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Project Progress

The interstellar medium contains large dark cold clouds which are full of sub-micrometer interstellar grains. These icy grains are found to contain large amounts of both carbon monoxide and carbon dioxide, however only carbon monoxide is found to be abundant in the gas phase. It is therefore likely that the production of carbon dioxide occurs through the processing of condensed carbon monoxide with irradiation from high energy cosmic rays. It is also likely that more exotic carbon oxides can be produced in this manner, a number of which have been detected for the first time as part of our studies.

We have demonstrated that the high energy cosmic rays are capable of splitting carbon monoxide and molecular oxygen (among other species) into suprathermal carbon and oxygen atoms. The latter are able to react with carbon monoxide to form the carbon dioxide species. Furthermore, the process can continue to form higher carbon oxide species in the series COn (n=3 to 6). It is expected that the same processes may be responsible for generating carbon dioxide in the interstellar medium where carbon monoxide is able to condense onto grains from the gas-phase, along with molecular oxygen, water, and other oxygen-bearing species. As radiation processes these ices, suprathermal oxygen is released and can recombine with the carbon monoxide to form carbon dioxide.