Application Of micro-Raman Spectroscopy Research Articles

Non-destructive estimation of the cation composition of natural carbonates by micro-Raman spectroscopy

Carbonates play a crucial role in the water and carbon cycles of both geochemical and cosmochemical environments. As carbonates do not exist homogeneously with other minerals in rocks and sands of various sizes, an analytical method that simultaneously satisfies non-destructivity and high spatial resolution has been desired. Further, the ability of semi-quantitative analysis with carbonates-selectivity and without any pre-treatments is added, for its applicability would be extended to remote sensing for deep sea and outer spaces. Here, we focused on the application of micro-Raman spectroscopy, where the vibrational wavenumbers of the translational (T) and librational (L) modes of carbonates are sensitively related to their cation composition. By comparing the semi-quantitative information obtained by X-ray fluorescence spectroscopy, it was found that these vibrational wavenumbers are approximately linearly related to the cation composition. Consequently, a conversion matrix was proposed to estimate the cation composition from the T and L mode vibrational wavenumbers. This method is universally applicable to any cation composition in carbonates, with no background information on the analyte required. To improve the accuracy, conversion matrices were further optimized to three solid-solution series of carbonates. It is worth noting that the proposed conversion matrices are free from matrix effects and do not depend on the total amount of carbonate in a sample. Therefore, the proposed method provides a useful analytical basis for remote sensing of the cation composition of carbonates, both in terrestrial and extra-terrestrial environments.

Micro-Raman Characterization of Structural Features of High-k Stack Layer of SOI Nanowire Chip, Designed to Detect Circular RNA Associated with the Development of Glioma.

The application of micro-Raman spectroscopy was used for characterization of structural features of the high-k stack (h-k) layer of “silicon-on-insulator” (SOI) nanowire (NW) chip (h-k-SOI-NW chip), including Al2O3 and HfO2 in various combinations after heat treatment from 425 to 1000 °C. After that, the NW structures h-k-SOI-NW chip was created using gas plasma etching optical lithography. The stability of the signals from the monocrine phase of HfO2 was shown. Significant differences were found in the elastic stresses of the silicon layers for very thick (>200 nm) Al2O3 layers. In the UV spectra of SOI layers of a silicon substrate with HfO2, shoulders in the Raman spectrum were observed at 480–490 cm−1 of single-phonon scattering. The h-k-SOI-NW chip created in this way has been used for the detection of DNA-oligonucleotide sequences (oDNA), that became a synthetic analog of circular RNA–circ-SHKBP1 associated with the development of glioma at a concentration of 1.1 × 10−16 M. The possibility of using such h-k-SOI NW chips for the detection of circ-SHKBP1 in blood plasma of patients diagnosed with neoplasm of uncertain nature of the brain and central nervous system was shown.

Application of Micro-Raman Spectroscopy for the Quantitative Analysis of Vitrinite Reflectance in Medium and High Rank Colombian Coals

The structural changes and the degree of maturity of three Colombian coals from the Santander and Antioquia provinces were studied using a simple and fast curve fitting method of the RBS parameters (the distance between band G and band D), FWHM - G (total width at half the maximum of the G band) and AR (area of the Raman spectrum), obtained by deconvolution and band resolution of the Micro-Raman spectra. The results were compared by morphological and chemical analysis using a SEM scanning electron microscope coupled with a solid state X - ray EDS detector. A percentage of vitrinite reflectance (% Ro) of 4.3 %, 3.8 % and 0.07 % was obtained, a percentage of carbon by EDS analysis of 91.47 %, 87.78 %, 73.4 %, a morphological description by SEM analysis presenting smooth, rough surfaces and rough-lumpy and pore size between 0.7 µm - 0.8 µm, 1.3 µm - 1.5 µm and 0.2 µm - 0.7 µm for the anthracite, semi-anthracite and bituminous samples, respectively. The results showed that based on this method, it was possible to obtain a model that allows to rapidly analyze and characterize the coal. The results compare very well to those of Colombian coals normalized by other methods to improve the precision of the measurement. The modified method, however, did not offer an appropriate fit for the lower range coal and produced extremely low reflectance values. This effect is possibly related with the molecular structure of organic matter in coal or the presence of fluorescence interference.

