LOW-ENERGY ION-SCATTERING STUDY OF OXYGEN-ADSORPTION ON NI[100]

Using 1 keV He4 ion scattering at fixed scattering angles of 48° and 90° with a simple spectrometer based on a cylindrical mirror analyser we have studied the clean Ni{100} and Ni{100} (√2 × √2)R45°-OE structure. Assuming that this oxygen structure is well-known from earlier LEED studies we have attempted to understand the azimuthal anisotropies of the ion scattering signals by considering the shadowing processes involved. Simple elastic scaterring shadowing alone is not able to account for the results and we propose that the adsorbate can also shadow by a localised neutralisation process. This appears to account qualitatively for our results and is also consistent with earlier structure analyses using ISS but not specifically taking account of this process. © 1979.