A fundamental parameter-based quantification scheme for confocal XRF was applied to sub-micron synchrotron radiation X-ray fluorescence (SR-XRF) data obtained at the beamline P06 of the Deutsches Elektronen-Synchrotron (DESY, Hamburg, Germany) from two sections C0033-01 and C0033-04 that were wet cut from rock fragment C0033 collected from Cb-type asteroid (162173) Ryugu by JAXA’s Hayabusa2 mission. Trace-element quantifications show that C0033 bulk matrix is CI-like, whereas individual mineral grains (i.e., magnetite, pyrrhotite, dolomite, apatite and breunnerite) show, depending on the respective phase, minor to strong deviations. The non-destructive nature of SR-XRF coupled with a new PyMca (a Python toolkit for XRF data analysis)-based quantification approach, performed in parallel with the synchrotron experiments, proves to be an attractive tool for the initial analysis of samples from return missions, such as Hayabusa2 and OSIRIS-REx, the latter returning material from a B-type asteroid (101955) Bennu in 2023. Graphical Abstract

Millimetre-sized primordial rock fragments originating from asteroid Ryugu were investigated using high energy X-ray fluorescence spectroscopy, providing 2D and 3D elemental distribution and quantitative composition information on the microscopic level. Samples were collected in two phases from two sites on asteroid Ryugu and safely returned to Earth by JAXA’s asteroid explorer Hayabusa2, during which time the collected material was stored and maintained free from terrestrial influences, including exposure to Earth’s atmosphere. Several grains of interest were identified and further characterised to obtain quantitative information on the rare earth element (REE) content within said grains, following a reference-based and computed-tomography-assisted fundamental parameters quantification approach. Several orders of magnitude REE enrichments compared to the mean CI chondrite composition were found within grains that could be identified as apatite phase. Small enrichment of LREE was found for dolomite grains and slight enrichment or depletion for the general matrices within the Ryugu rock fragments A0055 and C0076, respectively.

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.

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 <10 p.p.m. for 1 s acquisition at 18 keV) show that PUMA is a competitive state-of-the-art beamline, providing several high-profile and high-in-demand analytical methods while maintaining applicability towards a wide range of heritage-oriented sciences.

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.

Combined X-ray-based spectroscopy techniques were applied to investigate arsenic (As) bioaccumulation in earthworms (Eisenia andrei) exposed to six field-collected polluted soils (58-13 330 mg As kg-1). After 14 days of exposure to the arsenious soils, the As distribution in earthworms was examined by micro-X-ray fluorescence spectroscopy (μXRF), after epoxy resin embedding and preparing thin sections. Similar to μXRF data, XRF-computed tomography (XRF-CT) confirmed As accumulation in the coelom of intact earthworms. Therefore, total-reflection XRF was used to determine total As within both the whole earthworm's body (AsE) and coelomic fluid extracts (AsF). Bioaccumulation data (AsE and AsF) were thereafter evaluated in relation to total As concentration in soils (AsT) and to As mobile fraction in soils. A significant linear correlation (R2 = 0.97) was found between AsE and AsF, indicating that the As sequestrated into the coelomic fluid may reflect the total body concentration. Therefore, we may conclude that the As concentration in the coelomic fluid can be used as an index of As availability. This paper demonstrates that by combining different laboratory X-ray analytical techniques, compartmentalization and bioavailability of potentially toxic elements can be visualized and quantified within indicator-living organisms, thus contributing to an improved risk assessment for contaminated soils.

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 São 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.

The study presents the application of combined micro-Spatially Offset Raman Spectroscopy (micro-SORS) and confocal X-ray fluorescence (confocal XRF) to the non-destructive investigation of micrometer scale stratified painted systems.

High-resolution X-ray computed tomography (μCT) is nowadays an established technique for material characterization. However, the technique only yields morphological information, and the composition of the object can only be retrieved based on an educated guess. On the other hand, three-dimensional highresolution X-ray fluorescence spectroscopy (μXRF) is an analytical technique that yields the chemical composition of a sample. In the past, several efforts have been made to combine both methods. Typically, they apply both techniques at different setups, and register the results [1,2]. One notable system developed earlier combines micro-CT and full-field XRF in one apparatus [3].

Multilevel interactions among nutrients occur in the soil-plant system. Among them, Fe and Zn homeostasis in plants are of great relevance because of their importance for plant and human nutrition. However, the mechanisms underlying the interplay between Fe and Zn in plants are still poorly understood. In order to elucidate how Zn interacts with Fe homeostasis, it is crucial to assess Zn distribution either in the plant tissues or within the cells. In this study, we investigated the subcellular Zn distribution in Fe-deficient leaf cells of cucumber plants by using two different approaches: cellular fractionation coupled with inductively coupled plasma mass spectrometry (ICP/MS) and nanoscopic synchrotron X-ray fluorescence imaging. Fe-deficient leaves showed a strong accumulation of Zn as well as a strong alteration of the organelles’ ultrastructure at the cellular level. The cellular fractionation-ICP/MS approach revealed that Zn accumulates in both chloroplasts and mitochondria of Fe deficient leaves. Nano-XRF imaging revealed Zn accumulation in chloroplast and mitochondrial compartments, with a higher concentration in chloroplasts. Such results show that (i) both approaches are suitable to investigate Zn distribution at the subcellular level and (ii) cellular Fe and Zn interactions take place mainly in the organelles, especially in the chloroplasts.

1. X-ray Microspectroscopy and Imaging group (XMI), Department of Chemistry, Ghent University, Krijgslaan 281 (S12), B-9000 Ghent, Belgium 2. Analytical, Environmental and GeoChemistry, Chemistry Department, VUB, Pleinlaan 2, B-1050 Brussels, Belgium 3. UGCT-RP, Department of Physics and Astronomy, Ghent University, Proeftuinstraat 86/N12, B-9000 Ghent, Belgium * Corresponding author, Brecht.Laforce@UGent.be

The study of La Famille Soler using non-invasive imaging, molecular, structural, and elemental analysis allowed the re-examination of changes of the work. Considered as the earliest of Picasso's versions of Le dejeuner sur l'herbe by E. Manet, evidence suggests that an underlying landscape painted by Vidal in 1903 also referred to Manet's masterpiece. On the other hand, new results suggest that the cubist sketch undertaken by Picasso in 1912, prior to the current blue background, could be an uncompleted transformation of Vidal's landscape into synthetic cubism. Through study the main pigments used in the underlying compositions were successfully identified.

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.

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.