Scanning X-ray nanodiffraction: from the experimental approach towards spatially resolved scattering simulations

An enhancement on the method of X-ray diffraction simulations for applications using nanofocused hard X-ray beams is presented. We combine finite element method, kinematical scattering calculations, and a spot profile of the X-ray beam to simulate the diffraction of definite parts of semiconductor nanostructures. The spot profile could be acquired experimentally by X-ray ptychography. Simulation results are discussed and compared with corresponding X-ray nanodiffraction experiments on single SiGe dots and dot molecules

Substratabhängigkeit des Grenzflächenschmelzens von Eis an heterogenen Grenzflächen : eine Röntgenstreustudie

The buried interface between ice and various substrates has been investigated by high-energy x-ray reflectometry at the high-energy beamline of the European Synchrotron Radiation Facility (ESRF). At temperatures close to the melting point interface melting of ice was observed. The correlation length and onset temperature of the premolten quasiliquid layer vary with the morphology of the substrate. The density of the quasi-liquid layer is 25% higher than the density of bulk water. We find that the extent of the interface melting of ice is related to the x-ray radiation dose.An der Hochenergie Messstation der Europäischen Synchrotron Strahlungsquelle (ESRF) wurde die vergrabene Grenzfläche zwischen Eis und verschiedenen Substraten mit hochenergetischer Röntgenreflektometrie untersucht. Das Grenzflächenschmelzen von Eis konnte bei Temperaturen nahe dem Schmelzpunkt beobachtet werden. Die Korrelationslänge und die Einsetztemperatur der quasiflüssigen Schicht hängt von der Morphologie des Substrats ab. Ihre Dichte ist 25% höher als die Dichte von Volumenwasser. Wir beobachten, dass der Grad des Grenzflächenschmelzens von der Röntgenstrahlungsdosis abhängt

Degradation of historical paper induced by synchrotron X-ray technical examination

International audienceThis research explores how intrinsic factors such as constituents and degradation state can impact the modifications incurred in aged papers during and after X-ray examination. To this end laboratory model papers, artificially aged, and eighteenth and nineteenth century archival documents, with and without additives (gelatin, calcium carbonate) and iron gallate ink, were exposed to Synchrotron X-ray radiation at doses commonly applied (7 Gy to 4 kGy). The threshold dose of 210 Gy previously shown to incur damage in unaged cotton papers falls in this range. Glycosidic scissions, hydroxyl free radicals, UV luminescence and yellowing were measured immediately after the irradiation, and were monitored over a period of three years. Cellulose depolymerization was lower in the aged papers, as well as in the papers containing calcium carbonate and gelatin, than in the unaged fully cellulosic papers. Compared to the papers with no additives, there were more hydroxyl free radicals in the papers with calcium carbonate and slightly less in the gelatin sized papers. UV luminescence and yellowing both appeared post-irradiation, with a delay of several weeks to months. The papers with iron gallate ink showed limited degradation in the low doses range, most probably due to recombination of the free radicals produced. Doses below 4 kGy did not cause yellowing or UV luminescence of the archival papers within the whole monitoring period. The archival papers in good conservation state depolymerized to the same extent as the model papers, while the most degraded archival papers were less impacted than the latter

Synchrotron X-ray microprobes: An application on ancient ceramics

International audienceSynchrotron X-ray µ-and nano-probes are increasingly affirming their relevance in cultural heritage applications, especially in material characterization of tiny and complex micro-sam-ples which are typical from archaeological and artistic artifacts. For such purposes, synchrotron radiation facilities are tailoring and optimizing beamlines and set-ups for CH, taking also ad-vantages from the challenges offered by the third-generation radiation sources. In ancient ceramics studies, relevant information for the identification of production centers and manufacture technology can be obtained in a non-invasive and non-destructive way at the micro-sample level by combining different SR based methods. However, the selection of appropriate beamlines, techniques and set-ups are critical for the success of the experiments. Fine and varnished wares (e.g., Attic and western-Greek colonial products) are an excellent case study for exploring challenges offered by synchrotron X-ray microprobes optimized to collect microchemical and phase-distribution maps. The determination of provenance and/or technological tracers is relevant in correctly classifying productions, often based only on ceramic paste, gloss macroscopic features or style. In addition, when these vessels are preserved in Museums as masterpieces or intact pieces the application of non-invasive approach at the micro sample is strictly required. Well-designed synchrotron µXRF and µXANES mapping experiments are able providing relevant clues for discriminating workshops and exploring technological aspects, which are fundamental in answering the current archaeological questions on varnished Greek or western-Greek colonial products

