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JOURNAL DE PHYSIQUE Tome 47 Colloque C8, supplement au n° 12 Decembre 1986 EX Α FS and Near Edge Structure IV July 7-11, 1986 Abbaye Royale de Fontevraud (France) Edited by : P. LAGARDE D. RAOUX J. PETIAU Vol. 1 les editions d<2 plujaque Avenue du Hoggar, Zone Industrielle de Courtaboeuf, Β.P. 112, 91944 Les Ulis Cedex, France

Transcript of EX Α FS and Near Edge Structure IV - uni- · PDF fileEX Α FS and Near Edge...

JOURNAL DE PHYSIQUE Tome 47 Colloque C 8 , supplement au n° 12 Decembre 1986

EX Α FS and

Near Edge Structure IV

July 7-11, 1986 Abbaye Royale de Fontevraud

(France)

Edited by : P. LAGARDE D. RAOUX J. PETIAU

Vol. 1

les editions

d<2 plujaque

Avenue du Hoggar, Zone Industriel le de Courtaboeuf,

Β . P . 112, 91944 Les Ulis Cedex, France

CONTENTS

Volume 2

FUNDAMENTAL ASPECTS OF EXAFS AND XANES

Ε. A. STERN. - O t h e r EXAFS-like phenomena C8-3

CR. NATOLI and M. BENFATTO. - A u n i f y i n g scheme o f i n t e r p r e ­t a t i o n o f X-ray a b s o r p t i o n s p e c t r a based on t h e m u l t i p l e s c a t t e r i n g t h e o r y C8-11

M. BENFATTO, C.R. NATOLI, J. GARCIA and A. BIANCONI.- D e t e r m i ­n a t i o n o f t h e t h i r d o r d e r m u l t i p l e s c a t t e r i n g s i g n a l i n t e t r a h e d r a l c l u s t e r s i n l i q u i d s o l u t i o n s C8-25

J.J. REHR, R.C. ALBERS, C.R. NATOLI and Ε.A. STERN.- S p h e r i c a l wave c o r r e c t i o n s i n XAFS C8-31

Y.A. BABANOV and V.R. SHVETSOV.- Bond l e n g t h d e t e r m i n a t i o n f o r m u l t i c o m p o n e n t systems - New o p p o r t u n i t i e s i n EXAFS d a t a a n a l y s i s C8-37

L.T. WILLE, P.J. DURHAM and P.A. STERNE.- X-ray a b s o r p t i o n i n i o n i c m a t e r i a l s C8-43

J. GARCIA, A. BIANCONI, Μ. BENFATTO and C.R. NATOLI.- C o o r d i ­n a t i o n geometry o f t r a n s i t i o n m e t a l i o n s i n d i l u t e s o l u ­t i o n s by XANES C8-49

A.G. McKALE, S.-K. CHAN, B.W. VEAL, A.P. PAULIKAS and G.S. KNAPP.- Improved d e t e r m i n a t i o n o f b a c k s c a t t e r i n g am­p l i t u d e and phase s h i f t f u n c t i o n s C8-55

A. BALERNA, M. BENFATTO, S. MOBILIO, C.R. NATOLI, A. FILIPPONI and F. EVANGELISTI.- S p h e r i c a l wave a n a l y s i s and m u l t i p l e s c a t t e r i n g e f f e c t s i n h y d r o g e n a t e d amorphous s i l i c o n C8-63

D. LU and J.J. REHR.- S e m i c l a s s i c a l t r e a t m e n t f o r i n e l a s t i c p r o c e s s e s i n EXAFS C8-67

A. D I CICCO, N.V. PAVEL, A. BIANCONI, M. BENFATTO and C.R. NATOLI.- S p h e r i c a l waves EXAFS and m u l t i p l e s c a t t e r i n g e f f e c t s i n XANES o f t h e K-edge s p e c t r u m o f s i l i c o n C8-71

B. LENGELER.- T r a n s f e r a b i l i t y o f s c a t t e r i n g a m p l i t u d e s and phases i n EXAFS between n e i g h b o r i n g e l e m e n t s i n t h e pe­r i o d i c t a b l e C8-75

X V I I I

S. BODEUR and I . NENNER.- I n n e r s h e l l resonances i n p h o t o -a b s o r p t i o n s p e c t r a o f gas phase s i l i c o n compound m o l e c u l e s C8-79

A.G. KOCHUR, A.M. NADOLINSKY and V.F. DEMEKHIN.- On t h e n a t u r e o f n o n s t r u c t u r a l low-R peak i n F o u r i e r t r a n s f o r m s o f some EXAFS-spectra C8-83

R.V. VEDRINSKII and L.A. BUGAEV.- S p h e r i c a l wave approach t o l e c t r o n f o c u s i n g p r o c e s s e s i n EXAFS C8-89

V.L. KRAIZMAN, A.A. NOVAKOVICH and V . l . POPOV.- Some a n a l y t i c a l p r o p e r t i e s o f t h e o n e - e l e c t r o n Green's f u n c t i o n a t XANES range C8-93

I . I . GEGUSIN and V.N. DATSYUK.- S i n g l e - s i t e a p p r o x i m a t i o n v i a i d e a l c r y s t a l Green's f u n c t i o n : XANES o f a l k a l i h a l i d e s . . C8-97

L.A. BUGAEV, I . I . GEGUSIN, A.A. NOVAKOVICH and R.V. VEDRINSKII.-C r y s t a l p o t e n t i a l and s i z e e f f e c t s i n XANES K - s p e c t r a o f a l k a l i h a l i d e s C8-101

EXPERIMENTAL TECHNIQUES

Y. YACOBY and A. AGRANAT.- Comparison o f t h e EXAFS s p e c t r a o f NaTa0 3 and KTa0 3 C8-107

L. BOSIO, R. CORTES and G. FOLCHER.- A l a b o r a t o r y ReflEXAFS measurement s y s t e m C8-113

A. BALERNA, R. BUSCHERT, M.D. GIARDINA, D. INZAGHI and S. MOBILIO.- H i g h r e s o l u t i o n EXAFS-XANES s p e c t r o m e t e r C8-117

B. R. DOBSON, S.S. HASNAIN, M. HART, M.J. VAN DER HOEK and P. VAN ZUYLEN.- An i n v e s t i g a t i o n o f t h e p e r f o r m a n c e o f a n o v e l d o u b l e c r y s t a l X - r a y monochromator f o r EXAFS and XANES measurements C8-121

R.F. PETTIFER and C. HERMES.- An X-ray monochromator s u i t a b l e f o r s t u d y i n g b i o l o g i c a l systems C8-127

T. MURATA, T. MATSUKAWA, M. MORI, M. OBASHI, S . - I . NAO-E, H. TERAUCHI, Y. NISHIHATA, 0. MATSUDO and J . - I . YAMAZAKI.-A d o u b l e c r y s t a l monochromator f o r s o f t X-ray beam l i n e o f UVSOR C8-135

H. OYANAGI, T. MATSUSHITA, U. KAMINAGA and H. HASHIMOTO.-L i n e a r d e t e c t o r f o r t i m e - r e s o l v e d EXAFS i n d i s p e r s i v e mode C8-139

A. RETOURNARD, M. LOOS, I . ASCONE, J. GOULON, M. LEMONNIER and R. CORTES.- A s i l i c o n p h o t o d i o d e a r r a y d e t e c t o r c o v e r ­i n g a l a r g e s o l i d a n g l e f o r f l u o r e s c e n c e EXAFS measurements f r o m 2 t o 25 keV C8-143

F.W. LYTLE, R.B. GREEGOR, G.H. VIA, J.M. BROWN and G. MEITZNER. -Gas phase X - r a y a b s o r p t i o n s p e c t r o s c o p y w i t h an e l e c t r o n y i e l d d e t e c t o r C8-149

T.K. SHAM, R.A. HOLROYD and R.C. MUNOZ.- X-ray a b s o r p t i o n mea­sur e m e n t s o f o r g a n i c s o l u t i o n s o f o r g a n o m e t a l l i c s w i t h s c i n t i l l a t i o n c o u n t i n g methods C8-153

XIX

K . I . PANDYA, Κ. YANG, R.W. HOFFMAN, W.E. 0 1 GRADY and D.E. SAYERS.- E l e c t r o n y i e l d d e t e c t o r s f o r n e a r s u r f a c e EXAFS a t a t m o s p h e r i c p r e s s u r e C8-159

J. BAINES, CD. GARNER, S.S. HASNAIN and C. MORRELL. - D e t e c ­t i o n systems f o r f l u o r e s c e n c e EXAFS measurement C8-163

S. AFFROSSMAN, S. DOYLE, G.M. LAMBLE, M.A. MORRIS, K.J. ROBERTS, D.B. SHEEN, J.N. SHERWOOD, R.J. OLDMAN, D. HALL, R.J. DAVEY and G.N. GREAVES.- The s u r f a c e s e n s i t i v i t y o f f l u o r e s c e n c e EXAFS a t r e f l e c t i o n c o n d i t i o n s C8-167

D. ARVANITIS, U. DOBLER, L. WENZEL, Κ. BABERSCHKE and J. STOHR.-A new t e c h n i q u e f o r submonolayer NEXAFS : f l u o r e s c e n c e y i e l d a t t h e c a r b o n Κ edge C8-173

G. THORNTON, D.R. WARBURTON, I.W. OWEN, C.H. RICHARDSON, R. McGRATH, I . T . McGOVERN and D. NORMAN.- The use o f p h o t o n s t i m u l a t e d i o n d e s o r p t i o n SEXAFS i n t h e d e t e r m i n a ­t i o n o f s u r f a c e s t r u c t u r e C8-179

K. ASAKURA, Y. SATOW and H. KURODA.- Ce K-edge EXAFS s p e c t r u m o f Ce0 2 C8-185

K. OHSUMI, S. SUENO, I . ΝΑΚΑ I , M. IMAFUKU, H. MORIKAWA, Μ. KIMATA, M. NOMURA and 0. SHIMOMURA.- EXAFS measurement under h i g h p r e s s u r e by diamond a n v i l c e l l C8-189

