Small‐Angle light scattering from an anisotropic sphere: Anisotropy and size effects

Abstract

AbstractThe recently developed theory of light scattering from an anisotropic sphere (taken as a model for a spherulite) summarizes all information obtainable from such scattering system when the Rayleigh‐Gans‐Debye approximation is appropriate. The commonly used procedure of size determination from the maximum of the Hv intensity is tested for a number of models differing in radius size, inherent anisotropy δn and mean refractive index ¯n. It has been confirmed, that the parameter (¯n ‐ 1)/δn plays the decisive role in the angular dependence of the Hv intensity and the influence of that parameter on the size determination and resulting accuracy is specified. The results differ for positive and negative spherulites and the stabilizing role of increasing spherulite size in accuracy of procedure is demonstrated. It has been shown that the RGD approximation is appropriate especially for the case of homogeneous spherulite texture (thus implying, that the refractive index of the surrounding is close to the average refractive index of a single spherulite). The results extrapolated outside of the RGD approximation display invariable Umax position for isotropic contribution with increasing sphere size in contrast to the oscillatory character of Umax predicted by the LM solution. It is proposed to construct the anisotropic solution under an approximation recently suggested for thin anisotropic shell. © 1994 John Wiley & Sons, Inc.