The non-equilibrium diffusion of highly hyper-thermal atoms, which resulted from the dissociative adsorption of a di-atomic molecule, was investigated by using molecular dynamics and an effective-medium model potential. The parameters of the potential were chosen so as to describe O2 on Al(111), and the simulation results were compared with scanning tunnelling microscopic measurements of that system. It was found that the transient displacement along the surface was about an order of magnitude larger than the distance to the nearest adsorption site. This distance was limited mainly by the rapid randomization of adsorbate motion, rather than by the rate of energy transfer to the substrate degrees of freedom.

C.Engdahl, G.Wahnström: Surface Science, 1994, 312[3], 429-40