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Published on: June 28, 2017
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Supercooled Liquid Water Diffusivity at Temperatures near the Glass Transition Temperature.
R Scott Smith1, Wyatt A Thornley1, Greg A Kimmel1
1Physical Sciences Division, Pacific Northwest National Laboratory, PO Box 999, Mail Stop J7-10, Richland, Washington 99352, United States.
The Journal of Physical Chemistry Letters
|March 20, 2025
Summary
Researchers measured the diffusion of supercooled water using isotopically layered films. Results show liquid-like motion near the glass transition, supporting a continuous liquid state above it.
Area of Science:
- Physical Chemistry
- Materials Science
- Thermodynamics
Background:
- Understanding the behavior of water near its glass transition is crucial for various scientific fields.
- Amorphous solid water exhibits complex properties that are not fully understood, particularly its transition to a liquid state.
Purpose of the Study:
- To measure the translational diffusivity of deeply supercooled liquid water.
- To investigate the nature of the liquid state of amorphous water above its glass transition temperature.
Main Methods:
- Preparation of isotopically layered amorphous solid water films (H2^18O and H2^16O).
- Controlled heating at very slow rates (down to 10^-4 K/s) to decouple diffusion and crystallization.
- Analysis of intermixing using numerical simulations of desorption spectra to extract diffusivities.
Main Results:
- Obtained translational diffusivities consistent with liquid-like motion.
- Observed this motion at temperatures near and above the proposed glass transition temperature (Tg) of 136 K.
- Diffusion measurements were performed well below the crystallization onset temperature.
Conclusions:
- The findings support the hypothesis that the melt of amorphous water is thermodynamically continuous with normal supercooled liquid water.
- Liquid-like translational motion persists in amorphous water close to its glass transition.
- This study provides critical experimental data on water's behavior in a deeply supercooled regime.
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