Article

Influence of ns-laser wavelength in laser-induced breakdown spectroscopy for discrimination of painting techniques

Authors:
  • Centre de recherche et de restauration des musées de France
  • CY Cergy Paris Universite
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Abstract

The influence of ns-laser wavelength to discriminate ancient painting techniques such as are fresco, casein, animal glue, egg yolk and oil was investigated in this work. This study was carried out with a single shot laser on samples covered by a layer made of a mixture of the cinnabar pigment and different binders. Three wavelengths based on Nd: YAG laser were investigated (1064, 532 and 266 nm). The plasma is controlled at the same electron temperature after an adjustment of pulse energy for these three wavelengths on a fresco sample without organic binder. This approach allows to eliminate the effects of laser pulse energy and the material laser absorption. Afterwards, the emission spectra were compared to separate different techniques. The organic binding media has been separated based on the relative emission intensity of the present CN or C2 rovibrational emissions. In order to test the capability of separating or identifying, the chemometric approach (PCA) was applied to the different matrix. The different solutions in term of wavelength range to optimise the identification was investigated. We focused on the evaluation for the laser wavelength to insure a better separation. The different capacity was interpreted by differentiating the binders by the altered interaction mechanisms between the laser photon and the binders. Also, the electron temperature in the plasma was estimated, which provided the evidences to our findings.

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... Alternatively, LIBS offers an in situ, rapid, and sensitive method, and allows obtaining the information on light elements and in-depth characterization performed without sample preparation [14,15]. These qualities allow LIBS to spread to applications in cultural heritage [16][17][18][19]. LIBS is capable to provide reliable measurement results qualitatively or quantitatively regardless of the element content level (down to some ppm): major, minor or trace components for any kind of material [20]. ...
... Fig. 2 illustrates the thematic studies in the recent years. LIBS is popular for traditional applications, such as the analysis of paintings [19,[30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48][49], metals , ceramics [74][75][76][77][78][79][80][81][82][83][84][85][86][87][88], and stones [15,. The number of annual publications remains almost the same, about 20 on average, but the interest in instrumentation [15,[30][31][32]81,[100][101][102][111][112][113][114][115][116] and biological materials [117][118][119] has become more significant. ...
... One study [19] demonstrated that different laser wavelengths can change the plasma emission by different laser ablation mechanisms according to photon energy: photothermal ablation, photochemical ablation, and photophysical ablation [142]; it plays an important role in plasma temperature. With these characteristic emission profiles, different binding media used in paintings were discriminated (Fig. 8) by all three tested ns lasers: 266 nm, 532 nm, and 1064 nm. ...
Article
Laser-induced breakdown spectroscopy (LIBS) is a versatile elemental analytical technique whose basic elements were described as early as 1962, shortly after the invention of a pulsed laser. Since that time, LIBS has been applied for elemental characterization of various applications. In this work, we review the evolution of LIBS characterization of artworks' materials applications and the development of the LIBS technique for cultural heritage during the years 2015–2020. The LIBS technique has faced and overcome challenges by analytical studies of conservation/restoration and archaeological objects. These challenges required improvements in the LIBS technology in order to obtain good reproducible signals (high S/N, sensitivity) and more reliable quantitative analysis. They also encouraged the LIBS research community to focus on instrumentation development to minimize laser impact, to increase miniaturization (enabling in situ characterization), and to combine different spectroscopic techniques. We aim to encourage more people working on heritage science to use this technique, for whom LIBS may be a brand-new elemental analysis technique, and aim to motivate more LIBS researchers to continue developing the LIBS technique in order to address more issues on conservation, restoration, and archaeology.
... Kaszweska et al. [70] developed a novel approach for UV-LIBS/Optical Coherence Tomography (OCT) integrated in a hybrid mobile instrument for pigment analysis and online monitoring of laser-induced crater depths on a modern painting of unknown dating. Other studies used mock samples, either to improve the depth resolution by characterizing the effect of different laser parameters [71,72], or to develop signal normalization methods for in situ depth profile classification of painted samples using portable LIBS instrumentation [73] (see Section 4). Depth profiles of ancient bones and teeth can provide valuable anthropological information, such as dietary habits and mobility, since these calcified tissues are very stable and can retain their trace element content over long periods of time. ...
