Observation of anisotropic interactions and molecular orbitals of CO upon collision with He*(2³S) atoms by two-dimensional Penning ionization electron spectroscopy

By collision-energy/electron-energy-resolved 2D Penning ionization electron spectroscopy as well as by theoretical calculations of the collisional ionization dynamics, the outer shape of molecular orbitals for ionization to X(²Σ⁺) and A(²Π) states of CO ⁺ was sensitively probed, and the anisotropy of the interaction between He^*(2³S) and CO was determined. Ionization to the B(²Σ⁺) state of CO⁺ was assigned to autoionization from superexcited states by angle-resolved electron spectroscopy and theoretical simulations.