AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Photolysis of Aldehydes in Organic Matrices as a Model for Photolytic Processing of Organic Aerosols
SANDRA BLAIR, Dorit Shemesh, Benny Gerber, Adam Bateman, Sergey Nizkorodov, University of California, Irvine
Abstract Number: 257 Working Group: Aerosol Chemistry
Abstract Organic aerosols (OA) represent a major component of the atmospheric particulate matter. While the gas-phase photochemical processes leading to the formation of OA have been studied for a number of years, the importance of condensed-phase photochemistry occurring inside atmospheric OA has not been recognized until recently. The mechanisms of even the simplest condensed-phase photochemical processes, the effect of the organic matrix on these processes, and the role of direct vs. indirect photolysis in aging of OA are currently unknown. Our goal is to investigate the condensed-phase chemistry of carbonyl compounds and common constituents of OA embedded into organic matrices that appropriately mimic OA material. Saturated linear aldehydes, such as undecanal, are used as model systems. Our approach is to conduct detailed experiments on gas-phase and condensed phase photochemistry of selected aldehydes and carry out detailed ab initio calculations of their photochemical properties. We will report experiments on photolysis of pure liquid and solid undecanal studied with a combination of GCMS and UVVIS methods. We also present experimental data on gas-phase photolysis of undecanal studied with proton-transfer reaction mass spectrometry for comparison. The experimentally measured photolysis quantum yields and mechanisms will be compared with those predicted by the state-of-the-art on-the-fly photodissociation dynamics ab initio calculations in both gas and condensed phases. The relevance of these results for aging of OA under different atmospheric scenarios will be discussed.