David Blank- University of MN- Twin Cities

https://cse.umn.edu/chem/david-blank
https://blank.chem.umn.edu/

Title: "Investigating the Nature, Dynamics and Reactivity of Excess Electrons in Ionic Liquids"

Abstract: Due to a number of favorable physical properties, ionic liquids have become more common in a wide variety of energy related applications. The applications include solar energy conversion, fuel cells, super capacitors, nuclear fuel separation, and ionic satellite propellants. These applications involve radiolytic environments and include the generation of excess electrons. This has driven increasing interest in the creation, behavior and reactivity of excess electrons in ionic liquids. Unlike molecular species, for example CO2, where the structure of the reactant provides a starting point for understanding reactivity, the structure of an excess electron in an ionic liquid is not established or well understood. This leaves us with some very interesting initial questions. Is the excess electron delocalized over the ions of the liquid, localized on one or more of the ions, in the space between the ions, or some combination of these? The primary experimental tools we have used for investigating excess electrons are time-resolved photo-detachement and pulse radiolysis. This is complemented by world-class molecular simulations right here at the University of Iowa. We will show that together these methods provide an initial picture of the excess electron that is born delocalized but rapidly relaxes (localizes?) in a process that arrests its reactivity on a sub-picosecond timescale. We will also introduce a somewhat unique application of femtosecond stimulated Raman spectroscopy (FSRS), as a potential tool to probe details of the electron’s structure, better understand the dynamics and reactivity, and provide more robust data to test the simulations.