The Refractive Indices of Isolated and of Aggregated Soot Particles

Abstract

The optical properties of aerosols of finely divided carbon particles depend on the refractive index of a carbon particle, rather than on that of a macroscopic sample of soot which has a substantial volume fraction of voids. It is shown that, provided the voids are sufficiently small and are evenly distributed, a simple relationship exists between the volume polarizabilities of a carbon particle and of soot. The difficulties in determining the refractive index of carbon from the ellipsometricatly determined values for soot samples are discussed and a new method is proposed which avoids these difficulties.