IMAGING C-60 FULLERITE AT 4.5-K BY SCANNING TUNNELING MICROSCOPY

Intramolecular contrast of C60 molecules has been observed by scanning tunneling microscopy at 4.5 K on a C60 fullerite thin film sample. This result provides strong evidence for the freezing of the rotational motion of C60 molecules at low temperatures as recently proposed by refinement analysis of neutron diffraction data. Different intramolecular patterns are observed. Interpretation of these patterns is suggested by assigning them to carbon ring structures of the C60 molecules in various orientations.