Crystalline and amorphous structure of astrophysical ices

Theory of amorphous ices.

We derive a phase diagram for amorphous solids and liquid supercooled water and explain why the amorphous solids of water exist in several different forms. Application of large-deviation theory allows us to prepare such phases in computer simulations. Along with nonequilibrium transitions between the ergodic liquid and two distinct amorphous solids, we establish coexistence between these two am...

Infrared spectra and optical constants of astronomical ices: I. Amorphous and crystalline acetylene

ISAACS – interactive structure analysis of amorphous and crystalline systems

Copyright c © International Union of Crystallography Author(s) of this paper may load this reprint on their own web site or institutional repository provided that this cover page is retained. Republication of this article or its storage in electronic databases other than as specified above is not permitted without prior permission in writing from the IUCr. For further information see http://jou...

Section I. SpuItering of ices ASTROPHYSICAL IMPLICATIONS OF ICE SPUTTERING

Volatiles condensed on surfaces and condensed as major constituent, of astronomical bodies (e.g.. comets or the satellites of Saturn) arc important constituents of the solar system and, likely. the interstellar medium. In most regions of space the charged particle environments such as the solar wind and planetary magnetospheres can interact directly with the ice-covered surfaces and the icy obJ...

A Model Study of the Thermal Evolution of Astrophysical Ices

We address the question of the evolution of ices that have been exposed to radiation from stellar sources and cosmic rays. We studied in the laboratory the thermal evolution of a model ice sample: a mixture of water, hydrogen peroxide, dioxygen, and ozone produced by irradiating solid H2O2 with 50 keV H at 17 K. The changes in composition and release of volatiles during warming to 200 K were mo...