Purification of single-walled carbon nanotubes generated in helium ambient gas atmosphere with arc-burning apparatus by utilizing mono-dispersion technique.

Raw soot containing single-walled carbon nanotubes (SWNTs), generated with arc-burning apparatus in helium gas atmosphere, was dispersed in 1 wt% sodium cholate (SC)/D2O solution. This solution was then used for successive ultracentrifugation procedure. After ultracentrifugation, UV-VIS and Raman spectra of the supernatant of the solution were investigated. The obtained spectra demonstrate that SWNTs generated with arc-burning method can be well mono-dispersed in surfactant solution, even though large amount of carbonaceous impurities were also included in the raw soot. This finding indicates that mono-dispersion technique can also be applied as the purification procedure for the raw soot including SWNTs of poor quality. Also, it was found that, although the yield of empty fullerenes (as byproduct) decreases as the helium gas pressure increases, that of SWNTs still increases, and shows a maximum at higher pressure. The diameter distribution of semi-conductive SWNTs included in the soot was compared with that generated in nitrogen atmosphere, based on the experimental results obtained by utilizing fluorescence mapping technique to mono-dispersed solutions.