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Laser ablation inductively coupled plasma mass spectrometry (LA ICP MS) was used as a supporting ... more Laser ablation inductively coupled plasma mass spectrometry (LA ICP MS) was used as a supporting method for elemental analysis of historical glass investigated by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM=EDS). Investigated objects represent mainly late-and post-medieval glass objects (mostly Fac°onde-Venise vessels and nuppenbechers), window glass and chandeliers from excavation in Elbląg, Pozna n n and Wroclaw (Poland) or museums' historical collections. By applying LA ICP MS, it was possible to determine a number of elements which are present bellow the detection limit of SEM=EDS and to evaluate the homogeneity of investigated material. It was also possible to measure the content of boron in glass, the element which cannot be determined by SEM=EDS. Results obtained by SEM=EDS were used not only for routine screening of the glass composition, but also for the evaluation of the selection of standard reference materials for LA ICP MS measurements. A satisfacto-ry correlation between the results for major and minor elements obtained by both applied methods was achieved with a complementary determination of trace elements (Hf, Zr, Sb, Rb, Ti and B) by means of LA ICP MS.

Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist'... more Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist's material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr 1−x S x O 4 , with 0 ≤ x ≤ 0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods. Pure PbCrO 4 (crocoite in its natural form) has a deep yellow color and is relatively stable, while the coprecipitate with lead sulfate (PbCr 1−x S x O 4) has a paler shade and seems to degrade faster. This degradation is assumed to be related to the reduction of Cr(VI) to Cr(III). We show that, when the the sulfur(S)-content in chrome yellow increases, the band gap increases. Typically, when increasing the band gap, one might assume that a decrease in photoactivity is the result. However, the photoactivity relative to the Cr content and, thus, Cr reduction of sulfur-rich PbCr 1−x S x O 4 is found to be much higher compared to the sulfur-poor or nondoped lead chromates. This discrepancy can be explained by the evolution of the crystal and electronic structure as a function of the sulfur content: first-principles density functional theory calculations show that both the absorption coefficient and reflection coefficients of the lead chromates change as a result of the sulfate doping in such a way that the generation of electron−hole pairs under illumination relative to the total Cr content increases. These changes in the material properties explain why paler shade yellow colors of this pigment are more prone to discoloration. The electronic structure calculations also demonstrate that lead chromate and its coprecipitates are p-type semiconductors, which explains the observed reduction reaction. Because understanding this phenomenon is valuable in the field of cultural heritage, this study is the first joint action of photoelectrochemical measurements and first-principles calculations to approve the higher tendency of sulfur-rich lead chromates to darken.

Orpiment and realgar, both arsenic sulfide pigments respectively used for their vivid yellow and ... more Orpiment and realgar, both arsenic sulfide pigments respectively used for their vivid yellow and red-orange hues, are two of many artists' pigments that appear not to be stable upon light exposure, quickly degrading to arsenic trioxide and arsenate. This often results in whitening or transparency in the painted surfaces. While conventional techniques such as microscopic Raman (m-RS) and microscopic Fourier transform infrared (m-FTIR) spectroscopies can allow a quick and relatively easy identification of the orpiment, realgar, artificial arsenic sulfide glass and, to some extent, arsenic oxide, the identification and visualization of distributions of the degradation products – and especially arsenate compounds – in the paint micro-samples is generally more challenging. This challenge is due to the rather unfavorable limit of detection and low spectral resolution of such conventional spectroscopic techniques. This restricts the conclusions that can be drawn regarding the conservation state of valuable works of art. In this paper, we present how synchrotron radiation (SR) based techniques can overcome this challenge while working on painting cross-sections taken from a 17 th-century painting by the Flemish artist Danï el Seghers (oil on canvas, Statens Museum for Kunst, Denmark) and an 18 th-century French Chinoiserie (private collection, France). SR micro-X-ray fluorescence (m-XRF) mapping analysis performed on a visually degraded orpiment-containing paint stratigraphy reveals that arsenic is distributed throughout the entire cross-section, while X-ray absorption near edge structure (m-XANES) demonstrated that the arsenic is present in both arsenite (As-III) and arsenate (As-V) forms. The latter compound(s), despite being barely identifiable by means of FTIR, were not only located at the surface of large and partially altered grains of arsenic sulfide but also spread throughout the entire paint stratigraphy. Their presence and distribution are attributed either to the complete degradation of smaller arsenic sulfide grains or to migration of the arsenates within the paint layer away from their original location of formation. The combination of m-XRF and m-XANES was very useful for the characterization of the advanced degradation state of the arsenic-containing pigments in paint systems; this type of information could not be obtained by means of conventional spectroscopic methods of microanalysis.

