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Atmospheric aerosols facilitate reactions between ambient gases and dissolved species. Here, we review our efforts to interrogate the uptake of these gases and the mechanisms of their reactions both theoretically and experimentally. We highlight the fascinating behavior of N2O5 in solutions ranging from pure water to complex mixtures, chosen because its aerosol-mediated reactions significantly impact global ozone, hydroxyl, and methane concentrations. As a hydrophobic, weakly soluble, and highly reactive species, N2O5 is a sensitive probe of the chemical and physical properties of aerosol interfaces. We employ contemporary theory to disentangle the fate of N2O5 as it approaches pure and salty water, starting with adsorption and ending with hydrolysis to HNO3, chlorination to ClNO2, or evaporation. Flow reactor and gas-liquid scattering experiments probe even greater complexity as added ions, organic molecules, and surfactants alter the interfacial composition and reaction rates. Together, we reveal a new perspective on multiphase chemistry in the atmosphere.
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Multiphase chemistry in the troposphere: It all starts … and ends … with gases
Abstract When the phenomena of smog and acid deposition were first recognized, it was largely gas phase chemists and photochemists who leapt into the fray to untangle the sources and chemistry involved. Over time, the importance of multiphase chemistry was recognized, as illustrated in a dramatic manner with the discovery of the Antarctic ozone hole which is driven by heterogeneous chemistry on polar stratospheric clouds. Since then, it has become clear that multiphase chemistry is central to both the lower and upper atmosphere and that this deeply intertwines interactions between the gas and condensed phases in the atmosphere. As a result, it can be argued that multiphase atmospheric chemistry begins … and ends… with gases. This paper is based on the 2018 Polanyi Medal award presentation at the 25th International Symposium on Gas Kinetics & Related Phenomena and traces research carried out in the author's laboratory on multiphase chemistry over a number of decades. While a great deal has been learned about these processes, they remain one of the areas of greatest uncertainty in understanding atmospheric composition, air quality, chemistry, and climate change.
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- Award ID(s):
- 1647386
- PAR ID:
- 10371760
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- International Journal of Chemical Kinetics
- Volume:
- 51
- Issue:
- 10
- ISSN:
- 0538-8066
- Page Range / eLocation ID:
- p. 736-752
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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