Aerosol studies by light scattering. IV. Preparation and particle size distribution of aerosols consisting of concentric spheres

Abstract

Coated aerosols consisting of silver chloride spheres encased in a concentric shell of linolenic acid have been prepared and their particle size distribution analyzed by light scattering. The procedure involves preparation of a silver chloride aerosol of uniform particle size by condensation of silver chloride vapor upon sodium chloride nuclei in a high temperature generator. The size distribution of the silver chloride aerosol particles is determined by light scattering using the polarization ratio method and is confirmed by electron microscopy. The vapors of linolenic acid are next condensed upon the silver chloride particles forming the coated aerosols. These are then analyzed by the polarization ratio method using the theory of scattering by concentric spheres. In order to simplify the computations a model is assumed for which either the thickness of the coating on each particle is constant or the volume of coated material is constant. For the range of parameters used here, both models give equivalent results. The linolenic acid can be fixed by OsO₄ and the size distribution of the coated aerosols also confirmed by electron microscopy.