Stereodynamics of electron-induced dissociative ionization of N₂ studied by (: E, e +ion) spectroscopy

We report an (e, e+ion) spectroscopy study on electron-induced dissociative ionization of N₂. Vector correlation between the scattered electron and N⁺ ion has been measured for inner-valence ionization of N₂ at an incident electron energy of 1.4 keV and scattering angles of 2.2°, 4.2°, and 8.2°. By analyzing the experimental data, partial ion yield spectra have been obtained for transitions to the C ²Σ+u, F ²Σ+g, and 2σ-1g ion states, showing that the individual transitions depend on the momentum transferred to the target, K, in different ways. The molecular-orientation dependence of the ionization cross section has subsequently been examined for the F ²Σ+g ionization. To account for the angular anisotropy of the scattering cross section, a compact analytical form has been developed. It is elucidated that for small K the F ²Σ+g ionization preferentially takes place when the molecule has its axis aligned parallel to the momentum transfer vector due to σ_u shape resonance, while the angular distribution drastically changes with K, indicating strong influences of non-dipole interaction on the ionization dynamics. It has been shown that the present method provides a powerful means to explore K-dependent stereodynamics in electron-induced dissociative ionization of molecules.