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[show abstract]
[hide abstract]
ABSTRACT: With an eye toward extending optical wave-mixing techniques to the x-ray regime, we present the first experimental demonstration of a two-color x-ray free-electron laser at the Linac Coherent Light Source. We combine the emittance-spoiler technique with a magnetic chicane in the undulator section to control the pulse duration and relative delay between two intense x-ray pulses and we use differently tuned canted pole undulators such that the two pulses have different wavelengths as well. Two schemes are shown to produce two-color soft x-ray pulses with a wavelength separation up to ∼1.9% and a controllable relative delay up to 40 fs.
Physical Review Letters 03/2013; 110(13):134801. · 7.37 Impact Factor
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Y Ding,
F-J Decker,
P Emma,
C Feng,
C Field,
J Frisch,
Z Huang, J Krzywinski,
H Loos,
J Welch,
J Wu,
F Zhou
[show abstract]
[hide abstract]
ABSTRACT: We report the first measurements of x-ray single-pulse duration and two-pulse separation at the Linac Coherent Light Source using a cross-correlation technique involving x rays and electrons. An emittance-spoiling foil is adopted as a very simple and effective method to control the output x-ray pulse. A minimum pulse duration of about 3 fs full width at half maximum has been measured together with a controllable pulse separation (delay) between two pulses. This technique provides critical temporal diagnostics for x-ray experiments such as x-ray pump-probe studies.
Physical Review Letters 12/2012; 109(25):254802. · 7.37 Impact Factor
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B I Cho,
K Engelhorn,
S M Vinko,
H-K Chung,
O Ciricosta,
D S Rackstraw,
R W Falcone,
C R D Brown,
T Burian,
J Chalupský, [......],
J J Turner,
L Vysin,
T Wang,
B Wu,
U Zastrau,
D Zhu,
R W Lee,
B Nagler,
J S Wark,
P A Heimann
[show abstract]
[hide abstract]
ABSTRACT: The x-ray intensities made available by x-ray free electron lasers (FEL) open up new x-ray matter interaction channels not accessible with previous sources. We report here on the resonant generation of Kα emission, that is to say the production of copious Kα radiation by tuning the x-ray FEL pulse to photon energies below that of the K edge of a solid aluminum sample. The sequential absorption of multiple photons in the same atom during the 80 fs pulse, with photons creating L-shell holes and then one resonantly exciting a K-shell electron into one of these holes, opens up a channel for the Kα production, as well as the absorption of further photons. We demonstrate rich spectra of such channels, and investigate the emission produced by tuning the FEL energy to the K-L transitions of those highly charged ions that have transition energies below the K edge of the cold material. The spectra are sensitive to x-ray intensity dependent opacity effects, with ions containing L-shell holes readily reabsorbing the Kα radiation.
Physical Review Letters 12/2012; 109(24):245003. · 7.37 Impact Factor
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J. Gaudin,
O. Peyrusse,
J. Chalupský,
M. Toufarová,
L. Vyšín,
V. Hájková,
R. Sobierajski,
T. Burian,
Sh. Dastjani-Farahani,
A. Graf, [......],
R. A. London,
S. Moeller,
H. Sinn,
S. Schorb,
M. Störmer,
Th. Tschentscher,
V. Vorlíček,
H. Vu,
J. Bozek,
C. Bostedt
[show abstract]
[hide abstract]
ABSTRACT: We present the results of an experiment where amorphous carbon undergoes a phase transition induced by femtosecond 830 eV x-ray free-electron laser pulses. The phase transition threshold fluence is found to be 282 ± 11 mJ/cm2. Atomic force microscopy, photoelectron microscopy, and micro-Raman spectroscopy give experimental evidence for the phase transition in terms of a volume expansion, graphitization, and change of local order of the irradiated sample area. The interaction is modeled by an accurate time-dependent treatment of the ionization dynamics coupled to a two-temperature model. At the phase transition fluence threshold the free-electron density Ne is found to be at maximum 9 × 1020 cm−3 while the ion (atom) temperature is found to be 1050 K, e.g., above the crystallization activation temperature reported in the literature. This low ionization rate and high atom temperature suggest a thermally activated phase transition.
