Porosity measurements of interstellar ice mixtures using optical laser interference and extended effective medium approximations
Autor: | T. Triemstra, D. M. Paardekooper, J.-B. Bossa, K. Isokoski, Stéphanie Cazaux, Alexander G. G. M. Tielens, M. Bonnin, E. van der Linden, Harold Linnartz |
---|---|
Přispěvatelé: | Astronomy |
Jazyk: | angličtina |
Rok vydání: | 2014 |
Předmět: |
Astrochemistry
Composite number Infrared spectroscopy FOS: Physical sciences 02 engineering and technology Astrophysics 01 natural sciences 0103 physical sciences Deposition (phase transition) Porosity 010303 astronomy & astrophysics Instrumentation and Methods for Astrophysics (astro-ph.IM) Physics Earth and Planetary Astrophysics (astro-ph.EP) Condensed Matter - Materials Science astrochemistry Interstellar ice Materials Science (cond-mat.mtrl-sci) Astronomy and Astrophysics 021001 nanoscience & nanotechnology ISM: molecules Space and Planetary Science Chemical physics Effective medium approximations methods: laboratory: solid state 0210 nano-technology Astrophysics - Instrumentation and Methods for Astrophysics Refractive index Astrophysics - Earth and Planetary Astrophysics |
Zdroj: | Astronomy & astrophysics, 561:A136. EDP Sciences Astronomy & Astrophysics, 561, A136 Astronomy & Astrophysics |
ISSN: | 1432-0746 0004-6361 |
Popis: | Aims. This article aims to provide an alternative method of measuring the porosity of multi-phase composite ices from their refractive indices and of characterising how the abundance of a premixed contaminant (e.g., CO2) affects the porosity of water-rich ice mixtures during omni-directional deposition. Methods. We combine optical laser interference and extended effective medium approximations (EMAs) to measure the porosity of three astrophysically relevant ice mixtures: H2O:CO2=10:1, 4:1, and 2:1. Infrared spectroscopy is used as a benchmarking test of this new laboratory-based method. Results. By independently monitoring the O-H dangling modes of the different water-rich ice mixtures, we confirm the porosities predicted by the extended EMAs. We also demonstrate that CO2 premixed with water in the gas phase does not significantly affect the ice morphology during omni-directional deposition, as long as the physical conditions favourable to segregation are not reached. We propose a mechanism in which CO2 molecules diffuse on the surface of the growing ice sample prior to being incorporated into the bulk and then fill the pores partly or completely, depending on the relative abundance and the growth temperature. Comment: 9 pages, 6 figures, 1 table. Accepted for publication in A&A |
Databáze: | OpenAIRE |
Externí odkaz: |