Dynamics of Entropy Fluctuations in a Critical Binary Mixture

Abstract

Using a very sophisticated light-beating spectrometer and a new correlation technique, we have measured the relaxation time of entropy fluctuations in a critical binary mixture in the reduced temperature range of $4\times {10}^{-6\mathrm{}}<~t<~{10}^{-1\mathrm{}}$. In the hydrodynamic regime this relaxation time, which is proportional to the specific heat at constant pressure and critical concentration, is found to behave as $t^{-\alpha }(1+{\mathrm{Bt}}^{+\mathrm{x}})$ with a critical exponent $\alpha =0.059\mathrm{}\pm 0.003$ and $x=1.05\mathrm{}\pm 0.15$.