PSSM Workshop on Liquid Crystals and Colloidal Dispersions
Photochemical switching between colloidal photonic crystals at the nematic-air interface
Stanislav Chernyshuk, Institute of Physics
Abstract: A direct observation of the photochemical switching between colloidal crystals with different lattice constants in a liquid-crystal emulsion is reported. Glycerol droplets introduced in a nematic liquid crystal form two-dimensional hexagonal colloidal crystal at the nematic-air interface with a lattice constant depending on the surface tension LCA. We dope an azobenzene derivative into the LC emulsion to modulate the colloidal structures by using cis-trans photoisomerization of the doped dye. The photoisomerization changes surface tension of LCA and the lattice constant of colloidal crystals with a relaxation time T about 10 s. A simple theoretical description, which qualitatively agrees with experimental results, has been proposed. Possible applications in infrared range photonic crystals are discussed. The number of different kinds of dyes N set the number of different possible photonic crystals as 2^N, which may be transformed one into another by corresponding 2N light beams inducing cis-trans photoisomerization of the doped dyes.
Reference:
B. Lev, S. B. Chernyshuk,T. Yamamoto, J. Yamamoto and H. Yokoyama, Photochemical switching between colloidal photonic crystals at the nematic-air interface, Phys.Rev. E , 78, 020701(R) (2008)
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| June 10, 2009: | Final Program |
| June 22, 2009: | PSSM Workshop |
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