Phys. Rev. B. 07/2012; 86(2).
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W F Schlotter,
J J Turner,
M Rowen,
P Heimann,
M Holmes,
O Krupin,
M Messerschmidt,
S Moeller, J Krzywinski,
R Soufli, [......],
B Abbey,
K A Nugent,
H Sinn,
J Lüning,
S Schaffert,
S Eisebitt,
W-S Lee,
A Scherz,
A R Nilsson,
W Wurth
[show abstract]
[hide abstract]
ABSTRACT: The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480-2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study diverse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and laboratory astrophysics. Preliminary commissioning results are presented including the first soft x-ray single-shot energy spectrum from a free electron laser.
The Review of scientific instruments 04/2012; 83(4):043107. · 1.52 Impact Factor
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S M Vinko,
O Ciricosta,
B I Cho,
K Engelhorn,
H-K Chung,
C R D Brown,
T Burian,
J Chalupský,
R W Falcone,
C Graves, [......],
J J Turner,
L Vysin,
T Wang,
B Wu,
U Zastrau,
D Zhu,
R W Lee,
P A Heimann,
B Nagler,
J S Wark
[show abstract]
[hide abstract]
ABSTRACT: Matter with a high energy density (>10(5) joules per cm(3)) is prevalent throughout the Universe, being present in all types of stars and towards the centre of the giant planets; it is also relevant for inertial confinement fusion. Its thermodynamic and transport properties are challenging to measure, requiring the creation of sufficiently long-lived samples at homogeneous temperatures and densities. With the advent of the Linac Coherent Light Source (LCLS) X-ray laser, high-intensity radiation (>10(17) watts per cm(2), previously the domain of optical lasers) can be produced at X-ray wavelengths. The interaction of single atoms with such intense X-rays has recently been investigated. An understanding of the contrasting case of intense X-ray interaction with dense systems is important from a fundamental viewpoint and for applications. Here we report the experimental creation of a solid-density plasma at temperatures in excess of 10(6) kelvin on inertial-confinement timescales using an X-ray free-electron laser. We discuss the pertinent physics of the intense X-ray-matter interactions, and illustrate the importance of electron-ion collisions. Detailed simulations of the interaction process conducted with a radiative-collisional code show good qualitative agreement with the experimental results. We obtain insights into the evolution of the charge state distribution of the system, the electron density and temperature, and the timescales of collisional processes. Our results should inform future high-intensity X-ray experiments involving dense samples, such as X-ray diffractive imaging of biological systems, material science investigations, and the study of matter in extreme conditions.
Nature 02/2012; 482(7383):59-62. · 36.28 Impact Factor
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J. Gaudin,
J Chalupský,
M. Toufarová,
L. Vyšín,
V Hájková,
R. Sobierajski,
T. Burian,
Sh. Dastjani Farahani,
A. Graf,
M. Amati, [......],
R.A. London,
S. Moeller,
H. Sinn,
S. Schorb,
M. Störmer,
Th. Tschentscher,
V. Vorlíček,
H. Vu,
J. Bozek,
C. Bostedt
[show abstract]
[hide abstract]
ABSTRACT: We present the results of an experiment where amorphous carbon was irradiated
by femtosecond x-ray free electron laser pulses. The 830 eV laser pulses induce
a phase transition in the material which is characterized ex-situ. The phase
transition energy threshold is determined by measuring the surface of each
irradiated area using an optical Nomarski microscope. The threshold fluence is
found to be 282 +/- 11 mJ/cm^2, corresponding to an absorbed dose at the
surface of 131 +/-5 meV/atom. Atomic force microscopy measurements show volume
expansion of the irradiated sample area, suggesting a solid to solid phase
transition. Deeper insight into the phase transition is gained by using
scanning photoelectron microscopy and micro-Raman spectroscopy. Photoelectron
microscopy shows graphitization, i.e. modification from sp3 to sp2
hybridization, of the irradiated material. The micro-Raman spectra show the
appearance of local order, i.e. formation of graphite nanocrystals. Finally,
the nature of the phase transition is discussed, taking into account previous
theory and experimental results.
