X-Ray Spectra and Electronic Structures of CuS and Cu₂S

Abstract

The Cu Lα emission spectra in fluorescence from CuS and Cu 2 S are measured with a two-crystal vacuum spectrometer equipped with beryl crystals. The measured spectra are composed of a prominent peak and its high-energy structure. They are compared with the S L 2,3 emission, S Kβ emission, Cu L 3 absorption and S K absorption spectra reported previously to obtain information about the electronic structures of the copper sulfides. It is shown that the valence bands are composed of three parts: The upper part consists of the Cu 3 d states with considerable contribution of the S 3 p and 3 s characters, while the middle part consists of the S 3 p states with small contribution of the Cu 3 d and S 3 s characters and the lower part arises from the S 3 s states. In addition, it is shown that the hybridization between the Cu 3 d and S 3 p or 4 p orbitals is fairly large in the lower part of the conduction band of CuS.