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The SO 2 ‐sensitized phosphorescence of biacetyl vapor in photolyses at 2650 and 2875 Å. The intersystem crossing ratio in sulfur dioxide
Author(s) -
Horowitz Abraham,
Calvert Jack G.
Publication year - 1972
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550040206
Subject(s) - chemistry , intersystem crossing , sulfur dioxide , quantum yield , phosphorescence , singlet state , sulfur , triplet state , excited state , photochemistry , yield (engineering) , analytical chemistry (journal) , fluorescence , atomic physics , inorganic chemistry , organic chemistry , molecule , thermodynamics , physics , quantum mechanics
Quantum yields of the triplet sulfur dioxide ( 3 SO 2 )‐sensitized phosphoresence (Φ sens ) in biacetyl (Ac 2 ) have been determined in experiments over a wide range of pressures of SO 2 and Ac 2 . Excited singlet sulfur dioxide ( 1 SO 2 ) was generated using 2650‐Å and 28757hyphen;Å light. The values of Φ sens were dependent on the [SO 2 ]/[Ac 2 ] ratio, as anticpated theoretically. However, in runs at a fixed [SO 2 ]/[Ac 2 ] ratio, the measured Φ sens values were dependent on the total pressure. This theoretically unexpected effect is probably largely the result of biacetyl triplet diffusion with deactivation at the cell wall. Treatment of the quantum yield data in terms of the complete mechanism gave new estimates of the following rate functions: 1 SO 2 + SO 2 → (2SO 2 ) (1), 1 SO 2 + SO 2 → 3 SO 2 + SO 2 (2), k 2 /( k 1 + k 2 ) = 0.082 ± 0.003 (2650 Å), 0.095 ± 0.005 (2875 Å) 3 SO 2 + Ac 2 → SO 2 + 3 Ac 2 (9a), 3 SO 2 + Ac 2 → SO 2 + Ac 2 (9b), k 9a + k 9b = (8.4 ± 2.1) × 10 10 (2650 Å), (8.1 ± 3.0) × 10 10 l./mole‐sec (2875 Å) 3 SO 2 → SO 2 + hv p (6), k 6 = (7.3 ± 1.3) × 10 1 sec −1 .