Dilution effect on the U-5f states: U in an Ag matrix

The electronic structure of U-diluted in an Ag matrix has been studied in situ by ultraviolet and X-ray photoelectron spectroscopy (UPS and XPS, respectively). UxAg100−x thin films (x = 0-100 at.%) were produced by sputter co-deposition in an Ar atmosphere. UPS spectra of the Ag-4d line indicate formation of a homogeneous mixture despite the fact that U and Ag do not form stable alloys. A major goal of this work was to find out whether the dilution of U atoms in an inert matrix with no bonding states induces the localisation of the U-5f states. Both U-4f core level spectra and the U-5f spectra indicate U-5f delocalisation, down to 5 at.% of uranium in UxAg100−x films.