Search

X-ray fluorescence spectroscopy (XRF) plays an important role for elemental analysis in a wide range of scientific fields, especially in cultural heritage.

In the present work, four wooden panels dated to the second half of the 6th century B.C., discovered in 1934 inside a cave located in Corinthia near the ancient city of Sicyon, are examined. The “Pitsa pinakes” are the oldest known examples of panel painting in ancient Greece. The application of non-invasive and non-contact imaging and analytical techniques (imaging techniques, including infrared-reflected and visible-induced luminescence, microscopy and mapping XRF) has brought to light significant evidence on the materials and the technology of the paintings. Multiple figurative elements that had remained previously “unseen”, due to the losses and degradation of the original paint layers, were recovered, allowing for a better understanding of the original iconography. Furthermore, imaging techniques have largely contributed to an enhanced reading and understanding of the inscriptions preserved on the panels, including the personal name “Kalypso” on the panel depicting a ritual dance (inv. 16467); this name had hitherto been known only through literary sources.

This study presents the results of a technical and art historical study of an important Gandharan head from the Victoria and Albert Museum. For several years, the head has played an important role in the history of Gandharan art, because of its high aesthetic qualities. However, the head has received limited scholarly attention since its first display in the 1930s. This study reviewed the head’s physical, curatorial and conservation history and determined its construction using non-invasive and non-contact investigative techniques (technical imaging, FTIR, XRF and FORS). The support consists of several layers of a lime- and gypsum-based plaster (gauging plaster) and only salient elements of the face (e.g. lips, eyes and hairline) and the hair were painted, with a high-quality red ochre and with an unidentified black pigment, respectively. A careful examination of the construction of the head allowed to determine that it probably belonged to an iconic representation of the Buddha, as opposed to a narrative scene.

6,6′-dibromoindigo (DBI) is the main component of Tyrian purple, or Imperial purple, one of the most controversial, sought-after and expensive colouring matters of antiquity. Evidence of its use, both as a pigment and as a dye, is found in the archaeological record, especially in the countries surrounding the Mediterranean basin. The photo-induced luminescence properties of a synthetic sample of DBI were studied in this paper. Time-Dependent Density Functional theory (TD-DFT) was used to predict and rationalise the optical absorption and emission properties of DBI in DMSO and compared with the experimental data. The emission properties of the solid-state sample were characterised for the first time. DBI shows an emission maximum in the infrared range, at about 870 nm, and lifetime in the picosecond range. The spatial distribution of the photo-induced luminescence emission could also be recorded using a commercial infrared-sensitive camera, opening up the possibility of non-invasively investigating the use of DBI on historical artefacts.

This article presents two essays by the renowned Icelandic manuscript collector Árni Magnússon (1663 ‒ 1730): De gothicæ lingvæ nomine [On the expression ‘the Gothic language’] and Annotationes aliqvot de lingvis et migrationibus gentium septentrionalium [Some notes on the languages and migrations of the northern peoples]. The two essays are here edited and published in their original language, Latin. Moreover, an English translation is also presented for ease of access. After a short introduction (§ 1), a historical overview of the academic strife between Denmark and Sweden is given (§ 2). Subsequently (§ 3), Árni Magnússon’s life and work are presented. In the following section (§ 4), the manuscript containing the two essays, AM 436 4to, is described. The two essays are then edited and translated in section 5. In the last section (§ 6), the two works are commented and Árni Magnússon’s scholarly thought evaluated.

Infrared reflectography of the Mughal painting known as Princes of the House of Timur (British Museum, 1913,0208,0.1) suggests at least four phases of overpainting, reveals previously unseen inscriptions, clarifies issues of iconography, and provides parallels with workshop practice—in particular, with bookbinding and book illustration.

