Quantitative analysis by X-ray photoelectron spectroscopy without reference samples

A comparison between X-ray fluorescence analysis (XRFA) and X-ray photoelectron spectroscopy (XPS) indicates the applicability of these two methods as relative and absolute techniques. For XPS the absolute field of application should be preferred. An improvement of the Hirokawa-Ebel method (an absolute XPS analysis) is presented in this paper. It is shown that the knowledge of the inelastic mean free paths of the photoelectrons (IMFP) is no longer required, but the energy dependence of the IMFPs can be used as a basis. This guarantees simplicity and much more universal applicability.     

Quantitative multielemental analysis of titaniferous magnetites

Two representative titaniferous magnetite samples procured from Moulabhanj, Orissa, India have been studied by PIXE, EDXRF, Mössbauer spectroscopy, and XRD techniques. Major iron-bearing phases identified in the samples by Mössbauer spectroscopy and XRD are magnetite, hematite, ferrous ilmenite and ferric ilmenite. The Fe²⁺/Fe³⁺ ratio and the relative percentages of different minerals were determined from the resonance areas of Mössbauer spectra. Quantitative multielemental analysis was carried out by energy dispersive X-ray fluorescence (EDXRF) and proton induced X-ray emission (PIXE). Nineteen minor and trace elements have been quantified by EDXRF whereas by PIXE eighteen elements have been analyzed quantitatively. Concentrations of trace elements determined by EDXRF and PIXE were used in interpreting the physico-chemical condition of the depositional basin.     

Development of suitable plastic standards for X-ray fluorescence analysis

For the adoption of the EU directive “Restriction on use of certain Hazardous Substances” and “Waste Electrical and Electronic Equipment” using X-ray fluorescence analysis suitable standard materials are required.     

Application of X-ray photoelectron spectroscopy to quantitative analysis without standards

Summary The application of X-ray photoelectron spectroscopy to quantitative analysis without standards is discussed considering the mean free path of ejected electrons calculated by Lotz's equation or Powell's equation and the photoionization cross section calculated according to Scofield. The relative value of mean free path experimentally obtained and the difficulties of the preparation of standards are described with regard to various solid solution samples and oxide compounds.

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Anwendung der Röntgenphotoelektronen-Spektroskopie für die quantitative Analyse ohne Standards

Zusammenfassung Das Problem wird diskutiert unter Berücksichtigung der mittleren freien Weglänge der emittierten Elektronen gemäß den Gleichungen von Lotz und Powell, sowie dem Photoionisationsquerschnitt berechnet nach Scofield. Experimentell wurde der relative Wert für die mittlere freie Weglänge gefunden. Die Schwierigkeiten bei der Herstellung von Standards werden an Hand verschiedener fester Lösungen und Oxide beschrieben.

     

Quantitative electron-probe microanalysis without standards

Summary The dependence of the X-ray intensity emitted from the target on the take-off angle is applied to quantitative electron-probe micro-analysis without standards. The take-off angle is varied by rotating the inclined target.

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Quantitative Elektronenstrahl-Mikroanalyse ohne Standard

Zusammenfassung Die Abhängigkeit der Intensität der aus der Probe austretenden X-Strahlen von dem Abgangsfehlerwinkel dient zur quantitativen Elektronen-strahlmikroanalyse ohne Standard. Der Abgangsfehlerwinkel wird durch Drehen der schief gelagerten Probe verändert.

     

Quantitative modal determination of geological samples based on X-ray multielemental map acquisition.

Multielemental X-ray maps collected by a remote scanning system of the electron beam are processed by a dedicated software program performing accurate modal determination of geological samples. The classification of different mineral phases is based on elemental concentrations. The software program Petromod loads the maps into a database and computes a matrix consisting of numerical values proportional to the elemental concentrations. After an initial calibration, the program can perform the chemical composition calculated on the basis of a fixed number of oxygens for a selected area. In this way, it is possible to identify all the mineral phases occurring in the sample. Up to three elements can be selected to calculate the modal percentage of the identified mineral. An automated routine scans the whole set of maps and assigns each pixel that satisfies the imposed requirements to the selected phase. Repeating this procedure for every mineral phase occurring in the mapped area, a modal distribution of the rock-forming minerals can be performed. The final output consists of a digitized image, which can be further analyzed by common image analysis software, and a table containing the calculated modal percentages. The method is here applied to a volcanic and a metamorphic rock sample.     

