Autori: M. Saleh, L. Bonizzoni, J. Orsilli, S. Samela, M. Gargano, S. Gallo, A. Galli

Informazioni pubblicazione: Microchemical Journal 154 (2020)

Abstract

Lapis lazuli use stretches back more than 6500 years; ancient civilizations of Mesopotamia, Egypt, China, Greece, and Rome treasured and prized it. Afghanistan has been the oldest source for this stone, while Chile, Canada, Russia and a few other countries have been reported as sources for raw material in more recent times; the rarity of historical mines surely represents a positive aspect for the provenance clue of artefacts. Lapis lazuli is a rock consisting mainly of lazurite, to which it owes the blue colour, calcite and pyrite. Other constituents may be present, related to the different mines. In the present work, we apply the principles of Radio-luminescence (RL) exploiting as radiation source the X-ray tube of a portable commercial X-Ray Fluorescence spectrometer; in this way, X-Ray Fluorescence spectra (XRF) can be simultaneously acquired to have a larger set of data. To highlight the instrumental experimental differences, we refer to the portable set up as X-Ray Luminescence (XRL), as suggested by recent literature. We thus looked for the possibility of applying a wieldy, low cost and non-destructive method that could fit also to precious objects, based on the join use of XRF and XRL. We performed analyses on raw lapis lazuli stones from five different provenances, both historical and modern, and on four sets of unknown origin carved polished stones, to test our methods on real artefacts. We focalised on a limited number of samples to concentrate on the statistical treatment of spectra obtained, so to get a synergic response of the two applied techniques. We were able to obtain a clear distinction for the different classified provenances and could speculate those of unknown samples.

Autori: M. Saleh, L. Bonizzoni, J. Orsilli, S. Samela, M. Gargano, S. Gallo, A. Galli

Informazioni pubblicazione: Microchemical Journal 154 (2020)

Abstract

Lapis lazuli use stretches back more than 6500 years; ancient civilizations of Mesopotamia, Egypt, China, Greece, and Rome treasured and prized it. Afghanistan has been the oldest source for this stone, while Chile, Canada, Russia and a few other countries have been reported as sources for raw material in more recent times; the rarity of historical mines surely represents a positive aspect for the provenance clue of artefacts. Lapis lazuli is a rock consisting mainly of lazurite, to which it owes the blue colour, calcite and pyrite. Other constituents may be present, related to the different mines. In the present work, we apply the principles of Radio-luminescence (RL) exploiting as radiation source the X-ray tube of a portable commercial X-Ray Fluorescence spectrometer; in this way, X-Ray Fluorescence spectra (XRF) can be simultaneously acquired to have a larger set of data. To highlight the instrumental experimental differences, we refer to the portable set up as X-Ray Luminescence (XRL), as suggested by recent literature. We thus looked for the possibility of applying a wieldy, low cost and non-destructive method that could fit also to precious objects, based on the join use of XRF and XRL. We performed analyses on raw lapis lazuli stones from five different provenances, both historical and modern, and on four sets of unknown origin carved polished stones, to test our methods on real artefacts. We focalised on a limited number of samples to concentrate on the statistical treatment of spectra obtained, so to get a synergic response of the two applied techniques. We were able to obtain a clear distinction for the different classified provenances and could speculate those of unknown samples.

Autori: A. Galli, M. Caccia, L. Bonizzoni, M. Gargano, N. Ludwig, G. Poldi, M. Martini 

Informazioni pubblicazione: Microchemical Journal, Volume 155, June 2020

Abstract

In the context of paintings characterization, X-Ray Fluorescence (XRF) combined with Fibre Optics Reflectance Spectroscopy (FORS) is a well-known methodology. The latter allows to classify the pigments constituting the external layers (few microns) of the painting while the former provides the fingerprint of the main chemical elements present in almost all layers (tens of microns) of the sample. The synergetic application of XRF and FORS is a key turn for non-invasive scientific analysis of works of art since it exhaustively describes the pigments employed by the masters and supplies a first insight into their distribution on the panels. In this scenario, Optical Microscopy (OM) applied directly on the painting surface, without any type of sampling, is traditionally deemed as a descriptive tool for showing microscopic features such as craquelure, brushstrokes or painting material distribution. It can be eventually expendable as a qualitative help during the discussion of spectroscopic data, but not considered fundamental. Nonetheless, the application of image processing protocols can make OM a concrete support for the characterization of paintings. In this work a new image analysis strategy has been introduced, its potential has been demonstrated studying different flesh tones from the panel “The Holy Family with St. Anne and the young St. John” by Bernardino Luini (Pinacoteca Ambrosiana Collection of Milan) and, finally, it has been discussed how OM could quantitatively complete XRF and FORS analysis. The results show that optical microscopy, other than provide a glance of the investigated surface spots, effectively integrates the description given by the spectroscopic techniques and, properly managed, can be a useful resource for solving ambiguous cases.

Autori:  N. Ludwig, M. Gargano, S. Gallo, P. Arosio, F. Orsini, L. Bonizzoni, J. Melada, M. Avolio

Informazioni pubblicazione: Measurement 151 (2020)

Abstract

A promising approach in oncology consists in combining Radiation Therapy (RT) with Magnetic Fluid Hyperthermia (MFH). Modern day RT takes advantage by imaging techniques able to provide information about the correct patient set-up, target position and movement during the treatments. For these purposes, gold fiducial markers, implanted into the tumors, or in their proximity, are used in the so-called Image–Guided Radiation Therapy (IGRT). In this study, hyperthermia produced by different gold fiducial markers under the application of an alternating magnetic field in the typical conditions used in Magnetic Fluid Hyperthermia (MFH) clinical trials was investigated. The temperature increase of different types of gold fiducial markers and of tissue mimicking hydrogel phantoms containing the fiducials were measured during the magnetic stimulation by means of a high-resolution thermal camera and a fiber optic temperature sensor. The results demonstrated that, within few tens of seconds after the start of the magnetic stimulation, the gold fiducial markers might reach temperatures higher than 70 °C. Local increases of the hydrogel temperature to values higher than 45 °C were also measured. These evidences highlight the need to evaluate carefully the presence and location of gold fiducial markers in patients undergoing combined IGRT and MFH treatments in order to prevent any thermal ablation of health tissues surrounding the markers.

