WorldWideScience

Sample records for raman scattering spectra

  1. Raman spectra of lithium compounds

    Science.gov (United States)

    Gorelik, V. S.; Bi, Dongxue; Voinov, Y. P.; Vodchits, A. I.; Gorshunov, B. P.; Yurasov, N. I.; Yurasova, I. I.

    2017-11-01

    The paper is devoted to the results of investigating the spontaneous Raman scattering spectra in the lithium compounds crystals in a wide spectral range by the fibre-optic spectroscopy method. We also present the stimulated Raman scattering spectra in the lithium hydroxide and lithium deuteride crystals obtained with the use of powerful laser source. The symmetry properties of the lithium hydroxide, lithium hydroxide monohydrate and lithium deuteride crystals optical modes were analyzed by means of the irreducible representations of the point symmetry groups. We have established the selection rules in the Raman and infrared absorption spectra of LiOH, LiOH·H2O and LiD crystals.

  2. Raman spectra of graphene ribbons

    International Nuclear Information System (INIS)

    Saito, R; Furukawa, M; Dresselhaus, G; Dresselhaus, M S

    2010-01-01

    Raman spectra of graphene nanoribbons with zigzag and armchair edges are calculated within non-resonant Raman theory. Depending on the edge structure and polarization direction of the incident and scattered photon beam relative to the edge direction, a symmetry selection rule for the phonon type appears. These Raman selection rules will be useful for the identification of the edge structure of graphene nanoribbons.

  3. Manifestation of hydrogen bonds of aqueous ethanol solutions in the Raman scattering spectra

    International Nuclear Information System (INIS)

    Dolenko, T A; Burikov, S A; Patsaeva, S V; Yuzhakov, V I

    2011-01-01

    Spectra of Raman scattering of light by aqueous ethanol solutions in the range of concentrations from pure water to 96% alcohol are studied. For water, 25%, and 40% solutions of ethanol in water, as well as for 96% alcohol the Raman spectra are measured at temperatures from the freezing point to nearly the boiling point. The changes in the shape of the stretching OH band are interpreted in terms of strengthening or weakening of hydrogen bonds between the molecules in the solution. The strongest hydrogen bonding of hydroxyl groups is observed at the ethanol content from 20 to 25 volume percent, which is explained by formation of ethanol hydrates of a definite type at the mentioned concentrations of alcohol. This is confirmed by means of the method of multivariate curve resolution, used to analyse the Raman spectra of aqueous ethanol solutions. With growing temperature the weakening of hydrogen bonding occurs in all studied systems, which consists in reducing the number of OH groups, linked by strong hydrogen bonds. (laser applications and other problems in quantum electronics)

  4. Raman scattering of Cisplatin near silver nanoparticles

    Science.gov (United States)

    Mirsaleh-Kohan, Nasrin; Duplanty, Michael; Torres, Marjorie; Moazzezi, Mojtaba; Rostovtsev, Yuri V.

    2018-03-01

    The Raman scattering of Cisplatin (the first generation of anticancer drugs) has been studied. In the presence of silver nanoparticles, strong modifications of Raman spectra have been observed. The Raman frequencies have been shifted and the line profiles are broadened. We develop a theoretical model to explain the observed features of the Raman scattering. The model takes into account self-consistently the interaction of molecules with surface plasmonic waves excited in the silver nanoparticles, and it provides a qualitative agreement with the observed Raman spectra. We have demonstrated that the using silver nanoparticles can increase sensitivity of the technique, and potentially it has a broader range of applications to both spectroscopy and microscopy.

  5. Characterization of Materials by Raman Scattering

    Science.gov (United States)

    Kozielski, M.

    2007-03-01

    The paper reports on the use of phonon spectra obtained with the Raman spectroscopy for characterization of different materials. The Raman scattering spectra obtained for zinc selenide crystals, mixed crystals zinc selenide admixtured with magnesium or beryllium, oxide crystals including strontium lanthanum gallate, molecular crystals of triammonium hydrogen diseleniate and a homologous series of polyoxyethylene glycols are analysed.

  6. Transport properties and Raman spectra of impurity substituted MgB2

    International Nuclear Information System (INIS)

    Masui, T.

    2007-01-01

    Recent advances in the study of MgB 2 are reviewed, with focus on the transport properties and Raman scattering measurements for impurity substituted crystals. Carbon and Aluminium substitution change band filling, introduce intraband and interband scattering. These effects are seen in the temperature dependence of resistivity, Hall coefficients, and phonon peak of Raman spectra. Manganese substitution introduces magnetic scattering, that increases resistivity but gives little change in Raman spectra. The effect of disorder in neutron irradiated samples is also discussed

  7. Electron Raman scattering in asymmetrical multiple quantum wells

    International Nuclear Information System (INIS)

    Betancourt-Riera, R; Rosas, R; Marin-Enriquez, I; Riera, R; Marin, J L

    2005-01-01

    Optical properties of asymmetrical multiple quantum wells for the construction of quantum cascade lasers are calculated, and expressions for the electronic states of asymmetrical multiple quantum wells are presented. The gain and differential cross-section for an electron Raman scattering process are obtained. Also, the emission spectra for several scattering configurations are discussed, and the corresponding selection rules for the processes involved are studied; an interpretation of the singularities found in the spectra is given. The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers

  8. Theory of Graphene Raman Scattering.

    Science.gov (United States)

    Heller, Eric J; Yang, Yuan; Kocia, Lucas; Chen, Wei; Fang, Shiang; Borunda, Mario; Kaxiras, Efthimios

    2016-02-23

    Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly.

  9. Coherent Raman scattering: Applications in imaging and sensing

    Science.gov (United States)

    Cui, Meng

    In this thesis, I discuss the theory, implementation and applications of coherent Raman scattering to imaging and sensing. A time domain interferometric method has been developed to collect high resolution shot-noise-limited Raman spectra over the Raman fingerprint regime and completely remove the electronic background signal in coherent Raman scattering. Compared with other existing coherent Raman microscopy methods, this time domain approach is proved to be simpler and more robust in rejecting background signal. We apply this method to image polymers and biological samples and demonstrate that the same setup can be used to collect two photon fluorescence and self phase modulation signals. A signal to noise ratio analysis is performed to show that this time domain method has a comparable signal to noise ratio to spectral domain methods, which we confirm experimentally. The coherent Raman method is also compared with spontaneous Raman scattering. The conditions under which coherent methods provide signal enhancement are discussed and experiments are performed to compare coherent Raman scattering with spontaneous Raman scattering under typical biological imaging conditions. A critical power, above which coherent Raman scattering is more sensitive than spontaneous Raman scattering, is experimentally determined to be ˜1mW in samples of high molecule concentration with a 75MHz laser system. This finding is contrary to claims that coherent methods provide many orders of magnitude enhancement under comparable conditions. In addition to the far field applications, I also discuss the combination of our time domain coherent Raman method with near field enhancement to explore the possibility of sensing and near field imaging. We report the first direct time-resolved coherent Raman measurement performed on a nanostructured substrate for molecule sensing. The preliminary results demonstrate that sub 20 fs pulses can be used to obtain coherent Raman spectra from a small number

  10. Characterization of excited electronic states of naphthalene by resonance Raman and hyper-Raman scattering

    International Nuclear Information System (INIS)

    Bonang, C.C.; Cameron, S.M.

    1992-01-01

    The first resonance Raman and hyper-Raman scattering from naphthalene are reported. Fourth harmonic of a mode-locked Nd:YAG laser is used to resonantly excite the 1 B 1u + transition, producing Raman spectra that confirm the dominance of the vibronically active ν 28 (b 3g ) mode and the Franck--Condon active a g modes, ν 5 and ν 3 . A synchronously pumped stilbene dye laser and its second harmonic are employed as the excitation sources for hyper-Raman and Raman scattering from the overlapping 1 B 2 u + and 1 A g - states. The Raman spectra indicate that the equilibrium geometry of naphthalene is distorted primarily along ν 5 , ν 8 , and ν 7 normal coordinates upon excitation to 1 B 2 u + . The hyper-Raman spectrum shows that ν 25 (b 2u ) is the mode principally responsible for vibronic coupling between the 1 A g - and 1 B 2u + states. The results demonstrate the advantageous features of resonance hyper-Raman scattering for the case of overlapping one- and two-photon allowed transitions. Calculations based on simple molecular orbital configurations are shown to qualitatively agree with the experimental results

  11. Infrared dispersion analysis and Raman scattering spectra of taurine single crystals

    Science.gov (United States)

    Moreira, Roberto L.; Lobo, Ricardo P. S. M.; Dias, Anderson

    2018-01-01

    A comprehensive set of optical vibrational modes of monoclinic taurine crystals was determined by Raman scattering, and infrared reflectivity and transmission spectroscopies. By using appropriate scattering/reflection geometries, the vibrational modes were resolved by polarization and the most relevant modes of the crystal could be assigned. In particular, we were able to review the symmetry of the gerade modes and to resolve ambiguities in the literature. Owing to the non-orthogonal character of Bu modes in monoclinic crystals (lying on the optic axial plane), we carried out a generalized Lorentz dispersion analysis consisting of simultaneous adjust of infrared-reflectivity spectra at various light polarization angles. The Au modes (parallel to the C2-axis) were treated within the classical Lorentz model. The behavior of off-diagonal and diagonal terms of the complex dielectric tensors and the presence of anomalous dispersion were discussed as consequences of the low symmetry of the crystal.

  12. Comparison of Surface-enhanced Raman Scattering Spectra of Two Kinds of Silver Nanoplate Films

    Institute of Scientific and Technical Information of China (English)

    TAO Jin-long; TANG Bin; XU Shu-ping; PAN Ling-yun; XU Wei-qing

    2012-01-01

    Surface-enhanced Raman scattering(SERS) spectra of different silver nanoplate self-assembled films at different excitation wavelengths were fairly compared.Shape conversion from silver nanoprisms to nanodisks on slides was in situ carried out.The SERS spectra of 4-mercaptopyridine(4-MPY) on these anisotropic silver nanoparticle self-assembled films present that strong enhancement appeared when the excitation line and the surface plasmon resonance(SPR) band of silver substrate overlapped.In this model,the influence of the crystal planes of silver nanoplates on SERS enhancement could be ignored because the basal planes were nearly unchanged in two kinds of silver nanoplate self-assembled films.

  13. Raman scattering in condensed media placed in photon traps

    Science.gov (United States)

    Goncharov, A. P.; Gorelik, V. S.; Krawtsow, A. V.

    2007-11-01

    A new type of resonator cells (photon traps) has been worked out, which ensures the Raman opalescence regime (i.e., the conditions under which the relative Raman scattering intensity at the outlet of the cells increases significantly as compared to the exciting line intensity. The Raman scattering spectra of a number of organic and inorganic compounds placed in photon traps are studied under pulse-periodic excitation by a copper-vapor laser.

  14. Raman Spectra of Methane, Ethylene, Ethane, Dimethyl ether, Formaldehyde and Propane for Combustion Applications

    KAUST Repository

    Magnotti, G.

    2015-05-09

    Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

  15. Raman Spectra of Methane, Ethylene, Ethane, Dimethyl ether, Formaldehyde and Propane for Combustion Applications

    KAUST Repository

    Magnotti, G.; KC, Utsav; Varghese, P.L.; Barlow, R.S.

    2015-01-01

    Spontaneous Raman scattering measurements of temperature and major species concentration in hydrocarbon-air flames require detailed knowledge of the Raman spectra of the hydrocarbons present when fuels more complex than methane are used. Although hydrocarbon spectra have been extensively studied at room temperature, there are no data available at higher temperatures. Quantum mechanical calculations, when available are not sufficiently accurate for combustion applications. This work presents experimental measurements of spontaneous Stokes-Raman scattering spectra of methane, ethylene, ethane, dimethyl ether, formaldehyde and propane in the temperature range 300-860 K. Raman spectra from heated hydrocarbons jets have been collected with a higher resolution than is generally employed for Raman measurements in combustion applications. A set of synthetic spectra have been generated for each hydrocarbon, providing the basis for extrapolation to higher temperatures. The spectra provided here will enable simultaneous measurements of multiple hydrocarbons in flames. This capability will greatly extend the range of applicability of Raman measurements in combustion applications. In addition, the experimental spectra provide a validation dataset for quantum mechanical models.

  16. Raman scattering of rare earth hexaborides

    International Nuclear Information System (INIS)

    Ogita, Norio; Hasegawa, Takumi; Udagawa, Masayuki; Iga, Fumitoshi; Kunii, Satoru

    2009-01-01

    Raman scattering spectra were measured for the rare-earth hexaborides RB 6 (R = Ce, Gd, or Dy). All Raman-active phonons due to B 6 vibrations were observed in the range 600 - 1400 cm -1 . Anomalous peaks were detected below 200 cm -1 , which correspond to vibrations of rare-earth ion excited by second-order Raman scattering process. The intensity and energy of the rare-earth mode decrease with decreasing temperature. This suggests that the rare-earth ion vibrates in a shallow and anharmonic potential due to the boron cage. Using the reported values of mean square displacement of rare-earth ion, we estimated the anharmonic contribution for the rare-earth vibrations.

  17. Electron enhanced Raman scattering and its applications in solution chemistry

    International Nuclear Information System (INIS)

    Yui, Hiroharu

    2007-01-01

    The present review describes a new enhancement technique for Raman scattering in aqueous solutions. Raman scattering spectroscopy has an inherent ability to distinguish between molecules with great similarity and provides useful information on local physical and chemical environments at their functional groups' level. Since the Raman scattering signals from water molecules are quite weak, Raman spectroscopy has great advantage for detection or discrimination of a trace amount of analytes in aqueous environments. However, Raman scattering cross-sections are inherently small and it generally requires high power excitation and long acquisition times to obtain high-quality Raman spectra. These conditions create disadvantages for the analyses for living cells and real-time monitoring for environmental analyses. Here, I describe a new Raman enhancement technique, namely electron enhanced Raman scattering (EERS)', where artificially generated electrons additionally affect the polarizability of target molecular systems and enhance their inherent Raman cross-section. Principles of the EERS and its applications to aqueous solution are presented. (author)

  18. Raman scattering of monolayer graphene: the temperature and oxygen doping effects

    International Nuclear Information System (INIS)

    Zhou Haiqing; Qiu Caiyu; Yu Fang; Yang Huaichao; Chen Minjiang; Hu Lijun; Guo Yanjun; Sun Lianfeng

    2011-01-01

    Raman spectra of monolayer graphene at various temperatures (303-473 K) are measured. In Raman scattering with wave numbers ranging from 1200 to 3400 cm -1 , the four main Raman peaks (G, 2D, T + D and 2D') show temperature-dependent behaviour, but have different frequency shifts with increase in temperature. We propose that the peak frequency shift is related mainly to the elongation of C-C bond due to thermal expansion or anharmonic coupling of phonon modes, and oxygen-induced strong hole doping on the graphene surface. The doping effect can be confirmed from the frequency shifts, full-width at half-maximum as well as the area and intensity ratios of G and 2D peaks in temperature-dependent Raman scattering of graphene, room-temperature Raman spectra of pristine graphene and graphene cooled down after Raman measurement at 473 K in air. Therefore, the oxygen doping effect and temperature effect coexist in temperature-dependent Raman scattering of monolayer graphene.

  19. Raman scattering and luminescence of high-Tc superconducting oxides

    International Nuclear Information System (INIS)

    Eremenko, V.V.; Gnezdilov, V.P.; Fomin, V.I.; Fugol', I.Ya.; Samovarov, V.N.

    1989-01-01

    Raman and luminescence spectra of high-T c superconducting oxides are summarized, mainly YBa 2 Cu 3 O 7-σ and partly La 2-x Ba x CuO 4-σ . In raman spectra we succeeded to distinguish electron scattering to define the energy gap Δ in the superconducting state. The luminescence spectra are due to the emission of oxygen and interaction with conduction electrons. 70 refs.; 13 figs

  20. Phonon-induced anomalous Raman spectra in undoped high-Tc cuprates

    International Nuclear Information System (INIS)

    Lee, J.D.; Min, B.I.

    1997-01-01

    In order to describe a shoulder peak structure near 4J in the magnon Raman spectra of undoped high-T c cuprates, we have explored the phonon contribution to the Raman spectra. Incorporating the magnon-phonon Hamiltonian in the spin-wave theory, we have evaluated the two-magnon Raman spectral function originating from the lowest-order magnon-phonon-magnon scattering. It is found that phonons induce a shoulder peak near 4J besides the dominant two-magnon peak near 3J, in agreement with experiments. (orig.)

  1. Vibronic spectra of Gd3+ in metaphosphate glasses: Comparison with Raman and infrared spectra

    International Nuclear Information System (INIS)

    Hall, D.W.; Brawer, S.A.; Weber, M.J.

    1982-01-01

    Vibronic sidebands associated with the 6 P/sub 7/2/→ 8 S/sub 7/2/ transition of Gd 3+ -doped metaphosphate glasses are observed using line-narrowed fluorescence techniques. Glasses having metal cations of different mass and charge (La,Al,Mg,Ba) are examined. Vibronic spectra, which probe vibrations about the rare-earth element site, are compared with polarized Raman scattering data and the infrared dielectric constant obtained from near-normal reflectance measurements. Results indicate that in metaphosphate glasses vibronic selection rules are similar to HV (vertical height) Raman selection rules. The wavelengths and relative intensities of peaks in the high-frequency portion of the vibronic spectra change with respect to corresponding peaks in the Raman spectra when the mass and/or charge of Gd 3+ differs significantly from that of the metal cation

  2. Raman spectra of thiolated arsenicals with biological importance.

    Science.gov (United States)

    Yang, Mingwei; Sun, Yuzhen; Zhang, Xiaobin; McCord, Bruce; McGoron, Anthony J; Mebel, Alexander; Cai, Yong

    2018-03-01

    Surface enhanced Raman scattering (SERS) has great potential as an alternative tool for arsenic speciation in biological matrices. SERS measurements have advantages over other techniques due to its ability to maintain the integrity of arsenic species and its minimal requirements for sample preparation. Up to now, very few Raman spectra of arsenic compounds have been reported. This is particularly true for thiolated arsenicals, which have recently been found to be widely present in humans. The lack of data for Raman spectra in arsenic speciation hampers the development of new tools using SERS. Herein, we report the results of a study combining the analysis of experimental Raman spectra with that obtained from density functional calculations for some important arsenic metabolites. The results were obtained with a hybrid functional B3LYP approach using different basis sets to calculate Raman spectra of the selected arsenicals. By comparing experimental and calculated spectra of dimethylarsinic acid (DMA V ), the basis set 6-311++G** was found to provide computational efficiency and precision in vibrational frequency prediction. The Raman frequencies for the rest of organoarsenicals were studied using this basis set, including monomethylarsonous acid (MMA III ), dimethylarsinous acid (DMA III ), dimethylmonothioarinic acid (DMMTA V ), dimethyldithioarsinic acid (DMDTA V ), S-(Dimethylarsenic) cysteine (DMA III (Cys)) and dimethylarsinous glutathione (DMA III GS). The results were compared with fingerprint Raman frequencies from As─O, As─C, and As─S obtained under different chemical environments. These fingerprint vibrational frequencies should prove useful in future measurements of different species of arsenic using SERS. Copyright © 2017 Elsevier B.V. All rights reserved.

  3. Electron states and electron Raman scattering in semiconductor double cylindrical quantum well wire

    International Nuclear Information System (INIS)

    Munguía-Rodríguez, M; Riera, R; Betancourt-Riera, Ri; Betancourt-Riera, Re; Nieto Jalil, J M

    2016-01-01

    The differential cross section for an electron Raman scattering process in a semiconductor GaAs/AlGaAs double quantum well wire is calculated, and expressions for the electronic states are presented. The system is modeled by considering T = 0 K and also with a single parabolic conduction band, which is split into a subband system due to the confinement. The gain and differential cross-section for an electron Raman scattering process are obtained. In addition, the emission spectra for several scattering configurations are discussed, and interpretations of the singularities found in the spectra are given. The electron Raman scattering studied here can be used to provide direct information about the efficiency of the lasers. (paper)

  4. Reduction of Raman scattering and fluorescence from anvils in high pressure Raman scattering

    Science.gov (United States)

    Dierker, S. B.; Aronson, M. C.

    2018-05-01

    We describe a new design and use of a high pressure anvil cell that significantly reduces the Raman scattering and fluorescence from the anvils in high pressure Raman scattering experiments. The approach is particularly useful in Raman scattering studies of opaque, weakly scattering samples. The effectiveness of the technique is illustrated with measurements of two-magnon Raman scattering in La2CuO4.

  5. Coherent anti-Stokes Raman scattering and spontaneous Raman scattering diagnostics of nonequilibrium plasmas and flows

    Science.gov (United States)

    Lempert, Walter R.; Adamovich, Igor V.

    2014-10-01

    The paper provides an overview of the use of coherent anti-Stokes Raman scattering (CARS) and spontaneous Raman scattering for diagnostics of low-temperature nonequilibrium plasmas and nonequilibrium high-enthalpy flows. A brief review of the theoretical background of CARS, four-wave mixing and Raman scattering, as well as a discussion of experimental techniques and data reduction, are included. The experimental results reviewed include measurements of vibrational level populations, rotational/translational temperature, electric fields in a quasi-steady-state and transient molecular plasmas and afterglow, in nonequilibrium expansion flows, and behind strong shock waves. Insight into the kinetics of vibrational energy transfer, energy thermalization mechanisms and dynamics of the pulse discharge development, provided by these experiments, is discussed. Availability of short pulse duration, high peak power lasers, as well as broadband dye lasers, makes possible the use of these diagnostics at relatively low pressures, potentially with a sub-nanosecond time resolution, as well as obtaining single laser shot, high signal-to-noise spectra at higher pressures. Possibilities for the development of single-shot 2D CARS imaging and spectroscopy, using picosecond and femtosecond lasers, as well as novel phase matching and detection techniques, are discussed.

  6. Electron Raman scattering in semiconductor quantum wire in an external magnetic field

    International Nuclear Information System (INIS)

    Betancourt-Riera, Ri; Nieto Jalil, J M; Riera, R; Betancourt-Riera, Re; Rosas, R

    2008-01-01

    The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement is calculated. We assume a single parabolic conduction band. The emission spectra for different scattering configurations and the selection rules for the processes are studied. Singularities in the spectra are found and interpreted. The electron Raman scattering studied here can be used to provide direct information about the electron band and subband structure of these confinement systems. The magnetic field distribution is considered constant with value B 0 inside the wire and zero outside

  7. Simulations and analysis of the Raman scattering and differential Raman scattering/Raman optical activity (ROA) spectra of amino acids, peptides and proteins in aqueous solution

    DEFF Research Database (Denmark)

    Jalkanen, Karl J.; Nieminen, R. M.; Bohr, Jakob

    2000-01-01

    The Raman and Raman optical activity (ROA) spectra of amino acids and small peptides in aqueous solution have been simulated by density functional theory and restricted Hartree/Fock methods. The treatment of the aqueous environment in treated in two ways. The water molecules in the first hydratio...

  8. RAMAN SCATTERING BY MOLECULAR HYDROGEN AND NITROGEN IN EXOPLANETARY ATMOSPHERES

    Energy Technology Data Exchange (ETDEWEB)

    Oklopčić, Antonija [California Institute of Technology, MC 249-17, 1200 East California Boulevard, Pasadena, California 91125 (United States); Hirata, Christopher M. [Center for Cosmology and Astroparticle Physics, Ohio State University, 191 West Woodruff Avenue, Columbus, Ohio 43210 (United States); Heng, Kevin, E-mail: oklopcic@astro.caltech.edu [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland)

    2016-11-20

    An important source of opacity in exoplanet atmospheres 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. We analyze the signatures of Raman scattering imprinted in the reflected light and the geometric albedo of exoplanets, which could provide information about atmospheric properties. Raman scattering affects the geometric albedo spectra of planets in the following ways. First, it causes filling-in of strong absorption lines in the incident radiation, thus producing sharp peaks in the albedo. Second, it shifts the wavelengths of spectral features in the reflected light causing the so-called Raman ghost lines. Raman scattering can also cause a broadband reduction of the albedo due to wavelength shifting of a stellar spectrum with red spectral index. Observing the Raman peaks in the albedo could be used to measure the column density of gas, thus providing constraints on the presence of clouds in the atmosphere. Observing the Raman ghost lines could be used to spectroscopically identify the main scatterer in the atmosphere, even molecules like H{sub 2} or N{sub 2}, which do not have prominent spectral signatures in the optical wavelength range. If detected, ghost lines could also provide information about the temperature of the atmosphere. In this paper, we investigate the effects of Raman scattering in hydrogen- and nitrogen-dominated atmospheres. We analyze the feasibility of detecting the signatures of Raman scattering with the existing and future observational facilities, and of using these signatures as probes of exoplanetary atmospheres.

  9. Optimizing laser crater enhanced Raman scattering spectroscopy

    Science.gov (United States)

    Lednev, V. N.; Sdvizhenskii, P. A.; Grishin, M. Ya.; Fedorov, A. N.; Khokhlova, O. V.; Oshurko, V. B.; Pershin, S. M.

    2018-05-01

    The laser crater enhanced Raman scattering (LCERS) spectroscopy technique has been systematically studied for chosen sampling strategy and influence of powder material properties on spectra intensity enhancement. The same nanosecond pulsed solid state Nd:YAG laser (532 nm, 10 ns, 0.1-1.5 mJ/pulse) was used for laser crater production and Raman scattering experiments for L-aspartic acid powder. Increased sampling area inside crater cavity is the key factor for Raman signal improvement for the LCERS technique, thus Raman signal enhancement was studied as a function of numerous experimental parameters including lens-to-sample distance, wavelength (532 and 1064 nm) and laser pulse energy utilized for crater production. Combining laser pulses of 1064 and 532 nm wavelengths for crater ablation was shown to be an effective way for additional LCERS signal improvement. Powder material properties (particle size distribution, powder compactness) were demonstrated to affect LCERS measurements with better results achieved for smaller particles and lower compactness.

  10. Variation of Raman spectra of CdSe/ZnS quantum dots at the bioconjugation

    Energy Technology Data Exchange (ETDEWEB)

    Macotela, L.G.V.; Douda, J. [UPIITA - Instituto Politecnico Nacional, Mexico (Mexico); Torchynska, T.V. [ESFM - Instituto Politecnico Nacional, Mexico (Mexico); Sierra, R.P. [CINVESTAV del IPN, Mexico (Mexico)

    2010-04-15

    This paper presents the results of comparative analysis of Raman scattering spectra of CdSe/ZnS QDs covered by polymer with and without bio-conjugation to the mouse anti PSA (Prostate-Specific Antigen) antibodies (mab). Commercial CdSe/ZnS QDs used in the study are characterized by the color emission with the maximum at 565 nm (2.19 eV) at 300 K. Raman scattering spectra measured at room temperature demonstrate two groups of peaks: (i) related to the Si substrate at 230-460, 522, 610, 670, 940-1040 cm{sup -1} and (2) to polymer on the QD surface in the spectral range 1268-3310 cm{sup -1}. It is revealed that the QD bio-conjugation to the anti PSA mab is accompanied by the variation dramatically in the intensity of Raman lines of both types. The explanation of Raman peak stimulation in bio-conjugated QDs has been proposed on the base of surface enhanced Raman scattering (SERS) effect (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  11. Molecular selectivity of graphene-enhanced Raman scattering.

    Science.gov (United States)

    Huang, Shengxi; Ling, Xi; Liang, Liangbo; Song, Yi; Fang, Wenjing; Zhang, Jin; Kong, Jing; Meunier, Vincent; Dresselhaus, Mildred S

    2015-05-13

    Graphene-enhanced Raman scattering (GERS) is a recently discovered Raman enhancement phenomenon that uses graphene as the substrate for Raman enhancement and can produce clean and reproducible Raman signals of molecules with increased signal intensity. Compared to conventional Raman enhancement techniques, such as surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS), in which the Raman enhancement is essentially due to the electromagnetic mechanism, GERS mainly relies on a chemical mechanism and therefore shows unique molecular selectivity. In this paper, we report graphene-enhanced Raman scattering of a variety of different molecules with different molecular properties. We report a strong molecular selectivity for the GERS effect with enhancement factors varying by as much as 2 orders of magnitude for different molecules. Selection rules are discussed with reference to two main features of the molecule, namely its molecular energy levels and molecular structures. In particular, the enhancement factor involving molecular energy levels requires the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies to be within a suitable range with respect to graphene's Fermi level, and this enhancement effect can be explained by the time-dependent perturbation theory of Raman scattering. The enhancement factor involving the choice of molecular structures indicates that molecular symmetry and substituents similar to that of the graphene structure are found to be favorable for GERS enhancement. The effectiveness of these factors can be explained by group theory and the charge-transfer interaction between molecules and graphene. Both factors, involving the molecular energy levels and structural symmetry of the molecules, suggest that a remarkable GERS enhancement requires strong molecule-graphene coupling and thus effective charge transfer between the molecules and graphene. These conclusions are further

  12. Coherent Raman scattering in high-pressure/high-temperature fluids: An overview

    International Nuclear Information System (INIS)

    Schmidt, S.C.; Moore, D.S.

    1990-01-01

    The present understanding of high-pressure/high-temperature dense-fluid behavior is derived almost exclusively from hydrodynamic and thermodynamic measurements. Such results average over the microscopic aspects of the materials and are, therefore, insufficient for a complete understanding of fluid behavior. At the present, dense-fluid models can be verified only to the extend that they agree with the macroscopic measurements. Recently, using stimulated Raman scattering, Raman induced Kerr effect scattering, and coherent anti-Stokes Raman scattering, we have been able to probe some of the microscopic phenomenology of these dense fluids. In this paper, we discuss primarily the use of CARS in conjunction with a two-stage light-gas gun to obtain vibrational spectra of shock-compressed liquid N 2 , O 2 , CO, their mixtures, CH 3 NO 2 , and N 2 O. These experimental spectra are compared to synthetic spectra calculated using a semiclassical model for CARS intensities and best fit vibrational frequencies, peak Raman susceptibilities, and Raman linewidths. For O 2 , the possibility of resonance enhancement from collision-induced absorption is addressed. Shifts in the vibrational frequencies reflect the influence of increased density and temperature on the intramolecular motion. The derived parameters suggest thermal equilibrium of the vibrational levels is established less than a few nanoseconds after shock passage. Vibrational temperatures are obtained that agree with those derived from equation-of-state calculations. Measured linewidths suggest that vibrational dephasing times have decreased to subpicosecond values at the highest shock pressures

  13. Contrastive Analysis of the Raman Spectra of Polychlorinated Benzene: Hexachlorobenzene and Benzene

    Directory of Open Access Journals (Sweden)

    Zhengjun Zhang

    2011-12-01

    Full Text Available Detection of persistent pollutants such as polychlorinated benzene in environment in trace amounts is challenging, but important. It is more difficult to distinguish homologues and isomers of organic pollutantd when present in trace amounts because of their similar physical and chemical properties. In this work we simulate the Raman spectra of hexachlorobenzene and benzene, and figure out the vibration mode of each main peak. The effect on the Raman spectrum of changing substituents from H to Cl is analyzed to reveal the relations between the Raman spectra of homologues and isomers of polychlorinated benzene, which should be helpful for distinguishing one kind of polychlorinated benzene from its homologues and isomers by surface enhanced Raman scattering.

  14. Electronic Raman scattering with excitation between localized states observed in the zinc M{sub 2,3} soft x-ray spectra of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, L.; Callcott, T.A.; Jia, J.J. [Univ. of Tennessee, Knoxville, TN (United States)] [and others

    1997-04-01

    Zn M{sub 2,3} soft x-ray fluorescence (SXF) spectra of ZnS and ZnS{sub .5}Se{sub .5} excited near threshold show strong inelastic scattering effects that can be explained using a simple model and an inelastic scattering theory based on second order perturbation theory. This scattering is often called electronic resonance Raman scattering. Tulkki and Aberg have developed this theory in detail for atomic systems, but their treatment can be applied to solid systems by utilizing electronic states characteristic of solids rather than of atomic systems.

  15. Electron Raman scattering in semiconductor quantum well wire of cylindrical ring geometry

    International Nuclear Information System (INIS)

    Betancourt-Riera, Re.; Betancourt-Riera, Ri.; Nieto Jalil, J. M.; Riera, R.

    2015-01-01

    We study the electron states and the differential cross section for an electron Raman scattering process in a semiconductor quantum well wire of cylindrical ring geometry. The electron Raman scattering developed here can be used to provide direct information about the electron band structures of these confinement systems. We assume that the system grows in a GaAs/Al 0.35 Ga 0.65 As matrix. The system is modeled by considering T = 0 K and also a single parabolic conduction band, which is split into a sub-band system due to the confinement. The emission spectra are discussed for different scattering configurations, and the selection rules for the processes are also studied. Singularities in the spectra are found and interpreted. (paper)

  16. A study of photoluminescence and micro-Raman scattering in C-implanted GaN

    International Nuclear Information System (INIS)

    Zhang Limin; Zhang Xiaodong; Liu Zhengmin

    2010-01-01

    GaN samples (no yellow luminescence) in their as-grown states were implanted with 10 13 -10 17 C ions/cm 2 and studied by photoluminescence spectra and micro-Raman scattering spectra. The photoluminescence study showed that yellow luminescence were produced in the C-implanted GaN after 950 degree C annealing, and the peaks of the near band edge emissions showed blue-shifts after C implantation. The Raman measurements indicated that the stresses in GaN films did not change after C implantation. The samples implanted with 10 15 cm -2 carbon ions had the Raman peak at 300 cm -1 , which is associated to the disorder-activated Raman scattering. However, further increasing the implantation dose resulted decreased intensity of the 300 cm -1 peak, due to the ion beam current increase with the implantation dose. (authors)

  17. Utilizing Raman Spectroscopy and Surface-Enhanced Raman Spectroscopy to investigate healthy and cancerous colon samples

    International Nuclear Information System (INIS)

    Barzegar, A.; Rezaei, H.; Malekfar, R.

    2012-01-01

    In this study, spontaneous Raman scattering and surface-enhanced Raman scattering, Surface-Enhanced Raman Spectroscopy spectra have been investigated. The samples which were kept in the formalin solution selected from the human's healthy and cancerous colon tissues. The Surface-Enhanced Raman Spectroscopy spectra were collected by adding colloidal solution contained silver nanoparticles to the top of the samples. The recorded spectra were compared for the spontaneous Raman spectra of healthy and cancerous colon samples. The spontaneous and surface enhanced Raman scattering data were also collected and compared for both healthy and damaged samples.

  18. Wavelength modulated surface enhanced (resonance) Raman scattering for background-free detection.

    Science.gov (United States)

    Praveen, Bavishna B; Steuwe, Christian; Mazilu, Michael; Dholakia, Kishan; Mahajan, Sumeet

    2013-05-21

    Spectra in surface-enhanced Raman scattering (SERS) are always accompanied by a continuum emission called the 'background' which complicates analysis and is especially problematic for quantification and automation. Here, we implement a wavelength modulation technique to eliminate the background in SERS and its resonant version, surface-enhanced resonance Raman scattering (SERRS). This is demonstrated on various nanostructured substrates used for SER(R)S. An enhancement in the signal to noise ratio for the Raman bands of the probe molecules is also observed. This technique helps to improve the analytical ability of SERS by alleviating the problem due to the accompanying background and thus making observations substrate independent.

  19. Electron Raman scattering in quantum well wires

    International Nuclear Information System (INIS)

    Zhao Xiangfu; Liu Cuihong

    2007-01-01

    Electron Raman scattering (ERS) is investigated in a semiconductor quantum well wire (QWW) of cylindrical geometry for T=0K and neglecting phonon-assisted transitions. The differential cross-section (DCS) involved in this process is calculated as a function of a scattering frequency and the cylindrical radius. Electron states are confined within a QWW. Single parabolic conduction and valence bands are assumed. The selection rules are studied. Singularities in the spectra are interpreted for various cylindrical radii. ERS discussed here can provide direct information about the electron band structure of the system

  20. Raman scattering study of filled skutterudite compounds

    International Nuclear Information System (INIS)

    Ogita, N; Kojima, R; Hasegawa, T; Takasu, Y; Udagawa, M; Kondo, T; Takeda, N; Ikeno, T; Ishikawa, K; Sugawara, H; Kikuchi, D; Sato, H; Sekine, C; Shirotani, I

    2007-01-01

    Raman scattering of skutterudite compounds RT 4 X 12 (R=La, Ce, Pr, Nd, Sm and Yb, T=Fe, Ru and Os, X=P and Sb) have been measured. All first-order Raman active phonons are observed and are assigned as the pnicogen vibrations. At the low energy region, the second-order phonons, due to the vibration of the rare earth ions with a flat phonon dispersion, are observed in the spectra of RRu 4 P 12 (R=La and Sm) and ROs 4 Sb 12 (R=La, Ce, Pr, Nd, and Sm). The appearance of the second-order phonons in the spectra is caused by an anharmonic vibrations of rare earth ions in large cage space and a large density of state due to the flat phonon dispersion. However, in spite of the similar cage space, the 2nd-order phonons are hardly observed for RFe 4 Sb 12 and RRu 4 Sb 12 . Thus, these results suggest that the dynamics of the rare earth ion is closely related to not only the cage size but also the electronic state due to the transition metals. Raman spectra of PrRu 4 P 12 show the drastic spectral change due to the metal-insulator transition. The phonon spectra and crystal field excitations due to the structural change have been assigned above and below the transition temperature

  1. Polarized Raman scattering of single ZnO nanorod

    International Nuclear Information System (INIS)

    Yu, J. L.; Lai, Y. F.; Wang, Y. Z.; Cheng, S. Y.; Chen, Y. H.

    2014-01-01

    Polarized Raman scattering measurement on single wurtzite c-plane (001) ZnO nanorod grown by hydrothermal method has been performed at room temperature. The polarization dependence of the intensity of the Raman scattering for the phonon modes A 1 (TO), E 1 (TO), and E 2 high in the ZnO nanorod are obtained. The deviations of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules are observed, which can be attributed to the structure defects in the ZnO nanorod as confirmed by the comparison of the transmission electron microscopy, photoluminescence spectra as well as the polarization dependent Raman signal of the annealed and unannealed ZnO nanorod. The Raman tensor elements of A 1 (TO) and E 1 (TO) phonon modes normalized to that of the E 2 high phonon mode are |a/d|=0.32±0.01, |b/d|=0.49±0.02, and |c/d|=0.23±0.01 for the unannealed ZnO nanorod, and |a/d|=0.33±0.01, |b/d|=0.45±0.01, and |c/d|=0.20±0.01 for the annealed ZnO nanorod, which shows strong anisotropy compared to that of bulk ZnO epilayer

  2. Frequency shifts in stimulated Raman scattering

    International Nuclear Information System (INIS)

    Zinth, W.; Kaiser, W.

    1980-01-01

    The nonresonant contributions to the nonlinear susceptibility chisup(()3) produce a frequency chirp during stimulated Raman scattering. In the case of transient stimulated Raman scattering, the spectrum of the generated Stokes pulse is found at higher frequencies than expected from spontaneous Raman data. The frequency difference can be calculated from the theory of stimulated Raman scattering. (orig.)

  3. Temperature dependence of Raman scattering by optical phonons in ZnTe

    International Nuclear Information System (INIS)

    Simmonds, P.E.; Martin, A.D.

    1987-01-01

    Measurements of the temperature dependence of Raman scattering by optical phonons between temperatures 5 K and 293 K in the II-VI semiconductor ZnTe are reported. Typical Raman spectra for ZnTe at different temperatures are shown and values of the measured LO and TO phonon Raman shifts and linewidths are given for T = 5, 77, and 293 K. The measured linewidth of the LO Raman line as a function of temperature is plotted and compared with model predictions based on various three- and four-phonon processes

  4. High resolution resonant Raman scattering in InP and GaAs

    International Nuclear Information System (INIS)

    Kernohan, E.T.M.

    1996-04-01

    Previous studies of III-V semiconductors using resonant Raman scattering have concentrated on measuring the variations in scattering intensity under different excitation conditions. The shape of the Raman line also contains important information, but this has usually been lost because the low signal strengths mean that resolution has been sacrificed for sensitivity. It might therefore be expected that further insights into the processes involved in Raman scattering could be obtained by using high resolution methods. In this thesis I have measured single- and multiple- phonon scattering from bulk GaAs and InP with a spectral resolution better than the intrinsic widths of the Raman lines. For scattering in the region of one longitudinal optic (LO) phonon energy, it is found that in InP the scattering in the allowed and forbidden configurations occur at different Raman shifts, above and below the zone-centre phonon energy respectively. These shifts are used to determine the scattering processes involved, and how they differ between InP and GaAs. The lineshapes obtained in multiple-phonon scattering are found to depend strongly on the excitation energy used, providing evidence for the presence of intermediate resonances. The measured spectra are used to provide information about the phonon dispersion of InP, whose dispersion it is difficult to measure in any other way, and the first evidence is found for an upward dispersion of the LO mode. Raman lineshapes are measured for InP in a magnetic field. The field alters the electronic bandstructure, leading to a series of strong resonances in the Raman efficiency due to interband magneto-optical transitions between Landau levels. This allows multiphonon processes up to sixth-order to be investigated. (author)

  5. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    International Nuclear Information System (INIS)

    Kirillov, D.; Bozovic, I.; Geballe, T.H.; Kapitulnik, A.; Mitzi, D.B.

    1988-01-01

    Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 was found

  6. Raman scattering spectra of superconducting Bi2Sr2CaCu2O8 single crystals

    Science.gov (United States)

    Kirillov, D.; Bozovic, I.; Geballe, T. H.; Kapitulnik, A.; Mitzi, D. B.

    1988-12-01

    Raman spectra of Bi2Sr2CaCu2O8 single crystals with superconducting phase-transition temperature of 90 K have been studied. The spectra contained phonon lines and electronic continuum. Phonon energies and polarization selection rules were measured. A gap in the electronic continuum spectrum was observed in a superconducting state. Noticeable similarity between Raman spectra of Bi2Sr2CaCu2O8 and YBa2Cu3O7 was found.

  7. Temperature dependence of low-frequency polarized Raman scattering spectra in TlInS{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Paucar, Raul; Wakita, Kazuki [Electronics and Computer Engineering, Chiba Institute of Technology, Chiba (Japan); Shim, YongGu; Mimura, Kojiro [Graduate School of Engineering, Osaka Prefecture University, Osaka (Japan); Alekperov, Oktay; Mamedov, Nazim [Institute of Physics, Azerbaijan National Academy of Sciences, Baku (Azerbaijan)

    2017-06-15

    In this work, we examined phase transitions in the layered ternary thallium chalcogenide TlInS{sub 2} by studying the temperature dependence of polarized Raman spectra with the aid of the Raman confocal microscope system. The Raman spectra were measured over the temperature range of 77-320 K (which includes the range of successive phase transitions) in the low-frequency region of 35-180 cm{sup -1}. The optical phonons that showed strong temperature dependence were identified as interlayer vibrations related to phase transitions, while the phonons that showed weak temperature dependence were identified as intralayer vibrations. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. X-ray resonant Raman scattering cross sections of Mn, Fe, Cu and Zn

    International Nuclear Information System (INIS)

    Sanchez, Hector Jorge; Valentinuzzi, MarIa Cecilia; Perez, Carlos

    2006-01-01

    X-ray fluorescence spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower and close to an absorption edge, scattering peaks appear due to an inelastic process known as resonant Raman scattering. It constitutes an important contribution to the background of the fluorescent line. The resonant Raman scattering must be taken into account in the determination of low concentration contaminants, especially when the elements have proximate atomic numbers. The values of the mass attenuation coefficients experimentally obtained when materials are analysed with monochromatic x-ray beams under resonant conditions differ from the theoretical values (between 5% and 10%). This difference is due, in part, to the resonant Raman scattering. Monochromatic synchrotron radiation was used to study the Raman effect on pure samples of Mn, Fe, Cu and Zn. Energy scans were carried out in different ranges of energy near the absorption edge of the target element. As the Raman peak has a non-symmetric shape, theoretical models for the differential cross section, convoluted with the instrument function, were used to determine the RRS cross section as a function of the incident energy

  9. Raman Spectra from Pesticides on the Surface of Fruits

    International Nuclear Information System (INIS)

    Zhang, P X; Zhou Xiaofang; Cheng, Andrew Y S; Fang Yan

    2006-01-01

    Raman spectra of several vegetables and fruits were studied by micro-Raman spectrometer (514.5 nm) and Near-infrared Fourier Transform Raman spectrometer (FTRaman). It is shown that at 514.5 nm excitation, most of the spectra are from that of carotene with some very strong fluorescence in some cases. While at 1064 nm wavelength excitation, the spectra from the different samples demonstrate different characteristic Raman spectra without fluorescence. We discuss the spectroscopic difference by the two excitation wavelengths, and the application of Raman spectra for detection of pesticides left on the surface of vegetables and fruits. Raman spectra of fruits and pesticides were successfully recorded, and using the FT-Raman spectra the pesticides left on the surface of the fruits can be detected conveniently

  10. Application of Raman spectroscopy and surface-enhanced Raman scattering to the analysis of synthetic dyes found in ballpoint pen inks.

    Science.gov (United States)

    Geiman, Irina; Leona, Marco; Lombardi, John R

    2009-07-01

    The applicability of Raman spectroscopy and surface-enhanced Raman scattering (SERS) to the analysis of synthetic dyes commonly found in ballpoint inks was investigated in a comparative study. Spectra of 10 dyes were obtained using a dispersive system (633 nm, 785 nm lasers) and a Fourier transform system (1064 nm laser) under different analytical conditions (e.g., powdered pigments, solutions, thin layer chromatography [TLC] spots). While high fluorescence background and poor spectral quality often characterized the normal Raman spectra of the dyes studied, SERS was found to be generally helpful. Additionally, dye standards and a single ballpoint ink were developed on a TLC plate following a typical ink analysis procedure. SERS spectra were successfully collected directly from the TLC plate, thus demonstrating a possible forensic application for the technique.

  11. Development of a Raman spectrometer to study surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Biswas, Nandita; Chadha, Ridhima; Kapoor, Sudhir; Sarkar, Sisir K.; Mukherjee, Tulsi

    2011-02-01

    Raman spectroscopy is an important tool, which provides enormous information on the vibrational and structural details of materials. This understanding is not only interesting due to its fundamental importance, but also of considerable importance in optoelectronics and device applications of these materials in nanotechnology. In this report, we begin with a brief introduction on the Raman effect and various Raman scattering techniques, followed by a detailed discussion on the development of an instrument with home-built collection optics attachment. This Raman system consists of a pulsed laser excitation source, a sample compartment, collection optics to collect the scattered light, a notch filter to reject the intense laser light, a monochromator to disperse the scattered light and a detector to detect the Raman signal. After calibrating the Raman spectrometer with standard solvents, we present our results on Surface-Enhanced Raman Scattering (SERS) investigations on three different kinds of chemical systems. (author)

  12. Raman scattering in a nearly resonant density ripple

    International Nuclear Information System (INIS)

    Barr, H.C.; Chen, F.F.

    1987-01-01

    Stimulated Raman scattering of light waves by an underdense plasma is affected by the presence of a density ripple caused by a simultaneously occurring stimulated Brillouin instability. The problem is treated kinetically for the particularly interesting case where the ripple has nearly the same wavelength as the plasma wave. The ripple is found to reduce the growth rate of the usual Raman instability but allows other decay modes to occur. Numerical results for the frequencies, growth rates, and k spectra of these modes are obtained. A physical explanation is given for a baffling result of the calculation. The physical picture is also of interest to particle acceleration by plasma waves

  13. Raman scattering characterization of space solar cell structures

    Science.gov (United States)

    Mintairov, Alexander M.; Khvostikov, V. P.; Paleeva, E. V.; Sorokina, S. V.

    1995-01-01

    A contactless method for the determination of the free-carrier density and the composition distribution across the thickness of 3-5 multi-layer solar cell structures, using the Raman scattering method, is developed. The method includes a step analysis of Raman spectra from optical phonons and phonon-plasmon modes of different layers. The method provides simultaneous measurements of the element composition and the thickness of the structure's layers together with the free-carrier density. The results of measurements of the free-carrier density composition distributions of the liquid phase epitaxy grown AlGaAs/GaAs and GaSb solar cell structures are presented and discussed.

  14. An Investigation on Micro-Raman Spectra and Wavelet Data Analysis for Pemphigus Vulgaris Follow-up Monitoring.

    Science.gov (United States)

    Camerlingo, Carlo; Zenone, Flora; Perna, Giuseppe; Capozzi, Vito; Cirillo, Nicola; Gaeta, Giovanni Maria; Lepore, Maria

    2008-06-01

    A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra of blood serum samples from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. Spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded Raman spectra in order to overcome problems related to low-level signals and the presence of noise and background components due to light scattering and fluorescence. This numerical data treatment can automatically extract quantitative information from the Raman spectra and makes more reliable the data comparison. Even if an exhaustive investigation has not been done in this work, the feasibility of the follow-up monitoring of pemphigus vulgaris pathology has been clearly proved with useful implications for the clinical applications.

  15. An Investigation on Micro-Raman Spectra and Wavelet Data Analysis for Pemphigus Vulgaris Follow-up Monitoring.

    Directory of Open Access Journals (Sweden)

    Maria Lepore

    2008-06-01

    Full Text Available A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra of blood serum samples from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. Spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded Raman spectra in order to overcome problems related to low-level signals and the presence of noise and background components due to light scattering and fluorescence. This numerical data treatment can automatically extract quantitative information from the Raman spectra and makes more reliable the data comparison. Even if an exhaustive investigation has not been done in this work, the feasibility of the follow-up monitoring of pemphigus vulgaris pathology has been clearly proved with useful implications for the clinical applications.

  16. How Does the Shape of the Stellar Spectrum Affect the Raman Scattering Features in the Albedo of Exoplanets?

    Energy Technology Data Exchange (ETDEWEB)

    Oklopčić, Antonija [California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Hirata, Christopher M. [Center for Cosmology and Astroparticle Physics, Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210 (United States); Heng, Kevin, E-mail: oklopcic@astro.caltech.edu [Center for Space and Habitability, University of Bern, Sidlerstrasse 5, CH-3012, Bern (Switzerland)

    2017-09-10

    The diagnostic potential of the spectral signatures of Raman scattering, imprinted in planetary albedo spectra at short optical wavelengths, has been demonstrated in research on planets in the solar system, and has recently been proposed as a probe of exoplanet atmospheres, complementary to albedo studies at longer wavelengths. Spectral features caused by Raman scattering offer insight into the properties of planetary atmospheres, such as the atmospheric depth, composition, and temperature, as well as the possibility of detecting and spectroscopically identifying spectrally inactive species, such as H{sub 2} and N{sub 2}, in the visible wavelength range. Raman albedo features, however, depend on both the properties of the atmosphere and the shape of the incident stellar spectrum. Identical planetary atmospheres can produce very different albedo spectra depending on the spectral properties of the host star. Here we present a set of geometric albedo spectra calculated for atmospheres with H{sub 2}/He, N{sub 2}, and CO{sub 2} composition, irradiated by different stellar types ranging from late A to late K stars. Prominent albedo features caused by Raman scattering appear at different wavelengths for different types of host stars. We investigate how absorption due to the alkali elements sodium and potassium may affect the intensity of Raman features, and we discuss the preferred strategies for detecting Raman features in future observations.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2013-01-01

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

  18. Wavelet data analysis of micro-Raman spectra for follow-up monitoring in oral pathologies

    Science.gov (United States)

    Camerlingo, C.; Zenone, F.; Perna, G.; Capozzi, V.; Cirillo, N.; Gaeta, G. M.; Lepore, M.

    2008-02-01

    A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra from human biological samples. In particular, measurements have been performed on some samples of oral tissue and blood serum from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. The disease is characterized histologically by intradermal blisters and immunopathologically by the finding of tissue bound and circulating immunoglobulin G (IgG) antibody directed against the cell surface of keratinocytes. More than 150 spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has been applied to the recorded Raman spectra in order to overcome related to low-level signals and the presence of noise and background components due to light scattering and fluorescence. The results indicate that appropriate data processing can contribute to enlarge the medical applications of micro-Raman spectroscopy.

  19. One phonon resonant Raman scattering in semiconductor quantum wires: Magnetic field effect

    Energy Technology Data Exchange (ETDEWEB)

    Betancourt-Riera, Re., E-mail: rbriera@posgrado.cifus.uson.mx [Instituto Tecnologico de Hermosillo, Avenida Tecnologico S/N, Colonia Sahuaro, C.P. 83170, Hermosillo, Sonor, (Mexico); Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, C.P. 83190, Hermosillo, Sonora (Mexico); Betancourt-Riera, Ri. [Instituto Tecnologico de Hermosillo, Avenida Tecnologico S/N, Colonia Sahuaro, C.P. 83170, Hermosillo, Sonora (Mexico); Nieto Jalil, J.M. [Tecnologico de Monterrey-Campus Sonora Norte, Bulevar Enrique Mazon Lopez No. 965, C.P. 83000, Hermosillo, Sonora (Mexico); Riera, R. [Departamento de Investigacion en Fisica, Universidad de Sonora, Apartado Postal 5-088, C.P. 83190, Hermosillo, Sonora (Mexico)

    2013-02-01

    We have developed a theory of one phonon resonant Raman scattering in a semiconductor quantum wire of cylindrical geometry in the presence of an external magnetic field distribution, parallel to the cylinder axis. The effect of the magnetic field in the electron and hole states, and in the Raman scattering efficiency, is determinate. We consider the electron-phonon interaction using a Froehlich-type Hamiltonian, deduced for the case of complete confinement phonon modes by Comas and his collaborators. We also assume T=0 K, a single parabolic conduction and valence bands. The spectra are discussed for different magnetic field values and the selection rules for the processes are also studied.

  20. Two Magnon Raman Scattering as Indicator for Superconducting to Antiferromagnetic Phase Transition Upon Hydrogenation of YBCO

    International Nuclear Information System (INIS)

    Biton, Y.; Shuker, R.

    1999-01-01

    Raman spectra of Hydrogenated YBa 2 Cu 3 O 7-x + H y , where y = 0.45 and 0.19 is the number of Hydrogen atoms per units cell. The spectra exhibit important changes in the electronic scattering. Upon progressive doping with Hydrogen two magnon scattering features emerge. This coincides with the transition of YBa 2 Cu 3 O 7x +H y from superconducting to antiferromagnetic phase. Exchange energy values were obtained from two magnon Raman scattering of the y = 0.45 material. It has been found that for y= 0.19 the sample has not lost its superconductivity, and indeed two-magnon scattering has not been observed. However, the situation changed substantially when the doping of the Hydrogen atoms was 0.45. The two-magnon scattering has been observed at different temperatures down to 20K. The two-magnon energy density exhibits two peak values around 2100cm -1 and 3000cm -1

  1. Evaluation of Shifted Excitation Raman Difference Spectroscopy and Comparison to Computational Background Correction Methods Applied to Biochemical Raman Spectra.

