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Sample records for anti-stokes raman spectroscopic

  1. Spectral interferometric polarised coherent anti-Stokes Raman spectroscopy

    CERN Document Server

    Littleton, Brad; Festy, Frederic; Richards, David

    2013-01-01

    We have developed an interferometric implementation of coherent anti-Stokes Raman scattering (CARS) which enables broadband coherent Raman spectroscopy free from non-resonant background (NRB), with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response which can be directly compared to polarised spontaneous Raman spectra. The method requires only passive polarisation optics and is suitable for a wide range of laser linewidths and pulse durations

  2. Raman and coherent anti-Stokes Raman scattering microspectroscopy for biomedical applications

    Science.gov (United States)

    Krafft, Christoph; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen

    2012-04-01

    A tutorial article is presented for the use of linear and nonlinear Raman microspectroscopies in biomedical diagnostics. Coherent anti-Stokes Raman scattering (CARS) is the most frequently applied nonlinear variant of Raman spectroscopy. The basic concepts of Raman and CARS are introduced first, and subsequent biomedical applications of Raman and CARS are described. Raman microspectroscopy is applied to both in-vivo and in-vitro tissue diagnostics, and the characterization and identification of individual mammalian cells. These applications benefit from the fact that Raman spectra provide specific information on the chemical composition and molecular structure in a label-free and nondestructive manner. Combining the chemical specificity of Raman spectroscopy with the spatial resolution of an optical microscope allows recording hyperspectral images with molecular contrast. We also elaborate on interfacing Raman spectroscopic tools with other technologies such as optical tweezing, microfluidics and fiber optic probes. Thereby, we aim at presenting a guide into one exciting branch of modern biophotonics research.

  3. Noise figure and photon probability distribution in Coherent Anti-Stokes Raman Scattering (CARS)

    OpenAIRE

    Dimitropoulos, D.; Solli, D. R.; Claps, R.; Jalali, B.

    2006-01-01

    The noise figure and photon probability distribution are calculated for coherent anti-Stokes Raman scattering (CARS) where an anti-Stokes signal is converted to Stokes. We find that the minimum noise figure is ~ 3dB.

  4. Compressive coherent anti-Stokes Raman scattering holography.

    Science.gov (United States)

    Cocking, Alexander; Mehta, Nikhil; Shi, Kebin; Liu, Zhiwen

    2015-09-21

    Coherent anti-Stokes Raman scattering (CARS) holography captures both the amplitude and the phase of the anti-Stokes field generated from a sample and can thus perform single-shot, chemically selective three-dimensional imaging. We present compressive CARS holography, a numerical technique based on the concept of compressive sensing, to improve the quality of reconstructed images by leveraging sparsity in the source distribution and reducing the out-of-focus background noise. In particular, we use the two-step iterative shrinkage threshold (TwIST) algorithm with an l1 norm regularizer to iteratively retrieve images from an off axis CARS digital hologram. It is shown that the use of compressive CARS holography enhances the CARS holographic imaging technique by reducing noise and thereby effectively emulating a higher axial resolution using only a single shot hologram. PMID:26406699

  5. Imaging properties of coherent anti-Stokes Raman scattering microscope

    Institute of Scientific and Technical Information of China (English)

    Yuan Jing-He; Xiao Fan-Rong; Wang Gui-Ying; Xu Zhi-Zhan

    2005-01-01

    The coherent anti-Stokes Raman scattering (CARS) microscope with the combination of confocal and CARS techniques is a remarkable alternative for imaging chemical or biological specimens that neither fluoresce nor tolerate labelling. CARS is a nonlinear optical process, the imaging properties of CARS microscopy will be very different from the conventional confocal microscope. In this paper, the intensity distribution and the polarization property of the optical field near the focus was calculated. By using the Green function, the precise analytic solution to the wave equation of a Hertzian dipole source was obtained. We found that the intensity distributions vary considerably with the different experimental configurations and the different specimen shapes. So the conventional description of microscope (e.g. the point spread function) will fail to describe the imaging properties of the CARS microscope.

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

    International Nuclear Information System (INIS)

    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

  7. Quantitative, Comparable Coherent Anti-Stokes Raman Scattering (CARS) Spectroscopy: Correcting Errors in Phase Retrieval

    CERN Document Server

    Camp, Charles H; Cicerone, Marcus T

    2015-01-01

    Coherent anti-Stokes Raman scattering (CARS) microspectroscopy has demonstrated significant potential for biological and materials imaging. To date, however, the primary mechanism of disseminating CARS spectroscopic information is through pseudocolor imagery, which explicitly neglects a vast majority of the hyperspectral data. Furthermore, current paradigms in CARS spectral processing do not lend themselves to quantitative sample-to-sample comparability. The primary limitation stems from the need to accurately measure the so-called nonresonant background (NRB) that is used to extract the chemically-sensitive Raman information from the raw spectra. Measurement of the NRB on a pixel-by-pixel basis is a nontrivial task; thus, reference NRB from glass or water are typically utilized, resulting in error between the actual and estimated amplitude and phase. In this manuscript, we present a new methodology for extracting the Raman spectral features that significantly suppresses these errors through phase detrending ...

  8. 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.;

    2003-01-01

    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...

  9. 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.;

    2011-01-01

    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...... analysis, the nonlinear effects responsible for the spectral broadening are explained to be soliton fission processes, dispersive waves, and stimulated Raman scattering.......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 spectrum...

  10. Molecular vibrational dynamics in water studied by femtosecond coherent anti-Stokes Raman spectroscopy

    Science.gov (United States)

    Zhao, Yang; Zhang, Sheng; Zhou, Boyang; Dong, Zhiwei; Chen, Deying; Zhang, Zhonghua; Xia, Yuanqin

    2014-10-01

    We utilized femtosecond time-resolved coherent anti-Stokes Raman spectroscopy (CARS) to study the ultrafast vibrational dynamics in distilled water at room temperature. The CARS signals from the broad OH-stretching modes between 3100 cm-1 and 3700 cm-1 were obtained and analyzed. The dephasing times of four Raman modes in water were detected and compared.

  11. Single-pulse coherent anti-Stokes Raman spectroscopy via fiber Bragg grating

    Science.gov (United States)

    Oh, Seung Ryeol; Park, Joo Hyun; Kwon, Won Sik; Kim, Jin Hwan; Kim, Kyung-Soo; Lee, Jae Yong; Kim, Soohyun

    2016-03-01

    Fiber Bragg grating is used in a variety of applications. In this study, we suggest compact, cost-effective coherent anti- Stokes Raman spectroscopy which is based on the pulse shaping methods via commercialized fiber Bragg grating. The experiment is performed incorporating a commercialized femtosecond pulse laser system (MICRA, Coherent) with a 100 mm length of 780-HP fiber which is inscribed 50 mm of Bragg grating. The pump laser for coherent anti-Stokes Raman spectroscopy has a bandwidth of 90 nm and central wavelength of 815 nm with a notch shaped at 785 nm. The positive chirped pulse is compensated by chirped mirror set. We compensate almost 14000 fs2 of positive group delay dispersion for the transform-limited pulse at the sample position. The pulse duration was 15 fs with average power of 50 mW, and showed an adequate notch shape. Finally, coherent anti-Stokes Raman signals are observed using a spectrometer (Jobin Yvon Triax320 and TE-cooled Andor Newton EMCCD). We obtained coherent anti-Stokes Raman signal of acetone sample which have Raman peak at the spectral finger-print region. In conclusion, the proposed method is more simple and cost-effective than the methods of previous research which use grating pairs and resonant photonic crystal slab. Furthermore, the proposed method can be used as endoscope application.

  12. Spectral interferometric Implementation with Passive Polarization Optics of Coherent Anti-Stokes Raman Spectroscopy

    OpenAIRE

    Littleton, Bradley; KAVANAGH, THOMAS; Festy, Frederic; Richards, David

    2013-01-01

    We have developed an interferometric implementation of coherent anti-Stokes Raman scattering which enables broadband coherent Raman spectroscopy free from the nonresonant background, with a signal strength proportional to concentration. Spectra encode mode symmetry information into the amplitude response, which can be directly compared to polarized spontaneous Raman spectra. The method requires only passive polarization optics and is suitable for a wide range of laser linewidths and pulse dur...

  13. 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.

    2012-01-01

    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 excitatio

  14. Coherent anti-Stokes Raman scattering microscopy for pharmaceutics: a shift in the right direction

    NARCIS (Netherlands)

    Fussell, Andrew Luke

    2014-01-01

    This dissertation demonstrates coherent anti-Stokes Raman scattering (CARS) microscopy as a tool in pharmaceutical solid state development. CARS microscopy is a nonlinear optical imaging technique that uses inelastic scattering of light to provide chemically specific imaging. CARS microscopy is suit

  15. Broadband multiplex coherent anti-Stokes Raman scattering microscopy employing photonic-crystal fibers

    DEFF Research Database (Denmark)

    Andresen, Esben Ravn; Paulsen, Henrik Nørgaard; Birkedal, Victoria;

    2006-01-01

    We demonstrate spectral multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopy and microscopy based on a single Ti:sapphire oscillator and a nonlinear photonic-crystal fiber (PCF). The Stokes pulse is generated by spectral conversion of the laser pulse in a PCF. The pump pulse is eit...

  16. Investigation of anti-Stokes Raman processes at phonon-polariton resonance: from Raman oscillation, frequency upconversion to Raman amplification.

    Science.gov (United States)

    Ding, Yujie J

    2015-03-01

    Raman oscillation, frequency upconversion, and Raman amplification can be achieved in a second-order nonlinear medium at the phonon-polariton resonance. By beating two optical fields, a second-order nonlinear polarization is generated inside the medium. Such a polarization induces a spatially uniform nonpropagating electric field at the beat frequency, which in turn mixes with the input optical field at the lower frequency to generate or amplify the anti-Stokes optical field. Raman oscillation can be efficiently reached for the copropagating configuration. In comparison, efficient frequency upconversion and large amplifications are achievable for the counterpropagating configuration. These Raman processes can be used to effectively remove transverse-optical phonons before decaying to lower-frequency phonons, achieve laser cooling, and significantly enhance coherent anti-Stokes Raman scattering. The counterpropagating configuration offers advantages for amplifying extremely weak signals. PMID:25723418

  17. Evaluation of turbulence induced noise in coherent anti-Stokes Raman scattering

    Science.gov (United States)

    Elliott, R. A.

    1982-01-01

    The effect of turbulence in a transonic wind tunnel on coherent anti-Stokes Raman scattering is considered. The driving pump and Stokes waves are taken to be coaxially propagating Gaussian beam waves which are focused on the Raman active medium through the turbulent boundary layer of the flow tube. The random index of refraction variations in the layer are modeled as phase perturbations of the driving waves which cause a reduction of the mean on-axis field and an increase in the mean diameter of the beams. Effective Gaussian beam parameters are developed and the radiated anti-Stokes power calculated as a function of the phase screen parameters. A significant reduction in signal strength occurs for realistic estimates of the phase screen parameter appropriate to a confined transonic flow. A method for estimating the signal degradation which could be applied to other experimental situations is presented.

  18. Raman scattering and anomalous Stokes–anti-Stokes ratio in MoTe2 atomic layers

    Science.gov (United States)

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

    2016-06-01

    Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings, which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain experimental conditions, and find the effect to be tunable by excitation frequency and number of atomic layers. These observations are interpreted as a result of resonance effects arising from the C excitons in the vicinity of the Brillouin zone center in the photon-electron-phonon interaction process.

  19. Raman scattering and anomalous Stokes-anti-Stokes ratio in MoTe2 atomic layers.

    Science.gov (United States)

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

    2016-01-01

    Stokes and anti-Stokes Raman scattering are performed on atomic layers of hexagonal molybdenum ditelluride (MoTe2), a prototypical transition metal dichalcogenide (TMDC) semiconductor. The data reveal all six types of zone center optical phonons, along with their corresponding Davydov splittings, which have been challenging to see in other TMDCs. We discover that the anti-Stokes Raman intensity of the low energy layer-breathing mode becomes more intense than the Stokes peak under certain experimental conditions, and find the effect to be tunable by excitation frequency and number of atomic layers. These observations are interpreted as a result of resonance effects arising from the C excitons in the vicinity of the Brillouin zone center in the photon-electron-phonon interaction process. PMID:27324297

  20. Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

    OpenAIRE

    Fussell, A.L.; Kleinebudde, P.; Herek, J. L.; Strachan, C J; Offerhaus, H. L.

    2014-01-01

    Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets...

  1. Design of supercontinuum source for coherent anti-Stokes Raman scattering microscopy

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hui; CHANG Sheng-jiang; ZHANG Yan-xin; ZHAO Xiang-ting

    2008-01-01

    A new method to obtain supemontinuum(SC)source for multiplex coherent anti-stokes Raman scattering(CARS)micros-copy is proposed.The nonlinear propagation in photonic-crystal fibers(PCF)of femtosecond pulse laser with central wavelength at 800.9 nm is studied with scalar wave theory.Based on the incident laser power and dispersion of PCF,super broadband source for multiplex CARS microscopy is designed.

  2. Revealing silent vibration modes of nanomaterials by detecting anti-Stokes hyper-Raman scattering with femtosecond laser pulses.

    Science.gov (United States)

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

    2016-01-21

    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. PMID:26690965

  3. Quantitative interpretation of time-resolved coherent anti-Stokes Raman spectroscopy with all Gaussian pulses

    CERN Document Server

    Ariunbold, Gombojav O

    2016-01-01

    Coherent Raman scattering spectroscopy is studied purposely, with the Gaussian ultrashort pulses as a hands-on elucidatory extraction tool of the clean coherent Raman resonant spectra from the overall measured data contaminated with the non-resonant four wave mixing background. The integral formulae for both the coherent anti-Stokes and Stokes Raman scattering are given in the semiclassical picture, and the closed-form solutions in terms of a complex error function are obtained. An analytic form of maximum enhancement of pure coherent Raman spectra at threshold time delay depending on bandwidth of probe pulse is also obtained. The observed experimental data for pyridine in liquid-phase are quantitatively elucidated and the inferred time-resolved coherent Raman resonant results are reconstructed with a new insight.

  4. Optimizing coherent anti-Stokes Raman scattering by genetic algorithm controlled pulse shaping

    Science.gov (United States)

    Yang, Wenlong; Sokolov, Alexei

    2010-10-01

    The hybrid coherent anti-Stokes Raman scattering (CARS) has been successful applied to fast chemical sensitive detections. As the development of femto-second pulse shaping techniques, it is of great interest to find the optimum pulse shapes for CARS. The optimum pulse shapes should minimize the non-resonant four wave mixing (NRFWM) background and maximize the CARS signal. A genetic algorithm (GA) is developed to make a heuristic searching for optimized pulse shapes, which give the best signal the background ratio. The GA is shown to be able to rediscover the hybrid CARS scheme and find optimized pulse shapes for customized applications by itself.

  5. Spectral model of time-domain coherent anti-Stokes Raman scattering

    CERN Document Server

    Marrocco, Michele

    2014-01-01

    We show that the increasingly popular nonlinear optical technique of time-domain coherent anti-Stokes Raman scattering (CARS), which is usually understood in terms of the semiclassical time-dependent third-order polarization, can be equally explained in terms of the time-delayed version of the Yuratich equation so popular in traditional frequency-domain CARS. The method brings out the strong dependence of CARS time traces and time-delayed CARS lineshapes on the spectral envelope of the probe laser electric field. Examples are analytically shown for experimental results that are otherwise treated by means of numerical methods only.

  6. Coherent anti-Stokes Raman scattering microscopy with dynamic speckle illumination

    Energy Technology Data Exchange (ETDEWEB)

    Heinrich, Christoph; Hofer, Alexander; Bernet, Stefan; Ritsch-Marte, Monika [Division for Biomedical Physics, Innsbruck Medical University, Muellerstrasse. 44, A-6020 Innsbruck (Austria)], E-mail: Stefan.Bernet@i-med.ac.at

    2008-02-15

    We demonstrate that dynamic speckle patterns can be utilized to improve the optical sectioning power of wide-field coherent anti-Stokes Raman scattering (CARS) microscopy. The time-dependent speckle patterns are generated by randomly moving a multimode fiber delivering one of the excitation laser pulses. The standard deviation of various CARS images with changing speckle illumination yields an enhanced axial resolution as compared with a simply averaged CARS image. The procedure makes use of the intrinsically high speckle contrast even in scattering materials.

  7. Experimental Investigation on Selective Excitation of Two-Pulse Coherent Anti-Stokes Raman Scattering

    Institute of Scientific and Technical Information of China (English)

    LI Xia; ZHANG Hui; ZHANG Xiang-Yun; ZHANG Shi-An; WANG Zu-Geng; SUN Zhen-Rong

    2008-01-01

    Selective excitation of coherent anti-Stokes Raman scattering from the benzene solution is achieved by adaptive pulse shaping based on genetic algorithm, and second harmonic generation frequency-resolved optical gating (SHG-FROG) technique is adopted to characterize the original and optimal laser pulses. The mechanism for two-pulse coherent mode-selective excitation of Raman scattering is experimentally investigated by modulating the pump pulse in the frequency domain, and it is indicated that two-pulse coherent mode-selective excitation of Raman scattering mainly depends on the effective frequency components of the pump pulse related to specific vibrational mode. The experimental results suggest that two-pulse CARS has good signal-to-background ratio and high sensitivity, and it has attractive potential applications in the complicated molecular system.

  8. Direct imaging of molecular symmetry by coherent anti-Stokes Raman scattering

    CERN Document Server

    Cleff, Carsten; Ferrand, Patrick; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

    2015-01-01

    Nonlinear optical methods, such as coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), are able to perform label free imaging, with chemical bonds specificity. Here, we demonstrate that the use of circularly polarized light allows to retrieve not only the chemical nature but also the symmetry of the probed sample, in a single shot measurement. Our symmetry-resolved scheme offers simple access to the local organization of vibrational bonds and as a result provides enhanced image contrast for anisotropic samples as well as an improved chemical selectivity. We quantify the local organization of vibrational bonds on crystalline and biological samples, thus providing new information not accessible by spontaneous Raman and SRS techniques. This work stands for a novel symmetry-resolved contrast in vibrational microscopy, with potential application in biological diagnostic.

  9. Broadband coherent anti-Stokes Raman scattering light generation in BBO crystal by using two crossing femtosecond laser pulses.

    Science.gov (United States)

    Liu, Jun; Zhang, Jun; Kobayashi, Takayoshi

    2008-07-01

    As broad as 12000 cm(-1) coherent anti-Stokes Raman scattering (CARS) light from ultraviolet to infrared was generated in a BBO crystal by using two crossing femtosecond laser pulses with 30% conversion efficiency. More than fifteenth-order anti-Stokes and second-order Stokes Raman sidebands were observed with nice Gaussian spatial mode. The effect of the crossing angle between two input beams on the spectrum and emitting angle of the Raman sidebands was studied in detail. Calculation shows that the phase-matching condition determines the frequencies and angles of the sidebands.

  10. Broadband coherent anti-Stokes Raman scattering light generation in BBO crystal by using two crossing femtosecond laser pulses.

    Science.gov (United States)

    Liu, Jun; Zhang, Jun; Kobayashi, Takayoshi

    2008-07-01

    As broad as 12000 cm(-1) coherent anti-Stokes Raman scattering (CARS) light from ultraviolet to infrared was generated in a BBO crystal by using two crossing femtosecond laser pulses with 30% conversion efficiency. More than fifteenth-order anti-Stokes and second-order Stokes Raman sidebands were observed with nice Gaussian spatial mode. The effect of the crossing angle between two input beams on the spectrum and emitting angle of the Raman sidebands was studied in detail. Calculation shows that the phase-matching condition determines the frequencies and angles of the sidebands. PMID:18594676

  11. Revealing silent vibration modes of nanomaterials by detecting anti-Stokes hyper-Raman scattering with femtosecond laser pulses

    Science.gov (United States)

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

    2016-01-01

    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.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

  12. Spontaneous Raman and Coherent Anti-Stokes Raman Spectroscopy of Infrared Multiphoton-Excited Molecules.

    Science.gov (United States)

    Chen, Kuei-Hsien

    This thesis is a study of infrared multiphoton excitation using spontaneous and coherent anti-Stokes Raman spectroscopy. The spontaneous Raman measurements provide information on the intramolecular vibrational energy distribution over the different modes. This information is complemented by the CARS measurements which make it possible to perform state-specific studies of the vibrational and rotational distribution. For SF_6, the time-resolved spontaneous Raman measurements show complete equilibrium of energy from the pump mode to other vibrational modes. In contrast, for smaller molecules such as CF_2 Cl_2, a nonthermal energy distribution is observed after excitation. These measurements therefore disprove the general belief that the intramolecular energy distribution in infrared multiphoton molecules is always in equilibrium. The CARS measurements on bulk OCS provide values for the anharmonicities and for the energy transfer rates between modes. In addition the spectra show a very fast relaxation of the vibrational energy within the nu_2 mode. For SO_2 , the CARS measurements show that it is the nu_1 symmetric stretching mode and not the overtone excitation of the nu_2 bending mode that is pumped by the CO_2 laser. Moreover, it is shown that the hot bands of SO_2 have been incorrectly assigned up to now. Corrected values for the anharmonicities are given. In the second half of the thesis, a pulsed supersonic molecular beam is added to the infrared multiphoton excitation study. Combined with the state-specific CARS technique, the collisionless and internally cooled molecules in the beam open the door to a more detailed study of the excitation process. Pure rotational CARS is used to study the change in rotational distribution of ethylene due to infrared excitation in the beam. The appearance of rotational holes reveal which rotational states are pumped by the CO _2 laser. For OCS the evolution of the overtone population into a thermal distribution is studied

  13. Coherent anti-Stokes Raman scattering for label-free biomedical imaging

    International Nuclear Information System (INIS)

    Coherent anti-Stokes Raman scattering (CARS) has established itself as an imaging technique capable of providing video-rate imaging of biological specimens through vibrational coherence of endogenous molecules. Current techniques predominantly involve the application of costly, invasive and potentially non-specific dyes or labels for imaging biomolecules. CARS microscopy can however provide a high-resolution and non-invasive alternative for imaging biomolecules of interest without the need for exogenous labels. Here we provide an overview of CARS including the technique and common instrumentation as well as its applications in biomedical imaging. We discuss the major biomedical areas where CARS has been applied such as in evaluating liver disease, progression of atherosclerosis, tumour classification and tracking drug delivery, whilst also assessing the future challenges for clinical translation. (special issue article)

  14. Langevin analysis of fundamental noise limits in coherent anti-Stokes Raman spectroscopy

    International Nuclear Information System (INIS)

    We use a Langevin approach to analyze the quantum noise in coherent anti-Stokes Raman spectroscopy in several experimental scenarios: with continuous-wave input fields acting simultaneously and with fast sequential pulsed lasers where one field scatters off the coherence generated by other fields and for interactions within a cavity and in free space. In all cases, the signal and quantum noise due to spontaneous decay and decoherence in the medium are shown to be described by the same general expression. Our theory in particular shows that for short interaction times, the medium noise is not important and the efficiency is limited only by the intrinsic quantum nature of the photon. We obtain fully analytic results without making an adiabatic approximation; the fluctuations of the medium and the fields are solved self-consistently

  15. Visualizing resonances in the complex plane with vibrational phase contrast coherent anti-Stokes Raman scattering.

    Science.gov (United States)

    Jurna, Martin; Garbacik, Erik T; Korterik, Jeroen P; Herek, Jennifer L; Otto, Cees; Offerhaus, Herman L

    2010-09-15

    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 response can be determined, and the nonresonant background rejected, by extracting the imaginary component of the complex response, enhancing the sensitivity of CARS measurements. Second, selectivity is increased via determination of the phase and amplitude, allowing separation of individual molecular components of a sample even when their vibrational bands overlap. Here, using vibrational phase contrast CARS (VPC-CARS), we demonstrate enhanced sensitivity in quantitative measurements of ethanol/methanol mixtures and increased selectivity in a heterogeneous mixture of plastics and water. This powerful technique opens a wide range of possibilities for studies of complicated systems where overlapping resonances limit standard methodologies. PMID:20731373

  16. Characterization of Microstructures Fabricated by Two-Photon Polymerization Using Coherent Anti-Stokes Raman Scattering Microscopy

    OpenAIRE

    Baldacchini, Tommaso; Zimmerley, Maxwell; Kuo, Chun-Hung; Potma, Eric O.; Zadoyan, Ruben

    2009-01-01

    We demonstrate the possibility to image microstructures fabricated by two-photon polymerization (TPP) using coherent anti-Stokes Raman scattering (CARS) microscopy. The imaging contrast based on chemical selectivity attained by CARS microscopy is used to gather qualitative information on TPP. Upon the basis of detailed knowledge of the characteristic signatures of the photoresist Raman spectrum, quantitative relationships between laser writing conditions and polymer cross-linking are demonstr...

  17. Raman spectroscopy and coherent anti-Stokes Raman scattering imaging: prospective tools for monitoring skeletal cells and skeletal regeneration

    Science.gov (United States)

    Moura, Catarina Costa; Tare, Rahul S.; Oreffo, Richard O. C.; Mahajan, Sumeet

    2016-01-01

    The use of skeletal stem cells (SSCs) for cell-based therapies is currently one of the most promising areas for skeletal disease treatment and skeletal tissue repair. The ability for controlled modification of SSCs could provide significant therapeutic potential in regenerative medicine, with the prospect to permanently repopulate a host with stem cells and their progeny. Currently, SSC differentiation into the stromal lineages of bone, fat and cartilage is assessed using different approaches that typically require cell fixation or lysis, which are invasive or even destructive. Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy present an exciting alternative for studying biological systems in their natural state, without any perturbation. Here we review the applications of Raman spectroscopy and CARS imaging in stem-cell research, and discuss the potential of these two techniques for evaluating SSCs, skeletal tissues and skeletal regeneration as an exemplar. PMID:27170652

  18. Combined spontaneous Stokes and coherent anti-Stokes Raman scattering spectroscopy

    Science.gov (United States)

    Becker, Karina; Kiefer, Johannes

    2016-05-01

    The simultaneous determination of multiple parameters is the key in the characterization of processes and materials that change with time. In combustion environments, the combined measurement of temperature and chemical composition is particularly desirable. In the present work, possible approaches for the simultaneous application of spontaneous Raman scattering (RS) and coherent anti-Stokes Raman scattering (CARS) spectroscopy are proposed and analyzed. While RS provides concentration information of all major species, vibrational CARS is a highly accurate thermometry tool at flame conditions. Five experimentally feasible CARS-RS schemes are identified and discussed with respect to signal intensity, measurement volume, and experimental complexity. From this analysis, one scheme was found to be the best option. It utilizes a broadband dye laser centered at 852 nm as a pump and the fundamental 1064-nm radiation of the Nd:YAG as Stokes laser. The third harmonic is used as CARS probe and RS laser. The experimentally most elegant scheme replaces the third harmonic in the above scheme by the second harmonic hence involving the smallest number of optical components in the setup.

  19. Coherent anti-stokes Raman spectroscopy for detecting explosives in real time

    Science.gov (United States)

    Dogariu, Arthur; Pidwerbetsky, Alex

    2012-06-01

    We demonstrate real-time stand-off detection and imaging of trace explosives using collinear, backscattered Coherent Anti-Stokes Raman Spectroscopy (CARS). Using a hybrid time-resolved broad-band CARS we identify nanograms of explosives on the millisecond time scale. The broad-band excitation in the near-mid-infrared region excites the vibrational modes in the fingerprint region, and the time-delayed probe beam ensures the reduction of any non-resonant contributions to the CARS signal. The strong coherent enhancement allows for recording Raman spectra in real-time. We demonstrate stand-off detection by acquiring, analyzing, and identifying vibrational fingerprints in real-time with very high sensitivity and selectivity. By extending the focused region from a 100-micron sized spot to a 5mm long line we can obtain the spectral information from an extended region of the remote target with high spatial resolution. We demonstrate fast hyperspectral imaging by one-dimensional scanning of the Line-CARS. The three-dimensional data structure contains the vibrational spectra of the target at each sampled location, which allows for chemical mapping of the remote target.

  20. Femtosecond Coherent Anti-Stokes Raman Scattering Gas Phase Thermometry at 5 kHz

    Science.gov (United States)

    Fineman, Claresta; Lucht, Robert

    2014-05-01

    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.

  1. Investigation of porous media combustion by coherent anti-Stokes Raman spectroscopy

    Science.gov (United States)

    Weikl, M. C.; Tedder, S. A.; Seeger, T.; Leipertz, A.

    2010-10-01

    High efficiency, marginal pollutant emissions and low fuel consumption are desirable standards for modern combustion devices. The porous burner technology is a modern type of energy conversion with a strong potential to achieve these standards. However, due to the solid ceramic framework investigation of the thermodynamic properties of combustion, for example temperature, is difficult. The combustion process inside the ceramic structure of a porous burner was experimentally investigated by coherent anti-Stokes Raman spectroscopy (CARS). In this work, we present measurements using dual-pump dual-broadband CARS (DP-DBB-CARS) of temperature and species concentrations inside the reaction and flue gas zone of a porous media burner. Improvements to the setup and data evaluation procedure in contrast to previous measurements are discussed in detail. The results at varied thermal power and stoichiometry are presented. In addition, measurements at a range of radial positions inside a pore are conducted and correlated with the solid structure of the porous foam, which was determined by X-ray computer tomography.

  2. Coherent anti-Stokes Raman scattering microscopy of human smooth muscle cells in bioengineered tissue scaffolds

    Science.gov (United States)

    Brackmann, Christian; Esguerra, Maricris; Olausson, Daniel; Delbro, Dick; Krettek, Alexandra; Gatenholm, Paul; Enejder, Annika

    2011-02-01

    The integration of living, human smooth muscle cells in biosynthesized cellulose scaffolds was monitored by nonlinear microscopy toward contractile artificial blood vessels. Combined coherent anti-Stokes Raman scattering (CARS) and second harmonic generation (SHG) microscopy was applied for studies of the cell interaction with the biopolymer network. CARS microscopy probing CH2-groups at 2845 cm-1 permitted three-dimensional imaging of the cells with high contrast for lipid-rich intracellular structures. SHG microscopy visualized the fibers of the cellulose scaffold, together with a small signal obtained from the cytoplasmic myosin of the muscle cells. From the overlay images we conclude a close interaction between cells and cellulose fibers. We followed the cell migration into the three-dimensional structure, illustrating that while the cells submerge into the scaffold they extrude filopodia on top of the surface. A comparison between compact and porous scaffolds reveals a migration depth of <10 μm for the former, whereas the porous type shows cells further submerged into the cellulose. Thus, the scaffold architecture determines the degree of cell integration. We conclude that the unique ability of nonlinear microscopy to visualize the three-dimensional composition of living, soft matter makes it an ideal instrument within tissue engineering.

  3. Coherent anti-Stokes Raman scattering (CARS) microscopy visualizes pharmaceutical tablets during dissolution.

    Science.gov (United States)

    Fussell, Andrew L; Kleinebudde, Peter; Herek, Jennifer; Strachan, Clare J; Offerhaus, Herman L

    2014-01-01

    Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and structure can change during dissolution, it is essential to monitor it during dissolution testing. In this work coherent anti-Stokes Raman scattering microscopy is used to image the surface of tablets during dissolution while UV absorption spectroscopy is simultaneously providing inline analysis of dissolved drug concentration for tablets containing a 50% mixture of theophylline anhydrate and ethyl cellulose. The measurements showed that in situ CARS microscopy is capable of imaging selectively theophylline in the presence of ethyl cellulose. Additionally, the theophylline anhydrate converted to theophylline monohydrate during dissolution, with needle-shaped crystals growing on the tablet surface during dissolution. The conversion of theophylline anhydrate to monohydrate, combined with reduced exposure of the drug to the flowing dissolution medium resulted in decreased dissolution rates. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring pharmaceutical tablet dissolution and correlating surface changes with changes in dissolution rate. PMID:25045833

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

    Science.gov (United States)

    Fussell, Andrew; Garbacik, Erik; Offerhaus, Herman; Kleinebudde, Peter; Strachan, Clare

    2013-11-01

    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 anti-Stokes Raman scattering (CARS) microscopy provides rapid, spectrally selective imaging to monitor the oral dosage form during dissolution. In this study, in situ CARS microscopy was combined with inline UV absorption spectroscopy to monitor the solid-state change in oral dosage forms containing theophylline anhydrate undergoing dissolution and to correlate the solid-state change with a change in dissolution rate. The results from in situ CARS microscopy showed that theophylline anhydrate converted to theophylline monohydrate during dissolution resulting in a reduction in the dissolution rate. The addition of methyl cellulose to the dissolution medium was found to delay the theophylline monohydrate growth and changed the morphology of the monohydrate. The net effect was an increased dissolution rate for theophylline anhydrate. Our results show that in situ CARS microscopy combined with inline UV absorption spectroscopy is capable of monitoring oral dosage forms undergoing dissolution and correlating changes in solid-state form with changes in dissolution rate. PMID:23994672

  5. Coherent anti-Stokes Raman scattering hyperspectral imaging of cartilage aiming for state discrimination of cell

    Science.gov (United States)

    Shiozawa, Manabu; Shirai, Masataka; Izumisawa, Junko; Tanabe, Maiko; Watanabe, Koich

    2016-07-01

    Noninvasive cell analyses are increasingly important in the medical field. A coherent anti-Stokes Raman scattering (CARS) microscope is the noninvasive imaging equipment and enables to obtain images indicating molecular distribution. However, due to low-signal intensity, it is still challenging to obtain images of the fingerprint region, in which many spectrum peaks correspond to compositions of a cell. Here, to identify cell differentiation by using multiplex CARS, we investigated hyperspectral imaging of the fingerprint region of living cells. To perform multiplex CARS, we used a prototype of a compact light source generating both pump light and broadband Stokes light. Assuming application to regenerative medicine, we chose a cartilage cell, whose differentiation is difficult to be identified by change of the cell morphology. Because one of the major components of cartilage is collagen, we focused on distribution of proline, which accounts for approximately 20% of collagen. The spectrum quality was improved by optical adjustments of the power branching ratio and divergence of Stokes light. Periphery of a cartilage cell was highlighted in a CARS image of proline, and this result suggests correspondence with collagen generated as an extracellular matrix. The possibility of noninvasive analyses by using CARS hyperspectral imaging was indicated.

  6. Investigation of lipid homeostasis in living Drosophila by coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

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

    2012-12-01

    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.

  7. Rotational coherence imaging and control for CN molecules through time-frequency resolved coherent anti-Stokes Raman scattering

    OpenAIRE

    Lindgren, Johan; Hulkko, Eero; Pettersson, Mika; Kiljunen, Toni

    2011-01-01

    Numerical wave packet simulations are performed for studying coherent anti-Stokes Raman scattering (CARS) for CN radicals. Electronic coherence is created by femtosecond laser pulses between the X²Σ and B²Σ states. Due to the large energy separation of vibrational states, the wave packets are superpositions of rotational states only. This allows for a specially detailed inspection of the second- and third-order coherences by a two-dimensional imaging approach. We present the time-frequency do...

  8. Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering for gas-phase temperature measurements

    Science.gov (United States)

    Miller, Joseph Daniel

    Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) is employed for quantitative gas-phase temperature measurements in combustion processes and heated flows. In this approach, ultrafast 100-fs laser pulses are used to induce vibrational and rotational transitions in N2 and O2, while a third spectrally narrowed picosecond pulse is used to probe the molecular response. Temporal suppression of the nonresonant contribution and elimination of collisional effects are achieved by delay of the probe pulse, while sufficient spectral resolution is maintained for frequency-domain detection and thermometry. A theoretical framework is developed to model experimental spectra by phenomenologically describing the temporal evolution of the vibrational and rotational wavepackets as a function of temperature and pressure. Interference-free, single-shot vibrational fs/ps CARS thermometry is demonstrated at 1-kHz from 1400-2400 K in a H2-air flame, with accuracy better than 3%. A time-asymmetric exponential pulse shape is introduced to optimize nonresonant suppression with a 103 reduction at a probe delay of 0.31 ps. Low-temperature single-shot thermometry (300-700 K) with better than 1.5% accuracy is demonstrated using a fully degenerate rotational fs/ps CARS scheme, and the influence of collision energy transfer on thermometry error is quantified at atmospheric pressure. Interference-free thermometry, without nonresonant contributions and collision-induced error, is demonstrated for the first time using rotational fs/ps CARS at room temperature and pressures from 1-15 atm. Finally, the temporal and spectral resolution of fs/ps CARS is exploited for transition-resolved time-domain measurements of N2 and O2 self-broadened S-branch Raman linewidths at pressures of 1-20 atm.

  9. Temperature measurements in metalized propellant combustion using hybrid fs/ps coherent anti-Stokes Raman scattering.

    Science.gov (United States)

    Kearney, Sean P; Guildenbecher, Daniel R

    2016-06-20

    We apply ultrafast pure-rotational coherent anti-Stokes Raman scattering (CARS) for temperature and relative oxygen concentration measurements in the plume emanating from a burning, aluminized ammonium-perchlorate propellant strand. Combustion of these metal-based propellants is a particularly hostile environment for laser-based diagnostics, with intense background luminosity and scattering from hot metal particles as large as several hundred micrometers in diameter. CARS spectra that were previously obtained using nanosecond pulsed lasers in an aluminum-particle-seeded flame are examined and are determined to be severely impacted by nonresonant background, presumably as a result of the plasma formed by particulate-enhanced laser-induced breakdown. Introduction of femtosecond/picosecond (fs/ps) laser pulses improves CARS detection by providing time-gated elimination of strong nonresonant background interference. Single-laser-shot fs/ps CARS spectra were acquired from the burning propellant plume, with picosecond probe-pulse delays of 0 and 16 ps from the femtosecond pump and Stokes pulses. At zero delay, nonresonant background overwhelms the Raman-resonant spectroscopic features. Time-delayed probing results in the acquisition of background-free spectra that were successfully fit for temperature and relative oxygen content. Temperature probability densities and temperature/oxygen correlations were constructed from ensembles of several thousand single-laser-shot measurements with the CARS measurement volume positioned within 3 mm or less of the burning propellant surface. The results show that ultrafast CARS is a potentially enabling technology for probing harsh, particle-laden flame environments. PMID:27409125

  10. Diagnosing lung cancer using coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

    Gao, Liang; Yang, Yaliang; Xing, Jiong; Thrall, Michael J.; Wang, Zhiyong; Li, Fuhai; Luo, Pengfei; Wong, Kelvin K.; Zhao, Hong; Wong, Stephen T. C.

    2011-03-01

    Lung carcinoma is the most prevalent type of cancer in the world, and it is responsible for more deaths than other types of cancer. During diagnosis, a pathologist primarily aims to differentiate small cell carcinoma from non-small cell carcinoma on biopsy and cytology specimens, which is time consuming due to the time required for tissue processing and staining. To speed up the diagnostic process, we investigated the feasibility of using coherent anti-Stokes Raman scattering (CARS) microscopy as a label-free strategy to image lung lesions and differentiate subtypes of lung cancers. Different mouse lung cancer models were developed by injecting human lung cancer cell lines, including adenocarcinoma, squamous cell carcinoma, and small cell carcinoma, into lungs of the nude mice. CARS images were acquired from normal lung tissues and different subtypes of cancer lesions ex vivo using intrinsic contrasts from symmetric CH2 bonds. These images showed good correlation with the hematoxylin and eosin (H&E) stained sections from the same tissue samples with regard to cell size, density, and cell-cell distance. These features are routinely used in diagnosing lung lesions. Our results showed that the CARS technique is capable of providing a visualizable platform to differentiate different kinds of lung cancers using the same pathological features without histological staining and thus has the potential to serve as a more efficient examination tool for diagnostic pathology. In addition, incorporating with suitable fiber-optic probes would render the CARS technique as a promising approach for in vivo diagnosis of lung cancer.

  11. Compact fibre-based coherent anti-Stokes Raman scattering spectroscopy and interferometric coherent anti-Stokes Raman scattering from a single femtosecond fibre-laser oscillator

    Indian Academy of Sciences (India)

    Vikas Kumar; Alessio Gambetta; Cristian Manzoni; Roberta Ramponi; Giulio Cerullo; Marco Marangoni

    2010-12-01

    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 nonlinear crystals) of femtosecond pulses emitted by a single compact Er-fibre oscillator. For a far better signal to non-resonant background contrast, interferometric CARS (I-CARS) is demonstrated and CARS signal enhancement upto three orders of magnitude is achieved by constructive interference with an auxiliary local oscillator at anti-Stokes field, also synthesized by spectral compression of pulses emitted from the same fibre oscillator.

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

    Energy Technology Data Exchange (ETDEWEB)

    Rigby, Stephanie J. [Centre for Research in Energy and Environment, School of Engineering, Robert Gordon University, Aberdeen AB10 1FR (United Kingdom); Al-Obaidi, Ala H.R. [Smart Light Devices, Unit 13, Tyseal Base, Craigshaw Crescent Aberdeen, West Tullos Industrial Estate, Aberdeen AB12 3AW (United Kingdom); Lee, Soo-Keun [School of Environmental Science and Engineering, POSTECH, San 31 Hyoja Dong Nam-Gu, Pohang, Kyungpook 790-784 (Korea, Republic of); McStay, Daniel [Discovery Technologies Ltd., Redshank House, Alness Point Business Park, Alness IV17 0IJ (United Kingdom); Robertson, Peter K.J. [Centre for Research in Energy and Environment, School of Engineering, The Robert Gordon University, Aberdeen AB10 1FR (United Kingdom)]. E-mail: peter.robertson@rgu.ac.uk

    2006-09-15

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

  13. Rotational coherence imaging and control for CN molecules through time-frequency resolved coherent anti-Stokes Raman scattering.

    Science.gov (United States)

    Lindgren, Johan; Hulkko, Eero; Pettersson, Mika; Kiljunen, Toni

    2011-12-14

    Numerical wave packet simulations are performed for studying coherent anti-Stokes Raman scattering (CARS) for CN radicals. Electronic coherence is created by femtosecond laser pulses between the X(2)Σ and B(2)Σ states. Due to the large energy separation of vibrational states, the wave packets are superpositions of rotational states only. This allows for a specially detailed inspection of the second- and third-order coherences by a two-dimensional imaging approach. We present the time-frequency domain images to illustrate the intra- and intermolecular interferences, and discuss the procedure to rationally control and experimentally detect the interferograms in solid Xe environment. PMID:22168710

  14. Detection of chemical interfaces in coherent anti-Stokes Raman scattering microscopy: Dk-CARS. I. Axial interfaces.

    Science.gov (United States)

    Gachet, David; Rigneault, Hervé

    2011-12-01

    We develop a full vectorial theoretical investigation of the chemical interface detection in conventional coherent anti-Stokes Raman scattering (CARS) microscopy. In Part I, we focus on the detection of axial interfaces (i.e., parallel to the optical axis) following a recent experimental demonstration of the concept [Phys. Rev. Lett. 104, 213905 (2010)]. By revisiting the Young's double slit experiment, we show that background-free microscopy and spectroscopy is achievable through the angular analysis of the CARS far-field radiation pattern. This differential CARS in k space (Dk-CARS) technique is interesting for fast detection of interfaces between molecularly different media. It may be adapted to other coherent and resonant scattering processes.

  15. Longitudinal in vivo coherent anti-Stokes Raman scattering imaging of demyelination and remyelination in injured spinal cord

    Science.gov (United States)

    Shi, Yunzhou; Zhang, Delong; Huff, Terry B.; Wang, Xiaofei; Shi, Riyi; Xu, Xiao-Ming; Cheng, Ji-Xin

    2011-10-01

    In vivo imaging of white matter is important for the mechanistic understanding of demyelination and evaluation of remyelination therapies. Although white matter can be visualized by a strong coherent anti-Stokes Raman scattering (CARS) signal from axonal myelin, in vivo repetitive CARS imaging of the spinal cord remains a challenge due to complexities induced by the laminectomy surgery. We present a careful experimental design that enabled longitudinal CARS imaging of de- and remyelination at single axon level in live rats. In vivo CARS imaging of secretory phospholipase A2 induced myelin vesiculation, macrophage uptake of myelin debris, and spontaneous remyelination by Schwann cells are sequentially monitored over a 3 week period. Longitudinal visualization of de- and remyelination at a single axon level provides a novel platform for rational design of therapies aimed at promoting myelin plasticity and repair.

  16. In vivo histology: optical biopsies with chemical contrast using clinical multiphoton/coherent anti-Stokes Raman scattering tomography

    Science.gov (United States)

    Weinigel, M.; Breunig, H. G.; Kellner-Höfer, M.; Bückle, R.; Darvin, M. E.; Klemp, M.; Lademann, J.; König, K.

    2014-05-01

    The majority of existing coherent anti-Stokes Raman scattering (CARS) imaging systems are still huge and complicated laboratory systems and neither compact nor user-friendly nor mobile medically certified CARS systems. We have developed a new flexible multiphoton/CARS tomograph for imaging in a clinical environment. The system offers exceptional 360° flexibility with a very stable setup and enables label free ‘in vivo histology’ with chemical contrast within seconds. It can be completely operated by briefly trained non-laser experts. The imaging capability and flexibility of the novel in vivo tomograph are shown on optical biopsies with subcellular resolution and chemical contrast of patients suffering from psoriasis and squamous cell carcinoma.

  17. Background-free coherent anti-stokes Raman spectroscopy and microscopy by dual-soliton pulse generation

    CERN Document Server

    Chen, Kun; Wei, Haoyun; Li, Yan

    2016-01-01

    We propose an all-fiber-generated dual-soliton pulses based scheme for the background-free detection of coherent anti-Stokes Raman spectroscopy under the spectral focusing mechanism. Due to the strong birefringence and high nonlinearity of a polarization-maintaining photonic crystal fiber (PM-PCF), two redshifted soliton pulses can be simultaneously generated relying on high-order dispersion and nonlinear effects along two eigenpolarization axes in the anomalous dispersion regime, while allowing feasible tunability of the frequency distance and temporal interval between them. This proposed scheme, termed as DS-CARS, exploits a unique combination of slight frequency-shift and advisable temporal walk-off of this two soliton pulses to achieve robust and efficient suppression of nonresonant background with compact all-fiber coherent excitation source. Capability of the DS-CARS is experimentally demonstrated by the background-free CARS spectroscopy and unambiguous CARS microscopy of polymer beads in the fingerprin...

  18. In vivo histology: optical biopsies with chemical contrast using clinical multiphoton/coherent anti-Stokes Raman scattering tomography

    International Nuclear Information System (INIS)

    The majority of existing coherent anti-Stokes Raman scattering (CARS) imaging systems are still huge and complicated laboratory systems and neither compact nor user-friendly nor mobile medically certified CARS systems. We have developed a new flexible multiphoton/CARS tomograph for imaging in a clinical environment. The system offers exceptional 360° flexibility with a very stable setup and enables label free ‘in vivo histology’ with chemical contrast within seconds. It can be completely operated by briefly trained non-laser experts. The imaging capability and flexibility of the novel in vivo tomograph are shown on optical biopsies with subcellular resolution and chemical contrast of patients suffering from psoriasis and squamous cell carcinoma

  19. Dual-soliton Stokes-based background-free coherent anti-Stokes Raman scattering spectroscopy and microscopy.

    Science.gov (United States)

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

    2016-06-01

    We propose an all-fiber-generated, dual-soliton, Stokes-based scheme for background-free coherent anti-Stokes Raman scattering (CARS) under the spectral focusing mechanism. Owing to the strong birefringence and high nonlinearity of a polarization-maintaining PCF (PM-PCF), two soliton pulses can be simultaneously emitted along different eigenpolarization axes and both serve as Stokes pulses, while allowing feasible tunability of frequency distance and temporal interval between them. This proposed scheme, based on an all-fiber light source, exploits a unique combination of slight frequency-shift temporal walk-off of these two solitons to achieve efficient suppression of the nonresonant background and beat the inaccessibility and complexity of the excitation source. Capability is experimentally demonstrated by background-free CARS spectroscopy and unambiguous CARS microscopy in the fingerprint region. PMID:27244431

  20. Seeing the vibrational breathing of a single molecule through time-resolved coherent anti-Stokes Raman scattering

    CERN Document Server

    Yampolsky, Steven; Dey, Shirshendu; Hulkko, Eero; Banik, Mayukh; Potma, Eric O; Apkarian, Vartkess A

    2014-01-01

    The motion of chemical bonds within molecules can be observed in real time, in the form of vibrational wavepackets prepared and interrogated through ultrafast nonlinear spectroscopy. Such nonlinear optical measurements are commonly performed on large ensembles of molecules, and as such, are limited to the extent that ensemble coherence can be maintained. Here, we describe vibrational wavepacket motion on single molecules, recorded through time-resolved, surface-enhanced, coherent anti-Stokes Raman scattering. The required sensitivity to detect the motion of a single molecule, under ambient conditions, is achieved by equipping the molecule with a dipolar nano-antenna (a gold dumbbell). In contrast with measurements in ensembles, the vibrational coherence on a single molecule does not dephase. It develops phase fluctuations with characteristic statistics. We present the time evolution of discretely sampled statistical states, and highlight the unique information content in the characteristic, early-time probabi...

  1. Selective excitation of molecular mode in a mixture by femtosecond resonance-enhanced coherent anti-Stokes Raman scattering spectroscopy

    Institute of Scientific and Technical Information of China (English)

    He Ping; Li Si-Ning; Fan Rong-Wei; Li Xiao-Hui; Xia Yuan-Qin; Yu Xin; Chen De-Ying

    2012-01-01

    Femtosecond time-resolved coherent anti-Stokes Raman scattering (CARS) spectroscopy is used to investigate gaseous molecular dynamics.Due to the spectrally broad laser pulses,usually poorly resolved spectra result from this broad spectroscopy.However,it can be demonstrated that by the electronic resonance enhancement optimization control a selective excitation of specific vibrational mode is possible.Using an electronically resonance-enhanced effect,iodine molecule specific CARS spectroscopy can be obtained from a mixture of iodine-air at room temperature and a pressure of 1 atm (corresponding to a saturation iodine vapour as low as about 35 Pa).The dynamics on either the electronically excited state or the ground state of iodine molecules obtained is consistent with previous studies (vacuum,heated and pure iodine) in the femtosecond time resolved CARS spectroscopy,showing that an effective method of suppressing the non-resonant CARS background and other interferences is demonstrated.

  2. Polyglutamine aggregate structure in vitro and in vivo; new avenues for coherent anti-Stokes Raman scattering microscopy.

    Science.gov (United States)

    Perney, Nicolas M; Braddick, Lucy; Jurna, Martin; Garbacik, Erik T; Offerhaus, Herman L; Serpell, Louise C; Blanch, Ewan; Holden-Dye, Lindy; Brocklesby, William S; Melvin, Tracy

    2012-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is applied for the first time for the evaluation of the protein secondary structure of polyglutamine (polyQ) aggregates in vivo. Our approach demonstrates the potential for translating information about protein structure that has been obtained in vitro by X-ray diffraction into a microscopy technique that allows the same protein structure to be detected in vivo. For these studies, fibres of polyQ containing peptides (D(2)Q(15)K(2)) were assembled in vitro and examined by electron microscopy and X-ray diffraction methods; the fibril structure was shown to be cross β-sheet. The same polyQ fibres were evaluated by Raman spectroscopy and this further confirmed the β-sheet structure, but indicated that the structure is highly rigid, as indicated by the strong Amide I signal at 1659 cm(-1). CARS spectra were simulated using the Raman spectrum taking into account potential non-resonant contributions, providing evidence that the Amide I signal remains strong, but slightly shifted to lower wavenumbers. Combined CARS (1657 cm(-1)) and multi-photon fluorescence microscopy of chimeric fusions of yellow fluorescent protein (YFP) with polyQ (Q40) expressed in the body wall muscle cells of Caenorhabditis elegans nematodes (1 day old adult hermaphrodites) revealed diffuse and foci patterns of Q40-YFP that were both fluorescent and exhibited stronger CARS (1657 cm(-1)) signals than in surrounding tissues at the resonance for the cross β-sheet polyQ in vitro. PMID:22911702

  3. Polyglutamine aggregate structure in vitro and in vivo; new avenues for coherent anti-Stokes Raman scattering microscopy.

    Directory of Open Access Journals (Sweden)

    Nicolas M Perney

    Full Text Available Coherent anti-Stokes Raman scattering (CARS microscopy is applied for the first time for the evaluation of the protein secondary structure of polyglutamine (polyQ aggregates in vivo. Our approach demonstrates the potential for translating information about protein structure that has been obtained in vitro by X-ray diffraction into a microscopy technique that allows the same protein structure to be detected in vivo. For these studies, fibres of polyQ containing peptides (D(2Q(15K(2 were assembled in vitro and examined by electron microscopy and X-ray diffraction methods; the fibril structure was shown to be cross β-sheet. The same polyQ fibres were evaluated by Raman spectroscopy and this further confirmed the β-sheet structure, but indicated that the structure is highly rigid, as indicated by the strong Amide I signal at 1659 cm(-1. CARS spectra were simulated using the Raman spectrum taking into account potential non-resonant contributions, providing evidence that the Amide I signal remains strong, but slightly shifted to lower wavenumbers. Combined CARS (1657 cm(-1 and multi-photon fluorescence microscopy of chimeric fusions of yellow fluorescent protein (YFP with polyQ (Q40 expressed in the body wall muscle cells of Caenorhabditis elegans nematodes (1 day old adult hermaphrodites revealed diffuse and foci patterns of Q40-YFP that were both fluorescent and exhibited stronger CARS (1657 cm(-1 signals than in surrounding tissues at the resonance for the cross β-sheet polyQ in vitro.

  4. High-order Stokes and anti-Stokes Raman generation in monoisotopic CVD {sup 12}C-diamond

    Energy Technology Data Exchange (ETDEWEB)

    Kaminskii, Alexander A. [Institute of Crystallography, Russian Academy of Sciences, Moscow (Russian Federation); Lux, Oliver; Rhee, Hanjo; Eichler, Hans J. [Institute of Optics and Atomic Physics, Technische Universitaet Berlin (Germany); Ralchenko, Victor G.; Bolshakov, Andrey P. [General Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation); Shirakawa, Akira; Yoneda, Hitoki [Institute for Laser Science, University of Electro-Communications, Tokyo (Japan)

    2016-06-15

    We determined, for the first time, the room temperature phonon energy related to the F{sub 2g} vibration mode (ω{sub SRS(12C)} ∝ 1333.2 cm{sup -1}) in a mono-crystalline single-isotope CVD {sup 12}C-diamond crystal by means of stimulated Raman scattering (SRS) spectroscopy. Picosecond one-micron excitation using a Nd{sup 3+}:Y{sub 3}Al{sub 5}O{sub 12}-laser generates a nearly two-octave spanning SRS frequency comb (∝12000 cm{sup -1}) consisting of higher-order Stokes and anti-Stokes components. The spacing of the spectral lines was found to differ by Δω{sub SRS} ∝ 0.9 cm{sup -1} from the comb spacing (ω{sub SRS(natC)} ∝ 1332.3 cm{sup -1}) when pumping a conventional CVD diamond crystal with a natural composition of the two stable carbon isotopes {sup 12}C (98.93%) and {sup 13}C (1.07%). (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Detecting polymeric nanoparticles with coherent anti-stokes Raman scattering microscopy in tissues exhibiting fixative-induced autofluorescence

    Science.gov (United States)

    Garrett, N. L.; Godfrey, L.; Lalatsa, A.; Serrano, D. R.; Uchegbu, I. F.; Schatzlein, A.; Moger, J.

    2015-03-01

    Recent advances in pharmaceutical nanotechnology have enabled the development of nano-particulate medicines with enhanced drug performance. Although the fate of these nano-particles can be macroscopically tracked in the body (e.g. using radio-labeling techniques), there is little information about the sub-cellular scale mechanistic processes underlying the particle-tissue interactions, or how these interactions may correlate with pharmaceutical efficacy. To rationally engineer these nano-particles and thus optimize their performance, these mechanistic interactions must be fully understood. Coherent Anti-Stokes Raman scattering (CARS) microscopy provides a label-free means for visualizing biological samples, but can suffer from a strong non-resonant background in samples that are prepared using aldehyde-based fixatives. We demonstrate how formalin fixative affects the detection of polymeric nanoparticles within kidneys following oral administration using CARS microscopy, compared with samples that were snap-frozen. These findings have implications for clinical applications of CARS for probing nanoparticle distribution in tissue biopsies.

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

    Directory of Open Access Journals (Sweden)

    Mitra Ranjana

    2012-11-01

    Full Text Available Abstract Background 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. Methods 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. Results 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 Conclusions 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.

  7. Pressure measurements using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering.

    Science.gov (United States)

    Kearney, Sean P; Danehy, Paul M

    2015-09-01

    We investigate the feasibility of gas-phase pressure measurements using fs/ps rotational CARS. Femtosecond pump and Stokes pulses impulsively prepare a rotational Raman coherence, which is probed by a high-energy 5-ps pulse introduced at a time delay from the Raman preparation. These ultrafast laser pulses are shorter than collisional-dephasing time scales, enabling a new hybrid time- and frequency-domain detection scheme for pressure. Single-laser-shot rotational CARS spectra were recorded from N2 contained in a room-temperature gas cell for pressures from 0.4 to 3 atm and probe delays ranging from 16 to 298 ps. Sensitivity of the accuracy and precision of the pressure data to probe delay was investigated. The technique exhibits superior precision and comparable accuracy to previous laser-diagnostic pressure measurements. PMID:26368717

  8. Coherent Anti-Stokes Raman Scattering Spectroscopy of Single Molecules in Solution

    Energy Technology Data Exchange (ETDEWEB)

    Sunney Xie, Wei Min, Chris Freudiger, Sijia Lu

    2012-01-18

    During this funding period, we have developed two breakthrough techniques. The first is stimulated Raman scattering microscopy, providing label-free chemical contrast for chemical and biomedical imaging based on vibrational spectroscopy. Spontaneous Raman microscopy provides specific vibrational signatures of chemical bonds, but is often hindered by low sensitivity. We developed a three-dimensional multiphoton vibrational imaging technique based on stimulated Raman scattering (SRS). The sensitivity of SRS imaging is significantly greater than that of spontaneous Raman microscopy, which is achieved by implementing high-frequency (megahertz) phase-sensitive detection. SRS microscopy has a major advantage over previous coherent Raman techniques in that it offers background-free and readily interpretable chemical contrast. We demonstrated a variety of biomedical applications, such as differentiating distributions of omega-3 fatty acids and saturated lipids in living cells, imaging of brain and skin tissues based on intrinsic lipid contrast, and monitoring drug delivery through the epidermis. This technology offers exciting prospect for medical imaging. The second technology we developed is stimulated emission microscopy. Many chromophores, such as haemoglobin and cytochromes, absorb but have undetectable fluorescence because the spontaneous emission is dominated by their fast non-radiative decay. Yet the detection of their absorption is difficult under a microscope. We use stimulated emission, which competes effectively with the nonradiative decay, to make the chromophores detectable, as a new contrast mechanism for optical microscopy. We demonstrate a variety of applications of stimulated emission microscopy, such as visualizing chromoproteins, non-fluorescent variants of the green fluorescent protein, monitoring lacZ gene expression with a chromogenic reporter, mapping transdermal drug distribu- tions without histological sectioning, and label-free microvascular

  9. In vivo lipid saturation study of C. elegans using quantitative broadband coherent anti-Stokes Raman imaging (Conference Presentation)

    Science.gov (United States)

    Littleton, Bradley; Kavanagh, Thomas; Nie, Yu; Abbate, Vincenzo; Hylands, Peter; Sturzenbaum, Stephen; Richards, David

    2016-03-01

    In vivo lipid saturation maps of microscopic nematodes (Caenorhabditis elegans) have been produced using our novel Spectral Interferometric Polarisation Coherent anti-Stokes Raman Scattering (SIP-CARS) imaging technique. This technique employs simple passive polarisation optics and a balanced homodyne detection scheme to exploit symmetries in the CARS polarisation response resulting in the complete cancellation of the non-resonant background (NRB) and real component of the CARS signal (with no prior or post assumptions as regards to their form). The remaining imaginary component of the CARS response is linear with analyte concentration and directly relatable to the spontaneous Raman spectrum [1]. Furthermore, the resonant CARS signal is interferometrically amplified by the non-resonant response, a necessity for rapid imaging at biologically relevant powers [2]. This technique permits acquisition of a broad NRB-free spectrum, in excess of 1800cm-1, in a single exposure at each pixel. This allows simultaneous determination of lipid droplet saturation, from the fingerprint region, and lipid order, from the C-H stretch region from which maps can be readily constructed. Additionally exploiting the dispersive nature of our signal collection two-photon autofluorescence can be isolated and images subsequently produced. We have successfully applied this technique to identify differences in lipid saturation distributions in selective C. elegans mutants and demonstrated that the technique is sufficiently sensitive to detect the effects of lipid metabolism altering drugs on wild type C. elegans. [1] Littleton et al, Phys Rev Lett, 111, 103902 (2013) [2] Parekh et al, Biophys J, 99, 2695-2704 (2010)

  10. Experimental demonstration of mode-selective phonon excitation of 6H-SiC by a mid-infrared laser with anti-Stokes Raman scattering spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, Kyohei; Hachiya, Kan; Okumura, Kensuke; Mishima, Kenta; Inukai, Motoharu; Torgasin, Konstantin; Omer, Mohamed [Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Sonobe, Taro [Kyoto University Research Administration Office, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501 (Japan); Zen, Heishun; Negm, Hani; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki [Institute of Advanced Energy, Kyoto University, Gokasyo, Uji, Kyoto 611-0011 (Japan)

    2013-10-28

    Mode-selective phonon excitation by a mid-infrared laser (MIR-FEL) is demonstrated via anti-Stokes Raman scattering measurements of 6H-silicon carbide (SiC). Irradiation of SiC with MIR-FEL and a Nd-YAG laser at 14 K produced a peak where the Raman shift corresponds to a photon energy of 119 meV (10.4 μm). This phenomenon is induced by mode-selective phonon excitation through the irradiation of MIR-FEL, whose photon energy corresponds to the photon-absorption of a particular phonon mode.

  11. Dynamical study of the water penetration process into a cellulose acetate film studied by coherent anti-Stokes Raman scattering (CARS) microspectroscopy

    Science.gov (United States)

    Fujisawa, Rie; Ohno, Tomoya; Kaneyasu, Junya F.; Leproux, Philippe; Couderc, Vincent; Kita, Hiroshi; Kano, Hideaki

    2016-07-01

    The penetration process of water into a cellulose acetate film was traced in real time by coherent anti-Stokes Raman scattering (CARS) microspectroscopy. The Cdbnd O stretch mode was red-shifted due to hydrogen-bond formation. We also found that two Raman bands at 1605 cm-1 and 1665 cm-1 emerged only in the early stage of the water penetration process. Based on the combined analysis of the experimental and computational studies, these bands at 1605 cm-1 and 1665 cm-1 were assigned as the OH bend mode due to hydrogen-bonded penetrated water and hydrogen-bonded OH groups in pyranose rings, respectively.

  12. Raman and coherent anti-Stokes Raman scattering microscopy studies of changes in lipid content and composition in hormone-treated breast and prostate cancer cells

    Science.gov (United States)

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

    2014-11-01

    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.

  13. Anti-Stokes Resonance Raman of Ir Illuminated Dendrimer Iron (III)-Porphyrins%红外辐照下树枝状铁(iii)卟啉的反斯托克斯共振拉曼

    Institute of Scientific and Technical Information of China (English)

    MO Yu-jun; D.L.Jiang; M.Uymura; T.Aida; T.Kitagawa

    2005-01-01

    The benzene dendrimers of Fe(Ⅲ) tetraphenyl porphyrin chloride[LnFe(Ⅲ)TPPCl] with n = 3, 4, and 5 (n: number of layers) have been synthesized and the IR illumination effects at benzene bands were examined with anti- Stokes resonance Raman speetroseopy for their dioxane solutions.Boltzman temperatures were determined from the Stokes to anti - Stokes intensity ratio for the speetra excited at 413.1 nm in the presence and absence of IR illumination.

  14. Application of a backside-illuminated charge-coupled-device camera for single-pulse coherent anti-Stokes Raman spectroscopy N(2) thermometry.

    Science.gov (United States)

    Plath, I; Meier, W; Stricker, W

    1992-01-01

    The application of an unintensified backside-illuminated CCD for the acquisition of broadband single-pulse coherent anti-Stokes Raman spectroscopy (CARS) spectra is demonstrated. This CCD shows a quantum efficiency 5 times higher than a front-illuminated CCD and offers significant advantages compared with intensified linear photodiode array detectors generally used for single-pulse CARS thermometry. It overcomes the main drawbacks of the intensified linear photodiode array detector in single-pulse CARS N(2) spectroscopy: nonlinearity, limited dynamic range, and image persistence. A method for extending the dynamic range is demonstrated in a highly turbulent flame. PMID:19784236

  15. Application of a backside-illuminated charge-coupled-device camera for single-pulse coherent anti-Stokes Raman spectroscopy N2 thermometry

    Science.gov (United States)

    Plath, I.; Meier, W.; Stricker, W.

    1992-01-01

    The application of an unintensified backside-illuminated CCD for the acquisition of broadband single-pulse coherent anti-Stokes Raman spectroscopy (CARS) spectra is demonstrated. This CCD shows a quantum efficiency 5 times higher than a front-illuminated CCD and offers significant advantages compared with intensified linear photodiode array detectors generally used for single-pulse CARS thermometry. It overcomes the main drawbacks of the intensified linear photodiode array detector in single-pulse CARS N2 spectroscopy: nonlinearity, limited dynamic range, and image persistence. A method for extending the dynamic range is demonstrated in a highly turbulent flame.

  16. Interference-free gas-phase thermometry at elevated pressure using hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering.

    Science.gov (United States)

    Miller, Joseph D; Dedic, Chloe E; Roy, Sukesh; Gord, James R; Meyer, Terrence R

    2012-02-27

    Rotational-level-dependent dephasing rates and nonresonant background can lead to significant uncertainties in coherent anti-Stokes Raman scattering (CARS) thermometry under high-pressure, low-temperature conditions if the gas composition is unknown. Hybrid femtosecond/picosecond rotational CARS is employed to minimize or eliminate the influence of collisions and nonresonant background for accurate, frequency-domain thermometry at elevated pressure. The ability to ignore these interferences and achieve thermometric errors of <5% is demonstrated for N2 and O2 at pressures up to 15 atm. Beyond 15 atm, the effects of collisions cannot be ignored but can be minimized using a short probe delay (~6.5 ps) after Raman excitation, thereby improving thermometric accuracy with a time- and frequency-resolved theoretical model. PMID:22418304

  17. Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering at flame temperatures using a second-harmonic bandwidth-compressed probe.

