Surface oxidation dynamics on Ni(001) and Ni(111) as observed by synchrotron photoemission spectroscopy

Teraoka, Yuden; Iwai, Yutaro*; Inoue, Keisuke*; Yoshigoe, Akitaka ; Okada, Ryuta

In order to make clear oxidation dynamics of Ni(001) surface, oxygen uptake curves were observed at every translational kinetic energy of supersonic O molecular beam. The surface temperature was set at a room temperature and the clean surface was irradiated by a supersonic O molecular beam with a selected translational energy ranging from 0.3 eV to 2.3 eV. Adsorbed oxygen was detected by synchrotron photoemission spectroscopy. A plateau behavior, showing a two-dimensional oxide island growth, disappeared with increasing incident energy. The largest initial sticking probability was observed in backfilling oxidation. This implies that dissociative adsorption of O molecule takes place through a physically-adsorbed state in the low energy region. A plateau region from 0.5 eV to 1 eV in the initial sticking on the Ni(001) surface reveals that a potential barrier exists around 1 eV and there are some differences in tunneling effects.