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Strahlenverfahren in Kombination - ein Werkzeug für Analyse und Zertifizierung von Feststoffen
(2002)
A layer of Sb atoms, implanted with an energy of 400 keV and a nominal dose of 5×1016 atoms/cm2 into a high purity silicon wafer, was certified for its areal density (atoms/cm2) using Rutherford backscattering spectrometry (RBS), instrumental neutron activation analysis (INAA) and inductively coupled plasma isotope dilution mass spectrometry (ICP-IDMS) and for its isotope ratio using INAA and ICP-IDMS. Excellent agreement between the results of the different independent methods was found. In the present work, the measurements of the homogeneity of the areal density of Sb, previously determined with RBS in spots having 1 mm diameter, are improved with synchrotron X-ray fluorescence analysis: Higher precision in even smaller sample spots allows to estimate a reduced inhomogeneity of the whole batch of samples of the order of only 0.4%. Thus the uncertainty of the certified value can further be reduced. Down to fractions of a chip with 0.3×0.4 mm2 area, the areal density is now certified as (4.81±0.06)×1016 Sb atoms/cm2, where the expanded uncertainty 0.06 (coverage factor k=2) corresponds to only 1.2%. The relative merits of the different analytical methods are discussed.
Electron probe microanalysis (EPMA) measurement of thin-film thickness in the nanometre range
(2002)
The thickness of thin films of platinum and nickel on fused silica and silicon substrates has been determined by EPMA using the commercial software STRATAGEM for calculation of film thickness. Film thickness ranged in the order 10 nm. An attempt was made to estimate the confidence range of the method by comparison with results from other methods of analysis. The data show that in addition to the uncertainty of the spectral intensity measurement and the complicated fitting routine, systematic deviation caused by the underlying model should be added. The scattering in the results from other methods does not enable specification of a range of uncertainty, but deviations from the real thickness are estimated to be less than 20%.
This Report describes the certification of the reference material antimony implanted in Si/SiO2 intended to be used for calibration of surface and near surface analytical methods. It describes the preparation, homogeneity measurements and the analytical work performed for the certification of both Areal density of antimony Atoms (retained dose) and the isotope amount Ratio as well as giving considerations on the stability of the material.
Pilot studies have been carried out at the BAMline at BESSY II in collaboration with the Bundesanstalt
für Materialforschung und -prüfung (BAM) on metal- and metalloid-containing compounds in biological
samples after electrophoretic protein separation. After sodium dodecylsulfate polyacrylamide gel
electrophoresis (SDS-PAGE) and transfer onto a blotting membrane the distribution of selenium among
the proteins of testis homogenate of a rat and a wallaby was determined. The comparison with the
autoradiogram of 75Se-labeled proteins separated in the same way showed that of nine seleniumcontaining
proteins found in rat testis homogenate by autoradiography four could be detected by
synchrotron radiation X-ray fluorescence analysis (SRXRF).
Orientierende Versuche zur Schwefelbestimmung in Kraftstoffen haben gezeigt, dass die Röntgenbeamline der BAM bei BESSY II geeignet ist, Schwefel auch in kleinen Konzentrationen zu bestimmen. Da das Verfahren der synchrotronstrahlungsinduzierten Röntgenfluoreszenzanalyse (SYRFA) für den Vor-Ort-Einsatz nicht geeignet ist, ist das Ziel der Untersuchungen, durch Variation von Anregungsenergie und -geometrie mögliche Quellen für systematische Fehler zu untersuchen. Durch geeignete Korrekturfaktoren kann dann die Richtigkeit der Analyseergebnisse gewährleistet werden. Das Verfahren soll dann als Alternative bzw. Ergänzung zu zerstörenden Verfahren der Schwefelanalyse Anwendung finden. Damit wird ein Beitrag zur künftigen Herstellung zertifizierter Referenzmaterialien (ZRM) geleistet.
