Atmospheric Chemistry

Heterogeneous, or mixed-phase, reactions that occur in atmospheric aerosol particles are of critical importance to the atmosphere and are a crucial component of chemical reaction cycles associated with Arctic and Antarctic ozone loss, tropospheric ozone production, and acid rain. Despite the importance of heterogeneous reactions, our knowledge and ability to predict the outcomes of these reactions is limited by the complexity of the environment in which they occur. Interfaces, the boundaries between chemical phases, possess unique chemical rules that cannot be described by the extension of gas- or liquid-phase properties. In few cases are the differences in chemical properties between the interface and solution phase starker than the distribution of ions. A considerable body of literature has shown that ions are preferentially allocated to the interface, in contrast to the uniform ion distributions associated with solution phase. As ions are prevalent in large concentrations in aerosol particles throughout the atmosphere, the buildup of ions in the interfaces of aerosols could have a substantial impact on heterogeneous reactions. We employ a variety of spectroscopic techniques centered on the use of reverse micelles in solution as proxies for sea spray aerosol particles to quantify the interfacial properties (structure and concentration) of ions. Our experimental work is combined with computational work by Dr. Arun Sharma at Wagner College to assemble a comprehensive chemical description of ions within the unique environment of the interfacial region. This project is supported by the National Science Foundation Environmental Chemical Sciences Program.