Micro-Raman spectroscopy in medicine

Abstract A potential role of optical technologies in medicine including micro-Raman spectroscopy is diagnosis of bacteria, cells and tissues which is covered in this chapter. The main advantage of Raman-based methods to complement and augment diagnostic tools is that unsurpassed molecular specificity is achieved without labels and in a nondestructive way. Principles and applications of micro-Raman spectroscopy in the context of medicine will be described. First, Raman spectra of biomolecules representing proteins, nucleic acids, lipids and carbohydrates are introduced. Second, microbial applications are summarized with the focus on typing on species and strain level, detection of infections, antibiotic resistance and biofilms. Third, cytological applications are presented to classify single cells and study cell metabolism and drug–cell interaction. Fourth, applications to tissue characterization start with discussion of lateral resolution for Raman imaging followed by Raman-based detection of pathologies and combination with other modalities. Finally, an outlook is given to translate micro-Raman spectroscopy as a clinical tool to solve unmet needs in point-of-care applications and personalized treatment of diseases.

Mineralogical Characterization and Firing Temperature Delineation on Minoan Pottery, Focusing on the Application of Micro-Raman Spectroscopy

Ceramic objects in whole or in fragments usually account for the majority of findings in an archaeological excavation. Thus, through examination of the values these items bear, it is possible to extract important information regarding raw materials provenance and ceramic technology. For this purpose, either traditional examination protocols could be followed, focusing on the macroscopic/morphological characteristics of the ancient object, or more sophisticated physicochemical techniques are employed. Nevertheless, there are cases where, due to the uniqueness and the significance of an object of archaeological value, sampling is impossible. Then, the available analytical tools are extremely limited, especially when molecular information and mineral phase identification is required. In this context, the results acquired from a multiphase clay ceramic dated on Early Neopalatioal period ΜΜΙΙΙΑLMIA (1750 B.C.E.–1490 B.C.E.), from the Minoan Bronze Age site at Philioremos (Crete, Greece) through the application of Raman confocal spectroscopy, a nondestructive/ noninvasive method are reported. The spectroscopic results are confirmed through the application of Xray microdiffraction and scanning electron microscopy coupled with energy dispersive Xray spectrometry. Moreover, it is demonstrated how it is made possible through the application of microRaman (μRaman) spectroscopy to examine and collect crucial information from very small inclusions in the ceramic fabric. The aim of this approach is to develop an analytical protocol based on μRaman spectroscopy, for extracting firing temperature information from other ceramic finds (figurines) where due to their uniqueness sampling and analyses through other techniques is not possible. This information can lead to dating but also to firing kiln technology extrapolations that are very significant in archaeology.

Non invasive micro-Raman spectroscopy for investigation of historical silver salt gelatin photographs

At the end of the 19th century, photography rapidly spread and technical developments allowed for a wide range of artistic expressions. The application of micro-Raman spectroscopy on historical photographs permitted to identify the silver salt gelatin process and to characterize a typical surface alteration, known as “silver mirroring” or “silver tarnish”. The Raman spectra show diagnostic peaks of silver halide as an evidence of the use of the silver salt gelatin technique, whereas on the areas that are affected by silver mirroring the presence of silver sulfide could be attested by comparison with standards. This application resulted especially useful for those photographs with no evidence of silver tarnish although a silver salt technique had been used. Moreover, this study proves the suitability of micro-Raman spectroscopy on fragile materials such as photographs, without causing any damage.

