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.
Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals
Krentsel Lobko, Tatiana A.; Lavrentovich, Oleg; Kumar, Satyendra (1997). In-Situ X-Ray Measurements of Light-Controlled Layer Spacing in a Smectic-A Liquid Crystal. Molecular Crystals and Liquid Crystals Science and Technology. Section A. Molecular Crystals and Liquid Crystals 304(1) 463-469. doi: 10.1080/10587259708046997. Retrieved from https://oaks.kent.edu/article/situ-x-ray-measurements-light-controlled-layer-spacing-smectic-liquid-crystal