Reactions between Criegee Intermediates and the Inorganic Acids HCl and HNO₃: Kinetics and Atmospheric Implications

Abstract

Criegee intermediates (CIs) are a class of reactive radicals that are thought to play a key role in atmospheric chemistry through reactions with trace species that can lead to aerosol particle formation. Recent work has suggested that water vapor is likely to be the dominant sink for some CIs, although reactions with trace species that are sufficiently rapid can be locally competitive. Herein, we use broadband transient absorption spectroscopy to measure rate constants for the reactions of the simplest CI, CH2OO, with two inorganic acids, HCl and HNO3, both of which are present in polluted urban atmospheres. Both reactions are fast; at 295 K, the reactions of CH2OO with HCl and HNO3 have rate constants of 4.6×10−11 cm3 s−1 and 5.4×10−10 cm3 s−1, respectively. Complementary quantum‐chemical calculations show that these reactions form substituted hydroperoxides with no energy barrier. The results suggest that reactions of CIs with HNO3 in particular are likely to be competitive with those with water vapor in polluted urban areas under conditions of modest relative humidity.

Spectroscopic Characterization of the Reaction Products between the Criegee Intermediate CH2OO and HCl

“…TS1 obtained here differs from the transition state between the pre-reactive complex and CMHP found in Ref. 16, where it lies lower in energy than the HCl-CH 2 OO complex. This fact may be attributedt ot he small basis set employed in their calculations, cc-pVDZ.…”

Criegee Intermediate Reactions with Carboxylic Acids: A Potential Source of Secondary Organic Aerosol in the Atmosphere

“…Reaction rates of Criegee intermediates with HNO 3 and HCl have been shown to approach or exceed the gas kinetic limit. 49,50 Both reaction types are predicted to form hydroperoxide adduct products, similar to the reactions with carboxylic acids. The hydroperoxide adducts from reaction with hydrochloric and nitric acids also have chloro and nitrate functionalities, respectively, both of which are important in atmospheric chemistry.…”

The atmospheric impacts of monoterpene ozonolysis on global stabilised Criegee intermediate budgets and SO<sub>2</sub> oxidation: experiment, theory and modelling

“…Laboratory experiments and theoretical calculations have shown SCIs to oxidise SO 2 (e.g. Cox and Penkett, 1971;Welz et al, 2012;Taatjes et al, 2013), organic (Welz et al, 2014) and inorganic (Foreman et al, 2016) acids (Vereecken, 2017) and a number of other important trace gases found in the atmosphere, as well as forming adducts with NO 2 (Taatjes et al, 2014;Vereecken and Nguyen, 2017;Caravan et al, 2017). Measurements in a boreal forest (Mauldin III et al, 2012) and at a coastal site (Berresheim et al, 2014) have both identified a missing process (in addition to a reaction with OH) that oxidises SO 2 to H 2 SO 4 , potentially arising from SCI reactions.…”