AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
MOVI-CIMS Measurements of Organic Aerosol Generated by a Potential Aerosol Mass (PAM) Reactor
PUNEET CHHABRA, Andrew Lambe, Timothy Onasch, Manjula Canagaratna, John Jayne, Scott Herndon, Douglas Worsnop, Paul Davidovits, Aerodyne Research, Inc.
Abstract Number: 640 Working Group: Aerosol Chemistry
Abstract We present semi-continuous measurements from a micro-orifice volatilization impactor (MOVI) inlet coupled to a chemical ionization mass spectrometer (CIMS). This instrument is capable of generating high resolution time-of-flight mass spectra of gas and particle-phase organic compounds, as well as thermograms of particle-phase organics desorbed from the MOVI inlet. Here, acetate reagent ions were used in the HRToF-CIMS to facilitate the selective measurement of organic acids with minimal fragmentation. The MOVI-CIMS was used to characterize the chemical composition of laboratory secondary organic aerosol (SOA) generated in a Potential Aerosol Mass (PAM) flow reactor. Mass spectra were characterized following exposure of biogenic and anthropogenic SOA precursors to OH radicals over timescales of approximately 1 to 10 days of equivalent atmospheric oxidation at an average OH concentration of 2*10$^6 molec cm$^(-3). Positive matrix factorization of the CIMS mass spectra was used to identify gas- and particle-phase oxidation products that correspond to different generations of oxidation in the PAM reactor. These results should aid in the interpretation of ambient HRToF-CIMS measurements. Lastly, comparisons to parallel HR-ToF-AMS measurements are made to relate the CIMS results to the total secondary organic aerosol composition produced in these experiments.