Heidelberg 1999 – scientific programme
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A: Atomphysik
A 8: Stöße II
A 8.5: Talk
Tuesday, March 16, 1999, 17:30–17:45, TE4
Paul-trap promotion in He+-He collision — •M. Busch1, R. Drozdowski2, and G. v. Oppen1 — 1Technische Universitaet Berlin, Institut fuer Atomare und Analytische Physik, Hardenbergstrasse 36, D-10623 Berlin, Germany — 2University of Gdansk, Institute of Experimental Physics, ul. Wita Stwosza 57, 80-952 Gdansk, Poland
Recently we have shown that Paul-trap promotion is a dominant
excitation mechanism in proton-helium collisions at intermediate
energies [1]. During the collision, one electron bound to the He
atom reaches the saddle of the two-center Coulomb potential of
proton and He+ core, and its motion is transiently stabilized
on the saddle due to the rotation of the molecular axis of the
collision system. In this work we studied the excitation of He
atoms by He+ ion impact using the same experimental techniques
as in [1]. Large electric dipole moments indicating a highly
asymmetric charge distribution of the transient state of the
collisionally excited electron were found for impact energies of
about 200 keV in accord with the Paul-trap model. Measurements
at energies down to 10 keV He+ are expected to reveal
indications of the transition to electron promotion via diabatic
molecular-orbital potential curves [2].
[1] S.Buettrich et al.: J. Phys. B 31 (1998) 2709
[2] F. J. de Heer and J. van den Bos: Physica 31 (1965) 365