A wavelength dispersive spectrometer which consists of a flat crystal analyser and a position sensitive proportional counter has been developed for X-ray fluorescence analysis using synchrotron radiation. The advantages of this spectrometer are high energy resolution, multielemental nature, and high efficiency, and these match well "with the high brightness synchrotron X-ray source. The minimum detection limits are of the order of ppm or pg. An application to elemental mapping has also been demonstrated. The present system is useful for practical analysis of small samples or small regions.

The semi-quantitative analysis, which is called ‘Standardless Analysis’, plays a major role in X-ray fluorescent analysis, especially in the field of research and development. The main feature of the semi-quantitative analysis is the fact that the composition of a sample can be obtained directly from a qualitative scan without any prior knowledge of the sample.

The use of a field portable XRF analyzer incorporating a semiconductor, mercuric iodide, energy dispersive spectrometer is described with emphasis on the benefits of high resolution x-ray detection for rapid screening of hazardous metallic wastes. Results are presented of “in-situ” and “prepared sample” soil measurement for different sites to show the potential of Fundamental Parameter analysis to obtain acceptable quality data with minimum calibration effort, obviating the need for site-specific standards.

A new experimental calculation method for polydisperse (i.e. heterogeneous) multicomponent material analysis has been developed using the dependence of element fluorescence intensity on the particle size and its distribution in the specimen. It is shown that correction of the influence of matrix particle size is possible using this experimental calculation method. For its application, the information on particle size distribution for each of the components is sufficient. Sample preparation includes only the pelleting of specimens under standard conditions. The efficiency of the method proposed is demonstrated by the analysis of the multicomponent mixtures of welding materials.

An x-ray microfluorescence (XRMF) spectrometer has been designed and fabricated at NIST for multi-point compositional analysis of small samples with x-ray beam sizes on the order of 50 micrometers or greater. This system was developed as part of an industrial cooperative research agreement with Kevex Instruments, Inc., San Carlos, CA., and consists of commercially available components incorporated in an aluminum vacuum chamber (see Figs. 1 and 2).

Refraction effects cause the effective 2d spacing of multilayers to vary so that the simple Bragg equation is not applicable when such devices are used for soft X-ray spectroscopy. This paper describes how the refraction term can be determined experimentally. These results compare well with dispersion and absorption terms calculated from atomic scattering factors.

A method of semiconductor detector calibration by variation of the incidence angle of the x-radiation is discussed.

A monochromatic and linear polarized X-ray beam obtained by a Bragg reflection of a characteristic tube line under 90° on single crystals can be used as a EDXRF excitation source in a triaxial beam geometry in order to profit by the polarization effects reducing the scattering background in the fluorescence spectrum, A systematic selection procedure for 55 single crystals suitable for Bragg reflection was established. The selection procedure takes the following conditions and criteria into account. First of all the existence of appropriate lattice planes hkl fulfilling the Bragg reflection condition and having low Miller indices as well as a Bragg angle close to 45° ensures a high degree of polarization. Furthermore the integrated reflectivity Ri for these lattice planes should be as high as possible. For the validity of the formula for Ri of an ideal mosaic crystal, the effects of primary and secondary extinction as well as of true absorption have to be considered. The critical limits of these parameters are calculated. The results of this systematic crystal selection procedure for the characteristic Kα lines of Cr, Cu, Mo and Ag tubes are presented.

We propose a method, by absorption [1,2,3,4], of determination of the X-ray spectrum emitted by a flash X-ray radiography generator. This approach leads to an ill posed inverse problem very sensitive to the measures precision.

We improve the robustness of the method by introduction of a smoothness constraint on the X-ray spectrum to reconstruct. We also propose an automatic choice of the weight between the measurement and the constraint by using a cross-validation technique.

We present an application on an unusual flash X-ray radiography generator - i.e. 75 ns of duration pulse, 6.5 MeV of maximum energy, 350 Rad for dose - for which an instrument of direct measure has not yet been found.

In general Latin America countries function differently in respect to the rest of the world because of their geographic allocations, economic and social situations. The areas of science and technologies are not excluded from this general rule. Thus, the following question arises : How has the area of analytical x-ray analysis techniques developed in Latin America in respect to the developed countries?

A method has been developed to simultaneously compute matrix corrections from a composite spectrum of multi-target energy-dispersive (EDXRF) and multicrystal wavelength—dispersive (WDXRF) x-ray fluorescence systems, A serial line installed between the WDXRF and EDXRF spectrometers via a PDF 11/34a computer allows acquired wavelength data to be digitally transformed into an energy spectrum. The low-energy x-ray information from the WDXRF unit is then coupled with the backscatter coherent/incoherent information from the EDXRF unit, enabling enhanced quantitative analysis for low-atomic-number (low-Z) elements. The peak resolution obtainable from the WDXRF spectra often removes the necessity for peak-overlap corrections.

Backscatter intensities obtained from the EDXRF unit are used to provide information on total sample mass and to correct for matrix effects. The resulting backscatter fundamental-parameter (BFP) calculations generally provide an accurate analysis of samples without prior knowledge of the sample matrix. Such an approach is particularly useful for samples in which quantities of carbon, oxygen, and other low-Z constituents cannot be explicitly determined.

Regions of interest (ROI) are created by the computer code “PREP” and processed by the BFP code "MSAP" an extension of the “SAP3” computer program for quantitative multielement analysis by energy-dispersive x-ray fluorescence,

Profile changes of copper Lα (L3-V) and Lβ (L2-V) X-ray fluorescence spectra are interpreted. It is shown that the intensity of the high energy shoulder of the Cu L X-ray spectra has a relation to the intensity of the so-called ‘shake-up’ satellite in 2p X-ray photoelectron spectra; the high energy shoulder of the divalent copper La is weak for covalent compounds and strong for ionic compounds. It is also shown that the Lβ/Lα intensity ratio changes with the change of copper concentration of the analyte as well as the change of chemical state of the analyte.

