Search

Abstract Cinnabar (α-HgS) is a common mineral used in various fields. The identification of cinnabar can be achieved by classic mineralogical methods and instrumental methods. X-ray diffraction (XRD) is the most reliable instrumental method for identifying material phases, but the sampling process and the immovable instrument limit its wider application in the cultural heritage field. The occurrence of Assing S. p. A. Surface Monitor, a portable system integrating X-ray fluorescence (XRF) and XRD, provides researchers with a new solution. Raw mineral, polished gemstone, pigment powder and Chinese ink stick claimed to be composed of cinnabar were measured by the system as well as laboratory-type XRD and micro-Raman techniques in this study. The qualitative XRF results were applied to determining the elements existing in the samples and thus defining the range of possible phases. Patterns obtained were compared carefully with the characteristic lines to determine the most likely phases, while the pattern appearances were compared in order to recognize the different states of cinnabar and generalize the experience for identifying cinnabar by the system. The Raman spectra obtained were compared and analyzed in order to learn the best parameters and determine the real composition of each sample. The results indicate that the XRF detector is sensitive enough to distinguish cinnabar from another red pigment, minium (Pb3O4), without destructive preparation provided that the desired phases occupy a major content in the sample, while the laser micro-Raman is even better in application range and measurement speed but correct analysis of the spectra is highly dependent on experience and literatures. The portable coupled XRF-XRD system and the micro-Raman provide researchers with convenient and efficient options to preliminarily identify minerals like cinnabar, which is significantly meaningful to several research fields including mineralogy, heritage science, material science, etc. Article highlights Two efficient and non-destructive methods for the preliminary identification of minerals like cinnabar were developed. The optimum instrument parameters for the effective measurement of different cinnabar samples were given in detail. The study provides useful data for various fields including analytical science, material science, heritage science, etc.

We investigated the heat dissipation in heterostructure field-effect transistors (HFETs) using microRaman measurement of the temperature in active AIGaN/GaN. By varying the gate structure, the heat dissipation through the gate was clearly revealed. The temperature increased to 120 °C at the flat gate device although the inserted gate increased to only 37 °C. Our results showed that the inserted gate structure reduced the self-heating effect by three times compared to the flat gate structure. Temperature mapping using micro-Raman measurement confirmed that the temperature of the near gate area was lower than that of the near drain area. This indicated that the inserted gate electrode structure effectively prohibited self-heating effects.

Raman spectroscopy is gaining ground in the analysis of microplastics, especially due to its high spatial resolution that allows the investigation of small plastic particles, whose numeric abundance is argued to be particularly relevant in aquatic systems. Here, we aimed at outlining the status of Raman analysis of microplastics from aquatic systems, highlighting the advantages and the drawbacks of this technique and critically presenting tools and ways to effectively employ this instrument and to improve the spectra obtained and their interpretation. In particular, we summarized procedural information for the use of Raman spectroscopy, and we discussed issues linked to fluorescence interference and the analysis of weathered polymers, which may complicate the interpretation of Raman signatures. In this context, a deep understanding of the different plastic polymers and their Raman peaks and chemical fingerprints is fundamental to avoid misidentification. Therefore, we provided a catalog with detailed information about peaks of most common plastic polymers, and this represents, to the best of our knowledge, the first comprehensive resource that systematically synthesized plastic Raman peaks. Additionally, we focused on plastic additives, which are contained in the majority of plastics. These compounds are often intense in Raman scattering and may partly or completely overlie the actual material types, resulting in the identification of additives alone or misidentification issue. For these reasons, we also presented a new R package “RamanMP” that includes a database of 356 spectra (325 of which are additives). This will help to foster the use of this technique, which is becoming especially relevant in microplastic analysis.

