Secondary organic aerosol (SOA) formation from reaction of isoprene with nitrate radicals (NO_3)

Ng, N. L.
Kwan, A. J.
Surratt, J. D.
Chan, A. W. H.
Chhabra, P. S.
Sorooshian, A.
Pye, H. O. T.
Crounse, J. D.
Wennberg, P. O.
Flagan, R. C.
Seinfeld, J. H.

Publication date

February 2008

Publisher

European Geosciences Union

Abstract

Secondary organic aerosol (SOA) formation from the reaction of isoprene with nitrate radicals (NO3) is investigated in the Caltech indoor chambers. Experiments are performed in the dark and under dry conditions (RH<10%) using N2O5 as a source of NO3 radicals. For an initial isoprene concentration of 18.4 to 101.6 ppb, the SOA yield (defined as the ratio of the mass of organic aerosol formed to the mass of parent hydrocarbon reacted) ranges from 4.3% to 23.8%. By examining the time evolutions of gas-phase intermediate products and aerosol volume in real time, we are able to constrain the chemistry that leads to the formation of low-volatility products. Although the formation of ROOR from the reaction of two peroxy radicals (RO2) has generall...