Scaling frequency in the critical sound attenuation of binary liquids

For the ethanol-dodecane and methanol-cyclohexane mixtures of critical composition ultrasonic attenuation, shear viscosity, and dynamic light scattering data are evaluated to yield the scaled half-attenuation frequency Ω1/2 of the Bhattacharjee-Ferrell dynamic scaling model as well as the Folk-Moser and the Onuki scaling functions. Within the limits of experimental error, the experimental half-attenuation frequency values for the former model (Ω1/2BF = 2.0 ± 0.5) agree with the theoretical prediction. The Ω1/2 values derived for the Folk-Moser and the Onuki scaling functions exhibit systematic deviations from the theoretical values Ω1/2FM = 3.1 and Ω1/2On = 6.2. The results show that, at least for systems without crossover to elementary chemical reactions, the frequency scale in the dynamic scaling model, which had been obtained by including a special hydrodynamic effect, is in accord with experimental evidence.

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