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Intensed pulsed laser

Daniela Rupp, Leonie Flückiger, Marcus Adolph, Tais Gorkhover, Maria Krikunova, Jan Philippe Müller, Maria Müller, Tim Oelze, Yevheniy Ovcharenko, Benjamin Röben, Mario Sauppe, Sebastian Schorb, David Wolter, Rolf Mitzner, Michael Wöstmann, Sebastian Roling, Marion Harmand, Rolf Treusch, Mathias Arbeiter, Thomas Fennel, Christoph Bostedt, Thomas Möller
We studied the nanoplasma formation and explosion dynamics of single large xenon clusters in ultrashort, intense x-ray free-electron laser pulses via ion spectroscopy. The simultaneous measurement of single-shot diffraction images enabled a single-cluster analysis that is free from any averaging over the cluster size and laser intensity distributions. The measured charge state-resolved ion energy spectra show narrow distributions with peak positions that scale linearly with final ion charge state. These two distinct signatures are attributed to highly efficient recombination that eventually leads to the dominant formation of neutral atoms in the cluster...
October 7, 2016: Physical Review Letters
Aram Gragossian, Denis V Seletskiy, Mansoor Sheik-Bahae
The interaction of intense near- and mid-infrared laser pulses with rare gases has produced bursts of radiation with spectral content extending into the extreme ultraviolet and soft x-ray region of electromagnetic spectrum. On the other end of the spectrum, laser-driven gas plasmas has been shown to produce coherent sub-harmonic optical waveforms, covering from terahertz (THz) to mid- and near-infrared frequency spectral band. Both processes can be enhanced via a combination of a driving field and its second harmonic...
October 19, 2016: Scientific Reports
M Pang, W He, P St J Russell
We report a Tm-doped soliton fiber laser passively mode-locked by intense optoacoustic interactions in a short length of solid-core silica photonic crystal fiber (PCF) with a nanobore in core-center. A repetition rate of 1.446 GHz pulse is achieved, corresponding to the 52nd harmonic of the 27.8 MHz cavity round-trip frequency. Strong optoacoustic interactions in this PCF-based, Tm-doped fiber laser ensure stable and repeatable gigahertz-rate pulse train generation at 1.85 μm wavelength, with a high supermode noise suppression ratio and low pulse timing jitter...
October 1, 2016: Optics Letters
Ke Hu, Hui-Chun Wu
We study x-ray production by coherent nonlinear Thomson scattering of few-cycle laser pulses from relativistic electron sheets. For an electron sheet thicker than the wavelength of the x-ray, the scattering efficiency is found to increase by two orders of magnitude for single-cycle laser pulses, as compared with longer pulses. This enhancement is attributed to the suppression of the destructive interference during the scattering process, as well as the frequency downshift related to the ultrabroad spectra of single-cycle pulses...
October 1, 2016: Optics Letters
So Eun Park, Sang Seok Kim, Chul Woo Kim, Young Her
No abstract text is available yet for this article.
October 2016: Annals of Dermatology
Muath Nairat, Vadim V Lozovoy, Marcos Dantus
While the interaction of atoms in strong fields is well understood, the same cannot be said about molecules. We consider how dissociative ionization of molecules depends on the quality of the femtosecond laser pulses, in particular, the presence of third- and fourth-order dispersion. We find that high-order dispersion (HOD) unexpectedly results in order-of-magnitude enhanced ion yields, along with the factor of three greater kinetic energy release compared to transform-limited pulses with equal peak intensities...
October 16, 2016: Journal of Physical Chemistry. A
C Neuville, C Baccou, A Debayle, P-E Masson-Laborde, S Hüller, M Casanova, D Marion, P Loiseau, K Glize, C Labaune, S Depierreux
Amplification of a picosecond pulse beam by a lower intensity nanosecond pulse beam was experimentally observed in a flowing plasma. Modifications of intensity distributions in beam focal spots due to nonhomogeneous energy transfer and its transient regime were investigated. The mean transferred power reached 57% of the incident power of the nanosecond pulse beam. An imaging diagnostic allowed the intensity profile of the picosecond pulse beam to be determined, bringing to evidence the spatial nonuniformity of energy transfer in the amplified beam...
