Electronic structure of different Pt-Cu surfaces

Soft-x-ray photoemission experiments, utilizing the existence of the Cooper minimum in the Pt5d photoionization cross section, have demonstrated that the widths and peak shapes of the Cu3d---derived states of different Pt-Cu surfaces vary according to the atomic coordination between Cu and Pt atoms. For the surface with the largest atomic coordination, namely, the PtCu(111) surface, strong Pt5d-Cu3d hybridization is suggested to exist between {~} - 1.4 eV and the Fermi level. The feature attributed to such hybridization has a strength which depends on Pt-Cu nearest neighbors in the first approximation. The energy shifts of these Pt---Cu3d centroids, relative to pure Cu, seem to correlate with the Pt---Cu2p3/2 core-level shifts observed with conventional x-ray excitation.