Dielectric function of a colloidal solution near an interface with pure solvent

The effective dielectric function of colloidal solution in the vicinity of a solution¿pure solvent interface is discussed. A simple expression is derived for the transverse and longitudinal components of the dielectric permittivity tensor epsilon-tensor as a function of the distance from the interface. In the approximation made, the sole effect responsible for the epsilon-tensor anisotropy and space dependence is the asymmetry in the pair correlation function. Consequently, the final result is valid for dilute solutions only. The effect of polydispersity of the solute particles is considered in an approximate manner as well.