickamer et al. (1966), CdO 

was found to have an anomalously high value of the pressure derivative of the 

bulk modulus (Ko=9) compared to all other NaC1-type oxides (Ko=3.3-4.1). In 

addition, compressibility of CdO decreased with pressure more rapidly than would 

be predicted for ionic compounds, whereas all other NaC1-type oxides were typically 

ionic in binding. 

In view of the fact that the compression data in the work of Drickamer et al. 

(1966) were considerably scattered in the P-V space, here we carried out in-situ 

X-ray diffraction on CdO using a DIA-type multi-anvil apparatus. The volume 

measurements were made up to 8 GPa at room temperature; all data were collected 

after quench from 800 C to minimize nonhydrostatic stress built up during room- 

temperature compression or decompression. Due to the limited pressure range of 

the current experiment, KO could not be defined well and was thus fixed in the data 

analysis. For Ko=4 and &=9, we obtained KO = 150(2) GPa and KO= 137(2) 

GPa, respectively. In comparison, Drickamer et al. (1966) obtained Ko=108 GPa 

and Ko=9 from the compression data up to 30 GPa. The present results thus show 

a compressibility that is more than 25 percent smaller than that from previous 

work. Therefore, one can make a stronger statement that the binding in CdO is 

not entirely ionic in comparison with the classic Born-Mayer prediction. 

Drickamer HG, Lynch RW, Clendenen RL and Perez-Albuerne EA, X-ray diffrac- 

tion studies of the lattice parameters of solids under very high pressure, Solid State 

Physics, 19, 135-229, 1966.

, 

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Comparative Compressibility of Calcite-Structure Carbonates X17B1 Unidirectional R~Iicrobeam Radiation Therapy of Rats Bearing Sub- 

J. Zhang and R. J. Reeder (CHiPR. SUNY at Stony Brook) 

X17B2 

For carbonates of the calcite structure, experimentally measured bulk moduli on 

NiC03, hIgCO3, CoC03, FeC03. AInC03. and CaC03 have been found to deviate 

from empirical predictions, in the sense that substitution of alkaline earth elements 

by the 3cl transition metals yields a different bulk modulus-volume relationship (1.: 

2.). Here me report new compression data on ZnC03 and CdC03 from in-situ X-ray 

diffraction, which, in combination with our previous results, completes a systematic 

study of compressibilities for all calcite-structure carbonates. As known from earlier 

work. the bulk moduli of the 3cl transition metal carbonates show an inverse correlation 

with room-pressure R'I-0 bond length and volume that is linear. hlgCO3, 

however, plots well below the trend, and CaC03 slightly below. One particular 

focus of this work is the contribution of the crystal field to the bulk modulus. No 

crystal fieltl effect beyond that reflected in the ionic radii is observed among the 

3d transition metal carbonates, since ZnCO3 and XInC03 are colinear with NiC03, 

CoCO3 and FeC03. Notably, the bulk moduli of ZIICO:~ and CoCOs are essentially 

identical, as are their ambient h1-0 bond lengths and volumes. The bulk motlulus 

of CdC03. whose ambient h1-0 borltl length ant1 \~lumc arc only slightly srnaller 

than those of calcite, is more than 30 GPa greater than that of calcite, and falls 

about 1.5 GPa above the trend of the 3tl transition metal carbonates. Hence, ncith~r 

bond-length (or volurne) nor crystal-field effect can account for the observed bulk 

nlotluli for the complete set of calcite-structure carbonatrs. Systematic behavior 

appears to be linlitetl to subset,s of carbonates whose metal cations share particular 

character of their valence electron, e.g., s-type vs. Rtl vs. 4d shclls. 

1. Zhang .J and Reetler R.7, Equation of State of Calcite-Structure Carbonates, 

NSLS ilctivity Reports, P. B-1-47. 1996. 

2. Zhang .J and Reeder R,J, Cornparative cornpressibilities of the calcite-structure 

carbonates. AGU Spring LIeeting, 1997. 

cutaneous 9L Gliosarcoma Tumors: Relevance to Radiotherapy of 

Craniospinal Tumors in Humans 

F. A. Dilmanian, X. Y. Wu, B. Ren, A. Z. Diaz. hI. Kershaw? G. Le Duc, D. T. 

Lombardo, P. L. hIicca, kI .RI. Nawrocky, D. N. Slatkin, F. Telang (BNL), W. C. 

Thomlinson, Z. Zhong (NSLS), and J. C. Allen (Beth Israel hled. Center) 

Microbeam radiation therapy (RIRT) is an experimental method that uses parallel 

arrays of microplanar beams. each about 30 pm wide and millimeters-to- centimeters 

long, with about 50-100 pm apart center-to-center spacing[l]. hIRT studies 

at the NSLS's X17B1 beamline showed two effects for unidirectional rnicrobeam 

irradiations. First, they have extraordinary tissue-sparing effects in the normal tissues 

of rats [I], gerbils, rabbits, and cluck embryos; they do not cause necrosis in 

the brain of rats at doses several times the threshold for direct ncuronal death, 

estimated to be 360 Gy in the cerebrum. Second, they have a preferential turnorkilling 

effect in rats bearing SL gliosarcoma (SLGS) brain tumors. The latter effect 

may reflect important tlifferences in the post-hIRT regeneration mechanism in the 

vascular entlothelial cells of norrnal and tumor tissues. 

Eight rats that had been inoculated subcutaneol~slv with SLGS cells close to 

their cervical spinal cortl twelve clays earlier were irradiated with ur~itlircctior~al 

microbeams anteroposteriorly through their pharynx antl spinal cortl; the animals 

faced the beam with its central anteroposterior body axis at 65 elevation. The inslice 

skin-entrance dose was about 200 Gy antl the beam's width was 27 m. The 

center-to-center beam spacing was 75 rn. The array's er~velope mas 20 rnnl x 20 mrrl 

for (i rats, 23 nlm x 23 mrn for the 7th, antl 26 rrrm x 26 mrn for the 8th. Forty 

eight days later the tumors had disappeared in 5 rats and mere barely visible in 

two others. One rat died 42 clays after irradiation. Necropsy showed tlemorrl~agic 

congestion of the lungs and the liver, mainly outside the irradiation field. The 

tracheal antl the esophageal rnucosal linings, which were largely in the radiation 

field, appeared nornlal. The pericartliurn also appeared norrnal. There was no 

pcricartl~al hemorrhage. The etiology of t,he pulmonary antl hepatic lesions are not 

known, but might have been cause by congestive heart failure. It is possible that 

~novemcnt of the rat during irratliation precipitated in this condition. 

lye plan to upgrade the 1IRT irratliation systml at X17B. antl expand preclinical 

XIRT st~~dies, preparing for Phase I human studies with the following goals: 

a) treating children with t~lmors of the ccntral nervous system. antl b) palliating 

rnetastases to the spinal cortl antl brain from primary tnmors such as brext or lung. 

Lnitlirectional 11RT may be appropriate for the following reasons: a) for incidrnt 

doses below the threshold for direct ncuronal-crll killing. it appears harmless, even 

in developing animals such as duck embryos. which are far more radiosensitive than 

adults. b) it does not damage the rat's spirlal cortl, which is more ratliosensitive than 

the cerebrum. c) it appears safe when irradiating large values. d) it is insensitive to 

the subject's positioning in the beam. e) dose fractionation may prove to be unnecessary. 

n-hich \vould be convenient for children and metastatic patients. and f) even 

with snboptinlal irradiation parameters. 1IRT's palliative effects are remarkable. 

lye thank K.-4. Bonti. J.-4. Coderre. D.D. Joel. C. Rissland. and -1.D. \Voodhead 

for assistance. Research supported by the Office of Biological and Environmental 

Research. DOE. 

[I] D.S. Slatkin. et al.. Proc. Satl. ;\cad. Sci. US=\ 82. 8783-8787. 1995.

Xenon K-edge Imaging With a Monochromatic CT Scanner to Se- 

lectively Image Fat in Rats: Relevance to Compositional Imaging 

of Carotid Atherosclerotic Plaques* 

F.A. Dilmanian, X.Y. Wu, B. Ren, X. Huang, D.N. Slakin, (BNL), W.C. Thomlin- 

son, Z. Zhong (NSLS); T.M. Button, M.J. Petersen (SUNY at Stony Brook), and 

L.D. Chapman (ITT) 

Carotid artery atherosclerosis is a major cause of stroke. Although carotid artery 

stenosis is a risk factor, the majority of patients with stenosis do not experience a 

stroke. Recent evidence suggests that a certain proportion of the main components 

of carotid atherosclerotic plaques, i.e., fat/cholesterol, fibrous and calcified tissues, 

carry larger risks of stroke. The monochromatic CT system at X17B2 called MECT 

(multiple energy computed tomography) [l] may be able to separate these compo- 

nents and allow more accurate selection of patients for carotid endarterectomy. For 

this, MECT will be used in two energy-selective modes a) a dual-energy quantita- 

tive CT (DEQCT), in which 40 keV and 100 keV image are processed to separate 

the image of the low-Z tissue (the non-calcified one) and the intermediate-Z tissue 

(the calcified one), and b) xenon K-edge subtraction, that relies on xenon's large 

solubility in fat and the large gain in contrast in the xenon image obtained by tuning 

the monochromatic beam energy just above the K-edge [I] to quantify fat. 

In the following experiment MECT was operated in the planar (i.e., radiography) 

mode. A 400-g Zucker rat, was given a mixture of 50% xenon and 50% air for one 

hour. It then breathed air for an hour to allow the washout of xenon from the 

lean body mass. The rat was positioned anteroposteriorly in the beam in a prone 

position, tilted upward (i.e., nose-up), and imaged by moving it vertically in the 

path of MECT's fan-shaped beam. Images were acquired at two beam energies, 

34.40 keV and 34.72 keV, which bracketed the K-edge of xenon (34.56 keV). The 

spatial resolution was improved by taking two sequential images with the rat shifted 

laterally by half the detector's element spacing between the two, and combining 

them. Fig. 1 shows the above the K-edge (left), below the K-edge (center), and 

subtracted (right). Because of an apparent small movement of the rat between the 

images at the two energies, they had to be slightly shifted and rotated for the best 

match. The fat observed in the subtracted picture is the subcutaneous fat under 

the rat's left shoulder (the rat was imaged in a slightly crooked position) 

[I] F.A. Dilmanian, et al., Phys. Med. Biol. 42:371-387, 1997. 

*We thank M. Kershaw and A.D. Woodhead for assistance. Research supported 

by the Office of Biological and Environmental Research, DOE. 

Figure 1. Rat Xe K-edge images. 

Preliminary Experiments on a Mammography Imaging System and 

a Multi-Layer Monochromator for Angiography * 

I X17B2 1 

K. Hyodo, M. Ando (PF), K. Tanioka, R. Mochizuki (NHK), H. Mori (Tokai Univ.), 

Z. Zhong and W. Thomlinson (NSLS) 

We have been developing a mammography imaging system using a fluorescent 

screen coupled with a HARP (High-gain Avalanche Rushing amorphous Photo conductor) 

TV camera, which is a photo-tube camera manufactured by NHK (Japanese 

Broadcasting Co.). The camera has a dynamic range of larger than 10,000 and high 

sensitivity. The spatial resolution of 30 microns, with the view size of 30 mm by 

20 mm, was achieved during the phantom experiments on X17B using a Hi-vision 

HARP TV at 20, 25 and 33 keV. 

We have been developing a multi-layer monochromator to get larger integral intensity 

than that of a Si crystal with lapped surface, whose energy resolution, dE/E, 

is 4.5~10-3. In the case of intravenous coronary angiography using one monochromatic 

energy at above the K-edge of the contrast material, it is not necessary to 

use a Si crystal to get monochromatic x-ray photons. 

The available photon flux is easily increased without increasing the ring current if 

we can use a monochromator which can reflect photons in the range of a few keV. We 

achieved the view size of 30 mm by 60 mm by using a test sample monochromator, 

whose energy resolution was 2.4~10-2, at 33 keV. However, the intensity of the view 

area was not uniform. Further investigation will be needed for the monochromator. 

* Research suported (in part) by the USDOE, Div. of Materials Sciences and Div. of 

Chemical Sciences.

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4 

Dual-energy subtraction imaging utilizing indium as a contrast 

agent 

X17B2 

- I I 

G. Le Duc, Z. Zhong (NSLS), L. Warkentien, B. Laster (BNL hIedica1). and \V. 

Thomlinson (NSLS) 

The purpose of our current work is to establish the minimum detection limit of 

indium contrast agent using dual-energy subtraction imaging above and below indium 

K-edge. Experiments were performed on the X12 and X17B2 beamlines at the 

National Synchrotron Light Source using the same method but with two different 

set-ups. Experiments were first carried out on InC13 solutions, then on V79 Chinese 

hamster cells antl on BALB/c mice excised tumors, labeled with indium. For each 

experiment, several layers of Lncite were placed in front of the phantom to ensure 

a 43 rnm thickness. close to that of a mammography examination. Results were 

the same on X12 antl X17B2. r\s expected, indium-free materials dissapeared on 

subtracted images (water, steel reference and screw). Indium samples mere easily 

distinguishable for the following concentrations: 10-5-2-1 rng/crn2. Smaller concentrations 

were not clearly distinguishable and we were unable to see cell samples and 

tllrnors. To conclutle, the lowest concentration we can irnage is aro~lntl 1 mg/cm2. 

Sl~ch results also suggest that indi~un cor~centration in both cells and tumors is lower 

~ 2 ~ 2 

thatn 0.5 rng/crn? Since the current method is close to optimnrn, we conclude that 

dual energy subtraction imaging using indium to label tumors is not possible uulcss 

the intliuul uptake is increasrd by more thm an ortler of rnagnitutle. 

Contrast Analysis of 2D I\.Ionochromatic X-ray Coronary Artery 

Images * 

I X17B2 I 

Y. Oku (U. for Adv. Studies), K. Hyodo, RI. Ando (KEK). Z. Zhong and 11'. 

Thomlinson (NSLS) 

Intravenous SR coronary angiography is relatively simple and safe so that screening 

looks promising as an application. For clinical use, the constrnction of a compact 

source at hospitals is required. In order to design a system. it is necessary to investigate 

the expected image quality by both simulations and experiments. For 

example, scattering of x-rays and the presence of higher harmonics in the spectrum 

may degrade the quality. 

A two-dimensional imaging system has been adopted for the intravenous SR coronary 

angiography program iri Japan. It has many benefits such as easier tlistirlction 

of coronary arteries from pulmonary arteries and soft tissues because of its rr~otion 

synchronieed with the heart beat and the capability of diagnosis of other heart 

functions such as the rate of blood flow. However, in the 2D mode, scattering of 

x-rays from the patient may cause significant deterioration of image contrast and 

visibility. The scattering can be suppressed by x-ray grids which are cornrnrnonlv 

used at hospitals, b ~ the ~ t inevitable third harmonic cannot he sllppressetl. Since 

the higher harmonics and scattering cannot be distingl~ishetl on the experinlental 

irnage, simulations may he effective to identify their inflnences on the tleterioration 

of the image contrast. \Ve have thus developed a simulation program of 11-TV irnages 

when 2D monochromatic SR x-rays pass thro~~gh an acrylic phantom with an 

artery. 

111 order to verify the irnage contrast calculated hv the sirnl~lation program, experiments 

have bccn carried out. The experiment was (lone at the 517B heamline 

of the NSLS. An asyrnrnetric, lapped silicon (311) crystal acted as t,he monochromator. 

The phanton~ was an acrylic hlock with a hole which imitates a coronary 

artery with diamctcr I - 5 rrirn containing iodine diluted by water to 1 to 10%. An 

image intcnsificr (11) detector was nsed. Untlcr the snnle conditions, simulations 

werr carried out while taking into account the response function of the I1 for the 

photon energy used. The calculated contrast was comp;mxI with the experiment. 

Research supported (in part) by the VSDOE. Div. of \Iaterials Sciences and Div. of 

Chemical Sciences.

A Bent Laue-Laue Monochromator for the Multiple Energy Com- 

1 Beam Harmonics In a Bent Laue-Laue Monochromator I X17B2 1 

X17B2 

puted Tomography Project * 

B. Ren (Med., BNL), Z. Zhong (NSLS), F.A. Dilmanian and X.Y. Wu (Med., 

B. Ren, F.A. Dilmanian, X.Y. Wu, X. Huang (BNL), L.D. Chapman, I. Ivanov BNL), L.D. ~ha~man'and I. 1vanov (CSRRI) 

(CSRRI), and Z. Zhong (NSLS) 

One advantage of a bent Laue-Laue monochromator over the flat Laue-Laue for 

the MECT program (see accompanying abstracts) is the lower beam harmonic con- 

A bent Laue-Laue monochromator is being developed for the multiple energy 

tamination. The harmonic ratio from two bent-Si-CZ crystal was measured 

computed tomography (MECT) program. The present crystal design, a large by the Compton scattering method, using a 1/80" thick Be target tilted to a = 52O. 

Czochralski (CZ) Si plate with thick ribs on the top and bottom, was adopted A Ge detector positioned 90' to the beam measured the scattered beam, while an 

after earlier trials using silicon wafer and smaller, float-zone (FZ), ribbed crystals. Ar-filled ion chamber upstream of the Be target monitored incident monochromatic 

The new system was constructed at CSRRI and BNL. The crystals were Si 

beam, tuned to 41.7 keV. The white beam was filtered with additional 1.6 mm Cu 

with 35.36' asymmetric angle. Both crystals employed Laue diffraction lower case to enhance the harmonic contents. 

to eliminate Laue spot contamination. The crystals were bent by a four-rod bender: From the dynamical theory, the fundamental beam yield increases and the hartwo 

fixed and two adjustable. The ends of each adjustable rod was independently monic beam decreases at the intermediate bending range (3 - 50 m) as the bending 

held by a compression spring. This four-spring configuration allowed efficient re- radius is decreased. Our harmonic-ratio results from Ge detector were, about 20% 

moval of crystal twisting. 

below the predictions, except at p= 11 m, where they were 38% higher. The fun- 

The crystals were positioned in the beam such that the diffraction in each crystal damental beam fluxes measured with Ge detector were 0.3-0.5 of the predictions of 

came from its vertical center. The bending radius of each crystal was determined the code PEPO; the ion chamber results were 0.4-0.6 of PEPO. We suspect that 

by measuring its variation of the Bragg diffraction peak of it against a fixed crystal the non-centered vertical position of slits in the white beam's path was one of the 

as the height of the crystal changed stepwise. Furthermore, the horizontal profile reasons for the low harmonic ratios and low beam fluxes. The imperfect alignment 

of the 14-cm wide diffracted beam was measured at 0.9-mm resolution using the of the Ge detector's nozzle could also reduced the beam flux. 

MECT's linear array detector. A 2-dimensional rocking graph was acquired as the Compared with tuned flat-flat Si crystals at this energy, these results 

angle 82 was scanned. The shape of the rocking curve for each horizontal detector showed 5 - 65 fold reduction of the harmonic ratio, and 8-25 fold increased beam 

channel indicated the degree at which the bending radii of the two crystals matched; flux. These characteristics of the new monochromator should substantially improve 

the flatness of the gray scale's bright zone in the 2-dimensional display indicated MECT's image quality. 

whether there existed twisting, tilting, or 'beam smiling effect' in the system. Much 

effort were spent to remove the twisting and beam smiling. An example of the 2- 

dimensional rocking graph is shown in Fig.1. The bending radius was 4.8 m for the 

first crystal and 4.9 m for the second. The beam size was 140 mm x 2 mm, and the 

beam energy was 41.7 keV. 

The overall shape of the rocking graph was straight except for some small wiggles 

caused by the local crystals non-uniformities. The 1-dimensional rocking curves, 

relating to the central and ends positions of the fan beam are plotted in Fig. 2. 

The flat-top shape in all these three curves, particularly at the relatively large 

beam height of 2 mm, indicate that the bending radii matched over the entire 

width of the crystals. The beam stability was tested at the monochromator's tuned 

configuration. The horizontal beam profile, normalized to that a certain time, was 

stable within 0.1% for two minutes period. This stability is markedly better than 

that of the previous flat Laue-Laue monochromator of the MECT system. 

* We thank T.S. Dickinson, N.F. Gmiir, J.B. Hastings, A. Lenhard, C. Schulze, 

N.C. Satterley, D.P. Siddons, W.C. Thomlinson, G.M. Vanderleski, S. Wang, and 

M.H. Woodle for assistance. Research supported by the Office of Biological and 

Environmental Research, DOE. 

w 

+ Figure 1. Rocking graph Figure 2. Rocking curves 

Cn 

Figure 2. The fundamental and har- 

Figure 1. Compton scattering setup. monic beam fluxes, and their ratio.

tJ 

I--L 

rP 

G? 

Energy Response Measurements of Dental CCD Sensor Systems 

Using R~lonochromatic X-Rays * 

K. Tokumori, S. Kanda, F. Toyofuku (Kyushu Univ.), K. Hyodo. M. Ando (KEK), 

Z. Zhong and W. Thomlinson (NSLS) 

Several digital dental imaging systems have been developed by manufactureres 

of intraoral radiology equipment. They have the following advantages: no film development 

process; reduced radiation dose: digital image processing. This study 

investigated the energy response of CCD systems by using monochromatic synchrotron 

x-rays. 

The energy responses of two types of CCD digital systems were studied: a Sens-A- 

Ray system without a scintillator (Regam hledical Systems. Sweden) ancl a dental 

visllal x-ray imaging system (hIatsushita Industrial Eq. Co.) with a scintillator 

(DVXIS). Monochromatic x-rays were reflected from a Si crystal to expand the 

bearn to about 35 mm (w) x 40 mnl (h) at energies of 28.8, 35.5, 45, antl 55 keV. 

The dose rate was varied at each energy by use of Lucite absorbers between 10 

antl 24 cm thick. The exposure tlose was measured with a shallow type ionization 

chamber (Victoreen). A short exposure time of 0.1 sec was nsed to minimize the 

CCD dark current effect. 

The pixel values for a series of measurements at varying energies antl exposme 

doses were averaged. The valne of the pixel value, for a fixed tlose, increased with 

decreasing energy. As the absorber dose rate tlecreased with the thicker absorbers, 

the ratio of the third order to the first order harrnor~ic increased. The ratio estimated 

from the Lncite linear attenuation coefficient and the known white bearn spectrum 

was very large. However, the inflnence of the third ortlcr harmonic x-rays on the 

Scns-A-Ray \vas about 30% at 28.8 keV antl less than .5% at othcr energies. These 

small ratios were tlne to the low sensitivity of Si(thc main element of the CCD) at 

thc energips of the harmonics. 

* Research supported (in part) by the USDOE Div. of IIaterials Sciences and Div. of 

Chemical Sciences. 

In Situ Identification of Natural Diamond Inclusions with Syn- 

X17B2 X17C 

chrotron Microdiffraction 

P. G. Conrad, R. J. Hemley> H. K. Mao, L. W. Finger, J. HLI. J. Shu (Carnegie 

Inst.), B. Harte, h.1 Hutchison (U. of Edinburgh) and J. Harris (U. of Glasgow) 

We have used a white synchrotron beam at X17C to obtain energy dispersive x-ray 

diffraction from natural diamond inclusions in situ, i.e., non-destructively. These 

detrital diamonds, from the Siio Luiz deposit in Mato Grosso, Brazil, are of geo- 

physical importance because they are thought to have originated in the earth's lower 

mantle. Electron microprobe analysis (EPhIA) on other Siio Luiz specimens indi- 

cates the chemical compositions of lower mantle phases such as (hIg,Fe)O, ilIgSiO3 

antl CaSiO3 together with lower pressure phases aluminous garnet ancl majorite. 

Because sample preparation for EPhIA necessitates destructive polishing of the 

diamonds to expose the inclusions, any confining presswe signatures within the di- 

amonds will be lost along with textural information. In situ structural analysis is 

an important advance in the study of crystalline inclnsions within diamontls and 

other xenoliths because it enables us to examine samples of the Earth's mantle that 

are presumably free from alteration or contamination. 

Each diamond is mounted on a chi circle, the physical dimensions of which con- 

strain the range of omega values we may search using single crystal procedures. By 

rotating the two angles x and w, we can search for single crystal reflections which 

will appear as peaks in an energy dispersive pattern for a specific x antl w when the 

diffraction condition is satisfied. After aligning the inclusion within the path of the 

X ray beam, we can acljust the inclusion's position with respect to the detector to 

optimize intensity of the diffracted beam. \Vith the assistance of two Kirkpatrick- 

Baez x-ray focusing mirrors, wc can achieve a very srnall beam size (about 11x15 

microns). This is useful for searching for tliffraction in very small inclusions that 

are close to one another. 

A typical search for tliffraction peaks takes us through an interval of -20

Disorder Induced Phase Transition of the Rare Gases in Porous Vycor 

Glass.* 

D. W. Brown, P. E. Sokol ( Penn. State U.) and S. N. Ehrlich (Purdue) 

Recently a great deal of effort has been expended to study the effects of finite 

size and confinement on the properties of simple gases, liquids, and solids, achieved 

by adsorption into mesoporous materials. Examples of such mesoporous materials 

include sol-gel glasses, porous Vycor glass, zeolites, and of course rocks and cements. 

These porous media are of technological interest in fields such rheology, tribology, 

and materials research. The adsorbed samples provide a platform for fundamental 

studies of surface effects as well as molecular interactions with surfaces which is 

unattainable in bulk samples. While many measurements of macroscopic quantities 

such as the heat capacity of confined materials have been reported few microscopic 

measurements are available. To explore the effects of confinement on the structure 

of the rare gas solids we have carried out X-ray diffraction measurements of the 

structure of Ar and Kr confined to porous Vycor glass as a function of temperature. 

Bulk Ar and Kr crystallize into the fcc structure at 84 K and 116 K respectively 

and remain in this phase to absolute zero. At high temperatures confined Kr and 

Ar solidify into a disordered close packed structure as shown for Ar in figure 1. At 

low temperature the (200) peak along with sharp (resolution limited) companions 

to the high temperature peaks appear indicating a solid - solid phase transition that 

is not present in the bulk phase diagram. W scans reveal the nature of the sample 

responsible for the low temperature peaks to be large grain poly-crystallites rather 

than powder as is seen at high temperature. The inset to figure 1 shows the (200) 

peak with the cell at different orientations exemplifying the non-powder nature of 

the sample. Similar scans of Kr show analogous behavior. Figure 2 tracks the 

amplitude of the (200) peak as a function of temperature on warming. The (200) 

peak, characterizing the fcc structure, is seen to disappear at a reduced temperature 

of approximately 0.50 for both Kr and Ar. In summary we have shown that disorder 

induced through confinement of Kr and Ar to the pores of Vycor glass stabilizes 

a novel structure, disordered close packed, as well as spurs a solid - solid phase 

transition that is not present in the bulk phase diagram. * (Work was supported 

by the American Chemical Society Petroleum Research Fund under 31097-AC5 and 

U.S. DOE under DE-FG02-85ER45183.) 

Figure 1. 

37 K 

55 K 

85 K 

Vycor 

Figure 2. 

X18A 

I The Structure of Rare Gases in Porous Vycor Glass * I X18A I 

D. W. Brown, P. E. Sokol (Penn. State U.) and S. N. Ehrlich (Purdue U.) 

Recently a great deal of effort has been expended to study the effects of finite 

size and confinement on the properties of simple gases, liquids, and solids, achieved 

by adsorption into mesoporous materials. Examples of such mesoporous materials 

include sol-gel glasses, porous Vycor glass, zeolites, and of course rocks and cements. 

These porous media are of technological interest in fields such rheology, tribology, 

and materials research. The adsorbed samples provide a platform for fundamental 

studies of surface effects as well as molecular interactions with surfaces which is 

unattainable in bulk samples. While many measurements of macroscopic quantities 

such as the heat capacity of confined materials have been reported few microscopy 

measurements are available. To explore the effects of confinement on the structure 

of the rare gas solids we have carried out X-ray diffraction measurements of the 

structure of Ar and Kr confined to porous Vycor glass as a function of temperature. 

Bulk Ar and Kr crystallize into the fcc structure at 84 K and 116 K respectively 

and remain in this phase to absolute zero. The freezing points of the confined Ar 

and Kr, denoted by the appearance of sharp diffraction peaks, were found to be 65 

and 100 K respectively, with the melting points of 70 and 106 K being somewhat 

higher. Figure 1 shows the scattering from the empty cell, liquid Ar and solid 

Ar at high and low temperature. At high temperature 55 K peaks corresponding 

to the fcc (Ill), (220), (311) , and (222) are apparent while the (200) peak is 

absent. This is characteristic of a disordered close packed structure. The scattering 

from confined Kr follow a similar pattern. At low temperature the (200) peak 

along with sharp (resolution limited) companions to the high temperature peaks 

ppear indicating a solid - solid phase transition that is not present in the bulk 

phase diagram. W scans reveal the nature of the sample responsible for the low 

temperature peaks to be large grain poly-crystallites rather than powder as is seen 

at high temperature. The inset to figure 1 shows the (200) peak with the cell at 

different orientations exemplifying the non-powder nature of the sample. Figure 2 

tracks the amplitude of the (200) peak as a function of temperature on warming. 

The (200) peak, characterizing the fcc structure, is seen to disappear at a reduced 

temperature of approximately 0.50 for both Kr and Ar. In summary we have shown 

that disorder induced through confinement of Kr and Ar to the pores of Vycor glass 

stabilizes a novel structure, disordered close packed, as well as spurs a solid - solid 

phase transition that is not present in the bulk phase diagram. * (Work supported 

by the Amer. Chem. Soc. Petro. Research Fund under 31097-AC5 and U.S. DOE 

under DE-FG02-85ER45183.)

X-ray Scattering Studies of Liquid Crystalline Polymer Structure 

Under Shear* I X18A I Structural Studies of Self-Assembled Alkynyl and Organometallic 

W. Burghardt, D. Cinader, V. Ugaz (Northwestern U.): P. RIather and A. Romo- 

Uribe (USAF) 

We have performed experiments at X18A under two general user proposals; both 

involve use of x-ray scattering to study th eability of applied shear flows to induce 

macroscopic molecular orientation in liquid crystalline polymers [LCPs]. This 

structural information is then used to provide insights into the rheological plienomena 

in these complex fluids. The first set of experiments focused on the structural 

origins of so-called "Region I" shear thinning, an anomaly observed in LPCs at 

low shear rates In one model system, neniatic solutions of poly(benzv1 glutamate) 

[PBG] in m-cresol, Region I is only observed beyond a critical concentration. In 

situ x-rav scattering meas~~rernents reveal that Region I is caused by the formation 

of a hexagonal phase, and is not a characteristic feature of nematic LCP rheology. 

Figure 1 shows the connection between rheological behavior antl structure, showing 

equitorial scaris of scattered intensity obtained during shear flow for four solutions 

at difference concentrations, as compared with intlependent measurements of rheologv 

in the same soll~tions. As concentration increases, a shart pcak associated with 

t,he hexagonal phasc grows at the extense of the tliffi~se pcak attributed to lateral 

packing correlations in the nematic phase. 

In atltlitiori to establishing the origins of Region I shear thinning in this system, 

we have also observed that application of shear at high rates is able to effect a 

transition frorrl the I~exagonal phase back to the nematic phase. 

The second set of cxpcrimcnts lvas targeted at extensior~ of ow room temperaure 

studies on LCP solutior~s to LCP melts, which require elevated tempcratl~rrs. In 

collaboration with ow colleagurs from Phillips Laboratory, we performed experimrnts 

on a nurnber of thermotropic LCPs using a melts shear cell c~~stornizctl for 

~~setl in x-rav scatterirw c, cxntri~nr~its. *\York supported by NSF Grant CTS-9457083 

L 

antl a ~ u~dnt Young Faculty A\vard. 

Figure 1. (a) Radial scattered intensity scans along equator measured under shear 

at a rate of 1 ljs. (b) Steady shear viscosity vs. shear rate for the same solutions 

as in (a) 

/ X18A I 

Thin Film Materials 

Ashok K. Kakkar (LIcGill U.) 

An evaluation of the structure of molecularly self-organized thin films containing 

long chain rigid-rod alkynyl and dialkynyl chromophores via exclusive pi-pi interactions. 

is an essential and crucial step for any device applications based on such 

systems, in the field of optoelectronics. conductivity, photoresists etc. We have now 

established an efficient synthetic methodology to such supramolecular structures 

molecularly self-assembled on inorganic oxide surfaces.' i\Ionolayers of a variety 

of alkynyl and dialkynyl chromophores with varied chain lengths and acetylenic 

microstructures mere prepared on single crystal silicon wafers (1" x 3" single side 

polished, 95-105 mils thick). These thin filrris mere first analyzed by in-house ellipsometry, 

followed by X-ray reflectivity studies on X18A beamline at NSLS synchrotron 

facility. In general, there is a good agreement in the thicknesses from X-r,z?l 

reflectivity and ellipsometry meas~rements.'~'' IVe have begun a study of the surface 

topochemical polymerization in these oriented alkynyl mono- and mnltilayered 

structl~res. Two of the ma.jor requirements for the latter process arc orientation of 

alkyriyl chromophores at an angle to the surface, arid uniformity. X-ray reflectivity 

studies in combination with ellipsometry and FTIR-ATR are invaluable techniques 

to address these issues. IVe have also been interested in deterrriiriing the cfFrct of 

X-rays on the alkynyl thin films, since alkynyl chrornophores are subject to radiation 

darnage. In our fi~t~~re trips to BNL, we shall concentrate on the study of the 

structure of dialkyrivl thin film assemblirs before antl after topochernical polynirrixation, 

to uritlcrstand the mechanistic details of this phenomenon, and to develop 

a rational approach to rnntcrials hasrtl on alkynyl thin film. \\.P have also begun to 

look at the effect of rnolccdar order on the activity and selectivity of heterogcnizetl 

homogeneous catalysis. A variety of organon~etallic thin films are self-asserttbletl 

on flat surfaces and after establishing thr degree of order in these thin filrus, their 

catalytic activity mill be evaluated antl cornpared with solr~tiorl analogs. Our prclirninarv 

work on such thin films has sho\vn that a positive role is played by the 

orientation of surface hourid organometallic species in catalysi~."~~ 

1. C.hI. Yarn, A.K. Kakkar. .I. Chem. Soc., Chenl. Commun.. 1995, 907-909. 

2. C.hI. Yarn, S. Tong, A. Dickie, X.K. Kakkar. X1.A. \17hitehead, A. Richter arid 

Pulak Dutta, Can. ,I. Chern., Special Issue. Invited Paper. 1998. 

3. C.11. Yam. S. Tong, X.K. Kakkar. A. Richter. Pulak Dl~tta, manuscript in 

preparation. 

4. A1.G.L. Petrucci. A.K. Kakkar. .T. Chem. Soc.. Chem. Commun.. 1905. 007- 

909. 5. A1.G.L. Petrucci. X.K. Kakkar. Organornetallics. submitted for p~tblication.

Role of Oxygen Partial Pressure in Texture Development of Lead 

Zirconate Titanate Thin Films * I X18A I I Thermal Diffuse Scattering in Indium * 

J.L. Norton, E.B. Slamovich, and G.L. Lied1 (Purdue U.) 

The formation of a transient lead-platinum intermetallic phase, Pt3Pb, is found 

to be instrumental in the development of (111) orientations of Pb(Zr0.60Ti0.~0)03 

i 

"60 

i 

40 PZT") thin films derived by metallo-organic decomposition (MOD) on 

Ill -oriented Pt-coated Si substrates. The PtsPb phase is found to form in a 

111 orientation, which then enhances the (111) orientation of 60140 PZT. This 

phase was investigated by using a combination of slower heating rates (25 "Clmin) 

than those used in "rapid thermal processing" (RTP) processes, and controlled partial 

pressures of oxygen. It was found, by switching the process atmosphere from 

oxidizing to reducing (relative to Pb), that it is necessary that the Pt3Pb phase 

be present at the time of PZT crystallization but should not be present in such 

quantity that the growing film is lead-deficient, leading to the formation of a large 

amount of pyrochlore. 

Figure 1. Three fold orientation of 

the intermetallic phase PtsPb formed on 

(111) oriented Pt is consistent with (111) 

orientation of the intermetallic phase. 

The (311) poles are shown on the left 

and the (100) poles on the right. 

P w * This work is supported by U.S. DOE 

h 

co Grant No. DE-FG02-85ER45183 

A. W. Overhauser, A. S. Bakulin and S. N. Ehrlich (Purdue University) 

Single-crystal x-ray diffraction on indium led to the discovery of 118 half-integral 

hlcl reflections at room temperature. In order to determine whether these unex- 

pected diffraction peaks arise from a broken symmetry or some other cause, their 

temperature dependence was measured between 20 and 200K on beam line X18A 

at the NSLS. It was found that the "satellite" intensities were essentially linearly 

proportional to Tj so their origin can be attributed to thermal diffuse scattering 

from the lowest phonon mode near the (1/2,1/2,1/2) points of the Brillouin zone 

boundary. A complete lattice-dynamics calculation is required (and is in progress) 

to investigate whether this satellite-like structure requires the presence of a spin- 

density-wave broken symmetry or not. 

Figure 2. * This work is supported by U.S. Department of Energy Grant No. DE-FG02- 

85ER45183.

Binding Energy of Aligned Glass on Thin Films of Liquid Crystals 

Chevron Structure in the Smectic-A Phase of the Liquid Crystal 

I I X18A I * 1 ~ 2 4 

D. E. Silva, P. E. Sokol, J. S. Patel (Penn. State U.), and S. N. Ehrlich (Purdue 

u.1 

Liquid crystals are vital in industry today, being used for liquid crystal displays 

in such electronics as calculators and laptop computers. However, the structure, in 

its various phases, still is not completely known and is worth further study. 

We have begun to study the effects of surface preparation on the structure of the 

Smectic-A (SA) phase of the liquid crystal, hI24. Number 1 glass is spin coated 

with three parts ACT600 to one part AL1051 ancl then baked to evaporate the 

solvent. The glass is rubbed to give a preferred orientation to the glass. The glass 

is then cut ancl glued 30 microns apart from one another such that the polymer is 

on the inside of each piece of glass antl oriented in the same direction with respect 

to one another. The liquid crystal is heated into the liquid phase ancl the capillary 

forces of the glass are used to draw the crystal between the two glass plates. Using 

optical measurements, it is easily seen that surface alignment of the liquid crystals 

is accomplished. 

Our sample was heated into the liquid phase (>360K) antl slowly cooled into 

the S,, phase (327.5K-340.0K). X-ray measurements showed the tl-spacing to be 

approximately 32hn close agreement with accepted measurements. It was found 

that as the temperature is drcreased within the S,\ phase, the layers begin to form 

a chevron structure (see appropriate progress report). The figure below shows the 

diffraction peaks as a fimction of k, where k is the hliller index corresponding to the 

rnornentun~ in the planc, prrpentlicular to the glass walls. The dotted line is a scan 

with only the aligrnncnt forces of the glass at work, while the solid line is a scan of 

both the alignment forces of the glass AND a magnetic fieltl. The rnagnetic field 

was created by two rare earth magnets, which were positioned such that the fieltl 

aligned the liquitl crystals in the same direction as the glass. Clearly, the shape of 

the peaks is changed when a magnetic fieltl is introtll~cetl. 

Future work mill inclutle the use of a good electromagnet, so that different magnetic 

fields can be comparetl. This will cnnble the binding energy of the glass to be 

determined. 

Figure 1. This shows the momentum in the plane. perpendicular to the glass walls. 

The dotted line is a plot with the liquitl crystals aligned solely by the glass. The 

solid line is a plot with the crystals under surface alignment and alignment from a 

magnetic field. 

This work supported by the .American Chemical Society Petroleum Research Fund 

under grant So 31097-.-\C5 and V.S. DOE Grant No. DE-FG02-85ER15183 

* I X18A I 



in such electronics as calculators and laptop computers. However, the structure, in 

its various phases, still is not completely known and is worth further study. 


Smectic-A (SA) phase of the liquid crystal, hI24. Number 1 glass is spin coated 

with three parts ACT600 to one part AL1051 and then baked to evaporate the 

solvent. The glass is rubbed to give a preferred orientation to the glass. The glass 

is then cut antl glued 30 microns apart from one another such that the polymer is 

on the inside of each piece of glass and oriented in the same direction with respect 

to one another. The liquid crystal is heated into the liquid phase and the capillary 

forces of the glass are used to draw the crystal between the two glass plates. Using 

optical measurements, it is easily seen that surface alignment of the liquid crystals 

is accomplished. 

Our sample was heated into the liquid phase (i360K) and slowly cooled into 

t h SA ~ phase (327.5K-340.0K). X-ray measurements showed the tl-spacing to be 

approximately 32Ain close agreenlent with accepted measurements. It was found 

that as the temperature is decreased within the S,t phase, the layers begin to form a 

chevron structure. Figure 1 shows the tliffraction peaks as a function of k, where k is 

the RIillrr index corresponding to the momentum in the plane perpendiclllar to the 

glass walls. If the layers stayed perpendicular to the glass \valls, yo11 mo~~ltl expect 

onr peak centered at k=O. The solid line is a scan with the temperat,ure at 340K, j11st 

below the nematic phase. Generally, the layers are perpentlicular to the glass walls, 

but multiple peaks can be seen. The dashed line is a scan with the temperature 

at 334K. The two peaks clearly show an increase in the chevron structure that 

continues to increase at lower temperatures, especially at 31HK (dotted line) where 

the liquid crystal has supercooled. 

hIore complete analysis mill give analytical values to the shape of the momentum 

curves in all three directions: normal to the planes, in the plane and normal to the 

glass, and in the plane antl parallel to the glass. 

Figure 1. This shows the momentum in the plane, perpendicular to the glass walls 

for a number of different temperatures. Sote the increase in the chevron structure 

of the layers as the temperature is decreased. 

\Vork supported by The -American Chemical Society Petroleum Research Fund under 

grant So 31097-AC3 and r.S. DOE Grant No. DE-FG02-85ER45183.

I Competition Between Surfaces in Thin Films of Liquid Crystals * I X18A I 



in such electronics as calculators and laptop computers. However, the structure in 

its various phases still is not completely known and is worth further study. 


Smectic-A (SA) phase of the liquid crystal, M24. Number 1 glass is spin coated with 

three parts ACT600 to one part AL1051 and then baked to evaporate the solvent. 

The glass is rubbed to give a preferred orientation to the glass. The glass is then 

cut and glued 30 microns apart from one another such that the polymer is on the 

inside of each piece of glass and oriented normal to one another. The liquid crystal 

is heated into the liquid phase and the capillary forces of the glass are used to draw 

the crystal between the two glass plates. Using optical measurements, it is easily 

seen that surface alignment of the liquid crystals is accomplished. 

Our sample was heated into the liquid phase (>360K) and slowly cooled into 

the Sa phase (327.5K-340.0K). X-ray measurements showed the d-spacing to be 

approximately 32Ain close agreement with accepted measurements. When rotating 

the sample, chi is defined as the angle such that the normal of the planes is rotating 

radially about the x-ray beam. The sample was mounted such that if the liquid 

crystals aligned themselves to one of the glass slides, one would expect to see a signal 

at either x=90° or 180". As one would expect, the competition between the surface 

forces of the two pieces of glass should cause the liquid crystals to align themselves 

somewhere in between these two values. The figure below shows two runs; one with 

parallel alignment (solid line) and one with perpendicular alignment (dotted line). 

The parallel glass was prepared such that a peak would be seen at either x=OO or 

180" and indeed, we saw a peak centered at 180". The perpendicular glass showed 

multiple peaks centered at 115". Clearly, there is a competition between the walls 

which causes the liquid crystals to settle between 90" and 180". The multiple peaks 

show that the liquid crystals have not formed into nicely formed layers that stretch 

from wall to wall. Most likely, the liquid crystals closest to each wall are turned 

slightly in the direction of the orientiation of the glass. 

More complete analysis will give analytical values to the shape of these curves, 

especially the perpendicular sample where there is, clearly, at least three peaks. 

Figure 1. This shows two different scans; one with the glass aligned parallel and 

one perpendicular. The liquid crystals align nicely with the parallel alignment, but 

experience a competition between the surfaces of the perpendicular alignment. 

P w * Work supported by the American Chemical Society Petroleum Research Fund under 

01 

w grant No 31097-AC5 and U.S. DOE Grant No. DE-FG02-85ER45183 

Long-Range Order and Critical Diffuse Scattering from the Tricrit- 1 X18A 1 

ical System V-H near the PI-Pz-Phase Transition * 

J. Trenkler, P. Chow, U. Klemradt, S. C. Moss (U. of Houston), D. Lott (BNL- 

NSLS), S. Ehrlich (Purdue U.), R. Hempelmann (U. des Saarlandes) 

The tricritical behavior of a single domain single crystal of VH0.525 and VH0.547 

has been studied by x-ray scattering. We first measured the tricritical order pa- 

rameter exponent p of VH0.547 by the temperature dependence of the integrated 

Bragg-intensity of superstructure reflections below the critical temperature Tc. We 

found that VH0.547 passes a large two-phase coexistence region deduced from the 

appearance of a second fundamental reflection in the radial intensity distribution 

around the fundamental reflection (0 3 3) associated with the /32-high temperature 

phase. The existence of the two-phase region is also shown by a sudden drop in 

the integrated intensity of superstructure reflections as shown in fig. 1. Above the 

critical temperature, weak critical diffuse scattering (CDS) was measured indicating 

that the data is taken in the vicinity of a tricritical point. 

With another single domain single crystal, VH0.525, we recently observed a re- 

markable change in the intensity line shape of the critical diffuse scattering in the 

longitudinal [0 1 1 scan at T=Tc+6.2 K in an experiment done at the NSLS on 

X14A. At X18A, the Q- and temperature dependence of this profile was investi- 

gated at Q=10.64 l/A with AQ=0.14 1IA between T=Tc+4 K and T=Tc+9 K 

at a different penetration depth. Fig. 2 gives an example of the measured intensity 

profile consisting of a sharp and a broad component at T=Tc+6.6 K of the (0 512 

$12)-superstructure reflection. 

- L 432 434 436 438 440 442 

Temperature [K] 

Figure 1. Integrated intensities of the (0 

512 $12) and (0 712 712) superstructure 

reflections in a heating run. 

. -- 

2-0 ["I 

Figure 2. Critical diffuse scattering for 

the (0 512 $12) superstructure reflection 

in [O' 1 i] in a heating run at T=Tc+6.6 

* This work was supported by the NSF K with Tc=444.5 K. 

on DMR92-08450

7' 

w 

GI 

E3 

Preferred Orientation and Anisotropy of Piezoelectric Materials * I X18A 

Shan Wan and Keith J. Bowman (Purdue University) 

Piezoelectric materials rely upon development of preferred orientation from the 

alignment of domains during poling. The poling effect can be eliminated by thermal 

treatments. Small differences in the relevant (200) and (002) peaks, fine domain 

structures and modest degrees of orientation in tetragonal piezoelectric materi- 

als make four-circle measurements of texture on a conventional diffractometer of 

only marginal value. In this investigation the preferred orientation of poled ancl 

thermally-depoled Navy-I1 ancl Navy-VI PZT focusing on (002)/(200) peaks was 

measured. The longer x-ray wavelength, highly collimatecl source and the high 

intensity of synchrotron light enabled reliable measurements of domain orientation. 

* This work is supported by U.S. Department of Energy Grant No. DE-FG02- 

8.SER4.5183. 

Structural Evolution of Li,hInzO4 in Lithium ion Battery Cells idea- 

sured In situ Using Synchrotron X-ray Diffraction Techniques* 

X. Q. Yang, S. Mukerjee, X. Sun and J. IbIcBreen (BNL) 

I X18A I 

With the increased demand for portable devices the commercial and strategic 

requirements for higher energy efficient batteries are paramount. Among such 

promising technologies are the lithium ion rocking chair type rechargeable cells. 

However, cost, cycle life and safety consideratio~ls remain a matter of technical concern 

and need to be addressed based on specific components used. Our interest in 

the LiZh1n2O4 cathode material stems from the promise of lower cost (replacement 

of the currently used LiCo02) material, however the cycle life characteristics remain 

irreprotlucible, showing great sensitivity to preparation conclitions. Our studies on 

the structural ancl electronic (analogous XAS studies) evolution in these material 

during intercalation of lithium are aimed at providing answers to these important 

structure property relationships. 

Recent stutlies on Li,hlnzO4 prepared at different temperature and annealing 

conditions have revealed differences in their performance. nevertheless, the conventional 

x-ray diffraction could not clistingiush any differences in the initial structural 

characteristics. The Li solid state N.;\I.R studies however revealed differences in 

lithium site occupancies in samples prepared at different temperatures. The it/ in 

situ studies on the structural evolution in these material were carried out in the 

transmission mode at X18A. The preliminary results indicate that both the high 

(850°C) and low temperature (650JC) show coexistence of two cubic phases when 

x=0.5 in Li,hInaO.t. These phases however coalesce into a single cubic phase at 

the end of charge and discharge. As evident from figure I. which tiescribes the 

structural evolution in a sample prepared at G50°C ar~l annealed for 48 hours, the 

transition from one phase to the other is not smooth and their is evidence of resitlua1 

lithium remaining after the transition. Example of this behavior is shown in 

figure 1. Further studies are planned to correlate the effects of other preparation 

conclitions in the strl~tural evolution of th~se spinel mat~rial. * [\Vork supported by 

U. S. DOE contract No. DE-i\C02-7GCH00016.]

I Anomalous Transmission of X-Rays in a Quasicrystal * I X18A I 

-- 

Y. Zhang, S. N. Ehrlich and R. Colella (Purdue U.) 

Anomalous Transmission (AT) of x-rays in a quasicrystal was observed for the 

first time by S.W. Kycia et al. [I]. It is a surprising result, because the absence 

of periodicity would seem to prevent the conditions needed for the onset of AT. 

In this work we have determined the absolute value of the AT iffracted beam in a 

perfect Al71.0 Pd20.5 Mn8.5 quasicrystal, and compared with the theory. The crystal 

was 0.385 mm thick and the x-ray energy was 9.0 KeV The normal attenuation 

factor for a beam incident perpendicularly to the surface is about 1.7 x lop9. The 

incident beam intensity, at beamline X18A, was evaluated by measuring the (222) 

reflection with a perfect germanium crystal. The (222) reflection is very weak - 

it is a forbidden reflection - and its structure factor is well known because it has 

been measured by several people. The absolute value of the integrated intensity for 

the (6 4 0 0 4 6) reflection was compared with the value calculated from dynamical 

theory and found at least one order of magnitude below the theoretical value. Work 

is in progress to explain the possible reasons for such a discrepancy. 

[l] S.W. Kycia, A. I. Goldman, T. A. Lograsso, D. W. Delaney, D. Black, M. 

Sutton, E. Dufresne, R. Bruning and B. Rodricks, Phys. Rev. B 48, 3544 (1993). 

* This work is supported by U.S. Department of Energy Grant No. 

85ER45183. 

I Debve-Waller Factors in a Quasicrystal * I X18A I 

Y. Zhang, J. Sutter, S. N. Ehrlich and R. Colella (Purdue U.) 

The mean square vibrational amplitude < u2> for two reflections located on a 

twofold axis of an icosahedral quasicrystal A171.0Pd20.5Mns.~ have been determined 

between room temperature (RT) and 20 K. The Q values for the two reflections 

(= 2 sinB/X) are: Q1=1.278 k1 and Q2=2.068 ifp1. The integrated intensities 

of the two reflections were measured as a function of temperature, using the Bragg 

case of diffraction, on a large polished quasicrystalline slab. The logarithm of the 

integrated intensity is linear, proportional to temperature, near and below RT, and 

tends to saturate to a constant value at low temperatures, an effect of the zero 

point energy. It is assumed that < U2> is contributed mostly by low frequency 

acoustic modes, for which the atoms of Al, Pd and Mn vibrate together. Figures 

1 and 2 show that, indeed, < u2> is linear with temperature for both reflections 

above 100 K, but at low temperatures both plots depart significantly from Debye 

theory. In one case < u2> is greater than the theoretical value, in the other case 

it is smaller. This behavior is reminiscent of that of layered crystals (1) such as 

graphite or TaS2, in which the experimental values of are always smaller than 

those predicted by Debye theory. In the case of layered crystals the anomaly was 

explained by considering the effect of reduced dimensionality and anisotropy. The 

same arguments cannot be applied to an icosahedral quasicrystal such as Al-Pd-Mn, 

supposed to be perfectly isotropic. Work is in progress to measure other reflections, 

and to understand the physical origin of non-Debye behavior in a quasicrystal. 

[I] S.M. Hsieh and R. Colella, Solid State Commun., 63, 47-50 (1987). 

-. 

Figure 1. 

DE-FGOZ- * This work is supported by U.S. DOE 

Grant No. DE-FG02-85ER45183. 

Figure 2.

!' 

F 

m X-ray Absorption Study of Nickel in FCC Catalysts 

X18B I Characterization of a Si(Li) Detector for the SIXA Array 4 I X18B I 

S. R. Bare, A. Z. Rinwelski, F. S. Modica (UOP LLC) 

Fluid catalytic cracking (FCC) is a process for the conversion of higher molecular 

weight hydrocarbons into lighter, more-valuable products through contact with a 

powdered catalyst at the appropriate process conditions. The reactions are rapid: 

only a few seconds of contact time is necessary. Simultaneously with the desired 

reactions, coke is accumulated on the catalyst surface. This coke is combusted 

to rejuvenate the catalyst. However, cracking of heavy hydrocarbons leads to a 

problem: the high metal content, mainly nickel and vanadium, of these fractions 

accumulate on the catalyst with time. Nickel is a catalyst for dehydrogenation 

reactions, which lead to an increase in coke and hydrogen yields. UOP has used in 

situ XANES at the Ni K-edge to study the reducibility of Ni in a series of commercial 

equilibrium FCC catalysts that are heavily contaminated with Ni. Figure 1 shows 

the Ni K-edge XANES of a commercial REY equilibrium catalysts following in situ 

reduction in hydrogen at 700°C for 0 min. (as received), 3 min., 15 min., and 

45 rnin. The results indicate that Ni is reducible under these conditions. The Ni 

K-edge XANES spectrum of the as-received material is similar to that of a nickel 

aluminate, whereas there are dramatic changes in the in situ reduced spectra which 

are a cornbination of Ni metal and Ni al~uninatc. The authors have studied REY 

equilibrium catalysts with varying Ni loatling ant1 different reduction ternperatwes 

in atltlitiori to reduction times. These st~~dies illustrate that XANES is a. powerful 

tool for following the in situ oxidation states of Ni in FCC catalysts. 

0 20 40 60 80 1W 

Photon Energy IE-E ,I eV 

Figure 1. Xi K-edge X-AXES of a commercial equilibrium FCC catalyst. 

T. Tikkanen, K. Hamalainen, and S. Huotari (U. of Helsinki, Finland) 

We have studied the X-ray response of a Si(Li) detector element for the SIXA 

spectrometer array which is a focal plane detector for the SODART X-ray telescope 

onboard the Spectrum-X-Gamma satellite. Energy spectra were recorded using 

monochromatized synchrotron radiation ranging from 7 to 21 keV, yielding the 

detector lineshapes for the upper part of the detector's energy range (0.5-20 keV). 

Special attention was paid to the photon energy region above the Lg absorption 

edge of gold, because the cathode electrodes of the Si(Li) elements are formed 

by gold-palladium alloy contact layers and the equivalent thickness of gold can 

be rneasurecl by observing the characteristic L-shell X-rays of gold excited by the 

primary radiation. The results obtained at 4 different photon energies below the 

La edge yield an average value of 22.4 f 3.5 nnl which is consistent with the earlier 

result extracted from detection efficiency measurements.

I Bond-length Distortions in Strained-semiconductor Alloys X18B 

J.C. Woicik, J.G. Pellegrino, and B. Steiner (NIST) K.E. Miyano (Brooklyn U.) 

S.G. Bompadre and L.B. Sorensen (Washington U.) T.-L. Lee (Northwestern U.) 

S. Khalid (NSLS) 

Extended x-ray absorption fine structure performed at the In-K edge has resolved 

the outstanding issue of bond-length strain in semiconductor-alloy heterostruc- 

tures. We determine the In-As bond length in a buried 213 A Gao.wIno.22As layer 

grown coherently on GaAs(001) to be 2.581 +/- 0.004 A. This bond length corre- 

sponds to a strain- induced contraction of 0.015 +/- 0.004 A relative to the In-As 

bond length in bulk Gal-xInxAs of the same composition; it is consistent with a 

simple model which assumes a uniform bond-length distortion in the epilayer despite 

the different In-As and Ga-As bond lengths. 

I XANES Analysis of Ti-V-Silicalites I X19A I 

S. R. Bare, A. Z. Ringwelski, F. S. Modica, L. Nemeth (UOP LLC) 

The partial oxidation of propylene to propylene oxide is an important indus- 

trial process. Currently, no direct synthesis route to propylene oxide is practiced 

commercially. The isomorpbous framework titanium-substituted silicalite (MFI) 

has been shown to be selective for the epoxidation reaction which uses hydrogen 

peroxide as an environmentally clean oxidant. Research at UOP has focused on 

synthesizing a more-active epoxidation catalyst with the MFI structure, which con- 

tains both Ti and V. These catalysts exhibit an excellent yield of propylene oxide 

using hydrogen peroxide as the oxidant. UOP has used XANES at the Ti and V 

K-edges to characterize these materials. Figure 1 shows the Ti K-edge XANES 

of several reference materials and two Ti-V-silicalite catalysts. The spectra of the 

catalysts are consistent with all of the Ti being in the MFI framework. Figure 2 

shows the V K-edge XANES of two V-silicalite catalysts and several V-containing 

reference materials with different V oxidation state and symmetry. These data, 

which are being used to guide the synthesis program, indicate that the V is present 

in oxidation state +5 and is four fold coordinated. 

0 20 40 50 80 100 120 141) 

Photon Energy (E-E ,) ev 

P 

0 20 10 60 80 100 120 110 

Photon Energy iE E .I eY 

Figure 1. Ti K-edge XANES of Ti-V- Figure 2. V K-edge XANES of V- 

silicaltes and reference materials. silicalites and reference materials.

F 1 

/ X-ray Absorption Spectroscopy of Cesium Modified Catalysts 

U1 

c, E.J. Doskocil and R.J. Davis (U. of Virginia) 

Xl9A 

Alkali modified zeolites are materials useful in heterogeneous catalysis in which 

base strength increases with increasing electropositivity of the alkali cation. Addition 

of occluded alkali has been found to further increase the surface basicity. Being 

able to understand how Cs, the most electropositive alkali, interacts with the zeolite 

framework on a molecular level would aid in understanding how cesium influences 

the basic character of the zeolite. IVe have therefore used XXS at the cesium L edges 

to probe the local environment of cesium for a variety of Cs modified catalysts. 

The Cs Lrrr edge occurred within f-0.5 eV for each compound and catalyst studied, 

indicating an electronic state of Cs" for these materials. As seen in Figure 1, 

the white line intensity for the cesium form of zeolite X exhibits a higher white line 

intensity than each of the Cs compounds studied. This inclicates a larger density 

of unoccupied 5d states for cesium present in supported samples than in bulk cornpounds, 

showing that cesium behaves more like a free-ion in the cesium modified 

catalysts. 

Figure 2 shows the EXAFS spectra for a few of the cesium compounds and catalysts, 

which is complicated by the presence of a double excitation peak about 100 

eV above the edge. The con~pountls have similar EXAFS spectra. The zeolit,ic 

materials contain an atltlitional oscillation in their spectra before the double excitation 

which is not observetl for the cornpounds stutlietl. The cesium modified 

carbon catalyst shows an EXAES spectrurn in which the frequency is less than that 

observed for the zeolite cases, indicating - a srnallrr interatomic distance for cesium 

in thc micropores of carbon thu~ for cesiwn in the zeolite cages. 

-15 0 15 30 45 

Encrgy i cV 

Figure 1. XXSES of Cs/KX. Cs20 and Figure 2. EX-IFS of various Cs catalysts 

Cs2CO3. and compounds. 

XANES Characterization of Soil Phosphorus I X19A 

D. Hesterberg, W. Zhou, S. Beauchemin*, and D. E. Sayers (NC State and *Ag- 

Canada) 

Excessive levels of soil phosphorus derived from animal waste applications to agri- 

cultural soils are of concern because P discharged from these soils may deteriorate 

surface water quality. Soils typically have a limited capacity to bind phosphate by 

surface adsorption. However, thermodynamics predicts that the solubility of solid- 

phase precipitates is independent of the amount of the precipitate present. Thus, 

the formation of precipitates such as Ca-, Al-, or Fe-phosphates in soils may serve 

as a sink for high levels of added P. The objective of this study is to determine 

whether precipitates of Ca-phosphate (at pH i7) or Fe- or Al-phosphates (at pH i7) 

occur in soils containing high levels of phosphorus. Pairs of soil sarnples collected 

from different regions of Quebec and having similar total P concentrations (29 to 

72 ~nrnol P/kg) but different pH levels were analyzed at the P K-edge at Beamline 

XlSA, along with synthetic Ca-, Fe-, and Al-phosphates anti other stantlards. Phos- 

phorus K-XANES spectra in Fig. 1 show that each of the three nlineral stantlards 

have distinguishing spectral features. such as a pre-edge feature on the strengite 

(FeP042H20) spectrum and a shoulder on the high-energy side of the white-line 

peak in the amorphous Ca-phosphate spectrum. Soil spectra indicated differences 

in the average local molecular bonding of phosphorus (Fig. I). For example, the 

soil having pH 7.6 (43 mrriol P/kg) has a broad shoulder on the white-line peak 

that rnay be indicative of Ca-phosphate. This feature is not evident in the spec- 

trutrl frotn the soil of pH 6.3 (42 mmol/kg). The soil spectra probably rasult from 

multiple P phases that might be resolved by additional XANES analyses coupled 

with soil fractionation procedures designed to concentmtc different phasrs. 

Figure 1. Sormalized P K-XIYES spectra of samples from the -I horizon of soils 

along with standards of phosphate mineral phases.

P 

V1 

In Situ Characterization of the Reduction of Rh / CexZrl-xOz * I X19A / 

S.H. Overbury, D.R. Huntley, D.R. Mullins (ORNL) and G. Glavee (Lawrence U.) 

In automotive catalysts, ceria is used as an oxygen storagelrelease media to aid 

in maintaining high conversions during oscillations in airlfuel ratio. Recently, it has 

been reported that doping Zr into the ceria enhances the oxygen storage capacity 

of the oxide [I]. We have measured this enhancement by in situ XANES and find 

that the presence of Rh further enhances reducibility. 

High surface area (Cel-,Zr,)Oz where x=0.0-0.5 were prepared by sol-gel techniques 

and hypercritical drying. Portions of the samples were impregnated with 

Rh(N03)3. After calcining in air at 800 K, the catalysts had surface areas in excess 

of 100m~/~. Samples were suspended in an alcoholic solution and dispersed on the 

surface of BN pellets. The pellets were placed in a quartz tube reactor under flowing 

He, hydrogen or air. X-ray absorption at the Ce LII~ edge was used in transmission 

mode to distinguish the presence of Cef3 and Cef4. 

Figure la shows typical Ce LIII edge x-ray absorption spectra of one of the 

samples as its temperature is increased in H2/He. Various changes indicative of 

reduction from Cef4. to Ce+3 are observed including a decrease in the intensity 

of the peak labeled C. The intensity of this peak above background is indicative 

of the extent of reduction of the samples. Results are shown in Figure 1b for 

three different catalysts vs reduction temperature. It is seen that adding Zr to the 

CeO2 decreases the temperature required for reduction and increases the extent of 

achievable reduction. Addition of Rh further catalyzes the reduction process. 

[I] P. Fornasiero et al., J. Catal. 164 (1996),173. 

5700 5750 5800 


0.0 

Degree of reduction 

Figure 1. A) Ce LI~I XAS spectra recorded during the reduction of (Ce0.7Zr0.3)02. 

B) The degree of reduction vs temperature for several ceria based catalysts. 

* Research sponsored by U. S. Department of Energy, Division of Chemical Sciences, 

Office of Basic Energy Sciences, under contract number DE-AC05-960R22464 with Oak 

Ridge National Laboratory, managed by Lockheed Martin Energy Research Corp. 

Observation of a Novel 4-Layer Superlattice in a Smectic Liquid 

Crystal Using Anomalous Diffraction 

I X1SA I 

R. Pindak (Bell Labs), A.M. Levelut (Orsay), P. Barois (CRPP), P. Mach (Univ. 

of Minnesota), and L. Furenlid (NSLS) 

Classical x-ray diffraction experiments cannot distinguish between variants of 

the chiral Smectic-C (SmC*) liquid crystal phases since the tilted molecules in the 

fluid layers of these variants have identical projected electron density profiles with 

only the tilt direction changing between layers. Nonetheless, by working close to 

an absorption edge, classical extinction rules no longer hold and it is possible to 

distinguish between the variants. 

To test this hypothesis, we studied the n=ll (C11) member of a sulfur containing 

thiobenzoate liquid crystal. In bulk samples, C11 exhibits the whole sequence of 

SmC* variants. A 200 layer freely suspended film of CII was prepared in situ in an 

oven mounted on a two circle diffractometer. Measurements were performed at the 

maximum of the sulfur absorption peak (Eo). Above 103 degC, in a qz-scan where 

z is normal to the layers, two diffraction peaks were observed corresponding to the 

first and second order reflection from the layer planes (qz = qo and 2 qo). At lower 

temperatures down to crystallization at 90 degC, additional sharp and resolution 

limited peaks were seen at qz = 0.5 , 0.75 , 1.25 , 1.5 , 1.75 , and 2.25 qo. Fig.2 

shows, for the 1.75 qo peak, that the intensity of the satellite peaks decreased as 

the energy was moved more than 7eV from Eo. The diffraction spectrum observed 

between 90 and 103 degC is characteristic of a four layer superlattice with a 41 or 

43 symmetry. We propose that this novel superlattice has the following structure 

shown in Fig.1: in each layer, the molecules are tilted at the same angle with 

respect to the layer normal but the projection of the molecules forms a helical array 

of four layers pitch. In conclusion, we unambiguously demonstrated that anomalous 

scattering can distinguish the SmC* variants as well as observed the occurrence of 

a novel fourfold helical symmetry. 

Figure 1. 

5 

.$ 

g 4 

m 

3 

3 

2 

Figure 2. 

E-EO (eV) 

5

+ 

G7 

(10 I 

Characterization of Sulfur Oxidation States in Soil Humic Acid I X19A I 

W. Zhou, D. Hesterberg, K. Hutchison, and D. E. Sayers (NC State) 

Past research indicates that sequestering of heavy metal contaminants by reduced 

forms of sulfur, especially inorganic sulfides, reduces the toxicity of metals in aquatic 

sediments. The role of metal sulfur bonding to both inorganic and organic sulfur 

forms in soils is not well understood, but could impact the chemistry of heavy 

metals in contaminated soils. The objective of this study was to determine whether 

chalcophilic metals preferentially bind to organic sulfur functional groups in soil 

organic matter. Sulfur-rich humic acid (HA) was extracted from soil from a coastal 

marine wetland antl reacted in aqueous solution with Cu(I1) or Hg(1I) at pH 5.6. 

The molar ratio of organic S to metal was 4.25, and the total sulfur concentration 

in the suspensions was 8.5 mmol/kg. Sulfur K-XANES analyses clone at Beamline 

X-19A was used to determine sulfur oxidation states. Initial data showed that 

organic sulfnr in the original, freeze-clriecl HA sample and in the aqueons metal-HA 

suspensions was in a highly oxidized form (Fig. I - HA Batch 1). Because metalsulfur 

binding should occur at reduced sulfur groups, such bonding is ~mlikely in 

this system. Sulfur oxidation mas considered to be an artifact of highly alkaline 

or acidic conditions occurring during certaiu steps of the HA extraction proccthire. 

Therefore, a second batch of HA was extracted using a more restricted pH range. 

Sulfur K-XANES resl~lts from this batch indicated that about half of the orgartic 

sulfur in the original HA and the aqueous suspensions was in a reduced oxidation 

state (Fig. 1). The S K-XANES results will conlplenlent EXAFS analyses at 

Bramline X-11.4 aimed at tleterrnining the rnolecttlar-bontli~~g cnvironuicrlt of the 

metals. 

1 

2 240. 

3 3" 

HA Batch 2 

HA Batch 1 

, , 

, 

Figure 1. Normalized sulfur K-XANES spectra of aqueous samples of Cu reacted 

with soil humic acid (H.1) from two different extractions: most of the organic S in 

Batch 1 was oxidized during extraction. 

X-Ray Reflectivity of Polymeric Surfactants at the Air-Water Inter- / X19C I 

face. 

A. S. Brown (Australian National U.), S. A. Holt (U. of New South Wales) and G. 

J. Foran (Australian National Beamline Facility) 

At the time these experiments were undertaken our research group was in the 

process of commissioning a new x-ray reflectometer at the Research School of Chem- 

istry, and were taking the first reliable data using the instrument. Software had 

been developed in-house for the simultaneous refinement of models against both 

x-ray and neutron data, from both energy- and angle-dispersive instruments, with 

or without constraints, but had not yet been proven for use with x-ray data. For 

this reason we measured x-ray reflectivity data for two simple air-liquid interfaces 

at beamline X19C using the liquid surface spectrometer, for benchmarking our own 

reflectometer and for testing the software. The tlata we collectetl for air-water and 

air-hexatlecane interfaces vieltled interface rougln~esses which agreed well with lit- 

erature values (2.7 + 0.1 i\ for air-water antl 3.9 + 0.3 a for air-hexadecane). Data 

subsequently acquired with our in-house reflectometer for these two systems also 

agreed well with the literature, antl confirnled for us that both our reflectometer 

autl software were performing correctly. 

Data were also collected for rrtonolayer films of an end-functionaliscd polystyrene 

surfactant spread at the air-water interface, cornpressed to s11rface pressures of 0.5, 

2.0 and 6.0 m~m-l. These data were collected to provide an atltlitional coutrast 

to complement several nelitron tlata sets we have for this material. Tttc neutron 

tlata alone are not sufficient to resolve the film structure unambiguously. The x-ray 

tlata have provirled significaut atltlitional iuforrnatiou which is cl~rrcntly beiug used 

in resolving the film structllres by refinement of models against both x-ray and 

rlentron tlata simdtaneously.

P P 

U1 

Combined SWBXT and HRTXD Studies on Defect Distributions in 

11-VI Compound Semiconductors I. CdZnTe * 

X19C 

Y. Guo, H. Chung, J. Su, M. Dudley (SUNY at Stony Brook), H. M. Volz, C. 

Salles, and R. J. Matyi (U. of Wisonsin-Madison) 

Wafers sliced from the microgravity-grown CdZnTe boules (GCRC-1 & GCRC- 

2) were imaged by SWBXT. Figure l(a) shows a transmission topograph recorded 

from a wafer cut from the region of boule GCRC-2 with the best quality. Individual 

dislocations (D) are clearly resolved. A dislocation density of the order of 5 X 10' to 

1.2 X lo3 cm-2 is estimated. Note that the dislocations are distributed uniformly 

and no subgrain structure is observed. Other defects characterized are a few Te 

precipitates (P). Formation of these precipitates can be attributed to the retrograde 

solubililty of Te in CdZnTe. Figure l(b) illustrates the diffracted intensity about the 

333 reciprocal lattice point from a similar CdZnTe wafer to the one shown in Figure 

l(a). The figure represents a "map" of the distribution of the diffracted intensity 

in reciprocal space. The presence of a well-defined surface streak is indicative of 

two qualities of the diffracting crystal: (1) the bulk crystal has sufficient structural 

perfection in order to diffract dynamically, and (2) the crystal surface is of high 

enough quality to produce the surface streak. SWBXT and HRTXD results match 

very well. 

Figure 1. (a)Transmission x-ray topograph (g=113, ~=0.42A) recorded from a wafer 

sliced from the most slowly cooled region of GCRC-2. Individual dislocations (D) 

and precipitates (P) are clearly observed; (b) Triple crystal diffraction scan about 

the 333 reciprocal lattice point from a similar sample. 

* Work performed on the Stony Brook Synchrotron Topography Beamline X-19C and 

W supported by NASA Marshall Space Flight Center 

Combined SWBXT and HRTXD Studies on Defect Distributions in 

11-VI Compound Semiconductors I1 ZnSe 

Y. Guo, H. Chung, J. Su, M. Dudley (SUNY at Stony Brook), H. M. Volz, C. 

Salles, and R. J. Matyi (U. of Wisconsin-Madison) 

In ZnSe, an even distribution of dislocations was revealed by SWBXT, with no 

cellular structure being discernible. An example of a topograph recorded from this 

polished sample, revealing this microstructure is shown in Figure l(a). Additionally, 

a few slip bands (S) are also observed. Figure l(b) is a 220 reciprocal space map from 

a similar ZnSe sample. The absence of any surface streak and both the intensity 

and the angular extent of the diffuse intensity is indicative of a highly defective 

surface region in this sample. This interpretation agrees with SWBXT. 

Figure 2(a) shows a reflection topograph recorded from a ZnSe sample with a 

cleaved (rather than a polished) (110) surface shows a high density of uniformly 

distributed dislocations and twins. Likewise, HRTXD showed a well-defined sur- 

face streak and a large amount of diffuse scatter that was distributed perpendicular 

to the [110] surface normal direction indicative of a high dislocation density. The 

uniformity of the diffuse intensity suggested that the dislocations are randomly 

distributed throughout the crystal and not concentrated in the form of subgrain 

boundaries. Comparison between the polished and cleaved samples seems to indi- 

cate that polishing damage can obscure the true as-grown microstructure in ZnSe. 

Figure 1. Figure 2.

F 

Characterization of Defects in Sic Devices Using Synchrotron White 

Beam X-ray Topography and Their Relationship with Device Per- X19C 

formance 

TIT. Huang, hI. Dudley (SUNY Stony Brook). P. Neudeck (NASA Lewis Research 

Center): C. Fazi (Army Research Lab.) 

Crystallographic defects such as dislocations in semiconductor crystals can have 

detrimental effects on the performance of devices. Synchrotron White Beam X-ray 

Topography (SWBXT) have been used to characterize the defect structures in Sic 

crystals of various polytype and to determine how these defect structures can influence 

the performar~ce of various kinds of device rna~lufactl~recl therefrom.Figure 1 is 

a back-reflection topograph shows the defect structures in a SIC crystal. The device 

topology can he tliscernetl due to the finite absorption of the metallization layer as 

well as due to contrast associated with the strain discontinuities at the edges of the 

metallization layer. Electrical perforn~ance of such devices were tested. A I-V curve 

is shown in figure 2. Correlation with tlefect map antl tlevice performance reveal the 

detailed influence of the defects present in the crystal on the tlevice perforrnance. 

Rcsult,s show that high density and large Burgers vector dislocations tlccrease a d 

reversc breakdown voltage antl ir~crease t,he Irakagc cwrent. XIicroplasma associated 

with swfacc morphology and rr~icropipes was ot~scrvetl when voltagc is applied. 

Figure 1. Topograph recorded from a 

6H-SIC crystal with del-ices fabricated 

upon it. S indicates large Burgers vec- 

tor screw dislocation (micropipe). E in- 

dicates eletrocle. 

