基于单毛细管椭球镜的微束X射线荧光成像

X射线荧光成像是一种可无损获得样品内部元素空间分布信息的实验技术,可分为荧光mapping扫描成像与荧光CT成像,其空间分辨率由X射线聚焦束斑的大小决定。上海光源成像线站已建立X射线荧光成像系统并对用户开放,在多个领域取得较好的研究成果,该系统基于狭缝限束获取微束X射线,束斑为150μm,限制了该方法的广泛应用。椭球聚焦镜是反射面为椭球面的单次反射单毛细管光学元件,基于全反射原理,具有反射效率高、工作距离长、接收角宽、适用X射线能量范围宽、体积小等优点,已应用到X射线聚焦、全场纳米成像等领域。由于对面型精度的要求较高,制备椭球聚焦镜难度较大。为满足广大用户对微束荧光成像的需求,自行设计并成功研制了针对微束荧光成像系统的单毛细管椭球镜,并对其进行了X射线聚焦性能检测,结果显示可获得14μm聚焦光斑,焦点处增益可达255倍。基于自主研制的椭球镜,在上海光源BL13W搭建微束X射线荧光成像系统,并开展了微束荧光mapping成像与微束荧光CT实验研究:(1)对中风鼠脑切片的荧光mapping扫描成像,得到中风鼠脑中微量元素铜、铁、钙与锌的元素分布荧光光谱图;(2)对鼠脑及毛细管中浓度为0.5 mg·L~(-1)的标准砷溶液进行同步辐射微束X射线荧光CT成像,利用OSEM重构算法重构投影数据,获得了鼠脑中铜元素和毛细管中砷元素二维分布的切片图。两组实验表明,基于自行设计与研制的单毛细管椭球镜的微束X射线荧光成像系统,样品处的光通量密度增加,空间分辨率得到提高,单张荧光光谱的获取时间显著减少,同时也提高了系统的元素探测限。     

同步辐射微束荧光CT及其应用新进展

同步辐射微束X射线荧光CT（SR-XFCMT）是将传统的X射线荧光分析法和计算机断层成像（CT）技术有机结合发展起来的一种先进的分析技术．SR-XFCMT可以给出元素在样品内部的分布而不需要对样品进行破坏性的处理，现已成为很多研究领域的有力工具．文章简要介绍了同步辐射微束荧光CT技术及其应用的最新进展，阐述了同步辐射微束X射线荧光CT的关键问题及其发展的前景.     

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。     

中国微束X射线荧光分析技术应用评介

简述了X射线荧光(XRF)分析与微束X射线荧光(MXRF)分析的技术特点、仪器构成、应用领域和工作范围。从准直的微束X射线荧光、整体X射线荧光与微束X射线荧光组合、波谱/能谱多功能组合和毛细管X光会聚透镜微束X射线荧光仪器四类仪器评介了中国微束X射线荧光仪器和分析技术的应用与发展。从分析功能定位和技术发展两方面,展望了微束X射线荧光技术的发展。提出将XRF分析中传统的微束原位(微区)XRF(MXRF)分析进一步区分为"微-纳区分析(μ/n-XRF)"和"微-毫区分析(μ/m-XRF)",如此区分该项技术及适用范围定位,对两者原位分析技术的发展都是有益的,特别也明确定位说明了整体/微区组合仪器的功能和适用范围发展与应用。作者强调:原位(微区)分析并非仅为单纯的分析工作,更重要的在于对被测样品特性的研究与结果解读!分析人员和专业科学家的密切合作,才能充分发挥原位微区分析技术的效能,充分解读展现分析结果的科学意义。     

毛细管X光透镜三维共聚焦微束X射线荧光技术在岩矿样品分析中的应用

利用毛细管X光透镜搭建了三维共聚焦微束X射线荧光谱仪,处在激发道的多毛细管X射线会聚透镜和处在探测道的多毛细管X射线平行束透镜处于共聚焦状态,该共聚焦结构降低了X射线荧光光谱的背底,从而有利于降低的X射线荧光分析技术的探测极限。在上述共聚焦结构中,多毛细管X射线会聚透镜和多毛细管X射线平行束透镜的焦斑重合形成共聚焦微元,探测器只能探测到来自该共聚焦微元内的X射线荧光信号,当该共聚焦微元在样品移动时,就可利用该共聚焦技术原位无损得到样品内部的三维X射线荧光信息。该共聚焦技术使用的多毛细管X射线会聚透镜具有103量级的功率放大倍数,从而降低了该共聚焦技术对高功率X射线源的依赖程度,即利用低功率普通X射线源就可以设计毛细管X光透镜共聚焦X射线荧光技术。利用上述共聚焦微束X射线荧光谱仪对两种岩矿样品进行三维无损分析,在其中一种岩石中发现：Fe浓度大的区域Cu的浓度也大,这在一定程度上反映了岩矿自然生长的机理。实验结果证明：该共聚焦X射线荧光技术可以在不破坏样品情况下分析岩矿样品中元素成分组成和元素三维分布情况。该共聚焦三维微束X射线荧光技术在矿石勘察、玉器选材和鉴别、石质食用器皿、“赌石”和家用石质地板检测等领域具有潜在的应用。     