Autori: M. Gargano, L. Bonizzoni, E. Grifoni, J. Melada, V.Guglielmi, S. Bruni, N. Ludwig

Informazioni pubblicazione: Journal of Cultural Heritage (2020)

Autori: F. Micheletti, J. Orsilli, J. Melada, M. Gargano, N. Ludwig, L. Bonizzoni

Informazioni pubblicazione: Microchemical Journal 153 (2020)

Abstract

The process of degradation of archaeological glass subjected to centuries of burial can be of great relevance: typical consequence of degradation in the original vitreous material is rainbow-like iridescence due to chemical alteration of surface layers, salts formation and ion migration. The research presented in this paper is focused on the study of a collection of Roman glass (I – II century A.D.) held by the Museo Civico Etnografico Archeologico Fanchini of Oleggio, Italy. Chemical characterization (namely flux, chromophores and opacifiers determination) has been performed by a combination of X-Ray Fluorescence (XRF) and Fibre Optics Reflectance Spectroscopy (FORS) in the UV–Vis-NIR region. Conservation conditions have been studied and degraded areas have been mapped through Infrared thermography (IRT). IRT is a non-invasive method typically used to measure the apparent temperature of objects and represent it as pseudo-colour images. In the present work, we demonstrate the feasibility of IRT for identifying and mapping glass substrate defects due to ageing of glass, assuming that they may be considered as thermal anomalies. Thermogram sequences have been processed by high order statistical analysis, which is particularly suitable since it is based on automated processes where the output is a single representative image. The use of a thermal camera allows furthermore to perform remote analysis in areas hardly reachable in a fast and effective way.

Autori: E. Grifoni, B. Campanella, S. Legnaioli, G. Lorenzetti, L. Marras, S. Pagnotta, F. Poggialini, V. Palleschi, E. Salerno, A. Tonazzini

Informazioni pubblicazione: Journal of Computing and Cultural Heritage, 12 (2), (2019).

Abstract

In this article, we present a new method for the analysis of visible/Infrared multispectral sets producing chromatically faithful false-color images, which maintain a good readability of the information contained in the non-visible Infrared band. Examples of the application of this technique are given on the multispectral images acquired on the Pietà of Santa Croce of Agnolo Bronzino (1569, Florence) and on the analysis and visualization of the multispectral data obtained on Etruscan mural paintings (Tomb of the Monkey, Siena, Italy, V century B.C.). The fidelity of the chromatic appearance of the resulting images, coupled to the effective visualization of the information contained in the Infrared band, opens interesting perspectives for the use of the method for visualization and presentation of the results of multispectral analysis in Cultural Heritage diffusion, research, and diagnostics.

Autori: L. Idjouadiene, T. A. Mostefaoui, H. Djermoune, L. Bonizzoni 

Informazioni pubblicazione: X‐Ray Spectrometry 2019;1–8

Abstract

The North African regions boast a multimillenary tradition of pottery production that represents a decisive progress in all societies. In this paper, we present the analysis of several fragments of pottery dating from the Middle Ages and collected in the archaeological site of Gouraya in Béjaïa (Algeria). Energy‐dispersive X‐ray fluorescence measurements were performed to obtain the elemental composition of the clays and to attempt a classification of the samples through multivariate analysis methods, connecting them to the archaeological information about the sites. Hierarchical clusters analysis (HCA) identified two possible different groups, related to different production sites, even if only one source of clay seem to be used, consistently with the geological contest. Based on the results, a tentative provenance interpretation could be proposed on historical bases. We put in place a strategy that made it possible to perform provenance studies respecting sample integrity as we aim to extend our research also to integer and well‐preserved object from museum, to create a database for Algerian production of in the Middle Ages.

Autori: M. Gargano, A. Galli, L. Bonizzoni, R. Alberti, N. Aresi, M. Caccia, I. Castiglioni, M. Interlenghi, C. Salvatore, N. Ludwig, M. Martini

Informazioni pubblicazione: Journal of Cultural Heritage 36 (2019) 255–263

Abstract

God the Father with Angels (about 1330, tempera on panel) by Giotto is the Gable of the altarpiece of Baroncelli Chapel in the church of Santa Croce in Florence. Very little is known about its history since the separation from the so-called Baroncelli Polyptych. Now at the San Diego Museum of Art, the Gable had never been studied by means of scientific methods before our team took the opportunity to during the exhibition “Giotto, l’Italia” held in Milan. Exploiting the integration of different knowledge, technologies and resources of our team, we were able to provide data for understanding the organizational model of Giotto’s workshop performing non-invasive analyses with portable instruments during closing hours of exhibition (four diagnostic campaigns, six hours of work/campaign, no interruption of the exhibition). The achieved results confirm the painting technique based on different layers of pigments, a technique already used by Giotto. Combining the effectiveness of scanning MA-XRF with the responsive of IR reflectography and IR false colour, we moved step by step toward the discovery of Giotto’s palette for the flesh tones in God the Father with Angels. FORS and XRF single point analyses were performed on some selected areas too. The IR reflectography results support the hypothesis of a detailed underdrawing with both thin and flat brushstrokes. By applying image-processing algorithms to the collected reflectograms, we obtained quantitative objective measures supporting the hypothesis that a guide could have been used in the realization of human figures; this means the use of sketches for the face of “God the Father” and for the faces of angels.

Autori: N. Ludwig, J. Orsilli, L. Bonizzoni, M. Gargano

Informazioni pubblicazione: Archaeological and Anthropological Sciences (2019)

Abstract

The use of non-invasive analytical techniques on cultural heritage objects usually faces the insurmountable limit of dealing with artworks subjected to more restorations. For painted surfaces, imaging techniques, such as infrared photography (NIR) and ultraviolet-induced visible fluorescence (UVIVF), allow to distinguish areas with different kind and period of interventions. This paper presents the application of such techniques on two wooden coffins of the 21st Dynasty with a complex restoration history, the analytical inspections deal with the issues occurring in the reconstruction of a fluorescence map that is influenced by on both the use of non-original pigments and the presence of protective varnishes. In uncontrolled laboratory conditions, the possibility to associate quantitatively and univocally the luminance recorded by the camera with a certain level of fluorescence can be very difficult. An algorithm has been developed to obtain a map with an evident relationship between fluorescence and diagnostic information. First, the pixels of the fluorescent areas presenting different reflectance in the visible image have been used to equalize the visible image. Then, the ratio of the UVIVF image to the equalized image has been calculated, highlighting the low and non-fluorescent areas. After the thresholding and the segmentation of the UVIVF image, the masks obtained have been overlaid on the NIR images to merge and to map the areas with supposed similar restoration materials. The results illustrated in this work are followed by a punctual spectroscopic campaign, where the information on the imaging analysis is linked to and completed by the study of the chemical compounds in the coffins.

