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Journal of Raman Spectroscopy - published by
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An International Journal for Original Work in all Aspects of Raman Spectroscopy, including Higher Order Processes, and also Brillouin and Rayleigh Scattering.
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Translational relaxations of alcohol molecules in pure and water solution have been studied with polarized Raman spectroscopy. Temperature-dependent measurements show that the hydrogen-bonding (HB) and hydrophobic interactions control the translational motion. The hydrophobic interaction reduces the relaxation time more apparently for CH3 group than the skeleton motion. By adding water in alcohol liquids, translational motions generally slow down but show different concentration-dependent behaviors. Different mechanisms have been proposed to interpret these interesting observations, which are related to the HB networks in aqueous alcohols.
Significant enhancements in SERS signals were observed when the probing molecules of 4-mercaptobenzoic acid were adsorbed on the surface of Co-doped ZnO nanoparticles. The crystalline defects of the CoZnO nanoparticles caused by Co doping play an important role in the SERS activity.
Point-by-point standoff Raman measurements are made of distant samples using a precise pan-tilt system and then combined into a molecular species image of the distant target area.
Mixed populations of the bound substrate are identified in the active site of the Arthrobacter enzyme where the 4-hydroxy groups are present as 4-O− and 4-OH.
There are only a few small inorganic molecules of fundamental importance for which thecrystal structures are unknown. Carbonic acid (H2CO3) is one of them. Raman and IR spectra of the two known polymorphs of carbonic acid are reported here. Based on the data, local structural hydrogen-bonding motifs are presentedand suggested as building blocks of the crystal structures of α-H2CO3 and β-H2CO3.
Oxygen-induced microstructural changes in annealed nanocrystalline CeO2−x were investigated by X-ray diffraction and Raman spectroscopy. Analysis of structural and vibrational properties of annealed ceria demonstrated that microstrain changes, because of variable defect content, dominate over the crystallite size effect in annealed samples. A new Raman mode (S), ascribed to surface mode, originates from the defective and disordered structure.
This article presents the application of Raman and FT-IR spectroscopy for complex investigation of morphine, its metabolite and salts as well as a pharmaceutical product. Experimental analysis is supported by quantum-chemical calculations performed at the B3LYP/6–311++G(d,p) level.
Dental adhesive systems are used by dentists in restoration of teeth for bonding dental resins to enamel and dentin. The bonding systems used in this study were of the etch-and-rinse type. The purpose of this study was to compare the molecular structure of the adhesive–dentin and adhesive–enamel interface using Raman microspectroscopy. Raman images were obtained from univariate and multivariate methods. The dentin–resin interface was also studied using scanning electron microscopy and small-angle X-ray scattering.
We report the first in situ high-pressure Raman investigations of fully deuterated α-glycine up to ∼20 GPa. The spectral changes in the ND3+ and COO− modes indicate subtle structural rearrangements across 3 GPa. The decrease in the intensity of ND3+ torsional mode is found to be similar to that of undeuterated α-glycine. The pressure-induced stiffening of ND and CD2 stretching modes is discussed in the context of changes in the hydrogen-bonding interactions.
Raman spectra obtained at points along line scans of multilayer white paints show the change in composition between each layer and thus provide a method of discriminating optically identical paint samples.
Vibrational spectroscopy is used to evaluate molecular geometry in cyclic tetraynes via analysis of C≡C stretching bands that are activated when the center of symmetry in a polyyne structure is lost through bending of the ring.
Benzotriazole film formation was investigated on single-crystal and polycrystalline Cu surfaces with SHINERS. Potential-dependent spectra display reversible BTA film formation on polycrystalline Cu and irreversible film formation on single-crystal Cu.
First-order and multiphonon Raman active excitations are studied in YbVO3 as a function of temperature. Below T ≃ 170 K, new excitations are activated, following the G-orbital ordering and the concomitant orthorhombic to monoclinic phase transition. The observed phonon combinations around 1400 cm−1 with a dominant Jahn-Teller vibration ∼690 cm−1 are related to a possible orbiton-phonon coupling.
Two of the five possible conformers have been identified in the vibrational spectra of 2,2,3,3,3-pentafluoropropylamine. The enthalpy difference between these two conformers has been determined using variable temperature spectra of the sample dissolved in liquid xenon.
Differentiation of healthy and diseased tissues from the Brazilian octocoral Phyllogorgia dilatata was performed by in situ Raman Spectroscopy analysis. Spectral data of the healthy portion showed major vibrational bands at ca. 1520, 1160, and 1000 cm−1 due to ν(CC), ν(CC), and ρ(CCH3) respectively, corresponding to carotenoids. However, the diseased tissue, which has a purple pigmentation, showed bands at ca. 1500 and 1120 cm−1 attributed to polyenals belonging to psittacofulvin class.
The peak intensity from 55 nm Au@1.2 nm MnO2 NPs is about 10 times of that from 55 nm Au@4 nm SiO2 NPs. In SHINERS, the distance of the SERS-active core and the substrate is controlled by the thickness of the shell. Considering a much thinner shell thickness of MnO2 than that of SiO2, higher signal intensity obtained in the former system is reasonable. The improved signal intensity of Au@MnO2 SHINERS NPs has a strong advantage in increasing the sensitivity and decreasing the detection limit.
In this article, we report a high-pressure Raman spectroscopy study of the palmitic acid (PA, C form) from ambient pressure up to 21 GPa. The effects of hydrostatic pressure on the vibrational spectrum of PA are reported, and the data show that PA experiences a rich sequence of phase transformations. These changes in the crystal structure occur gradually as the pressure increases and they are related with the highly flexible crystalline structure.
Stability curve of the protein in the presence of 4 M urea was determined from the analysis of amide I band in the 260–360 K temperature range. Low wavenumber analyses have shown the important influence of solvent dynamics on cold and heat protein denaturations.