In this study, a combination of elemental analytical techniques (MA-XRF and SEM-EDX) were used to... more In this study, a combination of elemental analytical techniques (MA-XRF and SEM-EDX) were used to localize arsenic sulfide pigments within a 17 th-century Dutch painting and in the stratigraphy of an 18 th-century Flemish polychrome sculpture. Once located, Raman spectroscopy was used to obtain the vibrational signature of the arsenic sulfide pigments employed. By means of the latter analytical technique and due to the very distinctive Raman scattering signal of the various arsenic sulfide compounds, it was possible to identify the arsenic-based pigments as natural orpiment and amorphous arsenic sulfide. In the latter case, based on the minor bands observed and the good condition of the paint layers, it was possible to identify pararealgar, the orangey-yellow to yellow degradation product of realgar, as the initial arsenic sulfide material used for the synthesis of the amorphous pigment. To the best of our knowledge, this is the first time that combined pararealgar/amorphous arsenic sulfide Raman spectra are reported in historical samples. Therefore, this would be the first identification of pararealgar as the starting material to produce amorphous arsenic sulfide pigments used in artworks.

Journal of Physics: Conference Series, 2009

ABSTRACT Journal article

Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). Show f... more Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). Show full item record. Title: Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). ...

Journal of Cultural Heritage, 2010

The chemical composition of 11 glass panes originating from two 13th century non-figurative windo... more The chemical composition of 11 glass panes originating from two 13th century non-figurative windows were analyzed by means of Scanning Electron Microscopy-Energy Dispersive X-ray system (SEM-EDX). The windows were discovered in the back-wall of the triforium during the restoration of the choir of the cathedral St. Michael and St. Gudule in Brussels (Belgium). In order to determine if these windows were fabricated with glass of different origin or not, the compositional difference between the panes were compared with the variation in composition as a result of the following causes: (1) compositional fluctuation between panes cut from the same sheet of glass, (2) compositional fluctuation caused when panes are cut from different sheets that were made with the same batch, (3) compositional fluctuation caused when the glass is made from different batches at the same production center, and (4) compositional fluctuation as a result of glass produced at different fabrication centers.

… and Facilities for …, 2006

49 MICRO-FOCUSED XRF, XAFS AND XRD INVESTIGATIONS OF U AND As SPECIATION IN LIGNITE-RICH CLAYEY S... more 49 MICRO-FOCUSED XRF, XAFS AND XRD INVESTIGATIONS OF U AND As SPECIATION IN LIGNITE-RICH CLAYEY SEDIMENT BORE CORES FROM RUPRECHTOV, CZECH REPUBLIC MA Denecke1, K. Janssens2, A. Somogyi3, K. Proost2, J. Rothe1, R. Simon1, U. Noseck4 ...

Page 1. ANNALES ANNALES du 17e Congrès of the 17th Congress de l&... more Page 1. ANNALES ANNALES du 17e Congrès of the 17th Congress de l'ASSOCIATION INTERNATIONALE pour l'HISTOIRE du VERRE of the INTERNATIONAL ASSOCIATION for the HISTORY of GLASS Anvers, 2006 2006 ...

Archaeometry, Jan 1, 2009

In this work we attempt to elucidate the chronological and geographical origin of deeply coloured... more In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope – energy-dispersive system (SEM–EDS, 63 samples analysed) and laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti-poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM–EDS and LA–ICP–MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150.

