The Static Dielectric Constant of Liquid Water between 274 K and 418 K near the Saturated Vapor Pressure

Jean Hamelin,^{1 }James B. Mehl,^{1,2 }and Michael R. Moldover^{1}

The complex dielectric constant (relative electric permittivity) of liquid water was redetermined in the temperature range 274-418 K at pressures less that 440 kPa. In this work, the complex dielectric constant was deduced from measurements of the resonant frequencies of a novel, re-entrant, two-mode, radio-frequency resonator. The frequencies ranged from 23 MHz to 84 MHz and were well within the low-frequency limit for the static dielectric constant of water. The data for the static dielectric constant for two water samples differing in conductivity by a factor of 3.6 and for the two resonant modes differing in frequency by a factor of 2.6 were simultaneously fit by a third degree polynomial function with a remarkably small residual standard deviation of 0.0055. The present data are consistent with previously published data; however, they are more precise and internally consistent. The present apparatus was also tested with cyclohexane and yielded values in excellent agreement with previously published values.