Microplastics are a widespread contaminant found not only in various natural habitats but also in drinking waters. With spectroscopic methods, the polymer type, number, size, and size distribution as well as the shape of microplastic particles in waters can be determined, which is of great relevance to toxicological studies. Methods used in studies so far show a huge diversity regarding experimental setups and often a lack of certain quality assurance aspects. To overcome these problems, this critical review and consensus paper of 12 European analytical laboratories and institutions, dealing with microplastic particle identification and quantification with spectroscopic methods, gives guidance toward harmonized microplastic particle analysis in clean waters. The aims of this paper are to (i) improve the reliability of microplastic analysis, (ii) facilitate and improve the planning of sample preparation and microplastic detection, and (iii) provide a better understanding regarding the evaluation of already existing studies. With these aims, we hope to make an important step toward harmonization of microplastic particle analysis in clean water samples and, thus, allow the comparability of results obtained in different studies by using similar or harmonized methods. Clean water samples, for the purpose of this paper, are considered to comprise all water samples with low matrix content, in particular drinking, tap, and bottled water, but also other water types such as clean freshwater., B. E. Oßmann thanks the Bavarian State Ministry of the Environment and Consumer Protection for funding the projects “Detection of microplastics in selected foods” and “Expansion of the analytics of microplastics in food.” S. Lacorte acknowledges funding from the Ministry of Science and Innovation of Spain (project PID2019-105732GB-C21). J. Weisser, K. Glas, T. Hofmann, N. P. Ivleva, and E. von der Esch receive funding from the Bavarian Research Foundation (Bayerische Forschungsstiftung (BFS), AZ-1258-16 (“MiPAq”). N. P. Ivleva thanks the Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung (BMBF), projects 02WPL1443A “SubμTrack” and 03F0851B “HOTMIC”) for financial support. D. Fischer and F. Fischer acknowledge funding from the projects MicroCatch_Balt, PLASTRAT, PLAWES by the BMBF in the call “Plastics in the environment,” as well as from the BONUS BLUE BALTIC project MICROPOLL, which has received funding from BONUS (Art 185), funded jointly by the EU and the BMBF. N. Zumbülte and C. S. Witzig acknowledge funding by the BMBF of the project “MicBin.”

Background: Topological insulator (TI), Bi2Te3 is a new class of quantum materials. Having ultralow dissipation surface states, TIs hold great promise toward different potential applications. Micro-Raman spectroscopy is a conventional and non-destructive technique, which has been widely used to characterize the structural and electronic properties of thermoelectric materials. Objective: The objective of this study is to review power dependent and temperature dependent Raman spectra of B2Te3 nanoflakes on SiO2/Si substrate to estimate the temperature coefficient and thermal conductivity of these flakes for possible application of this material in thermoelectrics. Methods: Bi2Te3 flakes of different thicknesses were mechanically exfoliated from high-quality bulk Bi2Te3 crystal using scotch tape on 300 nm SiO2/ Si substrates. The power dependent and temperature dependent Raman spectra were acquired with the help of HORIBA LabRAM confocal micro- Raman system in a backscattering geometry. Result: The observed power dependent and temperature dependent Raman spectra of Bi2Te3 nanoflakes follow the same trend as discussed in various pieces of literature. From temperature coefficient and power coefficient values, the in-plane thermal conductivity has been estimated, which is found to be in the order of 102 W/m-K. The enhancement in the thermal conductivity suggests that the underlying substrate significantly affects the heat dissipation of the Bi2Te3 flake based on the coupling strength with Bi2Te3. Conclusion: This work provides a good platform to understand the role of the substrate on the thermal conductivity of exfoliated Bi2Te3 nanoflakes and this study can be extended to other substrates.

SEM–EDX and Raman spectroscopy analysis of radioactive compounds is often restricted to dedicated instrumentation, within radiological working areas, to manage the hazard and risk of contamination. Here, we demonstrate application of WetSEM® capsules for containment of technetium powder materials, enabling routine multimodal characterisation with general user instrumentation, outside of a controlled radiological working area. The electron transparent membrane of WetSEM® capsules enables SEM imaging of submicron non-conducting technetium powders and acquisition of Tc Lα X-ray emission, using a low cost desktop SEM–EDX system, as well as acquisition of good quality μ-Raman spectra using a 532 nm laser.

This pilot study presents a practical approach to detecting and visualising the initial forms of caries that are not clinically registered. The use of a laser-induced contrast visualisation (LICV) technique was shown to provide detection of the originating caries based on the separation of emissions from sound tissue, areas with destroyed tissue and regions of bacterial invasion. Adding microRaman spectroscopy to the measuring system enables reliable detection of the transformation of the organic–mineral component in the dental tissue and the spread of bacterial microflora in the affected region. Further laboratory and clinical studies of the comprehensive use of LICV and microRaman spectroscopy enable data extension on the application of this approach for accurate determination of the boundaries in the changed dental tissue as a result of initial caries. The obtained data has the potential to develop an effective preventive medical diagnostic approach and as a result, further personalised medical treatment can be specified. © 2022 by the authors. Licensee MDPI, Basel, Switzerland. Russian Science Foundation, RSF: 21-15-00026; Ministry of Science and Higher Education of the Russian Federation: N 075-15-2021-1351 Funding: This work was funded by a grant from the Russian Science Foundation, grant number 21-15-00026. The access to scientific equipment and methodology was provided under support from the Ministry of Science and Higher Education of Russia, agreement N 075-15-2021-1351.

