MULTIPLE RELAXATION PHENOMENA IN THE LOW-FREQUENCY DIELECTRIC SPECTRUM OF SMECTIC POLYMORPHS

Dielectric investigations are carried out in the thermotropic liquid crystal, N(rho-n-decyloxybenzylidene)rho-n-octylaniline in the radio frequency range (10 kHz-6 MHz) with the electric field parallel to the director. For the first time, the Cole-Davidson resolved spectrum exhibits a non-Debye type of multiple relaxation phenomena in Smectic-A (SA), smectic-C (SC) and smectic-F (SF) polymorphs. The observed multiple relaxation phenomena reveals the underlying molecular mechanism tuned by the distinct orientational longitudinal dipole motions associated with flexible end chains and central rigid core of the liquid crystal molecule. The estimated activation energies in SA and SC phases are discussed in the light of the available data.