用毛细管成像法测量液相扩散系数——等折射率薄层测量方法

本文提出了一种测量液相扩散系数的新方法. 该方法用透明毛细管构成液相扩散池, 利用毛细管成像法特有的折射率空间分辨测量能力, 通过直接观察和记录扩散介质的等折射率薄层在毛细管中的移动规律, 基于扩散过程遵循的Fick第二定律计算出液相扩散系数. 在25 ℃下研究了丙三醇和纯水间的扩散过程, 扩散系数的测量值与全息干涉法的文献报道值之间的相对误差为4.47%, 论文同时分析了折射率测量精度和毛细管管壁黏滞力对扩散系数的影响. 用毛细管成像法测量液相扩散系数具有样品需要量少、测量速度快、系统稳定性好的特点, 为快速测定微量样品的扩散系数提供了一种有效的新方法. 关键词： 扩散系数 液体折射率 毛细管成像法

Measuring the diffusion coefficient of liquids by capillary imaging method: equivalent refractive index method

A novel method for measuring the diffusion coefficient of liquids is introduced in this paper. A transparency capillary is used as both diffusive pool and imaging element, spatially resolving ability of the capillary in measuring refractive index of liquid is utilized to observe and record diffusive process directly, diffusion coefficient of liquid is calculated based on Fick second law and acquired experimental data. With the new method, the diffusive process of pure glycerol in water at 25 ℃ is investigated, the obtained diffusion coefficient is 0.898×10^-5 cm²/s, which is of a relative error 4.47% compared with the literature value measured by the holographic interference. The influence of measurement accuracy of refractive index and capillary viscosity on measuring result is also analyzed. The method is characterized by micro-quantity sample required, faster measurement and better stability, which opens a new way to measure diffusion coefficient of liquid medium.
Keywords： diffusion coefficient of liquid refractive index capillary imaging method