A detailed description of phase transitions occurring in the LixV2O5 active material in a composite electrode (0≤x < 2) is provided here for the first time using Raman spectroscopy. The successive emergence of the various phases governing the electrochemical properties of this cathode material is spectroscopically observed. This work demontrates that Raman spectroscopy constitutes a powerful tool to explore the structural changes induced by electrochemical Li insertion-extraction reactions in electrode materials for lithium batteries.
A combined Raman and AFM investigation was used to study in situ early Silurian enigmatic organic-walled microfossils classified traditionally to an informal taxonomic group named acritarcha. Based on the detection of internal spore-like bodies, acritarchs have been recently re-interpreted as vegetative cells of unicellular green algae (chlorococcales). To prove the identity of the internal bodies as spores, confocal Raman microscopy was applied to examine their chemical and mineral content.
A design extension of the only commercial Raman optical activity (ROA) spectrometer, the ChiralRAMAN which provides only scattered circular polarization ROA, is implemented for the simultaneous acquisition of all four forms of CP ROA.
The triple-resonant second-order Raman scattering mechanism in graphene is re-examined. It is shown that the magnitude of the triple-resonant contribution to the photon-G′ mode coupling function in graphene is one order of magnitude larger than the widely accepted two-resonant coupling. Enhancement of the order of 100 in the Raman intensity, with respect to the usual double-resonant model, is found for the G′ band in graphene.
FT-Raman and IR spectra acquired for four arginine vasopressin (AVP) analogs containing L-diphenylalanine (Dpa): [Dpa2]AVP, [Cpa1,Dpa2]AVP, [Dpa3]AVP, and [Cpa1,Dpa3]AVP were compared and analyzed. In addition, the FT-Raman spectra were compared to the corresponding SERS spectra recorded in an aqueous silver colloidal dispersion. The geometry of these molecules etched on the silver surface was deduced from observed changes in the intensity enhancement, broadness, and shift in wavenumber of the Raman bands in the spectra of the bound versus free species.
Using Raman spectroscopic mapping, the biochemical modifications associated with murine oocyte and early embryo development have been investigated, revealing a distinct asymmetrical organisation of macromolecules in the mature oocyte.
Raman spectroscopic studies of the zone-centre E2high optical phonon of a bent ZnO nanowire show a systematic red shift as the junction of the two arms of the nanowire is approached. The analysis of the Raman spectrum indicates the presence of tensile strain on the nanowire. Strain in the bent nanowire is also investigated using photoluminescence (PL) spectroscopy. Results of both Raman and PL study confirm that the bend nanowire is under tensile strain.
The Raman spectra of a number of MAX phases (Ti2AlN, Ti2AlC0.5N0.5, [Ti0.5,V0.5]2AlC, Ti2AlC, V2AlC, Ti3AlC2 and Ti3GeC2), mostly not spectroscopically investigated before, are measured and compared to the calculated mode wavenumbers via density functional theory. The 211 phases only show modes associated to atomic displacements of the ‘M’ and ‘A’ atomic planes, while the Ti3AlC2 and Ti3GeC2 also show modes that correspond with vibrations of the ‘X’ sublattice relative to itself.
The composition of Palaeolithic rock paintings from the Tito Bustillo and El Buxu caves (30 000–10 000 bp, Asturias, Spain) have been characterised by Raman microscopy with auxiliary techniques (scanning electronic microscopy/energy dispersive X-ray, infrared, X-ray diffraction and X-ray photoelectron spectroscopy). A supposed source of pigment is discarded. Possible relationships among pictographs from both caves are established.
The surface plasmons properties on the inverted square pyramidal pits array have been investigated experimentally and theoretically. The near-field scanning optical microscopy and the surface-enhanced Raman scattering mapping image showed that the plasmons mainly located in the cavity of the pits, which is consistent with the calculation result obtained using the finite element method. The plasmons coupling effect can improve the enhancement factors of the surface-enhanced Raman scattering substrates, but the field distribution remain unchanged.
Rosemary essential oils have been quantified in a complex matrix (olive oil) by means of multivariate calibration in Raman Spectroscopy. Experimental design has been carried out in order to optimize the Raman measurements. Different spectra pre-processing algorithms were evaluated and predicted concentrations were compared with Comprehensive Two-Dimensional Gas Chromatography.
Surface-enhanced Raman scattering of benzenesulfonamide and sulfanilamide show that they are adsorbed on silver nanoclusters as azanions. Benzenesulfonamide links to the metal through the nitrogen atom while sulfanilamide interacts in turn through the nitrogen atoms of the –NH2 and –SO2NH– groups. Additionally, it is found that the most enhanced surface-enhanced Raman scattering bands, especially the 8a;νring mode, are related to the presence of the charge transfer enhancement mechanism.
Soil bacteria of the genus Streptomyces are used as bioindicators for heavy metal contamination investigated via micro-Raman spectroscopy. Single cell Raman spectra are differentiated according to the varying Ni2+ concentration of the culture medium. The application of a support vector machine enables the classification spectra recorded from cells exposed to unknown Ni2+ concentration.
The quantification of ciprofloxacin in proprietary and generic tablets was investigated using a handheld Raman spectroscopic instrument. The potential of inbuilt and off-line algorithms for quantification were investigated. For off-line quantification, univariate regression and partial least squares regression methods were compared.
An extensive Raman investigation of few-layer graphene (FLG) structures, obtained using a plasma micro-jet technique, is presented. Raman spectra acquired using three different excitation wavelengths, both in the visible and in the deep UV range, are discussed in detail, with the aim both to obtain a complete structural characterization of the system, ascertaining in particular its stacking order properties, and to provide new, original and useful Raman data.
A nondestructive method has been reported to measure the high-temperature modulus of 3C-SiC using Raman scattering. The elastic modulus derived from the longitudinal optical phonon decreases linearly as the temperature increases. The values agree with previous measurements by other techniques.
