Two-dimensional Penning ionization electron spectroscopy of CO/He*(23S)

Two-dimensional Penning ionization electron spectrum (2D-PIES) of CO by collision with He*(2(3)S) was observed. Collision energy dependence of partial ionization cross-sections was reproduced theoretically by trajectory calculation with anisotropic potential energy surface. In order to obtain the potential energy surfaces for exit channel, ionic ground and excited states were calculated for CO+-He. By adding up the electron transition probabilities for the specific electron energy calculated by the difference between potential energies for the entrance and the exit channels at each trajectory step, the collision-energy-resolved Penning ionization electron spectrum (CERPIES) was obtained. The CERPIESs at various collision energies were then converted into calculated 2D-PIES. (C) 2001 Elsevier Science B.V. All rights reserved.