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The adsorption of CO on Pd(100) studied by IR reflection absorption spectroscopy
A292 Surface Science 119 (1982) 71-78 North-Holland Publishing Company POTENTIALS
OF MEAN
Steven M. VALONE,
71
FORCE
FOR ADATOMS
Jimmie D. DOLL
ON SURFACES
a n d H. K e i t h M c D O W E L L *
Los Alamos Scientific Laboratory, University of California, Los Alamos, New Mexico 87545. USA
Received 1 February 1982 Differences between the adatom-adatom potential of mean force and the pair potential in the limit of low adatom density are illustrated through the Kirkwood equation for a two-component solid. The major difference which remains at all adatom densities arises from the adatom substrate contribution to the potential of mean force. A method designed to extract an estimate of the adatom-adatom pair potential from field ion microscopy data is suggested.
Surface Science 119 (1982) 79-94 North-Holland Publishing Company THE ADSORPTION ABSORPTION A. ORTEGA
79
OF CO ON Pd(100) STUDIED
BY IR REFLECTION
SPECTROSCOPY *, F . M . H O F F M A N
** a n d A . M . B R A D S H A W
Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-IO00 Berlin 33, Fed. Rep. of Germany Received 24 November 1981 ; accepted for publication 5 April 1982
High resolution vibrational spectra of the C - O stretching region have been measured for the system CO/Pd(100) at temperatures between 80 and 340 K. LEED and flash desorption studies enabled the absolute coverage for each spectrum to be determined. The C - O stretching frequency was found to shift linearly with coverage for the three adsorption temperatures 80, 200 and 300 K. At saturation coverage (8--0.8) the total shift is of the order of 100 cm i. Experiments with ~2CO/13CO mixtures showed that the contribution of vibrational coupling is ~ 35 cm-J the rest being due to a static, partly chemical, lateral interaction. The apparent commensurate-incommensurate transition at /9--0.5 has no significant influence on shift, width or intensity of the absorption band.
95
Surface Science I 19 (1982) 95-106 North-Holland Publishing Company P t t 0 N i g 0 ( l l l ) S I N G L E CRYSTAL ALLOY: D E T E R M I N A T I O N OF THE SURFACE COMPOSITION BY AES, XPS AND ISS J.C. B E R T O L I N I , IMELIK
J. M A S S A R D I E R ,
P. D E L I C H E R E ,
B. T A R D Y
a n d B.
lnstitut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, F-69626 Villeurbanne Cedex, France
Y. J U G N E T
* and Tran Minh DUC
lnstitut de Physique Nucl~aire (INePt), Universitb Claude Bernard Lyon L 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France
and
OF MEAN
Steven M. VALONE,
71
FORCE
FOR ADATOMS
Jimmie D. DOLL
ON SURFACES
a n d H. K e i t h M c D O W E L L *
Los Alamos Scientific Laboratory, University of California, Los Alamos, New Mexico 87545. USA
Received 1 February 1982 Differences between the adatom-adatom potential of mean force and the pair potential in the limit of low adatom density are illustrated through the Kirkwood equation for a two-component solid. The major difference which remains at all adatom densities arises from the adatom substrate contribution to the potential of mean force. A method designed to extract an estimate of the adatom-adatom pair potential from field ion microscopy data is suggested.
Surface Science 119 (1982) 79-94 North-Holland Publishing Company THE ADSORPTION ABSORPTION A. ORTEGA
79
OF CO ON Pd(100) STUDIED
BY IR REFLECTION
SPECTROSCOPY *, F . M . H O F F M A N
** a n d A . M . B R A D S H A W
Fritz-Haber-lnstitut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-IO00 Berlin 33, Fed. Rep. of Germany Received 24 November 1981 ; accepted for publication 5 April 1982
High resolution vibrational spectra of the C - O stretching region have been measured for the system CO/Pd(100) at temperatures between 80 and 340 K. LEED and flash desorption studies enabled the absolute coverage for each spectrum to be determined. The C - O stretching frequency was found to shift linearly with coverage for the three adsorption temperatures 80, 200 and 300 K. At saturation coverage (8--0.8) the total shift is of the order of 100 cm i. Experiments with ~2CO/13CO mixtures showed that the contribution of vibrational coupling is ~ 35 cm-J the rest being due to a static, partly chemical, lateral interaction. The apparent commensurate-incommensurate transition at /9--0.5 has no significant influence on shift, width or intensity of the absorption band.
95
Surface Science I 19 (1982) 95-106 North-Holland Publishing Company P t t 0 N i g 0 ( l l l ) S I N G L E CRYSTAL ALLOY: D E T E R M I N A T I O N OF THE SURFACE COMPOSITION BY AES, XPS AND ISS J.C. B E R T O L I N I , IMELIK
J. M A S S A R D I E R ,
P. D E L I C H E R E ,
B. T A R D Y
a n d B.
lnstitut de Recherches sur la Catalyse, CNRS, 2 Avenue Albert Einstein, F-69626 Villeurbanne Cedex, France
Y. J U G N E T
* and Tran Minh DUC
lnstitut de Physique Nucl~aire (INePt), Universitb Claude Bernard Lyon L 43 Boulevard du 11 Novembre 1918, F-69622 Villeurbanne Cedex, France
and