Adsorption of oxygen on Au(111) by exposure to ozone

N. Saliba, D. H. Parker, Bruce E. Koel

Research output: Contribution to journalArticle

278 Scopus citations

Abstract

Atomic oxygen coverages of up to 1.2 ML may be cleanly adsorbed on the Au(111) surface by exposure to O3 at 300 K. We have studied the adsorbed oxygen layer by AES, XPS, HREELS, LEED, work function measurements and TPD. A plot of the O(519 eV)/Au(239 eV) AES ratio versus coverage is nearly linear, but a small change in slope occurs at HO=0.9 ML. LEED observations show no ordered superlattice for the oxygen overlayer for any coverage studied. One-dimensional ordering of the adlayer occurs at low coverages, and disordering of the substrate occurs at higher coverages. Adsorption of 1.0 ML of oxygen on Au(111) increases the work function by +0.80 eV, indicating electron transfer from the Au substrate into an oxygen adlayer. The O(1s) peak in XPS has a binding energy of 530.1 eV, showing only a small (0.3 eV) shift to a higher binding energy with increasing oxygen coverage. No shift was detected for the Au 4f7/2 peak due to adsorption. All oxygen is removed by thermal desorption of O2 to leave a clean Au(111) surface after heating to 600 K. TPD spectra initially show an O2 desorption peak at 520 K at low HO and the peak shifts to higher temperatures for increasing oxygen coverages up to HO=0.22 ML. Above this coverage, the peak shifts very slightly to higher temperatures, resulting in a peak at 550 K at HO=1.2 ML. Analysis of the TPD data indicates that the desorption of O2 from Au(111) can be described by first-order kinetics with an activation energy for O2 desorption of 30 kcal mol-1 near saturation coverage. We estimate a value for the Au-O bond dissociation energy D(Au-O) to be ∼56 kcal mol-1.

Original languageEnglish (US)
Pages (from-to)270-282
Number of pages13
JournalSurface Science
Volume410
Issue number2-3
DOIs
StatePublished - Aug 1 1998

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Materials Chemistry

Keywords

  • Adatoms
  • Adsorption kinetics
  • Auger electron spectroscopy (AES)
  • Chemisorption
  • Compound formation
  • Gold
  • Low energy electron diffraction (LEED)
  • Low index single crystal surfaces
  • Oxidation
  • Oxygen
  • Ozone
  • Soft X-ray photoelectron spectroscopy

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