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Sample records for raman spectroscopy applied

  1. Raman spectroscopy

    SciTech Connect

    Gerrard, D.L.; Bowley, H.J.

    1986-04-01

    The period of this review is from late 1983 to late 1985. During this time over 5000 papers have appeared in the scientific literature dealing with many applications of Raman spectroscopy and extending its use to several new areas of study. As in the previous review in this series most of the applications relevant to solids are covered in one or other of the ten categories, which are the same as those used previously. However, aspects relating to solids which are not covered elsewhere include general reviews and the specific field of semiconductors. This is an area of great current interest in terms of Raman spectroscopy and the characterization of semiconductor materials and surfaces has been reported. Raman scattering also provides a new probe for the elucidation of structural properties of microcrystalline silicon and resonance Raman scattering in silicon at elevated temperatures has been studied. Many studies on carbon have also appeared in the literature including that of the various types of carbon, the use of Raman scattering to investigate disorder and crystallite formation in annealed carbon, in situ studies of intercalation kinetics, structural aspects of cokes and coals, and instrumentation for coal gasification. Raman spectroscopy has been applied to such diverse systems as organic crystals, the determination of modifications in layered crystals, the detection of explosives on silica gel or carbon, diagnostics of heterogeneous chemical processes, and a study of tungsten-halogen bulbs. Laser Raman spectroscopy has also been coupled with liquid chromatography and phase-resolved background suppression has been used to enhance Raman spectra. 397 references.

  2. Surface-enhanced Raman spectroscopy applied to food safety.

    PubMed

    Craig, Ana Paula; Franca, Adriana S; Irudayaraj, Joseph

    2013-01-01

    Surface-enhanced Raman spectroscopy (SERS) is an advanced Raman technique that enhances the vibrational spectrum of molecules adsorbed on or in the vicinity of metal particles and/or surfaces. Because of its readiness, sensitivity, and minimum sample preparation requirements, SERS is being considered as a powerful technique for food inspection. Key aspects of food-safety assurance, spectroscopy methods, and SERS are briefly discussed in an extended introduction of this review. The recent and potential advances in SERS are highlighted in sections that deal with the (a) detection of food-borne pathogenic microorganisms and (b) the detection of food contaminants and adulteration, concentrated specifically on antibiotics, drugs, hormones, melamine, and pesticides. This review provides an outlook of the work done and a perspective on the future directions of SERS as a reliable tool for food-safety assessment. PMID:23297774

  3. Raman Spectroscopy.

    ERIC Educational Resources Information Center

    Gerrard, Donald L.

    1984-01-01

    Reviews literature on Raman spectroscopy from late 1981 to late 1983. Topic areas include: instrumentation and sampling; liquids and solutions; gases and matrix isolation; biological molecules; polymers; high-temperature and high-pressure studies; Raman microscopy; thin films and surfaces; resonance-enhanced and surface-enhanced spectroscopy; and…

  4. Raman Spectroscopy Applied to Mars Water Cycle Studies

    NASA Astrophysics Data System (ADS)

    Nikolakakos, G.; Whiteway, J. A.

    2014-12-01

    One of the key findings during the Phoenix and Mars Science Laboratory landed Mars missions has been the detection of perchlorate, a highly deliquescent salt. Perchlorates are of great interest on Mars due to their high affinity for water vapour as well as their ability to greatly depress the freezing point of water when in solution. This has intriguing biological implications as resulting brines could potentially provide a habitable environment for living organisms. Additionally, it has been speculated that these salts may play a significant role in influencing the hydrological cycle on Mars. In order to experimentally study brine formation on Mars and assess the feasibility of a future landed detection tool, a stand-off Raman spectroscopy instrument and environmental simulation chamber have been developed at York University. A sample of magnesium perchlorate has been subjected to the water vapour pressure, background pressure and temperatures found at polar Martian latitudes. Results indicate that at a water vapour pressure of ~20 Pa, Raman spectroscopy is able to detect the onset of brine formation and provide an estimate of the quantity of water taken up by the sample. At the lower water vapour pressures typically found on Mars ( ~1 Pa), it appears that slower dynamics inhibit the onset of water uptake over relevant time scales. The experimental setup and current results will be presented.

  5. Raman spectroscopy

    SciTech Connect

    Gerrard, D.L.; Bowley, H.J.

    1988-06-15

    The period of this review is from late 1985 to late 1987. During this time over 6000 papers have been published in the scientific literature dealing with many applications of Raman spectroscopy and extending its use to new areas of study. This article covers only those papers that are relevant to the analytical chemist and this necessitates a highly selective approach. There are some areas that have been the subject of many papers with relatively few being of analytical interest. In such cases the reader is referred to appropriate reviews which are detailed in this section.

  6. Raman spectroscopy and capillary electrophoresis applied to forensic colour inkjet printer inks analysis.

    PubMed

    Król, Małgorzata; Karoly, Agnes; Kościelniak, Paweł

    2014-09-01

    Forensic laboratories are increasingly engaged in the examination of fraudulent documents, and what is important, in many cases these are inkjet-printed documents. That is why systematic approaches to inkjet printer inks comparison and identification have been carried out by both non-destructive and destructive methods. In this study, micro-Raman spectroscopy and capillary electrophoresis (CE) were applied to the analysis of colour inkjet printer inks. Micro-Raman spectroscopy was used to study the chemical composition of colour inks in situ on a paper surface. It helps to characterize and differentiate inkjet inks, and can be used to create a spectra database of inks taken from different cartridge brands and cartridge numbers. Capillary electrophoresis in micellar electrophoretic capillary chromatography mode was applied to separate colour and colourless components of inks, enabling group identification of those components which occur in a sufficient concentration (giving intensive peaks). Finally, on the basis of the obtained results, differentiation of the analysed inks was performed. Twenty-three samples of inkjet printer inks were examined and the discriminating power (DP) values for both presented methods were established in the routine work of experts during the result interpretation step. DP was found to be 94.0% (Raman) and 95.6% (CE) when all the analysed ink samples were taken into account, and it was 96.7% (Raman) and 98.4% (CE), when only cartridges with different index numbers were considered. PMID:25062531

  7. Raman spectroscopy of composites

    SciTech Connect

    Young, R.J.; Andrews, M.C.; Yang, X.; Huang, Y.L.; Gu, X.; Day, R.J.

    1994-12-31

    It is demonstrated that Raman Spectroscopy can be used to follow the micromechanics of the deformation of high-performance fibers within composites. The technique can be applied to a wide range of fiber systems including aramids, carbon and ceramic (using fluorescence spectroscopy) fibers. Well-defined Raman spectra are obtained and the position of the Raman bands shift on the application of stress or strain. It is possible to determine the point-to-point variation of strain along an individual fiber inside a transparent matrix under any general state of stress or strain. Examples are given of the use of the technique to study a variety of phenomena in a wide range of composite systems. The phenomena investigated include thermal stresses, fiber/matrix adhesion, matrix yielding for both fragmentation and pull-out tests. The systems studied include aramid/epoxy, carbon/epoxy and ceramic-fiber/glass composites.

  8. In vivo Raman spectroscopy detects increased epidermal antioxidative potential with topically applied carotenoids

    NASA Astrophysics Data System (ADS)

    Lademann, J.; Caspers, P. J.; van der Pol, A.; Richter, H.; Patzelt, A.; Zastrow, L.; Darvin, M.; Sterry, W.; Fluhr, J. W.

    2009-01-01

    In the present study, the distribution of the carotenoids as a marker for the complete antioxidative potential in human skin was investigated before and after the topical application of carotenoids by in vivo Raman spectroscopy with an excitation wavelength of 785 nm. The carotenoid profile was assessed after a short term topical application in 4 healthy volunteers. In the untreated skin, the highest concentration of natural carotenoids was detected in different layers of the stratum corneum (SC) close to the skin surface. After topical application of carotenoids, an increase in the antioxidative potential in the skin could be observed. Topically applied carotenoids penetrate deep into the epidermis down to approximately 24 μm. This study supports the hypothesis that antioxidative substances are secreted via eccrine sweat glands and/or sebaceous glands to the skin surface. Subsequently they penetrate into the different layers of the SC.

  9. Solid state characterization of chloramphenicol palmitate. Raman spectroscopy applied to pharmaceutical polymorphs

    NASA Astrophysics Data System (ADS)

    Gamberini, M. C.; Baraldi, C.; Tinti, A.; Rustichelli, C.; Ferioli, V.; Gamberini, G.

    2006-03-01

    A pharmaceutical active compound, chloramphenicol palmitate, appears in three polymorphic forms, that can be observed at room temperature. The stable form A (biologically inactive modification), the meta-stable form B (active modification) and unstable form C were found to have distinct Raman spectra, with bands attributable to the different polymorphs. The use of hot-stage Raman microscopy (the direct coupling of Raman microscopy and hot-stage) is demonstrated for the drug substance chloramphenicol palmitate form C. All modifications of form C were produced and identified by hot-stage Raman microscopy. A close correlation of thermal and spectroscopic information was achieved by this combination of techniques. As reported in several pharmacopoeias, the content of form A should be less than 10%; therefore, a mixture of 10% (w/w) A in B was prepared, and the presence of the characteristic bands of form A after subtraction of the pure B was revealed. Moreover, mixtures between 2 and 12% (w/w) A in B were investigated and the intensity ratio (as peak area) I 413-435/I 1035-1158 as a function of A percentage has been demonstrated to show a linear trend. Other methods for the characterization of polymorphs were used: Fourier transform infrared spectroscopy (FT-IR), Diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), Differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD).

  10. FTIR and Raman Spectroscopy Applied to Dementia Diagnosis Through Analysis of Biological Fluids.

    PubMed

    Lopes, Jéssica; Correia, Marta; Martins, Ilka; Henriques, Ana Gabriela; Delgadillo, Ivonne; da Cruz E Silva, Odete; Nunes, Alexandra

    2016-04-01

    To date, it is still difficult to perform an early and accurate diagnosis of dementia, therefore significant research has focused on finding new dementia biomarkers that can aid in this respect. There is an urgent need for non-invasive, rapid, and relatively inexpensive procedures for early diagnostics. Studies have demonstrated that of spectroscopic techniques, such as Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy could be a useful and accurate procedure to diagnose dementia. Given that several biochemical mechanisms related to neurodegeneration and dementia can lead to changes in plasma components and others peripheral body fluids; blood-based samples coupled to spectroscopic analyses can be used as a simple and less invasive approach. PMID:27079713

  11. Auger resonant Raman spectroscopy

    SciTech Connect

    Azuma, Y.; LeBrun, T.; MacDonald, M.; Southworth, S.H.

    1995-08-01

    As noted above, traditional spectroscopy of the electronic structure of the inner shells of atoms, molecules, and solids is limited by the lifetime broadening of the core-excited states. This limitation can also be avoided with the non-radiative analog of X-ray Raman scattering - resonant Auger Raman spectroscopy. We have used this technique to study the K-shell excitation spectrum of argon as the photon energy is continuously scanned across threshold.

  12. Femtosecond Stimulated Raman Spectroscopy.

    PubMed

    Dietze, Daniel R; Mathies, Richard A

    2016-05-01

    Femtosecond stimulated Raman spectroscopy (FSRS) is an ultrafast nonlinear optical technique that provides vibrational structural information with high temporal (sub-50 fs) precision and high spectral (10 cm(-1) ) resolution. Since the first full demonstration of its capabilities ≈15 years ago, FSRS has evolved into a mature technique, giving deep insights into chemical and biochemical reaction dynamics that would be inaccessible with any other technique. It is now being routinely applied to virtually all possible photochemical reactions and systems spanning from single molecules in solution to thin films, bulk crystals and macromolecular proteins. This review starts with an historic overview and discusses the theoretical and experimental concepts behind this technology. Emphasis is put on the current state-of-the-art experimental realization and several variations of FSRS that have been developed. The unique capabilities of FSRS are illustrated through a comprehensive presentation of experiments to date followed by prospects. PMID:26919612

  13. Surface-Enhanced Raman Spectroscopy.

    ERIC Educational Resources Information Center

    Garrell, Robin L.

    1989-01-01

    Reviews the basis for the technique and its experimental requirements. Describes a few examples of the analytical problems to which surface-enhanced Raman spectroscopy (SERS) has been and can be applied. Provides a perspective on the current limitations and frontiers in developing SERS as an analytical technique. (MVL)

  14. Raman spectroscopy in astrobiology.

    PubMed

    Jorge Villar, Susana E; Edwards, Howell G M

    2006-01-01

    Raman spectroscopy is proposed as a valuable analytical technique for planetary exploration because it is sensitive to organic and inorganic compounds and able to unambiguously identify key spectral markers in a mixture of biological and geological components; furthermore, sample manipulation is not required and any size of sample can be studied without chemical or mechanical pretreatment. NASA and ESA are considering the adoption of miniaturised Raman spectrometers for inclusion in suites of analytical instrumentation to be placed on robotic landers on Mars in the near future to search for extinct or extant life signals. In this paper we review the advantages and limitations of Raman spectroscopy for the analysis of complex specimens with relevance to the detection of bio- and geomarkers in extremophilic organisms which are considered to be terrestrial analogues of possible extraterrestial life that could have developed on planetary surfaces. PMID:16456933

  15. Fiber enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Frosch, T.; Yan, D.; Hanf, S.; Popp, J.

    2014-05-01

    Fiber enhanced Raman sensing is presented for versatile and extremely sensitive analysis of pharmaceutical drugs and biogenic gases. Elaborated micro-structured optical fibers guide the light with very low losses within their hollow core and provide at the same time a miniaturized sample container for the analytes. Thus, fiber enhanced Raman spectroscopy (FERS) allows for chemically selective detection of minimal sample amounts with high sensitivity. Two examples are presented in this contribution: (i) the detection of picomolar concentrations of pharmaceutical drugs; and (ii) the analysis of biogenic gases within a complex mixture of gases with analytical sensitivities in the ppm range.

  16. A new high-resolution, high-throughput spectrometer: first experience as applied to Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Meade, Jeffrey T.; Behr, Bradford B.; Hajian, Arsen R.

    2012-06-01

    The classic trade-off between resolution and throughput in a dispersive spectrometer is overcome using virtual slit technology. An optimized spectrometer designed from the ground up to incorporate a virtual slit is experimentally demonstrated by Raman experiments.

  17. Scanning angle Raman spectroscopy: Investigation of Raman scatter enhancement techniques for chemical analysis

    SciTech Connect

    Meyer, Matthew W.

    2013-01-01

    This thesis outlines advancements in Raman scatter enhancement techniques by applying evanescent fields, standing-waves (waveguides) and surface enhancements to increase the generated mean square electric field, which is directly related to the intensity of Raman scattering. These techniques are accomplished by employing scanning angle Raman spectroscopy and surface enhanced Raman spectroscopy. A 1064 nm multichannel Raman spectrometer is discussed for chemical analysis of lignin. Extending dispersive multichannel Raman spectroscopy to 1064 nm reduces the fluorescence interference that can mask the weaker Raman scattering. Overall, these techniques help address the major obstacles in Raman spectroscopy for chemical analysis, which include the inherently weak Raman cross section and susceptibility to fluorescence interference.

  18. Applications of Raman spectroscopy in life science

    NASA Astrophysics Data System (ADS)

    Martin, Airton A.; T. Soto, Cláudio A.; Ali, Syed M.; Neto, Lázaro P. M.; Canevari, Renata A.; Pereira, Liliane; Fávero, Priscila P.

    2015-06-01

    Raman spectroscopy has been applied to the analysis of biological samples for the last 12 years providing detection of changes occurring at the molecular level during the pathological transformation of the tissue. The potential use of this technology in cancer diagnosis has shown encouraging results for the in vivo, real-time and minimally invasive diagnosis. Confocal Raman technics has also been successfully applied in the analysis of skin aging process providing new insights in this field. In this paper it is presented the latest biomedical applications of Raman spectroscopy in our laboratory. It is shown that Raman spectroscopy (RS) has been used for biochemical and molecular characterization of thyroid tissue by micro-Raman spectroscopy and gene expression analysis. This study aimed to improve the discrimination between different thyroid pathologies by Raman analysis. A total of 35 thyroid tissues samples including normal tissue (n=10), goiter (n=10), papillary (n=10) and follicular carcinomas (n=5) were analyzed. The confocal Raman spectroscopy allowed a maximum discrimination of 91.1% between normal and tumor tissues, 84.8% between benign and malignant pathologies and 84.6% among carcinomas analyzed. It will be also report the application of in vivo confocal Raman spectroscopy as an important sensor for detecting advanced glycation products (AGEs) on human skin.

  19. Fast label-free detection of Legionella spp. in biofilms by applying immunomagnetic beads and Raman spectroscopy.

    PubMed

    Kusić, Dragana; Rösch, Petra; Popp, Jürgen

    2016-03-01

    Legionellae colonize biofilms, can form a biofilm by itself and multiply intracellularly within the protozoa commonly found in water distribution systems. Approximately half of the known species are pathogenic and have been connected to severe multisystem Legionnaires' disease. The detection methods for Legionella spp. in water samples are still based on cultivation, which is time consuming due to the slow growth of this bacterium. Here, we developed a cultivation-independent, label-free and fast detection method for legionellae in a biofilm matrix based on the Raman spectroscopic analysis of isolated single cells via immunomagnetic separation (IMS). A database comprising the Raman spectra of single bacterial cells captured and separated from the biofilms formed by each species was used to build the identification method based on a support vector machine (SVM) discriminative classifier. The complete method allows the detection of Legionella spp. in 100 min. Cross-reactivity of Legionella spp. specific immunomagnetic beads to the other studied genera was tested, where only small cell amounts of Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli compared to the initial number of cells were isolated by the immunobeads. Nevertheless, the Raman spectra collected from isolated non-targeted bacteria were well-discriminated from the Raman spectra collected from isolated Legionella cells, whereby the Raman spectra of the independent dataset of Legionella strains were assigned with an accuracy of 98.6%. In addition, Raman spectroscopy was also used to differentiate between isolated Legionella species. PMID:26915495

  20. Transcutaneous Raman Spectroscopy of Bone

    NASA Astrophysics Data System (ADS)

    Maher, Jason R.

    Clinical diagnoses of bone health and fracture risk typically rely upon measurements of bone density or structure, but the strength of a bone is also dependent upon its chemical composition. One technology that has been used extensively in ex vivo, exposed-bone studies to measure the chemical composition of bone is Raman spectroscopy. This spectroscopic technique provides chemical information about a sample by probing its molecular vibrations. In the case of bone tissue, Raman spectra provide chemical information about both the inorganic mineral and organic matrix components, which each contribute to bone strength. To explore the relationship between bone strength and chemical composition, our laboratory has contributed to ex vivo, exposed-bone animal studies of rheumatoid arthritis, glucocorticoid-induced osteoporosis, and prolonged lead exposure. All of these studies suggest that Raman-based predictions of biomechanical strength may be more accurate than those produced by the clinically-used parameter of bone mineral density. The utility of Raman spectroscopy in ex vivo, exposed-bone studies has inspired attempts to perform bone spectroscopy transcutaneously. Although the results are promising, further advancements are necessary to make non-invasive, in vivo measurements of bone that are of sufficient quality to generate accurate predictions of fracture risk. In order to separate the signals from bone and soft tissue that contribute to a transcutaneous measurement, we developed an overconstrained extraction algorithm that is based upon fitting with spectral libraries derived from separately-acquired measurements of the underlying tissue components. This approach allows for accurate spectral unmixing despite the fact that similar chemical components (e.g., type I collagen) are present in both soft tissue and bone and was applied to experimental data in order to transcutaneously detect, to our knowledge for the first time, age- and disease-related spectral

  1. Raman Spectroscopy of Cocrystals

    NASA Astrophysics Data System (ADS)

    Rooney, Frank; Reardon, Paul; Ochoa, Romulo; Abourahma, Heba; Marti, Marcus; Dimeo, Rachel

    2010-02-01

    Cocrystals are a class of compounds that consist of two or more molecules that are held together by hydrogen bonding. Pharmaceutical cocrystals are those that contain an active pharmaceutical ingredient (API) as one of the components. Pharmaceutical cocrystals are of particular interest and have gained a lot of attention in recent years because they offer the ability to modify the physical properties of the API, like solubility and bioavailability, without altering the chemical structure of the API. The APIs that we targeted for our studies are theophylline (Tp) and indomethacin (Ind). These compounds have been mixed with complementary coformers (cocrystal former) that include acetamide (AcONH2), melamine (MLM), nicotinic acid (Nic-COOH), 4-cyanopyridine (4-CNPy) and 4-aminopyridine (4-NH2Py). Raman spectroscopy has been used to characterize these cocrystals. Spectra of the cocrystals were compared to those of the coformers to analyze for peak shifts, specifically those corresponding to hydrogen bonding. A 0.5 m CCD Spex spectrometer was used, in a micro-Raman setup, for spectral analysis. An Argon ion Coherent laser at 514.5 nm was used as the excitation source. )

  2. Online fluorescence suppression in modulated Raman spectroscopy.

    PubMed

    De Luca, Anna Chiara; Mazilu, Michael; Riches, Andrew; Herrington, C Simon; Dholakia, Kishan

    2010-01-15

    Label-free chemical characterization of single cells is an important aim for biomedical research. Standard Raman spectroscopy provides intrinsic biochemical markers for noninvasive analysis of biological samples but is often hindered by the presence of fluorescence background. In this paper, we present an innovative modulated Raman spectroscopy technique to filter out the Raman spectra from the fluorescence background. The method is based on the principle that the fluorescence background does not change whereas the Raman scattering is shifted by the periodical modulation of the laser wavelength. Exploiting this physical property and importantly the multichannel lock-in detection of the Raman signal, the modulation technique fulfills the requirements of an effective fluorescence subtraction method. Indeed, once the synchronization and calibration procedure is performed, minimal user intervention is required, making the method online and less time-consuming than the other fluorescent suppression methods. We analyze the modulated Raman signal and shifted excitation Raman difference spectroscopy (SERDS) signal of 2 mum-sized polystyrene beads suspended in a solution of fluorescent dye as a function of modulation rate. We show that the signal-to-noise ratio of the modulated Raman spectra at the highest modulation rate is 3 times higher than the SERDS one. To finally evaluate the real benefits of the modulated Raman spectroscopy, we apply our technique to Chinese hamster ovary cells (CHO). Specifically, by analyzing separate spectra from the membrane, cytoplasm, and nucleus of CHO cells, we demonstrate the ability of this method to obtain localized sensitive chemical information from cells, away from the interfering fluorescence background. In particular, statistical analysis of the Raman data and classification using PCA (principal component analysis) indicate that our method allows us to distinguish between different cell locations with higher sensitivity and

  3. NanoSIMS and Micro-Raman Spectroscopy applied to the Analysis of Uranium Oxyfluoride Particles for Nuclear Safeguards

    NASA Astrophysics Data System (ADS)

    Kips, R.; Kristo, M.; Crowhurst, J.; Stefaniak, E.; Hutcheon, I. D.

    2010-12-01

    Environmental swipe sampling is used by safeguards organizations to verify the absence of undeclared nuclear activities. Particulate material collected in environmental swipe samples is typically analyzed for its uranium isotopic composition. At enrichment facilities, these swipe samples often contain UO2F2 particles formed from the hydrolysis of uranium hexafluoride gas. Since UO2F2 particulate material has been found to be unstable with respect to the loss of fluorine (J.A. Carter et al. Task A.200.3 K/NSP-777, 1998) the measurement of the residual amount of fluorine has the potential of placing boundaries on the particle’s age and exposure history. To investigate the decomposition of UO2F2 and its potential applications in nuclear safeguards and nuclear forensics, a suite of micro-analytical tools was applied to a set of lab-synthesized UO2F2 particles. Samples were either stored in an inert atmosphere or exposed to different levels of humidity, temperature and light to identify those environmental conditions that accelerate the decomposition of UO2F2. Given the small size of the particles, secondary ion mass spectrometry with nanometer-scale spatial resolution (NanoSIMS) was used to measure the relative amount of fluorine. The elemental data from the NanoSIMS was complemented with micro-Raman spectroscopy for molecular fingerprinting. These measurements showed that even though the decomposition of UO2F2 generally happens very slowly, subtle differences can be distinguished depending on the environmental conditions to which they were exposed. The exposure to humidity was identified as the main factor accelerating the loss of fluorine in UO2F2 particles. Particles exposed to 30 % relative humidity and higher showed a decrease in the relative amount of fluorine and a shift of the UO22+ symmetric stretching frequency towards lower frequencies. These changes were attributed to an increase in hydration of the UO2F2 particles. This work was performed under the

  4. Raman spectroscopy in halophile research

    PubMed Central

    Jehlička, Jan; Oren, Aharon

    2013-01-01

    Raman spectroscopy plays a major role in robust detection of biomolecules and mineral signatures in halophile research. An overview of Raman spectroscopic investigations in halophile research of the last decade is given here to show advantages of the approach, progress made as well as limits of the technique. Raman spectroscopy is an excellent tool to monitor and identify microbial pigments and other biomolecules in extant and extinct halophile biomass. Studies of bottom gypsum crusts from salterns, native evaporitic sediments, halite inclusions, and endoliths as well as cultures of halophilic microorganisms permitted to understand the content, distribution, and behavior of important molecular species. The first papers describing Raman spectroscopic detection of microbiological and geochemical key markers using portable instruments are highlighted as well. PMID:24339823

  5. Raman spectroscopy in halophile research.

    PubMed

    Jehlička, Jan; Oren, Aharon

    2013-01-01

    Raman spectroscopy plays a major role in robust detection of biomolecules and mineral signatures in halophile research. An overview of Raman spectroscopic investigations in halophile research of the last decade is given here to show advantages of the approach, progress made as well as limits of the technique. Raman spectroscopy is an excellent tool to monitor and identify microbial pigments and other biomolecules in extant and extinct halophile biomass. Studies of bottom gypsum crusts from salterns, native evaporitic sediments, halite inclusions, and endoliths as well as cultures of halophilic microorganisms permitted to understand the content, distribution, and behavior of important molecular species. The first papers describing Raman spectroscopic detection of microbiological and geochemical key markers using portable instruments are highlighted as well. PMID:24339823

  6. Raman spectroscopy of shocked water

    SciTech Connect

    Holmes, N.C.; Mitchell, A.C.; Nellis, W.J.; Graham, W.B.; Walrafen, G.E.

    1983-07-01

    Raman scattering has been used extensively to study the vibrational and rotational properties of molecules under a variety of conditions. Here, interest is in the behavior of water molecules shocked to high pressures and temperatures. Behind the shock front the water molecules undergo changes in bonding and the molecules may become ionized. Raman spectroscopy can be used to determine the molecular species behind the shock front. In addition, changes in Raman spectra can yield information regarding inter- and intramolecular potentials and the temperature behind the shock front.

  7. Raman Spectroscopy of Microbial Pigments

    PubMed Central

    Edwards, Howell G. M.; Oren, Aharon

    2014-01-01

    Raman spectroscopy is a rapid nondestructive technique providing spectroscopic and structural information on both organic and inorganic molecular compounds. Extensive applications for the method in the characterization of pigments have been found. Due to the high sensitivity of Raman spectroscopy for the detection of chlorophylls, carotenoids, scytonemin, and a range of other pigments found in the microbial world, it is an excellent technique to monitor the presence of such pigments, both in pure cultures and in environmental samples. Miniaturized portable handheld instruments are available; these instruments can be used to detect pigments in microbiological samples of different types and origins under field conditions. PMID:24682303

  8. Applications of Raman Spectroscopy to Virology and Microbial Analysis

    NASA Astrophysics Data System (ADS)

    Harz, Michaela; Stöckel, Stephan; Ciobotă, Valerian; Cialla, Dana; Rösch, Petra; Popp, Jürgen

    This chapter reports from the utilization of Raman spectroscopic techniques like Raman microscopy, Raman optical activity (ROA), UV-resonance Raman (UVRR)-spectroscopy, surface enhanced Raman spectroscopy (SERS), and tip-enhanced Raman spectroscopy (TERS) for the investigation of viruses and microorganisms, especially bacteria and yeasts for medical and pharmaceutical applications. The application of these Raman techniques allows for the analysis of chemical components of cells and subcellular regions, as well as the monitoring of chemical differences occurring as a result of the growth of microorganisms. In addition, the interaction of microorganisms with active pharmaceutical agents can be investigated. In combination with chemometric methods Raman spectroscopy can also be applied to identify microorganisms both in micro colonies and even on single cells.

  9. Raman Spectroscopy of Amorphous Carbon

    SciTech Connect

    Tallant, D.R.; Friedmann, T.A.; Missert, N.A.; Siegal, M.P.; Sullivan, J.P.

    1998-01-01

    Amorphous carbon is an elemental form of carbon with low hydrogen content, which may be deposited in thin films by the impact of high energy carbon atoms or ions. It is structurally distinct from the more well-known elemental forms of carbon, diamond and graphite. It is distinct in physical and chemical properties from the material known as diamond-like carbon, a form which is also amorphous but which has a higher hydrogen content, typically near 40 atomic percent. Amorphous carbon also has distinctive Raman spectra, whose patterns depend, through resonance enhancement effects, not only on deposition conditions but also on the wavelength selected for Raman excitation. This paper provides an overview of the Raman spectroscopy of amorphous carbon and describes how Raman spectral patterns correlate to film deposition conditions, physical properties and molecular level structure.

  10. Chemical analysis of acoustically levitated drops by Raman spectroscopy.

    PubMed

    Tuckermann, Rudolf; Puskar, Ljiljana; Zavabeti, Mahta; Sekine, Ryo; McNaughton, Don

    2009-07-01

    An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid-base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension. PMID:19418043

  11. Raman spectroscopy of illicit substances

    NASA Astrophysics Data System (ADS)

    Stokes, Robert J.; Faulds, Karen; Smith, W. Ewen

    2007-10-01

    Raman spectroscopy provides a very effective method of identifying an illicit substance in situ without separation or contact other than with a laser beam. The equipment required is steadily improving and is now reliable and simple to operate. Costs are also coming down and hand held portable spectrometers are proving very effective. The main limitations on the use of the technique are that it is insensitive in terms of the number of incident photons converted into Raman scattered photons and fluorescence produced in the sample by the incident radiation interferes. Newer methods, still largely in the development phase, will increase the potential for selected applications. The use of picosecond pulsed lasers can discriminate between fluorescence and Raman scattering and this has been used in the laboratory to examine street samples of illicit drugs. Surface-enhanced Raman scattering, in which the analyte requires to be adsorbed onto a roughened metal surface, creates a sensitivity to compete with fluorescence and quenches fluorescence for molecules on a surface. This provides the ability to detect trace amounts of substances in some cases. The improving optics, detection capability and the reliability of the new methods indicate that the potential for the use of Raman spectroscopy for security purposes will increase with time.

  12. Gradient temperature Raman spectroscopy identifies flexible sites in proline and alanine peptides

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Continuous thermo dynamic Raman spectroscopy (TDRS) applies the temperature gradients utilized in differential scanning calorimetry (DSC) to Raman spectroscopy, providing a straightforward technique to identify molecular rearrangements that occur just prior to phase transitions. Herein we apply TDRS...

  13. Raman spectroscopy of bone metastasis

    NASA Astrophysics Data System (ADS)

    Esmonde-White, Karen A.; Sottnik, Joseph; Morris, Michael; Keller, Evan

    2012-02-01

    Raman spectroscopy of bone has been used to characterize chemical changes occurring in diseases such as osteoporosis, osteoarthritis and osteomyelitis. Metastasis of cancer into bone causes changes to bone quality that are similar to those observed in osteoporosis, such as decreased bone strength, but with an accelerated timeframe. In particular, osteolytic (bone degrading) lesions in bone metastasis have a marked effect on patient quality of life because of increased risk of fractures, pain, and hypercalcemia. We use Raman spectroscopy to examine bone from two different mouse models of osteolytic bone metastasis. Raman spectroscopy measures physicochemical information which cannot be obtained through standard biochemical and histological measurements. This study was reviewed and approved by the University of Michigan University Committee on the Care and Use of Animals. Two mouse models of prostate cancer bone metastasis, RM1 (n=3) and PC3-luc (n=4) were examined. Tibiae were injected with RM1 or PC3-luc cancer cells, while the contralateral tibiae received a placebo injection for use as controls. After 2 weeks of incubation, the mice were sacrificed and the tibiae were examined by Raman microspectroscopy (λ=785 nm). Spectroscopic markers corresponding to mineral stoichiometry, bone mineralization, and mineral crystallinity were compared in spectra from the cancerous and control tibiae. X-ray imaging of the tibia confirmed extensive osteolysis in the RM1 mice, with tumor invasion into adjoining soft tissue and moderate osteolysis in the PC3-luc mice. Raman spectroscopic markers indicate that osteolytic lesions are less mineralized than normal bone tissue, with an altered mineral stoichiometry and crystallinity.

  14. FT-Raman Spectroscopy: A Catalyst for the Raman Explosion?

    ERIC Educational Resources Information Center

    Chase, Bruce

    2007-01-01

    The limitations of Fourier transform (FT) Raman spectroscopy, which is used to detect and analyze the scattered radiation, are discussed. FT-Raman has served to revitalize a field that was lagging and the presence of Raman instrumentation as a routine analytical tool is established for the foreseeable future.

  15. Raman Spectroscopy of Ocular Tissue

    NASA Astrophysics Data System (ADS)

    Ermakov, Igor V.; Sharifzadeh, Mohsen; Gellermann, Warner

    The optically transparent nature of the human eye has motivated numerous Raman studies aimed at the non-invasive optical probing of ocular tissue components critical to healthy vision. Investigations include the qualitative and quantitative detection of tissue-specific molecular constituents, compositional changes occurring with development of ocular pathology, and the detection and tracking of ocular drugs and nutritional supplements. Motivated by a better understanding of the molecular mechanisms leading to cataract formation in the aging human lens, a great deal of work has centered on the Raman detection of proteins and water content in the lens. Several protein groups and the hydroxyl response are readily detectable. Changes of protein compositions can be studied in excised noncataractous tissue versus aged tissue preparations as well as in tissue samples with artificially induced cataracts. Most of these studies are carried out in vitro using suitable animal models and conventional Raman techniques. Tissue water content plays an important role in optimum light transmission of the outermost transparent ocular structure, the cornea. Using confocal Raman spectroscopy techniques, it has been possible to non-invasively measure the water to protein ratio as a measure of hydration status and to track drug-induced changes of the hydration levels in the rabbit cornea at various depths. The aqueous humor, normally supplying nutrients to cornea and lens, has an advantageous anterior location for Raman studies. Increasing efforts are pursued to non-invasively detect the presence of glucose and therapeutic concentrations of antibiotic drugs in this medium. In retinal tissue, Raman spectroscopy proves to be an important tool for research into the causes of macular degeneration, the leading cause of irreversible vision disorders and blindness in the elderly. It has been possible to detect the spectral features of advanced glycation and advanced lipooxydation end products in

  16. Raman and Photoluminescence Spectroscopy in Mineral Identification

    NASA Astrophysics Data System (ADS)

    Kuehn, J. W.

    2014-06-01

    Raman spectroscopy is particularly useful for rapid identification of minerals and gemstones. Raman spectrometers also allow PL studies for authentication of samples and geological provenance, diamond type screening and detection of HPHT treatments.

  17. Characterization of Kevlar Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

    2007-01-01

    This paper explores the characterization of Kevlar composite materials using Raman spectroscopy. The goal of the research is to develop and understand the Raman spectrum of Kevlar materials to provide a foundation for the development of nondestructive evaluation (NDE) technologies based on the interaction of laser light with the polymer Kevlar. The paper discusses the fundamental aspects of experimental characterization of the spectrum of Kevlar, including the effects of incident wavelength, polarization and laser power. The effects of environmental exposure of Kevlar materials on certain characteristics of its Raman spectrum are explored, as well as the effects of applied stress. This data may provide a foundation for the development of NDE technologies intended to detect the in-situ deterioration of Kevlar materials used for engineering applications that can later be extended to other materials such as carbon fiber composites.

  18. Raman spectroscopy of triolein under high pressures

    NASA Astrophysics Data System (ADS)

    Tefelski, D. B.; Jastrzębski, C.; Wierzbicki, M.; Siegoczyński, R. M.; Rostocki, A. J.; Wieja, K.; Kościesza, R.

    2010-03-01

    This article presents results of the high pressure Raman spectroscopy of triolein. Triolein, a triacylglyceride (TAG) of oleic acid, is an unsaturated fat, present in natural oils such as olive oil. As a basic food component and an energy storage molecule, it has considerable importance for food and fuel industries. To generate pressure in the experiment, we used a high-pressure cylindrical chamber with sapphire windows, presented in (R.M. Siegoczyński, R. Kościesza, D.B. Tefelski, and A. Kos, Molecular collapse - modification of the liquid structure induced by pressure in oleic acid, High Press. Res. 29 (2009), pp. 61-66). Pressure up to 750 MPa was applied. A Raman spectrometer in "macro"-configuration was employed. Raman spectroscopy provides information on changes of vibrational modes related to structural changes of triolein under pressure. Interesting changes in the triglyceride C‒H stretching region at 2650-3100 cm-1 were observed under high-pressures. Changes were also observed in the ester carbonyl (C˭ O) stretching region 1700-1780 cm-1 and the C‒C stretching region at 1050-1150 cm-1. The overall luminescence of the sample decreased under pressure, making it possible to set longer spectrum acquisition time and obtain more details of the spectrum. The registered changes suggest that the high-pressure solid phase of triolein is organized as β-polymorphic, as was reported in (C. Akita, T. Kawaguchi, and F. Kaneko, Structural study on polymorphism of cis-unsaturated triacylglycerol: Triolein, J. Phys. Chem. B 110 (2006), pp. 4346-4353; E. Da Silva and D. Rousseau, Molecular order and thermodynamics of the solid-liquid transition in triglycerides via Raman spectroscopy, Phys. Chem. Chem. Phys. 10 (2008), pp. 4606-4613) (with temperature-induced phase transitions). The research has shown that Raman spectroscopy in TAGs under pressure reveals useful information about its structural changes.

  19. Raman spectroscopies in shock-compressed materials

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.; Shaner, J.W.

    1983-01-01

    Spontaneous Raman spectroscopy, stimulated Raman scattering and coherent anti-Stokes Raman scattering have been used to measure temperatures and changes in molecular vibrational frequencies for detonating and shocked materials. Inverse Raman and Raman induced Kerr effect spectroscopies have been suggested as diagnostic probes for determining and phenomenology of shock-induced chemical reactions. The practicality, advantages, and disadvantages of using Raman scattering techniques as diagnostic probes of microscopic phenomenology through and immediately behind the shock front of shock-compressed molecular systems are discussed.

  20. Raman Spectroscopy of Optically Trapped Single Biological Micro-Particles

    PubMed Central

    Redding, Brandon; Schwab, Mark J.; Pan, Yong-le

    2015-01-01

    The combination of optical trapping with Raman spectroscopy provides a powerful method for the study, characterization, and identification of biological micro-particles. In essence, optical trapping helps to overcome the limitation imposed by the relative inefficiency of the Raman scattering process. This allows Raman spectroscopy to be applied to individual biological particles in air and in liquid, providing the potential for particle identification with high specificity, longitudinal studies of changes in particle composition, and characterization of the heterogeneity of individual particles in a population. In this review, we introduce the techniques used to integrate Raman spectroscopy with optical trapping in order to study individual biological particles in liquid and air. We then provide an overview of some of the most promising applications of this technique, highlighting the unique types of measurements enabled by the combination of Raman spectroscopy with optical trapping. Finally, we present a brief discussion of future research directions in the field. PMID:26247952

  1. Raman Spectroscopy and Related Techniques in Biomedicine

    PubMed Central

    Downes, Andrew; Elfick, Alistair

    2010-01-01

    In this review we describe label-free optical spectroscopy techniques which are able to non-invasively measure the (bio)chemistry in biological systems. Raman spectroscopy uses visible or near-infrared light to measure a spectrum of vibrational bonds in seconds. Coherent anti-Stokes Raman (CARS) microscopy and stimulated Raman loss (SRL) microscopy are orders of magnitude more efficient than Raman spectroscopy, and are able to acquire high quality chemically-specific images in seconds. We discuss the benefits and limitations of all techniques, with particular emphasis on applications in biomedicine—both in vivo (using fiber endoscopes) and in vitro (in optical microscopes). PMID:21151763

  2. Diagnosing breast cancer by using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Haka, Abigail S.; Shafer-Peltier, Karen E.; Fitzmaurice, Maryann; Crowe, Joseph; Dasari, Ramachandra R.; Feld, Michael S.

    2005-08-01

    We employ Raman spectroscopy to diagnose benign and malignant lesions in human breast tissue based on chemical composition. In this study, 130 Raman spectra are acquired from ex vivo samples of human breast tissue (normal, fibrocystic change, fibroadenoma, and infiltrating carcinoma) from 58 patients. Data are fit by using a linear combination model in which nine basis spectra represent the morphologic and chemical features of breast tissue. The resulting fit coefficients provide insight into the chemical/morphological makeup of the tissue and are used to develop diagnostic algorithms. The fit coefficients for fat and collagen are the key parameters in the resulting diagnostic algorithm, which classifies samples according to their specific pathological diagnoses, attaining 94% sensitivity and 96% specificity for distinguishing cancerous tissues from normal and benign tissues. The excellent results demonstrate that Raman spectroscopy has the potential to be applied in vivo to accurately classify breast lesions, thereby reducing the number of excisional breast biopsies that are performed. Author contributions: M.F., J.C., R.R.D., and M.S.F. designed research; A.S.H. and K.E.S.-P. performed research; A.S.H. and M.F. analyzed data; and A.S.H. wrote the paper.This paper was submitted directly (Track II) to the PNAS office.Abbreviations: DEH, ductal epithelial hyperplasia; ROC, receiver operating characteristic; N/C, nuclear-to-cytoplasm.

  3. Raman spectroscopy of transition metal dichalcogenides.

    PubMed

    Saito, R; Tatsumi, Y; Huang, S; Ling, X; Dresselhaus, M S

    2016-09-01

    Raman spectroscopy of transition metal dichalcogenides (TMDs) is reviewed based on our recent theoretical and experimental works. First, we discuss the semi-classical and quantum mechanical description for the polarization dependence of Raman spectra of TMDs in which the optical dipole transition matrix elements as a function of laser excitation energy are important for understanding the polarization dependence of the Raman intensity and Raman tensor. Overviewing the symmetry of TMDs, we discuss the dependence of the Raman spectra of TMDs on layer thickness, polarization, laser energy and the structural phase. Furthermore, we discuss the Raman spectra of twisted bilayer and heterostructures of TMDs. Finally, we give our perspectives on the Raman spectroscopy of TMDs. PMID:27388703

  4. Raman spectroscopy of transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

    Saito, R.; Tatsumi, Y.; Huang, S.; Ling, X.; Dresselhaus, M. S.

    2016-09-01

    Raman spectroscopy of transition metal dichalcogenides (TMDs) is reviewed based on our recent theoretical and experimental works. First, we discuss the semi-classical and quantum mechanical description for the polarization dependence of Raman spectra of TMDs in which the optical dipole transition matrix elements as a function of laser excitation energy are important for understanding the polarization dependence of the Raman intensity and Raman tensor. Overviewing the symmetry of TMDs, we discuss the dependence of the Raman spectra of TMDs on layer thickness, polarization, laser energy and the structural phase. Furthermore, we discuss the Raman spectra of twisted bilayer and heterostructures of TMDs. Finally, we give our perspectives on the Raman spectroscopy of TMDs.

  5. Raman spectroscopy application to analyses of components in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhang, Guoping

    2006-09-01

    The characterization of species in aqueous solutions has presented a challenge to analytical and physical chemist, because the JR absorption of the aqueous solvent is so intense that it becomes difficult to observe the solute in the water by JR absorption. In contrast, Raman spectrum of the solute is unaffected by the water, so the weak scattering of water makes the technique well suited to aqueous samples, and the Raman spectrum exhibits well-defined bands corresponding to fundamental modes of vibration. In addition, Raman spectroscopy has some inherent advantages in aqueous solution analysis, because the spectral features of signals from different species are much more distinct, and it provides characteristic signatures for samples, such as blood, protein and cholesterol. All the advantages make Raman spectroscopy be a potential alternative for the study of aqueous solutions. Now, Raman spectroscopy has been applied to studying samples in aqueous solutions, blood serum, intracellular protein levels. Now, industrial wasted water contains many organic contaminants, and it is necessary to determine and monitor these contaminants. The paper first introduces Raman spectroscopy, and then describes its applications to determining the components in aqueous solutions, analyzes and assignes the Raman spectra of o-dichlorobenzene, o-xylene, m-xyiene and p-xylene in detail. The experimental results demonstrate that Raman spectroscopy is a particularly powerful technique for aqueous solutions analyses.

  6. Laser tweezers Raman spectroscopy of single cells

    NASA Astrophysics Data System (ADS)

    Chen, De

    Raman scattering is an inelastic collision between the vibrating molecules inside the sample and the incident photons. During this process, energy exchange takes place between the photon and the scattering molecule. By measuring the energy change of the photon, the molecular vibration mode can be probed. The vibrational spectrum contains valuable information about the disposition of atomic nuclei and chemical bonds within a molecule, the chemical compositions and the interactions between the molecule and its surroundings. In this dissertation, laser tweezers Raman spectroscopy (LTRS) technique is applied for the analysis of biological cells and human cells at single cell level. In LTRS, an individual cell is trapped in aqueous medium with laser tweezers, and Raman scattering spectra from the trapped cell are recorded in real-time. The Raman spectra of these cells can be used to reveal the dynamical processes of cell growth, cell response to environment changes, and can be used as the finger print for the identification of a bacterial cell species. Several biophysical experiments were carried out using LTRS: (1) the dynamic germination process of individual spores of Bacillus thuringiensis was detected via Ca-DPA, a spore-specific biomarker molecule; (2) inactivation and killing of Bacillus subtilis spores by microwave irradiation and wet heat were studied at single cell level; (3) the heat shock activation process of single B. subtilis spores were analyzed, in which the reversible transition from glass-like state at low temperature to liquid-like state at high temperature in spore was revealed at the molecular level; (4) the kinetic processes of bacterial cell lysis of E. coli by lysozyme and by temperature induction of lambda phage were detected real-time; (5) the fixation and rehydration of human platelets were quantitatively evaluated and characterized with Raman spectroscopy method, which provided a rapid way to quantify the quality of freeze-dried therapeutic

  7. Isolation and identification of bacteria by means of Raman spectroscopy.

    PubMed

    Pahlow, Susanne; Meisel, Susann; Cialla-May, Dana; Weber, Karina; Rösch, Petra; Popp, Jürgen

    2015-07-15

    Bacterial detection is a highly topical research area, because various fields of application will benefit from the progress being made. Consequently, new and innovative strategies which enable the investigation of complex samples, like body fluids or food stuff, and improvements regarding the limit of detection are of general interest. Within this review the prospects of Raman spectroscopy as a reliable tool for identifying bacteria in complex samples are discussed. The main emphasis of this work is on important aspects of applying Raman spectroscopy for the detection of bacteria like sample preparation and the identification process. Several approaches for a Raman compatible isolation of bacterial cells have been developed and applied to different matrices. Here, an overview of the limitations and possibilities of these methods is provided. Furthermore, the utilization of Raman spectroscopy for diagnostic purposes, food safety and environmental issues is discussed under a critical view. PMID:25895619

  8. Raman spectroscopy: the gateway into tomorrow's virology.

    PubMed

    Lambert, Phelps J; Whitman, Audy G; Dyson, Ossie F; Akula, Shaw M

    2006-01-01

    In the molecular world, researchers act as detectives working hard to unravel the mysteries surrounding cells. One of the researchers' greatest tools in this endeavor has been Raman spectroscopy. Raman spectroscopy is a spectroscopic technique that measures the unique Raman spectra for every type of biological molecule. As such, Raman spectroscopy has the potential to provide scientists with a library of spectra that can be used to unravel the makeup of an unknown molecule. However, this technique is limited in that it is not able to manipulate particular structures without disturbing their unique environment. Recently, a novel technology that combines Raman spectroscopy with optical tweezers, termed Raman tweezers, evades this problem due to its ability to manipulate a sample without physical contact. As such, Raman tweezers has the potential to become an incredibly effective diagnostic tool for differentially distinguishing tissue, and therefore holds great promise in the field of virology for distinguishing between various virally infected cells. This review provides an introduction for a virologist into the world of spectroscopy and explores many of the potential applications of Raman tweezers in virology. PMID:16805914

  9. Raman spectroscopy: the gateway into tomorrow's virology

    PubMed Central

    Lambert, Phelps J; Whitman, Audy G; Dyson, Ossie F; Akula, Shaw M

    2006-01-01

    In the molecular world, researchers act as detectives working hard to unravel the mysteries surrounding cells. One of the researchers' greatest tools in this endeavor has been Raman spectroscopy. Raman spectroscopy is a spectroscopic technique that measures the unique Raman spectra for every type of biological molecule. As such, Raman spectroscopy has the potential to provide scientists with a library of spectra that can be used to unravel the makeup of an unknown molecule. However, this technique is limited in that it is not able to manipulate particular structures without disturbing their unique environment. Recently, a novel technology that combines Raman spectroscopy with optical tweezers, termed Raman tweezers, evades this problem due to its ability to manipulate a sample without physical contact. As such, Raman tweezers has the potential to become an incredibly effective diagnostic tool for differentially distinguishing tissue, and therefore holds great promise in the field of virology for distinguishing between various virally infected cells. This review provides an introduction for a virologist into the world of spectroscopy and explores many of the potential applications of Raman tweezers in virology. PMID:16805914

  10. Study of virus by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Moor, K.; Kitamura, H.; Hashimoto, K.; Sawa, M.; Andriana, B. B.; Ohtani, K.; Yagura, T.; Sato, H.

    2013-02-01

    Problem of viruses is very actual for nowadays. Some viruses, which are responsible for human of all tumors, are about 15 %. Main purposes this study, early detection virus in live cell without labeling and in the real time by Raman spectroscopy. Micro Raman spectroscopy (mRs) is a technique that uses a Raman spectrometer to measure the spectra of microscopic samples. According to the Raman spectroscopy, it becomes possible to study the metabolites of a live cultured cell without labeling. We used mRs to detect the virus via HEK 293 cell line-infected adenovirus. We obtained raman specters of lives cells with viruses in 24 hours and 7 days after the infection. As the result, there is some biochemical changing after the treatment of cell with virus. One of biochemical alteration is at 1081 cm-1. For the clarification result, we use confocal fluorescent microscopy and transmission electron microscopy (TEM).

  11. Inverse Raman bands in ultrafast Raman loss spectroscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Xueqiong; Li, Xiuting; Niu, Kai; Lee, Soo-Y.

    2011-10-01

    Ultrafast Raman loss spectroscopy (URLS) is equivalent to anti-Stokes femtosecond stimulated Raman spectroscopy (FSRS), using a broadband probe pulse that extends to the blue of the narrow bandwidth Raman pump, and can be described as inverse Raman scattering (IRS). Using the Feynman dual time-line diagram, the third-order polarization for IRS with finite pulses can be written down in terms of a four-time correlation function. An analytic expression is obtained for the latter in the harmonic approximation which facilitates computation. We simulated the URLS of crystal violet (CV) for various resonance Raman pump excitation wavelengths using the IRS polarization expression with finite pulses. The calculated results agreed well with the experimental results of S. Umapathy et al., J. Chem. Phys. 133, 024505 (2010). In the limit of monochromatic Raman pump and probe pulses, we obtain the third-order susceptibility for multi-modes, and for a single mode we recover the well-known expression for the third-order susceptibility, χ _{IRS}^{(3)}, for IRS. The latter is used to understand the mode dependent phase changes as a function of Raman pump excitation in the URLS of CV.

  12. Emerging Dental Applications of Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Choo-Smith, Lin-P'ing; Hewko, Mark; Sowa, Michael G.

    Until recently, the application of Raman spectroscopy to investigate dental tissues has primarily focused on using microspectroscopy to characterize dentin and enamel structures as well as to understand the adhesive interface of various resin and bonding agents used in restorative procedures. With the advent of improved laser, imaging/mapping and fibre optic technologies, the applications have expanded to investigate various biomedical problems ranging from oral cancer, bacterial identification and early dental caries detection. The overall aim of these applications is to develop Raman spectroscopy into a tool for use in the dental clinic. This chapter presents the recent dental applications of Raman spectroscopy as well as discusses the potential, strengths and limitations of the technology in comparison with alternative techniques. In addition, a discussion and rationale about combining Raman spectroscopy with other optical techniques will be included.

  13. Micro-mirror arrays for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Duncan, W. M.

    2015-03-01

    In this research we study Raman and fluorescence spectroscopies as non-destructive and noninvasive methods for probing biological material and "living systems." Particularly for a living material any probe need be non-destructive and non-invasive, as well as provide real time measurement information and be cost effective to be generally useful. Over the past few years the components needed to measure weak and complex processes such as Raman scattering have evolved substantially with the ready availability of lasers, dichroic filters, low noise and sensitive detectors, digitizers and signal processors. A Raman spectrum consists of a wavelength or frequency spectrum that corresponds to the inelastic (Raman) photon signal that results from irradiating a "Raman active" material. Raman irradiation of a material usually and generally uses a single frequency laser. The Raman fingerprint spectrum that results from a Raman interaction can be determined from the frequencies scattered and received by an appropriate detector. Spectra are usually "digitized" and numerically matched to a reference sample or reference material spectra in performing an analysis. Fortunately today with the many "commercial off-the-shelf" components that are available, weak intensity effects such as Raman and fluorescence spectroscopy can be used for a number of analysis applications. One of the experimental limitations in Raman measurement is the spectrometer itself. The spectrometer is the section of the system that either by interference plus detection or by dispersion plus detection that "signal" amplitude versus energy/frequency signals are measured. Particularly in Raman spectroscopy, optical signals carrying desired "information" about the analyte are extraordinarily weak and require special considerations when measuring. We will discuss here the use of compact spectrometers and a micro-mirror array system (used is the digital micro-mirror device (DMD) supplied by the DLP® Products group of

  14. Occlusal caries detection using polarized Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ionita, I.; Bulou, A.

    2008-02-01

    The tooth enamel, because of its hydroxyapatite composition, must present a Raman spectrum with strong polarization anisotropy. Carious lesions of the enamel will produce an alteration of local symmetry and will increase much more scattering of light. This will reduce the anisotropy of the Raman spectra. Because of the difference between high sensitivity to polarization of the 959 cm -1 Raman peak in sound enamel and low sensitivity in carried enamel, Raman polarized spectroscopy could be a useful method to early detect teeth caries.

  15. Raman spectroscopy and polarization: Selected case studies

    NASA Astrophysics Data System (ADS)

    Ossikovski, Razvigor; Picardi, Gennaro; Ndong, Gérald; Chaigneau, Marc

    2012-10-01

    We show, through several selected case studies, the potential benefits that can be obtained by controlling the polarization states of the exciting and scattered radiations in a Raman scattering experiment. When coupled with polarization control, Raman spectroscopy is thus capable of providing extra information on the structural properties of the materials under investigation. The experimental examples presented in this work are taken from the area of both conventional, i.e., far-field, as well as from near-field Raman spectroscopy. They cover topics such as the stress tensor measurement in strained semiconductor structures, the vibration mode assignment in pentacene thin films and the Raman scattering tensor determination from near-field measurements on azobenzene monolayers. The basic theory necessary for modelling the far- and near-field polarized Raman responses is also given and the model efficiency is illustrated on the experimental data.

  16. Applications of Raman spectroscopy to gemology.

    PubMed

    Bersani, Danilo; Lottici, Pier Paolo

    2010-08-01

    Being nondestructive and requiring short measurement times, a low amount of material, and no sample preparation, Raman spectroscopy is used for routine investigation in the study of gemstone inclusions and treatments and for the characterization of mounted gems. In this work, a review of the use of laboratory Raman and micro-Raman spectrometers and of portable Raman systems in the gemology field is given, focusing on gem identification and on the evaluation of the composition, provenance, and genesis of gems. Many examples are shown of the use of Raman spectroscopy as a tool for the identification of imitations, synthetic gems, and enhancement treatments in natural gemstones. Some recent developments are described, with particular attention being given to the semiprecious stone jade and to two important organic materials used in jewelry, i.e., pearls and corals. PMID:20419294

  17. Difference Raman spectroscopy of DNA molecules

    NASA Astrophysics Data System (ADS)

    Anokhin, Andrey S.; Gorelik, Vladimir S.; Dovbeshko, Galina I.; Pyatyshev, Alexander Yu; Yuzyuk, Yury I.

    2015-01-01

    In this paper the micro-Raman spectra of calf DNA for different points of DNA sample have been recorded. The Raman spectra were made with help of difference Raman spectroscopy technique. Raman spectra were recorded with high spatial resolution from different points of the wet and dry samples in different spectral range (100÷4000cm-1) using two lasers: argon (514.5 nm) and helium -neon (632.8 nm). The significant differences in the Raman spectra for dry and wet DNA and for different points of DNA molecules were observed. The obtained data on difference Raman scattering spectra of DNA molecules may be used for identification of DNA types and for analysis of genetic information associated with the molecular structure of this molecule.

  18. Mobile Raman spectroscopy in astrobiology research.

    PubMed

    Vandenabeele, Peter; Jehlička, Jan

    2014-12-13

    Raman spectroscopy has proved to be a very useful technique in astrobiology research. Especially, working with mobile instrumentation during fieldwork can provide useful experiences in this field. In this work, we provide an overview of some important aspects of this research and, apart from defining different types of mobile Raman spectrometers, we highlight different reasons for this research. These include gathering experience and testing of mobile instruments, the selection of target molecules and to develop optimal data processing techniques for the identification of the spectra. We also identify the analytical techniques that it would be most appropriate to combine with Raman spectroscopy to maximize the obtained information and the synergy that exists with Raman spectroscopy research in other research areas, such as archaeometry and forensics. PMID:25368355

  19. Raman spectroscopy at the tritium laboratory Karlsruhe

    SciTech Connect

    Schloesser, M.; Bornschein, B.; Fischer, S.; Kassel, F.; Rupp, S.; Sturm, M.; James, T.M.; Telle, H.H.

    2015-03-15

    Raman spectroscopy is employed successfully for analysis of hydrogen isotopologues at the Tritium Laboratory Karlsruhe (TLK). Raman spectroscopy is based on the inelastic scattering of photons off molecules. Energy is transferred to the molecules as rotational/vibrational excitation being characteristic for each type of molecule. Thus, qualitative analysis is possible from the Raman shifted light, while quantitative information can be obtained from the signal intensities. After years of research and development, the technique is now well-advanced providing fast (< 10 s), precise (< 0.1%) and true (< 3%) compositional analysis of gas mixtures of hydrogen isotopologues. In this paper, we summarize the recent achievements in the further development on this technique, and the various applications for which it is used at TLK. Raman spectroscopy has evolved as a versatile, highly accurate key method for quantitative analysis complementing the port-folio of analytic techniques at the TLK.

  20. Using Raman spectroscopy to characterize biological materials.

    PubMed

    Butler, Holly J; Ashton, Lorna; Bird, Benjamin; Cinque, Gianfelice; Curtis, Kelly; Dorney, Jennifer; Esmonde-White, Karen; Fullwood, Nigel J; Gardner, Benjamin; Martin-Hirsch, Pierre L; Walsh, Michael J; McAinsh, Martin R; Stone, Nicholas; Martin, Francis L

    2016-04-01

    Raman spectroscopy can be used to measure the chemical composition of a sample, which can in turn be used to extract biological information. Many materials have characteristic Raman spectra, which means that Raman spectroscopy has proven to be an effective analytical approach in geology, semiconductor, materials and polymer science fields. The application of Raman spectroscopy and microscopy within biology is rapidly increasing because it can provide chemical and compositional information, but it does not typically suffer from interference from water molecules. Analysis does not conventionally require extensive sample preparation; biochemical and structural information can usually be obtained without labeling. In this protocol, we aim to standardize and bring together multiple experimental approaches from key leaders in the field for obtaining Raman spectra using a microspectrometer. As examples of the range of biological samples that can be analyzed, we provide instructions for acquiring Raman spectra, maps and images for fresh plant tissue, formalin-fixed and fresh frozen mammalian tissue, fixed cells and biofluids. We explore a robust approach for sample preparation, instrumentation, acquisition parameters and data processing. By using this approach, we expect that a typical Raman experiment can be performed by a nonspecialist user to generate high-quality data for biological materials analysis. PMID:26963630

  1. Raman spectroscopy of white wines.

    PubMed

    Martin, Coralie; Bruneel, Jean-Luc; Guyon, François; Médina, Bernard; Jourdes, Michael; Teissedre, Pierre-Louis; Guillaume, François

    2015-08-15

    The feasibility of exploiting Raman scattering to analyze white wines has been investigated using 3 different wavelengths of the incoming laser radiation in the near-UV (325 nm), visible (532 nm) and near infrared (785 nm). To help in the interpretation of the Raman spectra, the absorption properties in the UV-visible range of two wine samples as well as their laser induced fluorescence have also been investigated. Thanks to the strong intensity enhancement of the Raman scattered light due to electronic resonance with 325 nm laser excitation, hydroxycinnamic acids may be detected and analyzed selectively. Fructose and glucose may also be easily detected below ca. 1000 cm(-1). This feasibility study demonstrates the potential of the Raman spectroscopic technique for the analysis of white wines. PMID:25794745

  2. Emerging technology: applications of Raman spectroscopy for prostate cancer.

    PubMed

    Kast, Rachel E; Tucker, Stephanie C; Killian, Kevin; Trexler, Micaela; Honn, Kenneth V; Auner, Gregory W

    2014-09-01

    There is a need in prostate cancer diagnostics and research for a label-free imaging methodology that is nondestructive, rapid, objective, and uninfluenced by water. Raman spectroscopy provides a molecular signature, which can be scaled from micron-level regions of interest in cells to macroscopic areas of tissue. It can be used for applications ranging from in vivo or in vitro diagnostics to basic science laboratory testing. This work describes the fundamentals of Raman spectroscopy and complementary techniques including surface enhanced Raman scattering, resonance Raman spectroscopy, coherent anti-Stokes Raman spectroscopy, confocal Raman spectroscopy, stimulated Raman scattering, and spatially offset Raman spectroscopy. Clinical applications of Raman spectroscopy to prostate cancer will be discussed, including screening, biopsy, margin assessment, and monitoring of treatment efficacy. Laboratory applications including cell identification, culture monitoring, therapeutics development, and live imaging of cellular processes are discussed. Potential future avenues of research are described, with emphasis on multiplexing Raman spectroscopy with other modalities. PMID:24510129

  3. Anisotropic Raman Spectroscopy of Few-Layer Phosphorene

    NASA Astrophysics Data System (ADS)

    Du, Yuchen; Wu, Wangran; Maassen, Jesse; Luo, Zhe; Lundstrom, Mark; Xu, Xianfan; Ye, Peide

    Much recent research of black phosphorus (BP) and phosphorene has been focused on their unique anisotropy of this novel 2D material in terms of electrical, optical and thermal properties. Here we report the emerging Raman spectroscopy measurements of BP with respect to its isolation from bulk BP down to single layer phosphorene. The found frequency shift of BP in Raman spectra is to be correlated with atomic motion of modes, which can be explained by applying classical model of coupled harmonic oscillators. Raman intensity of different modes has also been included in our studies, which is confirmed as a solid strategy to quickly determine BP layer thickness. In addition, more information of their mechanical properties can also be obtained from Raman spectroscopy. The work was supported in part by NSF ECCS-1449270, NSF/AFOSR EFRI 2DARE Program, and ARO W911NF-15-1-0574.

  4. Airborne chemistry coupled to Raman spectroscopy.

    PubMed

    Santesson, Sabina; Johansson, Jonas; Taylor, Lynne S; Levander, Ia; Fox, Shannon; Sepaniak, Michael; Nilsson, Staffan

    2003-05-01

    In this paper, the use of airborne chemistry (acoustically levitated drops) in combination with Raman spectroscopy is explored. We report herein the first Raman studies of crystallization processes in levitated drops and the first demonstration of surface-enhanced Raman scattering (SERS) detection in this medium. Crystallization studies on the model compounds benzamide and indomethacin resulted in the formation of two crystal modifications for each compound, suggesting that this methodology may be useful for investigation of polymorphs. SERS detection resulted in a signal enhancement of 27 000 for benzoic acid and 11 000 for rhodamine 6-G. The preliminary results presented here clearly indicate that several important applications of the combination between Raman spectroscopy and acoustic drop levitation can be expected in the future. PMID:12720359

  5. Multiplex coherent raman spectroscopy detector and method

    NASA Technical Reports Server (NTRS)

    Chen, Peter (Inventor); Joyner, Candace C. (Inventor); Patrick, Sheena T. (Inventor); Guyer, Dean R. (Inventor)

    2004-01-01

    A multiplex coherent Raman spectrometer (10) and spectroscopy method rapidly detects and identifies individual components of a chemical mixture separated by a separation technique, such as gas chromatography. The spectrometer (10) and method accurately identify a variety of compounds because they produce the entire gas phase vibrational Raman spectrum of the unknown gas. This is accomplished by tilting a Raman cell (20) to produce a high-intensity, backward-stimulated, coherent Raman beam of 683 nm, which drives a degenerate optical parametric oscillator (28) to produce a broadband beam of 1100-1700 nm covering a range of more than 3000 wavenumber. This broadband beam is combined with a narrowband beam of 532 nm having a bandwidth of 0.003 wavenumbers and focused into a heated windowless cell (38) that receives gases separated by a gas chromatograph (40). The Raman radiation scattered from these gases is filtered and sent to a monochromator (50) with multichannel detection.

  6. Multiplex coherent raman spectroscopy detector and method

    DOEpatents

    Chen, Peter; Joyner, Candace C.; Patrick, Sheena T.; Guyer, Dean R.

    2004-06-08

    A multiplex coherent Raman spectrometer (10) and spectroscopy method rapidly detects and identifies individual components of a chemical mixture separated by a separation technique, such as gas chromatography. The spectrometer (10) and method accurately identify a variety of compounds because they produce the entire gas phase vibrational Raman spectrum of the unknown gas. This is accomplished by tilting a Raman cell (20) to produce a high-intensity, backward-stimulated, coherent Raman beam of 683 nm, which drives a degenerate optical parametric oscillator (28) to produce a broadband beam of 1100-1700 nm covering a range of more than 3000 wavenumber. This broadband beam is combined with a narrowband beam of 532 nm having a bandwidth of 0.003 wavenumbers and focused into a heated windowless cell (38) that receives gases separated by a gas chromatograph (40). The Raman radiation scattered from these gases is filtered and sent to a monochromator (50) with multichannel detection.

  7. Potential of Raman and Infrared Spectroscopy for Plant Analysis

    NASA Astrophysics Data System (ADS)

    Schulz, H.

    2008-11-01

    Various mid-infrared (MIR) and Raman spectroscopic methods applied to the analysis of valuable plant substances or quality parameters in selected horticultural and agricultural crops are presented. Generally, both spectroscopy techniques allow to identify simultaneously characteristic key bands of individual plant components (e.g. carotenoids, alkaloids, polyacetylenes, fatty acids, amino acids, terpenoids). In contrast to MIR methods Raman spectroscopy mostly does not need any sample pre-treatment; even fresh plant material can be analysed without difficulty because water shows only weak Raman scattering properties. In some cases a significant sensivity enhancement of Raman signals can be achieved if the exciting laser wavelength is adjusted to the absorption range of particular plant chromophores such as carotenoids (Resonance Raman effect). Applying FT-IR or FT Raman micro-spectroscopy the distribution of certain plant constituents in the cell wall can be identified without the need for any physical separation. Furthermore it is also possible to analyse secondary metabolites occurring in the cell vacuoles if significant key bands do not coincide with the spectral background of the plant matrix.

  8. Identification of gemstone treatments with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kiefert, Lore; Haenni, Henry A.; Chalain, Jean-Pierre

    2000-09-01

    The newest gemstone treatment concerns brownish diamonds of type IIa. These can be improved to near colorless by an enhancement process developed by General Electric, USA, using high temperature and pressure. A comparison of Raman spectroscopic features in the visible area (luminescence bands) of both treated and untreated colorless diamonds is given. Finally, examples of artificially colored peals and corals and their detection with Raman spectroscopy are shown.

  9. Analysis of lipsticks using Raman spectroscopy.

    PubMed

    Gardner, P; Bertino, M F; Weimer, R; Hazelrigg, E

    2013-10-10

    In this study, 80 lipsticks were obtained and evaluated using Raman spectroscopy at excitation wavelengths of 532 and 780 nm. Fluorescence severely limited analysis with the 532 nm line while the 780 nm line proved useful for all samples analyzed. It was possible to differentiate 95% of the lipsticks evaluated based on one or more Raman peaks. However, there were no peak trends observed that could be used to identify a manufacturer or categorize a sample. In situ analysis of lipstick smears was found to be possible even from several Raman active substrates, but was occasionally limited by background fluorescence and in extreme cases, photodegradation. PMID:24053867

  10. Raman spectroscopy under extreme conditions

    SciTech Connect

    Goncharov, A F; Crowhurst, J C

    2004-11-05

    We report the results of Raman measurements of various materials under simultaneous conditions of high temperature and high pressure in the diamond anvil cell (DAC). High temperatures are generated by laser heating or internal resistive (ohmic) heating or a combination of both. We present Raman spectra of cubic boron nitride (cBN) to 40 GPa and up to 2300 K that show a continuous pressure and temperature shift of the frequency of the transverse optical mode. We have also obtained high-pressure Raman spectra from a new noble metal nitride, which we synthesized at approximately 50 GPa and 2000 K. We have obtained high-temperature spectra from pure nitrogen to 39 GPa and up to 2000 K, which show the presence of a hot band that has previously been observed in CARS measurements. These measurements have also allowed us to constrain the melting curve and to examine changes in the intramolecular potential with pressure.

