Hannover 2003 – wissenschaftliches Programm

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MO: Molekülphysik

MO 6: Poster I

MO 6.24: Poster

Dienstag, 25. März 2003, 16:00–18:30, Lichthof

Direct Observation of the Steric Effect in Penning Ionisation Reaction of Oriented Ar^*(³P_2,0)+CHCl₃→CHCℓ₂⁺+Cℓ+e⁻+Ar (II) — •Masanori YAMATO¹, Seiki OKADA¹, Victor Wei-Keh WU^1,2,3, Hiroshi OHOYAMA¹, and Toshio KASAI¹ — ¹Department of Chemistry, Graduate School of Science, Osaka University, Toyonaka, Osaka 560-0043, Japan — ²Victor Basic Research Laboratory e.V., Gadderbaumer-Str. 22, D-33602 Bielefeld, Germany — ³Department of Electronic Engineering, Lan-Yang Institute of Technology, 261 Tou-Cheng, I-Lan, Taiwan, Republic of China

Steric effect in Penning ionization of oriented Ar^*(³P_2,0)+
CHCℓ₃→CHCℓ₂⁺+Cℓ+e⁻+Ar has been directly observed at E_rel = 0.13 eV. 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 betw. the Penning ionization anisotropy and electron density distr. of the 2a₂ HOMO orbital of CHCℓ₃ around the sideways, by ab initio calc. with QCISD level on the 6-31+G(d) basis sets of GAUSSIAN-98. Dynamical simulation is sofar impossible, because three bond lengths of CCℓ₃ of CHCℓ₃ are not differentiable during the reaction, even immediately before one Cℓ is released, and the involved PES cannot be reconstructed. Ref. J.C.P.113, 6673 (2000). Wu is deeply thankful for the full financial aids of JSPS in 1999−2000 (No.L99536), all the colleagues and friends, who have helped and taught him, and the kindly hospitality of Prof.Dr.Kasai.