Developments of high resolution X-ray spectroscopic tools for probing structural properties of actinides system from the metal and ligand perspective

High energy resolution X-ray absorption and emission spectroscopic techniques became indispensable methods in actinide and radionuclide research.1-5 One important motivation is studies concerning the mobilization and retention of long-lived actinides and fission products in geochemical processes relevant for safety studies of a potential deep geological nuclear waste repository.3-4 In-depth insight into the actinide-ligand binding properties is a main application of these novel experimental techniques too. 6 Development at the ACT experimental station of the CAT-ACT wiggler beamline at the Karlsruhe Institute of Technology (KIT) Light Source will be discussed. One experimental technique especially powerful to differentiate oxidation states of actinides (An) is the An M4,5-edge high-energy resolution X-ray absorption near-edge structure (HR-XANES). 4 This presentation highlights the latest technological developments at the ACT station, enabling HR-XANES spectroscopic technique for samples with low radionuclide loading down to 1 ppm in combination with a cryogenic sample environment reducing beam-induced sample alterations. 7-8 It paves the way for the examination of coupled redox/solid-liquid interface reactions. ... mehr8 Examples of applications of core-to-core and valence band resonant inelastic X-ray scattering (CC-RIXS and VB-RIXS) for probing the electronic structure and binding properties of the actinide elements will be illustrated. First results obtained using a newly developed versatile chamber for soft X-ray spectroscopy at the X-SPEC beamline at the KIT Light Source will be discussed.
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