Progress in science and technology on photostimulable BaFX:Eu (X=Cl, Br, I) and imaging plates

Imaging plate (IP) is a two-dimensional detector of ionizing radiation utilizing photostimulable BaFX:Eu²⁺ (X=Cl, Br, I). First type was developed about 20 years ago. As for the mechanism of the photostimulated luminescence (PSL), a lot of arguments have been done after the presentation of the first model by Takahashi et al. In principle, the model is supported by the recent papers.

In the meantime, the performance of IPs is drastically improved. Then, the computed radiography and the radioluminography (RLG) systems, which take advantage of the excellent feature in linearity and high sensitivity of IPs, were developed that became an inevitable equipment for medical diagnostics and scientific research. The late Professor Shigeo Shionoya greatly contributed to analysis of the PSL mechanism and development of the RLG technology.     

Methodological challenges of optical tweezers‐based X‐ray fluorescence imaging of biological model organisms at synchrotron facilities

Recently, a radically new synchrotron radiation‐based elemental imaging approach for the analysis of biological model organisms and single cells in their natural in vivo state was introduced. The methodology combines optical tweezers (OT) technology for non‐contact laser‐based sample manipulation with synchrotron radiation confocal X‐ray fluorescence (XRF) microimaging for the first time at ESRF‐ID13. The optical manipulation possibilities and limitations of biological model organisms, the OT setup developments for XRF imaging and the confocal XRF‐related challenges are reported. In general, the applicability of the OT‐based setup is extended with the aim of introducing the OT XRF methodology in all research fields where highly sensitive in vivo multi‐elemental analysis is of relevance at the (sub)micrometre spatial resolution level.     

Depth‐selective elemental imaging of microSD card by confocal micro XRF analysis

A semiconductor device, a microSD card, was measured by using two XRF instruments. 2D elemental images were obtained using a micro‐XRF system with a spatial resolution of 10 µm. Elemental distributions of the near‐surface region of the sample were clearly shown. Titanium was observed in the resin constituting the sample. Nickel and gold were observed on a terminal and localization of the sample. Elemental distribution of copper reflected the circuit structure of the measurement area that was in the neighborhood of the sample surface. Moreover, the elemental depth distributions of the sample were measured by using a confocal micro‐XRF instrument. The confocal micro‐XRF instrument was constructed in the laboratory with fine‐focus polycapillary x‐ray optics. The depth resolution of the developed spectrometer was 13.7 µm at an energy of Au Lβ (11.4 keV). The elemental images obtained at near‐surface by confocal micro‐XRF were the same as the results obtained from 2D micro‐XRF. However, different Cu images were obtained at a depth of several tens of micrometers. This indicates that microSD cards consist of a few different Cu‐circuit structure designs. The elemental depth distributions of each circuit structure of the semiconductor device were clearly shown by confocal micro‐XRF. Copyright © 2013 John Wiley & Sons, Ltd.     

成像板伽马图像测量研究

研究了成像板辐射图像测量的基本原理及其物理机制,并将其应用于伽马图像测量。建立了MS,SR和TR三种类型成像板数值模拟模型,分别使用MCNPX程序和基于Geant4开发的NPE程序计算了三种成像板对不同能量伽马射线的能量沉积,计算结果表明:SR和MS成像板比TR成像板能量沉积在低能部分大3~5倍,高能部分大7~9倍。实验测量了MS成像板灵敏度随铜膜厚度的变化关系,测量结果与理论计算结果有较好的一致性。理论与实验结果表明:成像板伽马图像测量的空间分辨力优于50 m。     

Application of multivariate statistical methods to classify archaeological pottery from Tel‐Alramad site,Syria, based on x‐ray fluorescence analysis

Radioisotope x‐ray fluorescence (XRF) analysis has been utilized to determine the elemental composition of 55 archaeological pottery samples by the determination of 17 chemical elements. Fifty‐four of them came from the Tel‐Alramad site in Katana town, near Damascus city, Syria, and one sample came from Brazil. The XRF results have been processed using two multivariate statistical methods, cluster and factor analysis, in order to determine similarities and correlation between the selected samples based on their elemental composition. The methodology successfully separates the samples where four distinct chemical groups were identified. Copyright © 2006 John Wiley & Sons, Ltd.     

