scholarly journals The time-resolved hard X-ray diffraction endstation KMC-3 XPP at BESSY II

2021 ◽  
Vol 28 (3) ◽  
Author(s):  
Matthias Rössle ◽  
Wolfram Leitenberger ◽  
Matthias Reinhardt ◽  
Azize Koç ◽  
Jan Pudell ◽  
...  
Keyword(s):  
Storage Ring ◽  
Single Photon ◽  
Laser System ◽  
High Vacuum ◽  
Laser Pulses ◽  
Pixel Detector ◽  
X Ray Diffraction ◽  
Optical Pump ◽  
Time Resolved ◽  
X Ray

The time-resolved hard X-ray diffraction endstation KMC-3 XPP for optical pump/X-ray probe experiments at the electron storage ring BESSY II is dedicated to investigating the structural response of thin film samples and heterostructures after their excitation with ultrashort laser pulses and/or electric field pulses. It enables experiments with access to symmetric and asymmetric Bragg reflections via a four-circle diffractometer and it is possible to keep the sample in high vacuum and vary the sample temperature between ∼15 K and 350 K. The femtosecond laser system permanently installed at the beamline allows for optical excitation of the sample at 1028 nm. A non-linear optical setup enables the sample excitation also at 514 nm and 343 nm. A time-resolution of 17 ps is achieved with the `low-α' operation mode of the storage ring and an electronic variation of the delay between optical pump and hard X-ray probe pulse conveniently accesses picosecond to microsecond timescales. Direct time-resolved detection of the diffracted hard X-ray synchrotron pulses use a gated area pixel detector or a fast point detector in single photon counting mode. The range of experiments that are reliably conducted at the endstation and that detect structural dynamics of samples excited by laser pulses or electric fields are presented.

scholarly journals FemtoSpeX: a versatile optical pump–soft X-ray probe facility with 100 fs X-ray pulses of variable polarization

2014 ◽  
Vol 21 (5) ◽  
pp. 1090-1104 ◽  
Author(s):  
Karsten Holldack ◽  
Johannes Bahrdt ◽  
Andreas Balzer ◽  
Uwe Bovensiepen ◽  
Maria Brzhezinskaya ◽  
...  
Keyword(s):  
Laser System ◽  
X Ray Diffraction ◽  
Optical Pump ◽  
Time Resolved ◽  
Transient Phenomena ◽  
X Ray ◽  
User Facility ◽  
Average Flux ◽  
The Stability ◽  
Electron Storage Rings

Here the major upgrades of the femtoslicing facility at BESSY II (Khanet al., 2006) are reviewed, giving a tutorial on how elliptical-polarized ultrashort soft X-ray pulses from electron storage rings are generated at high repetition rates. Employing a 6 kHz femtosecond-laser system consisting of two amplifiers that are seeded by one Ti:Sa oscillator, the total average flux of photons of 100 fs duration (FWHM) has been increased by a factor of 120 to up to 106 photons s−1(0.1% bandwidth)−1on the sample in the range from 250 to 1400 eV. Thanks to a new beamline design, a factor of 20 enhanced flux and improvements of the stability together with the top-up mode of the accelerator have been achieved. The previously unavoidable problem of increased picosecond-background at higher repetition rates, caused by `halo' photons, has also been solved by hopping between different `camshaft' bunches in a dedicated fill pattern (`3+1 camshaft fill') of the storage ring. In addition to an increased X-ray performance at variable (linear and elliptical) polarization, the sample excitation in pump–probe experiments has been considerably extended using an optical parametric amplifier that supports the range from the near-UV to the far-IR regime. Dedicated endstations covering ultrafast magnetism experiments based on time-resolved X-ray circular dichroism have been either upgraded or, in the case of time-resolved resonant soft X-ray diffraction and reflection, newly constructed and adapted to femtoslicing requirements. Experiments at low temperatures down to 6 K and magnetic fields up to 0.5 T are supported. The FemtoSpeX facility is now operated as a 24 h user facility enabling a new class of experiments in ultrafast magnetism and in the field of transient phenomena and phase transitions in solids.

