Observation of surface self-diffusion on ice.

To determine the role of surface diffusion on the morphology of ice surfaces we track the evolution with STM of 2D ice-island arrays on the basal surface of ice films on Pt(111) between 115 and 135 K. In contrast with previous measurements at higher temperatures, we find that the evolution is dominated by surface diffusion. The extracted surface self-diffusion coefficient has an activation energy of 0.4+/-0.1 eV, much less than the value previously measured for bulk diffusion.