High Energy Resolution X-ray Spectroscopy for Actinide Science

In recent years, scientists have progressively recognized the role of electronic structure in the characterization of chemical and physical properties for actinide containing materials. High-energy resolution X-ray spectroscopy at the actinide M4,5 edges emerged as a promising direction because this method can probe actinide properties at the atomic level through the possibility of reducing the experimental spectral width below the natural core-hole life time broadening.

In this lecture, I will describe the latest progress in the field of high-energy resolution X-ray spectroscopy at the actinide M4,5 edges1. More than 10 years passed after the first X-ray spectroscopy experiment in the high-energy resolution mode on uranium systems at the U M4 edge (~3728 eV) in 20092–4. Quite a bit is known for the moment and X-ray absorption spectroscopy (XAS) or X-ray absorption near edge structure (XANES) in the high-energy resolution fluorescence detection (HERFD) mode together with resonant inelastic X-ray scattering (RIXS) or resonant X-ray emission spectroscopy (RXES) are now common techniques for studying the physics and chemistry of the f-block elements. I will show that the methods are able to a) provide fingerprint information on the actinide oxidation state and ground state character b) probe 5f occupancy, non-stoichiometry, defects c) investigate the local symmetry and effects of the crystal field5-15.