深海富钴结核微区X射线荧光光谱分析和数据挖掘

西太平洋富钴结核是近年来新发现的海底固体矿产资源,富含Mn,Fe,Co,Ni和Cu等多种关键金属元素。富钴结核是一种非均质的地球化学和矿物学集合体,粒径约6 cm的结核在生长过程中记录了数千万年的海洋沉积历史,亟需高分辨率的分析技术揭示古海洋环境信息。采用微区X射线荧光光谱仪（μ-XRF）,对C3BC1704富钴结核开展多元素面扫描,获得了原位高分辨率多元素的信号强度数据,评价了μ-XRF技术在富钴结核中的应用质量。元素信号谱峰特征和数据频谱分布结果显示,富钴结核中Mn,Fe,Ti,Co,Ca和Ni等元素信号强度敏感,数据呈现相对较好的正态分布特征,可用于定量或半定量分析;Si,Cu和Al等元素信号较弱,数据呈现左偏的正态分布特征,建议相关数据仅作参考。μ-XRF获得的数据量庞大且彼此独立,本研究将不同元素连接成彼此关联的多维矩阵,实现了数据的位置信息和特征元素之间的数学运算和筛选,了解了金属元素的分布和变化特征,揭示了富钴结核生长过程的环境变化。结果显示,Mn和Fe等元素在生长层中波动剧烈,金属元素在富钴结核中的分布极不均匀,显示出多成因类型的交替微层和7个大的生长周期旋回。C3BC1704富钴结核主体暴露在海水中,金属元素主要来自海水,化学组成指示为典型的水成成因。进一步定量分析结果显示,Mn,Cu和Ni等元素含量从内部向外围呈现同步降低的趋势,Fe,Ti和Co等元素含量则呈现同步升高的趋势,这些特征指示早期偏向于成岩富集环境,晚期则以水成富集为主。富钴结核金属元素的分布和变化特征,清晰呈现了富钴结核的生长结构,揭示了富钴结核生长过程的环境变化,有利于富钴结核的成矿模型的构建。     

核子微探针技术的发展及其应用研究

核子微探针的发展提供了一种在微米尺度内分析微量元素的强有力的工具,用它研究海洋矿物已成为一项热门的课题．因为象海洋锰结核和海山锰结壳这种海洋矿物的生长速率很慢,一百万年只长几毫米,用核子微探针能够直接地、仔细地观察这些矿物缓慢的生长过程．核子激探针能够测量单个细胞中微量元素的成分和分布,以及它们对生物的作用．它还能研究在球墨铸铁中微量元素的含量,以及它们对球化过程的影响．目前,ＳＩＮＲ核子微探针的空间分辨率是２ｍｍ,通过改进聚焦系统和扫描图像解卷积技术,分辨率将进一步提高．三维成像技术已经发展成一个重要分支,其中扫描透射显微技术（ＳＴＩＭ）是一个成功的例子．因为成像技术只需要非常小的束流强度,它有可能使核子微探针的分辨率达到纳米水平． The development of nuclear microprobe techniques provides a powerful means for micro-analysis in areas with micron scales. Great interest has been shown in the applications of the nuclear microprobe for investigating marine ores. Because the accumulations of marine ores, such as deep-sea ferromanganese nodules and seamount ferromanganese crusts,are very slow, about a few millimeters per million years, the ability of microscopic analysis of trace elements brings the nuclear microprobe...     

Calibration-Free Libs for Determination of the Mn/Fe Ratio in Ferromanganese Nodules with a Portable Diode-Pumped Solid-State Laser

Journal of Applied Spectroscopy - The Mn/Fe ratio, which serves as a marker of the contents of rare-earth and platinum-group elements in ferromanganese nodules, was determined in samples taken...     

X-Ray fluorescence analysis using synchrotron radiation of manganese minerals from marine and lake bottom sediments

We perform X-ray fluorescence analysis of ferromanganese crusts from regions of the Okhotsk and Bering Seas and the Lake Miassovo (Southern Urals) with different geological structures using synchrotron radiation combined with X-ray diffraction and infrared spectroscopy (SR XRF). The consistency of the minor element composition to the structural patterns of manganese minerals of investigated samples is demonstrated.     

