MORPHOLOGY AND ORIENTATIONAL DISORDER OF C-70 SINGLE-CRYSTALS

C-70 Single crystals, free from solvent contamination, were grown via vapor phase transport technique. The (0001) face of the C-70 crystal was imaged with Atomic Force Microscopy (AFM) under ambient atmosphere. Low-resolution images of a freshly prepared crystal revealed well-ordered faceted regions with multiple terraces extending over a region of several hundred square nanometers. The terraced structure in the images indicates that the crystals formed as a layer growth. In the high-resolution images, C-70 molecules were resolved in a hexagonal close packed (hcp) structure with an average center-to-center distance of 10.5 +/- 0.5 Angstrom. After one month's exposure to the ambient atmosphere, the molecules rearranged into a mixed structure consisting of hcp and face centered cubic (fee) regions.