The effect of the environment on the electronic properties of single-walled carbon nanotubes

We present optical absorption spectra of single-walled carbon nanotube (SWNT) films obtained after 1-year-long film storage in air and upon heating up to 250$^\circ$C. The results of the investigation show that long-term storage of the SWNTs in normal atmosphere leads to a substantial drop in intensity of optical absorption caused by electronic excitation, which recovers after film heating. The mechanism of changes in the electronic properties of the SWNTs under the influence of environment is discussed.