Elucidating Charge, Spin, and Solvation Dynamics at Electrochemical Interfaces

Please join Yale Chemistry for a Silliman Seminar in physical chemistry with Prof. L. Robert Baker, Andrei Baronov and Ratmir Timashev Professor in Chemical Physics, Department of Chemistry and Biochemistry, at Ohio State University. Abstract: Nearly all energy conversion and information processing technologies rely on charge and spin transport in systems that are far from equilibrium. The goal to understand and control these processes motivates the need to develop methods to probe the underlying electron dynamics in functional materials on the relevant scales of time and space. To meet this challenge, we utilize high harmonic generation to produce extreme ultraviolet (XUV) light with femtosecond to attosecond pulse durations. Like X-ray absorption, XUV spectroscopy is element specific, providing chemical details of individual elements in complex materials. To extend this technique to study electron dynamics at surfaces, we have pioneered XUV reflection as a surface sensitive analog of XUV absorption. This method now enables direct observation of interfacial charge and spin transport with surface sensitivity, ultrafast time resolution, and unprecedented chemical specificity. This talk will present recent measurements using linearly and circularly polarized XUV light, which show how spin polarized electron transport increases water splitting efficiency in yttrium iron garnet (Y3Fe5O12) by more than an order of magnitude compared to widely studied hematite (α-Fe2O3) through the formation of spin-locked magnon-polarons and how angular momentum exchange between electrons and chiral phonons generates ultrafast spin polarization in chiral semiconductors. Finally, this talk will describe nonlinear vibrational spectroscopy of interfacial electric fields, which mediate charge transfer kinetics during electrochemical catalysis, and show how together these spectroscopic methods provide a detailed understanding of the molecular features of interfaces that govern non-equilibrium reaction dynamics. Bio: Robert Baker received his B.S. degree from Brigham Young University in 2007 and his Ph.D. from the University of California, Berkeley in 2012 under the supervision of Gabor Somorjai. Following a postdoctoral fellowship with Stephen Leone, he joined The Ohio State University in 2014. His awards include the Camille Dreyfus Teacher-Scholar Award, Coblentz Award in Molecular Spectroscopy, Emerging Leader in Atomic Spectroscopy, Young Innovator Award in NanoEnergy, Journal of Physical Chemistry/PHYS Division Lectureship, DOE Early Career Award, and AFOSR Young Investigator Award. Baker was the John von Neumann Distinguished Fulbright Fellow to Hungary in 2023 where he performed research at the Extreme Light Infrastructure Attosecond Light Pulse Source. He is the founding director of the NSF National eXtreme Ultrafast Science (NeXUS) Facility. His research focuses on developing spectroscopic tools to probe charge, spin, and solvent dynamics at catalytic interfaces. In addition to research, he is enthusiastic about teaching and mentoring the next generation of scientific leaders. For more information on Prof. Baker's research: Research - The Baker Group Hosted by Prof. Eric Arsenault. Sponsored by the Mrs. Hepsa Ely Silliman Memorial Fund.