Model for surface layer composition changes in sputtered alloys and compounds

Under the assumption that extracted beam energy is quickly shared among secondary cascade members of all masses, we present a model which accounts quantitatively for recently observed equilibrium surface enrichments in heavy atoms following ion bombardment of alloys and compounds. Assuming strong radiation-driven diffusion, effects of which are directly observed, and given the time required to reach equilibrium, we can calculate the thickness Δx of the enriched layer. Alternatively, knowing Δx, a calculation of the equilibration time constant is possible