Some experimental investigations on type II chiral liquid crystals

Abstract

We report the following new experimental results on binary mixtures which exhibit the TGB A and UTGB C^∗ phases: (i) optical reflectivity measurements in the cholesteric phase to confirm that the chiral strength decreases as the concentration of the nonchiral compound is increased (ii) electroclinic measurements in the SmA phase to demonstrate that the tilt elastic constant decreases rapidly with concentration, thus enhancing the type II character of the mixture (iii) an irreversible transition from TGB A phase to SmA phase under the action of a low frequency electric field and (iv) occurrence of a new type of periodic radial structure in the meniscus region of free standing films. It is suggested that this structure arises from the type II character of the material.