Berlin 2001 – wissenschaftliches Programm

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MO: Molekülphysik

MO 8: Posters Thursday: Dissociation and other Collision Processes

MO 8.1: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT3

Molecular Deformation of CO₂ in the C1s⁻¹ 2π excited state — •M. Hattass¹, N. Saito², A. Czasch¹, T. Weber¹, H. Schmidt-Böcking¹, and K. Ueda³ — ¹Institut für Kernphysik der J.W.Goethe Universität, August-Euler-Str. 6, D-60486 Frankfurt am Main, Germany — ²Electrotechnical Laboratory, Tsukuba 305-8568, Japan — ³Research Institute for Scientific Measurements, Tohoku University, Sendai 980-8577, Japan

The (Z+1) Model describes the innershell excited state of a Z atom in the lowest unoccupied molecular orbital as the ground state of the (Z+1) molecule, e.g. CO₂ in the C1s⁻¹ 2π excited state can be approximated by NO₂ in the ground state. This means the initially linear CO₂ molecule deforms after photo excitation into a bend geometry, according to the bend ground state of NO₂ with a bond angle of ∼134^∘. The excitation however leads to a subsequent Auger decay and ionisation of all atoms followed by the coulomb explosion of the molecule. We have measured the complete 3D momentum distribution of all three fragment ions of CO₂ after photo absorption into the the C1s⁻¹ 2π excited state by means of Cold Target Recoil Ion Momentum Spectroscopy (COLTRIMS). From these we can extract the angles between the two O⁺ and therefore directly probe the (Z+1) model. The results clearly show a shift in the angle distribution according to the (Z+1) model.