Collision-energy-resolved angular distribution of Penning electrons for N₂-He^*(2³S)

The collision-energy-resolved angular distributions of Penning electrons for individual ionic state of N₂-He^*(2³S) were measured. The angular distributions showed increasing intensity in the backward (rebounding) directions with respect to initial He^*(2³S) beam vector because Penning ionization occurs with a collision against repulsive interaction wall followed by the electron emission from 2s orbital of He^*. We also analyzed internal angular distribution by means of fitting parameters using classical trajectory calculations for N₂-He^*(2³S) on the modified interaction potential. These internal angular distributions suggested the electron emission from 2s orbital of He^* and they depended on collision energy and electron kinetic energy.