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| Naji, M. |
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| Motta, Antonella |
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| Aletan, Dirar |
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| Mohamed, Tarek |
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| Ertürk, Emre |
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| Taccardi, Nicola |
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| Kononenko, Denys |
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| Petrov, R. H. | Madrid |
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| Alshaaer, Mazen | Brussels |
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| Bih, L. |
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| Casati, R. |
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| Muller, Hermance |
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| Kočí, Jan | Prague |
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| Šuljagić, Marija |
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| Kalteremidou, Kalliopi-Artemi | Brussels |
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| Azam, Siraj |
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| Ospanova, Alyiya |
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| Blanpain, Bart |
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| Ali, M. A. |
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| Popa, V. |
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| Rančić, M. |
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| Ollier, Nadège |
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| Azevedo, Nuno Monteiro |
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| Landes, Michael |
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| Rignanese, Gian-Marco |
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Theule, P.
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (4/4 displayed)
- 2015Hydrogenation at low temperatures does not always lead to saturation: the case of HNCOcitations
- 2014Formaldehyde chemistry in cometary ices: implication for the Rosetta mission
- 2013The thermal reactivity of HCN and NH<SUB>3</SUB> in interstellar ice analoguescitations
- 2012The desorption of H<SUB>2</SUB>CO from interstellar grains analoguescitations
Places of action
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article
The thermal reactivity of HCN and NH<SUB>3</SUB> in interstellar ice analogues
Abstract
HCN is a molecule central to interstellar chemistry, since it is the simplest molecule containing a carbon-nitrogen bond and its solid state chemistry is rich. The aim of this work was to study the NH<SUB>3</SUB> + HCN → NH<SUP>+</SUP><SUB>4</SUB>CN<SUP>-</SUP> thermal reaction in interstellar ice analogues. Laboratory experiments based on Fourier transform infrared spectroscopy and mass spectrometry were performed to characterize the NH<SUP>+</SUP><SUB>4</SUB>CN<SUP>-</SUP> reaction product and its formation kinetics. This reaction is purely thermal and can occur at low temperatures in interstellar ices without requiring non-thermal processing by photons, electrons or cosmic rays. The reaction rate constant has a temperature dependence of k(T) = 0.016<SUP>+ 0.010</SUP><SUB>- 0.006</SUB> s^{-1}exp (-2.7± 0.4 text{kJ mol}^{-1}/RT) when NH<SUB>3</SUB> is much more abundant than HCN. When both reactants are diluted in water ice, the reaction is slowed down. We have estimated the CN<SUP>-</SUP> ion band strength to be A_{text{CN}^-} = 1.8 ± 1.5 × 10<SUP>-17</SUP> cm molecule<SUP>-1</SUP> at both 20 and 140 K. NH<SUP>+</SUP><SUB>4</SUB>CN<SUP>-</SUP> exhibits zeroth-order multilayer desorption kinetics with a rate of k_{text{des}}(T) = 10<SUP>28</SUP> molecule cm<SUP>-2</SUP> s^{-1}exp (-38.0± 1.4text{ kJ mol}^{-1}/RT). The NH<SUB>3</SUB> + HCN → NH<SUP>+</SUP><SUB>4</SUB>CN<SUP>-</SUP> thermal reaction is of primary importance because (i) it decreases the amount of HCN available to be hydrogenated into CH<SUB>2</SUB>NH, (ii) the NH<SUP>+</SUP><SUB>4</SUB> and CN<SUP>-</SUP> ions react with species such as H<SUB>2</SUB>CO and CH<SUB>2</SUB>NH to form complex molecules and (iii) NH<SUP>+</SUP><SUB>4</SUB>CN<SUP>-</SUP> is a reservoir of NH<SUB>3</SUB> and HCN, which can be made available to a high-temperature chemistry....