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In this article, we compare two analytical methods that have been recently proposed: the columnar density Saha–Boltzmann plot method of Cristoforetti and Tognoni (Cristoforetti, G.; Tognoni, E. Spectrochim. Acta, Part B, 2013, 79–80, 63–71) and the C-sigma model of Aragon and Aguilera (Aragon, C.; Aguilera, J. A. J. Quant. Spectrosc. Radiat. Trans.2014, 149, 90–102). Both methods are based on the exploitation of self-absorbed lines for the characterization of plasmas in laser-induced breakdown spectroscopy experiments. However, although the two methods can be safely applied in many cases, their usefulness is limited in many practical cases of interest because of the intrinsic constraints of the used plasma model or because of the complexity of the numerical treatment. The two methods are presented here and critically discussed. Finally, an extended C-sigma approach is proposed to merge the advantages of the two methods, overcoming their intrinsic limitations and simplifying the numerical treatment.

Max Ernst was one of the most influential artists associated with both the Dada and Surrealist movements. However, until now, only few scientific studies have been devoted to his works. This paper presents the results of a multi-analytical investigation on six oil paintings, made between 1927 and 1942, belonging to the Peggy Guggenheim Collection in Venice (Solomon R. Guggenheim Foundation, New York). Through a combined art historical and scientific approach, this study aims at understanding Ernst’s painting techniques, including frottage, grattage, dripping, and decalcomania, the used materials, and the state of conservation of the artworks. Non-invasive in situ investigations were performed by means of Vis–NIR multi-spectral imaging, X-ray fluorescence, external reflection FTIR and Raman spectroscopy. Imaging analysis revealed important information about Ernst’s painting methods while the other techniques provided useful information about the ground layer, the painting materials and the presence of alteration products. Ernst’s palette discloses great freedom in his use of materials and evolution during the time. This investigation demonstrates that an integrated, non-invasive, diagnostic approach provides a thorough analysis of materials and execution techniques of Ernst’ masterworks allowing an in-depth knowledge of his highly skilled work.

Graphical Abstract:

•Defendente Ferrari was one of the most important painters of the Piedmontese Renaissance.•Interesting traits of his painting technique were discovered.•IR reflectography at 1000-1700 nm highlighted a very rich underdrawing.•The study of the Virgin's blue garment shed light on possible causes of blackening.•GC–MS analyses showed that the artist mastered the use of different binders.

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. Pigments and unconventional materials (such as metal wires, sand) are present in the canvases that form the ceiling. The colours are unevenly distributed on the surface, thus revealing large areas of the white preparation below. In the canvas of the wall, instead, the paint is applied more uniformly and gives a dark colour cast. The analytical results led to the identification of many of the materials used by Gallizio. The pictorial palette consists of both inorganic and organic pigments, while polyvinylacetate, pure or mixed with a siccative oil, was identified as a binder thus confirming what was reported by the artist in his notes. The results of this research provide information concerning the artistic technique used by Pinot Gallizio. The analyses were successfully performed both in situand on micro-samples in order to characterise the pigments of the coloured area, the ground layer and the organic binders.

New approaches in the application of multispectral imaging to the recovery of archeological wall paintings are presented, based on statistical techniques and on a novel method of image treatment (Chromatic Derivative Imaging – ChromaDI) which offers a way of embedding information coming from four spectral bands into a standard RGB image. The methods are applied to some wall paintings from the Tomb of the Monkey, an Etruscan tomb in the necropolis of Poggio Renzo, near the city of Chiusi (Siena), Italy, dated around 480-470 BC. It is shown that the techniques described are able to highlight and enhance a number of details that cannot be perceived in either any of the original channel images or any single processed output channel.

With the aim of reducing the dimensions of a laser-induced breakdown spectroscopy (LIBS) apparatus for building a portable instrument, a diode-pumped Nd:YAG mini-laser at high repetition rate was tested as an excitation source for the quantitative analysis of aluminium alloy samples. Moreover, LIBS spectra acquired by using an ICCD-echelle spectrometer detection system were compared with those obtained by a traditional spectrometer coupled to a non-intensified linear array detector. Calibration curves were built and limits of detections were calculated using both detection systems for magnesium, silicon, copper, titanium, manganese, nickel and iron. The results were compared with those obtained by recently proposed LIBS systems based on the use of microchip lasers.

The influence of crater depth on plasma properties and laser-induced breakdown spectroscopy (LIBS) emission has been evaluated. Laser-induced plasmas were generated at the surface and at the bottom of different craters in a copper sample. Plasmas produced at the sample surface and at the bottom of the craters were spatially and temporally resolved. LIBS emission, temperature, and electronic number density of the plasmas were evaluated. It is shown that the confinement effect produced by the craters enhances the LIBS signal from the laser-induced plasmas.

The concentration of the main minerals present in human hair is measured on several subjects by Calibration-Free Laser-Induced Breakdown Spectroscopy (CF-LIBS) and compared with the results obtained through a commercial analytical laboratory. The possibility of using CF-LIBS for mineral analysis in hair is discussed, as well as its feasibility for the fast and inexpensive determination of the occurrence of heavy-metal poisoning in hair.

•P3HT/PMMA based composites containing 2D-bP layers were prepared for the first time by bP liquid phase exfoliation and polymerization in situ techniques.•The 2D-bP layers were partially exfoliated/intercalated with a good preservation of their physiochemical features.•The 2D-bP layers resulted preferentially allocated in the P3HT polymer phase and its dispersion changes the morphology of the blend P3HT/PMMA.•When a continuous P3HT phase with dispersed 2D-bP nanoflakes was achieved, the charge mobility of P3HT/PMMA polymer matrix was significant despite the presence of 50% wt of a dielectric PMMA.

An extensive analytical study has been performed on a large number of gold coins (Norman-Swabian Augustale and Tarì, Grosso of Lucca, Florin of Florence) minted in Italy from the end of XII century to XIV century. The X-ray fluorescence (XRF) technique was used for verifying the composition of the coins. XRF is a nondestructive technique particularly suited for in situ quantitative analysis of gold and minor elements in the precious alloy. The Florins turned out to have a gold content very close to 24 carats (pure gold) although in a couple of cases we observed relatively high concentrations of iron (around 2%) or lead (around 1%). The Grosso of Lucca has a similar composition, with a measured gold content around 97% due to a higher silver percentage (about 2%), with respect to the average Florin. The Augustali analyzed showed, on average, a gold content around 89%. The average gold content of the Tarì analysed is around 72%, with a relatively large variability. The analysis revealed the use of native gold for the coinage of the Florins, excluding the possibility of recycling gold coming from other sources. On the other hand, the variability observed in the compositions of the Tarì and Augustali could suggest the reuse of Islamic and North African gold. The study could shed some light on the sudden diffusion of gold coins in Italy around the first half of XIII century, allowing hypotheses on the provenience of the gold used for a coinage that dominated the economic trades from then on.