Ion irradiation of astrophysical ices

Palumbo, M. E.; Baratta, G. A.; Fulvio, D.; Garozzo, M.; Gomis, O.; Leto, G.; Spinella, F.; Strazzulla, G.

doi:10.1088/1742-6596/101/1/012002

Cited by 30 publications

(15 citation statements)

References 48 publications

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“…These results simulate the effects produced by high-energy heavy cosmic-ray ions in interstellar grain mantles [23,28]. The CO radiolysis effects induced by nickel ions, protons (200 keV [29,30]; 800 keV [24]); photons (10.2 eV [24,29,31,32]), and electrons (5 keV [33]) are quite similar.…”

Section: Co and Co 2 Experimentssupporting

confidence: 54%

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: Co and Co 2 Experimentssupporting

confidence: 54%

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 resulting residue was shown to consist of more complex organic compounds (e.g., Hagen et al 1979;Allamandola et al 1988;Gerakines et al 1995;Hudson and Moore 2000;Strazzulla and Palumbo 2001;Mennella et al 2004Mennella et al , 2006Bennett and Kaiser 2007;Palumbo et al 2008). The experimental results using this approach have been compared to interstellar ices generally in a more qualitative than quantitative way.…”

Section: Bottom-up Versus Top-down Approachmentioning

confidence: 99%

Surface formation routes of interstellar molecules: hydrogenation reactions in simple ices

Ioppolo

Cuppen

Linnartz

2011

Rend. Fis. Acc. Lincei

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It has been a long standing problem in astrochemistry to explain how molecules can form in a highly dilute environment such as the interstellar medium. In recent years it has become clear that not only ion/radical-molecule gas-phase reactions, but also solid state reactions on icy dust grains play an important role in the formation of new species. In order to investigate the underlying processes, laboratory based experiments are needed to simulate surface reactions induced by photon (UV) processing or particle (atom, cosmic ray, electron) bombardment of interstellar ice analogs. Here, the latest research performed on SURFace REaction SImulation DEvice (SURFRESIDE), one of the ultra-high vacuum setups in the Sackler Laboratory for Astrophysics in Leiden is reviewed. The focus is on hydrogenation, i.e., H-atom addition reactions in interstellar ice analogs for astronomically relevant temperatures. We discuss how molecules form when CO and O 2 containing ices are exposed to thermal hydrogen atoms under fully controlled experimental conditions. Surface formation schemes for interstellar relevant species, such as solid methanol, water, and carbon dioxide are investigated and chemical links between molecular species in space are discussed.

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“…Numerous publications have reported ion bombardment experiments of interstellar ice analogues (e.g. Palumbo et al 2008;Hudson & Moore 2001). However, these experiments are mainly performed at ion energies of 1 MeV or below, most of them involving irradiations with protons or light elements.…”

Section: Introductionmentioning

confidence: 99%

Swift heavy ion irradiation of water ice from MeV to GeV energies

Dartois

Ding

Barros

et al. 2013

A&A

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Context. Cosmic ray ion irradiation affects the chemical composition of and triggers physical changes in interstellar ice mantles in space. One of the primary structural changes induced is the loss of porosity, and the mantles evolve toward a more compact amorphous state. Previously, ice compaction was monitored at low to moderate ion energies. The existence of a compaction threshold in stopping power has been suggested. Aims. In this article we experimentally study the effect of heavy ion irradiation at energies closer to true cosmic rays. This minimises extrapolation and allows a regime where electronic interaction always dominates to be explored, providing the ice compaction cross section over a wide range of electronic stopping power. Methods. High-energy ion irradiations provided by the GANIL accelerator, from the MeV up to the GeV range, are combined with in-situ infrared spectroscopy monitoring of ice mantles. We follow the IR spectral evolution of the ice as a function of increasing fluence (induced compaction of the initial microporous amorphous ice into a more compact amorphous phase). We use the number of OH dangling bonds of the water molecule, i.e. pending OH bonds not engaged in a hydrogen bond in the initially porous ice structure as a probe of the phase transition. These high-energy experiments are combined with lower energy experiments using light ions (H, He) from other facilities in Catania, Italy, and Washington, USA. Results. We evaluated the cross section for the disappearance of OH dangling bonds as a function of electronic stopping power. A cross-section law in a large energy range that includes data from different ice deposition setups is established. The relevant phase structuring time scale for the ice network is compared to interstellar chemical time scales using an astrophysical model. Conclusions. The presence of a threshold in compaction at low stopping power suggested in some previous works seems not to be confirmed for the high-energy cosmic rays encountered in interstellar space. Ice mantle porosity or pending bonds monitored by the OH dangling bonds is removed efficiently by cosmic rays. As a consequence, this considerably reduces the specific surface area available for surface chemical reactions.

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Ion irradiation of astrophysical ices

Cited by 30 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

Surface formation routes of interstellar molecules: hydrogenation reactions in simple ices

Swift heavy ion irradiation of water ice from MeV to GeV energies

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