Application of energy dispersive X-ray fluorescence spectrometry as multielemental analysis to determine the elemental composition of crumb rubber samples

The elemental content of different rubber samples was analyzed using different analytical methods (inductively coupled atomic emission spectroscopy and non-polarized energy dispersive X-ray fluorescent spectroscopy). A new application of energy dispersive X-ray spectrometry as an analytical method for the determination of elemental content of rubber samples was investigated. Control analyses were also carried out to compare the results by ICP-AES. In one hand four samples contained same quality of elements (Mg, Si, P, S, Ca, Fe, Zn), while another four samples were without phosphorous. On the other hand there were significant differences in the ratio of C/H in the case of each sample. Based on the results, it was concluded that the X-ray spectrometry as an analytical method is well-applicable to determine the elemental composition of rubber samples, but the calibration is a key part of the analysis. A good correlation was observed between the different methods, but the correlation was the function of characteristic of matrices. Significant matrix effect from the presence of phosphor was observed in the case of some samples, while the change of C/H ratio could not result notable matrix effect.     

A new equation for wavelength dispersive x-ray fluorescence analysis without standards

We derive an iteration equation for calculation of the concentrations of the elements in X-ray fluorescence analysis without standards. It does not require calculation of the intensity of primary spectra, which can excite the characteristic fluorescent X-ray, so its calculation is simpler. The experiments show that the results derived by the method without standards converged to those by chemical analysis, after three to four iterative calculations. The influence of the configuration of the specimen is negligible.     

Quantitative trace analysis with X-ray fluorescence in the scanning electron microscope

The potential of a scanning electron microscope will be enhanced markedly by adapting the X-ray fluorescence for material analysis. The illuminating system röntgenbox enables the analyst to execute analyses in the concentration range from 100 percent down to the low ppm range without time consuming preparation steps. X-ray intensities of traces are measured for different anodes in the elemental range fromZ=11 to 90 (sodium to thorium).     

Deposition of complex multielemental thin films

Modern condensed-matter physics is increasingly concerned with the design, synthesis, analysis, and exploitation of chemically complex materials and structures. Complex metal oxides and strongly correlated electron systems such as YBa₂Cu₃O_7−x and La_1−xSr_xMnO₃ are paradigmatic examples. Their production in the form of high-quality thin films is of both technological and fundamental importance and has stimulated a concerted effort in the last two decades to find and optimize efficient techniques to this end. This review discusses the physics behind and the requirements for synthesizing high-quality films of such materials and examines fundamental aspects of the growth processes associated with magnetron sputtering and pulsed laser deposition, the two techniques which presently offer the best solutions in this burgeoning field.     

Quantitative X-ray fluorescence analysis of an Egyptian faience pendant and comparison with PIXE

The X-ray fluorescence (XRF) technique is a common choice in the archaeometric field for in situ investigations with portable instruments. This work shows that XRF portable systems can be used for quantitative analyses using appropriate software, obtaining a similar accuracy to that provided with other techniques such as particle-induced X-ray emission (PIXE), as shown for an Egyptian faience pendant and for two glass standards.     

X-ray fluorescence analysis of rocks

Summary Modern methods for the determination of various elements in geological materials by XRFA are reviewed. XRFA theory and metrological characteristics are discussed in detail.

