Molecular structural analysis of noncarious cervical sclerotic dentin using Raman spectroscopy

Molecular structure of the sclerotic dentin in noncarious cervical lesions (NCCLs) including both the inorganic phase and organic phase was investigated using Raman spectroscopy. It was found that NCCL sclerotic dentin was hypermineralized with the mineral/matrix ratios 2–3 times higher than those of normal dentin, which was caused by both the increase of mineral content and decrease of organic matrix (collagen) content in the sclerotic dentin. For the inorganic phase, the phosphate band (PO₄³⁻, ν₁, symmetric stretching vibrational mode) in NCCL sclerotic dentin was shifted from 960 to 963 cm⁻¹, and the width of this band was decreased from 16.4 to 10.4 cm⁻¹, indicating that the degree of mineral crystallinity in NCCL sclerotic dentin was higher than that of normal dentin. In addition, the carbonate content in the mineral of NCCL sclerotic dentin was less than that of normal dentin. As compared to the inorganic phase, the changes within the organic phase were not dramatic. However, the changes in collagen cross‐link density along with other spectral changes were still detectable. There was a noteworthy reduction in the ratio of nonreducible to reducible cross‐links in the NCCL sclerotic dentin, indicating that cross‐link breaks occurred in the collagen matrix of the lesions. Copyright © 2009 John Wiley & Sons, Ltd.     

The influence of divalent metal ions on low pH induced LacDNA structural changes as probed with UV resonance Raman spectroscopy

UV (275 nm) resonance Raman spectra of LacDNA 22‐mer duplex [d(TAATGTGAGTTAGCTCACTCAT) · d(ATGAGTGAGCTAACTCACATTA)], which contain protein binding sites within the E. coli lac promoter, were measured at two pH values (6.4 and 3.45) in the absence and presence of Mn²⁺ and Ca²⁺ metal ions, respectively. Also, the UV (275 nm) resonance Raman markers of the corresponding oligonucleotide d(TAATGTGAGTTAGCTCACTCAT) and of its complementary anti‐sense strand d(ATGAGTGAGCTAACTCACATTA) were established and tentatively assigned. Large changes in the UV (275 nm) resonance Raman spectra of LacDNA duplex were observed at pH 3.45 as compared with the corresponding spectrum at pH 6.4, in the absence of divalent metal ions and at low concentrations of Ca²⁺ ions, respectively. Major changes comprise: adenine protonation, GC base pair protonation, DNA bases unstacking and changes in the hydrogen bonding strength between the strands of different LacDNA complexes, respectively. Divalent metal ions (Mn²⁺ and Ca²⁺) were found to inhibit LacDNA protonation even at low concentrations. Manganese(II) ions are much more effective in this regard, as compared with calcium(II) ions. Binding of Mn²⁺ ions to N7 of guanine and, possibly, in a lesser extent to adenine was observed as judging from the difference Raman bands at 1315, 1354 and 1493 cm⁻¹. Copyright © 2013 John Wiley & Sons, Ltd.     

Applications of Raman spectroscopy in herbal medicine

Raman spectroscopic techniques are a group of chemical fingerprint detection methods based on molecular vibrational spectroscopy. They are compatible with aqueous solutions and are time saving, nondestructive, and highly informative. With complementary and alternative medicine (CAM) becoming increasingly popular, more people are consuming natural herbal medicines. Thus, chemical fingerprints of herbal medicines are investigated to determine the content of these products. In this study, I review the different types of Raman spectroscopic techniques used in fingerprinting herbal medicines, including dispersive Raman spectroscopy, resonance Raman spectroscopy, Fourier transform (FT)–Raman spectroscopy, surface-enhanced Raman scattering (SERS) spectroscopy, and confocal/microscopic Raman spectroscopy. Lab-grade Raman spectroscopy instruments help detect the chemical components of herbal medicines effectively and accurately without the need for complicated separation and extraction procedures. In addition, portable Raman spectroscopy instruments could be used to monitor the health and safety compliance of herbal products in the consumer market.     

