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Journal Articles The Journal of Chemical Physics Year : 2024

Isotope effect on the anomalies of water: A corresponding states analysis

Frédéric Caupin
Bruno Issenmann

Abstract

Light and heavy water show similar anomalies in thermodynamic and dynamic properties, with a consistent trend of anomalies occurring at higher temperatures in heavy water. Viscosity also increases faster upon cooling in heavy water, causing a giant isotope effect, with a viscosity ratio near 2.4 at 244 K. While a simple temperature shift apparently helps in collapsing experimental data for both isotopes, it lacks a clear justification, changes value with the property considered, and requires additional ad hoc scaling factors. Here, we use a corresponding states analysis based on the possible existence of a liquid–liquid critical point in supercooled water. This provides a coherent framework that leads to the collapse of thermodynamic data. The ratio between the dynamic properties of the isotopes is strongly reduced. In particular, the decoupling between viscosity η and self-diffusion D, measured as a function of temperature T by the Stokes–Einstein ratio Dη/T, is found to collapse after applying the corresponding states analysis. Our results are consistent with simulations and suggest that the various isotope effects mirror the one on the liquid–liquid transition.

Dates and versions

hal-04584443 , version 1 (23-05-2024)

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Frédéric Caupin, Pierre Ragueneau, Bruno Issenmann. Isotope effect on the anomalies of water: A corresponding states analysis. The Journal of Chemical Physics, 2024, 160 (19), ⟨10.1063/5.0205452⟩. ⟨hal-04584443⟩
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