Coadsorption-induced effects at surfaces: Thermal desorption spectroscopy and x-ray photoelectron spectroscopy study of oxygen compression by Au on Ru(001)

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA)

DOI:https://doi.org/10.1116/1.577465· OSTI ID:5694575

Malik, I J; Hrbek, J ^[1]

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1. Brookhaven National Laboratory, Chemistry Department, Upton, New York 11973 (US)

Coadsorption of gold on an oxygen saturated ruthenium surface causes dramatic changes in the energetics and kinetics of oxygen desorption and the selectivity of surface processes. The activation energy for desorption of oxygen ({ital E}{sub {ital A}}) is lowered, it is coverage independent, and the process is governed by first-order kinetics. The lower {ital E}{sub {ital A}} prevents oxygen bulk diffusion, which otherwise competes with desorption from a pure oxygen layer, thus leading to a twofold increase in the amount of desorbing oxygen. A complete analysis of desorption data yields {ital E}{sub {ital A}}=81{plus minus}4 kcal/mol, prefactor {nu}{sup (1)}=(4{plus minus}2){times}10{sup 14} s{sup {minus}1}, and reaction order {ital n}=0.94. There is no direct interaction between Au and O, as inferred from gold desorption and x-ray photoelectron spectroscopy data. We propose that changes in {ital E}{sub {ital A}}, {nu}, and {ital n} arise as three-dimensional gold islands compress the oxygen overlayer causing a local increase in oxygen coverage. Desorption of oxygen occurs before the onset of Au desorption and as oxygen leaves the Ru surface, gold adatoms spread over Ru keeping the local oxygen coverage constant.

• DOE Contract Number: AC02-76CH00016
• OSTI ID: 5694575
• Journal Information: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA), Journal Name: Journal of Vacuum Science and Technology, A (Vacuum, Surfaces and Films); (USA) Vol. 9:3; ISSN JVTAD; ISSN 0734-2101
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals & Alloys-- Physical Properties
ACTIVATION ENERGY
ADSORPTION
DESORPTION
ELECTRON SPECTROSCOPY
ELEMENTS
ENERGY
GOLD
METALS
NONMETALS
OXYGEN
PHOTOELECTRON SPECTROSCOPY
PLATINUM METALS
RUTHENIUM
SORPTION
SORPTIVE PROPERTIES
SPECTROSCOPY
SURFACE PROPERTIES
TRANSITION ELEMENTS