Eur. Phys. J. D 38, 75-84 (2006)
https://doi.org/10.1140/epjd/e2005-00269-3

Collision-energy-resolved Penning ionization electron spectroscopy of toluene and chlorotoluenes

Stereodynamics in collisional ionization and anisotropic interactions with He^*(2³S) atoms

Department of Chemistry, Graduate School of Science, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan

Corresponding author: ^a ohnok@qpcrkk.chem.tohoku.ac.jp

Received: 27 July 2005
Revised: 7 September 2005
Published online: 4 October 2005

Abstract

Stereodynamics in ionization of toluene and o-, p-chlorotoluenes by collision with He^*(2³S) metastable atoms were investigated by two-dimensional collision-energy/electron-energy-resolved Penning ionization electron spectroscopy. Anisotropic interactions around the molecule were studied by the collision energy dependence of partial ionization cross-sections (CEDPICS) as well as model potential calculations, and shielding effect by the methyl group was observed in CEDPICS for ionization from Cl lone-pair orbitals of o- chlorotoluene. Attractive interaction with He^*(2³S) around the π orbital region was found to be larger for toluene rather than o-, p- chlorotoluenes. Exterior electron density (EED) calculation of partial ionization cross-sections in Penning ionization and negative CEDPICS for ionization band observed in ca. 4 eV in electron energy indicated that π^-2π⁺¹ shake-up state was observed in Penning ionization electron spectroscopy of toluene.