Radial distribution function analysis of spatial atomic correlations in carbon nanotubes

This paper reports on structural characterisation of single and multi-wall carbon nanotubes, synthesised by catalytic decomposition of methane and acetylene, by wide-angle pulsed neutron scattering, extended up to a maximum scattering vector Of Q(max)= 60 Angstrom(-1). The intensity data were converted to real space via the Fourier transform yielding the radial distribution functions (RDFs) with the resolution of approximately 0.1 Angstrom. The structural parameters defining the interatomic distances, their standard deviations and the coordination numbers have been derived from the experimental data by a curve-fitting method based on a least-squares algorithm. The nearest-neighbour carbon-carbon distance 1.41 Angstrom is practically the same as that of graphite and clearly shorter than the value of 1.44 Angstrom found for fullerenes. The results provide experimental evidence for the hexagonal structure within a single tubule and turbostratic stacking of successive tubules. The derived RDFs can be fitted using a model based on a hexagonal network with disorder increasing with square root of the interatomic distance. (C) 2003 Elsevier B.V. All rights reserved.