The widespread occurrence of Indian yellow on an early 17th-century wall painting in Rajasthan (India) was initially indicated by photo-induced luminescence imaging of the painted scheme in the Badal Mahal within the Garh Palace (Bundi). The presence of the organic pigment was subsequently confirmed by HPLC-ESI-Q-ToF. The results of a multi-analytical study focusing on two samples from the wall painting and two reference pigments from the British Museum and National Gallery (London, UK) are presented here. The research focused on the possible causes for the different yellow/orange hues observed in the painting samples. Analysis of cross-sections with SEM-EDS revealed similar elemental composition for the Indian yellow paint layers, but different underlying layers, indicating a variation in painting technique. The composition of the Indian yellow samples was investigated by HPLC-ESI-Q-ToF with both positive and negative ionisation. In addition to euxanthic acid and euxanthone, a sulphonate derivative of euxanthone was found to be present in all samples, while relative amounts of the three components varied. Flavonoid molecules—morin, kaempferol, quercetin and luteolin—were also detected in one wall painting sample (characterised by a brighter yellow colour) and not in the sample that was more orange. The optical properties of the samples were characterised by photoluminescence spectroscopy in both solid state and aqueous solution. The contribution of each organic compound to the emission spectrum of Indian yellow in solution was also investigated by time-dependent density functional theory (TDDFT) calculations. Small differences in terms of spectral shift were observed in solid state experiments, but not in solution, suggesting that the spectral differences in the emission spectrum were mostly due to different contributions of solid-state arrangements, most likely driven by π-π stacking and/or hydrogen bonds. However, a slight difference at high energies was observed in the spectra acquired in solution and TDDFT calculations permitted this to be ascribed to the different chemical composition of the samples. Time-resolved measurements highlighted di-exponential lifetime decays, confirming the presence of at least two molecular arrangements. Py(HMDS)-GC–MS was also used for the first time to characterise Indian yellow and the trimethylsilyl derivative of euxanthone was identified in the pyrograms, demonstrating it to be a suitable marker for the identification of the pigment in complex historic samples.

none 9 si The optical properties (photophysics and imaging) of Indian yellow were investigated both in solid state and in aqueous solution and correlated with its chemical composition. The analyses were corroborated by a theoretical study carried out on the different xanthone derivatives that comprise the pigment under investigation, both as isolated molecules and in a polar (protic) solvent, to help the assignment of the excited states involved in the photo-induced process. Knowledge of its relatively high photoluminescence quantum yield (PLQY 0.6%), excitation and emission spectra and lifetime decays enhances the potential for reliable identification using non-invasive photo-induced luminescence imaging techniques. New insights into the chemical composition of the pigment, such as the identification of a sulphonate derivative of euxanthone, and its extensive occurrence on a 17th-century Indian wall painting are also reported for the first time in this study. Martin de Fonjaudran, Charlotte; Acocella, Angela; Accorsi, Gianluca; Tamburini, Diego; Verri, Giovanni; Rava, Amarilli; Whittaker, Samuel; Zerbetto, Francesco; Saunders, David Martin de Fonjaudran, Charlotte; Acocella, Angela; Accorsi, Gianluca; Tamburini, Diego; Verri, Giovanni; Rava, Amarilli; Whittaker, Samuel; Zerbetto, Francesco; Saunders, David

Bulk thermal alterations to chlorite schist occurring at temperatures above 450 °C are traditionally studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, or thermogravimetric analysis (TGA), but lower temperature changes that lead to structural and chemical alteration, including changes in oxidation state that are not followed by a crystalline modification, are not detectable using these techniques. In this paper we present the results of the first study to examine the application of fiber-optic reflection spectroscopy (FORS) for the detection and quantification of low-temperature thermal alterations in chlorite schist. Such changes have been observed during research on the thermal behavior of medieval (12th–13th centuries AD) chlorite cooking pots from the archaeological site of Merv, Turkmenistan. FORS was used to investigate these changes, testing the archaeological samples against a model data set of experimental reference specimens. The results demonstrate the potential of FORS for tracking low-temperature thermal alterations and offer the opportunity to examine temperatures attained by ancient chlorite vessels during their past use in cooking activities.

Egyptian blue was extensively used throughout the areas surrounding the Mediterranean from early dynastic Egypt until after the Roman Empire ended. A new, easily applied, technique to detect and map this pigment has been developed that takes advantage of its very strong photo-induced infrared luminescence. Using this method, single particles of pigment can be detected, even when concealed by layers of discoloured organic binding media, varnishes or inorganic patinas. A survey of sculptures, friezes, mosaics and wall paintings from the ancient cultures of the Mediterranean and the Middle East has revealed expected and unexpected occurrences of Egyptian blue and rediscovered lost decorative patterns. This technique not only offers information on the manufacture, decoration and condition of the object, but also provides an opportunity to map the use of Egyptian blue both geographically and temporally. These new perspectives on ancient polychromy can help to inform future preservation strategies and c...

The aim of this study is to develop a method for the non-invasive and in situ identification of organic binders in wall paintings by fiber optic mid-FTIR reflectance spectroscopy. The non-invasive point analysis methodology was set-up working on a wide set of wall painting replicas of known composition and using statistical multivariate methods, in particular principal component analysis (PCA), for the interpretation, understanding, and management of data acquired with reflectance mid-FTIR spectroscopy. Results show that PCA can be helpful in managing and preliminary sorting of the large amount of spectra typically collected during non-invasive measurement campaigns and highlight further avenues for research. The developed PCA model was finally applied to the case of a Renaissance wall painting by Perugino assessing it predictability as compared to the interpretation of the single spectrum.

