arXiv subjects

Christian Siedschlag

Publications and source records attributed to Christian Siedschlag.

3 recordsLinked to original sources

arXiv2002

Enhanced ionization in small rare gas clusters

A detailed theoretical investigation of rare gas atom clusters under intense short laser pulses reveals that the mechanism of energy absorption is akin to {\it enhanced ionization} first discovered for diatomic molecules. The phenomenon is robust under changes of the atomic element (neon, argon, krypton, xenon), the number of atoms in the cluster (16 to 30 atoms have been studied) and the fluency of the laser pulse. In contrast to molecules it does not dissappear for circular polarization. We develop an analytical model relating the pulse length for maximum ionization to characteristic parameters of the cluster.

physics.atm-clus↗

arXiv2002

Electron release of rare gas atom clusters under an intense laser pulse

Calculating the energy absorption of atomic clusters as a function of the laser pulse length $T$ we find a maximum for a critical $T^*$. We show that $T^*$ can be linked to an optimal cluster radius $R^*$. The existence of this radius can be attributed to the enhanced ionization mechanism originally discovered for diatomic molecules. Our findings indicate that enhanced ionization should be operative for a wide class of rare gas clusters. From a simple Coulomb explosion ansatz, we derive an analytical expression relating the maximum energy release to a suitably scaled expansion time which can be expressed with the pulse length $T^*$.

physics.atm-clus↗

arXiv2000

Time dependent energy absorption of atomic clusters from an intense laser pulse

For the energy absorption of atomic clusters as a function of the laser pulse duration we find a similar behavior as it has been observed for metallic clusters [Köller et al., Phys. Rev. Lett. {\bf 82}, 3783 (1999)]. In both situations there exists an optimum radius $R_{o}$ of the cluster for energy absorption. In the metallic case the existence of $R_{o}$ has been interpreted as a consequence of the collective oscillation of a delocalized electron cloud in resonance with the laser frequency. Here, we give evidence that in the atomic cluster the origin of $R_{o}$ is very different. Based on field assisted tunneling it can be related to the phenomenon of enhanced ionization as it occurs in small molecules. The dependence of $R_{o}$ on the laser frequency turns out to be the key quantity to distinguish the processes.

physics.atm-clus↗