SIZE DISTRIBUTIONS OBTAINED FROM THE INVERSION OF I(Q) USING INTEGRATED LIGHT-SCATTERING SPECTROSCOPY

Traditionally, particle size distributions have been successfully obtained from dynamic light scattering (DLS) data. However, integrated light scattering (ILS) data in the form of I(Q) vs Q contains more information about the particle, especially in the case of hollow or coated spheres where there are sensitivities to the refractive indices and coat thickness. The ILS technique is significantly faster in terms of both data collection and analysis, and number distributions are the immediate product of the inversion of I(Q) vs Q data. Size distributions for both solid and hollow spheres have been obtained using a discrete inversion technique and nonnegative least squares which incorporate either Rayleigh-Gans-Debye (RGD) or Mie theories. The results are compared with size distributions obtained using DLS. In all cases examined, the ILS method proved to be more robust, requiring shorter data collection times and less stringent dependence on sample quality.