  11. Raman and multichannel Raman spectroscopy of biological systems

    NASA Astrophysics Data System (ADS)

    Bertoluzza, Alessandro; Caramazza, R.; Fagnano, C.

    1991-05-01

    Raman and multichannel Raman spectroscopy are molecular techniques able to monitor the bulk and surface structure of a biomaterial, in a non destructive and non invasive way, giving therefore useful information on physical and chemical aspects of biocompatibility. The same techniques can also be adequately used for the characterization of the biomaterial-host tissue interface, hence providing structural information on the biochemical aspect of biocompatibility. Moreover, multichannel Raman spectroscopy can also determine "in vivo" and "in situ" the bulk and surface structure of a biomaterial and the molecular interactions between biomaterials and tissues. Useful information at a molecular level on the biomaterial-tissue system can so be deduced. In particular, the application of traditional Paman spectroscopy to bioactive glasses (glasses derived from Hench's bioglass and meta and oligophosphates of calcium by themselves and with the addition of sodium and aluminium) useful in orthopedics and the application to hydrophobic (PMMA) and hydrophilic (PHEMA and PVP) organic polymers useful in ophthalmology are shown. Instead the applications of multichannel Paman spectroscopy are elucidated in the case of intraocular lenses (lOLs) based on PMMA and contact lenses (CLs) based on hydrophi I ic polymers.

  12. Coherent Raman spectroscopy for supersonic flow measurments

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1986-01-01

    In collaboration with NASA/Langley Research Center, a truly nonintrusive and nonseeding method for measuring supersonic molecular flow parameters was proposed and developed at Colorado State University. The feasibility of this Raman Doppler Velocimetry (RDV), currently operated in a scanning mode, was demonstrated not only in a laboratory environment at Colorado State University, but also in a major wind tunnel at NASA/Langley Research Center. The research progress of the RDV development is summarized. In addition, methods of coherent Rayleigh-Brillouin spectroscopy and single-pulse coherent Raman spectroscopy are investigated, respectively, for measurements of high-pressure and turbulent flows.

  13. High fidelity nanohole enhanced Raman spectroscopy.

    SciTech Connect

    Bahns, J. T.; Guo, Q.; Gray, S. K.; Jaeger, H. M.; Chen, L.; Montgomery, J. M.; Univ. of Chicago

    2009-01-01

    Surface enhanced Raman spectroscopy (SERS) is a sensitive technique that can even detect single molecules. However, in many SERS applications, the strongly inhomogeneous distribution of intense local fields makes it very difficult for a quantitive assessment of the fidelity, or reproducibility of the signal, which limits the application of SERS. Herein, we report the development of exceptionally high-fidelity hole-enhanced Raman spectroscopy (HERS) from ordered, 2D hexagonal nanohole arrays. We take the fidelity f to be a measure of the percent deviation of the Raman peaks from measurement to measurement. Overall, area averaged fidelities for 12 gold array samples ranged from f {approx} 2-15% for HERS using aqueous R6G molecules. Furthermore, intensity modulations of the enhanced Raman spectra were measured for the first time as a function of polarization angle. The best of these measurements, which focus on static laser spots on the sample, could be consistent with even higher fidelities than the area-averaged results. Nanohole arrays in silver provided supporting polarization measurements and a more complete enhanced Raman fingerprint for phenylalanine molecules. We also carried out finite-difference time-domain calculations to assist in the interpretation of the experiments, identifying the polarization dependence as possibly arising from hole-hole interactions. Our results represent a step toward making quantitative and reproducible enhanced Raman measurements possible and also open new avenues for a large-scale source of highly uniform hot spots.

  14. Theory of femtosecond stimulated Raman spectroscopy.

    PubMed

    Lee, Soo-Y; Zhang, Donghui; McCamant, David W; Kukura, Philipp; Mathies, Richard A

    2004-08-22

    Femtosecond broadband stimulated Raman spectroscopy (FSRS) is a new technique that produces high-resolution (time-resolved) vibrational spectra from either the ground or excited electronic states of molecules, free from background fluorescence. FSRS uses simultaneously a narrow bandwidth approximately 1-3 ps Raman pump pulse with a continuum approximately 30-50 fs Stokes probe pulse to produce sharp Raman gains, at positions corresponding to vibrational transitions in the sample, riding on top of the continuum Stokes probe spectrum. When FSRS is preceded by a femtosecond actinic pump pulse that initiates the photochemistry of interest, time-resolved Raman spectroscopy can be carried out. We present two theoretical approaches to FSRS: one is based on a coupling of Raman pump and probe light waves with the vibrations in the medium, and another is a quantum-mechanical description. The latter approach is used to discuss the conditions of applicability and limitations of the coupled-wave description. Extension of the quantum-mechanical description to the case where the Raman pump beam is on resonance with an excited electronic state, as well as when FSRS is used to probe a nonstationary vibrational wave packet prepared by an actinic pump pulse, is also discussed. PMID:15303930

  15. Endoscopic Raman Spectroscopy for Molecular Fingerprinting of Gastric Cancer: Principle to Implementation

    PubMed Central

    2015-01-01

    Currently, positive endoscopic biopsy is the standard criterion for gastric cancer diagnosis but is invasive, often inconsistent, and delayed although early detection and early treatment is the most important policy. Raman spectroscopy is a spectroscopic technique based on inelastic scattering of monochromatic light. Raman spectrum represents molecular composition of the interrogated volume providing a direct molecular fingerprint. Several investigations revealed that Raman spectroscopy can differentiate normal, dysplastic, and adenocarcinoma gastric tissue with high sensitivity and specificity. Moreover, this technique can indentify malignant ulcer and showed the capability to analyze the carcinogenesis process. Automated on-line Raman spectral diagnostic system raised possibility to use Raman spectroscopy in clinical field. Raman spectroscopy can be applied in many fields such as guiding a target biopsy, optical biopsy in bleeding prone situation, and delineating the margin of the lesion. With wide field technology, Raman spectroscopy is expected to have specific role in our future clinical field. PMID:26106612

  16. Disposable sheath that facilitates endoscopic Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Short, Michael; Tai, Isabella T.; Zeng, Haishan

    2016-02-01

    In vivo endoscopic Raman spectroscopy of human tissue using a fiber optic probe has been previously demonstrated. However, there remain several technical challenges, such as a robust control over the laser radiation dose and measurement repeatability during endoscopy. A decrease in the signal to noise was also observed due to aging of Raman probe after repeated cycles of harsh reprocessing procedures. To address these issues, we designed and tested a disposable, biocompatible, and sterile sheath for use with a fiber optic endoscopic Raman probe. The sheath effectively controls contamination of Raman probes between procedures, greatly reduces turnaround time, and slows down the aging of the Raman probes. A small optical window fitted at the sheath cap maintained the measurement distance between Raman probe end and tissue surface. To ensure that the sheath caused a minimal amount of fluorescence and Raman interference, the optical properties of materials for the sheath, optical window, and bonding agent were studied. The easy-to-use sheath can be manufactured at a moderate cost. The sheath strictly enforced a maximum permissible exposure standard of the tissue by the laser and reduced the spectral variability by 1.5 to 8.5 times within the spectral measurement range.

  17. Raman Spectroscopy Cell-based Biosensors

    PubMed Central

    Notingher, Ioan

    2007-01-01

    One of the main challenges faced by biodetection systems is the ability to detect and identify a large range of toxins at low concentrations and in short times. Cell-based biosensors rely on detecting changes in cell behaviour, metabolism, or induction of cell death following exposure of live cells to toxic agents. Raman spectroscopy is a powerful technique for studying cellular biochemistry. Different toxic chemicals have different effects on living cells and induce different time-dependent biochemical changes related to cell death mechanisms. Cellular changes start with membrane receptor signalling leading to cytoplasmic shrinkage and nuclear fragmentation. The potential advantage of Raman spectroscopy cell-based systems is that they are not engineered to respond specifically to a single toxic agent but are free to react to many biologically active compounds. Raman spectroscopy biosensors can also provide additional information from the time-dependent changes of cellular biochemistry. Since no cell labelling or staining is required, the specific time dependent biochemical changes in the living cells can be used for the identification and quantification of the toxic agents. Thus, detection of biochemical changes of cells by Raman spectroscopy could overcome the limitations of other biosensor techniques, with respect to detection and discrimination of a large range of toxic agents. Further developments of this technique may also include integration of cellular microarrays for high throughput in vitro toxicological testing of pharmaceuticals and in situ monitoring of the growth of engineered tissues.

  18. Applications of high resolution inverse Raman spectroscopy

    SciTech Connect

    Owyoung, A.; Esherick, P.

    1980-01-01

    The use of high-power, narrow-band lasers has significantly improved the resolving power and sensitivity of inverse Raman spectroscopy of gases. In this paper we shall describe this technique, illustrate its capabilities by showing some Q-branch spectra of heavy spherical tops, and survey some possible future applications.

  19. Raman Spectroscopy of Bone and Cartilage

    NASA Astrophysics Data System (ADS)

    Morris, Michael

    This chapter will reviews the Raman spectroscopy of the subject tissues. After a brief introduction to the structure, biology, and function of these tissues, we will describe the spectra and band assignments of the tissues and then summarize applications to studies of tissue development, mechanical function and competence, and pathology. Both metabolic diseases and genetic disorders will be covered.

  20. Raman spectroscopy of shocked water

    SciTech Connect

    Holmes, N.C.; Nellis, W.J.; Graham, W.B.; Walrafen, G.E.

    1985-08-01

    We describe a new technique for recording spontaneous Raman spectra from molecules during the passage of strong shock waves. We have used this technique to study the OH-stretch band of liquid H/sub 2/O shocked to pressure up to 26 GPa and 1700 K. The shape of the band changes over the range 7.5-26 GPa, and is described well by a two-component mixture model, implying changes in the intermolecular coupling of shock compressed water molecules. We discuss the implications of the spectra on the mechanism responsible for the electrical conductivity of shocked H/sub 2/O. 22 refs., 7 figs., 2 tabs.

  1. Raman spectroscopy of saliva as a perspective method for periodontitis diagnostics Raman spectroscopy of saliva

    NASA Astrophysics Data System (ADS)

    Gonchukov, S.; Sukhinina, A.; Bakhmutov, D.; Minaeva, S.

    2012-01-01

    In view of its potential for biological tissues analyses at a molecular level, Raman spectroscopy in optical range has been the object of biomedical research for the last years. The main aim of this work is the development of Raman spectroscopy for organic content identifying and determination of biomarkers of saliva at a molecular level for periodontitis diagnostics. Four spectral regions were determined: 1155 and 1525 cm-1, 1033 and 1611 cm-1, which can be used as biomarkers of this widespread disease.

  2. Detection Of Biochips By Raman And Surface Enhanced Raman Spectroscopies

    NASA Astrophysics Data System (ADS)

    Kantarovich, Keren; Tsarfati, Inbal; Gheber, Levi A.; Haupt, Karsten; Bar, Ilana

    2010-08-01

    Biochips constitute a rapidly increasing research field driven by the versatility of sensing devices and the importance of their applications in the bioanalytical field, drug development, environmental monitoring, food analysis, etc. Common strategies used for creating biochips and for reading them have extensive limitations, motivating development of miniature biochips and label-free formats. To achieve these goals we combined the nano fountain pen method, for printing microscale features with Raman spectroscopy or surface enhanced Raman spectroscopy (SERS) for reading droplets of synthetic receptors. These receptors include molecularly imprinted polymers (MIPs), which are obtained by polymerization of suitable functional and cross-linking monomers around molecular templates. MIPs are characterized by higher physical and chemical stability than biomacromolecules, and therefore are potentially very suitable as recognition elements for biosensors, or biochips. The monitored bands in the Raman and SERS spectra could be related to the taken up compound, allowing direct detection of the template, i.e., the β-blocking drug propranolol in the imprinted droplets, as well as imaging of individual and multiple dots in an array. This study shows that the combination of nanolithography techniques with SERS might open the possibility of miniaturized arrayed MIP sensors with label-free, specific and quantitative detection.

  3. Raman spectroscopy of Alzheimer's diseased tissue

    NASA Astrophysics Data System (ADS)

    Sudworth, Caroline D.; Krasner, Neville

    2004-07-01

    Alzheimer's disease is one of the most common forms of dementia, and causes steady memory loss and mental regression. It is also accompanied by severe atrophy of the brain. However, the pathological biomarkers of the disease can only be confirmed and examined upon the death of the patient. A commercial (Renishaw PLC, UK) Raman system with an 830 nm NIR diode laser was used to analyse brain samples, which were flash frozen at post-mortem. Ethical approval was sought for these samples. The Alzheimer's diseased samples contained a number of biomarkers, including neuritic plaques and tangles. The Raman spectra were examined by order to differentiate between normal and Alzheimer's diseased brain tissues. Preliminary results indicate that Alzheimer's diseased tissues can be differentiated from control tissues using Raman spectroscopy. The Raman spectra differ in terms of peak intensity, and the presence of a stronger amide I band in the 1667 cm-1 region which occurs more prominently in the Alzheimer's diseased tissue. These preliminary results indicate that the beta-amyloid protein originating from neuritic plaques can be identified with Raman spectroscopy.

  4. Monitoring lignocellulosic bioethanol production processes using Raman spectroscopy.

    PubMed

    Iversen, Jens A; Ahring, Birgitte K

    2014-11-01

    Process control automation in the emerging biorefinery industry may be achieved by applying effective methods for monitoring compound concentrations during the production processes. This study examines the application of Raman spectroscopy with an excitation wavelength of 785nm and an immersion probe for in situ monitoring the progression of pretreatment, hydrolysis and fermentation processes in the production of lignocellulosic ethanol. Raman signals were attenuated by light scattering cells and lignocellulosic particulates, which the quantification method to some degree could correct for by using an internal standard in the spectra. Allowing particulates to settle by using a slow stirring speed further improved results, suggesting that Raman spectroscopy should be used in combination with continuous separation when used to monitor process mixtures with large amounts of particulates. The root mean square error of prediction (RMSE) of ethanol and glucose measured in real-time was determined to be 0.98g/L and 1.91g/L respectively. PMID:25255187

  5. Raman spectroscopy of 'Bisphenol A'

    NASA Astrophysics Data System (ADS)

    Ullah, Ramzan; Zheng, Yuxiang

    2016-03-01

    Raman spectra (95 - 3000 cm-1) of 'Bisphenol A' are presented. Absorption peaks have been assigned by Density Functional Theory (DFT) with B3LYP 6 - 311 ++ G (3df, 3pd) and wB97XD 6 - 311 ++ G (3df, 3pd). B3LYP 6 - 311 ++ G (3df, 3pd) gives frequencies which are nearer to experimental frequencies than wB97XD 6 - 311 ++ G (3df, 3pd) which involves empirical dispersion. Scale factor for wB97XD 6 - 311 ++ G (3df, 3pd) is found out to be 0.95008 by least squares fit.

  6. Raman spectroscopy in head and neck cancer

    PubMed Central

    2010-01-01

    In recent years there has been much interest in the use of optical diagnostics in cancer detection. Early diagnosis of cancer affords early intervention and greatest chance of cure. Raman spectroscopy is based on the interaction of photons with the target material producing a highly detailed biochemical 'fingerprint' of the sample. It can be appreciated that such a sensitive biochemical detection system could confer diagnostic benefit in a clinical setting. Raman has been used successfully in key health areas such as cardiovascular diseases, and dental care but there is a paucity of literature on Raman spectroscopy in Head and Neck cancer. Following the introduction of health care targets for cancer, and with an ever-aging population the need for rapid cancer detection has never been greater. Raman spectroscopy could confer great patient benefit with early, rapid and accurate diagnosis. This technique is almost labour free without the need for sample preparation. It could reduce the need for whole pathological specimen examination, in theatre it could help to determine margin status, and finally peripheral blood diagnosis may be an achievable target. PMID:20923567

  7. Raman Spectroscopy of Soft Musculoskeletal Tissues

    PubMed Central

    Esmonde-White, Karen

    2015-01-01

    Tendon, ligament, and joint tissues are important in maintaining daily function. They can be affected by disease, age, and injury. Slow tissue turnover, hierarchical structure and function, and nonlinear mechanical properties present challenges to diagnosing and treating soft musculoskeletal tissues. Understanding these tissues in health, disease, and injury is important to improving pharmacologic and surgical repair outcomes. Raman spectroscopy is an important tool in the examination of soft musculoskeletal tissues. This article highlights exciting basic science and clinical/translational Raman studies of cartilage, tendon, and ligament. PMID:25286106

  8. Candida parapsilosis Biofilm Identification by Raman Spectroscopy

    PubMed Central

    Samek, Ota; Mlynariková, Katarina; Bernatová, Silvie; Ježek, Jan; Krzyžánek, Vladislav; Šiler, Martin; Zemánek, Pavel; Růžička, Filip; Holá, Veronika; Mahelová, Martina

    2014-01-01

    Colonies of Candida parapsilosis on culture plates were probed directly in situ using Raman spectroscopy for rapid identification of specific strains separated by a given time intervals (up to months apart). To classify the Raman spectra, data analysis was performed using the approach of principal component analysis (PCA). The analysis of the data sets generated during the scans of individual colonies reveals that despite the inhomogeneity of the biological samples unambiguous associations to individual strains (two biofilm-positive and two biofilm-negative) could be made. PMID:25535081

  9. Candida parapsilosis biofilm identification by Raman spectroscopy.

    PubMed

    Samek, Ota; Mlynariková, Katarina; Bernatová, Silvie; Ježek, Jan; Krzyžánek, Vladislav; Šiler, Martin; Zemánek, Pavel; Růžička, Filip; Holá, Veronika; Mahelová, Martina

    2014-01-01

    Colonies of Candida parapsilosis on culture plates were probed directly in situ using Raman spectroscopy for rapid identification of specific strains separated by a given time intervals (up to months apart). To classify the Raman spectra, data analysis was performed using the approach of principal component analysis (PCA). The analysis of the data sets generated during the scans of individual colonies reveals that despite the inhomogeneity of the biological samples unambiguous associations to individual strains (two biofilm-positive and two biofilm-negative) could be made. PMID:25535081

  10. Raman spectroscopy: Caution when interpreting organic carbon from oxidising environments

    NASA Astrophysics Data System (ADS)

    Brolly, Connor; Parnell, John; Bowden, Stephen

    2016-02-01

    Oxidation on Mars is primarily caused by the high influx of cosmic and solar radiation which interacts with the Martian surface. The evidence of this can be seen in the ubiquitous red colouration of the Martian sediment. This radiation will destroy most signals of life in the top few metres of the Martian surface. If organic carbon (one of the building blocks of life) is present within the accessible Martian sediments, it is very likely that it will have experienced some oxidation. ESA's ExoMars mission set to fly in 2018, has on board a miniaturised Raman spectrometer. As Raman spectroscopy is sensitive to carbonaceous material and will be primarily used to characterise organics, it is essential that the effect oxidation has on the Raman carbon signal is assessed. Oxidised carbonaceous shales were analysed using Raman spectroscopy to assess this issue. Results show that haematite has a band which occurs in the same frequency as the carbon D band, which cannot be distinguished from each other. This can lead to a misidentification of the carbon D band and a misinterpretation of the carbon order. Consequently, caution must be taken when applying Raman spectroscopy for organic carbon analysis in oxidised terrestrial and extraterrestrial environments, including on Mars.

  11. Two-dimensional low resolution Raman spectroscopy applied to fast discrimination of microorganisms that cause pharyngitis: A whole-organism fingerprinting approach

    NASA Astrophysics Data System (ADS)

    Mello, Cesar; Severi, Eza; Coelho, Lucinda; Marangoni, Antônio; Dezuane, Christiane; Ricci, Emiliane; Ribeiro, Diórginis; Poppi, Ronei Jesus

    2008-07-01

    The discrimination of the bacteria that cause pharyngitis through classical-microbiological methods is very efficient in the great majority of the cases. However, the high cost of chemicals and the time spent for such identifications, about four days, could generate serious consequences for the patients. Thus, the search for low cost spectroscopic methods which would allow a fast and reagentless discrimination of these microorganisms is extremely relevant. In this work, the main microorganisms that cause pharyngitis: S. aureus, S. pyogenes and Neisseria gonorrhoeae were studied. For each of the microorganisms 60 different dispersions were prepared using physiological solution as solvent and its Raman spectra were recorded. The 1D spectra obtained were similar, making it very difficult to differentiate the microorganisms. However, applying the 2D correlation method, it was possible to identify the microorganisms evaluated using the synchronous spectrum as "whole-organism fingerprinting" in a reduced time interval (˜10 h).

  12. Detection and Quantitative Analysis of Chemical Species in Hanford Tank Materials Using Raman Spectroscopy Technology: FY94Florida State University Raman Spectroscopy Report

    SciTech Connect

    Reich, F.R.

    1997-08-11

    This report provides a summary of work completed in FY-94 by FSU to develop and investigate the feasibility of using Raman spectroscopy with Hanford tank waste materials. Raman performance impacts from sample morphology, including the effects of absorption, particle size, density, color and refractive index, are discussed. An algorithm for relative species concentration measurement from Raman data is presented. An Algorithm for applying Raman to tank waste core screening is presented and discussed. A library of absorption and Raman spectra are presented that support this work.

  13. Drug Stability Analysis by Raman Spectroscopy

    PubMed Central

    Shende, Chetan; Smith, Wayne; Brouillette, Carl; Farquharson, Stuart

    2014-01-01

    Pharmaceutical drugs are available to astronauts to help them overcome the deleterious effects of weightlessness, sickness and injuries. Unfortunately, recent studies have shown that some of the drugs currently used may degrade more rapidly in space, losing their potency before their expiration dates. To complicate matters, the degradation products of some drugs can be toxic. Here, we present a preliminary investigation of the ability of Raman spectroscopy to quantify mixtures of four drugs; acetaminophen, azithromycin, epinephrine, and lidocaine, with their primary degradation products. The Raman spectra for the mixtures were replicated by adding the pure spectra of the drug and its degradant to determine the relative percent contributions using classical least squares. This multivariate approach allowed determining concentrations in ~10 min with a limit of detection of ~4% of the degradant. These results suggest that a Raman analyzer could be used to assess drug potency, nondestructively, at the time of use to ensure crewmember safety. PMID:25533308

  14. Characterization of diatomaceous silica by Raman spectroscopy.

    PubMed

    Yuan, P; He, H P; Wu, D Q; Wang, D Q; Chen, L J

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm(-1) are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO)3-ring breathing mode of D2-line and the O3SiOH tetrahedral vibration mode of D1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO)3-ring, the sample must be heated between 250 and 450 degrees C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D1 nor D2 band is detected in previous reports. PMID:15350933

  15. Characterization of diatomaceous silica by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yuan, P.; He, H. P.; Wu, D. Q.; Wang, D. Q.; Chen, L. J.

    2004-10-01

    The network characteristic of a selection of diatomaceous silica derived from China has been investigated using Raman spectroscopy. Before any thermal treatment of the sample, two prominent bands of 607 and circa 493 cm -1 are resolved in the Raman spectra of diatomaceous silica, corresponding to the (SiO) 3-ring breathing mode of D 2-line and the O 3SiOH tetrahedral vibration mode of D 1-line, respectively. This is more similar to the pyrogenic silica rather than the silica gel. For the latter, to obtain a (SiO) 3-ring, the sample must be heated between 250 and 450 °C. Significant difference is also found between the diatomaceous silica and other natural silicas, e.g. in the Raman spectra of sedimentary and volcanic opals, neither D 1 nor D 2 band is detected in previous reports.

  16. Remote adjustable focus Raman spectroscopy probe

    DOEpatents

    Schmucker, John E.; Blasi, Raymond J.; Archer, William B.

    1999-01-01

    A remote adjustable focus Raman spectroscopy probe allows for analyzing Raman scattered light from a point of interest external probe. An environmental barrier including at least one window separates the probe from the point of interest. An optical tube is disposed adjacent to the environmental barrier and includes a long working length compound lens objective next to the window. A beam splitter and a mirror are at the other end. A mechanical means is used to translated the prove body in the X, Y, and Z directions resulting in a variable focus optical apparatus. Laser light is reflected by the beam splitter and directed toward the compound lens objective, then through the window and focused on the point of interest. Raman scattered light is then collected by the compound lens objective and directed through the beam splitter to a mirror. A device for analyzing the light, such as a monochrometer, is coupled to the mirror.

  17. Drug stability analysis by Raman spectroscopy.

    PubMed

    Shende, Chetan; Smith, Wayne; Brouillette, Carl; Farquharson, Stuart

    2014-01-01

    Pharmaceutical drugs are available to astronauts to help them overcome the deleterious effects of weightlessness, sickness and injuries. Unfortunately, recent studies have shown that some of the drugs currently used may degrade more rapidly in space, losing their potency before their expiration dates. To complicate matters, the degradation products of some drugs can be toxic. Here, we present a preliminary investigation of the ability of Raman spectroscopy to quantify mixtures of four drugs; acetaminophen, azithromycin, epinephrine, and lidocaine, with their primary degradation products. The Raman spectra for the mixtures were replicated by adding the pure spectra of the drug and its degradant to determine the relative percent contributions using classical least squares. This multivariate approach allowed determining concentrations in ~10 min with a limit of detection of ~4% of the degradant. These results suggest that a Raman analyzer could be used to assess drug potency, nondestructively, at the time of use to ensure crewmember safety. PMID:25533308

  18. Detecting changes during pregnancy with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Vargis, Elizabeth; Robertson, Kesha; Al-Hendy, Ayman; Reese, Jeff; Mahadevan-Jansen, Anita

    2010-02-01

    Preterm labor is the second leading cause of neonatal mortality and leads to a myriad of complications like delayed development and cerebral palsy. Currently, there is no way to accurately predict preterm labor, making its prevention and treatment virtually impossible. While there are some at-risk patients, over half of all preterm births do not fall into any high-risk category. This study seeks to predict and prevent preterm labor by using Raman spectroscopy to detect changes in the cervix during pregnancy. Since Raman spectroscopy has been used to detect cancers in vivo in organs like the cervix and skin, it follows that spectra will change over the course of pregnancy. Previous studies have shown that fluorescence decreased during pregnancy and increased during post-partum exams to pre-pregnancy levels. We believe significant changes will occur in the Raman spectra obtained during the course of pregnancy. In this study, Raman spectra from the cervix of pregnant mice and women will be acquired. Specific changes that occur due to cervical softening or changes in hormonal levels will be observed to understand the likelihood that a female mouse or a woman will enter labor.

  19. Raman spectroscopy for analysis of thorium compounds

    NASA Astrophysics Data System (ADS)

    Su, Yin-Fong; Johnson, Timothy J.; Olsen, Khris B.

    2016-05-01

    The thorium fuel cycle is an alternative to the uranium fuel cycle in that when 232Th is irradiated with neutrons it is converted to 233U, another fissile isotope. There are several chemical forms of thorium which are used in the Th fuel cycle. Recently, Raman spectroscopy has become a very portable and facile analytical technique useful for many applications, including e.g. determining the chemical composition of different materials such as for thorium compounds. The technique continues to improve with the development of ever-more sensitive instrumentation and better software. Using a laboratory Fourier-transform (FT)-Raman spectrometer with a 785 nm wavelength laser, we were able to obtain Raman spectra from a series of thorium-bearing compounds of unknown origin. These spectra were compared to the spectra of in-stock-laboratory thorium compounds including e.g. ThO2, ThF4, Th(CO3)2 and Th(C2O4)2. The unknown spectra showed very good agreement to the known standards, demonstrating the applicability of Raman spectroscopy for detection and identification of these nuclear materials.

  20. Raman spectroscopy of ion-implanted silicon

    SciTech Connect

    Tuschel, D.D.; Lavine, J.P.

    1997-11-01

    Raman spectroscopy is used to characterize silicon implanted with boron at a dose of 10{sup 14}/cm{sup 2} or less and thermally annealed. The Raman scattering strengths and band shapes of the first-order optical mode at 520 cm{sup {minus}1} and of the second-order phonon modes are investigated to determine which modes are sensitive to the boron implant. The as-implanted samples show diminishing Raman scattering strength as the boron dose increases when the incident laser beam is 60{degree} with respect to the sample normal. Thermal annealing restores some of the Raman scattering strength. Three excitation wavelengths are used and the shortest, 457.9 nm, yields the greatest spectral differences from unimplanted silicon. The backscattering geometry shows a variety of changes in the Raman spectrum upon boron implantation. These involve band shifts of the first-order optical mode, bandwidth variations of the first-order optical mode, and the intensity of the second-order mode at 620 cm{sup {minus}1}.

  1. Toward improving fine needle aspiration cytology by applying Raman microspectroscopy

    NASA Astrophysics Data System (ADS)

    Becker-Putsche, Melanie; Bocklitz, Thomas; Clement, Joachim; Rösch, Petra; Popp, Jürgen

    2013-04-01

    Medical diagnosis of biopsies performed by fine needle aspiration has to be very reliable. Therefore, pathologists/cytologists need additional biochemical information on single cancer cells for an accurate diagnosis. Accordingly, we applied three different classification models for discriminating various features of six breast cancer cell lines by analyzing Raman microspectroscopic data. The statistical evaluations are implemented by linear discriminant analysis (LDA) and support vector machines (SVM). For the first model, a total of 61,580 Raman spectra from 110 single cells are discriminated at the cell-line level with an accuracy of 99.52% using an SVM. The LDA classification based on Raman data achieved an accuracy of 94.04% by discriminating cell lines by their origin (solid tumor versus pleural effusion). In the third model, Raman cell spectra are classified by their cancer subtypes. LDA results show an accuracy of 97.45% and specificities of 97.78%, 99.11%, and 98.97% for the subtypes basal-like, HER2+/ER-, and luminal, respectively. These subtypes are confirmed by gene expression patterns, which are important prognostic features in diagnosis. This work shows the applicability of Raman spectroscopy and statistical data handling in analyzing cancer-relevant biochemical information for advanced medical diagnosis on the single-cell level.

  2. Raman Spectroscopy of Irradiated Tissue Samples

    NASA Astrophysics Data System (ADS)

    Alexa, P.; Synytsya, A.; Volka, K.; de Boer, J.; Besserer, J.; Froschauer, S.; Loewe, M.; Moosburger, M.; Würkner, M.

    2003-06-01

    Tissue samples (skin of mice, normal and tumor, skin of a woman, normal and tumor) were irradiated by protons from the Munich tandem accelerator. The samples were analysed using Raman spectroscopy at the Institute of Chemical Technology in Prague by measuring the intensity of signals sensitive to radiation damage. Effects depending on the delivered dose were found. Proton-irradiation effects are then compared to those of gamma-irradiation.

  3. Raman and photothermal spectroscopies for explosive detection

    NASA Astrophysics Data System (ADS)

    Finot, Eric; Brulé, Thibault; Rai, Padmnabh; Griffart, Aurélien; Bouhélier, Alexandre; Thundat, Thomas

    2013-06-01

    Detection of explosive residues using portable devices for locating landmine and terrorist weapons must sat- isfy the application criteria of high reproducibility, specificity, sensitivity and fast response time. Vibrational spectroscopies such as Raman and infrared spectroscopies have demonstrated their potential to distinguish the members of the chemical family of more than 30 explosive materials. The characteristic chemical fingerprints in the spectra of these explosives stem from the unique bond structure of each compound. However, these spectroscopies, developed in the early sixties, suffer from a poor sensitivity. On the contrary, MEMS-based chemical sensors have shown to have very high sensitivity lowering the detection limit down to less than 1 picogram, (namely 10 part per trillion) using sensor platforms based on microcantilevers, plasmonics, or surface acoustic waves. The minimum amount of molecules that can be detected depends actually on the transducer size. The selectivity in MEMS sensors is usually realized using chemical modification of the active surface. However, the lack of sufficiently selective receptors that can be immobilized on MEMS sensors remains one of the most critical issues. Microcantilever based sensors offer an excellent opportunity to combine both the infrared photothermal spectroscopy in their static mode and the unique mass sensitivity in their dynamic mode. Optical sensors based on localized plasmon resonance can also take up the challenge of addressing the selectivity by monitoring the Surface Enhanced Raman spectrum down to few molecules. The operating conditions of these promising localized spectroscopies will be discussed in terms of reliability, compactness, data analysis and potential for mass deployment.

  4. The Impact of Array Detectors on Raman Spectroscopy

    ERIC Educational Resources Information Center

    Denson, Stephen C.; Pommier, Carolyn J. S.; Denton, M. Bonner

    2007-01-01

    The impact of array detectors in the field of Raman spectroscopy and all low-light-level spectroscopic techniques is examined. The high sensitivity of array detectors has allowed Raman spectroscopy to be used to detect compounds at part per million concentrations and to perform Raman analyses at advantageous wavelengths.

  5. Raman Spectroscopy: Incorporating the Chemical Dimension into Dermatological Diagnosis

    PubMed Central

    Sharma, Amit; Sharma, Shruti; Zarrow, Anna; Schwartz, Robert A; Lambert, W Clark

    2016-01-01

    Raman spectroscopy provides chemical analysis of tissue in vivo. By measuring the inelastic interactions of light with matter, Raman spectroscopy can determine the chemical composition of a sample. Diseases that are visually difficult to visually distinguish can be delineated based on differences in chemical composition of the affected tissue. Raman spectroscopy has successfully found spectroscopic signatures for skin cancers and differentiated those of benign skin growths. With current and on-going advances in optics and computing, inexpensive and effective Raman systems may soon be available for clinical use. Raman spectroscopy provides direct analyses of skin lesions, thereby improving both disease diagnosis and management. PMID:26955087

  6. [Laser Raman Spectroscopy and Its Application in Gas Hydrate Studies].

    PubMed

    Fu, Juan; Wu, Neng-you; Lu, Hai-long; Wu, Dai-dai; Su, Qiu-cheng

    2015-11-01

    Gas hydrates are important potential energy resources. Microstructural characterization of gas hydrate can provide information to study the mechanism of gas hydrate formation and to support the exploitation and application of gas hydrate technology. This article systemly introduces the basic principle of laser Raman spectroscopy and summarizes its application in gas hydrate studies. Based on Raman results, not only can the information about gas composition and structural type be deduced, but also the occupancies of large and small cages and even hydration number can be calculated from the relative intensities of Raman peaks. By using the in-situ analytical technology, laser Raman specstropy can be applied to characterize the formation and decomposition processes of gas hydrate at microscale, for example the enclathration and leaving of gas molecules into/from its cages, to monitor the changes in gas concentration and gas solubility during hydrate formation and decomposition, and to identify phase changes in the study system. Laser Raman in-situ analytical technology has also been used in determination of hydrate structure and understanding its changing process under the conditions of ultra high pressure. Deep-sea in-situ Raman spectrometer can be employed for the in-situ analysis of the structures of natural gas hydrate and their formation environment. Raman imaging technology can be applied to specify the characteristics of crystallization and gas distribution over hydrate surface. With the development of laser Raman technology and its combination with other instruments, it will become more powerful and play a more significant role in the microscopic study of gas hydrate. PMID:26978895

  7. Distinguishing Cancerous Liver Cells Using Surface-Enhanced Raman Spectroscopy.

    PubMed

    Huang, Jing; Liu, Shupeng; Chen, Zhenyi; Chen, Na; Pang, Fufei; Wang, Tingyun

    2016-02-01

    Raman spectroscopy has been widely used in biomedical research and clinical diagnostics. It possesses great potential for the analysis of biochemical processes in cell studies. In this article, the surface-enhanced Raman spectroscopy (SERS) of normal and cancerous liver cells incubated with SERS active substrates (gold nanoparticle) was measured using confocal Raman microspectroscopy technology. The chemical components of the cells were analyzed through statistical methods for the SERS spectrum. Both the relative intensity ratio and principal component analysis (PCA) were used for distinguishing the normal liver cells (QSG-7701) from the hepatoma cells (SMMC-7721). The relative intensity ratio of the Raman spectra peaks such as I937/I1209, I1276/I1308, I1342/I1375, and I1402/I1435 was set as the judge boundary, and the sensitivity and the specificity using PCA method were calculated. The results indicated that the surface-enhanced Raman spectrum could provide the chemical information for distinguishing the normal cells from the cancerous liver cells and demonstrated that SERS technology possessed the possible applied potential for the diagnosis of liver cancer. PMID:25432931

  8. Standoff detection of explosive molecules using nanosecond gated Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chung, Jin Hyuk; Cho, Soo Gyeong

    2013-06-01

    Recently, improvised explosive device (IED) has been a serious threat for many countries. One of the approaches to alleviate this threat is standoff detection of explosive molecules used in IEDs. Raman spectroscopy is a prospective method among many technologies under research to achieve this goal. It provides unique information of the target materials, through which the ingredients used in IEDs can be analyzed and identified. The main problem of standoff Raman spectroscopic detection is the large background noise hindering weak Raman signals from the target samples. Typical background noise comes from both ambient fluorescent lights indoor and sunlight outdoor whose intensities are usually much larger than that of Raman scattering from the sample. Under the proper condition using pulse laser and ICCD camera with nanosecond pulse width and gating technology, we succeed to separate and remove these background noises from Raman signals. For this experiment, we build an optical system for standoff detection of explosive molecules. We use 532 nm, 10 Hz, Q-switching Nd:YAG laser as light source, and ICCD camera triggered by laser Qswitching time with proper gate delay regarding the flight time of Raman from target materials. Our detection system is successfully applied to detect and identify more than 20 ingredients of IEDs including TNT, RDX, and HMX which are located 10 to 54 meters away from the system.

  9. [Raman spectroscopy applied to analytical quality control of injectable drugs: analytical evaluation and comparative economic versus HPLC and UV / visible-FTIR].

    PubMed

    Bourget, P; Amin, A; Vidal, F; Merlette, C; Troude, P; Corriol, O

    2013-09-01

    In France, central IV admixture of chemotherapy (CT) treatments at the hospital is now required by law. We have previously shown that the shaping of Therapeutic Objects (TOs) could profit from an Analytical Quality Assurance (AQA), closely linked to the batch release, for the three key parameters: identity, purity, and initial concentration of the compound of interest. In the course of recent and diversified works, we showed the technical superiority of non-intrusive Raman Spectroscopy (RS) vs. any other analytical option and, especially for both HPLC and vibrational method using a UV/visible-FTIR coupling. An interconnected qualitative and economic assessment strongly helps to enrich these relevant works. The study compares in operational situation, the performance of three analytical methods used for the AQC of TOs. We used: a) a set of evaluation criteria, b) the depreciation tables of the machinery, c) the cost of disposables, d) the weight of equipment and technical installations, e) the basic accounting unit (unit of work) and its composite costs (Euros), which vary according to the technical options, the weight of both human resources and disposables; finally, different combinations are described. So, the unit of work can take 12 different values between 1 and 5.5 Euros, and we provide various recommendations. A qualitative evaluation grid constantly places the SR technology as superior or equal to the 2 other techniques currently available. Our results demonstrated: a) the major interest of the non-intrusive AQC performed by RS, especially when it is not possible to analyze a TO with existing methods e.g. elastomeric portable pumps, and b) the high potential for this technique to be a strong contributor to the security of the medication circuit, and to fight the iatrogenic effects of drugs especially in the hospital. It also contributes to the protection of all actors in healthcare and of their working environment. PMID:24804411

  10. Raman spectroscopy of C-irradiated graphite

    SciTech Connect

    Hembree, D.M. Jr.; Pedraza, D.F.; Romanoski, G.R.; Withrow, S.P.; Annis, B.K.

    1994-09-01

    Highly oriented pyrolytic graphite samples were irradiated with C{sup +} ions at 35 keV in a direction normal to the basal plane and subsequently annealed up to 1373 K. Substantial surface topography changes were observed at fluences of 5 {times} 10{sup 18} ions/m{sup 2} and higher using scanning electron and atomic force microscopies. Intricate networks of surface cracks and ridges developed after high dose implantation. A systematic study of the irradiation effects was conducted using Raman spectroscopy. Microstructural changes in irradiated regions were first detected at a dose of 1 {times} 10{sup 17} ions/m{sup 2} through the appearance of the Raman D-line at {approx}1360 cm{sup {minus}1}. The intensity of this line increases while that of the Raman G-line at 1580 cm{sup {minus}1} decreases as the irradiation dose is increased or the irradiation temperature is decreased. After irradiation at 280K to a fluence of 5 {times} 10{sup 19} ions/m{sup 2} or higher the first order spectrum exhibits one single line at a wavelength intermediate between the D- and G-lines. Damage recovery upon thermal annealing depends not only on the initial damage state but also on the annealing temperature sequence. Samples irradiated to a damage level where two distinct Raman peaks are no longer resolvable exhibited upon direct annealing at a high temperature two distinct Raman lines. By contrast, pre-annealing these highly irradiated specimens at lower temperatures produced less pronounced changes in the Raman spectra. Pre-annealing appears to stabilize damage structures that are more resistant to high-temperature annealing than those induced by irradiation.

  11. Raman spectroscopy for cytopathology of exfoliated cervical cells.

    PubMed

    Ramos, I R; Meade, A D; Ibrahim, O; Byrne, H J; McMenamin, M; McKenna, M; Malkin, A; Lyng, F M

    2016-06-23

    Cervical cancer is the fourth most common cancer affecting women worldwide but mortality can be decreased by early detection of pre-malignant lesions. The Pap smear test is the most commonly used method in cervical cancer screening programmes. Although specificity is high for this test, it is widely acknowledged that sensitivity can be poor mainly due to the subjective nature of the test. There is a need for new objective tests for the early detection of pre-malignant cervical lesions. Over the past two decades, Raman spectroscopy has emerged as a promising new technology for cancer screening and diagnosis. The aim of this study was to evaluate the potential of Raman spectroscopy for cervical cancer screening using both Cervical Intraepithelial Neoplasia (CIN) and Squamous Intraepithelial Lesion (SIL) classification terminology. ThinPrep® Pap samples were recruited from a cervical screening population. Raman spectra were recorded from single cell nuclei and subjected to multivariate statistical analysis. Normal and abnormal ThinPrep® samples were discriminated based on the biochemical fingerprint of the cells using Principal Component Analysis (PCA). Principal Component Analysis - Linear Discriminant Analysis (PCA-LDA) was employed to build classification models based on either CIN or SIL terminology. This study has shown that Raman spectroscopy can be successfully applied to the study of routine cervical cytology samples from a cervical screening programme and that the use of CIN terminology resulted in improved sensitivity for high grade cases. PMID:27032537

  12. Raman spectroscopy for diagnosis of glioblastoma multiforme

    NASA Astrophysics Data System (ADS)

    Clary, Candace Elise

    Glioblastoma multiforme (GBM), the most common and most fatal malignant brain tumor, is highly infiltrative and incurable. Although improved prognosis has been demonstrated by surgically resecting the bulk tumor, a lack of clear borders at the tumor margins complicates the selection decision during surgery. This dissertation investigates the potential of Raman spectroscopy for distinguishing between normal and malignant brain tissue and sets the groundwork for a surgical diagnostic guide for resection of gross malignant gliomas. These studies revealed that Raman spectroscopy was capable of discriminating between normal scid mouse brain tissue and human xenograft tumors induced in those mice. The spectra of normal and malignant tissue were normalized by dividing by the respective magnitudes of the peaks near 1440 cm -1. Spectral differences include the shape of the broad peaks near 1440 cm-1 and 1660 cm-1 and the relative magnitudes of the peaks at 1264 cm-1, 1287 cm-1, 1297 cm-1, 1556 cm -1, 1586 cm-1, 1614 cm-1, and 1683 cm-1. From these studies emerged questions regarding how to objectively normalize and compare spectra for future automation. Some differences in the Raman spectra were shown to be inherent in the disease states of the cells themselves via differences in the Raman spectra of normal human astrocytes in culture and cultured cells derived from GBM tumors. The spectra of astrocytes and glioma cells were normalized by dividing by the respective magnitudes of the peaks near 1450 cm-1. The differences between the Raman spectra of normal and transformed cells include the ratio of the 1450 cm-1/1650 cm-1 peaks and the relative magnitudes of the peaks at 1181 cm-1, 1191 cm-1, 1225 cm-1, 1263 cm -1, 1300 cm-1, 1336 cm-1, 1477 cm-1, 1494 cm-1, and 1695 cm -1. Previous Raman spectroscopic studies of biological cells have shown that the magnitude of the Raman signal decreases over time, indicating sample damage. Cells exposed to laser excitation at similar power

  13. Electronic resonances in broadband stimulated Raman spectroscopy

    PubMed Central

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process. PMID:26728791

  14. Electronic resonances in broadband stimulated Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Batignani, G.; Pontecorvo, E.; Giovannetti, G.; Ferrante, C.; Fumero, G.; Scopigno, T.

    2016-01-01

    Spontaneous Raman spectroscopy is a formidable tool to probe molecular vibrations. Under electronic resonance conditions, the cross section can be selectively enhanced enabling structural sensitivity to specific chromophores and reaction centers. The addition of an ultrashort, broadband femtosecond pulse to the excitation field allows for coherent stimulation of diverse molecular vibrations. Within such a scheme, vibrational spectra are engraved onto a highly directional field, and can be heterodyne detected overwhelming fluorescence and other incoherent signals. At variance with spontaneous resonance Raman, however, interpreting the spectral information is not straightforward, due to the manifold of field interactions concurring to the third order nonlinear response. Taking as an example vibrational spectra of heme proteins excited in the Soret band, we introduce a general approach to extract the stimulated Raman excitation profiles from complex spectral lineshapes. Specifically, by a quantum treatment of the matter through density matrix description of the third order nonlinear polarization, we identify the contributions which generate the Raman bands, by taking into account for the cross section of each process.

  15. Spectral variable selection for partial least squares calibration applied to authentication and quantification of extra virgin olive oils using Fourier transform Raman spectroscopy.

    PubMed

    Heise, H Michael; Damm, Uwe; Lampen, Peter; Davies, Antony N; McIntyre, Peter S

    2005-10-01

    The limits of quantitative multivariate assays for the analysis of extra virgin olive oil samples from various Greek sites adulterated by sunflower oil have been evaluated based on their Fourier transform (FT) Raman spectra. Different strategies for wavelength selection were tested for calculating optimal partial least squares (PLS) models. Compared to the full spectrum methods previously applied, the optimum standard error of prediction (SEP) for the sunflower oil concentrations in spiked olive oil samples could be significantly reduced. One efficient approach (PMMS, pair-wise minima and maxima selection) used a special variable selection strategy based on a pair-wise consideration of significant respective minima and maxima of PLS regression vectors, calculated for broad spectral intervals and a low number of PLS factors. PMMS provided robust calibration models with a small number of variables. On the other hand, the Tabu search strategy recently published (search process guided by restrictions leading to Tabu list) achieved lower SEP values but at the cost of extensive computing time when searching for a global minimum and less robust calibration models. Robustness was tested by using packages of ten and twenty randomly selected samples within cross-validation for calculating independent prediction values. The best SEP values for a one year's harvest with a total number of 66 Cretian samples were obtained by such spectral variable optimized PLS calibration models using leave-20-out cross-validation (values between 0.5 and 0.7% by weight). For the more complex population of olive oil samples from all over Greece (total number of 92 samples), results were between 0.7 and 0.9% by weight with a cross-validation sample package size of 20. Notably, the calibration method with Tabu variable selection has been shown to be a valid chemometric approach by which a single model can be applied with a low SEP of 1.4% for olive oil samples across three different harvest years

  16. Noninvasive glucose sensing by transcutaneous Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Shih, Wei-Chuan; Bechtel, Kate L.; Rebec, Mihailo V.

    2015-05-01

    We present the development of a transcutaneous Raman spectroscopy system and analysis algorithm for noninvasive glucose sensing. The instrument and algorithm were tested in a preclinical study in which a dog model was used. To achieve a robust glucose test system, the blood levels were clamped for periods of up to 45 min. Glucose clamping and rise/fall patterns have been achieved by injecting glucose and insulin into the ear veins of the dog. Venous blood samples were drawn every 5 min and a plasma glucose concentration was obtained and used to maintain the clamps, to build the calibration model, and to evaluate the performance of the system. We evaluated the utility of the simultaneously acquired Raman spectra to be used to determine the plasma glucose values during the 8-h experiment. We obtained prediction errors in the range of ˜1.5-2 mM. These were in-line with a best-case theoretical estimate considering the limitations of the signal-to-noise ratio estimates. As expected, the transition regions of the clamp study produced larger predictive errors than the stable regions. This is related to the divergence of the interstitial fluid (ISF) and plasma glucose values during those periods. Two key contributors to error beside the ISF/plasma difference were photobleaching and detector drift. The study demonstrated the potential of Raman spectroscopy in noninvasive applications and provides areas where the technology can be improved in future studies.

  17. Noninvasive glucose sensing by transcutaneous Raman spectroscopy

    PubMed Central

    Shih, Wei-Chuan; Bechtel, Kate L.; Rebec, Mihailo V.

    2015-01-01

    Abstract. We present the development of a transcutaneous Raman spectroscopy system and analysis algorithm for noninvasive glucose sensing. The instrument and algorithm were tested in a preclinical study in which a dog model was used. To achieve a robust glucose test system, the blood levels were clamped for periods of up to 45 min. Glucose clamping and rise/fall patterns have been achieved by injecting glucose and insulin into the ear veins of the dog. Venous blood samples were drawn every 5 min and a plasma glucose concentration was obtained and used to maintain the clamps, to build the calibration model, and to evaluate the performance of the system. We evaluated the utility of the simultaneously acquired Raman spectra to be used to determine the plasma glucose values during the 8-h experiment. We obtained prediction errors in the range of ∼1.5−2  mM. These were in-line with a best-case theoretical estimate considering the limitations of the signal-to-noise ratio estimates. As expected, the transition regions of the clamp study produced larger predictive errors than the stable regions. This is related to the divergence of the interstitial fluid (ISF) and plasma glucose values during those periods. Two key contributors to error beside the ISF/plasma difference were photobleaching and detector drift. The study demonstrated the potential of Raman spectroscopy in noninvasive applications and provides areas where the technology can be improved in future studies. PMID:25688542

  18. Composition of Uranium Oxide Surface Layers Analyzed by m-Raman Spectroscopy

    SciTech Connect

    Siekhaus, W J

    2003-11-24

    Oxide thickness and composition averaged over a few square millimeter has been measured with nm thickness resolution by diffuse reflectance fourier transform infrared (FTIR) spectroscopy. {mu}-Raman spectroscopy has been done on powders and bulk samples in the past, and can now be done on surfaces layers with {micro}m lateral and depth resolution using con-focal microscopy. Here we apply con-focal-microscopy-based {mu}-Raman spectroscopy to a freshly polished/lightly oxidized and to heavily oxidized uranium to determine its sensitivity. The spectra show that {mu}-Raman spectroscopy does detect oxide thickness and oxide composition with high sensitivity.

  19. Surface-enhanced Raman spectroscopy of pterins

    NASA Astrophysics Data System (ADS)

    Smyth, Ciarán A.; Mirza, Inam; Lunney, James G.; McCabe, Eithne M.

    2012-03-01

    Raman spectroscopy is a useful technique in the identification and characterisation of compounds, but in terms of sensitivity its application is limited. With respect to this the discovery of the surface-enhanced Raman scattering (SERS) phenomenon has proved monumental, and much research has been carried out over the past 30 years developing the technique. Pterins are biological compounds that are found in nature in colour pigmentation and in mammalian metabolic pathways. Moreover, they have been identified in abnormal concentrations in cancer patients, suggesting potential applications in cancer diagnostics. SERS is an ideal technique to identify these compounds, and both nanoparticle suspensions and pulsed laser deposited nanoparticle substrates have been used to examine the spectra of xanthopterin, both in aqueous solution and in different pH environments.

  20. Lignin analysis by FT-Raman spectroscopy

    SciTech Connect

    Agarwal, U.P.; Obst, J.R.; Cannon, A.B.

    1996-10-01

    Traditional methods of lignin analysis, such as Klason (acid insoluble) lignin determinations, give satisfactory results, are widely accepted, and often are considered as standard analyses. However, the Klason lignin method is laborious and time consuming; it also requires a fairly large-amount of isolated analyte. FT-Raman spectroscopy offers an opportunity to simplify and speed up lignin analyses. FT-Raman data for a number of hardwoods (angiosperms) and softwoods (gymnosperms) are compared with data obtained using other analytical methods, including Klason lignin (with corrections for acid soluble lignin), acetyl bromide, and FT-IR determinations. In addition, 10 different specimens of Nothofagus dombeyii (chosen because of the widely varying syringyl:guaiacyl monomer compositions of their lignins) were also analyzed. Lignin monomer compositions were determined by thioacidolysis of by nitrobenzene oxidation.

  1. Simultaneous Conoscopic Holography and Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

    A new instrument was developed for chemical characterization of surfaces that combines the analytical power of Raman spectroscopy with the three-dimensional topographic information provided by conoscopic holography. The figure schematically depicts the proposed hybrid instrument. The output of the conoscopic holographic portion of the instrument is a topographical map of the surface; the output of the Raman portion of the instrument is hyperspectral Raman data, from which the chemical and/or biological composition of the surface would be deduced. By virtue of the basic principles of design and operation of the instrument, the hyperspectral image data would be inherently spatially registered with the topographical data. In conoscopic holography, the object and reference beams of classical holography are replaced by the ordinary and extraordinary components generated by a single beam traveling through a birefringent, uniaxial crystal. In the basic conoscopic configuration, a laser light is projected onto a specimen and the resulting illuminated spot becomes a point source of diffuse light that propagates in every direction. The laser beam is rasterscanned in two dimensions (x and y) perpendicular to the beam axis (z), and at each x,y location, the pattern of interference between the ordinary and extraordinary rays is recorded. The recorded interferogram constitutes the conoscopic hologram. Of particular significance for the proposed instrument is that the conoscopic hologram contains information on the z coordinate (height) of the illuminated surface spot. Hence, a topographical map of the specimen is constructed point-by-point by rastering the laser beam in the x and y directions and correlating the x and y coordinates with the z information obtained from the interferograms. Conoscopic imaging is an established method, and conoscopic laboratory instruments for surface metrology are commercially available. In Raman spectroscopy of a surface, one measures the spectrum

  2. Characterization of Thalidomide using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Cipriani, Penelope; Smith, Candace Y.

    2008-02-01

    Thalidomide is a potent anticancer therapeutic drug whose mechanism of action has not yet been elucidated. In this report, experimental Raman spectroscopy is used to determine and characterize the vibrational frequencies of the drug. These normal modes are then compared to their quantum mechanical counterparts, which have been computed using density functional theory. Upon analysis of the spectra, we found that there was a high level of agreement between the wavenumbers. As such, this spectroscopic technique may be a viable tool for examining the way in which this drug interacts with its target molecules.

  3. Raman spectroscopy of ball-milled TiO 2

    NASA Astrophysics Data System (ADS)

    Gajović, A.; Stubičar, M.; Ivanda, M.; Furić, K.

    2001-05-01

    Raman spectroscopy was applied to study structural and dimensional changes during high-energy ball milling of TiO 2 anatase. Milling was performed for up to 10 h using two different sets of grinding tools (wolfram carbide (WC) and agate). The diminution of the TiO 2 particle to nanometric size was monitoring by low-frequency Raman spectroscopy. The nanometric sizes were confirmed by transmission electron microscopy (TEM). After short milling time by WC the bands of high-pressure TiO 2 II phase (α-PbO 2 structure) were detected in Raman spectrum. Prolonged milling time was needed for transformation to rutil. When milling was performed by agate, the time necessary for both phase transitions was longer, presumably because of lower ball-to-powder weight ratio. The low-frequency Raman band of the prolonged milled samples was broad, which suggests the wide dispersion in nano-particle dimensions. The position of the low-frequency band in longer-milled samples indicated dimensions smaller than 20 nm, since the diameter of the particle is inversely proportional to the low-frequency mode of the spherical particles. These results were in agreement with the TEM results.

  4. Role of Raman spectroscopy and surface enhanced Raman spectroscopy in colorectal cancer

    PubMed Central

    Jenkins, Cerys A; Lewis, Paul D; Dunstan, Peter R; Harris, Dean A

    2016-01-01

    Colorectal cancer (CRC) is the fourth most common cancer in the United Kingdom and is the second largest cause of cancer related death in the United Kingdom after lung cancer. Currently in the United Kingdom there is not a diagnostic test that has sufficient differentiation between patients with cancer and those without cancer so the current referral system relies on symptomatic presentation in a primary care setting. Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) are forms of vibrational spectroscopy that offer a non-destructive method to gain molecular information about biological samples. The techniques offer a wide range of applications from in vivo or in vitro diagnostics using endoscopic probes, to the use of micro-spectrometers for analysis of biofluids. The techniques have the potential to detect molecular changes prior to any morphological changes occurring in the tissue and therefore could offer many possibilities to aid the detection of CRC. The purpose of this review is to look at the current state of diagnostic technology in the United Kingdom. The development of Raman spectroscopy and SERS in clinical applications relation for CRC will then be discussed. Finally, future areas of research of Raman/SERS as a clinical tool for the diagnosis of CRC are also discussed. PMID:27190582

  5. UTI diagnosis and antibiogram using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kastanos, Evdokia; Kyriakides, Alexandros; Hadjigeorgiou, Katerina; Pitris, Constantinos

    2009-07-01

    Urinary tract infection diagnosis and antibiogram require a 48 hour waiting period using conventional methods. This results in ineffective treatments, increased costs and most importantly in increased resistance to antibiotics. In this work, a novel method for classifying bacteria and determining their sensitivity to an antibiotic using Raman spectroscopy is described. Raman spectra of three species of gram negative Enterobacteria, most commonly responsible for urinary tract infections, were collected. The study included 25 samples each of E.coli, Klebsiella p. and Proteus spp. A novel algorithm based on spectral ratios followed by discriminant analysis resulted in classification with over 94% accuracy. Sensitivity and specificity for the three types of bacteria ranged from 88-100%. For the development of an antibiogram, bacterial samples were treated with the antibiotic ciprofloxacin to which they were all sensitive. Sensitivity to the antibiotic was evident after analysis of the Raman signatures of bacteria treated or not treated with this antibiotic as early as two hours after exposure. This technique can lead to the development of new technology for urinary tract infection diagnosis and antibiogram with same day results, bypassing urine cultures and avoiding all undesirable consequences of current practice.

  6. Disease recognition by infrared and Raman spectroscopy.

    PubMed

    Krafft, Christoph; Steiner, Gerald; Beleites, Claudia; Salzer, Reiner

    2009-02-01

    Infrared (IR) and Raman spectroscopy are emerging biophotonic tools to recognize various diseases. The current review gives an overview of the experimental techniques, data-classification algorithms and applications to assess soft tissues, hard tissues and body fluids. The methodology section presents the principles to combine vibrational spectroscopy with microscopy, lateral information and fiber-optic probes. A crucial step is the classification of spectral data by a variety of algorithms. We discuss unsupervised algorithms such as cluster analysis or principal component analysis and supervised algorithms such as linear discriminant analysis, soft independent modeling of class analogies, artificial neural networks support vector machines, Bayesian classification, partial least-squares regression and ensemble methods. The selected topics include tumors of epithelial tissue, brain tumors, prion diseases, bone diseases, atherosclerosis, kidney stones and gallstones, skin tumors, diabetes and osteoarthritis. PMID:19343682

  7. Coronagraphic Notch Filter for Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Cohen, David; Stirbl, Robert

    2004-01-01

    A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are

  8. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Tenne, Dmitri

    2007-03-01

    Conventional vibrational spectroscopies operating in visible and infrared range fail to measure the phonon spectra of nanoscale ferroelectric structures because of extremely weak signals and the overwhelming substrate contribution. In this talk, application of ultraviolet (UV) Raman spectroscopy for studies of lattice dynamics and ferroelectric phase transitions in nanoscale ferroelectrics will be presented. We demonstrate that UV Raman spectroscopy is an effective technique allowing the observation of phonons and determination of the ferroelectric phase transition temperature (Tc) in nanoscale ferroelectrics, specifically, BaTiO3/SrTiO3 superlattices having the ferroelectric BaTiO3 layers as thin as 1 unit cell, and single BaTiO3 layers as thin as 4 nm. BaTiO3/SrTiO3 superlattices and ultrathin BaTiO3 films studied were grown by molecular beam epitaxy on SrTiO3 as well as GdScO3 and DyScO3 substrates. Excellent epitaxial quality and atomically abrupt interfaces are evidenced by X-ray diffraction and high resolution transmission electron microscopy. UV Raman results show that one-unit-cell thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are ferroelectric with the Tc as high as 250 K, and induce the polarization in much thicker SrTiO3 layers adjacent to them. The Tc in superlattices was tuned by hundreds of degrees from ˜170 to 650 K by varying the thicknesses of BaTiO3 and SrTiO3 layers. Using scandate substrates enables growth of superlattices with systematically changed coherent strain, thus allowing studying the stress effect on the ferroelectric phase transitions. UV Raman data are supported by the thermodynamic calculations of polarization in superlattices as a function of temperature. The work was done in collaboration with A. Soukiassian, W. Tian, D.G. Schlom, Y.L. Li, L.-Q. Chen, X.X. Xi (Pennsylvania State University), A. Bruchhausen, A. Fainstein (Centro Atomico Bariloche & Instituto Balseiro, Argentina), R. S. Katiyar (University of Puerto Rico), A

  9. In vivo Raman spectroscopy of cervix cancers

    NASA Astrophysics Data System (ADS)

    Rubina, S.; Sathe, Priyanka; Dora, Tapas Kumar; Chopra, Supriya; Maheshwari, Amita; Krishna, C. Murali

    2014-03-01

    Cervix-cancer is the third most common female cancer worldwide. It is the leading cancer among Indian females with more than million new diagnosed cases and 50% mortality, annually. The high mortality rates can be attributed to late diagnosis. Efficacy of Raman spectroscopy in classification of normal and pathological conditions in cervix cancers on diverse populations has already been demonstrated. Our earlier ex vivo studies have shown the feasibility of classifying normal and cancer cervix tissues as well as responders/non-responders to Concurrent chemoradiotherapy (CCRT). The present study was carried out to explore feasibility of in vivo Raman spectroscopic methods in classifying normal and cancerous conditions in Indian population. A total of 182 normal and 132 tumor in vivo Raman spectra, from 63 subjects, were recorded using a fiberoptic probe coupled HE-785 spectrometer, under clinical supervision. Spectra were acquired for 5 s and averaged over 3 times at 80 mW laser power. Spectra of normal conditions suggest strong collagenous features and abundance of non-collagenous proteins and DNA in case of tumors. Preprocessed spectra were subjected to Principal Component-Linear Discrimination Analysis (PCLDA) followed by leave-one-out-cross-validation. Classification efficiency of ~96.7% and 100% for normal and cancerous conditions respectively, were observed. Findings of the study corroborates earlier studies and suggest applicability of Raman spectroscopic methods in combination with appropriate multivariate tool for objective, noninvasive and rapid diagnosis of cervical cancers in Indian population. In view of encouraging results, extensive validation studies will be undertaken to confirm the findings.

  10. Controlling protected designation of origin of wine by Raman spectroscopy.

    PubMed

    Mandrile, Luisa; Zeppa, Giuseppe; Giovannozzi, Andrea Mario; Rossi, Andrea Mario

    2016-11-15

    In this paper, a Fourier Transform Raman spectroscopy method, to authenticate the provenience of wine, for food traceability applications was developed. In particular, due to the specific chemical fingerprint of the Raman spectrum, it was possible to discriminate different wines produced in the Piedmont area (North West Italy) in accordance with i) grape varieties, ii) production area and iii) ageing time. In order to create a consistent training set, more than 300 samples from tens of different producers were analyzed, and a chemometric treatment of raw spectra was applied. A discriminant analysis method was employed in the classification procedures, providing a classification capability (percentage of correct answers) of 90% for validation of grape analysis and geographical area provenance, and a classification capability of 84% for ageing time classification. The present methodology was applied successfully to raw materials without any preliminary treatment of the sample, providing a response in a very short time. PMID:27283630

  11. Resonant Raman spectroscopy of twisted multilayer graphene.

    PubMed

    Wu, Jiang-Bin; Zhang, Xin; Ijäs, Mari; Han, Wen-Peng; Qiao, Xiao-Fen; Li, Xiao-Li; Jiang, De-Sheng; Ferrari, Andrea C; Tan, Ping-Heng

    2014-01-01

    Graphene and other two-dimensional crystals can be combined to form various hybrids and heterostructures, creating materials on demand with properties determined by the interlayer interaction. This is the case even for a single material, where multilayer stacks with different relative orientation have different optical and electronic properties. Probing and understanding the interface coupling is thus of primary importance for fundamental science and applications. Here we study twisted multilayer graphene flakes with multi-wavelength Raman spectroscopy. We find a significant intensity enhancement of the interlayer coupling modes (C peaks) due to resonance with new optically allowed electronic transitions, determined by the relative orientation of the layers. The interlayer coupling results in a Davydov splitting of the C peak in systems consisting of two equivalent graphene multilayers. This allows us to directly quantify the interlayer interaction, which is much smaller compared with Bernal-stacked interfaces. This paves the way to the use of Raman spectroscopy to uncover the interface coupling of two-dimensional hybrids and heterostructures. PMID:25382099

  12. Characterization and identification of contraband using UV resonant Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lacey, Richard J.; Hayward, Ian P.; Sands, H. S.; Batchelder, David N.

    1997-02-01

    A range of explosives and narcotics have been examined using Raman spectroscopy with 244 nm excitation. This wavelength of excitation eliminates the fluorescence problems associated with excitation at visible wavelengths. Comparison with spectra obtained using visible excitation reveals that resonance Raman scattering is occurring. This results in simplified spectra, and enhanced Raman scattering efficiencies.

  13. Infrared and NIR Raman spectroscopy in medical microbiology

    NASA Astrophysics Data System (ADS)

    Naumann, Dieter

    1998-04-01

    FTIR and FT-NIR Raman spectra of intact microbial cells are highly specific, fingerprint-like signatures which can be used to (i) discriminate between diverse microbial species and strains, (ii) detect in situ intracellular components or structures such as inclusion bodies, storage materials or endospores, (iii) detect and quantify metabolically released CO2 in response to various different substrate, and (iv) characterize growth-dependent phenomena and cell-drug interactions. The characteristic information is extracted from the spectral contours by applying resolution enhancement techniques, difference spectroscopy, and pattern recognition methods such as factor-, cluster-, linear discriminant analysis, and artificial neural networks. Particularly interesting applications arise by means of a light microscope coupled to the spectrometer. FTIR spectra of micro-colonies containing less than 103 cells can be obtained from colony replica by a stamping technique that transfers micro-colonies growing on culture plates to a special IR-sample holder. Using a computer controlled x, y- stage together with mapping and video techniques, the fundamental tasks of microbiological analysis, namely detection, enumeration, and differentiation of micro- organisms can be integrated in one single apparatus. FTIR and NIR-FT-Raman spectroscopy can also be used in tandem to characterize medically important microorganisms. Currently novel methodologies are tested to take advantage of the complementary information of IR and Raman spectra. Representative examples on medically important microorganisms will be given that highlight the new possibilities of vibrational spectroscopies.

  14. Combined fiber probe for fluorescence lifetime and Raman spectroscopy

    PubMed Central

    Dochow, Sebastian; Ma, Dinglong; Latka, Ines; Bocklitz, Thomas; Hartl, Brad; Bec, Julien; Fatakdawala, Hussain; Marple, Eric; Urmey, Kirk; Wachsmann-Hogiu, Sebastian; Schmitt, Michael; Marcu, Laura; Popp, Jürgen

    2016-01-01

    In this contribution we present a dual modality fiber optic probe combining fluorescence lifetime imaging (FLIm) and Raman spectroscopy for in vivo endoscopic applications. The presented multi-spectroscopy probe enables efficient excitation and collection of fluorescence lifetime signals for FLIm in the UV/visible wavelength region, as well as of Raman spectra in the near-IR for simultaneous Raman/FLIm imaging. The probe was characterized in terms of its lateral resolution and distance dependency of the Raman and FLIm signals. In addition, the feasibility of the probe for in vivo FLIm and Raman spectral characterization of tissue was demonstrated. PMID:26093843

  15. Determining the Authenticity of Gemstones Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Aponick, Aaron; Marchozzi, Emedio; Johnston, Cynthia R.; Wigal, Carl T.

    1998-04-01

    The benefits of laser spectroscopy in the undergraduate curriculum have been the focus of several recent articles in this journal. Raman spectroscopy has been of particular interest since the similarities of Raman to conventional infrared spectroscopy make the interpretation of spectral data well within undergraduate comprehension. In addition, the accessibility to this technology is now within the reach of most undergraduate institutions. This paper reports the development of an experiment using Raman spectroscopy which determines the authenticity of both diamonds and pearls. The resulting spectra provide an introduction to vibrational spectroscopy and can be used in a variety of laboratory courses ranging from introductory chemistry to instrumental analysis.

  16. Evaluation of thyroid tissue by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Teixeira, C. S. B.; Bitar, R. A.; Santos, A. B. O.; Kulcsar, M. A. V.; Friguglietti, C. U. M.; Martinho, H. S.; da Costa, R. B.; Martin, A. A.

