Date of Award

Spring 1999

Document Type

Restricted Thesis

Terms of Use

© 1999 Benjamin P. Huff. 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

The optical activity of [S,S]-EPHDBPE, a helix inversion compound, is characterized in the chiral nematic phase. The natural chirality of [S,S]-EPHDBPE with small amounts of Cholesteryl Myristate added is characterized in the chiral nematic phase, and the optical activity of the same mixtures due to pretransitional fluctuations of order is measured in the isotropic phase. No helix inversion is observed in the isotropic phase. Our findings suggest that current theories relying on molecular reasoning to explain helix inversion are inadequate because these theories would predict a helix inversion in the isotropic phase. A modified Maier-Saupe theory is considered as an alternate theory to explain helix inversion that also takes into account intermolecular forces. Preliminary data from the Cholesteryl Myristate / [S,S]-EPHDBPE experiments agree qualitatively with the Maier-Saupe theory. Direct measurements of the chirality of different concentrations of CE6 were attempted in both the chiral nematic and isotropic phases. While qualitatively the CE6 results support the modified Maier-Saupe theory somewhat, the data is inconclusive and more experiments or a different approach is needed.

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