Rate constant and products of the reaction of O(3P) atoms with thiirane over the temperature range 220-950 K

A discharge-flow modulated molecular beam mass spectrometry technique has been used to determine the rate constant for the reaction of ground state oxygen atoms with C2H4S in the temperature range 220-950 K. The reaction rate constant has been determined directly by monitoring C2H4S in an excess of O atoms and through competitive reaction of oxygen atoms with C2H4S and Br-2. Weak, negative temperature dependence is observed below 300 K, whereas positive temperature dependence is observed above 380 K: k = 1.13 x 10(-12) (T/298)(2.18) exp(733/T) cm(3) molecule(-1) s(-1). We estimate this expression to be accurate within 15% over the investigated temperature range. SO and C2H4 have been detected as reaction products and a branching ratio of unity (with uncertainty of 10%) has been found for the channel forming these two species in the temperature range 300-900 K, confirming that the title reaction is an efficient source of SO radicals.