Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters

Hohenberger, M.; Symes, D. R.; Madison, Kirk W.; Sumeruk, A.; Dyer, G.; Edens, Aaron; Grigsby, W.; Hays, G.; Teichmann, Martin; Ditmire, T.

doi:10.1103/physrevlett.95.195003

Cited by 43 publications

(41 citation statements)

References 21 publications

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“…We found a new isotope effect that was not observed in earlier infrared studies [22,23]. The deuterons spend a longer time than protons closer to the charged core and thus can reach higher kinetic energies.…”

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confidence: 41%

“…The core of such large objects expands hydrodynamically due to the growing electron pressure within [17,18]. Theoretical studies predict a * Electronic address: nicusor@xray.bmc.uu.se transition from Coulomb explosion to hydrodynamic expansion with increasing sample size [13].The study of Coulomb explosion of molecular clusters with intense infrared lasers has shown the advantage of using heteronuclear molecules, such as CH 4 or CD 4 , to analyze the dynamics of the explosion [22,23]. In a heteronuclear cluster, the light ions can gain additional energy during the explosion by interacting with multiply charged heavy ions (C n+ ).…”

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confidence: 99%

“…The study of Coulomb explosion of molecular clusters with intense infrared lasers has shown the advantage of using heteronuclear molecules, such as CH 4 or CD 4 , to analyze the dynamics of the explosion [22,23]. In a heteronuclear cluster, the light ions can gain additional energy during the explosion by interacting with multiply charged heavy ions (C n+ ).…”

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confidence: 99%

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Explosion, ion acceleration, and molecular fragmentation of methane clusters in the pulsed beam of a free-electron laser

et al. 2012

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X-ray lasers offer new possibilities for creating and probing extreme states of matter. We used intense and short X-ray pulses from the FLASH soft X-ray laser to trigger the explosions of CH4 and CD4 molecules and their clusters. The results show that the explosion dynamics depends on cluster size, and indicate a transition from Coulomb explosion to hydrodynamic expansion in larger clusters. The explosion of CH4 and CD4 clusters shows a strong isotope effect: the heavier deuterons acquire higher kinetic energies than the lighter protons. This may be due to an extended inertial confinement of deuterons vs. protons near a rapidly charging cluster core during exposure. [5,6] and solid samples [7][8][9]. In this paper we follow the X-ray-induced explosion of methane (CH 4 ) and heavy methane (CD 4 ) clusters and compare the results to the explosion of the individual molecules. Clusters are eminently suitable to study size-dependent phenomena in the explosion dynamics, and we employed clusters, containing 1000 to 250000 molecules and corresponding to sizes of 4 -32 nm diameter. Molecular clusters bridge the gap between isolated molecules and bulk condensed material. An understanding of ultrafast explosion dynamics in clusters of various dimensions has relevance to imaging by "diffraction before destruction" [10], plasma physics, and fusion research [11,12].The target response to an intense X-ray pulse depends on the wavelength, the intensity of the field, and the size of the sample. Photoionization liberates electrons, which can escape from small samples, and these positively charged objects undergo a Coulomb explosion. The probability of electrons escaping from a cluster depends on its size [13][14][15]. In larger objects, photoelectrons elicit secondary electron cascades and these create additional ionizations. As the overall positive charge of the sample increases during the pulse, photoelectrons will not be able to escape the growing positive potential [13,16]. Trapped photoelectrons create more cascades and the electrons move inwards to neutralize the core of the cluster, leaving behind a positively charged outer layer, which then peels off [17][18][19][20][21]. As a result, large samples burn from the outside inwards. The core of such large objects expands hydrodynamically due to the growing electron pressure within [17,18]. Theoretical studies predict a * Electronic address: nicusor@xray.bmc.uu.se transition from Coulomb explosion to hydrodynamic expansion with increasing sample size [13].The study of Coulomb explosion of molecular clusters with intense infrared lasers has shown the advantage of using heteronuclear molecules, such as CH 4 or CD 4 , to analyze the dynamics of the explosion [22,23]. In a heteronuclear cluster, the light ions can gain additional energy during the explosion by interacting with multiply charged heavy ions (C n+ ). This kinematic effect would be indicative of a Coulomb process, while in a hydrodynamics expansion all the cluster constituents are expected to gain the same energy. We ...

