Alignment Dynamics of Single-Walled Carbon Nanotubes in Pulsed Ultrahigh Magnetic Fields

TL;DR

This study investigates how single-walled carbon nanotubes align dynamically in pulsed ultrahigh magnetic fields using linear dichroism spectroscopy, revealing the influence of various factors and developing a theoretical model.

Contribution

The paper introduces a new experimental approach to measure SWNT alignment in pulsed high magnetic fields and presents a theoretical model explaining the alignment behavior.

Findings

SWNTs align in high magnetic fields due to anisotropic magnetic properties.

Alignment depends on solvent viscosity, temperature, nanotube length, bundling, and field parameters.

Theoretical model based on Smoluchowski equation accurately fits experimental data.

Abstract

We have measured the dynamic alignment properties of single-walled carbon nanotube (SWNT) suspensions in pulsed high magnetic fields through linear dichroism spectroscopy. Millisecond-duration pulsed high magnetic fields up to 56 T as well as microsecond-duration pulsed ultrahigh magnetic fields up to 166 T were used. Due to their anisotropic magnetic properties, SWNTs align in an applied magnetic field, and because of their anisotropic optical properties, aligned SWNTs show linear dichroism. The characteristics of their overall alignment depend on several factors, including the viscosity and temperature of the suspending solvent, the degree of anisotropy of nanotube magnetic susceptibilities, the nanotube length distribution, the degree of nanotube bundling, and the strength and duration of the applied magnetic field. In order to explain our data, we have developed a theoretical model based on the Smoluchowski equation for rigid rods that accurately reproduces the salient features of the experimental data.