... Despite ultrashort LIBS studies in heritage science are still relatively few [75,95], the need to reduce the thermal stress of materials is strongly felt, especially for depth-resolved analyses. To meet this need, the use of UV lasers has been gradually gaining momentum [70][71][72]77,[96][97][98], though the first and second harmonic of Nd:YAG lasers remain the most common LIBS laser sources, both in with benchtop and portable Gold braid, showing different levels of laser treatment. Due to the storage conditions, the left side of the object retained its original color and was used as control (area "a"). ...
Chapter
The potential of Laser-Induced Breakdown Spectroscopy (LIBS) for micro-destructive analysis of cultural heritage objects has been widely demonstrated, and the technique is now ready to be integrated in the permanent instrumentation of conservation laboratories. This chapter presents a review of recent results obtained by LIBS researchers with a focus on three main applications that exemplify the most representative contributions of this technique to cultural heritage science: noninvasive stratigraphic analysis of multilayered samples; feasibility and field studies with portable instrumentation; and underwater LIBS of submerged samples. An overview on the principles of LIBS and employed instrumentation is also provided, together with a discussion on its advantages and drawbacks as compared to well-established techniques for the analysis of cultural heritage.
... These features of LIBS mean that it plays a unique role in the analysis of ancient wall paintings. Even though several works concerning characterization and analysis applications of LIBS in the field of cultural heritage objects have been reported [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], only a very limited number of studies of ancient wall paintings has been completed in recent years and only a few reports have been published on depth profiling studies of ancient wall paintings using the LIBS technique [27,29,37,38]. ...
... These features of LIBS mean that it plays a unique role in the analysis of ancient wall paintings. Even though several works concerning characterization and analysis applications of LIBS in the field of cultural heritage objects have been reported [26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43][44], only a very limited number of studies of ancient wall paintings has been completed in recent years and only a few reports have been published on depth profiling studies of ancient wall paintings using the LIBS technique [27,29,37,38]. ...
... We have compared the results from different laser wavelengths of 266 nm, 532 nm and 1064 nm to discriminate painting techniques with single shot LIBS in our previous work 37 . ...
... Score plot of the two principal components, PC1 and PC2, of total variance between 330 and 465 nm with 266 nm laser excitation37 . ...
... LIBS has been used in a wide variety of analytical applications for the qualitative, semi-quantitative and quantitative analysis of materials and offers specific features of particular relevance in the context of analysis of cultural heritage materials [1,2,[10][11][12]. A recent work has shown the effect of laser excitation wavelength on the analysis by LIBS of painting samples, concluding that short wavelengths favour the characterization of this kind of substrates [21]. ...
... LIB spectra of the model wall paintings were recorded on the paint and mortar side of the substrates by irradiation at 266 nm, a wavelength which has been found optimum for LIBS analysis of this type of samples [21]. All these spectra were obtained with the diffraction grating of 1200 lines mm −1 . ...
Article
Analysis of heritage stone samples, alabaster, gypsum, limestone and marble, and model wall paintings was carried out with a laboratory, hybrid system based on the pulsed laser excitation of Raman, laser-induced fluorescence and laser-induced breakdown spectroscopy signals. The system is based on a nanosecond Q-switched Nd:YAG laser operating at its second (532nm), third (355nm) and fourth (266nm) harmonics and a spectrograph coupled to a time-gated intensified charge coupled device for spectral analysis allowing detection with temporal resolution. For the stone samples, Raman spectra display the characteristic vibration modes of SO4²⁻ of calcium sulfate, in alabaster and gypsum, and of free CO3²⁻ of calcium carbonate, in limestone and marble. Simultaneously acquired laser-induced fluorescence spectra reveal characteristic bands that help to distinguish between heritage stone types. The elemental composition of stone samples is obtained by laser-induced breakdown spectroscopy upon excitation at 355nm. Spectra of all stone samples reveal their elemental composition that includes Ca, Na, Mn and Sr and the presence of molecular species, such as CN, C2 and CaO. Additional emission lines, ascribed to Mg, Si, Al and K, appear with different intensities according to the nature of the stone material. Model wall paintings, based on a red pigment, prepared as fresco or mixed with two different binders, were also studied. The complementary information provided by the three spectroscopic modes allows the identification of the pigment as red vermillion and of the different preparations based on the pigment alone or in mixtures with linseed oil and egg yolk binders.
