High-resolution synchrotron-radiation photoemission spectroscopy has been used to investigate the Si $2p$ core-level peak of the $c(2\mathrm{}\times 2)$ Si-Cu(110) surface alloy. In the photoemission spectrum several components can be clearly distinguished where only one would be expected. In order to know the atomic origin of these shifted components, we have correlated scanning tunnelling microscope images to photoelectron-diffraction azimuthal scans on the shifted peaks recorded at the same coverage. From this analysis insights about the mechanisms of the surface-alloy formation can be made.

• Received 14 September 1998

DOI:https://doi.org/10.1103/PhysRevB.59.3070