    2010-02-01

    Thyroid gland is a small gland in the neck consisting of two lobes connected by an isthmus. Thyroid's main function is to produce the hormones thyroxine (T4), triiodothyronine (T3) and calcitonin. Thyroid disorders can disturb the production of these hormones, which will affect numerous processes within the body such as: regulating metabolism and increasing utilization of cholesterol, fats, proteins, and carbohydrates. The gland itself can also be injured; for example, neoplasias, which have been considered the most important, causing damage of to the gland and are difficult to diagnose. There are several types of thyroid cancer: Papillary, Follicular, Medullary, and Anaplastic. The occurrence rate, in general is between 4 and 7%; which is on the increase (30%), probably due to new technology that is able to find small thyroid cancers that may not have been found previously. The most common method used for thyroid diagnoses are: anamnesis, ultrasonography, and laboratory exams (Fine Needle Aspiration Biopsy- FNAB). However, the sensitivity of those test are rather poor, with a high rate of false-negative results, therefore there is an urgent need to develop new diagnostic techniques. Raman spectroscopy has been presented as a valuable tool for cancer diagnosis in many different tissues. In this work, 27 fragments of the thyroid were collected from 18 patients, comprising the following histologic groups: goitre adjacent tissue, goitre nodular tissue, follicular adenoma, follicular carcinoma, and papillary carcinoma. Spectral collection was done with a commercial FTRaman Spectrometer (Bruker RFS100/S) using a 1064 nm laser excitation and Ge detector. Principal Component Analysis, Cluster Analysis, and Linear Discriminant Analysis with cross-validation were applied as spectral classification algorithm. Comparing the goitre adjacent tissue with the goitre nodular region, an index of 58.3% of correct classification was obtained. Between goitre (nodular region and

  17. Raman spectroscopy: an evolving technique for live cell studies.

    PubMed

    Smith, Rachael; Wright, Karen L; Ashton, Lorna

    2016-06-21

    One of the most exciting developments in Raman spectroscopy in the last decade has been its application to cells and tissues for diagnostic and pharmaceutical applications, and in particular its use in the analysis of cellular dynamics. Raman spectroscopy is rapidly advancing as a cell imaging method that overcomes many of the limitations of current techniques and is earning its place as a routine tool in cell biology. In this review we focus on important developments in Raman spectroscopy that have evolved into the exciting technique of live-cell Raman microscopy and highlight some of the most recent and significant applications to cell biology. PMID:27072718

  18. Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters

    PubMed Central

    Jokerst, Jesse V.; Pohling, Christoph; Gambhir, Sanjiv S.

    2013-01-01

    Molecular imaging scans cellular and molecular targets in living subjects through the introduction of imaging agents that bind to these targets and report their presence through a measurable signal. The picomolar sensitivity, signal stability, and high multiplexing capacity of Raman spectroscopy satisfies important needs within the field of molecular imaging, and several groups now utilize Raman and surface-enhanced Raman spectroscopy to image molecular targets in small animal models of human disease. This article details the role of Raman spectroscopy in molecular imaging, describes some substrates and imaging agents used in animal models, and illustrates some examples. PMID:24293809

  19. Cervical cancer detection based on serum sample Raman spectroscopy.

    PubMed

    González-Solís, José Luis; Martínez-Espinosa, Juan Carlos; Torres-González, Luis Adolfo; Aguilar-Lemarroy, Adriana; Jave-Suárez, Luis Felipe; Palomares-Anda, Pascual

    2014-05-01

    The use of Raman spectroscopy to analyze the biochemical composition of serum samples and hence distinguish between normal and cervical cancer serum samples was investigated. The serum samples were obtained from 19 patients who were clinically diagnosed with cervical cancer, 3 precancer, and 20 healthy volunteer controls. The imprint was put under an Olympus microscope, and around points were chosen for Raman measurement.All spectra were collected at a Horiba Jobin-Yvon LabRAM HR800 Raman Spectrometer with a laser of 830-nm wavelength and 17-mW power irradiation. Raw spectra were processed by carrying out baseline correction, smoothing, and normalization to remove noise, florescence, and shot noise and then analyzed using principal component analysis (PCA). The control serum spectrum showed the presence of higher amounts of carotenoids indicated by peaks at 1,002, 1,160, and 1,523 cm(-1)and intense peaks associated with protein components at 754, 853, 938, 1,002, 1,300-1,345, 1,447, 1,523, 1,550, 1,620, and 1,654 cm(-1). The Raman bands assigned to glutathione (446, 828, and 1,404 cm(-1)) and tryptophan (509, 1,208, 1,556, 1,603, and 1,620 cm(-1)) in cervical cancer were higher than those of control samples, suggesting that their presence may also play a role in cervical cancer. Furthermore, weak bands in the control samples attributed to tryptophan (545, 760, and 1,174 cm(-1)) and amide III (1,234-1,290 cm(-1)) seem to disappear and decrease in the cervical cancer samples, respectively. It is shown that the serum samples from patients with cervical cancer and from the control group can be discriminated with high sensitivity and specificity when the multivariate statistical methods of PCA is applied to Raman spectra. PCA allowed us to define the wavelength differences between the spectral bands of the control and cervical cancer groups by confirming that the main molecular differences among the control and cervical cancer samples were glutathione, tryptophan,

  20. Evaluating internal maturity of tomatoes using spatially offset Raman spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatially offset Raman spectroscopy technique was investigated for evaluating internal maturity of intact tomatoes. A Raman spectroscopy system was assembled to acquire spatially offset spectra in the wavenumber range of 200–2500 cm–1. A 785-nm laser was used as the excitation source and the measure...

  1. Measurement of clathrate hydrates via Raman spectroscopy

    USGS Publications Warehouse

    Sum, A.K.; Burruss, R.C.; Sloan, E.D., Jr.

    1997-01-01

    Raman spectra of clathrate hydrate guest molecules are presented for three known structures (I (sI), II (sII), and H (sH)) in the following systems: CH4 (sI), CO2 (sI), C3H8 (sII), CH4 + CO2 (sI), CD4 + C3H8 (sII), CH4 + N2 (sI), CH4 + THF-d8 (sII), and CH4 + C7D14 (sH). Relative occupancy of CH4 in the large and small cavities of sI were determined by deconvoluting the ??1 symmetric bands, resulting in hydration numbers of 6.04 ?? 0.03. The frequency of the ??1 bands for CH4 in structures I, II, and H differ statistically, so that Raman spectroscopy is a potential tool to identify hydrate crystal structure. Hydrate guest compositions were also measured for two vapor compositions of the CH4 + CO2 system, and they compared favorably with predictions. The large cavities were measured to be almost fully occupied by CH4 and CO2, whereas only a small fraction of the small cavities are occupied by CH4. No CO2 was found in the small cavities. Hydration numbers from 7.27 to 7.45 were calculated for the mixed hydrate.

  2. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    SciTech Connect

    Melendres, C.A.

    1988-01-01

    Laser Raman Spectroscopy (LRS) has become an important tool for the in-situ structural study of electrochemical systems and processes in recent years. Following a brief introduction of the experimental techniques involved in applying LRS to electrochemical systems, we survey the literature for examples of studies in the inhibition of electrode reactions by surface films (e.g., corrosion and passivation phenomena) as well as the acceleration of reactions by electro-sorbates (electrocatalysis). We deal mostly with both normal and resonance Raman effects on fairly thick surface films in contrast to surface-enhanced Raman investigations of monolayer adsorbates, which is covered in another lecture. Laser Raman spectroelectrochemical studies of corrosion and film formation on such metals as Pb, Ag, Fe, Ni, Co, Cr, Au, stainless steel, etc. in various solution conditions are discussed. Further extension of the technique to studies in high-temperature and high-pressure aqueous environments is demonstrated. Results of studies of the structure of corrosion inhibitors are also presented. As applications of the LRS technique in the area of electrocatalysis, we cite studies of the structure of transition metal macrocyclic compounds, i.e., phthalocyanines and porphyrins, used for catalysis of the oxygen reduction reaction. 104 refs., 20 figs.

  3. Surface-enhanced Raman spectroscopy of peptides

    NASA Astrophysics Data System (ADS)

    Garrell, Robin L.; Herne, Tonya M.; Ahern, Angela M.; Sullenberger, Eve L.

    1990-07-01

    Surface-enhanced Raman (SER) spectroscopy has been used to probe the adsorption, surface interactions, and orientations of peptides on metal surfaces. Amino acids in homodipeptides give SER spectra with unique features that can be used to characterize the surface interactions of specific functional groups in more complicated peptides. In heterodipeptides, there is a hierarchy of functional group-surface interactions that prescribe their orientation and conformation on metal surfaces. By establishing this hierarchy, it is now possible to predict the interactions that occur between larger peptides and surfaces. Furthermore, the observed trends suggest that it should be possible to control these interactions by varying the solution pH, the charge on the surface, and other parameters of the measurement in order to adsorb species selectively from mixtures of peptides in solution. Potential biomedical applications of this technique will be described.

  4. Molecular velocimetry using stimulated Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Exton, R. J.; Hillard, M. E.

    1984-01-01

    Molecular flow velocity of N2 was measured in a supersonic wind tunnel using inverse Raman spectroscopy. This technique employs the large Doppler shift exhibited by the molecules when the pump and probe laser beams are counter-propagating (backward scattering). A retrometer system is employed to yield a vibration-free optical configuration which has the additional advantage of obtaining both the forward and backward scattered spectra simultaneously. The linebreadths and their relative Doppler shift can be used to determine the static pressure, translational temperature, and molecular flow velocity. A demonstration of the concept was performed in a supersonic wind tunnel and included: (1) measurements over the Mach number range 2.50 to 4.63; (2) static pressure measurements (at Mach 2.50) corresponding to a Reynolds number per foot range of 1 to 5 x 10 to the 6th power; and (3) measurements behind the shock wave of a flat plate model.

  5. FT Raman spectroscopy of Norway spruce needles

    NASA Astrophysics Data System (ADS)

    Matejka, P.; Pleserova, L.; Budinova, G.; Havirova, K.; Nahlik, J.; Skacel, F.; Volka, Karel

    2001-02-01

    12 Norway spruce [Picea abies (L.) Karst.] needles represent a very useful bioindicator of the air pollution. They serve not only as natural samplers of the pollutants but micromorphology of the epistomatal area can be directly correlated with an environmental stress. The needles of trees growing in polluted areas exhibit different types of injury to the epicuticular wax layer. It is evident that these changes of the morphology of the wax layers are connected also with the changes of their chemical composition and so a potential of the FT Raman spectroscopy was tested to serve as a screening method of these changes. In this work variability of the spectra with the age and with the position in the tree, in the locality, and also in the different localities of the Czech Republic was studied and evaluated in comparison with results of electron scanning microscopy.

  6. Detection of hazardous chemicals using field-portable Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wright, Cherylyn W.; Harvey, Scott D.; Wright, Bob W.

    2003-07-01

    A major challenge confronting emergency response, border control, and other security-related functions is the accurate, rapid, and safe identification of potentially hazardous chemicals outside a laboratory environment. Raman spectroscopy is a rapid, non-intrusive technique that can be used to confidently identify many classes of hazardous and potentially explosive compounds based on molecular vibration information. Advances in instrumentation now allow reliable field - portable measurements to be made. Before the Raman technique can be effectively applied and be accepted within the scientific community, realistic studies must be performed to develop methods, define limitations, and rigorously evaluate its effectiveness. Examples of a variety of chemicals (including neat and diluted chemical warfare [CW] agents, a CW agent precursor, a biological warfare (BW)-related compound, an illicit drug, and explosives) identified using Raman spectroscopy in various types of containers and on surfaces are given, as well as results from a blind field test of 29 unknown samples which included CW agent precursors and/or degradation products, solvents associated with CW agent production, pesticides, explosives, and BW toxins (mostly mycotoxins). Additionally, results of experimental studies to evaluate the analysis of flammable organic solvents, propellants, military explosives, mixtures containing military explosives, shock-sensitive explosives, and gun powders are described with safety guidelines. Spectral masks for screening unknown samples for explosives and nerve agents are given.

  7. [The Quantitative Analysis of Raman Spectroscopy to Sulfate Ion in Aqueous Solution].

    PubMed

    Wang, Qian-qian; Sun, Qiang

    2016-02-01

    As a non-destructive and non-contact method, Raman spectroscopy has been widely applied in many research fields. Based on vibrational wavenumber, Raman spectroscopy is usually applied to determine the molecular species. Therefore, Raman quantitative analysis is necessary. In this study, according to the theoretical analysis of Raman intensity, Raman quantitative measurement should be fulfilled by relative intensity ratio, which can be divided into internal and external standards. This eliminates the influence of the measurement conditions. For aqueous solution, it is reasonable to treat the OH stretching band of water as an internal standard to determine the solute concentrations in aqueous solution. The Raman spectra of Na₂SO₄-H₂O, K₂SO₄-H₂O and NaCl-Na₂SO₄-H₂O are recorded in the paper. In addition, the Raman OH stretching band of water can be fitted into two Gaussian sub-bands. The intensity proportion I(SO₄²⁻)/I(W) is used to determine the molarity of sulfate in aqueous solution, where I(SO₄²⁻) represents the intensity of sulfate band and I(W) represents the sum of the two sub-bands of Raman OH stretching bands of water. Therefore, Raman spectroscopy can be utilized to measure the SO₄²⁻concentrations in aqueous solutions. PMID:27209744

  8. FT-Raman, surface-enhanced Raman spectroscopy and theoretical investigations of diclofenac sodium

    NASA Astrophysics Data System (ADS)

    Iliescu, T.; Baia, M.; Kiefer, W.

    2004-03-01

    Raman and surface-enhanced Raman (SER) spectroscopies have been applied to the vibrational characterization of diclofenac sodium (DCF-Na). Theoretical calculations (DFT and ab initio) of two DCF-Na conformers have been performed to find the optimized structure and computed vibrational wavenumbers of the most stable one. SER spectra in silver colloid at different pH values have been also recorded and analyzed. Good SER spectra have been obtained in acidic and neutral environments, proving the chemisorption of the DCF-Na molecule on the silver surface. In the investigated pH range the carboxylate anion has been bonded to the silver surface through the lone pair oxygen electrons. The phenyl rings' orientation with respect to the silver surface changed on passing from acidic to neutral pH from a tilted close to flat to a more perpendicular one.

  9. Raman spectroscopy of human saliva for acute myocardial infarction detection

    NASA Astrophysics Data System (ADS)

    Chen, Maowen; Chen, Yuanxiang; Wu, Shanshan; Huang, Wei; Lin, Jinyong; Weng, Guo-Xing; Chen, Rong

    2014-09-01

    Raman spectroscopy is a rapidly non-invasive technique with great potential for biomedical research. The aim of this study was to evaluate the feasibility of using Raman spectroscopy of human saliva for acute myocardial infarction (AMI) detection. Raman spectroscopy measurements were performed on two groups of saliva samples: one group from patients (n=30) with confirmed AMI and the other group from healthy controls (n=31). The diagnostic performance for differentiating AMI saliva from normal saliva was evaluated by multivariate statistical analysis. The combination of principal component analysis (PCA) and linear discriminate analysis (LDA) of the measured Raman spectra separated the spectral features of the two groups into two distinct clusters with little overlaps, rendering the sensitivity of 80.0% and specificity of 80.6%. The results from this exploratory study demonstrated that Raman spectroscopy of human saliva can serve as a potentially clinical tool for rapid AMI detection and screening.

  10. Raman spectroscopy for optical diagnosis of laryngeal cancer

    NASA Astrophysics Data System (ADS)

    Teh, Seng Khoon; Zheng, Wei; Lau, David P.; Huang, Zhiwei

    2008-02-01

    In this report, the diagnostic ability of near-infrared (NIR) Raman spectroscopy for identifying the malignant tumors from normal tissues in the larynx was studied. A rapid NIR Raman system was utilized. Multivariate statistical techniques were employed to develop effective diagnostic algorithms. Raman spectra in the range of 800-1,800 cm-1 differed significantly between normal and malignant tumor tissues. The diagnostic algorithms can yielded a diagnostic sensitivity of 92.9% and specificity 83.3% for separating malignant tumors from normal laryngeal tissues. NIR Raman spectroscopy with multivariate statistical techniques has a potential for the non-invasive detection of malignant tumors in the larynx.

  11. From Femtosecond Dynamics to Breast Cancer Diagnosis by Raman Spectroscopy

    SciTech Connect

    Abramczyk, H.; Placek, I.; Brozek-Pluska, B.; Kurczewski, K.; Morawiec, Z.; Tazbir, M.

    2007-12-26

    This paper presents new results based on Raman spectroscopy and demonstrates its utilisation as a diagnostic and development tool with the key advantage in breast cancer research. Applications of Raman spectroscopy in cancer research are in the early stages of development. However, research presented here as well as performed in a few other laboratories demonstrate the ability of Raman spectroscopy to accurately characterize cancer tissue and distinguish between normal, malignant and benign types. The main goals of bio-Raman spectroscopy at this stage are threefold. Firstly, the aim is to develop the diagnostic ability of Raman spectroscopy so it can be implemented in a clinical environment, producing accurate and rapid diagnoses. Secondly, the aim is to optimize the technique as a diagnostic tool for the non-invasive real time medical applications. Thirdly, the aim is to formulate some hypothesis based on Raman spectroscopy on the molecular mechanism which drives the transformation of normal human cells into highly malignant derivatives. To the best of our knowledge, this is the most statistically reliable report on Raman spectroscopy-based diagnosis of breast cancers among the world women population.

  12. From Femtosecond Dynamics to Breast Cancer Diagnosis by Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Abramczyk, H.; Placek, I.; BroŻek-Płuska, B.; Kurczewski, K.; Morawiec, Z.; Tazbir, M.

    2007-12-01

    This paper presents new results based on Raman spectroscopy and demonstrates its utilisation as a diagnostic and development tool with the key advantage in breast cancer research. Applications of Raman spectroscopy in cancer research are in the early stages of development. However, research presented here as well as performed in a few other laboratories demonstrate the ability of Raman spectroscopy to accurately characterize cancer tissue and distinguish between normal, malignant and benign types. The main goals of bio-Raman spectroscopy at this stage are threefold. Firstly, the aim is to develop the diagnostic ability of Raman spectroscopy so it can be implemented in a clinical environment, producing accurate and rapid diagnoses. Secondly, the aim is to optimize the technique as a diagnostic tool for the non-invasive real time medical applications. Thirdly, the aim is to formulate some hypothesis based on Raman spectroscopy on the molecular mechanism which drives the transformation of normal human cells into highly malignant derivatives. To the best of our knowledge, this is the most statistically reliable report on Raman spectroscopy-based diagnosis of breast cancers among the world women population.

  13. The many facets of Raman spectroscopy for biomedical analysis.

    PubMed

    Krafft, Christoph; Popp, Jürgen

    2015-01-01

    A critical review is presented on the use of linear and nonlinear Raman microspectroscopy in biomedical diagnostics of bacteria, cells, and tissues. This contribution is combined with an overview of the achievements of our research group. Linear Raman spectroscopy offers a wealth of chemical and molecular information. Its routine clinical application poses a challenge due to relatively weak signal intensities and confounding overlapping effects. Nonlinear variants of Raman spectroscopy such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) have been recognized as tools for rapid image acquisition. Imaging applications benefit from the fact that contrast is based on the chemical composition and molecular structures in a label-free and nondestructive manner. Although not label-free, surface enhanced Raman scattering (SERS) has also been recognized as a complementary biomedical tool to increase sensitivity. The current state of the art is evaluated, illustrative examples are given, future developments are pointed out, and important reviews and references from the current literature are selected. The topics are identification of bacteria and single cells, imaging of single cells, Raman activated cell sorting, diagnosis of tissue sections, fiber optic Raman spectroscopy, and progress in coherent Raman scattering in tissue diagnosis. The roles of networks-such as Raman4clinics and CLIRSPEC on a European level-and early adopters in the translation, dissemination, and validation of new methods are discussed. PMID:25428454

  14. Raman spectroscopy of gliomas: an exploratory study

    NASA Astrophysics Data System (ADS)

    Shenoy, Mahesh; Hole, Arti R.; Shridhar, E.; Moiyadi, Aliasgar V.; Krishna, C. Murali

    2014-03-01

    Gliomas are extremely infiltrative type of brain cancers, the borders of which are difficult to locate. Gliomas largely consist of tumors of astrocytic or oligodendroglial lineage. Usually stereotactic surgery is performed to obtain tumor tissue sample. Complete excision of these tumors with preservation of uninvolved normal areas is important during brain tumor surgeries. The present study was undertaken to explore feasibility of classifying abnormal and normal glioma tissues with Raman spectroscopy (RS). RS is a nondestructive vibrational spectroscopic technique, which provides information about molecular composition, molecular structures and molecular interactions in tissue. Postoperated 33 (20-abnormal and 13-normal) gliomas tissue samples of different grades were collected under clinical supervision. Five micron section from tissue sample was used for confirmatory histopathological diagnosis while the remaining tissue was placed on CaF2 window and spectra were acquired using a fiberoptic-probe-coupled HE-785 Raman-spectrometer. Spectral acquisition parameters were laser power-80mW, integration-20s and averaged over 3 accumulations. Spectra were pre-processed and subjected to unsupervised Principal-Component Analysis (PCA) to identify trends of classification. Supervised PC-LDA (Principal-Component-Linear-Discriminant Analysis) was used to develop standard-models using spectra of 12 normal and abnormal specimens each. Leave-one-out crossvalidation yielded classification-efficiency of 90% and 80% for normal and abnormal conditions, respectively. Evaluation with an independent-test data-set comprising of 135 spectra of 9 samples provided sensitivity of 100% and specificity of 70%. Findings of this preliminary study may pave way for objective tumor margin assessment during brain surgery.

  15. New Applications of Portable Raman Spectroscopy in Agri-Bio-Photonics

    NASA Astrophysics Data System (ADS)

    Voronine, Dmitri; Scully, Rob; Sanders, Virgil

    2014-03-01

    Modern optical techniques based on Raman spectroscopy are being used to monitor and analyze the health of cattle, crops and their natural environment. These optical tools are now available to perform fast, noninvasive analysis of live animals and plants in situ. We will report new applications of a portable handheld Raman spectroscopy to identification and taxonomy of plants. In addition, detection of organic food residues will be demonstrated. Advantages and limitations of current portable instruments will be discussed with suggestions for improved performance by applying enhanced Raman spectroscopic schemes.

  16. Nanoparticle Based Surface-Enhanced Raman Spectroscopy

    SciTech Connect

    Talley, C E; Huser, T R; Hollars, C W; Jusinski, L; Laurence, T; Lane, S M

    2005-01-03

    Surface-enhanced Raman scattering is a powerful tool for the investigation of biological samples. Following a brief introduction to Raman and surface-enhanced Raman scattering, several examples of biophotonic applications of SERS are discussed. The concept of nanoparticle based sensors using SERS is introduced and the development of these sensors is discussed.

  17. Periodontitis diagnostics using resonance Raman spectroscopy on saliva

    NASA Astrophysics Data System (ADS)

    Gonchukov, S.; Sukhinina, A.; Bakhmutov, D.; Biryukova, T.; Tsvetkov, M.; Bagratashvily, V.

    2013-07-01

    In view of its wealth of molecular information, Raman spectroscopy has been the subject of active biomedical research. The aim of this work is Raman spectroscopy (RS) application for the determination of molecular biomarkers in saliva with the objective of early periodontitis detection. As was shown in our previous study, carotenoids contained in saliva can be molecular fingerprint information for the periodontitis level. It is shown here that the carotenoid RS lines at wavenumbers of 1156 and 1524 cm-1 can be easily detected and serve as reliable biomarkers of periodontitis using resonance Raman spectroscopy of dry saliva.

  18. Investigation of biomineralization by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Fatscher, Robert William

    Biomineralization is a process in which living organism grow composite materials consisting of inorganic and organic materials. This produces a composite material consisting of both inorganic and organic components, with superior mechanical properties. In the human body bone and dentin are both examples of biominerals. In this research Raman spectroscopy was used to characterize dentin from mice and human teeth, to determine composition. In the mouse tooth samples areas of irregular dentin were found, along the inside of the tooth, to be in the process of mineralization. By analyzing the samples along these areas we were able to determine the composition of dentin and track how it changed in these area. By analysis of the mineral to matrix ratio the areas of irregular dentin were determined to have less mineral present. Observations of other organic components and collagen in increased concentrations in this area suggested these area were in the process of biomineralization. The understanding of the structure of dentin and its biomineralization process is of crucial importance when trying reproduce dentin. Scientists and engineers are able to produce dentin minerals in vitro by culturing various dental stem cells. The ability to create dentin mineral from cells could lead to methods of repairing dentin in patients, or even lead to the creation of a completely engineered tooth. While dentin-like materials can be produced in a laboratory environment, analysis and comparison of the composition of these materials must be performed to ensure the mineral produced is consistent with dentin. Mineralized nodules from six different dental stem cell lines were cultured to produce a mineralized deposit. Utilizing Raman spectroscopy, we were able to determine cell source dependent differences in a variety of dental stem cells, and compare the mineral produced to native dentin. Orthopedic implants are implants used to replace damaged bone, examples include knee, hip and dental

  19. Sensitivity of Raman spectroscopy to normal patient variability

    NASA Astrophysics Data System (ADS)

    Vargis, Elizabeth; Byrd, Teresa; Logan, Quinisha; Khabele, Dineo; Mahadevan-Jansen, Anita

    2011-11-01

    Many groups have used Raman spectroscopy for diagnosing cervical dysplasia; however, there have been few studies looking at the effect of normal physiological variations on Raman spectra. We assess four patient variables that may affect normal Raman spectra: Race/ethnicity, body mass index (BMI), parity, and socioeconomic status. Raman spectra were acquired from a diverse population of 75 patients undergoing routine screening for cervical dysplasia. Classification of Raman spectra from patients with a normal cervix is performed using sparse multinomial logistic regression (SMLR) to determine if any of these variables has a significant effect. Results suggest that BMI and parity have the greatest impact, whereas race/ethnicity and socioeconomic status have a limited effect. Incorporating BMI and obstetric history into classification algorithms may increase sensitivity and specificity rates of disease classification using Raman spectroscopy. Studies are underway to assess the effect of these variables on disease.

  20. Clinical instrumentation and applications of Raman spectroscopy.

    PubMed

    Pence, Isaac; Mahadevan-Jansen, Anita

    2016-04-01

    Clinical diagnostic devices provide new sources of information that give insight about the state of health which can then be used to manage patient care. These tools can be as simple as an otoscope to better visualize the ear canal or as complex as a wireless capsule endoscope to monitor the gastrointestinal tract. It is with tools such as these that medical practitioners can determine when a patient is healthy and to make an appropriate diagnosis when he/she is not. The goal of diagnostic medicine then is to efficiently determine the presence and cause of disease in order to provide the most appropriate intervention. The earliest form of medical diagnostics relied on the eye - direct visual observation of the interaction of light with the sample. This technique was espoused by Hippocrates in his 5th century BCE work Epidemics, in which the pallor of a patient's skin and the coloring of the bodily fluids could be indicative of health. In the last hundred years, medical diagnosis has moved from relying on visual inspection to relying on numerous technological tools that are based on various types of interaction of the sample with different types of energy - light, ultrasound, radio waves, X-rays etc. Modern advances in science and technology have depended on enhancing technologies for the detection of these interactions for improved visualization of human health. Optical methods have been focused on providing this information in the micron to millimeter scale while ultrasound, X-ray, and radio waves have been key in aiding in the millimeter to centimeter scale. While a few optical technologies have achieved the status of medical instruments, many remain in the research and development phase despite persistent efforts by many researchers in the translation of these methods for clinical care. Of these, Raman spectroscopy has been described as a sensitive method that can provide biochemical information about tissue state while maintaining the capability of delivering

  1. Clinical instrumentation and applications of Raman spectroscopy

    PubMed Central

    Pence, Isaac

    2016-01-01

    Clinical diagnostic devices provide new sources of information that give insight about the state of health which can then be used to manage patient care. These tools can be as simple as an otoscope to better visualize the ear canal or as complex as a wireless capsule endoscope to monitor the gastrointestinal tract. It is with tools such as these that medical practitioners can determine when a patient is healthy and to make an appropriate diagnosis when he/she is not. The goal of diagnostic medicine then is to efficiently determine the presence and cause of disease in order to provide the most appropriate intervention. The earliest form of medical diagnostics relied on the eye – direct visual observation of the interaction of light with the sample. This technique was espoused by Hippocrates in his 5th century BCE work Epidemics, in which the pallor of a patient’s skin and the coloring of the bodily fluids could be indicative of health. In the last hundred years, medical diagnosis has moved from relying on visual inspection to relying on numerous technological tools that are based on various types of interaction of the sample with different types of energy – light, ultrasound, radio waves, X-rays etc. Modern advances in science and technology have depended on enhancing technologies for the detection of these interactions for improved visualization of human health. Optical methods have been focused on providing this information in the micron to millimeter scale while ultrasound, X-ray, and radio waves have been key in aiding in the millimeter to centimeter scale. While a few optical technologies have achieved the status of medical instruments, many remain in the research and development phase despite persistent efforts by many researchers in the translation of these methods for clinical care. Of these, Raman spectroscopy has been described as a sensitive method that can provide biochemical information about tissue state while maintaining the capability of

  2. [Water Raman spectrum suppression with low-pass filter in underwater in-situ Raman spectroscopy].

    PubMed

    Guo, Jin-Jia; Liu, Zhi-Shen

    2011-09-01

    As a powerful tool for studying chemical structures, Raman spectroscopy has been used in aquatic environments in-situ measurement widely, and has been used in deep sea research recently. For underwater in-situ detection, O-H vibration Raman peak of water is inherent and strong compared with other dissolved matter's Raman signals. When the authors want to get a good SNR Raman signal of dissolved matter by increasing detection time, O-H vibration Raman peak of water will get to saturation easily, which influences other Raman signal's detection. In the present paper, a specially designed short-pass optical filter was used for suppression of water's O-H vibration Raman peak. The authors calculated the suppression effect of short-pass optical filter with linear and exponential edges. The simulation shows that exponential edge filter has better performance and can suppress water's O-H vibration Raman peak effectively. The experiment also proves the calculation results. With the suppression optical filter, the intensity of water's O-H vibration Raman signal and other dissolved matters' become similar. And the influence of suppression optical filter on other dissolved matters' Raman signal is little. So the suppression optical filter is feasible for in-situ underwater Raman spectroscopy. PMID:22097842

  3. Application of Raman Spectroscopy for Nondestructive Evaluation of Composite Materials

    NASA Technical Reports Server (NTRS)

    Washer, Glenn A.; Brooks, Thomas M. B.; Saulsberry, Regor

    2007-01-01

    This paper will present an overview of efforts to investigate the application of Raman spectroscopy for the characterization of Kevlar materials. Raman spectroscopy is a laser technique that is sensitive to molecular interactions in materials such as Kevlar, graphite and carbon used in composite materials. The overall goal of this research reported here is to evaluate Raman spectroscopy as a potential nondestructive evaluation (NDE) tool for the detection of stress rupture in Kevlar composite over-wrapped pressure vessels (COPVs). Characterization of the Raman spectra of Kevlar yarn and strands will be presented and compared with analytical models provided in the literature. Results of testing to investigate the effects of creep and high-temperature aging on the Raman spectra will be presented.

  4. Applications of spatially offset Raman spectroscopy to defense and security

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Hopkins, Rebecca

    2016-05-01

    Spatially offset Raman spectroscopy (SORS) allows for sub-surface and through barrier detection and has applications in drug analysis, cancer detection, forensic science, as well as defense and security. This paper reviews previous efforts in SORS and other through barrier Raman techniques and presents a discussion on current research in defense and security applications.

  5. Cryoprotectant redistribution along the frozen straw probed by Raman spectroscopy.

    PubMed

    Karpegina, Yu A; Okotrub, K A; Brusentsev, E Yu; Amstislavsky, S Ya; Surovtsev, N V

    2016-04-01

    The distribution of cryoprotectant (10% glycerol) and ice along the frozen plastic straw (the most useful container for freezing mammalian semen, oocytes and embryos) was studied by Raman scattering technique. Raman spectroscopy being a contactless, non-invasive tool was applied for the straws filled with the cryoprotectant solution and frozen by controlled rate programs commonly used for mammalian embryos freezing. Analysis of Raman spectra measured at different points along the straw reveals a non-uniform distribution of the cryoprotectant. The ratio between non-crystalline solution and ice was found to be increased by several times at the bottom side of the solution column frozen by the standard freezing program. The increase of the cryoprotectant fraction occurs in the area where embryos or oocytes are normally placed during their freezing. Possible effects of the cooling rate and the ice nucleation temperature on the cryoprotectant fraction at the bottom side of the solution column were considered. Our findings highlight that the ice fraction around cryopreserved embryos or oocytes can differ significantly from the averaged one in the frozen plastic straws. PMID:26794460

  6. Electrochemical Tip-Enhanced Raman Spectroscopy.

    PubMed

    Zeng, Zhi-Cong; Huang, Sheng-Chao; Wu, De-Yin; Meng, Ling-Yan; Li, Mao-Hua; Huang, Teng-Xiang; Zhong, Jin-Hui; Wang, Xiang; Yang, Zhi-Lin; Ren, Bin

    2015-09-23

    Interfacial properties are highly important to the performance of some energy-related systems. The in-depth understanding of the interface requires highly sensitive in situ techniques that can provide fingerprint molecular information at nanometer resolution. We developed an electrochemical tip-enhanced Raman spectroscopy (EC-TERS) by introduction of the light horizontally to the EC-STM cell to minimize the optical distortion and to keep the TERS measurement under a well-controlled condition. We obtained potential-dependent EC-TERS from the adsorbed aromatic molecule on a Au(111) surface and observed a substantial change in the molecule configuration with potential as a result of the protonation and deprotonation of the molecule. Such a change was not observable in EC-SERS (surface-enhanced), indicating EC-TERS can more faithfully reflect the fine interfacial structure than EC-SERS. This work will open a new era for using EC-TERS as an important nanospectroscopy tool for the molecular level and nanoscale analysis of some important electrochemical systems including solar cells, lithium ion batteries, fuel cells, and corrosion. PMID:26351986

  7. [Identification of B jade by Raman spectroscopy].

    PubMed

    Zu, En-dong; Chen, Da-peng; Zhang, Peng-xiang

    2003-02-01

    Raman spectroscopy has been found to be a useful tool for identification of bleached and polymer-impregnated jadeites (so-called B jade). The major advantage of this system over classical methods of gem testing is the non-destructive identification of inclusions in gemstones and the determination of organic fracture filling in jade. Fissures in jadeites have been filled with oils and various resins to enhance their clarity, such as paraffin wax, paraffin oil, AB glue and epoxy resins. They show different peaks depending on their chemical composition. The characteristic spectrum ranges from 1,200-1,700 cm-1 to 2,800-3,100 cm-1. The spectra of resins show that they all have four strongest peaks related with phenyl: two C-C stretching modes at 1,116 and 1,609 cm-1, respectively, one C-H stretching mode at 3,069 cm-1, and a in-plane C-H bending mode at 1,189 cm-1. In addition, other two -CH2, -CH3 stretching modes at 2,906 and 2,869 cm-1, respectively, are very similar to paraffin. Therefore, the peaks at 1,116, 1,609, 1,189 and 3,069 cm-1 are important in distinguishing resin from paraffin, and we can identify B jade depending on them. PMID:12939970

  8. Wavelength dependent resonance Raman band intensity of broadband stimulated Raman spectroscopy of malachite green in ethanol

    NASA Astrophysics Data System (ADS)

    Cen, Qiongyan; He, Yuhan; Xu, Mei; Wang, Jingjing; Wang, Zhaohui

    2015-03-01

    Resonance broadband stimulated Raman spectroscopy of malachite green in ethanol has been performed. With a tuning picosecond visible laser source and a broadband Raman probe, the Raman gain and loss spectra have been measured simultaneously. By scanning the Raman pump across the first absorption band of the molecule, we found that the resonant Raman bands could be only seen when the pump laser tuned in the range of the red edge of the S1←S0 transition. Dispersive lineshapes of resonant Raman bands have been observed in the Raman loss spectra, while the line shape is normal (same as spontaneous Raman) in the Raman gain spectra. Although, the resonant bands in the loss spectrum are usually stronger than that in the gain spectrum, the band intensities of both loss and gain linearly increase with the pump energy. The relative magnitude of each corresponding resonant band in the Raman loss and gain varies with the pump wavelength. Mode specified Raman excitation profiles have been obtained through broadband stimulated Raman measurement.

  9. Raman Spectroscopy for the Investigation of Carbon Based Black Pigments

    NASA Astrophysics Data System (ADS)

    Coccato, A.; Jehlicka, J.; Moens, L.; Vandenabeele, P.

    2014-06-01

    Carbon based black pigments play an important role among artists' materials. The disordered structure of these materials is investigated by means of Raman spectroscopy, which helps in the comprehension of their production processes.

  10. Analysis of Arctic Carbonates Profiles by Raman Spectroscopy using Exomars Raman Laser Spectrometer

    NASA Astrophysics Data System (ADS)

    Sansano, A.; López, G.; Medina, J.; Rull, F.

    2011-10-01

    This work details the analysis performed by Raman spectroscopy on carbonate samples from the Svalbard Islands (Norway) in the Arctic. This place is considered a potential Martian analog because the carbonate formation show close similarities with the formation in ALH84001 meteorite. The results obtained illustrate the performances of the Raman instrument included in the Exomars (ESA) mission.

  11. Spatially offset Raman spectroscopy based on a line-scan hyperspectral Raman system

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spatially offset Raman spectroscopy (SORS) is a technique that can obtain subsurface layered information by collecting Raman spectra from a series of surface positions laterally offset from the excitation laser. The current methods of SORS measurement are typically either slow due to mechanical move...

  12. Quantitative Raman spectroscopy in turbid media

    NASA Astrophysics Data System (ADS)

    Reble, Carina; Gersonde, Ingo; Andree, Stefan; Eichler, Hans Joachim; Helfmann, Jürgen

    2010-05-01

    Intrinsic Raman spectra of biological tissue are distorted by the influences of tissue absorption and scattering, which significantly challenge signal quantification. A combined Raman and spatially resolved reflectance setup is introduced to measure the absorption coefficient μa and the reduced scattering coefficient μs' of the tissue, together with the Raman signals. The influence of μa and μs' on the resonance Raman signal of β-carotene is measured at 1524 cm-1 by tissue phantom measurements and Monte Carlo simulations for μa=0.01 to 10 mm-1 and μs'=0.1 to 10 mm-1. Both methods show that the Raman signal drops roughly proportional to 1/μa for μa>0.2 mm-1 in the measurement geometry and that the influence of μs' is weaker, but not negligible. Possible correction functions dependent on the elastic diffuse reflectance are investigated to correct the Raman signal for the influence of μa and μs', provided that μa and μs' are measured as well. A correction function based on the Monte Carlo simulation of Raman signals is suggested as an alternative. Both approaches strongly reduce the turbidity-induced variation of the Raman signals and allow absolute Raman scattering coefficients to be determined.

  13. Micro-Raman spectroscopy for meat type detection

    NASA Astrophysics Data System (ADS)

    De Biasio, M.; Stampfer, P.; Leitner, R.; Huck, C. W.; Wiedemair, V.; Balthasar, D.

    2015-06-01

    The recent horse meat scandal in Europe increased the demand for optical sensors that can identify meat type. Micro-Raman spectroscopy is a promising technique for the discrimination of meat types. Here, we present micro-Raman measurements of chicken, pork, turkey, mutton, beef and horse meat test samples. The data was analyzed with different combinations of data normalization and classification approaches. Our results show that Raman spectroscopy can discriminate between different meat types. Red and white meat are easily discriminated, however a sophisticated chemometric model is required to discriminate species within these groups.

  14. Dispersive Raman spectroscopy allows the identification and quantification of melanin types.

    PubMed

    Galván, Ismael; Jorge, Alberto

    2015-04-01

    Melanins are the most prevalent pigments in animals and are involved in visual communication by producing colored traits that often evolve as intraspecific signals of quality. Identifying and quantifying melanins are therefore essential to understand the function and evolution of melanin-based signals. However, the analysis of melanins is difficult due to their insolubility and the lack of simple methods that allow the identification of their chemical forms. We recently proposed the use of Raman spectroscopy as a simple, noninvasive technique that can be used to identify and quantify melanins in feathers and hairs. Contrarily, other authors later stated that melanins are characterized by a lack of defined Raman signals. Here, we use confocal Raman microscopy to confirm previous analyses showing that the two main chemical forms of melanins (eumelanin and pheomelanin) exhibit distinct Raman signal and compare different excitation wavelengths to analyze synthetic pheomelanin and natural melanins in feathers of different species of birds. Our analyses indicate that only laser excitation wavelengths below 1064 nm are useful for the analysis of melanins by Raman spectroscopy, and only 780-nm laser in the case of melanins in feathers. These findings show that the capacity of Raman spectroscopy to distinguish different chemical forms of melanins depends on laser power and integration time. As a consequence, Raman spectroscopy should be applied after preliminar analyses using a range of these parameters, especially in fragile biological tissues such as feathers. PMID:25897382

  15. Dispersive Raman spectroscopy allows the identification and quantification of melanin types

    PubMed Central

    Galván, Ismael; Jorge, Alberto

    2015-01-01

    Melanins are the most prevalent pigments in animals and are involved in visual communication by producing colored traits that often evolve as intraspecific signals of quality. Identifying and quantifying melanins are therefore essential to understand the function and evolution of melanin-based signals. However, the analysis of melanins is difficult due to their insolubility and the lack of simple methods that allow the identification of their chemical forms. We recently proposed the use of Raman spectroscopy as a simple, noninvasive technique that can be used to identify and quantify melanins in feathers and hairs. Contrarily, other authors later stated that melanins are characterized by a lack of defined Raman signals. Here, we use confocal Raman microscopy to confirm previous analyses showing that the two main chemical forms of melanins (eumelanin and pheomelanin) exhibit distinct Raman signal and compare different excitation wavelengths to analyze synthetic pheomelanin and natural melanins in feathers of different species of birds. Our analyses indicate that only laser excitation wavelengths below 1064 nm are useful for the analysis of melanins by Raman spectroscopy, and only 780-nm laser in the case of melanins in feathers. These findings show that the capacity of Raman spectroscopy to distinguish different chemical forms of melanins depends on laser power and integration time. As a consequence, Raman spectroscopy should be applied after preliminar analyses using a range of these parameters, especially in fragile biological tissues such as feathers. PMID:25897382

  16. Nanogap structures: combining enhanced Raman spectroscopy and electronic transport.

    PubMed

    Natelson, Douglas; Li, Yajing; Herzog, Joseph B

    2013-04-21

    Surface-enhanced Raman spectroscopy (SERS) is an experimental tool for accessing vibrational and chemical information, down to the single molecule level. SERS typically relies on plasmon excitations in metal nanostructures to concentrate the incident radiation and to provide an enhanced photon density of states to couple emitted radiation to the far field. Many common SERS platforms involve metal nanoparticles to generate the required electromagnetic enhancements. Here we concentrate on an alternative approach, in which the relevant plasmon excitations are supported at a truly nanoscale gap between extended electrodes, rather than discrete subwavelength nanoparticles. The ability to fabricate precise gaps on demand, and in some cases to tune the gap size in situ, combined with the additional capability of simultaneous electronic transport measurements of the nanogap, provides access to information not previously available in standard SERS. We summarize the rich plasmonic physics at work in these extended systems and highlight the recent state of the art including tip-enhanced Raman spectroscopy (TERS) and the application of mechanical break junctions and electromigrated junctions. We describe in detail how we have performed in situ gap-enhanced Raman measurements of molecular-scale junctions while simultaneously subjecting these structures to electronic transport. These extended electrode structures allow us to study the pumping of vibrational modes by the flow of tunneling electrons, as well as the shifting of vibrational energies due to the applied bias. These experiments extend SERS into a tool for examining fundamental processes of dissipation, and provide insight into the mechanisms behind SERS spectral diffusion. We conclude with a brief discussion of future directions. PMID:23385304

  17. Coherent and spontaneous Raman spectroscopy in shocked and unshocked liquids

    SciTech Connect

    Schmidt, S.C.; Moore, D.S.; Schiferl, D.; Chatelet, M.; Turner, T.P.; Shaner, J.W.; Shampine, D.L.; Holt, W.T.

    1985-01-01

    Coherent and non-coherent Raman spectroscopy is being used to study the structure and energy transfer in molecular liquids at high pressures. Stimulated Raman scattering, coherent anti-Stokes Raman scattering, and Raman induced Kerr effect scattering measurements have been performed in liquid benzene and liquid nitromethane shocked to pressures up to 11 GPa. Frequency shifts were observed for the 992 cm/sup -1/ ring stretching mode of benzene and the 920 cm/sup -1/ CN stretching mode of nitromethane. Results of these dynamic experiments are compared to spontaneous Raman scattering measurements made in a high temperature diamond anvil cell. Also, a picosecond infrared pump/spontaneous anti-Strokes Raman probe experiment is being used to measure CH stretch vibrational relaxation times in liquid halogenated methanes statically compressed to a few tenths GPa. 87 refs., 17 figs.

  18. Micro-Raman spectroscopy on oral tissues

    NASA Astrophysics Data System (ADS)

    Zenone, F.; Lepore, M.; Perna, G.; Carmone, P.; Riccio, R.; Gaeta, G. M.; Capozzi, V.

    2006-02-01

    Micro-Raman Spectroscopy (μ-RS) provides a unique tool in medicine for a not invasive and real time analysis of biological tissue for biopsy and "in vivo" investigation. Based on the evaluation of molecular vibration frequencies, the μ-RS is able to detect the main molecular bonds of protein constituents, as the C-H and C-C ones. Changes in frequency or in the relative intensity of the vibration modes revealed by μ-RS can be related to changes of chemical bond and of protein structure induced by pathology. The μ-RS has been performed on samples of oral tissue from informed patients, affected by pemphigus vulgaris (an oral pathology) in an advanced regression state. The biopsies were thin slices (about 1mm thick) with 6mm diameter. The sample was measured through a 170 μm thick cover-glass. The experimental set-up was mainly composed by a He-Ne laser and a monochromator equipped with a Peltier cell and with a grating of 1800 grooves/mm. The laser light was focused on the sample surface by means of a long focal length 50X optical objective. The main protein bonds are clearly detectable in the considered samples and this give important information on the integrity and on the state of tissue components (lipids and proteins), and consequently on the occurrence of pathology. The potential application of this method for in vivo analysis is an invaluable alternative to biopsy and pathological examinations for many medical application as screening diagnostic, therapy progress examination, and surgical support.

  19. Raman and surface-enhanced Raman spectroscopy for renal condition monitoring

    NASA Astrophysics Data System (ADS)

    Li, Jingting; Li, Ming; Du, Yong; Santos, Greggy M.; Mohan, Chandra; Shih, Wei-Chuan

    2016-03-01

    Non- and minimally-invasive techniques can provide advantages in the monitoring and clinical diagnostics in renal diseases. Although renal biopsy may be useful in establishing diagnosis in several diseases, it is an invasive approach and impractical for longitudinal disease monitoring. To address this unmet need, we have developed two techniques based on Raman spectroscopy. First, we have investigated the potential of diagnosing and staging nephritis by analyzing kidney tissue Raman spectra using multivariate techniques. Secondly, we have developed a urine creatinine sensor based on surface-enhanced Raman spectroscopy with performance near commercial assays which require relatively laborious sample preparation and longer time.

  20. Ultrafast and nonlinear surface-enhanced Raman spectroscopy.

    PubMed

    Gruenke, Natalie L; Cardinal, M Fernanda; McAnally, Michael O; Frontiera, Renee R; Schatz, George C; Van Duyne, Richard P

    2016-04-21

    Ultrafast surface-enhanced Raman spectroscopy (SERS) has the potential to study molecular dynamics near plasmonic surfaces to better understand plasmon-mediated chemical reactions such as plasmonically-enhanced photocatalytic or photovoltaic processes. This review discusses the combination of ultrafast Raman spectroscopic techniques with plasmonic substrates for high temporal resolution, high sensitivity, and high spatial resolution vibrational spectroscopy. First, we introduce background information relevant to ultrafast SERS: the mechanisms of surface enhancement in Raman scattering, the characterization of plasmonic materials with ultrafast techniques, and early complementary techniques to study molecule-plasmon interactions. We then discuss recent advances in surface-enhanced Raman spectroscopies with ultrafast pulses with a focus on the study of molecule-plasmon coupling and molecular dynamics with high sensitivity. We also highlight the challenges faced by this field by the potential damage caused by concentrated, highly energetic pulsed fields in plasmonic hotspots, and finally the potential for future ultrafast SERS studies. PMID:26848784

  1. Raman spectroscopy for label-free identification of calciphylaxis.

    PubMed

    Lloyd, William R; Agarwal, Shailesh; Nigwekar, Sagar U; Esmonde-White, Karen; Loder, Shawn; Fagan, Shawn; Goverman, Jeremy; Olsen, Bjorn R; Jumlongras, Dolrudee; Morris, Michael D; Levi, Benjamin

    2015-08-01

    Calciphylaxis is a painful, debilitating, and premorbid condition, which presents as calcified vasculature and soft tissues. Traditional diagnosis of calciphylaxis lesions requires an invasive biopsy, which is destructive, time consuming, and often leads to exacerbation of the condition and infection. Furthermore, it is difficult to find small calcifications within a large wound bed. To address this need, a noninvasive diagnostic tool may help clinicians identify ectopic calcified mineral and determine the disease margin. We propose Raman spectroscopy as a rapid, point-of-care, noninvasive, and label-free technology to detect calciphylaxis mineral. Debrided calciphylactic tissue was collected from six patients and assessed by microcomputed tomography (micro-CT). Micro-CT confirmed extensive deposits in three specimens, which were subsequently examined with Raman spectroscopy. Raman spectra confirmed that deposits were consistent with carbonated apatite, consistent with the literature. Raman spectroscopy shows potential as a noninvasive technique to detect calciphylaxis in a clinical environment. PMID:26263412

  2. Raman spectroscopy for label-free identification of calciphylaxis

    PubMed Central

    Lloyd, William R.; Agarwal, Shailesh; Nigwekar, Sagar U.; Esmonde-White, Karen; Loder, Shawn; Fagan, Shawn; Goverman, Jeremy; Olsen, Bjorn R.; Jumlongras, Dolrudee; Morris, Michael D.; Levi, Benjamin

    2015-01-01

    Abstract. Calciphylaxis is a painful, debilitating, and premorbid condition, which presents as calcified vasculature and soft tissues. Traditional diagnosis of calciphylaxis lesions requires an invasive biopsy, which is destructive, time consuming, and often leads to exacerbation of the condition and infection. Furthermore, it is difficult to find small calcifications within a large wound bed. To address this need, a noninvasive diagnostic tool may help clinicians identify ectopic calcified mineral and determine the disease margin. We propose Raman spectroscopy as a rapid, point-of-care, noninvasive, and label-free technology to detect calciphylaxis mineral. Debrided calciphylactic tissue was collected from six patients and assessed by microcomputed tomography (micro-CT). Micro-CT confirmed extensive deposits in three specimens, which were subsequently examined with Raman spectroscopy. Raman spectra confirmed that deposits were consistent with carbonated apatite, consistent with the literature. Raman spectroscopy shows potential as a noninvasive technique to detect calciphylaxis in a clinical environment. PMID:26263412

  3. Phenotypic Profiling of Antibiotic Response Signatures in Escherichia coli Using Raman Spectroscopy

    PubMed Central

    Athamneh, A. I. M.; Alajlouni, R. A.; Wallace, R. S.; Seleem, M. N.

    2014-01-01

    Identifying the mechanism of action of new potential antibiotics is a necessary but time-consuming and costly process. Phenotypic profiling has been utilized effectively to facilitate the discovery of the mechanism of action and molecular targets of uncharacterized drugs. In this research, Raman spectroscopy was used to profile the phenotypic response of Escherichia coli to applied antibiotics. The use of Raman spectroscopy is advantageous because it is noninvasive, label free, and prone to automation, and its results can be obtained in real time. In this research, E. coli cultures were subjected to three times the MICs of 15 different antibiotics (representing five functional antibiotic classes) with known mechanisms of action for 30 min before being analyzed by Raman spectroscopy (using a 532-nm excitation wavelength). The resulting Raman spectra contained sufficient biochemical information to distinguish between profiles induced by individual antibiotics belonging to the same class. The collected spectral data were used to build a discriminant analysis model that identified the effects of unknown antibiotic compounds on the phenotype of E. coli cultures. Chemometric analysis showed the ability of Raman spectroscopy to predict the functional class of an unknown antibiotic and to identify individual antibiotics that elicit similar phenotypic responses. Results of this research demonstrate the power of Raman spectroscopy as a cellular phenotypic profiling methodology and its potential impact on antibiotic drug development research. PMID:24295982

  4. Applications of Fourier transform Raman and infrared spectroscopy in forensic sciences

    NASA Astrophysics Data System (ADS)

    Kuptsov, Albert N.

    2000-02-01

    First in the world literature comprehensive digital complementary vibrational spectra collection of polymer materials and search system was developed. Non-destructive combined analysis using complementary FT-Raman and FTIR spectra followed by cross-parallel searching on digital spectral libraries, was applied in different fields of forensic sciences. Some unique possibilities of Raman spectroscopy has been shown in the fields of examination of questioned documents, paper, paints, polymer materials, gemstones and other physical evidences.

  5. In situ cell cycle phase determination using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Oshima, Yusuke; Takenaka, Tatsuji; Sato, Hidetoshi; Furihata, Chie

    2010-02-01

    Raman spectroscopy is a powerful tool for analysis of the chemical composition in living tissue and cells without destructive processes such as fixation, immunostaining, and fluorescence labeling. Raman microspectroscopic technique enables us to obtain a high quality spectrum from a single living cell. We demonstrated in situ cell cycle analysis with Raman microspectroscopy with the excitation wavelength of 532 nm. Cell cycle phases, G0/G1 and G2/M were able to be identified in the present study. The result of in situ Raman analysis was evaluated with flow cytometry analysis. Although the Raman spectra of living cells showed complex patterns during cell cycle, several Raman bands could be useful as markers for the cell cycle identification. A single cell analysis using Raman microspectroscopy predicted a possibility to observe directly molecular dynamics intracellular molecules of proteins, lipids and nucleic acids. Our current study focused on cytoplasm region and resonant Raman signals of cytochrome c in mitochondrion, and discussed how the Raman signals from cellular components contribute to the Raman spectral changes in cell cycle change in the human living cell (lung cancer cell).

  6. [Fast discrimination of edible vegetable oil based on Raman spectroscopy].

    PubMed

    Zhou, Xiu-Jun; Dai, Lian-Kui; Li, Sheng

    2012-07-01

    A novel method to fast discriminate edible vegetable oils by Raman spectroscopy is presented. The training set is composed of different edible vegetable oils with known classes. Based on their original Raman spectra, baseline correction and normalization were applied to obtain standard spectra. Two characteristic peaks describing the unsaturated degree of vegetable oil were selected as feature vectors; then the centers of all classes were calculated. For an edible vegetable oil with unknown class, the same pretreatment and feature extraction methods were used. The Euclidian distances between the feature vector of the unknown sample and the center of each class were calculated, and the class of the unknown sample was finally determined by the minimum distance. For 43 edible vegetable oil samples from seven different classes, experimental results show that the clustering effect of each class was more obvious and the class distance was much larger with the new feature extraction method compared with PCA. The above classification model can be applied to discriminate unknown edible vegetable oils rapidly and accurately. PMID:23016334

  7. Application of Raman spectroscopy technology to studying Sudan I

    NASA Astrophysics Data System (ADS)

    Li, Gang; Zhang, Guoping; Chen, Chen

    2006-06-01

    Being an industrial dye, the Sudan I may have a toxic effect after oral intake on the body, and has recently been shown to cause cancer in rats, mice and rabbits. Because China and some other countries have detected the Sudan I in samples of the hot chilli powder and the chilli products, it is necessary to study the characteristics of this dye. As one kind of molecule scattering spectroscopy, Raman spectroscopy is characterized by the frequency excursion caused by interactions of molecules and photons. The frequency excursion reflects the margin between certain two vibrational or rotational energy states, and shows the information of the molecule. Because Raman spectroscopy can provides quick, easy, reproducible, and non-destructive analysis, both qualitative and quantitative, with no sample preparation required, Raman spectroscopy has been a particularly promising technique for analyzing the characteristics and structures of molecules, especially organic ones. Now, it has a broad application in biological, chemical, environmental and industrial applications. This paper firstly introduces Sudan I dye and the Raman spectroscopy technology, and then describes its application to the Sudan I. Secondly, the fingerprint spectra of the Sudan I are respectively assigned and analyzed in detail. Finally, the conclusion that the Raman spectroscopy technology is a powerful tool to determine the Sudan I is drawn.

  8. Applications of Raman scattering spectroscopy to halide glasses

    NASA Astrophysics Data System (ADS)

    Bendow, B.; Banerjee, P. K.; Drexhage, M. G.

    1983-04-01

    Polarized Raman scattering spectroscopy is a useful tool for investigating fundamental vibrational properties, structure and bonding, origins of IR edge absorption, and dispersion of the IR refractive index. In this paper, the application of Raman spectroscopy to halide glasses and, in particular, heavy metal fluoride glasses, is described. The spectra of the latter differ substantially from those of simple oxide, halide or chalcogenide glasses and, moreover, display a wide range of vibrational characteristics, depending on composition. In combination with infrared spectroscopy, useful guidelines can be developed for tailoring glass compositions for specific applications.

  9. Raman spectroscopy of carboranes and polycarboranesiloxanes

    SciTech Connect

    Shelnutt, J.A.

    1986-01-01

    Raman spectra of some m-carboranesiloxane polymers are compared with each other and with the spectrum of o-carborane and boron carbide. The comparisons and additional polarization studies allow the assignment of some vibrations to the icosahedral 1,7-dicarboranyl units, siloxy polymer connecting units, and substituent groups of the silicon atoms. The Raman investigation is directed toward understanding the interaction of carborane icosahedral units of boron-carbide semiconductor materials.

  10. Raman spectroscopy of fluoropolymer conformal coatings on electronic boards

    NASA Astrophysics Data System (ADS)

    Rodošek, Mirjana; Perše, Lidija Slemenik; Mihelčič, Mohor; Koželj, Matjaž; Orel, Boris; Bengű, Başak; Sunetci, Onder; Pori, Pauli; Vuk, Angela Šurca

    2014-09-01

    Fluoropolymer conformal coatings were applied to electronic boards (EBs) and cured at room temperature or 80°C. The coatings were first deposited on model substrate, i.e. aluminium alloy AA 2024 and tested for their anticorrosion properties with a potentiodynamic polarisation technique. The cathodic current densities ranged from 10-9-10-10 A/cm2, approaching the lower current limit after the addition of TiO2 nanoparticles into the formulation. Application of fluoropolymer-based formulation was performed via spray-coating deposition. Examination of the coverage of EBs under UV light, which is commonly used in industry, revealed that some components might not be entirely covered. In the search for other possible analytical tools of coverage with protective coatings, optical microscopy and confocal Raman spectroscopy were investigated.

  11. Study of spin-ordering and spin-reorientation transitions in hexagonal manganites through Raman spectroscopy

    PubMed Central

    Chen, Xiang-Bai; Hien, Nguyen Thi Minh; Han, Kiok; Nam, Ji-Yeon; Huyen, Nguyen Thi; Shin, Seong-Il; Wang, Xueyun; Cheong, S. W.; Lee, D.; Noh, T. W.; Sung, N. H.; Cho, B. K.; Yang, In-Sang

    2015-01-01

    Spin-wave (magnon) scattering, when clearly observed by Raman spectroscopy, can be simple and powerful for studying magnetic phase transitions. In this paper, we present how to observe magnon scattering clearly by Raman spectroscopy, then apply the Raman method to study spin-ordering and spin-reorientation transitions of hexagonal manganite single crystal and thin films and compare directly with the results of magnetization measurements. Our results show that by choosing strong resonance condition and appropriate polarization configuration, magnon scattering can be clearly observed, and the temperature dependence of magnon scattering can be simple and powerful quantity for investigating spin-ordering as well as spin-reorientation transitions. Especially, the Raman method would be very helpful for investigating the weak spin-reorientation transitions by selectively probing the magnons in the Mn3+ sublattices, while leaving out the strong effects of paramagnetic moments of the rare earth ions. PMID:26300075

  12. Study of spin-ordering and spin-reorientation transitions in hexagonal manganites through Raman spectroscopy.

    PubMed

    Chen, Xiang-Bai; Hien, Nguyen Thi Minh; Han, Kiok; Nam, Ji-Yeon; Huyen, Nguyen Thi; Shin, Seong-Il; Wang, Xueyun; Cheong, S W; Lee, D; Noh, T W; Sung, N H; Cho, B K; Yang, In-Sang

    2015-01-01

    Spin-wave (magnon) scattering, when clearly observed by Raman spectroscopy, can be simple and powerful for studying magnetic phase transitions. In this paper, we present how to observe magnon scattering clearly by Raman spectroscopy, then apply the Raman method to study spin-ordering and spin-reorientation transitions of hexagonal manganite single crystal and thin films and compare directly with the results of magnetization measurements. Our results show that by choosing strong resonance condition and appropriate polarization configuration, magnon scattering can be clearly observed, and the temperature dependence of magnon scattering can be simple and powerful quantity for investigating spin-ordering as well as spin-reorientation transitions. Especially, the Raman method would be very helpful for investigating the weak spin-reorientation transitions by selectively probing the magnons in the Mn(3+) sublattices, while leaving out the strong effects of paramagnetic moments of the rare earth ions. PMID:26300075

  13. Tip-enhanced Raman spectroscopy and near-field polarization

    NASA Astrophysics Data System (ADS)

    Saito, Yuika; Mino, Toshihiro; Verma, Prabhat

    2015-12-01

    Tip-enhanced Raman spectroscopy (TERS) is a powerful tool for High-resolution Raman spectroscopy. In this method, a metal coated nano-tip acts as a plasmonic antenna to enhance the originally weak Raman scattering from a nanometric volume of a sample. The technique enables to detect Raman scattering light from nano-scale area and also enhance the light intensity with combination of near-filed light and localized surface plasmon generated at a metallized tip apex. Nowadays TERS is used to investigate various nano-scale samples, for examples, carbon nanotubes, graphenes DNA and biomaterials. As the TERS developed, there is high demand to investigate the properties of near-field light e.g. polarization properties. We have analyzed the polarization properties of near-field light in TERS and successfully realized the quantitative nano-imaging by visible light.

  14. Raman and Infrared Spectroscopy of Pyridine under High Pressure

    SciTech Connect

    Zhuravlev, K.; Traikov, K; Dong, Z; Xie, S; Song, Y; Liu, Z

    2010-01-01

    We report the structural transitions of pyridine as a function of pressure up to 26 GPa using in situ Raman spectroscopy and infrared absorption spectroscopy. By monitoring changes in the Raman shifts in the lattice region as well as the band profiles in both Raman and IR spectra, a liquid-to-solid transition at 1 GPa followed by solid-to-solid transitions at 2, 8, 11, and 16 GPa were observed upon compression. These transitions were found to be reversible upon decompression from 22 GPa. A further chemical transformation was observed when compressed beyond 22 GPa as evidenced by the substantial and irreversible changes in the Raman and infrared spectra, which could be attributed to the destruction of the ring structure. The observed transformations in pyridine were also compared to those for benzene. The similar transition sequence with well-aligned transition pressures suggests that these isoelectronic aromatics may have similar structures and stabilities under high pressure.

  15. Remote cure monitoring of polymeric resins by laser Raman spectroscopy

    SciTech Connect

    Hong, K.C.; Vess, T.M.; Lyon, R.E.; Myrick, M.L.

    1993-05-01

    The validity of using Raman spectroscopy to monitor the cure chemistries of amine-cured epoxy is demonstrated by correlating NIR absorbance measurements with Raman measurements for a concentration series of bisphenol-A diglycidylether in its own reaction product with diethylamine. The intensity of a normalized Raman peak at 1240 cm{sup {minus}l}, assigned to the epoxide functionality, was found to be linearly related to the concentration of epoxide groups in the resin mixtures. Also, it is shown that the Ciba-Geigy Matrimid 5292 system can be monitored by ex-situ FT-Raman spectroscopy by observing changes in the carbonyl stretching (1773 cm{sup {minus}1}) or the C=C stretching of maleimide (1587 cm{sup {minus}1}) during the cure reaction.

  16. Monitoring the influence of antibiotic exposure using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Samek, Ota; Zemanek, Pavel; Bernatova, Silvie; Jezek, Jan; Sery, Mojmir; Jakl, Petr; Siler, Martin; Ruzicka, Filip

    2014-03-01

    Here we report on combination of the data obtained from MICs (minimum inhibitory concentrations) with infor- mation of microoragnisms fingerprint provided by Raman spectroscopy. In our feasibility study we could follow mechanisms of the bacteriostatic versus bactericidal action on biofilm-positive Staphylococcus epidermidis simply by monitoring Raman bands corresponding to DNA translating the changes introduced by selected antibiotics. The Raman spectra of Staphylococcus epidermidis treated with a bacteriostatic agent show little effect on DNA which is in contrast with the action of a bactericidal agent where decreased in dedicated Raman spectra signal strength suggests DNA fragmentation. Moreover, we demonstrate that Raman tweezers are indeed able to distinguish strains of biofilm-forming (biofilm-positive) and biofilm-negative Staphylococcus epidermidis strains using principal component analysis (PCA).

  17. Proximal and point detection of contaminated surfaces using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason A.; Christesen, Steven D.; Tripathi, Ashish; Emmons, Erik D.; Wilcox, Phillip G.; Emge, Darren K.; Pardoe, Ian J.; Fountain, Augustus W., III

    2011-11-01

    We are actively investigating the use of Raman spectroscopy for proximal standoff detection of chemicals and explosive materials on surfaces. These studies include Raman Chemical Imaging of contaminated fingerprints for forensic attribution and the assessments of commercial handheld or portable Raman instruments operating with near-infrared (IR) as well as ultraviolet (UV) laser excitation specifically developed for on-the-move reconnaissance of chemical contamination. As part of these efforts, we have measured the Raman cross sections of chemical agents, toxic industrial chemicals, and explosives from the UV to NIR. We have also measured and modeled the effect interrogation angle has on the Raman return from droplets on man-made surfaces. Realistic droplet distributions have been modeled and tested against variations in surface scan patterns and laser spot size for determining the optimum scan characteristics for detection of relevant surface contamination.

  18. Single bacteria identification by Raman spectroscopy.

    PubMed

    Strola, Samy Andrea; Baritaux, Jean-Charles; Schultz, Emmanuelle; Simon, Anne Catherine; Allier, Cédric; Espagnon, Isabelle; Jary, Dorothée; Dinten, Jean-Marc

    2014-01-01

    We report on rapid identification of single bacteria using a low-cost, compact, Raman spectroscope. We demonstrate that a 60-s procedure is sufficient to acquire a comprehensive Raman spectrum in the range of 600 to 3300 cm⁻¹. This time includes localization of small bacteria aggregates, alignment on a single individual, and spontaneous Raman scattering signal collection. Fast localization of small bacteria aggregates, typically composed of less than a dozen individuals, is achieved by lensfree imaging over a large field of view of 24 mm². The lensfree image also allows precise alignment of a single bacteria with the probing beam without the need for a standard microscope. Raman scattered light from a 34-mW continuous laser at 532 nm was fed to a customized spectrometer (prototype Tornado Spectral Systems). Owing to the high light throughput of this spectrometer, integration times as low as 10 s were found acceptable. We have recorded a total of 1200 spectra over seven bacterial species. Using this database and an optimized preprocessing, classification rates of ~90% were obtained. The speed and sensitivity of our Raman spectrometer pave the way for high-throughput and nondestructive real-time bacteria identification assays. This compact and low-cost technology can benefit biomedical, clinical diagnostic, and environmental applications. PMID:25028774

  19. Single Molecule Raman Spectroscopy Under High Pressure

    NASA Astrophysics Data System (ADS)

    Fu, Yuanxi; Dlott, Dana

    2014-06-01

    Pressure effects on surface-enhanced Raman scattering spectra of Rhdoamine 6G adsorbed on silver nanoparticle surfaces was studied using a confocal Raman microscope. Colloidal silver nanoparticles were treated with Rhodamine 6G (R6G) and its isotopically substituted partner, R6G-d4. Mixed isotopomers let us identify single-molecule spectra, since multiple-molecule spectra would show vibrational transitions from both species. The nanoparticles were embedded into a poly vinyl alcohol film, and loaded into a diamond anvil cell for the high-pressure Raman scattering measurement. Argon was the pressure medium. Ambient pressure Raman scattering spectra showed few single-molecule spectra. At moderately high pressure ( 1GPa), a surprising effect was observed. The number of sites with observable spectra decreased dramatically, and most of the spectra that could be observed were due to single molecules. The effects of high pressure suppressed the multiple-molecule Raman sites, leaving only the single-molecule sites to be observed.

  20. Identification and discrimination of polycyclic aromatic hydrocarbons using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Cloutis, Edward; Szymanski, Paul; Applin, Daniel; Goltz, Douglas

    2016-08-01

    Polycyclic aromatic hydrocarbons (PAHs) are widely present throughout the Solar System and beyond. They have been implicated as a contributor to unidentified infrared emission bands in the interstellar medium, comprise a substantial portion of the insoluble organic matter in carbonaceous chondrites, are expected stable components of organic matter on Mars, and are present in a wide range of terrestrial hydrocarbons and as components of biomolecules. However, PAH structures can be very complicated, making their identification challenging. Raman spectroscopy is known to be especially sensitive to the highly polarizable C-C and C=C bonds found in PAHs, and therefore, can be a powerful tool for PAH structural and compositional elucidation. This study examined Raman spectra of 48 different PAHs to determine the degree to which Raman spectroscopy could be used to uniquely identify different species, factors that control the positions of major Raman peaks, the degree to which induced fluorescence affects the intensity of Raman peaks, its usefulness for PAH discrimination, and the effects of varying excitation wavelength on some PAH Raman spectra. It was found that the arrangement and composition of phenyl (benzene) rings, and the type and position of functional groups can greatly affect fluorescence, positions and intensities of Raman peaks associated with the PAH backbone, and the introduction of new Raman peaks. Among the functional groups found on many of the PAHs that were analyzed, only a few Raman peaks corresponding to the molecular vibrations of these groups could be clearly distinguished. Comparison of the PAH Raman spectra that were acquired with both 532 and 785 nm excitation found that the longer wavelength resulted in reduced fluorescence, consistent with previous studies.