... Duchene et al. [17] significantly improved the recognition rate of unknown spectra obtained in the laboratory by combining soft independent modeling of class analogy (SIMCA) and partial least-squares discriminant analysis (PLS-DA). In order to promote the separation of different binders used in murals, Bai et al. [18] used LIBS and PCA to prove that 266 nm laser wavelength can obtain better performance. ...
Article
Full-text available
Due to the similar chemical composition and matrix effect, the accurate identification of mineral pigments on wall paintings has brought great challenges. This work implemented an identification study on three mineral pigments with similar chemical compositions by combining LIBS technology with the K-nearest neighbor algorithm (KNN), random forest (RF support vector machine (SVM), back propagation artificial neural network (Bp-ANN) and convolutional neural network (CNN) to find the most suitable identification method for mural research. Using the SelectKBest algorithm, 300 characteristic lines with the largest difference among the three pigments were determined. The identification models of KNN, RF, SVM, Bp-ANN and CNN were established and optimized. The results showed that, except for the KNN model, the identification accuracy of other models for mock-up mural samples was above 99%. However, only the identification accuracy of 2D-CNN models reached above 94% for actual mural samples. Therefore, the 2D-CNN model was determined as the most suitable model for the identification and analysis of mural pigments.
... Nowadays, valuable glass objects benefit from the availability of non-invasive or micro-invasive techniques, which allow distinguishing different glass types within the same glass panel and identifying chromophores, enamels, grisailles, and other decoration layers [20][21][22][23]. Laser spectroscopic techniques, such as laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF), have been combined in several studies to provide complementary elemental and molecular composition in a non-or micro-invasive way [24][25][26][27][28][29][30][31][32]. LIBS is a micro-invasive technique based on the spectral analysis of the luminous plume generated by the pulsed laser ablation of a small amount of material from the surface of the sample and has the capacity for quantitative determination. ...
Article
Full-text available
Flashed glasses are composed of a base glass and a thin colored layer and have been used since medieval times in stained glass windows. Their study can be challenging because of their complex composition and multilayer structure. In the present work, a set of optical and spectroscopic techniques have been used for the characterization of a representative set of flashed glasses commonly used in the manufacture of stained glass windows. The structural and chemical composition of the pieces were investigated by optical microscopy, field emission scanning electron microscopy-energy dispersive X-ray spectrometry (FESEM-EDS), UV-Vis-IR spectroscopy, laser-induced breakdown spectroscopy (LIBS), and laser-induced fluorescence (LIF). Optical microscopy and FESEM-EDS allowed the determination of the thicknesses of the colored layers, while LIBS, EDS, UV-Vis-IR, and LIF spectroscopies served for elemental, molecular, and chromophores characterization of the base glasses and colored layers. Results obtained using the micro-invasive LIBS technique were compared with those retrieved by the cross-sectional technique FESEM-EDS, which requires sample taking, and showed significant consistency and agreement. In addition, LIBS results revealed the presence of additional elements in the composition of flashed glasses that could not be detected by FESEM-EDS. The combination of UV-Vis-IR and LIF results allowed precise chemical identification of chromophores responsible for the flashed glass coloration.
... With the above characteristics, laser spectroscopic techniques including laser-induced breakdown spectroscopy (LIBS) and laser-induced fluorescence (LIF), have been combined in several studies to provide complementary elemental and molecular composition [19][20][21][22][23][24][25]. LIBS is a micro-invasive analytical technique based on the spectral analysis of the luminous plume generated by pulsed laser ablation of a small amount of material from the surface of the sample and has the capacity for qualitative, semi-quantitative and quantitative determinations [23][24][25][26][27]. LIBS has shown to be an effective technique for characterization of glasses from a wide variety of perspectives [25,[28][29][30][31][32][33][34]. ...
