Rate constants, 1100 ≤ T ≤ 2000 K, for H+NO2→OH+NO using two shock tube techniques:: Comparison of theory to experiment
Rate constants, 1100 ≤ T ≤ 2000 K, for H+NO2→OH+NO using two shock tube techniques:: Comparison of theory to experiment
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DOI：
10.1021/jp0141023
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发表时间：
2002-09-12
影响因子：
2.9
通讯作者：
Fang, DC
中科院分区：
文献类型：
--
作者：
Su, MC;Kumaran, SS;Fang, DC
在反射冲击波实验中，使用两种不同的分析方法在 1100-2000 K 的温度范围内测量了 H + NO2 --> OH + NO 反应的速率常数。在这两种方法中，H原子的来源均来自乙基自由基分解，其中自由基基本上由C2H5I的热分解瞬间形成。第一种方法使用原子共振吸收。光谱测定 (ARAS) 来追踪氢原子的时间行为。实验在[C2H5I](0) 如此低的条件下进行，标题反应可以被化学分离，并且H原子的衰变严格是一级的。这些实验的结果可概括为 k = (1.4+/-0.3) x 10(-10) cm(3) molecular(-1) s(-1)，1100 小于或等于 T 小于或等于 1650 K。第二种方法利用多通道光学系统来观察产物自由基 OH。使用共振灯作为吸收源。由于这是该实验室首次进行 OH 自由基动力学研究，因此需要进行广泛的校准。该过程产生了生长曲线的修正比尔定律描述，随后可用于将吸收数据转换为 OH 自由基分布。该方法的速率常数需要化学模拟，最终结果可概括为 k = (1.8+/-0.2) x 10(-10) cm(3) molecular(-1) s(-1)，1250 小于或等于 T 小于或等于 2000 K。由于两种方法的结果在统计上重叠，因此可以将它们合并，得到 k = (1.64+/-0.30) x 10(-10) cm(3) 分子(-1) s(-1) 为 1100 小于或等于 T 小于或等于 2000 2000 K。当前结果与早期在较低温度下的工作进行比较，组合数据库得出大范围 195-2000 K 的温度依赖性。组合结果可总结为：ask = (1.47+/-0.26) x 10(-10) cm(3) 分子(-1) s(-1) 为 195 小于或等于 T 小于或等于 2000 K。随后使用从头开始电子结构计算结合现代动力学理论从理论上考虑该反应，以合理化热速率行为。
Rate constants for the reaction H + NO2 --> OH + NO have been measured over the temperature range 1100-2000 K in reflected shock wave experiments using two different methods of analysis. In both methods, the source of H-atoms is from ethyl radical decomposition in which the radicals are formed essentially instantaneously from the thermal decomposition of C2H5I. The first method uses atomic resonance absorption. spectrometry (ARAS) to follow the temporal behavior of H-atoms. Experiments were performed under such low [C2H5I](0) that the title reaction could be chemically isolated, and the decay of H-atoms was strictly first-order. The results from these experiments can be summarized as k = (1.4+/-0.3) x 10(-10) cm(3) molecule(-1) s(-1) for 1100 less than or equal to T less than or equal to 1650 K. The second method utilizes a multipass optical system for observing the product radical, OH. A resonance lamp was used as the absorption source. Because this is the first OH-radical kinetics investigation from this laboratory, extensive calibration was required. This procedure resulted in a modified Beer's law description of the curve-of-growth, which could subsequently be used to convert absorption data to OH-radical profiles. Rate constants by this method required chemical simulation, and the final result can be summarized as k = (1.8+/-0.2) x 10(-10) cm(3) molecule(-1) s(-1) for 1250 less than or equal to T less than or equal to 2000 K. Because the results from the two methods statistically overlap, they can be combined giving k = (1.64+/-0.30) x 10(-10) cm(3) molecule(-1) s(-1) for 1100 less than or equal to T less than or equal to 2000 2000 K. The present results are compared to earlier work at lower temperatures, and the combined database yields the temperature dependence over the large range, 195-2000 K. The combined results can be summarized ask = (1.47+/-0.26) x 10(-10) cm(3) molecule(-1) s(-1) for 195 less than or equal to T less than or equal to 2000 K. The reaction is subsequently considered theoretically using ab initio electronic structure calculations combined with modern dynamical theory to rationalize the thermal rate behavior.