Quenching rate constants for the removal of SO2(3B1) by various fluorinated olefins

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Abstract
A competitive technique employing the SO2(3B1) photosensitized isomerization of cis‐C2F2H2 to trans‐C2F2H2 in the presence of selected fluorinated olefins has been used at 3712 Å and 22°C to determine the quenching rate constants of the reaction \documentclass{article}\pagestyle{empty}${\rm SO}_{\rm 2} ({}^3B_1){\rm M}\mathop \to \limits^{k_{_4}}$ removal. With PSo2 = 25.4 torr and Pcis‐C2F2H2 = 0.239 torr Stern–Volmer plots for M = C2H4, C2H2F, 1,1‐C2F2H2, C2F4, and C3F6 yielded k4 (units of 1010 l./mole · sec) values of 5.29 ± 0.16, 4.21 ± 0.53, 1.92 ± 0.23, 0.575 ± 0.060, and 0.0335 ± 0.0027, respectively. The results were consistent with the ability of an olefin to quench SO2(3B1) being inversely proportional to the polarizability of the olefin's π bond and the effect can be clearly noted as each H atom in C2H4 is individually replaced by an F atom.