Manganese/polymetallic nodules: Micro-structural characterization of exolithobiontic- and endolithobiontic microbial biofilms by scanning electron microscopy

Polymetallic/ferromanganese nodules (Mn-nodules) provide a rich source for manganese. It is not yet known if the nodules have a biogenic or an abiogenic origin. Here we applied the technique of high-resolution scanning electron microscopy, in combination with energy dispersive X-ray spectroscopical (EDX) analysis, to trace the existence of microbial biofilms. Two spatially separated assemblies exist, the exolithobiontic- and endolithobiontic colonizations. The exolithobiontic colonization is seen in the micro-canals, which traverse the outer surface layer of the nodules and are formed by elongated filamentous organisms, which show no signs of mineralization. In the center of the nodules three types of endolithobiontic microbial biofilms exist: first, cone-like microorganisms forming biofilms, second stone/pillar-like microorganisms and finally paving stone-like, hexagonal microorganisms. All are covered by brick-like mineral deposits. By EDX analysis we could measured the highest relative level of carbon (C) with respect to manganese (Mn) and sodium on the microorganisms. Our data are in perfect agreement with the assumption that the Mn deposits in the nodules are of biogenic origin. In a first approach, DNA from microorganisms from the interior of those Mn-nodules was isolated by PCR, and sequenced with respect to the 16S ribosomal RNA gene. Sequence comparison revealed that the sequence from the Mn-nodule, studied here, shares highest similarity to a bacterium living in soil, rich in iron and manganese. We propose that the microorganisms form a biofilm within the nodules onto which Mn is deposited due to an oxidation from Mn(II) to Mn(III)/Mn(IV).     

古尔班通古特沙漠生物土壤结皮反射光谱特征分析

通过对野外采样取得的新疆古尔班通古特沙漠中的生物土壤结皮、裸沙和干枯植被进行反射光谱测定,揭示出在干燥条件下各类地物的反射光谱特征。进一步对经过均匀喷洒0.5和1.0 mm水后的生物土壤结皮分别进行反射光谱测定,并对比分析了原始的和经水化实验后的生物土壤结皮光谱特征。依据生物土壤结皮的光谱特征,提出利用连续统去除技术估算生物土壤结皮覆盖度的方法,结果表明连续统去除光谱的负对数与生物土壤结皮盖度有很好的相关关系(r2=0.990 7)。     

Reverse Monte Carlo iterative algorithm for quantification of X-ray fluorescence analysis based on MCNP6 simulation code

Reverse Monte Carlo iterative algorithm has been developed for quantification of energy-dispersive X-ray fluorescence analysis in order to calculate the concentrations of the elementary composition in solid substances. The core of the simulation code was the MCNP6 that is a well-established and widely applied software package in the nuclear research and practice for simulation of nuclear systems or the full process of gamma- or X-ray spectrometry. The reverse Monte Carlo algorithm and the full analytical procedure was tested by quantitative XRF analysis of reference alloy samples. The atomic compositions of the reference samples were determined by reverse Monte Carlo technique and also fundamental parameter method and by spark emission atomic spectroscopy. The agreement between the results of these three analytical methods was found within the standard deviations of the major elements of the samples. The total duration of the reverse Monte Carlo numerical computation was minimized to a few minutes using the variance reduction procedures available in the MCNP6.     

Determination of the Mn/Fe Ratio in Ferromanganese Nodules Using Calibration-Free Laser-Induced Breakdown Spectroscopy

Optics and Spectroscopy - The Mn/Fe ratio in ferromanganese nodules is determined by calibration-free laser-induced breakdown spectroscopy based on the use of only the plasma temperature and...     

自由定标激光诱导击穿光谱技术在炉渣成分定量分析中的应用

采用自由定标激光诱导光谱技术(CF-LIBS)对炉渣中几种主要成分(CaO,SiO2,Al2O3,MgO)进行了定量分析.利用Nd:YAG激光脉冲在空气中烧蚀炉渣样品产生等离子体,等离子体光谱由中阶梯光栅光谱仪记录.通过几种主要元素的原子谱线和离子谱线的玻尔兹曼图,计算了等离子体的温度.利用Ca的一条谱线Stark展宽...     