Figure 2. A room-temperature 1-1- char- 

acteristics of a SiC diode. 

Contrast Mechanism of Super Screw Dislocations in Back-reflection 

Synchrotron Topographs * 

X19C 

X. R. Huang, hI. Dudley (SUNY at Stony Brook), C. H. Carter: Jr. (Cree Research. 

Inc) 

As a powerful and efficient diffraction imaging technique for studying crystal 

defects. sy~lchrotron white-beam x-ray topography (Sn7BXT) has been investigated 

extensively in the transmission geometry, but the back-reflection case was sclclom 

used and the corresponding principles and mechanisms of contrast formation are 

not fully unclerstootl. In our systematic experiments, however, it was found that 

the back-reflection SWBXT (with Bragg angle around 80") is a particularly useful 

tool for observation of super screw tlislocations (SSDs) in Sic, a wide-bandgap. 

high-ten~perature semicontl~~ctor material. The typical topographic cor~trast of an 

individual SSD perpendicular to a (0001) GH-Sic wafer surface is shown in Fig. l(a), 

where the clislocation image is a black ring encircling a white centrr. Besides the 

cxpcrinlental observation. a new general program based on the ray-tracing principles 

was established to simulate the dislocation contrast ir~ back-reflection topographs. 

The sirm~latecl image of a SSD, as plottrd in Fig. l(b). coincides exactly with 

the recortletl image both in tlirrierlsion antl in intensity distribution. hloreovrr, 

the sirru~lation drmonstratctl clearly the strair~ field of screw tlislocatior~s as n ~ll 

as the kinematic cliffrnctior~ behavior of the deformed lattice. From the simulation, 

the tleprnrlency of the dislocation image size on the magnitude of the Burgcrs 

vcctor was obtainrtl, which provides a dircct criterion for qllantitative analysis of 

SSDs. Grxzing-rctlcction topography and the corresponding simulation were also 

performed to reveal the surface relaxation of SSDs. The tlrtailetl cont,rast rnrrharlisrns 

of bark-rdcction S\\'BXT lvcrc, thlls, ol,t,ainetl fro111 the cxperirnents 

Figure 1. Recorded (a) and simulated (b) images of a SSD (Burgers vector b = 8c) 

in 00024 back-reflection topographs (Bragg angle / 3~ = 81.4'). Sote that the black 

streaks in (a) correspond to contrast of basal-plane dislocations. 

IYork performed on the Synchrotron Topography Project. Beamline S-19C. and sup- 

ported by =\RP.I '.IFIVL under Grant So. FYI-1.57-9.7-03103.

td 

F 

Determination of Super Screw Dislocation Sense with Synchrotron 

Back-reflection Section Topography * 

X. R. Huang, M. Dudley, W. M. Vetter (SUNY at Stony Brook), R. Glass, V. 

Tsvetkov, and C. Carter, Jr. (Cree Research, Inc.) 

Synchrotron radiation topography has been widely applied to observe dislocations 

in single crystals and epitaxial heterostructures. Although the criterion g.b = 0 can 

be used to analyze dislocation Burgers vectors, it is still hard to distinguish two dislocations 

with antiparallel Burgers vectors (opposite senses) from their topographic 

contrast. In the investigations of super screw dislocations (SSDs) in Sic, we designed 

a novel technique, namely white-beam back-reflection section topography 

(WBBRST) which can show clearly the sense of an individual SSD. 

In our experiments, the incident synchrotron beam was limited to be 15 pm in 

width by a slit and was carefully adjusted to cover the core region of a specific 

SSD for the 00024 back reflection. The topographic contrast of a SSD in a (0001) 

6H-Sic wafer is shown in Fig.l(a), in which the dislocation image splits into two 

disconnected "tails" near the image center. Figure l(b) represents the simulated 

image which was calculated on the basis of the strain field of a right-handed SSD. 

These two patterns indicate that, in addition to the radial shift, the diffracted x 

rays are twisted around the principle diffraction direction with left-handed screw 

- ,,, 

direction. For a left-handed SSD as shown in Fig. lfc). the twist of the x raw is 

naturally right-handed. 

Besides the application of dislocation-sense determination, WBBRST can also be 

used to analyze the local strain field of other crystal defects and is of great help for 

understanding the contrast mechanisms of back-reflection topography. 

Figure 1. Back-reflection section topographs showing the senses of SSDs in 6H-Sic. 

(a) and (b) are the recorded and simulated images of a right-handed DDS while (c) 

corresponds to a left-handed DDS. The curved arrow indicates the twisting direction 

of the diffracted x rays. 

m 

* Work performed on the Synchrotron Topography Project, Bearnline X-19C, and supr 

ported by ARPAIAFWL under Grand No. FY1457-95-03108. 

The Liquid-vapor Interface Structure of Tin:Gallium 1 X19C 

Ning Lei and Stuart A. Rice (U. of Chicago) 

The liquid-vapor interface structure of a tin:gallium alloy has been studied by 

x-ray specular reflectivity and grazing incidence in-plane x-ray diffraction. The 

reflectivity data are consistent with a model of stratified layers of atoms at the 

interface, with 100% tin coverage for the outermost layer and -22% tin in the second 

outermost layer. In- plane diffraction data reveal that the tin atoms in the interface 

are in liquid state. Reflectivity and in-plane data show independently that the 

diameter of the tin atoms in the interface is about 5% smaller than that in its pure 

3-d liquid state at the temperature around 40°Celsius. The alloy surface tensions 

at four different temperatures are deduced from the sample shape measured by x- 

ray reflection of the sample. The surface tensions measured show clearly that with 

increasing sample temperature, the surface tension increases. We explain this to be 

due to the increased solubility of tin in the bulk at a higher temperature and less tin 

at the interface as shown by the reflectivity data. The tin atom enthaphy difference 

between that at the interface and that in the bulk is shown to be proportional to 

the temperature derivative of the surface tension; and thus the enthaphy at the 

interface is of a smaller value.

P 1 Gold Colloid Nano-Structures in Polymer Thin Films 

I X19C 

F 

m 

CJ B. Lin, M. Meron, and P.J. Viccaro (CARS-U. Chicago), S. Williams and LI. L. 

Schlossman (Physics-UIC), T. RIorkved, H. Jaeger, and Z. Huang(JF1-U. Chicago) 

Materials structured on the nanometer length scale promise to be the next generation 

of materials for electronics. It may be possible to use the nanometer length 

scale structures that spontaneously self-assemble in complex fluids as templates 

to form these nan+structured electronics materials. This methodology has been 

pursued by Terry hlorkvecl, a graduate student in Heinrich Jaeger's group at. the 

University of Chicago. in preparing a nano-structured system in which gold metal is 

deposited on and then annealed into a polymer thin film (-50nm thick). Transmission 

electron microscopy by hlorkved revealed that the gold metal is self- assembled 

and ordered in-plane into spheres or rods of nanometer dimensions inside the polyrner 

films. However. electron microscopy was unable to atldress the important issue 

of the distribution of the gold spheres along the normal of the polymer films. 

By nsing x-ray specular reflectivity (not shown) accompanied by x-ray reflection 

standing wave fluorescence spectroscopy. we measured the electron density antl Au 

atomic density profiles along the surfxe normal of a goltl-sphere-inlpregnatecl thin 

polymer film. This PS-b-Pl'P diblock copolymer film consists of poly vinyl pyritline 

(PVP) spheres (- 20 nrn tliarneter) embedded in a polystyrene (PS) matrix (- 

50nrn thick). Figure 1 shows x-ray reflection standing wave fl~~orescence spectrum. 

For comparison. we also performed the same rneas~~rements (shown in Fig.2) on a 

polymer film of PS hornopolvrner (- 50 nm thick); goltl atoms, amount to a laver 

of - 0.5nm, were coated on top of the polymer film and were not annealed. These 

goltl atoms were not spread on top of the polyrr~er film uniformly; instcatl, they 

balled up into - 8 nm spheres. The solid line in Fig.2 is t,hcoretical calculation for 

the spectrum using Parratt's forn~ulatiorl. 

IVhile a quantitative analysis for the distribution of the goltl spheres imbedded 

in the PS-b-PVP film has yet to be made, thr unambigl~ous qualitative results from 

both techniques int1ic;ite that the goltl spt~crcs are smeared along the normal of 

the film instcatl of being arranged within a narrow plane in the middle of the film. 

Although the gold sphrres are somewhat orclcretl into a lattice within the plane of 

the film, they are not ordered normal to the plane. 


( Effect of Constrained Growth on Defect Structures in Microgravity- 1 , , I 

A I Y U 

( Grown CdZnTe Boules I. Nucleation of Grains * 

B. Raghothamachar, - 

H. Chung, hI. Dudley, D.J. Larson Jr. (SUNY at Stony 

Brook) 

In order to study the effect of constrained growth on the defect structures in 

microgravity grown samples, a CdZnTe bode (GCRC-1) was grown in a carboncoated 

quartz ampoule by the seeded Bridgman-Stockbarger growth method under 

constrained conditions aboard NASA space shuttle flight UShIL-2. Forced wall 

contact conditions were created by utilizing PBN springs pressed against the molten 

CdZnTe at the tail end. Synchrotron white beam x-ray topography (SWBXT) was 

then used to characterize defect structures in the bode by imaging the wafers sliced 

from it. 

Figure I shows a diffraction pattern recorded from wafer # OW2 which was 

slicctl from the steady state growth region. Clearly, this is a superposition of several 

diffraction patterns from regions of different orientations present in the wafer. 

Detailed studies revealed no definite orientation relationships between the differeut 

grains. Nucleation of several grains can be explained in the following wav. During 

growth under constrained contlitions, it is observed that generally, rnaximunl stress 

concentration occurs at the ampoule wall just below the solid-liquid interface where 

heat extraction occurs. Adhesion retl~~ces the interfacial cnergv between the solid 

nuclem antl ampoule surface thus favoring the nucleation of new grains at snlaller 

~lntlcrcooling. 

Figure 1. X-ray diffraction pattern in the reflection geometry from wafer YOII-2 

showing atleast three different large grains (GI. G2. GQ) and other smaller grains. 

* IVork performed on the Ston Brook Synchrotron Topography Beamline X-1SC and 

supported by SAS.1 lkirshall Space Flight Center.

Effect of Constrained Growth on Defect Structures in Microgravity- 

Grown CdZnTe Boules 11. Inhomogeneous Strains * 

Inhomogeneous strains were observed in several regions of the boule grown under 

constrained conditions on USML-2. A reflection topograph (Fig. 1) (g = 551) taken 

from the seed transition region shows a highly distorted image indicating presence 

of heavy inhomogeneous strains. The grain grown from the seed is subjected to 

high stresses due to forced wall contact especially in the shoulder regions and this 

must have resulted in high strains. Stress models clearly show that the shouldering 

operation generated very high stresses and static friction in this region could sig- 

nificantly increase the local stresses. In the steady state growth region, a reflection 

topograph (g = 422) taken from a grain present in wafer #OW7 is shown in Fig. 

2. This topograph shows a distorted image in most regions due to the presence of 

large inhomogeneous strains. Here, the level of thermal gradient stresses generated 

by rapid cooling are expected to be much greater than the critical resolved shear 

stress of CdZnTe. However, because of the constrained conditions forced by the 

restraining springs, a hydrostatic stress state is created which prevents deformation 

by shear. Instead the stresses cause large amount of strains. 

Figure 1. 

- 

* Work performed on the Stony Brook 

Synchrotron Topography Beamline X-19C 

and supported by NASA Marshall Space 

Flight Center. 

X19C 

B. Raghothamachar, H. Chung, M. Dudley, and D.J. Larson Jr. (SUNY, Stony 

Brook) 

Figure 2. 

I Effect of Constrained Growth on Defect Structures in Microgravity- - I ,,, , 1 

" 

AlYb 

I Grown CdZnTe Boules 111. Twins * 

B. Raghothamachar, H. Chung, M. Dudley, and D.J. Larson Jr. (SUNY, Stony 

Brook) 

The high ionicity of CdZnTe makes it extremely prone to twinning. Nucleation 

of twins is generally observed to occur at regions of disturbances at the growth 

interface. Fig. 1 shows a white beam topograph (g = 004) taken in the reflection 

geometry from a grain showing a relatively good crystalline quality present in wafer 

#OW7. However, the peripheral regions are still highly strained due to effects 

related to wall contact. Additionally, this grain also shows the presence of lamellar 

twins (T) which are revealed by orientation contrast. Detailed analysis of back 

reflection Laue diffraction patterns recorded from these twinned regions reveal that 

the twins are of the 180' rotation type about the (111) plane normal. Nucleation of 

these twins appears to have occurred because of effects related to wall contact. Small 

angle grain boundaries (SB) revealed by orientation contrast are also observed in 

some regions. Their formation can be attributed to the process of polygonization 

i.e. stress-induced glide and climb of dislocations introduced in the crystal during 

solidification. This process occurs during post-solidification cooling. 

Figure 1. 

* Work performed on the Stony Brook Synchrotron Topography Beamline X-19C and 

supported by NASA Marshall Space Flight Center.

Studies on Interface Demarcation in Bridgman-Stockbarger Grown 

CdZnTe Single Crystals by SWBXT * 

B.Raghothamachar, hI. Dudley, and D.J. Larson Jr., (SUNY, Stony Brook) 

A CdZnTe bode grown by the seeded vertical Bridgman-Stockbarger method of 

crystal growth was subjected to frequent stop and start operations during the course 

of its growth in order to demarcate the growth interface. Demarcation was expected 

to be caused by changes in zinc concentration at the solid-liquid interface induced by 

the applied disturbance. Wafers sliced from this bode mere subsequently examined 

by SIVBXT. The wide spectral range of SIVBXT allows imaging of crystals with 

regions of different lattice parameter (protluced by segregation or localized strains) 

that are likely to be introduced during such stop and start operations. Studies of 

the topographs taken from thr wafers revealed no contrast variations due to change 

in conlposition. Rather it was observed that twins were nucleated at the stop and 

start locations. Fig. 1 shows a reflection topograph (g = 133) recorded from a wafer 

cut from this bode. Iri this wafer the distorted region A revealed by orientation 

contrast codtl possibly have been created by a stop and start operation. It is also 

observed that as soon as growth was rccommencetl, a twin T1 (180" rotation type 

about the (111) plane riorrnd) was nuclratetl. Lamellar twins T2 (180' rotation 

type about the (111) plane normal) are also characterized. Other defects observed 

are slip bands (S). sub grain hol~ntlarics (SB arid inrlusioris of Te (I). 

Characterization of Twinning Operations in PVT Grown CdTe Sin- 

gle Crystals by SWBXT * 

B. Raghothamachar, hI. Dudley (SUNY, Stony Brook), W. Palosz, D. C. Gillies 

(NASA Marshall Space Flight Center) 

Twinning operations in CdTe single crystals grown by the PVT technique have 

been characterized by synch_rotron white beam x-ray topography. Fig. 1 shows a 

reflection topograph (g = 511) recorded from a wafer of PVT CdTe. Two twins 

TI and Tz are identified in this topograph. Twin TI is revealed by orientation 

contrast while twin Tz is revealed by cliffraction contrast. Figures 2(a). (b) and (c) 

show (110) Laue back reflection diffraction patterns taken from the matrix. twinned 

region TI and twinned region T2 respectively. \Ve car1 clearly see that the twin TI 

is rotated in the anticlockwise direction with respect to the matrix by 250" 32 about 

the [110] tilt axis while the twin T2 is rotated in the clockwise direction with respect 

to the matrix by 250" 32' about the [I101 tilt axis. Other defects revealed in the 

topograph are inclusions (possibly %)(I), slip bmds (S) and lattice tlistortiorls (A) 

in some regions. 

Figure 1. 

Figure 1. 

* \\brk performed on the Stony Brook 

Synchrotron Topograph?- Bearnline S-19C ' 

h 

* \\brk performed on the Stony Brook Synchrotron Topography Beamline X-19C and and supported by S.4S.l LIarshall Space Figure 2. 

supported by S;\S--\ Ilarshall Space Flight Center. Flight Center.

46 

F 

Lamellar Twinning in p-Quaterphenyl Crystals * / X19C I 

William M. Vetter and Michael Dudley (SUNY Stony Brook) 

Flat leaves of p-quaterphenyl with their (001) faces dominant are also common. 

Most of these are twinned. The twins occur as narrow lamellae, visible by optical 

microscopy as pairs of parallel lines about 12pm wide, running along [OlO]. Two of 

these lamellae are marked T in the x-ray topograph shown in figure 1. Topographic 

images of the lamellae may be observed as narrow lines displaced from the images 

of their matrix, or in some reflections, coincident. For one of the lamellae, Tz, all 

contrast vanishes when g = (201). The absence of lattice strain associated with 

this lamella implies that its twin plane is (201). The other lamella, TI, has another, 

unidentified twin plane. 

The lamellae do not extend continuously along the [OlO] direction throughout the 

crystal. Where they terminate, dislocations extend into the matrix. Dislocations 

also originate at the twinning plane, and either curve back to terminate there, or 

extend to the crystal's surface. Some of them, Dl, are in maximum contrast in 

the g = (110) reflection shown in figure 1, and extinguish when g = (110). Those 

labeled Dz, behave oppositely, extinguishing when g = (1TO). Both Dl and Dz have 

minimal contrast when g = (001), a reflection almost orthogonal to (110) and (IIO). 

It may be concluded by the g b = 0 criterion the Burgers vectors of Dl and Dz 

are b = [I101 and b = [110]. As their lines roughly follow the same directions, they 

are mainly screw in character. 

Figure 1. 

* Topography was carried out at the Stony Brook Synchrotron Topography Facility, 

rn 

cn Beamline XIS-C, at the NSLS, which is supported by the U.S. Department of Energy. 

I Macroscopic Twinning in p-Quaterphenyl Crystals * I X19C I 

W.M. Vetter and M. Dudley (SUNY, Stony Brook) 

p-Quaterphenyl crystals form thin, colorless leaves when grown from toluene 

solution by the temperature gradient method. Macroscopically twinned bicrystalline 

leaves whose (001) primary faces are inclined to one another by 36.4' (which may 

be measured by optical goniometry) occur frequently. However, topographs of few 

such crystals don't show extensive asterism in the region of its twinning plane. 

Figure 1 shows a white beam synchrotron Laue pattern of such a specimen. This 

crystal has one small corner macroscopically twinned in this way, which is free 

of gross distortion. The (001) face of the larger parent matrix grain is oriented 

perpendicular to the incident beam. In figure 1, no misorientation between the 

diffraction spot3 arisiqg from the matrix and twin occurs for spots of the zone 

(i.e., {412), {211), (2211, etc.), the direction of shear between the twin and 

matrix lattices. Additionally, the angle between [OOl] and [I021 is 18.2", half the 

observed twinning angle in the crystal. Therefore, the twin plane may be assigned 

as (201). 

Figure 1. 

* Topography was carried out at the Stony Brook Synchrotron Topography Facility, 

Beamline X19-C, at the NSLS, which is supported by the U.S. Department of Energy.

1 Xl9C 

m I Surface Scattering From the C4E1 Oil-lulicroemulsion Interface 

F 

0 

0 S. M. Williams, Z. Zhang, D. M. MitrinoviC, M. L. Schlossman (U. of IL-Chicago), 

and Z. Huang (BNL) 

We have made x-ray scattering measurements from the oil-microemulsion interface 

of a (butoxyethano1)-water-decane mixture at 35OC. The ultra low surface 

tension of this interface gives rise to strong thermal fluctuations. 

No bicontinuous structure has been observed in bulk C4E1 microemulsions, enabling 

us to analyze the effects of these large interfacial fluctuations without the 

added complexity of layering at the interface. Specular reflectivity data was measured 

to determine the electron density profile normal to the interface. IVe also 

made surface diffuse scattering measurements near the specular condition. This 

probes the interfacial thermal fluctuations in the plane, which we characterize by 

capillary waves. Both types of data mere analyzed using the distorted wave Born 

approximation. 

Initial analysis of the reflectivity data from the oil/microemulsion interface indicated 

a roughness of about 54 11. However, when this value was used in the analysis 

of the diffuse data, we could not obtain a satisfactory fit. Upon increasing the 

roughness parameter to 61 Awe obtained an excellent fit to the diffuse clata with a 

surface tension of about 0.17 dynes/cm. 

This discrepancy is a consequence of the low surface tension of the interface. 

There is both a diffuse and reflected signal at the specular position, but in high 

surface tension samples, the diffuse signal is much smaller. When the surface tension 

is low enough, the tliffiise signal is of the same order as the reflection, making it 

necessary to separate the two signals in the analysis of the data. Figure 1 shows 

the raw reflectivity tlata (54 A) antl the data after the diffuse signal has been 

sltbtracted (60.8 ii). Using the interfacial roughness value obtained from the pure 

reflected signal, me were able to obtain an excellent fit of the diffuse tlata with a 

sl~rface tension of ~0.22 tlynes/cm (figure 2). 

This sample tlemonstratetl that the interfacial fluctuations in these ultra low surface 

tension systems are the result of capillary waves. The interplay that we found 

between the specular antl diffuse signals can now be applied to systems composed 

of stronger anlphiphiles where layering may be present at the interface. 

Figure 1. Specular reflectivity data from 

- 

0.001 

0 0.1 0.2 0.3 0.4 0.5 0.6 

the oil-microemulsion interface. The raw Detector angle p ( ) 

data yields a roughness of 54 -4. After the 

diffuse signal is subtracted. the rough- FigIre 2. Diffuse scattering data from 

ness is found to be 61 -$. the oil-microemulsion interface. 

Surface Scattering from the CI0E4 Oil-h/Iicroemulsion Interface 1 Xl9C 

S. M. Williams, Z. Zhang, D. M. Mitrinovic, M. L. Schlossman (U. of IL-Chicago), 

and Z. Huang (BNL) 

X-ray reflectivity and surface diffuse scattering were measured from the oilmicroemulsion 

interfaces in the 3-phase region in the ternary mixtures CloE4-waterdecane 

and CloE4-water-tetradecane. The ultra low surface tension at these interfaces 

gives rise to strong thermal fluctuations. In addition, the microemulsion 

phase in these mixtures is believed to be bicontinuous. This has been predicted to 

produce interfacial layering at these strongly fluctuating interfaces. The systems 

studied have interfacial roughnesses ranging from 150 A to over 200 a. 

Reflectivity and off-specular diff~~se scattering data were measured from both 

samples. While the specular peak tracks incident angle, the surface enhancement 

associated with the diffuse scattering remains at the critical angle. In smoother 

samples, for wave vectors at which the magnitude of the specular signal has decayed 

to the order of the diffuse signal, the two peaks are well separated. In these rough 

samples. the specular peak falls off so quickly for wave vectors slightly greater than 

the critical wave vector for total reflection that the specular and diff~~se signals 

are of similar strength at the critical angle, making the reflectivity data clifFicult 

to interpret. Initial analysis of the CIOEL-water-tlecane sample established a lower 

bound on the roughness of 200 (Fig. I). 

The specular signal from theCIOEzl-water-tetratlecane interface drcavs less 

rapidly. Figure 2 shows the data in the Qz range from 0.01 to 0.028 k'. Below 

the critical Q, of 0.01 .kl, there is only one peak. At QZ = 0.014 A-', the 

two peaks begin to separate, antl at 0.016 ,Ap' they are resolved. Preliminary analysis 

of these data indicates a roughness of about 150 A and a surface tension of 

0.01 mN/m. Further analysis of these data will also be usrf~d in separating the 

dith~se and speci~lar sigr~als in the rougher sample. 

Figure 1. Figure 2.

+ P 

m 

-l 

X-ray Reflectivity From a 1,1,2,2 Tetrahydrohenicosafluorododecan01 

Monolayer at I XISC / 

the Water-Hexane Interface 

Z. Zhang, S.M. Williams, D.M. MitrinoviC, M.L. Schlossman (U. of Illinois at 

Chicago), and Z. Huang (BNL) 

Addition of the soluble surfactant 1,1,2,2 tetrahydrohenicosafluorododecanol (de- 

noted FC120H) to hexane (2 mmol concentration) results in the formation of a 

monolayer of FC120H at the water-hexane interface. X-ray reflectivity from this 

water-(FC120H)-hexane interface combined with grazing incidence diffraction from 

an FClzOH monolayer at the water-vapor interface is analyzed to determine that 

the FC120H monolayer at the water-hexane interface is a solid at T=32"C. The 

existence of the solid monolayer at the liquid-liquid interface is due to a delicate 

balance of solvation and Van der Waals energies in this system. At T=4S°C most 

of the FClzOH molecules are desorbed from the interface. 

The two reflectivity curves (at T=48OC and T=32OC) from the water-(FCl2OH)- 

hexane are shown below. The measurement at T=48OC can be analyzed as a rough 

interface between two bulk phases. A Born approximation analysis of these data 

yields a surface roughness, u=0.38f 0.03 nm. 

The data measured at T=32OC were fit using the Born approximation and an 

electron density profile that models the surfactant monolayer as a simple layer with 

equal roughness on both sides that is sandwiched between the two bulk phases. 

The layer thickness determined by the fit to the data is given by L = 1.210f 0.085 

nm. This thickness is 0.4 nm shorter than the full all-trans length of the surfactant 

molecule, but is essentially the same as the length of the fluorinated part of the 

molecule. This indicates that the reflectivity is sensitive only to the fluorinated 

region of the molecule, most likely because the electron density contrast of the wa- 

ter with the surfactant hydrocarbon headgroup is too small. The electron density 

of the layer (normalized to the density for bulk water) is 1.96f0.09. This den- 

sity at the liquid-liquid interface is consistent with the normalized density (2.01) 

of 2-dimensional crystallites of FClzOH at the water-vapor interface (at the same 

temperature) as determined by grazing incidence diffraction. Grazing incidence 

diffraction from the liquid-liquid interface was not possible because the ratio of sig- 

nal to background was too low. This combined analysis of these two measurements 

indicates that the monolayer at the liquid-liquid interface is in the solid phase. 

Figure 1. X-ray reflectivities of FClzOH monolayer at T=32OC and 48OC. 

I. 

I X-ray Reflectivity from the Water-Hexane Interface I X19C I 

Z. Zhang, S.M. Williams, D.M. Mitrinovic, M.L. Schlossman (U. of Illinois at 

Chicago), and Z. Huang (BNL) 

X-ray reflectivity was used to study the roughness of the pure hexane-water 

interface. To probe this buried interface the x-rays penetrate the upper phase 

(hexane). X-ray absorption and bulk scattering from the upper interface require 

that the sample cell be reasonably small. However, since the interfacial tension 

of this common liquid-liquid interface is similar to the water-vapor interface, the 

interface will be very curved for a small sample. The cell windows are slanted from 

the vertical as a gross adjustment to flatten the interface. A fine adjustment is still 

needed to reduce the macroscopic curvature of the sample to be much less than the 

angular resolution of the detector (as determined by slits). This is accomplished 

by rotating the sample cell about an axis collinear with the x-ray beam. Due to 

non-equilibrium pinning of the contact angle at the cell window, this rotation twists 

the entire interface and results in a strip of the interface that is very flat. With 

these two adjustments the measured reflectivity below the critical angle for total 

reflection is near 100% and reflection measurements can be collected using standard 

procedures. 

The figure below shows the x-ray specular reflectivity versus the wave vector 

normal to the hexane-water interface at 32.00 f 0.02 OC (n-hexane from Sigma, 

99+%, water produced by a Barnstead Nanopure system). The fit yields an inter- 

facial roughness of 0.33 f 0.03 nm. Comparison with an earlier measurement of 

the pure water-vapor interface (at a similar wave vector resolution) for which y = 

72 mN/m and u=0.27 nm (at T = 20°C) yields yh ,,,, ,-,,t,, E 50 f 2 mN/m, in 

good agreement with the literature value of 51.4 mN/m obtained from macroscopic 

interfacial tension measurements. 

Figure 1. Reflectivity data as a function of wave vector normal to the interface.

+ / Kinetics of Monolayer Electrodeposition 

1 X20A 

0 

co A.C. Finnefrock, K.L. Ringland, L.J. Buller, H.D. Abruha, J.D. Brock (Cornell 

Univ.) 

In many electrochemical systems, one or two monolayers of an adsorbate may 

be deposited at a potential less negative than the Nernst potential. The growth 

mechanisms involved in this secalled underpotential deposition (UPD) have been 

the subject of intense controversy for over a decade. Static x-ray measurements 

(Tidswell, et al.) on the UPD of copper on Pt(ll1) in the presence of chloride in 

an HCI0.t solution have noted the existence of a structure ascribed to an aclsorbetl 

incommensurate CuCl bilayer. 

\Ve have performed a series of voltage-step experiments on this system, simultaneously 

recording the resldtant current transient and time-resolved surface x-ray 

scattering. The x-ray profiles are fit to a simple trapezoidal form, and the characteristic 

time scales are shown in Figure 1 (blue). These indicate the ordering of 

the twedimensional incommensurate CnC1 overlayer in real time. The time for the 

current transient to fa11 to 5% of its initial vahe is also shown in Figure 1 (red). 

Note that in all cases. the cwrent transient occnrs on a shorter time-scale than the 

emergence of the scattering peak from the two-dimensional overlaver. 

The exponential scaling of the time constant for ordering vs. l/dl demonstrates 

that this behavior can be explained as a nncleat ion process. Fnrtherrnore, this 

m~clcation consists of clusters which are two-dimensional and compact (non-fractal). 

For a particular voltage transition, we have perforrnetl an entire time-tlependent 

q-scan. By monitoring the time-tlependc~~t widths of the x-ray peak, we see a 

narrowing corresponding to the increasc in the mean clnster size. \.Ye can fit the 

entire q-tscan, as shown in Figure 2, with x' = 1.04. From this analysis, we can 

extract the rate of cll~ster nucleation antl the growt,h rate for an individual clustcr. 

io2 . - 

Generated surface 

lo-'* 0.02 004 -002 ,,/ 

1 / 6' (mv-f) 

0.06 

qL (A-') -0.w 10 

time (seconds) 

Figure 1. Characteristic rise time versus Figure 2. Surface generated from a few- 

applied voltage. parameter fit to the y-tscan. 

The Dynamic Evolution of Charge-Density Waves I X20A 

K.L. Ringland, A.C. Finnefrock, Y.P. Li, S.G. Lemay, R.E. Thorne, J.D. Brock 

(Cornell University) 

The presence of a charge-density wave (CDW) in a crystal creates x-ray scattering 

peaks that flank the crystal's Bragg peaks. These CDSY peaks exhibit a lineshape 

that is dependent on the degree of order in the CD\\- and are significantly different 

when the CDIV slides and when it is stationary. Investigating the evolution of 

the CDSV as it relaxes from the sliding state to the stationary state allows us to 

better understand the interaction of the deformable CDW with the randomly placed 

impurities in the crystal. 

\Ye applied a continuous square-wave current to a NbSey crystal for several tem- 

peratures between 80K and 1lOK. The x-ray scattering in the c* (transverse) direc- 

tion was measured by stroboscopic averaging over many periods of the square-wave 

at each q point. (Fig. 1) 

If we nse a model for CDW evolution which treats the CDM7 as an elastic object 

and the CD%-impurity interaction as a quenched random field, we can derive the 

equation of motion for the scattering intensity. 

where

46 

C3 

I Atomic Structure of the Passive Oxide Film Formed on Iron I X20A I 

M.F. Toney (IBM Almaden Research Center), A.J. Davenport (UMIST/U. Manch- 

ester), L.J. Oblonsky and M.P. Ryan (BNL) 

Passivating oxides form on metals and provide corrosion protection. Although the 

oxide structure largely determines the films protective properties, this structure is 

often unknown, even for elemental metals. The structure of the passive film on iron 

has been the subject of particularly intense study [I], but there is still no consensus 

on questions as basic as to whether the film is amorphous or crystalline, much less 

on the atomic structure. To resolve this question, we have conducted in-situ and ex- 

situ X-ray scattering experiments on the passive film formed at high potentials on 

Fe(ll0) and (001). The Fe crystals were passivated by potentiostatic polarization 

for one hour at +0.4V vs. MSE in borate buffer (pH 8.4). Our methodology is to 

collect a complete data set ex-situ (where the background scattering is small), and 

then to collect selected in-situ data to compare with the ex-situ experiments. In 

such a comparison (see Figure) there is excellent agreement, which demonstrates 

that the passive film formed under these conditions is not altered by emersion. 

The data show that the film is crystalline with a small crystallite size of -- 50A and 

has a well defined orientation with the substrate. A quantitative crystal refinement 

of the integrated diffraction intensities shows that the film structure is not one 

of the bulk forms of iron oxide (see figure). Rather the film structure (LAMM 

structure) is based on the spinel Fes04, but with considerable cation vacancies on 

the octahedral and tetrahedral sites (80% and 66% occupancies, respectively) and 

with cations occupying octahedral interstitial sites (12% occupancy) 121. 

These results resolve the controversy surrounding the film structure and provide a 

basis for understanding film properties important for corrosion protection, including 

the behavior of passive films formed on engineering alloys, such as stainless steel. 

[I] H. H. Uhlig, in Passivity of Metals, edited by R. P. Frankenthal and J. Kruger 

(The Electrochemical Society, Inc., Princeton, NJ, 1978), p. 1. 

[2] M. F. Toney, A. J. Davenport, L. J. Oblonsky, M. P. Ryan, C. M. Vitus, Phys. 

Rev. Lett. 79, in press. 

- 2 ex-rilu doh 

. in-rilv doto 

Figure 1. Measured and best fit structure factors for a subset of the diffraction 

peaks for film grown on (a) Fe(001) and (b) Fe(11O). 

- 

X-Ray Diffraction Studies of CoPtCr Thin Films for Magnetic 

Recording Media 

X20A 

M.F. Toney (IBM Almaden Research Center) and M.F. Doerner (IBM Storage 

Systems Division) 

The areal density in magnetic recording in presently increasing at a 60% com- 

pound annual growth rate (CGR). To maintain this rate of increase, the hard disk 

drive industry must develop magnetic disk media with magnetic properties (e.g., 

coercivity, signal-to-noise ratio) that are superior to presently used media. One 

approach to this is through the use of alternative underlayers (i.e., the seed layer 

beneath the media). This underlayer has an important influence on the structure 

of the media layer and understanding this relationship (and the consequent effect 

on the magnetic properties) is a key to developing better magnetic media. 

We have used grazing incidence X-ray diffraction to determine the structure of 

CoPtCr media deposited on several different underlayers. These measurements 

were made on actual thin film disk coupons. Representative results are shown in the 

figure for 500A Cr underlayer (a commonly used underlayer) and ~ooAc~T~/~ooAc~ 

composite underlayer. These data show that the media are both highly (11.0) 

oriented (although to a greater extent for the CrTa/Cr underlayer), small grained 

and highly faulted (broad peaks). While the data show these media are hcp, the 

presence of a weak fcc(200) peak is apparent at Q = 3.45k1, particularly for the 

Cr underlayer. This means that a small fraction of the media forms into the fcc 

structure. A quantitative analysis of the peak widths shows that in both films the 

particle size is about 100 by 150 A, along (100) and (002) directions, respectively. 

However the stacking fault density (sum of growth and deformation faults) is much 

higher for the media on the Cr underlayer (a! + /3 = 0.30) than for the CrTa/Cr 

underlayer (a +/3 = 0.18). Since such faults have localized fcc-like regions in the hcp 

matrix, the media on the Cr underlayer has a higher percentage of fcc-like regions 

(about 18% including the regions in the faults and in the fcc part of the crystal) 

compared with the CrTa/Cr underlayer (about 7%). This structural information 

provides a better understanding of the media coercivity and magnetic viscosity [I]. 

[I] P. Dova, K. 0' Grady, H. Laidler, M.F. Doerner, and M.F. Toney, paper 

AB-05, MMM-Intermag Conference 1998. 

Figure 1. Diffraction pattern from CoPtCr media. Some of the diffraction peaks 

are indicated.

X-ray Scattering Studies of Thin NixCol-,, x = 0.225 Films: Discov- I X20A / 

ery of a Reentrant Phase Transformation 

- 

h1.F. Toney and D. Weller (IBRI Almaden Research Center), and A. Carl (Gerhard- 

Rlercator U. Duisburg) 

Carl et al. found that Ni,Col-, films exhibit an z 15% enhanced magnetization 

for x -- 0.25-0.30 relative to x=0.22 and 0.35 [I]. It was postulated that this is due 

to an hcp/fcc/hcp sequence of phase transitions as a function of x. To confirm this 

unusual (reentrant) sequence of phase transitions, me conducted X-ray scattering 

measurements of these polycrystalline thin films. These measurements are shown 

in Figure 1. The single peak at z 1.55k1 shows that for x=31.4 and 24.3% the 

films are hcp, while the presence of additional peaks at -- 1.05 and 2.1Ap' shows 

that for x=26.2% the film is a mixture of fcc and hcp structures. hleasurements on 

other films showed that for 0.25 < 0.29, the films had the mixed fcc/hcp structure, 

while for x outsitlc this range, the films were purely hcp. 

It is reasonable to postulate that the forrnation of the fcc phase in driven by 

chemical ordering, since a related effect was observed for Copts [2]. To test this 

idea, experiments were conducted to search for chemical ordering peaks in the mixed 

fcc/hcp films with the X-ray energy tuned just below the Co K edge (to enhance 

the contrast between Ni and Go). However, we folnltl no indication of short or long 

range chemical order. Thus, the driving force for the forrnation of the hcp phase is 

still unclear. 

[I] A. Carl, D. Wller, R. Savoy, and B. Hillebrantls, AIRS Symposium Proceed- 

ings 343, 3.51 (1994). 

[2] G. R. Harp et al., Phys. Rev. Lett. 71, 2483 (1993). 

Figure 1. Scans along (10L) (in hexagonal units) for highly (111) textured SiCo 

have been offset for clarity. 

Small Angle X-ray Scattering from Silica Aerogels / X20C I 

L.B. Lurio, A.R. Sandy, S.G.J. Mochrie (hIIT), N. Mulders and h1.W.H. Chan 

(Pennsylvania State University) 

Silica aerogel is a highly porous material composed of strands of spheres assem- 

bled to form a dilute fractal network up to a length scale

Phase Formation Sequence of Nickel Silicides from Rapid Thermal 

Annealing of Ni on 4H-Sic 

X20C 

L.D. Madsen (Uppsala U. and U. of Illinois), E.B. Svedberg, H.H. Radamson 

(Linkoping U., Sweden), C. Hallin (Linkoping U. and ABB Corp. Research, Swe- 

den), B. Hjorvarsson (Uppsala U., Sweden), C. Cabral, Jr., J.L. Jordan-Sweet and 

C. Lavoie (IBM T.J. Watson Research Center) 

Nickel films were ultra-high vacuum sputter-deposited at 400°C onto 4H-Sic. 

These films were cubic and highly -oriented with a 6-fold in-plane symmetry. 

Rapid thermal annealing (RTA) at 3OC/s resulted in the following phase sequence: 

The Ni2Si was orthorhombic and fully formed at 770°C. Rutherford backscatter- 

ing (RBS) showed that the films had distinct layering in terms of composition with 

carbon distributed throughout. Atomic force microscopy (AFM) showed a seven 

fold increase in roughening and in-plane feature size after RTA to llOO°C. 

I X-ray Scattering Study of Ordering Kinetics in CuAu * I X20C I 

0. Malis and K. F. Ludwig (Boston Univ.) 

In situ x-ray scattering experiments of the kinetics of phase transition in CuAu 

were performed to investigate the intricate morphologies that emerge during the sub- 

lattice ordering of the low temperature ordered phase (CuAuI) following a quench 

from the disordered phase. The results of this study indicate a subtle competition 

between the metastable modulated phase (CuAuII) and the stable CuAuI. 

The time evolution of the CuAuII modulated and CuAuI superlattice peaks near 

(110) for quenches from 703K to 653K and 643K is studied (Fig. 1). The ex- 

periment shows that CuAuII satellite peaks are generated at early times and that 

the persistence of these peaks is related to the quench temperature. At shallow 

quench temperatures or early times the modulated state is favored while at lower 

temperature or later times the ordered phase dominates. 

The ordering kinetics can be strongly altered by changing the prequench state 

from a disordered phase to a modulated phase. The growth of the ordered state 

is found to be strongly reduced for a quench from the modulated state. These 

experimental results were found in qualitative agreement with Langevin simulations 

based on the effective medium theory (K. R. Elder, 0. Malis, K. F. Ludwig, B. 

Chakraborty and N. Goldenfeld, in preparation). 

One interesting feature observed in the experiments and not in the simulations 

is a shift in position of the x-ray peaks with time. This motion arises from changes 

in both the lattice spacing and modulation wavelength. Examination of the funda- 

mental (200) peaks indicates that, at the temperatures and time scales discussed 

above, most of the lattice has already relaxed to its tetragonal shape. More signif- 

icant is the shifting of the satellite peaks away from the central superlattice peak. 

These changes are typically quite large and occur in the early to intermediate time 

scales. For example in the quench to 643K the modulation wavelength decreased 

from approximately 15.6 to 11.5 lattice constants on a time scale of 300s. We are 

currently investigating these effects with Monte-Carlo simulations using Embedded- 

Atom cohesive energy calculations. 

-6-1 

- - total - 

--r---___ 

< - / 

Figure 1. Time evolution of the integrated peak intensities for quenches from 703K 

to 653K and 643K. 

* This work was supported by NSF Grant DMR-9633596.

F 

4 

t\3 

Determination of Polymer Chain Orientation in Rubbed Polyimide XZOC 

1 Films 1 I 

J. Sands (Pennsylvania State University) 

The role of rubbed polyimide films as templates to induce alignment of liquid 

crystal molecules is an unexplained phenomenon. The near surface orientation of 

polymer chains produced during buffing is dependent upon the distance over which 

the films are buffed. applied load. and film thickness. Despite the small macroscopic 

force applied at room temperature (= 200 Pa). a substantial orientation of polymer 

chain segments at the surface occurs. + This is surprising given that the bulk polyimide 

has high tensile modulus (10.5 GPa). tensile strength (300 hIPa), and glass 

transition temperature (Tg = 400°C). Grazing incidence x-ray scattering (GIXS) 

has been used to study the degree of near surface orientation as a fnnction of applied 

loatls. GIXS results indicate that the ~nechanisrn for the observetl orientation 

ill rubbed polymer films is driven by yielding of polymer chains aligned perpentlicnlnr 

to the rubbing direction. The yielding occurs since microscopically there are 

large stresses. A model for the ~ncasnrctl orieritational changes tlemonstrates that 

the orientation of the polymer chains is a surface affect t,hat propogatcs 100A into 

the film for a given set of Ioadi~lg contlitio~~s. 

X-Ray Resonant Raman Scattering Study at the Nd Lg Edge on 

Nd2Fe14 

X2 1 

F. Bartolomk, J. hl. Tonnerre. L. She. D. R~OLLY (CNRS), and C-C. Kao (BNL) 

IVe report on the work performed during the first week of measurements at X21 

beam line, allocated during the 1-4/97 cycle to the General User Proposal 3136. 

entitled X-ray resonant Raman scattering study at the L2.3 edges of Nd in the 

Nd2Fel~B permanent magnet system (local contact: Dr. C-C. Kao). Resonant 

inelastic (Raman) scattering spectra were recorded around the Lg absorption edge 

energy, monitoring the 4d5/2,3/2 + 2pgI2 radiative decay channel (LRr.15). About 

15 spectra mere recorded at different fixed incident photon energies, hwl, around 

the L:$ edge as a fi~nction of the scattered photon energy. hw.2 (IXS scans, four 

of them are sllowri in the figure, left panel). Two additional absorption channels 

(labeled Al,A2 in the figure) besicics the strong dipolar 2p+5d (labeled B) mere 

identified. with excitation energics lying 5-10 eV below the absorption whiteline 

energy. The quadrupolar origin of these pre-edge featnres is evidenced by its lower 

energy position and the qnalitative agreement with recent calculations. In order to 

directly compare the inelastic Rnman scattering with XhICD spectra the evolution 

of the intensity of the dipolar and q~~atlrupolar peaks in the "fixed hwl" spectra was 

morlitoretl as a fimction energy, thus keeping the energy transfer constant and fixed 

to the corresponding valucs of each observetl feature (CFS scans). The corriparison 

between X-ray RanIan and L:r XAICD spectra (see fignre, right panel) show a one-toone 

correspondence. Thr prc-ctlge features appearing at thc same incitlcnt energies 

in both teclnliqws can be assigrletl to quatlrupolar electric transitions within a 

simple model. Thr rrs~~lts of this cxperi~nent together with cornplctuctary results 

have been acceptrrl for pnblication (F. Bartolomd rt al. Phys. RPzl. Lett. 79 

(1997).) 

Figure 1. RISS intensity at four incident energies (left panel) and CFS scans (right 

panel. thin lines) together with MICD (thick line) at Sd La-edge on Sd3Fel~B. 

RISS data are scaled as indicated in both panels.

46 F 

-4 

( Inelastic X-ray Scattering from Single Crystal Sodium and Lithium * ( X21 ( 

P. Chow (U. Houston), J.P. Hill (BNL), C.-C. Kao (NSLS), and B.C. Larson 

(ORNL) 

Advances in synchrotron instrumentation [I] coupled with the capability of ab 

initio calculations in the last few years [2] provide an opportunity to study the 

dynamical response the many-electron system in metals. A number of low-Z metals 

have been investigated in the past decade. Still, reliable experimental S(q,w) data 

are required to advance the understanding of many-body physics. 

At X21, we have continued our measurement of the dynamical response of single 

crystal Na, the proto-typical free-electron metal. We grew a 1x1~5 cm3rod of single 

crystal of sodium of excellent quality. After determining the orientation of a test 

piece, we sawed a 1 mm thick slice of Na as our sample, chosing an orientatin such 

that we could measure S(q,w) in the [001],[110] and [Ill] high-symmetry directions. 

Our aim was to measure the low-q plasmons of single crystal Na and the higherq 

response function in Na in those directions. In our recent run, we have made 

a complete set of measurements of Na in the [110] direction, and a partial set of 

measurements of the [Ill] plasmons in Na, including a careful measurement of the 

empty cell background and the energy resolution. These results are being analyzed, 

first to account for the scattering that arises from excitations related to the band 

structure of the crystal, and ultimately to assess the role of the electron-electron 

correlations in the simple metal Na. 

In addition, we have made careful measurements of the excitation spectrum of Na 

and Li single crystals at large wave vectors in high-symmetry directions, in order to 

probe many-body local-field effects and off-diagonal contributions to the dielectric 

function of simple metals. We have performed S(q,w) measurements of this type 

on both Na and Li single crystals. The Na measurements required long counting 

times (due to the high absorption) whereas the Li scattering was relatively strong. 

Analysis is in progress. 

[l] C.C. Kao, K. Hamalainen, M. Krisch, D.P. Siddons. T. Oversluizen, and J.B. 

Hastings, Rev. Sci. Inst. 66(2) 1995. 

[2] A. G. Eguiluz, A. Fleszar, and J. Gaspar, Nuclear Inst. and Meth. 96, 550 

(1995). 

* This work was supported by NSF DMR-9208450 and DOE Div. of Materials Sciences 

LO under contract with Lockheed Martin Energy Systems. 

I The Evolution of the Cu K@1.3 Spectrum From Threshold I X211 

M. Fritsch, M. Deutsch (Bar-Ilan U., Israel), and C.C. Kao (NSLS) 

The photoexcited Cu KPI,~ spectrum was measured near the K edge, complementing 

previous measurements of the Kal,2 lines. 

Below the edge, 5 8980 eV, a resonant Raman behaviour was observed (Fig. 

I), showing the characteristic linear dispersion of the peak position, intensity decrease 

and lineshape distortion with decreasing excitation energy. The expected 

line narrowing at the edge is also observed. 

From the edge up to -- 15 eV higher the individual lineshape is lorentzian, indicates 

contributions from the diagram lines only. No other transitions contribute 

here to the lineshape. 

Above 8995 eV increasingly larger changes are observed in the lineshape. Fig. 

2 shows the broad shoulder that develops on the low-energy side of the line. The 

energy threshold for this feature, as well as full-sperctrum fits based on Dirac- 

Fock ab-initio calculations, assign this structure to 3d spectator hole transitions. 

The cross section for this transition rises smoothly and continuously from zero, 

without any abrupt jumps, showing the ls3d two-electron excitation to be a highly 

pure shake-off process. This is somewhat surprising, since the outer 3d orbital is 

expected theoretically to yield shake-up (rather than shake-off) lines, the crosssection 

of which changes abruptly at the edge. A detailed analysis is underway. 

This work is supported by the Israel Science Foundation, Jerusalem. 

Figure 1. The KPI,~ evolution near 

thereshold. 

i.885 8.890 8.895 8 900 

EemNsmn ['"I 

Figure 2. The 3d spectator shoulder 

growth from threshold, 10-15 eV above 

the K edge.

tj 

F 

-4 

+ 

High Resolution Inelastic Scattering Study of GaN 

X21 

K. Hamalainen: S. Huotari, S. Manninen (U. Helsinki, Finland), and C.-C. Kao 

(NSLS) 

We have measured the dynamical structure factor S(Q, w) of a single crystal 

GaN with high energy resolution inelastic X-ray scattering. GaN has relatively 

large direct bandgap and is a promising semiconductor material for example for 

blue laser applications. The study concentrated on the verification of the position 

of the bandgap (Q and E). and on the study of the band structure. 

The GaN is highly absorbing already at 10 keV and the count rate for the inelastic 

scattcring cross section is extremely low. However, clue to the very low background 

(less than one count in 5 minutes), we were able to clearly separate the bandgap 

features from the background. We measured the inelastic scattering cross section at 

several symmetry points. Due to the strong bragg peaks, we could not always examine 

the transition at all high symmetry points (for example the direct transition). 

instead we had to study it at the positions of forbidtlen bragg reflections. 

The momentum transfer in the scattcring process is relati\rely high antl the dipole 

approximation starts to fail. This has both a negative and positive impact: it make 

the calculation of the transition rnatrix elements more difficult but, on the other 

hand, it can add more weight on the optically forbitltlen transitions and makes it 

possible to study different features of the bnntl structure. 

The theoretical analysis of the spectra will be based on band structure calculation 

including proper matrix elements beyond the dipole approximation. The detailed 

calculatiolr rleetls extensive summation over a11 allo~cd nlonirntunl transfer vectors 

over the reciprocal space. h tletailetl ;m;dysis of the data antl the numerical 

calculations are in progress. 

I Resonant Inelastic Scattering in NdzCu04 I ~211 

J.P. Hill, C.-C. Kao, W.A.C. Caliebe (BNL), h1. Mastubara, A. Kotani (ISSP, 

Tokyo), J.L. Peng and R.L. Greene (U. AIaryland, College Park). 

Understanding the normal state electronic properties of the high-Tc copper oxides 

is important as a prerequisite for a theory of high temperature superconducitivity. 

In addition, the properties themselves are highly unusual. exhibiting non-Fermi-like 

behavior and have attracted much interest. both in this context and from a general 

perspective of understanding electronic behavior in other strongly correlated 

transition metal oxides (eg the colossal magnetoresistance maganates). Theoretical 

approaches typically treat the copper oxide planes as the relevant electronic structure 

within a Hubbard-type model. These correctly predict the antiferromagnetic 

insulator ground state in the undoped materials, but do less well in calculating 

excited state properties, in part due to a lack of detailed knowledge of the model 

parameters. Here inelastic x-ray scattering can make an important contribution because, 

unlike other spectroscopies, it can measure the excitation spectrum directly 

without the complicating effects of a core-hole being present in the final state. Further 

the technique offers bulk-like penetration. 

We report resonant inelastic x-ray scattering studies of Nd2C110.1, the parent 

compour~tl of the electron (loped high-Tc family, Nd2-,CeXClt0~~. Resonant scattering 

provides the atltlitional advantage of being an element specific probe, allowing 

the excitations associated with ttie copper orbitals to be prcfercntially probed. A 

resonantly enhanced excitation of 2 counts per min~~te was observed whcn the incident 

photon energy was turiecl through the Cu K-edge. Our results show that the 

anti-l)onding state in the CuO planes is fi eV above the ground state. The cxcitation 

was itlentifietl with the help of numerical calcl~latio~is of the scattering, using 

an Anderson impurity model to tlescribe the Cu(3tl)-O(2p) hybridization. The fi 

eV excitation is only seen at 8990 eV incident energy. The theory also predicts an 

enhancement at 8983 eV, not seen in the cxperirncnt, ;mtl wc speculate that the 

absence of a feature at 8983 eV is associated with non-local (solid-state) effects. 

Amplitude of 6eV Feature 

Figure 1.

t; 

Cn 

Impact of Band Structure and Many-Body Effects on the Electronic 

Response of a Simple Metal Al)* I x21 / 

B. C. Larson, J. Z. Tischler (ORNL), A. Fleszar (U. of Wiirtzburg), and G. 

Eguiluz (U. of TN & ORNL) 

Combined inelastic x-ray scattering and first-principles dynamical response calculations 

have demonstrated that band-structure effects in electronic energy loss 

spectra are much more pervasive than generally realized. High-resolution x-ray 

scattering measurements (~0.75 eV) made on A1 using the X-21 beam line at NSLS 

have shown that band-structure effects have a significant impact on the energy 

loss spectrum of A1 at both small and large wave vectors. In addition to the 

well-known band-structure and many-body local-field factor (LFF) plasmon energy 

shifts, zone-boundary collective state resonances, spectral shifts to lower energies, 

and high energy tails are observed at all wave vectors. Fig. 1 compares calculated 

non-interacting polarizabilities, x0(q,w), for jellium and band electrons. We note 

that the calculations including the band structure contain a sharp dip at ~8 eV, 

an overall spectral shift to lower energies, and a high-energy tail; none of these are 

present in the jellium calculations. The zone-boundary collective state structures 

(generated by energy gaps at the Brillouin zone boundary) are well known; however, 

the spectral shift to lower energies and the tail in the dynamical electronic 

response calculations at high energies are of equal or larger importance for quantitative 

extraction of many-body effects from the shape of energy loss spectra. The 

dynamical structure factor calculations, S(q,w), in Fig. 1 that include the actual 

band structure of aluminum are in remarkably good agreement with the measured 

loss spectrum at a wave vector of 0.71 k ~ in , contrast to the poor agreement of the 

jellium calculations with the measurements. 

The effects discussed above relate to diagonal contributions to the dielectric matrix. 

Measurements along the [OOl] direction have demonstrated the impact of 

off-diagonal effects as well, through the interaction of the band structure induced 

folded-plasmons with single-particle continuum states. 

*Research sponsored by U.S. DOE under contract No. DE-AC05-960R22464 

with Lockheed Martin Energy Research Corp. 

Figure 1. Inelastic x-ray scattering measurements for A1 at a wave vector of 0.71 k ~ . 

Jellium model xo(q,w) and S(q,w) calculations are compared with measurements 

and first principles calculations including band structure. The (complex) LFF values 

for S(q,w) are (0.5, 0.044) for jellium and (0.2, 0.09) for band calculations. 

Inelastic X-ray Scattering around the Metal-Insulator Transition in I x21 I 

0. Miiller, P. Pfalzer, M. Klemm, S. Horn (Univ. Augsburg, Germany), M. L. 

denBoer (Hunter College CUNY) 

The metal insulator transition (MIT) in transition metal oxides has attracted 

much interest over the last decade. Widely studied examples include Vz03 and VOz, 

which show an MIT combined with a structural transition. While the transition 

in V203 is often considered to be Mott-Hubbard, this probably neglects the role 

played by the many atomic orbitals near the Fermi surface, and the situation is even 

less clear for VO2, which may in fact be "more bandlike than correlated." The high 

temperature phase of VO2 is a rutile metal with two molecules per unit cell. Below 

340 K the material becomes a monoclinic insulator, with four molecules per unit cell, 

reached by distortion of the rutile phase and formation of V - V paii-s. Photoelectron 

spectroscopy has been used to study VO2, and the results differ in important ways 

from theoretical predictions. To resolve the evident disagreements, and to further 

study the electronic structure of VOn and the changes it undergoes at the MIT, we 

have carried out inelastic x-ray scattering experiments on well-characterized single 

crystals of VO2, both above and below the MIT and as a function of the momentum 

transfer q. In Fig. 1 we show the energy loss region below 35 eV for the sample in 

its insulating state at room temperature. Several loss features are apparent, which 

are found to disperse with the momentum transfer q (not shown). Also shown in 

Fig. I is a preliminary fit to the spectra, showing it is composed of a number of 

inelastic energy loss excitations, analysis of which is not yet complete. In Fig. 2 

the same spectrum is shown with the sample in the metallic state above 340 K. 

Comparison shows there are important spectral changes associated with the MIT, 

which will shed light on the electronic states involved in the transition. 

Figure 1. Inelastic loss spectrum of VO2 Figure 2. Inelastic loss spectrum of VOz 

at room temperature (insulating) and above the MIT (conducting) and prelim- 

preliminary fit. inary fit.

I Electronic Excitations in Solid Cao by Inelastic X-Ray Scattering I X21 1 

CI 

-4 

o P. W. Stephens. S. Zwerschke (SUNY at Stony Brook). H. Berger (Swiss Federal 

Institute of Technol. Lausanne), and C.C. Kao (NSLS) 

SYe have measured the clynamical structur: factor of a single crystal of C60 with 

an energy resolution of 0.6 eV FWHAI for 0.4A-I < Q < 1.9k1, for Q along (111). 

(110), and (100) directions. The spectra are dominated by an '.on-ball" plasmon 

which disperses from 26 eV at 0.4 k1 to 34 eV at 1.9 k'. 

The lower energy region reveals a more complicated spectr~~m of electronic transitions. 

Fig. 1 (left) below sho~vs the evolution of S(Q. w) in the (111) direction. 

The resnlts may he conlparetl with electron energy loss spectra of polycrystalline 

films recently pnblishetl in [I]. 

One might have expected that the excitation spectrum in this energy range would 

be a property of the single fullerene molecnle. but Fig. 2 (right) shows that there 

is significnnt dispersion with the direction of Q. 

[1] M.S. Goltlcn et nl., ,J. Ph,ys: Condms. Matter 7 8219 (1995). 

C (1 11) direction 

60 - - - . . 


Structure of Electrode Surfaces in the Course of Electrocatalytic: 

Br/AU(100) anf Ag/Pr(lll) during the course of O2 

R.R. AdiiC ancl J.X. Wang (BNL) 

X22A 

Information on the structure of catalytic surfaces. in particular the structure of 

active phases, obtained during the course of reactions is of paramount important 

for the areas of electrocatalysis and catalysis. Such information can help designing 

electrocatalysis with tlesirecl properties and increase the understanding of electrocatalytic 

reactions and these effects are structure-dependent. In this work. the grazing 

angle incidence x-ray diffraction technique has been applied to study Br and Ag 

adlayers. dnring the course of 0 2 reduction on Au(100) ancl Pt(ll1). respectively. 

Structure of Br adlayers was deterrnined on the Xu(l00) electrodes in the absence 

and in the presence of O2 retll~ction in 0.1 A1 HC10.1 solutions. In both cases. 

the c (4 x 24)~45' and c(& x p)R45" phases were found above 0.3 and 0.7 

V, respectively, in agreement with previous work in neutral solutions. Oxygen 

r~d~~ction is completely inhibited by the c(fi x 2fi)R45" Br actlayer. It takcs 

placc only at potentials negative of the low potential limit of the existence of the 

c(& x 24)~45' phase (Fig. 1). 

Ag fornls a hexagonal incornrnensurate hilayer on Pt(ll1) at ~~utlerpotcntials. 

Thc first monolqw, however, has a cornrnensurate (lx 1) strnctnre. A cornplctc 

inhibition of 0 2 rctluction on Pt(ll1) has been ohserved upon deposition of Ag 

~nonolaycr. r\g ato~ns reside in the three-fold synrnetry sites on Pt(ll1). This 

information allows f~~rther analysis of the irhihition of 0 2 r~~111ction as a fimction of 

thc Ag roveragt.. :\ statistical analysis of this inhibition shows that clurir~g rccluction 

0 2 ntlsorbs in a bridge confignration on Pt(ll1). This answers the long-st;tutling 

ql~cstion. which of the thrcr ~nodels of 0 2 adsorption (Pauling's, Griffitt~s' mtl 

'~lxitlgt~") is opcrat,ivc in 0 2 atlsorption on Pt (Inring red~~cti~n. 

Figure 1. (a) Diffracted x-ray intensity from the c(& x 2A)~43"(a) 

Br adlayer as 

a function of potential for Br/-ln(100) in 0.1 11 HClO, containing 20 m\IKBr in 

the absence (thin line) and in the presence (thick line) of osygen. (b) 0 2 reduction 

on r\u(100) in 0.1 11 HC104 in the absence (dashed line) and in the presence of 20 

m\I KBr (full line).

X-Ray Scattering Study of the Calcitewater Interface: Surface 

Structure and Metal Adsorption 

Chemical and physical interactions at mineral surfaces control the transport be- 

havior of metal contaminants in soils and groundwater systems. Atomic-scale struc- 

tural information on metal speciation and reaction mechanisms at the mineral-water 

interface is required to achieve a fundamental understanding of these interactions. 

Calcite is a ubiquitous mineral and an important metal sorbent. While many 

powder sorption experiments have been performed on calcite, almost no in-situ 

atomic-scale structural data is available for adsorbates at the calcite-water interface. 

One unresolved question has been the nature of the calcite surface structure in 

water and air. We have performed X-ray reflectivity measurements of calcite single 

crystals after cleaving in air, in-situ with a thin water film, and after being blown 

dry with Nz gas. In all cases the reflectivity differs from that expected of sharply 

terminated bulk calcite, and is suggestive of relaxation of the carbonate groups in 

the surface layer (Fig. 1). Essentially no difference is observed between the air- 

calcite and water-calcite interfaces. 

We have also studied the adsorption of metals from solution, including Pb and 

Cd. Calcite exposed to Pb solution accumulates a submonolayer of Pb atoms. In 

combination with previous X-ray standing wave studies, our data indicate that Pb 

substitutes for Ca in the surface layer [I]. Exposure to solution containing Cd 

results in a Cd-enriched surface, followed by the appearance of CdCOa crystallites 

which are strained by the underlying CaC03 lattice (Fig. 2) [2]. 

1 N. C. Sturchio et al, Geochim. Cosmochim. Acta (in press). 

2 1 R. P. Chiarello, N. C. Sturchio, Geochem. Cosmochim. Acta 58 (1994) 5633. 

Figure 1. X-ray reflectivity R(q,) of the 

calcitewater interface. 

.----submanoloyer odsorptmn \ 

---crystolllte Formotmn. 13 hours 

-crystollate formotmn. 18 hours , 

2. 05 2. 10 2. 15 2.20 2.25 2.30 2.35 

X22A 

P. Geissbiihler, D. Yee*, L. B. Sorensen (U. Washington, Seattle), P. Fenter, 

N. C. Sturchio (ANL), and E. DiMasi (BNL) "Present address The Boeing Co. 

Figure 2. Reflectivity near the CaC03 

Bragg peak during Cd adsorption from 

solution. Inset: Intensity at the anti- 

Bragg position during Cd deposition. 

Depth-Dependence of Strains in Cu Films on A1N * 

L. J. arti in ex-Miranda, Y. Li (U. of Maryland, College Park), L. K. Kurihara, P. 

Schoen, and G. M. Chow (NRL) 

We have studied the depth dependence of the structure of Cu films deposited on 

A1N substrates via the polyol method. In this method, Cu particles are believed 

to precipitate from solution, and aggregate to form a number of reaction interfaces, 

and a metallic film on the substrate. We have found that this metallic film consists 

of a bulk polycrystalline Cu film as well as an upper layer of (100) textured Cu. 

This layer constitutes as much as one third of the film. 

We have studied the in-plane structure of this upper layer using 8keV X-rays. We 

have found that the structure of the films in this region consists of a distribution of 

lattice spacings that correspond to strains that range between -0.6 and 1 percent, 

as seen in Figure 1. The observed in-plane peaks are superimposed over a wide 

diffused background. The in-plane azimuthal texturing depends on the time the 

solution is left refluxing during film processing as well as the orientation of the 

substrate during the deposition process. Films deposited on a horizontally oriented 

substrate are more textured than films deposited on a vertically oriented substrate. 

Films refluxed for a longer time are less textured than those refluxed at shorter 

times (compare Figures 1 and 2). 

Cu films. 20 mlns hor~zontol. (200) ~n-plane. olpha = 0 

53 0 

phl [degl 

Figure 1. In-plane azimuthal scan of the 4y 920 40 60 80 100 

phi [deyl 

Cu (200) peak of a 20 min H sample at 

grazing incidence. 

Figure 2. In-plane azimuthal scan of the 


* Work supported by NRL and ONR grazing incidence, 

nanostructured materials programs.

I In situ X-ray Diffraction Studies of LiMnz04 in Li Ion Battery Cells* / X22A / 

F 

-3 

co S. Mukerjee, T. R. Thurston, N. h4. Jisrawi, X. Q. Yang and J. LIcBreen (BNL) 

hl. L. Daroux, and X. K. Xing (Gould Electronics) 

The Structural behavior of layered and spinel lithiated oxides such as LiZl\ln2O4 

vary considerably depending on the preparation conditions. The diversity in structural 

properties in turn affects the behavior of these materials when they are used as 

cathodes in battery cells. In situ x-ray diffraction studies of these materials within 

operating battery cells offers an excellent method for understanding ancl improving 

them, specially with regard to their cycle life characteristics. 

Naterials studied as a part of this investigation, were from commercial sources. 

Structural evolution in these spinel compountls could be classified into two groups, 

A and B. Group A had clear two or three phase coexistence, while group B showed 

supressetl two phase coexistence.Although the exact preparation conditions of the 

various samples are proprietary, conlparison of our experimental resdts with those 

of other researchers leads to the conclusion that the group B materials were prepared 

lithiurn rich corrlparetl to group A. The group B materials consequently show 

suppressed structural transitio~is and more importantly better cycle life. This is 

amply exhibited in figure I. In contrast to this the group A materials all showed 

coexistence of two or more phases as evident from figure 2 which shows the cocxisterice 

of three phas~s at x = 0.5 in Li,rhInaO.~. Altho~~gh all the gronp B rnatcrials 

have Ims pronouncctl st,ructural transitions. we have not rneasuretl a single batch 

whew the transitions were corr~plctely supressetl. It may t~lrn ollt to be cornplctcly 

in~possible to suprcss this transition in ~~ntlopetl Li,hInaO.t. 

* This work was supported by CRADA grant No , U. S. DOE. 

Figure 1. 

a (-1 

Fignre 2. 

1 Epitaxial Growth of Electrodeposited "BCC" Copper on Au(100) I X22A 1 

R. Randler, D.h.1. Kolb (U. Ulm). I.K. Robinson (U. of II.), and B.M. Ocko (BNL) 

Scanning Tunneling Microcopy studies of copper electrodeposition on Au(100) 

strongly suggest that the first ten monolayers deposit epitaxially while an instability 

develops at higher coverages which leads to a buckled film(1). Here we report x-ray 

scattering results for electrodeposited copper films below t,en monolayers. Studies 

were carried out using a flame annealed single crystal and an in-situ x-ray scattering 

electrochemical cell. All potentials are with respect to Ag/AgCl electrode. 

X-ray specular ancl nonspecular reflectivities are shown in the figures. The a p 

pearance of the broad shoulcler/peak at about L=2.8 (Fig. 1) results from a thin 

copper film with a CII-Cu layer spacing snlaller than the .4u(100) layer spacing. The 

reflectivities were fit to a real-space model which includes the semi-infinite Au(100) 

lattice terminatecl by epitaxial copper with a Gallssian thickness distribution. The 

best fits give 4.2 CII layers in (c) and 6.5 layers in (tl). For all coverages, the cx- 

tractcd copper layer spacing is 2.85 i 0.03 A which is very close to the (2.885 10 

Au-An spacing. The close agreement between the in-plane and out-of-plane lat- 

tice constants, along with atltlitional diffraction data (See Fig 2), indicates that the 

deposited copper is only slightly tlistortetl from BCC. 

(1) D.ill. Kolb, R..J. Rantller. arid R.I. \Yielgosz, and J.C. Zieglcr, in Electro- 

cherr~ical Synthesis arid llotlification of hlaterials. hIat. Res. Soc. Syrnp. Proc. 

451 p. 9 (1997). 

C '+' 

I 1'0 5 ,o 2'5 ,0 i 5 ., 

(0.O.L) 

Figure 1. Specular reflectivity from 

electrodeposited Cu on --Iu(100). a) 

110 copper (0.3 1-). (b) a copper UPD 

layer (0. I\*). and (cd) copper mdt ilay- 

ers with different deposition times (-0.3 

\*). Dashed lines calculated for ideally 

terminated Xu(100). Solid lines are best 

fits. 

Fignre 2. Sonspecnlar reflectivity (tetragonal 

coordinates) from elcctrotleposited 

Cu on .-\11(100). a) no cop 

per (0.5 1-). b) a copper UPD layer 

(0.11-), ant1 (c \ copper rnultilayer (-0.3 

Y). Dashed lines calculated for ideally 

terminated -iu(100).

Multiple Structures of T1 Adlayers Induced By Coadsorption of Br- 

on the Au(ll1) Electrode Surface 

J. X. Wang and R. R. AdZid (BNL) 

I X22A 1 

The voltammetry curve for the underpotential deposition of T1 on Au(ll1) in 0.1 

M HC104 solution containing 1 mM TlBr (Fig. 1.) shows rarely observed multitude 

of reversible peaks. T1, at potentials negative of peak E, and Br, at potentials 

positive of peak A, form incommensurate close-packed, hexagonal adlayers as in 

the absence of the other species. At the intermediate potentials, three superlattice 

structures are observed which do not exist in the absence of either ~1' or Br-. 

The phase transitions are shown by the potential dependent diffraction intensities 

at (9/13,3/13), (0,1/2), and (0.468,0.468) for the 3 - (m x a), 2 - (3 x &), 

and c(2.136 x &) phases, respectively. The first two phases are commensurate and 

well-ordered, existing in the low-current potential regions between peaks B-C and 

C-D. The diffraction at the (0.468,0.468) position is broad and weak, but does not 

shift with potential in the region between peak D and E. The integrated intensity 

has been measured for in-plane diffractions (L=0.2) up to the fifth order for the 

3 - ( m x m ) and 2 - (3 x &) phases and the part of data are shown in Fig. 

2. The integrated intensities (after corrections) agree with the values (listed in 

Fig. 2) calculated using the models shown in Fig. 1. The ( a x m ) unit cell 

contains 3 T1 and 6 Br. The hexagonal symmetry and the Tl/Br ratio of 112 in 

this phase can be rationalized by the higher partial charge of T1 than Br at the 

rather positive potential. As the T1 becomes more discharged at more negative 

potentials, the Tl/Br ratio becomes 111 and the 2 - (3 x a) phase exhibits quasisquare 

symmetry. Layer spacings in the coadsorbed phases are proposed on the 

basis of the ionic radii of T1+ (2.98 A) and Br- (3.92 A) and will be determined 

from surface rod measurements. 

Figure 1. 

8 (degrees) 

Figure 2. 

X-Ray Induced Transitions in Manganites 

X22B 

D. Casa, V. Kiryukhin, B. Keimer (Princeton U.), J. P. Hill, A. Vigliante (BNL), 

Y. Tomioka, and Y. Tokura (JRCAT) 

Manganites of composition PI--,Ca,Mn03 (x=0.3-0.5) were investigated by 

synchrotron x-ray diffraction in high magnetic fields. At low temperatures these 

materials undergo magnetic field induced transitions from charge-ordered antiferro- 

magnetic insulators to ferromagnetic metals. Surprisingly, diffraction experiments 

on the x=0.3 material revealed that exposure to the x-ray beam itself also dimin- 

ishes the charge order. At the same time, the electrical conductivity is enhanced by 

several orders of magnitude[']. 

During the past year, we have systematically investigated this novel effect. We 

found that an applied magnetic field accelerates the x-ray induced transition for 

x=0.3, and a threshold field has to be applied to induce the transition for larger 

x (2T for x=0.4, and 8T for x=0.5). The lattice domain structure is altered in a 

nontrivial manner by x-ray exposure. The transition occurs only at low temper- 

atures and is reversible on thermal cycling. When Ca is partially substituted by 

Sr, persistent x-ray photoconductivity is observed up to temperatures in excess of 

100K. This may facilitate possible applications of the effect in x-ray detection or 

x-ray lithography. 

In analogy to persistent photoconductivity in compound semiconductors doped 

with DX centers, we argue that the x-ray induced transition is evidence for strong 

electron-lattice interactions of which the Jahn-Teller effect is a plausible origin. 

However, the collective nature of the transition in the manganites, and the associ- 

ated kinetics, require more elaborate models. 

[I] V. Kiryukhin, D. Casa, J.P. Hill, B. Keimer, A. Vigliante, Y. Tomioka and Y. 

Tokura, Nature 386, 813 (1997).

tj 

- 

F 

E 

Surface Structure of Liquid Hg/Au Alloys * 

E. Dihlasi, B. hI. Ocko (BNL), hI. Deutsch (Bar-Ilan U., Israel). H. Tostmann, 

and P. S. Pershan (Harvard U.) 

Catalysis at the surface of binary metal alloys is understood to depend on the 

valence of the two metallic elements, as extra electrons in the dissolved metal act 

to fill unoccupied surface states. Since the catalyzed reaction proceeds at surface 

sites, the tlisorcler frozen into the solid metal surface also plays a role [I]. 

Catalysis at the liquid metal surface has several advantages over that at the 

solid metal: the surface is smooth. particles are mobile, and active centers can be 

refreshed on short time scales. Studies of the rate of formic acid decomposition over 

liquid mercury with different concentrations of dissolved metals have found that the 

addition of higher-valence metals decreases the activation energy of the reaction. 

This was interpreted as indicating that electrons arc localized in covalent bonds at 

the alloy surface [I]. 

To study the effect of dilute alloys on the surface structure of liquid metals, we 

have performed X-ray reflectivity rneasi~rements on liquid mercury alloyed with O.0G. 

0.10. antl 0.13 weight % Au. The reflectivity for the Hg-Au alloys exhibits one or 

more minima (Fig. I), with the swface layering peak somewhat attemmtetl at high 

temperatl~res relative to pure Hg. These data are consistent with a lower density 

s~~rface region (Au depleted) antl a higher density bulk phase (An enriched). \\e 

find a corr~plicatctl tlepcntlcnce on ter~ipcrature, concentration, ard thermal cycling 

that may be related to thc preience of the passivatirlg Hz atmosphere in the sample 

ccll. 

[I] C.-;\I. Schwab. "C;ttalysis on Liquid AIetals". Berichte tler Bunsen-GesellschaR 

SO (1976) 746. 

Figure 1. X-ray reflectivity R(q,) of liquid Hg antl Hg-Au alloys at -2B3C. 

l1.D. acknowledges support from the 1IS-Israel Binational Science Foundation. 

X22B 

Temperature Dependent X-ray Scattering from Liquid Metal Sur- 

X22B 

I faces * 

E. DihIasi. B. LI. Ocko (BNL), RI. Deutsch (Bar-Ilan U.). H. Tostmann. 0. G. 

Shpyrko. and P. S. Pershan (Harvard U.) 

