X-ray spectrometry using polycapillary X-ray optics and position sensitive detector

Polycapillary X-ray optics (capillary X-ray lens) are now popular in X-ray fluorescence (XRF) analysis. Such an X-ray lens can collect X-rays emitted from an X-ray source in a large solid angle and form a very intense X-ray microbeam which is very convenient for microbeam X-ray fluorescence (MXRF) analysis giving low minimum detection limits (MDLs) in energy dispersive X-ray fluorescence (EDXRF). A new method called position sensitive X-ray spectrometry (PSXS) which combines an X-ray lens used to form an intense XRF source and a position sensitive detector (PSD) used for wavelength dispersive spectrometry (WDS) measurement was developed recently in the X-ray Optics Laboratory of Institute of Low Energy Nuclear Physics (ILENP) at Beijing Normal University. Such a method can give high energy and spacial resolution and high detection efficiency simultaneously. A short view of development of both the EDXRF using a capillary X-ray lens and the new PSXS is given in this paper.     

Development of confocal micro X-ray fluorescence instrument using two X-ray beams

A new confocal micro X-ray fluorescence instrument was developed. This instrument has two independent micro X-ray tubes with Mo targets. A full polycapillary X-ray lens was attached to each X-ray tube. Another half polycapillary lens was attached to a silicon drift X-ray detector (SDD). The focal spots of the three lenses were adjusted to a common position. The effects of the excitation of two X-ray beams were investigated. The instrument enabled highly sensitive three-dimensional X-ray fluorescence analysis. We confirmed that the X-ray fluorescence intensity from the sample increased by applying the two independent X-ray tubes in confocal configuration. Elemental depth profiling of black wheat was demonstrated with the result that each element in the surface coat of a wheat grain showed unique distribution.     

Identification of steel by X-ray fluorescence analysis with a pyroelectric X-ray generator

An application of X-ray fluorescence analysis with a pyroelectric X-ray generator is presented. Steel standard samples were identified by X-ray fluorescence analysis with this novel X-ray generator to check its capability for performing qualitative and quantitative analysis as an X-ray source for X-ray fluorescence spectrometers. Cr, Ni, V, Co, and W were detected in steel standard samples. V and Cr can be detected even when the content is below 1%. Although it is difficult to detect minor elements because of the low power of the excitation X-rays, it is possible to identify the analyzed samples on the basis of major elements at the percentage level. The pyroelectric X-ray generator is very suitable for portable X-ray fluorescence spectrometers.     

X-ray energy dependence of the properties of the focused beams produced by polycapillary X-ray lens

We investigated X-ray energy distribution in an X-ray microbeam produced by a polycapillary X-ray lens in combination with a sealed-type X-ray tube. This polycapillary X-ray lens has an output focal distance (OFD) of approximately 15 mm. The size of the X-ray microbeam and its OFD were estimated by using a wire scanning method. In our case, the sizes of the X-ray microbeams at the output focal distance were 49 microm for Mo L(alpha), 36 microm for W L(alpha), and 28 microm for Mo K(alpha). The spot sizes depend on the energy of the X-ray fluorescence. The reason for the energy dependence is that X-ray capillary optics is based on the principle of propagation through glass capillaries by means of X-ray total external reflection. The evaluated OFD values of Mo L(alpha) and Mo K(alpha) were slightly changed in 17 microm. However, a deviation of 100 microm from the OFD caused only a 3% increase of the focal spot size. Therefore, we concluded that the OFD showed no significant dependence on X-ray energy.     

Picosecond Time Resolved Hard X-Ray Diffraction from Laser Heated Metallic Crystals

We report the development of a novel hard X-ray diffraction system with picosecond time resolution. Picosecond X-ray pulses are produced by excitation of an X-ray diode with picosecond ultraviolet light pulses at a repetition rate of 300 Hz. The X-ray pulses are synchronized to the optical pulses with picosecond accuracy. The system has been utilized in picosecond time resolved X-ray diffraction of laser pulse heated gold and platinum single crystals.     

X-ray fluorescence imaging with polycapillary X-ray optics

X-ray fluorescence spectrometry imaging is a powerful tool to provide information about the chemical composition and elemental distribution of a specimen. X-ray fluorescence spectrometry images were conventionally obtained by using a μ-X-ray fluorescence spectrometry spectrometer, which requires scanning a sample. Faster X-ray fluorescence spectrometry imaging would be achieved by eliminating the process of sample scanning. Thus, we developed an X-ray fluorescence spectrometry imaging instrument without sample scanning by using polycapillary X-ray optics, which had energy filter characteristics caused by the energy dependence of the total reflection phenomenon. In the present paper, we show that two independent straight polycapillary X-ray optics could be used as an energy filter of X-rays for X-ray fluorescence. Only low energy X-rays were detected when the angle between the two optical axes was increased slightly. Energy-selective X-ray fluorescence spectrometry images with projection mode were taken by using an X-ray CCD camera equipped with two polycapillary optics. It was shown that Fe Kα (6.40 keV) and Cu Kα (8.04 keV) could be discriminated for Fe and Cu foils.     

