A study of the reaction between NaHCO3 and H : Apparent closure on the chemistry of mesospheric Na
A study of the reaction between NaHCO3 and H : Apparent closure on the chemistry of mesospheric Na
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DOI：
10.1029/2000jd900579
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发表时间：
2001-01
影响因子：
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通讯作者：
R. M. Cox;Daniel E. Self;J. Plane
中科院分区：
文献类型：
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作者：
R. M. Cox;Daniel E. Self;J. Plane
碳酸氢钠（NaHCO3）和氢原子H之间的反应是唯一可能的途径（除了可能的白天光解作用），将这个主要的钠库再循环回中层上层的Na原子。在已知的过量H条件下，NaHCO3在快速流动管中反应，得到k(227 k) =（1.7±0.6）× 10−13,k(307 k) =（5.2±2.5）× 10−13 cm3分子−1 s−1，首次确定了速率系数。通过对反应势能面上鞍点的从头算量子计算，过渡态理论很好地描述了这些测量结果。速率系数的温度依赖性为：k(100-400 k) = 1.84 × 10−13 T0.78exp−(1014+130−96/T) cm3分子−1 s−1。当k(T)外推到180-220 k时，与夜间Na层大气模式预测的值非常吻合。因此，这一测量在一级上证明了80公里以上的Na层底部控制中性化学的封闭性。
The reaction between sodium bicarbonate (NaHCO3) and atomic H is the only likely route (apart possibly from daytime photolysis) for recycling this major sodium reservoir back to atomic Na in the upper mesosphere. The rate coefficient was determined for the first time by reacting NaHCO3 in a known excess of H in a fast flow tube, yielding k(227 K) = (1.7 ± 0.6) × 10−13 and k(307 K) = (5.2 ± 2.5) × 10−13 cm3 molecule−1 s−1. These measurements are very well described by transition state theory, using ab initio quantum calculations of the saddle points on the reaction potential energy surface. The resulting temperature dependence of the rate coefficient is then given by k(100–400 K) = 1.84 × 10−13 T0.78exp −(1014+130−96/T) cm3 molecule−1 s−1. When k(T) is extrapolated to 180–220 K, there is excellent agreement with the value predicted from atmospheric models of the nighttime Na layer. Hence this measurement has, to a first order, demonstrated closure of the neutral chemistry governing the underside of the Na layer above 80 km.