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It is now known that Single-monochromator Brewer Spectrophotometer ozone and sulphur dioxide measurements suffer from non-linearity at large ozone slant column amounts due to the presence of instrumental stray light caused by scattering within the optics of the instrument. Because of the large gradient in the ozone absorption spectrum in the near-ultraviolet, the atmospheric spectra measured by the instrument possess a very large gradient in intensity in the 300 to 325nm wavelength region. This results in a significant sensitivity to stray light when there is more than 1000 Dobson Units (DU) of ozone in the light path. As the light path (airmass) through ozone increases, the stray light effect on the measurements also increases. The measurements can be on the order of 10% low for an ozone column of 600DU and an airmass factor of 3 (1800DU slant column amount) causing an underestimation of the ozone column. Primary calibrations for the Brewer instrument are carried out at Mauna Loa Observatory in Hawaii. They are done using the Langley plot method to extrapolate a set of measurements made under a constant ozone amount to an extraterrestrial calibration constant. Since the effects of a small non-linearity at lower ozone paths may still be important, a better calibration procedure should account for the non-linearity of the instrument response. Studies involving the scanning of a laser source have been used to characterize the stray light response of the Brewer, but until recently these data have not been used to elucidate the relationship between the stray light response and the ozone measurement non-linearity. This paper presents a simple and practical method of correcting for the effects of stray light that includes a mathematical model of the instrument response and a non-linear retrieval approach that calculates the best values for the model parameters. The model can then be used in reverse to provide more accurate ozone values up to a defined maximum ozone slant path. The parameterization used was validated using an instrument physical model simulation. [ABSTRACT FROM AUTHOR]

Purpose To compare the diagnostic value of monochromatic and material decomposition (MD) dual- energy computed tomography (DECT) imaging for the evaluation of ischemia. Methods Patients with suspected coronary artery disease underwent rest-stress DECT and SPECT perfusion imaging. DECT images were reconstructed between 40 and 140 keV and through MD of iodine/muscle. Results MD and monochromatic imaging had a sensitivity, specificity, negative predictive, positive predictive value, and accuracy of 89%, 40%, 67%, 73% and 71%; and 91%, 67%, 67%, 91% and 86%, respectively ( p = 0.05). Conclusion DECT using monochromatic energy displayed a non-significantly higher diagnostic accuracy for myocardial ischemia as compared with DECT MD. [ABSTRACT FROM AUTHOR]

From 25 May to 5 June 2015, the 10th regional intercomparison campaign of the Regional Brewer Calibration Center - Europe (RBCC-E) was held at El Arenosillo atmospheric sounding station of the Instituto Nacional de Técnica Aeroespacial (INTA). This campaign was jointly conducted by COST Action ES1207 EUBREWNET and the Area of Instrumentation and Atmospheric Research of INTA. A total of 21 Brewers, 11 single- and 10 double-monochromator instruments from 11 countries participated and were calibrated for total column ozone (TOC) and solar UV irradiance. In this 2015 campaign we have introduced a formal approach to the characterisation of the internal instrumental stray light, the filter non-linearity and the algorithm for correcting for its effects on the TOC calculations. This work shows a general overview of the ozone comparison and the evaluation of the correction of the spectral stray light effect for the single-monochromator Brewer spectrophotometer, derived from the comparison with a reference double-monochromator Brewer instrument. At the beginning of the campaign, 16 out of the 21 participating Brewer instruments agreed within better than ±1%, and 10 instruments agreed within better than ±0.5% considering data with ozone slant column between 100 and 900DU, which does not require instrumental stray light correction. [ABSTRACT FROM AUTHOR]

This article reports the development and characterization of a laboratory‐based high‐resolution X‐ray powder diffractometer equipped with a 5.5 T magnet and closed‐cycle helium cryostat that is primarily designed for the investigation of magneto‐structural phase transitions. Unique features of the diffractometer include the position‐sensitive detector, allowing the collection of an entire diffraction pattern at once, and the high energy resolution with Mo Kα1 radiation. The ability to utilize a lower energy resolution but higher photon flux by switching to an X‐ray mirror monochromator makes it a versatile setup for a variety of compounds. In this contribution, details of the design and performance of the instrument are presented along with its specifications. [ABSTRACT FROM AUTHOR]

The optical design for the high-energy x-ray diffraction and scattering beamline of the Brockhouse sector at the Canadian Light Source is described. The design is based on a single side-bounce silicon focusing monochromator that steers the central part of a high-field permanent magnet wiggler beam into the experimental station. Two different configurations are proposed: a higher energy resolution with vertical focusing and a lower energy resolution with horizontal and vertical focusing. The monochromator will have the possibility of mounting three crystals: one crystal optimized for 35 keV that focuses in the horizontal and vertical directions using reflection (1,1,1) and two other crystals both covering the energies above 40 keV: one with only vertical focusing and another one with horizontal and vertical focusing. The geometry of the last two monochromator crystals was optimized to use reflections (4,2,2) and (5,3,3) to cover the broad energy range from 40 to 95 keV. [ABSTRACT FROM AUTHOR]

