Stacking characteristics of graphene shells in carbon nanotubes

Intershell spacings between carbon nanotubes ${\hat{d}}_{002}$ ranging from 3.59 ÅA to 3.62 ÅA, with an uncertainty of ±0.06 ÅA, are deduced by using the in-plane C-C bonding length in the graphene hexagonal network as an internal calibration standard for the digital image analysis of TEM lattice images. These large ${\hat{d}}_{002}$ values imply weak intershell correlation between carbon atoms on adjacent tubules. By using the measured ${\hat{d}}_{002}$ values and the finite number of possible nanotubes, a determination of the chiral vector is made for two shells within a multiwall nanotube. The connection between constraints on ${\hat{d}}_{002}$ and the self-assembly of multilayer carbon nanotubes is discussed.