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Le Touquet – Paris-Plage, France

Bertrand L.,French National Center for Scientific Research | Bertrand L.,Synchrotron Soleil | Refregiers M.,Synchrotron Soleil | Berrie B.,National Gallery of Art | And 2 more authors.

In order to fully characterize the zinc white artists' pigment (ZnO), much used since the mid-nineteenth century, three samples collected in the early 20th century were studied using a combination of synchrotron and macroscopic photoluminescence spectroscopy and imaging. An improved microscope setup based on synchrotron microspectroscopy and microimaging was used to study the powders dispersed onto indium foil. The synchrotron setup offered a diffraction-limited resolution of 153 nm. The PL spectra of individual grains were measured and the distribution of particles' emission spectra was mapped at the nanoscale. The results revealed that while the samples have apparent homogeneous photoluminescence behavior at the macroscale (bulk), their PL signatures are inhomogeneous below 20 μm. At the nanoscale the three powder samples have quite different PL signatures. Different sources, perhaps even different batches, of zinc white might be readily differentiated using this method. © 2013 The Royal Society of Chemistry. Source

Daher C.,University Pierre and Marie Curie | Paris C.,University Pierre and Marie Curie | Le Ho A.-S.,French National Center for Scientific Research | Bellot-Gurlet L.,University Pierre and Marie Curie | Echard J.-P.,Laboratoire Of Recherche Et Of Restauration
Journal of Raman Spectroscopy

Various natural organic film-making media from several chemical familieshave been used as varnishes. An improvement in the identification of thesematerials by a combination of Raman and infrared spectroscopies is presentedhere. Fourteen unaged reference samples representative of resins, glues, gumsand oils were analyzed. FT-Raman and infrared spectra were all compared in orderto discriminate the different classes of organic media by considering theirspectroscopic features. It led to a flowchart for material discrimination basedon simple, notable and specific criteria. It appears that the different families(gums, glues, oils and resins) and subfamilies (di/triterpenoids resins) areeasily differentiated thanks to their specific structural composition. However,differentiating between compounds from a same subgroup, for example diterpenoidresins, could be ambiguous because the spectra depend on the sample aspect, ageand degradations. Copyright © 2010 John Wiley & Sons, Ltd. Source

Echard J.-P.,Laboratoire Of Recherche Et Of Restauration | Bertrand L.,Synchrotron Soleil
Spectroscopy Europe

A study was conducted to demonstrate complementary spectroscopic analyses of varnishes of historical musical instruments. The investigations were conducted to define optimal conservation conditions for these instruments, study the aging of materials in various contexts, and obtain a better understanding of the ancient instruments-making techniques. Micro-samples of varnish samples cut in cross section were analyzed using synchrotron radiation-based micro-Fourier transform infrared (SR-FT-IR) spectroscopy. Microformed thin slices were also analyzed in transmission mode of transflection mode for the investigations. Researchers were able to analyze the two layers of varnish on a set of instruments made by Antonio Stradivari. The FT-IR spectra also recorded revealed little difference between the two investigated layers and showed they were of oil-based media. Source

Thoury M.,National Gallery of Art | Thoury M.,French Natural History Museum | Echard J.-P.,Laboratoire Of Recherche Et Of Restauration | Refregiers M.,Synchrotron Soleil | And 5 more authors.
Analytical Chemistry

UV-visible luminescence techniques are fre-quently used for the study of cultural heritage materials, despite their limitations for identification and discrimination in the case of complex heterogeneous materials. In contrast to tabletop setups, two methods based on the vacuum ultraviolet (VUV)-UV-visible emission generated at a bending magnet of a synchrotron source are described. The main advantages of the source are the extended wavelength range attained, the continuous tunability of the source, and its brightness, leading to a submicrometer lateral resolution. Raster-scanning microspectroscopy and full-field microimaging were implemented and tested at the DISCO beamline (synchrotron SOLEIL, France). Investigative measurements were performed on a sample from a varnished musical instrument and a paint sample containing the pigment zinc white (ZnO) in order to illustrate some of the challenges analyzing heterogeneous cultural heritage cross-section samples with the novel imaging approach. The data sets obtained proved useful for mapping organic materials at the submicrometer scale and visualizing heterogeneities of the semiconductor pigment material. We propose and discuss the combined use of raster-scanning microspectroscopy and full-field microimaging in an integrated analytical methodology. Synchrotron UV luminescence appears as a novel tool for identification of craftsmen's and artists' materials and techniques and to assess the condition of artifacts, from the precise identification and localization of luminescent materials. © 2011 American Chemical Society. Source

Echard J.-P.,Laboratoire Of Recherche Et Of Restauration | Echard J.-P.,French National Center for Scientific Research | Bertrand L.,Synchrotron Soleil | Von Bohlen A.,Leibniz Institute for Analytical Sciences | And 9 more authors.
Angewandte Chemie - International Edition

Figure Presented What is Stradivari's "secret"? The composition of the mythical varnish that coats Stradivari's violins has raised controversial assumptions for the past two centuries. By using a complementary array of analytical tools, the chemical microstratigraphy of these varnishes has been established. The results provide information on the materials and techniques that were used by the Master, with a detailed characterization of the varnish chemical equation presentation © 2010 Wiley-VCH Verlag GmbH &. Co. KGaA, Weinheim. Source

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