Sample records for anti-stokes raman spectroscopy

  1. Analysis of organic pollutant degradation in pulsed plasma by coherent anti-Stokes Raman spectroscopy

    International Nuclear Information System (INIS)

    Bratescu, Maria Antoneta; Hieda, Junko; Umemura, Tomonari; Saito, Nagahiro; Takai, Osamu


    The degradation of p-benzoquinone (p-BQ) in water was investigated by the coherent anti-Stokes Raman spectroscopy (CARS) method, in which the change of the anti-Stokes signal intensity corresponding to the vibrational transitions of the molecule is monitored during and after solution plasma processing (SPP). In the beginning of SPP treatment, the CARS signal intensity of the ring vibrational molecular transitions at 1233 and 1660 cm -1 increases under the influence of the electric field of the plasma, depending on the delay time between the plasma pulse and the laser firing pulse. At the same time, the plasma contributes to the degradation of p-BQ molecules by generating hydrogen and hydroxyl radicals, which decompose p-BQ into different carboxylic acids. After SPP, the CARS signal intensity of the vibrational bands of p-BQ ceased and the degradation of p-BQ was confirmed by UV-visible absorption spectroscopy and liquid chromatography analysis.

  2. Femtosecond Coherent Anti-Stokes Raman Spectroscopy (CARS) As Next Generation Nonlinear LIDAR Spectroscopy and Microscopy

    International Nuclear Information System (INIS)

    Ooi, C. H. Raymond


    Nonlinear spectroscopy using coherent anti-Stokes Raman scattering and femtosecond laser pulses has been successfully developed as powerful tools for chemical analysis and biological imaging. Recent developments show promising possibilities of incorporating CARS into LIDAR system for remote detection of molecular species in airborne particles. The corresponding theory is being developed to describe nonlinear scattering of a mesoscopic particle composed of complex molecules by laser pulses with arbitrary shape and spectral content. Microscopic many-body transform theory is used to compute the third order susceptibility for CARS in molecules with known absorption spectrum and vibrational modes. The theory is combined with an integral scattering formula and Mie-Lorentz formulae, giving a rigorous formalism which provides powerful numerical experimentation of CARS spectra, particularly on the variations with the laser parameters and the direction of detection.

  3. Width-Increased Dual-Pump Enhanced Coherent Anti-Stokes Raman Spectroscopy (WIDECARS) (United States)

    Tedder, Sarah A.; Danehy, Paul M.; Cutler, Andrew D.


    WIDECARS is a dual-pump coherent anti-Stokes Raman Spectroscopy technique that is capable of simultaneously measuring temperature and species mole fractions of N2, O2, H2, C2H4, CO, and CO2. WIDECARS is designed for measurements of all the major species (except water) in supersonic combustion flows fueled with hydrogen and hydrogen/ethylene mixtures. The two lowest rotational energy levels of hydrogen detectable by WIDECARS are H2 S(3) and H2 S(4). The detection of these lines gives the system the capability to measure temperature and species concentrations in regions of the flow containing pure hydrogen fuel at room temperature.

  4. Study of high-temperature multiplex HCl coherent anti-Stokes Raman spectroscopy spectra. (United States)

    Singh, J P; Yueh, F Y; Kao, W; Cook, R L


    A feasibility study of temperature measurement with multiplex HCl coherent anti-Stokes Raman spectroscopy (CARS) is investigated. The HCl CARS spectra of a 100% HCl gas sample are recorded in a quartz sample cell placed in a furnace at 1 atm pressure and at different temperatures. The nonlinear susceptibility of HCl (chi(nr)(HCl)), which is measured with the present CARS experimental setup, is reported. The experimental spectra are fit by using a library of simulated HCl CARS spectra with a least-squares-fitting program to infer the temperature. The inferred temperatures from HCl CARS spectra are in agreement with thermocouple temperatures.

  5. Diagnostics of silane and germane radio frequency plasmas by coherent anti-Stokes Raman spectroscopy (United States)

    Perry, Joseph W.; Shing, Y. H.; Allevato, C. E.


    In situ plasma diagnostics using coherent anti-Stokes Raman spectroscopy have shown different dissociation characteristics for GeH4 and SiH4 in radio frequency (rf) plasma-enhanced chemical vapor deposition of amorphous silicon germanium alloy (a-SiGe:H) thin films. The GeH4 dissociation rate in rf plasmas is a factor of about 3 larger than that of SiH4. Plasma diagnostics have revealed that the hydrogen dilution of the SiH4 and GeH4 mixed plasma plays a critical role in suppressing the gas phase polymerization and enhancing the GeH4 dissociation.

  6. Next generation hazard detection via ultrafast coherent anti-Stokes Raman spectroscopy (United States)

    Brady, John J.; Pellegrino, Paul M.


    Multiplex coherent anti-Stokes Raman spectroscopy (MCARS) is used to detect an explosive precursor material and two chemical warfare simulants. The spectral bandwidth of the femtosecond laser pulse used in these studies is sufficient to coherently and simultaneously drive all the vibrational modes in the molecule of interest. The research performed here demonstrates that MCARS has the capability to detect an explosive precursor (e.g., acetone) and hazardous materials, such as dimethyl methylphosphonate and 2-chloroethyl methyl sulfide (a sarin and a mustard gas chemical warfare simulant, respectively), with high specificity. Evidence shows that MCARS is capable of overcoming common the sensitivity limitations of spontaneous Raman scattering, thus allowing for the detection of the target material in milliseconds with standard USB spectrometers as opposed to seconds with intensified spectrometers. The exponential increase in the number of scattered photons suggests that the MCARS technique may be capable of overcoming range detection challenges common to spontaneous Raman scattering.

  7. Raman optical activity spectroscopy by visible-excited coherent anti-Stokes Raman scattering. (United States)

    Hiramatsu, Kotaro; Leproux, Philippe; Couderc, Vincent; Nagata, Takashi; Kano, Hideaki


    We developed a Raman optical activity (ROA) spectroscopic system with visible-excited coherent anti-Stokes Raman scattering (CARS). A supercontinuum within the visible region was generated with a photonic crystal fiber pumped with both 532 and 1064 nm excitation, generating a multiplexed CARS-ROA spectrum covering the whole fingerprint region. In visible excitation, the CARS-ROA spectrum of (-)-β-pinene shows a higher contrast ratio of the chirality-induced signal to the achiral background than that of the previously reported near-infrared CARS-ROA spectrum.

  8. Broadband coherent anti-Stokes Raman spectroscopy with a modeless dye laser. (United States)

    Hahn, J W; Park, C W; Park, S N


    We develop a modeless dye laser for broadband coherent anti-Stokes Raman spectroscopy (CARS) and investigate the operational characteristics of the modeless laser. The energy efficiency of the modeless laser is 6%, and the beam divergence is 0.65 mrad. We construct a compact movable CARS system with the modeless laser and a graphite tube furnace to assess the accuracy of the CARS temperature. It is found that the difference between the averaged CARS temperature and the radiation temperature measured with an optical pyrometer is <2% at a temperature range from 1000 to 2400 K. We also measure the averaged CARS temperature drift owing to the variation of the spectral distribution of the modeless laser, which is <1.5% during 5 h of operation.

  9. Rapid-scan Fourier-transform coherent anti-Stokes Raman scattering spectroscopy with heterodyne detection. (United States)

    Hiramatsu, Kotaro; Luo, Yizhi; Ideguchi, Takuro; Goda, Keisuke


    High-speed Raman spectroscopy has become increasingly important for analyzing chemical dynamics in real time. To address the need, rapid-scan Fourier-transform coherent anti-Stokes Raman scattering (FT-CARS) spectroscopy has been developed to realize broadband CARS measurements at a scan rate of more than 20,000 scans/s. However, the detection sensitivity of FT-CARS spectroscopy is inherently low due to the limited number of photons detected during each scan. In this Letter, we show our experimental demonstration of enhanced sensitivity in rapid-scan FT-CARS spectroscopy by heterodyne detection. Specifically, we implemented heterodyne detection by superposing the CARS electric field with an external local oscillator (LO) for their interference. The CARS signal was amplified by simply increasing the power of the LO without the need for increasing the incident power onto the sample. Consequently, we achieved enhancement in signal intensity and the signal-to-noise ratio by factors of 39 and 5, respectively, compared to FT-CARS spectroscopy with homodyne detection. The sensitivity-improved rapid-scan FT-CARS spectroscopy is expected to enable the sensitive real-time observation of chemical dynamics in a broad range of settings, such as combustion engines and live biological cells.

  10. Coherent anti-Stokes Raman spectroscopy temperature measurements in an internal combustion engine (United States)

    Ball, Don; Driver, H. Steve T.; Hutcheon, Richard J.; Lockett, Russel J.; Robertson, Gerald N.


    Part of a project to investigate the physics and chemistry of alternative fuels in internal combustion engines is reported. Coherent anti-Stokes Raman spectroscopy (CARS) is used to probe the fuel-air mixture in the cylinder of a Richardo E6 variable compression ratio research engine. The laser system comprises a passively Q- switched single-longitudinal-mode frequency-doubled Nd:YAG laser and a broadband dye laser, both with a pulse length of 15 ns. A crankshaft encoder and electronic delay are used to fire the lasers at specified times during the engine cycle, and CARS spectra are acquired using a 0.75 m spectrometer and a 1024 optical multichannel analyzer. Because of the uncertainties associated with collisional narrowing in the theoretical modeling of high-pressure CARS spectra, temperatures are determined by comparing the engine spectra with a library of experimental CARS spectra from a calibrated high-pressure, high- temperature cell. This purely experimental technique is shown to be superior to two theoretical models under the considered conditions, giving temperatures during the compression stroke of the engine with standard deviations of typically 10 K and a possible systematic error of 15 K. Together with pressure records, this information is used as input data for chemical kinetic modeling of the combustion process.

  11. Nonequilibrium Supersonic Freestream Studied Using Coherent Anti-Stokes Raman Spectroscopy (United States)

    Cutler, Andrew D.; Cantu, Luca M.; Gallo, Emanuela C. A.; Baurle, Rob; Danehy, Paul M.; Rockwell, Robert; Goyne, Christopher; McDaniel, Jim


    Measurements were conducted at the University of Virginia Supersonic Combustion Facility of the flow in a constant-area duct downstream of a Mach 2 nozzle. The airflow was heated to approximately 1200 K in the facility heater upstream of the nozzle. Dual-pump coherent anti-Stokes Raman spectroscopy was used to measure the rotational and vibrational temperatures of N2 and O2 at two planes in the duct. The expectation was that the vibrational temperature would be in equilibrium, because most scramjet facilities are vitiated air facilities and are in vibrational equilibrium. However, with a flow of clean air, the vibrational temperature of N2 along a streamline remains approximately constant between the measurement plane and the facility heater, the vibrational temperature of O2 in the duct is about 1000 K, and the rotational temperature is consistent with the isentropic flow. The measurements of N2 vibrational temperature enabled cross-stream nonuniformities in the temperature exiting the facility heater to be documented. The measurements are in agreement with computational fluid dynamics models employing separate lumped vibrational and translational/rotational temperatures. Measurements and computations are also reported for a few percent steam addition to the air. The effect of the steam is to bring the flow to thermal equilibrium, also in agreement with the computational fluid dynamics.

  12. Temperature Measurements in Reacting Flows Using Time-Resolved Femtosecond Coherent Anti-Stokes Raman Scattering (fs-CARS) Spectroscopy (Postprint)

    National Research Council Canada - National Science Library

    Roy, Sukesh; Kinnius, Paul J; Lucht, Robert P; Gord, James R


    Time-resolved femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy of the nitrogen molecule is used for the measurement of temperature in atmospheric-pressure, near-adiabatic, hydrogen-air diffusion flames...

  13. Pure-rotational H2thermometry by ultrabroadband coherent anti-Stokes Raman spectroscopy. (United States)

    Courtney, Trevor L; Bohlin, Alexis; Patterson, Brian D; Kliewer, Christopher J


    Coherent anti-Stokes Raman spectroscopy (CARS) is a sensitive technique for probing highly luminous flames in combustion applications to determine temperatures and species concentrations. CARS thermometry has been demonstrated for the vibrational Q-branch and pure-rotational S-branch of several small molecules. Practical advantages of pure-rotational CARS, such as multi-species detection, reduction of coherent line mixing and collisional narrowing even at high pressures, and the potential for more precise thermometry, have motivated experimental and theoretical advances in S-branch CARS of nitrogen (N 2 ), for example, which is a dominant species in air-fed combustion processes. Although hydrogen (H 2 ) is of interest given its prevalence as a reactant and product in many gas-phase reactions, laser bandwidth limitations have precluded the extension of CARS thermometry to the H 2 S-branch. We demonstrate H 2 thermometry using hybrid femtosecond/picosecond pure-rotational CARS, in which a broadband pump/Stokes pulse enables simultaneous excitation of the set of H 2 S-branch transitions populated at flame temperatures over the spectral region of 0-2200 cm -1 . We present a pure-rotational H 2 CARS spectral model for data fitting and compare extracted temperatures to those from simultaneously collected N 2 spectra in two systems of study: a heated flow and a diffusion flame on a Wolfhard-Parker slot burner. From 300 to 650 K in the heated flow, the H 2 and N 2 CARS extracted temperatures are, on average, within 2% of the set temperature. For flame measurements, the fitted H 2 and N 2 temperatures are, on average, within 5% of each other from 300 to 1600 K. Our results confirm the viability of pure-rotational H 2 CARS thermometry for probing combustion reactions.

  14. Two-beam ultrabroadband coherent anti-Stokes Raman spectroscopy for high resolution gas-phase multiplex imaging

    International Nuclear Information System (INIS)

    Bohlin, Alexis; Kliewer, Christopher J.


    We propose and develop a method for wideband coherent anti-Stokes Raman spectroscopy (CARS) in the gas phase and demonstrate the single-shot measurement of N 2 , H 2 , CO 2 , O 2 , and CH 4 . Pure-rotational and vibrational O-, Q-, and S- branch spectra are collected simultaneously, with high spectral and spatial resolution, and within a single-laser-shot. The relative intensity of the rotational and vibrational signals can be tuned arbitrarily using polarization techniques. The ultrashort 7 fs pump and Stokes pulses are automatically overlapped temporally and spatially using a two-beam CARS technique, and the crossed probe beam allows for excellent spatial sectioning of the probed location

  15. What are the intensities and line-shapes of the twenty four polarization terms in coherent anti-Stokes Raman spectroscopy?

    Energy Technology Data Exchange (ETDEWEB)

    Niu, Kai [School of Science, Tianjin University of Technology and Education, Tianjin, 300222 (China); Lee, Soo-Y., E-mail: [Division of Physics & Applied Physics, and Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)


    Coherent anti-Stokes Raman spectroscopy (CARS) is conventionally described by just one diagram/term where the three electric field interactions act on the ket side in a Feynman dual time-line diagram in a specific time order of pump, Stokes and probe pulses. In theory, however, any third-order nonlinear spectroscopy with three different electric fields interacting with a molecule can be described by forty eight diagrams/terms. They reduce to just 24 diagrams/terms if we treat the time ordering of the electric field interactions on the ket independently of those on the bra, i.e. the ket and bra wave packets evolve independently. The twenty four polarization terms can be calculated in the multidimensional, separable harmonic oscillator model to obtain the intensities and line-shapes. It is shown that in fs/ps CARS, for the two cases of off-resonance CARS in toluene and resonance CARS in rhodamine 6G, where we use a fs pump pulse, a fs Stokes pulse and a ps probe pulse, we obtain sharp vibrational lines in four of the polarization terms where the pump and Stokes pulses can create a vibrational coherence on the ground electronic state, while the spectral line-shapes of the other twenty terms are broad and featureless. The conventional CARS term with sharp vibrational lines is the dominant term, with intensity at least one order of magnitude larger than the other terms.

  16. What are the intensities and line-shapes of the twenty four polarization terms in coherent anti-Stokes Raman spectroscopy? (United States)

    Niu, Kai; Lee, Soo-Y.


    Coherent anti-Stokes Raman spectroscopy (CARS) is conventionally described by just one diagram/term where the three electric field interactions act on the ket side in a Feynman dual time-line diagram in a specific time order of pump, Stokes and probe pulses. In theory, however, any third-order nonlinear spectroscopy with three different electric fields interacting with a molecule can be described by forty eight diagrams/terms. They reduce to just 24 diagrams/terms if we treat the time ordering of the electric field interactions on the ket independently of those on the bra, i.e. the ket and bra wave packets evolve independently. The twenty four polarization terms can be calculated in the multidimensional, separable harmonic oscillator model to obtain the intensities and line-shapes. It is shown that in fs/ps CARS, for the two cases of off-resonance CARS in toluene and resonance CARS in rhodamine 6G, where we use a fs pump pulse, a fs Stokes pulse and a ps probe pulse, we obtain sharp vibrational lines in four of the polarization terms where the pump and Stokes pulses can create a vibrational coherence on the ground electronic state, while the spectral line-shapes of the other twenty terms are broad and featureless. The conventional CARS term with sharp vibrational lines is the dominant term, with intensity at least one order of magnitude larger than the other terms.

  17. What are the intensities and line-shapes of the twenty four polarization terms in coherent anti-Stokes Raman spectroscopy?

    International Nuclear Information System (INIS)

    Niu, Kai; Lee, Soo-Y.


    Coherent anti-Stokes Raman spectroscopy (CARS) is conventionally described by just one diagram/term where the three electric field interactions act on the ket side in a Feynman dual time-line diagram in a specific time order of pump, Stokes and probe pulses. In theory, however, any third-order nonlinear spectroscopy with three different electric fields interacting with a molecule can be described by forty eight diagrams/terms. They reduce to just 24 diagrams/terms if we treat the time ordering of the electric field interactions on the ket independently of those on the bra, i.e. the ket and bra wave packets evolve independently. The twenty four polarization terms can be calculated in the multidimensional, separable harmonic oscillator model to obtain the intensities and line-shapes. It is shown that in fs/ps CARS, for the two cases of off-resonance CARS in toluene and resonance CARS in rhodamine 6G, where we use a fs pump pulse, a fs Stokes pulse and a ps probe pulse, we obtain sharp vibrational lines in four of the polarization terms where the pump and Stokes pulses can create a vibrational coherence on the ground electronic state, while the spectral line-shapes of the other twenty terms are broad and featureless. The conventional CARS term with sharp vibrational lines is the dominant term, with intensity at least one order of magnitude larger than the other terms

  18. Resonant anti-Stokes Raman scattering in single-walled carbon nanotubes (United States)

    Gordeev, Georgy; Jorio, Ado; Kusch, Patryk; Vieira, Bruno G. M.; Flavel, Benjamin; Krupke, Ralph; Barros, Eduardo B.; Reich, Stephanie


    The dependence of the anti-Stokes Raman intensity on the excitation laser energy in carbon nanotubes is studied by resonant Raman spectroscopy. The complete resonant anti-Stokes and Stokes Raman profiles of the high-energy longitudinal phonon (G+) are obtained for (8,3), (7,5), (6,4), and (6,5) single chirality enriched samples. A high asymmetry between the intensity of the incoming and outgoing resonance is observed in the resonant Raman profiles. In contrast to Stokes scattering, anti-Stokes scattering is more intense at the outgoing resonance then at the incoming resonance. The resonance profiles are explained by a Raman process that includes the phonon-mediated interactions with the dark excitonic state. The chirality dependence of the Raman profiles is due to the variation in the exciton-phonon matrix elements, in agreement with tight-binding calculations. Based on the asymmetric Raman profiles we present the resonance factors for the Stokes/anti-Stokes ratios in carbon nanotubes.

  19. CARS (Coherent Anti-stokes Raman Spectroscopy) diagnostics of high pressure combustion. Final technical report 15 Feb 1979-30 Sep 1982

    Energy Technology Data Exchange (ETDEWEB)

    Stufflebeam, J.H.; Shirley, J.A.; Hall, R.J.


    Under Contract DAAG29-79-C-0008 sponsored by the Army Research Office, the United Technologies Research Center (UTRC) has conducted basic research investigations into coherent anti-Stokes Human spectroscopy (CARS). CARS is a remote laser diagnostic technique for temperature and species measurements in hostile combustion environments. As such it possesses considerable relevance to the Army in the general areas of ballistics, propulsion and internal combustion engines. This final report describes the results of the investigation which were conducted in two specific areas. The first area concerns the effects of high pressure, specifically the phenomenon of collisional narrowing, on CARS spectra from which temperature and density information device. Experimental studies of CARS spectra are conducted in N2 and CO2 in a heated, high pressure cell. The experimental spectra were in excellent agreement with the theoretical model developed to describe high pressure CARS spectroscopy.

  20. Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds. (United States)

    Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola


    Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp(3) vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.

  1. Investigation of enhanced forward and backward anti-stokes Raman signals in lithium niobate waveguides

    Energy Technology Data Exchange (ETDEWEB)

    Li, Da; Hong, Pengda; Ding, Yujie J., E-mail: [Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); Liu, Zhaojun; Wang, Lei [Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 (United States); School of Information Science and Engineering, Shandong University, Jinan, Shandong 250100 (China); Hua, Ping-Rang; Zhang, De-Long [School of Precision Instruments and Opto-electronics Engineering, Tianjin University, Tianjin 300072 (China)


    We have observed enhancements of the anti-Stokes Raman signals generated in lithium niobate waveguides in the forward and backward configurations by at least one order of magnitude under the pump power of the microwatt level. These output signals were measured using a single photon detector. The forward and backward propagating anti-Stokes signals exhibited different spectral features.

  2. Coherent anti-Stokes Raman spectroscopic measurement of air entrainment in argon plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Fincke, J.R.; Rodriquez, R.; Pentecost, C.G.


    The concentration and temperature of air entrained into an argon plasma jet has been measured using coherent anti-Stokes Raman spectroscopy (CARS). The flow field is characterized by a short region of well behaved laminar flow near the nozzle exit followed by an abrupt transition to turbulence. Once the transition to turbulence occurs, air is rapidly entrained into the jet core. The location of the transition region is thought to be driven by the rapid cooling of the jet and the resulting increase in Reynolds number. 8 refs., 6 figs.

  3. Coherent anti-Stokes Raman scattering (CARS) detection or hot atom reaction product internal energy distributions

    International Nuclear Information System (INIS)

    Quick, C.R. Jr.; Moore, D.S.


    Coherent anti-Stokes Raman spectroscopy (CARS) is being utilized to investigate the rovibrational energy distributions produced by reactive and nonreactive collisions of translationally hot atoms with simple molecules. Translationally hot H atoms are produced by ArF laser photolysis of HBr. Using CARS we have monitored, in a state-specific and time-resolved manner, rotational excitation of HBr (v = 0), vibrational excitation of HBr and H 2 , rovibrational excitation of H 2 produced by the reaction H + HBr → H 2 + Br, and Br atom production by photolysis of HBr

  4. Coherent anti-Stokes Raman scattering microscopy with a photonic crystal fiber based light source

    DEFF Research Database (Denmark)

    Paulsen, H.N.; Hilligsøe, Karen Marie; Thøgersen, J.


    A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup is demonstra......A coherent anti-Stokes Raman scattering microscope based on a Ti:sapphire femtosecond oscillator and a photonic crystal fiber is demonstrated. The nonlinear response of the fiber is used to generate the additional wavelength needed in the Raman process. The applicability of the setup...

  5. A note on two-phonon coherent anti-stokes Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Shen, Y. R. [Univ. of California, Berkeley, CA (United States). Dept. of Physics; Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Materials and Molecular Research Division


    Difference-frequency mixing of two pump waves can in principle excite two coherent phonon waves via the parametric process. Finally, only when the phonon excitation is small can the nonlinear susceptibility of two-phonon coherent anti-Stokes Raman scattering be described as proportional to the product of two Raman tensors.

  6. Epi-detection of vibrational phase contrast coherent anti-Stokes Raman scattering

    NARCIS (Netherlands)

    Garbacik, E.T.; Korterik, Jeroen P.; Otto, Cornelis; Herek, Jennifer Lynn; Offerhaus, Herman L.


    We demonstrate a system for the phase-resolved epi-detection of coherent anti-Stokes Raman scattering (CARS) signals in highly scattering and/or thick samples. With this setup, we measure the complex vibrational responses of multiple components in a thick, highly-scattering pharmaceutical tablet in

  7. Ground-state depletion for subdiffraction-limited spatial resolution in coherent anti-Stokes Raman

    NARCIS (Netherlands)

    Cleff, C.; Groß, P.; Fallnich, C.; Offerhaus, H. L.; Herek, J.; Kruse, K.; Beeker, W. P.; Lee, C. J.; Boller, K. J.


    We theoretically investigate ground-state depletion for subdiffraction-limited spatial resolution in coherent anti-Stokes Raman scattering (CARS) microscopy. We propose a scheme based on ground-state depopulation, which is achieved via a control laser light field incident prior to the CARS

  8. Rapid identification of heterogeneous mixture components with hyperspectral coherent anti-Stokes Raman scattering imaging

    NARCIS (Netherlands)

    Garbacik, E.T.; Herek, Jennifer Lynn; Otto, Cornelis; Offerhaus, Herman L.


    For the rapid analysis of complicated heterogeneous mixtures, we have developed a method to acquire and intuitively display hyperspectral coherent anti-Stokes Raman scattering (CARS) images. The imaging is performed with a conventional optical setup based around an optical parametric oscillator.

  9. Coherent anti-Stokes Raman scattering (CARS) microscopy driving the future of loaded mesoporous silica imaging

    NARCIS (Netherlands)

    Fussell, A.L.; Mah, Pei Ting; Offerhaus, Herman L.; Niemi, Sanna-Mari; Salonen, Jarno; Santos, Helder A.; Strachan, Clare


    This study reports the use of variants of coherent anti-Stokes Raman scattering (CARS) microscopy as a novel method for improved physicochemical characterization of drug-loaded silica particles. Ordered mesoporous silica is a biomaterial that can be loaded to carry a number of biochemicals,

  10. Supercontinuum generation for coherent anti- Stokes Raman scattering microscopy with photonic crystal fibers

    DEFF Research Database (Denmark)

    Pedersen, Pernille Klarskov; Isomäki, Antti; Hansen, Kim P.


    Photonic crystal fiber (PCF) designs with two zero-dispersion wavelengths (ZDWs) are experimentally investigated in order to suggest a novel PCF for coherent anti-Stokes Raman scattering (CARS) microscopy. From our investigation, we select the optimum PCF design and demonstrate a tailored spectru...

  11. Coherent anti-Stokes Raman scattering microscopy: overcoming technical barriers for clinical translation. (United States)

    Tu, Haohua; Boppart, Stephen A


    Clinical translation of coherent anti-Stokes Raman scattering microscopy is of great interest because of the advantages of noninvasive label-free imaging, high sensitivity, and chemical specificity. For this to happen, we have identified and review the technical barriers that must be overcome. Prior investigations have developed advanced techniques (features), each of which can be used to effectively overcome one particular technical barrier. However, the implementation of one or a small number of these advanced features in previous attempts for clinical translation has often introduced more tradeoffs than benefits. In this review, we outline a strategy that would integrate multiple advanced features to overcome all the technical barriers simultaneously, effectively reduce tradeoffs, and synergistically optimize CARS microscopy for clinical translation. The operation of the envisioned system incorporates coherent Raman micro-spectroscopy for identifying vibrational biomolecular markers of disease and single-frequency (or hyperspectral) Raman imaging of these specific biomarkers for real-time in vivo diagnostics and monitoring. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Vibrational imaging and microspectroscopies based on coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Volkmer, Andreas


    For noninvasive characterization of chemical species or biological components within a complex heterogeneous system, their intrinsic molecular vibrational properties can be used in contrast mechanisms in optical microscopy. A series of recent advances have made coherent anti-Stokes Raman scattering (CARS) microscopy a powerful technique that allows vibrational imaging with high sensitivity, high spectral resolution and three-dimensional sectioning capability. In this review, we discuss theoretical and experimental aspects of CARS microscopy in a collinear excitation beam geometry. Particular attention is given to the underlying physical principles behind the new features of CARS signal generation under tight focusing conditions. We provide a brief overview of the instrumentation of CARS microscopy and its experimental characterization by means of imaging of model systems and live unstained cells. CARS microscopy offers the possibility of spatially resolved vibrational spectroscopy, providing chemical and physical structure information of molecular specimens on the sub-micrometre length scale. We review multiplex CARS microspectroscopy allowing fast acquisition of frequency-resolved CARS spectra, time-resolved CARS microspectroscopy recording ultrafast Raman free induction decays and CARS correlation spectroscopy probing dynamical processes with chemical selectivity. (topical review)

  13. Dispersive Fourier transformation for megahertz detection of coherent stokes and anti-stokes Raman spectra (United States)

    Bohlin, Alexis; Patterson, Brian D.; Kliewer, Christopher J.


    In many fields of study, from coherent Raman microscopy on living cells to time-resolved coherent Raman spectroscopy of gas-phase turbulence and combustion reaction dynamics, the need for the capability to time-resolve fast dynamical and nonrepetitive processes has led to the continued development of high-speed coherent Raman methods and new high-repetition rate laser sources, such as pulse-burst laser systems. However, much less emphasis has been placed on our ability to detect shot to shot coherent Raman spectra at equivalently high scan rates, across the kilohertz to megahertz regime. This is beyond the capability of modern scientific charge coupled device (CCD) cameras, for instance, as would be employed with a Czerny-Turner type spectrograph. As an alternative detection strategy with megahertz spectral detection rate, we demonstrate dispersive Fourier transformation detection of pulsed (∼90 ps) coherent Raman signals in the time-domain. Instead of reading the frequency domain signal out using a spectrometer and CCD, the signal is transformed into a time-domain waveform through dispersive Fourier transformation in a long single-mode fiber and read-out with a fast sampling photodiode and oscilloscope. Molecular O- and S-branch rotational sideband spectra from both N2 and H2 were acquired employing this scheme, and the waveform is fitted to show highly quantitative agreement with a molecular model. The total detection time for the rotational spectrum was 20 ns, indicating an upper limit to the detection frequency of ∼50 MHz, significantly faster than any other reported spectrally-resolved coherent anti-Stokes Raman detection strategy to date.

  14. Quantitative detection of chemical compounds in human hair with coherent anti-Stokes Raman scattering microscopy


    Zimmerley, Maxwell; Lin, Chia-Yu; Oertel, David C.; Marsh, Jennifer M.; Ward, Jimmie L.; Potma, Eric Olaf


    Coherent anti-Stokes Raman scattering (CARS) microscopy is used to determine the distribution and concentration of selected compounds in intact human hair. By generating images based on ratiometric CARS contrast, quantitative concentration maps of both water and externally applied d-glycine are produced in the cortex of human hair fibers. Both water and d-glycine are found to homogeneously distribute throughout the cortical regions of the hair. The ability to selectively detect molecular agen...

  15. Protein secondary structure imaging with ultrabroadband multiplex coherent anti-Stokes Raman scattering (CARS) microspectroscopy. (United States)

    Bito, Kotatsu; Okuno, Masanari; Kano, Hideaki; Tokuhara, Shihomi; Naito, Satoru; Masukawa, Yoshinori; Leproux, Philippe; Couderc, Vincent; Hamaguchi, Hiro-o


    Protein secondary structures in human hair have been studied with ultrabroadband multiplex coherent anti-Stokes Raman scattering (CARS) microspectroscopy. The CARS peak-shift mapping method has been developed and applied to hair samples with and without treatments by chemical reduction and mechanical extension. It clearly visualizes the treatment induced changes in protein secondary structures and their spatial distributions. Using the new imaging technique, we found a multilayered structure in the human hair cortex.

  16. Revealing silent vibration modes of nanomaterials by detecting anti-Stokes hyper-Raman scattering with femtosecond laser pulses. (United States)

    Zeng, Jianhua; Chen, Lei; Dai, Qiaofeng; Lan, Sheng; Tie, Shaolong


    We proposed a scheme in which normal Raman scattering is coupled with hyper-Raman scattering for generating a strong anti-Stokes hyper-Raman scattering in nanomaterials by using femtosecond laser pulses. The proposal was experimentally demonstrated by using a single-layer MoS2 on a SiO2/Si substrate, a 17 nm-thick MoS2 on an Au/SiO2 substrate and a 9 nm-thick MoS2 on a SiO2-SnO2/Ag/SiO2 substrate which were confirmed to be highly efficient for second harmonic generation. A strong anti-Stokes hyper-Raman scattering was also observed in other nanomaterials possessing large second-order susceptibilities, such as silicon quantum dots self-assembled into "coffee" rings and tubular Cu-doped ZnO nanorods. In all the cases, many Raman inactive vibration modes were clearly revealed in the anti-Stokes hyper-Raman scattering. Apart from the strong anti-Stokes hyper-Raman scattering, Stokes hyper-Raman scattering with small Raman shifts was detected during the ablation process of thick MoS2 layers. It was also observed by slightly defocusing the excitation light. The detection of anti-Stokes hyper-Raman scattering may serve as a new technique for studying the Raman inactive vibration modes in nanomaterials.

  17. Femtosecond Coherent Anti-Stokes Raman Scattering Gas Phase Thermometry at 5 kHz (United States)

    Fineman, Claresta; Lucht, Robert


    Understanding the thermal instabilities occurring in turbulent combustion, such as in modern gas turbine combustors, is critical for more reliable and fuel-efficient operation. Non-intrusive laser based spectroscopy methods have been documented as the techniques of choice for turbulent combustion diagnostics. Specifically, femtosecond coherent anti-Stokes Raman scattering (fs-CARS) thermometry has been established for temporal resolution of turbulent fluctuations in flame structure and provides accurate measurements across a wide range of temperatures. Experiments performed to date include 5 kHz pure vibrational N2 chirped probe-pulse fs-CARS thermometry on non-premixed hydrogen jet diffusion flames, methane jet diffusion flames, and the DLR gas turbine model combustor (GTMC). The fs-CARS signal generation process requires precise spatial and temporal overlap of tightly focused pulsed laser beams of less than 100 fs pulse duration. Here, signal loss due to beam steering, pressure fluctuations, or shear layer density gradients can become a problem. The effect of such interferences has been investigated using high velocity flow of compressed nitrogen gas from a converging-diverging nozzle. Resulting changes in fs-CARS spectra have been studied. Funding for this work was provided by the U.S. Department of Energy, Division of Chemical Sciences, Geosciences and Biosciences.

  18. Macrophages interaction with pulmonary surfactant using coherent anti-Stokes Raman scattering (CARS) microscopy (United States)

    Ocampo, Minette; Telesford, Dana Marie; Allen, Heather


    Alveolar pulmonary surfactant, composed mostly of phospholipids, is essential for maintenance of normal lung function. However, increased production of lung surfactant can lead to many pulmonary inflammatory disorders. Alveolar macrophages are responsible for the degradation of the surfactant and exhibit increased lipid uptake in inflamated lungs. Owing to their limited clearance capability, excessive accumulation of surfactant may impair their phagocytic function. In this study, the interaction of the macrophages with different lipid components was studied using coherent anti-Stokes Raman scattering (CARS) microscopy. CARS microscopy, a nonlinear vibrational technique which combines spectroscopy and microscopy, allows noninvasive characterization and imaging of chemical species without preparation or labeling. A monolayer of THP-1 macrophages and palmitic acid-d31 on phosphate buffer solution was transferred to a coverslip using the Langmuir-Blodgett method and then imaged using CARS by mapping the CH2 stretch signal of the lipid membrane of the macrophage and C-D stretch signal from palmitic acid-d31. Preliminary results showed CARS images of the macrophage on the solid substrate and thermal degradation of the sample due to long exposure to high laser power. A contrast image is expected to be observed by mapping the CH2 and C-D signals, which can show the lipid interaction and phagocytosis of the macrophage.

  19. Compact fibre-based coherent anti-Stokes Raman scattering ...

    Indian Academy of Sciences (India)

    Abstract. We demonstrate a new approach to CARS spectroscopy by efficiently syn- thesizing synchronized narrow-bandwidth (less than 10 cm−1) pump and Stokes pulses. (frequency difference continuously tunable upto ~3000 cm−1) based on spectral compres- sion together with second harmonic generation (in ...

  20. Compact fibre-based coherent anti-Stokes Raman scattering ...

    Indian Academy of Sciences (India)

    We demonstrate a new approach to CARS spectroscopy by efficiently synthesizing synchronized narrow-bandwidth (less than 10 cm-1) pump and Stokes pulses (frequency difference continuously tunable upto ∼ 3000 cm-1) based on spectral compression together with second harmonic generation (in periodically-poled ...

  1. Wide-Field Vibrational Phase Contrast Imaging Based on Coherent Anti-Stokes Raman Scattering Holography

    International Nuclear Information System (INIS)

    Lv Yong-Gang; Ji Zi-Heng; Dong Da-Shan; Gong Qi-Huang; Shi Ke-Bin


    We propose and implement a wide-field vibrational phase contrast detection to obtain imaging of imaginary components of third-order nonlinear susceptibility in a coherent anti-Stokes Raman scattering (CARS) microscope with full suppression of the non-resonant background. This technique is based on the unique ability of recovering the phase of the generated CARS signal based on holographic recording. By capturing the phase distributions of the generated CARS field from the sample and from the environment under resonant illumination, we demonstrate the retrieval of imaginary components in the CARS microscope and achieve background free coherent Raman imaging. (paper)

  2. Quantitative detection of chemical compounds in human hair with coherent anti-Stokes Raman scattering microscopy (United States)

    Zimmerley, Maxwell; Lin, Chia-Yu; Oertel, David C.; Marsh, Jennifer M.; Ward, Jimmie L.; Potma, Eric Olaf


    Coherent anti-Stokes Raman scattering (CARS) microscopy is used to determine the distribution and concentration of selected compounds in intact human hair. By generating images based on ratiometric CARS contrast, quantitative concentration maps of both water and externally applied d-glycine are produced in the cortex of human hair fibers. Both water and d-glycine are found to homogeneously distribute throughout the cortical regions of the hair. The ability to selectively detect molecular agents in hair fibers is of direct relevance to understanding the chemical and physical mechanisms that underlie the performance of hair-care products.

  3. Rapid spectro-polarimetry to probe molecular symmetry in multiplex coherent anti-Stokes Raman scattering. (United States)

    Würthwein, Thomas; Brinkmann, Maximilian; Hellwig, Tim; Fallnich, Carsten


    We present the simultaneous detection of the spectrum and the complete polarization state of a multiplex coherent anti-Stokes Raman scattering signal with a fast division-of-amplitude spectro-polarimeter. The spectro-polarimeter is based on a commercial imaging spectrograph, a birefringent wedge prism, and a segmented polarizer. Compared to the standard rotating-retarder fixed-analyzer spectro-polarimeter, only a single measurement is required and an up to 21-fold reduced acquisition time is shown. The measured Stokes parameters allow us to differentiate between vibrational symmetries and to determine the depolarization ratio ρ by data post-processing.

  4. Tunable optical setup with high flexibility for spectrally resolved coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Bergner, G; Akimov, D; Bartelt, H; Dietzek, B; Popp, J; Schlücker, S


    A simplified setup for coherent anti-Stokes Raman scattering (CARS) microscopy is introduced, which allows for recording CARS images with 30 cm -1 excitation bandwidth for probing Raman bands between 500 and 900 cm -1 with minimal requirements for alignment. The experimental arrangement is based on electronic switching between CARS images recorded at different Raman resonances by combining a photonic crystal fiber (PCF) as broadband light source and an acousto-optical programmable dispersive filter (AOPDF) as tunable wavelength filter. Such spatial light modulator enables selection of a narrow-band spectrum to yield high vibrational contrast and hence chemical contrast in the resultant CARS images. Furthermore, an experimental approach to reconstruct spectral information from CARS image contrast is introduced

  5. Stimulated-emission pumping enabling sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering microscopy

    NARCIS (Netherlands)

    Cleff, C.; Gross, P.; Fallnich, C.; Offerhaus, Herman L.; Herek, Jennifer Lynn; Kruse, K.; Beeker, W.P.; Lee, Christopher James; Boller, Klaus J.


    We present a theoretical investigation of stimulated emission pumping to achieve sub-diffraction-limited spatial resolution in coherent anti-Stokes Raman scattering (CARS) microscopy. A pair of control light fields is used to prepopulate the Raman state involved in the CARS process prior to the CARS

  6. Coherent anti-Stokes Raman scattering microscopy (CARS): Instrumentation and applications

    International Nuclear Information System (INIS)

    Djaker, Nadia; Lenne, Pierre-Francois; Marguet, Didier; Colonna, Anne; Hadjur, Christophe; Rigneault, Herve


    Recent advances in laser physics have permitted the development of a new kind of microscopy based on stimulated Raman scattering. This new technique known as Coherent anti-Stokes Raman scattering (CARS) microscopy allows vibrational imaging with high sensitivity, high spectral resolution and three-dimensional sectioning capabilities. We review recent advances in CARS microscopy, with applications to chemical and biological systems. We also present an application of CARS microscopy with high optical resolution and spectral selectivity, in resolving structures in surface ex vivo stratum corneum by looking at the CH 2 stretching vibrational band. A strong CARS signal is backscattered from an intense forward generated CARS signal in thick samples. This makes noninvasive imaging of deep structures possible, without labeling or chemical treatments

  7. Quantitative assessment of spinal cord injury using circularly polarized coherent anti-Stokes Raman scattering microscopy (United States)

    Bae, Kideog; Zheng, Wei; Huang, Zhiwei


    We report the quantitative assessment of spinal cord injury using the circularly polarized coherent anti-Stokes Raman scattering (CP-CARS) technique together with Stokes parameters in the Poincaré sphere. The pump and Stokes excitation beams are circularly polarized to suppress both the linear polarization-dependent artifacts and the nonresonant background of tissue CARS imaging, enabling quantitative CP-CARS image analysis. This study shows that CP-CARS imaging uncovers significantly increased phase retardance of injured spinal cord tissue as compared to normal tissue, suggesting that CP-CARS is an appealing label-free imaging tool for determining the degree of tissue phase retardance, which could serve as a unique diagnostic parameter associated with nervous tissue injury.

  8. Spatially dependent Rabi oscillations: An approach to sub-diffraction-limited coherent anti-Stokes Raman-scattering microscopy

    NARCIS (Netherlands)

    Beeker, Willem; Beeker, W.P.; Lee, Christopher James; Boller, Klaus J.; Gross, P.; Cleff, Carsten; Fallnich, Carsten; Offerhaus, Herman L.; Herek, Jennifer Lynn


    We present a theoretical investigation of coherent anti-Stokes Raman scattering (CARS) that is modulated by periodically depleting the ground-state population through Rabi oscillations driven by an additional control laser. We find that such a process generates optical sidebands in the CARS spectrum

  9. Visualizing Resonances in the Complex Plane with Vibrational Phase Contrast Coherent Anti-Stokes Raman Scattering (CARS)

    NARCIS (Netherlands)

    Jurna, M.; Garbacik, E.T.; Korterik, Jeroen P.; Herek, Jennifer Lynn; Otto, Cornelis; Offerhaus, Herman L.


    In coherent anti-Stokes Raman scattering (CARS), the emitted signal carries both amplitude and phase information of the molecules in the focal volume. Most CARS experiments ignore the phase component, but its detection allows for two advantages over intensity-only CARS. First, the pure resonant

  10. Surfactant uptake dynamics in mammalian cells elucidated with quantitative coherent anti-stokes Raman scattering microspectroscopy.

    Directory of Open Access Journals (Sweden)

    Masanari Okuno

    Full Text Available The mechanism of surfactant-induced cell lysis has been studied with quantitative coherent anti-Stokes Raman scattering (CARS microspectroscopy. The dynamics of surfactant molecules as well as intracellular biomolecules in living Chinese Hamster Lung (CHL cells has been examined for a low surfactant concentration (0.01 w%. By using an isotope labeled surfactant having CD bonds, surfactant uptake dynamics in living cells has been traced in detail. The simultaneous CARS imaging of the cell itself and the internalized surfactant has shown that the surfactant molecules is first accumulated inside a CHL cell followed by a sudden leak of cytosolic components such as proteins to the outside of the cell. This finding indicates that surfactant uptake occurs prior to the cell lysis, contrary to what has been believed: surface adsorption of surfactant molecules has been thought to occur first with subsequent disruption of cell membranes. Quantitative CARS microspectroscopy enables us to determine the molecular concentration of the surfactant molecules accumulated in a cell. We have also investigated the effect of a drug, nocodazole, on the surfactant uptake dynamics. As a result of the inhibition of tubulin polymerization by nocodazole, the surfactant uptake rate is significantly lowered. This fact suggests that intracellular membrane trafficking contributes to the surfactant uptake mechanism.

  11. Insights into Caco-2 cell culture structure using coherent anti-Stokes Raman scattering (CARS) microscopy. (United States)

    Saarinen, Jukka; Sözeri, Erkan; Fraser-Miller, Sara J; Peltonen, Leena; Santos, Hélder A; Isomäki, Antti; Strachan, Clare J


    We have used coherent anti-Stokes Raman scattering (CARS) microscopy as a novel and rapid, label-free and non-destructive imaging method to gain structural insights into live intestinal epithelial cell cultures used for drug permeability testing. Specifically we have imaged live Caco-2 cells in (bio)pharmaceutically relevant conditions grown on membrane inserts. Imaging conditions were optimized, including evaluation of suitable membrane materials and media solutions, as well as tolerable laser powers for non-destructive imaging of the live cells. Lipid structures, in particular lipid droplets, were imaged within the cells on the insert membranes. The size of the individual lipid droplets increased substantially over the 21-day culturing period up to approximately 10% of the volume of the cross section of individual cells. Variation in lipid content has important implications for intestinal drug permeation testing during drug development but has received limited attention to date due to a lack of suitable analytical techniques. CARS microscopy was shown to be well suited for such analysis with the potential for in situ imaging of the same individual cell-cultures that are used for permeation studies. Overall, the method may be used to provide important information about cell monolayer structure to better understand drug permeation results. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Intracellular imaging of docosanol in living cells by coherent anti-Stokes Raman scattering microscopy (United States)

    You, Sixian; Liu, Yuan; Arp, Zane; Zhao, Youbo; Chaney, Eric J.; Marjanovic, Marina; Boppart, Stephen A.


    Docosanol is an over-the-counter topical agent that has proved to be one of the most effective therapies for treating herpes simplex labialis. However, the mechanism by which docosanol suppresses lesion formation remains poorly understood. To elucidate its mechanism of action, we investigated the uptake of docosanol in living cells using coherent anti-Stokes Raman scattering microscopy. Based on direct visualization of the deuterated docosanol, we observed highly concentrated docosanol inside living cells 24 h after drug treatment. In addition, different spatial patterns of drug accumulation were observed in different cell lines. In keratinocytes, which are the targeted cells of docosanol, the drug molecules appeared to be docking at the periphery of the cell membrane. In contrast, the drug molecules in fibroblasts appeared to accumulate in densely packed punctate regions throughout the cytoplasm. These results suggest that this molecular imaging approach is suitable for the longitudinal tracking of drug molecules in living cells to identify cell-specific trafficking and may also have implications for elucidating the mechanism by which docosanol suppresses lesion formation.

  13. Effect of scattering on coherent anti-Stokes Raman scattering (CARS) signals. (United States)

    Ranasinghesagara, Janaka C; De Vito, Giuseppe; Piazza, Vincenzo; Potma, Eric O; Venugopalan, Vasan


    We develop a computational framework to examine the factors responsible for scattering-induced distortions of coherent anti-Stokes Raman scattering (CARS) signals in turbid samples. We apply the Huygens-Fresnel wave-based electric field superposition (HF-WEFS) method combined with the radiating dipole approximation to compute the effects of scattering-induced distortions of focal excitation fields on the far-field CARS signal. We analyze the effect of spherical scatterers, placed in the vicinity of the focal volume, on the CARS signal emitted by different objects (2μm diameter solid sphere, 2μm diameter myelin cylinder and 2μm diameter myelin tube). We find that distortions in the CARS signals arise not only from attenuation of the focal field but also from scattering-induced changes in the spatial phase that modifies the angular distribution of the CARS emission. Our simulations further show that CARS signal attenuation can be minimized by using a high numerical aperture condenser. Moreover, unlike the CARS intensity image, CARS images formed by taking the ratio of CARS signals obtained using x- and y-polarized input fields is relatively insensitive to the effects of spherical scatterers. Our computational framework provide a mechanistic approach to characterizing scattering-induced distortions in coherent imaging of turbid media and may inspire bottom-up approaches for adaptive optical methods for image correction.

