Schraml M, Sommer F, Pur B, Köhler W, Zimmermann G, Witusiewicz V T, Sturz L
Physikalisches Institut, Universität Bayreuth, D-95440 Bayreuth, Germany.
Access e.V., Aachen, Germany.
J Chem Phys. 2019 May 28;150(20):204508. doi: 10.1063/1.5098879.
We have determined nonisothermal diffusive transport coefficients of a succinonitrile-(d)camphor mixture with a composition of c = 0.239 wt.-frac. (d)camphor at a temperature of 318.2 K, which is close to the eutectic point. The employed experimental techniques are optical beam deflection in a Soret cell and photon correlation spectroscopy. The diffusion coefficient is D = (1.43 ± 0.04) × 10 m s, the thermodiffusion coefficient is D = (2.00 ± 0.06) × 10 m s K, and the Soret coefficient is S = (1.40 ± 0.02) × 10 K. Camphor migrates toward the lower and succinonitrile migrates toward the higher temperatures. While the diffusion coefficient is in good agreement with the literature, the Soret coefficient has been determined for the first time. Our analysis shows that a significant concentration shift can be established in the liquid mixture in the presence of a temperature gradient. The mixture has a negative separation ratio, which leads to convective instabilities if heated from above.
我们测定了温度为318.2 K（接近共晶点）、(d)樟脑质量分数c = 0.239的丁二腈-(d)樟脑混合物的非等温扩散传输系数。所采用的实验技术是索雷特池中光束偏转和光子相关光谱法。扩散系数为D = (1.43 ± 0.04) × 10⁻⁹ m²/s，热扩散系数为D_T = (2.00 ± 0.06) × 10⁻¹² m²/(s·K)，索雷特系数为S = (1.40 ± 0.02) × 10⁻³ K⁻¹。樟脑向低温处迁移，丁二腈向高温处迁移。虽然扩散系数与文献数据吻合良好，但索雷特系数是首次测定。我们的分析表明，在存在温度梯度的情况下，液体混合物中会产生显著的浓度变化。该混合物具有负分离比，如果从上方加热会导致对流不稳定性。
