Direct assessment of the variations in the intensity ratios of M and L X-ray lines of U in various compounds by total reflection X-ray fluorescence spectrometry

A systematic study, to assess the variations in the intensity ratios of uranium M and L X-ray lines, was carried out using Total reflection X-Ray Fluorescence (TXRF) spectrometry. In order to establish a co-relation between the variations in the intensity ratios of uranium and its oxidation state, various compounds of uranium having oxidation states of 0, +4, mixed oxide and + 6 were prepared by solid state route. Uranyl nitrate solution was prepared by dissolving powders of U3O8 in nitric acid. The U M lines were excited using monochromatised Cr Kα and the U L lines were excited using monochromatised Rh Kα excitation source. The M- and L- X-ray lines of U were measured using a Silicon Drift Detector (SDD) with a special ultrathin polymer entrance window, AP 3.3, of 300 nm thickness. The intensity ratios of U M lines (Mζ, Mβ and Mγ) with respect to U Mα and U L lines (Ll, Lβ and Lη) with respect to Lα were determined experimentally in different compounds of U. Statistical evaluations showed a significant difference in the mean values of the intensity ratios of different oxidation states in uranium. [Display omitted] •Establish co-relation between changes in intensity ratios and oxidation states.•Direct TXRF method for assessment of variations in intensity ratios of U X- rays.•An important application for expansion of XRF for speciation studies.