Dissociation cross section of H{sub 2} by electron impact

According to the Revised Bethe theory, the dissociation cross sections of H{sub 2} by electron impact are accurately computed by using the best wave functions of excited states. The calculated cross sections due to the dissociation into H(1s) and H(2s) are shown for comparison with the experimental data reported elsewhere. The experimental data are underestimated by the theoretical values. This that the dissociation due to the autoionization is very important and is not negligibly small at the incident electron energies greater than 50 eV. The calculated isotope effect due to the dissociation is too small to compare with the experimental data. The large isotope effect is also due to the dissociation via the autoionization.