    Science.gov (United States)

    Cordero, Eliana; Korinth, Florian; Stiebing, Clara; Krafft, Christoph; Schie, Iwan W; Popp, Jürgen

    2017-07-27

    Raman spectroscopy provides label-free biochemical information from tissue samples without complicated sample preparation. The clinical capability of Raman spectroscopy has been demonstrated in a wide range of in vitro and in vivo applications. However, a challenge for in vivo applications is the simultaneous excitation of auto-fluorescence in the majority of tissues of interest, such as liver, bladder, brain, and others. Raman bands are then superimposed on a fluorescence background, which can be several orders of magnitude larger than the Raman signal. To eliminate the disturbing fluorescence background, several approaches are available. Among instrumentational methods shifted excitation Raman difference spectroscopy (SERDS) has been widely applied and studied. Similarly, computational techniques, for instance extended multiplicative scatter correction (EMSC), have also been employed to remove undesired background contributions. Here, we present a theoretical and experimental evaluation and comparison of fluorescence background removal approaches for Raman spectra based on SERDS and EMSC.

  2. Breast cancer study in rats by using Raman scattering

    International Nuclear Information System (INIS)

    Martinez E, J. C.; Cordova F, T.; Roca Ch, J. M.; Hernandez R, A.

    2015-10-01

    Full text: The use of Raman scattering to differentiate the biochemistry and hence distinguish between normal and abnormal samples of breast cancer with induced stress was investigated. Twelve different rat serum samples (5 control samples and 7 breast cancer samples) were measured. 25 spectra per sample were acquired in a region of 50 X 50 microns. Three hundred spectra were recorded and the spectral diagnostic models were constructed by using multivariate statistical analysis on the spectral matrix to carry out the discrimination between the control samples and cancers samples with induced stress. The spectral recording was performed with Raman microscopy system Thermo Scientific XRD in the range from 200 to 2000 cm -1 with a laser source of 780 nm, 24 m W of power and 50 s and exposure time were used for each spectrum. It is shown that the serum samples from rats with breast cancer and the control group can be discriminate when the multivariate analysis methods are applied to their Raman data set. The ratios were significant and correspond to proteins and phospholipids. The preliminary results suggest that the Raman spectroscopy could be an alternative technique to study the breast cancer in humans in a near future. (Author)

  3. Breast cancer study in rats by using Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Martinez E, J. C. [IPN, Unidad Profesional Interdisciplinaria de Ingenieria, Campus Guanajuato, Av. Mineral de Valenciana 200, Col. Fracc. Industrial Puerto Interior, 36275 Silao, Guanajuato (Mexico); Cordova F, T.; Roca Ch, J. M.; Hernandez R, A., E-mail: jcmartineze@ipn.mx [Universidad de Guanajuato, Division de Ciencias e Ingenierias, Departamento de Ingenieria Fisica, Loma del Bosque 103, Col. Lomas del Campestre, 37150 Leon, Guanajuato (Mexico)

    2015-10-15

    Full text: The use of Raman scattering to differentiate the biochemistry and hence distinguish between normal and abnormal samples of breast cancer with induced stress was investigated. Twelve different rat serum samples (5 control samples and 7 breast cancer samples) were measured. 25 spectra per sample were acquired in a region of 50 X 50 microns. Three hundred spectra were recorded and the spectral diagnostic models were constructed by using multivariate statistical analysis on the spectral matrix to carry out the discrimination between the control samples and cancers samples with induced stress. The spectral recording was performed with Raman microscopy system Thermo Scientific XRD in the range from 200 to 2000 cm{sup -1} with a laser source of 780 nm, 24 m W of power and 50 s and exposure time were used for each spectrum. It is shown that the serum samples from rats with breast cancer and the control group can be discriminate when the multivariate analysis methods are applied to their Raman data set. The ratios were significant and correspond to proteins and phospholipids. The preliminary results suggest that the Raman spectroscopy could be an alternative technique to study the breast cancer in humans in a near future. (Author)

  4. Detection of aniline oligomers on polyaniline-gold interface using resonance Raman scattering.

    Science.gov (United States)

    Trchová, Miroslava; Morávková, Zuzana; Dybal, Jiří; Stejskal, Jaroslav

    2014-01-22

    In situ deposited conducting polyaniline films prepared by the oxidation of aniline with ammonium peroxydisulfate in aqueous media of various acidities on gold and silicon supports were characterized by Raman spectroscopy. Enhanced Raman bands were found in the spectra of polyaniline films produced in the solutions of weak acids or in water on gold surface. These bands were weak for the films prepared in solutions of a strong acid on a gold support. The same bands are present in the Raman spectra of the reaction intermediates deposited during aniline oxidation in water or aqueous solutions of weak or strong acids on silicon removed from the reaction mixture at the beginning of the reaction. Such films are formed by aniline oligomers adsorbed on the surface. They were detected on the polyaniline-gold interface using resonance Raman scattering on the final films deposited on gold. The surface resonance Raman spectroscopy of the monolayer of oligomers found in the bulk polyaniline film makes this method advantageous in surface science, with many applications in electrochemistry, catalysis, and biophysical, polymer, or analytical chemistry.

  5. Raman scattering intensities in BaTiO3 and PbTiO3 prototypical ferroelectrics from density functional theory

    International Nuclear Information System (INIS)

    Hermet, P; Veithen, M; Ghosez, Ph

    2009-01-01

    Nonlinear optical susceptibilities and Raman scattering spectra of the ferroelectric phases of BaTiO 3 and PbTiO 3 are computed using a first-principles approach based on density functional theory and taking advantage of a recent implementation based on the nonlinear response formalism and the 2n+1 theorem. These two prototypical ferroelectric compounds were chosen to demonstrate the accuracy of the Raman calculation based both on their complexity and their technological importance. The computation of the Raman scattering intensities has been performed not only for the transverse optical modes, but also for the longitudinal optical ones. The agreement between the measured and computed Raman spectra of these prototypical ferroelectrics is remarkable for both the frequency position and the intensity of Raman lines. This agreement presently demonstrates the state-of-the-art in the computation of Raman responses on one of the most complex systems, ferroelectrics, and constitutes a step forward in the reliable prediction of their electro-optical responses.

  6. Raman spectra of filled carbon nanotubes

    International Nuclear Information System (INIS)

    Bose, S.M.; Behera, S.N.; Sarangi, S.N.; Entel, P.

    2004-01-01

    The Raman spectra of a metallic carbon nanotube filled with atoms or molecules have been investigated theoretically. It is found that there will be a three way splitting of the main Raman lines due to the interaction of the nanotube phonon with the collective excitations (plasmons) of the conduction electrons of the nanotube as well as its coupling with the phonon of the filling material. The positions and relative strengths of these Raman peaks depend on the strength of the electron-phonon interaction, phonon frequency of the filling atom and the strength of interaction of the nanotube phonon and the phonon of the filling atoms. Careful experimental studies of the Raman spectra of filled nanotubes should show these three peaks. It is also shown that in a semiconducting nanotube the Raman line will split into two and should be observed experimentally

  7. Raman Optical Activity and Raman Spectra of Amphetamine Species

    DEFF Research Database (Denmark)

    Berg, Rolf W.; Shim, Irene; White, Peter Cyril

    2012-01-01

    Theoretical calculations and preliminary measurements of vibrational Raman optical activity (ROA) spectra of different species of amphetamine (amphetamine and amphetamine-H+) are reported for the first time. The quantum chemical calculations were carried out as hybrid ab initio DFT-molecular orbi......Theoretical calculations and preliminary measurements of vibrational Raman optical activity (ROA) spectra of different species of amphetamine (amphetamine and amphetamine-H+) are reported for the first time. The quantum chemical calculations were carried out as hybrid ab initio DFT...... are employed for identification purposes. The DFT calculations show that the most stable conformations are those allowing for close contact between the aromatic ring and the amine hydrogen atoms. The internal rotational barrier within the same amphetamine enanti- omer has a considerable influence on the Raman...

  8. Evidence for anisotropic excitonlike enhancement of the Raman scattering from La2CuO4

    International Nuclear Information System (INIS)

    Weber, W.H.; Peters, C.R.; Wanklyn, B.M.; Chen, C.; Watts, B.E.

    1988-01-01

    Polarized Raman studies on oriented single crystals of La 2 CuO 4 yield α/sub z//sub z/ spectra with narrow lines at 429 and 228 cm/sup -1/ that are identified as the two A 1 /sub g/ modes expected for the tetragonal K 2 NiF 4 structure; α/sub x//sub z/ spectra with one line at 228 cm/sup -1/ that has E/sub g/ symmetry; and α/sub x//sub x/ spectra with numerous peaks that are due to normally forbidden phonon excitations. The α/sub x//sub x/ spectra also show strong second-order features, suggesting a highly anisotropic, excitonlike enhancement of the Raman scattering

  9. Schwinger–Keldysh canonical formalism for electronic Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Su, Yuehua, E-mail: suyh@ytu.edu.cn

    2016-03-01

    Inelastic low-energy Raman and high-energy X-ray scatterings have made great progress in instrumentation to investigate the strong electronic correlations in matter. However, theoretical study of the relevant scattering spectrum is still a challenge. In this paper, we present a Schwinger–Keldysh canonical perturbation formalism for the electronic Raman scattering, where all the resonant, non-resonant and mixed responses are considered uniformly. We show how to use this formalism to evaluate the cross section of the electronic Raman scattering off an one-band superconductor. All the two-photon scattering processes from electrons, the non-resonant charge density response, the elastic Rayleigh scattering, the fluorescence, the intrinsic energy-shift Raman scattering and the mixed response, are included. In the mean-field superconducting state, Cooper pairs contribute only to the non-resonant response. All the other responses are dominated by the single-particle excitations and are strongly suppressed due to the opening of the superconducting gap. Our formalism for the electronic Raman scattering can be easily extended to study the high-energy resonant inelastic X-ray scattering.

  10. Raman scattering temperature measurements for water vapor in nonequilibrium dispersed two-phase flow

    International Nuclear Information System (INIS)

    Anastasia, C.M.; Neti, S.; Smith, W.R.; Chen, J.C.

    1982-09-01

    The objective of this investigation was to determine the feasibility of using Raman scattering as a nonintrusive technique to measure vapor temperatures in dispersed two-phase flow. The Raman system developed for this investigation is described, including alignment of optics and optimization of the photodetector for photon pulse counting. Experimentally obtained Raman spectra are presented for the following single- and two-phase samples: liquid water, atmospheric nitrogen, superheated steam, nitrogen and water droplets in a high void fraction air/water mist, and superheated water vapor in nonequilibrium dispersed flow

  11. Electronic Raman spectra in iron-based superconductors with two-orbital model

    International Nuclear Information System (INIS)

    Lu Hongyan; Wang Da; Chen San; Wang Wei; Gong Pifeng

    2011-01-01

    Electronic Raman spectra were calculated in orbital space in a microscopic theory. Both Raman spectra and spectra weight were presented. Raman spectra for the gap symmetries are different from each other. The results can help decide the gap symmetry by comparing with experiments. Electronic Raman spectra in iron-based superconductors with two-orbital model is discussed. In the orbital space, some possible pairing symmetries of the gap are selected. To further discriminate them, electronic Raman spectra and spectra weight at Fermi surface (FS) which helps understand the Raman spectra are calculated in each case. From the low energy threshold, the number of Raman peaks, and the low frequency power law behavior, we can judge whether it is full gap or nodal gap, and even one gap or multi-gaps. The results provide useful predictions for comparison with experiments.

  12. Raman scattering in the atmospheres of the major planets

    International Nuclear Information System (INIS)

    Cochran, W.D.; Trafton, L.M.

    1978-01-01

    A method is developed for calculating the rate at which photons are Raman scattered as a function of frequency and depth in an inhomogeneous anisotropically scattering atmosphere. This method is used to determine the effects of Raman scattering by H 2 in the atmospheres of the major planets. Raman scattering causes an insufficient decrease in the blue and ultraviolet to explain the albedos of all of the planets; an additional source of extinction is necessary in this spectral region. Approximately 0.5-2.0% of the blue continuum photons have undergone Raman scattering in the shallow atmospheres of Jupiter and Saturn, while in the deep atmospheres of Uranus and Neptune Raman scattering accounts for abount 10-15% of the blue continuum intensity. The filling in of the cores of solar lines and the production of Raman-shifted ghosts of the Fraunhofer spectrum will be detectable effects in all of the major planets. Raman scattering has a significant influence on the formation and profiles of the strong red and near-infrared CH 4 bands on Uranus and Neptune. The residual intensity in the cores of these bands may be fully explained as a result of Raman scattering by H 2 . This scattering of photons into the cores of saturated absorption bands will cause an underestimate of the abundance of the absorber unless the effects of Raman scattering by H 2 in an inhomogeneous atmosphere are properly included in the analysis

  13. Raman vibrational spectra of thymol blue dyed polyvinyl alcohol (PVA) film dosimeters

    International Nuclear Information System (INIS)

    Lepit, A.; Saion, E.B.; Susilawati; Doyan, A.; Wan Yusoff, W.M.D.

    2002-01-01

    Radiation-sensitive dyed polyvinyl alcohol (PVA) film indicators containing chloral hydrate and acid-sensitive thymol blue dye have been studied for routine food irradiation dosimeters. The free standing dyed film dosimeters of different chloral hydrate concentrations (0.1, 0.5, 1.0, 2.0 and 2.5 g) were irradiated with the absorbed dose ranges from 1 kGy to 12 kGy using gamma rays from Co-60 teletherapy. Upon exposure the dosimeters undergo chemical change and become more acidic, resulting in colour change from yellow to red at the critical doses depending on the chloral hydrate concentrations. The radiation-induced change in colour was analysed using UV-Vis spectrometer that the absorption spectra produced two maximal of the visible bands peaking at 445 nm for low doses and 554 nm for high doses. Spectra of inelastic Raman scattering photons corresponding to Raman shift frequency of unirradiated and irradiated films were measured using a dispersive Raman spectrometer. The spectral intensity of C=C, C-0 and S-H molecular vibration peaks for their respective Raman shifts were studied which provide the dose response to the change of dye molecular structure of the dosimeters. (Author)

  14. Surface-enhanced resonance Raman scattering spectroscopy of single R6G molecules

    Institute of Scientific and Technical Information of China (English)

    Zhou Zeng-Hui; Liu Li; Wang Gui-Ying; Xu Zhi-Zhan

    2006-01-01

    Surface-enhanced resonance Raman scattering (SERRS) of Rhodamine 6G (R6G) adsorbed on colloidal silver clusters has been studied. Based on the great enhancement of the Raman signal and the quench of the fluorescence, the SERRS spectra of R6G were recorded for the samples of dye colloidal solution with different concentrations. Spectral inhomogeneity behaviours from single molecules in the dried sample films were observed with complementary evidences, such as spectral polarization, spectral diffusion, intensity fluctuation of vibrational lines and even "breathing" of the molecules. Sequential spectra observed from a liquid sample with an average of 0.3 dye molecules in the probed volume exhibited the expected Poisson distribution for actually measuring 0, 1 or 2 molecules. Difference between the SERRS spectra of R6G excited by linearly and circularly polarized light were experimentally measured.

  15. Surface-enhanced Raman scattering spectra revealing the inter-cultivar differences for Chinese ornamental Flos Chrysanthemum: a new promising method for plant taxonomy

    Directory of Open Access Journals (Sweden)

    Heng Zhang

    2017-10-01

    Full Text Available Abstract Background Flos Chrysanthemi, as a part of Chinese culture for a long history, is valuable for not only environmental decoration but also the medicine and food additive. Due to their voluminously various breeds and extensive distributions worldwide, it is burdensome to make recognition and classification among numerous cultivars with conventional methods which still rest on the level of morphologic observation and description. As a fingerprint spectrum for parsing molecular information, surface-enhanced Raman scattering (SERS could be a suitable candidate technique to characterize and distinguish the inter-cultivar differences at molecular level. Results SERS spectra were used to analyze the inter-cultivar differences among 26 cultivars of Chinese ornamental Flos Chrysanthemum. The characteristic peaks distribution patterns were abstracted from SERS spectra and varied from cultivars to cultivars. For the bands distributed in the pattern map, the similarities in general showed their commonality while in the finer scales, the deviations and especially the particular bands owned by few cultivars revealed their individualities. Since the Raman peaks could characterize specific chemical components, those diversity of patterns could indicate the inter-cultivar differences at the chemical level in fact. Conclusion In this paper, SERS technique is feasible for distinguishing the inter-cultivar differences among Flos Chrysanthemum. The Raman spectral library was built with SERS characteristic peak distribution patterns. A new method was proposed for Flos Chrysanthemum recognition and taxonomy.

  16. Resonance Raman scattering of β-carotene solution excited by visible laser beams into second singlet state.

    Science.gov (United States)

    Lu, Luyao; Shi, Lingyan; Secor, Jeff; Alfano, Robert

    2018-02-01

    This study aimed to use self-absorption correction to determine the Raman enhancement of β-carotene. The Raman spectra of β-carotene solutions were measured using 488nm, 514nm, 532nm and 633nm laser beams, which exhibited significant resonance Raman (RR) enhancement when the laser energy approaches the electronic transition energy from S 0 to S 2 state. The Raman intensity and the actual resonance Raman gain without self-absorption from S 2 state by β-carotene were also obtained to evaluate the effect of self-absorption on RR scattering. Moreover, we observed the Raman intensity strength followed the absorption spectra. Our study found that, although 488nm and 514nm pumps seemed better for stronger RR enhancement, 532nm would be the optimum Raman pump laser with moderate RR enhancement due to reduced fluorescence and self-absorption. The 532nm excitation will be helpful for applying resonance Raman spectroscopy to investigate biological molecules in tissues. Copyright © 2017 Elsevier B.V. All rights reserved.

  17. Measurement and Simulation of Spontaneous Raman Scattering Spectra in High-Pressure, Fuel-Rich H2-Air Flames

    Science.gov (United States)

    Kojima, Jun; Nguyen, Quang-Viet

    2003-01-01

    Rotational vibrational spontaneous Raman spectra (SRS) of H2, N2, and H2O have been measured in H2-air flames at pressures up to 30 atm as a first stem towards establishing a comprehensive Raman spectral database for temperatures and species in high-pressure combustion. A newly developed high-pressure burner facility provides steady, reproducible flames with a high degree of flow precision. We have obtained an initial set of measurements that indicate the spectra are of sufficient quality in terms of spectral resolution, wavelength coverage, and signal-to-noise ratio for use in future reference standards. The fully resolved Stokes and anti-Stokes shifted SRS spectra were collected in the visible wavelength range (400-700 nm) using pulse-stretched 532 nm excitation and a non-intensified CCD spectrograph with a high-speed shutter. Reasonable temperatures were determined via the intensity distribution of rotational H2 lines at stoichiometry and fuel-rich conditions. Theoretical Raman spectra of H2 were computed using a semi-classical harmonic-oscillator model with recent pressure broadening data and were compared with experimental results. The data and simulation indicated that high-J rotational lines of H2 might interfere with the N2 vibrational Q-branch lines, and this could lead to errors in N2-Raman thermometry based on the line-fitting method. From a comparison of N2 Q-branch spectra in lean H2 low-pressure (1.2 atm) and high-pressure (30 atm) flames, we found no significant line-narrowing or -broadening effects at the current spectrometer resolution of 0.04 nm.

  18. Analysis of polymer surfaces and thin-film coatings with Raman and surface enhanced Raman scattering

    International Nuclear Information System (INIS)

    McAnally, Gerard David

    2001-01-01

    This thesis investigates the potential of surface-enhanced Raman scattering (SERS) for the analysis and characterisation of polymer surfaces. The Raman and SERS spectra from a PET film are presented. The SERS spectra from the related polyester PBT and from the monomer DMT are identical to PET, showing that only the aromatic signals are enhanced. Evidence from other compounds is presented to show that loss of the carbonyl stretch (1725 cm -1 ) from the spectra is due to a chemical interaction between the silver and surface carbonyl groups. The interaction of other polymer functional groups with silver is discussed. A comparison of Raman and SERS spectra collected from three faces of a single crystal shows the SERS spectra are depolarised. AFM images of the silver films used to obtain SERS are presented. They consist of regular islands of silver, fused together to form a complete film. The stability and reproducibility and of these surfaces is assessed. Band assignments for the SERS spectrum of PET are presented. A new band in the spectrum (1131 cm -1 ) is assigned to a complex vibration using a density functional calculation. Depth profiling through a polymer film on to the silver layer showed the SERS signals arise from the silver surface only. The profiles show the effects of refraction on the beam, and the adverse affect on the depth resolution. Silver films were used to obtain SERS spectra from a 40 nm thin-film coating on PET, without interference from the PET layer. The use of an azo dye probe as a marker to detect the coating is described. Finally, a novel method for the synthesis of a SERS-active vinyl-benzotriazole monomer is reported. The monomer was incorporated into a thin-film coating and the SERS spectrum obtained from the polymer. (author)

  19. Raman spectra of lignin model compounds

    Science.gov (United States)

    Umesh P. Agarwal; Richard S. Reiner; Ashok K. Pandey; Sally A. Ralph; Kolby C. Hirth; Rajai H. Atalla

    2005-01-01

    To fully exploit the value of Raman spectroscopy for analyzing lignins and lignin containing materials, a detailed understanding of lignins’ Raman spectra needs to be achieved. Although advances made thus far have led to significant growth in application of Raman techniques, further developments are needed to improve upon the existing knowledge. Considering that lignin...

  20. Transformation of photoluminescence and Raman scattering spectra of Si-rich Al{sub 2}O{sub 3} films at thermal annealing

    Energy Technology Data Exchange (ETDEWEB)

    Vergara Hernandez, E. [UPIITA-Instituto Politecnico Nacional, Mexico DF 07320 (Mexico); Torchynska, T.V., E-mail: ttorch@esfm.ipn.mx [ESFM-Instituto Politecnico Nacional, Mexico DF 07320 (Mexico); Jedrzejewski, J.; Balberg, I. [Racah Institute of Physics, Hebrew University, 91904 Jerusalem (Israel)

    2014-11-15

    The effect of thermal annealing on optical properties of Al{sub 2}O{sub 3} films with the different Si contents was investigated using the photoluminescence and Raman scattering methods. Si-rich Al{sub 2}O{sub 3} films were prepared by RF magnetron co-sputtering of Si and Al{sub 2}O{sub 3} targets on long quartz glass substrates. Photoluminescence (PL) spectra of as grown Si-rich Al{sub 2}O{sub 3} films are characterized by four PL bands with the peak positions at 2.90, 2.70, 2.30 and 1.45 eV. The small intensity Raman peaks related to the scattering in the amorphous Si phase has been detected in as grown films as well. Thermal annealing at 1150 °C for 90 min stimulates the formation of Si nanocrystals (NCs) in the film area with the Si content exceeded 50%. The Raman peak related to the scattering on optic phonons in Si NCs has been detected for this area. After thermal annealing the PL intensity of all mentioned PL bands decreases in the film area with smaller Si content (≤50%) and increases in the film area with higher Si content (≥50%). Simultaneously the new PL band with the peak position at 1.65 eV appears in the film area with higher Si content (≥50%). The new PL band (1.65 eV) is attributed to the exciton recombination inside of small size Si NCs (2.5–2.7 nm). In bigger size Si NCs (3.5–5.0 nm) the PL band at 1.65 eV has been not detected due to the impact, apparently, of elastic strain appeared at the Si/Al{sub 2}O{sub 3} interface. Temperature dependences of PL spectra for the Si-rich Al{sub 2}O{sub 3} films have been studied in the range of 10–300 K with the aim to reveal the mechanism of recombination transitions for the mentioned above PL bands 2.90, 2.70, 2.30 and 1.45 eV in as grown films. The thermal activation of PL intensity and permanent PL peak positions in the temperature range 10–300 K permit to assign these PL bands to defect related emission in Al{sub 2}O{sub 3} matrix.

  1. Raman scattering signatures of the unusual vibronic interaction of molecules in liquid helium-3

    Energy Technology Data Exchange (ETDEWEB)

    Tehver, I., E-mail: imbi.tehver@ut.ee [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Benedek, G. [Donostia International Physics Center (DIPC) and University of the Basque Country (EHU), Paseo de Lardizabal 4, 20018 Donostia/San Sebastian (Spain); Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, Via Cozzi 53, 20125 Milano (Italy); Hizhnyakov, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia)

    2015-10-16

    Highlights: • Theory of resonance Raman scattering (RRS) of molecules in {sup 3}He liquid is proposed. • Fermi excitations give essential contribution to RRS. • RRS spectra of glyoxal molecule in {sup 3}He droplets are calculated. - Abstract: Light scattering in quantum liquid helium-3 may involve a unique mechanism – the creation and annihilation of atom excitations across the Fermi level. The density of states of particle–hole excitations in the low-energy limit is strongly enhanced as compared to that of collective excitations of phonons in helium-3. This makes possible to directly observe Fermi excitations in the resonant Raman scattering (RRS) by {sup 3}He droplets doped by impurity molecules. The RRS spectra essentially depend on the excitation frequency. In case of excitation in the anti-Stokes side of absorption the first order RRS is directly determined by the particle–hole excitations in the vicinity of the impurity molecule and the contribution of phonons mainly given by the localized spherical vibration. The calculations are made for a {sup 3}He droplet doped by a glyoxal molecule.

  2. Resonant Raman scattering in ion-beam-synthesized Mg2Si in a silicon matrix

    International Nuclear Information System (INIS)

    Baleva, M.; Zlateva, G.; Atanassov, A.; Abrashev, M.; Goranova, E.

    2005-01-01

    Resonant Raman scattering by ion beam synthesized in silicon matrix Mg 2 Si phase is studied. The samples are prepared with the implantation of 24 Mg + ions with dose 4x10 17 cm -2 and with two different energies 40 and 60 keV into (100)Si substrates. The far infrared spectra are used as criteria for the formation of the Mg 2 Si phase. The Raman spectra are excited with different lines of Ar + laser, with energies of the lines lying in the interval from 2.40 to 2.75 eV. The resonant scattering can be investigated using these laser lines, as far as according to the Mg 2 Si band structure, there are direct gaps with energies in the same region. The energy dependences of the scattered intensities in the case of the scattering by the allowed F 2g and the forbidden LO-type modes are experimentally obtained and theoretically interpreted. On the base of the investigation energies of the interband transitions in the Mg 2 Si are determined. It is found also that the resonant Raman scattering appears to be a powerful tool for characterization of a material with inclusions in it. In the particular case it is concluded that the Mg 2 Si phase is present in the form of a surface layer in the sample, prepared with implantation energy 40 keV and as low-dimensional precipitates, embedded in the silicon matrix, in the sample, prepared with the higher implantation energy

  3. Mössbauer forward scattering: time-domain spectra

    Energy Technology Data Exchange (ETDEWEB)

    Sadykov, E. K., E-mail: esadykov@kpfu.ru; Yurichuk, A. A.; Gainov, R. R.; Vagizov, F. G. [Kazan (Volga Region) Federal University (Russian Federation)

    2016-12-15

    The transmission of the Mössbauer radiation through an absorber being in the acoustic oscillation mode under forward scattering (FS) conditions has been analyzed. The modification of the existing models of the FS spectra (frequency and time) formation to the case of the arbitrary phase correlation of nuclear oscillations in the sample has been proposed. An adequate description of the time delayed experiments with the {sup 57}Fe Mössbauer resonance using the modulation of the single-photon wave packet by acoustic field has been obtained. One has been done in the frame of the Raman scattering of Mössbauer photons. The models extended this way can be used to control the degree of phase correlation of nuclear oscillations (or other processes) induced in the sample by external fields.

  4. Resonant X-ray Raman scattering for Al, Si and their oxides

    International Nuclear Information System (INIS)

    Szlachetko, J.; Berset, M.; Dousse, J.-Cl.; Fennane, K.; Szlachetko, M.; Barrett, R.; Hoszowska, J.; Kubala-Kukus, A.; Pajek, M.

    2005-01-01

    High-resolution measurements of the resonant X-ray Raman scattering (RRS) of Al and Si and their oxides were performed at the European Synchrotron Radiation Facility (ESRF) in Grenoble, France, using a von Hamos Bragg-type curved crystal spectrometer. To probe the influence of chemical effects on the RRS X-ray spectra, Al 2 O 3 and SiO 2 samples were also investigated. The X-ray RRS spectra were measured at different photon beam energies tuned below the K-absorption edge. The measured spectra are compared to results of RRS calculations based on the second-order perturbation theory within the Kramers-Heisenberg approach

  5. Enhancement of Raman scattering from monolayer graphene by photonic crystal nanocavities

    Science.gov (United States)

    Kimura, Issei; Yoshida, Masahiro; Sota, Masaki; Inoue, Taiki; Chiashi, Shohei; Maruyama, Shigeo; Kato, Yuichiro K.

    Monolayer graphene is an atomically thin two-dimensional material that shows strong Raman scattering, while photonic crystal nanocavities with small mode volumes allow for efficient optical coupling at the nanoscale. Here we demonstrate resonant enhancement of graphene Raman G' band by coupling to photonic crystal cavity modes. Hexagonal-lattice photonic crystal L3 cavities are fabricated from silicon-on-insulator substrates. and monolayer graphene sheets grown by chemical vapor deposition are transferred onto the nanocavities. Excitation wavelength dependence of Raman spectra show that the Raman intensity is enhanced when the G' peak is in resonance with the cavity mode. By performing imaging measurements, we confirm that such an enhancement is only observed at the cavity position. Work supported by JSPS KAKENHI Grant Numbers JP16K13613, JP25107002 and MEXT (Photon Frontier Network Program, Nanotechnology Platform).

  6. Density functional theory study on Herzberg-Teller contribution in Raman scattering from 4-aminothiophenol-metal complex and metal-4-aminothiophenol-metal junction

    Science.gov (United States)

    Liu, Shasha; Zhao, Xiuming; Li, Yuanzuo; Zhao, Xiaohong; Chen, Maodu

    2009-06-01

    Density functional theory (DFT) and time-dependent DFT calculations have been performed to investigate the Raman scattering spectra of metal-molecule complex and metal-molecule-metal junction architectures interconnected with 4-aminothiophenol (PATP) molecule. The simulated profiles of normal Raman scattering (NRS) spectra for the two complexes (Ag2-PATP and PATP-Au2) and the two junctions (Ag2-PATP-Au2 and Au2-PATP-Ag2) are similar to each other, but exhibit obviously different Raman intensities. Due to the lager static polarizabilities of the two junctions, which directly influence the ground state chemical enhancement in NRS spectra, the calculated normal Raman intensities of them are stronger than those of two complexes by the factor of 102. We calculate preresonance Raman scattering (RRS) spectra with incident light at 1064 nm, which is much lower than the S1 electronic transition energy of complexes and junctions. Ag2-PATP-Au2 and Au2-PATP-Ag2 junctions yield higher Raman intensities than those of Ag2-PATP and PATP-Au2 complexes, especially for b2 modes. This effect is mainly attributed to charge transfer (CT) between the metal gap and the PAPT molecule which results in the occurrence of CT resonance enhancement. The calculated pre-RRS spectra strongly depend on the electronic transition state produced by new structures. With excitation at 514.5 nm, the calculated pre-RRS spectra of two complexes and two junctions are stronger than those of with excitation at 1064 nm. A charge difference densities methodology has been used to visually describe chemical enhancement mechanism of RRS spectrum. This methodology aims at visualizing intermolecular CT which provides direct evidence of the Herzberg-Teller mechanism.

  7. Rapid thyroid dysfunction screening based on serum surface-enhanced Raman scattering and multivariate statistical analysis

    Science.gov (United States)

    Tian, Dayong; Lü, Guodong; Zhai, Zhengang; Du, Guoli; Mo, Jiaqing; Lü, Xiaoyi

    2018-01-01

    In this paper, serum surface-enhanced Raman scattering and multivariate statistical analysis are used to investigate a rapid screening technique for thyroid function diseases. At present, the detection of thyroid function has become increasingly important, and it is urgently necessary to develop a rapid and portable method for the detection of thyroid function. Our experimental results show that, by using the Silmeco-based enhanced Raman signal, the signal strength greatly increases and the characteristic peak appears obviously. It is also observed that the Raman spectra of normal and anomalous thyroid function human serum are significantly different. Principal component analysis (PCA) combined with linear discriminant analysis (LDA) was used to diagnose thyroid dysfunction, and the diagnostic accuracy was 87.4%. The use of serum surface-enhanced Raman scattering technology combined with PCA-LDA shows good diagnostic performance for the rapid detection of thyroid function. By means of Raman technology, it is expected that a portable device for the rapid detection of thyroid function will be developed.

  8. Surface-enhanced Raman scattering and density functional theory study of 1,4-benzenedithiol and its silver complexes.

    Science.gov (United States)

    Shao, Yangfan; Li, Chongyang; Feng, Yuanming; Lin, Wang

    2013-12-01

    This paper experimentally and theoretically investigated Raman and surface-enhanced Raman scattering (SERS) of 1,4-benzenedithiol (1,4-BDT). Density functional theory methods were used to study Raman scattering spectra of isolated 1,4-BDT and 1,4-BDT-Agn (n=2,4,6) complexes with B3LYP/6-311+g(d)(C,H,S)/Lanl2dz(Ag) basis set. A full assignment of the Raman spectrum of 1,4-BDT has been made based on the DFT analysis. The calculated data showed good agreement with experimental observations. The adsorption sites, metal cluster size, and HOMO-LUMO energies are discussed to give insight in the SERS mechanisms for 1,4-BDT molecules. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Raman spectroscopic studies of isotopic diatomic molecules and a technique for measuring stable isotope ratios using Raman scattering

    International Nuclear Information System (INIS)

    Harney, R.C.

    1976-01-01

    A method for measuring stable isotope ratios using Raman scattering has been developed. This method consists of simultaneously counting photons scattered out of a high-intensity laser beam by different isotopically-substituted molecules. A number of studies of isotopic diatomic molecules have been made. The Q-branches of the Raman spectra of the isotopic molecules 14 N 15 N and 16 O 18 O were observed at natural abundance in nitrogen and oxygen samples. Comparison of the ratios of the intensities of the Q-branches of the major nitrogen and oxygen isotopic molecules with mass spectrometric determinations of the isotopic compositions yielded scattering cross sections of 14 N 15 N relative to 14 N 14 N and 16 O 18 O relative to 16 O 16 O. These cross section ratios differ from unity, a difference which can be explained by considering nuclear mass effects on the Franck-Condon factors of the molecular transitions. The measured intensities of the 14 N 15 N and 16 O 18 O Q-branches provided the baseline data needed to make the previously-mentioned extrapolation. High-resolution (approximately 0.15 cm -1 ) spectra of the Q-branches of 14 N 14 N and 16 O 16 O yielded a direct determination of α/sub e/ (the difference between the rotational constant in the ground and first excited vibrational states) for these molecules. The measured values are in excellent agreement with those obtained by other means. Complete Raman spectra (pure rotation, rotation-vibration, and high-resolution Q-branch) were obtained on a sample of pure 18 O 18 O. Analysis of this data yielded the molecular parameters: the equilibrium internuclear separation r/sub e/, the moment of inertia I/sub e/, and the energy parameters α/sub e/, B/sub e/, and ΔG/sub 1 / 2 /. These are in good agreement with data obtained by microwave spectroscopy

  10. Blood analysis by Raman spectroscopy.

    Science.gov (United States)

    Enejder, Annika M K; Koo, Tae-Woong; Oh, Jeankun; Hunter, Martin; Sasic, Slobodan; Feld, Michael S; Horowitz, Gary L

    2002-11-15

    Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r(2) values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

  11. Resonant Raman and FTIR spectra of carbon doped GaN

    Science.gov (United States)

    Ito, S.; Kobayashi, H.; Araki, K.; Suzuki, K.; Sawaki, N.; Yamashita, K.; Honda, Y.; Amano, H.

    2015-03-01

    Intentionally carbon (C) doped (0 0 0 1)GaN was grown using C2H2 on a sapphire substrate by metalorganic vapor phase epitaxy. Optical spectra of the heavily doped samples were investigated at room temperature. In Raman spectra excited by the 325 nm line of a He-Cd laser, multiple LO phonon scattering signals up to 7th order were observed, and the A1(LO) phonon energy was determined to be 737.5 cm-1 (91.45 meV). In infrared reflectance spectra, on the other hand, a local vibration mode was found at 777.5 cm-1, which is attributed to a Ga-C bond in the GaN matrix suggesting that the C sits on an N site (CN). In spite of the strong suggestion of CN, the samples did not show p-type conduction. Possible origin of the carrier compensation is discussed in relation to the enhancement of defect related yellow luminescence in the photoluminescence spectra.

  12. Raman scattering tensors of tyrosine.

    Science.gov (United States)

    Tsuboi, M; Ezaki, Y; Aida, M; Suzuki, M; Yimit, A; Ushizawa, K; Ueda, T

    1998-01-01

    Polarized Raman scattering measurements have been made of a single crystal of L-tyrosine by the use of a Raman microscope with the 488.0-nm exciting beam from an argon ion laser. The L-tyrosine crystal belongs to the space group P2(1)2(1)2(1) (orthorhombic), and Raman scattering intensities corresponding to the aa, bb, cc, ab and ac components of the crystal Raman tensor have been determined for each prominent Raman band. A similar set of measurements has been made of L-tyrosine-d4, in which four hydrogen atoms on the benzene ring are replaced by deuterium atoms. The effects of NH3-->ND3 and OH-->OD on the Raman spectrum have also been examined. In addition, depolarization ratios of some bands of L-tyrosine in aqueous solutions of pH 13 and pH 1 were examined. For comparison with these experimental results, on the other hand, ab initio molecular orbital calculations have been made of the normal modes of vibration and their associated polarizability oscillations of the L-tyrosine molecule. On the basis of these experimental data and by referring to the results of the calculations, discussions have been presented on the Raman tensors associated to some Raman bands, including those at 829 cm-1 (benzene ring breathing), 642 cm-1 (benzene ring deformation), and 432 cm-1 (C alpha-C beta-C gamma bending).

  13. RAMAN-SPECTRA OF HUMAN DENTAL CALCULUS

    NARCIS (Netherlands)

    TSUDA, H; ARENDS, J

    1993-01-01

    Raman spectra of human dental calculus have been observed for the first time by use of micro-Raman spectroscopy. The spectral features of calculus were influenced easily by heating caused by laser irradiation. Therefore, the measurements were carried out at relatively low power (5 mW, 1-mu m spot

  14. Surface-enhanced Raman scattering from silver electrodes

    International Nuclear Information System (INIS)

    Trott, G.R.

    1982-01-01

    The chemical and physical origins of the anomalously large enhancement of the Raman scattering cross section for molecules adsorbed on silver electrodes in an electrochemical cell were investigated. The effect of the chemical reactions which occur during the anodization/activation procedure were studied using the Ag-CN system. It was shown that the function of the anodization process is to roughen the electrode surface and create an activated site for bonding to the cyanide. A new nonelectrochemical technique for activating the silver surface, along with a study of the enhanced cyanide Raman scattering in different background electrolytes, showed that the Raman active entity on the surface must be a silver-cyanide complex. In order to study the physical mechanism of the enhancement, the angular dependence of the scattered radiation was measured from pyridine adsorbed on an evaporated silver electrode. Both polycrystalline and single crystalline silver films were used. The angular dependence of the scattered radiation from these films showed that the metal surface was controlling the directional properties of the scattered radiation, and not the polarizability tensor of the adsorbate. Based on these experimental results, it was concluded that for weakly roughened silver electrodes the source of the anomalous enhancement is due to a resonant Raman scattering process

  15. Relaxation oscillations in stimulated Raman scattering

    International Nuclear Information System (INIS)

    Kachen, G.I.; Lowdermilk, W.H.

    1977-01-01

    Light pulses created by stimulated Raman scattering having been found to exhibit a complex time dependence which resembles relaxation oscillations. A focused laser pulse generated both forward and backward Raman emissions which appeared as a series of pulses with durations much shorter than the incident laser pulse. Time dependence of the Raman emission was observed directly by use of a streak camera. The number of observed pulses increased with the intensity of the incident pulse, while separation of the pulses in time depended on the length of the focal region. Beam focusing was incorporated in the coupled wave equations for stimulated Raman scattering. These rate equations were then solved numerically, and the results are in good qualitative agreement with the experimental observations. The short Raman pulses are created by a process associated with depletion of the incident laser pulse. This process occurs under a broad range of conditions

  16. Detection of mast cell secretion by using surface enhanced Raman scattering

    Science.gov (United States)

    Li, Juan; Li, Ren; Zheng, Liqin; Wang, Yuhua; Xie, Shusen; Lin, Juqiang

    2016-10-01

    Acupuncture can cause a remarkable increase in degranulation of the mast cells, which has attracted the interest of researchers since the 1980s. Surface-enhanced Raman scattering (SERS) could obtain biochemical information with high sensitivity and specificity. In this study, SERS was used to detect the degree of degranulation of mast cells according to different incubate time. Mast cells was incubated with culture medium for 0 h, 12 h and 24 h, then centrifuge the culture medium, decant the supernatant, and discard the mast cell. SERS was performed to obtain the biochemical fingerprinting signatures of the centrifuged medium. The spectra data are then analyzed by spectral peaks attribution and the principal component analysis (PCA). The measured Raman spectra of the two groups were separated well by PCA. It indicated that mast cells had secreted some substances into cultured medium though degranulation did not happen.

  17. Effects of Raman scattering in quantum state-preserving frequency conversion

    DEFF Research Database (Denmark)

    Friis, Søren Michael Mørk; Andersen, Lasse Mejling; Castaneda, Mario A. Usuga

    2014-01-01

    We analyse frequency conversion by Bragg scattering numerically including Raman scattering. The frequency configuration that performs the best under influence of Raman noise results in 95% conversion over a 3.25 THz bandwidth with a 2.5-dB noise figure.......We analyse frequency conversion by Bragg scattering numerically including Raman scattering. The frequency configuration that performs the best under influence of Raman noise results in 95% conversion over a 3.25 THz bandwidth with a 2.5-dB noise figure....

  18. Raman spectra of SDW superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Rout, G.C. [Condensed Matter Physics Group, Department of Physics, Government Science College, Chatrapur, Orissa 761 020 (India)]. E-mail: gcr@iopb.res.in; Bishoyi, K.C. [P.G. Department of Physics, F.M. College (Autonomous), Balasore, Orissa 756 001 (India); Behera, S.N. [Institute of Physics, Bhubaneswar 751 005 (India)

    2005-03-15

    We report the calculation of the phonon response of the coexistent spin density wave (SDW) and superconducting (SC) state and predict the observation of SC gap in the Raman spectra of rare-earth nickel borocarbide superconductors. The SDW state normally does not couple to the lattice and hence, the phonons in the system are not expected to be affected by the SDW state. But there is a possibility of observing SC gap mode in the Raman spectra of a SDW superconductor due to the coupling of the SC gap excitation to the Raman active phonons in the system via the electron-phonon (e-p) interaction. A theoretical model is used for the coexistent phase and electron-phonon interaction. Phonon Green's function is calculated by Zubarev's technique and the phonon self-energy due to e-p interaction which is given by electron density response function in the coexistent state corresponding to the SDW wave vector q = Q is evaluated. The results so obtained exhibit agreement with the experimental observations.

  19. Raman spectra of SDW superconductors

    International Nuclear Information System (INIS)

    Rout, G.C.; Bishoyi, K.C.; Behera, S.N.

    2005-01-01

    We report the calculation of the phonon response of the coexistent spin density wave (SDW) and superconducting (SC) state and predict the observation of SC gap in the Raman spectra of rare-earth nickel borocarbide superconductors. The SDW state normally does not couple to the lattice and hence, the phonons in the system are not expected to be affected by the SDW state. But there is a possibility of observing SC gap mode in the Raman spectra of a SDW superconductor due to the coupling of the SC gap excitation to the Raman active phonons in the system via the electron-phonon (e-p) interaction. A theoretical model is used for the coexistent phase and electron-phonon interaction. Phonon Green's function is calculated by Zubarev's technique and the phonon self-energy due to e-p interaction which is given by electron density response function in the coexistent state corresponding to the SDW wave vector q = Q is evaluated. The results so obtained exhibit agreement with the experimental observations

  20. Resonant Impulsive Stimulated Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari, A; Chesnoy, J

    1988-03-15

    Using a femtosecond dye laser, we observe in real-time vibrational oscillations excited by impulsive stimulated Raman scattering (ISRS) close to an electronic resonance. We perform single-beam Raman excitation and probe the driven coherence by a polarization-sensitive detection. We demonstrate for the first time impulsively Raman-induced dichroism, birefringence as well as frequency and time delay shifts. We analyse the characteristics of resonant ISRS on a vibrational mode of a dye molecule (malachite green) in solution.

  1. Resonant Impulsive Stimulated Raman Scattering

    International Nuclear Information System (INIS)

    Mokhtari, A.; Chesnoy, J.

    1988-01-01

    Using a femtosecond dye laser, we observe in real-time vibrational oscillations excited by impulsive stimulated Raman scattering (ISRS) close to an electronic resonance. We perform single-beam Raman excitation and probe the driven coherence by a polarization-sensitive detection. We demonstrate for the first time impulsively Raman-induced dichroism, birefringence as well as frequency and time delay shifts. We analyse the characteristics of resonant ISRS on a vibrational mode of a dye molecule (malachite green) in solution

  2. Subfemtosecond pulse generation by cascade-stimulated Raman scattering with modulated Raman excitation

    International Nuclear Information System (INIS)

    Wu Kun; Wu Jian; Zeng Heping

    2003-01-01

    Subfemtosecond (sub-fs) pulses can be generated by cascade-stimulated Raman scattering in a Raman medium with modulated Raman excitations, driven by two sufficiently intense laser beams, one of which is amplitude modulated. The nonadiabatic Raman interaction establishes a strong modulated Raman coherence, which supports compression of the generated broadband Raman sidebands to a train of sub-fs pulses regardless of whether the carrier frequencies of the driving lasers are tuned above, below or on two-photon Raman resonance. (letter to the editor)

  3. Surface enhancement Raman scattering of tautomeric thiobarbituric acid. Natural bond orbitals and B3LYP/6-311+G (d, p) assignments of the Fourier Infrared and Fourier Raman Spectra.

    Science.gov (United States)

    Soto, C A Téllez; Ramos, J M; Costa Junior, A C; Vieira, Laís S; Rangel, João L; Raniero, L; Fávero, Priscila P; Lemma, Tibebe; Ondar, Grisset F; Versiane, Otavio; Martin, A A

    2013-10-01

    Surface enhancement Raman scattering (SERS) of two tautomer of thiobarbituric acid was obtained using silver and gold nanoparticles. Large band enhancement in the region of the ν(C=S), ν(C=C), δ(CH2), and δ(CNH) vibrational modes was found. Natural bond analysis of the tautomer species revealed expressive values of charge transfer, principally from lone pair electron orbitals of the S, N, and O atoms. Complete vibrational assignment was done for the two tautomers using the B3LYP/6-311+G (d, p) procedure, band deconvolution analysis, and from a rigorous interpretation of the normal modes matrix. The calculated spectra agree well with the experimental ones. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Ultraviolet Raman scattering from persistent chemical warfare agents

    Science.gov (United States)

    Kullander, Fredrik; Wästerby, Pär.; Landström, Lars

    2016-05-01

    Laser induced Raman scattering at excitation wavelengths in the middle ultraviolet was examined using a pulsed tunable laser based spectrometer system. Droplets of chemical warfare agents, with a volume of 2 μl, were placed on a silicon surface and irradiated with sequences of laser pulses. The Raman scattering from V-series nerve agents, Tabun (GA) and Mustard gas (HD) was studied with the aim of finding the optimum parameters and the requirements for a detection system. A particular emphasis was put on V-agents that have been previously shown to yield relatively weak Raman scattering in this excitation band.

  5. Boron-purity-dependent Raman spectra of CaB6

    International Nuclear Information System (INIS)

    Song, M.; Yang, I. S.; Kim, J. Y.; Cho, B. K.

    2006-01-01

    We report significant differences in the Raman spectra of two different kinds of CaB 6 single crystals grown from boron with a purity of 99.9 % (3N) or 99.9999 % (6N). Our Raman spectra of CaB 6 (3N) show peaks around 781 (T 2g ), 1141 (E g ), and 1283 cm -1 (A 1g ), and they are very similar to previous Raman spectra of CaB 6 . The E g mode shows a characteristic double-peak feature due to an additional weak broad peak centered around 1158 cm -1 . However, the Raman spectra of CaB 6 (6N) show sharp peaks around 771 (T 2g ), 1137 (E g ), and 1266 cm -1 (A 1g ). The peak frequencies are down shifted as much as ∼17 cm -1 . In addition, no additional peak feature is observed for the E g mode so that the mode is symmetric in the case of CaB 6 (6N). The X-ray powder diffraction patterns for both CaB 6 (3N) and CaB 6 (6N) show that the lattice parameters are essentially the same. The majority of the impurity in the 99.9 %-pure (3N) boron is C. Thus, we doped CaB 6 (6N) with C, making Ca(B 0.995 C 0.005 ) 6 , and looked for differences in the Raman spectra. The Raman spectra of Ca(B 0.995 C 0.005 ) 6 are nearly identical to those of CaB 6 (6N), indicating that the differences between the Raman spectra of CaB 6 (3N) and CaB 6 (6N) are not due to a C impurity. The Raman results show that the presence of impurities, not the amount of them, is enough to trigger local symmetry breaking in CaB 6 . The broadening of T 2g , the additional E g2 mode and the asymmetry of A 1g in CaB 6 (3N) can be understood in terms of the symmetry of the arrangements of the boron octahedra lowered by local symmetry breaking.

  6. [Micro-Raman and fluorescence spectra of several agrochemicals].

    Science.gov (United States)

    Xiao, Yi-lin; Zhang, Peng-xiang; Qian, Xiao-fan

    2004-05-01

    Raman and fluorescence spectra from several agrochemicals were measured, which are sold for the use in vegetables, fruits and grains. Characteristic vibration Raman peaks from some of the agrochemicals were recorded, hence the spectra can be used for their identification. Other marketed agrochemicals demonstrated strong fluorescence under 514.5 nm excitation. It was found that the fluorescence spectra of the agrochemicals are very different. According to these results one can detect the trace amount of agrochemicals left on the surface of fruits, vegetables and grains in situ and conveniently.

  7. Pump Side-scattering in Ultra-powerful Backward Raman Amplifiers

    International Nuclear Information System (INIS)

    Solodov, A.A.; Malkin, V.M.; Fisch, N.J.

    2004-01-01

    Extremely large laser power might be obtained by compressing laser pulses through backward Raman amplification (BRA) in plasmas. Premature Raman backscattering of a laser pump by plasma noise might be suppressed by an appropriate detuning of the Raman resonance, even as the desired amplification of the seed persists with a high efficiency. In this paper, we analyze side-scattering of laser pumps by plasma noise in backward Raman amplifiers. Though its growth rate is smaller than that of backscattering, the side-scattering can nevertheless be dangerous, because of a longer path of side-scattered pulses in plasmas and because of an angular dependence of the Raman resonance detuning. We show that side-scattering of laser pumps by plasma noise in BRA might be suppressed to a tolerable level at all angles by an appropriate combination of two detuning mechanisms associated with plasma density gradient and pump chirp

  8. The Raman and SERS spectra of indigo and indigo-Ag2 complex: DFT calculation and comparison with experiment.

    Science.gov (United States)

    Ricci, Marilena; Lofrumento, Cristiana; Becucci, Maurizio; Castellucci, Emilio M

    2018-01-05

    Using time-dependent density functional theory in conjunction with B3LYP functional and LANL2DZ/6-31+g(d,p) basis sets, static and pre-resonance Raman spectra of the indigo-Ag 2 complex have been calculated. Structure optimization, excitation energies and pre-resonance Raman spectra of the indigo molecule have been obtained at the same level of theory. The available experimental Raman spectra at 1064, 785 and 514nm and the SERS spectra at 785 and 514nm have been well reproduced by the calculation. Experimental SERS spectra are confronted with the calculated pre-resonance Raman spectra obtained for the indigo-Ag 2 complex. The Raman activities calculated under the infinite lifetime approximation show a strong dependence upon the proximity to the energy and the oscillator strength of the excitation electronic transition. The comparison of the integrated EFs for indigo and indigo-Ag 2 calculated Raman spectra, gave some hints as to the enhancement mechanisms acting for the different excitation wavelengths. Whereas for excitation at a wavelength corresponding to 785nm, the enhancement mechanism for the Raman spectrum of the metal complex seems the chemical one, the strong increment (ten times) of the integrated EF of the Raman spectra of the complex in the case of 514nm excitation, suggests the onset of other enhancement mechanisms. Assuming that intra-cluster transitions with high oscillator strength can be thought of as to mimic surface plasmons excitations, we suggest the onset of the electromagnetic mechanisms (EM) as the origin of the Raman spectrum enhancement. Nevertheless, other enhancement effects cannot be ruled out, as a new molecular transition gains strength in the proximity of the excitation wavelength, as a consequence of the symmetry lowering of the molecule in the complex. A large variation across vibrational modes, by a factor of at least 10 4 , was found for the EFs. This large variation in the EFs can indicate that B-term Herzberg-Teller scattering

  9. Inter-tetrahedra bond angle of permanently densified silicas extracted from their Raman spectra

    International Nuclear Information System (INIS)

    Hehlen, B

    2010-01-01

    Relative Raman scattering intensities are obtained in three samples of vitreous silica of increasing density. The variation of the intensity upon densification is very different for bending and stretching modes. For the former we find a Raman coupling-to-light coefficient C B ∝ω 2 . A comparative intensity and frequency dependence of the Raman spectral lines in the three glasses is performed. Provided the Raman spectra are normalized by C B , there exists a simple relation between the Si-O-Si bond angle and the frequency of all O-bending motions, including those of fourfold (n = 4) and threefold (n = 3) rings. For 20% densification we find a reduction of ∼5.7 deg. of the maximum of the network angle distribution, a value in very close agreement with previous NMR experiments. The threefold and fourfold rings are weakly perturbed by the densification, with a bond angle reduction of ∼0.5 deg. for the former.

  10. Electron Raman scattering in a HgS/CdS spherical quantum dot quantum well

    International Nuclear Information System (INIS)

    Zhong Qinghu; Lai Liping

    2013-01-01

    Electron Raman scattering (ERS) is investigated in a spherical HgS/CdS quantum dot quantum well (QDQW). The differential cross section (DCS) is calculated as a function of the scattering frequency and the sizes of QDQW. Single parabolic conduction and valence bands are assumed. The selection rules for the processes are studied. Singularities in the spectra are found and interpreted. The ERS studied here can be used to provide direct information about the electron band structure of these systems. (semiconductor physics)

  11. The effect of nonlocal dielectric response on the surface-enhanced Raman and fluorescence spectra of molecular systems

    Science.gov (United States)

    Wei, Yong; Pei, Huan; Li, Li; Zhu, Yanying

    2018-06-01

    We present a theoretical study on the influence of the nonlocal dielectric response on surface-enhanced resonant Raman scattering (SERRS) and fluorescence (SEF) spectra of a model molecule confined in the center of a Ag nanoparticle (NP) dimer. In the simulations, the nonlocal dielectric response caused by the electron–hole pair generation in Ag NPs was computed with the d-parameter theory, and the scattering spectra of a model molecule representing the commonly used fluorescent dye rhodamine 6G (R6G) were obtained by density-matrix calculations. The influence of the separation between Ag NP dimers on the damping rate and scattering spectra with and without the nonlocal response were systematically analyzed. The results show that the nonlocal dielectric response is very sensitive to the gap distance of the NP dimers, and it undergoes much faster decay with the increase of the separation than the radiative and energy transfer rates. The Raman and fluorescence peaks as simulated with the nonlocal dielectric response are relative weaker than that without the nonlocal effect for smaller NP separations because the extra decay rates of the nonlocal effect could reduce both the population of the excited state and the interband coherence between the ground and excited states. Our result also indicates that the nonlocal effect is more prominent on the SEF process than the SERRS process.

