Dipole and non-dipole excitation in collisions of low energy electrons with diatomic molecules

Abstract

The authors have measured the rotational envelopes of selected vibrational bands of H₂, D₂, N₂ and CO following excitation of cooled ( approximately 25K) gas beams. The observed broadening in N₂ and CO at low impact energies is attributed to a breakdown of the electric dipole rotational selection rule mod Delta J mod =1. No broadening is observed in H₂ or D₂.