Two dimensional angular light scattering in aqueous NaCl single aerosol particles during deliquescence and efflorescence

We present a new method to analyze two dimensional angular light scattering patterns of single aerosol particles by image processing. A pattern distortion parameter can be calculated to determine the solid to liquid partitioning in micron sized composite particles similar to using temporal light scattering intensity fluctuations. We use the scattering patterns during deliquescence of a NaCl crystal to prove the feasibility of the method. In addition we show that even fast processes like the efflorescence from a supersaturated solution droplet can be analyzed where temporal fluctuation analysis fails. We find that efflorescence cannot be escribed as a time reversed deliquescence. There is indication that during efflorescence a solid shell grows at the surface of the liquid droplet which finally collapses due to mechanical stress. (C) 2001 Optical Society of America.