issue contents
January 2021 issue
facility information
editorial
Open access
Introducing two new Main Editors of JSR.
research papers
Open access
An ensemble-averaged Wigner distribution is a useful tool for time–frequency analysis of simulated SASE FEL pulses. Here it is shown how to calculate its frequency-wise autocorrelation based on a set of measured single-shot SASE spectra.
Open access
The generation of THz radiation in the frequency range of 0.1 THz up to >10 THz by means of Cherenkov–wakefield radiation in dielectric lined tubes is discussed. Achievable power levels and pulse structures fulfill the needs of pump–probe type experiments at modern XFEL facilities. Cherenkov–wakefield radiators hence offer a simple, inexpensive and versatile option for the generation of THz radiation over a wide range of parameters.
A mid-infrared free-electron laser was applied to the structural analysis of biological fossils. Infrared microscopy and far-infrared spectroscopy following vibration mode selective irradiation clearly show the structural variation of fossilized inks from cephalopods.
Open access
This paper describes a short-pulse laser source based on post-compression via multi-pass spectral broadening of a 1030 nm burst-mode laser employed for FEL pump–probe experiments.
A new configuration for self-seeding free-electron lasers is proposed, operated under a high repetition rate which can strongly suppress the thermal effects on the monochromator and provides a narrow-bandwidth FEL pulse. Three-dimension time-dependent simulations have been performed to demonstrate this idea.
PHYSICS | FELS
Open access
XFEL radiation based on the stochastic SASE principle can be described by a low-dimensional configuration space. This space of pulse shapes can be sufficiently sampled before an imaging experiment. This approach is used to implement near-field holography of dynamic processes, demonstrated for the example of a micro-fluidic jet illuminated by the divergent wavefront emanating from a compound refractive lens nano-focus. Droplet formation in the break-up regime of the jet, as well as the hydrodynamic phenomena following plasma generation by an intense infrared laser pulse, can be imaged, based on flat-field corrected holograms and subsequent phase retrieval.
Open access
A 1.5 Å resolution crystal structure of bovine trypsin at room temperature has been determined using 150 fs X-ray diffraction snapshots at the FemtoMAX beamline of the MAX IV facility.
An extension of the currently established X-ray reflectivity theory is developed to include surfaces having two distinct surface components by considering the convolution of longer spatial wavelength surface slopes with the previously well understood surface roughness model.
The performance of various Mössbauer experiments in a rotating system with synchrotron radiation and with an ordinary source of resonant γ-quanta is analyzed.
Significant heat generation at a first-mirror chamber and light emission at a viewport were found at a soft X-ray beamline with an undulator source, which can be explained by photoelectrons from the mirror. It was confirmed that a photoelectron shield consisting of thin copper plates prevents both phenomena and improves the pressure of the vacuum chamber.
Thermo-mechanical and ray-tracing analysis of a high-heat-load monochromator in the horizontal scattering plane was performed, aiming to preserve a high quality of the X-ray beam in the vertical plane for downstream optics. Changing to the horizontal scattering plane leads to no significant loss in terms of photon throughput, and angular distortions of the reflected beam in the sagittal (vertical) plane are by an order of magnitude smaller than in the meridional (horizontal) one, with sagittal distortions being smaller than the typical vertical angular size of the beam source at the monochromator position.
Single-crystalline Ib diamonds with low nitrogen content have been grown and characterized by high-resolution rocking-curve imaging. Despite the presence of nitrogen, thin diamond plates possess high diffraction quality similar to that in type-IIa diamond crystals.
Absolute X-ray energy measurement based on a Bond diffractometer is demonstrated. This diffractometer uses a reference silicon single-crystal plate and a highly accurate angle encoder to measure the Bragg angle accurately.
Open access
An advanced X-ray polarimeter for nuclear resonant scattering experiments, which is now available for users at beamline P01 of the storage ring PETRA III, is reported. The new polarimeter provides a hitherto unachieved degree of polarization purity of 2 × 10−9 for the nuclear resonance of 57Fe.
Open access
A new type of double-crystal monochromator is proposed. It will make side-bounce beamlines energy tunable by adding two more rotations to a conventional double-crystal monochromator.
Open access
Characterization of the Percival 2Megapixel detector with soft X-rays is presented.
Open access
The layout and performance of a multi-analyser detector for high-resolution powder diffraction at an X-ray energy of 60 keV are described.
Open access
A custom sample chamber developed for synchrotron X-ray experiments conducted at varying temperatures combined with the application of electric fields is presented. The chamber features an exchangeable hemispherical dome and an xyz manipulator for electric contacting of the sample. The article describes heating and cooling capabilities, exemplary experiments and plans for future upgrades of the chamber.
The design of a data management system at HEPS, responsible for automating the organisation, transfer, storage, distribution and sharing of data produced from experiments, is described.
Open access
Aligned molecules, for example in polyimide foils, lead to small dichroism even far from resonances, which can be revealed by high-precision X-ray polarimetry.
