AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Reactions of Condensed Phase Alkoxy Radicals
ANTHONY CARRASQUILLO, Kelly Daumit, Jesse Kroll, MIT
Abstract Number: 201 Working Group: Aerosol Chemistry
Abstract Our understanding of the major processes that influence the chemical evolution of organic aerosol derive from experimental observations of organic radical reactivity in the gas phase. The reactivity of these radicals in the condensed organic phase, however, is poorly understood due to a lack of experimental observations. Additional and potentially important reactions not accessible in the gas phase are possible in the bulk organic phase, including bimolecular reactions. Here we consider the reactions of long chain alkoxy radicals generated by the photolysis of corresponding alkyl nitrites within organic matrices. Experiments were conducted in both bulk organic solvents (followed by atomization to aerosol instrumentation), as well as a smog chamber within submicron isotopically labeled squalane particles. Characterization of the chemical composition was completed with on-line measurements using the Aerodyne High Resolution Time of Flight Aerosol Mass Spectrometer. We observed the formation of an alcohol species, indicative of a bimolecular H-abstraction reaction with the bulk organic phase. Spectral subtraction of the alcohol mass spectrum from that of the bulk allows for determination of the branching ratios for unimolecular and bimolecular pathways. The identification and evolution of key product ions from unimolecular reactions as well as changes to the elemental ratios (O/C, H/C, N/C) of the products provides additional insight into the major pathways influencing in-particle oxidation processes.