Osnabrück 2002 – wissenschaftliches Programm

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MO: Molekülphysik

MO 19: Poster II (Energietransfer, Reaktionen, Photoionisation, Femtosekundenspektroskopie, ultrakurze Pulse)

MO 19.7: Poster

Donnerstag, 7. März 2002, 17:30–19:30, Schloss

Direct Observation of the Steric Effect in Penning Ionisation Reaction of Oriented Ar^*(³P_2,0)+CHCl₃→CHCl₂⁺+Cl+e⁻+Ar — •Masanori Yamato, Seiki Okada, Victor Wei-Keh Wu, Hiroshi Ohoyama, and Toshio Kasai — Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan

Steric effect in Penning ionization of oriented Ar^*(³P_2,0) + CHCl₃→CHCl₂⁺ +Cl + e⁻ + Ar has been directly observed at E_rel=0.13eV. CHCl₂⁺ ions were measured for H-end, CCl₃-end and sideways orientations. The steric opacity function reveals that CCl₃-end orientation is more favorable than H-end, and the sideways approach is to be more favorable than collinear approaches with both ends. There is Good correlation between the Penning ionization anisotropy and electron density distribution of the 2a₂ HOMO orbital of CHCl₃ around the sideways, by ab initio calculation with QCISD level on the 6-31+G(d) basis sets of GAUSSIAN-98. The exp. ion densities are CCl₃-end sideways H-end, though the existence of node of the molecular orbital and local max. of the closest distance at the coaxial approaches rather don’t prefer the collinear approach with CCl₃-end. The Penning ionization can probe well the spatial shape of molecular orbitals. The anisotropies of interaction and electron density distribution of the molecular orbital around the impact parameter near zero should be further investigated. Ref. J.C.P.113, 6673 (2000). *Victor Basic Research Laboratory e.V., Bielefeld, Germany, http://www.uni-bielefeld.de/fkure, with full financial aids of JSPS in 1999-2000 (No.L99536).