AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Characterization of Primary and Secondary Organic Aerosol using a Novel Extractive Electrospray Ionization Time-of-Flight Mass Spectrometer (EESI-TOF) from Chamber Studies
Bin Yuan, Giulia Stefenelli, Imad El Haddad, Veronika Pospisilova, Felipe Lopez-Hilfiker, Liwei Wang, Mao Xiao, Yandong Tong, Lu Qi, Sepideh Esmaeilirad, Simone Pieber, Josef Dommen, Urs Baltensperger, Andre S.H. Prévôt, JAY G. SLOWIK, Paul Scherrer Institute
Abstract Number: 475 Working Group: Aerosol Chemistry
Abstract Organic aerosol (OA) is a large component in atmospheric particulate material, affecting urban visibility, human health, and global climate. Secondary organic aerosol (SOA) formation and aging in the atmosphere are still not fully understood. Current online OA measurement techniques are subject to ionization-induced fragmentation and/or thermal decomposition, decreasing the molecular information obtained and thereby compromising source identification and mechanistic studies. A novel extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF) was recently developed at PSI. The fast-response EESI-TOF was shown to measure organic aerosol without fragmentation or thermal decomposition, including oligomeric and thermally unstable species.
In this study, we deploy the EESI-TOF along with other state-of-the-art gas-phase and aerosol measurement techniques (AMS, PTR-TOF, and TOF-CIMS) in a smog chamber to study primary emissions and secondary formation from several important emission sources (e.g wood combustion, coal burning, vehicular emissions, and etc) and representative SOA precursors (e.g. aromatics) in the atmosphere. Emissions (or SOA precursors) are aged using OH or NO3 radicals to simulate daytime and nighttime oxidation processes. These chamber studies provide valuable reference mass spectra for source apportionment of ambient EESI-TOF spectra. Further, the chemical information provided by the EESI-TOF enables investigation of important organic aerosol transformations, including oligomerization, gas-particle partitioning and aging.