title: Longitudinal optical phonons in metallic and semiconducting carbon nanotubes.
abstract: We analyze the high-energy Raman modes, G+ and G-, in a pair of one metallic and one semiconducting nanotubes. By combining Rayleigh scattering with Raman resonance profiles of the radial breathing mode and the high-energy modes, we show that the observed G- and G+ peaks can originate from longitudinal optical phonons of different tubes. The G- peak is the longitudinal mode of the metallic tube; it is broadened and downshifted due to strong electron-phonon coupling in the metallic nanotube. The G+ peak is due to the longitudinal mode in the semiconducting tube. This result resolves an ongoing debate in the literature.
authors.affiliation: Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstrasse 36, 10623 Berlin, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Fouquet
authors.forename: Hagen
authors.initials: H
authors.lastname: Telg
authors.forename: Janina
authors.initials: J
authors.lastname: Maultzsch
authors.forename: Yang
authors.initials: Y
authors.lastname: Wu
authors.forename: Bhupesh
authors.initials: B
authors.lastname: Chandra
authors.forename: J
authors.initials: J
authors.lastname: Hone
authors.forename: Tony F
authors.initials: TF
authors.lastname: Heinz
authors.forename: C
authors.initials: C
authors.lastname: Thomsen