How accurate can the determination of chiral indices of carbon nanotubes be?

We present a general and systematic method for determining the chiral indices of carbon nanotubes. This method relies on the semi-quantitative analysis of experimental selected area diffraction pattern intensities, together with extensive comparison with kinematic theory. We show how to retrieve the chiral indices of single walled or multiwalled carbon nanotubes, even when their radii are large (up to approximately 40 ?). All theoretical and experimental sources of errors are discussed. By discussing the experimental case of a double-walled carbon nanotube, we show how it is possible to determine the chiral indices of each of its constituant tubes independently, by analyzing parts of the diffraction pattern where the contributions of these tubes do not interfere. Using the parts where all the contributions do interfere, we successfully crosschecked independently the preceding determination. Received 23 December 2003 Published online 7 May 2003