TYPES OF NANOTUBES

Carbon nanotubes are basically sheets of graphite rolled up into a tube as shown in this figure. Hence, the hexagonal two dimensional lattice of graphite is mapped on a one-dimensional cylinder of radius R with various helicities characterized by the rolling vectors (n,m).

(n,0) zigzag nanotube

(n,n) armchair nanotube

(n,m) chiral nanotube

An atomically resolved image of a chiral nanotube as observed in STM experiments. Measuring chirality and the diameter (i.e. height) of the nanotube, one can uniquely characterize the nanotube under study.