Our understanding of the liquid metal surface lags behind that of the solid. due 

to complications introduced by the lack of long-range order. Features unique to 

liquid metals. such as surface induced layering, have recently been identified through 

surface X-ray scattering. Studies at cliff'erent temperatures reveal characteristics 

inconsistent with the predictions of capillary wave theory. sllowr~ to account well 

for simple liquids. 

\Ve have measured reflectivity and thermal diffuse scattering from liquid Hg and 

In surfaces. Hg was studied between -40°C and +25"C in a high vacuum cell 

equipped with a liquid nitrogen cold finger. A new UHV chamber designed for the 

Harmrtl/BNL X22B liquid spectrometer was 11set1 for rneasl~rcments of In at 220°C. 

For liquid Hg, the reflectivity R(q,) is characterized by a peak at q, % 2.2 A 

with a temperature dependent amplitucle that is related to t11c surface rougtmess 

(Fig. l(a)). Previous studies of liquid Ga [l] revealed that the swface roughness. 

tletlucetl from fits to R(q,), has a temperature tleper~tlencc consistent wit11 tlier~nnlly 

excited c;rpillary waves (Fig. l(b), 0). Similar analysis of Hg rcwals that the surfxc 

roughness decreases more q~~ickly with reth~crtl ternperat~~rc than expected from 

capillary wave theorv. 

\\i. have also measured the t,herrnal diffuse scattering for Hg near the specdar 

condition at several q, by scans over the X-ray exit angle 3 (Fig. l(c)). These 

measuren~cnts are expectctl to reveal inforrr~ation about t,he length scales affcctiug 

surface excitatio~ls in the liql~itl metals. 

[I] ;\I. -1. Rcgm ct nl, Phys. Rfv. B 54 (1996) 9750. 

F@re 1. (a) Normalized X-ray reflectivity of liquid Hg at -X°C (D). -15°C (A). 

+6-C (0). and '23°C (0). Solid lines are model fits. (b) ;\lean-sq~~aretl surface 

roughness vs. temperature for liquid Ga antl Hg. Lines show the linear capillary 

wave dependence of a'(~) for estremal reported values of the surface tension. (c) 

Thermal diffuse scattering of liquid Hg at several values of q,. 

* 11.D. acknowledges support from the L-S-Israel Binational Science Foundation.

X-ray Scattering Studies of PBLG Monolayers at the Gas/Water 

Interface 

M. Fukuto, R.K. Heilmann, P.S. Pershan (Harvard U.), J.A. Griffiths, S.M. Yu, 

and D.A. Tirrell (U. Mass Amherst) 

We report x-ray reflectivity and grazing- incidence diffraction (GID) mea- 

surements of both mono-and polydisperse PBLG monolayers as a function of 

area/monomer A. We found no discernible effects on microscopic behavior due 

to differing dispersity. The area-pressure isotherm shows with decreasing A (I) a 

surface pressure free region at large A, followed by (11) a steep rise in surface pres- 

sure T, (111) a broad coexistence region with fairly constant -ir, and (IV) a further 

increase in -ir at even smaller A. The limiting values for A strongly suggest a mono- 

to-bilayer transition. In region (I) a single GID peak (inter-helix-distance d = 13.6 

A independent of A) indicates parallel alignment of a-helices. Together with reflec- 

tivity results and previously taken Brewster angle microscopy pictures this suggests 

coexistence of macroscopic areas of uncovered water with PBLG monolayer regions. 

In region (11) the subphase is completely covered by a monolayer and the GID peak 

shift shows a decrease in d to -- 12.6 A, resulting in an average in-plane compress- 

ibility of about 8 x lop3 cm/dyne in the direction perpendicular to the helix axes. 

In region (IV) the GID pattern shows a narrow (dl 2 12 - 12.6 A) and a broader 

peak (d2 2 13.5 - 14 A). Reflectivity indicates a bilayer with the top layer being less 

dense. These results suggest that compression through the coexistence region (111) 

forces a-helices out of the original monolayer into an initially unoccupied second 

layer on top. The compressibility of the sharp peak in region (IV) is comparable to 

that of the single peak in region (11), while the broader peak in region (IV) appears 

less compressible. We believe the broader peak originates from the less dense second 

layer. (Work supported by NSF-DMR-95-23440 and NSF-DMR-94-00396) 

Figure 1. top: dl and d2 vs. A; bottom: 

continuous -ir - A isotherm. 

Figure 2. Normalized reflectivities, fits 

and density profiles at three different A. 

X22B I Diffuse Scattering from a Langmuir Monolayer of PBLG* I X22B I 

M. Fukuto, R.K. Heilmann, O.G. Shpyrko, P.S. Pershan (Harvard U.), J.A. Grif- 

fiths, S.M. Yu, and D.A. Tirrell (U. Mass. Amherst) 

Off-specular diffuse scattering measurements have been carried out on the Lang- 

muir monolayer (LM) formed by polydisperse poly-y-benzyl-L-glutamate (PBLG) 

at the water/gas interface. The intensity is measured within the incident plane by 

scanning the detector angle (&scan) relative to the surface, for various fixed inci- 

dent angles (a). The results are shown in Fig. 1 for the monolayer at = 7.8 

dy/cm and in Fig. 2 for the bilayer at = 8.8 dy/cm. Each solid line corre- 

sponds to the convolution of the known experimental resolution with the differential 

cross section expected from the presence of thermally excited capillary waves and 

the surface structure used to model the reflectivity from the homogeneous Lang- 

muir surface layer. Agreement between the measurements and the theory for the 

PBLG monolayer supports the assumptions that the monolayer is microscopically 

homogeneous and the interfacial height fluctuations on the monolayer surface follow 

the capillary wave model. However, the data for the bilayer is consistently higher 

than would be expected for a homogeneous bilayer by a factor of 1.5 to 2. The 

ratio of the measured to the expected intensity is plotted in Fig. 2b for the bilayer, 

which clearly shows the excess scattering in the off-specular part. The understand- 

ing of the bilayer results requires further quantitative analysis. However, the excess 

scattering must be due to microscopic inhomogeneity in the second layer. 

*This work was supported by NSF-DMR-95-23440 and NSF-DMR-94-00396. 

PBLG rnonoloyer at T = 23 T, n - 7.8 dy/cm PBLG bilayer ot T = 23 'C, n - 8 8 dy/crn 

Figure 1. 0-scans for PBLG monolayer Figure 2. 0-scans for PBLG bilayer at 

at < -ir > = 7.8 dy/cm. < T > = 8.8 dy/cm.

I 

w 

z ( Surface Phases in Semifluorinated Alkane Melts * 1 X22B 1 

- - 

0. Gang (Bar-Ilan U., Israel), M. hIoller (Ulm U., Germany), B. Ocko(BNL), X.Z. 

Wu (IBhI Almaden), E. Sirota (Exxon) and hI. Deutsch (Bar-Ilan U.) 

The surface structure of melts of diblock n-alkanes F(CF2),(CH1),H (denoted 

F,H,) were investigated for n=12, 16, and 18, and m=12 near the bulk freezing 

temperature Tf. Unlike simple liquid. including non-fluorinated alkane melts, the 

X-ray reflectivity (XR) curves of the liquid surface (Fig. la) at -1OK above Tf show 

modulations for all three compounds, indicating layering at the surface. The shape 

and wavelength of the modulations are consistent with a first layer of molecules 

having its hydrocarbon part towards the vapour, and its fluorocarbon part pointing 

into the liquid. 

Upon cooling towards Tj. F12H12 ancl FLZHIR show surface freezing for 

Tj

Grazing Incidence X-ray Scattering Study of the Buried Glass-Liquid 

Crystal Interface * 1 X22B 1 

Y. Hu, T. K. Misra, and L. J. Martbnez-Miranda (U. of Maryland, College Park) 

We have used grazing incidence X-ray Diffraction to study the structure of a 

smectic liquid crystal (LC) film at the buried LC-glass substrate interface. This 

measurment is done in reflection mode through the glass substrate, which consists 

of a grating photolithographed onto a 0.22 mm glass slide. The experiment used 

both 1.38 and 1.34 A X-rays. X-rays in this energy range can penetrate through the 

glass substrate, which enables the direct study of the LC-glass interface. We varied 

the incidence angle between 0 and 0.5 degrees in order to obtain depth information 

on the the in-plane structure of the sample. Two grating depths were used in this 

study: 1.6 and 0.5 micrometers. 

Both the deep as well as the shallow gratings show evidence of in-plane alignment 

inside the grating grooves. The smectic layers exhibit a compression near the glass 

interface, as well as deep inside the film. The former result is consistent with 

previous reflectivity observations of confined LC's in similar gratings. The smectic 

layers are dilated at intermediate incidence angles. This structure is consistent 

with a chevron structure. In addition, the in-plane structure at the interface in the 

deeper gratings shows evidence of a higher azimuthal disordering than the structure 

observed in the shallow gratings. 

7d 

F 

m 

w * This work was supported by NSF Grant Nos. ECS-9530933 and ECS-96696069. 

I Charge Density Wave Structure in NbSes in High Magnetic Fields I X22B I 

V. Kiryukhin, D. Casa, B. Keimer (Princeton U.), J.P. Hill (BNL), M.J. Higgins, 

and S. Bhattacharya (NEC) 

NbSe3 undergoes two successive charge density wave (CDW) transitions at 145K 

and 59K. The magnetic field dependence of the charge density wave structure has 

been of interest since the discovery of a very large positive magnetoresistance below 

59K. On the basis of subsequent narrow band noise and thermopower measurements 

in transverse magnetic fields, it was attributed to a substantial increase in the num- 

ber of carriers participating in collective CDW transport, lowering the density of 

normal carriers in ungapped pockets of the Fermi surface. This would correspond 

to an increase in the CDW order parameter induced by the magnetic field. Theo- 

retically, this behavior can be understood by considering the orbital response of the 

electrons to the magnetic field. The transverse field constrains the electronic mo- 

tion, thereby improving the nesting properties of the quasi-one dimensional Fermi 

surface and enhancing its propensity for CDW formation. Other transport exper- 

iment seemed to suggest a magnetic field induced shift of the CDW wave vector. 

However, both some of the experiments and the theoretical interpretations were 

subsequently challenged. A microscopic, equilibrium probe such as x-ray diffrac- 

tion is necessary to conclusively establish the influence of a magnetic field on the 

amplitude and periodicity of the CDW. 

To this end, a NbSe3 crystal was mounted in a high field superconducting mag- 

net, and scans through superlattice reflections corresponding to the low temperature 

CDW were taken in a high resolution configuration. Typical data are shown in Fig- 

ure 1. An upper bound of A q/q < 2.5 x lop3 on the magnetic field induced shift 

of the CDW wave vector was thus established. The CDW order parameter is also 

magnetic field independent, to within 10%. These measurements complement trans- 

port data taken on the same material and help clarify a long-standing controversy 

regarding their interpretation. 

Charge Density Wave 

0.007 t I 

Figure 1. Scans through a CDW superlattice reflection in zero field, and at 1OT.

I The Surface Structure of Ferrocenyl Surfactants* I X22B I 

H. Kraack (Bar-Ilan U., Israel), V. Craig. N. Abbott (UC Davis), B. Ocko (BNL), 

X.Z. Wu (IBhI Almaden), and M. Deutsch (Bar-Ilan U.) 

Aqueous solutions of the surfactant (15-Ferrocenylpentadecy1)- trimethylammonium 

Bromide FeC15) show considerabe surface tension variations mith FeC15 

concentration (Q \ and oxidation state[l]. When oxidized, both ends of the molecule 

are hydrophilic. IVhen reduced, however. only one end is hydrophilic. It has been 

suggested. therefore, that a conformational transition occurs within the layer adsorbed 

at the surface. XVhen oxiclizecl a hairpin conformer was suggested. with both 

ends in the water. \Vhen reduced. the usual linear conformation is assumed. with 

only one end in the water, similar to insol~tblc Langmuir films. X-ray reflectivity 

(XR) measurernents were undertaken to test these suggestions. 

The XR of the retlucctl molecule shows only weak mod~llations for all h. The 

oxitlizetl ones, however. show strong modulations for n~etliurn and high O. Fits to 

the SR curves show a single (rnetlium-d) or two (high-d) high-tlcnsity layers at the 

surface. The lowest d shows no rrlotl~llations ard can be fit nit11 n slowly tlecrcasing 

tlrrisity profile. Figs. 1.2 slmw the rneasurctl XR ant1 t,he fit for thc high-(5 oxitlizetl 

state. 'These rcsl~lts may indicate surface-induced rnultilaycr ordering, with the 

n~lmber of layers i~~crrnsing mith d. Further :t~ialysis is in progress. 

'This work is supported by t,he Israel Science fount la ti or^, .Jerusalen~,(~I.D.) and 

the U.S. National Scicrice Fo'ountlation (N.A.). 

I. B.S. Gallartlo. K.L. hletcalfe, N.L. Abhott, Lnn,gm,uir 12. 4116 (1996). 

Figure 1. lleasured and fitted x-ray reflecti~-ity 

of 0.6mAI solution. oxidized. 

Figure 2. Surface density profile corre- 

sponding to the fit in Fig. 1. 

Structural Properties of Gramicidin A at the Air/Water Interface I X22B I 

H. Lavoie, C. Salese, D. Ducharme (U. of Quebec). D. Vaknin (Ames Lab), and 

B.M. Ocko (BNL) 

Valine gramicidin A (VGA) is a known antibiotic polypeptide consisting of fifteen 

amino acids with D- and -L alternate conformers, and forms specific ion channels 

for transport of monovalent cations through lipid membranes. The surface pressure 

isotherrn of gramicidin shows some features which are not yet well understood. In 

sit^^ X-ray reflectivity. X-ray GID and ellipsometry were used to characterize the 

film of gramicidin at the air-water interface. Fig. 1.4 shoxvs the surface pressure 

versus molecular area (r-A) isotherrn of VGX on pure water at 203C. Fig. 1B 

shows the thickness of the molecular film as a funct,ion of the molecular area. The 

thickness values were obtained, in sitt~ at the air-water interface. by X-ray reflectivity 

~neasuremcnts. Fig. 1B shows the phase shift 6A in an ellipsorltetric isother~n 

which depends on two parameters, the refractive index and the thickness. Usi~ig 

the thickness values from the reflectivity measwwrlerlts allowed determination of 

the refractive index of the film. which is shown as a clashed line in Fig. 1B. The 

grad~lal change in thc refractive index togctticr with the fact that the film thick~iess 

is smaller than any dinlension of the protein in its crystal form as a tlirncr, is a 

clear indication of intr;r-molecular rearr;tngcrner~t. possibly some degree of protein 

folding into the dimer tubular form. i\t lower rnolec~llar arms, (A < 300 :\"he 

refractive index is almost constant ant1 ttic increase in film tliickr~ess is th~c to the 

reorientation of the molcculcs with the pore of the tlirner facing the water interface. 

This is supported by t,hc CID st,~~tly of \'GA shown in Fig. 2B. Thr 2D Bragg 

reflection at Q,"!, = 0.45 is obsrrvctl only below molccl~lar area of 120 X"(7i % 

25 mN/rn, or abo~lt 240 :i2 per tlimer) aritl corresponds to the formation of a 2D 

crystallir~e 

phase with a Irexagonal lattice having a tl-spacirig unit cell of 16.09 .A. 

Figure 1. (-4) Lateral pressure. ellip 

sometric phase-shift. (B) film thickness. 

and refractive index. all versus molecular 

area of gramicitlin monolayer at the 

air-water interface. 

Figure 2. (-1) Sormalized reflectivity 

(R/RF) from 1-G.1 monolayer at the air- 

water interface at 2.3mS/m. (B) 2D- 

Bragg reflection from the same mono- 

la>-er corresponding to the ordering of 

densely packed tubular proteins.

In-Plane Depth Profile Studies of Strain in PZT and PLZT Thin 

-. 

X22B 

I Films " 

Yiqun Li, A. Dhote, S. Aggarwal, R. Ramesh, and L. J. Martinez-~iranda (U. of 

Maryland, College Park) 

We have performed initial depth dependent studies of the in-plane structure of 

PZT and PLZT thin films. These films were deposited on lanthanum aluminum 

oxide (LAO) substrates using the pulsed laser deposition method. Grazing incidence 

X-ray scattering was used to characterize the in-plane structure of the films, using 

1.554A X-rays. The observed in-plane peaks in PLZT consist of a strong signal 

superimposed on a difused background, as shown in Figure 1. This structure is 

a-axis oriented, and exhibits compressive stress along the direction of the substrate 

twinning lines as well as perpendicular to these. The stress along the latter direction 

is approximately twice as small than the observed stress along the the twinning lines. 

The in-plane structure of PZT consists of both a-axis and c-axis peaks over a difuuse 

background. The observed stress is smaller than in PLZT. 

PLZT (200) peak, ~n-plane scan, alpha = 0 

I I I I I I 

I I I I I I 

-23 -2 1 -19 -17 -15 -13 

phi [degl 

Figure 1. In-plane contour scan of the [200] region for PLZT in the direction 

perpendicular to the substrate twinning lines. 

w 

03 

c1 * Work supported through a NSF-MRSEC Grant No. DMR-9632521. 

rGy Reflectivity of Diblock Copolymer Monolayers at the 

Air/Water Interface 

X22B 

Z. Li, W. Zhao, J. Quinn, M.H. Rafailovich, J. Sokolov, (SUNY at Stony Brook), 

R.B. Lennox, A. Eisenberg (McGill U.), X.Z. Wu, M.W. Kim, S.K. Sinha (Exxon 

Research & Engineering Co.), and M. Tolan (U. of Kiel, Germany) 

PS2so-b-PVP-C,X240(X=I, Br; n-1,4,8,10) have recently been found to selfassemble 

at the air/water interface to form circular structures referred to as surface 

micelles. Synchrotron X-ray reflectivity studies were performed to address the structure 

relationship between Langmuir Films and the LB Films. Specular reflectance 

(see Figure 1) reveals that the thickness of the polyelectrolyte layer increases by 

a factor of 2 as polymer surface density increases Pfold. No significant hydration 

of the layer is observed. The off-specular scattering data (Figure 2) are well fit 

by an exact expression for the scattering intensity from a two-dimensional-ordered 

hexagonal lattice with a capillary wave contribution. The change in micelle-micelle 

distance or in the film thickness does not correlate in the pressure-area isotherm 

for 06. A correlation was observed onlv for the degree of surface ordering and the 

film stiffness. 

Figure 1. (left) The dashed line is specular reflectivity from the pure water surface. 

(right) The last curve was obtained after the film was decompressed.

I De~th-Dependence of Strains in Cu Films on A1N ' 

L. J. h~artinez-~iranda, Y. Li (U. of Maryland. College Park), L. K. Kurihara, P. 

Schoen, and G. h4. Chow (NRL) 

We have studied the depth dependence of the structure of Cu films deposited on 

AlN substrates via the polyol method. In this method, Cu particles are believed 

to precipitate from solution, ancl aggregate to form a number of reaction interfaces. 

and a nletallic film on the substrate. We have found that this metallic film consists 

of a bulk polycrystalline Cu film as well as an upper layer of (100) textured Cu. 

This laver constitntes as mnch as one third of the film. 

\Ve have studied the in-plane structure of this upper layer using 8keV X-rays. LVe 

have fo~mcl that the structure of the films in this region consists of a distribution of 

lattice spacings that correspond to strains that range between -0.G and 1 percent. 

as seen in Figure 1. The observed in-plane peaks are superimposed over a wide 

diffused background. The in-plane azimuthal texturing tlepentls on the time the 

solution is left refluxing during film processing as well as the orientation of the 

substrate during the deposition process. Films deposited on a horizontally oriented 

substrate are more textured than films deposited on a vertically oriented snbstrate. 

Films refluxed for a longer time are less textnred than those reflnxed at shorter 

times (compare Figures 1 and 2). 


Cu (200) peak of a 20 mi11 H sample at 


\York supported by SRL and OSR 

nanostructured materials programs. 




I X-Ray Reflectivity Studies of Alkanethiol Coated Gold Nanomrticles I X22B I 

B. Ocko and D. Nguyen (BNL), C. Clarke and B. Lennox (hIcgill U.), Z. Li (Exxon). 

hI. Rafailovich and J. Sokolov (SUNY at Stony Brook) 

Research in the area of "Nanophase hIaterialsn is largely motivated by the unique 

optical and electronic properties exhibited by the particles as a result of their finite 

size, shape, and packing configuration. X-ray reflection has been used to study the 

structure of Langmuir Films of alkanethiol coated gold nanoparticles deposited at 

the air-water interface. Using the results from this study ancl Transmission Elec- 

tron Microscopy (see figure 1) of Langmnir Blodgett Film studies, me are able to 

obtain information abont the molecular architecture (particle size. film thickness, 

and interparticle spacing) of films produced at different area/rnolecules, tempera- 

tnres. and using alkanethiols of varying carbon chain length. Preliminary resnlts 

indicate that the gold particles assume a prolate structure when spread on the water 

surface with a thickness of 20 angstronls. 

Figure 1. 

Interface. 

TEII micrograph of Gold -1lkanethiol Film lifted from the

-4 

I Electrodeposited Bromide on Ag(ll0); Phases and Phase Transition I X22B I 

B.M. Ocko and J.X. Wang (BNL), and T. Wandlowski (U. of Ulm & Munich) 

The structure of electrodeposition of Br on the Ag(ll0) surface from a NaBr 

solution has been investigated using surface x-ray diffraction techniques. As shown 

by the open circles in Fig. la, the primitive Ag(ll0) surface is rectanglar. Above a 

critical potential, -0.62 V vs. AgIAgC1 in 0.050 mM NaBr, the adsorbed Br forms 

an incommensurate c(px2) unit cell. As is typical of rectangular electrodeposited 

adlayers, the bromide adlayer is uniaxially electrocompressive. Diffraction scans 

through the lowest order peak, (H,0.5), are shown in Fig. lb. The peak position 

varies between 0.70 and 0.74 as the potential ranges between -0.60 and -0.20V1 

respectively. The bromide coverage is exactly equal to the peak position, thus it 

also varies between 0.70 and 0.74. 

Between -0.8 V and -0.62V no diffraction features, besides those from the Ag 

lattice are observed. However, above -0.80 V there is a large decrease in the scattered 

intensity at (0,1,0.1) as shown in Figure 2. This results from the adsorbed Br 

interferring destructively with the scattering from the underlying Ag lattice which 

occurs when the Br occupies the hollow rows, as indicated by the dashed lines in 

Figure 1. However, there is no concurrent loss of intensity at (1,0,0.1). This leads 

to the conclusion that the adsorbed bromide is a novel lattice gas one-dimensional 

liquid phase (see Figure la, left). 

Figure 1. (a) Left: Electrodeposited bro- 

mide in the one-dimensional lattice gas 

phase. Right: Electrodeposited bromide 

in the uniaxially incommensurate, (px2) 

phase. (b) Diffraction scans, (H, 0.5), in 

the (px2) phase. 

Figure 2. Potential dependent intensity 

at (1,0,0.1). 

I X-ray Reflectivity Studies of Phospholipids I X22B I 

A. Saxena, B. Ocko, D. Nguyen (BNL), C. Clarke (McGill U.), Z. Li (Exxon 

Research and Engineering), M. Rafailovich, J. Sokolov, and 0. Bahr (SUNY at 

Stony Brook). 

Its biological importance (almost half of the human cell membrane is composed 

of lipids) and its amphipathic nature makes phospholipids prime candidates for 

Langmuir-Blodgett Film type studies. The viscosity of the lipid is of biological im- 

portance because it is the controlling factor of most transport processes and enzyme 

activities. If the viscosity is too high transport processes will cease which may lead 

to cell dysfunctions. Phospholipids molecules have a hydrophilic head group and 

two hydrophobic tail groups (one saturated and the other unsaturated (contains 

a cis-double bond)). The difference in length of the fatty acid tails influence the 

manner in which the lipid molecules pack against each other, thus influencing the 

fluidity of the cell membrane. Lipid fluidity is a function of the temperature and 

composition. 

X-ray reflectivity was used to evaluate a Langmuir film of the phospholipid pre- 

pared at 25 C on a water surface (airlwater interface). The isotherm developed 

from this study is shown in figure 1. X-ray Reflectivity data for this study is shown 

in figure 2. The thickness increases with increasing surface tension and the thickness 

in the "solid" portion of the isotherm (5OmN/m) is 20 angstroms. 

Theoretically, the thickness of the layer that forms should not exceed 40 

angstroms which was proven in this initial study. More studies in the future will 

be directed towards varying the chemistry and the temperature of the trough bath 

in order to obtain biologically inportant information on the viscous properties of 

phospholipids.

P 

F 

CK 

XI 

In-sztu X-Reflectivity Measurement of Alkylthiolate Formation of Ag 

Ions and Alkythiol AImonolayer at the HnO/Air Interface 

K. TI-. Shin. AI. Rafailovich, J. Sokolov (SUNY at Stony Brook), Z. Li (Exxon 

Res.& Eng.). 4. Gibaud (U. du AIaine Faculte des Sciences, France), h1. I\'. Kim 

(KAIST, Korea) and Y.T. Kim (Yonsei U., Korea) 

The interfacial property between the sulfur(n-octaclecanethiol) and metal 

ions(Si1ver nitrate) has been studied by synchrotron X-ray reflection at the airwater 

interface using the Langmuir film balace technique. To understand the interfacial 

chemical and elecronic properties between the sulfur and metal atoms. the 

isolated metal alkythiolates were prepared. Our previous study of surface pressurearea 

isothernl measurements show the forrnation of alkanethiol Langmuir monolayer 

and the silver thiolates. The rrlorlolayers of n-octatlecanethiol are well ortleretl and 

tlensely packed( 20.~~nolecular area) at the water/air interface. At pressures where 

the thiol layer is highly ortleretl, me irlject silver nitrate solution into the water suhstrate. 

This subsequent rllonolayer forrrlation of silver thiolates was ~norlitoretl by 

in situ real-time X-ray measurements. After the AgN03 solution irljection. the X- 

ray reHect,ivity were lneasuretl repeatedly until the Xg ions cornpletecl the conlplex 

formation with the thiol group at the air/water interface. The reflection c1Irvc.s in 

Fig. 1 clearly show the process of the silwr thiolate forrnat,ion. 

From Figure 1, wc see that in the early st,agr there is no distinct change of the 

curves. \Ye found that the complete formation of ClXS-Ag rrql~iretl approxirnat,rly 

1 hour for the Ag ion diffusion, because silver nitmte solut,ion was i11,jectetl cnrefi~lly 

at the end of t,he trough to avoid the collapse of packed monol,2ver. The first, 

oscillat,ion(arrow in Figure 1) is becorning clrarly as t,irnc gors on. The rrs~llt was 

wrll ~natcllrd thr prrvio~~s resnlts of BXhI and cllipsornrtry cxpcrinlerlts. 

n-octadecanethiol and AgNO, in time dependence 

Figure 1. X-ray Reflectivity of Silver thiolate monolayer in time dependence. 

- 

X22B 

The Structure of Polyelectrolyte Block Copolymers in VTa- 

ter/Butanol Mixtures 

Block polyelectrolytes P(S260 - b- VPZJOIC~OB~) and P(S~~O-~-VPIIB/C.LI) have 

been found to self-assemble at air/water interface and to be surface micelles. Eisenberg 

et al. recently reported that there were three types of surface micelles of block 

polyelectrolytes, starfish surface micelles, partialy formed jellyfish surface micelles . 

and jellyfish surface micelles. Our previous studies found P(S260 - ~-VPZ-~O/CIOB~) 

at water surface formed only starfish surface rnicelles even under high pressure. due 

to high enerp compensation of such long hydrophobic hydrocarbon chains. To 

make a jellyfish snrface micelle, two scheme were suggested. 1) shortening the hydrocarbon 

chain length and 2) lowering the swface tension of water by actding 

l~utanol. In-situ synchrotron X-ray reflectivity meas~~rements wcrc performed to 

characterize the st,ruct,ure of swface ~nicelle forrnation of block polyrlectrolytcs at 

Langmnir-Blotlgett trough. 

The conformational change of surface ~nicelles occurs if there is rnough prcssllre 

on the surface micelles induced by barriers of LB trough. The corlforrnation of 

rnicrlles depends on the corona-cororm interaction of neighboring nliccllcs lowering 

thc surfacr enrrgy. The large s~~rfacc tension of water prevent thc polymer chain 

from ent,cring thc subphase. Therefore, adding n certain arnol~nt of 1)utnnol lcsscr~s 

thc sl~rface tension of the air/watrr intrrfacr and thr coronas of micc~llrs co~~ltl 

tlitfilsc morr rasily into the water phasr. Dnr to t,hc rc.1ativcly high clcctron tlcusity 

of ionic grollp. X-ray reflrctivity rxprrirncnts arr scnsitivc to tllc. ion tlistrih~~tiou 

nrar the s~~rfacr. The oscillations which arc clrarly visiblr in pllre water (Fig. la) 

tlisnppcar whrn b~~tnnol is atltlrtl(Fig. lb) intlicnting that the polyn~cr t1wc fornlctl 

,-< 

PS,,,P~V(C,B~)~~, in Water 

PS,,,P4V(C,Br),l, in Butanol 3.30h 

X22B 

K. \\-.Shin. AI. Rafailovich, J. Sokolov (SUNY at Stony Brook), D. Nguyen (BNL). 

Z. Li (Exxon Res. & Eng.). A. Gibaud, G. Vignaud (U. du Maine Faculte des 

Sciences), J. Cox. and 4. Eisenberg (AIcGill U.. Canada) 

Figure 1. Figure 2.

Magnetic and Structural Measurements of Substrate-Matched Er- 

X22C 

bium Films 

G. Helgesen (IFE, Norway), D. Gibbs (BNL), M.J. Conover, and C.P. Flynn (U. 

of Illinois) 

The magnetic and structural properties of three erbium films epitaxially grown 

on a LU~.~YO.~ alloy substrate have been studied using x-ray magnetic resonant 

scattering at the Er LIII edge. The composition of the substrates was chosen in 

order to minimize the strain at the Er-substrate interface. The epitaxial relationships 

in two of the samples were [I101 A1203 11 [110] Ta (1 [001] L~0.6Y0.4 11 [001] Er. 

Their Er film thicknesses were 4000 Aand 1000 A. A third sample with thickness 

4000 Ahaving a [001] A1203 substrate base layer was also studied. Although the 

average Er lattice constants of these films were closer to those of bulk Er than those 

of Er on Y substrates studied earlier, their magnetic behavior for temperatures below 

55 K showed clear deviations from that of bulk Er. The conical 5/21 phase 

found in bulk samples was suppressed in these thin films. At low temperatures 

the magnetic wave vectors of the 4000 Afi~ms locked to 114 and 4/15 for [I101 and 

[001] sapphire substrates, respectively. It seems that even for thin film samples 

with minimal film-substrate interfacial strain the interfacial clamping is sufficient 

to alter the low-temperature magnetic structure. 

A A A AA 

4 

Temperature [K] 

film #l , cooling 

0 film #l, heating 

A film #3, heating 

Figure I. Magnetic wave vector of Er as a function of temperature. 

Incommensurate Magnetism In I X22C I 

J.P. Hill (BNL), A.T. Boothroyd (U. Oxford), N.H. Andersen (Risoe), E. Brecht 

and T. Wolf (Forschungszentrum Karlsruhe) 

One strategy for elucidating the mechanism of high temperature superconductivity 

is to study compounds in which the superconductivity is anomalously suppressed. 

The absence of superconductivity in Laz-,BaxCu04 for example, has been found 

to be associated with the pinning of incommensurate charge and spin stripe correlations, 

which may form the basis for a pairing mechanism in the cuprate superconductors. 

Similarly, PrBa2Cu3Ofi+, has attracted a great deal of interest as an anomalous 

member of the (RE)BU~CU~O~+~ series, where RE=rare-earth. In addition to 

the absence of superconductivity, a number of other magneto-transport properties 

are unique; it is an insulator, exhibiting Cu antiferromagnetism for all x, and the Pr 

sublattice appears to order at unexpectedly high temperatures, TP,(x) = 10 - 20 K 

, compared to other members of the series, for which TRE = 0 - 2 K. This behavior 

is particularly puzzling in light of the fact that the hole densities in the CuO planes 

and chains are very similar to superconducting members of the series. 

The role of the Pr site magnetism in these phenomena remains an open question. 

While neutron scattering studies suggest that the Pr does indeed carry an 

ordered moment, this interpretation has been called into question by recent NMR 

work, which suggested that the ordered moment was only 0.017 p ~ TO . address 

this issue we have carried out resonant magnetic x-ray scattering studies of this 

compound. This technique has the advantage that it is element specific, and offers 

high reciprocal space resolution. The primary result of this work is shown in the 

figure below, in which a scan through the (0.5,0.5,8) antiferromagnetic Bragg point 

is shown. These data were taken with the incident energy tuned to the Pr LII edge 

and thus demonstrate the existence of an ordered Pr moment. Remarkably the Pr 

magnetism was discovered to be incommensurate, as illustrated by the existence of 

two magnetic satellites. The neutron data confirm this result and prove that the 

modulation is a static one. 

l?.?.Il scons 

Figure 1.

w 

c3 

X-Ray Resonant Exchange Scattering Studies of Magnetic Struc- 

tures of EuNi2Ge2 Single Crystal in Zero Applied Magnetic Field 

X22C 

Z. Islam, C. Detlefs*. A.I. Golclman. S.L. Bud'kot. P.C. Canfield (Ames Lab.), J.P. 

Hill and D. Gibbs (BNL) 

Afagnetic structures of EuNilGel (I4/mmm) single crystal was studied using 

XRES technique at Eu LII edge (El-resonance). Due to high absorption of new 

trons by Eu and small size of these crystals conventional neutron scattering is not 

feasible. From rneasuren~ents of bulk magnetization (carried out at Xmcs Lab.) two 

transitions were seen (T.v s34K and Tt s14K). Paramagnetic moment was found 

to be consistent with EU+~ ground state (4S7/2). Since there is no orbital moment 

in this state (as in Gcl'" no CEF effects are expected in first approximation; the 

anisotropy observed in t,his material then originates from anisotropic RKKY exchange 

interaction. So. the study of magnetic struct~~rc provides insight into pure 

exchange effects in this compo~md. 

This compound orders antiferrornagneticdly with wn7e vector F,,, = (001) below 

T.Y. 7,,, remains the same as the ternperatwe is lolvcrrd through Tt. Prelirninary 

measl~re~ner~ts of the Q-tlepentlence of a series of rnagnrtic pmks at 24K suggests 

a I;trgc En rno~ner~t component in the hasal plane w11rrt:ns at :

Surface Relaxation on the Clean and Hydrogen Covered Ru(001) 

Surface Measured By X-ray Diffraction 

V.Jahns, A.P.Baddorf, D.M.Zehner (ORNL), and D.Gibbs (BNL) 

In several previous LEED investigations of the clean Ru(001) surface a 2% con- 

traction of the top layer distance has been determined. On the Hydrogen-covered 

Ru(001) surface the contraction is removed and even a slight expansion occurs (1- 

2%). On the other hand, theoretical geometrical structure studies predict a much 

stronger layer contraction of 4% for the clean Ru(001) surface and also a contrac- 

tion of 1.5% for the Hydrogen-covered Ru(001). Motivated by the currently ongoing 

controversy we have measured the X-ray diffraction intensities of the specular and 

off-specular truncation rods of the clean and Hydrogen-covered Ru(001) surface for 

temperatures from 300K up to over 2000K. It is observed that the truncation rod 

intensities for the clean Ru(001)-surface at room temperature and 500K and for 

the Hydrogen-covered surface at room temperature are not significantly different. 

Under these conditions the intensity distributions clearly indicate a contraction of 

the top layer distance. At temperatures of 1890K or 2040K we observe a small 

change in the modulation of the truncation rod intensities with respect to the low 

temperature data which can be attributed to a partial release of the contraction. 

Keeping the momentum transfer fixed at the off-specular truncation rod (Q = 1 0 

1) and changing the temperature it is observed that at high temperatures far below 

the melting point the intensity decrease obeys Debye-Waller behaviour. At highest 

temperatures close to the melting point a strong decrease of the truncation rod 

intensity might indicate anharrnonic thermal effects. 

OOL CTR Ru(OO1) clean surface 

100000 Y 

# 1 

[r.l.u.] 

Figure 1. Speculare reflecivity of Ru at different T. 

X22C 

I Structure and Phase Behavior of Ir(001) I X22C I 

V. Jahns, D. M. Zehner (ORNL), G. Watson (UMBC, BNL) and D. Gibbs (BNL) 

The structure and phase behavior of the Au(001) surface between room temper- 

ature and bulk melting is remarkably similar to that of Pt(001). For example, both 

surfaces exhibit disordered phases at high temperatures (above 0.9 Tm, where Tm 

is the bulk melting temperature) and incommensurate quasi-hexagonal reconstruc- 

tions at lower temperatures. In addition, for temperatures decreasing below about 

0.8 Tm, both exhibit surface rotational transitions. However, there are also intrigu- 

ing differences. The high temperature disordered phase of Pt(001) is rough, while 

that of Au(001) appears smooth, although disordered within the surface plane. The 

Pt(001) surface further exhibits a continuous rotational transformation while that 

of Au(001) is discontinuous. Although some progress has been made in describing 

the phase behavior of Au(001) using MD simulations and modified elastic theory, 

these fascinating differences between Pt and Au remain largely unexplained. In the 

present work, we have undertaken an x-ray scattering study of the structure and 

phase behavior of Ir(001), the neighbor to the left of Pt in the Periodic Table. We 

find that at temperatures above 0.7 Tm, Ir(001) apparently roughens in a manner 

similar to Pt(001) (see Figure 1). Below 0.7 Tm, the surface exhibits a corrugated, 

quasi-hexagonal reconstruction (see Figure 2), similar to that of Au and Pt (001). 

However, in constrast to Au and Pt(001), the Ir (001) reconstruction is commen- 

surate with the substrate (possessing a simple (5x1) structure) and exhibits no 

rotational transformation at any temperature. The absence of a rotational trans- 

formation is qualitatively consistent with the theory of Novaco and McTague, who 

showed that an incommensurate overlayer on a rigid substrate can lower its energy 

by a small rotation. However, their theory fails to predict the rotation angles ob- 

served for Au and Pt (001). In summary, the structures and phases exhibited by Ir, 

Pt and Au(001) surfaces are qualitatively very similar, yet differ strikingly in their 

details-in ways which stand outside the predictions of any current theories. 

I. 

A 

-0.04 Q, -0.02 [UNITS 0.00 OF c'] 0.02 

Figure 1. Transverse profiles of the spec- 

ular reflectivity of Ir (001) at L=l.Oc* 

taken at T=690 K and 2000 K, respec- 

tively. 

0.04 

L [R.L.U.] 

Figure 2. Integrated specular reflectivity 

profiles taken at T=690 K and 2052 K.

F 

CD 

P\3 

hlagnetic Structures and Phase Transitions of U(As1-,Se,) Solid 

Solutions 

h'1.J. Lon~eld, W.G. Stirling (U. of Liverpool, UK), E. Lidstrom (ESRF, France 

& EITU. Germany) and G.H. Lander (EITU, Germany) 

Continuing our study of actinide antiferromagnets, we have used the X22C instrument 

to probe the magnetic structures of U(As1-,Se,) solid solutions with x=0.1, 

0.2 and 0.22, at the uranium i\Irl- edge. On cooling, these materials order into 

incommensurate phases and then undergo first order transitions to a commensurate 

phase with a multi-q wavevector which depends upon the selenium concentration 

1.1 

Ill. 

We have observed an extra periodicity of the triple-q structure for the x=0.2 

sample which has a modulation wavevector, q,,,, -0.44 r.1.u. At low temperature. 

we have found the x=0.22 crystal to have a similar magnetic structure. The extra 

modulation for x=0.22 is much weaker than for the x=0.2 sample and does not exist 

for either the x=0.1 or 0.4 compositions (which do not have the triple-q structnrc). 

Figure 1 sho~vs the formation of the additional magnetic modulation in the commensurate 

phase of the x=0.2 crystal. By developing the spin-slip description of 

CeSb [2] we have arrived at a possible model for the extra periodicity, qrrr=qo(ll/b)=O.444. 

The modulation is described as fraction of the con~n~ensurate magnetic 

wavevector, qo=0.5, which is determined by the mlrnber of atomic planes separating 

the atltlitional spins (b=9 in this case). The additional motlulation of the triple-rl 

structure may be an effect confined to the near surface layers, but as yet we have 

no conclusive evidence of this. 

The critical scattering heshape (above T.v) for the x=O.l sample is very broad 

in the specular direction. The transverse direction (H) renlains relatively sharp for 

the (0. 0, 2+q) incommens~~ratc motll~lation, which is shown in Figure 2. This 

scattering is fitted to a single Lorentzinu fimction. It is not obvior~s that there 

is any significant sharp co~nponent arising frorri a second length-scale [3,4] in this 

material. 

[I] Kuznietz et al .T. hi. ;\I. hI. 69 12 (1987); [2] hIchIorrow et a1 J. Phys. Condens. 

hIatter 9 1133 (1997); [3] Perry et al Phys. Rev. B54 15234 (1996): [4] i\ltarclli ct 

al Phys. Rev. Lett. 74 3840 (1995). 

Figure 1. The extra periodicity of 

the triple-q magnetic structure. for the 

x=0.2 sample. 

X22C 

Figure 2. Transverse critical scattering 

from the x=0.1 sample. near T.y-120K. 

I Orbital Ordering in a Cubic Perovskite I X22C I 

Y. hlurakami, I. Koyama, M. Tanaka (KEK), J.P. Hill, D. Gibbs and ill. Blume 

(BNL) 

There is a great deal of current interest in strongly correlated electron systems, 

such as the transition metal oxides, which exhibit such diverse phenomena as high- 

Tc superconductivity and colossal magnetoresistance. The rich physics of these 

systems results from the fact that the charge, spin and orbital degrees of freedom 

all play important roles in determining the electronic and magnetic properties. Of 

these phenomena, the least well understood is the behavior of the orbital degrees of 

freedom. This is because. until recently, there has been no direct probe of orbital 

order. though its presence has been inferred indirectly from, for example, lattice 

clistortions associated with cooperative orclering. 

X-ray scattering is sensitive to the charge distribution in a solid, and therefore is, 

in principle, capable of observing orbital ordering directly. However, the sensitivity 

to the anisotropy in the charge distribution res~~lting from just one orbital out of 

the total complement of a given ion is very small. Fortunately, this situation is 

altered by tuning the incident photon energy to a resonance that couples to that 

orbital. In this case, the sensitivity may be dramatically cnhancetl. 

iVe have carried out studies of LahInOs. Resonant scattering mas observed with 

the incident photon enerD tu~led to the vicinity of the hIn K-edge, corresponding 

to a doubling of the periodicity along the (110) tlirectiori. We attribute this to an 

ordering of the h1n3+ e, orbital. This interpretation is supported by the polarization 

tleperitlence of the scattering, which is dominantly a -+ T, and the azimuthal 

tleperitlence, which shows a twufoltl symmttry for rotations about the scattering 

vector. Theoretical calculations tlcscribing the scattering process and which prrtlict 

these depentlences are currrntly ~~ntlerway. The temperature dependence of the 

orbital ordering was also i~lvcstigatctl. The orclering mas found to disappear above 

To x 820 K, coincidrnt with an orthorhombic to rhornbohetlral strucutral phase 

transition.

!d 

F 

c 

I Structure and Magnetism of EuB6 * I X22C I 

S. Siillow, M.C. Aronson (U. of Michigan), J.L. Sarrao, Z. Fisk (NHMFL), A. 

Vigliante, and D. Gibbs (BNL) 

Recent experiments on EuB~ single crystals (Pm3m) show the system to undergo 

two instead of the previously reported single ferromagnetic transition. However, 

the appearance of two FM transitions in a cubic m3m crystal is impossible because 

of severe symmetry restrictions on the possible magnetic structures for a given 

crystalline symmetry. Thus, to determine the symmetry of our crystal we performed 

a detailed x-ray study. In Fig. la we present the T dependence of the lattice 

parameter a of EuB6, determined from the [loo] and [200] Bragg peaks. The overall 

value of a agrees well with previous reports. At the magnetic transitions no change 

of the lattice parameter is seen, ruling out massive structural changes accompanying 

the transitions. In Fig. lb we plot the intensity distribution in one quadrant of 

reciprocal space [hod close to the [300] Bragg peak at 20K; similar results have been 

found at other Bragg peaks. The intensity distribution of the Bragg peaks is not 

isotropic in the hl plane. Instead, wings protrude from the side of the Bragg peak. 

The intensity distribution of the Bragg peaks themselves was well-described by 

a resolution-limited Lorentzian function, corresponding to a structural correlation 

length of 24000A. The wings at the Bragg peaks are found in all hkl planes, with 

one wing for each quadrant of the plane. The direction of the wings in [hkl] space 

is not related to a high symmetry axis of the lattice; for instance, the relative 

direction of the wing in Fig. lb is [-3021. The wing intensity decreases slightly 

as T is increased from 10 to 150K, making thermal diffusive scattering unlikely. 

Several other explanations for the wings, like strain, lattice disorder or vacancies, 

are possible, but presently we cannot determine which of these apply to EuBs. 

Regarding the symmetry of our crystal, we found a structural anomaly, but cannot 

conclusively relate this to a lowered crystalline symmetry. 

Figure 1. 

* Work at U.of Michigan was supported by DOE, Grant 94-ER-45526, and at BNL 

under contract No. DE AC0276CH00016. 

I Real-time Relaxation of the Cu/Ru(001) Interface During ~rowtk-1 X22C 1 

H. Zajonz, D. Gibbs, (BNL), V. Jahns, A.P. Baddorf and D.M. Zehner (ORNL) 

Since the discovery of the stripe-phase reconstruction of An(lll), in which par- 

tial dislocations separate regions of fcc stacking from hcp stacking, this motif has 

been found in nearly all heteroepitaxial metal systems studied to date. However, 

very little is known about the structure of the interface. In this work, we have 

begun x-ray scattering studies of the structure of Cu layers deposited on Ru(001) 

substrates during growth and versus substrate temperatnre. The near-neighbor 

spacing in bulk Cu is 5.8% smaller than that of Ru, which has an hcp structure. 

From earlier STM studies, it has been established that the first layer of Cu on Ru 

adopts a pseudomorphic structure, but that the two-layer film exhibits a stripe- 

phase reconstruction. Our x-ray experiments involve characterizing the appearance 

and evolution of the stripe-phase reconstruction peak as a function of Cu coverage 

and substrate temperatnre. At 720 K, we confirm a pseudomorphic Cu structure 

for coverages up to about one monolayer, followed by the growth of a stripe-phase 

reconstruction between one and two layers (see Figure 2). We find that the av- 

erage Cu spacing is contracted in the stripe-phase by about 5.3% relative to the 

near-neighbor spacing of the Ru(001) substrate. At two monolayers coverage, there 

is an abrupt contraction of the average Cu spacing by an additional 0.5% (see 

Figure 1). Remarkably, the interfacial lattice then appears to oscillate with a 0.1% 

amplitude and a three layer period at least for coverages up to ten monolayers. To 

our knowledge, this phenomenon has not been observed previously for an interfacial 

reconstruction. Preliminary studies at lower temperatures (300-500 K) suggest that 

the stripe-phase, interfacial reconstruction is relatively disordered, and that at some 

temperature there is a cross-over to the ordered, oscillatory behavior. However, this 

remains to be established. 

Cu-coverage [ML] 

Figure 1. Stripe-phase peak position 

in reciprocal space versus coverage of 

Rn(001) by Cu in monolayers (ML). The 

abrupt change at two monolayers corre- 

sponds to a contraction of the average 

Cu lattice constant of about 0.5%. 

Figure 2. Inplane diffraction pat- 

tern of the Cu/Ru(001) interface for 

10 monolayers Cu coverage at 720 K. 

The intense peak located at (H,K)=(l,O) 

corresponds to the (1,0,0.15) trunca- 

tion rod of Ru 001). The peak at 

(H,K)=(1.02,0.04\ is the first harmonic 

of the stripe-phase reconstruction of the 

Cn. The second harmonic is visible at 

(H,K)=(1.06,0.06).

P 

F 

o 

A 

In situ X-ray Absorption Studies of Electrodeposited Thin Films * I X23A2 

h1. Balasubramanian and C. A. Melendres (ANL) 

We have performed in situ x-ray absorption studies on electrodeposited films of 

Ni and Cr from aqueous solutions and determined the local atomic and electronic 

structure of these elements in such films. The films mere deposited on a graphite 

substrate, typically at a constant cathodic current of 5.1 mA/cm2 for 15 minutes. 

As can be seen from the XANES, illustrated in Figure (I), the films deposited from 

solutions containing Cr+%ons do not show a significant pre-edge feature, consistent 

with the presence of Cri"n such films (curves a and c). A film formed from a 

solution containing Cr+"ons shows only a small pre-edge feature. suggesting Cr 

exists pretlominantely as Cr+"in this film (curve b). In sharp contrast. the film codeposited 

from a solution containing Cr'' and ions, snprisingly shows a large 

pre-edge feature, clearly indicating that Cr in this film exists almost exclusively as 

Cr+"curve tl). \Ve have performed a systematic study of s11ch films to l~ntlerstantl 

the effect of oxygen by using tleaerated solutions as well as by exposing these films 

to air antl measuring them ex-situ. Detailed results will be reported in future. 

These investigations are of interest in various fields s11c11 as electrocl~rornic devices, 

batteries. corrosior~, environmental rer~lctliation, etc. 

Figure 1. In-sztu Cr X-AXES of cathodically deposited films from aqueous solutions: 

(a) 0.0111 Cr(S03)3. (b) 0.0111 K2Cr01. (c) 0.111 Si(S03)2+0.0111 Cr(NO3)3. (d) 

0.111 Si(X03)2+ 0.00111 K2Cr04. 

Research supported by the C.S. DOE under contract \V-31-109-ESG-38. 

Processing of Pure-Phase hInZn-Ferrite Using High-Energy Ball ~ 2 3 ~ . 

Milling: An X-Ray Absorption Fine Structure Study 1 X23A2 1 

D.J. Fatemi, V.G. Harris(NRL), and J.P. Kirkland(SFA) 

hIn.jZn.jFe204 ferrites were processed by mechanical alloying a mixture of the 

elemental oxides hInO, ZnO, and Fez03 in a high-energy shaker mill. The structure 

of the milled mixtures was studied via X-ray diffraction (XRD) and extended 

X-ray absorption fine structure (EXAFS) measurements. Broad diffraction peaks. 

corresponding with those of the spinel ferrite phase, mere detected via XRD after 

180 min. of milling (the sample of shortest milling duration). whereupon a pure 

phase spinel ferrite (as judged by XRD) was measured in the 1260 min. millecl 

sample. The atomic fraction of metal ions existing in the ABzO't-type structure. 

where A antl B refer to tetrahedral and octahedral coorclinatetl cations, was rrreasuretl 

as a function of milling duration by EXAFS. This arlalysis reveals that the 

conversion of n~etal ions from their elenicntnl oxide structwes to the spinel phase 

occurs near-linear with milling time with 50% of the oxides corivertctl after approximately 

500 minutes. hIultiple-scatterirlg EXAFS modeling was applied to measure 

the site distribution of the various cations as a function of rrlillir~g time. Compared 

with an equilibrium XIn.aZn.r,Fe20.1 powder sample, which was prcparetl by tratlitional 

fire and grinding techniques. the mechanically alloyed ferrite samples exhibit 

a higher fraction of Fc antl hIn cations on thc A-sl~blatt,ice. while an ~lnllsually high 

popl~lation of Zn cations resides on the B-sublattice. The site tlistrib~~tion can he 

infwrcd qualitatively from Fig. 1, in which pcaks laheled i\ a11t1 B arise largely 

from occ~lpatiorl of the absorbing atom on A-sitm and B-sites, respectively. 

Radial Coordinate (A) 

Figure 1. Fourier transformed (a)Fe. (b)1In. and (c)Zn EX-IFS data from SInZn- 

ferrite formed after 10 hrs of milling and from the stantlarcl.

U1 

NEXAFS Studies of Ru in the Ternary Skudderudite 1 X23A2 1 

V.G. Harris (NRL), G.S. Nolas (Marlow Industries), G.A. Slack (RPI), and T.M. 

Tritt (Clemson U.) 

When the atomic species under consideration exists in a multiple of valence states, 

the near-edge region of the absorption spectrum will be a superposition of the 

multiple absorption transitions. In order to measure multiple valence states in 

a sample of unknown valence one typically makes use of empirical standards of 

known valence. In the case of the ternary skutterrudite, Ru~,sPdo.~Sbs, standards 

of RuSb2 and RuTe2 were employed. These standards where selected because the 

Ru ions are 4+ and 2+, in RuSbz and RuTez, respectively. These prove valuable in 

'fingerprinting' the RU~+ and Ru2+ valence states in the ternary skutterudite. The 

first peak in the derivative spectrum corresponds to the inflection point occurring 

at approximately 50% of the absorption edge step, and is used here to identify 

the onset of absorption, Eo. This peak is fit using a Gaussian curve to accurately 

measure Eo and the half-width at half-maximum (HWHM). Figure 1 is a plot of the 

isolated first peak data of the derivative versus photon energy for the skutterudite 

and the two standards. The best fit curves are presented as solid lines and the raw 

data as symbols. 

To accurately measure the relative fraction of the Ru ions we fit the skutterudite 

data with the best fit Gaussian curves of the standards where the only adjustable 

parameters are the amplitude of the standards' curve?. The relative fraction of 

the valence states is then given by the ratio of the best fit amplitudes. Using this 

method we calculate the valence of the Ru in the skutterudite to be 3.1+, or if one 

were to assume that Ru exists only as 4+ and 2+, 52% of the Ru would be 4+ and 

48% is 2+. 


Figure 1. Isolated first peak data from the derivative of the Ru NEXAFS with best 

fits determined by least-squares fitting using Gaussian curves. Markers indicate the 

curves centroid. The data corresponding with the R~~.~Pdo.sSbs sample was fit 

using a combination of best fit curves from the standards. 

XAS Studies of Preferential Site Distribution of Ta and Pt in CoCr- X23A2, 

Based Films* 

X23B 

K. M. Kemner (ANL), V. G. Harris, W. T. Elam (NRL), Y. C. Feng, D. E. Laughlin 

(CMU), J. C. Woicik (NIST), and J. C. Lodder (Mesa Research Institute) 

CoCr-based alloy films are presently the mainstay mangetic recording media. 

Numerous studies have shown that these films can be grown in ways to produce a 

compositional inhomogeneous microstructure having Co- and Cr-enriched regions. 

The addition of Ta, Pt to these media play an important role in determining the 

magnetic properties and recording characteristics of the films. In order to better 

understand the beneficial roles of their addition, we have made XAS measurements 

on a variety of CoCrX (X=Ta or Pt) films deposited at ambient and 260 C substrate 

temperatures. Analysis of the Ta and Pt data indicates that no phase separation 

of the Pt or Ta atoms into clusters has taken place. Further analysis shows that for 

an increase in substrate deposition temperature, the average coordination number 

decreases by 0.6 Co/Cr atoms. Figure 2 shows that, with the addition of Ta and 

Pt, the Fourier peak amplitudes of the Co EXAFS data decrease relative to that of 

the data for a pure CoCr film. The greater reduction in amplitude of the Fourier 

peaks when Pt is added than when Ta is added indicates that the Co environment 

is more disordered by the addition of Pt than by the addition of Ta, suggesting a 

preferential site distribution of the Pt atoms to the Co atoms. "KMK was supported 

by a National Res. Council/NRL Fellowship. Research also supported by the U.S. 

DOE, Office of Basic Energy Sci. & Office of Health & Environmental Res., contract 

No. W-31-109-Eng-38. 



Figure 1. Fourier transformed Ta and Figure 2. Fourier transforms of Co 

Pt EXAFS data for the CoCrX (X=Ta EXAFS data for the CoCrX (X=Ta or 

or Pt) samples deposited at ambient and pt) samples deposited at ambient and 

260°C substrate temperatures. 260" C.

w 

c3 

XAFS Studies of the Aging of Soils Contaminated With Ethylene 

Dibromide* 

K. hl. Kemner and S. T. Pratt (ANL) 

One of the fundamental issues in environmental remediation and management 

concerns the time dependence of the bioavailability of toxic chemicals in soils. For 

many chemicals, this bioavailability decreases dramatically with time, even though 

destructive analysis of the soil indicates that the chemicals are still present and 

remain intact; that is, in the times immediately following the application to the 

soil. the chemical appears to be readily available for degradation, although at much 

later times, the remaining chemical is essentially unavailable for uptake by microor- 

ganisms, fungi, and plants. 

Halogenated hydrocarbons make up one of the largest classes of contaminants 

found in both military and civilian hazardous waste sites, ancl these solvents have 

created some of the greatest problems in terms of contaminated drinking water. 

Bronlinatetl hydrocarbons such as ethylene tlibromide, which has been used exten- 

sively as a fungicide in agriculture, also represent a substantial problem. 

One hypothesis for the process responsible for the aging of chemicals in soils is 

that the cllerrricals are eventually sequestered in the hydrophobic organic matter 

within the soil, and another hypothcsis suggests that the aging is clue to the entrap 

ment of the chemicals in rnicroporcs of the soil that are too srrlall to allow access by 

bacteria. Both proposed rnectianisms for the aging of chemicals in soils are based 

on the hypothesis that changes in the binding or sorption sites of the chemical are 

responsible for changes in the bioavailability. Lye have been investigating the util- 

ity of using ?

I Structure and Chemistry of FeS2 Battery Cathodes * 

X23A2, 

VQ9D 

E. Strauss, D. Golodnitsky, E. Peled (Tel Aviv U.) S. Kostov, M. L. denBoer, and 

S. G. Greenbaum (CUNY, Hunter College) 

The Li/CPE/FeS2 battery (CPE = composite polymer electrolyte) is a promising 

candidate for energy storage and electric vehicle applications. Its projected specific 

energy is over 170 Wh/kg (based on 2.5 e/FeS2), and a recent small laboratory cell 

demonstrated over 300 full charge-discharge cycles. Using in situ x-ray absorption 

methods we have investigated the behavior of thin Li/CPE/FeS2 cells at various 

stages of charge and discharge cycles. Cells were examined under the following 

conditions: (i) charged to 1.85 V and x = 0.5, where x represents the number of 

electrons associated with that particular charge state; (ii) charged to 2.05 V and x 

= 1.7; (iii) charged to 2.25 V and x = 2.0; (iv) discharged to 1.65 V and x = 1.4; 

(v) discharged to 1.25 V and x = 0.15, and (vi) discharged to 1.1 V and x = 0.0. 

Regardless of whether the cell is being charged or discharged, there appear to be only 

two distinct Fe host environments, a "low-Li" one for conditions (ii), (iii) and (iv) 

and a dramatically different "high-Li" one for conditions (i), (v) and (vi). At high 

Li (cathode) concentration a strong pre-edge feature is apparent, which decreases at 

low Li concentration, as shown in Fig. 1.. This pre-edge feature is dipole-forbidden 

in octahedral symmetry, and its decrease therefore indicates that the symmetry 

decreases as Li is removed from the cathode. The EXAFS similarly falls into two 

distinct categories (Fig. 2). At high Li concentration the Fe environment is ordered, 

and analysis reveals a combination of metallic Fe and residual unreacted FeS2. On 

the other hand, at low Li disorder sets in and only a single broad peak is observed, 

analysis of which indicates a combination of FeS2 and LizFeSz. Structural and 

chemical changes in the Fe environment appear to be highly reversible. 


- YJ w 

C3 

4 

Figure 1. Near-edge x-ray absorption 

spectrum of cells under various charne 

conditions as described in the text. 

" Supported by DOE Basic Energy 

Sciences 

Spacing (Angstroms) 

Fieure 2. Fourier transform am~litude of 

reGresentative low-Li and hig6-~i cathodes. 

I Phase-correct Bond Lengths in Crystalline GeSi Alloys I X23A2 1 

J.C. Woicik (NIST), K.E. Miyano (Brooklyn College), C.A. King and R.W. Johnson 

(Lucent), J.G. Pellegrino (NIST), T.-L. Lee (Northwestern), Z.H. Lu (NRC) 

Extended x-ray absorption fine structure performed at the Ge-K edge has deter- 

mined the Ge-Ge and Ge-Si bond lengths in a series of crystalline GexSil-x alloys 

(xi0.5) to be compositional dependent. This high-accuracy measurement was made 

possible by utilizing the experimentally determined Ge-Si atomic phase shift from 

the isoelectronic compounds AlAs and Gap. Strain and Coulomb contributions to 

the bond lengths are also considered.

tj 

F 

c3 

CO 

The Relationship Between RIicrostructure Development in Hyclrat- 

ing Cement ancl the Morphology of Silica Fume Additives 

A.J. Allen (NIST) and R.A. Livingston (FHWA) 

X23A3 

Supplementary cementitious materials like silica fume. which are added to the cement 

mix and react with calcium ions in the pore solution. enhance the production of 

calcium-silicate-hydrate gel and modify the microstrncture in other ways. By combining 

ultra-srnall-angle x-ray scattering (USAXS) experiments on silica fume slurry 

suspensions with small-angle nentron scattering (SANS) experiments on hydrating 

cement systems, the effects on the microstructural development during cement hydration 

of adding silica fume have been studied. The USAXS n~easurements on the 

silica fume slnrries were perforrnetl using 10 keV x-rays and Ge(ll1) crystal optics. 

Each fume was slurried in a 4.0 water-to-solids (w/s) weight ratio suspension (fume 

volume fraction lo%), and sealed into a 1 mm-thick water-cell with x-ray compatible 

tape windows containing the fume. This concentration of fume gave acceptable 

(10-15%) x-ra,v pcnctration, and negligible m~~ltiple scattering. After background 

subtraction, nbsolnte calibration and tlesrnearing, the effective scattering-vector, h, 

range was 0.004 - 0.3 runpL. (Some SANS experiments were also carried ont to 

ext,entl the maximlnn 11 achieved.) The USA% h range was found snitahle for tleternlining 

the main part of the silica particle sizc tlistribution which showed very 

little variation arnong the hnnes. The Porotl scattering, which tlorninates the scnttering 

for h greater than 0.1 nmpl, yields sl~rface areas of around 14 x 10%~' 

for all of thc fnrne slurries. Since the 4.0 w/s ratio of each slurry implies a solitl 

silica vol~lrnc fract,ion of some lO%, the specific sl~rfitcc arcas of the solid flunes were 

tletlr~rctl to bc 60.000 nr2 kgp', an acccpt,ablt, V~LIIK~ for rrasorrahly well-tlispersctl silica 

fl~tncs. Using cr~tropy-rn~~ir~lirntioll 1n0thot1s to (leternline the volnnw-wrightctl 

particlc size tlistrihntion, the volnmc-wcightrcl mean particle tliarneters arc consistent 

lvith the expected characteristics of rc;tsonat)ly well-tlispersrtl fumes. antl the 

voll~n~e fractions are acceptaljly close to the nominal concentrations. Howrver. at h 

below 0.04 nmpi, differences in the USrZSS tlata are discernible among thr fnrnes. 

with an npturn in the scattering associatctl wit11 the Porotl scattering from coarse 

ft,atnrcs. The coarse featnrrs could cithrr bc atltlitional volnrnc fractions of intlepcutlcnt 

coarse particles. or. more likely. low-tlcr~sity agglorncratcs of thc particles 

already characterized in the sizc tlistrihutions. Such agglo~n~ratcs co~~ltl not be 

closc-packed, becanse. if this wcre so. strong interference effects ~vol~ltl appear in 

the VS-ASS data. TElI stntlics ant1 some preliminary laser scattering particle size 

analyses indicate that the silica finne particles floccnlate into large (several prntliarnetcr) 

loose assemblages. which. ncvertlleless, cannot casily bc broken 111) by 

sonic agitation. In tllc ovcrall study. a link was established bctween the existence 

of such coarse or agglomerated particles in the silica fi~rnes antl possible tleleterions 

rnicrostrl~ctl~ral evolution tluring cement hydration. The L*SASS stndies provided 

a11 111liclw access to the low h values reqnirctl for the salient agglomeration effects 

to be discerned in the fi~rnes. 

Exploring the Performance Limits of a Bonse-Hart Double-Crystal 

Ultra-Small-Angle X-Ray Scattering Camera 

A.J. Allen and G.G. Long (NIST) 

Experiments have been conducted to optimize and enhance the resolution. the 

signal-to-noise ratio, and the range, of a practical Bonse-Hart ultra small-angle 

x-ray scattering (USAXS) camera. By combining our existing USAXS monolith. 

the X23A3 monochromating optics. and a new monolith, specifically designed for 

the use of 100-mm-long crystals, it has been possible to increase the number of 

crystal reflections to 6 reflections before ancl 4 reflections after the sample. Each 

crystal has been surface-etched to eliminate Porotl small-angle scattering effects 

arising from strained regions near the crystal surfaces. The gap between the pair of 

Ge(ll1) crystals on each monolith has been reduced to minimize the through-pnt 

of parasitically-scattered x-rays. The beam-defining slits and ion charnher for the 

incident beam nornlalization have been placed before the n~or~ocl~ron~ating monolith. 

Thus a truly slitless antl windowless instrument geometry has been made 

possible through the monochromating monolith, the sample position, and the analyzing 

monolith. The critical air-path throng11 the instr~nnent has also been kept 

to a ~riinirrunn. Definition of thc bcarn position witahin the sample was determined 

11sir1g a magnifying x-ray vitlw camera antl a precision sanlple-stage ~not~ion. X 10 

tlccntle tlynarnic-range photocliotle x-ray detector was llsctl to measure the x-ray flnx 

transrnittetl throngh tllc instruruent as the analyzing nlonolith was rocked throl~gh 

ant1 then away fro111 the C:c(lll) Bragg angle. As in all ollr USAXS studies. the 

large tlynarnic range of the tletector enablrd an absolutc geornctric calibrat,ion of 

thc S:\SS intensity to br tnatle wit11 respect to the inritlrnt bcarn wit,llo~~t th? nrctl 

for a secontlary st:tntl;trtl. Use of the new USAXS configl~ration at an x-ray cnt~gy 

of 10 ke\' has resulted in ncar-theoretical h-' rocking-c~~rve tails down to intensities 

five decades below the rocking-curve peak. Brlow this intensity, some srnall-angle 

scattering is ol)scrvt~tl, bclicvcd to originate from tll~st particles in t,hc air. Eight 

tlecatles 11elow thc pcak intensity. the scattered intensity Ijccornes tlorninatctl ly the 

plrototliotlr dark-c~~rrent. \Vith a sarnplt. prcscnt, the nlinirn~~rn scat,tering-vrctor 

reached is close to t11e theoret,ical 0.00-1 nmpL for Ge(ll1) optics and 10-keV x- 

rws. and acceptable data statistics can be obtained in a scan taking Icss than 25 

rninutes. Fl~rther cxperiruents will extend thcsc er~l~ancernerlts to Si(ll1) optics, in 

order to take atlmntage of the high brilliar~ce ant1 srnall synchrotron opcning-angle 

of a third-generat ion source. 

Scattering Vector, h (nm-'1 

X23A3

tb 

F 

m 

I Morphology of Polyethylene/Carbon Black Composites * I X23A3 I 

G. Beaucage, S. Rane, D. W. Schaefer (U. Cinn.) K. Schwartz, M. Wartenberg 

(Raychem), G. G. Long, D. A. Fischer (NIST) and G. D. Wignall (ORNL) 

Carbon black is a common polymer additive that is used for purposes of reinforce- 

ment and for enhancing materials properties such as conductivity. This research 

pertains to a small-angle x-ray scattering (SAXS) study of a conductive grade of 

carbon black and carbon black/polymer composites. The SAXS from such materi- 

als displays a surface-fractal-like power-law decay over many decades of scattering 

vector, q. While SAXS by carbon blacks can be described in terms of surface-fractal 

models related to particles with fractally-rough surfaces, the existence of such self- 

similar surface roughness is not supported by electron microscopy data. It is instead 

proposed by the present investigators that the scattering represents a more compli- 

cated morphology including overlapping structural features and a power-law scaling 

of polydispersity. We have shown that power-law polydispersity in aggregate size 

can account for the observed scattering. Moreover, it has been possible to calculate 

a reasonable heterogeneity index for the aggregates using a power-law polydispersity 

model. The SAXS from carbon black in an amorphous polymer matrix was used 

to estimate the primary particle size and other nano-sized structural features of the 

carbon black, as well as to support a model based on changes in large-scale agglom- 

eration and on aggregate breakup at higher concentrations. When x-ray diffraction 

data were combined with the SAXS data, it was also possible to identify a scaling 

regime associated with graphitic layers in the primary particles. Differences in scat- 

tering between low and high concentrations of carbon black in polyethylene support 

a model based on large aggregate breakup and an associated linear agglomeration of 

aggregates in high concentration carbon black samples. The latter may be critical 

to understanding conductivity switching in these composites. 

Since one application of conductive carbon black composites with polyethylene is 

in circuit protection devices, where resistive heating leads to a reversible association 

of carbon black aggregates that controls switching between a conductive and a non- 

conductive state, these scattering results are very useful as an in situ tool to observe 

the morphological signature of this reversible structural change. 

* This work was supported, in part, by the Petroleum Research Fund of the American 

Chemical Society 

USAXS Determination of the Degree of Consolidation of Resin Par- 

ticles in UHMWPE Components 

A. Bellare and M. Spector (Harvard U.) 

X23A3 

Consolidation of ultra-high-molecular-weight polyethylene (UHMWPE) resin 

powder particles during processing of UHMWPE components has been a concern 

in the manufacture of total-joint-replacement prostheses. While UHMWPE resin is 

beneficial for wear performance in total-joint-replacement prostheses, processing of 

the resin is difficult since resin particles do not flow, even at temperatures above 

the melting point of polyethylene crystallites. High pressures and elevated temperatures 

are required during ram extrusion and compression molding processes to 

consolidate UHMWPE resin particles. Recently, it has been shown that wear debris 

retrieved from tissues in cases of failed total hip arthroplasty resemble the size 

and shape of original resin particles, suggesting that poor consolidation of resin can 

contribute to wear. It is therefore essential to optimize processing parameters for 

each type of UHMWPE resin to obtain a high level of consolidation. 

In this study, ultra-small-angle x-ray scattering (USAXS) at X23A3 has been used 

to compare the degree of consolidation of UHMWPE components of various resins. 

We hypothesize that a lower degree of consolidation leads to a larger number of 

voids in components. Since voids are usually larger than crystallites of UHMWPE, 

their presence would lead to scattering at smaller angles. (The only exception is 

Hylamer in which there are crystallites of sizes comparable to those of voids.) 

Fig. 1 shows USAXS data from components that were molded for 5, 10 and 

15 minutes. The decrease in scattering with increase in molding times is a direct 

consequence of lower number of voids and a greater degree of consolidation. 

Visual inspection revealed the presence of voids in the 5 and 10 minute molded 

samples, but no significant voids in the 15 minute molded sample. These results 

show a correlation between USAXS intensity and the number of voids associated 

with concolidation. In another part of this study, USAXS results from different 

resins were compared, and a wide variation in the amount of void scattering was 

observed. For example, it was learned that the 2-million-molecular-weight resins 

have a lower number of voids. indicatina - a higher - degree - of consolidation, compared 

to the 5-million-molecular-weight resins. 

Figure 1. USAXS intensity versus scattering vector for three molding times.

tj 

t3 

a Accelerated Aging of Gamma-Radiation-Sterilized Hylamer Ac- 

I Grazin~-Incidence X-ray-Diffraction Topography I X23A3 I 

0 X23A3 

etabular Components D. R. Black (NIST) 

A. Bellare and D.C. Sun (Harvard U.) 

Post gamma sterilization aging of UHhIWPE components of total joint replacement 

prostheses has received considerable attention in recent years due to evidence 

of embrittlement with age. Several accelerated aging protocols have been developed 

and compared to real time shelf-life aging of UHhIWPE. These protocols 

are useful in the development of new methods of sterilization that aim to prevent 

embrittlement of UHLIWPE with in-vivo age. In this study, we have utilized a 

previously-developed accelerated-aging protocol to investigate post gamma sterilization 

(in air) aging of a Hylamer acetabular component. Ultra-small-angle x-ray 

scattering (USAXS) at X23A3. FTIR, antl DSC were used to characterize the degree 

of oxidation antl the accompanying changes in microstructure. 

USAXS measurements were performed on the X23A3 beamline at the National 

Synchrotron Light source. Sampling volumes were 1 mm by 3 mm by 1 mm. Scattering 

from voids was eliminated by subtracting the scattering curves obtained 

from melted samples (T = 190°C). The USAXS data measured from as-received 

antl from agetl Hylamer revealed the presence of two peaks, one at ultra-low angles 

(attributed to the presence of large crystallites formed at high pressure) and 

a broad peak (attributed to crystallites that are similar in size to coriventional 

UHLI\.\TPE crystallites. The existence of a bimodal distribution of crystallites is 

snpportetl by previous DSC observations. The spacing between high-pressure crystallites 

(approximately 250 nnl) did not change with accelerated aging. I-Iowevcr, 

there was a discernable rhange in the spacing between the crystallites of smaller 

tliniensions. The inter-crystallite spacing changed from 34.5 nrn down to 21 nm 

(d11.5 nm). These results, together with previot~sly-observet1 changes in intercrystallite 

spacing in convcntionsl UHhIiVPE, indicates that recrystallization ind~~cetl 

1?\. gamrtla-sterilization (in air) aging occurs by the same rr~cct~ar~isrn in both types 

of rrricrostructl~res. However, clue to a much higher degree of crystallinity in agetl 

Hylarner, compared to aged cor~ventional UHhIIVPE, oxidative aging could be of 

greater concern in Hylamer from the staritipoint of cmhrittlement antl wear. 

Figure 1. US-AXS intensity versus scattering vector for as-received Hylamer. aged 

Hylamer. and conventional UHlII\-PE. 

The basic principle of x-ray diffraction topography involves two-dimensional 

imaging of the x-ray diffracted intensity from a selected set of crystal planes in 

the sample. The sample diffracts the x-rays in either the reflection geometry to 

emphasize information on the microstructure near the surface, or in the transmission 

geometry to emphasize the microstructure of the bulk. \Jery small variations 

in the crystalline lattice spacing, Ad, or very small changes in the local crystallographic 

orientation. AO, change the diffraction condition and thus the diffracted 

intensity. Changes in local orientation and the local lattice spacing are the result of 

crystallographic defects such as dislocations, stacking faults, inclusions, voids. and 

inhomogeneous strain. Although the best spatial resolution available with x-ray 

topography is just under a prn, much smaller defects can be detected if there is a 

strain field around the defect. 

As an example. x-ray topographs from single-crystal sapphire typically show longrange 

inhomogeneous strains or lattice curvature. subgrains, antl residual polishing 

damage. Although sxh scratches may not be visible optically, they are often visible 

in the x-ray iniagc if, even after the scratch itself was removed, thr lattice below the 

scratch was disturbed and that damage remains. To further improve the ser~sitivitv 

to surface microstructures. grazing-incidence topography has been used on X23A3. 

