X-Ray Studies of Thermotropic Liquid Crystals

  • R. Shashidhar
Part of the NATO ASI Series book series (NSSB, volume 290)


Thermotropic liquid crystals are characterized by three types of order: orientational order, positional order and bond orientational order1. These can be short range order, quasi long range order or long range order. X-ray diffraction studies serve to probe the types and extent of the order. Such studies not only enable us to understand the structure of the mesophase, but also permits us to investigate how fluctuations associated with shortrange smectic-like order develop close to phase transitions. With the advent and extensive development of the high resolution X-ray scattering techniques, we are now in a position to measure correlation lengths extending to a few micrometers. This resolution, coupled with the ability to achieve a millikelvin temperature control, have led to a variety of new results which are fundamentally important in our understanding of condensed matter. In this chapter, we shall describe in some detail three important results: 1) observation of algebraic decay of positional order in smectic-A; 2) critical divergence of anisotropic correlation lengths near the nematic-smectic- A transition and 3) a new type of critical point involving two smectic A phases of the same symmetry.


Liquid Crystal Nematic Phase Tricritical Point Smectic Phasis Positional Order 
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Copyright information

© Springer Science+Business Media New York 1992

Authors and Affiliations

  • R. Shashidhar
    • 1
    • 2
  1. 1.Naval Research LaboratoryCenter for Bio/Molecular Science & EngineeringUSA
  2. 2.Geo-Centers, Inc.Fort WashingtonUSA

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