Authors: R.R. Bacsa, E. Flahaut, Ch. Laurent, A. Peigney, P. Puech and W.S. Bacsa
Affilation: LPST Université Paul Sabatier, France
Pages: 214 - 217
Keywords: nanotubes, carbon, microscopy, light scattering, phonons
Narrow diameter double walled carbon nanotubes can now be grown by the catalytic chemical vapor deposition process with high yield. Double walled carbon nanotubes are the molecular analogs to coaxial cables and they can also be imagined to be used as actuators where the two tubes slide on each other. The outer tube protects the internal tube from its environnement and isolates the electric conductor of sub-nanometer dimension over micrometer long distances. The definition of the environnemnt is particularly important for a systems were a large number of atoms are situated at the surface. It has been recently shown that the coupling of the internal and external tube depends on diameter and is smaller for narrow diameter double walled tubes. Narrow diameter carbon nanotubes are particulary interesting due to their large curvature. While it is still particularly difficult to grow tubes of controlled helicity, inelastic light scattering is a powerful tool to find the helicity of narrow diameter internal tubes. After caracterizing the tubes by scanning and transmission electron microscopy, we have examined the inelastic light scattering spectrum of narrow double walled carbon nanotubes. We observe particularly sharp radial breathing modes and strongly helicity dependent spectral bands in the in-plane phonon frequency range.