The migration of individual Pt adatoms, and clusters of 2 to 6 atoms, on the (100) surface of Rh was investigated by means of field ion microscopy. The mode of diffusion of adatoms and clusters was deduced to be that of conventional site-to-site hopping. Single adatoms and dimers migrated, at 314 to 346K, according to:

D (cm2/s) = 0.002 exp[-0.92(eV)/kT]

Trimers and tetramers, which were more stable as 1-dimensional chains than as 2-dimensional islands (as well as pentamers, which were equally stable as chains or islands), all diffused with the same activation energy of 1.03eV. Hexamers, which were more stable as islands than as chains, migrated with the somewhat higher activation energy of 1.16eV.

G.L.Kellogg: Applied Surface Science, 1993, 67, 134-41