  14. Coherent anti-Stokes Raman scattering imaging of lipids in cancer metastasis

    International Nuclear Information System (INIS)

    Le, Thuc T; Huff, Terry B; Cheng, Ji-Xin


    Lipid-rich tumours have been associated with increased cancer metastasis and aggressive clinical behaviours. Nonetheless, pathologists cannot classify lipid-rich tumours as a clinically distinctive form of carcinoma due to a lack of mechanistic understanding on the roles of lipids in cancer development. Coherent anti-Stokes Raman scattering (CARS) microscopy is employed to study cancer cell behaviours in excess lipid environments in vivo and in vitro. The impacts of a high fat diet on cancer development are evaluated in a Balb/c mice cancer model. Intravital flow cytometry and histology are employed to enumerate cancer cell escape to the bloodstream and metastasis to lung tissues, respectively. Cancer cell motility and tissue invasion capability are also evaluated in excess lipid environments. CARS imaging reveals intracellular lipid accumulation is induced by excess free fatty acids (FFAs). Excess FFAs incorporation onto cancer cell membrane induces membrane phase separation, reduces cell-cell contact, increases surface adhesion, and promotes tissue invasion. Increased plasma FFAs level and visceral adiposity are associated with early rise in circulating tumour cells and increased lung metastasis. Furthermore, CARS imaging reveals FFAs-induced lipid accumulation in primary, circulating, and metastasized cancer cells. Lipid-rich tumours are linked to cancer metastasis through FFAs-induced physical perturbations on cancer cell membrane. Most importantly, the revelation of lipid-rich circulating tumour cells suggests possible development of CARS intravital flow cytometry for label-free detection of early-stage cancer metastasis

  15. Investigation of lipid homeostasis in living Drosophila by coherent anti-Stokes Raman scattering microscopy (United States)

    Chien, Cheng-Hao; Chen, Wei-Wen; Wu, June-Tai; Chang, Ta-Chau


    To improve our understanding of lipid metabolism, Drosophila is used as a model animal, and its lipid homeostasis is monitored by coherent anti-Stokes Raman scattering microscopy. We are able to achieve in vivo imaging of larval fat body (analogous to adipose tissue in mammals) and oenocytes (analogous to hepatocytes) in Drosophila larvae at subcellular level without any labeling. By overexpressing two lipid regulatory proteins-Brummer lipase (Bmm) and lipid storage droplet-2 (Lsd-2)-we found different phenotypes and responses under fed and starved conditions. Comparing with the control larva, we observed more lipid droplet accumulation by ˜twofold in oenocytes of fat-body-Bmm-overexpressing (FB-Bmm-overexpressing) mutant under fed condition, and less lipid by ˜fourfold in oenocytes of fat-body-Lsd-2-overexpressing (FB-Lsd-2-overexpressing) mutant under starved condition. Moreover, together with reduced size of lipid droplets, the lipid content in the fat body of FB-Bmm-overexpressing mutant decreases much faster than that of the control and FB-Lsd-2-overexpressing mutant during starvation. From long-term starvation assay, we found FB-Bmm-overexpressing mutant has a shorter lifespan, which can be attributed to faster consumption of lipid in its fat body. Our results demonstrate in vivo observations of direct influences of Bmm and Lsd-2 on lipid homeostasis in Drosophila larvae.

  16. Raman and coherent anti-Stokes Raman scattering microscopy studies of changes in lipid content and composition in hormone-treated breast and prostate cancer cells (United States)

    Potcoava, Mariana C.; Futia, Gregory L.; Aughenbaugh, Jessica; Schlaepfer, Isabel R.; Gibson, Emily A.


    Increasing interest in the role of lipids in cancer cell proliferation and resistance to drug therapies has motivated the need to develop better tools for cellular lipid analysis. Quantification of lipids in cells is typically done by destructive chromatography protocols that do not provide spatial information on lipid distribution and prevent dynamic live cell studies. Methods that allow the analysis of lipid content in live cells are therefore of great importance. Using micro-Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy, we generated a lipid profile for breast (T47D, MDA-MB-231) and prostate (LNCaP, PC3) cancer cells upon exposure to medroxyprogesterone acetate (MPA) and synthetic androgen R1881. Combining Raman spectra with CARS imaging, we can study the process of hormone-mediated lipogenesis. Our results show that hormone-treated cancer cells T47D and LNCaP have an increased number and size of intracellular lipid droplets and higher degree of saturation than untreated cells. MDA-MB-231 and PC3 cancer cells showed no significant changes upon treatment. Principal component analysis with linear discriminant analysis of the Raman spectra was able to differentiate between cancer cells that were treated with MPA, R1881, and untreated.

  17. Multiplex coherent anti-Stokes Raman scattering microspectroscopy of brain tissue with higher ranking data classification for biomedical imaging (United States)

    Pohling, Christoph; Bocklitz, Thomas; Duarte, Alex S.; Emmanuello, Cinzia; Ishikawa, Mariana S.; Dietzeck, Benjamin; Buckup, Tiago; Uckermann, Ortrud; Schackert, Gabriele; Kirsch, Matthias; Schmitt, Michael; Popp, Jürgen; Motzkus, Marcus


    Multiplex coherent anti-Stokes Raman scattering (MCARS) microscopy was carried out to map a solid tumor in mouse brain tissue. The border between normal and tumor tissue was visualized using support vector machines (SVM) as a higher ranking type of data classification. Training data were collected separately in both tissue types, and the image contrast is based on class affiliation of the single spectra. Color coding in the image generated by SVM is then related to pathological information instead of single spectral intensities or spectral differences within the data set. The results show good agreement with the H&E stained reference and spontaneous Raman microscopy, proving the validity of the MCARS approach in combination with SVM.

  18. A high-resolution two-pulse coherent anti-Stokes Raman scattering spectrum using a spectral amplitude modulation

    International Nuclear Information System (INIS)

    Lu, Chenhui; Zhang, Shian; Wu, Meizhen; Jia, Tianqing; Sun, Zhenrong; Qiu, Jianrong


    Femtosecond coherent anti-Stokes Raman scattering (CARS) spectra suffer from low spectral resolution because of the broadband laser spectrum. In this paper, we propose a feasible scheme to achieve a high-resolution two-pulse CARS spectrum by shaping both the pump and probe pulses using rectangular amplitude modulation. We show that a narrowband hole in the CARS spectrum can be created by the amplitude-shaped laser pulse, the position of which is correlated with the Raman resonant frequency of the molecule. Thus, by observing holes in the CARS spectrum, we are able to obtain a high-resolution CARS spectrum and the energy-level diagram of the molecule. (paper)

  19. Evans blue dye-enhanced imaging of the brain microvessels using spectral focusing coherent anti-Stokes Raman scattering microscopy.

    Directory of Open Access Journals (Sweden)

    Bo-Ram Lee

    Full Text Available We performed dye-enhanced imaging of mouse brain microvessels using spectral focusing coherent anti-Stokes Raman scattering (SF-CARS microscopy. The resonant signals from C-H stretching in forward CARS usually show high background intensity in tissues, which makes CARS imaging of microvessels difficult. In this study, epi-detection of back-scattered SF-CARS signals showed a negligible background, but the overall intensity of resonant CARS signals was too low to observe the network of brain microvessels. Therefore, Evans blue (EB dye was used as contrasting agent to enhance the back-scattered SF-CARS signals. Breakdown of brain microvessels by inducing hemorrhage in a mouse was clearly visualized using backward SF-CARS signals, following intravenous injection of EB. The improved visualization of brain microvessels with EB enhanced the sensitivity of SF-CARS, detecting not only the blood vessels themselves but their integrity as well in the brain vasculature.

  20. Combining deep learning and coherent anti-Stokes Raman scattering imaging for automated differential diagnosis of lung cancer (United States)

    Weng, Sheng; Xu, Xiaoyun; Li, Jiasong; Wong, Stephen T. C.


    Lung cancer is the most prevalent type of cancer and the leading cause of cancer-related deaths worldwide. Coherent anti-Stokes Raman scattering (CARS) is capable of providing cellular-level images and resolving pathologically related features on human lung tissues. However, conventional means of analyzing CARS images requires extensive image processing, feature engineering, and human intervention. This study demonstrates the feasibility of applying a deep learning algorithm to automatically differentiate normal and cancerous lung tissue images acquired by CARS. We leverage the features learned by pretrained deep neural networks and retrain the model using CARS images as the input. We achieve 89.2% accuracy in classifying normal, small-cell carcinoma, adenocarcinoma, and squamous cell carcinoma lung images. This computational method is a step toward on-the-spot diagnosis of lung cancer and can be further strengthened by the efforts aimed at miniaturizing the CARS technique for fiber-based microendoscopic imaging.

  1. Method and system to measure temperature of gases using coherent anti-stokes doppler spectroscopy (United States)

    Rhodes, Mark


    A method of measuring a temperature of a noble gas in a chamber includes providing the noble gas in the chamber. The noble gas is characterized by a pressure and a temperature. The method also includes directing a first laser beam into the chamber and directing a second laser beam into the chamber. The first laser beam is characterized by a first frequency and the second laser beam is characterized by a second frequency. The method further includes converting at least a portion of the first laser beam and the second laser beam into a coherent anti-Stokes beam, measuring a Doppler broadening of the coherent anti-Stokes beam, and computing the temperature using the Doppler broadening.

  2. Effects of collisions on electronic-resonance-enhanced coherent anti-Stokes Raman scattering of nitric oxide (United States)

    Patnaik, Anil K.; Roy, Sukesh; Gord, James R.; Lucht, Robert P.; Settersten, Thomas B.


    A six-level model is developed and used to study the effects of collisional energy transfer and dephasing on electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) in nitric oxide. The model includes the three levels that are coherently coupled by the three applied lasers as well as three additional bath levels that enable inclusion of the effects of electronic quenching and rotational energy transfer. The density-matrix equations that describe the evolution of the relevant populations and coherences are presented. The parametric dependencies of the ERE-CARS signal on collisional energy transfer and dephasing processes are described in terms of both a steady-state analytical solution and the numerical solutions to the governing equations. In the weak-field limit, the ERE-CARS signal scales inversely with the square of the dephasing rates for the electronic and Raman coherences. In accord with published experimental observations [Roy et al., Appl. Phys. Lett. 89, 104105 (2006)], the ERE-CARS signal is shown to be insensitive to the collisional quenching rate. Parametric dependencies on quenching, rotational energy transfer, and pure electronic dephasing are presented, demonstrating reduced collisional dependence for saturating laser fields.

  3. Effects of moderate pump and Stokes chirp on chirped-probe pulse femtosecond coherent anti-Stokes Raman scattering thermometry

    KAUST Repository

    Gu, Mingming


    The effects of moderate levels of chirp in the pump and Stokes pulses on chirped-probe-pulse femtosecond coherent anti-Stokes Raman scattering (CPP fs CARS) were investigated. The frequency chirp in the pump and Stokes pulses was introduced by placing SF11 glass disks with thicknesses of 10 mm or 20 mm in the optical path for these beams. The magnitude of the chirp in the probe beam was much greater and was induced by placing a 30-cm rod of SF10 glass in the beam path. The temperature measurements were performed in hydrogen/air non-premixed flames stabilized on a Hencken burner at equivalence ratios of 0.3, 0.5, 0.7, and 1.0. We performed measurements with no disks in pump and Stokes beam paths, and then with disks of 10 mm and 20 mm placed in both beam paths. The spectrum of the nonresonant background four-wave mixing signal narrowed considerably with increasing pump and Stokes chirp, while the resonant CARS signal was relatively unaffected. Consequently, the interference of the nonresonant background with the resonant CARS signal in the frequency-spread dephasing region of the spectrum was minimized. The increased rate of decay of the resonant CARS signal with increasing temperature was thus readily apparent. We have started to analyze the CPP fs CARS thermometry data and initial results indicate improved accuracy and precision are obtained due to moderate chirp in the pump and Stokes laser pulses.

  4. Quantitative chemical imaging with background-free multiplex coherent anti-Stokes Raman scattering by dual-soliton Stokes pulses (United States)

    Chen, Kun; Wu, Tao; Wei, Haoyun; Zhou, Tian; Li, Yan


    Coherent anti-Stokes Raman microscopy (CARS) is a quantitative, chemically specific, and label-free optical imaging technique for studying inhomogeneous systems. However, the complicating influence of the nonresonant response on the CARS signal severely limits its sensitivity and specificity and especially limits the extent to which CARS microscopy has been used as a fully quantitative imaging technique. On the basis of spectral focusing mechanism, we establish a dual-soliton Stokes based CARS microspectroscopy and microscopy scheme capable of quantifying the spatial information of densities and chemical composition within inhomogeneous samples, using a single fiber laser. Dual-soliton Stokes scheme not only removes the nonresonant background but also allows robust acquisition of multiple characteristic vibrational frequencies. This all-fiber based laser source can cover the entire fingerprint (800-2200 cm−1) region with a spectral resolution of 15 cm−1. We demonstrate that quantitative degree determination of lipid-chain unsaturation in the fatty acids mixture can be achieved by the characterization of C = C stretching and CH2 deformation vibrations. For microscopy purposes, we show that the spatially inhomogeneous distribution of lipid droplets can be further quantitatively visualized using this quantified degree of lipid unsaturation in the acyl chain for contrast in the hyperspectral CARS images. The combination of compact excitation source and background-free capability to facilitate extraction of quantitative composition information with multiplex spectral peaks will enable wider applications of quantitative chemical imaging in studying biological and material systems. PMID:27867704

  5. Detection of Lipid-Rich Prostate Circulating Tumour Cells with Coherent Anti-Stokes Raman Scattering Microscopy

    International Nuclear Information System (INIS)

    Mitra, Ranjana; Chao, Olivia; Urasaki, Yasuyo; Goodman, Oscar B; Le, Thuc T


    Circulating tumour cells (CTC) are an important indicator of metastasis and associated with a poor prognosis. Detection sensitivity and specificity of CTC in the peripheral blood of metastatic cancer patient remain a technical challenge. Coherent anti-Stokes Raman scattering (CARS) microscopy was employed to examine the lipid content of CTC isolated from the peripheral blood of metastatic prostate cancer patients. CARS microscopy was also employed to evaluate lipid uptake and mobilization kinetics of a metastatic human prostate cancer cell line. One hundred CTC from eight metastatic prostate cancer patients exhibited strong CARS signal which arose from intracellular lipid. In contrast, leukocytes exhibited weak CARS signal which arose mostly from cellular membrane. On average, CARS signal intensity of prostate CTC was 7-fold higher than that of leukocytes (P<0.0000001). When incubated with human plasma, C4-2 metastatic human prostate cancer cells exhibited rapid lipid uptake kinetics and slow lipid mobilization kinetics. Higher expression of lipid transport proteins in C4-2 cells compared to non-transformed RWPE-1 and non-malignant BPH-1 prostate epithelial cells further indicated strong affinity for lipid of metastatic prostate cancer cells. Intracellular lipid could serve as a biomarker for prostate CTC which could be sensitively detected with CARS microscopy in a label-free manner. Strong affinity for lipid by metastatic prostate cancer cells could be used to improve detection sensitivity and therapeutic targeting of prostate CTC

  6. Paranodal myelin retraction in relapsing experimental autoimmune encephalomyelitis visualized by coherent anti-Stokes Raman scattering microscopy (United States)

    Fu, Yan; Frederick, Terra J.; Huff, Terry B.; Goings, Gwendolyn E.; Miller, Stephen D.; Cheng, Ji-Xin


    How demyelination is initiated is a standing question for pathology of multiple sclerosis. By label-free coherent anti-Stokes Raman scattering (CARS) imaging of myelin lipids, we investigate myelin integrity in the lumbar spinal cord tissue isolated from naïve SJL mice, and from mice at the onset, peak acute, and remission stages of relapsing experimental autoimmune encephalomyelitis (EAE). Progressive demyelinating disease is initially characterized by the retraction of paranodal myelin both at the onset of disease and at the borders of acute demyelinating lesions. Myelin retraction is confirmed by elongated distribution of neurofascin proteins visualized by immunofluorescence. The disruption of paranodal myelin subsequently exposes Kv1.2 channels at the juxtaparanodes and lead to the displacement of Kv1.2 channels to the paranodal and nodal domains. Paranodal myelin is partially restored during disease remission, indicating spontaneous myelin regeneration. These findings suggest that paranodal domain injury precedes formation of internodal demyelinating lesions in relapsing EAE. Our results also demonstrate that CARS microscopy is an effective readout of myelin disease burden.

  7. Effects of phase and coupling between the vibrational modes on selective excitation in coherent anti-Stokes Raman scattering microscopy

    International Nuclear Information System (INIS)

    Patel, Vishesha; Malinovsky, Vladimir S.; Malinovskaya, Svetlana


    Coherent anti-Stokes Raman scattering (CARS) microscopy has been a major tool of investigation of biological structures as it contains the vibrational signature of molecules. A quantum control method based on chirped pulse adiabatic passage was recently proposed for selective excitation of a predetermined vibrational mode in CARS microscopy [Malinovskaya and Malinovsky, Opt. Lett. 32, 707 (2007)]. The method utilizes the chirp sign variation at the peak pulse amplitude and gives a robust adiabatic excitation of the desired vibrational mode. Using this method, we investigate the impact of coupling between vibrational modes in molecules on controllability of excitation of the CARS signal. We analyze two models of two coupled two-level systems (TLSs) having slightly different transitional frequencies. The first model, featuring degenerate ground states of the TLSs, gives robust adiabatic excitation and maximum coherence in the resonant TLS for positive value of the chirp. In the second model, implying nondegenerate ground states in the TLSs, a population distribution is observed in both TLSs, resulting in a lack of selectivity of excitation and low coherence. It is shown that the relative phase and coupling between the TLSs play an important role in optimizing coherence in the desired vibrational mode and suppressing unwanted transitions in CARS microscopy.

  8. Exploring the interactions between peptides and lipid bilayers using coherent anti-Stokes Raman scattering and two-photon fluorescence (United States)

    Mari, M.; Mouras, R.; Downes, A.; Elfick, A.


    We have used a versatile and powerful microscope[1] for multi-modal biomedical imaging on which we combine Coherent Anti-Stokes Raman Scattering (CARS) with Two Photon Excitation Fluorescence (TPEF) using a Nd: YVO4 pump laser. We acquired 2PEF, CARS, and phase contrast images of Multilamellar Vesicles (MLVs) and Giant Unilamellar Vesicles (GUVs), as well as Raman spectra of the constituent lipids. A wide range of peptides are harmful to cells by altering the structure of the biological membranes. This effect depends on the composition of the membrane and the chemical structure of the peptide. The peptide we studied is the beta amyloid Aβ which is a major component of the amyloid plaques deposited on neuronal membranes of Alzheimer's disease (AD) patients. AD is neurodegenerative disorder in which the hallmark symptoms include cognitive decline and dementia[2] and is characterized by the formation of extracellular amyloid fibrils on the neuronal membranes of the brain. Many questions still remain unanswered concerning the destabilization of cellular ionic homeostasis due to pores formed during the interactions of lipid membranes with peptides. In this project, biomimics of cell membranes are used. The structures that best mimic the plasma membranes are MLVs or GUVs. These vesicles are formed using the gentle hydration technique[3] or the electroformation technique[4] respectively and are composed of phospholipids such as DOPC, DPPC, D62PPC and their binary mixtures. The MLVs and GUVs imaging by CARS and TPEF microscopy not only permits the direct imaging of the leakage phenomenon caused by the toxic peptide (Aβ) on the lipid bilayer, but also records simultaneously the lateral structure of the bilayer and peptide distribution in the plane across the membrane.

  9. Raman spectroscopy (United States)

    Raman spectroscopy has gained increased use and importance in recent years for accurate and precise detection of physical and chemical properties of food materials, due to the greater specificity and sensitivity of Raman techniques over other analytical techniques. This book chapter presents Raman s...

  10. Raman Spectroscopy. (United States)

    Gerrard, Donald L.


    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…

  11. Ultrafast surface-enhanced Raman spectroscopy. (United States)

    Keller, Emily L; Brandt, Nathaniel C; Cassabaum, Alyssa A; Frontiera, Renee R


    Ultrafast surface-enhanced Raman spectroscopy (SERS) with pico- and femtosecond time resolution has the ability to elucidate the mechanisms by which plasmons mediate chemical reactions. Here we review three important technological advances in these new methodologies, and discuss their prospects for applications in areas including plasmon-induced chemistry and sensing at very low limits of detection. Surface enhancement, arising from plasmonic materials, has been successfully incorporated with stimulated Raman techniques such as femtosecond stimulated Raman spectroscopy (FSRS) and coherent anti-Stokes Raman spectroscopy (CARS). These techniques are capable of time-resolved measurement on the femtosecond and picosecond time scale and can be used to follow the dynamics of molecules reacting near plasmonic surfaces. We discuss the potential application of ultrafast SERS techniques to probe plasmon-mediated processes, such as H2 dissociation and solar steam production. Additionally, we discuss the possibilities for high sensitivity SERS sensing using these stimulated Raman spectroscopies.

  12. In planta imaging of Δ9-tetrahydrocannabinolic acid in Cannabis sativa L. with hyperspectral coherent anti-Stokes Raman scattering microscopy (United States)

    Garbacik, Erik T.; Korai, Roza P.; Frater, Eric H.; Korterik, Jeroen P.; Otto, Cees; Offerhaus, Herman L.


    Nature has developed many pathways to produce medicinal products of extraordinary potency and specificity with significantly higher efficiencies than current synthetic methods can achieve. Identification of these mechanisms and their precise locations within plants could substantially increase the yield of a number of natural pharmaceutics. We report label-free imaging of Δ9-tetrahydrocannabinolic acid (THCa) in Cannabis sativa L. using coherent anti-Stokes Raman scattering microscopy. In line with previous observations we find high concentrations of THCa in pistillate flowering bodies and relatively low amounts within flowering bracts. Surprisingly, we find differences in the local morphologies of the THCa-containing bodies: organelles within bracts are large, diffuse, and spheroidal, whereas in pistillate flowers they are generally compact, dense, and have heterogeneous structures. We have also identified two distinct vibrational signatures associated with THCa, both in pure crystalline form and within Cannabis plants; at present the exact natures of these spectra remain an open question.

  13. Investigation of protein distribution in solid lipid particles and its impact on protein release using coherent anti-Stokes Raman scattering microscopy

    DEFF Research Database (Denmark)

    Christophersen, Philip C.; Birch, Ditlev; Saarinen, Jukka


    The aim of this study was to gain new insights into protein distribution in solid lipid microparticles (SLMs) and subsequent release mechanisms using a novel label-free chemical imaging method, coherent anti-Stokes Raman scattering (CARS) microscopy. Lysozyme-loaded SLMs were prepared using...... in the solid lipid matrix, which required full lipolysis of the entire matrix to release lysozyme completely. Therefore, SLMs with lysozyme incorporated in an aqueous solution released lysozyme much faster than with lysozyme incorporated as a solid. In conclusion, CARS microscopy was an efficient and non......-destructive method for elucidating the distribution of lysozyme in SLMs. The interpretation of protein distribution and release during lipolysis enabled elucidation of protein release mechanisms. In future, CARS microscopy analysis could facilitate development of a wide range of protein-lipid matrices with tailor...

  14. Coherent Anti-Stokes and Coherent Stokes in Raman Scattering by Superconducting Nanowire Single-Photon Detector for Temperature Measurement

    Directory of Open Access Journals (Sweden)

    Annepu Venkata Naga Vamsi


    Full Text Available We have reported the measurement of temperature by using coherent anti-Stroke and coherent Stroke Raman scattering using superconducting nano wire single-photon detector. The measured temperatures by both methods (Coherent Anti-Raman scattering & Coherent Stroke Raman scattering and TC 340 are in good accuracy of ± 5 K temperature range. The length of the pipe line under test can be increased by increasing the power of the pump laser. This methodology can be widely used to measure temperatures at instantaneous positions in test pipe line or the entire temperature of the pipe line under test.

  15. Label-free assessment of adipose-derived stem cell differentiation using coherent anti-Stokes Raman scattering and multiphoton microscopy (United States)

    Mouras, Rabah; Bagnaninchi, Pierre O.; Downes, Andrew R.; Elfick, Alistair P. D.


    Adult stem cells (SCs) hold great potential as likely candidates for disease therapy but also as sources of differentiated human cells in vitro models of disease. In both cases, the label-free assessment of SC differentiation state is highly desirable, either as a quality-control technology ensuring cells to be used clinically are of the desired lineage or to facilitate in vitro time-course studies of cell differentiation. We investigate the potential of nonlinear optical microscopy as a minimally invasive technology to monitor the differentiation of adipose-derived stem cells (ADSCs) into adipocytes and osteoblasts. The induction of ADSCs toward these two different cell lineages was monitored simultaneously using coherent anti-Stokes Raman scattering, two photon excitation fluorescence (TPEF), and second harmonic generation at different time points. Changes in the cell's morphology, together with the appearance of biochemical markers of cell maturity were observed, such as lipid droplet accumulation for adipo-induced cells and the formation of extra-cellular matrix for osteo-induced cells. In addition, TPEF of flavoproteins was identified as a proxy for changes in cell metabolism that occurred throughout ADSC differentiation toward both osteoblasts and adipocytes. These results indicate that multimodal microscopy has significant potential as an enabling technology for the label-free investigation of SC differentiation.

  16. Label-free imaging of Drosophila in vivo by coherent anti-Stokes Raman scattering and two-photon excitation autofluorescence microscopy (United States)

    Chien, Cheng-Hao; Chen, Wei-Wen; Wu, June-Tai; Chang, Ta-Chau


    Drosophila is one of the most valuable model organisms for studying genetics and developmental biology. The fat body in Drosophila, which is analogous to the liver and adipose tissue in human, stores lipids that act as an energy source during its development. At the early stages of metamorphosis, the fat body remodeling occurs involving the dissociation of the fat body into individual fat cells. Here we introduce a combination of coherent anti-Stokes Raman scattering (CARS) and two-photon excitation autofluorescence (TPE-F) microscopy to achieve label-free imaging of Drosophila in vivo at larval and pupal stages. The strong CARS signal from lipids allows direct imaging of the larval fat body and pupal fat cells. In addition, the use of TPE-F microscopy allows the observation of other internal organs in the larva and autofluorescent globules in fat cells. During the dissociation of the fat body, the findings of the degradation of lipid droplets and an increase in autofluorescent globules indicate the consumption of lipids and the recruitment of proteins in fat cells. Through in vivo imaging and direct monitoring, CARS microscopy may help elucidate how metamorphosis is regulated and study the lipid metabolism in Drosophila.

  17. Dual-pump coherent anti-Stokes Raman scattering system for temperature and species measurements in an optically accessible high-pressure gas turbine combustor facility (United States)

    Thariyan, Mathew P.; Bhuiyan, Aizaz H.; Meyer, Scott E.; Naik, Sameer V.; Gore, Jay P.; Lucht, Robert P.


    The development and implementation of a dual-pump coherent anti-Stokes Raman scattering (DP-CARS) system employing two optical sub-systems to measure temperature and major species concentrations at multiple locations in the flame zone of a high-pressure, liquid-fueled gas turbine combustor are discussed. An optically accessible gas turbine combustor facility (GTCF) was utilized to perform these experiments. A window assembly has been designed, fabricated, and assembled in the GTCF to allow optical access from three directions using a pair of thin and thick fused silica windows on each side. A lean direct injection (LDI) device consisting of an array of nine integrated air swirlers and fuel injectors was operated using Jet-A fuel at inlet air temperatures up to 725 K and combustor pressures up to 1.03 MPa. The DP-CARS system was used to measure temperature and CO2/N2 concentration ratio on single laser shots. An injection-seeded optical parametric oscillator (OPO) was used as a narrowband pump laser source in order to potentially reduce shot-to-shot fluctuations in the CARS data. Large prisms mounted on computer-controlled translation stages were used to direct the CARS beams either into the main leg optical system for measurements in the GTCF or to a reference leg optical system for measurements of the non-resonant spectrum and for alignment of the CARS system. The spatial maps of temperature and major species concentrations were obtained in high-pressure LDI flames by translating the CARS probe volume in the axial and vertical directions inside the combustor rig without loss of optical alignment.

  18. Coherent anti-Stokes Raman scattering for quantitative temperature and concentration measurements in a high-pressure gas turbine combustor rig (United States)

    Thariyan, Mathew Paul

    Dual-pump coherent anti-Stokes Raman scattering (DP-CARS) temperature and major species (CO2/N2) concentration measurements have been performed in an optically-accessible high-pressure gas turbine combustor facility (GTCF) and for partially-premixed and non-premixed flames in a laminar counter-flow burner. A window assembly incorporating pairs of thin and thick fused silica windows on three sides was designed, fabricated, and assembled in the GTCF for advanced laser diagnostic studies. An injection-seeded optical parametric oscillator (OPO) was used as a narrowband pump laser source in the dual-pump CARS system. Large prisms on computer-controlled translation stages were used to direct the CARS beams either into the main optics leg for measurements in the GTCF or to a reference optics leg for measurements of the nonresonant CARS spectrum and for aligning the CARS system. Combusting flows were stabilized with liquid fuel injection only for the central injector of a 9-element lean direct injection (LDI) device developed at NASA Glenn Research Center. The combustor was operated using Jet A fuel at inlet air temperatures up to 725 K and combustor pressures up to 1.03 MPa. Single-shot DP-CARS spectra were analyzed using the Sandia CARSFT code in the batch operation mode to yield instantaneous temperature and CO2/N2 concentration ratio values. Spatial maps of mean and standard deviations of temperature and CO2/N2 concentrations were obtained in the high-pressure LDI flames by translating the CARS probe volume in axial and vertical directions inside the combustor rig. The mean temperature fields demonstrate the effect of the combustor conditions on the overall flame length and the average flame structure. The temperature relative standard deviation values indicate thermal fluctuations due to the presence of recirculation zones and/or flame brush fluctuations. The correlation between the temperature and relative CO 2 concentration data has been studied at various combustor

  19. Coherent Raman spectroscopy

    CERN Document Server

    Eesley, G L


    Coherent Raman Spectroscopy provides a unified and general account of the fundamental aspects of nonlinear Raman spectroscopy, also known as coherent Raman spectroscopy. The theoretical basis from which coherent Raman spectroscopy developed is described, along with its applications, utility, and implementation as well as advantages and disadvantages. Experimental data which typifies each technique is presented. This book is comprised of four chapters and opens with an overview of nonlinear optics and coherent Raman spectroscopy, followed by a discussion on nonlinear transfer function of matter

  20. Remote detection of chem/bio hazards via coherent anti-Stokes Raman spectroscopy (United States)


    Department of Physics & Engineering Physics Stevens Institute of Technology Hobokcn1 L J 07030 Ph.: (201) 216-8094, (734) 717-3604 Fa,x: (201) 216-5638...asynunetTic 2942 crri-1 (88.20THz) st.retch mode. The frequency of these viba1- tional modes is slightly different allowing to test t he chemical

  1. High-resolution inverse Raman and resonant-wave-mixing spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rahn, L.A. [Sandia National Laboratories, Livermore, CA (United States)


    These research activities consist of high-resolution inverse Raman spectroscopy (IRS) and resonant wave-mixing spectroscopy to support the development of nonlinear-optical techniques for temperature and concentration measurements in combustion research. Objectives of this work include development of spectral models of important molecular species needed to perform coherent anti-Stokes Raman spectroscopy (CARS) measurements and the investigation of new nonlinear-optical processes as potential diagnostic techniques. Some of the techniques being investigated include frequency-degenerate and nearly frequency-degenerate resonant four-wave-mixing (DFWM and NDFWM), and resonant multi-wave mixing (RMWM).

  2. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 15; Issue 2. Surface-Enhanced Raman Spectroscopy - Recent Advancement of Raman Spectroscopy. Ujjal Kumar Sur. General Article Volume 15 Issue 2 February 2010 pp 154-164 ...

  3. Raman spectroscopy using a spatial heterodyne spectrometer: proof of concept. (United States)

    Gomer, Nathaniel R; Gordon, Christopher M; Lucey, Paul; Sharma, Shiv K; Carter, J Chance; Angel, S Michael


    The use of a spatial heterodyne interferometer-based spectrometer (SHS) for Raman spectroscopy is described. The motivation for this work is to develop a small, rugged, high-resolution ultraviolet (UV) Raman spectrometer that is compatible with pulsed laser sources and that is suitable for planetary space missions. UV Raman is a particular technical challenge for space applications because dispersive (grating) approaches require large spectrographs and very narrow slits to achieve the spectral resolution required to maximize the potential of Raman spectroscopy. The heterodyne approach of the SHS has only a weak coupling of resolution and throughput, so a high-resolution UV SHS can both be small and employ a wide slit to maximize throughput. The SHS measures all optical path differences in its interferogram simultaneously with a detector array, so the technique is compatible with gated detection using pulsed lasers, important to reject ambient background and mitigate fluorescence (already low in the UV) that might be encountered on a planetary surface where samples are uncontrolled. The SHS has no moving parts, and as the spectrum is heterodyned around the laser wavelength, it is particularly suitable for Raman measurements. In this preliminary report we demonstrate the ability to measure visible wavelength Raman spectra of liquid and solid materials using an SHS Raman spectrometer and a visible laser. Spectral resolution and bandpass are also discussed. Separation of anti-Stokes and Stokes Raman bands is demonstrated using two different approaches. Finally spectral bandpass doubling is demonstrated by forming an interference pattern in both directions on the ICCD detector followed by analysis using a two-dimensional Fourier transform.

  4. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    In Raman spectroscopy, inelastic scattering of photons from an atom or molecule in chemical entities is utilized to analyze the composition of solids, liquids and gases. However, the low cross-section limits its applications. The introduction of sur- face-enhanced Raman spectroscopy in 1974 has attracted a lot of attention ...

  5. Diffusion measurements by Raman spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Shapiro, Alexander; Berg, Rolf W.

    Poster "Diffusion measurements by Raman spectroscopy", See poster at "Diffusion measurements by Raman spectroscopy", See poster at

  6. Industrial applications of Raman spectroscopy (United States)

    Grasselli, J. G.; Walder, F.; Petty, C.; Kemeny, G.


    In the last two decades, Raman spectroscopy has matured as an important method for the study of molecules and complex molecular systems. This is evident from the number of fine texts and the many review articles which have been published describing theory and applications of Raman spectroscopy over a very broad range of subjects (1-10). Raman spectroscopy is the essential partner to infrared spectroscopy for a complete vibrational analysis of a molecule in structure determinations. From the understanding developed on small molecules, theory was extended to interpret the spectra of larger systems such as polymers, biological molecules, and ordered condensed phases. The contribution of Raman spectroscopy to these areas has been significant. It was the development of commercial lasers in the 1960s which spurred the renewed interest in the Raman technique. But applications were still limited for highly fluorescing or intensely colored systems. In 1986, a breakthrough paper by Hirschfeld and Chase (11) described the use of near-infrared laser excitation and a commercial interferometer-based FT-IR spectrometer to record FT-Raman spectra. Significant advantages included the inherent multiplex, throughput and data processing features of the FT interferometers and the use of a ND:YAG laser (1.064 μm) which dramatically decreased problems with sample fluorescence and decomposition. A deluge of papers describing applications of FT-Raman spectroscopy can be found in the Journal of Raman Spectroscopy, Spectrochimica Acta (special issues 40A ad 47A), and Applied Spectroscopy since then.

  7. Tackling field-portable Raman spectroscopy of real world samples (United States)

    Shand, Neil C.


    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.

  8. Surface-Enhanced Raman Spectroscopy

    Indian Academy of Sciences (India)

    IAS Admin

    near-ultraviolet range of electromagnetic spectra. The shift in energy in Raman effect gives information about the ... Raman spectroscopy is commonly used in chemistry, since vibrational information is very specific for the ... in polarizability is compatible with preservation of the center of symmetry. Thus, in a centrosymmetric ...

  9. Observation of anomalous Stokes versus anti-Stokes ratio in MoTe2 atomic layers (United States)

    Goldstein, Thomas; Chen, Shao-Yu; Xiao, Di; Ramasubramaniam, Ashwin; Yan, Jun

    We grow hexagonal molybdenum ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor, with chemical vapor transport methods and investigate its atomic layers with Stokes and anti-Stokes Raman scattering. We report observation of all six types of zone center optical phonons. Quite remarkably, the anti-Stokes Raman intensity of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain experimental conditions, creating an illusion of 'negative temperature'. This effect is tunable, and can be switched from anti-Stokes enhancement to suppression by varying the excitation wavelength. We interpret this observation to be a result of resonance effects arising from the C excitons in the vicinity of the Brillouin zone center, which are robust even for multiple layers of MoTe2. The intense anti-Stokes Raman scattering provides a cooling channel for the crystal and opens up opportunities for laser cooling of atomically thin TMDC semiconductor devices. Supported by the University of Massachusetts Amherst, the National Science Foundation Center for Hierarchical Manufacturing (CMMI-1025020) and Office of Emerging Frontiers in Research and Innovation (EFRI-1433496).

  10. Raman Spectroscopy and Microscopy of Individual Cells andCellular Components

    Energy Technology Data Exchange (ETDEWEB)

    Chan, J; Fore, S; Wachsmann-Hogiu, S; Huser, T


    Raman spectroscopy provides the unique opportunity to non-destructively analyze chemical concentrations on the submicron length scale in individual cells without the need for optical labels. This enables the rapid assessment of cellular biochemistry inside living cells, and it allows for their continuous analysis to determine cellular response to external events. Here, we review recent developments in the analysis of single cells, subcellular compartments, and chemical imaging based on Raman spectroscopic techniques. Spontaneous Raman spectroscopy provides for the full spectral assessment of cellular biochemistry, while coherent Raman techniques, such as coherent anti-Stokes Raman scattering is primarily used as an imaging tool comparable to confocal fluorescence microscopy. These techniques are complemented by surface-enhanced Raman spectroscopy, which provides higher sensitivity and local specificity, and also extends the techniques to chemical indicators, i.e. pH sensing. We review the strengths and weaknesses of each technique, demonstrate some of their applications and discuss their potential for future research in cell biology and biomedicine.

  11. Sum-Frequency-Generation-Based Laser Sidebands for Tunable Femtosecond Raman Spectroscopy in the Ultraviolet

    Directory of Open Access Journals (Sweden)

    Liangdong Zhu


    Full Text Available Femtosecond stimulated Raman spectroscopy (FSRS is an emerging molecular structural dynamics technique for functional materials characterization typically in the visible to near-IR range. To expand its applications we have developed a versatile FSRS setup in the ultraviolet region. We use the combination of a narrowband, ~400 nm Raman pump from a home-built second harmonic bandwidth compressor and a tunable broadband probe pulse from sum-frequency-generation-based cascaded four-wave mixing (SFG-CFWM laser sidebands in a thin BBO crystal. The ground state Raman spectrum of a laser dye Quinolon 390 in methanol that strongly absorbs at ~355 nm is systematically studied as a standard sample to provide previously unavailable spectroscopic characterization in the vibrational domain. Both the Stokes and anti-Stokes Raman spectra can be collected by selecting different orders of SFG-CFWM sidebands as the probe pulse. The stimulated Raman gain with the 402 nm Raman pump is >21 times larger than that with the 550 nm Raman pump when measured at the 1317 cm−1 peak for the aromatic ring deformation and ring-H rocking mode of the dye molecule, demonstrating that pre-resonance enhancement is effectively achieved in the unique UV-FSRS setup. This added tunability in the versatile and compact optical setup enables FSRS to better capture transient conformational snapshots of photosensitive molecules that absorb in the UV range.

  12. Raman spectroscopy of bone metastasis (United States)

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


    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.

  13. Raman and Photoluminescence Spectroscopy in Mineral Identification (United States)

    Kuehn, J. W.


    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.

  14. Raman Spectroscopy for Homeland Security Applications

    Directory of Open Access Journals (Sweden)

    Gregory Mogilevsky


    Full Text Available Raman spectroscopy is an analytical technique with vast applications in the homeland security and defense arenas. The Raman effect is defined by the inelastic interaction of the incident laser with the analyte molecule’s vibrational modes, which can be exploited to detect and identify chemicals in various environments and for the detection of hazards in the field, at checkpoints, or in a forensic laboratory with no contact with the substance. A major source of error that overwhelms the Raman signal is fluorescence caused by the background and the sample matrix. Novel methods are being developed to enhance the Raman signal’s sensitivity and to reduce the effects of fluorescence by altering how the hazard material interacts with its environment and the incident laser. Basic Raman techniques applicable to homeland security applications include conventional (off-resonance Raman spectroscopy, surface-enhanced Raman spectroscopy (SERS, resonance Raman spectroscopy, and spatially or temporally offset Raman spectroscopy (SORS and TORS. Additional emerging Raman techniques, including remote Raman detection, Raman imaging, and Heterodyne imaging, are being developed to further enhance the Raman signal, mitigate fluorescence effects, and monitor hazards at a distance for use in homeland security and defense applications.

  15. Raman spectroscopy peer review report

    International Nuclear Information System (INIS)

    Winkelman, W.D.; Eberlein, S.J.


    The Hanford Site in eastern Washington includes 177 underground storage tanks (UST), which contain waste materials produced during the production of nuclear fuels. The materials in the tanks must be characterized to support the retrieval, processing, and final disposition of the waste. Characterization is currently performed by removing waste samples for analyses in a hot cell or laboratory. A review of the Hanford Raman Spectroscopy Program was held in Richland on March 23 and 24, 1994. A team of principal investigators and researchers made presentations that covered both technical and programmatic aspects of the Hanford Site Raman work. After these presentations and discussions, the review panel met in a closed session to formalize a list of findings. The reviewers agreed that Raman spectroscopy is an excellent method to attack the tank waste characterization and screening problems that were presented. They agreed that there was a good chance that the method would be successful as presently envisioned. The reviewers provided the following primary recommendations: evaluation a laser with wavelength in the near infrared; provide optical filters at or near the sampling end of the fiber-optic probe; develop and implement a strategy for frequent calibration of the system; do not try to further increase Raman resolution at the expense of wavelength range; clearly identify and differentiate between requirements for providing a short-term operational system and requirements for optimizing a system for long-term field use; and determine the best optical configuration, which may include reduced fiber-optic diameter and/or short focal length and low F-number spectrographs

  16. Raman Spectroscopy and its Application in Nanostructures

    CERN Document Server

    Zhang, Shu-Lin


    Raman Spectroscopy and its Application in Nanostructures is an original and timely contribution to a very active area of physics and materials science research. This book presents the theoretical and experimental phenomena of Raman spectroscopy, with specialized discussions on the physical fundamentals, new developments and main features in low-dimensional systems of Raman spectroscopy. In recent years physicists, materials scientists and chemists have devoted increasing attention to low-dimensional systems and as Raman spectroscopy can be used to study and analyse such materials as carbon nan

  17. Raman Plus X: Biomedical Applications of Multimodal Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Nandan K. Das


    Full Text Available Raman spectroscopy is a label-free method of obtaining detailed chemical information about samples. Its compatibility with living tissue makes it an attractive choice for biomedical analysis, yet its translation from a research tool to a clinical tool has been slow, hampered by fundamental Raman scattering issues such as long integration times and limited penetration depth. In this review we detail the how combining Raman spectroscopy with other techniques yields multimodal instruments that can help to surmount the translational barriers faced by Raman alone. We review Raman combined with several optical and non-optical methods, including fluorescence, elastic scattering, OCT, phase imaging, and mass spectrometry. In each section we highlight the power of each combination along with a brief history and presentation of representative results. Finally, we conclude with a perspective detailing both benefits and challenges for multimodal Raman measurements, and give thoughts on future directions in the field.

  18. Investigation of the Brill transition in nylon 6,6 by Raman, THz-Raman, and two-dimensional correlation spectroscopy (United States)

    Bertoldo Menezes, D.; Reyer, A.; Musso, M.


    The Brill transition is a phase transition process in polyamides related with structural changes between the hydrogen bonds of the lateral functional groups (Cdbnd O) and (Nsbnd H). In this study, we have used the potential of Raman spectroscopy for exploring this phase transition in polyamide 6,6 (nylon 6,6), due to the sensitivity of this spectroscopic technique to small intermolecular changes affecting vibrational properties of relevant functional groups. During a step by step heating and cooling process of the sample we collected Raman spectra allowing us from two-dimensional Raman correlation spectroscopy to identify which spectral regions suffered the largest influence during the Brill transition, and from Terahertz Stokes and anti-Stokes Raman spectroscopy to obtain complementary information, e.g. on the temperature of the sample. This allowed us to grasp signatures of the Brill transition from peak parameters of vibrational modes associated with (Csbnd C) skeletal stretches and (CNH) bending, and to verify the Brill transition temperature at around 160 °C, as well as the reversibility of this phase transition.

  19. Infrared and Raman spectroscopy: principles and spectral interpretation

    National Research Council Canada - National Science Library

    Larkin, Peter


    "Infrared and Raman Spectroscopy: Principles and Spectral Interpretation explains the background, core principles and tests the readers understanding of the important techniques of Infrared and Raman Spectroscopy...

  20. Raman spectroscopy of skin neoplasms (United States)

    Moryatov, A. A.; Kozlov, S. V.; Kaganov, O. I.; Orlov, A. E.; Zaharov, V. P.; Batrachenko, I. A.; Artemiev, D. N.; Blinov, N. V.


    Skin melanoma is spread inhomogeneously worldwide, particularly in Samara region there are high figures of skin neoplasms sick rate as well—18.6%. Research goal: to develop a new method of early non-invasive differential diagnostics of skin neoplasms. Registration of Raman spectrum was implemented in the distance of 3-4 mm, the spectrum registration from pathologically changed zone was subsequently conducted, then from healthy skin zone. The test time for 1 patient was no longer than 3-5 min. In a range of experiments ex vivo there were the following results: melanoma—24, basal cell cancer—25, squamosus cell sarcinoma—7, nevus pigmentosis—9, other malignant neoplasms—6; in vivo: melanoma—9, basal cell cancer—8, nevus pigmentosis—2, other benign neoplasms—2. The first results of the research dedicated to studying permissive opportunities of Raman spectroscopy, with successive two-phase analysis of received parameters display high efficiency of method of differential diagnostic for skin melanoma and other malignant neoplasms, pigment and benign skin neoplasms. Safety and rapidity of the research reveal a high potential of the technique.

  1. Applications of Raman spectroscopy in life science (United States)

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


    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.

  2. Raman spectroscopy in pharmaceutical product design

    DEFF Research Database (Denmark)

    Paudel, Amrit; Raijada, Dhara; Rantanen, Jukka


    molecular-based drug discovery, design of innovative drug delivery systems and quality control of finished products. This review presents concise accounts of various conventional and emerging Raman instrumentations including associated hyphenated tools of pharmaceutical interest. Moreover, relevant...... application cases of Raman spectroscopy in early and late phase pharmaceutical development, process analysis and micro-structural analysis of drug delivery systems are introduced. Finally, potential areas of future advancement and application of Raman spectroscopic techniques are discussed....

  3. Basic principles of ultrafast Raman loss spectroscopy

    Indian Academy of Sciences (India)

    One such nonlinear process, namely, the third order nonlinear spectroscopy has become a popular tool to study molecular structure. Thus, the spectroscopy based on the third order optical nonlinearity called stimulated Raman spectroscopy (SRS) is a tool to extract the structural and dynamical information about a molecular ...

  4. Raman spectroscopy an intensity approach

    CERN Document Server

    Guozhen, Wu


    This book summarizes the highlights of our work on the bond polarizability approach to the intensity analysis. The topics covered include surface enhanced Raman scattering, Raman excited virtual states and Raman optical activity (ROA). The first chapter briefly introduces the Raman effect in a succinct but clear way. Chapter 2 deals with the normal mode analysis. This is a basic tool for our work. Chapter 3 introduces our proposed algorithm for the Raman intensity analysis. Chapter 4 heavily introduces the physical picture of Raman virtual states. Chapter 5 offers details so that the readers can have a comprehensive idea of Raman virtual states. Chapter 6 demonstrates how this bond polarizability algorithm is extended to ROA intensity analysis. Chapters 7 and 8 offer details on ROA, showing many findings on ROA mechanism that were not known or neglected before. Chapter 9 introduces our proposed classical treatment on ROA which, as combined with the results from the bond polarizability analysis, leads to a com...

  5. CARS (Coherent Anti-Stokes Raman Scattering) Spectroscopy of the Reaction Zone of Methane-Nitrous Oxide and RDX Propellant Flames. (United States)


    mospheric pressure--perhaps due to the adsorption by NO2 in the region of the laser beams used in these experiments. Additional experiments are needed (laser...Engineering * ATTN: S. Temkin University Heights Campus New Brunswick, NJ 08903 SRI International ATTN: Technical Library * D. Crosley J. Barker D. Golden G

  6. Emerging Dental Applications of Raman Spectroscopy (United States)

    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.

  7. Raman spectroscopy in high temperature chemistry

    International Nuclear Information System (INIS)

    Drake, M.C.; Rosenblatt, G.M.


