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Abstract
Measurements of the complex dielectric permittivity have been performed in the frequency range of the collective director modes (101–106 Hz) in the vicinity of the S*C↔S*A phase transition of the compound 4-[(R)(-)-(2-chloro-3-methylbutanoyloxy)]-phenyl-[4n-decyloxy]benzoate and revealed that a dielectric relaxation process due to collective director fluctuations is active in the helically unwound S*C as well in the S*A phase, if the formation of the S*c helix is suppressed. A twisted and bent director configuration (splayed state) occurs in thin, planar oriented samples with various cell gaps (2–27 μm). The observed mode of Debye type was characterized as a function of temperature and cell thickness. By a decrease of the cell thickness the dielectric increment is lowered in the S*C phase but enhanced in the S*A phase. This Debye mode is only in part suppressed by the application of a bias electric field. With decreasing cell thickness its relaxation frequency decreases in the S*A phase, but increases in the S*C phase.
