AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Sustained Chemical Evolution of alpha-Pinene Ozonolysis Products - Evidence for Bulk Phase Reaction
PETER DECARLO, Torsten Tritscher, Lisa Pfaffenberger, Arnaud Praplan, Peter Barmet, Kaytlin Henry, Josef Dommen, Neil Donahue, Andre Prévôt, Urs Baltensperger, Drexel University
Abstract Number: 643 Working Group: Aerosol Chemistry
Abstract During the MUltiple CHamber Aerosol CHemical Aging Study 2 (MUCHACHAS-2) at the Paul Scherrer Institute, aerosol products generated from the ozonolysis of alpha-pinene (AP) were observed to undergo continual chemical aging, in the absence of light and additional oxidant injection. Particle size and chemical composition were monitored with standard instrumentation including an Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (AMS) and a Volatility Hygroscopic Tandem Differential Mobility analyzer (VHTDMA). Gas phase evolution was monitored with a PTRMS and ozone monitor. AMS results show continued chemical evolution of ozonolysis generated secondary organic aerosol (SOA) without additional OH exposure and after the precursor had been consumed. Showing that the AP ozonolysis system does not reach a equilibrium but continues to react. Increases in signal intensity with time was observed for several high molecular weight (150-250 amu) species. These observations indicate that while glassy aerosol may be important from a volatility reduction perspective, chemical change of the SOA needs to also be considered.