Aims: Delafloxacin is a fluoroquinolone antibiotic recently approved by the FDA for treatment of acute bacterial skin and skin structure infections (ABSSSI). Delafloxacin was assessed for phototoxicity potential compared with a known phototoxic fluoroquinolone. Methods: A Phase 1, investigator-blind, placebo/active-controlled, randomized, parallel-group study was conducted in 52 healthy male and female volunteers who received 200 or 400 mg of oral delafloxacin, 400 mg oral lomefloxacin or placebo once daily for 6 days. This study evaluated the photosensitizing potential and possible wavelength dependency of delafloxacin by comparing the response of the skin to ultraviolet A (UVA), ultraviolet B (UVB) and visible radiation prior to and during administration of delafloxacin, lomefloxacin as a positive control, or placebo. Adverse events were monitored throughout the study. Results: Forty-seven subjects completed six days of dosing, and no evidence of phototoxicity was seen with delafloxacin. Delafloxacin at 200 and 400 mg day−1 and placebo did not demonstrate differences in percent change from baseline in minimal erythema dose at all tested wavelengths (295–430 nm) by monochromator and solar simulator. Lomefloxacin, the positive control, had statistically significant differences (p ＜ 0.05) at UVA wavelengths of 335 and 365 ± 30 nm 24 hours after radiation exposure (maximum response). The phototoxic index results were significantly higher for lomefloxacin at 335 nm and 365 nm compared to placebo and delafloxacin. Conclusions: 200 and 400 mg of delafloxacin administered for 6 days were well tolerated in healthy adult volunteers. Delafloxacin and placebo failed to demonstrate a phototoxic effect but lomefloxacin, the positive control, demonstrated moderate phototoxicity. [ABSTRACT FROM AUTHOR]

We present the results of investigations of extreme ultraviolet (EUV) light emission in the range from 5 to 10 nm. The light source was a pulsed “double-stream” Xe:He gas jet target irradiated by a laser beam with a power density of ∼1011 W/cm2. The radiation spectra were measured with a Czerny-Turner monochromator with a plane diffraction grating. The conversion efficiency of the laser energy into EUV radiation caused by Xe+14…+16 ion emission in the range of 6–8 nm was measured using a calibrated power meter. The conversion efficiency of the laser radiation into EUV in the vicinity of 6.7 nm was (2.17 ± 0.13)% in a 1 nm spectral band. In the spectral band of the real optical system (0.7% for La/B multilayer mirrors) emitted into the half-space, it was (0.1 ± 0.006)%. The results of this study provide an impetus for further research on laser plasma sources for maskless EUV lithography at a wavelength of 6.7 nm. [ABSTRACT FROM AUTHOR]

The molecular structure of the selenides of [R 2 P(Se)] 2 Se type has been systematically studied on example of bis(dicyclohexylselenophosphinyl)selenide, [Cy 2 P(Se)] 2 Se. This selenide has been synthesized in 65% yield by oxidation of Cy 2 PH with elemental selenium in 1:2 M ratio. Its structure has been investigated by X-ray diffractometry (XRD), NMR, FT-IR and MALDI-TOF/MS techniques. In the solid, the Se 1 P Se 2 P Se 3 chain of (Cy 2 P = Se) 2 Se molecule adopts a syn-anti conformation with the Se 1 P Se 2 P and P Se 2 P Se 3 torsion angles of −179.64 (3)° and 4.69 (4)°. The vibrational band assignments, performing at B3LYP/6-311++G (d,p) theory level, are in a good agreement with the experimental FT-IR frequencies. The synthetic utility of the prepared selenide has been exemplified by its reaction with CuCl 2 resulted in the formation of [Cu 4 (Se 2 PCy 2 ) 4 ] cluster in 53% yield. The structure of latter is formed by a Cu 4 tetrahedron, wherein each triangular face is bridged by a [Se 2 PCy 2 ] ligand in a trimetallic triconnective ( μ 2 , μ 1 ) pattern. [ABSTRACT FROM AUTHOR]

