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APS » Journals » Phys. Rev. Lett. » Volume 92 » Issue 14
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Phys. Rev. Lett. 92, 145505 (2004) [4 pages]

Thermotropic Biaxial Nematic Liquid Crystals

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L. A. Madsen, T. J. Dingemans*, M. Nakata†, and E. T. Samulski
Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA

Received 14 July 2003; published 9 April 2004

See accompanying Physics Focus

We have synthesized liquid crystal (LC) mesogens based on a nonlinear oxadiazole unit that exhibit nematic phases near 200 °C. Polarized microscopy and conoscopy indicate that these LCs are biaxial nematics. Unambiguous and quantitative evidence for biaxiality is achieved using 2H NMR spectroscopy. “2D powder” spectra, obtained by rotating 2H-labeled samples about an axis perpendicular to the magnetic field at ∼200  Hz, yield phase biaxiality parameters of ∼0.1 when coupled with rigorous and proven simulations.

© 2004 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.92.145505
DOI:
10.1103/PhysRevLett.92.145505
PACS:
61.30.Gd, 61.30.Eb

*Permanent address: Fundamentals of Advanced Materials Group, University of Delft, 2629 HS Delft, The Netherlands.

†Permanent address: Department of Organic and Polymeric Materials, Tokyo Institute of Technology, Tokyo 152-8552, Japan.

 
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