Journal of Archaeological Science, Jan 1, 2011

Archaeometric research on glass artefacts is continuously evolving and is converging towards a mu... more Archaeometric research on glass artefacts is continuously evolving and is converging towards a multidisciplinary research domain where different types of techniques are applied depending on the questions asked and the circumstances involved. The technique described in this work is optical spectroscopy. The benefit of this technique being the possibility of building up a knowledge database for a large amount of material in a relatively short period of time and with a relatively limited budget. This is of particular interest for the investigation of extensive and/or unexplored glass collections where a first-line analysis of artefacts could facilitate the selection of material needing further and more detailed examination.This publication explores the extent to which optical spectroscopy can be used for a first-line analysis of green coloured glass artefacts from the Roman period. It is shown that the colour coordinates calculated from the measured transmission spectrum could reveal information about the fragment under study. In particular it is shown that 1) based on the position of the calculated colour values on the colour diagram (CIE1931) one could easily know whether the artefact was coloured using only iron or if copper oxides were also present. In the case of the artefact owing its colour solely to the presence of iron, the distance between the measured colour values and the colour diagram’s white point can roughly indicate the iron concentration of the sample; 2) artefacts that were fabricated under similar furnace conditions can also be identified on the colour diagram; 3) samples with identical compositions and fabrication conditions but with different sample thickness, gave rise to a variation in the colour coordinates, thus allowing optical spectroscopy to help identify fragments which might belong to the same object.► Optical spectroscopy used to study green coloured Roman glasses. ► CIE1931 colour values reveals the type of colorant (iron, copper, …). ► CIE1931 colour values identifies fragments fabricated under similar conditions. ► CIE1931 colour values identifies fragments which might belong to a same object.

Laser ablation inductively coupled plasma mass spectrometry (LA ICP MS) was used as a supporting ... more Laser ablation inductively coupled plasma mass spectrometry (LA ICP MS) was used as a supporting method for elemental analysis of historical glass investigated by means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM=EDS). Investigated objects represent mainly late-and post-medieval glass objects (mostly Fac°onde-Venise vessels and nuppenbechers), window glass and chandeliers from excavation in Elbląg, Pozna n n and Wroclaw (Poland) or museums' historical collections. By applying LA ICP MS, it was possible to determine a number of elements which are present bellow the detection limit of SEM=EDS and to evaluate the homogeneity of investigated material. It was also possible to measure the content of boron in glass, the element which cannot be determined by SEM=EDS. Results obtained by SEM=EDS were used not only for routine screening of the glass composition, but also for the evaluation of the selection of standard reference materials for LA ICP MS measurements. A satisfacto-ry correlation between the results for major and minor elements obtained by both applied methods was achieved with a complementary determination of trace elements (Hf, Zr, Sb, Rb, Ti and B) by means of LA ICP MS.

Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist'... more Chrome yellow refers to a group of synthetic inorganic pigments that became popular as an artist's material from the second quarter of the 19th century. The color of the pigment, in which the chromate ion acts as a chromophore, is related to its chemical composition (PbCr 1−x S x O 4 , with 0 ≤ x ≤ 0.8) and crystalline structure (monoclinic/orthorhombic). Their shades range from the yellow-orange to the paler yellow tones with increasing sulfate amount. These pigments show remarkable signs of degradation after limited time periods. Pure PbCrO 4 (crocoite in its natural form) has a deep yellow color and is relatively stable, while the coprecipitate with lead sulfate (PbCr 1−x S x O 4) has a paler shade and seems to degrade faster. This degradation is assumed to be related to the reduction of Cr(VI) to Cr(III). We show that, when the the sulfur(S)-content in chrome yellow increases, the band gap increases. Typically, when increasing the band gap, one might assume that a decrease in photoactivity is the result. However, the photoactivity relative to the Cr content and, thus, Cr reduction of sulfur-rich PbCr 1−x S x O 4 is found to be much higher compared to the sulfur-poor or nondoped lead chromates. This discrepancy can be explained by the evolution of the crystal and electronic structure as a function of the sulfur content: first-principles density functional theory calculations show that both the absorption coefficient and reflection coefficients of the lead chromates change as a result of the sulfate doping in such a way that the generation of electron−hole pairs under illumination relative to the total Cr content increases. These changes in the material properties explain why paler shade yellow colors of this pigment are more prone to discoloration. The electronic structure calculations also demonstrate that lead chromate and its coprecipitates are p-type semiconductors, which explains the observed reduction reaction. Because understanding this phenomenon is valuable in the field of cultural heritage, this study is the first joint action of photoelectrochemical measurements and first-principles calculations to approve the higher tendency of sulfur-rich lead chromates to darken.

