Effects of Heavy Hydrogen and Oxygen on the Triple-Point Temperature of Water

• Main Authors: White, D R, Dransfield, T D, Strouse, G F, Tew, W L, Rusby, R L, Gray, J
• Format: Conference Proceeding
• Language: English
• ISSN: 0094-243X
• DOI: 10.1063/1.1627128

The temperature of the triple point of water is dependent on the isotopic composition of the water. The depletion of heavy isotopes arising from the use of fresh water rather than seawater, and from distillation and degassing of the water during manufacture of the cells, leads to cells realizing temperatures up to 80 muK lower than the definition. Five cells of varying isotopic composition were compared to evaluate the practicality of applying corrections for isotopic composition. It was found that the correction constants for deuterium and 18O measured previously by Kiyosawa were consistent with the measurements of the cells. Both of the correction constants are larger than predicted by interpolation between the triple-point temperatures of the pure isotopomers. Application of the corrections for isotopic composition eliminates a significant bias in the triple-point temperature and reduces the uncertainty in the triple-point temperature due to isotopic composition from +/-40 muK to better than +/-3 muK.