Abstract: Zur Untersuchung von Mahlreaktionen in Echtzeit wurden drei analytische Methoden gekoppelt: Synchrotron‐Röntgenbeugung mit Raman‐Spektroskopie und Thermographie. Diese Methodenkombination ermöglicht es, die strukturelle Entwicklung mit Temperaturinformationen zu korrelieren. Die Temperaturinformation ist entscheidend für das Verständnis von Thermodynamik und Reaktionskinetik. Exemplarisch wurde der Reaktionsmechanismus von drei mechanochemischen Modell‐Synthesen, einer Cokristallbildung, einer C‐C‐Bindungsknüpfung (Knoevenagel‐Kondensation) und der Bildung einer metallorganischen Verbindung, eines Mangan‐Phosphonats, aufgeklärt. Allgemeine Trends bezüglich der Temperaturentwicklung beim Mahlen konnten identifiziert werden. Die Reaktions‐ und Kristallisationswärme tragen zur gesamten Temperaturerhöhung bei. Eine Erniedrigung der Temperatur tritt bei Freisetzung von z. B. Wasser als Nebenprodukt auf. Die drei unabhängigen Methoden ergänzen sich gegenseitig, wodurch der Informationsgewinn maximiert und der Nachweis fester sowie flüssiger Intermediate ermöglicht wird. Schließlich konnte der Einfluss der mechanischen Einwirkung von den durch die Reaktion hervorgerufenen Temperatureinflüssen unterschieden werden. [ABSTRACT FROM AUTHOR]

We report an overview of soft X-ray scientific instruments and X-ray optics at the free electron laser (FEL) of the Pohang Accelerator Laboratory, with selected first-commissioning results. The FEL exhibited a pulse energy of 200 μJ/pulse, a pulse width of <50 fs full width at half maximum, and an energy bandwidth of 0.44% at a photon energy of 850 eV. Monochromator resolving power of 10 500 was achieved. The estimated total time resolution between optical laser and X-ray pulses was <270 fs. A resonant inelastic X-ray scattering spectrometer was set up; its commissioning results are also reported. [ABSTRACT FROM AUTHOR]

The paper deals with the quality measurement process using the KEYENCE® industrial monochromatic camera and its calibration to determine the dimensions of the component under quality control process. The threshold value determines the shape of the component and the histogram method determines the number of pixels of the selected analyzed area. After calibrating the camera with a scale and changing the camera's distance to the object, a general equation was obtained from the measured points. Using this equation, it is possible to determine the size of the measured object from pixels. The average relative error of the object's dimensions was: length - 1.94 % and the width of 100 components was: 1.31 %. In quality control, monochrome cameras can be used to measure product dimensions, along with image processing principles and with other measure methods. [ABSTRACT FROM AUTHOR]

Electron beam monochromators (MCs) and energy analyzers (EAs), which are equivalent optical units with energy filtering capabilities, are of importance in electron microscopy and surface analysis instruments. The authors report the evaluation results for electron optics with an offset cylindrical lens (CL) and an additional transfer lens (TL) for application to an MC or EA. The offset CL deflects beams and generates energy dispersions, and the TL enhances their performance through collimating and retarding the beams. Following the previous theoretical studies, the authors have designed and manufactured the optics with a high mechanical accuracy at the micrometer level and integrated it with electronics with low noise and high stability. The authors adopt two methods for evaluating the energy-resolving performance. First, the authors treat the optics as an EA and evaluate the resolution through comparing the measured total energy distributions of Schottky emitters with the results from the theory. The energy resolution dE is estimated to be 88 meV at a beam energy E0 of 3.1 keV, and the index of performance dE/E0 reaches 2.7 × 10−5. Second, the authors treat the optics as an MC and evaluate directly the energy resolution or the energy spread of the monochromatic beams with an additional EA on the downstream side. The energy resolution dE is 73 meV. Both methods show similar energy resolutions, which enhance the credibility of the evaluation results. Charged particle simulation confirms the results and reveals that the resolution is limited by the width of the energy selection slit. As a total measurement system, the accuracy and stability are better than 3 meV. The MC with the optics exhibits high potential and a simple structure and is suitable for practical use. Advantages of the EA are band-pass filtering type, linear optics, compact size, and easy integration into analytical systems. The MC or EA using the optics will open new possibilities in the research fields of materials science, biology, and electronic devices, where advanced EMs or surface analytical instruments play essential roles. [ABSTRACT FROM AUTHOR]

The development of high-performance neutron monochromators is a long-standing and still actual topic in neutron instrumentation. Due to its high scattering cross section, iron is a particularly interesting material since it offers the possibility to obtain high reflectivities at small wavelength and good resolution. Phase transitions between bcc - and fcc -phases hindered the growth of large and high-quality single crystals in the past and only recently bcc -crystals became commercially available. We have characterized the reflecting properties of as-grown and deformed crystals using γ -rays and thermal neutrons. Absolute reflectivities well above 30% for neutron wavelengths near 1 Å could be obtained that are superior to that of all other existing monochromator materials. Hence, the progress in crystal growth along with the knowledge of directed plastic deformation makes the development of bcc -Fe neutron monochromators feasible. Their application in crystal-monochromator instruments is suitable to increase the useful neutron flux at large energies considerably. [ABSTRACT FROM AUTHOR]

