Fig. 4

a Raman spectra of the SDS-dispersed SWCNTs after 2-fold dilution in 1 wt% solutions of different surfactants with or without NaSCN. The final solutions contain 0.5 wt% SDS, 0.5 wt% each surfactant and 0 or 12.5 mM NaSCN. The spectra are presented relative to the intensity at 236 cm⁻¹ for the original sample, which was diluted twofold in 1 wt% SDS solution. b Chemical structures of DOC and SC