skip to main content
Idioma:

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, J. Á. ; Rogero, C. ; Atienza, C. ; Puertas, S. ; Sobrado, J. M. ; Torres-Redondo, J.

Astronomy and astrophysics (Berlin), 2010-11, Vol.522, p.A108 [Periódico revisado por pares]

Les Ulis: EDP Sciences

Texto completo disponível

Citações Citado por
  • Título:
    New results on thermal and photodesorption of CO ice using the novel InterStellar Astrochemistry Chamber (ISAC)
  • Autor: Muñoz Caro, G. M. ; Jiménez-Escobar, A. ; Martín-Gago, J. Á. ; Rogero, C. ; Atienza, C. ; Puertas, S. ; Sobrado, J. M. ; Torres-Redondo, J.
  • Assuntos: Astrochemistry ; Astronomy ; Carbon monoxide ; Clouds ; Density ; Desorption ; Earth, ocean, space ; Exact sciences and technology ; infrared: ISM ; Interstellar ; Irradiation ; ISM: clouds ; ISM: molecules ; methods: laboratory ; molecular processes ; Photons ; techniques: spectroscopic
  • É parte de: Astronomy and astrophysics (Berlin), 2010-11, Vol.522, p.A108
  • Notas: publisher-ID:aa12462-09
    e-mail: munozcg@inta.es
    bibcode:2010A%26A...522A.108M
    istex:566C9A00A0F315293CFA08AC8ADB5A76FA321939
    ark:/67375/80W-HNQDW77N-P
    dkey:10.1051/0004-6361/200912462
    ObjectType-Article-1
    SourceType-Scholarly Journals-1
    ObjectType-Feature-2
    content type line 23
  • Descrição: 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.
  • Editor: Les Ulis: EDP Sciences
  • Idioma: Inglês
Links
Voltar para lista de resultados
Ir para página anteriorAnterior Resultado  2 AvançarIr para próxima página

  • Realização: ABCD-USP USP   Logos de Redes Sociais: Freepik

Buscando em bases de dados remotas. Favor aguardar.