Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides

Sergei M. Butorin, Anders Modin, Johan R. Vegelius, Michi To Suzuki, Peter M. Oppeneer, David A. Andersson, David K. Shuh

Research output: Contribution to journalArticlepeer-review

8 Citations (Scopus)

Abstract

A systematic X-ray absorption study at actinide N6,7 (4f → 6d transitions) edges was performed for light-actinide oxides including data obtained for the first time for NpO2, PuO2, and UO3. The measurements were supported by ab initio calculations based on local-density-approximation with added 5f-5f Coulomb interaction (LDA+U). Improved energy resolution compared to common experiments at actinide L2,3 (2p → 6d transitions) edges allowed us to resolve the major structures of the unoccupied 6d density of states (DOS) and estimate the crystal-field splittings in the 6d shell directly from the spectra of light-actinide dioxides. The measurements demonstrated an enhanced sensitivity of the N6,7 spectral shape to changes in the compound crystal structure. For nonstoichiometric NpO2-x, the filling of the entire band gap with Np 6d states was observed thus supporting a phase coexistence of Np metal and stoichiometric NpO2 which is in agreement with the tentative Np-O phase diagram.

Original languageEnglish
Pages (from-to)4169-4173
Number of pages5
JournalAnalytical Chemistry
Volume88
Issue number8
DOIs
Publication statusPublished - 2016 May 3

ASJC Scopus subject areas

  • Analytical Chemistry

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