Trajectory calculations of two-dimensional Penning ionization electron spectra of N₂ in collision with metastable He^* 2³S atoms

Ionization cross-sections of N₂ in collision with He^*2³S as functions of the collision energy and the ejected electron kinetic energy (two-dimensional Penning ionization electron spectra, 2D-PIES) have been evaluated by trajectory calculations based on quantum chemical potential surfaces of both entrance and exit channels as well as on the transition widths for producing X, A, and B states of N₂⁺. The present approach using a Li atom for He^* and an overlap approximation for Γ has given theoretical 2D-PIES in good agreement with the observation and a promise for its application to the study of dynamics in collisional ionization involving highly anisotropic target systems.