Autori: A. Galli, M. Gargano, L. Bonizzoni, C. Giorgione, N. Ludwig, F. Maspero, M. Orlandi, L. Zoia, M.Martini

Informazioni pubblicazione: Microchemical Journal 138 (2018) 408–417

Abstract

Leonardo’s Codex Atlanticus depicted a detailed drawing for an improved wooden canal lock to control the water flow in Milan’s canal system. Museo Nazionale della Scienza e della Tecnologia “Leonardo da Vinci” in Milan has been conserving two pairs of canal gates in its storage for more than fifty years, until a complete and multidisciplinary study was launched to deeply examine one of the pairs. Both historical and scientific research teams joined in their efforts. While historical research has recreated the provenience of the gates until their arrival at the Museum, the scientific analyses were a new opportunity to help the reconstruction and characterization of the canal gates’ history, enlightening the construction technique, the structural modifications over time and the conservation conditions. The multidisciplinary investigations involved radiographic analyses, 14C dating and the chemical characterization of the wood present in the gates. Through the radiographic analyses, it was possible to show the structure of the gates, the joints and the position of the metal components. Eighteen micro-samples were collected on selected areas of the gates and provided interesting results: artifacts dating the results span over four centuries. Furthermore, the degradation of the wood was studied by estimating the amount of lignin and holocellulose, and the distribution of their molecular weights.

Autori: E. Grifoni, S. Legnaioli, G. Lorenzetti, P. Nieri, S. Pagnotta, F. Poggialini, B. Campanella, V. Palleschi

Informazioni pubblicazione: Journal of Cultural Heritage (2018)

Abstract

3D multi–band/multi-spectral reconstruction is a technique, which allows the use of images taken in different spectral bands for the reconstruction of spectrally-resolved 3D models of paintings. In this work, we propose a procedure for constructing and comparing 3D multi–band models obtained starting from a variety of input data (RGB and IR images, UV-induced fluorescence images, etc.) and/or acquired with different instruments. The procedure has been tested on two case studies, with the aim to highlight the critical issues associated to the specificities of the subject and of the environmental constrains: a 14th century panel painting signed by Barnaba from Modena, preserved at the Museum of San Matteo in Pisa, Italy and a 15th century panel painting preserved at the Regional Gallery of Palazzo Bellomo in Syracuse, Italy. RGB, IR and UV–VIS fluorescence models obtained with a conventional digital camera (RGB and UV) and a multisband camera (IR) were realized and compared, for revealing differences at sub-millimeter level.

Autori: G. Senesi, B. Campanella, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, F. Poggialini, V. Palleschi, O. De Pascale

Informazioni pubblicazione: Spectrochimica Acta PArt B, 143, pp. 91-97 (2018)

Abstract

The present work aims to evaluate the alteration conditions of historical limestone rocks exposed to urban environment using the Laser-Induced Breakdown Spectroscopy (LIBS) technique. The approach proposed is based on the microscale three dimensional (3D) compositional imaging of the sample through double–pulse micro–Laser–Induced Breakdown Spectroscopy (DP-μLIBS) in conjunction with optical microscopy. DP-μLIBS allows to perform a quick and detailed in-depth analysis of the composition of the weathered artifact by creating a ‘virtual thin section’ (VTS) of the sample which can estimate the extent of the alteration processes occurred at the limestone surface. The DP-μLIBS analysis of these thin sections showed a reduction with depth of the elements (mainly Fe, Si and Na) originating from atmospheric dust, particulate deposition and the surrounding environment (due to the proximity of the sea), whereas, the LIBS signal of Ca increased in intensity from the black crust to the limestone underneath.

Autori: S. Pagnotta, M. Lezzerini, B. Campanella, G. Gallello, E. Grifoni, S. Legnaioli, G. Lorenzetti, F. Poggialini, S. Raneri, A. Safi, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta PArt B, 146, pp. 9-15, (2018)

Abstract

In this work, a fast method for obtaining a quantitative elemental mapping of highly inhomogeneous samples by μ-LIBS maps is proposed. The method, transportable and cheap, allows the analysis of large maps through the use of a Self-Organizing Map clustering method coupled to Calibration-Free LIBS for quantification of cluster prototypes. The method proposed has been verified on heterogeneous materials such historical lime mortars but it can be easily applied to a larger class of inhomogeneous materials for very different applications (modern building materials, biological samples, industrial materials, etc.).

Autori: F. Poggialini, B. Campanella, S. Giannarelli, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, A. Safi, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta PArt B, 141, pp. 53-58, (2018)

Abstract

When compared to other analytical techniques, LIBS shows relatively low precision and, generally, high Limits of Detection (LODs). Until recently, the attempts in improving the LIBS performances have been based on the use of more stable/powerful lasers, high sensitivity detectors or controlled environmental parameters. This can hinder the competitiveness of LIBS by increasing the instrumental setup cost and the difficulty of operation. Sample treatment has proved to be a viable and simple way to increase the LIBS signal; in particular, the Nanoparticle-Enhanced Laser Induced Breakdown Spectroscopy (NELIBS) methodology uses a deposition of metal nanoparticles on the sample to greatly increase the emission of the LIBS plasma. In this work, we used a simple, fast, “green” and low-cost method to synthetize silver nanoparticles by using coffee extract as reducing agents for a silver nitrate solution. This allowed us to obtain nanoparticles of about 25 nm in diameter. We then explored the application of such nanoparticles to the NELIBS analysis of metallic samples with a mobile LIBS instrument. By adjusting the laser parameters and optimizing the sample preparation procedure, we obtained a NELIBS signal that is 4 times the LIBS one. This showed the potential of green-synthetized nanoparticle for NELIBS applications and suggests the possibility of an in-situ application of the technique.

Autori: I. Degano, B. Campanella, S. Legnaioli, E. Grifoni, G. Lorenzetti, S. Pagnotta, F. Poggialini, V. Palleschi

Informazioni pubblicazione: Microchemical Journal, 139, pp. 230-235, (2018)

Abstract

The identification of both the organic and inorganic fraction of dyes and pigments is fundamental for their complete characterization and to assess the technologies used in their production. In this work, the feasibility of determining metallic elements used as mordant for dyed textiles was tested using Laser-Induced Breakdown Spectrometry (LIBS) in combination with liquid micro-extraction. Both reference laboratory-dyed and historic textiles were analysed in this study. Samples were first analysed without any preparation. Then, the chromophores-containing molecules were separated using a sample preparation procedure based on aqueous hydrolysis, and analysed by high-pressure liquid chromatography coupled with a diode array detector. The same extracts, containing also the inorganic fraction, were analysed by Surface-Enhanced Laser-Induced Breakdown Spectroscopy (SENLIBS) after drying on a solid substrate.
Compared to the direct analysis, the SENLIBS method improved the sensitivity of the measurements. The procedure presented here allowed for the characterization of both organic and inorganic fraction of a single textile micro sample, thus avoiding further sampling.

