Study of polycyclic aromatic hydrocarbons in the solid state by collision energy resolved Penning ionization electron spectroscopy

Abstract

He *(2 3S) Penning ionization electron spectra (PIES) of chrysene (C 18H 12), perylene (C 20H 12), and coronene (C 24H 12) in the solid state were studied. Collision energy dependence of partial ionization cross-sections (CEDPICS) of solid state samples was measured for the first time. The CEDPICS of those samples shows positive and negative slopes depending on the final ionic states. As common features, negative CEDPICS for π bands and positive CEDPICS for ρ bands were observed. This indicates that the interactions between He *(2 3S) and those aromatic hydrocarbons are attractive in the region where π orbitals extend and are repulsive around the hydrogen atoms.