Crystal-field splitting strength of U-6d orbitals in NaUO3, KUO3 and RbUO3

Here, the uranium valence electronic structures in the perovskite-based ternary
uranate systems NaUO3, KUO3 and RbUO3 are reported on the basis of high energy resolved fluorescence-detected X-ray absorption spectroscopy experiments at the U L3 edge and relativistic quantum chemistry calculations based on
density functional theory. Advanced theoretical simulations allowed us to
identify the origin of spectral features and to assess the impact of structural
distortion within the oxygen octahedra. The octahedral crystal-field strength
extracted from both experiments and calculations is reported for all three
compounds