Nature of Oxidation of the Au(111) Surface: Experimental and Theoretical Investigation

The Au(111) surface is the prototypical inert metal substrate, whose interaction with oxygen remains a controversial issue. Here, we study the effect of dosing temperature and coverage on the absorption of atomic oxygen on this surface, using ab initio molecular dynamics and high-resolution electron energy loss spectroscopy. Two vibrational peaks are observed experimentally at 380 and 580 cm −1 . The lower frequency peak is predominant at low oxygen coverages, while the higher frequency peak grows more pronounced with increasing oxygen coverage. Our simulations reproduce these results and show that oxygen chemisorbed on the surface is the primary species at low coverages or low surface temperatures. An oxide-like species, both on the surface and under the top layer of gold, becomes dominant at higher coverages or temperatures. These results elucidate the nature of oxidation of the Au(111) surface.