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This chapter focuses on the basic principles of X-ray fluorescence (XRF) and micro-XRF imaging applicable to cultural heritage research, presenting basic figures of merit and application examples based on the use of advanced laboratory and synchrotron radiation sources. Related methods of analysis making use of absorption edge phenomena by X-ray absorption spectroscopy, including X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopy will also be discussed.

A novel 3D elemental and morphological analysis approach is presented combining X-ray computed tomography (μCT), X-ray fluorescence (XRF) tomography, and confocal XRF analysis in a single laboratory instrument (Herakles). Each end station of Herakles (μCT, XRF-CT, and confocal XRF) represents the state-of-the-art of currently available laboratory techniques. The integration of these techniques enables linking the (quantitative) spatial distribution of chemical elements within the investigated materials to their three-dimensional (3D) internal morphology/structure down to 1-10 μm resolution level, which has not been achieved so-far using laboratory X-ray techniques. The concept of Herakles relies strongly on its high precision (around 100 nm) air-bearing motor system that connects the different end-stations, allowing combined measurements based on the above X-ray techniques while retaining the coordinate system. In-house developed control and analysis software further ensures a smooth integration of the techniques. Case studies on a Cu test pattern, a Daphnia magna model organism and a perlite biocatalyst support material demonstrate the attainable resolution, elemental sensitivity of the instrument, and the strength of combining these three complementary methodologies.

Analytical chemistry 92(1), 1106-1113 (2020). doi:10.1021/acs.analchem.9b04176, Detection of rare earth elements (REE) is commonly performed with destructive techniques such as (LA)-ICPMS or coupled to a destructive sample preparation. When investigating unique geological samples, such as cometary, asteroidal, or interstellar material from sample return missions or inclusions in deep Earth diamonds, a nondestructive method is preferred. The presented nondestructive highly sensitive wavelength-dispersive X-ray fluorescence spectroscopy (WD-XRF) technique is designed to measure the L-lines of REE between 4.5 and 7 keV with a sensitivity down to the ppm level. REE fluorescence L-lines are often only separated by a few eV from neighboring XRF-lines and cannot be resolved by an energy dispersive approach especially in the presence of transition metal K-lines. In our spectrometer the characteristic X-rays emitted by the sample are dispersed by a fixed Ge(111) analyzer crystal over the active area of an energy dispersive pn-charge-coupled-device (pnCCD) detector, enabling high energy resolution detection of X-rays differentiated by their corresponding Bragg angles. The use of an energy-dispersive 2D detector enables the simultaneous acquiring of XRF-lines while eliminating any ambiguities due to potential contribution from higher order diffraction effects or other diffraction planes and thereby increases the sensitivity by reducing the (scatter) background. This detection method shows an energy resolution of 12 eV for the Ti–Kα fluorescence line and has a sensitivity down to 0.50 ppm for REE L-lines. The method was optimized specifically for the nondestructive analysis of inclusions in deep Earth diamonds, yielding in situ quantitative information about up-to-now inaccessible elemental (REE) composition patterns together with the more abundant transition metals like Ti, Cr, Mn, and Fe. This information is of great importance to decipher the role that deep Earth plays in the global carbon and fluid cycle., Published by American Chemical Society, Columbus, Ohio

At the French synchrotron facility SOLEIL, a new X-ray imaging facility PUMA (Photons Utilisés pour les Matériaux Anciens) has been made available to scientific communities studying materials from cultural heritage. This new instrument aims to achieve 2D and 3D imaging with microscopic resolution, applying different analytical techniques including X-ray fluorescence spectroscopy (XRF), X-ray absorption spectroscopy (XAS), X-ray diffraction and phase-contrast imaging. In order to discover its capabilities a detailed analytical characterization of this beamline as an analytical and imaging tool is deemed necessary. In this work, (confocal) XRF and XAS analyses are demonstrated using the Seymchan pallasite meteorite and an Antarctic unmelted micrometeorite as case studies. The obtained spatial resolution (2 µm × 3 µm) and sensitivity (detection limits