    Science.gov (United States)

    Kearney, Sean P; Scoglietti, Daniel J

    2013-03-15

    We demonstrate an approach for picosecond probe-beam generation that enables hybrid femtosecond/picosecond pure-rotational coherent anti-Stokes Raman scattering (CARS) measurements in flames. Sum-frequency generation of bandwidth-compressed picosecond radiation from femtosecond pumps with phase-conjugate chirps provides probe pulses with energies in excess of 1 mJ that are temporally locked to the femtosecond pump/Stokes preparation. This method overcomes previous limitations on hybrid femtosecond/picosecond rotational CARS techniques, which have relied upon less efficient bandwidth-reduction processes that have generally resulted in prohibitively low probe energy for flame measurements. We provide the details of the second-harmonic approach and demonstrate the technique in near-adiabatic hydrogen/air flames. PMID:23503231

  18. Theoretical and experimental investigations of coherent phonon dynamics in sapphire crystal using femtosecond time-resolved coherent anti-Stokes Raman scattering

    Institute of Scientific and Technical Information of China (English)

    Du Xin; Zhang Ming-Fu; He Xing; Meng Qing-Kun; Song Yun-Fei; Yang Yan-Qiang; Han Jie-Cai

    2011-01-01

    We report on the theoretical and the experimental investigations of the coherent phonon dynamics in sapphire crystal using the femtosecond time-resolved coherent anti-Stokes Raman scattering (fs-CARS) technique.The temporal chirped white-light continuum (WLC) is used for the Stokes pulse,therefore we can perform the selective excitation of the phonon modes without using a complicated laser system.The expected quantum beat phenomenon is clearly observed.The theoretical formulas consist very well with the experimental results.The dephasing times of the excited phonon modes,the wavenumber difference,and the phase shift between the simultaneously excited modes are obtained and discussed.This work opens up a way to study directly high-frequency coherent phonon dynamics in bulk crystals on a femtosecond time scale and is especially helpful for understanding the nature of coherent phonons.

  19. The manipulation of massive ro-vibronic superpositions using time-frequency-resolved coherent anti-Stokes Raman scattering (TFRCARS) from quantum control to quantum computing

    CERN Document Server

    Zadoyan, R; Lidar, D A; Apkarian, V A

    2001-01-01

    Molecular ro-vibronic coherences, joint energy-time distributions of quantum amplitudes, are selectively prepared, manipulated, and imaged in Time-Frequency-Resolved Coherent Anti-Stokes Raman Scattering (TFRCARS) measurements using femtosecond laser pulses. The studies are implemented in iodine vapor, with its thermally occupied statistical ro-vibrational density serving as initial state. The evolution of the massive ro-vibronic superpositions, consisting of 1000 eigenstates, is followed through two-dimensional images. The first- and second-order coherences are captured using time-integrated frequency-resolved CARS, while the third-order coherence is captured using time-gated frequency-resolved CARS. The Fourier filtering provided by time integrated detection projects out single ro-vibronic transitions, while time-gated detection allows the projection of arbitrary ro-vibronic superpositions from the coherent third-order polarization. Beside the control and imaging of chemistry, the controlled manipulation of...

  20. 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;

    2015-01-01

    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......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...... conditions in the human duodenum. Both preparation method and lipid excipient affected the lysozyme distribution and release from SLMs. Lysozyme resided in a hollow core within the SLMs when incorporated as an aqueous solution. In contrast, lysozyme incorporated as a solid was embedded in clusters in the...

  1. In planta imaging of Δ9-tetrahydrocannabinolic acid in Cannabis sativa L. with hyperspectral coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

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

    2013-04-01

    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.

  2. Three-pulse multiplex coherent anti-Stokes/Stokes Raman scattering (CARS/CSRS) microspectroscopy using a white-light laser source

    International Nuclear Information System (INIS)

    Highlights: ► We have developed a simultaneous measurement system of CARS and CSRS. ► We can obtain information on the electronic resonance effect with the measurement. ► The simultaneous measurement provides us with more reliable spectral information. - Abstract: We have developed a three-pulse non-degenerate multiplex coherent Raman microspectroscopic system using a white-light laser source. The fundamental output (1064 nm) of a Nd:YAG laser is used for the pump radiation with the white-light laser output (1100–1700 nm) for the Stokes radiation to achieve broadband multiplex excitations of vibrational coherences. The second harmonic (532 nm) of the same Nd:YAG laser is used for the probe radiation. Thanks to the large wavelength difference between the pump and probe radiations, coherent anti-Stokes Raman scattering (CARS) and coherent Stokes Raman scattering (CSRS) can be detected simultaneously. Simultaneous detection of CARS and CSRS enables us to obtain information on the electronic resonance effect that affects differently the CARS and CSRS signals. Simultaneous analysis of the CARS and CSRS signals provides us the imaginary part of χ(3) without introducing any arbitrary parameter in the maximum entropy method (MEM)

  3. Probe-pulse optimization for nonresonant suppression in hybrid fs/ps coherent anti-Stokes Raman scattering at high temperature.

    Science.gov (United States)

    Miller, Joseph D; Slipchenko, Mikhail N; Meyer, Terrence R

    2011-07-01

    Hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) offers accurate thermometry at kHz rates for combustion diagnostics. In high-temperature flames, selection of probe-pulse characteristics is key to simultaneously optimizing signal-to-nonresonant-background ratio, signal strength, and spectral resolution. We demonstrate a simple method for enhancing signal-to-nonresonant-background ratio by using a narrowband Lorentzian filter to generate a time-asymmetric probe pulse with full-width-half-maximum (FWHM) pulse width of only 240 fs. This allows detection within just 310 fs after the Raman excitation for eliminating nonresonant background while retaining 45% of the resonant signal at 2000 K. The narrow linewidth is comparable to that of a time-symmetric sinc2 probe pulse with a pulse width of ~2.4 ps generated with a conventional 4-f pulse shaper. This allows nonresonant-background-free, frequency-domain vibrational spectroscopy at high temperature, as verified using comparisons to a time-dependent theoretical fs/ps CARS model. PMID:21747487

  4. Implementation of a Coherent Anti-Stokes Raman Scattering (CARS) System on a Ti:Sapphire and OPO Laser Based Standard Laser Scanning Microscope.

    Science.gov (United States)

    Mytskaniuk, Vasyl; Bardin, Fabrice; Boukhaddaoui, Hassan; Rigneault, Herve; Tricaud, Nicolas

    2016-01-01

    Laser scanning microscopes combining a femtosecond Ti:sapphire laser and an optical parametric oscillator (OPO) to duplicate the laser line have become available for biologists. These systems are primarily designed for multi-channel two-photon fluorescence microscopy. However, without any modification, complementary non-linear optical microscopy such as second-harmonic generation (SHG) or third harmonic generation (THG) can also be performed with this set-up, allowing label-free imaging of structured molecules or aqueous medium-lipid interfaces. These techniques are well suited for in-vivo observation, but are limited in chemical specificity. Chemically selective imaging can be obtained from inherent vibration signals based on Raman scattering. Confocal Raman microscopy provides 3D spatial resolution, but it requires high average power and long acquisition time. To overcome these difficulties, recent advances in laser technology have permitted the development of nonlinear optical vibrational microscopy, in particular coherent anti-Stokes Raman scattering (CARS). CARS microscopy has therefore emerged as a powerful tool for biological and live cell imaging, by chemically mapping lipids (via C-H stretch vibration), water (via O-H stretch vibrations), proteins or DNA. In this work, we describe the implementation of the CARS technique on a standard OPO-coupled multiphoton laser scanning microscope. It is based on the in-time synchronization of the two laser lines by adjusting the length of one of the laser beam path. We present a step-by-step implementation of this technique on an existing multiphoton system. A basic background in experimental optics is helpful and the presented system does not require expensive supplementary equipment. We also illustrate CARS imaging obtained on myelin sheaths of sciatic nerve of rodent, and we show that this imaging can be performed simultaneously with other nonlinear optical imaging, such as standard two-photon fluorescence technique

  5. Multimodal coherent anti-Stokes Raman scattering microscopy reveals microglia-associated myelin and axonal dysfunction in multiple sclerosis-like lesions in mice

    Science.gov (United States)

    Imitola, Jaime; Côté, Daniel; Rasmussen, Stine; Xie, X. Sunney; Liu, Yingru; Chitnis, Tanuja; Sidman, Richard L.; Lin, Charles. P.; Khoury, Samia J.

    2011-02-01

    Myelin loss and axonal degeneration predominate in many neurological disorders; however, methods to visualize them simultaneously in live tissue are unavailable. We describe a new imaging strategy combining video rate reflectance and fluorescence confocal imaging with coherent anti-Stokes Raman scattering (CARS) microscopy tuned to CH2 vibration of myelin lipids, applied in live tissue of animals with chronic experimental autoimmune encephalomyelitis (EAE). Our method allows monitoring over time of demyelination and neurodegeneration in brain slices with high spatial resolution and signal-to-noise ratio. Local areas of severe loss of lipid signal indicative of demyelination and loss of the reflectance signal from axons were seen in the corpus callosum and spinal cord of EAE animals. Even in myelinated areas of EAE mice, the intensity of myelin lipid signals is significantly reduced. Using heterozygous knock-in mice in which green fluorescent protein replaces the CX3CR1 coding sequence that labels central nervous system microglia, we find areas of activated microglia colocalized with areas of altered reflectance and CARS signals reflecting axonal injury and demyelination. Our data demonstrate the use of multimodal CARS microscopy for characterization of demyelinating and neurodegenerative pathology in a mouse model of multiple sclerosis, and further confirm the critical role of microglia in chronic inflammatory neurodegeneration.

  6. Single-shot gas-phase thermometry using pure-rotational hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering

    Science.gov (United States)

    Miller, Joseph D.; Roy, Sukesh; Slipchenko, Mikhail N.; Gord, James R.; Meyer, Terrence R.

    2011-08-01

    High-repetition-rate, single-laser-shot measurements are important for the investigation of unsteady flows where temperature and species concentrations can vary significantly. Here, we demonstrate single-shot, pure-rotational, hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps RCARS) thermometry based on a kHz-rate fs laser source. Interferences that can affect nanosecond (ns) and ps CARS, such as nonresonant background and collisional dephasing, are eliminated by selecting an appropriate time delay between the 100-fs pump/Stokes pulses and the pulse-shaped 8.4-ps probe. A time- and frequency-domain theoretical model is introduced to account for rotational-level dependent collisional dephasing and indicates that the optimal probe-pulse time delay is 13.5 ps to 30 ps. This time delay allows for uncorrected best-fit N2-RCARS temperature measurements with ~1% accuracy. Hence, the hybrid fs/ps RCARS approach can be performed with kHz-rate laser sources while avoiding corrections that can be difficult to predict in unsteady flows.

  7. Impact of refractive index mismatches on coherent anti-Stokes Raman scattering and multiphoton autofluorescence tomography of human skin in vivo

    International Nuclear Information System (INIS)

    Optical non-linear multimodal tomography is a powerful diagnostic imaging tool to analyse human skin based on its autofluorescence and second-harmonic generation signals. Recently, the field of clinical non-linear imaging has been extended by adding coherent anti-Stokes Raman scattering (CARS)—a further optical sectioning method for the detection of non-fluorescent molecules. However, the heterogeneity of refractive indices of different substances in complex tissues like human skin can have a strong influence on CARS image formation and requires careful clinical interpretation of the detected signals. Interestingly, very regular patterns are present in the CARS images, which have no correspondence to the morphology revealed by autofluorescence at the same depth. The purpose of this paper is to clarify this phenomenon and to sensitize users for possible artefacts. A further part of this paper is the detailed comparison of CARS and autofluorescence images of healthy human skin in vivo covering the complete epidermis and part of the upper dermis by employing the flexible medical non-linear tomograph MPTflex CARS. (paper)

  8. Lipid droplet pattern and nondroplet-like structure in two fat mutants of Caenorhabditis elegans revealed by coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

    Yi, Yung-Hsiang; Chien, Cheng-Hao; Chen, Wei-Wen; Ma, Tian-Hsiang; Liu, Kuan-Yu; Chang, Yu-Sun; Chang, Ta-Chau; Lo, Szecheng J.

    2014-01-01

    Lipid is an important energy source and essential component for plasma and organelle membranes in all kinds of cells. Coherent anti-Stokes Raman scattering (CARS) microscopy is a label-free and nonlinear optical technique that can be used to monitor the lipid distribution in live organisms. Here, we utilize CARS microscopy to investigate the pattern of lipid droplets in two live Caenorhabditis elegans mutants (fat-2 and fat-3). The CARS images showed a striking decrease in the size, number, and content of lipid droplets in the fat-2 mutant but a slight difference in the fat-3 mutant as compared with the wild-type worm. Moreover, a nondroplet-like structure with enhanced CARS signal was detected for the first time in the uterus of fat-2 and fat-3 mutants. In addition, transgenic fat-2 mutant expressing a GFP fusion protein of vitellogenin-2 (a yolk lipoprotein) revealed that the enhanced CARS signal colocalized with the GFP signal, which suggests that the nondroplet-like structure is primarily due to the accumulation of yolk lipoproteins. Together, this study implies that CARS microscopy is a potential tool to study the distribution of yolk lipoproteins, in addition to lipid droplets, in live animals.

  9. 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: sooying@ntu.edu.sg [Division of Physics & Applied Physics, and Division of Chemistry & Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore)

    2015-12-15

    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.

  10. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    Institute of Scientific and Technical Information of China (English)

    Yin Jun; Yu Ling-Yao; Liu Xing; Wan Hui; Lin Zi-Yang; Niu Han-Ben

    2011-01-01

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of verious molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactious in the fields of biology, chemistry and naterial science.

  11. Simultaneous measurements of global vibrational spectra and dephasing times of molecular vibrational modes by broadband time-resolved coherent anti-Stokes Raman scattering spectrography

    International Nuclear Information System (INIS)

    In broadband coherent anti-Stokes Raman scattering (CARS) spectroscopy with supercontinuum (SC), the simultaneously detectable spectral coverage is limited by the spectral continuity and the simultaneity of various spectral components of SC in an enough bandwidth. By numerical simulations, the optimal experimental conditions for improving the SC are obtained. The broadband time-resolved CARS spectrography based on the SC with required temporal and spectral distributions is realised. The global molecular vibrational spectrum with well suppressed nonresonant background noise can be obtained in a single measurement. At the same time, the measurements of dephasing times of various molecular vibrational modes can be conveniently achieved from intensities of a sequence of time-resolved CARS signals. It will be more helpful to provide a complete picture of molecular vibrations, and to exhibit a potential to understand not only both the solvent dynamics and the solute-solvent interactions, but also the mechanisms of chemical reactions in the fields of biology, chemistry and material science. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

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

    Directory of Open Access Journals (Sweden)

    Kai Niu

    2015-12-01

    Full Text Available 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.

  13. Label-free assessment of adipose-derived stem cell differentiation using coherent anti-Stokes Raman scattering and multiphoton microscopy

    Science.gov (United States)

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

    2012-11-01

    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.

  14. Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy

    OpenAIRE

    Evans, Conor L.; Potma, Eric O.; Puoris'haag, Mehron; Côté, Daniel; Lin, Charles P.; Xie, X. Sunney

    2005-01-01

    Imaging living organisms with molecular selectivity typically requires the introduction of specific labels. Many applications in biology and medicine, however, would significantly benefit from a noninvasive imaging technique that circumvents such exogenous probes. In vivo microscopy based on vibrational spectroscopic contrast offers a unique approach for visualizing tissue architecture with molecular specificity. We have developed a sensitive technique for vibrational imaging of tissues by co...

  15. Time- and frequency-dependent model of time-resolved coherent anti-Stokes Raman scattering (CARS) with a picosecond-duration probe pulse

    Science.gov (United States)

    Stauffer, Hans U.; Miller, Joseph D.; Slipchenko, Mikhail N.; Meyer, Terrence R.; Prince, Benjamin D.; Roy, Sukesh; Gord, James R.

    2014-01-01

    The hybrid femtosecond/picosecond coherent anti-Stokes Raman scattering (fs/ps CARS) technique presents a promising alternative to either fs time-resolved or ps frequency-resolved CARS in both gas-phase thermometry and condensed-phase excited-state dynamics applications. A theoretical description of time-dependent CARS is used to examine this recently developed probe technique, and quantitative comparisons of the full time-frequency evolution show excellent accuracy in predicting the experimental vibrational CARS spectra obtained for two model systems. The interrelated time- and frequency-domain spectral signatures of gas-phase species produced by hybrid fs/ps CARS are explored with a focus on gas-phase N2 vibrational CARS, which is commonly used as a thermometric diagnostic of combusting flows. In particular, we discuss the merits of the simple top-hat spectral filter typically used to generate the ps-duration hybrid fs/ps CARS probe pulse, including strong discrimination against non-resonant background that often contaminates CARS signal. It is further demonstrated, via comparison with vibrational CARS results on a time-evolving solvated organic chromophore, that this top-hat probe-pulse configuration can provide improved spectral resolution, although the degree of improvement depends on the dephasing timescales of the observed molecular modes and the duration and timing of the narrowband final pulse. Additionally, we discuss the virtues of a frequency-domain Lorentzian probe-pulse lineshape and its potential for improving the hybrid fs/ps CARS technique as a diagnostic in high-pressure gas-phase thermometry applications.

  16. Hybrid femtosecond/picosecond rotational coherent anti-Stokes Raman scattering temperature and concentration measurements using two different picosecond-duration probes.

    Science.gov (United States)

    Kearney, Sean P; Scoglietti, Daniel J; Kliewer, Christopher J

    2013-05-20

    A hybrid fs/ps pure-rotational CARS scheme is characterized in furnace-heated air at temperatures from 290 to 800 K. Impulsive femtosecond excitation is used to prepare a rotational Raman coherence that is probed with a ps-duration beam generated from an initially broadband fs pulse that is bandwidth limited using air-spaced Fabry-Perot etalons. CARS spectra are generated using 1.5- and 7.0-ps duration probe beams with corresponding coarse and narrow spectral widths. The spectra are fitted using a simple phenomenological model for both shot-averaged and single-shot measurements of temperature and oxygen mole fraction. Our single-shot temperature measurements exhibit high levels of precision and accuracy when the spectrally coarse 1.5-ps probe beam is used, demonstrating that high spectral resolution is not required for thermometry. An initial assessment of concentration measurements in air is also provided, with best results obtained using the higher resolution 7.0-ps probe. This systematic assessment of the hybrid CARS technique demonstrates its utility for practical application in low-temperature gas-phase systems. PMID:23736451

  17. Raman Spectroscopic Studies of Methane Gas Hydrates

    DEFF Research Database (Denmark)

    Hansen, Susanne Brunsgaard; Berg, Rolf W.

    2009-01-01

    A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory.......A brief review of the Raman spectroscopic studies of methane gas hydrates is given, supported by some new measurements done in our laboratory....

  18. Observation of anomalous Stokes versus anti-Stokes ratio in MoTe2 atomic layers

    Science.gov (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).

  19. Raman spectroscopic studies on bacteria

    Science.gov (United States)

    Maquelin, Kees; Choo-Smith, Lin-P'ing; Endtz, Hubert P.; Bruining, Hajo A.; Puppels, Gerwin J.

    2000-11-01

    Routine clinical microbiological identification of pathogenic micro-organisms is largely based on nutritional and biochemical tests. Laboratory results can be presented to a clinician after 2 - 3 days for most clinically relevant micro- organisms. Most of this time is required to obtain pure cultures and enough biomass for the tests to be performed. In the case of severely ill patients, this unavoidable time delay associated with such identification procedures can be fatal. A novel identification method based on confocal Raman microspectroscopy will be presented. With this method it is possible to obtain Raman spectra directly from microbial microcolonies on the solid culture medium, which have developed after only 6 hours of culturing for most commonly encountered organisms. Not only does this technique enable rapid (same day) identifications, but also preserves the sample allowing it to be double-checked with traditional tests. This, combined with the speed and minimal sample handling indicate that confocal Raman microspectroscopy has much potential as a powerful new tool in clinical diagnostic microbiology.

  20. Mapping the energy distribution of SERRS hot spots from anti-Stokes to Stokes intensity ratios.

    Science.gov (United States)

    dos Santos, Diego P; Temperini, Marcia L A; Brolo, Alexandre G

    2012-08-15

    The anomalies in the anti-Stokes to Stokes intensity ratios in single-molecule surface-enhanced resonance Raman scattering were investigated. Brilliant green and crystal violet dyes were the molecular probes, and the experiments were carried out on an electrochemically activated Ag surface. The results allowed new insights into the origin of these anomalies and led to a new method to confirm the single-molecule regime in surface-enhanced Raman scattering. Moreover, a methodology to estimate the distribution of resonance energies that contributed to the imbalance in the anti-Stokes to Stokes intensity ratios at the electromagnetic hot spots was proposed. This method allowed the local plasmonic resonance energies on the metallic surface to be spatially mapped. PMID:22804227

  1. Raman Spectroscopic Study on Phosphorous-Doped Silicon Nanoparticles.

    Science.gov (United States)

    Momose, Miho; Hirasaka, Masao; Furukawa, Yukio

    2015-07-01

    The Raman spectra of films prepared from 8, 19, and 30 nm nanoparticles of silicon doped with phosphorous were measured with excitation at 514.5 nm. The observed spectra were analyzed by decomposing the observed Raman bands into three symmetric Voigt function bands, which were assigned to the Si-Si stretching modes of crystalline, boundary, and amorphous-like components. The fractions of crystalline, boundary, and amorphous-like regions were estimated from the obtained components. The obtained fractions can be explained as a sphere-like nanoparticle consisting of a crystalline core surrounded with boundary and amorphous-like shells, which is consistent with the transmission electron microscope images showing a sphere-like shape. The observed spectral shape of the 8 nm nanoparticle film showed significant changes upon light irradiation with a power density of 5.5 kW cm(-2), i.e., the amorphous-like region converted to a crystalline one. The temperature of the film under laser irradiation was estimated to be lower than 1041 °C from the anti-Stokes to the Stokes Raman bands due to the Si-Si stretching mode. The observed partial crystallization is probably induced by heating associated with light irradiation. PMID:26036307

  2. Raman and mid-infrared spectroscopic imaging: applications and advancements

    NARCIS (Netherlands)

    Gautam, R.; Samuel, A.; Sil, S.; Chaturvedi, D.; Dutta, A.; Ariese, F.; Umapathy, S.

    2015-01-01

    Using Raman and Mid-Infrared (MIR) spectroscopic imaging techniques one can examine the spatial distribution of various molecular constituents in a heterogeneous sample at a microscopic scale. Raman and MIR spectroscopy techniques provide bond-specific vibrational frequencies to characterize molecul

  3. Raman and surface enhanced Raman spectroscopic investigation on Lamiaceae plants

    Science.gov (United States)

    Rösch, P.; Popp, J.; Kiefer, W.

    1999-05-01

    The essential oils of Thymus vulgaris and Origanum vulgaris are studied by means of micro-Raman spectroscopy. The containing monoterpenes can be identified by their Raman spectra. Further the essential oils are investigated in their natural environment, the so-called oil cells of these Lamiaceae plants, with surface enhanced Raman spectroscopy (SERS). This method has the advantage to enhance Raman signals and furthermore the SERS effect leads to fluorescence quenching.

  4. 在Na2(A1∑_u+)与H2碰撞中的相干反斯托克斯拉曼谱研究%Coherent Anti-Stokes Raman Spectroscopy Study in the Na2(A1∑_u~+)-H2 Collision

    Institute of Scientific and Technical Information of China (English)

    蔡勤; 张利平; 栾楠楠; 程玉锋; 戴康; 沈异凡

    2011-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) has been used to analyze the internal state distribution of H2 after energy transfer with Na2 (A1 S,f ). The scanned CARS reveals that during energy transfer processes H2 molecules are produced at the V=l, 2 and 3 vibrational levels. Two possible populations ratios (w,/ra2) are obtained from scanned CARS peaks. The actual population ratio Hi/n2 is determined to be 1. 82 through shape simulations of the time resolved CARS profiles under a kinetic model. The n,/n2 ratio indicates that the H2 molecules produced by the energy transfer process are 0.53 populated at the V=l level, 0.30 at V=2 and 0.17 at V=3. The relative fraction (, ) of average energy disposal is derived as 0.51, 0.46, 0.03, which has a major energy releases in vibrational and translational. This consequence supports the col linear collision geometry in ratio Na2-H2 energy transfer.%利用相干反斯托克斯拉曼谱(CARS)分析了H:在与Na2(A1∑_u~+)碰撞后的振转态布居数分布.扫描CARS表明了在能量转移过程中H:在V=1,2,3振动能级上得到布居.由扫描CARS的峰值得到2个可能的布居数比值,通过解速率方程组及时间分辨CARS轮廓模拟,确定实际的布居数比n1//n2为1.82,得到了在能量转移中H2在V=1,2,3振动能级上的布居数之比为0.53:0.30:0.17.平均转移能量分配的相对值,,分别为0.51,0.46,0.03,能量主要配置在振动和平动上,支持Na2-H2的直线式碰撞传能机制.

  5. Raman spectroscopic determination of concentration dependent diffusion coefficients

    International Nuclear Information System (INIS)

    The determination of concentration dependent diffusion coefficients D(c) is possible, if two concentration profiles in a solution at short time distances are recorded by means of the Raman spectroscopic method. D(c) is elegantly obtained by application of the Boltzmann transformation in connection with Fick's second law. (author)

  6. Laser induced broad band anti-Stokes white emission from LiYbF4 nanocrystals

    Institute of Scientific and Technical Information of China (English)

    L. Marciniak; R. Tomala; M. Stefanski; D. Hreniak; W. Strek

    2016-01-01

    Spectroscopic properties of tetragonal LiYbF4 nanocrystals under high dense NIR excitation at vacuum condition were in-vestigated. White, broad band emission covering whole visible part of the spectrum from LiYbF4 nanocrystals was observed. Its in-tensity strongly depended on the excitation power, excitation wavelength and ambient pressure. Temperature of the nanocrystals un-der 975 nm excitation was determined as a function of excitation power. Strong photo-induced current was observed from LiYbF4 pallet. The emission kinetic was analyzed. The mechanism of the anti-Stokes white emission was discussed in terms of the la-ser-induced charge transfer emission from Yb2+ states.

  7. Oral cancer screening: serum Raman spectroscopic approach

    Science.gov (United States)

    Sahu, Aditi K.; Dhoot, Suyash; Singh, Amandeep; Sawant, Sharada S.; Nandakumar, Nikhila; Talathi-Desai, Sneha; Garud, Mandavi; Pagare, Sandeep; Srivastava, Sanjeeva; Nair, Sudhir; Chaturvedi, Pankaj; Murali Krishna, C.

    2015-11-01

    Serum Raman spectroscopy (RS) has previously shown potential in oral cancer diagnosis and recurrence prediction. To evaluate the potential of serum RS in oral cancer screening, premalignant and cancer-specific detection was explored in the present study using 328 subjects belonging to healthy controls, premalignant, disease controls, and oral cancer groups. Spectra were acquired using a Raman microprobe. Spectral findings suggest changes in amino acids, lipids, protein, DNA, and β-carotene across the groups. A patient-wise approach was employed for data analysis using principal component linear discriminant analysis. In the first step, the classification among premalignant, disease control (nonoral cancer), oral cancer, and normal samples was evaluated in binary classification models. Thereafter, two screening-friendly classification approaches were explored to further evaluate the clinical utility of serum RS: a single four-group model and normal versus abnormal followed by determining the type of abnormality model. Results demonstrate the feasibility of premalignant and specific cancer detection. The normal versus abnormal model yields better sensitivity and specificity rates of 64 and 80% these rates are comparable to standard screening approaches. Prospectively, as the current screening procedure of visual inspection is useful mainly for high-risk populations, serum RS may serve as a useful adjunct for early and specific detection of oral precancers and cancer.

  8. 超衍射极限相干反斯托克斯拉曼散射显微成像技术及其探测极限分析*%Diffraction barrier breakthrough in coherent anti-Stokes Raman scattering microscopy and detection limitanalysis*

    Institute of Scientific and Technical Information of China (English)

    刘伟; 陈丹妮; 刘双龙; 牛憨笨

    2013-01-01

    We provide an approach to breaking the diffraction limit in coherent anti-Stokes Raman scattering (CARS) microscopy and report a theoretical analysis of detection limit (DL) forit. The additional probe beam, whose profile is doughnut shaped and wavelength is different from the size of Gaussian probe beam, interacts with the coherent phonons at the rim of the diffraction-limited spot to increase theresolution by re-engineering the point spreadfunction of the system. The signal strength reduces with the size of focal volume decreasing, besides, when CARS is used in biology, the molecules of interest are usually in low concentration, which makes the signal detection more difficult. Accordingly, a remaining crucial problem is whether the reduced signal generated in the suppressed focal volume can be detected from the noise background and the analysis of DL, so it is an important precise in implementation of CARS nanoscopy. We describe T-CARS process with full quantum theory and estimate the extreme power density levels of the pump and Stokes beams determined by saturation behavior of coherent phonons. When the pump and Stokes intensities reach such extreme values and total intensity of the excitation beams arrives at a maximum tolerable by most biological samples in acertain suppressed focal volume, the DL of T-CARS nanoscopy correspondingly varies with the exposure time. For an attainable spatial resolution of∼40 nm in three dimension and areasonable exposure time of 20 ms, the DL in the suppressed focal volume is approximately∼103 . The signal can be well detected from the noise fluctuation only if the number of molecules of interest exceeds this limit.%  理论上提出一种突破衍射极限限制的相干反斯托克斯拉曼散射显微成像方法,并对其探测极限进行分析。通过引入环形附加探测光与艾里斑周边的声子作用,实现点扩展函数的改造,提高相干反斯托克斯拉曼散射显微成像系统的横向空间

  9. Surface enhanced Raman scattering spectroscopic waveguide

    Science.gov (United States)

    Lascola, Robert J; McWhorter, Christopher S; Murph, Simona H

    2015-04-14

    A waveguide for use with surface-enhanced Raman spectroscopy is provided that includes a base structure with an inner surface that defines a cavity and that has an axis. Multiple molecules of an analyte are capable of being located within the cavity at the same time. A base layer is located on the inner surface of the base structure. The base layer extends in an axial direction along an axial length of an excitation section. Nanoparticles are carried by the base layer and may be uniformly distributed along the entire axial length of the excitation section. A flow cell for introducing analyte and excitation light into the waveguide and a method of applying nanoparticles may also be provided.

  10. Raman spectroscopic study of leptospiral glycolipoprotein

    Science.gov (United States)

    Bao, PeiDi; Bao, Lang; Huang, TianQuan; Liu, XinMing

    1998-04-01

    The Raman scattering spectra of two different samples of Leptospiral Glycoipoprotein (GLP-1 and GLP-2) which have different toxic effects have been obtained and investigated. Leptospirosis is one of the most harmful zoonosis. It is a serious public health issue in some area of Sichusan province. The two samples offer different structural informations of GLP molecules, it would be important to find the difference in contents, structures and the amino acid side - chains environment of the molecules between the two samples of GLP for understanding the different toxic effects. The intense Am I at 1651 cm-1 and weak Am III at 1283 cm-1 show that GLP-1 has a predominantly (alpha) -helix secondary structure. The intense Am I at 1674 cm-1 and intense Am III at 1246 cm-1 show that the conformation of GLP-2 has a high content of (Beta) - sheet and a low content of random - coil secondary structure. Strong Raman scattering occurs in the range 920- 980 cm-1, belong to the C-COO vibration and the stretching of the peptide backbone. The molecules of GLP-1 has trans-gauche-trans configuration of the C-S-S-C-C linkage and the molecules of GLP-2 has trans-gauche-gauche configuration of the C-C-S-S-C-C linkage. The intensity ratio of the two tyrosine liens at 830 cm-1 and 850 cm-1 is 1.1 and 1.23, indicate their tyrosine reduces environment respectively. Other side-chain environment in the two samples were discussed.

  11. Raman spectroscopic study of a genetically altered kidney cell

    Science.gov (United States)

    Joshi, Joel; Garcia, Francisco; Centeno, Silvia P.; Joshi, N. V.

    2008-02-01

    A Raman spectroscopic investigation of a genetically altered Human Embryonic Kidney Cell (HEK293) along with a pathologically normal cell has been carried out by a conventional method. The genetic alteration was carried out with a standard protocol by using a Green Fluorescence Protein (GFP). Raman spectra show that there are dramatic differences between the spectrum obtained from a genetically altered cell and that obtained from a pathologically normal cell. The former shows three broad bands; meanwhile the latter shows several sharp peaks corresponding to the ring vibrational modes of Phen, GFP and DNA. The present analysis provides an indication that the force field near Phen located at 64, 65 and 66 was altered during the genetic transformation. The Raman spectrum could be a direct experimental evidence for substantial modifications triggered due to the expression of specific genes.

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

    DEFF Research Database (Denmark)

    Andresen, Esben Ravn

    2006-01-01

    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,...

  13. Raman spectroscopic study of "The Malatesta": a Renaissance painting?

    Science.gov (United States)

    Edwards, Howell G M; Vandenabeele, Peter; Benoy, Timothy J

    2015-02-25

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

  14. Raman spectroscopic studies of the cure of dicyclopentadiene (DCPD)

    Science.gov (United States)

    Barnes, S. E.; Brown, E. C.; Corrigan, N.; Coates, P. D.; Harkin-Jones, E.; Edwards, H. G. M.

    2005-10-01

    The cure of polydicyclopentadiene conducted by ring-opening metathesis polymerisation in the presence of a Grubbs catalyst was studied using non-invasive Raman spectroscopy. The spectra of the monomer precursor and polymerised product were fully characterised and all stages of polymerisation monitored. Because of the monomer's high reactivity, the cure process is adaptable to reaction injection moulding and reactive rotational moulding. The viscosity of the dicyclopentadiene undergoes a rapid change at the beginning of the polymerisation process and it is critical that the induction time of the viscosity increase is determined and controlled for successful manufacturing. The results from this work show non-invasive Raman spectroscopic monitoring to be an effective method for monitoring the degree of cure, paving the way for possible implementation of the technique as a method of real-time analysis for control and optimisation during reactive processing. Agreement is shown between Raman measurements and ultrasonic time of flight data acquired during the initial induction period of the curing process.

  15. On-Line Multichannel Raman Spectroscopic Detection System For Capillary Zone Electrophoresis

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    An on-line multichannel Raman spectroscopic detection system for capillary electrophoresis was established by using an Ar+ laser and a cryogenically cooled ICCD. Resonant excitation Raman spectra of methyl red and methyl orange were employed to test the system. The result shows that it could yield on-line electrophoretogram and time series of Raman spectra.

  16. Analytical Raman spectroscopic discrimination between yellow pigments of the Renaissance.

    Science.gov (United States)

    Edwards, Howell G M

    2011-10-01

    The Renaissance represented a major advance in painting techniques, subject matter, artistic style and the use of pigments and pigment mixtures. However, most pigments in general use were still mineral-based as most organic dyes were believed to be fugitive; the historical study of artists' palettes and recipes has assumed importance for the attribution of art works to the Renaissance period. Although the application of diagnostic elemental and molecular spectroscopic techniques play vital and complementary roles in the analysis of art works, elemental techniques alone cannot definitively provide the data needed for pigment identification. The advantages and limitations of Raman spectroscopy for the definitive diagnostic characterisation of yellow pigments that were in use during the Renaissance is demonstrated here in consideration of heavy metal oxides and sulphides; these data will be compared with those obtained from analyses of synthetic yellow pigments that were available during the eighteenth and nineteenth Centuries which could have been used in unrecorded restorations of Renaissance paintings.

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

    Science.gov (United States)

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

    2013-05-01

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

  18. An induction heating diamond anvil cell for high pressure and temperature micro-Raman spectroscopic measurements.

    Science.gov (United States)

    Shinoda, Keiji; Noguchi, Naoki

    2008-01-01

    A new external heating configuration is presented for high-temperature diamond anvil cell instruments. The supporting rockers are thermally excited by induction from an externally mounted copper coil passing a 30 kHz alternating current. The inductive heating configuration therefore avoids the use of breakable wires, yet is capable of cell temperatures of 1100 K or higher. The diamond anvil cell has no resistive heaters, but uses a single-turn induction coil for elevating the temperature. The induction coil is placed near the diamonds and directly heats the tungsten carbide rockers that support the diamond. The temperature in the cell is determined from a temperature-power curve calibrated by the ratio between the intensities of the Stokes and anti-Stokes Raman lines of silicon. The high-pressure transformation of quartz to coesite is successfully observed by micro-Raman spectroscopy using this apparatus. The induction heating diamond anvil cell is thus a useful alternative to resistively heated diamond anvil cells. PMID:18248060

  19. Spectroscopic ellipsometric and Raman spectroscopic investigations of pulsed laser treated glassy carbon surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Csontos, J., E-mail: jcsontos@titan.physx.u-szeged.hu [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Pápa, Z.; Gárdián, A. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Füle, M. [University of Szeged, Department of Experimental Physics, Dóm tér 9, H-6720 Szeged (Hungary); Budai, J. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); Toth, Z. [University of Szeged, Department of Optics and Quantum Electronics, Dóm tér 9, H-6720 Szeged (Hungary); University of Szeged, Department of Oral Biology and Experimental Dental Research, Tisza Lajos krt. 64, H-6720 Szeged (Hungary)

    2015-05-01

    Highlights: • Laser treatment modifies the top layer of glassy carbon as shown by ellipsometry. • Raman signal is composed from signals of the layer and the glassy carbon substrate. • Using volumetric fluence allows to compare the effects of different lasers. • Melting effects of glassy carbon was observed in case of Nd:YAG laser treatment. - Abstract: In this study spectroscopic ellipsometry (SE) and Raman spectroscopy are applied to study structural modification of glassy carbon, due to high intensity laser ablation. Two KrF lasers with different pulse durations (480 fs and 18 ns), an ArF (20 ns), and a frequency doubled Nd:YAG laser (8 ns) were applied to irradiate the surface of glassy carbon targets. The main characteristics of the different laser treatments are compared by introducing the volumetric fluence which takes into account the different absorption values at different wavelengths. SE showed the appearance of a modified layer on the ablated surfaces. In the case of the ns lasers the thickness of this layer was in the range of 10–60 nm, while in the case of fs laser it was less than 20 nm. In all cases the average refractive index (n) of the modified layers slightly decreased compared to the refractive index of glassy carbon. Increase in extinction coefficient (k) was observed in the cases of ArF and fs KrF laser treatment, while the k values decreased significantly in the cases of nanosecond pulse duration KrF and Nd:YAG laser treatments. In the Raman spectra of the ablated areas the characteristic D and G peaks were widened due to appearance of an amorphous phase. Both Raman spectroscopy and SE indicate that the irradiated areas show carbon nanoparticle formation in all cases.

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

    Science.gov (United States)

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

    2016-02-01

    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.

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

    Science.gov (United States)

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

    2016-03-01

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

  2. Raman spectroscopic investigation of urinary calculi and salivary stones

    International Nuclear Information System (INIS)

    Full text: The capabilities and limitations of determining the composition of urinary calculi (34 patients) and salivary stones (27 patients) by Raman spectroscopy have been investigated by analysing Raman spectra obtained with 1064 nm laser excitation, and comparing them with Raman spectra both from specific reference substances and from a commercial Raman database. The composition results were also compared with those obtained by other analytical methods e.g. powder diffraction. Raman spectroscopy proves to be an analytical method which provides reliable results on the composition of urinary calculi and salivary stones quickly, non-destructively and without any need of sample preparation. (author)

  3. Raman spectroscopic investigation of thorium dioxide-uranium dioxide (ThO₂-UO₂) fuel materials.

    Science.gov (United States)

    Rao, Rekha; Bhagat, R K; Salke, Nilesh P; Kumar, Arun

    2014-01-01

    Raman spectroscopic investigations were carried out on proposed nuclear fuel thorium dioxide-uranium dioxide (ThO2-UO2) solid solutions and simulated fuels based on ThO2-UO2. Raman spectra of ThO2-UO2 solid solutions exhibited two-mode behavior in the entire composition range. Variations in mode frequencies and relative intensities of Raman modes enabled estimation of composition, defects, and oxygen stoichiometry in these compounds that are essential for their application. The present study shows that Raman spectroscopy is a simple, promising analytical tool for nondestructive characterization of this important class of nuclear fuel materials.

  4. Raman and infrared spectroscopic study of turquoise minerals

    Science.gov (United States)

    Čejka, Jiří; Sejkora, Jiří; Macek, Ivo; Malíková, Radana; Wang, Lina; Scholz, Ricardo; Xi, Yunfei; Frost, Ray L.

    2015-10-01

    Raman and infrared spectra of three well-defined turquoise samples, CuAl6(PO4)4(OH)8·4H2O, from Lavender Pit, Bisbee, Cochise county, Arizona; Kouroudaiko mine, Faleme river, Senegal and Lynch Station, Virginia were studied, interpreted and compared. Observed Raman and infrared bands were assigned to the stretching and bending vibrations of phosphate tetrahedra, water molecules and hydroxyl ions. Approximate O-H⋯O hydrogen bond lengths were inferred from the Raman and infrared spectra. No Raman and infrared bands attributable to the stretching and bending vibrations of (PO3OH)2- units were observed.

  5. Raman spectroscopic identification of normal and malignant hepatocytes

    Institute of Scientific and Technical Information of China (English)

    Jianyu Guo; Bing Du; Min Qian; Weiying Cai; Zugeng Wang; Zhenrong Sun

    2009-01-01

    Raman spectroscopy has strong potential for providing non-invasion diagnosis of cancers. In this paper, micro-Raman spectroscopy is used to diagnose one most common liver cancer, hepatocellular carcinoma (HCC). The statistical analyzes, including i-test, principal component analysis (PCA), and linear discrim inant analysis (LDA), are performed on the Raman spectra of malignant and normal hepatocytes. The t-test-LDA results show that the 786- and 1004-cm-1 bands of the malignant and normal hepatocytes are significantly different, and PCA-LDA results show an overall accuracy of 100% for the Raman spectro scopic identification of normal and malignant hepatocytes in our experiment.

  6. Phonon-Assisted Anti-Stokes Lasing in ZnTe Nanoribbons.

    Science.gov (United States)

    Zhang, Qing; Liu, Xinfeng; Utama, M Iqbal Bakti; Xing, Guichuan; Sum, Tze Chien; Xiong, Qihua

    2016-01-13

    Phonon-assisted anti-Stokes emission and its stimulated emission in polar semiconductor ZnTe are demonstrated via the annihilation of phonons as a result of strong exciton-phonon coupling. The findings are not only important for developing high-power radiation-balanced lasers, but are also promising for manufacturing ultraefficient solid-state laser coolers. PMID:26573758

  7. A Raman spectroscopic approach for the cultivation-free identification of microbes

    Science.gov (United States)

    Rösch, Petra; Stöckel, Stephan; Meisel, Susann; Münchberg, Ute; Kloß, Sandra; Kusic, Dragana; Schumacher, Wilm; Popp, Jürgen

    2011-12-01

    In the last years the identification of microorganisms by means of different IR and Raman spectroscopic techniques has become quite popular. Most of the studies however apply the various vibrational spectroscopic methods to bulk samples which require at least a short cultivation time of several hours. Nevertheless, bulk identification methods achieve high classification rates which enable even the discrimination between closely related strains or the distinction between resistance capabilities. However, applying micro-Raman spectroscopy with visible excitation wavelengths enables for the detection of single microorganisms. Especially for time critical process like the fast diagnosis of severe diseases or the identification of bacterial contamination on food samples or pharmaceuticals, a cultivation-free identification of bacteria is required. In doing so, we established different isolation techniques in combination with Raman spectroscopic identification. Isolating bacteria from different matrixes always has an impact on the Raman spectroscopic identification capability. Therefore, these isolation techniques have to be specially designed to fulfill the spectroscopic requirements. In total the method should enable the identification of pathogens within the first 3 hours.

  8. The pH dependent Raman spectroscopic study of caffeine

    Science.gov (United States)

    Kang, Jian; Gu, Huaimin; Zhong, Liang; Hu, Yongjun; Liu, Fang

    2011-02-01

    First of all the surface enhanced Raman spectroscopy (SERS) and normal Raman spectra of caffeine aqueous solution were obtained at different pH values. In order to obtain the detailed vibrational assignments of the Raman spectroscopy, the geometry of caffeine molecule was optimized by density functional theory (DFT) calculation. By comparing the SERS of caffeine with its normal spectra at different pH values; it is concluded that pH value can dramatically affect the SERS of caffeine, but barely affect the normal Raman spectrum of caffeine aqueous solution. It can essentially affect the reorientation of caffeine molecule to the Ag colloid surface, but cannot impact the vibration of functional groups and chemical bonds in caffeine molecule.

  9. Raman Spectroscopic Methods for Classification of Normal and Malignant Hypopharyngeal Tissues: An Exploratory Study

    Directory of Open Access Journals (Sweden)

    Parul Pujary

    2011-01-01

    Full Text Available Laryngeal cancer is more common in males. The present study is aimed at exploration of potential of conventional Raman spectroscopy in classifying normal from a malignant laryngopharyngeal tissue. We have recorded Raman spectra of twenty tissues (aryepiglottic fold using an in-house built Raman setup. The spectral features of mean malignant spectrum suggests abundance proteins whereas spectral features of mean normal spectrum indicate redundancy of lipids. PCA was employed as discriminating algorithm. Both, unsupervised and supervised modes of analysis as well as match/mismatch “limit test” methodology yielded clear classification among tissue types. The findings of this study demonstrate the efficacy of conventional Raman spectroscopy in classification of normal and malignant laryngopharyngeal tissues. A rigorous evaluation of the models with development of suitable fibreoptic probe may enable real-time Raman spectroscopic diagnosis of laryngopharyngeal cancers in future.

  10. Raman spectroscopic studies of lithium manganates with spinel structure

    CERN Document Server

    Julien, C M

    2003-01-01

    Raman scattering spectra of a set of lithium manganospinels Li sub 1 sub - sub x sub + sub z Mn sub 2 sub - sub z O sub 4 with 0 sup<= x sup<= 1 and 0 sup<= z sup<= 0.33 are reported and analysed. Structural changes have been investigated following the evolution of Raman spectra with the concentration of lithium cations. The local structure was characterized as a function of the mean oxidation state of manganese cations. The trigonal distortion of MnO sub 6 octahedra is evidenced by insertion of lithium ions into the [B sub 2]O sub 4 spinel framework. A comparison with tetragonal Mn sub 3 O sub 4 and Fe sub 3 O sub 4 spinels shows the influence of the Jahn-Teller effect on the Raman features for this class of materials.

  11. Raman spectroscopic analysis of isomers of biliverdin dimethyl ester.

    Science.gov (United States)

    Matysik, J; Hildebrandt, P; Smit, K; Mark, F; Gärtner, W; Braslavsky, S E; Schaffner, K; Schrader, B

    1997-06-01

    The constitutional isomers of biliverdin dimethyl ester, IX alpha and XIII alpha, were studied by resonance Raman spectroscopy. The far-reaching spectral similarities suggest that despite the different substitution patterns, the compositions of the normal modes are closely related. This conclusion does not hold only for the parent state (ZZZ, sss configuration) but also for the configurational isomers which were obtained upon double-bond photoisomerization. Based on a comparison of the resonance Raman spectra, a EZZ configuration is proposed for one of the two photoisomers of biliverdin dimethyl ester IX alpha, while a ZZE, ssa configuration has been assigned previously to the second isomer. PMID:9226559

  12. Method and system to measure temperature of gases using coherent anti-stokes doppler spectroscopy

    Science.gov (United States)

    Rhodes, Mark

    2013-12-17

    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.

  13. Observation of anti-stokes fluorescence cooling in thulium-doped glass

    Science.gov (United States)

    Hoyt; Sheik-Bahae; Epstein; Edwards; Anderson

    2000-10-23

    We report the first observation of anti-Stokes fluorescence cooling in a thulium-doped solid with pump excitation at 1.82 &mgr;mPbF2) sample cooled to -1.2 degrees C from room temperature for a single pass of the pump beam. This corresponds to an absorbed pump power of approximately 40 mW and a peak temperature change per absorbed power of approximately -30 degrees C/W from room temperature. PMID:11030960

  14. Local temperature variation measurement by anti-Stokes luminescence in attenuated total reflection geometry.

    Science.gov (United States)

    Yamamoto, Ken; Togawa, Ryotaro; Fujimura, Ryushi; Kajikawa, Kotaro

    2016-08-22

    Strong temperature dependence of anti-Stokes luminescence intensity from Rhodamine 101 is used to probe local temperature variation at a surface region in the attenuated total reflection geometry (ATR), when heating with laser light. In this method, the measured region can be limited by observing evanescent luminescence. The near-field depth (penetration depth) was changed by the observation angle θout of the evanescent luminescence and the spatial temperature variation was observed. PMID:27557182

  15. Raman spectroscopic study of ancient South African domestic clay pottery.

    Science.gov (United States)

    Legodi, M A; de Waal, D

    2007-01-01

    The technique of Raman spectroscopy was used to examine the composition of ancient African domestic clay pottery of South African origin. One sample from each of four archaeological sites including Rooiwal, Lydenburg, Makahane and Graskop was studied. Normal dispersive Raman spectroscopy was found to be the most effective analytical technique in this study. XRF, XRD and FT-IR spectroscopy were used as complementary techniques. All representative samples contained common features, which were characterised by kaolin (Al2Si2O5(OH)5), illite (KAl4(Si7AlO20)(OH)4), feldspar (K- and NaAlSi3O8), quartz (alpha-SiO2), hematite (alpha-Fe2O3), montmorillonite (Mg3(Si,Al)4(OH)2 x 4.5 5H(2)O[Mg]0.35), and calcium silicate (CaSiO3). Gypsum (CaSO4 x 2H2O) and calcium carbonates (most likely calcite, CaCO3) were detected by Raman spectroscopy in Lydenburg, Makahane and Graskop shards. Amorphous carbon (with accompanying phosphates) was observed in the Raman spectra of Lydenburg, Rooiwal and Makahane shards, while rutile (TiO(2)) appeared only in Makahane shard. The Raman spectra of Lydenburg and Rooiwal shards further showed the presence of anhydrite (CaSO4). The results showed that South African potters used a mixture of clays as raw materials. The firing temperature for most samples did not exceed 800 degrees C, which suggests the use of open fire. The reddish brown and grayish black colours were likely due to hematite and amorphous carbon, respectively. PMID:16839805

  16. Raman Spectroscopic Studies of Carbon Nanotube Composite Fibres

    OpenAIRE

    Deng, Libo

    2011-01-01

    The project has been concerned with structure/property relationships in a series of different carbon nanotube (CNT) composite fibres. Raman spectroscopy has been proved to be a powerful technique to characterise the CNT-containing fibres. Electrospinning has been used to prepare poly(vinyl alcohol) (PVA) nanofibres containing single-wall carbon nanotubes (SWNTs). The effect of the processing conditions including the polymer concentration, electric voltage, tip-to-collector distance, nanotube ...

  17. Raman spectroscopic differentiation of planktonic bacteria and biofilms.

    Science.gov (United States)

    Kusić, Dragana; Kampe, Bernd; Ramoji, Anuradha; Neugebauer, Ute; Rösch, Petra; Popp, Jürgen

    2015-09-01

    Both biofilm formations as well as planktonic cells of water bacteria such as diverse species of the Legionella genus as well as Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli were examined in detail by Raman microspectroscopy. Production of various molecules involved in biofilm formation of tested species in nutrient-deficient media such as tap water was observed and was particularly evident in the biofilms formed by six Legionella species. Biofilms of selected species of the Legionella genus differ significantly from the planktonic cells of the same organisms in their lipid amount. Also, all Legionella species have formed biofilms that differ significantly from the biofilms of the other tested genera in the amount of lipids they produced. We believe that the significant increase in the synthesis of this molecular species may be associated with the ability of Legionella species to form biofilms. In addition, a combination of Raman microspectroscopy with chemometric approaches can distinguish between both planktonic form and biofilms of diverse bacteria and could be used to identify samples which were unknown to the identification model. Our results provide valuable data for the development of fast and reliable analytic methods based on Raman microspectroscopy, which can be applied to the analysis of tap water-adapted microorganisms without any cultivation step.

  18. HPLC assisted Raman spectroscopic studies on bladder cancer

    Science.gov (United States)

    Zha, W. L.; Cheng, Y.; Yu, W.; Zhang, X. B.; Shen, A. G.; Hu, J. M.

    2015-04-01

    We applied confocal Raman spectroscopy to investigate 12 normal bladder tissues and 30 tumor tissues, and then depicted the spectral differences between the normal and the tumor tissues and the potential canceration mechanism with the aid of the high-performance liquid chromatographic (HPLC) technique. Normal tissues were demonstrated to contain higher tryptophan, cholesterol and lipid content, while bladder tumor tissues were rich in nucleic acids, collagen and carotenoids. In particular, β-carotene, one of the major types of carotenoids, was found through HPLC analysis of the extract of bladder tissues. The statistical software SPSS was applied to classify the spectra of the two types of tissues according to their differences. The sensitivity and specificity of 96.7 and 66.7% were obtained, respectively. In addition, different layers of the bladder wall including mucosa (lumps), muscle and adipose bladder tissue were analyzed by Raman mapping technique in response to previous Raman studies of bladder tissues. All of these will play an important role as a directive tool for the future diagnosis of bladder cancer in vivo.

  19. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga).

    Science.gov (United States)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  20. Raman spectroscopic study on the excystation process in a single unicellular organism amoeba (Acanthamoeba polyphaga)

    Science.gov (United States)

    Lin, Yu-Chung; Perevedentseva, Elena; Cheng, Chia-Liang

    2015-05-01

    An in vivo Raman spectroscopic study of amoeba (Acanthamoeba polyphaga) is presented. The changes of the spectra during the amoeba cyst activation and excystation are analyzed. The spectra show the changes of the relative intensities of bands corresponding to protein, lipid, and carotenoid components during cyst activation. The presence of carotenoids in the amoeba is observed via characteristic Raman bands. These signals in the Raman spectra are intense in cysts but decrease in intensity with cyst activation and exhibit a correlation with the life cycle of amoeba. This work demonstrates the feasibility of using Raman spectroscopy for the detection of single amoeba microorganisms in vivo and for the analysis of the amoeba life activity. The information obtained may have implications for the estimation of epidemiological situations and for the diagnostics and prognosis of the development of amoebic inflammations.

  1. Raman spectroscopic approach to monitor the in vitro cyclization of creatine → creatinine

    Science.gov (United States)

    Gangopadhyay, Debraj; Sharma, Poornima; Singh, Sachin Kumar; Singh, Pushkar; Tarcea, Nicolae; Deckert, Volker; Popp, Jürgen; Singh, Ranjan K.

    2015-01-01

    The creatine → creatinine cyclization, an important metabolic phenomenon has been initiated in vitro at acidic pH and studied through Raman spectroscopic and DFT approach. The equilibrium composition of neutral, zwitterionic and protonated microspecies of creatine has been monitored with time as the reaction proceeds. Time series Raman spectra show clear signature of creatinine formation at pH 3 after ∼240 min at room temperature and reaction is faster at higher temperature. The spectra at pH 1 and pH 5 do not show such signature up to 270 min implying faster reaction rate at pH 3.

  2. Coherent anti-Stokes Raman Scattering (CARS) Microscopy Visualizes Pharmaceutical Tablets During Dissolution

    NARCIS (Netherlands)

    Fussell, A.L.; Kleinebudde, P.; Herek, J.L.; Strachan, C.J.; Offerhaus, H.L.

    2014-01-01

    Traditional pharmaceutical dissolution tests determine the amount of drug dissolved over time by measuring drug content in the dissolution medium. This method provides little direct information about what is happening on the surface of the dissolving tablet. As the tablet surface composition and str

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

    NARCIS (Netherlands)

    Fussell, Andrew; Garbacik, Erik; Offerhaus, Herman; Kleinebudde, Peter; Strachan, Clare

    2013-01-01

    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

  4. Coherent anti-Stokes Raman spectroscopy in the presence of strong resonant signal from background molecules

    CERN Document Server

    Bitter, Martin

    2012-01-01

    Optical spectroscopy with broadband femtosecond laser pulses often involves simultaneous excitation of multiple molecular species with close resonance frequencies. Interpreting the collective optical response from molecular mixtures typically requires Fourier analysis of the detected time-resolved signal. We propose an alternative method of separating coherent optical responses from two molecular species with neighboring excitation resonances (here, vibrational modes of oxygen and carbon dioxide). We utilize ro-vibrational coupling as a mechanism of suppressing the strong vibrational response from the dominating molecular species (O$_{2}$). Coherent ro-vibrational dynamics lead to long "silence windows" of zero signal from oxygen molecules. In these silence windows, the detected signal stems solely from the minority species (CO$_{2}$) enabling background-free detection and characterization of the O$_2$/CO$_2$ mixing ratio. In comparison to a Fourier analysis, our technique does not require femtosecond time re...

  5. Amorphous silicon deposition diagnostics using coherent anti-Stokes Raman spectroscopy

    Science.gov (United States)

    Shing, Y. H.; Perry, J. W.; Coulter, D. R.; Radhakrishnan, G.

    1987-01-01

    This paper reports on an in situ silicon deposition process diagnostics, using CARS performed at state-of-the-art a-Si:H film deposition conditions in a reactor designed for a-Si:H solar cell fabrication. The diagnostics procedure measures the silane depletion in an RF plasma as a function of the silane flow rate (where the relationship is linear between 50-percent depletion, at a flow rate of 5.6 sccm, and about 8-percent depletion, at 80 sccm) and the RF power (where the silane depletion is linearly dependent on the RF power in the region of 4 to 12 W). The linear RF power dependence of the silane depletion is considered to be consistent with the mechanism of silane decomposition primarily by electron impact dissociations, while the flow rate dependence is interpreted in terms of the residence time of the SiH4 molecules in the glow discharge region, where an increase of the residence time at a low flow rate results in a high depletion ratio.

  6. How specific Raman spectroscopic models are: a comparative study between different cancers

    Science.gov (United States)

    Singh, S. P.; Kumar, K. Kalyan; Chowdary, M. V. P.; Maheedhar, K.; Krishna, C. Murali

    2010-02-01

    Optical spectroscopic methods are being contemplated as adjunct/ alternative to existing 'Gold standard' of cancer diagnosis, histopathological examination. Several groups are actively pursuing diagnostic applications of Ramanspectroscopy in cancers. We have developed Raman spectroscopic models for diagnosis of breast, oral, stomach, colon and larynx cancers. So far, specificity and applicability of spectral- models has been limited to particular tissue origin. In this study we have evaluated explicitly of spectroscopic-models by analyzing spectra from already developed spectralmodels representing normal and malignant tissues of breast (46), cervix (52), colon (25), larynx (53), and oral (47). Spectral data was analyzed by Principal Component Analysis (PCA) using scores of factor, Mahalanobis distance and Spectral residuals as discriminating parameters. Multiparametric limit test approach was also explored. The preliminary unsupervised PCA of pooled data indicates that normal tissue types were always exclusive from their malignant counterparts. But when we consider tissue of different origin, large overlap among clusters was found. Supervised analysis by Mahalanobis distance and spectral residuals gave similar results. The 'limit test' approach where classification is based on match / mis-match of the given spectrum against all the available spectra has revealed that spectral models are very exclusive and specific. For example breast normal spectral model show matches only with breast normal spectra and mismatch to rest of the spectra. Same pattern was seen for most of spectral models. Therefore, results of the study indicate the exclusiveness and efficacy of Raman spectroscopic-models. Prospectively, these findings might open new application of Raman spectroscopic models in identifying a tumor as primary or metastatic.

  7. Laser Raman spectroscopic analysis of polymorphic forms in microliter fluid volumes.

    Science.gov (United States)

    Anquetil, Patrick A; Brenan, Colin J H; Marcolli, Claudia; Hunter, Ian W

    2003-01-01

    Knowledge and control of the polymorphic phase of chemical compounds are important aspects of drug development in the pharmaceutical industry. We report herein in situ and real-time Raman spectroscopic polymorphic analysis of optically trapped microcrystals in a microliter volume format. The system studied in particular was the recrystallization of carbamazepine (CBZ) in methanol. Raman spectrometry enabled noninvasive measurement of the amount of dissolved CBZ in a sample as well as polymorphic characterization, whereas exclusive recrystallization of either CBZ form I or CBZ form III from saturated solutions was achieved by specific selection of sample cell cooling profiles. Additionally, using a microcell versus a macroscopic volume gives the advantage of reaching equilibrium much faster while using little compound quantity. We demonstrate that laser Raman spectral polymorphic analysis in a microliter cell is a potentially viable screening platform for polymorphic analysis and could lead to a new high throughput method for polymorph screening.

  8. Biodegradable starch-based films containing saturated fatty acids: thermal, infrared and raman spectroscopic characterization

    Directory of Open Access Journals (Sweden)

    Marcelo M. Nobrega

    2012-01-01

    Full Text Available Biodegradable films of thermoplastic starch and poly (butylene adipate co-terephthalate (PBAT containing fatty acids were characterized thermally and with infrared and Raman spectroscopies. The symmetrical character of the benzene ring in PBAT provided a means to illustrate the difference between these spectroscopic techniques, because a band appeared in the Raman spectrum but not in the infrared. The thermal analysis showed three degradation stages related to fatty acids, starch and PBAT. The incorporation of saturated fatty acids with different molecular mass (caproic, lauric and stearic did not change the nature of the chemical bonds among the components in the blends of starch, PBAT and glycerol, according to the thermal analysis, infrared and Raman spectroscopies.

  9. Scytonin, a novel cyanobacterial photoprotective pigment: calculations of Raman spectroscopic biosignatures.

    Science.gov (United States)

    Varnali, Tereza; Edwards, Howell G M

    2014-03-01

    The Raman spectrum of scytonin, a novel derivative of the parent scytonemin, is predicted from DFT calculations of the most stable, lowest energy, conformational structure. The diagnostic importance of this study relates to the spectral ability to discriminate between scytonemin and its derivatives alone or in admixture with geological matrices from identified characteristic Raman spectral signatures. The successful interpretation of biosignatures from a wide range of cyanobacterial extremophilic colonization in terrestrial and extraterrestrial scenarios is a fundamental requirement of the evaluation of robotic spectroscopic instrumentation in search for life missions. Scytonemin is produced exclusively by cyanobacterial colonies in environmentally stressed habitats and is widely recognized as a key target biomarker molecule in this enterprise. Here, the detailed theoretical analysis of the structure of scytonin enables a protocol to be established for the recognition of characteristic bands in its Raman spectrum and to accomplish the successful differentiation between scytonin and scytonemin as well as other scytonemin derivatives such as the dimethoxy and tetramethoxy compounds that have been isolated from cyanobacterial colonies but which have not yet been characterized spectroscopically. The results of this study will facilitate an extension of the database capability for miniaturized Raman spectrometers which will be carried on board search for life robotic missions to Mars, Europa, and Titan. PMID:24567163

  10. Photon-phonon anti-stokes upconversion of a photonically, electronically, and thermally isolated opal

    Science.gov (United States)

    Stem, Michelle R.

    2016-05-01

    The purpose of the present research was to investigate an intense violet shift displayed by a non-toxic, natural silicate material with a highly ordered nanostructure. The material displayed an unexpected, nonlinear 2:3 photon-phonon anti-Stokes upconversion while photonically, electronically, and thermally isolated. Conducted aphotonically and at ambient temperatures, the specimen upconverted a low-power, 650 nm constant wave red laser to an internally highly dispersed 433 nm violet wavelength. The strong dispersion was largely due to nearly total internal reflection of the laser. The upconversion had an efficiency of about 78 %, based on specimen volume, with no detectable thermal variance. The 2:3 anti-Stokes upconversion displayed by this material is likely the result of a previously unknown photon-phonon evanescence response that amplified the energy of a portion of the incident laser photons. Thus, a portion of the incident laser photons were upconverted, and the material converted another portion into an amplified energy that caused the upconversion. Internal micro-lasing appeared to be a means of photon-phonon evanescent energy redistribution, enabling dispersed photonic upconversion. Additional analyses also found an unexpectedly rhythmic photonic structure in spectrophotometric scans, polariscopic color changing, and previously undocumented ultraviolet responses.

  11. Raman spectroscopic study of keratin 8 knockdown oral squamous cell carcinoma derived cells

    Science.gov (United States)

    Singh, S. P.; Alam, Hunain; Dmello, Crismita; Vaidya, Milind M.; Krishna, C. Murali

    2012-03-01

    Keratins are one of most widely used markers for oral cancers. Keratin 8 and 18 are expressed in simple epithelia and perform both mechanical and regulatory functions. Their expression are not seen in normal oral tissues but are often expressed in oral squamous cell carcinoma. Aberrant expression of keratins 8 and 18 is most common change in human oral cancer. Optical-spectroscopic methods are sensitive to biochemical changes and being projected as novel diagnostic tools for cancer diagnosis. Aim of this study was to evaluate potentials of Raman spectroscopy in detecting minor changes associated with differential level of keratin expression in tongue-cancer-derived AW13516 cells. Knockdown clones for K8 were generated and synchronized by growing under serum-free conditions. Cell pellets of three independent experiments in duplicate were used for recording Raman spectra with fiberoptic-probe coupled HE-785 Raman-instrument. A total of 123 and 96 spectra from knockdown clones and vector controls respectively in 1200-1800 cm-1 region were successfully utilized for classification using LDA. Two separate clusters with classification-efficiency of ~95% were obtained. Leave-one-out cross-validation yielded ~63% efficiency. Findings of the study demonstrate the potentials of Raman spectroscopy in detecting even subtle changes such as variations in keratin expression levels. Future studies towards identifying Raman signals from keratin in oral cells can help in precise cancer diagnosis.

  12. Raman spectroscopic detection of biomolecular markers from Antarctic materials: evaluation for putative Martian habitats

    Science.gov (United States)

    Edwards, Howell G. M.; Newton, Emma M.; Dickensheets, David L.; Wynn-Williams, David D.

