Filtern
Erscheinungsjahr
Dokumenttyp
- Zeitschriftenartikel (9)
- Posterpräsentation (5)
- Vortrag (3)
- Buchkapitel (2)
- Beitrag zu einem Sammelband (1)
Sprache
- Englisch (20)
Schlagworte
- X-ray fluorescence (20) (entfernen)
Organisationseinheit der BAM
Eingeladener Vortrag
- nein (3)
Compact pnCCD-based X-ray camera with high spatial and energy resolution: a color X-ray camera
(2011)
For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called 'color X-ray camera' (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 µm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69696 spectra with an energy resolution of 152 eV for manganese Kα with a spatial resolution of 50 µm over an imaging area of 12.7 × 12.7 mm². It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 µm beryllium window, and the sensitive thickness of 450 µm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.
Synchrotron radiation induced X-ray fluorescence for the characterization of ancient gold objects
(2009)
Fingerprinting ancient gold work requires the use of nondestructive techniques with high spatial resolution (down to 25 µm) and good detection limits (micrograms per gram level). In this work experimental setups and protocols for synchrotron radiation induced X-ray fluorescence (SRXRF) at the BAMline of the Berlin electron storage ring company for synchrotron radiation (BESSY) in Berlin for the measurement of characteristic trace elements of gold are compared considering the difficulties, shown in previous works, connected to the quantification of Pt. The best experimental conditions and calculation methods were achieved by using an excitation energy of 11.58 keV, a silicon drift chamber detector (SDD) detector, and pure element reference standards. A detection limit of 3 µg/g has been reached. This newly developed method was successfully applied to provenancing the Xiongnu gold from the Gol Mod necropolis, excavated under the aegis of the United Nations Educational, Scientific and Cultural Organization (UNESCO). The composition of the base alloys and the presence of Pt and Sn showed that, contrary to what is expected, the gold foils from the first powerful empire of the steppes along the Great Wall were produced with alluvial gold from local placer deposits located in Zaamar, Boroo, and in the Selenga River.
News from the BAMline
(2022)
Getting more efficient – The use of Bayesian optimization and Gaussian processes at the BAMline
(2022)
For more than 20 years, BAM is operating the BAMline at the synchrotron BESSY II in Berlin Adlershof. During this time, the complexity of the setup and the amount of data generated have multiplied. To increase the effectiveness and in preparation for BESSY III, algorithms from the field of machine learning are increasingly used.
After a short introduction to BO and GP, the first example is the automatic alignment of our double multilayer monochromator (DMM).
The second example is the optimization of measurement time in XRF scanning.
A microfocus X-ray source mounted on the analysis chamber of an SEM was used to excite X-ray fluorescence spectra and to detect chemical elements with concentrations below the detection limit of the electron-excited X-ray spectra conventionally measured with SEM/EDS. An aluminium alloy and a hard material ceramics were analysed as representative examples. It is demonstrated that the combination of the three analytical methods: (1) SEM imaging for surface morphology characterisation; (2) electron-excited X-ray spectroscopy with its high spatial resolution for element analysis of inclusions or precipitates; and (3) X-ray fluorescence for the detection of elements with concentrations below 0.1 mass% considerably improves the performance of SEM/EDX analyses.
The Federal Institute for materials research and testing (BAM)in cooperation with the Fachhochschule Münster has developed a new certified polymeric reference material, BAM-H010. The reference material consists of acrylonitrile–butadiene–styrene terpolymer (ABS) and has been doped with different contents of the elements Br, Cd, Cr, Hg and Pb. The monitoring of these elements is demanded in the EU directive 2002/95/EG, commonly referred to as RoHS. We have shown that the uncertainty contribution of the thermal long-term stability (ustability) is negligible compared to the contribution to the uncertainty caused by the method used for the characterization of the elemental content and the batch inhomogeneity (uhomogeneity). The stability of theABS material during exposure of the samples with hard X-radiation leads to a degradation of the ABS matrix with either long- or short-chain products.
Statistic process control as well as process capability demand for calibrated determination of layer thicknesses in various industries, e.g. automotive, aerospace, microelectronics manufacturing. Calibration requires well know and well characterized samples. A calibration laboratory accredited according to DIN EN ISO 17025 has the objective to distribute standards traceable to SI units to industrial laboratories for quality control of manufacturing of various products. Especially, the thickness determination of thin metallic coatings e.g. from galvanic processes or layer deposition using X-Ray Fluorescence can be significantly improved by customized calibration samples. This is essential as the measurement uncertainty directly correlates to the capability performing reliable control of processes with high yield. For calibration laboratories, the validation of results using round robins and the direct comparison to national metrology institutes is a prerequisite to demonstrate the competence to perform calibration services.
In this paper a strategy to obtain traceability and validation for thin alloy layers as well as first results are presented. The combined use of the accredited method for determination of mass per area from measurement of mass and area combined with standard free X-Ray Fluorescence as well as chemical analysis of dissolved samples with thin layers is deployed for material systems as NixZn1-x as well as NixP1-x. The obtained results are compared to reference free X-Ray Fluorescence at the BESSY II laboratories of Physikalisch-Technische Bundesanstalt. An excellent agreement of the obtained measured values as mass per unit area and alloy concentrations from the different applied methods within the measurement uncertainty was observed for NixP1-x showing the successful performed traceability of the calibration samples to SI units in combination with a validation of results by national metrology institutes and the round robin approach.
New developments in spectroscopic techniques for process control are, in general, driven by shortcomings of existing technology, for example, when sensitivity, selectivity, robustness, and so forth do not meet the demands. The perfect process analytical method would be based on a robust and easy to handle customized technique operating in real time, come without any need for calibration, that is, be an absolute method, have a professional support, and be compliant to increasing regulatory requirements. However, there are at least trends toward such an all-in-one device suitable for every purpose.
Small, low-field NMR systems equipped with permanent magnet technology have been developed and allow for quantitative analysis as on-line instruments in a production environment. Quantitative high-resolution on-line NMR spectroscopy contributes to process understanding in pilot plant and research environments.
Laser spectroscopy is a promising field in process analysis owing to its sensitivity and selectivity. Laser-induced breakdown spectroscopy LIBS is a promising field for direct in situ analysis and remote sensing. Applications of quantum-cascade lasers for process analytical applications are a promising technique. Techniques such as cavity ring-down spectroscopy (CRDS), tunable diode laser absorption spectroscopy (TDLAS), and photothermal techniques are briefly introduced.
Recent developments of new detectors have improved X-ray fluorescence analysis (XRF) for qualitative and quantitative on-line evaluation of the elementary composition of liquid or solid samples, regardless of whether compact or bulk material.
The chapter also introduces miscellaneous techniques such as ion mobility spectroscopy (IMS), microwave and dielectric spectroscopy, terahertz spectroscopy, ultrasonic acoustic spectroscopy, and other methods.
Our aim is to develop a new method for full field X ray fluorescence imaging at the BAM line @ BESSY II. We will combine an energydispersive array detector for X rays with a coded aperture to get high resolution images . In coded aperture imaging , an object is projected through a mask , producing many overlapping images on the detector . The first part of the project is to perform raytracing simulations to get realistic data and to develop a reconstruction method that allows to get the Information about the investigated object out of the projected image .