Advanced x-ray spectroscopy study of Pu(III-VI) aqua ions

Understanding the relationship between bonding properties and bond stability of Pu in various oxidation states is crucial for comprehending their environmental behavior. Pu naturally exists in four oxidation states (III, IV, V, VI), which dictate its chemical properties and environmental fate. [1] Despite experimental challenges, investigating Pu chemistry, especially in aqueous solutions, is crucial for understanding interactions with ligands and chemical stability; it has also significance for nuclear waste management, fuel reprocessing, and environmental cleanup. In this presentation, we study plutonium in aqueous solution, with special focus on the bonding interaction between Pu and water ligand. We prepared Pu aqueous solutions with different oxidation states [2] and analyzed them using advanced techniques such as Pu M4,5-edge core-to-core and valence-band resonant inelastic x-ray scattering (RIXS) both at the experimental [3,4] and theoretical levels. [5] Besides, we developed computational method, calculating RIXS maps with the ligand-field density-functional theory (LFDFT) model. [5] This allows us to obtain ligand-field parameters (Slater-Condon integrals, spin-orbit coupling constant and ligand-field potential) without scaling factors or empirical corrections. ... mehrThe results show very good agreement between experiments and theory, facilitating our spectral interpretation. This joint experiment-theory effort provides insights into Pu ion coordination chemistry, and its local electronic structure, complementing standard UV-visible spectroscopy and nuclear magnetic resonance studies. We also aim at extracting long-sought details on the Pu-ligand bonding interaction, bond-covalency and stability relationship, shedding light on the Pu solvation dynamics, and informing future studies on Pu ion stability under various environmental conditions and oxidation state monitoring. This work received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (N. 101003292).
References
[1] D.L. Clark, S.S. Hecker, G.D. Jarvinen and M.P. Neu, Plutonium. In: L.R. Morss, N. Edelstein, and J. Fuger, (eds). 2008, Springer, Dordrecht.
[2] A. Tasi, X. Gaona, D. Fellhauer, M. Böttle, J. Rothe, K. Dardenne, D. Schild, M. Grivé, Mireia, E. Colàs, J. Bruno, K. Källström, M. Altmaier, and H. Geckeis, Radiochim. Acta, 106, 259-279 (2018).
[3] T. Vitova, I. Pidchenko, D. Fellhauer, P.S. Bagus, Y. Joly, T. Prüssmann, S. Bahl, E. Gonzalez-Robles, J. Rothe, M. Altmaier, M.A. Denecke and H. Geckeis, Nat. Commun., 8, 16053 (2017).
[4] T. Vitova, I. Pidchenko, D. Fellhaur, T. Prüssmann, S. Bahl, K. Dardenne, T. Yokosawa, B. Schimmelpfennig, M. Altmaier, M. Denecke, J. Rothe and H. Geckeis, Chem. Commun., 54, 12824 (2018).
[5] H. Ramanantoanina, Computation, 10, 70 (2022).