Collaborative Research: RUI: Elucidating Ion Interactions at Interfaces through Synergistic Experiments and Simulations

With support from the Environmental Chemical Sciences (ECS) program in the Division of Chemistry, Joshua D. Patterson at Christopher Newport University and Arunkumar Sharma at California State University Monterey Bay and their undergraduate researchers will use a combined spectroscopic and computational approach to examine the properties that control the distribution and identities of ions at interfaces. Ions are commonly found in high concentrations within aerosols in the atmosphere and participate in various mixed-phase reactions. The accurate prediction of atmospheric chemistry requires precise knowledge of the arrangement of ions at interfaces and the properties that drive these arrangements. This project aims to investigate how molecular interactions and ionic charge influence the preferences of ions for the interface and determine the properties that dictate ion pair formation. Through collaborative experiences and complementary computational and spectroscopic studies, undergraduate researchers at both public institutions will gain invaluable practical skills that are transferable to future careers in science. Non-uniform distributions of ions at interfaces have the potential to suppress or enhance heterogeneous reactions beyond the levels indicated by the ionic concentrations within the bulk of aerosols. Despite the importance of heterogeneous reactions, the chemical properties that ultimately direct the distribution of ions within the interface remain unresolved. This project aims to quantify the interfacial affinities of ions using infrared spectroscopy, molecular dynamics simulations, and quantum chemical calculations. Mapping interfacial affinities in terms of hydrogen-bonding capacity and electrostatic properties has the potential to reveal the chemical properties that direct interfacial distributions and speciation. These studies aim to produce quantitative estimates of the reactive availabilities of ions, enhancing the accuracy of atmospheric models, and providing critical data to inform and shape policies on emission standards. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.