The influence of temperature on the synthesis of molecules on icy grain mantles in dense molecular clouds

Garozzo, M.; Rosa, L.; Kaňuchová, Z.; Ioppolo, Sergio; Baratta, G. A.; Palumbo, M. E.; Strazzulla, G.

doi:10.1051/0004-6361/201015341

Cited by 16 publications

(15 citation statements)

References 55 publications

(65 reference statements)

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“…For instance, solid CO 2 can form from the interaction of energetic photons/ions and pure CO molecules or CO-bearing mixtures. 12,13,[61][62][63][64][65][66][67][68] Solid CO 2 can, however, also be formed through photolysis/radiolysis of amorphous carbon capped with a layer of water or oxygen ice. 15,[69][70][71][72] In space, thermal atom-addition induced chemistry is more dominant in quiescent cold interstellar regions, where newly formed species are protected from radiation to a great extent by dust particles.…”

Section: A Astrochemical Implicationsmentioning

confidence: 99%

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

Ioppolo

Fedoseev

Lamberts

et al. 2013

Review of Scientific Instruments

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A new ultrahigh vacuum experiment is described to study atom and radical addition reactions in interstellar ice analogues for astronomically relevant temperatures. The new setup -SURFace REaction SImulation DEvice (SURFRESIDE 2 ) -allows a systematic investigation of solid state pathways resulting in the formation of molecules of astrophysical interest. The implementation of a double beam line makes it possible to expose deposited ice molecules to different atoms and/or radicals sequentially or at the same time. Special efforts are made to perform experiments under fully controlled laboratory conditions, including precise atom flux determinations, in order to characterize reaction channels quantitatively. In this way, we can compare and combine different surface reaction channels with the aim to unravel the solid state processes at play in space. Results are constrained in situ by means of a Fourier transform infrared spectrometer and a quadrupole mass spectrometer using reflection absorption infrared spectroscopy and temperature programmed desorption, respectively. The performance of the new setup is demonstrated on the example of carbon dioxide formation by comparing the efficiency through two different solid state channels (CO + OH → CO 2 + H and CO + O → CO 2 ) for which different addition products are needed. The potential of SURFRESIDE 2 to study complex molecule formation, including nitrogen containing (prebiotic) compounds, is discussed.

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Section: A Astrochemical Implicationsmentioning

confidence: 99%

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

Ioppolo

Fedoseev

Lamberts

et al. 2013

Review of Scientific Instruments

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“…The distinct processes of ion bombardment and UV irradiation on solids of astrophysical interest are well characterized (e.g., Hagen et al 1979;Brown et al 1982;Moore et al 1983;Strazzulla et al 1983a;Allamandola et al 1988;Baratta et al 1991;Westley et al 1995a;Gerakines et al 1996;Strazzulla et al 2001;Moore et al 2001;Leto & Baratta 2003;Öberg et al 2009;Modica & Palumbo 2010;Garozzo et al 2011). Some investigations on the comparison between the two processes have also been carried out.…”

Section: Introductionmentioning

confidence: 99%

Simultaneous UV- and ion processing of astrophysically relevant ices

Islam

Baratta

Palumbo

2014

A&A

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Context. Interstellar ices are known to be simultaneously processed by both cosmic-ray bombardment and UV photolysis. Our knowledge of the effects of energetic processing on relevant icy samples is mainly based on laboratory investigations. In the past 35 years many experiments have been performed to study these effects separately but, to the best of our knowledge, never simultaneously. Aims. The aim of this work is to study the effects of simultaneous processing of ices by both cosmic rays and UV photons to investigate to what extent the combined effect of ion bombardment and UV photolysis influences the chemical pathways. Methods. We carried out the simultaneous processing of CH 3 OH:N 2 ice held at 16 K by 200 keV H + ions and Lyman-alpha 10.2 eV UV photons. The samples were analyzed by in situ transmission infrared spectroscopy. The un-combined processes of UV irradiation and bombardment by H + ions of CH 3 OH:N 2 ice were also studied. This mixture was chosen because the effects of ion bombardment and UV photolysis on methanol and nitrogen have been extensively studied in previous investigations. This mixture enables one to investigate whether simultaneous processing (a) influences the destruction of original species; (b) influences the formation of new species; or (c) causes synergistic effects since Lyman-alpha photons have a very low efficiency in breaking the dinitrogen bond because N 2 is almost transparent at Lyman-alpha wavelengths. Results. After processing a CH 3 OH:N 2 sample, the intensity of the methanol bands was observed to decrease at the same rate in all cases. After ion bombardment, species such as CO 2 , CO, H 2 CO, CH 4 , N 2 O, HNCO, and OCN − are formed in the ice mixture. After UV photolysis, species such as CO 2 , CO, H 2 CO, and CH 4 are formed, but no N-bearing species are detected. Spectra of ices processed by both UV photons and ions were compared with spectra of ices bombarded only by ions. We find that there are no differences in the band area and profile of N-bearing species for the two types of experiment at the same ion fluence; therefore, the addition of UV irradiation to ion bombardment does not affect the abundance of N-bearing species. The initial formation rate of CH 4 , within the experimental uncertainties, is the same in all cases studied, while the saturation value of CH 4 is higher for UV photolysis than for ion bombardment when they act separately. In the case of simultaneous processing, when the dose (eV/16u) given by UV photons is similar to the dose given during ion bombardment, the saturation value of CH 4 reaches a value intermediate between the value obtained after UV photolysis and ion bombardment separately. Conclusions. Our results confirm that when UV photolysis and ion bombardment act separately, their effects are very similar from a qualitative point of view, while significant quantitative difference may exist. In the case of simultaneous processing we did not detect any synergistic effect, but in some instances the behavior of newly formed spec...

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“…Furthermore, CO 2 ice can be formed upon irradiation of carbon grains covered by a water cap or an oxygen layer (Mennella et al 2004(Mennella et al , 2006Gomis & Strazzulla 2005;Raut et al 2012;Fulvio et al 2012). Recently, Ioppolo et al (2009) and Garozzo et al (2011) quantitatively studied the formation of CO 2 ice upon ion irradiation of interstellar relevant ice mixtures containing C-and O-bearing species at low (12−15 K) and high (40−60 K) temperatures, respectively. Ioppolo et al (2009) used laboratory data of processed ice to fit the CO 2 stretching and bending mode band profiles observed by ISO towards a few high-mass young stellar objects (YSOs).…”

Section: Introductionmentioning

confidence: 99%

“…Ioppolo et al (2009) used laboratory data of processed ice to fit the CO 2 stretching and bending mode band profiles observed by ISO towards a few high-mass young stellar objects (YSOs). Here we compare new laboratory data, together with those presented in Ioppolo et al (2009) and Garozzo et al (2011), with a wider sample of sources in low-mass star forming regions with the intent of constraining the contribution of energetic processing to the formation of solid CO 2 in space at different stages of star forming regions (see Tables 4, 5 and the discussion in Sect. 3.3).…”

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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The influence of temperature on the synthesis of molecules on icy grain mantles in dense molecular clouds

Cited by 16 publications

References 55 publications

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

Simultaneous UV- and ion processing of astrophysically relevant ices

Solid CO₂in low-mass young stellar objects

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The influence of temperature on the synthesis of molecules on icy grain mantles in dense molecular clouds

Cited by 16 publications

References 55 publications

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

SURFRESIDE2: An ultrahigh vacuum system for the investigation of surface reaction routes of interstellar interest

Simultaneous UV- and ion processing of astrophysically relevant ices

Solid CO2in low-mass young stellar objects

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Solid CO₂in low-mass young stellar objects