Interaction and dynamics of collisional energy transfers in simple ion-molecule systems

The possible selective pathways for the excitations of vibrational and/or rotational modes of the hydrogen molecule in collisions with two, apparently simple, ionic projectiles (H⁺ and H^-) are studied in detail using quantum-mechanical coupled channels methods and a sudden-type of partial decoupling approximation discussed in the main text. The relevant potential energy surfaces (PES’s) are obtained from the existing literature and an extensive comparison of their features in relation of possible outcomes from inelastic collisions is carried out. The final state-to-state inelastic cross sections, partial integral and differential, are computed and compared with earlier calculations and with the existing experiments. The behaviour of such observables, and their relations with the PES features, help us to shed light on the microscopic mechanisms of collisional energy transfers in some of the simplest ion-molecule and to underline the dynamical effects which stem from their structural differences.