Guinier analysis for homogeneous dielectric spheres of arbitrary size

We shaw that Guinier analysis of the scattered light intensity from a spher e of radius R and refractive index m yields a radius of gyration that is in general larger than the true, geometric value. Moreover, the ratio of thes e two quantities is a roughly universal function of the phase shift paramet er rho = 2kR/m-1/ where k= 2 pi/lambda with lambda being the optical wavele ngth These universal curves are oscillatory and very similar to, but 180 de grees out of phase with, the behavior of the total scattering efficiency. R easons for these behaviors are proposed and their significance for optical particle sizing are discussed. (C) 2000 Elsevier Science B.V. All rights re served.