11/2011;
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Mina R Bionta,
H T Lemke,
J P Cryan,
J M Glownia,
C Bostedt,
M Cammarata,
J-C Castagna,
Y Ding,
D M Fritz,
A R Fry, J Krzywinski,
M Messerschmidt,
S Schorb,
M L Swiggers,
R N Coffee
[show abstract]
[hide abstract]
ABSTRACT: We present a new technique for measuring the relative delay between a soft x-ray FEL pulse and an optical laser that indicates a sub 25 fs RMS measurement error. An ultra-short x-ray pulse photo-ionizes a semiconductor (Si(3)N(4)) membrane and changes the optical transmission. An optical continuum pulse with a temporally chirped bandwidth spanning 630 nm-710 nm interacts with the membrane such that the timing of the x-ray pulse can be determined from the onset of the spectral modulation of the transmitted optical pulse. This experiment demonstrates a nearly in situ single-shot measurement of the x-ray pulse arrival time relative to the ultra-short optical pulse.
Optics Express 10/2011; 19(22):21855-65. · 3.59 Impact Factor
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I A Vartanyants,
A Singer,
A P Mancuso,
O M Yefanov,
A Sakdinawat,
Y Liu,
E Bang,
G J Williams,
G Cadenazzi,
B Abbey, [......],
V Joshi, J Krzywinski,
R Soufli,
M Fernandez-Perea,
S Hau-Riege,
A G Peele,
Y Feng,
O Krupin,
S Moeller,
W Wurth
[show abstract]
[hide abstract]
ABSTRACT: Measurements of the spatial and temporal coherence of single, femtosecond x-ray pulses generated by the first hard x-ray free-electron laser, the Linac Coherent Light Source, are presented. Single-shot measurements were performed at 780 eV x-ray photon energy using apertures containing double pinholes in "diffract-and-destroy" mode. We determined a coherence length of 17 μm in the vertical direction, which is approximately the size of the focused Linac Coherent Light Source beam in the same direction. The analysis of the diffraction patterns produced by the pinholes with the largest separation yields an estimate of the temporal coherence time of 0.55 fs. We find that the total degree of transverse coherence is 56% and that the x-ray pulses are adequately described by two transverse coherent modes in each direction. This leads us to the conclusion that 78% of the total power is contained in the dominant mode.
Physical Review Letters 09/2011; 107(14):144801. · 7.37 Impact Factor
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D Ratner,
A Brachmann,
F J Decker,
Y Ding,
D Dowell,
P Emma,
A Fisher,
J Frisch,
S Gilevich,
Z Huang, [......],
R Iverson, J Krzywinski,
H Loos,
M Messerschmidt,
H D Nuhn,
T Smith,
J Turner,
J Welch,
W White,
J Wu
[show abstract]
[hide abstract]
ABSTRACT: The linac coherent light source (LCLS) is a self-amplified spontaneous emission (SASE) free-electron laser (FEL) operating at fundamental photon energies from 0.5 to 10 keV. Characterization of the higher harmonics present in the FEL beam is important to users, for whom harder x rays can either extend the useful operating wavelength range or increase experimental backgrounds. We present measurements of the power in both the second and third harmonics, and compare the results to expectations from simulations. We also present studies of the transport of harmonics to the users, and the harmonic power as a function of electron beam quality.
