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Proceedings Paper

Direct evidence of the molecular interaction propagation in the phase transition of liquid crystals
Author(s): Kenji Katayama; Takahiro Sato; Shota Kuwahara
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Paper Abstract

The molecular interaction sometimes propagates in a collective manner, reaching for a long distance on the order of millimeters. Such interactions have been well known in the field of strongly-correlated electron systems in a beautiful crystal interleaved by donor and acceptor layers, induced by photo-stimulus. The other examples can be found in liquid crystals (LCs), which could be found in many places in nature such as bio-membrane. Different from crystals, LCs features “softness”, which enables it to be a curved structure such as a cell. In LCs, even a small molecular change would trigger the overall structural change by the propagation of the molecular interaction. Here we will show, for the first time, how long and how fast the molecular interaction propagates in LCs. The patterned phase transition was induced in a LC, causing the phase transition propagation in a controlled way and the propagation was measured with an time-resolved optical technique, called the transient grating. A LC sample doped with azobenzene was put into a thermally controlled LC cell. A grating pattern of a pulse light with 355 nm was impinged to the LC cell, and the light was absorbed by the dyes, releasing heat or photomechanical motion. We could observe the fringe spacing dependence on the phase transition response, which indicates that phase transition was delayed as the fringe spacing due to the delay by the phase transition propagation. This is the first direct evidence of the molecular interaction propagation of the LC molecules.

Paper Details

Date Published: 23 September 2016
PDF: 4 pages
Proc. SPIE 9940, Liquid Crystals XX, 99400W (23 September 2016); doi: 10.1117/12.2235852
Show Author Affiliations
Kenji Katayama, Chuo Univ. (Japan)
Takahiro Sato, Chuo Univ. (Japan)
Shota Kuwahara, Toho Univ. (Japan)

Published in SPIE Proceedings Vol. 9940:
Liquid Crystals XX
Iam Choon Khoo, Editor(s)

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