Molecular Diffusion in the Nematic and Smectic C Phase of 4–4′-Di-n-Heptyloxyazoxybenzene (HOAB)

  • J. A. Murphy
  • J. W. Doane
  • D. L. Fishel


Earlier measurements of the diffusion constant of the impurity molecule tetramethylsilane (TMS) when dissolved in a smectic A and smectic B liquid crystal have shown this quantity to be strongly anisotropic.1 That is, the diffusion constant in a direction perpendicular to the long molecular axis, D, (diffusion within the smectic layers) is a much larger quantity than that in a direction parallel to the long molecular axis, D||, with a typical value for the ratio D||/D ~ 0.1. In the earlier work it was not possible, however, to obtain a measure of this ratio in the nematic phase. In this paper we report such a measurement as well as a measurement of the anisotropy in the smectic C phase. Much to our surprise, the ratio D||/D in the nematic phase varies strongly with temperature, exhibiting strong pretransition effects over most of the nematic temperature range.


Anisotropy Coherence Tetramethylsilane MBBA AZOXYBENZENE 


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Copyright information

© Plenum Press, New York 1974

Authors and Affiliations

  • J. A. Murphy
    • 1
  • J. W. Doane
    • 1
  • D. L. Fishel
    • 1
  1. 1.Kent State UniversityKentUSA

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