Interfacial Fields Measured by Vibrational Sum Frequency Generation at Electrode-Electrolyte and Electrode-Ionic Liquid Interfaces
Abstract
Interfacial electric fields are important in several areas of chemistry, materials sciences, and device physics. However, they are poorly understood, partly because they are difficult to measure directly and model accurately. We propose a comprehensive investigation of such fields using Vibrational Sum Frequency Generation (VSFG) Stark shift spectroscopy.Solvation Fields at an interface: We will build upon our recently successful model and experiments that extend the conventional bulk Onsager solvation field theory to the interface. The solvation field is the field that a molecule feels due to the polarization that it induces on its environment. This type of field leads to Stark shifts on vibrational chromophores, and has been measured in enzymes and correlated with their activity using bulk spectroscopy. We will perform SFG experiments on vibrational Stark reporters at interfaces to measure such fields and correlate them with interfacial properties. We will take full account of specific interactions such as hydrogen bonding.Local Fields at electrolyte-electrode interfaces: Despite decades of work on the electric field variation near a biased electrode, the details of such fields and their influence on chemistry remain elusive. Our goal is not only to measure such fields using vibrational Stark reporters, but also to correlate them with chemical equilibria at the interface. A main hypothesis of our work is that even prior to reaching the electron transfer threshold the polarization induced by the interfacial fields change the local chemical equilibria. We propose direct spectroscopic measurements at subthreshold potentials to measure the consequences of such polarizing fields on chemical equilibria.Local Fields at ionic liquid (IL) interfaces: A challenge in practical applications of ILs is understanding their structure and dynamics at interfaces. We will use VSFG Stark shift spectroscopy to measure the field variations at electrode-IL interfaces.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 09, 2018
- Source ID
- FA95501810021
Entities
People
- Jahan M Dawlaty
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Southern California