Influence of surface roughness on adsorbate mobility

Field-emission fluctuations of the coadsorption system W(112)Ni-K were investigated by the cross-correlation technique in two perpendicular crystallographic directions at various temperatures. In- and cross-channel movements show a considerable reduction of _max which is the time delay corresponding to the cross-correlation function maximum with increasing Ni coverage at a constant potassium probe concentration. _max, its activation energy and the signal velocity are discussed in terms of the well-known W(112)Ni surface structure.