Dresden 2011 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 26: Poster III

A 26.7: Poster

Donnerstag, 17. März 2011, 16:00–18:30, P2

Electron induced dissociation of H2 and CO2: molecular frame (e, 2e) spectroscopy — •Xueguang Ren, Thomas Pflüger, Shenyue Xu, Arne Senftleben, Alexander Dorn, and Joachim Ullrich — Max-Planck-Institut für Kernphysik , 69117 Heidelberg, Germany

Collisions of energetic electrons with molecules that induce chemical and physical reactions are of fundamental importance for a range of areas from plasma physics to radiation damage in living tissue. The study of dissociative ionization of molecules where the molecular ion is fragmenting can provide detailed insight into the molecular reaction dynamics. In this work experiments were performed for H2 and CO2 at low collision energy (E0 = 54.5 eV). A Reaction Microscope was used to measure the momentum vectors of all charged particles emerging from the collision. While for fast electron impact ionization can be well understood as a pure binary collision of the projectile and the target electron, at low energy the ionic potential and, therefore, the molecular structure and its alignment relative to the projectile beam can strongly influence the electron emission pattern. This was demonstrated recently in non-perturbative calculations [1]. Therefore, an important aspect of our measurement is the determination of the molecular axis alignment during the collision. This was realized by detecting the momentum vector of an ionic fragment resulting from the post-collision dissociation of the molecular ion. Fully differential cross sections as well as their interpretation will be delivered at the conference. [1] J. Colgan, et al., Phys. Rev. Lett. 101, 233201 (2008).