Structural transitions in amorphous water ice and astrophysical implications.

@article{Jenniskens1994StructuralTI,
  title={Structural transitions in amorphous water ice and astrophysical implications.},
  author={Peter Jenniskens and D. F. Blake},
  journal={Science},
  year={1994},
  volume={265},
  pages={
          753-6
        }
}
Selected area electron diffraction is used to monitor structural changes of vapor-deposited water ice in vacuum during warm-up from 15 to 188 K. A progression of three amorphous forms of water ice is found with well-defined transitions. The formation of a high-density amorphous form (Iah) at 15 K is confirmed, and the transition to the more familiar low-density form (Ial) occurs gradually over the range 38 to 68 K. At 131 K, the ice transforms into a third amorphous form (Iar), which precedes… 

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References

SHOWING 1-10 OF 28 REFERENCES

Amorphization of cubic ice by ultraviolet irradiation

DESPITE current interest1–8 in the effects of ultraviolet radiation and high-energy particles on interstellar ice and on solid mixtures of H2O and other molecules, most attention has so far been paid

‘Melting ice’ I at 77 K and 10 kbar: a new method of making amorphous solids

Amorphous solids are made mainly by cooling the liquid below the glass transition without crystallizing it, a method used since before recorded history1, and by depositing the vapour onto a cold

High‐density amorphous ice. III. Thermal properties

The thermal properties of high‐density amorphous ice, which is made by ‘‘melting’’ ice I at 77 K by applying a pressure of ∼10 kbar, have been measured in an automated Tian–Calvet calorimeter. The

Enthalpy Changes and Heat‐Capacity Changes in the Transformations from High‐Surface‐Area Amorphous Ice to Stable Hexagonal Ice

Amorphous ice prepared by slow condensation of water vapor onto a surface cooled with liquid nitrogen or liquid hydrogen undergoes several exothermal transformations on warming. Thermal analysis by

Adsorption and Occlusion of Gases by the Low‐Temperature Forms of Ice

Water vapor condensed on a surface at −196°C in the presence of O2, N2, Ar, or CH4, forms a condensate which, on warming, evolves gas in three temperature ranges. The rate of gas evolution first goes

Evidence for a new phase of water: water II

Unstable glassy solid forms of water can be made by vapor deposition or by splat quenching the liquid. When they are annealed at about 130 K, both of the amorphous solids evidently relax into the