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Mapping the complete reaction path of a complex photochemical reaction

Mapping the complete reaction path of a complex photochemical reaction
Mapping the complete reaction path of a complex photochemical reaction
We probe the dynamics of dissociating CS2 molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield. We explain this by consideration of accurate potential energy curves for both the singlet and triplet states. We propose that rapid internal conversion stabilises the singlet population dynamically, allowing for singlet-triplet relaxation via intersystem crossing and efficient formation of spin-forbidden dissociation products on longer timescales. The study demonstrates the importance of measuring the full reaction pathway for defining accurate reaction mechanisms.
1079-7114
Smith, Adam D.
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Warne, Emily M.
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Bellshaw, Darren
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Horke, Daniel
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Tudorovskya, Maria
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Springate, Emma
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Jones, Alfred
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Cacho, Cephise
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Chapman, Richard T.
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Kirrander, Adam
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Minns, Russell S.
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Smith, Adam D.
af4cf6b6-1d87-47e7-a6f6-c8cc0ea20af8
Warne, Emily M.
63799bdf-67fa-4dd8-adac-b963a9587a28
Bellshaw, Darren
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Horke, Daniel
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Tudorovskya, Maria
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Springate, Emma
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Jones, Alfred
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Cacho, Cephise
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Chapman, Richard T.
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Kirrander, Adam
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Minns, Russell S.
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Smith, Adam D., Warne, Emily M., Bellshaw, Darren, Horke, Daniel, Tudorovskya, Maria, Springate, Emma, Jones, Alfred, Cacho, Cephise, Chapman, Richard T., Kirrander, Adam and Minns, Russell S. (2018) Mapping the complete reaction path of a complex photochemical reaction. Physical Review Letters, 120 (18), [183003]. (doi:10.1103/PhysRevLett.120.183003).

Record type: Article

Abstract

We probe the dynamics of dissociating CS2 molecules across the entire reaction pathway upon excitation. Photoelectron spectroscopy measurements using laboratory-generated femtosecond extreme ultraviolet pulses monitor the competing dissociation, internal conversion, and intersystem crossing dynamics. Dissociation occurs either in the initially excited singlet manifold or, via intersystem crossing, in the triplet manifold. Both product channels are monitored and show that despite being more rapid, the singlet dissociation is the minor product and that triplet state products dominate the final yield. We explain this by consideration of accurate potential energy curves for both the singlet and triplet states. We propose that rapid internal conversion stabilises the singlet population dynamically, allowing for singlet-triplet relaxation via intersystem crossing and efficient formation of spin-forbidden dissociation products on longer timescales. The study demonstrates the importance of measuring the full reaction pathway for defining accurate reaction mechanisms.

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Accepted/In Press date: 23 March 2018
e-pub ahead of print date: 4 May 2018
Published date: 4 May 2018

Identifiers

Local EPrints ID: 419220
URI: http://eprints.soton.ac.uk/id/eprint/419220
ISSN: 1079-7114
PURE UUID: a3dae671-6137-4060-91b7-318af6e4f915
ORCID for Russell S. Minns: ORCID iD orcid.org/0000-0001-6775-2977

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Date deposited: 09 Apr 2018 16:30
Last modified: 15 Sep 2021 05:20

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Contributors

Author: Adam D. Smith
Author: Emily M. Warne
Author: Darren Bellshaw
Author: Daniel Horke
Author: Maria Tudorovskya
Author: Emma Springate
Author: Alfred Jones
Author: Cephise Cacho
Author: Richard T. Chapman
Author: Adam Kirrander

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