Darmstadt 2008 – wissenschaftliches Programm

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SYDP: Symposium Dissertationspreis

SYDP 1: Dissertationspreis Symposium

SYDP 1.3: Hauptvortrag

Dienstag, 11. März 2008, 09:30–10:00, 3C

Dynamics of anion-molecule reactions at low energy — •Jochen Mikosch, Sebastian Trippel, Rico Otto, Christoph Eichhorn, Petr Hlavenka, Matthias Weidemüller, and Roland Wester — Physikalisches Institut, Universität Freiburg

Ion-molecule reactions play a crucial role in our close and distant environment and constitute important model systems for the physics of few-body interactions. Reactions of negatively charged ions promise particularly rich dynamics since they must find their way through deeply bound entrance and exit channel ion-dipole complexes separated by a central barrier. On this characteristic potential energy surface direct pathways compete with the formation of transient intermediates.

With a novel experimental approach we image scattering dynamics of bimolecular nucleophilic substitution reactions at defined relative energy between 0.4 and 10 eV. In a second series of experiments we investigate the reaction probability and transient lifetimes at well defined variable temperature down to 8 Kelvin in a multipole trap. From our data and in collaboration with the theory group of Bill Hase, we identify several reaction mechanisms, including a new indirect “roundabout” mechanism. Our results shed new light on the dynamics of ion-driven chemistry and open up the perspective to investigate reactive scattering with spatially aligned reactants and of ions embedded in water clusters.