Canepa Carlo
Dipartimento di Chimica Generale e Chimica Organica, Università di Torino Corso Massimo d'Azeglio 48, 10125 Torino, Italy.
Chem Cent J. 2011 May 6;5(1):22. doi: 10.1186/1752-153X-5-22.
In terms of the reduced potential energy barrier ζ = ΔuTS/kT, the rate coefficients for chemical reactions are usually expressed as proportional to e-ζ. 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,ζ) = Γ(a,ζ)/Γ(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,ζ) 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.
就降低的势能垒ζ = ΔuTS/kT而言，化学反应的速率系数通常表示为与e-ζ成比例。介质振动模式与反应坐标之间的耦合导致欧拉正则化伽马函数Q(a,ζ) = Γ(a,ζ)/Γ(a)成比例，其中a是与反应坐标耦合的模式数量。在这项工作中，将几种化学反应在不同温度下的实验速率系数拟合到以Q(a,ζ)表示的理论表达式中，以确定其有效性和通用性的程度。新表达式在38个案例中的29个案例中与实验点的偏差较小，并且它解释了速率系数与绝对温度倒数的对数图中的曲率。在没有隧穿的情况下，传统理论预测这些图的曲率恒为零。
