Layer structure of ultrathin Ag films on Ni/Pt(111)

The layer structure of Ag on a NiPt (111) surface after high temperature annealing was studied by Auger electron spectroscopy, depth profile of Ar ion sputtering, and low-energy electron diffraction (LEED). A structural phase p (2×2) LEED pattern was observed in one atomic monolayer (ML) on 1 ML NiPt (111) surface after annealing at 800 K. Based on observations of the change of ion sputtering rates for the Ag overlayers, the LEED pattern, and minimum strain energy, we propose a layer structure of Ag for 1 ML Ag/1 ML NiPt (111) after the 800 K annealing. The compositions in the subsurface region are 0.25 ML Ag in p (2×2) structure on the topmost layer, Ag75 Ni25 alloy in the second layer, and Ni-Pt alloy in the remaining layers of the subsurface regions.