Atmospheric New Particle Formation is the process by which atmospheric trace gases, typically sulfuric acid, amines, and organic acids, cluster and grow to climatically-relevant sizes. We are interested in how intermolecular interactions, particularly hydrogen bonding and proton transfer, govern the mechanisms of particle formation and growth. Typical atmospheric instrumentation provides little molecular detail for clusters of only a few nanometers, leaving significant unanswered questions regarding the role of water and structure in determining growth rates. We are using variable-temperature ion trap mass spectrometry and vibrational spectroscopy to evaluate the surface structure of these clusters, their hydration state, and the interplay of intermolecular forces in governing these properties. We have developed models that maintain critical structural information without requiring the exact structure to be known, and that predict the hydration of these clusters, a major unknown aspect of this problem. These insights serve as foundations for our further studies of the growth mechanism and provide critical molecular-level benchmarks for theoretical efforts to model this process in atmospheric conditions.

Vibrational manifestations of acid-base chemistry in atmospheric clusters

2019 Spring National Meeting

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