AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Pressure Dependence of Criegee Intermediate Stabilization for a Sequence of Alkenes
JANI HAKALA, Neil Donahue, Carnegie Mellon University
Abstract Number: 460 Working Group: Aerosol Chemistry
Abstract Alkenes are the most abundant organic species in the atmosphere after methane. These include such species as isoprene and vast selection of different terpenes. Alkene ozonolysis is a major pathway for removal of alkenes from the atmosphere and an important step for the formation of Secondary Organic Aerosols. Stabilized Criegee Intermediates (sCI) are a species of atmospheric oxidizer, which are formed by alkene ozonolysis via Criegee mechanism. Particularly their ability to oxidize sulfur dioxide into sulfuric acid is important for predicting the rate of new particle formation in the atmosphere.
The role of sCIs in atmospheric chemistry is not yet fully understood. To deepen our knowledge, we have studied the pressure dependence of criegee intermediate stabilization of several symmetrical trans-alkenes and monoterpenes. We measured the criegee intermediate stabilization in a pressure controlled flow reactor indirectly by measuring the sulfuric acid formed by sulfur dioxide oxidation by sCIs using a Chemical Ionization Mass Spectrometer (CIMS). The results indicate collisional stabilization of criegee intermediates, and for some alkenes, also some stabilization without a need for a third body.