Pages: 34-42

Authors: Anton Yu. Teterin, Mikhail V. Ryzhkov, Yury A. Teterin, Labud Vukčević, Vladimir A. Terekhov, Konstantin I. Maslakov, Kirill E. Ivanov

Abstract

This work analyses the fine low energy (0-40 eV) X-ray photoelectron spectra of ThO₂, taking into account relativistic X_a-discrete variation electronic structure calculations for the ThO₈^12-(D_4h) cluster reflecting thorium's close environment in ThO₂. As a result, it was theoretically shown and experimentally confirmed that Th5f electrons in ThO₂ can participate directly (~ 0.6 Th5f electrons) in chemical bond formation. Th6p electrons were shown to be a significant part (~ 0.44 Th6p electrons) not only of inner valence molecular orbitals, but to play a significant role in outer valence molecular orbitals formation, as well. Inner valence molecular orbitals composition and sequent order were established to belong to the binding energy range of 13 eV to 40 eV. The valence electronic state density in the range of 0-40 eV in ThO₂ was also calculated. For the first time, these data allowed an interpretation of the fine X-ray photoelectron spectra (0-40 eV) and high resolution O_4,5(Th) X-ray emition spectral structure (~ 60 - ~ 85 eV) of ThO₂.

Key words: X-ray photoelectron spectra, thorium oxide, outer and inner valence molecular
orbitals

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