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Singlet O2 from Ultraviolet Excitation of the Quinoline-O2 Complex
Bradley F Parsons1, Marcos R Rivera1, Mark A Freitag1
1Department of Chemistry and Biochemistry, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, United States.
The Journal of Physical Chemistry. A
|June 1, 2023
Summary
Photodissociation of quinoline-O2 complexes yields excited oxygen molecules. Electronic structure calculations and experimental translational energy distributions suggest quinoline is formed in its lowest triplet state via statistical dissociation.
Area of Science:
- Photochemistry
- Chemical Physics
- Quantum Chemistry
Background:
- The study investigates the photodissociation dynamics of the quinoline-O2 complex.
- Understanding excited states and dissociation pathways is crucial in chemical kinetics.
Purpose of the Study:
- To determine the electronic state of quinoline formed after photodissociation of the quinoline-O2 complex.
- To characterize the translational energy distribution of dissociation products.
- To elucidate the dissociation mechanism.
Main Methods:
- Photodissociation of the quinoline-O2 complex using UV light (near 312 nm).
- Detection of excited oxygen (O2 a 1Δg) using resonance enhanced multiphoton ionization and velocity map ion imaging.
- Electronic structure calculations (CCSD/aug-cc-pVDZ//(U)MP2/cc-pVDZ) for ground and triplet states of quinoline and quinoline-O2 complexes.
Main Results:
- The lowest excited state of oxygen, O2 a 1Δg, was identified as a product.
- Electronic structure calculations revealed the lowest triplet state of quinoline has ππ* character, 2.69 eV above the ground state.
- The most stable quinoline-O2 complex has a binding energy of ~0.11 eV.
- Experimental translational energy distributions align with a statistical dissociation model.
Conclusions:
- The quinoline product is predominantly formed in its lowest energy triplet state.
- The dissociation process for the quinoline-O2 complex is likely statistical.
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