Size distributions of polydisperse particles were theoretically derived from scattered light having multi-wavelength by the singular value decomposition (SVD). Junge and log-normal distributions were assumed, and angular distributions of scattered light were numerically calculated based on Mie theory within the size range of particle radius from 0.05 to 2.5 micrometer. Dependencies of the inverted solutions on the effective digits intensity, transformation factor, and the number of measured points of scattering angles were discussed. We measured angular distribution of scattered light intensity of laser beam from polydisperse polystyrene latex (PSL) particles suspended in water, and obtained the size distribution by the application of the SVD. A similar study was performed for scattered light intensity of different wavelengths at a given scattering angle.
The conversion of SO2 gas to sulfuric acid particles is a very important problem in the air pollution control. A new approach using a PIXE (Particle Induced X-ray Emission) technique is attempted to determine the conversion rate of SO2 to H2SO4 particles. Sulfuric acid particles were formed photochemically in the SO2/clean air or SO2/atmospheric air systems using a flow type smog chamber. The total number concentration was monitored with a CNC and the particle size distribution was measured with an EAA. Sulfuric acid particles were collected onto the 0.2 μm pore-size Nuclepore filter to determine the conversion rate. The first order conversion rates of SO2 to H2SO4 particles ranged from 0.007 to 0.035 h-1 under the conditions of dry(<2 % r.h.)-80 % r.h., 5-20 ppm SO2 and 75-300 s reaction time.