Vibrational excitation and dissociative attachment in the scattering of electrons by hydrogen molecules

The processes of vibrational excitation and dissociative attachment in the bombardment of hydrogen molecules by electrons of energies up to about 12 eV are discussed. The assumption is made that only the two simplest electron resonances in H 2 - (described in the accompanying paper) need be taken into account. The lower of these resonances, (1sσ g ) 2 (2pσ u ) 2 Σ + u , gives rise to a broad peak, extending from 2 to 6 eV, in the cross section for the excitation of the two lowest excited vibrational states in H 2 . The upper resonance, (1sσ g )(2pσ u ) 2 2 Σ + g , leads mainly to dissociative attachment, with a prominent peak in the cross section extending from about 8 to about 12 eV. The calculated cross sections are in good qualitative and semi-quantitative agreement with experiment. In particular, the shapes and ratios of the peaks in the vibrational cross sections and the shape and isotope effect in the dissociative attachment cross sections around 10 eV are accounted for.