Unveiling the spatial distribution of molecular coherences at conical intersections by covariance X-ray diffraction signals.

Autor:	Cavaletto SM; Department of Chemistry, University of California, Irvine, CA 92697.; Department of Physics & Astronomy, University of California, Irvine, CA 92697., Keefer D; Department of Chemistry, University of California, Irvine, CA 92697.; Department of Physics & Astronomy, University of California, Irvine, CA 92697., Rouxel JR; Department of Chemistry, University of California, Irvine, CA 92697.; Department of Physics & Astronomy, University of California, Irvine, CA 92697.; University Lyon, UJM-Saint-Étienne, CNRS, Graduate School Optics Institute, Laboratoire Hubert Curien UMR 5516, Saint-Étienne 42023, France., Aleotti F; Dipartimento di Chimica Industriale, Università degli Studi di Bologna, 40136 Bologna, Italy., Segatta F; Dipartimento di Chimica Industriale, Università degli Studi di Bologna, 40136 Bologna, Italy., Garavelli M; Dipartimento di Chimica Industriale, Università degli Studi di Bologna, 40136 Bologna, Italy., Mukamel S; Department of Chemistry, University of California, Irvine, CA 92697; smukamel@uci.edu.; Department of Physics & Astronomy, University of California, Irvine, CA 92697.
Jazyk:	angličtina
Zdroj:	Proceedings of the National Academy of Sciences of the United States of America [Proc Natl Acad Sci U S A] 2021 Jun 01; Vol. 118 (22).
DOI:	10.1073/pnas.2105046118
Abstrakt:	The outcomes and timescales of molecular nonadiabatic dynamics are decisively impacted by the quantum coherences generated at localized molecular regions. In time-resolved X-ray diffraction imaging, these coherences create distinct signatures via inelastic photon scattering, but they are buried under much stronger background elastic features. Here, we exploit the rich dynamical information encoded in the inelastic patterns, which we reveal by frequency-dispersed covariance ultrafast powder X-ray diffraction of stochastic X-ray free-electron laser pulses. This is demonstrated for the photoisomerization of azobenzene involving the passage through a conical intersection, where the nuclear wave packet branches and explores different quantum pathways. Snapshots of the coherence dynamics are obtained at high frequency shifts, not accessible with conventional diffraction measurements. These provide access to the timing and to the confined spatial distribution of the valence electrons directly involved in the conical intersection passage. This study can be extended to full three-dimensional imaging of conical intersections with ultrafast X-ray and electron diffraction. Competing Interests: Competing interest statement: S.M. and H.J.W. are coauthors on a 2018 roadmap article, L. Young et al., Roadmap of ultrafast X-ray atomic and molecular physics, J. Phys. B At. Mol. Opt. Phys. 51, 032003 (2018).
Databáze:	MEDLINE
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