In:
Atmospheric Chemistry and Physics, Copernicus GmbH, Vol. 18, No. 4 ( 2018-02-19), p. 2363-2380
Abstract:
Abstract. Atmospheric oxidation is an important phenomenon which produces large
quantities of low-volatility compounds such as sulfuric acid and oxidized
organic compounds. Such species may be involved in the nucleation of particles
and enhance their subsequent growth to reach the size of cloud condensation
nuclei (CCN). In this study, we investigate α-pinene, the most
abundant monoterpene globally, and its oxidation products formed through
ozonolysis in the Cosmic Leaving OUtdoor Droplets (CLOUD) chamber at CERN
(the European Organization for Nuclear Research). By scavenging hydroxyl
radicals (OH) with hydrogen (H2), we were able to investigate the
formation of highly oxygenated molecules (HOMs) purely driven by ozonolysis
and study the oxidation of sulfur dioxide (SO2) driven by stabilized
Criegee intermediates (sCIs). We measured the concentrations of HOM and
sulfuric acid with a chemical ionization atmospheric-pressure interface
time-of-flight (CI-APi-TOF) mass spectrometer and compared the measured
concentrations with simulated concentrations calculated with a kinetic model.
We found molar yields in the range of 3.5–6.5 % for HOM formation and
22–32 % for the formation of stabilized Criegee intermediates by fitting
our model to the measured sulfuric acid concentrations. The simulated time
evolution of the ozonolysis products was in good agreement with measured
concentrations except that in some of the experiments sulfuric acid formation
was faster than simulated. In those experiments the simulated and measured
concentrations met when the concentration reached a plateau but the plateau
was reached 20–50 min later in the simulations. The results shown here are
consistent with the recently published yields for HOM formation from
different laboratory experiments. Together with the sCI yields, these results
help us to understand atmospheric oxidation processes better and make the
reaction parameters more comprehensive for broader use.
Type of Medium:
Online Resource
ISSN:
1680-7324
DOI:
10.5194/acp-18-2363-2018
Language:
English
Publisher:
Copernicus GmbH
Publication Date:
2018
detail.hit.zdb_id:
2092549-9
detail.hit.zdb_id:
2069847-1