    Raman spectroscopy (largely because of advances in laser and detector technology) is assuming a rapidly expanding role in many areas of research. This paper reviews the contribution of Raman spectroscopy in high temperature chemistry including molecular spectroscopy on static systems and gas diagnostic measurements on reactive systems. An important aspect of high temperature chemistry has been the identification and study of the new, and often unusual, gaseous molecules which form at high temperatures. Particularly important is the investigation of vibrational-rotational energy levels and electronic states which determine thermodynamic properties and describe chemical bonding. Some advantages and disadvantages of high temperature Raman spectrosocpy for molecular studies on static systems are compared: (1) Raman vs infrared; (2) gas-phase vs condensed in matries; and (3) atmospheric pressure Raman vs low pressure techniques, including mass spectroscopy, matrix isolation, and molecular beams. Raman studies on molecular properties of gases, melts, and surfaces are presented with emphasis on work not covered in previous reviews of high temperature and matrix isolation Raman spectroscopy

  8. Anti-Stokes shift luminescent materials for bio-applications. (United States)

    Zhu, Xingjun; Su, Qianqian; Feng, Wei; Li, Fuyou


    Anti-Stokes shift luminescence is a special optical process, which converts long-wavelength excitation to short-wavelength emission. This unique ability is especially helpful for bio-applications, because the longer-wavelength light source, usually referring to near infrared light, has a larger penetration depth offering a longer working distance for in vivo applications. The anti-Stokes shift luminescence signal can also be distinguished from the auto-fluorescence of biological tissues, thus reducing background interference during bioimaging. Herein, we summarize recent advances in anti-Stokes shift luminescent materials, including lanthanide and triplet-triplet-annihilation-based upconversion nanomaterials, and newly improved hot-band absorption-based luminescent materials. We focus on the synthetic strategies, optical optimization and biological applications as well as present comparative discussions on the luminescence mechanisms and characteristics of these three types of luminescent materials.

  9. Applications of Raman spectroscopy to gemology. (United States)

    Bersani, Danilo; Lottici, Pier Paolo


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, Matthew W. [Iowa State Univ., Ames, IA (United States)


    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.

  11. CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES: Improved anti-Stokes energy transfer between rare earth ions in Er(0.5)Yb(9.5): FOV oxyfluoride vitroceramics explains the strong color reversal (United States)

    Chen, Xiao-Bo; Wang, Ce; Gregory, Salamo J.; Naruhito, Sawanobori; Kang, Dong-Guo; Masaaki, Ohtsuka; Yang, Guo-Jian; Peng, Fang-Lin


    The widely used energy transfer theory is a foundation of luminescence, in which the rates of Stokes and anti-Stokes processes have the same calculation formula. An improvement on the anti-Stokes energy transfer to explain the fluorescence intensity reversal between the red and green fluorescence of Er(0.5)Yb(9.5):FOV is reported in the present article. The range of the intensity reversal σ was measured to be 877. Dynamic processes for 16 levels were simulated. A coefficient, the improvement factor of the intensity ratio of Stokes to anti-Stokes processes in quantum Raman theory compared to classical Raman theory, is introduced to successfully describe the anti-Stokes energy transfer. A new method to calculate the distance between the rare earth ions, which is critical for the energy transfer calculation, is proposed. The validity of these important improvements is also proved by experiment.

  12. Prospects for in vivo Raman spectroscopy

    International Nuclear Information System (INIS)

    Hanlon, E.B.; Manoharan, R.; Koo, T.-W.; Shafer, K.E.; Motz, J.T.; Fitzmaurice, M.; Kramer, J.R.; Itzkan, I.; Dasari, R.R.; Feld, M.S.


    Raman spectroscopy is a potentially important clinical tool for real-time diagnosis of disease and in situ evaluation of living tissue. The purpose of this article is to review the biological and physical basis of Raman spectroscopy of tissue, to assess the current status of the field and to explore future directions. The principles of Raman spectroscopy and the molecular level information it provides are explained. An overview of the evolution of Raman spectroscopic techniques in biology and medicine, from early investigations using visible laser excitation to present-day technology based on near-infrared laser excitation and charge-coupled device array detection, is presented. State-of-the-art Raman spectrometer systems for research laboratory and clinical settings are described. Modern methods of multivariate spectral analysis for extracting diagnostic, chemical and morphological information are reviewed. Several in-depth applications are presented to illustrate the methods of collecting, processing and analysing data, as well as the range of medical applications under study. Finally, the issues to be addressed in implementing Raman spectroscopy in various clinical applications, as well as some long-term directions for future study, are discussed. (author)

  13. Raman spectroscopy of white wines. (United States)

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


    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. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Triplet State Resonance Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, N. H.; Pagsberg, Palle Bjørn


    Makes the first report on the resonance Raman spectrum of a molecule in its triplet state generated by pulse radiolysis. A solution of 0.01 mol dm-3 of p-terphenyl in benzene was studied......Makes the first report on the resonance Raman spectrum of a molecule in its triplet state generated by pulse radiolysis. A solution of 0.01 mol dm-3 of p-terphenyl in benzene was studied...

  15. Implementation of Deep Ultraviolet Raman Spectroscopy

    DEFF Research Database (Denmark)

    Liu, Chuan

    are located in the visible range, e.g. for petroleum product analysis. Deep Ultraviolet Raman spectroscopy applied to this research field was claimed to be able to solve the problem. Chapter 5 is devoted to gasoline analysis by the use of the DUV Raman spectroscopy. Firstly, some sampling difficulties...... (absorption, condensation) are described. We have found a way to solve the problems, and our solution, using a special designed gas gap cell to obtain measurements of extraordinary high quality, are presented. The DUV Raman spectra of gasoline were excited by three different wavelengths, 257.3, 244.0 and 229...... spectra of the gasoline samples. It is virtually unimportant what the rest of the sample consisted of. The most intense characteristic band is located at 1381 cm-1. The Raman spectra of home-made artificial gasoline mixtures - with gradually increasing Naphthalene contents - can be used to determine...

  16. Compact fibre-based coherent anti-Stokes Raman scattering ...

    Indian Academy of Sciences (India)

    tral compression of femtosecond pulses emitted by a single highly compact fibre laser. Spectral compression of the broadband femtosecond pulses is achieved by generating narrow-band second harmonic (SH) pulses in crystals with large group- delay mismatch between the fundamental frequency (FF) and the SH pulses ...

  17. Application of Raman spectroscopy for cancer diagnosis

    International Nuclear Information System (INIS)

    Krishnakumar, N.


    Cancer is the second leading causes of death next to heart diseases, Half of all cancer cases occur in developing countries. The conventional histopathology is usually the most trustable gold standard for pre-cancer and cancer diagnosis. However, the applicability of this method is more or less restricted because of the requirement of removing human tissues and the difficulty of real time diagnosis. Recently, there has been increased interest in 'optical biopsy' system using tissue spectroscopy to establish the pathological changes. Among optical based methods, Raman spectroscopy is a unique vibrational spectroscopic technique capable of probing biomolecular structures and conformation of tissues, and has excelled in the early detection of pre-cancer and cancer in the number of organs with high diagnostic specificity. Raman spectroscopy offers certain distinct advantages over than other optical diagnostic techniques such as high spatial resolution, use of less harmful NIR radiation, less or no sample preparation, no influence of water bands which facilitates in vivo/in situ measurements. This makes Raman spectroscopy also very useful for biomedical applications. Several research groups have demonstrated the efficacy of this technique in biomedical applications. The background and principle of these techniques will be discussed with some examples and discussions on how Raman spectroscopy can act as a promising technique for rapid in vivo diagnosis and detection of various cancers at the molecular level. (author)

  18. Visualizing cell state transition using Raman spectroscopy.

    Directory of Open Access Journals (Sweden)

    Taro Ichimura

    Full Text Available System level understanding of the cell requires detailed description of the cell state, which is often characterized by the expression levels of proteins. However, understanding the cell state requires comprehensive information of the cell, which is usually obtained from a large number of cells and their disruption. In this study, we used Raman spectroscopy, which can report changes in the cell state without introducing any label, as a non-invasive method with single cell capability. Significant differences in Raman spectra were observed at the levels of both the cytosol and nucleus in different cell-lines from mouse, indicating that Raman spectra reflect differences in the cell state. Difference in cell state was observed before and after the induction of differentiation in neuroblastoma and adipocytes, showing that Raman spectra can detect subtle changes in the cell state. Cell state transitions during embryonic stem cell (ESC differentiation were visualized when Raman spectroscopy was coupled with principal component analysis (PCA, which showed gradual transition in the cell states during differentiation. Detailed analysis showed that the diversity between cells are large in undifferentiated ESC and in mesenchymal stem cells compared with terminally differentiated cells, implying that the cell state in stem cells stochastically fluctuates during the self-renewal process. The present study strongly indicates that Raman spectral morphology, in combination with PCA, can be used to establish cells' fingerprints, which can be useful for distinguishing and identifying different cellular states.

  19. Raman spectroscopy of saliva as a perspective method for periodontitis diagnostics Raman spectroscopy of saliva (United States)

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


    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.

  20. Characterization of Kevlar Using Raman Spectroscopy (United States)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor


    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.

  1. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, S.; Xiao, Sanshui


    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (10(10)). (C) 2012 Optical Society of America...

  2. Surface-enhanced Raman spectroscopy: nonlocal limitations

    DEFF Research Database (Denmark)

    Toscano, Giuseppe; Raza, Søren; Xiao, Sanshui


    for our understanding of surface-enhanced Raman spectroscopy (SERS). The intrinsic length scale of the electron gas serves to smear out assumed field singularities, leaving the SERS enhancement factor finite, even for geometries with infinitely sharp features. For silver nanogroove structures, mimicked...... by periodic arrays of half-cylinders (up to 120 nm in radius), we find no enhancement factors exceeding 10 orders of magnitude (1010)....

  3. Candida parapsilosis Biofilm Identification by Raman Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Samek, Ota; Mlynariková, K.; Bernatová, Silvie; Ježek, Jan; Krzyžánek, Vladislav; Šiler, Martin; Zemánek, Pavel; Růžička, F.; Holá, Miroslava; Mahelová, M.


    Roč. 15, č. 12 (2014), s. 23924-23935 E-ISSN 1422-0067 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01; GA ČR GAP205/11/1687 Institutional support: RVO:68081731 Keywords : Raman spectroscopy * Candida parapsilosis * biofilm Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.862, year: 2014

  4. Raman spectroscopy as a tool for investigating lipid protein interactions

    DEFF Research Database (Denmark)

    Petersen, Frederic Nicolas Rønne; Helix Nielsen, Claus


    Raman spectroscopy is a very well-established technique for noninvasive probing of chemical compounds. The fad that Raman scattering is an inherently weak effect has prompted many new developments in sample signal enhancement and techniques (such as surface-enhancement Raman spectroscopy [SERS]) ...

  5. Detection of biologically active diterpenoic acids by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Talian, Ivan; Orinak, Andrej; Efremov, Evtim V.


    is not suitable for their unambiguous identification, especially not in solution. We attempted to increase the sensitivity by applying UV-resonance Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) techniques. The UV-Raman spectra of the three compounds in ethanol/water 50 : 50 showed only very......Three poorly detectable, biologically active diterpenoic acids, kaurenoic, abietic, and gibberellic acid, were studied by using different modes of Raman spectroscopy. Because of their structural similarities, in the absence of strongly polarizable groups, conventional Raman spectroscopy...

  6. Transcutaneous Raman Spectroscopy of Murine Bone In Vivo


    Schulmerich, Matthew V.; Cole, Jacqueline H.; Kreider, Jaclynn M.; Esmonde-White, Francis; Dooley, Kathryn A.; Goldstein, Steven A.; Morris, Michael D.


    Raman spectroscopy can provide valuable information about bone tissue composition in studies of bone development, biomechanics, and health. In order to study the Raman spectra of bone in vivo, instrumentation that enhances the recovery of subsurface spectra must be developed and validated. Five fiber-optic probe configurations were considered for transcutaneous bone Raman spectroscopy of small animals. Measurements were obtained from the tibia of sacrificed mice, and the bone Raman signal was...

  7. Dynamic characterization of MEMS using Raman spectroscopy

    International Nuclear Information System (INIS)

    Hu, Z X; Hedley, J; Gallacher, B J; Arce-Garcia, I


    This paper reports on utilizing Raman spectroscopy to characterize the motion and measure strain levels in dynamic micromechanical structures. The main advantages of such a technique is that surface features are not required to characterize the 3D motion as the crystal lattice is used as the reference frame and that it is suited to high frequency measurements. Two methodologies are presented. The first utilizes a strobed diode laser probe beam with the centre position of the Raman peak giving a measure of strain as a function of phase. A measurement resolution of 210 µstrain is obtained at frequencies up to 100 kHz. The second method uses a HeNe laser probe beam with the broadening of the Raman peak, indicating strain levels. Although no phase data are available in the latter technique, the technique is rapid and may be utilized on a Raman system without any modification. A measurement resolution of 30 µstrain is achieved and strain mapping of a region may be performed within minutes. As strobing is not used here, the technique is not frequency limited. Comparisons with alternative optical characterization techniques are made

  8. Construction of coherent antistokes Raman spectroscopy (CARS)

    International Nuclear Information System (INIS)

    Zidan, M. D.; Jazmati, A.


    Coherent Antistokes Raman Spectroscopy (CARS) has been built. It consists of a Raman cell, which is filled with CO 2 gas at 5 atm pressure and a frequency doubled Nd-YAG laser pumped dye laser. The two beams are focused by means of a bi-convex lens into Raman cell. The Antistokes signals (CARS signals) are generated due to Four-wave mixing process. The antistokes signals were directed to monochrometer entrance slit by prism . The signals are detected by photomultiplier detector which is fixed on the exit slit and connected to data acquisition card located inside the computed case. The dye laser frequency has to be tuned to satisfy the energy difference between the ν 1 beam (Nd- YAG laser beam) and the ν 2 beam (the stokes beam or the dye laser beam) exactly corresponds to a vibrational - rotational Raman resonance (ν 2 - ν 1 = ν M ) in the 12 CO 2 or 13 CO 2 molecule, then the antistokes signals (ν 3 ) will be generated. The spectra of the CARS signals have been recorded to determine the isotope shift of 12 CO 2 , 13 CO 2 , which is 18.3 cm -1 . (author)

  9. Raman spectroscopy in cervical cancers: An update

    Directory of Open Access Journals (Sweden)

    S Rubina


    Full Text Available Cervical cancer is the third most common cancer among women worldwide. Developing countries contribute more than 80% towards global burden. Over the last 2 decades, Raman spectroscopy (RS has been actively pursued for cervical cancer detection. In view of latest development in Raman spectroscopic applications in cervical cancers, especially in vivo studies, an update of the same is presented in this article. This articles opens with a brief note on Anatomy of cervix followed by Etiology, and conventional Screening and Diagnosis of Cervical cancers. In subsequent sections, brief description of Theory and Instrumentation of RS is followed by a review of recent developments in cervical cancer detection; with emphasis on cell lines, exfoliated cells, ex vivo and in vivo, and therapeutic response monitoring applications in cervical cancer.

  10. Spectroscopy and Raman imaging of inhomogeneous materials

    International Nuclear Information System (INIS)

    Maslova, Olga


    This thesis is aimed at developing methodologies in Raman spectroscopy and imaging. After reviewing the statistical instruments which allow treating giant amount of data (multivariate analysis and classification), the study is applied to two families of well-known materials which are used as models for testing the limits of the implemented developments. The first family is a series of carbon materials pyrolyzed at various temperatures and exhibiting inhomogeneities at a nm scale which is suitable for Raman-X-ray diffraction combination. Another results concern the polishing effect on carbon structure. Since it is found to induce Raman artifacts leading to the overestimation of the local structural disorder, a method based on the use of the G band width is therefore proposed in order to evaluate the crystallite size in both unpolished and polished nano-graphites. The second class of materials presents inhomogeneities at higher (micrometric) scales by the example of uranium dioxide ceramics. Being well adapted in terms of spatial scale, Raman imaging is thus used for probing their surfaces. Data processing is implemented via an approach combining the multivariate (principal component) analysis and the classical fitting procedure with Lorentzian profiles. The interpretation of results is supported via electron backscattering diffraction (EBSD) analysis which enables us to distinguish the orientation effects of ceramic grains from other underlying contributions. The last ones are mainly localized at the grain boundaries, that is testified by the appearance of a specific Raman mode. Their origin seems to be caused by stoichiometric oxygen variations or impurities, as well as strain inhomogeneities. The perspectives of this work include both the implementation of other mathematical methods and in-depth analysis of UO 2 structure damaged by irradiation (anisotropic effects, role of grain boundaries). (author) [fr

  11. Super-Resolution Raman Spectroscopy by Digital Image Processing


    Tomita, Motohiro; Hashiguchi, Hiroki; Yamaguchi, Takuya; Takei, Munehisa; Kosemura, Daisuke; Ogura, Atsushi


    We demonstrate the results of a strain (stress) evaluation obtained from Raman spectroscopy measurements with the super-resolution method (the so-called super-resolution Raman spectroscopy) for a Si substrate with a patterned SiN film (serving as a strained Si sample). To improve the spatial resolution of Raman spectroscopy, we used the super-resolution method and a high-numerical-aperture immersion lens. Additionally, we estimated the spatial resolution by an edge force model (EFM) calculati...

  12. Simultaneous Conoscopic Holography and Raman Spectroscopy (United States)

    Schramm, Harry F.; Kaiser, Bruce


    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

  13. Rapid identification of staphylococci by Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Rebrošová, K.; Šiler, Martin; Samek, Ota; Růžička, F.; Bernatová, Silvie; Holá, V.; Ježek, Jan; Zemánek, Pavel; Sokolová, J.; Petráš, P.


    Roč. 7, NOV (2017), s. 1-8, č. článku 14846. ISSN 2045-2322 R&D Projects: GA ČR(CZ) GA15-20645S; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : coagulase-negative staphylococci * Raman spectroscopy * rapid identification Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 4.259, year: 2016

  14. Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy. (United States)

    Tenne, D A; Bruchhausen, A; Lanzillotti-Kimura, N D; Fainstein, A; Katiyar, R S; Cantarero, A; Soukiassian, A; Vaithyanathan, V; Haeni, J H; Tian, W; Schlom, D G; Choi, K J; Kim, D M; Eom, C B; Sun, H P; Pan, X Q; Li, Y L; Chen, L Q; Jia, Q X; Nakhmanson, S M; Rabe, K M; Xi, X X


    We demonstrated that ultraviolet Raman spectroscopy is an effective technique to measure the transition temperature (Tc) in ferroelectric ultrathin films and superlattices. We showed that one-unit-cell-thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are not only ferroelectric (with Tc as high as 250 kelvin) but also polarize the quantum paraelectric SrTiO3 layers adjacent to them. Tc was tuned by approximately 500 kelvin by varying the thicknesses of the BaTiO3 and SrTiO3 layers, revealing the essential roles of electrical and mechanical boundary conditions for nanoscale ferroelectricity.

  15. UTI diagnosis and antibiogram using Raman spectroscopy (United States)

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


    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.

  16. Disease recognition by infrared and Raman spectroscopy. (United States)

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


    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. ((c) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).

  17. Picosecond anti-Stokes generation in a photonic-crystal fiber for interferometric CARS microscopy

    DEFF Research Database (Denmark)

    Andresen, Esben Ravn


    We generate tunable picosecond anti-Stokes pulses by four-wave mixing of two picosecond pump and Stokes pulse trains in a photonic-crystal fiber. The visible, spectrally narrow anti-Stokes pulses with shifts over 150 nm are generated without generating other spectral features. As a demonstration,...

  18. Operando Raman Micro Spectroscopy of Polymer Electrolyte Fuel Cells (United States)


    exchange site local symmetry. © The Author(s) 2016. Published by ECS. This is an open access article distributed under the terms of the Creative Commons...Operando Raman spectroscopy.—All operando Raman spectra were acquired using a WITec Inc. (Ulm, Germany) Confocal Raman Microscope ( CRM 200). A 488

  19. In vivo Raman spectroscopy of cervix cancers (United States)

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


    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.

  20. Determining the Authenticity of Gemstones Using Raman Spectroscopy (United States)

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


    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.

  1. Scanning Angle Raman spectroscopy in polymer thin film characterization

    Energy Technology Data Exchange (ETDEWEB)

    Nguyen, Vy H.T. [Iowa State Univ., Ames, IA (United States)


    The focus of this thesis is the application of Raman spectroscopy for the characterization of thin polymer films. Chapter 1 provides background information and motivation, including the fundamentals of Raman spectroscopy for chemical analysis, scanning angle Raman scattering and scanning angle Raman scattering for applications in thin polymer film characterization. Chapter 2 represents a published manuscript that focuses on the application of scanning angle Raman spectroscopy for the analysis of submicron thin films with a description of methodology for measuring the film thickness and location of an interface between two polymer layers. Chapter 3 provides an outlook and future directions for the work outlined in this thesis. Appendix A, contains a published manuscript that outlines the use of Raman spectroscopy to aid in the synthesis of heterogeneous catalytic systems. Appendix B and C contain published manuscripts that set a foundation for the work presented in Chapter 2.

  2. Quantitative aspects of near-infrared Fourier transform Raman spectroscopy (United States)

    Walder, F. T.; Smith, M. J.

    Three fundamental behaviors of vibrational spectroscopy data manipulation routinely associated with Fourier transform infrared (FTIR) spectroscopy are evaluated for near-infrared (NIR) Fourier transform Raman spectroscopy. Spectral reproducibility, spectral subtraction and sensitivity are examined relative to the NIR FT-Raman experiment. Quantitative predictive ability is compared for identical sets of samples containing mixtures of the three xylene isomers. Partial least-squares analysis is used to compare predictive ability. IR performance is found to be better than Raman, though the potential for method development using NIR FT-Raman is shown to be quite promising.

  3. Resonant Raman spectroscopy on InN

    International Nuclear Information System (INIS)

    Kuball, M.; Pomeroy, J.W.; Wintrebert-Fouquet, M.; Butcher, K.S.A.; Lu, Hai; Schaff, W.J.; Shubina, T.V.; Ivanov, S.V.; Vasson, A.; Leymarie, J.


    The novel use of resonant Raman spectroscopy to elucidate the band gap of InN is illustrated in a study of MBE-grown films. This technique can distinguish between electronic transitions related to the InN from transitions related to defects and impurities that are so typical for current InN material. Using excitation energies from 1.49 eV (830 nm) to 2.54 eV (488 nm), we identify a critical point in the InN band structure within ∼200-300 meV below 1.5 eV. The origin of this critical point, whether band gap or higher critical point, is discussed. Furthermore, Raman results are presented on the temperature dependence of the InN phonons. Analysis of the data provides information on phonon lifetimes and decay mechanisms, important to assess whether hot phonon effects need to be considered in future InN devices. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Skin biochemical composition analysis by Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Patricia Karen; Tosato, Maira Gaspar; Alves, Rani de Souza; Martin, Airton Abrahao; Favero, Priscila Pereira; Raniero, Leandro, E-mail: [Laboratorio de Espectroscopia Vibracional Biomedica, Instituto de Pesquisa e Desenvolvimento - IP e D, Universidade do Vale do Paraiba - UniVap, Sao Jose dos Campos, SP (Brazil)


    Skin aging is characterized by cellular and molecular alterations. In this context, Confocal Raman spectroscopy was used in vivo to measure these biochemical changes as function of the skin depth. In this study we have tried to correlate spectra from pure amino acids to in vivo spectra from volunteers with different ages. This study was performed on 32 volunteers: 11 from Group A (20-23 years), 11 from Group B (39-42 years) and 10 from Group C (59-62 years). For each group, the Raman spectra were measured on the surface (0 mm), 30 +- 3 mm and 60 +- 3 {mu}m below the surface. The results from intergroup comparisons showed that the oldest group had a prevalence of the tyrosine band, but it also presented a decrease in the band centered at 875 cm{sup -1} of pyrrolidone acid. The amide I band centered at 1637 cm{sup -1} that is attributed to collagen, as well as other proteins and lipid, showed a smaller amount of these biomolecules for Group C, which can be explained by the decrease in collagen concentration as a function of age. (author)

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

    Directory of Open Access Journals (Sweden)

    Brandon Redding


    Full Text Available 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.

  6. Raman spectroscopy of human saliva for acute myocardial infarction detection (United States)

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


    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.

  7. In-situ plasmon-driven chemical reactions revealed by high vacuum tip-enhanced Raman spectroscopy. (United States)

    Sun, Mengtao; Zhang, Zhenglong; Zheng, Hairong; Xu, Hongxing


    With strong surface plasmons excited at the metallic tip, tip-enhanced Raman spectroscopy (TERS) has both high spectroscopic sensitivity and high spatial resolution, and is becoming an essential tool for chemical analysis. It is a great challenge to combine TERS with a high vacuum system due to the poor optical collection efficiency. We used our innovatively designed home-built high vacuum TERS (HV-TERS) to investigate the plasmon-driven in-situ chemical reaction of 4-nitrobenzenethiol dimerizing to dimercaptoazobenzene. The chemical reactions can be controlled by the plasmon intensity, which in turn can be controlled by the incident laser intensity, tunneling current and bias voltage. The temperature of such a chemical reaction can also be obtained by the clearly observed Stokes and Anti-Stokes HV-TERS peaks. Our findings offer a new way to design a highly efficient HV-TERS system and its applications to chemical catalysis and synthesis of molecules, and significantly extend the studies of chemical reactions.

  8. Raman spectroscopy for cancer detection and characterization in metastasis models (United States)

    Koga, Shigehiro; Oshima, Yusuke; Sato, Mitsunori; Ishimaru, Kei; Yoshida, Motohira; Yamamoto, Yuji; Matsuno, Yusuke; Watanabe, Yuji


    Raman spectroscopy provides a wealth of diagnostic information to the surgeon with in situ cancer detection and label-free histopathology in clinical practice. Raman spectroscopy is a developing optical technique which can analyze biological tissues with light scattering. The difference in frequencies between the incident light and the scattering light are called Raman shifts, which correspond to the vibrational energy of the molecular bonds. Raman spectrum gives information about the molecular structure and composition in biological specimens. We had been previously reported that Raman spectroscopy could distinguish various histological types of human lung cancer cells from normal cells in vitro. However, to identify and detect cancer diagnostic biomarkers in vivo on Raman spectroscopy is still challenging, because malignancy can be characterized not only by the cancer cells but also by the environmental factors including immune cells, stroma cells, secretion vesicles and extracellular matrix. Here we investigate morphological and molecular dynamics in both cancer cells and their environment in xenograft models and spontaneous metastasis models using Raman spectroscopy combined with fluorescence microscopy and photoluminescence imaging. We are also constructing a custom-designed Raman spectral imaging system for both in vitro and in vivo assay of tumor tissues to reveal the metastasis process and to evaluate therapeutic effects of anti-cancer drugs and their drug delivery toward the clinical application of the technique.

  9. Periodontitis diagnostics using resonance Raman spectroscopy on saliva (United States)

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


    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.

  10. Periodontitis diagnostics using resonance Raman spectroscopy on saliva

    International Nuclear Information System (INIS)

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


    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. (letter)

  11. Super-Resolution Raman Spectroscopy by Digital Image Processing

    Directory of Open Access Journals (Sweden)

    Motohiro Tomita


    Full Text Available We demonstrate the results of a strain (stress evaluation obtained from Raman spectroscopy measurements with the super-resolution method (the so-called super-resolution Raman spectroscopy for a Si substrate with a patterned SiN film (serving as a strained Si sample. To improve the spatial resolution of Raman spectroscopy, we used the super-resolution method and a high-numerical-aperture immersion lens. Additionally, we estimated the spatial resolution by an edge force model (EFM calculation. One- and two-dimensional stress distributions in the Si substrate with the patterned SiN film were obtained by super-resolution Raman spectroscopy. The results from both super-resolution Raman spectroscopy and the EFM calculation were compared and were found to correlate well. The best spatial resolution, 70 nm, was achieved by super-resolution Raman measurements with an oil immersion lens. We conclude that super-resolution Raman spectroscopy is a useful method for evaluating stress in miniaturized state-of-the-art transistors, and we believe that the super-resolution method will soon be a requisite technique.

  12. Investigation of biomineralization by Raman spectroscopy (United States)

    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

  13. Application of Raman spectroscopy to forensic fibre cases. (United States)

    Lepot, L; De Wael, K; Gason, F; Gilbert, B


    Five forensic fibre cases in which Raman spectroscopy proved to be a good complementary method for microspectrophotometry (MSP) are described. Absorption spectra in the visible range are indeed sometimes characteristic ofa certain dye but this one can be subsequently identified unambiguously by Raman spectroscopy using a spectral library. In other cases the comparison of Raman spectra of reference fibres and suspect fibres led to an improvement of the discrimination power. The Raman measurements have been performed directly on mounted fibres and the spectra showed only little interference from the mounting resin and glass. Raman spectroscopy is therefore a powerful method that can be applied in routine fibre analysis following optical microscopy and MSP measurements.

  14. Rationale for single molecule detection by means of Raman spectroscopy

    International Nuclear Information System (INIS)

    Gaponenko, S.V.; Guzatov, D.V.


    A consistent quantum electrodynamical description is proposed of Raman scattering of light by a molecule in a medium with a modified photon density of states. Enhanced local density of states near a metal nanobody is shown to increase a scattering rate by several orders of magnitude, thus providing a rationale for experimental detection of single molecules by means of Raman spectroscopy. For an ellipsoidal particle 10 14 -fold enhancement of the Raman scattering cross-section is obtained. (authors)

  15. Strain characterization of FinFETs using Raman spectroscopy

    NARCIS (Netherlands)

    Kaleli, B.; van Hemert, T.; Hueting, Raymond Josephus Engelbart; Wolters, Robertus A.M.


    Metal induced strain in the channel region of silicon (Si) fin-field effect transistor (FinFET) devices has been characterized using Raman spectroscopy. The strain originates from the difference in thermal expansion coefficient of Si and titanium-nitride. The Raman map of the device region is used

  16. Characterisation of Oil-Gas Mixtures by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan


    . The present project deals with development of a technique for quick analysis of oil-gas mixtures. The main emphasis is laid on characterisation of gas phases in equilibrium with oil at high pressures and high temperatures by Raman spectroscopy. The Raman technique has a great potential of being useful, due...

  17. Continuous gradient temperature Raman spectroscopy of unsaturated fatty acids (United States)

    A new innovative technique gradient temperature, Raman spectroscopy (GTRS), identifies Raman frequency shifts in solid or liquid samples, and correlates them with specific temperature ranges within which flexible structures absorb heat. GTRS can easily detect changes that occur within one celcius te...

  18. Raman spectroscopy of CNC-and CNF-based nanocomposites (United States)

    Umesh P. Agarwal


    In this chapter, applications of Raman spectroscopy to nanocelluloses and nanocellulose composites are reviewed, and it is shown how use of various techniques in Raman can provide unique information. Some of the most important uses consisted of identification of cellulose nanomaterials, estimation of cellulose crystallinity, study of dispersion of cellulose...

  19. Fast Resonance Raman Spectroscopy of Short-Lived Radicals

    DEFF Research Database (Denmark)

    Pagsberg, Palle Bjørn; Wilbrandt, Robert Walter; Hansen, Karina Benthin


    We report the first application of pulsed resonance Raman spectroscopy to the study of short-lived free radicals produced by pulse radiolysis. A single pulse from a flash-lamp pumped tunable dye laser is used to excite the resonance Raman spectrum of the p-terphenyl anion radical with an initial...

  20. Surface-Enhanced Raman Spectroscopy for Heterogeneous Catalysis Research

    NARCIS (Netherlands)

    Harvey, C.E.


    Raman spectroscopy is valuable characterization technique for the chemical analysis of heterogeneous catalysts, both under ex-situ and in-situ conditions. The potential for Raman to shine light on the chemical bonds present in a sample makes the method highly desirable for detailed catalyst

  1. Component Identification in Multi-Chemical Mixtures With Swept-Wavelength Resonant-Raman Spectroscopy (United States)


    03-2011 Journal Article Component Identification in Multi-Chemical Mixtures with Swept-Wavelength Resonant-Raman Spectroscopy Robert Lunsford, David...IDENTIFICATION IN MULTI-CHEMICAL MIXTURES WITH SWEPT-WAVELENGTH RESONANT-RAMAN SPECTROSCOPY Robert Lunsford1, David Gillis2, Jacob Grun1, Pratima...fractional molecular abundances. Introduction The utilization of Raman spectroscopy , specifically Ultraviolet Resonance Raman spectroscopy for

  2. Developing Raman spectroscopy for the nondestructive testing of composite materials. (United States)


    The proposed research will develop the application of Raman Spectroscopy as a nondestructive evaluation tool for the condition assessment of carbon fiber composites. Composite materials are increasingly being used in engineered structures and compone...

  3. [Identification of B jade by Raman spectroscopy]. (United States)

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


    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.

  4. [Surface-enhanced Raman spectroscopy analysis of thiabendazole pesticide]. (United States)

    Lin, Lei; Wu, Rui-mei; Liu, Mu-hua; Wang, Xiao-bin; Yan, Lin-yuan


    Surface-enhanced Raman spectroscopy (SERS) technique was used to analyze the Raman peaks of thiabendazole pesticides in the present paper. Surface enhanced substrates of silver nanoparticle were made based on microwave technology. Raman signals of thiabendazole were collected by laser Micro-Raman spectrometer with 514. 5 and 785 nm excitation wavelengths, respectively. The Raman peaks at different excitation wavelengths were analyzed and compared. The Raman peaks 782 and 1 012 at 785 nm excitation wavelength were stronger, which were C--H out-of-plane vibrations. While 1284, 1450 and 1592 cm(-1) at 514.5 nm excitation wavelength were stronger, which were vng and C==N stretching. The study results showed that the intensity of Raman peak and Raman shift at different excitation wavelengths were different And strong Raman signals were observed at 782, 1012, 1284, 1450 and 1592 cm(-1) at 514.5 and 785 nm excitation wavelengths. These characteristic vibrational modes are characteristic Raman peaks of carbendazim pesticide. The results can provide basis for the rapid screening of pesticide residue in agricultural products and food based on Raman spectrum.

  5. Micro-Raman spectroscopy for meat type detection (United States)

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


    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.

  6. Raman spectroscopy in the analysis of food and pharmaceutical nanomaterials

    Directory of Open Access Journals (Sweden)

    Ying-Sing Li


    Full Text Available Raman scattering is an inelastic phenomenon. Although its cross section is very small, recent advances in electronics, lasers, optics, and nanotechnology have made Raman spectroscopy suitable in many areas of application. The present article reviews the applications of Raman spectroscopy in food and drug analysis and inspection, including those associated with nanomaterials. Brief overviews of basic Raman scattering theory, instrumentation, and statistical data analysis are also given. With the advent of Raman enhancement mechanisms and the progress being made in metal nanomaterials and nanoscale metal surfaces fabrications, surface enhanced Raman scattering spectroscopy has become an extra sensitive method, which is applicable not only for analysis of foods and drugs, but also for intracellular and intercellular imaging. A Raman spectrometer coupled with a fiber optics probe has great potential in applications such as monitoring and quality control in industrial food processing, food safety in agricultural plant production, and convenient inspection of pharmaceutical products, even through different types of packing. A challenge for the routine application of surface enhanced Raman scattering for quantitative analysis is reproducibility. Success in this area can be approached with each or a combination of the following methods: (1 fabrication of nanostructurally regular and uniform substrates; (2 application of statistic data analysis; and (3 isotopic dilution.

  7. Micro-Raman spectroscopy on oral tissues (United States)

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


    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.

  8. Cutaneous porphyrins exhibit anti-stokes fluorescence that is detectable in sebum (Conference Presentation) (United States)

    Tian, Giselle; Zeng, Haishan; Zhao, Jianhua; Wu, Zhenguo; Al Jasser, Mohammed; Lui, Harvey; Mclean, David I.


    Porphyrins produced by Propionibacterium acnes represent the principal fluorophore associated with acne, and appear as orange-red luminescence under the Wood's lamp. Assessment of acne based on Wood's lamp (UV) or visible light illumination is limited by photon penetration depth and has limited sensitivity for earlier stage lesions. Inducing fluorescence with near infrared (NIR) excitation may provide an alternative way to assess porphyrin-related skin disorders. We discovered that under 785 nm CW laser excitation PpIX powder exhibits fluorescence emission in the shorter wavelength range of 600-715 nm with an intensity that is linearly dependent on the excitation power. We attribute this shorter wavelength emission to anti-Stokes fluorescence. Similar anti-Stokes fluorescence was also detected focally in all skin-derived samples containing porphyrins. Regular (Stokes) fluorescence was present under UV and visible light excitation on ex vivo nasal skin and sebum from uninflamed acne, but not on nose surface smears or sebum from inflamed acne. Co-registered CW laser-excited anti-Stokes fluorescence and fs laser-excited multi-photon fluorescence images of PpIX powder showed similar features. In the skin samples because of the anti-Stokes effect, the NIR-induced fluorescence was presumably specific for porphyrins since there appeared to be no anti-Stokes emission signals from other typical skin fluorophores such as lipids, keratins and collagen. Anti-Stokes fluorescence under NIR CW excitation is more sensitive and specific for porphyrin detection than UV- or visible light-excited regular fluorescence and fs laser-excited multi-photon fluorescence. This approach also has higher image contrast compared to NIR fs laser-based multi-photon fluorescence imaging. The anti-Stokes fluorescence of porphyrins within sebum could potentially be applied to detecting and targeting acne lesions for treatment via fluorescence image guidance.

  9. Identification of color development potential of quartz by Raman spectroscopy

    International Nuclear Information System (INIS)

    Alkmim, Danielle G.; Lameiras, Fernando S.; Almeida, Frederico O.T.


    Colorless quartz is usually exposed to ionizing radiation (gamma rays or high energy electron beams) to acquire different colors for jewelry. Color development is due to the presence of traces of some elements such as aluminum, iron, hydrogen, lithium, or sodium. Most quartz crystals are extracted colorless from nature and it is necessary to separate those that can develop colors from those that cannot. Irradiation tests can be used to accomplish this separation, but they take a long time. Infrared signature of colorless quartz can also be used. However, infrared spectroscopy is quite expensive, especially when using portable devices. Raman spectroscopy is now available as an inexpensive and portable technique that could provide identification of the samples of colorless quartz still in the field, facilitating the prediction for their economic exploitation. In addition, Raman spectroscopy usually requires a minimum or no sample preparation. This paper presents an investigation of the feasibility of using Raman spectroscopy as a substitute for infrared spectroscopy to predict the potential for color development of quartz. A band at 3595 cm -1 in the Raman shift spectrum was observed only along the c axis of a prasiolite excited by a high power 514 nm laser. This band was not observed in quartz samples that do not develop color after irradiation. Further studies are required to identify the potential for color development by Raman spectroscopy of other types of colorless quartz. (author)

  10. Surface enhanced raman spectroscopy on chip

    DEFF Research Database (Denmark)

    Hübner, Jörg; Anhøj, Thomas Aarøe; Zauner, Dan


    In this paper we report low resolution surface enhanced Raman spectra (SERS) conducted with a chip based spectrometer. The flat field spectrometer presented here is fabricated in SU-8 on silicon, showing a resolution of around 3 nm and a free spectral range of around 100 nm. The output facet...... fiber. The obtained spectra show that chip based spectrometer together with the SERS active surface can be used as Raman sensor....


    Directory of Open Access Journals (Sweden)

    I. M. Sevastianova


    Full Text Available Subject of Research.The paper deals with study of Raman spectra and luminescence spectra in the visible region of the sodium-germanate glass: 49 GeO2 – 13 Na2O – 27 Yb2O3 – 11 La2O3 - 0,25 Er2O3 and presents research results. In addition, this glass is doped with 5 mol% of the following components MgO, BaO, Al2O3, PbO, Nb2O5, TiO2, SiO2, P2O5 in order to study the effect of these additives on the structure of the glassy matrix and the anti-Stokes luminescence spectra of erbium ions. Method. Raman scatteringspectra were recorded by Renishaw inVia Raman Microscope. Excitation source is a helium neon laser (λ= 633 nm with power equal to 50Wt. Anti-Stokes luminescence of erbium ions was registered in spectral region of 450–750 nm at room temperature (excitation laser wavelength is 975 nm, power is 1Wt. Main Results. It was shown that the structure of the initial glass does not change with the introduction of niobium as Nb2O5 in any coordination plays a role of network forming, building a single mixed grid with tetrahedrons [GeO4]. Introduction of the second glass former P2O5 leads to loosening germanate structure due to the appearance of the phosphate sublattice. This leads to a redistribution of the relative intensity of up-conversion luminescence bands with maxima at 540 and 670 nm compared with the initial glass. Introduction of additives PbO, MgO, Al2O3, TiO2 results in a multicenter structure. In case of titanium oxide addition it leads to a change in the relative intensities of the erbium luminescence.

  12. Evaluation of thyroid tissue by Raman spectroscopy (United States)

    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.


    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

  13. Corrosion product characterisation by fibre optic raman spectroscopy

    International Nuclear Information System (INIS)

    Guzonas, D.A.; Rochefort, P.A.; Turner, C.W.


    Fibre optic Raman spectroscopy has been used to characterise secondary-side deposits removed from CANDU steam generators. The deposits examined were in the form of powders, millimetre-sized flakes, and deposits on the surfaces of pulled steam generator tubes. The compositions of the deposits obtained using Raman spectroscopy are similar to the compositions obtained using other ex-situ analytical techniques. A semi-quantitative estimate of amounts of the major components can be obtained from the spectra. It was noted that the signal-to-noise ratio of the Raman spectra decreased as the amount of magnetite in the deposit increased, as a result of absorption of the laser light by the magnetite. The conversion of magnetite to hematite by the laser beam was observed when high laser powers were used. The Raman spectra of larger flake samples clearly illustrate the inhomogeneous nature of the deposits. (author)

  14. Surface enhanced raman spectroscopy analytical, biophysical and life science applications

    CERN Document Server

    Schlücker, Sebastian


    Covering everything from the basic theoretical and practical knowledge to new exciting developments in the field with a focus on analytical and life science applications, this monograph shows how to apply surface-enhanced Raman scattering (SERS) for solving real world problems. From the contents: * Theory and practice of SERS * Analytical applications * SERS combined with other analytical techniques * Biophysical applications * Life science applications including various microscopies Aimed at analytical, surface and medicinal chemists, spectroscopists, biophysicists and materials scientists. Includes a Foreword by the renowned Raman spectroscopist Professor Wolfgang Kiefer, the former Editor-in-Chief of the Journal of Raman Spectroscopy.

  15. Raman spectroscopy and X-ray diffraction studies on celestite

    International Nuclear Information System (INIS)

    Chen Yenhua; Yu Shucheng; Huang, Eugene; Lee, P.-L.


    High-pressure Raman spectroscopy and X-ray diffraction studies of celestite (SrSO 4 ) were carried out in a diamond anvil cell at room temperature. Variation in the Raman vibrational frequency and change of lattice parameters with pressure indicate that a transformation occurs in celestite. This transformation caused an adjustment in the Sr-O polyhedra that affected the stretching-force constant of SO 4 . Moreover, compressibilities along the crystallographic axes decreased in the order a to c to b. From the compression data, the bulk modulus of the celestite was 87 GPa. Both X-ray and Raman data show that the transition in celestite is reversible.

  16. Raman Spectroscopy of Isotactic Polypropylene-Halloysite Nanocomposites

    Directory of Open Access Journals (Sweden)

    Elamin E. Ibrahim


    Full Text Available Raman spectroscopy investigations on nanocomposites obtained by dispersing halloysite within isotactic polypropylene are reported. A detailed analysis of the modifications of the regularity band associated to the polymeric matrix is presented. The Raman lines assigned to the polymeric matrix are broadened and weakened as the loading with halloysite is increased. The analysis of Raman lines indicates that the polymeric matrix becomes less crystalline upon the loading with halloysite and that the nanofiller is experiencing a weak dehydration upon dispersion within the polymeric matrix, probably due to the related thermal processing used to achieve the dispersion of halloysite.

  17. Potential of Raman and Infrared Spectroscopy for Plant Analysis (United States)

    Schulz, H.


    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.

  18. Characterization of oil-producing microalgae using Raman spectroscopy (United States)

    Samek, O.; Zemánek, P.; Jonáš, A.; Telle, H. H.


    Raman spectroscopy offers a powerful alternative analytical method for the detection and identification of lipids/oil in biological samples, such as algae and fish. Recent research in the authors' groups, and experimental data only very recently published by us and a few other groups suggest that Raman spectroscopy can be exploited in instances where fast and accurate determination of the iodine value (associated with the degree of lipid unsaturation) is required. Here the current status of Raman spectroscopy applications on algae is reviewed, and particular attention is given to the efforts of identifying and selecting oil-rich algal strains for the potential mass production of commercial biofuels and for utilization in the food industry.

  19. Raman Spectroscopy Studies of Normal and Burned Biological Tissue (United States)

    Zarnani, Faranak; Maass, David; Idris, Ahamed; Glosser, Robert


    Burn injuries are a significant medical problem, and need to be treated quickly and precisely. Burned skin needs to be removed early, within hours (less than 24 hrs) of injury, when the margins of the burn are still hard to define. Studies show that treating and excising burn wounds soon after the injury prevents the wound from becoming deeper, reduces the release of proinflammatory mediators, and reduces or prevents the systemic inflammatory reaction syndrome. Also, removing burned skin prepares the affected region for skin grafting. Raman spectroscopy could be used as an objective diagnostic method that will assist burn surgeons in removing burned skin precisely. As a first step in developing a diagnostic tool, we present Raman spectroscopy information from normal and burned ex vivo rat skin, and a comparison of our findings. Raman spectroscopy is explored for its specificity and sensitivity.

  20. Deep UV Resonance Raman Spectroscopy for Characterizing Amyloid Aggregation. (United States)

    Handen, Joseph D; Lednev, Igor K


    Deep UV resonance Raman spectroscopy is a powerful technique for probing the structure and formation mechanism of protein fibrils, which are traditionally difficult to study with other techniques owing to their low solubility and noncrystalline arrangement. Utilizing a tunable deep UV Raman system allows for selective enhancement of different chromophores in protein fibrils, which provides detailed information on different aspects of the fibrils' structure and formation. Additional information can be extracted with the use of advanced data treatment such as chemometrics and 2D correlation spectroscopy. In this chapter we give an overview of several techniques for utilizing deep UV resonance Raman spectroscopy to study the structure and mechanism of formation of protein fibrils. Clever use of hydrogen-deuterium exchange can elucidate the structure of the fibril core. Selective enhancement of aromatic amino acid side chains provides information about the local environment and protein tertiary structure. The mechanism of protein fibril formation can be investigated with kinetic experiments and advanced chemometrics.

  1. Implementation of Deep Ultraviolet Raman Spectroscopy


    Liu, Chuan; Berg, Rolf W.


    Denne afhandling, "Implementation of Deep Ultraviolet Raman spectroscopy”, består i hovedsagen af to dele. Deep Ultraviolet – også kaldt DUV – står for bølgelængdeområdet 200 til 300 nm. Første del, kapitlerne 1 til 4, handler om den instrumentelle teknologi i DUV Raman-systemet. Anden del, kapitlerne 5 og 6 fokuserer på nogle få anvendelser af DUV Ramanspektroskopien. Kapitel 1 giver en kort introduktion til Ramanspektroskopi i almindelighed og DUVs relation hertil. DUV Ramanspektrometrien h...

  2. Surface-enhanced Raman spectroscopy of urine by an ingenious near-infrared Raman spectrometer (United States)

    Feng, Shangyuan; Chen, Weiwei; Li, Yongzeng; Chen, Guannan; Huang, Zufang; Liao, Xiaohua; Xie, Zhiming; Chen, Rong


    This paper demonstrates the potential of an elaborately devised near-infrared Raman system in analysis of urine. The broad band in the long-wavelength region of the electronic absorption spectra of the sol with added adsorbent at certain concentrations has been explained in terms of the aggregation of the colloidal silver particles. We have reported the surface-enhanced Raman (SERS) spectra of urine, and studied the silver solution enhanced effects on the urine Raman scattering. The Raman bands of human's urine was assigned to certain molecule vibrations. We have found that different donators have dissimilar SERS of urine in different physiological condition. Comparatively few studies have explored the ability of Raman spectroscopy for the analysis of urine acid. In the present report, we investigated the ability of surface enhanced Raman spectroscopy to measure uric acid in the human urine. The results suggested that the present Raman system holds considerable promise for practical use. Practical applications such as the quantitative medical examination of urine metabolites may also be feasible in the near future.

  3. Infrared and Raman Spectroscopy Principles and Spectral Interpretation

    CERN Document Server

    Larkin, Peter


    Infrared and Raman Spectroscopy: Principles and Spectral Interpretation explains the background, core principles and tests the readers understanding of the important techniques of Infrared and Raman Spectroscopy. These techniques are used by chemists, environmental scientists, forensic scientists etc to identify unknown chemicals. In the case of an organic chemist these tools are part of an armory of techniques that enable them to conclusively prove what compound they have made, which is essential for those being used in medical applications. The book reviews basic principles, instrumentation

  4. Resonance Raman Spectroscopy of Free Radicals Produced by Ionizing Radiation

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter


    Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p-nitrobenzylchloride and......Applications of time-resolved resonance Raman spectroscopy to the study of short-lived free radicals produced by ionizing radiation are briefly reviewed. Potential advantages and limitations of this technique are discussed in the light of given examples. The reduction of p...

  5. Condition Assessment of Kevlar Composite Materials Using Raman Spectroscopy (United States)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor


    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.

  6. Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy (United States)

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


    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.

  7. Gradient temperature Raman spectroscopy identifies flexible sites in proline and alanine peptides (United States)

    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...

