Systematic measurements of M X-ray components X-ray fluorescence cross-sections for the elements with 77 ≤ Z ≤ 92 by employing laboratory source based energy dispersive X-ray fluorescence setup

The differential X-ray fluorescence (XRF) cross-sections for (Mξ₂, Mξ₁, Mδ₁), (Mδ₂, Mα_1,2 M₅-O₃), (Mβ, M₄-O_2,3), (Mγ, Mm₂, M₃-N₄, M₅-O_2,3), (Mm₁, M₃-N_6,7, M₃-O_4,5) and (Mm_2, M₂-N₆) group of M X-rays components have been measured for the elements with 77 ≤ Z ≤ 92 following photoionization by Mn K X-rays (E_Kαβ = 5.96 keV) obtained from ⁵⁵Fe radioisotope. The measurements were performed in annular source geometry at 126° emission angle using a low-energy Ge (LEGe) detector. The measured cross-section values are compared with theoretical values calculated using available sets of M_i (i = 1–5) photoionization cross-sections, radiative emission rates (F_ij), Coster-Kronig (f_ij), and fluorescence (ω_i) yields. The measured XRF cross-sections for the (Mξ₂, Mξ₁, Mδ₁), (Mm₁, M₃-N_6,7) and (Mm₂, M₂-N₆) groups of X-rays agree with the theoretical values within the experimental errors. The (Mβ, M₄-O_2,3) group of X-rays exhibit agreement with theoretical values within experimental uncertainty for all the elements under investigation except ₇₉Au and ₈₀Hg. The XRF cross-section for the (Mδ₂, Mα_1,2) group of X-rays are in general higher by ~20% for the elements with Z = 77–83 and exhibit agreement for the ₉₀Th and ₉₂U elements. For the (Mγ, Mm₂, M₃-N₄) X-ray group, the measured values are generally higher than the theoretical values, but the deviations are within experimental uncertainties. The large deviation in measured XRF cross-section for different M X-ray components from the theoretical ones are attributed to (i) poor separation of M X-ray components (ii) contribution of self-resonant Raman scattering (RRS) process and (iii) self-fluorescence of M₅ subshell by M_i subshell X-rays (i = 1–3).     

Application of Kβ/Kα in selecting calibration standards for X-ray fluorescence analysis

A method for improving the accuracy in X-ray fluorescence spectroscopy analysis with pressed pellets was established through matching the calibration standards by the Kβ/Kα ratios. The Kβ/Kα ratios of four major elements (Al, Si, Ca, and Fe) were measured in 14 certified reference materials (CRMs) for geochemistry. The deviation of the biggest Kβ/Kα values relative to the smallest ones for the same element was from 1.52% (Si) to 20.98% (Al) when pressed pellets were used. The relative deviation of Kβ/Kα values for Ca was as high as 3.56% even for two soil CRMs (GBW07404 and GBW07408). X-ray diffraction analysis confirmed that the Ca elements in the two CRMs were in distinct phases, thereby leading to the different Kβ/Kα values. The Fundamental Parameter Method (FPM) results of two calibration strategies were compared. When one of the 14 CRMs was selected as unknown sample whereas the other 13 CRMs were used for calibration to determine Al₂O₃, SiO₂, CaO, and Fe₂O₃, the relative errors were 10.80%, 8.77%, 8.33%, and 10.91%, respectively. Another strategy, where only one CRM was used for calibration of samples with large errors, was adopted by matching Kβ/Kα values. The results of calibrating using CRM with similar Kβ/Kα values were more accurate than those with different Kβ/Kα values.     

Measurement ofK αcross sections and fluorescence yields for elements in the range 42≦Z≦57 using radioisotope X-ray fluorescence

TheK x-ray fluorescence (XRF) cross sections have been experimentally determined for elements in the range 42Z57 at excitation energy of 59.54keV associated with gamma rays of Am-241 radioisotope. In addition, measurements of XRF yields of theK shell (w _k) for the same elements at the same excitation energy have also been carried out. Our measurements were shown to agree with theoretical calculations.     

