Permittivity of suspensions

The permittivity of a suspension treated as a system of hard spheres is calculated in the Born approximation. The structure of the suspension is described by the Percus-Yevick correlation function. The permittivity of the system under consideration is expressed through a nonlocal susceptibility whose spatial extension is determined by the form factor of suspension particles and the characteristic value of the structure factor. It is shown that the permittivity of the suspension mixture is characterized by a spatial dispersion that manifests itself already in the first order of the perturbation theory. It is demonstrated that the concentration dependences of the extinction length and the transport length calculated from the obtained data on the permittivity tensor exhibit substantially nonlinear behavior. Within the range of applicability of the theory, the results obtained are in agreement with available experimental data.