Berlin 2001 – scientific programme

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A: Atomphysik

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

A 12.2: Poster

Thursday, April 5, 2001, 12:30–15:00, AT3

Electron emission from He₂²⁺ quasi molecules — •Lothar P. H. Schmidt¹, Reinhard Dörner², Thorsten Weber¹, Ottmar Jagutzki¹, Feras Afaneh¹, Oliver Hohn¹, Kurt E. Stiebing¹, and Horst Schmidt-Bocking¹ — ¹Institut für Kernphysik, Universität Frankfurt, Germany — ²Fakultät für Physik, Universität Freiburg, Germany

We studied the electron emission in He²⁺- He collisions at projectile velocities between 0.6 and 1 a.u., using recoil-ion-momentum-spectroscopy (COLTRIMS). A newly developed electron spectrometer with 4 π solid angle for slow electrons has been implemented for the determination of the electron 3-dimensional momentum vector. The final-state energy eigenvalue of the bound electron has been determined in addition to the complete momentum distribution of all particles. During the collision a He₂²⁺ quasi molecule is formed by the projectile and target atom. Electron emission from this molecule is possible by the saddle-point mechanism. Knowing the binding energy and the assignment of the remaining electron to one of the nuclei one can distinguish four ionisation channels. The structures of the differential cross sections and the relation between these ionisation channels will be discussed in a molecular orbital approach.