We find that the optical properties of carbon nanotubes reflect remarkably strong effects of exciton-phonon coupling. Tight-binding calculations show that a significant fraction of the spectral weight of the absorption peak is transferred to a distinct exciton+phonon sideband, which is peaked at around 200 meV above the main absorption peak. This sideband provides a distinctive signature of the excitonic character of the optical transition. The exciton-phonon coupling is reflected in a dynamical structural distortion, which contributes a binding energy of up to 100 meV. The distortion is surprisingly long-ranged, and is strongly dependent on chirality.
@article{arxiv.cond-mat/0411618,
title = {Exciton-phonon effects in carbon nanotube optical absorption},
author = {Vasili Perebeinos and J. Tersoff and Phaedon Avouris},
journal= {arXiv preprint arXiv:cond-mat/0411618},
year = {2009}
}