Determination of time dependence of domain growth by direct observation of small metal clusters

The in situ growth of small gold clusters on amorphous carbon substrates has been measured by direct observation, utilizing high (single-atom) resolution scanning transmission electron microscopy. The time dependence of the width of the distribution of characteristic microscopic spatial frequencies in the samples was seen to obey a power-law behavior, HWHM = (t − t₀)^−a. The exponent measured, a = 0.15 ± 0.06, was in good agreement with scaling theories for domain growth. An excess of single atoms and small clusters was observed at all times, over that predicted by a uniform growth model of clusters. It is suggested that these support single-atom and few-atom cluster migration and activated accretion as important components of cluster growth at all times.