By the means of surface-enhanced Raman scattering with Fourier transformation, we have developed a method for the quantification of adenine, xanthine, and hypoxanthine bases at their femtomolar concentrations.
A great diversity of organic osmotic solutes is found in nature. Thanks to the high concentrations in which these compounds are often present, Raman spectroscopy may be a useful technique for rapid analysis of such solutes both in individual organisms and in natural microbial communities in high-salt environments. In this paper, a database of Raman spectra of the most commonly encountered compatible solutes, as well as some less common ones, is presented.
Medieval Byzantine table pottery findings from Serbia have been analyzed by Fourier transform infrared, micro-Raman and scanning electron microscopy with energy dispersive spectroscopy. The vessels were made of noncalcareous clays and fired at temperatures between 700 and 900°C. The main type of transparent glaze was identified as lead-rich, while two samples were covered by an alkali–lime type of glaze.
Multi-wall carbon nanotubes (MWCNT) produced by the arc discharge between two graphite rods in liquid nitrogen have been investigated with the use of Raman spectroscopy and transmission electron microscopy (TEM). The effect of the applied voltage on the MWCNTs has been observed, in particular, as it concerns the size of the innermost and outermost diameters. The apparent discrepancies between the Raman and TEM results and the observation of a selective response of the MWCNTs to the excitation laser energy, similar to the case of single-wall CNTs, are explained by electronic structure calculation.
Yeastolate or yeast extract, which are hydrolysates produced by autolysis of yeast, are often employed as a raw material in the media used for industrial mammalian cell culture. Here, we demonstrate how surface-enhanced Raman scattering (SERS) can be used for the analysis of these materials.
Room temperature Raman spectroscopy of exfoliated Bi2Sr2CaCu2O8+δ single crystals with different thicknesses (from 6 nm to more than 150 nm) were collected and studied. The refractive index of Bi2Sr2CaCu2O8+δ single crystal was obtained by studying the intensity evolution of the Raman spectra based on interference effect. The Raman shifts of A1g (Bi), A1g (Sr), and A1g (OBi) modes were analyzed.
Additional SERS enhancement induced on bimetallic (Ag/Au) hierarchical structure is investigated using nanosphere arrays with Ag underlayer and Au overlayer. The significant dependency of SERS enhancement on the Ag/Au thickness ratio is confirmed. Importantly, compared with Au-array, the optimized bimetallic structures exhibit quasi-particles on the nanospheres with surpassing SERS (2.5×), approaching to that of Ag-array. The elevated SERS is attributed to the formation of effective hot-spots associated with enhanced roughness of the outer Au layer given by bimetallic deposition approach.
By performing scanning high-resolution confocal Raman microscopy of p-aminothiophenol and Rhodamine 6G molecules adsorbed to samples with different radii of shell curvature, we systematically investigate the applicability of hemispherical shell nanostructures for surface-enhanced Raman scattering and correlate the results with linear reflection spectroscopy. We trace the origin of strong Raman signal enhancements to electromagnetic hot-spots located in sharp grooves and crevices at the hemisphere shell junctions.
The spectral changes of the 144, 398, and 638 cm−1 TiO2 anatase Raman bands associated with various nanosize effects are evaluated. The critical size values of the nanocrystallites obtained from the peak position and FWHM assessment are found to be between 12.7 and 13.1 nm, whereas those achieved from the band asymmetry analysis, related to the phonon confinement, were between 10 and 11 nm. The use of this experimental approach, which can be applied for diverse nanostructures, indicated that the phonon confinement contribution to the overall size effects is more than 75%.
The Raman spectra and vibrational modes are reported for select machinable nanolaminate ternary carbides and nitrides known as MAX phases. The low-wavenumber modes are dominated by the Al atoms and the higher-wavenumber modes are dominated by the C and N atoms. Although the low-wavenumber modes are primarily dependent on the mass of the constituent atoms, the higher-wavenumber modes are a strong function of chemistry.
In situ Raman analysis was used together with Multivariate Curve Resolution with Alternating Least Squares (MCR-ALS) to measure the composition of the passive film on iron under pitting conditions in 0.05 M NaOH + 0.05 M NaCl. At the pitting potential the composition changes from mostly β-FeOOH and a Green Complex with smaller amounts of γ-Fe2O3 and γ-FeOOH, to δ-FeOOH and Green Complex, simultaneously with a reduction in water content. This change results in conditions which favour the rate of localised breakdown of the film by Cl− ions over the rate of re-passivation by water in the passive film. Relative amounts of δ-FeOOH, Fe3O4 and α-Fe2O3 on the surface adjacent to and in the centre of a ~100 µm pit, formed after being held for 1200s at anodic potential +0.3V in 0.05M NaOH + 0.05M NaCl.
A quick and reliable method, using Fourier transform–Raman and partial least squares analysis is used to determine percentage dissociation of mineral zircon to plasma-dissociated zircon. The Raman band at 477 cm–1 (Ag) proved to be consistent and reliable for implementation in industrial situations. The ease of implementation is a vast improvement on previous wet chemical methods that are wasteful, time consuming, and use highly corrosive acids such as hydrofluoric acid.
In this work, 46 tile/ceramic shards of unknown origin, from the vaults of Topkapı Palace Museum, were examined using scanning electron microscopy-energy dispersive X-ray spectroscopy and micro-Raman spectroscopy techniques. Results of both techniques were evaluated together for differentiation of Ottoman tiles.
This paper describes a surface-enhanced Raman scattering study regarding the functionalization of Au and Ag NPs with the diphenyl disulfide, diphenyl diselenide, and diphenyl ditelluride. Functionalization took place with the cleavage of the chalcogen–chalcogen bond, and the detected differences in the spectra were assigned to the distinct stretching frequencies of the carbon–chalcogen bond and its relative contribution to the ring vibrational modes
Surface-enhanced Raman spectra were measured for melamine and other chemicals at 1550 nm laser excitation. The results are compared with spectra at 785 and 1064 nm using similar Raman optical systems and the same surface-enhanced Raman scattering substrate.
