Grazing Incidence Angle Research Articles

Hot spot localization in the field of view of the Kirkpatrick–Baez microscope

The Kirkpatrick–Baez (KB) microscope is an effective instrument for x-ray imaging of hot spot. However, the non-uniform distribution of response efficiency in the field of view is a drawback of the KB microscope. A more accurate hot spot image requires the correction of the measured image by combining the hot spot position and the response efficiency distribution. Here, we describe a method to locate the position of the hot spot in the field of view during hot spot imaging with a KB microscope. The position of the hot spot in the field of view can be obtained by measuring the grazing incidence angle change during hot spot imaging. In the experiment of hot spot self-emission imaging with a four-channel KB microscope, the location of the hot spot with an accuracy of 15 μm was realized, and the intensity corrected hot spot image was obtained. This will solve the problem of the non-uniform distribution of the response efficiency of the KB microscope and enable quantitative measurement of hot spot radiation intensity.

Wetting behavior of stainless-steel surface with zinc oxide nanorod coatings: modulations in nanorod alignment through atomic layer deposition

This study investigated the hydrophobic-hydrophilic characteristics of zinc oxide (ZnO) nanorod coatings for potential biomedical applications. We examined the effects of different alignments of ZnO nanorods on the wetting and mechanical characteristics of the coatings. ZnO seed layers were prepared on stainless-steel plates using atomic layer deposition (ALD) at five different temperatures ranging from 50 to 250 °C. The ZnO nanorod coatings were then deposited on these seed layers through chemical bath deposition. The polycrystalline structure of the seed layers and the morphology of the nanorods were analyzed using grazing incidence angle x-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Mechanical and wetting properties of the nanorod coatings were examined using nanoindentation and water-droplet tests. The seed layers produced at 50 and 250 °C showed stronger (0 0 2) peaks than the other layers. ZnO nanorods on these seed layers exhibited greater vertical orientation and lower water contact angles indicating a more hydrophilic surface. Additionally, vertically oriented nanorod coatings demonstrated greater elastic modulus and hardness than those of oblique nanorods. Our findings indicate that ALD technology can be used to control the spatial arrangement of ZnO nanorods and optimize the hydrophobic-hydrophilic and mechanical properties of coating surfaces.

Method for stabilizing the detection efficiency of grazing angle incidence boron-lined neutron detectors

Boron-lined gaseous neutron detectors intrinsically suffer from the “self-absorption” effect and hence their neutron detection efficiencies might be nonconstant, when the threshold of them undergoes unexpected variation. To address this problem, we propose a maximum likelihood estimation-based threshold determining method, via which the pulse height spectra acquired under different high voltages could be rescaled to the same abscissa axis of deposited energies. Monte Carlo simulations were conducted to study the relationship between the precision of the threshold determination and the counting statistics, as well as the energy deposition spectrum, indicating that the grazing angle incidence neutron detector can achieve a fairly small relative standard variation for a spectrum with a modest total neutron counts. A prototype grazing angle incidence neutron detector has been constructed and tested under high voltages ranging from 500 V to 950 V. The experimental results show that, with the maximum likelihood estimation-based method, the threshold's relative standard deviations are less than 10% even with a total neutron counts as low as 100. As a result, the maximum relative variance of the counting plateau curve is 4.8% in the region of [500 V, 900 V] when the detector operates at a grazing angle of 1.8°. The results presented in this study indicate that combining the grazing angle incidence and the maximum likelihood estimation-based threshold determining method would be a promising way to achieve stable neutron detection efficiency for neutron detectors with the boron layer as the neutron convertor.

Stability of titanium deuteride films irradiated with pulsed ion beams

Titanium deuteride films are widely used as target materials for neutron generators. Intense pulsed ion beams irradiated titanium deuteride films, and their structure stabilities were investigated by combination with scanning electron microscopy, transmission electron microscopy, grazing incidence angle X-ray diffraction, slow positron beam, scratch test and finite element analysis. The beam energy density was 0.3 J/cm2. Five different irradiation fluences of 3 × 1014, 1 × 1015, 3 × 1015, 1 × 1016, 3 × 1016 cm−2 were performed at room temperature. The adhesion strength between the film and Mo substrate decreased with increasing fluence. Moreover, surface melting and grain growth occurred after the beam irradiation with fluences over 3 × 1015 cm−2. The morphology of scratch tracks shows that the titanium deuteride film suffers a transition from ductile fracture to brittle fracture with increasing fluence. The reason for the decreasing adhesion strength was discussed via the introduction of thermal stress and lattice structure recovery. The research result is critical for evaluating the lifetime of titanium deuteride films based on failures in structures and a decrease in concentration of the inner deuterium.

