Resonant contributions to dissociation of H2 by low-energy electron impact

Abstract

A resonance theory of electron-impact vibrational excitation of diatomic molecules is extended to the case where the final vibrational level of the molecule lies in the continuum. The extended theory is applied to resonant dissociation of molecular hydrogen by low-energy electron impact. Theoretical cross sections for dissociation of ground-state H2 via the X 2 Sigma u+ and B 2 Sigma g+ resonances are presented and compared with theoretical cross sections obtained by other authors using non-resonant methods. An important aim of the present work is to study the effect of initial vibrational excitation on the dissociation cross section. It is found that the B 2 Sigma g+ resonance contributes significantly to the total dissociation cross section for all values of vi, for incident energies between 12 eV and 18 eV, while the effect of the X 2 Sigma u+ resonance becomes appreciable only for larger values of vi.