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Röntgenfluorescenzanalyse von Gesteinen

     

Preliminary homogeneity study of in-house reference material using neutron activation analysis and X-ray fluorescence

Summary Although many biological reference materials for quality control of trace element analysis are commercially available, there is still a need for additional local materials for special matrices. In the Latin American region a preliminary study has been commenced involving analytical strategies for the characterization of in-house reference material. A biological sample, prepared in Brazil, constitutes the first regional attempt to prepare reference material. It was analyzed by neutron activation analysis (NAA) and X-ray fluorescence (XRF) to verify its homogeneity. The determination of the trace elements and certain major elements was carried out by instrumental NAA. Trace elements such as Cd, Mn, Mo and Cu were determined using NAA with radiochemical separations to improve the sensitivity and precision. XRF was applied only to major constituents and some trace elements with concentration of more than 10 g/g. From a total of 18 elements analyzed, only Fe, Cr and Sc were not homogeneously distributed.     

Multielement analysis of standard reference materials with total reflection X-ray fluorescence (TXRF)

Summary X-Ray fluorescence analysis with total-reflected exciting beam (TRXF) represents a comparatively new development among the multielement methods. The main application of this method is the analysis of liquid samples. Furthermore, the measurements of suspensions and dust samples are practicable. With regard to sample preparation, execution and results information in various applications is at present available. This report gives a survey of advantages and restrictions of TXRF in soil science. After the digestion of various reference materials in two different ways, measurements were performed by TXRF. The elements Ca, Ti, Cr, Mn, Fe, Ni, Cu, Zn, Rb, Sr, Ba and Pb were taken into consideration.

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Multielement-Analyse von Standard-Referenzmaterialien mit der Totalreflexions-Röntgenfluorescenz (TRFA)

     

Calibration of reference materials for total-reflection X-ray fluorescence analysis by heavy ion backscattering spectrometry

Total-reflection X-ray fluorescence (TXRF) is widely used for the control of metallic contamination caused by surface preparation processes and silicon materials. At least three companies supply a variety of TXRF systems to the silicon integrated circuit (IC) community, and local calibration of these systems is required for their day to day operation. Differences in local calibration methods have become an issue in the exchange of information between IC manufacturers' different FABs (Fabrication Facility) and also between silicon suppliers and IC FABs. The question arises whether a universal set of fluorescence yield curves can be used by these different systems to scale system sensitivity from a single element calibration for calculation of elemental concentrations. This is emphasized by the variety of experimental conditions that are reported for TXRF data (e.g. different angles of incidence for the same X-ray source, different X-ray sources, etc.). It appears that an instrumental factor is required. We believe that heavy ion backscattering spectrometry (HIBS) provides a fundamental method of calibrating TXRF reference materials, and can be used in calculating this instrumental factor. In this paper we briefly describe the HIBS system at the Sandia National Laboratories HIBS User Facility and its application to the calibration of TXRF reference materials. We will compare HIBS and TXRF mapping capabilities and discuss the issues associated with the restrictions of some older TXRF sample stages. We will also discuss Motorola's cross-calibration of several TXRF systems using different elements as references.     

X射线荧光光谱分析

作为《分析试验室》定期评述“X射线荧光光谱分析”系列评论第八篇,本文收集国内学者在1998年7月至2000年6月期间公开发表在国内外期刊和国际会议文集上的129篇论文,并对此期间对我国X射线荧光光谱分析的概况、发展和国际上的地位进行了讲述,内容包括仪器及维修、基体校正、数据处理方法、谱分析方法的研究、标样及样品制备、全反射X射线荧光光谱、同步辐射光源X射线荧光光谱、粒子激发X射线发射、X射线荧光光谱分析方法研究及其应用。     

X-ray Peltier cooled detectors for X-ray fluorescence analysis

The recent results on development of X-ray Si(Li), Si-planar and CdTe p-i-n detectors cooled by Peltier coolers for fabrication of laboratory and portable XRF analysers for different applications are discussed.

Low detection limits of XRF analysers are provided by increasing of detectors sensitive surface; improvement of their spectrometrical characteristics; decreasing of front-end-electronics noise level; Peltier coolers and vacuum chambers cooling modes optimization.

Solution of all mentioned tasks allowed to develop Peltier cooled detectors with the following performances:

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Advantages and disadvantages of all types of detectors for X-ray fluorescence analysis are compared. Spectra are presented. Application of different XRF analysers based on developed detectors in medicine, environmental science, industry, cryminalistics and history of art are demonstrated.