Book of Abstracts Book of Abstracts - Universität Konstanz

A - 20
Decay behaviour of dimer ions: kinetic energy distributions and 1/t law
J. Fedor 1 , K. Głuch 2 , S. Matt-Leubner 1 , O. Echt 3 , P. Scheier 1 , F. Hagelberg 4 , K. Hansen 5 , J. U. Andersen 6 ,
T. D. Märk 1
1 Institute for Ion Physics, Innsbruck University, Technikerstrasse 25, A-6020 Innsbruck, Austria
2 Institute of Mathematics, Physics and Informatics, Maria Curie-Skłodowska University, Lublin 20-031,
Poland
3 Dept. of Physics, University of New Hampshire, Durham, NH 03824, USA
4 Dept. of Physics, Atmospheric Sciences, and General Science, Jackson State University, Jackson, MS
39217, USA
5 Department of Physics, Gothenburg University, SE-41296 Gothenburg, Sweden
6 Institute of Physics and Astronomy, University of Aarhus, DK-8000 Aarhus, Denmark.
There exists a plethora of data on metastable decay of large cluster ions. For instance, the
analysis of the kinetic energy distributions of fragment ions has led to the evaluation of their
binding energies [1] and the time dependence of the decay intensity has been shown to obey a
powerlaw [2]. These decays have been successfully described with statistical theories.
Dimers represent the system where the degree of randomization required for thermal statistical
treatment is not possible. Experimental findings on dimer ions however show that they can have
decay characteristics resembling those of the large clusters.
Here we present the measurements of the kinetic energy release distributions of the rare gas
dimer anions (Ne2 + , Ar2 + , Kr2 + , Xe2 + ) using a three sector field mass spectrometer, as well as the
measurements of decay intensity time dependence for the dissociation of the metal dimer anions
(Cu2 - , Ag2 - ) obtained on the ELISA storage ring in Aarhus. The decay behaviour has been
successfully explained either by the metastable electronic transitions in case of rare gases or by
the tunneling through the high angular momentum barrier in the metal anions. The quasicontinuum
of rotational states in the later case is sufficiently dense to lead to a 1/t law.
References
[1] K. Gluch, S. Matt-Leubner, O. Echt, R. Deng, J.U. Andersen, P. Scheier and T.D. Märk, Chem.
Phys. Lett. 385 449 (2004)
[2] K.Hansen, J.U.Andersen, P.Hvelplund, S.P.Møller, U.V.Pedersen and V.V.Petrunin,
Phys.Rev.Lett. 87 123401 (2001)
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