The kinetics of reduction of a 10 wt %Fe2O3‐MgAl2O4 spinel were investigated using XRD and time resolved Fe‐K QXANES. The Rietveld refinement of the XRD pattern showed the replacement of Al with Fe in the spinel structure and the formation of MgFeAlOx. The XANES pre‐edge feature was employed to study the reduction kinetics during H2‐TPR (Temperature Programmed Reduction) up to 730°C. About 55% of the Fe3+ in MgFeAlOx was reduced to Fe2+. A shrinking core model, which takes into account both solid‐state diffusion via an oxygen diffusion coefficient, and gas‐solid reaction through a reaction rate coefficient, was applied. The activation energy for chemical reaction showed a linear dependence on the conversion, increasing from 104 to 126 kJ/mol over the course of material reduction. The good accordance between the shrinking core model description and the experimental data indicates that XANES pre‐edge features can be used to correlate changes in material structure and reaction kinetics. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1339–1349, 2018 [ABSTRACT FROM AUTHOR]

In this article, we present the first X-ray calibration performed over the 0.1–1.5 keV spectral range by means of a soft X-ray Manson source and the monochromator SYMPAX. This monochromator, based on a classical Rowland geometry, presents the novelty to be able to board simultaneously two detectors and move them under vacuum in front of the exit slit of the monochromatizing stage. This provides the great advantage to perform radiometric measurements of the monochromatic X-ray photon flux with one reference detector while calibrating another X-ray detector. To achieve this, at least one secondary standard must be operated with SYMPAX. This paper presents thereby an efficiency transfer experiment between a secondary standard silicon drift detector (SDD), previously calibrated on BESSY II synchrotron Facility, and another one (“unknown” SDD), devoted to be used permanently with SYMPAX. The associated calibration process is described as well as corresponding results. Comparison with calibrated measurements performed at the Physikalisch-Technische Bundesanstalt (PTB) Radiometric Laboratory shows a very good agreement between the secondary standard and the unknown SDD. [ABSTRACT FROM AUTHOR]

Abstract: The role of borate anions in ionothermal syntheses of crystalline chalcogenidometalates was shown by the directed ionothermal synthesis of seven new selenidostannates in ionic liquids with either [BF4]− or [B(CN)4]− anions. Single crystal structures are presented of four compounds, (C4C1C1Im)5[Sn9Se20][BF4] (1, Im=imidazolium), (DMMPH)4[Sn2Se6] (2, DMMP=2,6‐dimethylmorpholine), (C2C1Im)2(DMMPH)2[Sn6Se14] (3), and K2[Sn3Se7] (4), and how the chosen ionic liquid anion, and the reaction temperature, influences the product spectrum is discussed: Notably, 1 contains an entire formula unit of the ionic liquid, (C4C1C1Im)[BF4], while 4 contains neither the cation nor the anion of the ionic liquid—both observations being very uncommon for ionothermal syntheses. Three further compounds were obtained that exhibit strong disorder in the crystal structures (I‐III), for which only their anionic substructures are discussed herein. Compound 4 and I‐III are based on the same layered selenidostannate substructure, 2D‐{[Sn3Se7]2−}, yet with different inter‐layer distances, which is clearly reflected in the crystal colors and quantitative optical absorption properties. [ABSTRACT FROM AUTHOR]

A new method for arsenic detection by optical emission spectrometry (OES) is presented. Arsine (AsH3) is generated from liquid solutions by means of hydride generation (HG) and introduced into a capillary dielectric barrier discharge (DBD) where it is atomized and excited. A great challenge in OES is the reduction of the recorded background signal, because it negatively affects the limit of detection (LOD). In conventional DBD/OES methods, the signal intensity of the line of interest, in this case arsenic, is integrated over a long time scale. However, due to the pulsed character of the plasma, the plasma on-time is only a small fraction of the integration time. Therefore, a high amount of noise is added to the actual signal in each discharge cycle. To circumvent this, in the present study the emitted light from the DBD is collected by a fast gated iCCD camera, which is mounted on a modified monochromator. The experimental arrangement enables the recording of the emission signal of arsenic in the form of a monochromatic 2D-resolved picture. The temporal resolution of the iCCD camera in the nanosecond range provides the information at which point in time and how long arsenic is excited in the discharge. With use of this knowledge, it is possible to integrate only the arsenic emission by temporally isolating the signal from the background. With the presented method, the LOD for arsenic could be determined to 93 pg mL-1 with a calibration curve linear over 4 orders of magnitude. As a consequence, the developed experimental approach has a potential for both mechanistic studies of arsine atomization and excitation in DBD plasmas as well as routine applications, in which arsenic determination at ultratrace levels is required. [ABSTRACT FROM AUTHOR]

