Tip-triggered Thermal Cascade Manipulation of Magic Number Gold-Fullerene Clusters in the Scanning Tunnelling Microscope

Abstract

We demonstrate cascade manipulation between magic number gold-fullerene hybrid clusters by channelling thermal energy into a specific reaction pathway with a trigger from the tip of a scanning tunnelling microscope (STM). The (C-60)(m)-Au-n clusters, formed via self-assembly on the Au(111) surface, consist of n Au atoms and m C-60 molecules; the three smallest stable clusters are (C-60)(7)-Au-19, (C-60)(10)-Au-35, and (C-60)(12)-Au-49. The manipulation cascade was initiated by driving the STM tip into the cluster followed by tip retraction. Temporary, partial fragmentation of the cluster was followed by reorganization. Self-selection of the correct numbers of Au atoms and C-60 molecules led to the formation of the next magic number cluster. This cascade manipulation is efficient and facile with an extremely high selectivity. It offers a way to perform on-surface tailoring of atomic and molecular clusters by harnessing thermal energy, which is known as the principal enemy of the quest to achieve ultimate structural control with the STM.