Pinning of size-selected gold and nickel nanoclusters on graphite

Size-selected gold and nickel nanoclusters are of interest from an electronic, catalytic, and biological point of view. These applications require the deposition of the clusters on a surface, and a key challenge is to retain the cluster size. Here controlled energy impact is used to immobilize the size-selected clusters on the graphite surface at room temperature. The threshold energy for pinning of ionized Au(N) (N=20-100) and Ni(N) (N=10-300) clusters, over the impact energy range 350-2000 eV, is shown by scanning tunneling microscopy to scale with the cluster mass. This behavior is consistent with a previous study of silver clusters and demonstrates the more general applicability of the cluster pinning model.