The role of the 5f valence orbitals of early actinides in chemical bonding

T Vitova (1) , I Pidchenko (1) , D Fellhauer (1) , P S Bagus (2) , Yves Joly (3) , T Pruessmann (1) , S Bahl (1) , E Gonzalez-Robles (1) , J Rothe (1) , M A Altmaier (1) , M A Denecke (1) , H Geckeis (1)

1 Karlsruhe Institute of Technology (KIT), Institute for Nuclear Waste Disposal (INE)
2 Department of Chemistry
3 NEEL - SIN - Surfaces, Interfaces et Nanostructures

One of the long standing debates in actinide chemistry is the level of localization and participation of the actinide 5f valence orbitals in covalent bonds across the actinide series. Here we illuminate the role of the 5f valence orbitals of uranium, neptunium and plutonium in chemical bonding using advanced spectroscopies: actinide M 4,5 HR-XANES and 3d4f RIXS. Results reveal that the 5f orbitals are active in the chemical bonding for uranium and neptunium, shown by significant variations in the level of their localization evidenced in the spectra. In contrast, the 5f orbitals of plutonium appear localized and surprisingly insensitive to different bonding environments. We envisage that this report of using relative energy differences between the 5fd/f and 5fp*/5fs* orbitals as a qualitative measure of overlap-driven actinyl bond covalency will spark activity, and extend to numerous applications of RIXS and HR-XANES to gain new insights into the electronic structures of the actinide elements.

Mots clés: Actinides XANES RIXS

Domaines: Autre [cond-mat.other]; Chimie théorique et/ou physique; Science des matériaux [cond-mat.mtrl-sci]

T Vitova, I Pidchenko, D Fellhauer, P S Bagus, Yves Joly, et al.. The role of the 5f valence orbitals of early actinides in chemical bonding. Nature Communications, 2017, 8, pp.16053. ⟨10.1038/ncomms16053⟩. ⟨hal-01563863⟩