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

Traditionally, particle size distributions have been successfully obta ined from dynamic light scattering (DLS) data. However, integrated lig ht scattering (ILS) data in the form of I(Q) vs Q contains more inform ation about the particle, especially in the case of hollow or coated s pheres where there are sensitivities to the refractive indices and coa t thickness. The ILS technique is significantly faster in terms of bot h data collection and analysis, and number distributions are the immed iate product of the inversion of I(Q) vs Q data. Size distributions fo r both solid and hollow spheres have been obtained using a discrete in version technique and nonnegative least squares which incorporate eith er Rayleigh-Gans-Debye (RGD) or Mie theories. The results are compared with size distributions obtained using DLS. In all cases examined, th e ILS method proved to be more robust, requiring shorter data collecti on times and less stringent dependence on sample quality.