Dissociation of the hydrogen molecule by electron impact

The electron-impact dissociation cross sections of the H₂ molecule have been calculated for the processes leading to H(1s)+H(1s) and to H(1s)+H(2s) by means of the Born-Rudge and Born-Ochkur methods. In addition to direct excitation to the repulsive b³Σᵤ⁺ state for the first process, cross sections are also computed for excitation of the discrete levels of the a³Σg⁺, c³Πᵤ, d³Πᵤ, and e³Σᵤ⁺ states in order to account for cascades. These two mechanisms are found to be of equal importance. The second process is found to proceed mainly through excitation of the B^'¹Σg⁺ state except near the threshold where e³Σᵤ⁺ is an important contributor. The theoretical cross sections are in reasonably good agreement with experimental data for the first process. The cross sections of the second process account for nearly two-thirds of the measured cross sections of H(2s)-atom production by electron impact. The difference is attributed mainly to predissociation and dissociative excitation through the doubly excited states.