Mulitphase Chemistry Promotes Isoprene SOA Formation: Recent Results from Field and Lab Studies

Isoprene is a major source of secondary organic aerosol (SOA). Improving our fundamental understanding of isoprene-derived SOA is key to improving existing air quality models, especially since these models currently underestimate observations. By combining organic synthesis, mass spectrometry, smog chamber studies, flow tube studies and field measurements, we show that reactive epoxides, which includes isomeric isoprene epoxydiols (IEPOX), produced from the atmospheric oxidation of isoprene are key to SOA formation. Furthermore, anthropogenic pollutants enhance these epoxides as an SOA source. This presentation will show new laboratory results investigating the effects of pre-existing SOA coatings on reactive uptake and multiphase chemistry of IEPOX. In addition, box modeling studies using existing chamber and flowtube data were conducted in order to constrain the rate constants for SOA components that are not currently included into air quality models. Finally, field measurements are presented in order to provide context for our laboratory and modeling data.