  12. Difference Raman spectroscopy of DNA molecules

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  13. Chloride ion-dependent surface-enhanced Raman scattering study of biotin on the silver surface

    International Nuclear Information System (INIS)

    Liu Fangfang; Gu Huaimin; Yuan Xiaojuan; Dong Xiao; Lin Yue

    2011-01-01

    In the present paper, the surface enhanced Raman scattering (SERS) technique was employed to study the SERS spectra of biotin molecules formed on the silver surface. The adsorption geometries of biotin molecules on the silver surface were analyzed based on the SERS data. It can be found that most vibration modes show a Raman shift in silver sol after the addition of sodium chloride solution. In addition, The Raman signals of biotin become weaker and weaker with the increase of the concentration of sodium chloride. This may be due to that the interaction between chloride ions and silver particles is stronger than the interaction between biotin molecules and silver particles. When the concentration of sodium chloride in silver colloid is higher than 0.05mol/L, superfluous chloride ions may form an absorption layer so that biotin can not be adsorbed on silver surface directly. The changes in intensity and profile shape in the SERS spectra suggest different adsorption behavior and surface-coverage of biotin on silver surface. The SERS spectra of biotin suggest that the contribution of the charge transfer mechanism to SERS may be dominant.

  14. Micro-Raman scattering in ZnTe thin films

    International Nuclear Information System (INIS)

    Larramendi, E. M.; Gutierrez Z-B, K.; Hernandez, E.; Melo, O. de; Berth, G.; Wiedemeier, V.; Lischka, K; Schikora, D.; Woggon, U.

    2008-01-01

    In this work we present micro-raman measurements on ZnTe thin films grown by isothermal closed space sublimation on GaAs(001) substrates in helium and nitrogen atmospheres. Micro-raman spectra were recorded at room temperature using the backscattering geometry (illuminated spot: 3 μm2, 0.3 cm-1 of resolution and the line 532 nm of a DPSSL as power excitation). Up to four order LO-phonon replicas and no peak from TO phonon were observed in the micro-raman spectra as evidence of the epitaxial character and good quality of the films (the TO mode is forbidden according to the selection rules for backscattering along [001] of this heterostructure). The micro-raman spectra also revealed two features at low energy, which have been assigned incorrectly in recent works. We demonstrate that these raman peaks can be associated to the presence of few monolayers of crystalline tellurium or its oxides on the surface of the films. These features were not observed in micro-raman spectra of as grown ZnTe films terminated in a Zn surface. However, they were detected after a prolonged exposure of the samples to air. In addition, it is shown that this effect is accelerated under a high power laser excitation (laser annealing) as used in conventional micro-Raman measurement setups. Preliminary results that suggest the inclusion of nitrogen in ZnTe structure are also shown. (Full text)

  15. High-resolution nonresonant x-ray Raman scattering study on rare earth phosphate nanoparticles

    NARCIS (Netherlands)

    Huotari, Simo; Suljoti, Edlira; Sahle, Christoph J.; Raedel, Stephanie; Monaco, Giulio; de Groot, Frank M. F.

    2015-01-01

    We report high-resolution x-ray Raman scattering studies of high-order multipole spectra of rare earth 4d -> 4f excitations (the N-4,N-5 absorption edge) in nanoparticles of the phosphates LaPO4, CePO4, PrPO4, and NdPO4. We also present corresponding data for La 5p -> 5d excitations (the O-2,O-3

  16. Enhanced Raman scattering and nonlinear conductivity in Ag-doped hollow ZnO microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Tringe, Joseph W.; Levie, Harold W.; McCall, Scott K.; Teslich, Nick E.; Wall, Mark A.; Orme, Christine A.; Matthews, Manyalibo J. [Lawrence Livermore National Laboratory, Livermore, CA (United States)

    2012-10-15

    Hollow spherical ZnO particles doped with Ag were synthesized with a two-step oxidation and sublimation furnace annealing process. Ag nanoparticle precipitates, as observed by transmission electron microscopy, were present in the polycrystalline ZnO matrix at Ag concentrations below 0.02 mol%, significantly below the 0.8 mol% solubility limit for Ag in ZnO. Enhanced Raman scattering of ZnO phonon modes is observed, increasing with Ag nanoparticle concentration. A further enhancement in Raman scattering due to resonance effects was observed for LO phonons excited by 2.33-eV photons as compared with Raman scattering under 1.96-eV excitation. Room-temperature photoluminescence spectra showed both a near-band-edge emission due to free exciton transitions and a mid-gap transition due to the presence of singly ionized oxygen vacancies. ZnO:Ag particles were measured electrically in a packed column and in monolithic form, and in both cases displayed nonlinear current-voltage characteristics similar to those previously observed in sintered ZnO:Ag monoliths where Ag-enhanced disorder at grain boundaries is thought to control current transport. We demonstrate therefore that Ag simultaneously modifies the electrical and optical properties of ZnO particles through the introduction of vacancies and other defects. (orig.)

  17. Forbidden Raman scattering processes. I. General considerations and E1--M1 scattering

    International Nuclear Information System (INIS)

    Harney, R.C.

    1979-01-01

    The generalized theory of forbidden Raman scattering processes is developed in terms of the multipole expansion of the electromagnetic interaction Hamiltonian. Using the general expressions, the theory of electric dipole--magnetic dipole (E1--M1) Raman scattering is derived in detail. The 1 S 0 → 3 P 1 E1--M1 Raman scattering cross section in atomic magnesium is calculated for two applicable laser wavelengths using published f-value data. Since resonantly enhanced cross sections larger than 10 -29 cm 2 /sr are predicted it should be possible to experimentally observe this scattering phenomenon. In addition, by measuring the frequency dependence of the cross section near resonance, it may be possible to directly determine the relative magnitudes of the Axp and AxA contributions to the scattering cross section. Finally, possible applications of the effect in atomic and molecular physics are discussed

  18. Enhanced optical coupling and Raman scattering via microscopic interface engineering

    Science.gov (United States)

    Thompson, Jonathan V.; Hokr, Brett H.; Kim, Wihan; Ballmann, Charles W.; Applegate, Brian E.; Jo, Javier A.; Yamilov, Alexey; Cao, Hui; Scully, Marlan O.; Yakovlev, Vladislav V.

    2017-11-01

    Spontaneous Raman scattering is an extremely powerful tool for the remote detection and identification of various chemical materials. However, when those materials are contained within strongly scattering or turbid media, as is the case in many biological and security related systems, the sensitivity and range of Raman signal generation and detection is severely limited. Here, we demonstrate that through microscopic engineering of the optical interface, the optical coupling of light into a turbid material can be substantially enhanced. This improved coupling facilitates the enhancement of the Raman scattering signal generated by molecules within the medium. In particular, we detect at least two-orders of magnitude more spontaneous Raman scattering from a sample when the pump laser light is focused into a microscopic hole in the surface of the sample. Because this approach enhances both the interaction time and interaction region of the laser light within the material, its use will greatly improve the range and sensitivity of many spectroscopic techniques, including Raman scattering and fluorescence emission detection, inside highly scattering environments.

  19. Dental caries imaging using hyperspectral stimulated Raman scattering microscopy

    Science.gov (United States)

    Wang, Zi; Zheng, Wei; Jian, Lin; Huang, Zhiwei

    2016-03-01

    We report the development of a polarization-resolved hyperspectral stimulated Raman scattering (SRS) imaging technique based on a picosecond (ps) laser-pumped optical parametric oscillator system for label-free imaging of dental caries. In our imaging system, hyperspectral SRS images (512×512 pixels) in both fingerprint region (800-1800 cm-1) and high-wavenumber region (2800-3600 cm-1) are acquired in minutes by scanning the wavelength of OPO output, which is a thousand times faster than conventional confocal micro Raman imaging. SRS spectra variations from normal enamel to caries obtained from the hyperspectral SRS images show the loss of phosphate and carbonate in the carious region. While polarization-resolved SRS images at 959 cm-1 demonstrate that the caries has higher depolarization ratio. Our results demonstrate that the polarization resolved-hyperspectral SRS imaging technique developed allows for rapid identification of the biochemical and structural changes of dental caries.

  20. A novel method for detection of phosphorylation in single cells by surface enhanced Raman scattering (SERS using composite organic-inorganic nanoparticles (COINs.

    Directory of Open Access Journals (Sweden)

    Catherine M Shachaf

    Full Text Available Detection of single cell epitopes has been a mainstay of immunophenotyping for over three decades, primarily using fluorescence techniques for quantitation. Fluorescence has broad overlapping spectra, limiting multiplexing abilities.To expand upon current detection systems, we developed a novel method for multi-color immuno-detection in single cells using "Composite Organic-Inorganic Nanoparticles" (COINs Raman nanoparticles. COINs are Surface-Enhanced Raman Scattering (SERS nanoparticles, with unique Raman spectra. To measure Raman spectra in single cells, we constructed an automated, compact, low noise and sensitive Raman microscopy device (Integrated Raman BioAnalyzer. Using this technology, we detected proteins expressed on the surface in single cells that distinguish T-cells among human blood cells. Finally, we measured intracellular phosphorylation of Stat1 (Y701 and Stat6 (Y641, with results comparable to flow cytometry.Thus, we have demonstrated the practicality of applying COIN nanoparticles for measuring intracellular phosphorylation, offering new possibilities to expand on the current fluorescent technology used for immunoassays in single cells.

  1. A novel method for detection of phosphorylation in single cells by surface enhanced Raman scattering (SERS) using composite organic-inorganic nanoparticles (COINs).

    Science.gov (United States)

    Shachaf, Catherine M; Elchuri, Sailaja V; Koh, Ai Leen; Zhu, Jing; Nguyen, Lienchi N; Mitchell, Dennis J; Zhang, Jingwu; Swartz, Kenneth B; Sun, Lei; Chan, Selena; Sinclair, Robert; Nolan, Garry P

    2009-01-01

    Detection of single cell epitopes has been a mainstay of immunophenotyping for over three decades, primarily using fluorescence techniques for quantitation. Fluorescence has broad overlapping spectra, limiting multiplexing abilities. To expand upon current detection systems, we developed a novel method for multi-color immuno-detection in single cells using "Composite Organic-Inorganic Nanoparticles" (COINs) Raman nanoparticles. COINs are Surface-Enhanced Raman Scattering (SERS) nanoparticles, with unique Raman spectra. To measure Raman spectra in single cells, we constructed an automated, compact, low noise and sensitive Raman microscopy device (Integrated Raman BioAnalyzer). Using this technology, we detected proteins expressed on the surface in single cells that distinguish T-cells among human blood cells. Finally, we measured intracellular phosphorylation of Stat1 (Y701) and Stat6 (Y641), with results comparable to flow cytometry. Thus, we have demonstrated the practicality of applying COIN nanoparticles for measuring intracellular phosphorylation, offering new possibilities to expand on the current fluorescent technology used for immunoassays in single cells.

  2. Raman scattering studies of YBa2Cu3O7-x thin films grown by chemical vapor deposition and metal-organic deposition

    International Nuclear Information System (INIS)

    Lee, E.; Yoon, S.; Um, Y.M.; Jo, W.; Seo, C.W.; Cheong, H.; Kim, B.J.; Lee, H.G.; Hong, G.W.

    2007-01-01

    We present results of Raman scattering studies of superconducting YBa 2 Cu 3 O 7-x (YBCO) films grown by chemical vapor deposition and metal-organic deposition methods. It is shown by X-ray diffraction that all the as-grown YBCO films have a highly c-axis oriented and in-plane aligned texture. Raman scattering measurements were used to investigate optical phonon modes, oxygen contents, structural properties, and second-phases of the YBCO coated conductors. Raman spectra of YBCO films with lower-transport qualities exhibit additional phonon modes at ∼300 cm -1 , ∼600 cm -1 , and ∼630 cm -1 , which are related to second-phases such as Ba 2 Cu 3 O 5.9 and BaCuO 2 . Our results strongly suggest that Raman scattering be useful for optimizing YBCO film growth conditions

  3. Direct visual evidence of end-on adsorption geometry of pyridine on silver surface investigated by surface enhanced Raman scattering and density functional theory calculations.

    Science.gov (United States)

    Bhunia, Snehasis; Forster, Stefan; Vyas, Nidhi; Schmitt, Hans-Christian; Ojha, Animesh K

    2015-12-05

    Fourier transform Raman (FT-Raman) spectra of neat pyridine (Py) and surface enhanced Raman scattering (SERS) spectra of Py with silver nanoparticles (AgNPs) solution at different molar concentrations (X=1.5M, 1.0M, 0.50 M, 0.25 M, and 0.125 M) were recorded using 1064 nm excitation wavelength. The intensity of Raman bands at ∼1003 (ν11) and ∼1035 (ν21) cm(-1) of Py is enhanced in the SERS spectra. Two new Raman bands were observed at ∼1009 (ν12) and ∼1038 (ν22) cm(-1) in the SERS spectra. These bands correspond to the ring breathing vibrations of Py molecules adsorbed at the AgNPs surface. The value of intensity ratios (I12/I11) and (I21/I22) is increased with dilution and attains a maximum value at X=0.5M and upon further dilution (0.25 and 0.125 M) it drops gradually. The theoretically calculated Raman spectra were found to be in good agreement with experimentally observed Raman spectra. Both, experimental and theoretical investigations have confirmed that the Py interacts with AgNPs via the end-on geometry. Copyright © 2015 Elsevier B.V. All rights reserved.

  4. Detection and Implications of Laser-Induced Raman Scattering at Astronomical Observatories

    Directory of Open Access Journals (Sweden)

    Frédéric P. A. Vogt

    2017-06-01

    Full Text Available Laser guide stars employed at astronomical observatories provide artificial wavefront reference sources to help correct (in part the impact of atmospheric turbulence on astrophysical observations. Following the recent commissioning of the 4 Laser Guide Star Facility (4LGSF on Unit Telescope 4 (UT4 of the Very Large Telescope (VLT, we characterize the spectral signature of the uplink beams from the 22-W lasers to assess the impact of laser scattering from the 4LGSF on science observations. We use the Multi-Unit Spectroscopic Explorer (MUSE optical integral field spectrograph mounted on the Nasmyth B focus of UT4 to acquire spectra at a resolution of R≅3000 of the uplink laser beams over the wavelength range of 4750 Å–9350 Å. We report the first detection of laser-induced Raman scattering by N_{2}, O_{2}, CO_{2}, H_{2}O, and (tentatively CH_{4} molecules in the atmosphere above the astronomical observatory of Cerro Paranal. In particular, our observations reveal the characteristic spectral signature of laser photons—but 480 Å to 2210 Å redder than the original laser wavelength of 5889.959 Å—landing on the 8.2-m primary mirror of UT4 after being Raman-scattered on their way up to the sodium layer. Laser-induced Raman scattering, a phenomenon not usually discussed in the astronomical context, is not unique to the observatory of Cerro Paranal, but it is common to any astronomical telescope employing a laser guide star (LGS system. It is thus essential for any optical spectrograph coupled to a LGS system to thoroughly handle the possibility of a Raman spectral contamination via a proper baffling of the instrument and suitable calibrations procedures. These considerations are particularly applicable for the HARMONI optical spectrograph on the upcoming Extremely Large Telescope (ELT. At sites hosting multiple telescopes, laser-collision-prediction tools should also account for the presence of Raman emission from the uplink laser beam

  5. Excited-state Raman spectroscopy with and without actinic excitation: S1 Raman spectra of trans-azobenzene

    International Nuclear Information System (INIS)

    Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A.

    2014-01-01

    We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S 1 and S 0 spectra of trans-azobenzene in n-hexane. The S 1 spectra were also measured conventionally, upon nπ* (S 0 → S 1 ) actinic excitation. The results are discussed and compared to earlier reports

  6. Raman-scattering results from Y1-xCaxSr2Cu2GaO7

    International Nuclear Information System (INIS)

    Salamon, D.; Liu, R.; Klein, M.V.; Groenke, D.A.; Poeppelmeier, K.R.; Dabrowski, B.; Han, P.D.; Payne, D.A.

    1993-01-01

    We present a Raman-scattering study of Y 1-x Ca x Sr 2 Cu 2 GaO 7 for both the x=0 parent compound and doped compositions with x=0.25 and x=0.40. Extrapolation from YBa 2 Cu 3 O 7-d and other cuprates allows us to assign many of the Raman-active phonon modes in the x=0 material, as well as identify a two-magnon scattering peak, a second-order phonon scattering peak, and a Raman continuum out to 4000 cm -1 . Despite compositional inhomogeneities, the doped superconducting samples show some of the same low-energy phonon features as the x=0 material. There is, however, a doping-dependent shift in the positions of features in the 500--700 cm -1 range, possibly due to Ca locating on Sr sites instead of Y sites. The relative intensities of the phonon peaks in the doped material are also changed from the insulator (x=0), suggesting that a resonant Raman phenomenon is occurring. The temperature-dependent spectra show what appears to be a superconducting dip in the background intensity, but the low superconducting fractions in these samples make this difficult to verify. The doped material also has a Raman continuum out to 4000 cm -1 just as in the x=0 samples, but with the two-magnon and second-order phonon scattering peaks significantly reduced in intensity. This may be a result of changes in the long-range ordering, or another manifestation of the same resonance phenomena occurring at lower energies. Single-crystal samples of the doped material Y 1-x Ca x Sr 2 Cu 2 GaO 7 are necessary for a more conclusive Raman study

  7. Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

    OpenAIRE

    Yanli Liu; Xifeng Yang; Dunjun Chen; Hai Lu; Rong Zhang; Youdou Zheng

    2015-01-01

    The temperature-dependent stress state in the AlGaN barrier layer of AlGaN/GaN heterostructure grown on sapphire substrate was investigated by ultraviolet (UV) near-resonant Raman scattering. Strong scattering peak resulting from the A1(LO) phonon mode of AlGaN is observed under near-resonance condition, which allows for the accurate measurement of Raman shifts with temperature. The temperature-dependent stress in the AlGaN layer determined by the resonance Raman spectra is consistent with th...

  8. Raman scattering study of phonons in Bi-based superconductor thin films

    International Nuclear Information System (INIS)

    Mejia-Garcia, C.; Diaz-Valdes, E.; Contreras-Puente, G.; Lopez-Lopez, J.L.; Jergel, M.; Morales, A.

    2004-01-01

    Raman spectra were obtained from samples of Bi-Pb-Sr-Ca-Cu-O (BPSCCO) thin films after varying several growth parameters, such as covering material, annealing time (t R ), annealing temperature (T R ), and nominal lead content (x). Thin films with the nominal composition Bi 1.4 Pb x Sr 2 Ca 2 Cu 3 O δ were grown on MgO substrates by a spray pyrolysis technique, followed by a solid state reaction. The results of Raman scattering measurements at room temperature show a series of vibrational optical modes within the range 300-900 cm -1 . The assignment of these modes was made by involving mainly the 2212 and 2223 phases and was confirmed by both X-ray diffraction and resistance in dependence of the temperature (R-T) measurements as well

  9. Raman scattering investigation of the water-bridge phenomenon: Some preliminary results

    Directory of Open Access Journals (Sweden)

    Francesco Aliotta

    2010-09-01

    Full Text Available A floating water-bridge is formed if a high-voltage direct current is applied between two beakers filled of chemically pure water. Raman spectra of the OH-stretching region have been obtained at ambient condition of temperature and pressure. These preliminary results seem to indicate that the hydrogen-bond structure is only slightly modified by the presence of the electric field applied to form the floating water-bridge in agreement with recent neutron scattering investigation. In fact, the polarized Raman spectrum of the pure water and of the water-bridge is almost superimposable. We are planning to carry out further spectroscopic analysis, at different thermodynamic conditions, for better understanding the role played by the hydrogen-bond in driving the formation of the floating water-bridge.

  10. Polarized Raman spectroscopy of bone tissue: watch the scattering

    Science.gov (United States)

    Raghavan, Mekhala; Sahar, Nadder D.; Wilson, Robert H.; Mycek, Mary-Ann; Pleshko, Nancy; Kohn, David H.; Morris, Michael D.

    2010-02-01

    Polarized Raman spectroscopy is widely used in the study of molecular composition and orientation in synthetic and natural polymer systems. Here, we describe the use of Raman spectroscopy to extract quantitative orientation information from bone tissue. Bone tissue poses special challenges to the use of polarized Raman spectroscopy for measurement of orientation distribution functions because the tissue is turbid and birefringent. Multiple scattering in turbid media depolarizes light and is potentially a source of error. Using a Raman microprobe, we show that repeating the measurements with a series of objectives of differing numerical apertures can be used to assess the contributions of sample turbidity and depth of field to the calculated orientation distribution functions. With this test, an optic can be chosen to minimize the systematic errors introduced by multiple scattering events. With adequate knowledge of the optical properties of these bone tissues, we can determine if elastic light scattering affects the polarized Raman measurements.

  11. Temperature Dependence of Polarized Low Wavenumber Raman Spectra of Aminopropylsilanetriol Polymer

    International Nuclear Information System (INIS)

    V, Volovsek; L, Bistrcic; K, Furic; V, Daanic; I, Movre Sapic

    2006-01-01

    Low wavenumber polarized Raman spectra of aminopropylsilanetriol (APST) polymer deposited on PVC substrate were measured in the temperature range from 300 K to 78 K. In the low wavenumber Raman spectra of these samples a very strong Bose band was observed. The best results in modeling the low wavenumber Raman spectra were achieved with the exponential correlation function of disorder G dis (ν) = exp(-r/R c )using three contributions: transversal and longitudinal acoustic phonons and molecular vibration. Results suggest medium range ordered ladder structure, stacked in layers with different orientations of ladders

  12. Raman microspectroscopy, surface-enhanced Raman scattering microspectroscopy, and stable-isotope Raman microspectroscopy for biofilm characterization.

    Science.gov (United States)

    Ivleva, Natalia P; Kubryk, Patrick; Niessner, Reinhard

    2017-07-01

    Biofilms represent the predominant form of microbial life on our planet. These aggregates of microorganisms, which are embedded in a matrix formed by extracellular polymeric substances, may colonize nearly all interfaces. Detailed knowledge of microorganisms enclosed in biofilms as well as of the chemical composition, structure, and functions of the complex biofilm matrix and their changes at different stages of the biofilm formation and under various physical and chemical conditions is relevant in different fields. Important research topics include the development and improvement of antibiotics and medical devices and the optimization of biocides, antifouling strategies, and biological wastewater treatment. Raman microspectroscopy is a capable and nondestructive tool that can provide detailed two-dimensional and three-dimensional chemical information about biofilm constituents with the spatial resolution of an optical microscope and without interference from water. However, the sensitivity of Raman microspectroscopy is rather limited, which hampers the applicability of Raman microspectroscopy especially at low biomass concentrations. Fortunately, the resonance Raman effect as well as surface-enhanced Raman scattering can help to overcome this drawback. Furthermore, the combination of Raman microspectroscopy with other microscopic techniques, mass spectrometry techniques, or particularly with stable-isotope techniques can provide comprehensive information on monospecies and multispecies biofilms. Here, an overview of different Raman microspectroscopic techniques, including resonance Raman microspectroscopy and surface-enhanced Raman scattering microspectroscopy, for in situ detection, visualization, identification, and chemical characterization of biofilms is given, and the main feasibilities and limitations of these techniques in biofilm research are presented. Future possibilities of and challenges for Raman microspectroscopy alone and in combination with other

  13. Influence of a photoexcited electron-hole plasma on the Raman scattering spectra of YBa2Cu3Ox single crystals

    International Nuclear Information System (INIS)

    Goncharov, A.F.; Denisov, V.N.; Mavrin, B.N.; Podobedov, V.B.

    1988-01-01

    The Raman spectra of tetragonal YBa 2 Cu 3 O x crystals in the region of ∼500 cm -1 were determined using different power densities I 0 of the exciting radiation of wavelengths 4,880, 5,145, 5,321, and 6,471 angstrom at temperatures 80-300 K. An increase in I 0 revealed changes in the spectra due to interference of the electron continuum with a 470 cm -1 phonon and also due to activation of 560-590 cm -1 dipole vibrations because of interaction of photocarriers with the crystal lattice. An analysis of the spectra yielded the electron-phonon interaction constant. The changes in the spectra were of resonant nature, but they were absent in the case of the excitation wavelengths 5,321 and 6,471 angstrom. A triple multichannel Raman spectrometer, developed by the authors, made it possible to record simultaneously a spectral interval of 500 cm -1 in the range ≥ 25 cm -1 on excitation with cw laser radiation

  14. Inverse Raman scattering in silicon: A free-carrier enhanced effect

    International Nuclear Information System (INIS)

    Solli, D. R.; Koonath, P.; Jalali, B.

    2009-01-01

    Stimulated Raman scattering has been harnessed to produce the first silicon lasers and amplifiers. The Raman effect can also produce intensity-dependent nonlinear loss through a corollary process, inverse Raman scattering (IRS). This process has never been observed in a semiconductor. We demonstrate IRS in silicon--a process that is substantially modified by optically generated free carriers--achieving attenuation levels >15 dB with a pump intensity of 4 GW/cm 2 . Surprisingly, free-carrier absorption, the detrimental effect that generally suppresses nonlinear effects in silicon, actually facilitates IRS by delaying the onset of contamination from coherent anti-Stokes Raman scattering. Silicon-based IRS could be a valuable tool for chip-scale signal processing.

  15. The impact of vibrational Raman scattering of air on DOAS measurements of atmospheric trace gases

    Science.gov (United States)

    Lampel, J.; Frieß, U.; Platt, U.

    2015-09-01

    In remote sensing applications, such as differential optical absorption spectroscopy (DOAS), atmospheric scattering processes need to be considered. After inelastic scattering on N2 and O2 molecules, the scattered photons occur as additional intensity at a different wavelength, effectively leading to "filling-in" of both solar Fraunhofer lines and absorptions of atmospheric constituents, if the inelastic scattering happens after the absorption. Measured spectra in passive DOAS applications are typically corrected for rotational Raman scattering (RRS), also called Ring effect, which represents the main contribution to inelastic scattering. Inelastic scattering can also occur in liquid water, and its influence on DOAS measurements has been observed over clear ocean water. In contrast to that, vibrational Raman scattering (VRS) of N2 and O2 has often been thought to be negligible, but it also contributes. Consequences of VRS are red-shifted Fraunhofer structures in scattered light spectra and filling-in of Fraunhofer lines, additional to RRS. At 393 nm, the spectral shift is 25 and 40 nm for VRS of O2 and N2, respectively. We describe how to calculate VRS correction spectra according to the Ring spectrum. We use the VRS correction spectra in the spectral range of 420-440 nm to determine the relative magnitude of the cross-sections of VRS of O2 and N2 and RRS of air. The effect of VRS is shown for the first time in spectral evaluations of Multi-Axis DOAS data from the SOPRAN M91 campaign and the MAD-CAT MAX-DOAS intercomparison campaign. The measurements yield in agreement with calculated scattering cross-sections that the observed VRS(N2) cross-section at 393 nm amounts to 2.3 ± 0.4 % of the cross-section of RRS at 433 nm under tropospheric conditions. The contribution of VRS(O2) is also found to be in agreement with calculated scattering cross-sections. It is concluded, that this phenomenon has to be included in the spectral evaluation of weak absorbers as it

  16. Sparse-sampling with time-encoded (TICO) stimulated Raman scattering for fast image acquisition

    Science.gov (United States)

    Hakert, Hubertus; Eibl, Matthias; Karpf, Sebastian; Huber, Robert

    2017-07-01

    Modern biomedical imaging modalities aim to provide researchers a multimodal contrast for a deeper insight into a specimen under investigation. A very promising technique is stimulated Raman scattering (SRS) microscopy, which can unveil the chemical composition of a sample with a very high specificity. Although the signal intensities are enhanced manifold to achieve a faster acquisition of images if compared to standard Raman microscopy, there is a trade-off between specificity and acquisition speed. Commonly used SRS concepts either probe only very few Raman transitions as the tuning of the applied laser sources is complicated or record whole spectra with a spectrometer based setup. While the first approach is fast, it reduces the specificity and the spectrometer approach records whole spectra -with energy differences where no Raman information is present-, which limits the acquisition speed. Therefore, we present a new approach based on the TICO-Raman concept, which we call sparse-sampling. The TICO-sparse-sampling setup is fully electronically controllable and allows probing of only the characteristic peaks of a Raman spectrum instead of always acquiring a whole spectrum. By reducing the spectral points to the relevant peaks, the acquisition time can be greatly reduced compared to a uniformly, equidistantly sampled Raman spectrum while the specificity and the signal to noise ratio (SNR) are maintained. Furthermore, all laser sources are completely fiber based. The synchronized detection enables a full resolution of the Raman signal, whereas the analogue and digital balancing allows shot noise limited detection. First imaging results with polystyrene (PS) and polymethylmethacrylate (PMMA) beads confirm the advantages of TICO sparse-sampling. We achieved a pixel dwell time as low as 35 μs for an image differentiating both species. The mechanical properties of the applied voice coil stage for scanning the sample currently limits even faster acquisition.

  17. Synthesis of anti-aggregation silver nanoparticles based on inositol hexakisphosphoric micelles for a stable surface enhanced Raman scattering substrate

    International Nuclear Information System (INIS)

    Wang Na; Yang Haifeng; Zhu Xuan; Zhang Rui; Wang Yao; Huang Guanfeng; Zhang Zongrang

    2009-01-01

    We report a novel method of synthesizing a kind of silver nanoparticles aided by the inositol hexakisphosphoric micelle as a soft template and stabilizer. By controlling the reaction time, UV-vis and TEM observations of the size growth of the nanoparticles are performed. Careful examinations of surface enhanced Raman scattering (SERS) spectra of 2-mercaptopyridine (2-Mpy) on the as-produced silver nanoparticles exhibit very stable and reproducible Raman signals within about 4 months.

  18. Live-cell stimulated Raman scattering imaging of alkyne-tagged biomolecules.

    Science.gov (United States)

    Hong, Senlian; Chen, Tao; Zhu, Yuntao; Li, Ang; Huang, Yanyi; Chen, Xing

    2014-06-02

    Alkynes can be metabolically incorporated into biomolecules including nucleic acids, proteins, lipids, and glycans. In addition to the clickable chemical reactivity, alkynes possess a unique Raman scattering within the Raman-silent region of a cell. Coupling this spectroscopic signature with Raman microscopy yields a new imaging modality beyond fluorescence and label-free microscopies. The bioorthogonal Raman imaging of various biomolecules tagged with an alkyne by a state-of-the-art Raman imaging technique, stimulated Raman scattering (SRS) microscopy, is reported. This imaging method affords non-invasiveness, high sensitivity, and molecular specificity and therefore should find broad applications in live-cell imaging. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Raman spectra studies of dipeptides

    International Nuclear Information System (INIS)

    Blanchard, Simone.

    1977-10-01

    This work deals with the homogenous and heterogeneous dipeptides derived from alanine and glycine, in the solid state or in aqueous solutions, in the zwitterions or chlorhydrates form. The Raman spectra comparative study of these various forms of hydrogenated or deuterated compounds allows to specify some of the attributions which are necessary in the conformational study of the like tripeptides. These compounds contain only one peptidic group; therefore there is no possibility of intramolecular hydrogen bond which caracterise vibrations of non bonded peptidic groups and end groups. Infrared spectra of solid dipeptides will be presented and discussed in the near future [fr

  20. Two-magnon Raman scattering in LiMnPO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Calderon Filho, C.J. [Instituto de Física ”Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo (Brazil); Gomes, P.F. [Instituto de Física ”Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo (Brazil); Universidade Federal de Goiás, 75801-615, Jataí, Goiás (Brazil); García-Flores, A.F.; Barberis, G.E. [Instituto de Física ”Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo (Brazil); Granado, E., E-mail: egranado@ifi.unicamp.br [Instituto de Física ”Gleb Wataghin”, UNICAMP, 13083-859, Campinas, São Paulo (Brazil)

    2015-03-01

    Two-magnon Raman scattering is observed in the orthophosphate LiMnPO{sub 4}, carrying quantitative information on the magnetic interactions between local Mn{sup 2+} moments. A simulated annealing fitting procedure of the Raman signal to theoretical curves derived from a magnetic Hamiltonian was carried out, taking exchange and anisotropy constants as free fitting parameters. Previously reported inelastic neutron scattering (INS) data [J. Li et al., Phys. Rev. B 79, 144410 (2009)] were also used in the fit. It is shown that the combined application of INS and Raman scattering data in the fit reduces the ambiguity of the determined set of exchange parameters with respect to fitting procedures using INS or Raman data independently. The temperature dependence of the Raman signal does not show a collapse of the two-magnon excitations at the long-range magnetic ordering temperature, T{sub N}=34K, supporting significant short-range spin correlations above T{sub N}. - Highlights: • A two-magnon Raman scattering signal was observed in the orthophosphate LiMnPO{sub 4}. • Calculations under the Fleury–Loudon were carried out to simulate the observed signal. • A combined fit using Raman and neutron data yields a robust set of magnetic parameters. • The nearest-neighbor interaction is largely dominant over the remaining terms. • This work is a step forward in combining techniques to obtain exchange constants.

  1. Excited-state Raman spectroscopy with and without actinic excitation: S{sub 1} Raman spectra of trans-azobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Dobryakov, A. L.; Quick, M.; Ioffe, I. N.; Granovsky, A. A.; Ernsting, N. P.; Kovalenko, S. A. [Department of Chemistry, Humboldt-Universität zu Berlin, Brook-Taylor-Str. 2, D-12489 Berlin (Germany)

    2014-05-14

    We show that femtosecond stimulated Raman spectroscopy can record excited-state spectra in the absence of actinic excitation, if the Raman pump is in resonance with an electronic transition. The approach is illustrated by recording S{sub 1} and S{sub 0} spectra of trans-azobenzene in n-hexane. The S{sub 1} spectra were also measured conventionally, upon nπ* (S{sub 0} → S{sub 1}) actinic excitation. The results are discussed and compared to earlier reports.

  2. [Raman spectra of monkey cerebral cortex tissue].

    Science.gov (United States)

    Zhu, Ji-chun; Guo, Jian-yu; Cai, Wei-ying; Wang, Zu-geng; Sun, Zhen-rong

    2010-01-01

    Monkey cerebral cortex, an important part in the brain to control action and thought activities, is mainly composed of grey matter and nerve cell. In the present paper, the in situ Raman spectra of the cerebral cortex of the birth, teenage and aged monkeys were achieved for the first time. The results show that the Raman spectra for the different age monkey cerebral cortex exhibit most obvious changes in the regions of 1000-1400 and 2800-3000 cm(-1). With monkey growing up, the relative intensities of the Raman bands at 1313 and 2885 cm(-1) mainly assigned to CH2 chain vibrational mode of lipid become stronger and stronger whereas the relative intensities of the Raman bands at 1338 and 2932 cm(-1) mainly assigned to CH3 chain vibrational mode of protein become weaker and weaker. In addition, the two new Raman bands at 1296 and 2850 cm(-1) are only observed in the aged monkey cerebral cortex, therefore, the two bands can be considered as a character or "marker" to differentiate the caducity degree with monkey growth In order to further explore the changes, the relative intensity ratios of the Raman band at 1313 cm(-1) to that at 1338 cm(-1) and the Raman band at 2885 cm(-1) to that at 2 932 cm(-1), I1313/I1338 and I2885/I2932, which are the lipid-to-protein ratios, are introduced to denote the degree of the lipid content. The results show that the relative intensity ratios increase significantly with monkey growth, namely, the lipid content in the cerebral cortex increases greatly with monkey growth. So, the authors can deduce that the overmuch lipid is an important cause to induce the caducity. Therefore, the results will be a powerful assistance and valuable parameter to study the order of life growth and diagnose diseases.

  3. Fluid temperature measurement technique by using Raman scattering

    International Nuclear Information System (INIS)

    An, Jeong Soo; Yang, Sun Kyu; Min, Kyung Ho; Chung, Moon Ki; Choi, Young Don

    1999-06-01

    Temperature measurement technique by using Raman scattering was developed for the liquid water at temperature of 20 - 90 degree C and atmospheric pressure. Strong relationship between Raman scattering characteristics and liquid temperature change was observed. Various kinds of measurement techniques, such as Peak Intensity, Peak Wavelength, FWHM (Full Width at Half Maximum), PMCR ( Polymer Monomer Concentration RAte), TSIR (Temperature Sensitive Intensity Ratio), IDIA (Integral Difference Intensity Area) were tested. TSIR has the highest accuracy in mean error or 0.1 deg C and standard deviation of 0.1248 deg C. This report is one of the results in developing process of Raman temperature measurement technique. Next research step is to develop Raman temperature measurement technique at the high temperature and high pressure conditions in single or two phase flows. (author). 13 refs., 3 tabs., 38 figs

  4. Resonant x-ray Raman scattering from atoms and molecules

    International Nuclear Information System (INIS)

    Cowan, P.L.

    1992-01-01

    Inelastic x-ray scattering and elastic x-ray scattering are fundamentally related processes. When the x-ray photon energy is near the ionization threshold for an inner shell, the inelastic channel is dominated by resonant x-ray Raman scattering. Studies of this emission not only illuminate the resonant scattering process in general, they also point to new opportunities for spectral studies of electronic structure using x-rays. Atoms in the form of a free gas provide an ideal target for testing the current theoretical understanding of resonant x-ray Raman scattering. In addition, x-ray scattering from molecular gases demonstrates the effect of bonding symmetry on the polarization and angular distribution of the scattered x-rays. Comparisons of experimental data with theory demonstrate both the successes and limitations of simple, single-electron interpretations of the scattering process

  5. Nanostructured surface enhanced Raman scattering substrates for explosives detection

    DEFF Research Database (Denmark)

    Schmidt, Michael Stenbaek; Olsen, Jesper Kenneth; Boisen, Anja

    2010-01-01

    Here we present a method for trace detection of explosives in the gas phase using novel surface enhanced Raman scattering (SERS) spectroscopy substrates. Novel substrates that produce an exceptionally large enhancement of the Raman effect were used to amplify the Raman signal of explosives...

  6. Resonance Raman Optical Activity and Surface Enhanced Resonance Raman Optical Activity analysis of Cytochrome C

    DEFF Research Database (Denmark)

    Johannessen, Christian; Abdali, Salim; White, Peter C.

    2007-01-01

    High quality Resonance Raman (RR) and resonance Raman Optical Activity (ROA) spectra of cytochrome c were obtained in order to perform full assignment of spectral features of the resonance ROA spectrum. The resonance ROA spectrum of cytochrome c revealed a distinct spectral signature pattern due...... to resonance enhanced skeletal porphyrin vibrations, more pronounced than any contribution from the protein back-bone. Combining the intrinsic resonance enhancement of cytochrome c with surface plasmon enhancement by colloidal silver particles, the Surface Enhanced Resonance Raman Scattering (SERRS) and Chiral...... Enhanced Raman Spectroscopy (ChERS) spectra of the protein were successfully obtained at very low concentration (as low as 1 µM). The assignment of spectral features was based on the information obtained from the RR and resonance ROA spectra. Excellent agreement between RR and SERRS spectra is reported...

  7. Molecular near-field antenna effect in resonance hyper-Raman scattering: Intermolecular vibronic intensity borrowing of solvent from solute through dipole-dipole and dipole-quadrupole interactions

    Energy Technology Data Exchange (ETDEWEB)

    Shimada, Rintaro; Hamaguchi, Hiro-o, E-mail: hhama@nctu.edu.tw [Department of Applied Chemistry and Institute of Molecular Science, National Chiao Tung University, 1001 University Road, Hsinchu 30010, Taiwan (China)

    2014-05-28

    We quantitatively interpret the recently discovered intriguing phenomenon related to resonance Hyper-Raman (HR) scattering. In resonance HR spectra of all-trans-β-carotene (β-carotene) in solution, vibrations of proximate solvent molecules are observed concomitantly with the solute β-carotene HR bands. It has been shown that these solvent bands are subject to marked intensity enhancements by more than 5 orders of magnitude under the presence of β-carotene. We have called this phenomenon the molecular-near field effect. Resonance HR spectra of β-carotene in benzene, deuterated benzene, cyclohexane, and deuterated cyclohexane have been measured precisely for a quantitative analysis of this effect. The assignments of the observed peaks are made by referring to the infrared, Raman, and HR spectra of neat solvents. It has been revealed that infrared active and some Raman active vibrations are active in the HR molecular near-field effect. The observed spectra in the form of difference spectra (between benzene/deuterated benzene and cyclohexane/deuterated cyclohexane) are quantitatively analyzed on the basis of the extended vibronic theory of resonance HR scattering. The theory incorporates the coupling of excited electronic states of β-carotene with the vibrations of a proximate solvent molecule through solute–solvent dipole–dipole and dipole–quadrupole interactions. It is shown that the infrared active modes arise from the dipole–dipole interaction, whereas Raman active modes from the dipole–quadrupole interaction. It is also shown that vibrations that give strongly polarized Raman bands are weak in the HR molecular near-field effect. The observed solvent HR spectra are simulated with the help of quantum chemical calculations for various orientations and distances of a solvent molecule with respect to the solute. The observed spectra are best simulated with random orientations of the solvent molecule at an intermolecular distance of 10 Å.

  8. Resonance electronic Raman scattering in rare earth crystals

    International Nuclear Information System (INIS)

    Williams, G.M.

    1988-01-01

    The intensities of Raman scattering transitions between electronic energy levels of trivalent rare earth ions doped into transparent crystals were measured and compared to theory. A particle emphasis was placed on the examination of the effect of intermediate state resonances on the Raman scattering intensities. Two specific systems were studied: Ce 3+ (4f 1 ) in single crystals of LuPO 4 and Er 3+ (4f 11 ) in single crystals of ErPO 4 . 134 refs., 92 figs., 33 tabs

  9. Faraday effect on stimulated Raman scattering in the linear region

    Science.gov (United States)

    Liu, Z. J.; Li, B.; Xiang, J.; Cao, L. H.; Zheng, C. Y.; Hao, L.

    2018-04-01

    The paper presents the effect of Faraday rotation on stimulated Raman scattering (SRS). When light propagates along the magnetic field upon plasma, Faraday rotation occurs. The rotation angle can be expressed as {{d}}θ /{{d}}{s}=2.93× {10}-4B\\tfrac{{n}e/{n}c}{\\sqrt{1-{n}e/{n}c}} {cm}}-1 approximately, where θ is the rotation angle and s is distance, n e is the electron density, n c is the critical density and B is magnetic field in unit of Gauss. Both the incident light and Raman light have Faraday effects. The angle between the polarization directions of incident light and Raman light changes with position. The driven force of electron plasma wave also reduces, and then SRS scattering level is reduced. Faraday rotation effect can increase the laser intensity threshold of Raman scattering, even if the magnetic field strength is small. The circularly polarized light incident case is also compared with that of the linearly polarized light incident. The Raman scattering level of linearly polarized light is much smaller than that of circularly polarized light in the magnetized plasma. The difference between linearly and circularly polarized lights is also discussed.

  10. Effect of concentration and pH on the surface-enhanced Raman scattering of captopril on nano-colloidal silver surface

    Science.gov (United States)

    Gao, Junxiang; Gu, Huaimin; Liu, Fangfang; Dong, Xiao; Xie, Min; Hu, Yongjun

    2011-07-01

    In this report, Raman and surface-enhanced Raman scattering (SERS) spectra of captopril are studied in detail. Herein, the Raman bands are assigned by the density functional theory (DFT) calculations and potential energy distributions (PED) based on internal coordinates of the molecule, which are found to be in good agree with the experimental values. Furthermore, the concentration and pH dependence of the SERS intensity of the molecule is discussed. By analyzing the intensities variation of SERS bands of the different concentrations of captopril solution, it can be concluded that the molecules orientation adsorbed on the silver nanoparticles surface change with the change of the concentrations. The variation of SERS spectra of captopril with the change of pH suggests that the interaction among the adsorbates with Ag cluster depend on the protonated state of the adsorbate and the aggregation of silver nanoparticles.

  11. Resonance Raman spectra of wurtzite and zincblende CdSe nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Kelley, Anne Myers, E-mail: amkelley@ucmerced.edu [Chemistry and Chemical Biology, School of Natural Sciences, University of California, 5200 North Lake Road, Merced, CA 95343 (United States); Dai, Quanqin; Jiang, Zhong-jie; Baker, Joshua A.; Kelley, David F. [Chemistry and Chemical Biology, School of Natural Sciences, University of California, 5200 North Lake Road, Merced, CA 95343 (United States)

    2013-08-30

    Highlights: ► Very similar resonance Raman spectra of wurtzite and zincblende CdSe nanocrystals. ► First absolute resonance Raman cross-sections reported for CdSe nanocrystals. ► LO overtones suggest slightly stronger electron–phonon coupling in wurtzite form. - Abstract: Resonance Raman spectra and absolute differential Raman cross-sections have been measured for CdSe nanocrystals in both the wurtzite and zincblende crystal forms at four excitation wavelengths from 457.9 to 514.5 nm. The frequency and bandshape of the longitudinal optical (LO) phonon fundamental is essentially identical for both crystal forms at each excitation wavelength. The LO phonon overtone to fundamental intensity ratio appears to be slightly higher for the wurtzite form, which may suggest slightly stronger exciton–phonon coupling from the Fröhlich mechanism in the wurtzite form. The LO fundamental Raman cross-sections are very similar for both crystal forms at each excitation wavelength.

  12. Gain reduction measurements in transient stimulated Raman scattering

    NARCIS (Netherlands)

    Heeman, R.J.; Godfried, H.P

    1995-01-01

    Threshold energy measurements of transient rotational stimulated Raman scattering are compared to Raman conversion calculations from semiclassical theories using a simple concept of a gain reduction factor which expresses the reduction of the gain from its steady-state value due to transient

  13. Electron Raman scattering in semiconductor quantum wire in external magnetic field: Froehlich interaction

    International Nuclear Information System (INIS)

    Betancourt-Riera, Ri.; Nieto Jalil, J.M.; Betancourt-Riera, Re.; Riera, R.

    2009-01-01

    The differential cross-section for an electron Raman scattering process in a semiconductor quantum wire in the presence of an external magnetic field perpendicular to the plane of confinement regarding phonon-assisted transitions, is calculated. We assume single parabolic conduction band and present a description of the phonon modes of cylindrical structures embedded in another material using the Froehlich phonon interaction. To illustrate the theory we use a GaAs/Al 0.35 Ga 0.75 As system. The emission spectra are discussed for different scattering configurations and the selection rules for the processes are also studied. The magnetic field distribution is considered constant with value B 0 inside of the wire, and zero outside.

  14. Determination of Temperature-Dependent Stress State in Thin AlGaN Layer of AlGaN/GaN HEMT Heterostructures by Near-Resonant Raman Scattering

    Directory of Open Access Journals (Sweden)

    Yanli Liu

    2015-01-01

    Full Text Available The temperature-dependent stress state in the AlGaN barrier layer of AlGaN/GaN heterostructure grown on sapphire substrate was investigated by ultraviolet (UV near-resonant Raman scattering. Strong scattering peak resulting from the A1(LO phonon mode of AlGaN is observed under near-resonance condition, which allows for the accurate measurement of Raman shifts with temperature. The temperature-dependent stress in the AlGaN layer determined by the resonance Raman spectra is consistent with the theoretical calculation result, taking lattice mismatch and thermal mismatch into account together. This good agreement indicates that the UV near-resonant Raman scattering can be a direct and effective method to characterize the stress state in thin AlGaN barrier layer of AlGaN/GaN HEMT heterostructures.

  15. Raman scattering and band-gap variations of Al-doped ZnO nanoparticles synthesized by a chemical colloid process

    International Nuclear Information System (INIS)

    Lo, Shih-Shou; Huang, Dison; Tu, Chun Hsiang; Hou, Chia-Hung; Chen, Chii-Chang

    2009-01-01

    This study synthesizes Al-doped ZnO (AZO) nanoparticles using a chemical colloid process. Raman scattering analysis shows that Al doping increases the lattice defects and induces Raman vibration modes of 651 cm -1 . The Raman shift of the active mode E 2 (high) of AZO nanoparticles shows the presence and increase in the stress in nanoparticles when the Al dopant concentration increases. Room-temperature photoluminescence (RT-PL) spectra of synthesized AZO nanoparticles exhibit strong UV emissions near the band edges. The RT-PL peak shifts to a higher photon energy region as the Al concentration increases, indicating a broadening of the band gap.

  16. Enhanced light scattering of the forbidden longitudinal optical phonon mode studied by micro-Raman spectroscopy on single InN nanowires

    International Nuclear Information System (INIS)

    Schaefer-Nolte, E O; Stoica, T; Gotschke, T; Limbach, F A; Gruetzmacher, D; Calarco, R; Sutter, E; Sutter, P

    2010-01-01

    In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E 2 phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

  17. Enhanced Light Scattering of the Forbidden longitudinal Optical Phonon Mode Studied by Micro-Raman Spectroscopy on Single InN nanowires

    International Nuclear Information System (INIS)

    Sutter, E.; Schafer-Nolte, E.O.; Stoica, T.; Gotschke, T.; Limbach, F.A.; Sutter, P.; Grutzmacher, D.; Calarco, R.

    2010-01-01

    In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E2 phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

  18. Enhanced light scattering of the forbidden longitudinal optical phonon mode studied by micro-Raman spectroscopy on single InN nanowires.

    Science.gov (United States)

    Schäfer-Nolte, E O; Stoica, T; Gotschke, T; Limbach, F A; Sutter, E; Sutter, P; Grützmacher, D; Calarco, R

    2010-08-06

    In the literature, there are controversies on the interpretation of the appearance in InN Raman spectra of a strong scattering peak in the energy region of the unscreened longitudinal optical (LO) phonons, although a shift caused by the phonon-plasmon interaction is expected for the high conductance observed in this material. Most measurements on light scattering are performed on ensembles of InN nanowires (NWs). However, it is important to investigate the behavior of individual nanowires and here we report on micro-Raman measurements on single nanowires. When changing the polarization direction of the incident light from parallel to perpendicular to the wire, the expected reduction of the Raman scattering was observed for transversal optical (TO) and E(2) phonon scattering modes, while a strong symmetry-forbidden LO mode was observed independently on the laser polarization direction. Single Mg- and Si-doped crystalline InN nanowires were also investigated. Magnesium doping results in a sharpening of the Raman peaks, while silicon doping leads to an asymmetric broadening of the LO peak. The results can be explained based on the influence of the high electron concentration with a strong contribution of the surface accumulation layer and the associated internal electric field.

  19. Polarization Sensitive Coherent Raman Measurements of DCVJ

    Science.gov (United States)

    Anderson, Josiah; Cooper, Nathan; Lawhead, Carlos; Shiver, Tegan; Ujj, Laszlo

    2014-03-01

    Coherent Raman spectroscopy which recently developed into coherent Raman microscopy has been used to produce label free imaging of thin layers of material and find the spatial distributions of certain chemicals within samples, e.g. cancer cells.(1) Not all aspects of coherent scattering have been used for imaging. Among those for example are special polarization sensitive measurements. Therefore we have investigated the properties of polarization sensitive CARS spectra of a highly fluorescent molecule, DCVJ.(2) Spectra has been recorded by using parallel polarized and perpendicular polarized excitations. A special polarization arrangement was developed to suppress the non-resonant background scattering from the sample. These results can be used to improve the imaging properties of a coherent Raman microscope in the future. This is the first time coherent Raman polarization sensitive measurements have been used to characterize the vibrational modes of DCVJ. 1: K. I. Gutkowski, et al., ``Fluorescence of dicyanovinyl julolidine in a room temperature ionic liquid '' Chemical Physics Letters 426 (2006) 329 - 333 2: Fouad El-Diasty, ``Coherent anti-Stokes Raman scattering: Spectroscopy and microscopy'' Vibrational Spectroscopy 55 (2011) 1-37

  20. Coherent anti-Stokes Raman scattering spectroscope/microscope based on a widely tunable laser source

    Science.gov (United States)

    Dementjev, A.; Gulbinas, V.; Serbenta, A.; Kaucikas, M.; Niaura, G.

    2010-03-01

    We present a coherent anti-Stokes Raman scattering (CARS) microscope based on a robust and simple laser source. A picosecond laser operating in a cavity dumping regime at the 1 MHz repetition rate was used to pump a traveling wave optical parametric generator, which serves as a two-color excitation light source for the CARS microscope. We demonstrate the ability of the presented CARS microscope to measure CARS spectra and images by using several detection schemes.

  1. Overview of the use of theory to understand infrared and Raman spectra and images of biomolecules: colorectal cancer as an example

    DEFF Research Database (Denmark)

    Piva, J. A. A. C.; Silva, J. L. R.; Raniero, L.

    2011-01-01

    In this work, we present the state of the art in the use of theory (first principles, molecular dynamics, and statistical methods) for interpreting and understanding the infrared (vibrational) absorption and Raman scattering spectra. It is discussed how they can be used in combination with purely...... of biomolecules are very sensitive to their environment and aggregation state, the combined use of infrared and Raman spectroscopy and imaging and theoretical simulations are clearly fields, which can benefit from their joint and mutual development....

  2. Carbon nanotubes doped with trivalent elements by using back - scattering Raman spectroscopy

    Directory of Open Access Journals (Sweden)

    S. A. Babanejad

    2008-12-01

    Full Text Available  In this paper by using DC arc discharge method and acetylene gas, as the carbon source, and nitrogen, as the carrier gas, canrbon nanotubes, CNTs, doped with trivalent element boron, B, have been produced. The deposited CNTs on the cathod electrod, which have structural doped properties to boron element, have been collected and after purification have been investigated by back-scattering Raman spectroscopy. The results reveal that the high frequency G mode component in CNTs doped with electron acceptor element, B, shift to higher wavenumbers. The low frequency G mode component which can appear at approximately 1540–1570 cm-1 wavenumber region, called BWF mode, is a sign of metallic CNT. In the synthesized doped CNTs due to the presence of boron dopant, D mode has sharp peaks and has relatively high intensity in the Raman spectra .

  3. Retrieval method of aerosol extinction coefficient profile based on backscattering, side-scattering and Raman-scattering lidar

    Science.gov (United States)

    Shan, Huihui; Zhang, Hui; Liu, Junjian; Tao, Zongming; Wang, Shenhao; Ma, Xiaomin; Zhou, Pucheng; Yao, Ling; Liu, Dong; Xie, Chenbo; Wang, Yingjian

    2018-03-01

    Aerosol extinction coefficient profile is an essential parameter for atmospheric radiation model. It is difficult to get higher signal to noise ratio (SNR) of backscattering lidar from the ground to the tropopause especially in near range. Higher SNR problem can be solved by combining side-scattering and backscattering lidar. Using Raman-scattering lidar, aerosol extinction to backscatter ratio (lidar ratio) can be got. Based on side-scattering, backscattering and Raman-scattering lidar system, aerosol extinction coefficient is retrieved precisely from the earth's surface to the tropopause. Case studies show this method is reasonable and feasible.

