SUBMONOLAYER SCALING DUE TO COALESCENCE OF SUBNANOMETRIC COPPER CLUSTERS ON ALUMINA

The dynamic scaling of cluster size distribution in submonolayer Volme r-Weber growth is demonstrated in the case of copper deposited on alum ina, in the subnanometric size range. This scaling is explained by the coalescence of copper clusters, as in breath figures due to the conde nsation of liquid droplets. We show that extended x-ray absorption fin e-structure spectroscopy at the Cu K edge can be used to determine, as a function of deposition time, the growth law of the mean cluster siz e, in the radius range 2-10 Angstrom, This growth law, which can be fi tted by a power law with an exponent 1.2, is fairly well reproduced by a purely stochastic coalescence model.