Berlin 2005 – scientific programme
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MO: Molekülphysik
MO 42: Poster II
MO 42.13: Poster
Tuesday, March 8, 2005, 14:00–16:00, Poster HU
Imaging of anion-molecule reaction dynamics — •J. Mikosch1,2, U. Frühling2, M. Weidemüller2, D. Schwalm1, and R. Wester2 — 1Max-Planck-Institut für Kernphysik, 69117 Heidelberg — 2Physikalisches Institut, Universität Freiburg, 79104 Freiburg
Understanding and manipulating the quantum mechanical dynamics of anion-molecule reactions is the goal of our experiment. Reactions of negative molecular ions and clusters are important in various environments, from solution-phase chemistry to the Earth’s atmosphere. A good example are nucleophilic substitution reactions [1], such as OH− + CH3F—→ F− + CH3OH which often evade a good desciption by standard statistical theories. First four-dimensional quantum scattering calculations have only been done recently, showing a strong dependence of total and differential cross sections on the rovibrational and translational degrees of freedom [2].
We have built an anion-molecule crossed beam experiment with a velocity map imaging detector [3]. The anions for the scattering process are supplied by a multipole RF ion trap, in which we utilize sympathetic cooling of the internal and translational excitations with buffer gas. A pulsed supersonic beam provides the neutral molecules. First experimental results will be presented.
In the future, also microsolvation effects will be studied using water cluster anions.
[1] L. Sun, K. Song, W. Hase, Science 296, 875 (2002) [2] S. Schmatz, ChemPhysChem 5, 601 (2004) [3] A. T. J. B. Eppink and D. H. Parker, Rev. Sci. Instrum. 68, 3477 (1997)