title: Direct observation of Born-Oppenheimer approximation breakdown in carbon nanotubes.
abstract: Raman spectra and electrical conductance of individual, pristine, suspended, metallic single-walled carbon nanotubes are measured under applied gate potentials. The G(-) band is observed to downshift with small applied gate voltages, with the minima occurring at E(F) = +/-(1)/(2)E(phonon), contrary to adiabatic predictions. A subsequent upshift in the Raman frequency at higher gate voltages results in a "W"-shaped Raman shift profile that agrees well with a nonadiabatic phonon renormalization model. This behavior constitutes the first experimental confirmation of the theoretically predicted breakdown of the Born-Oppenheimer approximation in individual single-walled carbon nanotubes.
authors.affiliation: Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA.
authors.forename: Adam W
authors.initials: AW
authors.lastname: Bushmaker
authors.forename: Vikram V
authors.initials: VV
authors.lastname: Deshpande
authors.forename: Scott
authors.initials: S
authors.lastname: Hsieh
authors.forename: Marc W
authors.initials: MW
authors.lastname: Bockrath
authors.forename: Stephen B
authors.initials: SB
authors.lastname: Cronin