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Explosion, ion acceleration, and molecular fragmentation of methane clusters in the pulsed beam of a free-electron laser

et al. 2012

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“…For large clusters, with R 0 R I 0 , the atom stripping intensity thresholds are considerably reduced as compared to the single atom, due to ignition effects [10] induced by the inner field of the ions (Fig. 1 [3][4][5][6][7][8][9]20,21]. Under CVI conditions, which are applicable for R 0 R I 0 , the energy of the majority of the ions from CE of heteroclusters lies in the vicinity of the maximal energy of E M [3,4,7,9,20,21], due to kinematic effects [3,4,7].…”

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Tabletop Nucleosynthesis Driven by Cluster Coulomb Explosion

Last

Jortner

2006

Phys. Rev. Lett.

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Coulomb explosion of completely ionized (CH4)n, (NH3)n, and (H2O)n clusters will drive tabletop nuclear reactions of protons with 12C6+, 14N7+, and 16O8+ nuclei, extending the realm of nuclear reactions driven by ultraintense laser-heterocluster interaction. The realization for nucleosynthesis in exploding cluster beams requires complete electron stripping from the clusters (at laser intensities I(M) > or = 10(19) W cm(-2)), the utilization of nanodroplets of radius 300-700 A for vertical ionization, and the attainment of the highest energies for the nuclei (i.e., approximately 30 MeV for heavy nuclei and approximately 3 MeV for protons).

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“…In this context, the investigation of hydrocarbon clusters like methane [20][21][22][23] and propane [24,25] clusters can be beneficial, as hydrogen and carbon are important constituents of organic molecules.…”

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Tracing transient charges in expanding clusters

Schütte¹,

Vrakking²,

Rouzée³

2017

Phys. Rev. A

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We study transient charges formed in methane clusters following ionization by intense nearinfrared laser pulses. Cluster ionization by 400 fs (I = 1 × 10 14 W/cm 2 ) pulses is highly efficient, resulting in the observation of a dominant C 3+ ion contribution. The C 4+ ion yield is very small, but is strongly enhanced by applying a time-delayed weak near-infrared pulse. We conclude that most of the valence electrons are removed from their atoms during the laser-cluster interaction, and that electrons from the nanoplasma recombine with ions and populate Rydberg states when the cluster expands, leading to a decrease of the average charge state of individual ions. Furthermore, we find clear bound-state signatures in the electron kinetic energy spectrum, which we attribute to Auger decay taking place in expanding clusters. Such nonradiative processes lead to an increase of the final average ion charge state that is measured in experiments. Our results suggest that it is crucial to include both recombination and nonradiative decay processes for the understanding of recorded ion charge spectra.The ionization of clusters by intense laser pulses induces highly complex dynamics that take place on attosecond to nanosecond timescales and that involve a large number of interacting particles. Intense lasercluster interactions commonly involve an ionization stage, the establishment of a nanoplasma and the subsequent expansion and break-up of this nanoplasma. Disentangling the different mechanisms is a very challenging task that requires sophisticated theoretical and experimental approaches. In spite of the large efforts that have been devoted to the study of laser-cluster interactions in the past 20 years (see e.g. [1-4]), the understanding of both the ionization and relaxation dynamics taking place during the cluster expansion are still far from being complete. For instance, up to now, experiments have only provided limited information about the relative importance of direct laser-induced (multi-photon and tunneling) ionization and electron-impact ionization by laserdriven electron-atom/ion collisions The development and application of pump-probe techniques promises novel insights into the relevant processes. For instance, the generation of seed electrons in a cluster by an extreme-ultraviolet (XUV) pulse allows the time-resolved investigation of strong-field processes induced by near-infrared (NIR) pulses [5]. Amongst the various processes that take place during the cluster expansion, electron-ion recombination processes are known to play an important role [1,3,[6][7][8][9]. Recently, recombination resulting in the production of a large number of excited atoms and ions was temporally resolved using pump-probe photoion and -electron spectroscopy [10][11][12], showing similar dynamics for clusters ionized by intense XUV and intense NIR pulses, respectively. These results suggest that the charge distributions that can be measured after the nanoplasma has expanded may differ significantly from the transient charge distributions ...

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Dynamic Acceleration Effects in Explosions of Laser-Irradiated Heteronuclear Clusters

Cited by 43 publications

References 21 publications

Explosion, ion acceleration, and molecular fragmentation of methane clusters in the pulsed beam of a free-electron laser

Explosion, ion acceleration, and molecular fragmentation of methane clusters in the pulsed beam of a free-electron laser

Tabletop Nucleosynthesis Driven by Cluster Coulomb Explosion

Tracing transient charges in expanding clusters

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