- Day 2, May 16（Thu.） 10:30-10:50 Room D (202)
Molecular Characterisation of Dimeric Compounds in α-Pinene Secondary Organic Aerosol Using N2 and CO2 Drift Gas Ion Mobility Tandem Mass Spectrometry
Secondary Organic Aerosol (SOA) plays an important role in atmospheric chemistry, impacting Earth’s radiation budget, air quality and human health. Monoterpene SOA contains a large number of multifunctional oxygenated organic compounds such as carboxylic acids, oxo-carboxylic acids, alcohols, hydroperoxides, and accretion reaction products that are made of two or more monomers of oxidation products. Dimer esters are known to be a prominent accretion reaction products in laboratory generated α-pinene ozonolysis SOA, and they can be an important fraction of ambient PM1, especially in boreal forest. To date, almost all the structural elucidation studies of the dimer esters are based on the information obtained from tandem mass spectrometry experiments. While they provide useful information about the chemical formulae of monomer units, the conclusive structural information of monomers remains scarce because these monomers have often isobaric isomer compounds that show very similar fragmentation chemistry. In this study, we subjected two most abundant dimer esters (MW 358 and MW 368) to IMS-HRMSn with N2 and CO2 as drift gases, and evaluated the ability of CO2-IMS to resolve small product ions in IMS-HRMSn. In addition, measured CCS values were compared to theoretically calculated CCS values using modified versions of Mobcal.