Purification and characterization of single-wall carbon nanotubes

A purification method has been developed that provides for the removal of metal catalysts and impurity carbon from laser-oven-grown single-wall carbon nanotube (SWNT) material. The oxidation rate of SWNTs in air at elevated temperatures is correlated to the metal content of the sample. Sample purity is documented with SEM, TEM, electron microprobe analysis, Raman, and UV-vis-near-IR. We also note that the relative intensity of the electronic transitions in the near-infrared to the continuum absorption at 400 nm in the UV serves as a useful monitor of the perturbation of the sidewall pi -electron density of SWNTs due to sidewall substitution and/or oxidation.