OPTICAL EFFECTS IN STRATIFIED COLLOIDAL PARTICLES NEAR TRANSPARENCY

Non-isotropic scattering patterns showing a minimum for small and almo st transparent core-shell particles are discussed. It is shown that fo r any particle size, close to transparency, a core-shell particle beha ves optically differently from a non-structured particle due to the pr esence of a minimum in the scattering pattern. Transparency criteria a re discussed in the light of the non-isotropic character of the scatte red light. Direct experimental evidence of the existence of this minim um is presented and compared with the theoretical predictions of the s cattering by colloids having a distribution of particle composition.