Autori: S. Pagnotta, S. Legnaioli, B. Campanella, E. Grifoni, M. Lezzerini, G. Lorenzetti, V. Palleschi, F. Poggialini, S. Raneri

Informazioni pubblicazione: Mediterranean Archaeology and Archaeometry 18(5), pp. 171-178 (2018)

Abstract

In the study of ancient pottery, thin section analysis represents the basic approach to study mineralogical and petrografic features in order to obtain preliminary information about the production technology and origin of archaeological ceramics. However, even if thin section analysis allows investigating the textural and structural characteristics of potteries, peculiar features related to clay paste and temper composition, as well as provenance issues, can be detailed addressed only by quantitative mineralogical and chemical studies. In the realization of thin sections, a negative face is always produced, similar to the thin section itself; these remains can be used for additional analyses, such as high spatial resolution micro-chemical studies using, for example, a micro-laser induced breakdown spectroscopy (LIBS) scanner. LIBS is a spectroscopic technique that, exploiting the laser radiation, is able to bring into the plasma state micrometric portions of the sample, and to analyse its content through the study of the optical emission of the plasma itself. Unlike other techniques, LIBS can detect and quantify also light elements such as aluminium and magnesium. Images produced by the micro-LIBS instrument show the spatial distribution of the chemical elements within a portion of the sample, which may have dimensions from a few hundred microns up to several centimeters. The combination of these images with algorithms derived from image processing techniques may return interesting information and supporting data to in-depth investigate pottery components detected by optical microscopy observations. In this work, we present the results of an experimental study performed on thin-section negatives with different grain size, surface treatments and aggregates, coming from some Neolithic Italian sites, exploring the potential of the LIBS method in micro-chemical studies of ancient potsherds.

Autori: B. Campanella, S. Legnaioli, E. Grifoni, M. Hidalgo Núñez, G. Lorenzetti, S. Pagnotta, L. RipollSeguer, F. Poggialini, V. Palleschi

Informazioni pubblicazione: Journal of Cultural Heritage, 33, pp. 208-212, (2018)

Abstract

The chemical characterization of paint material is paramount for the understanding of painting techniques, provenance studies and for assessing conservation strategies. In particular, the chemical characterization of both the organic and inorganic fraction of lakes is fundamental to assess the technologies used in their production. In this short note, we present a pilot study by comparing several micro-destructive and non-destructive methods for the comprehensive characterization of the organic and inorganic fraction of reference madder lakes. In the final procedure, the chromophores-containing molecules were separated using a sample preparation procedure based on acid hydrolysis and solvent extraction, and analysed by high-pressure liquid chromatography with UV-Vis detector (HPLC-UV/Vis). Laser induced breakdown spectroscopy (LIBS) and X-Ray Fluorescence (XRF) were used for the study of the elemental composition. Multispectral Imaging was also applied in order to evaluate its potentialities to distinguish amongst different red lakes. The final multi-technique method allowed for the characterization of both organic and inorganic fraction from the same lake micro sample.

Autori: A. Safi, B. Campanella, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, F. Poggialini, L. RipollSeguer, M. Hidalgo, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta PArt B, 144, pp. 46-54, (2018)

Abstract

The introduction of multivariate calibration curve approach in Laser-Induced Breakdown Spectroscopy (LIBS) quantitative analysis has led to a general improvement of the LIBS analytical performances, since a multivariate approach allows to exploit the redundancy of elemental information that are typically present in a LIBS spectrum. Software packages implementing multivariate methods are available in the most diffused commercial and open source analytical programs; in most of the cases, the multivariate algorithms are robust against noise and operate in unsupervised mode. The reverse of the coin of the availability and ease of use of such packages is the (perceived) difficulty in assessing the reliability of the results obtained which often leads to the consideration of the multivariate algorithms as ‘black boxes’ whose inner mechanism is supposed to remain hidden to the user. In this paper, we will discuss the dangers of a ‘black box’ approach in LIBS multivariate analysis, and will discuss how to overcome them using the chemical-physical knowledge that is at the base of any LIBS quantitative analysis.

Autori: L. Bonizzoni, S. Bruni, M. Gargano, V. Guglielmi, C. Zaffino, A. Pezzotta, A. Pilato, T. Auricchio, L. Delvaux, N. Ludwig

Informazioni pubblicazione: Microchemical Journal 138 (2018) 122–131

Abstract

The Royal Museums of Art and History of Brussels holds six coffins of the 21st Dynasty coming from a single discovery, the Second Cachette of Deir el-Bahari (Bab el-Gasus) (L. Delvaux & I. Therasse, Sarcophages. Sous les étoiles de Nout, Bruxelles 2015, p. 83–111). Since their discovery in 1891, their rich decorations have been subjected to deep manipulations during the years. In 2014, six coffins and four mummy-covers, the entire collection of the 21st Dynasty, were entrusted to the European Institute of Restoration for their diagnosis and restoration. In 2015, one compete coffin (composed by the external coffin, the internal one and the mummy cover) were the subject of a first targeted diagnostic campaign at the European Institute of Restoration laboratories.

On this occasion, non-invasive in situ analyses have been performed on more than one hundred measuring points of the complete object, considering the five decorated parts (the two wooden anthropoid coffins composed by lid and base and the mummy-cover) showing both different technical features and pictorial materials.

After a preliminary phase of analysis by imaging techniques such as Infrared Reflectography and Visible Fluorescence induced by UV, the pigments and binders were examined exploiting the synergy between four complementary techniques, namely EDXRF (energy dispersive X-ray fluorescence), FORS (fibre optics reflectance spectroscopy), reflection FTIR (Fourier transform infrared spectroscopy) and micro-Raman spectroscopy. The application of techniques with different penetration depths on more than one hundred points allowed to detect the stratigraphic sequences without sampling, opening to the interesting application to off-limits masterpieces.

Based on imaging techniques, the painted surfaces showed areas with different features: dark areas with no UV fluorescence and low reflectance in IR, bright UV fluorescence and high IR reflectance (wavelength > 700 nm) and low-intensity UV fluorescence again with high reflectance in the infrared region. Such zones can be linked to the presence or absence of marker chemical elements (for instance Ba or Ti) or compounds that give hints about the presence and the period of the restorations. In these areas, an overlapping of a modern layer on the ancient and original one is the most probable current status of the pictorial stratigraphy.

Original identified pigments include Egyptian blue, copper-based green, calcium carbonate and Red Ochre on an underlying Orpiment yellow layer. In the areas considered as already restored in the past on the bases of the analytical results, we find Azurite, Prussian blue, Egyptian Blue, Vermillion, Red Ochre, Chrome Red, Chrome Green, copper-based green, Zinc Yellow and Lead White. A layer composed of a natural resin was also detected by in-situ FTIR measurements; the resin could be more precisely identified as mastic by laboratory analyses.

Autori: L. Angeli, S. Legnaioli, C. Fabbri, E. Grifoni, G. Lorenzetti, J. Guilaine, V. Palleschi, G. Radi

Informazioni pubblicazione: Microchemical Journal, 137, pp. 174-180, (2017)

Abstract

During the Middle Neolithic (between 5000 and 4500 cal. BCE) the Serra d’Alto Culture was particularly widespread in Matera’s territory and in Apulia region. Serra d’Alto pottery wares consist both of a very fine yellow paste—called figuline—decorated with patterns in black, and of a medium/coarse paste.

