We have developed a new double-pass optical beam deflection instrument for the measurement of diffusion, thermodiffusion and Soret coefficients in liquid mixtures. The increased sensitivity of the instrument results from a second passage of the readout laser beam through the Soret cell containing the sample. An elegant description of the total beam deflection is achieved by means of a transfer matrix formalism. The higher sensitivity allows for a reduction of the length of the detection arm and a compact and stiff design of the instrument. The performance of the new apparatus is demonstrated by its application to polymer analysis for the determination of the molar mass distribution of the polymer from the distribution of diffusion rates by means of the CONTIN algorithm.

中文翻译：

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用于测量液体混合物中扩散、热扩散和索雷系数的双通光束偏转仪及其在聚合物分析中的应用

我们开发了一种新型双通光束偏转仪器，用于测量液体混合物中的扩散、热扩散和索雷系数。仪器灵敏度的提高是由于读出激光束第二次穿过包含样品的 Soret 池。总光束偏转的优雅描述是通过传递矩阵形式实现的。更高的灵敏度可以缩短检测臂的长度，并实现仪器的紧凑和刚性设计。新设备的性能通过其在聚合物分析中的应用得到证明，通过 CONTIN 算法根据扩散速率的分布确定聚合物的摩尔质量分布。