UV DYNAMICS OF CIS-STILBENE STUDIED BY ULTRAFAST ELECTRON DIFFRACTION

Saha, S. K.

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https://hdl.handle.net/2142/122373 Copy

Description

Title

UV DYNAMICS OF CIS-STILBENE STUDIED BY ULTRAFAST ELECTRON DIFFRACTION

Author(s)

Saha, S. K.

Contributor(s)

• Lin, Ming-Fu
• Centurion, Martin
• Martinez, Todd
• Jobe, Keith
• Yang, Jie
• Wolf, Thomas JA
• Pathak, Shashank
• Ware, Matthew R
• Ji, Fuhao
• Hoffmann, Matthias
• Luo, Duan
• Moore, Bryan
• Attar, Andrew
• Williams, Monika
• Weir, Hayley
• Nunes, Pedr

Issue Date

2023-06-22

Keyword(s)

Photodissociation and photochemistry

Abstract

Stilbene is a prototype molecule for studying photoisomerization and photocyclization mechanisms which are pivotal to converting light into chemical and mechanical energy in nature. Despite multiple decades of research, the exact details of the photoisomerization of cis-stilbene into trans-stilbene and/or its cyclization into 4a,4b-dihydrophenanthrene (DHP) have remained a topic of debate. We have used mega-electronvolt ultrafast electron diffraction (UED) to capture and spatially resolve the photoexcitation dynamics with sub-angstrom resolution. At the SLAC MeV-UED beamline, cis-stilbene was optically pumped with 267 nm ultraviolet light with different pulse energy and probed with 3.7 MeV electrons. We compare our experimental difference-diffraction signals with Ab initio multiple spawning simulations (AIMS) for single-photon excitation dynamics and molecular dynamics simulation for two-photon excitation leading to ionization. We found that with 80uJ pulse energy, the single and two-photon excitation channels are comparable, while with 130uJ pulse energy the two-photon channel dominates. Our data and simulations revealed very different dynamics and end products in the one-photon and two-photon channels.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

Handle URL

https://hdl.handle.net/2142/122373

DOI

https://doi.org/10.15278/isms.2023.6924

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