SpuBase: Solar Wind Ion Sputter Database for Modeling Purposes

We supply the modelers with a database, SpuBase (doi:10.5281/zenodo.10783295), that is based on the latest approach for obtaining solar wind ion sputter yields in agreement with experimental sputter data outlined in Jäggi et al. We include an overview of sputter results for typical Lunar and Hermean surfaces. To obtain total sputter yields for any given surface, we perform a mass balance of individual mineral sputter yields. For a set of impact angles, the angular and energy distribution data are scaled according to the sputter yield, summed up and fitted to obtain one probability distribution for each chemical element involved. Comparison of the results from different geochemical terranes on the Moon and Mercury has shown that variations in the abundance of silicates result in comparable energy and angular distribution data owing to the underlying model assumptions. The inclusion of sulfides relevant for Mercury, however, significantly affects the energy and angular distributions of sputtered particles. The application of the damage-driven sulfur diffusion rate in FeS in all sulfur-bearing minerals results in 35 times lower sulfur yields on average and a less prominent forward sputtering of sulfur at grazing incidence angles.

Design and fabrication of Cu conical (Spiral+Helical) sculptured thin films and their application in SERS

Cu conical (spiral + helical (spiral (3 turns) + helical (2, 12 and 17 turns)) nanostructures were grown on stainless steel mesh (SSM) and glass microscope slide by glancing angle deposition (GLAD). The SSM substrates were used in surface enhanced Raman spectroscopy (SERS) for detection of 4,4′-Bipyridine (4,4′-Bipy) molecules. This design fulfilled the main electromagnetic mechanisms of enhancement of Raman signals, which are near field coupling and the lightning rod effect. The size of the sculptured nanostructures produced on the SSM substrates matched the wavelength of the laser beam of the Raman spectrometer and satisfied the requirements for the enhancement of the surface Raman spectroscopy of the 4,4′-Bipy molecules. A comparison is made on the morphology of the produced nanostructures on SSM, microscope slide and previously published works on other surfaces with the view to different surfaces with different surface roughness. Field emission scanning electron microscope (FESEM) analysis of the samples clearly revealed the morphology of the designed and fabricated nanostructure as conical (spiral + helical) features on both SSM and glass substrates. Crystal structures and optical spectra of the produced samples obtained using grazing angle incident x-ray diffraction (GIXRD) and Vis-NIR spectroscopy. The SERS results showed that although according to the GIXRD data the coated Cu films were oxidized, good enhancement is obtained. Hence, this can be considered as a favor to the applied fields of these samples. Vis-NIR results showed that as the number of turns of the helical part of the structure increased, the absorption of the spectra increased consistent with the discrete dipole approximation (DDA) results reported in the literature. Surface-enhanced Raman spectroscopy results of this work when compared with the available published data showed higher/comparable enhancement irrespective of the type of material used (e.g., Ag, Au and Mn), 4,4′-Bipy concentration, Bipy substrate shape, the method of fabrication and the excitation wavelength of the Raman spectrometer.

On matching a microwave radiation with the plasma of an electron cyclotron resonance discharge

This article proposes a scheme for matching microwave radiation with a magnetized plasma of an electron cyclotron resonance (ECR) discharge in an open magnetic trap, using the effect of depolarization—the transformation of the ordinary wave into the extraordinary one upon reflection from the metal walls of a plasma chamber. An analysis of the efficiency of such a transformation is carried out, and it is shown that for grazing (less than 15° with metal surface) angles of incidence; it is possible to achieve an efficiency exceeding 90%.

Sorption-Induced Fiber Optic Plasmonic Gas Sensing via Small Grazing Angle of Incidence.

Sensing technologies based on plasmonic nanomaterials are of interest for various chemical, biological, environmental, and medical applications. In this work, w e report an incorporation strategy of colloidal plasmonic nanoparticles (pNPs) in microporous polymer for realizing distinct sorption-induced plasmonic sensing. This approach is demonstrated by introducing tin-doped indium oxide pNPs into a polymer with intrinsic microporosity (PIM-1). The composite film (pNPs-polymer) provides distinct and tunable optical features on the fiber optic (FO) platform that can be used as a signal transducer for gas sensing (e.g., CO2 ) under atmospheric conditions. The resulting pNPs-polymer composite demonstrates high sensitivity response on FO in the evanescent field configuration, provided by the dramatic response of modes above the total-internal-reflection angle. Furthermore, by varying the pNPs content in the polymer matrix, the optical behavior of the pNPs-polymer composite can be tuned to affect the operational wavelength by over several hundred nanometers and the sensitivity of the sensor in the near-infrared range. W e also show that the pNPs-polymer composite film exhibits remarkable stability, over a period of more than ten months, by mitigating the physical aging issue of the polymer. This article is protected by copyright. All rights reserved.

