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Eingeladener Vortrag
- nein (8)
Zerstörungsfreie Mikro-Röntgenluoreszenzanalyse von historischen Schreib- und Zeichenmaterialien
(2005)
Wer schrieb was? Röntgenfluoreszenzanalyse am Autograph von J.S. Bachs Messe in h-Moll BWV 232
(2009)
The Erfurt Hebrew Giant Bible and the Experimental XRF Analysis of Ink and Plummet Composition
(2007)
The aim of the research project 'Typology of
Dutch Drawing' was to establish an interdisciplinary approach
for investigating heterogeneous drawing collections.
To define a type common to a group of drawings, we
determine elements that are common to them based on style
and the use of identical materials. To that end, we investigated
about 750 Dutch drawings from the sixteenth century at the
Dresden Kupferstich-Kabinett using art historical and
scientific methods. In this work, we present a detailed
analysis of 30 drawings ascribed to the Egmont Master.
Die Röntgenfluoreszenzanalyse (RFA) ist ein Standardverfahren in der zerstörungsfreien Elementanalyse. Die Entwicklung von Polykapillaroptiken und von SDD-Halbleiterdetektoren, die ohne Stickstoff-Kühlung auskommen, ermöglicht eine breite Anwendung dieses Verfahrens z. B. in der Kunst- und Kulturgutanalyse. Die dafür entwickelten Spektrometer sind mobil und bieten die Möglichkeit der Analyse von kleinen Strukturen, da Untersuchungs- flächen mit Durchmessern von 10-70 ¹m erzeugt werden. Für quantitative RFA-Ergebnisse werden in den meisten Anwendungsfällen referenzprobenbasierte Auswertungsverfahren eingesetzt. Aufgrund von Absorptionsprozessen in der Probenmatrix ist die Genauigkeit und Verlässlichkeit der ermittelten Konzentrationen dabei stark von der Ähnlichkeit von Referenz- und Untersuchungsprobe abhängig. Liegen keine geeigneten Referenzmaterialien vor, stellt die „Fundamental Parameter (FP) Methode“ eine Alternative dar. Dabei werden die bei der Erzeugung und Detektion auftretenden Wechselwirkungen mit Hilfe geeigneter Datenbanken mathematisch beschrieben. In einem Iterationsverfahren können auf diese Weise die Elementkonzentrationen ermittelt werden. Voraussetzung ist eine genaue Kenntnis der Spektrometerparameter, u. a. der spektralen Verteilung der Anregungsstrahlung. Da durch die Transmissionseigenschaften der Polykapillaroptiken die gut beschriebenen Röntgenröhrenspektren erheblich verändert werden, war eine Anwendung der FP-Methode für die Mikro-RFA bisher nicht möglich. Ziel dieser Arbeit ist es, die Transmission dieser Optik in einer Weise zu beschreiben, die eine routinemäßige Quantifizierung auf Basis der fundamentalen Parameter möglich ist. Die notwendigen Untersuchungen erfolgten an einem kommerziellen Mikro-RFA-Spektrometer, das für die Analyse im Kunst- und Kulturgutbereich entwickelt wurde. Zum einen wurden im Rahmen der Arbeit umfangreiche Charakterisierungsmessungen an der zum Spektrometer gehörenden Linse durchgeführt, um die grundsätzlichen Prozesse bei Strahlungstransport in Polykapillarlinsen besser zu verstehen. Dabei wurde besonders auf den Einfluss messungsbedingter Artefakte bei der Bestimmung der Linsenparameter geachtet. Zusätzlich wurden an Polykapillarhalblinsen Charakterisierungsuntersuchungen am Rasterelektronenmikroskop und mit Synchrotronstrahlung durchgeführt. Die Ergebnisse ergänzen die Erkenntnisse der Volllinsencharakterisierung, insbesondere den starken Einfluss der Messbedingungen auf die ermittelten Parameter. Zum anderen wurde ein neues Kalibrierungsverfahren entwickelt, welches die Beschreibung der Linsentransmission ohne vorherige Linsencharakterisierung ermöglicht. Das Verfahren wurde an zertifizierten Referenzmaterialien getestet. An verschiedenen Anwendungen aus dem Bereich der Archäometrie werden schließlich Quantifizierungsergebnisse präsentiert, so z. B. die Analyseergebnisse antiker römische Kupfermünzen, die im Rahmen eines Methodenvergleiches auch mit PIXE und Synchrotron- RFA untersucht wurden sowie Untersuchungsergebnisse historischer Pergamente und Schreibmaterialien.
In this study, we address the question of the
provenance and origin of the Dead Sea Scrolls manuscripts.