Article
The preservation of the integrity of artworks and cultural heritage items during characterization and conservation operations is of high priority, therefore, the application of non-invasive techniques is commonly suggested and recommended. Nonlinear optical microscopies (NLOM), based on the use of tightly focused pulsed femtosecond lasers, are emerging techniques for structural and chemical analysis of heritage objects with micrometric lateral and axial resolution. The results obtained with a set of optical and spectroscopic techniques for the chemical and physical characterization of grisaille paint layers on historical stained glasses, from different chronologies and provenance in Spain, are presented in this work. Optical behaviour and chemical composition were investigated by NLOM, using a laboratory set-up in the modality of Multi-Photon Excitation Fluorescence (MPEF), and by a multi-analytical combination of Field Emission Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry (FESEM-EDS), Laser Induced Breakdown Spectrosocopy (LIBS) and Laser Induced Fluorescence (LIF). Thicknesses values of the historical grisaille paint layers measured with MPEF were compared with those retrieved through FESEM, showing significant consistency and agreement. Under proper conditions, analysis via MPEF microscopy avoids the photochemical and physical damage to the examined materials, thus ensuring their preservation. This approach paves the way for future in-situ, non-invasive stratigraphic investigations on cultural heritage objects.
... Another significant application is the determination of the materials' chemical composition (elemental or molecular). Some spectroscopic techniques are widely used, such as Raman spectroscopy (Kosarova et al. 2013;Syta et al. 2014), laser-induced fluorescence (Wang et al. 2016;Marinelli et al. 2017), laser ablation-inductively coupled plasma mass spectrometry (Mazzocchin et al. 2008;Schmidt et al. 2009;Syta et al. 2014) or laser-induced breakdown spectroscopy (Westlake et al. 2012;Alberghina et al. 2015;Bai et al. 2017). Although many of these methods, e.g. ...
Article
The depth-resolved analysis by means of the laser-induced breakdown spectroscopy (LIBS) is a useful tool in the investigation of multi-layered structures of paintings. The LIBS technique is considered micro-destructive, as it is associated with the formation of the ablation crater. It is important to optimize the laser pulse parameters to minimize the crater size and also to avoid some possible side effects of the laser radiation, such as the material redeposition and the light- or heat-induced pigment discoloration. In the present work, mock-up painting samples were used to investigate the influence of laser radiation characteristics on the ablation process. The first LIBS set-up contains a Nd:YAG laser at the second harmonic frequency (laser wavelength 532 nm, pulse duration ~ 10 ns) and the second set-up is comprised of a modified laser-ablation system equipped with a Nd:YAG laser at the fourth harmonic frequency (laser wavelength 266 nm, pulse duration ~ 5 ns). The influence of different laser wavelengths and different laser energies on the properties of the craters was examined. The effects caused by the laser-ablation process were described.
... The advantage of LIBS is to provide an in situ, rapid, microdestructive approach, performed directly on the sample while simultaneously reducing the analytical procedure [15,16]. LIBS particularly offers an analytical ability for the identification of light elements and distribution of molecular band emission in organic materials such as animal products, polymers, products for heritage conservation like the mural painting (binder, adhesives, and consolidation products), etc. [17][18][19][20]. This work focuses on technical feasibility for preliminary analysis before performing radiocarbon dating for bone samples. ...