Values of 2.8 ± 0.3 × 10–12, 2.0 ± 0.2 × 10–12, and 0.8 ± 0.1 × 10–12 cm.g–1.s2 were measured for the xxxx, xxyy, and xyyx components of |3χ(3)|, respectively, using coherent anti-Stokes Raman scattering. The Raman cross-section has been determined to be 3.1 ± 0.6 × 10–29 cm2 per molecule. The Raman linewidth (full width at half maximum) was measured to be 2.4 ± 0.3 cm–1 with normal Stokes Raman scattering.
Ag nanoparticles synthesized on porous silicon samples were studied and applied as surface-enhanced Raman scattering (SERS) substrates. SERS activity was tested using Cy5 dye verifying an enhancement factor up to 107. CGIYRLRS peptides were chemisorbed on the Ag nanoparticles with the plasmonic resonance tuned at the excitation energy. Such oligopeptides were used as baits for a specific polyclonal antibody. The overall Raman enhancement allowed to evidence a good selectivity to the target analyte as required by most of the SERS applications on biological assays.
An extensive micro-Raman study of prehistoric rock paintings found in Hararghe region, Ethiopia, was conducted to evaluate the production skill of the local artists and the period of production of the discovered paintings. The pigments used were hematite, calcite or gypsum, and carbonaceous material. A green earth pigment was also investigated. Raman mapping evidenced that Ca-oxalate, found on red and white samples, is ascribed to the use of an organic stuff to spread properly the pigments on the substrate.
For the binarymixture in which both proteins do not contain chromophores, variations in the intensities of surface-enhanced Raman scattering signals with changes in relative concentration of the two kinds of proteins is largely proportional to the relative concentration of the protein mixture. However, when another binary mixture is investigated, in which one protein contains chromophore while the other protein does not, the surface-enhanced Raman scattering intensities of the protein mixture displays a bell-shaped variation versus the changes in the mixture composites.
Discrimination of ancient Asian bronzes and brasses is complex because the copies have been made since ancient times. A selection of 30 Japanese and/or Chinese Bronzes are studied on-site in the storage and exhibition rooms of the Cernuschi Museum in Paris. Attempts are made to identify specific Raman signatures of the patina to detect similarity in a nondestructive procedure and to discuss the relationship between the patina phases and the bronze composition.
Analyses of low-wavenumber Raman, X-ray diffraction and transmission electron microscopy data show that heat-treatments of sol–gel derived SiO2–SnO2 glass ceramics result in the formation of SnO2 nanoparticles with sizes of about 7 nm. Although the presence of the particles results in residual matrix porosity, a total phase separation occurs with the silica matrix serving to control the growth of the SnO2 nanocrystals.
The Raman and surface-enhanced Raman scattering (SERS) spectra of l-proline (Pro) and trans-4-hydroxy- l-proline (Hyp) were registered. SERS spectra were recorded by using Ag colloidal obtained from hydroxylamine reduction agent. The accommodation time of Pro and Hyp in the colloidal solution resulted fundamentally in obtaining SERS spectrum. The spectroscopic results are supported by quantum chemical calculations, performed by using extended Hückel theory of the title compounds interacting with an Ag cluster model.
A repeatable detection of unperturbed water-soluble cationic porphyrin 5,10,15,20-tetrakis(1-methyl-4-pyridyl)21H,23H-porphine (TMPyP) at a very low concentration using surface-enhanced resonance Raman scattering spectroscopy is reported. No post-modification of Ag nanoparticles prepared by modified Tollens method is necessary to observe the surface-enhanced resonance Raman scattering signal of free-base TMPyP. Possible reasons of hindered metalation and detection of a very low TMPyP concentration are discussed.
Raman spectroscopy has been used to investigate different conformational states of insulin: the native form and several structurally modified states with different extent of denaturation induced by thermo-chemical treatment and by applying very high pressure (up to 8 GPa) using a diamond anvil cell. High-pressure results confirm the peculiar strength to volume compression of insulin and largely extend the pressure range of its structural stability. Above 4.2 Gpa, insulin undergoes an irreversible transition to a new conformational state.
The application of chemometric techniques to Raman spectra to study natural aged lipidic paint binders has been evaluated. Model samples of the pure binders (linseed, poppy-seed and walnut oils and egg yolk) and of binary mixtures were used. These model samples were left to age naturally for six years and further characterized by Raman spectroscopy. A comparative study of the Raman spectral features before and after ageing process was carried out. This showed changes mainly in the bands located at 1267, 1655 and 3011 cm–1, which correspond to vibrations in cis double bonds. Multivariate analysis was performed by applying principal component analysis and partial least-squares discriminant analysis on the corresponding Raman spectra to test whether spectral differences allowed samples to be distinguished on the basis of their composition.
Considering that water plays a fundamental role in the generation of atmospheric inorganic particles, Raman spectroscopic studies of two specific systems were performed. It was observed that KNO3 crystallizes from aqueous solution at 20°C in phase III. The polarized Raman spectra of synthetic darapskite were recorded and bands assigned.
Raman spectroscopy was applied on a depth profile of porcine adipose tissue (from skin to meat) with the purpose of (1) discriminating between fat layers and (2) estimating the total degree of unsaturation (iodine value) as a function of fat depth and fat layer. From principal component analysis on standard normal variate preprocessed Raman spectra (1800–800 cm–1), it was possible to discriminate between the outer and the inner backfat layer.
