The escape of Pt from (111) Pt islands was studied via field ion microscopy in order to obtain a direct understanding of the atomic events. No effective barrier to the escape of Pt clusters that were larger than dimers was found at step edges, but the incorporation of individual adatoms was more effective at low temperatures. The additional step-edge barrier was estimated to be 0.06eV from the temperature-dependence of the rate of atom disappearance from Pt(111) islands. This value was quite small when compared with the diffusion barrier of 0.26eV, and contrasted sharply with the predictions of growth experiments. The diffusivity of Pt pentamers on (111) surfaces (figure 18) could be described by:

D (cm2/s) = 1.8 x 10-2 exp[-0.78(eV)/kT]

Step-Edge Barriers on Pt(111): an Atomistic View. K.Kyuno, G.Ehrlich: Physical Review Letters, 1998, 81[25], 5592-5

Figure 18

Diffusivity of Pt Pentamers on the (111) Surface of Pt