TY - JOUR A1 - Hahn, Oliver A1 - Falkenberg, G. A1 - Pepponi, G. A1 - Streli, C. A1 - Wobrauscheck, P. T1 - Comparison of conventional and total reflection excitation geometry for fluorescence X-ray absorption spectroscopy on droplet samples N2 - X-ray absorption fine structure (XAFS) experiments in fluorescence mode have been performed in total reflection excitation geometry and conventional 45°/45° excitation/detection geometry for comparison. The experimental results have shown that XAFS measurements are feasible under normal total reflection X-ray fluorescence (TXRF) conditions, i.e. on droplet samples, with excitation in grazing incidence and using a TXRF experimental chamber. The application of the total reflection excitation geometry for XAFS measurements increases the sensitivity compared to the conventional geometry leading to lower accessible concentration ranges. However, XAFS under total reflection excitation condition fails for highly concentrated samples because of the self-absorption effect. T2 - 9th Conference on Total Reflection X-Ray Fluorescence analysis and Related Methods CY - Funchal, Portugal DA - 2002-09-08 PY - 2003 U6 - https://doi.org/10.1016/j.sab.2003.06.006 SN - 0584-8547 SN - 0038-6987 VL - 58 IS - 12 SP - 2239 EP - 2244 PB - Elsevier CY - Amsterdam AN - OPUS4-1499 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buzanich, Günter A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Streli, C. T1 - Micro-X-ray absorption spectroscopy with compound refractive lenses N2 - A study regarding the possibility to use compound refractive lenses (CRLs) for X-ray absorption spectroscopy (XAS) was conducted. For XAS measurements the energy of the monochromatic incident beam has to be tuned over an energy range which is broader than the energy bandwidth of a CRL. To prove that µ-XAS with compound refractive lenses is possible, it had to be investigated how changes in the energy influence the beam parameters. This was done by tuning the energy around the nominal energy of the lens and recording images with a high resolution X-ray imaging setup. To investigate the changes in the spot size the scintillator was placed at the nominal focal distance and scans along the beam axis were performed. The effect on the photon flux of the incident beam due to absorption in the lens was investigated by performing XANES measurement on different reference materials with and without CRL. The results of these measurements using a CRL designed for 9 keV are shown and discussed. KW - Micro-XAS KW - Compound refractive lens PY - 2012 U6 - https://doi.org/10.1039/c2ja30130j SN - 0267-9477 SN - 1364-5544 VL - 27 IS - 10 SP - 1803 EP - 1808 PB - Royal Society of Chemistry CY - London AN - OPUS4-26790 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Buzanich, Günter A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, Heinrich A1 - Thünemann, Andreas A1 - Streli, C. T1 - Impurities in multicrystalline silicon wafers for solar cells detected by synchrotron micro-beam X-ray fluorescence analysis N2 - We report on the trace analysis of copper and iron impurities in multicrystalline silicon wafers with the microbeam X-ray fluorescence (µ-XRF) technique. The efficiency of solar cells, which are based on multicrystalline silicon wafers, is strongly influenced by minor contamination with metals such as copper and iron. Application of compound refractive lenses (CRLs) in µ-XRF allows versatile two-dimensional mapping of relevant contaminations and localization of their sites of deposition. In this context, the measured bulk average limit of detection (LOD) was one picogram of iron and copper per gram of silicon. We suggest that µ-XRF is a valuable tool for non-destructive spatial (3D) quantification of metal impurities in a wide range of materials and devices whose functioning could be critically affected by impurities. KW - X-ray micro beam KW - Compound refractive lens KW - Solar cell KW - Silicon impurities PY - 2012 U6 - https://doi.org/10.1039/c2ja30188a SN - 0267-9477 SN - 1364-5544 VL - 27 IS - 11 SP - 1875 EP - 1881 PB - Royal Society of Chemistry CY - London AN - OPUS4-26791 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Iro, M. A1 - Ingerle, D. A1 - Radtke, Martin A1 - de Oliveira Guilherme Buzanich, Ana A1 - Kregsamer, P. A1 - Streli, C. T1 - Investigation of polycapillary half lenses for quantitative confocal micro-X-ray fluorescence analysis N2 - The use of polycapillary optics in confocal micro-X-ray fluorescence analysis (CMXRF) enables the destruction-free 3D investigation of the elemental composition of samples. The energy-dependent transmission properties, concerning intensity and spatial beam