Adsorption of Antimony on Au(001).

Antimony overlayers on a clean Au(001) surface were prepared by surface segregation on a sputtered and annealed, Sb-doped gold single crystal. Valence band Photoemission data, taken with photon energies between 35 and 150 eV, exhibit an Sb 5p contribution at the Fermi energy at the higher energies. Core- level photoemission data yield surface-atom shifts for the Au 4f core electrons of +0.44 eV and +0.90 eV, opposite in sign to that of the clean Au surface, and suggestive of loss of charge from the Au surface layer. Sb 4d core level spectra have the asymmetric line shape associated with metallic screening with a many-body singularity index of 0.08. This value is significantly larger than that of bulk gold, and suggests screening by electrons in Sb-derived states at the Fermi level.