Application of micro-Raman spectroscopy for fight against terrorism and smuggling

We report the results of Raman measurements on some common military explosives and explosives precursors deposited on clothing fabrics, both synthetic and natural, in concentration comparable to those obtained from a single fingerprint or mixed with similar harmless substances to detect illegal compounds for smuggling activities. Raman spectra were obtained using an integrated portable Raman system equipped with an optical microscope and a 785-nm laser in an analysis of 1 min . The spectral features of each illicit substance have been identified and distinguished from those belonging to the substrate fabric or from the interfering compound. Our results show that the application of Raman spectroscopy (RS) with a microscope-based portable apparatus can provide interpretable Raman spectra for a fast, in-situ analysis, directly from explosive particles of some μm 3 , despite the contribution of the substrate, leaving the sample completely unaltered for further, more specific, and propedeutic laboratory analysis. We also show how the RS is suitable for detecting illegal compounds mixed with harmless substances for smuggling purposes or for counterfeiting activities.

Structural features of human tooth tissues affected by high dose of external ionizing radiation after nuclear catastrophe of Chernobyl plant

The application of micro-Raman spectroscopy is discussed for the analysis of structural features of human tooth tissues affected by high doses of external ionizing radiation (0.5–1.7 Gy) after the nuclear plant catastrophe in Chernobyl in 1986. The results have shown significant changes in the mineral matrix of dental enamel that lead to the decrease of tooth enamel hardness. Destruction of the collagen chain of the organic matrix has been observed for dentin and cementum.

The identification of the pigments used to paint statues of Feixiange Cliff in China in late 19th century by micro-Raman spectroscopy and scanning electron microscopy/energy dispersive X-ray analysis

The application of micro-Raman spectroscopy (μ-RS) and scanning electron microscopy (SEM)/energy dispersive X-ray spectrometer (EDS) to the research of pigments collected from Statues of Feixiange Cliff No. 67 and No. 69 niche of Tang Dynasty in China is reported. Five kinds of pigments were found in the experimental data, including black (carbon), white (gypsum + quartz), blue (lapis lazuli) and green (Paris green + Barium sulphate). After synthesized in 1814, Paris green was reported for a large import as a light and bright green pigment to paint architectures in China from the late 19th century. The analyzed blue pigment demonstrated the similar Raman spectra to the Lâjvardina blue glazed ceramics, which indicated lapis lazuli was an artificial product. This confirmed the painting of Feixiange Cliff in the early Republic of China as the historical record, and also reveals that some pigments were imported from abroad.

Uniformity of Epitaxial Graphene on On-Axis and Off-Axis SiC Probed by Raman Spectroscopy and Nanoscale Current Mapping

Epitaxial graphene was grown on the surface of on-axis and off-axis SiC (0001) by solid state graphitization at high temperatures (2000 °C) in Ar ambient. The effect of the miscut angle on the lateral uniformity of the few layers of graphene (FLG) was investigated by combined application of micro-Raman spectroscopy and Torsion Resonance Conductive Atomic Force Microscopy, the latter method enabling a quantification of the FLG coverage on SiC with submicrometer lateral resolution. While the on-axis samples result in uniform coverage by thin (~ 3 monolayers) FLG, the coverage for off-axis samples is much less uniform, following closely the step bunching morphology of the SiC surface.

Micro-Raman spectroscopy stress measurement method for porous silicon film

Micro-Raman Spectroscopy (MRS) is an effective stress measurement method. Generally, the application of MRS for stress measurement requires the quantitative relationship between Raman shift and stress based on the material of the objects to be measured. In this paper, a theoretical investigation of Raman stress measurement for porous silicon (PS) material was presented. First, the mathematical expressions for the Raman shift and stress components of transversely isotropic material were deduced by analyzing the transversely isotropic characteristics of porous silicon material and applying the secular equation of lattice dynamics for diamond-type crystal. Meanwhile, the nanoindentation technique and digital speckle correlation method were introduced to detect the elastic moduli and Poisson's ratio of porous silicon material, respectively. Subsequently, the Raman shift to stress coefficients of porous silicon material, as well as their regularity varying with PS porosity, are achieved by substituting the material parameters determined in the experiments into the analytic relationship acquired through deductions. Using these coefficients, the distribution of residual stress along the thickness direction in the PS-film/Si-substrate structure was measured.

