How important is molecular structure in the atmospheric chemistry and impacts of organic compounds?

The atmosphere contains thousands or tens of thousands of different organic compounds in both the gas and particle-phase. These compounds, and the products formed through their atmospheric chemical reactions, contribute substantially to global mortality, diminish global agricultural output, and drive substantial but uncertain climate effects. Most of the reactive organic carbon in the atmosphere is emitted in the form of a small number of molecules and compound classes, which undergo sunlight-drive oxidation processes in the atmosphere to form the dynamic and complex mixture of compounds observed.

To tackle this analytical challenge, a wide range of measurement techniques and modeling frameworks have been developed that classify compounds by their physicochemical properties and/or their molecular formulas. Such approaches necessarily gloss over (or outright ignore) the structure of a molecule, despite the critical role structure can play in the transformations and impacts of a compounds. However, little work has examined the prevalence of compounds that differ only in their molecular structure (i.e., isomers), or the extent to which ignoring structure degrades understanding of the sources, transformations, and fates of organic compounds in the atmosphere.

This presentation will examine the prevalence of isomers in the atmosphere, where they come from, and the extent to which knowing their structures may improve understanding of their chemistry. New instrumental and analytical methods will be presented to better characterize the structures of compounds emitted as parts of complex mixtures and quantify the diversity of molecular structures in the atmosphere. The physicochemical properties of different isomers will be compared to quantitatively understand differences in their atmospheric transformations, and estimate the impacts of these differences on the fates of molecules. Finally, specific case studies will be explored in which the structures of reactive organic compounds in the atmosphere play a critical role in their impacts on atmospheric oxidation chemistry, aerosol formation, and ecological impacts.