X射线成像技术在能源材料研究中的应用

随着人类对可持续能源的需求不断增长,先进的表征方法在能源材料研究等领域变得越来越重要。借助X射线成像技术,我们可以从二维和三维角度实时获取能源材料的形貌、结构和应力变化信息。此外,借助高穿透性X射线和高亮度同步辐射源,设计原位实验,可以获取充放电过程中样品的定性和定量变化信息。本文综述了基于同步加速器的X射线成像技术及其相关应用,讨论了包括X射线投影成像、透射式X射线显微成像、扫描透射X射线显微成像、X射线荧光显微成像以及相干衍射成像等几种主要的X射线成像技术在能源材料研究领域的应用,展望了未来X射线成像的应用前景及发展方向。     

X-ray absorption spectral analysis with a 9 V battery X-ray generator.

X-ray absorption spectral (XAS) analysis is performed with a combination of a 9 V dry electric battery X-ray generator and a portable Si PIN X-ray detector. The calcium K edge (4.0 keV) in paper is measured with a grazing incidence geometry, which suppressed the artifact due to the Kalpha X-ray fluorescence peak at 3.5 keV. The 9 V dry battery X-ray emitter is useful for portable XAS measurements.     

Grazing-exit electron probe X-ray microanalysis (GE-EPMA): Fundamental and applications

Electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) has been studied under grazing-exit conditions. That is, characteristic X-rays are detected at a very small take-off (exit) angle; the technique is known as grazing-exit electron probe microanalysis (GE-EPMA). Fundamental aspects, instrumentation, and characteristics of grazing-exit electron probe X-ray microanalysis method are described here. Since the observation depth decreases as the exit angle decreases, theoretically to a few nanometers, surface analysis is possible in grazing-exit electron probe X-ray microanalysis. Of course, the size of the electron beam is also small—less than 1 μm, enabling localized surface analysis. In the case of total reflection X-ray spectrometry that allows surface analysis, the whole sample surface must be flat. However, the requirement for flatness is not as strict in grazing-exit electron probe X-ray microanalysis. Grazing-exit electron probe X-ray microanalysis measurements can easily be applied using a commercially available electron probe microanalysis (or Scanning electron microscope-energy dispersive X-ray spectrometry) instrument. To change and control the exit angle in grazing-exit electron probe X-ray microanalysis, the inclination of the sample stage or movement of the X-ray detector is all that is required. Theoretically, this study shows that grazing-exit electron probe X-ray microanalysis would be useful in improving the lateral resolution of the sample surface. In addition, the study demonstrates that grazing-exit electron probe X-ray microanalysis can be applied successfully for surface, thin-film, and particle analyses. As an optional method of electron probe microanalysis, grazing-exit electron probe X-ray microanalysis will be useful in expanding the research fields of normal electron probe microanalysis.     

An increase of utilization efficiency of X-ray beam

The features of absorbed dose field formation in objects irradiated with scanned X-ray beams at double—and four-sided irradiation were investigated both analytically and by Monte Carlo methods. An analytical approach uses an angular/spectrum X-ray characteristics calculated with PENELOPE, JEANT 4 and ModeXR codes. It was shown that the special angular orientation of electron beam incidence on the X-ray converter leads to X-ray dose smoothing on the surface of the irradiated object. At the same time, a double-sided irradiation can provide high X-ray beam efficiency at dose uniformity ration (DUR) <1.5 for sizeable object thickness. At four-sided irradiation, the angular orientation of electron beam incidence on the X-ray converter should be changed so as to focus the electrons to the center of the converter. At this mode X-ray beam efficiency is more than 60%.     

X-射线荧光光谱分析技术的发展

归纳了X-射线荧光光谱分析技术发展的进程。从现代控制技术的改善、仪器检测性能的提高、元素检测范围的扩大等8方面阐述了波长色散X-射线荧光光谱技术的进展,还就能量色散X-射线荧光光谱仪的X射线管和探测器技术的快速发展及近10年来我国在X-射线荧光光谱分析方法方面的论文发表情况进行了总结,对近年来X-射线荧光光谱仪的发展趋势———手持式、偏振、微束分析等进行了评述,并对其技术的发展方向进行了展望。     

The birth of the X-ray refractive lens

In the X-ray region, no optics based on the principle of refraction existed since the discovery of the X-rays by Röentgen in November 1985, although mirrors and zone-plates that use the principle of reflection and diffraction have been employed. The idea of a practical X-ray refractive lens was first disclosed in February 1994, i.e., just one year before the centenary of the discovery of X-rays. The present paper reviews why the X-ray lens did not appear for so many years, and how the design was born. The paper also discusses technologies to be developed for high performance X-ray lenses, and advantages of refractive X-ray lenses over other X-ray optics.     

