Prof. Scott Cushing
Physical Chemistry Seminar
Department of Chemistry and Chemical Engineering
California Institute of Technology
Description
Title: From Batteries to Photoelectrochemistry: Exploring Ultrafast Phenomena with Electrons, X-rays, and Entangled Photons
Abstract: The Cushing lab focuses on ultrafast instrumentation building that ranges from tabletop X-rays, entangled photon spectroscopy, ultrafast TEM/EELS, to new forms of battery spectroscopy. In this talk, I will give a brief introduction to our research areas, mentioning the increasingly “null” space explored with entangled photons, and then focus on two of the techniques – table top X-ray spectroscopy and our newly created laser-driven ultrafast impedance method. First, we use transient X-ray techniques to element-specifically explore complex photodynamics in solar to fuel and other solid-state systems. The ultrafast X-ray pulses measure a mix of electronic and structural dynamics, and using our excited state Bethe-Salpeter equation approach, we can extract everything from time-resolved electron and hole energies, defect state occupations, phonon and polaron modes, and transport in multi-layer junctions. New examples include measuring a lattice’s coherent response to polaron formation and dynamic localization in superatomic crystals. Second, we use our newly developed, laser-driven ultrafast impedance method to investigate the ion hopping Hamiltonian of superionic conductors. Picosecond temporal and spectral correlations differentiate electron-ion, electron-phonon, and even potentially ion-ion interactions. Follow up transient XUV studies can then give an atomistic view of how material parameters control solid-state electrolyte and electrode performance.