Polymer ring formation by electron/hole injection from an STM tip into a C₆₀ close-packed layer

Polymerization and depolymerization of C₆₀ molecules are induced by charge carrier injection from a scanning tunneling microscope tip into C₆₀ close-packed layers. These reactions are hard to be achieved at single molecular precision because of a spatial spread of injected carriers. We report that the carrier-spreading effect produces a ring-shaped distribution of C₆₀ polymers around the carrier injection point. Formation of the polymer ring of C₆₀ is explained by energy dissipation of spreading carriers. Therefore, the polymer ring can be recognized as a direct reflection of carrier propagation. Subsequent electron or hole injections enlarge the ring. This result shows that both electrons and holes can induce both polymerization and depolymerization of C₆₀ molecules.