On Sizing Impacted Sulfuric Acid Aerosol Particles

Abstract

The method of sizing sulfuric acid aerosol particles collected by impaction is examined and a new model is proposed. It is found that the volume of a particle with the typical morphology of a central particle surrounded by numerous “droplets” can be determined by adding to the volume of the central particle the volume of an acid disc with a diameter equal to the droplet ring diameter and thickness proportional to this diameter. Effects of dehydration of the collected particle in the vacuum evaporation shadowing process and the uptake of ammonia from the laboratory air are found to be important in the determination of the original particle size.