In this mode, a sct of diffracting planes, not parallel to the surface, are chosen 

to diffract. By ac!justing the energy of the incitlent x-ray beam, one can choose 

a diffraction angle near the angle for total external reflection of the x-rays. IVhen 

this occurs, there arc no beams entering the sample, only a11 exponentially-clecaying 

evanescent wave. This condition changrs the surface sensitivity of x-ray imaging 

from tens of pm to tens of nm. In Fig. I, when the incitlent rncrgy of the x-ray 

beam was chaugetl by 100 eV, the incident angle changed by 0.25", antl a riluch 

greater sensitivity to surface microstruct~~re of this sapphire crystal was achieved. 

This microstructnre is directly attributable to the fabrication nlethotls. 

Figure 1. Depth-sensitive observation of the microstructure of single-crystal sap 

phire. The image on the left was taken using an incident x-ray beam enerp 100 

e\- lower than that in the image on the right.

Small-angle X-ray Scattering Study of the Formation of Colloidal / X23A3 / 

Silica Particles From Alkoxides: Primary Particles or Not? 

H. Boukari (U. Maryland & NIST), M. T. Harris (U. Maryland) & J. S. Lin (ORNL) 

The formation of colloidal silica particles from tetraethyl-orthosilicate (TEOS) in 

several alcoholic solvents under base-catalyzed conditions was investigated by means 

of X-ray scattering, SAXS ['I and USAXS. For low concentrations of water, one can 

follow the dynamics of formation and growth by measuring the scattered intensity 

profiles at various times following the initiation of hydrolysis and condensation 

process. The high-q data are analyzed within the concept of fractal geometry and 

the time-dependent fractal dimension is determined from the power-law region. 

Furthermore, changes in the radius of gyration are determined from the Guinier 

low-q regime. Remarkably, we find that, after an induction period, the first particles 

to appear in the solution are mass-fractals characterized by their polymeric, low- 

density structure. This stage is followed by an intra-particle densification process 

and smoothing of the interface leading to the usual compact non-fractal, stable 

structures. Interestingly, under the same conditions, the initial particles are sizable 

(radius of gyration is greater than 5 nm) and the initial size depends strongly on 

the solvent. We are studying these results in light of results predicted by current 

growth models that have been proposed. 

H. Boukari, J. S. Lin, M. T. Harris, J. Colloid. and Int. Sci., (1997) in press. 

The Effects of Hydrogen Peroxide and Sterilization on the Structure 1 X23A3 1 

of Ultra-Hiah-Molecular-Weinht Polvethvlene * 

M. Goldman, R. Gronsky, L. Pruitt (U. of C., Berkeley) and G. G. Long (NIST) 

Ultra-high-molecular-weight polyethylene (UHMWPE) is an important material 

for total joint replacement surgeries, and, as such, must be sterilized before placement 

into the body. It must also perform well as a function of time, or else revision 

surgeries will be needed. In this research, the effects of hydrogen-peroxide aging 

and gamma-irradiation sterilization on the structure and morphology of medicalgrade 

UHMWPE were studied. The microstructural changes that were induced 

via sterilization and accelerated by aging were observed by means of small-angle 

x-ray scattering (SAXS) measurements on X23A3. Differential-scanning calorimetry, 

density gradient column measurements, and transmission electron microscopy 

were also used to characterize the structure. Based on the results, a mechanism for 

the oxidation of UHMWPE was proposed in which oxygen is incorporated into the 

amorphous phase of the polymer, leading to strains and breaking of tie molecules, 

which in turn leads to embrittlement and microcracking within the microstructure. 

The SAXS data for four samples aged 11 months are shown in Fig. 1. An interference 

peak near scattering vector h = 0.0125 k1 can be seen. This interference 

peak is associated with the long period in the UHMWPE structure, which is of the 

order of 515 A. The sandwich size is the smallest in the untreated sample (n-air) 

and greatest in the hydrogen-peroxide-aged and gamma-irradiated sample (g-hp). 

Enhanced scattering at low-h, which is seen in the scattering from some of the 

samples, is interpreted as Porod scattering from microcracks. Taken together, the 

lamellar microstructure is best-defined (least tortuous) in the unsterilized sample 

aged in air (n-air), and this sample shows no evidence of microcracking. The lamellar 

microstructure is the least well-defined (most tortuous) in the gamma-irradiated 

sample aged in hydrogen peroxide (g-hp), and this sample shows the most microcracking. 

This is the first time that microcracking has been observed directly in these 

samples, and the results are consistent with mechanical properties measurements. 

Figure 1. SAXS cross section as a function of scattering vector h for four samples 

of UHMWPE. n-air = not irradiated and aged in air, g-air = gamma irradiated and 

aged in air, n-hp = not irradiated and aged in hydrogen peroxide, g-hp = gamma 

irradiated and aged in hydrogen peroxide. 

* This work is supported, in part, by the NSF under Contract No. 44244422178.

- 

I Ultra-Small Angle X-Ray Scattering by Single-Crystal Aluminum 

E3 -. - - -. 1 

[ Ueformed In Situ - 

L. E. Levine, G. G. Long and R. Thomson (NIST) 

X23A3 1 

Ultra-small-angle x-ray scattering measurements on single crystal 41, deformed 

in situ, were carried out. Stress-strain data mere accumulated simultaneously with 

the x-ray scattering data to follow the evolution of dislocation structures from 0% 

strain to 18% strain. Using long-wavelength x-rays, it was possible to follow the clevelopment 

of dislocation structures while avoiding accidental Bragg diffraction. The 

USAXS results can be understood in terms of scattering by the edge components 

of the tlislocations antl of scattering by the clislocatio~l walls in "carpet structures." 

The scattered intensity is a strong function of the orientation of the scattering vector 

relative to the configuration of the tlislocations. At low strai~ls, it was fo~md 

that the amount of scattering from the dislocation structures was roughly constarrt. 

At higher strains. the scattered intensity irlcreased tlramatically. Interestingly, this 

apparent change in the tlislocation configuration does not corrcsporltl to any feature 

in the measured stress-strain curve. Those results are currently being interpreted 

usi~lg a newly-developed theory of small-angle scattering by tlislocatiorl structures. 

111 a companion x-ray topography experiment, also carried OII~ on X23A3, the 

carpet str~~ctures were imaged, and srrlall rotations across dislocation walls were 

ohscrvctl and mcasurrd. Surprisingly, the grown-in tlislocations and the carpet tlislocations 

wrrc sometimes observed to have no measl~rablc infl~~cnce on one another. 

The mobilc tlislocations on the primary slip plarres simply cut through the existirig 

irnrnobilc dislocations. 

Use of Ultra-Small-Angle X-Ray Scattering to Measure Grain Size 

of Styrene-Butadiene Block Copolymers 

R. T. Myers. R. E. Cohen (LIIT) and A. Bellare (Harvard U.) 

X23A3 

It is well-known that appropriate processing techniques can produce essentially 

perfectly ordered block coploymer morphologies with a single texture extending 

throughout the macroscopic dimensions of a specimen. The characteristic rcpeating 

length scale? d. of these morphologies is dictated by the molecular weights of 

the constituent block sequences and is on the order of 100 A. In the absence of 

extraordinary processing procedures, a second important length scale appears in 

the block copolymer. The perfection of the morphology is broken up into grains, 

each of which contains the ordered morphology of length scale tl but with essentially 

rar~tlom orientation relative to the specimen boundaries. These large grains 

typically exhibit a characteristic size. D, which is one or more orders of rnagriitutle 

larger thau the morphological length scale, tl. It has been shown that the grainy 

structure cau influeuce important physical properti~s of this material such as gas 

transport. 

Conventional small-anglc x-ray scattering (SAXS) techniques have been used 

for tlecatles to cliaractcrizc block copoly~ncrs at the morphological lerlgth scale tl. 

Recently. ultra-SAXS (USAXS) me;wurcments at X23A.3 have been able to probe 

sigr~ificantly larger morphological fcaturrs, previously observable only through the 

use of various microscope tcchniqucs. The spacing, d. was revealed directly by the 

data. Althougl~ no resolvable pcaks apprarctl as n rrsdt of scattering by the grains, 

MI ar~alysis of the Porotl tail of the grain scattering. antl the use of the scattering 

invarierit, cr~ahletl a reliable cstimntc of the grain sizr, D. Intlrprntlrnt observation 

of the grains in the bulk spccimcn by Inrnrls of trnrlsmissiori electron microscopy 

corrohoratetl tlle USASS analysis. Thus. USASS cm be usctl t,o prot+tle a relialjlr 

and statistically-sigr~ific;~r~t c1lnr;~ctcriz;~tiorl of bulk sprcimens of block copolymers 

sirnultar~eously at hot11 of tht ;thovc-r~~c~ltioncct lrngth srales. 

Figure 1. Smeared intensities as a function of scattering vector q for KRO-3 resin 

diluted with various amounts of cumene. The uppermost plot is at the proper 

position on the \-ertical axis. The other curves were shifted successively clonnrvard 

for clarity of presentation. The downxvarcl shifts are: 1.0 decade. 1..5 decade and 2.0 

tlecatles respectively.

X-ray Topography of Superalloy Single-Crystal Castings X23A3 1 - 

R. Napolitano, R. Schaefer and D. R. Black (NIST) 

The demand for larger and more complex superalloy single-crystal components in 

both aerospace and in land-based gas turbines has increased dramatically the degree 

of process control required for the reliable production of defect-free blades and vanes. 

The mechanisms responsible for the formation of low-angle grain boundaries is not 

well understood, and these defects have not been well-characterized in production 

castings. The objective of this work is to characterize the misorientation in several 

castings such that the conditions leading to the development of low-angle grain 

boundaries may be identified, better understood, and ultimately eliminated. 

Grain defects are most often observed near mold corners or in other areas of 

non-uniform cross section. For this reason, several test castings were produced with 

varying geometries. The castings were made with high-temperature alloy Rene N5. 

Each casting had one or two regions of non-uniform cross section, which were sec- 

tioned and examined by means of monochromatic x-ray topography at X23A3. In 

some areas, a series of parallel sections were imaged over a large angular range 

to provide three-dimentional information concerning the crystallographic orienta- 

tion. With this technique, continuous and discontinuous misorientations can be 

distinguished and traced through the casting, yielding a qualitative and a semi- 

quantitative understanding of how they are related to the mold geometry. This is 

vital information because it can be coupled with thermal analysis of the casting 

process to provide a complete picture of defect formation at any specific location 

within the component. In this way, the underlying mechanisms for defect formation 

may be revealed. 

Particle Sizes and Size Distributions in Additives to Polymeric Sys- 

1 tems 

K. C. Sheth and Y. Gao (GE R&D) 

X23A3 

- 

The goal of these experiments is to develop techniques to determine average 

particle sizes and size distributions of additives (such as impact modifiers and flame 

retardants) in polymeric systems. The USAXS facility at X23A3 has been used to 

probe particle sizes up to approximately one micrometer in size. Hence this facility 

fills the gap between conventional SAXS (for the smallest sizes) and light scattering 

(for the largest sizes). 

The conventional approach to particle size analysis is transmission electron mi- 

croscopy (TEM), but TEM samples only a limited area and it is difficult to obtain 

a statistically-significant sampling. USAXS, on the other hand, provides a rapid, 

non-destructive, robust technique for obtaining the required information. We have 

been studying a variety of polymeric systems, containing a variety of additives. 

In particular, we have examined isotropic, spherical additives (rubber additives as 

impact modifiers) and anisotropic additives (such as globular or fibrilar particles). 

TEM data is available on these systems. The results from the analysis of the US- 

AXS data for spherical particles are in excellent agreement with the TEM data. 

For example, for a rubber particle dispersion in acrylonitrile-butadiene-styrene, the 

average particle size is 848 nm, which is in good agreement with the corresponding 

TEM result of about 800 nm. (TEM is expected to yield smaller numbers than the 

actual size because there is two-dimensional averaging resulting from the slicing of 

spheres.) The particle size distribution derived from the USAXS data also corre- 

lates well with the TEM results. An analysis of the USAXS from the anisotropic 

particles is currently in progress.

Characterization of an Er LIII Bragg Polarizer Grown by Molecular 

Sample-angle Feedback For Improved Reproducibility in Diffraction 

I X23B 1 Beam Epitaxy Anomalous Fine-structure (DAFS) Spectra 

I X23B I 

J. 0. Cross, B. R. Bennett, RI. I. Bell (NRL) and K. J. Kuhn (Intel Corp.) 

A wide band linear Bragg polarizer for photon energies around the Lrrr absorp 

tion edge of erbium was grown from a ternary semiconductor alloy using molecular 

beam epitaxy.[l] The active optical element is an 8 micron single crystal film of 

In.j~Ga.*gSb grown on an oriented GaAs (001) substrate. The composition of the 

alloy mas calculated using Vegard's rule, assuming total relaxation of the epitaxial 

layer. to give maximum linear polarization for the target energy of 8358 eV using 

the (006) Bragg reflection. The full-width at half-maximum of the energy acceptance 

was measured to be 27 eV, centered at 8359 eV, by scanning the incident 

energy with the polarizer and detector held fixed at 0 = 45 cletrees and 20 = 90 

cleurees, respectively. 

711 J. 0. Cross, et al.. Appl. Phys. Lett. 70 (1997) 2224. 

J. 0. Cross, W. T. Elam, V. G. Harris (NRL), J. P. Kirklans (SFA), C. E. Bouldin 

(NIST) and L. B. Sorensen (U.W.) 

Diffraction anomalous fine-structure (DAFS) experiments measure integrated 

Bragg peak intensities as continuous functions of energy in the vicinity of absorp 

tion edges.[l] Often, the peak intensity of the 0 rocking-curve is proportional to 

the integrated intensity over the energy range of the fine-structure (typically 1000 

eV), and it is sufficient to track the Bragg peak as the incident energy is scanned. 

This "peak-tracking" mode of collecting DAFS data significantly reduces the time 

required for a complete spectrum, however, while the Bragg angle as a function 

of energy can be calcl~lated easily and given as a command to the diffractometer 

controller, any systematic error in addressing the goniometer or monochromator 

motors will result in distorted spectra. One way to insure accurate tracking of the 

peak is by introducing a small rcfcrcnce oscillation on the sample angle. protli~cing a 

corresponding fluctuation in intensity at the detector that can be fed to the input of 

a lock-in amplifier. A piczoclcctric actuator-driven sample stage has been designed 

anti tcstecl as part of a sample-angle feedback circuit for locking on to the maximum 

of thc rocking curve as the incitlcnt photon energy is scanned tli~ring DAFS 

cxpcrirncnts. Dran~atic improvcmcnts in reproducibility wpre observed, as well as a 

decrease in systematic glitches caused by roundoff errors in the motor arldrrssing. 

[I] H. -7. Stragicr, ct al., Phvs. Rev. Lett. 69, 3064 (1992). 

8150 8400 10 8000 8100 R200 8700 RJOO 8500 

Energy (eV) 

Enersy (eV) 711511 7lfXl 7150 -21Yl 7150 77110 77511 

Enerp (eV) 

Figure 2. Fe K-shell DXFS. Software 

Figure 1. Diagram of the sample stage peak tracking with and without atldi- 

Figure 1. Response of the polarizer as 

a function of energy in the vicinity of 

the Er L~rr absorption edge. The inset 

Figure 2. Reflectivity vs. Energy around 

the (006) Bragg peak. The substrate 

sho~t-ing the piezoelectric actuator (a) 

loading spring (s) to provide the restoring 

force. and goniometer head mounting 

tional hardware feedback locking. The 

inset shows the reflectivity around the 

(Fe 40A4/Si 14.1\) x 2.3 (001) multilayer 

shows the experimental arrange~nent. peak is reduced by the overlayer. post (P). peak.

U1 

EXAFS Study of the Local Structure Around Mn in Annealed 1 X23B 1 

ZnS:Mn Nanocrystals 

J. 0. Cross, W. T. Elam, D. Hsu, H. F. Gray, J. Yang, M. Smith and B. R. Ratna 

(NRL) 

The quantum yield of Mn-doped ZnS nanocrystals grown in the bicontinuous 

cubic phase (BCP) of a surfactant and water system [I] has been shown to depend 

on Mn concentration. These crystallites are highly monodisperse, and in the 35A 

diameter nanocrystals, a peak in the quantum yield occurs at 0.7 mole percent, or 

approximately one Mn atoms per particle. Recently, an additional increase in the 

quantum yield has been shown to follow a structural change induced by annealing 

the nanocrystals. We have used extended x-ray absorption fine tructure (EXAFS) 

to study changes in the local environment of the Mn luminescent centers caused by 

annealing. 

The R-space transforms of background subtracted fluorescence EXAFS data from 

three ZnS:Mn phosphor powders are shown in Figure 1. Background subtraction 

and R-space fits were performed using AUTOBK and FEFFIT 121, with theoretical 

x calculated by FEFF7.131 The Mn-S distance of 2.409(7)A determined for the 

as-grown nanocrystals is approximately 0.03A shorter than the Mn-S distance of 

2.443(6)A determined for the bulk standard, consistent with a previous EXAFS 

study of 30-35A ZnS:Mn grown by precipitation 141. In the BCP grown samples, 

however, the amplitude of the Mn-S nearest neighbor shell of the nanocrystals, 

relative to that of the bulk, is lower than that reported in 141, and the second peak 

due to the Zn and S next neighbors is absent in the as-grown nanocrystals. The 

absence of the second peak could be due to disorder in the next neighbor shells, 

or to the Mn impurities migrating to the surface of the crystallites during growth. 

X-ray diffraction measurements of BCP grown samples prior to annealing suggest 

that for particles of ca. 30A and smaller, the cubic (zinc-blende) lattice distorts 

tegragonally 151, consistent with disorder in the Zn and S next neighbor distances. 

After annealing, the EXAFS first shell amplitude remains nearly unchanged and 

the second peak re-appears. In addition, annealing causes an increase in the first 

neighbor Mn-S distance to 2.436(8)A, close to that of the bulk. 

[I] J. P. Yang, et al., J. Phys. Chem. 100 17255 (1996). [2] M. Newville, et al., 

Phys. Rev. B 47 14126 (1993) [3] S. I. Zabinsky, et al., Phys. Rev. B 52 2995 

(1995). [4] Y. L. Soo, et al., Phys. Rev. B 50 7602 (1994). [5] S. B. Qadri,et al., 

Appl. Phys. Lett. 70 1020 (1997). 

Figure 1. R-space Fourier transform of EXAFS data from bulk standard (heavy 

solid line) and ZnS:Mn nanocrystals before (dashed line) and after (thin solid line) 

annealing. 

DAFS Study of the Interfaces of an Fe/Si Multilayer 

J.O. Cross, V.G. Harris, W.T.Elam (NRL) and M. Newville (U. Chicago) 

Fe/Si multilayers are interesting for their magnetic properties, saturation mag- 

netism (M) and anistropy field (Hk), and as x-ray optical components for magnetic 

circular dichroism. The boundary between the Fe and Si layers has an intermixing 

region which which can be disordered, or form an iron silicide. The presence of the 

crystalline silicide affects the magnetic properties of the multilayers and is therefore 

of technological interest, however, determining the thickness and structure of the 

crystalline spacer has so far been unanswerable using diffraction or XAFS. [l] 

While XAFS can, in principle, be used to determine the number and distances of 

Si near neighbors, as well as the presence of order in the Fe and Si next neighbors 

around the Fe centers, the thickness of the silicide layers are on the order of 10% of 

the Fe layers, so that XAFS from the interface is lost in the signal from the rest of the 

film. DAFS gives the same kind of local structural information as XAFS, but also 

uses the long-range order of the material to select the fine-structure from a subset of 

the resonant atoms.[2] Since the intensities of the multilayer peaks are proportional 

to the Fourier components of the electron density normal to the interfaces, the 

DAFS on each peak samples a different subset of the Fe atoms. Figure 1 shows the 

reflectivity of (Fe 40A/~i 14A)x25 multilayer and Figure 2 shows the Fe K-shell 

DAFS measured on the (OOl), (002) and (003) multilayer Bragg peaks of the same 

sample. Small difference observed in the extended DAFS confirm the presence of 

at least two different local environments for the resonant Fe atoms. Since the x-ray 

polarization is confined to x-y plane in these reflectivity measurements, the DAFS 

is sensitive to the in-plane bond lengths around the Fe sites. The DAFS will be 

analyzed by solving for the anomalous scattering amplitudes f' and f" and then 

combining the X" fine-structure from these three reflections and the XAFS subject 

to a model that is consistent with the reflectivity to isolate the signal from Fe sites 

at different positions in the bilayer.[3] 

[I] J. A. Carlisle, et al., Phys. Rev. B 53, R8824 (1996). [2] H. J. Stragier, et 

al., Phys. Rev. Lett. 69, 3064 (1992). [3] J. 0. Cross, et al., J. Phys. IV France 7 

(Colloque), C2-745 (1997). 

Figure 1. Reflectivity from a (Fe 40A/si 

14A)x25 multilayer at 7412 eV. The 

DAFS measurements were made at the 

maxima of the (OOl), (002) and (003) 

peaks. 

X23B 

Figure 2. Fe K-Shell DAFS from the 

(OOl), (002) and (003) multilayer peaks. 

Differences between the fine-structure 

features are visible in the intensity data.

Quantitative Speciation of Cr at ppm Concentrations Using Chemo- I X23B ( 

metric Modeling of XANES Spectra 

J. 0. Cross. R. E. Shaffer, TY. T. Elam, S. L. Rose-Pehrsson (NRL) and J. P. 

Kirkland (SFA, Inc.) 

The ability to differentiate chemical species using x-ray absorption near-edge 

spectroscopy (XANES) has been clemonstratecl previously.[l] however, most existing 

methods reqnire separate measurements of the spectra from model compounds to 

identify a signature for each species. More recently. soft chemical analysis ~ncthocls. 

such as principal components analysis (PCA) antl chernornetric modeling or partial 

least- squares regression (PLS). have been applied to determine the number of 

unknown species present in environmental sarnples for which laboratory standards 

may not be available.[2] Based on these ideas. we have set out to determine a lower 

limit on the quantitative differentiation of Cr species using PCA and chemometric 

rnotleling of XXNES spectra. In previous stutlies,[l] the pre-edge featnre Figure 

1(a) observed in componntls with the Cr(V1) valence has been used to tlcter~nine 

t,he ratio of Cr(V1) to Cr(Il1) by comparing t,lw integrated peak intensity to the 

absorption step height. Tl~ere is an intlerent limit to the qnnntitativc accuracy of 

t,his method sincc thr pcak:step ratio is not the same for all Cr(V1) compo~l~~tls, e.g.. 

IXa2CrO.l and K2Cr207 in Figure l(inset). Soft modeling mcthotls make use of the 

entire XANES spectr~nn, wit11 the strongest weight given to regions s~~ch as Fignrc 

l(a). (b) ant1 (c). that cl~ange most between samples. The goals of this expcrirnerlt 

were 1) to tlcternlinc the rnunber of species present in a group of sarnples using 

PCA ant1 2) to set n bound on the quantit,ativc accuracy of PLS for tlcterrninirig 

the amo~mt of known species. i.e.. laboratory stantlartls, present in the sarr~ple at 

low total Ck c~~~cci~tration. For this initial study. XANES data WC~C co11~ct~1t1 from 

dry ~nistl~res of Cr(Lr1) 2nd Cr(II1) in sarltl at conrcnt,rat,ions from 1000 ppru tlown 

to 7 pprn by weight. F'ignre 2 sl~ows the results of speciat,ion by PLS ou n~ixtures 

with tliffercnt ratios of Cr(1II) to Cr(\-I) and for se\wal total Cr cor~ccntrations. 

PC11 tlctcrn~inetl the presence of two conlponent,s antl speciation using PLS gave a 

mean rrror of 3.62% in the Cr(\'I) to C:r(III) ratio for total Cr 1)ctween 300 and 

1000 ppm, autl 6.59% for 100 pprn and lower. 

51. L. Peterson, ct al.. ,T. Phys. IY France 7 (Colloque C2. 1997) C2-781. 

S.R. \\'asscrrnan. .J.Pliys. I\- France 7 (Colloqne C'2. 1997) C2-203. 

Fignre 1. PC:\ determines the nnrnher 

of species and soft modeling nlakcs use 

of the entire X--\XES spectrum. weighted Fignre 2. Results of chemometric moclelin 

regions such as (a). (b) and (c) that ing for mixtures of Cr(\*I) and Cr(I1I) at 

change most between sanlples. The ratio concentrations from 1000 pprn to 7 ppm 

of pre-edge peak to step height is not the (a) preclictccl ratio vs. actual antl (b) ersame 

for all hexavalent Cr cornpo~~~lcls. ror In percent Cr(T.1) vs. concentration. 

Processing of Pure-Phase MnZn-Ferrite Using High-Energy Ball 

Milling: An X-Ray Absorption Fine Structure Study 

D.J. Fatemi. V.G. Harris(NRL), and J.P. Kirkland(SFA) 

X23B: 

X23A2 

31n.sZn.;FeaOa~ ferrites were processed by mechanical alloying a mixture of the 

elemental oxides hInO. ZnO. and Fez03 in a high-energy shaker mill. The structure 

of the milled mixtures was studied via X-ray diffraction (XRD) antl extended 

X-ray absorption fine structure (EXAFS) measurements. Broad diffraction peaks. 

corresponcling with those of the spinel ferrite phase. were detected via XRD after 

180 min. of nlilling (the sample of shortest milling duration). whereupon a pure 

phase spinel ferrite (as judged by XRD) was measured in the 1260 min. milled 

sample. The atornic fraction of metal ions existing in the ABaO.1-type structure, 

where A and B refer to tetrahedral and octahedral coordinated cations. was measured 

as a fimction of nlilling tluratio11 by EXAFS. This analysis reveals that the 

con\rersion of ~netal ions from their elemental oxide strnctures to the spinel phase 

occurs near-linear with milling time witti 50% of the oxides converted after approximately 

500 minutes. AIultiple-scattering EXAFS motleling was applied to rncasllre 

the site distribution of the variol~s cations as a function of milling time. Compared 

with an eqnilibriurn 51n.r,Zn.~Fe~061 powder sarriple. which was prepared by tratlitional 

fire and grinding techniques, thr ~r~cctiar~ically alloyed ferrit,e sarnples rx11il)it 

a higher fraction of Fc antl A111 cations on the A-sublattice. while an unl~sl~ally high 

population of Zn cations rcsitles or1 the B-sublattice. The site distrilx~tion cm he 

inferred q~~alit,atively from Fig. 1. in wl~icli peaks labeled A and B arisc Iargcly 

from occupation of the absorbing atom on :\-sites and B-sites, rcspcctivcly. 

Radial Coordinate (.A) 

Figure 1. Fourier transformed (a)Fe. (b)lIn. antl (c)Zn EX-IFS data from IInZn- 

ferrite formed after 10 hrs of milling and from the standard.

-3 

Magnet to Volume Effects in R2Fe17-,Al,N, (R=Er,Pr) Com- 

1 X23B I idence against Ba Site Pr Substitution I X23B 1 

EXAFS Measurements of Non-Superconducting PrBa2Cu3O6.~: Ev- 

V. G. Harris, D.J. Fatemi, V. M. Browning, M. S. Osofsky, (Naval Research Lab- 

oratory), and T. A. Vanderah (National Institute of Standards and Technology) 

Extended X-ray absorption fine structure (EXAFS) measurements on non- 

superconducting PrBaaCu3Os.s are reported. The EXAFS analysis reported here 

involves the least-squares fitting of the phase and amplitude of experimental k-space 

data using a linear combination of simulated Pr(Y)-site and Pr(Ba)-site LII EXAFS 

data. The simulated Y- and Ba-site Pr LII EXAFS data were generated using the 

multiple-scattering ab initio FEFF 6 codes of Rehr et al., where the FEFF input 

files were generated using ATOM 4.2 codes of Ravel. The calculated best fit data 

contains 0% Pr on the Ba-site. Because the Pr(Ba)-site LII FEFF is nearlyn/2 out 

of phase over a wide range of low-k values with respect to the Pr(Y)-site LII FEFF 

the results of the fitting analysis are unambiguous, with the results establishing that 

only dilute (i.e.< 1%) amounts of Pr can occupy the Ba sites in this compound. It 

is noteworthy that the substitution of even dilute amounts of Pr on the Ba-site lead 

to a significant deterioration of the goodness of fit, as judged numerically by the 

X2-fitting parameter and by visual inspection. This is illustrated in Fig. 1 where 

one sees the appearance of new fine structure peaks at k= 5.15k1 and 8.05k1 

that do not correspond with the experimental data. This occurs when just 1% of 

Pr is allowed to occupy Ba sites. A second approach to the fitting analysis involved 

relaxing the phase constraint. This allows an additional degree of freedom to the 

fit and would presumably allow a larger fraction of Pr to reside on the Ba-site. In 

physical terms this is analogous to allowing local dilation or contraction of the local 

environment by the substitution of the Pr ion on the Ba-site, as might be expected 

based on the mismatch in atomic radii between Ba and Pr. The best fit obtained in 

this fitting approach also had 0% Pr on the Ba-site. These results present a serious 

challenge to models which rely on Ba-site Pr substitution as an explanation for the 

lack of superconductivity in PrBazCu307-6 

0.4- 

0.2- 

2 O! 

-0.2- 

. . 

-experimental 

st Fit (calc.); 0% Pr on Ba-sitest 

Fit (calc.); 1% Pr an Ba-site- 

-0.4~""""'""'""'""'"""""""'~ 

2 3 4 5 6 7 8 9 1 0 

Photoelectron Wave Vector (k') 

Figure 1. Experimental Pr LII EXAFS and the best fit data for the cases when 0% 

and 1% Pr ions occupy the Ba-sites. The arrows indicate gross deviations from the 

experimental data introduced by the inclusion of 1% Pr on the Ba-sites. 

pounds Studied via EXAFS 

V.G. Harris, D.J. Fatemi, (Naval Research Laboratory), K.G. Suresh, and K.V.S. 

Rama Rao, (India Institute of Technology) 

Extended x-ray absorption fine structure measurements of the Fe K, and Pr and 

Er LIII absorption edges, were carried out to elucidate the relationship between 

the local structure and magnetism in A1 substituted, nitrogenated (Er0.5Pr0.5)2Fe17 

permanent magnets. Figure 1 is a plot of the FT Fe EXAFS collected from the Alsubstituted 

and nitrided samples, together with data from the parent compound. 

The inset panel depicts a plot of the average Fe-Fe/Al bond distance ( Fe-FelAl) 

and the average Fe-Fe/~l Debye Waller Coefficient ( Fe-FelAl) calculated 

for the atoms contributing to the NN peak as a function of x. Because the NN 

peak of Fe is dominated by other Fe and A1 atoms that are distributed on 4 inequivalent 

sites (i.e. 6c, 9d, 18f, 18h) the environment is described as an average 

Fe-Fe/Al bond. This simplification reduces the number of adjustable parameters in 

our fitting analysis from as many as 12 to no more than 3. Upon nitrogenation the 

F~-F~/A~ increases 0.86% from that of the parent compound. This result is a 

direct measurement of the dilation of the Fe coordination sphere and reflects a positive 

magnetovolume response of the Fe sublattice due to nitrogenation. With the 

substitution of A1 we observe that F~-F~/A~ decreases abruptly (rel. -0.6%), 

plateaus, and then continues its decrease. Although, others have reported a positive 

magnetovolume response to the substitution of A1 (x

td 

to 

3 

XAS Studies of Preferential Site Distribution of Ta and Pt in CoCr- 

Based Films* 

K. M. Kemner (ANL), V. G. Harris. SV. T. Elam (NRL), Y. C. Feng, D. E. Laughlin 

(ChIU), J. C. VToicik (NIST). and J. C. Lodder (hIesa Research Institute) 

CoCr-based alloy films are presently the mainstay mangetic recording media. 

Numerous studies have shown that these films can be grown in ways to produce a 

compositional inhomogeneous microstructure having Co- and Cr-enriched regions. 

The adclition of Ta. Pt to these media play an important role in determining the 

magnetic properties anti recording characteristics of the films. In order to better 

understand the beneficial roles of their addition, we have made SAS measurements 

on a variety of CoCrX (X=Ta or Pt) films deposited at ambient and 260 C substrate 

temperatures. Analysis of the Ta and Pt data indicates that no phase separation 

of the Pt or Ta atoms into clusters has taken place. Further analysis shows that for 

an increase in substrate deposition temperature, the average coorclination number 

decreases by 0.6 Co/Cr atoms. Figure 2 shows that, with the addition of Ta and 

Pt, the Fourier peak amplitudes of the Co EXAFS data decrease relative to that of 

the data for a pure CoCr film. The greater reduction in amplitude of the Fourier 

peaks when Pt is added than when Ta is added indicates that the Co environment 

is more disordered by the atldition of Pt than by the addition of Ta, suggesting a 

preferential site distribution of the Pt atoms to the Co atoms. 'KMK was supported 

by a National Res. Council/NRL Fellowship. Research also supported by the U.S. 

DOE, Office of Basic Energy Sci. k Office of Health & Environmental Res., contract 

No. SV-31-109-E11g-38. 


Figure 1. Fourier transformed Ta and 

Pt ESAFS data for the CoCrX (X=Ta 

or Pt) samples deposited at ambiek and 

260°C substrate temperatures. 


X23A2, 

X23B 

Figure 2. Fourier transforms of Co 

ESAFS data for the CoCrS (S=Ta or 

Pt) samples deposited at ambient and 

260" C. 

AZJAZ, 

Structure and Chemistry of FeSz Battery Cathodes * 

X23R 

E. Strauss, D. Golodnitsky, E. Peled (Tel Aviv U.) S. Kostov, hI. L. denBoer, and 

S. G. Greenbaum (CUNY, Hunter College) 

The Li/CPE/FeSZ battery (CPE = composite polymer electrolyte) is a promising 

candidate for energy storage and electric vehicle applications. Its projected specific 

energy is over 170 Wh/kg (based on 2.5 e/FeSz), and a recent small laboratory cell 

demonstrated over 300 full charge-discharge cycles. Using in situ x-ray absorption 

methods we have investigated the behavior of thin Li/CPE/FeSZ cells at various 

stages of charge and discharge cycles. Cells mere examined under the following 

conditions: (i) charged to 1.85 V and x = 0.5, where x represents the number of 

electrons associated with that particular charge state; (ii) charged to 2.05 V and x 

= 1.7; (iii) charged to 2.25 V and x = 2.0: (iv) discharged to 1.65 V and x = 1.4: 

(v) discharged to 1.25 V and x = 0.15, antl (vi) discharged to 1.1 V and x = 0.0. 

Regardless of whether the cell is being charged or discharged, there appear to be only 

two distinct Fe host environments, a "low-Li" one for conditions (ii), (iii) and (iv) 

and a dramatically different "high-Li" one for conditions (i), (v) and (vi). At high 

Li (cathode) concentration a strong pre-edge feature is apparent, which decreases at 

low Li concentration, as shown in Fig. 1.. This pre-edge feature is dipole-forbidden 

in octahedral symmetry. and its decrease therefore indicates that the symrnetry 

decreases as Li is removed from the cathode. The EXAFS similarly falls into two 

distinct categories (Fig. 2). At high Li concentration the Fe environrnerit is ordered. 

and analysis reveals a combination of nietallic Fe antl residual unreacted FeSz. On 

the other hand, at low Li disorder scts in and only a single broad peak is observed, 

analysis of which irltlicates a combination of FeS2 antl LizFeSz. Structural ard 

chcmical changes in the Fe environment appear to be highly reversible. 

2 4 6 

Figure 1. Kear-edge x-ray absorption O 

snectrum of cells under various char~e Spacing (Angstmms) 

L, 

conditions as described in the text. 

Figure 2. Fourier transform amplitude of 

representative low-Li and high-Li cath- 

* Supported by DOE Basic Energy otles. 

Sciences

4d 

h3 

0 

I XSW Determination of the S/Au Interface Structure in SAMs * I X24A 1 I X-rGstanding Wave Determination of Quantum Well Perfection I X24A I 

P. Fenter (Princeton U., & ANL), F. Schreiber and G. Scoles (Princeton U.), L. 

Berman (NSLS), P. Eisenberger (Columbia U.), and M. J. Bedzyk (Northwestern, 

& ANL) 

While it is widely believed that the S/Au interface structure in self-assembled 

monolayers (SAM) of thiols adsorbed on Au(ll1) surfaces consists of sulfur head- 

groups bound in the Au three-fold hollow site, a recent grazing incidence X-ray 

diffraction (GIXD) study[l] determined that the GIXD data were inconsistent with 

this model, and instead required a dimerization of the sulfur headgroups, with a 

sulfur-sulfur spacing of 2.2A. To further clarify the bonding in SAMs, we have used 

X-ray standing waves (XSW) in the back reflection geometry to determine the pre- 

cise sulfur headgroup positions in this system. Using XSW, we have measured the 

coherent fraction, f, and position, P for the (111) and (11-1) Au substrate reflections, 

from which we determine both the vertical and lateral headgroup location. We find 

that Plll=l.lOf 0.01, flll=O.4lf 0.01, Pll-l=O.25f 0.01, fll-l=-0.02f 0.01. These 

measured values are inconsistent with any model whict incorporates a unique sulfur 

bonding site, including the widely assumed three-fold hollow site. Making use of 

the monolayer symmetry (which incorporates two inequivalent molecules per unit 

mesh), we derive the full range of sulfur sites which are compatible with the XSW 

data (shown as dots in Fig. 1). These results clearly show that each sulfur head- 

group is located in distinctly different lateral and vertical sites with respect to the 

Au substrate lattice (large open circles): while one is located near the atop site at a 

height of 2.21zt0.05A, the other is found in an annulus surrounding the FCC three- 

fold hollow site at a height of 2.97f 0.05A. These results are consistent with the 

GIXD-derived S-S spacing of 2.2& and highlight both our limited understanding 

of bonding in these complex systems and the related need for quantitative struc- 

tural probes as the basis for our understanding. [l] P. Fenter, A. Eberhardt and P. 

Eisenberger, Science 266, 1216 (1994). 

Figure 1. 

* This work was supported by DOE grant number DE-FG02-93ER45503, and F.S. 

acknowledges the support of the DFG 

J.A. Gupta, E.D. Crozier, S.P. Watkins (SFU) J.C. Woicik, J.G. Pellegrino (NIST), 

and K.E. Miyano (Brooklyn College) 

We have used the x-ray standing-wave technique combined with high-resolution 

x-ray diffraction to determine the quantum-well perfection in monolayer InAs quan- 

tum wells grown on GaAs(001). Preliminary analysis from wells grown at 430, 480, 

530, and 580 degrees C find the most organized monolayer to be produced at 480 

degree C preceeded by a linear ramp from the 580 degree C buffer layer growth 

temperature. Apparently, In is desorbed from the growth surface at the higher 

temperatures, as determined from the ratio of the In versus GaAs fluorescence with 

the remaining In diffused into the cap. The 430 degree C growth results in a rough- 

ened buffer-layer/quantum-well interface.

tj 

c.3 

+ 

3 

X-ray Standing Wave Investigation of Hg/Ni(100) X24A X-Ray Standing Wave Measurements from a 5-Fold Symmetry Re- 

D. Heskett. J. Warner (Univ. of Rhode Island). L.E. Berman (NSLS-BNL), and flection in the Quasicrystal AlPdMn 

I I I 

PA. Dowben (Univ. of Nebraska-Lincoln) 

Terrence Jach (NIST), R. Colella (Purdue), A. I. Goldman. T. Lograsso. and D. 

Delaney (Ames Lab) 

We have used the technique of Back-reflection X-ray Standing Waves (BRXSW) 

to investigate the structure and geometry of mercury on the Ni(100) surface. We 

prepared these systems by dosing 12-24L of Hg onto the Ni(100) surface at room 

temperature, which resulted in one layer saturation of the surface. The dosing was 

then followed by an anneal to 80-100°C.. which resulted in the loss of = 25 % of 

the mercury, based on the intensity of the Hg 3cl core levels. This procedure has 

been previously shown to produce a well-ordered (2x2) overlaver LEED pttern.' 

\ire next performed x-ray standing wave measurements of this overlayer in both 

the (200) arid (111) Bragg reflection geometries. One set of data taken in the (200) 

geometry is presented in Fig. 1. Based on the high coherent fractions meas~~red 

In both geonwtries, we can conclude that the mercury atoms are very well-ordered 

both parallel and perper~tlicular to the Ni(100) surface. Based on triang~llation 

of the cohcrcnt positions from both sets of measurements, we can determine that 

the Hg atoms are bonded in four-fold hollow sites at a distance of 2.36&dxwc the 

(100) Ni planes. This result is in good agreerr~ent with a study of this system 

by Poulsen ct a1. using the technique of ion transnlission cl~anneling.~ On the 

other haritl. in conlparison to another XSW stutly of this system by Prirlce et nl.," 

a similar Hg-Ni(100) perpentliculnr spacing was obtained, howcver, they concl~~tletl 

that the Hg ato~ns were hour~tl in bridge sites. In that study, they had not perforn~ctl 

triangulatior~ rncasurements using a tlifkrent scattering geometry, which in ow case 

conclusively provcs hollow site ntlsorption. 

' R.G. ,Jones nntl A.iV.-L. Tong, S11rf. Sci. 188, 87 (19987). P.R. Poulsen, I. 

Stensgaartl, and F. Besenbacher. Surf. Sci. 310, L589 (1994). ' N.P. Prince. N.K. 

Singh. \V. [filter, D.P. \\.hotlruff, and R.G. .Jones, .I. Phys. Contlens. hIatter 1. 

SB21 (1989) 

. -~ I j 

n~ckel ---a 

coher pos = +.02!.01 i 

' coher frac = 88i 04 coher frac = 89 t.01 ' 

$3 W 

-2 1 0 1 2 

Relat~ve Energy lev) 

We have measured the diffraction peak and the x-ray standing wave in a 5-fold 

symmetry reflection from a quasicrystal. The [422222] reflection was observed in 

back reflection (BB = 90') in an energy scan from single-domain AlPdhIn around 

2860 eV. A1 Ka fluorescence observed during the scan displayed distinct x-ray stand- 

ing wave effects. The observation of x-ray standing waves demonstrates that the 

tlparnical theory applies to aperiodic media The fluorescence from XI is similar to 

that observcd from 2-fold symmetry reflections in that it appears to have a small but 

non-zero coherent position. This is evidently incor~sistent with a centrosymrnetric 

model for the quasicrystal. 

0, = 90'. Diffraction Energy Scan 

800 

700 _ (422222) Reflection . 

- 600 

500 - 

5 400. 

5 300 - 

. . 

0 ,. . -. . -. %.-.A 

. . 

. . 

-. 

. . re.. --. .'.& . . 

.+.?;. 

. .&-, . 

: 200 . . 

- 

100 - 

4e*4 AI Fluorescence , 

1 2et4 - 

1 oe.4 

5 eoe.3 

60e.3 

4 0et3 

2 0e.3 &-. - :+. 

0 0e-0 

--- 

2852 2851 2856 2858 2860 2862 24M 

Energy (eV1 

Figure 1. XS\\- measurements and simulations of the Hg 111- core level and Ni LlIlI 

.iuger yields for the system Hg/Si(100) in the (200) Bragg reflection geometry (top Figure 1. The .5-fold symmetn reflection (above) and -41 fluorescence (below) are 

curves). The bottom curves are the measured and simulated reflectivity. both shown after subtraction of a linear background.

Grazing Incidence X-Ray Photoemission Spectroscopy of SiOz/Si 

Terrence Jach and J. Gormley (NIST) 

XPS spectra were obtained with collimated incident radiation over a range of 

angles in the vicinity of the critical angle for total reflection. In addition to the 

general decrease in the penetration depth which accompanies incidence below the 

critical angle, the different optical constants of overlayers result in different critical 

angles. The x-ray fields in each layer change in a non- linear way at each angle 

and contribute in varying amounts to the photoemission. This allows for fitting the 

thickness and density of oxide overlayers on Si in a range of 1-lOnm. By performing 

the measurement on X-24A, using an InSb(lll)/KDP(lll) crystal pair, we have 

increased the yield by a factor of 100 over what was previously obtained from 

conventional x-ray sources. We operated in the vicinity of the Si K-edge (1839 

eV). We were able to obtain spectra above and below the edge. This allowed us to 

change the optical constants and observe the resulting effects in photoemission line 

intensities. 

10 A SiO,/Si GIXPS, Si 2p 

Figure 1. XPS lines from the Si oxide and bulk obtained for E=1820 eV. 

X24A 

I Argon Photoion Charge State Distributions I X24A I 

L. Pibida, R. Wehlitz, J. Levin, and I. Sellin (U. Tennessee at Knoxville) 

Using the single-bunch mode of the X-ray ring, we have measured the photoion 

charge state fractions after photoionization of argon atoms. The experimental setup 

consist of an ion time-of-flight (TOF) spectrometer, mounted on a XYZ translator 

together with a hypodermic needle that allow us to align it with respect to the 

photon beam. The TOF spectrometer was mounted perpendicular to both the 

photon beam and the electric vector of the monochromatized synchrotron radiation 

direction. When an Ar atom is photoionized (hv ,-., 3206.3eV) a cascade decay 

process can occur leaving the Ar ion in different charge states depending on the 

decay path that occur. The photoion charge state distributions depend on several 

experimental parameters as the voltage across the microchannel plate detector, the 

pressure in the experimental chamber, and the threshold of the constant fraction 

descrimintor used to process the signals. These measurements require a careful 

control of these parameters. After the optimum experimental parameters were 

determined we measured the photoion charge state fractions as a function of the 

photon energy. From where we estimated the fluorescence yield to be 0.115 f 0.02 

and the Auger yield 0.885&0.02. Several measurements of the photoion charge state 

distributions near the K-edge are available. From these measurements we saw that 

the value of charge state fractions are sensitive to the variation of the experimental 

parameters chosen. 

" 

--- 

A 

. XI' 

~r'+ 

- 

3 190 3200 32 10 3220 


Figure 1. Ion Charge state fractions as a function of the photon beam energy. The 

error bars are smaller than the size of the symbols.

4j 

bJ 

F 

bJ 

5 eV Atomic Oxygen Damage to Low Earth Orbit Optical Compo- 

nents 

J.C. Rife (NRL) 

We have initiated a study of the effects of 5 eV atomic oxygen (ATOX) bombardment 

on ultraviolet and soft x-ray optical surfaces. Typical ATOX fluxes for 

low earth missions such as the shuttle and satellite observatories are loz0 to loz2 

atoms/cm2-year in the ram direction. ATOX bombardment affects the top surface 

layers, and is not energetic enough to sputter practically all materials. However, 

ATOX can quickly erode hydrocarbon compolmtls and coatings such as osmium that 

form volatile oxides antl can also alter the oxide layers ancl the surface condition of 

other materials. 

\Ve have measured the reflectance of silicon and fused silica as well as Mo/Si. 

W/Si, W/B4C, and W/C multilayers before and after an ATOX dose of 10" 

atoms/cm2. Fig. 1 shows the 5 degree grazing reflectance at the oxygen K edge 

of bulk SiO2, a silicon wafer with typical native SiOz overlayer 1 nm thick, and an 

equivalent silicon wafer exposed to ATOX. Changes in the absorption edge structure 

of the dosed wafer indicate an increase in oxide thickness antl an admixture of 

oxygen-oxygen bonds antl other bonding states in the damaged oxide. 

t 0.01 6 

I 

5 deg grazing . . . . . . . 

Oxygen K edge 

J 

SiO, bulk 

------ Si wafer, oxide 10 Ang 

- Si wafer ATOX 

X24C 

I GaN: Grazing Reflectance XANES at the Nitrogen K Edge I X24C I 

J.C. Rife (NRL), W.R.L. Lambrecht, S.N. Rashkeev (Case Western Reserve U.), 

K. Lawniczak-Jablonsha: T. Suski (LBL), and D.K. Wickenden (Johns Hopkins U.) 

We have measured the 5 degree grazing reflectance of GaN in its anisotropic 

wurtzite form at the nitrogen K edge for linearly polarized light with Ellc and Elc. 

From Kramers Kronig analysis of the data and previous reflectance measurements 

from 2 eV to 150 eV, we have extracted the polarized absorption coefficient at the 

nitrogen K edge (see Fig.1). In addition. we have determined the Elc absorption 

by total photoyield at the ALS and the unpolarized absorption and reflectance by 

a first principles LDA band structure calculation at CiVRU. 

Energy location ancl shape of the spectral features for the nitrogen absorption 

derived from reflectance and the total photoyield are in good agreement. A 23.1 

eV shift to higher energies was required for the calculated absorption spectrum to 

match the measured one. The calculated spectrum reprocluces all the experirnen- 

tal features well, although the relative magnitudes of peaks vary somewhat. The 

good agreement of peaks and peak positions implies that the self-cnrrgy correction 

beyond LDA consists primarily of a constant shift up to about 10 eV above the 

conduction bantl minimum. This is in disagreement with GiV calclllations which 

predict increasing corrections for higher contluction bantl states. 

- I 

:, 

GaN polarized absorption. Nitrogen K edge. 

by KK analysis of 5 deg grazing reflectance 

. . 

: . d - F nar: 

ENERGY (eV) ENERGY (eV) 

Figure 1. Figure 1.

Characterization of Multilayer Coated Gratings and Mirrors I X24C 

J. F. Seely, M. P. Kowalski, J. C. Rife, W. R. Hunter, and R. G. Cruddace (Naval 

Research Laboratory) 

Diffraction gratings and mirrors with multilayer coatings are characterized in the 

soft x-ray and extreme ultraviolet regions. The multilayer coatings are designed to 

have high reflectance at wavelengths and angles of incidence that are important for 

the study of laboratory, solar, and astrophysical plasma emissions. The efficiencies 

of the multilayer coated gratings, and the reflectances of the mirrors with similar 

coatings, are measured as functions of the angle of incidence and the wavelength 

of the incident light. The measured reflectance is compared to model calculations 

that account for the layer thicknesses, interfacial roughness, interdiffusion layer 

thicknesses, and the optical constants of the layer materials. The gratings have 

blazed or laminar groove profiles and are fabricated by the holographic ion-beam 

etched process. The multilayer coating is matched to the groove profile so that the 

coated grating has optimal efficiency at the angle and waveband of interest. The 

measured grating efficiency is compared to the efficiency calculated by a computer 

code that rigorously models the diffraction process. Multilayer gratings are being 

developed for a rocket spectrometer that will study the extreme ultraviolet radiation 

from a white dwarf star. Multilayer mirrors are developed for normal-incidence 

microscopes that image the soft x-ray emissions from laser-produced plasmas with 

extremely high spatial resolution. 

I Structure of Supercooled Liquid Silicon I X25 I 

Stuart Ansell (Argonne National Laboratory), Shankar Krishnan, John J. Felten 

(Containerless Research, Inc.) and David L. Price (ANL) 

We report X-ray diffraction measurements of the structure factor S(Q) and the 

radial distribution function G(r) of levitated liquid silicon in the stable and super- 

cooled states. Supercooling results in a sharpening of the first peak in S(Q) and a 

shift to an 8% higher Q value, the appearance of a double shoulder on the high-r 

side of the first peak in G(r), a sharpening of the first peak in G(r) and a decrease 

in coordination number. These changes are consistent with a significantly enhanced 

degree of covalent bonding. 

S. Ansell, et al., in Press, J. Phys. Cond. Matt., 1997.

Characterization of Mn Oxidation States in Photosystem I1 by X-Ray 

Fluorescence Spectroscopy 

X25 

U. Bergmann (LBNL). C. R. Horne (LBNL, UC Berkeley). S. P. Cramer (LBNL 

and UC Davis), P. DeMarois ancl J. Penner-Hahn (U. of Michigan) 

The generation of atmospheric oxygen through photosynthetic water-oxidation 

is one of the most fundamental processes responsible for the existence of aerobic 

life forms on earth. The reaction is catalyzed by an oxygen evolving cluster (OEC) 

located in photosystem 11. which contains 4 hln ions. The catalytic mechanism is 

proposed to involve 5 intermediate states callecl the S states of the Kok cycle. In 

each of the first 4 steps (SO to S4) a photon is absorbed and the OEC is assumed 

to be singly oxidized antl in the last step (S4 to SO) the oxygen is released. Despite 

numerous studies over the last 10 years, a controversy about the 1In oxitlation states 

has remained to (late, antl this information is crl~cial for the full understanding of 

the water osiclation. Using the technique of high resol~~tion X-ray fluoresccncc 

spectroscopy, we studied the hIn-oxidation states in two S1-states of photosystem 

11. Fits of the K-beta x-rv e~nissiori spectra with that of nrotlel cornpo~mds arc 

consisterrt with the following models: 1.) The S1 state of photosystem IS contains 

1In(III)211r1(IV)2. 2.) In the hytlroclui~~one-treatetl S1 state the hIrr(III)2 is retlucecl 

to hIn(I\')2. The first res~dt confirms orre of the currently proposed models. antl the 

secorltl result reveals new information about the chemistry irrvolvetl in the creation 

of the OEC. The results demonstrate the potential of this spectroscopic technique. 

which is con~plementarv to the tcchniq~~es of XAS antl EPR. The study of other 

S-states of plrotosysern 11 is proposed for the future. 

Evaluation of Efficacy of New Fixed-Wavelength X25 Side Station I X25 I 

L.E. Berman and Z. Yin (NSLS) 

The X25 and X21 hybrid wiggler magnets each radiate a photon fan spanning 

5 horizontal mrad (at 2.5 GeV). of which the central 3 consist of useful hard x- 

rays. For the most part, however, the existing X25 ancl X21 beam lines make use 

of no more than the central 1 mrad, containing the brightest x-ray photons. and 

consequently most of the horizontally off-axis radiation is unused. 

The properties of the horizontally off-axis radiation of the X25 wiggler source 

were studied, in an effort to determine the efficacy of adding a new S2.5 (or X21) 

experimental station that would sit aide the existing beam line and make use of 

the presently unusecl off-axis photons. In order to make best use of existing floor 

space, antl provide ample enough separation from the present bean1 line. the optics 

of a new beam line to support such a station ~voultl most likely be based upon 

a horizontally-focussing. sitlemays-diffractitig bent single crystal monochromator. 

delivering a fixed wavelength to the station. A subsequent bent mirror codd focus 

the beam vertically anti rqject harmonics. Such a. station could well support a 

fixed-wavelength crystallography program. which constitutes a large fraction of the 

demand for the existing X25 station. 

There are two handicaps that such a "sitle station" would suffer, compared with 

the existing "central station". First, the viewed ratliatiorr spectrum is softer because 

the radiation gets emitted from the gent,ler-curving segrnerrts of t h wiggler ~ trlagrlct 

instead of thc tightly-curving ones. This is shown in Fig. 1, which tlisplays the 

rneasurcd X25 wiggler spectrunl as a furrction of horizorital angle across the ratliation 

fan. Second. the wiggler magnct poles, as viewed Frorn a "sitle station", do trot line 

lip (as th~y ~v0111(1 ~vhen vicnwl from the "cmtral st,ationW), and conseq~~ently t,he 

viewed horizoutal source is broatlenetl in proportion to the length of tlrc wigglrr 

magnct. This is shown ill Fig. 2. which displays t,he rrleasl~retl Irorizo~~tal source 

sizc as a fi~rrction of horizo11t:d angle across the ratliation fan. It is corrclutletl that 

a rrew '.side station'', whose central ray is horizontally off-axis by 1 nrratl (which is 

feasiblc to pursue), could tlcli\rcr a rnonoclrrornntic photon intrnsity that is abont 

50% of that available in the existing "central station" (based, for instance. on similar 

optics) at 8 keV, antl about 40% at 12 key. 

5 10 15 

Energy (keV) 

Figure 1. The photon energ spectrum. 

measured as a function of horizontal an- 

gle across the SE.5 n-iggler fan. is shown. 

10 

1 5 -0 5 0 5 15 

Hor~zontal Angle (mradl 

Figure 2. The horizontal source size. 

measured as a function of horizontal an- 

gle across the S25 n-iggler fan. is shown.

2 

U1 

I Characterization of New X25 Double Multilayer ~onochrorn&o-I 

L.E. Berman, Z. Yin (NSLS), S.G. J. Mochrie, and O.K.C. Tsui (MIT) 

The X25 monochromator has been capable of accomodating a pair of multilayer 

elements since early 1995. This has been especially useful for x-ray scattering and 

emission experiments for which high monochromaticity is unnecessary, but high 

intensity is. A multilayer monochromator has about a 100 times broader band- 

width than a silicon monochromator, and thereby can deliver 100 times as much 

"monochromatic" intensity to the experiment. 

The X25 multilayers are each composed of tungsten-boron-carbide (W/B4C) mul- 

tilayer films grown on silicon substrates, and purchased from Osmic, Inc. of Troy, 

Michigan. Recently, a new pair of (W/B4C) multilayer elements, each with a d- 

spacing of 25 A, was obtained. the new pair has a 30% narrower bandwidth than 

the original pair. The photon energy dispersion function of the new pair was mea- 

sured using a Si(ll1) analyzer crystal, and is shown in Fig. l. Its main peak has 

a relative FWHM of 1.1%. The side fringes about the main peak arise from the 

finite number of bilayers (120) in the multilayers. The calculated reflectivity curve 

for this multilayer pair, based upon its fabrication parameters and assuming ideal 

interfaces, is shown in Fig. 1. A better agreement of theory and experiment can be 

obtained by assuming that an interdiffusion thickness, between layers, was present 

with a u of 4 A, as also shown in Fig. 1. 

The efficacy of improving the resolution of the multilayer pair, via angular mis- 

alignment (from parallel) of the two elements with repsect to each other, is demon- 

strated in Fig. 2, which shows the measured dispersion functions for different mis- 

alignment angles. A misalignment angle of 1 arcmin reduces the relative FWHM 

to 0.9%. The main peak sharpens further upon introduction of a 2 arcmin mis- 

alignment. However, the neighboring side fringes become comparable in intensity 

with the main peak in this case, thereby compromising the objective of resolution 

narrowing. 

0.60 1 /' 

'i calculation with no mterd~llusion 

, - 

0.20 , . 

- 

+, ,. 

, . b* ', 

,", : . ' 

J . , 

, , , . '.., 

0.00 - ' 

8800.0 8900 0 9000.0 9100.0 9: 


Figure 1. The measured double multilayer 

dispersion function at 9 keV (dotted 

curve) is compared with theory, for 

the ideal case of no interdiffusion at the 

interfaces (dashed curve) and for the 

case of an interdiffusion thickness with 

a u of 4 A(so1id curve). 

.-----a -3 ----- -,-.----.\. 

0 -- 

8800.0 8900.0 9000 0 9100 0 9: 


Figure 2. The measured multilayer dis- 

persion functions at 9 keV are shown for 

the cases of no misalignment of the mul- 

tilayers (solid curve), a misalignment an- 

gle of 1 arcmin (dashed curve), and of 2 

arcmin (chain-dashed curve). 

I Mechanistic Studies of Rat Liver F1-ATPASE 1 ~ 2 1 5 

M. A. Bianchet, J. Hullihen, P. L. Pedersen, and L. M. Amzel (Johns Hopkins U.) 

F1-ATPase is the soluble portion of the FIFO-ATP synthetase complex, the pro- 

tein that carries out the synthesis of ATP in the mitochondria. F1 by itself exhibits 

a Mg++ dependent ATP hydrolytic activity. Crystals of rat liver F1-ATPase were 

obtained using (NH4)2S04 as a precipitant in the presence of ATP, Pi and in the 

absence of Mg. Under the crystallization condition used, rat liver F1-ATPase is 

known to be active. F1 from redissolved crystals has all subunits and hydrolyzes 

ATP with full activity when Mg++ is added. The three dimensional structure of the 

rat liver F1-ATPase was determined to 2.8 A resolution using these crystals. The 

more symmetrical conformation of the a- and P-subunits observed in the rat liver 

F1 vis-a-vis the bovine heart enzyme [I] suggests that it may be in another stage of 

the proposed mechanism or perhaps suggest a different one. A new crystallization 

condition, without phosphate buffer, allows crystals be formed with Mg present in 

the crystallization media. Cocrystals of FI-ATPase with MgAMPPNP (non hy- 

drolyzable analogous to ATP), MgADP.Vi (analogous to the transition state) and 

MnADP allow the study of different states in the hydrolisis/synthesis of ATP. Data 

obtained from these three co-crystals at NSLS ( X25 beam line) are being analyzed 

at the present time. 

1.- Abrahams et al. Nature 370, 621-628 (1994).

Crystallographic Studies of Hin Recombinase DNA-binding Domain 

Bound to Different Binding Sites. 

T. K. Chiu, D. Cascio, R. Johnson, and R. E. Dickerson (UCLA) 

X2 5 

Hin Recombinase belongs to a family of proteins that catalyses site-specific DNA 

inversion in enteric bacteria. This family includes Gin from phage RIu. Cin from 

phage PI, and Pin from phage e14. Hin recognizes a binding site which consists of 

a highly conservecl inverted repeat of 12bp (consensus sequence : A/T G G T T T 

A/T G G A G/T A A) separated by a central 2 bp 'core.' The crystal structure of 

a 52 amino acid pepticle consisting of the DNA-binding-domain of E.coli Hin bound 

to the hixL half-site tGTTTTTGATAAGAlaTCTTATCAAAAAC has been solved 

(Feng et al. Science '94). Two water molecules were observed to mediate contacts 

between Hin ancl its binding site ancl were proposed to be crucial for Hin's site- 

specific recognition. In order to further characterize this recognition process, we 

have co-crystallized the Hin Recombinase DNA-binding domain bound to different 

mutant binding sites, and have collected synchrotron x-ray clata at beamline X25 

on seven different co-crystals. These crystals are isomorphons (six in space group 

C2221, with a= 86, b= 82, c= 44; and one in space group C2221, with a=67.5, 

b=69.7, c=63.6) but diffract to different a extent, with the best one diffracting 

to 2.2A antl the worst one diffracting to 2.9A. Crystallographic refinement antl 

structural analysis are in progress. 

OspA-LA2 Fab Complex Structural Study with Molecular Replace- 

X25 

ment Methods 

W. Ding, B.J. Lufts, X. Yang (SUNY at Stony Brook), J. J. Dunn, and C.L. 

Lawson (BNL) 

Lyme disease is a progressive infection resulting from inoculation of the spirochete 

Borrelia burgdorferi into the skin by a feeding tick. OspA (Outer Surface Protein 

A, 31 kDa) has been shown to be present when the spirochete is dormant in the tick 

midgut but is no longer detected after rapid division and dissemination to the tick 

salivary glands during a blood meal. This may explain why the natural immune 

response to OspA develops only in a minority of Lyme disease patients.and usually 

only late in the course of the disease. Studies have shown that vaccines based on 

OspA can induce protective immnnity in mammals. Blockage of spirochete transmmison 

from the tick vector to the mammalian host by anti-OspA antibodies appears 

to be the main mechanism of the protection. However,the protection appears to 

be serotype specific. In murine vaccine studies, the protection mas conferred only 

when hamster's immune response was directed to the epitope defined by the mAb 

LA2. A three dimensional strncture of the protein conlplex of OspA and LA2 Fab 

will be essential to exactly defining the protective epitope antl elucidating protein 

function. It will provide the invalnable aid in rational vaccine design. 

Crystals of the OspA-La2 Fab complex were grown at 4OC by hanging-drop 

vapour diffusion methods (0.lhI Na Cacotlylate, O.lhI Na Acetate antl lOPEG 3300 

at pH 6.15). They belong to space group P21212, with unit cell dimension a = 

99.5 b=129.5 c=l44.5. Diffraction tlata were collected at the National Synchrotron 

Light Source, on the beamline X25 ming hIAR image plate/scariner systems. The 

tlata included 194789 observations of 51741 nniqne rcflcction, R,,,,,,,, = 0.048, representing 

98% of the observable clata to 2.4 A resoultion. There are two protein 

complex molecules in a asymmetric unit. 

hIolec~~lar replacement method was attempted with the tlata set to determine the 

orientation antl position of LA2 Fab in the crystal lattice. Although the amino acid 

sequence of LA2 is at present only partially known. the honiology to lgaf is expected 

to be highest in 17 high resolution Fab structures from the protein tlata bank by 

sequence alignment. The n~olecular replacement program XPLOR (Brnnger, 1992) 

was ~mployetl to perform search with the constant plus variable tlornain of the Fab 

as a motlel. The elbow angle was modified with the inter~al of 5". The motlel with 

elbow angle of -20" yieltletl consistent solutions in each resolution shell. The direct 

space Patterson search method (Hnber, 1985) was employed for roatation search 

comprised 15 to 4 A resoultion clata. PC-refinements were carried out where the 

search model was oriented to each of the 191 potential peaks. The first and second 

peaks gave the potential solution jndged by high correliation coefficient. XIolecule 

A was subjected to a translation search with a sampling interval of 1X in each 

tlin~ension. The position of molecule B was tletermined by keeping molecule A fixed 

to solve the ambiguity on the cell origin. The initial motlel was refined by the rigid 

body refinement antl enerp minimization. The refined R factor is 0.33. The motlel 

is cross validated by the difference Fourie map calcnlatecl with the protein phase. 

The electron design map is being interpreted with building Osp.4 model.

Three Dimensional Structure of a Human Natural Killer Cell Inhibitory 

Receptor at 1.7A Resolution I x25 I 

Q. R. Fan, L. Mosyak, D. C. Wiley (Howard Hughes Medical Institute), C.C. 

Winter, N. Wagtmann, and E. 0 . Long (National Institute of Health) 

Killer cell inhibitory receptors (KIR) on human natural killer (NK) cells prevent 

the lysis of target cells bearing specific class I MHC molecules. The human p58 KIR 

clone 42 recognizes HLA-Cw4, -Cw2, -Cw5 and -Cw6, but not HLA-Cw3, -Cwl, 

-Cw7 or -Cw8, which are recognized by p58 KIR clone 43 l. 

We have determined the X-ray structure of a p58 KIR (p58-c142) at 1.7A resolution 

using multiwavelength anomalous diffraction (MAD)' method. MAD data of 

a single selenomethionyl p58-c142 crystal (hexagonal rod with dimensions of 0.06 x 

0.06 x 1.5 mm3; P61; a=b=92.3A c=47.0A were collected to 2.2A with a 300 mm 

diameter MAR Research image-plate system at X25 beamline of the National Synchrotron 

Light Source, Brookhaven National Laboratory. MAD phasing was treated 

as a case of multiple isomorphous replacement3; refinement of anomalous scatterer 

parameters and phase calculation were performed with MLPHARE4. The initial 

MAD map was improved by density modification using DM~, assuming 40% solvent 

content. A model of ~58442 KIR was traced from both the density modified and 

unmodified electron density maps. A high resolution native data set was collected 

to 1.7A on the Princeton 2K CCD detector at F-1 beamline of the Cornell High 

Energy Synchrotron Source (CHESS). The atomic model has been refined against 

the native data at 1.7W resolution to a crystallographic R-value of 20.6% (Rfree = 

25.4%). 

The p58-c142 KIR structure has tandem immunoglobulin-like domains positioned 

at an acute, 60' angle. Loops on the outside of the elbow between the domains 

form a binding site projected away from the NK cell surface. The topology of the 

domains and their arrangement relative to each other reveals a relationship to the 

hematopoietic receptor family, with implications for the mechanism of inhibition in 

NK cells. 

/ I 

1 Long, E.O., et al. Immunological Reviews, 155, 135-144 (1997). 

2 Hendrickson, W.A., Science 254, 51-58 (1991). 

3 Ramakrishnan, V. Biou, V., Methods in Enzymology, 276, 538-557 (1996). 

4 Otwinowski, Z., Isomorphous replacement etc., (Science & Eng. Res. Council, 

Daresbury Laboratory, Daresbury, UK, 1991). 

[5] The CCP4 suite: Programs for protein crystallography. Acta Crystallographica 

D50, 760-776 (1994). 

I Structural Studies Of Type I DNA To~oisomerases I X25 I 

H. Feinberg and A. Mondrag6n (Northwestern U.) 

DNA topoisomerases are proteins responsible for controlling and maintaining the 

topological state of DNA in the cell. They have been found in all cell types of both 

eukaryotes and prokaryotes and additionally in some viruses. They are involved in 

DNA replication, transcription, and genetic recombination. Four topoisomerases 

have been identified in E. coli topoisomerase I, gyrase or topoisomerase 11, topoi- 

somerases 111, and IV. Our work is concerned with type I topoisomerases, which 

include topoisomerase I and 111. The long term goal of our work is to understand 

in atomic detail the catalytic mechanism of these enzymes, including the protein- 

DNA interaction, the cleavage and religation reactions, the strand passage, and the 

conformational changes that occur during the topological manipulations. 

We have crystals of a 30 kDa fragment of E. coli DNA topoisomerase I. This 

fragment represents the region that we have speculated that it moves away from 

the rest of the protein during the topological transformations. The 30 kDa fragment 

contains the active site tyrosine and has cleavage activity. We have been unable to 

solve this structure by Molecular Replacement or MIR methods. In order to solve 

the structure, a four wavelength MAD experiment was conducted at X25 using a 

MAR CCD detector. For the MAD experiment a platinum heavy atom derivative 

with two sites per molecule was used. The crystals are monoclinic so 360' of data 

were collected per wavelength in lo oscillation steps. A total of 1440 frames were 

collected in less than 24 hours. The experiment was only feasible thanks to the 

availability of the MAR CCD detector. The data are excellent and the two sites 

are clearly visible in an anomalous Patterson. MAD phasing is in progress.

tj 

P3 

r 

Co 

Crystallographic Studies On the Nudix Proteins: Platinum Derivative 

of E.coli dATP Pyrophosphohydrolase * 

X25 

S. B. Gabelli. hI. A. Bianchet. S. F. O'Handley. 11. J. Bessman. L. hI. Xmzel. 

(JHU) 

The E.coli dATP pyrophosphohydrolase is a novel nucleoside triphosphate 

pyrophosphohydrolase which catalyses the hydrolysis of dATP to produce 

clAhIP ancl PPi. The enzyme contains the conserved signature sequence 

GXVEXXETXXXXXXREVXEEXXI that characterizes the "nudix hyclrolases". 

This family of enzymes hydrolyze nucleoside diphosphates linked to different moieties. 

X. This conserved sequence was previously referred as the i\IutT pattern. 

Crystals suitable for x-ray crystallographic studies have been grown by vapour 

diffusion antl microseeding. The crystals grow in arn~nonium sulphate and lcrystals 

were soaked in platinum chloride for 72 hours. They are orthorhombic antl diffract 

to 2.8A resolution. X mixture of 35glvcerol with artificial mother licl~~or was used as 

cryoprotectant. Data have been collected urltler cryogenic conditions at bcanllirie 

X25 at BNLS at a distance of crystal to tletector of 225m1n, 2 dcgrcc oscillatiou. 

using the 100 rnicrorl slits and 1.1X radiation. 

Crystallographic Studies on the Nudix Proteins: The Gene Product 

of the E.coli Orf209 * I x25 

S.B. Gabelli, h4. A. Bianchet, S.F. O'Handley. hl. Bessman, L. Mario Amzel (JHU) 

The nudix hydrolases are a family of phosphoanhydrases that carry out 

the hydrolysis of a nucleoside diphosphate linked to several different moieties. 

Across species, the members of the family contain the consensus sequence 

Gx~Ex~ExYxY.YxREV~EE~XI. This sequence appears to be a versatile nucleotide 

binding ancl catalytic site. Among family members, the gene product of E.coli 

ORF209, is an enzyme highly specific for ADP-sugars, with its highest activity on 

ADP-ribose. It catalyzes the hydrolysis of the pyrophosphate linkage: ADP-ribose 

< hhIP+ribose 5-P. Crystals of Orf209 have been grown by vapour tliffi~sion at 18 

C using polyethylene glycol as the precipitant. Initial data to 2.9 A resolution were 

collectetl on an image plate using a copper rotating anode. Higher resolution native 

tlata were collected at beandine X25 at BNLS with 1.1A radiation, using flash 

frozen crystals with 40the crystal to dectector distance was 225mrn and 100 micron 

slits mere used. The crystals are orthorhornbic, a=GG.DA, b = G7.8A, c=98.07A and 

diffract up to 1.9A so 345 rnm frames were used. The data have been intlexcd using 

DENZO, processed using SCALEPACK and the CCP4 suite. In addition, data 

from a crystal soaked for 72 hours on 11nh[ K2PtC14 were collectd at a crystal 

to detector distance of 225 mm, using 1.1X ratliation with 100 microns slits. The 

crystal had an orthorhombic cell, a=(i(i.GA, b = 68.1A. c=YG.05A and tliffracterl np 

to 2.9,4 so 180m111 frames with 150pixels were used. The tlata have bren prorcssctl 

using DENZO, SCALEPACK antl the CCP4 suite. 

Crystal Resolution Reflections Data completeness % Rsym%

Structure Of a Cre Recombinase-DNA Site-specific Recombination 

Synapse 

F. Guo, D. N. Gopaul, and G. D. Van Duyne (U. of Penn.) 

X25, 

X4A 

Cre recombinase catalyzes the reciprocal exchange of DNA strands between 34- 

base pair loxP sites during site-specific recombination. Using diffraction data mea- 

sured at the X25 and X4A beamlines, we have determined the 2.4 A crystal struc- 

ture of a covalent intermediate in the Cre-loxP reaction, where the recombinase 

has cleaved and formed 3'-phosphotyrosine linkages to its DNA substrates. Four 

recombinases and two DNA substrates are arranged in a pseudo-fourfold symmetric 

tetramer that represents a site-specific recombination synapse. 

Parent data and two heavy atom derivative data sets for this structure were 

measured at the X25 beamline. One derivative was made from selenomethionine- 

substituted Cre recombinase, with 22 anomalous scatterers in the crystallographic 

asymmetric unit. Data were measured at a single wavelength corresponding to a 

maximum of f" and the resulting anomalous diffraction signal led to strong crys- 

tallographic phasing power. The second heavy atom derivative made use of an 

iodine-containing DNA substrate. The selenomethionine derivative was also used 

for a three-wavelength anomalous diffraction measurement at the X4A beamline. 

Together, the heavy atom diffraction data from the two beamlines led to a readily 

interpretable image of the electron density. 

The Cu~a:,, Hypersatellites and Correlated Hypersatellites* 

X25 

K. Hamalainen, S. Huotari (Helsinki U., Finland), C.C. Kao (NSLS) and M. 

Deutsch (Bar-Ilan U., Israel) 

The hypersatellites (HS) and correlated hypersatellites (CHS) originate in transitions 

from an initial state having two K holes. Their theoretical intensities in Cu 

are, respectively, and lop6 of the Kal~ lines. To date, only a single resolved 

HS measurement exists. Even there, the at line is masked by the overlaping 

WLaz line, and a CHS intensity 5000-fold larger than theory is reported. 

The measured HS spectrum is shown in Fig. 1. The well-resolved components 

show the typical asymmetry of all 3d transition metal lines, indicating significant 

contributions from 3d spectator hole transitions. They are considerably broader 

(-7.5eV) than the diagram lines (-3eV), and their separation (-24eV vs. 20 eV) 

is also larger. 

Setting the anlyzer energy at the KC& peak and scanning the monochromatic 

excitation energy yields the HS threshold at 18,380f 30 eV (Fig. 2). This agrees 

well with both the Z+l approxiamtion (18,380 eV) and our Dirac-Fock calculations 

(18,400 eV). The intensity rise from zero supports the theoretical prediction of a 

pure shake-off nature of inner-shell shake processes. The slope change at -18.6 keV 

may indicate, however, contributions from yet-unspecified additional modes. 

