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.