  We report optical separation of metallic and semiconducting single walled
carbon nanotubes of specific diameters from well-dispersed, stable solution.
This phenomenon of optical separation was studied using lamps of different
frequencies across UV, Vis and NIR spectrum. Optically aggregated SWNTs were
separated from the SWNTs remaining dispersed in the solution and characterized
using absorption and Raman spectroscopy. Separated SWNTs distinctly show
enrichment of metallic SWNTs using UV lamp, whereas different diameter of SWNTs
aggregates out depending on the frequency of illumination. Fabricated field
effect transistors based on the separated SWNTs under UV lamp confirms
enrichment of metallic SWNTs in the supernatant where as aggregated SWNTs shows
semiconducting behavior. Spectral changes and electronic (IV) measurements of
our optically separated SWNTs were compared and verified with the reference
solution of pre-separated, pure metallic and semiconducting SWNTs.
