Gold clusters deposited on highly oriented pyrolytic graphite by pulse laser ablation and liquid metal ion source

We compare the shape and size distribution of supported Au clusters on highly oriented pyrolytic graphite prepared by two kinds of cluster beam techniques, liquid metal ion source and pulsed laser ablation. Scanning tunneling microscopy was applied in air to give topographic images of supported Au clusters. The liquid metal ion source technique gives rise to the quasi-two-di-mensional supported Au clusters with a narrow size distribution centered at 5.3 nm at the low coverage, which is explained by a high growth rate at the cluster periphery, resulting from the large diffusion of metallic atoms on the graphite surface. In contrast, the laser ablation technique yields the three-dimensional and smaller clusters formed by solidifying the incident hot Au clusters onto the substrate during the laser ablating process.