Infrared thermography for condition monitoring – A review

Temperature is one of the most common indicators of the structural health of equipment and components. Faulty machineries, corroded electrical connections, damaged material components, etc., can cause abnormal temperature distribution. By now, infrared thermography (IRT) has become a matured and widely accepted condition monitoring tool where the temperature is measured in real time in a non-contact manner. IRT enables early detection of equipment flaws and faulty industrial processes under operating condition thereby, reducing system down time, catastrophic breakdown and maintenance cost. Last three decades witnessed a steady growth in the use of IRT as a condition monitoring technique in civil structures, electrical installations, machineries and equipment, material deformation under various loading conditions, corrosion damages and welding processes. IRT has also found its application in nuclear, aerospace, food, paper, wood and plastic industries. With the advent of newer generations of infrared camera, IRT is becoming a more accurate, reliable and cost effective technique. This review focuses on the advances of IRT as a non-contact and non-invasive condition monitoring tool for machineries, equipment and processes. Various conditions monitoring applications are discussed in details, along with some basics of IRT, experimental procedures and data analysis techniques. Sufficient background information is also provided for the beginners and non-experts for easy understanding of the subject.     

X-ray fluorescence analysis of Ni–Fe–Mn/Cr systems

We have developed a procedure for x-ray fluorescence determination of the constituent composition and thickness of two-layer Ni–Fe–Mn/Cr films deposited on Polikor, an aluminum oxide ceramic. We have calculated correction coefficients taking into account interelement interference effects in this system. We have experimentally determined the density of the materials making up the composition of the films. We have established and present the metrological characteristics of the procedure developed.     

Non-destructive and in situ analysis of Egyptian wall paintings by X-ray diffraction and X-ray fluorescence portable systems

The concurrence and complementarities of obtained images under various wavelengths and the elemental and structural analyses provided by XRF and XRD, using portable non-invasive systems, have allowed for obtaining accurate data about the employed pictorial technique in two Egyptian wall paintings dating from the New Kingdom. Thus, compounds such as Egyptian blue, Egyptian green, goethite, jarosite, hematite, calcite, anhydrite or huntite have been detected in the paintings. The performance of the measurements by the different techniques and its contribution to the knowledge of the materials are discussed. They notably give a clue on the origin of arsenic compounds, unexpectedly detected in some decors.     

XAFS spectra from X-ray fluorescence Kβ line using conventional energy-discriminating detector

X-ray fluorescence spectra of copper (Cu) metal, copper monoxide (CuO), and potassium chromate (K₂CrO₄) were recorded as a function of incident X-ray energy near the Cu K-edge and chromium (Cr) K-edge, respectively, using a conventional silicon drift detector. The spectra contained components due to elastic, inelastic, and multiple scattering, in addition to the Kα and Kβ lines. Cu and Cr K-edge X-ray absorption fine structure (XAFS) spectra of Cu, CuO, and K₂CrO₄ were obtained by an intensity analysis of the Kα and Kβ lines. The intensity of the Kβ line for the different incident photon energies was obtained by numerically removing the additional scattering components using the MUSCAT program. These spectra exhibited a jump near the K absorption edges, which reproduced the spectral features obtained in transmission mode for both Cu, CuO, and K₂CrO₄. A chemical shift was also clearly identified in the X-ray absorption near edges structure using the X-ray fluorescence Kβ line. In addition, the Cr K-edge extended XAFS spectrum of K₂CrO₄ was clearly observed using the Cr Kβ fluorescent line. The XAFS measurements on the Kα and Kβ lines are possible, and they carry equally valuable information.     

Infrared magnetooptic — A tool for the determination of the effective mass

The analysis of the magnetooptical effects of heavily doped materials at the plasma edge yields the concentration dependence of the effective cyclotron mass. Therefore these experiments support the general diskussion about the nonparabolicity of a band, the position of the Fermi level at high degenerated semiconductors and the determination of the dispersion function. Experimental results of the magnetooptical determinedm _c ^* (N) function are compared with coresponding band structure calculations. A matrix calculation model, which describes the symmetrical magnetooptical transmission effects as well as the asymmetrical magnetooptical reflection effects of arbitrary successions of coherent films and incoherent substrates consitently, is used to determine free carrier density profilesN (z) of inhomogeneously doped semiconductors non-destructively. This application of the matrix formalism requires the knowledge of them ^* (N)-function. The influence of the effective cyclotron mass on thedifferential magnetooptical interference structures caused by buried density profiles is discussed.     

