Dielectric Relaxation of Water Adsorbed on γ-Alumina

Abstract

For several adsorbed vapors it is well known that they remain apparently ``liquid'' down to temperatures considerably below the melting point of the bulk liquid, and that on further cooling they show only a very gradual ``freezing'' over a wide temperature range. In order to shed some light on the nature of this solidification process we have measured the dielectric relaxation time of water adsorbed on γ‐alumina between room temperature and 180°K. The water content was sufficient for capillary condensation to occur. The temperature dependence of the measured relaxation rate strongly resembles that of supercooled liquids, suggesting that the solidification of capillary water may be considered as a transition from a supercooled liquid into a ``glassy'' solid state.