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Random encounters dominate water-water interactions at supercritical conditions
Katja Mauelshagen1, Philipp Schienbein2,3, Inga Kolling1
1Lehrstuhl für Physikalische Chemie II, Ruhr-Universität Bochum, 44780 Bochum, Germany.
Science Advances
|March 14, 2025
Summary
Supercritical water
Area of Science:
- Geochemistry and Physical Chemistry
Background:
- Supercritical water, prevalent in Earth's crust, is a potential green solvent.
- Water's hydrogen bonding at ambient conditions is well-established.
- The nature of hydrogen bonding in supercritical water remains debated.
Purpose of the Study:
- To investigate intermolecular interactions in supercritical water.
- To clarify the hydrogen bonding status of water under extreme conditions.
Main Methods:
- Terahertz (THz) spectroscopy to probe water's intermolecular interactions.
- Ab initio molecular dynamics simulations for theoretical insights.
Main Results:
- Spectroscopic evidence of the liquid-gas phase transition below the critical point.
- THz spectra of high-temperature gas and supercritical water are identical at equal densities.
- Simulations reveal orientationally random water-water contacts in supercritical conditions.
Conclusions:
- Supercritical water exhibits random intermolecular contacts, differing from ambient conditions.
- THz spectroscopy is effective for studying water under extreme conditions.
- Findings contribute to understanding water's behavior in Earth's crust and its solvent properties.
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