Relaxation rate in the critical dynamics of the micellar isobutoxyethanol-water system with lower consolute point.
For the isobutoxyethanol-water mixture of critical composition acoustical scaling function measurements have been performed at frequencies between 200 kHz and 3 MHz. Using the relaxation rates of concentration fluctuations as resulting from dynamic light scattering and shear viscosity measurements, the acoustical data can be well represented by the Bhattacharjee-Ferrell empirical scaling function. The theoretically predicted scaled half attenuation frequency Omega(BF)(1/2)=2.1 follows from the experiments. However, the adiabatic coupling constant, derived from the amplitude of the Bhattacharjee-Ferrell critical term, displays an unreliably strong temperature dependence. It is shown that this dependence upon temperature likely reflects a hidden low-frequency and low amplitude relaxation term in the acoustical spectra of the mixture of critical composition.
Iwanowski
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Drittes Physikalisches Institut, Georg-August-Universität, Friedrich-Hund-Platz 1, D-37077 Göttingen, Germany.
Mirzaev
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Kaatze
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