Gebhardt M, Köhler W
Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
J Chem Phys. 2015 Oct 28;143(16):164511. doi: 10.1063/1.4934718.
We have investigated thermodiffusion in ternary mixtures of dodecane (nC12), isobutylbenzene (IBB), and 1,2,3,4-tetrahydronaphthalene (THN) by means of two-color optical beam deflection over the entire ternary composition space. The Soret and the thermodiffusion coefficients S(T,i)'(c1,c2) and D(T,i)'(c1,c2), respectively, have been determined for all three components i and fitted by smooth approximating polynomials in the independent concentrations c1 (nC12) and c2 (THN). Both the Soret and the thermodiffusion coefficient are negative for nC12 and positive for THN over all compositions. In case of IBB, they change sign, being negative for THN-rich and positive for nC12-rich mixtures. Both the positive and negative signs and the sign change are in agreement with qualitative predictions based on the recently introduced thermophobicity concept [S. Hartmann et al., Phys. Rev. Lett. 109, 065901 (2012); J. Chem. Phys. 141, 134503 (2014)]. For isothermal diffusion, a mean diffusion coefficient D̄ but neither the diffusion matrix nor its eigenvalues could be determined.
我们通过在整个三元组成空间上的双色光束偏转法，研究了十二烷（nC12）、异丁基苯（IBB）和1,2,3,4 - 四氢萘（THN）三元混合物中的热扩散。分别测定了所有三种组分i的索雷特系数和热扩散系数S(T,i)'(c1,c2) 以及D(T,i)'(c1,c2)，并通过独立浓度c1（nC12）和c2（THN）的光滑近似多项式进行拟合。在所有组成中，nC12的索雷特系数和热扩散系数均为负，THN的则为正。对于IBB，它们会改变符号，在富含THN的混合物中为负，在富含nC12的混合物中为正。正负符号以及符号变化均与基于最近引入的热疏性概念的定性预测一致 [S. Hartmann等人，《物理评论快报》109, 065901 (2012); 《化学物理杂志》141, 134503 (2014)]。对于等温扩散，无法确定平均扩散系数D̄，也无法确定扩散矩阵及其特征值。
