Direct observation of Born-Oppenheimer approximation breakdown in carbon nanotubes.
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.
Bushmaker
Adam W
AW
Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089, USA.
Deshpande
Vikram V
VV
Hsieh
Scott
S
Bockrath
Marc W
MW
Cronin
Stephen B
SB