Towards the Understanding of the Electronic Structure of the VO₄^3-Ion

Abstract

The experimental X-ray K-emission and absorption spectra of Na,VO, , the L-emission spectrum of YVO,, and the XPS and APS spectra of YVO, are compared with the energy diagram of molecular orbitals obtained by a cluster-model calculation for the orthovanadate ion VO:-.It is found that the gross features of all the spectroscopies can be understood if core hole relaxation and localization of the screening charge is properly taken into account, admitting, e.g., excitonic effects in excitation spectra. Presence of a core hole leads to local breakdown of the one-particle orbital model for the solid, and the excitation and decay processes should more appropriately be described by transitions between atomic-like configurations. Usefulness of several other, complementary spectroscopic studies is anticipated. Refinement of the interpretation is expected to come from both an improvement of the cluster calculations and the inclusion of the admittedly non-negligible environmental effects such as the crystal-field effects, the cation contribution in specific compounds, etc. A few experimental aspects with possible implications on the interpretation of data are commented.