Survey of Exciton-Phonon Sidebands by Magneto-optical Spectroscopy Using Highly Purified (6,5) Single-walled Carbon Nanotubes

TL;DR

This study uses high-field magneto-optical spectroscopy on purified (6,5) SWNTs to investigate exciton-phonon sidebands, confirming their origin from K-momentum dark excitons and providing precise energy measurements.

Contribution

First high-field magneto-optical analysis of exciton-phonon sidebands in pure (6,5) SWNTs, confirming their origin and quantifying dark exciton energies.

Findings

Sidebands are magnetic field independent.

Sidebands originate from K-momentum dark excitons.

Dark exciton energy is ~21.5 meV above bright excitons.

Abstract

We report the first high-field magneto-optical study on the exciton-phonon sideband of single-walled carbon nanotubes (SWNTs) consisting only of (6,5) species. Both energy and intensity of the observed phonon sideband were found to be independent of the external magnetic field. Comparing with theoretical calculations, we confirmed that these sidebands originate from the optically forbidden K-momentum singlet excitons. Energy of these K-momentum dark excitons was extracted to be ~ 21.5 meV above the bright zero-momentum singlet excitons, in close agreement with recent theoretical predictions and experimentally determined values.