Experimental measurement of the rate of the reaction o( 3 P ) + H 2 ( v = 0) → OH( v = 0) + H at T = 298 K

Measurement of the rate of the reactionis reported. The measurements were made in a flow tube apparatus. The result is based on data for the absolute density of OH( v = 0) obtained from laser‐induced fluorescence measurements in the (0–0) band of the OH( A 2 Σ + → X 2 II) system. The density of oxygen atoms was varied by changing the flow rate of NO which is consumed in the reaction N + NO → O + N 2 . We find that k 1 (298 K) = (5.5 ± 3.0) × 10 6 cm 3 /mol sec. This result was obtained with consideration and control of the effect of reaction (2):for which vibrationally excited hydrogen is created by energy transfer in the presence of active nitrogen. It was found that the addition of N 2 or CO 2 effectively suppressed the excitation of H 2 ( v = 1). Measurements of the density of H 2 ( v = 1) were made by VUV absorption in the Lyman band system of H 2 . All of the reports of low‐temperature measurements and some recent theoretical calculations for k 1 are discussed. The present result confirms and extends the growingevidence for significant curvature in the low‐temperature end of a modified Arrhenius plot of k 1 ( T ).