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Eingeladener Vortrag
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A combination of 3D micro X-ray fluorescence spectroscopy (3D micro-XRF) and micro-XRF was utilized for the investigation of a small collection of highly heterogeneous, partly degraded Dead Sea Scroll parchment samples from known excavation sites. The quantitative combination of the two techniques proves to be suitable for the identification of reliable marker elements which may be used for classification and provenance studies. With 3D micro-XRF, the three-dimensional nature, i.e. the depth-resolved elemental composition as well as density variations, of the samples was investigated and bromine could be identified as a suitable marker element. It is shown through a comparison of quantitative and semiquantitative values for the bromine content derived using both techniques that, for elements which are homogeneously distributed in the sample matrix, quantification with micro-XRF using a one-layer model is feasible. Thus, the possibility for routine provenance studies using portable micro-XRF instrumentation on a vast amount of samples, even on site, is obtained through this work.
In this work, the applicability of a new 3D micro X-ray fluorescence (3D Micro-XRF) laboratory spectrometer for the investigation of historical glass objects is demonstrated. The non-destructiveness of the technique and the possibility to measure three-dimensionally resolved fluorescence renders this technique into a suitable tool for the analysis of cultural heritage objects. Although absorption and resolution effects complicate qualitative analysis of the data, layered structures can be distinguished from homogeneous samples without the need for full quantification. Different manufacturing techniques were studied in this work with the help of hand-made reference samples. With the gained knowledge it could be shown for the investigated historical glass object, that black enamel as a stained glass contour colour was used in a cold painting. The object was not fired after the application of the black enamel, but instead the adhesion of the paint was solely provided through organic binding agents and the backing with metal foils. Thus, for the manufacturing of the object, a mixture of cold painting technique with a stained glass color was used. Quantitative measurements with a 3D Micro-XRF setup at the Berlin synchrotron BESSY II confirm the assumptions drawn on the basis of the qualitative investigation with the 3D Micro-XRF spectrometer with X-ray tube excitation.
Nowadays, micro-x-ray fluorescence analysis has become an established tool for the non-destructive investigation of art objects. However, as these types of sample often forms complex and inhomogeneous layer systems, the quantitative evaluation of the measurements is far from a standard routine. In this paper a fingerprint model is described, which we developed to discriminate between different iron-gall inks of historical manuscripts or compositions. Fundamental parameter methods are used to take self-attenuation, interference from the paper background and diffusion of the ink into the paper into account. The capability of the method to contribute to the solution of archaeometric problems is exemplified by the investigation of an ancient composition. Finally, the restrictions of the model and possible improvements are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Nowadays, micro-x-ray fluorescence analysis has become an established tool for the non-destructive investigation of art objects. However, as these types of sample often forms complex and inhomogeneous layer systems, the quantitative evaluation of the measurements is far from a standard routine. In this paper a fingerprint model is described, which we developed to discriminate between different iron-gall inks of historical manuscripts or compositions. Fundamental parameter methods are used to take self-attenuation, interference from the paper background and diffusion of the ink into the paper into account. The capability of the method to contribute to the solution of archaeometric problems is exemplified by the investigation of an ancient composition. Finally, the restrictions of the model and possible improvements are discussed. Copyright © 2004 John Wiley & Sons, Ltd.
A new fundamental parameter based calibration procedure for micro X-ray fluorescence spectrometers
(2011)
Fundamental parameter based quantification of X-ray fluorescence (XRF) measurement data requires an accurate knowledge of the spectrometer parameters, including the spectral distribution of the excitation radiation. In case of micro-XRF where a polycapillary optic is utilized in the excitation channel this distribution is changed due to the transmission properties of the lens. A new calibration procedure, based on fluorescence data of thin standard samples, was developed to determine the excitation spectrum, i.e., the product of the X-ray tube spectrum and the transmission of the used X-ray optic of a micro-XRF setup. The calibration result was validated by the quantitative analyses of certified multi-element reference standards and shows uncertainties in the order of 2% for main components, 10% for minor elements and 25% for trace elements. The influence of secondary order effects like Coster–Kronig transitions and cascade effects is analyzed and the accuracy of fundamental parameters in common databases is discussed.
The qualitative and quantitative investigation of historical iron-gall inks using micro-XRF spectrometry is a suitable method for analyzing composition fingerprints of different ink types. The quantitative analysis is based on a model that takes into account the inhomogeneity and the layer structure of archaeometric samples. Starting from these composition fingerprints, it is possible to characterize distinguishable inks of one artist to classify different chronological ink types and, further, to date unknown fragments that have not so far been integrated into the lifework of an artist. The first qualitative and quantitative investigations of the manuscript Faust I and II and of the music composition The Magic Flute demonstrate impressively the identification of J. W. v. Goethe's and W. A. Mozart's artistic work with modern scientific methods. Further investigations on A. v. Arnim's manuscript Studien zu Naturwissenschaften provide evidence that the diversity of various degradation mechanisms of iron-gall inks could be mainly caused by different inorganic compositions.
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.