  4. Enhanced Raman scattering in porous silicon grating.

    Science.gov (United States)

    Wang, Jiajia; Jia, Zhenhong; Lv, Changwu

    2018-03-19

    The enhancement of Raman signal on monocrystalline silicon gratings with varying groove depths and on porous silicon grating were studied for a highly sensitive surface enhanced Raman scattering (SERS) response. In the experiment conducted, porous silicon gratings were fabricated. Silver nanoparticles (Ag NPs) were then deposited on the porous silicon grating to enhance the Raman signal of the detective objects. Results show that the enhancement of Raman signal on silicon grating improved when groove depth increased. The enhanced performance of Raman signal on porous silicon grating was also further improved. The Rhodamine SERS response based on Ag NPs/ porous silicon grating substrates was enhanced relative to the SERS response on Ag NPs/ porous silicon substrates. Ag NPs / porous silicon grating SERS substrate system achieved a highly sensitive SERS response due to the coupling of various Raman enhancement factors.

  5. Surface-Enhanced Raman Scattering Nanoparticles as Optical Labels for Imaging Cell Surface Proteins

    Science.gov (United States)

    MacLaughlin, Christina M.

    Assaying the expression of cell surface proteins has widespread application for characterizing cell type, developmental stage, and monitoring disease transformation. Immunophenotyping is conducted by treating cells with labelled targeting moieties that have high affinity for relevant surface protein(s). The sensitivity and specificity of immunophenotyping is defined by the choice of contrast agent and therefore, the number of resolvable signals that can be used to simultaneously label cells. Narrow band width surface-enhanced Raman scattering (SERS) nanoparticles are proposed as optical labels for multiplexed immunophenotying. Two types of surface coatings were investigated to passivate the gold nanoparticles, incorporate SERS functionality, and to facilitate attachment of targeting antibodies. Thiolated poly(ethylene glycol) forms dative bonds with the gold surface and is compatible with multiple physisorbed Raman-active reporter molecules. Ternary lipid bilayers are used to encapsulate the gold nanoparticles particles, and incorporate three different classes of Raman reporters. TEM, UV-Visible absorbance spectroscopy, DLS, and electrophoretic light scattering were used characterize the particle coating. Colourimetric protein assay, and secondary antibody labelling were used to quantify the antibody conjugation. Three different in vitromodels were used to investigate the binding efficacy and specificity of SERS labels for their biomarker targets. Primary human CLL cells, LY10 B lymphoma, and A549 adenocarcinoma lines were targeted. Dark field imaging was used to visualize the colocalization of SERS labels with cells, and evidence of receptor clustering was obtained based on colour shifts of the particles' Rayleigh scattering. Widefield, and spatially-resolved Raman spectra were used to detect labels singly, and in combination from labelled cells. Fluorescence flow cytometry was used to test the particles' binding specificity, and SERS from labelled cells was also

  6. The Nanofabrication and Application of Substrates for Surface-Enhanced Raman Scattering

    Directory of Open Access Journals (Sweden)

    Xian Zhang

    2012-01-01

    Full Text Available Surface-enhanced Raman scattering (SERS was discovered in 1974 and impacted Raman spectroscopy and surface science. Although SERS has not been developed to be an applicable detection tool so far, nanotechnology has promoted its development in recent decades. The traditional SERS substrates, such as silver electrode, metal island film, and silver colloid, cannot be applied because of their enhancement factor or stability, but newly developed substrates, such as electrochemical deposition surface, Ag porous film, and surface-confined colloids, have better sensitivity and stability. Surface enhanced Raman scattering is applied in other fields such as detection of chemical pollutant, biomolecules, DNA, bacteria, and so forth. In this paper, the development of nanofabrication and application of surface-enhanced Ramans scattering substrate are discussed.

  7. Anomalous Polarized Raman Scattering and Large Circular Intensity Differential in Layered Triclinic ReS2.

    Science.gov (United States)

    Zhang, Shishu; Mao, Nannan; Zhang, Na; Wu, Juanxia; Tong, Lianming; Zhang, Jin

    2017-10-24

    The Raman tensor of a crystal is the derivative of its polarizability tensor and is dependent on the symmetries of the crystal and the Raman-active vibrational mode. The intensity of a particular mode is determined by the Raman selection rule, which involves the Raman tensor and the polarization configurations. For anisotropic two-dimensional (2D) layered crystals, polarized Raman scattering has been used to reveal the crystalline orientations. However, due to its complicated Raman tensors and optical birefringence, the polarized Raman scattering of triclinic 2D crystals has not been well studied yet. Herein, we report the anomalous polarized Raman scattering of 2D layered triclinic rhenium disulfide (ReS 2 ) and show a large circular intensity differential (CID) of Raman scattering in ReS 2 of different thicknesses. The origin of CID and the anomalous behavior in polarized Raman scattering were attributed to the appearance of nonzero off-diagonal Raman tensor elements and the phase factor owing to optical birefringence. This can provide a method to identify the vertical orientation of triclinic layered materials. These findings may help to further understand the Raman scattering process in 2D materials of low symmetry and may indicate important applications in chiral recognition by using 2D materials.

  8. Analytic calculations of hyper-Raman spectra from density functional theory hyperpolarizability gradients

    Energy Technology Data Exchange (ETDEWEB)

    Ringholm, Magnus; Ruud, Kenneth [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø – The Arctic University of Norway, 9037 Tromsø (Norway); Bast, Radovan [Theoretical Chemistry and Biology, School of Biotechnology, Royal Institute of Technology, AlbaNova University Center, S-10691 Stockholm (Sweden); PDC Center for High Performance Computing, Royal Institute of Technology, S-10044 Stockholm (Sweden); Oggioni, Luca [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Tromsø – The Arctic University of Norway, 9037 Tromsø (Norway); Department of Physics G. Occhialini, University of Milano Bicocca, Piazza della scienza 3, 20126 Milan (Italy); Ekström, Ulf [Centre for Theoretical and Computational Chemistry, Department of Chemistry, University of Oslo, P.O. Box 1033 Blindern, 0315 Oslo (Norway)

    2014-10-07

    We present the first analytic calculations of the geometrical gradients of the first hyperpolarizability tensors at the density-functional theory (DFT) level. We use the analytically calculated hyperpolarizability gradients to explore the importance of electron correlation effects, as described by DFT, on hyper-Raman spectra. In particular, we calculate the hyper-Raman spectra of the all-trans and 11-cis isomers of retinal at the Hartree-Fock (HF) and density-functional levels of theory, also allowing us to explore the sensitivity of the hyper-Raman spectra on the geometrical characteristics of these structurally related molecules. We show that the HF results, using B3LYP-calculated vibrational frequencies and force fields, reproduce the experimental data for all-trans-retinal well, and that electron correlation effects are of minor importance for the hyper-Raman intensities.

  9. Raman spectra of zinc phthalocyanine monolayers absorbed on glassy carbon and gold electrodes by application of a confocal Raman microspectrometer

    NARCIS (Netherlands)

    Palys-Staron, B.J.; Palys, B.J.; Puppels, G.J.; Puppels, G.J.; van den Ham, D.M.W.; van den Ham, D.M.W.; Feil, D.; Feil, D.

    1992-01-01

    Raman spectra of zinc phthalocyanine monolayers, adsorbed on gold and on glassy carbon surfaces (electrodes), are presented. These spectra have been recorded with the electrodes inside and outside an electrochemical cell filled with an aqueous electrolyte. A confocal Raman microspectrometer was

  10. Electromagnetic study of surface enhanced Raman scattering of plasmonic-biomolecule: An interaction between nanodimer and single biomolecule

    Science.gov (United States)

    Pandey, Gyanendra Krishna; Pathak, Nilesh Kumar; Uma, R.; Sharma, R. P.

    2017-04-01

    In this article we have investigated the electromagnetic surface enhanced Raman scattering (SERS) of single biomolecule adsorbed at the surface of spherical nanodimer. The SERS mechanism has been studied using first principle approach for spherical nanodimer geometry. The coupling of plasmonic concept to biomolecule results the broadband tunable enhancement in Raman gain factor. In this observation the enhancement factor was observed around ≈ 1015. The plasmonic properties of metal nanodimer are analysed in terms of surface plasmon resonances, extinction efficiency and polarisability that have been derived under quasistatic approximation. In this paper, various facets like interdipole separation, molecule distance and size of the plasmonic nanogeometry are taken into account to analyse the Raman gain factor. We also observe that the frequency range expands sufficiently which increases the broad detectability range of the molecule which generates signal even in the outside of Raman range i.e. in between IR to UV region. Lastly, the extinction spectra and electric field profile have been evaluated at resonance wavelength 364 nm. The comparison between electrostatic approach and numerical approach (using DDA) has also been done in terms of extinction spectra.

  11. Second-order Raman spectra of LiHxD1-x crystals

    International Nuclear Information System (INIS)

    Plekhanov, V.G.

    1994-01-01

    High-resolution Raman spectra of LiH x D 1-x cubic crystals were measured for the first time in a wide concentration range (0≤x≤1) at room temperature. The results agree well with data on inelastic neutron scattering and direct calculations of the lattice dynamics for LiH and LiD crystals. This allows one to assign the observed spectral features to the phonon excitations in X-, W-, L-, and K-points of the Brillouin zone. Spectra of LiD exhibit the high-frequency maximum with a pronounced doubled structure. This fact and the dependence of the maximum intensity on the excitation laser frequency provide clear evidence that the maximum is due to excitation of LO(Γ)-phonons in pure or mixed crystals. In the x approx-lt 0.4 range, the LO-phonons manifest themselves in the spectra of both pure LiD and mixed LiH x D 1-x crystals, which demonstrates for the first time their two-mode character in this concentration range. This conclusion is in contradiction with predictions of the coherent potential model. In this paper, causes of this conflict are briefly discussed. 36 refs., 5 figs., 2 tabs

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  13. Structural characterization of tellurite glasses doped with transition metal oxides using Raman spectra and ab initio calculations.

    Science.gov (United States)

    Mohamed, Tarek A; Shaltout, I; Al Yahyaei, K M

    2006-05-01

    Systems of iron tellurite glasses were prepared by melt quenching with compositions of [85%TeO2+5%Fe2O3+10%TMO], where transition metal oxides (TMO) are TiO2, V2O5, MnO, CoO, NiO and CuO. Furthermore, the main structural units of these samples have been characterized by means of Raman spectra (150-1200 cm(-1)) as well as wavenumber predictions by means of Gaussian 98 ab initio calculations for the proposed site symmetries of TeO4(4-) triagonal bipyramid (C2v) and Te2O7(6-) bridged tetrahedra (Cs and C1). Aided by normal coordinate analysis, calculated vibrational frequencies, Raman scattering activities, force constants in internal coordinates and potential energy distributions (PEDs), revised vibrational assignments for the fundamental modes have been proposed. The main structural features are correlated to the dominant units of triagonal bipyramid (tbp) or bridged tetrahedral (TeO3+1 binds to TeO3 through TeOTe bridge; corner sharing). Moreover, the Raman spectra of the investigated tellurites reflect a structural change from tbp (coordination number is four) to triagonal pyramidal (coordination number is three).

  14. Effect of surface density silver nanoplate films toward surface-enhanced Raman scattering enhancement for bisphenol A detection

    Science.gov (United States)

    Bakar, N. A.; Salleh, M. M.; Umar, A. A.; Shapter, J. G.

    2018-03-01

    This paper reports a study on surface-enhanced Raman scattering (SERS) phenomenon of triangular silver nanoplate (NP) films towards bisphenol A (BPA) detection. The NP films were prepared using self-assembly technique with four different immersion times; 1 hour, 2 hours, 5 hours, and 8 hours. The SERS measurement was studied by observing the changes in Raman spectra of BPA after BPA absorbed on the NP films. It was found that the Raman intensity of BPA peaks was enhanced by using the prepared SERS substrates. This is clearly indicated that these SERS silver substrates are suitable to sense industrial chemical and potentially used as SERS detector. However, the rate of SERS enhancement is depended on the distribution of NP on the substrate surface.

  15. Abnormal anti-Stokes Raman emission as a coherent anti-Stokes Raman scattering-like process in disordered media

    International Nuclear Information System (INIS)

    Baltog, Ioan; Baibarac, Mihaela; Smaranda, Ion; Lefrant, Serge

    2011-01-01

    In this paper, we demonstrate that, by continuous single beam excitation, one can generate an abnormal anti-Stokes Raman emission (AASRE) whose properties are similar to a coherent anti-Stokes Raman scattering (CARS). The effect has been observed in materials which possess intrinsically nonlinear properties (LiNbO 3 and CdS), which have the electric susceptibility of third order different from zero, χ (3) ≠ 0, as well as in materials that become nonlinear under resonant optical excitation. In the latter case, we used poly-3,4-ethylendioxythiophene (PEDOT) in its undoped state deposited electrochemically on Au support. Raman studies corroborated with images of optical microscopy demonstrate that the production of AASRE is conditioned by the existence of a particular morphology of the sample able to ensure efficient transport of the light inside the sample through a multiple light scattering mechanism. In this context, it was found that LiNbO 3 and CdS in powder form as well as the PEDOT films layered on a rough Au substrate are suitable morphological forms. We explain AASRE as resulting from a wave-mixing mechanism of the incident laser light ω l with a Stokes-shifted Raman light ω S produced by a spontaneous Raman light scattering process, both strongly scattered inside the sample. As a CARS process, AASRE is conditioned by the achievement of phase-matching requirements, which makes the difference between the wave vectors of mixing light close to zero, Δk =/2k l - k S - k CARS /∼ 0. In condensed media, the small dispersion of the refractive index makes Δk ∼ 0 so that the formation of a favourable phase-matching geometry may be accomplished even at a crossing angle θ of travelling scattered light ω l and ω S . For tightly focused beams, the requirement of phase matching relaxes; it is no longer sensitive to the Raman shift, so that a wide intense anti-Stokes Raman spectrum is observed at an angle larger than the Stokes Raman spectrum.

  16. UV Resonant Raman Spectrometer with Multi-Line Laser Excitation

    Science.gov (United States)

    Lambert, James L.; Kohel, James M.; Kirby, James P.; Morookian, John Michael; Pelletier, Michael J.

    2013-01-01

    A Raman spectrometer employs two or more UV (ultraviolet) laser wavel engths to generate UV resonant Raman (UVRR) spectra in organic sampl es. Resonant Raman scattering results when the laser excitation is n ear an electronic transition of a molecule, and the enhancement of R aman signals can be several orders of magnitude. In addition, the Ra man cross-section is inversely proportional to the fourth power of t he wavelength, so the UV Raman emission is increased by another fact or of 16, or greater, over visible Raman emissions. The Raman-scatter ed light is collected using a high-resolution broadband spectrograph . Further suppression of the Rayleigh-scattered laser light is provi ded by custom UV notch filters.

  17. Preliminary investigation of an atmospheric microplasma using Raman and Thomson laser scattering

    Science.gov (United States)

    Sommers, Bradley; Adams, Steven

    2014-10-01

    A triple grating spectrometer system has been coupled with an ultraviolet laser at 266 nm for the purpose of investigating Rayleigh, Raman, and Thomson scattering within atmospheric plasma sources. Such laser interactions present a non-invasive diagnostic to investigate small scale atmospheric plasma sources, which have recently garnered interest for applications in remote optical sensing, materials processing, and environmental decontamination. In this work, the laser scatter and temperature relationship were calibrated with a heated nitrogen cell held at atmospheric pressure while subsequent scattering measurements were made in atmospheric discharges composed of nitrogen and air. An adjustable electrode configuration and dc circuit were assembled to produce a microdischarge operating in normal glow mode, thus providing a non-thermal plasma in which the translational, rotational, vibrational and electron temperatures are not in equilibrium. Preliminary results include measurements of these temperatures, which were calculated by fitting simulated scattering spectra to the experimental data obtained using the triple grating spectrometer. Measured temperatures were also compared with those obtained using standard optical emission spectroscopy methods. Special thanks to the NRC Research Associateship Program.

  18. Resonance effects in Raman scattering of quantum dots formed by the Langmuir-Blodgett method

    Energy Technology Data Exchange (ETDEWEB)

    Milekhin, A G; Sveshnikova, L L; Duda, T A [Institute of Semiconductor Physics, Lavrentjev av.13, 630090, Novosibirsk (Russian Federation); Surovtsev, N V; Adichtchev, S V [Institute of Automation and Electrometry, Koptyug av.1, 630090, Novosibirsk (Russian Federation); Azhniuk, Yu M [Institute of Electron Physics, Universytetska Str. 21, 88017, Uzhhorod (Ukraine); Himcinschi, C [Institut fuer Theoretische Physik, TU Bergakademie Freiberg, Leipziger Str. 23, 09596, Freiberg (Germany); Kehr, M; Zahn, D R T, E-mail: milekhin@thermo.isp.nsc.r [Semiconductor Physics, Chemnitz University of Technology, Chemnitz (Germany)

    2010-09-01

    The enhancement of Raman scattering by optical phonon modes in quantum dots was achieved in resonant and surface-enhanced Raman scattering experiments by approaching the laser energy to the energy of either the interband transitions or the localized surface plasmons in silver nanoclusters deposited onto the nanostructures. Resonant Raman scattering by TO, LO, and SO phonons as well as their overtones was observed for PbS, ZnS, and ZnO quantum dots while enhancement for LO and SO modes in CdS quantum dots with a factor of about 700 was measured in surface enhanced Raman scattering experiments. Multiple phonon Raman scattering observed up to 5th and 7th order for CdS and ZnO, respectively, confirms the high crystalline quality of the grown QDs.

  19. Controlling Stimulated Brillouin/Raman Scattering in High Power Fiber Lasers

    Science.gov (United States)

    2017-08-09

    AFRL-RD-PS- AFRL-RD-PS- TR-2017-0043 TR-2017-0043 CONTROLLING STIMULATED BRILLOUIN/RAMAN SCATTERING IN HIGH POWER FIBER LASERS Cody Mart Ben...average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed...unlimited. 13. SUPPLEMENTARY NOTES 14. ABSTRACT This research addressed suppression of stimulated Brillouin/Raman scattering in high power fiber lasers

  20. RAMAN LIGHT SCATTERING IN PSEUDOSPIN-ELECTRON MODEL AT STRONG PSEUDOSPIN-ELECTRON INTERACTION

    Directory of Open Access Journals (Sweden)

    T.S.Mysakovych

    2004-01-01

    Full Text Available Anharmonic phonon contributions to Raman scattering in locally anharmonic crystal systems in the framework of the pseudospin-electron model with tunneling splitting of levels are investigated. The case of strong pseudospin-electron coupling is considered. Pseudospin and electron contributions to scattering are taken into account. Frequency dependences of Raman scattering intensity for different values of model parameters and for different polarization of scattering and incident light are investigated.

  1. FT-Raman, FT-IR spectra and total energy distribution of 3-pentyl-2,6-diphenylpiperidin-4-one: DFT method.

    Science.gov (United States)

    Subashchandrabose, S; Saleem, H; Erdogdu, Y; Rajarajan, G; Thanikachalam, V

    2011-11-01

    FT-Raman and FT-IR spectra were recorded for 3-pentyl-2,6-diphenylpiperidin-4-one (PDPO) sample in solid state. The equilibrium geometries, harmonic vibrational frequencies, infrared and the Raman scattering intensities were computed using DFT/6-31G(d,p) level. Results obtained at this level of theory were used for a detailed interpretation of the infrared and Raman spectra, based on the total energy distribution (TED) of the normal modes. Molecular parameters such as bond lengths, bond angles and dihedral angles were calculated and compared with X-ray diffraction data. This comparison was good agreement. The intra-molecular charge transfer was calculated by means of natural bond orbital analysis (NBO). Hyperconjugative interaction energy was more during the π-π* transition. Energy gap of the molecule was found using HOMO and LUMO calculation, hence the less band gap, which seems to be more stable. Atomic charges of the carbon, nitrogen and oxygen were calculated using same level of calculation. Copyright © 2011 Elsevier B.V. All rights reserved.

  2. Quantum statistics of stimulated Raman and hyper-Raman scattering by master equation approach

    International Nuclear Information System (INIS)

    Gupta, P.S.; Dash, J.

    1991-01-01

    A quantum theoretical density matrix formalism of stimulated Raman and hyper-Raman scattering using master equation approach is presented. The atomic system is described by two energy levels. The effects of upper level population and the cavity loss are incorporated. The photon statistics, coherence characteristics and the building up of the Stokes field are investigated. (author). 8 figs., 5 refs

  3. Infrared absorption and Raman scattering spectroscopic studies of condensed ions

    International Nuclear Information System (INIS)

    Dao, N.Q.; Knidiri, M.

    1975-01-01

    Infrared and Raman spectra of the complex K 5 (UO 2 ) 2 F 9 were recorded in the region 4000 to 80 cm -1 . Factor group analysis was used to classify the internal vibrations of the binuclear ion (UO 2 ) 2 F 9 5- . Infrared and Raman spectra were assigned and splitting of the internal modes of the (UO 2 ) 2 F 9 5- anion interpreted. (author)

  4. 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.

  5. Stimulated Raman scattering: old physics, new applications.

    Science.gov (United States)

    Yakovlev, Vladislav V; Petrov, Georgi I; Zhang, Hao F; Noojin, Gary D; Denton, Michael L; Thomas, Robert J; Scully, Marlan O

    2009-10-01

    Stimulated Raman scattering as a promising way of expanding the tunability of ultrafast lasers and as an exciting new biomedical imaging modality capable of selective excitation and chemically-specific diagnostics of molecular species.

  6. Raman spectra of ordinary and deuterated liquid ammonias; Spectres Raman des ammoniacs ordinaire et deuteries liquides

    Energy Technology Data Exchange (ETDEWEB)

    Ceccaldi, M; Leicknam, J P [Commissariat a l' Energie Atomique, 91 - Saclay (France). Centre d' Etudes Nucleaires, direction des materiaux et des combustibles nucleaires, departement de physico-chimie, service des isotopes stables, service de spectrometrie de masse

    1968-12-01

    The three deuterated ammonia molecules, as well as ordinary ammonia, have been examined in the liquid state by Raman spectroscopy using a high-pressure cell described elsewhere. This work thus completes the infrared spectrometry studies. We have examined the NH and ND valency absorption regions. The polarization measurements and isotope effect considerations make it possible to confirm most of the attributions recently proposed for interpreting the infrared spectra of the four isotopic molecules: the apparent disagreement between the NH{sub 3} and ND{sub 3} spectra obtained in this region by infrared and Raman spectroscopy is discussed: by the first technique the number of bands in the spectra corresponds well to the theoretically expected number, and the relative intensities conform more or less to expectations; the Raman spectra however have a strong supplementary band in the same region, produced by a Fermi resonance; it is possible to explain, from theoretical considerations, why this resonance appears so easily in the Raman spectrum, whereas it is detected in the infrared only by a very detailed analysis of the effects of solvents on the ammonia. (authors) [French] Les trois ammoniacs deuteries, ainsi que l'ammoniac ordinaire, sont examines a l'etat liquide par spectrometrie Raman, a l'aide d'une cuve haute pression decrite par ailleurs. Ce travail complete donc les etudes effectuees par spectrometrie infra-rouge. Nous avons examine les regions d'absorption de valence NH et ND. Les mesures de polarisation et des considerations sur les effets isotopiques permettent de confirmer la plupart des attributions proposees recemment pour interpreter les spectres infra-rouges des quatre molecules isotopiques: on discute egalement l'apparent desaccord entre les spectres de NH{sub 3} et de ND{sub 3} obtenus dans cette region par infra-rouge et Raman: par la premiere technique le nombre de bandes relevees sur les spectres correspond bien au nombre theoriquement attendu et

  7. Analysis of soda-lime glasses using non-negative matrix factor deconvolution of Raman spectra

    OpenAIRE

    Woelffel , William; Claireaux , Corinne; Toplis , Michael J.; Burov , Ekaterina; Barthel , Etienne; Shukla , Abhay; Biscaras , Johan; Chopinet , Marie-Hélène; Gouillart , Emmanuelle

    2015-01-01

    International audience; Novel statistical analysis and machine learning algorithms are proposed for the deconvolution and interpretation of Raman spectra of silicate glasses in the Na 2 O-CaO-SiO 2 system. Raman spectra are acquired along diffusion profiles of three pairs of glasses centered around an average composition of 69. 9 wt. % SiO 2 , 12. 7 wt. % CaO , 16. 8 wt. % Na 2 O. The shape changes of the Raman spectra across the compositional domain are analyzed using a combination of princi...

  8. Comparative study of the two-phonon Raman bands of silicene and graphene

    International Nuclear Information System (INIS)

    Popov, Valentin N; Lambin, Philippe

    2016-01-01

    We present a computational study of the two-phonon Raman spectra of silicene and graphene within a density-functional non-orthogonal tight-binding model. Due to the presence of linear bands close to the Fermi energy in the electronic structure of both structures, the Raman scattering by phonons is resonant. We find that the Raman spectra exhibit a crossover behavior for laser excitation close to the π-plasmon energy. This phenomenon is explained by the disappearance of certain paths for resonant Raman scattering and the appearance of other paths beyond this energy. Besides that, the electronic joint density of states (DOS) is divergent at this energy, which is reflected on the behavior of the Raman bands of the two structures in a qualitatively different way. Additionally, a number of Raman bands, originating from divergent phonon DOS at the M point and at points, inside the Brillouin zone, is also predicted. The calculated spectra for graphene are in excellent agreement with available experimental data. The obtained Raman bands can be used for structural characterization of silicene and graphene samples by Raman spectroscopy. (paper)

  9. Raman scattering study of the a-GeTe structure and possible mechanism for the amorphous to crystal transition

    International Nuclear Information System (INIS)

    Andrikopoulos, K S; Yannopoulos, S N; Voyiatzis, G A; Kolobov, A V; Ribes, M; Tominaga, J

    2006-01-01

    We report on an inelastic (Raman) light scattering study of the local structure of amorphous GeTe (a-GeTe) films. A detailed analysis of the temperature-reduced Raman spectra has shown that appreciable structural changes occur as a function of temperature. These changes involve modifications of atomic arrangements such as to facilitate the rapid amorphous to crystal transformation, which is the major advantage of phase-change materials used in optical data storage media. A particular structural model, supported by polarization analysis, is proposed which is compatible with the experimental data as regards both the structure of a-GeTe and the crystallization transition. The remarkable difference between the Raman spectrum of the crystal and the glass can thus naturally be accounted for

  10. Quantum Zeno effect in Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Thun, K.; Peřina, Jan; Křepelka, Jaromír

    2002-01-01

    Roč. 299, - (2002), s. 19-30 ISSN 0375-9601 R&D Projects: GA MŠk LN00A015 Institutional research plan: CEZ:AV0Z1010921 Keywords : quantum measurement * Raman scattering * Zeno effect Subject RIV: BH - Optics, Masers, Lasers Impact factor: 1.483, year: 2002

  11. 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.

  12. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu2(Fe,Zn)SnS4

    International Nuclear Information System (INIS)

    Fontané, X.; Izquierdo-Roca, V.; Saucedo, E.; Schorr, S.; Yukhymchuk, V.O.; Valakh, M.Ya.; Pérez-Rodríguez, A.; Morante, J.R.

    2012-01-01

    Highlights: ► Analysis of main and weaker Raman peaks from Cu 2 FeZnS 4 and Cu 2 ZnSnS 4 compounds. ► Identification of a cation disorder induced Raman peak in Cu 2 ZnSnS 4 . ► Analysis of spectral features of main Raman peaks from Cu 2 (Fe,Zn)SnS 4 . - Abstract: This work reports the analysis of the vibrational properties of stannite–kesterite Cu 2 (Fe,Zn)SnS 4 compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu 2 FeSnS 4 (CFTS) and kesterite Cu 2 ZnSnS 4 (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm −1 . This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A 1 peak with the chemical composition.

  13. Highly Enhanced Raman Scattering on Carbonized Polymer Films.

    Science.gov (United States)

    Yoon, Jong-Chul; Hwang, Jongha; Thiyagarajan, Pradheep; Ruoff, Rodney S; Jang, Ji-Hyun

    2017-06-28

    We have discovered a carbonized polymer film to be a reliable and durable carbon-based substrate for carbon enhanced Raman scattering (CERS). Commercially available SU8 was spin coated and carbonized (c-SU8) to yield a film optimized to have a favorable Fermi level position for efficient charge transfer, which results in a significant Raman scattering enhancement under mild measurement conditions. A highly sensitive CERS (detection limit of 10 -8 M) that was uniform over a large area was achieved on a patterned c-SU8 film and the Raman signal intensity has remained constant for 2 years. This approach works not only for the CMOS-compatible c-SU8 film but for any carbonized film with the correct composition and Fermi level, as demonstrated with carbonized-PVA (poly(vinyl alcohol)) and carbonized-PVP (polyvinylpyrollidone) films. Our study certainly expands the rather narrow range of Raman-active material platforms to include robust carbon-based films readily obtained from polymer precursors. As it uses broadly applicable and cheap polymers, it could offer great advantages in the development of practical devices for chemical/bio analysis and sensors.

  14. Revelation of rutile phase by Raman scattering for enhanced photoelectrochemical performance of hydrothermally-grown anatase TiO2 film

    Science.gov (United States)

    Cho, Hsun-Wei; Liao, Kuo-Lun; Yang, Jih-Sheng; Wu, Jih-Jen

    2018-05-01

    Photoelectrochemical (PEC) performances of the anatase TiO2 films hydrothermally grown on the seeded fluorine-doped tin oxide (FTO) substrates are examined in this work. Structural characterizations of the TiO2 films were conducted using Raman scattering spectroscopy. Although there is no obvious rutile peak appearing, an asymmetrical peak centered at ∼399 cm-1 was observed in the Raman spectra of the TiO2 films deposited either on the low-temperature-formed seed layers or with low concentrations of Ti precursor. The asymmetrical Raman shift can be deconvoluted into the B1g mode of anatase and Eg mode of rutile TiO2 peaks centered at ∼399 cm-1 and ∼447 cm-1, respectively. Therefore, a minute quantity of rutile phase was inspected in the anatase film using Raman scattering spectroscopy. With the same light harvesting ability, we found that the PEC performance of the anatase TiO2 film was significantly enhanced as the minute quantity of rutile phase existing in the film. It is ascribed to the formation of the anatase/rutile heterojunction which is beneficial to the charge separation in the photoanode.

  15. THE DISCOVERY OF RAMAN SCATTERING IN H II REGIONS

    Energy Technology Data Exchange (ETDEWEB)

    Dopita, Michael A.; Nicholls, David C.; Sutherland, Ralph S.; Kewley, Lisa J.; Groves, Brent A., E-mail: Michael.Dopita@anu.edu.au [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia)

    2016-06-10

    We report here on the discovery of faint extended wings of H α observed out to an apparent velocity of ∼7600 km s{sup −1} in the Orion Nebula (M42) and in five H ii regions in the Large and the Small Magellanic Clouds. We show that these wings are caused by Raman scattering of both the O i and Si ii resonance lines and stellar continuum UV photons with H i followed by radiative decay to the H i n = 2 level. The broad wings also seen in H β and in H γ result from Raman scattering of the UV continuum in the H i n = 4 and n = 5 levels, respectively. The Raman scattering fluorescence is correlated with the intensity of the narrow permitted lines of O i and Si ii. In the case of Si ii, this is explained by radiative pumping of the same 1023.7 Å resonance line involved in the Raman scattering by the Ly β radiation field. The subsequent radiative cascade produces enhanced Si ii λλ 5978.9, 6347.1, and 6371.4 Å permitted transitions. Finally, we show that in O i, radiative pumping of the 1025.76 Å resonance line by the Lyman series radiation field is also the cause of the enhancement in the permitted lines of this species lying near H α in wavelength, but here the process is a little more complex. We argue that all these processes are active in the zone of the H ii region near the ionization front.

  16. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C; Miles, Robin; Davidson, James; Liu, Gang Logan

    2015-11-03

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  17. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2014-07-22

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  18. Nanoscale array structures suitable for surface enhanced raman scattering and methods related thereto

    Science.gov (United States)

    Bond, Tiziana C.; Miles, Robin; Davidson, James C.; Liu, Gang Logan

    2015-07-14

    Methods for fabricating nanoscale array structures suitable for surface enhanced Raman scattering, structures thus obtained, and methods to characterize the nanoscale array structures suitable for surface enhanced Raman scattering. Nanoscale array structures may comprise nanotrees, nanorecesses and tapered nanopillars.

  19. [A new peak detection algorithm of Raman spectra].

    Science.gov (United States)

    Jiang, Cheng-Zhi; Sun, Qiang; Liu, Ying; Liang, Jing-Qiu; An, Yan; Liu, Bing

    2014-01-01

    The authors proposed a new Raman peak recognition method named bi-scale correlation algorithm. The algorithm uses the combination of the correlation coefficient and the local signal-to-noise ratio under two scales to achieve Raman peak identification. We compared the performance of the proposed algorithm with that of the traditional continuous wavelet transform method through MATLAB, and then tested the algorithm with real Raman spectra. The results show that the average time for identifying a Raman spectrum is 0.51 s with the algorithm, while it is 0.71 s with the continuous wavelet transform. When the signal-to-noise ratio of Raman peak is greater than or equal to 6 (modern Raman spectrometers feature an excellent signal-to-noise ratio), the recognition accuracy with the algorithm is higher than 99%, while it is less than 84% with the continuous wavelet transform method. The mean and the standard deviations of the peak position identification error of the algorithm are both less than that of the continuous wavelet transform method. Simulation analysis and experimental verification prove that the new algorithm possesses the following advantages: no needs of human intervention, no needs of de-noising and background removal operation, higher recognition speed and higher recognition accuracy. The proposed algorithm is operable in Raman peak identification.

  20. Raman scattering and attenuated-total-reflection studies of surface-plasmon polaritons

    International Nuclear Information System (INIS)

    Kurosawa, K.; Pierce, R.M.; Ushioda, S.; Hemminger, J.C.

    1986-01-01

    We have made in situ measurements of attenuated total reflection (ATR) and Raman scattering from a layered structure consisting of a glass prism, a thin silver film, an MgF 2 spacer, and a liquid mixture whose refractive index is matched to that of MgF 2 . When the incident angle of the laser beam coincides with the ATR angle, the surface-plasmon polariton (SPP) of the silver film is excited resonantly and the Raman scattering intensity of the liquid shows a maximum. The same effect is observed at the frequency of the Stokes scattered light. By measuring the decrease of the Raman scattering intensity of the liquid with increase of the thickness of the MgF 2 spacer layer, we have determined the decay length (l/sub d/) of the SPP field into the liquid. The measured value of l/sub d/ = 1539 A agrees with the calculated value, 1534 A

  1. Probing the adsorption mechanism in thiamazole bound to the silver surface with Surface-enhanced Raman Scattering and DFT

    Science.gov (United States)

    Biswas, Nandita; Thomas, Susy; Sarkar, Anjana; Mukherjee, Tulsi; Kapoor, Sudhir

    2009-09-01

    Surface-enhanced Raman scattering (SERS) of thiamazole have been investigated in aqueous solution. Thiamazole is an important anti-thyroid drug that is used in the treatment of hyperthyroidism (over activity of the thyroid gland). Due to its medicinal importance, the surface adsorption properties of thiamazole have been studied. The experimental Raman and SERS data are supported with DFT calculations using B3LYP functional with LANL2DZ basis set. From the SERS spectra as well as theoretical calculations, it has been inferred that thiamazole is chemisorbed to the silver surface directly through the sulphur atom and the ring N atom, with a tilted orientation.

  2. Phonon populations by nanosecond-pulsed Raman scattering in Si

    International Nuclear Information System (INIS)

    Compaan, A.; Lee, M.C.; Trott, G.J.

    1985-01-01

    Since the first time-resolved Raman studies of phonon populations under pulsed-laser-annealing conditions, a number of cw Raman studies have been performed which provide a much improved basis for interpreting the pulsed Raman data. Here we present new pulsed Raman results and interpret them with reference to temperature-dependent resonance effects, high-carrier-density effects, phonon anharmonicity, and laser-induced strain effects. The pulsed Raman data: Stokes to anti-Stokes ratios, shift and shape of the first-order peak, and second-order spectra: indicate the existence of a phase in which the Raman signal disappears followed by a rapidly cooling solid which begins within 300 K of the 1685 K normal melting temperature of Si. We identify a major difficulty in pulsed Raman studies in Si to be the decrease in Raman intensity at high temperatures

  3. Surface enhanced Raman scattering

    CERN Document Server

    Furtak, Thomas

    1982-01-01

    In the course of the development of surface science, advances have been identified with the introduction of new diagnostic probes for analytical characterization of the adsorbates and microscopic structure of surfaces and interfaces. Among the most recently de­ veloped techniques, and one around which a storm of controversy has developed, is what has now been earmarked as surface enhanced Raman scattering (SERS). Within this phenomenon, molecules adsorbed onto metal surfaces under certain conditions exhibit an anomalously large interaction cross section for the Raman effect. This makes it possible to observe the detailed vibrational signature of the adsorbate in the ambient phase with an energy resolution much higher than that which is presently available in electron energy loss spectroscopy and when the surface is in contact with a much larger amount of material than that which can be tolerated in infrared absorption experiments. The ability to perform vibrational spectroscopy under these conditions would l...

  4. Raman scattering of light off a superconductor

    International Nuclear Information System (INIS)

    Cuden, C.B.

    1976-01-01

    Raman scattering off a superconducting surface is formulated using Kubo's nonlinear response theory in a form suitable for systematic diagrammatic expansion. The effects of the sample surface are correctly taken into account. It is shown that in the presence of vacuum polarization processes, the contribution to the scattering efficiency from the density-density correlation function considered in the literature, is reduced. The relevant four-vertex parts, describing inelastic scattering of light by electronic excitations via intermediate interband states in a superconductor, are calculated. Frequency and temperature dependence of the relative scattering efficiency for the large momentum transfer (Pippard limit), and constant transition matrix elements, are obtained. The estimated magnitude of the total scattering efficiency is of the order of 10 -11

  5. Polarized Raman spectroscopy of chemically vapour deposited diamond films

    International Nuclear Information System (INIS)

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

    1994-01-01

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

  6. Spatially Resolved Gas Temperature Measurements in an Atmospheric Pressure DC Glow Microdischarge with Raman Scattering

    Science.gov (United States)

    Belostotskiy, S.; Wang, Q.; Donnelly, V.; Economou, D.; Sadeghi, N.

    2006-10-01

    Spatially resolved rotational Raman spectroscopy of ground state nitrogen N2(X^1σg^+) was used to measure the gas temperature (Tg) in a nitrogen dc glow microdischarge (gap between electrodes d˜500 μm). An original backscattering, confocal optical system was developed for collecting Raman spectra. Stray laser light and Raleigh scattering were blocked by using a triple grating monochromator and spatial filters, designed specifically for these experiments. The optical system provided a spatial resolution of electrodes, Tg increased linearly with jd, reaching 500 K at 1000 mA/cm^2 jd for a pressure of 720 Torr. Spatially resolved gas temperature measurements will also be presented and discussed in combination with a mathematical model for gas heating in the microplasma. This work is supported by DoE/NSF.

  7. Review on Raman scattering in semiconductor nanowires: I. theory

    Science.gov (United States)

    Cantarero, Andrés

    2013-01-01

    Raman scattering is a nondestructive technique that is able to supply information on the crystal and electronic structures, strain, temperature, phonon-phonon, and electron-phonon interaction. In the particular case of semiconductor nanowires, Raman scattering provides additional information related to surfaces. Although correct, a theoretical approach to analyze the surface optical modes loses critical information when retardation is neglected. A comparison of the retarded and unretarded approaches clarifies the role of the electric and magnetic polarization in the Raman selection rules. Since most III-V compounds growing in the zincblende phase change their crystal structure to wurtzite when growing as nanowires, the polariton description will be particularized for these two important crystal phases. Confined phonons exist in cylindrical nanowires and couple with longitudinal and transverse modes due to the presence of the nanowire's surface. This coupling vanishes in the case of rotational symmetry. The boundary conditions of the electromagnetic fields on small-size nanowires (antenna effect) have a dramatic effect on the polarization properties of a Raman spectrum.

  8. Resonant stimulation of Raman scattering from single-crystal thiophene/phenylene co-oligomers

    International Nuclear Information System (INIS)

    Yanagi, Hisao; Marutani, Yusuke; Matsuoka, Naoki; Hiramatsu, Toru; Ishizumi, Atsushi; Sasaki, Fumio; Hotta, Shu

    2013-01-01

    Amplified Raman scattering was observed from single crystals of thiophene/phenylene co-oligomers (TPCOs). Under ns-pulsed excitation, the TPCO crystals exhibited amplified spontaneous emission (ASE) at resonant absorption wavelengths. With increasing excitation wavelength to the 0-0 absorption edge, the stimulated resonant Raman peaks appeared both in the 0-1 and 0-2 ASE band regions. When the excitation wavelength coincided with the 0-1 ASE band energy, the Raman peaks selectively appeared in the 0-2 ASE band. Such unusual enhancement of the 0-2 Raman scattering was ascribed to resonant stimulation via vibronic coupling with electronic transitions in the uniaxially oriented TPCO molecules

  9. Photon induced resonant Raman scattering in CdS

    International Nuclear Information System (INIS)

    Muzart, J.; Lluesma, E.G.; Arguello, C.A.; Leite, R.C.C.

    1975-01-01

    A novel aspect of resonant Raman scattering is observed in CdS by means of the ratio of Stokes to anti-Stokes intensities. With increasing temperature, as the forbidden band energy approaches a value that is twice the incident photon energy, (from a Nd-Yag-laser) a large enhancement of the above ratio is observed for both the LO and the 2LO phonon Raman intensities. The results indicate a resonance with the scattered photon. Resonance is only observed for high incident photon intensities. A possible explanation for the above observations is that flooding of the crystal with photons of energy hν induces states of energy hν displaced from the electronic bands by mixing of electronic and photon states

  10. Protonation–deprotonation of the glycine backbone as followed by Raman scattering and multiconformational analysis

    Energy Technology Data Exchange (ETDEWEB)

    Hernández, Belén; Pflüger, Fernando [Groupe de Biophysique Moléculaire, UFR Santé-Médecine-Biologie Humaine, Université Paris 13, Sorbonne Paris Cité, 74 rue Marcel Cachin, 93017 Bobigny cedex (France); Kruglik, Sergei G. [Laboratoire Jean Perrin, FRE 3231, Université Pierre et Marie Curie (Paris 6), Case courrier 138, 75252 Paris Cedex 05 (France); Ghomi, Mahmoud, E-mail: mahmoud.ghomi@univ-paris13.fr [Groupe de Biophysique Moléculaire, UFR Santé-Médecine-Biologie Humaine, Université Paris 13, Sorbonne Paris Cité, 74 rue Marcel Cachin, 93017 Bobigny cedex (France)

    2013-11-08

    Highlights: • New pH-dependent Raman spectra in the middle wavenumber region (1800-300 cm{sup −1}). • New quantum mechanical calculations for exploring the Gly conformational landscape. • Construction of muticonformation based theoretical Raman spectra. - Abstract: Because of the absence of the side chain in its chemical structure and its well defined Raman spectra, glycine was selected here to follow its backbone protonation–deprotonation. The scan of the recorded spectra in the 1800–300 cm{sup −1} region led us to assign those obtained at pH 1, 6 and 12 to the cationic, zwitterionic and anionic species, respectively. These data complete well those previously published by Bykov et al. (2008) [16] devoted to the high wavenumber Raman spectra (>2500 cm{sup −1}). To reinforce our discussion, DFT calculations were carried out on the clusters of glycine + 5H{sub 2}O, mimicking reasonably the first hydration shell of the amino acid. Geometry optimization of 141 initial clusters, reflecting plausible combinations of the backbone torsion angles, allowed exploration of the conformational features, as well as construction of the theoretical Raman spectra by considering the most stable clusters containing each glycine species.

  11. Coupled wave equations theory of surface-enhanced femtosecond stimulated Raman scattering.

    Science.gov (United States)

    McAnally, Michael O; McMahon, Jeffrey M; Van Duyne, Richard P; Schatz, George C

    2016-09-07

    We present a coupled wave semiclassical theory to describe plasmonic enhancement effects in surface-enhanced femtosecond stimulated Raman scattering (SE-FSRS). A key result is that the plasmon enhanced fields which drive the vibrational equation of motion for each normal mode results in dispersive lineshapes in the SE-FSRS spectrum. This result, which reproduces experimental lineshapes, demonstrates that plasmon-enhanced stimulated Raman methods provide unique sensitivity to a plasmonic response. Our derived SE-FSRS theory shows a plasmonic enhancement of |gpu|(2)ImχR(ω)gst (2)/ImχR(ω), where |gpu|(2) is the absolute square of the plasmonic enhancement from the Raman pump, χR(ω) is the Raman susceptibility, and gst is the plasmonic enhancement of the Stokes field in SE-FSRS. We conclude with a discussion on potential future experimental and theoretical directions for the field of plasmonically enhanced coherent Raman scattering.

  12. Raman scattering method and apparatus for measuring isotope ratios and isotopic abundances

    International Nuclear Information System (INIS)

    Harney, R.C.; Bloom, S.D.

    1978-01-01

    Raman scattering is used to measure isotope ratios and/or isotopic abundances. A beam of quasi-monochromatic photons is directed onto the sample to be analyzed, and the resulting Raman-scattered photons are detected and counted for each isotopic species of interest. These photon counts are treated mathematically to yield the desired isotope ratios or isotopic abundances

  13. Raman spectroscopy of white wines.

    Science.gov (United States)

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

    2015-08-15

    The feasibility of exploiting Raman scattering to analyze white wines has been investigated using 3 different wavelengths of the incoming laser radiation in the near-UV (325 nm), visible (532 nm) and near infrared (785 nm). To help in the interpretation of the Raman spectra, the absorption properties in the UV-visible range of two wine samples as well as their laser induced fluorescence have also been investigated. Thanks to the strong intensity enhancement of the Raman scattered light due to electronic resonance with 325 nm laser excitation, hydroxycinnamic acids may be detected and analyzed selectively. Fructose and glucose may also be easily detected below ca. 1000 cm(-1). This feasibility study demonstrates the potential of the Raman spectroscopic technique for the analysis of white wines. Copyright © 2015 Elsevier Ltd. All rights reserved.

  14. Physical chemistry of Nanogap-Enhanced Raman Scattering (NERS)

    Science.gov (United States)

    Suh, Yung Doug; Kim, Hyun Woo

    2017-08-01

    Plasmonically coupled electromagnetic field localization has generated a variety of new concepts and applications, and this has been one of the hottest topics in nanoscience, materials science, chemistry, physics and engineering and increasingly more important over the last decade. In particular, plasmonically coupled nanostructures with ultra-small gap ( 1-nm or smaller) gap have been of special interest due to their ultra-strong optical properties that can be useful for a variety of signal enhancements such surface-enhanced Raman scattering (SERS) and nanoantenna. These promising nanostructures with extraordinarily strong optical signal, however, have rendered a limited success in widespread use and commercialization largely due to the lack of designing principles, high-yield synthetic strategies with nm-level structural controllability and reproducibility and lack of systematic single-molecule and single-particle level studies. All these are extremely important challenges because even small changes ( 1 nm) of the coupled nanogap structures can significant affect plasmon mode and signal intensity and therefore structural and signal reproducibility and controllability can be in question. The plasmonic nanogap-enhanced Raman scattering (NERS) is defined as the plasmonic nanogap-based Raman signal enhancement within plasmonic nanogap particles with 1 nm gap and a Raman dye positioned inside the gap.

  15. Raman scattering of type-I clathrate compounds

    International Nuclear Information System (INIS)

    Takasu, Y.; Hasegawa, T.; Ogita, N.; Udagawa, M.; Avila, M.A.; Takabatake, T.

    2006-01-01

    Lattice dynamical properties of the type-I clathrate compounds of A 8 Ga 16 Ge 30 (A=Eu, Sr, Ba) have been investigated by Raman scattering. We are successful in the assignment of the observed Raman active phonons to proper symmetry and are able to separate the guest atom origin modes from framework origin modes for the first time experimentally. From the measurements of temperature dependence of the guest origin peaks, we also demonstrate the difference of the behavior of the guest atom at high temperature and low temperature

  16. Raman scattering studies of mobile ions in superionic conductor hollandites

    International Nuclear Information System (INIS)

    Shibata, Y.; Suemoto, T.; Ishigame, M.

    1986-01-01

    The Raman spectra of the superionic conductors K/sub 1.6/Mg/sub 0.8/Ti/sub 7.2/O 16 , Cs/sub 1.2/Mg/sub 0.6/Ti/sub 7.4/O 16 , and (KTl)/sub 1.6/Mg/sub 0.8/Ti/sub 7.2/O 16 are measured in the frequency range from 5 to 1000 cm -1 . In the range from 100 to 1000 cm -1 Raman spectra hardly show alkali ion dependence. On the contrary, in the frequency range from 5 to 100 cm -1 , an additional Raman band is observed. This Raman band shows alkali ion dependence. By using the Frenkel-Kontorova model for the hollandite crystal with the given configuration of the mobile ions, it is found that the dependence of vibrational frequency of mobile ions with kinds of alkali ion is well explained and that the concept of 'super unit cell' that is introduced by Beyeler is very useful to explain the Raman bands which are observed below 100 cm -1 in hollandite crystals. (author)

  17. Hydrostatic pressure and temperature effect on the Raman spectra of the molecular crystal 2-amine-1,3,4-thiadiazole

    Science.gov (United States)

    de Toledo, T. A.; da Costa, R. C.; Bento, R. R. F.; Pizani, P. S.

    2018-03-01

    The structural, thermal and vibrational properties of the molecular crystal 2-amine-1,3,4-thiadiazole (ATD) were investigated combining X-ray diffraction, infrared spectroscopy, Raman scattering (in solid and in solution) and thermal analysis as experimental techniques and first principle calculations based on density functional theory using PZ, BLYP in condensed-phase and B3LYP/cc-pVTZ in isolated molecule methods. The structural stability and phonon anharmonicity were also studied using Raman spectroscopy at different temperatures and hydrostatic pressures. A reasonable agreement was obtained between calculated and experimental results. The main difference between experimental and computed structural and vibrational spectra occurred in the intermolecular bond distance Nsbnd H⋯N and stretching modes of NH2. The vibrational spectra were interpreted and assigned based on group theory and functional group analysis assisted by theoretical results, which led to a more comprehensive knowledge about external and internal modes at different thermodynamic conditions. As temperature increases, it was observed the line-width increases and red-shifts, indicating a phonon anharmonicity without a temperature-induced phase transition in the range 10-413 K. However, ATD crystal undergoes a phase transition in the temperature range 413-475 K, as indicated by thermal analysis curve and Raman spectra. Furthermore, increasing pressure from ambient to 3.1 GPa, it was observed the splitting of the external Raman bands centered at 122 cm-1 (at 0.2 GPa), 112 cm-1 (1.1 GPa), 93 cm-1 (2.4 GPa) in two components as well as the appearance of new band near 50 cm-1 at 1.1 GPa, indicating a possible phase-transition. The blue-shift of the Raman bands was associated to anharmonicity of the interatomic potential caused by unit cell contraction.

  18. Anomalous lattice vibrations of monolayer MoS 2 probed by ultraviolet Raman scattering

    KAUST Repository

    Liu, Hsiang Lin; Guo, Huaihong; Yang, Teng; Zhang, Zhidong; Kumamoto, Yasuaki; Shen, Chih Chiang; Hsu, Yu Te; Li, Lain-Jong; Saito, Riichiro; Kawata, Satoshi

    2015-01-01

    We present a comprehensive Raman scattering study of monolayer MoS2 with increasing laser excitation energies ranging from the near-infrared to the deep-ultraviolet. The Raman scattering intensities from the second-order phonon modes are revealed to be enhanced anomalously by only the ultraviolet excitation wavelength 354 nm. We demonstrate theoretically that such resonant behavior arises from a strong optical absorption that forms near the Γ point and of the band structure and an inter-valley resonant electronic scattering by the M-point phonons. These results advance our understanding of the double resonance Raman scattering process in low-dimensional semiconducting nanomaterials and provide a foundation for the technological development of monolayer MoS2 in the ultraviolet frequency range. © the Owner Societies 2015.

  19. Calculated isotropic Raman spectra from interacting H2-rare-gas pairs

    International Nuclear Information System (INIS)

    Gustafsson, M; Głaz, W; Bancewicz, T; Godet, J-L; Maroulis, G; Haskapoulos, A

    2014-01-01

    We report on a theoretical study of the H 2 -He and H 2 -Ar pair trace-polarizability and the corresponding isotropic Raman spectra. The conventional quantum mechanical approach for calculations of interaction-induced spectra, which is based on an isotropic interaction potential, is employed. This is compared with a close-coupling approach, which allows for inclusion of the full, anisotropic potential. It is established that the anisotropy of the potential plays a minor role for these spectra. The computed isotropic collision-induced Raman intensity, which is due to dissimilar pairs in H 2 -He and H 2 -Ar gas mixtures, is comparable to the intensities due to similar pairs (H 2 -H 2 , He-He, and Ar-Ar), which have been studied previously

  20. Raman tensor elements of β-Ga2O3.

    Science.gov (United States)

    Kranert, Christian; Sturm, Chris; Schmidt-Grund, Rüdiger; Grundmann, Marius

    2016-11-03

    The Raman spectrum and particularly the Raman scattering intensities of monoclinic β-Ga 2 O 3 are investigated by experiment and theory. The low symmetry of β-Ga 2 O 3 results in a complex dependence of the Raman intensity for the individual phonon modes on the scattering geometry which is additionally affected by birefringence. We measured the Raman spectra in dependence on the polarization direction for backscattering on three crystallographic planes of β-Ga 2 O 3 and modelled these dependencies using a modified Raman tensor formalism which takes birefringence into account. The spectral position of all 15 Raman active phonon modes and the Raman tensor elements of 13 modes were determined and are compared to results from ab-initio calculations.

  1. Normal Raman and surface enhanced Raman spectroscopic experiments with thin layer chromatography spots of essential amino acids using different laser excitation sources

    Science.gov (United States)

    István, Krisztina; Keresztury, Gábor; Szép, Andrea

    2003-06-01

    A comparative study of the feasibility and efficiency of Raman spectroscopic detection of thin layer chromatography (TLC) spots of some weak Raman scatterers (essential amino acids, namely, glycine and L-forms of alanine, serine, valine, proline, hydroxyproline, and phenylalanine) was carried out using four different visible and near-infrared (NIR) laser radiations with wavelengths of 532, 633, 785, and 1064 nm. Three types of commercial TLC plates were tested and the possibility of inducing surface enhanced Raman scattering (SERS) by means of Ag-sol was also investigated. The spectra obtained from spotted analytes adsorbed on TLC plates were of very different quality strongly depending on the excitation wavelength, the wetness of the samples, and the compounds examined. The best results were obtained with the simple silica TLC plate, and it has been established that the longest wavelength (lowest energy) NIR excitation of a Nd:YAG laser is definitely more suitable for generating normal Raman scattering of analyte spots than any of the visible radiations. Concerning SERS with application of Ag-sol to the TLC spots, 1-3 orders of magnitude enhancement was observed with wet samples, the greatest with the 532 nm radiation and gradually smaller with the longer wavelength excitations. It is shown, however, that due to severe adsorption-induced spectral distortions and increased sensitivity to microscopic inhomogeneity of the sample, none of the SERS spectra obtained with the dispersive Raman microscope operating in the visible region were superior to the best NIR normal FT-Raman spectra, as far as sample identification is concerned.

