Size and packing of fullerenes on C60/C70 crystal surfaces studied by atomic force microscopy

Abstract

Atomic force microscopy was used to image C60/C70 crystal surfaces under ethanol with resolution of single molecules. Spherical and elongated elliptical fullerenes were observed which most likely correspond with C60 respectively C70. Measurements of the maximum diameter for a large number of molecules confirm the presence of two species of fullerenes, one with 9.4 Å, the other with 11.2 Å. The observed ratio C60:C70 is 81:19, in good agreement with spectroscopical data. The molecules are arranged either in hexagonal or cubic packing; in some areas the two arrangements alternate within a few nm. Elongated fullerenes appear to prefer the hexagonal packing.