Penning ionization of cyclopropanes by collision with He*(2(3)S) metastable atoms

The Penning ionization of cyclopropane (C3H6), cyclopropylamine (C3H5NH2), and cyanocyclopropane (C3H5CN) upon collision with He*(2(3)S) metastable atoms was studied by collision energy resolved Penning ionization electron spectroscopy. Collision energy dependence of the partial ionization cross sections indicated that the interaction potentials are strongly anisotropic between He*(2(3)S) and the investigated cyclopropanes. In the studied energy range, the interaction potential was found to be attractive around the amino and cyano groups. A repulsive interaction potential was found around the carbon ring and hydrogen atoms for cyclopropane, and the order of the hardness was C-3 ring (out-of-plane direction) (hydrogen atoms < C-3 ring (in-plane direction). These are consistent with calculated interaction potential curves.