The Ice Survey Opportunity of ISO

Dartois, E.

doi:10.1007/s11214-005-8059-9

Cited by 120 publications

(96 citation statements)

References 70 publications

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“…As the temperature continues to decrease, reaching temperatures as low as 8 K in some objects, 3 a mantle composed of many different molecules can be observed. 4 H 2 O is the major component of these icy mantles and as such has been the focus of much research. 2 More recently, H 2 O ice has been directly detected on comet 67P/Churyumov-Gerasimenko by the Rosetta mission 5 confirming the icy grain origins of these primitive bodies.…”

Section: Introductionmentioning

confidence: 99%

Peeling the astronomical onion

Rosu-Finsen

Marchione

Salter

et al. 2016

Phys. Chem. Chem. Phys.

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Journal Name ARTICLEThis journal is © The Royal Society of Chemistry 20xxJ. Name., 2013, 00, 1-3 | 1 Water ice is the most abundant solid in the Universe. Understanding the formation, structure and multiplicity of physicochemical roles for water ice in the cold, dense interstellar environments in which it is predominantly observed is a crucial quest for astrochemistry as these are regions active in star and planet formation. Intuitively, we would expect the mobility of water molecules deposited or synthesised on dust grain surfaces at temperatures below 50 K to be very limited. This work delves into the thermally-activated mobility of H2O molecules on model interstellar grain surfaces. The energy required to initiate this process is studied by reflection-absorption infrared spectroscopy of small quantities of water on amorphous silica and highly oriented pyrolytic graphite surfaces as the surface is annealed. Strongly nonArrhenius behaviour is observed with an activation energy of 2 kJ mol -1 on the silica surface below 25 K and 0 kJ mol -1 on both surfaces between 25 and 100 K. The astrophysical implication of these results is that on timescales shorter than that estimated for the formation of a complete monolayer of water ice on a grain, aggregation of water ice will result in a nonuniform coating of water, hence leaving bare grain surface exposed. Other molecules can thus be formed or adsorbed on this bare surface.

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Section: Introductionmentioning

confidence: 99%

Peeling the astronomical onion

Rosu-Finsen

Marchione

Salter

et al. 2016

Phys. Chem. Chem. Phys.

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“…Some of them are cold (~10 K) and dense (10 4 -10 6 cm -3 ) regions where gaseous species heavier than hydrogen and helium freeze out onto the grains. Beside H2O and CO, other species constitute the inventory of icy mantles such as CO2, CH3OH, CH4, H2CO and NH3, 3,4 as a result of the gasgrain interactions occurring on the surface of interstellar dust. The most important and abundant molecular species as well, H2, is formed likewise thanks to reactions occurring on amorphous water ice in molecular clouds 5,6 .…”

Section: Introductionmentioning

confidence: 99%

Changes in the morphology of interstellar ice analogues after hydrogen atom exposure

Accolla

Congiu

Dulieu

et al. 2011

Phys. Chem. Chem. Phys.