H. VAN BRUG, F. BIJKERK, H.C. GERRITSEN, K. MURAKAMI and M.J. VAN DER WIEL.- Time r e s o l v e d X - r a y a b s o r p t i o n measu­rements on p u l s e d l a s e r i r r a d i a t e d t h i n s i l i c o n f o i l s and s i l i c o n plasmas C8-193

A.P. HITCHCOCK and I . I S H I I . - Carbon and ox y g e n K - s h e l l EXAFS o f gases s t u d i e d by e l e c t r o n e n e r g y l o s s s p e c t r o s c o p y C8-199

K.M. CHOUDHARY, S.T. KIM, J.H. LEE, S.N. SHAH, M.L. DEN BOER, G.P. WILLIAMS and G.M. ROTHBERG.- P h o t o e m i s s i o n EXAFS mea­surements o f A l - 0 bond l e n g t h s i n A l f i l m s C8-203

E. CHAINET, J. DERRIEN, R.C. CINTI, T.T.A. NGUYEN and M. DE CRESCENZI.- Extended f i n e s t r u c t u r e s i n t h e Auger s p e c t r a C8-209

J. J . REHR, J. MUSTRE DE LEON, C.R. NATOLI and C S . FADLEY.-S p h e r i c a l wave c o r r e c t i o n s i n ARPEFS C8-213

CATALYSTS

H. DEXPERT.- A c t i v a t i o n o f r e f o r m i n g c a t a l y s t s : r e a c t i v i t y and k i n e t i c s t u d i e s u s i n g EXAFS C8-219

F. B.M. DUIVENVOORDEN, B.J. KIP, D.C KONINGSBERGER and R. PRINS.- D e t e r m i n a t i o n o f t h e m e t a l p a r t i c l e s i z e o f s u p p o r t e d P t , Rh, and I r c a t a l y s t s . A c a l i b r a t i o n o f h y d r o ­gen c h e m i s o r p t i o n by EXAFS C8-227

K. MOLLER and Τ. BEIN.- EXAFS s t u d i e s on t h e r e d u c t i o n o f P d ( I I ) i n X z e o l i t e s C8-231

XX

B. S. CLAUSEN, Β. LENGELER, B.S. RASMUSSEN, W. NIEMANN and H. TOPSOE.- X- r a y a b s o r p t i o n s p e c t r o s c o p y s t u d y o f Cu-based m e t h a n o l c a t a l y s t s . 2. Reduced s t a t e C8-237

C. ESSELIN, Ε. BAUER-GROSSE, J. GOULON, C. WILLIAMS, Y. CHAUVIN, D. COMMEREUC and E. FREUND.- EXAFS s t u d y o f n i c k e l and i r o n p r e c u r s o r s o f homogeneous Z i e g l e r - t y p e h y d r o g e n a t i o n c a t a l y s t s C8-243

Y. UDAGAWA, K. TOHJI, Z.Z. L I N , T. OKUHARA and M. MISONO.-C a t a l y s t s t r u c t u r e s t u d i e d by a l a b o r a t o r y EXAFS f a c i ­l i t y : R u / A l 2 0 3 C8-249

D. C. KONINGSBERGER, F.B.M. DUIVENVOORDEN, B.J. KIP and D.E. SAYERS.- The e f f e c t o f gas e n v i r o n m e n t ( H 2 , 0 2 ) on t h e s t r u c t u r a l p r o p e r t i e s o f s m a l l i r i d i u m m e t a l p a r t i c l e s s u p p o r t e d on Ύ - Α 1 2 0 3 as d e t e r m i n e d by EXAFS C8-255

D.C. KONINGSBERGER, H.H. LAMB, P.S. KIRLIN, M.J. KELLY and B.C. GATES.- An EXAFS s t u d y o f t h e f o r m a t i o n o f s m a l l m e t a l a g g r e g a t e s on MgO u s i n g o r g a n o m e t a l l i c compounds as p r e c u r s o r s C8-261

J. BERDALA, E. FREUND and J.P. LYNCH.- Genesis o f t h e m e t a l l i c phase i n a h i g h l y d i s p e r s e d c a t a l y s t formed f r o m P t a c e t y l a c e t o n a t e on a l u m i n a C8-265

J. BERDALA, E. FREUND and J. P. LYNCH.- Env i r o n m e n t o f p l a t i n u m atoms i n a H 2 P t C l 6 / A l 2 0 3 c a t a l y s t : i n f l u e n c e o f m e t a l l o a d i n g and c h l o r i n e c o n t e n t C8-269

Τ. YOKOYAMA, N. KOSUGI, K. ASAKURA, Y. IWASAWA and H. KURODA.-Tem p e r a t u r e dependence o f t h e Pt L 3-edge EXAFS o f p l a t i n u m c l u s t e r s s u p p o r t e d on N a Y - z e o l i t e C8-273

T. BEIN, S.J. McLAIN, G.D. STUCKY, G. WOOLERY, D.E. SAYERS and K. MOLLER.- EXAFS s t u d y o f n i c k e l t e t r a c a r b o n y l and N i - c l u s t e r s i n z e o l i t e Y C8-277

G. WOOLERY, G. KUEHL, A. CHESTER, T. BEIN, G. STUCKY and D.E. SAYERS.- EXAFS s t u d y o f N i exchanged i n t o z e o l i t e Y.. C8-281

M. LOOS, J. GOULON, M. BERTUCCI and R. BACHELARD.- S t r u c t u r a l s t u d i e s by EXAFS/XANES s p e c t r o s c o p i e s o f t h e a c t i v e s p e c i e s c a t a l y s i n g t h e o x y c h l o r a t i o n o f e t h y l e n e C8-285

LUNG-SHAN KAU, E . I . SOLOMON and K.O. HODGSON.- XANES/EXAFS s t u d y o f t h e c o p p e r a c t i v e s i t e i n methanol s y n t h e s i s c a t a l y s t C8-289

D. BAZIN, H. DEXPERT, P. LAGARDE and J.P. BOURNONVILLE.- Pt-Re on a l u m i n a r e f o r m i n g c a t a l y s t s a t t h e r e d u c e d s t e p C8-293

B. MORAWECK, P. BONDOT, D. GOUPIL, P. FOUILLOUX and A.J. RENOUPREZ.- Edge and EXAFS s t u d y o f c h a r c o a l s u p p o r t e d Pt-Fe c a t a l y s t s C8-297

H. KURODA, T. YOKOYAMA, N. KOSUGI, Μ. ICHIKAWA and T. FUKUSHIMA.- EXAFS s t u d y on S i 0 2 - s u p p o r t e d Rh-Fe and Pd-Fe b i m e t a l l i c c a t a l y s t s C8-301

V. PAUL-BONCOUR, A. PERCHERON-GUEGAN, J.C. ACHARD,

XXI

J. BARRAULT, Η. DEXPERT and R.C. KARNATAK.- EXAFS and NES s t u d i e s o f r a r e e a r t h and t r a n s i t i o n m e t a l c a t a l y s t s . . C8-305

F. LE NORMAND, K. KOFFI, L. HILAIRE, P. BERNHARDT and G. KRILL.- I n f l u e n c e o f c e r i u m c o n t e n t and o f t r a n s i t i o n m e t a l on t h e c e r i u m 1*τιι a b s o r p t i o n o f Pd-Ce/TA1 20 3

c a t a l y s t s C8-309

A. CLOZZA, J. GARCIA, A. BIANCONI and A. CORMA.- L o c a l s t r u c ­t u r e i n b i f u n c t i o n a l NiO-Mo0 3 z e o l i t e c a t a l y s t by K-Ni EXAFS and XANES s p e c t r o s c o p y C8-313

K. ASAKURA, Y. IWASAWA and H. KURODA.- EXAFS and XANES s t u d i e s on t h e l o c a l s t r u c t u r e s o f m e t a l i o n s i n m e t a l doped MgO systems C8-317

R.J. OLDMAN.- I n d u s t r i a l a p p l i c a t i o n s o f EXAFS/XANES C8-321

J. EVANS, J.T. GAUNTLETT and H. LEACH.- EXAFS s t u d i e s o f L e w i s a c i d p r o moted homogeneous c a t a l y s t s C8-327

G. DALBA, P. FORNASINI, F. ROCCA, P. PERTICI and E. BURATTINI.-EXAFS s t r u c t u r a l s t u d i e s o f a r o m a t i c p o l y m e r s / r u t h e n i u m c a t a l y s t s C8-331

P.B. WELLS, P. WORTHINGTON, M.S. ROBERTS and R.B. MOYES.-EXAFS s p e c t r o s c o p y o f s u p p o r t e d osmium c l u s t e r s C8-335

Ν. BINSTED, S.L. COOK, J. EVANS and G.N. GREAVES.- EXAFS s t u d i e s o f o x i d e s u p p o r t e d osmium c a r b o n y l c l u s t e r s C8-339

D. BALLIVET-TKATCHENKO, C. ESSELIN and J. GOULON.- EXAFS s t u d y o f s o l u b l e d i n i t r o s y l i r o n and c o b a l t complexes c a t a l y s i n g s p e c i f i c t r a n s f o r m a t i o n s o f o l e f i n s C8-343

COVALENTS

D.E. SAYERS and M.A. PAESLER.- X-ray a b s o r p t i o n s t u d i e s o f amorphous s e m i c o n d u c t o r s C8-349

A. FILIPPONI, P. FIORINI, F. EVANGELISTI, A. BALERNA and S. MOBILIO.- Amorphous h y d r o g e n a t e d a l l o y s : a c o m p a r a t i v e EXAFS s t u d y o f a - S i 1 _ x C x : H , a - S i 1 _ x G e x : H , a-SiN x:H a t t h e s i l i c o n K-edge C8-357