Short- and Long-Term Effects of X-ray Synchrotron Radiation on Cotton Paper

International audienceX-ray analytical techniques are increasingly being used to study manuscripts and works of art on paper, whether with laboratory equipment or synchrotron sources. However, it is difficult to anticipate the impact of X-ray photons on paper- and cellulose-based artifacts, particularly due to the large variety of their constituents and degradation levels, and the subsequent material multiscale heterogeneity. In this context, this work aims at developing an analytical approach to study the modifications in paper upon synchrotron radiation (SR) X-ray radiation using analytical techniques, which are fully complementary and highly sensitive, yet not frequently used together. At the molecular scale, cellulose chain scissions and hydroxyl free radicals were measured using chromatographic separation techniques (size-exclusion chromatography-multiangle laser light scattering-differential refractive index (SEC-MALS-DRI) and reversed-phase high-performance liquid chromatography-fluorescence detector-diode array detector (RP-HPLC-FLD-DAD)), while the optical properties of paper were characterized using spectroscopy (UV luminescence and diffuse reflectance). These techniques showed different sensitivities toward the detection of changes. The modifications in the cellulosic material were monitored in real time, within a few days, and up to 2 years following the irradiation to define a lowest observed adverse effect dose (LOAED). As paper is a hygroscopic material, the impact of the humidity in the environment was studied using this approach. Three levels of moisture content in the paper, achieved by conditioning the samples and irradiating them at different relative humidities (RHs), were studied (0, 50, 80% RH). It was shown that very low moisture content accelerated molecular and optical modificatio

Scanning X-ray nanodiffraction: From the experimental approach towards spatially resolved scattering simulations

An enhancement on the method of X-ray diffraction simulations for applications using nanofocused hard X-ray beams is presented. We combine finite element method, kinematical scattering calculations, and a spot profile of the X-ray beam to simulate the diffraction of definite parts of semiconductor nanostructures. The spot profile could be acquired experimentally by X-ray ptychography. Simulation results are discussed and compared with corresponding X-ray nanodiffraction experiments on single SiGe dots and dot molecules

Improved discrimination of biogenic and diagenetic elements in Palaeolithic mammoth ivory and bone from Hohle Fels Cave in the Swabian Jura of Southwestern Germany

International audienceMammoth ivory was used by humans to manufacture personal ornaments, sculptures or music instruments during the Upper Palaeolithic. These objects are among the first and most precious witnesses of ancient artistic behaviour. Archaeological ivory, however, has been subjected to complex alteration processes due to exchange with its burial environment over time. Therefore, it is necessary to understand the diagenetic phenomena in order to develop adequate conservation measures for ivory artefacts. The element-analytical study of ivory artefacts can shed light on these processes and can help to track the origin of these objects. In this work we studied twelve mammoth ivory samples and ten bone samples coming from the Palaeolithic site Hohle Fels located in the Swabian Jura. Mammoth bone samples were included in the study in order to find eventual differences in the diagenetic changes between ivory and bone material. We performed ion beam analysis (PIXE/PIGE) at the microfocus beamline of the accelerator NewAGLAE at C2RMF and micro-X-ray fluorescence (XRF) mappings at the PUMA beamline at synchrotron SOLEIL. The obtained PIXE/PIGE results are consistent with previous studies of ivories from Hohle Fels and other contemporaneous European sites in terms of possible site-specific (Zn, Br, Sr contents) and diagenetic markers (F content). XRF mappings and their semi-quantitative analyses confirm former observations and provide additional criteria for the classification of endogenous and exogenous elements. Based on our results we could not find significant difference in the diagenetic alterations between archaeological ivory and bone samples for the studied archaeological site

Practical advances towards safer analysis of heritage samples and objects

International audienceIn recent years, we have seen a significant increase in interest in the effects of irradiation used for analytical purposes on art, archaeological, palaeontological and palaeoenvironmental samples and objects. Among the main trends regarding ionising radiations used in X-ray, UV and ion beam experiments, we have observed a greater consistency in the description of the effects of irradiation, a number of quantitative studies, while several works studied in depth the corresponding chemical mechanisms and kinetics. We have also observed the development of analytical strategies and dedicated instruments to better detect and limit the effects of irradiation in real experiments on ancient samples and objects. Emerging trends include detailed mechanistic studies on specific systems, the development of statistical methods to reduce the doses required to study samples, and the development of early warning systems capable of feeding back into the experiment while an acquisition is in progress

Investigation of (micro-)meteoritic materials at the new hard X-ray imaging PUMA beamline for heritage sciences

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