Specific features of provitamin D3 photoisomerization in a cholesteric liquid crystal

The method of UV absorption spectroscopy is used to study the influence of the cholesteric pitch on the efficiency of previtamin D (photoisomer of provitamin D 3 ) cis-trans isomerization in a cholesteric liquid crystal (nematic + optically active dopant + provitamin D 3 ). It is found that a change...

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Bibliographic Details
Published in:Optics and spectroscopy 2010, Vol.108 (4), p.608-612
Main Authors: Orlova, T. N., Terenetskaya, I. P.
Format: Article
Language:English
Subjects:
Condensed-Matter Spectroscopy
Lasers
Optical Devices
Optics
Photonics
Physics
Physics and Astronomy
Online Access:Get full text
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Summary:The method of UV absorption spectroscopy is used to study the influence of the cholesteric pitch on the efficiency of previtamin D (photoisomer of provitamin D 3 ) cis-trans isomerization in a cholesteric liquid crystal (nematic + optically active dopant + provitamin D 3 ). It is found that a change in pitch from 14 to 0.364 μm due to an increase in the concentration of an optically active dopant in a wide range (1.6–61 wt %) only slightly reduces the efficiency of the cis-trans isomerization. However, small changes in pitch (0.364–0.368 μm) due to an increase in the provitamin D 3 concentration within the range of 0.07–2.2 wt % significantly increase the efficiency. Reducing in the influence of provitamin D 3 concentration on the cis-trans isomerization efficiency with an increase in mesophase temperature was found in both nematic and cholesteric liquid crystals up to the disappearing of the concentration dependence in the isotropic phase. Altogether, the obtained results indicate the collective character of cis-trans isomerization in liquid crystals due to the ordering of the medium.
ISSN:0030-400X
1562-6911
DOI:10.1134/S0030400X10040156