In this study, we aim at establishing a method to evaluate the spatial distribution and content of gefitinib in tablets without destroying the tablets. The content of gefitinib tablets was determined by HPLC. Using confocal micro-Raman spectroscopy, with a wavelength of 785 nm and power of 10%, gefitinib, starch, and hydrated magnesium silicate were scanned. Tablets with five concentrations of gefitinib (15.63–31.25%) were scanned with a 1000 × 1000 μm spectral resolution and live video imaging was performed. The surfaces of gefitinib tablets were scanned and images were obtained by a continuous scanning method. Characteristic Raman spectra of tablets were obtained after surface scanning and map reviews of tablets with five concentrations of gefitinib for rapid and accurate identification. The characteristic spectral bands of gefitinib, starch, and hydrated magnesium silicate were 1620 cm–1, 480 cm–1, 1350 cm–1 respectively. Comparing the surfaces of the tablets, it was found that the tablets with a flat and round surface are more suitable for Raman spectroscopy. Live video imaging and scanning maps of five concentrations of gefitinib were performed. The results showed that the product with the content of 16.12% had a good mixing homogeneity. In conclusion, confocal micro-Raman spectroscopy can detect the spatial distribution and content of gefitinib tablets without destroying tablets.

The study of manufacture technologies and provenance of raw materials in archaeological potteries are two fundamental aspects in providing information about sociocultural aspects on past societies. The most acknowledged technique in this field is represented by minero‐petrographic analysis, allowing to describe the compositional features of the artefacts and to link them to geological outcrops and technologic processes. In the case of fine‐grained potteries, minero‐petrographic analysis might sometime give back not clear results, requiring the use of high‐resolved methods. In this framework, information about raw materials and firing techniques might be provided by the support of micro‐Raman spectroscopy, able to supply information on mineral grains not detectable under a microscope and for which powders diffraction methods are not able to provide unique interpretations. In this work, particular attention was devoted to the phases formed during the ceramic body annealing, especially to newly formed feldspars, exhibiting a not natural occurring composition. Their correct identification, important for thermometric studies, is possible only with the use different techniques, due to the different investigated aspects (structure, composition and lattice dynamics). Fine‐grained potteries from the famous site of Volterra, Tuscany (Italy) have been characterized as case study during a comparative evaluation of the results obtained by different techniques (micro‐Raman analysis, optical microscopy [OM], X‐ray diffraction [XRD] and scanning electron microscope energy dispersive spectrometry [SEM‐EDS]) on the same mineral grains. The obtained results demonstrated how micro‐Raman spectroscopy might improve interpretation of data collected with different methods in several aspects, from provenance to firing temperature estimation.

Titanium chromium nitride (TiCrN) films were prepared under various nitrogen flow rates (7–18 sccm) via co-sputtering. It was argued that the target poisoning effect governs the deposition process ...

We developed an experimental metrology for measuring local strain in molecular beam epitaxially (MBE) grown crystalline chalcogenide thin films through micro-Raman spectroscopy. For In2Se3 and Bi2Se3 on c-plane sapphire substrates, the transverse-optical vibrational mode (A1 phonon) is most sensitive to strain. We first calibrated the phonon frequency–strain relationship in each material by introducing strain in flexible substrates. The Raman shift–strain coefficient is −1.97 cm–1/% for the In2Se3 A1(LO + TO) mode and −1.68 cm–1/% for the Bi2Se3 A1g2 mode. In2Se3 and Bi2Se3 samples exhibit compressive strain and tensile strain, respectively. The observations are compliant with predictions from the opposite relative thermal expansion coefficient between the sample and the substrate. We also map strain cartography near the edge of as-grown MBE samples. In In2Se3, the strain accumulates with increasing film thickness, while a low strain is observed in thicker Bi2Se3 films.