Laser-power converters for the wavelength λ = 808 nm are fabricated by liquid-phase epitaxy (LPE) on the basis of n-Al0.07GaAs-p-Al0.07GaAs-p-Al0.25GaAs single-junction heterostructures. The converters are tested with uniform (pulse simulator) and partly nonuniform (laser beam) illumination distribution over the photoreceiving surface. In the former case, a monochromatic efficiency of η = 53.1% is achieved for samples with an area of S = 4 cm² at a power of 1.2 W. At S = 10.2 mm² the efficiency is 58.3% at a laser power of 0.7 W. [ABSTRACT FROM AUTHOR]

White light excitation fluorescence (WLEF) is known to possess analytical advantage in terms of enhanced sensitivity and facile capture of the entire fluorescence spectral signature of multi component fluorescence systems. Using the zero order diffraction of the grating monochromator on the excitation side of a commercial spectrofluorimeter, it has been shown that WLEF spectral measurements can be conveniently carried out. Taking analyte multi-fluorophoric systems like (i) drugs and vitamins spiked in urine sample, (ii) adulteration of extra virgin olive oil with olive pomace oil and (iii) mixture of fabric dyes, it was observed that there is a significant enhancement of measurement sensitivity. The total fluorescence spectral response could be conveniently analysed using PLS2 regression. This work brings out the ease of the use of a conventional fluorimeter for WLEF measurements. [ABSTRACT FROM AUTHOR]

The correct determination of the X-ray peak areas in PIXE spectra by fitting with a computer program depends crucially on accurate parameterization of the detector peak response function. In the Guelph PIXE software package, GUPIXWin, one of the most used PIXE spectra analysis code, the response of a semiconductor detector to monochromatic X-ray radiation is described by a linear combination of several analytical functions: a Gaussian profile for the X-ray line itself, and additional tail contributions (exponential tails and step functions) on the low-energy side of the X-ray line to describe incomplete charge collection effects. The literature on the spectral response of silicon X-ray detectors for PIXE applications is rather scarce, in particular data for Silicon Drift Detectors (SDD) and for a large range of X-ray energies are missing. Using a set of analytical functions, the SDD response functions were satisfactorily reproduced for the X-ray energy range 1–15 keV. The behaviour of the parameters involved in the SDD tailing functions with X-ray energy is described by simple polynomial functions, which permit an easy implementation in PIXE spectra fitting codes. [ABSTRACT FROM AUTHOR]

The paper presents two procedures for the wavelength calibration, in the oxygen telluric absorption spectral bands (O2-A, λc = 687 nm and O2-B, λc = 760.6 nm), of field fixed-point spectrometers used for reflectance and Sun-induced fluorescence measurements. In the first case, Ne and Ar pen-type spectral lamps were employed, while the second approach is based on a double monochromator setup. The double monochromator system was characterized for the estimation of errors associated with different operating configurations. The proposed methods were applied to three Piccolo Doppio-type systems built around two QE Pros and one USB2 + H16355 Ocean Optics spectrometers. The wavelength calibration errors for all the calibrations performed on the three spectrometers are reported and potential methodological improvements discussed. The suggested calibration methods were validated, as the wavelength corrections obtained by both techniques for the QE Pro designed for fluorescence investigations were similar. However, it is recommended that a neon emission line source, as well as an argon or mercury-argon source be used to have a reference wavelength closer to the O2-B feature. The wavelength calibration can then be optimised as close to the O2-B and O2-A features as possible. The monochromator approach could also be used, but that instrument would need to be fully characterized prior to use, and although it may offer a more accurate calibration, as it could be tuned to emit light at the same wavelengths as the absorption features, it would be more time consuming as it is a scanning approach. [ABSTRACT FROM AUTHOR]

Abstract: The crystal grain size can be quantitatively calculated by Scherrer equation according to the diffraction peak broadening in the XRD curves. Actually, the results calculated by the Scherrer equation are the thickness that perpendicular to the crystal planes. However, in the actual XRD measurements, the broadening of the diffraction peaks is not only because of the Micro‐level changes of crystal such as grain size and lattice distortion, but also due to the instrumental broadening. Thus, the Scherrer equation is less reliable if the full width at half maximum caused by the physical broadening is smaller than that caused by the instrumental broadening. In this paper, it is concluded that the applicable range of the Scherrer equation will increases with the increasing diffraction angle. As an example of Scherrer equation's application, the calculation result for the maximum applicable scope of Si(100) films is 137 nm. [ABSTRACT FROM AUTHOR]

High-quality metrology with synchrotron radiation requires in particular a very high spectral purity of the incident beam. This is usually achieved by a set of transmission filters with suitable absorption edges to suppress high-order radiation of the monochromator. The at-wavelength metrology station at a BESSY-II bending-magnet collimated plane-grating monochromator (c-PGM) beamline has recently commissioned a high-order suppression system (HiOS) based on four reflections from mirrors which can be inserted into the beam path. Two pairs of mirrors are aligned parallel so as not to disturb the original beam path and are rotated clockwise and counter-clockwise. Three sets of coatings are available for the different energy ranges and the incidence angle is freely tunable to find the optimum figure of merit for maximum suppression at maximum transmission for each photon energy required. Measured performance results of the HiOS for the EUV and XUV range are compared with simulations, and applications are discussed. [ABSTRACT FROM AUTHOR]

