Double Crystal Spectrometer Research Articles

Natural linewidths of Cu Kα1,2 spectra obtained with an antiparallel double-crystal X-ray spectrometer

An investigation of Cu Kα X-ray emission spectra, together with their satellite lines, using both experimental techniques and theoretical calculations, provides accurate values for the natural linewidths and other parameters of the emission lines.

Calculation of the Rocking Curve of a Double-Crystal Neutron Spectrometer on Strongly Absorbing InSb Crystals in Laue–Laue Geometry

Calculation of the Rocking Curve of a Double-Crystal Neutron Spectrometer on Strongly Absorbing InSb Crystals in Laue–Laue Geometry

Rocking Curve of a Double-Crystal Spectrometer in the Bragg–Bragg Geometry Including the Absorption Coefficient Dependency from the Neutron Wavelength

Rocking Curve of a Double-Crystal Spectrometer in the Bragg–Bragg Geometry Including the Absorption Coefficient Dependency from the Neutron Wavelength

ROCKING CURVE OF A DOUBLE-CRYSTAL SPECTROMETER IN THE BRAGG-BRAGG GEOMETRY INCLUDING THE ABSORPTION COEFFICIENT DEPENDENCY FROM THE NEUTRON WAVELENGTH

An analytical expression is obtained for the rocking curve of a double-crystal spectrometer, which does not require restrictions on the absorption cross section dependency on the wavelength. A modeled rocking curve (instrumental line) for the Bragg–Bragg spectrometric scheme is calculated using the example of an InSb crystal in the region of weak dependency between the absorption cross section and the wavelength and in the region of wavelengths close to the absorption resonance.

Absolute measurement of the relativistic magnetic dipole transition in He-like sulfur

We have made an absolute, reference-free measurement of the $1s2s\phantom{\rule{0.28em}{0ex}}^{3}S_{1}\ensuremath{\rightarrow}1{s}^{2}\phantom{\rule{0.28em}{0ex}}^{1}S_{0}$ relativistic magnetic dipole transition in He-like sulfur. The highly charged sulfur ions were provided by an electron-cyclotron resonance ion source, and the x rays were analyzed with a high-precision double-crystal spectrometer. A transition energy of 2430.3685(97) eV was obtained and is compared to most advanced bound-state quantum electrodynamics calculations, providing an important test of two-electron QED effects and precision atomic structure methods in medium-$Z$ species. Thanks to the extremely narrow natural linewidth of this transition and to the large dispersion of the spectrometer at this energy, a complementary study is also performed to evaluate the impact of different silicon crystal atomic form-factor models in the transition-energy analysis. We find no significant dependence on the model used to determine the transition energy.

Intensity Ratio of Kβ/Kα in Selected Elements from Mg to Cu, and the Chemical Effects of Cr Kα1,2 Diagram Lines and Cr Kβ/Kα Intensity Ratio in Cr Compounds

Kα,β X-ray lines from photon excitation were measured in selected elements from Mg to Cu using a high-resolution double-crystal X-ray spectrometer with a proportional counter, and the Kβ/Kα intensity ratio for each element was obtained, after correcting for self-absorption, detection efficiency, and crystal reflectance. This intensity ratio increases rapidly from Mg to Ca but, in the 3d elements region, the increase becomes slower. This is related to the intensity of the Kβ line involving valence electrons. The slow increase of this ratio in the 3d elements region is thought to be due to the correlation between 3d and 4s electrons. Moreover, the chemical shifts, FWHM, asymmetry indices, and Kβ/Kα intensity ratios of the Cr compounds, due to different valences, were also investigated using the same double-crystal X-ray spectrometer. The chemical effects were clearly observed, and the Kβ/Kα intensity ratio was found to be compound-dependent for Cr.

The NIST Vacuum Double-Crystal Spectrometer: A Tool for SI-Traceable Measurement of X-Ray Emission Spectra.

The NIST Vacuum Double-Crystal Spectrometer (VDCS) has been modernized and is now capable of recording reference-free wavelength-dispersive spectra in the 2 keV to 12 keV x-ray energy range. The VDCS employs crystals in which the lattice spacings are traceable to the definition of the meter through x-ray optical interferometry with a relative uncertainty ﹤10-⁸. VDCS wavelength determination relies upon precision angle difference measurements for which the encoders of the rotation stages have been calibrated using the circle closure method for accurate, absolute angle measurement. The new vacuum-compatible area detector allows quantification of the aberration functions contributing to the observed line shape and in situ alignment of the crystal optics. This latter procedure is augmented with the use of a thin lamella as the first crystal. With these new techniques, x-ray spectra are registered with the VDCS on an absolute energy scale with a relative uncertainty of 10-⁶.

