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Structure and dynamics of amorphous water ice
D Laufer1, E Kochavi, A Bar-Nun
1Department of Geophysics and Planetary Sciences, Tel Aviv University, Israel.
Physical Review. B, Condensed Matter
|December 15, 1987
Summary
Amorphous water ice exhibits distinct structural forms at low temperatures, transforming irreversibly. Trapped gases like Ar, Ne, H2, and D2 reveal dynamic percolation behavior and structural changes in the ice matrix.
Area of Science:
- Materials Science
- Low-Temperature Physics
- Astrochemistry
Background:
- Amorphous water ice is a significant component of extraterrestrial environments.
- Understanding its structure and dynamics is crucial for planetary and astrophysical studies.
Purpose of the Study:
- To investigate the structure and dynamics of amorphous water ice at low temperatures.
- To explore the behavior of trapped gases (Ar, Ne, H2, D2) within the ice matrix.
Main Methods:
- Ballistic water-vapor deposition to create ice needles.
- Trapping of noble gases (Ar, Ne) and hydrogen isotopes (H2, D2) within the ice.
- Variable temperature studies (T < 85 K and 85 < T < 136.8 K) to observe phase transitions.
Main Results:
- Amorphous ice exists in at least two forms, transforming irreversibly with temperature.
- H2 and D2 penetrate ice channels readily, achieving high gas-to-ice ratios.
- Ar and Ne show dynamic percolation, leading to gas release in jets and ice matrix collapse under pressure.
Conclusions:
- The study reveals complex structural states and gas dynamics in amorphous water ice.
- Findings are relevant to understanding comets, icy moons, and interstellar ice grains.