The strain profile inside very low lattice-mismatched HgCdTe/CdZnTe multilayer stacks used in complex dual-band IR detector was successfully measured with the required strain resolution of 10−5. Combined with chemical-sensitive techniques, this approach allows correlation of lattice-mismatch, interface compositional gradient and strain while isolating specific layer contributions.
High-resolution (0.12 a.u.) Compton profiles of hexagonal Zn have been measured on the SPring-8 BL08W beamline. Experimental results were compared with previous Korringa–Kohn–Rostoker and the new density functional theory theoretical band structure calculations.
Absorption integrals and scattering factors are derived from a rigorous solution of the vector Helmholtz equations based on the boundary integral equations and Monte Carlo method. Using explicit formulae (in quadratures) the author finds the absorption and scattering intensity of one- and bi-periodic gratings and mirrors, which may have random roughnesses.
Hard X-ray nanodiffraction and k-means cluster analysis were performed to reveal the presence of two distinct phases in a nanopatterned ferroelectric sample.
Wide-angle X-ray scattering is applied to a Cm-doped borosilicate glass fitted in a Be container. Structure factors are extracted from 2D diffraction patterns. The data are discussed in relation to the medium-range glass structure.
By modifications of the interface of Cr/Ti multilayers using an ultra-thin carbon buffer layer at each interface, remarkable improvement of the soft X-ray reflectivity of the multilayers in the water window region has been achieved.
This work focuses on assessing the radiation damage induced by soft X-ray exposure of paraffin, a common soft-tissue embedding medium, deposited on two typical soft X-ray sample supports: ultralene and Si3N4 windows. The effects of soft X-ray radiation have been studied by FTIR microspectroscopy not only at different doses but also at different times after exposure out of a vacuum atmosphere, confirming that an oxidation process takes place.
Extended X-ray absorption fine-structure (EXAFS) investigations of Co69FexSi21–xB10 (x = 3, 5, 7) glassy ribbons performed at the Co K-edge are reported.
Open access
A general description of magnetic dichroism effects in X-ray absorption spectroscopy using a few fundamental spectra extracted from experimental measurements is provided. The accuracy of the procedure is investigated theoretically.
Open access
A high-throughput data-management workflow is demonstrated, using a Lambda detector and XSPA-500k, a novel 52 kHz frame rate 1024 × 512 pixelated detector with no gaps in the read-out modules.
Open access
In situ X-ray absorption studies of niobium at high temperatures in vacuum, dilute air and nitrogen atmospheres are reported.
An automatic 3D image registration method is implemented for correcting unanticipated sample deformation during nano-resolution spectro-tomography experiments. This method significantly improves the quality of the spatially resolved XANES spectra, which fingerprints the local chemistry.
An inclined geometry method has been applied to a Laue geometry setup for X-ray analyser-based phase-contrast imaging through rotation of the detector and object about the optical axis allowing this traditionally 1-D phase-sensitive phase-contrast method to possess 2-D phase sensitivity. Tomographic datasets were acquired over 360° of a multi-material phantom to reconstruct the real and imaginary parts of the refractive index of the phantom.
Open access
A lossy adaptive encoding scheme that can be implemented on a per-pixel basis in hybrid pixel array detectors is described. It is shown that this lossy compression scheme has no effect on X-ray ptychographic images even at low signal levels.
A novel monochromatic X-ray Bragg diffraction imaging approach is described to unravel the correlated defects and millimeter-scaled distortions in HgCdTe epilayers on CdZnTe substrates.
Open access
Broadband X-ray ptychography is developed based on the multi-wavelength reconstruction method and is systematically demonstrated in both simulation and experiment. In addition, a combined reconstruction approach is proposed to further increase the ptychographic imaging rate.
short communications
Open access
Beamline B21 at Diamond Light Source is a high-throughput beamline that focuses primarily on the fast measurement of solutions. Here 3D-printing is used to expand the versatility of sample states that can be measured on B21.
A high-speed rotation device for X-ray tomography with a temporal resolution of 10 ms is presented.
The implementation of synchrotron radiation X-ray microtomography for non-destructive visualization of the internal microstructure of a human cochlea inserted with a highly absorbing cochlear implant electrode array is presented.
beamlines
Open access
ROBL-II at ESRF provides four experimental stations to investigate actinides with X-ray absorption and emission spectroscopy, and with surface, high-resolution powder, and single-crystal X-ray diffractometry.
Open access
This paper describes a detailed simulation of the influence of optical imperfections in a multilayer Bragg mirror-based split-and-delay unit on the focused and unfocused beam profiles with relative time delays within the coherence time for hard X-ray pump/X-ray probe experiments at the European XFEL.
The design of a multi-crystal Johann-type spectrometer for X-ray emission spectroscopy is presented. Fundamental concepts and alignment procedure are described.
addenda and errata
Free
Corrections to equations and experimental results in the paper by Inoue et al. [(2019). J. Synchrotron Rad. 26, 2050–2054] are made.