Photoemission study of the translational energy induced oxidation processes on Cu(111)

The oxidation processes of Cu(111) with a hyperthermal O2 molecular beam (HOMB) were studied using high-resolution x-ray photoemission spectroscopy in conjunction with a synchrotron radiation source. The O-uptake curves were precisely measured at ∼300 K when irradiating with 2.3 and 0.6 eV HOMB on a Cu(111) surface. A Langmuir-type adsorption model at an oxygen coverage (Θ)⩽0.4 ML describes the kinetics of dissociative adsorption in the HOMB incidence. On the other hand, further inefficient oxidation occurs even for the 2.3 eV HOMB irradiation at Θ⩾0.4 ML. A collision-induced absorption mechanism can interpret the slow oxidation process of Cu(111).