Query : 2013A&A...559A..49M

2013A&A...559A..49M - Astronomy and Astrophysics, volume 559A, 49-49 (2013/11-1)

CO2 formation on interstellar dust grains: a detailed study of the barrier of the CO+O channel.


Abstract (from CDS):

The formation of carbon dioxide in quiescent regions of molecular clouds has not yet been fully understood, even though CO2 is one of the most abundant species in interstellar ices. CO2 formation is studied via oxidation of CO molecules on cold surfaces under conditions close to those encountered in quiescent molecular clouds. Carbon monoxide and oxygen atoms are codeposited using two differentially pumped beam lines on two different surfaces (amorphous water ice or oxydized graphite) held at given temperatures between 10 and 60K. The products are probed via mass spectroscopy by using the temperature-programmed desorption technique. We show that the reaction CO+O can form carbon dioxide in solid phase with an efficiency that depends on the temperature of the surface. The activation barrier for the reaction, based on modelling results, is estimated to be in the range of 780-475K/kb. Our model also allows us to distinguish the mechanisms (Eley Rideal or Langmuir-Hinshelwood) at play in different temperature regimes. Our results suggest that competition between CO2 formation via CO+O and other surface reactions of O is a key factor in the yields of CO2 obtained experimentally. CO2 can be formed by the CO+O reaction on cold surfaces via processes that mimic carbon dioxide formation in the interstellar medium. Astrophysically, the presence of CO2 in quiescent molecular clouds could be explained by the reaction CO+O occurring on interstellar dust grains.

Abstract Copyright:

Journal keyword(s): publications, bibliography - astrochemistry - atomic processes - ISM: abundances - ISM: atoms - ISM: molecules

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
1 NAME Taurus Complex SFR 04 41.0 +25 52           ~ 4136 0
2 LDN 1689N DNe 16 32 25.96 -24 28 46.2           ~ 114 0
3 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2163 1

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