Finallv, no indication was found for the CHS lines, to within

J 

b~ 

3 

Resonant X-ray Magnetic Scattering From an Fe/Gd Multilayer 

H. Hashizume, N. Ishimatsu, 0. Sakata (Tokyo Inst. of Tech., Japan), N. Hosoito 

(Kyoto U., Japan), T. Iwazumi (KEK, Japan), K. Namikawa (Tokyo Gakugei U., 

Japan), and L. Berman (NSLS) 

The competing Zeeman and exchange interactions, combined with the distinct 

thermal coefficients of the Fe and Gcl moments, produce various magnetic structures 

in thin-film Fe/Gd multilayers in an external field. In the aligned states, the Fe 

and Gd spins are parallel or antiparallel to the applied field. These are reversibly 

changed. by altering H or T, to the twisted states in which antiferromagnetically 

coupled Fe and Gd spins make large in-plane angles to the in-plane field. The phase 

change is expected to be sensitive to the charge ancl magnetic structures of the layer 

interfaces. In preparation to explore the spin structures of the Fe/Gtl interface, we 

have measured resonant X-ray magnetic scattering from a 15[Fe(3.5nm)/Gd(5.0nm)] 

rnultilayer on a silicon substrate using a circularly polarized beam. The X-ray energy 

was tuned to the Gd L3 edge antl a diamond (100) crystal was used to convert 

the linear polarization of the X25 wiggler beam to a left circular polarization. A 

flipping magnetic field of 2.j kOe was applied parallel to the sample surface antl 

either parallel (SJ=O0) or perpendicular (d=9OC) to the plane of scattering. The 

sum intensity If + I- in Fig. I stlows the charge Bragg peaks of lowest four orders. 

observed in specular scans at room temperature. The difference signal I+ - 1- , 

arising from the resonant rnagnetic-charge interference scattering, shows marked 

Bragg peaks of alternating signs in the i=9O0 configuration, while they are absent 

in the geometry. \Vhile this confirms an aligned state, simulations suggest that 

larger magnetizations are iritlucetl in the near- interface region of the paramagnetic 

Gd lavers than at the film centers. 

2nd 3rd 4h 3rd 4h 

1 I 

4 - 

* lo- + 1w . - 

.lL .lK 

9 001 , 091 - 

I 0 0 

t -091 

- 401 

X25 

Figure 1. Charge (I' + I-) and resonan magnetic-charge interference (IA - I -) 

Bragg peaks observed in a specular scan on a 1.5[Fe(3.5nrn)/Gd(5.0mn)] ~nultilayer 

at the Gd L3 edge. The applied field is parallel to the plane of scattering in (a) and 

perpendicular in (b). 

2.1 A Structure of the Complex Between Active Ras and The Ras- 

Interacting Domain of an Effector RalGDS 


~25, 

X12B 

The structure of the complex bewteen oncogenic protein Ras and the Ras- inter- 

acting domain of RalGDS (RalGDS-RID) has been studied by x-ray crystallogaphy. 

The structure of the complex will provide crucial information on Ras' interaction 

with its binding partner at an atomic level. Since the mutant forms of Ras are 

involved in 30% of human cancer and Ras' function is carried out through its effec- 

tors, the spatial location of the key interface residues may assist in identifying small 

molecules that are capable of disrupting this interaction and thus provide insights 

for the developnlent of anti-cancer drugs. A 2.8 room temperature data set on a 

native complex crystal mas initially taken at BL X12B. which enabled us to solve 

the structure. A 2.0 frozen data set was later taken at BL X2.5 in september, which 

enabled us to refine the structure to a much higher resolution so that we can see the 

side chain interaction more clearly. The crystal has a. P212121 space group, with 

a=75.648, b=78.256, c=87.313 . The complex crystallizes as a heterotertramer with 

two active Ras molecules ancl two RalGDS-RID subunits. 

Figure 1.

I Structural Studies of the IgE Fc Receptor I x25 1 I The Structure of Liquid Boron I ~ 2 I 5 

T. Jardetzky (Northwestern U.) 

S. Krishnan (Containerless Research, Inc.), J. J. Felten (CRI), S. Ansell, K. J. 

We are studying the structure of the high affinity IgE receptor that is involved Volin, and D. L. Price (ANL) 

triggering immediate type hypersensitivities such as allergic reactions. In the past 

year we have used the NSLS X-25 beamline to study two weakly diffracting crystal 

forms of the extracellular domains of this receptor. Our first trip in March, 1997 

focused on a derivative search for a tetragonal crystal form (P41 or P43), which 

diffracts to a maximum resolution of ~3.6 Angs. During this trip we used a new 

MarCCD detector which allowed us to collect 9 different data sets (1 native and 

8 potential derivative). Optimal wavelengths for the collection of anomalous data 

were selected by taking EXAFS scans from metal-soaked crystals. These data were 

processed and compared to the native data. Although significant differences in 

intensities were measured for the derivatives compared to the native data, nonisomorphism 

problems have prevented the successful interpretation of difference 

patterson maps. 

On our second trip to X-25 (September, 1997), we collected seven datasets on a 

new hexagonal crystal form of the receptor, which diffracts to -3.2 Angs using synchrotron 

X-ray sources. These crystals do not suffer from the same non-isomorphism 

problems as the tetragonal form. During this visit to X-25, we were able to collect 

two datasets from mercury soaked crystals of a cysteine mutant of the receptor, 

which show intensity changes when compared to the native protein. In addition, 

we were able to collect four data sets from heavy atom soaked wild type protein 

crystals. Tentative heavy atom solutions to the difference pattersons have been 

identified and are being further evaluated at this time. 

We report the first measurements of the structure factor, S(Q), and the pair 

distribution function, g(r), for pure liquid boron, in the temperature range 2600- 

2000K, in the normal and metastable (supercooled) liquid states. The S(Q) data 

show a weak feature at 2.5 k1 that resembles the first sharp diffraction peak. The 

first four peak positions in the g(r) for liquid B occur at 1.78, 3.16, 4.61, 5.98A 

respectively, and agree well with the corresponding positions in the g(r) for solid 

P-rhombohedra1 boron (B105). Supercooled liquid B shows considerable sharpening 

and narrowing of the peaks in the g(r) and is indicative of increased ordering of 

boron atoms. The similarity in the peak positions relative to solid &boron, a 

coordination number of about 6, combined with the known stability of boron's 

covalent bond shows the retention of icosahedral BIZ units in the liquid state. The 

number of such icosahedral clusters appears to increase as the liquid is supercooled. 

The results are discussed in relation to available data on the properties and structure 

of liquid and solid boron. 

S. Krishnan, et al., To be Submitted to Phys. Rev. B., 1997.

tj 

I9 

IQ 

t 9 

Levitation Apparatus for Structural Studies of High Temperature 

Liquids Using Synchrotron Radiation 

X~B, 

X25 


Research, Inc.), hI. A. Beno. S. Ansell. and D. L. Price (ANL) 

A new levitation apparatus coupled to an synchrotron-derived x-ray source has 

been developed to study the structure of liquids at temperatures up to 3000K. The 

levitation apparatus employs conical nozzle levitation using aerodynamic forces to 

stably position solid antl liquid specimens at high temperatures. A 270 Watt, COz 

laser was used to heat the specimens to desired temperatures. Two optical pyrometers 

were used to record the specimen temperature, heating curves and cooling 

curves. Three vitleo cameras antl a vitleo recorder were employed to obtain 

and record specimen views in all three dimensions. The levitation was 

supported orr a three-axis translation stage to facilitate precise positioning of the 

specirnen in the synchrotron radiation beam. The levitation system as erlclosetl in 

a vaclinm chamber with Be windows, connections for vacuum and gas flow. ports 

for pyromctrg. xritleo antl pressure rneas~~rements. The wcu~uri system inclucletl 

alrtornntic pressure control and multi-channel gas flow control. A phosphor screen 

couplccl to a high-resolution vitleo microscope provitletl images of the x-ray beam 

and specimen shatlom which were used to establish the spccirrlen position. The 

letritation apparatus was integrated with x-ray tliffractometcrs locatctl at X6B and 

X25 1)e;~mlincs at the National Synchrotron Light Sonrce. X-ray structural rneaswements 

have been obtained on a nlrmber of materinls including i\lnO:r, Ni, Si, 

CA, and other metallic arid cerarnic rrlaterials in the liqnitl statc. 

S. Krish~ian, ct al., Rev. Sci. Inst~~~m. 68, p. 3512 (1997). 

I Resonant Exchange Scattering in a Co/Ir Superlattice I ~ 2 1 5 

- 

hI. B. Salamon and K. O'Donovan (U. Ill.) and E. Kita and H. Yanagihara (U. 

Tsukuba. Japan) 

The goal of this experiment was to detect the magnetization density induced 

in the Ir spacer layer of a Co/Ir superlattice by mean of exchange resonant x-ray 

scattering at the LJJJ edge of Ir. To this end, several superlattices mere grown using 

rnolecular beam epitaxg, tuned to give antiferromagnetic coupling of successive Co 

layers. Owing to i~lstabilities in the storage ring tluring the first 2+ days of the run, 

only one sample could be examined. In order to separate magnetic dipole scattering 

from the charge-scattering satellites of the superlattice, the A(333) Bragg peak was 

used in the Illinois polarimeter in the o-.ir configuration. Nlrmerous adclit~orial peaks 

were detected at posit,ior~s in reciprocal space that were indcxible as one-fourth the 

distance between superlattice side bands. These were resonant at the Ir Lrrr edge. 

While these satellites appear to be of nlagnetic origin. they indicate that the Co 

layers were arranged in a coherent manner, but with a 90 degree rotation between 

successive blocks. This coldtl he accomplishecl by means of tlorniriant biquaclratic 

coupling. but it is suprising that such coupling could give rise to coherent order. 

Becansc of the intensity of the beam, the sample ~vas found to degrade tluring the 

course of the expcrimcnt, presumably clue to the absorption within the Ir ~ultlerlayer 

when operating close to the Ir L~rr edge. i5'hile data analysis is still underway, we 

have SIICCC~~C~ in growing new sarnples that show ~rnambiquous aritiferrorrlagrletic 

ortler. Thcsc will bc 11sct1 in future runs, and some defocl~ssing of the beam will he 

reqrriretl to givc thc nccwsary intensity while not tlcgratlating the samples.

I Structural Studies of Gene 5 Protein-ss DNA Complexes 

T. C. Terwilliger, R. G. Nanni (LANL) 

X25, 

VOU 

Single-stranded nucleic acid-binding proteins play roles in key cellular processes 

such as DNA replication, recombination, repair, and control of RNA translation. 

This project has focussed on determining the crystal structures of complexes be- 

tween gene V protein and oligonucleotides of lengths from 4 to 16 nucleotides. We 

have obtained crystals of a number of these complexes and have collected x-ray 

diffraction data on those that diffract to high resolution. At this point we have col- 

lected x-ray diffraction datasets to a resolution of at least 3.5 A for the 6 different 

gene V protein-oligonucleotide complexes. 

We have used the structure of the wild-type gene V protein that we determined 

previously to solve the structure of the protein portion of one complex crystal con- 

taining a 16-mer oligonucleotide. This complex crystallized in space group R3 and 

the asymmetric unit of the crystal contains 4 monomers of the protein. The stan- 

dard R-factor for this structure after rigid-body refinement of the protein portion 

alone is 0.39, indicating that the solution we have obtained is likely to be correct. 

We are now in the process of using difference Fourier methods and atomic refinement 

to determine the location of the bound ssDNA in these crystals. 

I Structure Determination of Leukotriene A4 Hydrolase I X25 I 

M.M.G.M. Thunnissen, P. Nordlund (Stocklholm U., Sweden.), and J. Z. Haeg- 

gstrom (Karolinska Institute, Sweden) 

Leukotrienes are lipid mediators involved in inflammatory and allergic processes. 

Leukotriene (LT)B4 is a potent chemotactic stimulus for leukocytes and is regarded 

as an important mediator of inflammation (Samuellson et al, 1987). This com- 

pounds is formed from arachidonic acid via the sequential action of two enzymes. 

5-lipoxygenase catalyzes the formation of the epoxide intermediate LTA4 which is 

in turn converted into LTB4 by the enzyme LTA4 hydrolase. In addition to its 

epoxide hydrolase activity, LTA4 hydrolase also has peptidaselamidase activity to- 

wards synthetic substrates.The amino acid sequence for LTA4 hydrolase shows a 

consensus sequence which is conserved amongs zinc- metalloproteases (Haeggstrom 

et al. 1990). Site directed mutagenesis studies have shown that His295, His299 and 

Glu318 are the three Zn binding ligands and that Glu296 is the catalytic amino-acid 

for the peptidase activity, for which a general base mechanism is proposed (Medina 

et al., 1991). Tyr383 was identified as the potential proton-donor in this mechanism 

(Blomster et al., 1995). However much less is known about the epoxide hydrolase 

activity although mutations at positions 296 and 383 showed that the active sites 

are not identical but rather overlapping. In view of the potential importance of 

LTA4 hydrolase as a target for the treatment of inflammatory diseases, novel se- 

lective inhibitors have been developed (Yuan, 1993) based on substrate mediated 

inactivation of the enzyme. The efficiency of these inhibitors has been tested on the 

epoxide activity of the protein. These new inhibitors are the most potent inhibitors 

of the enzyme presently available, with IC50 between 2 and 0.2mM. With the help 

of structural information, these compounds might be used as lead compunds and 

ultimately be developed into novel anti-inflammatory drugs. 

We recently collected MAD data on the L(II1) edge of Yb at beamline X25. Three 

datasets (peak, ,point of inflection and hard remote) were collected. The data has 

been processed in a preliminary manner using DENZO. The completeness of these 

datasets is around 90% to 3.5A with R merges of 10%. Since data was collected very 

recently no further analysis has been done. Some preliminary Patterson functions 

show interpretable peaks. We hope that we can use these data for initial phasing 

and that subsequent two-fold averaging will be sufficient for tracing the peptide 

chain. 

Blomster, M., Wetterholm, A., Mueller, M.J. Haegstrom, J.Z. (1995) Eur. J. 

Biochem. 231, 528-534. 

Haeggstrom, J.Z., Wetterholm, A., Shapiro, R., Vallee, B.L. Samuelsson, B. 

(1990) Biochem Biophys. Res. Comm. 172, 965-970. 

Medina, J.F., Wetterholm, A., Radmark, O., Shapiro, R., Haeggstrom, J.Z., 

Vallee, B.L. Samuelsson, B. (1991) Proc. Natl. Acad. Sci. USA 88, 7620-7624. 

Samuelsson, B., Dahlen, S.-E., Lindgren, J.A., Rouzer, C.A. and Serhan, C.N. 

(1987) Science 237, 1171-1176. 

Yuan, W., Munoz, B., Wong, C.H., Haeggstrom, J.Z., Wetterholm, A. Samuels- 

son B. (1993) J. Med. Chem. 36, 211-220.

N I X-ray Studies of the Surface Wetting Transition in Liquid Ga-Bi* 

I I X25 I I 

h) 

A H. Tostmann, P. S. Pershan (Harvard U.), E. Dihlasi. B. RI. Ocko (BNL), and hI. 

Deutsch (Bar-Ilan, Israel) 

In contrast to a simple eutectic alloy, such as Ga-In which exhibits Gibbs surface 

segregation, Ga-Bi has a pronounced miscibility gap. This is a prerequisite for the 

occurrence of a surface wetting transition. In the case of Ga-Bi, a macroscopically 

thick Bi rich film completely wets the lighter Ga rich bulk phase if the temperature 

is raised above the characteristic wetting temperature T,. Optical ellipsometry 

studies show that T,, coincides with the rnonotectic temperature of 2203C. 

Using high energy synchrotron radiation, it is possible to monitor the wetting 

transition from a microscopically thin Bi monolayer to a macroscopically thick Bi 

film with atomic resolution. An indication for this phase transition can be seen 

in fig.1. The x-ray reflectivity R from liquicl Ga-Bi is shown for three different 

temperatures, two below and one above T,,. The two reflectivities at 35OC and 

95°C can be fitted by a nnlotlel that assumes a single Bi monolayer on top of the 

Ga rich bulk (solid line). The principal differences between the 35°C and the 95°C 

data can be explained by a Debye-ihller type factor associated with the surface 

roughness due to thermal capillary waves. It is important to note that the basic 

structural feature -- a Bi rich rnonolayer on top of a Ga rich bulk - is not changed 

between 35°C and 95°C. 

In contrast to this. the difference between the 260°C and the 35OC tlata in the 

small wavevector range carmot be explairletl by thermal roughness and a simple 

rnonolayrr model does not fit the 260°C tlata. This indicates a significant change in 

the surface structure for T > T,,,. As can be seen in fig.2, at snlnll q the reHectivity 

for T > T,,. (closed triangles) approaches the Fresnrl reflectivity cxpcctetl from a 

macroscopically thick layer of Bi (dotted line) whereas t h rrflcctivity ~ for T < T,,, 

clearly approaches the Fresrwl reflectivity of Ga. 

'This work is supported by thr DOE grant DE-FG02-88Er45379 

0 01 02 03 04 05 

Figure 1. Measured x-ray reflectivity for s: [I-'] 

liquid Ga-Bi at three different tempera- 

tures normalized to the Fresnel reflectiv- Figure 2. Small angle x-ray reflectivity 

ity of an abruptly terminated ideal sur- for liquid Ga-Bi below(3.7 "C) and above 

face. Solid line: fit (see text). (260 'C) the wetting temperature. 

I Surface Structure of Liquid Indium* I X25 I 

H. Tostmann? P. S. Pershan, 0 . G. Shpyrko (Harvard U.)? E. DiRIasi. B. hI. Ocko 

(BNL)? hI. Deutsch (Bar-Ilan, Israel) 

The surface-normal density profile of liquid metals (LhI) is more complex than 

the relatively simple monotonic decay of density found in dielectic liquids. In the 

case of LhI, the combination of the two-fluid nature, the strong Coulmob interactions 

ancl quantum effects give rise to atomic layering normal to the free surface. 

This has long been predicted by theory and verified recently by our experiments on 

liquid Hg and Ga. Several features of these density profiles are not explained by 

theory. To gain deeper insight into the surface strucutre of LhI, investigations of 

additional Lhl are necessary. RIeasurements on liquicl In are of particular interest 

since In is more free-electron-like than either Ga or Hg. 

The x-ray reflectivity from a liquid In surface is shown in Fig.1. The layering peak 

at 2.2k' is due to interference from the ordered surface layers having a spacing of 

about 2.7A. The data can be fitted by a model representing the layer densities b" 

a sequence of Gaussians decaying in amplit~~de (solid line). The intrinsic density 

profiles of Ga and In can be compared when the effects of the finite temperature 

are removed. In this case, the anlplitude of the first layer is slightly larger for In 

than for Ga and the In la,vering decays faster into the bulk then the Ga layering. 

In addition we recorded the off-specdar tliffi~sc scattering (Fig.2). The solitl linrs 

correspond to the theoretically expected scattering intensity taking into account 

the surface structi~re factor. the experimental resolution and the scattering from 

thermally activated capillary waves. Thr agreement justifies our proceetlurc for the 

separation of capillary intll~cetl roughness from the intrinsic sl~rfacc structure. 

'This work is s~~pportetl by the DOE grant DE-FG02-88Er45379. 

Figure 1. ~Ieasnrecl x-ray reflectivity 

for liquid In at 170°C normalized to the 

Fresnel reflectivity of an abruptly termi- 

nated ideal surface. Solid line: fit (see 

text). 

a - 8 [deg] 

Figure 2. Off-specular diffuse scattering 

from liquid Indium. For clarity. the data 

at 3 and 3..53 are multiplied by 4 ancl 2 

respectively (a: incoming angle. 3: de- 

tector angle).

Non-Brownian Dynamics of Concentrated Colloidal Suspension 

Probed by X-ray Intensity Fluctuation (XIFS) I x25 I 

0. K. C. Tsui and S. G. J. Mochrie (MIT) 

We have performed XIFS measurements of the equilibrium dynamics of suspen- 

sions of charge-stabilized Sbz05 spheres of radius 250 f 40A-I in glycerol. Two 

samples were studied: a dilute sample (sample I) and a concentrated sample (sam- 

ple 11), the latter with an effective hard sphere volume fraction 0.18. Fig. 1 shows 

the temoral autocorrelation for both samples at different wavevectors. For sample 

I, the data fit very well to a single exponential (Fig. l(a)). For sample 11, how- 

ever, this model does not work as well (solid lines in Fig. l(b)). Therefore, we 

have adopted a cumulant form up to the third order in order to fit the data. Ev- 

idently, it provides a much better description (dashed lines in Fig. l(b)). In Fig. 

2, we have plotted Do/D vs. Q, where D = 1/rQQ2 (TQ is the characteristic decay 

time of the autocorrelation) and Do is the Stokes-Einstein diffusion coefficient. For 

sample I, Do/D is nearly constant versus Q, as expected for a dilute suspension 

undergoing Brownian motion. The fact that D is a factor of 2.6 bigger than Do 

is probably due to the presence of water impurity in the sample. On the other 

hand, for sample 11, Do/D increases rapidly with Q, and tends to peak at where 

S(Q) peaks (Q,,, 0.008k1). Physically, the particle density wave at Q, has 

the optimum interparticle separation, therefore any attempt to move the particle 

away from this preferred configuration is suppressed. What is the most interesting, 

however, is that at small Q the asymptotic value of Do/D is bigger than one. Light 

scattering results of suspensions with hard sphere or screened Coulomb interactions 

suggest the opposite. More work is needed to understand the discrepancy. 

TIME (s) 

Figure 1. (a) Autocorrelations vs. time 

for sample I at -31.5OC. (b) Autocorrelations 

vs. time for sample I1 at 

-26.8"C. Solid lines are fits to a single 

4d exponential. Dashed lines are fits to a 

t\3 

t~ cumulant form. 

m 

o SAMPLE 11 O.'5 

0.50 

0 0.003 0.006 0 009 0.012 

0 0 0.002 0.004 0.006 0.008 0.010 0.012 

WAVE VECTOR (A-') 

Figure 2. (a) Do/D vs. wavevector for 

sample I (solid circles) and sample I1 

(open circles). The lines are guides-to- 

the-eye. (b) Structure factor, S(Q), of 

sample 11. 

I Statistical Analysis of X-ray Speckle at X25 

0. K. C. Tsui, S. G. J. Mochrie (MIT), and L. E. Berman (BNL) 

1 ~ 2 1 5 

A highly coherent x-ray beam was produced at the NSLS wiggler beamline X25 

using a rectangular slit 8.9 pm (vertical) x4.2pm (horizontal). By illuminating 

an aerogel sample (a disordered medium) with the beam, a static speckle pattern 

was produced (Fig. 1). Statistical analysis was carried out to study the coher- 

ence properties of the beam, which may be described by a number M, which may 

be considered as the number of independent coherent x-ray fields contributing to 

the observed speckle pattern. We calculated the autocorrelation function and the 

intensity probability distribution of the speckle pattern at various wavevectors, Q 

(0.003 < Q < 0.0lA-l) and obtained the Q dependence of M (Fig. 2(a)) and the 

FWHM of the speckle pattern (Fig. 2(b)). We adopted a model recently developed 

by Albernathy et. al. and found good agreement with the data. Our result showed 

that the number of coherence areas propagated through the slit, Mo, was 2.3 which 

is 35% bigger than what one will expect from transverse coherence length consid- 

erations. We do not understand the discrepancy although beryllium windows and 

beamline optics are possible candidates to explain the difference. 

0 100 200 300 400 500 

Figure 1. Speckle pattern produced by 

an aerogel sample. The axes are la- 

belled by the pixel numbers (1 pixel cor- 

responds to 3 x 10-~A-l). 

"0 0.006 0.012 0.018 

WAVEVECTOR (A-') 

Figure 2. (a) M vs. Q obtained indepen- 

dently from the peak height of the auto- 

correlations (open circles) and fits to the 

intensity probability distribution (solid 

triangles). (b) FWHM of the speckle 

pattern as a function of Q. Solid lines 

are best fits of Abernathy et. a1.8 model 

to the experimental data.

tj 

t3 

to 

0 

High Resolution Data Collection and Structure Refinement of Mito- 

chondrial Cytochrome bcl Complex 

X25 

D. Xia, H. Kim, J. Deisenhofer (HHRII & U. of Texas), C. A. Yu, A. Kachurin, L. 

Zhang, and L. YLI (Oklahoma St. U.) 

Cytochrome bcl Complex (ubiquinol-cytochrome c oxidoreductase, bcl) is the 

middle segment of the respiratory chain in almost all aerobic organisms, and an 

essential component in the photosynthetic machinery in purple bacteria. Green 

plants use highly homologous bsf complex as an important of their energy conservation 

apparatus. The bcl complex is an integral membrane protein; it couples 

the electron transfer from ubiquinol to cytochrome c to the proton translocation 

across the membrane to generate a pH difference and a membrane potential for ATP 

syntheseis. hIitochondrial bcl complex from bovine heart consists of 11 different 

snbnnits. two b-type hernes, one c-type heme and an iron-sulfur cluster with a total 

rnolecnlar weight of 250 Kd and in excess of 2200 amino acid residues. 

The mitoclionclrial cytochrome bcl complex from bovine heart mas pnrifietl and 

crystallized. Bcl crystals diffracted X-ray to 3.3 it resolntion and possess syrnrnetry 

of the space gronp of 14122 with cell dimensions n=b=153.7 ;I and c=597.5 ;I. 

Structnre was tleterminetl using AIIRAS rnethotl with seven heavy metal tlerivatives. 

Cnrrent atomic model of the bcl cornplex coritnins eight corrrpletely sequence 

assigned snbnnits inclntling corel, corc2. cytochrorne b, Rieske iron snlfnr protein, 

suhnnits 6. 7, 10 ar~tl 11; three irico~nplete subunits inclntling cytochrome cl, snbunits 

8 and 9; and prosthet,ic groups including two btype hemes, one c-tvpe henre 

and one 2Fe-2s iron-s~rlh~r clnst,er with total nnrriher of amino acids resitlnes near 

2000. 

The diffraction of cryo frozen bcl crystals is rather weak tlne to large nnit cell 

volurne. high crvstal mosaicity antl anisotropic tlistribntion of crystal packing contacts. 

Thr weak diffraction poses a rrrnjor obstacle to the refinement of bcl complex 

structnrc. Large 1x1 crystals diffract X-ray at high flnx beamline such as X25 of 

NSLS to 2.7 rl resolution or better. itT? have collected a complete high resolution 

data set from a single bcl crystal at hearrrline X2.5 to 2.7 rl resolntion, which was 

carried out with rnnltiplc passes of high rcsolntion scan by translating thc crystal 

and one pass of low rcsolntion scan. The data set is 95% complete to 2.7 rl resolntion 

with a merge R factor of 8.(i%. Structnrc refinement of the bcl cornplex is 

cllrrently nntlerway. 

Structure and Action of Chaperonin: Structure Determination of 

GroEL/GroES Complexes 

X25 

Z. Xu. A. Horwich, and P. B. Sigler (Yale U. & Howard Hughes Medical School) 

The E. coli chaperonin GroEL, a 14-subunit (60k Da each) assembly composed 

of two back-to-back 7-fold rotationally symmetric rings, requires a partner assem- 

bly, GroES, to function. GroES is a 7-fold rotationally symmetric ring of 10 kDa 

subunits which, with ATP is used to release bound unfolded substrate polypeptide. 

One GroES 7-mer is thought to form a functional complex with one GroEL 14- 

mer. In order to understand the interplay of GroES (and nucleotide phosphate) in 

GroEL-assisted polypeptide folding. we have nndertaken the structure cletermina- 

tion of GroEL/GroES complex in the presence of stably bound ADP. The crystal 

structure of GroEL/GroES/(ADP); was tleterminetl at 3.0 angstrom resolution. 

The dramatic change in the overall structure of the GroEL/GroES cornplex can be 

attributed to the remarkable en bloc domain movements in the snbnnits of the ring 

to which GroES is bound (the cis ring). The movernents of these clornains more than 

double the volume of the inside cavity, increase the hytlrophilicity of the cavity's 

lining, and snggest a nicchnnism for peptitle release. These movements also canse 

significant changes in tliv nucleotitle bintling pocket which acconnts for the highly 

asyrnrnetrical bintling of ADP to only the seven cis suhnnits and provide plnusiblc 

links between the binding of GroES antl changes in the bintling/hytlrolysis of ATP.

I Refinements to the Two-Beam Diffraction Interference Technique I X25 I 

Y. Yacoby (Hebrew U.), H. Baltes, R. Pindak, L. Pfeiffer, R. Hamm (Bell Labs), 

R. Clarke (U. of Michigan), and L. Berman (NSLS) 

We previously demonstrated that the two-beam diffraction interference technique 

provided a direct measurement of the phase of the x-ray beam diffracted by a 2D 

crystal [I]. The experimental results indicated that accurate quantitative measure- 

ments required two refinements: a calibration of the diffracted intensity relative to 

the incident intensity and a direct measurement of the amplitude and phase of the 

x-ray reflection coefficient for the incident beam. 

As our calibration signal we used the powder diffracted beam from a 0.4 pm 

Au overlayer. We chose this signal rather than a signal proportional to the overall 

beam intensity because, as illustrated in Fig. 1, this signal is proportional to the 

intensity of that part of the 20 pm incident beam which is in close proximity to the 

portion (indicated by dashed lines) participating in the 2D crystal diffraction. The 

measured intensity of the calibration signal as a function of beam position relative 

to the Au layer shows that the beam intensity varies continuously within the beam 

by about 10% confirming the need for calibration. 

The absolute value of the reflection coefficient was measured directly as a function 

of the angle of incidence, a. The results, shown in Fig. 2 (filled circles), are in good 

agreement with calculations (solid curve). The phase of the reflection coefficient was 

measured as follows: a monolayer of Ni was evaporated on the 2D crystal prior to 

evaporating the Pd mirror layer. The intensity of the Ni fluorescence is proportional 

to the intensity of the standing wave produced by the incident and reflected beams. 

The Ni fluorescence signal is plotted in the lower right figure ( Xs ). The results 

suggest that the phase qualitatively follows calculations (solid curve) for an ideal Pd 

reflector. In particular, note the increase in fluorescence intensity near the critical 

angle where the incident and reflected beams are in-phase. Nonetheless, there exist 

significant deviations in the data suggesting that the GaAs-Pd interface is not a 

simple one justifying our efforts to measure the phase directly. 

[I] H. Baltes et al., Phys. Rev. Lett. 79, 1285 (1997). 

gold diffracted 

Incident / 

crystal / ~i 1 I 

1- 

Figure 1. 0.0 0.2 0.4 0.6 0.8 1.0 

a 

Figure 2. 

Structures and Oxidation States of Layers on Platinum Single Crystal 

Surfaces. I x25 I 

H. You, J. Tanzer, Y. Chu, and Z. Nagy (ANL) 

A cyclic voltammetry scan of the Pt(ll1) surface (not shown) have several prominent 

features associated with the changes in chemical condition of the surfaces. We 

will present a set of preliminary data in this report in order to show that the surface 

resonance scattering through platinum L3 edge is sensitive to the oxidation or chemical 

state of the top layer of platinum surface. The precise control of the oxidation 

state of the surface can be accomplished in electrochemical potential control. 

Single crystals of platinum were prepared using the flame annealing followed by 

an iodine protection scheme. In this way, the surface can be prepared atomically 

flat. This method has previously used to prepare the surface and proven to work. 

Now the top surface platinum atoms are oxidized or reduced via electrochemical 

potential control. 

In Figure 1, as a selected set of examples, calculated (left panel) and measured 

(right panel) x-ray intensities are shown as a function of incident x-ray energy 

through the Pt L3 edge for four different conditions. The top panels are for the 

scan from the bulk platinum. This intensity was measured at the critical angle of 

platinum where we expect the x-ray evanescent intensity penetrate into the bulk. 

The rest of the panels are for scans made at the most surface sensitive Q-positions 

at three different electrochemical potentials (three different oxidation states), i.e., 

at 0.8, 0.1, and 1.2 V, respectively. At 0.8 V, the surface is under open-circuit 

potential and very little charge transfer of the top Pt layer is expected. At 0.1 V, 

the surface is expected to be reduced and at 1.2 V the surface is fully oxidized. It 

is cloi~r that thc-x-ray scattering ir~tcrlsity is extrc:mely scl~sitive 1.0 'the oxidation 

stiitc of thr top atornic layer of platinum. indicatil~g the feasibility of tletccting 

monolayer-level chemical changes. 

Figure 1. Right panel: Measured intensity at various conditions through Pt Lg 

edge. Left panel: Calculated intensity for the experimental conditions.

4j 

N 

N 

CO 

Partitioning of Ferric and Ferrous Iron Between Coexisting Mafic 

Silicates from Adirondack LIetamorphic Rocks 

X26A 

P.D. Crowley, R.E. Stamski (Amherst), h4.D. Dyar (West Chester U.), R.J. 

Nevle, J. S. Delaney (Rutgers U.), A.G. Monders, S. Jin Young (Whitman), H.A. 

Guetschow ( Carleton). E.D. Gutmann, (Williams), D.F. Harrington, R. Graham 

(Union), M. B. Chervasia, (College of Wooster), S. R. Sutton and G.Shea-McCarthy 

(U. Chicago) 

Installation of the focussing mirrors on beamline X26a now allows for the rapid 

(< 15 minute) acquisition of Fe XANES spectra. hIicro-XANES spectra were obtained 

of garnet, plagioclase, olivine, clinopyroxene, amphibole, and biotite from 

amphibolite and granulite facies metamorphic rocks from the Adirondacks. Standard 

petrographic thin sections were analyzed using a roughly 50 x 100 micron 

beam. After subtraction of the main edge baseline, spectra were fitted to determine 

the location of the Fe pre-edge relative to a magnetite standard. From the Fe preedge 

position. ~e+~/Fe+" ratios were determined following the procedl~re of Bajt 

et al. (1994). Using the Fc"+ content of coexisting mafic silicates, partition coefficients 

for Fe" were determinrd. The relative partitioning of Fe3+ among mafic 

silicates was significantly smallrr in granulite facics rocks than in lower temperature 

amphibolite facies rocks. 

( Coordination Effect on Fe Pre-edge SmX Spectra of Garnet ( X26A ( 

P.D. Crowley, R.E. Stamski (Amherst), hl. D. Dyar (West Chester U.), R .J. Nevle, 

J. S. Delaney (Rutgers U.), H. R. Morrison, M. B. Chervasia, (College of Wooster), 

Z. M. Brown (SUNY at Buffalo), A.G. Monders (Whitman), D.F Harrington, H.A. 

Guetschow ( Carleton), E.D. Gutmann, (Williams), S. R. Sutton and G. Shea- 

L,IcCarthy (U. Chicago) 

Synchrotron micro-XANES spectra of garnet were collected on beamline X26A, 

during August 1997, after the installation of Eocussing mirrors just upstream of the 

sample. The garnet samples came from 13 rocks collected to cover a wide range of 

Fe"/l?e2+, including end-member almancline and andradite hIossbauer standards. 

Rleasurements were made on thin sections and grain mounts using a roughly 50 x 

100 micron beam. Spectra were fitted to determine the location of the Fe pre-edge 

relative to a magnetite standard antl calibration following the procedure of Bqjt et 

al. (1994). After subtraction of the main edge baseline. all of the spectra appear to 

be composites of two closely overlapped peaks, probablv relating to the cubic and 

octahedral sites in the structure. Fez+ rich garnet has a prominent peak at -1.9 eV 

(8-fold occupancy) and a smaller peak at f0.5 eV (Few in 6-fold coorclination). 

End-member antlratlite is a composite of two peaks at -0.2 eV antl + 1.3 cV. Thus, 

the shape antl location of the pre-edge is a verv sensitive indicator of the Fe"' 

content of garnet. The composite peaks in the Fe prr-edge were not resolvable prior 

to the installation of the focmsing mirrors. 

1 Gore mountaln 

401 garnet 

: Maximum systematically 

30r displaced 0.2 eV below 

- u, - the gausslan centro~d 

C - 

2 E 

0 : 

$ 20r 

.- N 

1 . 7 

r a 1, 

0 r r \ -: 

,--. , I : 1'- : \, / , \: : 

I - 

:. a : .. ': 

-15 -10 -5 -0 5 

Relative Energy (eV) 

Figure 1. Fe pre-edge after baseline subtraction. This is a composite of two over- 

lapping peaks at -1.8 E\- and 1.0 el7.

FerricIFerrous Microanalyses of Geological Glasses by Synchrotron 

MicroXANES (SmX) 

X26A 

J. S. Delaney (Rutgers U.), S. Bajt (LLNL), S. R. Sutton (U. Chicago), and M. D. 

Dyar (West Chester U.) 

Fe(III)/Fe(II) in numerous geological glasses, determined by wet chemical and 

Mossbauer techniques, correlate linearly with variations in the energy of the Fe K- 

absorption pre-edge measured by synchrotron microXANES (SmX) in fluorescence 

mode using a 12x15 micrometer beam at X26A. Fe in glass is in 4- and 5-fold coordi- 

nation, in contrast to the 6-fold Fe of most of the minerals studied. The magnitude 

of the pre-edge energy change, as a function of Fe(III)/Fe(II), is smaller in glass. 

The calibration line used for pure glasses is also different from that of minerals 

because of the different coordination of the Fe. 'Impure' glasses, that contain crys- 

tallites or that were slowly quenched have pre-edge peak energies that fall between 

those of the 'pure' glasses and 'pure' minerals of comparable Fe(III)/Fe(II) ratio. 

Such 'impure' glasses are typical of geological materials. The impure glass data lie 

in a continuum between glassy to crystalline states with the average coordination 

number of Fe probably reflecting the extent of their short vs. long range ordering, 

or their "crystallinity". The average Fe coordination number of micrometer scale 

areas of glass may in fact correlate with the cooling rate of the glass. 

In SmX, neither a 'pure' glass calibration line nor a 'pure' mineral calibration 

line can be used for microanalysis of such "real-world" samples because effects of Fe 

coordination on the measured signal are significant. Fortunately, the coordination 

of Fe in glassy samples can be determined quantitatively with a combination of 

XANES and EXAFS technique. The ability to measure simultaneously the XANES 

and the EXAFS region of a multivalent element, such as Fe, is already in use for 

the quantitative Fe(III)/Fe(II) microanalysis on minerals and is being explored on 

coexisting glassy phases. 

Preliminary experiments using glass with coexisting minerals are being done to 

measure the partitioning of Fe(I1) and Fe(II1) between the phases. These results 

allow determination of natural crystal growth systematics for materials that were 

not previous possible. 

Redox Ratios with Outrageous Resolution: Solving an Old geological 

Problem with the Synchrotron MicroXANES Probe. 

I X26A I 

J. S. Delaney (Rutgers U.), M. D. Dyar (West Chester U.), S. R. Sutton (U. 

Chicago), and S. Bajt (LLNL) 

In situ measurements of the oxidation state of iron in common minerals have been 

made using the synchrotron microXANES (SmX) technique. The results compare 

very well with wet chemical and Mvssbauer spectroscopic analyses of the same sam- 

ples. Areas of 10 x 20 micrometers have been measured successfully and the results 

demonstrate that both compositional zoning of Fe3+/(CFe) within individual grains 

and the effect of oxide inclusions on bulk analyses can be quantified. Such sample 

heterogeneity cannot be detected by conventional bulk analytical techniques. The 

ability to measure FeS+/(CFe) with spatial resolution comparable to that of the 

electron microprobe further enhances the importance of microbeam techniques in 

the earth and planetary sciences. Direct measurements of parameters constrained 

by oxidation-reduction processes are now possible with the same spatial resolution 

as traditional compositional analyses derived from electron beam and optical mi- 

croscopic techniques. The new Kirkpatrick-Baez mirrors on X26A have increased 

the intensity of the x-ray beam usable for Fe-microXANES, permits rapid analysis 

and the acquisition of data with the level of spatial detail common to conventional 

microbeam techniques. Co-ordinated Smx, electron probe and ion probe studies of 

microvolumes are now feasible and are being done

?' 

t3 

w 

3 

The Spectroscopic Characterization of U in an Evaporation Basin 

Sediment, LA-UR-97-3589 

h1.C. Duff (LANL): D.B. Hunter: P.M. Bertsch (SRELIUGA), C. Amrhein (UC- 

Riverside), D.E. hIorris (LANL), G. Shea-RIcCarthy (U. of Chicago) 

Evaporation ponds in the San Joaquin Valley (SJV), CA used for the containment 

of irrigation drainage waters. have elevated levels of U. The ponds support 

algae which upon evaporation. become incorporated in sediments as depositional 

sedimentary layers of organic matter (OhI). The Oh1 facilitates reducing conditions 

in the setliments. However, our studies have shown U in one pond sediment exists 

as primarily the oxidized form, U(V1)-regardless of the presence of oxidizing or 

reducing conditions. Research was concluctecl with two pond sediments to characterize 

U speciation antl the influence of various leaching solutions on the U speciation. 

The research involved spectroscopic techniques such as X-ray Absorption 

Near Edge Structure (XANES, at the X-26A nlicroprobe beamline) for U oxidation 

state determinations and (at LANL) basic roonl antl low tenlperature time-resolved 

luminescence. These analytical techniques were complernentetl by wet chemical U 

extraction methods which involved the use of non-oxidizing carbonate antl sulfuric 

acid solutio~ls and oxitlizi~~g solutions. X-ray absorption spectroscopy (XAS) utilizing 

synchrotron radiation is a non-invasive, in situ method that can be used to 

distinguish U(V1) antl U(IV) oxidation states. The energy of an X-ray absorption 

edge increases with increasing valence resulting frorn thc reduced shielding of the 

core electrons frorn the ru~cleus. This increase in the binding energy of the core 

levels is often mmift.stctl by shifts iu pre-edge and bonntl-state etlgt: features in a 

XANES spcctrlirr~ that can bc correlated to differences in the oxitlation state of a 

cationic ccntcr. For U-X.+\NES stl~tlies with two sediments (Ponds 14 ant1 IG), the 

slirfricc setlirrients (0-5 crn) had 69 to 75 per cent U(V1) whereas at tlcptli. the Pond 

16 sctlirncnts hat1 '16 per cent (5 to 10 crn depth) antl 4i per ccut (10 to 15 crr~). The 

greater rctluctiori of U in the Pond 16 setlirnei~ts may be clue to tliffercnccs in the 

physical antl cl~ernical characteristics of the pond s~lrfare sediments. This research 

is cmrently work in progress. 

0.6 

U(VI) Standard 

Pond 16 (10 to 15 crn) 

0.4- - -. Pond 16 (5 to 10 crn) 

0.2- --- Pond 16 (0 to 5 crn) 

-40 -20 0 20 40 60 

Figure 1. 

X26A 

Factors Influencing U Redox Processes in Saline, Calcareous Sedi- 

ments. LA-UR-97-3590 

X26A 

h'1.C. Duff (LANL), D.B. Hunter (SREL), P.hI. Bertsch (SREL), C. Amrhein 

(UCR), G. Shea-hkCarthy (U. of Chicago) 

To examine the factors affecting U(V1) reduction in saline pond sediments from 

the San Joaquin Valley. CA. Sediments were equilibrated with natural and synthetic 

pond inlet waters containing 10 mg U(V1) L-' and various potential reducing 

agents. The equilibrations were done under oxidizing conditions (treatments with 

the algae Chlorella) and under 02-limiting conditions (acetate. sucrose antl alfalfa 

treatments). After three weeks of equilibration, sediment U was characterized for 

changes in oxidation state (by XANES using the rnicroprobe at X-2GA) and the 

dissolved U concentrations were dctcrminccl by phospholuminescence spectroscopy. 

The reduction of U(V1) to the less soluble oxidation state U(1V). mas not ohserved 

in the Chlorella, acetate antl sugar treatments. For the treatment with alfalfa (a 

N arid energy source). a loss of 95 percent U frorn solution occllrred along with 

the generation of volatile sulfides. Additionally, the U(IV) was determined to be 

the prinlary U oxidation state in the alfalfa treated suggesting U(V1) reduction to 

U(1V) and U(1V) precipitation occlirretl. Under the retlncing contlitions, the retluction 

of solution U(V1) to U(1V) most likely occurs after significant SO: reduction 

has taken place. I-Iowever, after 4 days under oxidizing conditions, up to 40 per cent 

of the U(IV) in the alfalfa treated setlirnents was oxidized to U(V1). Hence. in contrast 

to some microbial st~itlies which have observed that the rctllictive precipitation 

of U(IV) results in a solid which is not easily oxitlizcd. U(V1) rctll~ction followed 

by precipitation in this system results in a chenlirally labile U(I\') solid (such as 

UOy(,.), uraninitc) tlmt is rcatlily oxitlizetl. i\tltlitionalIy, thrsc rcsl~lts suggest that 

U reduction in the ponds is a fiinction of nutrient (N antl possibly P) availability. 

The results of the equ\llbrat!ons of pond bnlet waters wlth Pond 

14 sedlment and -10 rng U L ' Values In parentheses are after 

96 hours of alr ox~dat~on The first 2 rows represent ln-sltu 

values whlch were obtalned from other studles 

H,S % U Lost % Upl) 

Treatment pH Smell from Solution in Sediment 

Oxidized Sed~ment 8 3 a5 

Anoxic Sedlment 8 2 0 73 

Algae. ONlPW 7 2 0 2 83 

Algae. OSIPW 7 5 0 10 77 

Alfalfa. ANIPW 6 8 0 95 4 4 (34) 

Alfalfa. ASIPW 6 5 O 95 4 0 (48) 

Suqar. ANIPW 

sugar. ASIPW 

6 7 

7.3 

0 69 

94 

75 

86 I$ - - Acetate 

Acetate. ANIPW 7.6 0 20 78 

Acetate. ASIPW 7 2 1 84 

0. 0x1~. A Anoxlc. N Natural; S Synthetic: IPW Inlet Pond Water 

No volat~le sulfides oresent bv smell: 

0 - volat~le sulfides prdsent by shell 

0- 

-30 -10 10 

.... Algae 

30 50 70 

Figure 1. Figure 2.

I Redox Speciation of Cr in Contaminated Soils, LA-UR-97-3591 I X26A I 

M.C. Duff (LANL), D.B. Hunter (SREL), P.M. Bertsch (SREL), P. Longmire 

(LANL), S. Kung (LANL), G. Shea-McCarthy (U. of Chicago) 

At the Los Alamos National Laboratory DOE site, several soils are considered to 

be mixed-waste due to elevated concentrations of chromium (Cr, a RCRA metal) 

and radionuclides. At one site, a former research reactor water cooling tower which 

received over 2 tons of Cr(V1) over a 17 year period was the primary source of 

soil Cr contamination. The determination of soil Cr(III/VI) ratios is important to 

the classification of mixed waste because Cr(II1) is appreciably less toxic and less 

mobile than Cr(V1). Soil, plant and groundwater samples were taken and analyzed 

for Cr content and in most cases Cr oxidation state. Potential factors influencing Cr 

redox chemistry such as water chemistry, soil Mn oxidation state and concentration, 

and organic matter (OM) content were also studied. Soils had up to 1000 mg 

Cr kg-'. Wet chemical soil Cr(V1) extractions determined that Cr(II1) was the 

dominant Cr oxidation state. These findings were further corroborated with in situ 

XANES studies with the microprobe at beamline X-26A on individual soil particles 

based on the absence of the pre-edge peak indicative of Cr(V1). Total soil Cr and 

Cr(V1) values were correlated with soil OM content and based on the XANES 

spectra, multiple forms of soil Cr(II1) species appear to be present. Coarse soil OM 

had percentage levels of Cr with the dominant Cr oxidation state being Cr(II1). 

According to SXRF studies, species of live plants taken from the cooling tower area 

have only trace Cr contents relative to the coarse soil OM suggesting the uptake 

of Cr by the coarse soil OM was postmortem. The Mn-XANES spectra suggest 

oxidized Mn(1V) is the dominant form of Mn, being greater than 80 per cent of the 

total soil Mn. However, results from heated acid digestions suggest that only half 

of the total soil Mn is nitric acid extractable-when it was previously thought that 

soil Mn(1V) is readily extracted with strong acid. Soil Mn(1V) may be chemically 

unavailable or in too low a concentration to catalyze significant Cr(II1) oxidation to 

Cr(V1). The inability of Mn(1V) to oxidize Cr(II1) to Cr(V1) may also exist because 

soil Cr is strongly associated with soil OM. Therefore, it is unlikely the Cr(II1) will 

be oxidized to Cr(V1) over the long term. This study provides a strong potential for 

practical cost savings for mixed-waste characterization and management because it 

shows that: 1) the majority of Cr in the soil is the environmentally benign Cr(II1) 

species, 2) the oxidation of Cr(II1) to the mobile and toxic Cr(V1) is unlikely in this 

system if it remains fairly undisturbed, and 3) the Cr(V1) content is low enough to 

make a final recommendation of "no further action" for this site. 

1.4 TA-2 Soil 

- 1045 

Figure 1 

Results from Cr-XANES Studies on Soils 

(Each 3 bars represent low, rnedlum and Hlgh Cr) 

Figure 2. 

I Chemical Analysis of Interplanetary Dust Particles I X26A I 

G. J. Flynn (SUNY at Plattsburgh) and S. R. Sutton (U. of Chicago) 

Interplanetary dust particles (IDPs), which are fragments of asteroids and comets, 

are collected from the Earth's stratosphere by NASA aircraft. The element abundance 

patterns in meteorites have proven useful in inferring their formation temperatures 

and establishing genetic links between different meteorites. Our prior 

analyses of over 100 small IDPs (about 10 to 20 microns in size) indicate that the 

volatile contents ratios separate those IDPs into two groups - one volatile rich and 

the other having a volatile content similar to the CI carbonaceous meteorites. 

The impact collection technique separates the largest IDPs (greater than about 25 

microns in diameter) into two groups based on structural strength: strong particles 

collected intact, and weaker particles which fragment on collection. The latter group 

are called "cluster particles" because they occur as a localized field of debris on the 

collector. 

We have, thus far, determined element/Fe ratios in 21 large IDPs [I] and 24 cluster 

fragments from the NASA stratospheric collectors. Although the compositions 

of individual particles vary widely, the average composition of the large IDPs differs 

significantly from the average of the cluster fragments. The cluster fragments are 

enriched in the volatile elements Cu, Ga, Ge, Se, Zn, S, and Br compared to the large 

IDPs, suggesting the cluster particles may have formed at a lower temperature than 

the large IDPs. Both types of IDPs have similar contents of the refractory elements, 

except that Ca is lower, by an average of a factor of 3, in the large IDPs compared 

to the cluster fragments. Low Ca IDPs generally contain hydrated minerals, while 

the normal-Ca IDPs are generally anhydrous [2]. 

Our results indicate the large IDPs collected intact and the cluster IDPs have 

different chemical compositions, and, thus, may sample different parent bodies of 

different parts of the same parent body. Previously, Nishiizumi et al. [3], in an 

examination of larger interplanetary dust particles (greater than 100 microns in 

diameter) recovered from polar ices, reported a possible correlation between Cacontent 

and AlZG abundance, a measure of space exposure. Their results suggested 

a higher AlZG content, and thus a longer space exposure duration for the normal-Ca 

than for the low-Ca particles they examined. To determine if the large IDPs and the 

cluster IDPs from the stratosphere have different space exposure ages, and possibly 

different sources, we have begun a collaboration with the noble gas mass spectrometry 

group at Washington University. They will measure noble gas abundances, 

using the concentrations of solar wind gases and of cosmic ray spallation-produced 

NeZ1 to determine space exposure ages, on the same IDPs analyzed for chemical 

composition at X26A. 

References: 1) Flynn, G. J. et al., Meteoritics, 32, A42-A43, 1997. 2) Schramm, 

L. S. et al., Meteoritics, 24, 99-112, 1989. 3) Nishiizumi, K. et al., Earth Planet. 

Sci. Lett., 104, 315-324, 1991.

'? 

t.2 

03 

t.2 

Chemical Analysis of Particle Capture Cells Flown on the MIR Space 

X26A 

Station 

G. J. Flynn (SUNY at Plattsburgh), S.R. Sutton (U. of Chicago). T. Bunch (NASA 

Ames ) 

When high-speed dust particles impact into a slab of lowdensity (tens to a a 

few hundred mg/cc) aerogel the particles generally come to a stop in a distance 

of about 100 particle diameters, leaving a cone-shaped track with either an intact 

dust particle or fragments of the particle at the bottom end of the track. If the 

particle is larger than about 1 micron in size, the entry track can be observed in 

an optical microscope. However, chemical analysis of the particle has required the 

removal of the particle from the aerogel, a labor-intensive process. We previously 

demonstrated that the X-Ray ,2VIicroprobe at beamline X26A could be used for insitu 

chemical analysis of particles captured in aerogel [I]. This capability allows 11s to 

perform major ant1 trace element analysis on particles captured in the aerogels flown 

on earth-orbiting spacecraft, antl to distinguish between orbital debris particles 

(typically metal. paint, or solar cell fragments) antl micrometeorites (si~nilar to 

chondritic meteorites) based on their chemical compositions. 

This year, we analyzed an aerogel collector flown on the Russian space station 

IrIIR. This 65 cm' collector had been exposed to space for three weeks, including one 

week tluring Orionid meteor shower in 1995 and two-weeks in early 1996. Basctl 

on average n~icrornetroritc flux measurements, the probability of one impact by 

a particlc greater than 10 microns in diameter tluring a three week exposure is 

only about 0.3, altho~~gh it mas hoped there might be an enhanced flux during the 

Orionitl shower. Only one "event," correspontling to an object about 10 microns 

in size, was identified in this collector by optical scanning [2], ar~l degradation of 

the arrogel surface during the space expos~~re precluded opticid tletection of smaller 

particles. The track measures about 150 microns in length. The X-Ray XIicroprobe 

a~~alvsis showed high Ca, low Fe and low Ni. a cornposit,ion tiistirictly tlifkrrnt from 

chontlritic meteorites and frorn the interplanetary dust collected from the Earth's 

stratosphere. Further, we found a uniform cornposition along the length of the 

track. rather than a chemical "hot spot" corresponding to a particle at the end of 

the track. SIost likely this event is contamination in thr form of a fiber cast into the 

aerogel tluring manufacture. In the upcoming year. the S-Ray hIicroprobe will he 

11set1 to examine a similar collector flown on the space station SIIR for more ttlan 6 

mor~ths. which should have collected a few particles greater than 10 microns in size. 

\Ye also perforrnetl chemical analyses of aerogcls being developed at the Jet 

Propulsion Laboratory for use on NASA's Stardust mission, schectuletl for launching 

in 1999. Startlust will capt~~re tlust particles during a flight through the tail of 

Cornet I17ild-2. using aerogel captr~re cells. The current effort focmes on insuring 

that the conceritration of contnminants in the silica aerogel being developed for the 

Stardust spacecraft are sufficiently low to allow in-situ chmmical characterization of 

the about 1500 cometary dust fra,gnents greater than 15 microns in size expected to 

be returned to Earth by the Stardust spacecraft in the year 2006. In-situ chemical 

characterization ~vill allow efficient curation of the returned comet tlust samples. 

eliminating the necessity for the labor-intensive removal of each particle from the 

aerogel as part of the sample curation process. 

1) Flynn. G. J. et al.. Lunar Planet. Sci. XX\'II. 369-370. 1996. 2) Yishioka. 

K. et al.. Lunar Planet. Sci. XX\-111. 1029-1030. 1997. 

Chemical Analysis and Fe-XANES Measurements on the ALH84001 X26A 

AIars Meteorite I I 

G. J. Flynn (SUNY at Plattsburgh), S. R. Sutton (U. of Chicago), L. P. Keller 

(hIVA Inc.), and J. S. Delaney (Rutgers U.) 

hIcKay et al. [I] have reported that carbonate globules and dark rim material surrounding 

these carbonate globules from the ALH84001 meteorite contain possible 

indicators of ancient biological activity on hlars. However. the formation temperature 

of these carbonates and rims is disputed. hIcKay et al. [I] suggest a low 

temperature of formation consistent with co-existing biological activity, while Harvey 

and hIcSween [2] infer a much higher temperature, inconsistent with biological 

activity. 

We measured the trace element contents and the Fe-XANES spectra of a fragment 

of a carbonate globule antl a fragment of dark rim material from ALH84001 in an 

effort to understand the origin antl fornlation conditions of the carbonate and the 

rim and their relationship to one another. \Ve tleterrnined the element/Fc ratios for 

S, Cl, Ca, Ti, Cr, hln, Ni, Cu, Zn, Ga. Ge. Se. Br. Sr, Y. and Zr at 5 spots on a 

rim sample and 6 spots on the carbonat,e globule sample. Individual 10 micron spot 

analyses of each sample show nearly order-of-magnit~ltle variability of S, CI. Ga. and 

Br to Fe ratios, indicating that the most volatile ele~nerits in both the carbonate 

and the rim are distributed quite inhomogeneous at the 10 micron scale. However. 

the average element/Fe ratios of the rim and the globule are intlistinguisllable. 

within analysis errors. suggesting the rim material co~~ltl be tlerivetl from the globdc 

material by a closed systctn alteration process. 

An important question is the degree to which the carbonate globules antl rims, 

which are found along cracks in ALH84001, have been contaminatctl during their 

residence on the Earth. Langenawr antl Krahenbuhl [3] have tlernonstratetl that a11 

of the Antarct,ic meteorites they exnminetl showed ncx surface enrichments in the 

halogens, attribl~tetl to contarninatior~ while thr ~rleteorit,es resitletl on the Antarctic 

ice. The CI/Br ratio in the carbonate globule and rim sarnples wc measured is about 

10.000. almost two ortlers-of-magnitl~tle higher than that found in Antarctic ice 

[.I]. suggesting these sarnples have not been significantly contanlinatetl by halogens 

while in the Antarctic. This mas indicate that the carbonatcs mtl rims from the 

interior of ALH84001 have experier~cetl littlr contarnination during their residence 

in .Antarctica. 

The Fe-SXNES spectra of the rim and the globule are identical. within errors, and 

consistent with that of Fe bound in carbonate. Although TESI examination of the 

rin~ samples tlcscribetl by SIcKay et al. [I] indicates the rim contains magnetite, 

Fe-sulfide antl 1Ig-carbonate. Fe bound in carbonate tlomirlates the Fc-S;\NES 

spectrum of the rini san~plc analyzed in this work. 

References: 1) 1IcKay. D. S.. et al. Science. 273, 924-927. 1996. 2) Harvey. R. 

and H. P. SIcSween. Satme. 382. 49ff. 1996. 3) Langenauer. 11. and V. Krahenbuhl. 

EPSL. 120. 431-442. 1993. 4) Spencer. et al.. d. Glacialog. 31. 233ff. 1985.

I The Distribution of Zinc in Chondrules of Primitive Meteorites I X26A I 

G. Herzog, C. Schnabel, and J. S. Delaney (Rutgers U.), G. J. Flynn (SUNY at 

Plattsburgh), and S. R. Sutton (U. Chicago) 

We have begun experiments to determine the microdistribution of the moderately 

volatile trace element zinc in chondrules from primitive meteorites. Chondrules are 

a major, millimeter-size structural component of the chondritic meteorites, the most 

abundant class of meteorites. Information on the microdistribution of zinc is important 

to the understanding of the geochemical behavior of zinc in chondrules, 

which is not well known, and for interpreting the published bulk zinc contents of 

chondrules in the context of various scenarios of meteorite formation. We use the 

X-ray Microprobe at beamline X26A to measure the zinc content and an electron 

microprobe to characterize the sample mineralogy and bulk composition. The meteorites 

to be studied include Allende, Murchison, Semarkona, and several other 

primitive chondrites. 

Traditionallv. " the bulk zinc content of individual chondrules has been measured 

> 

by neutron activation analysis. In our preliminary work we have profiled the spatial 

distribution of zinc in chondrules by exploiting the better than 10-ppm sensitivity 

and better than 25-micrometer spatial resolution of the X-ray Microprobe at beamline 

X-26A. We measure the zinc content at points along a line starting in the host 

matrix and traversing the diameter of the chondrule. 

In four Allende chondrules examined thus far, zinc occurs mainly in silicates 

and to only a limited extent in metal and sulfides. Moreover, both zinc and iron 

concentrations show clear positive gradients running from the core to the edge of 

the chondrule. This trend indicates that bulk zinc contents of chondrules, as are 

typically measured using neutron activation techniques, do not provide a complete 

picture of the zinc behavior in these chondrules. The zinc gradient from the core to 

the edge is consistent with diffusion of zinc into the chondrules after formation. At 

present we favor the interpretation that most of the zinc entered these chondrules 

after their solidification as a result of interaction with the surrounding zinc-rich 

matrix. If so, then measured bulk zinc contents of chondrules in Allende represent 

only upper limits on the compositions of the chondrules immediately after their 

formation. It follows that the zinc contents at the chondrule interiors offer the best 

hope of learning the initial chondrule compositions, and constraining the conditions 

under which the chondrules formed. 

Our experimental results require confirmation through further analyses of chondrules 

from Allende and other primitive meteorites. The technique employed is also 

applicable to the moderately volatile elements Cu and Ge, and we plan to extend 

our study of the spatial distribution and abundances of moderately volatile elements 

in chondrules to these elements as well. 

v~investi~ation of Alloy Element Behavior during Localized 1 X26A 1 

I Corrosion 

H.S. Isaacs (BNL- DAS), M. Kaneko (Nippon Steel Corp., Japan) 

Chlorides and other halides undermine passive oxides and result in localized cor- 

rosion of many metals including stainless steels. Once initiated, continued corro- 

sion depends on maintaining the presence of high concentrations of halide corrosion 

products within the localized corroding site. Hence, both the chemistry and mass 

transfer processes in pits are extremely important. The halide concentration in a 

pit is balanced between increases associated with metal dissolution (causing ionic 

migration into the pit), and diffusion out of the pit. In many cases the concentra- 

tion attains saturation and a salt layer forms at the metal surface. In situ x-ray 

microprobe scans across the stainless steel/chloride solution interface in a work- 

ing electrochemical cell has shown that the salt layer formed was of the order of 

a micrometers thick and depleted in chromium giving a distinct Fe/Cr maximum. 

Chloride fluorescence was too weak to penetrate the thin plastic windows and ad- 

ditions of bromide were made to act as a halide marker. Bromide fluorescence 

intensity gave a maximum intensity just below the region where the Fe/Cr maxi- 

mum was observed. These results suggest that the salt layer is composed of two 

layers, an outer chromium depleted ferrous halide layer and an inner layer richer in 

Br, having a cation stoichiometry of the stainless steel.

tj 

t3 

W 

Salt Layers Formation on Stainless Steel During Localized Corrosion 1 X26A I Elemental Analysis of Dredged hkiterial From the Port of New 1 IP I 

H. S. Isaacs (DAS-BNL) and i\4. Kaneko (Nippon Steel Corp., Japan) 

An in situ study of the chemistry that develops in pits during localized of corrosion 

of stainless steel in chloride solutions has been carried out using energy dispersive 

x-ray techniques. An artificial pit was used to maintain a one dimensional diffusion 

geometry by clissolving back the cross section of a strip of Type 316 stainless steel 

foil mounted in epoxy resin. A high intensity 8 mm diameter polychromatic x-ray 

beam at Beamline x26A was scanned across the steel, a salt layer on the steel. and 

t.he concentrated dissolution products within the artificial pit. It was previously 

concluded that the salt layer on the steel was forniecl mainly by iron chloride, 

and the other metallic elements were present in significantly lower concentrations 

relative to the concentration in the steel. In order to obtain more information of the 

behavior of the halide anion. a fraction of the chloride was replaced with bromide. 

The fluorcsence of this heavier elerncnt could be detected whereas the less energetic 

cliaractcrist~ic x-rays from chlorine which were absorbed by the thin plastic window 

of the cell. Figure 1 shows the x-ray intensities of Fe and Br across the interface 

forrricd between the dissolving steel ant1 the concentrated dissolved products in the 

pit solution. Also shown is the ratio of the Fe/Cr intensity. The high vitl~~cs for 

the Br indicate that a salt layer is present over a range of about 0.015 mm. The 

rnaxirn~im in the Fe/Cr ratio indicates that a salt layer n-it11 a different composition 

is fornictl ac!jncent to the solution arid is abo~~t 0.006 m1n. The results contrast with 

earlier conclnsions where the peak in the Fc/Cr ratio was cor~sitlerctl to be the only 

salt layer present. The present results snggest a duplex salt layer having a cat,ion 

concc~itration similar to that of the steel antl a high ferrous halide layer ac!iacent to 

t11c soll~tion. 

0 -0 

52.85 52.86 52.87 52.88 52.88 

Distance (mm ) 

I York/New Jersey Using Synchrotron Radiation-induced X-ray Emis- X26A 

sion (SRIXE) * I 

K. Jones (BNL) and S.-R. Song (Nat'l Taiwan U. Taipei and BNL) 

The Port of NY/NJ is naturally shallow and, as a result, dredging is required 

in order to ensure the economic viability of the Port. Port operations contribute 

some 20,000,000,000 dollars and about 200.000 jobs to the regional economy. Loss 

of shipping volume to other ports could thus have a major irnpact on the regional 

environment and its prosperity. 

The total volnme of tlreclgetl material generated each year is on the orcler of 

2,000,000 to 6,000,000 cubic yards. A major portion of the material is contarniriatetl 

with organic antl inorganic cornpounds which render it unacceptable for 

ocean disposal. Several alternate disposal methods arc now being ntilizetl including 

use of borrow pits, confined disposal facilities, solitlification/stabilizatiorl followed 

by upland disposal. In addition, removal of contaminants using phvsical/chemical 

washing tecliniq~~cs, thermal desorption, and high-tc~nperature thermal destruction 

is of great interest. 

The X26A x-ray microprobe is being used to make measurements on intlivitl~~al 

setlirnent particles in order to understand the tlistribl~tion of the contarninants in 

both the as-tlrctlgctl materials antl in the processed materials. Ir~forrnation on the 

grain-size tlistributions can be employed in assaying the effectiveness of the tlecontamination 

rnctllotls us~tl and in untlerstantliug possible long-term environnlental 

irnpacts rcsultirig fro111 the final dkp~~d site sclcctctl. The x-ray probe is a1)le to 

work with spati;tl rcsoll~tions of' about 10 rnicrorncters and detection limits of about 

10 fg for the elcrricnts of interest. 

\\i. art cllrrentl,v carrying on tleterrriiriatiorls of elemental concentrations as a 

function of particle size in the as-dredged rnatcrials from Newtown Creek and 

Newark Bay. SIcasurctnents are also matle using conventional bnlk chemistry on size 

fractioris obtninetl with wrt sieving. In atltlitiori. we are inv~stigating the changes in 

the tlistrib~~tions following application of physical washing with high pressure water 

jets to remove sl~rfacc organic materials cornt)irierl with ltse of a chelator to extract 

nietals in the b11lk rnatcrials. \Ye find that a substantial number of the particles are 

highly enriched in one or [nore contarninarit r~~etals. \brk is in progress to tletermine 

correlations lwtmcen the metals antl to tleter~r~ine whether the enrichments are 

specific to a particle type and to tlrterrnine whether thcrt is a sl~rfacr enhancement 

to thr distrilx~tions. 

Figure 1. Figure1 1-ariations of x-ray intensity for Fe and Br across the steel/solution 

interface at a potential of 1.8 \*see with a bulk soltion of 0.1 11 LiBr and 0.9 11 * \\brk supported in part by the VS Department of Energy Contract So. DE-;\C02- 

LiCl. The ratio of Fe/Cr intensities are also shown. 76CH00016 and by the US Environmental Protection -4gency Interagency -Agreement 10s. 

Dl\-89941761-01-0 and D\\-89937890-01-0.

P 

h3 

Secondary Ion Mass Spectroscopy and Synchrotron X-ray Fluores- 

cence in the Study Of the Variation in Metal Content with Time in 

Tree Rings * 

X26A 

R. Martin, T. K. Sham (U. Western Ontario, Canada), K. Jones (BNL), and R. 

Protz (U. of Guelph, Canada) 

The study of tree ring patterns, dendrochronology, is a well-established discipline 

which has been used as a measure of climate variation and other environmental 

events. Dendrodated tree rings provide ideal sources for radiocarbon calibration. 

Ring patterns have even been used to study the prehistoric transportation of con- 

struction beams. 

Analysis of the metal content of tree rings (dendroanalysis or dendrochemistry) 

has the potential both for identifying pollution events such as metal contamination 

from mining operations and for providing a long-term chronology of the kinetics of 

metal deposition and uptake. 

Dendroanalysis must be treated with caution since the mechanism of metal depo- 

sition in tree rings is poorly understood. Such questions as the mode and kinetics of 

metal accumulation in trees as well as the possibility of lateral migration of metals 

with wood have yet to be satisfactorily addressed. Contradictory results appear in 

the literature. It seems unlikely that the questions posed regarding the usefulness 

of dendrochemistry will be easily answered. Resolution of the contradictions may 

depend on obtaining answers to questions on whether or not selected elements are 

mobile in the soil, air, or the wood itself, or if mobility is concentration dependent. 

We have begun an initial investigation of the topic by carrying out measurements 

on specimens from the Northern Black Spruce, Picea mariana, growing in peat in 

the Hudson Bay Lowlands. These samples were selected because good data exist on 

the local soil chemistry and the tree rings are very narrow (of the order of 0.16 mm) 

because of harsh growing conditions in the form of a short season and low nutrient 

availability. 

The experimental approach has been to apply microbeam analytical methods 

based on secondary ion mass spectroscopy (SIMS) and synchrotron-radiation in- 

duced x-ray emission (SRIXE) to measure metal distributions as a function of radial 

distance on the wood samples. The two methods have complementary aspects in 

terms of the sample preparation and the volume of material analyzed. 

Results from the two methods show a seasonal pattern for elements such as 

potassium, calcium, iron, and manganese, with maximum uptake generally at the 

beginning of the growing season. The patterns are of a nature that suggests that 

a significant fraction of each of these species is localized with individual growth 

rings and that if they are diffusing at all, it is at a rate that preserves the local 

enhancement for periods of at least a century. 

Energy-Selective Fluorescence Mapping of Zinc in Zebrafish Em- 

bryos * 

K. Peariso, F. Su, J. Kuwada, and J.E. Penner-Hahn (Michigan) 

X26A 

Zinc has long been recognized to be an essential element in embryonic develop- 

ment. Zebrafish (Danio rerio) embryos have been reported to contain large amounts 

of zinc at the time of fertilization, approximately 1 mM [Berg, personal communi- 

cation]. XANES measurements on whole embryos at various stages during early 

development have shown significant changes in the bulk zinc environment. Using 

the NSLS X-ray microprobe at X26A, we have performed energy-selective, two- 

dimensional maps with 45x40 um2 resolution on zebrafish embryos at four separate 

stages spanning the first eight hours after fertilization (1-cell, 128-cell, high, and 

75% epiboly). Analysis of these maps will allow us to determine the spatial and 

temporal changes of different zinc environments that give rise to the changes we 

have observed in the XANES measurements on the whole embryo. Characteriza- 

tion of these changes will aid in our ability to define the role of different types of 

zinc environments in embryogenesis. 

w 

* Research supported in part by the US Department of Energy Contract No. DE-ACOZcl 

76CH00016. * Supported in part by the NIH, GM-38047 (to JEPH)

Determination of Zinc Content of Poliovirus Protein 2C Expressed I X26A / 

- in -- - E. . coli - - . * 

- I 1 

T. Pfister, E. Wimmer (SUNY at Stony Brook), and K. 1V. Jones (BNL) 

The family Picornaviridae includes the genera Enterovirus, Rhinovirus, Aphthovirus, 

Cardiovirus and Hepatovirus. Each genus contains pathogenic species 

causing a bewildering array of disease syndromes in humans and animals. In contrast 

to the diversity of diseases caused by picornaviruses. the molecular mechanisms 

by which these viruses replicate appear to be similar. Poliovirus, which 

belongs to the genus Enterovirus is one of the best studied viruses among the picornaviruses 

antl can be considered as the prototype picornavirus in many aspects. 

The non-enveloped icosahedral capsid of poliovirns contains one molecule of singlestranded 

positive-sense RNA of 7.5 kb. Dnring infection, the RNA is translated 

into one polyprotein which is co- antl posttranslationally processed to give rise of 

more than 20 fnnctional proteins. The structural proteins are the building blocks of 

the progeny virions. The non-structural proteins inclndc three proteinases responsible 

for polyprotein processing. hIost non-strnctural proteins are involved in RNA 

replication. Among them, the RNA-dependent RNA polymerase 3Dpol is the best 

stntlietl protein. Cknetic analysis and the nsc of specific inhibitors have revealed 

that protein 2C is reqnired for RNA replication. The function of 2C in regard to 

RNA replication is not known. Several properties of 2C have been tlernonstratetl: 

RNA binding, ATPasc/GTPase activity, antl membrane association. It has been 

proposed that 2C may belong to the snperfan~ily 111 of RNA helicases. However, 

no hrlicasc activity of 2C has yet heen deruonstratcd. Protein scqncnce comparison 

rc~vxlctl a conserved cysteine-rich region in the COOH terminns of protein 2C 

of entero- antl rhinovirnscs. In poliovirns, the sequence is: 269 CKNCHQPAN- 

FKRCCPLVC 286. The pattern of cystcine (C) resitlues in the cysteine-rich region 

rcwmblcs the pattern of the C2C2 type zinc finger motif. In C2C2 type ;zinc fingers 

fonr C resitl~~es bintl one zinc ion by coordination. Zinc finger motifs have 

Ixcn shown to n~ctliate the bi~~tling of a protein with nucleic acids, proteins, or 

lipids. LIcthylation of poliovirns protein 2C with iotloacetamitle revealed that the 

C rcsidncs are available for rnethylation and thus ncitlrer oxidized nor involved in 

disldfitle bonds in the infected cell. \Ye are using syncln-otron x-ray Huorescence in 

order to find out wl~ether the cysteine-rich region of poliovirns 2C contains zinc. Either 

full length 2C or the cysteine-rich region of 2C are expressed as fnsion proteins 

with glutathione S-transferase (GST) in E. coli. The fnsion proteins are affinity 

pnrifictl using glutathione-charged Sepharose beads (Pharrnacia. Uppsala, Smctlcn). 

Purified proteins are spotted and dried under vacnnrn on AP1 membranes (Process 

Xnalytics. Orem. Utah. USA). The measnrements are done on the X2GX x-ray 

microprobe beam line. Prelinlinary results indicate that the cysteine-rich region 

contains zinc. The same region in which all cystcines have been replaced by scrines. 

contains approximately fonr times less zinc. 1k are cnrrently determining the 

sources of zinc antl other metal ions by measlning relative metal concentrations in 

bacterial culture media and buffer solutions nsetl during protein purification. This 

will allow us to express and purify CST fusion proteins under defined relative metal 

concentrations leading to a more accurate determination of zinc content in GST 

fusion proteins expressed in E. coli. 

* Research supported in part by US Department of Energy Contract So. DE-.\CO?- 

76CH00016. 

