Core and Valence Structures in K beta X-ray Emission Spectra of Chromium Materials

Abstract

We analyze the core and valence transitions in chromium in a series of materials with a number of different ligands and including the oxidation states: Cr-II, Cr-III, Cr-IV, and Cr-VI. To study the core-to-core transitions we employ the CTM4XAS program and investigate the shapes, widths, intensities, and energy positions of the K beta(1,3) and K beta' lines in each oxidation state. The theoretical spectra are compared with experimental data obtained with synchrotron radiation. We found that the K beta(1,3) peak shifts to higher energy with increasing spin state. In addition, the widths of the K beta(1,3) peak increases as the oxidation state decreases, which we explain from the increased spread of the multiplet structures. In the K beta' structure the presence of two peaks in Cr-II, Cr-III, and Cr-IV is due to the large 3p3d exchange interaction. For the analysis of the valence transitions we utilize the DV-Xa method. We study the dependence of the relative intensities of the K beta" and K beta(2,5) structures on symmetry, bond length, and the effective number of 3d and 4p electrons in different chemical environments.