scholarly journals Progress in HAXPES performance combining full-field k-imaging with time-of-flight recording

2019 ◽  
Vol 26 (6) ◽  
pp. 1996-2012 ◽  
Author(s):  
K. Medjanik ◽  
S. V. Babenkov ◽  
S. Chernov ◽  
D. Vasilyev ◽  
B. Schönhense ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Time Of Flight ◽  
High Energy ◽  
Objective Lens ◽  
X Rays ◽  
Full Field ◽  
X Ray ◽  
Alternative Approach ◽  
Field Imaging ◽  
Phase Differences

An alternative approach to hard-X-ray photoelectron spectroscopy (HAXPES) has been established. The instrumental key feature is an increase of the dimensionality of the recording scheme from 2D to 3D. A high-energy momentum microscope detects electrons with initial kinetic energies up to 8 keV with a k-resolution of 0.025 Å−1, equivalent to an angular resolution of 0.034°. A special objective lens with k-space acceptance up to 25 Å−1 allows for simultaneous full-field imaging of many Brillouin zones. Combined with time-of-flight (ToF) parallel energy recording this yields maximum parallelization. Thanks to the high brilliance (1013 hν s−1 in a spot of <20 µm diameter) of beamline P22 at PETRA III (Hamburg, Germany), the microscope set a benchmark in HAXPES recording speed, i.e. several million counts per second for core-level signals and one million for d-bands of transition metals. The concept of tomographic k-space mapping established using soft X-rays works equally well in the hard X-ray range. Sharp valence band k-patterns of Re, collected at an excitation energy of 6 keV, correspond to direct transitions to the 28th repeated Brillouin zone. Measured total energy resolutions (photon bandwidth plus ToF-resolution) are 62 meV and 180 meV FWHM at 5.977 keV for monochromator crystals Si(333) and Si(311) and 450 meV at 4.0 keV for Si(111). Hard X-ray photoelectron diffraction (hXPD) patterns with rich fine structure are recorded within minutes. The short photoelectron wavelength (10% of the interatomic distance) `amplifies' phase differences, making full-field hXPD a sensitive structural tool.

scholarly journals Phase-Contrast and Dark-Field Imaging

2018 ◽  
Vol 4 (10) ◽  
pp. 113
Author(s):  
Simon Zabler
Keyword(s):  
Phase Contrast ◽  
Dark Field ◽  
X Rays ◽  
Reconstruction Algorithms ◽  
Contrast Imaging ◽  
Full Field ◽  
X Ray ◽  
Dark Field Imaging ◽  
Contrast Mechanisms ◽  
Field Imaging

Very early, in 1896, Wilhelm Conrad Röntgen, the founding father of X-rays, attempted to measure diffraction and refraction by this new kind of radiation, in vain. Only 70 years later, these effects were measured by Ulrich Bonse and Michael Hart who used them to make full-field images of biological specimen, coining the term phase-contrast imaging. Yet, another 30 years passed until the Talbot effect was rediscovered for X-radiation, giving rise to a micrograting based interferometer, replacing the Bonse–Hart interferometer, which relied on a set of four Laue-crystals for beam splitting and interference. By merging the Lau-interferometer with this Talbot-interferometer, another ten years later, measuring X-ray refraction and X-ray scattering full-field and in cm-sized objects (as Röntgen had attempted 110 years earlier) became feasible in every X-ray laboratory around the world. Today, now that another twelve years have passed and we are approaching the 125th jubilee of Röntgen’s discovery, neither Laue-crystals nor microgratings are a necessity for sensing refraction and scattering by X-rays. Cardboard, steel wool, and sandpaper are sufficient for extracting these contrasts from transmission images, using the latest image reconstruction algorithms. This advancement and the ever rising number of applications for phase-contrast and dark-field imaging prove to what degree our understanding of imaging physics as well as signal processing have advanced since the advent of X-ray physics, in particular during the past two decades. The discovery of the electron, as well as the development of electron imaging technology, has accompanied X-ray physics closely along its path, both modalities exploring the applications of new dark-field contrast mechanisms these days. Materials science, life science, archeology, non-destructive testing, and medicine are the key faculties which have already integrated these new imaging devices, using their contrast mechanisms in full. This special issue “Phase-Contrast and Dark-field Imaging” gives us a broad yet very to-the-point glimpse of research and development which are currently taking place in this very active field. We find reviews, applications reports, and methodological papers of very high quality from various groups, most of which operate X-ray scanners which comprise these new imaging modalities.