  1. Raman Spectroscopy Analysis Of Mechanical Stress Near Cu-TSVs

    NASA Astrophysics Data System (ADS)

    De Wolf, Ingrid

    2011-09-01

    This paper discusses Raman spectroscopy measurements of stress near Cu-TSVs (Through Silicon Vias) used in 3D stacking of thinned chips. It discusses the resolution and penetration depth of the technique and the relation between the measured Raman shift and stress. Using a simple model, the various stress components near TSVs are discussed and the relation between the measured Raman shift and these stress components is analyzed. Results obtained on TSVs with nearby shallow-trench isolation, with different Cu chemistry, with and without SiO2 layer on top, and with different aspect ratio are discussed and analyzed using the simple model.

  2. Pharmaceutical Analysis from Start to Finish by Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Donahue, Michael; Smith, Wayne; Patient, Michael; Farquharson, Stuart

    2010-08-01

    During the past decade Raman spectroscopy has become a widely used analytical tool in the laboratory, process environment and on-line. This is largely due to the fact that virtually every chemical produces a unique Raman signature, sample preparation is generally not required, and analyses can be performed in 1 minute or less. This presentation will describe the value of fluorescent free and x-axis stable Raman spectra in confirming the identity of raw materials, tracking reaction kinetics during drug discovery and product synthesis, monitoring and controlling batch and continuous feed reactors, and determining product properties using chemometrics.

  3. Raman spectroscopy of polyhedral carbon nano-onions

    NASA Astrophysics Data System (ADS)

    Codorniu Pujals, Daniel; Arias de Fuentes, Olimpia; Desdín García, Luis F.; Cazzanelli, Enzo; Caputi, Lorenzo S.

    2015-09-01

    The Raman spectra of polyhedral carbon nano-onions (PCO), obtained by underwater arc discharge of graphite electrodes, are studied. While the general Raman spectrum of PCO is very similar to those of other carbon nanostructures, including spherical nano-onions, the fine structure of the G and 2D bands gives valuable information that allows using Raman spectroscopy for differentiating the PCO from other carbon structures. The interpretation of the features of the fine structure of the spectra is supported by evidences obtained by TEM.

  4. Raman spectroscopy of blood in-vitro

    NASA Astrophysics Data System (ADS)

    Villanueva-Luna, A. E.; Castro-Ramos, J.; Vazquez-Montiel, S.; Flores-Gil, A.; Ortiz-Lima, C. M.; Delgado-Atencio, J. A.

    2012-03-01

    We present Raman spectra from a sample of 8 volunteers that have different type of blood. The experimental data were carried out using a 785 nm excitation laser and an ocean optics spectrometer of 6 cm-1 resolution, with a used spectral region from 1000 to 1800 cm-1. We find Raman features at 1000 and 1542 cm-1 regarded with hemoglobin and its derivatives. Also we find Raman features at 1248 and 1342 cm-1 that are now regarded with pure fibrin. In this work, we use Principal Component analysis (PCA) to determine all variations of our samples, which allows us to define a classification of the influence of the blood type. Finally, we found vibrational lines of cholesterol, glucose and triglycerides that are reported in literature.

  5. Raman spectroscopy of vapors at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Laane, Jaan; Haller, Kristjan; Sakurai, Sachie; Morris, Kevin; Autrey, Daniel; Arp, Zane; Chiang, Whe-Yi; Combs, Amanda

    2003-05-01

    The most effective way to obtain high quality vapor-phase Raman spectra is to heat the samples to increase their vapor pressure. Many samples can be heated to 350 °C and higher without decomposition. We have designed a simple Raman cell to allow these high temperature studies to be carried out. The high-temperature Raman spectra of nine molecules will be presented and discussed. Most of these are non-rigid molecules containing aromatic rings for which vibrational potential energy surfaces have been determined from their spectra. Two molecules ( p-cresol and 3-methylindole) are model compounds for amino acids and their vapor-phase spectra are characteristic of environments with no hydrogen bonding.

  6. Differentiation of lipsticks by Raman spectroscopy.

    PubMed

    Salahioglu, Fatma; Went, Michael J

    2012-11-30

    Dispersive Raman spectra have been obtained using a Raman microscope and an excitation wavelength of 632.8 nm from 69 lipsticks of various colours and from a range of manufacturers without any pre-treatment of the samples. 10% of the samples were too fluorescent to give Raman spectra. 22% of the samples gave spectra which were unique to the brand and colour within the collected sample set. The remaining 68% of the samples gave spectra which could be classified into seven distinct groups. Discrimination of red lipsticks by this technique was the most difficult. The spectra of deposited lipstick samples remained unchanged over a period of a least a year. PMID:22959771

  7. Detection of Sphingomyelin Clusters by Raman Spectroscopy.

    PubMed

    Shirota, Koichiro; Yagi, Kiyoshi; Inaba, Takehiko; Li, Pai-Chi; Murata, Michio; Sugita, Yuji; Kobayashi, Toshihide

    2016-09-01

    Sphingomyelin (SM) is a major sphingolipid in mammalian cells that forms specific lipid domains in combination with cholesterol (Chol). Using molecular-dynamics simulation and density functional theory calculation, we identified a characteristic Raman band of SM at ∼1643 cm(-1) as amide I of the SM cluster. Experimental results indicate that this band is sensitive to the hydration of SM and the presence of Chol. We showed that this amide I Raman band can be utilized to examine the membrane distribution of SM. Similarly to SM, ceramide phosphoethanolamine (CerPE) exhibited an amide I Raman band in almost the same region, although CerPE lacks three methyl groups in the phosphocholine moiety of SM. In contrast to SM, the amide I band of CerPE was not affected by Chol, suggesting the importance of the methyl groups of SM in the SM-Chol interaction. PMID:27602727

  8. Power Budget Analysis for Waveguide-Enhanced Raman Spectroscopy.

    PubMed

    Wang, Zilong; Pearce, Stuart J; Lin, Yung-Chun; Zervas, Michalis N; Bartlett, Philip N; Wilkinson, James S

    2016-08-01

    Waveguide-enhanced Raman spectroscopy (WERS) is emerging as an attractive alternative to plasmonic surface-enhanced Raman spectroscopy approaches as it can provide more reproducible quantitative spectra on a robust chip without the need for nanostructured plasmonic materials. Realizing portable WERS systems with high sensitivity using low-cost laser diodes and compact spectrometers requires a detailed analysis of the power budget from laser to spectrometer chip. In this paper, we describe theoretical optimization of planar waveguides for maximum Raman excitation efficiency, demonstrate WERS for toluene on a silicon process compatible high index contrast tantalum pentoxide waveguide, measure the absolute conversion efficiency from pump power to received power in an individual Raman line, and compare this with a power budget analysis of the complete system including collection with an optical fiber and interfacing to a compact spectrometer. Optimized 110 nm thick Ta2O5 waveguides on silica substrates excited at a wavelength of 637 nm are shown experimentally to yield overall system power conversion efficiency of ∼0.5 × 10(-12) from the pump power in the waveguide to the collected Raman power in the 1002 cm(-1) Raman line of toluene, in comparison with a calculated efficiency of 3.9 × 10(-12) Collection efficiency is dictated by the numerical and physical apertures of the spectral detection system but may be improved by further engineering the spatial and angular Raman scattering distributions. PMID:27301326

  9. Sensitive algorithm for multiple-excitation-wavelength resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yellampalle, Balakishore; Wu, Hai-Shan; McCormick, William; Sluch, Mikhail; Martin, Robert; Ice, Robert; Lemoff, Brian E.

    2014-05-01

    Raman spectroscopy is a widely used spectroscopic technique with a number of applications. During the past few years, we explored the use of simultaneous multiple-excitation-wavelengths (MEW) in resonance Raman spectroscopy. This approach takes advantage of Raman band intensity variations across the Resonance Raman spectra obtained from two or more excitation wavelengths. Amplitude variations occur between corresponding Raman bands in Resonance Raman spectra due to complex interplay of resonant enhancement, self-absorption and laser penetration depth. We have developed a very sensitive algorithm to estimate concentration of an analyte from spectra obtained using the MEW technique. The algorithm uses correlations and least-square minimization approach to calculate an estimate for the concentration. For two or more excitation wavelengths, measured spectra were stacked in a two dimensional matrix. In a simple realization of the algorithm, we approximated peaks in the ideal library spectra as triangles. In this work, we present the performance of the algorithm with measurements obtained from a dual-excitation-wavelength Resonance Raman sensor. The novel sensor, developed at WVHTCF, detects explosives from a standoff distance. The algorithm was able to detect explosives with very high sensitivity even at signal-to-noise ratios as low as ~1.6. Receiver operating characteristics calculated using the algorithm showed a clear benefit in using the dual-excitation-wavelength technique over single-excitation-wavelength techniques. Variants of the algorithm that add more weight to amplitude variation information showed improved specificity to closely resembling spectra.

  10. Fiber-optic Raman Spectroscopy of Joint Tissues

    PubMed Central

    Esmonde-White, Karen A.; Esmonde-White, Francis W.L.; Morris, Michael D.

    2011-01-01

    In this study, we report adaptation of Raman spectroscopy for arthroscopy of joint tissues using a custom-built fiber optic probe. Differentiation of healthy and damaged tissue or examination of subsurface tissue, such as subchondral bone, is a challenge in arthroscopy because visual inspection may not provide sufficient contrast. Discrimination of healthy versus damaged tissue may be improved by incorporating point spectroscopy or hyperspectral imaging into arthroscopy where contrast is based on molecular structure or chemical composition. Articular joint surfaces of knee cadaveric human tissue and tissue phantoms were examined using a custom-designed Raman fiber optic probe. Fiber-optic Raman spectra were compared against reference spectra of cartilage, subchondral bone and cancellous bone collected using Raman microspectroscopy. In fiber-optic Raman spectra of the articular surface, there was an effect of cartilage thickness on recovery of signal from subchondral bone. At sites with intact cartilage, the bone mineralization ratio decreased but there was a minimal effect in the bone mineral chemistry ratios. Tissue phantoms were prepared as experimental models of the osteochondral interface. Raman spectra of tissue phantoms suggested that optical scattering of cartilage has a large effect on the relative cartilage and bone signal. Finite element analysis modeling of light fluence in the osteochondral interface confirmed experimental findings in human cadaveric tissue and tissue phantoms. These first studies demonstrate proof of principle for Raman arthroscopic measurement of joint tissues and provide a basis for future clinical or animal model studies. PMID:21359366

  11. Surface and waveguide collection of Raman emission in waveguide-enhanced Raman spectroscopy.

    PubMed

    Wang, Zilong; Zervas, Michalis N; Bartlett, Philip N; Wilkinson, James S

    2016-09-01

    We demonstrate Raman spectroscopy on a high index thin film tantalum pentoxide waveguide and compare collection of Raman emission from the waveguide end with that from the waveguide surface. Toluene was used as a convenient model analyte, and a 40-fold greater signal was collected from the waveguide end. Simulations of angular and spatial Raman emission distributions showed good agreement with experiments, with the enhancement resulting from efficient collection of power from dipoles near the surface into the high-index waveguide film and substrate, combined with long interaction length. The waveguide employed was optimized at the excitation wavelength but not at emission wavelengths, and full optimization is expected to lead to enhancements comparable to surface-enhanced Raman spectroscopy in robust low-cost metal-free and nanostructure-free chips. PMID:27607994

  12. The substrate matters in the Raman spectroscopy analysis of cells

    NASA Astrophysics Data System (ADS)

    Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R. T.

    2015-08-01

    Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research.

  13. The substrate matters in the Raman spectroscopy analysis of cells

    PubMed Central

    Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R.T.

    2015-01-01

    Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research. PMID:26310910

  14. Dengue blood analysis by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rehman, A.; Anwar, S.; Firdous, S.; Ahmed, M.; Rasheed, R.; Nawaz, M.

    2012-06-01

    In this work Raman spectra of normal and dengue infected serum and whole blood were analyzed. In normal whole blood and serum characteristic peaks were observed when excited at 442 and 532 nm. In dengue whole blood and serum all peaks found to be blue shifted with reduced Raman intensity. Dengue whole blood and serum shows two peaks at 1614 and 1750 cm-1 which are due to presence of Immunoglobulin antibodies IgG and IgM. Whole study provides a route of information for diagnosis of dengue viral infection.

  15. Metallized Capillaries as Probes for Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Pelletier, Michael

    2003-01-01

    A class of miniature probes has been proposed to supplant the fiber-optic probes used heretofore in some Raman and fluorescence spectroscopic systems. A probe according to the proposal would include a capillary tube coated with metal on its inside to make it reflective. A microlens would be hermetically sealed onto one end of the tube. A spectroscopic probe head would contain a single such probe, which would both deliver laser light to a sample and collect Raman or fluorescent light emitted by the sample.

  16. Two-dimensional Raman-terahertz spectroscopy of water

    PubMed Central

    Savolainen, Janne; Ahmed, Saima; Hamm, Peter

    2013-01-01

    Two-dimensional Raman-terahertz (THz) spectroscopy is presented as a multidimensional spectroscopy directly in the far-IR regime. The method is used to explore the dynamics of the collective intermolecular modes of liquid water at ambient temperatures that emerge from the hydrogen-bond networks water forming. Two-dimensional Raman-THz spectroscopy interrogates these modes twice and as such can elucidate couplings and inhomogeneities of the various degrees of freedoms. An echo in the 2D Raman-THz response is indeed identified, indicating that a heterogeneous distribution of hydrogen-bond networks exists, albeit only on a very short 100-fs timescale. This timescale appears to be too short to be compatible with more extended, persistent structures assumed within a two-state model of water. PMID:24297930

  17. Characterization of uranium tetrafluoride (UF4) with Raman spectroscopy

    DOE PAGESBeta

    Villa-Aleman, Eliel; Wellons, Matthew S.

    2016-03-22

    The Raman spectrum of uranium tetrafluoride (UF4) is unambiguously characterized with multiple Raman excitation laser sources for the first time. Across different laser excitation wavelengths, UF4 demonstrates 16 distinct Raman bands within the 50-400 cm-1 region. The observed Raman bands are representative of various F-F vibrational modes. UF4 also shows intense fluorescent bands in the 325 – 750 nm spectral region. Comparison of the UF4 spectrum with the ZrF4 spectrum, its crystalline analog, demonstrates a similar Raman band structure consistent with group theory predictions for expected Raman bands. Additionally, a demonstration of combined scanning electron microscopy (SEM) and in situmore » Raman spectroscopy microanalytical measurements of UF4 particulates shows that despite the inherent weak intensity of Raman bands, identification and characterization are possible for micron-sized particulates with modern instrumentation. The published well characterized UF4 spectrum is extremely relevant to nuclear materials and nuclear safeguard applications.« less

  18. Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods

    PubMed Central

    McCamant, David W.; Kukura, Philipp; Yoon, Sangwoon; Mathies, Richard A.

    2005-01-01

    The laser, detection system, and methods that enable femtosecond broadband stimulated Raman spectroscopy (FSRS) are presented in detail. FSRS is a unique tool for obtaining high time resolution (<100 fs) vibrational spectra with an instrument response limited frequency resolution of <10 cm–1. A titanium:Sapphire-based laser system produces the three different pulses needed for FSRS: (1) A femtosecond visible actinic pump that initiates the photochemistry, (2) a narrow bandwidth picosecond Raman pump that provides the energy reservoir for amplification of the probe, and (3) a femtosecond continuum probe that is amplified at Raman resonances shifted from the Raman pump. The dependence of the stimulated Raman signal on experimental parameters is explored, demonstrating the expected exponential increase in Raman intensity with concentration, pathlength, and Raman pump power. Raman spectra collected under different electronic resonance conditions using highly fluorescent samples highlight the fluorescence rejection capabilities of FSRS. Data are also presented illustrating our ability: (i) To obtain spectra when there is a large transient absorption change by using a shifted excitation difference technique and (ii) to obtain high time resolution vibrational spectra of transient electronic states. PMID:17183413

  19. Characterization of uranium tetrafluoride (UF 4 ) with Raman spectroscopy

    DOE PAGESBeta

    Villa-Aleman, Eliel; Wellons, Matthew S.

    2016-03-22

    The Raman spectrum of uranium tetrafluoride (UF4) is unambiguously characterized with multiple Raman excitation laser sources for the first time. Across different laser excitation wavelengths, UF4 demonstrates 16 distinct Raman bands within the 50-400 cm-1 region. The observed Raman bands are representative of various F-F vibrational modes. UF4 also shows intense fluorescent bands in the 325 – 750 nm spectral region. Comparison of the UF4 spectrum with the ZrF4 spectrum, its crystalline analog, demonstrates a similar Raman band structure consistent with group theory predictions for expected Raman bands. Additionally, a demonstration of combined scanning electron microscopy (SEM) and in situmore » Raman spectroscopy microanalytical measurements of UF4 particulates shows that despite the inherent weak intensity of Raman bands, identification and characterization are possible for micron-sized particulates with modern instrumentation. The published well characterized UF4 spectrum is extremely relevant to nuclear materials and nuclear safeguard applications.« less

  20. Understanding the application of Raman spectroscopy to the detection of traces of life.

    PubMed

    Marshall, Craig P; Edwards, Howell G M; Jehlicka, Jan

    2010-03-01

    Investigating carbonaceous microstructures and material in Earth's oldest sedimentary rocks is an essential part of tracing the origins of life on our planet; furthermore, it is important for developing techniques to search for traces of life on other planets, for example, Mars. NASA and ESA are considering the adoption of miniaturized Raman spectrometers for inclusion in suites of analytical instrumentation to be placed on robotic landers on Mars in the near future to search for fossil or extant biomolecules. Recently, Raman spectroscopy has been used to infer a biological origin of putative carbonaceous microfossils in Early Archean rocks. However, it has been demonstrated that the spectral signature obtained from kerogen (of known biological origin) is similar to spectra obtained from many poorly ordered carbonaceous materials that arise through abiotic processes. Yet there is still confusion in the literature as to whether the Raman spectroscopy of carbonaceous materials can indeed delineate a signature of ancient life. Despite the similar nature in spectra, rigorous structural interrogation between the thermal alteration products of biological and nonbiological organic materials has not been undertaken. Therefore, we propose a new way forward by investigating the second derivative, deconvolution, and chemometrics of the carbon first-order spectra to build a database of structural parameters that may yield distinguishable characteristics between biogenic and abiogenic carbonaceous material. To place Raman spectroscopy as a technique to delineate a biological origin for samples in context, we will discuss what is currently accepted as a spectral signature for life; review Raman spectroscopy of carbonaceous material; and provide a historical overview of Raman spectroscopy applied to Archean carbonaceous materials, interpretations of the origin of the ancient carbonaceous material, and a future way forward for Raman spectroscopy. PMID:20402584

  1. Raman spectroscopy of garnet-group minerals

    USGS Publications Warehouse

    Mingsheng, P.; Mao, Ho-kwang; Dien, L.; Chao, E.C.T.

    1994-01-01

    The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

  2. Surface enhanced Raman spectroscopy of neurotransmitters

    NASA Astrophysics Data System (ADS)

    McGlashen, Michael L.; Davis, Kevin L.; Morris, Michael D.

    1989-10-01

    The surface-enhanced Raman spectra (SERS) of neurotransmitters in biological matrices and synthetic solutions are described. The effects of protein adsorption on cathecholamine SERS intensity are discussed. Techniques for obtaining dopamine SERS spectra in cerebrospinal fluid and rat brain dialysate are demonstrated. Preliminary SERS of histamine and tel-methylhistamine are presented.

  3. Resonance Raman Spectroscopy of Beta-Carotene and Lycopene: A Physical Chemistry Experiment.

    ERIC Educational Resources Information Center

    Hoskins, L. C.

    1984-01-01

    Discusses the theory of resonance Raman (RR) spectroscopy as it applies to beta-carotene and lycopene pigments (found in tomatoes and carrots, respectively). Also discusses an experiment which demonstrates the theoretical principles involved. The experiment has been tested over a three-year period and has received excellent acceptance by physical…

  4. Trace vapour detection at room temperature using Raman spectroscopy.

    PubMed

    Chou, Alison; Radi, Babak; Jaatinen, Esa; Juodkazis, Saulius; Fredericks, Peter M

    2014-04-21

    A miniaturized flow-through system consisting of a gold coated silicon substrate based on enhanced Raman spectroscopy has been used to study the detection of vapour from model explosive compounds. The measurements show that the detectability of the vapour molecules at room temperature depends sensitively on the interaction between the molecule and the substrate. The results highlight the capability of a flow system combined with Raman spectroscopy for detecting low vapour pressure compounds with a limit of detection of 0.2 ppb as demonstrated by the detection of bis(2-ethylhexyl)phthalate, a common polymer additive emitted from a commercial polyvinyl chloride (PVC) tubing at room temperature. PMID:24588003

  5. Review on the Raman spectroscopy of different types of layered materials

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Tan, Qing-Hai; Wu, Jiang-Bin; Shi, Wei; Tan, Ping-Heng

    2016-03-01

    Two-dimensional layered materials, such as graphene and transition metal dichalcogenides (TMDs), have been under intensive investigation. The rapid progress of research on graphene and TMDs is now stimulating the exploration of different types of layered materials (LMs). Raman spectroscopy has shown its great potential in the characterization of layer numbers, interlayer coupling and layer-stacking configurations and will benefit the future explorations of other LMs. Lattice vibrations or Raman spectra of many LMs in bulk have been discussed since the 1960s. However, different results were obtained because of differences or limitations in the Raman instruments at early stages. The developments of modern Raman spectroscopy now allow us to revisit the Raman spectra of these LMs under the same experimental conditions. Moreover, to the best of our knowledge, there were limitations in detailed reviews on the Raman spectra of these different LMs. Here, we provide a review on Raman spectra of various LMs, including semiconductors, topological insulators, insulators, semi-metals and superconductors. We firstly introduce a unified method based on symmetry analysis and polarization measurements to assign the observed Raman modes and characterize the crystal structure of different types of LMs. Then, we revisit and update the positions and assignments of vibration modes by re-measuring the Raman spectra of different types of LMs and by comparing our results to those reported in previous papers. We apply the recent advances on the interlayer vibrations of graphene and TMDs to these various LMs and obtain their shear modulus. The observation of the shear modes of LMs in bulk facilitates an accurate and fast characterization of layer numbers during preparation processes in the future by a robust layer-number dependency on the frequencies of the shear modes. We also summarize the recent advances on the layer-stacking dependence on the intensities of interlayer shear vibrations

  6. Condition Assessment of Kevlar Composite Materials Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

    2007-01-01

    This viewgraph presentation includes the following main concepts. Goal: To evaluate Raman spectroscopy as a potential NDE tool for the detection of stress rupture in Kevlar. Objective: Test a series of strand samples that have been aged under various conditions and evaluate differences and trends in the Raman response. Hypothesis: Reduction in strength associated with stress rupture may manifest from changes in the polymer at a molecular level. If so, than these changes may effect the vibrational characteristics of the material, and consequently the Raman spectra produced from the material. Problem Statement: Kevlar composite over-wrapped pressure vessels (COPVs) on the space shuttles are greater than 25 years old. Stress rupture phenomena is not well understood for COPVs. Other COPVs are planned for hydrogen-fueled vehicles using Carbon composite material. Raman spectroscopy is being explored as an non-destructive evaluation (NDE) technique to predict the onset of stress rupture in Kevlar composite materials. Test aged Kevlar strands to discover trends in the Raman response. Strength reduction in Kevlar polymer will manifest itself on the Raman spectra. Conclusions: Raman spectroscopy has shown relative changes in the intensity and FWHM of the 1613 cm(exp -1) peak. Reduction in relative intensity for creep, fleet leader, and SIM specimens compared to the virgin strands. Increase in FWHM has been observed for the creep and fleet leader specimens compared to the virgin strands. Changes in the Raman spectra may result from redistributing loads within the material due to the disruption of hydrogen bonding between crystallites or defects in the crystallites from aging the Kevlar strands. Peak shifting has not been observed to date. Analysis is ongoing. Stress measurements may provide a tool in the short term.

  7. Kerr-gated picosecond Raman spectroscopy and Raman photon migration of equine bone tissue with 400-nm excitation

    NASA Astrophysics Data System (ADS)

    Morris, Michael D.; Goodship, Allen E.; Draper, Edward R. C.; Matousek, Pavel; Towrie, Michael; Parker, Anthony W.

    2004-07-01

    We show that Raman spectroscopy with visible lasers, even in the deep blue is possible with time-gated Raman spectroscopy. A 4 picosec time gate allows efficient fluorescence rejection, up to 1000X, and provides almost background-free Raman spectra with low incident laser power. The technology enables spectroscopy with better than 10X higher scattering efficiency than is possible with the NIR (785 nm and 830 nm) lasers that are conventionally used. Raman photon migration is shown to allow depth penetration. We show for the first time that Kerr-gated Raman spectra of bone tissue with blue laser excitation enables both fluorescence rejection and depth penetration.

  8. Simulated Raman correlation spectroscopy for quantifying nucleic acid-silver composites

    NASA Astrophysics Data System (ADS)

    Freeman, Lindsay M.; Smolyaninov, Alexei; Pang, Lin; Fainman, Yeshaiahu

    2016-03-01

    Plasmonic devices are of great interest due to their ability to confine light to the nanoscale level and dramatically increase the intensity of the electromagnetic field, functioning as high performance platforms for Raman signal enhancement. While Raman spectroscopy has been proposed as a tool to identify the preferential binding sites and adsorption configurations of molecules to nanoparticles, the results have been limited by the assumption that a single binding site is responsible for molecular adsorption. Here, we develop the simulated Raman correlation spectroscopy (SRCS) process to determine which binding sites of a molecule preferentially bind to a plasmonic material and in what capacity. We apply the method to the case of nucleic acids binding to silver, discovering that multiple atoms are responsible for adsorption kinetics. This method can be applied to future systems, such as to study the molecular orientation of adsorbates to films or protein conformation upon adsorption.

  9. Simulated Raman correlation spectroscopy for quantifying nucleic acid-silver composites

    PubMed Central

    Freeman, Lindsay M.; Smolyaninov, Alexei; Pang, Lin; Fainman, Yeshaiahu

    2016-01-01

    Plasmonic devices are of great interest due to their ability to confine light to the nanoscale level and dramatically increase the intensity of the electromagnetic field, functioning as high performance platforms for Raman signal enhancement. While Raman spectroscopy has been proposed as a tool to identify the preferential binding sites and adsorption configurations of molecules to nanoparticles, the results have been limited by the assumption that a single binding site is responsible for molecular adsorption. Here, we develop the simulated Raman correlation spectroscopy (SRCS) process to determine which binding sites of a molecule preferentially bind to a plasmonic material and in what capacity. We apply the method to the case of nucleic acids binding to silver, discovering that multiple atoms are responsible for adsorption kinetics. This method can be applied to future systems, such as to study the molecular orientation of adsorbates to films or protein conformation upon adsorption. PMID:27010074

  10. Raman and optical spectroscopy of eumelanin films

    NASA Astrophysics Data System (ADS)

    Capozzi, V.; Perna, G.; Gallone, A.; Biagi, P. F.; Carmone, P.; Fratello, A.; Guida, G.; Zanna, P.; Cicero, R.

    2005-06-01

    Melanin obtained from the liver of Rana esculenta L., was isolated from melanosomes and deposited as thin film on quartz substrate, in order to perform Raman, absorption and photoluminescence measurements at room temperature. The Raman spectrum was analysed by considering the contribution of the vibrational modes from different functional groups of the melanin structure. The absorption and photoluminescence measurements support the model that melanin consists of nano-aggregates of oligomeric structures rather than extended heteropolymer. An optical gap value of about 0.6 eV was estimated by considering the Tauc model. The largest size group of clusters mainly contribute to determine the optical gap value, whereas the PL emission is due to groups of clusters which are selectively pumped.

  11. Raman spectroscopy for bacterial identification and characterization

    NASA Astrophysics Data System (ADS)

    Bernatová, Silvie; Samek, Ota; Pilát, Zdeněk.; Šerý, Mojmír.; Ježek, Jan; Krzyžánek, Vladislav; Zemánek, Pavel; Ružička, Filip

    2012-01-01

    The main goal of our investigation is to use Raman tweezers technique so that the responce of Raman scattering on microorganisms suspended in liquid media (bacteria, algae and yeast cells in microfluidic chips) can be used to identify different species. The investigations presented here include identification of different bacteria strains (biofilm-positive and biofilm-negative) and yeast cells by using principal component analysis (PCA). The main driving force behind our investigation was a common problem in the clinical microbiology laboratory - how to distinguish between contaminant and invasive isolates. Invasive bacterial/yeast isolates can be assumed to form a biofilm, while isolates which do not form a biofilm can be treated as contaminant. Thus, the latter do not represent an important virulence factor.

  12. Novel developments in laser diode Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Claps, Ricardo Javier

    2000-11-01

    This thesis presents the last developments of a laser diode Raman spectrometer for gases, gas flows and vapors, at medium-low pressures. Results are shown for atmospheric gases under STP conditions, and also gas flows from nozzles in subsonic-sonic regimes. The system is unique in that it uses a high power laser diode passively locked by an external grating cavity in Littman/Metcalf configuration, with side-band modes suppressed by 1:10-5, and a reduced bandwidth of <500MHz. The use of Rb vapor cells as notch filters with unprecedented narrow bandwidth (<7 cm-1), allow to collect Stokes and a-Stokes rotational Raman spectra simultaneously. The spectrometer is used to perform studies of thermodynamic equilibrium of gas flows; further studies of samples seeded in the flow (alkali- halides) are discussed, together with potential applications for environmental and industrial monitoring.

  13. Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy.

    PubMed

    Galván, Ismael; Jorge, Alberto; Solano, Francisco; Wakamatsu, Kazumasa

    2013-06-01

    We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm(-1) wavenumber region about 500, 1150, 1490 and 2000 cm(-1), which we assigned to the out-of-plane deformation and the stretching vibration of the phenyl rings, to the stretching vibration of C-N bonds or the stretching and wagging vibration of CH2, and to overtone or combination bands. Interestingly, we also show that the Raman spectrum of synthetic trichochrome F, a pigment that may be produced along with pheomelanin during pheomelanogenesis, is different from that of pheomelanin and similar to the spectrum of eumelanin. We could detect Raman signal of both eumelanin and pheomelanin in feathers and hairs where both pigments simultaneously occur without the need of isolating the pigment. This indicates that Raman spectroscopy represents a non-invasive method to detect pheomelanin and distinguish it from other pigments. This may be especially relevant to detect pheomelanin in animal skin including humans, where it has been associated with animal appearance and classification, human phototypes, prevention of skin diseases and cancer risk. PMID:23563634

  14. [Study on the treatment turquoise using Raman spectroscopy].

    PubMed

    Chen, Quan-li; Yuan, Xin-qiang; Chen, Jing-zhong; Qi, Li-jian

    2010-07-01

    Due to a variety of the enhancement and treatment turquoises discovered in gem markets, the identification of turquoise is becoming more and more difficult. By using laser Raman spectroscopy analysis, the characteristics of Raman spectra of the pressed and filled turquoises were studied. The results show that laser Raman spectroscopy is an effective technique to identify the enhancement and treatment turquoises and the natural ones, moreover, it's a non-destructive testing method. The Raman spectra of the enhancement and treatment turquoises are resulted mainly from the vibrational mode and frequency of water, hydroxyl units, PO4 tetrahedron and CH2 units. Besides, they have the characteristic Raman spectra peaks at 2,937, 2,883 and 1,451 cm(-1) which are attributed to the stretching vibration and the bending vibration of CH2, respectively. These characteristic Raman vibration bands, it will help to distinguish the natural turquoises and the treatment ones. The study provides a new train of thought on the rapid, accurate, and non-destructive identification of turquoise. PMID:20827971

  15. Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Galván, Ismael; Jorge, Alberto; Solano, Francisco; Wakamatsu, Kazumasa

    2013-06-01

    We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm-1 wavenumber region about 500, 1150, 1490 and 2000 cm-1, which we assigned to the out-of-plane deformation and the stretching vibration of the phenyl rings, to the stretching vibration of C-N bonds or the stretching and wagging vibration of CH2, and to overtone or combination bands. Interestingly, we also show that the Raman spectrum of synthetic trichochrome F, a pigment that may be produced along with pheomelanin during pheomelanogenesis, is different from that of pheomelanin and similar to the spectrum of eumelanin. We could detect Raman signal of both eumelanin and pheomelanin in feathers and hairs where both pigments simultaneously occur without the need of isolating the pigment. This indicates that Raman spectroscopy represents a non-invasive method to detect pheomelanin and distinguish it from other pigments. This may be especially relevant to detect pheomelanin in animal skin including humans, where it has been associated with animal appearance and classification, human phototypes, prevention of skin diseases and cancer risk.

  16. Raman spectroscopy and oral exfoliative cytology

    NASA Astrophysics Data System (ADS)

    Sahu, Aditi; Shah, Nupur; Mahimkar, Manoj; Garud, Mandavi; Pagare, Sandeep; Nair, Sudhir; Krishna, C. Murali

    2014-03-01

    Early detection of oral cancers can substantially improve disease-free survival rates. Ex vivo and in vivo Raman spectroscopic (RS) studies on oral cancer have demonstrated the applicability of RS in identifying not only malignant and premalignant conditions but also cancer-field-effects: the earliest events in oral carcinogenesis. RS has also been explored for cervical exfoliated cells analysis. Exfoliated cells are associated with several advantages like non-invasive sampling, higher patient compliance, transportation and analysis at a central facility: obviating need for on-site instrumentation. Thus, oral exfoliative cytology coupled with RS may serve as a useful adjunct for oral cancer screening. In this study, exfoliated cells from healthy controls with and without tobacco habits, premalignant lesions (leukoplakia and tobacco-pouch-keratosis) and their contralateral mucosa were collected using a Cytobrush. Cells were harvested by vortexing and centrifugation at 6000 rpm. The cellular yield was ascertained using Neubauer's chamber. Cell pellets were placed on a CaF2 window and Raman spectra were acquired using a Raman microprobe (40X objective) coupled HE-785 Raman spectrometer. Approximately 7 spectra were recorded from each pellet, following which pellet was smeared onto a glass slide, fixed in 95% ethanol and subjected to Pap staining for cytological diagnosis (gold standard). Preliminary PC-LDA followed by leave-one-out cross validation indicate delineation of cells from healthy and all pathological conditions. A tendency of classification was also seen between cells from contralateral, healthy tobacco and site of premalignant lesions. These results will be validated by cytological findings, which will serve as the basis for building standard models of each condition.

  17. X-ray resonant Raman spectroscopy

    SciTech Connect

    Cowan, P.L.; LeBrun, T.; Deslattes, R.D.

    1995-08-01

    X-ray resonant Raman scattering presents great promise as a high-resolution spectroscopic probe of the electronic structure of matter. Unlike other methods, the technique avoids the loss of energy resolution resulting from the lifetime broadening of short-lived core-excited states. In addition, measurements of polarization and angular anisotropies yield information on the symmetries of electronic states of atoms and molecules. We studied the L{sub 3} edge of xenon, where the lifetime broadening is a major feature of the spectra recorded previously. X-ray fluorescence spectra were taken of both the L{alpha}{sub l,2} and L{beta}{sub 2,15} peaks over a range of energies from 10 eV below the edge to 40 eV above. These spectra show the evolution of resonant Raman scattering into characteristic fluorescence as the photon energy is scanned across the edge, and confirm several features of these spectra such as asymmetries in resonant peak shapes due to the onset of the ionization continuum. These results constitute the most comprehensive study of X-ray resonant Raman scattering to date, and were submitted for publication. Studies of other cases are under way, and new instruments that would match the unique characteristics of the APS - and thus render a new range of experiments possible - are under consideration.

  18. Detection of nasopharyngeal cancer using confocal Raman spectroscopy and genetic algorithm technique

    NASA Astrophysics Data System (ADS)

    Li, Shao-Xin; Chen, Qiu-Yan; Zhang, Yan-Jiao; Liu, Zhi-Ming; Xiong, Hong-Lian; Guo, Zhou-Yi; Mai, Hai-Qiang; Liu, Song-Hao

    2012-12-01

    Raman spectroscopy (RS) and a genetic algorithm (GA) were applied to distinguish nasopharyngeal cancer (NPC) from normal nasopharyngeal tissue. A total of 225 Raman spectra are acquired from 120 tissue sites of 63 nasopharyngeal patients, 56 Raman spectra from normal tissue and 169 Raman spectra from NPC tissue. The GA integrated with linear discriminant analysis (LDA) is developed to differentiate NPC and normal tissue according to spectral variables in the selected regions of 792-805, 867-880, 996-1009, 1086-1099, 1288-1304, 1663-1670, and 1742-1752 cm-1 related to proteins, nucleic acids and lipids of tissue. The GA-LDA algorithms with the leave-one-out cross-validation method provide a sensitivity of 69.2% and specificity of 100%. The results are better than that of principal component analysis which is applied to the same Raman dataset of nasopharyngeal tissue with a sensitivity of 63.3% and specificity of 94.6%. This demonstrates that Raman spectroscopy associated with GA-LDA diagnostic algorithm has enormous potential to detect and diagnose nasopharyngeal cancer.

  19. 1064 nm FT-Raman spectroscopy for investigations of plant cell walls and other biomass materials

    PubMed Central

    Agarwal, Umesh P.

    2014-01-01

    Raman spectroscopy with its various special techniques and methods has been applied to study plant biomass for about 30 years. Such investigations have been performed at both macro- and micro-levels. However, with the availability of the Near Infrared (NIR) (1064 nm) Fourier Transform (FT)-Raman instruments where, in most materials, successful fluorescence suppression can be achieved, the utility of the Raman investigations has increased significantly. Moreover, the development of several new capabilities such as estimation of cellulose-crystallinity, ability to analyze changes in cellulose conformation at the local and molecular level, and examination of water-cellulose interactions have made this technique essential for research in the field of plant science. The FT-Raman method has also been applied to research studies in the arenas of biofuels and nanocelluloses. Moreover, the ability to investigate plant lignins has been further refined with the availability of near-IR Raman. In this paper, we present 1064-nm FT-Raman spectroscopy methodology to investigate various compositional and structural properties of plant material. It is hoped that the described studies will motivate the research community in the plant biomass field to adapt this technique to investigate their specific research needs. PMID:25295049

  20. Remote sensing of subsurface water temperature by laser Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Leonard, D. A.; Caputo, B.; Guagliardo, J. L.; Hoge, F. E.

    1980-01-01

    This paper describes experimental remote sensing of subsurface water temperature using the Raman spectroscopic technique. By the use of a pulsed laser and range gating detection techniques, Raman scattering is analyzed as a function of depth in a radar-like echo mode, and thus subsurface profiles of temperature and transmission are obtained. Experiments are described in which Raman data using polarization spectroscopy has been obtained from a ship as a function of depth in ocean water near Grand Bahama Island. A spectral temperature accuracy of + or - 1 C has been obtained from this data in the first two optical attenuation lengths. Raman data obtained from ocean water using the NASA airborne oceanographic lidar is also presented.

  1. Fluorescence suppression using micro-scale spatially offset Raman spectroscopy.

    PubMed

    Conti, Claudia; Botteon, Alessandra; Colombo, Chiara; Realini, Marco; Matousek, Pavel

    2016-09-21

    We present a new concept of fluorescence suppression in Raman microscopy based on micro-spatially offset Raman spectroscopy which is applicable to thin stratified turbid (diffusely scattering) matrices permitting the retrieval of the Raman signals of sublayers below intensely fluorescing turbid over-layers. The method is demonstrated to yield good quality Raman spectra with dramatically suppressed fluorescence backgrounds enabling the retrieval of Raman sublayer signals even in situations where conventional Raman microscopy spectra are fully overwhelmed by intense fluorescence. The concept performance was studied theoretically using Monte Carlo simulations indicating the potential of up to an order or two of magnitude suppression of overlayer fluorescence backgrounds relative to the Raman sublayer signals. The technique applicability was conceptually demonstrated on layered samples involving paints, polymers and stones yielding fluorescence suppression factors between 12 to above 430. The technique has potential applications in a number of analytical areas including cultural heritage, archaeology, polymers, food, pharmaceutical, biological, biomedical, forensics and catalytic sciences and quality control in manufacture. PMID:27338230

  2. [Measurement of nasopharyngeal carcinoma tissue ex vivo by Raman spectroscopy].

    PubMed

    Huang, Wei; Pan, Jian-ji; Chen, Rong; Li, Yong-zeng; Feng, Shang-yuan; Xie, Shu-sen; Zeng, Hai-shan

    2009-05-01

    Raman spectroscopy has shown its potential and advantages in detecting molecular changes associated with tissue pathology, which makes it possible to diagnose with optical methods non-invasively and real-time. A compact and rapid near-infrared (NIR)Raman system was developed using 785 nm diode laser, volume phase technology (VPT)holographic grating system and NIR intensified charge-coupled device (CCD)with a specially designed Raman fibre probe which can effectively reduce the interference of fluorescence and Rayleigh scattering, maximize the ability of Raman collection as well as correct the image aberration of a planar grating diffraction. Adopting this method, signal-to-noise ratio has been greatly improved and human tissue signals can be acquired in a short time. Raman signals from fat and musculature of fresh pork were measured and referenced for further optimization, then Raman spectra of nasopharyngeal carcinoma in vitro and the effect of storage time on them were measured in 1-5 s and discussed. The sensitivities and performance of the system will be further enhanced and more Raman data will be acquired and compared between normal and cancerous nasopharyngeal tissue, expecting to discover the statistical characteristics, which will benefit the diagnosis and treatment of early nasopharyngeal carcinoma or other tumors. PMID:19650477

  3. Raman-spectroscopy-based biosensing for applications in ophthalmology

    NASA Astrophysics Data System (ADS)

    Rusciano, Giulia; Capriglione, Paola; Pesce, Giuseppe; Zito, Gianluigi; Del Prete, Antonio; Cennamo, Giovanni; Sasso, Antonio

    2013-05-01

    Cell-based biosensors rely on the detection and identification of single cells as well as monitoring of changes induced by interaction with drugs and/or toxic agents. Raman spectroscopy is a powerful tool to reach this goal, being non-destructive analytical technique, allowing also measurements of samples in aqueous environment. In addition, micro-Raman measurements do not require preliminary sample preparation (as in fluorescence spectroscopy), show a finger-print spectral response, allow a spatial resolution below typical cell sizes, and are relatively fast (few s or even less). All these properties make micro-Raman technique particularly promising for high-throughput on-line analysis integrated in lab-on-a-chip devices. Herein, we demonstrate some applications of Raman analysis in ophthalmology. In particular, we demonstrate that Raman analysis can provide useful information for the therapeutic treatment of keratitis caused by Acanthamoeba Castellanii (A.), an opportunistic protozoan that is widely distributed in the environment and is known to produce blinding keratitis and fatal encephalitis. In particular, by combining Raman analysis with Principal Component Analysis (PCA), we have demonstrated that is possible to distinguish between live and dead cells, enabling, therefore to establish the effectiveness of therapeutic strategies to vanquish the protozoa. As final step, we have analyzed the presence of biochemical differences in the conjunctival epithelial tissues of patients affected by keratitis with respect to healthy people. As a matter of facts, it is possible to speculate some biochemical alterations of the epithelial tissues, rendering more favorable the binding of the protozoan. The epithelial cells were obtained by impression cytology from eyes of both healthy and keratitis-affected individuals. All the samples were analyzed by Raman spectroscopy within a few hours from cells removal from eyes. The results of this analysis are discussed.

  4. Cone penetrometer fiber optic raman spectroscopy probe assembly

    DOEpatents

    Kyle, Kevin R.; Brown, Steven B.

    2000-01-01

    A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  5. Cone penetrometer fiber optic Raman spectroscopy probe assembly

    SciTech Connect

    Kyle, K.R.; Brown, S.B.

    2000-01-25

    A chemically and mechanically robust optical Raman spectroscopy probe assembly is described that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics to the light source and the detection system at the surface. A built-in broadband light source provides a strobe method for direct measurement of sample optical density. A mechanically stable sapphire window is sealed directly into the side-wall of the housing using a metallic, chemically resistant, hermetic seal design. This window permits transmission of the interrogation light beam and the resultant signal. The spectroscopy probe assembly is capable of accepting Raman, Laser induced Fluorescence, reflectance, and other optical probes with collimated output for CPT deployment.

  6. Imaging EGFR distribution using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lucas, L.; Chen, X. K.; Smith, A.; Korbelik, M.; Zeng, H.; Lee, P. W. K.; Hewitt, K. C.

    2009-02-01

    The purpose of this study is to explore the feasibility of using Surface Enhanced Raman Spectroscopy (SERS) to image the distribution of Epidermal Growth Factor Receptor (EGFR) in cells. To accomplish this task, 30 nm gold nanoparticles (AuNPs) tagged with antibodies to EGFR (1012 per ml) are incubated with cells (106 per ml) of the A431 human epidermoid carcinoma cell line and normal human bronchial epithelial (NHBE) cells. Using the 632.8 nm excitation line of a He-Ne laser, Raman spectroscopy measurements are performed using a point mapping scheme. SERS signals are observed with an overall enhancement of 4-7 orders of magnitude. Raman intensity maps of the 1480 and 1583 cm-1 peaks correlate well with the expected distribution of AuNPs and EGFR. Normal cells show little to no enhancement. The results therefore present a simple yet effective means to image EGFR over-expression.

  7. Raman spectroscopy for in-situ monitoring of electrode processes

    SciTech Connect

    Varma, R; Cook, G M; Yao, N P

    1982-04-01

    The theoretical and experimental applications of Raman spectroscopic techniques to the study of battery electrode processes are described. In particular, the potential of Raman spectroscopy as an in-situ analytical tool for the characterization of the structure and composition of electrode surface layers at electrode-electrolyte interfaces during electrolysis is examined. It is anticipated that this understanding of the battery electrode processes will be helpful in designing battery active material with improved performance. The applications of Raman spectroscopy to the in-situ study of electrode processes has been demonstrated in a few selected areas, including: (1) the anodic corrosion of lead in sulfuric acid and (2) the anodization and sulfation of tetrabasicleadsulfate in sulfuric acid. Preliminary results on the anodization of iron and on the electrochemical behavior of nickel positive-electrode active material in potassium hydroxide electrolytes are presented in the Appendix.

  8. Principle, system, and applications of tip-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, MingQian; Wang, Rui; Wu, XiaoBin; Wang, Jia

    2012-08-01

    Raman spectroscopy is a powerful technique in chemical information characterization. However, this spectral method is subject to two obstacles in nano-material detection. One is diffraction limited spatial resolution, and the other is its inherent small Raman cross section and weak signaling. To resolve these problems, a new approach has been developed, denoted as tip-enhanced Raman spectroscopy (TERS). TERS is capable of high-resolution and high-sensitivity detection and demonstrated to be a promising spectroscopic and micro-topographic method to characterize nano-materials and nanostructures. In this paper, the principle and experimental system of TERS are discussed. The latest application of TERS in molecule detection, biological specimen identification, nanao-material characterization, and semi-conductor material determination with some specific experimental examples are presented.

  9. FT-Raman spectroscopy of lichen species from the Antarctic

    NASA Astrophysics Data System (ADS)

    Holder, J. M.; Edwards, H. G. M.; Wynn-Williams, D. D.

    1998-06-01

    In this investigation, FT-Raman spectroscopy has been utilized to characterize pigments and chemicals produced by Antarctic lichens, which have been exposed to increasing levels of UV-B radiation and other environmental conditions. The presence of calcium oxalate in some lichen species has also been confirmed spectroscopically.

  10. Analysis of scorpion venom composition by Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Martínez-Zérega, Brenda E.; González-Solís, José L.

    2015-01-01

    In this work we study the venom of two Centruroides scorpion species using Raman spectroscopy. The spectra analysis allows to determine the venoms chemical composition and to establish the main differences and similarities among the species. It is also shown that the use of Principal Component Analysis may help to tell apart between the scorpion species.

  11. Stress Analysis of SiC MEMS Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ness, Stanley J.; Marciniak, M. A.; Lott, J. A.; Starman, L. A.; Busbee, J. D.; Melzak, J. M.

    2003-03-01

    During the fabrication of Micro-Electro-Mechanical Systems (MEMS), residual stress is often induced in the thin films that are deposited to create these systems. These stresses can cause the device to fail due to buckling, curling, or fracture. Industry is looking for ways to characterize the stress during the deposition of thin films in order to reduce or eliminate device failure. Micro-Raman spectroscopy has been successfully used to characterize poly-Si MEMS devices made with the MUMPS® process. Raman spectroscopy was selected because it is nondestructive, fast and has the potential for in situ stress monitoring. This research attempts to use Raman spectroscopy to analyze the stress in SiC MEMS made with the MUSiC® process. Raman spectroscopy is performed on 1-2-micron-thick SiC thin films deposited on silicon, silicon nitride, and silicon oxide substrates. The most common poly-type of SiC found in thin film MEMS made with the MUSiC® process is 3C-SiC. Research also includes baseline spectra of 6H, 4H, and 15R poly-types of bulk SiC.

  12. THz-Raman: accessing molecular structure with Raman spectroscopy for enhanced chemical identification, analysis, and monitoring

    NASA Astrophysics Data System (ADS)

    Heyler, Randy A.; Carriere, James T. A.; Havermeyer, Frank

    2013-05-01

    Structural analysis via spectroscopic measurement of rotational and vibrational modes is of increasing interest for many applications, since these spectra can reveal unique and important structural and behavioral information about a wide range of materials. However these modes correspond to very low frequency (~5cm-1 - 200cm-1, or 150 GHz-6 THz) emissions, which have been traditionally difficult and/or expensive to access through conventional Raman and Terahertz spectroscopy techniques. We report on a new, inexpensive, and highly efficient approach to gathering ultra-low-frequency Stokes and anti-Stokes Raman spectra (referred to as "THz-Raman") on a broad range of materials, opening potential new applications and analytical tools for chemical and trace detection, identification, and forensics analysis. Results are presented on explosives, pharmaceuticals, and common elements that show strong THz-Raman spectra, leading to clear discrimination of polymorphs, and improved sensitivity and reliability for chemical identification.

  13. Simulating two-dimensional infrared-Raman and Raman spectroscopies for intermolecular and intramolecular modes of liquid water.

    PubMed

    Ito, Hironobu; Tanimura, Yoshitaka

    2016-02-21

    Full classical molecular dynamics (MD) simulations of two-dimensional (2D) infrared-Raman and 2D Raman spectroscopies of liquid water were carried out to elucidate a mode-mode coupling mechanism using a polarizable water model for intermolecular and intramolecular vibrational spectroscopy (POLI2VS). This model is capable of describing both infrared and Raman spectra. Second-order response functions, which consist of one molecular polarizability and two molecular dipole moments for 2D IR-Raman and three molecular polarizabilities for 2D Raman spectroscopies, were calculated using an equilibrium-non-equilibrium hybrid MD approach. The obtained signals were analyzed using a multi-mode Brownian oscillator (BO) model with nonlinear system-bath interactions representing the intramolecular OH stretching, intramolecular HOH bending, hydrogen bonded (HB)-intermolecular librational motion and HB-intermolecular vibrational (translational) motion of liquid water. This model was applied through use of hierarchal Fokker-Planck equations. The qualitative features of the peak profiles in the 2D spectra obtained from the MD simulations are accurately reproduced with the BO model. This indicates that this model captures the essential features of the intermolecular and intramolecular motion. We elucidate the mechanisms governing the 2D signal profiles involving anharmonic mode-mode coupling, the nonlinearities of the polarizability and dipole moment, and the vibrational dephasing processes of liquid water even in the case that the 2D spectral peaks obtained from the MD simulation overlap or are unclear. The mode coupling peaks caused by electrical anharmonic coupling (EAHC) and mechanical anharmonic coupling (MAHC) are observed in all of the 2D spectra. We find that the strength of the MAHC between the OH-stretching and HB-intermolecular vibrational modes is comparable to that between the OH-stretching and HOH bending modes. Moreover, we find that this OH-stretching and HB

  14. Remote detection of explosives using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Fulton, Jack

    2011-05-01

    Stand-off detection of potentially hazardous small molecules at distances that allow the user to be safe has many applications, including explosives and chemical threats. The Naval Surface Warfare Center, Crane Division, with EYZtek, Inc. of Ohio, developed a prototype stand-off, eye-safe Raman spectrometer. With a stand-off distance greater than twenty meters and scanning optics, this system has the potential of addressing particularly difficult challenges in small molecule detection. An overview of the system design and desired application space is presented.

  15. A line-scan hyperspectral Raman system for spatially offset Raman spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Conventional methods of spatially offset Raman spectroscopy (SORS) typically use single-fiber optical measurement probes to slowly and incrementally collect a series of spatially offset point measurements moving away from the laser excitation point on the sample surface, or arrays of multiple fiber ...

  16. Spectroscopic fingerprint of tea varieties by surface enhanced Raman spectroscopy.

    PubMed

    Buyukgoz, Guluzar Gorkem; Soforoglu, Mehmet; Basaran Akgul, Nese; Boyaci, Ismail Hakki

    2016-03-01

    The fingerprinting method is generally performed to determine specific molecules or the behavior of specific molecular bonds in the desired sample content. A novel, robust and simple method based on surface enhanced Raman spectroscopy (SERS) was developed to obtain the full spectrum of tea varieties for detection of the purity of the samples based on the type of processing and cultivation. For this purpose, the fingerprint of seven different varieties of tea samples (herbal tea (rose hip, chamomile, linden, green and sage tea), black tea and earl grey tea) combined with silver colloids was obtained by SERS in the range of 200-2000 cm(-1) with an analysis time of 20 s. Each of the thirty-nine tea samples tested showed its own specific SERS spectra. Principal Component Analysis (PCA) was also applied to separate of each tea variety and different models developed for tea samples including three different models for the herbal teas and two different models for black and earl grey tea samples. Herbal tea samples were separated using mean centering, smoothing and median centering pre-processing steps while baselining and derivatisation pre-processing steps were applied to SERS data of black and earl grey tea. The novel spectroscopic fingerprinting technique combined with PCA is an accurate, rapid and simple methodology for the assessment of tea types based on the type of processing and cultivation differences. This method is proposed as an alternative tool in order to determine the characteristics of tea varieties. PMID:27570296

  17. Application of Raman Spectroscopy and Infrared Spectroscopy in the Identification of Breast Cancer.

    PubMed

    Depciuch, Joanna; Kaznowska, Ewa; Zawlik, Izabela; Wojnarowska, Renata; Cholewa, Marian; Heraud, Philip; Cebulski, Józef

    2016-02-01

    Raman spectroscopy and infrared (IR) spectroscopy are both techniques that allow for the investigation of vibrating chemical particles. These techniques provide information not only about chemical particles through the identification of functional groups and spectral analysis of so-called "fingerprints", these methods allow for the qualitative and quantitative analyses of chemical substances in the sample. Both of these spectral techniques are frequently being used in biology and medicine in diagnosing illnesses and monitoring methods of therapy. The type of breast cancer found in woman is often a malignant tumor, causing 1.38 million new cases of breast cancer and 458 000 deaths in the world in 2013. The most important risk factors for breast cancer development are: sex, age, family history, specific benign breast conditions in the breast, ionizing radiation, and lifestyle. The main purpose of breast cancer screening tests is to establish early diagnostics and to apply proper treatment. Diagnoses of breast cancer are based on: (1) physical techniques (e.g., ultrasonography, mammography, elastography, magnetic resonance, positron emission tomography [PET]); (2) histopathological techniques; (3) biological techniques; and (4) optical techniques (e.g., photo acoustic imaging, fluorescence tomography). However, none of these techniques provides unique or especially revealing answers. The aim of our study is comparative spectroscopic measurements on patients with the following: normal non-cancerous breast tissue; breast cancer tissues before chemotherapy; breast cancer tissues after chemotherapy; and normal breast tissues received around the cancerous breast region. Spectra collected from breast cancer patients shows changes in amounts of carotenoids and fats. We also observed changes in carbohydrate and protein levels (e.g., lack of amino acids, changes in the concentration of amino acids, structural changes) in comparison with normal breast tissues. This fact

  18. Mapping residual stress fields from Vickers hardness indents using Raman microprobe spectroscopy

    SciTech Connect

    Sparks, R.G.; Enloe, W.S.; Paesler, M.A.

    1988-12-01

    Micro-Raman spectroscopy is used to map the residual stress fields in the vicinity of Vickers hardness indents. Both 514.5 and 488.0 nm, light is used to excite the effect and the resulting shifted and broadened Raman peaks are analyzed using computer deconvolution. Half-wave plates are used to vary the orientation of the incident later light`s polarization state with respect to crystal orientation. The Raman scattered light is then analyzed for polarization dependences which are indicative of the various components of the Raman scattering tensor. Such studies can yield valuable information about the orientation of stress components in a well known stress field. The results can then be applied to the determination of stress components in machined semiconductor materials.

  19. Coherent Raman dual-comb spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

    Ideguchi, Takuro; Holzner, Simon; Bernhardt, Birgitta; Guelachvili, Guy; Hänsch, Theodor W.; Picqué, Nathalie

    2014-11-01

    The invention of the optical frequency comb technique has revolutionized the field of precision spectroscopy, providing a way to measure the absolute frequency of any optical transition. Since, frequency combs have become common equipment for frequency metrology. In the last decade, novel applications for the optical frequency comb have been demonstrated beyond its original purpose. Broadband molecular spectroscopy is one of those. One such technique of molecular spectroscopy with frequency combs, dual-comb Fourier transform spectroscopy provides short measurement times with resolution and accuracy. Two laser frequency combs with slightly different repetition frequencies generate pairs of pulses with a linearly-scanned delay between pulses in a pair. The system without moving parts mimics a fast scanning Fourier transform interferometer. The measurement speed may be several orders of magnitude faster than that of a Michelson-based Fourier transform spectrometer, which opens up new opportunities for broadband molecular spectroscopy. Recently, dual-comb spectroscopy has been extended to nonlinear phenomena. A broadband Raman spectrum of molecular fingerprints may be measured within a few tens of microseconds with coherent Raman dual-comb spectroscopy. Raster scanning the sample leads to hyperspectral images. This rapid and broadband label-free vibrational spectroscopy and imaging technique might provide new diagnostic methods in a variety of scientific and industrial fields.

  20. Micro spatial analysis of seashell surface using laser-induced breakdown spectroscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lu, Yuan; Li, Yuandong; Li, Ying; Wang, Yangfan; Wang, Shi; Bao, Zhenmin; Zheng, Ronger

    2015-08-01

    The seashell has been studied as a proxy for the marine researches since it is the biomineralization product recording the growth development and the ocean ecosystem evolution. In this work a hybrid of Laser Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy was introduced to the composition analysis of seashell (scallop, bivalve, Zhikong). Without any sample treatment, the compositional distribution of the shell was obtained using LIBS for the element detection and Raman for the molecule recognition respectively. The elements Ca, K, Li, Mg, Mn and Sr were recognized by LIBS; the molecule carotene and carbonate were identified with Raman. It was found that the LIBS detection result was more related to the shell growth than the detection result of Raman. The obtained result suggested the shell growth might be developing in both horizontal and vertical directions. It was indicated that the LIBS-Raman combination could be an alternative way for the shell researches.

  1. Remote detection of trace effluents using Resonance Raman spectroscopy: Field results and evaluation

    SciTech Connect

    Sedlacek, A.J.; Chen, C.L.

    1995-10-01

    Resonance Raman spectroscopy (RRS) possesses many characteristics that are important for detecting, identifying and monitoring chemical effluents. Raman scattering is a coherent, inelastic, two-photon scattering process where an exciting photon of energy h{nu} promotes a molecule to a virtual level and the subsequently emitted photon is shifted in frequency in accordance with the rotational-vibrational structure of the irradiated species, thereby providing a unique fingerprint of the molecule. Under resonance enhancement, the Raman scattering cross-sections have been observed to increase up to 6 orders of magnitude above the normal scattering cross-sections, thereby providing the practical basis for a remote chemical sensor. Some of the other advantages that a Raman sensor possesses are: (1) very high selectivity (chemical specific fingerprints), (2) independence of the spectral fingerprint on the excitation wavelength (ability to monitor in the solar blind region), (3) chemical mixture fingerprints are the sum of its individual components (no spectral cross-talk), (4) near independence of the Raman fingerprint to its physical state (very similar spectra for gas, liquid, solid or solutions), (5) no absolute calibration is necessary because all Raman signals observed from a given species can be compared with the Raman signal for N{sub 2}, whose concentration is known very accurately, and (6) insensitivity of the Raman signature to environmental conditions (no quenching, or interference from water vapor). In this presentation, the technology of resonance Raman spectroscopy as applied to the detection of narcotics production activities will be presented along with some recent experimental results.

  2. Femtosecond stimulated Raman spectroscopy by six-wave mixing

    NASA Astrophysics Data System (ADS)

    Molesky, Brian P.; Guo, Zhenkun; Moran, Andrew M.

    2015-06-01

    Femtosecond Stimulated Raman Spectroscopy (FSRS) is motivated by the knowledge of the molecular geometry changes that accompany sub-picosecond chemical reactions. The detection of vibrational resonances throughout the entire fingerprint region of the spectrum with sub-100-fs delay precision is fairly straightforward to accomplish with the FSRS technique. Despite its utility, FSRS must contend with substantial technical challenges that stem from a large background of residual laser light and lower-order nonlinearities when all laser pulses are electronically resonant with the equilibrium system. In this work, a geometry based on five incident laser beams is used to eliminate much of this undesired background in experiments conducted on metmyoglobin. Compared to a three-beam FSRS geometry with all electronically resonant laser pulses, the five-beam approach described here offers major improvements in the data acquisition rate, sensitivity, and background suppression. The susceptibility of the five-beam geometry to experimental artifacts is investigated using control experiments and model calculations. Of particular concern are undesired cascades of third-order nonlinearities, which are known to challenge FSRS measurements carried out on electronically off-resonant systems. It is generally understood that "forbidden" steps in the desired nonlinear optical processes are the origin of the problems encountered under off-resonant conditions. In contrast, the present experiments are carried out under electronically resonant conditions, where such unfortunate selection rules do not apply. Nonetheless, control experiments based on spectroscopic line shapes, signal phases, and sample concentrations are conducted to rule out significant contributions from cascades of third-order processes. Theoretical calculations are further used to estimate the relative intensities of the direct and cascaded responses. Overall, the control experiments and model calculations presented in this

  3. Femtosecond stimulated Raman spectroscopy by six-wave mixing

    SciTech Connect

    Molesky, Brian P.; Guo, Zhenkun; Moran, Andrew M.

    2015-06-07

    Femtosecond Stimulated Raman Spectroscopy (FSRS) is motivated by the knowledge of the molecular geometry changes that accompany sub-picosecond chemical reactions. The detection of vibrational resonances throughout the entire fingerprint region of the spectrum with sub-100-fs delay precision is fairly straightforward to accomplish with the FSRS technique. Despite its utility, FSRS must contend with substantial technical challenges that stem from a large background of residual laser light and lower-order nonlinearities when all laser pulses are electronically resonant with the equilibrium system. In this work, a geometry based on five incident laser beams is used to eliminate much of this undesired background in experiments conducted on metmyoglobin. Compared to a three-beam FSRS geometry with all electronically resonant laser pulses, the five-beam approach described here offers major improvements in the data acquisition rate, sensitivity, and background suppression. The susceptibility of the five-beam geometry to experimental artifacts is investigated using control experiments and model calculations. Of particular concern are undesired cascades of third-order nonlinearities, which are known to challenge FSRS measurements carried out on electronically off-resonant systems. It is generally understood that “forbidden” steps in the desired nonlinear optical processes are the origin of the problems encountered under off-resonant conditions. In contrast, the present experiments are carried out under electronically resonant conditions, where such unfortunate selection rules do not apply. Nonetheless, control experiments based on spectroscopic line shapes, signal phases, and sample concentrations are conducted to rule out significant contributions from cascades of third-order processes. Theoretical calculations are further used to estimate the relative intensities of the direct and cascaded responses. Overall, the control experiments and model calculations presented in

  4. Raman spectroscopy for the characterization of algal cells

    NASA Astrophysics Data System (ADS)

    Samek, Ota; Jonáš, Alexandr; Pilát, Zdeněk; Zemánek, Pavel; Nedbal, Ladislav; Tříska, Jan; Kotas, Petr; Trtílek, Martin

    2010-12-01

    Raman spectroscopy can elucidate fundamental questions about intercellular variability and what governs it. Moreover, knowing the metabolic response on single cell level this can significantly contribute to the study and use of microalgae in systems biology and biofuel technology. Raman spectroscopy is capable to measure nutrient dynamics and metabolism in vivo, in real-time, label free making it possible to monitor/evaluate population variability. Also, degree of unsaturation of the algae oil (iodine value) can be measured using Raman spectra obtained from single microalgae. The iodine value is the determination of the amount of unsaturation contained in fatty acids (in the form of double bonds). Here we demonstrate the capacity of the spatially resolved Raman microspectroscopy to determine the effective iodine value in lipid storage bodies of individual living algal cells. We employed the characteristic peaks in the Raman scattering spectra at 1,656 cm-1 (cis C=C stretching mode) and 1,445 cm-1 (CH2 scissoring mode) as the markers defining the ratio of unsaturated-to-saturated carbon-carbon bonds of the fatty acids in the algal lipids.

  5. Raman spectroscopy of Bacillus thuringiensis physiology and inactivation

    NASA Astrophysics Data System (ADS)

    Morrow, J. B.; Almeida, J.; Cole, K. D.; Reipa, V.

    2012-12-01

    The ability to detect spore contamination and inactivation is relevant to developing and determining decontamination strategy success for food and water safety. This study was conducted to develop a systematic comparison of nondestructive vibrational spectroscopy techniques (Surface-Enhanced Raman Spectroscopy, SERS, and normal Raman) to determine indicators of Bacillus thuringiensis physiology (spore, vegetative, outgrown, germinated and inactivated spore forms). SERS was found to provide better resolution of commonly utilized signatures of spore physiology (dipicolinic acid at 1006 cm-1 and 1387 cm-1) compared to normal Raman and native fluorescence indigenous to vegetative and outgrown cell samples was quenched in SERS experiment. New features including carotenoid pigments (Raman features at 1142 cm-1, 1512 cm-1) were identified for spore cell forms. Pronounced changes in the low frequency region (300 cm-1 to 500 cm-1) in spore spectra occurred upon germination and inactivation (with both free chlorine and by autoclaving) which is relevant to guiding decontamination and detection strategies using Raman techniques.

  6. Spatially offset Raman spectroscopy (SORS) for liquid screening

    NASA Astrophysics Data System (ADS)

    Loeffen, Paul W.; Maskall, Guy; Bonthron, Stuart; Bloomfield, Matthew; Tombling, Craig; Matousek, Pavel

    2011-11-01

    Recently, Spatially Offset Raman Spectroscopy (SORS) has been discussed as a novel method for the screening of liquids, aerosols and gels (LAGs) at airports and for other security applications. SORS is an optical spectroscopic method which enables the precise chemical identification of substances from a reference list and, due to the rich spectral information, has an inherently high probability of detection and low false alarm rate. The method is generally capable of screening substances inside non-metallic containers such as plastic and glass bottles. SORS is typically successful through opaque plastic and coloured glass, which are often challenging for conventional backscatter Raman spectroscopy. SORS is performed in just a few seconds by shining a laser light onto the container and then measuring the Raman signal at the excitation point but also at one or more offset positions. Each measurement has different relative orthogonal contributions from the container and contents Raman spectra, so that, with no prior knowledge, the pure Raman spectra of both the container and contents can be extracted - either by scaled subtraction or via multivariate statistical methods in an automated process. In this paper, the latest results will be described from a prototype SORS device designed for aviation security and the advantages and limitations of SORS will be discussed.

  7. Characterization of a superlubricity nanometer interface by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Shi, Yunsheng; Yang, Xing; Liu, Bingqi; Dong, Hualai; Zheng, Quanshui

    2016-08-01

    Despite being known for almost two decades, the use of micro-/nano-electromechanical systems in commercial applications remains a challenge because of stiction, friction, and the wear of the interface. Superlubricity may be the solution to these challenges. In this paper, we study factors affecting the realization of superlubricity. Raman spectroscopy and other methods were used to characterize a graphite interface which can realize superlubricity and another graphite interface which cannot realize superlubricity. Raman spectra of the interfaces were obtained with the mapping mode and then processed to obtain the Raman images of the characteristic peaks. The Raman spectra provided the distribution of the surface defects and probed defects. Combined with atomic force microscopy and x-ray photoelectron spectroscopy, the Raman spectra show that the sp3 carbons and carbon–oxygen bond stuck at the edge of the graphite mesa are some of the determinants of large-area superlubricity realization. The characterization results can also be used to understand the friction and wear of large-area superlubricity, which are important for development and application of superlubricity. Furthermore, the methods used in this study are useful techniques and tools for the mechanism analysis of other nanometer interfaces.

  8. Bladder cancer diagnosis during cystoscopy using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Grimbergen, M. C. M.; van Swol, C. F. P.; Draga, R. O. P.; van Diest, P.; Verdaasdonk, R. M.; Stone, N.; Bosch, J. H. L. R.

    2009-02-01

    Raman spectroscopy is an optical technique that can be used to obtain specific molecular information of biological tissues. It has been used successfully to differentiate normal and pre-malignant tissue in many organs. The goal of this study is to determine the possibility to distinguish normal tissue from bladder cancer using this system. The endoscopic Raman system consists of a 6 Fr endoscopic probe connected to a 785nm diode laser and a spectral recording system. A total of 107 tissue samples were obtained from 54 patients with known bladder cancer during transurethral tumor resection. Immediately after surgical removal the samples were placed under the Raman probe and spectra were collected and stored for further analysis. The collected spectra were analyzed using multivariate statistical methods. In total 2949 Raman spectra were recorded ex vivo from cold cup biopsy samples with 2 seconds integration time. A multivariate algorithm allowed differentiation of normal and malignant tissue with a sensitivity and specificity of 78,5% and 78,9% respectively. The results show the possibility of discerning normal from malignant bladder tissue by means of Raman spectroscopy using a small fiber based system. Despite the low number of samples the results indicate that it might be possible to use this technique to grade identified bladder wall lesions during endoscopy.