  8. Raman spectroscopy as a tool to understand Kerogen production potential (United States)

    Khatibi, S.; Ostadhassan, M.; Mohammed, R. A.; Alexeyev, A.


    A lot attention has given to unconventional reservoirs specifically oil shale in North America during the last decades. Understanding Kerogen properties in terms of maturity and production potential are crucial for unconventional reservoir. Since, the amount of hydrocarbon generation is a function of kerogen type and content in the formation, and the magnitude and duration in which heat and pressure were applied. This study presents a non-destructive and fast method to determine Kerogen properties in terms of Rock-Eval parameters by means of Raman Spectroscopy. Samples were gathered from upper and lower Bakken formation, with different maturities at different depth. Raman spectroscopy as a powerful nondestructive analytical tool for molecular reconstruction was employed to find Raman spectra of different samples. In the next step, Rock-Eval was performed for each sample and different measurements were made. Then in an original approach, correlation between Rock-Eval parameters with Raman Spectroscopy results was established to fully understand how kerogen productivity potentials can be reflected on the Raman response. Results showed, maturity related parameters (RO, Tmax), S1 (already generated oil in the rock), S2 (potential hydrocarbon) and OSI (oil saturation index as indication of potential oil flow zones) can be correlated to band separation, D band intensity, G band intensity and G/D intensity, respectively. Proposed method provide a fast nondestructive method to evaluate Kerogen quality even at field without any special sample preparation.

  9. Strain characterization of FinFETs using Raman spectroscopy

    International Nuclear Information System (INIS)

    Kaleli, B.; Hemert, T. van; Hueting, R.J.E.; Wolters, R.A.M.


    Metal induced strain in the channel region of silicon (Si) fin-field effect transistor (FinFET) devices has been characterized using Raman spectroscopy. The strain originates from the difference in thermal expansion coefficient of Si and titanium-nitride. The Raman map of the device region is used to determine strain in the channel after preparing the device with the focused ion beam milling. Using the Raman peak shift relative to that of relaxed Si, compressive strain values up to – 0.88% have been obtained for a 5 nm wide silicon fin. The strain is found to increase with reducing fin width though it scales less than previously reported results from holographic interferometry. In addition, finite-element method (FEM) simulations have been utilized to analyze the amount of strain generated after thermal processing. It is shown that obtained FEM simulated strain values are in good agreement with the calculated strain values obtained from Raman spectroscopy. - Highlights: ► Strain is characterized in nanoscale devices with Raman spectroscopy. ► There is a fin width dependence of the originated strain. ► Strain levels obtained from this technique is in correlation with device simulations

  10. Raman spectroscopy and oral exfoliative cytology (United States)

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


    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.

  11. Raman spectroscopy for detection of stretched DNAs on superhydrophobic surfaces

    KAUST Repository

    Marini, Monica


    A novel approach for the study of low concentrated DNAs (60 pM) using microRaman spectroscopy is reported. A superhydrophobic substrate with array of microPillars is fabricated over which the sample was drop casted. The substrate concentrates the molecules in a very small area with higher molecular density, enabling to carry out the microRaman measurements. Two different DNAs (single strand and double strand) were used to investigate through Raman technique. A spectral Raman difference was found to distinguish the ssDNA and dsDNAs. The approach can be of interest for a wide variety of applications ranging from biological materials interactions characterization to the biomedical field. © 2014 Elsevier B.V. All rights reserved.

  12. Quantitative monitoring of yeast fermentation using Raman spectroscopy

    DEFF Research Database (Denmark)

    Iversen, Jens A.; Berg, Rolf W.; Ahring, Birgitte K.


    of a Saccharomyces cerevisiae fermentation process using a Raman spectroscopy instrument equipped with a robust sapphire ball probe.A method was developed to correct the Raman signal for the attenuation caused by light scattering cell particulate, hence enabling quantification of reaction components and possibly...... measurement of yeast cell concentrations. Extinction of Raman intensities to more than 50 % during fermentation was normalized with approximated extinction expressions using Raman signal of water around 1,627 cm−1 as internal standard to correct for the effect of scattering. Complicated standard multi...... was followed by linear regression. In situ quantification measurements of the fermentation resulted in root mean square errors of prediction (RMSEP) of 2.357, 1.611, and 0.633 g/L for glucose, ethanol, and yeast concentrations, respectively....

  13. Polarized Raman spectroscopy of chemically vapour deposited diamond films

    International Nuclear Information System (INIS)

    Prawer, S.; Nugent, K.W.; Weiser, P.S.


    Polarized micro-Raman spectra of chemically vapour deposited diamond films are presented. It is shown that important parameters often extracted from the Raman spectra such as the ratio of the diamond to non-diamond component of the films and the estimation of the level of residual stress depend on the orientation of the diamond crystallites with respect to the polarization of the incident laser beam. The dependence originates from the fact that the Raman scattering from the non-diamond components in the films is almost completely depolarized whilst the scattering from the diamond components is strongly polarized. The results demonstrate the importance of taking polarization into account when attempting to use Raman spectroscopy in even a semi-quantitative fashion for the assessment of the purity, perfection and stress in CVD diamond films. 8 refs., 1 tab. 2 figs

  14. Cone penetrometer fiber optic raman spectroscopy probe assembly (United States)

    Kyle, Kevin R.; Brown, Steven B.


    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.

  15. [Near-infrared Raman spectroscopy for diagnosis of gastric cancer]. (United States)

    Jin, Shaoqin; Mao, Hua


    To establish a method for early diagnosis of gastric cancer using near-infrared Raman spectroscopy. A rapid near-infrared Raman system was used to examine the tissue specimens of pathologically confirmed gastric cancer (33 cases), gastric precancerous lesions (27 cases), and normal gastric mucosa (45 cases). All the specimens were obtained from 105 patients undergoing gastrectomy or endoscopic biopsy of suspected gastric lesions. High-quality Raman spectra ranging from 700 to 1800 cm(-1) were acquired from the gastric tissues within 5 s. The distribution pattern of Raman spectra in gastric cancer differed significantly from those of gastric precancerous lesions and normal gastric mucosa, particularly in the spectral ranges of 853 cm(-1), 936 cm(-1), 1003 cm(-1), 1032 cm(-1), 1174 cm(-1), 1208 cm(-1), 1323 cm(-1), 1335 cm(-1), 1450 cm(-1), and 1655 cm(-1), which contained signals related to proteins, nucleic acids and lipids. The diagnostic decision algorithm based on the Raman peak intensity ratios of I1003/ I1337, I1003/I1445, I1003/I1655, and I1156/I1655 yielded remarkable differences in gastric cancer from gastric precancerous lesions and normal gastric mucosa, and the ratios were significantly higher in normal gastric tissues (Pinfrared Raman spectroscopy using PCA-LDA algorithms associated with leave- one-out and cross-validation method showed diagnostic sensitivities of 81.5%, 85.3%, and 100%, and specificities of 86.4%, 100%, and 97.4% for normal gastric mucosa, precancerous lesions and gastric cancer, respectively. near-infrared Raman spectroscopy in conjunction with intensity ratio algorithms shows the potential for noninvasive diagnosis and detection of gastric malignancy at the molecular level.

  16. Raman-spectroscopy-based biosensing for applications in ophthalmology (United States)

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


    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.

  17. Optical trapping and Raman spectroscopy of single nanostructures using standing-wave Raman tweezers (United States)

    Wu, Mu-ying; He, Lin; Chen, Gui-hua; Yang, Guang; Li, Yong-qing


    Optical tweezers integrated with Raman spectroscopy allows analyzing a single trapped micro-particle, but is generally less effective for individual nano-sized objects in the 10-100 nm range. The main challenge is the weak gradient force on nanoparticles that is insufficient to overcome the destabilizing effect of scattering force and Brownian motion. Here, we present standing-wave Raman tweezers for stable trapping and sensitive characterization of single isolated nanostructures with a low laser power by combining a standing-wave optical trap (SWOT) with confocal Raman spectroscopy. This scheme has stronger intensity gradients and balanced scattering forces, and thus is more stable and sensitive in measuring nanoparticles in liquid with 4-8 fold increase in the Raman signals. It can be used to analyze many nanoparticles that cannot be measured with single-beam Raman tweezers, including individual single-walled carbon nanotubes (SWCNT), graphene flakes, biological particles, polystyrene beads (100 nm), SERS-active metal nanoparticles, and high-refractive semiconductor nanoparticles with a low laser power of a few milliwatts. This would enable sorting and characterization of specific SWCNTs and other nanoparticles based on their increased Raman fingerprints.

  18. Raman spectroscopy in quality control of Chinese herbal medicine

    Directory of Open Access Journals (Sweden)

    Dan-Dan Chen


    Conclusion: An updated systematic review of the published literature has been conducted to analyze the most important milestones and latest achievements in this topic. Raman spectroscopy is playing an increasingly important role in the quality control of CHM and effectively promotes the modernization of CHM.

  19. Integrated optical modules for miniature raman spectroscopy devices

    NARCIS (Netherlands)

    Çivitci, F.


    Raman spectroscopy is a powerful materials analysis technique used for identification of molecules residing near the surface of a sample. It has been successfully used for a broad range of application areas such as material science, biology, medicine and pharmacology owing to its numerous

  20. Determination of cellulose I crystallinity by FT-Raman spectroscopy (United States)

    Umesh P. Agarwal; Richard S. Reiner; Sally A. Ralph


    Two new methods based on FT-Raman spectroscopy, one simple, based on band intensity ratio, and the other, using a partial least-squares (PLS) regression model, are proposed to determine cellulose I crystallinity. In the simple method, crystallinity in semicrystalline cellulose I samples was determined based on univariate regression that was first developed using the...

  1. Analysis of scorpion venom composition by Raman Spectroscopy (United States)

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


    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.

  2. Stress Analysis of SiC MEMS Using Raman Spectroscopy (United States)

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


    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.

  3. Strong overtones and combination bands in ultraviolet resonance Raman spectroscopy

    NARCIS (Netherlands)

    Efremov, E.V.; Ariese, F.; Mank, A.J.G.; Gooijer, C.


    Ultraviolet resonance Raman spectroscopy is carried out using a continuous wave frequency-doubled argon ion laser operated at 229, 244, and 257 nm in order to characterize the overtones and combination bands for several classes of organic compounds in liquid solutions. Contrary to what is generally

  4. Diffusion measurements in binary liquid mixtures by Raman spectroscopy

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Hansen, Susanne Brunsgaard; Shapiro, Alexander


    It is shown that Raman spectroscopy allows determination of the molar fractions in mixtures subjected to molecular diffusion. Spectra of three binary systems, benzene/n-hexane, benzene/cyclohexane, and benzene/ acetone, were obtained during vertical (exchange) diffusion at several different heights...

  5. Fabricating a UV-Vis and Raman Spectroscopy Immunoassay Platform. (United States)

    Hanson, Cynthia; Israelsen, Nathan D; Sieverts, Michael; Vargis, Elizabeth


    Immunoassays are used to detect proteins based on the presence of associated antibodies. Because of their extensive use in research and clinical settings, a large infrastructure of immunoassay instruments and materials can be found. For example, 96- and 384-well polystyrene plates are available commercially and have a standard design to accommodate ultraviolet-visible (UV-Vis) spectroscopy machines from various manufacturers. In addition, a wide variety of immunoglobulins, detection tags, and blocking agents for customized immunoassay designs such as enzyme-linked immunosorbent assays (ELISA) are available. Despite the existing infrastructure, standard ELISA kits do not meet all research needs, requiring individualized immunoassay development, which can be expensive and time-consuming. For example, ELISA kits have low multiplexing (detection of more than one analyte at a time) capabilities as they usually depend on fluorescence or colorimetric methods for detection. Colorimetric and fluorescent-based analyses have limited multiplexing capabilities due to broad spectral peaks. In contrast, Raman spectroscopy-based methods have a much greater capability for multiplexing due to narrow emission peaks. Another advantage of Raman spectroscopy is that Raman reporters experience significantly less photobleaching than fluorescent tags 1 . Despite the advantages that Raman reporters have over fluorescent and colorimetric tags, protocols to fabricate Raman-based immunoassays are limited. The purpose of this paper is to provide a protocol to prepare functionalized probes to use in conjunction with polystyrene plates for direct detection of analytes by UV-Vis analysis and Raman spectroscopy. This protocol will allow researchers to take a do-it-yourself approach for future multi-analyte detection while capitalizing on pre-established infrastructure.

  6. Stokes and anti-stokes stimulated Mie scattering on nanoparticle suspensions of latex (United States)

    Burkhanov, I. S.; Krivokhizha, S. V.; Chaikov, L. L.


    Stokes and anti-Stokes shifts of stimulated concentration light scattering (SCLS, stimulated Mie scattering) in suspensions of various-sized latex nanoparticles in water were measured by the light guide scheme, under conditions of backscattering in the presence of convection.

  7. Analysis of tooth tissues using Raman spectroscopy

    International Nuclear Information System (INIS)

    Timchenko, E.V.; Timchenko, P.E.; Kulabukhova, A.Yu.; Volova, L.T.; Rosenbaum, A.Yu.


    The results of experimental studies of healthy tooth tissue and tooth tissues during caries disease are presented. Features of Raman spectrum of tooth tissues during caries disease are obtained: the main changes are detected at wavenumbers 956 cm -1 .1069 cm -1 . corresponding to phosphates. and 1241 cm -1 . 1660 cm -1 . corresponding to collagen III and collagen I. respectively. Were introduced criteria allowing to detect caries and to identify weakening of tooth tissues. preceding the caries. The reliability of research results is confirmed by scanning electron microscopy. (paper)

  8. Raman Spectroscopy and in Situ Raman Spectroelectrochemistry of Isotopically Engineered Graphene Systems

    Czech Academy of Sciences Publication Activity Database

    Frank, Otakar; Dresselhaus, M. S.; Kalbáč, Martin


    Roč. 48, č. 1 (2015), s. 111-118 ISSN 0001-4842 R&D Projects: GA MŠk LH13022; GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : Raman spectroscopy * spectroelectrochemistry * graphene Subject RIV: CG - Electrochemistry Impact factor: 22.003, year: 2015

  9. Enhanced Control of Transient Raman Scattering Using Buffered Hydrogen in Hollow-Core Photonic Crystal Fibers (United States)

    Hosseini, P.; Novoa, D.; Abdolvand, A.; Russell, P. St. J.


    Many reports on stimulated Raman scattering in mixtures of Raman-active and noble gases indicate that the addition of a dispersive buffer gas increases the phase mismatch to higher-order Stokes and anti-Stokes sidebands, resulting in a preferential conversion to the first few Stokes lines, accompanied by a significant reduction in the Raman gain due to collisions with gas molecules. Here we report that, provided the dispersion can be precisely controlled, the effective Raman gain in a gas-filled hollow-core photonic crystal fiber can actually be significantly enhanced when a buffer gas is added. This counterintuitive behavior occurs when the nonlinear coupling between the interacting fields is strong and can result in a performance similar to that of a pure Raman-active gas, but at a much lower total gas pressure, allowing competing effects such as Raman backscattering to be suppressed. We report high modal purity in all the emitted sidebands, along with anti-Stokes conversion efficiencies as high as 5% in the visible and 2% in the ultraviolet. This new class of gas-based waveguide device, which allows the nonlinear optical response to be beneficially pressure-tuned by the addition of buffer gases, may find important applications in laser science and spectroscopy.

  10. Raman spectroscopy of Bacillus thuringiensis physiology and inactivation (United States)

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


    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.

  11. Bladder cancer diagnosis during cystoscopy using Raman spectroscopy (United States)

    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.


    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.

  12. Raman spectroscopy for intracellular monitoring of carotenoid in Blakeslea trispora. (United States)

    Papaioannou, Emmanouil H; Liakopoulou-Kyriakides, Maria; Christofilos, Dimitrios; Arvanitidis, Ioannis; Kourouklis, Gerasimos


    In the present study, we explore the feasibility of Raman spectroscopy for intracellular monitoring of carotenoid in filamentous fungi Blakeslea trispora. Although carotenoid production from this fungus has been extensively studied through various chromatographic methods and ultraviolet-visible spectroscopy, no intracellular monitoring has been demonstrated until now. The intensity of the Raman spectrum, and more conveniently that of the strongest nu(1) carotenoid band at approximately 1,519 cm(-1), exhibits a good linear correlation with the carotenoid content of the sample as determined by high-performance liquid chromatography (HPLC) and ultraviolet-visible (UV-Vis) spectroscopy. Our results suggest that Raman spectroscopy can serve as an alternative method for the study and quantification of carotenoid in batch-mated submerged cultivations of B. trispora and similar organisms. Although not as accurate as HPLC, it allows a rapid sampling and analysis, avoiding the prolonged and tedious classical isolation procedures required for carotenoid determination by HPLC and UV-Vis spectroscopy.

  13. Transcutaneous Raman spectroscopy of murine bone in vivo. (United States)

    Schulmerich, Matthew V; Cole, Jacqueline H; Kreider, Jaclynn M; Esmonde-White, Francis; Dooley, Kathryn A; Goldstein, Steven A; Morris, Michael D


    Raman spectroscopy can provide valuable information about bone tissue composition in studies of bone development, biomechanics, and health. In order to study the Raman spectra of bone in vivo, instrumentation that enhances the recovery of subsurface spectra must be developed and validated. Five fiber-optic probe configurations were considered for transcutaneous bone Raman spectroscopy of small animals. Measurements were obtained from the tibia of sacrificed mice, and the bone Raman signal was recovered for each probe configuration. The configuration with the optimal combination of bone signal intensity, signal variance, and power distribution was then evaluated under in vivo conditions. Multiple in vivo transcutaneous measurements were obtained from the left tibia of 32 anesthetized mice. After collecting the transcutaneous Raman signal, exposed bone measurements were collected and used as a validation reference. Multivariate analysis was used to recover bone spectra from transcutaneous measurements. To assess the validity of the transcutaneous bone measurements cross-correlations were calculated between standardized spectra from the recovered bone signal and the exposed bone measurements. Additionally, the carbonate-to-phosphate height ratios of the recovered bone signals were compared to the reference exposed bone measurements. The mean cross-correlation coefficient between the recovered and exposed measurements was 0.96, and the carbonate-to-phosphate ratios did not differ significantly between the two sets of spectra (p > 0.05). During these first systematic in vivo Raman measurements, we discovered that probe alignment and animal coat color influenced the results and thus should be considered in future probe and study designs. Nevertheless, our noninvasive Raman spectroscopic probe accurately assessed bone tissue composition through the skin in live mice.

  14. Micro-Raman spectroscopy of collotelinite, fusinite and macrinite

    Energy Technology Data Exchange (ETDEWEB)

    Guedes, A.; Valentim, B.; Rodrigues, S.; Noronha, F. [Centro de Geologia e Departamento de Geociencias, Ambiente e Ordenamento do Territorio da Faculdade de Ciencias, Universidade do Porto, 4169-007-Porto (Portugal); Prieto, A.C. [Departamento de Fisica de la Materia Condensada, Cristalografia y Mineralogia Facultad de Ciencias, Universidad de Valladolid, 47011-Valladolid (Spain)


    The Raman spectra and the Raman parameters have been correlated with changes in the structure of carbon materials, and most of the studies have revealed different development of the Raman spectrum. In the present study micro-Raman spectroscopy was conducted on coal bulk samples and on individual coal macerals (collotelinite, fusinite, and macrinite) from a set of Penn State Coal Bank coals of increasing rank to study the variation of their spectral parameters with rank, and considering coal heterogeneity. The spectral parameters that better correlate with the increasing coal rank, for the coals studied are the full width at half maximum of graphitic band (G: at {proportional_to} 1580 cm{sup -} {sup 1}), the position of disordered band (D: at {proportional_to} 1350 cm{sup -} {sup 1}), and the integrated intensity ratio of the D band to G band (ID/IG). With increasing coal rank a narrower G band, a shift of D band to lower wavenumber, and an increase of integrated intensity ratio ID/IG are observed. For each coal, the Raman parameters obtained on fusinites and macrinites are similar and differ from those obtained on coal bulk samples and collotelinites. The variation of the Raman parameters with rank is very well reflected on the analyses of collotelinites. (author)

  15. Raman spectroscopy on simple molecular systems at very high density

    International Nuclear Information System (INIS)

    Schiferl, D.; LeSar, R.S.; Moore, D.S.


    We present an overview of how Raman spectroscopy is done on simple molecular substances at high pressures. Raman spectroscopy is one of the most powerful tools for studying these substances. It is often the quickest means to explore changes in crystal and molecular structures, changes in bond strength, and the formation of new chemical species. Raman measurements have been made at pressures up to 200 GPa (2 Mbar). Even more astonishing is the range of temperatures (4-5200/degree/K) achieved in various static and dynamic (shock-wave) pressure experiments. One point we particularly wish to emphasize is the need for a good theoretical understanding to properly interpret and use experimental results. This is particularly true at ultra-high pressures, where strong crystal field effects can be misinterpreted as incipient insulator-metal transitions. We have tried to point out apparatus, techniques, and results that we feel are particularly noteworthy. We have also included some of the /open quotes/oral tradition/close quotes/ of high pressure Raman spectroscopy -- useful little things that rarely or never appear in print. Because this field is rapidly expanding, we discuss a number of exciting new techniques that have been informally communicated to us, especially those that seem to open new possibilities. 58 refs., 18 figs

  16. Temperature-dependent Photodegradation in UV-resonance Raman Spectroscopy. (United States)

    Yoshino, Hikaru; Saito, Yuika; Kumamoto, Yasuaki; Taguchi, Atushi; Verma, Prabhat; Kawata, Satoshi


    Temperature-dependent photodegradation during UV-resonance Raman spectroscopy was investigated. Photodegradation was quantitatively probed by monitoring the temporal evolution of UV-resonance Raman spectra obtained from bacteriochlorophyll (BChl) showing, resonance effect at a 355-nm excitation wavelength. At 80 K, the molecular photodecomposition rate was 5-times lower than that at room temperature. The decomposition rates of BChl were analyzed by the Arrhenius formula, indicating that the mechanism of photodegradation includes a thermal process having an activation energy of 1.4 kJ/mol.

  17. Raman spectroscopy of tellurate-tungstate glasses

    International Nuclear Information System (INIS)

    Gugov, I.B.; Brovchenko, I.M.; Kabanov, V.O.; Yanush, O.V.


    The Raman spectra of xTeO 2 - (1-x)WO 3 glasses, where 0.75 4 , WO 4 and WO 6 structural groups observed. This is in accordance with the absence of some chemical compounds between TeO 2 and WO 3 in the phase diagram of the system. The presence of WO 4 tetrahedra in the glasses, not observed in the different WO 3 crystalline modifications and the crystallized glasses, was defined as a feature of WO 3 g lassy state . It was suggested that the WO 4 tetrahedron does not replace equivalently the TeO 4 polyhedron in the glass structure, as it was reported previously, because of the different valency state of both cations. (author)

  18. Optical Coherence Tomography and Raman Spectroscopy of the retina

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  19. Resonance Raman spectroscopy in one-dimensional carbon materials

    Directory of Open Access Journals (Sweden)

    Dresselhaus Mildred S.


    Full Text Available Brazil has played an important role in the development and use of resonance Raman spectroscopy as a powerful characterization tool for materials science. Here we present a short history of Raman scattering research in Brazil, highlighting the important contributions to the field coming from Brazilian researchers in the past. Next we discuss recent and important contributions where Brazil has become a worldwide leader, that is on the physics of quasi-one dimensional carbon nanotubes. We conclude this article by presenting results from a very recent resonance Raman study of exciting new materials, that are strictly one-dimensional carbon chains formed by the heat treatment of very pure double-wall carbon nanotube samples.

  20. Gate dependent Raman spectroscopy of graphene on hexagonal boron nitride. (United States)

    Chattrakun, Kanokporn; Huang, Shengqiang; Watanabe, K; Taniguchi, T; Sandhu, A; LeRoy, B J


    Raman spectroscopy, a fast and nondestructive imaging method, can be used to monitor the doping level in graphene devices. We fabricated chemical vapor deposition (CVD) grown graphene on atomically flat hexagonal boron nitride (hBN) flakes and SiO2 substrates. We compared their Raman response as a function of charge carrier density using an ion gel as a top gate. The G peak position, the 2D peak position, the 2D peak width and the ratio of the 2D peak area to the G peak area show a dependence on carrier density that differs for hBN compared to SiO2. Histograms of two-dimensional mapping are used to compare the fluctuations in the Raman peak properties between the two substrates. The hBN substrate has been found to produce fewer fluctuations at the same charge density owing to its atomically flat surface and reduced charged impurities.

  1. Screening and classification of ordinary chondrites by Raman spectroscopy (United States)

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


    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.

  2. Fourier transform Raman spectroscopy of polyacrylamide gels for radiation dosimetry

    International Nuclear Information System (INIS)

    Baldock, C.; Murry, P.; Pope, J.; Rintoul, L.; George, G.


    Polyacrylamide (PAG) gels are used in magnetic resonance imaging radiation dosimetry. The PAG dosimeter is based on the radiation-induced co-polymerisation and cross-linking of acrylic monomers infused in a gel matrix. PAG was manufactured with a composition of 5% gelatine, 3% acrylamide and 3% N,N'methylene-bis-acrylamide by mass, with distilled water as the remaining constituent [Baldock, 1998]. FT-Raman spectroscopy studies were undertaken to investigate cross-linking changes during the co-polymerisation of PAG in the spectral range of 200 - 3500 cm -1 . Vibrational bands of 1285 cm -1 and 1256 cm -1 were assigned to the acrylamide and bis-acrylamide single CH 2 δ CH2 binding modes. These bands were found to decrease in amplitude with increasing absorbed radiation dose, as a result of co-polymerisation. Principal Component Regression was performed on FT-Raman spectra of PAG samples irradiated to 50 Gy and two components were found to be sufficient to account for 98.7% of variance in the data. Cross validation was used to establish the absorbed radiation dose of an unknown PAG sample from the FT-Raman spectra. The calculated correlation coefficient between measured and predictive samples was 0.997 with a standard error of estimate of 0.976 and a standard error of prediction of 1.140. These results demonstrate the potential of FT-Raman spectroscopy for ionising radiation dosimetry using polyacrylamide gels

  3. Determination of human coronary artery composition by Raman spectroscopy. (United States)

    Brennan, J F; Römer, T J; Lees, R S; Tercyak, A M; Kramer, J R; Feld, M S


    We present a method for in situ chemical analysis of human coronary artery using near-infrared Raman spectroscopy. It is rapid and accurate and does not require tissue removal; small volumes, approximately 1 mm3, can be sampled. This methodology is likely to be useful as a tool for intravascular diagnosis of artery disease. Human coronary artery segments were obtained from nine explanted recipient hearts within 1 hour of heart transplantation. Minces from one or more segments were obtained through grinding in a mortar and pestle containing liquid nitrogen. Artery segments and minces were excited with 830 nm near-infrared light, and Raman spectra were collected with a specially designed spectrometer. A model was developed to analyze the spectra and quantify the amounts of cholesterol, cholesterol esters, triglycerides and phospholipids, and calcium salts present. The model provided excellent fits to spectra from the artery segments, indicating its applicability to intact tissue. In addition, the minces were assayed chemically for lipid and calcium salt content, and the results were compared. The relative weights obtained using the Raman technique agreed with those of the standard assays within a few percentage points. The chemical composition of coronary artery can be quantified accurately with Raman spectroscopy. This opens the possibility of using histochemical analysis to predict acute events such as plaque rupture, to follow the progression of disease, and to select appropriate therapeutic interventions.

  4. Cell Imaging by Spontaneous and Amplified Raman Spectroscopies

    Directory of Open Access Journals (Sweden)

    Giulia Rusciano


    Full Text Available Raman spectroscopy (RS is a powerful, noninvasive optical technique able to detect vibrational modes of chemical bonds. The high chemical specificity due to its fingerprinting character and the minimal requests for sample preparation have rendered it nowadays very popular in the analysis of biosystems for diagnostic purposes. In this paper, we first discuss the main advantages of spontaneous RS by describing the study of a single protozoan (Acanthamoeba, which plays an important role in a severe ophthalmological disease (Acanthamoeba keratitis. Later on, we point out that the weak signals that originated from Raman scattering do not allow probing optically thin samples, such as cellular membrane. Experimental approaches able to overcome this drawback are based on the use of metallic nanostructures, which lead to a huge amplification of the Raman yields thanks to the excitation of localized surface plasmon resonances. Surface-enhanced Raman scattering (SERS and tip-enhanced Raman scattering (TERS are examples of such innovative techniques, in which metallic nanostructures are assembled on a flat surface or on the tip of a scanning probe microscope, respectively. Herein, we provide a couple of examples (red blood cells and bacterial spores aimed at studying cell membranes with these techniques.

  5. NIR Raman spectroscopy in medicine and biology: results and aspects (United States)

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


    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.

  6. Determination of butter adulteration with margarine using Raman spectroscopy. (United States)

    Uysal, Reyhan Selin; Boyaci, Ismail Hakki; Genis, Hüseyin Efe; Tamer, Ugur


    In this study, adulteration of butter with margarine was analysed using Raman spectroscopy combined with chemometric methods (principal component analysis (PCA), principal component regression (PCR), partial least squares (PLS)) and artificial neural networks (ANNs). Different butter and margarine samples were mixed at various concentrations ranging from 0% to 100% w/w. PCA analysis was applied for the classification of butters, margarines and mixtures. PCR, PLS and ANN were used for the detection of adulteration ratios of butter. Models were created using a calibration data set and developed models were evaluated using a validation data set. The coefficient of determination (R(2)) values between actual and predicted values obtained for PCR, PLS and ANN for the validation data set were 0.968, 0.987 and 0.978, respectively. In conclusion, a combination of Raman spectroscopy with chemometrics and ANN methods can be applied for testing butter adulteration. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Raman spectroscopy as a tool for ecology and evolution. (United States)

    Germond, Arno; Kumar, Vipin; Ichimura, Taro; Moreau, Jerome; Furusawa, Chikara; Fujita, Hideaki; Watanabe, Tomonobu M


    Scientists are always on the lookout for new modalities of information which could reveal new biological features that are useful for deciphering the complexity of biological systems. Here, we introduce Raman spectroscopy as a prime candidate for ecology and evolution. To encourage the integration of this microscopy technique in the field of ecology and evolution, it is crucial to discuss first how Raman spectroscopy fits within the conceptual, technical and pragmatic considerations of ecology and evolution. In this paper, we show that the spectral information holds reliable indicators of intra- and interspecies variations, which can be related to the environment, selective pressures and fitness. Moreover, we show how the technical and pragmatic aspects of this modality (non-destructive, non-labelling, speed, relative low cost, etc.) enable it to be combined with more conventional methodologies. With this paper, we hope to open new avenues of research and extend the scope of available methodologies used in ecology and evolution. © 2017 The Authors.

  8. Comparison of Fresh and Aged TNT with Multiwavelength Raman Spectroscopy (United States)


    bulk TNT in the UV resulted in poor data quality. Because of this, we switched to visible illumination wavelengths between 420nm to 620nm. To...Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/6730--14-9572 Comparison of Fresh and Aged TNT with Multiwavelength Raman Spectroscopy ...RobeRt LunsfoRd Jacob GRun Laser Plasma Branch Plasma Physics Division PRatima KunaPaReddy Research Support Instruments Lanham, Maryland December 4

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

    Czech Academy of Sciences Publication Activity Database

    Mlynariková, K.; Samek, Ota; Bernatová, Silvie; Růžička, F.; Ježek, Jan; Hároniková, A.; Šiler, Martin; Zemánek, Pavel; Holá, V.


    Roč. 15, č. 11 (2015), s. 29635-29647 ISSN 1424-8220 R&D Projects: GA MŠk ED0017/01/01; GA ČR(CZ) GA15-20645S; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : Raman spectroscopy * bacteria * yeasts * culture media Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.033, year: 2015

  10. Probing strain in bent semiconductor nanowires with Raman spectroscopy. (United States)

    Chen, Jianing; Conache, Gabriela; Pistol, Mats-Erik; Gray, Struan M; Borgström, Magnus T; Xu, Hongxing; Xu, H Q; Samuelson, Lars; Håkanson, Ulf


    We present a noninvasive optical method to determine the local strain in individual semiconductor nanowires. InP nanowires were intentionally bent with an atomic force microscope and variations in the optical phonon frequency along the wires were mapped using Raman spectroscopy. Sections of the nanowires with a high curvature showed significantly broadened phonon lines. These observations together with deformation potential theory show that compressive and tensile strain inside the nanowires is the physical origin of the observed phonon energy variations.

  11. Evaluation of Raman spectroscopy to detect fullerenes in geological materials

    Czech Academy of Sciences Publication Activity Database

    Jehlička, J.; Frank, O.; Pokorný, Jan; Rouzaud, J. N.


    Roč. 61, - (2005), s. 2364-2367 ISSN 1386-1425 R&D Projects: GA ČR(CZ) GA205/03/1468 Grant - others:MŠk(XX) 2003-046-2 Institutional research plan: CEZ:AV0Z10100520 Keywords : Raman spectroscopy * fullerenes * rocks * minerals Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.290, year: 2005

  12. Medical applications of atomic force microscopy and Raman spectroscopy. (United States)

    Choi, Samjin; Jung, Gyeong Bok; Kim, Kyung Sook; Lee, Gi-Ja; Park, Hun-Kuk


    This paper reviews the recent research and application of atomic force microscopy (AFM) and Raman spectroscopy techniques, which are considered the multi-functional and powerful toolkits for probing the nanostructural, biomechanical and physicochemical properties of biomedical samples in medical science. We introduce briefly the basic principles of AFM and Raman spectroscopy, followed by diagnostic assessments of some selected diseases in biomedical applications using them, including mitochondria isolated from normal and ischemic hearts, hair fibers, individual cells, and human cortical bone. Finally, AFM and Raman spectroscopy applications to investigate the effects of pharmacotherapy, surgery, and medical device therapy in various medicines from cells to soft and hard tissues are discussed, including pharmacotherapy--paclitaxel on Ishikawa and HeLa cells, telmisartan on angiotensin II, mitomycin C on strabismus surgery and eye whitening surgery, and fluoride on primary teeth--and medical device therapy--collagen cross-linking treatment for the management of progressive keratoconus, radiofrequency treatment for skin rejuvenation, physical extracorporeal shockwave therapy for healing of Achilles tendinitis, orthodontic treatment, and toothbrushing time to minimize the loss of teeth after exposure to acidic drinks.

  13. Raman spectroscopy characterization of colored pigments in archaeological materials

    DEFF Research Database (Denmark)

    Berg, Rolf W.

    Archaeological artifacts and artworks with colors are being increasingly analyzed in these years. The pigment materials used for their creation are much studied after the development of modern non-destructive micro sampling analytical techniques. Art historians, museum conservators, and archaeolo......Archaeological artifacts and artworks with colors are being increasingly analyzed in these years. The pigment materials used for their creation are much studied after the development of modern non-destructive micro sampling analytical techniques. Art historians, museum conservators...... to the artifacts or artworks. In this connection the Raman spectroscopy technique must be considered a most elegant method for pigment and materials analysis of relevant museum and archaeological materials. This is done by correlating some bands in the studied pigments with those of well characterized references....... The number of research papers on the subject of Raman spectroscopy applied to pigments and art has been growing very fast during the last years. To get a comprehensive overview we refer to three recent theme numbers of Journal of Raman Spectroscopy1, 2, 3 and other dedicated texts such as e.g. Edwards et al...

  14. Infrared and NIR Raman spectroscopy in medical microbiology (United States)

    Naumann, Dieter


    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.

  15. Communication: atomic force detection of single-molecule nonlinear optical vibrational spectroscopy. (United States)

    Saurabh, Prasoon; Mukamel, Shaul


    Atomic Force Microscopy (AFM) allows for a highly sensitive detection of spectroscopic signals. This has been first demonstrated for NMR of a single molecule and recently extended to stimulated Raman in the optical regime. We theoretically investigate the use of optical forces to detect time and frequency domain nonlinear optical signals. We show that, with proper phase matching, the AFM-detected signals closely resemble coherent heterodyne-detected signals. Applications are made to AFM-detected and heterodyne-detected vibrational resonances in Coherent Anti-Stokes Raman Spectroscopy (χ((3))) and sum or difference frequency generation (χ((2))).

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

    Energy Technology Data Exchange (ETDEWEB)

    Stokes, D.L.


    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

  17. Interfacing capillary electrophoresis and surface-enhanced resonance Raman spectroscopy for the determination of dye compounds

    NARCIS (Netherlands)

    Arraez Roman, D.; Efremov, E.V.; Ariese, F.; Segura Carretero, A.; Gooijer, C.


    The at-line coupling of capillary electrophoresis (CE) and surface-enhanced resonance Raman spectroscopy (SERRS) was optimized for the separation and subsequent spectroscopic identification of charged analytes (dye compounds). Raman spectra were recorded following deposition of the electropherogram

  18. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    Energy Technology Data Exchange (ETDEWEB)

    Melendres, C.A.


    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.

  19. Detection of hazardous chemicals using field-portable Raman spectroscopy (United States)

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


    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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Yuan; Li, Yuandong; Li, Ying [Optics and Optoelectronics Lab, Ocean University of China, Qingdao 266100 (China); Wang, Yangfan; Wang, Shi; Bao, Zhenmin [Life Science College, Ocean University of China, Qingdao 266003 (China); Zheng, Ronger, E-mail: [Optics and Optoelectronics Lab, Ocean University of China, Qingdao 266100 (China)


    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. - Highlights: • A LIBS–Raman hybrid system was developed. • A seashell has been analyzed for the elementary and molecular distribution with a system. • The shell growth development was studied on the surface and in the depth.

  1. Cavity-Enhanced Raman Spectroscopy for Food Chain Management

    Directory of Open Access Journals (Sweden)

    Vincenz Sandfort


    Full Text Available Comprehensive food chain management requires the monitoring of many parameters including temperature, humidity, and multiple gases. The latter is highly challenging because no low-cost technology for the simultaneous chemical analysis of multiple gaseous components currently exists. This contribution proposes the use of cavity enhanced Raman spectroscopy to enable online monitoring of all relevant components using a single laser source. A laboratory scale setup is presented and characterized in detail. Power enhancement of the pump light is achieved in an optical resonator with a Finesse exceeding 2500. A simulation for the light scattering behavior shows the influence of polarization on the spatial distribution of the Raman scattered light. The setup is also used to measure three relevant showcase gases to demonstrate the feasibility of the approach, including carbon dioxide, oxygen and ethene.

  2. Discrimination of wine lactic acid bacteria by Raman spectroscopy. (United States)

    Rodriguez, Susan B; Thornton, Mark A; Thornton, Roy J


    Species of Lactobacillus, Pediococcus, Oenococcus, and Leuconostoc play an important role in winemaking, as either inoculants or contaminants. The metabolic products of these lactic acid bacteria have considerable effects on the flavor, aroma, and texture of a wine. However, analysis of a wine's microflora, especially the bacteria, is rarely done unless spoilage becomes evident, and identification at the species or strain level is uncommon as the methods required are technically difficult and expensive. In this work, we used Raman spectral fingerprints to discriminate 19 strains of Lactobacillus, Pediococcus, and Oenococcus. Species of Lactobacillus and Pediococcus and strains of O. oeni and P. damnosus were classified with high sensitivity: 86-90 and 84-85%, respectively. Our results demonstrate that a simple, inexpensive method utilizing Raman spectroscopy can be used to accurately identify lactic acid bacteria isolated from wine.

  3. Controlling protected designation of origin of wine by Raman spectroscopy. (United States)

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


    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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Surface-enhanced Raman spectroscopy bioanalytical, biomolecular and medical applications

    CERN Document Server

    Procházka, Marek


    This book gives an overview of recent developments in RS and SERS for sensing and biosensing considering also limitations, possibilities and prospects of this technique. Raman scattering (RS) is a widely used vibrational technique providing highly specific molecular spectral patterns. A severe limitation for the application of this spectroscopic technique lies in the low cross section of RS. Surface-enhanced Raman scattering (SERS) spectroscopy overcomes this problem by 6-11 orders of magnitude enhancement compared with the standard RS for molecules in the close vicinity of certain rough metal surfaces. Thus, SERS combines molecular fingerprint specificity with potential single-molecule sensitivity. Due to the recent development of new SERS-active substrates, labeling and derivatization chemistry as well as new instrumentations, SERS became a very promising tool for many varied applications, including bioanalytical studies and sensing. Both intrinsic and extrinsic SERS biosensing schemes have been employed to...

  5. Applications of Raman spectroscopy to the analysis of natural rubber (United States)

    Hendra, Patrick J.; Jackson, Kevin D. O.


    The technique of Raman spectroscopy has been available for over 60 years but the analysis of elastomers has been dogged by problems of fluorescence. The introduction of Fourier transform collection techniques and spectral accumulation, coupled with the advantages of using a near-IR laser as an excitation source, have removed many of the barriers to the application of this technique within a routine laboratory environment. This paper describes some of the areas related to the analysis of natural rubber which have been investigated using this technique. Of particular interest is the observation of main chain modifications during vulcanization and the ability to observe the conversion of insoluble to soluble sulphur under conditions appropriate to compounding and vulcanization. The influence of crystallization, both temperature and strain induced, on the FT-Raman spectrum of natural rubber is also demonstrated.

  6. Rapid Classification of Ordinary Chondrites Using Raman Spectroscopy (United States)

    Fries, M.; Welzenbach, L.


    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.

  7. Raman spectroscopy for DNA quantification in cell nucleus. (United States)

    Okotrub, K A; Surovtsev, N V; Semeshin, V F; Omelyanchuk, L V


    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. © 2014 International Society for Advancement of Cytometry.

  8. Raman Spectroscopy: an essential tool for future IODP expeditions (United States)

    Andò, Sergio; Garzanti, Eduardo; Kulhanek, Denise K.


    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

  9. Amino acid quantification in bulk soybeans by transmission Raman spectroscopy. (United States)

    Schulmerich, Matthew V; Gelber, Matthew K; Azam, Hossain M; Harrison, Sandra K; McKinney, John; Thompson, Dennis; Owen, Bridget; Kull, Linda S; Bhargava, Rohit


    Soybeans are a commodity crop of significant economic and nutritional interest. As an important source of protein, buyers of soybeans are interested in not only the total protein content but also in the specific amino acids that comprise the total protein content. Raman spectroscopy has the chemical specificity to measure the twenty common amino acids as pure substances. An unsolved challenge, however, is to quantify varying levels of amino acids mixed together and bound in soybeans at relatively low concentrations. Here we report the use of transmission Raman spectroscopy as a secondary analytical approach to nondestructively measure specific amino acids in intact soybeans. With the employment of a transmission-based Raman instrument, built specifically for nondestructive measurements from bulk soybeans, spectra were collected from twenty-four samples to develop a calibration model using a partial least-squares approach with a random-subset cross validation. The calibration model was validated on an independent set of twenty-five samples for oil, protein, and amino acid predictions. After Raman measurements, the samples were reduced to a fine powder and conventional wet chemistry methods were used for quantifying reference values of protein, oil, and 18 amino acids. We found that the greater the concentrations (% by weight component of interest), the better the calibration model and prediction capabilities. Of the 18 amino acids analyzed, 13 had R(2) values greater than 0.75 with a standard error of prediction c.a. 3-4% by weight. Serine, histidine, cystine, tryptophan, and methionine showed poor predictions (R(2) protein, oil, and specific amino acids in intact soybeans.

  10. Fourier transform Raman spectroscopy of polyacrylamide gels for radiation dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Baldock, C.; Murry, P.; Pope, J. [Queensland University of Tehchnology, Brisbane, QLD (Australia). Centres for Medical and Health Physics; Rintoul, L.; George, G. [Queensland University of Tehchnology, Brisbane, QLD (Australia). Instrumental and Development Chemistry


    Polyacrylamide (PAG) gels are used in magnetic resonance imaging radiation dosimetry. The PAG dosimeter is based on the radiation-induced co-polymerisation and cross-linking of acrylic monomers infused in a gel matrix. PAG was manufactured with a composition of 5% gelatine, 3% acrylamide and 3% N,N`methylene-bis-acrylamide by mass, with distilled water as the remaining constituent [Baldock, 1998]. FT-Raman spectroscopy studies were undertaken to investigate cross-linking changes during the co-polymerisation of PAG in the spectral range of 200 - 3500 cm{sup -1}. Vibrational bands of 1285 cm{sup -1} and 1256 cm{sup -1} were assigned to the acrylamide and bis-acrylamide single CH{sub 2} {delta}{sub CH2} binding modes. These bands were found to decrease in amplitude with increasing absorbed radiation dose, as a result of co-polymerisation. Principal Component Regression was performed on FT-Raman spectra of PAG samples irradiated to 50 Gy and two components were found to be sufficient to account for 98.7% of variance in the data. Cross validation was used to establish the absorbed radiation dose of an unknown PAG sample from the FT-Raman spectra. The calculated correlation coefficient between measured and predictive samples was 0.997 with a standard error of estimate of 0.976 and a standard error of prediction of 1.140. These results demonstrate the potential of FT-Raman spectroscopy for ionising radiation dosimetry using polyacrylamide gels

  11. Coral calcifying fluid aragonite saturation states derived from Raman spectroscopy (United States)

    DeCarlo, Thomas M.; D'Olivo, Juan P.; Foster, Taryn; Holcomb, Michael; Becker, Thomas; McCulloch, Malcolm T.


    Quantifying the saturation state of aragonite (ΩAr) within the calcifying fluid of corals is critical for understanding their biomineralization process and sensitivity to environmental changes including ocean acidification. Recent advances in microscopy, microprobes, and isotope geochemistry enable the determination of calcifying fluid pH and [CO32-], but direct quantification of ΩAr (where ΩAr = [CO32-][Ca2+]/Ksp) has proved elusive. Here we test a new technique for deriving ΩAr based on Raman spectroscopy. First, we analysed abiogenic aragonite crystals precipitated under a range of ΩAr from 10 to 34, and we found a strong dependence of Raman peak width on ΩAr with no significant effects of other factors including pH, Mg/Ca partitioning, and temperature. Validation of our Raman technique for corals is difficult because there are presently no direct measurements of calcifying fluid ΩAr available for comparison. However, Raman analysis of the international coral standard JCp-1 produced ΩAr of 12.3 ± 0.3, which we demonstrate is consistent with published skeletal Mg/Ca, Sr/Ca, B/Ca, δ11B, and δ44Ca data. Raman measurements are rapid ( ≤ 1 s), high-resolution ( ≤ 1 µm), precise (derived ΩAr ± 1 to 2 per spectrum depending on instrument configuration), accurate ( ±2 if ΩAr Great Barrier Reef, and we evaluate the response of ΩAr in juvenile Acropora cultured under elevated CO2 and temperature.

  12. Applications of Raman Spectroscopy in Biopharmaceutical Manufacturing: A Short Review. (United States)

    Buckley, Kevin; Ryder, Alan G


    The production of active pharmaceutical ingredients (APIs) is currently undergoing its biggest transformation in a century. The changes are based on the rapid and dramatic introduction of protein- and macromolecule-based drugs (collectively known as biopharmaceuticals) and can be traced back to the huge investment in biomedical science (in particular in genomics and proteomics) that has been ongoing since the 1970s. Biopharmaceuticals (or biologics) are manufactured using biological-expression systems (such as mammalian, bacterial, insect cells, etc.) and have spawned a large (>€35 billion sales annually in Europe) and growing biopharmaceutical industry (BioPharma). The structural and chemical complexity of biologics, combined with the intricacy of cell-based manufacturing, imposes a huge analytical burden to correctly characterize and quantify both processes (upstream) and products (downstream). In small molecule manufacturing, advances in analytical and computational methods have been extensively exploited to generate process analytical technologies (PAT) that are now used for routine process control, leading to more efficient processes and safer medicines. In the analytical domain, biologic manufacturing is considerably behind and there is both a huge scope and need to produce relevant PAT tools with which to better control processes, and better characterize product macromolecules. Raman spectroscopy, a vibrational spectroscopy with a number of useful properties (nondestructive, non-contact, robustness) has significant potential advantages in BioPharma. Key among them are intrinsically high molecular specificity, the ability to measure in water, the requirement for minimal (or no) sample pre-treatment, the flexibility of sampling configurations, and suitability for automation. Here, we review and discuss a representative selection of the more important Raman applications in BioPharma (with particular emphasis on mammalian cell culture). The review shows that

  13. Transcutaneous Measurement of Blood Analyte Concentration Using Raman Spectroscopy (United States)

    Barman, Ishan; Singh, Gajendra P.; Dasari, Ramachandra R.; Feld, Michael S.


    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.

  14. Ultrasensitive detection of phenolic antioxidants by surface enhanced Raman spectroscopy (United States)

    Ornelas-Soto, N.; Aguilar-Hernández, I. A.; Afseth, N.; López-Luke, T.; Contreras-Torres, F. F.; Wold, J. P.


    Surface-Enhanced Raman Spectroscopy (SERS) is a powerful surface-sensitive technique to study the vibrational properties of analytes at very low concentrations. In this study, ferulic acid, p-coumaric acid, caffeic acid and sinapic acid were analyzed by SERS using Ag colloids. Analytes were detected up to 2.5x10-9M. For caffeic acid and coumaric acid, this detection limit has been reached for the first time, as well as the SERS analysis of sinapic acid using silver colloids.

