New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)
[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 irra...
| Autores: | , , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión publicada |
| Fecha de publicación: | 2010 |
| País: | España |
| Institución: | Consejo Superior de Investigaciones Científicas (CSIC) |
| Repositorio: | DIGITAL.CSIC. Repositorio Institucional del CSIC |
| OAI Identifier: | oai:digital.csic.es:10261/344271 |
| Acceso en línea: | http://hdl.handle.net/10261/344271 |
| Access Level: | acceso abierto |
| Palabra clave: | ISM: clouds ISM: molecules Molecular processes Methods: laboratory Infrared: ISM Techniques: spectroscopic |
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New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)Muñoz Caro, G.M.Jiménez-Escobar, A.Martín-Gago, José A.Rogero, CeliaAtienza, C.Puertas, S.Sobrado, Jesús ManuelTorres-Redondo, JosefinaISM: cloudsISM: moleculesMolecular processesMethods: laboratoryInfrared: ISMTechniques: spectroscopic[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 H2 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 × 104 cm-3. For the same density of a cloud, 3 × 104 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.A.J.E. is supported by a research training grant from INTA. G.M.M.C. was financed by a Ramón y Cajal research contract from the MCYT in Spain. This work was supported by project AYA2008-06374 funded by Spanish MICINN.Peer reviewedEDP SciencesMinisterio de Ciencia y Tecnología (España)Ministerio de Ciencia e Innovación (España)Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72]2024202420102024info:eu-repo/semantics/articlehttp://purl.org/coar/resource_type/c_6501Publisher's versioninfo:eu-repo/semantics/publishedVersionapplication/pdfhttp://hdl.handle.net/10261/344271reponame:DIGITAL.CSIC. Repositorio Institucional del CSICinstname:Consejo Superior de Investigaciones Científicas (CSIC)Inglés#PLACEHOLDER_PARENT_METADATA_VALUE#info:eu-repo/grantAgreement/MICINN//AYA2008-06374https://doi.org/10.1051/0004-6361/200912462Síinfo:eu-repo/semantics/openAccessoai:digital.csic.es:10261/3442712026-05-22T06:33:51Z |
| dc.title.none.fl_str_mv |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| title |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| spellingShingle |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) Muñoz Caro, G.M. ISM: clouds ISM: molecules Molecular processes Methods: laboratory Infrared: ISM Techniques: spectroscopic |
| title_short |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| title_full |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| title_fullStr |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| title_full_unstemmed |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| title_sort |
New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC) |
| dc.creator.none.fl_str_mv |
Muñoz Caro, G.M. Jiménez-Escobar, A. Martín-Gago, José A. Rogero, Celia Atienza, C. Puertas, S. Sobrado, Jesús Manuel Torres-Redondo, Josefina |
| author |
Muñoz Caro, G.M. |
| author_facet |
Muñoz Caro, G.M. Jiménez-Escobar, A. Martín-Gago, José A. Rogero, Celia Atienza, C. Puertas, S. Sobrado, Jesús Manuel Torres-Redondo, Josefina |
| author_role |
author |
| author2 |
Jiménez-Escobar, A. Martín-Gago, José A. Rogero, Celia Atienza, C. Puertas, S. Sobrado, Jesús Manuel Torres-Redondo, Josefina |
| author2_role |
author author author author author author author |
| dc.contributor.none.fl_str_mv |
Ministerio de Ciencia y Tecnología (España) Ministerio de Ciencia e Innovación (España) Consejo Superior de Investigaciones Científicas [https://ror.org/02gfc7t72] |
| dc.subject.none.fl_str_mv |
ISM: clouds ISM: molecules Molecular processes Methods: laboratory Infrared: ISM Techniques: spectroscopic |
| topic |
ISM: clouds ISM: molecules Molecular processes Methods: laboratory Infrared: ISM Techniques: spectroscopic |
| description |
[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 H2 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 × 104 cm-3. For the same density of a cloud, 3 × 104 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. |
| publishDate |
2010 |
| dc.date.none.fl_str_mv |
2010 2024 2024 2024 |
| dc.type.none.fl_str_mv |
info:eu-repo/semantics/article http://purl.org/coar/resource_type/c_6501 Publisher's version info:eu-repo/semantics/publishedVersion |
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article |
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publishedVersion |
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http://hdl.handle.net/10261/344271 |
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http://hdl.handle.net/10261/344271 |
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Inglés |
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Inglés |
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#PLACEHOLDER_PARENT_METADATA_VALUE# info:eu-repo/grantAgreement/MICINN//AYA2008-06374 https://doi.org/10.1051/0004-6361/200912462 Sí |
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EDP Sciences |
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EDP Sciences |
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