Astrochemistry: Synthesis and Modelling

Wakelam, Valentine; Cuppen, H. M.; Herbst, Eric

doi:10.1007/978-3-642-31730-9_4

Cited by 10 publications

(10 citation statements)

References 93 publications

(122 reference statements)

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“…Furthermore, we also see that the size of the Langevin rates of anion formation, usually employed in modelling studies: Wakelam and et. al.…”

Section: Present Conclusionsupporting

confidence: 55%

“…substantially larger than the corresponding rates of REA formation by electron attachment Herbst and Osamura (2009);Kawaguchi et al (1995);Khamesian et al (2016). All reaction rates, however, remain smaller than the Langevin formation rates usually employed in astrochemical databases and which are, as mentioned earlier, of the order of 10 −9 cm 3 mol −1 s −1 as given by Wakelam and et. al.…”

Section: Modelling the Reaction Ratesmentioning

confidence: 81%

“…(iv) One should also note that the Langevin rates listed in the KIDA database of Wakelam and et. al.…”

Section: Modelling the Reaction Ratesmentioning

confidence: 99%

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Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7

Gianturco

Satta

Yurtsever

et al. 2017

ApJ

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We investigate the relative efficiencies of low-temperature chemical reactions in the Interstellar medium (ISM) with H − anion reacting in the gas phase with cyanopolyyne neutral molecules, leading to the formation of anionic C x N − linear chains of different length and of H 2 . All the reactions turn out to be without barriers, highly exothermic reactions which provide a chemical route to the formation of anionic chains of the same length . Some of the anions have been observed in the dark molecular clouds and in the diffuse interstellar envelopes.Quantum calculations are carried for the corresponding reactive potential energy surfaces (RPESs) for all the odd-numbered members of the series (x=1, 3, 5, 7). We employ the Minimum Energy paths (MEPs) to obtain the relevant Transition State (TS) configurations and use the latter within the Variational Transition State ( VTS) model to obtain the chemical rates. The present results indicate that, at typical temperatures around 100 K, a set of significantly larger rate values exists for x=3 and x=5, while are smaller for CN − and C 7 N − . At those temperatures, however, all the rates turn out to be larger than the estimates in the current literature for the Radiative Electron Attachment (REA) rates, thus indicating the greater importance of the present chemical path with respect to REA processes at those temperatures. The physical reasons for our findings are discussed in detail and linked with the existing observational findings.where the length of the odd-numbered chains goes in our study from x = 1 to x = 7 .

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“…Furthermore, we also see that the size of the Langevin rates of anion formation, usually employed in modelling studies: Wakelam and et. al.…”

Section: Present Conclusionsupporting

confidence: 55%

Section: Modelling the Reaction Ratesmentioning

confidence: 81%

See 1 more Smart Citation

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7

Gianturco

Satta

Yurtsever

et al. 2017

ApJ

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“…Astrochemical models aiming at studying the molecular complexity in dense and shielded interstellar regions (cold cores for instance) focus on a detailed description of the complex chemical network at play, and on the time-dependent aspect of this chemistry (as some chemical timescales become comparable to the dynamical lifetime of these clouds). Such models thus solve kinetic differential equations in which each individual chemical and physical process is assigned a rate (Wakelam et al, 2013).…”

Section: Kinetic Models For Complex Chemistrymentioning

confidence: 99%

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

Wakelam

Bron

Cazaux

et al. 2017

Molecular Astrophysics

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231

201

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a b s t r a c tMolecular hydrogen is the most abundant molecule in the universe. It is the first one to form and survive photo-dissociation in tenuous environments. Its formation involves catalytic reactions on the surface of interstellar grains. The micro-physics of the formation process has been investigated intensively in the last 20 years, in parallel of new astrophysical observational and modeling progresses. In the perspectives of the probable revolution brought by the future satellite JWST, this article has been written to present what we think we know about the H 2 formation in a variety of interstellar environments.

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“…Those models solve the kinetic differential equations to compute the species abundances as a function of time in the gas-phase and at the surface of the grains starting from an initial composition and assuming a set of parameters (mostly the physical conditions and the chemical network). We refer to Wakelam et al (2012) for a complete review on chemical modeling. As an example, Fig.…”

Section: Introduction To Interstellar Chemistry and Chemical Modelsmentioning

confidence: 99%

Carbon Interstellar Chemistry: Theory versus Observations

Wakelam

2013

Proc. IAU

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Abstract. To study the interstellar chemical composition and interpret molecular observations, astrochemists have built chemical models over the years. Those models compute the composition of the gas and the icy mantles of interstellar grains taking in account a large number of processes, such as chemical reactions in the gas-phase, interactions with grain surfaces (sticking and evaporation) and chemical reactions at the surface of the grains. Those models rely on a number of parameters (physical parameters of the medium and intrinsic chemical parameters such as rate coefficients), which are estimated with an associated uncertainty. From a chemical point of view, those uncertainties are mainly due to an incomplete knowledge of the efficiency of the processes in the interstellar conditions. Many studies in the recent and past years have been undertaken to improve this knowledge, either using experimental or theoretical results in physico-chemistry.

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Astrochemistry: Synthesis and Modelling

Cited by 10 publications

References 93 publications

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

Carbon Interstellar Chemistry: Theory versus Observations

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Astrochemistry: Synthesis and Modelling

Cited by 10 publications

References 93 publications

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H− with HCxN for Odd-valued x from 1 to 7

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H− with HCxN for Odd-valued x from 1 to 7

H 2 formation on interstellar dust grains: The viewpoints of theory, experiments, models and observations

Carbon Interstellar Chemistry: Theory versus Observations

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Product

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Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7

Formation of Anionic C, N-bearing Chains in the Interstellar Medium via Reactions of H⁻ with HC_xN for Odd-valued x from 1 to 7