Surface structure analysis of oxidized Fe(100) by low energy ion scattering

Abstract

The surface structures of differently prepared oxide layers on Fe(100) have been analysed using low energy ion scattering with time-of-flight analysis. The intensity of scattered 5 keV Ne + ions and neutrals was measured as a function of elevation and azimuth of the incoming beam at a constant scattering angle, producing photograms of clean as well as oxygen covered Fe(100) surfaces. The formation of the Fe(100) p(1 × 1)-O surface structure at full monolayer coverage was confirmed by measuring azimuthal distributions of reflected Ne + ions and neutrals at specular reflection and a scattering angle of 45 °. The oxygen atoms are found to be located in the fourfold symmetrical hollows of the substrate surface. From the O − recoil intensity as a function of the elevation angle of incidence at specular reflection it was calculated that the oxygen atoms are located at a distance of 0.56 ± 0.05 Å above the first substrate layer of iron atoms. A disordered oxide layer grown on Fe(100) at room temperature reconstructs at elevated temperatures leaving a well-ordered monolayer of oxygen on top of the surface. The surface structure of this oxygen monolayer appears to be identical with respect to the surface properties found for a single monolayer of oxygen on Fe(100).