A new, commercially available, mobile system combining X-ray diffraction and X-ray fluorescence has been evaluated which enables both elemental analysis and phase identification simultaneously. The instrument makes use of a copper or molybdenum based miniature X-ray tube and a silicon-Pin diode energy-dispersive detector to count the photons originating from the samples. The X-ray tube and detector are both mounted on an X-ray diffraction protractor in a Bragg-Brentano theta:theta geometry. The mobile instrument is one of the lightest and most compact instruments of its kind (3.5 kg) and it is thus very useful for in situ purposes such as the direct (non-destructive) analysis of cultural heritage objects which need to be analyzed on site without any displacement. The supplied software allows both the operation of the instrument for data collection and in-depth data analysis using the International Centre for Diffraction Data database. This paper focuses on the characterization of the instrument, combined with a case study on pigment identification and an illustrative example for the analysis of lead alloyed printing letters. The results show that this commercially available light-weight instrument is able to identify the main crystalline phases non-destructively, present in a variety of samples, with a high degree of flexibility regarding sample size and position. (C) 2015 Elsevier B.V. All rights reserved.

A novel plug-and-play setup based on polycapillary X-ray optics enables three-dimensional (3D) confocal X-ray fluorescence (XRF) and X-ray absorption spectroscopy down to 8 × 8 × 11 μm3 (17 keV) at the European Synchrotron Radiation Facility Collaborative Research Group Dutch–Belgian Beamline, BM26A. A complete description and analytical characterization is presented, together with two recently performed experimental cases. In Deep Earth diamond Sao Luiz-Frankfurt am Main 16, an olivine-rich inclusion was mapped with full 3D XRF elemental imaging. The preliminary tests on Iron Gall ink contained in an historical document, a letter from the court of King Philip II of Spain, reveal both the delicate nature of Iron Gall ink and the lack of Fe–Ni chemical bonding.

A new three-dimensional (3D) micro X-ray fluorescence (μXRF) methodology based on a novel 2D energy dispersive CCD detector has been developed and evaluated at the P06 beamline of the Petra-III storage ring (DESY) in Hamburg, Germany. This method is based on the illumination of the investigated sample cross-section by a horizontally focused beam (vertical sheet beam) while fluorescent X-rays are detected perpendicularly to the sheet beam by a 2D energy dispersive (ED) CCD detector allowing the collection of 2D cross-sectional elemental images of a certain depth within the sample, limited only by signal self-absorption effects. 3D elemental information is obtained by a linear scan of the sample in the horizontal direction across the vertically oriented sheet beam and combining the detected cross-sectional images into a 3D elemental distribution data set. Results of the 3D μXRF analysis of mineral inclusions in natural deep Earth diamonds are presented to illustrate this new methodology.

X-ray absorption near-edge structure (XANES) spectroscopy is a well-known nondestructive technique that allows for chemical state and local structure determination. Spatially resolved oxidation state imaging is possible performing full-field transmission mode XANES experiments, providing chemical state information on the illuminated sample area, but these experiments are limited to thin, concentrated samples. Here we present the use of a unique energy dispersive (ED) pnCCD detector, the SLcam, for full-field fluorescence mode XANES experiments, thereby significantly relaxing the constraints on sample thickness. Using this new detection methodology, spatially resolved chemical state information on millimeter-sized sample areas can be obtained with microscopic resolution in moderate measuring times (less than 15 h), obtaining a XANES profile for each of nearly 70,000 points in a single measurement without the need of scanning the sample through the beam. Besides a description of the use of this detector for micro-XANES applications, we also present the proof of concept for fluorescence mode micro-XANES using a Fe(0)/Fe2O3 model sample and a Nitisol soil sample, which was measured to obtain iron chemical state distribution information.