  15. Titania supported tungsten oxide species studied by Raman spectroscopy

    International Nuclear Information System (INIS)

    Han, Sang Hoon; Kim, Hack Sung; Kim, Kwan


    Laser Raman spectroscopy has been used to study the tungsta catalyst supported on titania. The surface tungsten species which forms on titania after calcination appeared to possess a structure that is independent of the initial impregnation condition. The surface polytungstate seemed to be stable only at the interfacial region since the crystalline WO 3 phase was observed as long as the tungsta loading was in excess of monolayer coverage. The close intact and strong interaction between the polytungstate and the titania could be evidenced from the inhibition of the phase transition of TiO 2 from anatase to rutile.(Author)

  16. Monitoring of blood oxygenation in brain by resonance Raman spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda A; Thomsen, Kirsten; Lønstrup, Micael


    Blood oxygenation in cerebral vessels is an essential parameter to evaluate brain function and to investigate the coupling between local blood flow and neuronal activity. We apply resonance Raman spectroscopy in vivo to study hemoglobin oxygenation in cortex vessels of anesthetized ventilated mice...... of oxyhemoglobin in venules, arterioles, and capillaries. In vivo measurements of blood oxygenation in the cortex of mice ventilated with inspiratory gas mixtures containing different amounts of oxygen - normoxia, hyperoxia and hypoxia - validate the proposed approach. Our method allows to visualize blood...

  17. Raman spectroscopy for the control of the atmospheric bioindicators (United States)

    Timchenko, E. V.; Timchenko, P. E.; Shamina, L. A.; Zherdeva, L. A.


    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.

  18. Transcutaneous monitoring of steroid-induced osteoporosis with Raman spectroscopy (United States)

    Maher, Jason R.; Inzana, Jason; Takahata, Masahiko; Awad, Hani A.; Berger, Andrew J.


    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.

  19. Optical characterization of semiconductors infrared, Raman, and photoluminescence spectroscopy

    CERN Document Server

    Perkowitz, Sidney


    This is the first book to explain, illustrate, and compare the most widely used methods in optics: photoluminescence, infrared spectroscopy, and Raman scattering. Written with non-experts in mind, the book develops the background needed to understand the why and how of each technique, but does not require special knowledge of semiconductors or optics. Each method is illustrated with numerous case studies. Practical information drawn from the authors experience is given to help establish optical facilities, including commercial sources for equipment, and experimental details. For industrial sci

  20. Tip-enhanced Raman spectroscopy for nanoscale strain characterization. (United States)

    Tarun, Alvarado; Hayazawa, Norihiko; Kawata, Satoshi


    Tip-enhanced Raman spectroscopy (TERS), which utilizes the strong localized optical field generated at the apex of a metallic tip when illuminated, has been shown to successfully probe the vibrational spectrum of today's and tomorrow's state-of-the-art silicon and next-generation semiconductor devices, such as quantum dots. Collecting and analyzing the vibrational spectrum not only aids in material identification but also provides insight into strain distributions in semiconductors. Here, the potential of TERS for nanoscale characterization of strain in silicon devices is reviewed. Emphasis will be placed on the key challenges of obtaining spectroscopic images of strain in actual strained silicon devices.

  1. Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy


    Yoon, Duhee; Son, Young-Woo; Cheong, Heonsik


    The thermal expansion coefficient (TEC) of single-layer graphene is estimated with temperature-dependent Raman spectroscopy in the temperature range between 200 and 400 K. It is found to be strongly dependent on temperature but remains negative in the whole temperature range, with a room temperature value of -8.0x10^{-6} K^{-1}. The strain caused by the TEC mismatch between graphene and the substrate plays a crucial role in determining the physical properties of graphene, and hence its effect...

  2. Negative thermal expansion coefficient of graphene measured by Raman spectroscopy. (United States)

    Yoon, Duhee; Son, Young-Woo; Cheong, Hyeonsik


    The thermal expansion coefficient (TEC) of single-layer graphene is estimated with temperature-dependent Raman spectroscopy in the temperature range between 200 and 400 K. It is found to be strongly dependent on temperature but remains negative in the whole temperature range with a room temperature value of (-8.0 ± 0.7) × 10(-6) K(-1). The strain caused by the TEC mismatch between graphene and the substrate plays a crucial role in determining the physical properties of graphene, and hence its effect must be accounted for in the interpretation of experimental data taken at cryogenic or elevated temperatures.

  3. Characterization of oil-producing microalgae using Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Samek, Ota; Zemánek, Pavel; Jonáš, Alexandr; Telle, H.H.


    Roč. 8, č. 10 (2011), s. 701-709 ISSN 1612-2011 R&D Projects: GA MŠk OC08034; GA MŠk ED0017/01/01; GA ČR GAP205/11/1687 Grant - others:EC(XE) PERG 06-GA-2009-256526 Institutional research plan: CEZ:AV0Z20650511 Keywords : Raman spectroscopy * algae * lipids * biofuel * iodine value * microorganisms Subject RIV: BH - Optics, Masers, Lasers Impact factor: 9.970, year: 2011

  4. Chemotaxonomy of mints of genus Mentha by applying Raman spectroscopy. (United States)

    Rösch, P; Kiefer, W; Popp, J


    The characterization of mints is often problematic because Mentha is a taxonomically complex genus. In order to provide a fast and easy characterization method, we use a combination of micro-Raman spectroscopy and hierarchical cluster analysis. A classification trial of different mint taxa is possible for one collection time. For spectra measured at different points during the growing season, a more sophisticated pretreatment of the data is necessary to receive good discrimination between the species, as well as between the subspecies and varieties of the mints. Copyright 2002 Wiley Periodicals, Inc.

  5. Combination of laser-induced breakdown spectroscopy and Raman spectroscopy for multivariate classification of bacteria (United States)

    Prochazka, D.; Mazura, M.; Samek, O.; Rebrošová, K.; Pořízka, P.; Klus, J.; Prochazková, P.; Novotný, J.; Novotný, K.; Kaiser, J.


    In this work, we investigate the impact of data provided by complementary laser-based spectroscopic methods on multivariate classification accuracy. Discrimination and classification of five Staphylococcus bacterial strains and one strain of Escherichia coli is presented. The technique that we used for measurements is a combination of Raman spectroscopy and Laser-Induced Breakdown Spectroscopy (LIBS). Obtained spectroscopic data were then processed using Multivariate Data Analysis algorithms. Principal Components Analysis (PCA) was selected as the most suitable technique for visualization of bacterial strains data. To classify the bacterial strains, we used Neural Networks, namely a supervised version of Kohonen's self-organizing maps (SOM). We were processing results in three different ways - separately from LIBS measurements, from Raman measurements, and we also merged data from both mentioned methods. The three types of results were then compared. By applying the PCA to Raman spectroscopy data, we observed that two bacterial strains were fully distinguished from the rest of the data set. In the case of LIBS data, three bacterial strains were fully discriminated. Using a combination of data from both methods, we achieved the complete discrimination of all bacterial strains. All the data were classified with a high success rate using SOM algorithm. The most accurate classification was obtained using a combination of data from both techniques. The classification accuracy varied, depending on specific samples and techniques. As for LIBS, the classification accuracy ranged from 45% to 100%, as for Raman Spectroscopy from 50% to 100% and in case of merged data, all samples were classified correctly. Based on the results of the experiments presented in this work, we can assume that the combination of Raman spectroscopy and LIBS significantly enhances discrimination and classification accuracy of bacterial species and strains. The reason is the complementarity in

  6. An integrated coherent anti-Stokes Raman scattering and multiphoton imaging technique for liver disease diagnosis (United States)

    Lin, Jian; Lu, Fake; Zheng, Wei; Yu, Hanry; Sheppard, Colin; Huang, Zhiwei


    Liver steatosis and fibrosis are two prevalence liver diseases and may eventually develop into hepatocellular carcinoma (HCC) Due to their prevalence and severity, much work has been done to develop efficient diagnostic methods and therapies. Nonlinear optical microscopy has high sensitivity and chemical specificity for major biochemical compounds, making it a powerful tool for tissue imaging without staining. In this study, three nonlinear microscopy imaging modalities are applied to the study of liver diseases in a bile duct ligation rat modal. CARS shows the distributions of fats or lipids quantitatively across the tissue; SHG visualizes the collagens; and TPEF reveals the morphology of hepatic cells. The results clearly show the development of liver steatosis and fibrosis with time, and the hepatic fat and collagen fibrils are quantified. This study demonstrates the ability of multimodal nonlinear optical microscopy for liver disease diagnosis, and may provide new insights into the understanding of the mechanisms of steatosis/fibrosis transformations at the cellular and molecular levels.

  7. In situ dissolution analysis using coherent anti-Stokes Raman scattering (CARS) and hyperspectral CARS microscopy

    NARCIS (Netherlands)

    Fussell, A.L.; Garbacik, E.T.; Offerhaus, Herman L.; Kleinebudde, Peter; Strachan, Clare


    The solid-state form of an active pharmaceutical ingredient (API) in an oral dosage form plays an important role in determining the dissolution rate of the API. As the solid-state form can change during dissolution, there is a need to monitor the oral dosage form during dissolution testing. Coherent

  8. Analysis of detection limit to time-resolved coherent anti-Stokes Raman scattering nanoscopy

    International Nuclear Information System (INIS)

    Liu Wei; Liu Shuang-Long; Chen Dan-Ni; Niu Han-Ben


    In the implementation of CARS nanoscopy, signal strength decreases with focal volume size decreasing. A crucial problem that remains to be solved is whether the reduced signal generated in the suppressed focal volume can be detected. Here reported is a theoretical analysis of detection limit (DL) to time-resolved CARS (T-CARS) nanoscopy based on our proposed additional probe-beam-induced phonon depletion (APIPD) method for the low concentration samples. In order to acquire a detailed shot-noise limited signal-to-noise (SNR) and the involved parameters to evaluate DL, the T-CARS process is described with full quantum theory to estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons, which are both actually on the order of ∼ 10 9 W/cm 2 . When the pump and Stokes intensities reach such values and the total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in a certain suppressed focal volume (40-nm suppressed focal scale in APIPD method), the DL correspondingly varies with exposure time, for example, DL values are 10 3 and 10 2 when exposure times are 20 ms and 200 ms respectively. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  9. Precise determination of graphene functionalization by in situ Raman spectroscopy (United States)

    Vecera, Philipp; Chacón-Torres, Julio C.; Pichler, Thomas; Reich, Stephanie; Soni, Himadri R.; Görling, Andreas; Edelthalhammer, Konstantin; Peterlik, Herwig; Hauke, Frank; Hirsch, Andreas


    The verification of a successful covalent functionalization of graphene and related carbon allotropes can easily be carried out by Raman spectroscopy. Nevertheless, the unequivocal assignment and resolution of individual lattice modes associated with the covalent binding of addends was elusive up to now. Here we present an in situ Raman study of a controlled functionalization of potassium intercalated graphite, revealing several new bands appearing in the D-region of the spectrum. The evolution of these bands with increasing degree of functionalization from low to moderate levels provides a basis for the deconvolution of the different components towards quantifying the extent of functionalization. By complementary DFT calculations we were able to identify the vibrational changes in the close proximity of the addend bearing lattice carbon atoms and to assign them to specific Raman modes. The experimental in situ observation of the developing functionalization along with the reoxidation of the intercalated graphite represents an important step towards an improved understanding of the chemistry of graphene. PMID:28480893

  10. Cryoprotectant redistribution along the frozen straw probed by Raman spectroscopy. (United States)

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


    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. Copyright © 2016 Elsevier Inc. All rights reserved.

  11. Antenna Design for Directivity-Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Aftab Ahmed


    Full Text Available Antenna performance can be described by two fundamental parameters: directivity and radiation efficiency. Here, we demonstrate nanoantenna designs in terms of improved directivity. Performance of the antennas is demonstrated in Raman scattering experiments. The radiated beam is directed out of the plane by using a ground plane reflector for easy integration with commercial microscopes. Parasitic elements and parabolic and waveguide nanoantennas with a ground plane are explored. The nanoantennas were fabricated by a series of electron beam evaporation steps and focused ion beam milling. As we have shown previously, the circular waveguide nanoantenna boosts the measured Raman signal by 5.5x with respect to a dipole antenna over a ground plane; here, we present the design process that led to the development of that circular waveguide nanoantenna. This work also shows that the parabolic nanoantenna produces a further fourfold improvement in the measured Raman signal with respect to a circular waveguide nanoantenna. The present designs are nearly optimal in the sense that almost all the beam power is coupled into the numerical aperture of the microscope. These designs can find applications in microscopy, spectroscopy, light-emitting devices, photovoltaics, single-photon sources, and sensing.

  12. A novel extremophile strategy studied by Raman spectroscopy (United States)

    Edwards, Howell G. M.


    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.

  13. A Novel Method for Bacterial UTI Diagnosis Using Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Evdokia Kastanos


    Full Text Available The current state of the art on bacterial classification using Raman and Surface Enhanced Raman Spectroscopy (SERS for the purpose of developing a rapid and more accurate method for urinary tract infection (UTI diagnosis is presented. SERS, an enhanced version of Raman offering much increased sensitivity, provides complex biochemical information which, in conjunction with advanced analysis and classification techniques, can become a valuable diagnostic tool. The variety of metal substrates used for SERS, including silver and gold colloids, as well as nanostructured metal surfaces, is reviewed. The challenges in preprocessing noisy and complicated spectra and the various methods used for feature creation as well as a novel method using spectral band ratios are described. The various unsupervised and supervised classification methods commonly used for SERS spectra of bacteria are evaluated. Current research on transforming SERS into a valuable clinical tool for the diagnosis of UTIs is presented. Specifically, the classification of bacterial spectra (a as positive or negative for an infection, (b as belonging to a particular species of bacteria, and (c as sensitive or resistant to an antibiotic are described. This work can lead to the development of novel technology with extremely important benefits for public health.

  14. Terahertz mechanical vibrations in lysozyme: Raman spectroscopy vs modal analysis (United States)

    Carpinteri, Alberto; Lacidogna, Giuseppe; Piana, Gianfranco; Bassani, Andrea


    The mechanical behaviour of proteins is receiving an increasing attention from the scientific community. Recently it has been suggested that mechanical vibrations play a crucial role in controlling structural configuration changes (folding) which govern proteins biological function. The mechanism behind protein folding is still not completely understood, and many efforts are being made to investigate this phenomenon. Complex molecular dynamics simulations and sophisticated experimental measurements are conducted to investigate protein dynamics and to perform protein structure predictions; however, these are two related, although quite distinct, approaches. Here we investigate mechanical vibrations of lysozyme by Raman spectroscopy and linear normal mode calculations (modal analysis). The input mechanical parameters to the numerical computations are taken from the literature. We first give an estimate of the order of magnitude of protein vibration frequencies by considering both classical wave mechanics and structural dynamics formulas. Afterwards, we perform modal analyses of some relevant chemical groups and of the full lysozyme protein. The numerical results are compared to experimental data, obtained from both in-house and literature Raman measurements. In particular, the attention is focused on a large peak at 0.84 THz (29.3 cm-1) in the Raman spectrum obtained analyzing a lyophilized powder sample.

  15. Searching for brine on Mars using Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fischer, E.


    In the last few years, water ice and perchlorate salts capable of melting this ice and producing liquid solutions have been discovered at the surface and shallow subsurface of Mars. In addition to via melting of ice, perchlorate salts may also form liquid solutions by absorbing water vapor when the relative humidity is above a certain threshold in a process known as deliquescence. Formed either by melting or deliquescence, liquid solutions (brine) are the most likely way of liquid water activity on the Martian surface and in the shallow subsurface and are therefore important to understand the habitability of Mars. Using Raman spectroscopy, we provide reference spectra of various mixing states of liquid water, water ice and calcium perchlorate, all of which can occur during brine formation. We focus on the perchlorate symmetric stretching band and the O-H stretching vibrational band to distinguish brine from crystalline salt and water ice. We show that perchlorate brines can be identified by analyzing the peaks and their widths in the decomposed Raman spectra of the investigated samples. This serves as an important reference for future in-situ Raman spectrometers on Mars, such as those on the ExoMars and Mars 2020 rovers and can aid in the detection of brine formation on Mars. (Author)

  16. Silicon Nitride Background in Nanophotonic Waveguide Enhanced Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Ashim Dhakal


    Full Text Available Recent studies have shown that evanescent Raman spectroscopy using a silicon nitride (SiN nanophotonic waveguide platform has higher signal enhancement when compared to free-space systems. However, signal-to-noise ratio from the waveguide at a low analyte concentration is constrained by the shot-noise from the background light originating from the waveguide itself. Hence, understanding the origin and properties of this waveguide background luminescence (WGBL is essential to developing mitigation strategies. Here, we identify the dominating component of the WGBL spectrum composed of a broad Raman scattering due to momentum selection-rule breaking in amorphous materials, and several peaks specific to molecules embedded in the core. We determine the maximum of the Raman scattering efficiency of the WGBL at room temperature for 785 nm excitation to be 4.5 ± 1 × 10−9 cm−1·sr−1, at a Stokes shift of 200 cm−1. This efficiency decreases monotonically for higher Stokes shifts. Additionally, we also demonstrate the use of slotted waveguides and quasi-transverse magnetic polarization as some mitigation strategies.

  17. Raman Spectroscopy and in Situ Raman Spectroelectrochemistry of Bilayer 12C/13C Graphene

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Farhat, H.; Kong, J.; Janda, Pavel; Kavan, Ladislav; Dresselhaus, M. S.


    Roč. 11, č. 5 (2011), s. 1957-1963 ISSN 1530-6984 R&D Projects: GA AV ČR IAA400400911; GA AV ČR IAA400400804; GA AV ČR KAN200100801; GA MŠk ME09060; GA MŠk LC510; GA ČR GC203/07/J067; GA ČR GAP204/10/1677 Institutional research plan: CEZ:AV0Z40400503 Keywords : graphene * bilayer * Raman Spectroscopy Subject RIV: CG - Electrochemistry Impact factor: 13.198, year: 2011


    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...

  19. Novel Chiroptical Analysis of Hemoglobin by Surface Enhanced Resonance Raman Optical Activity Spectroscopy

    DEFF Research Database (Denmark)

    Brazhe, Nadezda; Brazhe, Alexey; Sosnovtseva, Olga


    The metalloprotein hemoglobin (Hb) was studied using surface enhanced resonance Raman spectroscopy (SERRS) and surface enhanced resonance Raman optical activity (SERROA). The SERROA results are analyzed and compared with the SERRS, and the later to the resonance Raman (RRS) performed on Hb...

  20. Photoluminescence and Raman Spectroscopy Studies of Carbon Nitride Films

    Directory of Open Access Journals (Sweden)

    J. Hernández-Torres


    Full Text Available Amorphous carbon nitride films with N/C ratios ranging from 2.24 to 3.26 were deposited by reactive sputtering at room temperature on corning glass, silicon, and quartz as substrates. The average chemical composition of the films was obtained from the semiquantitative energy dispersive spectroscopy analysis. Photoluminescence measurements were performed to determine the optical band gap of the films. The photoluminescence spectra displayed two peaks: one associated with the substrate and the other associated with CNx films located at ≈2.13±0.02 eV. Results show an increase in the optical band gap from 2.11 to 2.15 eV associated with the increase in the N/C ratio. Raman spectroscopy measurements showed a dominant D band. ID/IG ratio reaches a maximum value for N/C ≈ 3.03 when the optical band gap is 2.12 eV. Features observed by the photoluminescence and Raman studies have been associated with the increase in the carbon sp2/sp3 ratio due to presence of high nitrogen content.

  1. Machine learning methods for quantitative analysis of Raman spectroscopy data (United States)

    Madden, Michael G.; Ryder, Alan G.


    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.

  2. UV photostability of insect repellents evaluated through Raman spectroscopy (United States)

    Bório, Viviane G.; Fernandes, Adjaci U.; Silveira, Landulfo


    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.

  3. Evaluation of bone quality in osteoporosis model mice by Raman spectroscopy (United States)

    Ishimaru, Yasumitsu; Oshima, Yusuke; Imai, Yuuki; Iimura, Tadahiro; Takanezawa, Sota; Hino, Kazunori; Miura, Hiromasa


    To evaluate the bone quality in the osteoporosis, we generated sciatic nerve resection (NX) mice as an osteoporosis model and analyzed by Raman spectroscopy. Raman spectra were measured in anterior cortical surface of the proximal tibia at 5 points in each bone. After that, the samples were fixed with 70% ethanol. We then performed DXA and μCT measurement. Raman peak intensity ratios were significantly different between NX and Control. Those changes in the Raman peak intensity ratios may reflect loss of bone quality in the osteoporosis model. Raman spectroscopy is a promising technique for measuring the bone quality and bone strength.

  4. Multi-excitation Raman difference spectroscopy based on modified multi-energy constrained iterative deconvolution algorithm (United States)

    Zou, Wenlong; Cai, Zhijian; Zhou, Hongwu; Wu, Jianhong


    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.

  5. Near-infrared spectroscopy for cocrystal screening. A comparative study with Raman spectroscopy. (United States)

    Allesø, Morten; Velaga, Sitaram; Alhalaweh, Amjad; Cornett, Claus; Rasmussen, Morten A; van den Berg, Frans; de Diego, Heidi Lopez; Rantanen, Jukka


    Near-infrared (NIR) spectroscopy is a well-established technique for solid-state analysis, providing fast, noninvasive measurements. The use of NIR spectroscopy for polymorph screening and the associated advantages have recently been demonstrated. The objective of this work was to evaluate the analytical potential of NIR spectroscopy for cocrystal screening using Raman spectroscopy as a comparative method. Indomethacin was used as the parent molecule, while saccharin and l-aspartic acid were chosen as guest molecules. Molar ratios of 1:1 for each system were subjected to two types of preparative methods. In the case of saccharin, liquid-assisted cogrinding as well as cocrystallization from solution resulted in a stable 1:1 cocrystalline phase termed IND-SAC cocrystal. For l-aspartic acid, the solution-based method resulted in a polymorphic transition of indomethacin into the metastable alpha form retained in a physical mixture with the guest molecule, while liquid-assisted cogrinding did not induce any changes in the crystal lattice. The good chemical peak selectivity of Raman spectroscopy allowed a straightforward interpretation of sample data by analyzing peak positions and comparing to those of pure references. In addition, Raman spectroscopy provided additional information on the crystal structure of the IND-SAC cocrystal. The broad spectral line shapes of NIR spectra make visual interpretation of the spectra difficult, and consequently, multivariate modeling by principal component analysis (PCA) was applied. Successful use of NIR/PCA was possible only through the inclusion of a set of reference mixtures of parent and guest molecules representing possible solid-state outcomes from the cocrystal screening. The practical hurdle related to the need for reference mixtures seems to restrict the applicability of NIR spectroscopy in cocrystal screening.

  6. Surface enhanced Raman spectroscopy: A review of recent applications in forensic science (United States)

    Fikiet, Marisia A.; Khandasammy, Shelby R.; Mistek, Ewelina; Ahmed, Yasmine; Halámková, Lenka; Bueno, Justin; Lednev, Igor K.


    Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics.

  7. Profiling of liquid crystal displays with Raman spectroscopy: preprocessing of spectra

    NARCIS (Netherlands)

    Stanimirovic, Olja; Boelens, Hans F. M.; Mank, Arjan J. G.; Hoefsloot, Huub C. J.; Smilde, Age K.


    Raman spectroscopy is applied for characterizing paintable displays. Few other options than Raman spectroscopy exist for doing so because of the liquid nature of functional materials. The challenge is to develop a method that can be used for estimating the composition of a single display cell on the

  8. Profiling of liquid crystal displays with Raman spectroscopy: Preprocessing of spectra.

    NARCIS (Netherlands)

    Stanimirovic, O.; Boelens, H.F.M.; Mank, A.J.G.; Hoefsloot, H.C.J.; Smilde, A.K.


    Raman spectroscopy is applied for characterizing paintable displays. Few other options than Raman spectroscopy exist for doing so because of the liquid nature of functional materials. The challenge is to develop a method that can be used for estimating the composition of a single display cell on the

  9. [Research Progress of Raman Spectroscopy on Dyestuff Identification of Ancient Relics and Artifacts]. (United States)

    He, Qiu-ju; Wang, Li-qin


    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.

  10. Coral calcifying fluid aragonite saturation states derived from Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    T. M. DeCarlo


    Full Text Available Quantifying the saturation state of aragonite (ΩAr within the calcifying fluid of corals is critical for understanding their biomineralization process and sensitivity to environmental changes including ocean acidification. Recent advances in microscopy, microprobes, and isotope geochemistry enable the determination of calcifying fluid pH and [CO32−], but direct quantification of ΩAr (where ΩAr =  [CO32−][Ca2+]∕Ksp has proved elusive. Here we test a new technique for deriving ΩAr based on Raman spectroscopy. First, we analysed abiogenic aragonite crystals precipitated under a range of ΩAr from 10 to 34, and we found a strong dependence of Raman peak width on ΩAr with no significant effects of other factors including pH, Mg∕Ca partitioning, and temperature. Validation of our Raman technique for corals is difficult because there are presently no direct measurements of calcifying fluid ΩAr available for comparison. However, Raman analysis of the international coral standard JCp-1 produced ΩAr of 12.3 ± 0.3, which we demonstrate is consistent with published skeletal Mg∕Ca, Sr∕Ca, B∕Ca, δ11B, and δ44Ca data. Raman measurements are rapid ( ≤  1 s, high-resolution ( ≤  1 µm, precise (derived ΩAr ± 1 to 2 per spectrum depending on instrument configuration, accurate ( ±2 if ΩAr < 20, and require minimal sample preparation, making the technique well suited for testing the sensitivity of coral calcifying fluid ΩAr to ocean acidification and warming using samples from natural and laboratory settings. To demonstrate this, we also show a high-resolution time series of ΩAr over multiple years of growth in a Porites skeleton from the Great Barrier Reef, and we evaluate the response of ΩAr in juvenile Acropora cultured under elevated CO2 and temperature.

  11. Identification of anisodamine tablets by Raman and near-infrared spectroscopy with chemometrics. (United States)

    Li, Lian; Zang, Hengchang; Li, Jun; Chen, Dejun; Li, Tao; Wang, Fengshan


    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. Copyright © 2014 Elsevier B.V. All rights reserved.

  12. Near-infrared-excited confocal Raman spectroscopy advances in vivo diagnosis of cervical precancer. (United States)

    Duraipandian, Shiyamala; Zheng, Wei; Ng, Joseph; Low, Jeffrey J H; Ilancheran, Arunachalam; Huang, Zhiwei


    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%, (pspectroscopy 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.

  13. Surface enhanced Raman spectroscopy on a flat graphene surface (United States)

    Xu, Weigao; Ling, Xi; Xiao, Jiaqi; Dresselhaus, Mildred S.; Kong, Jing; Xu, Hongxing; Liu, Zhongfan; Zhang, Jin


    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

  14. Classification of oral cancers using Raman spectroscopy of serum (United States)

    Sahu, Aditi; Talathi, Sneha; Sawant, Sharada; Krishna, C. Murali


    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.

  15. Probing of different conformations of piperazine using Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    SenGupta, Sumana, E-mail:; Maiti, Nandita, E-mail:; Chadha, Ridhima; Kapoor, Sudhir


    Graphical abstract: - Highlights: • Most stable conformation of piperazine molecule is equatorial–equatorial chair form. • Equatorial–equatorial chair form is predominant in pure solid. • Strongly dipolar equatorial–axial form is most stabilized in aqueous solution. • Equatorial–axial form vertically binds to Ag/Ag{sup +} through axial N-atom. - Abstract: 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{sup −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.

  16. Two-step Raman spectroscopy method for tumor diagnosis (United States)

    Zakharov, V. P.; Bratchenko, I. A.; Kozlov, S. V.; Moryatov, A. A.; Myakinin, O. O.; Artemyev, D. N.


    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).

  17. Probing charged impurities in suspended graphene using Raman spectroscopy. (United States)

    Ni, Zhen Hua; Yu, Ting; Luo, Zhi Qiang; Wang, Ying Ying; Liu, Lei; Wong, Choun Pei; Miao, Jianmin; Huang, Wei; Shen, Ze Xiang


    Charged impurity (CI) scattering is one of the dominant factors that affects the carrier mobility in graphene. In this paper, we use Raman spectroscopy to probe the charged impurities in suspended graphene. We find that the 2D band intensity is very sensitive to the CI concentration in graphene, while the G band intensity is not affected. The intensity ratio between the 2D and G bands, I(2D)/I(G), of suspended graphene is much stronger compared to that of nonsuspended graphene, due to the extremely low CI concentration in the former. This finding is consistent with the ultrahigh carrier mobility in suspended graphene observed in recent transport measurements. Our results also suggest that at low CI concentrations that are critical for device applications, the I(2D)/I(G) ratio is a better criterion in selecting high quality single layer graphene samples than is the G band blue shift.

  18. High-pressure Raman spectroscopy of phase change materials

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, Wen-Pin, E-mail:; Mao, Wendy L. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Zalden, Peter [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Wuttig, Matthias [I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen (Germany); JARA – Fundamentals of Future Information Technology, RWTH Aachen University, 52056 Aachen (Germany); Lindenberg, Aaron M. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); SLAC National Accelerator Laboratory, PULSE Institute, Menlo Park, California 94025 (United States)


    We used high-pressure Raman spectroscopy to study the evolution of vibrational frequencies of the phase change materials (PCMs) Ge{sub 2}Sb{sub 2}Te{sub 5}, GeSb{sub 2}Te{sub 4}, and SnSb{sub 2}Te{sub 4}. We found that the critical pressure for triggering amorphization in the PCMs decreases with increasing vacancy concentration, demonstrating that the presence of vacancies, rather than differences in the atomic covalent radii, is crucial for pressure-induced amorphization in PCMs. Compared to the as-deposited amorphous phase, the pressure-induced amorphous phase has a similar vibrational spectrum but requires much lower laser power to transform into the crystalline phase, suggesting different kinetics of crystallization, which may have implications for applications of PCMs in non-volatile data storage.

  19. Monitoring the healing process of rat bones using Raman spectroscopy (United States)

    Gamulin, O.; Serec, K.; Bilić, V.; Balarin, M.; Kosović, M.; Drmić, D.; Brčić, L.; Seiwerth, S.; Sikirić, P.


    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.

  20. Engineering Plasmonic Nanopillar Arrays for Surface-enhanced Raman Spectroscopy

    DEFF Research Database (Denmark)

    Wu, Kaiyu

    This Ph.D. thesis presents (i) an in-depth understanding of the localized surface plasmon resonances (LSPRs) in the nanopillar arrays (NPs) for surface-enhanced Raman spectroscopy (SERS), and (ii) systematic ways of optimizing the fabrication process of NPs to improve their SERS efficiencies.......e., the particle mode and the cavity mode. The particle mode can be hybridized via leaning of pillars. The LSPR wavelength of the cavity mode is dominant only by the diameter of the Si pillar. The presence of a substrate dramatically changes the intensities of these two LSPR modes, by introducing constructive...... displaying a very large average SERS EF of >108. From a practical point of view, the developed SERS substrates are particularity interesting, since they are easy to handle and store and the fabrication is scalable, facilitating a wide and simple use of SERS in sensing applications....

  1. Horizontal silicon nanowires for surface-enhanced Raman spectroscopy (United States)

    Gebavi, Hrvoje; Ristić, Davor; Baran, Nikola; Mikac, Lara; Mohaček-Grošev, Vlasta; Gotić, Marijan; Šikić, Mile; Ivanda, Mile


    The main purpose of this paper is to focus on details of the fabrication process of horizontally and vertically oriented silicon nanowires (SiNWs) substrates for the application of surface-enhanced Raman spectroscopy (SERS). The fabrication process is based on the vapor-liquid-solid method and electroless-assisted chemical etching, which, as the major benefit, resulting in the development of economical, easy-to-prepare SERS substrates. Furthermore, we examined the fabrication of Au coated Ag nanoparticles (NPs) on the SiNWs substrates in such a way as to diminish the influence of silver NPs corrosion, which, in turn, enhanced the SERS time stability, thus allowing for wider commercial applications. The substances on which high SERS sensitivity was proved are rhodamine (R6G) and 4-mercaptobenzoic acid (MBA), with the detection limits of 10-8 M and 10-6 M, respectively.

  2. High-pressure polymorphism of acetylsalicylic acid (aspirin): Raman spectroscopy (United States)

    Crowell, Ethan L.; Dreger, Zbigniew A.; Gupta, Yogendra M.


    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.

  3. Confocal mapping of myelin figures with micro-Raman spectroscopy (United States)

    Huang, Jung-Ren; Cheng, Yu-Che; Huang, Hung Ji; Chiang, Hai-Pang


    We employ confocal micro-Raman spectroscopy (CMRS) with submicron spatial resolution to study the myelin structures (cylindrical lamellae) composed of nested surfactant C12E3 or lipid DMPC bilayers. The CMRS mapping indicates that for a straight C12E3 myelin, the surfactant concentration increases with the myelin width and is higher in the center region than in the peripheral region. For a curved C12E3 myelin, the convex side has a higher surfactant concentration than the corresponding concave side. The spectrum of DMPC myelins undergoes a qualitative change as the temperature increases above 60 °C, suggesting that the surfactant molecules may be damaged. Our work demonstrates the utility of CMRS in bio-soft material research.

  4. Optimization of Sample Preparation processes of Bone Material for Raman Spectroscopy. (United States)

    Chikhani, Madelen; Wuhrer, Richard; Green, Hayley


    Raman spectroscopy has recently been investigated for use in the calculation of postmortem interval from skeletal material. The fluorescence generated by samples, which affects the interpretation of Raman data, is a major limitation. This study compares the effectiveness of two sample preparation techniques, chemical bleaching and scraping, in the reduction of fluorescence from bone samples during testing with Raman spectroscopy. Visual assessment of Raman spectra obtained at 1064 nm excitation following the preparation protocols indicates an overall reduction in fluorescence. Results demonstrate that scraping is more effective at resolving fluorescence than chemical bleaching. The scraping of skeletonized remains prior to Raman analysis is a less destructive method and allows for the preservation of a bone sample in a state closest to its original form, which is beneficial in forensic investigations. It is recommended that bone scraping supersedes chemical bleaching as the preferred method for sample preparation prior to Raman spectroscopy. © 2018 American Academy of Forensic Sciences.

  5. Advances in Raman spectroscopy for the diagnosis of Alzheimer's disease (United States)

    Sudworth, Caroline D.; Archer, John K. J.; Black, Richard A.; Mann, David


    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.

  6. Raman spectroscopy and in situ Raman spectroelectrochemistry of isotopically engineered graphene systems. (United States)

    Frank, Otakar; Dresselhaus, Mildred S; Kalbac, Martin


    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

  7. Raman and surface-enhanced Raman spectroscopy of amino acids and nucleotide bases for target bacterial vibrational mode identification (United States)

    Guicheteau, Jason; Argue, Leanne; Hyre, Aaron; Jacobson, Michele; Christesen, Steven D.


    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.

  8. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers

    DEFF Research Database (Denmark)

    Perozziello, Gerardo; Candeloro, Patrizio; De Grazia, Antonio


    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels-where the cells can flow one-by-one -, allowing single...... cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm...

  9. Raman spectroscopy of boron-doped single-layer graphene. (United States)

    Kim, Yoong Ahm; Fujisawa, Kazunori; Muramatsu, Hiroyuki; Hayashi, Takuya; Endo, Morinobu; Fujimori, Toshihiko; Kaneko, Katsumi; Terrones, Mauricio; Behrends, Jan; Eckmann, Axel; Casiraghi, Cinzia; Novoselov, Kostya S; Saito, Riichiro; Dresselhaus, Mildred S


    The introduction of foreign atoms, such as nitrogen, into the hexagonal network of an sp(2)-hybridized carbon atom monolayer has been demonstrated and constitutes an effective tool for tailoring the intrinsic properties of graphene. Here, we report that boron atoms can be efficiently substituted for carbon in graphene. Single-layer graphene substitutionally doped with boron was prepared by the mechanical exfoliation of boron-doped graphite. X-ray photoelectron spectroscopy demonstrated that the amount of substitutional boron in graphite was ~0.22 atom %. Raman spectroscopy demonstrated that the boron atoms were spaced 4.76 nm apart in single-layer graphene. The 7-fold higher intensity of the D-band when compared to the G-band was explained by the elastically scattered photoexcited electrons by boron atoms before emitting a phonon. The frequency of the G-band in single-layer substitutionally boron-doped graphene was unchanged, which could be explained by the p-type boron doping (stiffening) counteracting the tensile strain effect of the larger carbon-boron bond length (softening). Boron-doped graphene appears to be a useful tool for engineering the physical and chemical properties of graphene.

  10. Dual-modal cancer detection based on optical pH sensing and Raman spectroscopy (United States)

    Kim, Soogeun; Lee, Seung Ho; Min, Sun Young; Byun, Kyung Min; Lee, Soo Yeol


    A dual-modal approach using Raman spectroscopy and optical pH sensing was investigated to discriminate between normal and cancerous tissues. Raman spectroscopy has demonstrated the potential for in vivo cancer detection. However, Raman spectroscopy has suffered from strong fluorescence background of biological samples and subtle spectral differences between normal and disease tissues. To overcome those issues, pH sensing is adopted to Raman spectroscopy as a dual-modal approach. Based on the fact that the pH level in cancerous tissues is lower than that in normal tissues due to insufficient vasculature formation, the dual-modal approach combining the chemical information of Raman spectrum and the metabolic information of pH level can improve the specificity of cancer diagnosis. From human breast tissue samples, Raman spectra and pH levels are measured using fiber-optic-based Raman and pH probes, respectively. The pH sensing is based on the dependence of pH level on optical transmission spectrum. Multivariate statistical analysis is performed to evaluate the classification capability of the dual-modal method. The analytical results show that the dual-modal method based on Raman spectroscopy and optical pH sensing can improve the performance of cancer classification.

  11. Two-photon-excited fluorescence spectroscopy of atomic fluorine at 170 nm (United States)

    Herring, G. C.; Dyer, Mark J.; Jusinski, Leonard E.; Bischel, William K.


    Two-photon-excited fluorescence spectroscopy of atomic fluorine is reported. A doubled dye laser at 286-nm is Raman shifted in H2 to 170 nm (sixth anti-Stokes order) to excite ground-state 2P(0)J fluorine atoms to the 2D(0)J level. The fluorine atoms are detected by one of two methods: observing the fluorescence decay to the 2PJ level or observing F(+) production through the absorption of an additional photon by the excited atoms. Relative two-photon absorption cross sections to and the radiative lifetimes of the 2D(0)J states are measured.

  12. CARS spectroscopy of the (v=0 \\rightarrow 1) band in {{{\\rm{T}}}_{2}}_{} (United States)

    Schlösser, M.; Zhao, X.; Trivikram, M.; Ubachs, W.; Salumbides, E. J.


    Molecular hydrogen is a benchmark system for bound state quantum calculation and tests of quantum electrodynamical effects. While spectroscopic measurements on the stable species have progressively improved over the years, high-resolution studies on the radioactive isotopologues {{{T}}}2, {HT} and {DT} have been limited. Here we present an accurate determination of T2 Q(J=0{--}5) transition energies in the fundamental vibrational band of the ground electronic state, by means of high-resolution coherent anti-Stokes Raman spectroscopy. With the present experimental uncertainty of 0.02 {{cm}}-1, which is a fivefold improvement over previous measurements, agreement with the latest theoretical calculations is demonstrated.

  13. Application of Raman Spectroscopy for Quality Monitoring in the Meat Processing Industry

    DEFF Research Database (Denmark)

    Berhe, Daniel Tsegay

    The objective of this thesis was to test the potential application of Raman spectroscopy for quality monitoring in the meat processing industry. Raman spectroscopy is a spectroscopic technique, which can provide rapid chemical information at the molecular level. It can, therefore, be used for non......-destructive quality monitoring in the meat processing industry as it requires no further sample preparation. Water, which is the main component of meat, is also not a problem for Raman spectroscopic measurement because water is a poor Raman scatter. Two major product quality related issues, cooking of meat and fat...... in water bath then stored under vacuum packaging for day- 0, -4 and -8 (paper-II). Secondly, the thesis work examined the use of Raman spectroscopy in combination with chemometrics to determine the gross FA parameters and individual FAs in pork backfat. Non-targeted predictions of highly collinear...

  14. Calibration Transfer in LIBS and Raman Spectroscopy for Planetary Applications (United States)

    Dyar, M. D.; Thomas, B. F.; Parente, M.; Gemp, I.; Mullen, T. H.


    Planetary scientists rely on spectral libraries and instrument reproducibility to interpret results from missions. Major investments have been made into assembling libraries, but they often naively assume that spectra of single crystals versus powders and from varying instruments will be the same. Calibration transfer (CT) seeks to algorithmically resolve discrepancies among datasets from different instruments or conditions. It offers the ability to align suites of spectra with a small number of common samples, allowing better models to be built with combined data sets. LIBS and Raman data present different challenges for CT. Quantitative geochemical analyses by LIBS spectroscopy are limited by lack of consistency among repeated laser shots and across instruments. Many different factors affect the presence/absence of emission lines and their intensities, such as laser power/plasma temperature, angle of incidence, detector sensitivity/resolution. To overcome these, models in which disparate datasets are projected into a joint low-dimensional subspace where all data can be aligned before quantitative analysis, such as Correlation Analysis for Domain Adaptation (CADA), have proven very effective. They require some overlap between the populations of spectra to be aligned. For example, prediction of SiO2 on 80 samples from two different LIBS labs show errors of ±16-29 wt.% when the training and test sets have no overlap, and ±4.94 wt% SiO2 when CADA is used. Uncorrected Earth-Mars spectral differences are likely to cause errors with the same order of magnitude. As with other types of reflectance spectroscopy, Raman data are plagued by differences among single crystal/powder samples and laser wavelength that affect peak intensities, and by spectral offsets from instruments with varying resolution and wavenumber alignment schemes. These problems persist even within the archetypal RRUFF database. Pre-processing transformation functions such as optimized baseline removal

  15. Raman tweezers spectroscopy of live, single red and white blood cells.

    Directory of Open Access Journals (Sweden)

    Aseefhali Bankapur

    Full Text Available An optical trap has been combined with a Raman spectrometer to make high-resolution measurements of Raman spectra of optically-immobilized, single, live red (RBC and white blood cells (WBC under physiological conditions. Tightly-focused, near infrared wavelength light (1064 nm is utilized for trapping of single cells and 785 nm light is used for Raman excitation at low levels of incident power (few mW. Raman spectra of RBC recorded using this high-sensitivity, dual-wavelength apparatus has enabled identification of several additional lines; the hitherto-unreported lines originate purely from hemoglobin molecules. Raman spectra of single granulocytes and lymphocytes are interpreted on the basis of standard protein and nucleic acid vibrational spectroscopy data. The richness of the measured spectrum illustrates that Raman studies of live cells in suspension are more informative than conventional micro-Raman studies where the cells are chemically bound to a glass cover slip.

  16. Nanoscale Stress Field Evaluation with Shallow Trench Isolation Structure Assessed by Cathodoluminescence Spectroscopy, Raman Spectroscopy, and Finite Element Method Analyses (United States)

    Kodera, Masako; Iguchi, Tadashi; Tsuchiya, Norihiko; Tamura, Mizuki; Kakinuma, Shigeru; Naka, Nobuyuki; Kashiwagi, Shinsuke


    Stress engineering related to the LSI process is required. With shallow trench isolation (STI) structures, a high stress field causes a variation in electrical characteristics. Although stress fields in a Si substrate can be detected by Raman spectroscopy, no effective technique has been reported for the measurement of nanoscale stress fields in a dielectric material used for STI filling. Recently, we have reported that “cathodoluminescence (CL) spectroscopy” enables us to detect nanometer-scale stress fields in LSI structures. In this study, we performed the first estimation of the stress fields with a STI structure by CL and Raman spectroscopy, as well as finite element method (FEM) calculation. We were able to repeatedly acquire clear stress distributions by CL and Raman spectroscopy. Moreover, CL, Raman, and FEM results showed excellent agreement with one another, revealing that a large variation in stresses along the AA/STI boundary was induced by the intrinsic tensile stress of the SiO2 film.

  17. 1064nm FT-Raman spectroscopy for investigations of plant cell walls and other biomass materials (United States)

    Umesh P. Agarwal


    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...

  18. Fast single-photon avalanche diode arrays for laser Raman spectroscopy

    NARCIS (Netherlands)

    Blacksberg, J.; Maruyama, Y.; Charbon, E.; Rossman, G.R.


    We incorporate newly developed solid-state detector technology into time-resolved laser Raman spectroscopy, demonstrating the ability to distinguish spectra from Raman and fluorescence processes. As a proof of concept, we show fluorescence rejection on highly fluorescent mineral samples willemite

  19. Determination of ethylenic residues in wood and TMP of spruce by FT-Raman spectroscopy (United States)

    Umesh P. Agarwal; Sally A. Ralph


    A method based on FT-Raman spectroscopy is proposed for determining in situ concentrations of ethylenic residues in softwood lignin. Raman contributions at 1133 and 1654 cm-1, representing coniferaldehyde and coniferyl alcohol structures, respectively, were used in quantifying these units in spruce wood with subsequent conversion to concentrations in lignin. For...

  20. Cellulose I crystallinity determination using FT-Raman spectroscopy : univariate and multivariate methods (United States)

    Umesh P. Agarwal; Richard S. Reiner; Sally A. Ralph


    Two new methods based on FT–Raman spectroscopy, one simple, based on band intensity ratio, and the other using a partial least squares (PLS) regression model, are proposed to determine cellulose I crystallinity. In the simple method, crystallinity in cellulose I samples was determined based on univariate regression that was first developed using the Raman band...

  1. Following lipids in the food chain: determination of the iodine value using Raman micro-spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Samek, Ota; Zemánek, Pavel; Bernatová, Silvie; Pilát, Zdeněk; Telle, H.H.


    Roč. 24, č. 3 (2012), s. 18-21 ISSN 0966-0941 R&D Projects: GA ČR GAP205/11/1687; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : Raman micro-spectroscopy * Raman laser excitation * lipids Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. “Self-absorption” phenomenon in near-infrared Fourier transform Raman spectroscopy of cellulosic and lignocellulosic materials (United States)

    Umesh P. Agarwal; Nancy Kawai


    While cellulosic and lignocellulosic materials have been studied using conventional Raman spectroscopy, availability of near-infrared (NIR) Fourier transform (FT) Raman instrumentation has made studying these materials much more convenient. This is especially true because the problem of laser-induced fluorescence can be avoided or minimized in FT- Raman (NIR Raman)...

  3. Comparison of fluorescence rejection methods of baseline correction and shifted excitation Raman difference spectroscopy (United States)

    Cai, Zhijian; Zou, Wenlong; Wu, Jianhong


    Raman spectroscopy has been extensively used in biochemical tests, explosive detection, food additive and environmental pollutants. However, fluorescence disturbance brings a big trouble to the applications of portable Raman spectrometer. Currently, baseline correction and shifted-excitation Raman difference spectroscopy (SERDS) methods are the most prevailing fluorescence suppressing methods. In this paper, we compared the performances of baseline correction and SERDS methods, experimentally and simulatively. Through the comparison, it demonstrates that the baseline correction can get acceptable fluorescence-removed Raman spectrum if the original Raman signal has good signal-to-noise ratio, but it cannot recover the small Raman signals out of large noise background. By using SERDS method, the Raman signals, even very weak compared to fluorescence intensity and noise level, can be clearly extracted, and the fluorescence background can be completely rejected. The Raman spectrum recovered by SERDS has good signal to noise ratio. It's proved that baseline correction is more suitable for large bench-top Raman system with better quality or signal-to-noise ratio, while the SERDS method is more suitable for noisy devices, especially the portable Raman spectrometers.

  4. Probing the Interaction of Ionic Liquids with CO2: A Raman Spectroscopy and Ab Initio Study

    National Research Council Canada - National Science Library

    Eucker, IV, William


    ...) with selected ionic liquids (ILs). Raman spectroscopy and first principle quantum mechanical calculations were performed on selected IL solvents in contact with CO2 in the effort to discover how the solvents interact with the gas. ILs are salts...

  5. Covalent Reactions on Chemical Vapor Deposition Grown Graphene Studied by Surface-Enhanced Raman Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kovaříček, Petr; Bastl, Zdeněk; Valeš, Václav; Kalbáč, Martin


    Roč. 22, č. 15 (2016), s. 5404-5408 ISSN 1521-3765 R&D Projects: GA MŠk LL1301 Institutional support: RVO:61388955 Keywords : graphene * nanomaterials * Raman spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry

  6. A classification model for non-alcoholic steatohepatitis (NASH) using confocal Raman micro-spectroscopy (United States)

    Yan, Jie; Yu, Yang; Kang, Jeon Woong; Tam, Zhi Yang; Xu, Shuoyu; Fong, Eliza Li Shan; Singh, Surya Pratap; Song, Ziwei; Tucker Kellogg, Lisa; So, Peter; Yu, Hanry


    We combined Raman micro-spectroscopy and machine learning techniques to develop a classification model based on a well-established non-alcoholic steatohepatitis (NASH) mouse model, using spectrum pre-processing, biochemical component analysis (BCA) and logistic regression.