  9. Characterization of a superlubricity nanometer interface by Raman spectroscopy.

    PubMed

    Shi, Yunsheng; Yang, Xing; Liu, Bingqi; Dong, Hualai; Zheng, Quanshui

    2016-08-12

    Despite being known for almost two decades, the use of micro-/nano-electromechanical systems in commercial applications remains a challenge because of stiction, friction, and the wear of the interface. Superlubricity may be the solution to these challenges. In this paper, we study factors affecting the realization of superlubricity. Raman spectroscopy and other methods were used to characterize a graphite interface which can realize superlubricity and another graphite interface which cannot realize superlubricity. Raman spectra of the interfaces were obtained with the mapping mode and then processed to obtain the Raman images of the characteristic peaks. The Raman spectra provided the distribution of the surface defects and probed defects. Combined with atomic force microscopy and x-ray photoelectron spectroscopy, the Raman spectra show that the sp(3) carbons and carbon-oxygen bond stuck at the edge of the graphite mesa are some of the determinants of large-area superlubricity realization. The characterization results can also be used to understand the friction and wear of large-area superlubricity, which are important for development and application of superlubricity. Furthermore, the methods used in this study are useful techniques and tools for the mechanism analysis of other nanometer interfaces. PMID:27348089

  10. Investigation for the differentiation process of mouse ES cells by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yoshinori; El-Hagrasy, Maha A.; Shimizu, Eiichi; Saito, Masato; Tamiya, Eiichi

    2012-03-01

    The arrangement of differentiated pluripotent embryonic stem cells into three-dimensional aggregates, which are known as embryonic bodies, is a main step for progressing the embryonic stem cells differentiation. In this work, embryonic stem cells that were directly produced from the hanging drop step as a three-dimensional structure with no further twodimensional differentiation were diagnosed with Raman spectroscopy as a non-invasive and label-free technique. Raman spectroscopy was employed to discriminate between mouse embryonic bodies of different degrees of maturation. EBs were prepared applying the hanging drop method. The Raman scattering measurements were obtained in vitro with a Nanophoton RAMAN-11 micro-spectrometer (Japan: URL: www.nanophoton.jp equipped with an Olympus XLUM Plan FLN 20X/NA= 1.0 objective lens. Spectral data were smoothed, baseline corrected and normalized to the a welldefined intense 1003 cm-1 band (phenylalanine) which is insensitive to changes in conformation or environment. The differentiation process of embryonic stem cells is initiated by the removal of LIF from culture medium. 1, 7 and 17-dayold embryonic stem cells were collected and investigated by Raman spectroscopy. The main differences involve bands which decreased with maturation such as: 784 cm-1 (U, T, C ring br DNA/RNA, O-P-O str); 1177 cm-1 (cytosine, guanine) and 1578 cm-1 (G, A). It was found that with the progress of differentiation the protein content was amplified. The increase of protein to nucleic acid ratio was also previously observed with the progress of the differentiation process. Raman spectroscopy has the potential to distinguish between the Raman signatures of live embryonic stem cells with different degrees of maturation.

  11. The discrimination of fish egg quality and viability by using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ishigaki, Mika; Sato, Hidetoshi

    2014-03-01

    Sexual reproductive body can be produced from a fertilized ovum. Once the ovum is fertilized with sperm, it runs through the cell division, differentiates to all kinds of cells, and goes to make a complete body. However, not all of them are viable and some of them stop to ontogenesis showing the developmental abnormality. In order to discriminate the egg quality, we apply Raman spectroscopy for fish egg. After the measurement, these Raman data are checked up with the information about the eggs can survive or not, and we examine what factors are important in egg components to distinguish between "good quality" and "not good quality". We present the results of assessment of egg quality, and investigate whether Raman spectroscopy can be used to a discriminate of egg quality.

  12. Detection of denatonium benzoate (bitrex) remnants in noncommercial alcoholic beverages by Raman spectroscopy.

    PubMed

    Kwiatkowski, Andrzej; Czerwicka, Małgorzata; Smulko, Janusz; Stepnowski, Piotr

    2014-09-01

    Illegal alcoholic beverages are often introduced into market using cheap technical alcohol, which is contaminated by denatonium benzoate (Bitrex) of very small concentration. Bitrex is the most bitter chemical compound and has to be removed before alcohol consumption. The home-made methods utilize sodium hypochlorite to disintegrate particles of denatonium benzoate in alcohol and to remove bitter taste before trading. In this experimental studies, we propose a novel method that detects in a fast way the remnants of denatonium benzoate in dubious alcohol samples by Raman spectroscopy. This method applies a portable Raman spectrometer of excitation wavelength 785 nm and utilizes the effect of surface-enhanced Raman spectroscopy (SERS) to recognize the suspected alcoholic beverages. High effectiveness (over 98%) of YES/NO classification of the investigated samples was observed when the nonlinear algorithm support vector machine (SVM) was exploited at carefully adjusted detection parameters. The method can identify illicit alcohol within minutes. PMID:24661259

  13. Accelerated Detection of Viral Particles by Combining AC Electric Field Effects and Micro-Raman Spectroscopy

    PubMed Central

    Tomkins, Matthew Robert; Liao, David Shiqi; Docoslis, Aristides

    2015-01-01

    A detection method that combines electric field-assisted virus capture on antibody-decorated surfaces with the “fingerprinting” capabilities of micro-Raman spectroscopy is demonstrated for the case of M13 virus in water. The proof-of-principle surface mapping of model bioparticles (protein coated polystyrene spheres) captured by an AC electric field between planar microelectrodes is presented with a methodology for analyzing the resulting spectra by comparing relative peak intensities. The same principle is applied to dielectrophoretically captured M13 phage particles whose presence is indirectly confirmed with micro-Raman spectroscopy using NeutrAvidin-Cy3 as a labeling molecule. It is concluded that the combination of electrokinetically driven virus sampling and micro-Raman based signal transduction provides a promising approach for time-efficient and in situ detection of viruses. PMID:25580902

  14. Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wehrmeyer, Joseph A.; Osborne, Robin J.; Trinh, Huu P.; Turner, James (Technical Monitor)

    2001-01-01

    Optically accessible, high pressure, hot fire test articles are available at NASA Marshall for use in development of advanced rocket engine propellant injectors. Single laser-pulse ultraviolet (UV) Raman spectroscopy has been used in the past in these devices for analysis of high pressure H2- and CH4-fueled combustion, but relies on an independent pressure measurement in order to provide temperature information. A variation of UV Raman (High Resolution Hydrogen Raman Spectroscopy) is under development and will allow temperature measurement without the need for an independent pressure measurement, useful for flows where local pressure may not be accurately known. The technique involves the use of a spectrometer with good spectral resolution, requiring a small entrance slit for the spectrometer. The H2 Raman spectrum, when created by a narrow linewidth laser source and obtained from a good spectral resolution spectrograph, has a spectral shape related to temperature. By best-fit matching an experimental spectrum to theoretical spectra at various temperatures, a temperature measurement is obtained. The spectral model accounts for collisional narrowing, collisional broadening, Doppler broadening, and collisional line shifting of each Raman line making up the H2 Stokes vibrational Q-branch spectrum. At pressures from atmospheric up to those associated with advanced preburner components (5500 psia), collisional broadening though present does not cause significant overlap of the Raman lines, allowing high resolution H2 Raman to be used for temperature measurements in plumes and in high pressure test articles. Experimental demonstrations of the technique are performed for rich H2-air flames at atmospheric pressure and for high pressure, 300 K H2-He mixtures. Spectrometer imaging quality is identified as being critical for successful implementation of technique.

  15. Optical diagnostic of hepatitis B (HBV) and C (HCV) from human blood serum using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Anwar, Shahzad; Firdous, Shamaraz

    2015-06-01

    Hepatitis is the second most common disease worldwide with half of the cases arising in the developing world. The mortality associated with hepatitis B and C can be reduced if the disease is detected at the early stages of development. The aim of this study was to investigate the potential of Raman spectroscopy as a diagnostic tool to detect biochemical changes accompanying hepatitis progression. Raman spectra were acquired from 20 individuals with six hepatitis B infected patients, six hepatitis C infected patients and eight healthy patients in order to gain an insight into the determination of biochemical changes for early diagnostic. The human blood serum was examined at a 532 nm excitation laser source. Raman characteristic peaks were observed in normal sera at 1006, 1157 and 1513 cm-1, while in the case of hepatitis B and C these peaks were found to be blue shifted with decreased intensity. New Raman peaks appeared in HBV and HCV infected sera at 1194, 1302, 844, 905, 1065 and 1303 cm-1 respectively. A Mat lab subroutine and frequency domain filter program is developed and applied to signal processing of Raman scattering data. The algorithms have been successfully applied to remove the signal noise found in experimental scattering signals. The results show that Raman spectroscopy displays a high sensitivity to biochemical changes in blood sera during disease progression resulting in exceptional prediction accuracy when discriminating between normal and malignant. Raman spectroscopy shows enormous clinical potential as a rapid non-invasive diagnostic tool for hepatitis and other infectious diseases.

  16. FT-Raman spectroscopy study of human breast tissue

    NASA Astrophysics Data System (ADS)

    Bitar Carter, Renata A.; Martin, Airton A.; Netto, Mario M.; Soares, Fernando A.

    2004-07-01

    Optical spectroscopy has been extensively studied as a potential in vivo diagnostic tool to provide information about the chemical and morphologic structure of tissue. Raman Spectroscpy is an inelastic scattering process that can provide a wealth of spectral features that can be related to the specific molecular structure of the sample. This article reports results of an in vitro study of the FT-Raman human breast tissue spectra. An Nd:YAG laser at 1064nm was used as the excitation source in the FT-Raman Spectrometer. The neoplastic human breast samples, both Fibroadenoma and ICD, were obtained during therapeutical routine medical procedures required by the primary disease, and the non-diseased human tissue was obtained in plastic surgery. No sample preparation was needed for the FT-Raman spectra collection. The FT-Raman spectra were recorded from normal, benign (Fibroadenomas) and malignant (IDC-Intraductal Carcinoma) samples, adding up 51 different areas. The main spectral differences of a typical FT-Raman spectra of a Normal (Non-diseased), Fibroadenoma, and Infiltrating Ductal Carcinoma (IDC) breast tissue at the interval of 600 to 1800cm-1, which may differentiate diagnostically the sample, were found in the bands of 1230 to 1295cm-1, 1440 to 1460 cm-1 and 1650 to 1680 cm-1, assigned to the vibrational bands of the carbohydrate-amide III, proteins and lipids, and carbohydrate-amide I, respectively.

  17. Thin Film Substrates from the Raman spectroscopy point of view

    NASA Astrophysics Data System (ADS)

    Gasparov, Lev; Jegorel, Theo; Loetgering, Lars; Middey, Srimanta; Chakhalian, Jak

    2014-03-01

    We have investigated ten standard single crystal substrates of complex oxides on the account of their applicability in the Raman spectroscopy based thin film research. In this study we suggest a spectra normalization procedure that utilises a comparison of the substrate's Raman spectra to those of well-established Raman reference materials. We demonstrate that MgO, LaGaO3, (LaAlO3)0.3(Sr2AlTaO6)0.7 (LSAT), DyScO3, YAlO3, and LaAlO3 can be of potential use for a Raman based thin film research. At the same time TiO2 (rutile), NdGaO3, SrLaAlO4, and SrTiO3 single crystals exhibit multiple phonon modes accompanied by strong Raman background that substantially hinder the Raman based thin film experiments. L.G. acknowledges the support from the National Science Foundation (NSF) Grants DMR-0805073, DMR-0958349, Office of Naval Research award N00014-06-1-0133 and the UNF Terry Presidential Professorship. J. C. was supported by DOD-ARO under Grant No. 0402-172.

  18. Raman Spectroscopy for In-Line Water Quality Monitoring — Instrumentation and Potential

    PubMed Central

    Li, Zhiyun; Deen, M. Jamal; Kumar, Shiva; Selvaganapathy, P. Ravi

    2014-01-01

    Worldwide, the access to safe drinking water is a huge problem. In fact, the number of persons without safe drinking water is increasing, even though it is an essential ingredient for human health and development. The enormity of the problem also makes it a critical environmental and public health issue. Therefore, there is a critical need for easy-to-use, compact and sensitive techniques for water quality monitoring. Raman spectroscopy has been a very powerful technique to characterize chemical composition and has been applied to many areas, including chemistry, food, material science or pharmaceuticals. The development of advanced Raman techniques and improvements in instrumentation, has significantly improved the performance of modern Raman spectrometers so that it can now be used for detection of low concentrations of chemicals such as in-line monitoring of chemical and pharmaceutical contaminants in water. This paper briefly introduces the fundamentals of Raman spectroscopy, reviews the development of Raman instrumentations and discusses advanced and potential Raman techniques for in-line water quality monitoring. PMID:25230309

  19. Tissue measurement using 1064 nm dispersive Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lieber, Chad A.; Wu, Huawen; Yang, William

    2013-03-01

    The use of Raman spectroscopy to provide characterization and diagnosis of biological tissues has shown increasing success in recent years. Most of this work has been performed using near-infrared laser sources such as 785 or 830 nm, in a balance of reduced intrinsic fluorescence in the tissues and quantum efficiency in the silicon detectors often used. However, even at these wavelengths, many tissues still exhibit strong or prohibitive fluorescence, and these wavelengths still cause autofluorescence in many common sampling materials, such as glass. In this study, we demonstrate the use of 1064 nm dispersive Raman spectroscopy for the study of biological tissues. A number of tissues are evaluated using the 1064 nm system and compared with the spectra obtained from a 785 nm system. Sampling materials are similarly compared. These results show that 1064 nm dispersive Raman spectroscopy provides a viable solution for measurement of highly fluorescent biological tissues such as liver and kidney, which are difficult or impossible to extract Raman at 785 nm.

  20. Raman spectroscopy and immunohistochemistry for schwannoma characterization: a case study

    NASA Astrophysics Data System (ADS)

    Neto, Lazaro P. M.; das Chagas, Maurilio J.; Carvalho, Luis Felipe C. S.; Ferreira, Isabelle; dos Santos, Laurita; Haddad, Marcelo; Loddi, Vinicius; Martin, Airton A.

    2016-03-01

    The schwannomas is a tumour of the tissue that covers nerves, called the nerve sheath. Schwannomas are often benign tumors of the Schwan cells, which are the principal glia of the peripheral nervous system (PNS). Preoperative diagnosis of this lesion usually is difficult, therefore, new techniques are being studied as pre surgical evaluation. Among these, Raman spectroscopy, that enables the biochemical identification of the tissue analyzed by their optical properties, may be used as a tool for schwannomas diagnosis. The aim of this study was to discriminate between normal nervous tissue and schwannoma through the confocal Raman spectroscopy and Raman optical fiber-based techniques combined with immunohistochemical analysis. Twenty spectra were analyzed from a normal nerve tissue sample (10) and schwannoma (10) by Holospec f / 1.8 (Kayser Optical Systems) coupled to an optical fiber with a 785nm laser line source. The data were pre-processed and vector normalized. The average analysis and standard deviation was performed associated with cluster analysis. AML, 1A4, CD34, Desmin and S-100 protein markers were used for immunohistochemical analysis. Immunohistochemical analysis was positive only for protein S-100 marker which confirmed the neural schwanomma originality. The immunohistochemistry analysis were important to determine the source of the injury, whereas Raman spectroscopy were able to differentiated tissues types indicating important biochemical changes between normal and benign neoplasia.

  1. Polarized micro-Raman spectroscopy study of pentacene thin films

    NASA Astrophysics Data System (ADS)

    Stenger, Ingrid; Frigout, Alexandre; Tondelier, Denis; Geffroy, Bernard; Ossikovski, Razvigor; Bonnassieux, Yvan

    2009-03-01

    We report on polarized micro-Raman spectroscopy study of two pentacene thin films exhibiting different microstructures: a well-ordered sample and a more disordered one. We have investigated the frequency range of the intramolecular C-H bending modes in the plane of the pentacene molecule and proposed an interpretation of the Raman spectra. The use of symmetry properties of the two intramolecular (uncoupled) modes allowed us to unambiguously identify it among the five main contributions observed in this spectral range. The three other modes were assumed to be resulting from molecular coupling effect owing to their different behavior upon the samples microstructure.

  2. Raman Spectroscopy: A New Proposal for the Detection of Leukemia Using Blood Samples

    SciTech Connect

    Martinez-Espinosa, J. C.; Gonzalez-Solis, J. L.; Miranda-Beltran, M. L.; Soria-Fregoso, C.; Medina-Valtierra, J.; Sanchez-Gomez, R.

    2008-08-11

    The use of Raman spectroscopy to analyze blood biochemistry and hence distinguish between normal and abnormal blood was investigated. The blood samples were obtained from 6 patients who were clinically diagnosed with leukemia and 6 healthy volunteer. The imprint was put under the microscope and several points were chosen for Raman measurement. All spectra were collected at confocal Raman micro-spectroscopy (Renishaw) with NIR 830 nm laser. It is shown that the serum samples from patients with leukemia and from the control group can be discriminated when the multivariate statistical methods of principal component analysis (PCA) and linear discriminated analysis (LDA) is applied to their Raman spectra. The ratios of some band intensities were analyzed and some band ratios were significant and corresponded to proteins, phospholipids, and polysaccharides. In addition, currently the degree of damage to the bone marrow is estimated through biopsies and therefore it is a very procedure painful. The preliminary results suggest that Raman spectroscopy could be a new technique to study the bone marrow using just blood samples.

  3. Fast and sensitive recognition of various explosive compounds using Raman spectroscopy and principal component analysis

    NASA Astrophysics Data System (ADS)

    Hwang, Joonki; Park, Aaron; Chung, Jin Hyuk; Choi, Namhyun; Park, Jun-Qyu; Cho, Soo Gyeong; Baek, Sung-June; Choo, Jaebum

    2013-06-01

    Recently, the development of methods for the identification of explosive materials that are faster, more sensitive, easier to use, and more cost-effective has become a very important issue for homeland security and counter-terrorism applications. However, limited applicability of several analytical methods such as, the incapability of detecting explosives in a sealed container, the limited portability of instruments, and false alarms due to the inherent lack of selectivity, have motivated the increased interest in the application of Raman spectroscopy for the rapid detection and identification of explosive materials. Raman spectroscopy has received a growing interest due to its stand-off capacity, which allows samples to be analyzed at distance from the instrument. In addition, Raman spectroscopy has the capability to detect explosives in sealed containers such as glass or plastic bottles. We report a rapid and sensitive recognition technique for explosive compounds using Raman spectroscopy and principal component analysis (PCA). Seven hundreds of Raman spectra (50 measurements per sample) for 14 selected explosives were collected, and were pretreated with noise suppression and baseline elimination methods. PCA, a well-known multivariate statistical method, was applied for the proper evaluation, feature extraction, and identification of measured spectra. Here, a broad wavenumber range (200- 3500 cm-1) on the collected spectra set was used for the classification of the explosive samples into separate classes. It was found that three principal components achieved 99.3 % classification rates in the sample set. The results show that Raman spectroscopy in combination with PCA is well suited for the identification and differentiation of explosives in the field.

  4. Femtosecond stimulated Raman spectroscopy as a tool to detect molecular vibrations in ground and excited electronic states

    NASA Astrophysics Data System (ADS)

    Gelin, Maxim F.; Domcke, Wolfgang; Rao, B. Jayachander

    2016-05-01

    We give a detailed theoretical analysis of the simplest variant of femtosecond stimulated Raman spectroscopy, where a picosecond Raman pump pulse and a femtosecond Raman probe pulse are applied resonantly to a chromophore in thermal equilibrium in the ground electronic state. We demonstrate that this technique is capable of the detection of dephasing-free Raman-like lines revealing vibrational modes not only in the electronic ground state but also in the excited electronic state of the chromophore. The analytical results obtained with simplifying assumptions for the shape of the laser pulses are substantiated by numerical simulations with realistic laser pulses, employing the equation-of-motion phase-matching approach.

  5. Noninvasive identification of materials inside USP vials with Raman spectroscopy and a Raman spectral library.

    PubMed

    McCreery, R L; Horn, A J; Spencer, J; Jefferson, E

    1998-01-01

    A commercial dispersive Raman spectrometer operating at 785 nm with a CCD detector was used to acquire spectra of USP reference materials inside amber USP vials. The laser and collection beams were directed through the bottom of the vials, resulting in a 60% loss of signal. The Raman shift was calibrated with a 4-acetamidophenol standard, and spectral response was corrected with a luminescent standard. After these corrections, the Raman spectra obtained inside the USP vial and on open powders differed by less than 5%. A spectral library of 309 reference materials was constructed, with spectral acquisition times ranging from 1 to 60 s. Of these, 8% had significant fluorescent background but observable Raman features, while 3% showed only fluorescence. A blind test of 26 unknowns revealed the accuracy of the library search to be 88-96%, depending on search algorithm, and 100% if operator discretion was permitted. The tolerance of the library search to degraded signal-to-noise ratio, resolution, and Raman shift accuracy were tested, and the search was very robust. The results demonstrate that Raman spectroscopy provides a rapid, noninvasive technique for compound identification. PMID:9452960

  6. Rapid detection of benzoyl peroxide in wheat flour by using Raman scattering spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhao, Juan; Peng, Yankun; Chao, Kuanglin; Qin, Jianwei; Dhakal, Sagar; Xu, Tianfeng

    2015-05-01

    Benzoyl peroxide is a common flour additive that improves the whiteness of flour and the storage properties of flour products. However, benzoyl peroxide adversely affects the nutritional content of flour, and excess consumption causes nausea, dizziness, other poisoning, and serious liver damage. This study was focus on detection of the benzoyl peroxide added in wheat flour. A Raman scattering spectroscopy system was used to acquire spectral signal from sample data and identify benzoyl peroxide based on Raman spectral peak position. The optical devices consisted of Raman spectrometer and CCD camera, 785 nm laser module, optical fiber, prober, and a translation stage to develop a real-time, nondestructive detection system. Pure flour, pure benzoyl peroxide and different concentrations of benzoyl peroxide mixed with flour were prepared as three sets samples to measure the Raman spectrum. These samples were placed in the same type of petri dish to maintain a fixed distance between the Raman CCD and petri dish during spectral collection. The mixed samples were worked by pretreatment of homogenization and collected multiple sets of data of each mixture. The exposure time of this experiment was set at 0.5s. The Savitzky Golay (S-G) algorithm and polynomial curve-fitting method was applied to remove the fluorescence background from the Raman spectrum. The Raman spectral peaks at 619 cm-1, 848 cm-1, 890 cm-1, 1001 cm-1, 1234 cm-1, 1603cm-1, 1777cm-1 were identified as the Raman fingerprint of benzoyl peroxide. Based on the relationship between the Raman intensity of the most prominent peak at around 1001 cm-1 and log values of benzoyl peroxide concentrations, the chemical concentration prediction model was developed. This research demonstrated that Raman detection system could effectively and rapidly identify benzoyl peroxide adulteration in wheat flour. The experimental result is promising and the system with further modification can be applicable for more products in near

  7. Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.

    DOEpatents

    Alfano, Robert R.; Wang, Wubao

    2003-05-06

    A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. A low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively.

  8. Cell identification using Raman spectroscopy in combination with optical trapping and microfluidics

    NASA Astrophysics Data System (ADS)

    Krafft, Christoph; Dochow, Sebastian; Beleites, Claudia; Popp, Jürgen

    2014-03-01

    Cell identification by Raman spectroscopy has evolved to be an attractive complement to established optical techniques. Raman activated cell sorting (RACS) offers prospects to complement the widely applied fluorescence activated cell sorting. RACS can be realized by combination with optical traps and microfluidic devices. The progress of RACS is reported for a cellular model system that can be found in peripheral blood of tumor patients. Lymphocytes and erythrocytes were extracted from blood samples. Breast carcinoma derived tumor cells (MCF-7, BT-20) and acute myeloid leukemia cells (OCI-AML3) were grown in cell cultures. First, Raman images were collected from dried cells on calcium fluoride slides. Support vector machines (SVM) classified 99.7% of the spectra to the correct cell type. Second, a 785 nm laser was used for optical trapping of single cells in aqueous buffer and for excitation of the Raman spectrum. SVM distinguished 1210 spectra of tumor and normal cells with a sensitivity of >99.7% and a specificity of >99.5%. Third, a microfluidic glass chip was designed to inject single cells, modify the flow speed, accommodate fibers of an optical trap and sort single cells after Raman based identification with 514 nm for excitation. Forth, the microfluidic chip was fabricated by quartz which improved cell identification results with 785 nm excitation. Here, partial least squares discriminant analysis gave classification rates of 98%. Finally, a Raman-on-chip approach was developed that integrates fibers for trapping, Raman excitation and signal detection in a single compact unit.

  9. Raman spectroscopy investigation of magnetite nanoparticles in ferrofluids

    NASA Astrophysics Data System (ADS)

    Slavov, L.; Abrashev, M. V.; Merodiiska, T.; Gelev, Ch.; Vandenberghe, R. E.; Markova-Deneva, I.; Nedkov, I.

    2010-07-01

    Raman spectroscopy is used to investigate magnetite nanoparticles dispersed in two types of β-cyclodextrin suspensions. An approach is presented for characterization of the magnetic core in liquid surrounding at room temperature and atmospheric pressure. The effect of elevating laser power on the structural stability and chemical composition of magnetite in the ferrofluids is discussed. The data are compared with data from dry by-products from the fluids. Powder samples undergo total phase transition from magnetite to hematite at laser power of 1.95 mW. The same nanoparticles in the fluid undergo transformation at 9 mW, but no hematite positions appear throughout that investigation. The Raman spectra revealed that the main phase of the magnetic core in the fluids is magnetite. That is indicated by a strong and non-diminishing in intensity peak at 670 cm -1. A second phase is present at the nanoparticle's surface with Raman spectroscopy unveiling maghemite-like and small fractions of goethite-like structures. The Fourier transform infrared spectroscopy investigations confirm deviations in the surface structure and also point to the fact that the oxidation process starts at an early stage after formation of the nanoparticles. The analyses of the infrared data also show that β-cyclodextrin molecules retain their cyclic character and the coating does not affect the oxidation process once the particles are evicted from the fluids. A Mössbauer spectroscopy measurement on a ferrofluidic sample is also presented.

  10. [Joint Analyses of Na2SO4 Solution by Laser Induced Breakdown Spectroscopy and Raman Spectroscopy].

    PubMed

    Guo, Jin-jia; Lu, Yuan; Liu, Chun-hao; Zheng, Rong-er

    2016-01-01

    Spectroscopic sensor is becoming an important issue for the deep-sea exploration due to the advantages of multi-specie, multi-phases and stand-off detection. Different approach have been developing in recent years based on LIBS (Laser Induced Breakdown Spectroscopy) and Raman spectroscopy since Raman-LIBS are complementary techniques with the similar components and the capability of molecular and elementary analysis. In this work, we built a LIBS-Raman system and detected Na2SO4 in aqueous solution to evaluate the potential ocean application. With the same laser, spectrometer and detector, a hybrid of Raman and LIBS system was developed to realize the detection of anions and cations in the seawater. The optics was composed by two parts. Raman channel and LIBS channel, and the signal was collected by a Y type optical fiber bundle. The signal from two channels was separated by imaging on different arrays of the CCD detector. The Raman spectra of SO4(2-) and LIBS spectra of Na was successfully detected simultaneously when the pulse energy was above 3.6 mJ. However, due to the strong bremsstrahlung radiation of LIBS, the signal to noise ratio of Raman was significantly decreased as the laser energy increasing. The results manifested the great potential of Raman-LIBS combination for the underwater detection. PMID:27228778

  11. Optical Coherence Tomography and Raman Spectroscopy of the retina

    SciTech Connect

    Evans, J W; Zawadzki, R J; Liu, R; Chan, J; Lane, S; Werner, J S

    2009-01-16

    Imaging the structure and correlating it with the biochemical content of the retina holds promise for fundamental research and for clinical applications. Optical coherence tomography (OCT) is commonly used to image the 3D structure of the retina and while the added functionality of biochemical analysis afforded by Raman scattering could provide critical molecular signatures for clinicians and researchers, there are many technical challenges to combining these imaging modalities. We present an ex vivo OCT microscope combined with Raman spectroscopy capable of collecting morphological and molecular information about a sample simultaneously. The combined instrument will be used to investigate remaining technical challenges to combine these imaging modalities, such as the laser power levels needed to achieve a Raman signal above the noise level without damaging the sample.

  12. Comparison of Raman spectroscopy equipment for tissues and biofluids analysis

    NASA Astrophysics Data System (ADS)

    Khristoforova, Yu. A.; Bratchenko, I. A.; Myakinin, O. O.; Artemyev, D. N.; Zakharov, V. P.

    2016-04-01

    In this study we demonstrate a comparative analysis of blood serum and normal human skin by Raman spectroscopy with application of different spectroscopic equipment. For serum analysis we measure a total concentration of proteins and compared it with intensity of 1002 cm-1 Raman peak. Standard deviation for protein control in blood serum differed from 7.4% to 19% for different spectroscopic setups. For human skin control we used three Raman peaks near 1340, 1450 and 1650 cm-1. Measurements of different skin samples were analyzed on the phase plane to find areas corresponding to the normal skin. Taking into account the different sensitivities of the detected signal with different detectors in the spectral range 810-950 nm we calculated correction coefficients allowed for making comparison of spectral measurements made on different spectrometers with ranging not exceeding 21%.

  13. Surface-enhanced Raman spectroscopy of creatinine in silver colloid

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Chen, Jiesi; Wu, Yanan; Chen, Yanping; Pan, Jianji; Lei, Jinping; Chen, Yongjian; Sun, Liqing; Feng, Shangyuan; Chen, Rong

    2011-11-01

    Surface enhanced Raman spectroscopy (SERS) technology has already made great progress in bio-molecule detection. It can make the target molecules strongly absorbed onto the surface of metal nanoparticles, and then the Raman signal of its own has been greatly enhanced through physical and chemical enhancement mechanisms. We report the SERS spectra of creatinine in silver colloid, and study the silver colloid enhanced effects on the Raman scattering of creatinine. We can also find that creatinine concentration is linearly related to its SERS peak intensity and the detection limit of creatinine silver sol is found to be 10 mg/dl. In conclusion, we can observe that the silver colloid has very good enhanced effects for the creatinine. The potential applications of SERS in quantitative measurement of the creatinine liquor are demonstrated. The result shows that the SERS approach would provide a unique and fast test method for creatinine detection.

  14. Surface-enhanced Raman spectroscopy of creatinine in silver colloid

    NASA Astrophysics Data System (ADS)

    Wang, Yue; Chen, Jiesi; Wu, Yanan; Chen, Yanping; Pan, Jianji; Lei, Jinping; Chen, Yongjian; Sun, Liqing; Feng, Shangyuan; Chen, Rong

    2012-03-01

    Surface enhanced Raman spectroscopy (SERS) technology has already made great progress in bio-molecule detection. It can make the target molecules strongly absorbed onto the surface of metal nanoparticles, and then the Raman signal of its own has been greatly enhanced through physical and chemical enhancement mechanisms. We report the SERS spectra of creatinine in silver colloid, and study the silver colloid enhanced effects on the Raman scattering of creatinine. We can also find that creatinine concentration is linearly related to its SERS peak intensity and the detection limit of creatinine silver sol is found to be 10 mg/dl. In conclusion, we can observe that the silver colloid has very good enhanced effects for the creatinine. The potential applications of SERS in quantitative measurement of the creatinine liquor are demonstrated. The result shows that the SERS approach would provide a unique and fast test method for creatinine detection.

  15. Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy.

    PubMed

    Mlynáriková, Katarína; Samek, Ota; Bernatová, Silvie; Růžička, Filip; Ježek, Jan; Hároniková, Andrea; Šiler, Martin; Zemánek, Pavel; Holá, Veronika

    2015-01-01

    Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar. PMID:26610516

  16. Influence of Culture Media on Microbial Fingerprints Using Raman Spectroscopy

    PubMed Central

    Mlynáriková, Katarína; Samek, Ota; Bernatová, Silvie; Růžička, Filip; Ježek, Jan; Hároniková, Andrea; Šiler, Martin; Zemánek, Pavel; Holá, Veronika

    2015-01-01

    Raman spectroscopy has a broad range of applications across numerous scientific fields, including microbiology. Our work here monitors the influence of culture media on the Raman spectra of clinically important microorganisms (Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Candida albicans). Choosing an adequate medium may enhance the reproducibility of the method as well as simplifying the data processing and the evaluation. We tested four different media per organism depending on the nutritional requirements and clinical usage directly on a Petri dish. Some of the media have a significant influence on the microbial fingerprint (Roosvelt-Park Institute Medium, CHROMagar) and should not be used for the acquisition of Raman spectra. It was found that the most suitable medium for microbiological experiments regarding these organisms was Mueller-Hinton agar. PMID:26610516

  17. Evaluating lignocellulosic biomass, its derivatives, and downstream products with Raman spectroscopy.

    PubMed

    Lupoi, Jason S; Gjersing, Erica; Davis, Mark F

    2015-01-01

    The creation of fuels, chemicals, and materials from plants can aid in replacing products fabricated from non-renewable energy sources. Before using biomass in downstream applications, it must be characterized to assess chemical traits, such as cellulose, lignin, or lignin monomer content, or the sugars released following an acid or enzymatic hydrolysis. The measurement of these traits allows researchers to gage the recalcitrance of the plants and develop efficient deconstruction strategies to maximize yields. Standard methods for assessing biomass phenotypes often have experimental protocols that limit their use for screening sizeable numbers of plant species. Raman spectroscopy, a non-destructive, non-invasive vibrational spectroscopy technique, is capable of providing qualitative, structural information and quantitative measurements. Applications of Raman spectroscopy have aided in alleviating the constraints of standard methods by coupling spectral data with multivariate analysis to construct models capable of predicting analytes. Hydrolysis and fermentation products, such as glucose and ethanol, can be quantified off-, at-, or on-line. Raman imaging has enabled researchers to develop a visual understanding of reactions, such as different pretreatment strategies, in real-time, while also providing integral chemical information. This review provides an overview of what Raman spectroscopy is, and how it has been applied to the analysis of whole lignocellulosic biomass, its derivatives, and downstream process monitoring. PMID:25941674

  18. Evaluating lignocellulosic biomass, its derivatives, and downstream products with Raman spectroscopy

    DOE PAGESBeta

    Lupoi, Jason S.; Gjersing, Erica; Davis, Mark F.

    2015-04-20

    The creation of fuels, chemicals, and materials from plants can aid in replacing products fabricated from non-renewable energy sources. Before using biomass in downstream applications, it must be characterized to assess chemical traits, such as cellulose, lignin, or lignin monomer content, or the sugars released following an acid or enzymatic hydrolysis. The measurement of these traits allows researchers to gage the recalcitrance of the plants and develop efficient deconstruction strategies to maximize yields. Standard methods for assessing biomass phenotypes often have experimental protocols that limit their use for screening sizeable numbers of plant species. Raman spectroscopy, a non-destructive, non-invasive vibrationalmore » spectroscopy technique, is capable of providing qualitative, structural information and quantitative measurements. Applications of Raman spectroscopy have aided in alleviating the constraints of standard methods by coupling spectral data with multivariate analysis to construct models capable of predicting analytes. Hydrolysis and fermentation products, such as glucose and ethanol, can be quantified off-, at-, or on-line. Raman imaging has enabled researchers to develop a visual understanding of reactions, such as different pretreatment strategies, in real-time, while also providing integral chemical information. Finally, this review provides an overview of what Raman spectroscopy is, and how it has been applied to the analysis of whole lignocellulosic biomass, its derivatives, and downstream process monitoring.« less

  19. Evaluating lignocellulosic biomass, its derivatives, and downstream products with Raman spectroscopy

    SciTech Connect

    Lupoi, Jason S.; Gjersing, Erica; Davis, Mark F.

    2015-04-20

    The creation of fuels, chemicals, and materials from plants can aid in replacing products fabricated from non-renewable energy sources. Before using biomass in downstream applications, it must be characterized to assess chemical traits, such as cellulose, lignin, or lignin monomer content, or the sugars released following an acid or enzymatic hydrolysis. The measurement of these traits allows researchers to gage the recalcitrance of the plants and develop efficient deconstruction strategies to maximize yields. Standard methods for assessing biomass phenotypes often have experimental protocols that limit their use for screening sizeable numbers of plant species. Raman spectroscopy, a non-destructive, non-invasive vibrational spectroscopy technique, is capable of providing qualitative, structural information and quantitative measurements. Applications of Raman spectroscopy have aided in alleviating the constraints of standard methods by coupling spectral data with multivariate analysis to construct models capable of predicting analytes. Hydrolysis and fermentation products, such as glucose and ethanol, can be quantified off-, at-, or on-line. Raman imaging has enabled researchers to develop a visual understanding of reactions, such as different pretreatment strategies, in real-time, while also providing integral chemical information. Finally, this review provides an overview of what Raman spectroscopy is, and how it has been applied to the analysis of whole lignocellulosic biomass, its derivatives, and downstream process monitoring.

  20. Evaluating Lignocellulosic Biomass, Its Derivatives, and Downstream Products with Raman Spectroscopy

    PubMed Central

    Lupoi, Jason S.; Gjersing, Erica; Davis, Mark F.

    2015-01-01

    The creation of fuels, chemicals, and materials from plants can aid in replacing products fabricated from non-renewable energy sources. Before using biomass in downstream applications, it must be characterized to assess chemical traits, such as cellulose, lignin, or lignin monomer content, or the sugars released following an acid or enzymatic hydrolysis. The measurement of these traits allows researchers to gage the recalcitrance of the plants and develop efficient deconstruction strategies to maximize yields. Standard methods for assessing biomass phenotypes often have experimental protocols that limit their use for screening sizeable numbers of plant species. Raman spectroscopy, a non-destructive, non-invasive vibrational spectroscopy technique, is capable of providing qualitative, structural information and quantitative measurements. Applications of Raman spectroscopy have aided in alleviating the constraints of standard methods by coupling spectral data with multivariate analysis to construct models capable of predicting analytes. Hydrolysis and fermentation products, such as glucose and ethanol, can be quantified off-, at-, or on-line. Raman imaging has enabled researchers to develop a visual understanding of reactions, such as different pretreatment strategies, in real-time, while also providing integral chemical information. This review provides an overview of what Raman spectroscopy is, and how it has been applied to the analysis of whole lignocellulosic biomass, its derivatives, and downstream process monitoring. PMID:25941674

  1. Molecule-surface interactions probed by optimized surface-enhanced coherent Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Voronine, Dmitri; Sinyukov, Alexander; Hua, Xia; Zhang, Guowan; Yang, Wenlong; Wang, Kai; Jha, Pankaj; Welch, George; Sokolov, Alexei; Scully, Marlan

    2012-06-01

    Nanoscale molecular sensing is carried out using a time-resolved coherent anti-Stokes Raman scattering (CARS) spectroscopy with optimized laser pulse configurations. This novel technique combines the advantages of an improved spectral resolution, suppressed non-resonant background and near-field surface enhancement of the Raman signal. We detect two species of pyridine in a vicinity of aggregated gold nanoparticles and measure their vibrational dephasing times which reveal the effects of surface environment and molecule-surface interactions on the ultrafast molecular dynamics. This technique may be applied to a variety of artificial and biological systems and complex molecular mixtures and has a potential for nanophotonic sensing applications.

  2. On optical depth profiling using confocal Raman spectroscopy.

    PubMed

    Freebody, N A; Vaughan, A S; Macdonald, A M

    2010-04-01

    Until 2006 the performance of confocal Raman spectroscopy depth profiling was typically described and modeled through the application of geometrical optics, including refraction at the surface, to explain the degree of resolution and the precise form of the depth profile obtained from transparent and semicrystalline materials. Consequently a range of techniques, physical and analytical, was suggested to avoid the errors thus encountered in order to improve the practice of Raman spectroscopy, if not the understanding of the underlying mechanisms. These approaches were completely unsuccessful in accounting for the precise form of the depth profile, the fact that spectra obtained from laminated samples always contain characteristic peaks from all materials present both well above and below the focal point and that spectra can be obtained when focused some 40 mum above the sample surface. This paper provides further evidence that the physical processes underlying Raman spectroscopy are better modeled and explained through the concept of an extended illuminated volume contributing to the final Raman spectrum and modeled through a photon scattering approach rather than a point focus ray optics approach. The power of this numerical model lies in its ability to incorporate, simultaneously, the effects of degree of refraction at the surface (whether using a dry or oil objective lens), the degree of attenuation due to scatter by the bulk of the material, the Raman scattering efficiency of the material, and surface roughness effects. Through this we are now able to explain why even removing surface aberration and refraction effects through the use of oil immersion objective lenses cannot reliably ensure that the material sampled is only that at or close to the point of focus of the laser. Furthermore we show that the precise form of the depth profile is affected by the degree of flatness of the surface of the sample. Perhaps surprisingly, we show that the degree of flatness

  3. Tip-enhanced Raman spectroscopy and related techniques in studies of biological materials

    NASA Astrophysics Data System (ADS)

    Schmid, Thomas; Sebesta, Aleksandar; Stadler, Johannes; Opilik, Lothar; Balabin, Roman M.; Zenobi, Renato

    2010-02-01

    Biological materials can be highly heterogeneous at the nanometer scale. The investigation of nanostructures is often hampered by the low spatial resolution (e.g. spectroscopic techniques) or very little chemical information (e.g. atomic force microscopy (AFM), scanning tunneling microscopy (STM)) provided by analytical techniques. Our research focuses on combined instruments, which allow the analysis of the exactly same area of a sample by complementary techniques, such as AFM and Raman spectroscopy. Tip-enhanced Raman spectroscopy (TERS) combines the high spatial resolution of AFM or STM with the chemical information provided by Raman spectroscopy. The technique is based on enhancement effects known from surface-enhanced Raman scattering (SERS). In TERS the enhancing metallic nanostructure is brought to the sample by an AFM or STM tip. With a TERS-active tip, enhanced Raman signals can be generated from a sample area as small as 10-50 nm in diameter. AFM analysis of bacterial biofilms has demonstrated their heterogeneity at the nanometer scale, revealing a variety of nanostructures such as pili, flagella, and extracelullar polymers. TERS measurements of the biopolymers alginate and cytochrome c have yielded spectroscopic fingerprints even of such weak Raman scatterers, which in future can allow their localization in complex matrices. Furthermore, biofilms of the bacterium Halomonas meridiana were studied, which was found to be involved in the generation of the mineral dolomite. Only combined AFM-Raman analysis was able to identify the nanoglobules found in laboratory cultures of H. meridiana as dolomite nanoparticles. Our combined setups are and will be applied to the investigation of biofilms, fish spermatozoa as well as biological membranes.

  4. In vivo confocal Raman spectroscopy study of the vitamin A derivative perfusion through human skin

    NASA Astrophysics Data System (ADS)

    dos Santos, Laurita; Téllez Soto, Claudio A.; Favero, Priscila P.; Martin, Airton A.

    2016-03-01

    In vivo confocal Raman spectroscopy is a powerful non-invasive technique able to analyse the skin constituents. This technique was applied to transdermal perfusion studies of the vitamin A derivative in human skin. The composition of the stratum corneum (lipid bilayer) is decisive for the affinity and transport of the vitamin through skin. The vitamin A is significantly absorbed by human skin when applied with water in oil emulsion or hydro-alcoholic gel. The purpose of this study is to elucidate the behaviour of vitamin A derivative into human skin without the presence of enhancers. The results showed that the intensity band of the derivative (around 1600 cm-1), which represents the -C=O vibrational mode, was detected in different stratum corneum depths (up to 20 μm). This Raman peak of vitamin A derivative has non-coincident band with the Raman spectra of the skin epidermis, demonstrating that compound penetrated in forearm skin.

  5. Raman Spectroscopy-Compatible Inactivation Method for Pathogenic Endospores▿

    PubMed Central

    Stöckel, S.; Schumacher, W.; Meisel, S.; Elschner, M.; Rösch, P.; Popp, J.

    2010-01-01

    Micro-Raman spectroscopy is a fast and sensitive tool for the detection, classification, and identification of biological organisms. The vibrational spectrum inherently serves as a fingerprint of the biochemical composition of each bacterium and thus makes identification at the species level, or even the subspecies level, possible. Therefore, microorganisms in areas susceptible to bacterial contamination, e.g., clinical environments or food-processing technology, can be sensed. Within the scope of point-of-care-testing also, detection of intentionally released biosafety level 3 (BSL-3) agents, such as Bacillus anthracis endospores, or their products is attainable. However, no Raman spectroscopy-compatible inactivation method for the notoriously resistant Bacillus endospores has been elaborated so far. In this work we present an inactivation protocol for endospores that permits, on the one hand, sufficient microbial inactivation and, on the other hand, the recording of Raman spectroscopic signatures of single endospores, making species-specific identification by means of highly sophisticated chemometrical methods possible. Several physical and chemical inactivation methods were assessed, and eventually treatment with 20% formaldehyde proved to be superior to the other methods in terms of sporicidal capacity and information conservation in the Raman spectra. The latter fact has been verified by successfully using self-learning machines (such as support vector machines or artificial neural networks) to identify inactivated B. anthracis-related endospores with adequate accuracies within the range of the limited model database employed. PMID:20208030

  6. Screening and classification of ordinary chondrites by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Pittarello, Lidia; Baert, Kitty; Debaille, Vinciane; Claeys, Philippe

    2015-10-01

    Classification of ordinary chondrite meteorites generally implies (1) determining the chemical group by the composition in endmembers of olivine and pyroxene, and (2) identifying the petrologic group by microstructural features. The composition of olivine and pyroxene is commonly obtained by microprobe analyses or oil immersion of mineral separates. We propose Raman spectroscopy as an alternative technique to determine the endmember content of olivine and pyroxene in ordinary chondrites, by using the link between the wavelength shift of selected characteristic peaks in the spectra of olivine and pyroxene and the Mg/Fe ratio in these phases. The existing correlation curve has been recalculated from the Raman spectrum of reference minerals of known composition and further refined for the range of chondritic compositions. Although the technique is not as accurate as the microprobe for determining the composition of olivine and pyroxene, for most of the samples the chemical group can be easily determined by Raman spectroscopy. Blind tests with ordinary chondrites of different provenance, weathering, and shock stages have confirmed the potential of the method. Therefore, we suggest that a preliminary screening and the classification of most of the equilibrated ordinary chondrites can be carried out using an optical microscope equipped with a Raman spectrometer.

  7. Advances in Raman spectroscopy for explosive identification in aviation security

    NASA Astrophysics Data System (ADS)

    Santillán, Javier D.; Brown, Christopher D.; Jalenak, Wayne

    2007-04-01

    In the operational airport environment, the rapid identification of potentially hazardous materials such as improvised explosive devices, chemical warfare agents and flammable and explosive liquids is increasingly critical. Peroxide-based explosives pose a particularly insidious threat because they can be made from commonly available and relatively innocuous household chemicals, such as bleach and hydrogen peroxide. Raman spectroscopy has been validated as a valuable tool for rapid identification of chemicals, explosives, and narcotics and their precursors while allowing "line-of-sight" interrogation through bottles or other translucent containers. This enables safe identification of both precursor substances, such as acetone, and end-products, such as TATP, without direct sampling, contamination and exposure by security personnel. To date, Raman systems have been laboratory-based, requiring careful operation and maintenance by technology experts. The capital and ongoing expenses of these systems is also significant. Recent advances in Raman component technologies have dramatically reduced the footprint and cost, while improving the reliability and ease of use of Raman spectroscopy systems. Such technologies are not only bringing the lab to the field, but are also protecting civilians and security personnel in the process.

  8. Breast cancer diagnosis using FT-RAMAN spectroscopy

    NASA Astrophysics Data System (ADS)

    Bitar, Renata A.; Martin, Airton A.; Criollo, Carlos J. T.; Ramalho, Leandra N. Z.

    2005-04-01

    In this study FT-RAMAN spectra of breast tissue from 35 patients were obtained and separated into nine groups for histopathologic analysis, which are as follows: normal breast tissue, fibrocystic condition, in situ ductal carcinoma, in situ ductal carcinoma with necrosis, infiltrate ductal carcinoma, infiltrate inflammatory ductal carcinoma, infiltrate medullar ductal carcinoma, infiltrate colloid ductal carcinoma, and infiltrate lobular carcinoma. Using spectrum averages taken from each group a qualitative analysis was performed to compare these molecular compositions to those known to be present in abnormal concentrations in pathological situations, e.g. the development of desmoplastic lesions with a stroma of dense collagen in tumoral breast tissues which substitute adipose stroma of non-diseased breast tissue. The band identified as amino acids, offered basis for observation in the existence of alterations in the proteins, thus proving Raman Spectroscopic capacity in identification of primary structures of proteins; secondary protein structure was also identified through the peptic links, Amide I and Amide III, which have also been identified by various authors. Alterations were also identified in the peaks and bandwidths of nucleic acids demonstrating the utilization of Raman Spectroscopy in the analysis of the cells nucleus manifestations. All studies involving Raman Spectroscopy and breast cancer have shown excellent result reliability and therefore a basis for the technical theory.

  9. Challenges Analyzing Gypsum on Mars by Raman Spectroscopy.

    PubMed

    Marshall, Craig P; Olcott Marshall, Alison

    2015-09-01

    Raman spectroscopy can provide chemical information about organic and inorganic substances quickly and nondestructively with little to no sample preparation, thus making it an ideal instrument for Mars rover missions. The ESA ExoMars planetary mission scheduled for launch in 2018 will contain a miniaturized Raman spectrometer (RLS) as part of the Pasteur payload operating with a continuous wave (CW) laser emitting at 532 nm. In addition, NASA is independently developing two miniaturized Raman spectrometers for the upcoming Mars 2020 rover mission, one of which is a remote (stand-off) Raman spectrometer that uses a pulse-gated 532 nm excitation system (SuperCam). The other is an in situ Raman spectrometer that employs a CW excitation laser emitting at 248.6 nm (SHERLOC). Recently, it has been shown with analyses by Curiosity that Gale Crater contains significantly elevated concentrations of transition metals such as Cr and Mn. Significantly, these transition metals are known to undergo fluorescence emission in the visible portion of the electromagnetic spectrum. Consequently, samples containing these metals could be problematic for the successful acquisition of fluorescence-free Raman spectra when using a CW 532 nm excitation source. Here, we investigate one analog environment, with a similar mineralogy and sedimentology to that observed in martian environments, as well as elevated Cr contents, to ascertain the best excitation wavelength to successfully collect fluorescence-free spectra from Mars-like samples. Our results clearly show that CW near-infrared laser excitation emitting at 785 nm is better suited to the collection of fluorescence-free Raman spectra than would be a CW laser emitting at 532 nm. PMID:26317670

  10. In Vivo Blood Glucose Quantification Using Raman Spectroscopy

    PubMed Central

    Shao, Jingwei; Lin, Manman; Li, Yongqing; Li, Xue; Liu, Junxian; Liang, Jianpin; Yao, Huilu

    2012-01-01

    We here propose a novel Raman spectroscopy method that permits the noninvasive measurement of blood glucose concentration. To reduce the effects of the strong background signals produced by surrounding tissue and to obtain the fingerprint Raman lines formed by blood analytes, a laser was focused on the blood in vessels in the skin. The Raman spectra were collected transcutaneously. Characteristic peaks of glucose (1125 cm-1) and hemoglobin (1549 cm-1) were observed. Hemoglobin concentration served as an internal standard, and the ratio of the peaks that appeared at 1125 cm-1 and 1549 cm-1 peaks was used to calculate the concentration of blood glucose. We studied three mouse subjects whose blood glucose levels became elevated over a period of 2 hours using a glucose test assay. During the test, 25 Raman spectra were collected transcutaneously and glucose reference values were provided by a blood glucose meter. Results clearly showed the relationship between Raman intensity and concentration. The release curves were approximately linear with a correlation coefficient of 0.91. This noninvasive methodology may be useful for the study of blood glucose in vivo. PMID:23133555

  11. NIR Raman spectroscopy in medicine and biology: results and aspects

    NASA Astrophysics Data System (ADS)

    Schrader, B.; Dippel, B.; Erb, I.; Keller, S.; Löchte, T.; Schulz, H.; Tatsch, E.; Wessel, S.

    1999-05-01

    Analyses of biomaterial by 'classical' Raman spectroscopy with excitation in the visible range has not been possible since the fluorescence of many essential constituents of all animal and plant cells and tissues overlays the Raman spectra completely. Fluorescence, however, is virtually avoided, when Raman spectra are excited with the Nd : YAG laser line at 1064 nm. Within seven dissertations we explored different fields of potential applications to medical diagnostics. Identification and qualification of tissues and cells is possible. Tumors show small but significant differences to normal tissues; in order to develop a reliable tool for tumor diagnostics more research is necessary, especially a collection of reference spectra in a data bank is needed. Raman spectra of biomineralization structures in teeth and bones show pathological tissues as well as the development of new mineralized structures. NIR Raman spectra of flowers, leaves, and fruit show, without special preparation, their constituents: alkaloids, the essential oils, natural dyes, flavors, spices and drugs. They allow application to taxonomy, optimizing plant breeding and control of food.

  12. Biophysical basis for noninvasive skin cancer detection using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Feng, Xu; Moy, Austin J.; Markey, Mia K.; Fox, Matthew C.; Reichenberg, Jason S.; Tunnell, James W.

    2016-03-01

    Raman spectroscopy (RS) is proving to be a valuable tool for real time noninvasive skin cancer detection via optical fiber probe. However, current methods utilizing RS for skin cancer diagnosis rely on statistically based algorithms to provide tissue classification and do not elucidate the underlying biophysical changes of skin tissue. Therefore, we aim to use RS to explore skin biochemical and structural characteristics and then correlate the Raman spectrum of skin tissue with its disease state. We have built a custom confocal micro-Raman spectrometer system with an 830nm laser light. The high resolution capability of the system allows us to measure spectroscopic features from individual tissue components in situ. Raman images were collected from human skin samples from Mohs surgical biopsy, which were then compared with confocal laser scanning, two-photon fluorescence and hematoxylin and eosin-stained images to develop a linear model of skin tissue Raman spectra. In this model, macroscopic tissue spectra obtained from RS fiber probe were fit into a linear combination of individual basis spectra of primary skin constituents. The fit coefficient of the model explains the biophysical changes spanning a range of normal and various disease states. The model allows for determining parameters similar to that a pathologist is familiar reading and will be a significant guidance in developing RS diagnostic decision schemes.

  13. Exploitation of resonance Raman spectroscopy as a remote chemical sensor

    SciTech Connect

    Sedlacek, A.J.; Chen, C.L.

    1995-08-01

    We have discussed recent experimental results using a resonance-Raman-based LIDAR system as a remote chemical sensor. This spectroscopy has the fundamental advantage that it is based on optical fingerprints that are insensitive to environmental perturbations. By taking advantage of resonance enhancement, which 6 orders-of-magnitude, can be as large as 4 to an increased sensing range for a given chemical concentration or lower detection limit for a given stand-off distance can be realized. The success discussed above can in part be traced back to the use of new state-of-the-art technologies which, only recently, have allowed the phenomenon of resonance-enhanced Raman spectroscopy to be fully exploited as a remote chemical sensor platform. Since many chemicals have electronic transitions in the UV/IS, it is expected that many will have pronounced resonance enhancements.

  14. Carbon Raman Spectroscopy of 36 Inter-Planetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Busemann, H.; Nittler, L. R.; Davidson, J.; Franchi, I. A.; Messenger, S.; Nakamura-Messenger, K.; Palma, R. L.; Pepin, R. O.

    2009-01-01

    Carbon Raman spectroscopy is a useful tool to determine the degree of order of organic material (OM) in extra-terrestrial matter. As shown for meteoritic OM [e.g., 2], peak parameters of D and G bands are a measure of thermal alteration, causing graphitization (order), and amorphization, e.g. during protoplanetary irradiation, causing disorder. Th e most pristine interplanetary dust particles (IDPs) may come from comets. However, their exact provenance is unknown. IDP collection during Earth?s passage through comet Grigg-Skjellerup?s dust stream ("GSC" collectors) may increase the probability of collecting fresh IDPs from a known, cometary source. We used Raman spectroscopy to compare 21 GSC-IDPs with 15 IDPs collected at different periods, and found that the variation among GSC-IDPs is larger than among non-GSC IDPs, with the most primitive IDPs being mostly GSC-IDPs.

  15. In Ovo Sexing of Domestic Chicken Eggs by Raman Spectroscopy.

    PubMed

    Galli, Roberta; Preusse, Grit; Uckermann, Ortrud; Bartels, Thomas; Krautwald-Junghanns, Maria-Elisabeth; Koch, Edmund; Steiner, Gerald

    2016-09-01

    Male birds of egg-laying hen strains have no commercial value and are culled immediately after hatching, raising concerns for animal welfare. Existing experimental methods for in ovo sexing require taking samples and are applicable after embryos' sexual differentiation. We demonstrate that Raman spectroscopy enables contactless in ovo sex determination of the domestic chicken (Gallus gallus f. dom.) already at day 3.5 of egg incubation. A sexing accuracy of 90% was obtained by analyzing the spectra of blood circulating in the extraembryonic vessels. The measurement is damage-free and barely affects the hatching rate. Sex recognition is achieved before the onset of sensitivity. Therefore, Raman spectroscopy provides an alternative to the culling of 1-day-old male chicks in laying hen production. PMID:27512829

  16. Surface- and Tip-Enhanced Raman Spectroscopy in Catalysis.

    PubMed

    Hartman, Thomas; Wondergem, Caterina S; Kumar, Naresh; van den Berg, Albert; Weckhuysen, Bert M

    2016-04-21

    Surface- and tip-enhanced Raman spectroscopy (SERS and TERS) techniques exhibit highly localized chemical sensitivity, making them ideal for studying chemical reactions, including processes at catalytic surfaces. Catalyst structures, adsorbates, and reaction intermediates can be observed in low quantities at hot spots where electromagnetic fields are the strongest, providing ample opportunities to elucidate reaction mechanisms. Moreover, under ideal measurement conditions, it can even be used to trigger chemical reactions. However, factors such as substrate instability and insufficient signal enhancement still limit the applicability of SERS and TERS in the field of catalysis. By the use of sophisticated colloidal synthesis methods and advanced techniques, such as shell-isolated nanoparticle-enhanced Raman spectroscopy, these challenges could be overcome. PMID:27075515

  17. Detection of liquid hazardous molecules using linearly focused Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Cho, Soo Gyeong; Chung, Jin Hyuk

    2013-05-01

    In security, it is an important issue to analyze hazardous materials in sealed bottles. Particularly, prompt nondestructive checking of sealed liquid bottles in a very short time at the checkpoints of crowded malls, stadiums, or airports is of particular importance to prevent probable terrorist attack using liquid explosives. Aiming to design and fabricate a detector for liquid explosives, we have used linearly focused Raman spectroscopy to analyze liquid materials in transparent or semi-transparent bottles without opening their caps. Continuous lasers with 532 nm wavelength and 58 mW/130 mW beam energy have been used for the Raman spectroscopy. Various hazardous materials including flammable liquids and explosive materials have successfully been distinguished and identified within a couple of seconds. We believe that our technique will be one of suitable methods for fast screening of liquid materials in sealed bottles.

  18. Surface- and Tip-Enhanced Raman Spectroscopy in Catalysis

    PubMed Central

    2016-01-01

    Surface- and tip-enhanced Raman spectroscopy (SERS and TERS) techniques exhibit highly localized chemical sensitivity, making them ideal for studying chemical reactions, including processes at catalytic surfaces. Catalyst structures, adsorbates, and reaction intermediates can be observed in low quantities at hot spots where electromagnetic fields are the strongest, providing ample opportunities to elucidate reaction mechanisms. Moreover, under ideal measurement conditions, it can even be used to trigger chemical reactions. However, factors such as substrate instability and insufficient signal enhancement still limit the applicability of SERS and TERS in the field of catalysis. By the use of sophisticated colloidal synthesis methods and advanced techniques, such as shell-isolated nanoparticle-enhanced Raman spectroscopy, these challenges could be overcome. PMID:27075515

  19. Resonance Raman Spectroscopy of Armchair Single-Walled Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Haroz, Erik; Rice, William; Lu, Benjamin; Hauge, Robert; Magana, Donny; Doorn, Stephen; Nikolaev, Pasha; Arepalli, Sivaram; Kono, Junichiro

    2009-03-01

    We performed resonance Raman spectroscopy studies of metallic single-walled carbon nanotubes (SWNTs), including armchair SWNTs from (6,6) through (10,10). The measurements were carried out with excitation of 440-850 nm on aqueous ensemble samples of SWNTs enriched in metallic species. From this, we generated Raman excitation profiles (REPs) of the radial breathing mode and compare the REPs of armchairs and other metallic species. Additionally, we measured REPs of the G-band mode and observed how the Breit-Wigner-Fano line shape of the G^- peak evolves in peak position, width and intensity relative to the G^+ peak as different metallic nanotubes are excited. By combining these studies with absorption and photoluminescence excitation spectroscopy studies, we present a comprehensive examination of the optical signatures of metallic SWNTs.

  20. Optimizing the Laser-Pulse Configuration for Coherent Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Pestov, Dmitry; Murawski, Robert K.; Ariunbold, Gombojav O.; Wang, Xi; Zhi, Miaochan; Sokolov, Alexei V.; Sautenkov, Vladimir A.; Rostovtsev, Yuri V.; Dogariu, Arthur; Huang, Yu; Scully, Marlan O.

    2007-04-01

    We introduce a hybrid technique that combines the robustness of frequency-resolved coherent anti-Stokes Raman scattering (CARS) with the advantages of time-resolved CARS spectroscopy. Instantaneous coherent broadband excitation of several characteristic molecular vibrations and the subsequent probing of these vibrations by an optimally shaped time-delayed narrowband laser pulse help to suppress the nonresonant background and to retrieve the species-specific signal. We used this technique for coherent Raman spectroscopy of sodium dipicolinate powder, which is similar to calcium dipicolinate (a marker molecule for bacterial endospores, such as Bacillus subtilis and Bacillus anthracis), and we demonstrated a rapid and highly specific detection scheme that works even in the presence of multiple scattering.

  1. Optimizing the laser-pulse configuration for coherent Raman spectroscopy.

    PubMed

    Pestov, Dmitry; Murawski, Robert K; Ariunbold, Gombojav O; Wang, Xi; Zhi, Miaochan; Sokolov, Alexei V; Sautenkov, Vladimir A; Rostovtsev, Yuri V; Dogariu, Arthur; Huang, Yu; Scully, Marlan O

    2007-04-13

    We introduce a hybrid technique that combines the robustness of frequency-resolved coherent anti-Stokes Raman scattering (CARS) with the advantages of time-resolved CARS spectroscopy. Instantaneous coherent broadband excitation of several characteristic molecular vibrations and the subsequent probing of these vibrations by an optimally shaped time-delayed narrowband laser pulse help to suppress the nonresonant background and to retrieve the species-specific signal. We used this technique for coherent Raman spectroscopy of sodium dipicolinate powder, which is similar to calcium dipicolinate (a marker molecule for bacterial endospores, such as Bacillus subtilis and Bacillus anthracis), and we demonstrated a rapid and highly specific detection scheme that works even in the presence of multiple scattering. PMID:17431177

  2. Tip-enhanced Raman spectroscopy: From concepts to practical applications

    NASA Astrophysics Data System (ADS)

    Jiang, Nan; Kurouski, Dmitry; Pozzi, Eric A.; Chiang, Naihao; Hersam, Mark C.; Van Duyne, Richard P.

    2016-08-01

    Tip-enhanced Raman spectroscopy (TERS) is a powerful technique that integrates the vibrational fingerprinting of Raman spectroscopy and the sub-nanometer resolution of scanning probe microscopy (SPM). As a result, TERS is capable of obtaining chemical maps of analyzed specimens with exceptional lateral resolution. This is extremely valuable for the study of interactions between molecules and substrates, in addition to structural characterization of biological objects, such as viruses and amyloid fibrils, 2D polymeric materials, and monitoring electrochemical and photo-catalytic processes. In this mini-review, we discuss the most significant advances of TERS, including: super high resolution chemical imaging, monitoring of catalytic processes, incorporation of pulsed-excitation techniques, single-site electrochemistry, biosensing, and art conservation. We begin with a short overview of TERS, comparing it with other surface analytical techniques, followed by an overview of recent developments and future applications in TERS.

  3. Raman/FTIR spectroscopy of oil shale retort gases

    SciTech Connect

    Richardson, J H; Monaco, S B; Sanborn, R H; Hirschfeld, T B; Taylor, J R

    1982-08-01

    A Raman facility was assembled in order to aid in the evaluation of the feasibility of using Raman or FTIR spectroscopy for analyzing gas mixtures of interest in oil shale. Applications considered in oil shale research included both retort monitoring and laboratory kinetic studies. Both techniques gave limits of detection between 10 and 1000 ppM for ten representative pertinent gases. Both techniques are inferior as a general analytical technique for oil shale gas analysis in comparison with mass spectroscopy, which had detection limits between 1 and 50 ppM for the same gases. The conclusion of the feasibility study was to recommend that mass spectroscopic techniques be used for analyzing gases of interest to oil shale.

  4. Identification of active fluorescence stained bacteria by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krause, Mario; Beyer, Beatrice; Pietsch, Christian; Radt, Benno; Harz, Michaela; Rösch, Petra; Popp, Jürgen

    2008-04-01

    Microorganisms can be found everywhere e.g. in food both as useful ingredients or harmful contaminations causing food spoilage. Therefore, a fast and easy to handle analysis method is needed to detect bacteria in different kinds of samples like meat, juice or air to decide if the sample is contaminated by harmful microorganisms. Conventional identification methods in microbiology require always cultivation and therefore are time consuming. In this contribution we present an analysis approach to identify fluorescence stained bacteria on strain level by means of Raman spectroscopy. The stained bacteria are highlighted and can be localized easier against a complex sample environment e.g. in food. The use of Raman spectroscopy in combination with chemometrical methods allows the identification of single bacteria within minutes.

  5. Modulated Raman Spectroscopy for Enhanced Cancer Diagnosis at the Cellular Level

    PubMed Central

    De Luca, Anna Chiara; Dholakia, Kishan; Mazilu, Michael

    2015-01-01

    Raman spectroscopy is emerging as a promising and novel biophotonics tool for non-invasive, real-time diagnosis of tissue and cell abnormalities. However, the presence of a strong fluorescence background is a key issue that can detract from the use of Raman spectroscopy in routine clinical care. The review summarizes the state-of-the-art methods to remove the fluorescence background and explores recent achievements to address this issue obtained with modulated Raman spectroscopy. This innovative approach can be used to extract the Raman spectral component from the fluorescence background and improve the quality of the Raman signal. We describe the potential of modulated Raman spectroscopy as a rapid, inexpensive and accurate clinical tool to detect the presence of bladder cancer cells. Finally, in a broader context, we show how this approach can greatly enhance the sensitivity of integrated Raman spectroscopy and microfluidic systems, opening new prospects for portable higher throughput Raman cell sorting. PMID:26110401

  6. Detection of drugs of abuse by Raman spectroscopy.

    PubMed

    West, Matthew J; Went, Michael J

    2011-09-01

    Raman spectroscopy can provide rapid, sensitive, non-destructive analysis of a variety of drug types (e.g. amphetamines, alkaloids, designer drugs, and date rape drugs). This review concentrates on developments in the past 15 years. It considers identification and quantification of drugs of abuse in different types of forensic evidence, including bulk street drugs as well as traces found in drinks, on fibres/clothing, in fingerprints, on fingernails, on bank notes, and in body fluids. PMID:21960539

  7. Surface-enhanced Raman spectroscopy of surfactants on silver electrodes

    SciTech Connect

    Sun, Soncheng; Birke, R.L.; Lombardi, J.R. )

    1990-03-08

    Surface-enhanced Raman spectroscopy (SERS) has been used to study different kinds of surfactants (cationic, anionic, and nonionic surfactants) adsorbed on a roughened Ag electrode. Spectral assignments are made for the SERS spectrum of cetylpyridinium chloride (CPC), and it is shown that the molecule is oriented with its pyridinium ring end-on at the electrode surface at potentials positive to the point of zero charge (pzc) on Ag.

  8. Assessment of Raman Spectroscopy as a Silicone Pad Production Diagnostic

    SciTech Connect

    Saab, A P; Balazs, G B; Maxwell, R S

    2005-05-05

    Silicone pressure pads are currently deployed in the W80. The mechanical properties of these pads are largely based on the degree of crosslinking between the polymer components that comprise the raw gumstock from which they are formed. Therefore, it is desirable for purposes of both production and systematic study of these materials to have a rapid, reliable means of assaying the extent of crosslinking. The present report describes the evaluation of Raman spectroscopy in this capacity.

  9. Profiling an electrospray plume using surface-enhanced Raman spectroscopy.

    PubMed

    Davis, Douglas; Portelius, Erik; Zhu, Yu; Feigerle, Charles; Cook, Kelsey D

    2005-12-15

    We report the use of silver nanoparticles to obtain surface-enhanced Raman spectra of Crystal Violet in an electrospray plume. Surface enhancement allowed detection at low concentrations with the high specificity afforded by vibrational spectroscopy. SERS spectra were used to obtain an axial concentration profile closely matching that obtained in previous fluorescence experiments. SERS can provide more analyte structural information than has been obtainable from fluorescence studies of the plume. PMID:16351168

  10. Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.

    DOEpatents

    Alfano, Robert R.; Wang, Wubao

    2000-11-21

    A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. In accordance with the teachings of the invention, a low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic tansaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively. For example, it may also be used to diagnose diseases associated with the concentration of Raman-active constituents in urine, lymph and saliva It may be used to identify cancer in the breast, cervix, uterus, ovaries and the like by measuring the fingerprint excitation Raman spectra of these tissues. It may also be used to reveal the growing of tumors or cancers by measuring the levels of nitric oxide in tissue.

  11. Detection of propofol concentrations in blood by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wróbel, M. S.; Gnyba, M.; UrniaŻ, R.; Myllylä, T. S.; Jedrzejewska-Szczerska, M.

