University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Monday, June 25th 2007
1:30 pm:
Thesis Defense in Physics 236A
Speaker: Peanut McCoy
Subject: Surface structures and reentrant transitions in tilted smectic phases of chiral liquid crystals

Using a series of binary mixtures, we have determined the dependence of the phase sequence upon doping for two compounds with similar chemical structures but inverted phase sequences in one of the pure compounds. The SmC_FI2 phase is favored over the SmC phase on both sides of the mixing phase diagram. In two of these binary mixtures, we observed a reentrant SmC_FI2-SmC-SmC_FI2 transition. Resonant x-ray diffraction identifies the SmC_FI2 phase below SmC and null transmission ellipsometry shows that the phases on either side of SmC have the same structure. The reentrant transition only occurs in thin films.

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