Refractive index of particles in the colloidal state

Abstract

Using light scattering theory, expressions for the refractive index increment of colloidal dispersions are derived for collodial particles in the Rayliegh, Rayleigh–Gans and anomalous diffraction light scattering regions. The theory of operation of the Brice-Phoenix differential refractometer is reconsidered for the case of turbid samples in the divided cell. Refractive index increment measurement are reported for two dilute colloidal system: an aqueous kaolinite and an aqueous synthetic polymer latex dispersion, both with a range of paticle sizes. Theory and experimental results are used to obtain the refractive index of the disperse phase for the two systems and the results compared with refractive index data derived in other ways.