Kinetics of the OCN<sup>−</sup>and HOCN formation from the HNCO + H<sub>2</sub>O thermal reaction in interstellar ice analogs

Theulé, Patrice; Duvernay, Fabrice; Ilmane, A.; Hasegawa, Tetsuo; Morata, Ó.; Coussan, S.; Danger, Grégoire; Chiavassa, Thierry

doi:10.1051/0004-6361/201016051

Cited by 41 publications

(41 citation statements)

References 24 publications

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“…10 shows no conclusive correlation between OCN − ice and HNCO in the gas phase with respect to CH 3 OH. Qualitatively, such a correlation is expected since HNCO and OCN − are linked through efficient thermal acid-base chemistry within the ice (e.g., Demyk et al 1998;van Broekhuizen et al 2004;Theule et al 2011). The lack of a correlation may therefore simply be due to the difficulty determining Fig.…”

Section: An Ice-gas Connection?mentioning

confidence: 99%

“…11 for temperatures between 20 K and 100 K. Since the model does not treat ion chemistry in the ice, a full conversion rate of HNCO ice into OCN − has been assumed based on the efficient HNCO to OCN − conversion derived experimentally by Demyk et al (1998), van Broekhuizen et al (2004, Theule et al (2011), among others. The resulting complex molecular gas abundances are regulated by a combination of temperature and initial ice composition.…”

Section: The Ice-gas Connection: Observations Vs Theorymentioning

confidence: 99%

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Complex organic molecules in organic-poor massive young stellar objects

Fayolle

Öberg

Garrod

et al. 2015

A&A

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Context. Massive young stellar objects (MYSOs) with hot cores are classic sources of complex organic molecules. The origins of these molecules in such sources, as well as the small-and large-scale differentiation between nitrogen-and oxygen-bearing complex species, are poorly understood. Aims. We aim to use complex molecule abundances toward a chemically less explored class of MYSOs with weak hot organic emission lines to constrain the impact of hot molecular cores and initial ice conditions on the chemical composition toward MYSOs. Methods. We use the IRAM 30 m and the Submillimeter Array to search for complex organic molecules over 8−16 GHz in the 1 mm atmospheric window toward three MYSOs with known ice abundances, but without luminous molecular hot cores. Results. Complex molecules are detected toward all three sources at comparable abundances with respect to CH 3 OH to classical hot core sources. The relative importance of CH 3 CHO, CH 3 CCH, CH 3 OCH 3 , CH 3 CN, and HNCO differ between the organic-poor MYSOs and hot cores, however. Furthermore, the N-bearing molecules are generally concentrated toward the source centers, while most O-and C-bearing molecules are present both in the center and in the colder envelope. Gas-phase HNCO/CH 3 OH ratios are tentatively correlated with the ratios of NH 3 ice over CH 3 OH ice in the same lines of sight, which is consistent with new gas-grain model predictions. Conclusions. Hot cores are not required to form complex organic molecules, and source temperature and initial ice composition both seem to affect complex organic distributions toward MYSOs. To quantify the relative impact of temperature and initial conditions requires, however, a larger spatially resolved survey of MYSOs with ice detections.

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Section: An Ice-gas Connection?mentioning

confidence: 99%

Section: The Ice-gas Connection: Observations Vs Theorymentioning

confidence: 99%

Complex organic molecules in organic-poor massive young stellar objects

Fayolle

Öberg

Garrod

et al. 2015

A&A

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“…3.1), and of H 2 CO mixed with H 2 O (Sect. 3.3), were performed in Marseille on the RING experimental set-up (Theule et al 2011). Briefly, a gold plated copper surface is maintained at low temperature using a closed-cycle helium cryostat (ARS Cryo, model DE-204 SB, 4 K cryogenerator) within a high-vacuum chamber at a few 10 −9 mbar.…”

