FTIR-luminescence mapping of dispersed single-walled carbon nanotubes

We have applied the FTIR-luminescence/FT-Raman technique to map the near-infrared photoluminescence?(PL) of water?surfactant dispersions of single-walled carbon nanotubes (SWNTs) in broad excitation (250?1500?nm) and emission (800?1700?nm) ranges. The excitation wavelength was scanned by using the monochromatized light of standard xenon and tungsten halogen lamps. The PL maps are presented for SWNTs with a mean diameter of ~1.3?nm prepared by the pulsed laser vaporization method. When dispersed by powerful ultrasonic agitation and separated by ultracentrifugation, these nanotubes show structured absorption bands and a PL quantum yield as high as ~10-3. This indicates a large fraction of individual nanotubes in the dispersion. Electronic interband transition energies of nanotubes derived from the PL data correspond reasonably to the energies calculated in the modified tight-binding model of Ding et al.