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

• Published in: Nature communications Vol. 8; no. 1; p. 16053
• Main Authors: Vitova, T., Pidchenko, I., Fellhauer, D., Bagus, P. S., Joly, Y., Pruessmann, T., Bahl, S., Gonzalez-Robles, E., Rothe, J., Altmaier, M., Denecke, M. A., Geckeis, H.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 06-07-2017; Nature Publishing Group; Nature Portfolio
• Subjects: 639/638/263/910; Actinides; chemical bonding; Chemical bonds; Chemical Sciences; Condensed Matter; Covalence; Covalent bonds; Energy consumption; Humanities and Social Sciences; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Localization; Materials Science; multidisciplinary; Neptunium; or physical chemistry; Orbitals; Other; Physics; Plutonium; Science; science & technology; Science (multidisciplinary); Theoretical and; Uranium; Actinides XANES RIXS
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms16053

One of the long standing debates in actinide chemistry is the level of localization and participation of the actinide 5
f
valence orbitals in covalent bonds across the actinide series. Here we illuminate the role of the 5
f
valence orbitals of uranium, neptunium and plutonium in chemical bonding using advanced spectroscopies: actinide M
4,5
HR-XANES and 3
d
4
f
RIXS. Results reveal that the 5
f
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 5
f
orbitals of plutonium appear localized and surprisingly insensitive to different bonding environments. We envisage that this report of using relative energy differences between the 5
f
δ/φ and 5
f
π*/5
f
σ* 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.
Understanding the chemistry of heavy radioactive elements is crucial to harnessing them for fuel and medicine. Here, the authors combine advanced X-ray spectroscopy and modelling to the study the chemical bonding of the 5
f
valence orbitals of uranium, neptunium and plutonium.