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. An asymmetry 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 of the 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 described 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.