Organization, Hydration, Ion Speciation, and Inherent Electric Fields at Water Surfaces

Seminar | January 23 | 4-5 p.m. | 120 Latimer Hall

 Heather Allen, Department of Chemistry and Biochemistry, Ohio State University

 College of Chemistry

We investigate ions and lipids at aqueous surfaces to better understand their complexation and speciation to then inform on atmospheric aerosol, cloud, and marine surface processes. The underlying driving forces for surface activity of bare aqueous surfaces with salts such as iron, magnesium, calcium and sodium chlorides are one class that is explored with aqueous surface selective experimental tools. Research is presented on the aqueous salt surfaces revealing surface propensity of hydrated ions and ion pairs that dominate the interfacial response. In addition, studies of calcium-fatty acid surface complexation indicate that equilibrium and nonequilibrium results are vastly different. The surface electric field was measured using surface potentiometry with radioactive Americium, a new method in our laboratory. Surface tensiometry, Brewster angle microscopy, and vibrational probes of sum frequency generation (SFG), and infrared reflection absorption spectroscopy (IRRAS) were also used and data are presented to provide clarity on surface acidity, ionization state, ion-lipid and ion-ion speciation, and thermodynamic stability of aqueous films.

 Light refreshments will be served at 3:50 at The Coffee Lab, 510-643-0572