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

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 (C60)m-Aun clusters, formed via self-assembly on the Au(111) surface, consist of n Au atoms and m C60 molecules; the three smallest stable clusters are (C60)7-Au19, (C60)10-Au35, and (C60)12-Au49. 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 C60 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.