D. Rösch1, S. Willitsch1, Y.-P. Chang2, J. Küpper2,3,4
1Department Chemie, Universit&amul;t Basel, 4056 Basel, Switzerland
2Center for Free-Electron Laser Science, DESY, 22607 Hamburg, Germany
3Department of Physics, University of Hamburg, 22761 Hamburg, Germany
4Center for Ultrafast Imaging, University of Hamburg, 22761 Hamburg, Germany
Different conformations (torsional isomers, rotamers) of large, complex molecules can exhibit different reactivities. This provides a perspective to manipulate chemical reactions by selecting molecular conformations . However, a detailed understanding of the role of conformations in gas-phase chemical reactions still has to be established. We demonstrate the manipulation in terms of conformation in gas phase by carrying out reactive collisions between conformer-selected neutral molecules  and Coulomb crystals of laser-cooled Ca+ ions . 3-Aminophenol is a prototypical complex molecule that exhibits two different conformations (cis and trans) with different permanent electric dipole moments. They can be spatially separated in a molecular beam passing through an electrostatic deflector . Coulomb-crystals of Ca+ ions in an ion trap  serve as a suitable stationary target for reactive collisions with deflected molecular beams, as well as high sensitivities down to the level of single dynamical events. We present preliminary experimental results of conformer-specific reaction rates and theoretical calculations.
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