(729a) Secondary Organic Aerosol From the Mixtures of Isoprene with Sesquiterpenes

Secondary organic aerosol (SOA) is formed in an environmental reaction chamber from the ozonolysis of isoprene and β-caryophyllene (β-C). Experiments are conducted at varying conditions to characterize the effects of hydroxyl radicals, light,for SOA formation. Cloud Condensation Nuclei (CCN) characteristics are also measured. Changes in  SOA chemicophysical properties (e.g. density, volatility, oxidation state) are explored with off and online techniques to improve our predictive understanding of biogenic SOA CCN mixtures. The mixture of β-C and isoprene consumes more ozone than isoprene alone and forms additional SOA with higher CCN activity, O/C, and density. The contribution of β-C, though small in the gas phase, contributes signficantly to the CCN water-uptake properties signficantly. The addition of lower molecular weight terpenes, also improves the CCN predictive capabilities with bulk aerosol chemical information. Results show that aerosol formed from both low and high molecular weight terpene ozonolysis can be significantly hygroscopic and may contribute to the global biogenic SOA CCN budget.