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.

The kinetics of the reactions of Br atoms with the xylenes: an experimental and theoretical study

“…The importance of reactions of atomic halogens to the chemistry of the atmosphere has been recognized for a long time. On the subject, recent reviews 1,2 provide a rich source of citations of the primary literature. The reactions of Cl, OH and Br are potentially involved in the photo-oxidation of volatile organic compounds (VOCs) in the atmosphere and have some similarities as well as significant differences in their reactivity.…”

A theoretical kinetic study on the reaction of atomic bromine with toluene

“…These observations sparked extensive research in the kinetics of halogen atom reactions, which led to a large database of kinetic data for halogen atom reactions 4–7 . In recent years, there have been several reviews of atmospheric halogen atom chemistry 8–11 . Much of the work has focused on reactions of halogen atoms with hydrocarbons near ambient temperature and pressure.…”

“…[4][5][6][7] In recent years, there have been several reviews of atmospheric halogen atom chemistry. [8][9][10][11] Much of the work has focused on reactions of halogen atoms with hydrocarbons near ambient temperature and pressure. Interestingly, more attention has been paid to the reactions of atomic chlorine than to the reactions of atomic bromine despite its importance to atmospheric chemistry in the Arctic.…”

Environment Effects on X-Ray Absorption Spectra With Quantum Embedded Real-Time Time-Dependent Density Functional Theory Approaches

“…To do so, we have extended our recently developed Psi4Numpy-based rt-TDDFT-in-DFT to implement the BOMME and rt-BOMME methods. As discussed below, in this manuscript we shall focus on the K and L 1 edges of hydrated halides, since halogenated species and their interaction with species in solution or at interfaces are of particular interest in atmospheric sciences ( Finlayson-Pitts, 2013 ; Pillar-Little et al, 2013 ; Simpson et al, 2015 ; Kong et al, 2017 ; Finlayson‐Pitts, 2019 ; Bartels-Rausch et al, 2021 ; Yu and Li, 2021 ). Here, however, in order to simplify our discussion we have considered relatively simple model systems representing the first hydration shell of the halides ( and ) that nevertheless can gauge the ability of the different embedding methods to describe interactions of varying strengths between halides and their environment.…”