EDXRF微量元素分析在文物断源断代中的研究

能量色散X荧光分析（EDXRF）是重要的元素成分析方法之一,现已成为一种强有力的定性和精确定量的无损分析测试技术。能量色散X荧光分析（EDXRF）技术具有不破坏分析样品,并能快速进行钠（Z11）至铀（Z92）的多元素的同时分析,以及分析的浓度范围宽广,精度高等特点,因此,特别适合于进行文物材料的成分分析研究,尤其适合测试极其珍贵的古陶瓷完整文物样品分析与鉴定。文章运用该方法对选自杭州南宋官窑窑址、龙泉古窑址出土的14个样品的南宋官窑青瓷、南宋龙泉窑青瓷和现代仿古青瓷等进行了元素分析的对比研究,分析测定古陶瓷样品中胎、釉的主、次量及微量元素组成,寻找组成中的“指纹”特征元素,试图为古陶瓷文物的断源、断代研究和真伪鉴定提供科学依据。研究结果表明能量色散X荧光分析（EDXRF）是一种较理想的文物研究和鉴定的科学分析手段。     

Extending the quantitative analytical capabilities of the EDXRF technique for plant‐based samples

The energy‐dispersive x‐ray fluorescence (EDXRF) technique has limitations in the quantitative analysis of light elements (low‐Z analytes with Z < 10), for many reasons. This work, however, circumvents the problem through an a priori determination of low‐Z analytes, representative of plant‐based samples. The main purpose of this work was to characterize the major elements in the dark matrix of some plant‐based samples (including biomonitors) using Rutherford backscattering spectrometry (RBS), and the results provided as a generalized input for EDXRF analysis. The derived stoichiometry and mass ratio for the moss, lichen, and cotton cellulose samples analyzed were found to be similar and close to C₇H₁₀O₅, with an average matrix of C = 49.8%, H = 4.0% and O = 45.8%. Quantitative analysis of plant‐based reference material IAEA‐336 (lichen) was subsequently carried out. Use of the a priori determined dark matrix elements (from one‐time RBS spectrometry) extended the scope of applicability of the EDXRF quantitative methods used, and improved accuracy in the elemental analysis of plant‐based samples. The results obtained were in good agreement with the reference values. Copyright © 2004 John Wiley & Sons, Ltd.     

节瘤缺陷激光损伤的研究进展

在近红外反射类激光薄膜中,节瘤缺陷是引起薄膜激光损伤的主要因素。为了提高激光薄膜的损伤阈值,对节瘤缺陷及其损伤特性进行研究具有重要意义。从真实节瘤缺陷和人工节瘤缺陷两个方面介绍节瘤缺陷的研究进展。基于真实节瘤缺陷的研究,建立了节瘤缺陷的结构特征,形成了节瘤缺陷损伤特性和损伤机制的初步认识,利用时域有限差分法(FDTD)模拟了电场增强,初步解释了节瘤缺陷的损伤机制,发明了抑制节瘤缺陷种子源的方法和激光预处理技术,减少了节瘤缺陷,提高了薄膜损伤阈值。但是真实节瘤缺陷的性质,如种子源尺寸、吸收性以及位置深度等,都难以控制和预测,难以开展节瘤缺陷损伤特性的系统和量化研究,致使关于节瘤缺陷损伤的科学认识尚有不足。基于人工节瘤缺陷的研究,可以实现节瘤缺陷损伤特性的系统、量化甚至单一因素研究,极大地提高了实验研究的效率和可靠性,获得了一系列定量损伤规律。人工节瘤缺陷的高度受控性使实验研究与理论模拟的可靠对比成为可能,人工节瘤缺陷的损伤形貌和FDTD电场模拟的直接比较实验不仅验证了时域有限差分法(FDTD)模拟电场的正确性,也进一步明确了电场增强是诱导节瘤缺陷损伤的主要机制。对节瘤缺陷的损伤机制有了更为深刻的认识后,人们开始调控节瘤缺陷的电场增强效应提高节瘤缺陷的损伤阈值,发展了宽角度反射薄膜技术和节瘤缺陷平坦化技术,抑制电场增强,提高损伤阈值。这扩展了控制节瘤缺陷的思路和方法,从原来单一的去除节瘤缺陷到调控节瘤缺陷,为进一步提高薄膜的损伤阈值开辟了新的方向和途径。     

