On the curvature in logarithmic plots of rate coefficients for chemical reactions
On the curvature in logarithmic plots of rate coefficients for chemical reactions
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DOI：
10.1186/1752-153x-5-22
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发表时间：
2011-05-06
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通讯作者：
Canepa, Carlo
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作者：
Canepa, Carlo
根据还原势能势垒zeta = δ u(TS)/kT，化学反应的速率系数通常表示为与e（zeta）成正比。介质的振动模式与反应坐标之间的耦合导致欧拉正则函数Q(a,zeta) = gamma (a,zeta)/ gamma (a)成比例，其中a是与反应坐标耦合的模式数。在这项工作中，几种化学反应在不同温度下的实验速率系数被拟合到以Q（a,zeta）表示的理论表达式中，以确定其有效性和普遍性的程度。新的表达式在38个案例中有29个案例与实验点的偏差较小，并且它解释了速率系数与逆温度的对数图的曲率。在没有隧道的情况下，传统理论预测这些地块的曲率相同为零。
In terms of the reduced potential energy barrier zeta = Delta u(TS)/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e(zeta).. The coupling between vibrational modes of the medium to the reaction coordinate leads to a proportionality of the regularized gamma function of Euler Q(a,zeta) = Gamma(a,zeta)/Gamma(a), with a being the number of modes coupled to the reaction coordinate. In this work, the experimental rate coefficients at various temperatures for several chemical reactions were fitted to the theoretical expression in terms of Q(a,zeta) to determine the extent of its validity and generality. The new expression affords lower deviations from the experimental points in 29 cases out of 38 and it accounts for the curvature in the logarithmic plots of rate coefficients versus inverse temperature. In the absence of tunneling, conventional theories predict the curvature of these plots to be identically zero.