  2. Mechanism of Pseudogap Detected by Electronic Raman Scattering: Phase Fluctuation or Hidden Order?

    International Nuclear Information System (INIS)

    Hong-Yan, Lu; Yuan, Wan; Xiang-Mei, He; Qiang-Hua, Wang

    2009-01-01

    We study the electronic Raman scattering in the cuprates to distinguish the two possible scenarios of the pseudo-gap normal state. In one scenario, the pseudogap is assumed to be caused by phase fluctuations of the preformed Cooper pairs. We find that pair-breaking peaks appear in both the B 1g and B 2g Raman channels, and they are smeared and tend to shift to the same energy with the increasing strength of phase fluctuations. Thus both channels reflect the same pairing energy scale, irrespectively of the doping level. In another scenario, the pseudogap is assumed to be caused by a hidden order that competes with the superconducting order. As an example, we assume that the hidden order is the d-density-wave (DDW) order. We find analytically and numerically that in the DDW normal state there is no Raman peak in the B 2g channel in a tight-binding model up to the second nearest-neighbor hopping, while the Raman peak in the B 1g channel reflects the energy gap caused by the DDW order. This behavior is in agreement with experiments in the pseudogap normal state. To gain further insights, we also calculate the Raman spectra in the DDW+SC state. We study the doping and temperature dependence of the peak energy in both channels and find a two-gap behavior, which is in agreement with recent Raman experiments. Therefore, our results shed light on the hidden order scenario for the pseudogap

  3. Vibrational dynamics of amorphous metals by inelastic neutron and raman scattering

    International Nuclear Information System (INIS)

    Lustig, N.E.

    1986-01-01

    Time-of-flight inelastic neutron scattering and Raman measurements were performed on amorphous (a-) metals. The neutron-weighted vibrational density of states, G(E), obtained for a-Fe 78 P 22 , a-Ni 82 B 18 and a-Ni 67 B 33 transition metal metalloid alloys (TM-m), indicated two major vibrational bands: a low frequency acoustic-like band and a high frequency optic-like band, derived from TM-TM and TM-m interactions, respectively. Similar neutron measurements were performed on the corresponding polycrystalline (c-) alloys, c-Fe 3 P and c-Ni 2 B. A comparison of the amorphous and crystalline densities of states indicates the elimination of sharp features and the addition of vibrational states at low and high frequencies upon amorphization. The experimental G(E) results for a-Fe 78 P 22 are in good agreement with the theoretically predicted spectrum. A comparison between the a-Ni 67 B 33 and the phenomenologically broadened c-Ni 2 B spectrum indicates a change in the short-range order. This finding is consistent with structural measurements on this alloy. Raman measurements were carried out using interference enhanced Raman spectroscopy (IERS) on thin film Ni-B alloys. The measured spectra provide information about the weighted phonon density of states, and is in good agreement with the neutron results

  4. An effective surface-enhanced Raman scattering template based on a Ag nanocluster-ZnO nanowire array

    International Nuclear Information System (INIS)

    Deng, S; Zhang, X; Loh, K P; Fan, H M; Sow, C H; Cheng, C-L; Foo, Y L

    2009-01-01

    An effective surface-enhanced Raman scattering (SERS) template based on a 3D hybrid Ag nanocluster (NC)-decorated ZnO nanowire array was fabricated through a simple process of depositing Ag NCs on ZnO nanowire arrays. The effects of particle size and excitation energy on the Raman scattering in these hybrid systems have been investigated using rhodamine 6G as a standard analyte. The results indicate that the hybrid nanosystem with 150 nm Ag NCs produces a larger SERS enhancement factor of 3.2 x 10 8 , which is much higher than that of 10 nm Ag NCs (6.0 x 10 6 ) under 532 nm excitation energy. The hybrid nanowire arrays were further applied to obtain SERS spectra of the two-photon absorption (TPA) chromophore T7. Finite-difference time-domain simulations reveal the presence of an enhanced field associated with inter-wire plasmon coupling of the 150 nm Ag NCs on adjacent ZnO nanowires; such a field was absent in the case of the 10 nm Ag NC-coated ZnO nanowire. Such hybrid nanosystems could be used as SERS substrates more effectively than assembled Ag NC film due to the enhanced light-scattering local field and the inter-wire plasmon-enhanced electromagnetic field.

  5. Probing the evaporation of ternary ethanol-methanol-water droplets by cavity enhanced Raman scattering.

    Science.gov (United States)

    Howle, Chris R; Homer, Chris J; Hopkins, Rebecca J; Reid, Jonathan P

    2007-10-21

    Cavity enhanced Raman scattering is used to characterise the evolving composition of ternary aerosol droplets containing methanol, ethanol and water during evaporation into a dry nitrogen atmosphere. Measurements made using non-linear stimulated Raman scattering from these ternary alcohol-water droplets allow the in situ determination of the concentration of the two alcohol components with high accuracy. The overlapping spontaneous Raman bands of the two alcohol components, arising from C-H stretching vibrational modes, are spectrally-resolved in stimulated Raman scattering measurements. We also demonstrate that the evaporation measurements are consistent with a quasi-steady state evaporation model, which can be used to interpret the evaporation dynamics occurring at a range of pressures at a particular evaporation time.

  6. RAMPAC: a Program for Analysis of Complicated Raman Spectra

    NARCIS (Netherlands)

    de Mul, F.F.M.; Greve, Jan

    1993-01-01

    A computer program for the analysis of complicated (e.g. multi-line) Raman spectra is described. The program includes automatic peak search, various procedures for background determination, peak fit and spectrum deconvolution and extensive spectrum handling procedures.

  7. Raman and fluorescent scattering by molecules embedded in small particles

    International Nuclear Information System (INIS)

    Chew, H.W.; McNulty, P.J.

    1983-01-01

    We have formulated a model for fluorescent and Raman scattering by molecules embedded in or in the vicinity of small particles. The model takes into account the size, shape, refractive index, and morphology of the host particles. Analytic and numerical results have been obtained for spherical (one and more layers, including magnetic dipole transitions) cylindrical and spheroidal particles. Particular attention has been given to the spherical case with fluorescent/Raman scatterers uniformly distributed in the particles radiating both coherently and incohorently. Depolarization effects have been studied with suitable averaging process, and good agreement with experiment has been obtained. Analytic and numerical results have been obtained for the elastic scattering of evanescent waves; these results are useful for the study of fluorescent under excitation by evanescent waves

  8. Multiplex coherent anti-Stokes Raman scattering microspectroscopy of brain tissue with higher ranking data classification for biomedical imaging

    Science.gov (United States)

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

    2017-06-01

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

  9. Polar modes in relaxor PbMg.sub.1/3./sub.Nb.sub.2/3./sub.O.sub.3./sub. by hyper-Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Hehlen, B.; Simon, G.; Hlinka, Jiří

    2007-01-01

    Roč. 75, č. 5 (2007), 052104/1-052104/3 ISSN 1098-0121 R&D Projects: GA ČR GA202/06/0411 Institutional research plan: CEZ:AV0Z10100520 Keywords : relaxor * hyper -Raman scattering * lattice vibration * phonon spectra Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.172, year: 2007

  10. A Probabilistic Framework for Detection of Skin Cancer by Raman Spectra

    DEFF Research Database (Denmark)

    Sigurdsson, Sigurdur

    2003-01-01

    . These identified important features are shown to originate from molecular structure changes in lipids and proteins. While the theme of this dissertation is skin cancer diagnosis from Raman spectra, the dimension reduction and the neural network classifier can be applied in general to other types of pattern...... melanoma. The neural network classifier visualization showed that frequency bands, previously identified by visual inspection of Raman spectra by medical experts, were considered important for classification. Moreover, frequency band not previously used for skin lesion classification were identified...... brugt til diagnosering af hudkræft. Disse vigtige frekvensbånd stammer fra forskel i molekyle struktur i lipider og proteiner. Selv om temaet for denne afhandling er hudkræft diagnosering fra Raman spektra, kan dimensions reduceringen og det neurale netværk bruges til andre mønster genkendelses...

  11. Temperature dependence of Brillouin light scattering spectra of acoustic phonons in silicon

    International Nuclear Information System (INIS)

    Olsson, Kevin S.; Klimovich, Nikita; An, Kyongmo; Sullivan, Sean; Weathers, Annie; Shi, Li; Li, Xiaoqin

    2015-01-01

    Electrons, optical phonons, and acoustic phonons are often driven out of local equilibrium in electronic devices or during laser-material interaction processes. The need for a better understanding of such non-equilibrium transport processes has motivated the development of Raman spectroscopy as a local temperature sensor of optical phonons and intermediate frequency acoustic phonons, whereas Brillouin light scattering (BLS) has recently been explored as a temperature sensor of low-frequency acoustic phonons. Here, we report the measured BLS spectra of silicon at different temperatures. The origins of the observed temperature dependence of the BLS peak position, linewidth, and intensity are examined in order to evaluate their potential use as temperature sensors for acoustic phonons

  12. Self organization and low frequency Raman scattering in quartz glasses irradiated by fast neutrons

    International Nuclear Information System (INIS)

    Davranov, O. D.; Subhankulov, I.

    2002-01-01

    In all investigated glasses materials in low frequency region of the IR absorption and Raman scattering spectra intensive and sufficiently broad band with maximum within ∼10-100 cm -1 is observed. The availability of such band is a typical trait of low frequency spectra of amorphous materials and spectroscopic characteristics of this observed low frequency peak in glasses are similar to the spectra of liquids and liquid crystals. In this work the influence of fast neutrons (from 2.5·10 15 to 2.2·10 20 cm -2 ) on location of low frequency peak in quartz glass was investigated with accidental impurities (Ca, Al, Ba, Sb, Pb, Mn, B, Na, Zn), in which summary maintenance of impurities was (10 13 -10 -1 ) mass %). Spectral from of low frequency Raman scattering peak is identical in all glasses independently from their chemical composition. It is discovered that the frequency and amplitude of boson peak increase with increasing of irradiation dose. Maximum of peak is displaced from 54 to 72 cm -1 depending on irradiation dose, but amplitude is increased up to 1.5 times. The increasing of glass density and velocity of acoustic waves propagation are observed. Depending on E-centre ( 28 Si 3+ ) concentration under irradiation dose at first a gradual growth, and then saturation of these centres is observed. The increasing of concentration of centres correlates with the growth of intensity of narrow Raman line 606 cm -1 , connected to oxygen atoms' vibrations on the clusters surface. The irradiation by fast neutron lead to the changing degree of self organization of phase correlation in glasses. It leads to the rising of internal field of phase structure, and consequently, to the changing of wave vector of phase structure, which is displayed in the shift of frequency of boson peak. The changing of self organization degree influences the macroscopic parameters of medium and it is displayed in the changing of glass density and velocity of acoustic waves propagation. The

  13. Fingerprints of quantum spin ice in Raman scattering

    Science.gov (United States)

    Perkins, Natalia

    Quantum spin liquids (QSLs) emerging in frustrated magnetic systems have been a fascinating and challenging subject in modern condensed matter physics for over four decades. In these systems the conventional ordering is suppressed and, instead, unusual behaviors strongly dependent on the topology of the system are observed. The difficulty in the experimental observation of QSLs comes from the fact that unlike the states with broken symmetry, the topological order characteristic of cannot be captured by a local order parameter and thus cannot be detected by local measurements. Identifying QSLs therefore requires reconsideration of experimental probes to find ones sensitive to features characteristic of topological order. The fractionalization of excitations associated with this order can offer signatures that can be probed by conventional methods such as inelastic neutron scattering, Raman or Resonant X-ray scattering experiments. In my talk I will discuss the possibility to use Raman scattering to probe the excitations of Quantum Spin Ice, a model which has long been believed to host a U(1) spin liquid ground state. NSF DMR-1511768.

  14. Theory of Raman scattering in coupled electron-phonon systems

    Science.gov (United States)

    Itai, K.

    1992-01-01

    The Raman spectrum is calculated for a coupled conduction-electron-phonon system in the zero-momentum-transfer limit. The Raman scattering is due to electron-hole excitations and phonons as well. The phonons of those branches that contribute to the electron self-energy and the correction of the electron-phonon vertex are assumed to have flat energy dispersion (the Einstein phonons). The effect of electron-impurity scattering is also incorporated. Both the electron-phonon interaction and the electron-impurity interaction cause the fluctuation of the electron distribution between different parts of the Fermi surface, which results in overdamped zero-sound modes of various symmetries. The scattering cross section is obtained by solving the Bethe-Salpeter equation. The spectrum shows a lower threshold at the smallest Einstein phonon energy when only the electron-phonon interaction is taken into consideration. When impurities are also taken into consideration, the threshold disappears.

  15. Estimating and suppressing background in Raman spectra with an artificial neural network

    DEFF Research Database (Denmark)

    Sigurdsson, Sigurdur; Larsen, Jan; Philipsen, Peter Alshede

    2003-01-01

    In this report we address the problem of skin fluorescence in feature extraction from Raman spectra of skin lesions. We apply a highly automated neural network method for suppressing skin fluorescence from Raman spectrum of skin lesions before dimension reduction with principal components analysi...

  16. Theoretical treatments of stimulated Raman scattering

    International Nuclear Information System (INIS)

    Uehara, Youichi; Sasaki, Wataru

    1981-01-01

    Stimulated Raman scattering (SRS) is a phenomenon, in which the coherent light (Stokes emission) with a shifted wavelength specific to a kind of material mixes in scattered monochromatic light, when the intense monochromatic light (laser light) is scattered by projecting it to the above material. According to the theoretical researches together with the experiments on SRS, it is qualitatively understood to be the phenomenon, in which laser energy is transferred to Stokes emission by the interaction through the optical non-linearity of a material between incident laser beam and the Stokes emission generated by spontaneous emission. The authors have been interested in the application of SRS to plasma diagnostics, and have studied it theoretically for the purpose of investigating its feasibility. Here, the theories reported so far are introduced arranging them. First, the derivation of SRS fundamental equations is explained, though it is limited to the SRS theory for ultrashort pulse laser (TSRS), and Raman media were assumed to be gas or liquid phase. Next, the solution of the equations and the basic properties of TSRS are described. Then, the extension of the TSRS to the cases when the several assumptions, which were set in the solution of the equations, were removed is explained. The extension includes the cases for phase fluctuation, dispersion, existence of anti-Stokes emission, and the presence of laser beam attenuation. Finally, the SRS by the broad band laser is introduced. (Wakatsuki, Y.)

  17. Raman scattering in transition metal compounds: Titanium and compounds of titanium

    Energy Technology Data Exchange (ETDEWEB)

    Jimenez, J.; Ederer, D.L.; Shu, T. [Tulane Univ., New Orleans, LA (United States)] [and others

    1997-04-01

    The transition metal compounds form a very interesting and important set of materials. The diversity arises from the many states of ionization the transition elements may take when forming compounds. This variety provides ample opportunity for a large class of materials to have a vast range of electronic and magnetic properties. The x-ray spectroscopy of the transition elements is especially interesting because they have unfilled d bands that are at the bottom of the conduction band with atomic like structure. This group embarked on the systematic study of transition metal sulfides and oxides. As an example of the type of spectra observed in some of these compounds they have chosen to showcase the L{sub II, III} emission and Raman scattering in some titanium compounds obtained by photon excitation.

  18. Raman scattering by hot polaritons in NaClO/sub 3/

    Energy Technology Data Exchange (ETDEWEB)

    Bogani, F.; Vinattieri, A.

    1985-01-01

    By nonlinear mixing of IR and visible radiation, i.e. coherent Raman scattering by polaritons driven by a CO/sub 2/ laser, it has been possible to get high-resolution spectra for the F-modes of a NaClO/sub 3/ crystal in the region (907/957) cm/sup -1/, where several isotopic modes are present. The obtained independent measurement of the refractive index and absorbance allows an accurate determination of the polariton dispersion curve and its width in q-space. The experimental data confirm the existence of a localized isotopic mode at 931 cm/sup -1/ and a strongly damped isotopic mode near 960 cm/sup -1/. Finally, an accurate measurement of the dispersion of the second-order nonlinear polarizability in the same energy region has been obtained for the first time.

  19. Raman scattering in a Heisenberg S = 1/2 antiferromagnet on the anisotropic triangular lattice

    International Nuclear Information System (INIS)

    Perkins, Natalia; Brenig, Wolfram

    2009-01-01

    We investigate two-magnon Raman scattering from the S = 1/2 Heisenberg antiferromagnet on the triangular lattice (THAF), considering both isotropic and anisotropic exchange interactions. We find that the Raman intensity for the isotropic THAF is insensitive to the scattering geometry, while both the line profile and the intensity of the Raman response for the anisotropic THAF shows a strong dependence on the scattering geometry. For the isotropic case we present an analytical and numerical study of the Raman intensity including both the effect of renormalization of the one-magnon spectrum by 1 = S corrections and final-state magnonmagnon interactions. The bare Raman intensity displays two peaks related to one-magnon van-Hove singularities. We find that 1 = S self-energy corrections to the one-magnon spectrum strongly modify this intensity profile. The central Raman-peak is significantly enhanced due to plateaus in the magnon dispersion, the high frequency peak is suppressed due to magnon damping, and the overall spectral support narrows considerably. Additionally we investigate final-state interactions by solving the Bethe-Salpeter equation to O(1 = S). In contrast to collinear antiferromagnets, the non-collinear nature of the magnetic ground state leads to an irreducible magnon scattering which is retarded and non-separable already to lowest order. We show that final-state interactions lead to a rather broad Raman-continuum centered around approximately twice the 'roton'-energy.

  20. Laser Thomson Scattering, Raman Scattering and laser-absorption diagnostics of high pressure microdischarges

    International Nuclear Information System (INIS)

    Donnelly, Vincent M; Belostotskiy, Sergey G; Economou, Demetre J; Sadeghi, Nader

    2010-01-01

    Laser scattering experiments were performed in high pressure (100s of Torr) parallel-plate, slot-type DC microdischarges operating in argon or nitrogen. Laser Thomson Scattering (LTS) and Rotational Raman Scattering were employed in a novel, backscattering, confocal configuration. LTS allows direct and simultaneous measurement of both electron density (n e ) and electron temperature (T e ). For 50 mA current and over the pressure range of 300 - 700 Torr, LTS yielded T e = 0.9 ± 0.3 eV and n e = (6 ± 3)·10 13 cm -3 , in reasonable agreement with the predictions of a mathematical model. Rotational Raman spectroscopy (RRS) was employed for absolute calibration of the LTS signal. RRS was also applied to measure the 3D gas temperature (T g ) in nitrogen DC microdischarges. In addition, diode laser absorption spectroscopy was employed to measure the density of argon metastables (1s5 in Paschen notations) in argon microdischarges. The gas temperature, extracted from the width of the absorption profile, was compared with T g values obtained by optical emission spectroscopy.

  1. Using a Spectrofluorometer for Resonance Raman Spectra of Organic Molecules

    Directory of Open Access Journals (Sweden)

    Vadivel Masilamani

    2017-01-01

    Full Text Available Scattering (Rayleigh and Raman and fluorescence are two common light signals that frequently occur together, confusing the researchers and graduate students experimenting in molecular spectroscopy laboratories. This report is a brief study presenting a clear discrimination between the two signals mentioned, employing a common spectrofluorometer such as the PerkinElmer LS 55. Even better, the resonance Raman signal of a molecule (e.g., acetone can be obtained elegantly using the same instrument.

  2. Diode Laser Raman Scattering Prototype Gas-Phase Environmental Monitoring

    National Research Council Canada - National Science Library

    Benner, Robert

    1999-01-01

    We proposed developing a diode-laser-based, full spectrum Raman scattering instrument incorporating a multipass, external cavity enhancement cell for full spectrum, gas phase analysis of environmental pollutants...

  3. 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...

  4. Microwave assisted in situ synthesis of Ag–NaCMC films and their reproducible surface-enhanced Raman scattering signals

    International Nuclear Information System (INIS)

    Jiang, Tao; Li, Junpeng; Zhang, Li; Wang, Binbing; Zhou, Jun

    2014-01-01

    Graphical abstract: Two kinds of Ag–NaCMC films for surface-enhanced Raman scattering (SERS) were prepared by conventional heating and microwave assisted in situ reduction methods without any additional capping or reducing agents. A relatively narrow and symmetric surface plasmon resonance band was observed in the absorption spectra of the films fabricated by the microwave assisted in situ reduction method. More uniform silver nanoparticles (NPs) implied by the symmetric absorption spectrum were further confirmed by the scanning electron microscopy images. After the simulation of the E-field intensity distribution around the silver NPs in NaCMC film, the Raman scattering enhancement factors (EFs) of these films were then investigated with 4-mercaptobenzoic acid molecule as a SERS reporter. Improved reproducibility of SERS signal was obtained in the microwave assisted synthesized Ag–NaCMC film, although it maintained an EF as only 1.11 × 10 8 . The reproducible SERS signal of the Ag–NaCMC film is particularly attractive and this microwave assisted in situ reduction method is suitable for the production of excellent substrate for biosensor application. - Highlights: • The synthesis of Ag–NaCMC films was successfully fulfilled by a low-cost microwave method. • More uniform silver nanoparticles were observed in Ag–NaCMC film synthesized by microwave. • Improved reproducibility of SERS signal was obtained in microwave synthesized Ag–NaCMC film. - Abstract: Two kinds of Ag–NaCMC films for surface-enhanced Raman scattering (SERS) were prepared by conventional heating and microwave assisted in situ reduction methods without any additional capping or reducing agents. A relatively narrow and symmetric surface plasmon resonance band was observed in the absorption spectra of the films fabricated by the microwave assisted in situ reduction method. More uniform silver nanoparticles (NPs) implied by the symmetric absorption spectrum were further confirmed by

  5. Micro-Raman scattering and dielectric investigations of phase transitions behavior in the PbHf0.7Sn0.3O3 single crystal

    Science.gov (United States)

    Jankowska-Sumara, Irena; Ko, Jae-Hyeon; Podgórna, Maria; Oh, Soo Han; Majchrowski, Andrzej

    2017-09-01

    Raman light scattering was used to detect the sequence of transitions in a PbHf1-xSnxO3 (PHS) single crystal with x = 0.30 in a temperature range of 77-873 K. Changes of Raman spectra were observed in the vicinity of structural phase transitions: between the antiferroelectric (AFE1)-antiferroelectric (AFE2)—intermediate—paraelectric phases. Light scattering and dielectric investigations were used to find out the nature and sequence of the phase transition, as well as the large dielectric permittivity values measured at the phase transition, by searching for the soft-phonon-mode behavior. The experimentally recorded spectra were analyzed in terms of the damped-harmonic oscillator model for the phonon bands. It is demonstrated that the structural phase transformations in PHS can be considered as the result of softening of many modes, not only the ferroelectric one. It was also proved that locally broken symmetry effects are present at temperatures far above the Curie temperature and are connected with the softening of two optic modes of different nature.

  6. In situ surface enhanced resonance Raman scattering analysis of a reactive dye covalently bound to cotton.

    Science.gov (United States)

    White, P C; Munro, C H; Smith, W E

    1996-06-01

    An in situ surface enhanced resonance Raman scattering (SERRS) procedure is described for the analysis of a reactive dye covalently bound to a single strand of a cotton fibre. This procedure can be completed in 5 h, whereas an alternative enzyme digestion method takes approximately 21 h. These two fibre preparation methods give similar spectra from picogram quantities of dye present on a 2-5 mm length of fibre. The in situ nature of the analysis and the small sample size make this method particularly suitable for forensic applications.

  7. Raman scattering by hot and thermal polaritons in crystal quartz

    Energy Technology Data Exchange (ETDEWEB)

    Bogani, F.; Colocci, M.; Neri, M.; Querzoli, R.

    1984-11-01

    Nonlinear mixing of IR and visible radiation, i.e. coherent Raman scattering by polaritons driven by a CO/sub 2/ laser, has been used to obtain the dispersion curve and its width in q-space of the polariton associated to the E-phonon at 1065 cm/sup -1/ in crystal quartz. It is shown in this paper that a direct method to determine independently, with high precision, the refractive index and absorbance of a crystal can be obtained in this way. The results are compared with accurate data obtained from Raman scattering by polaritions in thermal equilibrium and very good agreement is found between the two measurements. It is finally shown that nonlinear-mixing techniques turn out to be completely consistent with the simple picture of scattering of light by hot polaritons.

  8. Time-dependent micro-Raman scattering studies of polyvinyl ...

    Indian Academy of Sciences (India)

    2014-02-15

    Feb 15, 2014 ... Micro-Raman scattering; surface plasmons; silver nanoparticles; polyvinyl alcohol. PACS Nos 74.25.nd; ... as well as their characterization. Added .... 3.2 Surface plasmon absorption of thin films of PVA + AgNO3. The surface ...

  9. Raman scattering of quasimodes in ZnO

    International Nuclear Information System (INIS)

    Alarcon-Llado, E; Cusco, R; Artus, L; Jimenez, J; Wang, B; Callahan, M

    2008-01-01

    The angular dependence of the optical phonons of high-quality bulk ZnO has been systematically studied by means of Raman scattering. We report the observation of quasi-TO and quasi-LO modes for propagation directions covering the whole a-c mixing plane using a beveled ZnO single crystal sample. Scattering experiments performed in two different configuration geometries indicate that birefringence effects are not relevant for the phonon analysis in this material. The observed angular dependence of the quasimode frequencies is in good agreement with Loudon's model.

  10. Stimulated Raman scattering and hot-electron production

    International Nuclear Information System (INIS)

    Drake, R.P.; Turner, R.E.; Lasinski, B.F.; Estabrook, K.G.; Campbell, E.M.; Wang, C.L.; Phillion, D.W.; Williams, E.A.; Kruer, W.L.

    1985-01-01

    High-intensity laser light can excite parametric instabilities that scatter or absorb it. One instability that can arise when laser light penetrates a plasma is sub-quarter-critical stimulated Raman (SQSR) scattering. It occurs below the quarter-critical density of the incident light and involves the decay of the incident light wave into a scattered light wave and electron plasma wave. The scattered-light wavelength ranges from 1 to 2 times that of the incident light, depending on the plasma density and temperature. This article reports studies of SQSR scattering and hot-electron production in plasmas produced by irradiating thick gold targets with up to 4 kJ of 0.53-μm light in 1-ns (FWHM) pulses. These studies have important implications for laser fusion. Hot electrons attributed to the SQSR instability can increase the difficulty of achieving high-gain implosions by penetrating and preheating the fusion fuel

  11. Rigorous results in quantum theory of stimulated Raman scattering

    International Nuclear Information System (INIS)

    Rupasov, V.I.

    1993-01-01

    The modern theory of stimulated Raman scattering (SRS) of light in resonant media is based on the investigations of appropriate integrable models of the classical field theory by means of the inverse problem method. But, strictly speaking, Raman scattering is a pure spontaneous process and, hence, it is necessary to take into account a quantum nature of the phenomenon. Moreover, there are some questions and problems, for example, the problem of scattered photons statistics, which can be studied only within the framework of the quantum field theory. We have developed an exact quantum theory of SRS for the case of point-like geometry of resonant media (two-level atoms or harmonic oscillators) of the radius r much-lt λ 0 , where λ 0 is the typical wavelength of the light, but all our results are also valid for the case of short extended medium of the length L much-lt l p (l p is the typical size of pulses) when the spatially homogeneous approximation is valid

  12. Phase discrimination in CdSe structures by means of Raman scattering

    International Nuclear Information System (INIS)

    Cusco, R.; Artus, L.; Consonni, V.; Bellet-Amalric, E.; Andre, R.

    2017-01-01

    Raman spectra of epitaxial layers of CdSe grown by molecular beam epitaxy have been measured for the cubic (zincblende) and hexagonal (wurtzite) phases. The Raman spectra are examined in the light of density functional calculations for these two highly similar structures. Characteristic Raman frequencies and spectral features associated with the different symmetry are discussed and reliable criteria for phase discrimination based on Raman spectroscopy are proposed. Although LO frequencies are virtually identical in both structures and may be affected by size effects, the observation of a low energy E 2 mode at 33 cm -1 unambiguously identifies the wurtzite structure and can be used as a specific fingerprint to distinguish between these two phases in CdSe-based nanostructures. The slightly lower LO frequency measured in the zincblende epitaxial layer is ascribed to residual tensile strain. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. Phase discrimination in CdSe structures by means of Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Cusco, R.; Artus, L. [Institut Jaume Almera (ICTJA-CSIC), Consejo Superior de Investigaciones Cientificas, Lluis Sole i Sabaris s.n., 08028 Barcelona (Spain); Consonni, V. [Universite Grenoble Alpes and CNRS, LMGP, 38016 Grenoble (France); Bellet-Amalric, E. [Universite Grenoble Alpes and CEA, INAC-PHEILQS, Nanophysique et Semiconducteurs Group, 38000 Grenoble (France); Andre, R. [Universite Grenoble Alpes and CNRS, Institut Neel, Nanophysique et Semiconducteurs Group, 38000 Grenoble (France)

    2017-05-15

    Raman spectra of epitaxial layers of CdSe grown by molecular beam epitaxy have been measured for the cubic (zincblende) and hexagonal (wurtzite) phases. The Raman spectra are examined in the light of density functional calculations for these two highly similar structures. Characteristic Raman frequencies and spectral features associated with the different symmetry are discussed and reliable criteria for phase discrimination based on Raman spectroscopy are proposed. Although LO frequencies are virtually identical in both structures and may be affected by size effects, the observation of a low energy E{sub 2} mode at 33 cm{sup -1} unambiguously identifies the wurtzite structure and can be used as a specific fingerprint to distinguish between these two phases in CdSe-based nanostructures. The slightly lower LO frequency measured in the zincblende epitaxial layer is ascribed to residual tensile strain. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Study of hot carrier relaxation in quantum wells by subpicosecond Raman scattering

    International Nuclear Information System (INIS)

    Kim, Dai-sik; Yu, P.Y.

    1990-03-01

    Relaxation of hot carriers excited by subpicosecond laser pulses has been studied by Raman scattering in GaAs/AlAs multiple quantum wells with well widths varying between 100 and 1000 Angstrom. The hot phonon population observed by Raman scattering is found to decrease with the well width despite the fact that the hot electron temperature remains constant. The results are explained in terms of confinement of both electrons and optical phonons in quantum wells

  15. Transition from the radiationless resonant Raman scattering to the normal Auger decay in a charge transfer system

    International Nuclear Information System (INIS)

    Ohno, Masahide

    2006-01-01

    The transition from the radiationless resonant Raman scattering to the normal Auger decay in resonant Auger-electron spectroscopy (RAES) spectra of charge transfer (CT) systems is discussed by treating the relaxation and the core-hole decay of the excited core-hole state on the same footing by a many-body theory. When the resonantly excited electron remains at the excited atomic site during the core-hole decay, the RAES spectrum shows the characteristic feature of the resonant Auger-Raman effect, whereas when the excited electron has been transferred from the atomic site before the core-hole decays, the RAES spectrum shows the normal Auger decay. The present theory supports the interpretation of the variation with photon energy of the intensity ratio of the latter spectrum to the former one in the RAES spectrum by the Ar 2p → 4s resonance of Ar atoms adsorbed on Ru(0 0 1) surface reported by Keller et al. [C. Keller, M. Stichler, G. Comelli, F. Esch, S. Lizzit, D. Menzel, W. Wurth, Phys. Rev. B 57 (1998) 11951]. The transition from the radiationless resonant Raman scattering to the normal Auger decay in the RAES spectrum of CuO reported by Finazzi et al. [M. Finazzi, G. Ghiringhell, O. Tjernberg, Ph. Ohresser, N.B. Brookes, Phys. Rev. B 61 (2000) 4629] is discussed in terms of the relaxation of the resonantly excited core-hole state to the core-electron ionized main-line state by the hole-particle excitations. The merging of the resonant Raman-Auger-electron kinetic energy into the normal one about 2 eV above the absorption maximum in Cu 2 O reported by Finazzi et al. [M. Finazzi, G. Ghiringhell, O. Tjernberg, Ph. Ohresser, N.B. Brookes, Phys. Rev. B 61 (2000) 4629] is explained in terms of the change in the characteristics of the screening electron in the two-hole final state. The Ti L 23 -M 23 V RAES spectra of TiO 2 and TiO 2-x are also analyzed

  16. High-Resolution Infrared and Raman Spectra of the Polycrystalline Sinomenine Hydrochloride

    Directory of Open Access Journals (Sweden)

    Liu Xiao-Dong

    2016-01-01

    Full Text Available High-resolution infrared and Raman spectra of the polycrystalline sinomenine (SM hydrochloride have been measured to work out its whole really existing vibrational spectral bands. Except for the hydroxyl stretching modes and IR active bands less than 400 cm−1, most normal modes (about 34 are both IR and Raman active. In addition, 8 Raman bands less than 400 cm−1 are tentatively assigned, for the first time to our knowledge, to stretching/bending modes of the aromatic-ring−methoxyls and (SMH+–Cl− ions, respectively.

  17. Raman Scattering Study of the Soft Phonon Mode in the Hexagonal Ferroelectric Crystal KNiCl 3

    Science.gov (United States)

    Machida, Ken-ichi; Kato, Tetsuya; Chao, Peng; Iio, Katsunori

    1997-10-01

    Raman spectra of some phonon modes of the hexagonal ferroelectriccrystal KNiCl3are obtained in the temperature range between 290 K and 590 K, which includes the structural phase transition point T2(=561 K) at which previous measurements of dielectric constant and spontaneouspolarization as a function of temperature had shown that KNiCl3 undergoes a transition between polar phases II and III. An optical birefringence measurement carried outas a complement to the present Raman scattering revealed that this transition is of second order. Towards this transition point, the totally symmetric phonon mode with the lowest frequency observed in the room-temperature phasewas found to soften with increasing temperature.The present results provide new information on the phase-transitionmechanism and the space groups of thehigher (II)- and lower (III)-symmetric phases around T2.

  18. Development of single shot 1D-Raman scattering measurements for flames

    Science.gov (United States)

    Biase, Amelia; Uddi, Mruthunjaya

    2017-11-01

    The majority of energy consumption in the US comes from burning fossil fuels which increases the concentration of carbon dioxide in the atmosphere. The increasing concentration of carbon dioxide in the atmosphere has negative impacts on the environment. One solution to this problem is to study the oxy-combustion process. A pure oxygen stream is used instead of air for combustion. Products contain only carbon dioxide and water. It is easy to separate water from carbon dioxide by condensation and the carbon dioxide can be captured easily. Lower gas volume allows for easier removal of pollutants from the flue gas. The design of a system that studies the oxy-combustion process using advanced laser diagnostic techniques and Raman scattering measurements is presented. The experiments focus on spontaneous Raman scattering. This is one of the few techniques that can provide quantitative measurements of the concentration and temperature of different chemical species in a turbulent flow. The experimental design and process of validating the design to ensure the data is accurate is described. The Raman data collected form an experimental data base that is used for the validation of spontaneous Raman scattering in high pressure environments for the oxy-combustion process. NSF EEC 1659710.

  19. Theory of two-magnon Raman scattering in alkaline iron selenide superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.S. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China); Zhang, A.M. [Department of Physics, Renmin University of China, Beijing 100872 (China); Xu, T.F. [Department of Physics, Yanshan University, Qinhuangdao 006004 (China); Wu, W.C., E-mail: wu@phy.ntnu.edu.tw [Department of Physics, National Taiwan Normal University, Taipei 11677, Taiwan (China)

    2014-11-15

    Highlights: • Two-magnon Raman scattering is theoretically studied for alkaline iron selenides. • Underlying spin interactions of the √(5)×√(5) AF superstructure are investigated in details. • Optimal set of exchange parameters is revealed when fitting to experiments. - Abstract: Motivated by the recent experiment of two-magnon Raman scattering in alkaline iron selenide superconductors (Zhang et al., 2012), we investigate in details the underlying spin interactions of the √(5)×√(5) antiferromagnetic superstructure. Based on the linear spin wave approximation, the Fleury-London (FL) two-magnon Raman cross-sections are calculated. By comparing theoretical results with the Raman data in both A{sub g} and B{sub g} channels, an optimal set of exchange parameters which are consistent with the fitting to the neutron scattering data are obtained. It reveals that the experimentally observed broad and asymmetric peaks around 1600 cm{sup −1} are dominantly originated from quasiparticle excitations in two nearly degenerate magnon bands in the (0,±π) and (±π,0) directions. The result thus supports that the magnetic properties in alkaline iron selenide AFe{sub 1.6+x}Se{sub 6} superconductors can be basically described by the quantum spin model with up to third nearest-neighbor exchange couplings.

  20. Arsenic speciation by X-ray spectroscopy using resonant Raman Scattering

    Energy Technology Data Exchange (ETDEWEB)

    Sanchez, H.J.; Leani, J.J. [Universidad Nacional de Cordoba, Cba (Argentina); Perez, C.A. [Laboratorio Nacional de Luz Sincrotron (LNLS), Campinas, SP (Brazil)

    2012-07-01

    Full text: The toxicity of arsenic species is widely known. A realistic evaluation of the risk posed by As depends on accurate determination of As speciation, because its toxicity and mobility varies with oxidation state and chemical environment. The most toxic species are inorganic As (III) and As (V) called respectively arsenite or trivalent arsenic, and arsenate or pentavalent arsenic. Recently, x-ray Resonant Raman Scattering spectroscopy has been successfully employed to determine the oxidation state of metals. In this work we use RRS spectroscopy to perform arsenic speciation. The measurements were carried out in XRF station of the D09B-XRF beamline at the Brazilian synchrotron facility (LNLS, Campinas). Mineral samples of As in different oxidation states (As(III) and AS(V)), and two biological forms of arsenic (monomethylarsonic acid (MMA(V) and dimethylarsinic acid DMA(V)) were analysed. The samples were diluted, deposited on silicon wafers and allowed to dry. The amount of liquid deposited on the reflector before evaporation was 20 microliters for all the specimens. These samples were irradiated with monochromatic photons of 11816 eV, i.e., below the K-edge of arsenic in order to inspect the Raman emissions. The measuring lifetime was 3600 sec for each sample. Spectra were analysed with specific programs for spectrum analysis using non-conventional functions for data fitting, i.e., modified Voight functions (for Compton peaks), Gaussian functions for fluorescent and for low intensity peaks (such as escape peaks and other contributions), and polynomial functions for the background. Raman peaks were fitted using specific functions. In this work we have shown that resonant Raman scattering spectroscopy can be used to analyse arsenic species. The method is very simple and reliable. The most important feature of this method relies in the possibility of using the same spectrometer of XRF analysis or TXRF analysis. In this way, practically in the same experiment

  1. An analysis of scattered light in low dispersion IUE spectra

    Science.gov (United States)

    Basri, G.; Clarke, J. T.; Haisch, B. M.

    1985-01-01

    A detailed numerical simulation of light scattering from the low-resolution grating in the short wavelength spectrograph of the IUE Observatory was developed, in order to quantitatively analyze the effects of scattering on both continuum and line emission spectra. It is found that: (1) the redistribution of light by grating scattering did not appreciably alter either the shape or the absolute flux level of continuum spectra for A-F stars; (2) late-type stellar continua showed a tendency to flatten when observed in scattered light toward the shorter wavelengths; and (3) the effect of grating scattering on emission lines is to decrease measured line intensities by an increasing percentage toward the shorter wavelengths. The spectra obtained from scattering experiments for solar-type and late type stars are reproduced in graphic form.

  2. Infrared and Raman spectra, DFT-calculations and spectral assignments of germacyclohexane

    Energy Technology Data Exchange (ETDEWEB)

    Aleksa, V., E-mail: valdemaras.aleksa@ff.vu.lt; Ozerenskis, D.; Pucetaite, M.; Sablinskas, V. [Faculty of Physics, Vilnius University, Sauletekio av. 9, block 3, Vilnius, LT-10222 (Lithuania); Cotter, C.; Guirgis, G. A. [Department of Chemistry and Biochemistry, College of Charleston, Charleston, SC 29424 (United States)

    2015-03-30

    Raman spectra of germacyclohexane in liquid and solid states were recorded and depolarization data obtained. Infrared absorption spectra of the vapor and liquid have been studied. The wavenumbers of the vibrational modes were derived in the harmonic and anharmonic approximation in B3LYP/ccpVTZ calculations. According to the calculations, germacyclohexane exists in the stable chair conformation, whereas a possible twist form should have more than 15 kJ·mol{sup -1} higher enthalpy of formation what makes this conformer experimentally not observable. The 27 A' and 21 A'' fundamentals were assigned on the basis of the calculations and infrared and Raman band intensities, contours of gas phase infrared spectral bands and Raman depolarization measurements. An average discrepancy of ca. 0.77 % was found between the observed and the calculated anharmonic wavenumbers for the 48 modes. Substitution of carbon atom with Ge atom in the cyclohexane ring is reasoning flattening of the ring.

  3. Effect of hormonal variation on in vivo high wavenumber Raman spectra improves cervical precancer detection

    Science.gov (United States)

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

    2012-03-01

    Raman spectroscopy is a unique analytical probe for molecular vibration and is capable of providing specific spectroscopic fingerprints of molecular compositions and structures of biological tissues. The aim of this study is to improve the classification accuracy of cervical precancer by characterizing the variations in the normal high wavenumber (HW - 2800-3700cm-1) Raman spectra arising from the menopausal status of the cervix. A rapidacquisition near-infrared (NIR) Raman spectroscopic system was used for in vivo tissue Raman measurements at 785 nm excitation. Individual HW Raman spectrum was measured with a 5s exposure time from both normal and precancer tissue sites of 15 patients recruited. The acquired Raman spectra were stratified based on the menopausal status of the cervix before the data analysis. Significant differences were noticed in Raman intensities of prominent band at 2924 cm-1 (CH3 stretching of proteins) and the broad water Raman band (in the 3100-3700 cm-1 range) with a peak at 3390 cm-1 in normal and dysplasia cervical tissue sites. Multivariate diagnostic decision algorithm based on principal component analysis (PCA) and linear discriminant analysis (LDA) was utilized to successfully differentiate the normal and precancer cervical tissue sites. By considering the variations in the Raman spectra of normal cervix due to the hormonal or menopausal status of women, the diagnostic accuracy was improved from 71 to 91%. By incorporating these variations prior to tissue classification, we can significantly improve the accuracy of cervical precancer detection using HW Raman spectroscopy.

  4. A quarter century of stimulated Raman scattering

    International Nuclear Information System (INIS)

    Bloembergen, N.

    1987-01-01

    To round out a quarter century of SRS the timing of this writing (1986) requires a look ahead of only one year into the future. The proceedings of the 10th International Conference on Raman Spectroscopy present a picture of current activity. Further progress will be made in time-resolved spectroscopy with subpicosecond resolution, in the study of hyper-Raman and other higher order effects with CARS, in extension of resonant Raman excitation in the UV region of spectrum, and in the development of Raman laser sources. During past few years extensive theoretical investigations have been made for four-wave light mixing in the case of one or more very strong light beams. The perturbation approach for those fields ceases to be valid. If only one light field is strong, the usual approach is to make a transformation to a rotating coordinate system so that the strong Hamiltonian for this light field becomes time-independent. Very recently these techniques have been extended to the case of two or more strong fields. CARS-type experiments with strong beams are likely to receive more attention. Extrapolation of the current activities instills confidence in the vitality of stimulated Raman scattering for the foreseeable future

  5. Vibrational properties of stannite and kesterite type compounds: Raman scattering analysis of Cu{sub 2}(Fe,Zn)SnS{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Fontane, X.; Izquierdo-Roca, V.; Saucedo, E. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); Schorr, S. [Free University Berlin, Institute of Geological Sciences, Malteserstr. 74-100, Berlin (Germany); Yukhymchuk, V.O.; Valakh, M.Ya. [V.E. Lahskaryov Institute of Semiconductor Physics, National Academy of Sciences, Prospekt Nauki 41, Kiev 03028 (Ukraine); Perez-Rodriguez, A., E-mail: aperezr@irec.cat [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain); Morante, J.R. [IREC: Catalonia Institute for Energy Research, C. Jardins de les Dones de Negre 1, Sant Adria del Besos, Barcelona 08930 (Spain); IN2UB, Departament d' Electronica, Universitat de Barcelona, C. Marti i Franques 1, 08028 Barcelona (Spain)

    2012-10-25

    Highlights: Black-Right-Pointing-Pointer Analysis of main and weaker Raman peaks from Cu{sub 2}FeZnS{sub 4} and Cu{sub 2}ZnSnS{sub 4} compounds. Black-Right-Pointing-Pointer Identification of a cation disorder induced Raman peak in Cu{sub 2}ZnSnS{sub 4}. Black-Right-Pointing-Pointer Analysis of spectral features of main Raman peaks from Cu{sub 2}(Fe,Zn)SnS{sub 4}. - Abstract: This work reports the analysis of the vibrational properties of stannite-kesterite Cu{sub 2}(Fe,Zn)SnS{sub 4} compounds that has been performed by Raman scattering measurements. The detailed analysis of the experimental spectra has allowed determining the frequency and symmetry assignment of the main and weaker peaks from both stannite Cu{sub 2}FeSnS{sub 4} (CFTS) and kesterite Cu{sub 2}ZnSnS{sub 4} (CZTS) phases. The measurements performed in the kesterite CZTS samples have also revealed the presence of local inhomogeneities that are characterised by an additional peak in the spectra at about 331 cm{sup -1}. This peak has been related to the presence in these local regions of a high degree of disorder in the cation sublattice, in agreement with previous neutron diffraction analysis in similar samples. Finally, the spectra from the solid solution alloys show a one-mode behaviour of the main A/A{sub 1} peak with the chemical composition.

  6. Interplay of structure and magnetism in ruthenocuprates: a Raman scattering and dilatometry study

    Science.gov (United States)

    Fainstein, A.; Ramos, C. A.; Pregliasco, R. G.; Butera, A.; Trodahl, H. J.; Williams, G. V. M.; Tallon, J. L.

    2002-07-01

    We present a Raman scattering and dilatometry study of polycrystalline samples of the magnetic superconducting ruthenocuprates RuSr 2Gd 2- xCe xCu 2O 10+ δ (RuGd 1222) and RuSr 2GdCu 2O 8 (RuGd 1212). In the Raman spectra a high-temperature diffusive-like laser-tail develops below the magnetic ordering temperature ( TM) into an underdamped peak which shifts up to ˜130 cm-1. A line assigned to O(Ru) phonons hardens, narrows and strengthens strongly below TM. Finally, a phonon peak appears below TM at ˜590 cm-1. These three magnetic-order-dependent features are observed for RuGd 1212 and for RuGd 1222 with x=1.0, but do not appear for x=0.5. Dilatometry measurements, on the other hand, evidence a change of the expansion coefficient at TM. These results point to a structural effect accompanying the magnetic order, and suggest a complex interplay of spin and lattice degrees of freedom in these ruthenocuprates.

  7. Surface-Enhanced Raman Scattering of MEH-PPV on Gold and Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Beatriz R. Moraes

    2018-01-01

    Full Text Available The interaction of poly[2-methoxy-5-(2-ethylhexyloxy-1,4-phenylenevinylene] (MEH-PPV with Au or Ag nanospheres, Au nanostars, and Ag nanoprisms was investigated using surface-enhanced Raman scattering (SERS. The SERS investigation showed that adsorption of MEH-PPV strongly depends on the nature of the nanoparticle surface. On gold nanostars that present a thick layer of capping polymer, SERS spectrum is only observed in relatively concentrated MEH-PPV solution (1 mmol L−1. On the other hand, Au and Ag nanospheres present SERS spectra down to 10−6 mol L−1 and no chemical interaction of MEH-PPV and metal surface is observed. The spectra of MEH-PPV on Ag nanoprisms with PVP as stabilizing agent suggest that the capping polymer induces a planar conformation of MEH-PPV and consequently an increase of conjugation length. These results give support for the application of MEH-PPV on optoelectronics in which interfacial effects are critical in the device efficiency and stability.

  8. Surface-Enhanced Raman Scattering of Bacteria in Microwells Constructed from Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    Mustafa Çulha

    2012-01-01

    Full Text Available Whole bacterial cell characterization is critically important for fast bacterial identification. Surface-enhanced Raman scattering (SERS is proven to be powerful technique to serve such a goal. In this study, the characterization of whole bacterial cells in the microwells constructed from colloidal silver nanoparticles (AgNPs with “convective-assembly” method is reported. The proper size of the microwells for the model bacteria, Escherichia coli and Staphylococcus cohnii, is determined to be 1.2 μm from their electron microscopy images. A minimum dilution factor of 20 is necessary for the bacterial samples collected from growth media to diminish the bacterial aggregation to place the bacterial cells into the microwells. The constructed microwell structures are tested for their bacterial SERS performance and compared to the SERS spectra obtained from the samples prepared with a simple mixing of bacteria and AgNPs for the same bacteria. The results indicate that microwell structures not only improve the spectral quality but also increase the reproducibility of the SERS spectra.

  9. Electron Raman scattering in a cylindrical quantum dot

    International Nuclear Information System (INIS)

    Zhong Qinghu; Yi Xuehua

    2012-01-01

    Electron Raman scattering (ERS) is investigated in a CdS cylindrical quantum dot (QD). The differential cross section is calculated as a function of the scattering frequency and the size of the QD. Single parabolic conduction and valence bands are assumed, and singularities in the spectrum are found and interpreted. The selection rules for the processes are also studied. The ERS studied here can be used to provide direct information about the electron band structure of these systems. (semiconductor physics)

  10. Surface-enhanced Raman scattering on gold nanotrenches and nanoholes

    KAUST Repository

    Yue, Weisheng; Yang, Yang; Wang, Zhihong; Chen, Longqing; Wong, Ka Chun; Syed, Ahad A.; Chen, Zong; Wang, Xianbin

    2012-01-01

    Dependent effects on edge-to-edge distance and incidence polarization in surface-enhanced Raman Scattering (SERS) were studied in detection of 4-mercaptopyridine (4-MPy) molecules absorbed on gold nanotrenches and nanoholes. The gold nanostructures

  11. Tip-Enhanced Raman Scattering Microscopy: A Step toward Nanoscale Control of Intrinsic Molecular Properties

    Science.gov (United States)

    Yano, Taka-aki; Hara, Masahiko

    2018-06-01

    Tip-enhanced Raman scattering microscopy, a family of scanning probe microscopy techniques, has been recognized as a powerful surface analytical technique with both single-molecule sensitivity and angstrom-scale spatial resolution. This review covers the current status of tip-enhanced Raman scattering microscopy in surface and material nanosciences, including a brief history, the basic principles, and applications for the nanoscale characterization of a variety of nanomaterials. The focus is on the recent trend of combining tip-enhanced Raman scattering microscopy with various external stimuli such as pressure, voltage, light, and temperature, which enables the local control of the molecular properties and functions and also enables chemical reactions to be induced on a nanometer scale.

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

    International Nuclear Information System (INIS)

    Volkmer, Andreas

    2005-01-01

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

  13. Raman Spectra of Nanodiamonds: New Treatment Procedure Directed for Improved Raman Signal Marker Detection

    Directory of Open Access Journals (Sweden)

    Raoul R. Nigmatullin

    2013-01-01

    Full Text Available Detonation nanodiamonds (NDs have shown to be promising agents in several industries, ranging from electronic to biomedical applications. These NDs are characterized by small particle size ranging from 3 to 6 nm, while having a reactive surface and a stable inert core. Nanodiamonds can exhibit novel intrinsic properties such as fluorescence, high refractive index, and unique Raman signal making them very attractive imaging agents. In this work, we used several nanodiamond preparations for Raman spectroscopic studies. We exposed these nanodiamonds to increasing temperature treatments at constant heating rates (425–575°C aiding graphite release. We wanted to correlate changes in the nanodiamond surface and properties with Raman signal which could be used as a detection marker. These observations would hold potential utility in biomedical imaging applications. First, the procedure of optimal linear smoothing was applied successfully to eliminate the high-frequency fluctuations and to extract the smoothed Raman spectra. After that we applied the secondary Fourier transform as the fitting function based on some significant set of frequencies. The remnant noise was described in terms of the beta-distribution function. We expect this data treatment to provide better results in biomolecule tracking using nanodiamond base Raman labeling.

  14. Development of a multiplexing fingerprint and high wavenumber Raman spectroscopy technique for real-time in vivo tissue Raman measurements at endoscopy

    Science.gov (United States)

    Bergholt, Mads Sylvest; Zheng, Wei; Huang, Zhiwei

    2013-03-01

    We report on the development of a novel multiplexing Raman spectroscopy technique using a single laser light together with a volume phase holographic (VPH) grating that simultaneously acquires both fingerprint (FP) and high wavenumber (HW) tissue Raman spectra at endoscopy. We utilize a customized VPH dual-transmission grating, which disperses the incident Raman scattered light vertically onto two separate segments (i.e., -150 to 1950 cm-1 1750 to 3600 cm-1) of a charge-coupled device camera. We demonstrate that the multiplexing Raman technique can acquire high quality in vivo tissue Raman spectra ranging from 800 to 3600 cm-1 within 1.0 s with a spectral resolution of 3 to 6 cm-1 during clinical endoscopy. The rapid multiplexing Raman spectroscopy technique covering both FP and HW ranges developed in this work has potential for improving in vivo tissue diagnosis and characterization at endoscopy.

  15. Rotational Raman scattering using molecular nitrogen gas for calibration of Thomson-scattering apparatus

    International Nuclear Information System (INIS)

    Yamauchi, Toshihiko; Nakazawa, Ichiro

    1987-01-01

    Anti-Stokes rotational Raman lines in molecular nitrogen gas were used for the calibration of Thomson-scattering apparatus. It was found that molecular nitrogen gas is suitable for a vessel having strong stray light. The polarization ratio was 0.16 using linear-polarized laser light. (author)

  16. Dynamic high pressure induced strong and weak hydrogen bonds enhanced by pre-resonance stimulated Raman scattering in liquid water.

    Science.gov (United States)

    Wang, Shenghan; Fang, Wenhui; Li, Fabing; Gong, Nan; Li, Zhanlong; Li, Zuowei; Sun, Chenglin; Men, Zhiwei

    2017-12-11

    355 nm pulsed laser is employed to excite pre-resonance forward stimulated Raman scattering (FSRS) of liquid water at ambient temperature. Due to the shockwave induced dynamic high pressure, the obtained Raman spectra begin to exhibit double peaks distribution at 3318 and 3373 cm -1 with the input energy of 17 mJ,which correspond with OH stretching vibration with strong and weak hydrogen (H) bonds. With laser energy rising from 17 to 27 mJ, the Stokes line at 3318 cm -1 shifts to 3255 and 3230 cm -1 because of the high pressure being enlarged. When the energy is up to 32 mJ, only 3373 cm -1 peak exists. The strong and weak H bond exhibit quite different energy dependent behaviors.

