No abstract

A clean Ni(100) surface and a surface exposed to 1802, have been studied by high-energy ion scattering and nuclear reaction analysis. The structure of the clean and the exposed surfaces is studied by 750 keV He + ion scattering in combination with channeling and blocking. The results are consistent with results obtained by medium-energy ion scattering. Absolute oxygen contents are measured using the 180(p, a)lSN nuclear resonance at Ep = 1766 keV. It is found that the oxygen content of the surface for which the c(2 X 2) LEED pattern is observed, is 0.42 + 0.04 of a Ni(100) monolayer. The oxygen content of a saturated oxide layer is 2.4_+0.2 of a monolayer. Furthermore, it is concluded that the saturated oxide layer consists of stoichiometric NiO.