Asymmetric High-Energy Ion Emission from Argon Clusters in Intense Laser Fields

Abstract

Clusters of 2x10(3) to 4x10(4) Ar atoms are Coulomb exploded in intense (up to 8x10(15) W cm(-2)) laser fields. The dependence of multiply charged argon ion energies on the polarization state of light is probed. A directional asymmetry in the ion-explosion energies is observed for the highest charge states. The ion-energy distribution consists of a low-energy isotropic component, and a high-energy anisotropic one. The results are discussed in terms of an asymmetric Coulomb-explosion scenario.

Explosions of water clusters in intense laser fields

“…The application of 2D-TOF methodology to atomic [2,19] and molecular clusters opens new vistas for such research; as the present results indicate, it also questions prevailing wisdom regarding cluster explosion dynamics. The method certainly establishes the fact that water clusters formed by seeding with high pressure argon gas can be used to produce energetic and highly-charged ions of oxygen.…”

“…Our experiments on Ar n clusters, with n as large as 40000, reveal an ion energy dependence that scales approximately as q 2 . On the other hand, experiments that we conducted on Xe n clusters [19], with n ∼ 150000, yielded definite evidence that the explosion dynamics in this case most definitely occurred in the hydrodynamic regime (even though our results indicated the need to introduce a twodimensional component into the hydrodynamic expansion model in order to rationalize the asymmetry in the ion emission process that was discovered.) The present results indicate a linear dependence of ion energy of charge state in the case of relatively small water clusters, (H 2 O) n and (D 2 O) n , n ∼60, that have been produced by seeing high pressure He and Ar gases.…”

“…Even if we disregard the inevitable temporal widths of the TOF peaks associated with each of these ion species, it is clear that conventional TOF spectrometry would not enable us to disentangle the plethora of ions that would appear in the flight time region of 2.5 µs. Figure 5 shows a two-dimensional spectrum of Ar 40000 constructed from a series of spectra taken with different RPA voltages.We have reported this spectrum earlier [19] in connection with the discovery of asymmetric ion emission upon fragmentation of Ar 40000 clusters. As noted above, the 2D spectrum represents charge-resolved ion yields as a function of ion kinetic energy.…”

Parallel implementation of three-dimensional molecular dynamic simulation for laser-cluster interaction

“…al. [23]. They had shown that the explosion of Ar 40,000 cluster after the interaction of the 100 fs, 806 nm laser pulse with peak intensity of 8 × 10 15 W/cm 2 , results in an anisotropic ion energy distribution.…”

“…3 and 4 (∼ 200 keV) are in good agreement with the experimental findings. The anisotropic explosion of the cluster is explained on the basis of charge-flipping model [23]. Rapid oscillations of the electrons in the laser field cause the atoms on the laser polarization axis to be more ionized resulting in more energetic ions along the laser polarization compared to their number in direction perpendicular to it.…”