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A PULSE RADIOLYSIS and PULSED LASER STUDY OF THE VITAMIN D3 TRIPLET STATE: LIFETIME, RELAXATION and ‘NONVERTICAL’EXCITATION
Author(s) -
Gorman A. A.,
Hamblett I.,
Lambert C.,
Prescott A. L.
Publication year - 1990
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1990.tb01680.x
Subject(s) - triplet state , chemistry , photochemistry , singlet state , radiolysis , excitation , acceptor , endothermic process , reaction rate constant , benzene , singlet oxygen , molecule , atomic physics , oxygen , radical , excited state , kinetics , physics , organic chemistry , quantum mechanics , condensed matter physics , adsorption
— The triplet state of vitamin D3 in benzene has been characterised in terms of its absorption spectrum, Λ max 315 nm, its lifetime, 300 ns, its rate constant for reaction with oxygen, 4.2 times 10 9 mol −1 s −1 and the efficiency with which it sensitizes the formation of singlet oxygen, 25%. There is a large difference in the electronic excitation energies of the spectroscopic and relaxed triplets, ˜ 237 kJ mol −1 and147–168 kJ mol −1 , respectively. It has been shown that, in the endothermic situation, the vitamin D3 molecule is a 'nonvertical'acceptor of triplet energy. This is in accord with the non‐planar character of its acyclic conjugated Il‐system.