Naturwissenschaftliche Informationen, insbesondere die chemische Zusammensetzung der Objekte, können Hinweise auf die Hintergründe der Objektherstellung liefern, die der alleinigen kunsthistorischen Begutachtung verborgen blieben. Es können nicht nur Fragen nach dem Prozess, Zeitpunkt und Ort der Herstellung beantwortet werden. Die chemische Analyse gibt auch Hinweise auf Ereignisse und Veränderungen, die erst nach der Fertigstellung des Objektes erfolgten. So werden Alterungsphänomene oder historische Überarbeitungen und Restaurierungen aufgedeckt, aber auch Konservierungsstrategien zur Erhaltung der Kunstwerke unterstützt. Durch den technologischen Fortschritt im Bereich der röntgenanalytischen Methoden, die berührungsfrei, ohne Probennahme und ohne Schädigung für das Untersuchungsobjekt arbeiten, erschließen sich dem Analytiker erstmalig Möglichkeiten, auch sehr wertvolle und fragile Objekte zerstörungsfrei zu untersuchen.
3D micro X-ray fluorescence spectroscopy - combining elemental analysis with chemical speciation
(2004)
Spatially resolved X-ray fluorescence analysis using synchrotron radiation (SR-XRF) at the wavelength shifter beamline, BAMline, at BESSY was used to investigate Renaissance silverpoint drawings as it is extremely sensitive, non-destructive and can be carried out in air using an excitation spot in the hundred micrometer range.
This paper deals with first results of the study of silverpoint drawings of Albrecht Dürer (14711528) belonging to the sketchbook that Albrecht Dürer used during a travel to the Netherlands in 1520/21. These results are compared to a PIXE study performed on drawings from the same sketchbook.
The minor element composition of the silverpoint used for the drawings in the sketchbook was (10.6 ± 3.5) wt.% of Cu and traces of Zn. Mercury was found in the marks but does not belong to the initial composition of the silverpoint as it is attributed to an alteration phenomenon. One drawing of the sketchbook represents an exception. It consists of silver marks containing an additional minor element, Zn, in the marks and was, therefore, created with another silverpoint, probably at a different time than the other drawings.
Synchrotron-induced X-ray fluorescence (Sy-XRF) analysis was used to study the chemical composition of precious Renaissance silverpoint drawings. Drawings by famous artists such as Albrecht Dürer (14711528) and Jan van Eyck (approximately 13951441) must be investigated non-destructively. Moreover, extremely sensitive synchrotron- or accelerator-based techniques are needed since only small quantities of silver are deposited on the paper. New criteria for attributing these works to a particular artist could be established based on the analysis of the chemical composition of the metal points used. We illustrate how analysis can give new art historical information by means of two case studies. Two particular drawings, one of Albrecht Dürer, showing a profile portrait of his closest friend, Willibald Pirckheimer (1503), and a second one attributed to Jan van Eyck, showing a Portrait of an elderly man, often named Niccolò Albergati, are the object of intense art historical controversy. Both drawings show inscriptions next to the figures. Analyses by Sy-XRF could reveal the same kind of silverpoint for the Pirckheimer portrait and its mysterious Greek inscription, contrary to the drawing by Van Eyck where at least three different metal points were applied. Two different types of silver marks were found in this portrait. Silver containing gold marks were detected in the inscriptions and over-subscriptions. This is the first evidence of the use of gold points for metal point drawings in the Middle Ages.
Vultures hit by beam
(2005)
The first hard x-ray beamline at BESSY II has been installed by BAM and PTB at a superconducting 7 T wavelength shifter. The main optical elements of the beamline are a double-multilayer monochromator and a double-crystal monochromator. Depending on the application, the two devices are used separately or in-line. The main applications of the monochromatic radiation with photon energies up to 60 keV are x-ray fluorescence analysis, micro computed tomography, x-ray topography, detector calibration and reflectometry. Calculable undispersed radiation up to 200 keV is available for radiometric applications.
Synchrotron radiation (SR) has been used in recent years as an excellent excitation source for X-ray fluorescence spectrometry. SR offers, in contrast to conventional X-ray sources, highly brilliant polychromatic, polarized radiation with which micro-domain X-ray fluorescence spectrometry becomes possible. A feasibility study of utility, conducted at BESSY (Berlin) and at DELTA (Dortmund), both synchrotron facilities of the third generation, to evaluate the use of wavelength dispersive X-ray fluorescence spectrometry in combination with synchrotron radiation is presented. First results for material analysis, obtained by combining the synchrotron radiation and a commercially available spectrometer commonly attached to a scanning electron microscope, are presented. The spectrometer, of the linear type, uses curved focusing Bragg-crystals of the Johann type which leads to a high spectral resolution up to 3 eV. Examples of micro-domain analyses are presented and compared with those obtained by synchrotron radiation induced energy dispersive X-ray fluorescence.
