Raman Scattering Study of Phase Biaxiality in a Thermotropic Bent-Core Nematic Liquid Crystal

School of Polymer, Textile and Fiber Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Physical Review Letters (Impact Factor: 7.51). 07/2010; 105(2):027801. DOI: 10.1103/PhysRevLett.105.027801
Source: PubMed


Polarized Raman spectroscopy was used to investigate the development of orientational order and the degree of phase biaxiality in a bent-core mesogenic system. The values of the uniaxial order parameters and , and biaxial order parameters , , and , and their evolution with temperature were determined. The temperature dependence of almost all order parameters reveals a second order transition from the uniaxial to biaxial nematic phase with increasing to ∼0.22 before a first order transition to the smectic-C phase, upon cooling.

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    • "More recent NMR studies resulted in a conclusion that it is necessary to test the material for possible conformational changes [45] and that a transition within the nematic range of A131, identified as one from the uniaxial to the biaxial phase, can be associated with a slowing down of the molecular rotations around the long molecular axis.[46] Two other similar azo compounds have also been claimed to feature the N b phase on the basis of XRD [40] [47] and conoscopy [43] studies. However, explorations of electro-and magneto-optics, surface *Corresponding author. "
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