A field ion microscopic study was made of the mobility of Rh clusters which contained between 2 and 12 atoms and were adsorbed on the (100) plane. It was found that the activation energy for surface diffusion exhibited an oscillatory behavior as a function of cluster size. Compact geometrical structures such as squares and rectangles required a consistently higher activation energy than did structures which had extra atoms at the periphery.

G.L.Kellogg: Physical Review Letters, 1994, 73[13], 1833-6