Secondary organic aerosol yields of 12-carbon alkanes
Item
Title (Dublin Core)
Secondary organic aerosol yields of 12-carbon alkanes
Description (Dublin Core)
Secondary organic aerosol (SOA) yields were measured for cyclododecane, hexylcyclohexane, n-dodecane, and 2-methylundecane under high-NO<sub>x</sub> conditions, in which alkyl proxy radicals (RO<sub>2</sub>) react primarily with NO, and under low-NO<sub>x</sub> conditions, in which RO<sub>2</sub> reacts primarily with HO<sub>2</sub>. Experiments were run until 95–100% of the initial alkane had reacted. Particle wall loss was evaluated as two limiting cases using a new approach that requires only suspended particle number-size distribution data and accounts for size-dependent particle wall losses and condensation. SOA yield differed by a factor of 2 between the two limiting cases, but the same trends among alkane precursors were observed for both limiting cases. Vapor-phase wall losses were addressed through a modeling study and increased SOA yield uncertainty by approximately 30%. SOA yields were highest from cyclododecane under both NO<sub>x</sub> conditions. SOA yields ranged from 3.3% (dodecane, low-NO<sub>x</sub> conditions) to 160% (cyclododecane, high-NO<sub>x</sub> conditions). Under high-NO<sub>x</sub> conditions, SOA yields increased from 2-methylundecane < dodecane ~ hexylcyclohexane < cyclododecane, consistent with previous studies. Under low-NO<sub>x</sub> conditions, SOA yields increased from 2-methylundecane ~ dodecane < hexylcyclohexane < cyclododecane. The presence of cyclization in the parent alkane structure increased SOA yields, whereas the presence of branch points decreased SOA yields due to increased vapor-phase fragmentation. Vapor-phase fragmentation was found to be more prevalent under high-NO<sub>x</sub> conditions than under low-NO<sub>x</sub> conditions. For different initial mixing ratios of the same alkane and same NO<sub>x</sub> conditions, SOA yield did not correlate with SOA mass throughout SOA growth, suggesting kinetically limited SOA growth for these systems.
Creator (Dublin Core)
Loza, C. L.
Craven, J. S.
Yee, L. D.
Coggon, M. M.
Schwantes, R. H.
Shiraiwa, M.
Zhang, X.
Schilling, K. A.
Ng, N. L.
Canagaratna, M. R.
Ziemann, P. J.
Flagan, R. C.
Seinfeld, J. H.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-14-1423-2014
https://acp.copernicus.org/articles/14/1423/2014/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