Elemental Microanalysis and Elemental Mapping on Biological Tis- 

S11PS * 

R. Rizzo and F. Vittur (U.Trieste, Italy) 

I X26A I 

Alginate gel beads are used to immobilize cells for a number of fermen- tation 

processes. The suitability of the immobilisation technique depends on the microscopical 

gel strength. For alginate the above property depends on the calcium 

distribution. In fact. calcium is the gelling -inducing agent in alginate systems. 

15% investigated gel beads as large as 0.7 mm with a resolution of 20 microns. the 

data obtained showed that calcium is not homogeneously distributed across bead 

sections exhibiting the highest concentration at the bead surface. In addition to 

this, rnicrobeads obtained in different calcium concentration conditions were investigated 

to get information about the influence of the calcium concentration on the 

ion distribntion into gel. The experimental data were compared with theoret- tical 

expectations obtained by means of mathematical models of gel formation. Beads 

obtained in the presence of two different tlivalent cations were also investigated in 

order to stndy the infl~~ence of a secontl cation on the calcium distribution. Preliminary 

investigations on ion content and distribution in Lichens mere per fornletl 

with the aim to cva111atc these organisr~is as biological sensors for en vironmental 

pollution detection. 

SRIXE was also nsed for stntlies on both porcine articular cartilage antl hnman 

antl porcin osteonic bone. As far as articular cartilage is concerned, sulfnr (as snlfate 

ester) is a minor component of the proteoglycans present in cartilage. In a first set 

of experiments sulfnr distribntion WLS studied in samples of habi tnally loaded and 

habitnally nnloarletl art,icl~lar cartilage. In the loatled tissues, snlfnr concentration 

increased regnlarly from the articular surface to the sub- clrontlral hone while in the 

nnloatletl cart,ilages sulfi~r concentration gained its rnaxirrunn in the central part of 

the sample. These data provctl that protcoglycan concentration is not a para~nctcr 

which could infl~~encc the laminar appearance of articular cartilage. In a second set 

of ~xperimcnts, snlfnr tlistrilmtion was stntlietl as a probe of a tle novo synthesis of 

proteoglycans by isolated chontlrocytes implanted in an alginate gel in experimental 

chontlral dcfccts. A nccr-syntt~esis of proteoglycans tlnring the repair of cartilage was 

obser~wl. 

:Is far as bone is concerned. we studied the distribntion of zinc in hl~nlan and 

porcine bones at t,hc level of the Haversian system (osteons), which arc the fnnctional 

elen~entary units of the secondary bones. \Ye observed a relatively high 

concentratio~i of zinc in the central part of the osteon near the bountlary with the 

central canal. These results will be compared with hystological tlctection of zinc 

in the same tissue i order to obtain a correlation between zinc distribntion and 

the distribution of the enzyme -Alkaline Phosphatase, the zinc-containing enzyme 

responsible for the initial mineralization of the tissue. 

B. TIN. C. Skjak-Braek. F. 1Iicali. F. 1-ittur. R. Rizzo. Carbohydr. Res. 297 

(1997) 101-105. 

E. Fragonas. V. 1Ilynarik. \*. .Tellus. F. SIicali. X Piras. R. Toffannin. R. Rizzo. 

F. \.ittnr. Osteoarthritis and Cartilage. In press. 

\\brk Supported by the Italian lfinistero dell'Universita' e della Ricerca Scientifica e 

Tecnologica and the T. of Trieste.

I Reduction Of Soil Mn Oxides During XANES Studies I X26A I 

D.S. Ross, H. C. Hales (U. of Vermont), and G. Shea-McCarthy (U. of Chicago) 

Soil Mn oxide surfaces are important sites for the redox reactions of other metals 

and organics. XANES spectroscopy is a useful tool for understanding soil Mn oxide 

behavior. However, sample preparation may affect results. Drying a soil lowers 

its capacity to oxidize added Cr(II1) and increases extractable Mn(II), strongly 

suggesting drying-induced oxide reduction. To avoid the effects of drying, we wished 

to examine moist soil samples with XANES spectroscopy. Preliminary studies were 

undertaken to investigate the effect of x-ray beam exposure on the Mn oxidation 

state of moist, high-Mn soils. Repeated scans were obtained on one spot using 

normal analytical conditions. For most soils studied, the absorption edge moved 

about 1 eV lower within three to four scans. For example, Figure 1 shows repeated 

scans (35 minutes in length) of a moist, high-Mn soil from Charlotte, Vermont. 

This same soil showed continuous reduction during ten repeated 8-minute scans. It 

is interesting to note that, contrary to expectations, dried samples of high-Mn soils 

were as or more oxidized than their moist counterparts. Research will continue to 

ascertain the exact cause of the reduction and possible methodologies to avoid it. 

Figure 1. Repeated XANES scans on a moist, high-Mn soil ("supersoil"). 

Role of Manganese and Associated Trace Element Chemistry in 

X26A 

Plant Diseases * 

D. G. Schulze, C. A. Guest, I. A. Thompson, A. Scheinost, and D. M. Huber 

(Purdue U.) 

The redox chemistry of soil manganese plays an important role in Mn uptake 

by plants, the movement through soil of trace elements absorbed on or occluded 

in Mn-oxide minerals, and the etiology of some soil-borne plant fungal diseases. 

We are using micro x-ray absorption near-edge structure (XANES) spectroscopy on 

beamline X26A to study Mn redox chemistry in situ, both in bulk soils and in the 

rhizosphere of live plants. Our work this year has focussed on: (1) detecting and 

quantifying ~ n ~ ~ + n , and ~ Mn4+ + in mixed systems, (2) correlating sequential 

chemical extraction of Mn with changes in the Mn K XANES spectra of soils, 

and (3) developing techniques for using micro-XANES spectroscopy to measure Mn 

oxidation state in the rhizosphere of live plants growing in soils. 

XANES spectroscopy of mixtures of MnS04 (~n~+), a Mn-substituted goethite 

(~n~'), and a synthetic Na-birnessite (Mn4') show that the crest of the x-ray absorption 

edge for Mn3+ occurs between the crest for Mn2+ and Mn4+, as expected. 

We are attempting to develop approaches for quantifying Mn2+, Mn3+, and ~ n 

in these mixed systems. 

NH4-acetate, CuS04, hydroquinone, and dithionite-citrate-bicarbonate were used 

to sequentially extract increasingly less soluble fractions of manganese from the 

surface horizon of a soil cropped to wheat. A XANES spectrum of the soil paste 

was obtained after each step. Initial data analysis suggests a sizable presence of 

~ + 

~ n in ~ the sample. + 

Sample cells are being developed to measure XANES spectra in the vicinity of 

live plant roots growing in soils. We are still testing and evaluating various designs. 

* This research is supported by the USDA National Research Initiative, Grant number 

96-35107-3183.

tj 

h3 

w 

03 

Performance of Kirkpatrick-Baez Microfocusing Mirrors on the 

X26A Microprobe 

S.R. Sutton, hI. L. Rivers, P. J. Eng, and G. Shea-hlIcCarthy (U. Chicago) 

X26A 

The microprobe at beamline X26A at NSLS experienced a major upgrade mith 

the installation in May, 1997, of microfocusing Kirkpatrick-Baez mirrors. The 

Kirkpatrick-Baez optics have the advantage of large working distances (50 mm from 

the downstream end of the second mirror), achromatic operation (5 - 60 keV), i.e. 

no refocusing is required as the monochromator energy is scanned, and fixed offset. 

The dual mirror system consists of trapezoidal, float-glass, Au-coated mirrors (100 

mm long) which are dynamically bent to elliptical shapes using a mechanical ben- 

der. The conlpletc assembly has a footprint of about 0.1 sqnarc meters and is easily 

accommodated on the 0.7 x 1.0 m breadboard holding the remainder of the x-ray 

microprobe apparatus (sample stage, optical viewing microscope, x-ray detectors). 

A long trace profiler was used to measure the RhIS surface roughness of the glass 

prior to coating. The horizontal and vertical mirrors used here gave values of 7 and 

9 microraclians, respectively. At X26A (9 m from source), these mirrors operated 

at 5 mrad focused a 400 x 400 micrometer white bending rnagnet beam tlo\vn to 10 

(vertical) x 15 (horizontal) micrometers (FIVHhI) resulting in a gain (flux/sqnare 

micrometer) of about 1000 over a pinhole. This compares mith the source sizc limits 

for this geometry at X26A of 3 (vertical) antl 14 (horizontal) micrometers. Thus, 

nearly ideal performance was achieved with the horizontal mirror whereas the tle- 

magnification of the vertical mirror was sornemtiat less than ultimately achievable. 

Further retluct,ions is beam sizc will be achieved with higher quality mirrors (e.g., 

polished glass or silicon). This new capability particularly enhances the sensitivity 

of the rnicroprobe for microspectroscopy applications. 

Eng, P. J., h1. L. Rivers, B. X. Yang ancl \V. Schildkamp (1995) hlicrofocusing 4- 

keV to 65-keV x rays with bent Kirkpatrick-Baez mirrors. Proceedings SPIE 2516, 

41-51. 

Yang, B. X., hI. L. Rivers, W. Schildkamp, and P. Eng (1995) GeoCARS micro- 

focnsing Kirkpatrick-Baez mirror bender development. Rev. Sci. Instrum., 66, 

2278-2280. 

Correlated Synchrotron XRF, MicroXANES and Electron 

probe Analysis on Individual,

I Selenium XANES Spectra of Algal Slurries I X26A I 

T.K. Tokunaga (LBNL), T. Lundquist, M. Zarate, W. Oswald, B. Green (U. Cali- 

fornia), S.R. Sutton and G. Shea-McCarthy, (U. Chicago), P. Nuessle (U. Georgia) 

Elevated concentrations on selenium in agricultural drainage waters in the west- 

ern San Joaquin Valley of California have been responsible for wildlife deaths and 

deformities in wetlands receiving such contaminated waters. An algal- bacterial 

treatment process has been developed by the Applied Algal Research Group, to 

remove Se from agricultural drainage waters. Knowledge of the speciation of Se 

among its possible oxidation states is important since its mobility and toxicity are 

very dependent on its chemical form. The forms of Se accumulated in the reducing 

algal slurries have not previously been identified by direct methods. In this inves- 

tigation, X-ray absorption near-edge structure (XANES) spectroscopy was used to 

determine oxidation states of selenium in algal slurry samples obtained from labo- 

ratory chemostats. The XANES of model compounds (elemental Se, seleno-cystine, 

Se-methionine, sodium selenite, and sodium selenate) were collected for later com- 

parison with algal slurry samples. The XANES of two algal slurry samples showed 

that Se, which was originally primarily in the +VI oxidation state in drain waters, 

was reduced to organo-Se and elemental Se forms. Linear combination fits with Se- 

cystine (R-Se-Se-R) XANES as the dominant component (best fits with 65the two 

samples), with secondary contributions from Se(O), provided the closest matches 

to the spectra of algal slurries. Air-drying resulted in algal slurry XANES which 

were better fit with increased proportions of elemental Se (35and 50algal slurries 

occurs as a mixture of several organo-Se forms and Se(0). Inclusion of additional 

model compounds in future comparisons will be useful. The best fit compositions 

reported here should only be interpreted as showing that Se(V1) was reduced to a 

mixture comprised primarily of organo-Se forms, with a smaller fraction as Se(0). 

In future studies, we will examine XANES of algal slurries at various stages along 

the drainwater treatment process. 

Selenium Diffusion and Reduction at the Water-sediment Boundary I X26A 

T.K. Tokunaga (LBNL), S.R. Sutton, G. Shea-McCarthy (U. Chicago), S. Bajt 

(LLNL), and P. Nuessle (U. Georgia) 

Mechanistic understanding of trace element cycling between surface waters 

and sediments can require highly spatially-resolved information at water-sediment 

boundaries, especially when reactions are involved. Such fine-scale information 

is not obtainable by conventional sampling and analytical methods. This study 

demonstrates the application of micro- X-ray absorption near edge structure (micro- 

XANES) spectroscopy for obtaining such direct, in-situ, spatially- and temporally- 

resolved information for selenium. The experiments determined the fate of soluble 

Se(V1) ponded over water-saturated sediments under two different conditions, one 

oxidizing and the other reducing. One sediment system was maintained oxidizing 

by the presence of excess nitrate, while the reducing sediment was nitrate-deficient 

and amended with organic matter. Redox conditions were monitored in each system 

via arrays of Pt microelectrodes. Scanning micro-XANES analyses showed Se(V1) 

removal from ponded waters by diffusion into sediments. The oxidizing system ex- 

hibited purely diffusive transport, without Se reduction. The diffusion profiles were 

well-matched by a finite-difference numerical simulation. In the reducing sediment, 

Se(V1) was transformed to insoluble Se(0) without significant formation of the in- 

termediate Se(1V). Zones of accumulation of insoluble Se(0) were heterogeneously 

distributed. These results show that the scale over which volume averaging of chem- 

ical species is performed at sediment-water boundaries must be selected carefully, 

and that the spatial resolution offered by micro-XANES is well-suited for these 

types of investigations. By combining our measurements on these hydrostatic sys- 

tems with seepage rates characteristic of ponded sediments at Kesterson Reservoir 

(California), we obtain model predictions of Se distributions in sediments which are 

consistent with field data from that contaminated wetland.

t.J 

ip 

Electromigration-induced Stress Measured by Real-time X-Ray Mi- 

X26C 

crodiffraction 

G. S. Cargill 111, P.-C. Wang (Columbia U.), I. C. Noyan, C.-K. Hu (IBh4 Research) 

White beam Laue microdiffraction with a Si(Li) detector has been used for strain 

measurements on passivated aluminum conductor lines with 10 microns spatial res- 

olution. Real-time measurements were made of strains developed during electro- 

migration using a symmetrical reflection geometry to take advantage of the (111) 

fiber texture of the aluminum films. On-chip tungsten pads were used as "internal" 

diffraction standards to correct for angular or energy calibration shifts during the 

experiments. By measuring differences in d-spacings mith time at many locations 

along 200 micron long lines, the strains developed during electromigration could 

be measured with greater precision than the absolute d-spacings. The precision of 

the individual d-spacing measurements was limited by uncertainties in diffraction 

angles, since only a few grains diffracted into the cletector aperature at each location 

along the line. An example of the d-spacing changes at different locations along a 

conductor line caused by passing 1.4 x 10' A/cm2 throngh the line at 260°C for 

nine hours is shown in Fig. 1, together with the biaxial stresses in grain bonntlaries 

detluced from the d-spacings. Values of the stress gradients, e.g. the slope of the 

tlashetl line in Fig. 1, were determined for different current densities antl times, antl 

these are shown as data points in Fig. 2. together with resnlts from rnotlel calcu- 

lations which are shown ils lines for three tlifferent values assumed for the effective 

tliffnsion coefficient D, Good agreement is obtained for the intermediate value 

of D, ff. Electromigration-in(111cecl strain measurements are continuing for other 

line Icngths and widths, for other contluctor line metals antl alloys, and for other 

passivations. 

This work was supported by NSF grants DhIR-9530043, DhIR-9625887, and 

DhIR-9708003, and by IBhI Research. 

- 

,+i; , -0.004 - $ 

0 50 100 I50 

-200 

200 

Distance from cathode end [wm] 

Figure 1. Changes in d-spacing resulting 

from electromigration-induced stresses. 

as described in the text. The clashed line 

is a linear fit to the data points to deter- 

mine the stress gradient. 

0 10 0 10 0 4 

Time [hr] 

Figure 2. Stress gradient produced by 

electromigration with different current 

densities and times, as described in the 

text. The dotted. solid. and dashed lines 

are calculations using the different values 

of D(ef f ). 

I X26C Beamline Upgrades for Protien Crystalography 

G. Shea-McCarthy (U. of Chicago) 

The X26C protien crystallography program has been expanded to include new 

PRT members from Cold Spring Harbor Laboratory and the University of Stony 

Brook. In a collaborative effort with BNL Biology, NSLS RD and Univ. of Chicago 

BioCARS, the X26C beamline has undergone numerous upgrades. 

These upgrades were inclusive of the installation of a water cooled Si(ll1) 

monochronmtor, white beam stop, photon shutter and double exit berillium window. 

These improvements involved moving the 1:l focusing mirror further downstream, 

clecoupling the X26C beampipe from the X26A hutch and upgrading lead shielding. 

This hutch now has the ability to accept a wide white beam (40mm wide x 6mm 

high), focused white, direct monochromatic, or focused monochrornatic beam. 

In addition to mechanical upgrades, a LIAR detector system has also been installed. 

Although the BioCARS Fuji scanner is still available for use, the LIAR detector 

has the advantage of using a single image plate which is scanned and erased 

in a compact pre-aligned unit. The computer system for controlling the X26C 

beamline has also been upgraded to accomotlate the MAR. Two Silicon Graphic 

Indigo I1 workstations and one Penti~~m Pro have been installed to support the 

LIAR software, GRACE (motor control program), and IDL. 

Currently a new lift table is also being constrnctetl to support the hlAR. Fnture 

upgrades will include the addition of a Kappa-goniostat antl a better mirror. The 

existing mirror is coated with Platinllm with a high energy cutoff of 11.56 Kev. The 

possibility of recoating the mirror mith Rhotliu~n is being considerctl. The Kappagoniastat 

will permit arbitrary orientation of the sample and two theta incliniltion 

of the detector. The new goniometer orientation will also provide a much longer 

crystal to detector ctistance, up to one meter.

] X-ray Crystallographic Structure of Aminopeptidase from S. griseus I X26C I 

G. Shoham (SUNY at Stony Brook, & Hebrew U., Israel) 

Streptomyces griseus aminopeptidase (SGAP) is one of the many enzymes that 

are present in the extracellular fluid of cultures of this bacterium. It is relatively 

small (30 kDa), monomeric, heat stable, requires two zinc atoms for activity, and 

is activated by calcium. The heat stability of the enzyme affords relatively simple 

isolation from the rest of the enzymes found in Pronase. The enzyme is specific 

for large hydrophobic amino acids. No cleavage occures if the following residue 

is proline. These properties make the enzyme an attractive tool for use in two 

stage assays of other peptidases in diagnistic applications. Low molecular weight, 

heat stable aminopeptidases like SGAP were proposed as tools for biotechnological 

applications in processing recombinant DNA proteins and fusion protein products. 

The X-ray crystal structure of SGAP has been recently determined by a combi- 

nation of diffraction studies from both synchrotron and rotating anode X-ray data. 

The native, double-zinc form of the enzyme has been determined to 1.75A resolu- 

tion, the apo-enzyme (zinc removed) has been detrmined to 2.1A resolution, and the 

mercury replaced enzyme has been determined to 2.OA resolution. Data collected on 

the X26C beamline at BNLINSLS was especially critical recently in the extention 

of the structure of the native enzyme to higher resolution as well as to determine 

the structure of the enzyme with a substrate analoge. This information is unique 

and extremely important for the determination of the, still unknown, mechanism of 

catalysis of SGAP as well as other double zinc enzymes. 

The protein consists of a central beta-sheet made up of 8 parallel and antiparallel 

strands, surrounded by helices on either side. The active site is located at the 

carbonyl ends of two middle stards of the beta-sheet region. The active site contains 

two zinc cations, each with similar similar ligands, at a distance of 3.6A from each 

other. A calcium binding site has been identified, consistent with the observations 

that calcium modulates the activity of the enzyme. The mechanism by which the 

calcium cation affects enzyme activity is not apparent, since it is located about 25A 

from the zinc atoms of the active site. This and other mechanistic issues of SGAP 

are now under study. 

Time-resolved Laue Crystallographic Studies of Isocitrate Dehydro- 

nenase 

X26C 

B. L. Stoddard, J. Bolduc, D. Dyer (FHCRC), W. G. Scott (MRC), M. Brubaker, 

B. Cohen, A. Mesecar, D. Koshland (UC Berkeley), R.M. Sweet (NSLS) 

Obtaining detailed atomic structural information about intermediate states along 

an enzyme reaction pathway is problematic, because the lifetime of these interme- 

diates are generally several orders of magnitude shorter that the time necessary for 

collection of a complete data set. Several promising methods are currently being 

pursued to overcome this limitation. These include the use of cryological temper- 

atures to physically trap specific intermediate states, chemical trapping, and the 

development of Laue diffraction as a method to decrease the time needed to collect 

high resolution data sets from protein crystals. 

In the previous year we demonstrated the possibility of using site-directed muta- 

genesis for crystallographic visualization, by trapping specific reaction intermediates 

formed by isocitrate dehydrogenase in a steady-state complex (Bolduc, et al. (1995) 

Science 268: 1312; Stoddard et al. (1996) Nature Struct. Biol. 3 (7): 590). We now 

report time-resolved visualization of the rate-limited intermediate complex formed 

by the wild-type enzyme. For this experiment, single-turnover events were trig- 

gered throughout the crystal using flash-photolysis of a variety of caged substrate 

and caged cofactor molecules, and data was collected on a millisecond time-scale. 

Clear difference Fourier maps were produced of the enzymic complex when a caged 

triggering molecule was used that binds in the active site prior to photolysis.

!d 

h3 

A 

h3 

X-ray Topogaphy and Reciprocal Space hhpping of Protein Crys- 

X26C 

t als 

I Mosaic Spread and X-ray Topography of Protein Crystals I X26C I 

V. Stojanoff (ESRF, France), D. P. Siddons (NSLS) and J. Hirschler (Aerospatiale, 

V. Stojanoff (ESRF, France), T. Boggon, J. Helliwell (U. blanchester, England), 

and E. Snell (NASA) 

France) 

A variety of protein crystals were studied using triple-axis diffractometry and 

monochromatic beam topography. Both space-grown and earth-grown crystals were 

studied in order to shed light on the potential benefits or otherwise of zero-gravity 

crystal growth. The experimental arrangement consisted of an unfocussed beam 

monochromatized by a silicon (111) monochromator, together with a six-circle go- 

niometer. The instrument was operated as a triple-axis spectrometer using a 2- 

reflection channel-cut analyzer. Diffraction spots to be analyzed were chosen from 

the resolution shell around 3.5 angstroms, so as to minimize any smearing effects 

clue to wavelength dispersion. Using this setup it was possible to seperate the effects 

of mosaic spread and tl-spacing variations. Indexing of the patterns was achieved 

by collecting one rotation frame on an imaging plate and indexing the resulting 

pattern using Denzo. The crystals studied showed a wide range of behaviours, from 

extremely sharp patterns in both directions of reciprocal space, to very ill-defined 

peaks broad in both directions. Topographic images were then collected at several 

points on the omega rocking curve to try and learn something about the nature of 

the defects giving rise to these properties. 

References: 

hlinor, W. (1993). XDisplayF computer program. Purdue Uninersity, USA. 

Otwinowski. Z. (19933). Oscillation data retluction program, Proceedings of the 

CCP4 study weckrntl, edited L. Sawyer, N. Issacs k S. Bailey, pp.56-62. UK: SERC. 

Otwinowski, Z. (1993b). Scalepack prograrrl. Yalr University, USA. 

Turkey Egg White Lysozyme (TEWL) crystals grown under various conditions 

and containing various impurity levels were studied using monochromatic beam 

diffraction. Rocking curves were measured and high-resolution diffraction images 

recorded on film. The diffraction order was identified by recording a single oscilation 

diffraction pattern on a Fuji image plate. The indexing and integration of this 

pattern was done with the HKL package (Otwinowski, Z. 1993a; Otwinowski, Z. 

1993b; Minor, W. 1993). Preliminary results showed that pure TEWL present 

a full width of half maximum (FWHM) rocking curve of the order of tenths of 

miliarcseconds while TEWL with various impurity levels present rocking curves 

with at least a 10 times higher FWHM The topographs taken along the rocking 

curve are in agreement with this result. hIultiple domains can be observed in TEbVL 

crystals with different impurity lavels. It is hoped that this type of study will lead 

to an understanding of the defect structures and mechanisms in n~acromolecular 

crystals, and thereby lead to improved growth techniques and improved crystal 

structures. 

References: 

hlinor, W. (1993). X-DisplayF computer program. Purdue University, USA. 

Otwinowski, Z. (1993a). Oscillation data reduction program, Proceetli~lgs of the 

CCP4 study weekend, edited L. Sawyer, N. Issacs SL S. Bailey, pp.56-62. UK: SERC. 

Otwinowski, Z. (1993h). Scalepack program. Yale University, USA.

( Crystallographic Studies of Biological Macromolecules 1 X26C 1 

R.-M. Xu (Cold Spring Harbor Laboratory) 

We have begun the using the newly installed MAR image plate detector system on 

beamline X26C. Operating in focused monochromatic mode we have been taking 

single crystal crystallography data over the past year. Numerous data sets from 

crystals of proteins, nucleic acids and protein-nucleic acid complexes have been 

collected. These crystallographic projects include structural studies of oligomeric 

proteases, transcriptional regulators, RNA splicing factors, and novel nucleic acid 

structures. Determination of several of these structures is currently on-going, using 

the high resolution and high quality data collected at X26C. 

The x-ray energy for monochromatic x-ray crystallography at X26C is presently 

limited to less than 11.5 kev, due to the platinum coating of the focusing mirror. The 

mirror will have to be re-coated or replaced before the beamline can be seriously used 

for multiple anomalous diffraction experiments, which has become a frequently used 

approach to solve the phase problem in macromolecular crystallography. We hope 

to remedy the the wavelength limitation soon to allow full-fledged macromolecular 

crystallography operation at X26C. 

X-Ray Computed Microtomography of Laser Drilled Holes in Composite 

Panels for Acoustic Attenuation in Aerostructures 

- 

D. Di Marzio, J. Clarke (Northrup Grumman); J. Ablett, B. Dowd, P. Siddons, B. 

Andrews (BNL) 

Sound attenuation is a major concern in both military and commercial aerostruc- 

tures. Arrays of microholes drilled into nacelles and other aircraft components can 

effectively muffle engine noise. The use of advanced composite structural materials 

present a new challenge for this sound reduction technology. In this project, an auto- 

mated laser drilling system is used to produce hole arrays in graphitelbismaleimide 

composite panels. X-ray computed microtomography was used to nondestructively 

characterize the structure of an early trial 3 mil (76 m) diameter laser hole array 

in a 1 mm thick laminate. Figure 1 shows a 7 m thick computed density slice 

taken parallel to the composite panel surface (parallel to fiber lay-up). Light re- 

gions correspond to high density (low void content) and dark regions correspond to 

low density (high void regions). Each laser drilled hole (dark circle) is surrounded 

by a dark oval. The long axis of the ovals correspond with the direction of the 

graphite fibers. The fiber direction can be seen as parallel striations throughout 

the image (image corresponds approximately to a one-fiber layer). Surprisingly, the 

high void region (dark oval) induced by the laser drilling is displaced from the hole 

by approximately 100 m along the oval minor axis. Within the ovals are slightly 

darker regions suggesting minor laser damage, while at the edge of the holes the 

density increases. This indicates that at the edge and in the immediate vicinity 

of the hole the local structural integrity of the composite is maintained. We have 

demonstrated that x-ray computed microtomography is a highly effective tool for 

the nondestructive evaluation of processed graphite composite materials. 

Figure 1. Reconstructed slice showing structural damage around laser-drilled holes: 

dim. of sample: 2 x 2.5 mm

X-Ray Computed Microtomography Studies on the Biodeterioration 

nf Wood * 

B.L. Illman (U. of Wisc. & Forest Products Lab.), B.A. Dowd (BNL), R.Holaday 

(BNL, currently at Spring-8, Japan) 

Fungal degradation of wood structures causes substantial economic loss world- 

wide. The exact mechanism(s of degradation are not clearly understood. X-Ray 

Computed Microtomography 1 CMT) is being used to characterize incipient struc- 

turd changes that occur during the wood degradation process. Microstructures in 

solid wood were clearly delineated in CRlT images with a resolution of 3 microns 

(Figure 1). The CMT images show well-defined spatial and size distribution of wood 

fibers. A quantitative measure of the internal microstructure of wood was obtained 

using the medial axis formalism developed by W.B. Lindquist [I]. Measurements 

were made of the microgeometry of wood structures to determine the pore spaces 

(porosity) and connected walls (connectivity) of wood fibers. Preliminary calcula- 

tions of connectivity curves show that porosity and connectivity of the structures 

in wood can be measured to quantify changes in wood microstructure that occur 

during degradation. 

[l] W.B. Lindquist,et al., J. of Geophys. Res. Sol. Earth, B101, 8297 (1996). 

F i r 1 Reconstructed tomographic 

slices of control(1eft) and fungal de- 

graded (right) wood. 

* Research supported by LSD;\ grant 94- 

371031016. 

Figure 2. Disconnectivity curves for the 

vessel walls of control (solid ) and de- 

graded (dotted line) wood samples. 

Microtomography of a Boreal Forest Insect * I X27A 

B.L. Illman (U. of Wisconsin, Madison, and Forest Products Lab.); B.A. Dowd 

(NSLS), R. Holaday (presently at Spring-8), and B. Andrews (BNL) 

Computed microtomography (CMT) has been used to image one of the most 

damaging insects affecting North American boreal forests. The spruce bark beetle, 

Dendroctonus rufipennis (Kirby) has reached epidemic proportions in forests of 

Alaska. The beetle's ability to exploit the forest resource is augmented by their 

pheromonally mediated cooperative behavior, and their associations with microbial 

symbionts. The insect - microorganism complex is responsible for a disease on 

Alaskan trees that has killed over a million acres of trees. The goal is to use ChIT to 

better understand the internal microstructure of the beetle and the vectoring system 

used by the insect to transport microorganisms into trees. Especially important is 

the nature and location of beetle - symbiont fungi. Tree - bark beetle - fungal 

systems offer an opportunity to evaluate the effects of ecological interactions across 

multiple spatial and temporal scales, across multiple trophic levels, and among 

diverse taxa. Understanding these relationships codd greatly improve our ability 

to evaluate and devise appropriate forest management practices, and anticipate the 

impacts of multiple abiotic, biotic, and anthropocentric stresses. The ChIT images 

provide information about the juxtaposition of circulatory, respiratory, cytoskeleton, 

and density-determined regions in the beetle. 

Figure 1. 2-D reconstructed tomographic slice through the eyes of the beetle. 

* Research supported by USD-X Forest Service.

I Applications of Computed Microtomography * I X27A I 

K. W. Jones, B. Dowd, B. Andrews, A. M. Peskin, and P. Siddons (BNL) 

We have carried out several exploratory investigations of applications of synchrotron 

computed microtomography (CMT). The work has been done at the X27A 

CMT facility. The equipment provides the capability of measuring tomographic volumes 

with 10' to 10' voxels with spatial resolutions down to about 3 micrometers. 

Four applications are described below. 

1. The microstructure of fractures in rocks is important for understanding of fluid 

transport calculations for petroleum recovery or for transport of pollutants. We are 

now working on the characterization of a fracture in a 1.3 cm diameter rock. Initial 

data have been obtained with a resolution of about 10 micrometers. Measurements 

will also be made using a laser or direct mechanical profiler on the surfaces of the 

separated rock in order to verify the tomographic results. 

2. CMT is being used to determine the microgeometry of sediments taken from 

the Port of NY/NJ. The sediments are basically a gel with a solids content of 

about 35sizes less than 3 micrometers. We are making measurements to determine 

the structure of the particles on the grain-size scale. The results will be used to 

construct models for the sediments which can be used as the basis for calculations 

of contaminant transport through the sediments. Experiments to measure fluid 

transport through the sediments will be initiated shortly. 

3. Measurements have been made on glass fragments under study at Pacific 

Northwest National Laboratory for use in radioactive waste disposal. CMT provides 

a non-destructive analytical method for following degradation of the glass surfaces 

resulting to interaction with fluids. Initial results were encouraging and have given 

insights into improved methods for design - of the reaction chamber used in exposing 

theglass to theAliquid. 

4. Measurements of structures in organic materials are of interest in several fields. 

We have carried out one measurement on polymers using a sample of a standard 

diaper. The polymer structures were clearly resolved and show that CMT should be 

useful in studying the structures of fibers in a variety of applications. For example, 

CMT can be combined with x-ray microbeams and secondary-ion mass spectrometry 

(SIMS) to relate wood morphology to uptake of metals into the growing wood. This 

is being carried out in collaboration with a group from the University of Western 

Ontario. 

* Research supported in part by the US Department of Energy Contract No. DE-ACO2- 

W 76CH00016, Office of Energy Research, Advanced Computational Technology Initiative 

and Office of Basic Energy Sciences Division of Engineering and Geosciences and the US 

UI Environmental Protection Agency under Interagency Agreement No. DW89937890-01-0. 

Characterization of Ultra-Light Weight Materials, Porous Metals, 

Using X-Ray Computed Microtomography 

R. Schulte, R. Meilunas, A. Tobin, J. Papazian, T. Donnellan (Northrop Grum- 

man), B.A. Dowd, D.P. Siddons, and B. Andrews (BNL) 

Recent developments in porous materials have demonstrated the potential to 

achieve ultra-light weight metal structures at reduced cost using a solid-gas eu- 

tectic solidification process known as the Gasar process. The process is capable of 

producing controlled porosity in metals by influencing the size and shape of pores as 

well as the pore distribution. X-ray computed microtomography provides a means 

to assess the nature of the porosity of samples produced using the Gasar process. 

Quantitative evaluation of pore distribution, pore size and shape in these materials 

is important since they are key determinants of the mechanical properties. 

Several samples were inspected with X-ray microtomography on the X27A beam- 

line. The figure shows a 3-D volume section of an aluminum alloy sample rendered 

from the X-ray microtomography data. Information about the porosity such as 

pore shape, size, and distribution are obtained from the tomographic data and will 

be used to develop improved processing methods and models for the production of 

porous metals. 

Figure 1. 3-D Rendering of porous aluminum: 1x1~3 mm.

C3 

@ 

C, 

Measurements of Morphology and Physical Properties of Bubble in 

Vesiculated Basaltic Rocks using X-Ray Computed Microtomogra- 

P ~ Y 

X27A 

S .R. Song (National Taiwan U., Taiwan), W. B. Lindquist (SUNY at Stony Brook), 

B. A. D od, D. P. Siddons, B. Andrews, and K. W. Jones (BNL) 

Synchrotron X-ray computed microtomography (CMT) is applied to five pieces 

of basalt with different occurrences in order to determine the microgeometric structures 

and physical properties of vesicle. Two (Bal and Ba3) and one calcite-filling 

(Sr5) vesiculated lavas from South Africa and two reticulite tephras (Ba14 and 

Ba15) from the Lungkuan Volcano Group in northeast China have been examined 

by ChIT on the X27C beam line. The voxel size varies from 10 t,o 20 microns 

depending on the chosen field of view of the tomographic instrument. A filtered 

back-projection algorithm was employed to the tomographic reconstruction, while 

the medial axis arlalysis of the tomographic volume to obtain physical properties 

of the bubble, e.g., vesicularity, size, connectivity, and specific surface area. Twoantl 

three-dimensional images of these rocks clearly show that most of the bubbles 

are spherical shape, except the sample Bal, with size ranging from hundreds A3gm 

to mm. The shapes of bubble in sample Bal are significantly irregular antl have 

larger size variation. Original shape antl mineral-filling history of bubble in Sr5 can 

also be clearly itlentificd frorn the images. hIetlial-axis statistic analysis show that 

the vesicularity of these rocks vary from 45These results indicate that synchrotron 

X-ray ChIT with rnedial-axis statistic analysis is a good nontlestructive technique 

to quickly get the res~~lts of the morphology and physical properties of bubble in 

basaltic rocks. And, it is also a good mettrod to study the properties of original 

bltbbles of which they have been filled with secontlary rnirlerals. 

X-Ray Computed Microtomography Study on Pumice I X27A 

S. R.Song (National Taiwan U., Taiwan), W. B.Lindquist (SUNY at Stony Brook), 

B. A. Dowd, D .P. Siddons, and K. W. Jones (BNL) 

Pumice is highly vesicular silicic to mafic foam, which will commonly float on 

water. It is a common product of explosive volcanic eruptions and an important 

component of many pyroclastic deposits and volcanogenic sediments. However, the 

measurements of physical properties of bubble are still scarce due to the limitation 

of technique. Synchrotron X-ray Computed microtomography can be used to image 

the internal structures and determine non-destructively the physical properties of 

pumice, such as shape, size distribution, deformation of bubble, thickness of bubble 

wall, vesicularity, connectivit~ ancl specific surface area. The shape, size, cleformation, 

thickness and vesicularity of bubbles are of interest. for example. in studying 

the mechanism of vesiculation ancl processes of magma degassing. Connectivity 

and specific surface area are important in understanding the floating, interaction 

with water and sedimentary processes. Seven pumice samples with different occurrence 

from the Changbeishan volcano of northeast China have been obtained 

to test the value of this approach. Initial ChIT images show the well-defined 3D 

bubble shape, size distribution, deformation, connectivity and preferred orientation 

in pumice. A typical volume image is shown in the Figure. Further works using 3D 

rnetlial-axis statistic analysis to quantitatively determine the properties of bubbles, 

such as vesicularity, connectivity, size distribution antl specific surface area. 

Figure 1. 3-D image of vesiculated basaltic lava: 3x3~3 mm. Figure 1. 3-D image of pumice: 3x3~1 mm

-4 

Conformational Defects in the Crystals of Low Molecular Weight 

Two-Arm Poly(ethylene Oxide) Fractions Crystallized from the Melt 

X27C 

E. Chen, G. Xue, B.3. Moon, F. W. Harris, S. Z. D. Cheng (U. of Akron), B. S. 

Hsiao and F. Yeh (SUNY at Stony Brook) 

Three two-arm poly(ethy1ene oxide) (PEO) fractions have been prepared by a 

coupling reaction. These PEO possess the same molecular weight of 2100 for each 

arm and the coupling agents used were para-(1,4-), meta-(1,3-) and orth- (1,2-) ben- 

zene tetracarboxylic acids. The two arms at the center of PEO molecules form thus 

an angle of 180, 120 and 60 degree, respectively. The coupling agents are defects 

at the chain center. They may substantially affect the two-arm PEO overall molec- 

ular conformation (OMC) in the crystal state. Differential scanning calorimetry 

results show that two populations of the crystals exist depending upon the crystal- 

lization conditions. Although WAXD powder patterns indicate that the fractions 

exhibit the same crystal structure disregarding the different coupling agents used, 

small angle SAXS experiments show two different long spacings corresponding to 

the two populations of the crystals. One of the crystal populations possesses an ex- 

tended OMC in these two-arm PEO fractions, and one layer of defects is in between 

two neighboring lamellae. Another population of the crystals is consisted of an 

once-folded OMC. Therefore, two layers of the defects are included in between the 

neighboring lamellae. So the difference of long spacings is caused by the number of 

layers of the defects in these fractions as well as the phenylene group arrangements 

on the lamellar surfaces. The crystal with once-folded OMC represents the ultimate 

stable state compared to the crystal containing the extended OMC. With changing 

the types of linkage of these two-arms from 1,4- to 1,2-positions at the coupling 

agents, the population having the once-folded OMC increases in the samples under 

the same crystallization conditions. 

(a) Ertendcd OMC @) Once-folded OMC 

Figure 1. The Schematic diagram for the 

(a) extended and (b) once-folded OMCs. 

Note the long spacing L(1F) is larger 

than L (E) . 

Figure 2. SAXS for the PEO frac- 

tions Crystallized at 48'2, (a) linear par- 

ent PEO, b) two-arm PEO with orth- 

linkage, ($two-arm PEO with meta- 

linkage, and (d) two-arm PEO with 

para-linkage. 

In-situ Crystallization Studies of Polybutylene Terephthalate (PBT) 

by SAXSIWAXD 

X27C 

Y. Gao, K. C. Sheth, S. Talibuddin, Y. Wang (GE), B. S. Hsiao, F. Yeh, Z. G. 

Wang (SUNY at Stony Brook) 

Simultaneous small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction 

(WAXD were used to study the crystallization process of polybutylene 

terepthalate IPBT) semi-crystalline polymers. Three GE commercial grade PBT 

materials, Valox195, Valox315 and Valox420, were chosen to study the impact of 

molecular weight and glass filler under both isothermal and non-isothermal conditions. 

A dual-cell jump unit was used to effect crystallization at different crystallization 

temperatures (Tc). At high Tcs (~1800C), crystallization occurred isothermally 

whereas non-isothermal conditions similar to those encountered in injection molding 

were obtained at larger supercoolings. Time-resolved SAXS and WAXD data, at 

various degrees of supercooling, revealed respectively the morphological (crystalline 

lamellae) and crystal structure changes as a function of time. 

Fig. 1 shows the long period, the average distance between adjacent lamellae, 

as a function of nominal isothermal temperatures for three PBT materials. These 

temperatures are equivalent to the wall temperatures in injection molding process. 

The general trend is that the long periods decrease as the degree of supercooling 

increases; in other words, thinner crystalline lamellae are formed at lower molding 

temperatures. At the same wall temperature, both Valox 315 and Valox 420, which 

have comparable molecular weights but are unfilled and 3OValox 195. Fig. 2 shows 

the rate of crystallization (as expressed by l/tc where tc corresponds to the time 

at which the invariant, Q, plateaus out) as a function of nominal isothermal Tcs. 

As expected, lower molecular weight Valox 195 crystallized faster than higher MW 

Valox 315. Valox 420 had the highest crystallization rate, suggesting nucleation by 

the glass filler. 

160 

150 

,. 140 

- -.- Valox 315 

- 

- 

4 

130 - 

'5 : 120 - 

LL - 

@ rro - 

2 . 

100 - 

so - 

80 40 ' " 60 ' " 80 " " 100 " " 120 " " 140 ~ 160 

'Wall" temperatures 

180 200 220 

"Wall" temperature 

Figure 1. Figure 2.

?' 

t3 

@ 

CO 

SAXS Studies of Dendrimer Systems 1 X27C 

T. J. Prosa, B. J. Bauer, and E. J. Amis (NIST) 

Two-dimensional small angle X-ray scattering (SAXS) was used to probe the 

intermolecular and intramolecular structure within various dendrimer solutions. 

Poly(amidoamine) (PAhlAM) and poly(propyeneimine) (DAB-dend-(NHz),y) den- 

drimers were examined in both dilute and concentrated solutions confirming re- 

ported results regarding molecular size and shape1. The availibility of increased 

accesible q range ancl incident flux extended both the quality and range of mea- 

sured particle scattering curves, revealing additional scattering structure for the 

smaller dentlrimer molecules. 

The scattering from dilute solutions of dendrimers were used to extract the single 

particle scattering factors (P(q)) from denclrimers of various generations, resulting in 

direct information about the rnolecular size and intramolecnlar composition of these 

highly branched materials. For most of the larger generation materials (generation 

7 for the PAhIARI tlenclrimers), P(q) has an overall shape that very nearly matches 

the theoretical scattering curve for a constant electron density sphere. 

This function has very distinct minima when qR, = \/3/5(2n + l)7r/2 or when 

qR, = 3.650, 6.084, 8.517, 10.951, etc ... These minima are expected to disappear 

quickly when there is sufficient polydispersity in size and/or shape, or whtn the 

overall particle composition departs subst ant idly from that of n hard sphere. In 

order to assess the particle shape of weakly scattering smaller molecl~les (R, < 25 

or generations 5 6), one needs the combination of large accessible q range and high 

X-ray flux which X27C provides. Preliminary results reveal higher order features 

are also present in PAhIAnI tlendrimers of generations 5 and 6 as well as DAB- 

tlentl-(NH2)x generation 5, suggesting that these dentlrimers also take on a hard 

sphere shape. 

T..J. Prosa. B.J. Baucr, E.J. Amis, D.A. Tomalia, and R. Scherrenberg , J. Polym. 

Sci.: Part B: Polym. Phys., 35(17) (1997). 

- 100 

u n, -- l%PAMAMG10 

J 

80 

: , r -- Sob PAMAM G6 

"0 0 0.05 0.1 015 0.2 0.25 

qK'i 

Figure 1. Dendrimer x-ray scattering scaled by q-' for PARIAI\I generations 5. 6. and 

10. Data has been corrected for empty beam. sample cell. and solution scattering. 

Study of Structure and Morphology of PVDF Fibers Under Stress / X27C 1 

Using Synchrotron Radiation 

J. Wu, J. R/I. Schultz (U. Delaware), F. Yeh, and B. Hsiao (SUNY at Stony Brook) 

Poly(viny1idene fluoride) (PVDF) is a widely used piezoelectric material. Four 

crystalline forms of PVDF have been reported. The a form, or form 11, can be 

prepared by crystallization from the quiescent melt under normal conditions. The 

O form, or form I, can be prepared by mechanical deformation of a form. Other 

crystal structures are prepared under special experimental conditions. 

While the film properties of PVDF have been investigated thoroughly, studies 

on its fiber form are less prevalent. hloreover, the small angle scattering patterns 

of PVDF fibers have rarely been recorded and analyzed with its wicle angle pat- 

terns. In this study, simultaneous wicle angle and small angle x-ray scattering on 

PVDF fibers, spun under 4 different speeds, under stepincreased strain, were car- 

ried out. The experiment was performed at Beamline X27c, NSLS. The 2D IAXD 

and SAXS patterns are recorded by FujiT"' HR-V image plates(200x250mm) ancl 

digitized by a FujiTh' BAS 2000 IP image plate scanner. The drawing unit is based 

on an lnstronTa" model 4222. The experiment result will show the effect of strain 

on structural detail. The enclosed figures are from preliminary data analysis show- 

ing the crystal structure and the morphologv of the nndrawn as well as the fully 

extended fiber spun under 61m/min. They show the strain induced orientation and 

possible crystal structure change. 

Figure 1. SXXS and \l:lXD Patterns, Fignre 2. SXXS and IT-lXD Patterns. 

Strain=O Strain=140'%

CO 

Behavior of Microphase Separation in a Poly(urethane-urea) Film 

X27C 

i~nder Deformation 

- 

F. Yeh, B. S. Hsiao, B. Chu (SUNY at Stony Brook), and B. Sauer (DuPont) 

Synchrotron small-angle x-ray scattering (SAXS) technique was used to inves- 

tigate the behavior of a poly(urethane-urea) film containing segmented hard and 

soft segments under deformation. The film was cast in solvent which showed a 

clear microphase separation without preferred molecular orientation. Under low 

level of deformation ( loo% strain), the stress-induced molecular orientation in some fractions of the 

microdomains becomes non-recoverable (within the experimental time frame). As 

a result, after the stretch and relaxation, the recovered microstructure was found to 

contain multiple populations of domains with different molecular orientation. We 

attribute this to the stress-induced chain orientation of the hard segment, which is 

at a new state of dynamic equilibrium. 

Effect of Polymer Diulent on The Lamellar Morphology of 

Poly(oxymethylene) Blends 

F. Yeh, B. S. Hsiao, B. Chu (SUNY at Stony Brook), and B. Sauer (DuPont) 

X27C 

Poly(OxyMethy1ene) (POM) and its miscible blends were studied by syn- 

chrotron time-resolved small-angle x-ray scattering (SAXS). The blends contain 

small amount of either poly(viny1 phenol) (PVP) which is a high glass transition 

(T,) diluent, or a polyphenol resin low T, diluent. POM, containing very flexible 

main chain that could easily fold back and forth, is highly a crystalline polymer. 

Results indicated that the low T, polyphenol resin is primarily excluded from the 

lamellar morphology of POM, while the high T, diluent is trapped in the lamellar 

microstructure. The processes of the diulent inclusion and exclusion in the lamellar 

morphology are determined by the lamellar growth rate of the neat polymer and the 

mutual diffusion rate of the constituting components. Finally, we observed that the 

lamellar thickness can be thickened isothermally in both POM neat polymer and 

blends of low T, diluent. No sign of isothermal lamellar thickening can be observed 

in the blends of high T, diulent. 

0 500 1000 1500 2000 2500 

0x1 oO 

3000 

Figure 1. SAXS images 

of Poly(urethane-urea) film under 75% 

strain (a) and without strain (b). 

Figure 2. SAXS 

images of Poly(urethane-urea) film under 

200% strain (a) and without strain 

(b). 

Time (sec) 

Figure 1. Morphological variables extracted from the SAXS dat of POM at 140°C. 

30x1 0." 

20x1 0-6 

1 ox1 o-6 

0

Beamline U1 A 

NSLS USERS 

J. Eng, Jr., B.E. Bent, B. Friihberger, and J.G. Chen, "Studies of the Adsorption Geometry and Decomposition 

Mechanisms of Benzene on Clean and Carbide-Modified Mo(11O) Surfaces using Vibrational Spectroscopy",J. of 

Phys. Chem., BlOl,4044, (1997). 

D. Fischer, A. Marti and G. Haehner, "Orientation and Order in Microcontact-Printed Self-Assembled Mono- 

layers ofAlkane-thiols on Gold Investigated withNear Edge X-Ray Absorption Fine Structure Spectroscopy",J 

Vac. Sci. Technol., A4,2 173, (1 997). 

B. Friihberger, J. Eng Jr., and J.G. Chen, "Observation ofAnomalous Reactivities ofNilPt(111) Bimetallic 

Surfaces", Catal. Letts., 45,85, (1997). 

R. Kapoor, S.T. Oyama, B. Friihberger, and J.G. Chen, "NEXAFS Characterization and Reactivity Studies of 

Bimetallic Vanadium Molybdenum Oxynitride Hydrotreating Catalysts",J. ofPhys. Chem., B101,1543, (1997). 

C.C. Yu, S. Ramanathan, B. Dhandapani, J.G. Chen, and S.T. Oyama, "Bimetallic Nb-Mo Hydroprocessing 

Catalysts: Synthesis, Characterization and Activity Studies",J. ofPhys. Chem., B101,5 12, (1997). 

Beamline U2A 

A.F. Goncharov, R.J. Hemley, H.K. Mao, and R. Lu, "Synchrotron Infrared Spectroscopy of Orientationally 

Ordered Phase of Hydrogen", Bull. Am. Phys. Soc., 42,9 1, (1 997). 

H. Kagi, T. Inoue, D.J. Weidner, R. Lu, and G.R. Rossman, "Speciation of Hydroxides in Hydrous 

Ringwoodite", EOS Trans. Am Geophys. Union, 78, S3 12, (1997). 

V.V. Stmzhkin, A.F. Goncharov, R.J. Hemley, and H.K. Mao, "Cascading Fermi Resonances and the Soft Mode 

in Dense Ice", Phys. Rev. Lett., 78,4446, (1997). 

Beamline U2B 

L.M. Miller, G.L. Carr, G.P. Williams, and M.R. Chance, "Synchrotron Infrared Microspectroscopy as a Means 

of Studying Chemical Composition at a Cellular Level", Biophysical J., 72, A2 14, (1 997). 

A. Xie, Q. He, E.M. Scheuring, B. Sclavi, and M.R. Chance, "Far-Infrared Spectroscopy of Coherent Modes in 

Proteins", Prog. In Bioph. & MolecularBiology, 65,42, (1996).

Beamline U3A 

B. Harris, A.J. Burck, J.J. Fitch, D.E. Graessle, D.A. Schwartz, R.L. Blake, and E.M. Gullikson, "Dctcrniination 

of Optical Constants for AXAF Mirrors froni 0.05- 1 .0 keV Through Reflectance Measurcmcnts", 

Incidence and Multilayer X-rav Optical System, SPIE, 31 l3,4O, (1 997). 

Beamline U3C 

U. Diebold and N.D. Shinn, "Adsorption and Thermal Stability of Mn/TiO,(110): 2p X-ray Absorption Spec- 

troscopy and Soft X-ray Photoemission", Sw$ Sci., 343,53, (1 995). 

Beamline U4A 

K. Breuer, K.E. Smith, M. Grcenblatt, W. McCarroll, and S.L. Hulbert, "Dominant Role of thc Surface in 

Photoemission from Quasi-One Di~ncnsional Conductors: K,, ,Moo,", J. PIijx Clicin. Solids, 57, 1803, (1 996). 

A. DCchelette-Barbara, J.M. Tonnerrc, M.C. Saint-Lager, F. Bartolomb, J.F. Birar, D. Raoux, H.M. Fischer, M. 

Piecuch, V. Chakarian, C.C. Kao, M. Gailhannou, S. Lefivre and M. Bcssikrc 

"X-ray Anomalous Diffraction and Resonant Magnetic Scattering X-ray Study of Fc,Mn,-, IIr(00 1 ) Multilaycrs", 

J. Magi?. Magn. Matel-., 165,87, (1997). 

H.-S. Tao, U. Diebold, N.D. Shinn, and T.E. Madey, "Decomposition of P(CH,), on Ru(0001): Comparsion 

with PH, and PCl,", Suif Sci., 375, 257, (1997). 

Beamline U4B 

V. Chakarian, Y.U. Idzerda, C.T. Chen, G. Meigs, and C.-C. Kao, "Studies of Magnetic Materials with Circu- 

larly Polarized Soft X-rays", Annlications of Synchrotron Radiation in Industrial. Chemical, and Materials 

Science, Plenum Press, New York, p. 187, (1 996). 

V. Chakarian, Y.U. Idzerda, C.-C. Kao, and C.T. Chen, "Circularly Polarized Soft X-ray Resonant Magnctic 

Scattering Studies of FeCo/Mn/FeCo Multilayers", J. Magii. Mngii. Matci.., 165,52, (1997). 

V. Chakarian, Y. U. Idzerda, K. M. Keniner, J. -H. Park, G. Meigs, and C.T. Chen, "Giant Magnetic Effects in 

the L-edge EXAFS of 3d Transition Metals", J. Appl PIij:c.., 79,6493, (1 996). 

V. Chakarian, Y. U. Idzerda, H.-J. Lin, C. J. Gutierrez, G. A. Prinz, G. Meigs, and C. T. Chen, "Element- 

Specific Vector Magnetometry of Buried Layers", J. Magn. Magii. Muter-., 156,265, ( 1996). 

J. W. Freeland, V. Chakarian, Y.U. Idzcrda, S. Doherty, J. G. Zhu, J.-H. Park, and C.-C. Kao, "Identification 

Layer Switching in Magnetic Multilayers with X-ray Resonant Magnetic Scattering", AppI. Plij:~. Lett., 7112,276, 

(1997). 

M.M. Grush, J. Chcn, T.L. Stemmler, S.J. George, C.Ralston, R.T. Stibrany, A. Gelasco, G. Christou, S.M. 

Gorun, J.E. Penner-Hahn, and S.P. Cramer, "Manganese L-edge X-ray Absorption Spectroscopy of Mangancse 

Catalase from L. ylantaiuin and Mixed Valcncc Manganese Complexes",,J. Ani. Clicin. Soc., 118,65, (1 996). 

Y.U. Idzerda, V. Chakarian, and J.W. Freeland, "Soft X-ray Magnetic Circular Dichroism at NSLS Bcaniline 

U4Bn, Syn. Rad. New, 10,6, (1997).

K.M. Kemner, V. Chakrarian, Y.U. Idzerda, and W.T. Elam, "Deconvolution of 3d Transition Metal L-edge 

EXAFS andMagneticEXAFSV, Rev. Sci. Instrum., 67,3365, (1996). 

M. Merz, N. Nucker, E. Pellegrin, S. Schuppler, M. Keilwein, M. Knupfer, M.S. Golden, J. Fink, C.T. Chen, V. 

Chakarian, Y .U. Idzerda, and A. Erb, "X-ray Absorption Spectroscopy of Detwinned PrxY ,-xBa,Cu307-y Single 

CrystalsV,J. ofLow Temp. Phys., 105,347, (1996). 

M. Merz, N. Nucker, E. Pellegrin, P. Schweiss, S. Schuppler, M. Keilwein, M. Knupfer, M.S. Golden, J. Fink, 

C.T. Chen, V. Chakarian, Y.U. Idzerda, and A. Erb, "X-ray Absorption Spectroscopy ofDetwinned PrxY,- 

xBa,Cu30,y Single Crystals: Electronic Structure and Hole Distribution", Phys. Rev., B55,9160, (1997). 

J.-H. Park, S.-W. Cheong, and C.T. Chen, "Double-Exchange Ferromagnetism in La(Mnl-xC~x)03", Phys. Rev., 

B55, 1 1072, (1997). 

J.-H. Park, L. H. Tjeng, J. W. Allen, P. Metcalf, and C. T. Chen, "Single-Particle Gap above the Venvey 

Transition in Fe30,", Phys. Rev., B55,128 13, (1 997). 

J.-H. Park, C. T. Chen, S.-W. Cheong, W. Bao, G. Meigs, V. Chakarian, and Y. U. Idzerda, "Electron Spectro- 

scopic Studies of Colossal Magnetoresistance Material La,-xCaxMn03", 

J. Appl. Phys., 79,4558, (1 996). 

J.-H. Park, C. T. Chen, S.-W. Cheong, W. Bao, G. Meigs, V. Chakarian, and Y. U. Idzerda, "The Electronic 

Structure and Metal-Insulator Transition of Perovskite Manganese Oxide Giant Magnetoresistance System7',J. 

Appl. Phys., 79,4558, (1997). 

Beamline U41R 

P. Dumas, M. Suhren, Y.J. Chabal, C.J. Hirschmugl, and G.P. Williams, "Adsorption and Reactivity ofNO on 

Cu(111): A Synchrotron Infrared Reflection Absorption Spectroscopic Study", SurJ: Sci., 371,200, (1 997). 

J. Eng, Jr., K. Raghavachari, L.M. Struck, Y .J. Chabal, B.E. Bent, G.W. Flynn, S.B. Christman, E.E. Chaban, 

G.P. Williams, K. Radermacher, and S.Mant1, "A Vibrational Study of Ethanol Adsorption on Si(100)",J. Chem. 

Phys., 106,9889, (1997). 

R. Henn, J. Kircher, and M. Cardona, "C-Polarized Vibrational Modes in La,Cu04 and La,,,7Sro,,3Cu0, Determined 

by Ellipsometry", Physica, C269,99, (1 996). 

R. Henn, J. Kircher; M. Cardona, A. Wittlin, V.H.M. Duijn, and A.A. Menovsky, "Far-infi-ared C-axis Response 

of La,,,7Sro,,3Cu0, Determined by Ellipsometry", Phys. Rev., B53,9353, (1 996). 

R. Henn, A. Wittlin, M. Cardona and S. Uchida, "Dynamics of the C-Polarized Infrared Active Modes in La, 

xSrxCu04,", Phys. Rev., B56,6295, (1997). 

J. Hrbek, S.Y. Li, J.A. Rodriquez, D.G. van Campen, H.H. Huang, and G.-Q. Xu, "Synthesis of Sulfur Films 

from S, Gas: Spectroscopic Evidence for the Formation of Sn Species", Chem. Phys. Letts., 267,65, (1997). 

J. Kircher, R. Henn, M. Cardona, P.L. Richards and G.P. Williams, "Far Infrared Ellipsometry using Synchro- 

tron RadiationV,J. Opt. Soc. Am., B14,705, (1997). 

L.M. Miller, G.L.Carr, G.P. Williams, and M.R. Chance, "Synchrotron Infrared Microspectroscopy as a Means 

of Studying Chemical Composition at a Cellular Level", BiophysicalJ., 72, A2 14, (1 997).

T. Nanba, and G.P. Williams, "Phase Transitions ofCdS Microcrystals Under High Prcssurc",./. P11j:s. Soc. ./lrpcrrt, 

66, 1526, (1997). 

K. Raghavaehari, Y.J. Chabal, and L.M. Struck, "Vibrational Interactions at Surfaces: H,O on Si(100)", Cltcnt. 

Phys. Letts., 252,230, (1 996). 

A.E. Russell, L. Rubasinghani, T.H. Ballingcr, and P.L. Hagans, "Thin Layer Effects in in sitrr Far-Infrared 

Spectroscopy", .I. Electr~ounalytical Cl~cnt., 422, 197, (1 997). 

L.M. Struck, J. Eng, Jr., B.E. Bent, G.W. Flynn, Y.J. Chabal, S.B. Christnian, E.E. Chaban, K. Raghavaehari, 

A.E. White, G.P. Williams, K. Radennacher, and S. Mantl, "Vibrational Study of Silicon Oxidation: H20 on 

Si(lOO)", Surf Sci., 380,444, (1997). 

D.L. Wetzcl, J.A. Reffner, and G.P. Williams, "Synchrotron Powered FT-IR Microspcctroscopy- Single-cell 

Interrogations", Mikr.ochimica Acta, S14,353, (I 997). 

G.P. Williams, "IR Spectroscopy at Surfaceswith Synchrotron Radiation", Slwf Sci., 368, 1, (1 996). 

Beamline U5UA 

P.A. Dowben, D.N. McIlroy, and D. Li, "Surface Magnetism ofthc Lanthanides", Handbook on the Physics and 

Chemistw of Rare Earths, Edited by K.A. Gschneidner and L. Eyring. North Holland Press, 24, 159, (1 997). 

D. Li, J. Pearson, S.D. Bader, D.N. McIlroy, C. Waldfried, and P.A. Dowbcn. "Spin Polarization of the Con- 

duction Bands and Secondary Electrons ofGd(000 I)", J. Appl. Pltja., 79,5838, (1 996). 

D.N. MeIIroy, C. Walfried, D. Li, J. Pcarson, S.D. Bader, D.-J. Huang, P.D. Johnson, R.F. Sabiryanov, S.S. 

Jaswal, and P.A. Dowben, "Oxygen Induced Suppression ofthc Surface Magnctization of Gd(000 1 )", P11j;s. Rev. 

Lett., 76,2802, (1996). 

C. Waldfried, D.N. McIlroy, D. Li, J. Pearson, S.D. Badcr, and P.A. Dowbcn, "Dissociative Nitrogcn Chenii- 

sorption and Bonding on Gd(0000 I)", Szrrf Sci. Letts., 341, L 1072, (1 995). 

Beamline U7B 

B. Zhao, Photoeniission Studies ofFeRh, M.S. Degree in Physic, Florida Atlantic University, (1 997). 

Beamline U8B 

F.R. McFeely, K.Z. Zhang, and M.M. Banaszak Holl, "Chlorocthanc Physisorbed on Hydrogenated Si(l11): A 

Test System for the Evaluation ofcore Level XPS Assignment rules at SiISiO, Intcrfaccs", Mrrt. Rcs. Soc. Sjuup., 

446, 15, (1 997). 

K.Z. Zhang, M.M. Banaszak Holl, J.E. Bender, IV., S. Lee, and F.R. McFecly, "Si 2p Core Level Shifts at the 

Si(lOO)/SiO, Interface: an Experimental Study", P1tj.s. Re\,., B54,7686, (1 996). 

K.Z. Zhang, M.M. Banaszak Holl, and F.R. McFeely, "Soft X-ray Si 2p Core-level Spectra of H,Si,0,2 

Physisorbed on Si(l1 I)-H: Additional Experimental Evidence Regarding the Binding Energy Shift ofthe HSiO, 

Fragment", Mut. Rex Soc. Syntp., 446,241, (1 997).

K.Z. Zhang, J.N. Greeley, M.M. Banaszak Holl, and F.R. McFeely, "The Role ofExtra-Atomic Relaxation in 

Determining Si 2p Binding Energy Shifts at Silicon/Silicon Oxide Interfaces", J. ofAppl. Phys., 82,2298, (1 997). 

K.Z. Zhang, L.M. Meeuwenberg, M.M. Banaszak Holl, and F.R. McFeely, "ANew Model Silicon/Silicon Oxide 

Interface Synthesized from Hl,Sil,O,, and Si(100)-2xlm, Japan J. ofAppl. Phys., 36,1622, (1 997). 

Beamline U9B 

L.A. Kelly, J.G. Trunk, and J.C. Sutherland, "Simultaneous Recording ofthe Spectral, Temporal and Polarization 

Properties of Emission Spectra", Society for Photo-Optical Instrumentation Engineers, 2980,2, (1 997). 

L.A. Kelly, J.G. Trunk, and J.C. Sutherland, "Time ResolvedFluorescence PolarizationMeasurements for Entire 

Emission Spectra with a Resistive-Anode, Single-Photon-Counting Detector: The Fluorescence Ornnilyzer", Rev. 

of Sci. Instrum., 68,2279, (1997). 

E.S. Stevens, "Carbohydrates", Circular Dichroism: Conformational Analysis of Biomolecules, edited by G.D. 

Fasman, Plenum Press, pp. 501-530, (1996). 

D. Wisniewski, W. Drozdowski, A.J. Wojtowicz, A. Lempicki, P. Dorenbos, J.T.M. De Haas, C.W.E. VanEijk, 

and A.J.J. Bos, "Spectroscopy and Thermoluminescence ofLuAlO,:Ce", Acta Physica Polonica, A90,377, (1996). 

A. J. Woj towicz, "New High Performance Scintillators Based on Re-Activated Insulator Materials", Acta Physica 

Polonica, Ago, 215, (1996). 

A.J. Wojtowicz, A. Lempicki, D. Wisniewski, M. Balcerzyk, and C. Brecher, "The Carrier Capture and Recom- 

bination Processes in Ln3+- Activated Scintillators", IEEE Trans. in Nucl. Sci., 43,2 168, (1996). 

Beamline U11 

S.-C. Kuo, Z. Zhang, S.K. Ross, R.B. Klemm, R.D. Johnson, 111, P.S. Monks, P.T. Thorn, Jr., and L.J. Stief, "A 

Discharge Flow-Photoionization Mass Spectrometric Study of HNO: Photoionization Efficiency Spectrum 

andIonization Energy; and Proton Affinity of NO", J. Phys. Chem., 101,4035, (1997). 

R.P. Thorn, Jr., L.J. Stief, S.C. Kuo, and R.B. Klemm, "The Ionization Energy of C1,O and C10, Appearance 

Energy of C10' (C1,O) and Heat of Formation of C1,0", J. Phys. Chem., 100,14178, (1996). 

Beamline Ul3UA 

S. Conrad, D.R. Mullins, Q.-S. Xin, and X.-Y. Zhu, "Thermal and Photochemical Deposition of Sulfur on 

GaAs(100)", Appl. SurJ: Sci., 107,145, (1996). 

D.R. Huntley, D.R. Mullins, and M.P. Wingeier, "Desulfurization of Thiophenic Compounds by Ni(l11): 

Adsorption and Reactions of Thiophene, 3-Methyl Thiophene and 2,5-Dimethyl ThiopheneV,J. Phys. Chem., 

100, 19620, (1996). 

D.R. Mullins, "Enhancement of Methane Formation from Methanethiol Adsorbed on a Strained Ni Film on 

W(OOl)",J. Phys. Chem., lOl,lOl4, (1997). 

D.R. Mullins, D.R. Huntley, T. Tang, D.K. Saldin, and W.T. Tysoe, "The Adsorption Site and Orientation of 

CH3S on Ni(l1 l)", SurJ: Sci., 380,468, (1997).

D.R. Mullins, and P.F. Lyman, "The Interaction of Methanethiol with Sulfur Covcrcd W(OOl)", L(rrlgnluir., 12, 

6382, (1 996). 

D.R. Mullins, T. Tang, X. Chen, V. Shneerson, D.K. Saldin, and W.T. Tysoc, "The Adsorption Site and Oricn- 

tation of Ch,S and Sulfur on Ni(O01) using Angle-Resolved X-ray Photoelectron Spcctroscopy", Stwf Sci., 372, 

193, (1 997). 

S.H. Ovcrbury, and D.R. Mullins, "Geonletric and Electronic Structure of Sulfidcd Ni Films on W(OO1) Studied 

by Low Energy Alkali Ion Scattering and Soft X-ray Photoemission", S11yf Sci., 369,23 1, (1 996). 

A.A. MacDowell, Z. Shcn, K. Fujii, J.E. Bjorkholni, R.R. Freeman, L. Fetter, D.W. Taylor, D.M. Tcnnant, L. 

Eichner, W.K. Waskiewicz, D.L. White, D.L. Windt, and O.R. Wood, 11, "Extrcnic Ultraviolct 1 : 1 Ring-Ficld 

Lithography Machine", OSA Trcnds in Optics and Photonics Vol. 4 Extreme Ultraviolet Lithography, cditcd by 

G.D. Kubiak and D.R. Kania, Optical Society of America, pp. 192- 198, (1 996). 

K.B. Nguyen, A.A. MacDowell, K. Fujii, D.M. Tcnnant, and L.A. Fetter, "At-Wavclcngth Inspection ofEUVL 

Mask Defects with an Offncr 1X Offner Ring-Field System", OSA Trcnds in Optics and Photonics Vol. 4 

Extreme Ultraviolct Litlio~raphv, edited by G.D. Kubiak and D.R. Kania, Optical Society of Anicrica, pp. 49-53, 

(1 996). 

D.A. Tichenor, A.K. Ray-Chaudhuri, G.D. Kubiak, K.B. Nguyen, S.J. Haney, K.W. Bcrgcr, R.P. Nissen, Y .E. 

Perras, P.S. Sin, L.I. Weingarten, P.N. Keifer, R.H. Stulen, R.N. Shagam, W.C. Sweatt, T.G. Smith, O.R. 

Wood, 11, A.A. MacDowell, J.E. Bjorkholni, T.E. Jewell, F. Zernike, B.L. Fix, and H.W. Mauschildt, "P~.ogrcss in 

the Developmcnt of EUV Imaging Systems", OSA Trends in Optics and Photonics Vol. 4, Extrcnic Ultraviolct 

Lithography, edited by G.D. Kubiak and D.R. Kania, Optical Society of Anicrica, pp. 2-8, (1 996). 

Beamline U14A 

R.A. Bartynski, E. Jensen, S.L. Hulbcrt, and C.-C. Kao, "Auger Photoclcctron Coincidence Spcctroscopy 

using Synchrotron Radiation", Prog in Sir$ Sci., 53, 155, (1996). BNL 64645. 

A.K. See, R.A. Bartynski, A. Nangia, A.H. Weiss, S.L. Hulbcrt, X. Wu, and C.-C. Kao, "Enchanced Corc Lcvel 

Photoeniission from Oxide Surface Defects Using Augcr-Photoelectron Coincidcnce Spcctroscopy", S11$ Sci. 

Lett., 383, L735, (1997).

I 

I 

I 

1 

1 

Beamline XI A 

H. Ade, "Compositional and Orientational Characterization of Polymeric Systems with X-ray Microscopy", 

Trends in PolymerScience, 512,58-66, (1997). 

H. Ade, B. Hsiao, G. Mitchell, E. Rightor, A. P. Smith, and R. Cieslinski, "Chemical and Orientational Imaging 

ofPolymeric Samples", edited by G.W. Bailey and A.J. Garratt-Reed, Proceedings ofthe 52 Annual Meeting of 

the Microscopy Society ofAmerica. San Francisco, San Francisco Press, pp. 68-69, (1 994). 

J. M. Boese, X-ray AbsorptionNear edge Structure ofAmino Acids and Pevtides, M.A. Thesis, Department of 

Physics, State University ofNew York at Stony Brook, (1996). 

C.J. Buckley, "The Measuring and Mapping of Calcium in Mineralised Tissues by Absorption Difference Imag- 

ing", Rev. Sci. Instrum., 6612, 13 18-1321, (1995). 

C.J. Buckley, "Imaging of Calcium Deposits in Cartilage by Scanning X-ray Microscopy", Bone, 13,100, (1992). 

C.J. Buckley, S.Y. Ali, C. A. Scotchford, M. Rivers, K. L. D'Amico, J. H. Dunsmuir, and S. R. Ferguson, "Imag- 

ing of Calcium Deposits in Human Cartilage", Scanning, 14,27-28, (1992). 

C.J. Buckley, S. J. Bellamy, N. Khaleque, S. Downes, andX. Zhang, "Possibilities for Chemical State Imaging of 

Calcium Compounds", edited by V. V. Aristov and A. I. Erko, X-ray Microscopy IV, Bo~orodskii Pechatnik. 

Proceedings ofthe 4~ International Conference. Chernogolovka. Russia, pp. 207-2 12, (1994). 

C.J. Buckley, R.E. Burge, G.F. Foster, S.Y. Ali, and C.A. Scotchford, "X-ray Probe Mapping of CalciumDeposits 

in Articular Cartilage", edited by P. B. Kenway, P. J. Duke, G. W. Lorimer, T. Mulvey, I. W. Drummond, G. 

Love, A. G.Michette, and M. Stedman, X-Rav Optics and Microanalysis, Bristol, IOP Publishing, pp. 62 1-626, 

(1992). 

C.J. ~uckley, S. Downes, N. Khaleque, S. J. Bellamy, and X. Zhang, "Mapping the Density and Mineral Phase of 

Calcium in Bone at the Interface with Biomaterials using Scanning X-ray Microscopy", edited by G.W. Bailey 

and A.J. Garratt-Reed, Proceedings ofthe 52 Annual Meeting ofthe Microscopy Society of America. San Francisco, 

SanFrancisco Press, pp. 44-45, (1994). 

H. N. Chapman, "Phase-Retrieval X-ray Microscopy by Wigner-Distribution Deconvolution", Ultramicroscopy, 

66, 153-172, (1996). 

H. N. Chapman, K. A. Nugent, S. W. Wilkins and A. V. Rode, "Capillary X-ray Optics", edited by C. Jacobsen 

and J. Trebes, Soft X-ray Microscovy, SPIE, 1741,40-50, (1992). 

H. Chapman, S. Williams, and C. Jacobsen, "Imaging of 30 nm gold Spheres by Dark-field Scanning Transmis- 

sion X-ray Microscopy", edited by G. W. Bailey and A. J. Garratt-Reed, Proceedings of the 52 Annual Meeting of 

the Microscopy Society of America, San Francisco Press, pp. 52-53, (1994). 

G. D. Cody, R. E. Botto, H. Ade, and S. Wirick, "The Application of Soft X-ray Microscopy to the in situ 

Analysis of Sporinite in Coal", Intern. J. of Coal Geo., 32,69-86, (1996). 

J. R. Gilbert, Soft X-ray Microimaging of Whole Wet Cells, PhD Thesis, California Institute of Technology, 

1 Pasadena, California, (1 992). 

K. K. Goncz, A Comprehensive Study ofthe Phvsical Properties ofkolated Zymogen Granules using Scanning 

Transmission X-ray Microscopy, PhD Thesis, Department ofBiophysics, University of California, (1 994).

K. K. Goncz, R. Behrsing, and S. S. Rothman, "The Morphology and Stnlcture ofZymogcn Granules", Cell trrltl 

Tissue Res., 280,5 19-530, (I 995). 

K. K. Goncz, R. Behrsing, and S. S. Rothman, "A Study ofthe Properties ofzymogen Granules using X-ray 

Microscopy", edited by V.V. Aristov and A. I. Erko, X-ray Microscopy IV, Bororodskii Pechatnik, Procccdin~.~ of 

International Conference. Chernorolovka. Russia. Septenibcr 20-24, pp. 256-264, (1 994). 

K. K. Goncz, M. Moronne, W. Lin, and S. Rothman, "Measuring Changes in thc Mass of Single Subccllular 

Organelles using X-ray Microscopy", edited by C. Jacobsen and J. Trebes, Soft X-ray Microscopy, SPIE, 1741, 

342-350, (1992). 

K. K. Goncz and S. S. Rothman, "Membrane Protein Transport in Eukaryotic Secretion in Cells", MCWIINY~IIC 

Protein Transport, 3,279-293, (1 996). 

W. S. Haddad, I. McNulty, J. E. Trebes, E. H. Anderson, L. Yang, and J. M. Brasc, "Demonstration of Ultra- 

High-Resolution Soft X-ray Tomography using a Scanning Transmission X-ray Microscope", editcd by G. W. 