    2003-08-01

    The vital UV-protective and photosynthetic pigments of cyanobacteria and lichens (microbial symbioses) that dominate primary production in Antarctic desert ecosystems auto-fluoresce at short-wavelengths. A long wavelength (1064 nm) near infra-red laser has been used for non-intrusive Raman spectroscopic analysis of their ecologically significant compounds. There is now much interest in the construction of portable Raman systems for the analysis of cyanobacterial and lichen communities in the field; to this extent, Raman spectra obtained with laboratory-based systems operating at wavelengths of 852 and 1064 nm have been evaluated for potential fieldwork applications of miniaturised units. Selected test specimens of the cyanobacterial Nostoc commune, epilithic lichens Acarospora chlorophana, Xanthoria elegans and Caloplaca saxicola and the endolithic Chroococcidiopsis from Antarctic sites have been examined in the present study. Although some organisms gave useable Raman spectra with short-wavelength lasers, 1064 nm was the only excitation that was consistently excellent for all organisms. We conclude that a 1064 nm Raman spectrometer, miniaturised using an InGaAs detector, is the optimal instrument for in situ studies of pigmented communities at the limits of life on Earth. This has practical potential for the quest for biomolecules residual from any former surface or subsurface life on Mars.

  13. Raman spectroscopic identification of scytonemin and its derivatives as key biomarkers in stressed environments.

    Science.gov (United States)

    Varnali, Tereza; Edwards, Howell G M

    2014-12-13

    Raman spectroscopy has been identified as an important first-pass analytical technique for deployment on planetary surfaces as part of a suite of instrumentation in projected remote space exploration missions to detect extant or extinct extraterrestrial life signatures. Aside from the demonstrable advantages of a non-destructive sampling procedure and an ability to record simultaneously the molecular signatures of biological, geobiological and geological components in admixture in the geological record, the interrogation and subsequent interpretation of spectroscopic data from these experiments will be critically dependent upon the recognition of key biomolecular markers indicative of life existing or having once existed in extreme habitats. A comparison made with the characteristic Raman spectral wavenumbers obtained from standards is not acceptable because of shifts that can occur in the presence of other biomolecules and their host mineral matrices. In this paper, we identify the major sources of difficulty experienced in the interpretation of spectroscopic data centring on a key family of biomarker molecules, namely scytonemin and its derivatives; the parent scytonemin has been characterized spectroscopically in cyanobacterial colonies inhabiting some of the most extreme terrestrial environments and, with the support of theoretical calculations, spectra have been predicted for the characterization of several of its derivatives which could occur in novel extraterrestrial environments. This work will form the foundation for the identification of novel biomarkers and for their Raman spectroscopic discrimination, an essential step in the interpretation of potentially complex and hitherto unknown biological radiation protectants based on the scytoneman and scytonin molecular skeletons which may exist in niche geological scenarios in the surface and subsurface of planets and their satellites in our Solar System. PMID:25368346

  14. Dynamic behaviour of the 'Raman spectroscopic signature of life' in a starving budding yeast cell

    International Nuclear Information System (INIS)

    Complete text of publication follows. In vivo molecular-level information is essentially important for understanding the structure, dynamics and functions of living cells. We use Raman microspectroscopy to single living budding yeast cells under a starving condition and study the dynamic behaviour of the 'Raman spectroscopic signature of life' (Y. Naito et al., J. Raman. Spectrosc., 36 (2005) 837-839. and Y-S. Huang et al., Biochemistry, 44 (2005) 10009-10019.) in relation to the formation and disappearance of a 'dancing body' in a vacuole. A focus is placed on the cell death process and the recovery from it. Our previous studies have shown that, under a starving condition, a dancing body appears suddenly in a vacuole and that the 'Raman spectroscopic signature of life' disappears concomitantly indicating the loss of the mitochondrial metabolic activity. This event is followed by gradual deterioration of the cell structure leading to death. This cell death process was visualized at the molecular level by time-resolved Raman imaging. In the present study, we show strong correlations not only between the appearance of a dancing body and the loss of the mitochondrial activity but also between the disappearance of the dancing body and the recovery of the activity. Time- and space-resolved Raman spectra of a single living budding yeast cell were recorded on a confocal Raman microspectrometer with 632.8 nm line of a He-Ne laser for excitation. The laser power at the sample was about 5 mW. The lateral and depth resolutions were about 300 nm with a 100 x oil immersion objective lens (N.A.=1.3) and about 2 μm with a 100 μm pinhole for a confocal detection. Raman spectra were recorded in the wavenumber range 300 - 1800 cm-1 with a spectral resolution of 3 cm-1. The exposure time was 150 sec. Saccharomyces cerevisiae/ Saccharomyces Bayanus hybrid, strain AJL3062 from, was grown at 30 deg C under a stationary cultivation condition in wort medium. The cells dispersed in 1 ml

  15. Raman spectroscopic investigation of polycrystalline structures of CVD-grown graphene by isotope labeling

    Science.gov (United States)

    Wang, Shengnan; Suzuki, Satoru; Hibino, Hiroki

    2014-10-01

    Topological defects, such as point defects, dislocations and grain boundaries, have a dramatic influence on the chemical and physical properties of large-scale graphene grown by chemical vapor deposition (CVD) method. Here we demonstrate the Raman visualization of polycrystalline structures in an isotopically modified CVD graphene. By means of the reversible reaction of methane on a copper catalyst, the etching of 12C-lattice and surface deposition of 13C-atoms occur in CVD graphene by sequentially introducing hydrogen and isotopic methane after standard growth of graphene with full monolayer coverage. Spatial Raman spectroscopic mapping on labeled graphene reveals pronounced network-like 13C-rich regions, which are further identified to exist along the grain boundaries of graphene by low-energy electron microscopy. The structural defects inside the graphene grains are also targeted in the isotope labeling process. Our work opens a new way to investigate multiple grain structures in CVD graphene with a simple spectroscopic technique.Topological defects, such as point defects, dislocations and grain boundaries, have a dramatic influence on the chemical and physical properties of large-scale graphene grown by chemical vapor deposition (CVD) method. Here we demonstrate the Raman visualization of polycrystalline structures in an isotopically modified CVD graphene. By means of the reversible reaction of methane on a copper catalyst, the etching of 12C-lattice and surface deposition of 13C-atoms occur in CVD graphene by sequentially introducing hydrogen and isotopic methane after standard growth of graphene with full monolayer coverage. Spatial Raman spectroscopic mapping on labeled graphene reveals pronounced network-like 13C-rich regions, which are further identified to exist along the grain boundaries of graphene by low-energy electron microscopy. The structural defects inside the graphene grains are also targeted in the isotope labeling process. Our work opens a new

  16. Studies on Nephrite and Jadeite Jades by Fourier Transform Infrared (ftir) and Raman Spectroscopic Techniques

    Science.gov (United States)

    Tan, T. L.; Ng, L. L.; Lim, L. C.

    2013-10-01

    The mineralogical properties of black nephrite jade from Western Australia are studied by Fourier transform infrared (FTIR) spectroscopy using both transmission and specular reflectance techniques in the 4000-400 cm-1 wavenumber region. The infrared absorption peaks in the 3700-3600 cm-1 region which are due to the O-H stretching mode provides a quantitative analysis of the Fe/(Fe+Mg) ratio in the mineral composition of jade samples. The Fe/(Fe+Mg) percentage in black nephrite is found to be higher than that in green nephrite, but comparable to that of actinolite (iron-rich nephrite). This implies that the mineralogy of black nephrite is closer to actinolite than tremolite. The jade is also characterized using Raman spectroscopy in the 1200-200 cm-1 region. Results from FTIR and Raman spectroscopic data of black nephrite jade are compared with those of green nephrite jade from New Zealand and jadeite jade from Myanmar. Black nephrite appears to have a slightly different chemical composition from green nephrite. Spectra from FTIR and Raman spectroscopic techniques were found to be useful in differentiating black nephrite, green nephrite, and green jadeite jades. Furthermore, data on refractive index, specific gravity, and hardness of black nephrite jade are measured and compared with those of green nephrite and of jadeite jade.

  17. Low temperature FTIR, Raman, NMR spectroscopic and theoretical study of hydroxyethylammonium picrate

    Science.gov (United States)

    Sudharsana, N.; Sharma, A.; Kuş, N.; Fausto, R.; Luísa Ramos, M.; Krishnakumar, V.; Pal, R.; Guru Row, T. N.; Nagalakshmi, R.

    2016-01-01

    A combined experimental (infrared, Raman and NMR) and theoretical quantum chemical study is performed on the charge-transfer complex hydroxyethylammonium picrate (HEAP). The infrared (IR) spectra for HEAP were recorded at various temperatures, ranging from 16 K to 299 K, and the Raman spectrum was recorded at room temperature. A comparison of the experimental IR and Raman spectra with the corresponding calculated spectra was done, in order to facilitate interpretation of the experimental data. Formation of the HEAP complex is evidenced by the presence of the most prominent characteristic bands of the constituting groups of the charge-transfer complex [e.g., NH3+, CO- and NO2]. Vibrational spectroscopic analysis, together with natural bond orbital (NBO) and theoretical charge density analysis in the crystalline phase, was used to shed light on relevant structural details of HEAP resulting from deprotonation of picric acid followed by formation of a hydrogen bond of the N-H⋯OC type between the hydroxyethylammonium cation and the picrate. 13C and 1H NMR spectroscopic analysis are also presented for the DMSO-d6 solution of the compound revealing that in that medium the HEAP crystal dissolves forming the free picrate and hydroxyethylammonium ions. Finally, the electron excitation analysis of HEAP was performed in an attempt to determine the nature of the most important excited states responsible for the NLO properties exhibited by the compound.

  18. Reduced and oxidised scytonemin: theoretical protocol for Raman spectroscopic identification of potential key biomolecules for astrobiology.

    Science.gov (United States)

    Varnali, Tereza; Edwards, Howell G M

    2014-01-01

    Scytonemin is an important UV-radiation protective biomolecule synthesised by extremophilic cyanobacteria in stressed terrestrial environments. Scytonemin and its reduced form have been both isolated experimentally and the Raman spectrum for scytonemin has been assigned and characterised experimentally both in extracts and in living extremophilic cyanobacterial colonies. Scytonemin is recognised as a key biomarker molecule for terrestrial organisms in stressed environments. We propose a new, theoretically plausible structure for oxidised scytonemin which has not been mentioned in the literature hitherto. DFT calculations for scytonemin, reduced scytonemin and the new structure modelled and proposed for oxidised scytonemin are reported along with their Raman spectroscopic data and λmax UV-absorption data obtained theoretically. Comparison of the vibrational spectroscopic assignments allows the three forms of scytonemin to be detected and identified and assist not only in the clarification of the major features in the experimentally observed Raman spectral data for the parent scytonemin but also support a protocol proposed for their analytical discrimination. The results of this study provide a basis for the search for molecules of this type in future astrobiological missions of exploration and the search for extinct and extant life terrestrially.

  19. Raman spectroscopic imaging as complementary tool for histopathologic assessment of brain tumors

    Science.gov (United States)

    Krafft, Christoph; Bergner, Norbert; Romeike, Bernd; Reichart, Rupert; Kalff, Rolf; Geiger, Kathrin; Kirsch, Matthias; Schackert, Gabriele; Popp, Jürgen

    2012-02-01

    Raman spectroscopy enables label-free assessment of brain tissues and tumors based on their biochemical composition. Combination of the Raman spectra with the lateral information allows grading of tumors, determining the primary tumor of brain metastases and delineating tumor margins - even during surgery after coupling with fiber optic probes. This contribution presents exemplary Raman spectra and images collected from low grade and high grade regions of astrocytic gliomas and brain metastases. A region of interest in dried tissue sections encompassed slightly increased cell density. Spectral unmixing by vertex component analysis (VCA) and N-FINDR resolved cell nuclei in score plots and revealed the spectral contributions of nucleic acids, cholesterol, cholesterol ester and proteins in endmember signatures. The results correlated with the histopathological analysis after staining the specimens by hematoxylin and eosin. For a region of interest in non-dried, buffer immersed tissue sections image processing was not affected by drying artifacts such as denaturation of biomolecules and crystallization of cholesterol. Consequently, the results correspond better to in vivo situations. Raman spectroscopic imaging of a brain metastases from renal cell carcinoma showed an endmember with spectral contributions of glycogen which can be considered as a marker for this primary tumor.

  20. Combined FT-Raman spectroscopic and mass spectrometric study of ancient Egyptian sarcophagal fragments.

    Science.gov (United States)

    Edwards, Howell G M; Stern, Ben; Villar, Susana E Jorge; David, A Rosalie

    2007-02-01

    The application of combined Raman spectroscopic and GC-MS analytical techniques for the characterisation of organic varnish residues from Egyptian Dynastic funerary sarcophagal and cartonnage fragments from the Graeco-Roman period, ca. 2200 BP, is described. The nondestructive use of Raman spectroscopy was initially employed to derive information about the specific location of organic material on the specimens, which were then targeted in specific areas using minimal sampling for GC-MS analysis. In the case of the sarcophagal fragment, a degraded yellow-brown surface treatment was identified as a Pistacia spp. resin; this provides additional evidence for the use of this resin, which has previously been identified in Canaanite transport amphorae, varnishes and "incense" bowls in an Egyptian Late Bronze Age archaeological context. The cartonnage fragment also contained an organic coating for which the Raman spectrum indicated a degradation that was too severe to facilitate identification, but the GC-MS data revealed that it was composed of a complex mixture of fatty acid residues. The combined use of GC-MS and Raman spectroscopy for the characterisation of organic materials in an archaeological context is advocated for minimisation of sampling and restriction to specifically identified targets for museum archival specimens. PMID:16896625

  1. Combined FT-Raman spectroscopic and mass spectrometric study of ancient Egyptian sarcophagal fragments.

    Science.gov (United States)

    Edwards, Howell G M; Stern, Ben; Villar, Susana E Jorge; David, A Rosalie

    2007-02-01

    The application of combined Raman spectroscopic and GC-MS analytical techniques for the characterisation of organic varnish residues from Egyptian Dynastic funerary sarcophagal and cartonnage fragments from the Graeco-Roman period, ca. 2200 BP, is described. The nondestructive use of Raman spectroscopy was initially employed to derive information about the specific location of organic material on the specimens, which were then targeted in specific areas using minimal sampling for GC-MS analysis. In the case of the sarcophagal fragment, a degraded yellow-brown surface treatment was identified as a Pistacia spp. resin; this provides additional evidence for the use of this resin, which has previously been identified in Canaanite transport amphorae, varnishes and "incense" bowls in an Egyptian Late Bronze Age archaeological context. The cartonnage fragment also contained an organic coating for which the Raman spectrum indicated a degradation that was too severe to facilitate identification, but the GC-MS data revealed that it was composed of a complex mixture of fatty acid residues. The combined use of GC-MS and Raman spectroscopy for the characterisation of organic materials in an archaeological context is advocated for minimisation of sampling and restriction to specifically identified targets for museum archival specimens.

  2. Raman and terahertz spectroscopical investigation of cocrystal formation process of piracetam and 3-hydroxybenzoic acid

    Science.gov (United States)

    Du, Yong; Zhang, Huili; Xue, Jiadan; Fang, Hongxia; Zhang, Qi; Xia, Yi; Li, Yafang; Hong, Zhi

    2015-03-01

    Cocrystallization can improve physical and chemical properties of active pharmaceutical ingredient, and this feature has great potential in pharmaceutical development. In this study, the cocrystal of piracetam and 3-hydroxybenzoic acid under grinding condition has been characterized by Raman and terahertz spectroscopical techniques. The major vibrational modes of individual starting components and cocrystal are obtained and assigned. Spectral results show that the vibrational modes of the cocrystal are different from those of the corresponding parent materials. The dynamic process of such pharmaceutical cocrystal formation has also been monitored directly with Raman and THz spectra. The formation rate is pretty fast in first several 20 min grinding time, and then it becomes slow. After ∼35 min, such process has been almost completed. These results offer us the unique means and benchmark for characterizing the cocrystal conformation from molecule-level and also provide us rich information about the reaction dynamic during cocrystal formation process in pharmaceutical fields.

  3. Raman spectroscopic sensing of carbonate intercalation in breast microcalcifications at stereotactic biopsy

    Science.gov (United States)

    Sathyavathi, R.; Saha, Anushree; Soares, Jaqueline S.; Spegazzini, Nicolas; McGee, Sasha; Rao Dasari, Ramachandra; Fitzmaurice, Maryann; Barman, Ishan

    2015-04-01

    Microcalcifications are an early mammographic sign of breast cancer and frequent target for stereotactic biopsy. Despite their indisputable value, microcalcifications, particularly of the type II variety that are comprised of calcium hydroxyapatite deposits, remain one of the least understood disease markers. Here we employed Raman spectroscopy to elucidate the relationship between pathogenicity of breast lesions in fresh biopsy cores and composition of type II microcalcifications. Using a chemometric model of chemical-morphological constituents, acquired Raman spectra were translated to characterize chemical makeup of the lesions. We find that increase in carbonate intercalation in the hydroxyapatite lattice can be reliably employed to differentiate benign from malignant lesions, with algorithms based only on carbonate and cytoplasmic protein content exhibiting excellent negative predictive value (93-98%). Our findings highlight the importance of calcium carbonate, an underrated constituent of microcalcifications, as a spectroscopic marker in breast pathology evaluation and pave the way for improved biopsy guidance.

  4. Fourier-transform Raman spectroscopic study of pigments in native American Indian rock art: Seminole Canyon

    Science.gov (United States)

    Edwards, H. G. M.; Drummond, L.; Russ, J.

    1998-10-01

    Samples of rock art (ca. 3000-4200 years BP) from the Lower Pecos region of Texas, near the confluences of the Pecos and Devils rivers with the Rio Grande, have been analysed using Raman microscopy. This rock art represents some of the finest pictographs known in North America. The red pigment is confirmed to be red ochre (iron (III) oxide and clay) whereas the black pigment is manganese (IV) oxide. White areas of the paintings are identified as calcium oxalate monohydrate (whewellite), whose presence could indicate the previous colonisation of the shelter walls by lichens. The black pigmented areas only contained Raman spectroscopic evidence for organic matter which was probably used as a binding agent.

  5. Raman spectroscopic study of “The Malatesta”: A Renaissance painting?

    Science.gov (United States)

    Edwards, Howell G. M.; Vandenabeele, Peter; Benoy, Timothy J.

    2015-02-01

    Raman spectroscopic analysis of the pigments on an Italian painting described as a "Full Length Portrait of a Gentleman", known also as the "Malatesta", and attributed to the Renaissance period has established that these are consistent with the historical research provenance undertaken earlier. Evidence is found for the early 19th Century addition of chrome yellow to highlighted yellow ochre areas in comparison with a similar painting executed in 1801 by Sir Thomas Lawrence of John Kemble in the role of Hamlet, Prince of Denmark. The Raman data are novel in that no analytical studies have previously been made on this painting and reinforces the procedure whereby scientific analyses are accompanied by parallel historical research.

  6. Raman Spectroscopy and Related Techniques in Biomedicine

    OpenAIRE

    Alistair Elfick; Andrew Downes

    2010-01-01

    In this review we describe label-free optical spectroscopy techniques which are able to non-invasively measure the (bio)chemistry in biological systems. Raman spectroscopy uses visible or near-infrared light to measure a spectrum of vibrational bonds in seconds. Coherent anti-Stokes Raman (CARS) microscopy and stimulated Raman loss (SRL) microscopy are orders of magnitude more efficient than Raman spectroscopy, and are able to acquire high quality chemically-specific images in seconds. We dis...

  7. Infrared and Raman spectroscopic studies of glasses with NASICON-type chemistry

    Indian Academy of Sciences (India)

    K J Rao; K C Sobha; Sundeep Kumar

    2001-10-01

    Structures of NASICON glasses of the general formula AB2(PO4)3, where A = Li, Na or K and B = Fe, Ga, Ti, V or Nb, have been investigated using vibrational (IR and Raman) spectroscopies. Phosphate species appear to establish an equilibrium via a disproportionation reaction involving a dynamical bond-switching mechanism where both charge and bonds are conserved. B ions in the system acquire different coordinations to oxygens. Alkali ions cause absorptions due to cage vibrations. All the observed spectroscopic features are consistent with speciation involving disproportionation reactions.

  8. Raman spectroscopic evidence of tissue restructuring in heat-induced tissue fusion.

    Science.gov (United States)

    Su, Lei; Cloyd, Kristy L; Arya, Shobhit; Hedegaard, Martin A B; Steele, Joseph A M; Elson, Daniel S; Stevens, Molly M; Hanna, George B

    2014-09-01

    Heat-induced tissue fusion via radio-frequency (RF) energy has gained wide acceptance clinically and here we present the first optical-Raman-spectroscopy study on tissue fusion samples in vitro. This study provides direct insights into tissue constituent and structural changes on the molecular level, exposing spectroscopic evidence for the loss of distinct collagen fibre rich tissue layers as well as the denaturing and restructuring of collagen crosslinks post RF fusion. These findings open the door for more advanced optical feedback-control methods and characterization during heat-induced tissue fusion, which will lead to new clinical applications of this promising technology.

  9. 13C Solid State Nuclear Magnetic Resonance and µ-Raman Spectroscopic Characterization of Sicilian Amber.

    Science.gov (United States)

    Barone, Germana; Capitani, Donatella; Mazzoleni, Paolo; Proietti, Noemi; Raneri, Simona; Longobardo, Ugo; Di Tullio, Valeria

    2016-08-01

    (13)C cross-polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) and µ-Raman spectroscopy were applied to characterize Sicilian amber samples. The main goal of this work was to supply a complete study of simetite, highlighting discriminating criteria useful to distinguish Sicilian amber from fossil resins from other regions and laying the foundations for building a spectroscopic database of Sicilian amber. With this aim, a private collection of unrefined simetite samples and fossil resins from the Baltic region and Dominican Republic was analyzed. Overall, the obtained spectra permitted simetite to be distinguished from the other resins. In addition, principal component analysis (PCA) was applied to the spectroscopic data, allowing the clustering of simetite samples with respect to the Baltic and Dominican samples and to group the simetite samples in two sets, depending on their maturity. Finally, the analysis of loadings allowed for a better understanding of the spectral features that mainly influenced the discriminating characteristics of the investigated ambers.

  10. High-efficiency broadband anti-Stokes emission from Yb3+-doped bulk crystals.

    Science.gov (United States)

    Zhu, Siqi; Wang, Chunhao; Li, Zhen; Jiang, Wei; Wang, Yichuan; Yin, Hao; Wu, Lidan; Chen, Zhenqiang; Zhang, Ge

    2016-05-15

    We investigate the broadband anti-Stokes emission (BASE) from Yb3+-doped crystals with a laser diode (LD) pumping at 940 nm. Our experiment reveals that Yb3+-doped crystals with random cracks are able to generate bright BASE at room temperature and atmospheric pressure. By examining the various characteristics of the crystals and the emitted light, we supply a theory for interpreting the underlying physics for this variety of BASE. In particular, we take into consideration the effects of energy migration, avalanche process, and charge-transfer luminescence. This represents the first time, to the best of our knowledge, that BASE was obtained from Yb3+-doped bulk crystals with a high optical-optical efficiency. PMID:27176947

  11. Single-Beam Coherent Raman Spectroscopy and Microscopy via Spectral Notch Shaping

    CERN Document Server

    Katz, Ori; Grinvald, Eran; Silberberg, Yaron

    2010-01-01

    Raman spectroscopy is one of the key techniques in the study of vibrational modes and molecular structures. In Coherent Anti-Stokes Raman Scattering (CARS) spectroscopy, a molecular vibrational spectrum is resolved via the third-order nonlinear interaction of pump, Stokes and probe photons, typically using a complex experimental setup with multiple beams and laser sources. Although CARS has become a widespread technique for label-free chemical imaging and detection of contaminants, its multi-source, multi-beam experimental implementation is challenging. In this work we present a simple and easily implementable scheme for performing single-beam CARS spectroscopy and microscopy using a single femtosecond pulse, shaped by a tunable narrowband notch filter. As a substitute for multiple sources, the single broadband pulse simultaneously provides the pump, Stokes and probe photons, exciting a broad band of vibrational levels. High spectroscopic resolution is obtained by utilizing a tunable spectral notch, shaped wi...

  12. Raman Spectroscopic Study Of The Dehydration Of Sulfates Using An Acoustic Levitator

    Science.gov (United States)

    Brotton, Stephen; Kaiser, R.

    2012-10-01

    The martian orbiters, landers, and rovers identified water-bearing sulfates on the martian surface. Furthermore, the Galileo mission suggests that hydrated salts such as magnesium sulfate are present on the surface of Europa and Ganymede. To understand the hydrologic history of Mars and some of Jupiter’s and Saturn’s moons, future missions need to identify in situ the hydration states of sulfates including magnesium sulfate (MgSO4 • nH2O n = 7, 6, . . ., 0), gypsum (CaSO4 • 2H2O), bassanite (CaSO4 • 0.5H2O) and anhydrite (CaSO4). Raman spectroscopy is ideally suited for this purpose, since the Raman spectrum for each different degree of hydration is unique. To obtain laboratory Raman spectra for comparison with the in situ measurements, we have developed a novel apparatus combining an acoustic levitator and a pressure-compatible process chamber. Particles with diameters between 10 µm and a few mm can be levitated at the pressure nodes of the ultrasonic standing wave. The chamber is interfaced to complimentary FTIR and Raman spectroscopic probes to characterize any chemical and physical modifications of the levitated particles. The particles can be heated to well-defined temperatures between 300 K and 1000 K using a carbon dioxide laser; the temperature of the particle will be probed via its black-body spectrum. The present apparatus enables (i) the production of high particle temperatures, (ii) precise measurement of the temperature, and (iii) accurate control of the environmental conditions (gas pressure and composition) within the chamber. Using this apparatus, we have studied the dehydration of sulfates including gypsum and epsomite (MgSO4 • 7H2O) in an anhydrous nitrogen atmosphere. We will present spectra showing the variation of the Raman spectra as gypsum, for example, is dehydrated to form anhydrite.

  13. Microthermometric and Raman spectroscopic detection limits of CO{sub 2} in fluid inclusions and the Raman spectroscopic characterization of CO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Rosso, K.M.; Bodnar, R.J. [Virginia Polytechnic Institute and State Univ., Blacksburg, VA (United States)

    1995-10-01

    In many geologic environments, dominantly aqueous solutions contain low concentrations of CO{sub 2}. At ambient temperature, the typical phase assemblage in fluid inclusions which trap these solutions, consists of a CO{sub 2}-rich vapor (where P{sub CO{sub 2}} {approx} P {sub internal}) and an aqueous phase containing dissolved salts and CO{sub 2}. In this study, the CO{sub 2} detection limits (DLs) using microthermometry and Raman spectroscopy are established in terms of P{sub CO{sub 2}} using synthetic H{sub 2}O-CO{sub 2} inclusions of known compositions. The purpose of the microthermometric experiments was to identify the diagnostic CO{sub 2} phase changes and determine the quantity of CO{sub 2} necessary to result in observable solid CO{sub 2} melting event in liquid-rich aqueous inclusions requires P{sub CO{sub 2}} {ge} 45 bars at 25{degrees}C. The Raman spectroscopic detection limits were investigated using a multichannel Raman spectrometer. The CO{sub 2} DLs were obtained by determining signal-to-noise ratios for both the upper and lower v{sub 1}-2v{sub 2} bands as a function of CO{sub 2} pressure (5-60 bars) over a range of integration times and incident laser power. The resulting CO{sub 2} DLs are on the order of 1 bar for the instrument used. The band splitting of the v{sub 1}-2v{sub 2} diad as a function of CO{sub 2} pressure, converted to CO{sub 2} density, was measured up to 500 bars at ambient temperature. The results are given in terms of the frequency separation between upper and lower bands and are compared to results are given in terms of the frequency separation between the upper and lower bands and are compared to results of previous studies. An analysis of the estimated errors indicates that the technique can be used to determine CO{sub 2} densities in fluid inclusions containing a homogeneous, free CO{sub 2} phase to a precision of approximately {+-}0.02 g/cm{sup 3}. 44 refs., 16 figs.

  14. In vivo Raman spectroscopic identification of premalignant lesions in oral buccal mucosa

    Science.gov (United States)

    Singh, S. P.; Deshmukh, Atul; Chaturvedi, Pankaj; Murali Krishna, C.

    2012-10-01

    Cancers of oral cavities are one of the most common malignancies in India and other south-Asian countries. Tobacco habits are the main etiological factors for oral cancer. Identification of premalignant lesions is required for improving survival rates related to oral cancer. Optical spectroscopy methods are projected as alternative/adjunct for cancer diagnosis. Earlier studies have demonstrated the feasibility of classifying normal, premalignant, and malignant oral ex-vivo tissues. We intend to evaluate potentials of Raman spectroscopy in detecting premalignant conditions. Spectra were recorded from premalignant patches, contralateral normal (opposite to tumor site), and cancerous sites of subjects with oral cancers and also from age-matched healthy subjects with and without tobacco habits. A total of 861 spectra from 104 subjects were recorded using a fiber-optic probe-coupled HE-785 Raman spectrometer. Spectral differences in the 1200- to 1800-cm-1 region were subjected to unsupervised principal component analysis and supervised linear discriminant analysis followed by validation with leave-one-out and an independent test data set. Results suggest that premalignant conditions can be objectively discriminated with both normal and cancerous sites as well as from healthy controls with and without tobacco habits. Findings of the study further support efficacy of Raman spectroscopic approaches in oral-cancer applications.

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

    Directory of Open Access Journals (Sweden)

    Liangdong Zhu

    2015-04-01

    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.

  16. [Application of Raman spectroscopic technique to the identification and investigation of Chinese ancient jades and jade artifacts].

    Science.gov (United States)

    Zhao, Hong-Xia; Gan, Fu-Xi

    2009-11-01

    Laser Raman spectroscopic technique is one of the essential methods in scientific archaeological research, which belongs to the nondestructive analysis. As a very good nondestructive analysis approach, it has not been widely applied in the research of the Chinese ancient jade artifacts. First of all in the present paper the fundamentals of laser Raman spectroscopic technique and the new research progress in this field were reviewed. Secondly, the Raman spectra of five familiar jades including nephrite (mainly composed of tremolite), Xiuyan Jade (mainly composed of serpentine), Dushan Jade (mainly composed of anorthite and Zoisite), turquoise and lapis lazuli were summarized respectively. As for an example, the Raman spectra of the four Chinese ancient jade artifacts excavated from Liangzhu Site of Zhejiang Province and Yinxu Site of Anyang in Henan Province were compared with that of the nephrite sample in Hetian of Xinjiang Province. It was shown that the Raman spectroscopic technique is a good nondestructive approach to the identification and investigation of the structures and mineral composition of Chinese ancient jade artifacts. Finally, the limitations and the foreground of this technique were discussed.

  17. Chemical Vapor Deposition Synthesis and Raman Spectroscopic Characterization of Large-Area Graphene Sheets

    Science.gov (United States)

    Liao, Chun-Da; Lu, Yi-Ying; Tamalampudi, Srinivasa Reddy; Cheng, Hung-Chieh; Chen, Yit-Tsong

    2013-10-01

    We present a chemical vapor deposition (CVD) method to catalytically synthesize large-area, transferless, single- to few-layer graphene sheets using hexamethyldisilazane (HMDS) on a SiO2/Si substrate as a carbon source and thermally evaporated alternating Ni/Cu/Ni layers as a catalyst. The as-synthesized graphene films were characterized by Raman spectroscopic imaging to identify single- to few-layer sheets. This HMDS-derived graphene layer is continuous over the entire growth substrate, and single- to trilayer mixed sheets can be up to 30 -m in the lateral dimension. With the synthetic CVD method proposed here, graphene can be grown into tailored shapes directly on a SiO2/Si surface through vapor priming of HMDS onto predefined photolithographic patterns. The transparent and conductive HMDS-derived graphene exhibits its potential for widespread electronic and opto-electronic applications.

  18. Circular dichroism and Raman spectroscopic study of the spider venom toxin V50F17

    Science.gov (United States)

    Alix, A. J. P.; Berjot, M.; Dauchez, M. A. M.; Dhalluin, C.; Lippens, G.

    1999-05-01

    V50F17 is a small 45 amino acid neurotoxin fractionated (F17) from the venom V50 of the spider Segestria florentina, which has eight cysteine residues constituting four disulfide bridges. Using circular dichroism data and vibrational Raman data at both pH 2.9 and 7.0 and preliminary NMR results obtained at pH 2.9, we derived structural information for this small protein. From these data, it is seen that it is possible to characterise well the local conformation of the disulfide bridges and the overall shape of the globular protein. Moreover, using optical spectroscopic data, it is shown that consequent local and/or global modifications are obtained on changing the pH. Results of the secondary structure states, the local conformations of the disulfide bridges, the exposure of side chains of residues and particularly of Tyr41 are discussed.

  19. Immobilization of nuclear waste: Raman Spectroscopic probing of structural changes in glass matrix

    International Nuclear Information System (INIS)

    Barium borosilicate glass used for immobilization of sulphate containing simulated high level radioactive liquid waste was prepared using conventional melt and quench method. Conventional leach test under total reflux method was used for the assessment of chemical durability of waste glass. The leaching was carried out using a conventional boiling water unit wherein powdered and screened glass sample of -16+25 BSS (850 micron) grain size was exposed to boiling distilled water for 2 years. Exposed glass specimens were subjected to Raman spectroscopic investigations to understand the structural modifications, if any, during leaching experiments. The results revealed that the leaching leads to a redistribution of bridged and non-bridged oxygen in glass. The redistribution is tentatively assigned to the possible release of structure breaking ions/atoms from the vitreous waste. (author)

  20. LED phototherapy on midpalatal suture after rapid maxilla expansion: a Raman spectroscopic study

    Science.gov (United States)

    Rosa, Cristiane B.; Habib, Fernando Antonio L.; de Araújo, Telma M.; dos Santos, Jean N.; Cangussu, Maria Cristina T.; Barbosa, Artur Felipe S.; de Castro, Isabele Cardoso V.; Soares, Luiz Guilherme P.; Pinheiro, Antonio L. B.

    2015-03-01

    A quick bone formation after maxillary expansion would reduce treatment timeand the biomodulating effects of LED light could contribute for it. The aim of this study was to analyze the effect of LED phototherapy on the acceleration of bone formation at the midpalatal suture after maxilla expansion. Thirty rats divided into 6 groups were used on the study at 2 time points - 7 days: Control; Expansion; and Expansion + LED; and 14 days: Expansion; Expansion + LED in the first week; Expansion and LED in the first and second weeks. LED irradiation occurred at every 48 h during 2 weeks. Expansion was accomplished using a spatula and maintained with a triple helicoid of 0.020" stainless steel orthodontic wire. A LED light (λ850 ± 10nm, 150mW ± 10mW, spot of 0.5cm2, t=120 sec, SAEF of 18J/cm2) was applied in one point in the midpalatal suture immediately behind the upper incisors. Near infrared Raman spectroscopic analysis of the suture region was carried and data submitted to statistical analyzes (p≤0.05). Raman spectrum analysis demonstrated that irradiation increased hydroxyapatite in the midpalatal suture after expansion. The results of this indicate that LED irradiation; have a positive biomodulation contributing to the acceleration of bone formation in the midpalatal suture after expansion procedure.

  1. Raman and 31P MAS NMR spectroscopic studies of lead phosphate glasses containing thorium oxide

    International Nuclear Information System (INIS)

    (PbO)0.5(P2O5)0.5 glasses in which part of the PbO/ P2O5 was replaced by ThO2 up to 10 mol% have been prepared by conventional melt quench method and characterized by Raman and 31P MAS NMR spectroscopic studies. Raman studies of these samples clearly revealed the existence of PO4 structural units having two non bridging oxygen atoms attached to phosphorus (PO22-). The 31P MAS NMR studies indicated the presence of two types of phosphorus structural units in both PbO -P2O5 and PbO-P2O5-ThO2 glasses, namely Q2 and Q1 (PO4 structural units with 2 and 1 bridging oxygen atoms respectively). Increase in the concentration of ThO2 at the expense of both PbO/P2O5 has been found to result in the increased amount of Q1 structural units of phosphorus, indicating that ThO2 acts as only a network modifier. ThO2 has been found to form the glassy phase with PbO-P2O5 system only up to 10 mol%. (author)

  2. Mediaeval cantorals in the Valladolid Biblioteca: FT-Raman spectroscopic study.

    Science.gov (United States)

    Edwards, H G; Farwell, D W; Rull Perez, F; Medina Garcia, J

    2001-03-01

    Raman spectroscopic studies of three mediaeval cantorals in the Biblioteca of the University of Valladolid has revealed information about the pigments used on these large manuscripts. Although executed in a simple colour palette, very pure cinnabar was used as the major colourant, offsetting the carbon black of the verses and script. A dark blue colour was achieved using a mixture of azurite (basic copper carbonate) and carbon, whereas a light blue colour was azurite alone. A grey colour was achieved using azurite, carbon particles and a calcareous 'limewash'. A yellow pigment, used sparely in the cantorals was ascribed to saffron; unusually, there was no evidence for the presence of the yellow mineral pigments orpiment, realgar and massicot. In several regions of the vellum specimens, evidence for biodeterioration was observed through the signatures of hydrated calcium oxalate. We report for the first time the Raman spectra of pigment in situ on a vellum fragment, which also shows evidence of substrate bands; comparison of black and red pigmented regions of vellum specimens has shown the presence of calcium oxalate in the black pigmented script but not in the red pigment regions, which suggests that the cinnabar in the red-pigmented regions acts as a toxic protectant for the vellum substrate against biological colonisation processes.

  3. Raman and photoelectron spectroscopic investigation of high-purity niobium materials: Oxides, hydrides, and hydrocarbons

    Science.gov (United States)

    Singh, Nageshwar; Deo, M. N.; Nand, Mangla; Jha, S. N.; Roy, S. B.

    2016-09-01

    We present investigations of the presence of oxides, hydrides, and hydrocarbons in high-purity (residual resistivity ratio, ˜300) niobium (Nb) materials used in fabrication of superconducting radio frequency (SRF) cavities for particle accelerators. Raman spectroscopy of Nb materials (as-received from the vendor as well as after surface chemical- and thermal processing) revealed numerous peaks, which evidently show the presence of oxides (550 cm-1), hydrides (1277 and 1385 cm-1: ˜80 K temperature), and groups of hydrocarbons (1096, 2330, 2710, 2830, 2868, and 3080 cm-1). The present work provides direct spectroscopic evidence of hydrides in the electropolished Nb materials typically used in SRF cavities. Raman spectroscopy thus can provide vital information about the near-surface chemical species in niobium materials and will help in identifying the cause for the performance degradation of SRF cavities. Furthermore, photoelectron spectroscopy was performed on the Nb samples to complement the Raman spectroscopy study. This study reveals the presence of C and O in the Nb samples. Core level spectra of Nb (doublet 3d5/2 and 3d3/2) show peaks near 206.6 and 209.4 eV, which can be attributed to the Nb5+ oxidation state. The core level spectra of C 1 s of the samples are dominated by graphitic carbon (binding energy, 284.6 eV), while the spectra of O 1 s are asymmetrically peaked near binding energy of ˜529 eV, and that indicates the presence of metal-oxide Nb2O5. The valence-band spectra of the Nb samples are dominated by a broad peak similar to O 2p states, but after sputtering (for 10 min) a peak appears at ˜1 eV, which is a feature of the elemental Nb atom.

  4. All chalcogenide Raman parametric Laser, Wavelength Converter and Amplifier in a Single Microwire

    CERN Document Server

    Ahmad, Raja

    2013-01-01

    Compact, power efficient and fiber compatible lasers, wavelength converters and amplifiers are vital ingredients for the future fiber optic systems and networks. Nonlinear optical effects, like Raman scattering and parametric four wave mixing, offer a way to realize such devices. Here we use a single chalcogenide microwire to realize a device that provides the functions of a Stokes Raman parametric laser, a four wave mixing anti Stokes wavelength converter, and an ultra broadband Stokes/anti Stokes Raman amplifier or supercontinuum generator. The device operation relies on ultrahigh Raman and Kerr gain (upto five orders of magnitude larger than in silica fibers), precisely engineered chromatic dispersion and high photosensitivity of the chalcogenide microwire. The Raman parametric laser operates at a record low threshold average (peak) pump power of 52 \\muW (207 mW) and a slope efficiency of >2%. A powerful anti Stokes signal is generated via the nonlinear four wave mixing process. As amplifier or the broadba...

  5. Green and red Anti-Stokes emission of U3+: LaCl3produced by infrared laser

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Anti-Stokes green and red emission from U3+: LaCl3 can be produced by infrared laser excitation at 975.3 nm, 977.7 nm and 979.4 nm at 8K. The upconversion luminescence intensity dependence upon the excitation laser power was measured and analyzed. The results show that depending on the excitation wavelength, the mechanisms responsible for the upconversion process are two-photon absorption and excited-state absorption.

  6. Stimulated Raman Scattering in Nanorod Silicon Carbide Films

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    When the film is excited by a very low excitation energy, the spontaneous Raman scattering emerges. The intensity of Raman scattering is proportional to the excitation power below the threshold excitation. When the excited power reaches the excitation threshold, the intensity of Stokes light strongly increases. Meanwhile an anti-Stokes light at 495nm and multiple order but small Stokes peaks occur. The intensity of Stokes light is much larger than that of anti-Stokes. The full width of half maximum (FWHM) of Stokes peak is reduced from 0.4nm to less than 0.2nm, the scattering angle between both Stokes and incident lights becomes less than 1°, and the angle between the Stokes and anti-Stokes lights is about 3°. When the exciting power is in excess of the threshold, anti-Stokes and multiple Raman scattering peaks reappear. These experiments can be unlimitedly repeated. From this experiment, we can exclude the possibility of spontaneous Raman scattering. It is suggested that the nanorods are a quantum line dimension having a large surface. There will be Raman differential scattering section so long as the nanorod films become very strong scattering media; the surface-enhanced Raman scattering will be produced, the nanorod films of SiC will form a strong multiple scattering resonance cavities so as to form the stimulated Raman scattering oscillation.

  7. Quantitative Chemical Imaging with Multiplex Stimulated Raman Scattering Microscopy

    OpenAIRE

    Fu, Dan; Lu, Fake; Zhang, Xu; Freudiger, Christian Wilhelm; Pernik, Douglas R.; Holtom, Gary; Xie, Xiaoliang Sunney

    2012-01-01

    Stimulated Raman scattering (SRS) microscopy is a newly developed label-free chemical imaging technique that overcomes the speed limitation of confocal Raman microscopy while avoiding the nonresonant background problem of coherent anti-Stokes Raman scattering (CARS) microscopy. Previous demonstrations have been limited to single Raman band measurements. We present a novel modulation multiplexing approach that allows real-time detection of multiple species using the fast Fourier transform. ...

  8. Raman Spectroscopy and Microscopy of Individual Cells andCellular Components

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-05-15

    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.

  9. Raman spectroscopic evaluation of the dissemination of road de-icers in the environment

    Science.gov (United States)

    Durickovic, Ivana; Marchetti, Mario; Suaire, Remi; Derombise, Guillaume

    2013-04-01

    Raman spectroscopy is nowadays a well established technique for the investigation of the molecular structure of a substance (solid, liquid or gas) through the study of its vibrational properties. This technique has been shown as particularly adapted for the characterization of water and aqueous solutions. The ERA 31 of the CÉTÉ de l'Est is developing methods based on that technique for domains such as water pollution detection and pollutant dissemination, mainly linked to transport infrastructures. A specific application of the Raman spectroscopy is the monitoring of the road de-icing materials' evolution after application on the road's surface. Indeed, in order to avoid traffic disruption during winter, roads and airports are the subject of a specific maintenance based on the application of de-icing materials. However, these chemicals are transported out of the roads, and end up either in the surrounding environment (splashed out by the vehicles or blown away by the wind) or in ponds used for road water runoff remediation and flow control (by flows after precipitations). The first aspect of the road de-icing surveillance is therefore their follow-up in the transport infrastructure's surrounding environment. A spectroscopic tool was hence developed for the measurement of these products on roads and in water located next to transport infrastructures, and adapted for the measurement on soils. The second aspect concerns the tracking of the de-icing material in the detention ponds. The instrumentation of a specific pond has been set in order to determine the road de-icing material's evolution and influence on the pond's environmental media (water, soil and vegetation). The goal is to evaluate in what way and how long, the road de-icer will spread in a detention pond. It will permit us to estimate the pond retention period, as well as its remediation efficiency.

  10. Quantum-statistical theory of Raman scattering processes

    CERN Document Server

    Miranowicz, Adam

    2011-01-01

    Raman scattering from a great number of phonon modes is described from a quantum-statistical point of view within the standing-wave model. The master equation for the completely quantum case, including laser pump depletion and stochastic coupling of Stokes and anti-Stokes modes, is derived and converted to classical equations: either into a generalized Fokker-Planck equation and an equation of motion for the characteristic function or into the master equation in Fock representation. These two approaches are developed both in linear and nonlinear regime. A detailed analysis of scattering into Stokes and anti-Stokes modes in linear regime, i.e., under parametric approximation, is presented. The existence of s-parametrized quasiprobability distributions, in particular the Glauber-Sudarshan P-function, is investigated. An analysis of Raman scattering into separate Stokes and anti-Stokes modes in nonlinear regime, thus including pump depletion, is given. The master equation in Fock representation is solved exactly...

  11. Determination of drug content in semisolid formulations by non-invasive spectroscopic methods: FTIR - ATR, - PAS, - Raman and PDS

    Energy Technology Data Exchange (ETDEWEB)

    Gotter, B; Hein, J; Neubert, R H H [Institute of Pharmacy, Martin-Luther-University, Wolfgang-Langenbeck-Str. 4, 06120 Halle/Saale (Germany); Faubel, W; Heissler, St, E-mail: bernhard.gotter@pharmazie.uni-halle.d [Institute of Functional Interfaces, Karlsruhe Institute of Technology, Herrmann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2010-03-01

    This study elucidates the potential use of photothermal deflection spectroscopy (PDS), FTIR photoacoustic (FTIR-PAS), FT Raman, and FTIR-attenuated total reflection (FTIR-ATR) spectroscopy as analytical tools for investigating the drug content in semisolid formulations. Regarding the analytical parameters, this study demonstrates the photothermal beam deflection to be definitely comparable to well established spectroscopic methods for this purpose. The correlation coefficients range from 0.990 to 0.999. Likewise, repeatability and limit of detection are comparable.

  12. X-ray and Raman spectroscopic studies on Ru substituted LiMn2O4

    International Nuclear Information System (INIS)

    Phase pure Ru substituted LiMn2O4 charge frustrated spinel compounds have been synthesized. Ru substitution for Mn is possible only up to 7.5%. Powder diffraction measurements confirm sustenance of charge frustrated cubic phase with space group Fd3m upon substitution of Ru for Mn. An increase in lattice parameter has been observed indicating replacement of Mn as Ru3+ or Ru4+ rather than Ru5+. Raman spectroscopic measurements show that the crystal structure is robust against an increase of laser power and the observed bands show an expected red shift. In the case of Ru substituted LiMn2O4, the A1g symmetric stretching mode, the F(1)2g and the F(2)2g symmetric bending modes identified with the Mn-O octahedra show a red shift up to Ru 0.075 and at higher Ru concentrations, revert back to the frequency corresponding to the pristine LiMn2O4

  13. Raman spectroscopic identification of arsenate minerals in situ at outcrops with handheld (532 nm, 785 nm) instruments.

    Science.gov (United States)

    Culka, Adam; Kindlová, Helena; Drahota, Petr; Jehlička, Jan

    2016-02-01

    Minerals are traditionally identified under field conditions by experienced mineralogists observing the basic physical properties of the samples. Under laboratory conditions, a plethora of techniques are commonly used for identification of the geological phases based on their structural and spectroscopic parameters. In this area, Raman spectrometry has become a useful tool to complement the more widely applied XRD. Today, however, there is an acute need for a technique for unambiguous in situ identification of minerals, within the geological as well as planetary/exobiology realms. With the potential for miniaturization, Raman spectroscopy can be viewed as a practical technique to achieve these goals. Here, for the first time, the successful application of handheld Raman spectrometers is demonstrated to detect and discriminate arsenic phases in the form of earthy aggregates. The Raman spectroscopic analyses of arsenate minerals were performed in situ using two handheld instruments, using 532 and 785 nm excitation. Bukovskýite, kaňkite, parascorodite, and scorodite were identified from Kaňk near Kutná Hora, CZE; kaňkite, scorodite, and zýkaite were identified at the Lehnschafter gallery in an old silver mine at Mikulov near Teplice, Bohemian Massif, CZE. PMID:26523686

  14. Coherent Raman spectro-imaging with laser frequency combs.

    Science.gov (United States)

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

    2013-10-17

    Advances in optical spectroscopy and microscopy have had a profound impact throughout the physical, chemical and biological sciences. One example is coherent Raman spectroscopy, a versatile technique interrogating vibrational transitions in molecules. It offers high spatial resolution and three-dimensional sectioning capabilities that make it a label-free tool for the non-destructive and chemically selective probing of complex systems. Indeed, single-colour Raman bands have been imaged in biological tissue at video rates by using ultra-short-pulse lasers. However, identifying multiple, and possibly unknown, molecules requires broad spectral bandwidth and high resolution. Moderate spectral spans combined with high-speed acquisition are now within reach using multichannel detection or frequency-swept laser beams. Laser frequency combs are finding increasing use for broadband molecular linear absorption spectroscopy. Here we show, by exploring their potential for nonlinear spectroscopy, that they can be harnessed for coherent anti-Stokes Raman spectroscopy and spectro-imaging. The method uses two combs and can simultaneously measure, on the microsecond timescale, all spectral elements over a wide bandwidth and with high resolution on a single photodetector. Although the overall measurement time in our proof-of-principle experiments is limited by the waiting times between successive spectral acquisitions, this limitation can be overcome with further system development. We therefore expect that our approach of using laser frequency combs will not only enable new applications for nonlinear microscopy but also benefit other nonlinear spectroscopic techniques. PMID:24132293

  15. CARS and Raman spectroscopy of function-related conformational changes of chymotrypsin

    NARCIS (Netherlands)

    Brandt, N.N.; Chikishev, A.Yu.; Greve, J.; Koroteev, N.I.; Otto, C.; Sakodynskaya, I.K.

    2000-01-01

    We report on the comparative analysis of the conformation-sensitive bands of free enzyme (chymotrypsin), liganded enzyme (chymotrypsin anthranilate) and enzyme complex with 18-crown-6. The studies were carried out by Raman scattering spectroscopy and polarization-sensitive coherent anti-Stokes Raman

  16. Enhancing the efficiency of silicon Raman converters

    Science.gov (United States)

    Vermeulen, Nathalie; Sipe, John E.; Thienpont, Hugo

    2010-05-01

    We propose a silicon ring Raman converter in which the spatial variation of the Raman gain along the ring for TE polarization is used to quasi-phase-match the CARS process. If in addition the pump, Stokes, and anti-Stokes waves involved in the CARS interaction are resonantly enhanced by the ring structure, the Stokes-to-anti-Stokes conversion efficiency can be increased by at least four orders of magnitude over that of one-dimensional perfectly phase-matched silicon Raman converters, and can reach values larger than unity with relatively low input pump intensities. These improvements in conversion performance could substantially expand the practical applicability of the CARS process for optical wavelength conversion.

  17. The biocompatibility of carbon hydroxyapatite/β-glucan composite for bone tissue engineering studied with Raman and FTIR spectroscopic imaging.

    Science.gov (United States)

    Sroka-Bartnicka, Anna; Kimber, James A; Borkowski, Leszek; Pawlowska, Marta; Polkowska, Izabela; Kalisz, Grzegorz; Belcarz, Anna; Jozwiak, Krzysztof; Ginalska, Grazyna; Kazarian, Sergei G

    2015-10-01

    The spectroscopic approaches of FTIR imaging and Raman mapping were applied to the characterisation of a new carbon hydroxyapatite/β-glucan composite developed for bone tissue engineering. The composite is an artificial bone material with an apatite-forming ability for the bone repair process. Rabbit bone samples were tested with an implanted bioactive material for a period of several months. Using spectroscopic and chemometric methods, we were able to determine the presence of amides and phosphates and the distribution of lipid-rich domains in the bone tissue, providing an assessment of the composite's bioactivity. Samples were also imaged in transmission using an infrared microscope combined with a focal plane array detector. CaF2 lenses were also used on the infrared microscope to improve spectral quality by reducing scattering artefacts, improving chemometric analysis. The presence of collagen and lipids at the bone/composite interface confirmed biocompatibility and demonstrate the suitability of FTIR microscopic imaging with lenses in studying these samples. It confirmed that the composite is a very good background for collagen growth and increases collagen maturity with the time of the bone growth process. The results indicate the bioactive and biocompatible properties of this composite and demonstrate how Raman and FTIR spectroscopic imaging have been used as an effective tool for tissue characterisation.

  18. Use of a charge-coupled device camera for broadband coherent anti-Stokes Raman scattering measurements.

    Science.gov (United States)

    Rakestraw, D J; Lucht, R P; Dreier, T

    1989-10-01

    The use of an unintensified charge-coupled device (CCD) camera for the acquisition of broadband CARS signals is demonstrated. The CCD camera offers significant advantages compared to intensified, linear photodiode array (PDA) detectors that are generally used for broadband CARS measurements. These advantages include higher spectral resolution and improved instrument function, larger dynamic range, and a 2-D format. PMID:20555836

  19. Distinguishing non-resonant four-wave-mixing noise in coherent stokes and anti-stokes Raman scattering

    Science.gov (United States)

    Marks, Daniel L. (Inventor); Boppart, Stephen A. (Inventor)

    2009-01-01

    A method of examining a sample comprises exposing the sample to a pump pulse of electromagnetic radiation for a first period of time, exposing the sample to a stimulant pulse of electromagnetic radiation for a second period of time which overlaps in time with at least a portion of the first exposing, to produce a signal pulse of electromagnetic radiation for a third period of time, and interfering the signal pulse with a reference pulse of electromagnetic radiation, to determine which portions of the signal pulse were produced during the exposing of the sample to the stimulant pulse. The first and third periods of time are each greater than the second period of time.

  20. Seeing the vibrational breathing of a single molecule through time-resolved coherent anti-Stokes Raman scattering

    OpenAIRE

    Yampolsky, S; Fishman, DA; Dey, S; Hulkko, E.; Banik, M; Potma, EO; Apkarian, VA

    2014-01-01

    The motion of chemical bonds within molecules can be observed in real time, in the form of vibrational wavepackets prepared and interrogated through ultrafast nonlinear spectroscopy. Such nonlinear optical measurements are commonly performed on large ensembles of molecules, and as such, are limited to the extent that ensemble coherence can be maintained. Here, we describe vibrational wavepacket motion on single molecules, recorded through time-resolved, surface-enhanced, coh...

  1. Silicon nanocrystals with high boron and phosphorus concentration hydrophilic shell—Raman scattering and X-ray photoelectron spectroscopic studies

    Energy Technology Data Exchange (ETDEWEB)

    Fujii, Minoru, E-mail: fujii@eedept.kobe-u.ac.jp; Sugimoto, Hiroshi; Hasegawa, Masataka; Imakita, Kenji [Department of Electrical and Electronic Engineering, Graduate School of Engineering, Kobe University, Rokkodai, Nada, Kobe 657-8501 (Japan)

    2014-02-28

    Boron (B) and phosphorus (P) codoped silicon (Si) nanocrystals, which exhibit very wide range tunable luminescence due to the donor to acceptor transitions and can be dispersed in polar liquids without organic ligands, are studied by Raman scattering and X-ray photoelectron spectroscopies. Codoped Si nanocrystals exhibit a Raman spectrum significantly different from those of intrinsic ones. First, the Raman peak energy is almost insensitive to the size and is very close to that of bulk Si crystal in the diameter range of 2.7 to 14 nm. Second, the peak is much broader than that of intrinsic ones. Furthermore, an additional broad peak, the intensity of which is about 20% of the main peak, appears around 650 cm{sup −1}. The peak can be assigned to local vibrational modes of substitutional B and B-P pairs, B clusters, B-interstitial clusters, etc. in Si crystal. The Raman and X-ray photoelectron spectroscopic studies suggest that a crystalline shell heavily doped with these species is formed at the surface of a codoped Si nanocrystal and it induces the specific properties, i.e., hydrophilicity, high-stability in water, high resistance to hydrofluoric acid, etc.

  2. Fourier transform Raman spectroscopic characterisation of cells of the plant-associated soil bacterium Azospirillum brasilense Sp7

    Science.gov (United States)

    Kamnev, A. A.; Tarantilis, P. A.; Antonyuk, L. P.; Bespalova, L. A.; Polissiou, M. G.; Colina, M.; Gardiner, P. H. E.; Ignatov, V. V.

    2001-05-01

    Structural and compositional features of bacterial cell samples and of lipopolysaccharide-protein complex isolated from the cell surface of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp7) were characterised using Fourier transform (FT) Raman spectroscopy. The structural spectroscopic information obtained is analysed and considered together with analytical data on the content of metal cations (Co 2+, Cu 2+ and Zn 2+) in the bacterial cells grown in a standard medium as well as in the presence of each of the cations (0.2 mM). The latter, being taken up by bacterial cells from the culture medium in significant amounts, were shown to induce certain metabolic changes in the bacterium revealed in FT-Raman spectra, which is discussed from the viewpoint of bacterial response to environmental stresses.

  3. Comparative FT-Raman, FT-IR and colour shifts spectroscopic evaluation of gamma irradiated experimental models of oil paintings

    International Nuclear Information System (INIS)

    Complete text of publication follows. The present study follows the changes of gamma irradiated historic pigments and experimental models of oil paintings with non-destructive and non-contact spectroscopic analytical techniques which are the only ones accepted by the conservators/restorers community. Molecular structure characterization was performed by FT-IR / Raman spectroscopy using a Bruker Vertex 70 class equipped with two mobile probes: a MIR fibre module for MIR probes (with LN2 cooled detector) and a Raman RAM II module (LN2 Ge detector) with a RAMPROBE fibre. Colour was measured by a portable reflectance spectrophotometer (Miniscan XE Plus, HunterLab) in diffuse/8 deg geometry with a beam diameter of 4 mm and specular component included. Correlations between colour shifts and changes in molecular structure induced by gamma irradiation were further investigated.

  4. Interaction between indium tin oxide nanoparticles and cytochrome c: A surface-enhanced Raman scattering and absorption spectroscopic study

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yimin, E-mail: yangyimin@seu.edu.cn, E-mail: tqiu@seu.edu.cn; Du, Deyang; Fan, Jiyang; Qiu, Teng, E-mail: yangyimin@seu.edu.cn, E-mail: tqiu@seu.edu.cn [Department of Physics, Southeast University, Nanjing 211189 (China); Kong, Fan [School of Chemistry and Chemical Engineering, Southeast University, Nanjing 211189 (China)

    2015-06-28

    Indium-tin-oxide (ITO) nanoparticles were annealed in vacuum or reducing atmosphere to obtain different surface structures and investigate their influence on the adsorptive character and conformation of cytochrome c (Cyt c) molecule. Annealing-induced morphometric or structural changes of ITO nanoparticles were characterized by instruments of transmission electron microscopy, x-ray diffraction, and Raman scattering. Semiconductor ITO nanoparticle-enhanced Raman scattering of Cyt c was observed and the enhanced efficiency was found to closely depend on the surface structures which control the adsorbance of buffer anions needed for Cyt c loading. Direct electron transfer between Cyt c and ITO surface at the moment of molecular elastic collision was found and a reverse electron transfer process for O-terminated surface and metal-terminated surface was observed, according to absorption spectroscopic measurement on the residual solution.

  5. Resonance raman spectroscopic study of alumina-supported vanadium oxide catalysts with 220 and 287 nm excitation.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, H. S.; Stair, P. C.; Chemical Sciences and Engineering Division; Northwestern Univ.

    2009-01-01

    We present detailed resonance Raman spectroscopic results excited at 220 and 287 nm for alumina-supported VO{sub x} catalysts. The anharmonic constant, harmonic wavenumber, anharmonic force constant, bond dissociation energy, and bond length change in the excited state for double bonded V{double_bond}O and single bonded V-O were obtained from fundamental and overtone frequencies. Totally symmetric and nontotally symmetric modes could be discerned and assigned on the basis of the overtone and combination progressions found in the resonance Raman spectra. Selective resonance enhancement of two different vibrational modes with two different excitation wavelengths was observed. This allowed us to establish a linear relationship between charge transfer energy and VO bond length and, consequently, to assign the higher-energy charge transfer band centered around 210?250 nm in the UV?vis spectra to the V{double_bond}O transition.

  6. Lightweight Raman spectroscope using time-correlated photon-counting detection

    OpenAIRE

    Meng, Zhaokai; Petrov, Georgi I.; Cheng, Shuna; Jo, Javier A.; Lehmann, Kevin K; Vladislav V. Yakovlev; Scully, Marlan O.

    2015-01-01

    Raman spectroscopy is an important tool in understanding chemical components of various materials. However, the excessive weight and energy consumption of a conventional CCD-based spectrometer forbids its applications in space-based instruments, including unmanned aircraft vehicles (UAVs) and Mars/Moon rovers. In this article, we present a lightweight and energy-efficient hyperspectral Raman measurement system. This technique allows UAVs and space vehicles to carry Raman spectrometers without...

  7. Raman and surface enhanced Raman spectroscopic studies of specific, small molecule activator of histone acetyltransferase p300

    Science.gov (United States)

    Kundu, Partha P.; Pavan Kumar, G. V.; Mantelingu, Kempegowda; Kundu, Tapas K.; Narayana, Chandrabhas

    2011-07-01

    We report for the first time, the Raman and surface enhanced Raman scattering (SERS) studies of N-(4-chloro-3-trifluoromethyl-phenyl)-2-ethoxy-benzamide (CTB). This molecule is specific activator of human histone acetyltransferase (HAT), p300, and serves as lead molecule to design anti-neoplastic therapeutics. A detailed Raman and SERS band assignments have been performed for CTB, which are compared with the density functional theory calculations. The observed red shift of N sbnd H stretching frequency from the computed wavenumber indicates the weakening of N sbnd H bond resulting from proton transfer to the neighboring oxygen atom. We observe Ag sbnd N vibrational mode at 234 cm -1 in SERS of CTB. This indicates there is a metal-molecule bond leading to chemical enhancement in SERS. We also observe, enhancement in the modes pertaining to substituted benzene rings and methyl groups. Based on SERS analysis we propose the adsorption sites and the orientation of CTB on silver surface.

  8. Multiferroic CuCrO2 under High Pressure: In-Situ X-Ray Diffraction and Raman Spectroscopic Studies

    OpenAIRE

    Garg, Alka B.; Mishra, A. K.; Pandey, K. K.; Sharma, Surinder M

    2014-01-01

    The compression behavior of delafossite compound CuCrO2 has been investigated by in-situ x-ray diffraction and Raman spectroscopic measurements upto 23.2 and 34 GPa respectively. X-ray diffraction data shows the stability of ambient rhombohedral structure upto ~ 23 GPa. Material shows large anisotropy in axial compression with c-axis compressibility, c= 1.2610-3(1) GPa-1 and a-axis compressibility, a= 8.9010-3(6) GPa-1. Our XRD data shows an irreversible broadening of diffraction peaks. Press...

  9. Continuous statistical modelling for rapid detection of adulteration of extra virgin olive oil using mid infrared and Raman spectroscopic data.

    Science.gov (United States)

    Georgouli, Konstantia; Martinez Del Rincon, Jesus; Koidis, Anastasios

    2017-02-15

    The main objective of this work was to develop a novel dimensionality reduction technique as a part of an integrated pattern recognition solution capable of identifying adulterants such as hazelnut oil in extra virgin olive oil at low percentages based on spectroscopic chemical fingerprints. A novel Continuous Locality Preserving Projections (CLPP) technique is proposed which allows the modelling of the continuous nature of the produced in-house admixtures as data series instead of discrete points. The maintenance of the continuous structure of the data manifold enables the better visualisation of this examined classification problem and facilitates the more accurate utilisation of the manifold for detecting the adulterants. The performance of the proposed technique is validated with two different spectroscopic techniques (Raman and Fourier transform infrared, FT-IR). In all cases studied, CLPP accompanied by k-Nearest Neighbors (kNN) algorithm was found to outperform any other state-of-the-art pattern recognition techniques. PMID:27664692

  10. Book Review: Reiner Salzer and Heinz W. Siesler (Eds.): Infrared and Raman spectroscopic imaging, 2nd ed

    International Nuclear Information System (INIS)

    This second edition of 'Infrared and Raman Spectroscopic Imaging' propels practitioners in that wide-ranging field, as well as other readers, to the current state of the art in a well-produced and full-color, completely revised and updated, volume. This new edition chronicles the expanded application of vibrational spectroscopic imaging from yesterday's time-consuming point-by-point buildup of a hyperspectral image cube, through the improvements afforded by the addition of focal plane arrays and line scan imaging, to methods applicable beyond the diffraction limit, instructs the reader on the improved instrumentation and image and data analysis methods, and expounds on their application to fundamental biomedical knowledge, food and agricultural surveys, materials science, process and quality control, and many others

  11. Nonlinear optical imaging and Raman microspectrometry of the cell nucleus throughout the cell cycle.

    Science.gov (United States)

    Pliss, Artem; Kuzmin, Andrey N; Kachynski, Aliaksandr V; Prasad, Paras N

    2010-11-17

    Fundamental understanding of cellular processes at molecular level is of considerable importance in cell biology as well as in biomedical disciplines for early diagnosis of infection and cancer diseases, and for developing new molecular medicine-based therapies. Modern biophotonics offers exclusive capabilities to obtain information on molecular composition, organization, and dynamics in a cell by utilizing a combination of optical spectroscopy and optical imaging. We introduce here a combination of Raman microspectrometry, together with coherent anti-Stokes Raman scattering (CARS) and two-photon excited fluorescence (TPEF) nonlinear optical microscopy, to study macromolecular organization of the nucleus throughout the cell cycle. Site-specific concentrations of proteins, DNA, RNA, and lipids were determined in nucleoli, nucleoplasmic transcription sites, nuclear speckles, constitutive heterochromatin domains, mitotic chromosomes, and extrachromosomal regions of mitotic cells by quantitative confocal Raman microspectrometry. A surprising finding, obtained in our study, is that the local concentration of proteins does not increase during DNA compaction. We also demonstrate that postmitotic DNA decondensation is a gradual process, continuing for several hours. The quantitative Raman spectroscopic analysis was corroborated with CARS/TPEF multimodal imaging to visualize the distribution of protein, DNA, RNA, and lipid macromolecules throughout the cell cycle.