S.R. ELLIOTT, G.N. GREAVES, A.J. LOWE, L.F. GLADDEN and J.H.S. RENNIE.- EXAFS s t u d i e s o f p h o t o s t r u c t u r a l changes i n c h a l c o g e n i d e g l a s s e s C8-363

A. MARBEUF, F. KAROUTA, H. DEXPERT, P. LAGARDE and A. JOULLIE.-EXAFS s t u d y o f a q u i t e r e l a x e d z i n c - b l e n d e l a t t i c e : t h e GaAs S b ^ a l l o y C8-369

A. FILIPPONI, D. DELLA SALA, F. EVANGELISTI, A. BALERNA and S. MOBILIO.- S t r u c t u r a l p r o p e r t i e s o f a - S i and a-Si:H by EXAFS C8-375

A. MENELLE, A.M. FLANK, P. LAGARDE and R. BELLISSENT.- EXAFS s t u d y o f c - S i , a - Si and a-Si:H C8-379

X X I I

C. LAFFON, A.M. FLANK and P. LAGARDE.- S t r u c t u r a l EXAFS s t u d y o f c o m p o s i t e m a t e r i a l s o f t h e SiC t y p e C8-383

C.Y. YANG, J.M. LEE, M.A. PAESLER and D.E. SAYERS.- EXAFS s t u d i e s o f t h e r m o s t r u c t u r a l and p h o t o s t r u c t u r a l changes o f v a p o r - d e p o s i t e d amorphous As 2 S 3 f i l m s C8-387

C. Y. YANG, M.A. PAESLER and D.E. SAYERS.- A n a l y s i s o f bond s t r e n g t h s o f a r s e n i c and a r s e n i c c h a l c o g e n compounds u s i n g t h e t e m p e r a t u r e dependence o f t h e EXAFS C8-391

A.T. STEEL, A. P. FIRTH, A.E. OWEN, P. EWEN and G.N. GREAVES.-S i l v e r i n p h o t o d o p e d a r s e n i c s u l f i d e f i l m s : an EXAFS s t u d y C8-395

S.R. ELLIOTT and A.T. STEEL.- An EXAFS s t u d y o f B i d o p i n g i n c h a l c o g e n i d e g l a s s e s C8-399

Ν. MOTTA, A. BALZAROTTI and P. LETARDI.- L o c a l s t r u c t u r e and the r m o d y n a m i c s o f I I - V I and I I I - V s e m i c o n d u c t o r s by EXAFS C8-403

G. STEGEMANN and B. LENGELER.- C r y s t a l l i z a t i o n o f amorphous germanium i n v e s t i g a t e d by X-ray a b s o r p t i o n s p e c t r o s c o p y . . . C8-407

Ph. SAINCTAVIT, G. CALAS, J. PETIAU, R. KARNATAK, J.M. ESTEVA and G.E. BROWN, J r . - E l e c t r o n i c s t r u c t u r e f r o m X-ray K-edges i n ZnS:Fe and CuFeS 2 C8-411

E. DARTYGE, A. FONTAINE, A. JUCHA, G. TOURILLON, J.F. PERAY, R. JOUBARD and P. ALNOT.- I n v e s t i g a t i o n o f b u r r i e d i n t e r ­f a c e ( S i 3 N 4 / G a As) by EXAFS i n t o t a l r e f l e c t i o n and d i s ­p e r s i v e mode · C8-415

S. BENAZETH, M.H. TUILIER, H. DEXPERT, Μ. GUITTARD and D. CARRE.- C h a l c o g e n i d e and o x y c h a l c o g e n i d e g l a s s e s : e v o l u t i o n o f t h e g a l l i u m s u r r o u n d i n g w i t h t h e oxygen c o n t e n t C8-419

Η. OYANAGI, Y. TAKEDA, T. MATSUSHITA, T. ISHIGURO and A. SASAKI.- L o c a l s t r u c t u r e i n InGaAsP q u a t e r n a r y a l l o y s . . C8-423

S. GUITA, Ε. BELIN, C. SENEMAUD, D. UDRON, A. GHEORGHIU and M.L. THEYE.- I n v e s t i g a t i o n o f t h e L near-edge s t r u c t u r e i n c r y s t a l l i n e and amorphous GaAs C8-427

G. ANTONIOLI, S. B I N I , P.P. LOTTICI and C. RAZZETTI.- The l o c a l s t r u c t u r e i n t h e m i x e d c h a l c o p y r i t e C u G a x Ι η χ _ χ S e 2 . . . C8-431

SURFACES

P.H. CITRIN.- An o v e r v i e w o f SEXAFS d u r i n g t h e p a s t decade.... C8-437

U. DOBLER, L. WENZEL, D. ARVANITIS and K. BABERSCHKE.- S u r f a c e e x t e n d e d X - r a y a b s o r p t i o n f i n e s t r u c t u r e s t u d y on ( 2 x 1 ) oxygen on N i ( l l O ) C8-473

D. CHANDESRIS.- Ther m a l d i s o r d e r o f s u r f a c e atoms s t u d i e d by s u r f a c e EXAFS C8-479

X X I I I

M.D. CRAPPER, C.E. RILEY and D.P. WOODRUFF.- The a d s o r p t i o n s i t e o f f o r m a t e (HCOO) on copper s u r f a c e s C8-487

Μ. BADER, J. HAASE, K.-H. FRANK, C. OCAL and A. PUSCHMANN.-Near-edge X-ray a b s o r p t i o n f i n e - s t r u c t u r e s t u d i e s o f r i n g m o l e c u l e s a d s o r b e d on s i n g l e c r y s t a l s u r f a c e s C8-491

J.C. WOICIK, R.S. LIST, B.B. PATE and P. PIANETTA.- The s i l i c o n / g e r m a n i u m ( 1 1 1 ) i n t e r f a c e : t h e o n s e t o f e p i t a x y . . . C8-497

Τ. OHTA, Y. KITAJIMA, P.M. STEFAN, M.L. SHEK STEFAN, N. KOSUGI and H. KURODA.- S u r f a c e EXAFS and XANES s t u d i e s o f S/Ni(110) and S / N i ( l l l ) C8-503

G.M. LAMBLE, D.J. HOLMES, D.A. KING and D. NORMAN.- Coverage dependence o f a d s o r b a t e - s u b s t r a t e bond l e n g t h s ; c h l o r i n e and caesium ad s o r b e d on s i l v e r s i n g l e c r y s t a l s C8-509

I . DAVOLI, M. TOMELLINI and M. FANFONI.- S u r f a c e N i o x i d e s t u d i e d by oxygen K-XANES C8-517

G. ROSSI, D. CHANDESRIS, P. ROUBIN and J. LECANTE.- The g r o w t h o f t h e P t / S i ( 1 1 1 ) 7 x 7 i n t e r f a c e s as p r o b e d by

C8-521

D. NORMAN, C.H. RICHARDSON, D.R. WARBURTON, G. THORNTON, R. McGRATH and F. SETTE.- A z i m u t h a l l y - d e p e n d e n t X - r a y ab­s o r p t i o n n e a r edge s t r u c t u r e f o r s u l p h u r a d s o r b e d on n i c k e l ( H O ) C8-525

D. NORMAN, R.A. TUCK, H.B. SKINNER, P.J. WADSWORTH, Τ.Μ. GARDINER, I.W. OWEN, C.H. RICHARDSON and G. THORNTON.-S u r f a c e e x t e n d e d X-ray a b s o r p t i o n f i n e s t r u c t u r e a p p l i e d t o t h e p o l y c r y s t a l l i n e s u r f a c e s o f r e a l t h e r m i o n i c c a t h o d e s . . C8-529

M.D. CRAPPER, C.E. RILEY, P.J.J. SWEENEY, C.F. McCONVILLE, D.P. WOODRUFF and R.G. JONES.- The s t r u c t u r e o f t h e C u ( l l l ) (\Γ§ χ \J~3)R30°-C1 s u r f a c e : a combined SEXAFS and p h o t o -e l e c t r o n d i f f r a c t i o n s t u d y C8-533

F. MILA and C. NOGUERA.- Theory o f s u r f a c e e l e c t r o n e n e r g y l o s s f i n e s t r u c t u r e (S.E.E.L.F.S.) s p e c t r o s c o p y : r e l a t i o n s h i p t o EXAFS and p e r s p e c t i v e s C8-539

Volume 2

COORDINATION CHEMISTRY

R.F. PETTIFER, D.L. FOULIS and C. HERMES.- M u l t i p l e s c a t t e r i n g c a l c u l a t i o n s f o r b i o l o g i c a l c a t a l y s t s C8-545

G. TOURILLON, E. DARTYGE, A. FONTAINE, A. JUCHA and C. ANDRIEUX.- E l e c t r o n i c and s t r u c t u r a l m o d i f i c a t i o n s o f p o l y s e l e n o p h e n e d u r i n g e l e c t r o c h e m i c a l d o p i n g p r o c e s s ob­s e r v e d i n s i t u by d i s p e r s i v e X-ray a b s o r p t i o n s p e c t r o s c o p y C8-551

XXIV

S. SAIGO, Η. OYANAGI, Τ. MATSUSHITA, Η. HASHIMOTO, Ν. YOSHIDA, Μ. FUJIMOTO and Τ. NAGAMURA.- S t o p p e d - f l o w X - r a y a b s o r p t i o n s p e c t r o s c o p y i n d i s p e r s i v e mode C8-555

C. CARTIER, P. THUERY, M. VERDAGUER, J. ZAREMBOWITCH and A. MICHALOWICZ.- F i r s t c o o r d i n a t i o n s p h e r e and s p i n - s t a t e i n s p i n c r o s s - o v e r i r o n and c o b a l t complexes C8-563

J. HORMES, U. KUETGENS and I . RUPPERT.- Double e x c i t a t i o n i n t h e Κ - s h e l l a b s o r p t i o n s p e c t r u m o f s u l p h u r i n H 2S and D 2S C8-569

