Visualizing conical intersection passages via vibronic coherence maps generated by stimulated ultrafast X-ray Raman signals
- 14 September 2020
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 117 (39), 24069-24075
- https://doi.org/10.1073/pnas.2015988117
Abstract
The rates and outcomes of virtually all photophysical and photochemical processes are determined by conical intersections. These are regions of degeneracy between electronic states on the nuclear landscape of molecules where electrons and nuclei evolve on comparable timescales and thus become strongly coupled, enabling radiationless relaxation channels upon optical excitation. Due to their ultrafast nature and vast complexity, monitoring conical intersections experimentally is an open challenge. We present a simulation study on the ultrafast photorelaxation of uracil, based on a quantum description of the nuclei. We demonstrate an additional window into conical intersections obtained by recording the transient wavepacket coherence during this passage with an X-ray free-electron laser pulse. Two major findings are reported. First, we find that the vibronic coherence at the conical intersection lives for several hundred femtoseconds and can be measured during this entire time. Second, the time-dependent energy-splitting landscape of the participating vibrational and electronic states is directly extracted from Wigner spectrograms of the signal. These offer a physical picture of the quantum conical intersection pathways through visualizing their transient vibronic coherence distributions. The path of a nuclear wavepacket in the vicinity of the conical intersection is directly mapped by the proposed experiment.Funding Information
- U.S. Department of Energy (DE-FG02-04ER15571)
- National Science Foundation (CHE-1953045)
- Alexander von Humboldt-Stiftung (Feodor Lynen program)
This publication has 36 references indexed in Scilit:
- Ultrafast Relaxation Dynamics of Uracil Probed via Strong Field Dissociative IonizationThe Journal of Physical Chemistry A, 2013
- Optimal control theory – closing the gap between theory and experimentPhysical Chemistry Chemical Physics, 2012
- Conical intersection dynamics of the primary photoisomerization event in visionNature, 2010
- Ultrafast Nonlinear Optical Signals Viewed from the Molecule’s PerspectivePublished by Elsevier BV ,2010
- Efficient Deactivation of a Model Base Pair via Excited-State Hydrogen TransferScience, 2004
- Diabolical conical intersectionsReviews of Modern Physics, 1996
- Linear and nonlinear response functions for an exact state and for an MCSCF stateThe Journal of Chemical Physics, 1985
- An accurate and efficient scheme for propagating the time dependent Schrödinger equationThe Journal of Chemical Physics, 1984
- Efficient diffuse function‐augmented basis sets for anion calculations. III. The 3‐21+G basis set for first‐row elements, Li–FJournal of Computational Chemistry, 1983
- Molecular dynamics and spectra. I. Diatomic rotation and vibrationThe Journal of Chemical Physics, 1981