The Physical Character of the Au (001) Surface Reconstruction in the Presence of CO and O2

The interaction of carbon monoxide and oxygen on Au (001) single crystal facets has been investigated using synchrotron based surface x-ray diffraction and scattering techniques. Preliminary experiments confirm the quasi-hexagonal surface reconstruction can be influenced by exposure to CO and O, and indicate that oxidation may be present. Subsequent surface x-ray scattering experiments included a residual gas analyzer (RGA) with isotopic CO to tag the chemical species. Both CO (by itself) and O (dissociated from molecular $\mathrm{O}_2$ by the x-rays) are capable of lifting the hexagonal surface reconstruction resulting in a disordered bulk truncated surface. A wide range of pressures (1 mTorr - 10 Torr) and temperatures (300 K - 900 K) have been explored. We have also adapted a system of coupled partial differential equations to model the absorption kinetics and surface reconstructions.