Two-dimensional Penning ionization electron spectroscopy of carbon disulfide: spectral assignments and anisotropic interactions with a He*(23S) metastable atom

Collision-energy-resolved Penning ionization electron spectra are measured for carbon disulfide (CS2) by collision with a He*(23S) metastable atom. Assignments in Penning ionization electron spectrum are made on the basis of collision energy dependence of the partial ionization cross sections (CEDPICS). CEDPICS for the X2Πg, A2Πu, B2Σu+ and C2Σg+ states demonstrates that interactions for the He* access perpendicular to the molecular axis are more attractive than those for the collinear access, which is supported by the model calculations of the interaction potential energies. It is found that the perpendicular access plays an important role in a formation of the intermediate He++CS2− state.