Crystalline and amorphous structure of astrophysical ices

• Veröffentlicht in: Физика низких температур
• Datum: 2013
• 1. Verfasser: Strazzulla, G.
• Format: Artikel
• Sprache: Englisch
• Veröffentlicht: Фізико-технічний інститут низьких температур ім. Б.І. Вєркіна НАН України 2013
• Schlagworte: 9th International Conference on Cryocrystals and Quantum Crystals
• Online Zugang: https://nasplib.isofts.kiev.ua/handle/123456789/118455
• Назва журналу: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Zitieren: Crystalline and amorphous structure of astrophysical ices / G. Strazzulla // Физика низких температур. — 2013. — Т. 39, № 5. — С. 556–559. — Бібліогр.: 26 назв. — англ.

The structure of water and other ices strongly depends on the temperature at which they formed, e.g., by vapor
 deposition. It is amorphous if ices are formed at low temperature (e.g., 10–30 K for water ice), or crystalline
 if the deposition temperature is higher (140–150 K). Ices have a “polycrystalline” structure at intermediate temperatures.
 The crystalline structure of ices can be damaged up to a complete amorphization by processes such as
 those due to energetic ion bombardment. Here I describe some experimental results obtained by ion irradiation of
 water and ammonia ices, two species particularly relevant in astrophysics. The results are discussed in the light
 of the relevance they have in astronomical environments where the actual structure of the ices depends on a
 competition between energetic processing that induce amorphization and thermal annealing that favors the transition
 towards more ordered structures.