Article
In this study, we provide a new application of laser-induced breakdown spectroscopy (LIBS) to evaluate whether ancient bones contain sufficient organic material before radiocarbon dating, which can avoid a complex preliminary analysis of the samples or unnecessary sampling. We examined, as the first step, the plasma induced by a UV (266 nm) ns-laser on pellets of compressed bone powder and, as the second step, the plasma induced on raw bones using different gas environments. First, we carried out a common method for analyzing the organic material using LIBS by observing CN band emission in an ArHe mixture environment; the sample that had not undergone significant diagenesis, containing enough collagen, could be well discriminated for further radiocarbon dating. Then spectral emission from nitrogen and carbon atoms was also recorded for these two types of samples in He and air environments. Calibration curves for carbon and nitrogen concentration of the bone were generated to indicate the residual amount of collagen after undergoing diagenesis (or degradation) and also to illustrate the possible carbonaceous pollution. The results proved that even if only several μg of the material is analyzed for each laser shot, LIBS has the potential to carry out in situ measurements in archaeological context while simultaneously performing a quantitative analysis.
... The advantage of LIBS could be to provide an in situ, rapid, micro-destructive approach, performed directly on the sample while simultaneously reducing the analytical procedure [15,16]. LIBS especially offers an analytical ability for light elements identification and molecular band emission in the organic materials such as animal products, polymers, the products for heritage conservation like the mural painting (binder, adhesives, and consolidation products), etc. [17][18][19][20]. This work focuses on technical feasibility for the preliminary analysis before preforming radiocarbon dating for bone samples. ...
... Generally, these studies demonstrate that LIBS can be successfully used to identify inorganic, but also organic materials such as the protective polymer or binders [73]. Comparing the emission of CN and C 2 bands in the plasma, in fact, Bai et al. [74] discriminated casein, animal glue, oil and egg yolk in mock-up samples painted with a layer of the pigment cinnabar (HgS). To advance the separation, chemometric method based on the Principal Component Analysis (PCA) was used; the 266 nm radiation allowed for a better performance. ...
Article
In this paper, we present a critical review on the applications of the Laser-Induced Breakdown Spectroscopy (LIBS) technique to Cultural Heritage and Archaeology. The strategies used by the groups involved in this kind of research for the analysis of the typical materials of interest (metals, pigments, pottery, glasses, etc.) are discussed in detail, as well as the use of LIBS in combination with other techniques (LIBS and Raman, LIBS and XRF, LIBS and MS). Specific applications of LIBS as a support for Cultural Heritage restoration and the application of the technique for the analysis of underwater objects are treated in separated sessions. In conclusion, new trends of LIBS for Cultural Heritage and Archaeology (micro-LIBS analysis, 3D elemental imaging, Surface- and Nanoparticle-Enhanced LIBS) are introduced and discussed.
Article
Full-text available
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Laser-induced breakdown spectroscopy (LIBS) was used in combination with Raman microscopy, for the identification of pigments in different types of painted works of art. More specifically, a 19th century post-Byzantine icon from Greece and two miniature paintings from France were examined and detailed spectral data are presented which lead to the identification of the pigments used. LIBS measurements yielded information on the presence of pigments or mixtures of pigments based on the characteristic emission from specific elements. Identification of most pigments was performed by Raman microscopy. As demonstrated in this work, the combined use of LIBS and Raman microscopy, two complementary techniques, leads to a detailed characterization of the paintings examined with respect to the pigments used.
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With the objective of detection and identification of explosives, different organic compounds, including aromatic nitrocompounds, RDX, anthracene, 2,4-diaminotoluene (DAT), 4-methyl-3-nitroaniline (MNA) and pentaerythritol (PENT) have been analyzed by laser induced breakdown spectroscopy (LIBS). To avoid the secondary ionization and to discriminate between the spectral contribution due to air from that of the compound in the plasma generated in air, the emission signatures from atomic lines (C at 247.9nm, H at 656.3nm, N at 746.8nm and O at 777.2nm) and molecular bands (CN at 388.3nm and C2 at 516.5nm) have been investigated in plasmas generated in air and in helium. The different possible pathways leading to the observation of molecular emissions have been studied, together with a discussion of the most useful tools for the explosives discrimination. Moreover, the effect of the laser fluence on the atomic and molecular emissions and their relationship with the oxygen balance of an organic explosive is presented.
