AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Sorption of Semi-volatile α-Pinene SOA into Non-volatile Polyethylene Glycol Seeds
PENGLIN YE, Neil Donahue, Carnegie Mellon University
Abstract Number: 329 Working Group: Aerosol Chemistry
Abstract Semi-volatile organic compounds (SVOCs) play an essential role in the formation and chemical ageing of secondary organic aerosol (SOA), and also the mixing of organic aerosol (OA) from different sources. Studying the sorption of SVOCs into particles is very important for understanding the potential contribution of SVOCs to the global aerosol budget. The gas-particle partitioning of SVOCs is influenced by the saturation concentration of the SVOC, the total amount of OA and the viscosity of OA. PEG400 may be a very good organic seed with special prosperities, liquid, water-soluble, nearly non-volatile, good solvent for SOA and relatively stable during oxidation with OH radicals and ozone. The mass spectrum of PEG400 can be easily separated from the SOA mass spectrum with a unique fragment C4H9O2+ at m/z = 89. We injected PEG400 particles into a smog chamber after SOA formation from a-pinene onto ammonium sulfate seeds had reached completion, with no sign of ongoing condensation. We then measured mass spectra of individual particles using a high resolution Aerosol Mass Spectrometer including light scattering single particle detection. Significant sorption of semi-volatile α-pinene SOA into the PEG400 particles was evident based on a significant SOA mass increase, a shift of the particle size distribution and also single-particle composition. The results also demonstrated that SOA prepared from α-pinene oxidized with OH radicals produced more semi-volatile SOA vapors than α-pinene oxidized by ozone. More semi-volatile SOA vapors were observed in the gas phase with higher SOA loadings. This method allows further investigation of properties such as volatility and composition of semi-volatile SOA vapors using well established measurement methods for particles.