The application of Raman and anti-stokes Raman spectroscopy for in situ monitoring of structural changes in laser irradiated titanium dioxide materials

The use of Raman and anti-stokes Raman spectroscopy to investigate the effect of exposure to high power laser radiation on the crystalline phases of TiO₂ has been investigated. Measurement of the changes, over several time integrals, in the Raman and anti-stokes Raman of TiO₂ spectra with exposure to laser radiation is reported. Raman and anti-stokes Raman provide detail on both the structure and the kinetic process of changes in crystalline phases in the titania material. The effect of laser exposure resulted in the generation of increasing amounts of the rutile crystalline phase from the anatase crystalline phase during exposure. The Raman spectra displayed bands at 144 cm⁻¹ (A1g), 197 cm⁻¹ (Eg), 398 cm⁻¹ (B1g), 515 cm⁻¹ (A1g), and 640 cm⁻¹ (Eg) assigned to anatase which were replaced by bands at 143 cm⁻¹ (B1g), 235 cm⁻¹ (2 phonon process), 448 cm⁻¹ (Eg) and 612 cm⁻¹ (A1g) which were assigned to rutile. This indicated that laser irradiation of TiO₂ changes the crystalline phase from anatase to rutile. Raman and anti-stokes Raman are highly sensitive to the crystalline forms of TiO₂ and allow characterisation of the effect of laser irradiation upon TiO₂. This technique would also be applicable as an in situ method for monitoring changes during the laser irradiation process.     

Recent Advances in linear and nonlinear Raman spectroscopy I

Raman spectroscopy has advanced considerably in the last several years due to rapid developments in instrumentation and the availability of theoretical methods for accurate calculation of Raman spectra, thus enormously facilitating the interpretation of Raman data. This review is restricted to cover papers mainly published in the Journal of Raman Spectroscopy, which serve to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2007 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy II

Following the first review on recent advances in linear and nonlinear Raman spectroscopy, the present review summarizes papers mainly published in the Journal of Raman Spectroscopy during 2007. This serves to give a fast overview of recent advances in this research field as well as to provide readers of this journal a quick introduction to the various subfields of Raman spectroscopy. It also reflects the current research interests of the Raman community. Similar reviews of highly active areas of Raman spectroscopy will appear in future issues of this journal. Copyright © 2008 John Wiley & Sons, Ltd.     

Application of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy to interrogate concealed biomaterials

In this paper, we demonstrate the ability of portable Raman spectroscopy and benchtop spatially offset Raman spectroscopy (SORS) techniques to rapidly identify real and fake ivory samples. Both techniques were able to identify exposed genuine from fake ivory samples. In contrast to conventional Raman spectroscopy, SORS was, in addition, able to identify ivory concealed by plastics, paints, varnishes and cloth. Application of the SORS technique allows the interrogation of biomaterial samples through materials in which conventional Raman spectroscopic instrumentation cannot penetrate. Copyright © 2009 John Wiley & Sons, Ltd.     

Structural properties of core and surface of silica nanoparticles investigated by Raman spectroscopy

We studied the experimental Raman spectra of various commercial silica nanoparticles of average diameter from 7 to 40 nm and specific surface from 50 to 380 m²/g. We found that the peculiarities of the particles Raman spectra systematically depend on their specific surface. In detail, the peak position of the R band at about 440 cm⁻¹ shifts towards high wavenumbers following an almost linear dependence on the specific surface. Similarly, the amplitudes of the D1 and D2 bands, at about 495 and 605 cm⁻¹, respectively, increase linearly with the same quantity. Our results are interpreted in the frame of the shell model for the nanoparticles clarifying that the network of the core of the nanoparticles is comparable to the bulk silica materials, whereas the surface shell has a ring statistic shifted to the low member rings and features an higher density. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterisation and classification of automotive clear coats with Raman spectroscopy and chemometrics for forensic purposes

The clear coats from a collection of automotive paint samples of 139 vehicles, covering a range of Australian and international vehicle manufacturers and sold in Western Australia, were characterised using FT‐Raman spectroscopy. Principal component analysis (PCA) revealed 19 distinct classes that were associated with the vehicles' manufacturer and model, and in the case of Australian manufacturers, the years of manufacture. Linear discriminant analysis based on the PCA groupings gave excellent discrimination between the groups with 96.9% of the calibration set and 97.6% of the validation set being correctly classified. Although the sample set comprised only vehicles available in Australia, the methodology used is universal and hence applicable in any jurisdiction that is willing and able to generate a statistically significant data set and maintain and update it as new vehicles appear on the market. A FT‐Raman spectroscopy‐based database would rapidly provide information regarding vehicle origin and manufacture and hence generate investigative leads for questioned paint samples found at incident sites. Copyright © 2016 John Wiley & Sons, Ltd.     

