We have used linear dichroism spectroscopy to measure the dynamic alignment of single-walled carbon nanotubes (SWNT) in pulsed magnetic fields up to 55 T. We make use of the fact that SWNTs absorb light only when the electric-field vector is oriented parallel to the tube axis. SWNTs thus produce a polarization dependent change of the optical transmission, that permits precise measurements of their orientation. In order to distinguish the influence of different mechanisms governing the alignment such as the external magnetic field, Brownian motion or the tube length, we have systematically varied parameters such as the viscosity of the aqueous solution and the sample temperature.
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Acknowledgements Part of this work has been supported by EuroMagNET under the EU contract No 228043. The authors gratefully thank Sylvie George and the LNCMI machine shop for technical support.
- Carbon nanotubes
- Pulsed magnetic fields