title: Energy of K-momentum dark excitons in carbon nanotubes by optical spectroscopy.
abstract: Phonon sideband optical spectroscopy determines the energy of the dark K-momentum exciton for (6,5) carbon nanotubes. One-phonon sidebands appear in absorption and emission, split by two zone-boundary (K-point) phonons. Their average energy locates the E11 K-momentum exciton 36 meV above the E11 bright level, higher than available theoretical estimates. A model for exciton-phonon coupling shows the absorbance sideband depends sensitively on the K-momentum exciton effective mass and has minimal contributions from zone-center phonons, which dominate the Raman spectra of carbon nanotubes.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: O N
authors.initials: ON
authors.lastname: Torrens
authors.forename: M
authors.initials: M
authors.lastname: Zheng
authors.forename: J M
authors.initials: JM
authors.lastname: Kikkawa