Light-induced molecular adsorption and reorientation at polyvinylcinnamate-fluorinated/liquid-crystal interface.
We have carried out a detailed experimental study, by means of x-ray reflectometry (XRR) and half-leaky guided mode (HLGM) optical characterization, of the light-induced molecular adsorption and reorientation at the polyvinylcinnamate-fluorinated (PVCN-F)/liquid-crystal (LC) interface of a LC cell doped with the azo-dye methyl red (MR). The XRR data allowed characterizing the microscopic structure of the adsorbed dye layer both before irradiation (dark adsorption) and after irradiation (light-induced adsorption). The HLGM optical characterization has made possible the experimental determination of the nematic director profile in the LC cell and evaluation of the effects of light-induced adsorption on the LC anchoring conditions. The experimental findings have confirmed the formation of a dark-adsorbed layer and are in agreement with the absorption model previously proposed to account for the complex phenomenology related to light-induced anchoring and reorientation in dye-doped liquid crystals.
Francescangeli
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Dipartimento di Fisica e Ingegneria dei Materiali e del Territorio and Istituto Nazionale per la Fisica della Materia, Università Politecnica delle Marche, Via Brecce Bianche, 60131 Ancona, Italy.
Lucchetti
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Simoni
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Stanić
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Mazzulla
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