10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Spreading Ratios for Aqueous to Glassy Aerosol Particles Using Atomic Force Microscopy (AFM)
ZIYING LEI, Nicole Olson, Rebecca Craig, Andrew Ault, University of Michigan
Abstract Number: 530 Working Group: Aerosol Physics
Abstract The viscosity of atmospheric aerosol particles is a fundamental property that impacts heterogeneous chemistry, phase transitions, and hygroscopicity. Viscosity can be related to the spreading ratio of impacted particles through viscoelastic properties. Particle size, chemical composition, and relative humidity (RH) all affect viscosity, and need to be accounted for when determining and predicting aerosol particle spreading ratios after impaction. However, the viscosity of atmospheric particles is currently poorly quantified, and understanding of spreading ratios from aqueous to glassy aerosol particles is still incomplete. This study aims to determine the relationship between spreading ratio and viscosity of standard aerosol particles composed of inorganic and organic standards. To determine spreading ratio as a function of particle size and RH, laboratory experiments were conducted on size-selected particles (50 – 1,000 nm) under a range of RH conditions (10 – 90%). Atomic force microscopy (AFM) was used to characterize the morphology, height, and projected area diameter of particles, from which the spreading ratio was calculated for individual particles. Changes in spreading ratios were observed with increasing aerosol particle size, as well as with decreasing RH. A fundamental understanding of spreading ratios is will provide insight into the viscosity of aqueous to glassy aerosol particles, which has important implications for water uptake and heterogeneous reactivity.