Dynamics of Pt adatom and dimers on Pt(110)-(1×2) observed directly by STM

The one-dimensional diffusion of Pt adatoms as well as the formation/dissociation kinetics of Pt dimers in the missing row troughs of the (1×2) reconstructed Pt(110) surface is monitored directly from atomically resolved time-lapsed STM images. For this self-diffusion system, it is found surprisingly that not only jumps between nearest neighbour sites but also long jumps, i.e. jumps between next nearest neighbour sites participate.

The hopping rate for these long jumps is found to follow an Arrhenius dependence on temperature with an activation barrier for diffusion Ed2=0.89eV slightly larger than that for single jumps Ed1=0.81eV. It is found that dimers dissociate with a rate only slightly below that for single atom diffusion.

Using the data obtained for the latter, the formation/dissociation kinetics of Pt dimers in the missing row troughs can be analysed and the binding energy of the Pt dimer is determined to be Eb=0.07eV.