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The morphology of water ice in the interstellar medium is still an open question. Although accretion of gaseous water could not be the only possible origin of the observed icy mantles covering dust grains in cold molecular clouds, it is well known that water accreted from the gas phase on surfaces kept at 10 K forms ice films that exhibit a very high porosity. It is also known that in the dark clouds H2 formation occurs on the icy surface of dust grains and that part of the energy (4.48 eV) released when adsorbed atoms react to form H2 is deposited in the ice. The experimental study described in the present work focuses on how relevant changes of the ice morphology result from atomic hydrogen exposure and subsequent recombination. Using the temperature-programmed desorption (TPD) technique and a method of inversion analysis of TPD spectra, we show that there is an exponential decrease in the porosity of the amorphous water ice sample following D-atom irradiation. This decrease is inversely proportional to the thickness of the ice and has a value of φ0 = 2 × 10 16 D-atoms cm -2 per layer of H2O. We also use a model which confirms that the binding sites on the porous ice are destroyed regardless of their energy depth, and that the reduction of the porosity corresponds in fact to a reduction of the effective area. This reduction appears to be compatible with the fraction of D 2 formation energy transferred to the porous ice network. Under interstellar conditions, this effect is likely to be efficient and, together with other compaction processes, provides a good argument to believe that interstellar ice is amorphous and non-porous. 1.IntroductionAmorphous solid water (ASW) is reputed to be the most abundant form of water in the Universe, thanks to its propensity for forming, molecule after molecule, as a deposit on interstellar dust particles. 1,2 The accretion of icy mantles (predominantly constituted by ASW) on silicate and carbonaceous dust grains takes place in interstellar molecular clouds. Some of them are cold (~10 K) and dense (10 4 -10 6 cm -3 ) regions where gaseous species heavier than hydrogen and helium freeze out onto the grains. Beside H2O and CO, other species constitute the inventory of icy mantles such as CO2, CH3OH, CH4, H2CO and NH3, 3,4 as a result of the gasgrain interactions occurring on the surface of interstellar dust. The most important and abundant molecular species as well, H2, is formed likewise thanks to reactions occurring on amorphous water ice in molecular clouds 5,6 . In addition, a significant fraction of the gas phase species is constituted by atomic hydrogen whose abundance is mostly governed by the destruction of H2 due to cosmic rays. It has been evaluated that, in dense clouds, the average number density ratio of atomic hydrogen component compared to the molecular one is ~ 0.1%. 7 In a dark cloud, atomic hydrogen thus represents the third most abundant gas-phase species, after H2 and He.Along with atoms and molecules available in the gas-phase and the condensed/adsorbed speci...

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“…These cold (10-50 K) clouds are composed of interstellar grains that show large amounts of dirty ices in astronomical infrared vibrational spectra, which are mainly composed of water but also of other molecules such as CO, CO 2 , CH 3 OH, NH 3 , etc. (Dartois 2005). During the grain evolution, this material will undergo numerous chemical modifications caused by ionic and VUV irradiations as well as thermal effects.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of nitrile formation from VUV photochemistry of interstellar ices analogs: acetonitrile and amino acetonitrile

Danger

Bossa

Marcellus

et al. 2010

A&A

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Context. The study of the chemical reactivity in interstellar ices in astrophysical environments is an important tool for understanding the origin of the organic matter in molecular clouds, in protoplanetary disks, and possibly, as a final destination, in our solar system. The laboratory simulations of the reactivity in ice analogs provide important information for understanding the reactivity in these environments. Here, we used these experimental simulations to trace some formation pathways of two nitriles, acetonitrile and amino acetonitrile, which are two potential precursors of amino acids in astrophysical environments. Aims. The purpose of this work is to present the first experimental approach for the formation of acetonitrile and amino acetonitrile in interstellar-like conditions. Methods. We use Fourier Transform InfraRed (FTIR) spectroscopy and mass spectrometry to study the formation at 20 K of acetonitrile CH 3 CN from VUV irradiation of ethylamine and of amino acetonitrile NH 2 CH 2 CN from VUV irradiation of ammonia: acetonitrile mixture. Isotopic substitutions are used to confirm identifications. Results. We demonstrate that acetonitrile can be formed at 20 K from the VUV irradiation of ethylamine with a yield of 4%. Furthermore, in presence of ammonia, at 20 K and under VUV irradiation, the acetonitrile can lead to the amino acetonitrile formation. These results suggest that acetonitrile and amino acetonitrile can be formed in astrophysical environments that are submitted to VUV irradiations.

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The Ice Survey Opportunity of ISO

Cited by 120 publications

References 70 publications

Peeling the astronomical onion

Peeling the astronomical onion

Changes in the morphology of interstellar ice analogues after hydrogen atom exposure

Experimental investigation of nitrile formation from VUV photochemistry of interstellar ices analogs: acetonitrile and amino acetonitrile

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