Bailey and A.J. Garratt-Reed, Proceedings ofthc 52 Annual Mecting ofthe Microscopy Society of America, San 

Francisco Press, pp. 3 12-3 13, (1 994). 

M. R. Howells, C. J. Jacobsen, and S. Lindaas, "X-ray Holographic Microscopy using the Atomic-Force Micro- 

scope", edited by V.V. Aristov and A.I. Erko, X-ray Microscopy IV. Cheniogolovka, Russia, Bogorodskii 

Pechatnik. Proceedings of the 4 ! International Conferencc, September 20-24, pp. 41 3-427, (1 994). 

A. Irtel von Brcnndorff, M. M. Moronne, C. Larabell, P. Selvin, and W. Mcyer-Ilse, "Soft X-ray Stimulated High 

Resolution Luminescence Microscopy", edited by V.V. Aristov and A.I. Erko, X-ray Microscopy IV. Bogorodskii 

Pechatnik. Proceedings ofthe 4 

343, (1 994). 

b I n t e m a t i o n a l t e ~ i i b e20-24, r pp. 337- 

C. Jacobsen, "Soft-X-ray Microscopy: Imaging of Biological Systems", edited by E. Burattini and A. Balcrna, 

Biomedical Applications of Synchrotron Radiation. Volume CXXVIII Corso, Amsterdam, 10s Prcss, pp. 9 1 - 109, 

(1 996). 

C. Jacobsen, H. N. Chapman, J. Fu, A. Kalinovsky, J. Kirz, J. Maser, A. Osanna, S. Spector, D. Tennant, S. 

Wang, S. Wirick, and X. Zhang, "Biological Microscopy and Soft X-ray Optics at Stony Brookw,./. qfElwt. S')cct. 

andRelatedPheno., 80,337-341, (1 996). 

C. Jacobsen, E. Anderson, H. Chapman, J. Kirz, S. Lindaas, M. Rivers, S. Wang, S. Williams, S. Wirick, and X. 

Zhang, "The X-I A Scanning Transmission X-ray Microscopc: Optics and Instrunicntation", edited by V. V. 

Aristov and A. I. Erko, X-rav Microscopy IV. Bogorodskii Pechatnik. Procecdincs ofthe International Confer- 

ence. Chernogolovka. Russia. September 20-24, pp. 304-32 1, (1 993). 

C. Jacobsen, J. Fu, Y. Wang, and S. Williams, "Scanning Luminescence X-ray Microscopy: Progrcss Towards 

Selective Stainingusing Microspheres", edited by G. W. Bailey and A. J. Garratt-Reed, Proceedinrs ofthe 52 

Annual Meeting ofthe Microscopy Society ofAmerica, San Francisco Prcss, pp. 74-75, (1 994). 

J. Kirz, H. Ade, R. E. Botto, G. D. Cody, J. Fu, C. Jacobsen, S. Lindaas, W. F. Mangel, W. J. McGrath, V. 

Oehler, J. van't Hof, S. Williams, S. Wirick, and X. Zhang, "Scanning Transmission X-ray Microscopy at thc 

NSLS", edited by V. V. Aristov and A. I. Erko, X-ray Microscopy IV, Bogorodskii Pechatnik. proceed in^.^ ofthe 

International Conference, Chcrnogolovka. Russia. September 20-24, pp. 41 -6 1, ( 1993).

J. Kirz, H. Ade, C. Jacobsen, C. H. KO, S. Lindaas, S. Williams, andX. Zhang, "Soft X-ray Microscopy-Physical 

Basis and Recent Developments", Proceedings of the Fifth Asia-Pacific Physics Conference, World Scientijic, 1, 

pp. 200-215, (1994). 

J. Kirz, C. Jacobsen, S. Lindaas, S. Williams, X. Zhang, E. Anderson, and M. Howells, "Soft X-ray Microscopy at 

the National Synchrotron Light Source", edited by B. Chance, D. Deisenhober, S. Ebashi, D. T. Goodhead, J. R. 

Helliwell, H. E. Huxley, T. Iizuka, J. Kirz, T. Mitsui, E. Rubenstein, N. Sakabe, T. Sasaki, G. Schmahl, H. 

Sturhmann, K. Wiithrich, and G. Zaccai, Synchrotron Radiation in Biosciences, Clarendon Press, Oxford, pp. 

563-571, (1994). 

C.-H. KO, Development of a Second Generation Scanning Photoemission Microscope at the National Synchro- 

tron Light Source, PhD Thesis, Department of Physics, State University ofNew York at Stony Brook, (1995). 

S. A. Lindaas, X-ray Gabor Holography using a Scanning Force Microscope, PhD Thesis, Department of hysics, 

State University ofNew York at Stony Brook, (1994). 

S. Lindaas, C. Jacobsen, A. Kalinovsky, and M. Howells, "X-ray Gabor Holography: Recent Progress", edited by 

G. W. Bailey and A. J. Garratt-Reed, Proceedings ofthe 52 Annual Meeting ofthe Microscopy Society of 

America. San Francisco, SanFrancisco Press, pp. 72-73, (1994). 

S. Lindaas, M. Howells, C. Jacobsen, and A. Kalinovsky, "X-ray Holographic Microscopy by means of Photoresist 

Recording and Atomic-Force Microscope Readout", J. of Opt. Soc. ofAm., A13/9,1788- 1800, (1 996). 

B. W. Loo, Jr., S. Williams, W. T. Lin, W. H. Love, S. Meizel and S. S. Rothrnan, "High Resolution X-ray 

Stereomicroscopy: True Three-Dimensional Imaging of Biological Samples", edited by C. Jacobsen and J. Trebes, 

Soft X-ray Microscopy, SPIE, 1741,392, (1992). 

K. Maier, Characterization of a Scanning Photoemission Microscope, M.A. Thesis, Department of Physics, State 

University of New York at Stony Brook, (1 995). 

I. McNulty, J. Kirz, C. Jacobsen, M. R. Howells and E. Anderson, "First Results with a Fourier Transform 

Holographic Microscope", editedby A.G. Michette, G.R. Morrison, and C. J. Buckley, X-ray Microscopy 111, 

SDringer., 

67,pp. 251-254, (1992). 

M.M. Moronne, C. Larabell, P.R. Selvin, and A. Irtel von Brenndorff, "Development ofFluroescent Probes for 

X-ray Microscopy", edited by G.W. Bailey and A.J. Garratt-Reed, Proceedings ofthe 52 Annual Meeting of the 

Microscopy Society ofAmerica, San Francisco Press, pages 48-49, (1 994). 

G. R. Morrison, "X-ray Imaging with a Configured Detector", edited by V. V. Aristov and A. I. Erko, X-ray 

Microscopy IV. Bogorodskii Pechatnik. Proceedings ofthe 4~ International Conference. Chernogolovka. Russia, 

September 20-24, pp. 478-486, (1994). 

A. Osanna, C. Jacobsen, A. Kalinovsky, J. Kirz, J. Maser, and S. Wang, "X-ray Microscopy: Preparations for 

Studies ofFrozen Hydrated Specimens", ScanningMicroscopy, 10,349-358, (1 996). 

E. G. Rightor, A. P. Hitchcock, H. Ade, R. D. Leapman, S. G. Urquhart, A. P. Smith, G. Mitchell, D. Fischer, 

H. J. Shin, and T. Warwick. "Spectromicroscopy of Poly(ethy1ene terephthalate): Comparison of Spectra and 

Radiation Damage Rates in X-ray Absorption andElectron Energy Loss", J. ofPhys. Chem., B101/11,1950- 

1960, (1997).

A. P. Smith, Characterization ofthc Lateral Oricntation within Poly(p-phenylcne terephtlialamide) (Kevlar) 

Fibers and the Microchemistry ofMethylene Diphenyl Diisocvanate (MDI) based Polvurcthane foams witli X-ray 

Microscopy, M.S. Thesis, Materials Science and Engineering, North Carolina State University, (1 995). 

A. P. Smith and H. Ade, "Quantitative Orientational Analysis ofa Polynieric Material (Kevlar tibcrs) with X-ray 

Microspectroscopy", Appl. PIIJLT. Letts., 69,3833-3835, (1 996). 

A. P. Smith, J. H. Laurer, H. W. Ade, S. D. Smith, A. Ashraf, and R. J. Spontak. "X-ray Microscopy and 

NEXAFS Spectroscopy of Macrophase-Separated Random Block CopolynierIHoniopolymer Blcnds", Mtrcwrtlol- 

ecules, 30,663-666, (1997). 

S. J. Spector, Diffractive Optics for Soft X-rays, PhD Thesis, Department of Physics, State Univcrsity of Ncw 

York at Stony Brook, (1997). 

Y. Wang and C. Jacobsen, "Modelling ofDissolution and Rcsolution in Contact X-ray Microscopy", cditcd by 

G.W. Bailey and A.J. Garratt-Reed, Proceedings ofthe 52 Annual Meeting ofthc Microscopy Socicty of America, 

San Francisco, San Francisco Press, pp. 62-63, (1 994). 

M. Wei, D.T. Attwood, T.K. Gustafson, and E.H. Anderson, "Patterning a 50-nm Period Grating using Soft X- 

ray Spatial Frequency Multiplication", J. Vac. Sci. arid Tech., 1216,3648-3652, (1994). 

S. Williams, C. Jacobsen, J. Kirz, S. S. Lamm, J. van't Hof, and X. Zhang, "Metaphase Chromosome DNA Mass 

Fraction is Independent of Species", edited by G.W. Bailey and A.J. Garratt-Reed, Proceedincs ofthe 52 Annual 

Meeting ofthe Microscopy Society of Anierica. San Francisco, San Francisco Prcss, pp. 46-47, ( 1994). 

S. Williams, C. Jacobsen, J. Kirz and X. Zhang, "Imaging with the Brookhaven Scanning Transmission X-ray 

Microscope", edited by J.M. Schnur and M. Peckerar, Synthctic Microstructures in Biolocical Rcscarch, Plcnum 

Press, pp. 109- 1 19, (1992). 

B. Winn, H. Ade, C. Buckley, M. Howells, S. Hulbert, C. Jacobsen, J. Kirz, I. McNulty, J. Miao, T. Oversluizen, 

I. Pogorelsky, and S. Wirick, "X1 A: Second Generation Undulator Beamlines Serving Soft X-ray 

Spectromicroscopy Experiments at the NSLS", Re\?. Sci. Iristrxnl., 6719,l-4, ( 1996). 

B. Winn, X. Hao, C. Jacobsen, J. Kirz, J. Miao, S. Wirick, H. Adc, C. Bucklcy, M. Howclls, S. Hulbcrt, I. 

McNulty, and T. Oversluizen. "Considerations for a Soft X-ray Spcctromicroscopy Beamline", cditcd by L. E. 

Berrnan and J. Arthur, Optics for High-Brightness Synchrotron Radiation Beanilines 11, SPIE, 2856, 100- 109, 

(1 996). 

X. Zhang, Development and Applications ofouantitative X-ray Microscopy witli Chemical Sensitivity, PhD 

Thesis, Department of Physics, State University of New York at Stony Brook. ( 1995). 

X. Zhang, R. Balhorn, C. Jacobsen, J. Kirz, and S. Williams, "Mapping DNA and Protein in Biological Samplcs 

using the Scanning Transmission X-ray Microscope", edited by G.W. Bailey and A.J. Garratt-Reed, Proceedings 

ofthe 52 Annual Meeting of the Microscopy Socicty of Amcrica, San Francisco, San Francisco Prcss, pp. 50-5 1, 

(1 994). 

Beamline XI B 

B. Kempgens, A. Kiviniaki, H.M. Kuppe, M. Neeb, A.M. Bradshaw, and J. Feldhaus, "One-Electron vs. Multi- 

Electron Effects in the Near-Thrcshold C 1 s Photoionisation ofAcctylcnen, J. Cl~cnl. PIIJ-s.., 107,42 19-24, 

(1 997).

i B. Kempgens, A. Kivimaki, M. Neeb, H.M. Kuppe, A.M. Bradshaw, and J. Feldhaus, "A High-Resolution N Is 

Photoionization Study of the N, Molecule in the Near-Threshold Region", J. Phys., B29,5389-5402, (1996). 

B. Kempgens, H.M. Kuppe, A. Kivimaki, M. Neeb, K. Maier, U. Hergenhahn, and A.M. Bradshaw, "A Re- 

appraisal of the Existence of Shape Resonances in the Series C,H2, C,H, and C,H,", Phys. Rev. Lett., 79,35-38, 

(1997). 

A. Kivimaki, B. Kempgens, K. Maier, H.M. Kuppe, M.N. Piancastelli, M. Neeb, and A.M. Bradshaw, "The 

Vibrational Resolved 0 1 s Photoelectron Spectrum of CO,: Vibronic Coupling and Dynamic Core-hole Local- 

ization", Phys. Rev. Lett., 79,998-1001, (1997). 

A. Kivimaki, M. Neeb, B. Kempgens, H.M. Kuppe, K. Maier, and A.M. Bradshaw, "Angle-Resolved Auger 

Spectra of C2N, Molecule", J. Phys., B30,4279-9 1, (1 997). 

M. Neeb, A. Kivimaki, B. Kempgens, H.M. Kuppe, and A.M. Bradshaw, "The C 1s Auger Decay Spectrum of 

CF,: an Analysis of the Core-Excited States", J. Phys., B30,93- 100, (1 997). 

S.H. Overbury, D.R. Huntley, D.R. Mullins, K.S. Ailey, andP.V. Radulovic, "Surface Studies of Model Sup- 

ported Catalysts: NO Adsorption on Rh/Ce0,(00 I)", J. Vac. Sci. Technol., AlS,l647, (1 997). 

M.N. Piancastelli, A. Kivimaki, B. Kempgens, M. Neeb, K. Maier, and A.M. Bradshaw, "High-Resolution Study 

of Resonant Decay Following the 0 1 s 7c Excitation in CO,: Evidence for an Overlapping Rydberg Transition", 

Chem. Phys. Lett., 274,l3, (1997). 

M.N. Piancastelli, M. Neeb, A. Kivimaki, B. Kempgens, H.M. Koppe, K. Maier, and A.M. Bradshaw, "Variation 

of Cross-Section Enhancement in Decay Spectra of CO under Resonant Raman Conditions", Phys. Rev. Lett., 77, 

4302-4305, (1996). 

Beamline X2A 

R. Paniago, T.H. Metzger, J. Trenkler, R. Hempelmann, H. Reichert, S. Schmid, P.C. Chow, S.C. Moss and J. 

Pelsl, "Near-Surface Tricritical Behavior ofV,H(O 10) at the P,-P, Phase Transition", Phys. Rev. BriefReports, 56, 

16, (1997). 

H. Reichert, S.C. Moss, and K.S.Liang, "Anomalous Temperature Dependence ofthe X-ray Difhse Scattering 

Intensity of Cu3AuV, Phys. Rev. Lett., 77,4382, (1996). 

H. Reichert, S.C. Moss, and K.S. Liang, "Reply to Comment by V. Ozollns, et.al.", Phys. Rev. Lett., 79,956, 

(1997). 

H. Reichert, I. Tsatskis, and S.C. Moss, "Temperature Dependent Microstructure of Cu3Au in the Disordered 

Phase", NSFJCNRS Workshop on Alloy Theory, Comput. Muter. Sci., 8,46, (1997). 

Beamline X3Al 

R. Bolotovsky, and P. Coppens, "The @-extent of the Reflection Range in the Oscillation Method According to 

the Mosaicity Cap Model",J. Appl. Cryst., 30,65, (1997). 

R. Bolotovsky, and P. Coppens, "The "Seed-Skewness" Method for Integration of Peaks on Imaging Plates 11: 

Analysis of Bias due to Finite Size of the Peak Mask and Treatment of a,-a, Splitting", J. Appl. Cryst., 30,244, 

(1997).

C.L. Cahill, and J.B. Parise, "The Synthesis and Structure of MnGe,Sl,,.(C,Hl,N,).3~I,0: A Novcl Sulfidc 

Framework Analogous to Zeolite-A(BW)", Clieni. Muter., 9,8 12, (1 997). 

J. Chen, R. Li, J.B. Parise, and D.J. Weidner, "Pressure Induced Ordcring in NiMg-Olivine", Am. Miricrul, 81, 

15 19, (1996). 

P. Coppens, "Time-Resolved Diffraction in Chemistry and Materials Science: the Developing Field of 

Photoc~ystallography", Sjwch. Rud. News, 10/1,26, (1 997). 

A. Darovsky, V. Kezerashvili, P. Coppens, T. Weyhcnniillcr, H. Hunimcl, and K. Wicghardt, "Temperaturc- 

Dependent Electron Transfer in a Mn"Mnl"(y -OH) Mixed-Valence Manganese Complcx", 1rior.g. Chcn~., 35, 

69 16, (1 996). 

C. Eylem, J.A. Hriljac, D.R. Corbin, and J.B. Parise, "Structure of a Zeolite ZSM-5-Bithiophcnc Complex as 

Determined by High Resolution Synchrotron X-ray Powder Diffraction", Chcn~. Muter.., 8,844, (1 996). 

M. Kunz, K. Leinenweber, J.B. Parise, T.-C. Wu, W.A. Bassett, K. Brister, D.J. Weidncr, M.T. Vaughan, and Y. 

Wang, "The Baddeleyite-Type High Prcssurc Phase ofCa(OH),",,J. High P~ms Rev., 14,3 1 1, ( 1996). 

M. Kunz, D. Xirouchakis, Y. Wang, J. B. Parise, and D.H. Lindslcy, "Structural Investigations along tlic Join 

CaTiOSiO, - CaSnOSiO,", Swi.s.s Bzrll. Min. Pet., 77, 1, (1 997). 

J.B. Parise, Y. Wang, G.D. Gwanmesia, J. Zhang, Y. Sinelnikov, J. Chmiclowski, D.J. Weidncr, and R.C. 

Lieberniann, "The Symmetry of Garnets on the Pyrope (Mg,A,,Si,O,,)-Majoritc (MgSiO,) Join", Gcop1iv.s. Rev. 

Lett., 23,3799, (1996). 

K. Prassides, K. Vavekis, K. Kordatos, K. Tanigaki, G.M. Bendelc, and P.W. Stcphcns, "Loss ofCubic Symmetry 

in Low Temperature Na,RbC ,,, ", J. Ante/.. Cheni. Soc., 11 9,834, ( 1997). 

K. Tan, Y. KO, J.B. Parise, J.-H. Park, and A. Darovsky, "ANovel Antimony Sulfied Ternplated by 

Diniethylammonium: Its Synthesis and Structural Characterization using Synchrotron Imaging Platc Data", 

Chem. Muter.., 8,25 10, (1 996). 

Beamline X3A2 

T. Dobashi, M. Takenaka, F. Yeh, G. Wu, K. Ichikawa, and B. Chu, "Scattcring Studies of Poly(urca-urctlia~ic) 

Microcapsule in Suspension", J. Coll. & Iiite/fuceSci., 179,640, (1 996). 

L. Liu, F. Yeh, and B. Chu, "Synchrotron SAXS Study ofCrystallization and Microphase Separation in Compat- 

ible Mixturcs ofTetrahydrofuran-Methyl Methacrylate Diblock Copolynier and Polytctrahydrofilran", Mucr.omo1- 

ecules, 29,5336, (1 996). 

E.L. Sokolov, F. Yeh, A.R. Khokhlov, and B. Chu, "Nano-Scale Supraniolccular Ordcring in Gel-Surfactant 

Complexes: Sodium Alkyl Sulfates in Poly(diallydimethylan1moniun7 Chloridc)", Lrrnpiii~ir., 26,6229, (1 996). 

F. Yeh, E.L. Sokolov, A.R. Khokhlov, and B. Chu, "Nano-Scale Supraniolccular Structures in Gels of 

Poly(diallyldimethy1ammonium chloride) Interacting with Sodium Dodecyl Sulfatc",.J. Am. Clicvii. Soc., 118, 

6615, (1996).

Beamline X3B1 

D. Balzar, P.W. Stephens, and H. Ledbetter, "Synchrotron X-ray Diffaction Line Profile", Fizika, A6,4 1, (1 997). 

D. Balzar, P.W. Stephens, H. Ledbetter, J. Li, and M.L. Dunn, "Synchrotron X-ray Diffraction Study of the 

Surface Layer in Poled Ceramic BaTiO,", Mat. Res. Soc. Symp. Proc., 453,7 15, (1 997). 

S.D. Bohle, R.E. Dinnebier, S.K. Madsen, and P.W. Stephens, "Characterization of the Products of the Heme 

Detoxification Pathway in Malarial Late Trophozoites by X-ray Diffraction", J. Biol. Chem., 272,7 13, (1 997). 

C.L. Cleveland, U. Landman, T.G. Schaaff, M.N. Shafigullin, P.W. Stephens, and R.L. Whetten, "Structural 

Evolution of Smaller GoldNanocrystals: The Truncated Decahedral Motif ', Phys. Rev. Letts., 79,1873, (1 997). 

C.L. Cleveland, U. Landman, M.N. Shafigullin, P.W. Stephens, and R.L. Whetten, "Structural Evolution of 

Larger Gold Clusters", Zeitschriftfur Physik, D40,153, (1 997). 

R.E. Dinnebier, F. Olbrich, and G.M. Bendele, "Cyclopentadienyl Cesium by High-Resolution X-ray Powder 

Diffraction", Acta Cryst., C53,699, (1997). 

R.E. Dinnebier, F. Olbrich, S. van Smaalen, and P.W. Stephens, "The Ab Initio Structure Determination of Two 

Polymorphs of Cyclopentadienyl Rubidium in a Single Powder Pattern", Acta Cryst., B53,153, (1 997). 

R.E. Dinnebier, M. Pink, J. Sieler, and P.W. Stephens, "Novel Alkali Metal Coordination in Phenoxides: Powder 

Diffraction Results on C6H,0M [M = Li, Na, K, Rb, Cs]", Inorg. Chem., 36,3398, (1997). 

W.C. Elliott, P.F. Miceli, T. Tse, and P.W. Stephens, "Temperature and Orientation Dependence of Kinetic 

Roughening During Homoepitaxy: a Quantitative X-ray Scattering Study of Ag", Phys. Rev., B54,17938, (1996). 

S.W. Huang, Z.H. Ming, Y.L. Soo, Y.H. Kao, M. Tanaka, and H. Munekata, "X-ray Scattering and Absorption 

Studies of MnAs Thin Films Grown by MBE on GaAs(OO1) Substrates", Evolution of Epitaxial Structure and 

Morphology, Mat. Res. Soc. Symp. Proc., 399,29, (1996). 

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Beamline X5 

K. Hicks, H. Baghaci, A. Caracappa, A. Cichocki, G. Davenport, R. Finlay, V. Gladyshcv, T. Gresko, S. Hoblit, 

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Beamline X6B 

R.P. Chiarello, N. C. Sturchio, J. Grace, P. Geissbuhler, L. Sorensen, L. Cheng, and S. Tau, "Otavite-calcite 

Solid-Solution Formation at the Calcite-water Interface Studied in sit11 by Synchrotron X-ray Scattering", 

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S. Krishnan, J.J. Felten, J.E. Rix, J.K.R. Weber, P.C. Nordine, M.A. Beno, S. Ansell, and D.L. Price, "Levitation 

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A. Malik, M.K. Durbin, A.G. Richter, K.G. Huang, and P. Dutta, "Order in Langnluir-Blodgett Films of Lcad 

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Beamline X7A 

P. Armand, A. Goldbach, C. Cran~er, R. Csencsits, L. E. Iton, D. L. Price, and M.-L. Saboungi, "Semiconduetors 

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P. Amland, M.-L. Saboungi, D. L. Price, L. Iton, C. Cranier, and M. Grimsditch, "Nanoclustcrs in Zcolitc", 

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C. L. Bowes, W. U. Huynh, S. J. Kirby, A. Malek, G. A. Ozin, S. Petrov, M. Twardowski, D. Younc, R. L. 

Bedard, and R. Broach, "Dimctal inked Open Frameworks: [(CH,),N],(Ag,,Cu,)GeS,,,", 

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D. J. Buttrey, T. Vogt, G. P. A. Yap, and A. L. Rheingold, "The Structure of Bi,,Mo,,,O ,,, ", Mrrtci.. Rcs. Bull., 

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D.G. Castncr, P. Favia, and B.D. Ratner, "Deposition of Fluorocarbon Films by Remote RF Glow Discharge", 

Surface Modification of Polymeric Bion~aterials, Edited by B.D. Ratncr and D.G. Castncr, Plenum Press, New 

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L. Chai, M. A. Akbas, P. K. Davies, and J. B. Parisc. "Cation Ordering Transformations in Ba(Mg, ,Ta, ,)O,- 

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D. E. Cox, and R. J. Papoular, "Structure Refinement with Synchrotron Data: R-factors, Errors and Significance 

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Y. Fei, C. M. Bertka, and L. W. Finger, "High-pressure Iron-Sulfur Compound, Fe3S2, and Melting Relations in 

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C. C. Freyhardt, R. F. Lobo, S. Khodabandeh, J. E. Lewis Jr., M. Tsapatsis, M. Yoshikawa, M. A. Camblor, M. 

Pan, M.M. Helmkamp, S. I. Zones, andM. E. Davis, "VPI-8: A High-Silica Molecular Sieve with aNovel 

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R. L. Harlow, N. Herron, and D. L. Thorn, "The Crystal Structures of some New Forms of Aluminum Fluoride 

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M. Kunz, D. Xirouchakis, Y. Wang, J.B. Parise, and D.H. Lindsley, "Structural Investigations along the Join 

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L.H. Lewis, C.H. Sellers, and V. Panchanathan, "Factors Affecting Coercivity in Rare-Earth-Based Advanced 

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D. L. Price, A. J. G. Ellison, M.-L. Saboungi, R.-Z. Hu, T. Egami, and W. S. Howells, "Short, Intermcdiatc-and 

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P. G. Radaclli, D. E. Cox, M. Marczio, and S.-W. Chcong, "Charge, Orbital and Magnetic Ordering in 

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M. R. Stetzcr, P. A. Heiney, J. E. Fischcr, and A. R. McGhie, "Thcniial Stability of Solid C ,,, ", 

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J. Vacinova, J. L. Hodeau, P. Bordct, M. Anne, D. Cox, A. Fitch, P. Pattison, W. Schwegglc, H. Graafsma, and 

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W. Wang, D.G. Castner, and D.W. Graingcr, "Ultrathin Filnis of Pcrfluoropo1yctIicr-Grafted Polysiloxancs 

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P. M. Woodward, A. W. Sleight, and T. Vogt, "Fcrroclcctric Tungsten Trioxidc",.J. SoIidStuic Clicrii., 131,9, 

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D. Xirouchakis, M. Kunz, J.B. Parise, and D.H. Lindslcy, "Synthesis Methods and Unit-Cell Volumc of End- 

Member Titanite (CaTioSio,)", Aniericna Miner-alngist, 82,748- 753, (I 997). 

Q. Zhu, L. Li, M. S. Masteller, and G. J. Dcl Corso, "An Increase of Structural Ordcr Paranictcr in Fc-Co-V 

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Beamline X7B 

J. Aizenbcrg, J. Hanson, T.F. Koetzle, S. Weiner, and L. Addadi, "Control of Macromolecule Distribution within 

Synthetic and Biogenic Single Calcite Crystals", J. Am. Chn)~. Sor., 119, 881, (1997). 

G. Artioli, K. Stihl, and J.C. Hanson, "The Dehydration Process in the Natural Zeolite Laumontite: A Rcal- 

Time Synchrotron X-Ray Powder Diffraction Study", Mdtel: Sri. Foriim, 228, 369, ( 1 936). 

R. Bolt, J. Albertsson, G. Svensson, K. Stihl, and J.C. Hanson, "A Synchrotron X-Ray Study of Fcrroclcctric 

Switching, Domain Reversal and Piezoelectric Moduli in CsTiOAsO, under an Applied Electric Fi~ld",~ Ap/d 

Cyst., 30, 383, (1997) 

A. N. Christensen, P. Norby, and J. C. Hanson, "In Sit11 Investigation of Magnesium Aluminophosphatc Synthc- 

sis by Synchrotron X-Ray Powdcr Diffraction", Acia Cl?erii. Scarid., 51,249, ( 1 997). 

A.N. Christensen, P. Norby, and J.C. Hanson, "Superconducting Cuprates and Related Oxides. IX. 111 Situ 

Synchrotron X-Ray Powder Diffraction Investigation of the Oxidation and Reduction of YBa,Cu,07-, in a Flow 

of Oxygen or of Nitrogen Gas in the Temperature Range 400-725OCv, Actd Chrmird Scmdir~nvir/r, 51, 340, 

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A. N. Christensen, P. Norby, J. C. Hanson, and S. Shimada, "Phase Transition of KN,,, Monitored by Synchrotron 

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M.J. Gray, J.D. Jasper, A.P. Wilkinson, and J.C. Hanson, "Synthesis and Synchrotron Microcrystal Structure of 

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C.P. Grey, F.I. Poshni, A. Gualtieri, P. Norby, J.C. Hanson, and D.R. Corbin, "Combined MAS NMR and X- 

ray Powder Diffraction Structural Characterization of Hydrofluorocarbon- 134 Adsorbed on Zeolite Nay: Obser- 

vation of Cation Migration and Strong Sorbate-cation Interactions", J. Am. Chem. Soc., 119, 198 1, (1 997). 

A. Gualtieri, P. Norby, G. Artioli, and J. Hanson, "Kinetics of Formation of Zeolite Na-A [LTA] from Natural 

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A. Gualtieri, P. Norby, G. Artioli, and J. Hanson, "Kinetic Study of ~ydroxysodalite ~olmation from 

Natural Kaolinites by Time-Resolved Synchrotron Powder Diffraction", Mi croporous Materials, 9, 189, 

(1997). 

A. Gualtieri, P. Norby, J. Hanson, and J. Hriljac, "Rietveld Refinement using Synchrotron X-ray Powder Diffrac- 

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T. Hanninen, I. Mutikainen, V. Saanila, M. Ritala, M. Leskel, and J.C. Hanson, "[Ca(Thd),(Tetraen)]: A 

Monomeric Precursor for Deposition of CaS Thin Films", Chem. Mat., 9, 1234, (1997). 

R.A. Holroyd, J.M. Preses, and J.C. Hanson, "Excited Singlet State Yields in Hydrocarbon Liquids Exposed to X- 

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R.E. Morris, S.J. We$, P. Norby, J.C. Hanson, and A.K. Cheetham, "In Situ Single-Crystal X-ray Diffraction 

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J.B. Parise, K. Tan, P. Norby, Y. KO, and C. Cahill, "Examples of Hydrothermal Titration and Real Time X-ray 

Diffraction in the Synthesis of Open Frameworks", Mat. Res. Soc. Symp. Proc., 453, 103, (1997). 

K. StM, G. Artioli, and J.C. Hanson, "The Dehydration Process in the Zeolite Laumontite: A Real-Time 

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Beamline X8A and X8C 

J.J. Fitch, R.L. Blake, A.J. Burek, A.M. Clark, D.E. Graessle, B. Harris, D.A. Schwartz, and J.B. Sweeney, "AXAF 

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D.E. Graessle, A.J. Burek, J.J. Fitch, B. Harris, D.A. Schwartz, and R.L. Blake, "Optical Constants from Synchro- 

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P. J. Loll, A. E. Bevivino, B. D. Korty, and P. H. Axclscn, "Simultancous Recognition ofa Carboxylatc-contain- 

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Beamline X9A 

B. Sclavi, S. Woodson, M.R. Chancc, and M.D. Brcnowitz, "Examining thc Conformational Dynamics of 

Macromolecules with Tinic-Rcsolvcd X-Ray ' Footprinting' ", Str.~-llrr~, 5,865-869, ( 1997). 

B. Sclavi, S. Woodson, M. Sullivan, M.R. Chancc, and M. Brcnowitz. "Timc-Rcsolvcd Synchrotron X-Ray 

'Footprinting', a Ncw Approach to the Study of Nucleic Acid Structurc and Function: Application to Protcin- 

DNA Interactions and RNA Folding", J. Mol. Biol., 266, 144- 159, (1 997). 

B. Sclavi, S. Woodson, M. Sullivan, M.R. Chancc, and M.D. Brcnowitz, "X-Ray ' Footprinting' Analysis ofthc 

Mg2' Depcndcnt Folding ofthc Tetrahymena Thcrniophila Ribozyme", Pi.og, iii Rioph. & Moloclrlrrr Biolop, 65, 

85, (1 996). 

B. Sclavi, S. Woodson, M. Sullivan, M.D. Brcnowitz, and M.R. Chancc, "Kinetics of Folding of thc Tctrahy- 

niena Thcrniophila Group I Intron", Bioplij:vical.J., 72, A422, ( 1997). 

David L. Tierncy, XAS Charactcrization of Bacterial Superoxide Dismutasc and NMR Charactcrization of 

Substrate Binding in Phthalate Dioxygenase, Ph.D. Thcsis, University ofMicligian, ( 1996). 

Beamline X9B 

S.C. Goldsmith, N. Pokala, P. Matsudaira, and S.C. Aloni, "Crystallization and Preliminary Crystallograpliic 

Analysis ofthc N-tcrniinal Actin Binding Domain of Hunian Finibrin", Protciris: Str.lrctltr.c, F~rnc~ioii R. Gcilcticx, 

28,452-453, (1 997). 

J.C. Gonzalcz, K. Pcariso, J. Pcnncr-Hahn. and R.G. Matthcws, "Cobalamin-Indcpcndcnt Mcthioninc Synthasc 

from Escherickin coli: A Zinc Metalloenzyme", Biochcni., 35,12228- 12234, (1 996). 

Z. Gu, J. Dong, C.B. Allan, S.B. Choudhury, R. Franco, J.J.G. Moura. I. Moura. J. LcGall, A.E. Przybyla, W.R. 

Roscboom, S.P.J. Albracht, M.J. Axley, R.A. Scott, and M.J. Maroncy, "Structurc ofthc Ni Sitcs in Hydrogcna- 

ses by X-Ray Absorption Spectroscopy. Species Variation and the Effects of Redox Poise", J. Ani. Clicni. Soc., 

118, 11 155-1 1165, (1996). 

P. Henderson, D. Beycr, U. Jonas, 0 . Karthaus, H. Ringsdorf, P.A. Heincy, N.C. Maliszcwskyj, S.S. Ghosh, 0. 

Mindyuk, and J.Y. Joscfowicz, "Complex Ordering in Thin Films of Di-and Trifilnctionalizcd tlcxaalkoxy 

Triphenylenc Dcrivativcs", J. Ani. Clieni. Soc., 119,4740-4748, (1 997). 

K.C. Holnies, "The Swinging Levcr-Arm Hypothesis of Musclc Contraction", Clri~ciit Biolog, 7, R 1 12- 1 18, 

(1 997). 

K.C. Holnies, "Muscle Proteins: Their Actions and Interactions", Czrr.i*ciit Opiiiioii in Str.rrctrtr.crl Biolog~: 6,78 1 - 

789, (1 996). 

H. Huang, Structural Charactcrization of0rganocopper Reazcnts, PhD. Thesis, University of Michigan, 

(1 997). 

H.C. Lee, E.M. Scheuring, J. Peisach, and M.R. Chance, "ESEEM and EXAFS Studics of Modcls of0xyCo-

I 

Substituted Hemoproteins: Correlating Electron-Nuclear Interactions and Metal-Ligand Bond Lengths", Bio- 

physicalJ., 72, A427, (1997). 

S. Mahapatra, J. A. Halfen, E. C. Wilkinson, G. Pan, X. Wang, V. G. Young, Jr., C. J. Cramer, L. Que, Jr. and 

W. B. Tolman, "Structural, Spectroscopic, and Theoretical Characterization of Bis(m-oxo)dicopper Complexes, 

Novel Intermediates in Copper-Mediated Dioxygen Activation", J. Am. Chem. Soc., 118,11555- 1 1574, (1 996). 

M. J. Maroney, C. B. Allan, S. B. Choudhury, and Z. Gu, "Redox Metalloenzymes with S-donor Ligands. 

Hydrogenase: A Case Study", Transition Metal Sulfur Chemistry: Biological andIndustria1 Significance, edited 

by E. I. Stiefel and K. Matsumoto, ACSSymposium Series, 653,74-100, (1996). 

L.M. Miller, A.J. Pedraza, and M.R. Chance, "Identification of Conformational Substrates Involved inNitric 

Oxide Binding to Ferric and Ferrous Myoglobin Through Difference Fourier Transform Infrared Spectroscopy", 

BiophysicalJ., 72, A425, (1997). 

M.J. Nelson, L.T. Durney, and R.C. Scarrow, "Nitrile Hydratase from Rhodococcus rhodochorous J1 Contains a 

Non-Corrin Cobalt Ion with Two Sulfur Ligands", J. Amer. Chem. Soc., 115,9 194-9 195, (1996). 

F. Schlunzen, H.A.S. Hansen, J. Thygesen, N. Volkrnann, I. Levine, J. Harrnes, H. Bartels, A. Bashan, Z. 

Berkovitch-Yellin, I. Sagi, F. Franceschi, S. Krumbholz, M. Geva, S. Weinstain, I. Agmon, N. Boddejer, S. 

Morlang, R. Sharon, A. Dribin, M. Peretz, V. Weinrich, and A.Yonath, "A Milestone in Ribosomal Crystallogra- 

phy: The Construction of Preliminary Electron Density Maps at Intermediate Resolution", Biochem & Cell Biol., 

73, 739, (1996). 

L. Shu, Y. Liu, J.D. Lipscomb, and L..Que, Jr., "X-Ray Absorption Spectroscopic Studies ofthe Methane 

Monooxygenase Hydroxylase Component from Methylosinus Trichosporium 0B3b7', J. Bioinorganic Chem., 1, 

297-304, (1996). 

L. Shu, J.C. Nesheim, K. Kauffmann, E. Miinck, J.D. Lipscomb, and L. Que, Jr. "An Fe202 Diamond Core 

Structure for the Key Intermediate Q of Methane Monooxygenase", Science, 25,5 15-5 18, (1997). 

I D.L. Tierney, XAS Characterization of Bacterial Suueroxide Dismutase andNMR Characterization of Substrate 

I 

Binding in Phthalate Dioxyyenase, PhD. Thesis, University of Michigan, (1 996). 

I 

i 

~ 

I 

H. Wang, G. Peng, L.M. Miller, E.M. Scheuring, S.J.George, M.R. Chance, and S.P. Cramer, "Iron L-edge X- 

ray Absorption Spectroscopy ofMyoglobin Complexes and Photolysis Products", J. Amer. Chem. Soc., 119, 

492 1-4928, (1 997). 

X. Wang, C. R. Randall, and L. Que, Jr., "X-ray Absorption Spectroscopic Studies of an FeZn Derivative of 

Uteroferrin", Biochemistry, 35,13946-1 3954, (1996). 

K. Zhang, A.M. Edwards, J. Dong, J.A. Chupa, and J.K. Blasie, "XAFS on Vectorially-oriented Single Monolayer 

Protein Samplesn,J. de Phys. IVColloque, 7, C2-593-C2-597, (1997). 

Beamline XlOA 

I P. Fenter, A. Eberhardt, K.S. Liang, and P. Eisenberger, "Molecular Epitaxy and Strain in Self-Assembled Monolayers7',J. 

Chem. Phys., 106,1600, (1997). 

P. Fenter, F. Schreiber, L. Zhou, P. Eisenberger, and S.R. Forrest, "In Situ Studies of Morphology, Strain, and 

Growth Modes of a Molecular Organic Thin Film", Phys. Rev., B56,3046, (1997).

Beamline X1OB 

J. Li, and H.D. Abruna, "Coadsorption of SulfateIBisulfatc Anions with Hg Cations During Hg Undcrpotcntial 

Deposition on Au(l 1 1): An Jri Situ X-ray Diffraction Study", J. P1ij.s. Clicwi., B101,24-252, (1 997). 

Beamline XlOC 

P. Schmuki, S. Virtanen, A. J. Davenport, and C. M. Vitus, "Iri situ X-ray Absorption Ncar-edgc Spectroscopic 

Study ofthe Cathodic Reduction ofArtifical iron Oxide Passive Films", J. EIcctrm-hcni. Soc., 14312,574-582, 

(1 996). 

P. Schmuki, S. Virtanen, A. J. Davenport, and C. M. Vitus, "Transpassive Dissolution ofCr and Sputtcr- 

Deposited Cr Oxides Studied by in sit11 X-ray near edge Spectroscopy", J. Elcctr~ochcni. Soc., 143,3997, (I 996). 

P. Schmuki, S. Virtanen, H.S. Isaacs, A.J. Davenport, H. Bohni, and T. Stenberg. "Jri .situ XANES Stidics on thc 

Electrochemical Behavior of Thin (Fe,Cr)-oxide Films used as Models for Passivc Films", Surfacc Oxidc Films, 

edited by J. Bardwell, Elect~~ocheniicnlSoc., 9611 8,234, (1 996). 

S. Virtanen, P. Schmuki, A. J. Davenport, and C.M. Vitus, "Dissolution of Artificial Iron Passivc Films Studicd 

by in situ X-ray Absorption ncar Edgc Spectroscopy",J. Electr.ochcni. Soc., 144,198, (1 997). 

S. Virtanen, P. Schmuki, A. J. Davenport, and C.M. Vitus, "Dissolution of Sputter-Dcpositcd Iron Oxidc films 

used as a Model for the Passive filni on Iron", Critical Factors for Localized Corrosion TI, editcd by P.M. 

Natishan, R.G.Kelly, G.S. Frankcl, and R.C. Newnan, Electr.ochcniicnlSoc., 9S/lS, 24 1, (1 996). 

Beamline XI 1 A 

T. Alcacio, XAFS AnalvsisofLead Sorntion at the MincralIWater Interface, M.S. Thcsis, Univcrsity of Dclawarc, 

(1 997). 

D. Aldrich, Characterization ofthc Solid Phase Rcaction ofTitaniuni with Silicon Gcrnianiuiii Alloys: Intcrfacc 

Reactions. Phase Formation and Stability, Thesis, North Carolina State University, (1995). 

0. Alexeev, M. Shclef, and B.C. Gates, "MgO-supported Platinum-Tungstcn Catalysts Prcparcd from Organo- 

metallic Precursers: Platinum Clusters Isolatcd on Dispersed Tungsten", J. Cntctcrl., 163, 1, (1 996). 

M. Balasubranianian, Studies ofTernarv Doncd Intcnnctallics and Nanostructurcd Materials Usinr X-ray 

Absorotion Spcctrosconv, Thesis, Univcrsity of Connecticut, (1 996). 

B. I. Boyanov, Sunnort and Te~nncrature Effects in Platinum Clusters, Thesis, Illinois lnstitutc of Technology, 

(1 995). 

D.L. Brewe, S.M. Heald, B. Barg, F.C. Brown, K.H. Kim, and E.A. Stcrn, "Capillary X-ray Coniprcssor: Prin- 

ciplevs. Practice, X-ray Microbeam Technology and Applications", editcd by W. Yun, SPJE. 2516, 197, (1 996). 

J.-R. Chang, J.-F. Lee, S.D. Lin, and A.S. Lin, "Carbon-Supportcd Platinum Catalyst Elcctrodc: Characterization 

by Transmission Electron Microscopy, X-ray Absorption Spectroscopy, and Elcctrochcmical Hal f-Ccll Mcasurcment 

on a Phosphoric Acid Fuel Cell", J. ofPIijx Cl~cni., 99, 14798, (1995). 

Y. Dao, Growth and Characterization of (Ti,-y Zrl)Si, Thin Films on Silicon, Thcsis, North Carolina Statc 

- - 

University, (1 995).

M.J. Eick, Dissolution Kinetics of Lunar Simulants and Sorption of Oxyanions andNickel on Secondary Weath- 

ering Products, Ph.D. Dissertation, University of Delaware, (1 995). 

M. Endregard, D.G. Nicholson, M. Stocker, and G. Lamble, "Cobalticenium Ions Adsorbed on Large-Pore 

Alumininophosphate VPI-5 Studied by XAS, 13C Solid-state NMR and FT IR", J. Mat. Chem., 5,485, (1995). 

S.E. Fendorf, Sorption and Oxidation Mechanisms of Hydrolyzable Metal Ions on Oxide Minerals, Ph.D. 

Dissertation, University of Delaware, (1 992). 

S.E. Fendorf, M.J. Eick, P.R. Grossl andD.L. Sparks, "Arsenate and Chromate Retention Mechanisms on 

Goethite. 1. Surface Structure", Environ. Sci. Technol., 31,3 15-320, (1 997). 

S.E. Fendorf, and D.L. Sparks,. "Application of Surface Spectroscopies and Microscopies to Elucidate Sorption 

Mechanisms on Oxide Surfaces", Trans. oflnt. Soc. SoilSci., 3a, 182-199, (1994). 

S.E. Fendorf, and D.L. Sparks, "Mechanisms of Chromium(II1) Sorption on Silica: 11. Effects of Reaction 

Conditions", Environ. Sci. Technol., 28,290-297, (1994). 

S.E. Fendorf, D.L. Sparks, and M. Fendorf, "Mechanisms of Aluminum Sorption on Birnessite: Influences on 

Chromium Oxidation", Trans. oflnt. Soc. Soil Sci., 3a, 129-145, (1994). 

S.E. Fendorf, M.J. Eick, P.R. Grossl, and D.L. Sparks, "Arsenate and Chromate Retention Mechanisms on 

Geothite: Surface Structure", Environ. Sci. Tech., 31,3 15, (1997). 

A. Frenkel, B. Barg, S.M. Heald, F.C. Brown, K.H. Kim, and E.A. Stern, "Optimization of Monochromatic 

Crystal Bending Designs Using Computer Solutions", 67,9, (1 996). 

A.I. Frenkel, E.A. Stern, and F. A. Chudnovsky, "Metal-Insulator Transition and Local Structure of V,03", J. 

Phys. IV France 7 (Proceedings of the 9th International Conference on X-Ray Absorption Fine Structure), pp. 

C2-1061-C2- 1063, (1 997). 

A.I. Frenkel, E.A. Stem, and F.A. Chudnovsky, "Local Structure Changes in V, 0, Below and Above the Metal- 

Insulator Transition", SolidState Comm., 102,637, (1997). 

A.I. Frenkel, E.A. Stern, A. Rubshtein, A. Voronel, and Y. Rosenberg, "Local Structural Distortions in Quenched 

Au-Cu Alloys", J. Phvs. IV France 7, Proceedings of the 9th International Conference on X-Rav Absorption Fine 

Structure, pp. C2-1005-C2-1006, (1997). 

A.I. Frenkel, E.A. Stern, A. Voronel, and S.M. Heald, "Lattice Strains in DisorderedMixed Salts", SolidState 

Commun., 99,67, (1996). 

A.I. Frenkel, E.A. Stern, A. Voronel, A. Rubshtein, Y. Ben-Ezra, andV. Fleurov, "Redistribution ofLa-A1 

Nearest-Neighbor Distances in the Metallic Glass Al,,, Lao,,," Phys. Rev., B54,884, (1996). 

J.L. Fulton, D.M. Pfund, S.L. Wallen, M. Newville, and E.A. Stem, "Rubidium Ion Hydration in Ambient and 

Supercritical Water7',J. of Chem. Phys., 10516,2161, (1996). 

P.R. Grossl, M.J. Eick, S. Goldberg, C.C. Ainsworth, and D.L. Sparks, "Arsenate and Chromate Retention 

Mechanisms on Goethite. 2. Kinetic Evaluation using a Pressure-jump Relaxation Technique", Environ. Sci. 

Technol., 31,321-326, (1997).

A. Hamid Muhamnied Fasihuddin, L-edrre X-ray Absorption Study of B-phase Niid,,,,,:_\ and ofthc effects of 

Substitutional Fe Atoms on its Local Electronic Structure, Thesis, University ofConnecticut, (1 997). 

D. Haskel, M. Qian, E.A. Stern, and M. Sarikaya, "Developnicnt ofEXELFS for Nanoscalc Atomic Structure 

Determination", J. Plivs. IV France 7 (Proceedings ofthe 9th International Confcrcncc on X-Ray Absorption 

Fine Structure), pp. C2-557-C2-560 (1997). 

D. Haskel, E.A. Stern, D.G. Hinks, A.W. Mitchell, J.D. Jorgcnson, and J.1. Budnick, "Dopant and Tenipcrature 

Induced Structural Phase Transitions in La,-,SrxCuO,", Plijs. Ru: Lett., 76,439, (1996). 

D. Haskel, and E.A. Stern, "Altered Sr Atomic Environnient in La,-,Sr,CuO,", J. Phys. IV France 7 Procccdinrrs 

of the 9th International Conference on X-Ray Absorption Fine ~kcturc, pp. C2-1 l77-C2-1178, (1997). 

D. Haskel, E.A. Stern, D.G. Hinks, A.W. Mitchell, and J.D. Jorgensen, "Altcrcd Sr Environment in 

La,xSrxCuO,", Plgir. Rev., B56, R52 1, (1 997). 

S.M. Heald, D.L. Brewe, B. Barg, K.H. Kim, F.C. Brown, and E.A. Stern, "Micro-XAS Using Tapered Capillary 

Concentrating Optics", J. Phvs. IV France 7 Proccedinrs of the 9th International Confercncc on X-Ray Absorp- 

tion Fine Structure, pp. C2-297-C2-301, (1 997). 

S.M. Heald, D.L. Brewe, K.H. Kim, F.C. Brown, B. Barg. and E.A. Stern, "Capillary Concentration for Synchro- 

tron Radiation Beamlines", Optics for High Brightness Svnchrotron Radiation Bcanilines #2, edited by Lonny E. 

Berman and John Arthur, SPIE, 2856,36, (1996). 

J. Kropf, XAFS and Refleetivitv Investirations of Solid-Solid Interfaces, P11.D. Dissertation , Notre Dame 

University, (1 997). 

Q. Lu, XAFS Investieations of Structural Properties at Internal Interfaces. P1i.D. Dissertation, Notrc Dame 


Q. Lu, B. A. Bunker, H. Lou, A. J. Kropf, K. M. Keniner, J. K. Furdyna, and G. C. Hua. "X-ray Study of Atomic 

Correlations in ZnCdSeTe Epitaxial Thin Films", Plijx Re\,., B55, 99 10, (1 997). 

A.N. Mansour, and C.A. Melendres, "Chemistry, Structure and Morphology ofNative and Passive Oxide films 

on Aluminum Rich Amorphous Al-Fe-Ce Alloys", Proceedines ofthe Tri-Sen~icc Confercncc on Corrosion, p. 

129, (1994). 

J. McBrecn, X.Q. Yang, and H.S. Lee, "X-Ray Absorption Studies ofNiBr, (PEO), and ErBr,(PEO),, Coni- 

plexes", Mucr-oniol. S'wp. 105, 185 (1 996). 

A. Moen, and D. G. Nicholson, "Reduction of Copper(I1) with Subsequent Disproportionation of Copper(l) 

During the Hydrothern~al Syntheses ofMicroporous Silicoaluniiniuni Phosphates SAPO-5 and -1 1 ", J. Cl~cnt. 

Soc. Faradp Trans., 91,3529, (1 995). 

M. Newville ,Local Therniodynaniic Measurenients of Dilute Binary Alloys usinr XAFS, Thesis, University of 

Washington, (1 995). 

M. Newville, J.L. Fulton, D.M. Pfund, S.L. Wallen, E.A. Stern, and Y. Ma, "XAFS Mcasurcments of Rb-0 

Bonds in Ambient and Supercritical Watcr", J. Phvs. IV France 7 Proceedings of the 9th International Confer- 

ence on X-Ray Absorption Fine Structure, pp. C2- 1007-C2- 1008 (1 997).

1 

I 

~ 

P. A. Northrup, Topaz: Differential Incorporation and Growth Kinetics Controlled by Detailed Surface Stmc- 

ture, State University ofNew York at Stony Brook, Thesis, (1996). 

- 

K.I. Pandya, K.E. Swider, D.A. Corrigan, and W.E. O'Grady, "In Situ Evidence for Quadrivalent Nickel in 

Nickel Battery Electrodes",J. Electrochem. Soc., 143,1601, (1 996). 

M. Qian, M. Sarikaya, and E.A. Stern, "EXELFS (-Data Renormalization", Ultramicroscopy, 68,163, (1 997). 

D.E. Ramaker, H. Sambe, H. Qian, and W.E. O'Grady, "Identification of Resonant, Two Electron, and Inter- 

atomic features in K and L23 NEXAFS Spectra", Physica, B208 & 209,49, (1 995). 

B. Ravel, Ferroelectric Phase Transitions in Oxide Perovskites Studied by XAFS, Thesis, University of Washing- 

ton, (1997). 

B. Ravel, andE.A. Stem, "Temperature and Polarization Dependent XANES Measurements on Single Crystal 

PbTiO,", J. Phys. IV France 7 Proceedings of the 9th International Conference on X-Ray Absorption Fine 

Structure, pp. C2-1223-C2-1224, (1 997). 

M. Sarikaya, M. Qian, andE.A. Stern, "EXELFS Revisited", Micron, 27,449-466, (1996). 

A.M. Scheidegger, and D.L. Sparks, "A Critical Assessment of Sorption-Desorption Mechanisms at the Soil 

Minerallwater Interface", SoilSci., 161,813-83 1, (1996). 

A.M. Scheidegger, and D.L. Sparks, "Kinetics ofthe Formation and the Dissolution ofNickel Surface Precipi- 

tates onPyrophyllite", Chem. Geol., 132,157-164, (1996). 

A.M. Scheidegger, M. Fendorf, andD.L. Sparks, "Mechanisms ofNickel Sorption on Pyrophyllite: Macroscopic 

andMicroscopic Approaches", Soil Sci. Soc. Am. J., 60,1763-1772, (1996). 

A.M. Scheidegger, G.M. Lamble, and D.L. Sparks, "Spectroscopic Evidence for the Formation of Mixed-cation 

Hydroxide Phases upon Metal Sorption on Clays and Aluminum Oxides",J. ColloidInterJ: Sci., 18,118-120, 

(1997). 

N. Sicron, Y. Yacoby, E.A. Stem, and F. Dogan, "XAFS Study ofthe Antiferroelectric Phase Transition in 

PbZrO,", J. Phys. IV France 7 Proceedings of the 9th International Conference on X-Ray Absorption Fine 

Structure, pp. C2-1047-C2-1049, (1997). 

E.A. Stern, "XAFS and Thermal Averaging", J. Phys. IV France 7 Proceedings ofthe 9th International Confer- 

ence on X-Ray Absorption Fine Structure, pp. C2- 137-C2- 140, (1 997). 

E.A. Stem, "Development of XAFS into a Structure Determination Technique", Roentgen Centennial: X-Rays 

inNatura1 and Life Sciences, Edited by A. Haase, G. Landwehr, and E. Umbach, World Scientific, Singapore, pp. 

323-340, (1 997). 

E.A. Stem, andY. Yacoby, "Structural Disorder in Perovskite Ferroelectric Crystals As Revealed by XAFSV,J. 

Phys. & Chem. ofSolids, 57,1449-1455, (1996). 

R.V. Vedrinskii, V.L. Kraizman, A.A. Novakovich, Ph.V. Demekhin, S.V. Urazhdin, B. Ravel, and E. A. Stern, 

"Pre-Edge Fine Structure (PEFS) of the K-XAS for the 3d Atoms in Compounds: ANew Tool for Quantitative 

Atomic Structure Determination" J. Phys. IV France 7 Proceedings of the 9th International Conference on X- 

Rav Absorption Fine Structure, pp. C2- lO?'-C2- 1 10, (1 997).

F. Wang, B. Ravel, Y. Yacoby, E.A. Stern, and R. Ingalls, "The Effect of Hydrostatic Prcssurc on the Local 

Structure of K,-+NaxTaO, and Kta,-ANbx0,'7, J. Phvs. IV France 7 Procecdings of thc 9th International Conference 

on X-Ray Absorption Fine Structure, pp. C2-1225-C2-1226, (1 997). 

K. Xia, W.F. Bleam and P.A. Helmke, "Studies ofthc Nature of Binding Sites of First-row Transition Elcmcnts 

Bound to Aquatic and Soil Humic Substances using X-ray Absorption Spectroscopy", Geochinl. Cosniochi~ii. Actcr, 

61,2223-2225, (1997). 

K. Xia, W.F. Bleam, and P.A. Helmke, "Studies ofthe Nature of Cu2' and Pb2' Binding Sites in Soil Humic 

Substances using X-ray Absorption Spectroscopy", Geochini. Cosniochini. Acta, 61722 1 1-222 1, (1 997). 

K. Xia, A. Mehadi, R.W. Taylor, and W.F. Blcam, "X-ray Absorption and Electron Paramagnetic Resonance 

Studies ofCu(I1) Sorbed to Silica: Surface-induced Precipitation at low Surface Covcragcs",.?. Colloidlritc~~/i~c.c 

Sci., 185,252-257, (1997). 

Y. Yacoby, S.M. Heald, and E.A. Stern, "Local Oxygen Octahedra Rotations in Ba,-\ KA BiO, and BaBiO,", Solid 

State Conrmun., lOl,8Ol, (1997). 

Y. Yacoby, S.M. Heald, and E.A. Stern, "Local Oxygen Octahedra Rotations in Ba,-\K\BiO,", 1. Phys. IV France 

7 Proceedings ofthe 9th International Conference on X-Rav Absorption Fine Structurc, pp. C2- I08 1 -C2- 1083, 

(I 997). 

Y. Yacoby, and E.A. Stern, "Structural Disorder in Crystals Undergoing Displacive Typc Structural Phasc Transitions 

As Revealed by XAFS", Coriz~~~erits of Cold. Mar. Plijs., 18, 1, (1 996). 

Y. Zhang , XAFS Research on Biological Systems, M.S., University of Washington, ( 1995). 

A. Zhao, Structurally Well-Defined Supported Iridium cluster Catalvsts: Svnthcsis, Characterization, and 

Catalysis, University ofDelaware, Thesis, (1 996). 

Beamline X12B 

M.A. Canady, S.B. Larson, J. Day, and A. McPherson, "Crystal Structurc ofTurnip Yellow Mosaic Virus", Not. 

Struc. Biol., 31 9,771, (1996). 

T.R. Gamble, F.F. Vajdos, S. Yoo, D.K. Worthylake, M. Houseweart, W.I. Sundquist, and C.P. Hill, "Crystal 

Structure of Human Cyclophilin A Bound to the Amino-terminal Domain of HIV- 1 Capsid", Cell, 87, 1285, 

(1 996). 

L.J. Harris, S.B. Larson, K.W. Hasel, and A. McPherson, "Refined Structurc ofan Intact IgG2a Monoclonal 

Antibody", Biocheniist~y, 3617, 158 1, (1 997). 

S. Koszelak, J.D. Ng, J. Day,T.-P. KO, A. Greenwood, and A. McPherson, "Thc Crystallographic 

Structure ofthe Subtilisin Protease from Penicillium Cyclopium", Biochcnii.vtq,, 36,6597, (1 997). 

H. Lin, J.J. Dunn, B.J. Luft, and C.L. Lawson, "Crystal Structure of Lyme Discase Antigcn Outcr Surface 

Protein A Complexed with an Fab", Biochemistry,, 94,3584, ( 1997). 

A.J. Malkin, Y.G. Kuznetsov, and A. McPherson, "Defect Structurc of Macroniolccular Crystals",./. Stri~c. 

Biol., 

117, 124, (1996).

A.J. Quantock, N.J. Fullwood, EJ-MA. Thonar, S.R. Waltman, M.S. Capel, M. Ito, S.M. Verity, and D.J. 

Schanzlin, "Macular Corneal Dystrophy Type 11: Multiple Studies on a Cornea with Low Levels of Sulphated 

Keratan Sulphate", Eye, 11,57, (1997). 

A. J. Quantock, S.M. Verity, and D. J. Schanzlin, "Organization of Collagen in the Lyophilized Cornea",J. 

Refract. Surg., 13,169, (1997). 

M.O. Skidmore, andM.R. Sawaya, et al., "Crystallization ofthe A Alpha Subunit ofprotein Phospahtase 2A", 

Protein Science, 5,1198, (1996). 

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M.K. Durbin, A. Malik, A.G. Richter, R. Ghaskadvi, T. Gog, and P. Dutta. "Transitions to a new Chiral Phase 

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J. Braun, J.P. Toennies, and G. White, "A SPALEED Stnlctural Study of Cesium Adsorption on Stcppcd Copper 

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H. Hua, S. Mirov, and Y. K. Vohra, "High-Pressure and High-Teniperature Studies on Oxide Garnets", Pl~jts. 

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M.B. Kruger, and C. Meade, "High Pressure Structural Study ofGel4", Plljx. Re),., B55, I, (1 997). 

M.B. Kruger, J.H. Nguyen, W. Caldwell, and R. Jeanloz, "Equation of State of MgAI,O, Spinel to 65 GPa", 

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M.B. Kruger, J.H. Nguyen, Y.M. Li, W. Caldwell, M.H. Manghnani, and R. Jeanloz, "Equation of State ofa- 

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Y.M. Li, M.B. Kruger, J.H. Nguyen, W.A. Caldwell, and R. Jealoz, "High Pressure X-ray Diffraction Study ofp- 

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P. Loubeyre, R. LeToullec, D. Hauserniann, M. Hanfland. R.J. Hemley, H.K. Mao, and L.W. Finger, "X-ray 

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H.K. Mao, and R.J. Hemley, "Solid Hydrogen at Ultrahigh Prcssurcs", Hich Prcssure Science & Technologv- 

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H.K. Mao, J. Shu, Y. Fei, H. Hu, and R.J. Hemley, "The Wiistite Enignia", Pl~jx E(rr.th Plrrrtcf. Irltcv.., 96, 135, 

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J.H. Nguyen, M.B. Kruger, and R. Jealoz, "Evidence for 'Partial' (Sublattice Amorphization in Co(O1 I),", Pl~j~,v. 

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S.K. Saxena, L.S. Dubrovinsky,C.S. Yoo,J. Akella, A.J. Campbell, H.K. Mao, and R.J. Hemley, "Detecting 

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S.K. Saxena, L.S. Dubrovinsky, and P. Haggkvist, "X-ray Evidence forthe p-iron at High Temperature and High 

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S.K. Saxena, L.S. Dubrovinsky, P. Lazor, Y. Cercnius, P. Haggkvist, M. Hanfland, and J.Z. Ilu, "Stability of 

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W.L. Vos, L.W. Finger, R.J. Hcmley, and H.K. Mao, "Pressure Dependcncc of Hydrogen Bonding in a Novel 

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C.S. Yoo, J. Akella, H. Cynn, and M. Nicol, "Direct Elementary Rcactions of Boron 

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C.S.Yoo, P. Soderlind, J. Moriarty, and A. Campbell, "Dhcp as a Possible new &'-Phase ofIron at High Pressures 

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Beamline X18A 

J. Anderson, Atomic Short-Range Order Determination in Au-25at.%Fe and Ni-12.5at.%Si: A Svnchrotron X- 

ray Diffuse Scattering Study, Ph.D., LTV Steel, Cleveland, OH., (1996). 

T.E. Burns, Asymmetric Adsorbate and Substrate Interactions in Physisorbed Systems: Nitrogen on Graphite and 

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J. R. Buschert, Time Resolved X-Ray Diffraction Studies of Laser Annealing and Photostriction in Silicon, Ph.D., 

Faculty Goshen College, (1 989). 

M.A. Castro, The Pair-Breaking Problem in High Temperature Superconductors: A Study of Magnetic and 

Nonisovalent Impurities in Yttrium Barium Copper Oxide, Ph.D., Purdue University, (1993). 

P. Dai, Svnchrotron X-Ray Diffraction Study of Structure and Growth of Adsorbed Layers, Ph.D, Oak Ridge 

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R. Eisenhower, Multiple Bragg Scattering in Decagonal 0-uasicrystals, Ph.D., NSLS, Brookhaven National 

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G.C. Follis, A Novel Theoretical Technique for Quantitative Analysis of X-Rav Diffraction Data, Ph.D., Purdue 


R. Goldman, Structural and Electronic Properties of Lattice-Matched Compound Semiconductor 

Heterostructures, Ph.D., University of Michigan, (1 995). 

R. S. Goldman, K. L. Kavanagh, H. H. Wieder, V. M. Robbins, S. N. Ehrlich, and R.M. Feenstra, "Correlation 

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R. S. Goldman, K. L. Kavanagh, H. H. Wieder, and S. N. Ehrlich, "Modulation-Doped InGaAsIInAlAs 

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S.A. Hoffman, Testing the Response of High Temperature Superconductors to the Presence of Spins: Nickel, 

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K. Hongladarom, Molecular Orientation and Rheolog of Liquid Crystalline Polymers under Shear Flow, Ph.D., 

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J.M. Honig, S.N. Ehrlich, T.P. Hogan, C.R. Kannewurf, G.L. Liedl, T.F. Rosenbaum, J. Spalek, P. 

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K. Mahalingam, Precipitation Behavior of 6' (AIILi) in a Binanr Alumnium Lithium Alloy, Ph.D., Staff Wright 

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P. Miller, and K. J. Bowman, "The Relation of Contact and Toughness in Textured Silicon Nitridc to Prcfcrrcd 

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J. C. Newton, and H. Taub, "Neutron Diffraction Investigation of the S, Monolayer Phase of Ethane 

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E. Smela, The Effect of Substrate To~olow on Smectic Liouid Cwstal Alifnment: A Hi$ Resolution X-ray 

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N. Takesue, Thermal Diffuse scatter in^ and Inpurity Effect on the Para-To-Ferroclectric Transitions of PbTiOl 

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V. M. Ugaz, D. K. Cinader, Jr. and W. R. Burghardt, "Origins of Region I Shear Thinning in Model 1,yotropic 

Liquid Crystalline Polymers", M~rromolec~~les, 30, 1527, (1 997). 

C. Venkatraman, Structural Characterization and Resistivit~r Variation of Lanthanum Nickclares, M.S., Ad- 

vanced Refractories Technology, Buffalo, NY, (1 990), 

C. Venkatraman, Texture Development in YBCO Films Synthesized from Mctallo-Orranic Precursors, Ph.D., 

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S.-K. Wang, Diffraction St~~dies of the Multilaver Structure Sim~le Physisorbed Films, Ph.D, Sclf-employed, 

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Z. Wu, Diffraction Studies of the Structure and Growth of Films Adsorbed on the Ad1 11) Surfacc, Ph.D., 

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Z. Wu, B.Matthies, K. W. Henvig, H. Taub, and S. N. Ehrlich ,"Quasiepitaxial Growth of n-Butane on a 

Ag(l11) Surface", Bull. Anz. Phys. Sor., 42, 309, (1997). 

Y. Zhang, X-Rav Diffraction St~~dies of Al-Pd-Mn Quasicn;stal. Structural and Thermal Properties, Ph.D., 

Qualcom~ii Inc., San Diego, California, (1 997). 

Beamline X18B 

C.J. Dodge, and A.J. Francis, "Biotransfonnation ofBinary and Ternary Citric Acid Coniplcxcs of Iron and 

Uranium", Environ. Sci. Techriol., 31,3062, (1 997).

C.J. Dodge, A.J. Francis, and C.R. Clayton, "X-ray Spectroscopic Studies ofuranium Transformations in 

Microbial Cultures", In Synchrotron Radiation Techniques in Industrial, Chemical. and Materials Science, 

Edited by L.J. Terminello, K.L. D'Amico, and D.K. Shuh, Plenum Publishing Co., pp. 159-168, (1996). 

E.J. Doskocil, S.V. Bordawekar, and R.J. Davis, "Alkali-Support Interactions on Rubidium Base Catalysts 

Determined by XANES, EXAFS, C02 Adsorption, and IR Spectroscopy",J. Catal., 169,327-337, (1997). 

X. Feng, G. E. Fryxell, L.-Q. Wang, A. Y. Kim, J. Liu, andK. M. Kemner, "Functionalized Monolayers on 

Ordered Mesoporous Supports (SAMMS)", Science, 276,923, (1997). 

C. C. Freyhardt, R. F. Lobo, S. Khodabandeh, J. E. Lewis, Jr., M. Tsapatsis, M. Yoshikawa, M. A. Camblor, M. 

Pan, M.M. Helmkamp, S. I. Zones, andM. E. Davis, "VPI-8: A High-Silica Molecular Sieve with aNovel 

"Pinwheel" Building Unit and Its Implications for the Synthesis of Extra-Large Pore Molecular Sieves", J. Am. 

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G. Larson, E. Lotero, L.M. Petkovic, and D.S. Shobe, "Alcohol Dehydration Reactions over Tungstated Zirconia 

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D. E. Resasco, W. E. Alvarez, A. Ali and C. J. Loughran, "Selective Reduction of NOx with Methane on 

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pp. 59-74, (1996). 

Beamline X19A 

K. Chae, Y. Lee, C. Whang, Y. Jeon, B. Choi, and M. Croft, "Charge Redistribution in Ion-Beam-Mixed Pd-Ag 

Alloys", Nucl. Instrum. and Meths. In Phys. Rex, B117,123, (1996). 

M. Croft, D. Sills, M. Greenblatt, C. Lee, S.-W. Cheong, K.V. Ramanujachary, and D. Tran, "Systematic Mn-d 

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E. Fujita, L.R. Furenlid, and M.W. Renner, "Direct XANES Evidence for Charge Transfer in Co - CO, Com- 

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J. L. Fulton, D.M. Pfund, and Y. Ma, "A Diamond-Window XAFS Cell for Studies of High-Temperature, High- 

Pressure, Aqueous Solutions", Rev. Sci Instrum., 67,l-5, CD-ROM Issue, (1996). 

J. L. Fulton, D. M. Pfund, S. L. Wallen, M. Newville, E. A. Stem, and Y. Ma, "Rubidium Ion Hydration in 

Ambient and Supercritical Water",J. Chem. Phys., 105,2 16 1, (1996). 

L.R. Furenlid, A. Mayer, and J.P. Kirkland, "NSLS-DAC: A Beamline Control and Data Acquisition Package", J. 

de Phys., C217,335, (1997). 

F. E. Huggins, and G. P. Huffman, "Application ofXAFS Spectroscopyto Coal Geochemistry", - 

Mineral Spectroscopy: A Tribute to Roger G. Bums, edited by M. D. Dyar, C. A. McCammon, and M. W. 

Schaefer, The Geochem. Soc., 5,133, (1996). 

F. E. Huggins, and G. P. Huffman, "Modes of Occurrence of Trace Elements in Coal from XAFS Spectroscopy", 

Int. J. Coal Geol., 32,3 1, (1996). 

F.E. Huggins, G.P. Huffinan, G.E. Dunham, and C.L. Senior, "XAFS Examination of Mercury Capture on 

Three Activated Carbons", ACSDiv. Fuel Chem., 4214,118, (1997).

F.E. Huggins, S. Srikantapura, B.K. Parckh, L. Blanchard, and J.D. Robertson, "XANES Spectroscopic Characterization 

of Selected Elements in Deep-Cleaned Fractions of Kentucky#9 Coal", Eiicig-& fi~cls, 1 1,69 1, 

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F. E. Huggins, J. Zhao, N. Shah, F. Lu, G. P. Huffnian, L. E. Bool, 111, and C. L. Senior, "Investigation ofthc 

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ins, ICCS '97. 9fiInternational Confercncc on Coal Science, edited by A. Ziegler, K.H. van Hcck, J. Klcin, and 

W. Wanzl, P& WDiuckaiid Vei-lag, Essen, 1,38 1, (1 997). 

G. Liang, H. Xi, E. Roberts, T. Binford, K. Mochizuki, J. Markcrt, and M. Croft, "Lattice, Cc-L, Valence, 

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B. J. Palmer, D. M. Pfund, and J. L. Fulton, "Direct Modeling ofXAFS Spectra from Molecular Dynamics 

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J. E. Penner-Hahn, P. J. Riggs-Gelasco, E. Yu, P. DcMarois, and C. F. Yocum, "Structural Characterization of 

the Manganese Cluster in the Photosynthetic Oxygen Evolving Complex Using X-Ray Absorption Spectroscopy", 

Photosvnthesis: from Lirrht to Biosphere. Vol. 11, edited by P. Mathis, Klu\wr Acadcniic Publishers, Dordrccht, 

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A. Pullia, L. Furcnlid, H.W. Krancr, G. Bertuccio, P.J. Pictraski, and D.P. Siddons, "High-Resolution Multi- 

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M.W. Renner, L.R. Furcnlid, K.M. Barkigia, and J. Fajer, "XAFS and Crystallographic Stildies ofNi(l1) Porphy- 

rins in Single Crystals and Solution", J. de Phj:~., C217,66 1, (1 997). 

P.J. Riggs-Gelasco, R. Mei, C.F. Yocuni, and J.E. Pcnner-Hahn, "Reduced Derivatives ofthc Mn Cluster in the 

Oxygen Evolving Complex of Photosysteni 11: An EXAFS Study", J. Aiu. C~CIII. SOC., 118,2387, (1 996). 

P. Schmuki, S. Virtanen, H. S. Isaacs, A. J. Davenport, H. Bohni, and T. Stenberg, "Iii situ XANES Studics on 

the Electrochemical Behavior ofThin (Fc,Cr)-Oxide Films used as Models for Passive Films", Surfacc Oxide 

Films, edited by J. Bardwell, The Electi-ochei~iicnISoc., 96118,234, (1 996). 

A. Siniopoulos, D. Devlin, A. Kostis, A. Jankowski, M. Croft, and T. Tsakalakos, "Structure and Enhanced 

Magnetization in Fe/Pt Multilaycrs", Ph~~s. Rev., B54,993 1, (1996). 

T.L. Stemmler, T.M. Sossong Jr., J.I. Goldstcin, D.E. Ash, T.E. Elgren, D.M. Kurtz Jr., and J.E. Pcnncr-Hahn, 

"EXAFS Comparison ofthe Dimangancse Core Structurcs of Mn Catalase, Arginasc and Mn-Substitutcd Ribo- 

nucleotide Reductasc and Hemerythrin", Biochcniisti:1., 36,9847, (1 997). 

David L. Tierney, XAS Characterization ofBacterial Superoxide Distiiutase and NMR Characterization of 

Substrate Binding in Phthalate Dioxv~enase, Ph.D. Thesis, University of Michgian, (1996). 

S. L. Wallen, D. M. Pfund, J. L. Fulton, C. R. Yonker, M. Newville, and Y. Ma, "A High-Pressure, Capillary 

XAFS Cell for Studies of Liquids and Supercritical Fluid Solutions", Rcl: Sci li~.st~.lrni., 67,2843, (1 996). 

T. Yaniamota, M. Croft, R. Shull, and H. Hahn, "Phase Identification of a Superparaniagnctic Iron-OxiddSilvcr 

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Beamline X19C 

H. Chung, W. Si, M. Dudley, A. Anselmo, D.F. Bliss, A. Maniatty, H. Zhang, and V. Prasad, "Characterization 

of Structural Defects in MLEK Grown InP Single Crystals using Synchrotron White Beam X-ray Topography", J. 

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M. Dudley, W. Si, S. Wang, C.H. Carter, Jr., R. Glass, andV.F. Tsvetkov, "Quantitative Analysis of Screw 

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X. Hu, I. Baker, and M. Dudley, "Temperature Dependence of Dislocations in Notched Ice Crystals", J. Phys. 

