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Accueil > Séminaires > 2018

First principle simulation of the EPR g-values in actinide complexes

Julie Jung, Los Alamos National Laboratory (USA)

Salle de séminaire IRSAMC (3ème étage du bât. 3R1), Mardi 13 Novembre, 11h - 12h

Being able to selectively extract the minor actinides from spent nuclear fuel is a critical step toward better handling of nuclear waste. The use of extracting ligands is currently seen as the most promising route to reach this goal. Unfortunately, this is hard to achieve in practice, owing to the chemical similarity between the minor actinides and the other elements contained in the waste (e.g. lanthanides).

To overcome this problem, first step is to get a better understanding of actinide-ligand bonding. The best way to do this is to combine highly sensitive spectroscopic techniques with first principle simulations, in order to get an accurate description of the electronic structure and the bonding features of actinide-ligand assemblies [1].

In that context, the focus of this presentation will be on the use of complete active space self-consistent field (CASSCF) calculations in combination with electron paramagnetic resonance (EPR) spectroscopy [2] to analyze bonding in a series of uranium(V) complexes [3]. Indeed, the CASSCF method allows for proper description of both the spin-orbit interaction and the electron correlation effects stemming from the partially filled 5f and/or 6d shells of uranium. On the other hand, EPR spectroscopy can provide very detailed information about the electronic ground state of uranium complexes. Hence, from confronting theory with experiments through ligand field theory, it is possible to analyze the strength and the nature of uranium-ligand bonding.

Overall, this work shows how the synergy between experiment and theory can be used to understand the electronic structure and spectroscopic properties of actinide complexes.

References.
[1] Jung, J., Atanasov, M. and Neese, F. (2017) Inorg. Chem., 56, 8802-8816.
[2] Neese, F. and Solomon, E.I. (2002) Magnetism : Molecules to Materials IV (CH 9), Ed. Miller, J.S. and Drillon, M., Wiley-VCH Verlag GmbH & Co. KGaA.
[3] Lukens, W.W., Edelstein, N.M., Magnani, N., Hayton, T.W., Fortier, S. and Seaman, L.A. (2013) J. Am. Chem. Soc., 135, 10742-10754.