  7. Ultrastable and Compact Deep UV Laser Source for Raman Spectroscopy, Phase II (United States)

    National Aeronautics and Space Administration — Deep-ultraviolet (DUV) Raman spectroscopy is a powerful method to isolate and extract the unique signatures of numerous chemical bonds present within complex...

  8. Ultrastable and Compact Deep UV Laser Source for Raman Spectroscopy, Phase I (United States)

    National Aeronautics and Space Administration — Deep-ultraviolet (UV) Raman spectroscopy is a powerful method to collect chemically specific information about complex samples because deep-UV (?? < 250 nm)...

  9. In situ TEM Raman spectroscopy and laser-based materials modification

    Energy Technology Data Exchange (ETDEWEB)

    Allen, F.I., E-mail: [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Kim, E. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Andresen, N.C. [Engineering Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Grigoropoulos, C.P. [Department of Mechanical Engineering, University of California, Berkeley, CA 94720 (United States); Minor, A.M., E-mail: [Department of Materials Science and Engineering, University of California, Berkeley, CA 94720 (United States); National Center for Electron Microscopy, Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)


    We present a modular assembly that enables both in situ Raman spectroscopy and laser-based materials processing to be performed in a transmission electron microscope. The system comprises a lensed Raman probe mounted inside the microscope column in the specimen plane and a custom specimen holder with a vacuum feedthrough for a tapered optical fiber. The Raman probe incorporates both excitation and collection optics, and localized laser processing is performed using pulsed laser light delivered to the specimen via the tapered optical fiber. Precise positioning of the fiber is achieved using a nanomanipulation stage in combination with simultaneous electron-beam imaging of the tip-to-sample distance. Materials modification is monitored in real time by transmission electron microscopy. First results obtained using the assembly are presented for in situ pulsed laser ablation of MoS{sub 2} combined with Raman spectroscopy, complimented by electron-beam diffraction and electron energy-loss spectroscopy. - Highlights: • Raman spectroscopy and laser-based materials processing in a TEM are demonstrated. • A lensed Raman probe is mounted in the sample chamber for close approach. • Localized laser processing is achieved using a tapered optical fiber. • Raman spectroscopy and pulsed laser ablation of MoS{sub 2} are performed in situ.

  10. Measuring depth profiles of residual stress with Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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


    Knowledge of the variation of residual stress is a very important factor in understanding the properties of machined surfaces. The nature of the residual stress can determine a part`s susceptibility to wear deformation, and cracking. Raman spectroscopy is known to be a very useful technique for measuring residual stress in many materials. These measurements are routinely made with a lateral resolution of 1{mu}m and an accuracy of 0.1 kbar. The variation of stress with depth; however, has not received much attention in the past. A novel technique has been developed that allows quantitative measurement of the variation of the residual stress with depth with an accuracy of 10nm in the z direction. Qualitative techniques for determining whether the stress is varying with depth are presented. It is also demonstrated that when the stress is changing over the volume sampled, errors can be introduced if the variation of the stress with depth is ignored. Computer aided data analysis is used to determine the depth dependence of the residual stress.

  11. Raman spectroscopy of human vitreous collagen in diabetic retinopathy (United States)

    Sebag, Jerry; Nie, Shuming; Reiser, Karen M.; Yu, Nai-Teng


    In diabetes nonenzymatic glycation alters collagen throughout the body resulting in the histopathology that underlies diabetic disease in several organs. In the eye such changes in vitreous collagen could contribute to vitreous degeneration and the progression of proliferative diabetic retinopathy. Previous studies have demonstrated early glycation and advanced endproducts in the vitreous of humans with proliferative diabetic retinopathy. Near-infrared Fourier-transform Raman spectroscopy was performed on vitreous obtained at surgery from diabetic patients and from non-diabetic control subjects. The findings were compared to measurements obtained in untreated and glycated (in vitro) rat-tail tendon collagen. The results demonstrated substantial changes in diabetic vitreous collagen resulting from glycation, most likely advanced glycation endproducts. This approach appears to be useful as a means of characterizing the molecular changes induced by diabetes. Furthermore, this technique could be developed as a way of quantifying these changes in vivo in several tissues, so as to gauge the severity of non-enzymatic glycation and monitor the response to therapy.

  12. A pseudo-Voigt component model for high-resolution recovery of constituent spectra in Raman spectroscopy

    DEFF Research Database (Denmark)

    Alstrøm, Tommy Sonne; Schmidt, Mikkel Nørgaard; Rindzevicius, Tomas


    Raman spectroscopy is a well-known analytical technique for identifying and analyzing chemical species. Since Raman scattering is a weak effect, surface-enhanced Raman spectroscopy (SERS) is often employed to amplify the signal. SERS signal surface mapping is a common method for detecting trace a...

  13. Surface enhanced Raman spectroscopy: A review of recent applications in forensic science. (United States)

    Fikiet, Marisia A; Khandasammy, Shelby R; Mistek, Ewelina; Ahmed, Yasmine; Halámková, Lenka; Bueno, Justin; Lednev, Igor K


    Surface enhanced Raman spectroscopy has many advantages over its parent technique of Raman spectroscopy. Some of these advantages such as increased sensitivity and selectivity and therefore the possibility of small sample sizes and detection of small concentrations are invaluable in the field of forensics. A variety of new SERS surfaces and novel approaches are presented here on a wide range of forensically relevant topics. Copyright © 2018 Elsevier B.V. All rights reserved.

  14. INSTRUMENTS AND METHODS OF INVESTIGATION: New nonlinear laser effects in α-quartz: generation of a two-octave Stokes and anti-Stokes comb and cascaded lasing in the spectral range of the second and third harmonics (United States)

    Kaminskii, A. A.; Bohatý, L.; Becker, P.; Eichler, H. J.; Rhee, H.


    Crystals that are simultaneously χ(2)- and χ(3)-active offer a wide range of possibilities for the generation of new coherent wavelengths of light. Frequency conversion processes such as stimulated Raman scattering, second and third harmonic generation, or parametric sum and difference frequency mixing can be combined effectively in the same noncentrosymmetric crystal in cascaded χ(3) χ(2) lasing processes. We present several new manifestations of these effects under picosecond laser excitation in α-quartz (SiO2), the oldest nonlinear-laser crystal. Among them are 45 Stokes and anti-Stokes wavelength comb generation of more than two octaves (from 0.3692 μm to 1.5142 μm) and self-conversion of Raman-generation frequencies into the wavelength region of the second and third harmonics of one-micron pumping via many-step cascaded χ(3) χ(2) processes.

  15. Application of Raman Spectroscopy and Infrared Spectroscopy in the Identification of Breast Cancer. (United States)

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


    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

  16. [Rapid identification of potato cultivars using NIR-excited fluorescence and Raman spectroscopy]. (United States)

    Dai, Fen; Bergholt, Mads Sylvest; Benjamin, Arnold Julian Vinoj; Hong, Tian-Sheng; Zhiwei, Huang


    Potato is one of the most important food in the world. Rapid and noninvasive identification of potato cultivars plays a important role in the better use of varieties. In this study, The identification ability of optical spectroscopy techniques, including near-infrared (NIR) Raman spectroscopy and NIR fluorescence spectroscopy, for invasive detection of potato cultivars was evaluated. A rapid NIR Raman spectroscopy system was applied to measure the composite Raman and NIR fluorescence spectroscopy of 3 different species of potatoes (98 samples in total) under 785 nm laser light excitation. Then pure Raman and NIR fluorescence spectroscopy were abstracted from the composite spectroscopy, respectively. At last, the partial least squares-discriminant analysis (PLS-DA) was utilized to analyze and classify Raman spectra of 3 different types of potatoes. All the samples were divided into two sets at random: the calibration set (74samples) and prediction set (24 samples), the model was validated using a leave-one-out, cross-validation method. The results showed that both the NIR-excited fluorescence spectra and pure Raman spectra could be used to identify three cultivars of potatoes. The fluorescence spectrum could distinguish the Favorita variety well (sensitivity: 1, specificity: 0.86 and accuracy: 0.92), but the result for Diamant (sensitivity: 0.75, specificity: 0.75 and accuracy: 0. 75) and Granola (sensitivity: 0.16, specificity: 0.89 and accuracy: 0.71) cultivars identification were a bit poorer. We demonstrated that Raman spectroscopy uncovered the main biochemical compositions contained in potato species, and provided a better classification sensitivity, specificity and accuracy (sensitivity: 1, specificity: 1 and accuracy: 1 for all 3 potato cultivars identification) among the three types of potatoes as compared to fluorescence spectroscopy.

  17. A Raman Flow Cytometer: An Innovative Microfluidic Approach for Continuous Label-Free Analysis of Cells via Raman Spectroscopy

    KAUST Repository

    De Grazia, Antonio


    In this work a Raman flow cytometer is presented. It is a whole new microfluidic device that takes advantage of basic principles of Raman spectroscopy and fluorescent flow cytometry mixed together in a system of particularly shaped channels. These are indeed composed by specific shape and sizes – thanks to which cells can flow one-by-one – and a trap by means of which cells are trapped in order to perform Raman analysis on single ones in a constant and passive way. In this sense the microfluidic device promotes a fast method to look for single cells in a whole multicellular sample. It is a label-free analysis and this means that, on the contrary of what happens with fluorescent flow cytometry, the sample does not need to undergo any particular time-consuming pretreatment before being analyzed. Moreover it gives a complete information about the biochemical content of the sample thanks to the involvement of Raman spectroscopy as method of analysis. Many thought about a device like this, but eventually it is the first one being designed, fabricated and tested. The materials involved in the production of the Raman flow cytometer are chosen wisely. In particular the chip – the most important component of the device – is multilayered, being composed by a slide of calcium fluoride (which gives a negligible signal in Raman analyses), a photosensitive resist containing a pattern with channels and another slide of calcium fluoride in order for the channels to be sealed on both sides. The chip is, in turn, connected to gaskets and external frames. Several fabrication processes are followed to ultimately get the complete Raman flow cytometer and experiments on red blood cells demonstrate its validity in this field.

  18. Application of micro Raman spectroscopy to industrial FC membranes

    International Nuclear Information System (INIS)

    Chikvaidze, G; Gabrusenoks, J; Kleperis, J; Vaivars, G


    Raman spectra of as-received and protonated membranes (Nafion NRE-212, Fumapem F-14100 and Fumasep FAA) were measured with He-Cd and Ar laser. For the first time the Raman and IR spectra are reported of Fumasep membranes. Most of peaks in vibration spectra active in Raman and IR of membranes are interpreted with C-F, C-S, C-O-C, SO 3 , C-C bonds. The vibration region connected with protons and H-O bond in both types of membranes is found in Raman and IR spectra

  19. Infrared and Raman spectroscopy: principles and spectral interpretation

    National Research Council Canada - National Science Library

    Larkin, Peter


    .... The book reviews basic principles, instrumentation, sampling methods, quantitative analysis, origin of group frequencies and qualitative interpretation using generalized Infrared (IR) and Raman spectra...

  20. Using Raman Spectroscopy and Surface-Enhanced Raman Scattering to Identify Colorants in Art: An Experiment for an Upper-Division Chemistry Laboratory (United States)

    Mayhew, Hannah E.; Frano, Kristen A.; Svoboda, Shelley A.; Wustholz, Kristin L.


    Surface-enhanced Raman scattering (SERS) studies of art represent an attractive way to introduce undergraduate students to concepts in nanoscience, vibrational spectroscopy, and instrumental analysis. Here, we present an undergraduate analytical or physical chemistry laboratory wherein a combination of normal Raman and SERS spectroscopy is used to…

  1. Characterization and differentiation of normal and abnormal spermatozoa via micro-Raman spectroscopy (United States)

    Huang, Z. F.; Chen, X. W.; Chen, G. N.; Chen, J. H.; Wang, J.; Lin, J. Q.; Zeng, H. S.; Chen, R.


    Growth in the percentage of spermatozoa with aberrant sperm head morphologies has been correlated with a rise in male infertility. In our study, micro-Raman spectroscopy using a new substrate was utilized to characterize and differentiate the morphologically normal and abnormal human sperm cells based on their different biochemical components by showing their different specific Raman spectra. A detailed classification based on the PCA-LDA method was performed showing a diagnostic sensitivity of 76% and specificity of 91%, with 80% classification accuracy. Our results suggest that micro-Raman spectroscopy can serve as a reliable and non-invasive tool for detection and differentiation of human spermatozoa.

  2. New Applications of Portable Raman Spectroscopy in Agri-Bio-Photonics (United States)

    Voronine, Dmitri; Scully, Rob; Sanders, Virgil


    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.

  3. Study of CVD diamond layers with amorphous carbon admixture by Raman scattering spectroscopy

    Directory of Open Access Journals (Sweden)

    Dychalska Anna


    Full Text Available Raman spectroscopy is a most often used standard technique for characterization of different carbon materials. In this work we present the Raman spectra of polycrystalline diamond layers of different quality, synthesized by Hot Filament Chemical Vapor Deposition method (HF CVD. We show how to use Raman spectroscopy for the analysis of the Raman bands to determine the structure of diamond films as well as the structure of amorphous carbon admixture. Raman spectroscopy has become an important technique for the analysis of CVD diamond films. The first-order diamond Raman peak at ca. 1332 cm−1 is an unambiguous evidence for the presence of diamond phase in the deposited layer. However, the existence of non-diamond carbon components in a CVD diamond layer produces several overlapping peaks in the same wavenumber region as the first order diamond peak. The intensities, wavenumber, full width at half maximum (FWHM of these bands are dependent on quality of diamond layer which is dependent on the deposition conditions. The aim of the present work is to relate the features of diamond Raman spectra to the features of Raman spectra of non-diamond phase admixture and occurrence of other carbon structures in the obtained diamond thin films.

  4. Micro Structural Analysis of In2S3 Thin Films by Raman Spectroscopy (United States)

    Izadneshana, H.; Gremenok, V. F.


    In2S3 thin films with different thicknesses were deposited on glass substrates using the thermal evaporation method. The as-deposited films were annealed in vacuum at 330 and 400°C for 30 and 60 min. We used Raman spectroscopy and X-ray diffraction to evaluate the effect of thermal treatment on the film structures. Raman active modes that can be classified as 9A1 and 14E modes have been observed in the Raman spectra of the In2S3 thin films. Variations in the Raman shift and bandwidth of different In2S3 thin films reveal the influence of the annealing effect. Results of Raman spectroscopy and XRD show that the annealing effect changes the crystallization phase from tetragonal to cubic at high temperatures.

  5. Quantitative determination of the human breast milk macronutrients by near-infrared Raman spectroscopy (United States)

    Motta, Edlene d. C. M.; Zângaro, Renato A.; Silveira, Landulfo, Jr.


    This work proposes the evaluation of the macronutrient constitution of human breast milk based on the spectral information provided by near-infrared Raman spectroscopy. Human breast milk (5 mL) from a subject was collected during the first two weeks of breastfeeding and stocked in -20°C freezer. Raman spectra were measured using a Raman spectrometer (830 nm excitation) coupled to a fiber based Raman probe. Spectra of human milk were dominated by bands of proteins, lipids and carbohydrates in the 600-1800 cm-1 spectral region. Raman spectroscopy revealed differences in the biochemical constitution of human milk depending on the time of breastfeeding startup. This technique could be employed to develop a classification routine for the milk in Human Milk Banking (HMB) depending on the nutritional facts.

  6. Surface-Enhanced Raman Spectroscopy Based Quantitative Bioassay on Aptamer-Functionalized Nanopillars Using Large-Area Raman Mapping

    DEFF Research Database (Denmark)

    Yang, Jaeyoung; Palla, Mirko; Bosco, Filippo


    Surface-enhanced Raman spectroscopy (SERS) has been used in a variety of biological applications due to its high sensitivity and specificity. Here, we report a SERS-based biosensing approach for quantitative detection of biomolecules. A SERS substrate bearing gold-decorated silicon nanopillars......-to-spot variation in conventional SERS quantification. Furthermore, we have developed an analytical model capable of predicting experimental intensity distributions on the substrates for reliable quantification of biomolecules. Lastly, we have calculated the minimum needed area of Raman mapping for efficient...

  7. Insights into Protein Structure and Dynamics by Ultraviolet and Visible Resonance Raman Spectroscopy. (United States)

    López-Peña, Ignacio; Leigh, Brian S; Schlamadinger, Diana E; Kim, Judy E


    Raman spectroscopy is a form of vibrational spectroscopy based on inelastic scattering of light. In resonance Raman spectroscopy, the wavelength of the incident light falls within an absorption band of a chromophore, and this overlap of excitation and absorption energy greatly enhances the Raman scattering efficiency of the absorbing species. The ability to probe vibrational spectra of select chromophores within a complex mixture of molecules makes resonance Raman spectroscopy an excellent tool for studies of biomolecules. In this Current Topic, we discuss the type of molecular insights obtained from steady-state and time-resolved resonance Raman studies of a prototypical photoactive protein, rhodopsin. We also review recent efforts in ultraviolet resonance Raman investigations of soluble and membrane-associated biomolecules, including integral membrane proteins and antimicrobial peptides. These examples illustrate that resonance Raman is a sensitive, selective, and practical method for studying the structures of biological molecules, and the molecular bonding, geometry, and environments of protein cofactors, the backbone, and side chains.

  8. Intensity-carrying modes in Raman and Raman optical activity spectroscopy. (United States)

    Luber, Sandra; Reiher, Markus


    We describe a quantum-chemical approach for the determination of modes with maximum Raman and Raman optical activity (ROA) intensity by maximizing the intensities with respect to the Raman and Raman optical activity intensity, respectively, which is shown to lead to eigenvalue equations. The intensity-carrying modes are in general hypothetical modes and do not directly correspond to a certain normal mode in the spectrum. However, they provide information about those molecular distortions leading to intense bands in the spectrum. Modes with maximum Raman intensity are presented for propane-1,3-dione, propane-1,3-dionate, and Lambda-tris(propane-1,3-dionato)cobalt(III). Moreover, the mode with highest ROA intensity is examined for this chiral cobalt complex and also for the (chiral) amino acid L-tryptophan. The Raman and ROA high-intensity modes are an optimal starting guess for intensity-tracking calculations, in which selectively normal modes with high Raman or ROA intensity are converged. We present the first Raman and ROA intensity-tracking calculations. These reveal a high potential for large molecules, for which the selective calculation of normal modes with high intensity is desirable in view of the large computational effort required for the calculation of Raman and ROA polarizability property tensors.

  9. Integrated fingerprint and high wavenumber confocal Raman spectroscopy for in vivo diagnosis of cervical precancer (United States)

    Duraipandian, Shiyamala; Zheng, Wei; Ng, Joseph; Low, Jeffrey J. H.; Ilancheran, A.; Huang, Zhiwei


    Raman spectroscopy is a vibrational spectroscopic technique capable of optically probing the compositional, conformational, and structural changes in the tissue associated with disease progression. The main goal of this work is to develop an integrated fingerprint (FP) and high wavenumber (HW) in vivo confocal Raman spectroscopy for simultaneous FP/HW tissue Raman spectral measurements. This work further explores the potential of integrated FP/HW Raman spectroscopy developed as a diagnostic tool for in vivo detection of cervical precancer. A total of 473 in vivo integrated FP/HW Raman spectra (340 normal and 133 precancer) were acquired from 35 patients within 1 s during clinical colposcopy. The major tissue Raman peaks are noticed around 854, 937, 1001, 1095, 1253, 1313, 1445, 1654, 2946 and 3400 cm-1, related to the molecular changes (e.g., proteins, lipids, glycogen, nucleic acids, water, etc.) that accompany the dysplastic transformation of tissue. The FP (800 - 1800 cm-1), HW (2800 - 3800 cm-1) and the integrated FP/HW Raman spectra were analyzed using partial least squares-discriminant analysis (PLS-DA) together with the leave-one patient-out, cross-validation. The developed PLS-DA classification models and receiver operating characteristics (ROC) curves for the FP, HW and integrated FP/HW spectroscopy further discloses that the performance of integrated FP/HW Raman spectroscopy is superior to that of all others in discriminating the dysplastic cervix. The results of this work indicate that the co-contributions of underlying rich biochemical information revealed by the complementary spectral modalities (FP and HW Raman) can improve the in vivo early diagnosis of cervical precancer at clinical colposcopy

  10. Precision of Raman Spectroscopy Measurements in Detection of Microcalcifications in Breast Needle Biopsies (United States)

    Saha, Anushree; Barman, Ishan; Dingari, Narahara Chari; Galindo, Luis H.; Sattar, Abdus; Liu, Wendy; Plecha, Donna; Klein, Nina; Dasari, Ramachandra Rao; Fitzmaurice, Maryann


    Microcalcifications are an early mammographic sign of breast cancer and a target for stereotactic breast needle biopsy. We developed Raman spectroscopy decision algorithms to detect breast microcalcifications, based on fit coefficients (FC) derived by modeling tissue Raman spectra as a linear combination of the Raman spectra of 9 chemical and morphologic components of breast tissue. However, little or no information is available on the precision of such measurements and its effect on the ability of Raman spectroscopy to make predictions for breast microcalcification detection. Here we report the precision, that is, the closeness of agreement between replicate Raman spectral measurements - and the model FC derived from them - obtained ex vivo from fresh breast biopsies from patients undergoing stereotactic breast needle biopsy, using a compact clinical Raman system. The coefficients of variation of the model FC averaged 0.03 for normal breast tissue sites, 0.12 for breast lesions without and 0.22 for breast lesions with microcalcifications. Imprecision in the FC resulted in diagnostic discordance among replicates only for line-sitters, that is, tissue sites with FC values near the decision line or plane. The source of this imprecision and their implications for the use of Raman spectroscopy for guidance of stereotactic breast biopsies for microcalcifications are also discussed. In summary, we conclude that the precision of Raman spectroscopy measurements in breast tissue obtained using our compact clinical system is more than adequate to make accurate and repeatable predictions of microcalcifications in breast tissue using decision algorithms based on model FC. This provides strong evidence of the potential of Raman spectroscopy guidance of stereotactic breast needle biopsies for microcalcifications. PMID:22746329

  11. Shot-Noise Limited Time-Encoded Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Sebastian Karpf


    Full Text Available Raman scattering, an inelastic scattering mechanism, provides information about molecular excitation energies and can be used to identify chemical compounds. Albeit being a powerful analysis tool, especially for label-free biomedical imaging with molecular contrast, it suffers from inherently low signal levels. This practical limitation can be overcome by nonlinear enhancement techniques like stimulated Raman scattering (SRS. In SRS, an additional light source stimulates the Raman scattering process. This can lead to orders of magnitude increase in signal levels and hence faster acquisition in biomedical imaging. However, achieving a broad spectral coverage in SRS is technically challenging and the signal is no longer background-free, as either stimulated Raman gain (SRG or loss (SRL is measured, turning a sensitivity limit into a dynamic range limit. Thus, the signal has to be isolated from the laser background light, requiring elaborate methods for minimizing detection noise. Here, we analyze the detection sensitivity of a shot-noise limited broadband stimulated time-encoded Raman (TICO-Raman system in detail. In time-encoded Raman, a wavelength-swept Fourier domain mode locking (FDML laser covers a broad range of Raman transition energies while allowing a dual-balanced detection for lowering the detection noise to the fundamental shot-noise limit.

  12. In and ex vivo breast disease study by Raman spectroscopy

    DEFF Research Database (Denmark)

    Raniero, L.; Canevari, R. A.; Ramalho, L. N. Z.


    In this work, Raman spectra in the 900-1,800 cm(-1) wavenumber region of in vivo and ex vivo breast tissues of both healthy mice (normal) and mice with induced mammary gland tumors (abnormal) were measured. In the case of the in vivo tissues, the Raman spectra were collected for both transcutaneo...

  13. Raman spectroscopy of graphene on different substrates and ...

    Indian Academy of Sciences (India)

    We show the evolution of Raman spectra with a number of graphene layers on different substrates, SiO2/Si and conducting indium tin oxide (ITO) plate. The mode peak position and the intensity ratio of and 2 bands depend on the preparation of sample for the same number of graphene layers. The 2 Raman band ...

  14. Surface-enhanced Raman spectroscopy of DNA bases

    NARCIS (Netherlands)

    Otto, Cornelis; van den Tweel, T.J.J.; de Mul, F.F.M.; Greve, Jan


    A Raman microprobe has been used to measure the surface-enhanced Raman spectra of adenine, guanine, cytosine and thymine. Comparison of the SERS spectrum with solution spectra shows that some line positions are not influenced by the adsorption process while others show large shifts. In the SERS

  15. Single-cell Raman spectroscopy of irradiated tumour cells (United States)

    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

  16. Phenotypic Profiling of Antibiotic Response Signatures in Escherichia coli Using Raman Spectroscopy (United States)

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


    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

  17. Applications of the Raman spectroscopy in the materials characterization

    International Nuclear Information System (INIS)

    Jimenez S, S.; Escobar A, L.; Camacho L, M. A.


    The study field of the science and technology of surfaces and materials have been of primordial importance in the last years due to the impact that they have the knowledge that it generates in diverse areas. For this reason, the Mexican Society of Science and Technology of Surfaces and Materials has focused a good part of their investigation activities toward the materials science and technology development. Inside the investigation fields carried out by members of this Society, are the following: semiconductors, thin films, hard coatings, deposit techniques, plasmas, biomaterials, Ab-initio calculations, characterization techniques, photo-thermal properties, solar cells, nano science, magnetism, superconductivity and related topics. Among the techniques used for this purpose is the Raman Spectroscopy (Rs), which has demonstrated to be a powerful and versatile tool in the materials study. In the last three congresses that the Society has organized, an average of 42 works related with this topic have been presented, what gave the rule to prepare this book whose objective is on one hand diffusing part of the works that carry out different groups integrated with members of the Society that use the Rs like an important tool in its investigation work. A second objective is that it can serve like support to the students that begin to be involved, or that they are already involved, in topics where the Rs can have a decisive paper in the development of its projects. It is also expected that some of the topics included in the book are of utility for professors and researches that already uses the Rs, or that it can be of help for those who are beginning in this technique as alternative or like complementary analysis tool. (Author)

  18. Synthesizing and Characterizing Graphene via Raman Spectroscopy: An Upper-Level Undergraduate Experiment That Exposes Students to Raman Spectroscopy and a 2D Nanomaterial (United States)

    Parobek, David; Shenoy, Ganesh; Zhou, Feng; Peng, Zhenbo; Ward, Michelle; Liu, Haitao


    In this upper-level undergraduate experiment, students utilize micro-Raman spectroscopy to characterize graphene prepared by mechanical exfoliation and chemical vapor deposition (CVD). The mechanically exfoliated samples are prepared by the students while CVD graphene can be purchased or obtained through outside sources. Owing to the intense Raman…

  19. Electromagnetic theories of surface-enhanced Raman spectroscopy. (United States)

    Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin


    Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

  20. Raman Spectra of High-κ Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide

    Directory of Open Access Journals (Sweden)

    P. Borowicz


    Full Text Available Three samples with dielectric layers from high-κ dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high-κ dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above, the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide.

  1. Anti-Stokes scattering and Stokes scattering of stimulated Brillouin scattering cascade in high-intensity laser-plasma interaction (United States)

    Feng, Q. S.; Liu, Z. J.; Zheng, C. Y.; Xiao, C. Z.; Wang, Q.; Zhang, H. C.; Cao, L. H.; He, X. T.


    Anti-Stokes scattering and Stokes scattering in stimulated Brillouin scattering (SBS) cascades have been researched using the Vlasov-Maxwell simulation. In high-intensity laser-plasma interactions, stimulated anti-Stokes Brillouin scattering (SABS) will occur after second stage SBS rescattering. The mechanism of SABS has been put forward to explain this phenomenon. In the early phase of SBS evolution, only first stage SBS appears and total SBS reflectivity comes from first stage SBS. However, when high-stage SBS and SABS occur, SBS reflectivity will display burst behavior and the total reflectivity comes from the SBS cascade and SABS superimposition. The SABS will compete with the SBS rescattering to determine the total SBS reflectivity. Thus, SBS rescattering including SABS is an important saturation mechanism of SBS and should be taken into account in high-intensity laser-plasma interaction.

  2. Integration of Correlative Raman microscopy in a dual beam FIB-SEM J. of Raman Spectroscopy

    NARCIS (Netherlands)

    Timmermans, Frank Jan; Liszka, B.; Lenferink, Aufrid T.M.; van Wolferen, Hendricus A.G.M.; Otto, Cornelis


    We present an integrated confocal Raman microscope in a focused ion beam scanning electron microscope (FIB SEM). The integrated system enables correlative Raman and electron microscopic analysis combined with focused ion beam sample modification on the same sample location. This provides new

  3. Wave mixing spectroscopy

    International Nuclear Information System (INIS)

    Smith, R.W.


    Several new aspects of nonlinear or wave mixing spectroscopy were investigated utilizing the polarization properties of the nonlinear output field and the dependence of this field upon the occurrence of multiple resonances in the nonlinear susceptibility. First, it is shown theoretically that polarization-sensitive detection may be used to either eliminate or controllably reduce the nonresonant background in coherent anti-Stokes Raman spectroscopy, allowing weaker Raman resonances to be studied. The features of multi-resonant four-wave mixing are examined in the case of an inhomogeneously broadened medium. It is found that the linewidth of the nonlinear output narrows considerably (approaching the homogeneous width) when the quantum mechanical expressions for the doubly- and triply-resonant susceptibilities are averaged over a Doppler or strain broadened profile. Experimental studies of nonlinear processes in Pr +3 :LaF 3 verify this linewidth narrowing, but indicate that this strain broadened system cannot be treated with a single broadening parameter as in the case of Doppler broadening in a gas. Several susceptibilities are measured from which are deduced dipole matrix elements and Raman polarizabilities related to the 3 H 4 , 3 H 6 , and 3 P 0 levels of the praseodymium ions

  4. In situ monitoring of cocrystals in formulation development using low-frequency Raman spectroscopy. (United States)

    Otaki, Takashi; Tanabe, Yuta; Kojima, Takashi; Miura, Masaru; Ikeda, Yukihiro; Koide, Tatsuo; Fukami, Toshiro


    In recent years, to guarantee a quality-by-design approach to the development of pharmaceutical products, it is important to identify properties of raw materials and excipients in order to determine critical process parameters and critical quality attributes. Feedback obtained from real-time analyses using various process analytical technology (PAT) tools has been actively investigated. In this study, in situ monitoring using low-frequency (LF) Raman spectroscopy (10-200 cm -1 ), which may have higher discriminative ability among polymorphs than near-infrared spectroscopy and conventional Raman spectroscopy (200-1800 cm -1 ), was investigated as a possible application to PAT. This is because LF-Raman spectroscopy obtains information about intermolecular and/or lattice vibrations in the solid state. The monitoring results obtained from Furosemide/Nicotinamide cocrystal indicate that LF-Raman spectroscopy is applicable to in situ monitoring of suspension and fluidized bed granulation processes, and is an effective technique as a PAT tool to detect the conversion risk of cocrystals. LF-Raman spectroscopy is also used as a PAT tool to monitor reactions, crystallizations, and manufacturing processes of drug substances and products. In addition, a sequence of conversion behaviors of Furosemide/Nicotinamide cocrystals was determined by performing in situ monitoring for the first time. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy

    NARCIS (Netherlands)

    Sovago, M.; Buis, E.-J.; Sandtke, M.


    We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP

  6. A novel non-imaging optics based Raman spectroscopy device for transdermal blood analyte measurement (United States)

    Kong, Chae-Ryon; Barman, Ishan; Dingari, Narahara Chari; Kang, Jeon Woong; Galindo, Luis; Dasari, Ramachandra R.; Feld, Michael S.


    Due to its high chemical specificity, Raman spectroscopy has been considered to be a promising technique for non-invasive disease diagnosis. However, during Raman excitation, less than one out of a million photons undergo spontaneous Raman scattering and such weakness in Raman scattered light often require highly efficient collection of Raman scattered light for the analysis of biological tissues. We present a novel non-imaging optics based portable Raman spectroscopy instrument designed for enhanced light collection. While the instrument was demonstrated on transdermal blood glucose measurement, it can also be used for detection of other clinically relevant blood analytes such as creatinine, urea and cholesterol, as well as other tissue diagnosis applications. For enhanced light collection, a non-imaging optical element called compound hyperbolic concentrator (CHC) converts the wide angular range of scattered photons (numerical aperture (NA) of 1.0) from the tissue into a limited range of angles accommodated by the acceptance angles of the collection system (e.g., an optical fiber with NA of 0.22). A CHC enables collimation of scattered light directions to within extremely narrow range of angles while also maintaining practical physical dimensions. Such a design allows for the development of a very efficient and compact spectroscopy system for analyzing highly scattering biological tissues. Using the CHC-based portable Raman instrument in a clinical research setting, we demonstrate successful transdermal blood glucose predictions in human subjects undergoing oral glucose tolerance tests. PMID:22125761

  7. Combining Raman and laser induced breakdown spectroscopy by double pulse lasing. (United States)

    Lednev, Vasily N; Pershin, Sergey M; Sdvizhenskii, Pavel A; Grishin, Mikhail Ya; Fedorov, Alexander N; Bukin, Vladimir V; Oshurko, Vadim B; Shchegolikhin, Alexander N


    A new approach combining Raman spectrometry and laser induced breakdown spectrometry (LIBS) within a single laser event was suggested. A pulsed solid state Nd:YAG laser running in double pulse mode (two frequency-doubled sequential nanosecond laser pulses with dozens microseconds delay) was used to combine two spectrometry methods within a single instrument (Raman/LIBS spectrometer). First, a low-energy laser pulse (power density far below ablation threshold) was used for Raman measurements while a second powerful laser pulse created the plasma suitable for LIBS analysis. A short time delay between two successive pulses allows measuring LIBS and Raman spectra at different moments but within a single laser flash-lamp pumping. Principal advantages of the developed instrument include high quality Raman/LIBS spectra acquisition (due to optimal gating for Raman/LIBS independently) and absence of target thermal alteration during Raman measurements. A series of high quality Raman and LIBS spectra were acquired for inorganic salts (gypsum, anhydrite) as well as for pharmaceutical samples (acetylsalicylic acid). To the best of our knowledge, the quantitative analysis feasibility by combined Raman/LIBS instrument was demonstrated for the first time by calibration curves construction for acetylsalicylic acid (Raman) and copper (LIBS) in gypsum matrix. Combining ablation pulses and Raman measurements (LIBS/Raman measurements) within a single instrument makes it an efficient tool for identification of samples hidden by non-transparent covering or performing depth profiling analysis including remote sensing. Graphical abstract Combining Raman and laser induced breakdown spectroscopy by double pulse lasing.

  8. Characterization and discrimination of phenolic compounds using Fourier transform Raman spectroscopy and chemometric tools

    Directory of Open Access Journals (Sweden)

    Pompeu, DR.


    Full Text Available Description of the subject. Phenolic compounds (PCs are the most abundant secondary metabolites in plants. This work was part of a study that sought to develop rapid screening FT-Raman methods for identifying and quantifying classes and/or types of PCs in the dry extracts of plant products. Objectives. Fourier transform Raman spectroscopy (FT-Raman coupled with chemometric tools was used to characterize and discriminate four families of phenolic compounds: two important classes of phenolic acids, hydroxybenzoic and hydroxycinnamic acids, as well as their derivatives and flavonoids. Method. For this study, 25 standards of phenolic compounds were used (47 standards in total, taking account of the different brands. Repeatability and reproducibility studies were conducted to verify the Raman assignments of gallic acid. Raman characterization with the most significant spectral bands of phenolic compounds was done using spectra ranging from 1,800 to 50 cm-1. A Fisher test was applied to pre-processed Raman spectra (SNV and 20 Raman scattering signals were used to differentiate each class of phenolic compounds. Results. Hydroxybenzoic acids, hydroxycinnamic acids, their derivatives and flavonoids have been characterized by Raman spectroscopy; bands have been identified and differentiated within and between groups. Conclusions. The scattering intensities located around 1,600-1,699, 1,300-1,400 and below 200 cm-1 were responsible for differentiating 100% of phenolic compound families, classes and subclasses.

  9. Use of Raman spectroscopy in the analysis of nickel allergy (United States)

    Alda, Javier; Castillo-Martinez, Claudio; Valdes-Rodriguez, Rodrigo; Hernández-Blanco, Diana; Moncada, Benjamin; González, Francisco J.


    Raman spectra of the skin of subjects with nickel allergy are analyzed and compared to the spectra of healthy subjects to detect possible biochemical differences in the structure of the skin that could help diagnose metal allergies in a noninvasive manner. Results show differences between the two groups of Raman spectra. These spectral differences can be classified using principal component analysis. Based on these findings, a novel computational technique to make a fast evaluation and classification of the Raman spectra of the skin is presented and proposed as a noninvasive technique for the detection of nickel allergy.

  10. Raman spectroscopy and in situ Raman spectroelectrochemistry of bilayer ¹²C/¹³C graphene. (United States)

    Kalbac, Martin; Farhat, Hootan; Kong, Jing; Janda, Pavel; Kavan, Ladislav; Dresselhaus, Mildred S


    Bilayer graphene was prepared by the subsequent deposition of a (13)C single-layer graphene and a (12)C single-layer graphene on top of a SiO(2)/Si substrate. The bilayer graphene thus prepared was studied using Raman spectroscopy and in situ Raman spectroelectrochemistry. The Raman frequencies of the (13)C graphene bands are significantly shifted with respect to those of (12)C graphene, which allows us to investigate the single layer components of bilayer graphene individually. It is shown that the bottom layer of the bilayer graphene is significantly doped from the substrate, while the top layer does not exhibit a signature of the doping from the environment. The electrochemical doping has the same effect on the charge carrier concentration at the top and the bottom layer despite the top layer being the only layer in contact with the electrolyte. This is here demonstrated by essentially the same frequency shifts of the G and G' bands as a function of the electrode potential for both the top and bottom layers. Nevertheless, analysis of the intensity of the Raman modes showed an anomalous bleaching of the Raman intensity of the G mode with increasing electrode potential, which was not observed previously in one-layer graphene.

  11. Raman spectroscopy applied to identify metabolites in urine of physically active subjects. (United States)

    Moreira, Letícia Parada; Silveira, Landulfo; da Silva, Alexandre Galvão; Fernandes, Adriana Barrinha; Pacheco, Marcos Tadeu Tavares; Rocco, Débora Dias Ferraretto Moura


    Raman spectroscopy is a rapid and non-destructive technique suitable for biological fluids analysis. In this work, dispersive Raman spectroscopy has been employed as a rapid and nondestructive technique to detect the metabolites in urine of physically active subjects before and after vigorous 30min pedaling or running compared to sedentary subjects. For so, urine samples from 9 subjects were obtained before and immediately after physical activities and submitted to Raman spectroscopy (830nm excitation, 250mW laser power, 20s integration time) and compared to urine from 5 sedentary subjects. The Raman spectra of urine from sedentary showed peaks related to urea, creatinine, ketone bodies, phosphate and other nitrogenous compounds. These metabolic biomarkers presented peaks with different intensities in the urine of physically active individuals after exercises compared to before, measured by the intensity of selected peaks the Raman spectra, which means different concentrations after training. These peaks presented different intensity values for each subject before physical activity, also behaving differently compared to the post-training: some subjects presented increase while others decrease the intensity. Raman spectroscopy may allow the development of a rapid and non-destructive test for metabolic evaluation of the physical training in active and trained subjects using urine samples, allowing nutrition adjustment with the sport's performance. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Raman spectroscopy in solid state physics and material science. Theory, techniques and applications

    International Nuclear Information System (INIS)

    Lucazeau, G.; Abello, L.


    After a brief survey of the basic concepts of Raman scattering, we shall underline the specificities of the Raman spectroscopy as a characterization tool of solid materials. Most of the examples presented here have been selected among results which have been obtained recently in our laboratory. The micro-Raman technique provides a convenient way for investigating heterogeneities in ceramics and thin films. As a first example we show how the electric properties of the pure an doped BaCeO 3 perovskites are strongly dominated by the different phase transitions which take place in these compounds. We show in particular the advantage of the coupling of impedance and Raman spectroscopy when studying the influence of the chemical composition of the atmospheres and of the temperature on the electric properties of the ceramic. Unexpectedly, new concepts for explaining the phase transition mechanism in this structural family are provided by this study. A second example is borrowed from the characterization of a film made of a protonic conductor-doped polymer. A second kind of structural information which can be delivered by micro-Raman spectroscopy is related to the characterization of thermo-mechanical stresses in thin films of semi-conducting compounds in the Si-Ge system. It is well known that the gap and thus the electric properties are strongly dependent on the stress state of the material. The stress field induced either by an indenter, by a controlled flexion or by laser heating has been studied by Raman spectroscopy and is presented here. The pulsed Raman spectroscopy offers the possibility to characterize samples in strongly emissive atmospheres or submitted to strong perturbations of a short duration. The in situ characterization of diamond films in a plasma-assisted CVD reactor is briefly mentioned, another example is provided by a crystal of LaF 3 in which on a nanosecond scale different fluorescence processes are time-resolved and separated from the Raman

  13. Bithiophene radical cation: Resonance Raman spectroscopy and molecular orbital calculations

    DEFF Research Database (Denmark)

    Grage, M.M.-L.; Keszthelyi, T.; Offersgaard, J.F.


    The resonance Raman spectrum of the photogenerated radical cation of bithiophene is reported. The bithiophene radical cation was produced via a photoinduced electron transfer reaction between excited bithiophene and the electron acceptor fumaronitrile in a room temperature acetonitrile solution...... and the Raman spectrum excited in resonance with the absorption band at 425 nm. The spectrum was interpreted with the help of density functional theory calculations. (C) 1998 Elsevier Science B.V....

  14. Detection of explosive vapour using surface-enhanced Raman spectroscopy (United States)

    Fang, X.; Ahmad, S. R.


    A commercially available nano-structured gold substrate was used for activating surface-enhanced Raman scattering (SERS). Raman spectra of the vapour of explosive material, triacetonetriperoxide (TATP), at trace concentrations produced from adsorbed molecules on such surfaces have been studied. Prominent Raman lines of the explosive molecular species were recorded at a sample temperature of ˜35°C, which is near to human body temperature. For this study, the concentration of the adsorbed TATP molecules on the nano-structured surface was varied by heating the sample to different temperatures and exposing the substrate to the sample vapour for different lengths of time. The intensities of the Raman lines have been found to increase with the increase in temperature and also with the increase in the duration of exposure for a fixed temperature. However, as expected, the Raman intensities have been found to saturate at higher temperatures and longer exposures. These saturation effects of the strengths of the Raman lines in the SERS of TATP vapour have been investigated in this paper. The results indicate that the optimisation for vapour deposition on the surface could be a crucial factor for any quantitative estimate of the concentration of the molecular species adsorbed on the nano-structured substrates.

  15. Raman imaging and spectroscopy of individual single-wall carbon nanotubes (United States)

    Zhang, Li

    Single-wall carbon nanotubes (SWNT) are unique one-dimensional materials that are promising for many potential applications in various important areas. Their vibrational properties reflect the electron and phonon confinement as well as the structures of the tubes. Resonant Raman spectroscopy has been proven to be an exceedingly powerful tool for the characterization of the vibrational and electronic properties of SWNTs. This thesis focuses on the study of Raman spectroscopy of individual single carbon nanotubes. Single tube spectroscopy allows probing the structure dependent properties of SWNTs. A beam-scanning confocal Raman microscope system capable of large-area Raman imaging is first developed for characterizing SWNTs at the single tube level. Raman images and first-order Raman spectra of nanotubes, consisting of both semicoducting and metallic nanotubes, are systemically studied at room temperature in ambient air. The diameter of the nanotubes is determined from their radial breathing mode (RBM) frequency. A broad diameter distribution is observed for nanotubes synthesized by chemical vapor deposition. The tangential G mode Raman spectra of individual metallic nanotubes are found to exhibit a broad distribution of line shapes, which is attributed to shift of the Fermi level due to O2 adsorption. The doping dependence of Raman spectra of metallic tubes is further studied by both electrostatic gating and electrochemical gating. Significant changes in the G band Raman spectra of nanotubes are observed, suggesting the effect of doping on electron-phonon interaction. The observation of a gradual evolution of G band spectrum from a semiconducting type to the broad BWF type reveals evidence of phonon interaction between two G band modes. Raman imaging and Raman spectra of isolated SWNTs and single-layer graphenen are investigated at both room temperature and low temperature. The temperature-induced Raman spectral change of individual nanotubes is observed to be tube

  16. Raman Spectroscopy: An Emerging Tool in Neurodegenerative Disease Research and Diagnosis. (United States)

    Devitt, George; Howard, Kelly; Mudher, Amrit; Mahajan, Sumeet


    The pathogenesis underlining many neurodegenerative diseases remains incompletely understood. The lack of effective biomarkers and disease preventative medicine demands the development of new techniques to efficiently probe the mechanisms of disease and to detect early biomarkers predictive of disease onset. Raman spectroscopy is an established technique that allows the label-free fingerprinting and imaging of molecules based on their chemical constitution and structure. While analysis of isolated biological molecules has been widespread in the chemical community, applications of Raman spectroscopy to study clinically relevant biological species, disease pathogenesis, and diagnosis have been rapidly increasing since the past decade. The growing number of biomedical applications has shown the potential of Raman spectroscopy for detection of novel biomarkers that could enable the rapid and accurate screening of disease susceptibility and onset. Here we provide an overview of Raman spectroscopy and related techniques and their application to neurodegenerative diseases. We further discuss their potential utility in research, biomarker detection, and diagnosis. Challenges to routine use of Raman spectroscopy in the context of neuroscience research are also presented.

  17. Measurement of the Euler Angles of Wurtzitic ZnO by Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Wu Liu


    Full Text Available A Raman spectroscopy-based step-by-step measuring method of Euler angles φ,θ,and  ψ was presented for the wurtzitic crystal orientation on a microscopic scale. Based on the polarization selection rule and coordinate transformation theory, a series of analytic expressions for the Euler angle measurement using Raman spectroscopy were derived. Specific experimental measurement processes were presented, and the measurement of Raman tensor elements and Euler angles of the ZnO crystal were implemented. It is deduced that there is a trigonometric functional relationship between the intensity of each Raman bands of wurtzite crystal and Euler angle ψ, the polarization direction of incident light under different polarization configurations, which can be used to measure the Euler angles. The experimental results show that the proposed method can realize the measurement of Euler angles for wurtzite crystal effectively.

  18. High-temperature and high-pressure cubic zirconia anvil cell for Raman spectroscopy. (United States)

    Chen, Jinyang; Zheng, Haifei; Xiao, Wansheng; Zeng, Yishan


    A simple and inexpensive cubic zirconia anvil cell has been developed for the performance of in situ Raman spectroscopy up to the conditions of 500 degrees C and 30 kbar pressure. The design and construction of this cell are fully described, as well as its applications for Raman spectroscopy. Molybdenum heater wires wrapped around ceramic tubes encircling two cubic zirconia anvils are used to heat samples, and the temperatures are measured and controlled by a Pt-PtRh thermocouple adhered near the sample chamber and an intelligent digital control apparatus. With this cell, Raman spectroscopic measurements have been satisfactorily performed on water at 6000 bar pressure to 455 degrees C and on ice of room temperature to 24 kbar, in which the determinations of pressures make use of changes of the A1 Raman modes of quartz and the shift of the sharpline (R-line) luminescence of ruby, respectively.

  19. Non-invasive sex assessment in bovine semen by Raman spectroscopy (United States)

    De Luca, A. C.; Managó, S.; Ferrara, M. A.; Rendina, I.; Sirleto, L.; Puglisi, R.; Balduzzi, D.; Galli, A.; Ferraro, P.; Coppola, G.


    X- and Y-chromosome-bearing sperm cell sorting is of great interest, especially for animal production management systems and genetic improvement programs. Here, we demonstrate an optical method based on Raman spectroscopy to separate X- and Y-chromosome-bearing sperm cells, overcoming many of the limitations associated with current sex-sorting protocols. A priori Raman imaging of bull spermatozoa was utilized to select the sampling points (head-neck region), which were then used to discriminate cells based on a spectral classification model. Main variations of Raman peaks associated with the DNA content were observed together with a variation due to the sex membrane proteins. Next, we used principal component analysis to determine the efficiency of our device as a cell sorting method. The results (>90% accuracy) demonstrated that Raman spectroscopy is a powerful candidate for the development of a highly efficient, non-invasive, and non-destructive tool for sperm sexing.