A Raman optical activity (ROA) spectroscopic study on methyl lactate and related molecules provides detailed structural information of hydrogen bonding in homochiral dimers and reveals different behaviors of optical activity tensor invariants for the intra- and inter- molecular hydrogen bonding motions
On the basis of a conducting polypyrrole nanofiber film, we demonstrate a convenient route for the simultaneous synthesis and immobilization of Au nanoplates that exhibit highly enhanced Raman activity.
A complete Raman spectral characterization of monobromoindigo, a component of a historically important colorant named Tyrian purple, was carried out at 488 and 785 nm and the results were compared to the analogous data collected from indigo under the same conditions. A detailed assignment of the Raman lines was obtained using density functional theory calculations, which revealed the similarity and differences between experimental monobromoindigo and indigo spectra.
Composite fibres based on vanadium oxide are synthesised by the combined sol–gel/electro-spinning method. The effect of calcination at different temperatures (300–500 °C) on their microstructure and composition is investigated in view of the possible use of the fibres in gas sensor fabrication.
Temperature-dependent phonon anomalies in pyrochlore titanates (A2Ti2O7) decrease as Ti4+ is replaced by bigger ions, thus indicating a decrease in phonon–phonon anharmonic interactions.
A set of chromolithographs from the 19th century was analysed by Raman spectroscopy assisted with energy dispersive X-ray fluorescence and Fourier-transform infrared spectroscopies. The study showed that although the range of substances used for its elaboration was relatively limited, the use of some complexes and unusual admixtures of primary pigments were identified.
The mineral brushite has been synthesised by mixing calcium ions and hydrogen phosphate anions to mimic the reactions in a cave. The Raman spectra of the synthesised brushite were compared with that of the natural cave mineral.
An experimental procedure is presented to demonstrate the acquisition of reproducible surface-enhanced Raman scattering spectra of hydroxyproline and its deuterated-d3 analogue.
A series of Mg-bearing synthetic amorphous calcium carbonates were characterized by Raman spectroscopy. The spectra show a systematic increase in carbonate ν1 peak position from the control samples that contain 0.0 mol % MgCO3 to samples that contain up to 43 mol % MgCO3. The Mg content is equally well-predicted by a correlation with the ν1 full width at half maximum.
A first-order, reversible phase transition is first found to proceed in cordierite at about 4.5 GPa. It is preceded by disordering of the framework and intrachannel H2O subsystem at P > 4 GPa. The shifts amplitudes of different framework modes indicate the predominance of deformation over contraction of the framework polyhedra upon this transition. The disordering of H2O molecules in new phase is likely a consequence of distortion of channel-forming framework elements, which is supposed to be a driving force of this transition.
The signal amplification observed in surface-enhanced Raman scattering is highly influenced by the interparticle separation in metallic colloidal-based substrates. Microwave absorption is shown to be a sensitive probe to monitor silver nanoparticle sintering as a function of temperature. Because the microwave losses occur predominantly at the weak electrical links between nanoparticles, microwave absorption monitoring can serve as a guide in determining thermal annealing treatments to optimize surface-enhanced Raman scattering substrate performance.
Raman spectroscopic investigation was done for normal, carcinoma in situ, and invasive squamous cell carcinoma (SCC) of tongue tissues. In the SCC, an enhancement (reduction) in Raman bands associated with tryptophan (keratin) compared to the normal tissue was observed. This study shows the diagnostic potential of Raman spectroscopy for detection and progression of SCC in the tongue.
The results on structural damage in germanium wafers caused by hydrogen and helium implants of typical doses used in Smart Cut™ technology (4−8x1015 atoms/cm3) are investigated using Raman mapping and spreading resistance profiling techniques. Raman line-mapping measurements were performed up to the depth of ~400 nm into Ge substrate (well beyond the limit of visible light penetration depth) using a bevelling technique. From analysis of the Ge–Ge Raman peak it was found that implantation of H and He introduced a different type of stress, tensile and compressive, respectively, and significant structural damage with maximum at the projected range. The crystalline structure after implantation is completely recovered when annealed at 600 °C for both type of implants.
Silver nanowires (diameter = 200 nm) are synthesized by electrochemical deposition in the pores of an alumina mask. After dissolution of the alumina template, a single silver nanowire is nanomanipulated and attached to an atomic force microscopy (AFM) cantilever by focused electron beam induced deposition. These nanowire-functionalized AFM-tips present a strong and reliable tip-enhanced Raman spectroscopy effect and very good AFM imaging capabilities. This method is capable of producing nanowires of different metals with diameters down to 50 nm and with various shapes.
Raman spectra of Rb2KTiOF5 crystal have been obtained and analyzed at temperature range from 77 to 297 K, and under hydrostatic pressure till 4.2 GPa (at T = 296 K). The experimental results are compared with the quantum-chemical simulation of TiOF5 pseudo-octahedron. Phonon spectra for several ordered phases of Rb2KTiOF5 were simulated within ab initio generalized Gordon – Kim model to interpret effects of lattice ordering. Under ambient conditions the spectra exhibit orientation disordering in the cubic phase. Cooling below the phase transition temperature (215 K) partially orders the structure. The isotropic perovskite-like phase was found to undergo first-order transition into low-symmetry anisotropic phase at about 1 GPa. The spectra of high-pressure and low temperature phases are different. Further compression up to 4.1 GPa did not disclose any effects associated with phase transitions.
The SERS of R6G adsorbed on the roughened Ag substrate developed in this work exhibits a higher intensity by ca. 4-fold of magnitude, as compared with that of R6G adsorbed on a roughened Ag substrate prepared in a chloride-containing solution, which were generally shown in the literature.
Shifts of the band position of the 462 and 1111 cm–1 Raman lines of berlinite with pressure and temperature were calibrated for use as pressure sensor for diamond-anvil cell experiments. Pressure can be determined from changes in the difference of both band positions, with the advantage that this method is independent of spectrometer drift and spectral resolution. The attainable precision is comparatively high because of the large pressure-induced and the fairly small temperature-induced changes in this difference.
