Scanning probe microscopy investigation of gold clusters deposited on atomically flat substrates

Abstract

We systematically studied the influence of the substrate on the shape, mobility, and stability of deposited gold clusters. The Aun clusters were produced in a laser vaporization source and deposited with low kinetic energy (~0.4 eV/atom) on atomically flat substrates (graphite, mica, and gold and silver films on mica) under UHV conditions. Their size distribution is probed with time-of-flight mass spectrometry and ranges from dimers to several hundreds of atoms. Scanning probe microscopy is used to characterize the deposited clusters and the formation of islands by cluster aggregation. On all substrates, Aun islands can be clearly distinguished and the islands are flattened despite the small impact energy. The shape and size of the island configurations are strongly system dependent. Gold clusters deposited on Au(111) and Ag(111) films grown on mica do not aggregate, but deform due to strong cluster–substrate interactions. The clusters tend to grow epitaxially on these surfaces. On graphite and on mica, deposited clusters do diffuse and aggregate. On the graphite surface, large ramified islands are formed by juxtaposition of small islands and trapping of the clusters at the step edges. On the other hand, the diffusion of the clusters on mica results in a total coalescence of the Aun clusters into compact islands.

Pinning of size-selected gold and nickel nanoclusters on graphite

“…Inspection of the STM figures indicates at least an order of magnitude higher cluster density in the work of Ref. 13. We suggest that at low density the mobile clusters diffuse to defect sites such as step edges and/or that isolated clusters on the terraces are easily displaced by the STM tip.…”

Confinement of surface state electrons in self-organized Co islands on Au(111)

“…We refer to Vandamme et al [23] for the deposition parameters. The Au(111) surfaces are cleaned in situ by repeated cycles of Ar consist of atomically flat regions with dimensions up to 500 × 500 nm 2 .…”

Lattice dynamics in Sn nanoislands and cluster-assembled films

“…A more detailed description of this setup can be found elsewhere 47 . The gas-phase Sn clusters have a size distribution centered at a diameter of about 3.1 nm with a full width at half maximum of 1.1 nm, see Fig.…”