Instrument Development: Creating a Tunable, Broad bandwidth 2D IR Microscope for Quantitative Imaging of Chemical Dynamics Near Reactive Surfaces

With the support of the Chemical Measurement and Imaging (CMI) Program in the Division of Chemistry, Amber Krummel of Colorado State University will study the structures and motions of molecules near electrode surfaces. A major goal is to produce molecular snapshots during the formation and growth of the solid electrolyte interphase (SEI) in a model electrochemical cell.

The electrolytes and electrodes used in this project will be chosen to closely model organic battery electrolytes and half-cells contributing to emerging energy storage technologies. Dr. Krummel and her group will be building new capabilities into an emerging imaging technique— 2-dimensional infrared (2D-IR) microscopy. 2D-IR microscopy holds the promise of visualizing the "molecular dance" taking place near electrode surfaces, due to its ability to provide chemical information at ultrafast time scales and its sensitivity to different types of molecular structures.

The efforts supported by this funding will produce new chemical imaging tools crucial to many disciplines of science and technology, such as electrochemical processes associated with clean energy technologies, materials science, biotechnology, and geology. The results of the imaging experiments are expected to provide insights into the fundamental characteristics of SEI, which is key for understanding device performance issues encountered in energy storage technologies.

Further broadening impacts of the project are Dr. Krummel is helping to train the next generation of spectroscopists and microscopists in the areas of physical chemistry, laser physics, and materials chemistry. The primary goal of building a tunable, broad bandwidth 2D-IR microscope will require integration of knowledge in optical physics, imaging, and ultrafast nonlinear optical spectroscopy tools.

Finally, through hands-on mentoring, the researchers in the Krummel group will learn the art of communicating their innovations to broad audiences and principles of community through direct training in diversity, equity, inclusion, and social justice issues within their communities.

Developing an imaging modality capable of reporting chemical dynamics at ultrashort timescales and then connecting the observed dynamics to macroscopic observables is extremely attractive. Two-dimensional infrared (2D-IR) spectroscopy is a proven tool for capturing information on chemical structures and dynamics at femtosecond timescales and longer, which limits its recording chemical information about reactions that are extremely fast and key to many crucial chemical processes.

This project is expected to significantly reduce the acquisition time of 2D IR spectra, thus making it possible to develop new 2D-IR imaging tools to directly measure molecular interactions across multiple length scales. The scientific inquiry outlined in this project aims to create a new nonlinear optical microscopy tool capable of mapping chemical interactions.

The chemical interactions that will be mapped are expected to contain quantitative details of dynamic behaviors in electrolytes near electrode surfaces. The research team will initiate in situ imaging of molecular structures and dynamics during solid electrolyte interphase formation for the first time. These experimentshave to potential to increase knowledge of fundamental driving forces present during SEI formation at electrode surfaces, providing crucial control parameters of the SEI, as well as demonstrating the utility of 2D-IR imaging across a range of scientific disciplines.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.