Simplified model to treat the electron attachment of complex molecules: Application to H2CN and the quest for the CN- formation mechanism

We present a simplified approach to the dissociative electron attachment of polyatomic molecules. A reduced nuclear coordinate driving the dissociative process immediately following the resonance capture is introduced and allows an estimation of the cross section. The model is applied to the H2CN molecule, which is considered as a precursor in the formation of the CN- anion observed in the IRC +10216 carbon star. The computed rate coefficient suggests that the dissociative electron attachment of H2CN may not be an efficient reaction to form CN- in the circumstellar envelope of IRC +10216.