propagation of three polycapillary half lenses, which are vital for the quantitative interpretation of such CMXRF measurements, are investigated in a monochromatic confocal laboratory setup at the Atominstitut of TU Wien, and a synchrotron setup on the BAMline beamline at the BESSY II Synchrotron, Helmholtz-Zentrum-Berlin. The empirically established results, concerning the intensity of the transmitted beam, are compared with theoretical values calculated with the polycap software package and a newly presented analytical model for the transmission function. The resulting form of the newly modelled energy-dependent transmission function is shown to be in good agreement with Monte Carlo simulated results for the complete energy regime, as well as the empirically established results for the energy regime between 6 keV and 20 keV. An analysis of possible fabrication errors was conducted via pinhole scans showing only minor fabrication errors in two of the investigated polycapillary optics. The energy-dependent focal spot size of the primary polycapillary was investigated in the laboratory via the channel-wise evaluation of knife-edge scans. Experimental results are compared with data given by the manufacturer as well as geometric estimations for the minimal focal spot size. Again, the resulting measurement points show a trend in agreement with geometrically estimated results and manufacturer data. KW - BAMline KW - Synchrotron KW - Capillary KW - confocal PY - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-562430 SN - 1600-5775 VL - 29 SP - 1376 EP - 1384 PB - International Union of Crystallography CY - Chester AN - OPUS4-56243 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Hampel, S. A1 - Fittschen, UEA A1 - Streli, C. A1 - Radtke, Martin T1 - Reconstruction for coded aperture full-field x-ray fluorescence imaging N2 - X-ray fluorescence imaging is a well-established tool in materials characterization. In this work, we present the adaption of coded aperture imaging to full-field X-ray fluorescence imaging at the synchrotron. Coded aperture imaging has its origins in astrophysics, and has several advantages: Coded apertures are relatively easy to fabricate, achromatic, allow a high photon throughput, and high angular acceptance. Coded aperture imaging is a two-step-process, consisting of the measurement process and a reconstruction step. Different programs have been written, for the raytracing/forward projection and the reconstruction. Experiments with coded aperture in combination with a Color X-ray Camera and an energy-dispersive area detector, have been conducted at the BAMline. Measured samples were successfully reconstructed, and gave a 9.1-fold increase in count rate compared to a polycapillary optic. KW - Synchrotron KW - BAMline KW - Coded Aperture PY - 2022 SN - 1097-0002 VL - 65 SP - 57 EP - 70 PB - Cambridge University Press CY - Cambridge AN - OPUS4-56350 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Menzel, M. A1 - Scharf, O. A1 - Novak, S. A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Hischenhuber, P. A1 - Buzanich, Günter A1 - Meyer, A. A1 - Lopez, V. A1 - McIntosh, K. A1 - Streli, C. A1 - Havrilla, G. A1 - Fittschen, U. T1 - Shading in TXRF: calculations and experimental validation using a color X-ray camera N2 - Absorption effects in total reflection X-ray fluorescence (TXRF) analysis are important to consider, especially if external calibration is to be applied. With a color X-ray camera (CXC), that enables spatially and energy resolved XRF analysis, the absorption of the primary beam was directly visualized for mL-droplets and an array of pL-droplets printed on a Si-wafer with drop-on-demand technology. As expected, deposits that are hit by the primary beam first shade subsequent droplets, leading to a diminished XRF signal. This shading effect was quantified with enhanced precision making use of sub-pixel analysis that improves the spatial resolution of the camera. The measured absorption was compared to simulated results using three different model calculations. It was found they match very well (average deviation < 10%). Thus errors in quantification due to absorption effects can be accounted for in a more accurate manner. KW - absorption KW - X-ray Fluorescence analysis PY - 2015 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-359000 IS - 10 SP - 2184 EP - 2193 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-35900 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Sávoly, Z. A1 - Buzanich, Günter A1 - Pepponi, G. A1 - Streli, C. A1 - Hrács, K. A1 - Nagy, P.I. A1 - Záray, G. T1 - The fate of nano-ZnO and its bulk counterpart in the body of microscopic nematodes: