Infrared and Raman spectroscopy has been widely used at last decade to elucidate the properties of liquid crystals, the structure of the liquid crystal molecules and the molecular motion in various types of mesophase1. Among more than 50 papers dealing with liquid crystals only a few consider the influence of electric field on mesophase vibrational spectrum. First Nelf2has used the electric field to orient nematic samples of p-methoxybenzylidene p′-cyanoaniline for the investigations of IR dichroism. Assuming that a large liquid crystalline domain acts like a rigid dipole and taking into account the effects of the walls an expression for the dichroism ratio was derived to evaluate the degree of orientational order. Later, Ohnishi3has applied a d.c. electric field to a cell filled with MBBA and studied the changes in the relative transmittance of some bands in the region 4000–1000 cm−1of the dynamic scattering mode. Pan and Wang4found that in the presence of turbulence due to the application of electric field, the intensity of all Raman bands decreases drastically but without any shift in the peak positions.