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.