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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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Danger, Gregoire
Aix-Marseille University
in Cooperation with on an Cooperation-Score of 37%
Topics
Publications (5/5 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
- 2013Importance of thermal reactivity for hexamethylenetetramine formation from simulated interstellar icescitations
- 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 desorption of H<SUB>2</SUB>CO from interstellar grains analogues
Abstract
Context. Much of the formaldehyde (H<SUB>2</SUB>CO) is formed from the hydrogenation of CO on interstellar dust grains, and is released in the gas phase in hot core regions. Radio-astronomical observations in these regions are directly related to its desorption from grains. <BR /> Aims: We study experimentally the thermal desorption of H<SUB>2</SUB>CO from bare silicate surfaces, from water ice surfaces and from bulk water ice in order to model its desorption from interstellar grains. <BR /> Methods: Temperature-programmed desorption experiments, monitored by mass spectrometry, and Fourier transform infrared spectroscopy are performed in the laboratory to determine the thermal desorption energies in: (i.) the multilayer regime where H<SUB>2</SUB>CO is bound to other H<SUB>2</SUB>CO molecules; (ii.) the submonolayer regime where H<SUB>2</SUB>CO is bound on top of a water ice surface; (iii.) the mixed submonolayer regime where H<SUB>2</SUB>CO is bound to a silicate surface; and (iv.) the multilayer regime in water ice, where H<SUB>2</SUB>CO is embedded within a H<SUB>2</SUB>O matrix. <BR /> Results: In the submonolayer regime, we find the zeroth-order desorption kinetic parameters ν<SUB>0</SUB> = 10<SUP>28</SUP> mol cm<SUP>-2</SUP> s<SUP>-1</SUP> and E = 31.0 +/-0.9 kJ mol<SUP>-1</SUP> for desorption from an olivine surface. The zeroth-order desorption kinetic parameters are ν<SUB>0</SUB> = 10<SUP>28</SUP> mol cm<SUP>-2</SUP> s<SUP>-1</SUP> and E = 27.1 +/-0.5 kJ mol<SUP>-1</SUP> for desorption from a water ice surface in the submonolayer regime. In a H<SUB>2</SUB>CO:H<SUB>2</SUB>O mixture, the desorption is in competition with the H<SUB>2</SUB>CO + H<SUB>2</SUB>O reaction, which produces polyoxymethylene, the polymer of H<SUB>2</SUB>CO. This polymerization reaction prevents the volcano desorption and co-desorption from happening. <BR /> Conclusions: H<SUB>2</SUB>CO is only desorbed from interstellar ices via a dominant sub-monolayer desorption process (E = 27.1 +/ - 0.5 kJ mol<SUP>-1</SUP>). The H<SUB>2</SUB>CO which has not desorbed during this sub-monolayer desorption polymerises upon reaction with H<SUB>2</SUB>O, and does not desorb as H<SUB>2</SUB>CO at higher temperature....