The pretransitional anomaly of dielectric permittivity in the isotropic phase of nematogens and in the homogeneous phase of critical solutions

The pretransitional behaviour of static dielectric permittivity in the isot ropic phase of nematogens and in the homogeneous phase of a weakly off-crit ical binary solution is compared. The pretransitional anomalies are describ ed by analogous relations, with critical exponents phi = 1 - alpha approxim ate to 0.50 and phi = 1 - alpha approximate to 0.89, respectively. Tests we re conducted for pressure paths approaching the virtual critical point The specific-heat-like dependences of derivatives of dielectric permittivities in both systems have been shown. This result agrees with the dependence sug gested for critical mixtures by Mistura (1973 J. Chern. Phys. 59 4563). Res ults obtained point to the validity of the recently formulated hypothesis o n the fluid-like critical behaviour of the isotropic-nematic transition (Mu khejee P K er al 1995 Phys. Rev E 51 1570, Mukherjee P K 1998 J. Phys.: Con dens. Matter 10 9191).