Journal of the American Chemical Society· 2025Q1
Simultaneous Reduction and Oxidation of NO 2 on Water Microdroplets Provides Previously Unknown Pathways to the Formation of HONO and HNO 3
- 24citations
- Q1SCImago
- 2025year
Short summary
Water microdroplets in the presence of NO2 simultaneously form HONO and HNO3 via reduction and oxidation pathways driven by electrons and hydroxyl radicals generated at the air-water interface.
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Key points
- HONO and HNO3 are simultaneously formed from NO2 on water microdroplets.
- Formation occurs via reduction of NO2 to HONO and oxidation to HNO3.
- Electrons and hydroxyl radicals, generated by electric fields at the air-water interface, drive these reactions.
- Tandem mass spectrometry, isotope labeling, and chemical ionization confirmed product formation.
AI-generated from the title and abstract; the full text is not read.
Abstract
HONO and HNO 3 are important atmospheric species, yet their formation pathways in the atmosphere remain uncertain. In this study, we report the simultaneous formation of HONO and HNO 3 at the air–water interface of water microdroplets in the presence of trace amounts of NO 2 . Water microdroplets were generated either in ambient air or in a glovebox where the gas content could be precisely controlled. The products generated by the microdroplets and surrounding gas were directly analyzed with mass spectrometers. Our results indicated that NO 2 gas could be reduced by an electron to form NO 2 –, which was further protonated to yield HONO, or could be oxidized by a hydroxyl radical (·OH) to form HNO 3 . Electrons and ·OH were produced by a strong electric field that facilitated OH – dissociation at the air–water interface of the microdroplets. Tandem mass spectrometry, isotope labeling, and chemical ionization methods confirmed the formation of neutral HONO and HNO 3 . Our results provide a previously unknown pathway for the formation of HONO and HNO 3 in the troposphere.
The authors' abstract, as published at the source. Journal of the American Chemical Society, 2025 · DOI ↗
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Field: Atmospheric Science
Atmospheric ScienceEarth and Planetary Sciences