Orpiment and realgar, both arsenic sulfide pigments respectively used for their vivid yellow and ... more Orpiment and realgar, both arsenic sulfide pigments respectively used for their vivid yellow and red-orange hues, are two of many artists' pigments that appear not to be stable upon light exposure, quickly degrading to arsenic trioxide and arsenate. This often results in whitening or transparency in the painted surfaces. While conventional techniques such as microscopic Raman (m-RS) and microscopic Fourier transform infrared (m-FTIR) spectroscopies can allow a quick and relatively easy identification of the orpiment, realgar, artificial arsenic sulfide glass and, to some extent, arsenic oxide, the identification and visualization of distributions of the degradation products – and especially arsenate compounds – in the paint micro-samples is generally more challenging. This challenge is due to the rather unfavorable limit of detection and low spectral resolution of such conventional spectroscopic techniques. This restricts the conclusions that can be drawn regarding the conservation state of valuable works of art. In this paper, we present how synchrotron radiation (SR) based techniques can overcome this challenge while working on painting cross-sections taken from a 17 th-century painting by the Flemish artist Danï el Seghers (oil on canvas, Statens Museum for Kunst, Denmark) and an 18 th-century French Chinoiserie (private collection, France). SR micro-X-ray fluorescence (m-XRF) mapping analysis performed on a visually degraded orpiment-containing paint stratigraphy reveals that arsenic is distributed throughout the entire cross-section, while X-ray absorption near edge structure (m-XANES) demonstrated that the arsenic is present in both arsenite (As-III) and arsenate (As-V) forms. The latter compound(s), despite being barely identifiable by means of FTIR, were not only located at the surface of large and partially altered grains of arsenic sulfide but also spread throughout the entire paint stratigraphy. Their presence and distribution are attributed either to the complete degradation of smaller arsenic sulfide grains or to migration of the arsenates within the paint layer away from their original location of formation. The combination of m-XRF and m-XANES was very useful for the characterization of the advanced degradation state of the arsenic-containing pigments in paint systems; this type of information could not be obtained by means of conventional spectroscopic methods of microanalysis.

In this study, a combination of elemental analytical techniques (MA-XRF and SEM-EDX) were used to... more In this study, a combination of elemental analytical techniques (MA-XRF and SEM-EDX) were used to localize arsenic sulfide pigments within a 17 th-century Dutch painting and in the stratigraphy of an 18 th-century Flemish polychrome sculpture. Once located, Raman spectroscopy was used to obtain the vibrational signature of the arsenic sulfide pigments employed. By means of the latter analytical technique and due to the very distinctive Raman scattering signal of the various arsenic sulfide compounds, it was possible to identify the arsenic-based pigments as natural orpiment and amorphous arsenic sulfide. In the latter case, based on the minor bands observed and the good condition of the paint layers, it was possible to identify pararealgar, the orangey-yellow to yellow degradation product of realgar, as the initial arsenic sulfide material used for the synthesis of the amorphous pigment. To the best of our knowledge, this is the first time that combined pararealgar/amorphous arsenic sulfide Raman spectra are reported in historical samples. Therefore, this would be the first identification of pararealgar as the starting material to produce amorphous arsenic sulfide pigments used in artworks.