Malus’ law for X-ray radiation

Light propagation through a polarizer-analyzer system is investigated on the basis of quantum concepts about the nature of light. It is shown that Malus’ law, which is based on principles of classical electrodynamics, does not fully take into account all effects that can arise under light propagation through a polarizer-analyzer system. In particular, the phenomenon of a possible change in the light frequency is not considered, e.g., in the case of X-ray radiation. The derivation of Malus’ law based on quantum principles is presented. For comparison, the differential effective cross section of the interaction between a photon and an electron is found taking into account rotation of the photon polarization plane in the Compton effect.     

Linear scheme for time-domain fluorescence molecular tomography

Based on the generalized pulse spectrum technique that was previously developed for time-domain diffuse optical tomography, we propose a linear framework of time-domain fluorescence molecular tomography for simultaneous reconstruction of both the yield and lifetime of multi-fluorophores. The methodology is exemplified for mono-component case and validated with simulated data.     

In situ demineralisation of human enamel studied by synchrotron-based X-ray microtomography – A descriptive pilot-study

An in situ study was designed to investigate naturally developed demineralisation in human enamel in a widely non-destructive manner in combination with X-ray microtomography. Samples of human enamel were carried in the oral cavity of participants for 24 h daily for either 21 or 29 days using so-called intraoral mandibular appliances (ICTs). Demineralisation was thereby generated in a natural way without causing caries in the subjects’ dentition. By employing synchrotron-based X-ray microtomography (XMT) in combination with volume image analysis, a quantification and three-dimensional visualisation of different stages of mineral density loss was possible. Basic features of the demineralised samples were similar to those reported in earlier in vitro studies. However, the analysed samples showed significant differences in the morphology of surface attack and the degree of mineral density loss depending on the carrier, the exposure time and the position within the ICT. In particular, the varying local conditions within a carrier's oral cavity seem to be different than in an in vitro study. Our results show that the combination of ICTs and quantitative image analysis applied to XMT data provides an analytical tool which is highly suited for the fundamental investigation of naturally developed demineralisation processes.     

L X-ray fluorescence cross sections and yields for mediumZ elements in the energy region 5.47 ≤E ≤ 9.36 keV

TotalL X-ray fluorescence cross sections have been measured in the atomic region 39 Z 51 excited by 5.47, 6.47, 7.04, 7.57, 8.14, 8.74 and 9.36 keV photons. Experimental cross sections are compared with the theoretical estimates of Chen et al. based on relativistic Dirac-Hartree-Slater theory. Good agreement is observed between experimental results and theoretical estimates in the studied atomic and energy region. Experimental fluorescence yields have been evaluated using the experimental fluorescence cross sections and theoretical subshell photoionization cross sections. Fluorescence yields are fitted by least squares to fifth-order polynomials inZ of the form _n a _n z ⁿ and compared with theoretical and earlier fitted values. The deviation of the average fluorescence yield in the atomic region 46Z 51 with new theoretical estimates of , calculated using the ECPSSR (Energy loss Coulomb deflection Perturbed Stationary State Relativistic effects) theory of Brandt and Lapicki and the fitted values clearly indicate the weak dependence of the average fluorescence yield on the initial vacancy distribution.     

Solid-state NMR: A powerful tool for characterization of metal–organic frameworks

Metal–organic frameworks (MOFs) are a new type of porous materials with numerous current and potential applications in many areas including ion-exchange, catalysis, sensing, separation, molecular recognition, drug delivery and, in particular, gas storage. Solid-state NMR (SSNMR) has played a pivotal role in structural characterization and understanding of host–guest interactions in MOFs. This article provides an overview on application of SSNMR to MOF systems.     

