Binding energies: New values and impact on the efficiency of chemical desorption

Wakelam, Valentine; Loison, Jean‐Christophe; Méreau, Raphaël; Ruaud, M.

doi:10.1016/j.molap.2017.01.002

Cited by 205 publications

(288 citation statements)

References 54 publications

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“…This is in very good agreement with our TPD analysis which requires a temperature of 220 K for thermal desorption of formamide (Figure 8). The desorption energies published by Wakelam et al (2017), who proposed a new model to compute the binding energy of species to water ice surfaces, are adopted in the chemical model of Quénard et al (2018), which shows that formamide needs environments with temperatures of greater than 200 K to be present in the gas phase, otherwise it remains frozen on dust grains. However, our experiments show that these energies, consistent with those we found for formamide desorbed directly from the cold finger, are greater when considering adsorption on grain surfaces: using TiO 2 grains, the binding energies increased (Table 6) and the sublimation temperature was 30 K higher than that found for pure formamide (Figure 11).…”

Section: Astrophysical Context and The Importance Of Temperature-progmentioning

confidence: 99%

Photoprocessing of formamide ice: route towards prebiotic chemistry in space

Corazzi

Fedele

Poggiali

et al. 2020

A&A

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Aims. Formamide (HCONH 2 ) is the simplest molecule containing the peptide bond first detected in the gas phase in Orion-KL and SgrB 2 . In recent years, it has been observed in high temperature regions such as hot corinos, where thermal desorption is responsible for the sublimation of frozen mantles into the gas phase. The interpretation of observations can benefit from information gathered in the laboratory, where it is possible to simulate the thermal desorption process and to study formamide under simulated space conditions such as UV irradiation. Methods. Here, two laboratory analyses are reported: we studied formamide photo-stability under UV irradiation when it is adsorbed by space relevant minerals at 63 K and in the vacuum regime. We also investigated temperature programmed desorption of pure formamide ice in the presence of TiO 2 dust before and after UV irradiation. Results. Through these analyses, the effects of UV degradation and the interaction between formamide and different minerals are compared. We find that silicates, both hydrates and anhydrates, offer molecules a higher level of protection from UV degradation than mineral oxides. The desorption temperature found for pure formamide is 220 K. The desorption temperature increases to 250 K when the formamide desorbs from the surface of TiO 2 grains. Conclusions. Through the experiments outlined here, it is possible to follow the desorption of formamide and its fragments, simulate the desorption process in star forming regions and hot corinos, and constrain parameters such as the thermal desorption temperature of formamide and its fragments and the binding energies involved. Our results offer support to observational data and improve our understanding of the role of the grain surface in enriching the chemistry in space.

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Section: Astrophysical Context and The Importance Of Temperature-progmentioning

confidence: 99%

Photoprocessing of formamide ice: route towards prebiotic chemistry in space

Corazzi

Fedele

Poggiali

et al. 2020

A&A

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“…Binding energies were taken from the KIDA database (Wakelam et al 2017). 5 In total, the network contains 3695 reactions involving 401 species, 265 of which are gas-phase species, while the remaining 136 are grain surface species.…”

Section: Chemical Modeling Of P-bearing Moleculesmentioning

confidence: 99%

The Chemistry of Phosphorus-bearing Molecules under Energetic Phenomena

Jiménez-Serra

Viti

Quénard

et al. 2018

ApJ

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For decades, the detection of phosphorus-bearing molecules in the interstellar medium was restricted to high-mass star-forming regions (e.g., SgrB2 and Orion KL) and the circumstellar envelopes of evolved stars. However, recent higher-sensitivity observations have revealed that molecules such as PN and PO are present not only toward cold massive cores and low-mass star-forming regions with PO/PN ratios 1 but also toward the giant molecular clouds in the Galactic center known to be exposed to highly energetic phenomena such as intense UV radiation fields, shock waves, and cosmic rays. In this paper, we carry out a comprehensive study of the chemistry of phosphorus-bearing molecules across different astrophysical environments that cover a range of physical conditions (cold molecular dark clouds, warm clouds, and hot cores/hot corinos) and are exposed to different physical processes and energetic phenomena (proto-stellar heating, shock waves, intense UV radiation, and cosmic rays). We show how the measured PO/PN ratio (either 1, as in, e.g., hot molecular cores, or 1, as in UV strongly illuminated environments) can provide constraints on the physical conditions and energetic processing of the source. We propose that the reaction P+OH→PO+H, not included in previous works, could be an efficient gas-phase PO formation route in shocks. Our modeling provides a template with which to study the detectability of P-bearing species not only in regions in our own Galaxy but also in extragalactic sources.

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“…3 g cm −3 Dust-to-gas mass ratio D 7.09 × 10 −3 Mean molecular weight µ 2.4 a We assume T gas = T dust throughout this work. Table 2: Employed binding energies for the selected species that go through time-dependent depletion (see Wakelam et al 2017).…”

Section: Introductionmentioning

confidence: 99%

The 3D Structure of CO Depletion in High-mass Prestellar Regions

Bovino

Ferrada-Chamorro

Lupi

et al. 2019

ApJ

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Disentangling the different stages of the star-formation process, in particular in the high-mass regime, is a challenge in astrophysics. Chemical clocks could help alleviating this problem, but their evolution strongly depends on many parameters, leading to degeneracy in the interpretation of the observational data. One of these uncertainties is the degree of CO depletion. We present here the first self-consistent magneto-hydrodynamic simulations of high-mass star-forming regions at different scales, fully coupled with a non-equilibrium chemical network, which includes C-N-O bearing molecules. Depletion and desorption processes are treated time-dependently. The results show that full CO-depletion (i.e. all gas-phase CO frozen-out on the surface of dust grains), can be reached very quickly, in one third or even smaller fractions of the free-fall time, whether the collapse proceeds on slow or fast timescales. This leads to a high level of deuteration in a short time both for typical tracers like N 2 H + , as well as for the main ion H + 3 , the latter being in general larger and more extended. N 2 depletion is slightly less efficient, and no direct effects on N-bearing molecules and deuterium fractionation are observed. We show that CO depletion is not the only driver of deuteration, and that there is a strong impact on D f rac when changing the grain-size. We finally apply a two-dimensional gaussian Point Spread Function to our results to mimic observations with single-dish and interferometers. Our findings suggest that the low-values observed in high-mass star-forming clumps are in reality masking a full-depletion stage in the inner 0.1 pc region.

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Binding energies: New values and impact on the efficiency of chemical desorption

Cited by 205 publications

References 54 publications

Photoprocessing of formamide ice: route towards prebiotic chemistry in space

Photoprocessing of formamide ice: route towards prebiotic chemistry in space

The Chemistry of Phosphorus-bearing Molecules under Energetic Phenomena

The 3D Structure of CO Depletion in High-mass Prestellar Regions

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