Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
J Chem Phys. 2013 Mar 21;138(11):114503. doi: 10.1063/1.4795432.
We have measured the Soret (S(T)), diffusion (D), and thermal diffusion (D(T)) coefficients of the three binary benchmark mixtures of dodecane (C12), isobutylbenzene, and 1,2,3,4-tetrahydronaphthalene at T = 25°C for at least five different concentrations each, covering the entire binary composition range. The two different optical techniques employed, optical beam deflection and optical digital interferometry, are in good to excellent agreement. Additionally, we have carefully measured the optical contrast factors (∂n/∂c)(p, T) and (∂n/∂T)(p, c). If the temperature and composition dependence of the mixture density is taken into account, both the Lorentz-Lorenz (LL) and the Looyenga (LO) equations give reasonable predictions of (∂n/∂c)(p, T). In case of (∂n/∂T)(p, c), only the LO equation yields good predictions in case of constant molecular polarizabilities α(i) of the pure compounds. If the apparent temperature dependence of α(i) is explicitly taken into account, excellent predictions are obtained both from the LL and the LO equations.
我们已经测量了十二烷（C12）、异丁基苯和 1,2,3,4-四氢萘这三种二元基准混合物在 T=25°C 时的 Soret（S(T)）、扩散（D）和热扩散（D(T)）系数，每种混合物至少测量了五个不同浓度，涵盖了整个二元组成范围。所采用的两种不同的光学技术，即光束偏转和光学数字干涉测量法，具有良好到优异的一致性。此外，我们还仔细测量了光学对比系数（∂n/∂c）（p，T）和（∂n/∂T）（p，c）。如果考虑混合物密度的温度和组成依赖性，洛伦兹-洛伦茨（LL）和洛伊恩加（LO）方程都可以合理地预测（∂n/∂c）（p，T）。对于（∂n/∂T）（p，c），只有在纯化合物的分子极化率α（i）恒定时，LO 方程才能给出良好的预测。如果明确考虑α（i）的表观温度依赖性，则从 LL 和 LO 方程都可以得到很好的预测。
