Measurements of polyatomic molecule formation on an icy grain analog using fast atoms

Madzunkov, S.; Shortt, Brian; MacAskill, J. A.; Darrach, M. R.; Chutjian, A.

doi:10.1103/physreva.73.020901

Cited by 27 publications

(29 citation statements)

References 21 publications

(2 reference statements)

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“…TPD experiments have been performed to study the CO+O route by using thermal O atoms below 160 K [115]) and energetic O atoms [116]. In the first case, this reaction was found to proceed only in water pores under a water ice cap and upon heating, while in the second case the energetic O atoms allowed the reaction to proceed.…”

Section: Co+oh Vs Co+omentioning

confidence: 99%

“…Therefore, this route is still to be investigated experimentally, but the reaction CO+O has been extensively studied by different groups [115,116,122]. (Fig.…”

Section: Co+oh Vs Co+omentioning

confidence: 99%

“…mainly following CO+OH and CO+O [115][116][117][118][119][120][121][122][123][124][125] The central part of the SURFace REaction Simulation Device (Figure 2) is an UHV chamber (10 -10 -10 -11 mbar) onto which two atom beam lines are mounted that aim at an optically flat gold coated cupper substrate (2.5 x 2.5 cm 2 ) placed in the centre of the main chamber, and mounted on the tip of a cold-head with temperatures accessible between 12 and 300 K using resistive heating. Ices are grown using two all metal high-vacuum stainless steel dosing lines, allowing different gasses to be deposited separately or simultaneously onto the gold substrate.…”

Section: State-of-the-artmentioning

confidence: 99%

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Atom addition reactions in interstellar ice analogues

Linnartz

Ioppolo

Fedoseev

2015

International Reviews in Physical Chemistry

161

142

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It was in 'The Magellanic Cloud' (1955) -a science fiction novel by Stanislaw Lem -that engineers traveling to another star noticed that their spacecraft for unknown reasons overheated. The cause had to be outside the spaceship, but obviously there was only emptiness, at least compared to terrestrial conditions. The space between the stars, the interstellar medium, however, is not completely empty and at the high speed of the spacecraft the cross-section with impacting particles, even from such a dilute environment, was found to be sufficient to cause an overheating. Today, 60 years later, the interstellar medium has been studied in detail by astronomical observations, reproduced in dedicated laboratory experiments and simulated by complex astrochemical models. The space between the stars is, indeed, far from empty; it comprises gas, dust and ice and the molecules detected so far are both small (diatomics) and large (long carbon chains, PAHs and fullerenes), stable and reactive (radicals, ions, and excited molecules) evidencing an exotic and fascinating chemistry, taking place at low densities, low temperatures and experiencing intense radiation fields.Astrochemists explain the observed chemical complexity in space -so far 185 different molecules (not including isotopologues) have been identified -as the cumulative outcome of P a g e | 2 reactions in the gas phase and on icy dust grains. Gas phase models explain the observed abundances of a substantial part of the observed species, but fail to explain the number densities for stable molecules, as simple as water, methanol or acetonitrile -one of the most promising precursor species for the simplest amino acid glycine -as well as larger compounds such as glycolaldehyde, dimethylether and ethylene glycol. Evidence has been found that these and other complex species, including organic ones, form on icy dust grains that act as catalytic sites for molecule formation. It is here where particles 'accrete, meet, and greet' (i.e., freeze out, diffuse and react) upon energetic and non-energetic processing, such as irradiation by vacuum UV light, interaction with impacting particles (atoms, electrons and cosmic rays) or heating.This review paper summarizes the state-of-the-art in laboratory based interstellar ice chemistry. The focus is on atom addition reactions, illustrating how water, carbon dioxide and methanol can form in the solid state at astronomically relevant temperatures, and also the formation of more complex species such as hydroxylamine, an important prebiotic molecule, and glycolaldehyde, the smallest sugar, is discussed. These reactions are particularly relevant during the 'dark' ages of star and planet formation, i.e., when the role of UV light is restricted.A quantitative characterization of such processes is only possible through dedicated laboratory studies, i.e., under full control of a large set of parameters such as temperature, atom-flux, and ice morphology. The resulting numbers, physical and chemical constants, e.g., barrier heights, react...

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Section: Co+oh Vs Co+omentioning

confidence: 99%

“…Therefore, this route is still to be investigated experimentally, but the reaction CO+O has been extensively studied by different groups [115,116,122]. (Fig.…”

Section: Co+oh Vs Co+omentioning

confidence: 99%

Section: State-of-the-artmentioning

confidence: 99%

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Atom addition reactions in interstellar ice analogues

Linnartz

Ioppolo

Fedoseev

2015

International Reviews in Physical Chemistry

161

142

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“…Recently, Goumans & Andersson (2010) used harmonic quantum transition state theory to prove that, while quantum mechanical tunneling through the activation barrier increases the classical reaction rate for reaction 1 at low temperatures (10−20 K), the onset of tunneling is at temperatures that are too low for the reaction to efficiently contribute to CO 2 formation in quiescent cold regions. Reaction 1 has been experimentally investigated by temperatureprogramed desorption experiments using thermal O atoms below 160 K (Roser et al 2001) and by energetic O atoms (Madzunkov et al 2006). In the first case, reaction 1 was found to proceed only in water pores under a water ice cap and upon heating, while in the second case the energetic O atoms allowed the reaction to proceed.…”

