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A: Atomphysik

A 12: Posters Thursday (Ion/Atom/Molecule/Surface Scattering)

A 12.31: Poster

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

Penning and associative ionization in collisions of state-selected metastable Ar^* atoms with mercury atoms^⋆ — •L. Thiel¹, D. Spelsberg², W. Meyer², F.A.U. Thiel¹, A.J. Yencha³, and H. Hotop¹ — ¹Department of Physics, University of Kaiserslautern, D-67663 Kaiserslautern, Germany — ²Department of Chemistry, University of Kaiserslautern, D-67663 Kaiserslautern, Germany — ³Department of Chemistry, State University of New York at Albany, NY 12222, USA

We have carried out experimental and theoretical studies of Penning and associative ionization processes occurring in thermal energy collisions of state-selected metastable Ar^*(4s ³P_2,0) atoms with ground state mercury atoms. State selection of the two metastable Ar^* levels ³P₂ and ³P₀ was achieved with an optical pumping method involving scanning diode lasers. Electron energy spectra, measured with a crossed-beam set-up perpendicular to the collision velocity at an energy resolution of about 35 meV, are reported. The experimental electron spectra are analyzed by carrying out model calculations based on the local complex potential approximation. The obtained ‘best-fit’ model potential for Ar^*-Hg is compared to the potential energy curve of the K(4s)-Hg system (in the spirit of the notion that in many respects metastable rare gas atoms behave like alkali atoms) and to a preliminary ab initio potential for Ar^*-Hg obtained from multireference-configuration interaction (MR-CI) calculations using Feshbach projection.
^⋆ This work has been supported by the Deutsche Forschungsgemeinschaft and by the Graduiertenkolleg “Laser- und Teilchenspektroskopie”.