Non‐destructive characterization of 17th century painted silk banner by the combined use of Raman and XRF portable systems

X‐ray fluorescence spectroscopy (XRF) and Raman spectroscopy analysis were performed to examine a 17th century painted silk banner in order to characterize the pigments and materials used. This complementary approach yields information on the elemental (XRF) and on the molecular composition (Raman) of the used compounds. The paint layer, ground layer under gilding, and gilding layer were investigated. For the studied object, vermilion (HgS), lead white (2PbCO₃ · Pb(OH)₂), red lead (Pb₃O₄), and aurichalcite ((Cu,Zn)₅(CO₃)₂(OH)₆) were found. The presence of silver and gold foils was confirmed. The techniques used in the analysis were portable, non‐destructive, and non‐invasive, which is very desirable when analyzing cultural heritage objects. The obtained results were used by the conservators to develop a showcase prototype for safe exhibition. Copyright © 2015 John Wiley & Sons, Ltd.     

Monte Carlo simulation code for confocal 3D micro‐beam X‐ray fluorescence analysis of stratified materials

Stratified materials are of great importance for many branches of modern industry, e.g. electronics or optics and for biomedical applications. Examination of chemical composition of individual layers and determination of their thickness helps to get information on their properties and function. A confocal 3D micro X‐ray fluorescence (3D µXRF) spectroscopy is an analytical method giving the possibility to investigate 3D distribution of chemical elements in a sample with spatial resolution in the micrometer regime in a non‐destructive way. Thin foils of Ti, Cu and Au, a bulk sample of Cu and a three‐layered sandwich sample, made of two thin Fe/Ni alloy foils, separated by polypropylene, were used as test samples. A Monte Carlo (MC) simulation code for the determination of elemental concentrations and thickness of individual layers in stratified materials with the use of confocal 3D µXRF spectroscopy was developed. The X‐ray intensity profiles versus the depth below surface, obtained from 3D µXRF experiments, MC simulation and an analytical approach were compared. Correlation coefficients between experimental versus simulated, and experimental versus analytical model X‐ray profiles were calculated. The correlation coefficients were comparable for both methods and exceeded 99%. The experimental X‐ray intensity profiles were deconvoluted with iterative MC simulation and by using analytical expression. The MC method produced slightly more accurate elemental concentrations and thickness of successive layers as compared to the results of the analytical approach. This MC code is a robust tool for simulation of scanning confocal 3D µXRF experiments on stratified materials and for quantitative interpretation of experimental results. Copyright © 2011 John Wiley & Sons, Ltd.     

庙底沟遗址出土仰韶文化彩陶的科学研究

彩陶文化作为新石器时期的重大发明,改变了远古先民的审美方式,而著名的仰韶文化以其彩陶的优美造型、绚丽色彩和丰富的纹饰揭示了原始的艺术特征,承载了史前时期重要的社会文化信息。而利用现代光谱分析技术准确、无损和微损的特点,可以为文物保护的研究提供更科学的技术支撑。研究应用相位辅助光学三维扫描、多光谱成像、X射线荧光、激光拉曼光谱分析技术,对河南省陕县庙底沟遗址出土的新石器时代晚期仰韶文化彩陶碗进行面、点相结合的综合分析,获得了较为完整的文物物理和化学信息。利用三维扫描技术所构建的彩陶碗数字化模型对样品进行了几何尺寸的非接触测量和虚拟修复,利用多光谱成像技术所获得的灰度图像对样品表面化学特征相似区域进行了区分,结合X射线荧光和激光拉曼光谱分析技术对彩陶残片的分析结果,确定了所分析彩陶样品的主要化学成分特征和颜料物相组成。综合研究结果,提出了建立彩陶文物多源信息数字化模型的构想,为这类文物的数字化保护和展示提供了基础科学信息。     

Objective Stenosis Quantification From Post-Stenotic Signal Loss in Phase-Contrast Magnetic Resonance Angiographic Datasets of Flow Phantoms and Renal Arteries

