Carbon Suboxide in Astrophysical Ice Analogs

Gerakines, Perry A.; Moore, M. H.

doi:10.1006/icar.2001.6711

Cited by 75 publications

(88 citation statements)

References 31 publications

(39 reference statements)

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“…The infrared bands of photoproducts were only clearly detected in the thick CO ice photodesorption experiments reported here. They are associated to CO 2 , C 3 O, and C 3 O 2 , which were previously detected in CO irradiation experiments , and references therein; Gerakines & Moore 2001;Loeffler et al 2005). These photoproducts account for less than 5% of the CO band decrease in our experiments, CO 2 ≤ 3%.…”

Section: Photodesorption Of Thick Co Ice At 8 K and 15 Ksupporting

confidence: 75%

New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)

Muñoz

Jiménez-Escobar

Martín‐Gago

et al. 2010

A&A

135

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Aims. We present the novel InterStellar Astrochemistry Chamber (ISAC), designed for studying solids (ice mantles, organics, and silicates) in interstellar and circumstellar environments: characterizing their physico-chemical properties and monitoring their evolution as caused by (i) vacuum-UV irradiation; (ii) cosmic ray irradiation; and (iii) thermal processing. Experimental study of thermal and photodesorption of the CO ice reported here simulates the freeze-out and desorption of CO on grains, providing new information on these processes. Methods. ISAC is an UHV set-up, with base pressure down to P = 2.5 × 10 −11 mbar, where an ice layer is deposited at 7 K and can be UV-irradiated. The evolution of the solid sample was monitored by in situ transmittance FTIR spectroscopy, while the volatile species were monitored by QMS. Results. The UHV conditions of ISAC allow experiments under extremely clean conditions. Transmittance FTIR spectroscopy coupled to QMS proved to be ideal for in situ monitoring of ice processes that include radiation and thermal annealing. Thermal desorption of CO starting at 15 K, induced by the release of H 2 from the CO ice, was observed. We measured the photodesorption yield of CO ice per incident photon at 7, 8, and 15 K, respectively yielding 6.4 ± 0.5 × 10 −2 , 5.4 ± 0.5 × 10 −2 , and 3.5 ± 0.5 × 10 −2 CO molecules photon (7.3-10.5 eV) −1 . Our value of the photodesorption yield of CO ice at 15 K is about one order of magnitude higher than the previous estimate. We confirmed that the photodesorption yield is constant during irradiation and independent of the ice thickness. Only below ∼5 monolayers ice thickness the photodesorption rate decreases, which suggests that only the UV photons absorbed in the top 5 monolayers led to photodesorption. The measured CO photodesorption quantum yield at 7 K per absorbed photon in the top 5 monolayers is 3.4 molecules photon −1 . Conclusions. Experimental values were used as input for a simple model of a quiescent cloud interior. Photodesorption seems to explain the observations of CO in the gas phase for densities below 3-7 ×10 4 cm −3 . For the same density of a cloud, 3 × 10 4 cm −3 , thermal desorption of CO is not triggered until T = 14.5 K. This has important implications for CO ice mantle build up in dark clouds.

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Section: Photodesorption Of Thick Co Ice At 8 K and 15 Ksupporting

confidence: 75%

New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)

Muñoz

Jiménez-Escobar

Martín‐Gago

et al. 2010

A&A

135

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“…The band at 1785 and 1762 cm −1 is due to the C=O double bond stretch and is most probably related to the new C n O species. As compared to Gerakines & Moore (2001), the residue in Figure 7 is a "compromise" between those obtained with proton irradiation of C 3 O 2 and CO ices. In particular, X-ray irradiation of CO ice produces a residue much more abundant in species with C=C=O bonds (peak at 2155 cm −1 ) than the proton Table 2. 4.…”

Section: Products Of the Irradiationmentioning

confidence: 95%

“…Laboratory studies of the evolution of interstellar ice analogs under the effect of photon irradiation and ionized particles have greatly contributed to our understanding of the chemistry of complex organic molecules synthesized in space. In particular, the chemical modifications of CO ices, both pure or in mixture, have been studied under the effect of vacuum (Gerakines et al 1996;Gerakines & Moore 2001;Cottin et al 2003;Loeffler et al 2005;Chen et al 2014) and extreme-ultraviolet radiation (Wu et al 2005), ions (Gerakines & Moore 2001;Trottier & Brooks 2004;Loeffler et al 2005;Domaracka et al 2010) and electrons (Jamieson et al 2006). Muñoz Caro et al (2010) measured the photodesorption yield of CO ice under ultraviolet irradiation, finding the release yield at 15 K to be about one order of magnitude higher than previous estimates.…”

Section: Introductionmentioning

confidence: 99%

Chemical Evolution of a Co Ice Induced by Soft X-Rays

Ciaravella

Chen

Cecchi‐Pestellini

et al. 2016

ApJ

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We irradiated a pure carbon monoxide ice with soft X-rays of energies up to 1.2 keV. The experiments were performed using the spherical grating monochromator beamline at the National Synchrotron Radiation Research Center in Taiwan, exploiting both monochromatic (at 0.3 and 0.55 keV) and broader energy (0.25-1.2 keV) fluxes. The infrared spectra of the irradiated ices showed the formation of a number of products such as polycarbon monoand dioxides C n O m , and chains containing up to 10 carbon atoms. While a gentle increase in the energy absorbed by the ice sample is reflected by an increase in the column densities of newly born species, such correlation breaks down at very high fluxes. In this regime the production yield falls down sharply by about a factor of 100. The refractory residue obtained in the broad energy irradiation is a "compromise" between those obtained with proton irradiation of C 3 O 2 and CO ices in previous experiments. Finally, we discuss the possible implications for space chemistry

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“…This topic has been researched recently by Gerakines & Moore (2001), who reported that Lyman-α is 3.5 times more efficient than 800 keV protons in synthesizing CO 2 on virgin CO per unit incident energy. This is surprising for several reasons.…”

Section: Introductionmentioning

confidence: 99%

CO$\mathsf{_{2}}$ synthesis in solid CO by Lyman-α photons and 200 keV protons

Loeffler

Baratta²,

Palumbo³

et al. 2005

A&A

137

150

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Abstract.We have studied the synthesis of carbon dioxide from solid carbon monoxide at 16 K induced by photolysis with Lyman-α photons and by irradiation with 200 keV protons to quantitatively compare the effects of photolysis and ion irradiation on CO ice and to determine the importance of these processes in interstellar ice grains. The CO and CO 2 concentrations during irradiation of an initially pure CO film evolve with fluence to a saturation value, a behaviour that is explained by a two-state model. Our results indicate that the initial CO 2 production rates for both radiation processes are similar when normalized to the absorbed energy and that the solid CO 2 abundance observed in the interstellar ices cannot be explained only by radiolysis and photolysis of pure solid CO.

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Carbon Suboxide in Astrophysical Ice Analogs

Cited by 75 publications

References 31 publications

New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)

New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)

Chemical Evolution of a Co Ice Induced by Soft X-Rays

CO$\mathsf{_{2}}$ synthesis in solid CO by Lyman-α photons and 200 keV protons

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