  12. Raman spectroscopic characterization of ZrO2 and yttrium stabilized zirconias

    DEFF Research Database (Denmark)

    Kjerulf-Jensen, N.; Berg, Rolf W.; Poulsen, Finn Willy

    1996-01-01

    forward. The spectral features of the Raman spectra do furthermore not only depend on the phase composition, but also depend on the frequency of the excitation, temperature of experiment and texture/orientation of zirconia crystallites under investigation. These effects are illustrated by Raman spectra...

  13. Using Raman spectroscopic imaging for non-destructive analysis of filler distribution in chalk filled polypropylene

    DEFF Research Database (Denmark)

    Boros, Evelin; Porse, Peter Bak; Nielsen, Inga;

    2016-01-01

    A feasibility study on using Raman spectral imaging for visualization and analysis of filler distribution in chalk filled poly-propylene samples has been carried out. The spectral images were acquired using a Raman spectrometer with 785 nm light source.Eight injection-molded samples with...

  14. Raman spectroscopic characterization of the core-rim structure in reaction bonded boron carbide ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Jannotti, Phillip; Subhash, Ghatu, E-mail: subhash@ufl.edu [Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, Florida 32611 (United States); Zheng, James Q.; Halls, Virginia [Program Executive Office—Soldier Protection and Individual Equipment, US Army, Fort Belvoir, Virginia 22060 (United States); Karandikar, Prashant G.; Salamone, S.; Aghajanian, Michael K. [M-Cubed Technologies, Inc., Newark, Delaware 19711 (United States)

    2015-01-26

    Raman spectroscopy was used to characterize the microstructure of reaction bonded boron carbide ceramics. Compositional and structural gradation in the silicon-doped boron carbide phase (rim), which develops around the parent boron carbide region (core) due to the reaction between silicon and boron carbide, was evaluated using changes in Raman peak position and intensity. Peak shifting and intensity variation from the core to the rim region was attributed to changes in the boron carbide crystal structure based on experimental Raman observations and ab initio calculations reported in literature. The results were consistent with compositional analysis determined by energy dispersive spectroscopy. The Raman analysis revealed the substitution of silicon atoms first into the linear 3-atom chain, and then into icosahedral units of the boron carbide structure. Thus, micro-Raman spectroscopy provided a non-destructive means of identifying the preferential positions of Si atoms in the boron carbide lattice.

  15. Spectroscopic detection of chemotherapeutics and antioxidants

    Science.gov (United States)

    Latka, Ines; Grüner, Roman; Matthäus, Christian; Dietzek, Benjamin; Werncke, W.; Lademann, Jürgen; Popp, Jürgen

    2012-06-01

    The hand-foot-syndrome presents a severe dermal side-effect of chemotherapeutic cancer treatment. The cause of this side-effect is the elimination of systemically administered chemotherapeutics with the sweat. Transported to the skin surface, the drugs subsequently penetrate into the skin in the manner of topically applied substances. Upon accumulation of the chemotherapeutics in the skin the drugs destroy cells and tissue - in the same way as they are supposed to act in cancer cells. Aiming at the development of strategies to illuminate the molecular mechanism underlying the handfoot- syndrome (and, in a second step, strategies to prevent this severe side-effect), it might be important to evaluate the concentration and distribution of chemotherapeutics and antioxidants in the human skin. The latter can be estimated by the carotenoid concentration, as carotenoids serve as marker substances for the dermal antioxidative status.Following the objectives outlined above, this contribution presents a spectroscopic study aiming at the detection and quantification of carotenoids and selected chemotherapeutics in human skin. To this end, spontaneous Raman scattering and coherent anti-Stokes Raman scattering (CARS) microspectroscopy are combined with two-photon excited fluorescence. While the latter technique is Please verify that (1) all pages are present, (2) all figures are correct, (3) all fonts and special characters are correct, and (4) all text and figures fit within the red margin lines shown on this review document. Complete formatting information is available at http://SPIE.org/manuscripts Return to your MySPIE To Do List at http://myspie.org and approve or disapprove this submission. Your manuscript will not be published without this approval.restricted to the detection of fluorescent chemotherapeutics, e.g., doxorubicin, the vibrational spectroscopic techniques can - in principle - be applied to any type of analyte molecules. Furthermore, we will present the

  16. Laser Cooling Using Anti-Stokes Fluorescencein Yb3+-Doped Fluorozirconate Glasses

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The fluorozirconate glasses ZBLANP( ZrF4-BaF2-LaF3-AlF3-NaF-PbF2) doped with different Yb3+ concentration were prepared. The Raman spectra and absorption spectra are measured to substantiate the existence of phonon-assisted emission. After analyzing the normalized absorption spectra of samples with different Yb3+-doped concentration, we calculated the maximum cooling effect in the 3 wt% Yb3+-doped sample pumped at 1 012.5 nm. The corresponding cooling capability is about -4.09 ℃/W and the cooling efficiency reaches 1.76%.

  17. High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues

    CERN Document Server

    Camp, Charles H; Heddleston, John M; Hartshorn, Christopher M; Walker, Angela R Hight; Rich, Jeremy N; Lathia, Justin D; Cicerone, Marcus T

    2014-01-01

    We have developed a coherent Raman imaging platform using broadband coherent anti-Stokes Raman scattering (BCARS) that provides an unprecedented combination of speed, sensitivity, and spectral breadth. The system utilizes a unique configuration of laser sources that probes the Raman spectrum over 3,000 cm$^{-1}$ and generates an especially strong response in the typically weak Raman "fingerprint" region through heterodyne amplification of the anti-Stokes photons with a large nonresonant background (NRB) while maintaining high spectral resolution of $<$ 13 cm$^{-1}$. For histology and pathology, this system shows promise in highlighting major tissue components in a non-destructive, label-free manner. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues and interfaces between xenograft brain tumors and the surrounding healthy brain matter.

  18. FT-IR and Micro-Raman spectroscopic studies of archaeological potteries recently excavated in Poompuhar, Tamilnadu, India

    Science.gov (United States)

    Kiruba, S.; Ganesan, S.

    2015-06-01

    Ancient ceramics are the abundant artifacts that give the knowledge of the past societies. Therefore it is of great importance to acquire knowledge about the chemical composition of the clay in archaeological artifacts. The spectroscopic techniques represent one of the most powerful tools to investigate the structure of all the materials and chemical composition of the cultural object like potteries. An attempt has been made in the present work to estimate the firing temperature of the archaeological pottery shreds excavated from the archaeological site Poompuhar in the state of Tamilnadu in India. The firing temperature of the archaeological pottery shreds were estimated by recording the corresponding FT-IR spectra in the range 4000-450 cm-1 and Micro Raman spectra in the range 1800-400 cm-1. The clay mineral present in the pottery samples are identified through FT-IR method and was confirmed with Micro Raman spectroscopy as both are complement to each other. The major primary mineral present in the samples is Kaolinite and the secondary mineral present is quartz and the accessory minerals present in the samples are hematite, magnetite and feldspar. The results of Raman spectra showed that the potters of this site used a mixture of clays as raw materials. The firing temperature for some of the samples did not exceed 800 °C which suggests the use of open fire.

  19. A microfluidic surface enhanced Raman spectroscopic biosensor using aptamer functionalized nanopillars

    DEFF Research Database (Denmark)

    Yang, J.; Palla, M.; Bosco, F. G.;

    2013-01-01

    This paper presents a microchip incorporating an aptamer-functionalized nanopillar substrate, enabling the specific detection of low-abundance biomolecules using surface enhanced Raman spectroscopy (SERS). In a temperature controlled microchamber, aptamers immobilized on the nanostructure surface...

  20. Raman Spectroscopic Studies on L-histidine, aniline Doped Triglycine Sulphate Single Crystals

    Science.gov (United States)

    Benial, A. Milton Franklin; Ramakrishnan, V.; Parameswari, A.

    2015-02-01

    Single crystals of triglycine sulphate (TGS) doped with L-histidine and aniline were studied by Raman Spectroscopy. The structure and symmetry of molecules, the nature of bonding and the effect of crystalline field on molecular vibrations were studied for pure and doped TGS. The characteristic group frequencies were identified and analysed for H2SO4 and glycine. The skeletal motion, lattice vibrational peaks were observed in the low wavenumber region. The site symmetry effect and the correlation field effect were studied from the splitting of vibrational bands. The observed Raman shift towards higher wave number region reveals that the symmetry reduction in doped TGS crystals. The broadening of Raman spectral line showed that a decrease in the hardness value for the doped crystals. Comparative studies of the Raman Spectra of pure TGS and doped TGS were also carried out.

  1. A Raman spectroscopic study of arsenite and thioarsenite species in aqueous solution at 25°C

    Directory of Open Access Journals (Sweden)

    Janecky David R

    2002-02-01

    Full Text Available The Raman spectra of thioarsenite and arsenite species in aqueous solution were obtained at room temperature. Solutions at constant ΣAs + ΣS of 0.1 and 0.5 mol kg-1 were prepared with various ΣS/ΣAs ratios (0.1–9.0 and pH values (~7–13.2. Our data suggest that the speciation of As under the conditions investigated is more complicated than previously thought. The Raman measurements offer evidence for at least six separate S-bearing As species whose principal bands are centered near 365, 385, 390, 400, 415 and 420 cm-1. The data suggest that at least two different species may give rise to bands at 385 cm-1, bringing the probable minimum number of species to seven. Several additional species are possible but could not be resolved definitively. In general, the relative proportions of these species are dependent on total As concentration, ΣS/ΣAs ratio and pH. At very low ΣS/ΣAs ratios we also observe Raman bands attributable to the dissociation products of H3AsO3(aq. Although we were unable to assign precise stoichiometries for the various thioarsenite species, we were able to map out general pH and ΣS/ΣAs conditions under which the various thioarsenite and arsenite species are predominant. This study provides a basis for more detailed Raman spectroscopic and other types of investigations of the nature of thioarsenite species.

  2. A pH dependent Raman and surface enhanced Raman spectroscopic studies of citrazinic acid aided by theoretical calculations.

    Science.gov (United States)

    Sarkar, Sougata; Chowdhury, Joydeep; Dutta, Soumen; Pal, Tarasankar

    2016-12-01

    A pH dependent normal Raman scattering (NRS) and surface enhanced Raman scattering (SERS) spectral patterns of citrazinic acid (CZA), a biologically important molecule, have been investigated. The acid, with different pKa values (~4 and ~11) for the two different functional groups (-COOH and -OH groups), shows interesting range of color changes (yellow at pH~14 and brown at pH~2) with the variation in solution pH. Thus, depending upon the pH of the medium, CZA molecule can exist in various protonated and/or deprotonated forms. Here we have prescribed the existence different possible forms of CZA at different pH (Forms "C", "H" and "Dprot" at pH~14 and Forms "A", "D", and "P" at pH~2 respectively). The NRS spectra of these solutions and their respective SERS spectra over gold nanoparticles were recorded. The spectra clearly differ in their spectral profiles. For example the SERS spectra recorded with the CZA solution at pH~2 shows blue shift for different bands compared to its NRS window e.g. 406 to 450cm(-1), 616 to 632cm(-1), 1332 to 1343cm(-1) etc. Again, the most enhanced peak at ~1548cm(-1) in NRS while in the SERS window this appears at ~1580cm(-1). Similar observation was also made for CZA at pH~14. For example, the 423cm(-1) band in the NRS profile experience a blue shift and appears at ~447cm(-1) in the SERS spectrum as well as other bands at ~850, ~1067 and ~1214cm(-1) in the SERS window are markedly enhanced. It is also worth noting that the SERS spectra at the different pH also differ from each other. These spectral differences indicate the existence of various adsorptive forms of the CZA molecule depending upon the pH of the solution. Therefore based on the experimental findings we propose different possible molecular forms of CZA at different pH (acidic and alkaline) conditions. For example forms 'A', 'D' and 'P' existing in acidic pH (pH~2) and three other deprotonated forms 'C', 'H' and 'Dprot' in alkaline pH (pH~14). The DFT calculations for these

  3. Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane

    Energy Technology Data Exchange (ETDEWEB)

    Jewett, J.R., Fluor Daniel Hanford

    1997-02-24

    Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

  4. Raman Spectroscopic Studies of Clathrate Hydrate Formation in the Presence of Hydrophobized Particles.

    Science.gov (United States)

    Li, Huijuan; Stanwix, Paul; Aman, Zachary; Johns, Michael; May, Eric; Wang, Liguang

    2016-01-28

    In the present work, Raman spectroscopy was used to study the structure of water molecules in the vicinity of glass particles with different hydrophobicity, immersed in water and in tetrahydrofuran and cyclopentane hydrates. The glass particle surfaces were clean (hydrophilic), coated with N,N-dimethyl-N-octadecyl-3-aminopropyl trimethoxysilyl chloride (partially hydrophobic), or coated with octadecyltrichlorosilane (hydrophobic). The Raman spectra indicate that, prior to nucleation, water molecules in the vicinity of hydrophobic surfaces are more ice-like ordered than those in the bulk liquid or near either hydrophilic or partially hydrophobic surfaces. Furthermore, the degree of hydrogen-bond ordering of water observed prior to hydrate nucleation, as measured by the ratio of the inter- and intramolecular Raman OH bands, was found to have an inverse relationship with the mean induction time for hydrate formation. Following hydration formation, no significant difference in the water molecule structure was observed in the hydrate phase based on their Raman OH bands, irrespective of surface hydrophobicity. These observations made with Raman spectroscopy provide the foundations for a quantitative link between hydrate nucleation promotion and water-ordering near solid surfaces, which could enable direct comparisons with results from corresponding molecular dynamics simulations. PMID:26731126

  5. Spectroscopic Raman characterization of rutherfordine: a combined DFT and experimental study.

    Science.gov (United States)

    Bonales, L J; Colmenero, F; Cobos, J; Timón, V

    2016-06-28

    A rutherfordine mineral was studied by means of Raman spectroscopy combined with first principle calculations based on the density functional theory (DFT) method. The pseudopotential of a uranium atom was generated and its performance was evaluated for a series of uranium-containing minerals. The structure of rutherfordine was determined for two symmetries (Pmmn and Imm2) and the resulting lattice parameters, bond lengths, bond angles, and X-ray powder diffractogram were found to be in very good agreement with experimental values. The Raman spectrum was experimentally determined in the range 0-1700 cm(-1) and calculated using density functional perturbation theory. The non-scaled theoretical wavenumbers also agreed with the experimental values, and therefore a detailed interpretation of the theoretical spectra allowed us to assign the Raman bands found in the experimental spectrum. PMID:27271869

  6. Raman spectroscopic studies of thin film carbon nanostructures deposited using electro deposition technique

    Science.gov (United States)

    Dayal, Saurabh; Sasi, Arshali; Jhariya, Sapna; Sasikumar, C.

    2016-05-01

    In the present work our focus is to synthesize carbon nanostructures (CNS) by electro deposition technique without using any surface pretreatment or catalyst preparation before CNS formation. The process were carried out at significantly low voltage and at low temperature as reported elsewhere. Further the samples were characterized using different characterization tools such as SEM and Raman spectroscopy. The SEM results showed the fibres or tubular like morphology. Raman spectra shows strong finger print at 1600 cm-1 (G peak), 1350 cm-1 (D peak) along with the radial breathing mode (RBM) between 150cm-1 to 300 cm-1. This confirms the formation of tubular carbon nanostructures.

  7. Vibrational Raman spectroscopic study of scytonemin, the UV-protective cyanobacterial pigment

    Science.gov (United States)

    Edwards, H. G. M.; Garcia-Pichel, F.; Newton, E. M.; Wynn-Williams, D. D.

    2000-01-01

    The Raman spectrum of the photoprotective pigment scytonemin found in cyanobacterial sheaths has been obtained for the first time. Its skeletal structure is extensively conjugated and unique in nature. Detailed molecular vibrational assignments are proposed and a distinctive group of four corroborative vibrational bands have been identified as unique indicators for the compound. These bands, especially a prominent feature at wavenumber 1590 cm -1, are sufficiently conspicuous to be detectable in the mixed biomolecular pools of undisturbed natural microbial communities. This has been confirmed by demonstrating the Raman spectral bands for scytonemin in a sample of an intact intertidal cyanobacterial mat.

  8. Raman spectroscopic evaluation of meat batter structural changes induced by thermal treatment and salt addition.

    Science.gov (United States)

    Herrero, A M; Carmona, P; López-López, I; Jiménez-Colmenero, F

    2008-08-27

    Raman spectroscopy, texture, proximate composition, and water binding analysis were carried out to evaluate the effect of thermal treatment and/or salt addition to meat batter. For this purpose, different meat batters were elaborated: control meat batter (no salt) and meat batters with low (1.0%) and high (2.5%) NaCl content with and without thermal treatment (70 degrees C/30 min). Increase (P batter. Raman spectroscopy analysis revealed a significant (P batter. In this way, a significant correlation was found between beta-sheets, salt content, hardness, and chewiness in heated samples.

  9. Microorganism Response to Stressed Terrestrial Environments: A Raman Spectroscopic Perspective of Extremophilic Life Strategies

    Directory of Open Access Journals (Sweden)

    Howell G.M. Edwards

    2013-03-01

    Full Text Available Raman spectroscopy is a valuable analytical technique for the identification of biomolecules and minerals in natural samples, which involves little or minimal sample manipulation. In this paper, we evaluate the advantages and disadvantages of this technique applied to the study of extremophiles. Furthermore, we provide a review of the results published, up to the present point in time, of the bio- and geo-strategies adopted by different types of extremophile colonies of microorganisms. We also show the characteristic Raman signatures for the identification of pigments and minerals, which appear in those complex samples.

  10. Raman Spectroscopic Study of the Vapour Phase of 1-Methylimidazolium Ethanoate, a Protic Ionic Liquid

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Canongia Lopes, Jose N.; Ferreira, Rui;

    2010-01-01

    The gas phase over the ionic liquid 1-methylimidazolium ethanoate, [Hmim][O2CCH3], was studied by means of Raman spectroscopy. Raman spectra are presented, the species in the gas phase are identified, and their bands are assigned. The results are interpreted using ab initio quantum mechanical cal...... calculations that also predict vibrational spectra. The obtained data reinforce a previous interpretation, based on FT-ICR mass spectrometric data, that the vapor phase over [Hmim][O2CCH3] consists predominantly of two neutral molecules, monomeric ethanoic acid and 1-methylimidazole....

  11. Raman scattering in Si/SiGe nanostructures: Revealing chemical composition, strain, intermixing, and heat dissipation

    Energy Technology Data Exchange (ETDEWEB)

    Mala, S. A.; Tsybeskov, L., E-mail: tsybesko@njit.edu [Department of Electrical and Computer Engineering, New Jersey Institute of Technology, Newark, New Jersey 07102 (United States); Lockwood, D. J.; Wu, X.; Baribeau, J.-M. [National Research Council, Ottawa, Ontario K1A 0R6 (Canada)

    2014-07-07

    We present a quantitative analysis of Raman scattering in various Si/Si{sub 1-x}Ge{sub x} multilayered nanostructures with well-defined Ge composition (x) and layer thicknesses. Using Raman and transmission electron microscopy data, we discuss and model Si/SiGe intermixing and strain. By analyzing Stokes and anti-Stokes Raman signals, we calculate temperature and discuss heat dissipation in the samples under intense laser illumination.

  12. Alkali metal salts of rutin - Synthesis, spectroscopic (FT-IR, FT-Raman, UV-VIS), antioxidant and antimicrobial studies.

    Science.gov (United States)

    Samsonowicz, M; Kamińska, I; Kalinowska, M; Lewandowski, W

    2015-12-01

    In this work several metal salts of rutin with lithium, sodium, potassium, rubidium and cesium were synthesized. Their molecular structures were discussed on the basis of spectroscopic (FT-IR, FT-Raman, UV-VIS) studies. Optimized geometrical structure of rutin was calculated by B3LYP/6-311++G(∗∗) method and sodium salt of rutin were calculated by B3LYP/LanL2DZ method. Metal chelation change the biological properties of ligand therefore the antioxidant (FRAP and DPPH) and antimicrobial activities (toward Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Proteus vulgaris, Pseudomonas aeruginosa, Klebsiella pneumonia, Candida albicans and Saccharomyces cerevisiae) of alkali metal salts were evaluated and compared with the biological properties of rutin. PMID:26184478

  13. Structure, spectra and antioxidant action of ascorbic acid studied by density functional theory, Raman spectroscopic and nuclear magnetic resonance techniques.

    Science.gov (United States)

    Singh, Gurpreet; Mohanty, B P; Saini, G S S

    2016-02-15

    Structure, vibrational and nuclear magnetic resonance spectra, and antioxidant action of ascorbic acid towards hydroxyl radicals have been studied computationally and in vitro by ultraviolet-visible, nuclear magnetic resonance and vibrational spectroscopic techniques. Time dependant density functional theory calculations have been employed to specify various electronic transitions in ultraviolet-visible spectra. Observed chemical shifts and vibrational bands in nuclear magnetic resonance and vibrational spectra, respectively have been assigned with the help of calculations. Changes in the structure of ascorbic acid in aqueous phase have been examined computationally and experimentally by recording Raman spectra in aqueous medium. Theoretical calculations of the interaction between ascorbic acid molecule and hydroxyl radical predicted the formation of dehydroascorbic acid as first product, which has been confirmed by comparing its simulated spectra with the corresponding spectra of ascorbic acid in presence of hydrogen peroxide.

  14. Raman spectroscopic investigation of spinal cord injury in a rat model

    Science.gov (United States)

    Saxena, Tarun; Deng, Bin; Stelzner, Dennis; Hasenwinkel, Julie; Chaiken, Joseph

    2011-02-01

    Raman spectroscopy was used to study temporal molecular changes associated with spinal cord injury (SCI) in a rat model. Raman spectra of saline-perfused, injured, and healthy rat spinal cords were obtained and compared. Two injury models, a lateral hemisection and a moderate contusion were investigated. The net fluorescence and the Raman spectra showed clear differences between the injured and healthy spinal cords. Based on extensive histological and biochemical characterization of SCI available in the literature, these differences were hypothesized to be due to cell death, demyelination, and changes in the extracellular matrix composition, such as increased expression of proteoglycans and hyaluronic acid, at the site of injury where the glial scar forms. Further, analysis of difference spectra indicated the presence of carbonyl containing compounds, hypothesized to be products of lipid peroxidation and acid catalyzed hydrolysis of glycosaminoglycan moieties. These results compared well with in vitro experiments conducted on chondroitin sulfate sugars. Since the glial scar is thought to be a potent biochemical barrier to nerve regeneration, this observation suggests the possibility of using near infrared Raman spectroscopy to study injury progression and explore potential treatments ex vivo, and ultimately monitor potential remedial treatments within the spinal cord in vivo.

  15. Removal of Aqueous Boron by Using Complexation of Boric Acid with Polyols: A Raman Spectroscopic Study

    Energy Technology Data Exchange (ETDEWEB)

    Eom, Ki Heon; Jeong, Hui Cheol; An, Hye Young; Lim, Jun-Heok; Lee, Jea-Keun; Won, Yong Sun [Pukyong National University, Busan (Korea, Republic of)

    2015-12-15

    Boron is difficult to be removed from seawater by simple RO (reverse osmosis) membrane process, because the size of boric acid (B(OH){sub 3}), the major form of aqueous boron, is as small as the nominal pore size of RO membrane. Thus, the complexation of boric acid with polyols was suggested as an alternative way to increase the size of aqueous boron compounds and the complexation behavior was investigated with Raman spectroscopy. As a reference, the Raman peak for symmetric B-O stretching vibrational mode both in boric acid and borate ion (B(OH){sub 4}{sup -}) was selected. A Raman peak shift (877 cm{sup -1} →730 cm{sup -1}) was observed to confirm that boric acid in water is converted to borate ion as the pH increases, which is also correctly predicted by frequency calculation. Meanwhile, the Raman peak of borate ion (730 cm{sup -1}) did not appear as the pH increased when polyols were applied into aqueous solution of boric acid, suggesting that the boric acid forms complexing compounds by combining with polyols.

  16. FT-Raman, FT-IR spectroscopic and DFT studies of hexaphenoxycyclotriphosphazene

    Science.gov (United States)

    Furer, V. L.; Vandyukov, A. E.; Padie, C.; Majoral, J. P.; Caminade, A. M.; Kovalenko, V. I.

    2016-07-01

    The FTIR and FT Raman measurements of zero Gc0‧ -H and first Gc1‧ -H generations of phosphorus dendrimer built from cyclotriphosphazene core with phenoxy and deuterophenoxy terminal groups have been performed. In order to evaluate how much the frequencies, shift when changing the electronics of the system the FTIR and FT Raman spectra of phosphorus‒containing dendron with five terminal oxybenzaldehyde and one ester function Gci‧ have been also studied. Structural optimization and normal mode analysis were obtained for Gc0‧ -H and Gc0‧ -D by the density functional theory (DFT). It is discovered that dendrimer molecule exists in a stable conformation with six phenoxy terminal groups spaced above and below the flat cyclotriphosphazene core. Optimized geometric bond length and angles obtained by DFT show good agreement with a previously-published X-ray study. The phenoxy terminal groups are characterized by the well-defined line at 993 cm-1 in the experimental Raman spectrum of Gc0‧ -H and by line at 960 cm-1 in the Raman spectrum of Gc0‧ -D. Relying on DFT calculations a complete vibrational assignment is proposed for the studied dendrimers. The frequencies and relative intensity of the bands at 1589, 1487 cm-1 in the IR spectra show marked difference in dependence of the substituents on the aromatic ring.

  17. Raman spectroscopic investigations on the interactions of gastric cancer cells with 5-fluorouracil

    Institute of Scientific and Technical Information of China (English)

    Jianyu Guo; Weiying Cai; Jipeng Yang; Zhenrong Sun

    2008-01-01

    To study the efficacy and side effects of antitumor drug by the method of Raman spectroscopy, the cancerous (SGC-7901) and normal (GES-1) gastric cells were treated with 0, 25-, 100-, and 200-mg/L 5-fluorouracil (5-Fu) for 24 h, respectively, then Raman spectra of cells were recorded. The excitation wavelength was 514.5 nm and the Raman spectra in the region of 500 - 1800 cm-1 were recorded. For the gastric cancer cells, as the concentration of 5-Fu increases, the band at 1094 cm-1 attributed to the symmetric stretching vibration mode of PO2- in the DNA backbone gradually decreases, and the intensity ratio of the band at 1315 cm-1 to that at 1340 cm-1 (I1315/I1340) shows the ascending trend, and the ratio of the band area at 1655 cm-1 to that at 1450 cm-1 (A1655/A1450) shows the slight ascending trend. For the normal gastric cells, these peaks also appear changes, however, the changes are weaker than those for the cancer cells. In SGC-7901 cells, 5-Fu can interfere with the DNA synthesis and result in the reduction of the DNA content. Besides, it can affect the unsaturation degree of the hydrocarbon chains and alter the external environment of guanine and adenine residues in cancer cells. The changes of Raman spectra for normal gastric cells reveal the side effect of 5-Fu.

  18. A micro-Raman spectroscopic investigation of leukemic U-937 cells in aged cultures

    Science.gov (United States)

    Fazio, Enza; Trusso, Sebastiano; Franco, Domenico; Nicolò, Marco Sebastiano; Allegra, Alessandro; Neri, Fortunato; Musolino, Caterina; Guglielmino, Salvatore P. P.

    2016-04-01

    Recently it has been shown that micro-Raman spectroscopy combined with multivariate analysis is able to discriminate among different types of tissues and tumoral cells by the detection of significant alterations and/or reorganizations of complex biological molecules, such as nucleic acids, lipids and proteins. Moreover, its use, being in principle a non-invasive technique, appears an interesting clinical tool for the evaluation of the therapeutical effects and of the disease progression. In this work we analyzed molecular changes in aged cultures of leukemia model U937 cells with respect to fresh cultures of the same cell line. In fact, structural variations of individual neoplastic cells on aging may lead to a heterogeneous data set, therefore falsifying confidence intervals, increasing error levels of analysis and consequently limiting the use of Raman spectroscopy analysis. We found that the observed morphological changes of U937 cells corresponded to well defined modifications of the Raman contributions in selected spectral regions, where markers of specific functional groups, useful to characterize the cell state, are present. A detailed subcellular analysis showed a change in cellular organization as a function of time, and correlated to a significant increase of apoptosis levels. Besides the aforementioned study, Raman spectra were used as input for principal component analysis (PCA) in order to detect and classify spectral changes among U937 cells.

  19. The spectroscopic (FT-IR, FT-Raman, dispersive Raman and NMR) study of ethyl-6-chloronicotinate molecule by combined density functional theory

    Science.gov (United States)

    Karabacak, Mehmet; Calisir, Zuhre; Kurt, Mustafa; Kose, Etem; Atac, Ahmet

    2016-01-01

    In this study, ethyl-6-chloronicotinate (E-6-ClN) molecule is recorded in the region 4000-400 cm- 1 and 3500-100 cm- 1 (FT-IR, FT-Raman and dispersive Raman, respectively) in the solid phase. 1H and 13C nuclear magnetic resonance (NMR) spectra are recorded in DMSO solution. The structural and spectroscopic data of the molecule are obtained for two possible isomers (S1 and S2) from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule is fully optimized, vibrational spectra are calculated and fundamental vibrations are assigned on the basis of the potential energy distribution (PED) of the vibrational modes. 1H and 13C NMR chemical shifts are calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strengths, wavelengths, HOMO and LUMO energies, are performed by time-dependent density functional theory (TD-DFT). Total and partial density of state and overlap population density of state diagrams analysis are presented for E-6-ClN molecule. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential, and thermodynamic features are performed. In addition to these, reduced density gradient of the molecule is performed and discussed. As a conclusion, the calculated results are compared with the experimental spectra of the title compound. The results of the calculations are applied to simulate the vibrational spectra of the molecule, which show excellent agreement with the observed ones. The theoretical and tentative results will give us a detailed description of the structural and physicochemical properties of the molecule. Natural bond orbital analysis is done to have more information stability of the molecule arising from charge delocalization, and to reveal the information regarding charge transfer within the molecules.

  20. Behavior of H(sub2)O and OH in lawsonite : a single crystal neutron diffraction and Raman spectroscopic investigation.

    Energy Technology Data Exchange (ETDEWEB)

    Kolesov, B. A.; Lager, G. A.; Schultz, A. J.; Russian Academy of Science; Univ. of Louisville

    2008-01-01

    Neutron diffraction and polarized single-crystal Raman spectroscopic measurements were made on the high-pressure silicate lawsonite, CaAl{sub 2}(Si{sub 2}O{sub 7})(OH){sub 2} {center_dot} H{sub 2}O, from Tiburon Peninsula, California. For the diffraction measurements, intensity reflection data were collected at temperatures of 295, 110 and 20 K using time-of-flight neutron diffraction methods to further examine two reversible, order-disorder type phase transitions occurring at 273 and 155 K [Cmcm (> 273 K) {yields} Pmcn (< 273 K) {yields} P2{sub 1}cn (< 155 K)]. These data are also used to model the H atom displacements in lawsonite as a function of temperature and to provide better insight into the nature of H bonding. The Raman spectroscopic measurements (2500 to 4000 cm{sup -1} at 4 {ge} T {ge} 300 K) were carried out on the same crystal used for the neutron diffraction study. Four OH-related bands are observed between 2700 and 3600 cm{sup -1}. The OH groups and H{sub 2}O molecules, which are linked by hydrogen bonding, build quasi one-dimensional chains in lawsonite, that run parallel to [001] and thus a model consisting of isolated oscillators cannot be used to interpret the spectra at ambient temperature. A notable feature of spectral behavior at 240-260 K in the vicinity of the Cmcm {leftrightarrow} Pmcn phase transition is the change-over of strong hydrogen bonding from the OH group to the H{sub 2}O molecule. The lowest-wavenumber OH(H{sub 2}O) band at 2780 cm{sup -1} at 4 K is broad and asymmetric, which is related to strong hydrogen bonding, and is characterized by strong anharmonicity. This band was deconvoluted into a number of combination modes consisting of an internal-H{sub 2}O and various external-H{sub 2}O vibrations.

  1. Inferential monitoring of chlorinated solvents through Raman spectroscopic observation of the vibrational modes of water.

    Science.gov (United States)

    Sinfield, Joseph V; Monwuba, Chike

    2016-02-01

    Recent improvements in diode laser, fiber optic, and data acquisition technology have rejuvenated interest in field applications of Raman spectroscopy in a wide range of settings. One such application involves the observation of chlorinated solvents to facilitate the practice of "monitored natural attenuation." In this context, this manuscript focuses on means to improve the sensitivity of in-situ Raman analysis of chlorinated solvents. In particular, the work explores the performance limits of a Time-Resolved Raman Spectroscopy (TRRS) system employed to observe chlorinated solvents in aqueous samples via laboratory tests conducted on both liquid standards of trichloroethylene (TCE) and simulated biodegraded field samples. Quantitative assessment of TCE in solution is carried out through both direct observation of TCE Raman functional groups (381 cm(-1) (δ skeletal), 840 cm(-1) (νCCl) and 1242 cm(-1) (δCH)) and indirect observation of the broad OH stretching (2700-3800 cm(-1)) Raman modes of water. Results from tests on simple solutions show that the TRRS system can detect TCE at aqueous concentrations as low as 70 ppm by directly monitoring the 381 cm(-1) TCE line, whereas observation of the OH stretching line of water (3393 cm(-1)) provides an indirect indication of TCE presence with nearly a 9× improvement in detection level. This unique and counterintuitive mechanism to detect the presence of chlorinated compounds in solution takes advantage of the influence of chlorine on the vibrational modes of water. This influence, which is believed to be attributed to the formation of hydrogen bonds and their resultant interactions with the solvation shell, may serve as a more sensitive and robust indication of the presence of aggregate chlorinated solvent contamination in aqueous systems. Tests performed on simulated biodegraded field samples demonstrate that the indirect detection mechanism is apparent even in complex samples representative of typical field

  2. Resonance Raman Spectroscopic and Theoretical Study of Geometry Distortion of Thiourea in 21A State

    Institute of Scientific and Technical Information of China (English)

    Hai-bo Zhang; Yan-ying Zhao; Xu-ming Zheng

    2012-01-01

    The A-band resonance Raman spectra of thiourea were obtained in water and acetonitrile solution.B3LYP/6-311++G(3df,3pd) and RCIS/6-311++G(3df,3pd) calculations were done to elucidate the ultraviolet electronic transitions,the distorted geometry structure and the saddle point of thiourea in 21A excited state,respectively.The resonance Raman spectra were assigned.The absorption spectrum and resonance Raman intensities were modeled using Heller's time-dependent wavepacket approach to resonance Raman scattering.The results indicate that largest change in the displacement takes place with the C=S stretch mode v6 (|Δ|=0.95) and noticeable changes appear in the HsN3H6+H8N4H7 wag v5 (|Δ|=0.19),NCN symmetric stretch+C=S stretch+N3H6+H8N4 wag v4 (|Δ|=0.18),while the moderate intensities of 2v15 and 4v15 are mostly due to the large excited state frequency changes of v15,but not due to its significant change in the normal mode displacement.The mechanism of the appearance of even overtones of the S=CN2 out of plane deformation is explored.The results indicate that a Franck-Condon region saddle point is the driving force for the quadric phonon mechanism within the standard A-term of resonance Raman scattering,which leads to the pyramidalization of the carbon center and the geometry distortion of thiourea molecule in 21A excited state.

  3. Ellipsometric and Raman spectroscopic study of nanocrystalline silicon thin films prepared by a rf magnetron sputtering technique

    International Nuclear Information System (INIS)

    The structure of nanocrystalline silicon thin films (nc-Si:H) deposited by rf magnetron sputtering of a high-purity crystalline silicon target using argon (30%) and hydrogen (70%) gas mixture, under different pressures (P = 2, 3 and 4 Pa) and different substrate temperature (Ts = 100, 150 and 200 deg. C), has been studied with spectroscopic ellipsometry (SE; 1.5-5 eV) complemented with Raman spectroscopy measurements. The ellipsometry data were carefully analyzed using the Brueggeman effective medium approximation and the Tauc-Lorentz model. The results of this investigation clearly show that the samples deposited at 2 Pa present a completely amorphous structure whatever the substrate temperature, while those deposited at 3 and 4 Pa exhibit a nanocrystalline structure. These results suggest the existence of a threshold pressure around 3 Pa for which crystallization occurs. The samples are well crystallized with a crystalline volume fraction ranging from about 60 to 90%, and exhibit a mixture of small and large crystallite sizes. The deposition temperature has practically no effect on the size of the crystallites and on the average crystalline volume fractions. These results are in good agreement with the Raman spectroscopy data, and suggest the formation of Si crystallites in the gas phase. The analysis of the ellipsometric spectra also shows that the bulk layer is initiated from an amorphous interface (a-Si:H) present in the first steps of the growth, and is followed by a less crystallized subsurface layer.

  4. Ellipsometric and Raman spectroscopic study of nanocrystalline silicon thin films prepared by a rf magnetron sputtering technique

    Science.gov (United States)

    Bouizem, Y.; Abbes, C.; Sib, J. D.; Benlakehal, D.; Baghdad, R.; Chahed, L.; Zellama, K.; Charvet, S.

    2008-11-01

    The structure of nanocrystalline silicon thin films (nc-Si:H) deposited by rf magnetron sputtering of a high-purity crystalline silicon target using argon (30%) and hydrogen (70%) gas mixture, under different pressures (P = 2, 3 and 4 Pa) and different substrate temperature (Ts = 100, 150 and 200 °C), has been studied with spectroscopic ellipsometry (SE; 1.5-5 eV) complemented with Raman spectroscopy measurements. The ellipsometry data were carefully analyzed using the Brüggeman effective medium approximation and the Tauc-Lorentz model. The results of this investigation clearly show that the samples deposited at 2 Pa present a completely amorphous structure whatever the substrate temperature, while those deposited at 3 and 4 Pa exhibit a nanocrystalline structure. These results suggest the existence of a threshold pressure around 3 Pa for which crystallization occurs. The samples are well crystallized with a crystalline volume fraction ranging from about 60 to 90%, and exhibit a mixture of small and large crystallite sizes. The deposition temperature has practically no effect on the size of the crystallites and on the average crystalline volume fractions. These results are in good agreement with the Raman spectroscopy data, and suggest the formation of Si crystallites in the gas phase. The analysis of the ellipsometric spectra also shows that the bulk layer is initiated from an amorphous interface (a-Si:H) present in the first steps of the growth, and is followed by a less crystallized subsurface layer.

  5. A new combined nuclear magnetic resonance and Raman spectroscopic probe applied to in situ investigations of catalysts and catalytic processes

    Energy Technology Data Exchange (ETDEWEB)

    Camp, Jules C. J.; Mantle, Michael D. [Department of Chemical Engineering and Biotechnology, University of Cambridge, Pembroke Street, Cambridge CB2 3RA (United Kingdom); York, Andrew P. E. [Johnson Matthey Technology Centre, Blounts Court, Sonning Common, Reading RG4 9NH (United Kingdom); McGregor, James, E-mail: james.mcgregor@sheffield.ac.uk [Department of Chemical and Biological Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom)

    2014-06-15

    Both Raman and nuclear magnetic resonance (NMR) spectroscopies are valuable analytical techniques capable of providing mechanistic information and thereby providing insights into chemical processes, including catalytic reactions. Since both techniques are chemically sensitive, they yield not only structural information but also quantitative analysis. In this work, for the first time, the combination of the two techniques in a single experimental apparatus is reported. This entailed the design of a new experimental probe capable of recording simultaneous measurements on the same sample and/or system of interest. The individual datasets acquired by each spectroscopic method are compared to their unmodified, stand-alone equivalents on a single sample as a means to benchmark this novel piece of equipment. The application towards monitoring reaction progress is demonstrated through the evolution of the homogeneous catalysed metathesis of 1‑hexene, with both experimental techniques able to detect reactant consumption and product evolution. This is extended by inclusion of magic angle spinning (MAS) NMR capabilities with a custom made MAS 7 mm rotor capable of spinning speeds up to 1600 Hz, quantified by analysis of the spinning sidebands of a sample of KBr. The value of this is demonstrated through an application involving heterogeneous catalysis, namely the metathesis of 2-pentene and ethene. This provides the added benefit of being able to monitor both the reaction progress (by NMR spectroscopy) and also the structure of the catalyst (by Raman spectroscopy) on the very same sample, facilitating the development of structure-performance relationships.

  6. Exfoliation and Raman Spectroscopic Fingerprint of Few-Layer NiPS3 Van der Waals Crystals

    Science.gov (United States)

    Kuo, Cheng-Tai; Neumann, Michael; Balamurugan, Karuppannan; Park, Hyun Ju; Kang, Soonmin; Shiu, Hung Wei; Kang, Jin Hyoun; Hong, Byung Hee; Han, Moonsup; Noh, Tae Won; Park, Je-Geun

    2016-02-01

    The range of mechanically cleavable Van der Waals crystals covers materials with diverse physical and chemical properties. However, very few of these materials exhibit magnetism or magnetic order, and thus the provision of cleavable magnetic compounds would supply invaluable building blocks for the design of heterostructures assembled from Van der Waals crystals. Here we report the first successful isolation of monolayer and few-layer samples of the compound nickel phosphorus trisulfide (NiPS3) by mechanical exfoliation. This material belongs to the class of transition metal phosphorus trisulfides (MPS3), several of which exhibit antiferromagnetic order at low temperature, and which have not been reported in the form of ultrathin sheets so far. We establish layer numbers by optical bright field microscopy and atomic force microscopy, and perform a detailed Raman spectroscopic characterization of bilayer and thicker NiPS3 flakes. Raman spectral features are strong functions of excitation wavelength and sample thickness, highlighting the important role of interlayer coupling. Furthermore, our observations provide a spectral fingerprint for distinct layer numbers, allowing us to establish a sensitive and convenient means for layer number determination.

  7. Thermal stability and hot-stage Raman spectroscopic study of Ca-montmorillonite modified with different surfactants: A comparative study

    International Nuclear Information System (INIS)

    Highlights: • A typical Ca-montmorillonite was modified with three surfactants through ion exchange. • The organoclays were characterized by XRD, TG and hot stage Raman. • The structural geometry and thermal properties of organoclays were analyzed. • The prepared organoclays show potential prospects in the environmental remediation. - Abstract: Three long chain cationic surfactants were intercalated into Ca-montmorillonite through ion exchange and the obtained organoclays were characterized by X-ray diffraction (XRD), high resolution thermogravimetric analysis (TG) and Raman spectroscopy. The intercalation of surfactants not only changes the surface properties of clay from hydrophilic to hydrophobic but also greatly increases the basal spacing of the interlayers based on XRD analysis. The thermal stability of organoclays intercalated with three surfactants (TTAB, DTAB and CTAB) and the different arrangements of the surfactant molecules intercalated into Ca-montmorillonite were determined by TG-DTG analysis. A Raman spectroscopic study on the Ca-montmorillonite modified by three surfactants prepared at different concentrations provided the detailed conformational ordering of different intercalated long-chain surfactants under different conditions. The wavenumber of the antisymmetric stretching mode is more sensitive than that of the symmetric stretching mode to the mobility of the tail of the amine chain. At room temperature, the conformational ordering is more easily affected by the packing density in the lateral model. With the increase of the temperature, the positions of both the antisymmetric and symmetric stretching bands shift to higher wavenumbers, which indicates a decrease of conformational ordering. This study offers new insights into the structure and properties of Ca-montmorillonite modified with different long chain surfactants. Moreover, the experimental results confirm the potential applications of organic Ca-montmorillonites for the removal

  8. Raman spectroscopic evidence for colinear arrangement in the solid state of thermochromic distibanes

    Science.gov (United States)

    Bürger, H.; Eujen, R.; Becker, G.; Mundt, O.; Westerhausen, M.; Witthauer, C.

    1983-04-01

    The IR and Raman spectra of the compounds (CH 3) 2SbSb(CH 3) 2 (I), [(CH 3) 3Si] 2SbSb[Si(CH 3) 3] 2 (II), [(CH 3) 3Si] 2AsAs[Si(CH 3) 3] 2 (III) and (C 6H 5) 2SbSb(C 6H 5) 2 (IV) have been studied in the liquid and solid states. Given assignments for I to III are based on normal coordinate analyses, and force constants are reported. The solid state Raman spectra of I and II exhibit strong lines near 50 cm -1, which are assigned to the longitudinal acoustic mode of an infinite linear chain of Sb atoms. Intermolecular Sb…Sb force constants, 0.125 and 0.18 N cm -1, are determined for I and II respectively.

  9. High pressure Raman spectroscopic studies of (p−chloroanilinium){sub 2}CuCl{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Ghalsasi, Pallavi [School of Engineering and Technology, Navrachana University, Vadodara- 391 410 (India); Garg, Nandini; Sharma, S. M. [High Pressure and Synchrotron Radiation Physics Division, Bhabha Atomic Research Center, Mumbai-400 085 (India); Ghalsasi, Prasanna, E-mail: prasanna.ghalsasi@gmail.com; Mande, Hemant, E-mail: prasanna.ghalsasi@gmail.com [Department of Chemistry, The Maharaja Sayajirao Gaikawad University of Baroda, Vadodara - 390 001, Gujarat (India)

    2014-04-24

    (p−chloroanilinium){sub 2}CuCl{sub 4} has a corner shared layered structure of CuCl6{sup 4−} octahedra with p-chloroanilinium cation sandwiched between the layers. The CuCl{sub 6} octahedra are irregular due to Jahn-Teller distortion. We report our high pressure Raman results on this compound in the present manuscript. Our results indicate significant changes in Raman spectra at ∼ 3 GPa and ∼ 8 GPa. The changes at 3 GPa can be attributed to a reduction in puckering of the CuCl{sub 4}{sup 2−} layer and the transition at 8 GPa, which also leads to a colour change of this sample to deep red, could be due to delocalization of the eg electrons along with a reduction of the cooperative Jahn-Teller distortion in this layer. These changes were found to be reversible.

  10. Polychloride monoanions from [Cl3]- to [Cl9]- : a Raman spectroscopic and quantum chemical investigation.

    Science.gov (United States)

    Brückner, Robin; Haller, Heike; Ellwanger, Mathias; Riedel, Sebastian

    2012-04-27

    Polychloride monoanions stabilized by quaternary ammonium salts are investigated using Raman spectroscopy and state-of-the-art quantum-chemical calculations. A regular V-shaped pentachloride is characterized for the [N(Me)(4)][Cl(5)] salt, whereas a hockey-stick-like structure is tentatively assigned for [N(Et)(4)][Cl(2)⋅⋅⋅Cl(3)(-)]. Increasing the size of the cation to the quaternary ammonium salts [NPr(4)](+) and [NBu(4)](+) leads to the formation of the [Cl(3)](-) anion. The latter is found to be a pale yellow liquid at about 40 °C, whereas all the other compounds exist as powders. Further to these observations, the novel [Cl(9)](-) anion is characterized by low-temperature Raman spectroscopy in conjunction with quantum-chemical calculations. PMID:22461376

  11. Biomarkers and their Raman spectroscopic signatures: a spectral challenge for analytical astrobiology.

    Science.gov (United States)

    Edwards, Howell G M; Hutchinson, Ian B; Ingley, Richard; Jehlička, Jan

    2014-12-13

    The remote robotic exploration of extraterrestrial scenarios for evidence of biological colonization in 'search for life' missions using Raman spectroscopy is critically dependent on two major factors: firstly, the Raman spectral recognition of characteristic biochemical spectral signatures in the presence of mineral matrix features; and secondly, the positive unambiguous identification of molecular biomaterials which are indicative of extinct or extant life. Both of these factors are considered here: the most important criterion is the clear definition of which biochemicals truly represent biomarkers, whose presence in the planetary geological record from an analytical astrobiological standpoint will unambiguously be indicative of life as recognized from its remote instrumental interrogation. Also discussed in this paper are chemical compounds which are associated with living systems, including biominerals, which may not in themselves be definitive signatures of life processes and origins but whose presence provides an indicator of potential life-bearing matrices. PMID:25368349

  12. Temperature dependent Raman spectroscopic study of mono-, bi-, and tri-layer molybdenum ditelluride

    Science.gov (United States)

    Park, June; Kim, Younghee; Jhon, Young In; Jhon, Young Min

    2015-10-01

    We investigate the thermal properties of mono-, bi- and tri-layer MoTe2 by using temperature-dependent Raman spectroscopy ranging from 90 K to 300 K. The E2g 1 and B2g 1 modes of MoTe2 blueshift as the temperature decreases. The temperature dependence of the peak positions obtained from mono- to tri-layer MoTe2 is analyzed using the Grüneisen model. The first order temperature coefficients of E2g 1 and B2g 1 Raman modes of mono- to tri-layer MoTe2 are extracted. This study provides the fundamental information about the thermal properties of MoTe2 layers, which is crucial for developing thermal and electronic applications of MoTe2 based devices.

  13. Anti-Stokes emissions and determination of Stark sub-level diagram of Er{sup 3+} ions in KY{sub 3}F{sub 10}

    Energy Technology Data Exchange (ETDEWEB)

    Boulma, E [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Diaf, M [Departement de Physique, Universite Badji Mokhtar Annaba, BP12, 23000 Annaba, Algerie (Germany); Jouart, J P [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Bouffard, M [Laboratoire d' Energetique et d' Optique, UTAP, Universite de Reims Champagne-Ardenne, BP 1039, Reims Cedex 51 687 (France); Doualan, J L [Centre Interdisciplinaire de Recherches Ions Lasers (CIRIL), UMR 6637 CNRS-CEA-ISMRA, ENSI de Caen, 6 Boulevard Marechal Juin, 14050 Caen Cedex (France); Moncorge, R [Centre Interdisciplinaire de Recherches Ions Lasers (CIRIL), UMR 6637 CNRS-CEA-ISMRA, ENSI de Caen, 6 Boulevard Marechal Juin, 14050 Caen Cedex (France)

    2006-07-26

    We are interested, in this work, in determining the Stark sub-level of Er{sup 3+} ions doping a KY{sub 3}F{sub 10} single crystal with a molar concentration of 1%. We have used a new method of measurement of energies of the ground level and emitting levels from excitation and anti-Stokes emission spectra recorded at liquid nitrogen temperature. This technique is based on a spectral analysis of the anti-Stokes emissions recorded after selective excitation with a red dye tunable laser. Thus, we could determine the Stark sub-levels of the ground and the principal emitting levels in the infrared, visible and near-UV ranges with a very good precision.

  14. Facile fabrication of dendritic silver structures and their surface enhanced Raman spectroscopic properties

    Indian Academy of Sciences (India)

    Jisheng Yang; Zhengdong Jiang

    2015-01-01

    A simple and efficient approach was developed to fabricate silver dendrites by Cu reducing Ag+ in AgNO3 solution. The growth speed, morphologies and structures of the silver dendrites strongly depend on AgNO3 concentration and reaction time. The silver dendrites were formed from nanosheets and the crystal structure is face-centered cubic. Rhodamine 6G was used as probe molecule to show that the silver dendrites have high sensitivity to surface enhanced Raman spectroscopy response.

  15. Raman spectroscopic study of DL valine under pressure up to 20 GPa

    Science.gov (United States)

    Rêgo, F. S. C.; Lima, J. A.; Freire, P. T. C.; Melo, F. E. A.; Mendes Filho, J.; Polian, A.

    2016-04-01

    DL-valine crystal was studied by Raman spectroscopy under hydrostatic pressure using a diamond anvil cell from ambient pressure up to 19.4 GPa in the spectral range from 40 to 3300 cm-1. Modifications in the spectra furnished evidence of the occurrence of two structural phase transitions undergone by this racemic amino acid crystal. The classification of the vibrational modes, the behavior of their wavenumber as a function of the pressure and the reversibility of the phase transitions are discussed.

  16. A Combined Raman Spectroscopic and Thermogravimetric Analysis Study on Oxidation of Coal with Different Ranks

    Directory of Open Access Journals (Sweden)

    Weiqing Zhang

    2015-01-01

    Full Text Available Raman spectroscopy and nonisothermal thermogravimetric analysis (TGA measurements have been reported for different rank coals (lignite, bituminous coal, and anthracite and the relationship between the measurements was examined. It was found that the Raman spectra parameters can be used to characterize structure changes in the different rank coals, such as the band area ratios based on the curve-fitted results. Higher ranked coal was found to have higher values of IGR/IAll and IG+GR/IAll but lower values of ID/I(G+GR, IDL/I(G+GR, IS+SL/I(G+GR, and I(GL+GL'/I(G+GR. The oxidation properties of the coal samples were characterized by the reactivity indexes Tig, T20%, and Tmax from TGA data which were found to correlate well with the band area ratios of IGR/IAll, IG+GR/IAll, and IS+SL/I(G+GR. Based on these correlations, the Raman band area ratios were found to correlate with the oxidation activity of coal providing additional structural information which can be used to understand the changes in the TGA measurements.

  17. Raman-spectroscopic study of lanthanide trifluorides with the {beta}-YF{sub 3} structure

    Energy Technology Data Exchange (ETDEWEB)

    Lage, M M [Departamento de Fisica, ICEx, UFMG, CP 702, 30123-970 Belo Horizonte (Brazil); Righi, A [Departamento de Fisica, ICEx, UFMG, CP 702, 30123-970 Belo Horizonte (Brazil); Matinaga, F M [Departamento de Fisica, ICEx, UFMG, CP 702, 30123-970 Belo Horizonte (Brazil); Gesland, J-Y [Universite du Maine-Cristallogenese, UMR 6087, 72085 Le Mans cedex9 (France); Moreira, R L [Departamento de Fisica, ICEx, UFMG, CP 702, 30123-970 Belo Horizonte (Brazil)

    2004-05-12

    We have performed polarized Raman scattering measurements on several Czochralski-grown lanthanide trifluoride (LnF{sub 3}) crystals presenting the {beta}-YF{sub 3} structure (space group: Pnma). The phonon mode assignments for the DyF{sub 3} and LuF{sub 3} spectra are given for the first time. Besides this, the Raman spectra of TbF{sub 3}, ErF{sub 3} and YbF{sub 3} complete and extend previous studies on these materials. The vibrational modes of LnF{sub 3} compounds are then correlated with those of the archetype {beta}-YF{sub 3} crystal. The totally symmetrical fundamentals present a strong dependence on the scattering geometry, similar to what is shown by molecular crystals with weakly interacting molecules. Most of the Raman features are well behaved with the lanthanide ion substitution. Although the observed modes always involve all ions, it was possible to discern modes that are dominated by the motion of either the lanthanide or the fluorine ions. The intensity of some low frequency modes has proved to be quite dependent on the orthorhombic distortion of the quasi-hexagonal structure.

  18. Houttuynia cordata Thunb extract induces cytotoxicity in human nasopharyngeal carcinoma cells: Raman spectroscopic studies

    Science.gov (United States)

    Chen, Weiwei; Li, Zuanfang; Yu, Yun; Lin, Duo; Huang, Hao; Shi, Hong

    2016-01-01

    The molecular mechanisms of cytotoxicity induced by Houttuynia cordata Thunb (HCT) in nasopharyngeal carcinoma (NPC) cells was investigated by Raman spectroscopy (RS). The average Raman spectra of cell groups treated with HCT (0, 62.5, 125, 250, and 500 μg ml-1) for 24 h were measured separately. Compared to the control group, the intensities of the selected bands (1002, 1338, and 1448 cm-1) related to protein, DNA, and lipid in the treatment groups decreased obviously as the concentration of HCT increased. Both cell groups treated with 250 and 500 μg ml-1 of HCT could be differentiated from the control group by principal component analysis (PCA) combined with linear discriminate analysis (LDA) with a diagnostic accuracy of 100%, suggesting that cytotoxicity occurred and that 250 μg ml-1 was the proper dose for treatment. Simultaneously, the Raman spectra of cells treated with different treatment times with 250 μg ml-1 of HCT were obtained. We can get that treatment with HCT decreased cell viability in a dose and time-dependent fashion. The results indicated that the RS combined with PCA-LDA can be used for pharmacokinetics studies of HCT in NPC cells, which could also provide useful data for clinical dosage optimization for HCT.

  19. Phase Transition in CCl4 under Pressure: a Raman Spectroscopic Study

    Institute of Scientific and Technical Information of China (English)

    LIU Tie-Cheng; ZHOU Mi; GAO Shu-Qin; LI Zuo-Wei; LI Zhan-Long; ZHANG Peng; LI Liang; LV Tian-Quan; XU Da-Peng

    2009-01-01

    High-pressure Raman studies at room temperature are performed on CCla up to 13 GPa. The Raman bands of the internal modes (v2, v4 and v1) show entirely positive pressure dependence. The slopes dw/dP of the internal modes exhibit two sudden changes at 0.73 GPa and 7.13 GPa, respectively. A new lower frequency mode (225cm-1) appears at 3.03 GPa, and the splitting of v2, v3 and v4 occurs at about 7.13 GPa. Moreover, Raman spectra of Fermi resonance show that the relative position of the v1 + v4 combination and the v3 fundamental firstly interchanges corresponding to that at ambient pressure, then the v1 + va combination disappears in the gradual process of compression. It is indicated that the pressure-induced phase transition from CCl4 II to CCl4 III occurs at 0.73 GPa, and CCl4 III undergoes a transition to CCl4 IV below 3.03 GPa. Further CCl4 IV transforms in a new high-pressure phase at about 7.13 GPa, and the symmetry of the new high-pressure phase is lower than that of CCl4 IV. All the transitions are reversible during decompression.

  20. A portable Raman acoustic levitation spectroscopic system for the identification and environmental monitoring of algal cells.

    Science.gov (United States)

    Wood, Bayden R; Heraud, Philip; Stojkovic, Slobodanka; Morrison, Danielle; Beardall, John; McNaughton, Don

    2005-08-01

    We report the coupling of a portable Raman spectrometer to an acoustic levitation device to enable environmental monitoring and the potential taxonomic identification of microalgae. Spectra of living cells were recorded at 785 nm using a fiber-optic probe coupled to a portable Raman spectrometer. The spectra exhibit an excellent signal-to-noise ratio and clearly show bands from chlorophyll a and beta-carotene. Spectra of levitated photobleached microalgae clearly show a reduction in chlorophyll a concentration relative to beta-carotene after 10 min of exposure to a quartz halogen lamp. Spectra recorded from levitated nitrogen-limited cells also show a significant reduction in bands associated with chlorophyll a, as compared to nitrogen-replete cells. To investigate the diagnostic capability of the technique, four species of microalgae were analyzed. Good quality spectra of all four species were obtained showing varying ratios of beta-carotene to chlorophyll. The combination of an acoustic levitation device and a portable Raman spectrometer shows potential as a taxonomic and environmental monitoring tool with direct application to field studies in remote environments. PMID:16053309

  1. High-pressure measuring cell for Raman spectroscopic studies of natural gas

    DEFF Research Database (Denmark)

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

    2001-01-01

    A system for obtaining Raman spectra of gases at high pressure has been constructed. In order to ensure that a natural gas sample is totally representative, a high-pressure gas-measuring cell has been developed, built up by stainless steel fittings and a sapphire tube. The design and construction...... of this cell are described. A perfect pressure seal has been demonstrated up to 15.0 MPaA (MPa absolute). The cell has been successfully used to obtain Raman spectra of natural gas samples. Some of these spectra are presented and assigned. The most remarkable observation in the spectra is that it is possible...... to detect hydrogen sulfide at concentrations of 1-3 mg H2S/Nm(3). An attempt to make a quantitative analysis of natural gas by the so-called "ratio method" is presented. In addition to this, the relative normalized differential Raman scattering cross sections for ethane and i-butane molecules at 8.0 MPa...

  2. Raman spectroscopic studies of Nd{sub 0.75}Sm{sub 0.25}GaO{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Nithya, R., E-mail: nithya@igcar.gov.in; Ravindran, T. R. [Materials Science Group, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, TN (India); Daniel, D. J. [Centre for Crystal Growth, SSN College of Engineering, Kalavakkam-603110, TN (India)

    2015-06-24

    Single crystals of Nd{sub 1-x}Sm{sub x}GaO{sub 3} (x= 0 and 0.25) were grown by a four mirror IR image furnace using floating zone technique. The crystals are characterized by X-ray diffraction and Raman spectroscopic measurements. NGO adopts orthorhombic structure with Pbnm symmetry and samarium substituted compound also exhibited the same structure as that of the pristine compound without secondary phases. Polarized Raman spectra are measured at ambient temperature in a back scattering geometry. Spectra exhibit low intensity first-order Raman bands. In addition, several high intensity second-order Raman bands have been observed in the frequency range 2000 to 4000 cm{sup −1}.

  3. Raman scattering mediated by neighboring molecules.

    Science.gov (United States)

    Williams, Mathew D; Bradshaw, David S; Andrews, David L

    2016-05-01

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process.

  4. Raman scattering mediated by neighboring molecules

    Science.gov (United States)

    Williams, Mathew D.; Bradshaw, David S.; Andrews, David L.

    2016-05-01

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process.

  5. Raman properties of GaSb nanoparticles embedded in SiO2 films

    Institute of Scientific and Technical Information of China (English)

    Liu Fa-Min; Wang Tian-Min; Zhang Li-De

    2004-01-01

    The Raman shifts of nanocrystalline GaSb excited by an Ar+ ion laser at wavelengths 514.5, 496.5, 488.0, 476.5,and 457.9nm are studied by an SPEX-1403 laser Raman spectrometer respectively, and they are explained by phonon confinement, tensile stress, resonant Raman scattering and quantum size effects. The Stokes and anti-Stokes Raman spectra of GaSb nanocrystals strongly support the Raman feature of GaSb nanocrystals. The calculated optical spectra compare well with experimental data on Raman scattering GaSb nanocrystals.

  6. Visible-IR and Raman micro-spectroscopic investigation of three Itokawa particles collected by Hayabusa

    Science.gov (United States)

    Brunetto, R.; Bonal, L.; Beck, P.; Dartois, E.; Dionnet, Z.; Djouadi, Z.; Füri, E.; Kakazu, Y.; Oudayer, P.; Quirico, E.; Engrand, C.

    2014-07-01

    HAYABUSA grains offer a unique perspective to better understand the link between asteroids and cosmomaterials available in the laboratory and to get an insight on the early stages of surface space weathering. The scientific objectives of our consortium are threefold: (i) the characterization of asteroidal surface processes (e.g., space weathering alteration); (ii) the assessment of parent-body alteration processes; (iii) the search for a possible association between S-type asteroids and micrometeorites. To this aim, our strategy is based on a combination of analytical techniques. Here we report a first series of results obtained through Visible-Infrared and Raman spectroscopy of three Itokawa particles (RA-QD02-0163, -0174, and -0213) collected by the Hayabusa spacecraft and provided by JAXA for our consortium. In a first step, our main objective was to collect maximum information without altering the particles. Reported results were thus obtained on the raw particles, both (i) in their original containers, and (ii) deposited on diamond windows. Raman and IR confocal spectra were acquired at the SMIS beamline of the French national synchrotron facility SOLEIL and at the Lyon Raman national facility using spots of 2 μ m for the Raman, and 10--20 μ m for the IR analyses. Point analyses and automatic mapping were performed. Analytical parameters (e.g., laser power on the sample) were optimized to prevent any damage. Diffuse reflectance spectra (i=45°, e=0°) in the visible and near-IR wavelengths were obtained with an IAS-CSNSM in-home system coupling a fiber spectrometer to an optical microscope, providing a 20-μ m spot on sample. In the case of particle -0163, Raman and IR results reveal a heterogeneous mixing of minerals, mostly olivine (Fo76), and Ca-rich (En50, Wo50) and Ca-poor (En85) pyroxenes. The modal distribution of these minerals is determined based on the spectral maps. The mineral compositions of -0163 are consistent with those previously reported on

  7. Raman spectroscopic study of radioresistant oral cancer sublines established by fractionated ionizing radiation.

    Directory of Open Access Journals (Sweden)

    Mohd Yasser

    Full Text Available Radiotherapy is an important treatment modality for oral cancer. However, development of radioresistance is a major hurdle in the efficacy of radiotherapy in oral cancer patients. Identifying predictors of radioresistance is a challenging task and has met with little success. The aim of the present study was to explore the differential spectral profiles of the established radioresistant sublines and parental oral cancer cell lines by Raman spectroscopy. We have established radioresistant sublines namely, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B from its parental UPCI:SCC029B cell line, by using clinically admissible 2Gy fractionated ionizing radiation (FIR. The developed radioresistant character was validated by clonogenic cell survival assay and known radioresistance-related protein markers like Mcl-1, Bcl-2, Cox-2 and Survivin. Altered cellular morphology with significant increase (p<0.001 in the number of filopodia in radioresistant cells with respect to parental cells was observed. The Raman spectra of parental UPCI:SCC029B, 50Gy-UPCI:SCC029B and 70Gy-UPCI:SCC029B cells were acquired and spectral features indicate possible differences in biomolecules like proteins, lipids and nucleic acids. Principal component analysis (PCA provided three clusters corresponding to radioresistant 50Gy, 70Gy-UPCI:SCC029B sublines and parental UPCI:SCC029B cell line with minor overlap, which suggest altered molecular profile acquired by the radioresistant cells due to multiple doses of irradiation. The findings of this study support the potential of Raman spectroscopy in prediction of radioresistance and possibly contribute to better prognosis of oral cancer.

  8. Infra-red and Raman spectroscopic studies of infected and affected dentine

    International Nuclear Information System (INIS)

    Diagnosis of infected and affected dentine is an important factor in clinical restorative treatment of dentine. In this study, the IR and Raman spectra of the sound dentine, infected dentine and affected dentine are reported. The structure of infected dentine and affected dentine has been compared with the sound dentine and hydroxyapatite. It is shown while the infected dentine has lost its structure, the affected dentine has more or less a structure similar to the sound dentine. The molecular structure of collagen remains unchanged in both infected and affected dentine

  9. RAMAN SPECTROSCOPIC STUDY ON THE CHAIN CONFORMATION OF ELECTROSYNTHESIZED POLY(p-PHENYLENE) FILMS

    Institute of Scientific and Technical Information of China (English)

    Feng-en Chen; Ming-xiao Fu; Fan Wang; Bin Fan; Gao-quan Shi

    2005-01-01

    Poly(p-phenylene) (PPP) films have been electrochemically deposited on mirrorlike stainless steel (SS) electrode surfaces by direct oxidation of benzene in boron trifluoride diethyl etherate (BFEE) solutions at a constant applied potential of 1.7 V (versus Ag/AgCl). The chain conformations of as-grown PPP films have been studied by Raman spectroscopy. The results demonstrated that high synthesis temperature favors the formation of planar PPP, and the conformation of planar PPP can be changed into torsional PPP by cooling treatment.

