from transmission electron microscopy (TEM) investigations[@Reim89; @LL02] concerning the time- and temperature-dependent behavior of Au clusters deposited by laser ablation technique on amorphous-carbon (a-C) films. The reasons to choose an amorphous substrate are threefold. Firstly, the non-crystalline structure of the substrate allows for the visualization of the crystal structure of the adsorbed clusters in high resolution TEM (HRTEM) experiments. Secondly, amorphous carbon is mechanically much more stable than highly oriented pyrolytic graphite (HOPG) and consequently much more suited for technical applications. Thirdly, as opposed to the conductor HOPG, amorphous carbon is semi-conducting [@Robe86; @RFG04] and as such is expected to be less influential on the electronic properties of the adsorbate. Furthermore, our observations were made on samples that were stored under normal atmosphere for several months enhancing their relevance for possible technical applications.

The central observation reported in this paper is the formation of islands on a time scale of several months after the deposition of the Au adsorbate. Typical TEM images of the samples are shown in Fig. \[expfig1\]. Panel (a) is a sample one day after its preparation. The inset shows the size distribution of the clusters. Clusters smaller than 1 nm in diameter cannot be resolved unambiguously 