Using advanced x-ray spectroscopic methods to probe actinide 5f electronic structure

Abstract

X-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) are element specific, bulk sensitive measures of local electronic structure. As such, they make an ideal probe of actinide 5f electrons, and are situated to answer important questions about actinide covalency. To this end, I have performed resonant inelastic x-ray scattering measurements on uranium 4+ and 5+ hexachlorides to show that UVCl61- is the more covalent of the two compounds due to the energy degeneracy between the uranium and chlorine atomic orbitals. Also discussed here is the work I did to make these measurements possible using a compact, dispersive Rowland circle monochromator at the Stanford Synchrotron Radiation Lightsource. I also discuss my contributions to the goal of expanding access to XAS and XES, and in particular the development of the Clean Energy Institute X-ray Absorption Near-Edge Spectrometer, CEI-XANES, where I lead a project to create the world’s first modern laboratory mail-in XAS user facility.