Surface energetics from analysis of nucleation data in metal homoepitaxy

Analysis of experimental data on nucleation on surfaces is far from bei:ng a routine procedure. This is illustrated on the example of 2D nucleation on Cu(001) (Zuo et al. Phys. Rev. Lett. 72, 3064 (1994); Durr et al. Surf. Sci. 328, L517 (1995)). The reinterpretation of the data leads to the result that the observed change of the slope of the Arrhenius plot of the island separation can be explained by a change of the mechanism of diffusion from a concerted substitutional mechanism at low temperatures with an energy barrier of 0.24 eV to a bridge-hopping mechanism at higher temperatures with an energy barrier of 0.45 eV, rather than by a change in the number of atoms in the critical nucleus from 1 to 3.