Exciton-phonon Bound Complex in Single-walled Carbon Nanotubes Revealed by High-field Magneto-optical Spectroscopy

TL;DR

This study uses high-field magneto-optical spectroscopy to reveal that phonon sidebands in single-walled carbon nanotubes originate from dark K-momentum singlet excitons, providing insights into exciton-phonon interactions and excitonic energy ordering.

Contribution

It demonstrates that phonon sidebands are from dark K-momentum singlet excitons and clarifies their energy levels relative to bright excitons in specific nanotubes.

Findings

Phonon sidebands are unaffected by magnetic fields up to 52 T.

Dark K-momentum singlet excitons are responsible for phonon sidebands.

Energy levels of these excitons are estimated at ~21.5 and ~37.3 meV above bright excitons.

Abstract

High-field magneto-optical spectroscopy was conducted on highly-selected chiral (6,5) specific single-walled carbon nanotubes. Spectra of phonon sidebands in both 1st and 2nd sub-bands were observed to be unchanged by the application of an external magnetic field up to 52 T. Our analyses led to the conclusion that both phonon sidebands in respective sub-band originate from the dark K-momentum singlet (D-K-S) excitons. Moreover, while the relative ordering between the bandedge bright exciton and its zero-momentum anti-bonding counterpart was found to be opposite for the 1st and 2nd sub-bands, the relative ordering between the D-K-S exciton and the band-edge bright exciton was clarified to be the same for both sub-bands. Energy of these D-K-S excitons was estimated to be ~ 21.5 and ~ 37.3 meV above the band-edge bright exciton for the 1st and 2nd sub-bands, respectively.