This paper describes a method for rapid measurements of the specular X-ray reflectivity signal using an area detector and a monochromatic, well collimated X-ray beam (divergence below 0.01°), combined with a continuous data acquisition mode during the angular movements of the sample and detector. In addition to the total integrated (and background-corrected) reflectivity signal, this approach yields a three-dimensional mapping of the reciprocal space in the vicinity of its origin. Grazing-incidence small-angle scattering signals are recorded simultaneously. Measurements up to high momentum transfer values (close to 0.1 nm-1, also depending on the X-ray beam energy) can be performed in total time ranges as short as 10 s. The measurement time can be reduced by up to 100 times as compared with the classical method using monochromatic X-ray beams, a point detector and rocking scans (integrated reflectivity signal). [ABSTRACT FROM AUTHOR]

The extreme-ultraviolet double-stage imaging Raman spectrometer is a permanent experimental endstation at the plane-grating monochromator beamline branch PG1 at FLASH at DESY in Hamburg, Germany. This unique instrument covers the photon energy range from 20 to 200 eV with high energy resolution of about 2 to 20 meV (design values) featuring an efficient elastic line suppression as well as effective stray light rejection. Such a design enables studies of low-energy excitations like, for example, phonons in solids close to the vicinity of the elastic line. The Raman spectrometer effectively operates with four reflective off-axial parabolic mirrors and two plane-grating units. The optics quality and their precise alignment are crucial to guarantee best performance of the instrument. Here, results on a comprehensive investigation of the quality of the spectrometer diffraction gratings are presented. The gratings have been characterized by ex situ metrology at the BESSY-II Optics Laboratory, employing slope measuring deflectometry and interferometry as well as atomic force microscopy studies. The efficiency of these key optical elements has been measured at the at-wavelength metrology laboratory using the reflectometer at the BESSY-II Optics beamline. Also, the metrology results are discussed with respect to the expected resolving power of the instrument by including them in ray-tracing studies of the instrument. [ABSTRACT FROM AUTHOR]

We present a new method for more accurate in-flight calibration and correction of imaging spectrometer spectral response functions. Non-Gaussian tails of spectral response functions can be difficult to characterize in the laboratory, and calibration can shift during deployment. Consequently, in-flight techniques are useful for validating and updating laboratory measurements. Our approach exploits predictable changes in the shape of the oxygen A band across varying surface elevation, with diverse scene content providing numerical leverage to characterize spectral response tails 3–4 orders of magnitude below the peak. We present a correction to recover the nominal response function, and show case studies based on NASA's Next Generation Airborne Visible Infrared Imaging Spectrometer (AVIRIS-NG). Corrected radiances are better conditioned for downstream analysis by sensitive atmospheric codes. We evaluate accuracy using multiple independent standards: simulation studies; consistency with laboratory measurements; elimination of a surface pressure retrieval bias; better alignment of retrieved reflectance with ground reference data; and statistics of over 250 flightlines from a campaign across the Indian Subcontinent showing consistent improvements in atmospheric correction. [ABSTRACT FROM AUTHOR]

A new bending magnet based soft X-ray beamline for in situ analysis of energy materials at National Synchrotron Radiation Laboratory will be constructed and the optical design is presented. This beamline will mainly focus on nanomaterials and their applications in energy conversion, storage, and catalysis studies. A varied-line-spacing plane grating monochromator is employed to cover the photon energy region of 60–1000 eV by two plane varied line spacing gratings with central groove densities of 840 l/mm and 1400 l/mm respectively. The designed energy resolution power E ∕ Δ E is about 1300 ∼ 3000. The calculated flux is higher than 1 × 10 10 phs/s under 300 mA ring beam current for the whole covered photon energy. This beamline will provide a powerful and efficiency instrument in the future for users doing research on nanomaterials, energy materials and catalytic science. [ABSTRACT FROM AUTHOR]

The temporal response of double-grating monochromators is analyzed considering two effects on the ultrafast pulse given by the configuration. The first effect is the compensation of the pulse-front tilt, i.e., all the rays emitted by the source in different directions at the same wavelength have to travel the same optical path. The second effect is the group delay introduced by the two gratings, i.e., different wavelengths within the bandwidth transmitted by the slit travel different paths. The methodology to calculate the group delay introduced by the double-grating configuration is presented. Some practical design examples are provided to show the design rules and the achieved performances. [ABSTRACT FROM AUTHOR]

