Electronic structure of different Pt-Cu surfaces

Abstract

Soft-x-ray photoemission experiments, utilizing the existence of the Cooper minimum in the $\mathrm{Pt}5d$ photoionization cross section, have demonstrated that the widths and peak shapes of the $\mathrm{Cu}3d$—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 $\mathrm{Pt}5d-\mathrm{Cu}3d$ 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—$\mathrm{Cu}3d$ centroids, relative to pure Cu, seem to correlate with the Pt—$\mathrm{Cu}2p_{\frac{3}{2}}$ core-level shifts observed with conventional x-ray excitation.