Structure of single KL0–, double KL1–, and triple KL2 − ionization in Mg, Al, and Si targets induced by photons, and their absorption spectra

We investigated experimentally and theoretically x-ray properties of Mg, Al and Si to assess for new reliable x-ray useful quantities. We measured the KL0– diagram, and KL1– and KL2– satellite lines in Mg, Al, and Si, ionized by photon excitation, using a high-resolution anti-parallel double-crystal x-ray spectrometer. Their energy values, full width at half maxima (FWHM), and relative intensities are obtained by the multiple fitting methods and compared with those reported by other excitation processes. It was found that the relative intensity of Mg and Si KL1 and KL2 satellite lines to the KL0 diagram lines depend on the method used to produce the K hole. The evidence of a new transition between Kα3 and Kα4 in Mg, Al, and S KL1 satellite lines is suggested. These x-ray diagram and satellite lines were investigated theoretically and we found that Mg Kα1,2 diagram lines with hidden satellites are especially in very good agreement with the corresponding experimental ones. Moreover, we also determined the mass attenuation coefficients in a wide energy range covering the K-absorption edge, including a detailed evaluation of the associated uncertainties. From the absorption spectra of Mg and Al, the cross sections of the multi-electron transition processes were estimated and match the theoretical values.

A double crystal von Hamos spectrometer for traceable x-ray emission spectroscopy.

A novel double full-cylinder crystal x-ray spectrometer for x-ray emission spectroscopy (XES) has been realized based on a modified von Hamos geometry. The spectrometer is characterized by its compact dimensions, its versatility with respect to the number of crystals used in series in the detection path, and the option to perform calibrated XES measurements. The full-cylinder crystals used are based on highly annealed pyrolytic graphite with a thickness of 40μm, which was bent to a radius of curvature of 50mm. The flexible designof the spectrometer allows for an easy change-within the same setup-between measurements with one crystal for maximized efficiency or two crystals for increased spectral resolving power. The spectrometer realized can be used at different end-stations of synchrotron radiation beamlines or can be laboratory-based. The main application focus of the spectrometer is the determination of x-ray fundamental atomic parameters in the photon energy range from 2.4 to 18keV. The evaluation of chemical speciation is also an area of application, as demonstrated in the example of battery electrodes using resonant inelastic x-ray scattering.

Sulfur accumulation in soil in a forested watershed historically exposed to air pollution in central Japan

Forest soils that have accumulated anthropogenic sulfur (S) as a result of historical air pollution may gradually or suddenly release inorganic sulfate either by desorption of inorganic sulfate or by mineralization of organic S, even after mitigation of previous air pollution. The release of inorganic sulfate from soil to surface water leads directly to watershed acidification. Thus, whether the organic S compounds that have accumulated in soils are resistant to microbial activity, due to formation of organo-mineral complexes, is essential information for management of forest soil ecosystem services. A nationwide air pollution monitoring survey by the Japanese Ministry of the Environment identified acidification of both surface water and soil in the Lake Ijira watershed of central Japan, presumably sourced from the Chukyo Industrial Area which lies upwind of the watershed. We compared the amount of S accumulated in the Ijira soils (Dystrudepts) with that in comparable soils in other watersheds in central Japan that were less affected by industrial air pollution. To determine how much mineral-associated organic S had accumulated in the Ijira soils, we measured pyrophosphate- extractable S. We used high-resolution x-ray fluorescence (HRXRF) spectroscopy with a double-crystal type high energy resolution spectrometer to estimate the oxidation states of both mineral-associated and free organic S. We also measured S isotope compositions to explore S dynamics in the soils. We found that more S had accumulated in the Ijira soils than in the comparable soils from other watersheds in central Japan. Concentrations of total S in the Ijira soils varied among soil horizons, reaching more than 1000 mg S kg−1 in some horizons. Mineral-associated organic S accounted for more than half of the total accumulated S. High-resolution x-ray fluorescence spectrum analyses showed that mineral-associated organic S was retained at both high and low oxidation states. The δ34S values of total S in the deeper horizons tended to be higher than those of the uppermost horizons of the Ijira soils and correlated positively with concentrations of extractable Al and Fe oxides (which characterize pedogenic minerals). Our results suggest that about half of total accumulated S in Ijira soils is stabilized in pedogenic minerals and the remainder comprises free organic S and adsorbed inorganic sulfates. There might have been repetitive mobilization and immobilization of S and the degraded organic S might have greater affinity with pedogenic minerals. Further, the ratio of total C to mineral-associated organic S correlated negatively with concentrations of extractable Al and Fe oxides, suggesting that organic S is more resistant to mineralization than organic C because S is preferentially associated with the pedogenic minerals. Monitoring of the chemical states of S compounds in soils historically exposed to air pollution is recommended to assist in prediction of the fate of the S compounds that have accumulated in them.

