The Ratio Problem in Single Carbon Nanotube Fluorescence Spectroscopy

TL;DR

This paper addresses discrepancies in fluorescence spectroscopy measurements of single carbon nanotubes by developing a theory of electron-hole interactions, explaining deviations from simple band theory and deriving exciton energies.

Contribution

It introduces a novel theoretical framework for electron-hole interactions in nanotubes, explaining experimental deviations and providing analytic expressions for exciton energies.

Findings

Derived analytic expressions for exciton energies and lineshapes.

Compared theory with experiments to estimate electron-hole interaction strength.

Resolved the 'ratio problem' in nanotube fluorescence spectroscopy.

Abstract

The electronic bandgaps measured in fluorescence spectroscopy on individual single wall carbon nanotubes isolated within micelles show signficant deviations from the predictions of one electron band theory. We resolve this problem by developing a theory of the electron hole interaction in the photoexcited states. The one dimensional character and tubular structure introduce a novel relaxation pathway for carriers photoexcited above the fundamental band edge. Analytic expression for the energies and lineshapes of higher subband excitons are derived, and a comparison with experiment is used to extract the value of the screened electron hole interaction.