A characteristic low ratio of chlorine to bromine, corresponding
to that of the Dead Sea water, may serve as an indicator for
local production. For this aim we developed a non-destructive
procedure to determine the Cl/Br ratio in the parchment of
these manuscripts. Micro-X-ray fluorescence (µ-XRF) measurements
of a large number of parchment and leather
fragments from the Dead Sea Scrolls were analyzed with a
routine we developed based on fundamental parameter
quantification. This routine takes into account the absorption
of the collagen matrix and the influence of the different sample
thicknesses. To calculate the representative Cl/Br ratio for each
fragment, we investigated the lateral homogeneity and
determined the total mass deposition using the intensity of
the inelastically scattered, characteristic tube radiation. The
distribution of the Cl/Br ratios thus obtained from the µ-XRF
measurements make it possible to distinguish fragments
whose origin lies within the Dead Sea region from those
produced in other locations.
Nondestructive analyses of medieval reverse paintings on glass revealed the same dyes and pigments customarily used in panel paintings. However, there is one exception: the black colorant is not a carbon-based pigment, but black enamel. In this respect, the stylistic as well as the technical influence of stained glass artwork can clearly be seen on reverse paintings on glass. However, there is a crucial difference: in reverse paintings, the black enamel is not fired onto the glass but painted (cold painting). Additional analyses confirmed these findings. Based on these results, the art form "reverse painting on glass" has technically to be characterized as a mixture of "stained glass" and "panel painting" that nonetheless develops into a genre of its own.
Polycapillary halflenses are widely used to focus X-ray radiation onto a small spot. Additionally they can reduce the field of view of a semiconductor detector when placed in front of one. In 3D micro X-ray fluorescence spectroscopy (3D Micro-XRF) with synchrotron radiation, two polycapillary halflenses are used in a confocal geometry. Up until now, characterization measurements in the focal plane have only been performed in the case of the lens focusing parallel radiation. Assumptions have been made, that in the other case, when isotropic radiation from a spot source is transported to a detector, the acceptance distribution in the focal plane is also Gaussian. We performed measurements with an electron beam as well as a proton beam which confirm this assumption. In addition, a comparison between measurements in collecting and focusing mode show differences in spot size and transmission. These differences exemplify the fact that there is not one global spot size or transmission function of a polycapillary halflens. Illumination and divergence effects can alter both characteristic lens parameters.
In this study we demonstrate the possibility to identify the production area of the scrolls, coupling non-destructive quantitative analysis of race elements to spectroscopic investigation of the inks. This approach, that allowed us to determine the Dead Sea area as origin of 1QHodayot, is of general validity.
3D Micro X-ray fluorescence analysis was used for the investigation of reverse-glass paintings. The material-specific combination used in reverse-glass paintings leads to damage phenomena reinforced by glass corrosion. To elucidate the mechanism of corrosion processes taking place in the glass object depth profiles of mobile elements are of interest. In order to obtain elemental depth profiles of such kind of fragile objects the method of choice should be non-destructive. Our first results demonstrate the usefulness of the 3D Micro-XRF measurements for this kind of investigations. The assumption that certain binding media may initiate corrosion processes beginning at the interface glass/binding material could be confirmed.
The Dead Sea Scrolls belong to the most important cultural assets of mankind. Their long term preservation and study is a challenge that demands an interdisciplinary approach. As early as the 1950s natural scientists assisted the scholars in studying the scrolls. It was at this time that the first extensive study of the scroll material took place. It was found that most fragments were written not on leather but on parchment. In addition, a method for determining the age of the parchment was developed which is still of value today. In the 1990s the AMS-C14 method confirmed the palaeographic determination of the age of the manuscripts. The use of carbon ink throughout the scrolls is also consistent with the known scribal practices of that time. There are, however, manuscripts, and among them the famous Genesis Apocryphon Scroll, which exhibit ink corrosion, normally associated with iron-gall inks.
Today, 60 years after their discovery, a community of scientists from the Jewish National and University Library (JNUL), the Technical University of Berlin (TU Berlin), the Federal Institute for Materials Research and Testing (BAM) and Fritz-Haber-Institute of the MPG (FHI) set out to scientifically investigate the finds of Qumran using the most modern methods. The results of the study will be used to determine the provenance of the texts as well as to contribute to their long-term preservation. A considerable part of the non-destructive investigation is taking place in the Berlin State Library and at the Berliner Elektronenspeicherring-Gesellschaft für Synchrotronstrahlung , BESSY II.
Preliminary investigations, performed at the BAM on some fragments, were used to evaluate the extent to which X-ray analytical methods can provide information regarding the geographical origin of the fragments and match the individual pieces. The interpretation of the measurement results is made more difficult by age and storage of the objects. It is believed that ageing processes as well as conservation methods have altered the samples in addition to the changes caused by environmental influences.
In collaboration with the TU Berlin, the samples from the parchments found in the caves near Qumran were tested by means of three-dimensional synchrotron based X-ray fluorescence analysis (3D-SyXRF). The aim of this non-destructive investigation was the identification of the inorganic material used in the manufacture of the parchments.
The XRF experiments are supported by the non-destructive analysis by means of synchrotron based infrared spectroscopy (SyFTIR) in collaboration with BESSY II as well as optical and electron microscopy in collaboration with Fritz-Haber-Institute (FHI).