Structure of Kα1,2 - and Kβ1,3 -emission x-ray spectra for Se, Y, and Zr

The $K\ensuremath{\alpha}$ and $K\ensuremath{\beta}$ x-ray spectra of Se, Y, and Zr were studied experimentally and theoretically in order to obtain information on the $K{\ensuremath{\alpha}}_{1}$ line asymmetry and the spin doublet in $K{\ensuremath{\beta}}_{1,3}$ diagram lines. Using a high-resolution antiparallel double-crystal x-ray spectrometer, we obtained the line shapes, that is, asymmetry index and natural linewidths. We found that the corrected full width at half maximum of the $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines as a function of $Z$ is in good agreement with the data in the literature. Furthermore, satellite lines arising from shake-off appear in the low-energy side of the $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines in Se but, in Y and Zr, it was very difficult to identify the contribution of the shake process to the overall lines. The $K{\ensuremath{\beta}}_{1,3}$ natural linewidth of these elements was also corrected using the appropriate instrumental function for this type of x-ray spectrometer, and the spin doublet energies were obtained from the peak positions. The corrected full width at half maximum (FWHM) of the $K{\ensuremath{\beta}}_{1}$ x-ray lines increases linearly with $Z$, but this tendency was found to be, in general, not linear for $K{\ensuremath{\beta}}_{3}$ x-ray lines. This behavior may be due to the existence of satellite lines originated from shake processes. Simulated line profiles, obtained using the multiconfiguration Dirac-Fock formalism, accounting for radiative and radiationless transitions and shake-off processes, show a very good agreement with the high-resolution experimental spectra.

The molybdenum K-shell x-ray emission spectrum**Official contribution of the National Institute of Standards and Technology; not subject to copyright in the United States.

We present newly measured spectra of the x-ray emission of a molybdenum metal anode subject to electron bombardment, using a very high dispersion silicon double-crystal spectrometer. The measurement includes the dipole-allowed KL, KM, and KN emission lines, based on an energy scale traceable to the Système International definition of the meter with a systematic uncertainty below . The data are presented as parametrized multi-Lorentzian fits to the results, and as supplementary data with the complete spectrum of each line group, corrected for instrumental effects. The () line energy was in complete statistical agreement with published measurements, and it showed no asymmetry. Other lines showed varying discrepancies with the literature which lie outside the bounds of probable experimental errors.

Precise x-ray energies of gadolinium determined by a combined experimental and theoretical approach

We combined different experimental techniques with a theoretical approach to determine a consistent set of diagram lines energies and binding energies. We propose an original approach consisting in determining the mass attenuation coefficients in an energy range covering the L-, M- and N- absorption edges, including a detailed evaluation of the associated uncertainties, to derive precisely the binding energies. We investigated the Lα, Lβ and M spectra of Gd with an independantly calibrated high-resolution anti-parallel double-crystal x-ray spectrometer. All the lines were identified and found in excellent agreement with the binding energies previously derived. Morever, we identified for the first time M5−O2,M4−O2,3 and M4−N2,3 diagram lines.

Valence-to-core XES of Ti, TiO and TiO2 by means of a double crystal von Hamos spectrometer

Valence-to-core XES of Ti, TiO and TiO2 by means of a double crystal von Hamos spectrometer

Valence-to-core XES of Ti, TiO and TiO2 by means of a double full-cylinder crystal von Hamos spectrometer.

We present valence-to-core x-ray emission spectroscopy of Ti, TiO and TiO2 by means of a double crystal von Hamos spectrometer based on full-cylinder highly-annealed pyrolytic graphite mosaic crystals. We demonstrate that, using a double crystal configuration, an energy resolution of E/ΔE ≈ 2700 can be achieved in a compact setup using cylindrically curved optics with a radius of curvature of 50 mm. The stated energy resolution proved to be high enough to identify and determine chemical shifts of the Kβ2,5 and Kβ" emission lines of both oxides. The experimental results are supported by calculations with the ab initio package OCEAN and compared to literature values.

