Abstract View
The Effect of Viscosity on Rate of Fresh SOA Seed Particles Grown by α-Pinene Ozonolysis
DEVON HAUGH, Michael S. Taylor, Murray Johnston, University of Delaware
Abstract Number: 344
Working Group: Aerosol Chemistry
Abstract
Atmospheric nanoparticle formation and growth is a significant source of cloud condensation nuclei. To accurately predict future climate, it is important to understand particle growth mechanisms under varying ambient conditions. Nanoparticle growth is dominated by the condensation of condensable organic vapor (COV), as produced in biogenic secondary organic aerosol (SOA). However, it has been recently established by our group that particle phase reactions play a key role in the growth of aqueous ammonium sulfate droplets in the 40-100 nm size range. These reactions cause droplets to grow from α-pinene ozonolysis products at a rate about 50% faster than inert, solid particles under identical conditions. The work presented here investigates this enhanced growth rate by incorporating freshly generated α-pinene SOA as the seed substrate. Fresh SOA can be glassy- or liquid-like, depending on the relative humidity, which allows for a more inclusive range of viscosity to be studied than inorganic salts. Additionally, fresh SOA seeds are peroxide-rich, and therefore, highly reactive. The work to be presented features a dual flow tube reactor setup and investigates the role of seed viscosity on particle growth rate. Results from these experiments compare effloresced fresh SOA seeds under varying relative humidity conditions as well as deliquesced seeds. Growth rates and mechanisms will be discussed in the context of diameter growth rates of the seed particles.