Diffusion by atomic place exchange in ultrathin iron films on Ag(100): An ion scattering spectroscopy study

The surface composition of ultrathin (0-10 ML) iron films deposited on a well defined Ag(100) substrate at 140 K has been investigated by ion scattering spectroscopy. The data unambiguously show the occurrence of intermixing. The concentration of Ag at the surface decreases rather rapidly with the film thickness but it is still relevant (~10%) even in the case of the thickest layer. The data are interpreted in terms of an atomic place exchange between silver and incident iron atoms at the surface of the growing film.