EXPERIMENTAL INVESTIGATION OF THE BEHAVIOR OF THE SPECIFIC-HEAT IN FINITE SYSTEMS IN THE VICINITY OF THE CRITICAL MIXING POINT

The specific heat of a 2,6-lutidine-water mixture is measured in the v icinity of the lower critical mixing point in the bulk and in porous m edia. The results of the measurements are interpreted by finite-size s caling. In particular, a universal function of the ratio t/t [t is th e dimensionless deviation of the temperature from the specific-heat ma ximum T-m(L), and t is the characteristic dimensionless temperature, which depends on the pore size] describing the behavior of the specifi c heat in the vicinity of the critical point in porous media with diff erent pore sizes is obtained. The results obtained are consistent with the predictions of finite-size scaling and with the data from a numer ical calculation of the specific heat of the finite three-dimensional Ising model. (C) 1998 American Institute of Physics. [S1063-7761(98)02 403-2].