Penetration of thin C60 films by metal nanoparticles

Abstract

Metal nanoparticles supported by thin films are important in the fields of molecular electronics, biotechnology and catalysis, among others. Penetration of these nanoparticles through their supporting films can be undesirable in some circumstances but desirable in others, and is often considered to be a diffusive process. Here, we demonstrate a mechanism for the penetration of thin films and other nanoscopic barriers that is different from simple diffusion. Silver clusters that are soft-landed onto a monolayer of C(60) supported by gold sink through the monolayer in a matter of hours. However, the clusters are stable when landed onto two monolayers of C(60) supported on gold, or on one monolayer of C(60) supported on graphite. With backing from atomistic calculations, these results demonstrate that a metallic substrate exerts attractive forces on metallic nanoparticles that are separated from the substrate by a single monolayer.

Catalysis by clusters with precise numbers of atoms

“…Revealing the structural dynamics of a cluster on a surface is crucial to understanding catalytic systems. Another example employs STM to investigate the diffusivity of Au clusters deposited on monolayers of C 60 supported by an Au(111) under-layer 80 .…”

Nanoassemblies of ultrasmall clusters with remarkable activity in carbon dioxide conversion into C1 fuels

“…This step ensures that the clusters do not undergo fragmentation upon landing. 27,28 The substrates were prepared by atomic layer deposition (ALD) of alumina on top of a native oxide of a silicon wafer (SiO 2 /n-type, phosphorusdoped Si (100)), yielding an ∼3 monolayer (ML) thin hydroxylated amorphous alumina film. The clusters of a single size were deposited on the substrate at a surface coverage of 5% of a ML, containing a total of 1.11 × 10 13 Cu 4 clusters on the sample surface, at an estimated average cluster-to-cluster distance of 3 nm.…”

Ultraviolet photoelectron spectroscopy of supported mass selected silver clusters

“…Most of the clusters have a height of 1.4 nm, while a few are bigger, probably due to coalescence, because the coverage is already too large in this area. Even though this height is slightly larger than the height measured for Ag 55 clusters on top of a C 60 film 29, we expect that the clusters penetrate the Xe film. We observed that for clusters produced by buffer layer assisted growth on Xe films a film thickness larger than 10 ML is needed to separate the clusters from the substrate, and different to the quite stable STM image in Fig.…”