Interactions of NO with a Ni(100) surface

The interactions of NO with a Ni(100) surface have been investigated at 300 K by the in-situ combination of LEED, AES, ELS, thermal-desorption mass spectroscopy, EID and Δφ measurements. In the exposure region I (≲0.8 L), NO is dissociatively chemisorbed on a Ni(100) surface with an initial sticking probability of ~ 1. In the exposure region II (0.8–100 L), the coexistence of molecularly-adsorbed NO has been confirmed; the adsorbed state is characterized by electronic transitions at 4.8, 10.2, 12.0 and 15.2 eV as measured by ELS, and by first-order thermal desorption of NO at ~400 K with the activation energy of ~24 kcalmole. The surfaceto-bulk diffusion of oxygen adatoms is observed in this exposure region. In the exposure region III (100–1500 L), the formation of NiO-like layers has been observed. The surface concentration of oxygen increases monotonically with NO exposure in this region, whereas that of nitrogen is saturated; this result may possibly be explained by the penetration of oxygen adatoms during NO adsorption and by the desorption of N2 from the oxidized Ni(100) surface.