Ultra-Low-Temperature Reactions of Carbon Atoms With Hydrogen Molecules

Krasnokutski, Serge A.; Kühn, Martin; Renzler, Michael; Jäger, Cornelia; Henning, Th.; Scheier, P.

doi:10.3847/2041-8205/818/2/l31

Cited by 22 publications

(13 citation statements)

References 37 publications

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“…In the past, the reaction of C atoms with H2 molecules was considered to be unimportant due to a large activation barrier. However, our experiential studies 27,39 confirmed the results of quantumchemical calculations 46 that shows the zero energy barrier for this reaction, which was found to be important for the surface chemistry of the ISM. 47 Reactions of С atoms with molecular and atomic hydrogen have noticeable difference.…”

Section: The Formation Of Biomolecules Via C Atoms Condensationsupporting

confidence: 81%

“…Currently, there are only few considered surface reactions of C atoms. For example, only simplest surface reactions of C atom are included into KIDA 33,34 [35][36][37][38][39][40][41][42][43] The ability of C atoms to be barrierlessly incorporated into existing C-C bonds 36,40 creates the conditions for the growth in the molecular size and the complexity of the molecular structure at low temperatures. There are several models of the surface chemistry, where carbon atoms were involved in the formation of COMs.…”

Section: The Formation Of Biomolecules Via C Atoms Condensationmentioning

confidence: 99%

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Did life originate from low-temperature areas of the Universe?

Krasnokutski

2021

Low Temperature Physics

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The biological molecules delivered to Earth on the board of meteorites and comets were called one of the possible causes of the origin of life. Therefore, our understanding of the routes of formation of biomolecules in space should shed the light on the possibility of the existence of habitable extrasolar planets. The large abundance of organic molecules is found in the space regions with the lowest temperature. Different routes of the organics formation in these areas were suggested. In this article, we demonstrate that complex organic molecules same as important biological molecules can be formed due to the reaction of C atoms with the mantels of molecular ices covering refractory dust grains present in the interstellar medium (ISM). Having four valence electrons, C atoms act as glue joining simple nonorganic molecules and converting them into organic matter. The formation of many molecules is barrierless and thus can happen at low temperature. The barrierless reaction C + NH3 + CO → NH2CHCO attracts particular interest. The product of this reaction is an isomer of the central residue of a peptide chain and expected to be efficiently formed in the translucent molecular clouds. The polymerization of these molecules leads to the formation of proteins that according to some theories are life's first molecules. Considering a high abundance of atomic carbon in the ISM, we expect a high efficiency of the formation of a large variety of different organic molecules, and show why the amount of organic material formed by condensation of atomic carbon may be underestimated.

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Section: The Formation Of Biomolecules Via C Atoms Condensationsupporting

confidence: 81%

Section: The Formation Of Biomolecules Via C Atoms Condensationmentioning

confidence: 99%

Did life originate from low-temperature areas of the Universe?

Krasnokutski

2021

Low Temperature Physics

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“…Most recently, with the development of a source of pure C atoms, studies have become feasible of chemical reactions of C atoms under HND conditions. Nanocalorimetry has been applied in a demonstration of the occurrence of the reaction of C atoms with H2 by a barrierless insertion to form HCH [497] and high-resolution mass-spectrometric studies have explored the reaction of C atoms with C60 [498]. The experiments with C60 molecules have shown that C atoms can bridge bond onto C60 without cage growth to form carbenes of the type C60C: and higher members C60(C:)n with n up to 6, and so dramatically transform the chemical reactivity of the fullerene.…”

Section: Neutral Reactionsmentioning

confidence: 99%

Cold physics and chemistry: Collisions, ionization and reactions inside helium nanodroplets close to zero K

et al. 2018

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“…The liquid helium acts like a chemically inert dust surface because it absorbs the excess of reaction energy. The reaction C + H 2 + M → CH 2 + M was found to be fast at T = 0.37 K (Krasnokutski et al 2016;Henning & Krasnokutski 2019). This demonstrates the absence of the energy barrier in the surface reaction pathway and ensures a high reaction rate at low temperatures in the ISM.…”

Section: Introductionmentioning

confidence: 80%

Sensitivity of gas-grain chemical models to surface reaction barriers

Simončič

Semenov

Krasnokutski

et al. 2020

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Context. The feasibility of contemporary gas-grain astrochemical models depends on the availability of accurate kinetics data, in particular, for surface processes. Aims. We study the sensitivity of gas-grain chemical models to the energy barrier Ea of the important surface reaction between some of the most abundant species: C and H2 (surface C + surface H2 → surface CH2). Methods. We used the gas-grain code ALCHEMIC to model the time-dependent chemical evolution over a 2D grid of densities (nH ∈ 103, 1012 cm−3) and temperatures (T ∈ 10, 300 K), assuming UV-dark (AV = 20 mag) and partly UV-irradiated (AV = 3 mag) conditions that are typical of the dense interstellar medium. We considered two values for the energy barrier of the surface reaction, Ea = 2500 K (as originally implemented in the networks) and Ea = 0 K (as measured in the laboratory and computed by quantum chemistry simulations). Results. We find that if the C + H2 → CH2 surface reaction is barrierless, a more rapid conversion of the surface carbon atoms into methane ice occurs. Overproduction of the CHn hydrocarbon ices affects the surface formation of more complex hydrocarbons, cyanides and nitriles, and CS-bearing species at low temperatures ≲10−15 K. The surface hydrogenation of CO and hence the synthesis of complex (organic) molecules become affected as well. As a result, important species whose abundances may change by more than a factor of two at 1 Myr include atomic carbon, small mono-carbonic (C1) and di-carbonic (C2) hydrocarbons, CO2, CN, HCN, HNC, HNCO, CS, H2CO, H2CS, CH2CO, and CH3OH (in either gas and/or ice). The abundances of key species, CO, H2O, and N2 as well as O, HCO+, N2H+, NH3, NO, and most of the S-bearing molecules, remain almost unaffected. Conclusions. Further accurate laboratory measurements and quantum chemical calculations of the surface reaction barriers will be crucial to improve the accuracy of astrochemical models.

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Ultra-Low-Temperature Reactions of Carbon Atoms With Hydrogen Molecules

Cited by 22 publications

References 37 publications

Did life originate from low-temperature areas of the Universe?

Did life originate from low-temperature areas of the Universe?

Cold physics and chemistry: Collisions, ionization and reactions inside helium nanodroplets close to zero K

Sensitivity of gas-grain chemical models to surface reaction barriers

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