“Mad Meg”, a figure of Flemish folklore, is the subject of a famous oil-on-panel painting by the Flemish renaissance artist Pieter Bruegel the Elder, exhibited in the Museum Mayer van den Bergh (Antwerp, Belgium). This article reports on the in situ chemical characterization of this masterpiece by using currently available state-of-the-art portable analytical instruments. The applied non-destructive analytical approach involved the use of a) handheld X-ray fluorescence instrumentation for retrieving elemental information and b) portable X-ray fluorescence/X-ray diffraction instrumentation and laser-based Raman spectrometers for obtaining structural/molecular information. Next to material characterization of the used pigments and of the different preparation layers of the painting, also the verification of two important historical iconographic hypotheses is performed concerning the economic way of painting by Brueghel, and whether or not he used blue smalt pigment for painting the boat that appears towards the top of the painting. The pigments identified are smalt pigment (65% SiO2 + 15% K2O + 10% CoO + 5% Al2O3) for the blue color present in all blue areas of the painting, probably copper resinate for the green colors, vermillion (HgS) as red pigment and lead white is used to form different colors. The comparison of blue pigments used on different areas of the painting gives no differences in the elemental fingerprint which confirms the existing hypothesis concerning the economic painting method by Bruegel.

Analytical chemistry 89(3), 2123 - 2130 (2017). doi:10.1021/acs.analchem.6b04828, Using X-ray absorption near edge structure (XANES) spectroscopy, information on the local chemical structure and oxidation state of an element of interest can be acquired. Conventionally, this information can be obtained in a spatially resolved manner by scanning a sample through a focused X-ray beam. Recently, full-field methods have been developed to obtain direct 2D chemical state information by imaging a large sample area. These methods are usually in transmission mode, thus restricting the use to thin and transmitting samples. Here, a fluorescence method is displayed using an energy-dispersive pnCCD detector, the SLcam, characterized by measurement times far superior to what is generally applicable. Additionally, this method operates in confocal mode, thus providing direct 3D spatially resolved chemical state information from a selected subvolume of a sample, without the need of rotating a sample. The method is applied to two samples: a gold-supported magnesia catalyst (Au/MgO) and a natural diamond containing Fe-rich inclusions. Both samples provide XANES spectra that can be overlapped with reference XANES spectra, allowing this method to be used for fingerprinting and linear combination analysis of known XANES reference compounds., Published by American Chemical Society, Columbus, Ohio

Ovarian cancer is amongst the most common types of cancer in women, with a relatively low overall cure rate of approximately 30%. This is therefore an important incentive to urge for further research in order to maximize the chances of survival for these patients. Intraperitoneal chemotherapy with Cisplatin is an effective treatement for ovarian cancer; however, many questions still remain concerning the ideal treatment protocol and tumor resistance towards the drug, which should be resolved for optimal application of this therapy. For the first time in-vivo grown tumors treated with both hyper- and normothermic intraperitoneal chemotherapy have been studied using nano-XRF spectroscopy to examine the platinum (Pt) distribution within the analyzed tissues. These measurements prove Pt resides predominantly outsides the cancer cells in the stroma of the tissue. These findings indicate the resistance mechanism of the cancer cells prevents Cisplatin from diffusing through their cell membranes. This is an important addition to the existing knowledge on the resistance mechanism providing insights which might help to overcome this effect. In our aim to find the optimal treatment protocol, no significant differences were found between the two examined procedures. A more extensive data set will be needed to draw definite conclusions.

A new method for the quantification of X-ray fluorescence (XRF) was derived based on the fundamental parameter method (FPM). The FPM equations were adapted to accommodate the special case of confocal nano-XRF, i.e. X-ray nano-beam excitation coupled with confocal detection, taking into account the special characteristics of the detector channel polycapillary. A thorough error estimation algorithm based on the Monte Carlo method was applied, producing a detailed analysis of the uncertainties of the quantification results. The new FPM algorithm was applied on confocal nano-XRF data obtained from cometary dust returned by NASA's Stardust mission, recorded at beamline ID13 of the European Synchrotron Radiation Facility.

