Photoelectron spectroscopy study of surface alloying in the Au/Ni (s) 5(001) x (111) system

The growth of vapor-deposited Au on the stepped [5(001) x (111)] nickel sur face at room temperature was studied by Xray photoelectron and Anger electr on 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) bindin g 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 doubler splittin g 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 s tart: up to a Au coverage of about 0.5 Ml. The results suggest charge trans fer from Ni to Au and Au-Ni surface alloying in the submonolayer regime. (C ) 2001 Elsevier Science B.V. All rights reserved.