Subpicosecond X-ray diffraction study of laser-induced disorder dynamics above the damage threshold of organic solids

1999 ◽  
Vol 32 (5) ◽  
pp. 977-981 ◽  
Author(s):  
A. Rousse ◽  
C. Rischel ◽  
I. Uschmann ◽  
E. Förster ◽  
P. A. Albouy ◽  
...  
Keyword(s):  
Damage Threshold ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
X Ray Diffraction ◽  
Optical Pump ◽  
Time Resolved ◽  
Lb Films ◽  
X Ray ◽  
Langmuir Blodgett ◽  
Acid Phthalate

Ultrafast disordering in Langmuir–Blodgett (LB) films and TlAP (thallium acid phthalate) crystals has been investigated by optical-pump–X-ray-probe experiments using intense femtosecond laser pulses. A laser-produced plasma X-ray source at 7.12 Å wavelength is used to study atomic dynamics by subpicosecond time-resolved X-ray diffraction. It is found that a drop of the X-ray diffracted intensity appears with time constants from below 600 fs up to a few tens of picoseconds in LB films optically excited at laser fluxes from 1.8 to 27 J cm−2. This loss in the diffracted intensity is understood as a displacement of the diffracting atoms by ∼8 Å from their equilibrium position. The response of the TlAP crystal was significantly slower. The relation to the atomic structure of the materials is discussed.

scholarly journals First steps towards time-resolved 'in-house' X-ray diffraction experiments

2014 ◽  
Vol 70 (a1) ◽  
pp. C775-C775 ◽  
Author(s):  
Radoslaw Kaminski ◽  
Jason Benedict ◽  
Elzbieta Trzop ◽  
Katarzyna Jarzembska ◽  
Bertrand Fournier ◽  
...  
Keyword(s):  
Excited State ◽  
Time Resolution ◽  
Structural Changes ◽  
Laser Pulses ◽  
High Repetition Rate ◽  
X Ray Diffraction ◽  
Laboratory Equipment ◽  
Time Resolved ◽  
X Ray ◽  
Ligand Charge Transfer

High-intensity X-ray sources, such as synchrotrons or X-ray free electron lasers, providing up to 100 ps time-resolution allow for studying very short-lived excited electronic states in molecular crystals. Some recent examples constitute investigations of Rh...Rh bond shortening,[1] or metal-to-ligand charge transfer processes in CuI complexes.[2] Nevertheless, in cases in which the lifetime of excited state species exceeds 10 μs it is now possible, due to the dramatic increase in the brightness of X-ray sources and the sensitivity of detectors, to use laboratory equipment to explore structural changes upon excitation. Consequently, in this contribution we present detailed technical description of the 'in-house' X-ray diffraction setup allowing for the laser-pump X-ray-probe experiments within the time-resolution at the order of 10 μs or larger. The experimental setup consists of a modified Bruker Mo-rotating-anode diffractometer, coupled with the high-frequency Nd:YAG laser (λ = 355 nm). The required synchronization of the laser pulses and the X-ray beam is realized via the optical chopper mounted across the beam-path. Chopper and laser capabilities enable high-repetition-rate experiments reaching up to 100 kHz. In addition, the laser shutter is being directly controlled though the original diffractometer software, allowing for collection of the data in a similar manner as done at the synchrotron (alternating light-ON & light-OFF frames). The laser beam itself is split into two allowing for improved uniform light delivery onto the crystal specimen. The designed setup was tested on the chosen set of crystals exhibiting rather long-lived excited state, such as, the Cu2Br2L2 (L = C5H4N-NMe2) complex, for which the determined lifetime is about 100 μs at 90 K. The results shall be presented. Research is funded by the National Science Foundation (CHE1213223). KNJ is supported by the Polish Ministry of Science and Higher Education through the "Mobility Plus" program.

Picosecond X-ray Diffraction: System and Applications

1994 ◽  
Vol 38 ◽  
pp. 21-33
Author(s):  
I. V. Tomov ◽  
P. Chen ◽  
P. M. Rentzepis
Keyword(s):  
Heat Transport ◽  
Time Resolution ◽  
Laser Pulses ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Silicon Crystals ◽  
193 Nm ◽  
Gold Platinum

Abstract We report the development of a novel, pulsed x-ray diffraction system with picosecond time resolution. The system has been used to study the heat transport in gold, platinum and silicon crystals heated by 10 ps, 193 nm laser pulses. Further developments and applications of time resolved picosecond x-ray diffraction are discussed.

