22 research outputs found
An EXAFS and HR-XANES study of the uranyl peroxides [UO₂(η²-O₂)(H₂O)₂].nH₂O (n = 0, 2) and uranyl (oxy)hydroxide [(UO₂)₄O(OH)₆].6H₂O
Probing Covalency in the UO3 Polymorphs by U M4 edge HR- XANES
Local atomic and electronic structure investigations of uranium trioxide (UO3) crystalline phases performed by the U M4 edge HR-XANES technique is presented. The experimental U M4 edge HR-XANES spectra of α-UO3, β-UO3 and γ-UO3 polymorphic phases are compared with spectra of uranate (CaU2O7) and uranyl (UO3•1-2(H2O)) compounds. We describe a finger print approach valuable for characterization of variations of U-O axial bond lengths. Theoretical calculations of spectra using full-multiple-scattering theory (FEFF9.6 code) are performed. We have tested and selected input parameters, which provide best agreement between experimental and calculated spectra