Dielectric Anomaly and the Vapor-Liquid Phase Transition in Mercury

Abstract

Measurements are reported of the pressure dependence of the real part of the dielectric constant of subcritical and supercritical Hg vapor. Abrupt upward deviations from normal Clausius-Mosotti behavior, which are exhibited in an extremely narrow pressure range in the subcritical vapor phase, indicate that the vapor-liquid phase transition near the critical region is preceded by a heretofore undetected "plasma transition." It is concluded that the dielectric anomaly is caused by the formation of dense, charged thermodynamically stable droplets.