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 $\sigma \propto E^{\alpha}$ and we show that the $\alpha$ determined in the interval between 2-5 eV deviates from the analytical threshold value of 2.16 which we find in the interval between $0.1-2$ 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