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Title: Peroxy radical kinetics and new particle formation
Chamber experiments showing “pure biogenic nucleation” have shown an important role for covalently bound organic association products (“dimers”). These form from peroxy-radical (RO 2 ) cross reactions. Chamber experiments at low-NO x conditions often have quite high hydrocarbon reactant concentrations and relatively low concentrations of oxygenated volatile organic compounds (OVOCs). This can skew the radical chemistry in chambers relative to the real atmosphere, favoring RO 2 and disfavoring HO 2 radicals. RO 2 cross reaction kinetics are in turn highly uncertain. Here we explore the implications of the RO 2 to HO 2 ratio in chamber experiments as well as the implications of uncertain RO 2 cross reaction kinetics and the potential for added CO to mimic more atmospheric radical conditions. We treat a plausible range of RO 2 rate coefficients under both typical chamber conditions and atmospheric conditions to see how dimerization is affected by high concentrations of OVOCs, and thus lower RO 2  : HO 2 relative to smog chamber experiments. We find that if RO 2 reactions are fast, relatively high yields of low volatility dimers can participate in new particle formation. The results are highly sensitive to both the (uncertain) RO 2 kinetics as well as RO 2  : HO 2 , suggesting both that low-NO x chamber results should be extrapolated to the atmosphere with caution but also that the atmosphere itself may be highly sensitive to the specific (and rich) mixture of organic compounds and thus peroxy radicals.  more » « less
Award ID(s):
1801897
PAR ID:
10282691
Author(s) / Creator(s):
;
Date Published:
Journal Name:
Environmental Science: Atmospheres
Volume:
1
Issue:
2
ISSN:
2634-3606
Page Range / eLocation ID:
79 to 92
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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