an X-ray spectrometric study N2 - The distribution and speciation of zinc were studied in the body of female specimens of the soil-inhabiting, plant-feeding nematode, Xiphinema vuittenezi treated with nano-ZnO and its bulk counterpart. Lyophilized nematodes were studied by X-ray absorption near edge structure spectrometry (XANES) in order to characterize the zinc speciation. Furthermore, in the cross-sections prepared by focused ion beam technique, elemental maps were obtained using the electron probe microanalysis (EPMA) technique. XANES spectra were collected from three different regions (head, midbody and tail region) of nematodes in case of two different treatments (50 mg/L bulk and nano-ZnO suspension, 24 h long treatment). The sample spectra were fitted by the spectra of several reference compounds, the main components of the fitted spectra are the following in all cases: bulk/nano-ZnO; Zn–His and Zn3(PO4)2 * xH2O. Consequently, partial biotransformation takes place for both treatments, histidine- and phosphate-rich ligands play dominant role in the binding of zinc. According to the result of the EPMA analysis, it can be established that the distribution of zinc correlates with the calcium and phosphorus distribution for both treatments. Considering the results of the investigations performed by the two microanalytical techniques, it is likely that calcium phosphate granules were formed in order to bind zinc and hereby to take part in zinc detoxification. Apparent difference in the behavior of bulk and nano-sized ZnO in the body of the investigated nematodes was not found. KW - Nematode KW - Elemental distribution KW - X-ray absorption near edge structure (XANES) KW - ZnO nanoparticles KW - Zinc detoxification PY - 2015 U6 - https://doi.org/10.1016/j.microc.2014.08.011 SN - 0026-265x VL - 118 SP - 80 EP - 87 PB - Elsevier B.V. CY - Amsterdam [u.a.] AN - OPUS4-31632 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fittschen, U. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Böttger, S. A1 - Rosenberg, D. A1 - Menzel, M. A1 - Jensen, W. A1 - Busker, M. A1 - Gotlib, Z. A1 - Radtke, Martin A1 - Riesemeier, Heinrich A1 - Wobrauschek, P. A1 - Streli, C. ED - de Oliveira Guilherme Buzanich, Ana T1 - A setup for synchrotron-radiation-induced total reflection X-ray fluorescence and X-ray absorption near-edge structure recently commissioned at BESSY II BAMline N2 - An automatic sample changer chamber for total reflection X-ray fluorescence (TXRF) and X-ray absorption near-edge structure (XANES) analysis in TXRF geometry was successfully set up at the BAMline at BESSY II. TXRF and TXRF-XANES are valuable tools for elemental determination and speciation, especially where sample amounts are limited (<1 mg) and concentrations are low (ng ml⁻¹ to μg ml⁻¹). TXRF requires a well defined geometry regarding the reflecting surface of a sample carrier and the synchrotron beam. The newly installed chamber allows for reliable sample positioning, remote sample changing and evacuation of the fluorescence beam path. The chamber was successfully used showing accurate determination of elemental amounts in the certified reference material NISTwater 1640. Low limits of detection of less than 100 fg absolute (10 pg ml⁻¹) for Ni were found. TXRF-XANES on different Re species was applied. An unknown species of Re was found to be Re in the +7 oxidation state. KW - TXRF KW - TXRF-XANES KW - Sample changer KW - BAMline KW - Re-XANES PY - 2016 U6 - https://doi.org/10.1107/S1600577516001995 SN - 1600-5775 VL - 23 IS - 3 SP - 820 EP - 824 PB - International Union of Crystallography AN - OPUS4-38656 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Fittschen, U.E.A. A1 - Menzel, M. A1 - Scharf, O. A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Buzanich, Günter A1 - Lopez, V.M. A1 - McIntosh, K. A1 - Streli, C. A1 - Havrilla, G.J. T1 - Observation of X-ray shadings in synchrotron radiation-total reflection X-ray fluorescence using a color X-ray camera N2 - Absorption effects and the impact of specimen shape on TXRF analysis has been discussed intensively. Model calculations indicated that ring shaped specimens should give better results in terms of higher counts per mass signals than filled rectangle or circle shaped specimens. One major reason for the difference in signal is shading effects. Full field micro-XRF with a color X-ray camera (CXC) was used to investigate shading, which occurs when working with small angles of excitation as in TXRF. The device allows monitoring the illuminated parts of the sample and the shaded parts at the same time. It is expected that sample material hit first by the primary beam shade material behind