Investigation of the Pigments and Glassy Matrix of Painted Enamelled Qing Dynasty Chinese Porcelains by Noninvasive On-Site Raman Microspectrometry

A selection of 15 Chinese painted enameled porcelains from the 18th century (Qing dynasty) was analyzed on-site by mobile Raman and XRF microspectroscopy. The highly prized artifacts are present in the collections of the Musée du Louvre in Paris and Musée Chinois at Fontainebleau Castle in France. In the painted enamels, pigments such as Naples yellow lead pyrochlore, hematite, manganese oxide and carbon and opacifiers such as lead arsenates were detected. The glassy matrices of the enamels mainly belonged to lead-rich and lead-alkali glass types according to the Raman spectra obtained. The glaze and body phases of the porcelain artifacts were also analyzed. The detection of lead arsenate apatite in some of the blue enamels was significant, indicating the use of arsenic-rich European cobalt ores (smalt) and possibly mixing with Asian cobalt. This characteristic phase has also been identified in French soft-paste porcelains and glass decor and high-quality Limoges enamels from the same period. Based on the shape of the Raman scattering background, the presence of colloidal gold (Au° nanoparticles) was identified in red, orange and pink enamels. Different types of Naples yellow pigments were also detected with Sb-rich, Sn-rich and mixed Sb–Sn–(Zn, Fe?) compositions in the yellow enamels. The results were compared to previous data obtained on Chinese cloisonné and painted enameled metalware and Limoges enamels as well as French enameled watches.

Transformation of S-Bearing Minerals in Organic Matter-Rich Sediments from a Saline Lake with Hydrothermal Inputs

Geothermal systems can provide significant amounts of hydrothermal sulfur to surface waters, increasing salinity and avoiding some of the common anthropic uses. The objective of this study was to investigate the sedimentary neoformation of S-bearing phases in organic matter-rich sediments from a saline lake with hydrothermal inputs (Sochagota Lake, Colombia). Detrital kaolinite and quartz are the main minerals of the materials deposited in the Sochagota Lake. Neoformed clay minerals (illite and illite-dioctahedral vermiculite mixed layers) are concentrated in the central and northern part of the lake in sediments with high organic matter content. The most organic matter-rich materials are characterized by S-bearing minerals: mackinawite, pyrite, and elemental sulfur (S°). FESEM, high-resolution transmission electron microscopy (HRTEM), EDS, and Raman microspectrometry have revealed the presence of cell-shape aggregates of mackinawite nanoparticles filling the inner part of plant fragments, indicating that microorganisms were involved in the hydrothermal sulfur uptake. The alteration of mackinawite in free sulfide excess environment produced the formation of framboidal pyrite. The evolution to conditions with the presence of oxygen favored the formation of complex S° morphologies.

Multi-Modal Compositional Analysis of Layered Paint Chips of Automobiles by the Combined Application of ATR-FTIR Imaging, Raman Microspectrometry, and SEM/EDX

For the forensic analysis of multi-layered paint chips of hit-and-run cars, detailed compositional analysis, including minor/trace chemical components in the multi-layered paint chips, is crucial for the potential credentials of the run-away car as the number of layers, painting process, and used paints are quite specific to the types of cars, color of cars, and their surface protection depending on the car manufacturer and the year of manufacture, and yet overall characteristics of some paints used by car manufacturers might be quite similar. In the present study, attenuated total reflectance-Fourier transform infrared (ATR-FTIR) imaging, Raman microspectrometry (RMS), and scanning electron microscopy/energy-dispersive X-ray spectrometric (SEM/EDX) techniques were performed in combination for the detailed characterization of three car paint chip samples, which provided complementary and comprehensive information on the multi-layered paint chips. That is, optical microscopy, SEM, and ATR-FTIR imaging techniques provided information on the number of layers, physical heterogeneity of the layers, and layer thicknesses; EDX on the elemental chemical profiles and compositions; ATR-FTIR imaging on the molecular species of polymer resins, such as alkyd, alkyd-melamine, acrylic, epoxy, and butadiene resins, and some inorganics; and RMS on the molecular species of inorganic pigments (TiO2, ZnO, Fe3O4), mineral fillers (kaolinite, talc, pyrophyllite), and inorganic fillers (BaSO4, Al2(SO4)3, Zn3(PO4)2, CaCO3). This study demonstrates that the new multi-modal approach has powerful potential to elucidate chemical and physical characteristics of multi-layered car paint chips, which could be useful for determining the potential credentials of run-away cars.

New achievements in the mineral studies by use of the Raman microspectroscopy

By the means of the technique of the Raman microspectrometry, the complex history of the Earth can be better understood. That is why the Raman spectra determinations are the object of interest in the present paper. The examples of such experiments are presented based on the analyses performed in last years in different scientific centers (Potsdam, Banská Bystrica, Budapest). The identification of inclusion content is shown and the conclusions are drawn for fluid inclusions in some quartz samples from two different localities in Poland – in the Carpathians and in the Fore-Sudetic Block. The implications of the Raman analyses are discussed. It results from the Raman analyses performed that not fluorescing, gas-filled bubbles of huge fluid inclusions from the Jabłonki and Rabe vicinity (the tectonic mélange zone in the Carpathians) have the complex composition of CH4, CO2 and N2 in different mutual proportions dependent on the sample and locality. In another place, despite the fluorescing background, only methane has been identified by Raman spectra. Similar gas composition was determined in the inclusions in the vein quartz in the Wądroże Wielkie area (the Fore-Sudetic Block).

Raman microspectroscopy for Cultural Heritage studies

The Raman effect is at the basis of Raman scattering and microspectrometry: in the first part of the chapter, it is very shortly exposed together with differences with infrared (IR) spectroscopy, and advantages and drawbacks of the technique. The importance of the choice of the excitation wavelength, of the spectrometer (fixed, portable and handheld) and of the optics is underlined, while the information provided by the technique for inorganic and organic materials is considered. The surface-enhanced Raman spectroscopy (SERS) theory and principle applications are also taken into account. In the second part of the chapter, all the different applications of Raman and SERS to cultural heritage materials are contemplated: minerals, gemstones, rocks, patinas and corrosion products, glass, pottery, mortars, dyes, binders, resins, paper, parchment, inks and human remains. For each category of objects, the answers that Raman microspectrometry and SERS can give to the archaeometric and conservation-related questions, the in situ investigations, the search of specific spectral parameters and the use of chemometrics are shown, together with the most recent advances in the field.