Combining membrane electrophoresis with surface-enhanced Raman scattering (SERS) spectroscopy, serum proteins were first purified and then mixed with silver nanoparticles to perform SERS spectral analysis. Therefore, the spectral signatures were enhanced to high-fidelity SERS signatures because of the purification procedure of the first step. We used the method to analyze blood plasma samples from nasopharyngeal cancer patients (n=43) and healthy volunteers (n=33) for cancer detection. Principal components analysis of the SERS spectra revealed that the data points for the cancer groups and the normal group form distinct, completely separated clusters with no overlap. Therefore, the nasopharyngeal cancer group can be unambiguously discriminated from the normal group, i.e., with both diagnostic sensitivity and specificity of 100%. These results are very promising for developing a label-free, noninvasive, and reliable clinical tool for rapid cancer detection and screening.
The temperature dependence of Raman spectra for SrBi2−xNdxNb2O9 ceramics has been measured. Many anomalous changes were observed and discussed in detail. The TC decreases from ~710 to 550 K with the Nd composition because of the reduced distortion extent and tilting angle of NbO6 octahedron.
A database was compiled on the Raman spectra of about 175 glass trade beads and classified according to the type of glass matrix and pigments used as colouring agents. The results raise questions about the last occupation date of the Mapungubwe hill in South Africa.
Time-resolved resonance Raman results show that the 2-chloro substituent reduces the hydrogen abstraction ability of the substituted benzophenone triplet while the 3-chloro, 4-chloro and 4,4′-dichloro ones have little influences on their triplet properties and reactivities. The experimental spectra were indentified and analysed with the aid of density functional theory calculations.
Raman spectroscopic studies of a few Japanese art objects have been performed by using a portable Raman spectrometer constructed with liquid crystal tunable filters as dispersive elements. Interesting information has been obtained from Raman spectra observed from ukiyo-e's (Japanese woodblock prints) and their woodblocks
Single crystal Brillouin and Raman scattering measurements on NH3 in a diamond anvil cell have been performed under pressures up to 26 GPa at room temperature. The pressure dependencies of acoustic velocity, adiabatic elastic constants, and bulk moduli of ammonia from liquid to solid III and solid IV phase have been determined. In Raman spectra the very weak bending modes ν2 and ν4 for orthorhombic ammonia are both observed at room temperature. Both Brillouin and Raman spectra reflect a possible isostructural phase transition near 12 GPa, which is consistent with early X-ray diffraction studies.
Point-to-point micro-Raman spectroscopy and X-ray diffraction (XRD) technique were employed to characterize mineralogical content of 27 pottery artifacts. Twenty-six different minerals were identified by their Raman spectra and 13 minerals were identified by XRD. The results obtained from the Raman and XRD spectra for the most abundant minerals in the investigated pottery bodies match quite well, while the identification of the less abundant minerals in the clay matrixes, from the XRD data, was very difficult, if at all possible.
Detailed experimental and theoretical Raman investigations of quantum confinement and laser-induced local thermal effects have been performed on hydrogenated nanocrystalline silicon with different nanocrystal sizes. We have shown that the phonon dynamic behavior correlates well with the phonon density of states in Si nanocrystals.
Layer silicates F- and OH-apophyllites, KCa4Si8O20(F, OH)·8H2O, have been investigated by Raman spectroscopy at hydrostatic and nonhydrostatic pressures up to ~8 GPa in a diamond anvil cell in a methanol–ethanol medium. At hydrostatic compression, apophyllites retain their crystalline states (i.e. no amorphization) up to 5 GPa so that the wavenumbers of most bands exhibit linear dependences on pressure. However, nonhydrostatic compression with additional uniaxial loading induces nonlinear dependences of these wavenumbers, widening bands and posterior amorphization of apophyllite.
A simple analytic model of linear polarization stimulated Raman scattering spectroscopy in isotropic media is developed. In this scheme, the pump and Stokes beams can have arbitrary and independent linear polarization states, and the stimulated Raman scattering signal is analyzed along two perpendicular directions. This model enables us to measure Raman depolarization ratio of solutions in a simple way.
The Raman spectrum of a pure-phase U4O9 is for the first time completely described and interpreted. The U4O9 Raman spectrum derives from the well characterised one of UO2. Besides reminiscent modes of UO2, a band at 630 cm-1, which has a specific response to polarised light, was interpreted as characteristic of clusters of interstitial oxygen atoms.
We have investigated the suitability of five standard silver colloids for future ultra-sensitive SERS experiments. Stability, surface chemistry, presence of spurious spectral features and SERS activity were studied.
The vibrational properties and the crystal structure of submillimetre inclusions of unusual habit incorporated at different depths in a tanzanite gemstone have been investigated by means of confocal micro-Raman spectroscopy. The observed spectral features were unambiguously identified as specific markers of hematite (α-Fe2O3). The assignment has been inferred by comparing our experimental findings with the literature data recorded either in single crystals of hematite or in other iron oxides and oxyhydroxides.
PVA-Ag GPs grown on the surface of the common Al substrate obtained by electrochemical deposition is used as active SERS substrate in the analysis of DNA. The activity of this substrate is checked by recording the SERS spectra of thymine solutions with different concentrations.
We present here a method to normalize spectra as well as estimate sample thicknesses based on a reference component present in the basal cell culture medium when we perform spectroscopy on colonies of living cells.
Individual phospholipid vesicles, with membranes containing diacetylene functional groups in the acyl chains, were optically trapped and polymerized by a UV lamp, while observing structural changes in the vesicle bilayer using confocal Raman microscopy. Time-dependent changes in the Raman spectra revealed the kinetics of the polymerization reaction and formation of two distinct polymer forms. Thermochromic behavior of the two polymer forms was investigated from temperature-dependent changes in the Raman spectra of a polymerized vesicle.