Section: Methodsmentioning

confidence: 99%

The desorption of H₂CO from interstellar grains analogues

Noble

Theulé

Mispelaer

et al. 2012

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Context. Much of the formaldehyde (H 2 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. Aims. We study experimentally the thermal desorption of H 2 CO from bare silicate surfaces, from water ice surfaces and from bulk water ice in order to model its desorption from interstellar grains. 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 2 CO is bound to other H 2 CO molecules; (ii.) the submonolayer regime where H 2 CO is bound on top of a water ice surface; (iii.) the mixed submonolayer regime where H 2 CO is bound to a silicate surface; and (iv.) the multilayer regime in water ice, where H 2 CO is embedded within a H 2 O matrix. Results. In the submonolayer regime, we find the zeroth-order desorption kinetic parameters ν 0 = 10 28 mol cm −2 s −1 and E = 31.0 +/− 0.9 kJ mol −1 for desorption from an olivine surface. The zeroth-order desorption kinetic parameters are ν 0 = 10 28 mol cm −2 s −1 and E = 27.1 +/− 0.5 kJ mol −1 for desorption from a water ice surface in the submonolayer regime. In a H 2 CO:H 2 O mixture, the desorption is in competition with the H 2 CO + H 2 O reaction, which produces polyoxymethylene, the polymer of H 2 CO. This polymerization reaction prevents the volcano desorption and co-desorption from happening. Conclusions. H 2 CO is only desorbed from interstellar ices via a dominant sub-monolayer desorption process (E = 27.1 +/− 0.5 kJ mol −1 ). The H 2 CO which has not desorbed during this sub-monolayer desorption polymerises upon reaction with H 2 O, and does not desorb as H 2 CO at higher temperature.

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“…In practice the diffusion timescale corresponds to 10 2 to 10 6 s. For a ASW thickness of few hundred layers, this time interval corresponds to diffusion coefficients of 10 −15 cm 2 s −1 to 10 −11 cm 2 s −1 , which corresponds to a certain temperature range according to the molecule. Another time constraint is added if the molecule is reacting with H 2 O, as it is the case for H 2 CO forming HOCH 2 OH (Noble et al 2012) and for HNCO forming H 3 O + OCN − (Theulé et al 2011).…”

Section: The Experimental Protocolmentioning

confidence: 99%

“…The experiments were performed using our RING experimental set-up as described elsewhere (Theulé et al 2011). A goldplated copper surface is maintained at low temperature using a closed-cycle helium cryostat (ARS Cryo, model DE-204 SB, 4 K cryogenerator) within a high-vacuum chamber at a few 10 −9 mbar.…”

Section: The Experimental Set-upmentioning

confidence: 99%

Diffusion measurements of CO, HNCO, H₂CO, and NH₃in amorphous water ice

Mispelaer¹,

Theulé²,

Aouididi³

et al. 2013

A&A

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Context. Water is the major component of the interstellar ice mantle. In interstellar ice, chemical reactivity is limited by the diffusion of the reacting molecules, which are usually present at abundances of a few percent with respect to water. Aims. We want to study the thermal diffusion of H 2 CO, NH 3 , HNCO, and CO in amorphous water ice experimentally to account for the mobility of these molecules in the interstellar grain ice mantle. Methods. In laboratory experiments performed at fixed temperatures, the diffusion of molecules in ice analogues was monitored by Fourier transform infrared spectroscopy. Diffusion coefficients were extracted from isothermal experiments using Fick's second law of diffusion. Results. We measured the surface diffusion coefficients and their dependence with the temperature in porous amorphous ice for HNCO, H 2 CO, NH 3 , and CO. They range from 10 −15 to 10 −11 cm 2 s −1 for HNCO, H 2 CO, and NH 3 between 110 K and 140 K, and between 5-8 × 10 −13 cm 2 s −1 for CO between 35 K and 40 K. The bulk diffusion coefficients in compact amorphous ice are too low to be measured by our technique and a 10 −15 cm 2 s −1 upper limit can be estimated. The amorphous ice framework reorganization at low temperature is also put in evidence. Conclusions. Surface diffusion of molecular species in amorphous ice can be experimentally measured, while their bulk diffusion may be slower than the ice mantle desorption kinetics.

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Kinetics of the OCN⁻and HOCN formation from the HNCO + H₂O thermal reaction in interstellar ice analogs

Cited by 41 publications

References 24 publications

Complex organic molecules in organic-poor massive young stellar objects

Complex organic molecules in organic-poor massive young stellar objects

The desorption of H₂CO from interstellar grains analogues

Diffusion measurements of CO, HNCO, H₂CO, and NH₃in amorphous water ice

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Kinetics of the OCN−and HOCN formation from the HNCO + H2O thermal reaction in interstellar ice analogs

Cited by 41 publications

References 24 publications

Complex organic molecules in organic-poor massive young stellar objects

Complex organic molecules in organic-poor massive young stellar objects

The desorption of H2CO from interstellar grains analogues

Diffusion measurements of CO, HNCO, H2CO, and NH3in amorphous water ice

Contact Info

Product

Resources

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Kinetics of the OCN⁻and HOCN formation from the HNCO + H₂O thermal reaction in interstellar ice analogs

The desorption of H₂CO from interstellar grains analogues

Diffusion measurements of CO, HNCO, H₂CO, and NH₃in amorphous water ice