A group of 17 Italian fifteenth-century metalpoint drawings were examined using near-infrared reflectography and analysed non-invasively by X-ray fluorescence and Raman spectrometry. Metals, including silver and lead, reflect infrared (IR) radiation specularly and selectively. As expected, all of the lead-based metalpoint in this group of drawings proved to be entirely opaque when examined by IR reflectography. However, the silver-based metalpoint found on these drawings was observed to be wholly or partially transparent to infrared radiation in the 800–1700 nm range. The results obtained on drawings were compared with those from reference material of known composition. The response of silver-based metalpoint to infrared radiation is here attributed to the presence of silver corrosion products, particularly silver sulphide (Ag2S), a commonly encountered degradation product of silver. This compound shows high transmission in the spectral range under investigation.

The in situ produced cosmogenic beryllium isotope, 10 Be, in flint artifacts from different layers in prehistoric caves can provide information on flint procurement. The buildup of 10 Be in a flint matrix is related to the exposure time of the flint to cosmic rays. Although this exposure history can be complex, the 10 Be content of flint assemblages can show whether the raw material was obtained from shallow mining and/or surface collection as opposed to sediments two or more meters below the surface. Flint artifact assemblages from two Palaeolithic caves in Israel, Tabun and Qesem, were analyzed. In Tabun cave the flint artifacts from Lower Layer E (Acheulo-Yabrudian, around 400 000–200 000 yr) contain very small amounts of 10 Be, which is consistent with flint procured from sediments two or more meters deep. Artifacts from above and below Tabun Lower Layer E show a more complex distribution, as do artifacts from all layers of Qesem cave (Acheulo-Yabrudian). This is probably due to the fact that they were surface collected and/or mined from shallow (less than 2 m) depths. We show here that artifact assemblages have different concentrations of 10 Be, indicating different raw material procurement strategies.

Manganese blue is a synthetic barium manganate(VI) sulphate compound that was produced from 1935 to the 1990s and was used both as a blue pigment in works of art and by conservators in the restoration of paintings. The photophysical properties of the compound are described as well as the setup needed to record the spatial distribution of the pigment in works of art.

It has been shown [1] that an m = 0 instability of a Z-pinch carrying a current of the order of 10 MA, with a rise time inferior to 10 nsec can generate a spark capable of igniting a fusion detonation in the adjacent DT plasma channel. A possible method for generating such currents, necessary for the implosion of an initial large radius, low temperature Z-pinch, can be a radial implosion of a cylindrical fast liner. The problem has been addressed in a previous publication, [2][3][4][5], without considering the role played by an initially impressed m = 0 perturbation, a mechanism indispensable for the generation of a spark. The liner/Z-pinch dynamics can be solved at several levels of physical model completeness. The first correspond to a zero-dimensional model in which the liner has a given mass per cm length and a zero thickness, the plasma is compressed adiabatically and is isotropic, there are no energy losses and no Joule heating. The second level is one-dimensional. The Z-pinch plasma is described by the full set of MHD, 2 fluid equations. The liner is treated first as thin and incompressible and subsequently it is assumed that it has a finite thickness and is composed of a heavy ion plasma, having an artificial but realistic EOS. Both plasma and liner are considered uniform in the Z-direction and only D-T reactions are considered. We shall show that, given sufficient energy and speed of the liner, the Z-pinch can reach a volume ignition. The third level is two-dimensional. Plasma and liner are treated as in the 2nd level but either the Z-pinch or the liner is perturbed by an m = 0 non-uniformity. Provided the liner energy is high enough and the initial m = 0 perturbation is correctly chosen, the final neck plasma can act as a spark for D-T ignition. Fil: Bilbao, Luis Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentina Fil: Bernal, Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Física del Plasma. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Física del Plasma; Argentina Fil: Linhart, J.G.. Università di Ferrara; Italia Fil: Verri, G.. Università di Ferrara; Italia

A model of energy transfer from a heavy slow liner to a light and fast one is presented. Simple criteria for the optimum mass ratio of the two liners are derived and made more precise by a numerical solution of the equations of motion. Practical limitations and an application to inertial confinement fusion are mentioned.

