Structure of x-ray photoelectron 2p and 1s spectra and x-ray K? emission line of copper in YBa2Cu3O7?? and CuO, on the basis of SCF-X?-SW calculations

Abstract

Through an analysis of the electronic structure of the ground state and 2p and 1s hole states of the CuO4 6− cluster, modeling the immediate environment of a copper atom (one of the two types) in YBa2Cu3O7−δ and the immediate environment of the copper atom in CuO, it has been shown that upon ionization of core levels of copper, there is a radical reconstruction of the valence band of the cluster with a change in character of the chemical bond from covalent to ionic. Along with this, charge is transferred from the copper-oxygen bond to the central atom. Ionization of core levels leads to intense excitation of electrons into the upper semifilled valence level of the cluster 3b1g, and also leads to the appearance in the x-ray photoelectron and x-ray spectra (Kα spectra, for example) of intense satellite lines with strong multiplet splitting (with the exception of the satellite of the x-ray photoelectron 1s spectrum). We have confirmed the interpretation of the x-ray photoelectron 2p3/2 (2p1/2) spectrum and have predicted the form of the x-ray photoelectron 1s spectrum of copper(II). On the basis of the same approach, a complex structure has been predicted for the x-ray Kα emission line and it has been confirmed that the shift of this line in compounds of copper(II) must be made with some caution, as the shift may be due (for example) to a change in relative intensities of the main and satellite lines, which are located relative to each other at a distance of ≃0.4 eV.