2011 年 45 巻 4 号 p. 213-226
Since the first detection in interstellar medium in 1989, solid CO2 has been found in various lines of sight and regarded as one of the main constituent in icy grain mantles in interstellar clouds. Due to the low efficiency in the formation of CO2 in the gas phase and relatively high abundance of CO in icy grain mantles, it is generally accepted that CO2 forms on the surface of icy grain mantles in interstellar clouds. CO2 formation on/in icy grain mantles has been extensively studied experimentally, with the aid of energetic sources such as UV or cosmic-rays, and also without them. In this review, we summarize experimental results on the formation of CO2 on cold surfaces through energetic and non-energetic processes under the simulative conditions of interstellar molecular clouds.