Conserved Dynamics and Interface Roughening in Spontaneous Imbibition : A Critical Overview

Imbibition phenomena have been widely used experimentally and theoretically to study the kinetic roughening of interfaces. We critically discuss the existing experiments and some associated theoretical approaches on the scaling properties of the imbibition front, with particular attention to the conservation law associated to the fluid, to problems arising from the actual structure of the embedding medium, and to external influences such as evaporation and gravity. Our main conclusion is that the scaling of moving interfaces includes many crossover phenomena, with competition between the average capillary pressure gradient and its fluctuations setting the maximal lengthscale for roughening. We discuss the physics of both pinned and moving interfaces and the ability of the existing models to account for their properties.Comment: 9 pages, Late

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

Small rare gas clusters in soft X-ray pulses

We develop a microscopic model for the interaction of small rare gas clusters with soft X-ray radiation. It is shown that, while the overall charging of the clusters is rather low, unexpectedly high atomic charge states can arise due to charge imbalances inside the cluster. The mechanism does not require unusually high absorption rates, and the heating can be described by standard inverse bremsstrahlung formulae.Comment: 4 pages, 4 figure

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