Rotational State-Changing Rate Coefficients Computed for Recently Detected Anionic Cyanopolyines C5N− and C7N− in Collision with He

We report quantum calculations involving the dynamics of energy-transfer processes taking place in Interstellar environments and involving the title molecular species which are part of the anionic molecular chains labeled as cyanopoyines which have very recently been observed in molecule-rich Circumstellar Envelopes. We first carried out new ab initio calculations for the C 7 N − involving its interaction potential with He atoms and therefore obtained state-to-state rotationally inelastic cross sections and rate coefficients over the relevant range of temperatures for both long chains and regarding the state-changing processes which have been very recently observed as radiative transitions for either molecule. The similarities and differences between such species and the comparative efficiencies of collisional rate coefficients with radiative coefficients are analysed and discussed.f Their significance on affecting internal state populations in ISM environments where the title anions are present is discussed.