A408

most one monolayer of dissociatively adsorbed oxygen characterized by an O ls binding energy of 529.9 eV. The same silver foil has also been impregnated with a highly hydrated layer of KOH. This layer was subsequently calcined in a stream of oxygen gas at 0.1 MPa and at 570 K. The resulting surface phase showed a K 2p.~12 signal at 293.0 eV and a broad O ls signal which was composed of at least two peaks at about 531 and 529.6 eV. The peak areas gave constant dement K : O ratios of 1:2 up to 770 K. These XPS results were interpreted by a mixed oxyhydroxide

phase containing K and Ag.

Surface Science 146 t1984) 341 350 341 North-Holland, Amsterdam

A D S O R P T I O N - D E S O R P T I O N KINETICS OF CARBON M O N O X I D E ON Ru(0001) AND Ru(21122) SINGLE CRYSTAL SURFACES T a r o Y A M A D A a n d K e n z i T A M A R U *

Department of Chemistry, Faculty of Science, The Universi(v of Tokyo, Hongo, Bunkvo-ku, Tokyo I13, Japan

Received 10 April 1984; accepted for publication 18 June 1984

Adsorption-desorption kinetics of carbon monoxide on Ru(0001) and Ru(21122) single crystal surfaces was investigated by measuring the absolute adsorption rate and the absolute desorption rate while the adsorption was actually proceeding. The absolute adsorption rate was a non-linear function of the surface coverage of CO and showed similar behavior on both two surfaces. The absolute desorption rate included a term depending on the gas-phase pressure, likewise our previous works on Pd and Rh. This pressure-dependent part of the desorption rate increased with the temperature of the crystals with activation energies of 4.9 kcal tool- 1 for Ru(0001) and 6.1 kcal tool- i for Ru(21122).

Surface Science 146 (1984) 351-362 North-Holland, Amsterdam

PREPARATION A N D CHARACTERIZATION OF OPTO- ELECTROCHEMICAL A g / A I C O M P O S I T E ELECTRODES M. A B R A H A M *, J.P. R O L L A N D and A. T A D J E D D I N E **

Laboratoire d'Electrochimie lnterfaciale du CNRS, l Place Aristide Briand, F- 92195 Meudon Pal Cedex, France

a n d

G. S C H I F F M A C H E R

Laboratoire des Elements de Transitions dans les Solides ER 210, l Place Aristide Briand, F- 92195 Meudon Principal Cedex, France

Received 18 May 1984; accepted for publication 29 June 1984

351

We describe the preparation of a opto-electrochemical electrode designed for in-situ studies of the metal-electrolyte interface by optical excitation of surface plasmons up to the UV region. The samples are very thin Ag-layers evaporated onto AI films on quartz substrates under UHV conditions to avoid alumina formation. SIMS and transmission electron microscope measurements show the continuous epitaxial growth of the 5 nm Ag layers on the alumina free AI film. The stability of the system in air and in the electrolyte has been tested optically and electrochemically.