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N. Lei, A. Huang, and S.A. Rice, "Structure ofthe Liquid-Vapor Interface of a Sn:Ga Alloyn,J. Chem. Phys., 

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N. Lei, A. Huang, S.A. Rice, and C.J. Grayce, "In-Plane Structure ofthe Liquid-Vapor Interfaces ofDilute 

Bismuth:Gallium Alloys: X-ray Scattering Studiesn,J. Chem. Phy., 105,9615, (1996). 

B.M. Park, S.J. Chung, H.S. Kim, W. Si, and M. Dudley, "Synchrotron White Beam X-ray Topography of 

Ferroelectric Domains in BaTiO, Single Crystal", Phil. Mag., A756 1 1, (1997). 

D.R. Rhiger, S. Sen, J.M. Peterson, H. Chung, and M. Dudley, "Lattice Mismatch Induced Morphological 

Features and Strain in HgCdTe Epilayers on CdZnTe Substrates", J. Elect. Mat., 26,5 15, (1997). 

M.L. Schlossman, "Surfaces and Interfaces ofFluids, Structure of ', Encyclopedia ofAppl. Phys., 20,3 1 1, (1997). 

W. Si, M. Dudley, R. Glass, V. Tsvetkov, and C.H. Carter, Jr., "Hollow-Core Screw Dislocations in 6H-Sic 

Single Crystals: a Test ofFrank's Theory",J. Elect. Mat., 26,128, (1997). 

W. Si, M. Dudley, H.S. Kong, J. Sumakeris, and C.H. Carter, Jr., "Investigations of 3C-Sic Inclusions in 4H- 

Sic Epitaxial Films Grown on 4H-Sic Single Crystal Substrates", J. Elect. Mat., 26,l, (1 997). 

W.M. Vetter, and M. Dudley, "X-ray Topography of a Single Superscrew Dislocation in 6H-Sic", Defects in 

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Beamline X20A 

L.J. Buller, Electrochemical and X-ray Studies ofthe Structure and Dynamics of Deposition of Metal Monolay- 

ers, Thesis, Cornell University, (1 997). 

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Q. Feng, Q.J. Harris, R.J. Birgeneau, and J.P. Hill, "Neutron and X-ray Scattering Studies of Field-cooled 

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A.C. Finnefrock, L.J. Buller, K.L. Ringland, P.D. Ting, H.D. Abruna, and J.D. Brock, "Time-Resolved Measure- 

ments of Overlayer Ordering in Electrodeposition", Mat. Res. Soc. Proc., 451,49, (1997). 

J.P. Hill, Q. Feng, Q.J. Harris, R.J. Birgeneau, A.P. Ramirez, and A. Cassanhoi, "Phase Transition Behavior in 

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P.M. Mooney, "Strain Relaxation and Dislocations in SiGe/Si Structures", Mat. Sci. And Eng., R17,105, (1996).

K.P. Rodbell, V. Svilan, L.M. Gignac, P.W. DeHaven, R.J. Murphy, and T.J. Licata. "Film Crystallographic 

Texture and Substrate Surface Roughness in Layered Aluminum Metallization", Mat. Rcs. Soc. Proc., 428,26 1, 

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F.M. Ross, K.M. Krishnan, N. Thangaraj, R.F.C. Farrow, R.F. Marks, A. Cebollada. S.S.P. Parkin, M.F. Toncy, 

M. Huffinan, C.A. Paz De Araujo, L.D. McMilan, J. Cuchiaro, M.C. Scott, C. Echcr, F. Poncc, M.A. O'Keefe, 

and E.C. Nelson, "Applications of Electron Microscopy in Collaborative Industrial Rcscarch", MRS Bullctiri, 211 

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V. Svilan, K.P. Rodbell, L.A. Clevenger, C. Cabral, Jr., R.A. Roy, C. Lavoie, J. Jordan-Sweet, and J.M.E. Marpcr, 

"CrystallographicTexture of C54 Titanium Disilicide as a Function of Dccp Submicron Structure Geometry", 

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Beamline X20C 

C. Cabral, Jr., L.A. Clevenger, J.M.E. Harper, R.A. Roy, K.L. Saenger, G.L. Miles, and R.W. Mann, "/ti Situ X- 

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C. Cabral, Jr., L.A. Clevenger, R.A. Roy, G.B. Stephenson, C. Lavoie, K.L. Saenger, J. Jordan-Swcct, R. 

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ULSI XI Conference Proceedings. Mat. Res. Soc., p. 439, (1996). 

J.R.A. Carlsson, L.A. Clevenger, L.D. Madsen, L. Hiltman, X.H. Li, J. Jordan-Swcct, C. Lavoie, R.A. Roy, C. 

Cabral, Jr, K.L. Ludwig, G. Morales, K.L. Ludwig, G.B. Stcphcnson, and H.T.G. Hentzcll, "Phase Formation 

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Diffraction Measurcmcnts, and Prcdictcd by a Thcorctical Modcl", Phil. Mag., B75,363, (1 997). 

L.A. Clevenger, C. Cabral, Jr., R.A. Roy, C. Lavoie, J. Jordan-Sweet, S. Brauer, G. Morales, K.F. Ludwig, Jr., and 

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L.A. Clevenger, C. Cabral, Jr., R.A. Roy, C. Lavoie, K.L. Saenger, J. Jordan-Sweet, G. Morales, K.L. Ludwig, Jr., 

and G.B. Stephenson, 'In Situ Analysis of the Formation of Thin TiSi, (< 50 nni) Contacts in Submicron 

CMOS Structures During Rapid Thermal Annealing", Mat. Res. Svmn. Proc., 402,96, (1 996). 

A. Donienicucci, C. Dehm, S. Loh, L.A. Clevenger, C. Dziobkowski, C. Cabral, Jr., C. Lavoie, and J. Jordan- 

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C. Lavoie, C. Cabral, Jr., L.A. Clevenger, J.M.E. Harper, J.L. Jordan-Sweet, K.L. Saenger, and F. Doany, "Light 

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B. Park, "Ordcr Re-equilibration Kinetics within the B, and DO, Phases of Fe,Al", .Jl~ri. ,I. AppI. Plij).~., 35, 

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C- 40

R.F. Saraf, C. Dimitrakopoulos, M.F. Toney, and S.P. Kowalczyk, "Near Surface Structure of Solvent-Free 

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S. Song, M. Yoon, S.G.J. Mochrie, G.B. Stephenson, and S.T. Milner, "Faceting Kinetics of Stepped Si(l13) 

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Beamline X21 

K. Hamalainen, S. Manninen, C.-C. Kao, W. Caliebe, J.B. Hastings, A. Bansil, S. Kaprzyk, and P.M. Platzman, 

"High Resolution Compton Scattering Study of Be", Phys. Rev., B54,5453, (1996). 

Beamline X22A 

R.R. Adzic, J.X. Wang, O.M. Magnussen, and B.M. Ocko, "The Structure of Tl Adlayers on the Pt(ll1) Elec- 

trode Surface: Effects of Solution pH and Bisulfate Coadsorption", J. Phys,. Chem., 100,1472 1, (1 996). 

N.M. Jisrawi, T.R. Thurston, X.O. Yang, S. Mukerjee, J. McBreen, M.L. Daroux, andX.K. Xing, "In Situ 

Investigation of Working Battery Electrodes using Synchrotron X-ray Diffraction", 

Proc. of the 1996 Fall Meeting of the Materials Research Society. Boston. MA. J. ofMat. Res.,451,30 1, (1 997). 

N.M. Jisrawi, H.Wiesmann, M.W. Ruckrnan, T.R. Thurston, G. Reisfeld, B.M. Ocko, and M. Strongin, "In 

Situ X-ray Investigation of Hydrogen Charging in Thin Film Bimetallic Electrodes", J. Mat. Res., 12,2091, 

(1997). 

L.H. Lewis, D.O.Welch, and T. Thurston, "Texture Determinations in Rare-Earth-Based Permanent Magnets", 

Proc. 9fh International Symposium on Magnetic Anisotropy and Coercivity in Rare-Earth Transition Metal 

Alloys, Edited by F.P. Missell, H.R. Rechenberg, V. Villas-Boas, and F.J.G. Landgraf, pp. 278-287, (1996). 

B.M. Ocko, J.X. Wang, and T. Wandlowski, "Bromide Adsorption on Ag(OO1): a Potential Induced Two- 

Dimensional Using OrderJDisorder Transition", Phys. Rev. Lett., 79, 15 1 1, (1 997). 

B.M. Ocko, and T.H. Wandlowski, "Halide Electroadsorption on Single Crystal Surfaces" Proc. ofthe Materials 

Research Society, Electrochemical Synthesis and Modification ofMaterials,Edited by P. Andricacos, J. 

Delplancke, S. Corcoran, and T. Moffat, Mat. Res. Soc. Symp. Proc., 451,55, (1997). 

T.R. Thurston, P. Haldar,Y.L. Wang, M. Suenaga, N.M. Jisrawi, andU. Wildgruber, 

"In Situ Measurements of Texture and Phase Development in (Bi,Pb),Sr,Ca ,Cu,O,,-Ag Tapes", 

J. ofMat. Res., 12, 891, (1997). 

T.H. Wandlowski, 0. Magnussen, B.M. Ocko, S. Wu, and J. Lipkowski, "The Surface Structure ofAu(111) in 

the Presence of Organic Adlayers-a Combined Electrochemical and Surface X-ray Scattering Study", J Electro. 

Chem., 409, 155, (1996). 

Beamline X22B 

P. Bodeker, Effect ofMetallic Cap Layers on the Magnetic Properties of Thin Epitaxial Cr[OOl] Films, Ph.D. 

Thesis, Ruhr-Universitaet Bochum, (1 996). 

P. Bodeker, P. Sonntag, A. Schreyer, J. Borchers, K. Hamacher, H. Kaiser, and H. Zabel, "Effect of Fe Cap 

Layers on the Spin Density Waves in Epitaxial Cr(OO1) Films7',J. AppI. Phys., 81,5247, (1997).

P. Bodeker, P. Sonntag. A. Schreyer, H. Zabel, J. Borchers, K. Haniacher, and H. Kaiser, "Spin Density Waves in 

Epitaxial Fe/Cr Films", Plysica, B234,464, (1 997). 

G.M. Bomniarito, W.J. Foster, P.S. Pershan, and M.L. Schlossman, "A Determination of the Phase Diagram of 

Relaxed Langnluir Monolayers of Behenic Acid", J. Plij-s. Clicni., 105,5265, (1 996). 

A. Doerr, X.Z. Wu, B.M. Ocko, E.B. Sirota, 0. Gang, and M. Deutsch, "Surface Freezing in Mixtures of Molten 

Alkanes and Alcohols", Colls. & Surf A - Plzjachcni. & Eiig. A.sl'cct.q l28/1-3,63, (1 997). 

B.W. Gregory, D. Vaknin, J.D. Gray, B.M. Ocko, P. Stroeve, T.M. Cotton, and W.S. Struve, "Two-Dimen- 

sional Pigment Monolayer Asseniblies for Light Harvesting Applications: Structural Characterization at the Air/ 

water Interface with X-ray Specular Reflectivity and on Solid Substrates by Optical Absorption Spcctroscopy",.J. 

Phys. Chern., BlOl,2006, (1 997). 

V. Kiryukhin, D. Casa, J.P. Hill, B. Keinier, A. Vigliante, Y. Tomioka, and Y. Tokura, "An X-Ray Induced 

Insulator-Metal Transition in a Colossal-Magnetoresistive Manganite", Nrrtwc, 386,8 13, ( 1997). 

V. Kiryukhin, B. Keimer, J.P. Hill, S.M. Coad, and D.M. Paul, "Synchrotron X-Ray Scattering Study of Mag- 

netic Field Induced Transitions in C~,-~(zn,Ni)~Ge 

,", Plijx Re\)., BS4, 7269, (1996). 

O.M. Magnussen, B.M. Ocko, M. Deutsch, M.J. Regan, P.S. Pershan, D. Abernathy, G. Grubel, and J.F. 

Legrand, "Self-Assembly oforganic Filtiis on a Liquid Metal", Notwe, 384,250, (1 996). 

0. M. Magnussen, B. M. Ocko, M. Deutsch, M. J. Regan. P.S. Pershan, L. E. Bernian, D. Abernathy, J. F. 

Legrand, and G. Grubel, "Organic Layers on Liquid Metals: An X-ray Reflectivity Study ofThiols on Mercury", 

Nature, 384, 250, (1 996). 

R. Moaz, S. Matlic, E. DiMasi, B.M. Ocko, and J. Sagiv, "Self-Replicating Amphiphilic Monolayers", Natwc, 

384, 150, (1996). 

B.M. Ocko, X. Z. Wu, E. B. Sirota, S. K. Sinha, 0 . Gang, and M. Deutsch, "Surface Frcczing in Chain Mol- 

ecules: Normal Alkanes", Plij:~. Rev., E55,3 164, (1 997). 

M.J. Regan, O.M. Magnussen, E.H. Kawamoto, B.M. Ocko, N. Maskil, M. Deutsch, S. Lee, K. Penanen, and 

L.E. Berman, "X-ray Studies of Atomic Layering at Liquid Metal Surfaces", J. qf Noii-Ci:~:stcrlliiic~Solic/.v, 207, 

762, (1996). 

M.J. Regan, P.S. Pershan, O.M. Magnussen, B.M. Ocko, M. Deutsch, and L.E. Bernian. "Capillary-wave 

Roughening of Surface-induced Layering in Liquid Gallium", Plijx Re\,. , BS4,9730-9733, (1 996). 

M.J. Regan, P.S. Pershan, O.M. Magnussen, B.M. Ocko, M. Deutsch, and L.E. Bernian, "X-ray Reflectivity 

Studies ofLiquid Metal and Alloy Surfaces", Plij!!:s. Rev., B55, 15874- 15884, (1 997). 

M.J. Regan, H. Tostmann, P.S. Pershan, O.M. Magnussen, E. DiMasi, B.M. Ocko, and M. Deutsch, "X-ray 

Study ofthe Oxidation of Liquid Gallium Surfaces", Plijx Re\.., BSS, 10786- 10790, ( 1997). 

E.B. Sirota, X.Z. Wu, B.M. Ocko, and M. Deutsch, "What Drives the Surface Frcczing in Alkanes ?", Plij:~. Rcw 

Lett., 79, 53 1, (1 997). 

P. Sonntag, Magnetic and Structural Properties ofThin Epitaxial Cr Films, PhD. Thcsis, Ruhr-Universitaet 

Bochurn, (1 996).

P. Sonntag, P. Bodeker, T. Thurston, and H. Zabel, "Charge Density Waves and Strain Waves in Thin Epitaxial 

Cr(OO1) Films on Nb", Phys. Rev., B52,13450, (1995). 

Beamline X22C 

C. Detlefs, A.H.M.Z. Islam, A.I. Goldman, C. Stassis, P.C. Canfield, J.P. Hill, and D. Gibbs, "Determination of 

Magnetic Moment Directions using X-ray Resonant Exchange Scattering", Phys. Rev., B55, R680, (1 997). 

G. Helgesen, Y. Tanaka, J.P. Hill, P. Wochner, D. Gibbs, C.P. Flynn, and M.B. Salamon, "Magnetic and 

Structural Properties ofErbium Films", Phys. Rev., B56,2635, (1 997). 

J.P. Hill, C.-C. Kao, and D.F. McMorrow, "K-edge Resonant X-ray Magnetic Scattering from a Transition 

Metal Oxide: NiO",. Phys. Rev. Rapid Comm., B55, R8662, (1997). 

S.C. Perry, W.J. Nuttall, W.G. Stirling, G.H. Langer, and 0. Vogt, "X-ray Scattering Study of the two Magnetic 

Correlation Lengths in Uranium Antimonide", Phys. Rev., B54, 10782, (1996). 

J.A. Simpson,R.A. Cowley, D.A. Jehan, R.C.C. Ward, M.R. Wells, D.F. McMorrow, K.N. Clausen, T.R. 

Thurston, and D. Gibbs, "Co-Existence of Long- and Short-Range Magnetic Correlations in Holmium-Erbium 

Superlattices", 2. Phys., B101,35, (1996). 

A. Stunault, S. Langridge, C. Vettier, D. Gibbs, andN. Bemhoeft, "Near-Surface Effects at the Antiferromag- 

netic Phase Transition in Uranium Phosphide", Phys. Rev., B55,423, (1997). 


M.R. Antonio, and L. Soderholm, "Implications of the Unusual Redox Behavior Exhibited by the 

Heteroplyanion [EuP,W,O, ,0]12-",J. Alloys and Compds., 250,541, (1997). 

M. R. Antonio, and L. Soderholm, "Redox Behavior of Europium in the Preyssler Heteropolyanion 

[EUP,W,O~,O]~~-", 

J. Cluster Sci., 7,585, (1996). 

M. R. Antonio, L. Soderholm, and A.J.G. Ellison, "Local Environments of Erbiumand Lutetium in Sodium 

Silicate Glasses7',J. Alloys and Compds., 250,536, (1997). 

M. R. Antonio, L. Soderholm, and I. Song, "Design of Spectroelectrochemical Cell for in situ X-ray Absorption 

Fine Structure Measurements of Bulk Solution Species", J. Appl. Electrochem., 27,784, (1 997). 

S.V. Bordawekar, E.J. Doskocil, and R.J. Davis, "Influence of Support Composition on the Structure and 

Reactivity of Strontium Base Catalysts", Catal. Lett., 44,193, (1 997). 

C.E. Bouldin, L. Furenlid, and T. Elam, "MacXAFS: An EXAFS Analysis Package for the Macintosh", Physica, 

B208&209,190, (1995). 

A.C. Carter, C.E. Bouldin, K.M. Kemner, M.I. Bell, J.C. Woicik, and S.A. Majetich, "The Surface Structure of 

Cadmium Selenide Nanocrystallites", Phys. Rev., B55,13822, (1997). 

J.O. Cross, Analysis of Diffraction Anomalous Fine Structure, PhD. Thesis, University of Washington, (1 977). 

J.O. Cross, M. Newville, L.B. Sorensen, H.J. Stragier, C.E. Bouldin, and J.C. Woicik, "Separated Anomalous 

Scattering Amplitudes for the Inequivalent Cu sites in YBa,Cu,O, using DAFS", J. de Phys. IV, 7,745, (1997).

D. Fauteux, A. Massucco, M. van Buren, B. Ouyang, S. G. Grccnbaum, S.Kostov, and M. L. dcnBocr, "A 

Comparative Study of LiMn,O, froniVarious Sources", Mat. Res. Soc. Proc.. 369,59, (1 996). 

M.R. Franklin, Structure and Marnetisni in Co/X. Fe/Si and FeIlFeSi I Multilavers, PhD Thcsis, Michigan Statc 


M.F. Garcia, J.A. Anderson, and G.L. Hallcr, "Alloy Forniation and Stability in Pd-Cu Binictallic Catalystsn,.J. 

Phys. Chen~., 100, 16247, (1 996). 

D.M. Giaquinta, L. Soderholm, S.E. Yuchs, and S.R. Wasscrnian, "The Speciation of Uraniun~ in a Smectite 

Clay: Evidence for Catalyscd Uranyl Reduction", R~diochirtzicu Actn, 76,113, (1 997). 

D.M. Giaquinta, S.E. Yuchs, L. Soderholni, and S.R. Wassernian, "The Structure of Uranium in Surfacc Modi- 

fied Clays", J. Alloys arid Cor&s., 249, 142, (1 997). 

C.J. Gutierrez, R. Selestino, R.A. Mayanovic, and G. Prinz, "Evidencc for Loosc Spins in Epitaxial AI/Fc/AIn,.J. 

Aypl. Phys., 81,5352 (1997). 

V.G. Harris, K.M. Keniner, B.N. Das, J.C. Woicik, P. Crespo, A. Hcrnando, and A. Garcia Escorial, "Mccliani- 

cal-alloying and Lattice Distortions in Ball-milled CuFe", J. dc P1ij.s. IV, 7, 1 15 1, (1 997). 

V.G. Harris, K.M. Kemner, W.T. Elam, B.N. Das, N.C. Koon, J. Kirkland. P. Crcspo, A. Hcrnando, A. Garcia 

Escorial, and J. Woicik, "Ncar-Neighbor Mixing and Bond Dilation in Mechanically-Deformed CuFe", Phyx 

Rev., B54,6249, (1996). 

K. M. Kemncr, W. T. Elam, D. B. Hunter, and P. M. Bertsch, "EXAFS Studies of the Local Environment of Cs 

in CsBr-dibenzo- 18-crown-6 Ethcr Solutions and Powders", J. Plijs. Clzcwi., 100, 1 1698, ( 1996). 

K.M. Kemncr, D.B. Hunter, W.T. Elani, and P.M. Bertsch, "Cesium XAFS Studics of Solution Phasc Cs- 

Ionophore Coniplexation", Synchrotron Radiation Techniques in Industrial, Chcniical and Materials Scicncc, 

Plenum Press, pp. 149-1 58, (I 996). 

K. M. Kemner, Y. U. Idzerda, V. G. Harris, V. Chakarian, W. T. Elani, C. -C. Kao, E. Johnson, Y. C. Feng, D. 

E. Laughlin, C. T. Chen, K. -K. Lec, and J. C. Lodder, "Dircct Obscniation of Cr Magnctic Ordcr in CoCrTa 

and CoCrPt Thin Films", Rupid Conini. J. App. Plijs., 81, 1002, (1 997). 

A.J. Kropf, XAFS and Reflectivity Investigations of Solid-Solid Intcrfaccs in Supcrlatticcs and Thin Filnis. PhD. 

Thesis, University ofNotre Dame, (1 977). 

G. Larsen, E. Lotero, L.M. Petkovic, and D.S. Shobc. "Alcohol Dehydration Reactions ovcr Tungstatcd Zirconia 

Catalysts",./. ofCatuI., 169,67, (1 997). 

Q. Lu, XAFS Investigations of Stluctural Properties at Internal Intcrfaccs, PhD Thcsis, University ofNotrc 

Dame, (1 996). 

Q. Lu, B. A. Bunker, H. Lou, A. J. Kropf, K. M. Keniner, .I. K. Furdyna. and G. C. Hua. "X-ray Study of Atomic 

Correlations in ZnCdSeTe Epitaxial Thin Films", Plijs. Re\,., B55,99 10, (1 997). 

R.A. Mayanovic, Y. Feng, K.W. Groh, Y. Wang. R.E. Gicdd, and M.G. Moss, "Local Structure Surrounding 

Implanted As Ions in Polysulfone Filnis", Mat. Rcs. Soc. Proc., 321, 1 13 (1 994).

R.A. Mayanovic, C. J. Gutierrez, and G. Prinz, "Investigations on Fe Lattice Strain Relaxation in the Al/Fe/Al 

Trilayer", Mat. Res. Soc. Proc., 437,27, (1996). 

P. Menacherry, and M.F. Garcia, "An X-Ray Absorption Spectroscopy Determination of the Morphology of 

Palladium Particles in KL-zeolite", J. Catal., 166,75, (1 997). 

K.E. Miyano, J.C. Woicik, L. H. Robins, C.E. Bouldin, and D.K. Wickenden, "Extended X-ray Absorption Fine 

Structure Study O ~A~~G~,-~N Films", Appl. Phys. Lett., 70,2108, (1997). 

K.E. Miyano, J.C. Woicik, P. Sujatha Devi, and H.D. Gafney, "Cr K edge X-ray Absorption Study of Cr 

Dopants in Mg,SiO, and Ca2Ge0,", App1.Phy.s. Lett., 71,1168, (1997). 

B. Ravel, M. Newville, J.O. Cross, and C.E. Bouldin, "Analysis ofDAFS Fine Structure and Background", 

Physica, B208&209,145, (1 995). 

L. Soderholm, S. Skanthakumar, U. Staub, M. R. Antonio, and C.W. Williams, "The Effect of f-ion Valence on 

Superconductivity in the Series Pb2Sr2RCu30,(R=Ce, Pr, Tb and Am)", J. Alloys and Compds., 250,623, (1997). 

U. Staub, S. Skanthakumar, L. Soderholm, and R. Osborn, "Magnetic Properties of Pb,Sr,PrCu,O,", J. Alloys and 

Compds., 250,58 1, (1997). 

U. Staub, L. Soderholm, S. Skanthakumar, and M. R. Antonio, "Oxidation States of the Unusual Rare Earths 

(R=Ce, Pr, and Tb) in Double Layer High-Tc Superconductors", J. de Phys. IV., 7,1077, (1997). 

U. Staub, L. Soderholm, S. Skanthakumar, S. Rosenkranz, C. Ritter, and W. Kagunja, "Tb Spin Correlations in 

Pb,Sr2Tb,,Ca,Cu30,", Europhys. Lett., 34,447, (1996). 

J. P. Urbach, 0. M. Foller, E. Goering, H. Paulin, M. Klemm, S. Horn, and M.L. denBoer, "Characterization of 

the Metallic and Insulating Phases ofV203 and (V,Cr),O, by NEXAFS", J. de Phys. IV., 7,535, (1997). 

H. Wang, Platinum-Tin Bimetallic Catalvsts Supported on L-Zeolite: Synthesis and Characterization, PhD. 

Thesis, Yale University, (1997). 

S. R. Wasserman, D. M. Giaquinta, S. E. Yuchs, and L.Soderholm, "The Effects of Surface Modification on the 

Speciation of Metal ions Intercalated into Aluminosilicates", Mat. Res. Soc. Proc., 465,473, (1 997). 

S.R. Wasserman, S.E. Yuchs, D. Giaquinta, L. Soderholm, and K. Song, "Nanoscale Encapsulation: The Struc- 

ture of Cations in Hydrophobic Microporous Aluminosilicates", J. de Phys. IV., 7,803, (1997). 

J.C. Woicik, C.E. Bouldin, K.E. Miyano, and C.A. King, "Unit Cell of Strained GeSi", Phys. Rev., B55,15386, 

(1 997). 


W.B. Alexander, P.E. Pehrsson, D. Black, and J.E. Butler, "X-ray Diffraction Analysis of Strain andMosaic 

Structure in (0 1 1)-Oriented Diamond", 111-Nitride Sic and Diamond Materials for Electronic Devices, MRS 

Symp.Proc., 423,305, (1996). 

A.J. Allen, G.G. Long, H.M. Kerch, S. Krueger, G. Skandan, H. Hahn, and J.C. Parker, "Sintering Studies of 

Nanophase Ceramic Oxides using Small-Angle Scattering", Ceramics: Charting the Future, Proc. 8aCIMTEC 

World Ceramics Congress and Forum on New Materials, edited by P. Vincenzini, Advances in Sci and Tech., 3D, 

1755, (1995). 

C-45

G. Beaucage, J.H. Aubert, R.R. Lagasse, D.W. Schaefer, T. Reiker, P. Ehrlich, R.S. Stein, S. Kulkarni, and P. 

Whaley, "Nanostructured Semi-crystalline Polymer Foanis", J. Po!~nier Sci. and Pcd~wicr PIij:v., 3411 7,3063, 

(1996). 

D.B. Eason, Z. Yu, W.C. Boney, J.W. Cook, Jr., J.F. Schctzina, D.R. Black, G. Cantwell, and W.C. Marsch, 

"High-Brightness Light-Emitting Diodes Grown by MBE on ZnSe Substrates", J. Vuc. SX. ~nc/ Twhnol., B1314, 

1566, (1 995). 

G. Fogarty, B. Steincr, M. Cronin-Golomb, U. Laor, M.H. Garrett, J. Martin, and R. Shrin, "Antiparallcl 

Ferroelectric Domains in Photorefractive Barium Titanate and Strontiuini Barium Niobatc Obscrvcd by Migh- 

Resolution X-ray Diffraction Imaging", J. Opt. Soc. Am., B13,2636, (1 996). 

S. Han, G. Rodriquez, A. Taylor, M.A. Plano, M.D. Moyer, M.A. Moreno, L.S. Pan, D.R. Black, H.E. Burdcttc, 

J. Agcrs, and A. Chen, "Correlation ofElectrical Properties with Defects in a Homoepitaxial Chcmical-Vapor- 

Deposited Diamond Film", MRS Synip.Proc, 416,343, (1996). 

X. Hu, F. Liu, I. Baker, and D. Black, "The Effect ofx-radiation on the Plastic Deformation of Ice", Phil. Mug., 

A7315, 1355, (1996). 

J. Ilavsky, A.J. Allen, G.G. Long, H. Herman, and C.C. Berndt, "Characterization ofthc Closed Porosity in 

Plasma-Sprayed Alumina", J. Muter. Rex., 32,3407, (1 997). 

J. Ilavsky, A.J. Allen, G.G. Long, S. Krueger, H. Herman, and C.C. Berndt, "Influence of Spray Angle on the 

Porous Microstructure of Plasma-Sprayed Ceraniic Deposits", J. AI~v.. Cercrni. Soc., 8013,733, ( 1997). 

R.A. Livingston, and A.J. Allen, "Application of Small-Angle Neutron Scattering Method to the Study ofthc 

Durability of Historic Brick and Mortar", Ceramics in Architccturc, Proc. 8!" CIMTEC World Ceramics Con- 

gress and Foruni on New Materials, edited by P. Vincenzini, Monogmphs in Mutcric11.s ulidSocicty, 1,573, ( 1995). 

G.G. Long, A.J. Allen, S. Krueger, J. Thomas, D.L. Johnson, and C.J. Hwang. "Small-Anglc Scattering Studies of 

the Microstructure of Silicon Nitride during Processing", Hi~h-Performance Materials in Encine techno lo^ 

Proc. 8fiCIMTEC World Ceramics Conrrress and Foruni on new Materials, edited by P. Vinccnzini, A(/VNIICCS ill 

Sci.und Tech., 9,129, (1 995). 

B. Olivier, A. Lagasse, D. Schaefer, J. Barnes, and G.G. Long. "Pore Orientation Periodicity in Porous Polynicr 

and Carbon Structures", Mac/-oniolecrrles, 29,86 15, (1 996). 

P. Pehrsson, T. McCormick, B. Alexander, M. Marchywka, D. Black, J. Butler, and S. Prawlcr, "Homoepitaxial 

Mosaic Growth and LiftoffofDianiond Films", Diamond for Electronic Applications. MRS Synip.Proc., 416, 

51, (1996). 

R.Spal, C. Chiang, G. Riley, and C. Christopherson, "Synchrotron Radiation Digital Microradiography of 

Strained High-Temperature Superconductor Conipositc Tapes", Proc. ICCE14 fourth Int'l Conf. On Conil~osite 

-, pp. 935-936, (1997). 

B.L. Steiner, L.E. Levine, M. Brown, and D. Larson, "Residual Disorder in Low-Prcssurc Lo~tl-Tlicr~iial-Gradient 

Liquid-Encapsulated Czochralski Galliuni Arsenide Observed in High-Resolution Synchrotron Diffraction 

Imaging", J. Cryrt. Growth, 169, 1, (1 996). 

L.D. Zhu, J. Zhao, F. Wang, G. Fogarty, P. Lu, S.B. Kang. M. Sinclair, D. Dimos, M. Cronin-Golonib, B. 

Steiner, P.E. Norris, B. Kear, and B. Gallois, "Epitaxial Electro-Optical SBN Films by Singlc Source Plasma 

Enchanced Metaloorganic Chemical Vapor Deposition", AppI. P1ij:s. Lett., 67, 1836, (1 995).

Beamline X23B 

J.D. Ayers, V.G. Harris, J.C. Sprague, and W.T. Elam, "Nucleation ofthe Nanocrystalline Phase in 

Fe73,5CulNb3Si13,5B,", 

J. Appl. Phys., 75,5801, (1994). 

J. D. Ayers, V. G. Harris, J. A. Sprague, and W. T. Elarn, "The Local Atomic Order of Cu and Fe in Heat 

TreatedFe73,,Nb3CulSi,3,5B, Ribbons", IEEE Trans. on Mag., 29,2664, (1993). 

J. D. Ayers, V. G. Harris, J. A. Sprague, W. T. Elam, and H. N. Jones, "A Model for Nucleation of Nanocrystals 

in the Soft Magnetic Alloy Fe,,,,Nb3Cu,Si13,,B,", Proceedings ofthe 3'd International Conference on 

Nanostructured Materials, Edited by M. L. Trudeau, V. Provenzano, R. D. Shull, and J. Y. Ying, Kona, pp. 391- 

396, (1996). 

M.I. Bell, K. H. Kim, and W. T. Elam, "Direct Observation of Disorder in Perovskite-Structure Ferroelectrics", 

Ferroelectrics, 120,103, (1991). 

D. B. Chrisey, G. P. Summers, W. G. Maisch, E. A. Burke, W. T. Elam, H. Herman, J. P. Kirkland, and R.A. 

Neiser, "Catastrophic Loss of Superconductivity in Ion-Irradiated Films of Yba,Cu,O,,", Appl. Phys. Lett., 53, 

1001, (1988). 

J.O. Cross, B.R. Bennett, M.I. Bell, andK.J. Kuhn, "Synthetic Wide Band-Pass X-ray Polarizers", Appl. Phys. 

Lett., 70,224, (1997). 

P.C. Dorsey, V.G. Harris, P. Lubitz, D. Chrisey, andN.C. Koon, "X-ray Absorption Fine Structure Studies of 

(MnxZn,~x)Fe20,Films", Mat. Res. Soc. Syrnv. Proc., 375,33, (1995). 

J. A. Eastman, M. R. Fitzsirnmons, M. Miiller-Stach, G. Wallner, and W. T. Elam, "Characterization of 

Nanocrystalline Pd by X-ray Diffraction and EXAFS", Nanostruct. Muter., 1,47, (1 992). 

A.S. Edelstein, V.G. Harris, L. Kurihara, D.R. Rolison, and F.H. Katz, "Chemical Synthesis and Properties of 

Nanocrystalline Cu,,Co,,", Processing and Properties ofNanocrystalline Materials,edited by C. Suryanarayana, J. 

Singh, and F.H. Froes, Proceedings ofthe Minerals, Metals and Materials Society, pp. 1 1 1-122, (1996). 

A.S. Edelstein, V.G. Harris, D. Rolison, J.H. Perepezko, and D. Smith, "Nanocrystalline Solid Solutions of Cu/ 

Co and Other Novel Nanomaterials", Mat. Res. Soc. Symp. Proc., 457,261, (1997). 

A.S. Edelstein, F.H. Kaatz, V.G. Harris, L. Kurihara, D.R. Rolison, and D.J. Gillespie, "Chemically-Prepared 

CuCo and CuFe Nanoparticles", Clusters and Nanostructured Materials, edited by P. Jena and S.N. Behera, 

Nova Science Pub., Inc., New York, pp. 41-50, (1996). 

W. T. Elam, J. P. Kirkland, R. A. Neiser, E. F Skelton, S. Sampath, and H. Herman, "Plasma Sprayed High Tc 

Superconductors", Adv. Cer. Mat., 2/3B, 41 1, (1987). 

J.L. Feldman, W.T. Elam, A.C. Ehrlich, E.F. Skelton, D.D. Dominguez, D.D.L. Chung, and F.W. Lytle, 

"Polarized X-Ray Absorption Studies of Graphite Intercalated-Bromide Compounds", Phys. Rev., B33,796 1, 

(1986). 

C.J. Gutierrez, V.G. Harris, J.J. Krebs, W.T. Elam, and G.A. Prinz, "Magnetic and Structural Characteristics of 

Epitaxial FexCo,-x Alloy Films onZnSe(OOl)",J. Appl. Phys., 73,6763, (1993). 

C.J. Gutierrez, G.A. Prinz, J.J. Krebs, M.E. Filipkowski, V.G. Harris, and W.T. Elam, "Magnetic and Structural 

Studies ofEpitaxial(001) Fe and (001) FexCo,-x Alloy Film Structures", J. Mag. and Mag. Mat., 126,232, (1 993).

V.G. Harris, "A Spinning-Stage, Total-Electron-Yield Detector forthe Elimination of Diffraction Peaks in X-ray 

Absorption Spectra", Rev. Sci. /ristr.uw., 6811,23, (1 997). 

V.G. Harris, K.D. Aylesworth, B.N. Das, W.T. Elam, and N.C. Koon, "Determination of Structural Anisotropy 

in Amorphous Tb-Fe Alloy Films", IEEE Tr.ans. on Mcrgrr., 28,2955, (1 992). 

V.G. Harris, K.D. Aylesworth, W.T. Elam, N.C. Koon, R. Coehoorn, and W. Hoving, "Evolution of Structure 

in Fe Layer Thickness in Low-Dimensional Fe/Tb Multilayercd Films", Mat. Rcs. Soc. Symp. Proc., 238,635, 

(I 992). 

V.G. Harris, K.D. Aylesworth, K.H. Kim, W.T. Elam, and N.C. Koon, "EXAFS Studies of IBS Amorphous Fe- 

Tb Alloy Films", J. Appl. Pliys., 70,631 1, (1991). 

V. G. Harris, B. N. Das, M. Rubenstein, J. L. Goldberg, W. T. Elani, and N. C. Koon, "Structural Evolution 

and Magnetoresistance Properties of Heat Treated Cu,,,Co,,Fe, Ribbons", IEEE Tr.arls. or1 Mug., 29,26 16, 

(I 993). 

V.G. Harris and W.T. Elani, "A Miniature Total Electron Yield Detector for Measurcmcnt ofx-ray Absorption 

Spectra", Rev. Sci. Iristrunl., 6815, 1972, (1 997). 

V.G. Harris, W. T. Elani, and N. C. Koon, "Correlation of Magnetic and Structural Anisotropy in Amorphous 

Tb-Fe Films", J. Magri. Soc. &I., 17,267, (1 993). 

V.G. Harris, W.T. Elani, and N.C. Koon, "Structural Origins of Perpendicular Magnetic Anisotropy in Amor- 

phous non-S-state Rare Earth - Transition Metal Alloy Films", High Density Digital Recording, Edited by K.H.J. 

Buschow, G.J. Long and F. Grandjean, Appl Sci., 229,483-5 17, (1993). 

V.G. Harris, K.M. Keniner, W.T. Elani, B.N. Das, N.C. Koon, J. Kirkland, P. Crespo, A. Hernando, A. Garcia 

Escorial, and .I. Woicik, "Near-neighbor Mixingand Bond Dilation in Mechanically-Dcforn~ed CuFc", Pl1j:s. 

Rev., B54,6249, (1 996). 

V.G. Harris, N.C. Koon, C.M. Williams, Q. Zhang, and M. Abe, "Cation Distributions in Spinel Ferrites 

Observed via EXAFS Measurenients",.J. Appl. Phj:~., 7918,456 1, (1 996). 

V.G. Harris, N.C. Koon, C.M. Williams, Q. Zhang, M. Abe, and J. Kirkland, "Cation Distributions in Spinel 

Ferrites via EXAFS", AppI. Plijjs. Lett., 6811 5,2082, (1 996). 

V.G. Harris, N.C. Koon, C.M. Williams, Q. Zhang. M. Abe, J.P. Kirkland, and D.A. McKeown, "Direct 

Measurement of Octahedral and Tetrahedral Site Environnients in NiZn-Ferrites", IEEE Tr.~n.s. or1 Mrrgr~., 3116, 

3473, (1 995). 

V.G. Harris, S.A. Oliver, J.D. Ayers, B.N. Das, and N.C. Koon, "Crystallization ofTliin Amorphous Fe-B Films 

Studied via Empirical EXAFS Modeling", Appl PI1j:s. Lett., 68115,2073, (1 996). 

V.G. Harris, S.A. Oliver, J.D. Ayers, B.N. Das, and N.C. Koon, "Quantitative Crystallization Studies of Thin 

Amorphous Fe,,,B,,, Films via Enipirical Modeling of EXAFS Data", Mat. Res. Soc. Syiip. Proc., 375,9, (1 995). 

V.G. Harris, S.A. Oliver, K.H. Kim, W.T. Elam, R. Culbertson, W.B. Nowak, and C. Vittoria, "Magnetic arid 

Structural Investigation ofHeat-Treated ion Beam Sputtered Amorphous Co,,Fe,,B,,Si, Films", IEEE Trwnxon 

Magn., 26, 1459, (1990).

V.G. Harris, C.M. Williams, Q. Zhang, and M. Abe, "Multiple-Scattering Extended X-ray Absorption Fine 

Structure Analysis of Spinel Ferrites", Coll. Cl, Supp. auJ. de Phys., 7,215 (1997). 

H.A. Hoff, G.L. Waytena, J.W. Glesener, V.G. Harris, and D.P. Pappas, "Critical Thickness of Single Crystal 

fcc-Fe on Diamond", Surj Sci., 326,252, (1995). 

J.S. Honvitz, P.C. Dorsey, N.C. Koon, M. Rubinstein, J.M. Byers, D.J. Gillespie, M.S. Osofsky, V.G. Harris, 

K.S. Grabowski, D.L. Knies, E.P. Donovan, and D.B. Chrisey, "The Effect of Oxygen Pressure and Temperature 

on the Structure and Properties of Pulsed Laser Deposited LaxCal-xMnod Films", SPIE, 2703,526, (1996). 

J.S. Honvitz, P.C. Dorsey, N.C. Koon, M. Rubinstein, J.M. Byers, D.J. Gillespie, M.S. Osofsky, V.G. Harris, 

K.S. Grabowski, D.L. Knies, E.P. Donovan, and D.B. Chrisey, "The Effect of Oxygen Pressure on the Structure 

and Properties of Pulsed Laser Deposited LaxC ,-xMnod Films", Mat. Res. Soc. Symp. Proc., 401,525, (1996). 

F.H. Kaatz, V.G. Harris, L. Kurihara, D.R. Rolison, and A.S. Edelstein, "Slow Oxidation of Cu-Co 

Nanocrystals", Appl. Phys. Lett., 6715,3807, (1995). 

K. M. Kemner, W. T. Elam, V. G. Harris, Y. U. Idzerda, and J. A. Wolf, "Distinguishing the Close-Packed 

Hexagonal and Face Centered Cubic Phases of the Metallization of Diamond by Polarization-Dependent Ex- 

tendedX-ray Absorption Fine Structure",J. Vac. Sci. Technol., B14,3207, (1996). 

K. M. Kemner, D. B. Hunter, W. T. Elam, and P. M. Bertsch, "Cesium XAFS Studies of Solution Phase Cs- 

Ionophore Complexation", Svnchrotron Radiation Techniaues in Industrial. Chemical and Materials Science, 

Plenum Press, pp. 149-158, (1996). 

K. M. Kemner, Y. U. Idzerda, V. G. Harris, V. Chakarian, W. T. Elam, C. -C. Kao, E. Johnson, Y. C. Feng, D. 

E. Laughlin, C. T. Chen, K. -K. Lee, and J. C. Lodder, "Direct Observation of Cr Magnetic Order in CoCrTa 

and CoCrPt Thin Films", J. App. Phys., 81, 1002, (1997). 

K. H. Kim, W. T. Elam, and E. F. Skelton, "Extended X-ray Absorption Fine Structure Study of Potassium 

Niobate", Mat. Res. Soc. Symp. Proc., 172,291, (1991). 

J. P. Kirkland, R. A. Neiser, H. Herman, S. Sampath, E. F. Skelton, D. Gansert, and H. G Wang, "Thermal 

Spraying of Superconducting Oxide Coatings", Adv Cev. Mat., 2/3B, 401, (1987). 

R.A. Neiser, J.P. Kirkland, W.T. Elam, and S. Sampath, "Optical Performance ofthe Naval Research 

Laboratory's Materials Analysis BeamLine at theNSLS", Nucl. Instrum. & Meth., A266,220, (1988). 

R.A. Neiser, J.P. Kirkland, W.T. Elam, H. Herman, S. Rangaswamy, V.M. Letourneau, and M. Osofsky, "Elec- 

trical, Chemical, and Structural Properties of Plasma Sprayed Y-Ba-Cu-Oxide Superconducting Coatings", 

Proceedings of MRS Svmp. On High Temperature Superconductors, 99,689-693, (1988). 

R.A. Neiser, J.P. Kirkland, H. Herman, W.T. Elam, and E.F. Skelton, "Plasma Sprayed Superconducting Oxide 

Coatings", Mat. Sci. and Engin., 91, L13, (1 987). 

G.S. Nolas, V.G. Harris, G.A. Slack, D.T. Morelli, and T.M. Tritt, "Low-Temperature Transport Properties of 

the Mixed-Valence Semiconductor Ru,,~P~,,~S~,",J. Appl. Phys., 80111,6304, (1996). 

S.A. Oliver, V.G. Harris, C.Vittoria, W.T. Elam, K.H. Kim, H.H. Hamdeh, and M. Alhabash, "Magnetic 

Properties and Local Ordering During Thermal Annealing ofAmorphous Fe,,Ni,B15Si5 Films", J. Appl. Phys., 70, 

5842, (1991).

D.P. Pappas, J.W. Glesener, V.G. Harris, Y.U. Idzerda, J.J. Krcbs, and G.A. Prinz, "Growth of FCC-Fc Filnis on 

Diamond", Aypl. P11y.s. Lett., 64,28, (1 994). 

D.P. Pappas, J.W. Glesener,V.G. Harris, J.J. Krcbs, Y.U. Idzerda, A.A. Morrisli, and G.A. Prinz, "Epitaxial 

Growth of FCC Fe and Cu Filnis on Diamond", Proc. Of Mat. Rcs. Soc. 313,369, (1 993). 

D.P. Pappas, V.G. Harris, H.A. Hoff, and G. Waytena, "Stabilization of Singlc Crystal FCC Fc on Dianiond", 

Mat. Res. Soc. Symp. Proc., 339,241, (1 994). 

S.B. Roscoe, A.K. Kakkar, T.J. Marks, A. Malik, M.K. Durbin, W. Lin, G.K. Wong. and P. Dutta, "Sclf- 

Assembled Chromophoric NLO Monolayers: X-ray Reflectivity as a Probe of Building Block-film Microstructure 

Relationships", Langrmrir, 12,42 18, (1 996). 

A. Shih, C. Hor, W. Elam, J. Kirkland, and D. Mucller, "Surface Geometry of BaO on W(100): A Surfacc- 

Extended X-ray-Absorption Fine-Structure Study", P1ij:s. Rev., B44,58 18, ( 199 I). 

P. Skeath, W. T. Elani, W. K. Burns, F. A. Stcvie, and T. H. Briggs, "Conccntration Dcpcndcricc of tlic Octalic- 

dral Ti4' Center in LiNbO,: Its Effect on Refractive Indices", P11jx Re\'. Lett., 59, 1950, (1 987). 

E.F. Skelton, W.T. Elam, D.U. Gubser, S.H. Lawrence, M.S. Osofsky, L.E. Totli, and S.A. Wolf, "Tcnipcraturc- 

Dependent X-Ray Studies of the High Tc Supcrconductor La,,,Ba ,,,, CuO,", Pl~j!~.s. Ra?., B35,7 140, ( 1987). 

J.E. Snyder, V.G. Harris, J.W. Harrcll, F.T. Parker, and S. Kitahata. "Local Structure of as-fabricatcd and 

Partially-Reduced Co,Ti,Sn-Substituted Ba-hexaferrite Powdcr", J. Aj~jd. Pl~ys., 8115.3824, (1 997). 

J. E. Snyder, V.G. Harris, N.C. Koon, X. Sui, and M.H. Kryder, "Local Structure of the Amorphous Precursor to 

Ba-Hexaferrite Thin Filnis: An Anisotropic Octahedral Fe-0 Glass Network", Pl~js. Re\,. Lett., 77,3383, (1 996). 

J. E. Snyder, V.G. Harris, N.C. Koon, X. Sui, and M.H. Kryder, "Determination of Local Structurc in tlic 

Amorphous Precursors to Ba-Hexaferrite Thin Filnis",J. Aj~pl. PII~:T., 7918,489 1, (1 996). 

J. E. Snyder, V.G. Harris, N.C. Koon, X. Sui, and M.H. Kryder, "Local Anisotropic Structurc in Aniorp1ious Ba- 

Fe-0 Films and its Role in Determining Magnetic Anisotropy in Crystallized Ba-Hcxafcrritc Filnis", IEEE Tt~ins. 

on Magn., 3116,3844, (1995). 

X. Sui, M. Scherge, M.H. Kryder, J.E. Snyder, V.G. Harris, and N.C. Koon. "Barium Hcxafcrritc Thin Film 

Recording Media7',J. Mug. Mag. Muter., 155,132, (1 996). 

R. Swineford, D. Pappas, and V.G. Harris, "Structurc of C-Stabilized fcc Fc on Dianiond: Thc Growth of Singlc 

Crystal Austenite", Plzys. Rev., B52,7890, (1 995). 

B. Amen, S.H. Southworth, J.C. Levin, U. Arp, T. LeBrun, and M.A. MacDonald, "Xcnon Spectator and 

Diagram L,-M4,,M4., Augcr Intensities near the L, Thrcshold", Plljs. Re\,., A56, R 1079, ( 1997). 

U. Arp, J.W. Cooper, T. LeBrun, S.H. Southworth, M. Jung, and M.A. MacDonald, "Angular Corrclation 

Between Ka Photons and L,,,-M,,,M,,, Auger Electrons Following Argon 1 s Photoionization",./. Plij~s. B: at Mol. 

Opt. Phys., 29, L837, (1996). 

U. Arp, T. LeBrun, S.H. Southworth, M.A. MacDonald, and M. Jung, "X-ray Fluorcsccncc and Augcr-Elcctron 

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J.D. Mills, J.A. Sheehy, T.A. Ferrett, S.H. Southworth, R. Mayer, D.W. Lindle, and P.W. Langhoff, "Nondipole 

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K.E. Miyano, Y. Ma, S.H. Southworth, P.L. Cowan, and B.A. Karlin, "Resonant Raman Scattering in Potassium 

and Chlorine KP X-ray Emission from KCL", Phys. Rev., B54,12022, (1 996). 

Beamline X24C 

M.P. Kowalski, R.G. Cruddace, J.F. Seely, J.C. Rife, K.F. Heidemann, U. Heinzmann, U. Kleineberg, K. 

Osterried, and D. Menke, "Efficiency of a Multilayer-Coated, Ion-Etched Laminar Holographic Grating in the 

14.5-16.0-nm WavelengthRegion", Optics Letts., 22,834, (1997). 

M.P. Kowalski, R.G. Cruddace, J.F. Seely, J.C. Rife, W.R. Hunter, and T.W. Barbee, Jr., "The EUV Perfor- 

mance of an Ion-Etched BlazedDiffraction GratingV,J. Electr. Spectro. Rel. Phenom., 80,473, (1996). 

W.R.L. Lambrecht, S.N. Rashkeev, B. Segall, K. Lawniczak-Jablonska, T. Suski, E.M. Gullikson, J.H. 

Underwood, R.C.C. Perera, J.C. Rife, I. Gregory, S. Porowski, andD.K. Wickenden, "X-Ray Absorption, 

Glancing-Angle Reflectivity, and Theoretical Study of the N K- and Ga M,,,-Edge Spectra in GaN, Phys. Rev., 

B55,2612, (1997). 

J.F. Seely, M.P. Kowalski, R.G. Cruddace, J.C. Rife, T.W. Barbee, Jr., and W.R. Hunter, "High Resolution 

Spectroscopy using Normal-Incidence Multilayer Gratings", W and X-ray Spectroscopy of Astrophysical and 

Laboratory Plasmas, edited by K. Yamashita and T. Watanabe, Universal Academy Press, Tokyo, p. 225, (1 996). 

J.F. Seely, M.P. Kowalski, W.R. Hunter, and G. Gutman, "Reflectance of a Wideband Multilayer X-ray Mirror 

at Normal and Grazing Incidence", Appl. Optics, 35,4408, (1 996). 

Beamline X25 

H. Baltes, Y. Yacoby, R. Pindak, R. Clarke, L. Pfeiffer, and L.E. Berman, "Measurement ofthe X-Ray Diffraction 

Phase in a 2D Crystal", Phys. Rev. Lett., 79,1285, (1997). 

D.C. Boisvert, J. Wang , Z. Otwinowski, A.L.Honvich, and P.B.Sigler, "The 2.4 A Crystal Structure ofthe 

Bacterial Chaperonin GroEL Complexed with ATP Gamma S", Nut. Struct. Bio., 312,170-7, (1996). 

K. Braig, Z. Otwinowski, R. Hegde, D.C. Boisvert, A. Joachimiak, A.L. Honvich, and P.B. Sigler, "The Crystal 

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Q.R. Fan, L. Mosyak, C.C. Winter, N. Wagtmann, E.O. Long, and D.C. Wiley, "Structure of the Inhibitory 

Receptor for HumanNatural Killer Cells Resembles Haematopoietic Receptors", Nature, 389,96, (1 997). 

J.M. Gulbis, Z. Kelman, J. Hunvitz, M. 07Donnell, and J. Kuriyan, "Structure of the C-Terminal Region of 

p21WAF1'C1P1 Complexed with Human PCNA", Cell, 87,297, (1996). 

F. Guo, D.N. Gopaul, and G.D. Van Duyne, "Structure of Cre Recombinase Complexed with DNA in a Site- 

Specific Recombination Synapse", Nature, 389,40, (1997). 

J.P. Hill, C.-C. Kao, and D.F. McMorrow, "K-Edge Resonant X-Ray Magnetic Scattering from a Transition- 

Metal Oxide: NiO", Phys. Rev., B55, R8662, (1997).

S. Krishnan, J.J. Felten, J.E. Rix, J.K.R. Weber, P.C. Nordine, M.A. Beno, S. Ansell, and D.L. Price, "Levitation 

Apparatus for Structural Studies of High Temperature Liquids using Synchroton Radiation", Rev. Sci. Iri.str.lrn~., 

68,3512, (1997). 

H. Li, J.J. Dunn, B.J. Luft, and C.L. Lawson, "Crystal Structure of Lynie Disease Antigen Outer Surface Protein 

A Complexed with an Fab", Proc. Nut. Acad. Sci., 94,3584, (1 997). 

J.L. Libbert, J.A. Pitney, and I.K. Robinson, "Asymmetric Fraunhofer Diffraction from Roller-Blade Slitsw,./. 

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O.M. Magnussen, B.M. Ocko, M. Deutsch, M.J. Regan, P.S. Pershan, D. Abernathy, G. Griibel, and J.-F. 

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M.J. Regan, O.M. Magnussen, E.H. Kawamoto, P.S. Pershan, B.M. Ocko, N. Maskil, M. Deutsch, S. Lee, K. 

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205, 762, (1996). 

M.J. Regan, P.S. Pershan, O.M. Magnussen, B.M. Ocko, M. Deutsch, and L.E. Berman, "Capillary-Wavc 

Roughening of Surface-Induced Layering in Liquid Gallium", P11g:s. Re\3., B54,9730, (1 996). 

M.J. Regan, P.S. Pershan, O.M. Magnussen, B.M. Ocko, M. Deutsch, and L.E. Berman, "X-Ray Reflectivity 

Studies ofLiquid Metal and Alloy Surfaces", P1zj:s. Re\,., BSS, 15874, (1 997). 

M.J. Regan, H.C. Tostmann, P.S. Pershan, O.M. Magnussen, E. DiMasi, B.M. Ocko, and M. Deutsch, "Oxidation 

ofLiquid Gallium Surfaces: X-Ray Reflectivity Study", Pl~jx Re\>., BS5,10786, (1 997). 

F. Sieheri, I. Moarefi, and J. Kuriyan, "Crystal Structure of the Src Family Tyrosine Kinase Hck", Nrrtwc, 385, 

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J.A. Simpson, R.A. Cowley, D.A. Jehan, R.C.C. Ward, M.R. Wells, D.F. McMorrow, K.N. Clausen, T.R. 

Thurston, and D. Gibbs, "Co-Existence of Long- and Short-Range Magnetic Correlations in Holmium-Erbium 

Superlattices", 2. Phys., B101,35, (1 996). 

M. Sriram, J. Osipiuk, B.C. Freeman, R.I. Morimoto, and A. Joachiniiak, "Human Hsp70 Molecular Chaper- 

one Binds Two Calcium Ions Within the ATPase Domain", Str-lrctlrre, 5,403, (1 997). 

Y. Wang, Y. Jiang, M. Meyering-Voss, M. Sprinzl, and P.B. Sigler, "Crystal Structure ofthe EF-TwEF-Ts 

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H. Wu, P.D. Kwong, and W.A. Hendriekson, "Dimeric Association and Segmental Variability in the Structure 

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Z. Xu, A.L. Horwich, and P.B. Sigler, "The Crystal Structure ofthe Asymnletric GroEL-GroES-(ADP), 

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Beamline X26A 

P.M. Bertsch, D.B. Hunter, P.R. Nuessle, and S.B. Clark, "Molecular Characterization ofContaminants in Soils 

by Spatially Resolved XRF & XANES Spectroscopy", J. dc Pligx IV, 7, C2-8 17, (1 997).

J.S. Delaney, S. Bajt, S.R. Sutton, andM.D. Dyar, "In Situ Microanalysis of Fe3+/ZFe Ratios in Amphibole by X- 

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W.P. Gates, D.B. Hunter, P.R. Nuessle, and P.M. Bertsch, "A Time Resolved XANES Study of an Organo-Clay 

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D.B. Hunter, P.M. Bertsch, K.M. Kernner, and S.B. Clark, "Distribution and Chemical Speciation of Metals and 

Metalloids in Biota Collected from Contaminated Environments by Spatially Resolved XRF, XANES and 

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H. S. Isaacs, and S.-M. Huang, "Behavior of Dissolved Molybdenum during Localized Corrosion ofAustenitic 

Stainless Steel",J. Electrochem. Soc., 143112, L277, (1996). 

R.A. Mayanovic, A.J. Anderson, and S. Bajt, "Microbeam XAFS Studies on Fluid Inclusions at High Tempera- 

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J. Rakovan, and R.J. Reeder, "Intracrystalline Rare Earth Element Distributions in Apatite: Surface Structural 

Influences on Incorporation During Growth", Geochimica et Cosmochimica Acta, 60,4435, (1 996). 

T. Tokunaga, G.E. Brown, Jr., I.J. Pickering, S.R. Sutton, and S. Bajt, "Selenium Redox Reactions and Transport 

BetweenPonded Waters and Shallow Sediments", Environ. Sci. & Technol., 31,1419, (1997). 

A. Zappal&, S. Bajt, G.E. Gigante, and A.L. Hanson, "Applications of EDXRF in the Conservation of Acid Papers 

using a Synchrotron Light Microbeam", Nucl. Instrum. andMeths. in Phys. Res., B117,145, (1996). 

Beamline X26C 

U.K. Genick, G.E. Borgstahl, K. Ng, Z. Ren, C. Pradervand, P.M. Burke, V. Srajer, T.Y. Teng, W. Schildkamp, 

D.E. McRee, and et al., "Structure of a Protein Photocycle Intermediate by Millisecond Time-Resolved Crystal- 

lography", Science, 275,1471, (1997). 

J.L. Jordan-Sweet, K. Evans-Lutterodt, G.S. Cargill, 111, M.A. Marcus, and I.C. Noyan, "Microbeam Diffraction 

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K. Moffat, and Z. Ren, "Synchrotron Radiation Applications to Macromolecular Crystallography", Current 

Opinion in Struct. Bio., 7,689, (1997). 

V. Stojanoff, D.P. Siddons, L.A. Monaco, P. Vekilov, and F. Rosenberger, "X-ray Topography of Tetragonal 

Lysozyme Grown by the Temperature-Controlled Technique", Acta Cryst., D53,588, (1 997). 

P.-C. Wang, G. S. Cargill 111, I. C. Noyan, E. G. Liniger, C.-K. Hu, and K. Y. Lee, "Real- Time Measurements 

of Thermal and Electromigration Strains on Individual A1 Interconnects by X-Ray Microdiffraction", Interna- 

tional Electron Devices and Materials Symposium Proceedings, A1110, 

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P.-C. Wang, G. S. Cargill 111, I. C. Noyan, E. G. Liniger, C.-K. Hu, and K.Y. Lee, "X-Ray Microdiffraction for 

VLSI", Mat. Res. Soc. Symw. Proc., 427,35, (1996).

Beamline X27A 

B.A. Dowd, "Workshop on X-ray Computed Microtomography: Applications & Techniques", 5jwIi. Rd. Ncw:v, 

10, 5, (1997). 

B.L. Illnian, and B.A. Dowd, "Synchrotron Applications in Forestry and Forest Products", Slwcli. R d. Ncw:~, 10, 

1, (1997). 

Beamline X27C 

D. Chapman, W. Thomlinson, F. Arfelli, N. Gmiir, Z. Zhong, R. Menk, R.E. Johnston, D. Washburn, E. 

Pisano, and D. Sayers, "Mammography Imaging Studies using a Lauc Crystal Analyzcr", Syricli. Rrrd. l/i.vtr.uni. 67, 

9, (1995), BNL 62394. 

R.E. Johnston, D. Washburn, E. Pisano, C. Burns, W. Thomlinson, L.D. Chapman, F. Arfclli, N.F. Gmiir, Z. 

Zhong, and D. Sayers, "Mammography Phantom Studies with Synchrotron Radiation", Rac/iolog\~, 20013,659, 

(1 996), BNL 62733.

NSLS STAFF 

M. Babzien, I. Ben-Zvi, P. Catravas, J. M. Fang, A. Fisher, W. S. Graves, X. Z. Qui, Z. Segalov, andX. J. Wang, 

"Optical Alignment and Diagnostics for the ATF Microundulator FEL Oscillator", Nucl. Instrum. and Meths. In 

Phys. Res., A375,420, (1 W6), BNL 638 1 1. 

M. Babzien, A. Fisher, I. Pogorelsky, and T. Srinivasan-Rao, "A High Stability Nd: YAG Photocathode Drive 

Laser", Technical, Digest Conference Proceedings, 15,218, (1 995), BNL 63263. 

H. Baltes, Y. Yacoby, R. Pindak, R. Clarke, L. Pfeiffer, and L. Berman, "Measurement ofthe X-ray Diffraction 

Phase in a 2D Crystal", Phys. Rev. Lett., 7917, 1285, (1997), BNL 64710. 

K. Bane, S. Krinsky, and J.B. Murphy, "Longitudinal Potential well Distortion due to the Synchrotron Radiation 

Wakefield", Micro Bunches Workshop AIP Conference Proceedings, American Institute of Physics Press, 367, 

191-98, (1996), BNL 63852. 

R. A. Bartynski, E. Jensen, S. L. Hulbert, and C.-C. Kao, "Auger Photoelectron Coincidence Spectroscopy Using 

Synchrotron Radiation", Progr. SurJ: Sci., 5312, 155, (1 996), BNL 64645. 

K. Batchelor, M. Babzien, I. Ben-Zvi, J. Fischer, I. Fisher, R. Malone, I. Pogorelsky, T. Srinivsan-Rao, J. 

Sheehan, and X.J. Wang, "Operational Experience on the Brookhaven National Laboratory Acceleration Test 

Facility", Proceedings of the 4th European Particle Accelerator Conference, London, England, edited by V. 

Suller, and C.H. Pette-Jean-Genez, World Scientific Publishing Co., Vol. 1, pp. 736-738, (1994), BNL 60739. 

L. Berman, "SPIE Conference on Optics for High-Brightness Synchrotron Radiation Beamlines II", Synch. Rad. 

News, 1011, 122, (1997), BNL 63691. 

E.B. Blum, M. Dienes, and J.B. Murphy, (Editors), Micro Bunches Workshop AIP Conference Proceedings 367, 

American Institute ofPhysics Press, NY, (1996), BNL 63824. 

E. Bozoki, S. Ramamoorthy, 0. Singh, Y. Tang, and A. Friedman, "Operations with the Digital Orbit Feedback 

System in the NSLS X-ray Ring", Proceedings of the Fifth European Particle Accelerator Conference, 3,19 1 1, 

(1996), BNL 62947. 

P. Catravas, R. Stoner, J. Blastos, D. Sisson, I. Mastrovsky, G. Bekefi, X.J. Wang, and A. Fisher, "MIT 

Microwiggler for Free Electron Laser Applications", Proceedings of 1995 Particle Accelerator Conference, pp. 

192-194, (1995), BNL 61957. 

D. Chapman, W. Thomlinson, R. E. Johnson, D. Washburn, E. Pisano, N. Gmiir, Z. Zhong, R. Menk, F. 

Arfelli, and D. Sayers, "Diffraction Enhanced X-ray Imaging", Phys. in Med. and Biol., 42,20 15, (1 997), BNL 

64698.

T.T. Chou, C.N. Yang, and L.H. Yu, "Monicntum Distribution for Bosons with Positivc Scattcring Length in a 

Trap", Phys. Rev., A55/2, 1 179, (1997), BNL 63778. 

C.L. Cleveland, U. Landman, T.G. Schaaff, M.N. Shafigullin, P.W. Stephens, and R.L. Whcttcn, "Structural 

Evolution of Smaller Gold Nanocrystals: The Truncated Decahcdral Motif', Plijx Rev. Lett., 79/10, 1873, 

(1997), BNL 64783. 

F.A. Dilnianian, X.Y. Wu, E.C. Parsons, B. Rcn, J. Kress, T.M. Button, L.D. Chapman. J.A. Codcrrc, F. Giron, 

D. Greenberg, D.J. Krus, Z. Liang, S. Marcovici, M.J. Petcrscn, C.T. Roquc, M. Shlcifcr, D.N. Slatkin, W.C. 

Thomlinson, K. Yamamoto, and Z. Zhong, "Single-and Dual-Energy CT with Monochromatic Synchrotron X- 

rays", Phj~s. Med. Biol., 42,37 I, (1 997), BNL 6282 1 . 

P. Dumas, M. Suhren, Y. J. Chabal, C. J. Hirschmugl, and G. P. Williams, "Adsorption and Rcactivity of NO on 

Cu(l11): A Synchrotron Infrared Reflection Absorption Spectroscopic Study", Sw$ Sci., 371,200, (1 997), BNL 

64673. 

C. L. Foerster, C. Lanni, I. Maslennikov, and W. Turner, "Photon Dcsorption Mcasurcmcnts of Coppcr and 

Copper Plated Beam Tubcs for the SSCL 20 TcV Proton Collidcr", J. Vuc. Sci. Teclinol., A1214, 1673, (1 994), 

BNL 64720. 

W. S. Graves, "Gain and Startup Conditions for the BNL Visible FEL Oscillator Expcrimcnt", Nucl. In.vtr.u~n. 

and Meth. in Phjts. Res., A393,2 10, (1997), BNL 63986. 

W.S. Graves, L. Solomon, and I. Lehrman, "End Fields in the Harnionic Generation Supcrconducting FEL at 

BNL-NSLS", Nzrcl. Instrwnz. and Meths. in PI1j:c.. Rex., A358,4 14, (1 995), BNL 63809. 

K. Hamalainen, S. Manninen, C.-C. Kao, W. Caliebc, J.B. Hastings, A. Bansil, S. Kaprzyk, and P.M. Platzman. 

"High Resolution Compton Scattering Study of Be", Pliys. Re\,., B54/8,5453, (1 996), BNL 63773. 

M. Hart, "Powder Diffraction", Rontren Centennial, X-raw in Natural and Life Sciences, edited by A. Haasc, G. 

Landwehr, and E. Umbach, World Scientific Publishing Co., pp. 647-658, (1997), BNL 62630. 

J. Kircher, P.L. Richards, R. Henn, M. Cordona, and G.P. Williams, "Far Infrared Ellipsomctry Using Synchro- 

tron Radiation", J. Opt Soc. An!., B14/4,705, (1997), BNL 61 880. 

Y. Liu, S.A. Bogacz, D.B. Cline, X.J. Wang, I.V. Pogorelsky, and W.D. Kiniura, "Micro Bunching Diagnostics 

for the ICA by Coherent Transition Radiation", Micro Bunches Workshop. AIP Confcrcncc Procccdings 367, 

pp. 445-454, (1995), BNL 62387. 

Y. Liu, D. Cline, I. Ben-Zvi, X.J. Wang, J. Sheehan, K. Batchclor, R. Malonc, and M. Issapour, "A Modified 

Feed-Forward Control System and the ATF", Rev. of Sci. I~utrwi., 6812, 1 137, (1 997). BNL 63384. 

D.R. Lynch, L. Berman, P. Montanez, S. Pjerov, P. Stefan, and M. Woodle, "Beryllium Windows for Synchrotron 

Light Sources" SPIE, 2855, 119, (1996), BNL 63637. 

R.H. Menk, W. Thomlinson, N. Gmiir. Z. Zhong, D. Chapman, F. Arfclli, W.R. Dix, W. Gracff, M. Lohniann, 

G. Illing, L. Schildwacher, B. Reimc, W. Kupper, C. Hanim, J.C. Giaconiini, H.J. Gordon, E. Rubcnstcin, J. 

Dervan, H.J. Besch, and A.H. Walenta, "The Concept of Spatial Frequency Dcpcnding DQE and it's Application 

to a Comparison of two Detectors Used in Transvenous Coronary Angiography", Nuel. In.vtr.l~ni. ~ nMdh. d 

In Phys. Res., A398,35 1, (1 997), BNL 64757. 

J. B. Murphy, S. Krinsky, and R. L. Gluckstern, "Longitudinal Wakefield for an Electron Moving on a Circular 

Orbit", ParticleAcceIer.utor:c., 

57,9, (1 997), BNL 63090.

T. Nanba, Y. Nodake, M. Muneyasu, G. P. Williams, and S. Hayashi, "Size-Dependence of Phase Transition of 

Cds Microcrystals", J. Phys. Soc. Japan, 6615,1526, (1 997), BNL 6467 1. 

D. Robin, J. Safranek, G. Portmann, and H. Nishimura, "Model Calibration and Symmetry Restoration of the 

Advanced Light Source", Proceedings ofthe European Particle Accelerator Conference, p. 97 1, (1 996), BNL 

64140. 

J. L. Rothrnan, "Ultra-fast Monocycle Generator", Electronic Design, 522,102, (1996), BNL 64006. 

J. Safranek, "Experimental Determination of Storage Ring Optics using Orbit Response Measurements", Nucl. 

Instrum. andMeths., A388,27-36, BNL 63382. 

J. Safranek, "Performance Optimization of Synchrotron Light Sources", SPIE, 2856,2-15, (1996), BNL 641 39. 

J. Safranek, and P.M. Stefan, "Emittance Measurement at NSLS X-ray Ring", Proceedings ofthe European 

Particle Accelerator Conference, p. 1573, (1 996), BNL 64 14 1. 

0. Singh, S. Krinsky, P.M. Ivanov, and E.A. Medvedko, "Orbit Compensation for the Time Varying Elliptically 

Polarized Wiggler", Rev. Sci. Instrum., 6719,l, (1996), BNL 63952. 

L. Solomon, W. S. Graves, and I. Lehrman, "Magnetic Field Measurements of the Harmonic Generation FEL 

Superconducting Undulator at BNL-NSLS", Nucl. Instrum. and Meths. in Phys. Res., A358,4 1 1, (1 995), BNL 

63810. 

L. H. Tjeng, B. Sinkovic, N. B. Brookes, J. B. Giedkoop, R. Hesper, E. Pellegrin, F.M.F. de Groot, S. Altieri, S. 

L. Hulbert, E. Shekel, and G. A. Sawatzky, "Spin-Resolved Photoemission on Anti-Ferromagnets: Direct Obser- 

vation of Zhang-Rice Singlets in CuO", Phys. Rev. Lett., 78,1126, (1997), BNL 64219. 

X.J. Wang, and I. Ben-Zvi, "High-Brightness Electron Beam Diagnostics at the ATF", AIP Conference Proceeda, 

390,232-239, (1996), BNL 63 15 1. 

X. J. Wang, I. Ben-Zvi, and Z. Segalov, "Experimental Characterization of ATF Beam Position Monitor", Pro- 

ceeding: ofthe Fifth European Particle Accelerator Conference, pp. 1576-1 578, (1996), BNL 632 14. 

X.J.Wang, X. Qiu, and I. Ben-Zvi. "Experimental Observation of Micro-Bunching in a Photocathode RF Gun 

Injector", Phys. Rev. Letts., B54, R3 121, (1996), BNL 62820. 

D. L. Wetzel, J. A. Reffner, and G. P. Williams, "Synchrotron-Powered FT-IRMicrospectroscopy: Single Cell 

Interrogation", Mikrochim. Acta, 14,353, (1997), BNL 64672. 

B. Winn, H. Ade, C. Buckley, M. Howells, S. Hulbert, C. Jacobsen, J. Kirz, I. McNulty, J. Miao, T. 

Oversluizen, I. Pogorelsky, and S. Wirick, "X1 A: Second-Generation Undulator Beamlines Serving Soft X-ray 

Spectromicroscopy Experiments at the NSLS", Rev. Sci. Instrum., 6719,3359, (1996), BNL 64279. 

Z. Yin, L. Berman, S. Dierker, E. Dufresne, and D. P. Siddons, A Simple X-ray Focusing Mirror using Float 

Glass", SPIE, 2856,307, (1996), BNL 63583. 

L. H. Yu, "Quantum Tunneling in a Dissipative System", Phys. Rev., A54/5,3779, (1996), BNL 64041. 

L.H. Yu, and I. Ben-Zvi, "High Gain Harmonic Generation of Soft X-rays with the Fresh Bunch Technique", 

18th International Free Electron Laser Conference, Nucl. Instrum. And Meths. In Phys. Res., A393,96, (1 997), 

BNL 63639.

Z. Zhong, D. Chapman, R. Menk, J. Richardson, S. Theophanis, and W. Thonilinson, "Monochromatic 

Energy-Subtraction Radiography using a Rotating Anode Source and a Bent-Laue Monochroniator", Pl7y.c.. in 

Med. and Bid, 42, 175 1, (1 997), BNL 64 155. 

Z. Zhong, D. Chapman, W. Thonilinson, F. Arfelli, and R. Menk, "A Bent-Laue Crystal Monochroniator for 

Monochromatic Radiography with an Area Beam", Nzrcl. It~.str.un~. a17d Mcth. in P1ij:s. Rex, A399,489, ( 1997), 

BNL 64 1 54.

BNL FORMAL AND INFORMAL REPORTS 

I. Ben-Zvi, R. Fernow, J. Gallardo, M. Hart, J. Hastings, E. Johnson, S. Krinsky, R. Palmer, andL.-H. Yu, 

"Lepton Accelerators and Radiation Sources: R&D Investment at BNL", BNL 64214, March 1997. 

J. Dunsmuir, P. Spanne, C. Jacobsen, A. Dilmanian, Z. Zhong, B. Dowd, B. Illman, B. Lindquist, S.R. Song, 

and B. Andrew, "X-ray Computed Microtomography Workshop 1997", BNL 64772, September 1997. 

S. Krinsky, "Storage Ring Working Group Report", Micro Bunches Workshop, Upton, NY, BNL 63987, 

September 1995. 

E.Z. Rothman, and J.B. Hastings, (Editors), "1996 Activity Report", National Synchrotron Light Source, BNL 

525 17, November 1996. 

X.J. Wang, and D. Kehne, "Measurements of Emittance Growth Through the Achromatic Bend at the BNL 

Accelerator Test Facility", BNL 64646, July 1997.

Report Number (I 4) BNL ' ' 35 $b 

Publ. Date (1 1) /99865 

Sponsor Code (I 8) Dog IGR j X 1; . 

u c Category (I 9) L(c - 300 , 

: @ E/~K 

DOE

4 - Brookhaven National Laboratory

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