Resonant Coherent Phonon Generation in Single-Walled Carbon Nanotubes through Near-Band-Edge Excitation

We have observed large-amplitude coherent phonon oscillations of radial breathing modes (RBMs) in single-walled carbon nanotubes excited through the lowest-energy (E 11) interband transitions. In contrast to the previously studied coherent phonons excited through higher-energy (E 22) transitions, these RBMs show comparable intensities between (n−m) mod 3 = +1 and −1 nanotubes. We also find the novel observation of RBMs excited over an excitation range of ∼300 meV above the E 11 transition, which we attribute to possible resonance with phonon sidebands of the lowest optical transition, arising from strong exciton−phonon coupling.