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Laser-induced breakdown spectroscopy (LIBS) and Raman microscopy were used for the identification of pigments in wall painting. Raman spectroscopy, which provides the molecular ‘fingerprint’ of the compound, is nowadays widely used by the archaeometry community, especially for pigment analysis. LIBS, which provides the elementary composition of samples, is a rapid noncontact method, enabling layer-by-layer analysis through a precise laser ablation of the sample. This work deals with the behavior of pigments after a LIBS analysis, by trying to identify the compounds before and after the laser shot. Six commercial pigments prepared with the fresco technique were investigated: ultramarine blue, red lead, charcoal, a yellow and a red ochre, and a green earth. Raman spectra, acquired on the sample surface and in the crater induced by LIBS analysis, were compared. The results show that these pigments are well recognized after a LIBS measurement. The analysis of green earth illustrates that the combination of these two techniques gives complete information from a sample. Copyright © 2007 John Wiley & Sons, Ltd.
Article
Inductively coupled plasma-mass spectrometry (ICP-MS) is a relatively new analytical technique, growing in popularity, that offers many advantages over previously available instrumentation for the measurement of both the elemental and isotopic composition of metallic antiquities. The application of this method of analysis to archaeological metalwork is discussed and the technique compared with other methods of analysis commonly used in archaeometallurgy. Particular attention is drawn to the potential pitfalls and difficulties associated with ICP-MS and the need for extremely careful sample preparation and instrument operation.
Article
In this work we evaluate the performance of a commercial Échelle spectrometer coupled with an intensified charge-coupled device (ICCD) detector for the analysis of solid samples by laser-induced plasma spectroscopy (LIPS) in air at atmospheric pressure. We compare results obtained in aluminum alloy samples with this system and with a ‘conventional’ Czerny-Turner spectrometer coupled to an intensified photodiode array (IPDA). We used both systems to generate calibration curves and to determine the detection limit of minor elements, such as Mg, Cu, Si, etc. Our results indicate that no significant differences in terms of analytical figures of merit exist between the Échelle/ICCD system and a conventional Czerny-Turner spectrometer with IPDA. Moreover, measurements of plasma temperature and electron density using the two assemblies give, in general, very similar results. In the second part of this work, we aim to present a critical view of the Échelle spectrometer for LIPS applications, by drawing up the balance sheet of the advantages and limitations of the apparatus. The limitations are either inherent to the dispersion method, or result from the dynamic range of the detector. Moreover, the minimum ICCD readout time does not allow a fast data acquisition rate. On the other hand, the Échelle spectrometer allows complete elemental analysis in a single shot, as spectral lines of major, minor and trace constituents, as well as plasma parameters, are measured simultaneously. This enables a real-time identification of unknown matrices and an improvement in the analytical precision by selecting several lines for the same element.
Article
This study aims at differentiating several organic materials, particularly polymers, by laser induced breakdown spectroscopy. The goal is to apply this technique to the fields of polymer recycling and cultural heritage conservation. We worked with some usual polymers families: polyethylene (PE), polypropylene (PP), polyoxymethylene, (POM), poly(vinyl chloride), polytetrafluoroethylene, polyoxyethylene (POE), and polyamide for the aliphatic ones, and poly(butylene terephthalate), acrylonitrile–butadiene–styrene, polystyrene, and polycarbonate for the aromatic ones. The fourth harmonic of a Nd:YAG laser (266 nm) in ambient air at atmospheric pressure was used. A careful analysis of the C2 Swan system (0,0) band in polymers containing no C–C (POM), few C–C (POE), or aromatic C–C linkages led us to the conclusion that the C2 signal might be native, i.e., the result of direct ablation from the sample. With use of these results, aliphatic and aromatic polymers could be differentiated. Further data treatments, such as properly chosen line ratios, principal component analysis, and partial least squares regression, were evaluated. It was shown that many polymers could be separated, including PE and PP, despite their similar chemical structures. Figure LIBS analysis for cultural heritage conservation
Article
We have investigated the spectra and decay characteristics of the fluorescence produced in oil colours under pulsed laser excitation. It was found possible to identify prigments in paintings by measuring the fluorescence, and it is suggested that the laser-induced fluorescence method can be used to detect forgeries in oil paintings.
