Electronic Structure, Localization and 5f Occupancy in Pu Materials

The electronic structure of delta plutonium (δ-Pu) and plutonium compounds is investigated using photoelectron spectroscopy (PES). Results for δ-Pu show a small component of the valence electronic structure which might reasonably be associated with a 5f⁶ configuration. PES results for PuTe are used as an indication for the 5f⁶ configuration due to the presence of atomic multiplet structure. Temperature dependent PES data on δ-Pu indicate a narrow peak centered 20 meV below the Fermi energy and 100 meV wide. The first PES data for PuCoIn5 indicate a 5f electronic structure more localized than the 5fs in the closely related PuCoGa₅. There is support from the PES data for a description of Pu materials with an electronic configuration of 5f⁵ with some admixture of 5f⁶ as well as a localized/delocalized 5f⁵ description. (author)