Triplets in the cradle: ultrafast dynamics in a cyclic disulfide

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Main Authors: Merrick, James, Hutton, Lewis, Cooper, Joseph C., Vallance, Claire, Kirrander, Adam
Format: Preprint
Published: 2025
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_version_ 1866912631055450112
author Merrick, James
Hutton, Lewis
Cooper, Joseph C.
Vallance, Claire
Kirrander, Adam
author_facet Merrick, James
Hutton, Lewis
Cooper, Joseph C.
Vallance, Claire
Kirrander, Adam
contents The effect of spin-orbit coupling on the "Newton's cradle"-type photodynamics in the cyclic disulfide 1,2-dithiane (C4H8S2) is investigated theoretically. We consider excitation by a 290 nm laser pulse and simulate the subsequent ultrafast nonadiabatic dynamics by propagating surface-hopping trajectories using SA(4|4)-CASSCF(6,4)-level electronic structure calculations with a modified ANO-R1 basis set. Two simulations are run: one with singlet states only, and one with both singlet and triplet states. All trajectories are propagated for 1 ps with a 0.5 fs timestep. Comparison of the simulations suggests that the presence of triplet states depletes the singlet state population, with the net singlet and triplet populations at long times tending towards their statistical limit. Crucially, the triplet states also hinder the intramolecular thiyl radical recombination pathway via the efficient intersystem crossing between the singlet and triplet state manifolds.
format Preprint
id arxiv_https___arxiv_org_abs_2505_20055
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Triplets in the cradle: ultrafast dynamics in a cyclic disulfide
Merrick, James
Hutton, Lewis
Cooper, Joseph C.
Vallance, Claire
Kirrander, Adam
Chemical Physics
The effect of spin-orbit coupling on the "Newton's cradle"-type photodynamics in the cyclic disulfide 1,2-dithiane (C4H8S2) is investigated theoretically. We consider excitation by a 290 nm laser pulse and simulate the subsequent ultrafast nonadiabatic dynamics by propagating surface-hopping trajectories using SA(4|4)-CASSCF(6,4)-level electronic structure calculations with a modified ANO-R1 basis set. Two simulations are run: one with singlet states only, and one with both singlet and triplet states. All trajectories are propagated for 1 ps with a 0.5 fs timestep. Comparison of the simulations suggests that the presence of triplet states depletes the singlet state population, with the net singlet and triplet populations at long times tending towards their statistical limit. Crucially, the triplet states also hinder the intramolecular thiyl radical recombination pathway via the efficient intersystem crossing between the singlet and triplet state manifolds.
title Triplets in the cradle: ultrafast dynamics in a cyclic disulfide
topic Chemical Physics
url https://arxiv.org/abs/2505.20055