Visible-induced luminescence imaging in the near infrared range (800-1700 nm) can play a key role in the spatial characterization of certain historical blue pigments (principally Egyptian blue, Han blue and Han purple). All three of these pigments show a very strong infrared emission when excited across the visible range. The setup required for this type of measurement comprises a recording device with some sensitivity to near infrared radiation and an excitation source in the visible range. Inexpensive and widely available excitation radiation sources that can be used for this application include fluorescent lamps and LEDs. While visible LEDs do not usually emit infrared radiation, commercially available fluorescent tubes may emit some stray infrared radiation. Although the presence of such stray infrared radiation may in some cases be considered beneficial, allowing the user easily to locate the presence of the pigments under investigation within the composition of the piece, it can be easily removed using a simple subtraction method. This method, based on the measurement of the reflective properties of the surface under investigation in the emission range of the luminescent pigments, is described. The emission results obtained for Egyptian blue, Han blue and Han purple are compared to those of a set of representative historical and modern blue pigments, including manganese blue, which was the only other pigment found to show detectable luminescence properties. Examples of the application of visible-induced luminescence imaging to archaeological objects of the Antonine period (AD 100-200) in the collections of the British Museum are also presented.

The variations of the fluorescence emission of carmine lake travelling through an absorbing and scattering medium, such as a paint layer, were investigated by ultraviolet (UV)–visible absorption, fluorescence spectroscopy, and imaging techniques. Samples of the lake were studied in dilute and saturated solutions, on a reference test panel and a real case study. Relevant spectral modifications have been observed as a function of the lake concentration mainly consisting of a fluorescence quenching, red shift of emission maxima, and deformation of emission band. The application of a correction factor based on the Kubelka–Munk model allowed fluorescence spectra obtained in solution and on painted samples of known composition to be compared and correlated, highlighting that the fluorescence of the lake within paint layers is affected by both self-absorption and aggregation phenomena. This approach has been successfully applied on a painting by G. Vasari for the noninvasive identification of carmine lake. The results reported here emphasize the necessity of taking physical phenomena into account in the interpretation of the fluorescence spectra for a proper and reliable characterization and identification of painting materials in works of art.

Ultraviolet-induced fluorescence spectroscopy is a commonly used technique for the characterization and identification of painting materials, such as organic binders and colorants. Its interpretation is strictly connected to both the experimental setup and an understanding of the physical and chemical interactions among materials in paint layers, which are commonly composed of a fluorescent organic binder and a pigment. When irradiated with ultraviolet radiation, the light emitted by fluorophores present in the organic binder undergoes several types of interactions, in particular scattering and absorption by neighboring pigmented particles and auto-absorption. As a result of scattering and absorption phenomena, the emission spectrum is deformed according to the physical properties of the surrounding pigmented particles. This can lead to shifts of the emission maxima and/or to the formation of apparent new emission bands. The extent of the modifications to the emission spectra, caused by auto-absorption and selective absorption phenomena, may lead to the erroneous characterization or identification of the fluorescent materials. As a consequence, the interpretation of the emission signal can be greatly compromised. A correction based on the Kubelka-Munk theory is proposed to evaluate the extent of the spectral distortion and is assessed on modern replicas of wall paintings of known composition. Although the model cannot be applied to all cases, qualitative distinctions between real and apparent emissions are achieved.

The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

Although digital multispectral imaging-particularly ultraviolet-induced fluorescence imaging-is a very common examination tool, its interpretation remains fraught with difficulties. Interpretation is strongly dependent on the capture methodology, requires an understanding of the physical and chemical characteristics and interactions among materials in artworks and is affected by data-analysis procedures. The present research, which began with imaging of paint materials of known composition and proceeded to a range of representative case studies, confirmed that fluorescence emissions by painting materials-such as organic binders or colorants-are generally severely affected by the presence of absorbing non-fluorescing materials, such as inorganic pigments. Application of a mathematical model based on the Kubelka-Munk theory, resulted in the possibility of distinguishing between real and apparent fluorescence emissions. Real emissions correspond to the presence of materials which de facto exhibit fluorescent properties (typically organic binders and colorants), while apparent emissions relate to the optical interactions among fluorescent materials and surrounding non-fluorescent materials (typically inorganic pigments). Correction for the 'pigment-binder interaction' can also provide useful information on the presence of materials whose fluorescence is almost obliterated by absorbing pigmented particles. Therefore, this image-processing methodology can be used to characterise and reveal emissions that are dimmed or altered by re-absorption. This capacity to reveal the presence of weakly fluorescing emitters has important conservation implications and informs the sampling strategy for further analytical investigations. Examples of the application of this data analysis to images made at the Grotto Site in Dunhuang, China, and at the British Museum are presented.

Cuprorivaite (CaCuSi(4)O(10), also known as Egyptian blue) exhibits an exceptionally high emission quantum efficiency in the near-infrared region (lambda(max) = 910 nm, Phi(EM) = 10.5%) and a long excited state lifetime (107 mus); these properties make it appealing for several applications in the fields of biomedical analysis, telecommunications and lasers.