The chemical composition of the black stains threatening the rock-art paintings of Lascaux Cave, Montignac, France was studied using surface-enhanced Raman spectroscopy (SERS). The stains are mainly composed of the melanin from the fungus Ochroconis sp. and the faecal pellets of the collembolan Folsomia candida. SERS is a useful technique for revealing the structure of unknown macromolecules in cultural heritage research.
We provided the design of a three-dimentional surface-enhanced Raman scattering-active substrate through the supramolecular self-assembly of Au nanoparticles into the nanopores of anodic aluminum oxide templates. With the method, large numbers of metal nanoparticles were successfully loaded into the anodic aluminum oxide channels in an aggregation form, which supported more ‘hot spots’ to bring stronger surface-enhanced Raman scattering effect.
A method employing photochemical hole-burning is used to compare the Raman enhancement distributions of benzenethiol adsorbed on substrates optimized for 532 nm laser excitation, consisting of close-packed or nonclose-packed nanospheres. The close-packed substrate has a small number of sites with enhancements in the 108–1010 range not present on the nonclose-packed substrate.
Ag dendrites with different growth direction exhibited different surface- enhanced Raman scattering effect: the Ag dendrites growing along [100] direction have the best effect; the ones with [111] direction the middle, and the ones with [110] direction the worst.
The causes of the variability in the mechanical behaviour of various silks obtained from silkworms (Bombyx mori, Antheraea/Tussah) and spiders (Nephila madagascarensis) have been studied by tensile uniaxial tests and Raman microspectrometry of the νN–H and O–H bands. Five stress/strain behaviours are evidenced and correlated to the water content and short-range disorder.
The structural evolution of high-energy (50 MeV) lithium ion (Li3+) irradiated undoped semi-insulating GaAs (SI-GaAs) and chromium doped SI-GaAs (GaAs:Cr) have been investigated by Raman measurements. We have observed that high-energy Li3+ irradiation causes amorphization beyond a fluence of 3 × 1013 ions/cm2 in undoped SI-GaAs, but the same fluence of irradiation does not affect the crystallinity in GaAs:Cr appreciably.
This study demonstrates for the first time in vivo Raman spectroscopy in the fingerprint region (800–1800 cm−1) of the oral cavity. High-quality in vivo Raman spectra could be acquired in real time (<0.5 s) from 20 patients. Difference spectra and semiquantitative non-negative constrained least squares minimization of reference biochemicals disclose that inter-anatomical variability is significant and should be considered as an important parameter in the interpretation and rendering of Raman diagnostic algorithms for oral tissue diagnosis.
Soil samples were collected from both urban and rural environments. This study demonstrates how, with the use of oxidative preparation methods, Raman spectroscopy can be used to successfully discriminate between soil types using mineralogy as well as the organic and water-soluble fractions of soils.
This is the first attempt to characterize Iberian pottery from the La Vispesa Spanish archeological site using Raman microspectroscopy. Pigments and crystalline inclusions of different minerals in the ceramic pastes have been identified. Firing conditions and provenance markers for the clays are discussed.
The paper presents a general expression for the surface-enhanced hyper Raman cross-section of symmetrical molecules and selection rules for their contributions. Analysis of the SEHR spectra of pyrazine and pyridine allowed us to explain all their features.
The aspect ratio of the tip can play a significant role in the efficiency of TERS probes with the electrostatic field arising from the lightning rod effect having a substantial role in the observed TERS effect.
A linear relationship is observed between the integrated intensity ratio of the OH stretching envelope of water to the symmetric stretching band of the nitrate ion and the molar water-to-solute ratio. It indicates that the Raman scattering cross sections of NO3− and H2O are insensitive to the structures of both ion pairs and hydrogen bonding, which is important for quantitative analysis with Raman intensity.
Raman and Raman optical activity (ROA) spectra of (+)- and (−)-bornyl acetate (BA) have been measured and calculated by the DFT/B3LYP/6-311 + + G** method. ROA spectra were found to be in good agreement with the experimental data and their detailed vibrational assignment is reported for the first time. Further, the combination of Raman and ROA spectroscopy as well as DFT calculations was successfully applied not only to detect BA, the main constituent of pichtae essential oil, but also to determine its specific enantiomer present in the investigated oil samples.
Electromagnetic coupling between localised plasmons on metal nanoparticles and the strong localised fields on a micro-structured surface is demonstrated as a means to increase the enhancement factor in surface-enhanced Raman scattering (SERS).
We propose and investigate a new technique for comparing two Raman active samples. The method employs optical interference of the signals generated via coherent anti-Stokes Raman scattering of broadband laser pulses with noisy spectra. It does not require spectrally resolved detection, and no prior knowledge about either the Raman spectrum of the samples or the spectrum of the incident light is needed.
We report SERS marker bands for methylated and nonmethylated ribonucleosides, using a variety of Ag-colloidal systems, that distinguish between each of these species. The roles of aggregating agents on these SERS spectra, and in regulating the interactions between the nucleosides and the colloid surfaces, are shown to be important.
We have examined the surface characteristics of Ag-doped Au nanoparticles by means of the surface-enhanced Raman scattering of 2, 6-dimethylphenylisocyanide and 4-nitrobenzenethiol. It clearly indicates that the surface content of Ag increases almost linearly as a function of overall mole fraction of Ag and, once the Au/Ag nanoparticles reach 5 mol% of Ag, their surfaces are fully covered with Ag and show the same surface characteristics of pure Ag nanoparticles.
Relations between Mg# [ = 100 Mg/(Mg + Fe)] and Raman wavenumbers of olivine samples are analyzed for five bands in the 800–1000 cm−1 spectral range for the Mg# range of 100–62. The wavenumber of each peak shifts linearly with Mg#. An equation describing these relations enables us to determine Mg# with geologically satisfactory precision of ± 1 Mg# (1σ).
