Stuttgart 2012 – wissenschaftliches Programm
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A: Fachverband Atomphysik
A 23: Poster: Electron scattering and recombination
A 23.5: Poster
Dienstag, 13. März 2012, 16:30–19:00, Poster.V
Investigation into anomalies in electron scattering cross sections of H2 and D2 molecules — •Adrian Menssen1, Florian Trinter1, Markus Waitz1, Markus Schöffler1,3, Daniel Fischer2, Horst Schmidt-Böcking1, and Reinhard Dörner1 — 1Goethe Universität, Frankfurt, Germany — 2Max-Planck-Institut für Kernphysik, Heidelberg, Germany — 3Institut für Photonik, TU Wien, Gusshausstraße 27, Wien, Austria
For scattering of electrons or neutrons at a molecule at sufficiently high momentum transfers intramolecular dynamics and coherence effects are typically neglected: One only considers a binary scattering process between the incident electron and one constituent of the molecule. However recent experiments suggested an unexpected breakdown of this binary scattering approximation. Cooper et al. observed differences of up to 30 % in the total electron scattering cross-sections of H2 and D2: H2 appeared to be “smaller ”than expected.
We have been aiming to observe this same effect, however in a different experimental approach at momentum transfers between 2 and 4 a.u. Hydrogen-like O7+ and Magnesium Mg11+ were accelerated to energies between 30 and 90 MeV and then crossed with a supersonic gas-jet (50:50 mixture of H2 and D2) at 298 K. The projectile can be ionised by interaction of its electron with the target-molecule nucleus (n-e) or with one of the molecular electrons (e-e). Both processes (n-e and e-e) can be distinguished in momentum space.