Qualitative detection and quantitative determination of single-walled carbon nanotubes in mixtures of carbon nanotubes with a portable Raman spectrometer.

The main aim of this work is to develop a one-step method for the characterization of mixtures of single- and multi-walled carbon nanotubes using a simple and inexpensive tool, a portable Raman spectrometer. In order to overcome the problem of heat dissipation in solid samples, the suitability of three surfactants-SDS, Triton X-100 and CTAB-to disperse nanotubes has been evaluated. A systematic study of the wavelength and relative intensity of the D and G bands has been carried out with six samples of multiwalled carbon nanotubes (MWNTs) and one of single-walled carbon nanotubes (SWNTs) dispersed in these surfactants, and this has been compared with solid samples. Finally, the possibility has been demonstrated to identify and (semi)quantify the presence of SWNTs in a mixture containing MWNTs.