Narrow diameter double-wall carbon nanotubes: synthesis, electron microscopy and inelastic light scattering

Double-wall carbon nanotubes are the molecular analogues to coaxial cables. Narrow diameter double-walled carbon nanotubes ( DWNTs) have been obtained by catalytic chemical vapour deposition process with high yield and characterized by scanning and transmission electron microscopy. We examine the inelastic light scattering spectrum of mostly DWNTs with internal tubes of subnanometre diameter. We observe particularly narrow radial breathing modes corresponding to the internal tubes of diameter less than 0.7 nm of double-walled tubes. The D band is found to be strongly helicity dependent and the tangential modes in narrow diameter DWNTs are found to be often down-shifted.