Abstract
We report a femtosecond midinfrared study of the broadband low-energy response of individually separated (6,5) and (7,5) single-walled carbon nanotubes. Strong photoinduced absorption is observed around 200 meV, whose transition energy, oscillator strength, resonant chirality enhancement, and dynamics manifest the observation of quasi-one-dimensional intraexcitonic transitions. A model of the nanotube cross section agrees well with the signal amplitudes. Our study further reveals saturation of the photoinduced absorption with increasing phase-space filling of the correlated pairs.
- Received 2 November 2009
DOI:https://doi.org/10.1103/PhysRevLett.104.177401
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