title: Structural dependence of excitonic optical transitions and band-gap energies in carbon nanotubes.
abstract: The optical transitions of semiconducting carbon nanotubes have been ascribed to excitons. Here we use two-photon excitation spectroscopy to measure exciton binding energies, as well as band-gap energies, in a range of individual species of semiconducting SWNTs. Exciton binding energies are large and vary inversely with nanotube diameter, as predicted by theory. Band-gap energies are significantly blue-shifted from values predicted by tight-binding calculations.
authors.affiliation: Department of Chemistry, Columbia University, 3000 Broadway, New York 10027, USA. gd2012@columbia.edu
authors.forename: Gordana
authors.initials: G
authors.lastname: Dukovic
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.forename: Daohua
authors.initials: D
authors.lastname: Song
authors.forename: Matthew Y
authors.initials: MY
authors.lastname: Sfeir
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: Louis E
authors.initials: LE
authors.lastname: Brus