Kinetic study of the formation of a surface-confined Cu₅₀Pt₅₀ alloy

Using Auger electron spectroscopy we demonstrate the determination of the energy barrier for the formation of a surface-confined Cu₅₀Pt₅₀(111) bilayer alloy. Starting with one monolayer of Cu on Pt(111) concentration changes are determined as a function of annealing temperature up to 600 K and annealing time. Comparison of the experimental data with Monte Carlo simulations give the best result for the assumption of a Cu₅₀Pt₅₀ surface alloy yielding an energy barrier for interlayer mixing of 1.11±0.12 eV/atom. Concomitant valence band photoemission spectra also indicate the alloy formation.