Absorption spectra of high purity metallic and semiconducting single-walled carbon nanotube thin films in a broad frequency region

Absorption spectra of high purity metallic and semiconducting single-walled carbon nanotubes have been measured from THz to UV region. The broad absorption band around 100-1000 cm
^-1
of the metallic sample can correspond to the optical transition between small energy gap in “metallic” nanotubes.