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Liquid Crystals and their Application
Russian Journal

Zhidkie kristally i ikh prakticheskoe ispol'zovanie

Жидкие кристаллы и их практическое использование

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Rus Eng


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Zhidk. krist. ikh prakt. ispol'z. = Liq. Cryst. and their Appl., 2008, 3, 39—44.

Photoinduced Phase Transition Smectic A – Cholesteric in Liquid Crystal Matrices Containing Provitamin D

L. N. Zavora1, N. A. Kasyan1, L. N. Lisetski1, V. D. Panikarskaya1, I. P. Terenetskaya2, T. N. Orlova2, S. I. Torgova3

Author affiliations
1SSI “Institute for Single Crystals”. NAS of Ukraine. 60 Lenin Ave, Kharkov, 61001, Ukraine. 2Institute of Physics. Nauky av. 46, Kyiv 680028, Ukraine 3Institute of Physics RAS, 123995, GSP-5, Moscow D-242, B. Gruzinskaya st., 10-1, Russia

UV-irradiation of liquid crystal mixtures based on cholesterol esters, which contain provitamin D as a non-mesogenic component and form, alongside with the cholesteric phase, smectic A-phase at lower temperatures, can lead to a photoinduced smectic A – cholesteric transition, with a corresponding appearance of visible color upon absorption of a certain dose of UV radiation. The presence of a biological component (provitamin D) makes this system a promising material for bioequivalent UV-dosimetry. Physico-chemical principles governing the process are discussed, which determine the effects of the mixture composition on the sensitivity of the sensor material.

Keywords: UV radiation detectors, bioequivalent UV dosimetry, vitamin D, cholesteric liquid crystals, selective reflection, sensor materials

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