In this paper, the X-ray Fluorescence (XRF) analyses of 102 samples of black painted decorated figuline pottery are reported. We analyzed sherds from six archaeological sites of Matera’s area: Serra d’Alto, Trasano, Setteponti, Tirlecchia and Pipistrelli’s cave, and Funeraria cave.

The results show that a black pigment based on manganese has been used for the decoration of each of the Serra d’Alto samples. The exclusive presence of this material suggests a deliberate technological choice and defines a regular characteristic of Serra d’Alto pottery manufacturing.

This study is part of an interdisciplinary project on painted pottery in the central and southern Italy, from Early to the Middle Neolithic period.

Autori: B. Campanella, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, F. Sorrentino, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta – PArt B Atomic Spectroscopy, 134, pp. 52-57, (2017)

Abstract

Every year throughout the world N50 million vehicles reach the end of their life, producing millions of tons of automotive waste. The current strategies for the separation of the non-ferrous waste fraction, contain mainly aluminum, magnesium, zinc and copper alloys, involve high investment and operational costs, and pose environmental concerns. The European project SHREDDERSORT, in which our research group was actively involved, aimed to overcome this issue by developing a new dry sorting technology for the shredding of non-ferrous automotive wastes. This work represents one step of the complex SHREDDERSORT project, dedicated to the development of a strategy based on Laser Induced Breakdown Spectroscopy (LIBS) for the sorting of light alloys.
LIBS was here applied in laboratory for the analysis of stationary aluminum shredder samples. To process the LIBS spectra a methodological approach based on artificial neural networks was used. Although separation could in principle be based on simple emission line ratios, the neural networks approach enables more reproducible results, which can accommodate the unavoidable signal variations due to the low intrinsic reproducibility of the LIBS systems. The neural network separated samples into different clusters and estimates their elemental
concentrations.

Autori: F. Bredice, P. Pacheco MArtinez, R. Sarmiento Mercado, C. Sánchez-Aké, M. Villagrán-Muniz, J.B. Sirven, M. El Rakwe, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, V. Palleschi 

Informazioni pubblicazione: Spectrochimica Acta – PArt B Atomic Spectroscopy, 135, pp. 48-53, (2017)

Abstract

In this paper we present the application of Independent Component Analysis to a set of time-resolved LIBS spectra, acquired on a brass sample at different delay times. The decomposition of the LIBS spectra in few Independent Components with a given temporal evolution is then exploited for obtaining the temporal evolution of the plasma electron temperature, through the application of the three-dimensional Boltzmann plot method recently proposed by the authors. This method allows the determination of the electron temperature temporal evolution without any knowledge of the spectral parameters (transition probability, degeneracy of the levels, etc.…) of the emitting lines. Only the knowledge of the energy of the upper level of the transition is required. The reduction of the LIBS spectral dataset to few Independent Components and associated proportions, further simplifies the determination of the plasma electron temperature temporal evolution, since the intensity of the emission lines does not need to be calculated. The results obtained are compared with the ones obtained using classical two-dimensional Boltzmann plot approach.

Autori: A. Galli, M. Caccia, R. Alberti, L. Bonizzoni, N. Aresi, T. Frizzi, L. Bombelli, M. Gironda, M. Martini

Informazioni pubblicazione: X‐Ray Spectrometry 2017, 46, 435–441

Abstract

Elemental analysis, and in particular stratigraphic distribution of elements themselves, is a fundamental method to address the composition of materials, but its nature, often invasive, crashes with the necessity of avoiding artefacts’ damage when dealing with Cultural Heritage objects. In fact, when work of art are involved, sampling is often forbidden, and transferring an artistic artefact to equipped laboratories is a not negligible issue. The skill to employ in situ non‐destructive and non‐invasive analytical method is essential. In this scenario, portable X‐ray fluorescence (p‐XRF) has become one of the most employed techniques due to the development of adaptable and open architecture instruments. In this paper, we show a new data analysis protocol and its application to XRF data acquired from a work by Giotto never studied before: ‘God the Father with Angels’ (ca. 1330, San Diego Museum of Art). The measurements have been performed in situ during the closing time of the exhibition ‘Giotto, l’Italia’ (Milano Palazzo Reale – 2 September 2015/10 January 2016). Combining the effectiveness of scanning p‐XRF with the responsive of image spectroscopic analysis, we move step by step toward the discovery of Giotto’s palette for the flesh tones in God the Father with Angels; our method allows to argue the stratigraphy of the painting without complementary measurements and, at the same time, provides a sequential and smart representation of complex data.

Autori: E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: European Journal of Science and Theology 13(2), pp.127-134, (2017)

Abstract

In recent years, the documentary survey of Cultural Heritage (CH) has experienced an enormous evolution boost, thanks to the implementation and optimization of Digital Photogrammetry. In this paper we present the results obtained by applying a new method for the 3D reconstruction of multispectral surfaces. Reality-Based 3D Modelling (RBM) coupled with Multispectral Imaging (MSI) can be a valid tool able to analytically point out and to enrich with new, revealing dimensions any „text to be queried‟. The method is applied to the study of a Renaissance painting conserved at the Civic Museum of Sansepolcro (Arezzo, Italy), depicting the Plague of Sansepolcro in 1523. The
comparison between the 3D profiles obtained at different depths under the surface evidences the profile changes that occur in the layers under the surface. All the analysis was performed using inexpensive or even open source software; the availability of this software, together with the great flexibility in the experimental setup and the very short time needed for the acquisition of the images, suggests the application of the proposed method on a routine basis in the multispectral analysis of paintings, to obtain a better understanding on the profiles of the different layers under the painted surface.

Autori: L. Bonizzoni, M. Gargano, N. Ludwig, M. Martini, A. Galli

Informazioni pubblicazione: Applied Spectroscopy 2017, Vol. 71(8) 1915–1926.

Abstract

Non-invasive, portable analytical techniques are becoming increasingly widespread for the study and conservation in the field of cultural heritage, proving that a good data handling, supported by a deep knowledge of the techniques themselves, and the right synergy can give surprisingly substantial results when using portable but reliable instrumentation. In this work, pigment characterization was carried out on 21 Leonardesque paintings applying in situ X-ray fluorescence (XRF) and fiber optic reflection spectroscopy (FORS) analyses. In-depth data evaluation allowed to get information on the color palette and the painting technique of the different artists and workshops . Particular attention was paid to green pigments (for which a deeper study of possible pigments and alterations was performed with FORS analyses), flesh tones (for which a comparison with available data from cross-sections was made), and ground preparation.

