Skinning of argon clusters by Coulomb explosion induced with an intense femtosecond laser pulse

Abstract

The energy distributions of ions emitted from argon clusters Coulomb exploded at an intensity of Ͻ10 17 W/cm 2 with an intense femtosecond laser have been experimentally studied. The power m of energy E of the ion energy distribution ͑dN / dE ϳ E m ͒ is expected to be 1 / 2 for spherical ion clusters, but it is in fact reduced smaller than 1 / 2 as the laser intensity is decreased. This reduction can be well interpreted as resulting from the instantaneous ionization of the surface of the cluster. The validity of this interpretation was confirmed by experiments with double pulse irradiation. A cluster irradiated by the first pulse survives as a skinned cluster, and the remaining core part is Coulomb exploded by the second pulse. It is shown that a cluster can be skinned by an intense short laser pulse, and the laser-intensity dependence of the skinned layer thickness can be reasonably explained by the laser-induced space charge field created in the cluster.

High energy ion emission from a copper surface irradiated by a femtosecond laser pulse with the laser fluence of ablation threshold

“…The plasma wave slowly travels with the speed of ~10 -2 times of the light speed. For this instance ionenriched local area appears and until the next electron wave top arrives there, the ions there feel strong Coulomb repulsive force with each other and can be exploded to vacuum side, that is, Coulomb explosion [6] occurs, and then periodic grating structures will be formed. Mechanism of grating structure formation is under investigation.…”

Ergodic model for the expansion of spherical nanoplasmas

“…In fact, for expansion conditions far from a CE, the nonmonotonic behavior of the single-cluster ion spectra could affect the total (i.e., arising from all expanding clusters) energy spectrum measured in experiments: in particular, it could lead to nonmonotonic energy spectra, such as those presented in Ref. [10], also for narrow distributions of cluster radii.…”

“…The results presented here provide a complete characterization of the expansion dynamics of spherical nanoplasmas, which can be useful in the interpretation of recent experiments with clusters, either irradiated with intense IR lasers or with VUV/X-ray sources [14], where conditions may be far from those of a pure CE [10]. In particular, the different behavior observed in the ion energy spectrum for different values of the electron temperature allows a clear identification of the transition from hydrodynamic-like to CE expansion regimes, thus defining the range of validity of the CE approximation.…”

“…In contrast, the expansion of spherical plasmas [such as the nm-to µm-sized plasmas generated upon interaction of ultraintense lasers with atomic or molecular clusters (cf. [8,9,10,11,12])] have not been analyzed as thoroughly. A deep knowledge of the expansion (accounting for the self-consistent dynamics of ions and electrons) can be relevant in particular situations where accurate control over the expansion is necessary, examples being the double-pump irradiation of deuterium clusters aimed at tailoring the ion dynamics so as to induce intracluster fusion reactions [13], or the biomolecular imaging with ultrashort X-ray pulses [14], where expansion control is needed to avoid significant damages of the sample before the typical imaging time.…”

Ionization and Plasma Dynamics of Single Large Xenon Clusters in Superintense XUV Pulses

“…However, deducing the dominant expansion mechanism from the distributions of ion kinetic energies is a much-discussed topic [91,92,88,90,89,93,73,94,79]. A major difficulty of interpreting the kinetic energy distribution of ions arises from the averaging over many different intensities in the focus profile and different cluster sizes in the probed ensemble of clusters [95,96].…”