Electro-optical properties of colloids

Abstract

In this paper we describe the nature of electo-optical phenomena observed in colloid systems, and the peculiarities of effects compared to electro-optics of homogenous media are discussed. Among the different types of optical phenomena induced in colloids by electric fields we here emphasize birefringence, dichroism, electric light scattering (alteration of intensity of scattered light caused by particle orientation in electric field) and anisotropy of light scattering (difference of light intensity scattered parallel and orthogonal to the applied external electric field). The brightest electro-optical effects in colloids with particle size comparable to light wave length are anisotropy of light scattering and conservative dichroism. The electro-optical techniques that have been developed so far are also discussed in this paper. Special attention is paid to the techniques based on the study of dichroism caused by electric fields of different types which were developed by the Russian school of electro-optics. The results of the study of such particle characteristics as electric polarizability, specific surface conductivity, permanent dipole moment and particle size are presented. The results of experimental verification of the theory of double electric layer polarizability of the interface are presented. Refs 94. Figs 2. Tables 1.