Infiltration of CsPbI3:EuI2 Perovskites into TiO2 Spongy Layers Deposited by gig-lox Sputtering Processes

Perovskite solar cells have become a popular alternative to traditional silicon solar cells due to their potential to provide high-efficiency, low-cost, and lightweight solar energy harvesting solutions. However, the multilayer architecture of perovskite solar cells demands careful investigation of the interaction and interfacing between the various layers, as they play a crucial role in determining the overall performance of the cell. In this context, the present work aims at analyzing the coupling between a spongy transparent electron-transporting layer (ETL) and perovskite in a formulation CsPbI3:EuI2. The ETL used in this work is a transparent mesoporous TiO2 layer called “gig-lox” (grazing incidence angle geometry–local oxidation), which has been optimized to boost the interfacing with the perovskite for achieving a highly interconnected blend of materials. The gig-lox TiO2 ETL shows a high surface wettability with respect to the perovskite solution, especially after pre-annealing at 500 °C, and this enables the perovskite material to deeply infiltrate throughout it. The surface wettability of the gig-lox TiO2 has been estimated by contact angle measurements, while the deep infiltration of the perovskite material has been demonstrated through X-ray diffraction and transmission electron microscopy analyses. Thanks to the achieved deep infiltration, the photo-generated charge injection from the perovskite into the mesoporous oxide is enhanced with respect to the use of a planar compact oxide, as shown by the photoluminescence measurements. The mainstay of the approach resides in the ETL that is deposited by a solvent-free sputtering method and is up-scalable for high industrial throughput.

Bragg Curve Detection of Low-Energy Protons by Radiophotoluminescence Imaging in Lithium Fluoride Thin Films.

Lithium fluoride (LiF) crystals and thin films are utilized as radiation detectors for energy diagnostics of proton beams. This is achieved by analyzing the Bragg curves in LiF obtained by imaging the radiophotoluminescence of color centers created by protons. In LiF crystals, the Bragg peak depth increases superlinearly with the particle energy. A previous study has shown that, when 35 MeV protons impinge at grazing incidence onto LiF films deposited on Si(100) substrates, the Bragg peak in the films is located at the depth where it would be found in Si rather than in LiF due to multiple Coulomb scattering. In this paper, Monte Carlo simulations of proton irradiations in the 1-8 MeV energy range are performed and compared to experimental Bragg curves in optically transparent LiF films on Si(100) substrates. Our study focuses on this energy range because, as energy increases, the Bragg peak gradually shifts from the depth in LiF to that in Si. The impact of grazing incidence angle, LiF packing density, and film thickness on shaping the Bragg curve in the film is examined. At energies higher than 8 MeV, all these quantities must be considered, although the effect of packing density plays a minor role.

SHIFTS OF THE KIESSIG OSCILLATIONS AND FARADAY ROTATION FOR X-RAY REFLECTIVITY FROM A MAGNETIZED FILM

Appearance of the refraction effects and Faraday rotation of the plane of polarization of linearly polarized X rays has been analyzed for transmission and reflection at grazing incidence angles for a resonant film with allowance for the X-ray magnetic or Mössbauer scattering. It is shown that, when the magnetization is oriented along the radiation beam direction, magnetic additives to the susceptibility do not affect the phase shifts between the waves reflected from the surface and the substrate; however, they induce “orthogonal polarization” in the reflected beam, which corresponds to rotation of the plane of polarization. Rotation of the plane of polarization is maximum for the critical angle of total external reflection; it is characterized by an oscillating dependence on the grazing angle, which can be used in future to vary the polarization state of X-ray beams.

Stress Effects of Interconnecting Metals on Back-End-of-Line Compatible Hf0.5Zr0.5O2 Ferroelectric Capacitors

The back-end-of-line (BEOL) process compatibility is one of the advantages of Hf0.5Zr0.5O2 (HZO)-based ferroelectric (FE) among other kinds of HfO2-doped FEs. However, the impact of stress effect induced by the interconnects during device stacking cannot be ignored. Previous studies about the stress effect have mainly focused on the metal in direct contact with the FE layer, but have neglected the potential effects of other layers covering the electrodes. In this work, the stress effects of interconnecting metals including Cu and W, which are the most mainstream interconnects in modern integrated circuit (IC) technology, are systematically demonstrated. The capping layers can exert stress on the top electrode (TE), and this stress transfers to the HZO layer during annealing, which affects the crystalline state of HZO films and enhances or suppresses the ferroelectricity. This is verified by the devices’ electrical performance, the residual stresses measurements and grazing-angle incidence X-ray diffraction results. The results can guide the selection of the proper annealing timing for large-scale FE memory integration when utilizing the BEOL process with different interconnects.

