Threshold peaks in the vibrational excitation of molecules by electron impact: a time-dependent view

Resonance and threshold effects in low-energy electronmolecule collisions are analyzed in a time-dependent picture. Time-dependent wave packets reflecting the non-Markovian open-system dynamics of electron-molecule collision complexes are explicitly generated for two representative models of pure s-wave scattering and dipole-modified s-wave scattering, respectively. The numerical results demonstrate the relevance of the adiabatic potential-energy curves of resonances, virtual states and bound states for a qualitative understanding of the dynamics and lucidly reveal the existence of nonadiabatic processes in such systems.