AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Quantifying the Thickness of Volatile Particle Coatings
OGOCHUKWU ENEKWIZU, Ali Hasani, Mary McGuinness, Alexei Khalizov, New Jersey Institute of Technology
Abstract Number: 359 Working Group: Carbonaceous Aerosol
Abstract The changes in morphology and mixing state of soot aggregates strongly influence their optical properties. Our previous research has shown that preferential condensation of vapors in the junctions between monomer spheres that compose soot aggregates drives the restructuring of those aggregates. However, establishing a relationship between the degree of restructuring and amount of condensate proved to be a challenge in the case of intermediate volatility vapors due to partial condensate evaporation during aerosol transit from the coating chamber to the detection point. To address this challenge, we built a custom electrostatic precipitator that could be placed at any position after the exit from the coating chamber. The precipitator was calibrated against spherical particles of known sizes and then used to determine the growth profiles of the soot aggregates that were exposed to different amounts of condensable vapor. The amount of condensate lost as a function of transit time was measured as well by varying the distance from the coating chamber to the precipitator. Additionally, for experimental measurements performed using spherical particles, a comparison against the results of a simple aerosol condensation/evaporation model was performed. The results of this study confirm the validity of our previous conclusions regarding the role of capillary condensation in the restructuring of soot aggregates. The implications of our findings on the representation of soot morphology and mixing state in global climate models will be discussed.