This book will provide a survey of the major areas in which information derived from vibrational spectroscopy investigations and studies have contributed to the benefit of forensic science, either in ...a complementary or a unique way. This is highlighted by examples taken from real case studies and analyses of forensic relevance, which provide a focus for current and future applications and developments.
Raman spectroscopy of microbial pigments Jehlička, Jan; Edwards, Howell G M; Oren, Aharon
Applied and Environmental Microbiology,
06/2014, Letnik:
80, Številka:
11
Journal Article
Recenzirano
Odprti dostop
Raman spectroscopy is a rapid nondestructive technique providing spectroscopic and structural information on both organic and inorganic molecular compounds. Extensive applications for the method in ...the characterization of pigments have been found. Due to the high sensitivity of Raman spectroscopy for the detection of chlorophylls, carotenoids, scytonemin, and a range of other pigments found in the microbial world, it is an excellent technique to monitor the presence of such pigments, both in pure cultures and in environmental samples. Miniaturized portable handheld instruments are available; these instruments can be used to detect pigments in microbiological samples of different types and origins under field conditions.
The article discusses the applications of Raman spectroscopy in the study of art and archaeology. Raman spectroscopy is becoming significant in art analysis.
Tung oil is favoured in applications such as historic wood consolidation or as varnish component that require a rapid-drying medium compared with linseed oil and other analogues such as walnut oil ...and poppy seed oil. The Raman spectra of tung oil and artificially aged specimens have been obtained and indicate that severe degradation of the C=C unsaturation sites occurs compared with the slower-drying linseed oil. Characteristic spectral signatures of fresh tung oil have been identified which provide diagnostic discrimination between this oil and others used in the preparation and preservation of artworks. Mid-infrared spectra of aged tung oils have served to identify the formation of acidic functionalities which could affect associated pigments and substrates in artwork. Comparative spectra are also reported for a range of other oils such as walnut seed, poppy and sunflower seed oils.
The first porcelains made in Europe during the 17th century and the very beginning of the 18th century, that is, before the discovery of kaolin in Saxony (Germany), are rare and technical analyses ...very limited. In contrast with Meissen Böttger porcelain based on kaolin, these porcelains are made with sand and chymie, like Ottoman fritware. A selection of the blue‐and‐white artefacts belonging to the French national collection is analysed on‐site with mobile portable X‐ray fluorescence (pXRF) and Raman set‐ups: two were assigned to the Poterat Factory at Rouen, three to the Saint‐Cloud Factory and two to the Pavie Factory (Paris). Three types of enamels are identified, lead‐rich (as expected) but also two different lead‐alkaline‐earth alkali enamels, one artefact being covered both with lead‐rich and lead‐poor enamel. The polymerization index deduced from the relative intensity of SiO4 bending and stretching bands indicates different temperatures of firing. Tin is detected in most of the enamels by X‐ray fluorescence (XRF), but cassiterite opacification is only observed for the Pavie Factory artefacts. Arsenic is detected in the blue areas due to the use of European cobalt ores. Comparison of trace and minor elements as well as the type of enamel used suggest that the pot assigned to the Rouen Factory fits much better with a production from the Saint‐Cloud Factory. The two porcelains assigned to the Pavie Factory exhibit similar XRF and Raman signatures that support the attribution based on visual criteria. Combination of the mobile noninvasive XRF and Raman instruments may allow the reliable classification of artefacts on‐site. Raman scattering is very efficient to detect (on‐site) As‐based minor phases.
The first (soft‐paste) porcelains made in Europe during the 17th century and the very beginning of the 18th century, that is, before the discovery of kaolin in Saxony (Germany), are rare and technical analyses very limited. A selection of the artefacts belonging to the French national collection is analysed on‐site with mobile pXRF and Raman set‐ups. Combination of the mobile techniques may allow the reliable classification of artefacts on‐site by considering the type of glaze (lead‐rich or lead‐poor) and the elements associated to cobalt (As, Ni, Cu, Zn, Cd, Ga, Sr).
This review is centered on the linear conjugated polyenes, which encompasses chromatic biomolecules, such as carotenoids, polyunsaturated aldehydes and polyolefinic fatty acids. The linear extension ...of the conjugated double bonds in these molecules is the main feature that determines the spectroscopic properties as light‐absorbing. These classes of compounds are responsible for the yellow, orange, red and purple colors which are observed in their parent flora and fauna in nature. Raman spectroscopy has been used as analytical tool for the characterization of these molecules, mainly due to the strong light scattering produced by the delocalized pi electrons in the carbon chain. In addition, conjugated polyenes are one of the main target molecular species for astrobiology, and we also present a brief discussion of the use of Raman spectroscopy as one of the main analytical tools for the detection of polyenes extra‐terrestrially.
A literature survey is performed to summarize the available databases for the occurrence and identification of carotenoids, conjugated polyenes, and polyolefinic fatty acids from terrestrial and marine sources (obtained from Raman spectroscopic studies). This Review highlights the potential of using this analytical technique for the in situ interrogation of a wide range of organisms without involving chemical treatment or extraction procedures.
Abstract
Raman spectroscopy has been applied to the nondestructive study of ivory artefacts. Molecular Raman spectra of this material have been recorded previously using Fourier‐transform Raman ...spectroscopy (1064‐nm excitation), and attempts were made to differentiate between species of different origin. However, few attempts have been made to examine this interesting material using dispersive Raman spectroscopy, as when using shorter wavelength excitation, the fluorescence background signal tends to overwhelm the Raman signal. In this study, however, a mobile fibre‐optics Raman spectrometer, equipped with 1064‐nm excitation and an InGaAs detector, was used for the direct analysis of ivory artefacts. This approach opens opportunities for the fast and reliable analysis of this material, without the need to move the artefact to the laboratory, helping to act against the illegal trade of this endangered biomaterial.
In Roman wall paintings, blue and green colours are less commonly encountered than red and yellow and were more expensive. Despite this, Pliny and Vitruvius describe the more common compounds used ...for these pigments, translated today as azurite, lazurite, chrysocolla, indigo and Egyptian blue for blues and verdigris, malachite, celadonite, glauconite and chlorite for greens. A confusion in their nomenclature is often found in the most common blue pigment that is the first manufactured compound, Egyptian blue. For greens, celadonite and glauconite were usual and called generically ‘green earths’, but they prove to be difficult to characterize analytically. In this paper, we evaluate the Raman spectroscopic identification of the characteristic Roman blue and green pigments as used in wall paintings using two different laser wavelengths (green and near infrared) and clarify their nomenclature.
Green and blue pigments were scarce and valuable in the Roman wall paintings. Raman spectroscopy is a useful technique for identifying blue and green compounds even in admixture with other minerals. We used two lasers, 780 and 532 nm, which improve the identification probabilities. We discuss the differences between the spectra collected with each laser for each compound and also the right characterization among the greens and blues.
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