Sizing of Polymer-Coated Spherical Air Bubbles

Abstract

In this paper we present a fast analytical approach based on Lorenz–Mie theory, which allows us to determine the unknown shell and core radii of two-layered microparticles with refractive indices of 1.0 (air) of the core and 1.5 of the shell, e.g., polymer-coated air bubbles. For this to be achieved, a single particle has to be illuminated (sequentially) both with monochromatic laser light and with a white light source, and the scattered light intensity has to be recorded as a function of the scattering angle in the range from 0° to 170°. Using the autocorrelation and the Fourier transformation of these phase functions, one can deduce the unknown inner and outer radii by comparison with theoretically calculated gauge curves.