The effect of vibrational excitation on the reaction of O(3P) with H2 and the distribution of vibrational energy in the product OH

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Abstract
The overall rate constant and the product branching rate constants have been measured for the first time for the reaction where k2=k2a+k2b. The measurements were made in a flow tube apparatus at T=302±2 °K at a total pressure of 3 Torr. O(3P) was produced by the titration of active nitrogen with NO. H2(v=1) was produced by a heated tungsten filament and its concentration was determined from vuv absorption measurements in the Lyman band system of H2. Absolute concentrations of OH(v=0) and OH(v=1) were deduced from laser induced fluorescence in OH in a calibrated fluorescence system. The rates and uncertainties are k2= (1.0+0.9−0.6) ×10−14 cc/molecule‐sec, k2a= (1.0+0.4−0.6) ×10−14 cc/molecule‐sec, k2b?4.7×10−15 cc/molecule‐sec. The reported value for k2 represents an increase owing to vibrational excitation in hydrogen by a factor of ?2.6×103 over the fully ground state reaction rate constant. Measurements of the fully ground state reaction rate constant and recent theoretical treatments of the O+H2 reaction are discussed in relation to these results.

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