TEMPORAL BEHAVIOR OF THE ELECTROCLINIC EFFECT IN CHIRAL SMECTIC-A

We have measured the temporal behaviour of the electroclinic effect in chiral Sm A by monitoring the optical response to a square voltage pulse as function of the pulse height for various small cell gaps. We corrected for the distortion of the pulse shape as arriving at the liquid crystal layer due to the RC-time of the cell. (Here R is the resistance of the ITO contact leads, and C is the cell capacitance.) The Garoff and Meyer dynamical formula (Phys. Rev. Lett. 38, 848 (1977)) with the aforementioned correction was shown to correctly describe the temporal behaviour of the induced tilt angle. However, the electroclinic response time x depended on the applied electric field E and the cell gaps d. The static, equilibrium value of the induced tilt angle did not depend on d and remained linear in E down to values of 0.1 V/μm, which agrees with results of a continuum theory calculation. We believe that the d and E-dependence of is caused by the aligning interaction of the boundaries, which gains importance over the volume electroclinic interaction for small d and E-values. © 1991 Gordon and Breach Science Publishers S.A.