Accession Number : AD0770595

Title :   Relaxation Study of the Electric Field Induced Hydrodynamic Turbulence in Nematic Liquid Crystals by Raman Scattering.

Descriptive Note : Technical rept. no. 4, 1 Apr 73-31 Mar 74,


Personal Author(s) : Pan,S. ; Wang,C. H.

Report Date : 21 NOV 1973

Pagination or Media Count : 18

Abstract : Using Raman scattering, the authors have measured the relaxation time of the electric field induced hydrodynamic turbulence in the bulk of several nematic liquid crystal samples as a function of temperature. The induced hydrodynamic turbulence is absent in the solid as well as in the isotropic liquid phase, and thus is a specific property of the anisotropic character of the bulk nematic material. The temperature dependent behavior of the liquid crystals with positive dielectric anisotropy (azo compounds) is found to be rather different from that with negative dielectric anisotropy (azoxy compounds). In both the azo and the azoxy compounds the relaxation time can all be fit to the Arrhenius type of activation process. It is suggested that the dipole-dipole interaction in the compounds of negative dielectric anisotropy is likely to play a very significant role in determining the relaxation behavior of the electrohydrodynamic instability in the bulk of nematic liquid crystal samples. (Modified author abstract)

Descriptors :   *Liquid crystals, Raman spectra, Light scattering, Turbulence, Electric fields, Dipole moments, Relaxation

Subject Categories : Atomic and Molecular Physics and Spectroscopy

Distribution Statement : APPROVED FOR PUBLIC RELEASE