Advancements in the field of nanotechnology have resulted in the emergence of a large variety of engineered nanomaterials for innumerable applications. Despite the ubiquitous use of nanomaterials in daily life, concerns regarding the potential toxicity and safety of these materials have also been raised. There is a high demand for assessing the unwanted effects of both gold and silver nanoparticles, which is increasingly being used in biomedical applications. This paper deals with the study of stress due to silver and gold nanoparticles of varying size on red blood cells (RBCs) using Raman tweezers spectroscopy. RBCs were incubated with nanoparticles of size in the 10–100 nm range with the same concentrations, and micro-Raman spectra were recorded by optically trapping the nanoparticle-treated live RBCs. Spectral modifications implicating hemoglobin deoxygenation were observed in all nanoparticle-treated RBCs. One of the probable reason for the deoxygenation trend can be the adhesion of nanoparticles onto the cell surface causing imbalance in cell functioning. Moreover, the higher spectral variations observed for silver nanoparticles indicate that oxidative stress is involved in cell damage. These mechanisms lead to the modification in the hemoglobin structure because of changes in the pH of cytoplasm, which can be detected using Raman spectroscopy.

Medieval glazed ceramics, dated to the early 15th century, excavated at the Belgrade Fortress, Serbia, were investigated by combining optical microscopy, X-ray powder diffraction (XRPD), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), micro-Raman spectroscopy and multivariate statistical analysis. The decoration and style of the investigated ceramics were characteristic of workshops from different areas of the medieval Serbian State: Ras, Krusevac and Belgrade/Smederevo. Comparison was made with ceramic samples from the same period excavated at the Studenica Monastery, the hitherto earliest workshop discovered, which were used as reference material for the Ras area. Ceramics from the Belgrade Fortress were covered with a transparent, lead-based glaze. The majority of the glazes were produced by application of mixture of lead oxide and quartz to the clay body, whereas only two samples were glazed by application of lead oxide by itself. The brown colours of the glaze originated from Fe-based spinel, whereas copper and iron were responsible for the colouring of the green and yellow glazes. The obtained results revealed glazing technology taken from Byzantine tradition.

Conservation of the preserving medium is an essential element for the proper preservation of specimens in fluid collections. However, the preservatives can become chemically altered over time or be lost by processes such as evaporation. To combat such changes and properly care for and maintain immersed specimens, it is therefore necessary to know what preservative fluid was initially chosen and how its chemistry may have evolved with time. The present work explores the possibilities offered by Raman spectrometry for a rapid, nondestructive, noninvasive alternative to commonly employed chemical identification tests, which are often limited to the identification of simple fluids. In a first step, fluids were reconstituted and analyzed in small standard glass containers to evaluate the potential of the technique. Then we successfully applied the procedure to real cases and considered its possible use to estimate the concentration of ethanol and to detect small quantities of formaldehyde (down to 1%). The results demonstrate the power of this technique, which opens up new possibilities for the management of fluid collections.

Zeolites are present in numerous outcrops of volcanites of different ages in Sicily (Italy). Some of these outcrops are important because they constitute the ideal genesis conditions of some of these minerals, which represent geological indicators of chemical and geothermal gradients involved during their formation. For this purpose, a group of zeolites coming from areas of the Ionian coast and Palagonia village (Eastern Sicily) was investigated by means of Raman spectroscopy. In the geological record, these areas have been influenced by intense volcanic events that produced mineralization of hydrothermal origin. Sicilian zeolite samples were analysed in situ using different mobile Raman apparatus, directly on the outcrops of Aci Castello and the nearby Lachea Island, or in local collections where they are preserved. Some of these samples have been then analysed using laboratory micro-Raman to compare the results and identify the zeolite types. The strength and weakness points of each instrument have been highlighted. Often, the Raman spectra of zeolites are affected by broad fluorescence, making them of difficult interpretation. However, satisfying results were obtained with portable devices, whose identifications were confirmed by micro-Raman, discerning zeolites of different groups, such as analcime, chabazite, natrolite and phillipsite. The use of portable instruments has demonstrated the possibility to obtain identification of zeolites and related minerals both on site and in the laboratory, whose results match with the geological setting of the considered areas.

Optical techniques are becoming increasingly popular for the analysis of body fluids, particularly so after the onset of the COVID-19 pandemic. Raman spectroscopy has found special significance among them due to its ability to perform label-free investigations of biological solutions with high sensitivity and specificity. The integration of Raman spectroscopy with optical tweezers—Raman Tweezers—has been explored in conducting biochemical investigations on individual red blood cells. We present in this chapter an evaluation of various stress agents, such as intravenous fluids, certain chemicals, and metal nanoparticles, on live, human red blood cells using the Raman Tweezers technique. The technique found efficacy in monitoring hemoglobin deoxygenation, heme aggregation, heme degradation, and membrane damage in red blood cells under the influence of exogenous agents.

