Quantitative assessment of carbon nanotube dispersions by Raman spectroscopy

Aqueous dispersions of single wall carbon nanotubes (C-SWNTs), prepared using different dispersing agents, have been analysed by Raman spectroscopy. Normalising the spectra with respect to the area of the water O–H stretching transition eliminates the effects of photon scattering and absorption on the way through the dispersion, and the dispersions can be assessed quantitatively by comparison of the areas of the carbon nanotube G-band. The normalised G-band areas show linear concentration dependence according to Beer’s law. The influences of different dispersing agents and excitation wavelengths are discussed and the results are compared to the commonly used UV–Visible spectroscopic analysis. The method presented here is semi-quantitative and it is proposed to use the most effective dispersing agent found in this study, sodium dodecylbenzene sulfonate (SDBS), as a benchmark for future dispersion experiments.