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Bibliographic Details
Main Authors: Vegelius, Johan, Shuh, David K., Butorin, Sergei M.
Format: Preprint
Published: 2025
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Online Access:https://arxiv.org/abs/2507.10723
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Table of Contents:
  • The $5f$ states were probed in ThO$_2$ and U(VI) and U(V) oxides using x-ray absorption spectroscopy at the actinide $O_{4,5}$ edges. Measured data were analyzed by several approaches including atomic, crystal-field theory and the Anderson impurity model to take into account the hybridization of actinide valence states with oxygen $2p$ states. For Th(IV), the $5f$ states are mainly affected by the crystal-field interaction with the closest neighbors as can be seen from the corresponding spectrum of ThO$_2$. In turn, for U(VI) and U(V) oxides, the U $5f$-O $2p$ hybridization and high degree of covalency in the chemical bonding play a decisive role increasing the $5f$ occupancy and consequently governing the ground and excited state properties. That is additionally illustrated by results from the calculations of the U $5d$ x-ray photoemission spectra for U(V) in the lattice of La-doped UO$_2$.