The kinetics of biacetyl phosphorescence sensitized in 2875 Å-irradiated SO2–biacetyl–added gas (CO2, CO, N2) mixtures. The nature of the SO2 excited states formed at high added gas pressures
✍ Scribed by Abraham Horowitz; Jack G. Calvert
- Publisher
- John Wiley and Sons
- Year
- 1973
- Tongue
- English
- Weight
- 853 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0538-8066
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✦ Synopsis
The quantum yields of sensitized biacetyl phosphorescence emission have been determined for S02-Fiacetyl-C02, SOZ-biacetyl-Nz, and SO*-biacetyl-CO mixtures irradiated at 2875 A Series of experiments were made at various SO*, biacetyl, and added-gas concentrations (up to 4 X The kinetic data show an "excess" biacetyl emission which requires the participation of some undefined excited state or isomer of SO2 in addition to the emitting singlet ('SOZ) and triplet (?SOZ) states of SO$. These results confirm the experimental observations of Cehelnik et al. 1121 and Wampler et al. [9] who reported that an "excess" quantum yield of COz occurred in 3130 . &irradiated SOZ-CO mixtures at high CO pressures. The kinetic analysis of the data is most consistent with the hypothesis of Wampler et al.; the nonreactive, undefined excited state or high-energy isomer of SOZ, designated here as X, is formed in part as ' S O z is quenched: 'SO, + M -+ (SO%-M) (1); 'SO2 + M -+ + M (2); 'SO2 + M -+ X + M (3).
It decays largely by a nonradiative first-order process at low pressures, X -+ SO2 ( 5) , but it generates %OZ by collisional perturbation at high pressures, X + M -+ %02 + M (4). In terms of this mechanism, the following rate constant ratios are derived from the present study: k t / ( k , + kp + k3) = 0.14 & 0.02 (M = COZ), 0.085 f 0.012 (CO), 0.11 f 0.02 (Nt); and ka/kc (mole/l.) = 0.020 f 0.004 (M = COZ), 0.016 =k 0.003 (CO), 0.021 i 0.005 (NJ.
M ) .
X itself does not transfer energy to biacetyl. kz + k3) = 0.020 f 0.010 (M = COz), 0.021 f 0.010 (Nz), 0.019 zt 0.010 (CO); k s / ( k l +