Translational energy induced reconstruction and absorption in the oxidation processes of Cu{111}

The oxidation processes of Cu {111} with thermal and hyperthermal O-2 were studied using high-resolution X-ray photoemission spectroscopy (XPS) in conjunction with a synchrotron radiation (SR) source. We measured O-uptake curves for thermal O-2 exposure and hyperthermal O-2 molecular beam (HOMB) irradiation on a Cu{111} surface at similar to 300 K. Under an O coverage (Theta) less than or equal to 0.4 ML, oxidation with HOMB irradiation caused reconstruction of the Cu{111} surface to a distorted Cu{100} (root2 x root2)R45degrees - O overlayer. The oxidation accompanied by reconstruction is more effective with HOMB irradiation than thermal O-2 exposure. Low-energy electron diffraction (LEED) observations and XPS measurements suggest that HOMB irradiation is useful for fabricating O-induced reconstructed surfaces, which are precursors to Cu2O. Further oxidation under Theta greater than or equal to 0.4 ML proceeds slowly when irradiating with 2.3-eV HOMB, while a prominent increase in Theta over 0.4 ML was not observed when irradiating with 0.6-eV HOMB. The incident O-2 energy can control the oxidation processes of Cu{111}. (C) 2004 Elsevier B.V. All rights reserved.