title: Anisotropic interaction and stereoreactivity in a chemi-ionization process of OCS by collision with He*(2(3)S) metastable atoms.
abstract: Ionic-state-resolved collision energy dependence of Penning ionization cross sections for OCS with He*(2(3)S) metastable atoms was measured in a wide collision energy range from 20 to 350 meV. Anisotropic interaction potential for the OCS-He*(2(3)S) system was obtained by comparison of the experimental data with classical trajectory simulations. It has been found that attractive potential wells around the O and S atoms are clearly different in their directions. Around the O atom, the collinear approach is preferred (the well depth is ca. 90 meV), while the perpendicular approach is favored around the S atom (the well depth is ca. 40 meV). On the basis of the optimized potential energy surface and theoretical simulations, stereo reactivity around the O and S atoms was also investigated. The results were discussed in terms of anisotropy of the potential energy surface and the electron density distribution of molecular orbitals to be ionized.
authors.affiliation: Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai, 980-8578, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Horio
authors.forename: Satoshi
authors.initials: S
authors.lastname: Maeda
authors.forename: Naoki
authors.initials: N
authors.lastname: Kishimoto
authors.forename: Koichi
authors.initials: K
authors.lastname: Ohno