Photophysical processes in the vapour-phase measured by the optic-acoustic effect. Part 3.—Radiationless processes from the lowest singlet and triplet states of [1H6]benzene and [2H6]benzene
- 1 January 1974
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 70, 1028-1039
- https://doi.org/10.1039/f29747001028
Abstract
Optic-acoustic measurements on the triplet state relaxation of [1H6] benzene and [2H6] benzene are described. The respective triplet deactivation rates in s–1 are 1.7 × 103+ 6.6 × 107[C6H6] and 1.9 × 103+ 2.1 × 107[C6D6] with [C6H6][C6D6] in mol dm–3. The concentration dependent term is discussed in terms of triplet excimer formation which may facilitate the passage through an isomeric intermediate to ground state benzene. For excitation at 40400 cm–1 the triplet quantum yield tends to zero at zero pressure. An explanation of this is given, not involving reversible radiationless processes, but in terms of both pressure-dependent and pressure-independent internal conversion rates out of the vibrationally excited singlet state. With this model internal conversion rates in s–1 are 1.7 × 107+ 1.5 × 1010[C6H6] and 1.3 × 107+ 1.3 × 1010[C6D6] for excitation at 40400 cm–1.Keywords
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