    2015-07-01

    In this paper we present a proof-of-concept of a Raman spectroscopy-based approach for measuring the content of propofol, a common anesthesia drug, in whole human blood, and plasma, which is intended for use during clinical procedures. This method utilizes the Raman spectroscopy as a chemically-sensitive method for qualitative detection of the presence of a drug and a quantitative determination of its concentration. A number of samples from different patients with added various concentrations of propofol IV solution were measured. This is most equivalent to a real in-vivo situation. Subsequent analysis of a set of spectra was carried out to extract qualitative and quantitative information. We conclude, that the changes in the spectra of blood with propofol, overlap with the most prominent lines of the propofol solution, especially at spectral regions: 1450 cm-1, 1250- 1260 cm-1, 1050 cm-1, 875-910 cm-1, 640 cm-1. Later, we have introduced a quantitative analysis program based on correlation matrix closest fit, and a LOO cross-validation. We have achieved 36.67% and 60% model precision when considering full spectra, or specified bands, respectively. These results prove the possibility of using Raman spectroscopy for quantitative detection of propofol concentrations in whole human blood.

  12. Raman spectroscopy for screening and diagnosis of cervical cancer.

    PubMed

    Lyng, Fiona M; Traynor, Damien; Ramos, Inês R M; Bonnier, Franck; Byrne, Hugh J

    2015-11-01

    Cervical cancer is the fourth most common cancer in women worldwide and mainly affects younger women. The mortality associated with cervical cancer can be reduced if the disease is detected at the pre-cancer stage. Current best-practice methods include cytopathology, HPV testing, and histopathology, but these methods are limited in terms of subjectivity, cost, and time. There is an unmet clinical need for new methods to aid clinicians in the early detection of cervical pre-cancer. These methods should be objective and rapid and require minimal sample preparation. Raman spectroscopy is a vibrational spectroscopic technique by which incident radiation is used to induce vibrations in the molecules of a sample and the scattered radiation may be used to characterise the sample in a rapid and non-destructive manner. Raman spectroscopy is sensitive to subtle biochemical changes occurring at the molecular level, enabling spectral variations corresponding to disease onset to be detected. Over the past 15 years, there have been numerous reports revealing the potential of Raman spectroscopy together with multivariate statistical analysis for the detection of a variety of cancers. This paper discusses the recent advances and challenges for cervical-cancer screening and diagnosis and offers some perspectives for the future. PMID:26277185

  13. Summary report of FY 1995 Raman spectroscopy technology development

    SciTech Connect

    Douglas, J.G.

    1995-11-01

    US DOE is sponsoring development of remote, fiber-optic Raman spectroscopy for rapid chemical characterization of Hanford high-level radioactive tank waste. Deployment targets for this technology are analytical hot cells and, via the Light-Duty Utility Arm and cone penetrometer, the waste tanks themselves. Perceived benefits of fiber-optic Raman spectroscopy are (1) rapid generation of tank-waste safety-related data, (2) reduced personnel exposure to highly radioactive waste, (3) reduced tank-waste sampling and analysis costs, and (4) reduced radioactive analytical waste. This document presents the results from the investigation of two dispersive, transmission-grating Raman systems and four fiber-optic Raman probe designs with non-radioactive tank waste simulants. One Raman system used a 532-nm, 400 mW, solid-state laser; the other used a 785-nm, 500 mW, solid-state diode laser. We found (1) the transmission-grating systems had better wavelength stability than previously tried Czerny-Turner-Based systems and (2) the 785-nm system`s specie detection limits in the spectral fingerprint regiion were at least as good as those for the 532-nm system. Based on these results, and the fact that some tank wastes luminesce with 514.5nm excitation, we selected the 785-nm system for hot-cell use. Of the four probes tested, three had a ``six-around-on`` fiber probe design; the fourth probe was a one-fiber-in-one-fiber-out, diffuse-relectance design. Comparison of the four probes` signal-to-noise rations, rations, transmission/collection efficiencies, and probe-silica Raman backgrounds showed that the best probe for use with Hanford-Site tank waste should (1) be filtered as close to the probe tip as possible to reduce the probe-silica Raman background and (2) have multiple collection fibers. The responses of all the probes tested showed a strong dependence on probe-sample distance, and the presence of a probe window appeared to increase the probe`s silica Raman background.

  14. Grain orientation, texture, and internal stress optically evaluated by micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Becker, M.; Scheel, H.; Christiansen, S.; Strunk, H. P.

    2007-03-01

    We present a method to experimentally determine the components of stress tensors within grains of multicrystalline materials by micro-Raman spectroscopy. This method is applied to multicrystalline silicon wafers as they are produced for solar cells. Currently, μ-Raman spectroscopy is intensively used to measure stresses in silicon wafers, structures, and devices of known crystallographic orientations. For these cases, the determination of stresses from Raman peak shifts is straightforward. In multicrystalline silicon, however, arbitrary grain orientations complicate the determination of stress tensor components, which depend on the crystallographic orientations of the particular grains. The Raman intensities depend on the polarization direction of the incident and scattered laser light and again on the crystallographic grain orientations. This intensity dependence is used to determine the crystallographic grain orientations. Once the orientation is determined, the components of the stress tensor (with respect to a fixed reference coordinate system—the sample stage), can be calculated numerically from the Raman peak shifts. As examples, we determine (i) the stress components of a nearly plane stress state around the tip of a microcrack and (ii) the stress components at a grain boundary in a multicrystalline silicon wafer.

  15. Raman spectroscopy and imaging to detect contaminants for food safety applications

    NASA Astrophysics Data System (ADS)

    Chao, Kuanglin; Qin, Jianwei; Kim, Moon S.; Peng, Yankun; Chan, Diane; Cheng, Yu-Che

    2013-05-01

    This study presents the use of Raman chemical imaging for the screening of dry milk powder for the presence of chemical contaminants and Raman spectroscopy for quantitative assessment of chemical contaminants in liquid milk. For image-based screening, melamine was mixed into dry milk at concentrations (w/w) between 0.2% and 10.0%, and images of the mixtures were analyzed by a spectral information divergence algorithm. Ammonium sulfate, dicyandiamide, and urea were each separately mixed into dry milk at concentrations (w/w) between 0.5% and 5.0%, and an algorithm based on self-modeling mixture analysis was applied to these sample images. The contaminants were successfully detected and the spatial distribution of the contaminants within the sample mixtures was visualized using these algorithms. Liquid milk mixtures were prepared with melamine at concentrations between 0.04% and 0.30%, with ammonium sulfate and with urea at concentrations between 0.1% and 10.0%, and with dicyandiamide at concentrations between 0.1% and 4.0%. Analysis of the Raman spectra from the liquid mixtures showed linear relationships between the Raman intensities and the chemical concentrations. Although further studies are necessary, Raman chemical imaging and spectroscopy show promise for use in detecting and evaluating contaminants in food ingredients.

  16. An intraoperative diagnosis of parotid gland tumors using Raman spectroscopy and support vector machine

    NASA Astrophysics Data System (ADS)

    Yan, Bing; Wen, Zhining; Li, Yi; Li, Longjiang; Xue, Lili

    2014-11-01

    The preoperative and intraoperative diagnosis of parotid gland tumors is difficult, but is important for their surgical management. In order to explore an intraoperative diagnostic method, Raman spectroscopy is applied to detect the normal parotid gland and tumors, including pleomorphic adenoma, Warthin’s tumor and mucoepidermoid carcinoma. In the 600-1800 cm-1 region of the Raman shift, there are numerous spectral differences between the parotid gland and tumors. Compared with Raman spectra of the normal parotid gland, the Raman spectra of parotid tumors show an increase of the peaks assigned to nucleic acids and proteins, but a decrease of the peaks related to lipids. Spectral differences also exist between the spectra of parotid tumors. Based on these differences, a remarkable classification and diagnosis of the parotid gland and tumors are carried out by support vector machine (SVM), with high accuracy (96.7~100%), sensitivity (93.3~100%) and specificity (96.7~100%). Raman spectroscopy combined with SVM has a great potential to aid the intraoperative diagnosis of parotid tumors and could provide an accurate and rapid diagnostic approach.

  17. Raman Spectroscopy and instrumentation for monitoring soil carbon systems.

    SciTech Connect

    Stokes, D.L.

    2003-12-08

    This work describes developments in the application of Raman scattering and surface-enhanced Raman scattering (SERS) towards the assessment/characterization of carbon in soil. In the past, the nonspecific total carbon mass content of soil samples has generally been determined through mass loss techniques and elemental analysis. However, because of the concern over CO{sub 2} buildup in the atmosphere and its possible role in the ''Greenhouse Effect,'' there is a need for better-defined models of global cycling of carbon. As a means towards this end, there is a need to know more about the structure and functionality of organic materials in soil. Raman spectroscopy may therefore prove to be an exceptional tool in soil carbon analysis. Based on vibrational transitions of irradiated molecules, it provides structural information that is often suitable for sample identification. Furthermore, Raman scattering yields very fine spectral features which offer the potential for multicomponent sample analysis with minimal or no sample pretreatment. Although the intensity of Raman scattering is generally extremely low, the surface-enhanced Raman scattering (SERS) effect can greatly enhance Raman signals (10{sup 6}-10{sup 8} range) through the adsorption of compounds on specially roughened metal surfaces. In our laboratory, we have investigated copper, gold and silver as possible substrate metals in the fabrication of SERS substrates. These substrates have included metal-coated microparticles, metal island films, and redox-roughened metal foils. We have evaluated several laser excitation sources spanning the 515-785 nm range for both Raman and SERS analysis. For this particular study, we have selected fulvic and humic acids as models for establishing the feasibility of using Raman and SERS in soil carbon analysis. Our studies thus far have demonstrated that copper substrates perform best in the SERS detection of humic and fulvic acids, particularly when coupled to electrochemical

  18. Characterization of azurite and lazurite based pigments by laser induced breakdown spectroscopy and micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bicchieri, M.; Nardone, M.; Russo, P. A.; Sodo, A.; Corsi, M.; Cristoforetti, G.; Palleschi, V.; Salvetti, A.; Tognoni, E.

    2001-06-01

    The most commonly used blue pigments in medieval manuscripts are azurite and lapis-lazuli. The first one is a copper-based pigment; the coloring compound of the latter is lazurite, a sodium silicoaluminate in a sulfur matrix. Knowledge of the chemical composition of the materials is essential for the study of illuminated manuscripts. In this paper, micro-Raman and LIBS have been used for the study of azurite and lapis-lazuli, as well as different mixtures of these pigments applied to parchment to simulate an illuminated manuscript. The results of our work show the importance of using more than one technique for a good comprehension of a manuscript. In particular, the opportunity of combining elemental information (obtained from laser induced breakdown spectroscopy) and vibrational spectroscopy information (obtained from Raman) will be fully exploited.

  19. Review on the Raman spectroscopy of different types of layered materials.

    PubMed

    Zhang, Xin; Tan, Qing-Hai; Wu, Jiang-Bin; Shi, Wei; Tan, Ping-Heng

    2016-03-28

    Two-dimensional layered materials, such as graphene and transition metal dichalcogenides (TMDs), have been under intensive investigation. The rapid progress of research on graphene and TMDs is now stimulating the exploration of different types of layered materials (LMs). Raman spectroscopy has shown its great potential in the characterization of layer numbers, interlayer coupling and layer-stacking configurations and will benefit the future explorations of other LMs. Lattice vibrations or Raman spectra of many LMs in bulk have been discussed since the 1960s. However, different results were obtained because of differences or limitations in the Raman instruments at early stages. The developments of modern Raman spectroscopy now allow us to revisit the Raman spectra of these LMs under the same experimental conditions. Moreover, to the best of our knowledge, there were limitations in detailed reviews on the Raman spectra of these different LMs. Here, we provide a review on Raman spectra of various LMs, including semiconductors, topological insulators, insulators, semi-metals and superconductors. We firstly introduce a unified method based on symmetry analysis and polarization measurements to assign the observed Raman modes and characterize the crystal structure of different types of LMs. Then, we revisit and update the positions and assignments of vibration modes by re-measuring the Raman spectra of different types of LMs and by comparing our results to those reported in previous papers. We apply the recent advances on the interlayer vibrations of graphene and TMDs to these various LMs and obtain their shear modulus. The observation of the shear modes of LMs in bulk facilitates an accurate and fast characterization of layer numbers during preparation processes in the future by a robust layer-number dependency on the frequencies of the shear modes. We also summarize the recent advances on the layer-stacking dependence on the intensities of interlayer shear vibrations

  20. Early Detection of Burn Induced Heterotopic Ossification using Transcutaneous Raman Spectroscopy

    PubMed Central

    Peterson, Jonathan R.; Okagbare, Paul I.; De La Rosa, Sara; Cilwa, Katherine E.; Perosky, Joseph E.; Eboda, Oluwatobi N.; Donneys, Alexis; Su, Grace L.; Buchman, Steven R.; Cederna, Paul S.; Wang, Stewart C.; Kozloff, Kenneth M.; Morris, Michael D; Levi, Benjamin

    2013-01-01

    Introduction Heterotopic ossification (HO), or the abnormal formation of bone in soft tissue, occurs in over 60% of major burn injuries and blast traumas. A significant need exists to improve the current diagnostic modalities for HO which are inadequate to diagnose and intervene on HO at early time-points. Raman spectroscopy has been used in previous studies to report on changes in bone composition during bone development but has not yet been applied to burn induced HO. In this study, we validate transcutaneous, in-vivo Raman spectroscopy as a methodology for early diagnosis of HO in mice following a burn injury. Methods An Achilles tenotomy model was used to study HO formation. Following tenotomy, mice were divided into burn and sham groups with exposure of 30% surface area on the dorsum to 60° water or 30° water for 18 seconds respectively. In-vivo, transcutaneous Raman spectroscopy was performed at early time points (5 days, 2 and 3 weeks) and a late time point (3 months) on both the tenotomized and non-injured leg. These same samples were then dissected down to the bone and ex-vivo Raman measurements were performed on the excised tissue. Bone formation was verified with Micro CT and histology at corresponding time-points. Results Our Raman probe allowed non-invasive, transcutaneous evaluation of heterotopic bone formation. Raman data showed significantly increased bone mineral signaling in the tenotomy compared to control leg at 5 days post injury, with the difference increasing over time whereas Micro CT did not demonstrate heterotopic bone until three weeks. Ex-vivo Raman measurements showed significant differences in the amount of HO in the burn compared to sham groups and also showed differences in the spectra of new, ectopic bone compared to pre-existing cortical bone. Conclusions Burn injury increases the likelihood of developing HO when combined with traumatic injury. In our in-vivo mouse model, Raman spectroscopy allowed for detection of HO formation

  1. Portable Sequentially Shifted Excitation Raman spectroscopy as an innovative tool for in situ chemical interrogation of painted surfaces.

    PubMed

    Conti, Claudia; Botteon, Alessandra; Bertasa, Moira; Colombo, Chiara; Realini, Marco; Sali, Diego

    2016-08-01

    We present the first validation and application of portable Sequentially Shifted Excitation (SSE) Raman spectroscopy for the survey of painted layers in art. The method enables the acquisition of shifted Raman spectra and the recovery of the spectral data through the application of a suitable reconstruction algorithm. The technique has a great potentiality in art where commonly a strong fluorescence obscures the Raman signal of the target, especially when conventional portable Raman spectrometers are used for in situ analyses. Firstly, the analytical capability of portable SSE Raman spectroscopy is critically discussed using reference materials and laboratory specimens, comparing its results with other conventional high performance laboratory instruments (benchtop FT-Raman and dispersive Raman spectrometers with an external fiber optic probe); secondly, it is applied directly in situ to study the complex polychromy of Italian prestigious terracotta sculptures of the 16(th) century. Portable SSE Raman spectroscopy represents a new investigation modality in art, expanding the portfolio of non-invasive, chemically specific analytical tools. PMID:27273377

  2. Single-cell Raman spectroscopy of irradiated tumour cells

    NASA Astrophysics Data System (ADS)

    Matthews, Quinn

    This work describes the development and application of a novel combination of single-cell Raman spectroscopy (RS), automated data processing, and principal component analysis (PCA) for investigating radiation induced biochemical responses in human tumour cells. The developed techniques are first validated for the analysis of large data sets (˜200 spectra) obtained from single cells. The effectiveness and robustness of the automated data processing methods is demonstrated, and potential pitfalls that may arise during the implementation of such methods are identified. The techniques are first applied to investigate the inherent sources of spectral variability between single cells of a human prostate tumour cell line (DU145) cultured in vitro. PCA is used to identify spectral differences that correlate with cell cycle progression and the changing confluency of a cell culture during the first 3-4 days after sub-culturing. Spectral variability arising from cell cycle progression is (i) expressed as varying intensities of protein and nucleic acid features relative to lipid features, (ii) well correlated with known biochemical changes in cells as they progress through the cell cycle, and (iii) shown to be the most significant source of inherent spectral variability between cells. This characterization provides a foundation for interpreting spectral variability in subsequent studies. The techniques are then applied to study the effects of ionizing radiation on human tumour cells. DU145 cells are cultured in vitro and irradiated to doses between 15 and 50 Gy with single fractions of 6 MV photons from a medical linear accelerator. Raman spectra are acquired from irradiated and unirradiated cells, up to 5 days post-irradiation. PCA is used to distinguish radiation induced spectral changes from inherent sources of spectral variability, such as those arising from cell cycle. Radiation induced spectral changes are found to correlate with both the irradiated dose and the

  3. Bacterial identification in real samples by means of micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rösch, Petra; Stöckel, Stephan; Meisel, Susann; Bossecker, Anja; Münchberg, Ute; Kloss, Sandra; Schumacher, Wilm; Popp, Jürgen

    2011-07-01

    Pathogen detection is essential without time delay especially for severe diseases like sepsis. Here, the survival rate is dependent on a prompt antibiosis. For sepsis three hours after the onset of shock the survival rate of the patient drops below 60 %. Unfortunately, the results from standard diagnosis methods like PCR or microbiology can normally be received after 12 or 36 h, respectively. Therefore diagnosis methods which require less cultivation or even no cultivation at all have to be established for medical diagnosis. Here, Raman spectroscopy, as a vibrational spectroscopic method, is a very sensitive and selective approach and monitors the biochemical composition of the investigated sample. Applying micro-Raman spectroscopy allows for a spatial resolution below 1 μm and is therefore in the size range of bacteria. Raman spectra of bacteria depend on the physiological status. Therefore, the databases require the inclusion of the necessary environmental parameters such as temperature, pH, nutrition, etc. Such large databases therefore require a specialized chemometric approach, since the variation between different strains is small. In this contribution we will demonstrate the capability of Raman spectroscopy to identify pathogens without cultivation even from real environmental or medical samples.

  4. Photonic-Crystal-Fiber Raman Spectroscopy for Real-Time, Gas-Composition Analysis

    SciTech Connect

    Buric, M.P.; Chen, K.P.; Falk, J.; Woodruff, S.D.

    2008-01-01

    Raman spectroscopy in a hollow-core, photonic crystal fiber is reported. The fiber is used as the sample cell and the Stokes light collector. Raman signals were observed for major species in air and natural gas.

  5. Femtosecond stimulated Raman spectroscopy of ultrafast biophysical reaction dynamics

    NASA Astrophysics Data System (ADS)

    McCamant, David William

    2004-12-01

    I have developed the technique of femtosecond stimulated Raman spectroscopy (FSRS), which enables the rapid acquisition of vibrational spectra with <100-fs time-resolution and <15-cm-1 frequency-resolution. FSRS uses three laser pulses: (1) a femtosecond visible actinic pump that initiates the photochemistry, (2) a narrow bandwidth picosecond Raman pump that provides the energy for amplification of the probe, and (3) a femtosecond continuum probe that is amplified at Raman resonances shifted from the Raman pump. FSRS has the ability to collect Raman spectra and depolarization ratios with only seconds of data averaging and negligible fluorescence interference. The capabilities of FSRS are explored through studies of the polyene beta-carotene. My initial experiments used picosecond time-resolved Stokes and anti-Stokes spontaneous resonance Raman spectroscopy to determine that vibrational relaxation in the S1 (2Ag-) electronic state is nearly complete within 2 ps and to quantify the intramolecular vibrational energy redistribution (IVR) processes in S0. FSRS studies on beta-carotene revealed that following optical excitation to S2 (1Bu +) the molecule relaxes to S1 in 160 fs where it undergoes rapid two-step IVR with 200- and 450-fs time constants. In later work, the FSRS spectrum of S2 beta-carotene was observed, which consists of three intense and broad bands at ˜1100, 1300 and 1650 cm-1 that exhibit kinetics matching the decay of the S2 near-infrared absorption. These data show that there is no additional intermediate 1B u- electronic state involved in the relaxation pathway of beta-carotene. FSRS was also used to study the photoisomerization dynamics in bacteriorhodopsin (bR). Spectra obtained during bR's excited state lifetime exhibit dispersive lineshapes at the ground-state frequencies that decay in 250 fs and are attributed to a nonlinear emission process. This relaxation is significantly faster than the decay of the stimulated emission (˜500 fs), indicating

  6. Nanofluidic channel based biosensor using surface enhanced raman spectroscopy (SERS)

    NASA Astrophysics Data System (ADS)

    Chou, I.-Hsien; Beier, Hope T.; Wang, Maio; Jing, Nan; Kameoka, Jun; Coté, Gerard L.

    2007-02-01

    The Raman scattering signature of molecules has been demonstrated to be greatly enhanced, on the order of 10 6-10 12 times, on roughened metal surfaces and clustered structures such as aggregated colloidal gold. Here we describe a method that improves reproducibility and sensitivity of the substrate for surface enhanced Raman spectroscopy (SERS) by using a nanofluidic trapping device. This nanofluidic device has a bottle neck shape composed of a microchannel leading into a nano channel that causes size-dependent trapping of nanoparticles. The analyte and Au nanoparticles, 60 nm in diameter, in aqueous solution was pumped into the channel. The nanoparticles which were larger than the narrow channel are trapped at the edge of the channel to render an enhancement of the Raman signal. We have demonstrated that the Raman scattering signal enhancement on a nanochannel-based colloidal gold cluster is able to detect 10 pM of adenine, the test analyte, without chemical modification. The efficiency and robustness of the device suggests potential for single molecule detection and multicomponent detection for biological applications and/or biotoxins.

  7. Laser Diode Raman Spectroscopy Without the Rayleigh Line.

    NASA Astrophysics Data System (ADS)

    Sabbaghzadeh, Jamshid

    1995-01-01

    The intensity of Rayleigh scattering which is typically four to ten orders of magnitude larger than rotational Raman scattering sets severe limitations on the measurements of Raman intensities close to the excitation line. In order to remove this unwanted light, it is common to use either a subtractive filter stage double spectrometer or a holographic filter. These solutions carry a high price since some parts of the pure rotational spectra of the molecule very close to the Rayleigh line will be blocked. In addition, the combination of a filter stage with the spectrograph makes the device more cumbersome and prevents Raman spectroscopy from being used in many applications, where high sensitivity such as industrial continuous emission monitoring (CEM) is required. We have succeeded to suppress the Rayleigh line with a resonant atomic vapor cell which can reduce the intensity of the Rayleigh line by many orders of magnitude. Rubidium atoms, which have a resonance line at 780.027 nm, absorb the Rayleigh light very effectively if the incident laser frequency is tuned to the absorption lines of the atoms. This technique makes it possible to measure the Raman intensities of gases only a few GHz away from the Rayleigh line without loss of intensities.

  8. Genomic DNA characterization of pork spleen by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Guzmán-Embús, D. A.; Orrego Cardozo, M.; Vargas-Hernández, C.

    2013-11-01

    In this paper, the study of Raman signal enhancement due to interaction between ZnO rods and pork spleen DNA is reported. ZnO microstructures were synthesized by the Sol-Gel method and afterward combined with porcine spleen DNA extracted in the previous stages, following standardized cell lysis, deproteinization, and precipitation processes. Raman spectroscopy was used for the characterization of structures of ZnO and ZnO-DNA complex, and the results show the respective bands of ZnO wurtzite hexagonal phase for modes E2 (M), A1(TO), E2(High), E1(LO), and 2LO. Due to the SERS effect in the spectral range from 200 to 1800 cm,-1 Raman bands caused by vibrations of the deoxyribose C-O-C binding were also observed, producing deformation of the ring as shown in the 559 cm-1 peak. The broad band at 782 cm-1, together with the complex vibration of the string 5'-COPO-C3', is over a wide band of thymine (790 cm-1) or cytosine (780 cm-1). A prominent band near 1098 cm-1 assigned to symmetric stretching vibration phosphodioxy group (PO2-) DNA backbone is most favoured in intensity by the addition of ZnO particles originated by the SERS effect. This effect suggests a possible mechanism for enhancing the Raman signal due to the electromagnetic interaction between a DNA molecule and the flat surface of the ZnO rod.

  9. Contributions of Raman spectroscopy to the understanding of bone strength

    PubMed Central

    Mandair, Gurjit S; Morris, Michael D

    2015-01-01

    Raman spectroscopy is increasingly commonly used to understand how changes in bone composition and structure influence tissue-level bone mechanical properties. The spectroscopic technique provides information on bone mineral and matrix collagen components and on the effects of various matrix proteins on bone material properties as well. The Raman spectrum of bone not only contains information on bone mineral crystallinity that is related to bone hardness but also provides information on the orientation of mineral crystallites with respect to the collagen fibril axis. Indirect information on collagen cross-links is also available and will be discussed. After a short introduction to bone Raman spectroscopic parameters and collection methodologies, advances in in vivo Raman spectroscopic measurements for animal and human subject studies will be reviewed. A discussion on the effects of aging, osteogenesis imperfecta, osteoporosis and therapeutic agents on bone composition and mechanical properties will be highlighted, including genetic mouse models in which structure–function and exercise effects are explored. Similarly, extracellular matrix proteins, proteases and transcriptional proteins implicated in the regulation of bone material properties will be reviewed. PMID:25628882

  10. Single-shot detection of bacterial endospores via coherent Raman spectroscopy

    PubMed Central

    Pestov, Dmitry; Wang, Xi; Ariunbold, Gombojav O.; Murawski, Robert K.; Sautenkov, Vladimir A.; Dogariu, Arthur; Sokolov, Alexei V.; Scully, Marlan O.

    2008-01-01

    Recent advances in coherent Raman spectroscopy hold exciting promise for many potential applications. For example, a technique, mitigating the nonresonant four-wave-mixing noise while maximizing the Raman-resonant signal, has been developed and applied to the problem of real-time detection of bacterial endospores. After a brief review of the technique essentials, we show how extensions of our earlier experimental work [Pestov D, et al. (2007) Science 316:265–268] yield single-shot identification of a small sample of Bacillus subtilis endospores (≈104 spores). The results convey the utility of the technique and its potential for “on-the-fly” detection of biohazards, such as Bacillus anthracis. The application of optimized coherent anti-Stokes Raman scattering scheme to problems requiring chemical specificity and short signal acquisition times is demonstrated. PMID:18184801

  11. Towards optical fibre based Raman spectroscopy for the detection of surgical site infection

    NASA Astrophysics Data System (ADS)

    Thompson, Alex J.; Koziej, Lukasz; Williams, Huw D.; Elson, Daniel S.; Yang, Guang-Zhong

    2016-03-01

    Surgical site infections (SSIs) are common post-surgical complications that remain significant clinical problems, as they are associated with substantial mortality and morbidity. As such, there is significant interest in the development of minimally invasive techniques that permit early detection of SSIs. To this end, we are applying a compact, clinically deployable Raman spectrometer coupled to an optical fibre probe to the study of bacteria, with the long term goal of using Raman spectroscopy to detect infection in vivo. Our system comprises a 785 nm laser diode for excitation and a commercial (Ocean Optics, Inc.) Raman spectrometer for detection. Here we discuss the design, optimisation and validation of this system, and describe our first experiences interrogating bacterial cells (Escherichia coli) in vitro.

  12. New insight into UO2F2 particulate structure by micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Stefaniak, Elżbieta A.; Darchuk, Larysa; Sapundjiev, Danislav; Kips, Ruth; Aregbe, Yetunde; Van Grieken, René

    2013-05-01

    Uranyl fluoride particles produced via hydrolysis of uranium hexafluoride have been deposited on different substrates: polished graphite disks, silver foil, stainless steel and gold-coated silicon wafer, and measured with micro-Raman spectroscopy (MRS). All three metallic substrates enhanced the Raman signal delivered by UO2F2 in comparison to graphite. The fundamental stretching of the U-O band appeared at 867 cm-1 in case of the graphite substrate, while in case of the others it was shifted to lower frequencies (down to 839 cm-1). All applied metallic substrates showed the expected effect of Raman signal enhancement; however the gold layer appeared to be most effective. Application of new substrates provides more information on the molecular structure of uranyl fluoride precipitation, which is interesting for nuclear safeguards and nuclear environmental analysis.

  13. Measurement of residual stress in a multi-layer semiconductor heterostructure by micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Qiu, Wei; Cheng, Cui-Li; Liang, Ren-Rong; Zhao, Chun-Wang; Lei, Zhen-Kun; Zhao, Yu-Cheng; Ma, Lu-Lu; Xu, Jun; Fang, Hua-Jun; Kang, Yi-Lan

    2016-07-01

    Si-based multilayer structures are widely used in current microelectronics. During their preparation, some inhomogeneous residual stress is induced, resulting in competition between interface mismatching and surface energy and even leading to structure failure. This work presents a methodological study on the measurement of residual stress in a multi-layer semiconductor heterostructure. Scanning electron microscopy (SEM), micro-Raman spectroscopy (MRS), and transmission electron microscopy (TEM) were applied to measure the geometric parameters of the multilayer structure. The relationship between the Raman spectrum and the stress/strain on the [100] and [110] crystal orientations was determined to enable surface and cross-section residual stress analyses, respectively. Based on the Raman mapping results, the distribution of residual stress along the depth of the multi-layer heterostructure was successfully obtained.

  14. Microsystem light source at 488 nm for shifted excitation resonance Raman difference spectroscopy.

    PubMed

    Maiwald, Martin; Schmidt, Heinar; Sumpf, Bernd; Güther, Reiner; Erbert, Götz; Kronfeldt, Heinz-Detlef; Tränkle, Günther

    2009-11-01

    A microsystem light source emitting at 488 nm was tested and applied as a light source for shifted excitation resonance Raman difference spectroscopy (SERRDS). A nonlinear frequency conversion using a distributed feedback (DFB) diode laser emission at 976 nm and a periodically poled lithium niobate (PPLN) waveguide crystal was realized on a micro-optical bench with a footprint of 25 mm x 5 mm. Joint temperature management via the microbench is used for wavelength tuning. Two emission lines at 487.61 nm and 487.91 nm are used for the SERRDS experiments. The Raman spectra of the test sample polystyrene demonstrate that a laser bandpass filter did not need to be implemented. Resonance Raman spectra of Tartrazine (FD&C Yellow 5, E 102) in distilled water are presented to demonstrate the suitability of this light source for SERRDS in, e.g., food safety control. PMID:19891837

  15. New insight into UO2F2 particulate structure by micro-Raman spectroscopy

    DOE PAGESBeta

    Stefaniak, Elzbieta A.; Darchuk, Larysa; Sapundjiev, Danislav; Kips, Ruth E.; Aregbe, Yetunde; Grieken, Rene Van

    2013-02-19

    Uranyl fluoride particles produced via hydrolysis of uranium hexafluoride have been deposited on different substrates: polished graphite disks, silver foil, stainless steel and gold-coated silicon wafer, and measured with micro-Raman spectroscopy (MRS). All three metallic substrates enhanced the Raman signal delivered by UO2F2 in comparison to graphite. The fundamental stretching of the U–O band appeared at 867 cm–1 in case of the graphite substrate, while in case of the others it was shifted to lower frequencies (down to 839 cm–1). All applied metallic substrates showed the expected effect of Raman signal enhancement; however the gold layer appeared to be mostmore » effective. Lastly, application of new substrates provides more information on the molecular structure of uranyl fluoride precipitation, which is interesting for nuclear safeguards and nuclear environmental analysis.« less

  16. Classification and identification of pigmented cocci bacteria relevant to the soil environment via Raman spectroscopy.

    PubMed

    Kumar, Vinay; Kampe, Bernd; Rösch, Petra; Popp, Jürgen

    2015-12-01

    A soil habitat consists of a significant number of bacteria that cannot be cultivated by conventional means, thereby posing obvious difficulties in their classification and identification. This difficulty necessitates the need for advanced techniques wherein a well-compiled biomolecular database consisting of the already cultivable bacteria can be used as a reference in an attempt to link the noncultivable bacteria to their closest phylogenetic groups. Raman spectroscopy has been successfully applied to taxonomic studies of many systems like bacteria, fungi, and plants relying on spectral differences contributed by the variation in their overall biomolecular composition. However, these spectral differences can be obscured due to Raman signatures from photosensitive microbial pigments like carotenoids that show enormous variation in signal intensity hindering taxonomic investigations. In this study, we have applied laser-induced photobleaching to expel the carotenoid signatures from pigmented cocci bacteria. Using this method, we have investigated 12 species of pigmented bacteria abundant in soil habitats belonging to three genera mainly Micrococcus, Deinococcus, and Kocuria based on their Raman spectra with the assistance of a chemometric tool known as the radial kernel support vector machine (SVM). Our results demonstrate the potential of Raman spectroscopy as a minimally invasive taxonomic tool to identify pigmented cocci soil bacteria at a single-cell level. PMID:25940486

  17. Study of antibacterial mechanism of graphene oxide using Raman spectroscopy

    PubMed Central

    Nanda, Sitansu Sekhar; Yi, Dong Kee; Kim, Kwangmeyung

    2016-01-01

    Graphene oxide (GO) is extensively proposed as an effective antibacterial agent in commercial product packaging and for various biomedical applications. However, the antibacterial mode of action of GO is yet hypothetical and unclear. Here we developed a new and sensitive fingerprint approach to study the antibacterial activity of GO and underlying mechanism, using Raman spectroscopy. Spectroscopic signatures obtained from biomolecules such as Adenine and proteins from bacterial cultures with different concentrations of GO, allowed us to probe the antibacterial activity of GO with its mechanism at the molecular level. Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as model micro-organisms for all the experiments performed. The observation of higher intensity Raman peaks from Adenine and proteins in GO treated E. coli and E. faecalis; correlated with induced death, confirmed by Scanning electron Microscopy (SEM) and Biological Atomic Force Microscopy (Bio-AFM). Our findings open the way for future investigations of the antibacterial properties of different nanomaterial/GO composites using Raman spectroscopy. PMID:27324288

  18. Raman spectroscopy study of calcium oxalate extracted from cacti stems.

    PubMed

    Frausto-Reyes, Claudio; Loza-Cornejo, Sofia; Terrazas, Teresa; Terrazas, Tania; Miranda-Beltrán, María de la Luz; Aparicio-Fernández, Xóchitl; López-Macías, Brenda M; Morales-Martínez, Sandra E; Ortiz-Morales, Martín

    2014-01-01

    To find markers that distinguish the different Cactaceae species, by using near infrared Raman spectroscopy and scanning electron microscopy, we studied the occurrence, in the stem, of solid deposits in five Cactaceae species (Coryphantha clavata, Ferocactus latispinus, Opuntia ficus-indica, O. robusta, and O. strepthacantha) collected from their natural habitats from a region of México. The deposits in the tissues usually occurred as spheroidal aggregates, druses, or prismatic crystals. From the Raman spectra, the crystals were identified either as calcium oxalate monohydrate (CaC2O4·H2O) or calcium oxalate dihydrate (CaC2O4·2H2O). Opuntia species (subfamily Opuntioideae) showed the presence of CaC2O4·H2O, and the deposition of CaC2O4·2H2O was present in C. clavata and F. latispinus (subfamily Cactoideae, Cacteae tribe). As a punctual technique, Raman spectroscopy seems to be a useful tool to identify crystal composition. In addition to allowing the analysis of crystal morphology, this spectroscopic technique can be used to identify Cactaceae species and their chemotaxonomy. PMID:25280368

  19. Raman spectroscopy of hot desert, high altitude epilithic lichens.

    PubMed

    Villar, Susana E Jorge; Edwards, Howell G M; Seaward, Mark R D

    2005-05-01

    Twenty-three highly-coloured lichen specimens belonging to the genera Candelariella, Aspicilia and Xanthoria from high altitude sites in the Atacama Desert, Chile, 2300-4500 metres, have been analysed non-destructively by Raman spectroscopy. The vibrational band assignments in the spectra of the specimens, which were still attached to their limestone or sandstone substrata, were accomplished by comparison with the chemical compositions obtained from wet chemical extraction methods. Carotenoids and chlorophyll were found in all specimens as major components and the characteristic spectral signatures of calcium oxalate monohydrate (whewellite) and dihydrate (weddellite) could be identified; chemical signatures were found for these materials even in lichen thalli growing on the non-calcareous substrata, indicating probably that the calcium was provided here from wind- or rain-borne sources. The Raman spectral biomarkers for a variety of protective biomolecules and accessory pigments such as usnic acid, calycin, pulvinic acid dilactone and rhizocarpic acid have been identified in the lichens, in broad agreement with the chemical extraction profiles. The present study indicates that some form of non-destructive taxonomic identification based on Raman spectroscopy was also possible. PMID:15852144

  20. A method for determining nutritional facts with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Moustakas, Christos; Pitris, Constantinos

    2009-07-01

    The estimation of the nutritional parameters of food products is a difficult and laborious process. Many companies spend considerable financial and other resources to frequently check the nutritional facts of their products. In addition, current methods are unsuitable for day-to-day, restaurant or home use. A new device, that would automatically estimate the nutritional facts of any edible product, could prove very useful in all of the above situations. To achieve that goal, Raman Spectroscopy was used to examine a wide variety of commonly available food products. There was minimal sample preparation, mainly homogenization and dilution. Raman spectra were collected with 785 nm excitation and 4.5 cm-1 resolution. The spectra were analyzed and solutions to linear differential equations resulted in estimates of nutritional facts. When the analysis techniques were optimized, several nutritional parameters could be estimated, such as calories, fat, protein, carbohydrates, sugars, and fiber, with an error between 2.9 % and 6.7 %. The results imply that Raman spectroscopy can be used for the estimation of the nutritional facts of food products with an error less than what is required for labeling. A device based on this technique could prove to be a very useful tool for dieticians, hospitals, food companies, health care organizations, restaurants and even home users, who want to be informed about the content of the food that they consume.

  1. Raman spectroscopy of PIN hydrogenated amorphous silicon solar cells

    NASA Astrophysics Data System (ADS)

    Keya, Kimitaka; Torigoe, Yoshihiro; Toko, Susumu; Yamashita, Daisuke; Seo, Hyunwoong; Itagaki, Naho; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Light-induced degradation of hydrogenated amorphous silicon (a-Si:H) is a key issue for enhancing competitiveness in solar cell market. A-Si:H films with a lower density of Si-H2 bonds shows higher stability. Here we identified Si-H2 bonds in PIN a-Si:H solar cells fabricated by plasma CVD using Raman spectroscopy. A-Si:H solar cell has a structure of B-doped μc-SiC:H (12.5 nm)/ non-doped a-Si:H (250nm)/ P-doped μc-Si:H (40 nm) on glass substrates (Asahi-VU). By irradiating HeNe laser light from N-layer, peaks correspond to Si-H2 bonds (2100 cm-1) and Si-H bonds (2000 cm-1) have been identified in Raman scattering spectra. The intensity ratio of Si-H2 and Si-H ISiH2/ISiH is found to correlate well to light induced degradation of the cells Therefore, Raman spectroscopy is a promising method for studying origin of light-induced degradation of PIN solar cells.

  2. Study of antibacterial mechanism of graphene oxide using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Nanda, Sitansu Sekhar; Yi, Dong Kee; Kim, Kwangmeyung

    2016-06-01

    Graphene oxide (GO) is extensively proposed as an effective antibacterial agent in commercial product packaging and for various biomedical applications. However, the antibacterial mode of action of GO is yet hypothetical and unclear. Here we developed a new and sensitive fingerprint approach to study the antibacterial activity of GO and underlying mechanism, using Raman spectroscopy. Spectroscopic signatures obtained from biomolecules such as Adenine and proteins from bacterial cultures with different concentrations of GO, allowed us to probe the antibacterial activity of GO with its mechanism at the molecular level. Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as model micro-organisms for all the experiments performed. The observation of higher intensity Raman peaks from Adenine and proteins in GO treated E. coli and E. faecalis; correlated with induced death, confirmed by Scanning electron Microscopy (SEM) and Biological Atomic Force Microscopy (Bio-AFM). Our findings open the way for future investigations of the antibacterial properties of different nanomaterial/GO composites using Raman spectroscopy.

  3. In vivo lipidomics using single-cell Raman spectroscopy

    PubMed Central

    Wu, Huawen; Volponi, Joanne V.; Oliver, Ann E.; Parikh, Atul N.; Simmons, Blake A.; Singh, Seema

    2011-01-01

    We describe a method for direct, quantitative, in vivo lipid profiling of oil-producing microalgae using single-cell laser-trapping Raman spectroscopy. This approach is demonstrated in the quantitative determination of the degree of unsaturation and transition temperatures of constituent lipids within microalgae. These properties are important markers for determining engine compatibility and performance metrics of algal biodiesel. We show that these factors can be directly measured from a single living microalgal cell held in place with an optical trap while simultaneously collecting Raman data. Cellular response to different growth conditions is monitored in real time. Our approach circumvents the need for lipid extraction and analysis that is both slow and invasive. Furthermore, this technique yields real-time chemical information in a label-free manner, thus eliminating the limitations of impermeability, toxicity, and specificity of the fluorescent probes common in currently used protocols. Although the single-cell Raman spectroscopy demonstrated here is focused on the study of the microalgal lipids with biofuel applications, the analytical capability and quantitation algorithms demonstrated are applicable to many different organisms and should prove useful for a diverse range of applications in lipidomics. PMID:21310969

  4. Study of antibacterial mechanism of graphene oxide using Raman spectroscopy.

    PubMed

    Nanda, Sitansu Sekhar; Yi, Dong Kee; Kim, Kwangmeyung

    2016-01-01

    Graphene oxide (GO) is extensively proposed as an effective antibacterial agent in commercial product packaging and for various biomedical applications. However, the antibacterial mode of action of GO is yet hypothetical and unclear. Here we developed a new and sensitive fingerprint approach to study the antibacterial activity of GO and underlying mechanism, using Raman spectroscopy. Spectroscopic signatures obtained from biomolecules such as Adenine and proteins from bacterial cultures with different concentrations of GO, allowed us to probe the antibacterial activity of GO with its mechanism at the molecular level. Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as model micro-organisms for all the experiments performed. The observation of higher intensity Raman peaks from Adenine and proteins in GO treated E. coli and E. faecalis; correlated with induced death, confirmed by Scanning electron Microscopy (SEM) and Biological Atomic Force Microscopy (Bio-AFM). Our findings open the way for future investigations of the antibacterial properties of different nanomaterial/GO composites using Raman spectroscopy. PMID:27324288

  5. Two dimensional spectroscopy of Liquids in THz-domain: THz analogue of 2D Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Okumura, K.; Tanimura, Y.

    1998-03-01

    After the initial proposal(Y. Tanimura and S. Mukamel, J. Chem. Phys. 99, 9496 (1993)), the two dimensional Raman spectroscopy in the liquid phase has been received a considerable attention. Both experimental and theoretical activity of this field has been quite high. Since we have two controllable delay times, we can obtain more information than the lower-order experiments such as OKE. The new information includes that on heterogeneous distribution in liquids. Recently, it is found that the coupling between the modes in liquids can be investigated by the technique, both experimentally and theoretically(A. Tokmakoff, M.J. Lang, D.S. Larsen, G.R. Fleming, V. Chernyak, and S. Mukamel, Phys. Rev. Lett. (in press))^,(K. Okumura and Y. Tanimura, Chem. Phys. Lett. 278, 175 (1997)) In this talk, we will emphasize that we can perform the THz analogue of the 2D Raman spectroscopy if the THz short-pulse laser becomes available, which may not be in the far future. Theoretically, we can formulate this novel THz spectroscopy on the same footing as the 2D Raman spectroscopy. We will clarify new aspects of this technique comparing with the 2D Raman spectroscopy--- the reason it worth trying the tough experiment. See

  6. Quantum Chemical Study of Raman Spectroscopy of Substituted Benzene Derivatives Adsorbed on Metal Surfaces

    NASA Astrophysics Data System (ADS)

    Wu, De-Yin; Tian, Zhong-Qun

    2011-06-01

    Surface-enhanced Raman spectroscopy (SERS) can be applied to obtain the information of molecules at the noble metal surfaces. But there are a number of difficulties to clearly correlate Raman spectra with microscopic molecular structures on metal surfaces. The main reason is that it is difficult to characterize unambiguously the metal surface structures and the influence of the binding interaction on SERS signals of the probe molecules. According to the surface selection rule of SERS, the electromagnetic enhancement will not change relative Raman intensities of vibrational modes with the same irreducible representation. Therefore, the change of the relative Raman intensities of the total symmetric modes may only originate from the chemical enhancement. In order to understand how the chemical interaction modulates the Raman intensity of individual modes, it is necessary to systematically investigate the Raman spectra of probe molecules themselves and the dependence of SERS signals on the binding interaction, adsorption sites, excitation wavelengths and metal property. Some probe molecules, including aniline, 1,4-benzenediamine, p-aminothiophenol, benzyl chlorine, and 4,4^'-bipyridine are investigated based on quantum chemical calculations. Raman spectra of these molecules and their adsorbed species were predicted and compared with experimentally measured spectra. The metal surfaces were mimicked using the metallic cluster model, where the silver or gold surfaces were replaced by silver or gold clusters, respectively. The density functional theory approach was employed to obtain the optimized structures and vibrational spectra by combining all-electron basis sets of 6-311+G** for atoms in the molecules and the poseudopotential basis set of LANL2DZ for metal atoms. The vibrational frequency shift and the relative Raman intensity are related to the adsorption configuration of the probe molecules. For all these molecules, the ring breathing mode and the C-C stretching

  7. Multidimensional resonance Raman spectroscopy by six-wave mixing in the deep UV.

    PubMed

    Molesky, Brian P; Giokas, Paul G; Guo, Zhenkun; Moran, Andrew M

    2014-09-21

    Two-dimensional (2D) resonance Raman spectroscopies hold great potential for uncovering photoinduced relaxation processes in molecules but are not yet widely applied because of technical challenges. Here, we describe a newly developed 2D resonance Raman experiment operational at the third-harmonic of a Titanium-Sapphire laser. High-sensitivity and rapid data acquisition are achieved by combining spectral interferometry with a background-free (six-pulse) laser beam geometry. The third-harmonic laser pulses are generated in a filament produced by the fundamental and second-harmonic pulses in neon gas at pressures up to 35 atm. The capabilities of the setup are demonstrated by probing ground-state wavepacket motions in triiodide. The information provided by the experiment is explored with two different representations of the signal. In one representation, Fourier transforms are carried out with respect to the two experimentally controlled delay times to obtain a 2D Raman spectrum. Further insights are derived in a second representation by dispersing the signal pulse in a spectrometer. It is shown that, as in traditional pump-probe experiments, the six-wave mixing signal spectrum encodes the wavepacket's position by way of the (time-evolving) emission frequency. Anharmonicity additionally induces dynamics in the vibrational resonance frequency. In all cases, the experimental signals are compared to model calculations based on a cumulant expansion approach. This study suggests that multi-dimensional resonance Raman spectroscopies conducted on systems with Franck-Condon active modes are fairly immune to many of the technical issues that challenge off-resonant 2D Raman spectroscopies (e.g., third-order cascades) and photon-echo experiments in the deep UV (e.g., coherence spikes). The development of higher-order nonlinear spectroscopies operational in the deep UV is motivated by studies of biological systems and elementary organic photochemistries. PMID:25240351

  8. Multidimensional resonance raman spectroscopy by six-wave mixing in the deep UV

    SciTech Connect

    Molesky, Brian P.; Giokas, Paul G.; Guo, Zhenkun; Moran, Andrew M.

    2014-09-21

    Two-dimensional (2D) resonance Raman spectroscopies hold great potential for uncovering photoinduced relaxation processes in molecules but are not yet widely applied because of technical challenges. Here, we describe a newly developed 2D resonance Raman experiment operational at the third-harmonic of a Titanium-Sapphire laser. High-sensitivity and rapid data acquisition are achieved by combining spectral interferometry with a background-free (six-pulse) laser beam geometry. The third-harmonic laser pulses are generated in a filament produced by the fundamental and second-harmonic pulses in neon gas at pressures up to 35 atm. The capabilities of the setup are demonstrated by probing ground-state wavepacket motions in triiodide. The information provided by the experiment is explored with two different representations of the signal. In one representation, Fourier transforms are carried out with respect to the two experimentally controlled delay times to obtain a 2D Raman spectrum. Further insights are derived in a second representation by dispersing the signal pulse in a spectrometer. It is shown that, as in traditional pump-probe experiments, the six-wave mixing signal spectrum encodes the wavepacket's position by way of the (time-evolving) emission frequency. Anharmonicity additionally induces dynamics in the vibrational resonance frequency. In all cases, the experimental signals are compared to model calculations based on a cumulant expansion approach. This study suggests that multi-dimensional resonance Raman spectroscopies conducted on systems with Franck-Condon active modes are fairly immune to many of the technical issues that challenge off-resonant 2D Raman spectroscopies (e.g., third-order cascades) and photon-echo experiments in the deep UV (e.g., coherence spikes). The development of higher-order nonlinear spectroscopies operational in the deep UV is motivated by studies of biological systems and elementary organic photochemistries.

  9. Identifying bacterial spores and anthrax hoax materials by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Farquharson, Stuart; Brouillette, Carl R.; Smith, Wayne

    2004-12-01

    The distribution of Bacillus anthracis spores through the US postal system in the autumn of 2001, initiated a secondary form of terror, the mailing of hoax materials. In the past three years nearly 20,000 letters containing harmless powders have been mailed, creating additional anxiety. Thus, there is a need for analyzers that can not only identify anthrax-causing spores to save lives, but also identify hoax materials to eliminate time-consuming and costly shutdowns. Recently, we established that Raman spectroscopy has the ability to identify both Bacilli endospores and hoax materials. Here we present Raman spectra of several Bacilli spores along with the dipicolinate salts, to further define the abilities of this technology to not only identify hoax materials, but also identify spores at the genus and species level.

  10. Raman spectroscopy of ripple formation in suspended graphene.

    PubMed

    Chen, Chun-Chung; Bao, Wenzhong; Theiss, Jesse; Dames, Chris; Lau, Chun Ning; Cronin, Stephen B

    2009-12-01

    Using Raman spectroscopy, we measure the optical phonon energies of suspended graphene before, during, and after thermal cycling between 300 and 700 K. After cycling, we observe large upshifts ( approximately 25 cm(-1)) of the G band frequency in the graphene on the substrate region due to compression induced by the thermal contraction of the underlying substrate, while the G band in the suspended region remains unchanged. From these large upshifts, we estimate the compression in the substrate region to be approximately 0.4%. The large mismatch in compression between the substrate and suspended regions causes a rippling of the suspended graphene, which compensates for the change in lattice constant due to the compression. The amplitude (A) and wavelength (lambda) of the ripples, as measured by atomic force microscopy, correspond to an effective change in length Deltal/l that is consistent with the compression values determined from the Raman data. PMID:19807131

  11. Stochastic Liouville equations for femtosecond stimulated Raman spectroscopy

    PubMed Central

    Agarwalla, Bijay Kumar; Ando, Hideo; Dorfman, Konstantin E.; Mukamel, Shaul

    2015-01-01

    Electron and vibrational dynamics of molecules are commonly studied by subjecting them to two interactions with a fast actinic pulse that prepares them in a nonstationary state and after a variable delay period T, probing them with a Raman process induced by a combination of a broadband and a narrowband pulse. This technique, known as femtosecond stimulated Raman spectroscopy (FSRS), can effectively probe time resolved vibrational resonances. We show how FSRS signals can be modeled and interpreted using the stochastic Liouville equations (SLE), originally developed for NMR lineshapes. The SLE provide a convenient simulation protocol that can describe complex dynamics caused by coupling to collective bath coordinates at much lower cost than a full dynamical simulation. The origin of the dispersive features that appear when there is no separation of timescales between vibrational variations and the dephasing time is clarified. PMID:25591346

  12. Rapid Classification of Ordinary Chondrites Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Fries, M.; Welzenbach, L.

    2014-01-01

    Classification of ordinary chondrites is typically done through measurements of the composition of olivine and pyroxenes. Historically, this measurement has usually been performed via electron microprobe, oil immersion or other methods which can be costly through lost sample material during thin section preparation. Raman microscopy can perform the same measurements but considerably faster and with much less sample preparation allowing for faster classification. Raman spectroscopy can facilitate more rapid classification of large amounts of chondrites such as those retrieved from North Africa and potentially Antarctica, are present in large collections, or are submitted to a curation facility by the public. With development, this approach may provide a completely automated classification method of all chondrite types.

  13. Advances in tumor diagnosis using OCT and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zakharov, V. P.; Bratchenko, I. A.; Kozlov, S. V.; Moryatov, A. A.; Kornilin, D. V.; Myakinin, O. O.; Artemyev, D. N.

    2014-05-01

    Complex investigation of malignant tumors was performed with combined optical coherence tomography (OCT) and Raman spectroscopy (RS) setup: 22 ex vivo lung tissue samples and 23 in vivo experiments with skin tumors. It was shown that combined RS-OCT unit may be used for precise tissue morphology visualization with simultaneous tumor type determination (BCC, malignant melanoma of skin tissues, adenocarcinoma and squamous cell carcinoma of lung). Fast RS phase method for skin and lung tumors identification was proposed. It is based on alteration of Raman spectral intensity in 1300-1340, 1440-1460 and 1640-1680 cm-1 bands for healthy and malignant tissue. Complex method could identify: malignant melanoma with 88.9% sensitivity and 87.8% specificity; adenocarcinoma with 100% sensitivity and 81.5% specificity; squamous cell carcinomas with 90.9% sensitivity and 77.8% specificity.

  14. [Comparison of discriminative methods of hypoglycemic drugs by Raman spectroscopy].

    PubMed

    Gao, Qun; Zhang, Zhong-Hu; Lu, Feng

    2012-12-01

    In the present paper, four kinds of cluster analysis methods were used in rapid, non-destructive discrimination of hypoglycemic tablets by the Raman spectroscopy technology. Nine kinds of hypoglycemic tablets, including 48 samples, were determined using a Raman spectrometer. The sample data were pretreated with the methods of frequency range cutting, baseline correction, smoothing and vector normalization, then were analyzed by K-means, hierachical cluster, self-organizing maps (SOM) and PCA-SOM respectively. The results demonstrated that SOM was better than K-means and hierachical cluster, and it provided the best discrimination when combined with PCA. The research offers a new approach to the rapid discrimination of different kinds of hypoglycemic tablets. PMID:23427547

  15. Raman Spectroscopy: an essential tool for future IODP expeditions

    NASA Astrophysics Data System (ADS)

    Andò, Sergio; Garzanti, Eduardo; Kulhanek, Denise K.

    2016-04-01

    The scientific drilling of oceanic sedimentary sequences plays a fundamental part in provenance studies, paleoclimate recostructions, and source-to-sink investigations (e.g., France-Lanord et al., 2015; Pandey et al., 2015). When studying oceanic deposits, Raman spectroscopy can and does represent an essential flexible tool for the multidisciplinary approach necessary to integrate the insight provided by different disciplines. This new user-friendly technique opens up an innovative avenue to study in real time the composition of detrital mineral grains of any origin, complementing traditional methods of provenance analysis (e.g., sedimentary petrography, heavy minerals; Andò and Garzanti, 2014). Raman spectra can readily reveal the chemistry of foraminiferal tests, nannofossils and other biogenic debris for the study of ecosystem evolution and paleoclimate, or the Ca/Mg ratio in biogenic or terrigenous carbonates for geological or marine biological applications and oil exploration (Borromeo et al., 2015). For the study of pelagic or turbiditic muds, which represent the bulk of the deep-marine sedimentary record, Raman spectroscopy allows us to identify silt-sized grains down to the size of a few microns with the same precision level required in quantitative provenance analysis of sand-sized sediments (Andò et al., 2011). Silt and siltstone also represent a very conspicuous part of the stratigraphic record onshore and usually preserve original mineralogical assemblages better than more permeable interbedded sand and sandstone (Blatt, 1985). Raman spectra can be obtained on sample volumes of only a few cubic microns by a confocal micro-Raman coupled with a standard polarizing light microscope using a 50× objective. The size of this apparatus can be easily placed onboard an IODP vessel to provide crucial information and quickly solve identification problems for the benefit of a wide range of scientists during future expeditions. Cited references Andò, S., Vignola

  16. Stochastic Liouville equations for femtosecond stimulated Raman spectroscopy

    SciTech Connect

    Agarwalla, Bijay Kumar; Ando, Hideo; Dorfman, Konstantin E.; Mukamel, Shaul

    2015-01-14

    Electron and vibrational dynamics of molecules are commonly studied by subjecting them to two interactions with a fast actinic pulse that prepares them in a nonstationary state and after a variable delay period T, probing them with a Raman process induced by a combination of a broadband and a narrowband pulse. This technique, known as femtosecond stimulated Raman spectroscopy (FSRS), can effectively probe time resolved vibrational resonances. We show how FSRS signals can be modeled and interpreted using the stochastic Liouville equations (SLE), originally developed for NMR lineshapes. The SLE provide a convenient simulation protocol that can describe complex dynamics caused by coupling to collective bath coordinates at much lower cost than a full dynamical simulation. The origin of the dispersive features that appear when there is no separation of timescales between vibrational variations and the dephasing time is clarified.

  17. Towards field malaria diagnosis using surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Keren; Xiong, Aoli; Yuen, Clement; Preiser, Peter; Liu, Quan

    2016-04-01

    We report three strategies of surface enhanced Raman spectroscopy (SERS) for β-hematin and hemozoin detection in malaria infected human blood, which can be potentially developed for field malaria diagnosis. In the first strategy, we used silver coated magnetic nanoparticles (Fe3O4@Ag) in combination with an external magnetic field to enhance the Raman signal of β-hematin. Then we developed two SERS methods without the requirement of magnetic field for malaria infection diagnosis. In Method 1, silver nanoparticles were synthesized separately and then mixed with lysed blood just like in traditional SERS measurements; while in Method 2, we developed an ultrasensitive SERS method by synthesizing silver nanoparticles directly inside the parasites of Plasmodium falciparum. Method 2 can be also used to detect single parasites in the ring stage.

  18. Raman spectroscopy for DNA quantification in cell nucleus.

    PubMed

    Okotrub, K A; Surovtsev, N V; Semeshin, V F; Omelyanchuk, L V

    2015-01-01

    Here we demonstrate the feasibility of a novel approach to quantify DNA in cell nuclei. This approach is based on spectroscopy analysis of Raman light scattering, and avoids the problem of nonstoichiometric binding of dyes to DNA, as it directly measures the signal from DNA. Quantitative analysis of nuclear DNA contribution to Raman spectrum could be reliably performed using intensity of a phosphate mode at 1096 cm(-1) . When compared to the known DNA standards from cells of different animals, our results matched those values at error of 10%. We therefore suggest that this approach will be useful to expand the list of DNA standards, to properly adjust the duration of hydrolysis in Feulgen staining, to assay the applicability of fuchsines for DNA quantification, as well as to measure DNA content in cells with complex hydrolysis patterns, when Feulgen densitometry is inappropriate. PMID:25355529

  19. New Material for Surface-Enhanced Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Farquharson, Stuart; Nelson, Chad; Lee, Yuan

    2004-01-01

    A chemical method of synthesis and application of coating materials that are especially suitable for surface-enhanced Raman spectroscopy (SERS) has been developed. The purpose of this development is to facilitate the utilization of the inherently high sensitivity of SERS to detect chemicals of interest (analytes) in trace amounts, without need for lengthy sample preparation. Up to now, the use of SERS has not become routine because the methods available have not been able to reproduce sampling conditions and provide quantitative measurements. In contrast, the coating materials of the present method enable analysis with minimum preparation of samples, and SERS measurements made using these materials are reproducible and reversible. Moreover, unlike in methods investigated in prior efforts to implement SERS, sampling is not restricted to such specific environments as electrolytes or specific solvents. The coating materials of this method are porous glasses, formed in sol-gel processes, that contain small particles of gold or silver metal. Materials of this type can be applied to the sample-contact surfaces of a variety of sampling and sensing devices, including glass slides, glass vials, fiber-optic probes, and glass tubes. Glass vials with their insides coated according to this method are particularly convenient for SERS to detect trace chemicals in solutions: One simply puts a sample solution containing the analyte(s) into a vial, then puts the vial into a Raman spectrometer for analysis. The chemical ingredients and the physical conditions of the sol-gel process have been selected so that the porous glass formed incorporates particles of the desired metal with size(s) to match the wavelength(s) of the SERS excitation laser in order to optimize the generation of surface plasmons. The ingredients and processing conditions have further been chosen to tailor the porosity and polarity of the glass to optimize the sample flow and the interaction between the analyte

  20. Quantitative and qualitative analysis of urine component in the toilet set using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chung, So Hyun; Park, Kwang Suk; Choi, Jong Min; Lee, Won Jin

    2004-07-01

    As a part of non-invasive and unaware measurement of physiological signal in the house of live-alone person, Raman spectroscopy was applied for urine component analysis in the toilet set. 785nm, 250-300mW output solid state diode laser and 2048 element linear silicon TE cooled CCD array were incorporated for this system. Several tests were performed for setting up Raman spectroscopy in non-constrained situation: toilet set in the house. The effect of dark current, integration time, warming up time of laser, property of probe and interference of water in the toilet were tested and controlled for appropriate measurement in this environment. The spectra were obtained immediately when the subject uses the toilet set, and they can be transmitted to the server though Bluetooth. Those spectra were pre-processed for removing or correcting the effect of undesired light scattering, sample path-length difference and baseline-effect. The preprocessed data were enhanced for more exact result of multivariate analysis. The training data was prepared for predicting unknown component and its concentration by using multivariate methods. Several kinds of multivariate methods: PCA, PCR, PLS were performed to validate what is the fittest method in this environment. Through quantitative and qualitative analysis of Raman spectroscopy"s spectra obtained in the house's toilet set, we could know the component and its concentration of urine which can be index of disease.

  1. Raman spectroscopy and imaging of whole functional cells

    NASA Astrophysics Data System (ADS)

    McNaughton, Don; Lim, Janelle; Hammer, Larissa; Langford, Steven J.; Collie, Jocelyn; Wood, Bayden R.

    2005-02-01

    With the advent of Raman spectrometers based on CCD array detectors, instruments have been coupled to optical microscopes leading to all the advantages of bright field microscopy with the added advantage of a direct chemical probe. The primary biological solvent, water, is a weak Raman scatterer and so these instruments can now be used to investigate the chemistry of living systems at spatial resolutions of 1 μm and below. We have developed techniques that allow us to study functional red blood cells and monitor the exchange of ligands and the development and chemistry of disease processes. These techniques take advantage of Aggregated Enhanced Raman Spectroscopy, which enables us to use the haem group of the haemoglobins and related haem pigments, such as the malarial pigment haemozoin, as a sensitive probe for changes in oxidation state, spin state and electronic structure. We have used the Raman microprobe to investigate the effect of drugs such as quinoline on the food vacuole of the malarial parasite in vivo. Sickle cell disease affects 1 out of 600 African American births and is caused by a mutant form (β6 glu-->val) of haemoglobin (HbS). HbS polymerizes and forms higher order aggregates under hypoxic conditions, leading to distortion and rigidity of the erythrocyte. These rigid cells can block the microvasculature resulting in tissue ischaemia, organ damage, and ultimately death. The sensitivity of the Raman technique to haem aggregation provides a tool with which we can analyse the changes that occur between normal and sickle cells.

  2. Plasmonic nanostructures for surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Jiang, Ruiqian

    In the last three decades, a large number of different plasmonic nanostructures have attracted much attention due to their unique optical properties. Those plasmonic nanostructures include nanoparticles, nanoholes and metal nanovoids. They have been widely utilized in optical devices and sensors. When the plasmonic nanostructures interact with the electromagnetic wave and their surface plasmon frequency match with the light frequency, the electrons in plasmonic nanostructures will resonate with the same oscillation as incident light. In this case, the plasmonic nanostructures can absorb light and enhance the light scattering. Therefore, the plasmonic nanostructures can be used as substrate for surface-enhanced Raman spectroscopy to enhance the Raman signal. Using plasmonic nanostructures can significantly enhance Raman scattering of molecules with very low concentrations. In this thesis, two different plasmonic nanostructures Ag dendrites and Au/Ag core-shell nanoparticles are investigated. Simple methods were used to produce these two plasmonic nanostructures. Then, their applications in surface enhanced Raman scattering have been explored. Ag dendrites were produced by galvanic replacement reaction, which was conducted using Ag nitrate aqueous solution and copper metal. Metal copper layer was deposited at the bottom side of anodic aluminum oxide (AAO) membrane. Silver wires formed inside AAO channels connected Ag nitrate on the top of AAO membrane and copper layer at the bottom side of AAO. Silver dendrites were formed on the top side of AAO. The second plasmonic nanostructure is Au/Ag core-shell nanoparticles. They were fabricated by electroless plating (galvanic replacement) reaction in a silver plating solution. First, electrochemically evolved hydrogen bubbles were used as template through electroless deposition to produce hollow Au nanoparticles. Then, the Au nanoparticles were coated with Cu shells in a Cu plating solution. In the following step, a Ag

  3. Raman spectroscopy detects melanoma and the tissue surrounding melanoma using tissue-engineered melanoma models

    PubMed Central

    Yorucu, Ceyla; Lau, Katherine; Mittar, Shweta; Green, Nicola H.; Raza, Ahtasham; Rehman, Ihtesham Ur; MacNeil, Sheila

    2016-01-01

    ABSTRACT Invasion of melanoma cells from the primary tumor involves interaction with adjacent tissues and extracellular matrix. The extent of this interaction is not fully understood. In this study Raman spectroscopy was applied to cryo-sections of established 3D models of melanoma in human skin. Principal component analysis was used to investigate differences between the tumor and normal tissue and between the peri-tumor area and the normal skin. Two human melanoma cells lines A375SM and C8161 were investigated and compared in 3D melanoma models. Changes were found in protein conformations and tryptophan configurations across the entire melanoma samples, in tyrosine orientation and in more fluid lipid packing only in tumor dense areas, and in increased glycogen content in the peri-tumor areas of melanoma. Raman spectroscopy revealed changes around the perimeter of a melanoma tumor as well as detecting differences between the tumor and the normal tissue. PMID:27158185

  4. In vitro monitoring of time and dose dependent cytotoxicity of aminated nanoparticles using Raman spectroscopy.

    PubMed

    Efeoglu, Esen; Casey, Alan; Byrne, Hugh J

    2016-09-21

    Investigation of possible adverse health effects of nanomaterials, in a rapid multi-parametric fashion, has become increasingly important, due to their increased production and potential uses in a wide range of application areas, from cosmetics to pharmaceutics. Although conventional in vitro cytotoxicological techniques provide valuable information about the particle toxicity, the importance of gaining high content information in a single assay with the analysis of multiple parameters in a non-invasive and label-free way is still one of the biggest challenges in nanotoxicology. As a vibrational spectroscopic technique, the power of Raman spectroscopy for the analysis of cells, tissues and also nanoparticle localization within cells has been shown previously. In this study, the ability of Raman spectroscopy to fingerprint the dose and time dependent cellular responses and effect of cytotoxic events on biochemical constituents of the cells is monitored. A549 human lung carcinoma cells and aminated polystyrene nanoparticles (PS-NH2) are used as a model cell line and nanoparticle, respectively. Following the determination of cellular responses in the presence of toxic PS-NH2 by using conventional cellular assays, Alamar Blue (AB) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromid (MTT), and calculation of EC50 values for both assays, Raman spectroscopy was employed at response related doses and time points. Multiple point spectra from the cytoplasm, nucleus and nucleolus of 20 cells were acquired using Raman spectroscopy for each exposure dose and timepoint. Unsupervised principle components analysis (PCA) was applied to the Raman data sets for the comparison of exposed and unexposed cells as well as different exposure doses and times. The study shows the ability of Raman spectroscopy to provide information about cellular responses at different particle concentrations and exposure times with the aid of multivariate analysis. In the chosen range of

  5. Raman and surface-enhanced Raman spectroscopy evidence for oxidation-induced decomposition of graphite

    NASA Astrophysics Data System (ADS)

    Owens, Frank J.

    2015-06-01

    It has been proposed that reduction of exfoliated graphite oxide could be a potential method for producing large quantities of graphene. Raman and surface-enhanced Raman spectroscopy are used to show that oxidation of graphite and exfoliated graphite significantly increases the defect structure of both materials. This would likely lead to a heavily defected graphene structure when oxygen is removed. To insure the observed decomposition is not due to the laser light, the effect of laser intensity on the materials was investigated. It was found that at the highest laser intensity (1.4 × 108 W/M2) there was a significant increase in defects. However, lower laser intensity was found which did not produce defects and was used in the studies of the effect of oxidation on the spectra.

  6. Rapid chemical agent identification by surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Yuan-Hsiang; Farquharson, Stuart

    2001-08-01

    Although the Chemical Weapons Convention prohibits the development, production, stockpiling, and use of chemical warfare agents (CWAs), the use of these agents persists due to their low cost, simplicity in manufacturing and ease of deployment. These attributes make these weapons especially attractive to low technology countries and terrorists. The military and the public at large require portable, fast, sensitive, and accurate analyzers to provide early warning of the use of chemical weapons. Traditional laboratory analyzers such as the combination of gas chromatography and mass spectroscopy, although sensitive and accurate, are large and require up to an hour per analysis. New, chemical specific analyzers, such as immunoassays and molecular recognition sensors, are portable, fast, and sensitive, but are plagued by false-positives (response to interferents). To overcome these limitations, we have been investigating the potential of surface-enhanced Raman spectroscopy (SERS) to identify and quantify chemical warfare agents in either the gas or liquid phase. The approach is based on the extreme sensitivity of SERS demonstrated by single molecule detection, a new SERS material that we have developed to allow reproducible and reversible measurements, and the molecular specific information provided by Raman spectroscopy. Here we present SER spectra of chemical agent simulants in both the liquid and gas phase, as well as CWA hydrolysis phase.

