Variable surface composition and radial interface formation in self-assembled free, mixed Ar∕Xe clusters

Tchaplyguine, Maxim; Lundwall, Marcus; Gisselbrecht, Mathieu; Öhrwall, Gunnar; Feifel, Raimund; Sorensen, S. L.; Svensson, S.; Mårtensson, Nils; Björneholm, Olle

doi:10.1103/physreva.69.031201

Cited by 67 publications

(65 citation statements)

References 18 publications

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“…Additionally, a larger core-shell system with N ≈ 4000 is prepared by expanding the same gas premix at 17 bars. For the current experimental conditions a Xe enrichment factor of about 10 has been measured in different previous investigations [21][22][23]. Therefore the core-shell structures can be roughly estimated to consist of a Xe core with approximately 1-2 and 3-4 Ar shells on top, respectively.…”

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confidence: 63%

“…At high concentrations exceeding 5-10% of Xe in Ar, pure Xe clusters are formed because then Ar acts merely as a seeding gas which is completely evaporated off the growing cluster. In a narrow range between 1-5% Xe in Ar a strong enrichment of the Xe in the cluster is observed [20][21][22]. The Xe nucleates in the core of the Ar cluster but not all Ar is evaporated [21,22].…”

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confidence: 97%

“…In a narrow range between 1-5% Xe in Ar a strong enrichment of the Xe in the cluster is observed [20][21][22]. The Xe nucleates in the core of the Ar cluster but not all Ar is evaporated [21,22]. This formation of the core-shell structure is due to phase separation resulting from the different cohesive energies and melting points of Xe and Ar.…”

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confidence: 98%

“…Thus, the enrichment factor of Xe in the Ar cluster, or in other words, the thickness of the Ar surface layer, depends sensitively on the Xe concentration of the gas premix. For the current experiments a gas premix of 2% Xe in Ar is expanded at 7 bars and nozzle temperatures of 300 K. These parameters have been chosen because they yield the same gas-independent cluster condensation parameter * [17,18] as in previous detailed photoelectron spectroscopy investigations about such systems [21]. The corresponding cluster size according to the scaling laws for pristine clusters [17,18] is N ≈ 400 with the typical size distribution N ≈ N full-width at half-maximum.…”

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Charge recombination in soft x-ray laser produced nanoplasmas

Hoener¹,

Thomas²,

Wabnitz³

et al. 2009

J. Phys.: Conf. Ser.

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The ionization and charge separation processes of nanoplasmas created by resonant excitation of atomic clusters in intense soft x-ray pulses have been investigated. Through irradiation with femtosecond pulses from the FLASH free electron laser (FEL) at λ = 13.7 nm and power densities exceeding 10 14 W cm −2 the clusters are highly ionized with transient atomic charge states up to 9+. Variation of the cluster composition from pristine to doped and core-shell systems allows tracking of the spatial origin and charge states of the fragments yielding insight into the nanoplasma dynamics. The data give evidence for efficient charge redistribution processes leading to a Coulomb explosion of the cluster outer part and recombination of the nanoplasma core. The experiments show qualitatively different processes for (soft) x-ray produced nanoplasmas from the optical (IR) strong-field regime where the clusters disintegrate completely in a Coulomb explosion.(Some figures in this article are in colour only in the electronic version)Understanding the interaction of light with matter has been a central theme of physics over the past century, starting with the concept of the photon and the inception of quantum theory. The invention of the laser and the continuing advance in laser technologies has made it possible to explore regimes of nonlinear light-matter interaction leading to novel laserbased concepts for particle accelerators, plasma formation and nuclear fusion [1]. Currently, we are witnessing the advent of intense lasers in the x-ray regime. One of the most exciting prospects of research with x-ray lasers is direct imaging of nonperiodic nanoscale objects, such as biomolecules, nanocrystals, living cells and viruses [2]. Even though it is crucial for the success of the imaging experiments, understanding the interaction of intense x-ray pulses with atomic systems and the underlying dynamics is still in its infancy. To date, virtually all studies about the ionization as well as nuclear dynamics of nanometer-sized structures in intense (soft) x-ray pulses are of theoretical nature [3][4][5][6] and no experimental data are available.For the experimental investigations of matter in intense light pulses atomic clusters are ideal because their size can be tuned from the molecular to the bulk-like regime and there is no energy dissipation into surrounding media. The ionization dynamics of clusters in intense laser pulses depend considerably on the radiation wavelength. In the infrared spectral regime the cluster is ionized by the optical field and the resulting transient nanoplasma is efficiently heated by the external laser field via inverse bremsstrahlung (IBS) and collective effects, leading to a Coulomb explosion of the cluster [7]. Because the ponderomotive energy scales with ω −2 (ω-laser frequency) and thus, the direct effect of the laser field on the electron movement is small, it was a big surprise when experiments in the vacuum-ultraviolet spectral regime at 100 nm and intensities up to 10 13 W cm −2 reported u...

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confidence: 63%

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confidence: 97%

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confidence: 98%

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confidence: 99%

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Charge recombination in soft x-ray laser produced nanoplasmas

Hoener¹,

Thomas²,

Wabnitz³

et al. 2009

J. Phys.: Conf. Ser.

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“…On van der Waals clusters, experiments using electron spectroscopy, 3,4 surface scattering with subsequent mass spectrometry, 5 and electron diffraction 6 have been carried out. Simulated results show far more detail than currently is experimentally accessible.…”

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confidence: 99%