  20. Rapid discrimination of newly isolated Bacillales with industrial applications using Raman spectroscopy

    International Nuclear Information System (INIS)

    Deng, A H; Sun, Z P; Zhang, G Q; Wu, J; Wen, T Y


    Members of the bacterial order Bacillales have been of great interest for agricultural, horticultural, industrial and medical applications because of their capacity to produce various extracellular enzymes. One of the challenges for Bacillales study is to rapidly and effectively identify and characterize newly isolated strains. In the present study, Raman spectroscopy was performed to identify 14 Bacillales strains isolated from Tibet, China. The biochemical properties of each isolate were characterized, and several Raman bands corresponding to nucleic acids, proteins or saccharides were different between isolates. Multivariate analysis of 112 Raman spectra clearly revealed that all 14 isolates were clustered into 3 groups, which was in accordance with the phylogenetic analysis of their 16S rRNA genes. Our results suggest that Raman spectroscopy is an effective and promising approach that could quickly discriminate different phylogenetic groups of Bacillales

  1. Non-invasive sex assessment in bovine semen by Raman spectroscopy

    International Nuclear Information System (INIS)

    De Luca, A C; Managó, S; Ferrara, M A; Rendina, I; Sirleto, L; Coppola, G; Puglisi, R; Balduzzi, D; Galli, A; Ferraro, P


    X- and Y-chromosome-bearing sperm cell sorting is of great interest, especially for animal production management systems and genetic improvement programs. Here, we demonstrate an optical method based on Raman spectroscopy to separate X- and Y-chromosome-bearing sperm cells, overcoming many of the limitations associated with current sex-sorting protocols. A priori Raman imaging of bull spermatozoa was utilized to select the sampling points (head-neck region), which were then used to discriminate cells based on a spectral classification model. Main variations of Raman peaks associated with the DNA content were observed together with a variation due to the sex membrane proteins. Next, we used principal component analysis to determine the efficiency of our device as a cell sorting method. The results (>90% accuracy) demonstrated that Raman spectroscopy is a powerful candidate for the development of a highly efficient, non-invasive, and non-destructive tool for sperm sexing. (letters)

  2. Microfluidic device for continuous single cells analysis via Raman spectroscopy enhanced by integrated plasmonic nanodimers

    KAUST Repository

    Perozziello, Gerardo


    In this work a Raman flow cytometer is presented. It consists of a microfluidic device that takes advantages of the basic principles of Raman spectroscopy and flow cytometry. The microfluidic device integrates calibrated microfluidic channels- where the cells can flow one-by-one -, allowing single cell Raman analysis. The microfluidic channel integrates plasmonic nanodimers in a fluidic trapping region. In this way it is possible to perform Enhanced Raman Spectroscopy on single cell. These allow a label-free analysis, providing information about the biochemical content of membrane and cytoplasm of the each cell. Experiments are performed on red blood cells (RBCs), peripheral blood lymphocytes (PBLs) and myelogenous leukemia tumor cells (K562). © 2015 Optical Society of America.

  3. Detection and quantitative analysis of ferrocyanide and ferricyanide: FY 93 Florida State University Raman spectroscopy report

    International Nuclear Information System (INIS)

    Mann, C.K.; Vickers, T.J.


    This report provides a summary of work to develop and investigate the feasibility of using Raman spectroscopy with tank waste materials. It contains Raman spectra from organics, such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetetraacteic acid (HEDTA), imino diacetic acid (IDA), kerosene, tributyl phosphate (TBP), acetone and butanol, anticipated to be present in tank wastes and spectra from T-107 real and BY-104 simulant materials. The results of investigating Raman for determining moisture content in tank materials are also presented. A description of software algorithms developed to process Raman spectra from a dispersive grating spectrometer system and an in initial design for a data base to support qualitative and quantitative application of remote Raman sensing with tank wastes

  4. Detection and quantitative analysis of ferrocyanide and ferricyanide: FY 93 Florida State University Raman spectroscopy report

    Energy Technology Data Exchange (ETDEWEB)

    Mann, C.K.; Vickers, T.J. [Florida State Univ., Tallahassee, FL (United States). Dept. of Chemistry


    This report provides a summary of work to develop and investigate the feasibility of using Raman spectroscopy with tank waste materials. It contains Raman spectra from organics, such as ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetetraacteic acid (HEDTA), imino diacetic acid (IDA), kerosene, tributyl phosphate (TBP), acetone and butanol, anticipated to be present in tank wastes and spectra from T-107 real and BY-104 simulant materials. The results of investigating Raman for determining moisture content in tank materials are also presented. A description of software algorithms developed to process Raman spectra from a dispersive grating spectrometer system and an in initial design for a data base to support qualitative and quantitative application of remote Raman sensing with tank wastes.

  5. Application of NIR Raman spectroscopy for detecting and characterizing early dental caries (United States)

    Ko, A. C.; Choo-Smith, L.-P.; Zhu, R.; Hewko, M.; Dong, C.; Cleghorn, B.; Sowa, M. G.


    Early dental caries detection facilitates implementation of non-surgical methods for arresting caries progression and promoting tooth remineralization. We present a method based on Raman spectroscopy with near-IR laser excitation to provide biochemical contrast for detecting and characterizing incipient carious lesions found in extracted human teeth. Changes in Raman spectra are observed in PO 4 3- vibrations arising from hydroxyapatite of mineralized tooth tissue. Examination of various intensities of the PO 4 3- ν2, ν3, ν4 vibrations showed consistent increased intensities in spectra of carious lesions compared to sound enamel. The spectral changes are attributed to demineralization-induced alterations of enamel crystallite morphology and/or orientation. This hypothesis is supported by reduced Raman polarization anisotropy derived from polarized Raman spectra of carious lesions. Polarized Raman spectral imaging of carious lesions found on whole (i.e. un-sectioned) tooth samples will also be presented.

  6. A critical assessment of visual identification of marine microplastic using Raman spectroscopy for analysis improvement

    DEFF Research Database (Denmark)

    Lenz, Robin; Enders, Kristina; Stedmon, Colin


    (n = 1279) were spectroscopically confirmed being plastic. The percentage varied with type, colour and size of the MP. Fibres had a higher success rate (75%) than particles (64%).We tested Raman micro-spectroscopy applicability for MP identification with respect to varying chemical composition...... (additives), degradation state and organic matter coating. Partially UV-degraded postconsumer plastics provided identifiable Raman spectra for polymers most common among marine MP, i.e. polyethylene and polypropylene...

  7. Low-loss tunable all-in-fiber filter for Raman spectroscopy

    DEFF Research Database (Denmark)

    Brunetti, Anna Chiara; Scolari, Lara; Lund-Hansen, Toke


    We show a novel in-line Rayleigh-rejection filter for Raman spectroscopy, based on a solid-core Photonic Crystal Fiber (PCF) filled with a high-index material. The device is low-loss and thermally tunable, and allows for a strong attenuation of the Rayleigh line at 532nm and the transmission...... of the Raman lines in a broad wavenumber range....

  8. Raman spectroscopy for skin cancer diagnosis and characterisation of thin supported lipid films


    Larraona-Puy, Marta


    Raman spectroscopy is a powerful tool in oncological imaging. Optical biopsies in which an accurate diagnosis of the tumour areas is spectroscopically performed are especially interesting for application to skin cancer treatments. In the first part of this dissertation a study on automated Raman spectral imaging allowed accurate diagnosis and delineation of the borders of a common type of skin cancer, basal cell carcinoma (BCC). Automated detection and imaging of BCC in skin sections exci...

  9. In-situ investigation of the calcination process of mixed oxide xerogels with Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Panitz, J.C. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)


    The controlled calcination of materials derived by sol-gel reactions is important for the evolution of the final structure. Raman spectroscopy is an ideal tool for the identification of surface species under in-situ conditions, as demonstrated in the following for the example of a molybdenum oxide-silica xerogel. Raman spectra of this particular sample were recorded at temperatures as high as 1173 K, and compared with those of a reference material.(author) 3 figs., 4 refs.

  10. Applications of Fourier transform Raman and infrared spectroscopy in forensic sciences (United States)

    Kuptsov, Albert N.


    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.

  11. Raman spectroscopy for characterization of annealing of ion-implanted InP

    International Nuclear Information System (INIS)

    Myers, D.R.; Gourley, P.L.; Vaidyanathan, K.V.; Dunlap, H.L.


    Raman spectroscopy has been used as a noncontacting, nondestructive tool to evaluate the properties of Si + - and Be + implanted InP samples annealed at temperatures ranging from 600 to 750C using phospho-silicate glass (PSG) as the encapsulant. Carrier activation, carrier mobility and recovery of damage as a function of anneal temperature obtained from analysis of Raman data agree very well with independent electrical measurements. (author)

  12. Raman spectroscopy of gases with a Fourier transform spectrometer - The spectrum of D2 (United States)

    Jennings, D. E.; Weber, A.; Brault, J. W.


    Fourier transform spectrometry (FTS) is presently used to record the spontaneous incoherent laser Raman spectra of gases. The high resolution, sensitivity, calibration accuracy and spectral coverage achieved demonstrate the viability of FTS for Raman spectroscopy. Attention is given to the coefficients obtained by fitting measurements obtained from the spectrum of D2, containing both v = 0-0 and 1-0 transitions, to the Dunham (1932) expansion of the vibration-rotation energy levels.

  13. Differential laser-induced perturbation Raman spectroscopy: a comparison with Raman spectroscopy for analysis and classification of amino acids and dipeptides. (United States)

    Oztekin, Erman K; Smith, Sarah E; Hahn, David W


    Differential-laser induced perturbation spectroscopy (DLIPS) is a new spectral analysis technique for classification and identification, with key potential applications for analysis of complex biomolecular systems. DLIPS takes advantage of the complex ultraviolet (UV) laser–material interactions based on difference spectroscopy by coupling low intensity UV laser perturbation with a traditional spectroscopy probe. Here, we quantify the DLIPS performance using a Raman scattering probe in classification of basic constituents of collagenous tissues, namely, the amino acids glycine, L-proline, and L-alanine, and the dipeptides glycine–glycine, glycine–alanine and glycine–proline and compare the performance to a traditional Raman spectroscopy probe via several multivariate analyses. We find that the DLIPS approach yields an ~40% improvement in discrimination among these tissue building blocks. The effects of the 193-nm perturbation laser are further examined by assessing the photodestruction of targeted material molecular bonds. The DLIPS method with a Raman probe holds promise for future tissue diagnosis, either as a stand-alone technique or as part of an orthogonal biosensing scheme.

  14. Quantitative Evaluation of Acetaminophen in Oral Solutions by Dispersive Raman Spectroscopy for Quality Control


    Borio, Viviane G.; Vinha, RubensJr.; Nicolau, Renata A.; de Oliveira, Hueder Paulo M.; de Lima, Carlos J.; Silveira, LandulfoJr.


    This work used dispersive Raman spectroscopy to evaluate acetaminophen in commercially available formulations as an analytical methodology for quality control in the pharmaceutical industry. Raman spectra were collected using a near-infrared dispersive Raman spectrometer (830 nm, 50 mW, 20 s exposure time) coupled to a fiber optic probe. Solutions of acetaminophen diluted in excipient (70 to 120% of the commercial concentration of 200 mg/mL) were used to develop a calibration model based on p...

  15. Optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy (United States)

    Saleem, M.; Bilal, M.; Anwar, S.; Rehman, A.; Ahmed, M.


    We present the optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy. Raman spectra were acquired from 18 blood serum samples using a laser at 532 nm as the excitation source. A multivariate regression model based on partial least-squares regression is developed that uses Raman spectra to predict dengue infection with leave-one-sample-out cross validation. The prediction of dengue infection by our model yields correlation coefficient r2 values of 0.9998 between the predicted and reference clinical results. The model was tested for six unknown human blood sera and found to be 100% accurate in accordance with the clinical results.

  16. Environmental effects on the lignin model monomer, vanillyl alcohol, studied by raman spectroscopy

    DEFF Research Database (Denmark)

    Larsen, Kiki Lyster; Barsberg, Søren Talbro


    Structural analysis of plant materials, i.e., lignin, cellulose, hemicellulose, etc., supports the growing interest of their uses, e.g., as sources for biofuels or materials. Lignin is a main polymer formed from three phenolic presursors, containing none, one, or two OMe groups, i.e., H, G, and S...... units, respectively. Raman spectroscopy gives valuable knowledge on lignin and has a large potential for further developments. Thus in the present work we show how the use of electronic structure theory can support the study of environmental effects on lignin Raman bands. Raman spectra of the lignin...

  17. A comparative study on defect estimation using XPS and Raman spectroscopy in few layer nanographitic structures. (United States)

    Ganesan, K; Ghosh, Subrata; Gopala Krishna, Nanda; Ilango, S; Kamruddin, M; Tyagi, A K


    Defects in planar and vertically oriented nanographitic structures (NGSs) synthesized by plasma enhanced chemical vapor deposition (PECVD) have been investigated using Raman and X-ray photoelectron spectroscopy. While Raman spectra reveal the dominance of vacancy and boundary type defects respectively in vertical and planar NGSs, XPS provides additional information on vacancy related defect peaks in the C 1s spectrum, which originate from non-conjugated carbon atoms in the hexagonal lattice. Although an excellent correlation prevails between these two techniques, our results show that estimation of surface defects by XPS is more accurate than Raman analysis. Nuances of these techniques are discussed in the context of assessing defects in nanographitic structures.

  18. An exploratory study of human teeth enamel by using Ft-Raman spectroscopy

    International Nuclear Information System (INIS)

    Afishah Alias; Siti Rahayu Mohd Hashim; Mihaly, Judith; Julyannie Wajir; Fauziah Abdul Aziz


    Unaffected , affected and heavily affected teeth enamel were studied by using FT-Raman spectroscopy. The 14 permanent teeths enamel surface were measured randomly, resulting in total n = 43 FT-Raman spectra. The results obtained from FT-Raman spectra of heavily affected, affected and unaffected tooths enamel surfaces did not show any significant difference. In this study, Kruskal-Wallis and Wilcoxon rank sum tests were used to compare the intensity between the categories of enamel as well as the surfaces of teeth samples. (author)

  19. Optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy

    International Nuclear Information System (INIS)

    Saleem, M; Bilal, M; Anwar, S; Rehman, A; Ahmed, M


    We present the optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy. Raman spectra were acquired from 18 blood serum samples using a laser at 532 nm as the excitation source. A multivariate regression model based on partial least-squares regression is developed that uses Raman spectra to predict dengue infection with leave-one-sample-out cross validation. The prediction of dengue infection by our model yields correlation coefficient r 2 values of 0.9998 between the predicted and reference clinical results. The model was tested for six unknown human blood sera and found to be 100% accurate in accordance with the clinical results. (letter)

  20. Raman spectroscopy for rapid discrimination of Staphylococcus epidermidis clones related to medical device-associated infections

    International Nuclear Information System (INIS)

    Samek, O; Telle, H H; Harris, L G; Mack, D; Bloomfield, M


    We report on the potential application of Raman spectroscopy for the fast typing of Staphylococcus epidermidis (S. epidermidis) strains related to medical device-associated infections. In this study bacterial colonies were directly probed on culture plates and Raman spectra were recorded from volumes containing approximately 10 bacteria. The spectra contain information on the molecular composition of the whole bacteria, such as fatty acids, carbohydrates, proteins and nucleic acids, DNA as well as RNA. We demonstrate the potential to discriminate different S. epidermidis clones, even after only short Raman exposure/collection times

  1. Light depolarization effects in tip enhanced Raman spectroscopy of silicon (001 and gallium arsenide (001

    Directory of Open Access Journals (Sweden)

    P. G. Gucciardi


    Full Text Available We report on the effects of light depolarization induced by sharp metallic tips in Tip-Enhanced Raman Spectroscopy (TERS. Experiments on Si(001 and GaAs(001 crystals show that the excitation field depolarization induces a selective enhancement of specific Raman modes, depending on their Raman tensor symmetry. A complete polarization analysis of the light backscattered from the tip confirms the TERS findings. The spatial confinement of the depolarization field is studied and its dependence on the excitation wavelength and power are explored.

  2. Assessment of argon ion laser dispersive Raman spectroscopy for hot cell applications

    International Nuclear Information System (INIS)

    Crawford, B.A.


    Characterization of high-level waste tank materials at Hanford is conducted to support safety assessments and waste treatment activities. Raman spectroscopy is expected to give chemical species information which may assist in defining layering in tank waste. This report describes the dispersive Raman system used in this year's investigation and the methology used to collect and evaluate data taken on tank waste samples. The current argon-ion Raman system was found not to be suitable for screening of tank cores, owing to silica interference, fluorescence interferences, and the extensive time required to collect and treat the data. Recommendations are given for further development

  3. Discriminating basal cell carcinoma from its surrounding tissue by Raman spectroscopy. (United States)

    Nijssen, Annieke; Bakker Schut, Tom C; Heule, Freerk; Caspers, Peter J; Hayes, Donal P; Neumann, Martino H A; Puppels, Gerwin J


    The objective of this in vitro study was to explore the applicability of Raman spectroscopy to distinguish basal cell carcinoma from its surrounding noncancerous tissue; therefore, identifying possibilities for the development of an in vivo diagnostic technique for tumor border demarcation. Raman spectra were obtained in a two-dimensional grid from unstained frozen sections of 15 basal cell carcinoma specimens. Pseudo-color Raman images were generated by multivariate statistical analysis and clustering analysis of spectra and compared with histopathology. In this way a direct link between histologically identifiable skin layers and structures and their Raman spectra was made. A tissue classification model was developed, which discriminates between basal cell carcinoma and surrounding nontumorous tissue, based on Raman spectra. The logistic regression model, shows a 100% sensitivity and 93% selectivity for basal cell carcinoma. The Raman spectra were, furthermore, used to obtain information about the differences in molecular composition between different skin layers and structures. An interesting finding was that in four samples of nodular basal cell carcinoma, the collagen signal contribution in spectra of dermis close to a basal cell carcinoma, was markedly reduced. The study demonstrates the sensitivity of Raman spectroscopy to biochemical changes in tissue accompanying malignancy, resulting in a high accuracy when discriminating between basal cell carcinoma and noncancerous tissue.

  4. Osteoarthritis screening using Raman spectroscopy of dried human synovial fluid drops (United States)

    Esmonde-White, Karen A.; Mandair, Gurjit S.; Esmonde-White, Francis W. L.; Raaii, Farhang; Roessler, Blake J.; Morris, Michael D.


    We describe the use of Raman spectroscopy to investigate synovial fluid drops deposited onto fused silica microscope slides. This spectral information can be used to identify chemical changes in synovial fluid associated with osteoarthritis (OA) damage to knee joints. The chemical composition of synovial fluid is predominately proteins (enzymes, cytokines, or collagen fragments), glycosaminoglycans, and a mixture of minor components such as inorganic phosphate crystals. During osteoarthritis, the chemical, viscoelastic and biological properties of synovial fluid are altered. A pilot study was conducted to determine if Raman spectra of synovial fluid correlated with radiological scoring of knee joint damage. After informed consent, synovial fluid was drawn and x-rays were collected from the knee joints of 40 patients. Raman spectra and microscope images were obtained from the dried synovial fluid drops using a Raman microprobe and indicate a coarse separation of synovial fluid components. Individual protein signatures could not be identified; Raman spectra were useful as a general marker of overall protein content and secondary structure. Band intensity ratios used to describe protein and glycosaminoglycan structure were used in synovial fluid spectra. Band intensity ratios of Raman spectra indicate that there is less ordered protein secondary structure in synovial fluid from the damage group. Combination of drop deposition with Raman spectroscopy is a powerful approach to examining synovial fluid for the purposes of assessing osteoarthritis damage.

  5. Use of low-frequency Raman spectroscopy and chemometrics for the quantification of crystallinity in amorphous griseofulvin tablets

    DEFF Research Database (Denmark)

    Mah, Pei T.; Fraser, Sara J.; Reish, Matthew E.


    drug is quantified using low-frequency Raman spectroscopy in concert with chemometrics for the first time. Importantly, these data are directly compared to simultaneously obtained mid-frequency Raman spectra, as well as to FT-Raman data, which is commonly used for such quantification. Griseofulvin...

  6. Analysis of phthalate ester content in poly(vinyl chloride) plastics by means of Fourier transform Raman spectroscopy

    DEFF Research Database (Denmark)

    Nørbygaard, Thomas; Berg, Rolf W.


    Fourier transform (FT) Raman spectroscopy is applied to a range of phthalate ester plasticizers in pure form as well as in poly(vinyl chloride) (PVC) samples. It is found that phthalate esters as a group can be identified by a set of six characteristic Raman bands. FT-Raman spectra of 22 phthalate...

  7. Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei


    We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950 cm-1 1750 to 3600 cm-1) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600 cm-1 within 1.0 s with a spectral resolution of 3 to 6 cm-1 during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

  8. Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy. (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei


    We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950  cm⁻¹; 1750 to 3600  cm⁻¹) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600  cm⁻¹ within 1.0 s with a spectral resolution of 3 to 6  cm⁻¹ during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

  9. Raman and IR Spectroscopy Studies on Propane at Pressures of Up to 40 GPa. (United States)

    Kudryavtsev, Daniil; Serovaiskii, Alexander; Mukhina, Elena; Kolesnikov, Anton; Gasharova, Biliana; Kutcherov, Vladimir; Dubrovinsky, Leonid


    Raman and IR spectroscopy studies on propane were performed at pressures of up to 40 GPa at ambient temperatures using the diamond anvil cell technique. Propane undergoes three phase transitions at 6.4(5), 14.5(5), and 26.5(5) GPa in Raman spectroscopy and at 7.0(5), 14.0(5), and 27.0(5) GPa in IR spectroscopy. The phase transitions were identified using the Raman and IR splitting modes and the appearance or disappearance of peaks, which clearly corresponded to the changes in the frequencies of the modes as the pressure changed. Our results demonstrate the complex high-pressure behavior of solid propane.

  10. Raman spectroscopy and optical trapping of 20 nm polystyrene particles in plasmonic nanopores (United States)

    Kerman, Sarp; Chen, Chang; Li, Yi; Lagae, Liesbet; Stakenborg, Tim; Van Dorpe, Pol


    The detection and identification of nanoparticles has caught the attention in the last decade due to its potential application on small bio-particles. Raman spectroscopy stands out as a label-free technique for the detection of such particles. However, it may require a high concentration of particles. In a solution with low concentration of particles to detect Raman spectroscopy, the number of particles in the detection area can be increased by optical trapping. The optical trapping force applied to a dielectric nanoparticle is proportional to the gradient of the optical intensity field. Plasmonic nanopores are efficient platforms for trapping nanoparticles due to highly enhanced localized field and its high gradient. Here, we report our work on the optical trapping and assembly of 20 nm polystyrene nanoparticles in a plasmonic nanopore and its detection by Raman spectroscopy.

  11. Metal-dielectric-CNT nanowires for surface-enhanced Raman spectroscopy (United States)

    Bond, Tiziana C.; Altun, Ali; Park, Hyung Gyu


    A sensor with a substrate includes nanowires extending vertically from the substrate, a hafnia coating on the nanowires that provides hafnia coated nanowires, and a noble metal coating on the hafnia coated nanowires. The top of the hafnia and noble metal coated nanowires bent onto one another to create a canopy forest structure. There are numerous randomly arranged holes that let through scattered light. The many points of contact, hot spots, amplify signals. The methods include the steps of providing a Raman spectroscopy substrate, introducing nano crystals to the Raman spectroscopy substrate, growing a forest of nanowires from the nano crystals on the Raman spectroscopy substrate, coating the nanowires with hafnia providing hafnia coated nanowires, and coating the hafnia coated nanowires with a noble metal or other metal.

  12. Race Differentiation Based on Raman Spectroscopy of Semen Traces for Forensic Purposes. (United States)

    Muro, Claire K; Lednev, Igor K


    Several novel methods to determine externally visible characteristics of body fluid donors have been developed in recent years. These tests can help forensic investigators make predictions about the appearance of a suspect or victim, such as their sex, race, hair color, or age. While their potential benefit is undeniable, these methods destroy the physical evidence in the process. Raman spectroscopy has recently been used as a nondestructive technique to test for many of these characteristics. Here, we present the results from a study to determine the race of semen donors. Using Raman spectroscopy and multivariate data analysis, we were able to build a statistical model that accurately identified the race of all 18 semen donors in the calibration data set, as well as seven additional external validation donors. These results demonstrate Raman spectroscopy's potential to differentiate Caucasian and Black semen donors using chemometrics.

  13. Stand-off laser Raman spectroscopy and its advancement in explosives detection (United States)

    Liu, Sheng-run; Xue, Bin; Li, Yi-zhe; Wang, Hui


    The explosives detection has been a hot and difficult issue in the field of security it is particularly important to detect explosives quickly and reliably. There are many methods to detect explosives currently, stand-off Raman spectroscopy is one of the most promising and practical technologies, this technique can be used for non-contact and nondestructive detection, ensure the safety of attendants, at the same time the precision and speed of detection are also very high and be characterized by rapid response. This paper mainly gives an account of the fundamental principle of Raman spectroscopy, as well as recount major challenges of Standoff Laser Raman Spectroscopy applied in explosives detection and corresponding solutions. From the perspective of the system, this paper sums up related theories and techniques of the excitation laser and telescopic system etc.. Ultimately, a brief analysis and summary of the development trend of this technology is given.

  14. Interference-free optical detection for Raman spectroscopy (United States)

    Nguyen, Quang-Viet (Inventor); Fischer, David G (Inventor); Kojima, Jun (Inventor)


    An architecture for spontaneous Raman scattering (SRS) that utilizes a frame-transfer charge-coupled device (CCD) sensor operating in a subframe burst gating mode to realize time-resolved combustion diagnostics is disclosed. The technique permits all-electronic optical gating with microsecond shutter speeds (<5 .mu.s), without compromising optical throughput or image fidelity. When used in conjunction with a pair of orthogonally-polarized excitation lasers, the technique measures time-resolved vibrational Raman scattering that is minimally contaminated by problematic optical background noise.

  15. Metallodrug induced apoptotic cell death and survival attempts are characterizable by Raman spectroscopy (United States)

    le Roux, K.; Prinsloo, L. C.; Meyer, D.


    Chrysotherapeutics are under investigation as new or additional treatments for different types of cancers. In this study, gold complexes were investigated for their anticancer potential using Raman spectroscopy. The aim of the study was to determine whether Raman spectroscopy could be used for the characterization of metallodrug-induced cell death. Symptoms of cell death such as decreased peak intensities of proteins bonds and phosphodiester bonds found in deoxyribose nucleic acids were evident in the principal component analysis of the spectra. Vibrational bands around 761 cm-1 and 1300 cm-1 (tryptophan, ethanolamine group, and phosphatidylethanolamine) and 1720 cm-1 (ester bonds associated with phospholipids) appeared in the Raman spectra of cervical adenocarcinoma (HeLa) cells after metallodrug treatment. The significantly (p mechanism of cancer cells under chemical stress. Cancer cells excrete chemotherapeutics to improve their chances of survival and utilize glucose to achieve this. Raman spectroscopy was able to monitor a survival strategy of cancer cells in the form of glucose uptake to alleviate chemical stress. Raman spectroscopy was invaluable in obtaining molecular information generated by biomolecules affected by anticancer metallodrug treatments and presents an alternative to less reproducible, conventional biochemical assays for cytotoxicity analyses.

  16. A combined laser-induced breakdown and Raman spectroscopy Echelle system for elemental and molecular microanalysis

    Energy Technology Data Exchange (ETDEWEB)

    Hoehse, Marek [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Mory, David [LTB Lasertechnik Berlin, Rudower Chaussee 29, 12489 Berlin (Germany); Florek, Stefan [ISAS - Institute for Analytical Science, Albert-Einstein-Str. 9, D-12489 Berlin (Germany); Weritz, Friederike [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Gornushkin, Igor, E-mail: igor.gornushkin@bam.d [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Panne, Ulrich [BAM Federal Institute for Materials Research and Testing, Richard-Willstaetter Str. 11, D-12489 Berlin (Germany); Humboldt Universitaet zu Berlin, Chemistry Department, Brook-Taylor-Strasse 2, D-12489 Berlin (Germany)


    Raman and laser-induced breakdown spectroscopy is integrated into a single system for molecular and elemental microanalyses. Both analyses are performed on the same approx 0.002 mm{sup 2} sample spot allowing the assessment of sample heterogeneity on a micrometric scale through mapping and scanning. The core of the spectrometer system is a novel high resolution dual arm Echelle spectrograph utilized for both techniques. In contrast to scanning Raman spectroscopy systems, the Echelle-Raman spectrograph provides a high resolution spectrum in a broad spectral range of 200-6000 cm{sup -1} without moving the dispersive element. The system displays comparable or better sensitivity and spectral resolution in comparison to a state-of-the-art scanning Raman microscope and allows short analysis times for both Raman and laser induced breakdown spectroscopy. The laser-induced breakdown spectroscopy performance of the system is characterized by ppm detection limits, high spectral resolving power (15,000), and broad spectral range (290-945 nm). The capability of the system is demonstrated with the mapping of heterogeneous mineral samples and layer by layer analysis of pigments revealing the advantages of combining the techniques in a single unified set-up.

  17. Identifying a common origin of toner printed counterfeit banknotes by micro-Raman spectroscopy. (United States)

    Skenderović Božičević, Martina; Gajović, Andreja; Zjakić, Igor


    This study explores the applicability of micro-Raman spectroscopy as a non-destructive technique for the analysis of color toner printed counterfeits. The main aim of the research paper was to find out whether Raman spectroscopy is a suitable method for establishing the connection between different specimens of counterfeits suspected to be printed with the same toner on the same machine. Specimens of different types of toners printed on different types of paper are analyzed by means of the micro-Raman spectroscopy system with the excitation line at 514.5 nm. For each specimen cyan, magenta and yellow toners are analyzed separately. The yellow toners displayed the most distinctive Raman spectra. The results show that micro-Raman spectroscopy can be successfully applied as a method for the analysis of color toner printed counterfeits, such as banknotes and documents, in order to establish links between more or less different specimens of counterfeits by measuring the properties of a color toner. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  18. Using Raman spectroscopy and SERS for in situ studies of rhizosphere bacteria

    Energy Technology Data Exchange (ETDEWEB)

    Mohseni, Hooman; Agahi, Massoud H.; Razeghi, Manijeh; Polisetti, Sneha; Baig, Nameera; Bible, Amber; Morrell-Falvey, Jennifer; Doktycz, Mitchel; Bohn, Paul W.


    Bacteria colonize plant roots to form a symbiotic relationship with the plant and can play in important role in promoting plant growth. Raman spectroscopy is a useful technique to study these bacterial systems and the chemical signals they utilize to interact with the plant. We present a Raman study of Pantoea YR343 that was isolated from the rhizosphere of Populus deltoides (Eastern Cottonwood). Pantoea sp. YR343 produce yellowish carotenoid pigment that play a role in protection against UV radiation, in the anti-oxidative pathways and in membrane fluidity. Raman spectroscopy is used to non-invasively characterize the membrane bound carotenoids. The spectra collected from a mutant strain created by knocking out the crtB gene that encodes a phytoene synthase responsible for early stage of carotenoid biosynthesis, lack the carotenoid peaks. Surface Enhanced Raman Spectroscopy is being employed to detect the plant phytoharmone indoleacetic acid that is synthesized by the bacteria. This work describes our recent progress towards utilizing Raman spectroscopy as a label free, non-destructive method of studying plant-bacteria interactions in the rhizosphere.

  19. Remote Raman Spectroscopy of Minerals at Elevated Temperature Relevant to Venus Exploration (United States)

    Sharma, Shiv K.; Misra, Anupam K.; Singh, Upendra N.


    We have used a remote time-resolved telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals at high temperature to 970 K. Remote Raman measurements were made with samples at 9-meter in side a high-temperature furnace by gating the ICCD detector with 2 micro-sec gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high-temperature spectra. In the case of gypsum, Raman spectral fingerprints of CaSO4.H2O at 518 K were observed due to dehydration of gypsum. In the case of dolomite, partial mineral dissociation was observed at 973 K at ambient pressure indicating that some of the dolomite might survive on Venus surface that is at approximately 750 K and 92 atmospheric pressure. Time-resolved Raman spectra of low clino-enstatite (MgSiO3) measured at 75 mm from the sample in side the high-temperature furnace also show that the Raman lines remains sharp and well defined in the high temperature spectra. These high-temperature remote Raman spectra of minerals show that time-resolved Raman spectroscopy can be used as a potential tool for exploring Venus surface mineralogy at shorter (75 mm) and long (9 m) distances from the samples both during daytime and nighttime. The remote Raman system could also be used for measuring profiles of molecular species in the dense Venus atmosphere during descent as well as on the surface.

  20. Ultraviolet resonance Raman spectroscopy for the detection of cocaine in oral fluid (United States)

    D'Elia, Valentina; Montalvo, Gemma; Ruiz, Carmen García; Ermolenkov, Vladimir V.; Ahmed, Yasmine; Lednev, Igor K.


    Detecting and quantifying cocaine in oral fluid is of significant importance for practical forensics. Up to date, mainly destructive methods or biochemical tests have been used, while spectroscopic methods were only applied to pretreated samples. In this work, the possibility of using resonance Raman spectroscopy to detect cocaine in oral fluid without pretreating samples was tested. It was found that ultraviolet resonance Raman spectroscopy with 239-nm excitation allows for the detection of cocaine in oral fluid at 10 μg/mL level. Further method development will be needed for reaching the practically useful levels of cocaine detection.

  1. Photoluminescence and Raman spectroscopy characterization of boron- and nitrogen-doped 6H silicon carbide

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Liu, Chuan


    Boron - and nitrogen-doped 6H silicon carbide epilayers grown on low off-axis 6H silicon carbide substrates have been characterized by photoluminescence and Raman spectroscopy. Combined with secondary ion mass spectrometry results, preferable doping type and optimized concentration could be propo......Boron - and nitrogen-doped 6H silicon carbide epilayers grown on low off-axis 6H silicon carbide substrates have been characterized by photoluminescence and Raman spectroscopy. Combined with secondary ion mass spectrometry results, preferable doping type and optimized concentration could...

  2. Analysis of disulphide bonds found in human hair by Raman spectroscopy (United States)

    Pina-Ruiz, A. L.; Cordova-Fraga, T.; Plascencia-Castro, A. S.; Hernandez-Rayas, A.; Ruvalcaba, J. M.


    Raman spectroscopy offers information-rich spectra, making it a technique easy to use in areas such as biology, chemistry, and in the field. Human hair spectra has been recorded obtaining interesting information about its composition. Correlating information obtained from these spectra to bone health and determining if Raman spectroscopy could be used as a diagnostic tool of bone health is proposed. Spectra from healthy women were compared to the spectra of women who have suffered a bone fracture, all which were aged 39-60. This technique has potential to become a regular diagnostic tool and further investigation to improve and validate this method are needed.

  3. Noise and artifact characterization of in vivo Raman spectroscopy skin measurements. (United States)

    Ramírez-Elías, Miguel G; Alda, Javier; González, Francisco J


    In this work principal component analysis (PCA), a multivariate pattern recognition technique, is used to characterize the noise contribution of the experimental apparatus and two commonly used methods for fluorescence removal used in biomedical Raman spectroscopy measurements. These two methods are a fifth degree polynomial fitting and an iterative variation of it commonly known as the Vancouver method. The results show that the noise in Raman spectroscopy measurements is related to the spectral resolution of the measurement equipment, the intrinsic variability of the biological measurements, and the fluorescence removal algorithm used.

  4. Photoluminescence and Raman Spectroscopy Characterization of Boron- and Nitrogen-Doped 6H Silicon Carbide

    DEFF Research Database (Denmark)

    Ou, Yiyu; Jokubavicius, Valdas; Liu, Chuan


    Nitrogen-boron doped 6H-SiC epilayers grown on low off-axis 6H-SiC substrates have been characterized by photoluminescence and Raman spectroscopy. The photoluminescence results show that a doping larger than 1018 cm-3 is favorable to observe the luminescence and addition of nitrogen is resulting...... in an increased luminescence. A dopant concentration difference larger than 4x1018 cm-3 is proposed to achieve intense photoluminescence. Raman spectroscopy further confirmed the doping type and concentrations for the samples. The results indicate that N-B doped SiC is being a good wavelength converter in white...

  5. Raman spectroscopy of optical properties in CdS thin films

    Directory of Open Access Journals (Sweden)

    Trajić J.


    Full Text Available Properties of CdS thin films were investigated applying atomic force microscopy (AFM and Raman spectroscopy. CdS thin films were prepared by using thermal evaporation technique under base pressure 2 x 10-5 torr. The quality of these films was investigated by AFM spectroscopy. We apply Raman scattering to investigate optical properties of CdS thin films, and reveal existence of surface optical phonon (SOP mode at 297 cm-1. Effective permittivity of mixture were modeled by Maxwell - Garnet approximation. [Projekat Ministarstva nauke Republike Srbije, br. 45003

  6. Rapid detection of chlorpyrifos pesticide residue concentration in agro-product using Raman spectroscopy (United States)

    Dhakal, Sagar; Peng, Yankun; Li, Yongyu; Chao, Kuanglin; Qin, Jianwei; Zhang, Leilei; Xu, Tianfeng


    Different chemicals are sprayed in fruits and vegetables before and after harvest for better yield and longer shelf-life of crops. Cases of pesticide poisoning to human health are regularly reported due to excessive application of such chemicals for greater economic benefit. Different analytical technologies exist to detect trace amount of pesticides in fruits and vegetables, but are expensive, sample destructive, and require longer processing time. This study explores the application of Raman spectroscopy for rapid and non-destructive detection of pesticide residue in agricultural products. Raman spectroscopy with laser module of 785 nm was used to collect Raman spectral information from the surface of Gala apples contaminated with different concentrations of commercially available organophosphorous (48% chlorpyrifos) pesticide. Apples within 15 days of harvest from same orchard were used in this study. The Raman spectral signal was processed by Savitzky-Golay (SG) filter for noise removal, Multiplicative Scatter Correction (MSC) for drift removal and finally polynomial fitting was used to eliminate the fluorescence background. The Raman spectral peak at 677 cm-1 was recognized as Raman fingerprint of chlorpyrifos. Presence of Raman peak at 677 cm-1 after fluorescence background removal was used to develop classification model (presence and absence of pesticide). The peak intensity was correlated with actual pesticide concentration obtained using Gas Chromatography and MLR prediction model was developed with correlation coefficient of calibration and validation of 0.86 and 0.81 respectively. Result shows that Raman spectroscopy is a promising tool for rapid, real-time and non-destructive detection of pesticide residue in agro-products.

  7. The determination of captopril in Solution by Raman spectroscopy (United States)

    Gao, Junxiang; Gu, Huaimin; Dong, Xiao; liu, fangfang


    Captopril, 1-[(2S)-3-mercapto-2-methyl propionyl]-Lproline, is an angiotensin converting enzyme (ACE) inhibitor, which reduces peripheral resistance and lowers blood pressure. It is widely used in the hypertensive ailments and incongestive heart failure treatment. Due to such crucial pharmacological importance, development of simple and accurate methods for the determination of captopril is desired. In this work, the normal Raman spectra of the captopril in different concentrations were studied, and the relationship between the Raman intensity and the concentrations of the captopril was quantificationally analysed. By selecting appropriate characteristic Raman bands of the cptopril, the solution of some captopril purchased in a local pharmacy was quantificationally determined. A quantificational linear relationship between the Raman intensity and the concentrations of captopril was obtained, and it is little affected by other compounds in the solution of captopril. This study provides an effective technique for the quantificational determination of captopril in solutions, and it has a potential application in the analysis of medicament.

  8. Subframe burst gating for Raman spectroscopy in combustion. (United States)

    Kojima, Jun; Fischer, David; Nguyen, Quang-Viet


    We describe an architecture for spontaneous Raman scattering utilizing a frame-transfer CCD sensor operating in a subframe burst-gating mode to realize time-resolved combustion diagnostics. The technique permits all-electronic optical gating with microsecond shutter speeds (noise.

  9. Raman spectroscopy in the analysis of cellulose nanomaterials (United States)

    Umesh P. Agarwal


    Cellulose nanomaterials (CNs) are new types of materials derived from celluloses and offer unique challenges and opportunities for Raman spectroscopic investigations. CNs can be classified into the categories of cellulose nanocrystals (CNCs, also known as cellulose whisker) and cellulose nanofibrils (CNFs, also known as nanofibrillated cellulose or NFCs) which when...

  10. Identification of Abnormal Stem Cells Using Raman Spectroscopy

    DEFF Research Database (Denmark)

    Harkness, Linda; Novikov, Sergey M; Beermann, Jonas


    The clinical use of stem cells in cell-based therapeutics for degenerative diseases requires development of criteria for defining normal stem cells to ensure safe transplantation. Currently, identification of abnormal from normal stem cells is based on extensive ex vivo and in vivo testing. Raman...

  11. Quantitative Raman spectroscopy for the analysis of carrot bioactives. (United States)

    Killeen, Daniel P; Sansom, Catherine E; Lill, Ross E; Eason, Jocelyn R; Gordon, Keith C; Perry, Nigel B


    Rapid quantitative near-infrared Fourier transform Raman analyses of the key phytonutrients in carrots, polyacetylenes and carotenoids, are reported here for the first time. Solvent extracts of 31 carrot lines were analyzed for these phytonutrients by conventional methods, polyacetylenes by GC-FID and carotenoids by visible spectrophotometry. Carotenoid concentrations were 0-5586 μg g(-1) dry weight (DW). Polyacetylene concentrations were 74-4846 μg g(-1) DW, highest in wild carrots. The polyacetylenes were falcarinol, 6-1237 μg g(-1) DW; falcarindiol, 42-3475 μg g(-1) DW; and falcarindiol 3-acetate, 27-649 μg g(-1) DW. Strong Raman bands for carotenoids gave good correlation to results by visible spectrophotometry. A chemometric model capable of quantitating carotenoids from Raman data was developed. A classification model for rapidly distinguishing carrots with high and low polyacetylene (limit of detection = 1400 μg g(-1)) concentrations based on Raman spectral intensity in the region of 2250 cm(-1) was produced.

  12. Fast Resonance Raman Spectroscopy of a Free Radical

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Pagsberg, Palle Bjørn; Hansen, K. B.


    The resonance Raman spectrum of a 10−3 molar solution of the stable diphenyl-pikryl-hydrazyl radical in benzene was obtained using a single laser pulse of 10 mJ energy and 600 ns duration from a flashlamp pumped tunable dye laser. Spectra were recorded using an image intensifier coupled to a TV...

  13. Chemical identity testing by remote-based dispersive Raman spectroscopy. (United States)

    Bugay, David E; Brush, Robert C


    The advent of robust, rugged, and current Good Manufacturing Practices (cGMP) compliant hand-held Raman spectrometers provides a wealth of opportunities for the analytical pharmaceutical chemist to bring the laboratory to the sample. This paper discusses the use of hand-held Raman spectrometers for the development of qualitative chemical identification methods for a number of well-known pharmaceutical products (tablets and capsules). Methods were developed on two different instruments and transferred to a third instrument for application of the methodology to independently obtained drug products. A novel decision algorithm is presented for the assessment of the correlation between the Raman spectrum of the unknown sample to the spectrum of the authentic reference material. This novel algorithm considers accuracy but more importantly precision (uncertainty/reliability), thus removing human bias that is associated with typical spectral searching approaches. The results presented in this paper show the reliability of developing, validating, and transferring chemical identification assays on hand-held Raman spectrometers.

  14. Lanthanum trilactate: Vibrational spectroscopic study - infrared/Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Švecová, M.; Novák, Vít; Bartůněk, V.; Člupek, M.


    Roč. 87, Nov (2016), s. 123-128 ISSN 0924-2031 Institutional support: RVO:61388963 Keywords : lanthanum trilactate * tris(2-hydroxypropanoato-O1,O2) * lanthanum tris[2-(hydroxy-kappa O)propanoato-kappa O] * Raman spectra * infrared spectra * DFT Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 1.740, year: 2016

  15. Summary of recent Raman Spectroscopy testing of SRS processes

    Energy Technology Data Exchange (ETDEWEB)

    Fondeur, F. F. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Lascola, R. J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); O' Rourke, P. E. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)


    This report describes several scoping projects conducted at SRNL using Raman spectroscopic methods for monitoring different aspects of nuclear waste and materials processing. One project examined the suitability of a Raman telescope for in situ measurement of solid residues in waste tanks. Characteristics evaluated for this equipment included radiation resistance, ease of use, and sensitivity. A second project monitored the nitrate content in liquid filtrate from the testing of a rotary microfilter using a fiber-based insertion probe. The third project made Raman measurements of various gases, including H2 and NOx, in the headspace of a vessel while dissolving aluminum coupons in nitric acid. Measurements followed the evolution of these species in real time. Although the majority of these projects occurred in the laboratory environment, SRNL has substantial experience with implementing other optical techniques into nuclear materials processing environments. The work described in this report shows the potential of the Raman technology to provide real time measurements of species such as nitrate or hydroxide during sludge washing or evolved gases such as hydrogen or NOx during waste processing.

  16. Effect of laser irradiation on cell function and its implications in Raman spectroscopy. (United States)

    Yuan, Xiaofei; Song, Yanqing; Song, Yizhi; Xu, Jiabao; Wu, Yinhu; Glidle, Andrew; Cusack, Maggie; Ijaz, Umer Z; Cooper, Jonathan M; Huang, Wei E; Yin, Huabing


    Lasers are instrumental in advanced bioimaging and Raman spectroscopy. However, they are also well known for their destructive effects on living organisms, leading to concerns about the adverse effects of laser technologies. To implement Raman spectroscopy for cell analysis and manipulation, such as Raman activated cell sorting, it is crucial to identify non-destructive conditions for living cells. Here, we evaluated quantitatively the effect of 532 nm laser irradiation on bacterial cell fate and growth at the single-cell level. Using a purpose-built microfluidic platform, we were able to quantify the growth characteristics i.e. specific growth rate and lag time of individual cells as well as the survival rate of a population in conjunction with Raman spectroscopy. Representative Gram-negative and Gram-positive species show a similar trend in response to laser irradiation dose. Laser irradiation could compromise physiological function of cells and the degree of destruction is both dose and strain dependent, ranging from reduced cell growth to a complete loss of cell metabolic activity and finally to physical disintegration. Gram-positive bacterial cells are more susceptible than Gram-negative bacterial strains to irradiation-induced damage. By directly correlating Raman acquisition with single cell growth characteristics, we provide evidence of non-destructive characteristics of Raman spectroscopy on individual bacterial cells. However, while strong Raman signals can be obtained without causing cell death, the variety of responses from different strains and from individual cells justify careful evaluation of Raman acquisition conditions if cell viability is critical. IMPORTANCE In Raman spectroscopy, the use of powerful monochromatic light in laser-based systems facilitates detection of the inherently weak signals. This allows environmentally and clinically relevant microorganisms to be measured at the single cell level. The significance of being able to perform

  17. Structure of polypropylene/polyethylene blends assessed by polarised PA-FTIR spectroscopy, polarised FT Raman spectroscopy and confocal Raman microscopy

    Czech Academy of Sciences Publication Activity Database

    Schmidt, Pavel; Dybal, Jiří; Ščudla, Jaroslav; Raab, Miroslav; Kratochvíl, Jaroslav; Eichhorn, K. J.; López-Quintana, S.


    Roč. 184, - (2002), s. 107-122 ISSN 1022-1360. [European Symposium on Polymer Spectroscopy /14./. Dresden, 02.09.2001-05.09.2001] R&D Projects: GA ČR GA106/97/1071; GA ČR GA203/97/0539; GA AV ČR KSK4050111; GA AV ČR IAA4050904 Institutional research plan: CEZ:AV0Z4050913 Keywords : polypropylene/polyethylene blends * polarized photoacoustic FTIR spectroscopy * confocal Raman microscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.758, year: 2002

  18. Polymorph characterization of active pharmaceutical ingredients (APIs) using low-frequency Raman spectroscopy. (United States)

    Larkin, Peter J; Dabros, Marta; Sarsfield, Beth; Chan, Eric; Carriere, James T; Smith, Brian C


    Polymorph detection, identification, and quantitation in crystalline materials are of great importance to the pharmaceutical industry. Vibrational spectroscopic techniques used for this purpose include Fourier transform mid-infrared (FT-MIR) spectroscopy, Fourier transform near-infrared (FT-NIR) spectroscopy, Raman spectroscopy, and terahertz (THz) and far-infrared (FIR) spectroscopy. Typically, the fundamental molecular vibrations accessed using high-frequency Raman and MIR spectroscopy or the overtone and combination of bands in the NIR spectra are used to monitor the solid-state forms of active pharmaceutical ingredients (APIs). The local environmental sensitivity of the fundamental molecular vibrations provides an indirect probe of the long-range order in molecular crystals. However, low-frequency vibrational spectroscopy provides access to the lattice vibrations of molecular crystals and, hence, has the potential to more directly probe intermolecular interactions in the solid state. Recent advances in filter technology enable high-quality, low-frequency Raman spectra to be acquired using a single-stage spectrograph. This innovation enables the cost-effective collection of high-quality Raman spectra in the 200-10 cm(-1) region. In this study, we demonstrate the potential of low-frequency Raman spectroscopy for the polymorphic characterization of APIs. This approach provides several benefits over existing techniques, including ease of sampling and more intense, information-rich band structures that can potentially discriminate among crystalline forms. An improved understanding of the relationship between the crystalline structure and the low-frequency vibrational spectrum is needed for the more widespread use of the technique.

