Water activity and surface tension of aqueous ammonium sulfate and D-glucose aerosol nanoparticles

Water activity (a.sub.w) and interfacial energy or surface tension (Ï) are key thermodynamic parameters to describe the hygroscopic growth of atmospheric aerosol particles and their ability to serve as cloud condensation nuclei (CCN), thus influencing the hydrological cycle and climate. Due to size effects and complex mixing states, however, these parameters are not well constrained for nanoparticles composed of organic and inorganic compounds in aqueous solution.