Measuring the external quantum efficiency (EQE) of a solar cell is a standard method to gain deeper insights into its opto-electrical properties. For the case of crystalline silicon solar cells, the EQE of a solar cell is often used to assess the quality of the emitter and the passivation scheme. However, the standard EQE measurement method employs a monochromator which means that several minutes are typically needed to complete a single measurement. In academic environments this can form a bottleneck in the research output, while in industrial environments with production speeds of at least 1800 wafers/hour EQE measurements cannot be readily used. In this work, we introduce a new patented characterization tool which we call the Fast Optical Measurement System (FOMS). When using the FOMS, it becomes possible to measure the EQE of amorphous and crystalline silicon solar cells about 3 orders of magnitude faster when compared to a conventional monochromatic measurement. This means that a measurement of the full visible/near-infrared (VIS/NIR) spectrum can be done in 1–10 s, without compromising on accuracy. Additionally, the FOMS can also be used to perform ultrafast reflectance/transmittance once further add-ons to the system are implemented. This opens a path to many optical applications, also outside the photovoltaics field, where fast and accurate broadband measurements are needed. [ABSTRACT FROM AUTHOR]

A light field camera has a powerful and unique capability of light-ray collection and post-processing of data. In this paper, we describe a micro-lens-array-based approach to acquire the light field, with the added utility provided by simultaneous placement of linear variable filters (LVF) directly in the camera’s pupil plane. The new imaging spectrometer is capable of collecting the spectral segment information in the entire spectral range through only one exposure. Owing to the potential application of spectral detection, interest in the spectrum detection ability of the system is on the rise. As pixel sizes are reduced, consideration of diffraction effects in the system becomes increasingly important. We discuss a light field spectral imaging system and its wave propagation analysis. Then, we simulate a system response using our diffraction model and discuss the spectral resolution calibration with the application of the system model. In addition, the spectral resolution of the light field spectral imaging system is tested using the monochromator method; the results are found to be in good agreement with the simulation results. [ABSTRACT FROM AUTHOR]

X-ray absorption spectroscopy (XAS) is an electronic absorption technique for which the initial state is a deeply buried core level. The photon energies corresponding to such transitions are governed primarily by the binding energies of the initial state. Because the binding energies of core electrons vary significantly among atomic species, this makes XAS an element-selective spectroscopy. Proper interpretation of XA spectra can provide detailed information on the local chemical and geometric environment of the target atom. The introduction of liquid microjet and flow cell technologies into XAS experiments has enabled the general study of liquid samples. Liquids studied to date include water, alcohols, and solutions with relevance to biology and energy technology. This Review summarizes the experimental techniques employed in XAS studies of liquid samples and computational methods used for interpretation of the resulting spectra and summarizes salient experiments and results obtained in the XAS investigations of liquids. [ABSTRACT FROM AUTHOR]

The results of studies on the development of laser sources in the UV and IR spectral ranges for the lidar systems operating on the basis of a method of laser fragmentation with subsequent laser-induced fluorescence (LF/LIF) are presented. It is shown that LF/LIF is an effective method for the remote detection of harmful and dangerous substances including nitrogen oxides in the atmosphere. The formation of a high-quality sounding UV radiation in excimer lasers and its transportation along the atmospheric path is studied. The causes are revealed that lead to the formation of noise arising in the atmosphere and limiting the sensitivity of the applied method. [ABSTRACT FROM AUTHOR]

The spectra and amplitude–time characteristics of the radiation of studied Sn and Fe-doped Ga2O3 crystals excited with a runaway electron beam and an excilamp with a wavelength of 222 nm were investigated. The main contribution to the luminescence of samples in the region of 280–900 nm under excitation with a beam was shown to be made by cathodoluminescence. In the Fe-doped crystal, a new cathodeand photoluminescence band was detected within a wavelength range of 650–850 nm. In the Sn-doped crystal, Vavilov–Cherenkov radiation was detected in the region of 280–300 nm using a monochromator and a photomultiplier. [ABSTRACT FROM AUTHOR]

A transmission grating can be formed from quasi-random pinhole arrays. We show here that this type of grating can reduce the higher diffraction orders effectively when an appropriate arrangement is used. A simple but accurate analytical model is provided to describe the physical mechanism that is responsible for suppression of the higher orders, and this model is verified through numerical simulations. In particular, the background intensity enhancement and the fluctuations in this intensity that are introduced by the quasi-random arrangement of pinholes are also assessed. The consistent one-to-one match produced between the diffraction directions and the wavelengths means that this type of grating has considerable potential for use in spectroscopic measurement and monochromator applications. [ABSTRACT FROM PUBLISHER]

