Identification of a receiver triplet state in the ultrafast intersystem crossing of carbonylpyrenes

The near-unity triplet quantum yield of photoexcited carbonyl functionalized pyrenes is theoretically investigated. The estimated energetics of singlet-triplet manifolds and relevant spin-orbit coupling parameters strongly suggest triplet state formation via the S 1 → T 4 /T 5 pathway. Quantum wavep...

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Bibliographic Details
Published in:Physical chemistry chemical physics : PCCP 2020-03, Vol.22 (11), p.6145-6153
Main Authors: , Kurup, Gayathri B, Vennapusa, Sivaranjana Reddy
Format: Article
Language:English
Subjects:
Atomic energy levels
Carbonyls
Coupling (molecular)
Internal conversion
Manifolds
Pyrenes
Spin-orbit interactions
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Summary:The near-unity triplet quantum yield of photoexcited carbonyl functionalized pyrenes is theoretically investigated. The estimated energetics of singlet-triplet manifolds and relevant spin-orbit coupling parameters strongly suggest triplet state formation via the S 1 → T 4 /T 5 pathway. Quantum wavepacket dynamics of triplet manifolds within the linear vibronic coupling approach reveal that the receiver triplet state would undergo rapid internal conversion decay to the lower triplet state(s), facilitating efficient triplet generation by minimizing the reverse intersystem crossing possibilities. On the basis of these results, a unified mechanism is proposed to describe the ultrafast intersystem crossing process in these molecules. The intersystem crossing receiver triplet state lifetime dictates the efficiency of the triplet quantum yield in carbonylpyrenes.
ISSN:1463-9076
1463-9084
DOI:10.1039/c9cp06857k