Title

In-Situ X-Ray Measurements of Light-Controlled Layer Spacing in a Smectic-A Liquid Crystal

Publication Title

Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals

Publication Date

1997

Document Type

Article

DOI

10.1080/10587259708046997

Disciplines

Physics

Abstract

The smectic-A phase of octylcyanobiphenyl (8CB) doped with a photosensitive azo-compound has been reported to exhibit structural changes and formation of periodic layers distortions upon exposure to low-level radiation. It is caused by changes in the smectic layer spacing triggered by light-induced molecular photoisomerization of the dopant azocompound. Our in-situ high-resolution x-ray scattering study reveals that the light irradiation controls the smectic spacing. The exposure to UV light increases the layer spacing by as much as 0.5% ( 0.155Å for the studied mixture of 8CB and diheptylazobenzene 7AB at T = 24.00° C). Irradiation by He·Ne laser at 633 nm causes the contraction of the layers.

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