Application of large-area avalanche photodiodes to X-ray spectrometry of muonic atoms

Large-area avalanche photodiodes have been investigated as 1.9-keV X-ray detectors for the muonic hydrogen Lamb-shift experiment. We report experimental tests carried out for evaluation of the avalanche photodiode capabilities for X-ray detection in the intense radiation and low counting rate environment of experiments with muonic atoms. Several muonic atoms were used and it was shown that the electronic background of muonic atom X-ray spectra can be reduced simply by timing the X-ray signal against the gate signal produced by the muon entrance. Furthermore, the background can be eliminated using coincidences between the X-ray signal and the signal resulting from the electron due to the muon decay. This coincidence discrimination results, however, in a reduction of the X-ray detection efficiency.     

Determination of X-ray compression efficiency of a thin film X-ray waveguide structure using marker layer fluorescence

We demonstrate that a thin marker layer, sandwiched in the guiding medium of a thin film planner X-ray waveguide structure, can be used to determine X-ray compression efficiency for a particular excitation mode. It can also be used in evaluating the transmission efficiency of waveguide structure and for the determination of X-ray intensities reaching the waveguide exit. This approach has been applied for determining X-ray compression and transmission efficiency of a Mo/B₄C/Mo based X-ray waveguide structure, by inserting a thin Fe marker layer.     

Analysis of field of view limited by a multi-line X-ray source and its improvement for grating interferometry

X-ray phase-contrast imaging based on grating interferometry is a technique with the potential to provide absorption, differential phase contrast, and dark-field signals simultaneously. The multi-line X-ray source used recently in grating interferometry has the advantage of high-energy X-rays for imaging of thick samples for most clinical and industrial investigations. However, it has a drawback of limited field of view (FOV), because of the axial extension of the X-ray emission area. In this paper, we analyze the effects of axial extension of the multi-line X-ray source on the FOV and its improvement in terms of Fresnel diffraction theory. Computer simulation results show that the FOV limitation can be overcome by use of an alternative X-ray tube with a specially designed multi-step anode. The FOV of this newly designed X-ray source can be approximately four times larger than that of the multi-line X-ray source in the same emission area. This might be beneficial for the applications of X-ray phase contrast imaging in materials science, biology, medicine, and industry.     

X-ray dosimetry using a charge injection type condenser

An X-ray dosimeter has been investigated with the use of a charge injection type condenser. The detector is small size and is housed in an epoxy resin approximately 4.5 X 2.5 X 1.5 mm. The X-ray dose can be determined by decreasing the amount of electron injected into floating gate through X-ray irradiation. The X-ray irradiation dose can be measured by decreasing of the capacitance. This dosimeter shows good linearity but the X-ray energy response for low energy region is higher than high energy region.     

Energy dispersive transmission X-ray scanning micro-imaging with an X-ray guide tube

A scanning micro-imaging instrument using an energy dispersive transmission X-ray spectrometry is developed. This instrument consists of micro X-ray source, X-ray guide tube, x–y scanning stage, and an SDD (Silicon Drift Detector), which is an energy dispersive X-ray spectrometer with a high throughput signal processor for measuring transmission X-ray spectrum. Using this instrument, (1) two-dimensional imaging of an intermediate product of multi-layer ceramic capacitor, and (2) thickness distribution imaging of an aluminum can-tab top, are performed nondestructively.     

X射线晶体学在高等教育中的通识性

X射线晶体学是一门研究物质晶体结构的科学,X射线衍射技术已成为当今化学、材料、生命等众多科学领域中对物质结构研究的必要手段与方法。本文从X射线晶体学的诞生、发展和迅速普及的角度,谈谈X射线晶体学的发展历程对人类文明的贡献,以及X射线晶体学在当今高等教育中的重要性,从而阐述在高等学校通识教育中加强与推广X射线晶体学的必要性与可行性。     

Radiative auger effect and extended X-ray emission fine structure (EXEFS).

Radiative Auger spectra are weak X-ray emission spectra near the characteristic X-ray lines. Radiative Auger process is an intrinsic energy-loss process in an atom when a characteristic X-ray photon is emitted, due to an atomic many-body effect. The energy loss spectra correspond to the unoccupied conduction band structure of materials. Therefore the radiative Auger effect is an alternative tool to the X-ray absorption spectroscopy such as EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure), and thus it is named EXEFS (Extended X-ray Emission Fine Structure). By the use of a commercially available X-ray fluorescence spectrometer or an electron probe microanalyzer (EPMA), which are frequently used in materials industries, we can obtain an EXEFS spectrum within 20 min. The radiative Auger effect, as an example, demonstrates that the study on atomic many-body effects has become a powerful tool for crystal and electronic structure characterizations. The EXEFS method has already been used in many industries in Japan. Reviews about the applications and basic study results on the radiative Auger effect are reported in this paper.     

Nanosized Vanadium Diboride: Synthesis,Structure, and Properties

Russian Journal of General Chemistry - X-ray diffraction, scanning electron microscopic, and X-ray photoelectron spectroscopic examinations, as well as energy dispersive X-ray and elemental...