Imaging conical intersection dynamics during azobenzene photoisomerization by ultrafast X-ray diffraction
- 12 January 2021
- 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. 118 (3)
- https://doi.org/10.1073/pnas.2022037118
Abstract
X-ray diffraction is routinely used for structure determination of stationary molecular samples. Modern X-ray photon sources, e.g., from free-electron lasers, enable us to add temporal resolution to these scattering events, thereby providing a movie of atomic motions. We simulate and decipher the various contributions to the X-ray diffraction pattern for the femtosecond isomerization of azobenzene, a textbook photochemical process. A wealth of information is encoded besides real-time monitoring of the molecular charge density for the cis to trans isomerization. In particular, vibronic coherences emerge at the conical intersection, contributing to the total diffraction signal by mixed elastic and inelastic photon scattering. They cause distinct phase modulations in momentum space, which directly reflect the real-space phase modulation of the electronic transition density during the nonadiabatic passage. To overcome the masking by the intense elastic scattering contributions from the electronic populations in the total diffraction signal, we discuss how this information can be retrieved, e.g., by employing very hard X-rays to record large scattering momentum transfers.Keywords
Funding Information
- U.S. Department of Energy (DE-SC0019484)
- Alexander von Humboldt-Stiftung (Feodor Lynen program)
This publication has 57 references indexed in Scilit:
- Imaging electronic quantum motion with lightProceedings of the National Academy of Sciences of the United States of America, 2012
- Femtosecond nanocrystallography using X-ray lasers for membrane protein structure determinationCurrent Opinion in Structural Biology, 2011
- Femtosecond X-ray protein nanocrystallographyNature, 2011
- Mechanism and Dynamics of Azobenzene PhotoisomerizationJournal of the American Chemical Society, 2003
- Femtosecond/Picosecond Time-Resolved Spectroscopy of trans- Azobenzene: Isomerization Mechanism Following S2(ππ*) ← S0PhotoexcitationBulletin of the Chemical Society of Japan, 2002
- Reconstruction of the Shapes of Gold Nanocrystals Using Coherent X-Ray DiffractionPhysical Review Letters, 2001
- Ultrafast X-ray Diffraction TheoryThe Journal of Physical Chemistry A, 1998
- Diabolical conical intersectionsReviews of Modern Physics, 1996
- Density matrix averaged atomic natural orbital (ANO) basis sets for correlated molecular wave functionsTheoretical Chemistry Accounts, 1990
- Molecular dynamics and spectra. I. Diatomic rotation and vibrationThe Journal of Chemical Physics, 1981