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MO: Molekülphysik
MO 72: Collisions and Energy Transfer
MO 72.4: Vortrag
Freitag, 17. März 2006, 11:25–11:40, H10
Crossed beam study of the charge transfer from Ar+ to N2 — •J. Mikosch1,2, S. Trippel1, R. Berhane1, R. Otto1, D. Schwalm2, M. Weidemüller1, and R. Wester1 — 1Physikalisches Institut, Universität Freiburg, 79104 Freiburg — 2Max-Planck-Institut für Kernphysik, 69117 Heidelberg
Charge transfers are probably the most simple class of chemical reactions. Although chemical bonds are neither broken nor formed, this does surprisingly not impede charge transfer to be remarkably state-selective. In the electron transfer from Ar+ to N2(v=0) at low collision energies, the product ion N2+ is left most likely in the fist excited vibrational state via an endothermic channel with Δ E = −92meV. This non-adiabatic process is observed despite the fact, that production in the vibrational groundstate N2+(v=0) is exothermic by 179 meV.
We have used this reaction as a benchmark for our new apparatus, which combines crossed beams with velocity map imaging [1] to study reactive collisions at scattering energies below 1eV. For image analysis, a Monte Carlo Reconstruction (MCR) method has been developed. Within a narrow energy window we have observed large angle scattering. Also higher vibrational states seem to be populated in the N2+ product ion, which will be compared to earlier measurements [2]. An outlook on the study of nucleophilic substitution reactions, which are interesting due to their highly non-statistical behaviour, will be given.
[1] A.Eppink & D.Parker, Rev.Sci.Instr. 68, 3477 (1997) [2] K.Birkinshaw, A.Shukla, S.Howard and J.Futrell, Chem. Phys. 113, 149 (1987)