A. P. HITCHCOCK.- Near edge c o r e e x c i t a t i o n s p e c t r a o f complex m o l e c u l e s C8-575

G. TOURILLON, A. FONTAINE, M. SAGURTON, N.R. GARRETT and G. WILLIAMS.- E l e c t r o n i c s t r u c t u r e and o r i e n t a t i o n o f p y r r o l e , Ν m e t h y l p y r r o l e , t h i o p h e n e , 3 m e t h y l t h i o p h e n e and t h e i r p o l y m e r s on P t : a NEXAFS s t u d y C8-579

B. X. YANG, J. KIRZ and T.K. SHAM.- Oxygen K-edge a b s o r p t i o n s p e c t r a o f s m a l l m o l e c u l e s i n t h e gas phase C8-585

N. BINSTED, S.L. COOK, J. EVANS, R.J. PRICE and G.N. GREAVES.-M u l t i p l e s c a t t e r i n g e f f e c t s i n t h e c o b a l t K-edge EXAFS o f m e t a l c a r b o n y l complexes C8-589

R.W. STRANGE, S.S. HASNAIN, N.J. BLACKBURN and P.F. KNOWLES.-M u l t i p l e s c a t t e r i n g i n t h e EXAFS o f i m i d a z o l e c o n t a i n i n g complexes C8-593

D. L. FOULIS, R.F. PETTIFER and C.R. NATOLI.- P r o g r e s s i n SCF-SW-Xalpha ab i n i t i o XANES c a l c u l a t i o n s f o r chromium h e x a c a r b o n y l based on g e n e r a l n o n - m u f f i n - t i n p o t e n t i a l s . . . C8-597

J.E. HARRIES, D.W.L. HUKINS and S.S. HASNAIN.- M u l t i p l e s c a t t e r i n g i n t h e EXAFS o f c a l c i u m p h o s p h a t e s C8-603

E. DARTYGE, A. FONTAINE, G. TOURILLON and A. JUCHA.- EXAFS i n d i s p e r s i v e mode, a new t o o l f o r s t u d y i n g i n s i t u k i n e t i c s : example o f e l e c t r o c h e m i c a l i n c l u s i o n o f c o p p e r s p e c i e s i n an o r g a n i c c o n d u c t o r C8-607

H. OYANAGI, M. TOKUMOTO, T. ISHIGURO, H. SHIRAKAWA, Ν. NEMOTO, T. MATSUSHITA and H. KURODA.- P o l a r i z e d EXAFS and near-edge s p e c t r a o f h a l o g e n - d o p e d p o l y a c e t y l e n e C8-615

M. NOMURA and T. YAMAGUCHI.- S o l u t e s t r u c t u r e o f c o p p e r ( I I ) a c e t a t e s o l u t i o n s i n l i q u i d and g l a s s y s t a t e . . . . C8-619

C. CARTIER, M. VERDAGUER, S. MENAGE, J . J . GIRERD, J.P. TUCHAGUES and B. MABAD.- XANES o f manganese c o o r d i ­n a t i o n complexes C8-623

J. GALY, T. VOGT, P. LECANTE, A. MOSSET and J. STRAHLE.- EXAFS and LAXS s t r u c t u r a l i n v e s t i g a t i o n s o f amorphous one-dimen­s i o n a l compounds (ML 3 ) c o (M=Mo, Ru ; L = SPh, SePh, p y r a -z o l a t e ) C8-627

M. LOOS, J. GOULON, J.M. BARBE and R. GUILARD.- S t r u c t u r a l c h a r a c t e r i z a t i o n o f b i m e t a l l i c p o r p h y r i n complexes u s i n g d i f f e r e n c e EXAFS s p e c t r o s c o p y C8-633

XXV

Μ.F. RUIZ-LOPEZ, D. RINALDI, C. ESSELIN, J. GOULON, J.L. PONCET and R. GUILARD.- R e l a t i v e e n e r g y d i a g r a m o f t h e l o w e s t u n o c c u p i e d m o l e c u l a r o r b i t a l s o f oxo-, t h i o -and s eleno-vanadium ( I V ) p o r p h y r i n s , as i n f e r r e d f r o m combined XANES and ESR d a t a C8-637

M. LOOS, P. FRIANT, I . ASCONE, J. GOULON, J.M. BARBE, A. COUTSOLELOS and R. GUILARD.- S t a c k e d o r b r i d g e s t a c k e d p o l y m e r i c s t r u c t u r e s o f m e t a l l o p o r p h y r i n s and p h t a l o -c y a n i n e s i n v e s t i g a t e d by d i f f e r e n c e EXAFS s p e c t r o s c o p y . . . . C8-641

A. DEJEAN, P. CHARPIN, G. FOLCHER, P. RIGNY, A. NAVAZA and G. TSOUCARIS.- E v i d e n c e o f t h e u r a n i u m I I I and u r a n y l c o m p l e x a t i o n by m a c r o c y c l e s f r o m EXAFS C8-645

Μ. VERDAGUER, C. CARTIER, M. MOMENTEAU, E. DARTYGE, A. FONTAINE, G. TOURILLON and A. MICHALOWICZ.- From i r o n ( I I ) t o i r o n ( I I I ) b a s k e t h a n d l e p o r p h y r i n s : s t a t i c and k i n e t i c s X-ray a b s o r p t i o n s t u d i e s C8-649

K.-H. FRANK, E.-E. KOCH and H.-W. BIESTER.- O b s e r v a t i o n o f i n s i t u f o r m a t i o n o f p h t h a l o c y a n i n e - b i s ( p y r i d i n e ) i r o n ( I I ) by X-ray a b s o r p t i o n s p e c t r o s c o p y C8-653

INORGANIC MATERIALS

G.E. BROWN, J r . , G.A. WAYCHUNAS, C.W. PONADER, W.E. JACKSON and D.A. McKEOWN.- EXAFS and NEXAFS s t u d i e s o f c a t i o n en­v i r o n m e n t s i n o x i d e g l a s s e s C8-661

P.D. BATTLE, C.R.A. CATLOW, A.V. CHADWICK, G.N. GREAVES and L.M. MORONEY.- EXAFS s t u d i e s o f f l u o r i t e o x i d e s C8-669

0. HANSKEPETITPIERRE, E.A. STERN and Y. YACOBY.- EXAFS mea­surements on p o t a s s i u m t a n t a l a t e n i o b a t e C8-675

N. ALBERDING, E.D. CROZIER, R. INGALLS and B. HOUSER.- Fo-cussed m u l t i p l e s c a t t e r i n g i n compressed Re0 3 C8-681

G.E. BROWN, J r . , G.A. WAYCHUNAS, J. STOHR and F. SETTE.- Near-edge s t r u c t u r e o f oxy g e n i n i n o r g a n i c o x i d e s : e f f e c t o f l o c a l geometry and c a t i o n t y p e C8-685

S. STIZZA, Μ. BENFATTO, A. BIANCONI, J. GARCIA, G. MANCINI and C.R. NATOLI.- Vanadium s i t e s t r u c t u r e i n V 2 0 5 g e l by p o l a r i z e d EXAFS and XANES C8-691

J.M. COMBES, A. MANCEAU and G. CALAS. - S t u d y o f t h e l o c a l s t r u c t u r e i n p o o r l y - o r d e r e d p r e c u r s o r s o f i r o n o x i - h y d r o -x i d e s C8-697

A. MANCEAU, S. LLORCA and G. CALAS.- S t r u c t u r a l c h e m i s t r y o f Mn, Co and N i i n some n a t u r a l manganese o x i d e s C8-703

B. POUMELLEC, J.F. MARUCCO and B. TOUZELIN.- XANES c o m p a r a t i v e s t u d y o f r u t i l e s o l i d s o l u t i o n s : ( T i , V ) 0 2 , ( T i , N b ) 0 2 and ( T i , T a ) 0 2 C8-709

A. DE ROY, J.P. BESSE e t P. BONDOT.- Etude EXAFS de N i ( 0 H ) 2

comme compose modele des phases de t y p e s Z n 2 C r ( 0 H ) 6 X . 2 H 2 0 ( X = a n i o n ) C8-713

XXVI

F. W. LYTLE, R.B. GREEGOR and I.D. RAISTRICK.- D e t e r m i n a t i o n o f s t r u c t u r e and v a l e n c e i n vanadium b r o n z e by X-ray ab­s o r p t i o n s p e c t r o s c o p y C8-719

L.M. MORONEY and D.E. SAYERS.- The d e f e c t s t r u c t u r e o f c a l c i a s t a b i l i s e d z i r c o n i a C8-725

P. BERTHET, J. BERTHON and A. REVCOLEVSCHI.- Study by EXAFS o f z i r c o n i u m e n v i r o n m e n t i n A 1 2 0 3 - Z r 0 2 m a t e r i a l p r e p a ­r e d f r o m m e t a l - a l k o x i d e s C8-729

H. BEUTHIEN, D.v. AHLFTEN, W. GIRNUS, A. TORKLER, W. GUNSSER and W. NIEMANN.- I n v e s t i g a t i o n o f t h e double-phase t r a n ­s i t i o n o f T m 3 F e 5 0 1 2 by EXAFS s p e c t r o s c o p y C8-733

Τ. OKAMATO, T. SUZUKI and N. MATSUI.- EXAFS and XANES s t u d y on s p i n e l s t r u c t u r e m a t e r i a l s and t h e i r a p p l i c a t i o n t o h u m i d i t y s e n s o r C8-737

M.H. TUILIER, M. DEVALETTE, N. KHACHANI, M. DEXPERT and P. LAGARDE.- S t u d y o f s m a l l d i s t o r s i o n s i n B i 1 2 M o 2 0 o x i d e s by s i m p l e EXAFS t r a n s m i s s i o n t e c h n i c s C8-741

D.J. JONES, J. ROZIERE, G.C. ALLEN and P.A. TEMPEST.- The ap­p l i c a t i o n o f EXAFS s p e c t r o s c o p y t o t h e s t r u c t u r a l d e t e r ­m i n a t i o n o f f l u o r i t e t y p e oxygen- excess u r a n i u m o x i d e s and o f m i x e d (U,Ce) o x i d e s C8-745