Applications of Micro-Raman Spectroscopy in Cultural Heritage – Examples from the Laboratory for Conservation Research of the Collections Centre of the Swiss National Museums

The paper reports on three applications of micro-Raman spectroscopy which were carried out in the Laboratory for Conservation Research of the Collections Centre of the Swiss National Museums. The first application addresses archaeological questions about three early mediaeval fibulae which were decorated with gemstones. The determination of different corrosion products on pigeon cameras by micro-Raman spectroscopy is described in the second part of this article. The last case study discusses an example from the field of preventive conservation where changes on metal coupons from the so-called Oddy test were analysed.

Characterization of stress in reinforcements in magnesium based squeeze infiltrated cast hybrid composites

Characterizing residual stresses in the reinforcement of cast composites has been studied in the present work. Micro Raman Spectroscopy is a unique tool for determining the strain on the reinforced fibres in ceramic/polymer/metal matrix composites. Stress induced Raman shifts can be used to determine the stress/strain in films, fibres and particulates in composites. In this paper, the application of Micro Raman Spectroscopy as a non-destructive technique in providing information on the compressional/tensile strain in reinforcements in metal matrix composites is investigated. Examples are taken from hybrid Mg based composites reinforced with carbon fibres, Mg 2Si in situ reinforcement, formed by the addition of Si in to the matrix and SiC particles. The studies on the strain measurements in as-cast condition and its comparison after thermal cycling of the composites using the bandwidth measured are discussed. Analysis of the bandwidth offers a tool to understand that the wavenumber shift is strain induced. With this, the compressional state of the fibres embedded in the matrix can be analysed.

Application of micro Raman spectroscopy to pharmaceutical formulations under controlled humidity

Application of micro Raman spectroscopy to pharmaceutical formulations under controlled humidity

Applications of micro-Raman spectroscopy in salicide characterization for Si device fabrication

This article demonstrates that micro-Raman spectroscopy is a very powerful technique for the study of a variety of problems related to metal salicides for Si device fabrication. In addition to its versatile nature and ease of use, this technique provides some unique capabilities that complement the commonly used tools for Si device characterization. Phase identification of the TiSi2 C54, C49, and C40 phases as well as NiSi and NiSi2 can be achieved easily using Raman spectroscopy. The phase transition process from NiSi to NiSi2 has also been successfully monitored. Raman band assignments for C40 TiSi2 and NiSi are also made in order to have a better understanding of the Raman spectra. Thickness measurement of ultrathin salicide films from 45 nm down to 6 nm has been accurately performed using attenuation of the Si Raman signal at 520 cm−1, and film uniformity can also be evaluated using the same peak. Local orientations of the NiSi grains are studied by the relative intensity of the NiSi Raman peaks with micron spatial resolution, which provides complementary information to the space-averaged x-ray diffraction result.

Fundamentals and applications of micro Raman spectroscopy to strain measurements in fibre reinforced composites

AbstractMicro Raman spectroscopy (MRS) can be used to measure strain in crystalline and semicrystalline materials with urn scale spatial resolution. It has been employed as a tool for measuring micromechanical behaviour in composites, and has contributed significantly to understanding of composite behaviour. An overview of the fundamentals of Raman spectroscopy and strain measurements using Raman spectroscopy as well as the instrumentation required is given. Studies using MRS to gain insight into the structure, elastic moduli, and failure modes of several types of fibres are presented. The micromechanical behaviour of single filament model composites is examined in detail including: residual stresses caused by processing; the stress transfer behaviour from the matrix to the fibre during loading; and the interfacial behaviour as a function of tensile and compressive loading, interface surface treatment, and environmental exposure. Finally, recent studies using MRS to study the fibre-fibre interaction and h...

Fundamentals and applications of micro Raman spectroscopy to strain measurements in fibre reinforced composites

Fundamentals and applications of micro Raman spectroscopy to strain measurements in fibre reinforced composites