Section: Introductionmentioning

confidence: 99%

Solid CO₂in low-mass young stellar objects

Ioppolo

Sangiorgio

Baratta

et al. 2013

A&A

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Context. Solid interstellar CO 2 is an abundant component of ice dust mantles. Its ubiquity towards quiescent molecular clouds, as well as protostellar envelopes, has recently been confirmed by the IRS (InfraRed Spectrograph) aboard the Spitzer Space Telescope. Although it has been shown that CO 2 cannot be efficiently formed in the gas phase, the CO 2 surface formation pathway is still unclear. To date several CO 2 surface formation mechanisms induced by energetic (e.g., UV photolysis and cosmic ray irradiation) and nonenergetic (e.g., cold atom addition) input have been proposed. Aims. Our aim is to investigate the contribution of cosmic ray irradiation to the formation of CO 2 in different regions of the interstellar medium (ISM). To achieve this goal we compared quantitatively laboratory data with the CO 2 bending mode band profile observed towards several young stellar objects (YSOs) and a field star by the Spitzer Space Telescope. Methods. All the experiments presented here were performed at the Laboratory for Experimental Astrophysics in Catania (Italy). The interstellar relevant samples were all irradiated with fast ions (30−200 keV) and subsequently annealed in a stainless steel high vacuum chamber (P < 10 −7 mbar). Chemical and structural modifications of the ice samples were monitored by means of infrared spectroscopy. Laboratory spectra were then used to fit some thirty observational spectra.Results. A qualitative analysis shows that a good fit can be obtained with a minimum of two components. The choice of the laboratory components is based on the chemical-physical condition of each source. A quantitative analysis of the sources with known visual extinction (A V ) and methanol abundances highlights that the solid carbon dioxide can be efficiently and abundantly formed after ion irradiation of interstellar ices in all the selected YSOs in a time compatible with cloud lifetimes (3 × 10 7 years). Only in the case of field stars can the expected CO 2 column density formed upon energetic input not explain the observed abundances. This result, to be confirmed along the line of sight to different quiescent clouds, gives an indirect indication that CO 2 can also be formed in an early cloud stage through surface reactions induced by non-energetic mechanisms. In a later stage, when ices are exposed to higher UV and cosmic ray doses, the CO 2 total abundance is strongly affected by energetic formation mechanisms. Conclusions. Our results indicate that energetic processing of icy grain mantles significantly contribute to the formation of solid phase interstellar CO 2 .

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“…For instance, solid CO 2 can form in the impact of energetic photons and particles of condensed pure CO or mixtures of CO with additional species such as H 2 O or O 2 (e.g., Moore et al 1991;Gerakines et al 1996;Ehrenfreund et al 1997;Palumbo et al 1998;Satorre et al 2000;Watanabe & Kouchi 2002;Loeffler et al 2005;Ioppolo et al 2009). Moreover, radiationless processes can produce CO 2 in chemical reactions, such as oxidation of CO by hot (Madzunkov et al 2006) or cold (Roser et al 2001; oxygen. Another example of surface chemical reactions is CO 2 formation when mixed films of CO and O 2 are exposed to H atoms (Ioppolo et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Photosynthesis of Carbon Dioxide From Carbon Surfaces Coated With Oxygen: Implications for Interstellar Molecular Clouds and the Outer Solar System

Fulvio

Raut

Baragiola

2012

ApJ

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We investigate via infrared spectroscopy the synthesis of CO 2 by ultraviolet irradiation (6.41 eV) of amorphous carbon covered with solid O 2 at 21 K. Oxidation occurs at the O 2 -carbon interface promoted by photon excitation or dissociation of O 2 molecules. The CO 2 production is linear with photon fluence with a yield of 3.3 ± 0.3 × 10 −5 CO 2 photon −1 ; the yield does not decrease at high fluences (at least up to 2 × 10 19 photons cm −2 ) since CO 2 is not photodissociated at this photon energy. Replacing oxygen with water ice did not produce CO 2 since H 2 O does not dissociate at this photon energy. The CO 2 synthesis process discussed in this Letter does not require H 2 O or CO and may be important in cold astrophysical environments where O 2 could be locally segregated on carbonaceous grains, such as in molecular clouds and icy objects in the outer solar system.

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Measurements of polyatomic molecule formation on an icy grain analog using fast atoms

Cited by 27 publications

References 21 publications

Atom addition reactions in interstellar ice analogues

Atom addition reactions in interstellar ice analogues

Solid CO₂in low-mass young stellar objects

Photosynthesis of Carbon Dioxide From Carbon Surfaces Coated With Oxygen: Implications for Interstellar Molecular Clouds and the Outer Solar System

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Measurements of polyatomic molecule formation on an icy grain analog using fast atoms

Cited by 27 publications

References 21 publications

Atom addition reactions in interstellar ice analogues

Atom addition reactions in interstellar ice analogues

Solid CO2in low-mass young stellar objects

Photosynthesis of Carbon Dioxide From Carbon Surfaces Coated With Oxygen: Implications for Interstellar Molecular Clouds and the Outer Solar System

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Product

Resources

About

Solid CO₂in low-mass young stellar objects