Phys.org April 7, 2023
Hydroxyl radical (OH) is a key oxidant that triggers atmospheric oxidation chemistry in both gas and aqueous phases. The current understanding of its aqueous sources is mainly based on known bulk (photo) chemical processes, uptake from gaseous OH, or related to interfacial O3 and NO3 radical-driven chemistry. An international team of researchers (France, USA – UC Irvine, Israel) has provided experimental evidence that OH radicals are spontaneously produced at the air–water interface of aqueous droplets in the dark and the absence of known precursors, possibly due to the strong electric field that forms at such interfaces. The measured OH production rates in atmospherically relevant droplets were comparable to or significantly higher than those from known aqueous bulk sources, especially in the dark. Based on their work the researchers concluded that aqueous droplets are ubiquitous in the troposphere, and this interfacial source of OH radicals should significantly impact atmospheric multiphase oxidation chemistry, with substantial implications on air quality, climate, and health… read more. TECHNICAL ARTICLE
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