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Microheterogeneous singlet oxygen generation at air-water interfaces.

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Bibliographic Details
Title:	Microheterogeneous singlet oxygen generation at air-water interfaces.
Authors:	Mi, Shaoping¹, Fang, Ye-Guang², Liu, Xiaochen¹, Zheng, Xiaoshan¹, Ming, Hongbo¹, Li, Xiaojiao², Chen, Baoliang¹, Zhu, Chongqin², McNeill, Kristopher³, Chu, Chiheng¹ chuchiheng@zju.edu.cn
Source:	Proceedings of the National Academy of Sciences of the United States of America. 4/7/2026, Vol. 123 Issue 14, p1-8. 41p.
Subjects:	Gas-liquid interfaces, Microdroplets, Aerosols, Oxidation, Organic compounds, Reactive oxygen species, Reaction-diffusion equations, Photochemistry
Abstract:	Singlet oxygen (¹O2) is a short-lived, highly reactive oxidant driving natural element cycles, yet its spatial distribution in complex multiphase systems remains poorly understood. Here, we show that irradiation of organic carbon (OC)-containing aqueous microdroplets leads to pronounced interfacial enrichment of ¹O2, driven by the surface accumulation of photosensitizing OC. Combining fluorescence imaging with a reaction-diffusion kinetic model, we resolve steep ¹O2 gradients across the air-water boundary: In a 1 μm-radius droplet, ¹O2 levels drop by 90% within 10 μm from the interface into the gaseous phase, and within 230 nm from the interface into the aqueous phase. Tailored peptide probes reveal that molecules residing at the interface undergo substantially faster ¹O2-mediated transformation than their bulk counterparts. These findings identify the air-water interface as a privileged site for ¹O2 photochemistry that strongly accelerates redox processes in aerosols, sea spray, and the ocean-atmosphere boundary. [ABSTRACT FROM AUTHOR]
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Database:	Engineering Source

Description
Abstract:	Singlet oxygen (¹O2) is a short-lived, highly reactive oxidant driving natural element cycles, yet its spatial distribution in complex multiphase systems remains poorly understood. Here, we show that irradiation of organic carbon (OC)-containing aqueous microdroplets leads to pronounced interfacial enrichment of ¹O2, driven by the surface accumulation of photosensitizing OC. Combining fluorescence imaging with a reaction-diffusion kinetic model, we resolve steep ¹O2 gradients across the air-water boundary: In a 1 μm-radius droplet, ¹O2 levels drop by 90% within 10 μm from the interface into the gaseous phase, and within 230 nm from the interface into the aqueous phase. Tailored peptide probes reveal that molecules residing at the interface undergo substantially faster ¹O2-mediated transformation than their bulk counterparts. These findings identify the air-water interface as a privileged site for ¹O2 photochemistry that strongly accelerates redox processes in aerosols, sea spray, and the ocean-atmosphere boundary. [ABSTRACT FROM AUTHOR]
ISSN:	00278424
DOI:	10.1073/pnas.2534956123