Temperature dependence of Cu2O formation on Cu3Au(1Â 1Â 0) surface with energetic O2 molecular beams

We report a study of the surface temperature (Ts) dependence of oxidation on Cu3Au(1 1 0) induced by a hyperthermal O2 molecular beam (HOMB), using X-ray photoemission spectroscopy in conjunction with synchrotron radiation. From the Ts dependence of the O uptake curve, the direct dissociative adsorption process is dominant process in the oxidation at less than O coverage (Θ) of 0.2 monolayer (ML) for the 2.2 eV HOMB incidence. On the other hand, the oxidation, in particular, the Cu2O formation, depends on Ts at high Θ. The high Ts causes the efficient Cu segregation on the surface at high Θ, suggesting the dominant role of Cu migration in the Cu2O formation.