Institute of Biochemical Physics RAS, Kosygin Street 4, Moscow 119334, Russia.
Department of Chemistry, Boise State University, Boise, Idaho 83725, United States.
J Phys Chem B. 2021 Oct 21;125(41):11512-11519. doi: 10.1021/acs.jpcb.1c07034. Epub 2021 Oct 12.
We present a model that relates isotope effects in thermodiffusion to changes in internal degrees of freedom associated with rotational and vibrational motion. The model uses general material transport equations for binary non-isothermal liquid systems, derived using non-equilibrium thermodynamics in our previous work. The equilibrium chemical potentials of the components at constant pressure are derived using statistical mechanics. In evaluating the model, we use experimental data on changes in the Soret coefficient of various hydrocarbons in perprotonated and perdeuterated cyclohexane. We also compare predictions of the model with experimental data on the Soret coefficient in isotopic mixtures. In all cases, the model is consistent with experimental data and computations.
我们提出了一个模型，该模型将热扩散中的同位素效应与与旋转和振动运动相关的内部自由度变化联系起来。该模型使用我们之前工作中使用非平衡热力学推导的二元非等温液体系统的通用物质输运方程。使用统计力学推导出各成分在恒压下的平衡化学势。在评估模型时，我们使用了关于各种碳氢化合物在质子化和氘化环己烷中 Soret 系数变化的实验数据。我们还将模型的预测与同位素混合物中 Soret 系数的实验数据进行了比较。在所有情况下，该模型都与实验数据和计算结果一致。