G. DALBA, P. FORNASINI, F. ROCCA and E. BURATTINI.- XANES i n f a s t i o n c o n d u c t i n g g l a s s e s A g I : A g 2 0 : B 2 0 3 C8-749

G. DALBA, P. FORNASINI, F. ROCCA, A. KRAJEWSKI, A. RAVAGLIOLI and E. BURATTINI.- XAS s t u d i e s on t h e r o l e o f t h e a l k a l i n e i o n i n a l e a d - g l a z e s y s t e m C8-753

H. KAGEYAMA, N. KAMI JO, M. NARUKAWA, F. MARUYAMA, Υ. NAKAO and K. TANIGUCHI.- EXAFS and XANES s t u d i e s on L a 1 _ x S r x C o 0 3

compounds ( x = 0 , 0. 2, 0. 5 ) C8-757

N. KAMI JO, H. KAGEYAMA, M. NARUKAWA, F. MARUYAMA, Y. NAKAO, K. TANIGUCHI and H. MAEDA.- EXAFS and XANES s t u d y on r a r e -e a r t h c h r o m i t e s o f Gd x . x S r x C r 0 3 ( x = 0 , 0. 2, 0. 5 ) C8-761

M. LENGLET, R. GUILLAMET, A. D'HUYSSER, J. DURR and C.K. JORGENSEN.- Fe, N i c o o r d i n a t i o n and o x i d a t i o n s t a t e s i n c h r o m i t e s and c o b a l t i t e s by XPS and XANES C8-765

M.H. TUILIER and B. BUFFAT.- I n f l u e n c e o f o x i d a t i o n degree and symmetry on t h e s i t e on K - a b s o r p t i o n s p e c t r a o f s i x co­o r d i n a t e d i r o n and c o b a l t i n o x i d e s C8-771

S. BENAZETH, M. DANOT, P. COLOMBET, H. DEXPERT and P. LAGARDE.-Evide n c e f o r s h o r t C u ( I ) - C u ( I ) d i s t a n c e s i n co p p e r - e x c e s s s p i n e l s f r o m EXAFS C8-777

F. STUDER and A. LE BAIL.- EXAFS o f mixed v a l e n c e i r o n p o t a s s i u m p h o s p h a t e g l a s s e s C8-781

G. N. GREAVES, S.J. GURMAN and R.N. JENKINS.- An EXAFS s t u d y o f i r o n - l e a d p y r o p h o s p h a t e g l a s s C8-787

B. BOULARD, A. LE BAIL, J. P. LAVAL and J. JACOBONI. - L o c a l

XXVII

environment of Zr i n baryum f l u o r o z i r c o n a t e g l a s s e s : the EXAFS p o i n t of view C8-791

T. MURATA and S. EMURA.- EXAFS study of r e l a x a t i o n of Cu* im­p u r i t i e s i n a l k a l i h a l i d e s C8-795

J . F . JAL, J . DUPUY and A. SADOC- S t r u c t u r a l s t u d i e s of t h e l i q u i d Rb-RbBr systems by XANES C8-799

A. YOSHIASA, K. KOTO, S. EMURA and F. ΚANAMARU.- L o c a l s t r u c ­t u r e of the A g B r 1 _ x I x r o c k - s a l t type s o l i d - s o l u t i o n C8-803

P. DREIER and P. RABE.- EXAFS-study of the Z n 2 + c o o r d i n a t i o n i n aqueous h a l i d e s o l u t i o n s C8-809

G. CALAS, J . PETIAU and A. MANCEAU.- X-ray a b s o r p t i o n s p e c t r o ­scopy of g e o l o g i c a l m a t e r i a l s C8-813

G.N. GREAVES.- C o r r o s i o n s t u d i e s of g l a s s u s i n g c o n v e n t i o n a l and g l a n c i n g angle EXAFS C8-819

S.M. HEALD, J.M. TRANQUADA and H. CHEN.- I n t e r f a c e EXAFS u s i n g g l a n c i n g a n g l e s C8-825

D. BONNIN.- X-ray a b s o r p t i o n i n l a m e l l a r compounds C8-831

N. BINSTED, G.N. GREAVES and C.M.B. HENDERSON.- Fe K-edge X-ray a b s o r p t i o n s p e c t r o s c o p y of s i l i c a t e m i n e r a l s and g l a s s e s C8-837

G.A. WAYCHUNAS.- Examination of T i XANES s p e c t r a of m i n e r a l s and s o l i d s : e f f e c t s of s i t e geometry on s p e c t r a l f e a t u r e s C8-841

G.A. WAYCHUNAS, W.A. DOLLASE and C R . ROSS.- D e t e r m i n a t i o n of s h o r t range order (SRO) parameters from EXAFS p a i r d i s ­t r i b u t i o n f u n c t i o n s of oxide and s i l i c a t e s o l i d s o l u t i o n s . C8-845

D. PETIΤ-MAIRE, J . PETIAU, G. CALAS and N. JACQUET-FRANCILLON.-L o c a l s t r u c t u r e around a c t i n i d e s i n b o r o s i l i c a t e g l a s s e s . . C8-849

G.N. GREAVES, X.L. JIANG, R.N. JENKINS, E. HOLZENKAMPFER and S. KALBITZER.- The l o c a l s t r u c t u r e of a-SiOx:H f i l m s C8-853

A.J. FORTY, M. KERKAR, J . ROBINSON, S.M. EL-MASHRI and E.N. FARRABAUGH.- A s t r u c t u r a l i n v e s t i g a t i o n of some eva­porated S i O x f i l m s C8-857

D. JIANG, N. ALBERDING, A.J. SEARY and E.D. CROZIER.- A r e ­f l e c t i v i t y and EXAFS study of l a y e r e d s t r u c t u r e s C8-861

D. BONNIN, J . BOUAT, P. KAISER, C. FRETIGNY and F. BEGUIN.-Bond angle d e t e r m i n a t i o n by angular EXAFS st u d y and Debye-Wa l l e r a n i s o t r o p y i n 2D g r a p h i t e i n t e r c a l a t i o n compounds.. C8-865

C. FRETIGNY, D. BONNIN and R. CORTES.- P o l a r i z a t i o n e f f e c t s i n XANES of l a y e r e d m a t e r i a l s : a l k a l i - g r a p h i t e i n t e r c a l a t i o n compounds study C8-869

Υ. MATHEY, H. MERCIER and A. MICHALOWICZ.- EXAFS s t u d i e s of d i s o r d e r i n c r y s t a l l i n e l a m e l l a r compounds of the MPS3

f a m i l l y C8-875

N.T. BARRETT, G.M. ANTONINI, G.N. GREAVES, F.R. THORNLEY and

X X V I I I

A. MANARA.- G r a z i n g i n c i d e n c e f l u o r e s c e n c e EXAFS and near edge s p e c t r o s c o p y f o r corr o d e d g l a s s s u r f a c e s C8-879

F. R. THORNLEY, G.M. ANTONINI, G.N. GREAVES and N.T. BARRETT.-Depth c o n t r o l l e d EXAFS and near edge s p e c t r o s c o p y t o study s u r f a c e l a y e r s t r u c t u r e C8-883

J.M. MARTIN, M. BELIN and J . L . MANSOT.- EXAFS of c a l c i u m i n overbased m i c e l l e s C8-887

G. LOUPIAS, J . CHOMILLIER, J . TARBES, I . ASCONE, J . GOULON, D. GUERARD and N. ELALEM.- P o l a r i z a t i o n - d e p e n d e n t XANES of potassium h y d r i d e and potassium i n t e r c a l a t e d g r a p h i t e . . C8-891

J . P. I T I E , M. JEAN-LOUIS, E. DARTYGE, A. FONTAINE and A. JUCHA.- High p r e s s u r e XAS on bromine i n the d i s p e r s i v e mode C8-897

G.N. GREAVES, P.J. HALFPENNY, G.M. LAMBLE and K.J. ROBERTS.-The s t r u c t u r a l environment of Te dopants i n GaAs u s i n g EXAFS i n f l u o r e s c e n c e mode C8-901

F-ELECTRONS COMPOUNDS

G. KRILL.- X-ray a b s o r p t i o n s p e c t r o s c o p y ( L 3 edges, XANES, EXAFS) on 4 f m i x e d - v a l e n t compounds C8-907

A. KOTANI and T. JO.- Many body e f f e c t s i n X-ray a b s o r p t i o n edges of Ce compounds C8-915

0. GUNNARSSON and K. SCHONHAMMER.- Many body theory f o r spec­t r o s c o p i e s of Ce mixed v a l e n c e compounds C8-923

W. NIEMANN, W. MALZFELDT, P. RABE and M. LUBCKE. - X-ray ab­s o r p t i o n s t u d i e s o f mixed-valent r a r e e a r t h c l u s t e r s C8-931

J.M. TRANQUADA, S.M. HEALD, M.A. PICK, Z. FISK and J . L . SMITH.-L a t t i c e dynamics of the heavy fermion compound νΒθλ3 C8-937

G. KALKOWSKI, G. KAINDL, W.D. BREWER and W. KRONE.- X-ray ab­s o r p t i o n on uranium systems a t v a r i o u s t h r e s h o l d s C8-943

J . PETIAU, G. CALAS, D. PETIΤ-MAIRE, A. BIANCONI, M. BENFATTO and A. MARCELLI.- L o c a l i z a t i o n of 5f s t a t e s i n v a r i o u s uranium and thorium o x i d e s and g l a s s e s C8-949

J.M. ESTEVA, R.C. KARNATAK, H. DEXPERT, Μ. GASGNIER, P.E. CARO and L. ALBERT.- Nature of 4f e l e c t r o n s i n Tb o x i d e s by X-ray a b s o r p t i o n s p e c t r o s c o p y C8-955