喇曼感生克尔效应光谱的琼斯矩阵分析

介绍喇曼感生克尔效应光谱(RIKES)的琼斯(Jones)矩阵分析方法.探测光束的传输强度不仅由所经过的每一个光学器件的琼斯矩阵所决定,而且还受到强的泵波在非线性介质样品中感生依赖于强度的二向色性和双折射(克尔效应)对琼斯矩阵的影响.同时计及样品和光学器件由强泵波作用下感生应力和其他外部产生的线双折射对喇曼感生克尔效应光谱观察的不利影响,导出测量系统的功率传输函数的完整表达式和喇曼感生克尔效应光谱的实现观察条件,最后简述以甲笨(C_7H_8)液体为试样的喇曼感生克尔效应光谱实验结果分析.     

Recent advances in linear and nonlinear Raman spectroscopy. Part VII

The aim of this paper is to provide an overview of advances in the field of Raman spectroscopy as reflected in articles published each year in the Journal of Raman Spectroscopy as well as in trends across related journals publishing in this research area. The context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the International Conference on Advanced Vibrational Spectroscopy in Kobe Japan in August 2013 and at SCIX 2013 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Milwaukee, Wisconsin, USA, October 2013. Papers published in the Journal of Raman Spectroscopy in 2012 are highlighted in this review and reflect topics and advances at the frontier of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level in an ever widening sphere of novel applications. Copyright © 2013 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy. Part IV

The purpose of the review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in the Journal of Raman Spectroscopy (JRS) as well as in trends across all related journals publishing in this research area. Context for the review is provided by considering statistical data on citations for the Thompson Reuters ISI Web of Science by year and by subfield of Raman spectroscopy. Additional statistics of number of papers and posters presented by category at the XXII International Conference on Raman Spectroscopy (ICORS 2010) is also provided. Papers published in JRS in 2009, as reviewed here, reflect trends at the cutting edge of Raman spectroscopy which is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever widening sphere of novel applications. Copyright © 2010 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy. Part V

The purpose of the review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in JRS as well as in trends across all related journals publishing in this research area. Context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the meetings of the Federation of Analytical Chemistry and Spectroscopy Societies 2011 and the Sixth International Conference on Advanced Vibrational Spectroscopy 2011. Papers published in JRS in 2010, as reviewed here, reflect trends at the cutting edge of Raman spectroscopy, which is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever‐widening sphere of novel applications. Copyright © 2011 John Wiley & Sons, Ltd.     

水下拉曼光谱探测低通滤光片水拉曼信号抑制

拉曼光谱作为研究物质结构的一个强有力工具,被广泛应用于水环境物质的检测,近年在深海原位探测中也得到应用.文章针对水下拉曼光谱探测的需要,设计了用于水的O-H振动拉曼信号抑制的低通滤光片,经过计算,边缘为指数形式的低通滤光片可较好的满足需要,而且通过实际采用的低通滤光片的实验证明,采用低通滤光片后水的O-H振动拉曼信号得...     

Passive signal enhancement in spatially offset Raman spectroscopy

We demonstrate experimentally, for the first time, the feasibility of enhancing signals in Spatially Offset Raman Spectroscopy (SORS) using a dielectric bandpass filter, building on our earlier experimental work on the enhancement of transmission Raman signals. The method is shown to lead to the enhancement of both the surface and subsurface Raman layer signal improving the signal‐to‐noise ratio of Raman spectra from the deep areas of samples, thus enhancing the technique's sensitivity and penetration depth. The filter is placed over the laser illumination zone, on the sample surface acting as a ‘unidirectional’ mirror transmitting the collimated laser beam on one side and reflecting photons escaping from the sample back into it. This enhances the degree of coupling of laser radiation into the medium and associated generated Raman signal. The feasibility study was performed on a two‐layer sample with the second layer located at the limit of the penetration depth of the method for this sample. The sample consisted of a 2.2‐mm over‐layer of a thinned paracetamol tablet followed by a 2‐mm layer of trans‐stilbene powder. The Raman signal was collected from a spatially offset region through a hole fabricated within the filter. The experiments demonstrate the presence of an enhancement of the Raman signal from both the layers by a factor of 4.4–4.5 and the improved signal‐to‐noise ratio of sublayer signal by a factor of 2.2, in agreement with photon shot noise dominated signal. Copyright © 2008 John Wiley & Sons, Ltd.     

