The SO2-sensitized phosphorescence of biacetyl vapor in photolyses at 2650 and 2875 Å. The intersystem crossing ratio in sulfur dioxide

✍ Scribed by Abraham Horowitz; Jack G. Calvert

• Publisher: John Wiley and Sons
• Year: 1972
• Tongue: English
• Weight: 695 KB
• Volume: 4
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550040206

✦ Synopsis

Quantum yields of the triplet sulfur dioxide (3S02)-sensitized phosphoresence (aBen8) in biacetyl (Ac?) have been determined in experiments over a wide range of przssures of SO0z and ACZ. Excited singlet sulfur dioxide ('SO?) was generated using 2650-A and 2875-A light. The values of asens were dependent on the [SO~]/[ACZ] ratio, as anticpated theoretically. However, in runs at a fixed [SOz]/[Ac?] ratio, the measured 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: 'SO2 + SO, + O(2SO2) (I), 'SO, + SO2 + 3S02 + SO? @), kz/(kl + k2) = 0.082 _+ 0.003 (2650 A), 0.095 f 0.005 (2875 A); 3S02 + Acz --+ S p z f 3 A ~2 (9a), 3 S 0 2 + Ac2 --f SOs + ,Ac? (9b), k g , + k g b = (8.4 & 2.1) X 1O'O (2650 A), (8.1 k 3.0)X10'0 l./mole-sec (2875 A); 3 S 0 2 -SO? + h v , ( 6 ) , ke = (7.3 +_ 1.3)XIO' sec-'.