Stephen R. Leone
An X-ray Revolution in Chemical Dynamics
Tue, Oct. 8, 2024, 4:30pm
Taylor Auditorium, Frick Chemistry Lab B02
Host: Marissa Weichman
Speaker Details:
Professor of Chemistry
Professor of Physics
John R. Thomas Endowed Chair in Physical Chemistry
University of California – Berkeley
Ultrafast X-ray spectroscopic investigations utilize transitions from localized inner shells of specific atomic sites in molecules or solids to valence orbitals or bands, defining new ways to obtain information about chemical dynamics. Observations of the passage through conical intersections reveal the precise timescales of curve crossing dynamics. Coherent vibrational superpositions obtain the slopes of inner shell potentials with bond elongation. In solids, the measurement of rapid carrier relaxation and the excitation of solid-state coherent phonon motion reveal the mechanisms of these dynamics. Jahn-Teller distortion is observed in real time on few-femtosecond timescales as small molecules abruptly change symmetry, with a few periods of ensuing coherent vibrational motion. The role of X-rays in the investigation of novel features in molecular and solid-state coherent dynamics is described.
Kobayashi and S. R. Leone, ” Characterizing coherences in chemical dynamics with attosecond time-resolved X-ray absorption spectroscopy,” J. Chem. Phys. 157, 180901 (2022).
E. Ridente, D. Hait, E. A. Haugen, A. D. Ross, D. M. Neumark, M. Head-Gordon, and S. R. Leone, “Femtosecond symmetry breaking and coherent relaxation of methane cations via X-ray spectroscopy,” Science 380, 713 (2023).
L. Barreau, A. D. Ross, V. Kimberg, P. Krasnov, S. Blinov, D. M. Neumark, and S. R. Leone, “Core-excited states of SF6 probed with soft X-ray femtosecond transient absorption of vibrational wavepackets,” Phys. Rev. A 108, 012805 (2023).
Kobayashi, D. M. Neumark, and S. R. Leone, “Theoretical analysis of the role of complex transition dipole phase in XUV transient-absorption probing of charge migration,” Opt. Express 30, 5673 (2022).