Using a significantly improved method for X-ray fluorescence (XRF) tomography with submicrometer spatial resolution, the fully three-dimensional (3D) distribution of main and trace elements from calcium to selenium was determined at a spatial resolution level of 200 nm within a unique (∼2 μm) comet coma particle brought to Earth by the National Aeronautical and Space Administration (NASA)’s Stardust mission. The measurements were based on synchrotron radiation XRF nanotomography that has been applied to the terminal particle located in an aerogel host, which was used to capture comet and interstellar grain particles in space. Using a symmetric dual-detector arrangement for the presented nano-XRF tomography measurements, a rotation angle of 180° was sufficient for the tomographic reconstruction. Dedicated correction algorithms were developed to correct for submicrometer-level distortions within the tomographic dataset arising from instabilities of the sample positioning system during data collection.

A combined micro-PIXE and micro-SRXRF method has been used for the characterization of impact materials collected at the well-known Barringer Meteor Crater. Elemental maps were recorded and concentrations were determined by micro-PIXE method for the major constituents of samples. Micro-SRXRF technique was used for the complementary measurement of medium and high atomic number elements, especially the siderophilic ones. Altogether, approximately 40 elements were analyzed. These results elucidate many steps of the formation mechanism of the various impact-metamorphosed objects.

The ID18F microprobe end-station of the European Synchrotron Radiation Facility (ESRF) is dedicated to precise and reproducible quantitative X-ray fluorescence analysis in the ppm level with ⩽5% accuracy for elements of Z ⩾19 and micron-size spatial resolution. In order to fulfill this requirement the precise monitoring and normalization of the intensity variation of the focused micro-beam is necessary. The various effects influencing the intensity variation, hence the stability of the μ-beam, were investigated by placing different detectors (miniature ionization chamber, photodiodes) into the monochromatic beam. The theoretical statistical error of the measured signal in each detector was estimated on the basis of the absorption and e − –ion-pair production processes and was compared with the measured statistical errors.

A new user end-station is under construction at the ESRF with collaboration between the Micro-Fluorescence, Imaging and Diffraction beamline (ID22) and the Micro and Trace Analysis Center (MITAC) of the University of Antwerp. The new end-station is dedicated to quantitative micro-fluorescence measurements. The analytical characteristics (degree of polarization of the incoming beam, absolute and relative detection limits) of the new set-up were investigated during preliminary experiments by using a temporary experimental set-up. Copyright © 2001 John Wiley & Sons, Ltd.

The various application possibilities of microscopic x-ray fluorescence and associated methods for the characterization and provenance analysis of objects and materials of cultural heritage value are discussed by means of a number of case studies. They include the trace analysis of historic glass, the analysis of corroded coins and statues in bronze and silver and the study of inks on historical documents. These studies are conducted by means of micro-XRF instruments installed at synchrotron beamlines and by means of laboratory equipment, some of which is easily transportable to the museum or archaeological site where the objects of interest are located. Copyright © 2000 John Wiley & Sons, Ltd.

The analytical characteristics, possibilities and limitations of a compact and easily transportable small-beam XRF instrument are described. The instrument consists of a compact, mini-focus Mo X-ray tube that is collimated to produce a sub-mm beam and a peltier-cooled PIN diode detector. Relative MDLs in highly scattering matrices are situated in the 10–100-ppm range; for metallic matrices featuring strong matrix lines, the MDLs of the instrument are approximately a factor 2 higher. Since only a small irradiation area is required, a simple micro-polishing technique that may be performed in situ in combination with the measurements is shown to be effective for the determination of the bulk composition of corroded bronze objects. As an example, a series of Egyptian bronze objects date from XXIInd Egyptian Dynasty (ca. 1090 bc ) to the Roman era (30 bc to 640 ad ) was analyzed in order to contribute to the very limited database on Cu–alloy compositions from this period.

We discuss the inherent difficulties that arise during "ground truth" characterization of the Stardust interstellar dust collector. The challenge of identifying contemporary interstellar dust impact tracks in aerogel is described within the context of background spacecraft secondaries and possible interplanetary dust particles and beta-meteoroids. In addition, the extraction of microscopic dust embedded in aerogel is technically challenging. Specifically, we provide a detailed description of the sample preparation techniques developed to address the unique goals and restrictions of the Interstellar Preliminary Exam. These sample preparation requirements and the scarcity of candidate interstellar impact tracks exacerbate the difficulties. We also illustrate the role of initial optical imaging with critically important examples, and summarize the overall processing of the collection to date.