Valence-to-core XES of Ti, TiO and TiO2 by means of a double crystal von Hamos spectrometer

Valence-to-core XES of Ti, TiO and TiO2 by means of a double crystal von Hamos spectrometer

Dispersive refraction of different light to heavy materials at MeV γ -ray energies

The dispersive behavior of materials with atomic charge numbers varing from $Z = 4$ (beryllium, Be) to $Z = 82$ (lead, Pb) was investigated experimentally and theoretically at $\gamma$-ray energies up to 2 MeV. The experiment was performed at the double-crystal gamma spectrometer GAMS6 of the ILL in Grenoble. The experimental results were compared with theoretical calculations which account for all major elastic processes involved. Overall, we found a good agreement between theory and experiment. We find that for the development of refractive optics at $\gamma$-ray energies beyond those currently in use high-Z materials become increasingly attractive compared to the beryllium lens-stacks used at X-ray energies.

Structure of high-resolution Kβ1,3 x-ray emission spectra for the elements from Ca to Ge

The $K\ensuremath{\beta}$ x-ray spectra of the elements from Ca to Ge have been systematically investigated using a high-resolution antiparallel double-crystal x-ray spectrometer. Each $K{\ensuremath{\beta}}_{1,3}$ natural linewidth has been corrected using the instrumental function of this type of x-ray spectrometer, and the spin doublet energies have been obtained from the peak position values in $K{\ensuremath{\beta}}_{1,3}$ x-ray spectra. For all studied elements the corrected $K{\ensuremath{\beta}}_{1}$ x-ray lines FWHM increase linearly as a function of $Z$. However, for $K{\ensuremath{\beta}}_{3}$ x-ray lines this dependence is generally not linear in the case of $3d$ elements but increases from Sc to Co elements. It has been found that the contributions of satellite lines are considered to be $[KM]$ shake processes. Our theoretically predicted synthetic spectra of Ca, Mn, Cu, and Zn are in very good agreement with our high-resolution measurements, except in the case of Mn, due to the open-shell valence configuration effect (more than 7000 transitions for diagram lines and more than $100\phantom{\rule{0.16em}{0ex}}000$ transitions for satellite lines) and the influence of the complicated structure of the metallic Mn.

Refractive-index measurement of Si at γ -ray energies up to 2 MeV

The refractive index of silicon at $\gamma$-ray energies from 181 - 1959 keV was investigated using the GAMS6 double crystal spectrometer and found to follow the predictions of the classical scattering model. This is in contrast to earlier measurements on the GAMS5 spectrometer, which suggested a sign-change in the refractive index for photon energies above 500 keV. We present a re-evaluation of the original data from 2011 as well as data from a 2013 campaign in which we show that systematic errors due to diffraction effects of the prism can explain the earlier data.

Kα1,2x-ray linewidths, asymmetry indices, and[KM]shake probabilities in elements Ca to Ge and comparison with theory for Ca, Ti, and Ge

We have investigated systematically the $K\ensuremath{\alpha}$ x-ray spectra in elements from Ca to Ge within Berger's two-Lorentzian functions model, using a high-resolution antiparallel double-crystal x-ray spectrometer, in order to obtain in detail the physical meaning of the asymmetry in the spectral profiles. The overall tendency of the corrected full width at half maximum of the $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines as a function of $Z$, as well as the linewidths, are in good agreement with the data reported in the literature. It is found, from both the experiments and calculation, that satellite lines arising from shake-off appear between the $K{\ensuremath{\alpha}}_{1}$ and $K{\ensuremath{\alpha}}_{2}$ lines. The asymmetry index of $K{\ensuremath{\alpha}}_{1}$ in $3d$ elements from Sc to Zn is ascribed to the existence of a $3d$ spectator hole. Moreover, the observed Sc $K{\ensuremath{\alpha}}_{1}$ line shows a symmetric profile unlike the Ti $K{\ensuremath{\alpha}}_{1}$ line profile, this discrepancy being explained by the existence of satellite lines on both sides of the Sc profile. Our experimental results yielded around 25% probability for the probability of shake processes creating a second hole in the $3p$ or $3d$ subshells in Sc and around 18% probability for creating a second hole the in the $3p$ in Ca. For the latter process our calculated value, using multiconfiguration Dirac-Fock wave functions and the sudden approximation yielded a 10% probability.