Figure 5: Raman spectra from several sp2 nanocarbons. From top to bottom: crystalline monolayer graphene, highly oriented pyrolytic graphite (HOPG), single-wall carbon nanotubes (SWNT) bundle sample (notice the presence of the RBMs at low frequencies), damaged graphene (notice the appearance of disorder-induced peaks), single wall carbon nanohorns (SWNHs), and hydrogenated amorphous carbon. Some Raman peaks are labeled in a few of the spectra [2].