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

TL;DR

This study demonstrates large-amplitude coherent phonon oscillations in single-walled carbon nanotubes excited via the lowest-energy interband transition, revealing new non-resonant RBMs linked to strong exciton-phonon coupling.

Contribution

It reports the first observation of resonant coherent phonons excited through E11 transitions and identifies non-resonant RBMs caused by multi-phonon replicas in carbon nanotubes.

Findings

Large-amplitude RBMs observed at E11 excitation

Comparable intensities for different (n-m) mod 3 nanotubes

Non-resonant RBMs linked to exciton-phonon coupling

Abstract

We have observed large-amplitude coherent phonon oscillations of radial breathing modes (RBMs) in single-walled carbon nanotubes excited through the lowest-energy (E11) interband transitions. In contrast to the previously-studied coherent phonons excited through higher-energy (E22) transitions, these RBMs show comparable intensities between (n-m) mod 3 = 1 and -1 nanotubes. We also find novel non-resonantly excited RBMs over an excitation range of ~300 meV above the E11 transition, which we attribute to multi-phonon replicas arising from strong exciton-phonon coupling.