Physical Review Special Topics - Accelerators and Beams 06/2011; 14. · 1.52 Impact Factor
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E Galtier,
F B Rosmej,
T Dzelzainis,
D Riley,
F Y Khattak,
P Heimann,
R W Lee,
A J Nelson,
S M Vinko,
T Whitcher, [......],
S Toleikis,
R R Fäustlin,
R Sobierajski,
M Jurek,
L Juha,
J Chalupsky,
V Hajkova,
M Kozlova, J Krzywinski,
B Nagler
[show abstract]
[hide abstract]
ABSTRACT: We have studied a solid-to-plasma transition by irradiating Al foils with the FLASH free electron laser at intensities up to 10(16) W/cm(2). Intense XUV self-emission shows spectral features that are consistent with emission from regions of high density, which go beyond single inner-shell photoionization of solids. Characteristic features of intrashell transitions allowed us to identify Auger heating of the electrons in the conduction band occurring immediately after the absorption of the XUV laser energy as the dominant mechanism. A simple model of a multicharge state inverse Auger effect is proposed to explain the target emission when the conduction band at solid density becomes more atomiclike as energy is transferred from the electrons to the ions. This allows one to determine, independent of plasma simulations, the electron temperature and density just after the decay of crystalline order and to characterize the early time evolution.
Physical Review Letters 04/2011; 106(16):164801. · 7.37 Impact Factor
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J Andreasson,
B Iwan,
A Andrejczuk,
E Abreu,
M Bergh,
C Caleman,
A J Nelson,
S Bajt,
J Chalupsky,
H N Chapman, [......],
G K Pálsson,
W Singer,
M M Seibert,
R Sobierajski,
S Toleikis,
T Tschentscher,
S M Vinko,
R W Lee,
J Hajdu,
N Tîmneanu
[show abstract]
[hide abstract]
ABSTRACT: Studies of materials under extreme conditions have relevance to a broad area of research, including planetary physics, fusion research, materials science, and structural biology with x-ray lasers. We study such extreme conditions and experimentally probe the interaction between ultrashort soft x-ray pulses and solid targets (metals and their deuterides) at the FLASH free-electron laser where power densities exceeding 10(17) W/cm(2) were reached. Time-of-flight ion spectrometry and crater analysis were used to characterize the interaction. The results show the onset of saturation in the ablation process at power densities above 10(16) W/cm(2). This effect can be linked to a transiently induced x-ray transparency in the solid by the femtosecond x-ray pulse at high power densities. The measured kinetic energies of protons and deuterons ejected from the surface reach several keV and concur with predictions from plasma-expansion models. Simulations of the interactions were performed with a nonlocal thermodynamic equilibrium code with radiation transfer. These calculations return critical depths similar to the observed crater depths and capture the transient surface transparency at higher power densities.
Physical Review E 01/2011; 83(1 Pt 2):016403. · 2.26 Impact Factor
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R Sobierajski,
S Bruijn,
A R Khorsand,
E Louis,
R W E van de Kruijs,
T Burian,
J Chalupsky,
J Cihelka,
A Gleeson,
J Grzonka, [......], J Krzywinski,
R London,
J B Pelka,
T Płociński,
M Rasiński,
K Tiedtke,
S Toleikis,
L Vysin,
H Wabnitz,
F Bijkerk
[show abstract]
[hide abstract]
ABSTRACT: We investigated the damage mechanism of MoN/SiN multilayer XUV optics under two extreme conditions: thermal annealing and irradiation with single shot intense XUV pulses from the free-electron laser facility in Hamburg - FLASH. The damage was studied "post-mortem" by means of X-ray diffraction, interference-polarizing optical microscopy, atomic force microscopy, and scanning transmission electron microscopy. Although the timescale of the damage processes and the damage threshold temperatures were different (in the case of annealing it was the dissociation temperature of Mo2N and in the case of XUV irradiation it was the melting temperature of MoN) the main damage mechanism is very similar: molecular dissociation and the formation of N2, leading to bubbles inside the multilayer structure.
