| Fullerene nanotubes were suspended as individuals in aqueous sodium dodecylsulfate (SDS) by sonication and ultra centrifugation. Ultra centrifugation was found to remove bundles of nanotubes and metal catalyst particles, since they have a density greater than water. The supernatant contained individual fullerene nanotubes encapsulated by a SDS micelle. SWNTs suspended in an SDS micelle could be further stabilized by associating the nanotube with a polymer and removing the surfactant. Polymer-wrapped SWNTs could be used in various separation techniques. The absorption spectrum (190nm–1800nm) of these individual tubes was much better resolved when compared to all previous methods. These earlier methods of suspending nanotubes contained large numbers of bundles. The individualized semiconducting nanotubes were found to have structured fluorescence in the near-infrared. This fluorescence was not previously observed, because of quenching by metallic tubes in bundles. |
