X-ray Spectroscopic Study of U6p,5f Electronic Levels in γ-UO3

Abstract

The fine structures of X-ray photoelectron (XPE) spectra of low-energy electrons and conversion electron spectra of γ-UO3 (0-40 eV energy) were analyzed taking into account relativistic calculations based on the Xα discrete variation method of the electronic structure of uranium cluster [(UO2)O4]6- (D4h symmetry group) representing the closest coordination of uranium in γ-UO3. The theoretical and experimental data show that U5f electrons directly participate in the chemical bonding. The density of states of 5f valence electrons in uranium trioxide was calculated. At the same time, U6p electrons participate in formation of both inner and outer valence molecular orbitals, and the density of such 6p states in uranium trioxide was also calculated. The order of the inner valence molecular orbitals in the 13-40 eV range was determined, which is of particular importance for development of a procedure to evaluate the uranium-ligand bond distances in axial and equatorial directions in uranyl compounds using their X-ray photoelectron spectra in the range of inner group) representing the closest coordination of uranium in γ-UO3. The theoretical and experimental data showthat U5f electrons directly participate in the chemical bonding. The density of states of 5f valence electronsin uranium trioxide was calculated. At the same time, U6p electrons participate in formation of both inner andouter valence molecular orbitals, and the density of such 6p states in uranium trioxide was also calculated. The order of the inner valence molecular orbitals in the 13-40 eV range was determined, which is of particular importance for development of a procedure to evaluate the uranium-ligand bond distances in axial andequatorial directions in uranyl compounds using their X-ray photoelectron spectra in the range of innermolecular orbitals.