Comparative study of oxidation on Cu and Cu3Au surfaces with a hyperthermal O2 molecular beam

Dissociative adsorption of hyperthermal O2 molecules on Cu3Au(1 0 0) was investigated by X-ray photoemission spectroscopy in conjunction with a synchrotron light source. Comparing the O-uptake curve on Cu3Au to that on Cu, it was determined that the dissociative adsorption of O2 implies a higher activation barrier and therefore less reactivity due to the Au alloying. The low-energy electron-diffraction (LEED) pattern of a c(2 × 2) for the clean surface turned into a sharp (1 × 1) LEED pattern during oxidation by a hyperthermal O2 molecular beam, suggesting that O adsorption induces Cu-atom segregation on the surface.