Luminescence Decay and the Absorption Cross-Section of Individual Single-Walled Carbon Nanotubes

TL;DR

This study measures the absorption cross-section and analyzes luminescence decay in individual single-walled carbon nanotubes, revealing biexponential decay behavior linked to exciton fine structure.

Contribution

It provides the first direct measurement of absorption cross-section for individual nanotubes and links decay dynamics to exciton fine structure.

Findings

Absorption cross section of 1x10^-17 cm^2 per carbon atom for (6,5) nanotubes.

Biexponential luminescence decay with lifetimes around 45 ps and 250 ps.

Decay behavior attributed to dark and bright exciton states.

Abstract

The absorption cross section of highly luminescent individual single-walled carbon nanotubes is determined using time-resolved and cw luminescence spectroscopy. A mean value of 1x10-17 cm2 per carbon atom is obtained for (6,5) tubes excited at their second optical transition, and corroborated by single tube photothermal absorption measurements. Biexponential luminescence decays are systematically observed, with short and long lifetimes around 45 and 250 ps. This behavior is attributed to the band edge exciton fine structure with a dark level lying a few meV below a bright one.