Photoelectron spectroscopy study of surface alloying in the Au/Ni (s) 5(0 0 1) × (1 1 1) system

Abstract

The growth of vapor-deposited Au on the stepped [ 5(0 0 1)×(1 1 1) ] nickel surface at room temperature was studied by X-ray photoelectron and Auger electron spectroscopy (XPS/XAES) and ultraviolet photoelectron spectroscopy (UPS) for Au coverages ranging from about 0.2 up to 13 Ml. The Au 4f 7/2 binding energy is initially lower than that of metallic gold and reaches its bulk value above 4 Ml. Helium II UPS exhibits an initial Au 5d doublet splitting of 1.5 eV, which increases up to the bulk value of 2.7 eV after 13 Ml of gold deposition, as well as an abnormally strong attenuation of the Ni 3d state up to a Au coverage of about 0.5 Ml. The results suggest charge transfer from Ni to Au and AuNi surface alloying in the submonolayer regime.