INITIAL-STAGES OF OXIDATION OF MG AND INELASTIC ION-SCATTERING

Results of a study of inelastic ion scattering on a polycrystalline Mg surface during the initial stages of oxidation is presented. This is supplemented by AES measurements and work function determination using autoionising state electron spectroscopy. The AES oxygen peak intensity rises rapidly for exposures below 2 L and saturation is almost reached at 5 L. A strong decrease in the work function is found below 2 L. In this region a dramatic fall in the probability of excited state production in the scattered flux is observed and found to be state selective. These relative changes are indicative of changes in electron transfer rates, which are thus determined as a function of exposure. The general decrease of the intensity of excited states is interpreted as due to screening of Mg atoms by the adsorbate starting from small coverages, below 2 L. The assignment of excited sputtered Mg states is discussed.