Influence of excited electron lifetimes on the electronic structure of carbon nanotubes

TL;DR

This study investigates how the lifetimes of excited electrons in single-wall carbon nanotubes vary with energy, revealing rapid decay at higher energies that impacts the electronic density of states and spectral features.

Contribution

It provides the first detailed measurement of excited electron lifetimes in carbon nanotubes across a broad energy range using femtosecond photoemission.

Findings

Electron lifetimes decrease from 130 fs at 0.2 eV to less than 20 fs above 1.5 eV.

Shorter lifetimes at higher energies cause broadening of van Hove singularities.

Electron dynamics significantly influence the electronic structure and spectral properties.

Abstract

We have studied the dynamics of electrons in single wall carbon nanotubes using femtosecond time-resolved photoemission. The lifetime of electrons excited to the pi* bands is found to decrease continuously from 130 fs at 0.2 eV down to less than 20 fs at energies above 1.5 eV with respect to the Fermi level. This should lead to a significant lifetime--induced broadening of the characteristic van Hove singularities in the nanotube DOS.