Abstract View
Growth of Fresh SOA Seed Particles by α-Pinene Ozonolysis
DEVON HAUGH, Michael S. Taylor, Michael J. Apsokardu, Murray Johnston, University of Delaware
Abstract Number: 279
Working Group: Aerosol Chemistry
Abstract
Ambient nanoparticle formation and growth is an important source of cloud condensation nuclei. For this reason, understanding growth mechanisms is particularly important for predicting climate. For biogenic secondary organic aerosol (SOA), condensation of highly oxidized organic molecules (HOMs) contributes substantially to nanoparticle growth. However, particle phase reactions can also play a role. Recent work in our group has shown for SOA produced by a-pinene ozonolysis that size-selected aqueous droplets in the 40-100 nm size range grow about 20% faster than inert, solid particles. The work presented here extends these studies to the growth of size-selected seed particles consisting of fresh SOA. Depending on relative humidity, these particles can be glassy- or liquid-like, and in either case they are likely to be peroxide-rich, and therefore, highly reactive. The particle growth experiments to be presented use a dual flow tube reactor assembly, where the first flow tube generates fresh SOA seed particles from a-pinene ozonolysis that subsequently react in the second flow tube. Results from two types of particle growth experiments will be described: 1) growth proceeds by exposing seed particles to additional amounts of a-pinene and ozone, and 2) growth proceeds by exposing seed particles to vapors of specific compounds that are known to be produced by a-pinene ozonolysis. Growth mechanisms will be discussed in the context of measured diameter growth rates of the seed particles and chemical composition of the grown particles.