Optics Express 01/2011; 19(1):193-205. · 3.59 Impact Factor
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C David,
S Gorelick,
S Rutishauser, J Krzywinski,
J Vila-Comamala,
V A Guzenko,
O Bunk,
E Färm,
M Ritala,
M Cammarata,
D M Fritz,
R Barrett,
L Samoylova,
J Grünert,
H Sinn
[show abstract]
[hide abstract]
ABSTRACT: A growing number of X-ray sources based on the free-electron laser (XFEL) principle are presently under construction or have recently started operation. The intense, ultrashort pulses of these sources will enable new insights in many different fields of science. A key problem is to provide x-ray optical elements capable of collecting the largest possible fraction of the radiation and to focus into the smallest possible focus. As a key step towards this goal, we demonstrate here the first nanofocusing of hard XFEL pulses. We developed diamond based Fresnel zone plates capable of withstanding the full beam of the world's most powerful x-ray laser. Using an imprint technique, we measured the focal spot size, which was limited to 320 nm FWHM by the spectral band width of the source. A peak power density in the focal spot of 4×10(17)W/cm(2) was obtained at 70 fs pulse length.
Scientific Reports 01/2011; 1:57.
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J Chalupský, J Krzywinski,
L Juha,
V Hájková,
J Cihelka,
T Burian,
L Vysín,
J Gaudin,
A Gleeson,
M Jurek,
A R Khorsand,
D Klinger,
H Wabnitz,
R Sobierajski,
M Störmer,
K Tiedtke,
S Toleikis
[show abstract]
[hide abstract]
ABSTRACT: We present a new technique for the characterization of non-Gaussian laser beams which cannot be described by an analytical formula. As a generalization of the beam spot area we apply and refine the definition of so called effective area (A(eff)) [1] in order to avoid using the full-width at half maximum (FWHM) parameter which is inappropriate for non-Gaussian beams. Furthermore, we demonstrate a practical utilization of our technique for a femtosecond soft X-ray free-electron laser. The ablative imprints in poly(methyl methacrylate) - PMMA and amorphous carbon (a-C) are used to characterize the spatial beam profile and to determine the effective area. Two procedures of the effective area determination are presented in this work. An F-scan method, newly developed in this paper, appears to be a good candidate for the spatial beam diagnostics applicable to lasers of various kinds.
Optics Express 12/2010; 18(26):27836-45. · 3.59 Impact Factor
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S P Hau-Riege,
R A London,
A Graf,
S L Baker,
R Soufli,
R Sobierajski,
T Burian,
J Chalupsky,
L Juha,
J Gaudin, J Krzywinski,
S Moeller,
M Messerschmidt,
J Bozek,
C Bostedt
[show abstract]
[hide abstract]
ABSTRACT: Materials used for hard x-ray-free-electron laser (XFEL) optics must withstand high-intensity x-ray pulses. The advent of the Linac Coherent Light Source has enabled us to expose candidate optical materials, such as bulk B4C and SiC films, to 0.83 keV XFEL pulses with pulse energies between 1 μJ and 2 mJ to determine short-pulse hard x-ray damage thresholds. The fluence required for the onset of damage for single pulses is around the melt fluence and slightly lower for multiple pulses. We observed strong mechanical cracking in the materials, which may be due to the larger penetration depths of the hard x-rays.
Optics Express 11/2010; 18(23):23933-8. · 3.59 Impact Factor
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F B Rosmej,
E Galtier,
D Riley,
T Dzelzainis,
P Heinmann,
F Y Khattak,
R W Lee,
B Nagler,
A Nelson,
T Tschentscher, [......],
R Fäustlin,
R Soberierski,
L Juha,
M Fajardo,
J S Wark,
J Chalupsky,
V Hajkova, J Krzywinski,
M Jurek,
M Kozlova
[show abstract]
[hide abstract]
ABSTRACT: Aluminium targets were irradiated with 92 eV radiation from FLASH Free Electron Laser at DESY at intensities up to 1017 W/cm2 by focussing the beam on target down to a spot size of ~1 μm by means of a parabolic mirror. High resolution XUV spectroscopy was used to identify aluminium emission from complex hole-states. Simulations carried out with the MARIA code show that the emission characterizes the electron heating in the transition phase solid-atomic. The analysis allows constructing a simple model of electron heating via Auger electrons.