  7. Spectroscopic characterization of biological agents using FTIR, normal Raman and surface-enhanced Raman spectroscopies

    NASA Astrophysics Data System (ADS)

    Luna-Pineda, Tatiana; Soto-Feliciano, Kristina; De La Cruz-Montoya, Edwin; Pacheco Londoño, Leonardo C.; Ríos-Velázquez, Carlos; Hernández-Rivera, Samuel P.

    2007-04-01

    FTIR, Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) requires a minimum of sample allows fast identification of microorganisms. The use of this technique for characterizing the spectroscopic signatures of these agents and their stimulants has recently gained considerable attention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances. The techniques also show high sensitivity and selectivity and offer near real time detection duty cycles. This research focuses in laying the grounds for the spectroscopic differentiation of Staphylococcus spp., Pseudomonas spp., Bacillus spp., Salmonella spp., Enterobacter aerogenes, Proteus mirabilis, Klebsiella pneumoniae, and E. coli, together with identification of their subspecies. In order to achieve the proponed objective, protocols to handle, cultivate and analyze the strains have been developed. Spectroscopic similarities and marked differences have been found for Spontaneous or Normal Raman spectra and for SERS using silver nanoparticles have been found. The use of principal component analysis (PCA), discriminate factor analysis (DFA) and a cluster analysis were used to evaluate the efficacy of identifying potential threat bacterial from their spectra collected on single bacteria. The DFA from the bacteria Raman spectra show a little discrimination between the diverse bacterial species however the results obtained from the SERS demonstrate to be high discrimination technique. The spectroscopic study will be extended to examine the spores produced by selected strains since these are more prone to be used as Biological Warfare Agents due to their increased mobility and possibility of airborne transport. Micro infrared spectroscopy as well as fiber coupled FTIR will also be used as possible sensors of target compounds.

  8. Transcutaneous Measurement of Blood Analyte Concentration Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Barman, Ishan; Singh, Gajendra P.; Dasari, Ramachandra R.; Feld, Michael S.

    2008-11-01

    Diabetes mellitus is a chronic disorder, affecting nearly 200 million people worldwide. Acute complications, such as hypoglycemia, cardiovascular disease and retinal damage, may occur if the disease is not adequately controlled. As diabetes has no known cure, tight control of glucose levels is critical for the prevention of such complications. Given the necessity for regular monitoring of blood glucose, development of non-invasive glucose detection devices is essential to improve the quality of life in diabetic patients. The commercially available glucose sensors measure the interstitial fluid glucose by electrochemical detection. However, these sensors have severe limitations, primarily related to their invasive nature and lack of stability. This necessitates the development of a truly non-invasive glucose detection technique. NIR Raman Spectroscopy, which combines the substantial penetration depth of NIR light with the excellent chemical specificity of Raman spectroscopy, provides an excellent tool to meet the challenges involved. Additionally, it enables simultaneous determination of multiple blood analytes. Our laboratory has pioneered the use of Raman spectroscopy for blood analytes' detection in biological media. The preliminary success of our non-invasive glucose measurements both in vitro (such as in serum and blood) and in vivo has provided the foundation for the development of feasible clinical systems. However, successful application of this technology still faces a few hurdles, highlighted by the problems of tissue luminescence and selection of appropriate reference concentration. In this article we explore possible avenues to overcome these challenges so that prospective prediction accuracy of blood analytes can be brought to clinically acceptable levels.

  9. Near-infrared-excited confocal Raman spectroscopy advances in vivo diagnosis of cervical precancer

    NASA Astrophysics Data System (ADS)

    Duraipandian, Shiyamala; Zheng, Wei; Ng, Joseph; Low, Jeffrey J. H.; Ilancheran, Arunachalam; Huang, Zhiwei

    2013-06-01

    Raman spectroscopy is a unique optical technique that can probe the changes of vibrational modes of biomolecules associated with tissue premalignant transformation. This study evaluates the clinical utility of confocal Raman spectroscopy over near-infrared (NIR) autofluorescence (AF) spectroscopy and composite NIR AF/Raman spectroscopy for improving early diagnosis of cervical precancer in vivo at colposcopy. A rapid NIR Raman system coupled with a ball-lens fiber-optic confocal Raman probe was utilized for in vivo NIR AF/Raman spectral measurements of the cervix. A total of 1240 in vivo Raman spectra [normal (n=993), dysplasia (n=247)] were acquired from 84 cervical patients. Principal components analysis (PCA) and linear discriminant analysis (LDA) together with a leave-one-patient-out, cross-validation method were used to extract the diagnostic information associated with distinctive spectroscopic modalities. The diagnostic ability of confocal Raman spectroscopy was evaluated using the PCA-LDA model developed from the significant principal components (PCs) [i.e., PC4, 0.0023% PC5, 0.00095% PC8, 0.00022%, (p<0.05)], representing the primary tissue Raman features (e.g., 854, 937, 1095, 1253, 1311, 1445, and 1654 cm-1). Confocal Raman spectroscopy coupled with PCA-LDA modeling yielded the diagnostic accuracy of 84.1% (a sensitivity of 81.0% and a specificity of 87.1%) for in vivo discrimination of dysplastic cervix. The receiver operating characteristic curves further confirmed that the best classification was achieved using confocal Raman spectroscopy compared to the composite NIR AF/Raman spectroscopy or NIR AF spectroscopy alone. This study illustrates that confocal Raman spectroscopy has great potential to improve early diagnosis of cervical precancer in vivo during clinical colposcopy.

  10. Transcutaneous monitoring of steroid-induced osteoporosis with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Maher, Jason R.; Inzana, Jason; Takahata, Masahiko; Awad, Hani A.; Berger, Andrew J.

    2012-01-01

    Although glucocorticoids are among the most frequently prescribed anti-inflammatory agents used in the treatment of rheumatoid arthritis, extended exposure to this steroid hormone is the leading cause of iatrogenic osteoporosis. Recently, Raman spectroscopy has been utilized to exploit biochemical differences between osteoporotic and normal bones in order to predict fracture risk. In this presentation, we report the results of ongoing research in our laboratory towards the clinical translation of this technique. We will discuss strategies for the transcutaneous acquisition of spectra from the tibiae of mice that are of sufficient quality to generate accurate predictions of fracture risk.

  11. Raman and infrared reflection spectroscopy in black phosphorus

    NASA Astrophysics Data System (ADS)

    Sugai, S.; Shirotani, I.

    1985-03-01

    The symmetry and energies of all optically active phonon modes in black phosphorous are determined by polarized Raman scattering and infrared reflection spectroscopy at room temperature. The obtained energies are; 365 and 470 cm -1 for A g modes, 197 for B lg, 442 for B 2g, 223 and 440 for B 3g, 136 (TO) and 138 (LO) for B lu, and 468 (TO) and 470 (LO) for B 2u, respectively. The small TO-LO splitting is related to the charge transfer between phosphorus atoms induced by the atomic displacement.

  12. Raman spectroscopy for the control of the atmospheric bioindicators

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Timchenko, P. E.; Shamina, L. A.; Zherdeva, L. A.

    2015-09-01

    Experimental studies of optical parameters of different atmospheric bioindicators (arboreous and terricolous types of plants) have been performed with Raman spectroscopy. The change in the optical parameters has been explored for the objects under direct light exposure, as well as for the objects placed in the shade. The age peculiarities of the bioindicators have also been taken into consideration. It was established that the statistical variability of optical parameters for arboreous bioindicators was from 9% to 15% and for plants from 4% to 8.7%. On the basis of these results dandelion (Taraxacum) was chosen as a bioindicator of atmospheric emissions.

  13. Nanotextured surfaces for surface enhanced Raman spectroscopy and sensors

    NASA Astrophysics Data System (ADS)

    Balčytis, Armandas; JuodkazytÄ--, Jurga; Seniutinas, Gediminas; Li, Xijun; Niaura, Gediminas; Juodkazis, Saulius

    2016-03-01

    Nanotextured surfaces which have surface features spanning 10-100 nm in length and height scales are among the most promising for surface enhanced Raman scattering/spectroscopy (SERS). Randomness of the feature sizes and surface morphology of such sensors brings an added benefit of spectrally broadband action and, consequently, augmented SERS intensity. Surfaces which are most promising for high sensitivity yet cost efficient for large scale production are overviewed with black CuO, which is made by chemical oxidation of Cu foil, as a representative example. Application potential and challenges to establishing quantitative SERS measurements are outlined.

  14. Polarized Raman spectroscopy unravels the biomolecular structural changes in cervical cancer

    NASA Astrophysics Data System (ADS)

    Daniel, Amuthachelvi; Prakasarao, Aruna; Dornadula, Koteeswaran; Ganesan, Singaravelu

    2016-01-01

    Polarized Raman spectroscopy has emerged as a promising technique giving a wealth of information about the orientation and symmetry of bond vibrations in addition to the general chemical information from the conventional Raman spectroscopy. In this regard, polarized Raman Spectroscopic technique was employed to study the changes in the orientation of biomolecules in normal and cancerous conditions. This technique was compared to the conventional Raman spectroscopic technique and was found to yield additional information about the orientation of tyrosine, collagen and DNA. The statistically analyzed depolarization ratios by Linear Discriminant Analysis yielded better accuracy than the statistical results of conventional Raman spectroscopy. Thus, this study reveals that polarized Raman spectroscopy has better diagnostic potential than the conventional Raman spectroscopic technique.

  15. Plasmonic lens focused longitudinal field excitation for tip-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhang, Mingqian; Wang, Jia

    2015-04-01

    A novel tip-enhanced Raman spectroscopy setup with longitudinal field excitation generated by a plasmonic lens is investigated. A symmetry-breaking structure plasmonic lens that is expected to realize a strong longitudinal electric field focus has been designed to generate suitable excitation for enhancement in a tip antenna. The focusing performance of the plasmonic lens is theoretically simulated by the finite-difference time-domain method and experimentally verified by the detection of optical near-field distribution. A plasmonic lens assisted tip-enhanced Raman spectroscopy setup has been constructed and used to investigate specimens of carbon nanotubes. Tip-enhanced Raman spectra with distinct excitation wavelengths show similar Raman shifts but different intensities. Experimental results presented in this paper demonstrate that the Raman signal is considerably enhanced. It indicates that the novel tip-enhanced Raman spectroscopy configuration is feasible and is a promising technique for tip-enhanced Raman spectroscopy measurements and characterizations.

  16. Plasmonic lens focused longitudinal field excitation for tip-enhanced Raman spectroscopy.

    PubMed

    Zhang, Mingqian; Wang, Jia

    2015-01-01

    A novel tip-enhanced Raman spectroscopy setup with longitudinal field excitation generated by a plasmonic lens is investigated. A symmetry-breaking structure plasmonic lens that is expected to realize a strong longitudinal electric field focus has been designed to generate suitable excitation for enhancement in a tip antenna. The focusing performance of the plasmonic lens is theoretically simulated by the finite-difference time-domain method and experimentally verified by the detection of optical near-field distribution. A plasmonic lens assisted tip-enhanced Raman spectroscopy setup has been constructed and used to investigate specimens of carbon nanotubes. Tip-enhanced Raman spectra with distinct excitation wavelengths show similar Raman shifts but different intensities. Experimental results presented in this paper demonstrate that the Raman signal is considerably enhanced. It indicates that the novel tip-enhanced Raman spectroscopy configuration is feasible and is a promising technique for tip-enhanced Raman spectroscopy measurements and characterizations. PMID:25977661

  17. Development of deep subsurface Raman spectroscopy for medical diagnosis and disease monitoring.

    PubMed

    Matousek, Pavel; Stone, Nicholas

    2016-04-01

    The recently developed array of Raman spectroscopy techniques for deep subsurface analysis of biological tissues unlocks new prospects for medical diagnosis and monitoring of various biological conditions. The central pillars of these methods comprise spatially offset Raman spectroscopy (SORS) and Transmission Raman Spectroscopy facilitating penetration depths into tissue up to two orders of magnitude greater than those achievable with conventional Raman spectroscopy. This article reviews these concepts and discusses their emerging medical applications including non-invasive breast cancer diagnosis, cancer margin evaluation, bone disorder detection and glucose level determination. PMID:26455315

  18. Raman spectroscopy for the assessment of acute myeloid leukemia: a proof of concept study

    NASA Astrophysics Data System (ADS)

    Vanna, R.; Tresoldi, C.; Ronchi, P.; Lenferink, A. T. M.; Morasso, C.; Mehn, D.; Bedoni, M.; Terstappen, L. W. M. M.; Ciceri, F.; Otto, C.; Gramatica, F.

    2014-03-01

    Acute myeloid leukemia (AML) is a proliferative neoplasm, that if not properly treated can rapidly cause a fatal outcome. The diagnosis of AML is challenging and the first diagnostic step is the count of the percentage of blasts (immature cells) in bone marrow and blood sample, and their morphological characterization. This evaluation is still performed manually with a bright field light microscope. Here we report results of a study applying Raman spectroscopy for analysis of samples from two patients affected by two AML subtypes characterized by a different maturation stage in the neutrophilic lineage. Ten representative cells per sample were selected and analyzed with high-resolution confocal Raman microscopy by scanning 64x64 (4096) points in a confocal layer through the volume of the whole cell. The average spectrum of each cell was then used to obtain a highly reproducible mean fingerprint of the two different AML subtypes. We demonstrate that Raman spectroscopy efficiently distinguishes these different AML subtypes. The molecular interpretation of the substantial differences between the subtypes is related to granulocytic enzymes (e.g. myeloperoxidase and cytochrome b558), in agreement with different stages of maturation of the two considered AML subtypes . These results are promising for the development of a new, objective, automated and label-free Raman based methods for the diagnosis and first assessment of AML.

  19. Near-Real-Time Analysis of the Phenotypic Responses of Escherichia coli to 1-Butanol Exposure Using Raman Spectroscopy

    PubMed Central

    Zu, Theresah N. K.; Athamneh, Ahmad I. M.; Wallace, Robert S.; Collakova, Eva

    2014-01-01

    Raman spectroscopy was used to study the time course of phenotypic responses of Escherichia coli (DH5α) to 1-butanol exposure (1.2% [vol/vol]). Raman spectroscopy is of interest for bacterial phenotyping because it can be performed (i) in near real time, (ii) with minimal sample preparation (label-free), and (iii) with minimal spectral interference from water. Traditional off-line analytical methodologies were applied to both 1-butanol-treated and control cells to draw correlations with Raman data. Here, distinct sets of Raman bands are presented that characterize phenotypic traits of E. coli with maximized correlation to off-line measurements. In addition, the observed time course phenotypic responses of E. coli to 1.2% (vol/vol) 1-butanol exposure included the following: (i) decreased saturated fatty acids levels, (ii) retention of unsaturated fatty acids and low levels of cyclopropane fatty acids, (iii) increased membrane fluidity following the initial response of increased rigidity, and (iv) no changes in total protein content or protein-derived amino acid composition. For most phenotypic traits, correlation coefficients between Raman spectroscopy and traditional off-line analytical approaches exceeded 0.75, and major trends were captured. The results suggest that near-real-time Raman spectroscopy is suitable for approximating metabolic and physiological phenotyping of bacterial cells subjected to toxic environmental conditions. PMID:25157078

  20. Shifted excitation Raman difference spectroscopy at multiple wavelengths for in-situ meat species differentiation

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

    2012-09-01

    Two miniaturized Raman measurement heads containing microsystem diode lasers emitting at 783 and 671 nm suitable for shifted excitation Raman difference spectroscopy (SERDS) were applied for the non-invasive in situ differentiation of selected meat species. This allows using the fingerprint characteristics of Raman spectra without a disturbing fluorescence background. At 783 nm, two emission lines with a spectral shift of 0.5 nm (7 cm-1) and optical powers of up to 110 mW were realized. For 671 nm excitation, the spectral shift amounts to 0.6 nm (12 cm-1) and optical powers of up to 40 mW were obtained. In both cases, meat Raman spectra could be recorded with integration times of 10 s. The investigations were carried out using selected cuts from the most commonly consumed meat species in the US and Europe, i.e. beef, pork, chicken, and turkey. A principal components analysis of the SERDS spectra revealed a clear separation of the meat species into four distinct groups for both excitation wavelengths. This classification is based on the myoglobin content and gradual differences of protein Raman band intensities and positions. The results demonstrate the potential of SERDS as rapid and non-destructive screening method for the discrimination of selected meat species.

  1. Development of portable defocusing micro-scale spatially offset Raman spectroscopy.

    PubMed

    Realini, Marco; Botteon, Alessandra; Conti, Claudia; Colombo, Chiara; Matousek, Pavel

    2016-05-10

    We present, for the first time, portable defocusing micro-Spatially Offset Raman Spectroscopy (micro-SORS). Micro-SORS is a concept permitting the analysis of thin, highly turbid stratified layers beyond the reach of conventional Raman microscopy. The technique is applicable to the analysis of painted layers in cultural heritage (panels, canvases and mural paintings, painted statues and decorated objects in general) as well as in many other areas including polymer, biological and biomedical applications, catalytic and forensics sciences where highly turbid stratified layers are present and where invasive analysis is undesirable or impossible. So far the technique has been demonstrated only on benchtop Raman microscopes precluding the non-invasive analysis of larger samples and samples in situ. The new set-up is characterised conceptually on a range of artificially assembled two-layer systems demonstrating its benefits and performance across several application areas. These included stratified polymer sample, pharmaceutical tablet and layered paint samples. The same samples were also analysed by a high performance (non-portable) benchtop Raman microscope to provide benchmarking against our earlier research. The realisation of the vision of delivering portability to micro-SORS has a transformative potential spanning across multiple disciplines as it fully unlocks, for the first time, the non-invasive and non-destructive aspects of micro-SORS enabling it to be applied also to large and non-portable samples in situ without recourse to removing samples, or their fragments, for laboratory analysis on benchtop Raman microscopes. PMID:27055485

  2. Inflammation-related alterations of lipids after spinal cord injury revealed by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Tamosaityte, Sandra; Galli, Roberta; Uckermann, Ortrud; Sitoci-Ficici, Kerim H.; Koch, Maria; Later, Robert; Schackert, Gabriele; Koch, Edmund; Steiner, Gerald; Kirsch, Matthias

    2016-06-01

    Spinal cord injury (SCI) triggers several lipid alterations in nervous tissue. It is characterized by extensive demyelination and the inflammatory response leads to accumulation of activated microglia/macrophages, which often transform into foam cells by accumulation of lipid droplets after engulfment of the damaged myelin sheaths. Using an experimental rat model, Raman microspectroscopy was applied to retrieve the modifications of the lipid distribution following SCI. Coherent anti-Stokes Raman scattering (CARS) and endogenous two-photon fluorescence (TPEF) microscopies were used for the detection of lipid-laden inflammatory cells. The Raman mapping of CH2 deformation mode intensity at 1440 cm-1 retrieved the lipid-depleted injury core. Preserved white matter and inflammatory regions with myelin fragmentation and foam cells were localized by specifically addressing the distribution of esterified lipids, i.e., by mapping the intensity of the carbonyl Raman band at 1743 cm-1, and were in agreement with CARS/TPEF microscopy. Principal component analysis revealed that the inflammatory regions are notably rich in saturated fatty acids. Therefore, Raman spectroscopy enabled to specifically detect inflammation after SCI and myelin degradation products.

  3. Raman Spectroscopy Techniques for the Detection of Biological Samples in Suspensions and as Aerosol Particles: A Review

    NASA Astrophysics Data System (ADS)

    Félix-Rivera, Hilsamar; Hernández-Rivera, Samuel P.

    2012-03-01

    This article reviews current scientific literature focusing on Raman spectroscopy modalities that have been successfully applied to the detection of biological samples in aqueous suspensions and in aerosols. Normal Raman, surface enhanced Raman scattering, coherent anti-stokes Raman scattering, resonance Raman and UV-Raman spectropies, allow the detection of biological samples in situ in the near field and as well as in the far field at standoff distances. Applications span from fundamental studies to applied research in areas of defense and security and in monitoring of environmental pollution. A primary focus has been placed on biological samples including bacteria, pollen, virus, and biological contents in these specimens, in suspensions, and in aerosols. Several Raman spectroscopy studies have been reviewed to show how various modalities can achieve detection in these biosystems. Current data generated by our group is also included. Necessary parameters used to accomplish the detection and data analysis, which could also be used to interpret the results and to render the methodologies robust and reliable, are discussed.

  4. Distinct photoluminescence and Raman spectroscopy signatures for identifying highly crystalline WS2 monolayers produced by different growth methods

    DOE PAGESBeta

    McCreary, Amber; Berkdemir, Ayse; Wang, Junjie; Nguyen, Minh An; Elías, Ana Laura; Perea-López, Néstor; Fujisawa, Kazunori; Kabius, Bernd; Carozo, Victor; Cullen, David A.; et al

    2016-03-08

    We report that transition metal dichalcogenides (TMDs) such as WS2 show exciting promise in electronic and optoelectronic applications. Significant variations in the transport, Raman, and photoluminescence (PL) can be found in the literature, yet it is rarely addressed why this is. In this report, Raman and PL of monolayered WS2 produced via different methods are studied and distinct features that indicate the degree of crystallinity of the material are observed. While the intensity of the LA(M) Raman mode is found to be a useful indicator to assess the crystallinity, PL is drastically more sensitive to the quality of the materialmore » than Raman spectroscopy. We also show that even exfoliated crystals, which are usually regarded as the most pristine material, can contain large amounts of defects that would not be apparent without Raman and PL measurements. Ultimately, these findings can be applied to the understanding of other two-dimensional heterostructured systems.« less

  5. Tackling field-portable Raman spectroscopy of real world samples

    NASA Astrophysics Data System (ADS)

    Shand, Neil C.

    2008-10-01

    A major challenge confronting first responders, customs authorities and other security-related organisations is the accurate, rapid, and safe identification of potentially hazardous chemicals outside a laboratory environment. Currently, a range of hand portable Raman equipment is commercially available that is low cost and increasingly more sophisticated. These systems are generally based on the 785nm Stokes shifted Raman technique with many using dispersive grating spectrometers. This technique offers a broad range of capabilities including the ability to analyse illicit drugs, explosives, chemical weapons and pre-cursors but still has some fundamental constraints. 'Real world' samples, such as those found at a crime scene, will often not be presented in the most accessible manner. Simple issues such as glass fluorescence can make an otherwise tractable sample impossible to analyse in-situ. A new generation of portable Raman equipment is currently being developed to address these issues. Consideration is given to the use of longer wavelength for fluorescence reduction. Alternative optical designs are being tested to compensate for the signal reduction incurred by moving to longer wavelengths. Furthermore, the use of anti-Stokes spectroscopy is being considered as well as investigating the robustness and portability of traditional Fourier Transform interferometer designs along with future advances in detector technology and ultra small spectrometers.

  6. Discrimination of liver malignancies with 1064 nm dispersive Raman spectroscopy.

    PubMed

    Pence, Isaac J; Patil, Chetan A; Lieber, Chad A; Mahadevan-Jansen, Anita

    2015-08-01

    Raman spectroscopy has been widely demonstrated for tissue characterization and disease discrimination, however current implementations with either 785 or 830 nm near-infrared (NIR) excitation have been ineffectual in tissues with intense autofluorescence such as the liver. Here we report the use of a dispersive 1064 nm Raman system using a low-noise Indium-Gallium-Arsenide (InGaAs) array to discriminate highly autofluorescent bulk tissue ex vivo specimens from healthy liver, adenocarcinoma, and hepatocellular carcinoma (N = 5 per group). The resulting spectra have been combined with a multivariate discrimination algorithm, sparse multinomial logistic regression (SMLR), to predict class membership of healthy and diseased tissues, and spectral bands selected for robust classification have been extracted. A quantitative metric called feature importance is defined based on classification outputs and is used to guide the association of spectral features with biological indicators of healthy and diseased liver tissue. Spectral bands with high feature importance for healthy and liver tumor specimens include retinol, heme, biliverdin, or quinones (1595 cm(-1)); lactic acid (838 cm(-1)); collagen (873 cm(-1)); and nucleic acids (1485 cm(-1)). Classification performance in both binary (normal versus tumor, 100% sensitivity and 89% specificity) and three-group cases (classification accuracy: normal 89%, adenocarcinoma 74%, hepatocellular carcinoma 64%) indicates the potential for accurately separating healthy and cancerous tissues and suggests implications for utilizing Raman techniques during surgical guidance in liver resection. PMID:26309739

  7. Characterization of decavanadate and decaniobate solutions by Raman spectroscopy.

    PubMed

    Aureliano, Manuel; Ohlin, C André; Vieira, Michele O; Marques, M Paula M; Casey, William H; Batista de Carvalho, Luís A E

    2016-04-25

    The decaniobate ion, (Nb10 = [Nb10O28](6-)) being isoelectronic and isostructural with the decavanadate ion (V10 = [V10O28](6-)), but chemically and electrochemically more inert, has been useful in advancing the understanding of V10 toxicology and pharmacological activities. In the present study, the solution chemistry of Nb10 and V10 between pH 4 and 12 is studied by Raman spectroscopy. The Raman spectra of V10 show that this vanadate species dominates up to pH 6.45 whereas it remains detectable until pH 8.59, which is an important range for biochemistry. Similarly, Nb10 is present between pH 5.49 and 9.90 and this species remains detectable in solution up to pH 10.80. V10 dissociates at most pH values into smaller tetrahedral vanadate oligomers such as V1 and V2, whereas Nb10 dissociates into Nb6 under mildly (10 > pH > 7.6) or highly alkaline conditions. Solutions of V10 and Nb10 are both kinetically stable under basic pH conditions for at least two weeks and at moderate temperature. The Raman method provides a means of establishing speciation in the difficult niobate system and these findings have important consequences for toxicology activities and pharmacological applications of vanadate and niobate polyoxometalates. PMID:27031764

  8. Discrimination of liver malignancies with 1064 nm dispersive Raman spectroscopy

    PubMed Central

    Pence, Isaac J.; Patil, Chetan A.; Lieber, Chad A.; Mahadevan-Jansen, Anita

    2015-01-01

    Raman spectroscopy has been widely demonstrated for tissue characterization and disease discrimination, however current implementations with either 785 or 830 nm near-infrared (NIR) excitation have been ineffectual in tissues with intense autofluorescence such as the liver. Here we report the use of a dispersive 1064 nm Raman system using a low-noise Indium-Gallium-Arsenide (InGaAs) array to discriminate highly autofluorescent bulk tissue ex vivo specimens from healthy liver, adenocarcinoma, and hepatocellular carcinoma (N = 5 per group). The resulting spectra have been combined with a multivariate discrimination algorithm, sparse multinomial logistic regression (SMLR), to predict class membership of healthy and diseased tissues, and spectral bands selected for robust classification have been extracted. A quantitative metric called feature importance is defined based on classification outputs and is used to guide the association of spectral features with biological indicators of healthy and diseased liver tissue. Spectral bands with high feature importance for healthy and liver tumor specimens include retinol, heme, biliverdin, or quinones (1595 cm−1); lactic acid (838 cm−1); collagen (873 cm−1); and nucleic acids (1485 cm−1). Classification performance in both binary (normal versus tumor, 100% sensitivity and 89% specificity) and three-group cases (classification accuracy: normal 89%, adenocarcinoma 74%, hepatocellular carcinoma 64%) indicates the potential for accurately separating healthy and cancerous tissues and suggests implications for utilizing Raman techniques during surgical guidance in liver resection. PMID:26309739

  9. Surface-Sensitive Raman Spectroscopy of Collagen I Fibrils

    PubMed Central

    Gullekson, Corinne; Lucas, Leanne; Hewitt, Kevin; Kreplak, Laurent

    2011-01-01

    Collagen fibrils are the main constituent of the extracellular matrix surrounding eukaryotic cells. Although the assembly and structure of collagen fibrils is well characterized, very little appears to be known about one of the key determinants of their biological function—namely, the physico-chemical properties of their surface. One way to obtain surface-sensitive structural and chemical data is to take advantage of the near-field nature of surface- and tip-enhanced Raman spectroscopy. Using Ag and Au nanoparticles bound to Collagen type-I fibrils, as well as tips coated with a thin layer of Ag, we obtained Raman spectra characteristic to the first layer of collagen molecules at the surface of the fibrils. The most frequent Raman peaks were attributed to aromatic residues such as phenylalanine and tyrosine. In several instances, we also observed Amide I bands with a full width at half-maximum of 10–30 cm−1. The assignment of these Amide I band positions suggests the presence of 310-helices as well as α- and β-sheets at the fibril's surface. PMID:21463598

  10. Probing Spin Excitations Using Magneto-Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Thirunavukkuarasu, K.; Lu, Z.; Simpson, J.; Walker, A.; Sears, J.; Kim, Y.-J.; Burch, K.; Smirnov, D.

    The presence of a 2D quantum spin liquid state was recently suggested for the spin-orbit coupled Mott insulator α-RuCl3 with a honeycomb lattice.[Phys. Rev. 90, 041112 (2014)] Optical spectroscopy, Raman scattering, specific heat as well as magnetic susceptibility measurements on α-RuCl3 identified elementary excitations due to electronic correlations and spin-orbit coupling.[arXiv:1503.07593, Phys. Rev. Letters 114, 147201 (2015), and Phys. Rev. 91, 144420 (2015)] These observations appear to be consistent with theoretical expectations for Heisenberg-Kitaev model for QSL.[Phys. Rev. 91, 241110 (2015)] The underlying mechanism for the unconventional magnetism in α-RuCl3 was further investigated by probing the effect of external magnetic field on the Raman spectroscopic signatures. Raman scattering experiments were performed at temperatures down to 5 K and magnetic fields up to 10 T. The intensity of strongest A1g phonon was found to decrease with increasing magnetic field strength suggesting the presence of strong magnetic interactions. The experimental observations and its implications will be presented. Current Affiliation: Florida A and M University.

  11. Water monitoring by optofluidic Raman spectroscopy for in situ applications.

    PubMed

    Persichetti, Gianluca; Bernini, Romeo

    2016-08-01

    The feasibility of water monitoring by Raman spectroscopy with a portable optofluidic system for in-situ applications has been successfully demonstrated. In the proposed approach, the sample under analysis is injected into a capillary nozzle in order to produce a liquid jet that acts as an optical waveguide. This jet waveguide provides an effective strategy to excite and collect the Raman signals arising from water contaminants due to the high refractive index difference between air and water. The proposed approach avoids any necessity of liquid container or flow cell and removes any background signal coming from the sample container commonly affects Raman measurements. Furthermore, this absence is a significant advantage for in situ measurements where fouling problems can be relevant and cleaning procedures are troublesome. The extreme simplicity and efficiency of the optical scheme adopted in our approach result in highly sensitive and rapid measurements that have been performed on different representative water pollutants. The experimental results demonstrate the high potentiality of our device in water quality monitoring and analysis. In particular, nitrate and sulfate are detected below the maximum contamination level allowed for drinking water, whereas a limit of detection of 40mg/l has been found for benzene. PMID:27216667

  12. Identification of microbial pigments in evaporitic matrices using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Vítek, Petr; Jehlička, Jan; Edwards, Howell G. M.; Wierzchos, Jacek

    2010-05-01

    An evaporitic environment is considered as one of the possible habitats for life on Mars. From terrestrial geological scenarios we know that microorganisms inhabiting such an extreme environment (halophiles) are rich in protective pigments, depending on the metabolic pathways and specific adaptation to the harsh environmental conditions. Carotenoids typically occur within the cells of halophiles (bacteria, archaea as well as eukaryotic algae) in large amounts as part of their photosystem and protective adaptation to high doses of UV radiation that are typical for most recent evaporitic environments. Chlorophyll occurs in halophilic cyanobacteria together with carotenoids and possibly other pigments which are synthetised in response to the high UV radiation insolation. Here we present the results of Raman spectroscopic investigations of a) beta-carotene in experimentally prepared mixtures with halite, gypsum and epsomite; and b) cyanobacterial colonies inhabiting real halite and gypsum matrices in the Atacama Desert. Our results demonstrate the possibility of detection of beta-carotene - a typical carotenoid - in relatively low concentrations within the evaporitic powdered mixtures; the lowest concentration of carotenoid signal detected was 0,1 mg kg-1, which represents 100 ppb. Raman spectroscopic analyses of natural specimens (endolithic cyanobacteria) from the Atacama desert revealed the presence of scytonemin, an extremely efficient UV protective pigment, carotenoids of various types and chlorophyll. The detection potential as well as limitations of Raman spectroscopy as a part of a payload within future robotic space missions focused on the search for life on Mars is discussed.

  13. In vivo Raman spectroscopy for oral cancers diagnosis

    NASA Astrophysics Data System (ADS)

    Singh, S. P.; Deshmukh, Atul; Chaturvedi, Pankaj; Krishna, C. Murali

    2012-01-01

    Oral squamous cell carcinoma is sixth among the major malignancies worldwide. Tobacco habits are known as major causative factor in tumor carcinogenesis in oral cancer. Optical spectroscopy methods, including Raman, are being actively pursued as alternative/adjunct for cancer diagnosis. Earlier studies have demonstrated the feasibility of classifying normal, premalignant and malignant oral ex-vivo tissues. In the present study we have recorded in vivo spectra from contralateral normal and diseased sites of 50 subjects with pathologically confirmed lesions of buccal mucosa using fiber-optic-probe-coupled HE-785 Raman spectrometer. Spectra were recorded on similar points as per teeth positions with an average acquisition time of 8 seconds. A total of 215 and 225 spectra from normal and tumor sites, respectively, were recorded. Finger print region (1200-1800 cm-1) was utilized for classification using LDA. Standard-model was developed using 125 normal and 139 tumor spectra from 27 subjects. Two separate clusters with an efficiency of ~95% were obtained. Cross-validation with leave-one-out yielded ~90% efficiency. Remaining 90 normal and 86 tumor spectra were used as test data and predication efficiency of model was evaluated. Findings of the study indicate that Raman spectroscopic methods in combination with appropriate multivariate tool can be used for objective, noninvasive and rapid diagnosis.

  14. A novel extremophile strategy studied by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.

    2007-12-01

    A case is made for the classification of the colonisation by Dirina massiliensis forma sorediata of pigments on ancient wall-paintings as extremophilic behaviour. The lichen encrustations studied using FT-Raman spectroscopy have yielded important molecular information which has assisted in the identification of the survival strategy of the organism in the presence of significant levels of heavy metal toxins. The production of a carotenoid, probably astaxanthin, at the surface of the lichen thalli is identified from its characteristic biomolecular signatures in the Raman spectrum, whereas the presence of calcium oxalate dihydrate (weddellite) has been identified at both the upper and lower surfaces of the thalli and in core samples taken from depths of up to 10 mm through the encrustation into the rock substrate. The latter observation explains the significant disintegrative biodeteriorative effect of the colonisation upon the integrity of the wall-paintings and can be used to direct conservatorial and preservation efforts of the art work. A surprising result proved to be the absence of Raman spectroscopic evidence for the complexation of the metal pigments by the oxalic acid produced by the metabolic action of the organisms, unlike several cases that have been reported in the literature.

  15. Detection and quantitative analysis of chemical species in Hanford tank materials using Raman spectroscopy technology: FY94, January 1, 1994--March 31, 1995

    SciTech Connect

    Vickers, T.J.; Mann, C.

    1995-09-12

    This report provides a summary of work completed in FY-94 by FSU to develop and investigate the feasibility of using Raman spectroscopy with Hanford tank waste materials. Raman performance impacts from sample morphology, including the effects of absorption, particle size, density, color and refractive index, are discussed. An algorithm for relative species concentration measurement from Raman data is presented. An Algorithm for applying Raman to tank waste core screening is presented and discussed. A library of absorption and Raman spectra are presented that support this work.

  16. Correlation spectroscopy applied to glycerol polyester spectra

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The recent development of glycerol polyesters for use as controlled release matrix materials in the nutraceuticals and pharmaceuticals industries presented a unique opportunity to apply correlation spectroscopy. In a typical formulation the glycerol is reacted with a polyfunctional acid such as citr...

  17. Adiabatic Tip-Plasmon Focusing for Nano-Raman Spectroscopy

    SciTech Connect

    Berweger, Samuel; Atkin, Joanna M.; Olmon, Robert L.; Raschke, Markus Bernd

    2010-12-16

    True nanoscale optical spectroscopy requires the efficient delivery of light for a spatially nanoconfined excitation. We utilize adiabatic plasmon focusing to concentrate an optical field into the apex of a scanning probe tip of {approx}10 nm in radius. The conical tips with the ability for two-stage optical mode matching of the surface plasmon polariton (SPP) grating-coupling and the adiabatic propagating SPP conversion into a localized SPP at the tip apex represent a special optical antenna concept for far-field transduction into nanoscale excitation. The resulting high nanofocusing efficiency and the spatial separation of the plasmonic grating coupling element on the tip shaft from the near-field apex probe region allows for true background-free nanospectroscopy. As an application, we demonstrate tip-enhanced Raman spectroscopy (TERS) of surface molecules with enhanced contrast and its extension into the near-IR with 800 nm excitation.

  18. Characterization of Phyllosilicates by LIBS and Laser Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, A.; Sobron, P.

    2011-12-01

    NIR spectral signatures of phyllosilicates were recognized on Mars with wide distributions from orbit by OMEGA (on Mars Express orbiter) and CRISM (on Mars Reconnaissance Orbiter) observations. On the ground, geochemical and spectral features related to phyllosilicates were identified in rocks at two locations on Columbia Hill at Gusev crater using the data obtained by the Mars Exploration Rover (MER) Spirit. Furthermore, Opportunity rover is currently approaching the Cap of York at Endeavour crater on Meridiani Planum, where the signatures of phyllosilicates (and hydrous sulfates) were seen by CRISM. Laser-Induced Breakdown spectroscopy (LIBS) and Laser Raman spectroscopy will be used for the first time in rover missions in ChemCam on the NASA-MSL (Mars Science Laboratory) and in RLS on the ESA-ExoMars, respectively. As demonstrated by our previous studies, they are very powerful tools for characterizing the geochemistry and mineralogy aspects of the secondary minerals from aqueous alterations, especially hydrous sulfates. This study investigates the potential of LIBS and Raman spectroscopy for identifying and characterizing a variety of phyllosilicates, especially clays. Clay standards from the Clay Mineral Society were used. The LIBS measurements were made in a Planetary Environment and Analysis Chamber (PEACh) under Mars atmospheric pressure and composition, using 1064 nm as the excitation laser wavelength, same as ChemCam. The Raman measurements were made in ordinary laboratory environment using 532 nm as the excitation wavelength, same as RLS. The LIBS data were processed using custom automated software. We performed quantitative analysis of the spectra in order to evaluate the effectiveness of our method in: (a) discriminating between phyllosilicates and other silicates; (b) classifying different types of phyllosilicates (i.e., serpentine, chlorites, clays); and (c) correlating the LIBS-derived elemental abundances with the real chemical compositions of

  19. Use of Raman spectroscopy and chemometrics to distinguish blue ballpoint pen inks.

    PubMed

    de Souza Lins Borba, Flávia; Honorato, Ricardo Saldanha; de Juan, Anna

    2015-04-01

    The objective of this work is assessing whether the combination of Raman spectroscopy and chemometric tools is appropriate to differentiate blue ballpoint pen inks. Fourteen commercial blue ballpoint pen inks from different brands and models were studied and Raman spectra were obtained on ink lines written on A4 sulfite paper. First, a study of the best Raman configurations, in terms of laser intensity used and acquisition mode, was carried out to ensure sufficient spectroscopic quality without damaging the sample. Chemometric methods were applied first to improve the definition of spectral bands and to suppress fluorescence contributions from the signal. Once the spectra were suitably preprocessed, principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied to explore whether the different inks could be distinguished from their Raman spectra. Almost all inks could be gradually differentiated, through successive PCA analyses or looking at the different levels of the dendrogram structure provided by HCA. From these exploratory results, a tree structure was constructed based on PCA and HCA results in order to reflect the degree of similarity among ink classes. This tree structure was used as the basis to develop hierarchical classification models based on partial least squares-discriminant analysis (PLS-DA). Correct classification of inks was achieved by these PLS-DA models built and the most important regions to identify the ink classes were detected using the variable importance in projection plots (VIPs). The combination of Raman spectroscopy and chemometrics has been proven to be a promising fast non-destructive tool to differentiate among very similar ink types in documents. PMID:25679985

  20. Machine learning methods for quantitative analysis of Raman spectroscopy data

    NASA Astrophysics Data System (ADS)

    Madden, Michael G.; Ryder, Alan G.

    2003-03-01

    The automated identification and quantification of illicit materials using Raman spectroscopy is of significant importance for law enforcement agencies. This paper explores the use of Machine Learning (ML) methods in comparison with standard statistical regression techniques for developing automated identification methods. In this work, the ML task is broken into two sub-tasks, data reduction and prediction. In well-conditioned data, the number of samples should be much larger than the number of attributes per sample, to limit the degrees of freedom in predictive models. In this spectroscopy data, the opposite is normally true. Predictive models based on such data have a high number of degrees of freedom, which increases the risk of models over-fitting to the sample data and having poor predictive power. In the work described here, an approach to data reduction based on Genetic Algorithms is described. For the prediction sub-task, the objective is to estimate the concentration of a component in a mixture, based on its Raman spectrum and the known concentrations of previously seen mixtures. Here, Neural Networks and k-Nearest Neighbours are used for prediction. Preliminary results are presented for the problem of estimating the concentration of cocaine in solid mixtures, and compared with previously published results in which statistical analysis of the same dataset was performed. Finally, this paper demonstrates how more accurate results may be achieved by using an ensemble of prediction techniques.

  1. Raman Spectroscopy of Poly-Urea Formaldehyde Microcapsules

    NASA Astrophysics Data System (ADS)

    Espino, Omar; Chipara, Dorina; Chipara, Mircea; Martinez, Melissa

    2015-03-01

    The objective of this research project was to add self-healing capabilities to polymeric nanocomposites. We used the ``classical'' method to obtain self-healing polymers with the addition of TiO2 nanoparticles in the self-healing system. Self-healing polymers are obtained by dispersion of first generation Grubbs catalysts and microcapsules filled with monomers (typically DCPD). These kind of ``smart materials'' are able to survive to high mechanical stress via the ignition of the so called ``autonomous self-healing mechanism'' which is actually a ring opening methatesis polymerization (ROMP) reaction triggered by mechanical stresses in excess over a threshold limit through the rupture of microcapsules and the release of the monomeric content. As a preliminary step for adding self-healing capabilities in nanocomposites, the synthesis of microcapsules filled with dicyclopentadiene (DCPD) is vital for the addition of self-healing capabilities to polymeric matrices. We synthesized polyurea-formaldehyde (PUF) microcapsules filled with monomer (DCPD) using the in-situ polymerization. The synthesis was monitored by Raman spectroscopy, optical microscopy, and pH measurements that has been extensively used as a non-invasive techniques in the characterization of polymers and monitoring of organic reactions. The goal of this research was to assess the formation of the microcapsules during synthesis and the presence of the DCPD in the microcapsules. Samples were taken during the synthesis every 30 minutes and analyzed by Raman spectroscopy, and optical microscopy keeping a control over the pH of the solution.

  2. Femtosecond laser induced nanostructuring for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Messaoudi, H.; Das, S. K.; Lange, J.; Heinrich, F.; Schrader, S.; Frohme, M.; Grunwald, R.

    2014-03-01

    The formation of periodical nanostructures with femtosecond laser pulses was used to create highly efficient substrates for surface-enhanced Raman spectroscopy (SERS). We report about the structuring of silver and copper substrates and their application to the SERS of DNA (herring sperm) and protein molecules (egg albumen). The maximum enhancement factors were found on Ag substrates processed with the second harmonic generation (SHG) of a 1-kHz Ti:sapphire laser and structure periods near the SHG wavelength. In the case of copper, however, the highest enhancement was obtained with long-period ripples induced with at fundamental wavelength. This is explained by an additional significant influence of nanoparticles on the surface. Nanostructured areas in the range of 1.25 mm2 were obtained in 10 s. The surfaces were characterized by scanning electron microscopy, Fast Fourier Transform and Raman spectroscopy. Moreover, the role of the chemical modification of the metal structures is addressed. Thin oxide layers resulting from working in atmosphere which improve the biocompatibility were indicated by vibration spectra. It is expected that the detailed study of the mechanisms of laser-induced nanostructure formation will stimulate further applications of functionalized surfaces like photocatalysis, selective chemistry and nano-biology.

  3. Optical trapping and Raman spectroscopy of solid particles.

    PubMed

    Rkiouak, L; Tang, M J; Camp, J C J; McGregor, J; Watson, I M; Cox, R A; Kalberer, M; Ward, A D; Pope, F D

    2014-06-21

    The heterogeneous interactions of gas molecules on solid particles are crucial in many areas of science, engineering and technology. Such interactions play a critical role in atmospheric chemistry and in heterogeneous catalysis, a key technology in the energy and chemical industries. Investigating heterogeneous interactions upon single levitated particles can provide significant insight into these important processes. Various methodologies exist for levitating micron sized particles including: optical, electrical and acoustic techniques. Prior to this study, the optical levitation of solid micron scale particles has proved difficult to achieve over timescales relevant to the above applications. In this work, a new vertically configured counter propagating dual beam optical trap was optimized to levitate a range of solid particles in air. Silica (SiO2), α-alumina (Al2O3), titania (TiO2) and polystyrene were stably trapped with a high trapping efficiency (Q = 0.42). The longest stable trapping experiment was conducted continuously for 24 hours, and there are no obvious constraints on trapping time beyond this period. Therefore, the methodology described in this paper should be of major benefit to various research communities. The strength of the new technique is demonstrated by the simultaneous levitation and spectroscopic interrogation of silica particles by Raman spectroscopy. In particular, the adsorption of water upon silica was investigated under controlled relative humidity environments. Furthermore, the collision and coagulation behaviour of silica particles with microdroplets of sulphuric acid was followed using both optical imaging and Raman spectroscopy. PMID:24803083

  4. Density functional theory and Raman spectroscopy applied to structure and vibrational mode analysis of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloro- benzimidazolocarbocyanine iodide and its aggregate.

    PubMed

    Aydin, Metin; Dede, Özge; Akins, Daniel L

    2011-02-14

    We have measured electronic and Raman scattering spectra of 1,1',3,3'-tetraethyl-5,5',6,6'-tetrachloro-benzimidazolocarbocyanine iodide (TTBC) in various environments, and we have calculated the ground state geometric and spectroscopic properties of the TTBC cation in the gas and solution phases (e.g., bond distances, bond angles, charge distributions, and Raman vibrational frequencies) using density functional theory. Our structure calculations have shown that the ground state equilibrium structure of a cis-conformer lies ∼200 cm(-1) above that of a trans-conformer and both conformers have C(2) symmetry. Calculated electronic transitions indicate that the difference between the first transitions of the two conformers is about 130 cm(-1). Raman spectral assignments of monomeric- and aggregated-TTBC cations have been aided by density functional calculations at the same level of the theory. Vibrational mode analyses of the calculated Raman spectra reveal that the observed Raman bands above 700 cm(-1) are mainly associated with the in-plane deformation of the benzimidazolo moieties, while bands below 700 cm(-1) are associated with out-of-plane deformations of the benzimidazolo moieties. We have also found that for the nonresonance excited experimental Raman spectrum of aggregated-TTBC cation, the Raman bands in the higher-frequency region are enhanced compared with those in the nonresonance spectrum of the monomeric cation. For the experimental Raman spectrum of the aggregate under resonance excitation, however, we find new Raman features below 600 cm(-1), in addition to a significantly enhanced Raman peak at 671 cm(-1) that are associated with out-of-plane distortions. Also, time-dependent density functional theory calculations suggest that the experimentally observed electronic transition at ∼515 nm (i.e., 2.41 eV) in the absorption spectrum of the monomeric-TTBC cation predominantly results from the π → π∗ transition. Calculations are further interpreted

  5. UV photostability of insect repellents evaluated through Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bório, Viviane G.; Fernandes, Adjaci U.; Silveira, Landulfo

    2016-02-01

    The use of insect repellents either indoors or at places with incidence of solar radiation has been common due to dengue epidemics in Brazil. The lack of studies on the photostability of these substances has motivated this study, where the main goal was to verify the photostability and photodegradation of some of the commercially insect repellents available under the simulated ultraviolet (UV) radiation, by evaluating the molecular changes using dispersive Raman spectroscopy (830 nm excitation). A laboratory-made chamber was used for irradiating the repellents, where UV-A + UV-B radiations (UV-A: 5.5 mW/cm2 and UV-B 1.5 mW/cm2) can be obtained. The chamber internal temperature did not exceed 31 °C during experiments. The compounds n,n-diethyl-m-toluamide (DEET), IR-3535, andiroba and citronella oils, used as active ingredients in insect repellents, and commercial formula containing DEET (14.5% in ethanol and isopropyl myristate) and IR-3535 (16% in carbopol) were continuously irradiated for 8 h. The Raman spectrum of each sample was obtained before and after UV exposure. The compounds and the commercial formula containing IR-3535 showed photo-stability when irradiated, since no changes in the peaks were found. The commercial formula containing DEET showed spectral decrease at 524, 690, 1003 and 1606 cm-1, assigned to the DEET, and increase at 884 cm-1, assigned to the ethanol. These results indicate that the excipient could influence the photostability of the active ingredient. The Raman spectroscopy can be suitable to monitor the photodegradation under UV irradiation rapidly and reliably.

  6. Electrochemical tip-enhanced Raman spectroscopy (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Zeng, Zhicong; Huang, Shengchao; Huang, Tengxiang; Li, Maohua; Ren, Bin

    2015-08-01

    Tip-enhanced Raman spectroscopy (TERS) can not only provide very high sensitivity but also high spatial resolution, and has found applications in various fields, including surface science, materials, and biology. Most of previous TERS studies were performed in air or in the ultrahigh vacuum. If TERS study can be performed in the electrochemical environment, the electronic properties of the surface can be well controlled so that the interaction of the molecules with the substrate and the configuration of the molecules on the surface can also be well controlled. However, the EC-TERS is not just a simple combination of electrochemistry with TERS, or the combination of EC-STM with Raman. It is a merge of STM, electrochemistry and Raman spectroscopy, and the mutual interference among these techniques makes the EC-TERS particularly challenge: the light distortion in EC system, the sensitivity, the tip coating to work under EC-STM and retain the TERS activity and cleanliness. We designed a special spectroelectrochemical cell to eliminate the distortion of the liquid layer to the optical path and obtain TER spectra of reasonably good signal to noise ratio for surface adsorbed molecules under electrochemical potential control. For example, potential dependent TERS signal have been obtained for adsorbed aromatic thiol molecule, and much obvious signal change compared with SERS has been found, manifesting the importance of EC-TERS to reveal the interfacial structure of an electrochemical system. We further extended EC-TERS to electrochemical redox system, and clear dependence of the species during redox reaction can be identified.

  7. THE ROLE OF RAMAN SPECTROSCOPY IN THE ANALYTICAL CHEMISTRY OF POTABLE WATER

    EPA Science Inventory

    Advances in instrumentation are making Raman spectroscopy the tool of choice for an increasing number of chemical applications. For example, many recalcitrant industrial process monitoring problems have been solved in recent years with in-line Raman spectrometers. Raman is attr...

  8. Probing the Interaction at the Nano–Bio Interface Using Raman Spectroscopy: ZnO Nanoparticles and Adenosine Triphosphate Biomolecules

    PubMed Central

    2015-01-01

    With the advent of nanobiotechnology, there will be an increase in the interaction between engineered nanomaterials and biomolecules. Nanoconjugates with cells, organelles, and intracellular structures containing DNA, RNA, and proteins establish sequences of nano–bio boundaries that depend on several intricate complex biophysicochemical reactions. Given the complexity of these interactions, and their import in governing life at the molecular level, it is extremely important to begin to understand such nanoparticle–biomaterial association. Here we report a unique method of probing the kinematics between an energy biomolecule, adenosine triphosphate (ATP), and hydrothermally synthesized ZnO nanostructures using micro Raman spectroscopy, X-ray diffraction, and electron microscopy experiments. For the first time we have shown by Raman spectroscopy analysis that the ZnO nanostructures interact strongly with the nitrogen (N7) atom in the adenine ring of the ATP biomolecule. Raman spectroscopy also confirms the importance of nucleotide base NH2 group hydrogen bonding with water molecules and phosphate group ionization and their pH dependence. Calculation of molecular bond force constants from Raman spectroscopy reinforces our experimental data. These data present convincing evidence of pH-dependent interactions between ATP and zinc oxide nanomaterials. Significantly, Raman spectroscopy is able to probe such difficult to study and subtle nano–bio interactions and may be applied to elegantly elucidate the nano–bio interface more generally. PMID:25152799

  9. Raman spectroscopy and SERS analysis of ovarian tumour derived exosomes (TEXs): a preliminary study

    NASA Astrophysics Data System (ADS)

    Kerr, Laura T.; Gubbins, Luke; Weiner Gorzel, Karolina; Sharma, Shiva; Kell, Malcolm; McCann, Amanda; Hennelly, Bryan M.

    2014-05-01

    Here we report a preliminary study based on the application of Raman spectroscopy and surface enhanced Raman spectroscopy (SERS) to investigate the compositional differences between exosomes derived from ovarian carcinoma cells (cell line A2780) grown in normoxia (normal O2 conditions) and hypoxia (1% O2 conditions). Exosomes are integral to cell signalling, and are of interest in the study of how cells communicate within their environment. We are particularly interested in identifying whether hypoxia induced senescent cells can communi- cate via exosomes with neighbouring tumour cells, thereby causing them to become senescent and therefore radio and chemo resistant. With this goal in mind, we performed a preliminary study on the application of Raman spectroscopy and SERS to analyse the biomolecular fingerprint of both groups of exosomes and to investigate whether there exists a different biomolecular composition associated with exosomes derived from hypoxic cells in comparison to those from normoxic cells. We also applied multivariate statistical techniques for the classification of both groups of exosomes.

  10. Determination of Young's Modulus of Graphene by Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lee, Jae-Ung; Yoon, Duhee; Cheong, Hyeonsik

    2012-02-01

    The mechanical properties of graphene are interesting research subjects because its Young's modulus and strength are extremely high. Values of ˜1 TPa for the Young's modulus have been reported [Lee et al. Science, 321, 385 (2008), Koenig et al. Nat. Nanotech. 6, 543 (2011)]. We made a graphene sample on a SiO2/Si substrate with closed-bottom holes by mechanical exfoliation. A pressure difference across the graphene membrane was applied by putting the sample in a vacuum chamber. This pressure difference makes the graphene membrane bulge upward like a balloon. By measuring the shifts of the Raman G and 2D bands, we estimated the amount of strain on the graphene membrane. By comparing the strain estimated from the Raman measurements with numerical simulations based on the finite element method, we obtained the Young's modulus of graphene.

  11. Multi-excitation Raman difference spectroscopy based on modified multi-energy constrained iterative deconvolution algorithm

    NASA Astrophysics Data System (ADS)

    Zou, Wenlong; Cai, Zhijian; Zhou, Hongwu; Wu, Jianhong

    2013-12-01

    Raman spectroscopy is fast and nondestructive, and it is widely used in chemistry, biomedicine, food safety and other areas. However, Raman spectroscopy is often hampered by strong fluorescence background, especially in food additives detection and biomedicine researching. In this paper, one efficient technique was the multi-excitation Raman difference spectroscopy (MERDS) which incorporated a series of small wavelength-shift wavelengths as excitation sources. A modified multi-energy constrained iterative deconvolution (MMECID) algorithm was proposed to reconstruct the Raman Spectroscopy. Computer simulation and experiments both demonstrated that the Raman spectrum can be well reconstructed from large fluorescence background. The more excitation sources used, the better signal to noise ratio got. However, many excitation sources were equipped on the Raman spectrometer, which increased the complexity of the experimental system. Thus, a trade-off should be made between the number of excitation frequencies and experimental complexity.

  12. The study of interaction between graphene and metals by Raman spectroscopy

    SciTech Connect

    Wang, W. X.; Liang, S. H.; Yu, T.; Han, X. F.; Li, D. H.; Li, Y. B.

    2011-04-01

    Different metal films (Co, Ni, Au, and Ag) were deposited on graphene and the interactions between these metals and graphene were studied by Raman spectroscopy. The Raman peaks were shifted after the deposition of metal films. The electron doping of graphene with cobalt contacts and the hole doping with the nickel contacts are the main reasons for Raman peak shift. However, for gold contacts and silver contacts with graphene, strain effect dominates Raman peak shift instead of charge transfer.

  13. 2 nm continuously tunable 488nm micro-integrated diode-laser-based SHG light source for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Braune, M.; Maiwald, M.; Sumpf, B.; Tränkle, G.

    2016-04-01

    Raman spectroscopy in the visible spectral range is of great interest due to resonant Raman effects. Nevertheless, fluorescence and ambient light can mask the weak Raman lines. Shifted excitation Raman difference spectroscopy is a demonstrated tool to overcome this drawback. To apply this method, a light source with two alternating wavelengths is necessary. The spectral distance between these two wavelengths has to be adapted to the width of the Raman signal. According to the sample under investigation the width of the Raman signal could be in the range of 3 cm-1 - 12 cm-1. In this work, a micro-integrated light source emitting at 488 nm with a continuous wavelength tuning range up to 2 nm (83 cm-1) is presented. The pump source, a DFB laser emitting at 976 nm, and a periodically poled lithium niobate (PPLN) ridge waveguide crystal is used for the second harmonic generation (SHG). Both components are mounted on a μ-Peltier-element for temperature control. Here, a common wavelength tuning of the pump wavelength and the acceptance bandwidth of the SHG crystal via temperature is achieved. With the results the light source is suitable for portable Raman and SERDS experiments with a flexible spectral distance between both excitation wavelengths for SERDS with respect to the sample under investigation.

  14. Near-infrared confocal micro-Raman spectroscopy combined with PCA-LDA multivariate analysis for detection of esophageal cancer

    NASA Astrophysics Data System (ADS)

    Chen, Long; Wang, Yue; Liu, Nenrong; Lin, Duo; Weng, Cuncheng; Zhang, Jixue; Zhu, Lihuan; Chen, Weisheng; Chen, Rong; Feng, Shangyuan

    2013-06-01

    The diagnostic capability of using tissue intrinsic micro-Raman signals to obtain biochemical information from human esophageal tissue is presented in this paper. Near-infrared micro-Raman spectroscopy combined with multivariate analysis was applied for discrimination of esophageal cancer tissue from normal tissue samples. Micro-Raman spectroscopy measurements were performed on 54 esophageal cancer tissues and 55 normal tissues in the 400-1750 cm-1 range. The mean Raman spectra showed significant differences between the two groups. Tentative assignments of the Raman bands in the measured tissue spectra suggested some changes in protein structure, a decrease in the relative amount of lactose, and increases in the percentages of tryptophan, collagen and phenylalanine content in esophageal cancer tissue as compared to those of a normal subject. The diagnostic algorithms based on principal component analysis (PCA) and linear discriminate analysis (LDA) achieved a diagnostic sensitivity of 87.0% and specificity of 70.9% for separating cancer from normal esophageal tissue samples. The result demonstrated that near-infrared micro-Raman spectroscopy combined with PCA-LDA analysis could be an effective and sensitive tool for identification of esophageal cancer.

  15. Nondestructive evaluation of internal maturity of tomatoes using spatially offset Raman spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research explored the use of spatially offset Raman spectroscopy (SORS) for nondestructive evaluation of internal maturity of tomatoes. A Raman spectroscopy system using a 785 nm laser was developed to collect spatially-offset spectra in the wavenumber range of 200 – 2500. The SORS measuremen...

  16. The 14th Annual James L. Waters Symposium at Pittcon: Raman Spectroscopy

    ERIC Educational Resources Information Center

    Gardner, Charles W.

    2007-01-01

    Raman Spectroscopy was the main topic of the 14th Annual James L. Waters Symposium, which was held in March 2003 at Pittcon. The development of the enabling technologies that have made Raman spectroscopy a routine analysis tool in many laboratories worldwide is discussed.

  17. [Research Progress of Raman Spectroscopy on Dyestuff Identification of Ancient Relics and Artifacts].

    PubMed

    He, Qiu-ju; Wang, Li-qin

    2016-02-01

    As the birthplace of Silk Road, China has a long dyeing history. The valuable information about the production time, the source of dyeing material, dyeing process and preservation status were existed in organic dyestuff deriving from cultural relics and artifacts. However, because of the low contents, complex compositions and easily degraded of dyestuff, it is always a challenging task to identify the dyestuff in relics analyzing field. As a finger-print spectrum, Raman spectroscopy owns unique superiorities in dyestuff identification. Thus, the principle, characteristic, limitation, progress and development direction of micro-Raman spectroscopy (MRS/µ-Raman), near infrared reflection and Fourier transform Raman spectroscopy (NIR-FT-Raman), surface-enhanced Raman spectroscopy (SERS) and resonance raman spectroscopy (RRS) have been introduced in this paper. Furthermore, the features of Raman spectra of gardenia, curcumin and other natural dyestuffs were classified by MRS technology, and then the fluorescence phenomena of purpurin excitated with different wavelength laser was compared and analyzed. At last, gray green silver colloidal particles were made as the base, then the colorant of madder was identified combining with thin layer chromatography (TLC) separation technology and SERS, the result showed that the surface enhancement effect of silver colloidal particles could significantly reduce fluorescence background of the Raman spectra. It is pointed out that Raman spectroscopy is a rapid and convenient molecular structure qualitative methodology, which has broad application prospect in dyestuff analysis of cultural relics and artifacts. We propose that the combination of multi-Raman spectroscopy, separation technology and long distance transmission technology are the development trends of Raman spectroscopy. PMID:27209739

  18. Characterization and differentiation of normal and abnormal semen samples using micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Huang, Zufang; Chen, Xiwen; Chen, Jinhua; Li, Yongzeng; Lei, Jinping; Chen, Rong

    2012-12-01

    Growth in the percentage of male infertility has caused extensive concerns. The fast and reliable method is urgently required for diagnosis of semen samples. In our study, micro-Raman spectroscopy was employed to characterize and differentiate the normal and abnormal semen samples based on the differences of their specific Raman spectra which originated from biochemical components. Our preliminary results demonstrate that micro-Raman spectroscopy combined with multivariate analysis methods has the potential of being used to detect and differentiate semen samples.

  19. Application of micro-Raman and Photoluminescence spectroscopy to defect and thin film characterization

    NASA Astrophysics Data System (ADS)

    Conti, Giuseppina; Uritsky, Yuri; Brundle, C. R.

    2001-01-01

    Applications of micro-Raman and micro-Photoluminescence spectroscopy to defect and thin film characterization in semiconductor processing and equipment development are presented. The Raman spectrometer is coupled to a confocal laser Defect Review Tool (DRT). This system locates particles as small as 0.2 μm, both on 200 mm and 300 mm wafers. Raman spectroscopy is fast, non-destructive, can be performed in ambient, and is capable of providing chemical state and structural (phases, stress) information down to sub-micron dimension. Its application is material specific, however, since some materials do not have Raman-active vibrations or sufficient cross-section, or have a probing depth too long (optically transparent) to be useful. In general, chemical state information is obtainable from vibrational fingerprints of covalently bonded compounds (organic, Si-H, Si-Si, etc.), some ceramics (e.g. Zr-O, Al-O etc.), and ionic species (e.g. ammonium salts). Structural information, such as residual stress (e.g. poly-Si) and phase distinction (e.g. amorphous/diamond carbon; high/low residual phases of silicide) can sometimes also be obtained. Specific examples from Applied Materials development programs are presented. These include identification and distinction of carbon particles from different hardware sources generated by NF3 clean; organic defects on Cu after CMP; identification of the compound causing Br based particles after poly-gate etch; and distinction between ceramic based aluminum particles and anodized based aluminum particles. In the area of thin film characterization we have used micro-Raman to characterize residual build-up on hardware (e.g. residue from showerhead used in the W-CVD process chamber), and the process development of coatings and film products (e.g. diamond, poly-Si).

  20. Identification of anisodamine tablets by Raman and near-infrared spectroscopy with chemometrics

    NASA Astrophysics Data System (ADS)

    Li, Lian; Zang, Hengchang; Li, Jun; Chen, Dejun; Li, Tao; Wang, Fengshan

    2014-06-01

    Vibrational spectroscopy including Raman and near-infrared (NIR) spectroscopy has become an attractive tool for pharmaceutical analysis. In this study, effective calibration models for the identification of anisodamine tablet and its counterfeit and the distinguishment of manufacturing plants, based on Raman and NIR spectroscopy, were built, respectively. Anisodamine counterfeit tablets were identified by Raman spectroscopy with correlation coefficient method, and the results showed that the predictive accuracy was 100%. The genuine anisodamine tablets from 5 different manufacturing plants were distinguished by NIR spectroscopy using partial least squares discriminant analysis (PLS-DA) models based on interval principal component analysis (iPCA) method. And the results showed the recognition rate and rejection rate were 100% respectively. In conclusion, Raman spectroscopy and NIR spectroscopy combined with chemometrics are feasible and potential tools for rapid pharmaceutical tablet discrimination.

  1. Application of Raman spectroscopy in Andrology: non-invasive analysis of tissue and single cell

    PubMed Central

    Liu, Yufei; Zhu, Yong

    2014-01-01

    As a fast, label-free and non-invasive detection method, Raman spectroscopy has been widely used for the interrogation of biological tissues, any alterations of molecular structure and chemical components during pathological processes would be identified and revealed via the differences on Raman spectrum. In clinics, the Raman spectroscopy has great potentials to provide real-time scanning of living tissues and fast diagnosis of diseases, just like discrimination of various carcinomas. A portable Raman spectroscopy which combined Raman system with an optical fiber probe has also been developed and proved to be able to provide intraoperative assistance in both human study and animal models. In Andrology, interests in Raman spectroscopy had just emerged. In this review, we summarized the progress about the utility of Raman spectroscopy in Andrology, the literatures were gathered from PubMed and Ovid database using MeSH terms associated with prostate, testis, seminal plasma and single sperm cell. We also highlighted the serious challenges as to the final clinical application of Raman technique. In conclusion, research in Raman spectroscopy may herald a new era for Andrology. PMID:26816760

  2. Classification of oral cancers using Raman spectroscopy of serum

    NASA Astrophysics Data System (ADS)

    Sahu, Aditi; Talathi, Sneha; Sawant, Sharada; Krishna, C. Murali

    2014-03-01

    Oral cancers are the sixth most common malignancy worldwide, with low 5-year disease free survival rates, attributable to late detection due to lack of reliable screening modalities. Our in vivo Raman spectroscopy studies have demonstrated classification of normal and tumor as well as cancer field effects (CFE), the earliest events in oral cancers. In view of limitations such as requirement of on-site instrumentation and stringent experimental conditions of this approach, feasibility of classification of normal and cancer using serum was explored using 532 nm excitation. In this study, strong resonance features of β-carotenes, present differentially in normal and pathological conditions, were observed. In the present study, Raman spectra of sera of 36 buccal mucosa, 33 tongue cancers and 17 healthy subjects were recorded using Raman microprobe coupled with 40X objective using 785 nm excitation, a known source of excitation for biomedical applications. To eliminate heterogeneity, average of 3 spectra recorded from each sample was subjected to PC-LDA followed by leave-one-out-cross-validation. Findings indicate average classification efficiency of ~70% for normal and cancer. Buccal mucosa and tongue cancer serum could also be classified with an efficiency of ~68%. Of the two cancers, buccal mucosa cancer and normal could be classified with a higher efficiency. Findings of the study are quite comparable to that of our earlier study, which suggest that there exist significant differences, other than β- carotenes, between normal and cancerous samples which can be exploited for the classification. Prospectively, extensive validation studies will be undertaken to confirm the findings.

  3. Surface enhanced Raman spectroscopy on a flat graphene surface

    PubMed Central

    Xu, Weigao; Ling, Xi; Xiao, Jiaqi; Dresselhaus, Mildred S.; Kong, Jing; Xu, Hongxing; Liu, Zhongfan; Zhang, Jin

    2012-01-01

    Surface enhanced Raman spectroscopy (SERS) is an attractive analytical technique, which enables single-molecule sensitive detection and provides its special chemical fingerprints. During the past decades, researchers have made great efforts towards an ideal SERS substrate, mainly including pioneering works on the preparation of uniform metal nanostructure arrays by various nanoassembly and nanotailoring methods, which give better uniformity and reproducibility. Recently, nanoparticles coated with an inert shell were used to make the enhanced Raman signals cleaner. By depositing SERS-active metal nanoislands on an atomically flat graphene layer, here we designed a new kind of SERS substrate referred to as a graphene-mediated SERS (G-SERS) substrate. In the graphene/metal combined structure, the electromagnetic “hot” spots (which is the origin of a huge SERS enhancement) created by the gapped metal nanoislands through the localized surface plasmon resonance effect are supposed to pass through the monolayer graphene, resulting in an atomically flat hot surface for Raman enhancement. Signals from a G-SERS substrate were also demonstrated to have interesting advantages over normal SERS, in terms of cleaner vibrational information free from various metal-molecule interactions and being more stable against photo-induced damage, but with a comparable enhancement factor. Furthermore, we demonstrate the use of a freestanding, transparent and flexible “G-SERS tape” (consisting of a polymer-layer-supported monolayer graphene with sandwiched metal nanoislands) to enable direct, real time and reliable detection of trace amounts of analytes in various systems, which imparts high efficiency and universality of analyses with G-SERS substrates. PMID:22623525

  4. Interfacial processes studied by coupling electrochemistry at the polarised liquid-liquid interface with in situ confocal Raman spectroscopy.

