Relaxation and decay of an atom with a core hole. III

Abstract

The resonant core-electron excitation to a narrow empty band can result in a resonant state or a core-exciton-like bound state. The transition from the resonant state to the bound state depends on the relative size of the core-hole–excited-electron interaction strength to the band-width of the density of unoccupied states of a particular angular momentum character in the ground state. In a charge transfer system the hybridization of a localized empty acceptor-level with a donor band, results in a split-off bound level and/or a state in the band. The quasi-particle approximation could break down for a state in the band so that the concept of a resonant state becomes illusory. The core-hole state in which such a split-off bound level below the Fermi level is occupied by the resonant core-electron excitation or the core-hole screening electron, could become a fully relaxed core-hole state.