Toward rapid and inexpensive identification of bulk carbon nanotubes

The volume fraction of metallic and semiconducting carbon single-wall nanotubes (SWNTs) has been estimated for purified laser vaporization SWNTs, from an effective medium approximation and the measured spectral responsivity of a LiTaO3 pyroelectric detector covered with SWNT “bucky” paper. The detector spectral responsivity from 600to2000nm is proportional to the expected absorption coefficient of the SWNTs, and variations near 700, 950, and 1750nm correlate with characteristic interband transitions and proportions of SWNTs consistent with 20% metal and 80% semiconductor materials.