A new optical technique for quantitative studies of switching processes in ferroelectric liquid crystals is reported. The molecular reorientational changes are determined directly as a function of the exciting electric field. By that means, information can be obtained which is similar and complementary to that derived from the polarization current measurements. The method is specially adapted for very low‐frequency regimes (≤0.1 Hz). In contrast to the polarization technique, there are no spurious conductive and capacitive contributions. The features of the method are illustrated by studying the switching process of a 9‐mgr;m‐thick sample ofp‐(n‐decyloxybenzylidene)‐p‐amino‐(2‐methyl‐buthyl) cinnamate (DOBAMBC) under a triangular wave of 0.03 Hz. The temperature dependence of the coercive fields of these low‐frequency cycles is found to obey a power law at the chiral smectic C (Sm C*) phase. The frequency dependence of the coercive fields exhibits a null value at the zero‐frequency limit in contrast to that of the solid‐state ferroelectrics.
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