Coadsorption-induced effects at surfaces: Compression of a chemisorbed oxygen layer by gold on Ru(001)

Journal Article · Wed Mar 20 23:00:00 EST 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100159a066· OSTI ID:5543341

Malik, I J; Hrbek, J ^[1]

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1. Brookhaven National Lab., Upton, NY (United States)

An experimental study of the Au/O/Ru(001) system has shown that coadsorption of gold causes dramatic changes in the parameters of oxygen desorption and, consequently, in the selectivity of surface processes. E{sub A}, the activation energy for desorption of oxygen, is lowered, it is coverage independent, and desorption of oxygen is governed by approximately first-order kinetics. Lower E{sub A} prevents oxygen bulk diffusion, which otherwise competes with desorption from a pure oxygen layer, thus leading to a 2-fold increase in the amount of desorbing oxygen. A complete analysis of desorption data yields E{sub A} = 339 {plus minus} 17 kj/mol, prefactor {nu} = (4 {plus minus} 2) {times} 10{sup 14}s{sup {minus}1}, and reaction order n = 0.94 {plus minus} 0.03. Observed effects are not due to chemical interactions between Au and O, as inferred from TDS, AES, and XPS data. The authors propose that changes in E{sub A}, {nu}, and n arise as gold 3-D islands compress oxygen 2-D islands, keeping the local oxygen coverage higher than in a saturated pure oxygen overlayer. As oxygen leaves the Ru surface (before any significant Au desorption), gold adatoms spread over the liberated Ru surface, keeping oxygen compressed and local oxygen coverage constant.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5543341
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Journal Issue: 6 Vol. 95:6; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ACTIVATION ENERGY
ADSORPTION
ARRHENIUS EQUATION
AUGER ELECTRON SPECTROSCOPY
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
COMPRESSION
DESORPTION
DIFFUSION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
EQUATIONS
GOLD
KINETICS
METALS
MILLER INDICES
NONMETALS
OXYGEN
PLATINUM METALS
REACTION KINETICS
RUTHENIUM
SEPARATION PROCESSES
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
SURFACES
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0400-1000 K
TEMPERATURE RANGE 1000-4000 K
TRANSITION ELEMENTS
X-RAY SPECTROSCOPY