  10. Raman spectroscopic study on archaeological glasses in Thailand: Ancient Thai Glass

    Science.gov (United States)

    Won-in, K.; Thongkam, Y.; Pongkrapan, S.; Intarasiri, S.; Thongleurm, C.; Kamwanna, T.; Leelawathanasuk, T.; Dararutana, P.

    2011-12-01

    Glasses have been used as ornamental and decorative objects in Thailand for several hundred years as seen in archaeological artifacts, such as glass beads found throughout the regions. Decorative glasses can generally be seen as architectural components in Buddhist temples and old-styled palaces. They came in various colors ranging from transparent to amber, blue, green and red of different shades and tones. Fragments of archaeological glass samples were characterized for the first time using Raman spectrophotometer with the aim of obtaining information that would lead to the identification of the glass samples by means of laser scattering. The samples were also investigated using other techniques, such as proton induced X-ray emission spectroscopy, scanning electron microscopy cooperated with energy dispersive X-ray fluorescence spectrometer and synchrotron radiation to induced X-ray fluorescence. The results showed that they were mostly lead-silica based glasses whose colors were induced by metal ions. The differences in chemical compositions were confirmed by Raman signature spectra.

  11. Surface enhanced Raman spectroscopic studies on aspirin : An experimental and theoretical approach

    Science.gov (United States)

    Premkumar, R.; Premkumar, S.; Rekha, T. N.; Parameswari, A.; Mathavan, T.; Benial, A. Milton Franklin

    2016-05-01

    Surface enhanced Raman scattering (SERS) studies on aspirin molecule adsorbed on silver nanoparticles (AgNPs) were investigated by experimental and density functional theory approach. The AgNPs were synthesized by the solution-combustion method and characterized by the X-ray diffraction and high resolution-transmission electron microscopy techniques. The averaged particle size of synthesized AgNPs was calculated as ˜55 nm. The normal Raman spectrum (nRs) and SERS spectrum of the aspirin were recorded. The molecular structure of the aspirin and aspirin adsorbed on silver cluster were optimized by the DFT/ B3PW91 method with LanL2DZ basis set. The vibrational frequencies were calculated and assigned on the basis of potential energy distribution calculation. The calculated nRs and SERS frequencies were correlated well with the observed frequencies. The flat-on orientation was predicted from the nRs and SERS spectra, when the aspirin adsorbed on the AgNPs. Hence, the present studies lead to the understanding of adsorption process of aspirin on the AgNPs, which paves the way for biomedical applications.

  12. A RAMAN-SPECTROSCOPIC STUDY OF PHASE STRUCTURE OF DRAWN POLYETHYLENE

    Institute of Scientific and Technical Information of China (English)

    YAN Rongjiang; JIANG Bingzheng

    1993-01-01

    A drawn high density polyethylene(HDPE) has been measured by Raman spectroscopy and differential scanning calorimetry (DSC). The crystalline structure of drawn HDPE is analysed by the Raman internal modes in terms of mass fractions of the crystalline orthorhombic phase, the liquid- like amorphous phase and the disordered anisotropic phase. The mass fractions depend on draw temperature Td and draw ratio Rd . The fraction of disordered anisotropic amorphous phase changes very little with, the Td and increases with increasing Rd. Sum of the mass fractions of crystalline orthorhombic phase and the disordered anisotropic phase increases linearly as the same slope as the crystallinity Wc determined from DSC measurements with increasing Td or Rd and it is higher than the Wc for all the samples. The results show that the mass fraction of disordered anisotropic phase is partially devoted by the taut tie molecules (TTM s) in the amorphous state. The dependence of the disordered anisotropic phase on Td and Rd supports the mechanism of plastic deformation of fibre structure.

  13. Spectroscopic characterization of enzymatic flax retting: Factor analysis of FT-IR and FT-Raman data

    Science.gov (United States)

    Archibald, D. D.; Henrikssen, G.; Akin, D. E.; Barton, F. E.

    1998-06-01

    Flax retting is a chemical, microbial or enzymatic process which releases the bast fibers from the stem matrix so they can be suitable for mechanical processing before spinning into linen yarn. This study aims to determine the vibrational spectral features and sampling methods which can be used to evaluate the retting process. Flax stems were retted on a small scale using an enzyme mixture known to yield good retted flax. Processed stems were harvested at various time points in the process and the retting was evaluated by conventional methods including weight loss, color difference and Fried's test, a visual ranking of how the stems disintegrate in hot water. Spectroscopic measurements were performed on either whole stems or powders of the fibers that were mechanically extracted from the stems. Selected regions of spectra were baseline and amplitude corrected using a variant of the multiplicative signal correction method. Principal component regression and partial least-squares regression with full cross-validation were used to determine the spectral features and rate of spectral transformation by regressing the spectra against the retting time in hours. FT-Raman of fiber powders and FT-IR reflectance of whole stems were the simplest and most precise methods for monitoring the retting transformation. Raman tracks the retting by measuring the decrease in aromatic signal and subtle changes in the C-H stretching vibrations. The IR method uses complex spectral features in the fingerprint and carbonyl region, many of which are due to polysaccharide components. Both spectral techniques monitor the retting process with greater precision than the reference method.

  14. Infrared and Raman spectroscopic studies on iron oxide magnetic nano-particles and their surface modifications

    International Nuclear Information System (INIS)

    Iron oxide magnetic nano-particles (MNPs) have been prepared in aqueous solution by a modified co-precipitation method. Surface modifications have been carried out using tetraethoxysilane (TEOS), triethoxysilane (TES) and 3-aminopropyltrimethoxysilane (APTMS). The uncoated and coated particle products have been characterized with transmission electron microscope (TEM), energy dispersive X-ray (EDX) spectroscopy, infrared (IR) and Raman spectroscopy, and thermal gravimetric analysis (TGA). The particle sizes were determined from TEM images and found to have mean diameters of 13, 16 and 14 nm for Fe3O4, TES/Fe3O4 and APTMS/Fe3O4, respectively. IR and Raman spectroscopy has been applied to study the effect of thermal annealing on the uncoated and coated particles. The results have shown that magnetite nano-particles are converted to maghemite at 109 °C and then to hematite by 500 °C. In contrast, the study of the effect of thermal annealing of micro-crystalline magnetite by IR spectroscopy revealed that the conversion to hematite began by 300 °C and that no maghemite could be identified as an intermediate phase. IR spectra and TGA measurements revealed that the Si–H and 3-aminopropyl functional groups in TES and APTMS coated magnetite nano-particles decomposed below 500 °C while the silica layer around the iron oxide core remained unchanged. The molecular ratio of APTMS coating to iron oxide core was determined to be 1:7 from the TGA data. Raman scattering signals have indicated that MNPs could be converted to maghemite and then to hematite using increasing power of laser irradiation in a manner similar to that observed for thermal annealing. - Highlights: ► A modified co-precipitation method to prepare dispersive iron oxide magnetic nano-particles. ► Coating the nano-particle with different silicas. ► Estimating the numbers of iron oxide and 3-aminopropylsilica in the coated particles. ► Silica coating may help to protect iron oxide nano-particles from

  15. Raman spectroscopic studies on bismuth nanoparticles prepared by laser ablation technique

    Science.gov (United States)

    Onari, Seinosuke; Miura, Masaaki; Matsuishi, Kiyoto

    2002-09-01

    Bi nanoparticles are prepared by means of laser ablation in Ar atmosphere (0.2-10 Torr) with KrF (248 nm) excimer laser of the power 200 mJ. The size of the Bi particles estimated by TEM measurements is in the range 3-10 nm. Raman active E g mode shifts to a higher frequency and becomes broader for a sample prepared in a lower pressure of Ar atmosphere. However, the peak frequency and the bandwidth of A 1g mode show almost no change with the change of the particle size. These experimental results can be well explained by a phonon confinement model of Campbell and Fauchet by taking the phonon dispersion properties that the E g mode of the crystal has a large dependence on the wave numbers near the Γ point, but the A 1g mode is rather independent of the phonon wave numbers.

  16. Rapid bacterial antibiotic susceptibility test based on simple surface-enhanced Raman spectroscopic biomarkers

    Science.gov (United States)

    Liu, Chia-Ying; Han, Yin-Yi; Shih, Po-Han; Lian, Wei-Nan; Wang, Huai-Hsien; Lin, Chi-Hung; Hsueh, Po-Ren; Wang, Juen-Kai; Wang, Yuh-Lin

    2016-01-01

    Rapid bacterial antibiotic susceptibility test (AST) and minimum inhibitory concentration (MIC) measurement are important to help reduce the widespread misuse of antibiotics and alleviate the growing drug-resistance problem. We discovered that, when a susceptible strain of Staphylococcus aureus or Escherichia coli is exposed to an antibiotic, the intensity of specific biomarkers in its surface-enhanced Raman scattering (SERS) spectra drops evidently in two hours. The discovery has been exploited for rapid AST and MIC determination of methicillin-susceptible S. aureus and wild-type E. coli as well as clinical isolates. The results obtained by this SERS-AST method were consistent with that by the standard incubation-based method, indicating its high potential to supplement or replace existing time-consuming methods and help mitigate the challenge of drug resistance in clinical microbiology. PMID:26997474

  17. Femtosecond laser irradiation of indium phosphide in air: Raman spectroscopic and atomic force microscopic investigations

    Energy Technology Data Exchange (ETDEWEB)

    Bonse, J.; Wrobel, J.M.; Brzezinka, K.-W.; Esser, N.; Kautek, W

    2002-12-30

    Surface modification and ablation of crystalline indium phosphide was performed with single and double 130 fs pulses from a Ti:sapphire laser. The morphological features resulting from laser processing, have been investigated by means of micro Raman spectroscopy as well as by optical, atomic force and scanning electron microscopy. The studies indicate amorphous, ablated and recrystallized zones on the processed surface. In the single-pulse irradiation experimentsveral different threshold fluences could be assigned to the processes of melting, ablation and polycrystalline resolidification. Residual stress has been detected within the irradiated areas. Double-pulse exposure experiments have been analyzed in order to clarify the effect of cumulative damage in the ablation process of indium phosphide.

  18. Synergistic effects of atmospheric pressure plasma-emitted components on DNA oligomers: a Raman spectroscopic study.

    Science.gov (United States)

    Edengeiser, Eugen; Lackmann, Jan-Wilm; Bründermann, Erik; Schneider, Simon; Benedikt, Jan; Bandow, Julia E; Havenith, Martina

    2015-11-01

    Cold atmospheric-pressure plasmas have become of increasing importance in sterilization processes especially with the growing prevalence of multi-resistant bacteria. Albeit the potential for technological application is obvious, much less is known about the molecular mechanisms underlying bacterial inactivation. X-jet technology separates plasma-generated reactive particles and photons, thus allowing the investigation of their individual and joint effects on DNA. Raman spectroscopy shows that particles and photons cause different modifications in DNA single and double strands. The treatment with the combination of particles and photons does not only result in cumulative, but in synergistic effects. Profilometry confirms that etching is a minor contributor to the observed DNA damage in vitro. Schematics of DNA oligomer treatment with cold atmospheric-pressure plasma.

  19. Raman spectroscopic study of two dimensional polymer compounds of 2-aminopyrimidine

    Science.gov (United States)

    Akyuz, Sevim; Akyuz, Tanil

    2005-06-01

    The Raman spectra of the two dimensional layered polymer compounds, M(2APM) 2M'(CN) 4 {where M=Mn or Cd; and M'=Ni or Pt; 2APM=2-aminopyrimidine} are reported in the 70-4000 cm -1 region. Vibrational data suggests that compounds are similar in structure to the Hofmann type two dimensional coordination polymer compounds, formed with M(CN)4-2 ions bridged by M(2APM)2+2 cations. 2-Aminopyrimidine was coordinated to M(II) through one of the nitrogen atom of its heterocycle ring. Vibrational assignments are given for the bands arising from the tetracyanometallate layers and coordinated 2APM.

  20. Tip-Enhanced Raman Spectroscopic Imaging of Individual Carbon Nanotubes with Subnanometer Resolution.

    Science.gov (United States)

    Liao, Menghan; Jiang, Song; Hu, Chunrui; Zhang, Rui; Kuang, Yanmin; Zhu, Jiazhe; Zhang, Yang; Dong, Zhenchao

    2016-07-13

    Individual carbon nanotubes (CNTs) have been investigated by tip-enhanced Raman spectroscopy (TERS) using silver tips on the Ag(111) substrate with a low-temperature ultrahigh-vacuum scanning tunneling microscope. Thanks to the strong and highly localized plasmonic field offered by the silver nanogap, the spatial resolution of TERS on CNTs is driven down to about 0.7 nm. Such a high spatial resolution allows to visualize in real space the spatial extent of the defect-induced D-band scattering, to track the strain-induced spectral evolution, and to resolve the spectral differences between the inner and the outer sides of a bent CNT, all at the nanometer scale. PMID:27348072

  1. Spectroscopic (FT-IR, FT-Raman and NMR) and computational studies on 3-methoxyaniline

    Science.gov (United States)

    Sivaranjini, T.; Periandy, S.; Govindarajan, M.; Karabacak, M.; Asiri, A. M.

    2014-01-01

    In this work, the molecular structure, vibrational, UV and NMR spectra of 3-methoxyaniline (abbreviated as 3MOA, C7H9NO) were studied. The FT-IR and FT-Raman spectra were recorded. The ground-state molecular geometry and vibrational frequencies were calculated by using the Hartree-Fock (HF) and density functional theory (DFT)/B3LYP methods and 6-311++G(d, p) as a basis set. The fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Comparison of the observed fundamental vibrational frequencies of 3MOA with calculated results by HF and DFT methods indicates that B3LYP is superior to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. A study on the Mulliken atomic charges, the electronic properties were performed by time-dependent DFT (TD-DFT) approach, Frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed and compared with methoxybenzene and aniline. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the 3MOA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  2. Expanding the analytical toolbox for identity testing of pharmaceutical ingredients: Spectroscopic screening of dextrose using portable Raman and near infrared spectrometers.

    Science.gov (United States)

    Srivastava, Hirsch K; Wolfgang, Steven; Rodriguez, Jason D

    2016-03-31

    In the pharmaceutical industry, dextrose is used as an active ingredient in parenteral solutions and as an inactive ingredient (excipient) in tablets and capsules. In order to address the need for more sophisticated analytical techniques, we report our efforts to develop enhanced identification methods to screen pharmaceutical ingredients at risk for adulteration or substitution using field-deployable spectroscopic screening. In this paper, we report our results for a study designed to evaluate the performance of field-deployable Raman and near infrared (NIR) methods to identify dextrose samples. We report a comparison of the sensitivity of the spectroscopic screening methods against current compendial identification tests that rely largely on a colorimetric assay. Our findings indicate that NIR and Raman spectroscopy are both able to distinguish dextrose by hydration state and from other sugar substitutes with 100% accuracy for all methods tested including spectral correlation based library methods, principal component analysis and classification methods. PMID:26965331

  3. Can surface-enhanced Raman scattering serve as a channel for strong optical pumping?

    Science.gov (United States)

    Haslett, T. L.; Tay, L.; Moskovits, M.

    2000-07-01

    The surface-enhanced Raman scattering spectra of a number of dye and colorless molecules adsorbed on deposited coloidal silver films were systematically studied as a function of power and position using a Raman microscope. The anti-Stokes portions of the spectra of the dyes reproducibly show line intensities much greater than what is expected on the basis of the equilibrium population of the excited vibrational states, even at the lowest incident light intensities used. This behavior was observed previously and attributed to optical pumping of vibrationally excited states of the molecules by unusually intense surface-enhanced Raman transitions, [Phys. Rev. Lett. 76, 2444 (1996)] suggesting either uncommonly large Raman cross-sections or very intense local field strengths exceeding those encountered in the most powerful currently available lasers. Based on this work, however, we ascribe the apparently large anti-Stokes intensities primarily to a difference in the Stokes and anti-Stokes Raman cross-sections resulting from resonance or pre-resonance Raman processes in the adsorbate-surface complex rather than to strongly nonequilibrium populations in the molecular vibrational states. Finally, we observed no significant inhomogeneity in the Raman enhancement in the images of the deposited silver coloid samples down to spatial resolutions of ˜1 μm.

  4. Optical phonons and polariton dispersions of congruent LiNbO3 studied by far-infrared spectroscopic ellipsometry and Raman scattering

    Science.gov (United States)

    Kojima, Seiji; Kanehara, Kazuki; Hoshina, Takuya; Tsurumi, Takaaki

    2016-10-01

    IR active optical modes and phonon–polaritons with E(x) and A1(z) symmetries were studied in a ferroelectric congruent lithium niobate crystal. The real and imaginary parts of a dielectric constant along the a- and c-axes were accurately determined by far-infrared spectroscopic ellipsometry (FIRSP) from 40 to 700 cm‑1. For the nine transverse optical (TO) modes with E(x) symmetry, it was difficult to observe the 5th E(TO5) mode at 361 cm‑1 and the 9th E(TO9) mode at 665 cm‑1 by Raman scattering owing to the very low Raman intensity, while these modes were clearly observed by FIRSP. In contrast, the 6th E(TO6) mode at 371 cm‑1 was not observed by FIRSP owing to the very weak absorption, while it was clearly observed by Raman scattering. All the four TO modes with A1(z) symmetry were clearly observed independently by FIRSP and Raman scattering. The dispersion relations of phonon–polaritons including the damping of polaritons were determined using the real and imaginary parts of a polariton wavevector calculated from complex dielectric constants. The polariton dispersion of the lowest A1(z) mode at 254 cm‑1 is in agreement with the previous forward Raman scattering experiment; however, any anticrossing predicted by the previous impulsive Raman scattering experiment was not observed.

  5. Non-destructive Analysis of the Nuclei of Transgenic Living Cells Using Laser Tweezers and Near-infrared Raman Spectroscopic Technique

    Institute of Scientific and Technical Information of China (English)

    Wei Tang; Ronald J. Newton; Chang-An Xie; Yong-Qing Li; Nicki Whitley

    2005-01-01

    Transgenic cell lines of loblolly pine (Pinus taeda L.) were analyzed by a compact laser-tweezers-Raman-spectroscopy (LTRS) system in this investigation. A low power diode laser at 785 nm was used for both laser optical trapping of single transgenic cells and excitation for near-infrared Raman spectroscopy of the nuclei of synchronized cells, which were treated as single organic particles, at the S-phase of the cell cycle. Transgenic living cells with gfp and uidA genes were used as biological samples to test this LTRS technique. As expected, different Raman spectra were observed from the tested biological samples. This technique provides a high sensitivity and enables real-time spectroscopic measurements of transgenic cell lines. It could be a valuable tool for the study of the fundamental cell and molecular biological process by trapping single nucleus and by providing a wealth of molecular information about the nuclei of cells.

  6. Imaging and spectroscopic analysis of single microdroplets containing p-cresol using the near-infrared laser tweezers/Raman microprobe system

    Science.gov (United States)

    Ajito, Katsuhiro; Morita, Masao

    1999-06-01

    The near-infrared (NIR) laser tweezers/Raman microprobe system features two charge-coupled device (CCD) cameras with holographic notch filters (HNFs) for the imaging and spectroscopic analysis of molecules in a single microdroplet (MD). One CCD camera and a HNF are used to record an image of the laser microprobe in a trapped MD. The other CCD camera and two HNFs are used with a polychromator to obtain a Raman spectrum of molecules in the MD. A dielectric multilayer coated beam splitter divides the scattered NIR light into two optical paths for the cameras. The system provides sufficient sensitivity to obtain a Raman spectrum of p-cresol contained in a single picoliter toluene MD and sufficient spatial resolution to record an image of the laser microprobe in a trapped MD simultaneously. Furthermore, a difference in the solubility for the p-cresol in bulk solvent and in the MD solvent was clearly observed using this system.

  7. Layered Gold and Titanium Dioxide Substrates for Improved Surface Enhanced Raman Spectroscopic Sensing.

    Science.gov (United States)

    Strobbia, Pietro; Henegar, Alex J; Gougousi, Theodosia; Cullum, Brian M

    2016-08-01

    This manuscript describes a simple process for fabricating gold-based, multi-layered, surface-enhanced Raman scattering (SERS) substrates that can be applied to a variety of different nanostructures, while still providing multi-layer enhancement factors comparable to those previously achieved only with optimized silver/silver oxide/silver substrates. In particular, gold multi-layered substrates generated by atomic layer deposition (ALD) have been fabricated and characterized in terms of their optimal performance, revealing multi-layer enhancements of 2.3-fold per spacer layer applied. These substrates were fabricated using TiO2 as the dielectric spacer material between adjacent gold layers, with ALD providing a conformal thin film with high surface coverage and low thickness. By varying the spacer layer thicknesses from sub-monolayer (non-contiguous) films through multiple TiO2 layer thick films, the non-monotonic spacer layer thickness response has been elucidated, revealing the importance of thin, contiguous dielectric spacer layers for optimal enhancement. Furthermore, the extended shelf life of these gold multi-layered substrates was characterized, demonstrating usable lifetimes (i.e. following storage in ambient conditions) of greater than five months, with the further potential for simple limited electrochemical regeneration even after this time. PMID:27329834

  8. IR and Raman spectroscopic studies of sol–gel derived alkaline-earth silicate glasses

    Indian Academy of Sciences (India)

    Angelos G Kalampounias

    2011-04-01

    IR and Raman spectroscopies have been utilized to study the structure and vibrational modes of sol–gel-derived binary silicate glasses. The present study is motivated by the immense geological significance and focuses on the MO–SiO2 (M = Ca, Mg) binary systems in an effort to unveil the role of the CaO and MgO modifiers when incorporated to the 3D silica structure. Glasses in the composition range = 0, 0.1, 0.2, 0.3 and 0.4 prepared by the sol–gel method were compared with the corresponding glasses formed by appropriate mixing of SiO2 and MO powders through melting and fast cooling. The vibrational spectra of the sol–gel-derived glasses have revealed considerable changes in relative intensities as a function of the MO mole fraction. These changes signify structural modifications on the silica network. The population of the 3 species was found to increase for both modified silicate systems. The rate of increase is more pronounced in the CaO–SiO2 glasses. The extent of network depolymerization in the porous glass is higher at the same content of alkaline earth oxide compared to the bulk glass. The results are indicative of a more `defective’ nature of the sol–gel glasses compared to the corresponding melt-quenched ones.

  9. Combined X-Ray and Raman Spectroscopic Techniques for the Characterization of Sea Spray Aerosol

    Science.gov (United States)

    Aller, J. Y.; Alpert, P. A.; Knopf, D. A.; Kilthau, W.; Bothe, D.; Charnawskas, J. C.; Gilles, M. K.; OBrien, R. E.; Moffet, R.; Radway, J.

    2014-12-01

    Sea spray aerosol along with mineral dust dominates the global mass flux of particles to the atmosphere. Marine aerosol particles are of particular interest because of their continual impact on cloud formation, precipitation, atmospheric chemical processes, and thus global climate. Here we report on the physical/chemical characteristics of sub-surface waters, aerosolized sea spray particles, and particles/organic species present in surface microlayer (SML) samples collected during oceanic field campaigns and generated during laboratory experiments, revealing a biogenic primary source of the organic fraction of airborne particles. We also report on ice nucleation experiments with aerosolized particles collected during the May 2014 WACS II North Atlantic cruise and with laboratory generated exudate material from diatom cultures with the potential to impact cirrus and mixed phase clouds. Physicochemical analyses using a multi-modal approach which includes Scanning Transmission X-ray Microscopy coupled with Near-Edge Absorption Fine Structure Spectroscopy (STXM/NEXAFS) and Raman spectroscopy confirm the presence and chemical similarity of polysaccharide-rich transparent exopolymer (TEP) material and proteins in both SML sea spray aerosol and ice forming aerosol particles, regardless of the extent of biological activity in surface waters. Our results demonstrate a direct relationship between the marine environment and composition of marine aerosol through primary particle emission.

  10. Basic Design of UV Rotational Raman Lidar for Temperature Measurement of the Troposphere

    OpenAIRE

    SUN, Dongsong; Kobayashi, Takao

    1999-01-01

    Basic analysis of practical rotational Raman lidar (laser radar) system for the temperature measurement of the troposphere is presented. The eye-safe UV laser of 355nm wavelength is selected as the transmitter and anti-Stokes lines of the rotational Raman backscatter are used for the temperature determination. From the system design, it is concluded that the temperature accuracy of 1 K can be obtained up to 10km height with 5W average laser system.

  11. Sequence dependent DNA conformations: Raman spectroscopic studies and a model of action of restriction enzymes

    International Nuclear Information System (INIS)

    Raman spectra have been examined to clarify the polymorphic forms of DNA, A, B, and Z forms. From an analysis the authors found that the guanine ring breathing vibration is sensitive to its local conformation. Examination of nine crystals of guanosine residues in which the local conformations are well established revealed that a guanosine residue with a C3'endo-anti gives a strong line at 666+-2 cm/sup -1/, O4'endo-anti at 682 cm/sup -1/, C1'exo-anti at 673 cm/sup -1/, C2'endo-anti at 677 cm/sup -1/ and syn-forms around 625 cm/sup -1/. Using this characteristic line, they were able to obtain the local conformations of guanosine moieties in poly(dG-dC). Such a sequence derived variation is suggested to be recognized by sequence specific proteins such as restriction enzymes. The authors found a correlation between sequence dependent DNA conformation and a mode of action of restriction enzymes. The cutting mode of restriction enzymes is classified into three groups. The classification of whether the products have blunt ends, two-base-long cohesive ends, or four-base-long cohesive ends depends primarily on the substrate, not on the enzyme. It is suggested that sequence dependent DNA conformation causes such a classification by the use of the Calladine-Dickerson analysis. In the recognition of restriction enzymes, the methyl group in a certain sequence is considered to play an important role by changing the local conformation of DNA

  12. Infrared and Raman spectroscopic features of the self-interstitial defect in diamond from exact-exchange hybrid DFT calculations.

    Science.gov (United States)

    Salustro, Simone; Erba, Alessandro; Zicovich-Wilson, Claudio M; Nöel, Yves; Maschio, Lorenzo; Dovesi, Roberto

    2016-08-01

    Quantum-mechanical calculations are performed to investigate the structural, electronic, and infrared (IR) and Raman spectroscopic features of one of the most common radiation-induced defects in diamond: the "dumb-bell" 〈100〉 split self-interstitial. A periodic super-cell approach is used in combination with all-electron basis sets and hybrid functionals of density-functional-theory (DFT), which include a fraction of exact non-local exchange and are known to provide a correct description of the electronic spin localization at the defect, at variance with simpler formulations of the DFT. The effects of both defect concentration and spin state are explicitly addressed. Geometrical constraints are found to prevent the formation of a double bond between the two three-fold coordinated carbon atoms. In contrast, two unpaired electrons are fully localized on each of the carbon atoms involved in the defect. The open-shell singlet state is slightly more stable than the triplet (the energy difference being just 30 meV, as the unpaired electrons occupy orthogonal orbitals) while the closed-shell solution is less stable by about 1.55 eV. The formation energy of the defect from pristine diamond is about 12 eV. The Raman spectrum presents only two peaks of low intensity at wave-numbers higher than the pristine diamond peak (characterized by normal modes extremely localized on the defect), whose positions strongly depend on defect concentration as they blue shift up to 1550 and 1927 cm(-1) at infinite defect dilution. The first of these peaks, also IR active, is characterized by a very high IR intensity, and might then be related to the strong experimental feature of the IR spectrum occurring at 1570 cm(-1). A second very intense IR peak appears at about 500 cm(-1), which, despite being originated from a "wagging" motion of the self-interstitial defect, exhibits a more collective, less localized character. PMID:27326546

  13. Nonlinear interferometric vibrational imaging

    CERN Document Server

    Marks, D L

    2003-01-01

    Coherent Anti-Stokes Raman Scattering (CARS) processes are ``coherent,'' but the phase of the anti-Stokes radiation is usually lost by most incoherent spectroscopic CARS measurements. We propose a novel Raman microscopy imaging method called Nonlinear Interferometric Vibrational Imaging, which measures Raman spectra by obtaining the temporal anti-Stokes signal through nonlinear interferometry. With a more complete knowledge of the anti-Stokes signal, we show through simulations that a high-resolution Raman spectrum can be obtained of a molecule in a single pulse using broadband radiation. This could be useful for identifying the three-dimensional spatial distribution of molecular species in tissue.

  14. Anti-Stokes luminescence o Ln2O2S: Er(3+), Yb(3+) in triplexes excited in the 0.9. 1.53 and 1.59-micron ranges, part 2

    Science.gov (United States)

    Kurochkin, A. V.; Mailibaeva, L. M.; Manashirov, O. Ya.; Sattarov, D. K.; Smirnov, V. B.

    1992-10-01

    Studies are reported of IR anti-Stokes luminescence of three Ln2O2S:Er(sup 3 +), Yb(sup 3 +) luminophores incorporated in triplexes under excitation by different IR sources in the 0.93, 1.53, and 1.59 mu m ranges. Spectra of three different anti-Stokes luminophores (Ln = Y, Fd and La) are examined and the fine structure of each individual anti-Stokes band is analyzed. The appearance of these bands is explained on the basis of energy structures of doping Er(sup 3 +) and Yb(sup 3 +) ions in the studied oxysulfides. The anti-Stokes luminescence spectra excited by IR sources with lambda(sub max) = 0.93 and 1.53 mu m are compared. For the same oxysulfides doped by Er(sup 3 +) only or by both Er(sup 3 +) and Yb(sup 3 +), differences in the fine structures of the 0.99-micron band are explained, this band being the most promising for conversion of IR radiation in the 1.4-1.7 -micron range. The results obtained indicate the possibility to develop, using the anti-Stokes luminophores studied, a uniform polychromatic IR image converter and to suggest ways for its further improvement.

  15. Anti-Stokes luminescence of Ln2O2S: Er3+, Yb3+ in triplexes excited in the 0.93, 1.06, 1.53, and 1.59-μm ranges. Part 2

    International Nuclear Information System (INIS)

    Studies are reported of IR anti-Stokes luminescence of three Ln2O2S: Er3+, Yb3+ luminophores incorporated in triplexes under excitation by different IR sources in the 0.93, 1.53, and 1.59-μm ranges. Spectra of three different anti-Stokes luminophores (Ln=Y, Gd, and La) are examined and the fine structure of each individual anti-Stokes band is analyzed. The appearance of these bands is explained on the basis of energy structures of doping Er3+ and Yb3+ ions in the studied oxysulfides. The anti-Stokes luminescence spectra excited by IR sources with λmax=0.93 and 1.53 μm are compared. For the same oxysulfides doped by Er3+ only or by both Er3+ and Yb3+, differences in the fine structures of the 0.99-μm band are explained, this band being the most promising for conversion of IR radiation in the 1.4-1.7-μm range. The results obtained indicate the possibility to develop, using the anti-Stokes luminophores studied, a uniform polychromatic IR image converter and to suggest ways for its further improvement. 17 refs., 4 figs., 1 tab

  16. Diffusion Raman et luminescence dans des aerogels de silice purs ou dopes Dy

    Science.gov (United States)

    Guerri, F.; Fabre, F.; Zwick, A.; Bournett, D.

    1994-02-01

    Light scattering studies of pure and Dy doped aerogels are presented. Careful examination of Stokes and anti-Stokes spectra allow the discrimination between Raman and luminescence processes. It is shown that in pure aerogels, scattered intensity is due to Raman processes only, and the density of vibrational states does not exhibit any singularity. The fractal properties of the structure imply modifications not only in the spectral distribution of the low frequency modes (usually labelled phonons and fractons) but alsoin the high frequency one, at least up to 600 cm-1. In Dy-doped dense silica, coupling between electronic and vibronic excitations is evidenced by the presence of anti-Stokes luminescence. In Dy-doped aerogels, the enlarged Dy3+ electronic levels, strongly coupled with vibrational states give rise to emission processes traducing the response of the sample as a whole, rather than resonant Raman scattering or luminescence processes.

  17. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    Science.gov (United States)

    Dey, S.; Banik, M.; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2016-01-01

    Surface-enhanced Raman scattering (SERS) from bipyridyl ethylene adsorbed on gold dumbbells shows Fano-like spectra at high incident light intensity. This is accompanied by an increased electronic temperature, while no vibrational anti-Stokes scattering is observed. Theory indicates that interference between vibrational and electronic Raman scattering can yield such asymmetric scattering lineshapes. The best fit to observations is however obtained by disregarding this coupling and accounting for the detailed lineshape of the continuous electronic component of the SERS.

  18. Observation and analysis of Fano-like lineshapes in the Raman spectra of molecules adsorbed at metal interfaces

    OpenAIRE

    Dey, S; Banik, M; Hulkko, E.; Rodriguez, K.; Apkarian, V. A.; Galperin, M.; Nitzan, A.

    2015-01-01

    Surface enhanced Raman spectra from molecules (bipyridyl ethylene) adsorbed on gold dumbells are observed to become increasingly asymmetric (Fano-like) at higher incident light intensity. The electronic temperature (inferred from the anti-Stokes (AS) electronic Raman signal increases at the same time while no vibrational AS scattering is seen. These observations are analyzed by assuming that the molecule-metal coupling contains an intensity dependent contribution (resulting from light-induced...

  19. Molecular structure and spectroscopic properties of 4-nitrocatechol at different pH: UV-visible, Raman, DFT and TD-DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Cornard, Jean-Paul [Laboratoire de Spectrochimie Infrarouge and Raman LASIR, CNRS UMR 8516, Universite des Sciences et Technologies de Lille Bat C5, 59655 Villeneuve d' Ascq Cedex (France)]. E-mail: cornard@univ-lille1.fr; Rasmiwetti [Laboratoire de Spectrochimie Infrarouge and Raman LASIR, CNRS UMR 8516, Universite des Sciences et Technologies de Lille Bat C5, 59655 Villeneuve d' Ascq Cedex (France); Merlin, Jean-Claude [Laboratoire de Spectrochimie Infrarouge and Raman LASIR, CNRS UMR 8516, Universite des Sciences et Technologies de Lille Bat C5, 59655 Villeneuve d' Ascq Cedex (France)

    2005-03-14

    We investigated theoretically, by density functional theoretical calculations and by vibrational and electronic spectroscopies, the structure and the molecular spectroscopic properties of the 4-nitrocatechol molecule with varying pH. The lower energy stable structures of the neutral, monoanion and dianion forms were compared, and influence of water solvation was examined. The Raman and UV-visible spectra of 4-nitrocatechol and of its singly deprotonated form were recorded by varying the pH from 2 to 9. A calculation of the vibrational frequencies has allowed a complete assignment of the Raman spectra of the two forms of 4-nitrocatechol, and has permitted to investigate the evolution of vibrational normal modes upon deprotonation. Based on the molecular orbital analysis and the time dependent DFT (TD-DFT) calculations, we discussed the electronic structure and the assignment of the absorption bands in the electronic spectra of 4-nitrocatechol and mono-deprotonated 4-nitrocatechol.

  20. Molecular structure and spectroscopic properties of 4-nitrocatechol at different pH: UV visible, Raman, DFT and TD-DFT calculations

    Science.gov (United States)

    Cornard, Jean-Paul; Rasmiwetti; Merlin, Jean-Claude

    2005-03-01

    We investigated theoretically, by density functional theoretical calculations and by vibrational and electronic spectroscopies, the structure and the molecular spectroscopic properties of the 4-nitrocatechol molecule with varying pH. The lower energy stable structures of the neutral, monoanion and dianion forms were compared, and influence of water solvation was examined. The Raman and UV-visible spectra of 4-nitrocatechol and of its singly deprotonated form were recorded by varying the pH from 2 to 9. A calculation of the vibrational frequencies has allowed a complete assignment of the Raman spectra of the two forms of 4-nitrocatechol, and has permitted to investigate the evolution of vibrational normal modes upon deprotonation. Based on the molecular orbital analysis and the time dependent DFT (TD-DFT) calculations, we discussed the electronic structure and the assignment of the absorption bands in the electronic spectra of 4-nitrocatechol and mono-deprotonated 4-nitrocatechol.

  1. Broadband Fiber Raman Power-Amplifier for Narrow Linewidth Tunable Seed Lasers Used in Spectroscopic Sensing Project

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose an energy and space efficient high power continuous wave (cw) narrow linewidth broadband fiber Raman amplifier (FRA) with spectrally tunable...

  2. Raman spectroscopic analysis of cyanogenic glucosides in plants: development of a Flow Injection Surface-Enhanced Raman Scatter (FI-SERS) method for determination of cyanide

    DEFF Research Database (Denmark)

    Thygesen, Lisbeth Garbrecht; Jørgensen, Kirsten; Møller, Birger Lindberg;

    2004-01-01

    /lotaustralin in leaves and roots from a medium cyanogenic cassava variety were obtained in situ using a Fourier transform near-infrared (FT-NIR) Raman interferometer with a 1064 nm laser, but the signal was very weak and difficult to obtain. A spectrum containing a signal from the CN bond of dhurrin in a freeze......Cyanogenic glucosides were studied using Raman spectroscopy. Spectra of the crystal forms of linamarin, linustatin, neolinustatin, amygdalin, sambunigrin, and dhurrin were obtained using a Raman spectrograph microscope equipped with a 532 nm laser. The position of the signal from the CdropN triple...... bond of the cyanohydrin group was influenced by the nature of the side group and was above 2240 cm(-1) for the three cyanogenic glucosides that contain a neigh- boring aromatic ring, and below or partially below 2240 cm-1 for the non-aromatic cyanoglucosides. Signals from the CN bond of linamarin...

  3. Coherent Raman Studies of Shocked Liquids

    Science.gov (United States)

    McGrane, Shawn; Brown, Kathryn; Dang, Nhan; Bolme, Cynthia; Moore, David

    2013-06-01

    Transient vibrational spectroscopies offer the potential to directly observe time dependent shock induced chemical reaction kinetics. We report recent experiments that couple a hybrid picosecond/femtosecond coherent anti-Stokes Raman spectroscopy (CARS) diagnostic with our tabletop ultrafast laser driven shock platform. Initial results on liquids shocked to 20 GPa suggest that sub-picosecond dephasing at high pressure and temperature may limit the application of this nonresonant background free version of CARS. Initial results using interferometric CARS to increase sensitivity and overcome these limitations will be presented.

  4. Nanosecond microscopy with a high spectroscopic resolution

    CERN Document Server

    Heinrich, C; Ritsch-Marte, M; Bernet, Stefan; Heinrich, Christoph; Ritsch-Marte, Monika

    2005-01-01

    We demonstrate coherent anti-Stokes Raman scattering (CARS) microscopy in a wide-field setup with nanosecond laser pulse excitation. In contrast to confocal setups, the image of a sample can be recorded with a single pair of excitation pulses. For this purpose the excitation geometry is specially designed in order to satisfy the phase matching condition over the whole sample area. The spectral, temporal and spatial sensitivity of the method is demonstrated by imaging test samples, i.e. oil vesicles in sunflower seeds, on a nanosecond timescale. The method provides snapshot imaging in 3 nanoseconds with a spectral resolution of 25 wavenumbers (cm$^{-1}$).

  5. Anti-Stokes effect CCD camera and SLD based optical coherence tomography for full-field imaging in the 1550nm region

    Science.gov (United States)

    Kredzinski, Lukasz; Connelly, Michael J.

    2012-06-01

    Full-field Optical coherence tomography is an en-face interferometric imaging technology capable of carrying out high resolution cross-sectional imaging of the internal microstructure of an examined specimen in a non-invasive manner. The presented system is based on competitively priced optical components available at the main optical communications band located in the 1550 nm region. It consists of a superluminescent diode and an anti-stokes imaging device. The single mode fibre coupled SLD was connected to a multi-mode fibre inserted into a mode scrambler to obtain spatially incoherent illumination, suitable for OCT wide-field modality in terms of crosstalk suppression and image enhancement. This relatively inexpensive system with moderate resolution of approximately 24um x 12um (axial x lateral) was constructed to perform a 3D cross sectional imaging of a human tooth. To our knowledge this is the first 1550 nm full-field OCT system reported.

  6. Theory and applications of confocal micro-Raman spectroscopy on hybrid polymer coatings and PDMS membranes and spectroscopic studies of doped B2O3-Bi2O3 glass systems

    OpenAIRE

    Baia, Gheorghe Lucian

    2003-01-01

    The thesis consists of two major parts. The first part contains a theoretical-experimental study of confocal micro-Raman spectroscopy on hybrid polymer coatings and an application of this spectroscopic method on PDMS-membranes. The theoretical-experimental study includes the application of a model that describes the influence of the refraction effect on the focus length on confocal Raman experiments, and the development of a new model that additionally takes into account the effect of diffrac...

  7. Near infrared Raman spectroscopic study of reactive gliosis and the glial scar in injured rat spinal cords

    Science.gov (United States)

    Saxena, Tarun; Deng, Bin; Lewis-Clark, Eric; Hoellger, Kyle; Stelzner, Dennis; Hasenwinkel, Julie; Chaiken, Joseph

    2010-02-01

    Comparative Raman spectra of ex vivo, saline-perfused, injured and healthy rat spinal cord as well as experiments using enzymatic digestion suggest that proteoglycan over expression may be observable in injured tissue. Comparison with authentic materials in vitro suggest the occurrence of side reactions between products of cord digestion with chondroitinase (cABC) that produce lactones and similar species with distinct Raman features that are often not overlapped with Raman features from other chemical species. Since the glial scar is thought to be a biochemical and physical barrier to nerve regeneration, this observation suggests the possibility of using near infrared Raman spectroscopy to study disease progression and explore potential treatments ex vivo and if potential treatments can be designed, perhaps to monitor potential remedial treatments within the spinal cord in vivo.

  8. From molecular fragments to crystals: a UV Raman spectroscopic study on the mechanism of Fe-ZSM-5 synthesis.

    Science.gov (United States)

    Fan, Fengtao; Sun, Keju; Feng, Zhaochi; Xia, Haian; Han, Bo; Lian, Yuxiang; Ying, Pinliang; Li, Can

    2009-01-01

    The nucleation process of iron-exchanged zeolite Fe-ZSM-5, from the assembly of distorted tetrahedrally coordinated iron species and silicate rings in the precursor to the final Fe-ZSM-5 crystals, as well as variations in the coordination environment of iron, were studied by UV resonance Raman spectroscopy and complementary techniques.The entire sequence of crystallization events of Fe-ZSM-5 was monitored by UV Raman spectroscopy in combination with HRTEM, UV/Vis spectroscopy, X-ray diffraction patterns, and periodic DFT calculations. Fe-ZSM-5 was synthesized by an organic-free method to avoid signal interference from the organic template in Raman spectra. Framework iron atoms with resonance Raman bands at 516, 1115, and 1165 cm(-1), and a Raman band at 1016 cm(-1) are detected for Fe-ZSM-5. In the early stage of Fe-ZSM-5 synthesis, the precursor contains iron atoms in distorted tetrahedral coordination and five- and six-membered silicate rings. Nucleation by aggregation of the precursor species was monitored by UV Raman spectroscopy based on the resonance Raman effect, and confirmed by periodic DFT calculations. Evolution of iron species on the surface and in the bulk phase was monitored by UV Raman spectroscopy with excitation at 244 and 325 nm, as well as HRTEM. Nucleation takes place first in the core of the amorphous particles, and crystalline nuclei with Fe-ZSM-5 structure are formed in the core by consuming the amorphous shell. Finally the amorphous particles are completely transformed into Fe-ZSM-5 crystals. PMID:19197930

  9. A Raman spectroscopic study of zircons on micro-scale and Its significance in explaining the origin of zircons

    CERN Document Server

    Bao, Xuezhao; Lu, Songnian

    1998-01-01

    The magmatic and metamorphic zircons were investigated with Raman spectrum microprobe analysis. We found notable differences between these two kinds of zircons exhibited by the variation trend of Raman peak intensity from core to rim of a crystal. In magmatic zircons, the intensity and the ratio H/W of Raman spectrum peaks gradually decrease from core to rim of a crystal, which is produced by an increase in metamictization degree and suggests an increase in U and Th concentrations from core to rim. In metamorphic zircons, there are two kinds of crystals according to their Raman spectra: the first group of zircons exhibits a variation trend opposite to those of magmatic zircons, tending to increase in the Raman peak intensity and H/W value from core to rim of a crystal, which is produced by a decrease in metamictization degree and indicates a decrease of U and Th concentrations from core to rim of a crystal. The second group of zircons exhibits no change in Raman peak intensity and H/W value through a crystal....

  10. Revisiting the Young's double slit experiment for background-free nonlinear Raman spectroscopy and microscopy.

    Science.gov (United States)

    Gachet, David; Brustlein, Sophie; Rigneault, Hervé

    2010-05-28

    In the Young's double slit experiment, the spatial shift of the interference pattern projected onto a screen is directly related to the phase difference between the fields diffracted by the two slits. We apply this property to fields emitted by nonlinear processes and thus demonstrate background-free coherent anti-Stokes Raman scattering microscopy near an axial interface between a resonant and a nonresonant medium. This method is relevant to remove the nonresonant background in other coherent resonant processes.

  11. Quantum Noise Reduction and Generalized Two-Mode Squeezing in a Cavity Raman Laser

    OpenAIRE

    Druhl, K.; Windenberger, C.

    1998-01-01

    We study a generalized notion of two-mode squeezing for the Stokes and anti-Stokes fields in a model of a cavity Raman laser, which leads to a significant reduction in decoherence or quantum noise. The model comprises a loss-less cavity with classical pump, unsaturated medium and arbitrary homogeneous broadening and dispersion. Allowing for arbitrary linear combinations of the two modes in the definition of quadrature variables, we find that there always exists a combination of the two output...

  12. Phase-interfacial stimulated Raman scattering generated in strongly pumped water.

    Science.gov (United States)

    Yuan, Hong; Gai, Baodong; Liu, Jinbo; Guo, Jingwei; Li, Hui; Hu, Shu; Deng, Liezheng; Jin, Yuqi; Sang, Fengting

    2016-07-15

    We have observed unusual blue-shifted radiations in water pumped by a strong 532-nm nanosecond laser. Properties including divergence, polarizations, and pulse shapes of the unusual radiations are measured and compared with those of the regular stimulated Raman scattering (SRS) in water. The unusual radiations are attributed to the parametric anti-Stokes SRS that occurs on the interface of water and ionization plasma (or gas) formed in the laser-induced breakdown of water. PMID:27420529

  13. Label-free assessment of adipose-derived stem cell differentiation using coherent anti-Stokes Raman scattering and multiphoton microscopy

    OpenAIRE

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

    2012-01-01

    ABSTRACT. 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...

  14. Graphitic carbon nanospheres: A Raman spectroscopic investigation of thermal conductivity and morphological evolution by pulsed laser irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Radhe; Sahoo, Satyaprakash, E-mail: satya504@gmail.com, E-mail: rkatiyar@hpcf.upr.edu; Chitturi, Venkateswara Rao; Katiyar, Ram S., E-mail: satya504@gmail.com, E-mail: rkatiyar@hpcf.upr.edu [Department of Physics, University of Puerto Rico, San Juan, Puerto Rico 00936-8377 (United States)

    2015-12-07

    Graphitic carbon nanospheres (GCNSs) were prepared by a unique acidic treatment of multi-walled nanotubes. Spherical morphology with a narrow size distribution was confirmed by transmission electron microscopy studies. The room temperature Raman spectra showed a clear signature of D- and G-peaks at around 1350 and 1591 cm{sup −1}, respectively. Temperature dependent Raman scattering measurements were performed to understand the phonon dynamics and first order temperature coefficients related to the D- and G-peaks. The temperature dependent Raman spectra in a range of 83–473 K were analysed, where the D-peak was observed to show a red-shift with increasing temperature. The relative intensity ratio of D- to G-peaks also showed a significant rise with increasing temperature. Such a temperature dependent behaviour can be attributed to lengthening of the C-C bond due to thermal expansion in material. The estimated value of the thermal conductivity of GCNSs ∼0.97 W m{sup −1} K{sup −1} was calculated using Raman spectroscopy. In addition, the effect of pulsed laser treatment on the GCNSs was demonstrated by analyzing the Raman spectra of post irradiated samples.

  15. Influence of Raman effect on the noise characteristics in a dual pump FOPA

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-peng; YU Chong-xiu; DENG Yun-yi; SANG Xin-zhu; YUAN Jin-hui; RAO Lan

    2011-01-01

    Influence induced by Raman effect on the noise characteristics of a depleted and lossy dual pump fiber optical parametric amplifier (FOPA) is investigated.Taking the Raman effect into account,the modified coupled amplitude equations are firstly built,then the influences of Raman effect on the Stokes and anti-Stokes wavelengths with different initial signal powers are further analyzed.Besides,the effect on the FOPA gain is also shown with the same initial signal power and constant noise figure (NF).

  16. Measuring changes in chemistry, composition, and molecular structure within hair fibers by infrared and Raman spectroscopic imaging

    Science.gov (United States)

    Zhang, Guojin; Senak, Laurence; Moore, David J.

    2011-05-01

    Spatially resolved infrared (IR) and Raman images are acquired from human hair cross sections or intact hair fibers. The full informational content of these spectra are spatially correlated to hair chemistry, anatomy, and structural organization through univariate and multivariate data analysis. Specific IR and Raman images from untreated human hair describing the spatial dependence of lipid and protein distribution, protein secondary structure, lipid chain conformational order, and distribution of disulfide cross-links in hair protein are presented in this study. Factor analysis of the image plane acquired with IR microscopy in hair sections, permits delineation of specific micro-regions within the hair. These data indicate that both IR and Raman imaging of molecular structural changes in a specific region of hair will prove to be valuable tools in the understanding of hair structure, physiology, and the effect of various stresses upon its integrity.

  17. Development and comparative assessment of Raman spectroscopic classification algorithms for lesion discrimination in stereotactic breast biopsies with microcalcifications

    Science.gov (United States)

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

    2014-01-01

    Microcalcifications are an early mammographic sign of breast cancer and a target for stereotactic breast needle biopsy. Here, we develop and compare different approaches for developing Raman classification algorithms to diagnose invasive and in situ breast cancer, fibrocystic change and fibroadenoma that can be associated with microcalcifications. In this study, Raman spectra were acquired from tissue cores obtained from fresh breast biopsies and analyzed using a constituent-based breast model. Diagnostic algorithms based on the breast model fit coefficients were devised using logistic regression, C4.5 decision tree classification, k-nearest neighbor (k-NN) and support vector machine (SVM) analysis, and subjected to leave-one-out cross validation. The best performing algorithm was based on SVM analysis (with radial basis function), which yielded a positive predictive value of 100% and negative predictive value of 96% for cancer diagnosis. Importantly, these results demonstrate that Raman spectroscopy provides adequate diagnostic information for lesion discrimination even in the presence of microcalcifications, which to the best of our knowledge has not been previously reported. Raman spectroscopy and multivariate classification provide accurate discrimination among lesions in stereotactic breast biopsies, irrespective of microcalcification status. PMID:22815240

  18. Surface-enhanced Raman spectroscopic study of DNA and 6-mercapto-1-hexanol interactions using large area mapping

    DEFF Research Database (Denmark)

    Frøhling, Kasper Bayer; Alstrøm, Tommy Sonne; Bache, Michael;

    2016-01-01

    intensities and peak positions it is possible to directly inspect the interplay between DNA and 6-mercapto-1-hexanol on gold covered nanopillars. It is demonstrated that optimised functionalization parameters can be extracted from the Raman spectra directly. Using the peak-fitting approach it is possible...

  19. Flow cytometric and near-infrared Raman spectroscopic investigation of quality in stained, sorted, and frozen-thawed buffalo sperm.

    Science.gov (United States)

    Li, Xiao-Xia; Wang, Meng; Chen, Huan-Hua; Li, Qing-Yang; Yang, Huan; Xu, Hui-Yan; Lu, Yang-Qing; Zhang, Ming; Yang, Xiao-Gan; Lu, Sheng-Sheng; Lu, Ke-Huan

    2016-07-01

    Flow cytometry and Laser Tweezers Raman spectroscopy have been used to investigate Nili-Ravi buffalo (Bubalus bubalis) sperm from different samples (fresh, stained, sorted and frozen-thawed) of the flow-sorting process to optimize sperm sex sorting procedures. During the sorting and freezing-thawing processes, the two detection methods both indicated there were differences in mitochondrial activity and membrane integrity. Moreover, a dispersive-type NIR (Near Infrared Reflection) use of the Raman system resulted in the ability to detect a variety of sperm components, including relative DNA, lipid, carbohydrates and protein contents. The use of the Raman system allowed for PCA (principal components analysis) and DFA (discriminant function analysis) of fresh, stained, sorted and frozen-thawed sperm. The methodology, therefore, allows for distinguishing sperm from different samples (fresh, stained, sorted and frozen-thawed), and demonstrated the great discriminative power of ANN (artificial neural network) classification models for the differentiating sperm from different phases of the flow-sorting process. In conclusion, the damage induced by sperm sorting and freezing-thawing procedures can be quantified, and in the present research it is demonstrated that Raman spectroscopy is a valuable technology for assessing sperm quality. PMID:27095613

  20. Surface-enhanced Raman spectroscopic studies of the Au-pentacene interface: A combined experimental and theoretical investigation

    Science.gov (United States)

    Adil, D.; Guha, S.

    2013-07-01

    It has recently been shown [D. Adil and S. Guha, J. Phys. Chem. C 116, 12779 (2012)], 10.1021/jp3031804 that a large enhancement in the Raman intensity due to surface-enhanced Raman scattering (SERS) is observed from pentacene when probed through the Au contact in organic field-effect transistors (OFET) structures. Here, the SERS spectrum is shown to exhibit a high sensitivity to disorder introduced in the pentacene film by Au atoms. The Raman signature of the metal-semiconductor interface in pentacene OFETs is calculated with density-functional theory by explicitly considering the Au-pentacene interaction. The observed enhancement in the 1380 cm-1 and the 1560 cm-1 regions of the experimental Raman spectrum of pentacene is successfully modeled by Au-pentacene complexes, giving insights into the nature of disorder in the pentacene sp2 network. Finally, we extend our previous work on high-operating voltage pentacene OFETs to low-operating voltage pentacene OFETs. No changes in the SERS spectra before and after subjecting the OFETs to a bias stress are observed, concurrent with no degradation in the threshold voltage. This shows that bias stress induced performance degradation is, in part, caused by field-induced structural changes in the pentacene molecule. Thus, we confirm that the SERS spectrum can be used as a visualization tool for correlating transport properties to structural changes, if any, in organic semiconductor based devices.

  1. Raman Spectroscopic Analysis of Biochemical Changes in Individual Triglyceride-Rich Lipoproteins in the Pre- and Postprandial State

    Energy Technology Data Exchange (ETDEWEB)

    Chan, J; Motton, D; Rutledge, J; Keim, N; Huser, T

    2004-09-13

    Individual triglyceride-rich lipoprotein (TGRL) particles derived from human volunteers are non-destructively analyzed by laser tweezers Raman microspectroscopy and information on their composition and distribution is obtained. The Raman signature of single optically trapped very low-density lipoproteins (VLDL), a subclass of TGRL, which play an important role in cardiovascular disease, exhibits distinct peaks associated with molecular vibrations of fatty acids, proteins, lipids, and structural rearrangements of lipids. Our analysis of pre- and postprandial VLDL exhibits the signature of biochemical changes in individual lipoprotein particles following the consumption of meals. Interaction of VLDL with endothelium leads to the breakdown of complex triacylglycerols and the formation of a highly ordered core of free saturated fatty acids in the particle. A particle distribution analysis reveals trends in the degree to which this process has occurred in particles at different times during the postprandial period. Differences in particle distributions based on the different ratios of polyunsaturated to saturated fats in the consumed meals are also easily discerned. Individual lipoprotein particles hydrolyzed in-vitro through addition of lipoprotein lipase (LpL) exhibit strikingly similar changes in their Raman spectra. These results demonstrate the feasibility of monitoring the dynamics of lipid metabolism of individual TGRL particles as they interact with LpL in the endothelial cell wall using Raman spectroscopy.

  2. Decomposition of the lanthanum hafnate pyrochlores at high pressure: x-ray diffraction and Raman spectroscopic study

    International Nuclear Information System (INIS)

    High pressure Raman and x-ray diffraction studies on lanthanum hafnate upto pressures of 65 GPa and 30 GPa indicate that beyond 10 GPa it starts disassociating into its high pressure oxides and this process is complete only beyond 30 GPa. These oxides were found to become structurally disordered at 65 GPa. (author)

  3. Iodine-benzene complex as a candidate for a real-time control of a bimolecular reaction. Spectroscopic studies of the properties of the 1:1 complex isolated in solid krypton.

    Science.gov (United States)

    Kiviniemi, Tiina; Hulkko, Eero; Kiljunen, Toni; Pettersson, Mika

    2009-06-01

    The properties of the 1:1 iodine-benzene complex isolated in a solid Kr matrix at low temperatures have been studied using UV-vis absorption, FTIR, resonance Raman, and femtosecond coherent anti-Stokes Raman spectroscopy (fs-CARS). The use of all these techniques on similar samples provides a wide view on the spectroscopic properties of the complex and allows comparison and combination of the results from different methods. The results for the complex cover its structure, the changes in the iodine molecule's vibrational frequencies and electronic absorption spectrum upon complexation, and the dynamics of the complexed I(2) molecule on both ground and excited electronic states. In addition, polarization beats between uncomplexed benzene and iodine molecules are detected in the fs-CARS spectra, showing an amplification of an electronically nonresonant CARS signal by the resonant iodine signal. The possibility of controlling the charge-transfer reaction of the I(2)-Bz complex using the excitation of a well-defined ground-state vibrational wavepacket, according to the Tannor-Rice-Kosloff scheme, is discussed on the basis of the experimental findings. PMID:19425545

  4. Structure analysis and spectroscopic characterization of 2-Fluoro-3-Methylpyridine-5-Boronic Acid with experimental (FT-IR, Raman, NMR and XRD) techniques and quantum chemical calculations

    Science.gov (United States)

    Alver, Özgür; Dikmen, Gökhan

    2016-03-01

    Possible stable conformers, geometrical molecular structures, vibrational properties as well as band assignments, nuclear magnetic shielding tensors of 2-Fluoro-3-Methylpyridine-5-Boronic Acid (2F3MP5BA) were studied experimentally and theoretically using FT-IR, Raman, (CP/MAS) NMR and XRD spectroscopic methods. FT-IR and Raman spectra were evaluated in the region of 3500-400 cm-1, and 3200-400 cm-1, respectively. The optimized geometric structures, vibrational wavenumbers and nuclear magnetic shielding tensors were examined using Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. 1H, 13C NMR chemical shifts were calculated using the gauge invariant atomic orbital (GIAO) method. 1H, 13C, APT and HETCOR NMR experiments of title molecule were carried out in DMSO solution. 13C CP/MAS NMR measurement was done with 4 mm zirconium rotor and glycine was used as an external standard. Single crystal of 2F3MP5BA was also prepared for XRD measurements. Assignments of vibrational wavenumbers were also strengthened by calculating the total energy distribution (TED) values using scaled quantum mechanical (SQM) method.

  5. FT-Raman and FT-IR vibrational spectroscopic studies of Sr{sub 2}RESbO{sub 6} (RE = La to Lu and Y) double perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez-Martinez, F.; Montero, J.L.; Carrillo, I. [Departamento de Quimica Industrial y Polimeros, EUITI, Universidad Politecnica de Madrid, 28012 Madrid (Spain); Colon, C., E-mail: cristobal.colon@upm.es [Departamento Fisica Aplicada, EUITI, Universidad Politecnica de Madrid, 28012 Madrid (Spain)

    2012-10-15

    Highlights: Black-Right-Pointing-Pointer 14 double perovskites Sr{sub 2}RESbO{sub 6} were synthesized. Black-Right-Pointing-Pointer Crystal lattice parameters have been obtained. Black-Right-Pointing-Pointer IR and Raman spectra have been obtained. Black-Right-Pointing-Pointer The crystal structure has been studied. - Abstract: The Sr{sub 2}RESbO{sub 6} double perovskites (RE = La to Lu and Y) were synthesized by ceramic method. The structure and phase purity of the prepared double perovskites were examined by X-ray diffraction pattern and vibrational spectroscopy. A systematic analysis of the compounds structure was carried out for the first time by Raman and IR spectroscopies. A simple inspection of the diffraction patterns shows that these compounds have lower symmetry than the cubic which can be usually found in the Ba{sub 2}RESbO{sub 6} double perovskites. The four active modes (A{sub 1g}, E{sub g}, and two T{sub 2g}) in the Raman spectra and the active mode (T{sub 1u}) in the IR spectra previously described in the spectroscopic data of Ba compounds have changed. In the Sr compounds these modes have been split into its components, in some cases, being active in both types of spectra. According to our data the Sr{sub 2}RESbO{sub 6} double perovskites can be described by a monoclinic symmetry cell, space group P2{sub 1}/n. However, in the cases of Sr{sub 2}LaSbO{sub 6} and Sr{sub 2}PrSbO{sub 6} an alternative structure should be searched by neutron diffraction technique.

  6. FT-IR, FT-Raman spectroscopic study of carotenoids from saffron ( Crocus sativus L.) and some derivatives

    Science.gov (United States)

    Tarantilis, Petros A.; Beljebbar, Abdelilah; Manfait, Michel; Polissiou, Moschos

    1998-04-01

    The carotenoids of saffron, crocins (CRCs), were extracted and their derivatives, dimethylcrocetin (DMCRT) and crocetin (CRT) were prepared from the extract by alkaline hydrolysis in methanol (DMCRT) and by alkaline hydrolysis in water followed by acidification (CRT), respectively. FT-IR, FT-Raman spectroscopies were used to study these compounds. The FT-IR spectra of CRCs, DMCRT and CRT have characteristic absorbance bands between 1706 and 1664 cm -1 ( νCO) and in the region between 1243 and 1228 cm -1 ( νC-O). Two main Raman lines were observed near 1540 and 1166 cm -1 which are respectively assigned to ( νCC) and ( νC-C) stretching modes.

  7. Raman spectroscopic investigation of graphitization of diamond during spark plasma sintering of UO2-diamond composite nuclear fuel

    Science.gov (United States)

    Chen, Zhichao; Subhash, Ghatu; Tulenko, James S.

    2016-07-01

    Micro-Raman spectroscopy (MRS) was utilized to investigate the graphitization of diamond particles within a UO2-diamond composite processed by spark plasma sintering (SPS). While pure diamond gives a sharp Raman peak at 1331.6 cm-1, the graphitized diamond shows broad peaks either at 1350 cm-1 (G-peak) or 1580 cm-1 (D-peak). The degree of graphitization was quantified by calculating the area beneath the diamond and graphite peaks. It was found that more than 20% of diamond was graphitized on the surface of the UO2-diamond pellet and only around 10% diamond was graphitized in the interior regions of the pellet. This current study highlights the necessity to review the implications of these results carefully while implementing UO2-diamond composite nuclear fuel.

  8. Density functional theory, restricted Hartree - Fock simulations and FTIR, FT-Raman and UV-Vis spectroscopic studies on lamotrigine

    Science.gov (United States)

    Ramya, T.; Gunasekaran, S.; Ramkumaar, G. R.

    2013-10-01

    The Fourier Transform Infrared (FTIR) and FT Raman spectra of lamotrigine have been recorded in the region 4000-450 cm-1 and 4000-50 cm-1, respectively. The title compound is used as Antiepileptic drug. The optimized geometry, frequency, and intensities of the vibrational bands of the lamotrigine were obtained by Density Functional Theory (DFT) using B3LYP/631G** basis set and ab initio method at the restricted Hartree Fock/6-31** level. The harmonic vibrational frequencies, Natural population analysis, HOMO-LUMO energy gap, infra red intensities and Raman scattering activities, force constant were calculated by DFT and RHF methods. The quality of lamotrigine under different storage containers were analyzed using UV-Vis spectral technique.

  9. Raman spectroscopic evidence of low temperature stability of D,L-glycolic and L-(+)-lactic acid crystals.

    Science.gov (United States)

    Mohaček-Grošev, Vlasta; Šoštarić, Vladimir; Maksimović, Aleksandar

    2015-04-01

    Raman and infrared spectra of polycrystalline D,L-glycolic and L-(+) lactic acid are presented and assigned both by an ab initio calculation of normal modes of free conformers and by self-consistent-charge density-functional-theory computational program DFTB+. Temperature dependent Raman spectra from 295 K to 10 K reveal great stability of crystal lattices, since no soft modes and no band splittings that could be attributed to changes of the number of molecules per unit cell were observed. A semiempirical calculation with GULP program was used to estimate the strength of hydrogen bonds in crystals: in glycolic acid they have energies of -0.337 eV/mol, -0.329 eV/mol, -0.262 eV/mol and -0.242 eV/mol, while in lactic acid two hydrogen bonds have energies of -0.283 eV/mol and -0.202 eV/mol.

  10. 1550 nm superluminescent diode and anti-Stokes effect CCD camera based optical coherence tomography for full-field optical metrology

    Science.gov (United States)

    Kredzinski, Lukasz; Connelly, Michael J.

    2011-06-01

    Optical Coherence Tomography (OCT) is a promising non-invasive imaging technology capable of carrying out 3D high-resolution cross-sectional images of the internal microstructure of examined material. However, almost all of these systems are expensive, requiring the use of complex optical setups, expensive light sources and complicated scanning of the sample under test. In addition most of these systems have not taken advantage of the competitively priced optical components available at wavelength within the main optical communications band located in the 1550 nm region. A comparatively simple and inexpensive full-field OCT system (FF-OCT), based on a superluminescent diode (SLD) light source and anti-stokes imaging device was constructed, to perform 3D cross-sectional imaging. This kind of inexpensive setup with moderate resolution could be easily applicable in low-level biomedical and industrial diagnostics. This paper involves calibration of the system and determines its suitability for imaging structures of biological tissues such as teeth, which has low absorption at 1550 nm.

  11. Development and comparative assessment of Raman spectroscopic classification algorithms for lesion discrimination in stereotactic breast biopsies with microcalcifications.