  19. Correlative Raman spectroscopy and focused ion beam for targeted phase boundary analysis of titania polymorphs

    Energy Technology Data Exchange (ETDEWEB)

    Mangum, John S.; Chan, Lisa H.; Schmidt, Ute; Garten, Lauren M.; Ginley, David S.; Gorman, Brian P.


    Site-specific preparation of specimens using focused ion beam instruments for transmission electron microscopy is at the forefront of targeting regions of interest for nanoscale characterization. Typical methods of pinpointing desired features include electron backscatter diffraction for differentiating crystal structures and energy-dispersive X-Ray spectroscopy for probing compositional variations. Yet there are situations, notably in the titanium dioxide system, where these techniques can fail. Differentiating between the brookite and anatase polymorphs of titania is either excessively laborious or impossible with the aforementioned techniques. However, due to differences in bonding structure, Raman spectroscopy serves as an ideal candidate for polymorph differentiation. In this work, a correlative approach utilizing Raman spectroscopy for targeted focused ion beam specimen preparation was employed. Dark field imaging and diffraction in the transmission electron microscope confirmed the region of interest located via Raman spectroscopy and demonstrated the validity of this new method. Correlative Raman spectroscopy, scanning electron microscopy, and focused ion beam is shown to be a promising new technique for identifying site-specific preparation of nanoscale specimens in cases where conventional approaches do not suffice.

  20. Raman Spectroscopy of DNA Packaging in Individual Human Sperm Cells distinguishes Normal from Abnormal Cells

    Energy Technology Data Exchange (ETDEWEB)

    Huser, T; Orme, C; Hollars, C; Corzett, M; Balhorn, R


    Healthy human males produce sperm cells of which about 25-40% have abnormal head shapes. Increases in the percentage of sperm exhibiting aberrant sperm head morphologies have been correlated with male infertility, and biochemical studies of pooled sperm have suggested that sperm with abnormal shape may contain DNA that has not been properly repackaged by protamine during spermatid development. We have used micro-Raman spectroscopy to obtain Raman spectra from individual human sperm cells and examined how differences in the Raman spectra of sperm chromatin correlate with cell shape. We show that Raman spectra of individual sperm cells contain vibrational marker modes that can be used to assess the efficiency of DNA-packaging for each cell. Raman spectra obtained from sperm cells with normal shape provide evidence that DNA in these sperm is very efficiently packaged. We find, however, that the relative protein content per cell and DNA packaging efficiencies are distributed over a relatively wide range for sperm cells with both normal and abnormal shape. These findings indicate that single cell Raman spectroscopy should be a valuable tool in assessing the quality of sperm cells for in-vitro fertilization.

  1. In vitro quantitation of human femoral artery atherosclerosis using near-infrared Raman spectroscopy (United States)

    Dykes, Ava C.; Anastasiadis, Pavlos; Allen, John S., III; Sharma, Shiv K.


    Near-infrared Raman spectroscopy has been used in vitro to identify calcified atherosclerotic plaques in human femoral arteries. Raman techniques allow for the identification of these plaques in a nondestructive manner, which may allow for the diagnosis of coronary artery disease in cardiac patients in the future. As Raman spectroscopy also reveals chemical information about the composition of the arteries, it can also be used as a prognostic tool. The in vivo detection of atherosclerotic plaques at risk for rupture in cardiac patients will enhance treatment methods while improving clinical outcomes for these procedures. Raman spectra were excited by an Invictus 785-nm NIR laser and measured with a fiber-coupled micro-Raman RXN system (Kaiser Optical Systems, Inc., Ann Arbor, MI) equipped with a 785 nm CW laser and CCD detector. Chemical mapping of arteries obtained post mortem allowed for the discrete location of atherosclerotic plaques. Raman peaks at 961 and 1073 cm-1 reveal the presence of calcium hydroxyapatite and carbonate apatite, which are known to be present in calcified plaques. By mapping the locations of these peaks the boundaries of the plaques can be precisely determined. Areas of varying degrees of calcification were also identified. Because this can be useful in determining the degree of plaque calcification and vessel stenosis, this may have a significant impact on the clinical treatment of atherosclerotic plaques in the future.

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

    Directory of Open Access Journals (Sweden)

    Zhiyun Li


    Full Text Available 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.

  3. Rapid detection of benzoyl peroxide in wheat flour by using Raman scattering spectroscopy (United States)

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


    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

  4. Matrix Effects in Quantitative Assessment of Pharmaceutical Tablets Using Transmission Raman and Near-Infrared (NIR) Spectroscopy. (United States)

    Sparén, Anders; Hartman, Madeleine; Fransson, Magnus; Johansson, Jonas; Svensson, Olof


    Raman spectroscopy can be an alternative to near-infrared spectroscopy (NIR) for nondestructive quantitative analysis of solid pharmaceutical formulations. Compared with NIR spectra, Raman spectra have much better selectivity, but subsampling was always an issue for quantitative assessment. Raman spectroscopy in transmission mode has reduced this issue, since a large volume of the sample is measured in transmission mode. The sample matrix, such as particle size of the drug substance in a tablet, may affect the Raman signal. In this work, matrix effects in transmission NIR and Raman spectroscopy were systematically investigated for a solid pharmaceutical formulation. Tablets were manufactured according to an experimental design, varying the factors particle size of the drug substance (DS), particle size of the filler, compression force, and content of drug substance. All factors were varied at two levels plus a center point, except the drug substance content, which was varied at five levels. Six tablets from each experimental point were measured with transmission NIR and Raman spectroscopy, and their concentration of DS was determined for a third of those tablets. Principal component analysis of NIR and Raman spectra showed that the drug substance content and particle size, the particle size of the filler, and the compression force affected both NIR and Raman spectra. For quantitative assessment, orthogonal partial least squares regression was applied. All factors varied in the experimental design influenced the prediction of the DS content to some extent, both for NIR and Raman spectroscopy, the particle size of the filler having the largest effect. When all matrix variations were included in the multivariate calibrations, however, good predictions of all types of tablets were obtained, both for NIR and Raman spectroscopy. The prediction error using transmission Raman spectroscopy was about 30% lower than that obtained with transmission NIR spectroscopy.

  5. Detecting alterations of glucose and lipid components in human serum by near-infrared Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    Rita de Cássia Fernandes Borges

    Full Text Available Introduction Raman spectroscopy may become a tool for the analysis of glucose and triglycerides in human serum in real time. This study aimed to detect spectral differences in lipid and glucose components of human serum, thus evaluating the feasibility of Raman spectroscopy for diagnostic purposes. Methods A total of 44 samples of blood serum were collected from volunteers and submitted for clinical blood biochemical analysis. The concentrations of glucose, cholesterol, triglycerides, and low-density and high-density lipoproteins (LDL and HDL were obtained using standard biochemical assays. Serum samples were placed in Eppendorf tubes (200 µL, kept cooled (5 °C and analyzed with near-infrared Raman spectroscopy (830 nm, 250 mW, 50 s accumulation. The mean spectra of serum with normal or altered concentrations of each parameter were compared to determine which Raman bands were related to the differences between these two groups. Results Differences in peak intensities of altered sera compared to normal ones depended on the parameter under analysis: for glucose, peaks were related to glucose; for lipid compounds the main changes occurred in the peaks related to cholesterol, lipids (mainly triolein and proteins. Principal Components Analysis discriminated altered glucose, cholesterol and triglycerides from the normal serum based on the differences in the concentration of these compounds. Conclusion Differences in the peak intensities of selected Raman bands could be seen in normal and altered blood serum samples, and may be employed as a means of diagnosis in clinical analysis.

  6. Dielectrophoretic positioning of single nanoparticles on atomic force microscope tips for tip-enhanced Raman spectroscopy. (United States)

    Leiterer, Christian; Deckert-Gaudig, Tanja; Singh, Prabha; Wirth, Janina; Deckert, Volker; Fritzsche, Wolfgang


    Tip-enhanced Raman spectroscopy, a combination of Raman spectroscopy and scanning probe microscopy, is a powerful technique to detect the vibrational fingerprint of molecules at the nanometer scale. A metal nanoparticle at the apex of an atomic force microscope tip leads to a large enhancement of the electromagnetic field when illuminated with an appropriate wavelength, resulting in an increased Raman signal. A controlled positioning of individual nanoparticles at the tip would improve the reproducibility of the probes and is quite demanding due to usually serial and labor-intensive approaches. In contrast to commonly used submicron manipulation techniques, dielectrophoresis allows a parallel and scalable production, and provides a novel approach toward reproducible and at the same time affordable tip-enhanced Raman spectroscopy tips. We demonstrate the successful positioning of an individual plasmonic nanoparticle on a commercial atomic force microscope tip by dielectrophoresis followed by experimental proof of the Raman signal enhancing capabilities of such tips. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Revealing New Structural Insights from Surfactant Micelles through DLS, Microrheology and Raman Spectroscopy

    Directory of Open Access Journals (Sweden)

    Samiul Amin


    Full Text Available The correlation between molecular changes and microstructural evolution of rheological properties has been demonstrated for the first time in a mixed anionic/zwitterionic surfactant-based wormlike micellar system. Utilizing a novel combination of DLS-microrheology and Raman Spectroscopy, the effect of electrostatic screening on these properties of anionic (SLES and zwitterionic (CapB surfactant mixtures was studied by modulating the NaCl concentration. As Raman Spectroscopy delivers information about the molecular structure and DLS-microrheology characterizes viscoelastic properties, the combination of data delivered allows for a deeper understanding of the molecular changes underlying the viscoelastic ones. The high frequency viscoelastic response obtained through DLS-microrheology has shown the persistence of the Maxwell fluid response for low viscosity solutions at high NaCl concentrations. The intensity of the Raman band at 170 cm−1 exhibits very strong correlation with the viscosity variation. As this Raman band is assigned to hydrogen bonding, its variation with NaCl concentration additionally indicates differences in water structuring due to potential microstructural differences at low and high NaCl concentrations. The microstructural differences at low and high NaCl concentrations are further corroborated by persistence of a slow mode at the higher NaCl concentrations as seen through DLS measurements. The study illustrates the utility of the combined DLS, DLS-optical microrheology and Raman Spectroscopy in providing new molecular structural insights into the self-assembly process in complex fluids.

  8. Discrimination analysis of human lung cancer cells associated with histological type and malignancy using Raman spectroscopy (United States)

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


    The Raman spectroscopic technique enables the observation of intracellular molecules without fixation or labeling procedures in situ. Raman spectroscopy is a promising technology for diagnosing cancers-especially lung cancer, one of the most common cancers in humans-and other diseases. The purpose of this study was to find an effective marker for the identification of cancer cells and their malignancy using Raman spectroscopy. We demonstrate a classification of cultured human lung cancer cells using Raman spectroscopy, principal component analysis (PCA), and linear discrimination analysis (LDA). Raman spectra of single, normal lung cells, along with four cancer cells with different pathological types, were successfully obtained with an excitation laser at 532 nm. The strong appearance of bands due to cytochrome c (cyt-c) indicates that spectra are resonant and enhanced via the Q-band near 550 nm with excitation light. The PCA loading plot suggests a large contribution of cyt-c in discriminating normal cells from cancer cells. The PCA results reflect the nature of the original cancer, such as its histological type and malignancy. The five cells were successfully discriminated by the LDA.

  9. Raman spectroscopy as a PAT for pharmaceutical blending: Advantages and disadvantages. (United States)

    Riolo, Daniela; Piazza, Alessandro; Cottini, Ciro; Serafini, Margherita; Lutero, Emilio; Cuoghi, Erika; Gasparini, Lorena; Botturi, Debora; Marino, Iari Gabriel; Aliatis, Irene; Bersani, Danilo; Lottici, Pier Paolo


    Raman spectroscopy has been positively evaluated as a tool for the in-line and real-time monitoring of powder blending processes and it has been proved to be effective in the determination of the endpoint of the mixing, showing its potential role as process analytical technology (PAT). The aim of this study is to show advantages and disadvantages of Raman spectroscopy with respect to the most traditional HPLC analysis. The spectroscopic results, obtained directly on raw powders, sampled from a two-axis blender in real case conditions, were compared with the chromatographic data obtained on the same samples. The formulation blend used for the experiment consists of active pharmaceutical ingredient (API, concentrations 6.0% and 0.5%), lactose and magnesium stearate (as excipients). The first step of the monitoring process was selecting the appropriate wavenumber region where the Raman signal of API is maximal and interference from the spectral features of excipients is minimal. Blend profiles were created by plotting the area ratios of the Raman peak of API (A API ) at 1598cm -1 and the Raman bands of excipients (A EXC ), in the spectral range between 1560 and 1630cm -1 , as a function of mixing time: the API content can be considered homogeneous when the time-dependent dispersion of the area ratio is minimized. In order to achieve a representative sampling with Raman spectroscopy, each sample was mapped in a motorized XY stage by a defocused laser beam of a micro-Raman apparatus. Good correlation between the two techniques has been found only for the composition at 6.0% (w/w). However, standard deviation analysis, applied to both HPLC and Raman data, showed that Raman results are more substantial than HPLC ones, since Raman spectroscopy enables generating data rich blend profiles. In addition, the relative standard deviation calculated from a single map (30 points) turned out to be representative of the degree of homogeneity for that blend time. Copyright © 2017

  10. Raman-laser spectroscopy of Wannier-Stark states

    International Nuclear Information System (INIS)

    Tackmann, G.; Pelle, B.; Hilico, A.; Beaufils, Q.; Pereira dos Santos, F.


    Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow one-dimensional (1D) vertical lattice. For sufficiently long laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atomic external degrees of freedom.

  11. Determination of Young's Modulus of Graphene by Raman Spectroscopy (United States)

    Lee, Jae-Ung; Yoon, Duhee; Cheong, Hyeonsik


    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.

  12. Detection of explosives based on surface-enhanced Raman spectroscopy. (United States)

    Wackerbarth, Hainer; Salb, Christian; Gundrum, Lars; Niederkrüger, Matthias; Christou, Konstantin; Beushausen, Volker; Viöl, Wolfgang


    In this study we present a device based on surface-enhanced Raman scattering (SERS) for the detection of airborne explosives. The explosives are resublimated on a cooled nanostructured gold substrate. The explosives trinitrotoluene (TNT) and triacetone triperoxide (TATP) are used. The SERS spectrum of the explosives is analyzed. Thus, TNT is deposited from an acetonitrile solution on the gold substrate. In the case of TATP, first the bulk TATP Raman spectrum was recorded and compared with the SERS spectrum, generated by deposition out of the gas phase. The frequencies of the SERS spectrum are hardly shifted compared to the spectrum of bulk TATP. The influence of the nanostructured gold substrate temperature on the signals of TATP was studied. A decrease in temperature up to 200 K increased the intensities of the TATP bands in the SERS spectrum; below 200 K, the TATP fingerprint disappeared.

  13. Raman-laser spectroscopy of Wannier-Stark states (United States)

    Tackmann, G.; Pelle, B.; Hilico, A.; Beaufils, Q.; Pereira Dos Santos, F.


    Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow one-dimensional (1D) vertical lattice. For sufficiently long laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atomic external degrees of freedom.

  14. Raman-laser spectroscopy of Wannier-Stark states

    Energy Technology Data Exchange (ETDEWEB)

    Tackmann, G.; Pelle, B.; Hilico, A.; Beaufils, Q.; Pereira dos Santos, F. [LNE-SYRTE, UMR 8630 CNRS, Observatoire de Paris, UPMC, 61 avenue de l' Observatoire, F-75014 Paris (France)


    Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow one-dimensional (1D) vertical lattice. For sufficiently long laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atomic external degrees of freedom.

  15. High precision stress measurements in semiconductor structures by Raman microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uhlig, Benjamin


    Stress in silicon structures plays an essential role in modern semiconductor technology. This stress has to be measured and due to the ongoing miniaturization in today's semiconductor industry, the measuring method has to meet certain requirements. The present thesis deals with the question how Raman spectroscopy can be used to measure the state of stress in semiconductor structures. In the first chapter the relation between Raman peakshift and stress in the material is explained. It is shown that detailed stress maps with a spatial resolution close to the diffraction limit can be obtained in structured semiconductor samples. Furthermore a novel procedure, the so called Stokes-AntiStokes-Difference method is introduced. With this method, topography, tool or drift effects can be distinguished from stress related influences in the sample. In the next chapter Tip-enhanced Raman Scattering (TERS) and its application for an improvement in lateral resolution is discussed. For this, a study is presented, which shows the influence of metal particles on the intensity and localization of the Raman signal. A method to attach metal particles to scannable tips is successfully applied. First TERS scans are shown and their impact on and challenges for high resolution stress measurements on semiconductor structures is explained. (orig.)

  16. Fiber-optic Raman spectroscopy for in vivo diagnosis of gastric dysplasia. (United States)

    Wang, Jianfeng; Lin, Kan; Zheng, Wei; Ho, Khek Yu; Teh, Ming; Yeoh, Khay Guan; Huang, Zhiwei


    This study aims to assess the clinical utility of a rapid fiber-optic Raman spectroscopy technique developed for enhancing in vivo diagnosis of gastric precancer during endoscopic examination. We have developed a real-time fiber-optic Raman spectroscopy system capable of simultaneously acquiring both fingerprint (FP) (i.e., 800-1800 cm(-1)) and high-wavenumber (HW) (i.e., 2800-3600 cm(-1)) Raman spectra from gastric tissue in vivo at endoscopy. A total of 5792 high-quality in vivo FP/HW Raman spectra (normal (n = 5160); dysplasia (n = 155), and adenocarcinoma (n = 477)) were acquired in real-time from 441 tissue sites (normal (n = 396); dysplasia (n = 11), and adenocarcinoma (n = 34)) of 191 gastric patients (normal (n = 172); dysplasia (n = 6), and adenocarcinoma (n = 13)) undergoing routine endoscopic examinations. Partial least squares discriminant analysis (PLS-DA) together with leave-one-patient-out cross validation (LOPCV) were implemented to develop robust spectral diagnostic models. The FP/HW Raman spectra differ significantly between normal, dysplasia and adenocarcinoma of the stomach, which can be attributed to changes in proteins, lipids, nucleic acids, and the bound water content. PLS-DA and LOPCV show that the fiber-optic FP/HW Raman spectroscopy provides diagnostic sensitivities of 96.0%, 81.8% and 88.2%, and specificities of 86.7%, 95.3% and 95.6%, respectively, for the classification of normal, dysplastic and cancerous gastric tissue, superior to either the FP or HW Raman techniques alone. Further dichotomous PLS-DA analysis yields a sensitivity of 90.9% (10/11) and specificity of 95.9% (380/396) for the detection of gastric dysplasia using FP/HW Raman spectroscopy, substantiating its clinical advantages over white light reflectance endoscopy (sensitivity: 90.9% (10/11), and specificity: 51.0% (202/396)). This work demonstrates that the fiber-optic FP/HW Raman spectroscopy technique has great promise for enhancing in vivo diagnosis of gastric

  17. Methodology of mycobacteria tuberculosis bacteria detection by Raman spectroscopy (United States)

    Zyubin, A.; Lavrova, A.; Manicheva, O.; Dogonadze, M.; Tsibulnikova, A.; Samusev, I.


    We have developed a methodology for the study of deactivated strains of Mycobacterium tuberculosis. Strains of the Beijing species obtained from pulmonary patient secrete (XDR strain) and reference strain (H37Rv) were investigated by Raman spectrometry with He-Ne (632,8 nm) laser excitation source. As a result of the research, the optimal experimental parameters have been obtained to get spectra of mycolic acids, which are part of the cell wall of mycobacteria.

  18. Raman spectroscopy of organic-inorganic halide perovskites

    Czech Academy of Sciences Publication Activity Database

    Ledinský, Martin; Löper, P.; Niesen, B.; Holovský, Jakub; Moon, S.J.; Yum, J. H.; De Wolf, S.; Fejfar, Antonín; Ballif, C.


    Roč. 6, č. 3 (2015), 401-406 ISSN 1948-7185 R&D Projects: GA ČR GA14-15357S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : mixed iodide and bromide lead perovskites * micro-Raman mapping * local chemical sensitivity * moisture-induced degradation * lead iodide * photoluminesce Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 8.539, year: 2015

  19. Characterization of mixed phase silicon by Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Ledinský, Martin; Fekete, Ladislav; Stuchlík, Jiří; Mates, Tomáš; Fejfar, Antonín; Kočka, Jan


    Roč. 352, - (2006), s. 1209-1212 ISSN 0022-3093 R&D Projects: GA MŽP(CZ) SM/300/1/03; GA MŽP(CZ) SN/3/172/05; GA ČR GD202/05/H003 Institutional research plan: CEZ:AV0Z10100521 Keywords : silicon Raman scattering * atomic force and scanning tunneling microscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.362, year: 2006

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

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  1. Near-infrared Raman spectroscopy using a diode laser and CCD detector for tissue diagnostics

    International Nuclear Information System (INIS)

    Gustafsson, U.


    This paper surveys the possibility to observe high-quality NIR Raman spectra of both fluorescent and non-fluorescent samples with the use of a diode laser, a fibre optic sample, a single spectrometer and a charge-coupled device (CCD) detector. A shifted excitation difference technique was implemented for removing the broad-band fluorescence emission from Raman spectra of the highly fluorescent samples. Raman spectra of 1.4-dioxane, toluene, rhodamine 6G, and HITCI in the 640 to 1840 cm -1 spectral region and 1.4-dioxane and toluene in the 400 to 3400 cm -1 spectral region have been recorded. The results open the field of sensitive tissue characterisation and the possibility of optical biopsy in vivo by using NIR Raman spectroscopy with fibre optic sampling, a single spectrometer, and a CCD detector

  2. Detection and characterization of chemical aerosol using laser-trapping single-particle Raman spectroscopy. (United States)

    Kalume, Aimable; Beresnev, Leonid A; Santarpia, Joshua; Pan, Yong-Le


    Detection and characterization of the presence of chemical agent aerosols in various complex atmospheric environments is an essential defense mission. Raman spectroscopy has the ability to identify chemical molecules, but there are limited numbers of photons detectable from single airborne aerosol particles as they are flowing through a detection system. In this paper, we report on a single-particle Raman spectrometer system that can measure strong spontaneous, stimulated, and resonance Raman spectral peaks from a single laser-trapped chemical aerosol particle, such as a droplet of the VX nerve agent chemical simulant diethyl phthalate. Using this system, time-resolved Raman spectra and elastic scattered intensities were recorded to monitor the chemical properties and size variation of the trapped particle. Such a system supplies a new approach for the detection and characterization of single airborne chemical aerosol particles.

  3. Cell identification using Raman spectroscopy in combination with optical trapping and microfluidics (United States)

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


    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.

  4. Monosodium glutamate in its anhydrous and monohydrate form: Differentiation by Raman spectroscopies and density functional calculations (United States)

    Peica, N.; Lehene, C.; Leopold, N.; Schlücker, S.; Kiefer, W.


    Monosodium glutamate (MSG), a common flavor enhancer, is detected in aqueous solutions by Raman and surface-enhanced Raman (SERS) spectroscopies at the micromolar level. The presence of different species, such as protonated and unprotonated MSG, is demonstrated by concentration and pH dependent Raman and SERS experiments. In particular, the symmetric bending modes of the amino group and the stretching modes of the carboxy moiety are employed as marker bands. The protonation of the NH 2 group at acidic pH values, for example, is detected in the Raman spectra. From the measured SERS spectra, a strong chemical interaction of MSG with the colloidal particles is deduced and a geometry of MSG adsorbed on the silver surface is proposed. In order to assign the observed Raman bands, calculations employing density functional theory (DFT) were performed. The calculated geometries, harmonic vibrational wavenumbers and Raman scattering activities for both MSG forms are in good agreement with experimental data. The set of theoretical data enables a complete vibrational assignment of the experimentally detected Raman spectra and the differentiation between the anhydrous and monohydrate forms of MSG.

  5. Normal Raman and SERS spectroscopy of the vitamin E

    Energy Technology Data Exchange (ETDEWEB)

    Cai Tiantian; Gu Huaimin; Yuan Xiaojuan; Liu Fangfang, E-mail: [MOE Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, 510631, Guangzhou (China)


    In this study, surface-enhanced Raman scattering(SERS)spectra of vitamin E were obtained on colloidal silver(Ag). Alpha-(-) tocopherol which is the only form that is recognized to meet human requirements was selected to study. The analytes ({+-})- -tocopherol were dissolved in chloroform (CHCl{sub 3}) and the silver colloid was poured into the compound. Silver colloid was reduced by hydroxylamine hydrochloride. The analytes were the supernatant after standing the mixture for the reason that chloroform have no signals in surface-enhanced Raman scattering in the Ag colloid, and it would not affect the determination of the ({+-})- -tocopherol. The Normal Raman and SERS spectrum of Vitamin E were contrastively studied to realize how the vitamin E stuck to the silver nanoparticles. The results show the fat-soluble substances can be analysed by SERS. The spectra indicate that the molecules are adsorbed on the surface through the COO- groups by the simultaneous involvement of a and -type coordination. These results suggest some important criteria for consideration in SERS measurements and also provide important insights into the problem of predicting SERS activities for different fat-soluble substances.

  6. Characterization of acetaminophen: molecular microanalysis with Raman microprobe spectroscopy. (United States)

    Pestaner, J P; Mullick, F G; Centeno, J A


    The in situ spectroscopic identification of acetaminophen in a fatal overdose case is described. Numerous techniques have been used to analyze acetaminophen in biological fluids, however, the use of nondestructive spectroscopic techniques has not been documented. In this investigation, the demonstration of the drug material was established by using the laser Raman microprobe technique, providing an accurate identification by virtue of the drug's molecular fingerprint characteristics. Material found on the deceased was collected and placed on metal (aluminum-coated) plated slides and excited with the 514.5 nm line of an argon ion laser, which was focused to a 1 micron spot size using a high-resolution optical microscope. Spectra of acetaminophen particles with an average size of 5 to 8 microns were obtained. The Raman spectrum of this drug contains characteristic group frequencies assigned to the C = O at 1649 cm-1, the N-H deformation mode at 1620 to 1612 cm-1, the bendstretch mode of the H-N-C = O at 1562 cm-1, the C-H bending mode at 1325 cm-1, and the phenyl ring stretch at 799 cm-1, respectively. The results reported here demonstrate the capability of laser Raman microprobe as a useful adjunct tool for the identification of foreign materials in forensic pathology.

  7. Probing anisotropic magnetotransport in manganese perovskites using Raman spectroscopy

    International Nuclear Information System (INIS)

    Liu, H.L.; Yoon, S.; Cooper, S.L.; Cheong, S.; Han, P.D.; Payne, D.A.


    We report an electronic Raman scattering study of the colossal magnetoresistance (CMR) manganese perovskites as a function of temperature, magnetic field, symmetry, and doping. The low-frequency electronic Raman spectrum in the paramagnetic-insulating phase of these materials is characterized by a diffusive Raman-scattering response, while a nearly flat continuum response is observed in the ferromagnetic-metallic state. We found that the B 1g -symmetry electronic scattering intensity is significantly reduced with applied magnetic field near T C , in a manner reminiscent of the dc magnetoresistivity. The strongly field-dependent scattering rate in the B 1g channel appears to reflect the highly field-dependent mobility along the Mn-O bond direction expected in the double exchange mechanism. In addition, we observe a persistent field dependence in the B 1g electronic scattering response for T C , suggesting that the ferromagnetic phase is inhomogeneous, perhaps consisting of both metallic and insulating components. copyright 1998 The American Physical Society

  8. Profilometry of thin films on rough substrates by Raman spectroscopy

    KAUST Repository

    Ledinský, Martin


    Thin, light-absorbing films attenuate the Raman signal of underlying substrates. In this article, we exploit this phenomenon to develop a contactless thickness profiling method for thin films deposited on rough substrates. We demonstrate this technique by probing profiles of thin amorphous silicon stripes deposited on rough crystalline silicon surfaces, which is a structure exploited in high-efficiency silicon heterojunction solar cells. Our spatially-resolved Raman measurements enable the thickness mapping of amorphous silicon over the whole active area of test solar cells with very high precision; the thickness detection limit is well below 1 nm and the spatial resolution is down to 500 nm, limited only by the optical resolution. We also discuss the wider applicability of this technique for the characterization of thin layers prepared on Raman/photoluminescence-active substrates, as well as its use for single-layer counting in multilayer 2D materials such as graphene, MoS2 and WS2.

  9. Fourier-Transform Raman Spectroscopy of Polymers Caractérisation de polymères par spectroscopie Raman à transformée de Fourier

    Directory of Open Access Journals (Sweden)

    Siesler H. W.


    Full Text Available The recent extension of the Fourier-Transform (FT technique to the Raman effect has launched Raman spectroscopy into a new era of polymer chemical and physical applications. Thus, the increase in signal-to-noise ratio and the improvement in time resolution have largely enhanced the potential of FT-Raman spectroscopy for analytical applications, the characterization of time-dependent phenomena and the on-line combination with other techniques. Primarily the suppression of fluorescence by shifting the excitation line to the near-infrared (NIR region has contributed to the fast acceptance as an industrial routine tool. Furthermore, the application of fiber optics has opened up the areas of process-control and remote sensing. Les applications de la spectroscopie Raman dans le domaine des polymères sont entrées dans une ère nouvelle, grâce aux récents développements de la technique à transformée de Fourier avec excitation dans le proche infrarouge. L'augmentation du rapport signal sur bruit et l'amélioration de la résolution temporelle ont fortement renforcé les potentialités de la technique en ce qui concerne les applications analytiques, la caractérisation de phénomènes qui dépendent du temps et le couplage en ligne avec d'autres techniques. La suppression du phénomène de fluorescence par déplacement de la longueur d'onde de l'excitatrice dans le proche infrarouge a contribué à l'intégration rapide de l'outil en site industriel. L'emploi de fibres optiques a permis l'accroissement des applications dans le domaine du contrôle des procédés et d'analyser à distance.

  10. Structural changes of human RNase L upon homodimerization investigated by Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Kříž, M.; Snášel, Jan; Kopecký, V. Jr.; Páv, Ondřej; Rosenberg, Ivan; Štepánek, J.


    Roč. 1824, č. 9 (2012), s. 1039-1044 ISSN 1570-9639 R&D Projects: GA ČR GA202/09/0193; GA AV ČR KAN200520801 Grant - others:GA AV ČR(CZ) KJB101120805 Program:KJ Institutional support: RVO:61388963 Keywords : RNase L * Raman spectroscopy * DCDR spectroscopy * phosphonate oligoadenylate * ligand binding Subject RIV: BO - Biophysics Impact factor: 3.733, year: 2012

  11. Non-invasive blood glucose monitoring with Raman spectroscopy: prospects for device miniaturization

    International Nuclear Information System (INIS)

    Wróbel, M.S.


    The number of patients with diabetes has reached over 350 million, and still continues to increase. The need for regular blood glucose monitoring sparks the interest in the development of modern detection technologies. One of those methods, which allows for noninvasive measurements, is Raman spectroscopy. The ability of infrared light to penetrate deep into tissues allows for obtaining measurements through the skin without its perforation. This paper presents the limitations and possibilities of non-invasive blood glucose monitoring with Raman spectroscopy. Especially focusing on the possibilities for device miniaturization. Such device incorporates a Raman spectrometer, a fiber-optical probe, and a computing device (microcontroller, smartphone, etc.) which calculates the glucose concentration using specialized algorithms. Simplification of device design, as well as turbidity correction technique and a new proposed method of synchronized detection are described

  12. Discrimination of inflammatory bowel disease using Raman spectroscopy and linear discriminant analysis methods (United States)

    Ding, Hao; Cao, Ming; DuPont, Andrew W.; Scott, Larry D.; Guha, Sushovan; Singhal, Shashideep; Younes, Mamoun; Pence, Isaac; Herline, Alan; Schwartz, David; Xu, Hua; Mahadevan-Jansen, Anita; Bi, Xiaohong


    Inflammatory bowel disease (IBD) is an idiopathic disease that is typically characterized by chronic inflammation of the gastrointestinal tract. Recently much effort has been devoted to the development of novel diagnostic tools that can assist physicians for fast, accurate, and automated diagnosis of the disease. Previous research based on Raman spectroscopy has shown promising results in differentiating IBD patients from normal screening cases. In the current study, we examined IBD patients in vivo through a colonoscope-coupled Raman system. Optical diagnosis for IBD discrimination was conducted based on full-range spectra using multivariate statistical methods. Further, we incorporated several feature selection methods in machine learning into the classification model. The diagnostic performance for disease differentiation was significantly improved after feature selection. Our results showed that improved IBD diagnosis can be achieved using Raman spectroscopy in combination with multivariate analysis and feature selection.

  13. Application of infrared reflection and Raman spectroscopy for quantitative determination of fat in potato chips (United States)

    Mazurek, Sylwester; Szostak, Roman; Kita, Agnieszka


    Potato chips are important products in the snack industry. The most significant parameter monitored during their quality control process is fat content. The Soxhlet method, which is applied for this purpose, is time consuming and expensive. We demonstrate that both infrared and Raman spectroscopy can effectively replace the extraction method. Raman, mid-infrared (MIR) and near-infrared (NIR) spectra of the homogenised laboratory-prepared chips were recorded. On the basis of obtained spectra, partial least squares (PLS) calibration models were constructed. They were characterised by the values of relative standard errors of prediction (RSEP) in the 1.0-1.9% range for both calibration and validation data sets. Using the developed models, six commercial products were successfully quantified with recovery in the 98.5-102.3% range against the AOAC extraction method. The proposed method for fat quantification in potato chips based on Raman spectroscopy can be easily adopted for on-line product analysis.

  14. A study of Raman spectroscopy for the early detection and classification of malignancy in oesophageal tissue

    CERN Document Server

    Kendall, C A


    Raman Spectroscopy for the identification and classification of malignancy in the oesophagus has been demonstrated in this thesis. The potential of Raman spectroscopy in this field is twofold; as an adjunct for the pathologist and as a biopsy targeting tool at endoscopy. This study has demonstrated the feasibility of these potential applications in vitro. Spectral diagnostic models have been developed by correlating spectral information with histopathology. This is the current 'gold standard' diagnostic method for the identification of dysplasia, the established risk factor for the development of oesophageal cancer. Histopathology is a subjective assessment and widely acknowledged to have limitations. A more rigorous gold standard was therefore developed, as part of this study, using the consensus opinion of three independent expert pathologists to train the diagnostic models. Raman spectra have been measured from oesophageal tissue covering the full spectrum of malignant disease in the oesophagus, using a ne...

  15. Fast differentiation of SIRS and sepsis from blood plasma of ICU patients using Raman spectroscopy. (United States)

    Neugebauer, Ute; Trenkmann, Sabine; Bocklitz, Thomas; Schmerler, Diana; Kiehntopf, Michael; Popp, Jürgen


    Currently, there is no biomarker that can reliable distinguish between infectious and non-infectious systemic inflammatory response syndrome (SIRS). However, such a biomarker would be of utmost importance for early identification and stratification of patients at risk to initiate timely and appropriate antibiotic treatment. Within this proof of principle study, the high potential of Raman spectroscopy for the fast differentiation of non-infectious SIRS and sepsis is demonstrated. Blood plasma collected from 70 patients from the intensive care unit (31 patients with sepsis and 39 patients classified with SIRS without infection) was analyzed by means of Raman spectroscopy. A PCA-LDA based classification model was trained with Raman spectra from test samples and yielded for sepsis a sensitivity of 1.0 and specificity of 0.82. These results have been confirmed with an independent dataset (prediction accuracy 80%). Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Investigation of germanium implanted with aluminum by multi-laser micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sanson, A., E-mail: [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Napolitani, E. [MATIS IMM-CNR at Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Impellizzeri, G. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Giarola, M. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); De Salvador, D. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy); Privitera, V.; Priolo, F. [MATIS IMM-CNR and Dipartimento di Fisica e Astronomia, Università di Catania, Via S. Sofia 64, I-95123 Catania (Italy); Mariotto, G. [Dipartimento di Informatica, Università di Verona, Strada le Grazie 15, I-37134 Verona (Italy); Carnera, A. [Dipartimento di Fisica e Astronomia, Università di Padova, Via Marzolo 8, I-35131 Padova (Italy)


    Germanium samples, implanted with aluminum and annealed, have been investigated by micro-Raman spectroscopy using different excitation lines with the aim of gaining insights about the Al distribution at different depths beneath the sample surface and to correlate the Raman spectra with the electrical and chemical profiles, obtained by Spreading Resistance Profiling (SRP) and Secondary Ions Mass Spectrometry (SIMS) measurements, respectively. The intensity of the Al–Ge Raman peak at about 370 cm{sup −1}, due to the local vibrational mode of the substitutional Al atoms in the Ge matrix, has been directly related to the SRP behavior, while no correlation has been observed with SIMS profiles. These findings show that the electrically active content is entirely due to the substitutional Al atoms. Finally, a clear down shift is observed for the Ge–Ge Raman peak at ∼ 300 cm{sup −1}, which also seems to be directly related to the active content of Al dopant atoms. This work shows that micro-Raman spectroscopy can be a suitable tool for the study of doping profiles in Ge. - Highlights: ► Al-implanted Ge and annealed were studied by micro-Raman spectroscopy. ► Using different laser lines we have investigated the implants at different depths. ► The Al–Ge Raman peak at about 370 cm{sup −1} is directly related to the SRP behavior. ► The electrically active content is entirely due to the substitutional Al atoms. ► Carrier effects are observed on the Ge–Ge peak at ∼ 300 cm{sup −1}.

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

    Anwar, Shahzad; Firdous, Shamaraz


    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.

  18. Direct measurement of phase coexistence in DPPC/Cholesterol vesicles using Raman spectroscopy.

    NARCIS (Netherlands)

    de Lange, M.J.L.; Bonn, M.; Müller, M.


    The phase behavior of bilayers of binary mixtures of 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol has been studied using Raman spectroscopy. It is observed that the shape of the cholesterol vibrational spectrum in lipid-cholesterol binary mixtures does not vary significantly

  19. Following the Mechanisms of Bacteriostatic versus Bactericidal Action Using Raman Spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Bernatová, Silvie; Samek, Ota; Pilát, Zdeněk; Šerý, Mojmír; Ježek, Jan; Jákl, Petr; Šiler, Martin; Krzyžánek, Vladislav; Zemánek, Pavel; Holá, V.; Dvořáčková, M.; Růžička, F.


    Roč. 18, č. 11 (2013), s. 13188-13199 ISSN 1420-3049 R&D Projects: GA MŠk ED0017/01/01; GA ČR GAP205/11/1687 Institutional support: RVO:68081731 Keywords : Raman spectroscopy * antibiotics * bacteria * bactericidal * bacteriostatic Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 2.095, year: 2013

  20. Achievements in resonance Raman spectroscopy review of a technique with a distinct analytical chemistry potential

    NARCIS (Netherlands)

    Efremov, E.V.; Ariese, F.; Gooijer, C.


    In an extended introduction, key aspects of resonance Raman spectroscopy (RRS) such as enhanced sensitivity and selectivity are briefly discussed in comparison with normal RS. The analytical potential is outlined. Then achievements in different fields of research are highlighted in four sections,

  1. Review of multidimensional data processing approaches for Raman and infrared spectroscopy

    NARCIS (Netherlands)

    Gautam, R.; Vanga, S.; Ariese, F.


    Raman and Infrared (IR) spectroscopies provide information about the structure, functional groups and environment of the molecules in the sample. In combination with a microscope, these techniques can also be used to study molecular distributions in heterogeneous samples. Over the past few decades

  2. 3D plasmonic nanostructures as building blocks for ultrasensitive Raman spectroscopy

    KAUST Repository

    Toma, Andrea


    The fabrication of complex 3D plasmonic nanostructures opens new scenarios towards the realization of high electric field confinement and enhancement. We exploit the unique properties of these nanostructures for performing Raman spectroscopy in the single/few molecules detection limit. © 2014 OSA.

  3. Raman spectroscopy and spectroelectrochemistry of the chemically n-doped DWCNT

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Kavan, Ladislav; Zukalová, Markéta; Dunsch, L.


    Roč. 244, č. 11 (2007), s. 4086-4091 ISSN 0370-1972 R&D Projects: GA AV ČR KJB400400601; GA MŠk LC510 Institutional research plan: CEZ:AV0Z40400503 Keywords : Raman spectroscopy * spectroelectrochemistry * DWCNT Subject RIV: CG - Electrochemistry Impact factor: 1.071, year: 2007

  4. Continuous Flow-Resonance Raman Spectroscopy of an Intermediate Redox State of Cytochrome-C

    DEFF Research Database (Denmark)

    Forster, M.; Hester, R. E.; Cartling, B.


    An intermediate redox state of cytochrome c at alkaline pH, generated upon rapid reduction by sodium dithionite, has been observed by resonance Raman (RR) spectroscopy in combination with the continuous flow technique. The RR spectrum of the intermediate state is reported for excitation both...

  5. ZnO-based semiconductors studied by Raman spectroscopy: semimagnetic alloying, doping, and nanostructures


    Schumm, Marcel


    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles).

  6. Nanostructure design for surface-enhanced Raman spectroscopy - prospects and limits

    DEFF Research Database (Denmark)

    Xiao, Sanshui; Mortensen, Niels Asger; Jauho, Antti-Pekka


    Surface-enhanced Raman spectroscopy (SERS) allows single-molecule detection due to the strong field localization occurring at sharp bends or kinks of the metal-vacuum interface. An important question concerns the limits of the signal enhancement that can be achieved via a judicious design...

  7. Microanalysis of clay-based pigments in painted artworks by the means of Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Košařová, V.; Hradil, David; Němec, I.; Bezdička, Petr; Kanický, V.


    Roč. 44, č. 11 (2013), s. 1570-1577 ISSN 0377-0486 Institutional support: RVO:61388980 Keywords : Raman spectroscopy * clay-based pigments * clay minerals * iron oxides * microanalysis of paintings Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.519, year: 2013

  8. A spatially offset Raman spectroscopy method for non-destructive detection of gelatin-encapsulated powders (United States)

    Non-destructive subsurface detection of encapsulated, coated, or seal-packaged foods and pharmaceuticals can help prevent distribution and consumption of counterfeit or hazardous products. This study used a Spatially Offset Raman Spectroscopy (SORS) method to detect and identify urea, ibuprofen, and...

  9. Raman Spectroscopy of Conformational Changes in Membrane-Bound Sodium Potassium ATPase

    DEFF Research Database (Denmark)

    Helix Nielsen, Claus; Abdali, Salim; Lundbæk, Jens August


    In this investigation we assess the potential of Raman spectroscopy as a tool for probing conformational changes in membrane-spanning proteins — in this case, the sodium potassium adenosine triphosphatase (Na+,K+-ATPase). Spectral analysis of protein-lipid complexes is complicated by the presence...

  10. Raman spectroscopy, ab-initio model calculations, and conformational, equilibria in ionic liquids

    DEFF Research Database (Denmark)

    Berg, Rolf W.


    .........318 12.7 Other studies on [CnC1Im]+ liquids ... 329 12.8 Conformations equilibria in liquids versus temperature .... 332 12.9 Local structures in ionic liquids .....335 12.10 Other systems .................338 12.11 Other applications of Raman spectroscopy .................346 12.12 Conclusions...

  11. The effect of a thin gold layer on graphene: a Raman spectroscopy study

    Czech Academy of Sciences Publication Activity Database

    Kalbáč, Martin; Valeš, Václav; Vejpravová, Jana


    Roč. 4, č. 105 (2014), s. 60929-60935 ISSN 2046-2069 R&D Projects: GA MŠk LL1301; GA ČR GAP204/10/1677 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : chemical vapor deposition * graphene * Raman spectroscopy Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.840, year: 2014

  12. Infrared and Raman Spectroscopy: A Discovery-Based Activity for the General Chemistry Curriculum (United States)

    Borgsmiller, Karen L.; O'Connell, Dylan J.; Klauenberg, Kathryn M.; Wilson, Peter M.; Stromberg, Christopher J.


    A discovery-based method is described for incorporating the concepts of IR and Raman spectroscopy into the general chemistry curriculum. Students use three sets of springs to model the properties of single, double, and triple covalent bonds. Then, Gaussian 03W molecular modeling software is used to illustrate the relationship between bond…

  13. Chapter 1.1 Crystallinity of Nanocellulose Materials by Near-IR FT-Raman Spectroscopy (United States)

    Umesh P. Agarwal; Richard S. Reiner; Sally A. Ralph


    Considering that crystallinity is one of the important properties that influence the end use of cellulose nanomaterials, it is important that the former be measured accurately. Recently, a new method based on near-IR FTRaman spectroscopy was proposed to determine cellulose I crystallinity. It was reported that in the Raman spectrum of cellulose materials, the...

  14. Surface-enhanced resonance Raman spectroscopy as an identification tool in column liquid chromatography

    NARCIS (Netherlands)

    Seifar, R.M.; Altelaar, M.A.F.; Dijkstra, R.J.; Ariese, F.; Brinkman, U.A.T.; Gooijer, C.


    The compatibility of ion-pair reversed-phase column liquid chromatography and surface-enhanced resonance Raman spectroscopy (SERRS) for separation and identification of anionic dyes has been investigated, with emphasis on the at-line coupling via a thin-layer chromatography (TLC) plate. SERR spectra

  15. Detection of Occupancy Differences in Methane Gas Hydrates by Raman Spectroscopy

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.; Stenby, Erling Halfdan


    of reservoir fluids due to plugging. Methods to prevent hydrate formation are in use, e.g. by injection of inhibitors. From environmental and security points of view an easy way to detect hydrate formation is of interest. We have tried to detect methane hydrate formation by use of Raman spectroscopy....

  16. Raman spectroscopy-based detection of chemical contaminants in food powders (United States)

    Raman spectroscopy technique has proven to be a reliable method for qualitative detection of chemical contaminants in food ingredients and products. For quantitative imaging-based detection, each contaminant particle in a food sample must be detected and it is important to determine the necessary sp...

  17. Mathematical model for biomolecular quantification using surface-enhanced Raman spectroscopy based signal intensity distributions

    DEFF Research Database (Denmark)

    Palla, Mirko; Bosco, Filippo Giacomo; Yang, Jaeyoung


    This paper presents the development of a novel statistical method for quantifying trace amounts of biomolecules by surface-enhanced Raman spectroscopy (SERS) using a rigorous, single molecule (SM) theory based mathematical derivation. Our quantification framework could be generalized for planar...

  18. Role of hydration in the phase transition of polypeptides investigated by NMR and Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Dybal, Jiří; Schmidt, Pavel; Kříž, Jaroslav; Kurková, Dana; Rodriguez-Cabello, J. C.; Alonso, M.


    Roč. 205, - (2004), s. 143-150 ISSN 1022-1360 R&D Projects: GA AV ČR IAA4050208 Institutional research plan: CEZ:AV0Z4050913 Keywords : NMR * quantum chemistry * Raman spectroscopy Subject RIV: CD - Macromolecular Chemistry Impact factor: 0.691, year: 2004

  19. ZnO-based semiconductors studied by Raman spectroscopy. Semimagnetic alloying, doping, and nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schumm, Marcel


    ZnO-based semiconductors were studied by Raman spectroscopy and complementary methods (e.g. XRD, EPS) with focus on semimagnetic alloying with transition metal ions, doping (especially p-type doping with nitrogen as acceptor), and nanostructures (especially wet-chemically synthesized nanoparticles). (orig.)

  20. Raman spectroscopy and multivariate analysis for the non invasive diagnosis of clinically inconclusive vulval lichen sclerosus. (United States)

    Frost, Jonathan; Ludeman, Linmarie; Hillaby, Kathryn; Gornall, Robert; Lloyd, Gavin; Kendall, Catherine; Shore, Angela C; Stone, Nick


    Vulval lichen sclerosus (LS) is a common inflammatory condition associated with an increased risk of developing vulval carcinoma. Diagnosis is usually clinical although biopsy is necessary if the diagnosis is uncertain or if there is a failure to respond to adequate initial treatment. Raman spectroscopy has the potential to be applied in vivo for near real time objective non-invasive optical diagnosis, avoiding the need for invasive tissue biopsies. The aim of this study was to evaluate the diagnostic performance of Raman spectroscopy for differentiating LS from other vulval conditions in fresh vulval biopsies. Biopsies were analysed from 27 women with suspected LS in whom the attending gynaecologist could not establish the diagnosis on clinical presentation alone. Spectral variance was explored using principal component analysis and in conjunction with the histological diagnoses was used to develop and test a multivariate linear discriminant classification model. This model was validated with leave one sample out cross validation and the diagnostic performance of the technique assessed in comparison with the pathology gold standard. After cross validation the technique was able to correctly differentiate LS from other inflammatory vulval conditions with a sensitivity of 91% and specificity of 80%. This study demonstrates Raman spectroscopy has potential as a technique for in vivo non-invasive diagnosis of vulval skin conditions. Applied in the clinical setting this technique may reduce the need for invasive tissue biopsy. Further in vivo study is needed to assess the ability of Raman spectroscopy to diagnose other vulval conditions before clinical application.