Adsorption State and Molecular Orientation of Ammonia on ZnO(10(1-bar)0) Studied by Photoelectron Spectroscopy and near-Edge X-ray Absorption Fine Structure Spectroscopy

摘要

The adsorption state of ammonia (NH_3) on the ZnO(10(1-bar)0) surface has been investigated using photoelectron spectroscopy (PES) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The core-level and valence-band PES measurements reveal that ammonia adsorbs molecularly via its N atom on ZnO(10(1-bar)0) and that no dissociated species are formed at room temperature. The orientation of adsorbed NH_3 is investigated by the polarization-dependent N K-edge NEXAFS measurements, and it is found that the C_(3v) molecular axis of NH_3 is inclined in the [000(1-bar)] direction with the tile angle of 33°-41° from the surface normal.