Faculty of Graduate Studies
Graduate Programme in Chemistry
ORAL EXAMINATION PROSPECTUS
A Candidate for the Degree of
Master of Science.
Title of Thesis:
Investigation of Isoprene OH initiated Photo-Oxidation Mechanism and Secondary Organic Aerosol Formation in Presence of High NOx
May 16, 2012 @ 10:00 am – 10:45 am
115 Chemistry Building
York University
Abstract: It is now well recognized that a wide variety of volatile organic compounds (VOCs) are emitted into the atmosphere from both biogenic and anthropogenic sources. Isoprene is the most abundant BVOCs in regional and global scale, emitted mainly from vegetation. The purpose of this work was to investigate isoprene OH initiated photo-oxidation mechanism and Secondary Organic Aerosol (SOA) formed during Smog Chamber experiments, in presence of high NOx level. The gas phase products of isoprene oxidation are analyzed using Ion Trap –Time Of Flight Mass Spectrometer. We used “de-synthesis of spectra” approach to separate the mass spectra for individual components. This enabled us to follow all major reaction products in course of experiment, quantify yields and calculate rate constant for MVK and MACR. Our experiments showed that photo-oxidation of isoprene leads to SOA formation but over delayed timescale. The role of methacrolein as an intermediate to aerosol formation is discussed and quantified. The contribution of methacrolein to total volume of aerosol formed is estimated to be 2% to 21%, which represents a small fraction of total volume formed and suggests that other contributors and pathways should be considered and elaborated. The role of hydroxycarbonyl compounds and their likely role in forming particulate matter is also investigated and discussed.