The soft X-ray and XUV split-and-delay unit at beamlines FL23/24 at FLASH2.

A split-and-delay unit for the extreme ultraviolet and soft X-ray spectral regions has been built which enables time-resolved experiments at beamlines FL23 and FL24 at the Free-electron LASer in Hamburg (FLASH). Geometric wavefront splitting at a sharp edge of a beam splitting mirror is applied to split the incoming soft X-ray pulse into two beams. Ni and Pt coatings at grazing incidence angles have been chosen in order to cover the whole spectral range of FLASH2 and beyond, up to hν = 1800 eV. In the variable beam path with a grazing incidence angle of ϑd = 1.8°, the total transmission (T) ranges are of the order of 0.48 < T < 0.84 for hν < 100 eV and T > 0.50 for 100 eV < hν < 650 eV with the Ni coating, and T > 0.06 for hν < 1800 eV for the Pt coating. For a fixed beam path with a grazing incidence angle of ϑf = 1.3°, a transmission of T > 0.61 with the Ni coating and T > 0.23 with a Pt coating is achieved. Soft X-ray pump/soft X-ray probe experiments are possible within a delay range of -5 ps < Δt < +18 ps with a nominal time resolution of tr = 66 as and a measured timing jitter of tj = 121 ± 2 as. First experiments with the split-and-delay unit determined the averaged coherence time of FLASH2 to be τc = 1.75 fs at λ = 8 nm, measured at a purposely reduced coherence of the free-electron laser.

Damage resistance of B4C reflective mirror irradiated by X-ray free-electron laser

In this paper, a simple theoretical model combining Monte Carlo simulation with the enthalpy method is provided to simulate the damage resistance of B4C/Si-sub mirror under X-ray free-electron laser irradiation. Two different damage mechanisms are found, dependent on the photon energy. The optimum B4C film thickness is determined by studying the dependence of the damage resistance on the film thickness. Based on the optimized film thickness, the damage thresholds are simulated at photon energy of 0.4–25 keV and a grazing incidence angle of 2 mrad. It is recommended that the energy range around the Si K-edge should be avoided for safety reasons.

A Grazing Incidence Variable Line-spacing Spherical Grating Monochromator for SwissFEL

In this paper, we present a soft x-ray variable line-spacing spherical grating monochromator, which is shared between the three ATHOS beamlines at SwissFEL. The instrument uses grazing incidence angles of less than 3° to withstand the peak-fluence of femtosecond FEL pulses with energies up to 8 mJ. The upward facing monochromator grating facilitates endstations with different beam heights. We explain the integration of the monochromator into the beamlines; discuss its mechanical design, its control system and its optical components. We conclude with showing an initial calibration spectrum and detail the currently achieved performance.

Brewster metasurfaces for ultrabroadband reflectionless absorption at grazing incidence

Previous reflectionless metasurfaces based on balanced electric and magnetic responses in engineered resonant meta-atoms become ineffective at oblique incident angles and usually have strong reflection at grazing incidence, where the impedance becomes near-zero or divergent. Here, by introducing the concept of anomalous generalized Brewster effect to metasurfaces, we demonstrate an exceptional resonance-free Brewster metasurface that exhibits ultrabroadband zero reflection at grazing incidence. The anomalous generalized Brewster effect is obtained via combining the mechanisms of the generalized Brewster effect and the anomalous Brewster effect, which are both resonance-free and thus enable ultrabroadband functionalities. As a practical application, Brewster metasurfaces exhibiting ultrabroadband reflectionless perfect absorption at grazing incident angles are constructed and demonstrated by full-wave simulations and microwave experiments. Our work could enable reflectionless wave manipulation at grazing incidence with an ultrawide working bandwidth.

Growth characteristics and properties of RuAlO hybrid films fabricated by atomic layer deposition

In this work, RuAlO hybridfilmswere synthesized by alternating ALD sequences of Al2O3and Ru for electrical conductivity regulation.O2exposure has significant effectson the nucleation and etching processes of Ru, therefore the O2exposure was first optimized for efficient growth of Ru. A set of RuAlOhybrid films with different Ru subcycle ratioswere fabricated.In-situ quartz crystal microbalance (QCM) measurementrevealed acertain nucleation delaywhenRu was deposited on the surface ofAl2O3, whileno nucleation delay was observed when Al2O3was deposited on Ru. High resolution transmission electron microscopy(HRTEM) characterization confirmed formation ofRu grains embedded in amorphous Al2O3matrix. Elemental mapping results demonstrated that RuandAlelementsareuniformly distributedon the cross section ofthe film.In the grazing incidence angle X-ray diffraction (GIAXRD) patterns ofRuAlOhybrid films,characteristic diffraction peaks of Ru appear with aRusubcycle ratio ≥ 70 %. By properly tuning the Ru to Al2O3ALD subcycle ratio, electrical resistivity of theRuAlOhybrid film could beadjusted over a wide range of 10-3 ∼ 1011Ω·cm.

