Guinier analysis for homogeneous dielectric spheres of arbitrary size

We shaw that Guinier analysis of the scattered light intensity from a sphere 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 these two quantities is a roughly universal function of the phase shift parameter rho = 2kR/m-1/ where k= 2 pi/lambda with lambda being the optical wavelength These universal curves are oscillatory and very similar to, but 180 degrees out of phase with, the behavior of the total scattering efficiency. Reasons for these behaviors are proposed and their significance for optical particle sizing are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.