A novel ultralow wavenumber filtering module, which provides access to ultralow wavenumber Raman modes on single-grating spectrometers, is employed to study the folded longitudinal acoustic (LA) phonon modes of InxGa1−xN/GaN superlattices (SLs) grown by molecular beam epitaxy. The wavenumber behavior of the folded LA modes is well reproduced by elastic continuum theory. The wavenumber of the doublets is used to evaluate the period of the SLs.
The dynamic behavior of highly oriented ferroelectric Sr1.9Ca0.1NaNb5O15 thin films has been investigated by Brillouin light scattering over a wide temperature range between 25 and 450°C. The width of the central peak decreases steadily upon cooling from ∼400°C to Tc and shows little subsequent change within the ferroelectric state, indicating an increase of the number of polar nanoregions (PNRs) and a slowing down of their dynamics. The evidence for this diffuse phase transition provided by Brillouin scattering is in agreement with results obtained from the temperature-dependent dielectric permittivity, refractive index, and Raman spectra.
We have developed a planetary environment and analysis chamber to perform in situ multiple spectroscopic measurements on geological samples under planetary-relevant environmental conditions, and to support future planetary missions, with particular interest on Mars. Coordinated spectroscopic sensing on the same geological samples under well-controlled atmospheric conditions establishes a way to link the results from the laboratory experiments to the spectral data obtained by landed and orbital planetary exploration missions.
The ranitidine hydrochloride polymorph profile of tablets and capsules was quantified using transmission and Fourier transform Raman spectroscopy. More accurate predictions of ranitidine hydrochloride form I content in both tablets and capsules were obtained when using transmission Raman spectroscopy.
We report here the applicability of Raman microspectroscopy to the particular case of polished carbon materials, and show that meaningful Raman structural characterization of such materials is still possible by using an appropriate parameter.
Surface enhancement factors (EFs) of copper surface/substrates formed by different preparation procedures (electrochemically prepared large substrates and colloidal systems) in FT-SERS spectroscopy were studied. Surface morphology of the large substrates was studied using atomic force microscopy. The size distribution of colloidal nanoparticles was monitored by dynamic light scattering. The EF values are in both cases more than 105 for FT-SERS spectra, demonstrating the fundamental role of nanostructured copper as a substrate material at the excitation wavelength (1064 nm) used.
The conformational polymorphism of chlorpropamide was investigated applying Raman spectroscopy combined with a detailed analysis of the crystal structure and quantum mechanical calculations. The temperature dependence of the Raman spectra of form I confirmed the existence of a low-temperature polymorph.
The mineralogy of the body and glaze compositions of unmarked early English stetitic porcelain wares has indicated the presence of both enstatite and forsterite in one and enstatite and diopside in the other. Different lead-based glazes and pigment compositions were used. The vase has now been attributed to Worcester (ca. 1753–1754) manufacture and the coffee cup to Bow (ca. 1746).
Neo-angiogenesis stimulation and hypercellularization are the result of shock wave treatment. The present work provides a first approach of structural aspects resulting of collagens type I and III by the shock wave treatment.
A bronze Pan (water vessel), dating back to the 4th–3rd century BC, was excavated at Jiuliandun in Hubei Province, central southern China, in 2002. The Pan attracts wide attention among the Chinese archaeologists and conservators for its uniqueness in style and color, which turns out to be due to a black-brown film of about 1 mm thickness. In the present work, a combined use of X-ray fluorescence (XRF), micro-Raman, and X-ray diffraction (XRD) was employed to determine both chemical and physical compositions of the Pan's film.
The results are summarized as follows: (1) The film, as XRF analysis indicates, has high concentrations of chromium (Cr) and iron (Fe); (2) Both Raman and XRD analyses suggest that the element Cr probably exists in the film mainly in the form of chromium oxide (Cr2O3). Raman analysis also implies the presence of PbCrO4·PbO in the film; (3) XRD analysis suggests that the element Fe exists in the film in the form of magnetite (Fe3O4).
The combined use of micro-Raman, WDXRF, and XRD has enabled us to investigate and determine the chemical and physical compositions of the brown-black film covered on a bronze Pan (water vessel) that was excavated from the Jiuliandun tombs (∼300 BC), Hubei Province, central southern China. Based on the analytical results and with reference to the records in Chinese historical literature, we deduce that, as early as in the 3rd century BC, people in central southern China might have discovered and intentionally used chromium minerals for bronze treatment (casting, decoration, etc.). The source(s) of chromium minerals used in this period might be Cr-spinel minerals from meteorites.
Raman spectroscopy is used to investigate six French miniatures on ivory or paper dating back to the 18th and 19th century. Different operative conditions and parameters were tried in order to assess the optimal procedure of analysis for this fragile kind of work of art through their protective glass. The results obtained for the different pigments and the relative criteria of dating are presented.
Thermally induced reversible and irreversible denaturation of lysozyme in salt-free aqueous solution were followed by Brillouin and Raman scattering and FTIR absorption spectroscopy. The characterization of the protein system, from the conformation of the polypeptide chain to the exposure of side chains to the solvent and the arrangement of the solution network, was achieved in the 25–85 °C range.
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CH3 group than the skeleton motion. For alcohol–water mixtures, the increase of water concentration generally slows down the relaxation process in a non-monotonic behavior. However, the trend stops at a certain point and the motion of alcohol molecules becomes faster when the alcohol concentration further drops. Different mechanisms have been proposed to interpret these observations, which might be helpful to gain deeper insight into the HB networks of alcohols with water. Our study strongly illustrates that Raman spectroscopy can be applied to the study of fast translational motion of molecules in HB systems. Copyright © 2011 John Wiley & Sons, Ltd.
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O double bond and C-S regions, suggesting that the hydrolyzable thioester group is rigidly bound in the active site in a syn gauche conformation. Copyright © 2011 John Wiley & Sons, Ltd.
