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Factors Influencing the Formation of Nitrous Acid from Photolysis of Particulate Nitrate

Sommariva, Roberto; Alam, M. S.; Crilley, L. R.; Rooney, D. J.; Bloss, W. J.; Fomba, K. W.; Andersen, S. T.; Carpenter, L. J.

Authors

Roberto Sommariva

L. R. Crilley

W. J. Bloss

K. W. Fomba

S. T. Andersen

L. J. Carpenter



Abstract

Enhanced photolysis of particulate nitrate (pNO3) to form photolabile species, such as gas-phase nitrous acid (HONO), has been proposed as a potential mechanism to recycle nitrogen oxides (NOx) in the remote boundary layer (“renoxification”). This article presents a series of laboratory experiments aimed at investigating the parameters that control the photolysis of pNO3 and the efficiency of HONO production. Filters on which artificial or ambient particles had been sampled were exposed to the light of a solar simulator, and the formation of HONO was monitored under controlled laboratory conditions. The results indicate that the photolysis of pNO3 is enhanced, compared to the photolysis of gas-phase HNO3, at low pNO3 levels, with the enhancement factor reducing at higher pNO3 levels. The presence of cations (Na+) and halides (Cl-) and photosensitive organic compounds (imidazole) also enhance pNO3 photolysis, but other organic compounds such as oxalate and succinic acid have the opposite effect. The precise role of humidity in pNO3 photolysis remains unclear. While the efficiency of photolysis is enhanced in deliquescent particles compared to dry particles, some of the experimental results suggest that this may not be the case for supersaturated particles. These experiments suggest that both the composition and the humidity of particles control the enhancement of particulate nitrate photolysis, potentially explaining the variability in results among previous laboratory and field studies. HONO observations in the remote marine boundary layer can be explained by a simple box-model that includes the photolysis of pNO3, in line with the results presented here, although more experimental work is needed in order to derive a comprehensive parametrization of this process.

Citation

Sommariva, R., Alam, M. S., Crilley, L. R., Rooney, D. J., Bloss, W. J., Fomba, K. W., Andersen, S. T., & Carpenter, L. J. (2023). Factors Influencing the Formation of Nitrous Acid from Photolysis of Particulate Nitrate. Journal of Physical Chemistry A, 127(44), 9302–9310. https://doi.org/10.1021/acs.jpca.3c03853

Journal Article Type Article
Acceptance Date Oct 10, 2023
Online Publication Date Oct 25, 2023
Publication Date Nov 9, 2023
Deposit Date Oct 26, 2023
Publicly Available Date Oct 31, 2023
Journal The Journal of Physical Chemistry A
Print ISSN 1089-5639
Electronic ISSN 1520-5215
Publisher American Chemical Society
Peer Reviewed Peer Reviewed
Volume 127
Issue 44
Article Number 1
Pages 9302–9310
DOI https://doi.org/10.1021/acs.jpca.3c03853
Keywords Physical and Theoretical Chemistry
Public URL https://nottingham-repository.worktribe.com/output/26532465
Publisher URL https://pubs.acs.org/doi/10.1021/acs.jpca.3c03853

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