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Titel |
Kinetic regimes and limiting cases of gas uptake and heterogeneous reactions in atmospheric aerosols and clouds: a general classification scheme |
VerfasserIn |
Thomas Berkemeier, Andrew J. Huisman, Markus Ammann, Manabu Shiraiwa, Thomas Koop, Ulrich Pöschl |
Konferenz |
EGU General Assembly 2013
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 15 (2013) |
Datensatznummer |
250076511
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Zusammenfassung |
Heterogeneous reactions are important to atmospheric chemistry and are therefore an area of
intense research. In multiphase systems such as aerosols and clouds, chemical reactions are
usually strongly coupled to a complex sequence of mass transport processes and results are
often not easy to interpret.
Here we present a systematic classification scheme for gas uptake by aerosol or
cloud particles which distinguishes two major regimes: a reaction-diffusion regime
and a mass-transfer regime. Each of these regimes includes four distinct limiting
cases, characterized by a dominant reaction location (surface or bulk) and a single
rate-limiting process: chemical reaction, bulk diffusion, gas-phase diffusion or mass
accommodation.
The conceptual framework enables efficient comparison of different studies and
reaction systems, going beyond the scope of previous classification schemes by
explicitly resolving interfacial transport processes and surface reactions limited by
mass transfer from the gas phase. The use of kinetic multi-layer models instead of
resistor model approaches increases the flexibility and enables a broader treatment of
the subject, including cases which do not fit into the strict limiting cases typical
of most resistor model formulations. The relative importance of different kinetic
parameters such as diffusion, reaction rate and accommodation coefficients in this
system is evaluated by a quantitative global sensitivity analysis. We outline the
characteristic features of each limiting case and discuss the potential relevance of different
regimes and limiting cases for various reaction systems. In particular, the classification
scheme is applied to three different data sets for the benchmark system of oleic acid
reacting with ozone. In light of these results, future directions of research needed to
elucidate the multiphase chemical kinetics in this and other reaction systems are
discussed.
Reference: Berkemeier, T., Huisman, A. J., Ammann, M., Shiraiwa, M., Koop, T., and
Pöschl, U.: Kinetic regimes and limiting cases of gas uptake and heterogeneous reactions in
atmospheric aerosols and clouds: a general classification scheme, Atmos. Chem. Phys.
Discuss., 13, 983-1044, doi:10.5194/acpd-13-983-2013, 2013. |
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