Unoccupied states and the charge transfer in Cu-Pt alloys studied by bremsstrahlung isochromat spectroscopy and X-ray photoelectron spectroscopy

We have measured the unoccupied partial Pt 5d densities of states in Cu-Pt alloys by using bremsstrahlung isochromat spectroscopy (BIS). We found that the Pt 5d states are gradually filled up as the Pt concentration is reduced. We have also determined the charge redistribution between the Pt and the Cu atoms from the core-level binding-energy shifts in the X-ray photoelectron spectroscopy (XPS) and the intensity of the unoccupied Pt d states in the BIS spectra. We found that interatomic charge transfer is generally small and that intra-atomic charge redistibution between s and d electrons is more important for the change of electronic structures in alloys.