Core photoemission theory of semiconducting rare earth compounds

Abstract

Within the Anderson model and in the case of a filled valence band for which the electron-electron interaction can be treated exactly, we first give a formal description of the corresponding core-photoemission spectrum. Our calculations have been motivated by a number of X photoemission experiments which show up final states problems. We discuss our results in terms of the relative positions of the final ' f ' states with respect to the valence band states and in terms of the hybridization between those two types of states. Especially, if the hybridization amplitude is too small (≾ 1.0 eV) it is not possible to reproduce correctly the experimental (3d) spectrum of CeO2 ; for somewhat larger hybridization (∼ 1.5 eV) we are able to fit that three peaked spectrum at least in a semiquantitative way. As a consequence, CeO2 can well be considered as an intermediate valent system.