Carbon Nanotubes (Raman Spectroscopy)

Recently, we have considered the Raman spectra of graphene and graphene oxide to understand the number of lines and the line shapes to be used for decomposing the spectra. Here we review some literature about the Raman spectroscopy of carbon nanotubes, focusing especially on the line shapes. As shown by literature, the Raman spectra are able of giving information on the nature of nanotubes (metallic or semiconducting) and if they are single- or multi-walled structures. We will find that the Raman spectroscopy is able of investigating even a single nanotube. It will be stressed the role of curvature in breaking the symmetry of carbon layers, to produce the observed Raman bands. In particular, the existence of a Breit-Wigner-Fano line will be investigated. We have encountered the BWF line in a previous review about molybdenum disulfide MoS2 Raman spectroscopy.