Journal of Physics: Conference Series, 2009

ABSTRACT Journal article

Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). Show f... more Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). Show full item record. Title: Two fragments of mold-blown glass beakers with Greek inscriptions from Tongeren (Belgium). ...

Journal of Cultural Heritage, 2010

The chemical composition of 11 glass panes originating from two 13th century non-figurative windo... more The chemical composition of 11 glass panes originating from two 13th century non-figurative windows were analyzed by means of Scanning Electron Microscopy-Energy Dispersive X-ray system (SEM-EDX). The windows were discovered in the back-wall of the triforium during the restoration of the choir of the cathedral St. Michael and St. Gudule in Brussels (Belgium). In order to determine if these windows were fabricated with glass of different origin or not, the compositional difference between the panes were compared with the variation in composition as a result of the following causes: (1) compositional fluctuation between panes cut from the same sheet of glass, (2) compositional fluctuation caused when panes are cut from different sheets that were made with the same batch, (3) compositional fluctuation caused when the glass is made from different batches at the same production center, and (4) compositional fluctuation as a result of glass produced at different fabrication centers.

… and Facilities for …, 2006

49 MICRO-FOCUSED XRF, XAFS AND XRD INVESTIGATIONS OF U AND As SPECIATION IN LIGNITE-RICH CLAYEY S... more 49 MICRO-FOCUSED XRF, XAFS AND XRD INVESTIGATIONS OF U AND As SPECIATION IN LIGNITE-RICH CLAYEY SEDIMENT BORE CORES FROM RUPRECHTOV, CZECH REPUBLIC MA Denecke1, K. Janssens2, A. Somogyi3, K. Proost2, J. Rothe1, R. Simon1, U. Noseck4 ...

Page 1. ANNALES ANNALES du 17e Congrès of the 17th Congress de l&... more Page 1. ANNALES ANNALES du 17e Congrès of the 17th Congress de l'ASSOCIATION INTERNATIONALE pour l'HISTOIRE du VERRE of the INTERNATIONAL ASSOCIATION for the HISTORY of GLASS Anvers, 2006 2006 ...

Archaeometry, Jan 1, 2009

In this work we attempt to elucidate the chronological and geographical origin of deeply coloured... more In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope – energy-dispersive system (SEM–EDS, 63 samples analysed) and laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti-poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM–EDS and LA–ICP–MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150.

Journal of Archaeological Science, Jan 1, 2011

Archaeometric research on glass artefacts is continuously evolving and is converging towards a mu... more Archaeometric research on glass artefacts is continuously evolving and is converging towards a multidisciplinary research domain where different types of techniques are applied depending on the questions asked and the circumstances involved. The technique described in this work is optical spectroscopy. The benefit of this technique being the possibility of building up a knowledge database for a large amount of material in a relatively short period of time and with a relatively limited budget. This is of particular interest for the investigation of extensive and/or unexplored glass collections where a first-line analysis of artefacts could facilitate the selection of material needing further and more detailed examination.This publication explores the extent to which optical spectroscopy can be used for a first-line analysis of green coloured glass artefacts from the Roman period. It is shown that the colour coordinates calculated from the measured transmission spectrum could reveal information about the fragment under study. In particular it is shown that 1) based on the position of the calculated colour values on the colour diagram (CIE1931) one could easily know whether the artefact was coloured using only iron or if copper oxides were also present. In the case of the artefact owing its colour solely to the presence of iron, the distance between the measured colour values and the colour diagram’s white point can roughly indicate the iron concentration of the sample; 2) artefacts that were fabricated under similar furnace conditions can also be identified on the colour diagram; 3) samples with identical compositions and fabrication conditions but with different sample thickness, gave rise to a variation in the colour coordinates, thus allowing optical spectroscopy to help identify fragments which might belong to the same object.► Optical spectroscopy used to study green coloured Roman glasses. ► CIE1931 colour values reveals the type of colorant (iron, copper, …). ► CIE1931 colour values identifies fragments fabricated under similar conditions. ► CIE1931 colour values identifies fragments which might belong to a same object.