Analysis of photoluminescence from solubilized single-walled carbon nanotubes

The functional form of the photoluminescence (PL) line shape from individual single-walled carbon nanotube (SWNT) species is found to contain a significant Lorentzian component and the Stokes shift is observed to be very small (<80. 3em{0ex}meV), which suggests an excitonic dephasing mechanism that is largely decoupled from surrounding solvent and surfactant molecules. The PL quantum yield (PLQY) of two SWNT species is determined to be 510^-4, and it is suggested that this is lower than the ``true'' value due to quenching of the PL in bundles by metallic tubes. Time-resolved PL measurements reveal a dominant, luminescence lifetime component of 1300. 3em{0ex}ps that, when combined with a predicted natural radiative lifetime of 200. 3em{0ex}ns, suggests that the true PLQY is 6. 510^-3. Finally, deconvoluted PL excitation spectra are produced for eight SWNT species, and the appearance of a higher-energy excitonic subband is discussed.