基于激光诱导击穿光谱的合金钢组分偏最小二乘法定量分析

在炼钢中合金浓度的检测和控制对产品质量影响很大,激光诱导击穿光谱(laser induced breakdown spectroscopy, LIBS)技术具有快速、非接触、无需制样等特点,非常适合应用于合金成分的在线分析。但是由于合金中的C, S, P元素的成分含量都很低,其原子发射谱线极易淹没在复杂的铁元素特征谱线之中,造成这些重要元素在线定量分析困难。以合金钢标准光谱样品为研究对象,获取激光诱导击穿光谱数据,采用定标曲线法(calibration curve, CC)和偏最小二乘法(partial least squares, PLS),对合金钢样品的主量和微量元素进行定量分析。比较两种方法的定标结果得出：对于主量元素,PLS方法的定量分析水平优于传统的CC法;更重要的是对于微量元素,由于特征谱线极弱,CC法无法得出定量结果,而PLS法仍然具有良好的定量分析能力。同时,将PLS法回归模型特征谱线处的回归系数与原始有背景干扰的光谱强度数据进行比较,阐述了LIBS数据定量分析中PLS方法的优势。结果表明,在激光诱导击穿光谱合金成分分析中,PLS方法适合用于C等微量元素的定量分析。     

Rapid analysis of Na,Mg, Ca,Fe, and Zn in breakfast cereals (granola type) by energy dispersive-X-ray fluorescence

Energy dispersive-X-ray fluorescence (ED-XRF) is a well spread near-line analytical technique, suitable for easy and rapid measurement of major elements and/or trace elements especially in many different food matrices. This study demonstrates the fitness for purpose of this method to ensure the correct addition of minerals during breakfast cereal production. Indeed, variations in process and in raw material compositions may lead to values out of legal tolerance, and thus quality controls need to be regularly performed to meet the release compliance criteria. Using such analytical technique close to production lines can allow controls that are more systematic as well as avoiding the shipment of numerous samples for reference method analyses often done to external laboratories. Thus, ED-XRF allows to ensure finished products compliance with product declarations. A commercial ED-XRF device was used during this study. Within 7 min of analytical time for two replicates/sample, the developed method gave accurate results for the quantification of Na, Mg, Ca, Fe, and Zn in breakfast cereals without any proportional biases between ED-XRF and reference method (inductively coupled plasma-atomic emission spectrometry) results.     

Quantitative determination of mineral phase effects observed in APXS analyses of geochemical reference materials

Calibration of the Curiosity Rover's alpha particle X‐ray spectrometer (APXS) was accomplished using geochemical reference materials and a fundamental parameters treatment of the X‐ray fluorescence and particle‐induced X‐ray emission (PIXE) excitation processes. For most major and minor elements the influence of different rock types was not significant. For the three light elements, Na, Mg, and Al, which are excited almost entirely by PIXE, systematic differences among felsic and mafic rocks were observed. A qualitative explanation is found in the very shallow interrogation depth (a few microns), which suggests that the X‐rays of these elements must emerge from a single mineral rather than an assumed average over the various minerals present. A quantitative explanation was sought by determining the mineralogy of several reference materials and computing their expected PIXE X‐ray yields with an adaptation of the yield prediction sub‐routine GUYLS in the Guelph PIXE software package GUPIX. The complexity of assigning the certified overall element mass fractions to specific minerals limited this exercise to cases with only a few minerals present. Good agreement was found between the X‐ray yields determined in the calibration exercise and those predicted in this new approach. It is expected that automation of the computational approach may enable examination of mineralogically more complex reference materials. This might also offer a means of coupling results from the X‐ray diffraction and APXS instruments on Mars. Copyright © 2014 John Wiley & Sons, Ltd.     

表面电荷法平面元电荷系数的半解析解法

针对在线性及高次电荷估计下,表面电荷法中全解析法对平面元电荷系数求解和实现较复杂的问题,提出一种半解析法.将系数积分由局部坐标系变换到整体坐标系下分离参数的二重积分,利用内层积分存在解析解的特点,将二维问题降为一维,方便数值积分计算.对于对数奇异积分问题采用辅助函数法消除.通过算例与全解析法计算精度进行比较,结果表明,在一定的单元划分下,可达到很高精度,具有一定可行性.     

