Liquid Crystal Properties of Aggregated Dyes Viva Horowitz

Purpose Investigating a liquid crystal phase of an aggregated dye Very little work has been done so far, according to the literature e.g. measure birefringence as a function of temperature Birefringence ∆n is a measure of the difference in the index of refraction for light polarized along one direction, compared to another direction

Liquid Crystals A liquid crystal is a fluid with orientational order. An isotropic liquid has no orientational order. A nematic liquid crystal’s molecules do not have positional order Order Parameter S = (3/2) cos2 q - 1/2

Sunset Yellow FCF Nematic phase Orange-red powder Used as a food coloring Chemical diagram from http://topcat.iit.bme.hu/~joker/eec/eec/e0110.html Uses: http://www.standardcon.com/sunsetyellowfcf.htm

Absorption Spectrum of Monomer

Procedure for Mapping Phase Diagram Mix solutions Make sealed cell with sample Cell is placed on heating stage on microscope, between crossed polarizers The cell is slowly heated, and temperatures are recorded Goal: Phase Diagram

Current Work Upcoming: Order parameter measurements Birefringence measurements Upcoming: Order parameter measurements