Determination of the Optical Properties of Hollow Glass Sphere Aerosols

Abstract

Abstract : Optical modeling of hollow glass sphere aerosols was undertaken with a two stage approach. The first stage was to develop a model for homogeneous or solid spheres. This was a logical means of proceeding, since modeling of homogeneous spheres is by far the easier of the two tasks and is the area which has received by far the greatest attention from other investigators, hence providing copious examples with which to check our results. The homogeneous glass sphere model, based on the formulation of Mie (1908), was developed without any serious problems and was successfully tested. The second stage of development of optical models consisted of the much more difficult task of developing a model for composite or hollow spheres. The modeled aerosol consists of two concentric spheres composed of two different materials. Results are very different in appearance from those of the solid glass spheres. Qualitatively, this departure can be understood as a combination of two phenomena, a solid sphere of variable refractive index at large aerosol radii and a thin film interference phenomenon at small aerosol radii.