Anisotropic Decay Dynamics of Photoexcited Aligned Carbon Nanotube Bundles

TL;DR

This study investigates how the polarization of light affects the ultrafast photoexcited dynamics in aligned carbon nanotube bundles, revealing a previously unobserved slow relaxation process linked to surface plasmons.

Contribution

It provides a quantitative analysis of anisotropic decay dynamics in aligned nanotubes, highlighting polarization-dependent relaxation processes including a novel slow component.

Findings

Perpendicular polarization shows a slow relaxation of 1.0-1.5 ps.

Distinct decay dynamics are observed for different polarizations.

Surface plasmons contribute to the slow relaxation in aligned nanotubes.

Abstract

We have performed polarization-dependent ultrafast pump-probe spectroscopy of a film of aligned single-walled carbon nanotube bundles. By taking into account imperfect nanotube alignment as well as anisotropic absorption cross sections, we quantitatively determined distinctly different photo-bleaching dynamics for polarizations parallel and perpendicular to the tube axis. For perpendicular polarization, we observe a slow (1.0-1.5 ps) relaxation process, previously unobserved in randomly-oriented nanotube bundles. We attribute this slower dynamics to the excitation and relaxation of surface plasmons in the radial direction of the nanotube bundles.