微束X射线荧光分析

用能量色散微束X射线荧光分析仪实际测量了微束准直器孔径和X射线强度对微束空间分辨率的影响,在准直器孔径为0.1mm条件下,获得以FWHM定义的空间分辨率最好为0.073mm。通过微束扫描测量出某硫化锰矿微区内的Mn、Fe、Zn、Pb的三维等高线荧光强度分布图和不同小区域内的能谱。     

一种毛细管聚焦的微束X射线衍射仪

微区X射线衍射(micro-X-ray diffraction)分析在测量小样品或样品微区结构方面有着独特的优势.介绍了实验室自行研发的台式毛细管聚焦的微束X射线衍射仪(μ-Hawk),其主要由微焦斑X射线管、毛细管X光透镜、接收狭缝、SDD X射线探测器、q-q测角仪、三维样品台,以及在Lab VIEW语言环境下开发的计算机控制程序等部分组成.控制程序的主界面具备微区X射线衍射分析和微区能量色散X射线荧光分析两种分析模式.为了验证设备的可行性,分别对一枚人民币五角硬币上"角"字第一划中央处的微区和直径为140μm的铜质导线进行微区点分析;对苹果手机主板焊锡接触点上1.0 mm×0.6 mm区域内的物相分布进行二维扫描分析,具体方式为在二维待测区域内逐点自动执行q-q角度扫描,由程序控制的4个电机来实现此过程.分析结果表明,μ-Hawk所具备的微区能量色散X射线荧光分析模式,为物相结构的识别提供了元素种类的参考信息;与常规的X射线衍射仪相比较,μ-Hawk所采集的衍射图整体本底较低,并且所测得的衍射峰位置基本一致;μ-Hawk能适应小样品或样品微区物相结构的分析和物相分布的二维扫描分析,在材料科学、地球科学和文物保护等领域有着广泛的应用前景.     

实验室光源的微束X射线荧光成像系统研制及应用研究

微束X射线荧光成像(μ-XRFI)是无损获取样品内部元素微区分布信息的重要方法,主要应用于微米量级区域内的元素分辨成像。同步辐射是μ-XRFI的理想光源,由于其装置庞大、造价高昂,用户机时紧张,并不适宜于常规应用。基于实验室X射线光管、多毛细管聚焦镜、高精度样品台及硅漂移探测器,研制了一套具有元素分辨的μ-XRFI系统,性能测试结果表明该系统可以测量分析元素含量为0.001%量级的溶液样品和优于20μm的空间分辨能力。基于该μ-XRFI系统开展了应用研究,获得了小鼠脑、芯片及古代陶瓷样品中的多种主要元素及微量元素的空间分布,结果表明该系统可满足μ-XRFI的需求,可为生物医学、电子元件检测、瓷器色彩成分鉴定等领域研究提供帮助。     

整体毛细管X光透镜在大气颗粒物单颗粒分析中的应用

对大气颗粒物进行单颗粒X射线荧光(XRF)分析,是一种识别大气颗粒物来源的有力手段.为了利用实验室X射线光源对大气颗粒物进行单颗粒XRF分析,建立了基于整体毛细管X光透镜和实验室X射线光源的微束X射线谱仪.透镜焦斑处的功率密度增益在103数量级,焦斑直径为30 μm左右.该微束X射线谱仪对Fe-Kα线的最小探测极限为0.7 Pg.在Mo靶光源电压和电流分别为30 kV和50 mA的条件下,利用该谱仪对直径为9 μm的大气颗粒物单颗粒进行XRF分析时,测谱时间在180 s左右.实验表明,基于毛细管X光透镜和实验室X射线光源的微束X射线分析技术在大气颗粒物单颗粒分析中有着潜在的应用价值.     

