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Shedding light on photosensitized reactions within marine-relevant organic thin films

TitleShedding light on photosensitized reactions within marine-relevant organic thin films
Publication TypeJournal Article
Year of Publication2019
AuthorsTrueblood J.V, Alves M.R, Power D., Santander M.V, Cochran R.E, Prather KA, Grassian VH
Date Published2019/08
Type of ArticleArticle
ISBN Number2472-3452
Accession NumberWOS:000492426500023
Keywordsaerosols; chemistry; extraction; Geochemistry & Geophysics; humic acids; marine-derived dissolved; matter; ocean; organic matter (m-DOM); photochemistry; photosensitized reactions; sea surface microlayer (SSML)

Photochemical processes drive much of the daytime gas-phase chemistry in the atmosphere. Within condensed phases, such as aerosol particles and thin films enriched in organics, much less is understood about these processes. An investigation aimed at better understanding photosensitized reactions that can occur within marine-relevant condensed-phase systems is described herein. In particular, photosensitized reactions have been investigated between a fatty acid model system and different photosensitizers within thin organic films representative of molecular species found in the sea surface microlayer and sea spray aerosols. Photosensitized reactions of thin films containing nonanoic acid and three different photosensitizers, including 4-benzoylbenzoic acid, humic acid, and marine-derived dissolved organic matter, were probed using a suite of analytical techniques, including vibrational spectroscopy, excitation-emission matrix spectroscopy, and ultra-high-resolution mass spectrometry. Considerable differences were found in the photosensitizing capability for each of these systems. We also present an analysis of the molecular differences between the different photosensitizers to explain their unique characteristics and light-absorbing properties. Overall, this study sheds light on the relevance of such reactions in the marine environment.

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