Recent advances in linear and nonlinear Raman spectroscopy. Part VI

The purpose of this review is to provide a concise overview of recent advances in the broadly defined field of Raman spectroscopy as reflected in part by the many articles published each year in Journal of Raman Spectroscopy as well as in trends across all related journals publishing in this research area. Context for this review is derived from statistical data on article counts obtained from Thomson Reuters ISI Web of Knowledge by year and by subfield of Raman spectroscopy. Additional information is gleaned from presentations featuring Raman spectroscopy presented at the XXIII International Conference on Raman Spectroscopy in Bangalore, India, in August 2012 and at Scientific Exchange 2012 sponsored by the Federation of Analytical Chemistry and Spectroscopy Societies in Kansas City, Missouri, USA, October 2012. Papers published in the Journal of Raman Spectroscopy in 2011 are highlighted in this review and reflect trends at the cutting edge of Raman spectroscopy, a field that is expanding rapidly as a sensitive photonic probe of matter at the molecular level with an ever widening sphere of novel applications. Copyright © 2012 John Wiley & Sons, Ltd.     

Wide area Raman spectroscopy

Raman spectroscopy allows nondestructive analysis of materials using laser illumination. However, most Raman spectrometers can only provide good signal levels and sufficient spectral resolution, by focusing the laser to micrometer-sized spots. This equates to enormous laser intensities, which for samples with even very minor optical absorption either means destroying or damaging it by absorbing even a tiny fraction of the laser power, or it means reducing the laser intensity and hence the signal level. Furthermore, Raman signals generated above or below the focal plane are rejected in traditional Raman spectrometers. As signal levels are already extremely low in Raman spectroscopy, several schemes offer an alternative to focusing down to a diffraction-limited spot, to increase the area by up to 6 orders of magnitude, and increase the sampling depth. This review describes and compares these schemes, and estimates the typical illumination areas.     

Influence of dietary fibre on gluten proteins structure – a study on model flour with application of FT‐Raman spectroscopy

Dietary fibres are regarded as the source of polysaccharides and antioxidants such as polyphenols. However, addition of dietary fibre to bread causes significant reduction in its quality. The bread quality is connected with the structure of gluten proteins. For this reason, Fourier transform Raman spectroscopy was applied to determine changes in structure of gluten proteins modified by seven dietary fibres. The fibres were added to model flour reconstituted with wheat gluten and wheat starch. The model flour was used to provide gluten proteins of definite structure. The obtained results showed that six out of seven fibres caused similar changes in β‐turn structures. The appearance of the band at 1642 cm⁻¹ and the shift toward lower wavenumbers of the band at 1670 cm⁻¹ in the difference spectra indicated hydrogen bonding of carbonyl groups in β‐turns leading to protein folding/aggregation. Addition of fibre preparations caused also changes in conformation of disulfide bridges (S–S), corresponding to transformation to trans‐gauche‐gauche and trans‐gauche‐trans conformations at the expense of the stable gauche‐gauche‐gauche conformation. The S–S bonds in less stable conformations were formed inside the protein complex as well as between protein complexes in the form of β‐structures. Generally, the observed changes in gluten proteins after addition of dietary fibres were results of interactions between fibre polysaccharides and gluten proteins rather than between polyphenols and gluten proteins. Copyright © 2015 John Wiley & Sons, Ltd.     

凝聚态物质中的光声喇曼效应理论

用热弹性理论系统地分析了凝聚态物质的光声喇曼效应,分别导出了连续和脉冲激光泵浦下的光声喇曼信号表达式,并做了数值估算.     

Microbiological identification by surface-enhanced Raman spectroscopy

New methods for pathogens identification are of growing interest in clinical and food sectors. The challenge remains to develop rapid methods that are more simple, reliable, and specific. Surface-enhanced Raman spectroscopy (SERS) appears to be a promising tool to compete with current untargeted identification methods. This article presents the intensive research devoted to the use of SERS for bacterial identification, from the first to the very recent published results. Compared to normal Raman spectroscopy, the introduction of nanoparticles for SERS acquisition introduces a new degree of complexity. Bacterial Raman fingerprints, which are already subject to high spectral variability for a given strain, become then very dependent on numerous experimental parameters. To overcome these limitations, several approaches have been proposed to prepare the sample, from the microbiological culture conditions to the analysis of the spectrum including the coupling of nanoparticles on the bacterial membrane. Main strategies proposed over the last 20 years are examined here and discussed in the perspective of a protocol transfer towards industry.