Discrepancy between theory and experiment for nonplanar symmetric (e,2e) momentum profiles ofH2(1Σg+)

The theoretical (e,2e) reaction cross sections for ${\mathrm{H}}_2$ in the plane-wave impulse approximation are calculated by use of the very highly electron correlated ground-state wave function of ${\mathrm{H}}_2$ (this wave function gives 98% of molecular binding energy) and the exact Born-Oppenheimer wave functions of ${\mathrm{H}}_2$ ${\mathrm{}}^{+}$ for the various electronic states. The theoretical value for the n=2 to n=1 cross-section ratio for q≃0.3 a.u. is in good agreement with the experiment, where n is the principal molecular-ion quantum number and q is the recoil momentum. However, the disagreement of 34% for q≃0.7 a.u. remains unresolved. The separate calculated cross sections for transitions to the n=2 final states remain in total disagreement with two sets of experimental data. As a result of the large disagreement, the first-order distorted-wave impulse approximation may not be able to explain such a large discrepancy. It is argued that the disagreement, as large as 10 times in the separate energy spectrum expecially for the peak observed around 30 eV assigned to 2p${\sigma }_u$, may be due to the involvement of an autoionization process of ${\mathrm{H}}_2$. This resembles the energetic proton spectrum reported for ${\mathrm{H}}_2$ by electron impact.