Structural evolution of gas-phase coinage metal clusters in thiolate self-assembled monolayers on Au

Metallization of organic surfaces is important especially for applications in molecular electronics. It can be realized by different means, one promising albeit less studied method being gas-phase deposition of metal clusters. Here, we report on the interactions of gas-phase Cu, Ag, and Au clusters with n-dodecanethiolate self-assembled monolayers (SAMs) on Au substrate. The morphology and composition of the deposited clusters and their impact on the interface structure of the SAM/Au substrate were investigated using scanning tunneling microscopy. The chemical and physical interactions between the clusters and thiolates were characterized using X-ray photoelectron spectroscopy. The Au clusters are found to penetrate through the monolayer as a whole and partially retain their spherical geometry, whereas atom-by-atom diffusion and/or defect-mediated penetration are proposed for the Cu and Ag clusters.