title: Direct Determination of Oxidation States of Uranium in Mixed-Valent Uranium Oxides Using Total Reflection X-ray Fluorescence X-ray Absorption Near-Edge Spectroscopy.
abstract: 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 U3O8and U3O7uranium oxides. The TXRF spectra of the compounds were measured using variable X-ray energies in the vicinity of the U L3edge 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 L3edge 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 U3O8is a mixture of U(V) and U(VI), whereas U in U3O7is 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.
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.|Homi Bhabha National Institute , Mumbai 400094, India.
authors.forename: Kaushik
authors.identifier: 0000-0001-5964-970X
authors.initials: K
authors.lastname: Sanyal
authors.affiliation: Synchrotrons Utilisation Section, Raja Ramanna Centre for Advanced Technology , Indore 452013, India.
authors.forename: Ajay
authors.initials: A
authors.lastname: Khooha
authors.affiliation: Synchrotrons Utilisation Section, Raja Ramanna Centre for Advanced Technology , Indore 452013, India.|Homi Bhabha National Institute , Mumbai 400094, India.
authors.forename: Gangadhar
authors.initials: G
authors.lastname: Das
authors.affiliation: Synchrotrons Utilisation Section, Raja Ramanna Centre for Advanced Technology , Indore 452013, India.|Homi Bhabha National Institute , Mumbai 400094, India.
authors.forename: M K
authors.initials: MK
authors.lastname: Tiwari
authors.affiliation: Fuel Chemistry Division, Bhabha Atomic Research Centre , Mumbai 400085, India.|Homi Bhabha National Institute , Mumbai 400094, India.
authors.forename: N L
authors.identifier: 0000-0002-8483-4912
authors.initials: NL
authors.lastname: Misra