it. Using the CXC shading could be directly visualized for the high concentration specimens. In order to compare the experimental results with calculation of the shading effect the generation of controlled specimens is crucial. This was achieved by 'drop on demand' technology. It allows generating uniform, microscopic deposits of elements. The experimentally measured shadings match well with those expected from calculation. KW - TXRF KW - Full field micro-XRF KW - Color X-ray camera PY - 2014 U6 - https://doi.org/10.1016/j.sab.2014.06.025 SN - 0584-8547 SN - 0038-6987 VL - 99 SP - 179 EP - 184 PB - Elsevier CY - Amsterdam AN - OPUS4-31180 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Streli, C. A1 - Radtke, Martin T1 - On the way to full-field X-ray fluorescence spectroscopy imaging with coded apertures N2 - Imaging with X-rays is a challenging field, due to the optical properties of X-rays. The fabrication of appropriate optics is usually expensive and requires an elaborate manufacturing process. One simpler and less expensive possibility of imaging high energy radiation is coded aperture imaging, a technique well established in astrophysics and also used in nuclear medicine or radiation detection, e.g., for nuclear decommissioning. Our aim is to adapt coded aperture imaging for X-ray fluorescence spectroscopy in the nearfield. In this work we show theoretical considerations and preliminary simulations of Image formation through a coded aperture and three different reconstruction methods to prepare the experiments. We used a new mask based on an inverted modified uniformly redundant array (MURA) that could be used for the construction of a decoding mask for all investigated geometrical arrangements. The most commonly used reconstruction method, convoluting the detected image with a Decoding mask, does not always deliver satisfactory results. This is more noticeable for small distances between the object, mask and detector. Hence, we developed two new reconstruction methods, one based on iterative algebraic optimization and another one based on a genetic algorithm. Both show good performance even in those cases where the convolution method fails. This provides a basis for further investigations of the ideal parameters for near field coded aperture imaging and refinements of the algorithms. We performed first measurements with a coded aperture at the BAMline at BESSY II and could successfully reconstruct a test object from the obtained recorded images. KW - X-ray fluorescence spectroscopy KW - Coded aperture KW - Imaging KW - Iterative reconstruction PY - 2020 U6 - https://doi.org/10.1039/c9ja00232d VL - 35 IS - 2 SP - 347 EP - 356 PB - Royal Society of Chemistry CY - Cambridge AN - OPUS4-50459 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - de Oliveira Guilherme Buzanich, Ana A1 - Reinholz, Uwe A1 - Emmerling, Franziska A1 - Hampel, S. A1 - Fittschen, U.E.A. A1 - Streli, C. A1 - Radtke, Martin T1 - Comparison of three reconstruction methods based on deconvolution, iterative algorithm and neural network for X-ray fluorescence imaging with coded apertures N2 - X-ray imaging methods are used in many fields of research, as they allow a non-destructive Investigation of the elemental content of various samples. As for every imaging method, for X-ray imaging the optics are of crucial importance. However, these optics can be very expensive and laborious to build, as the requirements on surface roughness and precision are extremely high. Angles of reflection and refraction are often in the range of a few mrad, making a compact design hard to achieve. In this work we present a possibility to simplify X-ray imaging. We have adapted the coded aperture method, a high energy radiation imaging method that has its origins in astrophysics, to full field X-ray fluorescence imaging. In coded aperture imaging, an object is projected through a known mask, the coded aperture, onto an area sensitive detector. The resulting image consists of overlapping projections of the object and a reconstruction step is necessary to obtain the information from the recorded image. We recorded fluorescence images of different samples with an energy-dispersive 2D detector (pnCCD) and investigated different reconstruction methods. With a small coded aperture with 12 holes we could significantly increase the count rate compared to measurements with a straight polycapillary optic. We show that the reconstruction of two different samples is possible with a deconvolution approach, an iterative algorithm and a neural network. These results demonstrate that X-ray fluorescence imaging with coded apertures has the potential to deliver good results