The analytical characteristics of a laboratory-scale micro-X-ray fluorescence spectrometer, based on a rotating anode X-ray generator and capillary optics, are described. Usually, a microbeam 15 μm in diameter, derived from a copper or molybdenum anode operated at 45 kV, is used for sample irradiation. Elemental yields around the 1 count s−1(μg cm−2)−1 level are obtained, corresponding to absolute detection limits for thin samples in the 0.05–1 pg range and to relative MDL levels of 3–10 ppm for thick organic samples. The use of the instrument for studying (trace) element migration in Roman glass and for the nondestructive analysis of decorations on Japanese 18th century porcelain vases is described.

This chapter deals with the analytical applications of synchrotron radiation sources for trace-level analysis of materials on microscopic and submicroscopic scales. Elemental analysis with X-ray fluorescence is described in detail. Two-dimensional (2D) and three-dimensional (3D) analyses are discussed in their quantitative aspects. Related methods of analysis based on absorption edge phenomena such as X-ray absorption spectrometry (XAS) and near-edge scanning spectrometry (XANES) yielding molecular information, computerized X-ray fluorescence microtomography (XFCT) based on the penetrative character of X-rays, and microscopic X-ray diffraction (XRD) providing structural data on the sample are also briefly discussed. The methodological treatment is illustrated with a number of applications.

Raman spectroscopy and X-ray fluorescence (XRF) spectroscopy are often used as complementary techniques that are well suited for the analysis of art objects because both techniques are fast, sensitive, and noninvasive and measurements can take place in situ. In most of these studies, both techniques are used separately, in the sense that the spectra are evaluated independently and single conclusions are obtained, considering both results. This paper presents a data fusion procedure for Raman and XRF data for the characterization of pigments used in porcelain cards. For the classification of the analyzed points of the porcelain cards principal component analysis (PCA) was used. A first attempt was made to develop a new procedure for the identification of the pigments using a database containing the fused Raman-XRF data of 24 reference pigments. The results show that the classification based on the fused Raman-XRF data is significantly better than the classifications based on the Raman data or the XRF data separately. © 2011 Society for Applied Spectroscopy.

A confocal setup based on polycapillary half-lenses was used to demonstrate three-dimensional (3D) spatially resolved mu-XANES in fluorescence detection mode at the DUBBLE XAS station of the ESRF (BM26A). The incoming beam was focused using a polycapillary half-lens and a second glass polycapillary was placed in front of the energy dispersive detector to establish the confocal detection. The full-width-half-maxima along the main axes of the resulting ellipsoidal detection volume were 18.5 x 12.0 x 10.0 microm(3) at the Cu K-edge. The confocal mu-XANES mode is applied in the 3D resolved study of mineral inclusions in rare natural diamonds at the Fe K edge.

A focusing system based on a polycapillary half-lens optic has been successfully tested for transmission and fluorescence µ-X-ray absorption spectroscopy at a third-generation bending-magnet beamline equipped with a non-fixed-exit Si(111) monochromator. The vertical positional variations of the X-ray beam owing to the use of a non-fixed-exit monochromator were shown to pose only a limited problem by using the polycapillary optic. The expected height variation for an EXAFS scan around the Fe K-edge is approximately 200 µm on the lens input side and this was reduced to ∼1 µm for the focused beam. Beam sizes (FWHM) of 12–16 µm, transmission efficiencies of 25–45% and intensity gain factors, compared with the non-focused beam, of about 2000 were obtained in the 7–14 keV energy range for an incoming beam of 0.5 × 2 mm (vertical × horizontal). As a practical application, an As K-edge µ-XANES study of cucumber root and hypocotyl was performed to determine the As oxidation state in the different plant parts and to identify a possible metabolic conversion by the plant.

