Photoinduced molecular reorientation of absorbing liquid crystals
- 1 August 1997
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review E
- Vol. 56 (2), 1765-1772
- https://doi.org/10.1103/physreve.56.1765
Abstract
The phenomenon of photoinduced molecular reorientation of absorbing nematic liquid crystals is analyzed in a macroscopic general framework and with a specific molecular model. The photoinduced torque responsible for the reorientation is shown to describe a transfer of angular momentum from the molecule center-of-mass degrees of freedom to the rotational ones, mediated by molecular friction. As a consequence, a photoinduced stress tensor is predicted to develop together with the torque in the illuminated fluid. A molecular expression of the photoinduced torque is derived with a rigorous procedure, valid both for a pure material and for a dye–liquid-crystal mixture. This torque expression corrects those reported in previous works on the same subject. The photoinduced torque is evaluated analytically in a simple approximate limit.Keywords
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