E. BEAUREPAIRE, F. LE NORMAND and G. KRILL.- Core-hole s c r e e n i n g i n l i g h t r a r e - e a r t h i n s u l a t i n g compounds C8-961

N. WETTA, G. KRILL, P. HAEN, F. LAPIERRE, M.F. RAVET, C. GODART and F. HOLTZBERG.- Atomic r e l a x a t i o n i n mixed-v a l e n t systems deduced from EXAFS spect r o s c o p y C8-965

E. BEAUREPAIRE, J.P. KAPPLER, G. KRILL and F. GAUTIER. - Use of L j j j XANES f o r t h e d e t e r m i n a t i o n of atomic r e l a x a t i o n i n mixed v a l e n t r a r e e a r t h systems C8-971

XXIX

K.R. BAUCHSPIESS, E.D. CROZIER and R. INGALLS.- H i g h p r e s s u r e s t u d i e s o f SmSe a t 77 Κ C8-975

G. WORTMANN, Β. PERSCHEID and W. KRONE.- V a l e n c e d e t e r m i n a t i o n i n EuM-X, compounds : L T _ T - e d g e v e r s u s Mössbauer i s o m e r s h i f t . . . . C8-979

SUJATA PATIL, B.D. ΡADALIΑ, R. NAGARAJAN, L.C. GUPTA and R. VIJAYARAGHAVAN.- S u b s t i t u t i o n e f f e c t s on t h e m i x e d v a l e n c e b e h a v i o u r o f Eu i n E u C u 2 S i 2 C8-983

E. BEAUREPAIRE, J.P. KAPPLER, P. LEHMANN, G. KRILL and C. GODART.- H i g h e n e r g y s p e c t r o s c o p y i n v e s t i g a t i o n o f some t e r n a r y Ce systems C8-987

D. MALTERRE, A. SIA R I , J. DURAND, G. KRILL and G. MARCHAL.-X-ray a b s o r p t i o n s p e c t r o s c o p y on amorphous m i x e d - v a l e n t a l l o y s C8-991

G. VAN DER LAAN, B.T. THOLE, J. ZAANEN, G.A. SAWATZKY, J.C. FUGGLE, R.C. KARNATAK and J.M. ESTEVA.- M u l t i p l e t e f f e c t s i n n e a r edge XAS f o r g r o u n d s t a t e s t u d i e s C8-997

METALS

A. SADOC- The EXAFS o f q u a s i c r y s t a l s C8-1003

A. BALERNA and S. MOBILIO.- Dynamical p r o p e r t i e s o f Au m e t a l and c l u s t e r s f r o m EXAFS C8-1009

B. LENGELER.- I n t e r a c t i o n o f hydrogen w i t h i m p u r i t i e s i n d i l u t e p a l l a d i u m a l l o y s C8-1015

P. KIZLER, E. HERTLEIN, P. VARGAS and S. STEEB.- X-ray ab­s o r p t i o n measurements a t t h e b o r o n K-edge w i t h amorphous i r o n - and n i c k e l - b o r o n a l l o y s C8-1019

YANJUN MA and E.A. STERN.- EXAFS s t u d i e s o f AlM n S i and AIMn p e r i o d i c and a p e r i o d i c a l l o y s C8-1025

J.B. BOYCE, F.G. BRIDGES and J.J. HAUSER.- L o c a l s t r u c t u r e o f i c o s a h e d r a l and amorphous Al-Mn a l l o y s C8-1029

M. BESSIERE, E. DARTYGE and S. LEFEBVRE.- S t u d y o f s h o r t r a n g e o r d e r i n Au 3 Cu by EXAFS C8-1033

J . I . BUDNICK, M. CHOI, G.H. HAYES, D.M. PEASE, Z. TAN, E. KLEIN and B. ILLERHAUS.- D i f f e r e n c e i n Fe atom e n v i r o n m e n t s between CuFe ( 2 % Fe) and CuAuFe ( 1 and 3% Fe) a l l o y s C8-1037

0. YAMADA, H. MARUYAMA, K. SHIRAI and H. MAEDA.- L o c a l s t r u c ­t u r a l change o f p r e m a r t e n s i t i c t r a n s f o r m a t i o n i n Fe-Pt i n v a r a l l o y s C8-1041

T. BOLZE and J. PEISL.- EXAFS s t u d y on r a d i a t i o n i n d u c e d de­f e c t s C8-1045

T.J. VAN NETTEN, Κ. STAPEL and L. NIESEN.- L o c a l l a t t i c e r e ­l a x a t i o n a r o u n d 5 sp i m p u r i t i e s i n i r o n , n i c k e l and s i ­l i c o n C8-1049

XXX

J . I . BUDNICK, D.M. PEASE, M.H. CHOI, Z. TAN, G. HAYES, F. NAMAVAR and H.C. HAYDEN.- K r y p t o n XANES s t u d i e s i n i m ­p l a n t e d s y s tems C8-1053

L. ALAGNA, D. FIORANI, T. PROSPERI and J.L. DORMANN.- EXAFS s t u d i e s o f m e t a l - s u p p o r t i n t e r a c t i o n s v s c l u s t e r f o r m a t i o n i n i r o n p a r t i c l e s d i s p e r s e d i n amorphous a l u m i n a C8-1057

S.M. HEALD, J.M. TRANQUADA, B.M. CLEMENS and J. P. STEC- EXAFS s t u d y o f c o p p e r - h a f n i u m m u l t i l a y e r s C8-1061

C. BROUDER, G. KRILL, E. DARTYGE, A. FONTAINE, G. MARCHAL and P. GUILMIN.- EXAFS s t u d y o f a m o r p h i z a t i o n by s o l i d s t a t e r e a c t i o n i n Co/Sn m u l t i l a y e r s . * C8-1065

A. SADOC- EXAFS i n v e s t i g a t i o n o f an amorphous N i 6 4 Z r 3 6 a l l o y . Comparison w i t h n e u t r o n d i f f r a c t i o n i n f o r m a t i o n s C8-1069

T . I . MORRISON, M.B. BRODSKY and N.J. ZALUZEC- E l e c t r o n e n e r g y l o s s s p e c t r o s c o p y : p r o b e o f d-band occupancy i n amorphous m a g n e t i c a l l o y s C8-1073

A.J. FORTY, Μ. KERKAR, J. ROBINSON and M. WARD.- An EXAFS i n ­v e s t i g a t i o n o f t h e s t r u c t u r e o f t h e o x i d e f i l m s f o r m e d by t h e aqueous c o r r o s i o n o f i r o n - c h r o m i u m a l l o y s C8-1077

A. P. HITCHCOCK, J.D. GARRETT and T. TYLISZCZAK.- O r i e n t a t i o n and t e m p e r a t u r e depedence o f t h e Cd K - s h e l l EXAFS o f s i n g l e c r y s t a l Cd m e t a l : f i r s t EXAFS o b s e r v a t i o n o f R2... C8-1081

E. DARTYGE and A. SADOC- A n i s o t r o p i c t h e r m a l e f f e c t on Cd s i n g l e c r y s t a l s C8-1085

B. LENGELER.- I n t e r n a l o x i d a t i o n o f i m p u r i t i e s i n p a l l a d i u m i n v e s t i g a t e d by X - r a y a b s o r p t i o n s p e c t r o s c o p y C8-1089

V. PAUL-BONCOUR, M. DIAF, A. PERCHERON-GUEGAN and J.C ACHARD.-XAS s t u d y o f R N i 2 h y d r i d e s C8-1093

T.K. SHAM.- L-edge XANES s t u d i e s o f charge r e d i s t r i b u t i o n upon compound f o r m a t i o n i n g o l d and n i c k e l m e t a l l i c com­pounds C8-1097

R. ZELLER, G. STEGEMANN and B. LENGELER.- Empty e l e c t r o n i c d e n s i t i e s o f s t a t e s f o r 3d row el e m e n t s i n i r o n , n i c k e l and c o p p e r C8-1101

J. MIMAULT, T. GIRARDEAU, C. MAI and A. FONTAINE.- EXAFS i n CuZn b r a s s a l l o y s d u r i n g m a r t e n s i t i c t r a n s f o r m a t i o n C8-1105

BIOLOGY

CD. GARNER.- The i m p a c t o f X-r a y a b s o r p t i o n s p e c t r o s c o p y on b i o l o g y C8-1111

V.K. YACHANDRA, R.D. GUILES, A. McDERMOTT, R.D. BRITT, J. COLE, S.L. DEXHEIMER, Κ. SAUER and Μ.P. KLEIN.- The s t a t e o f manganese i n t h e p h o t o s y n t h e t i c a p p a r a t u s d e t e r m i n e d by X-ray a b s o r p t i o n s p e c t r o s c o p y C8-1121

XXXI

S.S. HASNAIN, L. ALAGNA, N.J. BLACKBURN and R.W. STRANGE.-EXAFS and XANES o f s u p e r o x i d e d i s m u t a s e : a c o p p e r p r o t e i n C8-1129

J.Ε. PENNER-HAHN, Κ. SMITH EBLE, J.Η. DAWSON and K.O. HODGSON.- S t r u c t u r a l c h a r a c t e r i z a t i o n o f h i g h v a l e n t i n t e r m e d i a t e s i n h o r s e r a d i s h p e r o x i d a s e C8-1137

I . ASCONE, J. GOULON, A. BIANCONI, M. TEGONI and F. LABEYRIE.-A s t u d y o f c y t o c h r o m e c and c y t o c h r o m e b 2 c o r e i n t h e o x i ­d i z e d and r e d u c e d s t a t e s u s i n g EXAFS and XANES s p e c t r o ­s c o p i e s C8-1143

H. OYANAGI, T.IIZUKA, T. MATSUSHITA, S. SAIGO, R. MAKINO and Y. ISHIMURA.- H i g h - r e s o l u t i o n XANES s t u d y o f t h e r m a l s p i n e q u i l i b r i u m i n m y o g l o b i n C8-1147

