Bonn 2000 – scientific programme
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A: Atomphysik
A 15: Poster I
A 15.6: Poster
Wednesday, April 5, 2000, 10:30–13:00, Aula
Kinetic energy release distributions in Coulomb explosion of N2 molecules induced by fast highly charged ion impact — •N. Kabachnik1, B. Siegmann1, U. Werner1, H.O. Lutz1, and R. Mann2 — 1Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld — 2Gesellschaft für Schwerionenforschung (GSI), 64291 Darmstadt
The dissociation of N2q+ molecular ions produced by 4.7 MeV/amu Bi57+,25+ and 5.9 MeV/amu Xe43+ ion impact on N2 has been studied using the coincidence technique with a position- and time-sensitive multi-particle detector. The kinetic energy release distributions for all observed ion pairs Nq1+ + Nq2+ are measured. The distributions are practically independent of the projectile charge and velocity. Analysis of the distributions is made with emphasis on the highly charged molecular ions, q > 3. In these cases the most probable total kinetic energy of the two fragments is well described by the Coulomb explosion model for point charges, while the measured width of the distributions is much larger than that predicted by this simplified model. We therefore suggest a more elaborate model of Coulomb fragmentation based on a statistical description of the individual potential energy curves of the molecular ion. This enables us to describe both the position and the width of the kinetic energy release distributions. We suggest that the main cause of the large width of the distributions for the high q values is the spread of the potential energy curves at the equilibrium internuclear distance; this is mainly due to the dispersion interaction arising from the mutual polarization of the atomic ions.