Formation of H3- by radiative association of H2 and H- in the interstellar medium
Abstract
We develop the theory of radiative association of an atom and a diatomic molecule within a close-coupling framework. We apply it to the formation of H3- after the low energy collision (below 0.5 eV) of H2 with H-. Using recently obtained potential energy and permanent dipole moment surfaces of H3-, we calculate the lowest rovibrational levels of the H3- electronic ground state, and the cross section for the formation of H3- by radiative association between H- and ortho- and para-H2. We discuss the possibility for the H3- ion to be formed and observed in the cold and dense interstellar medium in an environment with a high ionization rate. Such an observation would be a probe for the presence of H- in the interstellar medium.
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