Journal of Physics Conference Series 09/2010; 244(4):042028.
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S M Vinko,
U Zastrau,
S Mazevet,
J Andreasson,
S Bajt,
T Burian,
J Chalupsky,
H N Chapman,
J Cihelka,
D Doria, [......],
R Sobierajski,
F Tavella,
R Thiele,
J Tiggesbäumker,
S Toleikis,
T Tschentscher,
L Vysin,
T J Whitcher,
S White,
J S Wark
[show abstract]
[hide abstract]
ABSTRACT: By use of high intensity XUV radiation from the FLASH free-electron laser at DESY, we have created highly excited exotic states of matter in solid-density aluminum samples. The XUV intensity is sufficiently high to excite an inner-shell electron from a large fraction of the atoms in the focal region. We show that soft-x-ray emission spectroscopy measurements reveal the electronic temperature and density of this highly excited system immediately after the excitation pulse, with detailed calculations of the electronic structure, based on finite-temperature density functional theory, in good agreement with the experimental results.
Physical Review Letters 06/2010; 104(22):225001. · 7.37 Impact Factor
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A R Khorsand,
R Sobierajski,
E Louis,
S Bruijn,
E D van Hattum,
R W E van de Kruijs,
M Jurek,
D Klinger,
J B Pelka,
L Juha, [......],
H Wabnitz,
K Tiedtke,
K Sokolowski-Tinten,
U Shymanovich, J Krzywinski,
S Hau-Riege,
R London,
A Gleeson,
E M Gullikson,
F Bijkerk
[show abstract]
[hide abstract]
ABSTRACT: We investigated single shot damage of Mo/Si multilayer coatings exposed to the intense fs XUV radiation at the Free-electron LASer facility in Hamburg - FLASH. The interaction process was studied in situ by XUV reflectometry, time resolved optical microscopy, and "post-mortem" by interference-polarizing optical microscopy (with Nomarski contrast), atomic force microscopy, and scanning transmission electron microcopy. An ultrafast molybdenum silicide formation due to enhanced atomic diffusion in melted silicon has been determined to be the key process in the damage mechanism. The influence of the energy diffusion on the damage process was estimated. The results are of significance for the design of multilayer optics for a new generation of pulsed (from atto- to nanosecond) XUV sources.
Optics Express 01/2010; 18(2):700-12. · 3.59 Impact Factor
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A J Nelson,
S Toleikis,
H Chapman,
S Bajt, J Krzywinski,
J Chalupsky,
L Juha,
J Cihelka,
V Hajkova,
L Vysin, [......],
J Pelka,
B Iwan,
J Andreasson,
N Timneanu,
M Fajardo,
J S Wark,
D Riley,
T Tschentscher,
J Hajdu,
R W Lee
[show abstract]
[hide abstract]
ABSTRACT: We have focused a beam (BL3) of FLASH (Free-electron LASer in Hamburg: lambda = 13.5 nm, pulse length 15 fs, pulse energy 10-40 microJ, 5 Hz) using a fine polished off-axis parabola having a focal length of 270 mm and coated with a Mo/Si multilayer with an initial reflectivity of 67% at 13.5 nm. The OAP was mounted and aligned with a picomotor controlled six-axis gimbal. Beam imprints on poly(methyl methacrylate) - PMMA were used to measure focus and the focused beam was used to create isochoric heating of various slab targets. Results show the focal spot has a diameter of < or =1 microm. Observations were correlated with simulations of best focus to provide further relevant information.
Optics Express 09/2009; 17(20):18271-8. · 3.59 Impact Factor