September 30, 2016: Physical Review Letters
T M Ostermayr, D Haffa, P Hilz, V Pauw, K Allinger, K-U Bamberg, P Böhl, C Bömer, P R Bolton, F Deutschmann, T Ditmire, M E Donovan, G Dyer, E Gaul, J Gordon, B M Hegelich, D Kiefer, C Klier, C Kreuzer, M Martinez, E McCary, A R Meadows, N Moschüring, T Rösch, H Ruhl, M Spinks, C Wagner, J Schreiber
We report on experiments irradiating isolated plastic spheres with a peak laser intensity of 2-3×10^{20}Wcm^{-2}. With a laser focal spot size of 10 μm full width half maximum (FWHM) the sphere diameter was varied between 520 nm and 19.3 μm. Maximum proton energies of ∼25 MeV are achieved for targets matching the focal spot size of 10 μm in diameter or being slightly smaller. For smaller spheres the kinetic energy distributions of protons become nonmonotonic, indicating a change in the accelerating mechanism from ambipolar expansion towards a regime dominated by effects caused by Coulomb repulsion of ions...
September 2016: Physical Review. E
Yechiel Frank, Arie Zigler, Zohar Henis
The atomic kinetics of solid density low-Z material under an intense oscillating laser field is presented. The transient behavior of the average ionization and the heating mechanism is analyzed. Temporal oscillations in excited configurations populations caused by the laser field oscillations are demonstrated. These phenomena present a method for creating short, 1-100 fs, monochromatic but incoherent x-ray pulses and for measuring basic atomic rates.
September 2016: Physical Review. E
Z Jin, H B Zhuo, T Nakazawa, J H Shin, S Wakamatsu, N Yugami, T Hosokai, D B Zou, M Y Yu, Z M Sheng, R Kodama
Radially polarized intense terahertz (THz) radiation behind a thin foil irradiated by ultrahigh-contrast ultrashort relativistic laser pulse is recorded by a single-shot THz time-domain spectroscopy system. As the thickness of the target is reduced from 30 to 2 µm, the duration of the THz emission increases from 5 to over 20 ps and the radiation energy increases dramatically, reaching ∼10.5mJ per pulse, corresponding to a laser-to-THz radiation energy conversion efficiency of 1.7%. The efficient THz emission can be attributed to reflection (deceleration and acceleration) of the laser-driven hot electrons by the target-rear sheath electric field...
September 2016: Physical Review. E
Adam Michael Scheer, Arkke J Eskola, David L Osborn, Leonid Sheps, Craig Allen Taatjes
The pulsed photolytic chlorine-initiated oxidation of diethyl ketone [DEK; (CH3CH2)2C=O], 2,2,4,4-d4-DEK [d4-DEK; (CH3CD2)2C=O] and 1,1,1,5,5,5-d6-DEK [d6-DEK; (CD3CH2)2C=O] is studied at 8 Torr and 1 - 2 atm and from 400 - 625 K. Cl atoms produced by laser photolysis react with diethyl ketone to form either primary (3-pentan-on-1-yl, RP) or secondary (3-pentan-on-2-yl, RS¬¬) radicals, which in turn react with O2. Multiplexed time of flight mass spectrometry, coupled to either a hydrogen discharge lamp or tunable synchrotron photoionizing radiation, is used to detect products as a function of mass, time and photon energy...
October 11, 2016: Journal of Physical Chemistry. A
Seunghwoi Han, Hyunwoong Kim, Yong Woo Kim, Young-Jin Kim, Seungchul Kim, In-Yong Park, Seung-Woo Kim
Plasmonic high-harmonic generation (HHG) drew attention as a means of producing coherent extreme ultraviolet (EUV) radiation by taking advantage of field enhancement occurring in metallic nanostructures. Here a metal-sapphire nanostructure is devised to provide a solid tip as the HHG emitter, replacing commonly used gaseous atoms. The fabricated solid tip is made of monocrystalline sapphire surrounded by a gold thin-film layer, and intended to produce EUV harmonics by the inter- and intra-band oscillations of electrons driven by the incident laser...
October 10, 2016: Nature Communications
V M Malkin, N J Fisch
Powerful incoherent laser pulses can propagate in focusing Kerr media much longer distances than can coherent pulses, due to the fast phase mixing that prevents transverse filamentation. This distance is limited by 4-wave scattering, which accumulates waves at small transverse wave numbers, where phase mixing is too slow to retain the incoherence and thus prevent the filamentation. However, we identify how this theoretical limit can be overcome by countering this accumulation through transverse heating of the pulse by random fluctuations of the refractive index...
September 23, 2016: Physical Review Letters
S Eckart, M Richter, M Kunitski, A Hartung, J Rist, K Henrichs, N Schlott, H Kang, T Bauer, H Sann, L Ph H Schmidt, M Schöffler, T Jahnke, R Dörner
We report on nonsequential double ionization of Ar by a laser pulse consisting of two counterrotating circularly polarized fields (390 and 780 nm). The double-ionization probability depends strongly on the relative intensity of the two fields and shows a kneelike structure as a function of intensity. We conclude that double ionization is driven by a beam of nearly monoenergetic recolliding electrons, which can be controlled in intensity and energy by the field parameters. The electron momentum distributions show the recolliding electron as well as a second electron which escapes from an intermediate excited state of Ar^{+}...
