Photoelectron spectra of thin alloy films: measurements and relativistic calculations for the system c(2x2) CuMn on Cu(100)

Deposition of half a monolayer of manganese on a copper (100) surface at ro om temperature leads to the formation of a surface alloy with a c(2 x 2) st ructure. Angle-resolved photoelectron spectra of this structure were measur ed by ultraviolet photoelectron spectroscopy (UPS) in the regime of He I ra diation. For the same geometries as in the experiments, fully relativistic calculati ons were performed in the framework of the one-step model of photoemission first proposed by Pendry and subsequently developed further by several auth ors. The layer-dependent potentials used were obtained by a tight-binding-l inear muffin-tin orbitals slab calculation. In this contribution, a comparison is shown between measured and calculated spectra, as well as between the spectra of pure copper and the surface all oy on copper. The outward relaxation of the manganese atoms by 0.3 Angstrom as determined by I-V low-energy electron diffraction analysis is taken int o account, but affects the spectra only slightly. The aim of this contribut ion is to show the influence of alloying on the UPS spectra and how well th e theoretical model is able to describe such a heteroepitaxial system. (C) 1999 Elsevier Science B.V. All rights reserved.