| Abstract
| - Absorption spectra of single-walled carbon nanotubes (SWNT) dispersed in dimethylformamide (DMF) havebeen recorded in the visible to near-infrared range. Besides broad absorption bands, the spectra show a sharppeak at 5187 cm-1, which has been attributed in the literature to the absorption of semiconducting nanotubeswith a band gap of 0.64 eV [Ausman et al. J. Phys. Chem. B2000, 104, 8911]. On the basis of absorbancemeasurements for samples that show the sharp absorbance peak but do not contain SWNTs, we conclude thatthe origin of the peak at 5187 cm-1 is not due to semiconducting nanotubes but due to water present in theSWNT/DMF suspension. A comparative study of D2O in DMF reproduces a similar peak that is isotope-shifted into the near-infrared.
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