MOLECULAR-DYNAMICS OF PLACE EXCHANGE OF METAL ADATOMS WITH FCC (100) SURFACES DURING DEPOSITION

We report results of molecular-dynamics simulations of metal-depositio n-induced exchange on fee (100) metal surfaces. In these simulations, the adsorption energy facilitates nonthermal ''transient exchange'' be tween an adatom and a substrate atom by significantly heating a local surface zone around the impact site. Detailed analysis of the dynamics of the deposition-induced exchange mechanism reveals an unexpected mo mentum effect, which influences the degree of transient exchange. When adatoms are heavier than the substrate atoms, exploitation of the tem porarily hot deposition zone is maximized. In contrast, adatoms that a re lighter than the substrate recoil from the surface upon impact, all owing the local impact zone to cool before the adatom has a second cha nce at exchange. Thus transient exchange is somewhat inhibited.