  17. MicroRaman scattering from polycrystalline CuInS{sub 2} films: structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Alvarez-Garcia, J.; Marcos-Ruzafa, J.; Perez-Rodriguez, A.; Romano-Rodriguez, A.; Morante, J.R. [Barcelona Univ. (Spain). Dept. de Fisica Aplicada i Electronica; Scheer, R. [Hahn-Meitner-Institut Berlin GmbH (Germany)

    2000-02-21

    CuInS{sub 2} thin films co-evaporated with gradual chemical composition have been characterised by microRaman scattering measurements. For the Cu rich region, the mode A{sub 1} at about 290 cm{sup -1} corresponding to the chalcopyrite phase is dominant. For the Cu poor region, this mode is accompanied by a strong contribution at about 306 cm{sup -1}. Besides, the mode A{sub 1} is broadened and shifted towards higher frequencies, which suggests an inferior structural quality of the Cu poor region. Decreasing the temperature of deposition leads to a dramatic decrease of structural quality in both In and Cu rich regions. The correlation between the appearance of the 306 cm{sup -1} mode and the spectral features of the mode A{sub 1} suggest the higher frequency mode is not related to the excess In in the layer but to structural effects as lattice disorder. Combined in-depth Auger electron spectroscopy and Raman scattering measurements have also shown the presence of a more complex structure for the Cu poor region of the layers, which presents a significant CuIn{sub 5}S{sub 8} secondary phase contribution in the spectra from the central region of the layers. The correlation of this contribution with the spectral features of the CuInS{sub 2} modes suggests a direct relationship between the presence of this In rich secondary phase and disorder at the CuInS{sub 2} lattice. (orig.)

  18. Effect of pressure on the second-order Raman scattering intensities of zincblende semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Trallero-Giner, C.; Syassen, K. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, 70569 Stuttgart (Germany)

    2010-01-15

    A microscopic description of the two-phonon scattering intensities in direct-gap zincblende-type semiconductors as a function of hydrostatic pressure and for non-resonant excitation is presented. The calculations were performed according to the electron-two-phonon deformation potential interaction for the {gamma}{sub 1} and {gamma}{sub 15} components of the Raman tensor. It is shown that the effect of pressure on the Raman scattering cross-section exhibits a complex behavior according to the contribution of the acoustical or optical phonons to the overtones and combinations. Second-order scattering intensities via acoustical modes could decrease or increase with increasing hydrostatic pressure, while for combinations or overtones of optical phonons a decreasing intensity is obtained. Calculations of the effect of pressure on second-order Raman intensities are compared to experimental results for ZnTe. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  19. Simulating Surface-Enhanced Hyper-Raman Scattering Using Atomistic Electrodynamics-Quantum Mechanical Models.

    Science.gov (United States)

    Hu, Zhongwei; Chulhai, Dhabih V; Jensen, Lasse

    2016-12-13

    Surface-enhanced hyper-Raman scattering (SEHRS) is the two-photon analogue of surface-enhanced Raman scattering (SERS), which has proven to be a powerful tool to study molecular structures and surface enhancements. However, few theoretical approaches to SEHRS exist and most neglect the atomistic descriptions of the metal surface and molecular resonance effects. In this work, we present two atomistic electrodynamics-quantum mechanical models to simulate SEHRS. The first is the discrete interaction model/quantum mechanical (DIM/QM) model, which combines an atomistic electrodynamics model of the nanoparticle with a time-dependent density functional theory description of the molecule. The second model is a dressed-tensors method that describes the molecule as a point-dipole and point-quadrupole object interacting with the enhanced local field and field-gradients (FG) from the nanoparticle. In both of these models, the resonance effects are treated efficiently by means of damped quadratic response theory. Using these methods, we simulate SEHRS spectra for benzene and pyridine. Our results show that the FG effects in SEHRS play an important role in determining both the surface selection rules and the enhancements. We find that FG effects are more important in SEHRS than in SERS. We also show that the spectral features of small molecules can be accurately described by accounting for the interactions between the molecule and the local field and FG of the nanoparticle. However, at short distances between the metal and molecule, we find significant differences in the SEHRS enhancements predicted using the DIM/QM and the dressed-tensors methods.

  20. In situ identification of paper chromatogram spots by surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Tran, C D

    1984-01-01

    The use of silver hydrosols to enhance the Raman scattering of paper chromatogram spots has been used successfully. This enhancement technique, which is dependent on the interaction between the substrate, silver particles, and paper fibers, has been applied to detection and identification of ng amounts of crystal violet, malachite green, and basic fuchsin with an argon laser of only 4 mW. This technique enhances the resonance of the Raman scattering so that the Raman cross sections of the spots are approximately 9 to 10 orders of magnitude higher than those observed for non-enhanced systems. The limit of detection of the techniques is defined as the amount of dye spot that yields a signal to noise ratio of 2 when excited with the 4MeV.

  1. Two-magnon Raman scattering in a Mott-Hubbard antiferromagnet

    International Nuclear Information System (INIS)

    Basu, S.; Singh, A.

    1996-01-01

    A perturbation-theoretic diagrammatic scheme is developed for systematically studying the two-magnon Raman scattering in a Mott-Hubbard antiferromagnet. The fermionic structure of the magnon interaction vertex is obtained at order-1/N level in an inverse-degeneracy expansion, and the relevant two-magnon propagator is obtained by incorporating magnon interactions at a ladder-sum level. Evaluation of the magnon interaction vertex in the large-U limit yields a nearest-neighbor instantaneous interaction with interaction energy -J. Application of this approach to the intermediate-U regime, which is of relevance for cuprate antiferromagnets, is also discussed. Incorporating the zero-temperature magnon damping, which is estimated in terms of quantum spin fluctuations, the two-magnon Raman scattering intensity is evaluated and compared with experiments on La 2 CuO 4 . copyright 1996 The American Physical Society

  2. Preliminary observations on differences in the Raman spectra of cancerous and noncancerous cells and connective tissue of human skin

    Science.gov (United States)

    Short, Michael A.; Lui, Harvey; McLean, David I.; Zeng, Haishan; Alajlan, Abdulmajeed; Chen, Michael X.

    2005-04-01

    A less invasive method of reliably detecting skin cancers is required. Raman spectroscopy is just one of several spectroscopic methods that look promising, but are not yet sufficiently reliable. More information is needed on how and why the Raman spectra of cancerous skin tissue is different from its normal counterpart. We have used confocal micro-Raman spectroscopy with a spatial resolution of about a micron to obtain spectra of unstained thin sections of human skin. We found that there were clear differences in the Raman spectra between cancerous and non-cancerous tissue both in cells and in the connective tissue. The DNA contribution to the spectra was generally stronger in malignant cells than normal ones. In regions of the dermis far away from the tumor one obtains the usual collagen spectra of normal skin, but adjacent to the tumor the spectra no longer appeared to be those of native collagen.

  3. IR, Raman and SERS studies of methyl salicylate

    Science.gov (United States)

    Varghese, Hema Tresa; Yohannan Panicker, C.; Philip, Daizy; Mannekutla, James R.; Inamdar, S. R.

    2007-04-01

    The IR and Raman spectra of methyl salicylate (MS) were recorded and analysed. Surface enhanced Raman scattering (SERS) spectrum was recorded in silver colloid. The vibrational wave numbers of the compound have been computed using the Hartree-Fock/6-31G * basis and compared with the experimental values. SERS studies suggest a flat orientation of the molecule at the metal surface.

  4. Enhanced Raman Scattering from NCM523 Cathodes Coated with Electrochemically Deposited Gold

    Energy Technology Data Exchange (ETDEWEB)

    Tornheim, Adam; Maroni, Victor A.; He, Meinan; Gosztola, David J.; Zhang, Zhengcheng

    2017-01-01

    Materials with the general composition LiMO2, where M is a mix of nickel, cobalt, and manganese, have been studied extensively as cathodes for lithium-based electrochemical cells. Some compositions, like LiNi0.5Co0.2Mn0.3O2 (NCM523), have already found application in commercial lithium-ion batteries. Pre-test and post-test analyses of these types of cathodes have benefited greatly from the use of Raman spectroscopy. Specifically, Raman spectroscopy can be used to investigate the phonons of the LiMO2 lattice. This is particularly useful for studies of the LiMO2 after it has been formed into the type of polymer-bonded laminate from which typical battery cathodes are cut. One of the problems that occurs in such studies is that the scattering from the LiMO2 phase gets progressively weaker as the nickel content increases. NCM523 poses one example of this behavior owing to the fact that half of the transition metal content is nickel. In this study we show that the intensity of the Raman scattering from the NCM523 phonons can be significantly increased by electroplating clusters of sub-micron gold particles on NCM523-containing laminate structures. The gold appears to plate somewhat selectively on the NCM523 particles in randomly sized clusters. These clusters stimulate the Raman scattering from the NCM523 to varying extents that can reach nearly 100 times the scattering intensity from uncoated pristine laminates.

  5. Instant detection and identification of concealed explosive-related compounds: Induced Stokes Raman versus infrared.

    Science.gov (United States)

    Elbasuney, Sherif; El-Sherif, Ashraf F

    2017-01-01

    The instant detection of explosives and explosive-related compounds has become an urgent priority in recent years for homeland security and counter-terrorism applications. Modern techniques should offer enhancement in selectivity, sensitivity, and standoff distances. Miniaturisation, portability, and field-ruggedisation are crucial requirements. This study reports on instant and standoff identification of concealed explosive-related compounds using customized Raman technique. Stokes Raman spectra of common explosive-related compounds were generated and spectrally resolved to create characteristic finger print spectra. The scattered Raman emissions over the band 400:2000cm -1 were compared to infrared absorption using FTIR. It has been demonstrated that the two vibrational spectroscopic techniques were opposite and completing each other. Molecular vibrations with strong absorption in infrared (those involve strong change in dipole moments) induced weak signals in Raman and vice versa. The tailored Raman offered instant detection, high sensitivity, and standoff detection capabilities. Raman demonstrated characteristic fingerprint spectra with stable baseline and sharp intense peaks. Complete correlations of absorption/scattered signals to certain molecular vibrations were conducted to generate an entire spectroscopic profile of explosive-related compounds. This manuscript shades the light on Raman as one of the prevailing technologies for instantaneous detection of explosive-related compounds. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  6. Raman spectra of Pm2O3, PmF3, PmCl3, PmBr3 and PmI3

    International Nuclear Information System (INIS)

    Wilmarth, W.R.; Peterson, J.R.

    1988-01-01

    Raman spectral data are presented for the sesquioxide and the trihalides (F, Cl, Br and I) of promethium. The Raman spectra of these lanthanide compounds are reported for the first time and are compared with those of the homologous lanthanide compounds. Tentative symmetry assignments have been made for the observed Raman-active bands based on factor group analysis of their respective crystal structures and comparisons with the assigned Raman spectra of other lanthanide compounds. The characteristic band patterns of the Raman phonon spectra have been found to be very useful in determining the crystal structure of the respective promethium compounds. (author)

  7. Raman spectra of ruthenium and tantalum trimers in argon matrices

    Science.gov (United States)

    Fang, Li; Shen, Xiaole; Chen, Xiaoyu; Lombardi, John R.

    2000-12-01

    The resonance Raman spectra of ruthenium trimers (Ru 3) in argon matrices have been obtained. Three resonance Raman transitions were observed between 570 and 590 nm. Two of them (303.4 and 603.7 cm -1) are assigned to the totally symmetric vibrational progression, giving k e=1.86 mdyne/ Å. The line at 581.5 cm-1 is assigned as the origin of a low-lying electronic state. We also report on the observation of a resonance Raman spectrum of tantalum trimers (Ta 3). Observed lines include 251.2 and 501.9 cm-1 which we assign to the fundamental and the first overtone of the symmetric stretch in Ta 3. This gives k e=2.25 mdyne/ Å.

  8. FT-IR, FT-Raman, UV spectra and DFT calculations on monomeric and dimeric structure of 2-amino-5-bromobenzoic acid.

    Science.gov (United States)

    Karabacak, Mehmet; Cinar, Mehmet

    2012-02-01

    In this work, the molecular conformation, vibrational and electronic transition analysis of 2-amino-5-bromobenzoic acid (2A5BrBA) were presented for the ground state using experimental techniques (FT-IR, FT-Raman and UV) and density functional theory (DFT) employing B3LYP exchange correlation with the 6-311++G(d,p) basis set. FT-IR and FT-Raman spectra were recorded in the regions of 400-4000 cm(-1) and 50-4000 cm(-1), respectively. There are four conformers, C1, C2, C3 and C4 for this molecule. The geometrical parameters, energies and wavenumbers have been obtained for all four conformers. The computational results diagnose the most stable conformer of 2A5BrBA as the C1 form. 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. Raman activities calculated by DFT method have been converted to the corresponding Raman intensities using Raman scattering theory. The UV spectra of investigated compound were recorded in the region of 200-400 nm for ethanol and water solutions. The electronic properties were evaluated with help of time-dependent DFT (TD-DFT) theoretically and results were compared with experimental observations. The thermodynamic properties of the studied compound at different temperatures were calculated, revealing the correlations between standard heat capacity, standard entropy, standard enthalpy changes and temperatures. The observed and the calculated geometric parameters, vibrational wavenumbers and electronic transitions were compared with observed data and found to be in good agreement. Copyright © 2011 Elsevier B.V. All rights reserved.

  9. Synthesis of Au Nanostars and Their Application as Surface Enhanced Raman Scattering-Activity Tags Inside Living Cells.

    Science.gov (United States)

    Cao, Xiaowei; Shi, Chaowen; Lu, Wenbo; Zhao, Hang; Wang, Man; Tong, Wei; Dong, Jian; Han, Xiaodong; Qian, Weiping

    2015-07-01

    This work presents the synthesis and characterization of Au nanostars (AuNSs) and demonstrates their application as surface enhanced Raman scattering (SERS)-activity tags for cellular imaging and sensing. Nile blue A (NBA) and bovine serum albumin (BSA) were used as Raman reporter molecules and capping materials, respectively. The SERS-activity tags were tested on human lung adenocarcinoma cell (A549) and alveolar type II cell (AT II) and found to present a low level of cytotoxicity and high chemical stability. These SERS-activity tags not only can be applied in multiplexed cellular imaging, including dark field imaging, transmission electron microscopy (TEM) and SERS imaging, but also can be used for cellular sensing. The SERS spectra clearly identified cellular important components such as proteins, nucleic acids, lipids, and carbohydrates. This study also shows that endocytosis is the main channel of tags internalized in cells. The AuNSs exhibiting strong surface enhanced Raman effects are utilized in the design of an efficient, stable SERS-activity tag for intracellular applications.

  10. Calculations of neutron spectra after neutron-neutron scattering

    Energy Technology Data Exchange (ETDEWEB)

    Crawford, B E [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Stephenson, S L [Gettysburg College, Box 405, Gettysburg, PA 17325 (United States); Howell, C R [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Mitchell, G E [North Carolina State University, Raleigh, NC 27695-8202 (United States); Tornow, W [Duke University and Triangle Universities Nuclear Laboratory, Durham, NC 27708-0308 (United States); Furman, W I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Lychagin, E V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Muzichka, A Yu [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Nekhaev, G V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Strelkov, A V [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Sharapov, E I [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation); Shvetsov, V N [Joint Institute for Nuclear Research, 141980 Dubna (Russian Federation)

    2004-09-01

    A direct neutron-neutron scattering length, a{sub nn}, measurement with the goal of 3% accuracy (0.5 fm) is under preparation at the aperiodic pulsed reactor YAGUAR. A direct measurement of a{sub nn} will not only help resolve conflicting results of a{sub nn} by indirect means, but also in comparison to the proton-proton scattering length, a{sub pp}, shed light on the charge-symmetry of the nuclear force. We discuss in detail the analysis of the nn-scattering data in terms of a simple analytical expression. We also discuss calibration measurements using the time-of-flight spectra of neutrons scattered on He and Ar gases and the neutron activation technique. In particular, we calculate the neutron velocity and time-of-flight spectra after scattering neutrons on neutrons and after scattering neutrons on He and Ar atoms for the proposed experimental geometry, using a realistic neutron flux spectrum-Maxwellian plus epithermal tail. The shape of the neutron spectrum after scattering is appreciably different from the initial spectrum, due to collisions between thermal-thermal and thermal-epithermal neutrons. At the same time, the integral over the Maxwellian part of the realistic scattering spectrum differs by only about 6 per cent from that of a pure Maxwellian nn-scattering spectrum.

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

    International Nuclear Information System (INIS)

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

    2007-01-01

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

  12. Enhanced Raman scattering on functionalized graphene substrates

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Kovaříček, Petr; Fridrichová, Michaela; Ji, X.; Ling, X.; Kong, J.; Dresselhaus, M. S.; Kalbáč, Martin

    2017-01-01

    Roč. 4, č. 2 (2017), č. článku 025087. ISSN 2053-1583 R&D Projects: GA ČR(CZ) GA15-01953S Grant - others:AVČR PPPLZ(CZ) L200401551 Institutional support: RVO:61388955 Keywords : spectroscopy * molecules * graphene * graphene enhanced Raman scattering * functionalized graphene Subject RIV: CF - Physical ; Theoretical Chemistry OBOR OECD: Physical chemistry Impact factor: 6.937, year: 2016

  13. Surface-enhanced Raman scattering biosensor for DNA detection on nanoparticle island substrates

    DEFF Research Database (Denmark)

    Yuan, Scott Wu; Ho, Ho Pui; Lee, Rebecca K.Y.

    2009-01-01

    We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree of repro......We present a study on the surface-enhanced Raman scattering (SERS) properties of Ag nanoparticle island substrates (NIS) and their applications for target oligonucleotide (OND) detection. It has been found that the surface nanostructure of NIS samples can be controlled with a good degree...

  14. Surface-Enhanced Raman Scattering in Molecular Junctions.

    Science.gov (United States)

    Iwane, Madoka; Fujii, Shintaro; Kiguchi, Manabu

    2017-08-18

    Surface-enhanced Raman scattering (SERS) is a surface-sensitive vibrational spectroscopy that allows Raman spectroscopy on a single molecular scale. Here, we present a review of SERS from molecular junctions, in which a single molecule or molecules are made to have contact from the top to the bottom of metal surfaces. The molecular junctions are nice platforms for SERS as well as transport measurement. Electronic characterization based on the transport measurements of molecular junctions has been extensively studied for the development of miniaturized electronic devices. Simultaneous SERS and transport measurement of the molecular junctions allow both structural (geometrical) and electronic information on the single molecule scale. The improvement of SERS measurement on molecular junctions open the door toward new nanoscience and nanotechnology in molecular electronics.

  15. The temporal evolution process from fluorescence bleaching to clean Raman spectra of single solid particles optically trapped in air

    Science.gov (United States)

    Gong, Zhiyong; Pan, Yong-Le; Videen, Gorden; Wang, Chuji

    2017-12-01

    We observe the entire temporal evolution process of fluorescence and Raman spectra of single solid particles optically trapped in air. The spectra initially contain strong fluorescence with weak Raman peaks, then the fluorescence was bleached within seconds, and finally only the clean Raman peaks remain. We construct an optical trap using two counter-propagating hollow beams, which is able to stably trap both absorbing and non-absorbing particles in air, for observing such temporal processes. This technique offers a new method to study dynamic changes in the fluorescence and Raman spectra from a single optically trapped particle in air.

  16. Normal state Raman spectra of high-Tc cuprates

    International Nuclear Information System (INIS)

    Bishoyi, K.C.; Rout, G.C.; Behera, S.N.

    2003-01-01

    We present a microscopic theory to explain Raman spectra of high-T c cuprates R 2-x M x CuO 4 in the normal state. We used electronic Hamiltonian prescribed by Fulde in presence of anti-ferromagnetism. Phonon interaction to the hybridization between the conduction electrons of the system and the f-electrons has been incorporated in the calculation. The phonon spectral density is calculated by the Green function technique of Zubarev at zero wave vector and finite (room) temperature limit. Parameter dependence of Raman active phonon frequencies are studied by varying model parameters of the system i.e. the position of f-level (ε f ), the effective electron-phonon coupling strength (g), the staggered magnetic field (h 1 ), and the hybridization parameter (v). The four Raman active peaks (P 1 to P 4 ) represent the electronic states of the atomic sub-systems of the cuprate systems. They show up as phonon excitations due to the coupling of the phonon to the electrons and the anti-ferromagnetic gap. (author)

  17. Theory of Two-Magnon Raman Scattering in Iron Pnictides and Chalcogenides

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C. C.

    2011-08-15

    Although the parent iron-based pnictides and chalcogenides are itinerant antiferromagnets, the use of local moment picture to understand their magnetic properties is still widespread. We study magnetic Raman scattering from a local moment perspective for various quantum spin models proposed for this new class of superconductors. These models vary greatly in the level of magnetic frustration and show a vastly different two-magnon Raman response. Light scattering by two-magnon excitations thus provides a robust and independent measure of the underlying spin interactions. In accord with other recent experiments, our results indicate that the amount of magnetic frustration in these systems may be small.

  18. Surface-enhanced Raman scattering active gold nanoparticle/nanohole arrays fabricated through electron beam lithography

    Science.gov (United States)

    Wu, Tsunghsueh; Lin, Yang-Wei

    2018-03-01

    Effective surface-enhanced Raman scattering (SERS)-active substrates from gold nanoparticle and gold nanohole arrays were successfully fabricated through electron beam lithography with precise computer-aided control of the unit size and intergap distance. Their SERS performance was evaluated using 4-mercaptobenzoic acid (4-MBA). These gold arrays yielded strong SERS signals under 785 nm laser excitation. The enhancement factors for 4-MBA molecules on the prepared gold nanoparticle and nanohole arrays maxed at 1.08 × 107 and 8.61 × 106, respectively. The observed increase in SERS enhancement was attributed to the localized surface plasmon resonance (LSPR) wavelength shifting toward the near-infrared regime when the gold nanohole diameter increased, in agreement with the theoretical prediction in this study. The contribution of LSPR to the Raman enhancement from nanohole arrays deposited on fluorine-doped tin oxide glass was elucidated by comparing SERS and transmission spectra. This simple fabrication procedure, which entails employing electron beam lithography and the controllability of the intergap distance, suggests highly promising uses of nanohole arrays as functional components in sensing and photonic devices.

  19. Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

    International Nuclear Information System (INIS)

    Raj, B.K.; Panda, S.K.; Rout, G.C.

    2013-01-01

    Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T C systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ c ± Δ s ). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy

  20. Microscopic theoretical study of Raman spectra in charge and spin ordered cuprate systems

    Energy Technology Data Exchange (ETDEWEB)

    Raj, B. K. [Dept. of Physics, Govt. Autonomous College, Angul, Orissa (India); Panda, S. K. [KD Science College, Pochilima, Hinjilicut, 761 101 Ganjam, Orissa (India); Rout, G.C., E-mail: gcr@iopb.res.in [Condensed Matter Physics Group, PG Dept. of Applied Physics and Ballistics, FM University, Balasore 756 019 (India)

    2013-09-15

    Highlights: • The model calculation treats CDW interaction as pseudogap for cuprates. • The interplay of Raman active CDW-SDW mixed modes are investigated. • Independent CDW and SDW gap values can be determined from experimental data. -- Abstract: Raman scattering is one of the most powerful methods to investigate the electron as well as the phonon excitations in the systems. In this communication, we present a theoretical study of Raman scattering in the normal state of the high-T{sub C} systems in the under-doped region displaying the interplay of the spin-density-wave (SDW) and charge-density-wave (CDW) interactions. The SDW order arises from the repulsive Coulomb interaction of electrons, while the CDW order arises due to strong electron–phonon interaction giving rise to Fermi surface instability. We calculate phonon response function in order to examine the possibility of observing the SDW excitation mode in presence of the CDW interaction present in the same conduction band. The Raman scattering intensity is calculated from the imaginary part of the phonon Green’s function assigning an arbitrary spectral width. The spectral density function displays two mixed modes of excitation peaks at energies 2(Δ{sub c} ± Δ{sub s}). The evolution of excitation peaks are investigated by varying CDW coupling, SDW coupling and the phonon momentum transfer energy.

  1. Influence of the ordered structure of short-chain polymer molecule all-trans-β-carotene on Raman scattering cross section in liquid

    International Nuclear Information System (INIS)

    Qu Guan-Nan; Li Zuo-Wei; Sun Cheng-Lin; Ou Yang Shun-Li; Wang Wei-Wei; Men Zhi-Wei

    2011-01-01

    We measured the resonant Raman spectra of all-trans-β-carotene in solvents with different densities and concentrations at different temperatures. The results demonstrated that the Raman scattering cross section (RSCS) of short-chain polymer all-trans-β-carotene is extremely high in liquid. Resonance and strong coherent weakly damped CC bond vibrating properties play important roles under these conditions. Coherent weakly damped CC bond vibration strength is associated with molecular ordered structure. All-trans-β-carotene has highly ordered structure and strong coherent weakly damped CC bond vibrating properties, which lead to large RSCS in the solvent with large density and low concentration at low temperature. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  2. Surface-enhanced Raman scattering reveals adsorption of mitoxantrone on plasma membrane of living cells

    International Nuclear Information System (INIS)

    Breuzard, G.; Angiboust, J.-F.; Jeannesson, P.; Manfait, M.; Millot, J.-M.

    2004-01-01

    Surface-enhanced Raman scattering (SERS) spectroscopy was applied to analyze mitoxantrone (MTX) adsorption on the plasma membrane microenvironment of sensitive (HCT-116 S) or BCRP/MXR-type resistant (HCT-116 R) cells. The addition of silver colloid to MTX-treated cells revealed an enhanced Raman scattering of MTX. Addition of extracellular DNA induced a total extinction of MTX Raman intensity for both cell lines, which revealed an adsorption of MTX on plasma membrane. A threefold higher MTX Raman intensity was observed for HCT-116 R, suggesting a tight MTX adsorption in the plasma membrane microenvironment. Fluorescence confocal microscopy confirmed a relative MTX emission around plasma membrane for HCT-116 R. After 30 min at 4 deg. C, a threefold decrease of the MTX Raman scattering was observed for HCT-116 R, contrary to HCT-116 S. Permeation with benzyl alcohol revealed a threefold decrease of membrane MTX adsorption on HCT-116 R, exclusively. This additional MTX adsorption should correspond to the drug bound to an unstable site on the HCT-116 R membrane. This study showed that SERS spectroscopy could be a direct method to reveal drug adsorption to the membrane environment of living cells

  3. Two-magnon Raman scattering in a spin density wave antiferromagnet

    OpenAIRE

    Schoenfeld, Friedhelm; Kampf, Arno P.; Mueller-Hartmann, Erwin

    1996-01-01

    We present the results for a model calculation of resonant two-magnon Raman scattering in a spin density wave (SDW) antiferromagnet. The resonant enhancement of the two-magnon intensity is obtained from a microscopic analysis of the photon-magnon coupling vertex. By combining magnon-magnon interactions with `triple resonance` phenomena in the vertex function the resulting intensity line shape is found to closely resemble the measured two-magnon Raman signal in antiferromagnetic cuprates. Both...

  4. Significant Contributions of the Albrecht's A Term to Nonresonant Raman Scattering Processes.

    Science.gov (United States)

    Gong, Zu-Yong; Tian, Guangjun; Duan, Sai; Luo, Yi

    2015-11-10

    The Raman intensity can be well described by the famous Albrecht's Raman theory that consists of A and B terms. It is well-known that the contribution from Albrecht's A term can be neglected without any loss of accuracy for far-off resonant Raman scattering processes. However, as demonstrated in this study, we have found that this widely accepted long-standing assumption fails drastically for totally symmetric vibration modes of molecules in general off-resonant Raman scattering. Perturbed first-principles calculations for water molecule show that strong constructive interference between the A and B terms occurs for the Raman intensity of the symmetric O-H stretching mode, which can account for ∼40% of the total intensity. Meanwhile, a minor destructive interference is found for the angle bending mode. The state-to-state mapping between Albrecht's theory and perturbation theory allows us to verify the accuracy of the widely employed perturbation method for the dynamic/resonant Raman intensities. The model calculations rationalized from water molecule with the bending mode show that the perturbation method is a good approximation only when the absolute energy difference between the first excited state and the incident light is more than five times greater than the vibrational energy in the ground state.

  5. A consideration of Raman scattering in the estimation of the background in low energy TXRF

    International Nuclear Information System (INIS)

    Doi, M.; Shoji, T.; Yamada, T.; Wilson, R.

    2000-01-01

    Accurate estimation of the background in a TXRF spectrum is necessary for trace analysis. The tailing of large peaks in the spectrum is the main source of the background. Sum and escape peaks are also part of the background caused from an SSD detector. Estimation and subtraction of these peaks from the spectrum have been successful with sophisticated software. Raman scattering is another possible phenomenon that will give rise to a background peak in the spectrum. This paper explores this Raman phenomenon. We used the W-Mα line for the low energy TXRF experiments. The W-Mα is effective for exciting aluminum, magnesium and sodium atoms. The energy of the W-Mα line, 1.78 keV, is above and near the absorption edges of these elements and yet below the absorption edge of silicon, 1.84 keV. To obtain a monochromatic W-Mα line, we used a monochromator consisting of a total reflection mirror of silicon and a crystal of RAP(001). The reflectivity of this monochromator is smaller than that of a monochromator consisting of synthesized multilayers but the energy resolution is superior. We measured the spectra from a blank silicon wafer and a silicon wafer covered with a titanium layer. A peak caused by the elastic scattering of the incident W-Mα line is the main peak that appeared at 1.78 keV in each spectrum. There is another peak at 1.65 keV in the spectrum from the blank wafer. The ratio of the intensity of this peak to that of the main peak increases with the glancing angle. The peak at 1.65 keV does not appear in the spectrum taken from a silicon wafer covered with a titanium layer. There are no characteristic x-rays which have this same energy. Also, Compton scattering cannot account for a peak at that energy. We calculated energies of diffracted x-rays by the silicon crystal assuming that x-rays having a continuous spectrum are included in the incident x-rays. However, there are no diffracted x-rays which have an energy in this range. The binding energy of

  6. Characterization and Discrimination of Gram-Positive Bacteria Using Raman Spectroscopy with the Aid of Principal Component Analysis

    Directory of Open Access Journals (Sweden)

    Alia Colniță

    2017-09-01

    Full Text Available Raman scattering and its particular effect, surface-enhanced Raman scattering (SERS, are whole-organism fingerprinting spectroscopic techniques that gain more and more popularity in bacterial detection. In this work, two relevant Gram-positive bacteria species, Lactobacillus casei (L. casei and Listeria monocytogenes (L. monocytogenes were characterized based on their Raman and SERS spectral fingerprints. The SERS spectra were used to identify the biochemical structures of the bacterial cell wall. Two synthesis methods of the SERS-active nanomaterials were used and the recorded spectra were analyzed. L. casei and L. monocytogenes were successfully discriminated by applying Principal Component Analysis (PCA to their specific spectral data.

  7. Rational design of Raman-labeled nanoparticles for a dual-modality, light scattering immunoassay on a polystyrene substrate.

    Science.gov (United States)

    Israelsen, Nathan D; Wooley, Donald; Hanson, Cynthia; Vargis, Elizabeth

    2016-01-01

    Surface-enhanced Raman scattering (SERS) is a powerful light scattering technique that can be used for sensitive immunoassay development and cell labeling. A major obstacle to using SERS is the complexity of fabricating SERS probes since they require nanoscale characterization and optical uniformity. The light scattering response of SERS probes may also be modulated by the substrate used for SERS analysis. A typical SERS substrate such as quartz can be expensive. Polystyrene is a cheaper substrate option but can decrease the SERS response due to interfering Raman emission peaks and high background fluorescence. The goal of this research is to develop an optimized process for fabricating Raman-labeled nanoparticles for a SERS-based immunoassay on a polystyrene substrate. We have developed a method for fabricating SERS nanoparticle probes for use in a light scattering immunoassay on a polystyrene substrate. The light scattering profile of both spherical gold nanoparticle and gold nanorod SERS probes were characterized using Raman spectroscopy and optical absorbance spectroscopy. The effects of substrate interference and autofluorescence were reduced by selecting a Raman reporter with a strong light scattering response in a spectral region where interfering substrate emission peaks are minimized. Both spherical gold nanoparticles and gold nanorods SERS probes used in the immunoassay were detected at labeling concentrations in the low pM range. This analytical sensitivity falls within the typical dynamic range for direct labeling of cell-surface biomarkers using SERS probes. SERS nanoparticle probes were fabricated to produce a strong light scattering signal despite substrate interference. The optical extinction and inelastic light scattering of these probes was detected by optical absorbance spectroscopy and Raman spectroscopy, respectively. This immunoassay demonstrates the feasibility of analyzing strongly enhanced Raman signals on polystyrene, which is an

  8. Calculated shape dependence of electromagnetic field in tip-enhanced Raman scattering by using a monopole antenna model

    Science.gov (United States)

    Kitahama, Yasutaka; Itoh, Tamitake; Suzuki, Toshiaki

    2018-05-01

    To evaluate the shape of an Ag tip with regard to tip-enhanced Raman scattering (TERS) signal, the enhanced electromagnetic (EM) field and scattering spectrum, arising from surface plasmon resonance at the apex of the tip, were calculated using a finite-difference time domain (FDTD) method. In the calculated forward scattering spectra from the smooth Ag tip, the band appeared within the visible region, similar to the experimental results and calculation for a corrugated Ag cone. In the FDTD calculation of TERS, the Ag tip acting as a monopole antenna was adopted by insertion of a perfect electric conductor between the root of the tip and a top boundary surface of the calculation space. As a result, the EM field was only enhanced at the apex. The shape dependence i.e. the EM field calculated at the apex with various curvatures on the different tapered tips, obtained using the monopole antenna model, was different from that simulated using a conventional dipole antenna model.

  9. Surface-Enhanced Raman Scattering of Bacteria in Micro wells Constructed from Silver Nanoparticles

    International Nuclear Information System (INIS)

    Culha, M.; Yazici, M.M.; Kahraman, M.; Sahin, F.; Sesin Kocagoz, S.

    2012-01-01

    Whole bacterial cell characterization is critically important for fast bacterial identification. Surface-enhanced Raman scattering (SERS) is proven to be powerful technique to serve such a goal. In this study, the characterization of whole bacterial cells in the micro wells constructed from colloidal silver nanoparticles (AgNPs) with convective-assembly method is reported.- The proper size of the micro wells for the model bacteria, Escherichia coli and Staphylococcus cohnii, is determined to be 1.2μm from their electron microscopy images. A minimum dilution factor of 20 is necessary for the bacterial samples collected from growth media to diminish the bacterial aggregation to place the bacterial cells into the micro wells. The constructed micro well structures are tested for their bacterial SERS performance and compared to the SERS spectra obtained from the samples prepared with a simple mixing of bacteria and AgNPs for the same bacteria. The results indicate that micro well structures not only improve the spectral quality but also increase the reproducibility of the SERS spectra.

  10. Charged defects in chalcogenide vitreous semiconductors studied with combined Raman scattering and PALS methods

    International Nuclear Information System (INIS)

    Kavetskyy, T.; Vakiv, M.; Shpotyuk, O.

    2007-01-01

    A combination of Raman scattering and positron annihilation lifetime spectroscopy (PALS) techniques to study charged defects in chalcogenide vitreous semiconductors (ChVSs) was applied for the first time in this study. In the case of Ge 15.8 As 21 S 63.2 glass, it is found that the main radiation-induced switching of heteropolar Ge-S bonds into heteropolar As-S ones, previously detected by IR fast Fourier transform spectroscopy, can also be identified by Raman spectroscopy in the depolarized configuration. Results obtained by Raman scattering are in good agreement with PALS data for the investigated glass composition

  11. Charged defects in chalcogenide vitreous semiconductors studied with combined Raman scattering and PALS methods

    Energy Technology Data Exchange (ETDEWEB)

    Kavetskyy, T.; Vakiv, M. [Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine); Shpotyuk, O. [Lviv Institute of Materials of SRC ' Carat' , 202 Stryjska str., Lviv, UA-79031 (Ukraine)], E-mail: shpotyuk@novas.lviv.ua

    2007-04-15

    A combination of Raman scattering and positron annihilation lifetime spectroscopy (PALS) techniques to study charged defects in chalcogenide vitreous semiconductors (ChVSs) was applied for the first time in this study. In the case of Ge{sub 15.8}As{sub 21}S{sub 63.2} glass, it is found that the main radiation-induced switching of heteropolar Ge-S bonds into heteropolar As-S ones, previously detected by IR fast Fourier transform spectroscopy, can also be identified by Raman spectroscopy in the depolarized configuration. Results obtained by Raman scattering are in good agreement with PALS data for the investigated glass composition.

  12. Effects of the ohmic current on collective scattering spectra

    International Nuclear Information System (INIS)

    Castiglioni, S.; Lontano, M.; Tartari, U.

    1993-01-01

    A numerical and analytical study of the modifications induced in the collective scattering spectra by the ohmic current governing the equilibrium magnetic configuration in toroidal plasmas is presented. The spectral density function is calculated assuming equilibrium distributions for the (bulk and impurity) ion species and a Spitzer-like distribution to describe the response of the electrons to the applied DC electric field. As expected, the spectral asymmetries can be non-negligibly enhanced in the region of the ion-acoustic frequency. They reach their maxima for tangential scattering geometries, where the magnetic effects on the spectra are negligible. This justifies the assumption of the non-magnetized spectra. A theoretically motivated potential is shown to exist for a more detailed experimental investigation of the feasibility of current-density measurements in ohmic plasmas, based on collective scattering. (author)

  13. Silver nanoparticle based surface enhanced Raman scattering spectroscopy of diabetic and normal rat pancreatic tissue under near-infrared laser excitation

    International Nuclear Information System (INIS)

    Huang, H; Shi, H; Chen, W; Yu, Y; Lin, D; Xu, Q; Feng, S; Lin, J; Huang, Z; Li, Y; Chen, R

    2013-01-01

    This paper presents the use of high spatial resolution silver nanoparticle based near-infrared surface enhanced Raman scattering (SERS) from rat pancreatic tissue to obtain biochrmical information about the tissue. A high quality SERS signal from a mixture of pancreatic tissues and silver nanoparticles can be obtained within 10 s using a Renishaw micro-Raman system. Prominent SERS bands of pancreatic tissue were assigned to known molecular vibrations, such as the vibrations of DNA bases, RNA bases, proteins and lipids. Different tissue structures of diabetic and normal rat pancreatic tissues have characteristic features in SERS spectra. This exploratory study demonstrated great potential for using SERS imaging to distinguish diabetic and normal pancreatic tissues on frozen sections without using dye labeling of functionalized binding sites. (letter)

  14. Time-dependent density functional methods for Raman spectra in open-shell systems.

    Science.gov (United States)

    Aquino, Fredy W; Schatz, George C

    2014-01-16

    We present an implementation of a time-dependent density functional theory (TD-DFT) linear response module in NWChem for unrestricted DFT calculations and apply it to the calculation of resonant Raman spectra in open-shell molecular systems using the short-time approximation. The new source code was validated and applied to simulate Raman spectra on several doublet organic radicals (e.g., benzyl, benzosemiquinone, TMPD, trans-stilbene anion and cation, and methyl viologen) and the metal complex copper phthalocyanine. We also introduce a divide-and-conquer approach for the evaluation of polarizabilities in relatively large systems (e.g., copper phthalocyanine). The implemented tool gives comparisons with experiment that are similar to what is commonly found for closed-shell systems, with good agreement for most features except for small frequency shifts, and occasionally large deviations for some modes that depend on the molecular system studied, experimental conditions not being accounted in the modeling such as solvation effects and extra solvent-based peaks, and approximations in the underlying theory. The approximations used in the quantum chemical modeling include (i) choice of exchange-correlation functional and basis set; (ii) harmonic approximation used in the frequency analysis to determine vibrational normal modes; and (iii) short-time approximation (omission of nuclear motion effects) used in calculating resonant Raman spectra.

  15. Probing edge-activated resonant Raman scattering from mechanically exfoliated 2D MoO3 nanolayers

    International Nuclear Information System (INIS)

    Yano, Taka-aki; Yoshida, Keisuke; Hayashi, Tomohiro; Hara, Masahiko; Hayamizu, Yuhei; Ohuchi, Fumio

    2015-01-01

    We report spatially resolved vibrational analysis of mechanically exfoliated single-crystalline α-MoO 3 nanolayers. Raman scattering from α-MoO 3 was enhanced predominantly at the outside edges of the nanolayers. The enhanced Raman scattering at the edges was attributed primarily to the enhanced resonant Raman effect caused by a high density of oxygen vacancies localized at the edges. The localized vacancy sites corresponded to a non-stoichiometric phase of MoO 3 , which would provide reactive sites with high catalytic activity. (paper)

  16. Label-free cellular imaging by broadband coherent anti-Stokes Raman scattering microscopy.

    Science.gov (United States)

    Parekh, Sapun H; Lee, Young Jong; Aamer, Khaled A; Cicerone, Marcus T

    2010-10-20

    Raman microspectroscopy can provide the chemical contrast needed to characterize the complex intracellular environment and macromolecular organization in cells without exogenous labels. It has shown a remarkable ability to detect chemical changes underlying cell differentiation and pathology-related chemical changes in tissues but has not been widely adopted for imaging, largely due to low signal levels. Broadband coherent anti-Stokes Raman scattering (B-CARS) offers the same inherent chemical contrast as spontaneous Raman but with increased acquisition rates. To date, however, only spectrally resolved signals from the strong CH-related vibrations have been used for CARS imaging. Here, we obtain Raman spectral images of single cells with a spectral range of 600-3200 cm⁻¹, including signatures from weakly scattering modes as well as CH vibrations. We also show that B-CARS imaging can be used to measure spectral signatures of individual cells at least fivefold faster than spontaneous Raman microspectroscopy and can be used to generate maps of biochemical species in cells. This improved spectral range and signal intensity opens the door for more widespread use of vibrational spectroscopic imaging in biology and clinical diagnostics. Copyright © 2010 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  17. Collective vibrational spectra of α- and γ-glycine studied by terahertz and Raman spectroscopy

    International Nuclear Information System (INIS)

    Shi Yulei; Wang Li

    2005-01-01

    Terahertz time-domain spectroscopy is used to investigate the absorption and dispersion of polycrystalline α- and γ-glycine in the spectral region 0.5-3.0 THz. The spectra exhibit distinct features in these two crystalline phases. The observed far-infrared responses are attributed to intermolecular vibrational modes mediated by hydrogen bonds. We also measure the Raman spectra of the polycrystalline and dissolved glycine in the frequency range 28-3900 cm -1 . The results show that all the vibrational modes below 200 cm -1 are nonlocalized but are of a collective (phonon-like) nature. Furthermore, the temperature dependence of the Raman spectra of α-glycine agrees with the anharmonicity mechanism of the vibrational potentials

  18. Observation of Electronic Raman Scattering in Metallic Carbon Nanotubes

    Czech Academy of Sciences Publication Activity Database

    Farhat, H.; Berciaud, S.; Kalbáč, Martin; Saito, R.; Heinz, T. F.; Dresselhaus, M. S.; Kong, J.

    2011-01-01

    Roč. 107, č. 15 (2011), s. 157401 ISSN 0031-9007 R&D Projects: GA MŠk ME09060 Institutional research plan: CEZ:AV0Z40400503 Keywords : spectroscopy * electronic Raman scattering * metallic carbon nanotubes Subject RIV: CG - Electrochemistry Impact factor: 7.370, year: 2011

  19. Discriminating model for diagnosis of basal cell carcinoma and melanoma in vitro based on the Raman spectra of selected biochemicals

    Science.gov (United States)

    Silveira, Landulfo; Silveira, Fabrício Luiz; Bodanese, Benito; Zângaro, Renato Amaro; Pacheco, Marcos Tadeu T.

    2012-07-01

    Raman spectroscopy has been employed to identify differences in the biochemical constitution of malignant [basal cell carcinoma (BCC) and melanoma (MEL)] cells compared to normal skin tissues, with the goal of skin cancer diagnosis. We collected Raman spectra from compounds such as proteins, lipids, and nucleic acids, which are expected to be represented in human skin spectra, and developed a linear least-squares fitting model to estimate the contributions of these compounds to the tissue spectra. We used a set of 145 spectra from biopsy fragments of normal (30 spectra), BCC (96 spectra), and MEL (19 spectra) skin tissues, collected using a near-infrared Raman spectrometer (830 nm, 50 to 200 mW, and 20 s exposure time) coupled to a Raman probe. We applied the best-fitting model to the spectra of biochemicals and tissues, hypothesizing that the relative spectral contribution of each compound to the tissue Raman spectrum changes according to the disease. We verified that actin, collagen, elastin, and triolein were the most important biochemicals representing the spectral features of skin tissues. A classification model applied to the relative contribution of collagen III, elastin, and melanin using Euclidean distance as a discriminator could differentiate normal from BCC and MEL.

  20. Kernel principal component analysis residual diagnosis (KPCARD): An automated method for cosmic ray artifact removal in Raman spectra

    International Nuclear Information System (INIS)

    Li, Boyan; Calvet, Amandine; Casamayou-Boucau, Yannick; Ryder, Alan G.

    2016-01-01

    A new, fully automated, rapid method, referred to as kernel principal component analysis residual diagnosis (KPCARD), is proposed for removing cosmic ray artifacts (CRAs) in Raman spectra, and in particular for large Raman imaging datasets. KPCARD identifies CRAs via a statistical analysis of the residuals obtained at each wavenumber in the spectra. The method utilizes the stochastic nature of CRAs; therefore, the most significant components in principal component analysis (PCA) of large numbers of Raman spectra should not contain any CRAs. The process worked by first implementing kernel PCA (kPCA) on all the Raman mapping data and second accurately estimating the inter- and intra-spectrum noise to generate two threshold values. CRA identification was then achieved by using the threshold values to evaluate the residuals for each spectrum and assess if a CRA was present. CRA correction was achieved by spectral replacement where, the nearest neighbor (NN) spectrum, most spectroscopically similar to the CRA contaminated spectrum and principal components (PCs) obtained by kPCA were both used to generate a robust, best curve fit to the CRA contaminated spectrum. This best fit spectrum then replaced the CRA contaminated spectrum in the dataset. KPCARD efficacy was demonstrated by using simulated data and real Raman spectra collected from solid-state materials. The results showed that KPCARD was fast ( 1 million) Raman datasets. - Highlights: • New rapid, automatable method for cosmic ray artifact correction of Raman spectra. • Uses combination of kernel PCA and noise estimation for artifact identification. • Implements a best fit spectrum replacement correction approach.

  1. Raman spectroscopy in graphene

    International Nuclear Information System (INIS)

    Malard, L.M.; Pimenta, M.A.; Dresselhaus, G.; Dresselhaus, M.S.

    2009-01-01

    Recent Raman scattering studies in different types of graphene samples are reviewed here. We first discuss the first-order and the double resonance Raman scattering mechanisms in graphene, which give rise to the most prominent Raman features. The determination of the number of layers in few-layer graphene is discussed, giving special emphasis to the possibility of using Raman spectroscopy to distinguish a monolayer from few-layer graphene stacked in the Bernal (AB) configuration. Different types of graphene samples produced both by exfoliation and using epitaxial methods are described and their Raman spectra are compared with those of 3D crystalline graphite and turbostratic graphite, in which the layers are stacked with rotational disorder. We show that Resonance Raman studies, where the energy of the excitation laser line can be tuned continuously, can be used to probe electrons and phonons near the Dirac point of graphene and, in particular allowing a determination to be made of the tight-binding parameters for bilayer graphene. The special process of electron-phonon interaction that renormalizes the phonon energy giving rise to the Kohn anomaly is discussed, and is illustrated by gated experiments where the position of the Fermi level can be changed experimentally. Finally, we discuss the ability of distinguishing armchair and zig-zag edges by Raman spectroscopy and studies in graphene nanoribbons in which the Raman signal is enhanced due to resonance with singularities in the density of electronic states.

  2. Raman study of ? crystals

    Science.gov (United States)

    Pimenta, M. A.; Oliveira, M. A. S.; Bourson, P.; Crettez, J. M.

    1997-09-01

    In this work we present a polarized Raman study of 0953-8984/9/37/020/img7 single crystals for several values of the concentration 0953-8984/9/37/020/img8 made using different scattering geometries. The Raman spectra, composed of broad bands, have been fitted in accordance with a symmetry analysis which allowed us to assign the vibrational modes, and determine their frequencies and damping constants. The results are compatible with an average hexagonal symmetry for the solid solutions with x in the range 0953-8984/9/37/020/img9. In each of the spectra we found two bands at about 590 and 0953-8984/9/37/020/img10, probably associated with the existence of 0953-8984/9/37/020/img11 structures in the solid solutions.

  3. Raman spectra of zirconium tetrachloride in molten and evaporational states

    International Nuclear Information System (INIS)

    Salyuev, A.B.; Kornyakova, I.D.

    1994-01-01

    For the first time raman spectra of ZrCl 4 are obtained in the temperature range of its existence in molten state as well as in vapors near the critical point. It is shown, that rupture of zigzag chains is taking place when ZrCl 4 is melting

  4. Laser Raman and resonance Raman spectroscopies of natural semiconductor mineral cinnabar, α-HgS, from various mines

    International Nuclear Information System (INIS)

    Gotoshia, Sergo V; Gotoshia, Lamara V

    2008-01-01

    Natural minerals α-HgS from various mines have been studied by laser Raman spectroscopy and resonance Raman spectroscopy. The crystals differ from each other in the content of selenium impurity, included in samples from some mines. Based on the Raman spectra and the factor-group analysis the classification of the first order phonons and then the comparison of the results with the results from other works were carried out. The Raman spectra analysis of minerals from various mines show the selenium impurity gap vibration at 203 cm -1 and 226 cm -1 frequencies, respectively. On the basis of statistical measurements of the Raman spectra one can conclude that impurity frequencies of α-HgS may be generally used for the identification of the mine. Resonance Raman scattering for pure minerals has been studied by a dye laser. Phonon resonance in the indirect semiconductor α-HgS is found to be far more intense than the indirect resonance detected until now in various semiconductors in the proximity of the first indirect band E g , for instance, in GaP. In our opinion, this may be conditioned by cinnabar band structure peculiarities. Low resonance has also been fixed in 'dirty' minerals at the spectral band frequency of 203 cm -1 characterizing gap vibration of isomorphic impurity Se in cinnabar

  5. Radiative transfer equation accounting for rotational Raman scattering and its solution by the discrete-ordinates method

    International Nuclear Information System (INIS)

    Rozanov, Vladimir V.; Vountas, Marco

    2014-01-01

    Rotational Raman scattering of solar light in Earth's atmosphere leads to the filling-in of Fraunhofer and telluric lines observed in the reflected spectrum. The phenomenological derivation of the inelastic radiative transfer equation including rotational Raman scattering is presented. The different forms of the approximate radiative transfer equation with first-order rotational Raman scattering terms are obtained employing the Cabannes, Rayleigh, and Cabannes–Rayleigh scattering models. The solution of these equations is considered in the framework of the discrete-ordinates method using rigorous and approximate approaches to derive particular integrals. An alternative forward-adjoint technique is suggested as well. A detailed description of the model including the exact spectral matching and a binning scheme that significantly speeds up the calculations is given. The considered solution techniques are implemented in the radiative transfer software package SCIATRAN and a specified benchmark setup is presented to enable readers to compare with own results transparently. -- Highlights: • We derived the radiative transfer equation accounting for rotational Raman scattering. • Different approximate radiative transfer approaches with first order scattering were used. • Rigorous and approximate approaches are shown to derive particular integrals. • An alternative forward-adjoint technique is suggested as well. • An additional spectral binning scheme which speeds up the calculations is presented

  6. The use of Raman scattering for studying the defects created by implantation in semiconductors

    International Nuclear Information System (INIS)

    Morhange, J.F.; Beserman, R.; Bourgoin, J.

    1974-01-01

    The evolution of Raman scattering with the dose of implanted ions and annealing temperature in silicon and diamond was studied. The variation in the concentration of the defects introduced by implantation, with the dose and annealing temperature were deduced. These results were compared with results obtained using electron paramagnetic resonance. The comparison shows that Raman scattering is a good technique to study the behavior of the defects in ion implanted semiconductors [fr

  7. The use of lasers as sources for Raman spectrometry, resonance Raman spectrometry, and light scattering

    International Nuclear Information System (INIS)

    Capitini, R.; Ceccaldi, M.; Leicknam, J.P.; Plus, R.

    1975-01-01

    The activity of the laboratory is principally centred on the determination of molecular structures and the study of molecular interactions in solution by infrared and Raman spectrometry. With the development of work on relatively large molecules, particularly biological molecules, it became necessary to complete information on the molecular weight and on the intra and intermolecular geometry and interactions of these bodies. In order to obtain these informations Rayleigh scattering and resonance Raman spectrometry were used. The advantages of using vibrational spectrometry, particularly Raman, in conjunction with the diffusion of light for these structural and molecular interaction studies is emphasized. It is shown that these two techniques could not have developed as they have done in the last few years without the use of lasers as light source [fr

  8. Surface-enhanced Raman scattering of dipolar molecules by the graphene Fermi surface modulation with different dipole moments

    Science.gov (United States)

    Zhang, Mingjia; Leng, Yandan; Huang, Jing; Yu, JiaoJiao; Lan, Zhenggang; Huang, Changshui

    2017-12-01

    We report the modulation of Raman scattering spectrum of chromophore/graphene hybrids by tunning the molecular polarization with different terminal groups (methyl, methoxy, nitrile, and two nitros). Based on the density functional theory, the specific dipole moment values of the chromophore molecules are calculated. An obvious surface-enhanced Raman scattering (SERS) was observed and the scattering intensity of molecule increases with enlarged dipole moment. According to the analysis of G band Raman shifts of graphene, the enhancement of the Raman signal can be attributed to strong electronic coupling between graphene and chromophore, which is closely related with the modulation of graphene Fermi surface by changing the dipole moment of the molecule. Besides, the optimization of the ground state geometry and the binding energy of the hybrids were also calculated with the Density Functional Based Tight Bonding (DFTB) method, which confirms that the enhanced Raman scattering of molecules on graphene arises from the improved energy level matching between graphene Fermi surface and molecular band, further providing a new way to design novel SERS devices.

  9. Raman scattering from epitaxial HfN layers grown on MgO(001)

    International Nuclear Information System (INIS)

    Stoehr, M.; Seo, H.-S.; Petrov, I.; Greene, J.E.

    2006-01-01

    Stoichiometric single-crystal HfN layers grown on MgO(001) are analyzed by Raman spectroscopy. Second-order Raman scattering predominates, but first-order modes in the acoustic and optical ranges are also visible. The latter indicates that the O h symmetry of NaCl-structure HfN is broken. The large mass difference between Hf and N leads to a correspondingly large separation, 250 cm -1 , between the first-order acoustic and optical bands. Within this gap, four Raman lines are clearly observed. The first three are the second-order transverse acoustic mode (240 cm -1 ), the sum of the first-order transverse and longitudinal acoustic modes (280 cm -1 ), and the second-order longitudinal acoustic mode (325 cm -1 ). The fourth line at 380 cm -1 is identified as the difference between the first-order optical and acoustic modes. The observed first-order Raman scattering, as well as the width of the gap between the first-order acoustic and optical modes, is in good agreement with previously calculated HfN phonon density of states

  10. Quick detection of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces by surface-enhanced Raman spectroscopy

    Science.gov (United States)

    Huang, Hao; Shi, Hong; Feng, Shangyuan; Lin, Juqiang; Chen, Weiwei; Yu, Yun; Lin, Duo; Xu, Qian; Chen, Rong

    2013-01-01

    A surface-enhanced Raman spectroscopy (SERS) method was developed for the analysis of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces (AMRP) for the first time with the aim to develop a quick method for traditional Chinese medicine detection. Both Raman spectra and SERS spectra were obtained from AMRP, and tentative assignments of the Raman bands in the measured spectra suggested that only a few weak Raman peaks could be observed in the regular Raman spectra, while primary Raman peaks at around 536, 555, 619, 648, 691, 733, 790, 958, 1004, 1031, 1112, 1244, 1324, 1395, 1469, 1574 and 1632 cm-1 could be observed in the SERS spectra, with the strongest signals at 619, 733, 958, 1324, 1395 and 1469 cm-1. This was due to a strong interaction between the silver colloids and the AMRP, which led to an extraordinary enhancement in the intensity of the Raman scattering in AMRP. This exploratory study suggests the SERS technique has great potential for providing a novel non-destructive method for effectively and accurately detecting traditional Chinese medicine without complicated separation and extraction.

