Atomic origin of the Si core-level photoemission components in the C(2X2)Si-Cu(110) surface alloy

High-resolution synchrotron-radiation photoemission spectroscopy has been u sed to investigate the Si 2p core-level peak of the c(2 x 2) Si-Cu(110) sur face alloy. In the photoemission spectrum several components can be clearly distinguished where only;one would be expected. In order to know the atomi c origin of these shifted components, we have correlated scanning tunnellin g microscope images to photoelectron-diffraction azimuthal scans on the shi fted peaks recorded at the same coverage. From this analysis insights about the mechanisms of the surface-alloy formation can be made. [S0163-1829(98) 05248-5].