Strong molecular alignment dependence of H ₂ electron impact ionization dynamics

Low-energy (E ₀=54eV) electron impact single ionization of molecular hydrogen (H ₂) has been investigated as a function of molecular alignment in order to benchmark recent theoretical predictions. In contrast to any previous work, we observe distinct alignment dependence of the (e,2e) cross sections in the perpendicular plane in good overall agreement with results from time-dependent close-coupling calculations. The cross section behavior can be consistently explained by a rescattering of the ejected electron in the molecular potential resulting in an effective focusing along the molecular axis.