High‐accuracy measurements of the vapor pressure of ice referenced to the triple point

Abstract

AbstractThe vapor pressure of hexagonal (Ih) water ice was measured over the temperature range 175 K to 253.4 K and referenced to the value at the triple point of water. This experiment combined a highly accurate humidity generation system containing an ice‐coated saturator (millikelvin‐level temperature control) to provide humidified streams of nitrogen to a cavity‐enhanced laser absorption spectrometer. The measured ice vapor pressures had relative standard uncertainties ranging from 0.4% to 0.7% over the entire temperature range. We demonstrate that these measurements validate thermodynamic correlations for ice vapor pressure based on integration of the Clapeyron equation. Moreover, they also indicate that some commonly used vapor pressure correlations are inaccurate and should be avoided.