Cosmic ray impact on astrophysical ices: laboratory studies on heavy ion irradiation of methane

Barros, A. L. F. de; Bordalo, V.; Duarte, Eduardo Seperuelo; Silveira, E.F. da; Domaracka, A.; Rothard, H.; Boduch, P.

doi:10.1051/0004-6361/201016021

Cited by 59 publications

(42 citation statements)

References 48 publications

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“…Specifically, the discovery of abundant C 2 H 6 in comet C/1996 B2 Hyakutake by Mumma et al [17] led them to suggest H atom addition to C 2 H 2 , acetylene, as a source of C 2 H 6 . We have confirmed that the sequence [18]:…”

Section: H 2 O and Hydrocarbon Experimentssupporting

confidence: 69%

“…High stopping power interactions are more efficient to dissociate the matrix molecules and also, as a consequence, to produce new chemical species. The same average value n ∼ 3 / 2 , was observed as well as in experiments with pure HCOOH [40], pure CH 4 ices [18], and in the mixture H 2 O:H 2 CO for the H 2 CO molecule [39]. Measurements using other matrixes are being performed in order to verify if this law can be generalized.…”

Section: Discussionmentioning

confidence: 93%

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Radiolysis of astrophysical ices by heavy ion irradiation: Destruction cross section measurement

Barros

Boduch

Domaracka

et al. 2012

Low Temperature Physics

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Many solar system objects, such as planets and their satellites, dust grains in rings, and comets, are known to either be made of ices or to have icy surfaces. These ices are exposed to ionizing radiation including keV, MeV and GeV ions from solar wind or cosmic rays. Moreover, icy dust grains are present in interstellar space and in particular in dense molecular clouds. Radiation effects include radiolysis (the destruction of molecules leading to formation of radicals), the formation of new molecules following radiolysis, the desorption or sputtering of atoms or molecules from the surface, compaction of porous ices, and phase changes. This review discusses the application of infrared spectroscopy FTIR to study the evolution of the chemical composition of ices containing the most abundant molecular species found in the solar system and interstellar medium, such as H 2 O, CO, CO 2 and hydrocarbons. We focus on the evolution of chemical composition with ion fluence in order to deduce the corresponding destruction and formation cross sections. Although initial approach focused on product identification, it became increasingly necessary to work toward a comprehensive understanding of ice chemistry. The abundances of these molecules in different phases of ice mantles provide important clues to the chemical processes in dense interstellar clouds, and therefore it is of importance to accurately measure the quantities such as dissociation and formation cross sections of the infrared features of these molecules. We also are able to obtain the scaling of these cross sections with deposited energy.

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Section: H 2 O and Hydrocarbon Experimentssupporting

confidence: 69%

Section: Discussionmentioning

confidence: 93%

Radiolysis of astrophysical ices by heavy ion irradiation: Destruction cross section measurement

Barros

Boduch

Domaracka

et al. 2012

Low Temperature Physics

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“…The increase of the CH 4 molecules due to irradiation was followed through its FTIR peaks at 1302–3009 cm −1 . The A ‐values used were 5.1 and 6.4 × 10 −18 cm molecule −1 , respectively (Gerakines et al 1996; de Barros et al 2011). The column density determined after irradiation is N = 3.61 × 10 16 molecules cm −2 for the 1302 cm −1 band.…”

Section: Laboratory Resultsmentioning

confidence: 99%

“…A detailed description of the experimental apparatus can be found e.g. in Pilling et al (2010) and de Barros et al (2011). In the centre of a high vacuum chamber (10 −8 mbar), a closed cycle helium cryostat kept the CsI substrate at 15 K. The pure methanol sample (Aldrich, 99.9 per cent) was purified with several freeze‐thaw cycles to remove any volatile gas from the sample.…”

Section: Methodsmentioning

confidence: 99%

Radiolysis of frozen methanol by heavy cosmic ray and energetic solar particle analogues

Barros

Domaracka

Andrade

et al. 2011

Monthly Notices of the Royal Astronomical Society

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The chemical and physical effects induced by fast heavy ion irradiation on frozen pure methanol (CH3OH) at 15 K were studied. These energetic ions can simulate the energy transfer processes that occur by cosmic ray irradiation of interstellar ices, comets and icy Solar system bodies. The analysis was made by infrared spectroscopy (Fourier transform infrared) before and after irradiation, with 16‐MeV 16O5+, 220‐MeV 16O7+, 606‐MeV 65Zn20+ and 774‐MeV 86Kr31+ ion beams. Integrated values of the absorbance of the main methanol bands were determined. The induced CH3OH dissociation gives rise to the formation of molecular species, particularly H2CO, CH2OH, CH4, CO, CO2, HCO and HCOOCH3. Their formation and dissociation cross‐sections were determined. H2CO and CH4 molecules are in general the most abundant new products of the four beams analysed. Except for the HCO and CH2OH species, cross‐sections increased with the electronic stopping power, roughly as σ∼S3/2e. The G values for CH3OH destruction by fast heavy ion irradiation with Zn and Kr beams were found to be considerably larger than those for oxygen, helium or hydrogen. As an astrophysical implication, the S3/2e power law should be very helpful for predicting the CH3OH formation and dissociation cross‐sections for other ion beam projectiles and energies. As astrophysical point of view, the analysis of the predictions reveals the unexpected importance of iron and some other heavy ion constituents of cosmic rays in astrochemistry.

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“…Among the ices studied are water ice and mixtures with carbon dioxide and ammonia (Pilling et al 2010b;Bordalo et al 2013), ammonia (Pilling et al 2010a), methanol (de Barros et al 2011b), and methane ices (de Barros et al 2011a). These studies report on extensive chemical transformation found in the irradiated samples.…”

Section: Introductionmentioning

confidence: 99%

Irradiation of astrophysical ice grains by cosmic-ray ions: a REAX simulation study

Mainitz

Anders

Urbassek

2016

A&A

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Context. The impact of cosmic rays on ice grains delivers considerable energy, inducing chemical reactions and molecule ejection. Aims. We study the effects of cosmic ray impact on ice grains, including shock wave expansion, grain heating, molecule fragmentation, formation of chemical reaction products, sputtering and evaporation. Methods. Molecular-dynamics simulations using the REAX potential allow us to follow the processes occurring in the irradiated ice grain; the mechanical, thermal and chemical consequences are simulated. The ice grain consists of a mixture of water, carbon dioxide, methanol and ammonia. The case of 1 keV/nm energy deposition is studied as an example. Results. The ion track emits a shock wave into the ambient grain. Due to the strong heating, abundant molecule fragmentation is observed; several of the fragments either recombine or form new product molecules. Prompt sputtering from the ion track is followed by evaporation from the surface of the heated grain. We present mass spectra of the chemically transformed species in the grain and in the ejecta.

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Cosmic ray impact on astrophysical ices: laboratory studies on heavy ion irradiation of methane

Cited by 59 publications

References 48 publications

Radiolysis of astrophysical ices by heavy ion irradiation: Destruction cross section measurement

Radiolysis of astrophysical ices by heavy ion irradiation: Destruction cross section measurement

Radiolysis of frozen methanol by heavy cosmic ray and energetic solar particle analogues

Irradiation of astrophysical ice grains by cosmic-ray ions: a REAX simulation study

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