Autori: S. Pagnotta, M. Lezzerini, L. Ripoll-Seguer, M. Hidalgo, E. Grifoni, S. Legnaioli, G. Lorenzetti, F. Poggialini, V. Palleschi

Informazioni pubblicazione: Applied Spectroscopy, 71(4), pp. 721-727, (2017)

Abstract

The laser-induced breakdown spectroscopy (LIBS) technique was used for analyzing the composition of an ancient Roman mortar (5th century A.D.), exploiting an experimental setup which allows the determination of the compositions of binder and aggregate in few minutes, without the need for sample treatment. Four thousand LIBS spectra were acquired from an area of 10 mm², with a 50 µm lateral resolution. The elements of interest in the mortar sample (H, C, O, Na, Mg, Al, Si, K, Ca, Ti, Mn, Fe) were detected and mapped. The collected data graphically shown as compositional images were interpreted using different statistical approaches for the determination of the chemical composition of the binder and aggregate fraction. The methods of false color imaging, blind separation, and self-organizing maps were applied and their results are discussed in this paper. In particular, the method based on the use of self-organizing maps gives well interpretable results in very short times, without any reduction in the dimensionality of the system.

Autori: C. Arias, S. Bani, F. Catalli, G. Lorenzetti, E. Grifoni, S. Legnaioli, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Applied Spectroscopy, 71(5), pp. 817-822 (2017)

Abstract

The “Monetiere” of Florence hosts the most important collection of Etruscan coins in the world. In the framework of the longstanding collaboration between the Monetiere and the Applied Laser and Spectroscopy Laboratory in Pisa, the Etruscan gold coin collection of the museum was studied. The measurements were performed at the Monetiere, using a portable energy-dispersive X-ray fluorescence (XRF) instrument. The quantitative determination of the gold alloys used for the realization of the coins was obtained applying the fundamental parameters method to the XRF spectra; as a result, using the self-organizing maps method, we were able to classify the coins in four main groups. The main parameter determining the classification is the quantity of silver in the alloy. The results obtained shed some light about the origin of the coins under study.

Autori: L. Bonizzoni, S. Bruni, G. Fanti, P. Tiberio, C. Zaffino

Informazioni pubblicazione: Microchemical Journal 125 (2016) 69–74

Abstract

Flax fibre (Linum usitatissimum) is probably the earliest textile material and holds a great archaeological interest. The possibility to define a connection between ageing and molecular characteristics is thus a concrete purpose aiming to help indirect dating. In the present work, such possibility was investigated by spectroscopic techniques that allow to examine micro-sized samples and are moreover non-destructive towards the sample itself, an important requirement when precious and ancient artefacts are analysed. Confocal micro-Raman spectroscopy and laser-excited micro-fluorescence spectroscopy were applied to 23 micrometric fibres from historical linens (dating from about 3000 BC to the XVII cent.) and 11 crude or treated modern fibres. The intensity ratio between Raman bands at 1121 and 1096 cm^− 1, already suggested in the literature as a possible signature for ageing, was systematically evaluated after baseline correction, showing that modern samples exhibit a quite constant ratio value of 0.85 ± 0.05 which diminishes up to 0.7 if the linen fibre is heated or bleached. Fibres form archaeological linen show instead a lower value for this ratio, that decreases to about 0.5 depending both on age and on conservation conditions. Laser-excited fluorescence spectra were also collected from the fibres, yielding a Pearson correlation value of about 0.7 between the intensity of the fluorescence emission and the age of the flax samples. Irregularity in the trend is mainly due to the possible influence of alien features such as contamination from organic substances.

Autori: E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta – PArt B Atomic Spectroscopy, 118(1), pp. 40-44, (2016).

Abstract

In this paper we present a new approach for unsupervised classification of materials from the spectra obtained using the Laser-Induced Breakdown Spectroscopy technique. The method is based on the calculation of the correlation matrix between the LIBS spectra, which is interpreted as an Adjacency matrix in the framework of Graph theory. A threshold is applied on the edge values, which is determined through maximization of the Modularity of the Graph. The classification of the spectra is done automatically after the calculation of the Modularity parameter. An example of the application of the proposed method is given, based on the study of six bronze standards of known composition. The advantages of the proposed approach with respect to Principal Component Analysis are also discussed.

Autori: P. Fermo, M. Andreoli, L. Bonizzoni, M. Fantauzzi, G. Giubertoni, N. Ludwig, A. Rossi

Informazioni pubblicazione: Microchemical Journal 129 (2016) 5–15

Abstract

Roman and Byzantine glass shards collected during excavation campaigns around the ancient city of Thugga in northern Tunisia have been characterised by means of various analytical techniques. Portable X-ray Fluorescence (pXRF) was used to determine the glass matrix elemental composition and to identify the elements responsible for the colour. Fibre optic reflectance spectroscopy (FORS) was employed to investigate the chemical nature, the oxidation state and the coordination of the chromophores. X-ray photoelectron spectroscopy (XPS) was here exploited for characterising the outermost layers of the glasses. Elemental analyses by pXRF pointed out that Si, Fe, Al, Ca, K, Rb, Sr, Na and Mg are the main elements present in the glasses. The chromophores responsible for the different shades are Fe for the green shades, Cu and Co for the blue ones, Mn, also used as discolouring agent, for the colourless samples. In relation to the raw materials used for glass production, the comparison with control groups of samples from Northern Tunisia suggests a common provenance of sands.

Autori: E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, F. Poggialini, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta – PArt B Atomic Spectroscopy, 124(1), pp. 40-46, (2016)

Abstract

In this paper, we present a discussion on three different methods recently proposed for the analysis of Laser-Induced Breakdown Spectroscopy (LIBS) spectra, namely the One-Point-Calibration, the Calibration-Free Inverse method, and the Csigma graphs approach. The common characteristics of these methods is the fact of being based on the main equations governing the emission of near-LTE plasmas, i.e. the same theoretical framework that is at the basis of the Calibration-Free LIBS analysis. However, with the purpose to guarantee a higher trueness in the analysis, these methods rely on the information obtained by the analysis of a single reference material, of known composition, for calculating the values of some experimental parameters that would be otherwise difficult to determine. In analogy with a similar approach used in the analysis of X-ray Fluorescence spectra, we place these techniques in the general framework of the so-called Fundamental Parameters Analysis. The three methods were tested and compared on LIBS spectra acquired on modern bronze samples. The advantages and drawbacks of the different approaches are discussed in detail.