X-ray Diffraction Study of Laser-Material Interactions with an Ultrafast Table-Top X-ray Source

1997 ◽  
Vol 502 ◽  
Author(s):  
T. Guo ◽  
C. Rose-Petruck ◽  
R. X. Jimenez ◽  
J. A. Squier ◽  
B. C. Walker ◽  
...  
Keyword(s):  
Lattice Dynamics ◽  
Laser System ◽  
Laser Pulses ◽  
Femtosecond Laser Pulses ◽  
X Ray Diffraction ◽  
Diffraction Intensity ◽  
Laser Material ◽  
X Ray ◽  
Laser Illumination ◽  
Terawatt Laser

ABSTRACTX-ray diffraction, employing a table-top, laser-driven x-ray source, has been used to investigate laser-material interactions with simultaneous picosecond and subatomic range distance resolution. The x-ray source, consisting of a table-top terawatt laser system and a moving Cu wire target apparatus, generates ˜ 5 × 1010 photons (4π steradians s)−1 of Cu Kα radiation. The lattice dynamics of the (111) planes of GaAs single crystals has been studied after the crystal is exposed to intense femtosecond laser pulses. The diffraction results have yielded information about the timescale of the lattice dynamics in the picosecond range and an upper limit for the width of the xray pulses. Initial strain, defined as the percentage of lattice distortion resulted from the laser illumination, is as high as 0.25% and is followed by an exponential decay with a time constant of ˜ 150 ps. Increases in the diffraction intensity after the laser irradiation have also been observed, likely due to a transition from dynamic to kinematic diffraction associated with degradation of the crystal.

scholarly journals Experimental and numerical study of ultra-short laser-produced collimated Cu Kα X-ray source

2017 ◽  
Vol 35 (3) ◽  
pp. 442-449 ◽  
Author(s):  
R. Rathore ◽  
V. Arora ◽  
H. Singhal ◽  
T. Mandal ◽  
J.A. Chakera ◽  
...  
Keyword(s):  
Laser Intensity ◽  
Numerical Study ◽  
Low Cost ◽  
Laser Pulses ◽  
Photon Flux ◽  
X Rays ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Short Laser Pulses

AbstractKα X-ray sources generated from the interaction of ultra-short laser pulses with solids are compact and low-cost source of ultra-short quasi-monochromatic X-rays compared with synchrotron radiation source. Development of collimated ultra-short Kα X-ray source by the interaction of 45 fs Ti:sapphire laser pulse with Cu wire target is presented in this paper. A study of the Kα source with laser parameters such as energy and pulse duration was carried out. The observed Kα X-ray photon flux was ~2.7 × 108 photons/shot at the laser intensity of ~2.8 × 1017 W cm−2. A model was developed to analyze the observed results. The Kα radiation was coupled to a polycapillary collimator to generate a collimated low divergence (0.8 mrad) X-ray beam. Such sources are useful for time-resolved X-ray diffraction and imaging studies.

scholarly journals Unveiling the spatial distribution of molecular coherences at conical intersections by covariance X-ray diffraction signals

2021 ◽  
Vol 118 (22) ◽  
pp. e2105046118
Author(s):  
Stefano M. Cavaletto ◽  
Daniel Keefer ◽  
Jérémy R. Rouxel ◽  
Flavia Aleotti ◽  
Francesco Segatta ◽  
...  
Keyword(s):  
Spatial Distribution ◽  
Three Dimensional ◽  
Laser Pulses ◽  
Conical Intersection ◽  
Conical Intersections ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Diffraction Imaging ◽  
The Rich

The outcomes and timescales of molecular nonadiabatic dynamics are decisively impacted by the quantum coherences generated at localized molecular regions. In time-resolved X-ray diffraction imaging, these coherences create distinct signatures via inelastic photon scattering, but they are buried under much stronger background elastic features. Here, we exploit the rich dynamical information encoded in the inelastic patterns, which we reveal by frequency-dispersed covariance ultrafast powder X-ray diffraction of stochastic X-ray free-electron laser pulses. This is demonstrated for the photoisomerization of azobenzene involving the passage through a conical intersection, where the nuclear wave packet branches and explores different quantum pathways. Snapshots of the coherence dynamics are obtained at high frequency shifts, not accessible with conventional diffraction measurements. These provide access to the timing and to the confined spatial distribution of the valence electrons directly involved in the conical intersection passage. This study can be extended to full three-dimensional imaging of conical intersections with ultrafast X-ray and electron diffraction.