Influence of Tilt Angle on Hole Count and Secondary Fluorescence in x-ray Microanalysis

1990 ◽  
Vol 48 (2) ◽  
pp. 462-463
Author(s):  
E. A. Kenik ◽  
J. Bentley
Keyword(s):  
Tilt Angle ◽  
High Energy ◽  
Primary Electron ◽  
Objective Lens ◽  
X Rays ◽  
Bremsstrahlung Radiation ◽  
X Ray ◽  
Backscattered Electrons ◽  
The Magnetic Field ◽  
Secondary Fluorescence

The spatial resolution and accuracy of X-ray microanalysis in an analytical electron microscope (AEM) are limited by a variety of factors, two of which are the hole count and secondary fluorescence. The hole count arises from uncollimated radiation, either electrons or X rays, which excites areas of the specimen other than that excited by the primary electron beam. This can result in X-ray generation even when the probe does not hit the specimen; hence the name hole count. Secondary fluorescence deals with X-ray generation resulting from radiation produced by the interaction of the incident probe with the specimen. This radiation may be either backscattered electrons spiraling in the magnetic field of the objective lens or high energy X rays, particularly forward-peaked bremsstrahlung radiation. As the interaction of both the uncollimated radiation and the secondary radiation with the specimen can be influenced by the tilt angle of the specimen, the variation of the hole count and secondary fluorescence with specimen tilt was investigated.

scholarly journals The GALAXIES inelastic hard X-ray scattering end-station at Synchrotron SOLEIL

2019 ◽  
Vol 26 (1) ◽  
pp. 263-271 ◽  
Author(s):  
J. M. Ablett ◽  
D. Prieur ◽  
D. Céolin ◽  
B. Lassalle-Kaiser ◽  
B. Lebert ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Polarized Light ◽  
Research Direction ◽  
High Energy ◽  
High Energy Resolution ◽  
X Rays ◽  
Circularly Polarized Light ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

GALAXIES is an in-vacuum undulator hard X-ray micro-focused beamline dedicated to the study of the electronic structure of materials with high energy resolution using both photoelectron spectroscopy and inelastic X-ray scattering and under both non-resonant (NR-IXS) and resonant (RIXS) conditions. Due to the penetrating power of hard X-rays and the `photon-in/photon-out' technique, the sample environment is not a limitation. Materials under extreme conditions, for example in diamond anvil cells or catalysis chambers, thus constitute a major research direction. Here, the design and performance of the inelastic X-ray scattering end-station that operates in the energy range from ∼4 keV up to 12 keV is reported, and its capabilities are highlighted using a selection of data taken from recently performed experiments. The ability to scan `on the fly' the incident and scattered/emitted X-ray energies, and the sample position enables fast data collection and high experimental throughput. A diamond X-ray transmission phase retarder, which can be used to generate circularly polarized light, will also be discussed in the light of the recent RIXS–MCD approach.

High-energy X-ray photoelectron spectroscopy with new monochromatised Cu Kα1 X-rays; characteristics, capabilities and limitations

2006 ◽  
Vol 38 (4) ◽  
pp. 703-706 ◽  
Author(s):  
N. Moslemzadeh ◽  
G. Beamson ◽  
S. R. Haines ◽  
P. Tsakiropoulos ◽  
J. F. Watts ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Rays ◽  
X Ray

scholarly journals Translative lens-based full-field coherent X-ray imaging

2020 ◽  
Vol 27 (1) ◽  
pp. 119-126
Author(s):  
Carsten Detlefs ◽  
Mario Alejandro Beltran ◽  
Jean-Pierre Guigay ◽  
Hugh Simons
Keyword(s):  
Numerical Aperture ◽  
Objective Lens ◽  
X Rays ◽  
Resolution Limit ◽  
Radiation Dose Rate ◽  
Full Field ◽  
X Ray ◽  
X Ray Imaging ◽  
Imaging Approach ◽  
Potential Benefits