    Science.gov (United States)

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

    2013-04-01

    Microcalcifications are an early mammographic sign of breast cancer and a target for stereotactic breast needle biopsy. Here, we develop and compare different approaches for developing Raman classification algorithms to diagnose invasive and in situ breast cancer, fibrocystic change and fibroadenoma that can be associated with microcalcifications. In this study, Raman spectra were acquired from tissue cores obtained from fresh breast biopsies and analyzed using a constituent-based breast model. Diagnostic algorithms based on the breast model fit coefficients were devised using logistic regression, C4.5 decision tree classification, k-nearest neighbor (k -NN) and support vector machine (SVM) analysis, and subjected to leave-one-out cross validation. The best performing algorithm was based on SVM analysis (with radial basis function), which yielded a positive predictive value of 100% and negative predictive value of 96% for cancer diagnosis. Importantly, these results demonstrate that Raman spectroscopy provides adequate diagnostic information for lesion discrimination even in the presence of microcalcifications, which to the best of our knowledge has not been previously reported. PMID:22815240

  12. Raman Cooling of Solids through Photonic Density of States Engineering

    CERN Document Server

    Chen, Yin-Chung

    2015-01-01

    The laser cooling of vibrational states of solids has been achieved through photoluminescence in rare-earth elements, optical forces in optomechanics, and the Brillouin scattering light-sound interaction. The net cooling of solids through spontaneous Raman scattering, and laser refrigeration of indirect band gap semiconductors, both remain unsolved challenges. Here, we analytically show that photonic density of states (DoS) engineering can address the two fundamental requirements for achieving spontaneous Raman cooling: suppressing the dominance of Stokes (heating) transitions, and the enhancement of anti-Stokes (cooling) efficiency beyond the natural optical absorption of the material. We develop a general model for the DoS modification to spontaneous Raman scattering probabilities, and elucidate the necessary and minimum condition required for achieving net Raman cooling. With a suitably engineered DoS, we establish the enticing possibility of refrigeration of intrinsic silicon by annihilating phonons from ...

  13. Raman crystal lasers in the visible and near-infrared

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Raman lasers based on potassium gadolinium tungstate and lead tungstate crystals pumped by a≈120 ps Nd: YAG laser at 1.064 μm were developed. High reflection mirrors for the Stokes wavelength have been used to generate near-infrared and eye safe spectral region of 1.15-1.32 μm. Second harmonic generation of the generated Raman lasers was observed. Eifficient multiple Stokes and anti-Stokes picosecond generation in 64 crystals have been shown to exhibit stimulated Raman scattering on about 700 lines covering the whole visible and near-infrared spectrum. All stimulated Raman scattering (SRS) wavelengths in the visible and near-infrared spectrum are identified and attributed to the SRS-active vibration modes of these crystals.

  14. Raman crystal lasers in the visible and near-infrared

    Institute of Scientific and Technical Information of China (English)

    EICHLERH.J.; GADG.M.A.; KAMINSKIIA.A.; RHEEH.

    2003-01-01

    Raman lasers based on potassium gadolinium tungstate and lead tungstate crystals pumped by a≈120 ps Nd: YAG laser at 1.064/μm were developed. High reflection mirrors for the Stokes wavelength have been used to generate near-infrared and eye safe spectral region of 1.15 - 1.32/μm. Second harmonic generation of the generated Raman lasers was observed. Eifficient multiple Stokes and anti-Stokes picosecond generation in 64 crystals have been shown to exhibit stimulated Raman scattering on about 700 lines covering the whole visible and near-infrared spectrum. All stimulated Raman scattering (SRS) wavelengths in the visible and near-infrared spectrum are identified and attributed to the SRS-active vibration modes of these crystals.

  15. Structure, Raman and infrared spectroscopic properties of new nonlinear optical material Na3VO2B6O11

    Science.gov (United States)

    Zhang, Ji; Dou, Renqin; Zhang, Deming; Zhang, Qingli; Yin, Shaotang

    2016-08-01

    In this paper we report on the structure of Na3VO2B6O11 (NVBO) single crystals which were investigated by XRD, polarized Raman spectra in the range from 10 to 1600 cm-1 and infrared spectrum (IR) in the range from 100 to 1600 cm-1. Factor group analysis has been used to study the full vibrational representation of the crystal. More than 120 phonon modes have been obtained, which are related to Bsbnd O and Vsbnd O vibration in the trigonal planar BO3 triangle groups and tetrahedral BO4/VO4 groups. The high frequency bands located at 1300-1415 cm-1 are assigned to stretching modes of the trigonal planar BO3 groups. Moreover, intense Raman modes located at 631 cm-1 is related to BO3 bending vibration as well. The weak band at 1158 cm-1 (A1 mode) and strong band at 431 cm-1 (A1 mode) are attributed to asymmetric stretching and bending vibration mode of tetrahedral BO4 groups respectively. The vibrational band at 765-738 cm-1 in the Raman spectra of NVBO crystal maybe related to the breathing vibration of the boroxol ring consisting of two BO4 tetrahedra. In addition, we assigned the intense band 900 (A1 mode) and 831 cm-1 (B2 mode) are relative to the v1 symmetric stretching vibration of VO4 tetrahedra. And the middle intense band at 382 (A1 mode) and 385 (A2 mode) are due to Osbnd Vsbnd O vibration in VO4 tetrahedra.

  16. Raman spectroscopic studies on the structural changes of poly(3-methylthiophene)during heating and cooling processes

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Poly(3-methylthiophene) (PMeT) electrosynthesized by direct oxidation of 3-methylthiophene in boron trifluoride diethyl etherate (BFEE) has been studied by Raman spectroscopy in the temperature scale of 123-458 K. Experimental results demonstrate that the thermal stability of PMeT in the oxidized state is much lower than that of the polymer in the neutral state. Furthermore, during the cooling process, the conformation of neutral species changes from a coil-like state into a rod-like state, while the conformation of the oxidized species does not change.

  17. Generation of a VUV-to-visible Raman frequency comb in hydrogen-filled kagom\\'e photonic crystal fiber

    CERN Document Server

    Mridha, M K; Bauerschmidt, S T; Abdolvand, A; Russell, P St J

    2016-01-01

    We report the generation of a purely vibrational Raman comb, extending from the vacuum ultraviolet (184 nm) to the visible (478 nm), in hydrogen-filled kagom\\'e-style photonic crystal fiber pumped at 266 nm. Stimulated Raman scattering and molecular modulation processes are enhanced by higher Raman gain in the ultraviolet. Owing to the pressure-tunable normal dispersion landscape of the fiber-gas system in the ultraviolet, higher-order anti-Stokes bands are generated preferentially in higher-order fiber modes. The results pave the way towards tunable fiber-based sources of deep- and vacuum ultraviolet light for applications in, e.g., spectroscopy and biomedicine.

  18. Elemental analysis-aided Raman spectroscopic studies on Chinese cloisonné wares and painted enamels from the Imperial Palace

    Science.gov (United States)

    Su, Yan; Qu, Liang; Duan, Hongying; Tarcea, Nicolae; Shen, Aiguo; Popp, Jürgen; Hu, Jiming

    2016-01-01

    Two kinds of enamels, including Chinese cloisonné wares from Fuwang chamber and gourd-shaped painted enamels decorations from the Forbidden City, in the Imperial Palace of China, are investigated by micro-Raman spectroscopy in combination with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and energy-dispersive X-ray fluorescence (EDXRF) in order to examine and analyze the composition of the glaze layer in each case. In this study the excitation is employed with either a NIR laser (785 nm) or a red laser (632.8 nm) in order to effectively eliminate the interference of background fluorescence and resonance effect. We have identified that the major matrix ingredients of the cloisonné wares are lead-based potash-lime silicate glasses while lead-potash silicate glass matrix is the main constituent for the painted enamels. Eight different colored areas of glaze layer also have been discussed in detail due to the distinct colors including turquoise, deep blue, yellow, white, red, pink, deep green and pale green. Their identification based on Raman data will be useful with regard to rapid and on site analysis and the restoration of the enamel decorations.

  19. NMR, FT-IR, Raman and UV-Vis spectroscopic investigation and DFT study of 6-Bromo-3-Pyridinyl Boronic Acid

    Science.gov (United States)

    Dikmen, Gökhan; Alver, Özgür

    2015-11-01

    Possible stable conformers and geometrical molecular structures of 6-Bromo-3-Pyridinyl Boronic acid (6B3PBA; C5H5BBrNO2) were studied experimentally and theoretically using FT-IR and Raman spectroscopic methods. FT-IR and Raman spectra were recorded in the region of 4000-400 cm-1 and 3700-400 cm-1, respectively. The structural properties were investigated further, using 1H, 13C, 1H coupled 13C, HETCOR, COSY and APT NMR techniques. The optimized geometric structures were searched by Becke-3-Lee-Yang-Parr (B3LYP) hybrid density functional theory method with 6-311++G(d, p) basis set. Vibrational wavenumbers of 6B3PBA were calculated whereby B3LYP density functional methods including 6-311++G(d, p), 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. The comparison of the experimentally and theoretically obtained results using mean absolute error and experimental versus calculated correlation coefficients for the vibrational wavenumbers indicates that B3LYP method with 6-311++G(d, p) gives more satisfactory results for predicting vibrational wavenumbers when compared to the 6-311G(d, p), 6-311G(d), 6-31G(d, p) and 6-31G(d) basis sets. However, this method and none of the mentioned methods here seem suitable for the calculations of OH stretching modes, most likely because increasing unharmonicity in the high wave number region and possible intra and inter molecular interactions at OH edges lead some deviations between experimental and theoretical results. Moreover, reliable vibrational assignments were made on the basis of total energy distribution (TED) calculated using scaled quantum mechanical (SQM) method.

  20. Spectroscopic [FT-IR and FT-Raman] and molecular modeling (MM) study of benzene sulfonamide molecule using quantum chemical calculations

    Science.gov (United States)

    Vinod, K. S.; Periandy, S.; Govindarajan, M.

    2016-07-01

    The spectroscopic and molecular modeling (MM) study includes, FT-IR, FT-Raman and 13C NMR and 1H NMR spectra of the Benzene sulfonamide were recorded for the analysis. The observed experimental and theoretical frequencies (IR and Raman) were assigned according to their distinctive region. The present study of this title molecule have been carried out by hybrid computational calculations of HF and DFT (B3LYP) methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets and the corresponding results are tabulated. The structural modifications of the compound due to the substitutions of NH2 and SO2 were investigated. The minimum energy conformers of the compound were studied using conformational analysis. The alternations of the vibrational pattern of the base structure related to the substitutions were analyzed. The thermodynamic parameters (such as zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment) of Benzene sulfonamide have been calculated. The donor acceptor interactions of the compound and the corresponding UV transitions are found out using NBO analysis. The NMR spectra were simulated by using the gauge independent atomic orbital (GIAO) method with B3LYP methods and the 6-311++G(d,p) basis set and their spectra were simulated and the chemical shifts related to TMS were compared. A quantum computational study on the electronic and optical properties absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, were performed by HF and DFT methods. The energy gap of the present compound was calculated related to HOMO and LUMO energies which confirm the occurring of charge transformation between the base and ligand group. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures were calculated in gas phase and

  1. Spectroscopic (UV/VIS, Raman) and Electrophoresis Study of Cytosine-Guanine Oligonucleotide DNA Influenced by Magnetic Field.

    Science.gov (United States)

    Banihashemian, Seyedeh Maryam; Periasamy, Vengadesh; Boon Tong, Goh; Abdul Rahman, Saadah

    2016-01-01

    Studying the effect of a magnetic field on oligonucleotide DNA can provide a novel DNA manipulation technique for potential application in bioengineering and medicine. In this work, the optical and electrochemical response of a 100 bases oligonucleotides DNA, cytosine-guanine (CG100), is investigated via exposure to different magnetic fields (250, 500, 750, and 1000 mT). As a result of the optical response of CG100 to the magnetic field, the ultra-violet-visible spectrum indicated a slight variation in the band gap of CG100 of about 0.3 eV. Raman spectroscopy showed a significant deviation in hydrogen and phosphate bonds' vibration after exposure to the magnetic field. Oligonucleotide DNA mobility was investigated in the external electric field using the gel electrophoresis technique, which revealed a small decrease in the migration of CG100 after exposure to the magnetic field.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-12-01

    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).

  3. Quantum Mechanical Description of Raman Scattering from Molecules in Plasmonic Cavities.

    Science.gov (United States)

    Schmidt, Mikolaj K; Esteban, Ruben; González-Tudela, Alejandro; Giedke, Geza; Aizpurua, Javier

    2016-06-28

    Plasmon-enhanced Raman scattering can push single-molecule vibrational spectroscopy beyond a regime addressable by classical electrodynamics. We employ a quantum electrodynamics (QED) description of the coherent interaction of plasmons and molecular vibrations that reveal the emergence of nonlinearities in the inelastic response of the system. For realistic situations, we predict the onset of phonon-stimulated Raman scattering and a counterintuitive dependence of the anti-Stokes emission on the frequency of excitation. We further show that this QED framework opens a venue to analyze the correlations of photons emitted from a plasmonic cavity. PMID:27203727

  4. Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation on 1-phenyl-2-nitropropene by quantum computational calculations.

    Science.gov (United States)

    Xavier, S; Periandy, S

    2015-01-01

    In this paper, the spectral analysis of 1-phenyl-2-nitropropene is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum mechanical computations using ab-initio and density functional theories. The FT-IR (4000-400 cm(-1)) and FT-Raman (4000-100 cm(-1)) spectra were recorded in solid phase, the (1)H and (13)C NMR spectra were recorded in CDCl3 solution phase and the UV-Vis (200-800 nm) spectrum was recorded in ethanol solution phase. The different conformers of the compound and their minimum energies are studied using B3LYP functional with 6-311+G(d,p) basis set and two stable conformers with lowest energy were identified and the same was used for further computations. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the modes of vibrations are assigned and the structure the molecule is analyzed in terms of parameters like bond length, bond angle and dihedral angle predicted by both B3LYP and B3PW91 methods with 6-311+G(d,p) and 6-311++G(d,p) basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non-linear property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for (1)H and (13)C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts. NBO analysis is carried out to picture the charge transfer between the localized bonds and lone pairs. The local reactivity of the molecule has been studied using the Fukui function. The thermodynamic properties (heat capacity, entropy and enthalpy) at different temperatures are also calculated. PMID:25965169

  5. Raman spectroscopic analysis of the increase of the carotenoid antioxidant concentration in human skin after a 1-week diet with ecological eggs

    Science.gov (United States)

    Hesterberg, Karoline; Lademann, Jürgen; Patzelt, Alexa; Sterry, Wolfram; Darvin, Maxim E.

    2009-03-01

    Skin aging is mainly caused by the destructive action of free radicals, produced by the UV light of the sun. The human skin has developed a protection system against these highly reactive molecules in the form of the antioxidative potential. Carotenoids are one of the main components of the antioxidants of the human skin. From former studies, it is known that skin aging is reduced in individuals with high levels of carotenoids. Because most of the antioxidants cannot be produced by the human organism, they must be up taken by nutrition. Using noninvasive Raman spectroscopic measurements it is demonstrated that not only fruits and vegetables but also eggs contain high concentrations of antioxidants including carotenoids, which are even doubled in the case of ecological eggs. After a 1-week diet with ecological eggs performed by six volunteers, it is found that the concentration of the carotenoids in the skin of the volunteers increased by approx. 20%. Our study does not intend to recommend exorbitant egg consumption, as eggs also contain harmful cholesterol. But in the case of egg consumption, ecological eggs from hens kept on pasture should be preferred to also receive a benefit for the skin.

  6. Biomolecular interaction study of hydralazine with bovine serum albumin and effect of β-cyclodextrin on binding by fluorescence, 3D, synchronous, CD, and Raman spectroscopic methods.

    Science.gov (United States)

    Bolattin, Mallavva B; Nandibewoor, Sharanappa T; Chimatadar, Shivamurti A

    2016-07-01

    Spectrofluoremetric technique was employed to study the binding behavior of hydralazine with bovine serum albumin (BSA) at different temperatures. Binding study of bovine serum albumin with hydralazine has been studied by ultraviolet-visible spectroscopy, fluorescence spectroscopy and confirmed by three-dimensional, synchronous, circular dichroism, and Raman spectroscopic methods. Effect of β-cyclodextrin on binding was studied. The experimental results showed a static quenching mechanism in the interaction of hydralazine with bovine serum albumin. The binding constant and the number of binding sites are calculated according to Stern-Volmer equation. The thermodynamic parameters ∆H(o) , ∆G(o) , ∆S(o) at different temperatures were calculated. These indicated that the hydrogen bonding and weak van der Waals forces played an important role in the interaction. Based on the Förster's theory of non-radiation energy transfer, the binding average distance, r, between the donor (BSA) and acceptor (hydralazine) was evaluated and found to be 3.95 nm. Spectral results showed that the binding of hydralazine to BSA induced conformational changes in BSA. The effect of common ions on the binding of hydralazine to BSA was also examined. Copyright © 2016 John Wiley & Sons, Ltd.

  7. FT-IR and FT-Raman, NMR and UV spectroscopic investigation and hybrid computational (HF and DFT) analysis on the molecular structure of mesitylene

    Science.gov (United States)

    Kose, E.; Atac, A.; Karabacak, M.; Nagabalasubramanian, P. B.; Asiri, A. M.; Periandy, S.

    2013-12-01

    The spectroscopic properties of mesitylene were investigated by FT-IR, FT-Raman, UV, 1H and 13C NMR techniques. The geometrical parameters and energies have been obtained from density functional theory (DFT) B3LYP method and Hartree-Fock (HF) method with 6-311++G(d,p) and 6-311G(d,p) basis sets calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. 13C and 1H NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. Reduced density gradient (RDG) of the mesitylene was also given to investigate interactions of the molecule.

  8. Spectroscopic characteristic (FT-IR, FT-Raman, UV, 1H and 13C NMR), theoretical calculations and biological activity of alkali metal homovanillates

    Science.gov (United States)

    Samsonowicz, M.; Kowczyk-Sadowy, M.; Piekut, J.; Regulska, E.; Lewandowski, W.

    2016-04-01

    The structural and vibrational properties of lithium, sodium, potassium, rubidium and cesium homovanillates were investigated in this paper. Supplementary molecular spectroscopic methods such as: FT-IR, FT-Raman in the solid phase, UV and NMR were applied. The geometrical parameters and energies were obtained from density functional theory (DFT) B3LYP method with 6-311++G** basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned. Geometric and magnetic aromaticity indices, atomic charges, dipole moments, HOMO and LUMO energies were also calculated. The microbial activity of investigated compounds was tested against Bacillus subtilis (BS), Pseudomonas aeruginosa (PA), Escherichia coli (EC), Staphylococcus aureus (SA) and Candida albicans (CA). The relationship between the molecular structure of tested compounds and their antimicrobial activity was studied. The principal component analysis (PCA) was applied in order to attempt to distinguish the biological activities of these compounds according to selected band wavenumbers. Obtained data show that the FT-IR spectra can be a rapid and reliable analytical tool and a good source of information for the quantitative analysis of the relationship between the molecular structure of the compound and its biological activity.

  9. FT-Raman spectroscopic study of skin wound healing in diabetic rats treated with Cenostigma macrophyllum Tul

    International Nuclear Information System (INIS)

    Introduction: patients with diabetes mellitus exhibit a delay in the lesion repair process. The active components of Cenostigma macrophyllum may represent a viable alternative to facilitate the recovery of these lesions. The aim of this study was to evaluate the effects of emulsion oil-water Cenostigma macrophyllum in the repair process of lesions in rats with induced diabetes. Methods: 63 male rats (Wistar, 200-250 g body weight, 30-40 days old) were distributed into the following groups: control (C), diabetic (D) and diabetic treated with Cenostigma macrophyllum (P), subdivided based on the experimental times, days 7, 14 and 28, with 21 animals per main group. Diabetes mellitus (DM) was induced by administration of streptozotocin (50 mg/kg via penile vein and 12-h fasting) and confirmed at day 21 (glycemic index > 240 mg/dL). In the animals of group P, 0.5 ml of the oil-water emulsion obtained from the plant seed was used. The samples were removed and hemisectioned, and one portion was used for the quantitative histological analysis of collagen using Masson's trichrome staining, while another portion was analyzed by FT-Raman spectroscopy. Results: A higher percentage area of the volume of collagen fibers was observed for the experimental time Day 14 in group P compared with group D (p -1) and III (1245-1345 cm-1), the groups D and P show the opposite behavior. Conclusion: Cenostigma macrophyllum accelerated the repair process in skin of diabetic ratsfor14 days. (author)

  10. Raman spectroscopic method for the determination of medroxyprogesterone acetate in a pharmaceutical suspension: validation of quantifying abilities, uncertainty assessment and comparison with the high performance liquid chromatography reference method.

    Science.gov (United States)

    De Beer, T R M; Baeyens, W R G; Vermeire, A; Broes, D; Remon, J P; Vervaet, C

    2007-04-25

    An alternative fast and non-destructive validated Raman spectroscopic analytical procedure, requiring no sample preparation, was compared with the industrially applied HPLC reference method (Pfizer Manufacturing Belgium) for the quantitative determination of medroxyprogesterone acetate (MPA) in DepoProvera suspensions (150 mg mL(-1), Pfizer). The Raman calibration model was developed by plotting the peak intensity of the baseline-corrected and normalized spectral band (corrected by external standard measurements) between 1595 and 1620 cm(-1) against known MPA concentrations in standards. At this band, no spectral interferences from the suspension medium are observed. The most suitable model for the calibration data (straight line or higher order polynomial) was determined by evaluating the fit and predictive properties of the models. In a second step, the developed Raman spectroscopic analytical method was validated by calculating the accuracy profile on the basis of the analysis results of validation samples. Furthermore, based on the data of the accuracy profile, the measurement uncertainty was determined. Finally, as the aim of the alternative method is to replace the destructive, time-consuming HPLC method, requiring sample preparation, it needs to be demonstrated that the new Raman method performs at least as good as the HPLC method. Therefore, the performance (precision and bias) of both methods was compared. A second order polynomial calibration curve through the calibration data supplies the best predictive properties and gives an acceptable fit. From the accuracy profile, it was concluded that at the target concentration (150 mg mL(-1)), 95 out 100 future routine measurements will be included within the acceptance limits (5%). Comparison of the alternative method with the reference method at the target concentration indicates that the Raman method performs at least as good as the HPLC method for precision (repeatability and intermediate precision) and bias

  11. Coherent Raman spectro-imaging with laser frequency combs

    CERN Document Server

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

    2013-01-01

    Optical spectroscopy and imaging of microscopic samples have opened up a wide range of applications throughout the physical, chemical, and biological sciences. High chemical specificity may be achieved by directly interrogating the fundamental or low-lying vibrational energy levels of the compound molecules. Amongst the available prevailing label-free techniques, coherent Raman scattering has the distinguishing features of high spatial resolution down to 200 nm and three-dimensional sectioning. However, combining fast imaging speed and identification of multiple - and possibly unexpected- compounds remains challenging: existing high spectral resolution schemes require long measurement times to achieve broad spectral spans. Here we overcome this difficulty and introduce a novel concept of coherent anti-Stokes Raman scattering (CARS) spectro-imaging with two laser frequency combs. We illustrate the power of our technique with high resolution (4 cm-1) Raman spectra spanning more than 1200 cm-1 recorded within le...

  12. Cavity-Enhanced Room-Temperature Broadband Raman Memory

    Science.gov (United States)

    Saunders, D. J.; Munns, J. H. D.; Champion, T. F. M.; Qiu, C.; Kaczmarek, K. T.; Poem, E.; Ledingham, P. M.; Walmsley, I. A.; Nunn, J.

    2016-03-01

    Broadband quantum memories hold great promise as multiplexing elements in future photonic quantum information protocols. Alkali-vapor Raman memories combine high-bandwidth storage, on-demand readout, and operation at room temperature without collisional fluorescence noise. However, previous implementations have required large control pulse energies and have suffered from four-wave-mixing noise. Here, we present a Raman memory where the storage interaction is enhanced by a low-finesse birefringent cavity tuned into simultaneous resonance with the signal and control fields, dramatically reducing the energy required to drive the memory. By engineering antiresonance for the anti-Stokes field, we also suppress the four-wave-mixing noise and report the lowest unconditional noise floor yet achieved in a Raman-type warm vapor memory, (15 ±2 )×10-3 photons per pulse, with a total efficiency of (9.5 ±0.5 )%.

  13. FT-Raman spectroscopic study of skin wound healing in diabetic rats treated with Cenostigma macrophyllum Tul

    Energy Technology Data Exchange (ETDEWEB)

    Coelho, Nayana Pinheiro Machado de Freitas; Martins, Marcelino, E-mail: nayanamachado@oi.com.br [Faculdade Diferencial Integral (FACID), Teresina, PI (Brazil); Costa, Charlytton Luis Sena da; Maia Filho, Antonio Luis [Universidade Estadual do Piaui (UESPI), Teresina, PI (Brazil); Raniero, Leandro; Martin, Airton Abrahao; Arisawa, Emilia Angela Loschiavo [Universidade do Vale do Paraiba (UNIVAP), Sao Jose dos Campos, SP (Brazil). Instituto de Pesquisa e Desenvolvimento

    2014-07-01

    Introduction: patients with diabetes mellitus exhibit a delay in the lesion repair process. The active components of Cenostigma macrophyllum may represent a viable alternative to facilitate the recovery of these lesions. The aim of this study was to evaluate the effects of emulsion oil-water Cenostigma macrophyllum in the repair process of lesions in rats with induced diabetes. Methods: 63 male rats (Wistar, 200-250 g body weight, 30-40 days old) were distributed into the following groups: control (C), diabetic (D) and diabetic treated with Cenostigma macrophyllum (P), subdivided based on the experimental times, days 7, 14 and 28, with 21 animals per main group. Diabetes mellitus (DM) was induced by administration of streptozotocin (50 mg/kg via penile vein and 12-h fasting) and confirmed at day 21 (glycemic index > 240 mg/dL). In the animals of group P, 0.5 ml of the oil-water emulsion obtained from the plant seed was used. The samples were removed and hemisectioned, and one portion was used for the quantitative histological analysis of collagen using Masson's trichrome staining, while another portion was analyzed by FT-Raman spectroscopy. Results: A higher percentage area of the volume of collagen fibers was observed for the experimental time Day 14 in group P compared with group D (p < 0.001). Regarding the ratio of areas of the amides I (1700-1600 cm{sup -1}) and III (1245-1345 cm{sup -1}), the groups D and P show the opposite behavior. Conclusion: Cenostigma macrophyllum accelerated the repair process in skin of diabetic ratsfor14 days. (author)

  14. A Raman Spectroscopic Study of the Structural Modifications Associated with the Addition of Calcium Oxide and Boron Oxide to Silica

    Science.gov (United States)

    Kline, Jeff; Tangstad, Merete; Tranell, Gabriella

    2015-02-01

    Raman spectroscopy as an instrumental technique for the determination of silicate structure is widely accepted. This method was utilized for analysis of structural modifications associated with the addition of network modifying species. Silicate melts are described by the extent of oxygen bridging. Therefore, understanding the effect different oxides have on modifying the silicate structure will provide valuable information regarding the removal of boron from silicon in slag refining processes. Samples in the range CaO/SiO2 = 0.56 to 1.2 were evaluated with and without varying concentrations of B2O3. As expected, increasing the CaO content resulted in an increase in the Q 0 and Q 1 species and a decrease in the Q 3 species indicating a depolymerization of the silicate network. The addition of B2O3 to the 36 wt pct CaO-64 wt pct SiO2 system resulted in a decrease in ring-typed structures associated with the vibrational mode near 600 cm-1, an increase in the Q 3 species and a decrease in the Q 2 species. Adding B2O3 to the 54.5 wt pct CaO-45.5 wt pct SiO2 system resulted in decrease in the Q 0 and Q 2 species and an increase in the Q 3 species. Thus, both systems indicate the introduction of B2O3 to the more polymerized structural units in the silicate network. The increase in the peak near 630 cm-1 signifies some formation of ring-type metaborate groups or ring-type danburite groups. A correlation between the experimentally determined Q n distribution and optical basicity is proposed. Viscosity and optical basicity are correlated for the CaO-SiO2 system as well as viscosity and.

  15. Micro-Raman spectroscopic identification of natural mineral phases and their weathering products inside an abandoned zinc/lead mine

    Science.gov (United States)

    Goienaga, N.; Arrieta, N.; Carrero, J. A.; Olivares, M.; Sarmiento, A.; Martinez-Arkarazo, I.; Fernández, L. A.; Madariaga, J. M.

    2011-10-01

    Mining activities provide a good source of minerals of different nature. On the one hand, the primary minerals for whose formation a geological time-scale is required. On the other hand, secondary minerals, formed from removed products after the earlier weathering and alteration states. These are characteristic of the local geology and the environment context that commonly appears due to the low chemical stability of their original primary minerals. This work shows how quickly the reactions promoting secondary minerals may have taken place, due to the fact that these were found in newly formed solid materials called efflorescences. To achieve this purpose, the sampling is crucial. It was carried out in such a way that tried to guarantee that the samples collected consisted in the very top soil matter (first 2 cm depth). Thus, unlike the deeper soil, the material analysed may have been newly formed due to the interactions that they had with the place weathering agents (i.e. air oxygen, humidity, and microbial activities). Raman spectroscopy has emerged as a good and fast non-destructive technique that provides molecular information of the local mineralogy without the need of any pre-treatment of the samples. At the same time, the work looked for information on the variety of non-stable lead and-or zinc containing minerals due to the possible health and environmental risks they convey. Among the different minerals identified, 16 were of primary nature while 23 may be classified as secondary minerals, probably formed in the last decades as the result of the extractive activities.

  16. Spectroscopic (infrared, Raman, UV and NMR) analysis, Gaussian hybrid computational investigation (MEP maps/HOMO and LUMO) on cyclohexanone oxime

    Science.gov (United States)

    Ramalingam, S.; Karabacak, M.; Periandy, S.; Puviarasan, N.; Tanuja, D.

    2012-10-01

    In the present analysis, FT-IR/FT-Raman spectra of the cyclohexanone oxime (CHO, C6H11NO) are recorded. The observed vibrational frequencies are assigned and the computational calculations are carried out by HF and DFT (B3LYP and B3PW91) methods with 6-311++G(d,p) basis set and the corresponding results are tabulated. In order to yield good coherence with observed values, the calculated frequencies are scaled by appropriate scale factors. The complete assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method. The alternation of structure of cyclohexanone due to the substitution of NOH is investigated. The vibrational sequence pattern of the molecule related to the substitutions is analyzed. Comparison of the observed fundamental vibrational frequencies of CHO and calculated results by density functional (B3LYP and B3PW91) and HF methods indicates that B3LYP is superior to the scaled HF and B3PW91 approach for molecular vibrational problems. Moreover, 13C NMR and 1H NMR chemical shifts are calculated by using the gauge independent atomic orbital (GIAO) method with HF/B3LYP/B3PW91 methods and the same basis set. A study on the electronic properties; absorption wavelengths, excitation energy, dipole moment and frontier molecular orbital energies, are performed by HF and DFT methods. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Besides frontier molecular orbitals (FMO), molecular electrostatic potential (MEP) was performed. NLO properties and Mulliken charges of the CHO was also calculated and interpreted. The thermodynamic properties (heat capacity, entropy, and enthalpy) of the title compound at different temperatures are calculated in gas phase.

  17. Detection of bacterial endospores by means of ultrafast coherent Raman spectroscopy

    Science.gov (United States)

    Pestov, Dmitry Sergeyevich

    This work is devoted to formulation and development of a laser spectroscopic technique for rapid detection of biohazards, such as Bacillus anthracis spores. Coherent anti-Stokes Raman scattering (CARS) is used as an underlying process for active retrieval of species-specific characteristics of an analyte. Vibrational modes of constituent molecules are Raman-excited by a pair of ultrashort, femtosecond laser pulses, and then probed through inelastic scattering of a third, time-delayed laser field. We first employ the already known time-resolved CARS technique. We apply it to the spectroscopy of easy-to-handle methanol-water mixtures, and then continue building our expertise on solutions of dipicolinic acid (DPA) and its salts, which happen to be marker molecules for bacterial spores. Various acquisition schemes are evaluated, and the preference is given to multi-channel frequency-resolved detection, when the whole CARS spectrum is recorded as a function of the probe pulse delay. We demonstrate a simple detection algorithm that manages to differentiate DPA solution from common interferents. We investigate experimentally the advantages and disadvantages of near-resonant probing of the excited molecular coherence, and finally observe the indicative backscattered CARS signal from DPA and NaDPA powders. The possibility of selective Raman excitation via pulse shaping of the preparation pulses is also demonstrated. The analysis of time-resolved CARS experiments on powders and B. subtilis spores, a harmless surrogate for B. anthracis, facilitates the formulation of a new approach, where we take full advantage of the multi-channel frequency-resolved acquisition and spectrally discriminate the Raman-resonant CARS signal from the background due to other instantaneous four-wave mixing (FWM) processes. Using narrowband probing, we decrease the magnitude of the nonresonant FWM, which is further suppressed by the timing of the laser pulses. The devised technique, referred to as

  18. Direct observation of the cyclic dimer in liquid acetic acid by probing the C=O vibration with ultrafast coherent Raman spectroscopy.

    Science.gov (United States)

    Lütgens, Matthias; Friedriszik, Frank; Lochbrunner, Stefan

    2014-09-01

    We present a comparison of spontaneous Raman and ultrafast coherent anti-Stokes Raman scattering (CARS) spectra of the C=O vibration of liquid acetic acid. The former technique cannot clearly reveal the number of contributions in the spectrum. However, the additional time and spectrally resolved CARS experiment supports strictly the existence of four modes, which proves the coexistence of more than one H-bonded configuration in liquid acetic acid. A comparably slowly dephasing mode which is obscured by a broad band in the linear Raman spectrum is assigned to the cyclic dimer and can be observed freed from all other contributions by ultrafast CARS.

  19. Reaching millikelvin resolution in Raman distributed temperature sensing using image processing

    Science.gov (United States)

    Soto, Marcelo A.; Ramírez, Jaime A.; Thévenaz, Luc

    2016-05-01

    Image processing is proposed and experimentally demonstrated to improve the capabilities of Raman distributed optical fibre sensors. The here reported technique consists in stacking consecutive one-dimensional Raman Stokes and anti-Stokes traces in two-dimensional data arrays (one for each Raman component), which are then processed by an image denoising algorithm. Owing to the high level of correlation between consecutive measurements in conventional Raman sensing, it is experimentally demonstrated that this newly-proposed two-dimensional denoising approach provides a significant signal-to-noise ratio improvement, which in this case reaches 13.6 dB with no hardware modification to the conventional set-up. Experimental results demonstrate Raman distributed sensing with a remarkably enhanced temperature resolution of 4 mK at 9 km distance, which is obtained with 2 m spatial resolution and a short acquisition time of 35 s.

  20. Spectroscopic (FT-IR, FT-Raman, UV, NMR, NBO) investigation and molecular docking study of (R)-2-Amino-1-PhenylEthanol

    Science.gov (United States)

    Subashini, K.; Periandy, S.

    2016-08-01

    A systematic spectroscopic study of (R)-2-Amino-1-Phenylethanol was carried out using FT-IR, FT-Raman, NMR and UV analysis. FT-IR (4000-400 cm-1) and FT-Raman (4000-100 cm-1) spectrum of the title molecule were recorded in solid phase, the 1H and 13C NMR spectra were recorded in CDCl3 (deuterated chloroform) solution phase and the UV-Vis (200-800 nm) spectrum was recorded in gas phase and ethanol solution phase. Potential energy surface (PES) scan was performed using B3LYP functional with 6-311++G (d, p) basis set. The geometrical parameters (such as bond length, bond angle, dihedral angles) and theoretical frequencies of the title compound were studied from density functional theory (DFT) using B3LYP and B3PW91 functionals with 6-311++G (d, p) basis sets. The computed frequencies were scaled and compared with the experimental values and potential energy distribution (PED) has been tabulated. A comparative study of atomic charges was made by calculating Mulliken, Natural Population Analysis (NPA) and Electrostatic Potential (ESP) simultaneously, with B3LYP/6-311++G (d, p) basis set. 1H and 13C NMR spectra were recorded and chemical shifts were compared to TMS by Gauge-Independent Atomic Orbital (GIAO) method. Electronic properties such as excitation energy, energy gap between HOMO and LUMO was calculated using time dependent DFT technique. NBO analysis, which predicts the different possibilities of electronic transition in the molecule, was computed using B3PW91 functional with 6-311++G (d, p) basis set. The thermodynamic properties such as heat capacity, entropy and enthalpy at different temperatures were computed and analyzed. Molecular docking study shows that the secondary hydroxyl group and the primary amino group in the aliphatic chain attached to the benzene ring are crucial for binding and the title compound might exhibit inhibitory activity against Bacteroides fragilis (3P24) and may act as anti-bacterial agent.

  1. Pure electrical, highly-efficient and sidelobe free coherent Raman spectroscopy using acousto-optics tunable filter (AOTF)

    Science.gov (United States)

    Meng, Zhaokai; Petrov, Georgi I.; Yakovlev, Vladislav V.

    2016-02-01

    Fast and sensitive Raman spectroscopy measurements are imperative for a large number of applications in biomedical imaging, remote sensing and material characterization. Stimulated Raman spectroscopy offers a substantial improvement in the signal-to-noise ratio but is often limited to a discrete number of wavelengths. In this report, by introducing an electronically-tunable acousto-optical filter as a wavelength selector, a novel approach to a broadband stimulated Raman spectroscopy is demonstrated. The corresponding Raman shift covers the spectral range from 600 cm-1 to 4500 cm-1, sufficient for probing most vibrational Raman transitions. We validated the use of the new instrumentation to both coherent anti-Stokes scattering (CARS) and stimulated Raman scattering (SRS) spectroscopies.

  2. Resonance Raman spectroscopic study of the interaction between Co(II)rrinoids and the ATP:corrinoid adenosyltransferase PduO from Lactobacillus reuteri.

    Science.gov (United States)

    Park, Kiyoung; Mera, Paola E; Escalante-Semerena, Jorge C; Brunold, Thomas C

    2016-09-01

    The human-type ATP:corrinoid adenosyltransferase PduO from Lactobacillus reuteri (LrPduO) catalyzes the adenosylation of Co(II)rrinoids to generate adenosylcobalamin (AdoCbl) or adenosylcobinamide (AdoCbi(+)). This process requires the formation of "supernucleophilic" Co(I)rrinoid intermediates in the enzyme active site which are properly positioned to abstract the adeonsyl moiety from co-substrate ATP. Previous magnetic circular dichroism (MCD) spectroscopic and X-ray crystallographic analyses revealed that LrPduO achieves the thermodynamically challenging reduction of Co(II)rrinoids by displacing the axial ligand with a non-coordinating phenylalanine residue to produce a four-coordinate species. However, relatively little is currently known about the interaction between the tetradentate equatorial ligand of Co(II)rrinoids (the corrin ring) and the enzyme active site. To address this issue, we have collected resonance Raman (rR) data of Co(II)rrinoids free in solution and bound to the LrPduO active site. The relevant resonance-enhanced vibrational features of the free Co(II)rrinoids are assigned on the basis of rR intensity calculations using density functional theory to establish a suitable framework for interpreting rR spectral changes that occur upon Co(II)rrinoid binding to the LrPduO/ATP complex in terms of structural perturbations of the corrin ring. To complement our rR data, we have also obtained MCD spectra of Co(II)rrinoids bound to LrPduO complexed with the ATP analogue UTP. Collectively, our results provide compelling evidence that in the LrPduO active site, the corrin ring of Co(II)rrinoids is firmly locked in place by several amino acid side chains so as to facilitate the dissociation of the axial ligand. PMID:27383231

  3. Synthesis, spectroscopic (FT-IR, FT-Raman, UV and NMR) and computational studies on 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone

    Science.gov (United States)

    Arockia doss, M.; Savithiri, S.; Rajarajan, G.; Thanikachalam, V.; Saleem, H.

    2015-09-01

    The structural and spectroscopic studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one semicarbazone (PDPOSC) were made by adopting B3LYP/HF levels theory using 6-311++G(d,p) basis set. The FT-IR and Raman spectra were recorded in solid phase, the fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. DFT method indicates that B3LYP is superior to HF method for molecular vibrational analysis. UV-vis spectrum of the compound was recorded in different solvents in the region of 200-800 nm and the electronic properties such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies were evaluated by time-dependent DFT (TD-DFT) approach. The polarizability and first order hyperpolarizability of the title molecule were calculated and interpreted. The hyperconjugative interaction energy (E(2)) and electron densities of donor (i) and acceptor (j) bonds were calculated using NBO analysis. In addition, MEP and atomic charges of carbon, nitrogen and oxygen were calculated using B3LYP/6-311++G(d,p) level theory. Moreover, thermodynamic properties of the title compound were calculated by B3LYP/HF, levels using 6-311++G(d,p) basis set. The 1H and 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  4. Resonant Raman scattering in GaAsN: Mixing, localization and band impurity formation of electronic states

    OpenAIRE

    Bachelier, Guillaume; Mlayah, A.; Cazayous, M.; Groenen, J.; Zwick, Antoine; Carrère, Hélène; Bedel, Eléna; Arnoult, Alexandre; Rocher, A.; Ponchet, A.

    2003-01-01

    Raman measurements on a thick GaAsN layer and on GaAsN/GaAs quantum well structures are reported. The scattering was excited close to resonance with the N-induced E+ transition, and detected in both Stokes and anti-Stokes regions including the low-frequency range around the Rayleigh line. A broad continuous scattering due to acoustic phonons is observed on the thick GaAsN layer. Calculations of the Raman efficiency showed that localization and mixing of the resonant electronic states well acc...

  5. Tip-enhanced THz Raman spectroscopy for local temperature determination at the nanoscale.

    Science.gov (United States)

    Balois, Maria Vanessa; Hayazawa, Norihiko; Catalan, Francesca Celine; Kawata, Satoshi; Yano, Taka-Aki; Hayashi, Tomohiro

    2015-11-01

    Local temperature of a nanoscale volume is precisely determined by tip-enhanced terahertz Raman spectroscopy in the low temperature range of several tens of degrees. Heat generated by the tip-enhanced electric field is directly transferred to single-walled carbon nanotubes by heat conduction and radiation at the nanoscale. This heating modulates the intensity ratio of anti-Stokes/Stokes Raman scattering of the radial breathing mode of the carbon nanotube based on the Boltzmann distribution at elevated temperatures. Owing to the low-energy feature of the radial breathing mode, the local temperature of the probing volume has been successfully extracted with high sensitivity. The dependence of the temperature rise underneath the tip apex on the incident power coincides with the analytical results calculated by finite element method based on the tip enhancement effect and the consequent steady-state temperature via Joule heat generation. The results show that the local temperature at the nanoscale can be controlled in the low temperature range simply by the incident laser power while exhibiting a sufficiently high tip enhancement effect as an analytical tool for thermally sensitive materials (e.g., proteins, DNA). Graphical Abstract Tip-enhanced THz Raman spectroscopy detects the low frequency Raman mode both in Stokes and anti-Stokes shifts, which precisely reflects the local temperature of the sample volume. PMID:26164304

  6. In Situ Raman Spectroscopic Study of Gypsum (CaSO4·2H2O) and Epsomite (MgSO4·7H2O) Dehydration Utilizing an Ultrasonic Levitator.

    Science.gov (United States)

    Brotton, Stephen J; Kaiser, Ralf I

    2013-02-21

    We present an original apparatus combining an acoustic levitator and a pressure-compatible process chamber. To characterize in situ the chemical and physical modifications of a levitated, single particle while heated to well-defined temperatures using a carbon dioxide laser, the chamber is interfaced to a Raman spectroscopic probe. As a proof-of-concept study, by gradually increasing the heating temperature, we observed the variations in the Raman spectra as 150 μg of crystals of gypsum and epsomite were dehydrated in anhydrous nitrogen gas. We display spectra showing the decreasing intensities of the ν1 symmetric and ν3 asymmetric stretching modes of water with time and the simultaneous shift of the ν1(SO4(2-)) symmetric stretch mode to higher wavenumbers. Our results demonstrate that the new apparatus is well suited to study the dehydration of levitated species such as minerals and offers potential advantages compared with previous experiments on bulk samples. PMID:26281883

  7. Multimode Raman light-atom interface in warm atomic ensemble as multiple three-mode quantum operations

    CERN Document Server

    Parniak, Michał; Wasilewski, Wojciech

    2015-01-01

    We analyze the properties of a Raman quantum light-atom interface in long atomic ensemble and its applications as a quantum memory or two-mode squeezed state generator. We include both Stokes and anti-Stokes scattering and the effects of Doppler broadening in buffer gas assuming frequent velocity-averaging collisions. We find the Green functions describing multimode transformation from input to output fields of photons and atomic excitations. Proper mode basis is found via singular value decomposition. It reveals that triples of modes are coupled by a transformation equivalent to a combination of two beamsplitters and a two-mode squeezing operation. We analyze the possible transformations on an example of warm rubidium-87 vapor. We find that the fidelity of the mapping of a single excitation between the memory and light is strictly limited by the fractional contribution of the Stokes scattering in predominantly anti-Stokes process. The model we present bridges the gap between the Stokes only and anti-Stokes o...

  8. Stimulated Stokes and Antistokes Raman Scattering in Microspherical Whispering Gallery Mode Resonators.

    Science.gov (United States)

    Farnesi, Daniele; Berneschi, Simone; Cosi, Franco; Righini, Giancarlo C; Soria, Silvia; Nunzi Conti, Gualtiero

    2016-01-01

    Dielectric microspheres can confine light and sound for a length of time through high quality factor whispering gallery modes (WGM). Glass microspheres can be thought as a store of energy with a huge variety of applications: compact laser sources, highly sensitive biochemical sensors and nonlinear phenomena. A protocol for the fabrication of both the microspheres and coupling system is given. The couplers described here are tapered fibers. Efficient generation of nonlinear phenomena related to third order optical non-linear susceptibility Χ((3)) interactions in triply resonant silica microspheres is presented in this paper. The interactions here reported are: Stimulated Raman Scattering (SRS), and four wave mixing processes comprising Stimulated Anti-stokes Raman Scattering (SARS). A proof of the cavity-enhanced phenomenon is given by the lack of correlation among the pump, signal and idler: a resonant mode has to exist in order to obtain the pair of signal and idler. In the case of hyperparametric oscillations (four wave mixing and stimulated anti-stokes Raman scattering), the modes must fulfill the energy and momentum conservation and, last but not least, have a good spatial overlap. PMID:27078752

  9. A Raman and infrared spectroscopic study of the sulphate mineral aluminite Al2(SO4)(OH)4·7H2O

    Science.gov (United States)

    Frost, Ray L.; López, Andrés; Scholz, Ricardo; Wang, Lina

    2015-09-01

    The mineral aluminite has been studied using a number of techniques, including scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDX) and Raman and infrared spectroscopy. Raman spectroscopy identifies multiple sulphate symmetric stretching modes in line with the three sulphate crystallographically different sites. Raman spectroscopy also identifies a low intensity band at 1069 cm-1 which may be attributed to a carbonate symmetric stretching mode, indicating the presence of thaumasite. The observation of multiple bands in this ν4 spectral region offers evidence for the reduction in symmetry of the sulphate anion from Td to C2v or even lower symmetry. The Raman band at 3588 cm-1 is assigned to the OH unit stretching vibration and the broad feature at around 3439 cm-1 to water stretching bands. Water stretching vibrations are observed at 3157, 3294, 3378 and 3439 cm-1. Vibrational spectroscopy enables an assessment of the molecular structure of aluminite to be made.

  10. Raman and infrared spectroscopic studies of the structure of water (H2O, HOD, D2O) in stoichiometric crystalline hydrates and in electrolyte solutions

    International Nuclear Information System (INIS)

    The chapter of reviews presents in particular the Badger-Bauer-rule, distance and angle dependence of O-H...Y hydrogen bond and the structure of aqueous electrolyte solutions. A chapter of vibrational spectroscopic investigations of crystalline hydrates - metal perchlorate hydrates follows. Two further chapters just so investigate metal halide hydrates and some sulfate hydrates and related systems. The following chapter describes near infrared spectroscopic investigations of HOD(D2O) and its electrolyte solutions. The concluding chapter contains thermodynamic consequences and some properties of electrolyte solutions from vibrational spectroscopic investigations. (SPI)

  11. Phase-shift effect of amplitude spread function on spectrum and image formation in coherent Raman scattering microspectroscopy.

    Science.gov (United States)

    Fukutake, Naoki

    2016-03-01

    Coherent Raman scattering microspectroscopy, which includes coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS) microspectroscopy, permits label-free hyperspectral imaging. We report the theoretical study of the phase-shift effect of the impulse response function on the spectral and image-forming properties of coherent Raman scattering microspectroscopy. We show that the spectrum and image are influenced by not only the NA of objective for excitation (NA(ex)) but also that for signal collection (NA(col)), in association with the phase-shift effect. We discuss that, under the condition NA(ex)≠NA(col), both the spectrum and the image become deformed by the phase-shift effect, which can be applied to the direct measurement of the imaginary part of the nonlinear susceptibility in CARS spectroscopy. We point out that, even in SRS microscopy, the nonresonant background can contribute to the image formation and cause the artifact in the image.

  12. Non-invasive in vivo determination of the carotenoids beta-carotene and lycopene concentrations in the human skin using the Raman spectroscopic method

    International Nuclear Information System (INIS)

    Resonance Raman spectroscopy was used as a fast and non-invasive optical method of measuring the absolute concentrations of beta-carotene and lycopene in living human skin. Beta-carotene and lycopene have different absorption values at 488 and 514.5 nm and, consequently, the Raman lines for beta-carotene and lycopene have different scattering efficiencies at 488 and 514.5 nm excitations. These differences were used for the determination of the concentrations of beta-carotene and lycopene. Using multiline Ar+ laser excitation, clearly distinguishable carotenoid Raman spectra can be obtained which are superimposed on a large fluorescence background. The Raman signals are characterized by two prominent Stokes lines at 1160 and 1525 cm-1, which have nearly identical relative intensities. Both substances were detected simultaneously. The Raman spectra are obtained rapidly, i.e. within about 10 s, and the required laser light exposure level is well within safety standards. The disturbance of the measurements by non-homogeneous skin pigmentation was avoided by using a relatively large measuring area of 35 mm2. It was shown that beta-carotene and lycopene distribution in human skin strongly depends upon the skin region studied and drastically changed inter-individually. Skin beta-carotene and lycopene concentrations are lower in smokers than in non-smokers and higher in the vegetarian group

  13. Non-invasive in vivo determination of the carotenoids beta-carotene and lycopene concentrations in the human skin using the Raman spectroscopic method

    Energy Technology Data Exchange (ETDEWEB)

    Darvin, M E [Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charite University Hospital, Berlin (Germany); Gersonde, I [Institute of Medical Physics and Laser Medicine, Charite University Hospital, Berlin (Germany); Meinke, M [Institute of Medical Physics and Laser Medicine, Charite University Hospital, Berlin (Germany); Sterry, W [Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charite University Hospital, Berlin (Germany); Lademann, J [Center of Experimental and Applied Cutaneous Physiology (CCP), Department of Dermatology, Charite University Hospital, Berlin (Germany)

    2005-08-07

    Resonance Raman spectroscopy was used as a fast and non-invasive optical method of measuring the absolute concentrations of beta-carotene and lycopene in living human skin. Beta-carotene and lycopene have different absorption values at 488 and 514.5 nm and, consequently, the Raman lines for beta-carotene and lycopene have different scattering efficiencies at 488 and 514.5 nm excitations. These differences were used for the determination of the concentrations of beta-carotene and lycopene. Using multiline Ar{sup +} laser excitation, clearly distinguishable carotenoid Raman spectra can be obtained which are superimposed on a large fluorescence background. The Raman signals are characterized by two prominent Stokes lines at 1160 and 1525 cm{sup -1}, which have nearly identical relative intensities. Both substances were detected simultaneously. The Raman spectra are obtained rapidly, i.e. within about 10 s, and the required laser light exposure level is well within safety standards. The disturbance of the measurements by non-homogeneous skin pigmentation was avoided by using a relatively large measuring area of 35 mm{sup 2}. It was shown that beta-carotene and lycopene distribution in human skin strongly depends upon the skin region studied and drastically changed inter-individually. Skin beta-carotene and lycopene concentrations are lower in smokers than in non-smokers and higher in the vegetarian group.

  14. A UV resonance Raman (UVRR) spectroscopic study on the extractable compounds of Scots pine ( Pinus sylvestris) wood . Part I: Lipophilic compounds

    Science.gov (United States)

    Nuopponen, M.; Willför, S.; Jääskeläinen, A.-S.; Sundberg, A.; Vuorinen, T.

    2004-11-01

    The wood resin in Scots pine ( Pinus sylvestris) stemwood and branch wood were studied using UV resonance Raman (UVRR) spectroscopy. UVRR spectra of the sapwood and heartwood hexane extracts, solid wood samples and model compounds (six resin acids, three fatty acids, a fatty acid ester, sitosterol and sitosterol acetate) were collected using excitation wavelengths of 229, 244 and 257 nm. In addition, visible Raman spectra of the fatty and resin acids were recorded. Resin compositions of heartwood and sapwood hexane extracts were determined using gas chromatography. Raman signals of both conjugated and isolated double bonds of all the model compounds were resonance enhanced by UV excitation. The oleophilic structures showed strong bands in the region of 1660-1630 cm -1. Distinct structures were enhanced depending on the excitation wavelength. The UVRR spectra of the hexane extracts showed characteristic bands for resin and fatty acids. It was possible to identify certain resin acids from the spectra. UV Raman spectra collected from the solid wood samples containing wood resin showed a band at ˜1650 cm -1 due to unsaturated resin components. The Raman signals from extractives in the resin rich branch wood sample gave even more strongly enhanced signals than the aromatic lignin.

  15. Spectroscopic properties of KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals studied by Brillouin and Raman scattering methods

    Science.gov (United States)

    Kasprowicz, D.; Runka, T.; Szybowicz, M.; Drozdowski, M.; Majchrowski, A.; Michalski, E.; Żmija, J.

    2006-07-01

    KGd(WO 4) 2 single crystals, pure and doped with holmium ions Ho 3+ at 0.5 and 1% concentrations were investigated by Brillouin and Raman scattering methods. Polarized Raman spectra of KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals have been measured at room temperature. The assignment of the Raman-active A g and B g modes have been performed. Brillouin spectra were collected for the acoustic phonons propagating in [100], [001], [101], [-101], [110], [-110], [011] and [0-11] directions in KGd(WO 4) 2 and KGd(WO 4) 2:Ho 3+ single crystals at room temperature. Obtained results have been discussed in terms of the influence of the doping concentration on the lattice dynamics and crystal structure.

  16. In situ cryogenic Raman spectroscopic studies on the synthetic fluid inclusions in the systems H2O and NaCl-H2O

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Salt-hydrates have diagnostic cryogenic Raman spectra, which can reflect the composition of the parent solutions. As analogue to the natural fluid inclusions, the synthetic inclusions can be used to validate numerous assumptions related to fluid inclusion research. They can also be used to test the feasibility of application of laser Raman spectroscopy to individual fluid inclusion analysis. Using the technique proposed by Sterner and Bodnar(1984), synthetic inclusions of the systems H2O and NaCl-H2O (with NaCl as 5.12 wt%, 9.06 wt%, 16.6 wt% and 25 wt%) were formed under the pressures from 50Mpa to 100Mpa and at the temperatures from 500℃ to 600℃. In situ cryogenic Raman spectra were collected at about -180℃ by combined use of freezing- heating stage and Laser Raman Microscopy. It is shown that hydrohalite (NaCl·2H2O), the salt-hydrate of NaCl in the fluid inclusions has the specific Raman spectrum and can be used as the standard to verify the existence of NaCl in the aqueous inclusions. The crystalline ice other than amorphous ice (glasses) formed from the aqueous phase whthin the synthetic inclusions during the initial freezing, but hydrohalite did not form. Subsequent warming of these inclusions induced a phase change, typically between approximately -40 and -22℃, that represents the hydrohalite crystallization event but not a eutectic melting event. So, for fluid inclusions in the system NaCl-H2O, interpretation of phase behavior below the eutectic temperature (-20.8℃) should be made with caution. The ratios of the relative intensity and the area of Raman spectra between 3423 cm-1 peak of hydrohalite and 3098 cm-1 peak of ice show positive correlations to the salinities in aqueous inclusions, which can be used to determine the salinity of NaCl- H2O system inclusions.

  17. Structural and spectroscopic study of a pectin isolated from citrus peel by using FTIR and FT-Raman spectra and DFT calculations

    Science.gov (United States)

    Bichara, Laura C.; Alvarez, Patricia E.; Fiori Bimbi, María V.; Vaca, Hugo; Gervasi, Claudio; Brandán, Silvia Antonia

    2016-05-01

    In this work, pectin isolated from citrus peel with a degree of esterification of 76% was characterized by Fourier Transform Infrared (FTIR) and Fourier Transform Raman (FT-Raman) spectroscopies. Structural studies were carried out taking into account their partial degree of esterification and considering the polygalacturonic acid chain as formed by two different subunits, one with both COOH and COOsbnd CH3 groups (Ac) and the other one as constituted by two subunits with two COOsbnd CH3 groups (Es). Their structural properties, harmonic frequencies, force fields and force constants in gas and aqueous solution phases were calculated by using the hybrid B3LYP/6-31G∗ method. Then, their complete vibrational analyses were performed by using the IR and Raman spectra accomplished with the scaled quantum mechanical (SQM) methodology. Reactivities and behaviors in both media were predicted for Ac and Es by using natural bond orbital (NBO), atoms in molecules (AIM), and frontier orbitals calculations. We report for first time the complete assignments of those two different units of polygalacturonic acid chain which are the 132 normal vibration modes of Ac and the 141 normal vibration modes of Es, combining the normal internal coordinates with the SQM methodology. In addition, three subunits were also studied. Reasonable correlations between the experimental and theoretical spectra were obtained. Thus, this work would allow the quick identification of pectin by using infrared and Raman spectroscopies and also provides new insight into the interactions that exist between subunits of a large pectin chain.

  18. Molecular structure, spectroscopic studies (FTIR, FT-Raman and NMR) and HOMO-LUMO analysis of 6-chloro-o-cresol and 4-chloro-3-methyl phenol by density functional theoretical study.

    Science.gov (United States)

    Krishnakumar, V; Kumar, M; Prabavathi, N; Mathammal, R

    2012-11-01

    In this work, the experimental and theoretical vibrational spectra of 6-chloro-o-cresol (COC) and 4-chloro-3-methylphenol (CMP) have been studied. FTIR and FT-Raman spectra of the title compounds in the solid phase are recorded in the region 4000-400 cm(-1) and 4000-50 cm(-1), respectively. The structural and spectroscopic data of the molecules in the ground state are calculated by using density functional methods (B3LYP) with 6-31G basis set combinations. The calculated vibrational frequencies are scaled by normal coordinate analysis based on a scaled quantum mechanical force field. The obtained values are compared with experimental FTIR and FT-Raman spectra. The observed and calculated frequencies are found to be in good agreement. The complete vibrational assignments are performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The results of (13)C and (1)H NMR chemical shift are compared with the experimental values. PMID:22750683

  19. Influence of curvature strain and Van der Waals force on the inter-layer vibration mode of WS2 nanotubes: A confocal micro-Raman spectroscopic study

    Science.gov (United States)

    Wang, Xiao Hu; Zheng, Chang Cheng; Ning, Ji Qiang

    2016-09-01

    Transition-metal dichalcogenides (TMDs) nanostructures including nanotubes and monolayers have attracted great interests in materials science, chemistry to condensed matter physics. We present an interesting study of the vibration modes in multi-walled tungsten sulfide (WS2) nanotubes prepared via sulfurizing tungsten oxide (WO3) nanowires which are investigated by confocal micro-Raman spectroscopy. The inter-layer vibration mode of WS2 nanotubes, A1g, is found to be sensitive to the diameter and curvature strain, while the in-plane vibration mode, E12g, is not. A1g mode frequency shows a redshift by 2.5 cm-1 for the multi-layered nanotubes with small outer-diameters, which is an outcome of the competition between the Van der Waals force stiffening and the curvature strain softening. We also show that the Raman peak intensity ratio is significantly different between the 1-2 wall layered nanotubes and monolayer flat sheets.

  20. Infrared, Raman, and visible spectroscopic studies of Zn and Cd matrix reactions with ozone. Spectra of metal ozonides and oxides in solid argon and nitrogen

    Science.gov (United States)

    Prochaska, Eleanor S.; Andrews, Lester

    1980-06-01

    Reactions of zinc and cadmium atoms with ozone during condensation with excess nitrogen or argon produced B+O3- ion-pairs having infrared, Raman, and optical spectra similar to the analogous alkali and alkaline earth metal species. Additional infrared and Raman evidence was found for a different B+O3- ion-pair geometry. Mercury arc photolysis reduced ozonide absorptions and produced new 810 cm-1 zinc isotopic triplets which showed the appropriate 18O shifts for ZnO, and a new 719 cm-1 band which showed the proper 18O displacement for CdO. This nitrogen matrix work provides good measures of the yet-to-be-observed gas-phase fundamentals of these high temperature oxides.

  1. Primidone - An antiepileptic drug - characterisation by quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR and UV-Visible) investigations

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Subramanian, S.; Mohan, S.

    2013-05-01

    The solid phase FTIR and FT-Raman spectra of primidone were recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The vibrational spectra were analysed and the observed fundamentals were assigned and analysed. The experimental wavenumbers were compared with the theoretical scaled vibrational wavenumbers determined by DFT methods. The Raman intensities were also determined with B3LYP/6-31G(d,p) method. The total electron density and molecular electrostatic potential surface of the molecule were constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The HOMO and LUMO energies were measured. Natural bond orbital analysis of primidone has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR spectra were recorded and the chemical shifts of the molecule were calculated.

  2. Random Raman lasing

    CERN Document Server

    Hokr, Brett H; Mason, John D; Beier, Hope T; Rockwll, Benjamin A; Thomas, Robert J; Noojin, Gary D; Petrov, Georgi I; Golovan, Leonid A; Yakovlev, Vladislav V

    2013-01-01

    Propagation of light in a highly scattering medium is among the most fascinating optical effect that everyone experiences on an everyday basis and possesses a number of fundamental problems which have yet to be solved. Conventional wisdom suggests that non-linear effects do not play a significant role because the diffusive nature of scattering acts to spread the intensity, dramatically weakening these effects. We demonstrate the first experimental evidence of lasing on a Raman transition in a bulk three-dimensional random media. From a practical standpoint, Raman transitions allow for spectroscopic analysis of the chemical makeup of the sample. A random Raman laser could serve as a bright Raman source allowing for remote, chemically specific, identification of powders and aerosols. Fundamentally, the first demonstration of this new light source opens up an entire new field of study into non-linear light propagation in turbid media, with the most notable application related to non-invasive biomedical imaging.

  3. Monomeric and dimeric structures analysis and spectroscopic characterization of 3,5-difluorophenylboronic acid with experimental (FT-IR, FT-Raman, 1H and 13C NMR, UV) techniques and quantum chemical calculations

    Science.gov (United States)

    Karabacak, Mehmet; Kose, Etem; Atac, Ahmet; Asiri, Abdullah M.; Kurt, Mustafa

    2014-01-01

    The spectroscopic properties of 3,5-difluorophenylboronic acid (3,5-DFPBA, C6H3F2B(OH)2) were investigated by FT-IR, FT-Raman UV-Vis, 1H and 13C NMR spectroscopic techniques. FT-IR (4000-400 cm-1) and FT-Raman spectra (3500-10 cm-1) in the solid phase and 1H and 13C NMR spectra in DMSO solution were recorded. The UV spectra that dissolved in ethanol and water were recorded in the range of 200-400 nm for each solution. The structural and spectroscopic data of the molecule have been obtained for possible three conformers from DFT (B3LYP) with 6-311++G(d,p) basis set calculations. The geometry of the molecule was fully optimized, vibrational spectra were calculated and fundamental vibrations were assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. Hydrogen-bonded dimer of title molecule, optimized by counterpoise correction, was also studied B3LYP at the 6-311++G(d,p) level and the effects of molecular association through O-H⋯O hydrogen bonding have been discussed. 1H and 13C NMR chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The electronic properties, such as excitation energies, oscillator strength, wavelengths, HOMO and LUMO energies, were performed by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. Total and partial density of state (TDOS and PDOS) and also overlap population density of state (OPDOS) diagrams analysis were presented. The effects due to the substitutions of boric acid group and halogen were investigated. The results of the calculations were applied to simulate spectra of the title compound, which show excellent agreement with observed spectra. Besides, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), nonlinear optical properties (NLO) and thermodynamic features were performed.

  4. Raman spectroscopic determination of the length, strength, compressibility, Debye temperature, elasticity, and force constant of the C-C bond in graphene.

    Science.gov (United States)

    Yang, X X; Li, J W; Zhou, Z F; Wang, Y; Yang, L W; Zheng, W T; Sun, Chang Q

    2012-01-21

    From the perspective of bond relaxation and bond vibration, we have formulated the Raman phonon relaxation of graphene, under the stimuli of the number-of-layers, the uni-axial strain, the pressure, and the temperature, in terms of the response of the length and strength of the representative bond of the entire specimen to the applied stimuli. Theoretical unification of the measurements clarifies that: (i) the opposite trends of the Raman shifts, which are due to the number-of-layers reduction, of the G-peak shift and arises from the vibration of a pair of atoms, while the D- and the 2D-peak shifts involve the z-neighbor of a specific atom; (ii) the tensile strain-induced phonon softening and phonon-band splitting arise from the asymmetric response of the C(3v) bond geometry to the C(2v) uni-axial bond elongation; (iii) the thermal softening of the phonons originates from bond expansion and weakening; and (iv) the pressure stiffening of the phonons results from bond compression and work hardening. Reproduction of the measurements has led to quantitative information about the referential frequencies from which the Raman frequencies shift as well as the length, energy, force constant, Debye temperature, compressibility and elastic modulus of the C-C bond in graphene, which is of instrumental importance in the understanding of the unusual behavior of graphene.

  5. Implementation of Rotational Raman Channel in Multiwavelength Aerosol Lidar to Improve Measurements of Particle Extinction and Backscattering at 532 NM

    Directory of Open Access Journals (Sweden)

    Veselovskii Igor

    2016-01-01

    Full Text Available We describe a practical implementation of rotational Raman (RR measurements in an existing Mie-Raman lidar to obtain measurements of aerosol extinction and backscattering at 532 nm. A 2.3 nm width interference filter was used to select a spectral range characterized by low temperature sensitivity within the anti-Stokes branch of the RR spectrum. Simulations demonstrate that the temperature dependence of the scattering cross section does not exceed 1.0% in the 230-300K range making accurate correction for this dependence quite easy. With this upgrade, the NASA/GSFC multiwavelength Raman lidar has demonstrated useful α532 measurements and was used for regular observations. Examples of lidar measurements and inversion of optical data to the particle microphysics will be given in presentation.

  6. High precision stress measurements in semiconductor structures by Raman microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uhlig, Benjamin

    2009-07-01

    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.)