In this study a semi-automated and observer-independent algorithm for quantifying post-stenotic signal loss (PSL) in three-dimensional phase-contrast (PC) magnetic resonance angiography (MRA) of patients with renal artery stenosis is presented. This algorithm was developed on MRA datasets of stenotic phantoms, included in a flow circuit with stationary flows. The length and the severity of the PSL (incorporating both the length and the degree of PSL) in the MRA datasets were proposed for quantifying the stenoses. The algorithm was tested in renal arteries; ten patients with renal artery stenosis and seven healthy volunteers were investigated. Digital subtraction angiography was performed in the patients and served as the gold standard. Stenosis severity showed better correlation with the severity of the PSL than with the length, both for in vitro and in vivo measurements. Spearman correlation coefficients (r_s) showed statistically significant correlations between the severity of the PSL and parameters determined by digital subtraction angiography, i.e., percent diameter stenosis (r_s = 0.90). The length of the PSL showed no correlation with the diameter stenosis (r_s = 0.37). In conclusion, this study presents a semi-automated and observer-independent way of quantifying signal loss, and the severity of the PSL is proposed for quantifying stenoses, rather than the length of PSL.     

河南省清凉寺窑址出土富铁釉瓷的无损分析研究

富铁釉瓷在中国古陶瓷史上具有重要地位，综合利用光学相干层析成像技术(OCT)、光学显微镜(OM)、激光拉曼光谱技术(LRS)和X射线荧光光谱分析技术(XRF) 对河南省宝丰清凉寺窑址出土宋金时期富铁釉瓷样品进行无损分析研究，获取了富铁釉瓷的釉层结构、釉面析晶的物相信息及胎釉化学成分等信息，探讨了釉层断面OCT灰度图像特征与其显微结构之间的关系以及富铁釉瓷的烧制工艺。结果表明，酱釉瓷和柿叶红釉瓷表面及黑釉红斑区存在富铁析晶层，黑釉瓷釉层表面未发现富铁析晶层的存在。酱釉瓷釉层富铁析晶层中铁的氧化物以ε-Fe₂O₃晶体为主，而柿叶红釉层则主要是α-Fe₂O₃晶体，黑釉红斑层同时存在ε-Fe₂O₃，α-Fe₂O₃晶体以及磁铁矿。上述差异形成的原因与釉层化学成和烧制工艺存在联系。釉层中高含量碱土金属氧化物及氧化铁区域更容易析出氧化铁晶体。黑釉瓷烧成气氛以还原气氛为主，而酱釉瓷和柿叶红釉瓷则倾向于氧化烧成气氛，且柿叶红釉瓷的烧成温度高于酱釉瓷。该研究将OCT，OM，LRS与XRF相结合，有助于加强对富铁釉瓷的整体认知，为富铁釉瓷的断源断代提供更为丰富的线索。     

A sample carrier for measuring discrete powdered samples with an ITRAX XRF core scanner

The elemental composition of discrete powdered sediment samples can be measured by the energy‐dispersive X‐ray fluorescence (XRF) system that is installed in XRF core scanners. Because an appropriate sample carrier for powdered samples is currently not available, for example, for the ITRAX XRF core scanner, such a carrier is presented in this technical note. The designed sample carrier can hold 30 sample cups with a volume of 0.88 cm³ each. A maximum of 5 sample carriers, that is, 150 samples, can be measured in one run. The sample cups and carriers are optimized for a measurement procedure with a step size of 5 mm and variable count times up to 100 s per sample. With this setting, data are collected from an area of 100 mm² in the center of the sample thereby ensuring a good representativeness of the signal because potential sample inhomogeneity is accounted for. Because the described sample carrier system allows rapid element analyses of discrete powdered environmental samples with an XRF core scanner, it may in some cases represent a time‐ and cost‐efficient alternative to conventional XRF analyses.     

不同处理工艺钢渣的X射线衍射和X射线荧光光谱分析及其活性指数预测模型

以不同处理工艺钢渣,即转炉热泼渣、转炉滚筒渣、铸余渣、铁水脱硫渣、电炉热泼渣和电炉滚筒渣作为研究对象。利用X射线衍射仪和X射线荧光光谱分析仪研究钢渣的化学成分与物相组成。利用BP神经网络模型建立钢渣活性指数预测模型,研究化学成分、物相组成与活性的关系。结果表明： 钢渣的处理工艺不同,其化学成分与物相组成存在明显差异;钢渣活性指数预测模型具有良好的符合性,即相对误差为2.42%和-2.54%,能充分反映输入层与输出层之间的映射关系。     

