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The intrinsic photorefractive effect in the smectic C* phase of a chiral azobenzene

Saipa, Alexander and Osipov, Mikhail and Lanham, Kenneth W. and Chang, Catherine H. and Walba, David M. and Giesselmann, Frank (2006) The intrinsic photorefractive effect in the smectic C* phase of a chiral azobenzene. Journal of Materials Chemistry, 16. pp. 4170-4177.

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Abstract

The ferroelectric properties in the liquid-crystalline smectic C* phase of the chiral mesogenic azobenzene (S)-4-(4-decyloxy-phenylazo)benzoic acid 4-(1-methylhexyloxy)-3-nitro-phenyl ester (‘W470’) were studied and found to be strongly dependent on the intensity of incident light. The light-induced trans to cis isomerization of the azobenzene chromophore which is an intrinsic constituent of this SmC* mesogen leads to a pronounced photoferroelectric effect since the ferroelectric SmC* ordering is considerably disturbed by the presence of bent-shaped cis-isomer molecules: At increasing light intensity a strong decrease of both SmC* order parameters, spontaneous electric polarization Ps and director tilt angle θ, is observed. It is further seen that even the nature of the ferroelectric transition is affected by the photoisomerization which leads to a crossover from the nearly tricritrical transition observed in the absence of light to a typical second-order transition. This result is interpreted theoretically taking into account a coupling between the director tilt and the biaxial order parameter which is strongly affected by the light-induced generation of the bent-shaped cis-isomers. The dynamics of the intrinsic photoferroelectric effect in W470 was studied by time-resolved measurements of spontaneous polarisation and director tilt.

Item type: Article
ID code: 30092
Keywords: chiral mesogenic azobenzene , liquid-crystalline smectic C, Physical and theoretical chemistry, Probabilities. Mathematical statistics, Materials Chemistry, Chemistry(all)
Subjects: Science > Chemistry > Physical and theoretical chemistry
Science > Mathematics > Probabilities. Mathematical statistics
Department: Faculty of Science > Mathematics and Statistics
Related URLs:
    Depositing user: Pure Administrator
    Date Deposited: 10 May 2011 15:15
    Last modified: 05 Sep 2014 08:06
    URI: http://strathprints.strath.ac.uk/id/eprint/30092

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