The XANES (X-ray absorption near edge structure) spectra of copper(II) ions in solid state and in solution of the square-planar copper(II) complexes with tetraaza macrocycles were measured. The peaks in the measured XANES spectra shifted to lower energy side with increasing the electron density of central copper(II) ions. The molecular orbital calculations for the complexes were carried out by the DV-Xα method, and the theoretical XANES spectra were estimated. The clear chemical shift obtained by this XANES study is evaluated and leads to a new concept of π-back donation between the copper(II) complexes and counter anion in aqueous solution.

The major advantage of secondary-target X-ray fluorescence analysis is the enchancement of sensitivity and detection limit of an element or small group of elements with similiar atomic numbers by selecting a target material which produces X-rays slightly higher than the absorption edges of the analysis of interest. Secondary target excitation systems are, however, being employed for simultaneous determinations of a large range of elements. Thus, it was decided to compare the application of a simple secondary target X-ray fluorescence system with excitation from a Cd-109 annular radioisotope source.

A simple secondary target X-ray fluorescence system was constructed and optimized which operates at less than 800 kilowatts. The “relative” elemental sensitivities of this system. and a radioisotope system with a Cd-109 annular source were compared by the analysis of the 1-2-3-multi-spectral standard from Chemplex which contains 1.23% of 53 elements. The characteristic X-rays were collected with the same Si(Li) detector and analyzed with the same Apple lie microprocessor with a Nucleus ADC/interface card. Finally, the secondary target system described herein with a molybdenum X-ray tube and zirconium or cadmium target produced similiar elemental sensitivities as a Cd-109 annular source of about 7.5 mCi and 5.0 mCi intensity respectively.

The exact compositions of the Victoria Crosses held in custody by the Australian War Memorial were needed so that its conservation staff could formulate a proper strategy for their conservation. This analytical study not only provided the required information but it resolved important ambiguities in the historical record.

In recent years, for the development of magnetic tape, it has become increasingly important that the elemental content be determined accurately and rapidly. In the past, the elemental content of magnetic tape was determined by calibration analysis using a wavelength dispersive X-ray fluorescence spectrometer(WDXRF). For calibration analysis many standard samples and large amount of sample were needed. Preparation of sample for calibration analysis, as well as for inductively coupled plasma emission spectral analysis(ICP) was difficult. On the other hand, for thin layer fundamental parameter analysis(we call TLFP) using a WDXRF, a few standard samples and l.pss sample are needed and preparation of the sample is easy. The superiority of TLFP analysis can be seen In comparison with calibration analysis and IOP analysis in Table 1. For this reason, this study has established a method for accurate and rapid determination of the elemental composition of oxide magnetic tape by TLFP analysis using a WDXRF.

Since Bednortz and Muller discovered high Tc oxide superconductors in 1986. many oxide superconductors are synthesized by many workers. These are YBCO system (Tc 90 K), BPSCCO system (110 K) and TBCCO system (125 K). Even now, the study of preparing higher Tc superconductors has been continued. The starting materials, in which the compositions are deiicatly variec, are mixed and high Tc oxide superconductors are prepared.

The problem of background radiation in X-ray fluorescence trace element analysis of fused-glass iron ore samples is addressed. A first-order model of coherent and Comptcn scattering with primary absorption is presented and used to correct measurements. Overlap coefficients for elements in iron ores are presented. The importance of these corrections is demonstrated. The accuracy achieved with X-ray measurements after background corrections compares well with the accuracy of chemical analysis.

Objects of art and archaeology are relicts of the past, and art historians, archaeologists and conservators are constantly concerned with the questions of where, when or by whom such artifacts were made. Usually stylistic considerations can provide answers to these questions, but as styles were sometimes copied at locations and times quite different from those for which they were most characteristic, material analysis is often essential when one is attempting to infer how and of what materials an object was made. The use of several compounds e.g. as pigments in paintings, or the deliberate alloying of Cu with Sn, As, Sb and Pb, has varied greatly from region to region and from time to time and can be used to infer the geographic origin of an object or at least the origin of the materials, out of which it was made.

XRF and Ion mfcroprobe analyses of fossils of known and uncertain provenance from the Lower-Middle Pleistocene locality of Kanjera. Kenya, are reported. The goal of this study was to develop a nondestructive technique of provenancixig fossils, which could be applied to the Kanjera sample. The fossils of known provenance were collected in the excavations of the 1987 Smithsonian Expedition. Three fossils of uncertain provenance, two specimens of Theropithecus oswaldi and a hominid fossil, were analyzed as test cases.

Both qualitative and quantitative XRF analyses of Kanjera fossils were carried out. In the qualitative analysis, the elemental peak areas from each fossil's XRF spectrum were calculated and normalized to the peak area of the incoherently scattered radiation. Results of the analysis showed that fossils from the Lower-Middle Pleistocene Kanjera Beds, for the most part, had higher levels of yttrium (Y) and zirconium (Zr) than those of the younger Apoko (Ap) Bed. black cotton soil (BCS) and modem bones (MD). The relative concentrations of uranium (U) v strontium (Sri and thorium (Th) were diagnostic of the Kanjera Bed of origin. These findings were confirmed by quantitative XRF and ion microprobe analyses of a subsample of Kanjera fossils. The T. oswaldi and hominid fossils had trace element concentrations suggestive of K2 and BCS provenances, respectively. These findings provide a framework for the qualitative XRF provenancing of other surface collected fossils from the locality.