Generation of 1-10 Ps Hard X-Rav Pulses for Time Resolved X-Ray Diffraction

1995 ◽  
Vol 39 ◽  
pp. 95-102
Author(s):  
P. Chen ◽  
I.V. Tomov ◽  
P. M. Rentzepis
Keyword(s):  
Uv Radiation ◽  
Repetition Rate ◽  
Laser System ◽  
Experimental System ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Deep Uv ◽  
193 Nm

We present a further improvement of our experimental system for the generation of hard x-ray pulses in the range 1-10 ps, A laser system based on a cw mode locked Nd:YLF laser is utilized for the emission of deep UV pulses at 193 nm with duration 1.5 ps and repetition rate of 300 Hz, This UV radiation is used to pump an x-ray diode which produces CuKa x-ray pulses with a duration shorter than 10 ps at 300 Hz.

Evolution of laser-induced strain in a Ge crystal for the [111] and [100] directions probed by time-resolved X-ray diffraction

2021 ◽  
Vol 54 (6) ◽  
Author(s):  
Ranjana Rathore ◽  
Himanshu Singhal ◽  
Ajmal Ansari ◽  
Juzer Ali Chakera
Keyword(s):  
Propagation Velocity ◽  
Laser Excitation ◽  
Laser Pulses ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
Carrier Diffusion ◽  
X Ray ◽  
Strained Crystal ◽  
Different Depths ◽  
Silicon Based

Ultra-short laser-pulse-induced strain propagation in a Ge crystal is studied in the [111] and [100] directions using time-resolved X-ray diffraction (TXRD). The strain propagation velocity is derived by analysis of the TXRD signal from the strained crystal planes. Numerical integration of the Takagi–Taupin equations is performed using open source code, which provides a very simple approach to estimate the strain propagation velocity. The present method will be particularly useful for relatively broad spectral bandwidths and weak X-ray sources, where temporal oscillations in the diffracted X-ray intensity at the relevant phonon frequencies would not be visible. The two Bragg reflections of the Ge sample, viz. 111 and 400, give information on the propagation of strain for two different depths, as the X-ray extinction depths are different for these two reflections. The strain induced by femtosecond laser excitation has a propagation velocity comparable to the longitudinal acoustic velocity. The strain propagation velocity increases with increasing laser excitation fluence. This fluence dependence of the strain propagation velocity can be attributed to crystal heating by ambipolar carrier diffusion. Ge is a promising candidate for silicon-based optoelectronics, and this study will enhance the understanding of heat transport by carrier diffusion in Ge induced by ultra-fast laser pulses, which will assist in the design of optoelectronic devices.

Development of shock-dynamics study with synchrotron-based time-resolved X-ray diffraction using an Nd:glass laser system

2020 ◽  
Vol 27 (2) ◽  
pp. 371-377 ◽  
Author(s):  
Sota Takagi ◽  
Kouhei Ichiyanagi ◽  
Atsushi Kyono ◽  
Shunsuke Nozawa ◽  
Nobuaki Kawai ◽  
...  
Keyword(s):  
Strain Rate ◽  
Shock Compression ◽  
Dynamic Compression ◽  
Laser System ◽  
Target Position ◽  
Experimental System ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Nd:Glass Laser

The combination of high-power laser and synchrotron X-ray pulses allows us to observe material responses under shock compression and release states at the crystal structure on a nanosecond time scale. A higher-power Nd:glass laser system for laser shock experiments was installed as a shock driving source at the NW14A beamline of PF-AR, KEK, Japan. It had a maximum pulse energy of 16 J, a pulse duration of 12 ns and a flat-top intensity profile on the target position. The shock-induced deformation dynamics of polycrystalline aluminium was investigated using synchrotron-based time-resolved X-ray diffraction (XRD) under laser-induced shock. The shock pressure reached up to about 17 GPa with a strain rate of at least 4.6 × 107 s–1 and remained there for nanoseconds. The plastic deformation caused by the shock-wave loading led to crystallite fragmentation. The preferred orientation of the polycrystalline aluminium remained essentially unchanged during the shock compression and release processes in this strain rate. The newly established time-resolved XRD experimental system can provide useful information for understanding the complex dynamic compression and release behaviors.

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