Critical behavior in broad-band dielectric relaxation on approaching the critical consolute point in ethanol-dodecane...

We present a quantitative experimental evidence for the influence of critical fluctuations on the high frequency dielectric relaxation in a binary critical mixture. The analysis clearly shows the presence of critical anomaly both for the maxima (epsilon(")(p)) and frequencies (f(p)) of loss curves peaks. For the temperature evolution of epsilon(")(p) similar relation as for the static dielectric permittivity was obtained. The temperature dependence of relaxation times can be portrayed by using the Eyring-type equation remote from the critical consolute point and shows the unusual precritical speeding up. The obtained behavior resembles that found recently in the isotropic phase of nematic liquid crystals [A. Drozd-Rzoska and S. J. Rzoska, Phys. Rev. E 65, 041701 (2002)]. Results presented agree also with the recent theoretical suggestion [S. Goodyear and S. C. Tucker, J. Chem. Phys. 111, 9673 (1999)] that relaxation in supercritical fluids may exhibit glasslike features.