202 research outputs found
Stochastic dissociation of diatomic molecules
The fragmentation of diatomic molecules under a stochastic force is
investigated both classically and quantum mechanically, focussing on their
dissociation probabilities. It is found that the quantum system is more robust
than the classical one in the limit of a large number of kicks. The opposite
behavior emerges for a small number of kicks. Quantum and classical
dissociation probabilities do not coincide for any parameter combinations of
the force. This can be attributed to a scaling property in the classical system
which is broken quantum mechanically.Comment: 5 pages, 1 figure, accepted by J Chem Phy
Triple photoionization of Lithium near threshold
Solving the full classical four-body Coulomb problem numerically using a
Wigner initial distribution we formulate a classical-quantum hybrid approach to
study triple ionization by single photon absorption from the Li ground state in
the threshold region.
We confirm the Wannier threshold law and we show
that the determined in the interval between 2-5 eV deviates from the
analytical threshold value of 2.16 which we find in the interval between
eV.Comment: 6 pages, 3 figure
Attosecond resolved charging of clusters
Attosecond laser pulses open the door to resolve microscopic electron
dynamics in time. Experiments performed include the decay of a core hole, the
time-resolved measurement of photo ionization and electron tunneling. The
processes investigated share the coherent character of the dynamics involving
very few, ideally one active electron. Here, we introduce a scheme to probe
dissipative multi-electron motion in time. In this context attosecond probing
enables one to obtain information which is lost at later times and cannot be
retrieved by conventional methods in the energy domain due to the incoherent
nature of the dynamics. As a specific example we will discuss the charging of a
rare-gas cluster during a strong femtosecond pulse with attosecond pulses. The
example illustrates the proposed use of attosecond pulses and suggests an
experimental resolution of a controversy about the mechanism of energy
absorption by rare-gas clusters in strong vacuum-ultraviolet (VUV) pulses.Comment: 4 pages, 3 figure
Energy absorption of xenon clusters in helium nanodroplets under strong laser pulses
Energy absorption of xenon clusters embedded in helium nanodroplets from
strong femtosecond laser pulses is studied theoretically. Compared to pure
clusters we find earlier and more efficient energy absorption in agreement with
experiments. This effect is due to resonant absorption of the helium nanoplasma
whose formation is catalyzed by the xenon core. For very short double pulses
with variable delay both plasma resonances, due to the helium shell and the
xenon core, are identified and the experimental conditions are given which
should allow for a simultaneous observation of both of them.Comment: 4 pages, 4 figure
Surface plasma resonance in small rare gas clusters by mixing IR and VUV laser pulses
The ionization dynamics of a Xenon cluster with 40 atoms is analyzed under a
pum p probe scenario of laser pulses where an infrared laser pulse of 50 fs
length follows with a well defined time delay a VUV pulse of the same length
and peak intensity. The mechanism of resonant energy absorption due to the
coinc idence of the IR laser frequency with the frequency of collective motion
of quasi free electrons in the cluster is mapped out by varying the time delay
between the pulses
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