Experimental characterization of chain-aggregate aerosol by electrooptic scattering

A technique combining the electric field-induced alignment and the transient light scattering was applied to characterize Fe₂O₃ chain-aggregate aerosols. Particles were exposed to a pulsed square electric field with strengths up to 2.S kV/cm. Rotational diffusion constants of the particles were obtained from the decay rate of the relative change in light scattering intensity due to orientation of particles after the removal of electric field. Using a model for rodlike aerosols, average particle length was obtained from the electrooptic scattering data and was compared with the electron microscope analysis of the aggregates sampled with an aerosol centrifuge. The good agreement of the results obtained from the two independent methods demonstrates the applicability of the technique to the in-situ measurement of the fibrous aerosols.