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

Abstract

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 ∼300 K. Under an O coverage ( Θ) ≤0.4 ML, oxidation with HOMB irradiation caused reconstruction of the Cu{111} surface to a distorted Cu{100} ( 2 × 2 )R45 °- 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 Cu 2O. Further oxidation under Θ≥0.4 ML proceeds slowly when irradiating with 2.3-eV HOMB, while a prominent increase in Θ ̇ 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}.