Core hole screening in oxides and screening variations due to oxidation of elements

Abstract

Core hole screening in oxides has been studied by means of a linear response method where the dielectric properties are described by a wave vector dependent dielectric function and the core hole perturbation by a suitable pseudopotential. Single hole relaxation energies corresponding to the oxygen 2s level and relative cross-relaxation energy differences corresponding to KL 1 L 1 oxygen Auger transition have been calculated for different oxides. The latter have been compared with values deduced from experimental spectra of Humbert, showing a general good agreement. However, using the same model, screening variations during the oxidation process can be obtained, such as the difference of the core hole relaxation energy relative to the simple element and the oxidized element. In this way, single hole relaxation energy variations have been calculated when a few simple transition metals and semiconductors are oxidized. Then the latter have been compared with the Auger parameter changes caused by the oxidation and deduced from the experimental spectra of Wagner. Some comments with regard to the model and the efficiency of screening can be made.