Surface alloying of submonolayer Pb on Cu(111) studied by photoemission

The reactions of superthin Pb films on a Cu (111) surface with respect to t he coverage of Pb and annealing have been studied by synchrotron radiation photoemission. The submonolayer Pb atoms deposited at room temperature are distributed on the Cu (111) surface as two-dimensional (2D) islands. Anneal ing to 200 degrees C gives rise of Pb-Cu surface alloy formation. Analyses show that the surface alloy occurs only in the first layer of the Cu (111) surface. As a surfactant, Pb can promote 2D layer-by-layer growth of thin f ilms on Cu (111), but the Pb-Cu surface alloying may have an unfavorable ef fect on the activation process.