Figure 3.

Structural quality of carbon nanotube samples. I_D/I_G band intensity ratios were determined from the Raman spectra of all single-walled and multi-walled carbon nanotube samples. A lower I_D/I_G ratio (shorter bars) indicates fewer defects and therefore higher structural quality. Due to the limitations of this method, the higher observed values for the multi-walled carbon nanotube samples is not necessarily indicative of a higher number of defects.

Abbreviations: SWNT, single-walled carbon nanotubes; MWNT, multi-walled carbon nanotubes.