Helicity and packing of single-walled carbon nanotubes studied by electron nanodiffraction

Electron nanodiffraction patterns from raft-like bundles of single-walled carbon nanotubes have been obtained to analyze the helicity distribution and the packing of the tubules. In most cases, the helical angles were found to be quite evenly distributed, ranging from the zigzag structure of 0 degrees helicity to the armchair structure of 30 degrees helicity. Examples of preferred helicities were encountered occasionally, such as bundles of tubules of almost single-helicity, corresponding to the armchair structure. The lattice constant of the hexagonally packed bundles varied and two example values were determined to be 1.64 nm and 1.71 nm, respectively.