A crossed-molecular beam study on collisional ionization dynamics of acetonitrile and benzene molecules with He*(23S) metastable atoms

Collision-energy/electron-energy resolved two-dimensional Penning ionization electron spectroscopy has been first applied to crossed molecular beams of CH3CN and C6H6 in interaction with a He*(23S) atom. A comparison of two molecular beam conditions, a seeded supersonic jet and an effusive beam, gave considerable differences in the collision energy dependence of partial ionization cross sections (CEDPICS). Since molecules are randomly oriented in the effusive beam, distorted molecular orientations from the spherical distribution in the supersonic jet are concluded to be responsible for the observed difference in CEDPICS.