    PubMed

    Poltorak, Lukasz; Dossot, Manuel; Herzog, Grégoire; Walcarius, Alain

    2014-12-28

    Interfacial processes controlled by ion transfer voltammetry at the interface between two immiscible electrolyte solutions were studied by in situ Raman spectroscopy. Raman spectra of the interface between a 5 mM NaCl aqueous solution and 10 mM bis(triphenyl-phosphoranydieneammonium) tetrakis(4-chlorophenyl)borate in 1,2-dichloroethane were recorded at open circuit potential and at various interfacial potential differences. At open-circuit potential, Raman peaks assigned to vibrational modes of 1,2-dichloroethane are clearly visible and peaks of weak intensity are measured for the organic electrolyte ions. When a negative interfacial potential difference is applied, the intensity of the peaks of the cation of the organic electrolyte increases, confirming its transfer induced by the interfacial potential difference applied. The electrochemically assisted generation of mesoporous silica deposits was then followed by in situ confocal Raman spectroscopy. The condensation of mesoporous silica was controlled by the transfer of cetyltrimethylammonium (CTA(+)) ions to an aqueous phase containing hydrolysed silanes. The transfer of CTA(+) at the interface was monitored in situ by confocal Raman spectroscopy, and formation of silica was observed. PMID:25377062

  5. Resonance Raman spectroscopy of volatile organics -- Carbon tetrachloride

    SciTech Connect

    Barletta, R.E.; Veligdan, J.T.

    1994-09-01

    Volatile organic chemicals are a class of pollutants which are regulated at very low levels by the EPA. Consequently a need exists as a part of site remediation efforts within DOE to develop technologies which will allow for the in situ monitoring of these chemicals. Resonance Raman spectroscopy is a potential technique to accomplish this if the resonance enhancement is sufficiently high. Carbon tetrachloride was selected as a test case. Measurements under resonance conditions at 248 nm showed an enhancement factor of 2 {times} 10{sup 4}. Using this value an estimate of the sensitivity for both in situ and remote monitoring of CCl{sup 4} was made. It was concluded that resonance Raman could be used to detect these chemicals at levels of regulatory interest. Future effort directed towards the development of a suitable probe as well as a field-portable system would be desirable. Such effort could be directed towards the solution of a particular monitoring problem within a DOE waste remediation project. Once developed, however, it should be easily generalized to the analysis of other VOC`s in other environments.

  6. Diagnosing breast cancer using Raman spectroscopy: prospective analysis

    PubMed Central

    Haka, Abigail S.; Volynskaya, Zoya; Gardecki, Joseph A.; Nazemi, Jon; Shenk, Robert; Wang, Nancy; Dasari, Ramachandra R.; Fitzmaurice, Maryann; Feld, Michael S.

    2009-01-01

    We present the first prospective test of Raman spectroscopy in diagnosing normal, benign, and malignant human breast tissues. Prospective testing of spectral diagnostic algorithms allows clinicians to accurately assess the diagnostic information contained in, and any bias of, the spectroscopic measurement. In previous work, we developed an accurate, internally validated algorithm for breast cancer diagnosis based on analysis of Raman spectra acquired from fresh-frozen in vitro tissue samples. We currently evaluate the performance of this algorithm prospectively on a large ex vivo clinical data set that closely mimics the in vivo environment. Spectroscopic data were collected from freshly excised surgical specimens, and 129 tissue sites from 21 patients were examined. Prospective application of the algorithm to the clinical data set resulted in a sensitivity of 83%, a specificity of 93%, a positive predictive value of 36%, and a negative predictive value of 99% for distinguishing cancerous from normal and benign tissues. The performance of the algorithm in different patient populations is discussed. Sources of bias in the in vitro calibration and ex vivo prospective data sets, including disease prevalence and disease spectrum, are examined and analytical methods for comparison provided. PMID:19895125

  7. Probing of different conformations of piperazine using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    SenGupta, Sumana; Maiti, Nandita; Chadha, Ridhima; Kapoor, Sudhir

    2014-06-01

    Piperazine exists in a number of energetically close structural conformations, and here, we investigated the dependence of their relative abundance on the surrounding conditions by using Raman and SERS spectroscopy in pure solid, aqueous solution and Ag hydrosol. The experimental results were interpreted by DFT calculations using B3LYP functional with aug-cc-pvdz/LANL2DZ basis sets. In the chair form of piperazine, which is more stable than the skewed boat by ∼8 kcal mol-1, the two N-H bonds can remain equatorial or axial, leading to three different conformations, eq-eq, eq-ax and ax-ax. The calculated Raman spectrum of the lowest energy eq-eq conformation corresponds well with the experimental spectrum in pure solid, indicating eq-eq to be predominant. But, the contribution of the eq-ax conformation was found to be maximum in aqueous solution. The SERS spectrum revealed that eq-ax conformation was preferably adopted as piperazine was adsorbed vertically through its axial N-atom over silver nanoparticle surface.

  8. Diagnosing breast cancer using Raman spectroscopy: prospective analysis

    NASA Astrophysics Data System (ADS)

    Haka, Abigail S.; Volynskaya, Zoya; Gardecki, Joseph A.; Nazemi, Jon; Shenk, Robert; Wang, Nancy; Dasari, Ramachandra R.; Fitzmaurice, Maryann; Feld, Michael S.

    2009-09-01

    We present the first prospective test of Raman spectroscopy in diagnosing normal, benign, and malignant human breast tissues. Prospective testing of spectral diagnostic algorithms allows clinicians to accurately assess the diagnostic information contained in, and any bias of, the spectroscopic measurement. In previous work, we developed an accurate, internally validated algorithm for breast cancer diagnosis based on analysis of Raman spectra acquired from fresh-frozen in vitro tissue samples. We currently evaluate the performance of this algorithm prospectively on a large ex vivo clinical data set that closely mimics the in vivo environment. Spectroscopic data were collected from freshly excised surgical specimens, and 129 tissue sites from 21 patients were examined. Prospective application of the algorithm to the clinical data set resulted in a sensitivity of 83%, a specificity of 93%, a positive predictive value of 36%, and a negative predictive value of 99% for distinguishing cancerous from normal and benign tissues. The performance of the algorithm in different patient populations is discussed. Sources of bias in the in vitro calibration and ex vivo prospective data sets, including disease prevalence and disease spectrum, are examined and analytical methods for comparison provided.

  9. Two-step Raman spectroscopy method for tumor diagnosis

    NASA Astrophysics Data System (ADS)

    Zakharov, V. P.; Bratchenko, I. A.; Kozlov, S. V.; Moryatov, A. A.; Myakinin, O. O.; Artemyev, D. N.

    2014-05-01

    Two-step Raman spectroscopy phase method was proposed for differential diagnosis of malignant tumor in skin and lung tissue. It includes detection of malignant tumor in healthy tissue on first step with identification of concrete cancer type on the second step. Proposed phase method analyze spectral intensity alteration in 1300-1340 and 1640-1680 cm-1 Raman bands in relation to the intensity of the 1450 cm-1 band on first step, and relative differences between RS intensities for tumor area and healthy skin closely adjacent to the lesion on the second step. It was tested more than 40 ex vivo samples of lung tissue and more than 50 in vivo skin tumors. Linear Discriminant Analysis, Quadratic Discriminant Analysis and Support Vector Machine were used for tumors type classification on phase planes. It is shown that two-step phase method allows to reach 88.9% sensitivity and 87.8% specificity for malignant melanoma diagnosis (skin cancer); 100% sensitivity and 81.5% specificity for adenocarcinoma diagnosis (lung cancer); 90.9% sensitivity and 77.8% specificity for squamous cell carcinoma diagnosis (lung cancer).

  10. Raman spectroscopy of natron: shedding light on ancient Egyptian mummification.

    PubMed

    Edwards, Howell G M; Currie, Katherine J; Ali, Hassan R H; Jorge Villar, Susana E; David, A Rosalie; Denton, John

    2007-06-01

    The mummification ritual in ancient Egypt involved the evisceration of the corpse and its desiccation using natron, a naturally occurring evaporitic mineral deposit from the Wadi Natrun, Egypt. The deposit typically contains sodium carbonate, sodium bicarbonate and impurities of chloride and sulfate as its major elemental components. It is believed that the function of the natron was to rapidly remove the water from the cadaver to prevent microbial attack associated with subsequent biological tissue degradation and putrefaction. Several specimens of natron that were recently collected from the Wadi Natrun contained coloured zones interspersed with the mineral matrix that are superficially reminiscent of extremophilic cyanobacterial colonisation found elsewhere in hot and cold deserts. Raman spectroscopy of these specimens using visible and near-infrared laser excitation has revealed not only the mineral composition of the natron, but also evidence for the presence of cyanobacterial colonies in several coloured zones observed in the mineral matrix. Key Raman biosignatures of carotenoids, scytonemin and chlorophyll have been identified. PMID:17404715

  11. Probing the reaction coordinate for ligand binding in hemoglobin using ultrafast transient Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Huiping; Lingle, Robert, Jr.; Xu, Xiaobing; Hopkins, John B.

    1993-05-01

    Transient picosecond Raman spectroscopy is capable of differentiating vibrational relaxation from conformational changes by comparing the Stokes and anti-Stokes dynamics. We report pump-probe picosecond Raman experiments on oxy- and deoxyhemoglobin (oxyHb and deoxyHb, respectively) using 8 ps 532 nm pump pulses and 8 ps 355 nm probe pulses. Heme- to-protein vibrational cooling has been directly observed in deoxyHb for the first time, and the deconvolved cooling time constant is measured to be 2 - 5 ps. By applying our mode-specific Stokes and anti-Stokes technique to oxyHb, we find that any geminate recombination of photodeligated O2 must occur in either less than two picoseconds or longer than a nanosecond.

  12. Raman spectroscopy identifies radiation response in human non-small cell lung cancer xenografts

    NASA Astrophysics Data System (ADS)

    Harder, Samantha J.; Isabelle, Martin; Devorkin, Lindsay; Smazynski, Julian; Beckham, Wayne; Brolo, Alexandre G.; Lum, Julian J.; Jirasek, Andrew

    2016-02-01

    External beam radiation therapy is a standard form of treatment for numerous cancers. Despite this, there are no approved methods to account for patient specific radiation sensitivity. In this report, Raman spectroscopy (RS) was used to identify radiation-induced biochemical changes in human non-small cell lung cancer xenografts. Chemometric analysis revealed unique radiation-related Raman signatures that were specific to nucleic acid, lipid, protein and carbohydrate spectral features. Among these changes was a dramatic shift in the accumulation of glycogen spectral bands for doses of 5 or 15 Gy when compared to unirradiated tumours. When spatial mapping was applied in this analysis there was considerable variability as we found substantial intra- and inter-tumour heterogeneity in the distribution of glycogen and other RS spectral features. Collectively, these data provide unique insight into the biochemical response of tumours, irradiated in vivo, and demonstrate the utility of RS for detecting distinct radiobiological responses in human tumour xenografts.

  13. Linear and Nonlinear Calibration Methods for Predicting Mechanical Properties of Polypropylene Pellets Using Raman Spectroscopy.

    PubMed

    Banquet-Terán, Julio; Johnson-Restrepo, Boris; Hernández-Morelo, Alveiro; Ropero, Jorge; Fontalvo-Gomez, Miriam; Romañach, Rodolfo J

    2016-07-01

    A nondestructive and faster methodology to quantify mechanical properties of polypropylene (PP) pellets, obtained from an industrial plant, was developed with Raman spectroscopy. Raman spectra data were obtained from several types of samples such as homopolymer PP, random ethylene-propylene copolymer, and impact ethylene-propylene copolymer. Multivariate calibration models were developed by relating the changes in the Raman spectra to mechanical properties determined by ASTM tests (Young's traction modulus, tensile strength at yield, elongation at yield on traction, and flexural modulus at 1% secant). Several strategies were evaluated to build robust models including the use of preprocessing methods (baseline correction, vector normalization, de-trending, and standard normal variate), selecting the best subset of wavelengths to model property response and discarding irrelevant variables by applying genetic algorithm (GA). Linear multivariable models were investigated such as partial least square regression (PLS) and PLS with genetic algorithm (GA-PLS) while nonlinear models were implemented with artificial neural network (ANN) preceded by GA (GA-ANN). The best multivariate calibration models were obtained when a combination of genetic algorithms and artificial neural network were used on Raman spectral data with relative standard errors (%RSE) from 0.17 to 0.41 for training and 0.42 to 0.88% validation data sets. PMID:27287847

  14. Blind field test evaluation of Raman spectroscopy as a forensic tool.

    PubMed

    Harvey, S D; Vucelick, M E; Lee, R N; Wright, B W

    2002-01-24

    Analytical instrumentation for Raman spectroscopy has advanced rapidly in recent years to the point where commercial field-portable instruments are available. Raman analysis with portable instrumentation is a new capability that can provide emergency response teams with on-site evaluation of hazardous materials. Before Raman analysis is accepted and implemented in the field, realistic studies applied to unknown samples need to be performed to define the reliability of this technique. Studies described herein provide a rigorous blind field test that utilizes two instruments and two operators to analyze a matrix that consists of 58 unknown samples. Samples were searched against a custom hazardous materials reference library (Hazardous Material Response Unit (HMRU) Spectral Library Database). Experimental design included a number of intentionally difficult situations including binary solvent mixtures and a variety of compounds that yield medium-quality spectra that were not contained in the HMRU library. Results showed that over 97% of the samples were correctly identified with no occurrences of false positive identifications (compounds that were not in the library were never identified as library constituents). Statistical analysis indicated equivalent performance for both the operators and instruments. These results indicate a high level of performance that should extrapolate to actual field situations. Implementation of Raman techniques to emergency field situations should proceed with a corresponding level of confidence. PMID:11852198

  15. Ex vivo peripheral nerve detection of rats by spontaneous Raman spectroscopy

    PubMed Central

    Minamikawa, Takeo; Harada, Yoshinori; Takamatsu, Tetsuro

    2015-01-01

    Nerve-sparing surgery is increasingly being applied to avoid functional deficits of the limbs and organs following surgery. Peripheral nerves that should be preserved are, however, sometimes misidentified due to similarity of shape and color to non-nerve tissues. To avoid misidentification of peripheral nerves, development of an in situ nerve detection method is desired. In this study, we report the label-free detection of ex vivo peripheral nerves of Wistar rats by using Raman spectroscopy. We obtained Raman spectra of peripheral nerves (myelinated and unmyelinated nerves) and their adjacent tissues of Wistar rats without any treatment such as fixation and/or staining. For the identification of tissue species and further analysis of spectral features, we proposed a principal component regression-based discriminant analysis with representative Raman spectra of peripheral nerves and their adjacent tissues. Our prediction model selectively detected myelinated nerves and unmyelinated nerves of Wistar rats with respective sensitivities of 95.5% and 88.3% and specificities of 99.4% and 93.5%. Furthermore, important spectral features for the identification of tissue species were revealed by detailed analysis of principal components of representative Raman spectra of tissues. Our proposed approach may provide a unique and powerful tool for peripheral nerve detection for nerve-sparing surgery in the future. PMID:26602842

  16. Rapid detection of Listeria monocytogenes in milk using confocal micro-Raman spectroscopy and chemometric analysis.

    PubMed

    Wang, Junping; Xie, Xinfang; Feng, Jinsong; Chen, Jessica C; Du, Xin-jun; Luo, Jiangzhao; Lu, Xiaonan; Wang, Shuo

    2015-07-01

    Listeria monocytogenes is a facultatively anaerobic, Gram-positive, rod-shape foodborne bacterium causing invasive infection, listeriosis, in susceptible populations. Rapid and high-throughput detection of this pathogen in dairy products is critical as milk and other dairy products have been implicated as food vehicles in several outbreaks. Here we evaluated confocal micro-Raman spectroscopy (785 nm laser) coupled with chemometric analysis to distinguish six closely related Listeria species, including L. monocytogenes, in both liquid media and milk. Raman spectra of different Listeria species and other bacteria (i.e., Staphylococcus aureus, Salmonella enterica and Escherichia coli) were collected to create two independent databases for detection in media and milk, respectively. Unsupervised chemometric models including principal component analysis and hierarchical cluster analysis were applied to differentiate L. monocytogenes from Listeria and other bacteria. To further evaluate the performance and reliability of unsupervised chemometric analyses, supervised chemometrics were performed, including two discriminant analyses (DA) and soft independent modeling of class analogies (SIMCA). By analyzing Raman spectra via two DA-based chemometric models, average identification accuracies of 97.78% and 98.33% for L. monocytogenes in media, and 95.28% and 96.11% in milk were obtained, respectively. SIMCA analysis also resulted in satisfied average classification accuracies (over 93% in both media and milk). This Raman spectroscopic-based detection of L. monocytogenes in media and milk can be finished within a few hours and requires no extensive sample preparation. PMID:25863337

  17. [Analysis of pigments from Rhodotorula glutinis by Raman spectroscopy and thin layer chromatography].

    PubMed

    Yuan, Yu-feng; Tao, Zhan-hua; Wang, Xue; Li, Yong-qing; Liu, Jun-xian

    2012-03-01

    The pigments from Rhodotorula glutinis were separated by using thin layer chromatography, and the result showed that Rhodotorula glutinis cells could synthesize at least three kinds of pigments, which were beta-carotene, torulene, and torularhodin. The Raman spectra based on the three pigments were acquired, and original spectra were preprocessed by background elimination, baseline correction, and three-point-smoothing, then the averaged spectra from different pigments were investigated, and the result indicated that Raman shift which represents C-C bond was different, and the wave number of beta-carotene demonstrated the largest deviation, finally torulene and torularhodin in Rhodotorula glutinis had more content than beta-carotene. Quantitative analysis of Raman peak height ratio revealed that peak height ratio of pigments showed little difference, which could be used as parameters for further research on living cells, providing reference content of pigments. The above results suggest that Raman spectroscopy combined with thin layer chromatography can be applied to analyze pigments from Rhodotorula glutinis, provides abundant information about pigments, and serves as an effective method to study pigments. PMID:22582635

  18. Label-free discrimination of different stage nasopharyngeal carcinoma tissue based on Raman spectroscopy

    PubMed Central

    QIU, SUFANG; HUANG, QINGTING; HUANG, LINGLING; LIN, JINYONG; LU, JUN; LIN, DUO; CAO, GANG; CHEN, CHAO; PAN, JIANJI; CHEN, RONG

    2016-01-01

    The present study aimed to evaluate a label-free tissue test for the detection of nasopharyngeal carcinoma (NPC) at early and advanced stages using Raman spectroscopy (RS). RS measurements were performed to acquire high quality Raman spectra on two groups of tissue samples: One group consists of 30 NPC patients at the early stages (I–II), and the other group is 46 NPC patients at the advanced stages (III–IV). Tentative assignment of Raman bands showed specific biomolecular changes associated with cancer development. Furthermore, effective diagnostic algorithms based on principal components analysis (PCA) and linear discriminant analysis (LDA) were applied for distinguishing Raman spectra of nasopharyngeal tissues from different stages, yielding a diagnostic sensitivity of 70% and a specificity of 78%. This exploratory work suggests that RS in conjunction with the PCA-LDA algorithms provides good diagnostic ability for the early and the advanced staged NPC tissues, and RS has enormous potential for the non-invasive detection of early and advanced stage NPC. PMID:27073522

  19. Coherent two-dimensional terahertz-terahertz-Raman spectroscopy.

    PubMed

    Finneran, Ian A; Welsch, Ralph; Allodi, Marco A; Miller, Thomas F; Blake, Geoffrey A

    2016-06-21

    We present 2D terahertz-terahertz-Raman (2D TTR) spectroscopy, the first technique, to our knowledge, to interrogate a liquid with multiple pulses of terahertz (THz) light. This hybrid approach isolates nonlinear signatures in isotropic media, and is sensitive to the coupling and anharmonicity of thermally activated THz modes that play a central role in liquid-phase chemistry. Specifically, by varying the timing between two intense THz pulses, we control the orientational alignment of molecules in a liquid, and nonlinearly excite vibrational coherences. A comparison of experimental and simulated 2D TTR spectra of bromoform (CHBr3), carbon tetrachloride (CCl4), and dibromodichloromethane (CBr2Cl2) shows previously unobserved off-diagonal anharmonic coupling between thermally populated vibrational modes. PMID:27274067

  20. Raman spectroscopy of hot hydrogen above 200 GPa

    NASA Astrophysics Data System (ADS)

    Howie, Ross T.; Dalladay-Simpson, Philip; Gregoryanz, Eugene

    2015-05-01

    It has been theorized that at high pressure the increased energy of the zero-point oscillations in hydrogen would destabilize the lattice and form a ground fluid state at 0 K (ref. ). Theory has also suggested that this fluid state, representing a new state of matter, might have unusual properties governed by quantum effects, such as superfluidity or superconductivity. Here, by combining Raman spectroscopy and in situ high-temperature, high-pressure techniques, we demonstrate that above 200 GPa a new phase transition occurs as temperature is increased, for example 480 K at 255 GPa. If the transformation is interpreted as melting, it would be the lowest melting temperature of any material at these high pressures. We also find a new triple point between phases I and IV and the new phase, and demonstrate that hydrogen retains its molecular character around this point. These data may require a significant revision of the phase diagram of hydrogen above 200 GPa.

  1. Analysis of spreadable cheese by Raman spectroscopy and chemometric tools.

    PubMed

    Oliveira, Kamila de Sá; Callegaro, Layce de Souza; Stephani, Rodrigo; Almeida, Mariana Ramos; de Oliveira, Luiz Fernando Cappa

    2016-03-01

    In this work, FT-Raman spectroscopy was explored to evaluate spreadable cheese samples. A partial least squares discriminant analysis was employed to identify the spreadable cheese samples containing starch. To build the models, two types of samples were used: commercial samples and samples manufactured in local industries. The method of supervised classification PLS-DA was employed to classify the samples as adulterated or without starch. Multivariate regression was performed using the partial least squares method to quantify the starch in the spreadable cheese. The limit of detection obtained for the model was 0.34% (w/w) and the limit of quantification was 1.14% (w/w). The reliability of the models was evaluated by determining the confidence interval, which was calculated using the bootstrap re-sampling technique. The results show that the classification models can be used to complement classical analysis and as screening methods. PMID:26471577

  2. The microscopic structure of liquid methanol from Raman spectroscopy.

    PubMed

    Lin, Ke; Zhou, Xiaoguo; Luo, Yi; Liu, Shilin

    2010-03-18

    The microscopic structure of liquid methanol has been systematically investigated with Raman spectroscopy in a temperature range of 15-55 degrees C. The unbonded free -OH stretching vibrational band has been observed at approximately 3660 cm(-1) in pure liquid. With the aid of depolarization measurements and theoretical calculations, four featured spectral components have been unambiguously identified and assigned to four well-defined vibrational modes of clusters in chain or ring forms. Furthermore, the cluster size distribution and its temperature dependence have been derived from the spectral fittings for the first time, which lead to the conclusion that the trimer, tetramer, and pentamer are the dominant clusters in liquid methanol, taking up more than 50% of total clusters. PMID:20178325

  3. Monitoring the healing process of rat bones using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gamulin, O.; Serec, K.; Bilić, V.; Balarin, M.; Kosović, M.; Drmić, D.; Brčić, L.; Seiwerth, S.; Sikirić, P.

    2013-07-01

    The healing effect of BPC 157 on rat femoral head osteonecrosis was monitored by Raman spectroscopy. Three groups of rats were defined: an injured group treated with BPC 157 (10 μg/kg/daily ip), an injured control group (treated with saline, 5 ml/kg/daily ip), and an uninjured healthy group. The spectra were recorded and the healing effect assessed on samples harvested from animals which were sacrificed 3 and 6 weeks after being injured. The statistical analysis of the recorded spectra showed statistical differences between the BPC 157-treated, control, and healthy groups of animals. In particular, after 6 weeks the spectral resemblance between the healthy and BPC 157 samples indicated a positive BPC 157 influence on the healing process of rat femoral head.

  4. Towards ultrasensitive malaria diagnosis using surface enhanced Raman spectroscopy

    PubMed Central

    Chen, Keren; Yuen, Clement; Aniweh, Yaw; Preiser, Peter; Liu, Quan

    2016-01-01

    We report two methods of surface enhanced Raman spectroscopy (SERS) for hemozoin detection in malaria infected human blood. In the first method, silver nanoparticles were synthesized separately and then mixed with lysed blood; while in the second method, silver nanoparticles were synthesized directly inside the parasites of Plasmodium falciparum. It was observed that the first method yields a smaller variation in SERS measurements and stronger correlation between the estimated contribution of hemozoin and the parasitemia level, which is preferred for the quantification of the parasitemia level. In contrast, the second method yields a higher sensitivity to a low parasitemia level thus could be more effective in the early malaria diagnosis to determine whether a given blood sample is positive. PMID:26858127

  5. High-pressure polymorphism of acetylsalicylic acid (aspirin): Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Crowell, Ethan L.; Dreger, Zbigniew A.; Gupta, Yogendra M.

    2015-02-01

    Micro-Raman spectroscopy was used to elucidate the high-pressure polymorphic behavior of acetylsalicylic acid (ASA), an important pharmaceutical compound known as aspirin. Using a diamond anvil cell (DAC), single crystals of the two polymorphic phases of aspirin existing at ambient conditions (ASA-I and ASA-II) were compressed to 10 GPa. We found that ASA-I does not transform to ASA-II, but instead transforms to a new phase (ASA-III) above ∼2 GPa. It is demonstrated that this transformation primarily introduces structural changes in the bonding and arrangement of the acetyl groups and is reversible upon the release of pressure. In contrast, a less dense ASA-II shows no transition in the pressure range studied, though it appears to exhibit a disordered structure above 7 GPa. Our results suggest that ASA-III is the most stable polymorph of aspirin at high pressures.

  6. Glucose determination in human aqueous humor with Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Lambert, James L.; Pelletier, Christine C.; Borchert, Mark

    2005-01-01

    It has been suggested that spectroscopic analysis of the aqueous humor of the eye could be used to indirectly predict blood glucose levels in diabetics noninvasively. We have been investigating this potential using Raman spectroscopy in combination with partial least squares (PLS) analysis. We have determined that glucose at clinically relevant concentrations can be accurately predicted in human aqueous humor in vitro using a PLS model based on artificial aqueous humor. We have further determined that with proper instrument design, the light energy necessary to achieve clinically acceptable prediction of glucose does not damage the retinas of rabbits and can be delivered at powers below internationally acceptable safety limits. Herein we summarize our current results and address our strategies to improve instrument design. 2005 Society of Photo-Optical Instrumentation Engineers.

  7. Towards ultrasensitive malaria diagnosis using surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Chen, Keren; Yuen, Clement; Aniweh, Yaw; Preiser, Peter; Liu, Quan

    2016-02-01

    We report two methods of surface enhanced Raman spectroscopy (SERS) for hemozoin detection in malaria infected human blood. In the first method, silver nanoparticles were synthesized separately and then mixed with lysed blood; while in the second method, silver nanoparticles were synthesized directly inside the parasites of Plasmodium falciparum. It was observed that the first method yields a smaller variation in SERS measurements and stronger correlation between the estimated contribution of hemozoin and the parasitemia level, which is preferred for the quantification of the parasitemia level. In contrast, the second method yields a higher sensitivity to a low parasitemia level thus could be more effective in the early malaria diagnosis to determine whether a given blood sample is positive.

  8. Combining hyperspectral imaging and Raman spectroscopy for remote chemical sensing

    NASA Astrophysics Data System (ADS)

    Ingram, John M.; Lo, Edsanter

    2008-04-01

    The Photonics Research Center at the United States Military Academy is conducting research to demonstrate the feasibility of combining hyperspectral imaging and Raman spectroscopy for remote chemical detection over a broad area of interest. One limitation of future trace detection systems is their ability to analyze large areas of view. Hyperspectral imaging provides a balance between fast spectral analysis and scanning area. Integration of a hyperspectral system capable of remote chemical detection will greatly enhance our soldiers' ability to see the battlefield to make threat related decisions. It can also queue the trace detection systems onto the correct interrogation area saving time and reconnaissance/surveillance resources. This research develops both the sensor design and the detection/discrimination algorithms. The one meter remote detection without background radiation is a simple proof of concept.

  9. Raman spectroscopy and in situ Raman spectroelectrochemistry of isotopically engineered graphene systems.

    PubMed

    Frank, Otakar; Dresselhaus, Mildred S; Kalbac, Martin

    2015-01-20

    CONSPECTUS: The special properties of graphene offer immense opportunities for applications to many scientific fields, as well as societal needs, beyond our present imagination. One of the important features of graphene is the relatively simple tunability of its electronic structure, an asset that extends the usability of graphene even further beyond present experience. A direct injection of charge carriers into the conduction or valence bands, that is, doping, represents a viable way of shifting the Fermi level. In particular, electrochemical doping should be the method of choice, when higher doping levels are desired and when a firm control of experimental conditions is needed. In this Account, we focus on the electrochemistry of graphene in combination with in situ Raman spectroscopy, that is, in situ Raman spectroelectrochemistry. Such a combination of methods is indeed very powerful, since Raman spectroscopy not only can readily monitor the changes in the doping level but also can give information on eventual stress or disorder in the material. However, when Raman spectroscopy is employed, one of its main strengths lies in the utilization of isotope engineering during the chemical vapor deposition (CVD) growth of the graphene samples. The in situ Raman spectroelectrochemical study of multilayered systems with smartly designed isotope compositions in individual layers can provide a plethora of knowledge about the mutual interactions (i) between the graphene layers themselves, (ii) between graphene layers and their directly adjacent environment (e.g., substrate or electrolyte), and (iii) between graphene layers and their extended environment, which is separated from the layer by a certain number of additional graphene layers. In this Account, we show a few examples of such studies, from monolayer to two-layer and three-layer specimens and considering both turbostratic and AB interlayer ordering. Furthermore, the concept and the method can be extended further

  10. Advances in Raman spectroscopy for the diagnosis of Alzheimer's disease

    NASA Astrophysics Data System (ADS)

    Sudworth, Caroline D.; Archer, John K. J.; Black, Richard A.; Mann, David

    2006-02-01

    Within the next 50 years Alzheimer's disease is expected to affect 100 million people worldwide. The progressive decline in the mental health of the patient is caused by severe brain atrophy generated by the breakdown and aggregation of proteins, resulting in β-amyloid plaques and neurofibrillary tangles. The greatest challenge to Alzheimer's disease lies in the pursuit of an early and definitive diagnosis, in order that suitable treatment can be administered. At the present time, definitive diagnosis is restricted to post-mortem examination. Alzheimer's disease also remains without a long-term cure. This research demonstrates the potential role of Raman spectroscopy, combined with principle components analysis (PCA), as a diagnostic method. Analyses of ethically approved ex vivo post-mortem brain tissues (originating from frontal and occipital lobes) from control (3 normal elderly subjects and 3 Huntingdon's disease subjects) and Alzheimer's disease (12 subjects) brain sections, and a further set of 12 blinded samples are presented. Spectra originating from these tissues are highly reproducible, and initial results indicate a vital difference in protein content and conformation, relating to the abnormally high levels of aggregated proteins in the diseased tissues. Further examination of these spectra using PCA allows for the separation of control from diseased tissues. The validation of the PCA models using blinded samples also displays promise for the identification of Alzheimer's disease, in conjunction with secondary information regarding other brain diseases and dementias. These results provide a route for Raman spectroscopy as a possible non-invasive, non-destructive tool for the early diagnosis of Alzheimer's disease.

  11. Raman spectroscopy and DFT calculations of As(III) complexation with a cysteine-rich biomaterial.

    PubMed

    Teixeira, Mônica C; Ciminelli, Virgínia S T; Dantas, Maria Sylvia Silva; Diniz, Sirlaine F; Duarte, Hélio A

    2007-11-01

    Arsenite adsorption onto a protein-rich biomass and, more specifically, the chemical groups involved in the uptake were investigated using Raman spectroscopy and DFT calculations. The study was based on spectroscopic analyses of raw and arsenic-loaded biomass as well as standard samples of amino acids and arsenic salts. The predominant secondary structure of the protein was identified as the beta-sheet type, with some contribution from alpha-helix structures. The participation of sulphydryl groups from cystine/cysteine molecules during the adsorption of arsenite was demonstrated. Only the gauche-gauche-gauche (g-g-g) conformation type of the disulfide bonds was involved in arsenic complexation. The formation of a pyramidal trigonal As(HCys)(3) complex was modeled according to the density functional theory (DFT). The agreement of the DFT harmonic frequencies with the RAMAN spectra of the As(HCys)(3) complex demonstrated the relevant features of the cysteine-rich biomaterial regarding arsenic uptake as well as of the mechanism involved in the As(III)/biomass interaction at a molecular level. The results also illustrate that Raman spectroscopy can be successfully applied to investigate the mechanism of metal adsorption onto amorphous biomaterials. PMID:17707392

  12. Early detection of melanoma with the combined use of acoustic microscopy, infrared reflectance and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Karagiannis, Georgios T.; Grivas, Ioannis; Tsingotjidou, Anastasia; Apostolidis, Georgios K.; Grigoriadou, Ifigeneia; Dori, I.; Poulatsidou, Kyriaki-Nefeli; Doumas, Argyrios; Wesarg, Stefan; Georgoulias, Panagiotis

    2015-03-01

    Malignant melanoma is a form of skin cancer, with increasing incidence worldwide. Early diagnosis is crucial for the prognosis and treatment of the disease. The objective of this study is to develop a novel animal model of melanoma and apply a combination of the non-invasive imaging techniques acoustic microscopy, infrared (IR) and Raman spectroscopies, for the detection of developing tumors. Acoustic microscopy provides information about the 3D structure of the tumor, whereas, both spectroscopic modalities give qualitative insight of biochemical changes during melanoma development. In order to efficiently set up the final devices, propagation of ultrasonic and electromagnetic waves in normal skin and melanoma simulated structures was performed. Synthetic and grape-extracted melanin (simulated tumors), endermally injected, were scanned and compared to normal skin. For both cases acoustic microscopy with central operating frequencies of 110MHz and 175MHz were used, resulting to the tomographic imaging of the simulated tumor, while with the spectroscopic modalities IR and Raman differences among spectra of normal and melanin- injected sites were identified in skin depth. Subsequently, growth of actual tumors in an animal melanoma model, with the use of human malignant melanoma cells was achieved. Acoustic microscopy and IR and Raman spectroscopies were also applied. The development of tumors at different time points was displayed using acoustic microscopy. Moreover, the changes of the IR and Raman spectra were studied between the melanoma tumors and adjacent healthy skin. The most significant changes between healthy skin and the melanoma area were observed in the range of 900-1800cm-1 and 350-2000cm-1, respectively.

  13. Label-free analysis of cellular biochemistry by Raman spectroscopy and microscopy.

    PubMed

    Schie, Iwan W; Huser, Thomas

    2013-04-01

    We review the biomedical applications of Raman spectroscopy at the single cell and tissue level. Raman scattering is the inelastic scattering of light by molecular bonds resulting in a wealth of spectral bands, which enable the identification of biological materials and the nondestructive analysis of dynamic changes in their biochemistry. We briefly review the basics behind highly sensitive Raman spectroscopy and highlight recent applications to biomedical research. We discuss advanced chemometrics methods that are utilized to analyze Raman spectral data and which permit one, for example, to distinguish between normal and diseased cells or which enable one to follow the differentiation of stem cells without perturbing the cellular biochemistry. We also discuss advanced coherent Raman scattering techniques, such as coherent anti-Stokes Raman scattering and stimulated Raman scattering, which allow for the molecularly specific imaging of cells, tissues, and entire organisms in vitro and in vivo. PMID:23720335

  14. Ring-Down Spectroscopy for Characterizing a CW Raman Laser

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

    2007-01-01

    .A relatively simple technique for characterizing an all-resonant intracavity continuous-wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, characterizing signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes. Heretofore, in order to characterize resonant-cavity-based Raman lasers, it has usually been necessary to manipulate the frequencies and power levels of pump lasers and, in each case, to take several sets of measurements. In cases involving ultra-high-Q resonators, it also has been desirable to lock pump lasers to resonator modes to ensure the quality of measurement data. Simpler techniques could be useful. In the present ring-down spectroscopic technique, one infers the parameters of interest from the decay of the laser out of its steady state. This technique does not require changing the power or frequency of the pump laser or locking the pump laser to the resonator mode. The technique is based on a theoretical analysis of what happens when the pump laser is abruptly switched off after the Raman generation reaches the steady state. The analysis starts with differential equations for the evolution of the amplitudes of the pump and Stokes electric fields, leading to solutions for the power levels of the pump and Stokes fields as functions of time and of the aforementioned parameters. Among other things, these solutions show how the ring-down time depends, to some extent, on the electromagnetic energy accumulated in the cavity. The solutions are readily converted to relatively simple equations for the parameters as functions of quantities that can be determined from measurements of the time-dependent power levels. For example, the steady-state intracavity conversion efficiency is given by G1/G2 1 and the threshold power is given by Pin(G2/G1)2, where Pin is the steady-state input pump power immediately prior to

  15. Application of time-resolved resonance Raman spectroscopy to intramolecular electron transfer

    SciTech Connect

    Schoonover, J.R.; Strouse, G.F.; Chen, P.; Bates, D.; Meyer, T.J. )

    1993-06-09

    Time-resolved resonance Raman spectroscopy has been applied for the first time to the study of intramolecular electron transfer in a chromophore-quencher complex, based on a metal-to-ligand charge-transfer (MLCT) excited state. These measurements allow for (1) the identification of redox sites that are reached following excitation and (2) the inferring of structural information in short-lived intermediates. This technique is a more sensitive probe than transient absorption as shown by its application to the redox-separated complex shown below involving a pyridinium acceptor and a phenothiazine donor.

  16. Monitoring LED-induced carotenoid increase in grapes by Transmission Resonance Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gonzálvez, Alicia G.; Martínez, Nerea L.; Telle, Helmut H.; Ureña, Ángel González

    2013-02-01

    Transmission Resonance Raman (TRR) spectroscopy combines increased signal-to-noise ratio with enhanced analytical sensibility. TRR was applied to directly monitor, without any sample preparation, the enhancement of β-carotene content in table grapes when they are irradiated by low power UV-LEDs. It was shown that, with respect to control samples, the carotenoid content in the grapes increased about five-fold, using UV-LED irradiation doses being two orders of magnitude lower than the maximum limit allowed by United States Food and Drug Administration. These promising results may pave the way for the development of easy, non-invasive techniques to improve food quality.

  17. Identification and characterization of colorectal cancer using Raman spectroscopy and feature selection techniques.

    PubMed

    Li, Shaoxin; Chen, Gong; Zhang, Yanjiao; Guo, Zhouyi; Liu, Zhiming; Xu, Junfa; Li, Xueqiang; Lin, Lin

    2014-10-20

    This study aims to detect colorectal cancer with near-infrared Raman spectroscopy and feature selection techniques. A total of 306 Raman spectra of colorectal cancer tissues and normal tissues are acquired from 44 colorectal cancer patients. Five diagnostically important Raman bands in the regions of 815-830, 935-945, 1131-1141, 1447-1457 and 1665-1675 cm(-1) related to proteins, nucleic acids and lipids of tissues are identified with the ant colony optimization (ACO) and support vector machine (SVM). The diagnostic models built with the identified Raman bands provide a diagnostic accuracy of 93.2% for identifying colorectal cancer from normal Raman spectroscopy. The study demonstrates that the Raman spectroscopy associated with ACO-SVM diagnostic algorithms has great potential to characterize and diagnose colorectal cancer. PMID:25401621

  18. Raman and surface-enhanced Raman spectroscopy of amino acids and nucleotide bases for target bacterial vibrational mode identification

    NASA Astrophysics Data System (ADS)

    Guicheteau, Jason; Argue, Leanne; Hyre, Aaron; Jacobson, Michele; Christesen, Steven D.

    2006-05-01

    Raman and surface-enhanced Raman spectroscopy (SERS) studies of bacteria have reported a wide range of vibrational mode assignments associated with biological material. We present Raman and SER spectra of the amino acids phenylalanine, tyrosine, tryptophan, glutamine, cysteine, alanine, proline, methionine, asparagine, threonine, valine, glycine, serine, leucine, isoleucine, aspartic acid and glutamic acid and the nucleic acid bases adenosine, guanosine, thymidine, and uridine to better characterize biological vibrational mode assignments for bacterial target identification. We also report spectra of the bacteria Bacillus globigii, Pantoea agglomerans, and Yersinia rhodei along with band assignments determined from the reference spectra obtained.

  19. Fluorescence spectroscopy applied to orange trees

    NASA Astrophysics Data System (ADS)

    Marcassa, L. G.; Gasparoto, M. C. G.; Belasque, J., Jr.; Lins, E. C.; Dias Nunes, F.; Bagnato, V. S.

    2006-05-01

    In this work, we have applied laser-induced fluorescence spectroscopy to investigate biological processes in orange trees (Citrus aurantium L.). We have chosen to investigate water stress and Citrus Canker, which is a disease caused by the Xanthomonas axonopodis pv. citri bacteria. The fluorescence spectroscopy was investigated by using as an excitation source a 442-nm 15-mW HeCd gas multimode discharge laser and a 532-nm 10-mW Nd3+:YAG laser. The stress manifestation was detected by the variation of fluorescence ratios of the leaves at different wavelengths. The fluorescence ratios present a significant variation, showing the possibility to observe water stress by fluorescence spectrum. The Citrus Canker’s contaminated leaves were discriminated from the healthy leaves using a more complex analysis of the fluorescence spectra. However, we were unable to discriminate it from another disease, and new fluorescence experiments are planned for the future.

  20. Analysis of hydrocarbon fuel properties by means of Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Flatley, Martin W.

    The project is focused on the determination of Raman spectra of hydrocarbon fuel samples using a spectrometer employing a silicon linear array detector which has a spectral range of 400 nm to 1.1 mum. The spectra are processed using chemometric techniques in order to determine the concentrations of the tracked blend components and analytical values that are used to ensure that desired specifications are achieved. The verification is based on the American Standard Testing Methods procedures for the determination of the motor, research, and road octane numbers, simulated distillation and Reid vapour pressure. Blending is one of the most important steps in the final production of hydrocarbon fuels; as many as ten complex components are mixed to achieve the desired properties of the final product. Traditionally, blending relies on well-established analytical methods such as gas chromatography for component and simulated distillation analysis, knock engines and near infrared spectroscopy for octane analysis. All of these methods are reliable and accurate, but their results are not available in real time but rather with a substantial delay, since it is in the nature of the methods that the sample must be transported from a test site to the site where the instrument is located. Additional time is required for performing the analytical procedure; e.g. the results of a gas chromatography analysis are only available from minutes to hours after the sample has been introduced into the instrument. Consequently, the results, although accurate, become only available after the process of blending has been completed. The thesis describes an implementation of a Raman spectroscopic method, which is novel in the given context, since it allows monitoring and control of the blending process online, in real time. A Raman spectrometer was designed, using a solid state laser for excitation (785 nm, 800 mW), a blazed grating for the diffraction (600 lines-per-millimeter, 750 nm blaze, 635

  1. Mineralogical and Raman spectroscopy studies of natural olivines exposed to different planetary environments

    NASA Astrophysics Data System (ADS)

    Weber, I.; Böttger, U.; Pavlov, S. G.; Jessberger, E. K.; Hübers, H.-W.

    2014-12-01

    New lander missions to bodies of our solar system are coming up and thus new techniques are desirable for the in-situ investigation of planetary surface and near surface materials. During the last decade Raman spectroscopy has been developed to become an excellent laboratory tool for fast petrological and mineralogical investigation of terrestrial and extraterrestrial rocks. Consequently, Raman spectroscopy has successfully been proposed for operation on planetary surfaces. In the joint ESA and Roscosmos mission ExoMars a Raman Laser Spectrometer (RLS) will for the first time be applied in space to identify minerals and organic compounds in Martian surface rocks and soils. The present study aims to investigate the possible response of various environmental conditions to Raman spectra in preparation for the ExoMars mission, as well as other space missions in future. For our study we selected five natural olivines with different forsterite (Mg2SiO4) and fayalite (Fe2SiO4) compositions. Olivine as an important rock forming mineral of the Earth upper mantle and an abundant mineral in Martian meteorites is one of the key planetary mineral. The spectra were taken in various environmental conditions that include vacuum down to 10-6 mbar, 8 mbar CO2 atmosphere, and temperatures ranging between room temperature and~8 K resembling those on Mars as well as on the Moon and on asteroids. We have found that forsterite shows only small temperature-related shifts in Raman spectra at very low temperatures indicating relatively weak changes in the lattice modes. Fayalite demonstrates, in addition to temperature dependent changes in the lattice modes found for forsterite, modification of Raman spectra at low Stokes frequencies. This is an effect in the SiO4 internal modes that most probably is caused by the high amount of iron in the mineral structure, which triggers antiferromagnetic transition at low temperatures. No influence of a CO2 atmosphere on Raman spectra for the

  2. Femtosecond stimulated Raman spectroscopy as a tool to detect molecular vibrations in ground and excited electronic states.

    PubMed

    Gelin, Maxim F; Domcke, Wolfgang; Rao, B Jayachander

    2016-05-14

    We give a detailed theoretical analysis of the simplest variant of femtosecond stimulated Raman spectroscopy, where a picosecond Raman pump pulse and a femtosecond Raman probe pulse are applied resonantly to a chromophore in thermal equilibrium in the ground electronic state. We demonstrate that this technique is capable of the detection of dephasing-free Raman-like lines revealing vibrational modes not only in the electronic ground state but also in the excited electronic state of the chromophore. The analytical results obtained with simplifying assumptions for the shape of the laser pulses are substantiated by numerical simulations with realistic laser pulses, employing the equation-of-motion phase-matching approach. PMID:27179484

  3. Diagnostic segregation of human brain tumours using Fourier-transform infrared and/or Raman spectroscopy coupled with discriminant analysis†

    PubMed Central

    Gajjar, Ketan; Heppenstall, Lara D.; Pang, Weiyi; Ashton, Katherine M.; Trevisan, Júlio; Patel, Imran I.; Llabjani, Valon; Stringfellow, Helen F.; Martin-Hirsch, Pierre L.; Dawson, Timothy; Martin, Francis L.

    2013-01-01

    The most common initial treatment received by patients with a brain tumour is surgical removal of the growth. Precise histopathological diagnosis of brain tumours is to some extent subjective. Furthermore, currently available diagnostic imaging techniques to delineate the excision border during cytoreductive surgery lack the required spatial precision to aid surgeons. We set out to determine whether infrared (IR) and/or Raman spectroscopy combined with multivariate analysis could be applied to discriminate between normal brain tissue and different tumour types (meningioma, glioma and brain metastasis) based on the unique spectral “fingerprints” of their biochemical composition. Formalin-fixed paraffin-embedded tissue blocks of normal brain and different brain tumours were de-waxed, mounted on low-E slides and desiccated before being analyzed using attenuated total reflection Fourier-transform IR (ATR-FTIR) and Raman spectroscopy. ATR-FTIR spectroscopy showed a clear segregation between normal and different tumour subtypes. Discrimination of tumour classes was also apparent with Raman spectroscopy. Further analysis of spectral data revealed changes in brain biochemical structure associated with different tumours. Decreased tentatively-assigned lipid-to-protein ratio was associated with increased tumour progression. Alteration in cholesterol esters-to-phenylalanine ratio was evident in grade IV glioma and metastatic tumours. The current study indicates that IR and/or Raman spectroscopy have the potential to provide a novel diagnostic approach in the accurate diagnosis of brain tumours and have potential for application in intra-operative diagnosis. PMID:24098310

  4. [Determination of Gasoline Composition Based on Raman Spectroscopy].

    PubMed

    Zhang, Bing; Deng, Zhi-yin; Zheng, Jing-kui; Wang, Xiao-ping

    2015-06-01

    For the purpose of the rapid prediction of every composition in gasoline, the Raman spectra of the gasoline brand 93 and 97, a batch of one-one mixtures with aromatic, olefin, ben, methanol and ethanol with different ratios are measured, 410 mixture samples were measured totally in this research. The obtained Raman spectra were preprocessed by a series of processing, they were data smoothing, baseline deduction and spectral normalized, etc. After that 33 characteristic peaks were extracted to be the eigenvalues for the whole Raman spectra. According to the current national standard test method, the values of every composition were measured by the gas chromatography. By using the eigenvalues as inputs, and actual contents of aromatic, olefin, ben, methanol and ethanol got from gas chromatography as outputs, two mathematical models of multi-output least squares support vector regression and partial least squares combination with multiple regression analysis were established to predict the values of the above compositions of a sample, respectively. The predicting results were compared with the values calculated from the gas chromatography measurement results and the mixture proportions, the multi-output least squares support vector regression has a better effects, and the obtained root mean square error of prediction for aromatic, olefin, ben, methanol and ethanol are 0.27%, 0.27%, 0.22%, 0.17%, 0.14%; the correlation coefficients are 0.999 3, 0.998 5, 0.998 6, 0.992 3, 0.993 5, respectively. This model is also applied to the detection of the unknown sample, the root mean square error of the prediction for the results does not exceed 0.5%, which can achieve the measurement requirements in the industry. Results show that the Raman spectra analysis technology based on multi-output least squares support vector regression can be a precise, fast and convenient new method for gasoline composition detection, and can be applied to the quality control of the gasoline

  5. Electronically tunable coherent Raman spectroscopy using acousto-optics tunable filter.

    PubMed

    Petrov, Georgi I; Meng, Zhaokai; Yakovlev, Vladislav V

    2015-09-21

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, we demonstrated a novel instrumentation to the broadband coherent Raman spectroscopy. System's tunability allows assessing Raman transitions ranging from <400 cm(-1) to 4500 cm(-1). We validated the use of the new instrumentation by collecting coherent anti-Stokes spectra and stimulated Raman spectra of various samples. PMID:26406668

  6. Shell-isolated nanoparticle-enhanced Raman spectroscopy: principle and applications (Presentation Recording)

    NASA Astrophysics Data System (ADS)

    Li, Jian-Feng; Tian, Zhong-Qun

    2015-08-01

    Surface-enhanced Raman spectroscopy (SERS) is a powerful technique that yields fingerprint vibrational information with ultra-high sensitivity. However, only roughened Ag, Au and Cu surfaces can generate strong SERS effect. The lack of materials and morphology generality has severely limited the breadth of SERS practical applications on surface science, electrochemistry and catalysis. Shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) was therefore invented to break the long-standing limitation of SERS. In SHINERS, Au@SiO2 core-shell nanoparticles were rationally designed. The gold core acts as plasmonic antenna and encapsulated by an ultra-thin, uniform and pinhole-free silica shell, can provide high electromagnetic field to enhance the Raman signals of probed molecules. The inert silica shell acts as tunneling barrier prevents the core from interacting with the environment. SHINERS has already been applied to a number of challenging systems, such as hydrogen and CO on Pt(hkl) and Rh(hkl), which can't be realized by traditional SERS. Combining with electrochemical methods, we has investigated the adsorption processes of pyridine at the Au(hkl) single crystal/solution interface, and in-situ monitored the surface electro-oxidation at Au(hkl) electrodes. These pioneering studies demonstrate convincingly the ability of SHINERS in exploring correlations between structure and reactivity as well as in monitoring intermediates at the interfaces. SHINERS was also explored from semiconductor surface for industry, to living bacteria for life science, and to pesticide residue detection for food safety. The concept of shell-isolated nanoparticle-enhancement is being applied to other spectroscopies such as infrared absorption, sum frequency generation and fluorescence. Jian-Feng Li et al., Nature, 2010, 464, 392-395.

  7. Femtosecond Stimulated Raman Spectroscopy by Six-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Moran, Andrew

    2015-03-01

    Knowledge of the structural changes that accompany photochemical reactions has motivated the development of a wide variety of time-resolved vibrational spectroscopies. For example, a technique known as femtosecond stimulated Raman spectroscopy (FSRS) has yielded important insights into numerous photochemical processes in the past 10-15 years. Simultaneous probing of all resonances in the fingerprint region of the vibrational spectrum and sensitivity to dynamics on the 100-fs time scale are the primary selling points for the FSRS technique. Despite its utility, FSRS is challenged by a large background of residual laser light and lower-order nonlinearities. In this talk, I will introduce a newly developed FSRS experiment in which five laser beams are used eliminate the background of residual laser light and lower-order nonlinearities present in the traditional three-beam FSRS geometry. Applications to photodissociation reactions in triiodide and heme proteins will be discussed. It is envisioned that this approach will be useful for investigating photoinduced dynamics in a wide variety of condensed phase systems.

  8. Fiber-coupled laser-induced breakdown and Raman spectroscopy for flexible sample characterization with depth profiling capabilities

    NASA Astrophysics Data System (ADS)

    Glaus, Reto; Hahn, David W.

    2014-10-01

    A combined laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy system for depth profile analyses is presented. The system incorporates a single 532 nm laser source, which is delivered through an optical fiber to the sample site. The homogenized laser beam results in well-defined cylindrical craters with diameters of 100 μm. LIBS depth profiling analyses of metals was performed applying pulse energies of about 1 mJ. The application of up to 500 pulses allowed to drill through layers of several tens of microns, while observing sharp transitions at the layer interfaces. The capability of the system for Raman spectroscopy was investigated for various polymer samples by reducing the pulse energies below the respective ablation threshold. A combined Raman/LIBS depth profiling was applied to a polymer-coated metal. Additionally, the capability of the system for calibration-free LIBS quantification (CF-LIBS) was evaluated. Quantification of major elements in metallic reference materials showed good agreement with the certified values with relative deviations of less than 30%. Finally, the optimized system was applied for depth profiling and elemental composition analysis of ancient Roman bronze rings. Overall, the presented setup combines the high flexibility of a fiber-coupled system with Raman and micro-LIBS, making the system interesting for depth profiling and elemental quantification in archaeometric as well as industrial applications.

  9. Exploring type II microcalcifications in benign and premalignant breast lesions by shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS)

    NASA Astrophysics Data System (ADS)

    Liang, Lijia; Zheng, Chao; Zhang, Haipeng; Xu, Shuping; Zhang, Zhe; Hu, Chengxu; Bi, Lirong; Fan, Zhimin; Han, Bing; Xu, Weiqing

    2014-11-01

    The characteristics of type II microcalcifications in fibroadenoma (FB), atypical ductal hyperplasia (ADH), and ductal carcinoma in situ (DCIS) breast tissues has been analyzed by the fingerprint features of Raman spectroscopy. Fresh breast tissues were first handled to frozen sections and then they were measured by normal Raman spectroscopy. Due to inherently low sensitivity of Raman scattering, Au@SiO2 shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) technique was utilized. A total number of 71 Raman spectra and 70 SHINERS spectra were obtained from the microcalcifications in benign and premalignant breast tissues. Principal component analysis (PCA) was used to distinguish the type II microcalcifications between these tissues. This is the first time to detect type II microcalcifications in premalignant (ADH and DCIS) breast tissue frozen sections, and also the first time SHINERS has been utilized for breast cancer detection. Conclusions demonstrated in this paper confirm that SHINERS has great potentials to be applied to the identification of breast lesions as an auxiliary method to mammography in the early diagnosis of breast cancer.

  10. Raman Spectroscopy as a Potential Tool for Detection of Brucella spp. in Milk

    PubMed Central

    Meisel, Susann; Stöckel, Stephan; Elschner, Mandy; Melzer, Falk; Popp, Jürgen

    2012-01-01

    Detection of Brucella, causing brucellosis, is very challenging, since the applied techniques are mostly time-demanding and not standardized. While the common detection system relies on the cultivation of the bacteria, further classical typing up to the biotype level is mostly based on phenotypic or genotypic characteristics. The results of genotyping do not always fit the existing taxonomy, and misidentifications between genetically closely related genera cannot be avoided. This situation gets even worse, when detection from complex matrices, such as milk, is necessary. For these reasons, the availability of a method that allows early and reliable identification of possible Brucella isolates for both clinical and epidemiological reasons would be extremely useful. We evaluated micro-Raman spectroscopy in combination with chemometric analysis to identify Brucella from agar plates and directly from milk: prior to these studies, the samples were inactivated via formaldehyde treatment to ensure a higher working safety. The single-cell Raman spectra of different Brucella, Escherichia, Ochrobactrum, Pseudomonas, and Yersinia spp. were measured to create two independent databases for detection in media and milk. Identification accuracies of 92% for Brucella from medium and 94% for Brucella from milk were obtained while analyzing the single-cell Raman spectra via support vector machine. Even the identification of the other genera yielded sufficient results, with accuracies of >90%. In summary, micro-Raman spectroscopy is a promising alternative for detecting Brucella. The measurements we performed at the single-cell level thus allow fast identification within a few hours without a demanding process for sample preparation. PMID:22660699

  11. Microstructure and defects probed by Raman spectroscopy in lithium niobate crystals and devices

    SciTech Connect

    Fontana, Marc D.; Bourson, Patrice

    2015-12-15

    Raman microprobe applied on LiNbO{sub 3} (LN) crystals and derived materials or devices is shown to be a tool to detect either local variations or changes of the whole structure. Position, width, or intensity of one Raman line can be used as markers of a structural change. Indeed, each Raman line can be assigned to a peculiar ionic motion and is differently sensitive to application of strain, temperature change, and electric field. Some vibrational modes are especially associated to the site of Li ion, or Nb ion, or still oxygen octahedron, so that they can be affected by the introduction of dopant ion on one or another site. Therefore, Raman Spectroscopy (RS) can be used as a site spectroscopy to describe the mechanism of doping incorporation in the LN lattice, allowing the optimization of some linear and non-linear optical properties according to the dopant concentration and substitution site. The composition or the content of non-stoichiometry related defects could be derived from the width of some lines. Any damage or local disorder can be detected by a line broadening. The quality or preservation of the structure after chemical treatment, or laser pulses, can be thus checked. The structure of ion-implanted or proton-exchanged wave-guides and periodically poled lithium niobate as well can be imaged from frequency shift or intensity change of some lines. RS is thus a useful way to control the structure of LN and/or to optimize the preparation parameters and its properties.

  12. Raman spectroscopy as a potential tool for detection of Brucella spp. in milk.

    PubMed

    Meisel, Susann; Stöckel, Stephan; Elschner, Mandy; Melzer, Falk; Rösch, Petra; Popp, Jürgen

    2012-08-01

    Detection of Brucella, causing brucellosis, is very challenging, since the applied techniques are mostly time-demanding and not standardized. While the common detection system relies on the cultivation of the bacteria, further classical typing up to the biotype level is mostly based on phenotypic or genotypic characteristics. The results of genotyping do not always fit the existing taxonomy, and misidentifications between genetically closely related genera cannot be avoided. This situation gets even worse, when detection from complex matrices, such as milk, is necessary. For these reasons, the availability of a method that allows early and reliable identification of possible Brucella isolates for both clinical and epidemiological reasons would be extremely useful. We evaluated micro-Raman spectroscopy in combination with chemometric analysis to identify Brucella from agar plates and directly from milk: prior to these studies, the samples were inactivated via formaldehyde treatment to ensure a higher working safety. The single-cell Raman spectra of different Brucella, Escherichia, Ochrobactrum, Pseudomonas, and Yersinia spp. were measured to create two independent databases for detection in media and milk. Identification accuracies of 92% for Brucella from medium and 94% for Brucella from milk were obtained while analyzing the single-cell Raman spectra via support vector machine. Even the identification of the other genera yielded sufficient results, with accuracies of >90%. In summary, micro-Raman spectroscopy is a promising alternative for detecting Brucella. The measurements we performed at the single-cell level thus allow fast identification within a few hours without a demanding process for sample preparation. PMID:22660699

  13. Multispectral diode laser based shifted excitation Raman difference spectroscopy for biological sample identification

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

    2012-06-01

    Raman spectroscopy is a well established analytical method with applications in many areas, e.g. analysis of biological samples. To overcome the problem of an undesired fluorescence background masking the Raman signals we present a multi-spectral approach using shifted excitation Raman difference spectroscopy (SERDS). For our investigations we applied microsystem diode lasers which realize two slightly shifted excitation wavelengths required to perform SERDS at 488 nm, 671 nm, and 785 nm. The emission at 488 nm with an optical power of up to 30 mW and a spectral shift of 0.3 nm (12 cm-1) is realized by frequency doubling of a 976 nm distributed feedback (DFB) diode laser. The 671 nm laser diode contains two separate laser cavities (spectral shift: 0.7 nm (13 cm-1)) each incorporating a volume Bragg grating as frequency selective element. In that case, optical powers up to 50 mW can be obtained. For investigations at 785 nm we used a DFB laser with a maximum optical power of 110 mW and a spectral shift of 0.5 nm (7 cm-1). Meat, fat tissue, connective tissue and bones from pork and beef were used as test samples to demonstrate the effective background removal using SERDS. For all three wavelengths integration times of only 5 - 10 seconds were necessary showing the possibility of SERDS for rapid sample identification. A comparison with conventional Raman spectra is given pointing out the improvement of spectral quality. The applicability of SERDS for other analytical applications, e.g. medical diagnosis will be discussed.

  14. Coherent Raman spectroscopy: From statics to dynamics and kinetics, progress in nonlinear methods

    NASA Astrophysics Data System (ADS)

    Akhmanov, S. A.

    1987-12-01

    In spite of its 60-year history Raman spectroscopy is still progressing nowadays. Highly stable lasers and short pulse oscillators, perfect electronic data acquisition systems, new nonlinear optical approaches created new exciting perspectives for Raman spectroscopy. One of the most important tendencies is Raman spectroscopy application for studying nonequilibrium states, fast dynamics and kinetics of atoms, molecules and condensed matter. All these problems were until recently regarded as inaccessible for optical spectroscopy. Nonlinear optical techniques of Coherent Anti-Stokes Raman Scattering (CARS) and modulation spectroscopy appeared to be most effective and provided important real-time information on molecular excitation and dissociation dynamics, deep cooling of molecules in a supersonic jet, short laser pulse induced phase transitions at semiconductor interface and so on. Problems yet to be solved include direct measurement of intramolecular vibrational relaxation, conformations in biomolecules, optical “oscilloscopy” of molecular vibrations.

  15. Combined fiber probe for fluorescence lifetime and Raman spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Dochow, Sebastian; Ma, Dinglong; Latka, Ines; Bocklitz, Thomas; Hartl, Brad; Bec, Julien; Fatakdawala, Hussain; Wachsmann-Hogiu, Sebastian; Marple, Eric; Urmey, Kirk; Schmitt, Michael; Marcu, Laura; Popp, Jürgen

    2016-03-01

    Raman spectroscopy has been proven to have tremendous potential as biomedical analytical tool for spectroscopic disease diagnostics. The use of fiberoptic coupled Raman spectroscopy systems can enable in-vivo characterization of suspicious lesions. However, Raman spectroscopy has the drawback of rather long acquisition times of several hundreds of milliseconds which makes scanning of larger regions quite challenging. By combining Raman spectroscopy with a fast imaging technique this problem can be alleviate in part. Fluorescence lifetime imaging (FLIm) offers a great potential for such a combination. FLIm can allow for fast tissue area pre-segmentation and location of the points for Raman spectra acquisition. Here, we introduce an optical fiber probe combining FLIm and Raman spectroscopy with an outer diameter of 2 mm. Fluorescence is generated via excitation with a fiber laser at 355 nm. The fluorescence emission is spectrally resolved using a custom-made wavelength-selection module (WSM). The Raman excitation power at 785 nm was set to 50 mW for the in-vivo measurements to prevent sample drying. The lateral probe resolution was determined to be <250 μm for both modalities. This value was taken as step size for several raster scans of different tissue types which were conducted to show the overlap of both modalities under realistic conditions. Finally the probe was used for in vivo raster scans of a rat's brain and subsequently to acquire FLIm guided Raman spectra of several tissues in and around the craniotomy.

  16. Simultaneous fingerprint and high-wavenumber fiber-optic Raman spectroscopy improves in vivo diagnosis of esophageal squamous cell carcinoma at endoscopy

    PubMed Central

    Wang, Jianfeng; Lin, Kan; Zheng, Wei; Yu Ho, Khek; Teh, Ming; Guan Yeoh, Khay; Huang, Zhiwei

    2015-01-01

    This work aims to evaluate clinical value of a fiber-optic Raman spectroscopy technique developed for in vivo diagnosis of esophageal squamous cell carcinoma (ESCC) during clinical endoscopy. We have developed a rapid fiber-optic Raman endoscopic system capable of simultaneously acquiring both fingerprint (FP)(800–1800 cm−1) and high-wavenumber (HW)(2800–3600 cm−1) Raman spectra from esophageal tissue in vivo. A total of 1172 in vivo FP/HW Raman spectra were acquired from 48 esophageal patients undergoing endoscopic examination. The total Raman dataset was split into two parts: 80% for training; while 20% for testing. Partial least squares-discriminant analysis (PLS-DA) and leave-one patient-out, cross validation (LOPCV) were implemented on training dataset to develop diagnostic algorithms for tissue classification. PLS-DA-LOPCV shows that simultaneous FP/HW Raman spectroscopy on training dataset provides a diagnostic sensitivity of 97.0% and specificity of 97.4% for ESCC classification. Further, the diagnostic algorithm applied to the independent testing dataset based on simultaneous FP/HW Raman technique gives a predictive diagnostic sensitivity of 92.7% and specificity of 93.6% for ESCC identification, which is superior to either FP or HW Raman technique alone. This work demonstrates that the simultaneous FP/HW fiber-optic Raman spectroscopy technique improves real-time in vivo diagnosis of esophageal neoplasia at endoscopy. PMID:26243571

  17. Simultaneous fingerprint and high-wavenumber fiber-optic Raman spectroscopy improves in vivo diagnosis of esophageal squamous cell carcinoma at endoscopy

    NASA Astrophysics Data System (ADS)

    Wang, Jianfeng; Lin, Kan; Zheng, Wei; Yu Ho, Khek; Teh, Ming; Guan Yeoh, Khay; Huang, Zhiwei

    2015-08-01

    This work aims to evaluate clinical value of a fiber-optic Raman spectroscopy technique developed for in vivo diagnosis of esophageal squamous cell carcinoma (ESCC) during clinical endoscopy. We have developed a rapid fiber-optic Raman endoscopic system capable of simultaneously acquiring both fingerprint (FP)(800-1800 cm-1) and high-wavenumber (HW)(2800-3600 cm-1) Raman spectra from esophageal tissue in vivo. A total of 1172 in vivo FP/HW Raman spectra were acquired from 48 esophageal patients undergoing endoscopic examination. The total Raman dataset was split into two parts: 80% for training; while 20% for testing. Partial least squares-discriminant analysis (PLS-DA) and leave-one patient-out, cross validation (LOPCV) were implemented on training dataset to develop diagnostic algorithms for tissue classification. PLS-DA-LOPCV shows that simultaneous FP/HW Raman spectroscopy on training dataset provides a diagnostic sensitivity of 97.0% and specificity of 97.4% for ESCC classification. Further, the diagnostic algorithm applied to the independent testing dataset based on simultaneous FP/HW Raman technique gives a predictive diagnostic sensitivity of 92.7% and specificity of 93.6% for ESCC identification, which is superior to either FP or HW Raman technique alone. This work demonstrates that the simultaneous FP/HW fiber-optic Raman spectroscopy technique improves real-time in vivo diagnosis of esophageal neoplasia at endoscopy.

  18. Recent advances in laser tweezers Raman spectroscopy (LTRS) for label-free analysis of single cells.

    PubMed

    Chan, James W

    2013-01-01

    Laser tweezers Raman spectroscopy (LTRS), a technique that integrates optical tweezers with confocal Raman spectroscopy, is a variation of micro-Raman spectroscopy that enables the manipulation and biochemical analysis of single biological particles in suspension. This article provides an overview of the LTRS method, with an emphasis on highlighting recent advances over the past several years in the development of the technology and several new biological and biomedical applications that have been demonstrated. A perspective on the future developments of this powerful cytometric technology will also be presented. PMID:23175434

  19. Analysis of Individual Cells and Endospores by Micro-Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Esposito, Anthony; Huser, Thomas; Talley, Chad; Hollars, Christopher; Balhorn, Rod; Lane, Stephen

    2003-03-01

    We have collected Raman spectra of individual sperm cells by confocal micro-Raman spectroscopy. The high spatial resolution of this technique allows for compositional analysis of different sections of the sperm cells. The relative intensities of protein and DNA Raman transitions allow one to define a protein-DNA ratio. We have also collected the Raman spectra of individual bacterial endospores from four species in the genus Bacillus. The spectra were generally dominated by scattering from calcium dipicolinate, although scattering assignable to protein bands was also observed. A small fraction of the spores did not exhibit Raman scattering from CaDPA, possibly due to incomplete sporulation. These examples demonstrate the applicability of micro-Raman spectroscopy as a non-invasive method for addressing variability in the composition of cells.* *This work was performed under the auspices of the U.S. Department of Energy by the University of California, Lawrence Livermore National Laboratory under contract number W-7405-Eng-48.

  20. Characterization of polysilicon films by Raman spectroscopy and transmission electron microscopy: A comparative study

    SciTech Connect

    Tallant, D.R.; Headley, T.J.; Medernach, J.W.; Geyling, F.

    1993-11-12

    Samples of chemically-vapor-deposited micrometer and sub-micrometer-thick films of polysilicon were analyzed by transmission electron microscopy (TEM) in cross-section and by Raman spectroscopy with illumination at their surface. TEM and Raman spectroscopy both find varying amounts of polycrystalline and amorphous silicon in the wafers. Raman spectra obtained using blue, green and red excitation wavelengths to vary the Raman sampling depth are compared with TEM cross-sections of these films. Films showing crystalline columnar structures in their TEM micrographs have Raman spectra with a band near 497 cm{sup {minus}1} in addition to the dominant polycrystalline silicon band (521 cm{sup {minus}1}). The TEM micrographs of these films have numerous faulted regions and fringes indicative of nanometer-scale silicon structures, which are believed to correspond to the 497cm{sup {minus}1} Raman band.