Prof. Dr. Jahan Dawlaty, University of Southern California, USA

Controlling Electric Fields and Ionic Profiles at Chemical Interfaces

Controlling the chemical microenvironments at an interface is a central goal of surface chemistry and more specifically electrochemistry. The interface is known to behave quite differently from the bulk, both in its physical and chemical properties. A quantity of central importance in electrochemistry is the interfacial electric field, which is closely related to the electric double layer structure. The interfacial fields act as polarizing agents for catalyzing reactions and are important for selectivity, ion transport, and lowering charge transfer barriers. We use vibrational Stark shift spectroscopy to measure such fields in an array of complex environments including the interface between electrodes and solvents, surfactants, and ionic liquids. Using these vibrational probes, we answer questions such as: How is the dielectric solvation different at the interface? How is proton transfer affected by the solvent and the interfacial field? How can one tailor and engineer the interfacial fields for specific purposes? What is the balance between hydrophobic forces and electrostatic forces in dictating interfacial fields? How can one control ion desolvation at the interface? These are some of the fundamental questions that will be discussed and their relevance to modern challenges in chemistry highlighted.