Atmos. Chem. Phys. Discuss., 11, 13693-13721, 2011
www.atmos-chem-phys-discuss.net/11/13693/2011/
doi:10.5194/acpd-11-13693-2011
© Author(s) 2011. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal Atmospheric Chemistry and Physics (ACP). Please refer to the corresponding final paper in ACP.
Fragmentation vs. functionalization: chemical aging and organic aerosol formation
H. J. Chacon-Madrid and N. M. Donahue
Center for Atmospheric Particle Studies, Carnegie Mellon Univ., Pittsburgh, PA 15213, USA

Abstract. The transformation process that a carbon backbone undergoes in the atmosphere is complex and dynamic. Understanding all these changes for all the species in detail is impossible; however, choosing different molecules that resemble progressively higher stages of oxidation or aging and studying them can give us an insight into general characteristics and mechanisms. Here we determine secondary organic aerosol (SOA) mass yields of two sequences of molecules reacting with the OH radical at high NOx. Each sequence consists of species with similar vapor pressures but a succession of oxidation states. The first sequence consists of n-pentadecane, n-tridecanal, 2-, 7-tridecanone, and pinonaldehyde. The second sequence consists of n-nonadecane, n-heptadecanal and cis-pinonic acid. Oxidized molecules tend to have lower relative SOA mass yields; however, oxidation state alone was not enough to predict how efficiently a molecule forms SOA. Certain functionalities are able to fragment more easily than others, and even the position of these functionalities on a molecule can have an effect. n-Alkanes tend to have the highest yields, and n-aldehydes the lowest. n-Ketones have slightly higher yields when the ketone moiety is located on the side of the molecule and not in the center. In general, oxidation products remain efficient SOA sources, though fragmentation makes them less effective than comparable alkanes.

Citation: Chacon-Madrid, H. J. and Donahue, N. M.: Fragmentation vs. functionalization: chemical aging and organic aerosol formation, Atmos. Chem. Phys. Discuss., 11, 13693-13721, doi:10.5194/acpd-11-13693-2011, 2011.
 
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