Department Seminar

Upcoming Seminar

Photochemistry in Natural and Engineered Environmental Systems
Dr. Garrett McKay, Texas A&M University

April 24, 2024
4:00pm-5:00pm in HSCI-105

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The chemical structure of chromophores in dissolved organic matter (DOM) governs the mechanisms and rates of key processes in aquatic systems—elemental cycles, attenuation of contaminants, and productivity of the Earth's oceans, among others. Despite the importance of DOM chromophores, knowledge of the molecular-level phenomena that shape DOM's optical and photochemical properties remains elusive. A crucial step to obtaining this knowledge is to elucidate the chemical composition and quantitative contribution of charge-transfer complexes (non-covalent interactions between molecules that produce new, lower-energy electronic transitions) to DOM absorbance, fluorescence, and photochemistry. This presentation will describe my group's efforts to address this knowledge gap using a variety of approaches, including (i) selective reduction of chromophores in DOM with sodium borohydride, (ii) using autoxidized hydroquinone as a "bottom up" approach to test the charge-transfer model, and (iii) comparison of aquatic DOM to other carbon-based nanostructures (i.e., atmospheric brown carbon and eumelanin). These results will be used to discuss the importance of both specific functional groups and three-dimensional structure in governing DOM photophysical properties.

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