title: Dynamics of O2Chemisorption on a Flat Platinum Surface Probed by an Alignment-Controlled O2Beam.
abstract: O2adsorption on Pt surfaces is of great technological importance owing to its relevance to reactions for the purification of car exhaust gas and the oxygen reduction on fuel-cell electrodes. Although the O2/Pt(111) system has been investigated intensively, questions still remain concerning the origin of the low O2sticking probability and its unusual energy dependence. We herein clarify the alignment dependence of the initial sticking probability (S0) using the single spin-rotational state-selected [(J,M)=(2,2)] O2beam. The results indicate that, at low translational energy (E0) conditions, direct activated chemisorption occurs only when the O2axis is nearly parallel to the surface. At high energy conditions (E0>0.5 eV), however, S0for the parallel O2decreases with increasing E0while that of the perpendicular O2increases, accounting for the nearly energy-independent O2sticking probability determined previously by a non-state-resolved experiment.
authors.affiliation: International Center for Young Scientists, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Ueta
authors.affiliation: Surface Characterization Group, National Institute for Materials Science, 1-2-1 Sengen, Tsukuba, Ibaraki, 305-0047, Japan.
authors.forename: Mitsunori
authors.initials: M
authors.lastname: Kurahashi
keywords: adsorption; chemisorption; oxygen; platinum; surface chemistry