Effect of mixing structure on the water uptake of mixtures of ammonium sulfate and phthalic acid particles

Abstract. Aerosol mixing state regulates the interactions between water molecules and particles thus controls aerosol activation hygroscopic growth, which thereby influences visibility degradation, cloud formation, its radiative forcing. There are, however, few current studies on structure effects hygroscopicity. Here, we investigated hygroscopicity of ammonium sulfate / phthalic acid (AS PA) with different mass fractions PA in states terms initial particle generation. Firstly, effect coatings behavior core-shell-generated mixtures AS was studied using a coating tandem differential mobility analyzer (coating HTDMA). The slow increase growth factor is observed increasing thickness prior to deliquescence relative humidity (DRH) AS. At (RH) above 80 %, decrease occurs as shell increases, indicates that leads reduction overall In addition, use Zdanovskii–Stokes–Robinson (ZSR) relation underestimation measured factors without consideration morphological particles, especially at higher RH. Secondly, case initially well-mixed shift DRH (∼80 Tang Munkelwitz, 1994) lower RH due presence particles. predicted ZSR consistent Moreover, compared discussed influence uptake It found slightly than same %. observation may contribute growing field knowledge regarding properties uptake.