Electronic Structure, Localization and 5 f 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 5 f 6 configuration. PES results for PuTe are used as an indication for the 5 f 6 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 PuCoIn 5 indicate a 5 f electronic structure more localized than the 5 f s in the closely related PuCoGa 5 . There is support from the PES data for a description of Pu materials with an electronic configuration of 5 f 5 with some admixture of 5 f 6 as well as a localized/delocalized 5 f 5 description.