Characterization and Quantification of Particle-Bound Criegee Intermediates in Secondary Organic Aerosol

Abstract

The ozonolysis of alkenes contributes substantially to the formation of secondary organic aerosol (SOA), which are important modulators of air quality and the Earth’s climate. Criegee intermediates (CIs) are abundantly formed through this reaction. However, their contributions to aerosol particle chemistry remain highly uncertain. In this work, we present the first application of a novel methodology, using spin traps, which simultaneously quantifies CIs produced from the ozonolysis of volatile organic compounds in the gas and particle phases. Only the smallest CI with one carbon atom was detected in the gas phase of a β-caryophyllene ozonolysis reaction system. However, multiple particle-bound CIs were observed in β-caryophyllene SOA. The concentration of the most abundant CI isomer in the particle phase was estimated to constitute ∼0.013% of the SOA mass under atmospherically relevant conditions. We also demonstrate that the lifetime of CIs in highly viscous SOA particles is at least on the order of minutes, substantially greater than their gas-phase lifetime. The confirmation of substantial concentrations of large CIs with elongated lifetimes in SOA raises new questions regarding their influence on the chemical evolution of viscous SOA particles, where CIs may be a previously underestimated source of reactive species.

Partitioning of reactive oxygen species from indoor surfaces to indoor aerosols

“…These organic compounds are likely to have a relatively low volatility since they are already present in the film, and therefore it is quite likely that the secondary ozonide and hydroperoxide products will also be of low volatility. 87 Carboxylic acids are present at high concentrations in skin oil and will react with Criegee intermediates forming α-acyloxy hydroperoxides. 88–90 Palmitic acid is the most common fatty acid in human skin and is likely to react with Criegee intermediates formed by squalene ozonolysis, leading to a variety of products such as those listed in Table S1 † 88,90 .…”

Constraining the Reaction Rate of Criegee Intermediates with Carboxylic Acids during the Multiphase Ozonolysis of Aerosolized Alkenes

“…As this is several orders of magnitude smaller than the combined CI loss rate (second term of Eq ), thought to be on the order of 10 2 s –1 , the CIs are expected to reach their maximum concentration rapidly. Recent experimental evidence has indicated that CIs remain detectable for minutes after their formation in viscous secondary organic aerosol, longer than the 39 s flow tube residence time in this work, suggesting that the CI population may not deviate far from a steady-state concentration over the duration of the measurements reported here. In addition, as discussed in Section , the results of this simple kinetic model agree with explicit kinetic simulations where no such steady-state assumptions are made.…”

Characterizing Hydroxyl Radical Formation from the Light-Driven Fe(II)–Peracetic Acid Reaction, a Key Process for Aerosol-Cloud Chemistry

“…Given its extremely rapid reaction with Fe­(II), however, it seems likely that it should be consumed as soon as it is absorbed. Highly viscous aerosol particles can potentially stabilize reactive species, , and thus, the concentration of PAA or other organic peracids present in an aerosol may be higher immediately after the particle dissolves upon activation to become a cloud droplet. While not yet investigated, it is also possible that the “burst” chemistry takes place in particles when they deliquesce.…”

“…Organic peracids have been detected in biogenic and anthropogenic SOA; they are multigeneration oxidation products in ambient SOA, formed when volatile organic compounds are oxidized by OH or O 3 . While they are relatively reactive, reactive species have been shown to be preserved in viscous SOA particles . This could preserve substantial concentrations of peracids, which upon interaction with a cloud droplet, liberate peracids upon dissolution, which in the presence of Fe­(II) (which has a typical concentration of 10 –7 – 10 –4 M in ambient cloudwater) represents an additional large source of OH in cloudwater .…”

“…While they are relatively reactive, reactive species have been shown to be preserved in viscous SOA particles. 56 This could preserve substantial concentrations of peracids, which upon interaction with a cloud droplet, liberate peracids upon dissolution, which in the presence of Fe(II) (which has a typical concentration of 10 –7 – 10 –4 M in ambient cloudwater) represents an additional large source of OH in cloudwater. 23 Fang et al recently observed enhanced OH formation (although not an OH burst) from Fenton-like reactions of isoprene hydroxy hydroperoxide from isoprene SOA, demonstrating that SOA components can engage in Fenton chemistry at faster rates than Fe(II) + H 2 O 2 .…”