Translational energy induced oxidation of Ni(111) surface at room temperature by supersonic O molecular beam

Teraoka, Yuden; Inoue, Keisuke*; Jinno, Muneaki*; Okada, Ryuta; Yoshigoe, Akitaka 

The effects of O incident energy have been widely studied by soft X-ray photoemission spectroscopy with high brilliance and high energy-resolution synchrotron radiation. Real-time in-situ photoemission spectroscopy of chemical bonding states for the oxidized surface was conducted during SSMB irradiation. Oxygen uptake has been observed at various O incident energies. The first plateau was found to disappear and an oxygen content at saturation of 5.5 ML was observed for an incident energy of 2.3 eV. This is 1.8 times larger than that observed at a low energy region of 0.06 eV to 0.6 eV (3 ML). The initial sticking rate continued to increase as incident energy increased up to 1.0 eV, and a remarkable re-increase was observed in the region around 2.3 eV. The first increase is due to the activated dissociative adsorption of O molecules and the second increase around 2.3 eV implies that another potential energy barrier exists with a height larger than 2.3 eV.