Proceedings - Interdisciplinary Center for Nanotoxicity

Conference on Current Trends in Computational Chemistry 2009
Excitation functions of the channel of collision‐induced
dissociation in the systems XeCs + + Kr and XeCs + + Br ‐
V.M. Azriel, L.Yu. Rusin
Institute of Energy Problems of Chemical Physics, the Russia Academy of Sciences
Leninski prospect 38, Bldg.2, Moscow 119334, Russia
E­mail: Azriel_Vladimir@mail.ru
Trajectory simulation of dynamics of interaction in the systems XeCs + + Kr and XeCs + + Br ‐
is executed at collision energies ranging from 0 to 25,0 eV. Investigated reactions play
significant role in processes of collision dissociation and ionic recombination in an upper
atmosphere and an ionosphere at thermal and above‐thermal energies. It is necessary to notice
that atom Kr and an ion Br ‐ are isoelectronic particles with almost equal masses. Bond energy in
ionic complex XeCs + is near 0,1085 eV. Calculation shows that excitation functions of the
channel of collision‐induced dissociation for both systems have qualitatively similar behaviour
in all range of collision energies, however are characterized by different values of threshold
energy. For system XeCs + + Kr the channel opens at collision energy corresponding to bond
energy of an ionic complex while for system XeCs + + Br ‐ the threshold energy is equal 0,21 eV
that in 2 times exceeds bond energy of an ionic complex (figure 1). The difference in threshold
energies deals with, apparently, with character of interaction of ion Cs + with the third particle.
For system XeCs + + Br ‐ at energies below 0,2 eV more than 99% of all trajectories lead to
exothermic reaction of formation of molecule CsBr.
Cross section, arb. units
100
80
60
40
20
XeCs + + R -> Xe + Cs + + R
R=Kr
R=Br -
0
0,0 0,2 0,4 0,6 0,8 1,0
Collision energy, eV
Figure 1. Excitation functions of collision‐induced dissociation for the systems XeCs + + Kr and
XeCs + + Br ‐ near threshold.
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