without scanning and with an improved count rate, so that measurement times can be shortened compared to established methods. KW - X-ray fluorescence imaging KW - Coded apertures KW - Imaging KW - Elemental mapping KW - Image reconstruction PY - 2020 U6 - https://doi.org/10.1039/d0ja00146e VL - 35 IS - 7 SP - 1423 EP - 1434 PB - Royal Society of Chemistry CY - United Kingdom AN - OPUS4-51518 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Rauwolf, M. A1 - Turyanskaya, A. A1 - Roschger, A. A1 - Prost, J. A1 - Simon, R. A1 - Scharf, O. A1 - Radtke, Martin A1 - Schoonjans, Tom A1 - de Oliveira Guilherme Buzanich, Ana A1 - Klaushofer, K. A1 - Wobrauschek, P. A1 - Hofstaetter, J. G. A1 - Roschger, P. A1 - Streli, C. T1 - Synchrotron radiation micro X-ray fluorescence spectroscopy of thin structures in bone samples: comparison of confocal and color X-ray camera setups N2 - In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-mXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its K alpha XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution. KW - Synchrotron KW - BAMline KW - BESSY KW - XRF KW - X-ray Color Camera PY - 2017 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:b43-391944 SN - 1600-5775 VL - 24 SP - 307 EP - 311 PB - International Union of Crystallography AN - OPUS4-39194 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Kulow, Anicó A1 - Witte, S. A1 - Beyer, S. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin A1 - Reinholz, Uwe A1 - Riesemeier, H. A1 - Streli, C. T1 - A new experimental setup for time- and laterally-resolved X-ray absorption fine structure spectroscopy in a 'single shot' N2 - In this work, a new setup for dispersive XAFS measurements is presented. This reproducible and scanningfree setup yields both time- and laterally-resolved XAFS experiments in a ‘single-shot’. It allows a straightforward adjustment for probing different elements covering many relevant applications in materials science. An incoming energetic broadband beam is diffracted by a Si (111) crystal after passing through the sample and collected by an area sensitive detector. Depending on the energy range of the incoming beam, XANES and/or EXAFS spectra can be recorded with a time resolution down to 1 s. The feasibility of this setup was demonstrated at the BAMline at BESSY II (Berlin, Germany) with reference Fe and Cu foils and the results are hereby presented and discussed. Additionally, an application where time resolution on the second scale is required is briefly evaluated. The presented example concerns studying early stages of zinc(II)2-methylimidazolate (ZIF-8) crystallization. This is particularly important for biomedical applications. KW - X-ray spectroscopy KW - X-ray absorption fine structure KW - Time-resolved KW - Laterally-resolved KW - Experimental setup PY - 2019 U6 - https://doi.org/10.1039/c8ja00313k SN - 0267-9477 SN - 1364-5544 VL - 34 IS - 1 SP - 239 EP - 246 PB - Royal Society of Chemistry CY - London AN - OPUS4-47207 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Cakir, Cafer Tufan A1 - Piotrowiak, T. A1 - Reinholz, Uwe A1 - Ludwig, A. A1 - Emmerling, Franziska A1 - Streli, C. A1 - de Oliveira Guilherme Buzanich, Ana A1 - Radtke, Martin T1 - Exploring the Depths of Corrosion: A Novel GE-XANES Technique for Investigating Compositionally Complex Alloys N2 - In this study, we propose the use of nondestructive, depth-resolved, element-specific characterization using grazing exit X-ray absorption near-edge structure spectroscopy (GE-XANES) to investigate the corrosion process in compositionally complex alloys (CCAs). By combining grazing exit X-ray fluorescence spectroscopy (GE-XRF) geometry and a pnCCD detector, we provide a scanning-free, nondestructive, depth-resolved analysis in a sub-micrometer depth range, which is especially relevant for layered materials, such as corroded CCAs. Our setup allows for spatial and energy-resolved measurements and directly extracts the desired fluorescence line, free from scattering events and other overlapping lines. We demonstrate the potential of our approach on a compositionally complex CrCoNi alloy and a layered reference sample with known composition and specific layer thickness. Our findings indicate that this new GE-XANES approach has exciting opportunities for studying surface catalysis and corrosion processes in real-world materials. KW - Degradation mechanisms KW - Grazin exit XANES KW - Depth resolved XANES KW - Compositional complex alloys KW - Corrosion PY - 2023 U6 - https://doi.org/10.1021/acs.analchem.3c00404 VL - 95 SP - 4810 EP - 4818 PB - ACS Publications AN - OPUS4-57823 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -