Bonding interactions of the actinide elements probed by high resolution X-ray spectroscopy

Understanding the electronic structure and chemical bonding properties of the actinide (An) elements poses a great challenge and frontier in fundamental chemistry and physics.1 The An4,5 absorption edge core-to-core and valence band resonant inelastic X-ray scattering (CC/VB-RIXS) and high energy resolution X-ray absorption near edge structure (HR-XANES) techniques probe the occupied and unoccupied parts of the valence band of the actinide elements with extraordinary energy resolution and thus unique information on the chemical bond can be obtained.1 A deep insight into the An electronic structures is for example essential to understand actinide environmental behaviour. All An M4,5 edge RIXS and HR-XANES studies are performed at the ACT station of the CAT-ACT beamline at the KIT Light Source.2
Spectroscopic and computational tools for probing in detail the An-ligand (U, Np, Pu or Am) bond covalency will be discussed.1, 3, 4 It will be shown that An 3d4f CC-RIXS can be used to measure spin-orbit coupling effects and is a probe of the localised and delocalised f electron density on the An atom. It will be demonstrated that the energy positions of the resonant peaks in the CC-RIXS/HR-XANES spectra strongly depend on the electron-electron/hole interactions in the intermediate and final state of the excitation process and thus these two effects are of importance for close agreement of calculated and experimental spectra. ... mehr
1.Vitova, T.; Pidchenko, I.; Fellhauer, D.; Bagus, P. S.; Joly, Y.; Pruessmann, T.; Bahl, S.; González-Robles, E.; Rothe, J.; Altmaier, M.; Denecke, M. A.; Geckeis, H., The role of the 5f valence orbitals of early actinides in chemical bonding. Nature Communications 2017, 8, 16053.
2.Schacherl, B.; Prussmann, T.; Dardenne, K.; Hardock, K.; Krepper, V.; Rothe, J.; Vitova, T.; Geckeis, H., Implementation of cryogenic tender X-ray HR-XANES spectroscopy at the ACT station of the CAT-ACT beamline at the KIT Light Source. Journal of Synchrotron Radiation 2022, 29 (1), 80-88.
3.Bagus, P. S.; Schacherl, B.; Vitova, T., Computational and Spectroscopic Tools for the Detection of Bond Covalency in Pu(IV) Materials. Inorganic Chemistry 2021, 60 (21), 16090-16102.
4.Vitova, T.; Pidchenko, I.; Schild, D.; Prüßmann, T.; Montoya, V.; Fellhauer, D.; Gaona, X.; Bohnert, E.; Rothe, J.; Baker, R. J.; Geckeis, H., Competitive Reaction of Neptunium(V) and Uranium(VI) in Potassium–Sodium Carbonate-Rich Aqueous Media: Speciation Study with a Focus on High-Resolution X-ray Spectroscopy. Inorganic Chemistry 2020, 59 (1), 8-22.