https://doi.org/10.1140/epjd/e2004-00109-0
Charged cores in ionized 4He clusters III: A quantum modeling for the collisional relaxation dynamics
1
Department of Chemistry and Industrial Chemistry, University of Genoa,
via Dodecaneso 31, 16146 Genoa, Italy
2
Department of Chemistry and INFM, University of Rome “La Sapienza”,
Piazzale A. Moro 5, 00185 Rome, Italy
Corresponding author: a fa.gianturco@caspur.it
Received:
24
March
2004
Revised:
15
June
2004
Published online:
24
August
2004
When a pure droplet is ionized by electron impact,
the most abundant fragment detected in mass spectra after ionization
is
. All the models that have been proposed
thus far to explain the experimental evidence therefore involve the
formation of the
molecular ion. The understanding
of the interactions between this ion and the surrounding
atoms in the cluster and of their dynamical behavior during cluster
break-up is an important element for the modeling of the cluster evolution
after the ionization event. In previous works [CITE]
we have computed and described the Potential Energy Surface (PES)
of the electronic ground state for the
system
that provides the required forces between
and
. After ionization
is presumably
formed by association of an
and any of the neutral
atoms in the cluster via a 3-body collision process. The ensuing vibrational
quenching of the “hot” molecular ion may release the energy
necessary to evaporate the entire droplet, or most of it, and give
the fragmentation patterns detected by experiments. We present here
a model quantum dynamics that generates vibrational deexcitation cross-sections and the corresponding rate coefficients for the collision
of
with
. A timescale of the
cluster evaporation due to vibrational relaxation is estimated and
the present findings are compared with earlier studies on the same
system.
PACS: 31.15.Qg – Molecular dynamics and other numerical methods / 34.50.Ez – Rotational and vibrational energy transfer / 36.40.Wa – Charged clusters
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004