For the non-destructive identification of pigments and colorants in works of art, in archaeological and in forensic materials, a wide range of analytical techniques can be used. Bearing in mind that every method holds particular limitations, two complementary spectroscopic techniques, namely confocal ì-Raman spectroscopy (ì-RS) and ì-X-ray fluorescence spectroscopy (ì-XRF), were joined in one instrument. The combined ì-XRF and ì-RS device, called PRAXIS unites both complementary techniques in one mobile setup, which allows ì- and in situ analysis. ì-XRF allows one to collect elemental and spatially-resolved information in a non-destructive way on major and minor constituents of a variety of materials. However, the main disadvantages of ì-XRF are the penetration depth of the X-rays and the fact that only elements and not specific molecular combinations of elements can be detected. As a result ì-XRF is often not specific enough to identify the pigments within complex mixtures. Confocal Raman microscopy (ì-RS) can offer a surplus as molecular information can be obtained from single pigment grains. However, in some cases the presence of a strong fluorescence background limits the applicability. In this paper, the concrete analytical possibilities of the combined PRAXIS device are evaluated by comparing the results on an illuminated sheet of parchment with the analytical information supplied by synchrotron radiation ì-X-ray diffraction (SR ì-XRD), a highly specific technique.

This study deals with the process of zeolite formation in an agricultural soil artificially polluted by high amounts of Cu (15 mg of Cu/g of soil dry weight) and treated with fused coal fly ash at 30 and 60 degrees C and how this process affects the mobility and availability of the metal. As a consequence of the treatment, the amount of dissolved Cu, and thus its mobility, was strongly reduced, and the percentage of the metal stabilized in the solid phase increased over time, reaching values of 30% at 30 degrees C and 40% at 60 degrees C. The physicochemical phenomena responsible for Cu stabilization in the solid phase have been evaluated by EDTA sequential extractions and synchrotron radiation based X-ray microanalytical techniques. These techniques were used for the visualization of the spatial distribution and the speciation of Cu in and/or on the neo-formed zeolite particles. In particular, micro XRF (X-ray fluorescence) tomography showed direct evidence that Cu can be entrapped as clusters inside the porous zeolitic structures while,mu-XANES (X-ray absorption near edge structure) spectroscopy determinations revealed Cu to be present mainly as Cu(II) hydroxide and Cu(II) oxide. The reported results could be useful as a basic knowledge for planning new technologies for the on site physicochemical stabilization of heavy metals in heavily polluted soils.

Ibis work illustrates the development of X-ray fluorescence tomography and polycapillary based confocal imaging towards a three-dimensional (313), quantitative analytical method with lateral resolution levels down to the 2-20 mum scale. Detailed analytical characterization is given for polycapillary based confocal XRF imaging, which is a new variant of the 3D micro-XRF technique. Applications for 2D/3D micro-XR-F are illustrated for the analysis of biological (zooplankton) and geological samples (microscopic inclusions in natural diamonds and fluid inclusions in quartz). Based on confocal imaging, fully three-dimensional distributions of trace elements could be obtained, representing a significant generalization of the regular 2D scanning technique for micro-XRF spectroscopy. The experimental work described in this paper has been carried out at the ESRF ID18F microfluorescence end-station and at HASYLAB Beam Line L.

A three-dimensional (3D) variant of scanning micro X-ray fluorescence (XRF) is described and evaluated at the ID18F instrument of the European Synchrotron Radiation Facility (ESRF). The method is based on confocal excitation/detection using a polycapillary half-lens in front of the energy-dispersive detector. The experimental arrangement represents a significant generalization of regular two-dimensional (2D) scanning micro-XRF and employs a detector half-lens whose focus coincides with that of the focused incoming beam. The detection volume defined by the intersection of the exciting beam and the energy-dependent acceptance of the polycapillary optics is 100-350 mum(3). Minimum detection limits are sub-ppm, and sensitivities are comparable with regular scanning XRF. Next to the reduction of in-sample single/multiple scattering, the setup provides the possibility of sample depth scans with an energy-dependent resolution of 10-35 mum in the energy range of 3-23 keV and the possibility of performing 3D-XRF analysis by simple XYZ linear scanning. This provides a suitable alternative to X-ray fluorescence tomography. The method is illustrated with results of the analysis of solid inclusions in diamond and fluid inclusions in quartz.