  11. Optically controlled seeding of Raman forward scattering and injection of electrons in a self-modulated laser-wakefield accelerator

    International Nuclear Information System (INIS)

    Chen, W.-T.; Chien, T.-Y.; Lee, C.-H.; Lin, J.-Y.; Wang, J.; Chen, S.-Y.

    2004-01-01

    Optical seeding of plasma waves and the injection of electrons are key issues in self-modulated laser-wakefield accelerators. By implementing a copropagating laser prepulse with proper timing, we are able to control the growth of Raman forward scattering and the production of accelerated electrons. The dependence of the Raman intensity on prepulse timing indicates that the seeding of Raman forward scattering is dominated by the ionization-induced wakefield, and the dependence of the divergence and number of accelerated electrons further reveals that the stimulated Raman backward scattering of the prepulse plays the essential role of injecting hot electrons into the fast plasma wave driven by the main pulse

  12. Hyper-Rayleigh scattering and hyper-Raman scattering of dye-adsorbed silver nanoparticles induced by a focused continuous-wave near-infrared laser

    International Nuclear Information System (INIS)

    Itoh, Tamitake; Ozaki, Yukihiro; Yoshikawa, Hiroyuki; Ihama, Takashi; Masuhara, Hiroshi

    2006-01-01

    We report that hyper-Rayleigh scattering, surface-enhanced hyper-Raman scattering, and two-photon excited luminescence occur intermittently by focusing a continuous-wave near-infrared (cw-NIR) laser into a colloidal silver solution including rhodamine 6G (R6G) and sodium chloride (NaCl). On the other hand, continuous hyper-Rayleigh scattering is observed from colloidal silver free from R6G and NaCl, demonstrating that hyper-Raman scattering and two-photon excited luminescence are attributed to R6G and their intermittent features are dependent on the colloidal dispersion. These results suggest that the cw-NIR laser has three roles; the source of the nonlinear response, optical trapping of nanoparticles, and making nanoparticle aggregates possessing the high activity for the nonlinear response

  13. Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions

    Czech Academy of Sciences Publication Activity Database

    Daněček, Petr; Kapitán, Josef; Baumruk, V.; Bednárová, Lucie; Kopecký, V.; Bouř, Petr

    2007-01-01

    Roč. 126, č. 22 (2007), s. 224513-1 ISSN 0021-9606 R&D Projects: GA ČR GA203/06/0420; GA ČR GA202/07/0732; GA AV ČR IAA400550702 Institutional research plan: CEZ:AV0Z40550506 Keywords : IR * Raman * ROA spectra * Anharmonic effects Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.044, year: 2007

  14. Templated green synthesis of plasmonic silver nanoparticles in onion epidermal cells suitable for surface-enhanced Raman and hyper-Raman scattering

    DEFF Research Database (Denmark)

    Palanco, Marta Espina; Mogensen, Klaus Bo; Guehlke, Marina

    2016-01-01

    We report fast and simple green synthesis of plasmonic silver nanoparticles in the epidermal cells of onions after incubation with AgNO3 solution. The biological environment supports the generation of silver nanostructures in two ways. The plant tissue delivers reducing chemicals for the initial...... for one-and two-photon-excited spectroscopy such as surface enhanced Raman scattering (SERS) and surface enhanced hyper-Raman scattering (SEHRS). Our studies demonstrate a templated green preparation of enhancing plasmonic nanoparticles and suggest a new route to deliver silver nanoparticles as basic...... building blocks of plasmonic nanosensors to plants by the uptake of solutions of metal salts....

  15. Reversibility of Graphene-Enhanced Raman Scattering with Fluorinated Graphene

    Czech Academy of Sciences Publication Activity Database

    Valeš, Václav; Melníková Komínková, Zuzana; Verhagen, Timotheus; Vejpravová, Jana; Kalbáč, Martin

    2017-01-01

    Roč. 254, č. 11 (2017), č. článku 1700177. ISSN 0370-1972 R&D Projects: GA ČR(CZ) GA15-01953S; GA MŠk(CZ) LM2015073 Grant - others:GA MŠk(CZ) CZ.02.1.01/0.0/0.0/16_013/0001821 Institutional support: RVO:61388955 ; RVO:68378271 Keywords : fluorination * graphene * graphene-enhanced Raman * Raman spectroscopy * scattering Subject RIV: CF - Physical ; Theoretical Chemistry; BM - Solid Matter Physics ; Magnetism (FZU-D) OBOR OECD: Physical chemistry; Condensed matter physics (including formerly solid state physics, supercond.) (FZU-D) Impact factor: 1.674, year: 2016

  16. Using Raman Spectroscopy and Surface-Enhanced Raman Scattering to Identify Colorants in Art: An Experiment for an Upper-Division Chemistry Laboratory

    Science.gov (United States)

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

    2015-01-01

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

  17. Profile disparity of Raman-scattered O VI in symbiotic stars

    International Nuclear Information System (INIS)

    Lee, Hee-Won

    2016-01-01

    Symbiotic stars are wide binary systems consisting of a hot compact star (usually a white dwarf) and a mass losing giant. Symbiotic activities are believed to occur through gravitational capture of a fraction of the slow stellar wind from the giant. Raman scattered features of O VI resonance doublet 1032 and 1038 appearing at around 6825 Å and 7082 Å are a unique spectroscopic diagnostic tool to probe the mass transfer process in symbiotic stars. The Raman O VI features often exhibit multiple peak structures and in many cases the blue peak of 7082 features is relatively more suppressed than that of 6825 features. We propose that the disparity of the two profiles is attributed to the local variation of optical depths of O VI, implying that the accretion flow is convergent in the red emission region and divergent in the blue emission region. It is argued in this presentation that Raman scattering by atomic hydrogen is a natural mirror to provide an edge-on view of the accretion disk and a lateral view of the bipolar outflow in symbiotic stars. We discuss the spectropolarimetric implications of this interpretation. (paper)

  18. FT-IR, FT-Raman spectra and DFT calculations of melaminium perchlorate monohydrate

    Science.gov (United States)

    Kanagathara, N.; Marchewka, M. K.; Drozd, M.; Renganathan, N. G.; Gunasekaran, S.; Anbalagan, G.

    2013-08-01

    Melaminium perchlorate monohydrate (MPM), an organic material has been synthesized by slow solvent evaporation method at room temperature. Powder X-ray diffraction analysis confirms that MPM crystal belongs to triclinic system with space group P-1. FTIR and FT Raman spectra are recorded at room temperature. Functional group assignment has been made for the melaminium cations and perchlorate anions. Vibrational spectra have also been discussed on the basis of quantum chemical density functional theory (DFT) calculations using Firefly (PC GAMESS) version 7.1 G. Vibrational frequencies are calculated and scaled values are compared with experimental values. The assignment of the bands has been made on the basis of the calculated PED. The Mulliken charges, HOMO-LUMO orbital energies are analyzed directly from Firefly program log files and graphically illustrated. HOMO-LUMO energy gap and other related molecular properties are also calculated. The theoretically constructed FT-IR and FT-Raman spectra of MPM coincide with the experimental one. The chemical structure of the compound has been established by 1H and 13C NMR spectra. No detectable signal was observed during powder test for second harmonic generation.

  19. Resonance Raman and surface-enhanced resonance Raman spectra of LH2 antenna complex from Rhodobacter sphaeroides and Ectothiorhodospira sp. excited in the Qx and Qy transitions.

    Science.gov (United States)

    Chumanov, G; Picorel, R; Ortiz de Zarate, I; Cotton, T M; Seibert, M

    2000-05-01

    Well-resolved vibrational spectra of LH2 complex isolated from two photosynthetic bacteria, Rhodobacter sphaeroides and Ectothiorhodospira sp., were obtained using surface-enhanced resonance Raman scattering (SERRS) exciting into the Qx and the Qy transitions of bacteriochlorophyll a. High-quality SERRS spectra in the Qy region were accessible because the strong fluorescence background was quenched near the roughened Ag surface. A comparison of the spectra obtained with 590 nm and 752 nm excitation in the mid- and low-frequency regions revealed spectral differences between the two LH2 complexes as well as between the LH2 complexes and isolated bacteriochlorophyll a. Because peripheral modes of pigments contribute mainly to the low-frequency spectral region, frequencies and intensities of many vibrational bands in this region are affected by interactions with the protein. The results demonstrate that the microenvironment surrounding the pigments within the two LH2 complexes is somewhat different, despite the fact that the complexes exhibit similar electronic absorption spectra. These differences are most probably due to specific pigment-pigment and pigment-protein interactions within the LH2 complexes, and the approach might be useful for addressing subtle static and dynamic structural variances between pigment-protein complexes from different sources or in complexes altered chemically or genetically.

  20. Plasmon enhancement of Raman scattering and fluorescence for rhodamine 6G molecules in the porous glass and PVA films with nanoparticles of silver citrate hydrosol

    International Nuclear Information System (INIS)

    Konstantinova, E I; Zyubin, A U; Samusev, I G; Slezhkin, V A; Bryukhanov, V V

    2016-01-01

    The study of Raman and fluorescence spectra for Rhodamine 6G molecules in a film of polyvinyl alcohol on the modified by silver nanoparticles (NPs) porous glass and without the porous glass has been done. The gain of the scattering intensity and fluorescence emission has been obtained in the presence of silver nanoparticles. The gain order was obtained as ∼ 10"1"1 (paper)

  1. Study of high-temperature multiplex HCl coherent anti-Stokes Raman spectroscopy spectra.

    Science.gov (United States)

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

    1993-02-20

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

  2. The Utilization of Low Frequency Raman Spectra of Gases for the Study of Molecules with Large Amplitude Vibration

    Institute of Scientific and Technical Information of China (English)

    James R. Durig; Sarah Xiao-hua Zhou; Joshua Klaassen; Arindam Ganguly

    2009-01-01

    The utilization of the Raman spectra of the low frequency bending mode for three quasi-linear molecules, disiloxane, (SiH3)2 O; methylisocyanate, CH3NCO; and dimethy lisocyanate, (CH3)2SiHNCO for observing the low frequency anharmonic bending vibration is demonstrated which is superior to the corresponding far infrared spectra. From the observed frequencies from the Raman spectra the potential function governing the heavy atom motion to linearity has been obtained from which the barrier has been determined. These experimental values are compared to the ab ini-tio predicted values. Also low frequency Raman spectra of the ring puckering vibration of chlorocy-clobutane, c-C4H7Cl, bromocyclobutane, c-C4H7Br, and aminocyclobutane, c-C4H7NH2, have been utilized to obtain the potential function governing the ring inversion for these molecules. The deter-mined barriers to planarity are compared to those obtained from MP2 (full) ab initio and density functional theory B3LYP calculations by utilizing a variety of basis sets. For all of these studies it is shown that the Raman spectra are superior to the infrared spectra for determining the frequencies of the excited state transitions.

  3. Graphene Dendrimer-stabilized silver nanoparticles for detection of methimazole using Surface-enhanced Raman scattering with computational assignment

    Science.gov (United States)

    Saleh, Tawfik A.; Al-Shalalfeh, Mutasem M.; Al-Saadi, Abdulaziz A.

    2016-08-01

    Graphene functionalized with polyamidoamine dendrimer, decorated with silver nanoparticles (G-D-Ag), was synthesized and evaluated as a substrate with surface-enhanced Raman scattering (SERS) for methimazole (MTZ) detection. Sodium borohydride was used as a reducing agent to cultivate silver nanoparticles on the dendrimer. The obtained G-D-Ag was characterized by using UV-vis spectroscopy, scanning electron microscope (SEM), high-resolution transmission electron microscope (TEM), Fourier-transformed infrared (FT-IR) and Raman spectroscopy. The SEM image indicated the successful formation of the G-D-Ag. The behavior of MTZ on the G-D-Ag as a reliable and robust substrate was investigated by SERS, which indicated mostly a chemical interaction between G-D-Ag and MTZ. The bands of the MTZ normal spectra at 1538, 1463, 1342, 1278, 1156, 1092, 1016, 600, 525 and 410 cm-1 were enhanced due to the SERS effect. Correlations between the logarithmical scale of MTZ concentrations and SERS signal intensities were established, and a low detection limit of 1.43 × 10-12 M was successfully obtained. The density functional theory (DFT) approach was utilized to provide reliable assignment of the key Raman bands.

  4. Three-beam double stimulated Raman scatterings: Cascading configuration

    Science.gov (United States)

    Rao, B. Jayachander; Cho, Minhaeng

    2018-03-01

    Two-beam stimulated Raman scattering (SRS) has been used in diverse label-free spectroscopy and imaging applications of live cells, biological tissues, and functional materials. Recently, we developed a theoretical framework for the three-beam double SRS processes that involve pump, Stokes, and depletion beams, where the pump-Stokes and pump-depletion SRS processes compete with each other. It was shown that the net Stokes gain signal can be suppressed by increasing the depletion beam intensity. The theoretical prediction has been experimentally confirmed recently. In the previous scheme for a selective suppression of one SRS by making it compete with another SRS, the two SRS processes occur in a parallel manner. However, there is another possibility of three-beam double SRS scheme that can be of use to suppress either Raman gain of the Stokes beam or Raman loss of the pump beam by depleting the Stokes photons with yet another SRS process induced by the pair of Stokes and another (second) Stokes beam. This three-beam double SRS process resembles a cascading energy transfer process from the pump beam to the first Stokes beam (SRS-1) and subsequently from the first Stokes beam to the second Stokes beam (SRS-2). Here, the two stimulated Raman gain-loss processes are associated with two different Raman-active vibrational modes of solute molecule. In the present theory, both the radiation and the molecules are treated quantum mechanically. We then show that the cascading-type three-beam double SRS can be described by coupled differential equations for the photon numbers of the pump and Stokes beams. From the approximate solutions as well as exact numerical calculation results for the coupled differential equations, a possibility of efficiently suppressing the stimulated Raman loss of the pump beam by increasing the second Stokes beam intensity is shown and discussed. To further prove a potential use of this scheme for developing a super-resolution SRS microscopy, we

  5. Enhanced Raman scattering assisted by ultrahigh order modes of the double metal cladding waveguide

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Tian; Huang, Liming; Jin, Yonglong; Fang, Jinghuai, E-mail: cyin.phys@gmail.com, E-mail: fjhuai@ntu.edu.cn [Physics Department, Nantong University, No. 9, Seyuan Road, Nantong, Jiangsu 226007 (China); Yin, Cheng, E-mail: cyin.phys@gmail.com, E-mail: fjhuai@ntu.edu.cn [Jiangsu Key Laboratory of Power Transmission and Distribution Equipment Technology, Hohai University, Changzhou 213022 (China); Huang, Meizhen [Department of Instrument Science and Engineering, Shanghai Jiaotong University, No. 800, DongChuan Road, Shanghai 200240 (China)

    2014-10-20

    Distinguished from the usual strategy to enhance the Raman scattering such as creating hot spots in the surface-enhanced Raman scattering, this paper takes a quite different approach based on the double metal cladding waveguide. The target analyte is located in the guiding layer of sub-millimeter scale, where several ultrahigh order modes with high intensity are simultaneously excited via a focused laser beam. The experimental setup is simple, and both simulation and experimental results confirm the enhancement mechanism of these oscillating modes. Other appealing features include the large detection area and the ability to excite guided modes via both polarizations. This scheme can be applied to large molecules detection and readily integrated with other Raman enhancement techniques.

  6. Two-magnon Raman scattering in quadratic double-layer antiferromagnets

    NARCIS (Netherlands)

    Pol, A. van der; Thurlings, M.P.H.; Wijn, H.W. de

    1980-01-01

    Two-magnon Raman spectra of ordered K3Mn2F7 are interpreted in terms of a two-dimensional four-sublattice spin-wave theory. In solving the equation of motion of the Green functions it is essential to include terms of the spin-wave Hamiltonian coupling the two magnon branches.

  7. Atomic substitution in selected high-temperature superconductors: Elucidating the nature of Raman spectra excitations

    Science.gov (United States)

    Hewitt, Kevin Cecil

    2000-10-01

    In this thesis, the effects of atomic substitution on the vibrational and electronic excitations found in the Raman spectra of selected high-temperature superconductors (HTS) are studied. In particular, atomic and isotopic substitution methods have been used to determine the character of features observed in the Raman spectra of Bi2Sr2Ca n-1CunO2 n+4+delta (n = 1 - Bi2201, n = 2 - Bi2212) and YBa2Cu3O7-delta (Y123). In Bi2201, Pb substitution for Bi (and Sr) has led to the reduction and eventual removal of the structural modulation, characteristic of all members of the Bi-family of HTS. The high quality single crystals and our sensitive triple spectrometer enabled identification of a pair of low frequency modes. The modes are determined to arise from shear and compressional rigid-layer vibrations. The normal state of underdoped cuprates is characterized by a pseudogap of unknown origin. In crystals of underdoped Bi2212 a spectral peak found at 590 cm-1, previously attributed to the pairing of quasiparticles (above Tc) and hence to the formation of a normal state pseudogap, has been found to soften by 3.8% with oxygen isotope exchange. In addition, the feature is absent in fully oxygenated and yttrium underdoped crystals. In this study, the first of its kind on underdoped and isotope substituted Bi2212, the feature has been assigned to stretching vibrations of oxygen in the a-b plane. Bi2212 crystals with varying hole concentrations (0.07 Raman scattering experiments that sample the diagonal (B 2g) and principal axes (B1 g) of the BZ have led us to conclude that the superconducting gap possesses dx2-y2 symmetry, in the underdoped and overdoped regimes. It is found that the magnitude of the superconducting gap (Delta(k)) is sensitive to changes in p. Studies of the pair-breaking peak found in the B1g spectra allow us to conclude that the magnitude of the maximum gap (Deltamax) decreases monotonically with increasing hole doping, for p > 0.13. The pair

  8. 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.

  9. Formation of gold nanorods and gold nanorod films for surface-enhanced Raman scattering spectroscopy

    International Nuclear Information System (INIS)

    Trotsyuk, L.L.; Kulakovich, O.S.; Shabunya-Klyachkovskaya, E.V.; Gaponenko, S.V.; Vashchenko, S.V.

    2016-01-01

    The formation of gold nanorods as well as thin films prepared via electrostatic deposition of gold nanorods has been investigated. The obtained gold nanorods films have been used as substrates for the surface-enhanced Raman scattering analysis of sulfur-free organic molecules mitoxantrone and malachite green as well as inorganic malachite microcrystals for the first time. The additional modification of films with L-cysteine allows one to significantly extend the use of gold nanorods for the surface-enhanced Raman scattering analysis. (authors)

  10. Coherent Raman Scattering Microscopy in Biology and Medicine

    Science.gov (United States)

    Zhang, Chi; Zhang, Delong; Cheng, Ji-Xin

    2016-01-01

    Advancements in coherent Raman scattering (CRS) microscopy have enabled label-free visualization and analysis of functional, endogenous biomolecules in living systems. When compared with spontaneous Raman microscopy, a key advantage of CRS microscopy is the dramatic improvement in imaging speed, which gives rise to real-time vibrational imaging of live biological samples. Using molecular vibrational signatures, recently developed hyperspectral CRS microscopy has improved the readout of chemical information available from CRS images. In this article, we review recent achievements in CRS microscopy, focusing on the theory of the CRS signal-to-noise ratio, imaging speed, technical developments, and applications of CRS imaging in bioscience and clinical settings. In addition, we present possible future directions that the use of this technology may take. PMID:26514285

  11. In situ, accurate, surface-enhanced Raman scattering detection of cancer cell nucleus with synchronous location by an alkyne-labeled biomolecular probe.

    Science.gov (United States)

    Zhang, Jing; Liang, Lijia; Guan, Xin; Deng, Rong; Qu, Huixin; Huang, Dianshuai; Xu, Shuping; Liang, Chongyang; Xu, Weiqing

    2018-01-01

    A surface-enhanced Raman scattering (SERS) method for in situ detection and analysis of the intranuclear biomolecular information of a cell has been developed based on a small, biocompatible, nuclear-targeting alkyne-tagged deoxyribonucleic acid (DNA) probe (5-ethynyl-2'-deoxyuridine, EDU) that can specially accumulate in the cell nucleus during DNA replications to precisely locate the nuclear region without disturbance in cell biological activities and functions. Since the specific alkyne group shows a Raman peak in the Raman-silent region of cells, it is an interior label to visualize the nuclear location synchronously in real time when measuring the SERS spectra of a cell. Because no fluorescent-labeled dyes were used for locating cell nuclei, this method is simple, nondestructive, non- photobleaching, and valuable for the in situ exploration of vital physiological processes with DNA participation in cell organelles. Graphical abstract A universal strategy was developed to accurately locate the nuclear region and obtain precise molecular information of cell nuclei by SERS.

  12. Comparison of the Raman spectra of ion irradiated soot and collected extraterrestrial carbon

    Science.gov (United States)

    Brunetto, R.; Pino, T.; Dartois, E.; Cao, A.-T.; d'Hendecourt, L.; Strazzulla, G.; Bréchignac, Ph.

    2009-03-01

    We use a low pressure flame to produce soot by-products as possible analogues of the carbonaceous dust present in diverse astrophysical environments, such as circumstellar shells, diffuse interstellar medium, planetary disks, as well as in our own Solar System. Several soot samples, displaying an initial chemical diversity from aromatic to aliphatic dominated material, are irradiated with 200-400 keV H +, He +, and Ar ++ ions, with fluences comprised between 10 14 and 10 16 ions/cm 2, to simulate expected radiation induced modification on extraterrestrial carbon. The evolution of the samples is monitored using Raman spectroscopy, before, during, and after irradiation. A detailed analysis of the first- and second-order Raman spectra is performed, using a fitting combination of Lorentzian and/or Gaussian-shaped bands. Upon irradiation, the samples evolve toward an amorphous carbon phase. The results suggest that the observed variations are more related to vacancy formation than ionization processes. A comparison with Raman spectra of extraterrestrial organic matter and other irradiation experiments of astrophysically relevant carbonaceous materials is presented. The results are consistent with previous experiments showing mostly amorphization of various carbonaceous materials. Irradiated soots have Raman spectra similar to those of some meteorites, IDPs, and Comet Wild 2 grains collected by the Stardust mission. Since the early-Sun expected irradiation fluxes sufficient for amorphization are compatible with accretion timescales, our results support the idea that insoluble organic matter (IOM) observed in primitive meteorites has experienced irradiation-induced amorphization prior to the accretion of the parent bodies, emphasizing the important role played by early solar nebula processing.

  13. Resonant A1 phonon and four-magnon Raman scattering in hexagonal HoMnO3 thin film

    International Nuclear Information System (INIS)

    Chen Xiangbai; Thi Minh Hien, Nguyen; Yang, In-Sang; Lee, D; Jang, S-Y; Noh, T W

    2010-01-01

    We present the results of resonant Raman scattering of the A 1 phonon at 680 cm -1 and of the four-magnon at 760 cm -1 in hexagonal HoMnO 3 thin film. We find that the A 1 phonon at 680 cm -1 shows a strong resonance effect near the on-site Mn d-d transition at ∼1.7 eV. Our Raman results show that the four-magnon scattering can be selectively excited with red lasers of 647 nm (1.92 eV) and 671 nm (1.85 eV), but are not detectable with green lasers of 532 nm (2.33 eV), indicating that the four-magnon scattering in hexagonal HoMnO 3 has an extremely strong resonance effect also near the on-site Mn d-d transition at ∼1.7 eV. Furthermore, through the analyses of our study of the resonant four-magnon Raman scattering and earlier studies of the resonant two-magnon Raman scattering, we propose a simple general model for all resonant magnon scattering. Our simple general model predicts a simple method for the investigation of the spin-flipping/spin-wave in magnetic materials, which would have significant impacts on the applications of spintronic devices.

  14. An Investigation on Micro-Raman Spectra and Wavelet Data Analysis for Pemphigus Vulgaris Follow-up Monitoring

    OpenAIRE

    Camerlingo, Carlo; Zenone, Flora; Perna, Giuseppe; Capozzi, Vito; Cirillo, Nicola; Gaeta, Giovanni Maria; Lepore, Maria

    2008-01-01

    A wavelet multi-component decomposition algorithm has been used for data analysis of micro-Raman spectra of blood serum samples from patients affected by pemphigus vulgaris at different stages. Pemphigus is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially fatal outcome. Spectra were measured by means of a Raman confocal microspectrometer apparatus using the 632.8 nm line of a He-Ne laser source. A discrete wavelet transform decomposition method has...

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

    DEFF Research Database (Denmark)

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

    2017-01-01

    Raman spectroscopy is a well-known analytical technique for identifying and analyzing chemical species. Since Raman scattering is a weak effect, surface-enhanced Raman spectroscopy (SERS) is often employed to amplify the signal. SERS signal surface mapping is a common method for detecting trace...... to directly and reliably identify the Raman modes, with overall performance similar to the state of the art non-negative matrix factorization approach. However, the model provides better interpretation and is a step towards enabling the use of SERS in detection of trace amounts of molecules in real-life...

  16. A Raman scattering and FT-IR spectroscopic study on the effect of the solar radiation in Antarctica on bovine cornea

    Science.gov (United States)

    Yamamoto, Tatsuyuki; Murakami, Naoki; Yoshikiyo, Keisuke; Takahashi, Tetsuya; Yamamoto, Naoyuki

    2010-01-01

    The Raman scattering and FT-IR spectra of the corneas, transported to the Syowa station in Antarctica and exposed to the solar radiation of the mid-summer for four weeks, were studied to reveal that type IV collagen involved in corneas were fragmented. The amide I and III Raman bands were observed at 1660 and 1245 cm -1, respectively, and the amide I and II infrared bands were observed at 1655 and 1545 cm -1, respectively, for original corneas before exposure. The background of Raman signals prominently increased and the ratio of amide II infrared band versus amide I decreased by the solar radiation in Antarctica. The control experiment using an artificial UV lamp was also performed in laboratory. The decline rate of the amide II/amide I was utilized for estimating the degree of fragmentation of collagen, to reveal that the addition of vitamin C suppressed the reaction while the addition of sugars promoted it. The effect of the solar radiation in Antarctica on the corneas was estimated as the same as the artificial UV lamp of four weeks (Raman) or one week (FT-IR) exposure.

  17. Raman scattering enhancement in photon-plasmon resonance mediated metal-dielectric microcavity

    International Nuclear Information System (INIS)

    Guddala, Sriram; Narayana Rao, D.; Dwivedi, Vindesh K.; Vijaya Prakash, G.

    2013-01-01

    Here, we report the photon-plasmon interaction scheme and enhanced field strengths resulted into the amplification of phonon in a novel microcavity. A metal-dielectric microcavity, with unified cavity photonic mode and localized surface plasmon resonances, is visualized by impregnating the gold nanoparticles into the deep see-through nano-sized pores of porous silicon microcavity. The intense optical field strengths resulting from the photon-plasmon interactions are probed by both resonant and non-resonant Raman scattering experiments. Due to photon-plasmon-phonon interaction mechanism, several orders of enhancement in the intensity of scattered Raman Stokes photon (at 500 cm −1 ) are observed. Our metal nanoparticle-microcavity hybrid system shows the potential to improve the sensing figure of merit as well as the applications of plasmonics for optoelectronics, photovoltaics, and related technologies

  18. Frontiers of surface-enhanced Raman scattering single nanoparticles and single cells

    CERN Document Server

    Ozaki, Yukihiro; Aroca, Ricardo

    2014-01-01

    A comprehensive presentation of Surface-Enhanced Raman Scattering (SERS) theory, substrate fabrication, applications of SERS to biosystems, chemical analysis, sensing and fundamental innovation through experimentation. Written by internationally recognized editors and contributors. Relevant to all those within the scientific community dealing with Raman Spectroscopy, i.e. physicists, chemists, biologists, material scientists, physicians and biomedical scientists. SERS applications are widely expanding and the technology is now used in the field of nanotechnologies, applications to biosystems, nonosensors, nanoimaging and nanoscience.

  19. Photon distribution function for stocks wave for stimulated Raman scattering

    International Nuclear Information System (INIS)

    Man'ko, O.V.; Tcherniega, N.V.

    1997-04-01

    New time-dependent integrals of motion are found for stimulated Raman scattering. Explicit formula for the photon-number probability distribution as a function of the laser-field intensity and the medium parameters is obtained in terms of Hermite polynomials of two variables. (author). 29 refs

  20. Looking behind the scenes: Raman spectroscopy of top-gated epitaxial graphene through the substrate

    International Nuclear Information System (INIS)

    Fromm, F; Wehrfritz, P; Seyller, Th; Hundhausen, M

    2013-01-01

    Raman spectroscopy is frequently used to study the properties of epitaxial graphene grown on silicon carbide (SiC). In this work, we present a confocal micro-Raman study of epitaxial graphene on SiC(0001) in top-down geometry, i.e. in a geometry where both the primary laser light beam as well as the back-scattered light is guided through the SiC substrate. Compared to the conventional top-up configuration, in which confocal micro-Raman spectra are measured from the air side, we observe a significant intensity enhancement in top-down configuration, indicating that most of the Raman-scattered light is emitted into the SiC substrate. The intensity enhancement is explained in terms of dipole radiation at a dielectric surface. The new technique opens the possibility to probe graphene layers in devices where the graphene layer is covered by non-transparent materials. We demonstrate this by measuring gate-modulated Raman spectra of a top-gated epitaxial graphene field effect device. Moreover, we show that these measurements enable us to disentangle the effects of strain and charge on the positions of the prominent Raman lines in epitaxial graphene on SiC. (paper)

  1. Composition and Structure of Microalgae Indicated in Raman and Hyperspectral Spectra and Scanning Electron Microscopy: from Cyanobacteria to Isolates from Coal-bed Methane Water Ponds

    Science.gov (United States)

    Zhou, X.; Zhou, Z.; Apple, M. E.; Spangler, L.

    2017-12-01

    the main absorption bands and scattering bands were located and their association with composition and structure were analyzed and discussed. SEM micrographs will be collected and the composition and structure derived from the SEM micrographs will be discussed and compared with those derived from the Raman spectra and hyperspectral spectra.

  2. [Fluorescent and Raman scattering by molecules embedded in small particles]: Annual report, 1983

    International Nuclear Information System (INIS)

    Chew, H.; McNulty, P.J.

    1983-01-01

    An overview is given of the model formulated for fluorescent and Raman scattering by molecules embedded in or in the vicinity of small particles. The model takes into account the size, shape, refractive index, and morphology of the host particles. Analytic and numerical results have been obtained for spherical (one and more layers, including magnetic dipole transitions), cylindrical, and spheroidal particles. Particular attention has been given to the spherical case with fluorescent/Raman scatterers uniformly distributed in the particles radiating both coherently and incoherently. Depolarization effects have been studied with suitable averaging process, and good agreement with experiment has been obtained. Analytic and numerical results have been obtained for the elastic scattering of evanescent waves; these results are useful for the study of fluorescence under excitation by evanescent waves

  3. Quick detection of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces by surface-enhanced Raman spectroscopy

    International Nuclear Information System (INIS)

    Huang, Hao; Shi, Hong; Chen, Weiwei; Yu, Yun; Lin, Duo; Xu, Qian; Feng, Shangyuan; Lin, Juqiang; Chen, Rong

    2013-01-01

    A surface-enhanced Raman spectroscopy (SERS) method was developed for the analysis of traditional Chinese medicine ‘Atractylodis Macrocephalae Rhizoma’ pieces (AMRP) for the first time with the aim to develop a quick method for traditional Chinese medicine detection. Both Raman spectra and SERS spectra were obtained from AMRP, and tentative assignments of the Raman bands in the measured spectra suggested that only a few weak Raman peaks could be observed in the regular Raman spectra, while primary Raman peaks at around 536, 555, 619, 648, 691, 733, 790, 958, 1004, 1031, 1112, 1244, 1324, 1395, 1469, 1574 and 1632 cm −1 could be observed in the SERS spectra, with the strongest signals at 619, 733, 958, 1324, 1395 and 1469 cm −1 . This was due to a strong interaction between the silver colloids and the AMRP, which led to an extraordinary enhancement in the intensity of the Raman scattering in AMRP. This exploratory study suggests the SERS technique has great potential for providing a novel non-destructive method for effectively and accurately detecting traditional Chinese medicine without complicated separation and extraction. (paper)

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

    Directory of Open Access Journals (Sweden)

    Annepu Venkata Naga Vamsi

    2016-01-01

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

  5. The disorder-induced Raman scattering in Au/MoS{sub 2} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Gołasa, K., E-mail: Katarzyna.Golasa@fuw.edu.pl; Grzeszczyk, M.; Binder, J.; Bożek, R.; Wysmołek, A.; Babiński, A. [Faculty of Physics, University of Warsaw, ul. Pasteura 5, 02-093 Warszawa (Poland)

    2015-07-15

    The Raman scattering has been studied in heterostructures composed of a thin MoS{sub 2} flake and a 1-1.5 nm layer of thermally evaporated gold (Au). There have been Au nanoislands detected in the heterostructure. It has been found that their surface density and the average size depend on the MoS{sub 2} thickness. The Raman scattering spectrum in the heterostructure with a few monolayer MoS{sub 2} only weakly depends on the excitation (resonant vs. non-resonant) mode. The overall Raman spectrum corresponds to the total density of phonon states, which is characteristic for disordered systems. The disorder in the MoS{sub 2} layer is related to the mechanical strain induced in the MoS{sub 2} layer by the Au nanoislands. The strain results in the localization of phonon modes, which leads to the relaxation of the momentum conservation rule in the scattering process. The relaxation allows phonons from the whole MoS{sub 2} Brillouin zone to interact with electronic excitations. Our results show that the Au nanoislands resulted from thermal evaporation of a thin metal layer introduce substantial disorder into the crystalline structure of the thin MoS{sub 2} layers.

  6. Investigation of resonant Raman scattering in type II GaAs/AlAs superlattices

    International Nuclear Information System (INIS)

    Choi, H.

    2001-01-01

    As a consequence of the band alignment in GaAs/AIAs superlattices (SLs) and the indirect nature of bulk AIAs, quantum confinement can be used to engineer a Type II system. This produces an electron population in the AIAs longitudinal (X z ) or transverse (X xy ) zone-edge states, which is separated in both direct and reciprocal space from the hole population in the GaAs zone-centre (Γ) states. This thesis is an investigation of the electronic and vibrational structure of Type II GaAs/AIAs SLs using theoretical models and spectroscopic techniques, with special emphasis on Type II resonant Raman (RR) scattering. The majority of this thesis concerns short-period GaAs/AIAs SLs with X z as the lowest conduction band state. A model of the SL electronic band structure is presented, including the effects of interband Γ-X z mixing and the X-point camel's back structure. Interband mixing makes Γ-X z radiative transitions observable in photoluminescence (PL) and RR experiments. Phonon-assisted transitions from the X z state are also observed in PL experiments. Several of the participating phonon modes are unambiguously identified, in good agreement with recent reports. This thesis presents the first detailed experimental and theoretical study of Type II RR scattering from the incoming channel of the X z -related Type II bandgap. The X z - related Type II incoming RR spectra in the GaAs optic phonon region are compared with the Γ-related Type I outgoing RR spectra within several theoretical models. Thereby, the mechanisms of the Type II RR scattering, the origins of the RR lineshape and the polarisation dependence, are fully explained, clarifying the spectral features observed in the GaAs zone-centre optic phonon region. The Type II resonance also allows the observation of zone boundary (X-point) phonons from intervalley (IV) scattering. A model of the IV electron-phonon interaction involving X conduction band electrons and zone boundary phonons in Type II SLs is presented

  7. The effects of machine parameters on residual stress determined using micro-Raman spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

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

    1988-12-01

    The effects of machine parameters on residual stresses in single point diamond turned silicon and germanium have been investigated using micro-Raman spectroscopy. Residual stresses were sampled across ductile feed cuts in < 100 > silicon and germanium which were single point diamond turned using a variety of feed rates, rake angles and clearance angles. High spatial resolution micro-Raman spectra (1{mu}m spot) were obtained in regions of ductile cutting where no visible surface damage was present. The use of both 514-5nm and 488.0nm excitation wavelengths, by virtue of their differing characteristic penetration depths in the materials, allowed determinations of stress profiles as a function of depth into the sample. Previous discussions have demonstrated that such Raman spectra will exhibit asymmetrically broadened peaks which are characteristic of the superposition of a continuum of Raman scatterers from the various depths probed. Depth profiles of residual stress were obtained using computer deconvolution of the resulting asymmetrically broadened raman spectra.

  8. Improved Savitzky-Golay-method-based fluorescence subtraction algorithm for rapid recovery of Raman spectra.

    Science.gov (United States)

    Chen, Kun; Zhang, Hongyuan; Wei, Haoyun; Li, Yan

    2014-08-20

    In this paper, we propose an improved subtraction algorithm for rapid recovery of Raman spectra that can substantially reduce the computation time. This algorithm is based on an improved Savitzky-Golay (SG) iterative smoothing method, which involves two key novel approaches: (a) the use of the Gauss-Seidel method and (b) the introduction of a relaxation factor into the iterative procedure. By applying a novel successive relaxation (SG-SR) iterative method to the relaxation factor, additional improvement in the convergence speed over the standard Savitzky-Golay procedure is realized. The proposed improved algorithm (the RIA-SG-SR algorithm), which uses SG-SR-based iteration instead of Savitzky-Golay iteration, has been optimized and validated with a mathematically simulated Raman spectrum, as well as experimentally measured Raman spectra from non-biological and biological samples. The method results in a significant reduction in computing cost while yielding consistent rejection of fluorescence and noise for spectra with low signal-to-fluorescence ratios and varied baselines. In the simulation, RIA-SG-SR achieved 1 order of magnitude improvement in iteration number and 2 orders of magnitude improvement in computation time compared with the range-independent background-subtraction algorithm (RIA). Furthermore the computation time of the experimentally measured raw Raman spectrum processing from skin tissue decreased from 6.72 to 0.094 s. In general, the processing of the SG-SR method can be conducted within dozens of milliseconds, which can provide a real-time procedure in practical situations.

  9. Surface-enhanced Raman scattering based nonfluorescent probe for multiplex DNA detection.

    Science.gov (United States)

    Sun, Lan; Yu, Chenxu; Irudayaraj, Joseph

    2007-06-01

    To provide rapid and accurate detection of DNA markers in a straightforward, inexpensive, and multiplex format, an alternative surface-enhanced Raman scattering based probe was designed and fabricated to covalently attach both DNA probing sequence and nonfluorescent Raman tags to the surface of gold nanoparticles (DNA-AuP-RTag). The intensity of Raman signal of the probes could be controlled through the surface coverage of the nonfluorescent Raman tags (RTags). Detection sensitivity of these probes could be optimized by fine-tuning the amount of DNA molecules and RTags on the probes. Long-term stability of the DNA-AuP-RTag probes was found to be good (over 3 months). Excellent multiplexing capability of the DNA-AuP-RTag scheme was demonstrated by simultaneous identification of up to eight probes in a mixture. Detection of hybridization of single-stranded DNA to its complementary targets was successfully accomplished with a long-term goal to use nonfluorescent RTags in a Raman-based DNA microarray platform.

  10. Influence of stimulated Raman scattering on the conversion efficiency in four wave mixing

    International Nuclear Information System (INIS)

    Wunderlich, R.; Moore, M.A.; Garrett, W.R.; Payne, M.G.

    1988-01-01

    Secondary nonlinear optical effects following parametric four wave mixing in sodium vapor are investigated. The generated ultraviolet radiation induces stimulated Raman scattering and other four wave mixing process. Population transfer due to Raman transitions strongly influences the phase matching conditions for the primary mixing process. Pulse shortening and a reduction in conversion efficiency are observed. 8 refs., 3 figs

  11. Vibrational assignments for the Raman and the phosphorescence spectra of 9,10-anthraquinone and 9,10-anthraquinone-d81

    International Nuclear Information System (INIS)

    Lehmann, K.K.; Smolarek, J.; Khalil, O.S.; Goodman, L.

    1979-01-01

    The Raman spectra of 9,10-anthraquinone (AQ) and 9,10-anthraquinone-d/sub 8/ are examined. Raman band assignments are made from this data and from a published normal coordinate analysis. The Raman spectra of AQ at 5K is reported and vibrational assignments for the phosphorescence spectra of AQ in n-hexane at 4.2 K are reexamined in light of new 3 B 1 /sub g/ → 1 A/sub g/ phosphorescence data. Contrary to previous work from this laboratory, it is concluded that although higher order vibronic interactions may be operative between the two closely spaced 3 A/sub u/- 3 B 1 /sub g/ electronic states, these interactions are not manifested in the phosphorescence spectra of AQ in n-hexane at 4.2 K

  12. Raman scattering in air: four-dimensional analysis

    International Nuclear Information System (INIS)

    Lin, Y.; Kessler, T.J.; Lawrence, G.N.

    1994-01-01

    Inertial confinement fusion requires propagation of high-intensity, pulse-shaped IR and UV laser beams through long air paths. Such beams are subject to energy losses and decreased beam quality as a result by stimulated rotational Raman scattering (SRRS). In this paper we describe how quantum fluctuations, stimulated Raman amplification, diffraction propagation, and optical aberrations interact during the propagation of short, high-power laser pulses using a four-dimensional (4-D) model of the optical beams and the medium. The 4-D model has been incorporated into a general optical-propagation computer program that allows the entire optical system to be modeled and that is implemented on high-end personal computers, workstations, and supercomputers. The numerical model is used to illustrate important phenomena in the evolution of the optical beams. In addition, the OMEGA Upgrade laser system is used as a design case to illustrate the various considerations for inertial confinement fusion laser design

  13. Elastic and Raman scattering of photons from the giant dipole resonance

    International Nuclear Information System (INIS)

    Bar-Noy, T.

    1978-12-01

    In the present work we investigated nuclear Raman and elastic scattering of photons from the Giant Dipole Resonance (GDR) of medium and heavy nuclei. The photons beams were obtained from thermal neutron capture on V, Fe, Ni, Cu and Cr discs, utilizing the IRR-2 reactor. Nine targets, 159 Tb, 165 Ho, 175 Lu, 181 Ta, 197 Au, 209 Bi, 232 Th, 237 Np, and 238 U, representing all spherical and deformed nuclei in the region of medium and heavy nuclei, were used. As preliminary works, we discovered and investigated the 11.4 MeV γ-line, measured the attenuation coefficients at 9 and 11.4 MeV, performed a numerical calculation of Delbrueck amplitudes and modified the Simple Rotator Model (SRM). The absolute scattering cross-sections were measured for each scatterer at 4-8 different energies, and angular distributions in the range 90 deg to 140 deg were carried out at 9 MeV and 11.4 MeV. The experimental results were compared with theoretical predictions of the modified SRM and the Dynamic Collective Model (DCM). The results proved that the modified SRM describes appropriately the scattering from the GDR, including elastic and Raman absolute cross-sections and their angular distributions. (author)

  14. 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...

  15. Diameter Effect of Silver Nanorod Arrays to Surface-enhanced Raman Scattering

    International Nuclear Information System (INIS)

    Gu, Geun Hoi; Kim, Min Young; Yoon, Hyeok Jin; Suh, Jung Sang

    2014-01-01

    The effect the diameter of silver nanorod arrays whose distance between the nanorods was uniform at 65 nm have on Surface-enhanced Raman Scattering (SERS) has been studied by varying the diameter from 28 to 51 nm. Nanorod length was fixed at approximately 62 nm, which is the optimum length for SERS by excitation with a 632.8 nm laser line. The transverse and longitudinal modes of the surface plasmon of these silver nanorods were near 400 and 630 nm, respectively. The extinction of the longitudinal mode increased with increasing nanorod diameter, while the transverse mode did not change significantly. High-quality SERS spectra of p-aminothiophenol and benzenethiol adsorbed on the tips of the silver nanorods were observed by excitation with a 632.8 nm laser line. The SERS enhancement increased with increasing nanorod diameter. We concluded that the SERS enhancement increases when the diameter of silver nanorods is increased mainly by increasing the excitation efficiency of the longitudinal mode. The enhancement factor for the silver nanorods with a 51 nm diameter was approximately 2 Χ 10 7

  16. Electronic Raman scattering in Bi2Sr2CaCu2O8=δ

    International Nuclear Information System (INIS)

    Quilty, J.W.; Trodahl, H.J.; Pooke, D.

    1996-01-01

    Full text: High-T c superconductors exhibit a definite Electronic Raman Scattering (ERS) continuum, which most materials do not. Typically, the continuum is relatively flat in the normal state, while below T c the ERS spectrum shows reduced scattering at the lowest Raman shifts and a peak close to the superconducting gap energy. The behaviour below T c is due to the breaking of Cooper pairs and reflects the superconducting density of states, hence revealing the superconducting gap. Through an appropriate choice of incident and scattered polarisation vectors, the electronic Raman continuum of high-T c superconductors may also be used to reveal information on the symmetry of the superconducting gap. Previous studies of the electronic continuum show that a broad peak associated with the superconducting gap forms in the continuum below T c in these materials, when compared to the normal-state. We report temperature and polarisation dependent ERS measurements on differently-doped Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) single crystals, within a temperature range of 300 K to 10 K

  17. Nitric oxide concentration measurements in atmospheric pressure flames using electronic-resonance-enhanced coherent anti-Stokes Raman scattering

    Science.gov (United States)

    Chai, N.; Kulatilaka, W. D.; Naik, S. V.; Laurendeau, N. M.; Lucht, R. P.; Kuehner, J. P.; Roy, S.; Katta, V. R.; Gord, J. R.

    2007-06-01

    We report the application of electronic-resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) for measurements of nitric oxide concentration ([NO]) in three different atmospheric pressure flames. Visible pump (532 nm) and Stokes (591 nm) beams are used to probe the Q-branch of the Raman transition. A significant resonance enhancement is obtained by tuning an ultraviolet probe beam (236 nm) into resonance with specific rotational transitions in the (v’=0, v”=1) vibrational band of the A2Σ+-X2Π electronic system of NO. ERE-CARS spectra are recorded at various heights within a hydrogen-air flame producing relatively low concentrations of NO over a Hencken burner. Good agreement is obtained between NO ERE-CARS measurements and the results of flame computations using UNICORN, a two-dimensional flame code. Excellent agreement between measured and calculated NO spectra is also obtained when using a modified version of the Sandia CARSFT code for heavily sooting acetylene-air flames (φ=0.8 to φ=1.6) on the same Hencken burner. Finally, NO concentration profiles are measured using ERE-CARS in a laminar, counter-flow, non-premixed hydrogen-air flame. Spectral scans are recorded by probing the Q1 (9.5), Q1 (13.5) and Q1 (17.5) Raman transitions. The measured shape of the [NO] profile is in good agreement with that predicted using the OPPDIF code, even without correcting for collisional effects. These comparisons between [NO] measurements and predictions establish the utility of ERE-CARS for detection of NO in flames with large temperature and concentration gradients as well as in sooting environments.

  18. Temperature dependence of Raman scattering spectra of Basub(0.50)Srsub(0.50)Nbsub(2)Osub(6) crystal

    International Nuclear Information System (INIS)

    Gorelik, V.S.; Rustamov, Kh.Sh.; Kuz'minov, Yu.S.; Sushchinskij, M.M.

    1977-01-01

    The change of the Raman spectra in the crystal Basub(x)Srsub(1-x)Nbsub(2)Osub(6) (x=0.50) in the temperature range of 80-500 K has been studied. A conventional technique with the application of an argon laser (π=4880 A) and a diffraction spectrometer was used. It has been established that in the observed spectrum a number of low frequency lines are present caused by vibrations of the crystalline lattice. It is shown that the growth of dielectric permittivity near the ferroelectric transition correlates with the observed growth of the spectral intensity in the low frequency spectrum range at the approach to the Gurie temperature. It was found that for the considered crystal, both a ''single-mode'' and a ''two-mode'' behaviour of the phonon spectrum take place

  19. Origin of the frequency shift of Raman scattering in chalcogenide glasses

    DEFF Research Database (Denmark)

    Han, X.C.; Tao, H.Z.; Gong, L.J.

    2014-01-01

    of the shift is associated with the topological connectivity of global network and/or the local environment of structural units, (e.g., tetrahedral GeSe4). Here we show the compositional evolution of the main Raman scattering frequency in Ge(SxSe1−x)2 glasses, and then clarify its structural origin. We keep...... units such as GeS4 tetrahedra. The ab-initio calculations of normal Raman mode combined with group theory analysis provide insight into the structural evolution of chalcogenide glasses with varying composition....

  20. Adaptive handling of Rayleigh and Raman scatter of fluorescence data based on evaluation of the degree of spectral overlap

    Science.gov (United States)

    Hu, Yingtian; Liu, Chao; Wang, Xiaoping; Zhao, Dongdong

    2018-06-01

    At present the general scatter handling methods are unsatisfactory when scatter and fluorescence seriously overlap in excitation emission matrix. In this study, an adaptive method for scatter handling of fluorescence data is proposed. Firstly, the Raman scatter was corrected by subtracting the baseline of deionized water which was collected in each experiment to adapt to the intensity fluctuations. Then, the degrees of spectral overlap between Rayleigh scatter and fluorescence were classified into three categories based on the distance between the spectral peaks. The corresponding algorithms, including setting to zero, fitting on single or both sides, were implemented after the evaluation of the degree of overlap for individual emission spectra. The proposed method minimized the number of fitting and interpolation processes, which reduced complexity, saved time, avoided overfitting, and most importantly assured the authenticity of data. Furthermore, the effectiveness of this procedure on the subsequent PARAFAC analysis was assessed and compared to Delaunay interpolation by conducting experiments with four typical organic chemicals and real water samples. Using this method, we conducted long-term monitoring of tap water and river water near a dyeing and printing plant. This method can be used for improving adaptability and accuracy in the scatter handling of fluorescence data.

  1. Vibrational infrared and Raman spectra of polypeptides: Fragments-in-fragments within molecular tailoring approach

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, Nityananda; Gadre, Shridhar R., E-mail: gadre@iitk.ac.in [Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2016-03-21

    The present work reports the calculation of vibrational infrared (IR) and Raman spectra of large molecular systems employing molecular tailoring approach (MTA). Further, it extends the grafting procedure for the accurate evaluation of IR and Raman spectra of large molecular systems, employing a new methodology termed as Fragments-in-Fragments (FIF), within MTA. Unlike the previous MTA-based studies, the accurate estimation of the requisite molecular properties is achieved without performing any full calculations (FC). The basic idea of the grafting procedure is implemented by invoking the nearly basis-set-independent nature of the MTA-based error vis-à-vis the respective FCs. FIF has been tested out for the estimation of the above molecular properties for three isomers, viz., β-strand, 3{sub 10}- and α-helix of acetyl(alanine){sub n}NH{sub 2} (n = 10, 15) polypeptides, three conformers of doubly protonated gramicidin S decapeptide and trpzip2 protein (PDB id: 1LE1), respectively, employing BP86/TZVP, M06/6-311G**, and M05-2X/6-31G** levels of theory. For most of the cases, a maximum difference of 3 cm{sup −1} is achieved between the grafted-MTA frequencies and the corresponding FC values. Further, a comparison of the BP86/TZVP level IR and Raman spectra of α-helical (alanine){sub 20} and its N-deuterated derivative shows an excellent agreement with the existing experimental spectra. In view of the requirement of only MTA-based calculations and the ability of FIF to work at any level of theory, the current methodology provides a cost-effective solution for obtaining accurate spectra of large molecular systems.

  2. Surface-Enhanced Raman Scattering Using Silica Whispering-Gallery Mode Resonators

    Science.gov (United States)

    Anderson, Mark S.

    2013-01-01

    The motivation of this work was to have robust spectroscopic sensors for sensitive detection and chemical analysis of organic and molecular compounds. The solution is to use silica sphere optical resonators to provide surface-enhanced spectroscopic signal. Whispering-gallery mode (WGM) resonators made from silica microspheres were used for surface-enhanced Raman scattering (SERS) without coupling to a plasmonic mechanism. Large Raman signal enhancement is observed by exclusively using 5.08-micron silica spheres with 785-nm laser excitation. The advantage of this non-plasmonic approach is that the active substrate is chemically inert silica, thermally stable, and relatively simple to fabricate. The Raman signal enhancement is broadly applicable to a wide range of molecular functional groups including aliphatic hydrocarbons, siloxanes, and esters. Applications include trace organic analysis, particularly for in situ planetary instruments that require robust sensors with consistent response.

  3. Laser sheet dropsizing based on two-dimensional Raman and Mie scattering.

    Science.gov (United States)

    Malarski, Anna; Schürer, Benedikt; Schmitz, Ingo; Zigan, Lars; Flügel, Alexandre; Leipertz, Alfred

    2009-04-01

    The imaging and quantification of droplet sizes in sprays is a challenging task for optical scientists and engineers. Laser sheet dropsizing (LSDS) combines the two-dimensional information of two different optical processes, one that is proportional to the droplet volume and one that depends on the droplet surface, e.g., Mie scattering. Besides Mie scattering, here we use two-dimensional Raman scattering as the volume-dependent measurement technique. Two different calibration strategies are presented and discussed. Two-dimensional droplet size distributions in a spray have been validated in comparison with the results of point-resolved phase Doppler anemometry (PDA) measurements.

  4. Laser sheet dropsizing based on two-dimensional Raman and Mie scattering

    International Nuclear Information System (INIS)

    Malarski, Anna; Schuerer, Benedikt; Schmitz, Ingo; Zigan, Lars; Fluegel, Alexandre; Leipertz, Alfred

    2009-01-01

    The imaging and quantification of droplet sizes in sprays is a challenging task for optical scientists and engineers. Laser sheet dropsizing (LSDS) combines the two-dimensional information of two different optical processes, one that is proportional to the droplet volume and one that depends on the droplet surface, e.g., Mie scattering. Besides Mie scattering, here we use two-dimensional Raman scattering as the volume-dependent measurement technique. Two different calibration strategies are presented and discussed. Two-dimensional droplet size distributions in a spray have been validated in comparison with the results of point-resolved phase Doppler anemometry (PDA) measurements

  5. One phonon resonant Raman scattering in free-standing quantum wires

    International Nuclear Information System (INIS)

    Zhao, Xiang-Fu; Liu, Cui-Hong

    2007-01-01

    The scattering intensity (SI) of a free-standing cylindrical semiconductor quantum wire for an electron resonant Raman scattering (ERRS) process associated with bulk longitudinal optical (LO) phonon modes and surface optical (SO) phonon modes is calculated separately for T=0 K. The Frohlich interaction is considered to illustrate the theory for GaAs and CdS systems. Electron states are confined within a free-standing quantum wire (FSW). Single parabolic conduction and valence bands are assumed. The selection rules are studied. Numerical results and a discussion are also presented for various radii of the cylindrical

  6. Normal Raman and SERS spectroscopy of the vitamin E

    International Nuclear Information System (INIS)

    Cai Tiantian; Gu Huaimin; Yuan Xiaojuan; Liu Fangfang

    2011-01-01

    In this study, surface-enhanced Raman scattering(SERS)spectra of vitamin E were obtained on colloidal silver(Ag). Alpha-(-) tocopherol which is the only form that is recognized to meet human requirements was selected to study. The analytes (±)- -tocopherol were dissolved in chloroform (CHCl 3 ) and the silver colloid was poured into the compound. Silver colloid was reduced by hydroxylamine hydrochloride. The analytes were the supernatant after standing the mixture for the reason that chloroform have no signals in surface-enhanced Raman scattering in the Ag colloid, and it would not affect the determination of the (±)- -tocopherol. The Normal Raman and SERS spectrum of Vitamin E were contrastively studied to realize how the vitamin E stuck to the silver nanoparticles. The results show the fat-soluble substances can be analysed by SERS. The spectra indicate that the molecules are adsorbed on the surface through the COO- groups by the simultaneous involvement of a and -type coordination. These results suggest some important criteria for consideration in SERS measurements and also provide important insights into the problem of predicting SERS activities for different fat-soluble substances.

