Chemisorption of NO on Pd(100), (111) and (110) surfaces studied by AES, UPS and XPS

Abstract

Abstract The chemisorption of nitric oxide on the Mo(100) and Mo(111) surfaces at room temperature has been studied by Auger electron spectroscopy (AES), ultra-violet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS). NO adsorbs dissociatively on the Mo(100) surface at lower coverage at room temperature, and a small amount of molecular NO exists on the fully NO-covered Mo(100) surface. On the other hand, the molecular NO is not observed even on the fully NO-covered Mo(111) surface. The oxygen atoms on the Mo(100) surface penetrate into the lattice at room temperature, but on Mo(111) the oxygen atoms penetrate into the lattice with increasing temperature and appear on the surface again at high temperature. The adsorption state of a part of the nitrogen atoms adsorbed on the Mo(100) surface changes at higher temperature. The peak due to molybdenumnitrides appears at 7.5 eV on Mo(100) and at 8.0 eV on Mo(111) in the UP spectra. The nitrides on Mo(100) desorb in the 673–873 K range and on Mo(111) in the 773–1073 K range. A peak caused by surface oxide appears at 7.2 eV for both of Mo(100) and Mo(111) surfaces above 1300 K. The differences between the adsorption of NO on Mo(100) and Mo(111) are caused by a different temperature-induced rearrangement of adsorbates.