Growth of PtCu(100): formation of a surface alloy

Abstract Synchrotron-radiation induced core-level photoemission spectroscopy (PES) has been used to characterise the growth of Pt Cu (100) . Decomposition of the Pt 4 f 7 2 photoemission lines shows, for Pt deposition up to 2 ML, the formation during the growth process of an extended Pt-Cu surface alloy. We estimate the Pt concentration in the surface layer to be 50%. This result is consistent with the observed c(2 × 2) LEED pattern. For higher coverage, the surface alloy is destroyed and a pure and disordered Pt thin film starts to grow. Annealing of the surface alloy formed during the growth of the pure Pt thin film at 300°C leads to the same situation: formation of a surface alloy due to a kinetic blocking of the dissolution. The surface composition of this surface alloy is Cu 50 Pt 50 . This particular behaviour of the kinetics of dissolution has been already observed in Pt Cu (111) .