Direct Determination of Oxidation States of Uranium in Mixed-Valent Uranium Oxides Using Total Reflection X-ray Fluorescence X-ray Absorption Near-Edge Spectroscopy

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• 作者：Kaushik SanyalAjay Khooha ; Gangadhar Das ; M. K. Tiwari ; N. L. Misra
• 刊名：Analytical Chemistry
• 出版年：2017
• 出版时间：January 3, 2017
• 年：2017
• 卷：89
• 期：1
• 页码：871-876
• 全文大小：453K
• ISSN：1520-6882

文摘

Total reflection X-ray fluorescence (TXRF)-based X-ray absorption near-edge spectroscopy has been used to determine the oxidation state of uranium in mixed-valent U₃O₈ and U₃O₇ uranium oxides. The TXRF spectra of the compounds were measured using variable X-ray energies in the vicinity of the U L₃ edge in the TXRF excitation mode at the microfocus beamline of the Indus-2 synchrotron facility. The TXRF-based X-ray absorption near-edge spectroscopy (TXRF-XANES) spectra were deduced from the emission spectra measured using the energies below and above the U L₃ edge in the XANES region. The data processing using TXRF-XANES spectra of U(IV), U(V), and U(VI) standard compounds revealed that U present in U₃O₈ is a mixture of U(V) and U(VI), whereas U in U₃O₇ is mixture of U(IV) and U(VI). The results obtained in this study are similar to that reported in literature using the U M edge. The present study has demonstrated the possibility of application of TXRF for the oxidation state determination and elemental speciation of radioactive substances in a nondestructive manner with very small amount of sample requirement.