THE KERR EFFECT IN AQUEOUS DISPERSIONS OF ANISOTROPIC AND ELECTRICALLY CHARGED LATEX-PARTICLES

Static and dynamic electric birefringence measurements are performed on dispersions of electrically charged fluorinated latex spheres. It is shown that the Kerr constant is made up of three contributions: the first depends on the intrinsic and form anisotropy of the particle; the second arises from the presence of a slowly fluctuating electric dipole which should be originated by the statistics of the surface charge distribution, and the third is connected with the cloud of dissociated counter-ions. This latter contribution shows a non-Lorentzian frequency dispersion, and its amplitude is strongly dependent on the particle concentration and on the ionic strength.