Surface enhanced Raman scattering from multiwalled carbon nanotubes at low temperatures

We report temperature dependent Raman spectra of multiwalled carbon nanotubes deposited as dilute dispersions on surface enhanced Raman scattering active substrate. At low temperature, i.e, below 30 K both the tangential and the disorder mode acquire additional spectral features which are otherwise absent in the room temperature spectra. Further, we observe that the surface enhancement effect is more for modes involving motion of atoms in the direction perpendicular to the substrate which is consistent with the surface selection rules. These experiments provide access to certain spectral features of multiwalled carbon nanotubes which are otherwise very difficult to see.