LUNG-SHAN KAU, E.W. SVASTITS, Μ. SONO, J.Η. DAWSON and K.O. HODGSON.- EXAFS s t u d y o f a c t i v e i n t e r m e d i a t e s : heme enzymes and model compounds C8-1151

E.C. THEIL, D.E. SAYERS, C.Y. YANG, A. FONTAINE and E. DARTYGE.- The f o r m a t i o n , s t r u c t u r e and d i s s o l u t i o n o f t h e f e r r i t i n i r o n c o r e s t u d i e d by X- r a y a b s o r p t i o n s p e c t r o ­scopy C8-1155

J.M. ARBER, A.C. FLOOD, C D . GARNER, S.S. HASNAIN and B.E. SMITH.- X- r a y a b s o r p t i o n s p e c t r o s c o p y o f Cu-Mo-S and Fe-Mo-S systems o f b i o l o g i c a l r e l e v a n c e C8-1159

M. ZEPPEZAUER, C. HAAS, W. MARET, C. HERMES and R.F. PETTIFER.-EXAFS i n v e s t i g a t i o n o f t h e s t r u c t u r a l s i t e o f l i v e r a l c o h o l dehydrogenase C8-1165

M.C FEITERS, C. LITTLE and S.G. WALEY.- M e t a l c o o r d i n a t i o n i n z i n c enzymes.,. C8-1169

M.C FEITERS, S.S. HASNAIN, CM. GROENEVELD, G.W. CANTERS, J. VAN RUN, J. REEDIJK, S. DAHLIN and B. REINHAMMAR. -Changes i n t h e m e t a l c o o r d i n a t i o n s p h e r e o f a z u r i n and s t e l l a c y a n i n u n d e r i n f l u e n c e o f pH, o x i d a t i o n / r e d u c t i o n and m e t a l s u b s t i t u t i o n C8-1173

LUNG-SHAN KAU, J.Ε. PENNER-HAHN, E . I . SOLOMON and K.O. HODGSON.- Q u a n t i t a t i v e Cu X-ray a b s o r p t i o n edge s t u d i e s : o x i d a t i o n s t a t e and s i t e s t r u c t u r e d e t e r m i n a t i o n C8-1177

D.W.L. HUKINS, A.J. COX and J.E. HARRIES.- EXAFS c h a r a c t e r i ­s a t i o n o f p o o r l y c r y s t a l l i n e d e p o s i t s f r o m b i o l o g i c a l systems i n t h e p r e s e n c e o f h i g h l y c r y s t a l l i n e m i n e r a l C8-1181

D.W.L. HUKINS, J.E. HARRIES, S.S. HASNAIN and C. HOLT.- B i o ­l o g i c a l c a l c i f i c a t i o n : i n v e s t i g a t i o n by X - r a y a b s o r p t i o n s p e c t r o s c o p y C8-1185

P.F. LINDLEY, R.W. EVANS, R.C GARRATT and S.S. HASNAIN.- The i r o n b i n d i n g - s i t e s o f c h i c k e n o v o t r a n s f e r r i n C8-1189

I . BERTINI, S. MANGANI, L. MESSORI, S. MOBILIO and P.L. ORIOLI.- EXAFS i n v e s t i g a t i o n s o f a N - t e r m i n a l f r a g m e n t o f human t r a n s f e r r i n c o n t a i n i n g a s i n g l e i r o n b i n d i n g s i t e C8-1193

J.E. PENNER-HAHN, T.A. SMITH, B. HEDMAN, K.O. HODGSON and S. DONIACH.- P o l a r i z e d X-ray a b s o r p t i o n n e a r edge s t r u c t u r e C8-1197

XXXII

I . ASCONE, A. FONTAINE, M. BARTERI, A. BIANCONI and A. CONGIU-CASTELLANO.- pH dependent XANES o f c a r b o n y l -h e m o g l o b i n by f a s t d i s p e r s i v e s p e c t r o s c o p y C8-1201

R.A. ASATURIAN, Ts.M. AVAKIAN, N.V. ERSHOV, A.L. AGEEV and M.A. KOZLOV.- L o c a l s t r u c t u r e o f c o p p e r - a l b u m i n complexes : i n v e s t i g a t i o n s by EPR and EXAFS s p e c t r o s c o p y C8-1205

AUTHOR INDEX C8-1211

JOURNAL DE PHYSIQUE C o l l o q u e C8, supplement au n° 12, Tome 47, decembre 1986 C8-277

EXAFS STUDY OF NICKEL TETRACARBONYL ÄND Ni-CLUSTERS IN ZEOLITE Y ( 1

Τ. BEIN*-**, S.J. McLAIN* , G.D. STUCKY* , G. WOOLERY* * , D.E. SAYERS*** and K. MÖLLER""

* E . I . Dupont de Nemours and Company, Central Research and Development Department, Experimental Station, Wilmington, DE 19898, U.S.A. **Mobil Research and Development Corporation, Paulsboro Research Laboratory, Paulsboro, NJ 08066, U.S.A. ***Department of Physics, North Carolina State University, Raleigh, NC 27695, U.S.A. * Department of Chemical Engineering, University of Delaware, Newark, DE 19116, U.S.A.

ABSTRACT A d s o r p t i o n and thermal decomposition of IMi(CG)^ i n t h e cage system o f z e o l i t e Y have been s t u d i e d u i t h EXAFS, e l e c t r o n microscopy and IR s p e c t r o s c o p y , Ni(CO)^ i s adsorbed as an i n t a c t molecule i n both c a t i o n - f r e e z e o l i t e Y and NaY. Symmetry changes of the molecule i n NaY are assigned t o the f o r m a t i o n o f Na —OC-IMi b r i d g e s . Thermal treatment of the Ni(CQ)^/NaY adduct leads t o l o s s o f CO co n c o m i t a n t u i t h t h e f o r m a t i o n of a b i n o d a l f\)i phase. A major p a r t o f t h e forms c l u s t e r s u i t h d i a m e t e r between 0.5 and about 1.5 nm, i n a d d i t i o n t o l a r g e r c r y s t a l l i t e s (5-30 nm), s t i c k i n g a t the ou t e r s u r f a c e o f t h e z e o l i t e matrix., The i \ ] i - i \ l i s c a t t e r i n g amplitude i n d i c a t e s i n c r e a s i n g average p a r t i c l e s i z e u i t h i n c r e a s i n g temperature.

INTRODUCTION Thermal decomposition of supported Ni(CO), as a p r e c u r s o r f o r d i s p e r s e d (Mi c a t a l y s t s has been r e p o r t e d p r e v i o u s l y ( 1 - 3 ) , i n a d d i t i o n t o a l i m i t e d number o f a t t e m p t s t o anchor mixed N i ( C 0 ) n i _ m complexes d i r e c t l y on p a r t i a l l y h y d r o x y l a t e d o x i d e s u r f a c e s ( 4 ) . L i t t l e i s knoun r e g a r d i n g the i n t e r a c t i o n o f t h e complex u i t h t h e m a t r i x and f o r m a t i o n of the metal phase. I n an at t e m p t t o un d e r s t a n d t h e r e a c t i v i t y o f n i c k e l c a r b o n y l compounds i n the cage system of f a u j a s i t s s , ue have used a c o m b i n a t i o n o f EXAFS, X-ray a b s o r p t i o n near edge spectroscopy (XANES) and t r a n s m i s s i o n e l e c t r o n m icroscopy. The r e s u l t s are compared u i t h those o b t a i n e d u i t h IR s p e c t r o s c o p y .

EXPERIMENTAL M a t e r i a l s : Z e o l i t e Y from Strem Chemicals ( L i n d e LZ-Y52), u i t h t h e u n ^ t c e l l com­p o s i t i o n N a ^ A l O ^ ^ S i O p ) ̂ 7 xH^O, uas dehydrated a t 670 Κ under 10 t o r r f o r 12 hours ( h e a t i n g räie 2 R/mm) and handled under n i t r o g e n i n a dr y b o x . Dealuminated z e o l i t e Y! uas prepared a c c o r d i n g t o ( 5 ) and dehy d r a t e d i n a s i m i l a r p r o c e d u r e . Ni(CO)^ from A l f a uas used as r e c e i v e d . Vapor phase l o a d i n g : 0.5 g of dehydrated z e o l i t e uere ueighed i n t o a q u a r t z sample h o l d e r i n the drybox, i n t r o d u c e d i n t o a v e r t i c a l q u a r t z r e a c t o r and evacuated a t 10 t o r r f o r 30 min. N i ( C 0 ) ^ uas degassed a t t h e same vacuum l i n e u i t h 3 f r e e z e -pump-thau c y c l e s under l e u i n t e n s i t y l i g h t . A c a l c u l a t e d amount o f c a r b o n y l vapor uas a d m i t t e d t o the z e o l i t e and a l l o u e d t o e q u i l i b r a t e f o r 30 min. a t 295 K, f o l l o u e d by evacuation f o r 30 min. G r a v i m e t r i c and manometric c o n t r o l o f t h i s process r e v e a l e d t h a t the dosing t e c h n i q u e a l l o u s a p r e d i c t a b l e l o a d i n g o f t h e z e o l i t e u i t h v o l a t i l e compounds.

