Chemical Sciences and Engineering Division, Argonne National Laboratory , Argonne, Illinois 60439, United States.
J Phys Chem A. 2013 Sep 19;117(37):9011-22. doi: 10.1021/jp4068069. Epub 2013 Sep 9.
The NH2 + NO2 reaction has been studied experimentally and theoretically. On the basis of laser photolysis/LIF experiments, the total rate constant was determined over the temperature range 295-625 K as k1,exp(T) = 9.5 × 10(-7)(T/K)(-2.05) exp(-404 K/T) cm(3) molecule(-1) s(-1). This value is in the upper range of data reported for this temperature range. The reactions on the NH2 + NO2 potential energy surface were studied using high level ab initio transition state theory (TST) based master equation methods, yielding a rate constant of k1,theory(T) = 7.5 × 10(-12)(T/K)(-0.172) exp(687 K/T) cm(3) molecule(-1) s(-1), in good agreement with the experimental value in the overlapping temperature range. The two entrance channel adducts H2NNO2 and H2NONO lead to formation of N2O + H2O (R1a) and H2NO + NO (R1b), respectively. The pathways through H2NNO2 and H2NONO are essentially unconnected, even though roaming may facilitate a small flux between the adducts. High- and low-pressure limit rate coefficients for the various product channels of NH2 + NO2 are determined from the ab initio TST-based master equation calculations for the temperature range 300-2000 K. The theoretical predictions are in good agreement with the measured overall rate constant but tend to overestimate the branching ratio defined as β = k1a/(k1a + k1b) at lower temperatures. Modest adjustments of the attractive potentials for the reaction yield values of k1a = 4.3 × 10(-6)(T/K)(-2.191) exp(-229 K/T) cm(3) molecule(-1) s(-1) and k1b = 1.5 × 10(-12)(T/K)(0.032) exp(761 K/T) cm(3) molecule(-1) s(-1), in good agreement with experiment, and we recommend these rate coefficients for use in modeling.
NH2 + NO2 反应已通过实验和理论进行了研究。基于激光光解/LIF 实验，在 295-625 K 的温度范围内确定了总速率常数 k1,exp(T) = 9.5×10(-7)(T/K)(-2.05) exp(-404 K/T) cm(3) molecule(-1) s(-1)。该值处于该温度范围内报道的数据的较高范围内。使用高精度从头算过渡态理论 (TST) 基于主方程方法研究了 NH2 + NO2 势能面上的反应，得出速率常数 k1,theory(T) = 7.5×10(-12)(T/K)(-0.172) exp(687 K/T) cm(3) molecule(-1) s(-1)，与重叠温度范围内的实验值非常吻合。两个入口通道加合物 H2NNO2 和 H2NONO 分别导致 N2O + H2O (R1a) 和 H2NO + NO (R1b) 的形成。尽管漫游可能促进加合物之间的少量通量，但通过 H2NNO2 和 H2NONO 的途径基本上是不相关的。通过从头算 TST 基于主方程的计算，确定了 NH2 + NO2 的各种产物通道的高低压极限速率系数，温度范围为 300-2000 K。理论预测与测量的总速率常数非常吻合，但在较低温度下倾向于高估定义为β=k1a/(k1a+k1b)的分支比。对反应的吸引势进行适度调整，得到 k1a = 4.3×10(-6)(T/K)(-2.191) exp(-229 K/T) cm(3) molecule(-1) s(-1)和 k1b = 1.5×10(-12)(T/K)(0.032) exp(761 K/T) cm(3) molecule(-1) s(-1)的值，与实验结果非常吻合，我们建议在建模中使用这些速率系数。
