Explosions of Xenon Clusters in Ultraintense Femtosecond X-Ray Pulses from the LCLS Free Electron Laser

Abstract

Explosions of large Xe clusters (<N> ~ 11,000) irradiated by femtosecond pulses of 850 eV x-ray photons focused to an intensity of up to 10(17) W/cm(2) from the Linac Coherent Light Source were investigated experimentally. Measurements of ion charge-state distributions and energy spectra exhibit strong evidence for the formation of a Xe nanoplasma in the intense x-ray pulse. This x-ray produced Xe nanoplasma is accompanied by a three-body recombination and hydrodynamic expansion. These experimental results appear to be consistent with a model in which a spherically exploding nanoplasma is formed inside the Xe cluster and where the plasma temperature is determined by photoionization heating.

Femtosecond X-ray-induced explosion of C60 at extreme intensity

“…1d). Although secondary ionization has been previously reported in the case of very large Xe vdW clusters 41 and solid aluminium 19 , our investigation, to the best of our knowledge, reveals for the first time significant collisional ionization within a single molecule exposed to intense X-rays.…”

“…Specifically, we demonstrate the effects of high per-atom X-ray absorption on the fragmentation dynamics of C 60 molecules in the gas phase. C 60 offers a number of advantages as a benchmark molecule when compared with isolated atoms [29][30][31][32][33] , small molecules [34][35][36][37][38][39][40] or van der Waals (vdW) clusters 41,42 , from the perspective of radiation damage. C 60 consists of chemically bonded carbon atoms with representative bond lengths and damage processes.…”

Hydrodynamic model for expansion and collisional relaxation of x-ray laser-excited multi-component nanoplasma

“…Timescales of collisional processes, their interplay in time, and, finally, the expansion dynamics agree qualitatively with observations from previous simulations and experiments. 4,6,11,18 To emphasize, the hydrodynamics simulations were performed on a single CPU for a large Ar cluster (>80000 atoms) and took around 24 h for 1 ps simulation. This is significantly faster than the previously quoted MD calculations which-to remind-took 48 h on a single CPU for a 1.5 ps long simulation of Ar 1000 cluster.…”

“…In particular, the progressing experimental studies of FEL irradiated atomic clusters 4,5 contribute towards the understanding of the behavior of radiation-induced ionization dynamics within complex systems. Recently, a nanoplasma formation following the irradiation of Ar cluster by a femtosecond x-ray pulse was also reported in Ref.…”

A validation of a simple model for the calculation of the ionization energies in X-ray laser-cluster interactions

“…This initial attempt met with good success. 5,[11][12][13][14] Another proposed model, titled LIT, postulated that the ionization could be modeled by incorporating the effects of the cluster on the atom or ion. This is done by approximating the inner-ionization threshold as the outer-ionization threshold, and then using well-known experimental atomic gas data as if the "dressed" atom was outside of a cluster 1070-664X/2015/22(2)/022123/6 V C Author(s) 2015 22, 022123-1 environment.…”