Direct observation of misfit dislocation glide on surfaces

Using scanning tunneling microscopy we have observed thermally induced disl ocation glide in monolayer Cu films on Ru(0001) at room temperature. The mo tion is governed by a Peierls barrier that depends on the detailed structur e of the dislocations, in particular upon whether the threading dislocation s that terminate them are dissociated or not. Calculations based on the Fre nkel-Kontorova model reproduce the threading dislocation structure and prov ide estimates of the Peierls barrier and dislocation stiffness which are co nsistent with experiment.