Imitating electron-molecular ion collisions in interstellar space at extremely low temperatures using a storage ring

Dissociative recombination of molecular ions with electrons is a process which plays an important role in many astrophysical environments, such as the gas clouds in the interstellar medium, planetary atmospheres, and comets. It is also a process that has been very reluctant to reveal its secrets to those who attempt to study it, either by experimental or theoretical means. The advent of ion storage-cooler ring technology has provided the experimental atomic and molecular physics community with a very powerful instrument for studies of electron-ion collision processes. In the present paper, dissociative recombination is discussed, and it is shown how cross sections and rate coefficients for astrophysically important molecules like H 3 + and HeH + are obtained. The experiments exploit the possibility to use ion storage as a mean to obtain vibrationally cool molecules. Recent theoretical work is also discussed and related to the new storage ring experiments.