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

A systematic X-ray absorption study at actinide N 6,7 (4f → 6d transitions) edges was performed for light-actinide oxides including data obtained for the first time for NpO 2, PuO 2, and UO 3. 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 L 2,3 (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 N 6,7 spectral shape to changes in the compound crystal structure. Finally, for nonstoichiometric NpO 2-x, the filling of the entire band gap with Np 6d states was observed thus supporting a phase coexistence of Np metal and stoichiometric NpO 2 which is in agreement with the tentative Np-O phase diagram.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [4]
  1. Uppsala Univ. (Sweden). Dept. of Physics and Astronomy
  2. Uppsala Univ. (Sweden). Dept. of Physics and Astronomy; RIKEN, Saitama (Japan). Center for Emergent Matter Science
  3. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  4. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Chemical Sciences Division
Publication Date:
Grant/Contract Number:
AC02-05CH11231; 269903
Type:
Accepted Manuscript
Journal Name:
Analytical Chemistry
Additional Journal Information:
Journal Volume: 88; Journal Issue: 8; Journal ID: ISSN 0003-2700
Publisher:
American Chemical Society (ACS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); Swedish Research Council (SRC); Swedish National Infrastructure for Computing (SNIC); European Atomic Energy Community
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
OSTI Identifier:
1436135

Butorin, Sergei M., Modin, Anders, Vegelius, Johan R., Suzuki, Michi-To, Oppeneer, Peter M., Andersson, David A., and Shuh, David K.. Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides. United States: N. p., Web. doi:10.1021/acs.analchem.5b04380.
Butorin, Sergei M., Modin, Anders, Vegelius, Johan R., Suzuki, Michi-To, Oppeneer, Peter M., Andersson, David A., & Shuh, David K.. Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides. United States. doi:10.1021/acs.analchem.5b04380.
Butorin, Sergei M., Modin, Anders, Vegelius, Johan R., Suzuki, Michi-To, Oppeneer, Peter M., Andersson, David A., and Shuh, David K.. 2016. "Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides". United States. doi:10.1021/acs.analchem.5b04380. https://www.osti.gov/servlets/purl/1436135.
@article{osti_1436135,
title = {Local Symmetry Effects in Actinide 4f X-ray Absorption in Oxides},
author = {Butorin, Sergei M. and Modin, Anders and Vegelius, Johan R. and Suzuki, Michi-To and Oppeneer, Peter M. and Andersson, David A. and Shuh, David K.},
abstractNote = {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. Finally, 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.},
doi = {10.1021/acs.analchem.5b04380},
journal = {Analytical Chemistry},
number = 8,
volume = 88,
place = {United States},
year = {2016},
month = {3}
}