A full-field coherent imaging approach suitable for hard X-rays based on a classical (i.e. Galilean) X-ray microscope is described. The method combines a series of low-resolution images acquired at different transverse lens positions into a single high-resolution image, overcoming the spatial resolution limit set by the numerical aperture of the objective lens. The optical principles of the approach are described, the successful reconstruction of simulated phantom data is demonstrated, and aspects of the reconstruction are discussed. The authors believe that this approach offers some potential benefits over conventional scanning X-ray ptychography in terms of spatial bandwidth and radiation dose rate.

Beryllium parabolic refractive X-ray lenses for full field imaging and scanning microscopy with hard X-rays

2003 ◽  
Vol 104 ◽  
pp. 221-221
Author(s):  
B. Lengeler ◽  
C. G. Schroer ◽  
M. Kuhlmann ◽  
B. Benner ◽  
T. F. Günzler ◽  
...  
Keyword(s):  
Scanning Microscopy ◽  
X Rays ◽  
Full Field ◽  
X Ray ◽  
Field Imaging

The Basic Physical Principles of Ion, Electron, and X-Ray Detectors and Their Application to Microanalysis

1985 ◽  
Vol 43 ◽  
pp. 154-157
Author(s):  
A.J. Tousimis
Keyword(s):  
Ion Beam ◽  
Depth Resolution ◽  
Sample Surface ◽  
High Energy ◽  
X Rays ◽  
X Ray ◽  
Electrons And Ions ◽  
Spatial Depth ◽  
Minimum Surface Area ◽  
Physical Principles

An integral and of prime importance of any microtopography and microanalysis instrument system is its electron, x-ray and ion detector(s). The resolution and sensitivity of the electron microscope (TEM, SEM, STEM) and microanalyzers (SIMS and electron probe x-ray microanalyzers) are closely related to those of the sensing and recording devices incorporated with them.Table I lists characteristic sensitivities, minimum surface area and depth analyzed by various methods. Smaller ion, electron and x-ray beam diameters than those listed, are possible with currently available electromagnetic or electrostatic columns. Therefore, improvements in sensitivity and spatial/depth resolution of microanalysis will follow that of the detectors. In most of these methods, the sample surface is subjected to a stationary, line or raster scanning photon, electron or ion beam. The resultant radiation: photons (low energy) or high energy (x-rays), electrons and ions are detected and analyzed.

Comparison of high-angle take-off and low-angle take-off EDX detector geometry of the HF-2000 FE-TEM

1993 ◽  
Vol 51 ◽  
pp. 252-253
Author(s):  
Y. Sato ◽  
T. Hashimoto ◽  
M. Ichihashi ◽  
Y. Ueki ◽  
K. Hirose ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Field Emission ◽  
Solid Angle ◽  
Energy Dispersive ◽  
Objective Lens ◽  
X Rays ◽  
High Angle ◽  
X Ray ◽  
Detector Geometry

Analytical TEMs have two variations in x-ray detector geometry, high and low angle take off. The high take off angle is advantageous for accuracy of quantitative analysis, because the x rays are less absorbed when they go through the sample. The low take off angle geometry enables better sensitivity because of larger detector solid angle.Hitachi HF-2000 cold field emission TEM has two versions; high angle take off and low angle take off. The former allows an energy dispersive x-ray detector above the objective lens. The latter allows the detector beside the objective lens. The x-ray take off angle is 68° for the high take off angle with the specimen held at right angles to the beam, and 22° for the low angle take off. The solid angle is 0.037 sr for the high angle take off, and 0.12 sr for the low angle take off, using a 30 mm2 detector.

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