X-ray absorption spectroscopy in biology – present and future

From May 10 to 12, the GISAXS Workshop 2005 was hosted at HASYLAB/DESY in Hamburg, Germany. GISAXS stands for Grazing Incidence Small Angle X-ray Scattering, a surface-sensitive technique to observe structures on large length scales up to several hundred nanometers. Organized by R. Gehrke and S. V. Roth from HASYLAB and P. Müller-Buschbaum from University of Technology Munich, the workshop attracted more than 50 participants from all over the world, originating a very stimulating atmosphere with invited talks, a contributed poster session and practical training, including real data acquisition at the beamline BW4.     

A high velocity resolution M?ssbauer spectrometric system for biomedical research

An automated high-precision M?ssbauer spectrometric system with a high velocity resolution for biomedical research is described. The results from testing the system are given. Applications of M?ssbauer spectrometric system in the study of iron-containing proteins in normal and pathological cases demonstrate the possibilities for obtaining new data.     

X-ray calculations for a NLTE Ar plasma

A model is developed to calculate emission spectrum of non-local thermodynamic equilibrium(NLTE) plasmas. The Collisional-Radiative model is adopted for non-LTE population calculations. Configuration-averaged rate coefficients that needed in the rate equations are obtained based on the first order perturbation theory. The Hatree-Fock-Slater self-consistent-field method is used to calculate electron wave functions. The present model is applied to the calculation of emissivity from a Ar plasma. The features of the spectra are in good agreement with those calculated by other theoretical models, but the data of the integrated emissivity differ by a factor 2～8.     

Characterization of the Carancas�CPuno meteorite by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission M?ssbauer spectroscopy

We report the results of the study of a meteorite that impacted an inhabited zone on 15 September 2007 in the neighborhood of the town of Carancas, Puno Region, about 1,300 km south of Lima. The analysis carried out by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission Mössbauer spectroscopy (at room temperature and at 4.2 K), reveal the presence in the meteorite sample of magnetic sites assigned to taenite (Fe,Ni) and troilite (Fe,S) phases, and of two paramagnetic doublets assigned to Fe^2?+?, one associated with olivine and the other to pyroxene. In accord with these results, this meteorite is classified as a type IV chondrite meteorite.     

A portable X-ray diffraction apparatus for in situ analyses of masters’ paintings

It is rare that the analyses of materials in paintings can be carried out by taking micro-samples. Valuable works of art are best studied in situ by non-invasive techniques. For that purpose, a portable X-ray diffraction and fluorescence apparatus has been designed and constructed at the C2RMF. This apparatus has been used for paintings of Rembrandt, Leonardo da Vinci, Van Gogh, Mantegna, etc. Results are given to illustrate the performance of X-ray diffraction, especially when X-ray fluorescence does not bring sufficient information to conclude.     

A median-Gaussian filtering framework for Moiré pattern noise removal from X-ray microscopy image

Moiré pattern noise in Scanning Transmission X-ray Microscopy (STXM) imaging introduces significant errors in qualitative and quantitative image analysis. Due to the complex origin of the noise, it is difficult to avoid Moiré pattern noise during the image data acquisition stage. In this paper, we introduce a post-processing method for filtering Moiré pattern noise from STXM images. This method includes a semi-automatic detection of the spectral peaks in the Fourier amplitude spectrum by using a local median filter, and elimination of the spectral noise peaks using a Gaussian notch filter. The proposed median-Gaussian filtering framework shows good results for STXM images with the size of power of two, if such parameters as threshold, sizes of the median and Gaussian filters, and size of the low frequency window, have been properly selected.     

Characterization and comparison of X-ray focusing optics for ultrafast X-ray diffraction experiments

We have characterized and compared the performance of different types of multi-layer optics for the focusing of femtosecond X-ray pulses. Using X-ray pulses at 8 keV, from a laser-driven plasma source we have measured the spatial distribution of the diffracted X-rays directly after and in the focal plane of the various X-ray optical devices. For a Montel optic with 7.3× magnification we obtained the largest number of focused X-ray photons per unit angle. The performance of this optic in the X-ray diffraction experiment on a thin germanium film is demonstrated.