September 23, 2016: Physical Review Letters
Y Ishibashi, Y Inoue, T Asahi
We have investigated the excitation intensity dependence of the singlet fission in a crystalline rubrene by means of femtosecond transient absorption microspectroscopy. When a rubrene microcrystal was excited to higher energy levels than that of the lowest singlet excited (S1) state with a 397 nm femtosecond laser pulse, a triplet excited state was formed through two pathways of the singlet fission, i.e. the direct fission from higher vibrational levels of the S1 state with a time constant of 2.2 ps and the thermally activated fission from the S1 state in a few tens of ps...
October 5, 2016: Photochemical & Photobiological Sciences
S V Makarov, A N Tsypkin, T A Voytova, V A Milichko, I S Mukhin, A V Yulin, S E Putilin, M A Baranov, A E Krasnok, I A Morozov, P A Belov
The advantage of metasurfaces and nanostructures with a high nonlinear response is that they do not require phase matching, and the generated pulses are short in the time domain without additional pulse compression. However, the fabrication of large-scale planar structures by lithography-based methods is expensive, time consuming, and requires complicated preliminary simulations to obtain the most optimized geometry. Here, we propose a novel strategy for the self-assembled fabrication of large-scale resonant metasurfaces, where incident femtosecond laser pulses adjust the initial silicon films via specific surface deformation to be as resonant as possible for a given wavelength...
October 6, 2016: Nanoscale
Christos Boutopoulos, Adrien Dagallier, Maria Sansone, Andre-Pierre Blanchard-Dionne, Évelyne Lecavalier-Hurtubise, Étienne Boulais, Michel Meunier
Precise spatial and temporal control of pressure stimulation at the nanometer scale is essential for the fabrication and manipulation of nano-objects, and for exploring single-molecule behaviour of matter under extreme conditions. However, state-of-the-art nano-mechanical transducers require sophisticated driving hardware and are currently limited to moderate pressure regimes. Here we report a gold plasmonic bowtie (AuBT) nano-antennas array that can generate extreme pressure stimulus of ∼100 GPa in the ps (10(-12) s) time scale with sub-wavelength resolution upon irradiation with ultra-short laser pulses...
October 6, 2016: Nanoscale
Taotao Lu, Chengzhe Wang, Levi Lystrom, Chengkui Pei, Svetlana Kilina, Wenfang Sun
The synthesis and photophysics of four platinum(ii) bipyridine (bpy) bisacetylide complexes with different degrees of π-conjugation and an electron-donating diphenylamino (NPh2) or electron-withdrawing benzothiazolyl (BTZ) terminal substituent on the acetylide ligands are reported. The UV-vis absorption spectra of these complexes are composed of intense ligand-localized (1)π,π* transitions at 330-430 nm and broad, moderately strong ligand-to-ligand charge transfer/metal-to-ligand charge transfer ((1)LLCT/(1)MLCT) transitions at 430-530 nm...
October 7, 2016: Physical Chemistry Chemical Physics: PCCP
R Pompili, M P Anania, F Bisesto, M Botton, M Castellano, E Chiadroni, A Cianchi, A Curcio, M Ferrario, M Galletti, Z Henis, M Petrarca, E Schleifer, A Zigler
Highly energetic electrons are generated at the early phases of the interaction of short-pulse high-intensity lasers with solid targets. These escaping particles are identified as the essential core of picosecond-scale phenomena such as laser-based acceleration, surface manipulation, generation of intense magnetic fields and electromagnetic pulses. Increasing the number of the escaping electrons facilitate the late time processes in all cases. Up to now only indirect evidences of these important forerunners have been recorded, thus no detailed study of the governing mechanisms was possible...
October 7, 2016: Scientific Reports
R Alonso-Mori, K Asa, U Bergmann, A S Brewster, R Chatterjee, J K Cooper, H M Frei, F D Fuller, E Goggins, S Gul, H Fukuzawa, D Iablonskyi, M Ibrahim, T Katayama, T Kroll, Y Kumagai, B A McClure, J Messinger, K Motomura, K Nagaya, T Nishiyama, C Saracini, Y Sato, N K Sauter, D Sokaras, T Takanashi, T Togashi, K Ueda, W W Weare, T-C Weng, M Yabashi, V K Yachandra, I D Young, A Zouni, J F Kern, J Yano
The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures...
September 14, 2016: Faraday Discussions
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