Surface diffusion of K on Pd 111 studied by photoemission electron microscopy

Surface diffusion of K atoms on Pd 111 has been measured by photoemission electron microscopy in a wide temperature range (150-450 K) for coverages η < 0.04. Two contributions to the diffusion process have been identified showing different rates and temperature dependences; both are determined by the surface microtopography. In the light of these result the discrepancy between microscopic and macroscopic diffusion constants can be understood.