Purification and characterization of single-wall carbon nanotubes

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