Trace elements of ancient gold such as Pt, give fundamental information on the circulation of the metal in the past. In the case of objects from the cultural heritage, the determination of trace elements requires non-destructive point analysis in general. These conditions and the need of good detection limits restrain the number of applicable analytical techniques.
After the development of a PIXE set-up with a selective Cu or Zn filter of 75 µm and of a PIXE-XRF set-up using a primary target of As, we tested the possibilities of spatially resolved Sy-XRF to determine Pt in gold alloys. With a Zn filter, PIXE showed a detection limit of 1000 ppm in gold while PIXE-XRF lowers this detection limit down to 80 ppm. This last value being constrained by the resonant Raman effect produced on gold. In order to improve the detection limit of Pt keeping the non-destructiveness and access to point analysis, we developed an analytical protocol for XRF with synchrotron radiation at BESSY II, using the BAMline set-up. The L-lines of Pt were excited by a beam of energy above and below 11.564 keV and measured using a Si(Li) detector with a 50 µm Cu filter. A µ-beam of 100250 µm2 was used according to the size of the sample. The determination of the Pt content in the samples was carried out by Monte-Carlo simulation and subtraction of Au and Pt spectra obtained on pure standards. The limit of detection for Pt of 20 ppm was determined by using certified standards. The detection limits of a small set of other characteristic elements of gold were also measured using an incident energy of 33 keV.
Naturwissenschaftler arbeiten mit Archäologen, Kunsthistorikern und Restauratoren zusammen, um Materialinformationen über Kunstwerke mit den Erkenntnissen aus Altertumsforschung, Kunstgeschichte und Denkmalpflege zu verbinden. Röntgenfluoreszenz und Röntgenemission sind die Methoden der Wahl, wenn wertvolle und fragile Objekte zerstörungsfrei zu untersuchen sind.
New analyses of a series of very rare silverpoint drawings that were executed by Rembrandt Harmensz. van Rijn (16061669) which are kept today in the Kupferstichkabinett (Museum of Prints and Drawings) of the State Museums of Berlin are reported here. Analysis of these drawings requires particular attention because the study has to be fully non-destructive and extremely sensitive. The metal alloy on the paper does not exceed some hundreds of µg/cm². Therefore, synchrotron radiation induced X-ray fluorescence (SR-XRF) is together with external micro-proton-induced X-ray emission the only well-suited method for the analyses of metalpoint drawings. In some primary work, about 25 German and Flemish metalpoint drawings were investigated using spatially resolved SR-XRF analysis at the BAMline at BESSY. This study enlarges the existing FrenchGerman database of metalpoint drawings dating from the 15th and 16th centuries, as these Rembrandt drawings originate from the 17th century where this graphical technique was even rarer and already obsolete. It also illustrates how SR-XRF analysis can reinforce art historical assumptions on the dating of drawings and their connection.
We performed spatially resolved synchrotron-induced x-ray fluorescence analyses (SY-XRF) of five silverpoint drawings from the famous `Karlsruhe sketchbook´ and a silverpoint, which is assumed to be an original one used by the Renaissance artist Hans Baldung Grien (1484-1545) himself. The silverpoint, one out of a very small number of ancient styli conserved nowadays, is fixed on the so-called `Karlsruhe sketchbook´. Measurements were executed at the FLUO-TOPO beamline at the electron storage ring ANKA. It has been shown, that SY-XRF at this beamline is nondestructive and sensitive enough for the analysis of minor and major elements in the silver strokes. This study provides new insights into this graphical technique and ancient drawing instruments: results are that three drawings have been created with a common type of silverpoint containing about (10.4 ± 0.7) wt% of Cu. In all the cases, Hg at a 10% level by weight was identified in the strokes. Presence of Hg is not due to the original silver alloy, but is a result of a general alteration phenomenon of silverpoint drawings. This fact is confirmed by the analysis of the original silverpoint, which contains only small traces of Hg. The result for the copper content of the silverpoint (10.4 ± 1.7) wt% is in good agreement with that of these three drawings. It is supposable that the silverpoint found attached today served for the creation of the corresponding drawings. Moreover, the graphical technique of Baldung is found to be continual over three decades. Only one very late drawing dated to 1543 was probably realized with another silverpoint, containing about 3 wt% of Cu. This difference in the chemical composition of drawings from the late period might be used as a more precise dating indicator of Baldung drawings that are not clearly attributed to a certain period.