二成分溶液の臨界状態における超音波の異常吸収

抄録

The measurements of ultrasonic absorption have been made in binary mixtures near the critical point. Three systems of binary mixtures composed of n-hexane-nitrobenzene, diethy-leneglycoldiethylether-water and acetonitrile-water near the critical mixture were prepared. Acoustic attenuations were measured by a pulse method over the frequency range 5-21 MHz.
The temperature dependence of α/ƒ² (where α is an absorption coefficient and ƒ is frequency) at various frequencies and the frequency dependence of α/ƒ² at the critical point were investigated, and the experimental results were analyzed by Fixman's theory. (J. Chem. Phys. 36 (1962) 1961) The experimental results are in good agreement with the theory.
Short-range correlation length l and molecular friction constant β which are characteristic parameters of the critical point were calculated from the absorption data. The results are given as follows.
a) nitrobenzene-n-hexane system l=5.8Å β=2.8×10¹⁴sec^-1
b) diethyleneglycoldiethylether-water system l=2.3Å β=1.6×10¹⁷sec^-1
c) acetonitrile-water system l=2.8Åβ=6.5×10¹⁵sec^-1 Finally, the difference in the values of the two parameters (l and β) among the three systems are discussed.