| The kinetics of the pressure dependent O + SO2 + Ar reaction have been investigated using laser photolysis resonance fluorescence at temperatures of 289 K, 399 K, 581 K, 699 K, 842 K and 1040 K and at pressures from 30–665 torr. Falloff was observed for the first time in the pressure dependence. Application of Lindemann theory yielded an Arrhenius expression of k(T) = 3.3 × 10−32exp(−992/T) cm6 molecule−1s−1 for the low pressure limit and k(T) = 8.47 × 10−14exp(−468/T) cm3 molecule−1 s−1 for the high pressure limit at temperatures between 289 and 842 K. The reaction is unusual as it possesses a positive activation energy at low temperature, yet at higher temperatures the activation energy is negative, illustrating a reaction barrier. |