We present recent results of fluorescence tomography experiments obtained on a variety of samples originating from the fields of Mineralogy, Space Sciences or Botany. The ID22 hard X-ray microanalysis beamline of the ESRF was used in scanning beam mode to record fluorescence spectra in pencil-beam collection mode for energies of 14 to 22.5 keV and micron-sized beamspots. Trace element concentrations of a few hundred ppm were successfully imaged in inhomogenous samples of less than 500 microns and resolutions up to 2 microns.

Experimental data and results from a detailed Monte Carlo (MC) simulation of X-ray Fluorescence, Compton and Rayleigh scattering tomography are presented. The MC model was developed by the authors for aiding the optimization and evaluation of synchrotron radiation induced X-ray fluorescence (SRXRF) experiments. The code simulates complete X-ray fluorescence spectra in the incident energy range of 1 - 100 keV, including K,L fluorescent lines and Compton, Rayleigh scattering contributions. This generalized simulation model describes the interactions between X-ray photons and heterogenous samples. The MC code was evaluated by comparisons of simulated and experimental X-ray fluorescent and scattering tomography data. These data were collected at HASYLAB, beamline L (polychromatic setup) and BW5 (monochromatic setup). Good agreement was found between experimental and simulated results.

Information included in auxiliary signals, i,e. incoherently and coherently scattered signals and transmitted beam intensities in x-ray fluorescence analysis (XRF), a selected channel in the scattered white synchrotron radiation and in the contents of selected hremsstrahlung channels in electron microprobe analysis (EMPA), can be extracted and exploited to complete the results of analyses. Such additional information is much more detailed when the devices are operating in the microprobe mode; however, this is not a necessary condition. The theoretical basis for the use of the auxiliary signals, in the sense proposed in this paper, is discussed. In situations where the main component is of essentially constant chemical composition but with variable density through the sample (wood of living trees, petrified wood, stalactites, coral structures-in general natural periodic structures) or with inclusions inside, the application of two kind of signals is preferable in XRF: the transmitted and scattered signal. For light organic matrices (cellulose, plastics), the information included in the Rayleigh or Compton signal is reversed in relation to the information from the transmission signals. The selected hremsstrahlung signal or the signal from the secondary electron spectrum can serve the same purpose if EMPA analysis is performed. In general, these signals provide auxiliary knowledge about the density of objects. An especially interesting situation is when the object is a chemical negative of the original, such as the distribution of silica in some kinds of petrilied wood with respect to the distribution of the cellulose in the original wood. Many original results of analyses are shown. Intercomparisons of the transmission images with the reversed scattered scans in light matrices are still scarce, while the observation of bremsstrahlung or secondary electron scans (in EMPA) and their scattered or transmission analogues (in XRF) for objects and their chemical negatives is demonstrated for the first time. Comprehensive results of the analyses of petrified wood and stalactites (EMPA and XRF) are presented.

The combined use of principal component analysis (PCA) and K-means clustering (KMC) for the segmentation and (semi-)quantitative calibration of multivariate μ-XRF data sets is proposed and evaluated. The usefulness of the method is compared with that of using PCA or KMC separately by discussing image sets derived from geological and archeometric samples.

μ-XRF is the microscopic equivalent of the well-established multielement analytical technique. In this paper, after comparing the interaction of X-ray photons, electrons and protons with matter and an introduction to synchrotron rings and microfocussing of X-rays, the instrumentation for μ-XRF is discussed, both for laboratory source and synchrotron based setups and the analytical characteristics of μ-XRF are contrasted to that of other microanalytical techniques. Also, this issue of quantification of μ-XRF data is addressed; the applicability of the method in archeological and geological analysis is illustrated.

