Intersystem crossing in the exit channel
- Univ. of Missouri, Columbia, MO (United States)
- Temple Univ., Philadelphia, PA (United States)
We report that intersystem crossing (ISC), plays an important role in photochemistry. It is understood to be efficient when heavy atoms are present due to strong spin–orbit coupling, or when strongly bound long-lived complexes are formed that increase the chance of finding the singlet–triplet intersection seam. Here we present evidence for a different ISC mechanism in the bimolecular reaction of O(3P) with alkylamines. In crossed-beam experiments, product velocity-flux maps are measured for aminoalkyl radicals produced from H-abstraction from the methyl group, which also gives OH radicals as co-fragments. The low translational-energy release and isotropic angular distributions of the products indicate that such reactions undergo the formation of a complex before OH and aminoalkyl are produced. However, there is no well on the triplet potential-energy-surface that could support such a complex. Multireference ab initio calculations suggest, instead, that ISC occurs in the exit-channel region due to the long-range dipole–dipole interaction between the nascent radical product pair coupled with the vanishing singlet–triplet splitting at long range. Finally, ISC then leads to a deep hydroxylamine well before OH elimination.
- Research Organization:
- Univ. of Missouri, Columbia, MO (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences, and Biosciences Division; ARO; National Science Foundation (NSF)
- Grant/Contract Number:
- SC0017130; W911NF-17-1-0099; CHE-1800171
- OSTI ID:
- 1595258
- Journal Information:
- Nature Chemistry, Vol. 11, Issue 2; ISSN 1755-4330
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
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