Isoprene NO3 Oxidation Products from the RO2 + HO2 Pathway.
We describe the products of the reaction of the hydroperoxy radical (HO(2)) with the alkylperoxy radical formed following addition of the nitrate radical (NO(3)) and O(2) to isoprene. NO(3) adds preferentially to the C(1) position of isoprene (>6 times more favorably than addition to C(4)), followed by the addition of O(2) to produce a suite of nitrooxy alkylperoxy radicals (RO(2)). At an RO(2) lifetime of ∼30 s, δ-nitrooxy and β-nitrooxy alkylperoxy radicals are present in similar amounts. Gas-phase product yields from the RO(2) + HO(2) pathway are identified as 0.75-0.78 isoprene nitrooxy hydroperoxide (INP), 0.22 methyl vinyl ketone (MVK) + formaldehyde (CH(2)O) + hydroxyl radical (OH) + nitrogen dioxide (NO(2)), and 0-0.03 methacrolein (MACR) + CH(2)O + OH + NO(2). We further examined the photochemistry of INP and identified propanone nitrate (PROPNN) and isoprene nitrooxy hydroxyepoxide (INHE) as the main products. INHE undergoes similar heterogeneous chemistry as isoprene dihydroxy epoxide (IEPOX), likely contributing to atmospheric secondary organic aerosol formation.
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Rebecca H
RH
Schwantes
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Alexander P
AP
Teng
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Tran B
TB
Nguyen
Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Matthew M
MM
Coggon
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
John D
JD
Crounse
Atmospheric Chemistry and Dynamics Laboratory, NASA Goddard Space Flight Center , Greenbelt, Maryland 20771, United States.|Joint Center for Earth Systems Technology, University of Maryland Baltimore County , Baltimore, Maryland 21250, United States.
Jason M
JM
St Clair
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Xuan
X
Zhang
Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Katherine A
KA
Schilling
Division of Chemistry and Chemical Engineering, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.|Division of Engineering and Applied Science, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
John H
JH
Seinfeld
Division of Geological and Planetary Sciences, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.|Division of Engineering and Applied Science, California Institute of Technology , 1200 East California Boulevard, Pasadena, California 91125, United States.
Paul O
PO
Wennberg