采样间隔和投影数对SR-XFMT重构质量的影响

同步辐射微束X射线荧光CT(SR-XFMT)是一种能无损、高空间分辨和高灵敏地探测样品内部元素含量和分布的新技术. 对SR-XFMT实验进行了计算机模拟, 讨论了采样间隔和投影数对重构质量的影响, 分析发现采样间隔对重构质量的影响比投影数的影响要大.     

X射线荧光层析成像中消除散射光的方法

介绍了X射线荧光层析成像技术的成像原理及其在微量分析领域中的应用。针对X射线与物质相互作用时，不仅产生荧光，而且会产生各种散射光，为消除这些散射光对成像结果的影响，提出采用在与入射X射线垂直方向放置一个圆环状的晶体单色器，即双聚焦模式晶体单色器，使荧光与各种散射光分离，并聚焦在探测器上。这样不仅大大增强了荧光信号的强度，而且可使荧光探测器小型化。     

同步辐射X射线荧光光谱国内外研究进展

同步辐射光源是带电粒子在加速器储存环中以接近光速的速度运动时,沿轨道切线方向发射出的辐射,同步辐射X射线荧光分析(SR-XRF)是以同步辐射X射线作为激发光源的X荧光光谱分析技术.同步辐射X射线荧光分析包括了用于微区及微量元素分析的同步辐射XRF、用于表面及薄膜分析的同步辐射全反射X射线荧光(SR-TXRF)以及用于三...     

Some practical considerations about the effects of radiation damage on hydrated cells imaged by X-ray fluorescence microscopy

X-ray fluorescence (XRF) microscopy features unique capabilities which make it well suited for biological investigations. Its high sensitivity together with high spatial resolution and penetration depth provide a unique tool for trace elements analysis in heterogeneous samples. Like most of the X-ray based techniques, radiation damage sets hard limits on the ultimate performance. Although the interactions between matter and photons are well described from a physics point-of-view, there is a lack of experimental data, in particular for XRF imaging mode. In this context, this work proposes a practical approach in addressing the limits set by radiation damage to X-ray fluorescence imaging in the case of hydrated and unfixed cells at room temperature. We find that the maximum dose tolerated by ascidian blood cells is 10⁵ Gy. A simple theoretical model allowed the minimal doses required for a good image contrast to be determined for various experimental schemes. The results are consistent with the experimental observation on ascidian blood cells which exemplifies the peculiar case of highly concentrated samples (>10,000 ppm) at room temperature. The same simple model predicts that in the case of the detection of high Z trace elements in cryo-preserved cells, the relative detection limit set by radiation damage is below 0.1 ppm at a spatial resolution of 100 nm.     

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Ring coded imaging technology with high detection efficiency was put forward to diagnose space distribution for low intensity X-ray spot with several tens to hundred of keV. In this paper, the relations of detection efficiency and signal – noise ratio varied with the ring geometric parameters were researched. The coaxial imaging technology was resolved by employing the design of local micro joins on the ring aperture, and simulating the influence of micro joint area size on imaging quality. The ring aperture imaging system was developed and the Unique-II X-ray spot imaging experiment was implemented. The results show that the space distribution of the X-ray spot is approximate a ‘saddle’ shape, and the intensity in the middle part is lower than both sides along the long axis of the elliptical surface; this conclusion is consistent with pin-hole image; the detection efficiency of ring is evidently more than that of pin. Finally, the effects of and the R-L method and Wiener method used to restore the image are analyzed.     

硬X射线焦斑环孔编码成像的理论与实验研究

针对几十~百keV能量的低强度X射线焦斑源测量,建立了高探测效率环孔编码成像技术。研究给出了环孔成像效率和信噪比与环孔结构参数的关系,采用微联结的环孔结构设计并模拟了联结区尺寸对成像质量的影响,解决了环孔结构同轴成像技术难题。所建立环孔成像系统应用于Unique-II X射线焦斑源成像实验。结果表明,X射线焦斑的空间分布近似为‘马鞍’形状,而且中间部分的强度低于两侧的强度,与针孔成像结果相似,但环孔的探测效率明显高于针孔的效率。最后,分析了维纳滤波与R-L两种复原图像方法的效果。     

