Imaging conical intersection dynamics during azobenzene photoisomerization by ultrafast X-ray diffraction

Keefer, Daniel; Aleotti, Flavia; Rouxel, Jérémy R.; Segatta, Francesco; Gu, Bing; Nenov, Artur; Garavelli, Marco; Mukamel, Shaul

doi:10.1073/pnas.2022037118

DOE OSTI · 1759080

Imaging conical intersection dynamics during azobenzene photoisomerization by ultrafast X-ray diffraction

Keefer, Daniel·Aleotti, Flavia·Rouxel, Jérémy R.·Segatta, Francesco·Gu, Bing·Nenov, Artur·Garavelli, Marco·Mukamel, Shaul

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Abstract

Significance Vibronic coherences are unique features that emerge in the decisive moments of photochemistry and photophysics. Here we demonstrate how X-ray diffraction can access fundamental information about these coherences. This is enabled by recent developments at free-electron lasers, working toward temporal resolution and single-molecule accessibility of scattering-based measurements. Time-resolved diffraction patterns of the isomerization of azobenzene are simulated. The process is monitored in time via the momentum-space signal, with a special focus on the mixed elastic/inelastic scattering from coherences. We give practical ideas on how this relatively weak contribution to the signal can potentially be retrieved. A direct connection to the real-space movie of the conical intersection dynamics is made, enabling the observation of quantum coherences that direct chemical processes.

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY Science & Technology - Other Topics X-ray diffraction conical intersections ultrafast dynamics vibronic coherence

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Keefer, Daniel, Aleotti, Flavia, Rouxel, Jérémy R., Segatta, Francesco, Gu, Bing, Nenov, Artur, Garavelli, Marco, Mukamel, Shaul. 2021-01-12. Imaging conical intersection dynamics during azobenzene photoisomerization by ultrafast X-ray diffraction. https://doi.org/10.1073/pnas.2022037118

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