Laboratory studies of desorption from model interstellar ices using surface science methodologies

Collings, Mark P.; McCoustra, Martin R. S.

doi:10.1051/eas/1258052

Cited by 3 publications

(2 citation statements)

References 37 publications

(33 reference statements)

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“…We propose that the missing organics problems can be solved if the elements forming organic compounds (i.e., C, H, O, and N) desorb from LIC dust near the Sun. There are several energetic processes that could help C, H, O, and N to desorb from organic refractory material in the interstellar medium (Baragiola et al 2005;Collings & McCoustra 2012). Among these processes, we consider that exothermic reactions would release sufficient energy to sublimate organic materials when interstellar dust is heated by solar radiation to a temperature that is high enough to trigger the reactions.…”

Section: Modelmentioning

confidence: 99%

Organic matter in interstellar dust lost at the approach to the heliosphere

Kimura

Postberg

Altobelli

et al. 2020

A&A

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Aims. We tackle the conundrums of organic materials missing from interstellar dust when measured inside the Solar System, while undoubtedly existing in the local interstellar cloud (LIC), which surrounds the Solar System. Methods. We present a theoretical argument that organic compounds sublimate almost instantaneously by exothermic reactions, when solar insolation triggers the recombination of free radicals or the rearrangement of carbon bonds in the compounds. Results. It turns out that the triggering temperature lies in the range of 20–50 K by considering that sublimation of organic materials takes place beyond the so-called filtration region of interstellar neutral atoms. We find that in-situ measurements of LIC dust in the Solar System result in an overestimate for the gas-to-dust mass ratio of the LIC, unless the sublimation of organic materials is taken into account. We also find that previous measurements of interstellar pickup ions have determined the total elemental abundances of gas and organic materials, instead of interstellar gas alone. Conclusions. We conclude that LIC organic matter suffers from sublimation en route to the heliosphere, implying that our understanding of LIC dust from space missions is incomplete. Since space missions inside the orbit of Saturn cannot give any information on the organic substances of LIC dust, one must await a future exploration mission to the inner edge of the Oort cloud for a thorough understanding of organic substances in the LIC. Once our model for the sublimation of interstellar organic matter by exothermic chemical reactions of free radicals is confirmed, the hypothesis of panspermia from the diffuse interstellar medium is ruled out.

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Section: Modelmentioning

confidence: 99%

Organic matter in interstellar dust lost at the approach to the heliosphere

Kimura

Postberg

Altobelli

et al. 2020

A&A

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“…On the other hand, while the UV radiation from external sources is strongly attenuated, cosmic rays (MeV -TeV) can influence the chemistry of the gas and solid components of the interstellar matter, as they can deeply penetrate into the cloud (Gaches et al 2019). One of the physico-chemical effects caused by the incidence of cosmic rays onto dust grains is the ejection of atoms and molecules from the ice mantle to the gas phase (Herbst & Cuppen 2006;Collings & McCoustra 2012;Iqbal & Wakelam 2018). Charged particles (projectiles) moving through a solid collide randomly with the target species along their track through Coulomb interactions with the nuclei and electrons of the target.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature chemistry induced by cosmic rays: positive and negative ion desorption from nitrile-bearing astrophysical ice analogues

Ribeiro

Almeida

Wolff

et al. 2019

Monthly Notices of the Royal Astronomical Society

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In cold core of dark molecular clouds, where the UV radiation from external sources is strongly attenuated, cosmic rays can induce chemical reactions on the surface of icecovered grains promoting the ejection of the processed material to the gas phase. We report the positive and negative secondary ion emission from pure CH 3 CN, C 2 H 3 CN and i−C 3 H 7 CN ices due to the bombardment of heavy ions ( 252 Cf fission fragments), simulating the incidence of cosmic rays onto icy surfaces. The secondary ions emitted from each sample were analysed by time-of-flight mass spectrometry (TOF-MS), using Plasma Desorption Mass Spectrometry (PDMS) technique. Several ionic species were identified, indicating strong fragmentation on the frozen surface. Proton-transfer processes are suggested to play a role for positive ion desorption, as evidenced by the protonated RCNH + parent molecules and (RCN) n H + ionic clusters. The high electron affinity of the cyano radical seems to contribute to the strong emission of CN − , as well as anions attributed to the CH m CN − fragment and (RCN) n CN − cluster series. Sputtering and desorption of ion clusters (positive and negative) induced by heavy ion bombardment are suggested to constitute a route by which new neutral or ionised molecular species may be delivered to the gas phase where thermal desorption is negligible.

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The synthesis of large interstellar molecules

Herbst

2017

International Reviews in Physical Chemistry

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Laboratory studies of desorption from model interstellar ices using surface science methodologies

Cited by 3 publications

References 37 publications

Organic matter in interstellar dust lost at the approach to the heliosphere

Organic matter in interstellar dust lost at the approach to the heliosphere

Low-temperature chemistry induced by cosmic rays: positive and negative ion desorption from nitrile-bearing astrophysical ice analogues

The synthesis of large interstellar molecules

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