Confocal macro X‐ray fluorescence spectrometer on commercial 3D printer

Novel confocal X‐ray fluorescence (XRF) spectrometer was designed and constructed for 3D analysis of elementary composition in the surface layer of spatially extended objects having unlimited chemical composition and geometrical shape. The main elements of the XRF device were mounted on a moving frame of a commercial 3D printer. The XRF unit consists of a silicon drift detector and a low‐power transmission‐type X‐ray tube. Both the excitation and secondary X‐ray beams were formed and regulated by simple collimator systems in order to create a macro confocal measuring setup. The spatial accuracy of the mechanical stages of the 3D printer achieved was less than 5 μm at 100‐μm step‐size. The diameter of the focal spot of the confocal measuring arrangement was between 1.5 and 2.0 mm. The alignment of the excitation and secondary X‐ray beams and the selection of the measuring spot on the sample surface were ensured by two laser beams and a digital microscope for visualization of the irradiated spot. The elements of the optical system together with the XRF spectrometer were mounted on the horizontal arm of the 3D printer, which mechanical design is capable of synchronized moving the full spectroscopic device within vertical directions. Analytical capability and the 3D spatial resolution of the confocal spectrometer were determined. Copyright © 2017 John Wiley & Sons, Ltd.     

Quantitative elemental analysis of individual particles with the use of micro‐beam X‐ray fluorescence method and Monte Carlo simulation

The aim of the work was to develop a Monte Carlo (MC) method and combine it with micro‐beam X‐ray fluorescence (XRF) technique for determination of chemical composition of individual particles. A collection of glass micro‐spheres, made of NIST (National Institute of Standards and Technoly) K3089 material of known chemical composition, with diameters in the range of 25–45 µm was investigated. The micro‐spheres were measured in a scanning micro‐beam XRF spectrometer utilising X‐ray tube as a source of primary radiation. Results obtained for low Z elements showed high dependence on particle size. It was found that the root mean square of concentration uncertainty, for the all elements present in the particle, increases with growing sample size. More accurate results were obtained for high Z elements such as Fe–Pb, as compared to others. The elemental percentage uncertainty did not exceed 14% for any particular sample and 6% for the whole group of the measured micro‐spheres as an average. Results obtained by the Monte Carlo method were compared with other analytical approaches. Copyright © 2009 John Wiley & Sons, Ltd.     

利用毛细管X光透镜共聚焦微束X射线荧光技术对单根头发中元素空间分布进行无损扫描分析

头发中的元素与人的饮食和健康状况有关,对头发中元素的分析,不仅可用于刑事物证鉴别,还可为疾病的预防和治疗提供依据,因此,如何检测头发中元素分布等信息倍受人们关注。本文利用基于毛细管X光透镜和实验室普通X射线光源的共聚焦微束X射线荧光技术对单根头进行了无损扫描分析,分析了单根头发中元素的空间分布。在该毛细管X光透镜共聚焦微束X射线荧光技术中,毛细管X光会聚透镜的出口焦斑和毛细管X光平行束透镜的入口焦斑处在共聚焦状态,从而形成共聚焦微元,探测器只能探测到来自该共聚焦微元中的X射线信号,降低了背底信号对X射线荧光谱的影响,从而有利于提高该共聚焦X射线荧光技术的分析精度。该共聚焦技术中采用了具有高功率密度增益的毛细管X光会聚透镜,降低了该共聚焦X射线荧光技术对X射线光源功率的要求,从而保证了该共聚焦技术可以采用实验室普通X射线光源,降低了实验成本。实验表明,毛细管X光透镜共聚焦微束X射线荧光技术在单根头发元素分布检测中具有应用价值。     

多孔硅的电荷存贮现象

Uhlir[1]和Tunner[2]发现多孔硅(PS)以来,对其形成机制,电化学特性等进行了深入细致的研究.特别是近年Canham[3]观察到PS的可见光致发光现象后,PS的光电特性成为人们研究的焦点.在我们的研究中,首次观察到PS具有存贮电荷的能力.     