Article
Time-integrated and time-resolved fluorescence spectra were measured at 300 K in resins under N_2 laser excitation. Fluorescence spectra of mastic and dammar are similar to those of varnishes which contain these resins. Fluorescence from lac dye is observed in shellac.
Article
Laser ablation-inductively coupled plasma mass spectrometry (LA-ICPMS) is a solid sampling technique in continuous expansion in all types of research fields in which direct multi-elemental or isotopic analysis is required. In particular, this technique shows unique characteristics that made its use recommended in many archaeometric applications, where valuable solid artifacts are often the target samples, because it offers flexibility to achieve spatially resolved information with high detection power and a wide linear range, in a fast and straightforward way, and with minimal sample damage. The current review provides a systematic survey of publications that reported the use of LA-ICPMS in an archaeological context, highlights its main capabilities and limitations and discusses the most relevant parameters that influence the performance of this technique for this type of application.
Article
The characterization of the binding media and pigments in modern and contemporary paintings is important for designing safe conservation treatments, as well as for determining suitable environmental conditions for display, storage and transport. Raman spectroscopy is a suitable technique for the in situ non-destructive identification of synthetic organic pigments in the presence of the complex binding media characteristic of synthetic resin paints or colour lithographic inks. The precise identification of a pigment by comparing its spectrum to that of a reference is necessary when conservation treatments with aqueous solutions or organic solvents are being considered for a work of art, since solubility properties can sometimes vary within the same pigment group. The Raman spectra of 21 yellow synthetic organic pigments, belonging to the monoazo, monoazo lakes, diarylide, disazo condensation, benzimidazolone, bisacetoacetarylide, azo-methine metal complex, isoindolinone and isoindoline groups are presented. Since modern artists frequently mixed paint developed for other applications, in addition to colorants developed as artists' paints, other synthetic organic pigments were included in the spectral database. Two monoazo pigments, Pigment Yellow 1 and Pigment Yellow 3, a benzimidazolone, Pigment Yellow 154 and a phthalocynanine, Pigment Green 7, were identified in sample cross-sections from four modern and contemporary paintings in the collection of The Museum of Modern Art in Ljubljana, Slovenia.
Etude et développement de la spectroscopie d'emission optique sur plasma induit par laser pour l'analyse de terrain: un exemple d'application aux oeuvres d'art
  • R Bruder
R. Bruder, Etude et développement de la spectroscopie d'emission optique sur plasma induit par laser pour l'analyse de terrain: un exemple d'application aux oeuvres d'art. PhD thesis, Université Pierre et Marie Curie Paris VI, 2008.
Etude et optimisation de la méthode LIBS (Laser induced breakdown spectroscopy) pour l identification de matériaux organiques appliquée au recyclage des plastiques et à la conservation du patrimoine
  • Gregoire
Gregoire, Etude et optimisation de la méthode LIBS (Laser induced breakdown spectroscopy) pour l identification de matériaux organiques appliquée au recyclage des plastiques et à la conservation du patrimoine, PhD thesis, Université de Strasbourg, 2013.
  • D Anglos
  • V Detalle
D. Anglos, V. Detalle, Cultural Heritage Applications of LIBS, Laser-Induced Breakdown Spectroscopy, Volume 182 of the series Springer Series in Optical Sciences (2014) 531-554.
Laser-induced Breakdown Spectroscopy (LIBS) for the Characterization of Organic Materials in Mural Paintings
  • S Grégoire
  • M Boudinet
  • F Pelascini
  • F Surma
  • Y Holl
  • V Motto-Ros
  • S Duchêne
  • V Detalle
S. Grégoire, M. Boudinet, F. Pelascini, F. Surma, Y. Holl, V. Motto-Ros, S. Duchêne, V. Detalle, Laser-induced Breakdown Spectroscopy (LIBS) for the Characterization of Organic Materials in Mural Paintings, in Lasers in the Conservation of Artworks IX, Archetype Publications Ltd, U.K., 2013