David Flannigan, University of Minnesota
When
Where
Abstract: Spatial and energy resolutions of state-of-the-art transmission electron microscopes now exceed 50 pm and 5 meV, beyond the Bohr radius and below 1 THz frequencies. Such advances have been driven by innovation in electron sources and optics, particularly aberration correctors and cold field-emission guns. Now, the final dimensional frontier in electron microscopy – time – is at last being pushed to the corresponding fundamental limits of chemical and materials transformation. Here I will describe how this “Temporal Resolution Revolution” began and how it is growing, with chemists, materials scientists, and physicists together pushing the boundaries to the femtosecond timescale and beyond. I will divide the lecture into roughly two parts: (1) a description of the instrumentation and the approach to performing laser-driven ultrafast electron microscopy (UEM) experiments, and (2) an overview of select examples of using UEM to probe ultrafast nanostructural and nanoscale materials dynamics: e.g., metal nanoparticle dynamics, lattice dynamics of layered materials, and electronic/structural phase transformation dynamics. I will conclude with a brief a forward-looking perspective.
Bio: David Flannigan is currently Professor of Chemical Engineering and Materials Science and Graduate Faculty in Chemical Physics at the University of Minnesota. He obtained a B.S. in Chemistry at the University of Minnesota and a Ph.D. in Chemistry from the University of Illinois at Urbana-Champaign, where he studied sonoluminescence in the labs of Ken Suslick. He then went on to conduct postdoctoral research in the labs of Ahmed Zewail at Caltech, where he worked with a team to develop and apply 4D ultrafast electron microscopy to a broad range of chemical, biological, and materials problems. While at Caltech, he co-invented Photon-Induced Near-Field Electron Microscopy (PINEM), a technique now adopted and used by numerous labs to study electron-photon quantum coherent phenomena. He joined the faculty at the University of Minnesota in 2012, where he has most recently focused on pushing the limits of UEM imaging toward combined angstrom-femtosecond resolutions. His group’s work has been recognized with an NSF CAREER Award, a DOE Young Investigator Award, a Beckman Young Investigator Award, and a Sigma Xi Young Investigator Award. He was elected a Fellow of Sigma Xi in 2023.
3:00 PM in PAS 201 / Zoom Meeting
Refreshments in PAS 236, 2:30PM