Thickness determination of gold layer on pre‐Columbian objects and a gilding frame,combining pXRF and PLS regression

In conservation, restoration and characterization studies of art and archaeological objects, the improvement of analytical techniques is a tendency. X‐ray fluorescence (XRF) is a versatile technique, and it has been widely used in the last decades for characterization of a great variety of materials (metals, glass, paints, inks, ceramics, etc.) applied to cultural heritage studies. Besides the chemical composition, it is possible to infer the layer thickness through XRF, enabling a general knowledge of the manufacturing techniques implemented by the culture of origin, as well as the association with the technological level reached for the production of each kind of artefact. The aim of this study is to introduce an alternative way for gold thickness determination of coatings in cultural heritage objects, combining portable XRF data and partial least square regression. As a case of study, we present the use of this methodology in portable XRF measurements performed in situ on a gilding frame in Brazil and in two pre‐Columbian artefacts from Chavin culture in Peru. Gold layers with thicknesses determined by Rutherford backscattering spectrometry (RBS) were used as standards to perform a calibration model and to check the methodology before its application to unknown artefacts. Copyright © 2016 John Wiley & Sons, Ltd.     

Preparation of sulfur reference materials that reproduce atmospheric particulate matter sample characteristics for XRF calibration

Energy‐dispersive X‐ray fluorescence (XRF) is an important tool used in routine elemental analysis of atmospheric particulate matter (PM) samples collected on polytetrafluoroethylene (PTFE) membrane filters. The method requires calibration against thin‐film standards of known elemental masses commonly obtained from commercial suppliers. These standards serve as a convenient and widely accepted interlaboratory reference but can differ significantly from samples in their chemical composition, substrate, and geometry. These differences can introduce uncertainties regarding the absolute accuracy of the calibration for atmospheric samples. Continuous elemental records of the US Interagency Monitoring of Protected Visual Environments (IMPROVE) PM monitoring network extend back to 1988. Evaluation of long‐term concentration trends and comparison with other networks demand a calibration that is accurate and precise compared with the uncertainty of the XRF measurement itself. We describe a method to prepare sulfur reference materials that are optimized for calibration of XRF instruments used to analyze IMPROVE PM samples. The reference materials are prepared by using the atmospheric form of the element, by reproducing the sample geometry, and by using the same substrate as in samples. Our results show that stable, pure, anhydrous, and stoichiometric deposits are collected onto the filter substrates, and furthermore, that the reference material masses are accurate and have acceptable uncertainty in the measurement range. The XRF response of the sulfur reference materials is similar to other commercial standards and is linear in the measurement range, and the slope of the multipoint calibration curve has very low uncertainty. These reference materials are valid for the calibration of XRF systems, and they bring improved transparency and credibility to the IMPROVE calibration. Copyright © 2013 John Wiley & Sons, Ltd.     

Assessment of teeth elemental content using μ‐EDXRF: effects by in‐office and at‐home bleaching products

The purpose of this in vitro study is to assess whether the elemental content of tooth enamel is altered when bleaching the teeth with bleaching gel. Because of tooth bleaching growing popularity and to match the public demands, manufacturers increased the range of bleaching products available, changing its presentation, techniques and concentration of active principles. This way, two different bleaching products were compared, one for in‐office and another for domestic use. In order to perform this evaluation, sound vestibular surfaces of anterior healthy teeth, extracted for periodontal or orthodontic reasons, were treated with the bleaching products accordingly to manufacturer instructions. Spectra were acquired using the M4 Tornado μ‐XRF setup, and quantitative calculations were performed using fundamental parameter method to determine the elemental composition of the analyzed samples before and after treatment. No significant statistical differences in the mineral content of the analyzed teeth were obtained. Copyright © 2014 John Wiley & Sons, Ltd.     

Deconvolution of distinct lithology chemistry through oversampling with the Mars Science Laboratory Alpha Particle X‐Ray Spectrometer

The Alpha Particle X‐Ray Spectrometer (APXS) determines the chemical composition of Martian rocks and soils on‐board both active National Aeronautics and Space Administration (NASA) rovers using X‐ray emission spectroscopy through complementary particle‐induced X‐ray emission (PIXE) and X‐ray fluorescence (XRF) excitation methods. A single APXS spectrum represents the sum of the signals from within the instrument's field of view (FOV). In the past, features smaller than the FOV have been investigated through repeated measurements with stepwise lateral offsets. These lateral offsets allow for empirically extracting, through elemental correlations, distinct compositions of different features. Here, we present a novel analytical method for deconvolving the endmember chemistry of visually distinct components through oversampling and the integrated analysis of the elemental data and supporting images. We discuss specifically the method's application to three targets investigated by the Mars Science Laboratory rover Curiosity during its traverse, as well as the added information that can be gained from this method in the future. Copyright © 2016 John Wiley & Sons, Ltd.