Micro-Raman spectroscopy has been preferred recently to measure the thermal conductivity of thin-films due to its nondestructive and non-contact nature. However, the thermal size effects originating from both localized heat generation from Raman laser and phonon scattering at boundaries may cause erroneous estimation of the thermal conductivities with the current approach. In this study, the gray phonon Boltzmann transport equation (BTE) is solved to improve the results of micro-Raman thermal conductivity measurements. Due to the frequency independence of single phonon mode in the gray BTE model, our method stays ahead of most theoretical methods in calculation time while giving adequate agreement with the literature data. The improved thermal conductivities are evaluated at various laser powers and focal lengths. Subsequently, the values of thermal conductivities are compared with a simple slab model in which the deduction of thermal conductivity in sub-micron thicknesses is calculated using reduced heat flux through the slab resulting from phonon directional energy densities. The results show that subsequent errors are present in measuring the thermal conductivity of relatively thick, thin films with this technique which are noticed by comparing with the simple slab model. Finally, a virtual micro-Raman thermography experiment is developed, and its validity is verified by the same slab model.

The deposition of amyloid plaques is considered one of the main microscopic features of Alzheimer's disease (AD). Since plaque formation can precede extensive neurodegeneration and it is the main clinical manifestation of AD, it constitutes a relevant target for new treatment and diagnostic approaches. Micro-Raman spectroscopy, a label-free technique, is an accurate method for amyloid plaque identification and characterization. Here, we present a high spatial resolution micro-Raman hyperspectral study in transgenic APPswePS1ΔE9 mouse brains, showing details of AD tissue biochemical and histological changes without staining. First we used stimulated micro-Raman scattering to identify the lipid-rich halo surrounding the amyloid plaque, and then proceeded with spontaneous (conventional) micro-Raman spectral mapping, which shows a cholesterol and sphingomyelin lipid-rich halo structure around dense-core amyloid plaques. The detailed images of this lipid halo relate morphologically well with dystrophic neurites surrounding plaques. Principal Component Analysis (PCA) of the micro-Raman hyperspectral data indicates the feasibility of the optical biomarkers of AD progression with the potential for discriminating transgenic groups of young adult mice (6-month-old) from older ones (12-month-old). Frequency-specific PCA suggests that plaque-related neurodegeneration is the predominant change captured by Raman spectroscopy, and the main differences are highlighted by vibrational modes associated with cholesterol located majorly in the lipid halo.

Marine plastic debris is a widely recognized environmental issue. By employing an optical micro-Raman tweezers setup, we have identified the composition of particles trapped in marine aggregates collected from the coastal surface waters around the subtropical island of Okinawa, Japan. This chemical identification of small microplas- tics at the single-particle level contributes to extending our knowledge of plastic pollution in the ocean around a Blue Zone region.

Historically, sutras played an important role in spreading Buddhist faith and doctrine, and today these remain important records of Buddhist thought and culture. A Mahamayuri Vidyarajni Sutra with polychrome paintings was found inside the cavity on top of the Nanmen Buddhist pagoda, built in the early Tang dynasty (618–627 CE) and located in Anhui Province, China. Textile was found on the preface which is strongly degraded and fragile. Unfortunately, the whole sutra is under severe degradation and is incomplete. Technical analysis based on scientific methods will benefits the conservation of the sutra. Optical microscopy (OM), micro-Raman spectroscopy combined with optical microscope (Raman), scanning electron microscopy in combination with energy dispersive X-ray analysis (SEM–EDS) and Fourier Transform Infrared Spectroscopy (FTIR) were used to characterize the pigment and gilded material, as well as the paper fiber and textile. Pigments such as cinnabar, minium, paratacamite, azurite, lead white were found. Gilded material was identified as gold. A five-heddle warp satin, made of silk, was found as the textile on the preface of the sutra. The sutra’s preface and inner pages were made of paper comprised of bamboo and bark. As a magnificent yet recondite treasure of Buddhism, the sutra was analyzed for a better understanding of the material. A conservation project of the sutra will be scheduled accordingly.

Fil: Zandalazini, Carlos Ivan. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Cordoba. Instituto de Investigaciones en Fisico-quimica de Cordoba. Universidad Nacional de Cordoba. Facultad de Ciencias Quimicas. Instituto de Investigaciones en Fisico-quimica de Cordoba; Argentina