Temperature characteristics of 980-nm-upconverted green 530 and 550 nm fluorescence of Er 3+ -doped SrGdGa 3 O 7 single crystal have been studied for temperature sensing purposes. To achieve that, a simple experimental setup has been developed that consists of a 980 nm laser diode, two interference filters, two Si-photocells and two multimeters, while without use of monochromator or focusing lens for fluorescence collection. The study shows that the Er 3+ -doped SrGdGa 3 O 7 crystal displays strong green emission intensity (hence good signal-to-noise ratio) and high temperature sensitivity of fluorescence intensity ratio of the 530 and 550 nm emissions, which is (5.6–104.0) × 10 −3 K −1 in the considered temperature range 100–430 K, depending on the temperature. In addition, the experiments were repeated using a spectrometer and consistent results of temperature characteristics were obtained. Present study shows that the Er 3+ -doped SrGdGa 3 O 7 crystal is a promising host material for optical temperature sensing. [ABSTRACT FROM AUTHOR]

• Linear energy dispersion artifacts appear in XPEEM real space and reciprocal space imaging. • The observed non-isochromatism is shown to be mainly linear across the imaged field of view. • Non-isochromatism can be fully removed by a versatile data correction procedure. • The correction procedure can be tuned to reduce the noise level of XPEEM data at the cost of spectral resolution. • Noise level and spectral resolution of XPEEM data can be adjusted after data acquisition. Non-isochromatism in X-ray PhotoEmission Electron Microscopy (XPEEM) may result in unwanted artifacts especially when working with large field of views. The lack of isochromatism of XPEEM images may result from multiple factors, for instance the energy dispersion of the X-rays on the sample or the effect of one or more dispersive elements in the electron optics of the microscope, or the combination of both. In practice, the photon energy or the electron kinetic energy may vary across the image, complicating image interpretation and analysis. The effect becomes severe when imaging at low magnification upon irradiation with high energy photons. Such imaging demands for a large X-ray illuminating spot size usually achieved by opening the exit slit of the X-ray monochromator while reducing the monochromaticity of the irradiating light. However, we show that the effect is linear and can be fully removed. A versatile correction procedure is presented which leads to true monochromatic photoelectron images at improved signal-to-noise ratio. XPEEM data recorded at the nanospectroscopy beamline of the Elettra synchrotron radiation facility illustrate the working principle of the procedure. Also, reciprocal space XPEEM data such as angle-resolved photoelectron spectroscopy (ARPES) momentum plots suffer from linear energy dispersion artifacts which can be corrected in a similar way. Representative data acquired from graphene synthesized on copper by chemical vapor deposition prove the benefits of the correction procedure. [ABSTRACT FROM AUTHOR]

The 2nd-crystal systems based on the single-axis hinge or optimized cross-spring pivot are compared by theoretical analysis, finite element calculation and experimental test. To improve the vibration stability of the monochromator in synchrotron radiation, the overall vibration response characteristics and their effects on the crystal performance are analyzed. Results show (a) the cross-spring pivot provide better axial stability and higher axial stiffness than the single-axis hinge, (b) the first-order natural frequency of the angle adjustment mechanism with cross-spring pivot is increased by a factor of approximately 3.1, and (c) the first-order natural frequency of the whole 2nd-crystal system is increased by 45 %. The RMS value of the relative pitch angle vibration of the double crystals without cooling is improved by 12.6%, and is 83.6 nrad under liquid nitrogen cooling. The vibration stability of the 2nd-crystal system with cross-spring pivot is greatly improved, which provides a new research basis for further optimization of the 2nd-crystal system and monochromator. [ABSTRACT FROM AUTHOR]

• Low energy cyclotron analysis. • Wave mechanics of a cyclotron. • New radial cyclotron emission mode. • Cyclotron emission and high resolution electron spectroscopy. The influence of low energy bremsstrahlung emission on the performance of electron spectrometers and monochromators is investigated. Despite the occurrence of multi-photon events, the effect of the main azimuthal (organ pipe) mode is likely to be negligible. Potentially more serious is a new radial mode not considered in the classical theory but revealed in the quantum mechanics picture. The progress of the finely focused wave at the spectrometer entrance slit is described by a coherent wave packet of many oscillator states. It is shielded from disruption by a relatively much longer half-life. Cavity effects causing additional suppression of bremsstrahlung emission are briefly discussed. [ABSTRACT FROM AUTHOR]

A new monochromator with high spectral resolution in the extreme ultraviolet (XUV) has been developed for high-order laser harmonics selection. The system has three optical elements—a cylindrical (or spherical) focusing mirror, a uniform-line-spaced plane grating, and a plane mirror. The last element is required to maintain the focus on a fixed vertical slit when the grating subtended angle is changed in order to minimize the spectral defocusing aberration. The parameters of the focusing mirror are determined to introduce a coma that compensates for the coma given by the grating. The possibility of using two interchangeable gratings made the set-up optimized for a broad energy range of 12−50 eV. As a design test case, the set-up has been applied to a selection of the discrete spectral lines emitted by a gas-discharge lamp as the XUV source, obtaining a resolving power E/ Δ E > 3000.