PRESSURE SATURATION OF THE COLLISIONAL QUENCHING OF THE $^{3}B_{1}$ STATE OF $SO_{2}$
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Date
1977
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Ohio State University
Abstract
The lifetime of the $^{3}B_{1}$ state of $SO_{2}$ has been measured using a photon counting technique at gas pressures up to 2 atm. At low pressures inert gases such as $N_{2}$ and $CO_{2}$ quench triplet $SO_{2}$, but at a pressure of about an atmosphere, the quenching saturates and the lifetime is unaffected by further increases in the pressure of these gases. Collisions with ground state $SO_{2}$ molecules also quench the triplet: state at low pressures, but at pressures above 250 Torr this quenching partially saturates. The residual quenching at higher $SO_{2}$ pressures is attributed to the reaction $^{3}SO_{2} + SO_{2} \rightarrow SO_{3} + ^{3}SO$ which was observed by Calvert and $coworkers.^{1}$ The pressure saturation can be interpreted in terms of the theory of collision induced intersystem crossing developed by $Freed.^{2}$ Quenching of triplet $SO_{2}$ by $O_{2}$ is more complicated and does not pressure saturate.
Description
$^{1}$ K. Chung, J. G. Calvert, and J, W. Bottenheim, Int. J. Chem. Kin. 7,161 (1975). $^{2}$ K. F. Freed, J. Chem. Phys. 64, 1604 (1976).
Author Institution: Department of Chemistry, University of Colorado
Author Institution: Department of Chemistry, University of Colorado