  7. Raman micro-spectroscopic investigation of the interaction of cultured HCT116 colon cancer cells with alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase

    Science.gov (United States)

    Akyuz, S.; Ozel, A. E.; Balci, K.; Akyuz, T.; Coker, A.; Arisan, E. D.; Palavan-Unsal, N.; Ozalpan, A.

    2011-05-01

    The interaction of cultured colon cancer cells with alpha-difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, has been investigated, using Raman micro-spectroscopy, in order to investigate DFMO induced effects. Raman spectra of the cultured HCT116 colon cancer cells treated with DFMO at different concentrations (0, 1, 2.5, 5, and 7.5 mM) were recorded in the range 550-2300 cm -1. It has been shown that second derivative profile of the raw Raman spectrum of the colon cancer cells (i.e., the original experimental spectrum without any computational corrections) discriminates the weak but sharp bands from the strong, broad fluorescence background, and gives information about the position of the peaks and their band widths. The relative integrated intensities of the 781 cm -1 and 788 cm -1 DNA/RNA marker bands to that of 1451 cm -1 band are found to decrease by addition of DFMO. Up to 65% reduction in the magnitude of the 1003 cm -1 band, the characteristic phenylalanine ring breathing mode, in comparison to that of 1451 band, is observed. The results indicate DFMO induced apoptosis. On the other hand the intensity ratio of the tyrosine Fermi doubled around 830 cm -1 and 850 cm -1, which is a marker of hydrogen-bonding state of phenolic OH, is changed. The addition of DFMO may alter the tyrosine environment in cells, and parts of tyrosine residues are exposed. We also observed some modifications in amide I band, pointing out the alterations of the secondary structure of cell proteins by the presence of DFMO.

  8. Freezing nucleation of levitated single sulfuric acid/H 2O micro-droplets. A combined Raman- and Mie spectroscopic study

    Science.gov (United States)

    Mund, C.; Zellner, R.

    2003-12-01

    The phase behaviour of single sulfuric acid/H 2O micro-droplets upon supercooling has been studied using optical levitation of such droplets in combination with Raman- and Mie spectroscopy for chemical and size analysis. It is found that the freezing nucleation behaviour depends on the sulfuric acid concentration of the droplets and hence the region of the phase diagram which is reached upon cooling. Whereas for diluted droplets (c H2SO4SAT) or sulfuric acid monohydrate (SAM). The upper limits of the nucleation rate in this regime were determined to be J≤5×10 5 cm -3 s -1.

  9. Enhanced Raman spectroscopic study of the coordination chemistry of malononitrile on copper surfaces - Removal of nu(C=N) degeneracy through pi-coordination

    Science.gov (United States)

    Loo, B. H.; Lee, Y. G.; Frazier, D. O.

    1985-01-01

    Surface-enhanced Raman spectroscopy has been used to study the molecular interactions of malononitrile with copper electrode surfaces. The doubly degenerate CN stretching frequency at 2263/cm is removed when malononitrile adsorbs on copper. Two nu(CN) bands are observed at 2096 and 2204/cm at -0.6 V(SCE). The result shows that only one CN group is pi-coordinated with Cu, which contributes to the observed large shift (-167/cm) in nu(CN). The other CN group is not coordinated to the metal surface.

  10. Generation and delayed retrieval of spatially multimode Raman scattering in warm rubidium vapors

    CERN Document Server

    Chrapkiewicz, Radoslaw

    2014-01-01

    We apply collective Raman scattering to create, store and retrieve spatially multimode light in warm rubidium-87 vapors. The light is created in a spontaneous Stokes scattering process. This is accompanied by the creation of counterpart collective excitations in the atomic ensemble -- the spin waves. After a certain storage time we coherently convert the spin waves into the light in deterministic anti-Stokes scattering. The whole process can be regarded as a delayed four-wave mixing which produces pairs of correlated, delayed random images. Storage of higher order spatial modes up to microseconds is possible owing to usage of a buffer gas. We study the performance of the Raman scattering, storage and retrieval of collective excitations focusing on spatial effects and the influence of decoherence caused by diffusion of rubidium atoms in different buffer gases. We quantify the number of modes created and retrieved by analyzing statistical correlations of intensity fluctuations between portions of the light scat...

  11. Raman Scattering of Water and Photoluminescence of Pollutants Arising from Solid-Water Interaction

    CERN Document Server

    Vallée, P; Ghomi, M; Jouanne, M; Vall\\'{e}e, Philippe; Lafait, Jacques; Ghomi, Mahmoud; Jouanne, Michel

    2003-01-01

    Systematic Raman experiments performed on water and water-ethanol samples, stored in different containers (fused silica, polypropylene, soda-lime glass type III) for several hours, have shown that the luminescence contribution to the Raman signal fluctuations is directly related to the container composition. Intensity fluctuations as large as 98%, have been observed in the spectral regions corresponding to the both water intramolecular and intermolecular vibrations, despite the fact that the wavenumbers of the modes remained unchanged. We undoubtedly attribute these fluctuations to a luminescence phenomenon on the basis of : i) the absence of such effect in the anti-Stokes domain, ii) its dependence on the excitation laser wavelength, iii) other relevant photoluminescence experiments. This luminescence is attributed to pollutants at ultra-low concentration coming from the different containers.

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

    Energy Technology Data Exchange (ETDEWEB)

    Alfano, Robert R. (Bronx, NY); Wang, Wubao (Flushing, NY)

    2003-05-06

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

  13. A micro-Raman spectroscopic investigation of leukemic U-937 cells treated with Crotalaria agatiflora Schweinf and the isolated compound madurensine

    Science.gov (United States)

    le Roux, Karlien; Prinsloo, Linda C.; Hussein, Ahmed A.; Lall, Namrita

    In South Africa traditional medicine plays an important role in primary health care and therefore it is very important that the medicinal use of plants is scientifically tested for toxicity and effectiveness. It was established that the ethanolic extract of the leaves of Crotalaria agatiflora, as well as the isolated compound madurensine, is moderately toxic against leukemic U-937 cells. Light microscopic investigations indicated that symptoms of cell death are induced during treatments, but flow cytometry analysis of treated cells, using annexin-V and propidium iodide, showed that apoptosis and necrosis are insignificantly induced. The Raman results suggested that protein extraction and DNA melting occur in the cells during treatment with the ethanolic extracts (IC50 value 73.9 μg/mL), drastically changing the molecular content of the cells. In contrast, treatment with madurensine (IC50 value 136.5 μg/mL), an isolated pyrrolizidine alkaloid from the ethanolic extract of the leaves, did not have the same effect. The results are also compared to that of cells treated with actinomycin D, a compound known to induce apoptosis. The investigation showed that micro-Raman spectroscopy has great promise to be used for initial screening of samples to determine the effects of different treatments on cancerous cell lines together with conventional methods. The results highlight the fact that for many natural products used for medicinal purposes, the therapeutic effect of the crude plant extract tends to be significantly more effective than the particular action of its individual constituents.

  14. Raman spectroscopic measurements of CO2 density: Experimental calibration with high-pressure optical cell (HPOC) and fused silica capillary capsule (FSCC) with application to fluid inclusion observations

    Science.gov (United States)

    Wang, X.; Chou, I.-Ming; Hu, W.; Burruss, R.C.; Sun, Q.; Song, Y.

    2011-01-01

    Raman spectroscopy is a powerful method for the determination of CO2 densities in fluid inclusions, especially for those with small size and/or low fluid density. The relationship between CO2 Fermi diad split (??, cm-1) and CO2 density (??, g/cm3) has been documented by several previous studies. However, significant discrepancies exist among these studies mainly because of inconsistent calibration procedures and lack of measurements for CO2 fluids having densities between 0.21 and 0.75g/cm3, where liquid and vapor phases coexist near room temperature.In this study, a high-pressure optical cell and fused silica capillary capsules were used to prepare pure CO2 samples with densities between 0.0472 and 1.0060g/cm3. The measured CO2 Fermi diad splits were calibrated with two well established Raman bands of benzonitrile at 1192.6 and 1598.9cm-1. The relationship between the CO2 Fermi diad split and density can be represented by: ??=47513.64243-1374.824414????+13.25586152????2-0.04258891551????3 (r2=0.99835, ??=0.0253g/cm3), and this relationship was tested by synthetic fluid inclusions and natural CO2-rich fluid inclusions. The effects of temperature and the presence of H2O and CH4 on this relationship were also examined. ?? 2011 Elsevier Ltd.

  15. A grid matrix-based Raman spectroscopic method to characterize different cell milieu in biopsied axillary sentinel lymph nodes of breast cancer patients.

    Science.gov (United States)

    Som, Dipasree; Tak, Megha; Setia, Mohit; Patil, Asawari; Sengupta, Amit; Chilakapati, C Murali Krishna; Srivastava, Anurag; Parmar, Vani; Nair, Nita; Sarin, Rajiv; Badwe, R

    2016-01-01

    Raman spectroscopy which is based upon inelastic scattering of photons has a potential to emerge as a noninvasive bedside in vivo or ex vivo molecular diagnostic tool. There is a need to improve the sensitivity and predictability of Raman spectroscopy. We developed a grid matrix-based tissue mapping protocol to acquire cellular-specific spectra that also involved digital microscopy for localizing malignant and lymphocytic cells in sentinel lymph node biopsy sample. Biosignals acquired from specific cellular milieu were subjected to an advanced supervised analytical method, i.e., cross-correlation and peak-to-peak ratio in addition to PCA and PC-LDA. We observed decreased spectral intensity as well as shift in the spectral peaks of amides and lipid bands in the completely metastatic (cancer cells) lymph nodes with high cellular density. Spectral library of normal lymphocytes and metastatic cancer cells created using the cellular specific mapping technique can be utilized to create an automated smart diagnostic tool for bench side screening of sampled lymph nodes. Spectral library of normal lymphocytes and metastatic cancer cells created using the cellular specific mapping technique can be utilized to develop an automated smart diagnostic tool for bench side screening of sampled lymph nodes supported by ongoing global research in developing better technology and signal and big data processing algorithms.

  16. A grid matrix-based Raman spectroscopic method to characterize different cell milieu in biopsied axillary sentinel lymph nodes of breast cancer patients.

    Science.gov (United States)

    Som, Dipasree; Tak, Megha; Setia, Mohit; Patil, Asawari; Sengupta, Amit; Chilakapati, C Murali Krishna; Srivastava, Anurag; Parmar, Vani; Nair, Nita; Sarin, Rajiv; Badwe, R

    2016-01-01

    Raman spectroscopy which is based upon inelastic scattering of photons has a potential to emerge as a noninvasive bedside in vivo or ex vivo molecular diagnostic tool. There is a need to improve the sensitivity and predictability of Raman spectroscopy. We developed a grid matrix-based tissue mapping protocol to acquire cellular-specific spectra that also involved digital microscopy for localizing malignant and lymphocytic cells in sentinel lymph node biopsy sample. Biosignals acquired from specific cellular milieu were subjected to an advanced supervised analytical method, i.e., cross-correlation and peak-to-peak ratio in addition to PCA and PC-LDA. We observed decreased spectral intensity as well as shift in the spectral peaks of amides and lipid bands in the completely metastatic (cancer cells) lymph nodes with high cellular density. Spectral library of normal lymphocytes and metastatic cancer cells created using the cellular specific mapping technique can be utilized to create an automated smart diagnostic tool for bench side screening of sampled lymph nodes. Spectral library of normal lymphocytes and metastatic cancer cells created using the cellular specific mapping technique can be utilized to develop an automated smart diagnostic tool for bench side screening of sampled lymph nodes supported by ongoing global research in developing better technology and signal and big data processing algorithms. PMID:26552923

  17. Raman spectroscopic detection of rapid, reversible, early-stage inflammatory cytokine-induced apoptosis of adult hippocampal progenitors/stem cells

    CERN Document Server

    Ladiwala, Uma; Thakur, Bhushan; Santhosh, Chidangil; Mathur, Deepak

    2014-01-01

    The role of neuro-inflammation in diverse, acute and chronic brain pathologies is being increasingly recognized. Neuro-inflammation is accompanied by increased levels of both pro- and anti-inflammatory cytokines; these have deleterious as well as protective/reparative effects. Inflammation has varying effects on neurogenesis and is a subject of intense contemporary interest. We show that TNF-alpha and IFN-gamma, used concomitantly, cause apoptosis of adult rat hippocampal progenitor/stem cells in vitro as detected by the TUNEL and MTT assays on time scales of several hours. We have coupled Raman spectroscopy to an optical trap to probe early changes of apoptosis in single, live neural stem cells that have been treated with pro-inflammatory cytokines, TNF-alpha and IFN-gamma. Changes caused by inflammation-induced denaturation of DNA are observed in the Raman spectra that correspond to very early stages of apoptosis, occurring on very fast time scales: as short as 10 minutes. Addition of the anti-inflammatory ...

  18. Determination of structural and vibrational spectroscopic features of neutral and anion forms of dinicotinic acid by using NMR, infrared and Raman experimental methods combined with DFT and HF

    Science.gov (United States)

    Kose, E.; Bardak, F.; Atac, A.; Karabacak, M.; Cipiloglu, M. A.

    2013-10-01

    In this study; the experimental (NMR, infrared and Raman) and theoretical (HF and DFT) analysis of dinicotinic acid were presented. 1H and 13C NMR spectra were recorded in DMSO solution and chemical shifts were calculated by using the gauge-invariant atomic orbital (GIAO) method. The vibrational spectra of dinicotinic acid were recorded by FT-Raman and FT-IR spectra in the range of 4000-10 cm-1 and 4000-400 cm-1, respectively. To determine the most stable neutral conformer of molecule, the selected torsion angle was changed every 10° and molecular energy profile was calculated from 0° to 360°. The geometrical parameters and energies were obtained for all conformers form from density functional theory (DFT/B3LYP) and HF with 6-311++G(d,p) basis set calculations. However, the results of the most stable neutral and two anion forms (anion-1 and anion-2 forms) of dinicotinic acid are reported here. The complete assignments were performed on the basis of the total energy distribution (TED) of the vibrational wavenumbers, calculated with scaled quantum mechanics (SQM) method and PQS program.

  19. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of O-desmethyltramadol hydrochloride an active metabolite in tramadol - An analgesic drug

    Science.gov (United States)

    Arjunan, V.; Santhanam, R.; Marchewka, M. K.; Mohan, S.

    2014-03-01

    O-desmethyltramadol is one of the main metabolites of tramadol widely used clinically and has analgesic activity. The FTIR and FT-Raman spectra of O-desmethyl tramadol hydrochloride are recorded in the solid phase in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. Theoretical studies have been performed as its hydrochloride salt. The structure of the compound has been optimised with B3LYP method using 6-31G** and cc-pVDZ basis sets. The optimised bond length and bond angles are correlated with the X-ray data. The experimental wavenumbers were compared with the scaled vibrational frequencies determined by DFT methods. The IR and Raman intensities are determined with B3LYP method using cc-pVDZ and 6-31G(d,p) basic sets. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/cc-pVDZ method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of O-desmethyltramadol hydrochloride has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecule have been anlysed.

  20. Raman and ellipsometry spectroscopic analysis of graphene films grown directly on Si substrate via CVD technique for estimating the graphene atomic planes number

    Science.gov (United States)

    Al-Hazmi, F. S.; Beall, Gary W.; Al-Ghamdi, A. A.; Alshahrie, Ahmed; Shokr, F. S.; Mahmoud, Waleed E.

    2016-08-01

    Two reliable approaches for estimating the number of atomic planes of graphene films grown on Si substrate were demonstrated by Raman and ellipsometry spectroscopies. The first approach depends on the measurement of the ratio of the integrated Raman scattering intensity of the graphene G band to the optical phonon band of Si substrate (IG/ISi). The second approach belongs to ellipsometry measurement of the ratio of the amplitude of the reflected polarized light from the surface of the graphene films to the amplitude of reflected polarized light from the surface of the Si substrate (ΨG/ΨSi). These two approaches could efficiently recognize the number of atomic planes in the graphene films (1 ≤ n ≤ 10). The results were compared with atomic force microscopy (AFM) measurement and showed a linear regression with slope of 0.36 ± 0.01 nm/graphene layer. The Two approaches will open a new avenue to efficiently count the number of graphene layers during the preparation process.

  1. Raman spectroscopic studies on single crystals of the iron-based superconductor SmFeAsO{sub 1-x}F{sub x}

    Energy Technology Data Exchange (ETDEWEB)

    Jursic, Ivan; Schoenes, Joachim [Technische Universitaet Braunschweig, Institut fuer Physik der Kondensierten Materie, 38106 Braunschweig (Germany); Bukowski, Zbigniew; Karpinski, Janusz [ETH Zuerich, Laboratorium fuer Festkoerperphysik, 8093 Zuerich (Switzerland)

    2009-07-01

    The recent discovery of superconductivity in iron-based oxypnctides has led to a great interest in this new class of non-cuprate high-T{sub c} superconductors. Though theoretical work predicts a small electron-phonon coupling, which means that this should not be the driving mechanism for the observed T{sub c}'s in this class of material, the exact coupling mechanism is still under debate. We present Raman studies on superconducting SmFeAsO{sub 1-x}F{sub x} single crystals where the T{sub c} was determined by SQUID magnetometric measurements to be 34 K. At room temperature polarized measurements were performed to assign the phonon modes. Furthermore studies at different temperatures reaching from 5K to 300K were done to investigate the phonon behavior. The phonon frequencies shift with temperature and we investigate this shift in terms of electron-phonon coupling.

  2. Vibrational spectroscopic (FT-IR, FT-Raman, ¹H NMR and UV) investigations and computational study of 5-nitro-2-(4-nitrobenzyl) benzoxazole.

    Science.gov (United States)

    Bhagyasree, J B; Varghese, Hema Tresa; Panicker, C Yohannan; Samuel, Jadu; Van Alsenoy, Christian; Bolelli, Kayhan; Yildiz, Ilkay; Aki, Esin

    2013-02-01

    The optimized molecular structure, vibrational frequencies, corresponding vibrational assignments of 5-nitro-2-(4-nitrobenzyl) benzoxazole have been investigated experimentally and theoretically using Gaussian09 software package. Potential energy distribution of the normal modes of vibrations was done using GAR2PED program. The energy and oscillator strength calculated by time dependent density functional theory almost compliments with experimental findings. Gauge-including atomic orbital (1)H NMR chemical shifts calculations were carried out by using B3LYP functional with 6-31G basis set. The HOMO and LUMO analysis is used to determine the charge transfer within the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization have been analyzed using NBO analysis. MEP was performed by the DFT method and the predicted infrared intensities and Raman activities have also been reported. The calculated geometrical parameters are in agreement with that of similar derivatives.

  3. Micro-Raman and FT-IR spectroscopic studies of ceramic shards excavated from ancient Stratonikeia city at Eskihisar village in West-South Turkey

    Science.gov (United States)

    Bahçeli, Semiha; Güleç, Gamze; Erdoğan, Hasan; Söğüt, Bilal

    2016-02-01

    In this study, micro-Raman and Fourier transformed infrared (FT-IR) spectroscopies, X-ray diffraction (XRD) and scanning electron microscope with energy dispersive X-ray (SEM-EDX) were used to characterize the mineralogical structures of pigments of four ceramic fragments in which one of them belongs to Hellenistic period (1st - IVth century BC) and other three ceramic shards belong to Early Rome (IVth century BC- 1st century AD) excavated from Stratonikeia ancient city. In the results of investigations on these four ceramic fragments, the various phases were identified: quartz, kaolinite, albit (or Na-feldspar), calcite, anastase, hematite and magnetite. Furthermore, the obtained findings indicate that firing temperature is about 800-850 °C for all the shards.

  4. Molecular structure, spectroscopic characterization (FT-IR, FT-Raman, UV and NMR), HOMO and LUMO analysis of 3-ethynylthiophene with DFT quantum chemical calculations

    Science.gov (United States)

    Karabacak, Mehmet; Bilgili, Sibel; Mavis, Tugba; Eskici, Mustafa; Atac, Ahmet

    2013-11-01

    In this work, FT-IR, FT-Raman, UV and NMR spectra of 3-ethynylthiophene (3-ETP, C6H4S) were carried out by using density functional theory DFT/B3LYP method with the 6-311++G(d,p), 6-311+G(d,p), 6-311G(d,p), 6-31++G(d,p), 6-31+G(d,p), 6-31G(d,p) basis sets. FT-IR and FT-Raman spectra were recorded in the regions of 3500-400 cm-1 and 3500-50 cm-1, respectively. The geometrical parameters, energies and wavenumbers were obtained and the complete assignments of fundamental vibrations were performed on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method and PQS program. The 1H, 13C and HMQC (1H-13C correlation) NMR spectra in chloroform (CDCl3) were recorded and calculated. The UV spectrum of investigated compound were recorded in the region of 200-400 nm in ethanol solution. The electronic properties, such as excitation energies, absorption wavelengths, HOMO and LUMO energies were performed by DFT/B3LYP approach and the results were compared with experimental observations. The thermodynamic properties such zero-point vibrational energy, thermal energy, specific heat capacity, rotational constants, entropy, and dipole moment of the studied compound were calculated. As a result, the calculated results were compared with the observed data and found to be in good agreement.

  5. Raman and FTIR spectroscopic studies of 1-ethyl-3-methylimidazolium trifluoromethylsulfonate, its mixtures with water and the solvation of zinc ions.

    Science.gov (United States)

    Liu, Zhen; El Abedin, Sherif Zein; Endres, Frank

    2015-04-01

    In this paper we report on the interactions of the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethylsulfonate ([EMIm]TfO) with water and the solvation of zinc ions in neat [EMIm]TfO and [EMIm]TfO-water mixtures investigated by FTIR and Raman spectroscopy. The structures and physicochemical properties of the [EMIm]TfO-water mixtures are strongly dependent on the interaction between cations, anions, and water. The structure was changed from ionic-liquid-like to water-like solutions upon addition of water. In addition, zinc salts can precipitate in 0.2 M Zn(TfO)2/[EMIm]TfO upon addition of 10 % (v/v) water, presumably as a result of polarity change of the solution. The average coordination number of TfO(-) per zinc ion calculated from Raman spectra is 3.8 in neat [EMIm]TfO, indicating that [Zn(TfO)4](2-), and [Zn(TfO)3](-) complexes are present in the solution. However, in the presence of water, water interacts preferentially with the zinc ions, leading to aqueous zinc species. The solvation of zinc ions in 1-butyl-1-methylpyrrolidinium trifluoromethylsulfonate ([Py(1,4)]TfO) was also investigated. In [Py(1,4)]TfO, there are, on average, 4.5 TfO(-) anions coordinating each zinc ion, corresponding to the weak interaction between [Py(1,4)](+) cations and TfO(-) anions. The species present in [Py(1,4)]TfO are likely a mixture of [Zn(TfO)4](2-) and [Zn(TfO)5](3-). PMID:25630920

  6. Spectroscopic (FT-IR, FT-Raman, FT-NMR and UV-Vis) investigation on benzil dioxime using quantum computational methods

    Science.gov (United States)

    Bakkiyaraj, D.; Periandy, S.; Xavier, S.

    2016-03-01

    The spectral analysis of benzil dioxime is carried out using the FTIR, FT Raman, FT NMR and UV-Vis spectra of the compound with the help of quantum computations by density functional theories. The FT-IR (4000 - 400 cm-1) and FT-Raman (4000-100 cm-1) spectra are recorded in solid phase, the 1H and 13C NMR spectra in DMSO phase and the UV spectrum (200-400 nm) in ethanol phase. The different conformers of the compound and their minimum energies are studied by potential energy surface scan, using semi-empirical method PM6. The computed wavenumbers from different methods are scaled so as to agree with the experimental values and the scaling factors are reported. All the fundamental modes have been assigned based on the potential energy distribution (PED) values and the structure the molecule is analyzed interms of parameters like bond length, bond angle and dihedral angles predicted byB3LYP and CAM-B3LYP methods with cc-pVDZ basis sets. The values of dipole moment (μ), polarizability (α) and hyperpolarizability (β) of the molecule are reported, using which the non -linear optical property of the molecule is discussed. The HOMO-LUMO mappings are reported which reveals the different charge transfer possibilities within the molecule. The isotropic chemical shifts predicted for 1H and 13C atoms using gauge invariant atomic orbital (GIAO) theory show good agreement with experimental shifts and the same is discussed in comparison with atomic charges, predicted by Mullikan and APT charge analysis. NBO analysis is carried out to picture the probable electronic transitions in the molecule.

  7. Spectroscopic (FT-IR, FT-Raman, UV and NMR) investigation and NLO, HOMO-LUMO, NBO analysis of organic 2,4,5-trichloroaniline

    Science.gov (United States)

    Govindarajan, M.; Karabacak, M.; Periandy, S.; Tanuja, D.

    2012-11-01

    In this work, the experimental and theoretical study on the molecular structure and vibrational spectra of 2,4,5-trichloroaniline (C6H4NCl3, abbreviated as 2,4,5-TClA) were studied. The FT-IR and FT-Raman spectra were recorded. The molecular geometry and vibrational frequencies in the ground state were calculated by using the Hartree-Fock (HF) and density functional theory (DFT) methods (B3LYP) with 6-311++G(d,p) basis set. Comparison of the observed fundamental vibrational frequencies of 2,4,5-TClA with calculated results by HF and DFT indicates that B3LYP is superior to HF method for molecular vibrational problems. The difference between the observed and scaled wavenumber values of most of the fundamentals is very small. The theoretically predicted FT-IR and FT-Raman spectra of the title molecule have been constructed. A study on the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. Besides, molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and the first hyperpolarizability (β) values of the investigated molecule were computed using ab initio quantum mechanical calculations. The calculated results also show that the 2,4,5-TClA molecule may have microscopic nonlinear optical (NLO) behavior with non-zero values. Mulliken atomic charges of 2,4,5-TClA was calculated and compared with aniline and chlorobenzene molecules. The 13C nuclear magnetic resonance (NMR) chemical shifts of the molecule were calculated by the gauge independent atomic orbital (GIAO) method and compared with experimental results.

  8. Raman spectrum of asphaltene

    KAUST Repository

    Abdallah, Wael A.

    2012-11-05

    Asphaltenes extracted from seven different crude oils representing different geological formations from around the globe were analyzed using the Raman spectroscopic technique. Each spectrum is fitted with four main peaks using the Gaussian function. On the basis of D1 and G bands of the Raman spectrum, asphaltene indicated an ordered structure with the presence of boundary defected edges. The average aromatic sheet size of the asphaltene molecules is estimated within the range of 1.52-1.88 nm, which represents approximately seven to eight aromatic fused rings. This estimation is based on the integrated intensity of D1 and G bands, as proposed by Tunistra and Koenig. The results here are in perfect agreement with so many other used techniques and indicate the potential applicability of Raman measurements to determine the average aromatic ring size and its boundary. © 2012 American Chemical Society.

  9. Structure, infrared and Raman spectroscopic studies of newly synthetic AII(SbV0.50FeIII0.50)(PO4)2 (Adbnd Ba, Sr, Pb) phosphates with yavapaiite structure

    Science.gov (United States)

    Aatiq, Abderrahim; Tigha, My Rachid; Fakhreddine, Rachid; Bregiroux, Damien; Wallez, Gilles

    2016-08-01

    The synthesis and structural study of three new AII(SbV0.5FeIII0.5)(PO4)2 (Adbnd Ba, Sr, Pb) phosphates belonging to the Asbnd Sbsbnd Fesbnd Psbnd O system were reported here for the first time. Structures of [Ba], [Sr] and [Pb] compounds, obtained by solid state reaction in air atmosphere, were determined at room temperature from X-ray powder diffraction using the Rietveld method. BaII(SbV0.5FeIII0.5)(PO4)2 features the yavapaiite-type structure, with space group C2/m, Z = 2 and a = 8.1568(4) Å; b = 5.1996(3) Å c = 7.8290(4) Å; β = 94.53(1)°. AII(SbV0.5FeIII0.5)(PO4)2 (Adbnd Sr, Pb) compounds have a distorted yavapaiite structure with space group C2/c, Z = 4 and a = 16.5215(2) Å; b = 5.1891(1) Å c = 8.0489(1) Å; β = 115.70(1)° for [Sr]; a = 16.6925(2) Å; b = 5.1832(1) Å c = 8.1215(1) Å; β = 115.03(1)° for [Pb]. Raman and Infrared spectroscopic study was used to obtain further structural information about the nature of bonding in selected compositions.

  10. FT-Raman, FT-IR, UV spectroscopic, NBO and DFT quantum chemical study on the molecular structure, vibrational and electronic transitions of clopidogrel hydrogen sulfate form 1: A comparison to form 2

    Science.gov (United States)

    Srivastava, Anubha; Mishra, Rashmi; Tandon, Poonam; Bansal, A. K.

    2013-03-01

    Clopidogrel hydrogen sulfate (+)-(S)-(2-chlorophenyl)-6,7-dihydrothieno[3,2-c]pyridine-5(4H)-acetate sulfate (1:1), is a selective adenosine diphosphate (ADP) receptor antagonist often used in the treatment of coronary artery, peripheral vascular and cerebrovascular diseases. In the present communication, a comparative study of two polymorphic forms (forms 1 and 2) of clopidogrel hydrogen sulfate (CLP) has been reported. There is difference in conformation and intermolecular hydrogen bonding pattern of two forms. These differences are nicely reflected in the vibrational spectra. The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands of CLP form 1 are interpreted with the aid of structure optimizations and normal mode analysis based on ab initio HF and DFT method employing 6-311++G(d,p) basis. Polymorphism in CLP have been studied using various characterization tools like FT-Raman, FT-IR spectroscopy and DSC in combination with the quantum chemical calculations. UV-vis spectroscopic studies along with HOMO-LUMO analysis of both polymorphs were performed. The solvent effect calculated by TD-DFT/IEF-PCM/6-31G model results complements with the experimental findings. Stability of the molecule arising from hyper conjugative interactions and charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

  11. Raman-based imaging uncovers the effects of alginate hydrogel implants in spinal cord injury

    Science.gov (United States)

    Galli, Roberta; Tamosaityte, Sandra; Koch, Maria; Sitoci-Ficici, Kerim H.; Later, Robert; Uckermann, Ortrud; Beiermeister, Rudolf; Gelinsky, Michael; Schackert, Gabriele; Kirsch, Matthias; Koch, Edmund; Steiner, Gerald

    2015-07-01

    The treatment of spinal cord injury by using implants that provide a permissive environment for axonal growth is in the focus of the research for regenerative therapies. Here, Raman-based label-free techniques were applied for the characterization of morphochemical properties of surgically induced spinal cord injury in the rat that received an implant of soft unfunctionalized alginate hydrogel. Raman microspectroscopy followed by chemometrics allowed mapping the different degenerative areas, while multimodal multiphoton microscopy (e.g. the combination of coherent anti-Stokes Raman scattering (CARS), endogenous two-photon fluorescence and second harmonic generation on the same platform) enabled to address the morphochemistry of the tissue at cellular level. The regions of injury, characterized by demyelination and scarring, were retrieved and the distribution of key tissue components was evaluated by Raman mapping. The alginate hydrogel was detected in the lesion up to six months after implantation and had positive effects on the nervous tissue. For instance, multimodal multiphoton microscopy complemented the results of Raman mapping, providing the micromorphology of lipid-rich tissue structures by CARS and enabling to discern lipid-rich regions that contained myelinated axons from degenerative regions characterized by myelin fragmentation and presence of foam cells. These findings demonstrate that Raman-based imaging methods provide useful information for the evaluation of alginate implant effects and have therefore the potential to contribute to new strategies for monitoring degenerative and regenerative processes induced in SCI, thereby improving the effectiveness of therapies.

  12. Simultaneous time and frequency detection in femtosecond coherent Raman spectroscopy. I. Theory and model calculations

    Science.gov (United States)

    Urbanek, Diana C.; Berg, Mark A.

    2007-07-01

    For coherent Raman spectroscopies, common femtosecond pulses often lie in an intermediate regime: their bandwidth is too wide for measurements in the frequency domain, but their temporal width is too broad for homodyne measurements in the time domain. A recent paper [S. Nath et al., Phys. Rev. Lett. 97, 267401 (2006)] showed that complete Raman spectra can be recovered from intermediate length pulses by using simultaneous time and frequency detection (TFD). Heterodyne detection and a phase-stable local oscillator at the anti-Stokes frequency are not needed with TFD. This paper examines the theory of TFD Raman in more detail; a companion paper tests the results on experimental data. Model calculations illustrate how information on the Raman spectrum is transferred from the frequency domain to the time domain as the pulse width shortens. When data are collected in both dimensions, the Raman spectrum is completely determined to high resolution, regardless of the probe pulse width. The loss of resolution in many femtosecond coherent Raman experiments is due to the restriction to one-dimensional data collection, rather than due to a fundamental restriction based on the pulse width.

  13. Vibrational [FT-IR, FT-Raman] analysis, NMR and mass - Spectroscopic investigation on 3,6-Dimethylphenanthrene using computational calculation

    Science.gov (United States)

    Manzoor Ali, M.; George, Gene; Ramalingam, S.; Periandy, S.; Gokulakrishnan, V.

    2015-11-01

    In this research work, in order to the vibrational, physical and chemical properties, a thorough investigation has been made by recording FT-IR, FT-Raman, Mass and 13C and 1H NMR spectra of pharmaceutically important compound; 3,6-Dimethylphenanthrene. The altered geometrical parameters of Phenanthrene due to the addition of methyl groups have been calculated using HF and DFT (B3LYP and B3PW91) methods with 6-31++G(d,p) and 6-311++G(d,p) basis sets and the discussion are made on their corresponding results. The alternation of the vibrational pattern of the molecule due to the injection of the substitutions; CH3 is investigated. The keen observation is made over the excitations between the electronic energy levels of the molecule which lead to the study of electronic properties. The alternation of distribution of Mulliken charges after the formation of present molecule has been correlated with the vibrational pattern of the molecular bonds. The charge transformation over the frontier molecular orbitals between the ligand and rings has been studied. The cause of the linear and non linear optical activity of the molecule is interpreted in detail from the average Polarizability first order diagonal hyperpolarizability calculations. The variation of thermodynamic properties; heat capacity, entropy, and enthalpy of the present compound at different temperatures are calculated using NIST thermodynamical function program and interpreted.

  14. Spectroscopic (FT-IR, FT-Raman) and quantum mechanical studies of 3t-pentyl-2r,6c-diphenylpiperidin-4-one thiosemicarbazone

    Science.gov (United States)

    Savithiri, S.; Arockia doss, M.; Rajarajan, G.; Thanikachalam, V.; Bharanidharan, S.; Saleem, H.

    2015-02-01

    In this study, the molecular structure and vibrational spectra of 3t-pentyl2r,6c-diphenylpiperidin-4-one thiosemicarbazone (PDPOTSC) were studied. The ground-state molecular geometry was ascertained by using the density functional theory (DFT)/B3LYP method using 6-31++G(d,p) as a basis set. The vibrational (FT-IR and FT-Raman) spectra of PDPOTSC were computed using DFT/B3LYP and HF methods with 6-31++G(d,p) basis set. The fundamental vibrations were assigned on the basis of the total energy distribution (TED ⩾ 10%) of the vibrational modes, calculated with scaled quantum mechanics (SQM) methods PQS program. The electrical dipole moment (μ) and first hyperpolarizability (βo) values have been computed using DFT/B3LYP and HF methods. The calculated result (βo) shows that the title molecule might have nonlinear optical (NLO) behavior. Atomic charges of C, N, S and molecular electrostatic potential (MEP) were calculated using B3LYP/6-31G++(d,p). The HOMO-LUMO energies were calculated and natural bonding orbital (NBO) analysis has also been carried out.

  15. Molecular structure, spectroscopic (FT-IR, FT-Raman) studies and first-order molecular hyperpolarizabilities, HOMO-LUMO, NBO analysis of 2-hydroxy-p-toluic acid.

    Science.gov (United States)

    Balachandran, V; Nataraj, A; Karthick, T

    2013-03-01

    FT-Raman and FT-IR spectra for 2-hydroxy-p-toluic acid molecule had been recorded in the regions 3500-100 cm(-1) and 4000-400 cm(-1), respectively. Vibrational frequencies have been calculated in optimum state by employing density functional theory (DFT) and Hartree Fock (HF) methods with 6-311++G(d,p) basis set in monomeric form. SQM force fields have also been used to calculate potential energy distributions in order to make conspicuous vibrational assignments. Optimized geometries of the molecule had been interpreted and compared. The electric dipole moment and first hyperpolarizability values of the investigated molecule were computed using ab initio and DFT calculations. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Stability of the molecule arising from hyper conjugative interactions, charge delocalization has been analyzed using natural bond analysis. The results show that charge in electron density (ED) in the σ(*) antibonding orbitals and E((2)) energies confirms the occurrence of ICT within the molecule. PMID:23266684

  16. Determination of diffusion coefficients of carbon dioxide in water between 268 and 473 K in a high-pressure capillary optical cell with in situ Raman spectroscopic measurements

    Science.gov (United States)

    Lu, Wanjun; Guo, Huirong; Chou, I.-Ming; Burruss, R.C.; Li, Lanlan

    2013-01-01

    Accurate values of diffusion coefficients for carbon dioxide in water and brine at reservoir conditions are essential to our understanding of transport behavior of carbon dioxide in subsurface pore space. However, the experimental data are limited to conditions at low temperatures and pressures. In this study, diffusive transfer of carbon dioxide in water at pressures up to 45 MPa and temperatures from 268 to 473 K was observed within an optical capillary cell via time-dependent Raman spectroscopy. Diffusion coefficients were estimated by the least-squares method for the measured variations in carbon dioxide concentration in the cell at various sample positions and time. At the constant pressure of 20 MPa, the measured diffusion coefficients of carbon dioxide in water increase with increasing temperature from 268 to 473 K. The relationship between diffusion coefficient of carbon dioxide in water [D(CO2) in m2/s] and temperature (T in K) was derived with Speedy–Angell power-law approach as: D(CO2)=D0[T/Ts-1]m where D0 = 13.942 × 10−9 m2/s, Ts = 227.0 K, and m = 1.7094. At constant temperature, diffusion coefficients of carbon dioxide in water decrease with pressure increase. However, this pressure effect is rather small (within a few percent).

  17. Shedding new light on the molecular architecture of oocytes using a combination of synchrotron Fourier transform-infrared and Raman spectroscopic mapping.

    Science.gov (United States)

    Wood, Bayden R; Chernenko, Tatyana; Matthäus, Christian; Diem, Max; Chong, Connie; Bernhard, Uditha; Jene, Cassandra; Brandli, Alice A; McNaughton, Don; Tobin, Mark J; Trounson, Alan; Lacham-Kaplan, Orly

    2008-12-01

    Synchrotron Fourier transform-infrared (FT-IR) and Raman microspectroscopy were applied to investigate changes in the molecular architecture of mouse oocytes and demonstrate the overall morphology of the maturing oocyte. Here we show that differences were identified between immature mouse oocytes at the germinal vesicle (GV) and mature metaphase II (MII) stage when using this technology, without the introduction of any extrinsic markers, labels, or dyes. GV mouse oocytes were found to have a small, centrally located lipid deposit and another larger polar deposit of similar composition. MII oocytes have very large, centrally located lipid deposits. Each lipid deposit for both cell types contains an inner and outer lipid environment that differs in composition. To assess interoocyte variability, line scans were recorded across the diameter of the oocytes and compared from three independent trials (GV, n = 91; MII, n = 172), and the data were analyzed with principal component analysis (PCA). The average spectra and PCA loading plots show distinct and reproducible changes in the CH stretching region that can be used as molecular maturation markers. The method paves the way for developing an independent assay to assess oocyte status during maturation providing new insights into lipid distribution at the single cell level.

  18. Transcutaneous in vivo Raman spectroscopic studies in a mouse model: evaluation of changes in the breast associated with pregnancy and lactation

    Science.gov (United States)

    Bhattacharjee, Tanmoy; Maru, Girish; Ingle, Arvind; Krishna, C. Murali

    2013-04-01

    Raman spectroscopy (RS) has been extensively explored as an alternative diagnostic tool for breast cancer. This can be attributed to its sensitivity to malignancy-associated biochemical changes. However, biochemical changes due to nonmalignant conditions like benign lesions, inflammatory diseases, aging, menstrual cycle, pregnancy, and lactation may act as confounding factors in diagnosis of breast cancer. Therefore, in this study, the efficacy of RS to classify pregnancy and lactation-associated changes as well as its effect on breast tumor diagnosis was evaluated. Since such studies are difficult in human subjects, a mouse model was used. Spectra were recorded transcutaneously from the breast region of six Swiss bare mice postmating, during pregnancy, and during lactation. Data were analyzed using multivariate statistical tool Principal Component-Linear Discriminant Analysis. Results suggest that RS can differentiate breasts of pregnant/lactating mice from those of normal mice, the classification efficiencies being 100%, 60%, and 88% for normal, pregnant, and lactating mice, respectively. Frank breast tumors could be classified with 97.5% efficiency, suggesting that these physiological changes do not affect the ability of RS to detect breast tumors.

  19. High pressure Raman spectroscopic study of the effects of n-ethylamines and water on the 2-nitropropane/Nitric acid system

    Energy Technology Data Exchange (ETDEWEB)

    Gobin, Cedric; Petitet, Jean Pierre [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions, CNRS, Institut Galilee, Universite Paris XIII, 99 av. J-B Clement, 93430 Villetaneuse (France)

    2005-12-01

    High pressure Raman spectroscopy measurements in a diamond anvil cell (0-10 GPa) on 2-nitropropane/nitric acid/X (X=triethylamine, diethylamine, and water) ternary systems and 2-nitropropane/nitric acid/water/Y (Y=triethylamine and diethylamine) quaternary systems are reported. The modifications of the chemical behavior of the 2-nitropropane/nitric acid model system, induced by the presence of triethylamine, diethylamine, and/or water, were studied at ambient and high pressure. At ambient pressure, the ionization of the nitric acid has been observed with each of the additives. Moreover, in the case of ethylamines, new peaks have been observed and the hypothesis of a 2-nitropropane/ethylamine complex is advanced. At high pressure, the decomposition of the 2-nitropropane/nitric acid system, with an oxygen balance near zero, has been observed only in presence of triethylamine. The role of each additive to the 2-nitropropane/nitric acid system in the modification of the respective reducing and oxidizing character of the components, and in the reactivity of the system, is discussed. Several hypotheses are advanced concerning the sensitizing effect of the additives on the 2-nitropropane/nitric acid system. (Abstract Copyright [2005], Wiley Periodicals, Inc.)

  20. Nonlinear microscopy, infrared, and Raman microspectroscopy for brain tumor analysis

    Science.gov (United States)

    Meyer, Tobias; Bergner, Norbert; Bielecki, Christiane; Krafft, Christoph; Akimov, Denis; Romeike, Bernd F. M.; Reichart, Rupert; Kalff, Rolf; Dietzek, Benjamin; Popp, Jürgen

    2011-02-01

    Contemporary brain tumor research focuses on two challenges: First, tumor typing and grading by analyzing excised tissue is of utmost importance for choosing a therapy. Second, for prognostication the tumor has to be removed as completely as possible. Nowadays, histopathology of excised tissue using haematoxylin-eosine staining is the gold standard for the definitive diagnosis of surgical pathology specimens. However, it is neither applicable in vivo, nor does it allow for precise tumor typing in those cases when only nonrepresentative specimens are procured. Infrared and Raman spectroscopy allow for very precise cancer analysis due to their molecular specificity, while nonlinear microscopy is a suitable tool for rapid imaging of large tissue sections. Here, unstained samples from the brain of a domestic pig have been investigated by a multimodal nonlinear imaging approach combining coherent anti-Stokes Raman scattering, second harmonic generation, and two photon excited fluorescence microscopy. Furthermore, a brain tumor specimen was additionally analyzed by linear Raman and Fourier transform infrared imaging for a detailed assessment of the tissue types that is required for classification and to validate the multimodal imaging approach. Hence label-free vibrational microspectroscopic imaging is a promising tool for fast and precise in vivo diagnostics of brain tumors.

  1. Raman spectroscopy as a tool for reagent free estimation

    CERN Document Server

    Kumar, S

    2014-01-01

    We present results of Raman spectroscopic studies of urine to determine the suitability of near-infrared Raman spectroscopy for quantitative estimation of urinary urea. The Raman spectra were acquired from the urine samples with an inbuilt Raman spectroscopy setup that employs a 785-nm diode laser as the Raman excitation source. A multivariate algorithm based on partial least square (PLS) regression was developed to predict the concentration of urea depending on the measured sets of Raman spectra and the reference urea concentration. The computed results shows that Raman spectroscopy in amalgamation with PLS-based multivariate chemometric algorithm can detect urea in urine samples with an accuracy of >90 %.

  2. Raman Spectroscopy for Clinical Oncology

    Directory of Open Access Journals (Sweden)

    Michael B. Fenn

    2011-01-01

    Full Text Available Cancer is one of the leading causes of death throughout the world. Advancements in early and improved diagnosis could help prevent a significant number of these deaths. Raman spectroscopy is a vibrational spectroscopic technique which has received considerable attention recently with regards to applications in clinical oncology. Raman spectroscopy has the potential not only to improve diagnosis of cancer but also to advance the treatment of cancer. A number of studies have investigated Raman spectroscopy for its potential to improve diagnosis and treatment of a wide variety of cancers. In this paper the most recent advances in dispersive Raman spectroscopy, which have demonstrated promising leads to real world application for clinical oncology are reviewed. The application of Raman spectroscopy to breast, brain, skin, cervical, gastrointestinal, oral, and lung cancers is reviewed as well as a special focus on the data analysis techniques, which have been employed in the studies.

  3. STRUCTURE FEATURES OF THE SODIUM-GERMANATE GLASSES DOPED WITH YTTERBIUM ERBIUM RETRIEVED FROM RAMAN SPECTROSCOPY

    Directory of Open Access Journals (Sweden)

    I. M. Sevastianova

    2016-09-01

    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.

  4. Infrared and Raman spectroscopic methods for characterization of Taxus baccata L.--Improved taxane isolation by accelerated quality control and process surveillance.

    Science.gov (United States)

    Gudi, Gennadi; Krähmer, Andrea; Koudous, Iraj; Strube, Jochen; Schulz, Hartwig

    2015-10-01

    Different yew species contain poisonous taxane alkaloids which serve as resources for semi-synthesis of anticancer drugs. The highly variable amounts of taxanes demand new methods for fast characterization of the raw plant material and the isolation of the target structures during phyto extraction. For that purpose, applicability of different vibrational spectroscopy methods in goods receipt of raw plant material and in process control was investigated and demonstrated in online tracking isolation and purification of the target taxane 10-deacetylbaccatin III (10-DAB) during solvent extraction. Applying near (NIRS) and mid infrared spectroscopy (IRS) the amount of botanical impurities in mixed samples of two different yew species (R(2)=0.993), the leave-to-wood ratio for Taxus baccata material (R(2)=0.94) and moisture in dried yew needles (R(2)=0.997) can be quantified. By partial least square analysis (PCA) needles of different Coniferales species were successfully discriminated by Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy (ATR-FT-IR). The analytical potential of ATR-FT-IR and Fourier Transform-Raman Spectroscopy (FT-RS) in process control of extraction and purification of taxanes is demonstrated for determination of the water content in methanolic yew extracts (R(2)=0.999) and for quantification of 10-DAB (R(2)=0.98) on a highly sophisticated level. The decrease of 10-DAB in the plant tissue during extraction was successfully visualized by FT-IR imaging of thin cross sections providing new perspectives for process control and design. PMID:26078126

  5. The effect of an anti-hydrogen bond on Fermi resonance:A Raman spectroscopic study of the Fermi doublet v1-v12 of liquid pyridine

    Institute of Scientific and Technical Information of China (English)

    Li Dong-Fei; Gao Shu-Qin; Sun Cheng-Lin; Li Zuo-Wei

    2012-01-01

    The effects of an anti-hydrogen bond on the v1-v12 Fermi resonance (FR) of pyridine are experimentally investigated by using Raman scattering spectroscopy.Three systems,pyridine/water,pyridine/formamide,and pyridine/carbon tetrachloride,provide varying degrees of strength for the diluent-pyridine anti-hydrogen bond complex.Water forms a stronger anti-hydrogen bond with pyridine than with formamide,and in the case of adding non-polar solvent carbon tetrachloride,which is neither a hydrogen bond donor nor an acceptor and incapable of forming a hydrogen bond with pyridine,the intermolecular distance of pyridine will increase and the interaction of pyridine molecules will reduce.The dilution studies are performed on the three systems.Comparing with the values of the Fermi coupling coefficient W of the ring breathing mode v1 and triangle mode v12 of pyridine at different volume concentrations,which are calculated according to the Bertran equations,in three systems,we find that the solution with the strongest anti-hydrogen bond,water,shows the fastest change in thev1-v12 Fermi coupling coefficient W with the volume concentration varying,followed by the formamide and carbon tetrachloride solutions.These results suggest that the stronger anti-hydrogen bond-forming effect will cause a greater reduction in the strength of the v1-v12 FR of pyridine.According to the mechanism of the formation of an anti-hydrogen bond in the complexes and the FR theory,a qualitative explanation for the anti-hydrogen bond effect in reducing the strength of the v1 - v12 FR of pyridine is given.

  6. Molecular structure, electronic properties, NLO, NBO analysis and spectroscopic characterization of Gabapentin with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations.

    Science.gov (United States)

    Sinha, Leena; Karabacak, Mehmet; Narayan, V; Cinar, Mehmet; Prasad, Onkar

    2013-05-15

    Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated. PMID:23545435

  7. Conformational analysis, spectroscopic study (FT-IR, FT-Raman, UV, 1H and 13C NMR), molecular orbital energy and NLO properties of 5-iodosalicylic acid

    Science.gov (United States)

    Karaca, Caglar; Atac, Ahmet; Karabacak, Mehmet

    2015-02-01

    In this study, 5-iodosalicylic acid (5-ISA, C7H5IO3) is structurally characterized by FT-IR, FT-Raman, NMR and UV spectroscopies. There are eight conformers, Cn, n = 1-8 for this molecule therefore the molecular geometry for these eight conformers in the ground state are calculated by using the ab-initio density functional theory (DFT) B3LYP method approach with the aug-cc-pVDZ-PP basis set for iodine and the aug-cc-pVDZ basis set for the other elements. The computational results identified that the most stable conformer of 5-ISA is the C1 form. The vibrational spectra are calculated DFT method invoking the same basis sets and fundamental vibrations are assigned on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method with PQS program. Total density of state (TDOS) and partial density of state (PDOS) and also overlap population density of state (COOP or OPDOS) diagrams analysis for C1 conformer were calculated using the same method. The energy and oscillator strength are calculated by time-dependent density functional theory (TD-DFT) results complement with the experimental findings. Besides, charge transfer occurring in the molecule between HOMO and LUMO energies, frontier energy gap, molecular electrostatic potential (MEP) are calculated and presented. The NMR chemical shifts (1H and 13C) spectra are recorded and calculated using the gauge independent atomic orbital (GIAO) method. Mulliken atomic charges of the title molecule are also calculated, interpreted and compared with salicylic acid. The optimized bond lengths, bond angles and calculated NMR and UV, vibrational wavenumbers showed the best agreement with the experimental results.

  8. Effects of LED or laser phototherapy on bone defects grafted with MTA and irradiated with laser or LED light: a comparative Raman spectroscopic study

    Science.gov (United States)

    Pinheiro, Antonio L. B.; Soares, Luiz G. P.; Barbosa, Artur Felipe S.; Silveira, Landulfo, Jr.

    2012-03-01

    We studied peaks of calcium hydroxyapatite - CHA on defects grafted with MTA, treated or not with Light Emitting Diode - LED or IR Laser. 54 rats were divided in 6 groups each subdivided into 3 subgroups (15,21,30d). LED (λ850 +/- 10nm) or IR Laser (λ850 nm) was applied over (LED) or in 4 points around the defect at 48 h intervals for 15 days. Raman readings were taken at the surface of the defect. The smaller overall intensity of the peak was found in Group MTA + Laser (1510.2 +/- 274.1) and the highest on Group LED (2322 +/- 715). There were no statistically significant differences between non-irradiated subjects on regards the CHA peaks. On the other hand, there were statistically significant differences between the Group Clot and LED, Clot and Laser, and Clot and MTA + Laser (p =0.01, p = 0.02, p = 0.003). There were no significant differences between Group MTA and MTA + LED (p=0.2) but significant differences were seen between Groups MTA and MTA + Laser (p=0.01). Significant differences were also observed between Groups LED and Laser (p MTA + LED and MTA + Laser (p=0.009). MTA, due to its characteristics, seemed to be directly affected by the light. However, the use of either phototherapy positively affected bone healing similarly as observed on different studies using other biomaterials. The overall analysis of our results indicated that the use of either light source resulted in a better, more advanced, and of quality bone repair.

  9. Molecular structure, electronic properties, NLO, NBO analysis and spectroscopic characterization of Gabapentin with experimental (FT-IR and FT-Raman) techniques and quantum chemical calculations

    Science.gov (United States)

    Sinha, Leena; Karabacak, Mehmet; Narayan, V.; Cinar, Mehmet; Prasad, Onkar

    2013-05-01

    Gabapentin (GP), structurally related to the neurotransmitter GABA (gamma-aminobutyric acid), mimics the activity of GABA and is also widely used in neurology for the treatment of peripheral neuropathic pain. It exists in zwitterionic form in solid state. The present communication deals with the quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of GP using density functional (DFT/B3LYP) method with 6-311++G(d,p) basis set. In view of the fact that amino acids exist as zwitterions as well as in the neutral form depending on the environment (solvent, pH, etc.), molecular properties of both the zwitterionic and neutral form of GP have been analyzed. The fundamental vibrational wavenumbers as well as their intensities were calculated and compared with experimental FT-IR and FT-Raman spectra. The fundamental assignments were done on the basis of the total energy distribution (TED) of the vibrational modes, calculated with scaled quantum mechanical (SQM) method. The electric dipole moment, polarizability and the first hyperpolarizability values of the GP have been calculated at the same level of theory and basis set. The nonlinear optical (NLO) behavior of zwitterionic and neutral form has been compared. Stability of the molecule arising from hyper-conjugative interactions and charge delocalization has been analyzed using natural bond orbital analysis. Ultraviolet-visible (UV-Vis) spectrum of the title molecule has also been calculated using TD-DFT method. The thermodynamic properties of both the zwitterionic and neutral form of GP at different temperatures have been calculated.

  10. The Impact of Array Detectors on Raman Spectroscopy

    Science.gov (United States)

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

    2007-01-01

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

  11. Monitoring intra-cellular lipid metabolism in macrophages by Raman- and CARS-microscopy

    Science.gov (United States)

    Matthäus, Christian; Bergner, Gero; Krafft, Christoph; Dietzek, Benjamin; Lorkowski, Stefan; Popp, Jürgen

    2010-04-01

    Monocyte-derived macrophages play a key role in lipid metabolism in vessel wall tissues. Macrophages can take up lipids by various mechanisms. As phagocytes, macrophages are important for the decomposition of lipid plaques within arterial walls that contribute to arteriosclerosis. Of special interest are uptake dynamics and intra-cellular fate of different individual types of lipids as, for example, fatty acids, triglycerides or free and esterified cholesterol. Here we utilize Raman microscopy to image the metabolism of such lipids and follow subsequent storage or degradation patterns. The combination of optical microscopy with Raman spectroscopy allows visualization at the diffraction limit of the employed laser light and biochemical characterization through the associated spectral information. Relatively long measuring times, due to the weakness of Raman scattering can be overcome by non-linear effects such as coherent anti-Stokes Raman scattering (CARS). With this contribution we introduce first results to monitor the incorporation of lipid components into individual cells employing Raman and CARS microscopy.

  12. Inflammation-related alterations of lipids after spinal cord injury revealed by Raman spectroscopy

    Science.gov (United States)

    Tamosaityte, Sandra; Galli, Roberta; Uckermann, Ortrud; Sitoci-Ficici, Kerim H.; Koch, Maria; Later, Robert; Schackert, Gabriele; Koch, Edmund; Steiner, Gerald; Kirsch, Matthias

    2016-06-01

    Spinal cord injury (SCI) triggers several lipid alterations in nervous tissue. It is characterized by extensive demyelination and the inflammatory response leads to accumulation of activated microglia/macrophages, which often transform into foam cells by accumulation of lipid droplets after engulfment of the damaged myelin sheaths. Using an experimental rat model, Raman microspectroscopy was applied to retrieve the modifications of the lipid distribution following SCI. Coherent anti-Stokes Raman scattering (CARS) and endogenous two-photon fluorescence (TPEF) microscopies were used for the detection of lipid-laden inflammatory cells. The Raman mapping of CH2 deformation mode intensity at 1440 cm-1 retrieved the lipid-depleted injury core. Preserved white matter and inflammatory regions with myelin fragmentation and foam cells were localized by specifically addressing the distribution of esterified lipids, i.e., by mapping the intensity of the carbonyl Raman band at 1743 cm-1, and were in agreement with CARS/TPEF microscopy. Principal component analysis revealed that the inflammatory regions are notably rich in saturated fatty acids. Therefore, Raman spectroscopy enabled to specifically detect inflammation after SCI and myelin degradation products.

  13. Raman Spectroscopy of Deinococcus Radiodurans and β-Carotene on a Mineral Background

    Science.gov (United States)

    Hooijschuur, J. H.; Davies, G. R.; Ariese, F.

    2014-06-01

    “Is there life on other planets?” is one of the key questions in space exploration. Resonance Raman (RRS), Time Resolved Raman (TRRS) and Spatially Offset Raman (SORS) are Raman spectroscopic tools to find microorganisms hidden in minerals.

  14. Surface-Enhanced Raman Scattering Physics and Applications

    CERN Document Server

    Kneipp, Katrin; Kneipp, Harald

    2006-01-01

    Almost 30 years after the first reports on surface-enhanced Raman signals, the phenomenon of surface-enhanced Raman scattering (SERS) is now well established. Yet, explaining the enhancement of a spectroscopic signal by fouteen orders of magnitude continues to attract the attention of physicists and chemists alike. And, at the same time and rapidly growing, SERS is becoming a very useful spectroscopic tool with exciting applications in many fields. SERS gained particular interest after single-molecule Raman spectroscopy had been demonstrated. This bookl summarizes and discusses present theoretical approaches that explain the phenomenon of SERS and reports on new and exciting experiments and applications of the fascinating spectroscopic effect.

  15. Raman facility

    Data.gov (United States)

    Federal Laboratory Consortium — Raman scattering is a powerful light scattering technique used to diagnose the internal structure of molecules and crystals. In a light scattering experiment, light...

  16. 基于SERS光谱的银溶胶溶液中腺嘌呤的定量分析%Quantitative Analysis with Adenine in Silver Colloidal Sol by Surface-enhanced Raman Scattering Spectroscopic Technique

    Institute of Scientific and Technical Information of China (English)

    冯小平; 曹晓卫; 汪佳俐; 李玲; 张志学

    2012-01-01

    Surface-enhanced Raman scattering (SERS) spectroscopic technique was used to perform quantitative analyses with adenine, an important basic group from nucleic acid, by using silver colloidal sol as the SERS substrate. Sodium polyacrylate was added into the silver colloidal sol in order to improve its stability. In addition, during different SERS measurements, pyridine was used an internal standard to eliminate the impact of the variations in laser power, optical alignment and focusing on the SERS signal intensity of the an-alyte. It reveals that a good linear relationship is presented between the concentration of adenine and the characteristic SERS signal intensity ratio of the analyte adenine (733 cm-1) to the internal standard pyridine (1003 cm-1) in the range of 1× 10-4~1× 10-3mol ·L-1.%碱基是构成核酸的物质基础.碱基的含量分析对于生物体的生理活动及新陈代谢过程研究具有重要意义.本文利用表面增强拉曼散射(SERS)光谱技术研究了腺嘌呤在相对稳定的银溶胶溶液中的SERS光谱信号强度与浓度的定量关系.研究表明添加聚合物作为稳定剂的银溶胶具有良好的稳定性.进一步研究表明,在1×10-4~1×10-2mol·L-1的浓度范围内,以吡啶作为内标,分析物腺嘌呤与内标物特征谱峰强度之比与腺嘌呤的浓度之间呈现良好的线性关系.

  17. Dramatic Raman Gain Suppression in the Vicinity of the Zero Dispersion Point in Gas-Filled Hollow-Core Photonic Crystal Fiber

    CERN Document Server

    Bauerschmidt, Sebastian T; Russell, Philip St J

    2015-01-01

    In 1964 Bloembergen and Shen predicted that Raman gain could be suppressed if the rates of phonon creation and annihilation (by inelastic scattering) exactly balance. This is only possible if the momentum required for each process is identical, i.e., phonon coherence waves created by pump-to-Stokes scattering are identical to those annihilated in pump-to-anti-Stokes scattering. In bulk gas cells, this can only be achieved over limited interaction lengths at an oblique angle to the pump axis. Here we report a simple system that provides dramatic Raman gain suppression over long collinear path-lengths in hydrogen. It consists of a gas-filled hollow-core photonic crystal fiber whose zero dispersion point is pressure-adjusted to lie close to the pump laser wavelength. At a certain precise pressure, generation of Stokes light in the fundamental mode is completely suppressed, allowing other much weaker nonlinear processes to be explored.

  18. Integrated coherent Raman scattering and multiphoton microscopy for label-free imaging of the dentin in the tooth

    Science.gov (United States)

    Wang, Zi; Zheng, Wei; Lin, Jian; Hsu, Chin-Ying; Huang, Zhiwei

    2014-02-01

    We report the implementation of a unique multimodal nonlinear optical microscopy (i.e., coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG), third harmonic generation (THG) and two photon excitation fluorescence (TPEF)) platform for label-free imaging of dentin. A picosecond tunable laser together with an OPO is used as the excitation source for simultaneously multimodal imaging. CARS shows similar information as TPEF in dentin, but it has a higher sectioning performance than TPEF and thus it is a good alternative for TPEF. Microtubule structure is revealed nearby dentin enamel junction (DEJ) from the multimodal images. This work demonstrates that combining different nonlinear optical imaging modalities can provide new insights into the understanding of morphological structures and biochemical/biomolecular distributions of the dentine without the need of labeling.

  19. Spectroscopic studies (FTIR, FT-Raman and UV), potential energy surface scan, normal coordinate analysis and NBO analysis of (2R,3R,4R,5S)-1-(2-hydroxyethyl)-2-(hydroxymethyl) piperidine-3,4,5-triol by DFT methods.

    Science.gov (United States)

    Isac Paulraj, E; Muthu, S

    2013-05-01

    This work presents the characterization of (2R,3R,4R,5S)-1-(2-hydroxyethyl)-2-(hydroxymethyl)piperidine-3,4,5-triol (abbreviated as HEHMPT) by quantum chemical calculations and spectral techniques. The spectroscopic properties were investigated by FT-IR, FT-Raman and UV-Vis techniques. The FT-IR spectrum (4000-400 cm(-1)) and FT-Raman spectrum (4000-100 cm(-1)) in solid phase was recorded for HEHMPT. The UV-Vis absorption spectrum of the HEHMPT that dissolved in water was recorded in the range of 100-400 nm. The structural and spectroscopic data of the molecule were obtained from B3LYP and M06-2X with 6-31G(d,p) basis set calculations. The theoretical wavenumbers were scaled and compared with experimental FT-IR and FT-Raman spectra. The complete assignments were performed on the basis of the normal co-ordinate analysis (NCA), experimental results and potential energy distribution (PED) of the vibrational modes, calculated with scaled quantum mechanics (SQM) method, interpreted in terms of fundamental modes. The stable geometry of the compound has been determined from the potential energy surface scan. The stability of molecule has been analyzed by NBO analysis. The molecule orbital contributions were studied by using the total (TDOS), partial (PDOS), and overlap population (OPDOS) density of states. The electronic properties like UV spectral analysis and HOMO-LUMO energies were reported. The calculated HOMO and LUMO energies shows that charge transfer interactions taking place within the molecule. Mulliken population analysis on atomic charges is also calculated. PMID:23454843

  20. Applications of Raman Spectroscopy to Virology and Microbial Analysis

    Science.gov (United States)

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

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

  1. Coherent Raman scattering microscopy for label-free imaging of live amphioxus

    Science.gov (United States)

    Yu, Zhilong; Chen, Tao; Zhang, Xiannian; Shen, Jie; Chen, Junyuan; Huang, Yanyi

    2012-03-01

    The existence of notochord distinguishes chordates from other phyla. Amphioxus is the only animal that keeps notochord during the whole life. Notochord is a unique organ for amphioxus, with its vertically arranged muscular notochordal plates, which is different from notochords in embryos of other chordates. We use stimulated Raman scattering (SRS) microscopy as a non-invasive technique to image the chemical components in amphioxus notochord. SRS provides chemical specificity as spontaneous Raman does and offers a higher sensitivity for fast acquisition. Unlike coherent anti- Stokes Raman scattering (CARS) microscopy, SRS microscopy doesn't have non-resonant background and can better differentiate different components in the specimen. We verify that the notochord is a protein-rich organ, which agrees well with the result of conventional staining methods. Detailed structures in notochordal plates and notochordal sheath are revealed by SRS microscopy with diffraction limited resolution. Our experiment shows that SRS microscopy is an excellent imaging tool for biochemical research with its intrinsic chemical selectivity, high spatiotemporal resolution and native 3D optical sectioning ability.

  2. Integrated optical modules for miniature raman spectroscopy devices

    OpenAIRE

    Çivitci, Fehmi

    2014-01-01

    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 advantages. A traditional Raman measurement system is a complex setup, whose usage is limited due to its bulky and expensive components. If it would be possible to achieve a miniature Raman spectroscopic sys...

  3. Use of rotational Raman measurements in multiwavelength aerosol lidar for evaluation of particle backscattering and extinction

    Science.gov (United States)

    Veselovskii, I.; Whiteman, D. N.; Korenskiy, M.; Suvorina, A.; Pérez-Ramírez, D.

