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A: Atomphysik
A 13: Poster HU 2
A 13.57: Poster
Dienstag, 8. März 2005, 08:30–18:30, Poster HU
Electron impact single ionization of Ar2 in comparison with Ar — •Christina Dimopoulou, M. Dürr, A. Dorn, D. Nandi, and J. Ullrich — Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, D-69117, Heidelberg
Argon van der Waals dimers as well as atomic Ar, both present in the same supersonic gas-jet, have been ionized by 1 keV electron impact in a kinematically complete experiment using the COLTRIMS technique (reaction microscope). The momenta of the emitted electron and the recoil ion (Ar2+ or Ar+, respectively) have been measured in coincidence. Thus, the obtained electron energy distributions for Ar2 and Ar could be compared directly in order to identify "molecular" effects for the dimer. First, since the de Broglie wavelength of the emitted electron was comparable to the interatomic distance of Ar2, two-center interference effects are expected. Second, for Ar2 the emission of very low-energy electrons is enhanced. This is due to excitation of Ar2 followed by autoionization, an effect involving the coupling between the electronic and the nuclear motion in the dimer. The experimental results will be presented and discussed. Whenever possible, a comparison with previous data on single ionization of H2 [2] and with theoretical calculations will be made.
N. Stoltherfoht et al., Phys. Rev. Lett., 87, 023201 (2001)
C. Dimopoulou et al., Phys. Rev. Lett., 93, 123203(2004)