Ring of C60 polymers formed by electron or hole injection from a scanning tunneling microscope tip

Carrier (electron or hole) injection from a scanning tunneling microscope tip causes various surface modifications on the molecular scale. We report that injection into C-60 close-packed layers forms a ring-shaped distribution of C-60 polymers. This can be explained on the basis of the radial propagation and energy dissipation of carriers. Subsequent electron or hole injections enlarge the ring, showing that both carriers can induce both polymerization and depolymerization. Furthermore, we demonstrate visualization of carrier scattering by injecting carriers into C-60 layers with grain boundaries.