A number of background estimation and modelling strategies suitable for evaluating energy-dispersive X-ray spectra by means of non-linear least squares fitting are evaluated and intercompared. As background modelling functions, exponential and linear combinations of mutually orthogonal polynomials are considered. These functions allow the shape of the background to be determined together with the photopeak intensities. As background estimation algorithms, an iterative stripping algorithm and a background channel selection procedure which is also based on the use of orthogonal polynomials are studied. The last two methods calculate the spectral background prior to the actual fitting process. For the intercomparison, the various methods were incorporated in the software package AXIL (Analysis of X-ray spectra by means of Iterative Least Squares). By using simulated spectra in which the intensity of all lines is a priori known, the accuracy and noise-sensitivity of the different background compensation strategies are evaluated. The method in which the background is modelled as a linear combination of orthogonal polynomials is identified as being the most robust and yielding the most accurate results.

The principles of design and manufacturing of the polymer planar x-ray lenses focusing in one and two directions, as well as the peculiarities of optical behaviors and the results of the lens test are reported in this paper. The methods of electron and deep x-ray lithography used in lens manufacturing allow the manufacture of ten or more x-ray lenses on one substrate; the lenses show focal lengths down to several centimeters for photon energies between 5 and 40 keV. The measured focus size was 105 nm for a linear lens with an intensity gain of about 407, and 300 x 770 nm for a crossed lens with an intensity gain of 6470.

Glass polycapillary optics are shown to be easy to use focusing optics for bending magnet XAS stations. These achromatic optics have acceptances of several mm horizontally and vertically, while their angular acceptances can be matched to the source divergence by the design of the polycapillary. A polycapillary half-lens based focusing system was successfully tested for transmission and fluorescence µ-XAS at the DUBBLE beamline (BM26A, ESRF) and the feasibility of confocal µ-XANES in fluorescence mode is presented. Transmission efficiencies of 25-45% with flux density gain factors of about 2000 and beam sizes of 10-20 µm were obtained in the 7-14 keV energy range. Although the polycapillary optic has a smoothly changing energy dependent transmission efficiency, the amplitude and shape of the EXAFS oscillations are not influenced by this. The focusing properties of the polycapillary lens cancel slight vertical motions of the incoming X-ray beam, resulting in a fixed µ-beam spot in the focal plane, making polycapillaries also suitable optic in combination with a non-fixed exit monochromator. In addition, by mounting a second polycapillary half-lens in front of an energy dispersive detector, a confocal set-up is obtained, which restricts the part of the sample seen by the detector to a microscopic volume of about 20×20×15 µm3 at the Fe K absorption edge for example.

Stardust is an interplanetary spacecraft launched on February 7, 1999, by NASA, whose primary purpose was to investigate the make up of comet Wild2 and its coma. A second goal of the project was the acquisition of interstellar dust. In order to facilitate the capture of the particles, the spacecraft was equipped with aerogel (highly porous silica foam with an extremely low density) collectors. After the return of Stardust to Earth on January 15, 2006, the acquired samples were distributed among more than 150 researchers worldwide, including the X-Ray Micro-spectroscopy and Imaging group of Ghent University (XMI-UGent). Each presented sample contains an elongated cavity (called track) produced by the impact and deceleration of a single comet coma particle through the aerogel. Multiple experiments were performed on such tracks and their terminal particle at the ESRF ID13 beamline using several non-destructive X-ray based methods such as conventional 2D scanning nano X-ray fluorescence (XRF) and confocal nano-XRF imaging. The latter technique is applied by mounting a polycapillary half-lens in front of the energy dispersive detector, thereby effectively reducing the volume defined by the intersection of the incoming beam and the sample to a volume defined by the acceptance of the polycapillary. A linear Fresnel lens assembly or a KB-mirror system, were used to reduce the dimensions of the incoming X-ray beam to the 200-300 nm level. The recorded XRF data have been evaluated using XMI-quant, a software package made by the XMI-UGent group in order to perform quantitative evaluation of micro-XRF spectra with special focus on data from confocal XRF imaging experiments. This software package includes an implementation of the fundamental parameter method allowing the analysis of the complex Stardust particles. The presented quantitative results confirm the earlier findings concerning the presence of Ca-Al-rich inclusions in the cometary dust.