Autori: C. Schiavo, L. Menichetti, E. Grifoni, S. Legnaioli, G. Lorenzetti, F. Poggialini, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Journal of Instrumentation, 11(8), (2016)

Abstract

In this paper we present a new instrument specifically realized for high-resolution three-dimensional compositional analysis and mapping of materials. The instrument is based on the coupling of a Double-Pulse Laser-Induced Breakdown Spectroscopy (LIBS) instrument with an optical microscope. The compositional mapping of the samples is obtained by scanning the laser beam across the surface of the sample, while the in depth analysis is performed by sending multiple laser pulses on the same point. Depths of analysis of several tens of microns can be obtained. The instrument presented has definite advantages with respect to Laser Ablation-ICP Mass Spectrometry in many applications related to material analysis, biomedicine and environmental diagnostics. An application to the diagnostics of industrial ceramics is presented, demonstrating the feasibility of Double-Pulse LIBS Imaging and its advantages with respect to conventional single-pulse LIBS imaging.

Autori: L. Bonizzoni, S. Bruni, A. Galli, M. Gargano, V. Guglielmi, N. Ludwig, L. Lodi, M. Martini

Informazioni pubblicazione: Microchemical Journal 126 (2016) 172–180

Abstract

The old library of the Certosa di Pavia still holds thirteen graduals, choir-books with lyrics and scores. Their rich decorations were made by various artist–monks during the fiftieth century. In 2009, the gradual numbered 814 underwent a conservative restoration intervention under the supervision of the Certosa Museum Director, Letizia Lodi, to be on display in Verona, and later it was also included in the exhibition of Arcimboldo works in Milan (2011).

Non-invasive in situ analyses were performed on seven books of this collection, considering fourteen illuminated pages in total, painted by four authors: they showed different technical features, but the same typical materials. Pigments and binders were examined exploiting the synergy between four complementary techniques, namely, EDXRF (energy dispersive X-ray fluorescence), FORS (fibre optics reflectance spectroscopy), FTIR (Fourier transform infrared spectroscopy) and micro-Raman spectroscopy.

Summarizing the palette, the blue pigments used are ultramarine, azurite and, in one case, smalt blue; the red and pink hues are given by red ochre, vermillion and lakes; the yellow ones by orpiment, lead-tin yellow and yellow ochre. The white used is lead white, both in mixtures and as underpainting layer. The application of techniques with different penetration depths allowed to detect the stratigraphic sequences without sampling, opening to the interesting application to off-limits masterpieces. Intriguing is the case of green pigments, recognized as malachite and basic copper sulphates, but possibly also given as a mixture of copper-based and yellow pigments. The different kinds of gold and silver gildings were considered and investigated, accounting for different executing techniques for the different authors. The closing challenge will be determining the binders without any sampling, but exploiting FTIR spectra for the detection of organic binders.

Autori: R. Grassi, E. Grifoni, S. Gufoni, S. Legnaioli, G. Lorenzetti, N. Macro, L. Menichetti, S. Pagnotta, F. Poggialini, C. Schiavo, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta–PArt B Atomic Spectroscopy, 127, pp. 1-6, (2016)

Abstract

In this communication, we present the development of the first double-pulse micro-LIBS (DP-μLIBS) instrument for three-dimensional compositional mapping of materials. The system allows for high-resolution three-dimensional scanning of materials; its advantages with respect to conventional single-pulse micro-LIBS systems are described and discussed. As a test example, we analyzed three Euro coins to show the performances of the system on homogeneous samples (20 Eurocents), heterogeneous samples (1 Euro) and layered samples (5 Eurocents). DP-μLIBS cannot provide isotopic information and has, typically, limits of detection for the elements of interest much higher with respect to Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS). However, when the isotopic information and the extreme sensitivity to trace elements is not be necessary, the results obtained show that DP-μLIBS can be a viable alternative to LA-ICP-MS for the acquisition of high resolution three-dimensional compositional maps.

Autori: E. D’Andrea, S. Pagnotta, E. Grifoni, S. Legnaioli, G. Lorenzetti, V. Palleschi, B. Lazzerini

Informazioni pubblicazione: Applied Physics B: Lasers and Optics, 118(3), pp. 353-360, (2015)

Abstract

A ‘hybrid’ method is proposed for the quantitative analysis of materials by LIBS, combining the precision of the calibration-free LIBS (CF-LIBS) algorithm with the quickness of artificial neural networks. The method allows the precise determination of the samples’ composition even in the presence of relatively large laser fluctuations and matrix effects. To show the strength and robustness of this approach, a number of synthetic LIBS spectra of Cu–Ni binary alloys with different composition were computer-simulated, in correspondence of different plasma temperatures, electron number densities and ablated mass. The CF-LIBS/ANN approach here proposed demonstrated to be capable, after appropriate training, of ‘learning’ the basic physical relations between the experimentally measured line intensities and the plasma parameters. Because of that the composition of the sample can be correctly determined, as in CF-LIBS measurements, but in a much shorter time.

Autori: S. Pagnotta, E. Grifoni, S. Legnaioli, M. Lezzerini, G. Lorenzetti, V. Palleschi

Informazioni pubblicazione: Spectrochimica Acta–PArt B Atomic Spectroscopy, 103-104, pp. 70-75, (2015).

Abstract

In this paper we face the problem of assessing similarities in the composition of different metallic alloys, using the laser-induced breakdown spectroscopy technique. The possibility of determining the degree of similarity through the use of artificial neural networks and self-organizing maps is discussed. As an example, we present a case study involving the comparison of two historical brass samples, very similar in their composition. The results of the paper can be extended to many other situations, not necessarily associated with cultural heritage and archeological studies, where objects with similar composition have to be compared.

Autori: G. Lorenzetti, S. Legnaioli, E. Grifoni, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Atomic Spectroscopy, 112, Art. No. 4946, pp. 1-5, (2015)

Abstract

Laser induced breakdown spectroscopy (LIBS) is a well-established technique for on-line industrial applications where robustness, stability, reliability, speed of analysis and operational availability are important topics to be taken into account. In this work, we propose an advanced methodology for in situ analysis of transition as-cast products during continuous casting with the purpose of improving the productivity and cost-efficiency in the fabrication of stainless steel and special steels. We have applied LIBS combined with Artificial Neural Network (ANN) for elemental analysis of casting steels. We have found that the quantitative determination of the material’s composition across the slab/billet length is possible and that the intermediate chemical composition between sequential heats can be readily identified.

Autori: L. Bonizzoni, A. Galli, M. P. Riccardi, C. Maggioni

Informazioni pubblicazione: X‐Ray Spectrometry 2015, 44, 169-176

Abstract

Speed, manageability and above all non‐destructivity are the main features that make portable X‐ray fluorescence (PXRF) a versatile analytical technique widely used in archaeometry. The extensively use of PXRF instruments in recent years during in situ investigations 1-3 makes the scientific community wonder how to use in the best way the data collected, as close attention must be paid when analysing non‐standard materials such as ancient handcrafted works.