Ultra-low Young's modulus Zr-Nb thin films on Mg substrate for enhanced corrosion resistance

Controlling the degradation rate of magnesium (Mg) via applying the (Zr-Nb) thin films was investigated in this study. The Zr-2.5Nb coatings were deposited on the Mg with thicknesses of 250, 450, 650, and 900 nm (hereafter named [email protected], [email protected], [email protected], and [email protected]), respectively. Grazing incidence angle X-ray diffraction of (Zr-Nb) coatings revealed the alpha phase of zirconium and dominant (002) texture, with the film thickness increasing from 450 nm to 900 nm. Potentiodynamic polarization, electrochemical impedance spectroscopy, and corrosion morphology observations in Dulbecco's Modified Eagle's cell culture medium (DMEM) solution revealed the (Zr-2.5Nb)-coated mg with the thickness of [email protected] sample provides the highest corrosion resistance compared to other studied thicknesses. [email protected] sample increases the corrosion potential from −1.49 V to −1.38 V and decreases the current corrosion density and corrosion rate from 149.32 (μA.cm−2) to 39.01 (μA.cm−2) and from 3.49 (mm.y−1) to 0.912 (mm.y−1), respectively. Further studies on the surface of the [email protected] sample in terms of nano-mechanical properties demonstrated that Young's modulus and hardness are 47.95± 4.43 GPa and 2.25± 0.41 GPa, respectively, which increases the hardness to reduced Young's modulus ratio, which is known as one of the important parameters in developing of temporary orthopedic implants, of the Mg from 0.03 to 0.06. Furthermore, nano-tribological measurements and atomic force microscopy observations confirmed that detachment or breakage are not observed. Zr-2.5Nb coating, owing to the influence only on the first stage of the degradation reduced the degradation rate of Mg surafce, and therefore, can be considered as a practical strategy for further development of Mg in orthopedic applications.

Experimental Measurement of Forward Scattering from Very Rough Sand Ripples in a Water Tank

High order Bragg scattering from sand ripples is investigated by a tank experiment, where the artificially produced sand ripples have a spatial period of 0.2 m and ripple height of 5 cm. Bragg scattering has been measured at three frequencies 22 kHz, 24.57 kHz, and 27 kHz and three incident grazing angles 20∘, 30∘, 40∘ by a method based on the conventional beamforming using two horizontal receiving arrays. It is illustrated that high order Bragg scatterings can be observed, and the corresponding scattered grazing angles agree with the theoretical prediction. Owing to the ripple height being on the order of wavelength, it is found that the distribution of forward scattering amplitude is different from the distribution for sand ripples of small height, i.e., the diffuseness of scattering amplitude is increased with the ripple height.

Few‐Layered ReS2@CNTs as a High‐Performance Cathode for Aluminum‐Ion Batteries

AbstractWith a high theoretical specific capacity of 2978 mAh g−1, rechargeable aluminum‐ion batteries (AIBs) are considered as promising next‐generation energy storage devices with higher electrochemical performance. Nevertheless, the search for stable cathode materials with outstanding capacity and rate performance remains elusive. In current work, few‐layered ReS2 is in situ grown on carbon nanotubes (CNTs) to form the ReS2@CNTs composite. As ReS2 features a large interlayer spacing of ≈0.65 nm, the extremely weak interlayer coupling can effectively reduce the electrostatic repulsion between Al3+ ions and the cathode host, adequately accommodating large amounts of Al3+ ions without significant volume expansion. When it serves as the cathode in the AIB, ReS2@CNTs delivers a high discharge specific capacity of 396.3 mA h g−1 and Coulombic efficiencies of ≈100% both after 250 cycles at a low rate (200 mA g−1) and 10 000 cycles under a higher rate (1 A g−1). Theoretical simulations and ex situ grazing incidence angle X‐ray diffraction results reveal that Al3+ cations can be favorably and reversibly intercalated/deintercalated into the ReS2@CNTs during the discharge/charge process. This work provides new insights into AIB chemistry and paves the way for the development of high‐performance AIBs.