Electronic structure of α- and δ-Pu from photoelectron spectroscopy

We report photoemission results on alpha- and delta-Pu using a laser plasma light source (LPLS) as well as He light as the exciting radiation. The LPLS isa pseudocontinuum tunable Light source with intensities rivaling some second-generation synchrotrons. Both phases of Pu display a narrow, temperature-independent, 5f-related feature at the Fermi energy, which is narrower in delta-Pu than in alpha-Pu, suggestive of possible heavy-fermion-like behavior. In both alpha-Pu and delta-Pu the photon-energy dependence of this feature suggests some 6d admixture, albeit somewhat smaller in delta-Pu. In this respect it differs qualitatively from Ce and U heavy fermions.