Date of Award

Spring 2003

Document Type

Restricted Thesis

Terms of Use

© 2003 Mark Romanowsky. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Physics & Astronomy Department

First Advisor

Peter J. Collings

Abstract

We have investigated the fluctuations of short-range order in several liquid crystal compounds by measuring the scattering of visible light. We have verified the linear temperature dependence of the leading term in the Landau-de Gennes free-energy expression in the isotropic phase. We have also obtained estimates for the bare correlation length, in the one-constant approximation, in the compounds isothiocyanato-4-(trans-4-propylcyclohexyl) benzene (ICPCHB) and p-pentyl-p'-cyanobiphenyl (5CB). For ICPCHB we find ζ₀ = 2.5 ± 2.2 Å, and for 5CB we find ζ₀ = 3.3 ± 0.7 Å. Using a different approach with 5CB, we find that without the one-constant approximation, ζ₁₀ = 4.7 ± 0.6 Å. We furthermore find our observations consistent with a direct variation between the polarizability of a liquid crystal molecule, and the bare correlation length of its nematic phase.

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