    2015-10-01

    Vibrational Raman scattering from nitrogen is commonly used in aerosol lidars for evaluation of particle backscattering (β) and extinction (α) coefficients. However, at mid-visible wavelengths, particularly in the daytime, previous measurements have possessed low signal-to-noise ratio. Also, vibrational scattering is characterized by a significant frequency shift of the Raman component, so for the calculation of α and β information about the extinction Ångström exponent is needed. Simulation results presented in this study demonstrate that ambiguity in the choice of Ångström exponent can be the a significant source of uncertainty in the calculation of backscattering coefficients when optically thick aerosol layers are considered. Both of these issues are addressed by the use of pure-rotational Raman (RR) scattering, which is characterized by a higher cross section compared to nitrogen vibrational scattering, and by a much smaller frequency shift, which essentially removes the sensitivity to changes in the Ångström exponent. We describe a practical implementation of rotational Raman measurements in an existing Mie-Raman lidar to obtain aerosol extinction and backscattering at 532 nm. A 2.3 nm width interference filter was used to select a spectral range characterized by low temperature sensitivity within the anti-Stokes branch of the RR spectrum. Simulations demonstrate that the temperature dependence of the scattering cross section does not exceed 1.5 % in the 230-300 K range, making correction for this dependence quite easy. With this upgrade, the NASA GSFC multiwavelength Raman lidar has demonstrated useful α532 measurements and was used for regular observations. Examples of lidar measurements and inversion of optical data to the particle microphysics are given.

  4. Polarized Raman spectroscopy unravels the biomolecular structural changes in cervical cancer

    Science.gov (United States)

    Daniel, Amuthachelvi; Prakasarao, Aruna; Dornadula, Koteeswaran; Ganesan, Singaravelu

    2016-01-01

    Polarized Raman spectroscopy has emerged as a promising technique giving a wealth of information about the orientation and symmetry of bond vibrations in addition to the general chemical information from the conventional Raman spectroscopy. In this regard, polarized Raman Spectroscopic technique was employed to study the changes in the orientation of biomolecules in normal and cancerous conditions. This technique was compared to the conventional Raman spectroscopic technique and was found to yield additional information about the orientation of tyrosine, collagen and DNA. The statistically analyzed depolarization ratios by Linear Discriminant Analysis yielded better accuracy than the statistical results of conventional Raman spectroscopy. Thus, this study reveals that polarized Raman spectroscopy has better diagnostic potential than the conventional Raman spectroscopic technique.

  5. Raman Imaging

    Science.gov (United States)

    Stewart, Shona; Priore, Ryan J.; Nelson, Matthew P.; Treado, Patrick J.

    2012-07-01

    The past decade has seen an enormous increase in the number and breadth of imaging techniques developed for analysis in many industries, including pharmaceuticals, food, and especially biomedicine. Rather than accept single-dimensional forms of information, users now demand multidimensional assessment of samples. High specificity and the need for little or no sample preparation make Raman imaging a highly attractive analytical technique and provide motivation for continuing advances in its supporting technology and utilization. This review discusses the current tools employed in Raman imaging, the recent advances, and the major applications in this ever-growing analytical field.

  6. Crystallization and spectroscopic studies of manganese malonate

    Indian Academy of Sciences (India)

    Varghese Mathew; Jochan Joseph; Sabu Jacob; K E Abraham

    2010-08-01

    The preparation of manganese malonate crystals by gel method and its spectroscopic studies are reported. X-ray diffraction (XRD) pattern reveals the crystalline nature. The FTIR and FT Raman spectra of the crystals are recorded and the vibrational assignments are given with possible explanations. Diffuse reflectance spectroscopy (DRS) is used to measure the bandgap (g) of the material.

  7. Raman spectroscopy of bone metastasis

    Science.gov (United States)

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

    2012-02-01

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

  8. A Raman laser system for multi-wavelength satellite laser ranging

    Institute of Scientific and Technical Information of China (English)

    HU Jingfu; YANG Fumin; ZHANG Zhongping; K. Hamal; I. Prochazka; J. Blazej

    2004-01-01

    In order to develop a laser system for multi-wavelength satellite laser ranging,the joint group of the Shanghai Astronomical Observatory and the Czech Technical University has studied the conversion efficiency of the Raman-shifting beam and its spatial characteristics. We adopted a 0.53 μm laser with pulse width of 35 ps and peak energy of 35 mJ, the second harmonic of a Nd:YAG actively and passively mode-locked laser, to pump a one-meter-long Raman tube which is full of H2with high pressure at the Prague-based laboratory. We get the first Stokes laser (0.68 μm): 7 mJ (single pulse) with beam divergence of 40" (arcsecond) and spatial wobbling of less than 4"; and the first anti-Stokes laser (0.43 μm): 2 mJ (single pulse) with divergence of 56" and spatial wobbling of less than 4". The emitting beam from the Raman cell also includes 0.53 μm:10 mJ (single pulse) with divergence of 40" and spatial wobbling of less than 7".According to the radar link equation and based on the above obtained multi-wavelength's energy, we can estimate the detection probabilities for three colors respectively. It is shown by the result that the developed multi-wavelength Raman laser system has the capability of satellite ranging. The Raman laser system will be installed at the laser station in Shanghai Astronomical Observatory to research the multi-wavelength satellite laser ranging.

  9. 二元碱金属硅酸盐玻璃团簇结构的拉曼散射活性及其阳离子效应%Raman Spectroscopic Quantitative Analysis of Cluster Structure of Binary Alkali Silicate Glasses

    Institute of Scientific and Technical Information of China (English)

    王志超; 尤静林; 王媛媛; 牛玉静; 戴苏娟

    2011-01-01

    提出一种拉曼光谱校正方法.通过计算二元碱会属硅酸盐团簇基元的拉曼光谱,对实验光谱高频区的非桥氧(Onb)对称伸缩振动的强度进行了校正,从而建立谱峰强度和团簇实际浓度的直观相关关系,同时,分析研究了二元碱金属硅酸盐玻璃阳离子对谱峰强度的影响.校正后的拉曼光谱可以真实地显示同化学成分的二元碱金属硅酸盐玻璃表观实验拉曼谱峰强度随着阳离子的不同而变化.在环境和实验条件一致的情况下,这种强度的差异显然是由阳离子的不同所引起的.%A calibration method for Raman spectroscopic quantitative analysis of binary alkaline silicate glasses is proposed. By applying ab initio quantum chemistry simulation, Raman optical activities (ROA) of various cluster units consisting of siliconoxygen tetrahedra (SiOT) with different number of non-bridging oxygen (NBO) can be obtained, Thus, experimental results could be calibrated in order to reflect and represent directly the true relative density of various silicon-oxygen tetrahedra existing inside the silicate glasses. Cation effect on the intensity of Raman bands was also observed and discussed.

  10. Micro-Raman Spectroscopy for the Determination of Local Temperature Increases in TiO2 Thin Films due to the Effect of Radiation.

    Science.gov (United States)

    Gallardo, Juan Jesús; Navas, Javier; Zorrilla, David; Alcántara, Rodrigo; Valor, Diego; Fernández-Lorenzo, Concha; Martín-Calleja, Joaquín

    2016-07-01

    This study applied a classic method involving Raman spectroscopy and the use of Stokes and anti-Stokes peaks to measure the temperature of TiO2 thin films found in dye-sensitized solar cells (DSSCs). In addition, three mathematical formulae were used and analyzed to estimate the increase in temperature generated solely by the effect of the radiation. The tests and calculations performed showed an increase in the temperature of the TiO2 film. That is, the films were heated by the radiation they were exposed to. A temperature increase of up to 30 K was detected for the sample with a single layer of TiO2, and over 40 K for the sample with three layers for the highest radiation powers used, and greater increases in temperature were observed in the thicker films.

  11. Towards Single-Shot Detection of Bacterial Endospores via Coherent Raman Spectroscopy

    Science.gov (United States)

    Pestov, Dmitry; Wang, Xi; Ariunbold, Gombojav; Murawski, Robert; Sautenkov, Vladimir; Sokolov, Alexei; Scully, Marlan

    2007-10-01

    Recent advances in coherent anti-Stokes Raman scattering (CARS) spectroscopy hold exciting promise to make the most out of now readily available ultrafast laser sources. Techniques have been devised to mitigate the nonresonant four-wave-mixing in favor of informative Raman-resonant signal. In particular, a hybrid technique for CARS (see Science 316, 265 (2007)) brings together the advantages of coherent broadband pump-Stokes excitation of molecular vibrations and their time-delayed but frequency-resolved probing via a spectrally narrowed and shaped laser pulse. We apply this technique to the problem of real-time detection of warfare bioagents and report single-shot acquisition of a distinct CARS spectrum from a small volume of B. subtilis endospores (˜10^4 spores), a harmless surrogate for B. anthracis. We study the dependence of the CARS signal on the energy of the ultrashort preparation pulses and find the limit on the pulse energy fluence (˜0.2 J/cm^2), imposed by the laser-induced damage of the spores.

  12. Resolved-sideband Raman cooling of an optical phonon in semiconductor materials

    Science.gov (United States)

    Zhang, Jun; Zhang, Qing; Wang, Xingzhi; Kwek, Leong Chuan; Xiong, Qihua

    2016-09-01

    The radiation pressure of light has been widely used to cool trapped atoms or the mechanical vibrational modes of optomechanical systems. Recently, by using the electrostrictive forces of light, spontaneous Brillouin cooling and stimulated Brillouin excitation of acoustic modes of the whispering-gallery-type resonator have been demonstrated. The laser cooling of specific lattice vibrations in solids (that is, phonons) proposed by Dykman in the late 1970s, however, still remains sparsely investigated. Here, we demonstrate the first strong spontaneous Raman cooling and heating of a longitudinal optical phonon (LOP) with a 6.23 THz frequency in polar semiconductor zinc telluride nanobelts. We use the exciton to resonate and assist photoelastic Raman scattering from the LOPs caused by a strong exciton–LOP coupling. By detuning the laser pump to a lower (higher) energy-resolved sideband to make a spontaneous scattering photon resonate with an exciton at an anti-Stokes (Stokes) frequency, the dipole oscillation of the LOPs is photoelastically attenuated (enhanced) to a colder (hotter) state.

  13. Vibrational spectroscopic characterization of fluoroquinolones

    Science.gov (United States)

    Neugebauer, U.; Szeghalmi, A.; Schmitt, M.; Kiefer, W.; Popp, J.; Holzgrabe, U.

    2005-05-01

    Quinolones are important gyrase inhibitors. Even though they are used as active agents in many antibiotics, the detailed mechanism of action on a molecular level is so far not known. It is of greatest interest to shed light on this drug-target interaction to provide useful information in the fight against growing resistances and obtain new insights for the development of new powerful drugs. To reach this goal, on a first step it is essential to understand the structural characteristics of the drugs and the effects that are caused by the environment in detail. In this work we report on Raman spectroscopical investigations of a variety of gyrase inhibitors (nalidixic acid, oxolinic acid, cinoxacin, flumequine, norfloxacin, ciprofloxacin, lomefloxacin, ofloxacin, enoxacin, sarafloxacin and moxifloxacin) by means of micro-Raman spectroscopy excited with various excitation wavelengths, both in the off-resonance region (532, 633, 830 and 1064 nm) and in the resonance region (resonance Raman spectroscopy at 244, 257 and 275 nm). Furthermore DFT calculations were performed to assign the vibrational modes, as well as for an identification of intramolecular hydrogen bonding motifs. The effect of small changes in the drug environment was studied by adding successively small amounts of water until physiological low concentrations of the drugs in aqueous solution were obtained. At these low concentrations resonance Raman spectroscopy proved to be a useful and sensitive technique. Supplementary information was obtained from IR and UV/vis spectroscopy.

  14. Characterization of the corrosion products using Moessbauer and Raman Spectroscopy

    International Nuclear Information System (INIS)

    A presentation will be given of some of the currently used spectroscopic techniques for analyzing corroded steel structures. Moessbauer spectroscopic and Micro-Raman spectroscopic are two important analytical techniques for investigating the corrosion coatings which form on steels exposed in a diverse range of environments. Both methods are non-destructive and can be applied in-situ to study the corrosion in the laboratory or in the field where the structures themselves are located. The moessbauer and Raman spectroscopic techniques are complementary in providing details of the corrosion products within different spatial resolutions. Moessbauer and Raman spectroscopic is the only techniques which can uniquely identify all the iron oxides and measure the fraction of each in corrosion coatings. It can be used in scattering geometry to study the corrosion products as the remain attached to the substrate, or it can be used in transmission geometry to analyze coatings which have been removed or have flaked from the steel. Generally several square centimeters of coating are analyzed by Moessbauer spectroscopy which is regarded as a bulk analytical technique. Micro-Raman spectroscopy, on the other hand, allows identification of the corrosion products in the coating to about 2 micron spatial resolution. Although presently unable to measure the fraction of each oxide, Micro-Raman spectroscopy is able to identify the oxides to be mapped in three dimensions, across the surface of the coating, as well as through the coating thickness using metallographic cross-section analysis. (Author)

  15. Identification of minerals and meteoritic materials via Raman techniques after capture in hypervelocity impacts on aerogel

    Energy Technology Data Exchange (ETDEWEB)

    Burchell, M J; Mann, J; Creighton, J A; Kearsley, A; Graham, G A; Esposito, A P; Franchi, I A; Westphal, A J; Snead, C

    2004-10-04

    For this study, an extensive suite of mineral particles analogous to components of cosmic dust were tested to determine if their Raman signatures can be recognized after hypervelocity capture in aerogel. The mineral particles were mainly of greater than 20 micrometers in size and were accelerated onto the silica aerogel by light gas gun shots. It was found that all the individual minerals captured in aerogel could be subsequently identified using Raman (or fluorescent) spectra. The beam spot size used for the laser illumination was of the order of 5 micrometers, and in some cases the captured particles were of a similar small size. In some samples fired into aerogel there was observed a shift in the wavenumbers of some of the Raman bands, a result of the trapped particles being at quite high temperatures due to heating by the laser. Temperatures of samples under laser illumination were estimated from the relative intensities of Stokes and anti-Stokes Raman bands, or, in the case of ruby particles, from the wavenumber of fluorescence bands excited by the laser. It was found that the temperature of particles in aerogel varied greatly, dependent upon laser power and the nature of the particle. In the worst case, some particles were shown to have temperatures in the 500-700 C range at a laser power of about 3 mW at the sample. However most of the mineral particles examined at this laser power had temperatures below 200 C. This is sufficiently low a temperature not to damage most materials expected to be found captured in aerogel in space. In addition, selected meteorite samples were examined to obtain Raman signatures of their constituent minerals and were then shot into aerogel. It was possible to find several Raman signatures after capture in aerogel and obtain a Raman map of a whole grain in situ in the aerogel. Finally, a Raman analysis was carried out of a particle captured in aerogel in space and carbonaceous material identified. In general therefore it is

  16. Surface-Enhanced Raman Scattering and Biophysics

    Science.gov (United States)

    Kneipp, Katrin

    2001-03-01

    Surface-enhanced Raman scattering (SERS) is a phenomenon resulting in strongly increased Raman signals from molecules which have been attached to metallic nanostructures such as colloidal silver or gold particles. The effect combines the structural information content of a vibrational spectroscopy with extremely high sensitivity and in some cases, it showes promise in overcoming the low-sensitivity problems inherent in Raman spectroscopy. Cross sections effective in SERS can reach 10 16 to 10 15 cm2 per molecule corresponding to enhancement factors of about fourteen orders of magnitude compared with “normal” non-resonant Raman scattering. Such extremely large cross sections are sufficient for single molecule Raman spectroscopy. The high sensitivity and particularly the single molecule capabilities open up exciting perspectives for SERS as tool for basic research in biophysics, biochemistry and in laboratory medicine, where it allows to study extremely small amounts of biolomedically relevant molecules in order to understand development of diseases, treatment and therapy control based on molecular structural information at the single molecule level. The most spectacular applications might appear in rapidly spectroscopic characterization of specific DNA fragments down to structurally sensitive detection of single bases in order to elucidate the human genome sequence without any labeling technology. I will briefly introduce the SERS effect and report experiments with Raman scattering of single molecules. Potential and limitations of surface-enhanced Raman techniques as a tool in biophysics and biomedical spectroscopy will be considered.

  17. 唇腺炎性病变组织的共聚焦显微拉曼光谱特征研究%Research on the Confocal Raman micro­spectroscopic Characters of Inflammatory Labial Gland Tissues

    Institute of Scientific and Technical Information of China (English)

    薛丽丽; 骆献阳; 蔡巧玲; 孙佩; 陈培琼; 闫冰

    2015-01-01

    目的:研究唇腺炎性病变组织的拉曼光谱指纹特征,为拉曼光谱技术临床鉴别诊断唇腺炎性病变提供理论基础。方法:收集舍格伦综合征病变唇腺30例、唇腺急性炎症组织18例及正常唇腺组织30例,应用激光共聚焦显微拉曼光谱仪对唇腺组织进行拉曼光谱检测。应用主成分分析法(Principal component analysis,PCA)及判别函数(Discrimination function analysis,DFA)对光谱数据进行分析,研究唇腺组织光谱指纹诊断价值。结果:唇腺炎症组织与正常组织光谱间存在光谱指纹差异,这些差异代表了某些蛋白、核酸及脂类物质等生物大分子发生改变。PCA-DFA 分析发现这些差异性拉曼光谱具有鉴别诊断价值,可以区分不同唇腺组织,总体诊断准确率达91.8%,经交互验证后准确率为89.4%。结论:不同唇腺炎症组织及正常组织间拉曼光谱存在差异,不仅揭示生物大分子改变,还具有临床鉴别诊断价值。拉曼光谱技术在唇腺炎性病变组织鉴别诊断具有巨大应用潜力。%Objective:Research the Raman spectra of inflammatory labial gland tissues in order to provide a research-based theoretical foundation for applying Raman spectroscopy to diagnoses the inflammatory labial gland diseases.Meth­ods:30 samples of Sjogren’s syndrome labial glands,18 samples of acute inflammatory labial glands and 30 samples of normal labial glands were collected and scanned by confocal Raman micro-spectrometer.The methods of principal com-ponent analysis (PCA)and discrimination function analysis (DFA)were employed to analyze the spectral data and dis-criminate the different tissues.Results:Differences were discovered between in the Raman spectra of various labial gland tissues,which were assigned to biomolecules such as proteins,nucleic acids and lipids.The accuracy of discrimination carried out by PCA-DFA reached 91.8% and the accuracy of cross

  18. Raman Scattering by Molecular Hydrogen and Nitrogen in Exoplanetary Atmospheres

    CERN Document Server

    Oklopčić, Antonija; Heng, Kevin

    2016-01-01

    An important source of opacity in the atmospheres of exoplanets at short visible and near-UV wavelengths is Rayleigh scattering of light on molecules. It is accompanied by a related, albeit weaker process -- Raman scattering. In this paper, we analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide valuable information about planetary atmospheres. Raman scattering affects the geometric albedo spectra of planets in two main ways. Firstly, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Secondly, it shifts the wavelengths of spectral features in the reflected light causing the so-called Raman ghost lines. Observing the Raman peaks in the albedo could be used to measure the column density of the scattering molecule, thus providing constrains on the presence of clouds and hazes in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically iden...

  19. RAMAN SPECTROSCOPY STRUCTURAL STUDY OF FIRED CONCRETE

    Directory of Open Access Journals (Sweden)

    ŠÁRKA PEŠKOVÁ

    2011-12-01

    Full Text Available Raman spectroscopic structural analysis of concrete cementious matrix represents elegant method to determination of thermal history of highly exposed concrete. Experiments were carried out in furnace at 1200°C. On the surface of heated concrete mechanical cracks and the mixture of dicalcium silicate and gehlenite were found, while inside the cracks the development of gehlenite, pseudowollastonite, pseudobrookite and various iron oxides and spinels was observed. The products of chemical reactions analyzed by Raman spectroscopy can be used as markers for the identification and understanding the structural changes during a fire treatment.

  20. In situ Raman spectroscopic analysis of the coking resistance mechanism on SrZr0.95Y0.05O3-x surface for solid oxide fuel cell anodes

    Science.gov (United States)

    Nagasawa, Tsuyoshi; Chen, Dongchang; Lai, Samson Yuxiu; Liu, Meilin; Hanamura, Katsunori

    2016-08-01

    While the coking resistance of Ni/yttria-stabilized zirconia (YSZ) anodes in solid oxide fuel cells (SOFCs) toward hydrocarbon fuel can be improved by adding SrZr0.95Y0.05O3-x (SZY) as a proton conductor, the exact mechanism is still unclear. In this study, the surface chemistry of SZY is investigated using in situ Raman spectroscopy to clarify the coking resistance mechanism. Upon exposure to dry propane at 500 °C, the intensity of the Raman peaks corresponding to sbnd CO3 species decreases with time, suggesting that the surface-located sbnd CO3 groups are consumed through a reaction with deposited carbon or dry reforming of propane, which reduces the tendency of coking. These consumed sbnd CO3 groups can then be regenerated through a reaction between water vapor and deposited carbon. The presence of adsorbed water on SZY, which facilitates a carbon removal reaction and the steam reforming of propane, is confirmed by thermogravimetric analysis (TGA). The reactivity of the sbnd CO3 groups and the adsorbed water on SZY thus contribute to removing deposited carbon, resulting in the improved coking resistance of Ni/YSZ-SZY anode.

  1. Molecular structure, spectroscopic (FT-IR, FT-Raman, NMR, UV) studies and first-order molecular hyperpolarizabilities of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine by density functional method

    Science.gov (United States)

    Subramanian, N.; Sundaraganesan, N.; Jayabharathi, J.

    2010-07-01

    Quantum chemical calculations of energies, geometrical structure and vibrational wavenumbers of 1,2-bis(3-methoxy-4-hydroxybenzylidene)hydrazine [vanillin azine (VA)] were carried out by using density functional (DFT/B3LYP) method with 6-31G(d) as basis set. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from solid phase FT-IR and FT-Raman spectra are assigned based on the results of the theoretical calculations. The observed spectra are found to be in good agreement with calculated values. The electric dipole moment ( μ) and the first hyperpolarizability ( β) values of the investigated molecule have been computed using ab initio quantum mechanical calculations. The calculation results also show that the VA molecule might have microscopic nonlinear optical (NLO) behavior with non-zero values. A detailed interpretation of the infrared and Raman spectra of VA was also reported. The energy and oscillator strength calculated by time-dependent density functional theory (TD-DFT) results complements with the experimental findings. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. The theoretical NMR chemical shifts complement with experimentally measured ones.

  2. Quantum mechanical study of the structure and spectroscopic (FT-IR, FT-Raman, 13C, 1H and UV), NBO and HOMO-LUMO analysis of 2-quinoxaline carboxylic acid

    Science.gov (United States)

    Prabavathi, N.; Nilufer, A.; Krishnakumar, V.

    The FTIR and FT-Raman spectra of 2-quinoxaline carboxylic acid (2-QCA) has been recorded in the region 4000-450 and 4000-100 cm-1, respectively. The conformational analysis, optimized geometry, frequency and intensity of the vibrational bands of 2-QCA were obtained by the density functional theory (DFT) with complete relaxation in the potential energy surface using 6-31G(d) basis set. The harmonic vibrational frequencies were calculated and the scaled values have been compared with experimental FTIR and FT-Raman spectra. The observed and the calculated frequencies are found to be in good agreement. The 1H and13C NMR spectra have been recorded and 1H and 13C nuclear magnetic resonance chemical shifts of the molecule were also calculated using the gauge independent atomic orbital (GIAO) method and their respective linear correlations were obtained. The theoretical UV-visible spectrum of the compound using CIS method and the electronic properties, such as HOMO and LUMO energies, were performed by time-dependent DFT (TD-DFT) approach. The calculated HOMO and LUMO energies show that charge transfer occurs within molecule. The Mulliken charges, the values of electric dipole moment (μ) of the molecule were computed using DFT calculations. The change in electron density (ED) in the σ* antibonding orbitals and stabilization energies E(2) have been calculated by natural bond (NBO) analysis to give clear evidence of stabilization originating in the hyper conjugation of hydrogen-bonded interactions.

  3. X-ray diffraction and Raman spectroscopic investigations on CaZrTi2O7sbnd Y2Ti2O7 system: Delineation of phase fields consisting of potential ceramic host materials

    Science.gov (United States)

    Jafar, M.; Achary, S. N.; Salke, Niliesh P.; Sahu, A. K.; Rao, Rekha; Tyagi, A. K.

    2016-07-01

    Phase evolution from CaZrTi2O7 (zirconolite) to Y2Ti2O7 (pyrochlore) have been delineated by systematic characterization of a series of sample with composition as Ca1-xZr1-xY2xTi2O7 (0.00 ≤ x ≤ 1.00) by powder XRD, Raman spectroscopy, SEM and EDS analyses. Comparative analyses of XRD and Raman spectra revealed sequential evolution of phases with increasing concentration of Y3+ in the compositions. From the XRD studies, three distinct phase fields, namely two layer (2M) and four layer (4M) zirconolite-types and cubic pyrochlore-type are observed in between zirconolite (CaZrTi2O7) and Y2Ti2O7. 4M-zirconolite phase is observed in a narrow range of composition, viz. 0.35 ≤ x ≤ 0.40 while cubic pyrochlore type phase is observed in the compositions with x ≥ 1.20. The unit cell volume of different phases shows a non-linear increasing trend with Y3+ ion concentration which has been attributed to the distribution of cations in different structure and change in their coordination number.

  4. Vibrational assignments, spectroscopic investigation (FT-IR and FT-Raman), NBO, MEP, HOMO‒LUMO analysis and intermolecular hydrogen bonding interactions of 7-fluoroisatin, 7-bromoisatin and 1-methylisatin ‒ A comparative study

    Science.gov (United States)

    Polat, Turgay; Bulut, Fatih; Arıcan, Ilknur; Kandemirli, Fatma; Yildirim, Gürcan

    2015-12-01

    In this comprehensive study, theoretical and experimental studies were carried out on 7-fluoroisatin, 7-bromoisatin and 1-methylisatin using FT-Raman and FT-IR spectra. The optimized geometrical parameters and theoretical vibrational frequencies were calculated by means of density functional theory (DFT/B3LYP) with 6-311++G(d,p) basis set based on scaled quantum mechanical (SQM) method for the first time. The relative abundances of the possible tautomers or conformers found were calculated with respect to the Boltzmann distribution. Moreover, the harmonic vibrational frequencies including IR and Raman intensities, thermodynamic and electronic parameters were computed in detail. The effects of substituents -F, ‒Br and -CH3 on the crucial characteristics pertaining to the title compound of isatin were investigated, and the obtained data were compared with each other. Natural bond orbital (NBO) analysis was applied to study the stability arising from charge delocalization along with the compound. The chemical reactivity parameters (chemical hardness and softness, electronegativity, chemical potential and electrophilicity index) were discussed clearly. The HOMO and LUMO energies determined showed that the serious charge transfer occurs in the title molecules studied. Furthermore, the size, shape, charge density distributions and chemical reactivity sites belonging to the molecules were obtained by mapping electron density isosurface with electrostatic potential surfaces (ESP). Additionally, the hydrogen-bonded complexes were simulated to describe the roles of intermolecular hydrogen bonding on the molecular structures and vibrational frequencies.

  5. Comprehensive quantum chemical and spectroscopic (FTIR, FT-Raman, 1H, 13C NMR) investigations of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane

    Science.gov (United States)

    Arjunan, V.; Anitha, R.; Devi, L.; Mohan, S.; Yang, Haifeng

    2015-01-01

    Aromatic epoxides are causative factors for mutagenic and carcinogenic activity of polycyclic arenes. The 1,2- or 2,3-epoxy compounds are widely used to a considerable extent in the textile, plastics, pharmaceutical, cosmetics, detergent and photochemical industries. The FTIR and FT-Raman spectra of (1,2-epoxyethyl)benzene and (1,2-epoxy-2-phenyl)propane are recorded in the regions 4000-400 cm-1 and 4000-100 cm-1, respectively. The observed fundamentals are assigned to different normal modes of vibration. The structure of the compound has been optimised with B3LYP method using 6-311++G** and cc-pVTZ basis sets. The IR and Raman intensities are determined. The total electron density and molecular electrostatic potential surfaces of the molecule are constructed by using B3LYP/6-311++G(d,p) method to display electrostatic potential (electron + nuclei) distribution. The electronic properties HOMO and LUMO energies were measured. Natural bond orbital analysis of the compounds has been performed to indicate the presence of intramolecular charge transfer. The 1H and 13C NMR chemical shifts of the molecules have been analysed.

  6. Spectroscopic (FT-IR, FT-Raman, NMR and UV-Visible) and quantum chemical studies of molecular geometry, Frontier molecular orbital, NLO, NBO and thermodynamic properties of salicylic acid

    Science.gov (United States)

    Suresh, S.; Gunasekaran, S.; Srinivasan, S.

    2014-11-01

    The solid phase FT-IR and FT-Raman spectra of 2-hydroxybenzoic acid (salicylic acid) have been recorded in the region 4000-400 and 4000-100 cm-1 respectively. The optimized molecular geometry and fundamental vibrational frequencies are interpreted with the aid of structure optimizations and normal coordinate force field calculations based on density functional theory (DFT) method and a comparative study between Hartree Fork (HF) method at 6-311++G(d,p) level basis set. The calculated harmonic vibrational frequencies are scaled and they are compared with experimentally obtained FT-IR and FT-Raman spectra. A detailed interpretation of the vibrational spectra of this compound has been made on the basis of the calculated potential energy distribution (PED). The time dependent DFT method is employed to predict its absorption energy and oscillator strength. The linear polarizability (α) and the first order hyper polarizability (β) values of the investigated molecule have been computed. The electronic properties, such as HOMO and LUMO energies, molecular electrostatic potential (MEP) are also performed. Stability of the molecule arising from hyper conjugative interaction, charge delocalization has been analyzed using natural bond orbital (NBO) analysis.

  7. Spectroscopic data

    CERN Document Server

    Melzer, J

    1976-01-01

    During the preparation of this compilation, many people contributed; the compilers wish to thank all of them. In particular they appreciate the efforts of V. Gilbertson, the manuscript typist, and those of K. C. Bregand, J. A. Kiley, and W. H. McPherson, who gave editorial assistance. They would like to thank Dr. J. R. Schwartz for his cooperation and encouragement. In addition, they extend their grati­ tude to Dr. L. Wilson of the Air Force Weapons Laboratory, who gave the initial impetus to this project. v Contents I. I ntroduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 . . . . . . . . . . . . . . . . 11. Organization ofthe Spectroscopic Table. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Methods of Production and Experimental Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Band Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2...

  8. Surface-enhanced Raman scattering: a new optical probe in molecular biophysics and biomedicine

    DEFF Research Database (Denmark)

    Kneipp, J.; Wittig, B.; Bohr, Henrik;

    2010-01-01

    Sensitive and detailed molecular structural information plays an increasing role in molecular biophysics and molecular medicine. Therefore, vibrational spectroscopic techniques, such as Raman scattering, which provide high structural information content are of growing interest in biophysical and ...

  9. MicroRaman Spectroscopy and Raman Imaging of Basal Cell Carcinoma

    Science.gov (United States)

    Short, M. A.; Zeng, H.; Lui, H.

    2005-03-01

    We have measured the Raman spectra of normal and cancerous skin tissues using a confocal microRaman spectrograph with a sub-micron spatial resolution. We found that the Raman spectrum of a cell nucleolus is different from the spectra measured outside the nucleolus and considerably different from those measured outside the nucleus. In addition, we found significant spectroscopic differences between normal and cancer-bearing sites in the dermis region. In order to utilize these differences for non-invasive skin cancer diagnosis, we have developed a Raman imaging system that clearly demonstrates the structure, location and distribution of cells in unstained skin biopsy samples. Our method is expected to be useful for the detection and characterization of skin cancer based on the known distinct cellular differences between normal and malignant skin.

  10. 不同初始pH值的乙醇发酵过程拉曼光谱分析%Raman Spectroscopic Analysis of Ethanol Fermentation at Various Initial pH Levels

    Institute of Scientific and Technical Information of China (English)

    覃赵军; 赖钧灼; 刘斌; 刘军贤; 王桂文

    2013-01-01

    pH值是影响酵母乙醇发酵的重要因素.应用拉曼光谱初步分析不同初始pH值对乙醇发酵过程的影响.结果显示:1)在3.0、4.5、6.5三个不同初始pH值的培养基中,pH4.5下乙醇产量最高,pH 3.0下最低.2)在发酵的前15h,不同初始pH值下的酵母细胞生物大分子的拉曼信号变化波动大;后期,pH3.0下胞内脂类和蛋白质的拉曼信号最强,pH 6.5最弱;显示在低pH值环境下部分底物可能被转化为胞内储藏物质.3)主成分分析显示,pH值对酵母细胞生理状态的影响从发酵的初始阶段就开始;1440 cm-1和1600 cm-1峰一直是影响主成分PC1、PC2、PC3分值的主要特征峰;说明pH环境可能影响了酵母细胞的脂类物质合成和细胞的呼吸代谢,进而影响了底物的代谢方向和产物的合成.结果表明,拉曼光谱和单细胞分析可以用于剖析微生物发酵过程的生理机制,为乙醇发酵提供全新的参考信息.%The pH level is a prominent factor affects the ethanol fermentation. Optical tweezers Raman spectroscopy is used to analyze the process of ethanol fermentation at the initial pH levels of 3.0, 4.5, 6.5. Major results from this work are as follows: 1) The pH 4. 5 level get the highest ethanol production and the pH 3.0 get the lowest one. 2) Raman intensities of bio-macromolecules of yeast cells at all pH levels exhibite dramatic changes in the first 15 hours. However, at the later stage of the fermentation, the pH 3. 0 level displayes strong Raman intensities of intracellular lipids and proteins while pH 6. 5 level shows weak. This indicates that a portion of substrate may be transformed into intracellular storage material by yeast cells at lower pH level. 3) Principal component analysis reveals that fermentation pH influences the physiological status of yeast cells from the beginning of fermentation, and bands 1440 cm-1 and 1600 cm-1 are the prominent contributors to the component loadings in different

  11. Raman Spectroscopic Study of Tungsten(VI) Oxosulfato Complexes in WO3–K2S2O7–K2SO4 Molten Mixtures: Stoichiometry, Vibrational Properties and Molecular Structure

    DEFF Research Database (Denmark)

    Paulson, Andreas L.; Kalampounias, Angelos G.; Berg, Rolf W.;

    2011-01-01

    for the W oxosulfato complex in the ternary system, generated from inversion symmetry of aWO2(SO4)3 4- moiety resulting in two bridging sulfates. The most characteristic Raman bands for the WVI oxosulfato complexes pertain to W(dO)2 stretching modes (i) at 972 (polarized) and 937 (depolarized) cm-1...... oxosulfato complexes, and the spectral features are adequate for inferring the structural and vibrational properties of the complexes formed. The band characteristics observed in the WdO stretching region (band wavenumbers, intensities, and polarization characteristics) are consistent with a dioxoW(dO)2...... for the vs and vas W(dO)2 modes of WO2(SO4)2 2-, and (ii) at 933 (polarized) and 909 (depolarized) cm-1 for the respective modes of [{WO2(SO4)2}2(μ-SO4)2]8-....

  12. Thiol-thione tautomeric analysis, spectroscopic (FT-IR, Laser-Raman, NMR and UV-vis) properties and DFT computations of 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule

    Science.gov (United States)

    Gökce, Halil; Öztürk, Nuri; Ceylan, Ümit; Alpaslan, Yelda Bingöl; Alpaslan, Gökhan

    2016-06-01

    In this study, the 5-(3-pyridyl)-4H-1,2,4-triazole-3-thiol molecule (C7H6N4S) molecule has been characterized by using FT-IR, Laser-Raman, NMR and UV-vis spectroscopies. Quantum chemical calculations have been performed to investigate the molecular structure (thione-thiol tautomerism), vibrational wavenumbers, electronic transition absorption wavelengths in DMSO solvent and vacuum, proton and carbon-13 NMR chemical shifts and HOMOs-LUMOs energies at DFT/B3LYP/6-311 ++G(d,p) level for all five tautomers of the title molecule. The obtained results show that the calculated vibrational wavenumbers, NMR chemical shifts and UV-vis wavelengths are in a good agreement with experimental data.

  13. Raman Spectroscopic Profile of Ethanol Fermentation in High Gravity Cassava Starch Brewing%浓醪乙醇发酵的单细胞拉曼光谱表征

    Institute of Scientific and Technical Information of China (English)

    李自达; 赖钧灼; 廖威; 刘军贤; 王桂文

    2012-01-01

    应用激光镊子拉曼光谱技术收集500 L发酵罐中木薯淀粉浓醪乙醇发酵过程底物、产物及酵母单细胞的拉曼光谱,以期从单细胞水平为乙醇发酵提供新的认识.结果显示:1)拉曼光谱可以实时监测浓醪乙醇发酵过程底物与产物的变化;2)酵母细胞胞内物质的变化存在类似于产物变化的前发酵期、主发酵期和后发酵期3个阶段,但出现的时间要比产物变化晚约4 h;3)为适应浓醪发酵环境,酵母细胞的生理状态和胞内物质在不断地进行调整,随着环境乙醇浓度的升高,酵母细胞在胞内累积蛋白质和脂类物质,蛋白质二级结构逐渐变为以无规则卷曲为主;4)发酵后期,酵母细胞在胞内累积大量的嘌呤类物质,但细胞间含量存在异质性.上述结果表明,单细胞拉曼光谱技术提供了一种研究微生物发酵的新方法,可从新的角度获知乙醇发酵过程酵母细胞内外的变化信息.%Raman spectroscopy is used to characterize the process of ethanol fermentation and look into the Saccharomyces cerevisiae cells at single-cell level. The ethanol fermentation using high-concentration cassava starch as feedstock is processed in a 500 L fermentor and the Raman spectra of substrate, product and individual yeast cell are acquired by using laser tweezers Raman spectroscopy (LTRS). Major results are as follows: 1) Raman spectroscopy can monitor the dynamic changes of substrate and product during the ethanol fermentation; 2) the changes of intracellular components of yeast cells exhibit three stages, I. E., primary fermentation, main fermentation and later fermentation, which are similar to those of products, but there is a delay of about 4 hi 3) yeast cells amend its physiological state and intracellular compounds to adapt to the high osmotic stress at the initial stage and the high ethanol concentration at the later stage of fermentation. Random coiling dominates the secondary structure of

  14. 不同煤阶热解半焦的FT-Raman光谱研究%FT-Raman spectroscopic characterisation of chars from the pyrolysis of coals of varying rank

    Institute of Scientific and Technical Information of China (English)

    Xiao-jiang Li; Chun-zhu Li

    2005-01-01

    A brown coal, a high-volatile bituminous coal and a low-volatile bituminous coal were pyrolysed at a slow heating rate in a thermogravimetric analyser. The char samples were deconvoluted with 10 Gaussian bands representing the typical structures found in highly disordered carbon materials. Both total Raman intensity (peak area) and the Raman band intensity ratios from spectral deconvolution are useful parameters for the description of the structural features of coal chars. While the chars from the brown coal,the high-volatile bituminous coal and the low-volatile bituminous coal differ significantly at lowpyrolysis temperatures (e.g.600℃), the differences diminish with increasing pyrolysis temperature to 800℃ or 900℃. The ion-exchangeable Na in brown coal affects the char-forming reactions taking place during pyrolysis.%在热天平上采用慢速升温制备了褐煤、高挥发分烟煤和低挥发分烟煤的半焦.采用FT-Raman光谱对半焦进行了分析.半焦800cm-1至1800cm-1的Raman光谱可分解为10个谱带,以表征高度无序炭材料中的典型结构.光谱和谱带的强度比都可用来描述半焦的结构特征.在600℃低温热解时,三种煤半焦的结构差异明显.随热解温度升至800℃或900℃,这种差别消失.褐煤中可交换的钠离子影响热解过程中的成焦反应.

  15. Fourier-transform infrared and Raman spectroscopic evidence for the incorporation of cinnamaldehydes into the lignin of transgenic tobacco (Nicotiana tabacum L.) plants with reduced expression of cinnamyl alcohol dehydrogenase

    International Nuclear Information System (INIS)

    Xylem from stems of genetically manipulated tobacco plants which had had cinnamyl alcohol dehydrogenase (CAD; EC 1.1.1.195) activity down-regulated to a greater or lesser degree (clones 37 and 49, respectively) by the insertion of antisense CAD cDNA had similar, or slightly higher, lignin contents than xylem from wild-type plants. Fourier-transform infrared (FT-IR) microspectroscopy indicated that down-regulation of CAD had resulted in the incorporation of moieties with conjugated carbonyl groups into lignin and that the overall extent of cross-linking, particularly of guaiacyl (4-hydroxy-3-methoxyphenyl) rings, in the lignin had altered. The FT-Raman spectra of manipulated xylem exhibited maxima consistent with the presence of elevated levels of aldehydic groups conjugated to a carbon-carbon double bond and a guaiacyl ring. These maxima were particularly intense in the spectra of xylem from clone 37, the xylem of which exhibits a uniform red coloration, and their absolute frequencies matched those of coniferaldehyde. Furthermore, xylem from clone 37 was found to have a higher content of carbonyl groups than that of clone 49 or the wild-type (clone 37: clone 49: wild-type; 2.4:1.6:1.0) as measured by a degradative chemical method. This is the first report of the combined use of FT-IR and FT-Raman spectroscopies to study lignin structure in situ. These analyses provide strong evidence for the incorporation of cinnamaldehyde groups into the lignin of transgenic plants with down-regulated CAD expression. In addition, these non-destructive analyses also suggest that the plants transformed with antisense CAD, in particular clone 37, may contain lignin that is less condensed (cross-linked) than that of the wild-type. (author)

  16. FT-Raman signatures of genomic DNA from plant tissues

    OpenAIRE

    Cristina M. Muntean; Adela HALMAGYI; Puia, Mircea D.; Pavel, Ioana

    2009-01-01

    The vibrational spectra of eight genomic DNAs from leaf tissues (sword fern (Nephrolepis exaltata L.), chrysanthemum (Dendranthema grandiflora Ramat.), redwood (Sequoia sempervirens D. Don. Endl.), orchids (Cymbidium × hybrida), common sundew (Drosera rotundifolia L.), potato (Solanum tuberosum L.) and scopolia (Scopolia carniolica Jacq.)) have been analyzed using FT-Raman spectroscopy, in the wavenumber range 500–1800 cm–1.FT-Raman signatures, spectroscopic assignments and structural interpr...

  17. Catching Conical Intersections in the Act; Monitoring Transient Electronic Coherences by Attosecond Stimulated X-Ray Raman Signals

    Science.gov (United States)

    Bennett, Kochise; Kowalewski, Markus; Dorfman, Konstantin; Mukamel, Shaul

    Conical intersections (CIs) dominate the pathways and outcomes of virtually all photochemical molecular processes. Despite extensive experimental and theoretical effort, CIs have not been directly observed yet and the experimental evidence is inferred from fast reaction rates and vibrational signatures. We show that short X-ray pulses can directly detect the passage through a CI with the adequate temporal and spectral sensitivity. The non-adiabatic coupling that exists in the region of a CI redistributes electronic population but also generates electronic coherence. This coherent oscillation can then be detected via a coherent Raman process that employs a composite femtosecond/attosecond X-ray pulse. This technique, dubbed Transient Redistribution of Ultrafast Electronic Coherences (TRUECARS) is reminiscent of Coherent Anti-Stokes Raman Spectroscopy (CARS) in that a coherent oscillation is set in motion and then monitored, but differs in that the dynamics is electronic (CARS generally observes nuclear dynamics) and the coherence is generated internally by passage through a region of non-adiabatic coupling rather than by an externally applied laser. Support provided by U.S. Department of Energy through Award No. DE-FG02-04ER15571, the National Science Foundation (Grant No CHE-1361516), and the Alexander von Humboldt foundation through the Feodor Lynen program.

  18. Vibrational (FT-IR, FT-Raman) and UV-Visible spectroscopic studies, HOMO-LUMO, NBO, NLO and MEP analysis of Benzyl (imino (1H-pyrazol-1-yl) methyl) carbamate using DFT calculaions

    Science.gov (United States)

    Shankar Rao, Y. B.; Prasad, M. V. S.; Udaya Sri, N.; Veeraiah, V.

    2016-03-01

    This paper contains a combined experimental and theoretical study of vibrational and electronic properties of Benzyl(imino(1H-pyrazol-1-yl)methyl)carbamate (BPMC) molecule. The FT-IR and FT-Raman spectra of the title molecule in solid phase were recorded in the region 4000-400 cm-1 and 4000-50 cm-1, respectively. The UV absorption spectrum of the studied compound dissolved in ethanol was recorded in the range of 180-400 nm. The molecular geometries calculated using density functional theory (DFT) was compared with available experimental data. The vibrational spectra calculated at the B3LYP/6-31G(d,p) level were compared with the experimental spectra and assignment to each vibrational frequency was assigned on the basis of potential energy distribution (PED). The calculated electronic and nonlinear optical properties of the title molecule were reported. Furthermore, the thermodynamic properties of the molecule were discussed.

  19. Spectroscopic (FT-IR and FT-Raman) investigation, first order hyperpolarizability, NBO, HOMO-LUMO and MEP analysis of 6-nitrochromone by ab initio and density functional theory calculations

    Science.gov (United States)

    Senthil kumar, J.; Jeyavijayan, S.; Arivazhagan, M.

    2015-02-01

    The vibrational spectral analysis is carried out using FT-Raman and FT-IR spectroscopy in the range 3500-50 cm-1 and 4000-400 cm-1, respectively, for 6-nitrochromone (6NC). The molecular structure, fundamental vibrational frequencies and intensity of the vibrational bands are interpreted with the aid of structure optimization and normal coordinates force field calculation based on ab initio HF and DFT gradient calculations employing the HF/6-311++G(d,p) and B3LYP/6-311++G(d,p) basis set. Stability of the molecule has been analyzed using NBO analysis. The calculated HOMO and LUMO energies show that charge transfer occurs within the molecule. Thermodynamic properties like entropy, heat capacity, zero-point energy and Mulliken's charge analysis have been calculated for the 6NC. The complete assignments were performed on the basis of total energy distribution (TED) of the vibrational modes with scaled quantum mechanical (SQM) method. The MEP map shows the negative potential sites are on oxygen atoms as well as the positive potential sites are around the hydrogen atoms.

  20. Gauss-Newton based kurtosis blind deconvolution of spectroscopic data

    Institute of Scientific and Technical Information of China (English)

    Jinghe Yuan; Ziqiang Hu

    2006-01-01

    @@ The spectroscopic data recorded by dispersion spectrophotometer are usually degraded by the response function of the instrument. To improve the resolving power, double or triple cascade spectrophotometer and narrow slits have been employed, but the total flux of the radiation decreases accordingly, resulting in a lower signal-to-noise ratio (SNR) and a longer measuring time. However, the spectral resolution can be improved by mathematically removing the effect of the instrument response function. Based on the ShalviWeinstein criterion, a Gauss-Newton based kurtosis blind deconvolution algorithm for spectroscopic data is proposed. Experiments with some real measured Raman spectroscopic data show that this algorithm has excellent deconvolution capability.

  1. In Situ Raman Spectroscopic of Cerium Surface Oxidation and Reduction Processes%金属铈表面氧化还原过程的原位拉曼光谱研究

    Institute of Scientific and Technical Information of China (English)

    吕俊波; 郭淑兰; 李赣

    2013-01-01

    The surface oxidation and reduction processes of cerium were monitored by in situ microscope Raman spectroscopy.A peak at 462 cm-1 attributed to the characteristic vibration of CeO2 disappeared and two sharp peaks at 2132 and 2239 cm-1 attributed to the electronic scattering of Ce3+ were observed at high temperature and vacuum conditions.The results indicated that the surface oxide on cerium sample were transformed from CeO2 to Ce2O3.According to the changes of peak intensities at 1503,1796,2100cm-1,also attributed to electronic scattering of Ce3+and the characteristic vibration peak of CeO2,the surface oxidation process of cerium in the air could be divided into three steps.First,all cerium oxide layers with different cerium valence increased quickly.Then,the outer CeO2 layer stopped growing,but those cerium oxide layers contained Ce3+ continued growing.Finally,CeO2 layer increased quickly again with the appearance of OH-at 3603 cm-1%采用显微拉曼光谱仪原位监测了金属铈表面的氧化和还原过程.2132和2239 cm-1处尖锐Ce3+电子散射峰的出现及462 cm-1处CeO2特征振动峰的消失表明,在高温、高真空条件下金属铈表层的CeO2已转变为Ce2O3.根据1503,1796和2113 cm-1处多个Ce3+电子散射峰及CeO2特征振动峰强度随时间的变化关系,可将金属Ce在空气中的氧化过程分为3个阶段,首先不同价态铈氧物层均快速增长,随后外层的CeO2陷入停顿,含Ce3+的铈氧物层继续增长,最后随着3603 cm-1处OH-的出现,CeO2再次快速增长.

  2. 大别山高压-超高压片麻岩锆石的拉曼光谱学研究%Laser-Raman spectroscopic studies on zircons from the HP-UHP gneisses of Dabie Mountains

    Institute of Scientific and Technical Information of China (English)

    刘文元; 刘景波

    2009-01-01

    The zircons from gneisses in high and ultrahigh-pressure (HP-UHP) metamorphic zones of the Dabie Mountains have been investigated by using Laser Raman microprobe analysis, cathodoluminescence (CL) images, U-Pb ages and trace elements measured by LA-ICP-MS. Most of the FWHMs (full widths at half-maximum) of 1008cm~(-1) band of zircons are less than 20cm~(-1), suggesting that zircons are well crystallized to moderately damaged. The early inherited zircons from gneisses had undergone significant annealing and recrystallization during the HP-UHP metamorphic event. The α-doses that zircons suffered are probably accumulated from about 200Ma, indicating that HP-UHP metamorphic rocks have been exhumed to the surface of the earth at this time. The magmatic events of Cretaceous age in North Dabie may exert little effect on the HP-UHP rocks, which most of FWHMs and frequencies of zircons in Dabie Moutains fall into the natural radiation damage trend (RDT) , indicating completely recrystalization of zircons during the HP-UHP metamorphic event.%对大别山高压-超高压片麻岩的锆石进行了激光拉曼探针、阴极发光(CL)、U-Pb年龄和U、Th等微量元素的测定分析.研究结果表明:锆石拉曼光谱1008cm~(-1)峰的半高宽普遍小于20cm~(-1),指示锆石结晶程度较好到中等程度的蜕晶化;早期继承锆石在三叠纪高压-超高压变质作用中经历了退火和重结晶作用,所受的放射性通量是从200Ma的早侏罗纪开始积累的,表明高压-超高压岩石在这一时间已出露地表;北大别白垩纪岩浆热事件对高压-超高压岩石的影响很小;大多数锆石数据都落在天然锆石的放射性破坏趋势(RDT)中,表明锆石在高压、超高压过程中基本发生了完全的重结晶.

  3. Raman microspectroscopic study of oral buccal mucosa

    Science.gov (United States)

    Behl, Isha; Mamgain, Hitesh; Deshmukh, Atul; Kukreja, Lekha; Hole, Arti R.; Krishna, C. Murali

    2014-03-01

    Oral cancer is the most common cancer among Indian males, with 5-year- survival-rates of less than 50%. Efficacy of Raman spectroscopic methods in non-invasive and objective diagnosis of oral cancers and confounding factors has already been demonstrated. The present Raman microspectroscopic study was undertaken for in-depth and site-specific analysis of normal and tumor tissues. 10 normal and 10 tumors unstained sections from 20 tissues were accrued. Raman data of 160 x 60 μm and 140 x 140 μm in normal and tumor sections, respectively, were acquired using WITec alpha 300R equipped with 532 nm laser, 50X objective and 600 gr/mm grating. Spectral data were corrected for CCDresponse, background. First-derivitized and vector-normalized data were then subjected to K-mean cluster analysis to generate Raman maps and correlated with their respective histopathology. In normal sections, stratification among epithelial layers i.e. basal, intermediate, superficial was observed. Tumor, stromal and inflammatory regions were identified in case of tumor section. Extracted spectra of the pathologically annotated regions were subjected to Principal component analysis. Findings suggest that all three layers of normal epithelium can be differentiated against tumor cells. In epithelium, basal and superficial layers can be separated while intermediate layer show misclassifications. In tumors, discrimination of inflammatory regions from tumor cells and tumor-stroma regions were observed. Finding of the study indicate Raman mapping can lead to molecular level insights of normal and pathological states.

  4. Anti-Stokes-enhanced tunnelling ionization of polar molecules

    International Nuclear Information System (INIS)

    We generalize the correct account for molecule vibrational motion in tunnelling ionization, proposed earlier (Kornev and Zon 2012 Phys. Rev. A 86 043401), to the case of polar molecules. We consider the tunnel effect in both dc and ac fields, taking into account perturbation of vibrational motion by an external field. We develop a method for accounting for dipole moment on the base of the electronic wave function expansion over dipole-spherical functions instead of ordinary spherical functions. The change of polar molecule ionization probability compared to non-polar molecule ionization is mainly due to constant change in the asymptotic form of the valence electron wave function, both in the dc and ac fields. We present numerical results for HF and HCl molecules of various isotopic proportions for specific orientations of the molecule axis relative to the electric field strength. The maximum rate of the tunnel effect for these molecules is achieved if the internuclear axis is oriented perpendicularly to the electric field. (paper)

  5. Raman investigation of tannin foams

    International Nuclear Information System (INIS)

    Full text: Tannin-based organic foams are new foam materials which are environmentally friendly, resistant to re and inexpensive, and intended to be used for building insulation, and also as water absorber or shock absorber. These foams can be produced via an acid catalyzed polycondensation reaction between condensed flavonoids and furfuryl alcohol. Several studies deal with the mechanism involved in this process, but some ambiguities still persist. Raman spectroscopy is an analytical technique suitable for the non-destructive chemical investigation of polymers, allowing to determine the presence of functional groups within a polymer through the interaction of laser light with the vibrational modes of the molecules setting up the sample under investigation. By this spectroscopic technique we have characterized the tannin-based foams and compared their spectral signature with that of tannins, and of polymerized furfuryl alcohol. Similarities and differences to the spectral features of carbonaceous material are discussed. (author)

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

    Science.gov (United States)

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

    2016-04-01

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

  7. An empirical evaluation of three vibrational spectroscopic methods for detection of aflatoxins in maize.

    Science.gov (United States)

    Lee, Kyung-Min; Davis, Jessica; Herrman, Timothy J; Murray, Seth C; Deng, Youjun

    2015-04-15

    Three commercially available vibrational spectroscopic techniques, including Raman, Fourier transform near infrared reflectance (FT-NIR), and Fourier transform infrared (FTIR) were evaluated to help users determine the spectroscopic method best suitable for aflatoxin analysis in maize (Zea mays L.) grain based on their relative efficiency and predictive ability. Spectral differences of Raman and FTIR spectra were more marked and pronounced among aflatoxin contamination groups than those of FT-NIR spectra. From the observations and findings in our current and previous studies, Raman and FTIR spectroscopic methods are superior to FT-NIR method in terms of predictive power and model performance for aflatoxin analysis and they are equally effective and accurate in predicting aflatoxin concentration in maize. The present study is considered as the first attempt to assess how spectroscopic techniques with different physical processes can influence and improve accuracy and reliability for rapid screening of aflatoxin contaminated maize samples.

  8. Rapid determination of pork sensory quality using Raman spectroscopy.

    Science.gov (United States)

    Wang, Qi; Lonergan, Steven M; Yu, Chenxu

    2012-07-01

    Existing objective methods to predict sensory attributes of pork in general do not yield satisfactory correlation to panel evaluations, and their applications in meat industry are limited. In this study, a Raman spectroscopic method was developed to evaluate and predict tenderness, juiciness and chewiness of fresh, uncooked pork loins from 169 pigs. Partial Least Square Regression models were developed based on Raman spectroscopic characteristics of the pork loins to predict the values of the sensory attributes. Furthermore, binary barcodes were created based on spectroscopic characteristics of the pork loins, and subjected to multivariate statistical discriminant analysis (i.e., Support Vector Machine) to differentiate and classify pork loins into quality grades ("good" and "bad" in terms of tenderness and chewiness). Good agreement (>83% correct predictions) with sensory panel results was obtained. The method developed in this report has the potential to become a rapid objective assay for tenderness and chewiness of pork products that may find practical applications in pork industry.

  9. Coherent Raman spectroscopy

    CERN Document Server

    Eesley, G L

    1981-01-01

    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

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

    Science.gov (United States)

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

    1980-01-01

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

  11. Ultrafast and nonlinear surface-enhanced Raman spectroscopy.

    Science.gov (United States)

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

    2016-04-21

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

  12. Confocal Raman Microscopy

    CERN Document Server

    Dieing, Thomas; Toporski, Jan

    2011-01-01

    Confocal Raman Microscopy is a relatively new technique that allows chemical imaging without specific sample preparation. By integrating a sensitive Raman spectrometer within a state-of-the-art microscope, Raman microscopy with a spatial resolution down to 200nm laterally and 500nm vertically can be achieved using visible light excitation. Recent developments in detector and computer technology as well as optimized instrument design have reduced integration times of Raman spectra by orders of magnitude, so that complete images consisting of tens of thousands of Raman spectra can be acquired in seconds or minutes rather than hours, which used to be standard just one decade ago. The purpose of this book is to provide the reader a comprehensive overview of the rapidly developing field of Confocal Raman Microscopy and its applications.

  13. Raman microspectroscopy for visualization of peripheral nerves

    Science.gov (United States)

    Minamikawa, Takeo; Harada, Yoshinori; Koizumi, Noriaki; Takamatsu, Tetsuro

    2013-02-01

    The peripheral nervous system plays an important role in motility, sensory, and autonomic functions of the human body. Preservation of peripheral nerves in surgery is essential for improving quality of life of patients. To preserve peripheral nerves, detection of ne peripheral nerves that cannot be identi ed by human eye or under white light imaging is necessary. In this study, we sought to provide a proof-of-principle demonstration of a label-free detection technique of peripheral nerve tissues against adjacent tissues that employs spontaneous Raman microspectroscopy. A line-illumination confocal Raman microscope was used for the experiment. A laser operating at the wavelength of 532 nm was used as an excitation laser light. We obtained Raman spectra of peripheral nerve, brous connective tissue, skeletal muscle, blood vessel, and adipose tissue of Wistar rats, and extracted speci c spectral features of peripheral nerves and adjacent tissues. By applying multivariate image analysis, peripheral nerves were clearly detected against adjacent tissues without any preprocessing neither xation nor staining. These results suggest the potential of the Raman spectroscopic observation for noninvasive and label-free nerve detection, and we expect this method could be a key technique for nerve-sparing surgery.

  14. Rotational Raman scattering in sup 127 I

    Energy Technology Data Exchange (ETDEWEB)

    Mondry, G.; Wissmann, F.; Mueller, G.; Schroeder, F.; Rullhusen, P.; Smend, F.; Schumacher, M. (2. Physikalisches Inst., Univ. Goettingen (Germany)); Fettweis, P.; Carchon, R. (Studiecentrum voor Kernenergie, Centre de l' Etudes de l' Energie Nucleaire, Mol (Belgium))

    1991-09-02

    Elastic and Raman scattering of photons by {sup 181}Ta and {sup 127}I are studied using the 11.4 MeV mono-energetic photon beam installed at the Mol BR2 reactor. For the strongly deformed prolate nucleus {sup 181}Ta the simple rotator model is re-investigated and found to be valid. The intrinsic quadrupole moment Q{sub 0} derived from spectroscopic data by assuming a strong particle-surface coupling was found to be in agreement with the splitting of the giant dipole resonance, thus removing previous inconsistencies. When applying the same model to the oblate nucleus {sup 127}I a severe discrepancy between experimental and predicted Raman cross sections was observed; this discrepancy is discussed in terms of nuclear-structure properties. (orig.).

  15. Characterization of Thalidomide using Raman Spectroscopy

    Science.gov (United States)

    Cipriani, Penelope; Smith, Candace Y.

    2008-02-01

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

  16. Design and analysis of new spectroscopic system of Raman lidar for detection of atmospheric water vapor∗%水汽探测拉曼激光雷达的新型光谱分光系统设计与分析*

    Institute of Scientific and Technical Information of China (English)

    王红伟; 华灯鑫; 王玉峰; 高朋; 赵虎

    2013-01-01

      提出并设计了一套新型的大气水汽和气溶胶探测用紫外域拉曼激光雷达系统,以二向色镜和超窄带滤光片构成高效率拉曼光谱分光系统,实现激光雷达大气回波信号中米-瑞利散射信号、氮气和水汽的振动拉曼散射信号的精细分离和高效率提取。利用美国标准大气的分子散射模型和实测的大气米散射信号模型,对分光系统的米-瑞利散射信号的抑制率、大气水汽测量的信噪比和误差进行数值仿真设计。搭建实验系统对西安地区夜间的大气水汽进行实验观测,并利用有云天气下实测的激光雷达回波信号,反演获得大气后向散射比和水汽混合比的相关特性,验证了该拉曼光谱分光系统对米-瑞利信号的抑制率达到10−7以上量级。理论和实验结果表明,设计的新型拉曼光谱分光系统可以在大气后向散射比为17时,实现水汽探测误差小于15%,满足拉曼激光雷达系统对大气水汽的高效率探测。%  A new ultraviolet Raman lidar system is proposed and developed for detecting atmospheric water vapor and aerosol study. The combination of dichroic mirrors and narrow-band interference filters is used as high-performance spectroscopic system to obtain the fine-separation and high-efficiency extraction of Mie-Rayleigh scattering signals, the vibrational Raman scattering signal of H2O and N2. By the American standard model and a set of atmospheric scattering signal model, the signal-to-noise ratio (SNR) and the water vapor measurement error are simulated and analyzed. The preliminary experiments are carried out at nighttime in Xi’an area for detecting the atmospheric water vapor and aerosols. Taking a set of the atmospheric returned signals measured under cloudy weather for example, the profiles of atmospheric backscatter ratio and water vapor mixing ratio are retrieved, and the SNR profiles of the three channels are discussed and

  17. 瞬态吸收和共振拉曼光谱研究硝基对联苯氮宾、氮宾离子反应活性的影响%Investigation of the Influence of Nitro-Substitution on the Reaction of Biphenyl-Nitrene and Nitrenium Ion by Transient Absorption and Resonance Raman Spectroscopic Techniques

    Institute of Scientific and Technical Information of China (English)

    李亚芳; 程博文; 沈超; 郑旭明; 薛佳丹; 杜勇; 汤文建

    2016-01-01

    利用光解芳基叠氮化合物得到单重态氮宾,运用纳秒瞬态吸收光谱、瞬态共振拉曼光谱实验手段,辅以密度泛函理论(DFT)计算,研究了4′-硝基-4-联苯氮宾在乙腈和水溶液中的光化学反应中间体。实验结果表明,在非质子溶剂中,4′-硝基-4-联苯氮宾发生系间窜越反应生成三线态氮宾;在质子溶剂中,单重态氮宾可被质子化产生氮宾离子。与4-联苯氮宾和氮宾离子相比,硝基对单重态氮宾系间窜越反应路径影响很小;降低了氮宾离子与水和叠氮阴离子的反应活性,却提高了其与鸟苷的反应活性。%Arylnitrenes and arylnitrenium ions are both short-lived intermediates that are highly reactive. In this work, nanosecond transient absorption and transient resonance Raman spectroscopic measurements were used to detect and identify the intermediates generated from the singlet 4′-nitro-4-biphenylnitrene after photolysis of the corresponding aryl azide in acetonitrile and aqueous solution. Combined with the density functional theory (DFT) simulation results, the structural and electronic characteristics of the above experimental intermediates were specified. The spectral results indicate that in aprotic solvents (such as acetonitrile), the singlet 4′-nitro-4-biphenylnitrene undergoes intersystem crossing (ISC) to the triplet nitrene. In contrast, in a protic solvent (such as the mixed aqueous solution used in this work), the singlet 4′-nitro-4-biphenylnitrene can be protonated to produce the nitrenium ion. Compared with its un-substituted counterpart, the nitro substitution has little influence on the ISC reaction pathway of the singlet 4-biphenylnitrene. With regard to the un-substituted nitrenium ion, the nitro group decreases its reactivity towards water and azide anion, while accelerating its reaction rate towards 2′-deoxyguanosine based on the different quench reaction rates between the nitrenium ion and

  18. Raman crystallography of RNA.

    Science.gov (United States)

    Gong, Bo; Chen, Jui-Hui; Yajima, Rieko; Chen, Yuanyuan; Chase, Elaine; Chadalavada, Durga M; Golden, Barbara L; Carey, Paul R; Bevilacqua, Philip C

    2009-10-01

    Raman crystallography is the application of Raman spectroscopy to single crystals. This technique has been applied to a variety of protein molecules where it has provided unique information about biopolymer folding, substrate binding, and catalysis. Here, we describe the application of Raman crystallography to functional RNA molecules. RNA represents unique opportunities and challenges for Raman crystallography. One issue that confounds studies of RNA is its tendency to adopt multiple non-functional folds. Raman crystallography has the advantage that it isolates a single state of the RNA within the crystal and can evaluate its fold, metal ion binding properties (ligand identity, stoichiometry, and affinity), proton binding properties (identity, stoichiometry, and affinity), and catalytic potential. In particular, base-specific stretches can be identified and then associated with the binding of metal ions and protons. Because measurements are carried out in the hanging drop at ambient, rather than cryo, conditions and because RNA crystals tend to be approximately 70% solvent, RNA dynamics and conformational changes become experimentally accessible. This review focuses on experimental setup and procedures, acquisition and interpretation of Raman data, and determination of physicochemical properties of the RNA. Raman crystallographic and solution biochemical experiments on the HDV RNA enzyme are summarized and found to be in excellent agreement. Remarkably, characterization of the crystalline state has proven to help rather than hinder functional characterization of functional RNA, most likely because the tendency of RNA to fold heterogeneously is limited in a crystalline environment. Future applications of Raman crystallography to RNA are briefly discussed.

  19. Portable raman explosives detection

    Energy Technology Data Exchange (ETDEWEB)

    Moore, David Steven [Los Alamos National Laboratory; Scharff, Robert J [Los Alamos National Laboratory

    2008-01-01

    Recent advances in portable Raman instruments have dramatically increased their application to emergency response and forensics, as well as homeland defense. This paper reviews the relevant attributes and disadvantages of portable Raman spectroscopy, both essentially and instrumentally, to the task of explosives detection in the field.

  20. Characterization of a hazardous eyeliner (kohl) by confocal Raman microscopy

    International Nuclear Information System (INIS)

    A new method of analyzing kohl, a cosmetic eyeliner, using confocal Raman microscopy is reported. This technique offers an important alternative to conventional spectroscopic techniques that provide elemental/atomic composition. Raman spectra of three kohl samples have been measured between 150 and 3000 cm-1 at room temperature. The main component of two kohl samples was found to be lead(II) sulfide (PbS). Kohl is used as a traditional cosmetic and remedy in the Middle East, Far East, and Northern Africa. Since kohl products contain very high concentrations of lead, they constitute a risk for public health, particularly for children