Laboratoire des Fluides Complexes-UMR 5150, Université de Pau et des Pays de l'Adour, BP 1155, 64013 Pau Cedex, France.
J Chem Phys. 2011 Jul 21;135(3):034901. doi: 10.1063/1.3610368.
In the present work binary mixtures of varying concentrations of two miscible hydrocarbons, 1,2,3,4-tetrahydronaphtalene (THN) and n-dodecane (C12), are subjected to increasing pressure up to 50 MPa in order to investigate the dependence of the so-called concentration contrast factor (CF), i.e., (∂n/∂c)(p, T), on pressure level. The refractive index is measured by means of a Mach-Zehnder interferometer. The setup and experimental procedure are validated with different pure fluids in the same pressure range. The refractive index of the THN-C12 mixture is found to vary both over pressure and concentration, and the concentration CF is found to exponentially decrease as the pressure is increased. The measured values of the refractive index and the concentration CFs are compared with values obtained by two different theoretical predictions, the well-known Lorentz-Lorenz formula and an alternative one proposed by Looyenga. While the measured refractive indices agree very well with predictions given by Looyenga, the measured concentration CFs show deviations from the latter of the order of 6% and more than the double from the Lorentz-Lorenz predictions.
在目前的工作中，我们将两种互溶的碳氢化合物——1,2,3,4-四氢萘（THN）和正十二烷（C12）——的不同浓度的二元混合物在高达 50 MPa 的压力下进行了升压处理，以研究所谓的浓度对比因子（CF），即（∂n/∂c）（p，T），随压力水平的变化关系。折射率通过马赫-曾德尔干涉仪进行测量。该设置和实验程序通过在相同压力范围内的不同纯流体进行了验证。发现 THN-C12 混合物的折射率既随压力又随浓度而变化，并且随着压力的增加，浓度 CF 呈指数下降。所测量的折射率和浓度 CF 值与两种不同理论预测值（著名的 Lorentz-Lorenz 公式和 Looyenga 提出的替代公式）进行了比较。虽然测量的折射率与 Looyenga 的预测非常吻合，但测量的浓度 CF 值与后者相比存在 6%左右的偏差，与 Lorentz-Lorenz 预测值相比偏差超过两倍。
