Resonant electron attachment to polar aromatic molecules: consequences for their chemistry in the interstellar medium

In this paper we present and discuss the results obtained from ab-initio quantum scattering calculations of the response from neutral aromatic species like C6H5 (phenyl) and C6H4 (benzyne, ortho isomer) to low-energy electron collisions. Our main purpose is to investigate the possible mechanisms that can lead to the final formation of their stable negative ions under astrophysical conditions, by linking low-lying metastable anionic states to bound anionic states. Quantum chemical calculations were also employed to confirm the features of the metastable resonant states found by the scattering calculations, while the role of the permanent dipole moments of both systems on the scattering behaviour for near-threshold electrons is also analysed in some detail. The possible energy redistribution paths for stabilizing both anionic species under ISM conditions are discussed in the conclusions.