(a) Raman spectrum of the as-received SWCNT thin film with the RBM at 164 cm⁻¹ and G and D peaks at 1590 cm⁻¹ and 1322 cm⁻¹, respectively. Inset: detailed view of the G and the D peaks of the as-received SWCNT thin film. (b) The G and D peaks of the drop-casted SWCNTs from the 60 μg/mL NMP dispersions that were sonicated for 3 minutes (red curve), 12 minutes (blue curve), and 30 minutes (green curve). Inset: detailed view of the D peaks. (c) The decrease in the / ratio of the SWCNTs from the 60 μg/mL NMP dispersions with increasing sonication energy input. The / ratio of the as-received SWCNT sample is plotted at zero sonication energy. The / ratio was determined by measuring the peak heights of the G and the D peaks, respectively, with respect to the baseline.