Electron induced chemistry: a new frontier in astrochemistry

Mason, Nigel J.; Nair, B. G.; Jheeta, Sohan; Szymańska, Ewelina

doi:10.1039/c4fd00004h

Cited by 77 publications

(83 citation statements)

References 31 publications

(38 reference statements)

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“…the penetration depth for 2 keV electrons is ∼100 nm, while it may be as low as 20 monolayers for 100 eV electrons. 37,202 VUV penetration depths are similar to that of keV electrons.…”

Section: Uv Vs Electronsmentioning

confidence: 65%

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

2016

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The interstellar medium is characterized by a rich and diverse chemistry. Many of its complex organic molecules are proposed to form through radical chemistry in icy grain mantles.Radicals form readily when interstellar ices (composed of water and other volatiles) are exposed to UV photons and other sources of dissociative radiation, and if sufficiently mobile the radicals can react to form larger, more complex molecules. The resulting complex organic molecules (COMs) accompany star and planet formation, and may eventually seed the origins of life on nascent planets. Experiments of increasing sophistication have demonstrated that known interstellar COMs as well as the prebiotically interesting amino acids can form through ice photochemistry. We review these experiments and discuss the qualitative and quantitative kinetic and mechanistic constraints they have provided. We finally compare the effects of UV radiation with those of three other potential sources of radical production and chemistry in interstellar ices: electrons, ions and X-rays.

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“…the penetration depth for 2 keV electrons is ∼100 nm, while it may be as low as 20 monolayers for 100 eV electrons. 37,202 VUV penetration depths are similar to that of keV electrons.…”

Section: Uv Vs Electronsmentioning

confidence: 65%

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

2016

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“…Formamide is readily formed and the resonance like feature between 6 and 12 eV is characteristic of the synthesis by reactants prepared in a dissociative electron attachment process [71]. Similar experiments have shown that as many as 15 products can be formed by electron irradiation of pure methanol ices [72] including ethylene glycol and methyl formate whilst formamide HCONH2 is formed in irradiation of binary mixtures of ammonia and methanol ice and the simplest amino acid glycine from irradiation of a methylamine and carbon dioxide ice [73]. Thus, electron induced synthesis of simple cometary ices may be a route to formation of several of the organic species observed in surface material from comet 67P.…”

Section: Possibility Of Electron Induced Surface Chemistrymentioning

confidence: 61%

Rosetta Mission: Electron Scattering Cross Sections—Data Needs and Coverage in BEAMDB Database

Marinković

Bredehöft

Vujčić

et al. 2017

Atoms

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Abstract:The emission of [O I] lines in the coma of Comet 67P/Churyumov-Gerasimenko during the Rosetta mission have been explained by electron impact dissociation of water rather than the process of photodissociation. This is the direct evidence for the role of electron induced processing has been seen on such a body. Analysis of other emission features is handicapped by a lack of detailed knowledge of electron impact cross sections which highlights the need for a broad range of electron scattering data from the molecular systems detected on the comet. In this paper, we present an overview of the needs for electron scattering data relevant for the understanding of observations in coma, the tenuous atmosphere and on the surface of 67P/Churyumov-Gerasimenko during the Rosetta mission. The relevant observations for elucidating the role of electrons come from optical spectra, particle analysis using the ion and electron sensors and mass spectrometry measurements. To model these processes electron impact data should be collated and reviewed in an electron scattering database and an example is given in the BEAMD, which is a part of a larger consortium of Virtual Atomic and Molecular Data Centre-VAMDC.

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“…sugars, amino acids, aldehydes or amphiphilic molecules. [48][49][50][51] In fact, laboratory experiments simulating the UV processed ice mixtures showed that the presence of ammonia in these ices is essential for a stabilization of light aldehydes in a harsh space environment. 48 Similarly, the importance of methanol presence in astrochemical ices is critical to the production of amphiphilic molecules.…”

Section: Introductionmentioning

confidence: 99%

Ionization of Ammonia Nanoices with Adsorbed Methanol Molecules

et al. 2018

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Large ammonia clusters represent a model system of ices which are omnipresent throughout the space. The interaction of ammonia ices with other hydrogen-boding molecules such as methanol or water and their behavior upon an ionization are thus relevant in the astrochemical context. In this study, ammonia clusters (NH3)N with the mean size N¯ ≈230 were prepared in molecular beams and passed through a pickup cell in which methanol molecules were adsorbed. At the highest exploited pickup pressures, the average composition of (NH3)N(CH3OH)M clusters was estimated to be N:M≈ 210:10. On the other hand, the electron ionization of these clusters yielded about 75% of methanol-containing fragments (NH3)n(CH3OH)mH + compared to 25% contribution of pure ammonia (NH3)nH + ions. Based on this substantial disproportion, we propose the following ionization mechanism: The prevailing ammonia is ionized in most cases, resulting in NH + 4 core solvated most likely with four ammonia molecules, yielding the well-known "magic number" structure (NH 3 ) 4 NH + 4 .The methanol molecules exhibit strong propensity for sticking to the fragment ion. We have also considered mechanisms of intracluster reactions. In most cases, proton transfer between ammonia units take place. The theoretical calculations suggested the proton transfer either from the methyl group or from the hydroxyl group of the ionized methanol molecule to ammonia to be the energetically open channels. However, the experiments with selectively deuterated methanols did not show any evidence for the D + transfer from the CD 3 group. The proton transfer from the hydroxyl group could not be excluded entirely nor confirmed unambiguously by the experiment.

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Electron induced chemistry: a new frontier in astrochemistry

Cited by 77 publications

References 31 publications

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Photochemistry and Astrochemistry: Photochemical Pathways to Interstellar Complex Organic Molecules

Rosetta Mission: Electron Scattering Cross Sections—Data Needs and Coverage in BEAMDB Database

Ionization of Ammonia Nanoices with Adsorbed Methanol Molecules

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