The effect of bundling on the G′ Raman band of single-walled carbon nanotubes

The behaviour of the Raman G' band of solubilized SWCNTs in aqueous solution is investigated with respect to ultrasonication time, surfactant type and centrifugation. The linewidth of the high frequency component of the G' band is shown to correlate with the degree of bundling in the solution. In particular, the linewidths of all dispersions decrease as a consequence of subsequent centrifugation, reaching values characteristic of individual SWCNTs (30 cm(-1)). These results correlate well with the observed changes of the radial breathing modes. Further, using this approach an evaluation of the extent of debundling SWCNTs using surfactant solutions (sodium dodecylbenzenesulfonate and sodium dodecyl sulfate) and deoxyribonucleic acids with respect to surfactant concentration, ultrasonication time and centrifugation was performed.