Critical issues in breast imaging by vibro-acoustography

Clinically, there are two important issues in breast imaging: detection of microcalcifications and identification of mass lesions. X-ray mammography is the main imaging method used for detection of microcalcification, and ultrasound imaging is normally used for detection of mass lesions in breast. Both these methods have limitations that reduce their clinical usefulness. For this reasons, alternative breast imaging modalities are being sought. vibro-acoustography is an imaging modality that has emerged in recent years. This method is based on low-frequency harmonic vibrations induced in the object by the radiation force of ultrasound. This paper describes potential applications of vibro-acoustography for breast imaging and addresses the critical imaging issues such as detection of microcalcifications and mass lesions in breast. Recently, we have developed a vibro-acoustography system for in vivo breast imaging and have tested it on a number of volunteers. Resulting images show soft tissue structures and calcifications within breast with high contrast, high resolution, and no speckles. The results have been verified using X-ray mammography. The encouraging results from in vitro and in vivo experiments suggest that further development of vibro-acoustography technology may lead to a new clinical tool that can be used to detect microcalcifications as well as mass lesions in breast.     

A sub‐micrometer resolution hard X‐ray microprobe system of BL8C at Pohang Light Source

A microprobe system has been installed on the nanoprobe/XAFS beamline (BL8C) at PLS‐II, South Korea. Owing to the reproducible switch of the gap of the in‐vacuum undulator (IVU), the intense and brilliant hard X‐ray beam of an IVU can be used in X‐ray fluorescence (XRF) and X‐ray absorption fine‐structure (XAFS) experiments. For high‐spatial‐resolution microprobe experiments a Kirkpatrick–Baez mirror system has been used to focus the millimeter‐sized X‐ray beam to a micrometer‐sized beam. The performance of this system was examined by a combination of micro‐XRF imaging and micro‐XAFS of a beetle wing. These results indicate that the microprobe system of the BL8C can be used to obtain the distributions of trace elements and chemical and structural information of complex materials.     

An integrated phase-resolved fluorescence imaging system with sub-nanosecond lifetime resolution

In this paper, a novel configuration of an integrated phase-resolved (PR) fingerprint fluorescence imaging system is proposed and implemented. In this integrated PR imaging system, a current modulated 402 nm dual diode laser is proposed to be the light source, to obtain both high laser power and easy modulability. To estimate the lifetime resolution of this PR imaging system, a novel method of using distance-selective suppression of fluorescence signals from two identical fluorescing samples is proposed. Detailed theoretical and experimental analyses are presented. The experimental results demonstrate that this integrated PR imaging system has a lifetime resolution of 0.1 ns. Fingerprint detection experiments are also carried out using this system with latent fingerprints deposited on substrates of aluminum foil and currency.     

同步辐射X射线荧光微探针技术测定熔融包裹体中的微量元素

采用同步辐射X射线荧光微探针无损分析技术,对吉林龙岗火山群地幔捕掳体中的斜方辉石矿物及其熔融包裹体进行了测试,并用美国玻璃标样(NIST 612)标定出K,Sc,Ti,Cr,Mn,Fe,Co,Ni,Cu,Zn,Ga,Sr,Y等13种元素的含量.其中,斜方辉石中的Cr?,Mn?,Fe?,Ni等元素含量与波长色散电子探针分析结果相对误差分别为15%,5%,7%,8%.包裹体中过渡族元素球粒陨石标准化曲线型式与中子活化全岩分析结果相似,反映原始岩浆在上升过程中经历了部分熔融或分离作用     

Characterization of solution-synthesized CdTe and HgTe

We report the characterization of solution-synthesized CdTe and HgTe nanocrystals by X-ray diffraction, transmission electron microscopy, and photoluminescence. Methanol solutions of sodium telluride and cadmium iodide or mercury iodide, respectively, are reacted to precipitate the nanocrystalline metal tellurides, while the sodium iodide byproduct remains in solution. The existence of crystalline CdTe, HgTe, and ternary HgCdTe compounds has been demonstrated by powder X-ray diffraction after a post-synthesis sintering process. Precipitated crystallites from this synthesis were analyzed by transmission electron microscopy, which revealed that crystal diameters can vary from approximately 1 nm to 100 nm and that crystals are stoichiometric within the detection limit of the electron microprobe technique. Narrow size ranges can be selected and investigated due to an in-situ separation process in the electron microscope. Photoluminescence is found at energies above the bulk exciton energy for CdTe and is attributed to near-band-gap recombination which is blue-shifted due to quantum confinement. Both low defect luminescence and dark field imaging suggest a high crystalline quality. A comparative characterization by photoluminescence, transmission electron microscopy, and X-ray diffraction evaluates the effects of heat treatments during and after synthesis.