Experimental measurement of the rate of the reaction o(3P) + H2(v = 0) → OH(v = 0) + H at T = 298 K

Measurement of the rate of the reaction is 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(A²Σ⁺ → X²II) system. The density of oxygen atoms was varied by changing the flow rate of NO which is consumed in the reaction N + NO → O + N₂. We find that k₁ (298 K) = (5.5 ± 3.0) × 10⁶ cm³/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 N₂ or CO₂ effectively suppressed the excitation of H₂(v = 1). Measurements of the density of H₂(v = 1) were made by VUV absorption in the Lyman band system of H₂. All of the reports of low-temperature measurements and some recent theoretical calculations for k₁ are discussed. The present result confirms and extends the growingevidence for significant curvature in the low-temperature end of a modified Arrhenius plot of k₁ (T).