Geochemical study of black crusts as a diagnostic tool in cultural heritage

This contribution focuses on spectrometric analyses carried out on crust samples covering the stone surface of the boundary walls of the Tower of London. The main goal of this research is to investigate the degradation processes related to the environmental impact on cultural heritage. Specifically, the chemical contamination of stone substrate in the Tower of London due to the crust formation was examined through laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). This technique allowed us to achieve a complete characterization of the damage layers in terms of trace elements. In addition, optical microscopy (OM), scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS) and infrared spectroscopic techniques (FT-IR) were also used for an exhaustive characterization of the examined samples. Results obtained demonstrated that such a geochemical approach represents a powerful diagnostic tool in the study of black crusts, since it represents a reliable indicator of the environmental pollution. The higher concentrations of most heavy metals in black crusts with respect to the underlying stone suggest that crusts were greatly influenced by atmospheric inputs in their formation, mainly represented by mobile combustion sources. In addition, the possibility of analyzing in some samples the portion of altered substrate allowed us to hypothesize that some specific heavy metals tend to migrate from the crust to the unaltered substrate over time, becoming catalysts for the formation of new crust. Therefore, this research focuses on the role of diagnostics in order to plan suitable cleaning and consolidation intervention aimed at a better protection of the monument.     

Energy‐dispersive x‐ray fluorescence analysis of modern coloured glasses from Marinha Grande (Portugal)

The elemental composition (K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Sr, Ba, Nd and Pb) of modern coloured glasses was obtained by energy‐dispersive x‐ray fluorescence (EDXRF) spectrometry. This non‐destructive technique is frequently used in the analysis of historical glass objects. Two reference glasses were also measured to assess the overall accuracy of the EDXRF method. Reference and unknown glasses were analysed without any preparation. The coloured glass samples studied belong to the Glass Museum of Marinha Grande and were chosen from two distinct collections, which were characterized by the different concentrations of some elements (K, Ti, Cr, Mn, Fe, Ba and Pb). The determined major elements allowed the identification of two raw materials used in glass manufacture, sand and lime. Multivariate statistical analysis, namely principal component extraction, simplified the identification of some of the colouring chemical elements, associating them with the different colours of the glass objects. Copyright © 2003 John Wiley & Sons, Ltd.     

The validity of commercial LIBS for quantitative analysis of brass alloy — comparison of WDXRF and AAS

Commercial low-cost laser induced breakdown spectroscopy (LIBS) has been successfully employed for the quantitative analysis of a Cu-based alloy using a Nd:YAG laser at 1064 nm. The main aim of the present investigation is to explore the benefits of a commercial low-cost LIBS setup. It was recognized that some trace elements such as Al and S could not be detected by LIBS even with a high-resolution spectrometer. The main difficulties in quantifying Cu as a basic component of a brass alloy are related to the self-absorption of Cu spectral lines, with the effect complicated at Cu concentrations higher than 65%. However, few Cu lines such as that at 330.795 nm would be helpful to use due to their lower susceptibility to self-absorption. LIBS, flame atomic absorption spectrometry (FAAS), and wavelength dispersive X-ray fluorescence (WDXRF) were compared for the detection of major and trace metals in the Cu-based alloy. In the case of WDXRF, the brass samples were identified by using a standardless quantitative analysis program depending on a fundamental parameter approach. The quantitative analysis results were acceptable for most of the major and minor elements of the brass sample. Therefore, commercial low cost LIBS would be useful for quantitative analysis of most elements in different types of alloys.     

Quantitative major and trace elemental mapping by PIXE of concretionary pyrite from the Witwatersrand Basin,South Africa

Several concretionary pyrite grains displaying multiple, massive sulphide or silicate inclusion‐rich, annuli from two gold‐bearing reef horizons (Ventersdorp Contact Reef, Kimberley Reefs) in different parts of the Witwatersrand Basin were analysed by particle‐induced X‐ray emission (PIXE) and electron microprobe analysis (EMPA) for their major and trace element compositions. Both PIXE spot analysis and mapping of the distributions of major and trace elements were carried out, and EMPA was employed to obtain major element abundances for matrix corrections of PIXE analysis. Spatial analysis by PIXE is excellent in comparison with EMPA, as PIXE detection limits are lower by 1–2 orders of magnitude at comparable, short‐duration counting times (12 h for 4096 pixel analyses by PIXE). EMPA was successful in the identification of individual zones, for example on the basis of locally enriched minor elements Ni or As. This technique also provided essential standard‐based control on major element abundances for the standardless PIXE dynamic analysis. The compositional results obtained on concretionary pyrite grains by PIXE are distinctly different for each analysed grain, in terms of relative enrichment of certain minor and trace elements in specific zones. Gold was detected locally in the interiors of grains and/or along grain margins. The different results are discussed with regard to their possible meaning related to the origin of gold mineralization in the Witwatersrand ore deposit. Copyright © 2004 John Wiley & Sons, Ltd.