Reflectance spectra of individual single-walled carbon nanotubes

We report backscattering spectroscopic measurements on individual single-walled carbon nanotubes (SWNTs). The reflectance spectra show geometry-dependent resonant peaks corresponding to optical transitions between Van Hove singularities in the SWNTs' joint density of states. All nanotubes display certain colours as their reflectance spectra demonstrate strong energy dependence. This approach was proved to be an effective tool for probing the geometric structures and optical properties of individual SWNTs.