Related Experiment Video
Updated: Oct 17, 2025

In Situ Monitoring of Diffusion of Guest Molecules in Porous Media Using Electron Paramagnetic Resonance Imaging
Published on: September 2, 2016
Internal Degrees of Freedom as a Basis for Isotopic Effects in Thermodiffusion
Semen N Semenov1, Martin E Schimpf2
1Institute of Biochemical Physics RAS, Kosygin Street 4, Moscow 119334, Russia.
Abstract:
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.
More Related Videos
Related Concept Videos
Degrees of Freedom
For example, suppose there are three unknown numbers whose mean is 10; although we can freely assign values to the first and second numbers, the value of the last number can not be arbitrarily...
Heat Capacities of an Ideal Gas III
Atomic Spectroscopy: Effects of Temperature
At thermal equilibrium, the relative populations of excited and ground state atoms can be estimated using the Maxwell–Boltzmann distribution. For example, an increase in temperature...
Atomic Nuclei: Nuclear Spin State Population Distribution
Isothermal Processes
An ideal gas can also undergo isothermal expansion or compression.
For example, consider 1 mole of an ideal gas inside an isolated cylinder at initial volume V...
Temperature Dependent Deformation

