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

• Published in: ACS nano Vol. 3; no. 1; pp. 131 - 138
• Main Authors: Shaver, Jonah, Parra-Vasquez, A. Nicholas G, Hansel, Stefan, Portugall, Oliver, Mielke, Charles H, von Ortenberg, Michael, Hauge, Robert H, Pasquali, Matteo, Kono, Junichiro
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 27.01.2009
• Subjects: Algorithms; Anisotropy; Carbon - chemistry; Condensed Matter; Electromagnetic Fields; Light; Microscopy, Atomic Force; Models, Statistical; Nanoparticles - chemistry; Nanotechnology - methods; Nanotubes - chemistry; Nanotubes, Carbon - chemistry; Physics; Rheology; Spectrum Analysis; Superconductivity; Surface Properties; Time Factors; light absorption and transmission; optical properties of carbon nanotubes; carbon nanotubes; absorption spectra of molecules; dichroism of molecules; generation of high magnetic fields
• ISSN: 1936-0851; 1936-086X
• DOI: 10.1021/nn800519n

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. Because of 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. 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.