Gold clusters: the role of the ion energy in their formation

Abstract

AbstractThe rapidly growing interest in the deposition of size-selected nanoclusters on surfaces is motivated both by technology and by basic physical questions. Due to their finite size, small particles have totally different material properties compared to their bulk crystalline counterparts. Clusters have been deposited by a monoenergetic, mass-selected ion beam with low energies (10-500 eV) on amorphous carbon substrates, which are used to minimize the influence of surface crystallography and ion-induced structural changes. Gold clusters were deposited as a model system to study the ion energy dependence, the temporal evolution, and the influence of the temperature on the cluster distribution. For impact energies below 100 eV, surface processes dominate the cluster nucleation and growth. If higher energies are used, an increasing number of ions is implanted below the surface and different processes control the cluster formation. When the energy increases above 350 eV, the cluster size drastically drops below 5 nm. The clusters are analysed with different methods such as Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), and X-Ray Photoelectron Spectroscopy (XPS) to determine their size distribution, composition and structure.