Autori: E. Grifoni, L. Briganti, L. Marras, S. Orsini, M.P. Colombini, S. Legnaioli, M. Lezzerini, G. Lorenzetti, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Heritage Science, 3 (1), Art. No. 26, (2015)

Abstract

“The Plague in Lucca”, a masterpiece of the contemporary painter Lorenzo Viani, was studied by multi-analytical techniques (Multiband, IR and UV fluorescence imaging, micro-Raman spectroscopy, direct exposure–mass spectrometry, gas chromatography–mass spectrometry and energy dispersive X-ray fluorescence) in view of its restoration at the Gallery of Modern and Contemporary Art (GAMC) of Palazzo delle Muse in Viareggio (Lucca, Italy). The analysis allowed to obtain a better understanding of the artistic technique of the painter and to underline critical conservation aspects.

Autori: L. Bonizzoni, C. Canevari, A. Galli, M. Gargano, N. Ludwig, M. Malagodi, T. Rovetta

Informazioni pubblicazione: Heritage Science 2014, 2:15.

Abstract

Several musical instruments in the past centuries were decorated with engravings, inlays, or paintings. This paper focuses on an integrated approach to detect and characterize the kind of dyes when used for the decorations. The multi analytical campaign was performed on a viol made by Joannes Marcus in the second half of the 16^th century. The instrument has been shattered during World War II, and the fragments are now held in Conservatorio Giuseppe Verdi in Milan; they still conserve the original black and white purflings and the painted decorations. The study is of critical importance since Joannes Marcus worked in the sixteenth century and, in this very period, some executive features were introduced in musical instrument making, which are now veritable standards for this kind of instruments.

Autori: G. Bartolozzi, C. Cucci, V. Marchiafava, S. Masi, M. Picollo, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, V. Palleschi, F. Di Girolamo, J. La Nasa, F. Modugno, M.P. Colombini

Informazioni pubblicazione: Heritage Science, 2 (1), Art. no. 29, (2014).

Abstract

This study concerns the application of non-invasive and micro-invasive analyses for the study of a contemporary artwork entitled La Caverna dell’Antimateria (“The Cave of Antimatter”) which was created by Pinot Gallizio in 1958–1959. The work represents one of the most significant examples of industrial painting. It consists of a total of 145 meters of painted canvas, designed in order to cover the entire floor plan of the René Drouin gallery in Paris, where it was displayed for the first time. Gallizio wanted to create an environment in which visitors could find themselves immersed in painting, in what he termed as a “work-environment”.

Non-invasive (Fibre Optic Reflectance Spectroscopy) and micro-invasive analyses (Fourier Transform Infrared and micro-Raman Spectroscopies, Pyrolysis-Gas Chromatography and Gas Chromatography/Mass Spectrometry) were performed on three of the canvases which constitute this work of art in order to obtain information regarding the artistic materials used by Gallizio.

Autori: E. D’Andrea, S. Pagnotta, E. Grifoni, G. Lorenzetti, S. Legnaioli, V. Palleschi, B. Lazzerini

Informazioni pubblicazione: Spectrochimica Acta–PArt B Atomic Spectroscopy, 99, pp. 52-58, (2014)

Abstract

The usual approach to laser-induced breakdown spectroscopy (LIBS) quantitative analysis is based on the use of calibration curves, suitably built using appropriate reference standards. More recently, statistical methods relying on the principles of artificial neural networks (ANN) are increasingly used. However, ANN analysis is often used as a ‘black box’ system and the peculiarities of the LIBS spectra are not exploited fully. An a priori exploration of the raw data contained in the LIBS spectra, carried out by a neural network to learn what are the significant areas of the spectrum to be used for a subsequent neural network delegated to the calibration, is able to throw light upon important information initially unknown, although already contained within the spectrum. This communication will demonstrate that an approach based on neural networks specially taylored for dealing with LIBS spectra would provide a viable, fast and robust method for LIBS quantitative analysis. This would allow the use of a relatively limited number of reference samples for the training of the network, with respect to the current approaches, and provide a fully automatizable approach for the analysis of a large number of samples.

Autori: E. Salerno, A. Tonazzini, E. Grifoni, G. Lorenzetti, S. Legnaioli, M. Lezzerini, L. Marras, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Journal of Applied and Laser Spectroscopy, 1, pp. 22-27, (2014)

Abstract

In this work, a critical review of the current nondestructive probing and image analysis approaches is presented, to revealing otherwise invisible or hardly discernible details in manuscripts and paintings relevant to cultural heritage and archaeology. Multispectral imaging, X-ray fluorescence, Laser-Induced Breakdown Spectroscopy, Raman spectroscopy and Thermography are considered, as techniques for acquiring images and spectral image sets; statistical methods for the analysis of these images are then discussed, including blind separation and false colour techniques. Several case studies are presented, with particular attention dedicated to the approaches that appear most promising for future applications. Some of the techniques described herein are likely to replace, in the near future, classical digital photography in the study of ancient manuscripts and paintings.

Autori: E. Grifoni, S. Legnaioli, M. Lezzerini, G. Lorenzetti, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: Journal of Spectroscopy, 2014, Art. No. 849310, (2014)

Abstract

Laser–induced breakdown spectroscopy (LIBS) data are characterized by a strong dependence on the acquisition time after the onset of the laser plasma. However, time–resolved broadband spectrometers are expensive and often not suitable for being used in portable LIBS instruments. In this paper we will show how the analysis of a series of LIBS spectra, taken at different delays after the laser pulse, allows the recovery of time–resolved spectral information. The comparison of such spectra is presented for the analysis of an aluminium alloy. The plasma parameters (electron temperature and number density) are evaluated, starting from the time–integrated and time–resolved spectra, respectively. The results are compared and discussed.

Autori: M. Scuotto, C. Bassi, M. Lezzerini, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, V. Palleschi

Informazioni pubblicazione: X-Ray Spectrometry, 43 (6), pp. 370-374, (2014)

Abstract

A group of 83 coins, found in the archeological excavations of the ancient Roman city of Tridentum (Trento, Italy), was studied for the determination of their composition, finalized to their classification and cataloging.

The coins, mainly made of copper‐based alloys, were minted between the republican period (II century BC) and the last decades of the western empire (V century AD).

The X‐Ray Fluorescence archaeometric analysis has allowed a revision of the typological classification of the coins through the identification of six broad groups, each one characterized by a peculiar composition of the coins in the group. A tentative assignation of all the unreadable coins to one of the groups identified was proposed, in a way that could suggest also a possible dating of these coins. Copyright © 2014 John Wiley & Sons, Ltd.

Autori: M. Baldassarri G.H. Cavalcanti M. Ferretti A. Gorghinian, E. Grifoni, S. Legnaioli, G. Lorenzetti, S. Pagnotta, L. Marras, E. Violano, M. Lezzerini, V. Palleschi

Informazioni pubblicazione: Journal of Archaeology, vol. 2014, (2014)