Electron diffraction study of small bundles of single-wall carbon nanotubes with unique helicity

The selected-area electron diffraction technique has been used to investigate the structure of bundles of single-wall carbon nanotubes synthesized by the catalytic chemical vapor deposition method. The helicity and lattice packing of the single-wall carbon nanotubes within the bundles have been deduced from the experimental diffraction patterns on the basis of the geometry of the reciprocal space of carbon nanotubes and computer simulations based on the kinematical theory. We show that a precise helicity can be found within a given small bundle. We attribute this selectivity to the small number of nanotubes (20-30) in the bundles.