The diffusion of highly excited CO molecules on Cu(111) produced by electron attachment in the course of vertical manipulation within a scanning tunneling microscope apparatus was studied at low temperatures. The majority of the excited molecules exhibited a diffusion length of one ad-site only, whereas of the remaining molecules were found more often at the third rather than the second nearest neighbor. This indicated that ballistic (unscattered) movement played an import role in the diffusion process. A Monte Carlo simulation estimated the probability of ballistic movement to be at least 15% per transgressed ad-site.

On the Diffusion of 'Hot' Adsorbates: a Non-Monotonic Distribution of Single Particle Diffusion Lengths for CO/Cu(111). L.Bartels, M.Wolf, G.Meyer, K.H.Rieder: Chemical Physics Letters, 1998, 291[5-6], 573-8