C o n t r i b u t i o n 4081

C8-278 JOURNAL DE PHYSIQUE

Thermal d e c o m p o s i t i o n : Samples o f t h e c a r b o n y l / z e o l i t e adduct (300 mg) were heated under vacuum, u i t h a r a t e o f 1 K/min, up t o 323, 373 and 673 Κ (samples VAC323, UAC373 and 1/AC673) and h e l d a t thes e t e m p e r a t u r e s f o r 2 hours and 12 hours (673 K ) . Methods: IR s p e c t r a uere t a k e n u i t h a N i c o l e t 5DXB FT-IR sp e c t r o m e t e r i n a Barnes c o n t r o l l e d atmosphere d i f f u s e r e f l e c t a n c e IR c e l l u i t h CaF p u i n d o u s . EXAFS experiments uere c a r r i e d o u t a t t h e X11-A beamline a t the N a t i o n a l Synchroton L i g h t Source u i t h a s t o r e d e l e c t r o n energy o f 2.5 Gel/ a t c u r r e n t s betueen UD and 1G0 mA. S p e c t r a o f samples, embec^ed i n p a r a f f i n e or sea l e d i n p o l y e t h y l e n e c e l l s , uere taken i n a deuar u i t h Kapton uindous a t ca. 100 K. The data uere analyzed a c c o r d i n g t o p u b l i s h e d procedures ( 6 ) . Background removal uas accomplished u^ing a c u b i c s p l i n e f u n c t i o n and t h e r e s u l t a n t EXAFS modulations uere ueighed by k and F o u r i e r t r a n s f o r m e d over a range o f 2 t o 16 K. Tr a n s m i s s i o n e l e c t r o n m i c r o g r a p h s o f t h e z e o l i t e s uere taken on a H i t a c h i HSOO i n s t r u m e n t from microtomed s e c t i o n s o f 7G t o 90 nm t h i c k n e s s . The samples uere embedded i n Epon 812 under e x c l u s i o n o f a i r .

RESULTS AND DISCUSSION 1. A d s o r p t i o n o f N i c k e l T e t r a c a r h o n y l i n F a u j a s i t e . Lue p r e s e n t here t h e f i r s t EXAFS s p e c t r a o f Ni(CO)^ adsorbed i n d i f f e r e n t f a u j a s i t e s . F i g . 1 compares both near edge s p e c t r a and t h e F o u r i e r t r a n s f o r m e d EXAFS modulations ( F t s ) o f Ni(CO)^ i n de a l u m i n a t e d Y' and NaY. The complete match of both edge spec­t r a and the F t s betueen t h e t u o samples i n d i c a t e s t h a t a d s o r p t i o n of Ni(CO)^ i n t o t h e d i f f e r e n t forms o f z e o l i t e Y lead s t o e s s e n t i a l l y i d e n t i c a l m etal c a r b o n y l s p e c i e s . No o x i d a t i o n o f t h e N i i s observed upon a d s o r p t i o n i n t o t h e z e o l i t e . Comparison o f these edges u i t h t h a t o f neat Ni(CO)^ as u e l l as comparison of the magnitude o f t h e s t r o n g o u t e r s h e l l s c a t t e r i n g due'to l i n e a r CO i n d i c a t e s l i t t l e d i s t o r t i o n o f t h e CO l i g a n d s . The IR C O - s t r e t c h i n g p a t t e r n o f Ni(CG), i n Y' resembles t h a t of t h e neat c a r b o n y l , uhereas i n NaY f o u r d i f f e r e n t bands appear a t 2120, 2065, 2030 and 2010 cm" . I f combined u i t h t h e EXAFS r e s u l t s , t h i s o b s e r v a t i o n can be understood i n terms o f symmetry changes due t o Na —OC-Ni i n t e r a c t i o n s i n NaY z e o l i t e u h i c h are absent i n Y'. Comparable i n t e r a c t i o n s a r e d i s c u s s e d f o r the a d s o r p t i o n o f metal c a r b o n y l s on alumina and f o r c a r b o n y l - i o n p a i r i n g ( 7 , 8 ) . 2. Thermal Decomposition o f N i c k e l T e t r a c a r b o n y l i n F a u j a s i t e . NaY loaded u i t h 2,0 molecu l e s o f t h e c a r b o n y l per supercage and heated up t o 323 Κ i n vacuo f o r 2 hours (VAC323) l o s e s u e i g h t c o r r e s p o n d i n g t o a c o o r d i n a t i v e l y u n s a t u r a t e d system u i t h CG/Ni = 1, accompanied by a c o l o r change from u h i t e t o dark grey. The c o r r e s p o n d i n g XANES of WAC323 i s compared u i t h t h e edge of NaY/Ni(C0)^/,-j i n F i g . 2a. A d r a m a t i c r e d u c t i o n i n the f i r s t a b s o r p t i o n - maximum i n d i c a t e s i n c r e a s e d o c c u p a t i o n o f banding o r b i t a l s as expected upon r e l e a s e of p i - a c c e p t o r l i g a n d s . These edge changes are i n d i c a t i v e of the f o r m a t i o n of m e t a l l i c N i , though some r e s i d u a l bound CO i s s t i l l observed. I f t h e sample i s evacuated a t 373 h f o r 2 hours (VAC373), complete l o s s of CO i s nou observed as evidenced by comparison of the edges t o t h a t of Ni f o i l . Continued h e a t i n g t o 673 Κ produces no f u r t h e r changes i n t h e edge r e g i o n . G r a v i m e t r i c s t u d i e s a l s o shou t h a t a l l c a r b o n y l l i g a n d s are desorbed a t 373 K. The F o u r i e r t r a n s f o r m o f sample 1/AC323 i s compared t o t h a t of 1/AC373 i n F i g . 2b. S l i g h t d i f f e r e n c e s i n o u t e r s h e l l a m p l i t u d e s are v i s i b l e i n a d d i t i o n t o a sma l l peak i n V/AC323 c o r r e s p o n d i n g t o t h e Ni-C d i s t a n c e found i n N i ( C 0 ) ^ ( F i g . 1 ) . T h i s peak i s t e n t a t i v e l y a s s i g n e d t o r e s i d u a l CO l i g a n d s uhich are o n l y removed upcn e v a c u a t i o n a t 373 K. The e l e c t r o n m i c r o g r a p h o f 1/AC323 ( F i g 3) shous o c t a h e d r a l Ni c r y s t a l l i t e s of 5 - 3 0 nm d i a m e t e r , s t i c k i n g a t t h e o u t e r s u r f a c e of t h e z e o l i t e m a t r i x . C o n t r i b u t i o n s o f t h e 3 r d and ktU N i - N i s h e l l i n the EXAFS Fts ( F i g . 2b) must be due t o t h e l a r g e p a r t i c l e s t h a t a r e d e t e c t e d i n the TEM. The f i r s t N i - N i s c a t t e r i n g a m p l i t u d e amounts t o o n l y 50% o f t h e b u l k v a l u e , and t h e upper l i m i t o f b u l k - l i k e p a r t i c l e s i n t h i s system i s t h e r e f o r e 50%. T h i s assumtion uould i m p l y atomic d i s ­p e r s i o n - most l i k e l y u i t h oxygen c o o r d i n a t i o n - of the remaining Ni f r a c t i o n . S i n c e no oxygen c o o r d i n a t i o n i s d e t e c t e d i n the F t s , a c o n s i s t e n t model i n v o l v e s a b i n o d a l N i phase u i t h a major s i z e f r a c t i o n a t about z e o l i t e supercage dimensions and a f r a c t i o n o f l a r g e ( 5 - 3 0 nm) c r y s t a l l i t e s s t i c k i n g a t the o u t e r surface of t h e z e o l i t e m a t r i x .

C8-279

R+<X(Ä) R+«(Ä)

F i g u r e 1 and 2. Κ edge s p e c t r a (A) and F o u r i e r t r a n s f o r m e d , k weighted EXAFS modulations ( B ) . 1. l\li(CQ)ι i n NaY (-) and dealuminated Y' ( — ) . 2A. Edges of NaY/Ni(CG), (2 per supercage) ( — ) and sample VAC323 ( - ) . 2B. F t s of samples VAC323 (-) and VAC373 ( — ) .

F i g u r e 3.

T r a n s m i s s i o n e l e c t r o n m i c r o g r a p h o f sample V/AC323.

C8-280 JOURNAL DE PHYSIQUE

Comparison o f t h e l a t e r s t a g e s o f t h e r m a l t r e a t m e n t (samples 1/AC373 and VAC673) r e v e a l s a s i g n i f i c a n t i n c r e a s e o f N i - N i neighbor p o p u l a t i o n s . T h i s i s i n d i c a t i v e of an a g g l o m e r a t i o n process as expected f o r e l e v a t e d t e m p e r a t u r e s .

EXAFS s t u d i e s c o n c e r n i n g t h e c h a r a c t e r i z a t i o n o f supported n i c k e l m e t a l p a r t i c l e s have been r e p o r t e d ( 9 , 1 0 ) . Hydrogen r e d u c t i o n o f ) / S i ( 0 H ) i + g e l s y i e l d e d

p a r t i c l e s u i t h d i a m e t e r s betueen 2 and 10 nm ( 9 ) , uhereas l a r g e r p a r t i c l e s were produced u s i n g a gas e v a p o r a t i o n t e c h n i q u e ( 1 0 ) . The magnitude of t h e EXAFS r a d i a l d i s t r i b u t i o n f u n c t i o n uas fo u n d t o decrease s u b s t a n t i a l l y u i t h d e c r e a s i n g average p a r t i c l e s i z e (10)· I t becomes c l e a r t h a t c a r e f u l d e c o m p o s i t i o n of Ni(CO)^ adsorbed i n z e o l i t e s p r o v i d e s a v a l u a b l e t e c h n i q u e f o r t h e p r e p a r a t i o n o f s m a l l n i c k e l p a r t i c l e s .

ACKNOWLEDGEMENTS The a u t h o r s would l i k e t o acknowledge t h e f o l l o u i n g people: Dr. Steve Heald, L a r r y F e r e r i a and Jack S c r o f a n i o f Brookhaven N a t i o n a l L a b o r a t o r y a s s i s t e d i n da t a c o l l e c t i o n . Dr. David C o r b i n o f DuPont prepared t he dealuminated Y' z e o l i t e , M i c h a e l Wan K a v e l a a r p r e p a r e d e l e c t r o n micrographs, and David Rathfuss of DuPont p r o v i d e d g e n e r a l t e c h n i c a l a s s i s t a n c e . Κ. M. i s g r a t e f u l f o r a g r a n t from Deutsche Fo r s c h u n g s g e m e i n s c h a f t . T h i s uork uas supported i n p a r t by DOE g r a n t DE-AS05 BOER 107^+2·

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