  7. Normal Raman and SERS spectroscopy of the vitamin E

    Energy Technology Data Exchange (ETDEWEB)

    Cai Tiantian; Gu Huaimin; Yuan Xiaojuan; Liu Fangfang, E-mail: guhm@scnu.edu.cn [MOE Key Laboratory of Laser Life Science, College of Biophotonics, South China Normal University, 510631, Guangzhou (China)

    2011-01-01

    In this study, surface-enhanced Raman scattering(SERS)spectra of vitamin E were obtained on colloidal silver(Ag). Alpha-(-) tocopherol which is the only form that is recognized to meet human requirements was selected to study. The analytes ({+-})- -tocopherol were dissolved in chloroform (CHCl{sub 3}) and the silver colloid was poured into the compound. Silver colloid was reduced by hydroxylamine hydrochloride. The analytes were the supernatant after standing the mixture for the reason that chloroform have no signals in surface-enhanced Raman scattering in the Ag colloid, and it would not affect the determination of the ({+-})- -tocopherol. The Normal Raman and SERS spectrum of Vitamin E were contrastively studied to realize how the vitamin E stuck to the silver nanoparticles. The results show the fat-soluble substances can be analysed by SERS. The spectra indicate that the molecules are adsorbed on the surface through the COO- groups by the simultaneous involvement of a and -type coordination. These results suggest some important criteria for consideration in SERS measurements and also provide important insights into the problem of predicting SERS activities for different fat-soluble substances.

  8. Analysis of temporal evolution of quantum dot surface chemistry by surface-enhanced Raman scattering.

    Science.gov (United States)

    Doğan, İlker; Gresback, Ryan; Nozaki, Tomohiro; van de Sanden, Mauritius C M

    2016-07-08

    Temporal evolution of surface chemistry during oxidation of silicon quantum dot (Si-QD) surfaces were probed using surface-enhanced Raman scattering (SERS). A monolayer of hydrogen and chlorine terminated plasma-synthesized Si-QDs were spin-coated on silver oxide thin films. A clearly enhanced signal of surface modes, including Si-Clx and Si-Hx modes were observed from as-synthesized Si-QDs as a result of the plasmonic enhancement of the Raman signal at Si-QD/silver oxide interface. Upon oxidation, a gradual decrease of Si-Clx and Si-Hx modes, and an emergence of Si-Ox and Si-O-Hx modes have been observed. In addition, first, second and third transverse optical modes of Si-QDs were also observed in the SERS spectra, revealing information on the crystalline morphology of Si-QDs. An absence of any of the abovementioned spectral features, but only the first transverse optical mode of Si-QDs from thick Si-QD films validated that the spectral features observed from Si-QDs on silver oxide thin films are originated from the SERS effect. These results indicate that real-time SERS is a powerful diagnostic tool and a novel approach to probe the dynamic surface/interface chemistry of quantum dots, especially when they involve in oxidative, catalytic, and electrochemical surface/interface reactions.

  9. Anharmonic effects in IR, Raman, and Raman optical activity spectra of alanine and proline zwitterions.

    Science.gov (United States)

    Danecek, Petr; Kapitán, Josef; Baumruk, Vladimír; Bednárová, Lucie; Kopecký, Vladimír; Bour, Petr

    2007-06-14

    The difference spectroscopy of the Raman optical activity (ROA) provides extended information about molecular structure. However, interpretation of the spectra is based on complex and often inaccurate simulations. Previously, the authors attempted to make the calculations more robust by including the solvent and exploring the role of molecular flexibility for alanine and proline zwitterions. In the current study, they analyze the IR, Raman, and ROA spectra of these molecules with the emphasis on the force field modeling. Vibrational harmonic frequencies obtained with 25 ab initio methods are compared to experimental band positions. The role of anharmonic terms in the potential and intensity tensors is also systematically explored using the vibrational self-consistent field, vibrational configuration interaction (VCI), and degeneracy-corrected perturbation calculations. The harmonic approach appeared satisfactory for most of the lower-wavelength (200-1800 cm(-1)) vibrations. Modern generalized gradient approximation and hybrid density functionals, such as the common B3LYP method, provided a very good statistical agreement with the experiment. Although the inclusion of the anharmonic corrections still did not lead to complete agreement between the simulations and the experiment, occasional enhancements were achieved across the entire region of wave numbers. Not only the transitional frequencies of the C-H stretching modes were significantly improved but also Raman and ROA spectral profiles including N-H and C-H lower-frequency bending modes were more realistic after application of the VCI correction. A limited Boltzmann averaging for the lowest-frequency modes that could not be included directly in the anharmonic calculus provided a realistic inhomogeneous band broadening. The anharmonic parts of the intensity tensors (second dipole and polarizability derivatives) were found less important for the entire spectral profiles than the force field anharmonicities (third

  10. 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

    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 tripl...

  11. Elastic and Raman scattering of 8.5-11.4 MeV photons from 159Tb, 165Ho, and 237Np

    International Nuclear Information System (INIS)

    Bar-Noy, T.; Moreh, R.

    1977-01-01

    Differential cross sections for elastic and inelastic Raman scattering from the deformed heavy nuclei 159 Tb, 165 Ho and 237 Np were measured at five energies between 8.5 and 11.4 MeV. Angular distributions at four angles between 90 0 and 140 0 for both elastic and inelastic scattering at 9.0 and 11.4 MeV were also measured. The monoenergetic photons were obtained from thermal neutron capture in Ni and Cr. All the angular distributions and the elastic and Raman scattering at the higher energies are in good overall agreement with theoretical predictions. The theory is based on a modified simple rotator model of the giant resonance in which the effect of Delbrueck scattering was included. A trend of both the elastic and Raman scattering at lower energies to be stronger than expected are suggested by the data. However, the ratio between the Raman and elastic scattering seem to be in good agreement with theory throughout the whole energy range. This shows that there is no need to introduce a direct nonresonant component to the imaginary part of the elastic scattering amplitude to explain the experimental data. (Auth.)

  12. Resonance Raman and optical dephasing study of tricarbocyanine dyes

    NARCIS (Netherlands)

    Ashworth, SH; Kummrow, A; Lenz, K

    Fluorescence lineshape analysis based on resonance Raman spectra of the dye HITCI was used to determine the details and magnitude of the vibrational part of the line broadening function, Forced light scattering (FLS) was applied to measure optical dephasing of HITCI in ethylene glycol, pumping at

  13. Raman scattering in a two-dimensional Fermi liquid with spin-orbit coupling

    Science.gov (United States)

    Maiti, Saurabh; Maslov, Dmitrii L.

    2017-04-01

    We present a microscopic theory of Raman scattering in a two-dimensional Fermi liquid (FL) with Rashba and Dresselhaus types of spin-orbit coupling and subject to an in-plane magnetic field (B ⃗). In the long-wavelength limit, the Raman spectrum probes the collective modes of such a FL: the chiral spin waves. The characteristic features of these modes are a linear-in-q term in the dispersion and the dependence of the mode frequency on the directions of both q ⃗ and B ⃗. All of these features have been observed in recent Raman experiments on Cd1 -xMnxTe quantum wells.

  14. A novel liquid-filled microstructured polymer optical fiber as bio-sensing platform for Raman spectroscopy

    Science.gov (United States)

    Azkune, Mikel; Arrospide, Eneko; Berganza, Amaia; Bikandi, Iñaki; Aldabaldetreku, Gotzon; Durana, Gaizka; Zubia, Joseba

    2018-02-01

    One approach to overcome the poor efficiency of the Raman scattering as a sensing platform is to use microstructured optical fibers. In this type of fibers with a longitudinal holey structure, light interacts with the target sample, which is confined in the core, giving rise to a light intensity increase of the obtained Raman spectra due to the large interaction distances and the guidance of the scattered light. In this work, we present an ad-hoc fabricated liquid-core microstructured polymer optical fiber (LC-mPOF) as a bio-sensing platform for Raman Spectroscopy. Arising from an initial simulation stage, we create the desired preform using the drilling technique and afterwards the LC-mPOF is drawn in our fiber drawing tower. The guiding mechanism of the light through the solution has a major importance, being a key factor to obtain appreciable enhancements in Raman scattering. In this case, in order to optimize the Raman scattering signal of dissolved glucose (target molecule), we have filled the core with an aqueous solution of the target molecule, enabling in this way the modified total internal reflection mechanism. Experimental Raman measurements are performed and results are discussed.

  15. Fraction of boroxol rings in vitreous boron oxide from a first-principles analysis of Raman and NMR spectra.

    Science.gov (United States)

    Umari, P; Pasquarello, Alfredo

    2005-09-23

    We determine the fraction f of B atoms belonging to boroxol rings in vitreous boron oxide through a first-principles analysis. After generating a model structure of vitreous B2O3 by first-principles molecular dynamics, we address a large set of properties, including the neutron structure factor, the neutron density of vibrational states, the infrared spectra, the Raman spectra, and the 11B NMR spectra, and find overall good agreement with corresponding experimental data. From the analysis of Raman and 11B NMR spectra, we yield consistently for both probes a fraction f of approximately 0.75. This result indicates that the structure of vitreous boron oxide is largely dominated by boroxol rings.

  16. Determination of iron redox ratio in borosilicate glasses and melts from Raman spectra

    Energy Technology Data Exchange (ETDEWEB)

    Cochain, B. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France); Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Neuville, D.R.; Richet, P. [Physique des Mineraux et des Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris Cedex05 (France); Henderson, G.S. [Dept of Geology, University of Toronto, 22 Russell Street, Toronto (Canada); Pinet, O. [SCDV-Laboratoire d' Etudes de Base sur les Verres, CEA Valrho, Centre de Marcoule, 30207 Bagnols-sur-ceze (France)

    2008-07-01

    A method is presented to determine the redox ratio of iron in borosilicate glasses and melts relevant to nuclear waste storage from an analysis of Raman spectra recorded at room or high temperature. The basis of this method is the strong variation of the spectral feature observed between 800 and 1200 cm{sup -1}, in which it is possible to assign a band to vibrational modes involving ferric iron in tetrahedral coordination whose intensity increases with iron content and iron oxidation. After baseline correction and normalization, fits to the Raman spectra made with Gaussian bands enable us to determine the proportion of ferric iron provided the redox ratio is known independently for at least two redox states for a given glass composition. This method is particularly useful for in situ determinations of the kinetics and mechanisms of redox reactions. (authors)

  17. Determination of iron redox ratio in borosilicate glasses and melts from Raman spectra

    International Nuclear Information System (INIS)

    Cochain, B.; Neuville, D.R.; Richet, P.; Henderson, G.S.; Pinet, O.

    2008-01-01

    A method is presented to determine the redox ratio of iron in borosilicate glasses and melts relevant to nuclear waste storage from an analysis of Raman spectra recorded at room or high temperature. The basis of this method is the strong variation of the spectral feature observed between 800 and 1200 cm -1 , in which it is possible to assign a band to vibrational modes involving ferric iron in tetrahedral coordination whose intensity increases with iron content and iron oxidation. After baseline correction and normalization, fits to the Raman spectra made with Gaussian bands enable us to determine the proportion of ferric iron provided the redox ratio is known independently for at least two redox states for a given glass composition. This method is particularly useful for in situ determinations of the kinetics and mechanisms of redox reactions. (authors)

  18. Raman microscopy of freeze-dried mouse eyeball-slice in conjunction with the "in vivo cryotechnique".

    Science.gov (United States)

    Terada, Nobuo; Ohno, Nobuhiko; Saitoh, Sei; Fujii, Yasuhisa; Ohguro, Hiroshi; Ohno, Shinichi

    2007-07-01

    The wavelength of Raman-scattered light depends on the molecular composition of the substance. This is the first attempt to acquire Raman spectra of a mouse eyeball removed from a living mouse, in which the eyeball was preserved using the "in vivo cryotechnique" followed by freeze-drying. Eyeballs were cryofixed using a rapid freezing cryotechnique, and then sliced in the cryostat machine. The slices were sandwiched between glass slides, freeze-dried, and analyzed with confocal Raman microscopy. Important areas including various eyeball tissue layers were selected using bright-field microscopy, and then the Raman spectra were obtained at 240 locations. Four typical patterns of Raman spectra were electronically mapped on the specimen images obtained by the bright-field microscopy. Tissue organization was confirmed by embedding the same eyeball slice used for Raman spectra into epoxy resin and the thick sections were prepared with the inverted capsule method. Each Raman spectral pattern represents a different histological layer in the eyeball which was mapped by comparing the images of toluidine blue staining and Raman mapping with different colors. In the choroid and pigment cell layer, the Raman spectrum had two peaks, corresponding to melanin. Some of the peaks of the Raman spectra obtained from the blood vessels in sclera and the photoreceptor layer were similar to those obtained from the purified hemoglobin and rhodopsin proteins, respectively. Our experimental protocol can distinguish different tissue components with Raman microscopy; therefore, this method can be very useful for examining the distribution of a biological structures and/or chemical components in rapidly frozen freeze-dried tissue.

  19. Raman Optical Activity of Biological Molecules

    Science.gov (United States)

    Blanch, Ewan W.; Barron, Laurence D.

    Now an incisive probe of biomolecular structure, Raman optical activity (ROA) measures a small difference in Raman scattering from chiral molecules in right- and left-circularly polarized light. As ROA spectra measure vibrational optical activity, they contain highly informative band structures sensitive to the secondary and tertiary structures of proteins, nucleic acids, viruses and carbohydrates as well as the absolute configurations of small molecules. In this review we present a survey of recent studies on biomolecular structure and dynamics using ROA and also a discussion of future applications of this powerful new technique in biomedical research.

  20. Label-Free Raman Hyperspectral Imaging of Single Cells Cultured on Polymer Substrates.

    Science.gov (United States)

    Sinjab, Faris; Sicilia, Giovanna; Shipp, Dustin W; Marlow, Maria; Notingher, Ioan

    2017-12-01

    While Raman hyperspectral imaging has been widely used for label-free mapping of biomolecules in cells, these measurements require the cells to be cultured on weakly Raman scattering substrates. However, many applications in biological sciences and engineering require the cells to be cultured on polymer substrates that often generate large Raman scattering signals. Here, we discuss the theoretical limits of the signal-to-noise ratio in the Raman spectra of cells in the presence of polymer signals and how optical aberrations may affect these measurements. We show that Raman spectra of cells cultured on polymer substrates can be obtained using automatic subtraction of the polymer signals and demonstrate the capabilities of these methods in two important applications: tissue engineering and in vitro toxicology screening of drugs. Apart from their scientific and technological importance, these applications are examples of the two most common measurement configurations: (1) cells cultured on an optically thick polymer substrate measured using an immersion/dipping objective; and (2) cells cultured on a transparent polymer substrate and measured using an inverted optical microscope. In these examples, we show that Raman hyperspectral data sets with sufficient quality can be successfully acquired to map the distribution of common biomolecules in cells, such as nucleic acids, proteins, and lipids, as well as detecting the early stages of apoptosis. We also discuss strategies for further improvements that could expand the application of Raman hyperspectral imaging on polymer substrates even further in biomedical sciences and engineering.

  1. Characterization of Few-Layer 1T' MoTe2 by Polarization-Resolved Second Harmonic Generation and Raman Scattering.

    Science.gov (United States)

    Beams, Ryan; Cancado, Luiz Gustavo; Krylyuk, Sergiy; Kalish, Irina; Kalanyan, Berc; Singh, Arunima K; Choudhary, Kamal; Bruma, Alina; Vora, Patrick M; Tavazza, Francesca; Davydov, Albert V; Stranick, Stephan J

    2016-10-05

    We study the crystal symmetry of few-layer 1T' MoTe 2 using the polarization dependence of the second harmonic generation (SHG) and Raman scattering. Bulk 1T' MoTe 2 is known to be inversion symmetric; however, we find that the inversion symmetry is broken for finite crystals with even numbers of layers, resulting in strong SHG comparable to other transition metal dichalcogenides. Group theory analysis of the polarization dependence of the Raman signals allows for the definitive assignment of all the Raman modes in 1T' MoTe 2 and clears up a discrepancy in the literature. The Raman results were also compared with density-functional theory simulations and are in excellent agreement in the layer-depenent variations of the Raman modes. The experimental measurements also determine the relationship between the crystal axes and the polarization-dependence of the SHG and Raman scattering, which now allows the anisotropy of polarized SHG or Raman signal to independently determine the crystal orientation.

  2. Ultrafast stimulated Raman spectroscopy in the near-infrared region

    International Nuclear Information System (INIS)

    Takaya, Tomohisa

    2016-01-01

    A number of electronic transitions in the near-infrared wavelength region are associated with migration or delocalization of electrons in large molecules or molecular systems. Time-resolved near-infrared Raman spectroscopy will be a powerful tool for investigating the structural dynamic of samples with delocalized electrons. However, the sensitivity of near-infrared spontaneous Raman spectrometers is significantly low due to an extremely small probability of Raman scattering and a low sensitivity of near-infrared detectors. Nonlinear Raman spectroscopy is one of the techniques that can overcome the sensitivity problems and enable us to obtain time-resolved Raman spectra in resonance with near-IR transitions. In this article, the author introduces recent progress of ultrafast time-resolved near-infrared stimulated Raman spectroscopy. Optical setup, spectral and temporal resolution, and applications of the spectrometer are described. (author)

  3. Spectral reconstruction for shifted-excitation Raman difference spectroscopy (SERDS).

    Science.gov (United States)

    Guo, Shuxia; Chernavskaia, Olga; Popp, Jürgen; Bocklitz, Thomas

    2018-08-15

    Fluorescence emission is one of the major obstacles to apply Raman spectroscopy in biological investigations. It is usually several orders more intense than Raman scattering and hampers further analysis. In cases where the fluorescence emission is too intense to be efficiently removed via routine mathematical baseline correction algorithms, an alternative approach is needed. One alternative approach is shifted-excitation Raman difference spectroscopy (SERDS), where two Raman spectra are recorded with two slightly different excitation wavelengths. Ideally, the fluorescence emission at the two excitations does not change while the Raman spectrum shifts according to the excitation wavelength. Hence the fluorescence is removed in the difference of the two recorded Raman spectra. For better interpretability a spectral reconstruction procedure is necessary to recover the fluorescence-free Raman spectrum. This is challenging due to the intensity variations between the two recorded Raman spectra caused by unavoidable experimental changes as well as the presence of noise. Existent approaches suffer from drawbacks like spectral resolution loss, fluorescence residual, and artefacts. In this contribution, we proposed a reconstruction method based on non-negative least squares (NNLS), where the intensity variations between the two measurements are utilized in the reconstruction model. The method achieved fluorescence-free reconstruction on three real-world SERDS datasets without significant information loss. Thereafter, we quantified the performance of the reconstruction based on artificial datasets from four aspects: reconstructed spectral resolution, precision of reconstruction, signal-to-noise-ratio (SNR), and fluorescence residual. The artificial datasets were constructed with varied Raman to fluorescence intensity ratio (RFIR), SNR, full-width at half-maximum (FWHM), excitation wavelength shift, and fluorescence variation between the two spectra. It was demonstrated that

  4. Measurement of the Raman scattering cross section of the breathing mode in KDP and DKDP crystals.

    Science.gov (United States)

    Demos, Stavros G; Raman, Rajesh N; Yang, Steven T; Negres, Raluca A; Schaffers, Kathleen I; Henesian, Mark A

    2011-10-10

    The spontaneous Raman scattering cross sections of the main peaks (related to the A1 vibrational mode) in rapid and conventional grown potassium dihydrogen phosphate and deuterated crystals are measured at 532 nm, 355 nm, and 266 nm. The measurement involves the use of the Raman line of water centered at 3400 cm-1 as a reference to obtain relative values of the cross sections which are subsequently normalized against the known absolute value for water as a function of excitation wavelength. This measurement enables the estimation of the transverse stimulated Raman scattering gain of these nonlinear optical materials in various configurations suitable for frequency conversion and beam control in high-power, large-aperture laser systems.

  5. Generation of fast electrons in the external corona of laser plasma by the Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Mašek, Martin; Rohlena, Karel

    2008-01-01

    Roč. 163, 4-6 (2008), 551-558 ISSN 1042-0150 R&D Projects: GA ČR GA202/05/2475 Institutional research plan: CEZ:AV0Z10100523 Keywords : Vlasov equation * stimulated Raman scattering * Raman cascade Subject RIV: BH - Optics, Masers, Lasers Impact factor: 0.415, year: 2008

  6. Raman scattering in three-cation diluted magnetic semiconductor Cd1-x-yMnxMgyTe

    International Nuclear Information System (INIS)

    Agekyan, V.F.; Gridneva, L.K.; Karpov, S.V.; Serov, A.Yu.

    1995-01-01

    Investigations of Raman scattering (RS) in quaternary compounds were conducted to determine and interpret LO and TO frequencies, characterizing CdTe, MnTe, MgTe components in mixed crystal. Raman spectrum in the range of low frequencies is interpreted as interaction of quasi local vibrations with acoustic continuum

  7. Polarized micro-Raman scattering characterization of Mg2Si nanolayers in (001) Si matrix

    International Nuclear Information System (INIS)

    Zlateva, G; Atanassov, A; Baleva, M; Nikolova, L; Abrashev, M V

    2007-01-01

    An orientational growth of the Mg 2 Si lattice relative to the Si lattice is considered assuming minimum mismatch of their lattice parameters. The Raman scattering cross-sections are calculated for the four possible orientations of the Mg 2 Si lattice positioned in this way. The integral intensity ratios for the F 2g mode of Mg 2 Si in different polarization configurations, obtained from the experimental spectra, are compared with the calculated ratios. It is found that the Mg 2 Si nanolayer's morphology is sensitive to the implantation energy, which determines both the peak Mg concentration in the initial implantation profile and its position in the sample depth. At a peak concentration of the order of the stoichiometric concentration, the layers are highly oriented. When the peak concentration is higher and the peak is placed closer to the surface, the layers are polycrystalline

  8. Effects of Zn doping on crystal structure, Raman spectra and superconductivity of SmBa2Cu3O7−δ systems

    International Nuclear Information System (INIS)

    Xue, Renzhong; Dai, Haiyang; Chen, Zhenping; Li, Tao; Xue, Yuncai

    2013-01-01

    Highlights: ► Zn ions affect significantly the lattice parameter of the SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) ceramic. ► Raman spectra of SBCZO samples obviously change with increasing Zn doping content. ► The superconducting transition temperature decreases with increasing Zn content. ► Induced lattice disorder and local magnetic moment in CuO 2 planes are related to suppression of T c . -- Abstract: Polycrystalline SmBa 2 Cu 3−x Zn x O 7−δ (SBCZO) (x = 0.0–0.4) samples are prepared by the usual solid-state reaction technique. The effects of Zn doping on the structure, the grain morphology, Raman spectra and electronic transport properties of SBCZO systems have been investigated. The orthorhombic structure of the samples does not change remarkably. The samples become denser and grain boundary becomes unclear with the increase of Zn content. Raman spectra exhibit different features with increasing Zn content which shows that Zn ions act as strong scattering centers to the charge carriers in the CuO 2 planes, enhance the disorder of the CuO 2 planes and increase oxygen depletion in Cu-O chains. The measurements of the resistivity show that the superconducting transition temperature T c decreases rapidly and the superconducting transition width increases gradually with increasing Zn contents. Furthermore, the changes of the samples’ normal state resistivity from metallic to semi-conducting behavior show the increase of heterogeneities with increasing Zn content which causes inter-grain or intra-grain disorders. All the results suggest that lattice disorder in the CuO 2 planes, the oxygen content change in Cu-O chains and local weak superconductivity regions due to the substitution of Zn for Cu are related to the suppression of T c in the SBCZO systems

  9. Resonance Raman spectra of phthalocyanine monolayers on different supports. A normal mode analysis of zinc phthalocyanine by means of the MNDO method

    NARCIS (Netherlands)

    Palys, Barbara J.; van den Ham, Dirk M.W.; van den Ham, D.M.W.; Briels, Willem J.; Feil, D.; Feil, Dirk

    1995-01-01

    Resonance Raman spectra of monolayers of transition metal phthalocyanines reveal specific interaction with the support. To elucidate its mechanism, Raman spectra of zinc phthalocyanine monolayers were studied. The analysis was based largely on the results of MNDO calculations. Calculated wavenumbers

  10. Light Scattering Spectroscopies of Semiconductor Nanocrystals (Quantum Dots)

    International Nuclear Information System (INIS)

    Yu, Peter Y; Gardner, Grat; Nozaki, Shinji; Berbezier, Isabelle

    2006-01-01

    We review the study of nanocrystals or quantum dots using inelastic light scattering spectroscopies. In particular recent calculations of the phonon density of states and low frequency Raman spectra in Ge nanocrystals are presented for comparison with experimental results

  11. Raman scattering and x-ray diffractometry studies of epitaxial TiO2 and VO2 thin films and multilayers on α-Al2O3(11 bar 20)

    International Nuclear Information System (INIS)

    Foster, C.M.; Chiarello, R.P.; Chang, H.L.M.; You, H.; Zhang, T.J.; Frase, H.; Parker, J.C.; Lam, D.J.

    1993-01-01

    Epitaxial thin films of TiO 2 and VO 2 single layers and TiO 2 /VO 2 multilayers were grown on (11 bar 20) sapphire (α-Al 2 O 3 ) substrates using the metalorganic chemical vapor deposition technique and were characterized using Raman scattering and four x-ray diffractometry. X-ray diffraction results indicate that the films are high quality single crystal material with well defined growth plane and small in-plane and out-of-plane mosaic. Single-layer films are shown to obey the Raman selection rules of TiO 2 and VO 2 single crystals. The close adherence to the Raman selection rules indicates the high degree of orientation of the films, both parallel and perpendicular to the growth plane. Selection rule spectra of two and three layer TiO 2 /VO 2 multilayers are dominated by the VO 2 layers with only minimal signature of the TiO 2 layers. Due to the low band gap of semiconducting vanadium dioxide, we attribute the strong signature of the VO 2 layers to resonant enhancement of the VO 2 Raman component accompanied with absorption of the both the incident and scattered laser light from the TiO 2 layers

  12. Development of fiber lasers and devices for coherent Raman scattering microscopy

    Science.gov (United States)

    Lamb, Erin Stranford

    As ultrafast laser technology has found expanding application in machining, spectroscopy, microscopy, surgery, and numerous other areas, the desire for inexpensive and robust laser sources has grown. Until recently, nonlinear effects in fiber systems due to the tight confinement of the light in the core have limited their performance. However, with advances in managing nonlinearity through pulse propagation physics and the use of large core fibers, the performance of fiber lasers can compete with that of their solid-state counterparts. As specific applications, such as coherent Raman scattering microscopy, emerge that stand to benefit from fiber technology, new performance challenges in areas such as laser noise are anticipated. This thesis studies nonlinear pulse propagation in fiber lasers and fiber parametric devices. Applications of dissipative solitons and self-similar pulse propagation to low-repetition rate oscillators that have the potential to simplify short-pulse amplification schemes will be examined. The rest of this thesis focuses on topics relevant to fiber laser development for coherent Raman scattering microscopy sources. Coherent pulse division and recombination inside the laser cavity will be introduced as an energy-scaling mechanism and demonstrated for a fiber soliton laser. The relative intensity noise properties of mode-locked fiber lasers, with a particular emphasis on normal dispersion lasers, will be explored in simulation and experiment. A fiber optical parametric oscillator will be studied in detail for low noise frequency conversion of picosecond pulses, and its utility for coherent Raman imaging will be demonstrated. Spectral compression of femtosecond pulses is used to generate picosecond pulses to pump this device, and this technique provides a route to future noise reduction in the system. Furthermore, this device forms a multimodal source capable of providing the picosecond pulses for coherent Raman scattering microscopy and the

  13. Raman spectra of Au nanoparticles in polycrystalline LiF film

    International Nuclear Information System (INIS)

    Kurbatova, N.V.; Galyautdinov, M.F.; Stepanov, A.L.; Ivanov, N.A.; Kolesnikov, S.S.; Papernyj, V.L.

    2011-01-01

    The modification of the size of gold nanoparticles in LiF matrix during laser annealing was studied fort he first time by Raman spectroscopy. Laser annealing was carried out at the wavelength of the plasmon absorption of gold nanoparticles. The experimental spectra were compared with the calculated modes of in-phase bending vibrations in nanoparticles. The observed effects were discussed from the standpoint of the size quantization of acoustic vibrations in nanostructures. (authors)

  14. Raman Scattering from Higgs Mode Oscillations in the Two-Dimensional Antiferromagnet Ca_{2}RuO_{4}.

    Science.gov (United States)

    Souliou, Sofia-Michaela; Chaloupka, Jiří; Khaliullin, Giniyat; Ryu, Gihun; Jain, Anil; Kim, B J; Le Tacon, Matthieu; Keimer, Bernhard

    2017-08-11

    We present and analyze Raman spectra of the Mott insulator Ca_{2}RuO_{4}, whose quasi-two-dimensional antiferromagnetic order has been described as a condensate of low-lying spin-orbit excitons with angular momentum J_{eff}=1. In the A_{g} polarization geometry, the amplitude (Higgs) mode of the spin-orbit condensate is directly probed in the scalar channel, thus avoiding infrared-singular magnon contributions. In the B_{1g} geometry, we observe a single-magnon peak as well as two-magnon and two-Higgs excitations. Model calculations using exact diagonalization quantitatively agree with the observations. Together with recent neutron scattering data, our study provides strong evidence for excitonic magnetism in Ca_{2}RuO_{4} and points out new perspectives for research on the Higgs mode in two dimensions.

  15. Boosting the Amount of Molecular Information Through Polarized Resolved Resonance Raman Scattering

    DEFF Research Database (Denmark)

    Hassing, Søren

    2017-01-01

    and near-infrared absorption spectroscopy, i.e. only the spectral distribution is analysed. The goal of the present chapter is to demonstrate that the amount of molecular information (also for solutions and powders) can be increased considerably by analysing also the polarization of the Raman and resonance...... Ramanscattered light. The goal is achieved through: (1) a discussion of the basic properties of Raman scattering with special focus on polarization and polarization dispersion. The discussion includes the rotational invariants of Raman tensors, the non-commuting generator approach to molecular symmetry as a tool...... for construction of state and Raman tensors for single molecules and dimers and higher aggregates and thereby predict the polarization; (2) a discussion of two illustrative case studies: Case study 1: Aggregation of haemoglobin in red blood cells (RBC); and Case study 2: In vitro polarization resolved RRS study...

  16. Picosecond transient backward stimulated Raman scattering and pumping of femtosecond dye lasers

    Science.gov (United States)

    Arrivo, Steven M.; Spears, Kenneth G.; Sipior, Jeffrey

    1995-02-01

    We report studies of transient, backward stimulated, Raman scattering (TBSRS) in solvents with a 10 Hz, 27 ps, 532 nm pump laser. The TBSRS effect was used to create pulses at 545 nm and 630 nm with durations of 2-3 ps and 5-10 μJ of energy. The duration, energy and fluctuations of the Raman pulse were studied as a function of pump energy and focal parameters. A 5 μJ Raman pulse was amplified in either a Raman amplifier or two stage dye amplifier to 1 mJ levels. A 545 nm pulse of 3 ps duration was generated in CCl 4 and was then used to pump a short cavity dye laser (SCDL). The SCDL oscillator and a 5 stage dye amplifier provided a pulse of 700 fs and 400 μJ that was tunable near 590 nm.

  17. Inhibition of stimulated Raman scattering due to the excitation of stimulated Brillouin scattering

    Science.gov (United States)

    Zhao, Yao; Yu, Lu-Le; Weng, Su-Ming; Ren, Chuang; Liu, Chuan-Sheng; Sheng, Zheng-Ming

    2017-09-01

    The nonlinear coupling between stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) of intense laser in underdense plasma is studied theoretically and numerically. Based upon the fluid model, their coupling equations are derived, and a threshold condition of plasma density perturbations due to SBS for the inhibition of SRS is given. Particle-in-cell simulations show that this condition can be achieved easily by SBS in the so-called fluid regime with kLλDDebye length [Kline et al., Phys. Plasmas 13, 055906 (2006)]. SBS can reduce the saturation level of SRS and the temperature of electrons in both homogeneous and inhomogeneous plasma. Numerical simulations also show that this reduced SRS saturation is retained even if the fluid regime condition mentioned above is violated at a later time due to plasma heating.

  18. Efficient "on-the-fly" calculation of Raman spectra from ab-initio molecular dynamics: Application to hydrophobic/hydrophilic solutes in bulk water.

    Science.gov (United States)

    Partovi-Azar, Pouya; Kühne, Thomas D

    2015-11-05

    We present a novel computational method to accurately calculate Raman spectra from first principles. Together with an extension of the second-generation Car-Parrinello method of Kühne et al. (Phys. Rev. Lett. 2007, 98, 066401) to propagate maximally localized Wannier functions together with the nuclei, a speed-up of one order of magnitude can be observed. This scheme thus allows to routinely calculate finite-temperature Raman spectra "on-the-fly" by means of ab-initio molecular dynamics simulations. To demonstrate the predictive power of this approach we investigate the effect of hydrophobic and hydrophilic solutes in water solution on the infrared and Raman spectra. © 2015 Wiley Periodicals, Inc.

  19. Stable isotope ratio measurements in hydrogen, nitrogen, and oxygen using Raman scattering

    International Nuclear Information System (INIS)

    Harney, R.C.; Bloom, S.D.; Milanovich, F.P.

    1975-01-01

    A method for measuring stable isotope ratios using laser Raman scattering was developed which may prove of significant utility and benefit in stable isotope tracer studies. Crude isotope ratio measurements obtained with a low-power laser indicate that with current technology it should be possible to construct an isotope ratio measurement system using laser Raman scattering that is capable of performing 0.1 percent accuracy isotope ratio measurements of 16 O/ 18 O in natural abundance oxygen gas or 14 N/ 15 N in natural abundance nitrogen gas in times less than two minutes per sample. Theory pertinent to the technique, designs of specific isotope ratio spectrometer systems, and data relating to isotope ratio measurements in hydrogen, nitrogen, and oxygen are presented. In addition, the current status of several studies utilizing this technique is discussed. (auth)

  20. Lattice dynamics of CaC.sub.6./sub. by Raman spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Hlinka, Jiří; Gregora, Ivan; Pokorný, Jan; Hérold, C.; Emery, N.; Mareché, J.F.; Lagrange, P.

    2007-01-01

    Roč. 76, č. 14 (2007), 144512/1-144512/6 ISSN 1098-0121 Institutional research plan: CEZ:AV0Z10100520 Keywords : Raman scattering * phonon spectra * CaC 6 * superconductivity Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.172, year: 2007

  1. Theoretical modeling of magnesium ion imprints in the Raman scattering of water.

    Science.gov (United States)

    Kapitán, Josef; Dracínský, Martin; Kaminský, Jakub; Benda, Ladislav; Bour, Petr

    2010-03-18

    Hydration envelopes of metallic ions significantly influence their chemical properties and biological functioning. Previous computational studies, nuclear magnetic resonance (NMR), and vibrational spectra indicated a strong affinity of the Mg(2+) cation to water. We find it interesting that, although monatomic ions do not vibrate themselves, they cause notable changes in the water Raman signal. Therefore, in this study, we used a combination of Raman spectroscopy and computer modeling to analyze the magnesium hydration shell and origin of the signal. In the measured spectra of several salts (LiCl, NaCl, KCl, MgCl(2), CaCl(2), MgBr(2), and MgI(2) water solutions), only the spectroscopic imprint of the hydrated Mg(2+) cation could clearly be identified as an exceptionally distinct peak at approximately 355 cm(-1). The assignment of this band to the Mg-O stretching motion could be confirmed on the basis of several models involving quantum chemical computations on metal/water clusters. Minor Raman spectral features could also be explained. Ab initio and Fourier transform (FT) techniques coupled with the Car-Parrinello molecular dynamics were adapted to provide the spectra from dynamical trajectories. The results suggest that even in concentrated solutions magnesium preferentially forms a [Mg(H(2)O)(6)](2+) complex of a nearly octahedral symmetry; nevertheless, the Raman signal is primarily associated with the relatively strong metal-H(2)O bond. Partially covalent character of the Mg-O bond was confirmed by a natural bond orbital analysis. Computations on hydrated chlorine anion did not provide a specific signal. The FT techniques gave good spectral profiles in the high-frequency region, whereas the lowest-wavenumber vibrations were better reproduced by the cluster models. Both dynamical and cluster computational models provided a useful link between spectral shapes and specific ion-water interactions.

  2. Suppression of resonance Raman scattering via ground state depletion towards sub-diffraction-limited label-free microscopy

    NARCIS (Netherlands)

    Rieger, S.; Fischedick, M.; Boller, Klaus J.; Fallnich, Carsten

    2016-01-01

    We report on the first experimental demonstration of the suppression of spontaneous Raman scattering via ground state depletion. The concept of Raman suppression can be used to achieve sub-diffraction-limited resolution in label-free microscopy by exploiting spatially selective signal suppression

  3. Quantum well effect in bulk PbI(2) crystals revealed by the anisotropy of photoluminescence and Raman spectra.

    Science.gov (United States)

    Baltog, I; Baibarac, M; Lefrant, S

    2009-01-14

    On subjecting a bulk 2H-PbI(2) crystal to vacuum annealing at 500 K followed by a sudden cooling at liquid nitrogen temperature stacking faults are generated that separate distinct layers of nanometric thickness in which different numbers of I-Pb-I atomic layers are bundled together. Such structures, containing two, three, four, five etc I-Pb-I atomic layers, behave as quantum wells of different widths. The signature of such a transformation is given by a shift towards higher energies of the fundamental absorption edge, which is experimentally revealed by specific anisotropies in the photoluminescence and Raman spectra. The quantum confining effect is made visible by specific variations of a wide extra-excitonic band (G) at 2.06 eV that originates in the radiative recombination of carriers (electrons and holes), trapped on the surface defects. The excitation spectrum of the G band, with p polarized exciting light, reveals a fine structure comprised of narrow bands at 2.75, 2.64, 2.59 and 2.56 eV, which are associated with the PbI(2) quantum wells formed from two, three, four and five I-Pb-I atomic layers of 0.7 nm thickness. Regardless of the polarization state of the laser exciting light of 514.5 nm (2.41 eV), which is close to the band gap energy of PbI(2) (2.52 eV), the Raman scattering on bulk as-grown PbI(2) crystals has the character of a resonant process. For p polarized exciting light, the Raman scattering process on vacuum annealed PbI(2) becomes non-resonant. This originates from the quantum well structures generated inside the crystal, whose band gap energies are higher than the energy of the exciting light.

  4. Ag coated microneedle based surface enhanced Raman scattering probe for intradermal measurements

    Science.gov (United States)

    Yuen, Clement; Liu, Quan

    2013-06-01

    We propose a silver coated microneedle to detect test molecules, including R6G and glucose, positioned at a depth of more than 700 μm below a skin phantom surface for mimicking intradermal surface-enhanced Raman scattering measurements.

  5. Raman Spectroscopic Studies of YBa2Cu3O7 Coated Conductors

    International Nuclear Information System (INIS)

    Choi, Mi Kyeung; Mnh, Nguyen Van; Bae, J. S.; Jo, William; Yang, In Sang; Ko, Rock Kil; Ha, Hong Soo; Park, Chan

    2005-01-01

    We present results of Raman spectroscopic studies of superconducting YBa 2 Cu 3 O 7 (YBCO) coated conductors. Raman scattering is used to characterize optical phonon modes, oxygen content, c-axis misalignment, and second phases of the YBCO coated conductors at a micro scale. A two-dimensional mapping of Raman spectra with transport properties has been performed to elucidate the effect of local propertied on current path and superconducting phase. The information taken from the local measurement will be useful for optimizing the process condition.

  6. High temperature phase transition by Raman scattering in SmAlO3

    International Nuclear Information System (INIS)

    Alain, P.; Piriou, B.

    1975-01-01

    Data on the Raman phonon spectra are summarized. Experimental procedure is given. Frequencies and damping coefficients are reported. In spite of coloration and blackbody radiation from the sample, experiments were carried out up to 1,500K [fr

  7. Electronic and local atomistic structure of MgSiO3 glass under pressure: a study of X-ray Raman scattering at the silicon and magnesium L-edges

    Science.gov (United States)

    Fukui, Hiroshi; Hiraoka, Nozomu

    2018-02-01

    We applied X-ray Raman scattering technique to MgSiO3 glass, a precursor to magnesium silicate melts, with respect to magnesium and silicon under high-pressure conditions as well as some polycrystalline phases of MgSiO3 at ambient conditions. We also performed ab initio calculations to interpret the X-ray Raman spectra. Experimentally obtained silicon L-edge spectra indicate that the local environment around silicon started changing at pressure above 10 GPa, where the electronic structure of oxygen is known to change. In contrast, the shape of the magnesium L-edge spectrum changed below 10 GPa. This indicates that the magnesium sites in MgSiO3 glass first distort and that the local structure around magnesium shows a wide variation under pressure. The framework structure consisting of silicon and oxygen changed above 10 GPa, where the coordination number of silicon was more than four. Our results imply that 6-oxygen-coordinated silicon was formed above 20 GPa.

  8. ULTRAVIOLET RAMAN SPECTRAL SIGNATURE ACQUISITION: UV RAMAN SPECTRAL FINGERPRINTS.

    Energy Technology Data Exchange (ETDEWEB)

    SEDLACEK,III, A.J.FINFROCK,C.

    2002-09-01

    As a member of the science-support part of the ITT-lead LISA development program, BNL is tasked with the acquisition of UV Raman spectral fingerprints and associated scattering cross-sections for those chemicals-of-interest to the program's sponsor. In support of this role, the present report contains the first installment of UV Raman spectral fingerprint data on the initial subset of chemicals. Because of the unique nature associated with the acquisition of spectral fingerprints for use in spectral pattern matching algorithms (i.e., CLS, PLS, ANN) great care has been undertaken to maximize the signal-to-noise and to minimize unnecessary spectral subtractions, in an effort to provide the highest quality spectral fingerprints. This report is divided into 4 sections. The first is an Experimental section that outlines how the Raman spectra are performed. This is then followed by a section on Sample Handling. Following this, the spectral fingerprints are presented in the Results section where the data reduction process is outlined. Finally, a Photographs section is included.

  9. Infrared and Raman Spectra of and Isotopomers: A DFT-PT2 Anharmonic Study

    Directory of Open Access Journals (Sweden)

    Andrea Alparone

    2013-01-01

    Full Text Available IR and Raman spectra of selenophene and of its perdeuterated isotopomer have been obtained in gas phase through density-functional theory (DFT computations. Vibrational wavenumbers have been calculated using harmonic and anharmonic second-order perturbation theory (PT2 procedures with the B3LYP method and the 6-311 basis set. Anharmonic overtones have been determined by means of the PT2 method. The introduction of anharmonic terms decreases the harmonic wavenumbers, giving a significantly better agreement with the experimental data. The most significant anharmonic effects occur for the C–H and C–D stretching modes, the observed H/D isotopic wavenumber redshifts being satisfactorily reproduced by the PT2 computations within 6–20 cm−1 (1–3%. In the spectral region between 500 cm−1 and 1500 cm−1, the IR spectra are dominated by the out-of-plane C–H (C–D bending transition, whereas the Raman spectra are mainly characterized by a strong peak mainly attributed to the C=C + C–C bonds stretching vibration with the contribution of the in-plane C–H (C–D bending deformation. The current results confirm that the PT2 approach combined with the B3LYP/6-311 level of calculation is a satisfactory choice for predicting vibrational spectra of cyclic molecules.

  10. Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering.

    Science.gov (United States)

    Palomäki, Emmi; Ahvenainen, Patrik; Ehlers, Henrik; Svedström, Kirsi; Huotari, Simo; Yliruusi, Jouko

    2016-07-11

    In this paper we present a fast model system for monitoring the recrystallization of quench-cooled amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering. The use of these two methods enables comparison between surface and bulk crystallization. Non-ordered mesoporous silica micro-particles were added to the system in order to alter the rate of crystallization of the amorphous xylitol. Raman measurements showed that adding silica to the system increased the rate of surface crystallization, while X-ray measurements showed that the rate of bulk crystallization decreased. Using this model system it is possible to measure fast changes, which occur in minutes or within a few hours. Raman-spectroscopy and wide-angle X-ray scattering were found to be complementary techniques when assessing surface and bulk crystallization of amorphous xylitol. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Raman studies of lanthanum cuprate superconductors

    International Nuclear Information System (INIS)

    Weber, W.H.; Peters, C.R.; Logothetis, E.M.

    1989-01-01

    Raman-scattering studies of the high-T/sub c/ superconductor La/sub 2-//sub x/(Sr, Ba)/sub x/CuO 4 are briefly reviewed. A detailed analysis of the phonon-mode symmetries is given along with a discussion of the effects expected from the orthorhombic-to-tetragonal phase transition, which is known to occur in these materials. Survey spectra are given for powders, ceramics, and single crystals, and an oxide of Cu is identified as the primary impurity phase. Extensive spectra are given from oriented single crystals of La 2 CuO 4 and La/sub 1.85/Sr/sub 0.15/CuO 4 , and several mode assignments are made. Spectra for the high-temperature tetragonal phase and the low-temperature orthorhombic phase are given for each material. The soft phonon associated with the phase transition is seen in La 2 CuO 4 as is a broad peak arising from two-magnon scattering. Neither of these features is seen in the Sr-doped sample

  12. Study on Properties of Energy Spectra of the Molecular Crystals

    Science.gov (United States)

    Pang, Xiao-Feng; Chen, Xiang-Rong

    The energy-spectra of nonlinear vibration of molecular crystals such as acetanilide have been calculated by using discrete nonlinear Schrödinger equation appropriate to the systems, containing various interactions. The energy levels including higher excited states are basically consistent with experimental values obtained by infrared absorption and Raman scattering in acetanilide. We further give the features of distribution of the energy-spectra for the acetanilide. Using the energy spectra we also explained well experimental results obtained by Careri et al..

  13. Polarization Raman spectroscopy of GaN nanorod bundles

    International Nuclear Information System (INIS)

    Tite, T.; Lee, C. J.; Chang, Y.-M.

    2010-01-01

    We performed polarization Raman spectroscopy on single wurtzite GaN nanorod bundles grown by plasma-assisted molecular beam epitaxy. The obtained Raman spectra were compared with those of GaN epilayer. The spectral difference between the GaN nanorod bundles and epilayer reveals the relaxation of Raman selection rules in these GaN nanorod bundles. The deviation of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules is attributed to both the orientation of the crystal axis with respect to the polarization vectors of incident and scattered light and the structural defects in the merging boundary of GaN nanorods. The presence of high defect density induced by local strain at the merging boundary was further confirmed by transmission electron microscopy. The averaged defect interspacing was estimated to be around 3 nm based on the spatial correlation model.

  14. Raman scattering investigation of Bi2Te3 hexagonal nanoplates prepared by a solvothermal process in the absence of NaOH

    International Nuclear Information System (INIS)

    Liang Yujie; Wang Wenzhong; Zeng Baoqing; Zhang Guling; Huang Jing; Li Jin; Li Te; Song Yangyang; Zhang Xiuyu

    2011-01-01

    Research highlights: → Hexagonal Bi 2 Te 3 thin nanoplates were synthesized by a simple solvothermal method. → Optical properties of the nanoplates were investigated by micro-Raman spectroscopy. → Infrared (IR) active mode (A 1u ) is greatly activated in Raman scattering spectrum. → Infrared (IR) active mode (A 1u ) shows up in Raman spectrum of hexagonal nanoplates. → Raman spectrum clearly shows crystal symmetry breaking of hexagonal nanoplates. - Abstract: Hexagonal Bi 2 Te 3 nanoplates were synthesized by a simple solvothermal process in the absence of NaOH. The composition, morphology and size of the as-prepared products were characterized by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM). Raman scattering optical properties of the as-prepared Bi 2 Te 3 nanoplates were investigated by micro-Raman spectroscopy. The Raman spectrum shows that infrared (IR) active mode (A 1u ), which must be odd parity and is Raman forbidden for bulk crystal due to its inversion symmetry, is greatly activated and shown up clearly in Raman scattering spectrum. We attribute the appearance of infrared active (A 1u ) in Raman spectrum to crystal symmetry breaking of Bi 2 Te 3 hexagonal nanoplates. The as-grown Bi 2 Te 3 hexagonal nanoplates, exhibiting novel Raman optical properties compared with bulk crystals, may find potential applications in thermoelectric devices.

  15. Glucose oxidase probe as a surface-enhanced Raman scattering sensor for glucose.

    Science.gov (United States)

    Qi, Guohua; Wang, Yi; Zhang, Biying; Sun, Dan; Fu, Cuicui; Xu, Weiqing; Xu, Shuping

    2016-10-01

    Glucose oxidase (GOx) possessing a Raman-active chromophore (flavin adenine dinucleotide) is used as a signal reporter for constructing a highly specific "turn off" surface-enhanced Raman scattering (SERS) sensor for glucose. This sensing chip is made by the electrostatic assembly of GOx over silver nanoparticle (Ag NP)-functionalized SERS substrate through a positively charged polyelectrolyte linker under the pH of 6.86. To trace glucose in blood serum, owing to the reduced pH value caused by the production of gluconic acid in the GOx-catalyzed oxidation reaction, the bonding force between GOx and polyelectrolyte weakens, making GOx drop off from the sensing chip. As a result, the SERS intensity of GOx on the chip decreases along with the concentration of glucose. This glucose SERS sensor exhibits excellent selectivity based on the specific GOx/glucose catalysis reaction and high sensitivity to 1.0 μM. The linear sensing range is 2.0-14.0 mM, which also meets the requirement on the working range of the human blood glucose detection. Using GOx as a probe shows superiority over other organic probes because GOx almost has no toxicity to the biological system. This sensing mechanism can be applied for intracellular in vivo SERS monitoring of glucose in the future. Graphical abstract Glucose oxidase is used as a Raman signal reporter for constructing a highly specific glucose surface-enhanced Raman scattering (SERS) sensor.

  16. Theoretical study of NMR, infrared and Raman spectra on triple-decker phthalocyanines

    Energy Technology Data Exchange (ETDEWEB)

    Suzuki, Atsushi; Oku, Takeo [Department of Materials Science, The University of Shiga Prefecture 2500 Hassaka, Hikone, Shiga, 522-8533 (Japan)

    2016-02-01

    Electronic structures and magnetic properties of multi-decker phthalocyanines were studied by theoretical calculation. Electronic structures, excited processes at multi-states, isotropic chemical shifts of {sup 13}C, {sup 14}N and {sup 1}H-nuclear magnetic resonance (NMR), principle V-tensor in electronic field gradient (EFG) tensor and asymmetry parameters (η), vibration mode in infrared (IR) and Raman spectra of triple-decker phthalocyanines were calculated by density functional theory (DFT) and time-dependent DFT using B3LYP as basis function. Electron density distribution was delocalized on the phthalocyanine rings with electron static potential. Considerable separation of chemical shifts in {sup 13}C, {sup 14}N and {sup 1}H-NMR was originated from nuclear spin interaction between nitrogen and carbon atoms, nuclear quadrupole interaction based on EFG and η of central metal under crystal field. Calculated optical absorption at multi-excited process was derived from overlapping π-orbital on the phthalocyanine rings. The vibration modes in IR and Raman spectra were based on in-plane deformation and stretching vibrations of metal-ligand coordination bond on the deformed structure.

  17. A sample cell to study hydrate formation with x-ray scattering

    International Nuclear Information System (INIS)

    Conrad, Heiko; Lehmkuehler, Felix; Sternemann, Christian; Feroughi, Omid; Tolan, Metin; Simonelli, Laura; Huotari, Simo

    2009-01-01

    We present a new sample cell for measuring nonresonant inelastic x-ray scattering spectra of a tetrahydrofuran (THF)-water liquid mixture and THF hydrate. The hydrate is formed inside the cell after nucleation seeds have been offered by a special magnetic stirring mechanism. Hydrate formation was verified by wide angle x-ray scattering and nonresonant x-ray Raman scattering spectra at the oxygen K-edge. A broad range of scattering angles can be studied with this cell which is necessary for momentum transfer dependent inelastic x-ray scattering. This cell is ideal to examine other liquid hydrate formers or other liquid samples, which have to be mixed in situ during the measurements.

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

    NARCIS (Netherlands)

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

    2013-01-01

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

  19. Combined use of infrared and Raman spectra in the characterization of orthoclase under various hydrostatic pressures.

    Science.gov (United States)

    Liu, Rui; Wang, Zhi-Hua; Xu, Qiang; Yu, Na; Cao, Miao-Cong

    2014-02-01

    Colorless and pink orthoclase from Balikun granite body, East Zhunger in Xinjiang, served as the samples for the research on hydrostatic pressure experiment. The in-situ hydrostatic pressure test for orthoclases was conducted at the room temperature and pressures from 100 to 600 MPa using cubic zirconia anvil cell, with quartz as pressure gauge. The water located in the orthoclases for the conditions of different hydrostatic pressures was characterized through the methods of Fourier transform infrared (FTIR) and Raman spectra. The results showed that there was a linear correlation between the shifting of Raman bands and hydrostatic pressure applied to the feldspar. All of vibration peaks of M-O structural groups in orthoclases, the bending vibration peaks of Si(Al(IV))-O-Si bond and tetrahedron groups of [SiO4] in Raman spectra shifted toward the higher frequency regularly, the drift distance is 2, 2.19 and less than 2 cm(-1) respectively. The spectra of FTIR suggested that there was more water in colorless orthoclases than the pink one under certain conditions of hydrostatic pressure. The intensity and integral area centered at 3420 cm(-1) in FTIR spectra increased with the rising of hydrostatic pressure. The integral area for colorless and pink feldspar in FTIR spectra rose from 120, 1383 cm(-1) under normal pressure to 1570, 2001 cm(-1) at 600 MPa respectively. The experimental results might indicate that the water in the earth crust could enter the orthoclases in certain condition of the aqueous confining pressure.

  20. Dynamic Volume Holography and Optical Information Processing by Raman Scattering

    International Nuclear Information System (INIS)

    Dodin, I.Y.; Fisch, N.J.

    2002-01-01

    A method of producing holograms of three-dimensional optical pulses is proposed. It is shown that both the amplitude and the phase profile of three-dimensional optical pulse can be stored in dynamic perturbations of a Raman medium, such as plasma. By employing Raman scattering in a nonlinear medium, information carried by a laser pulse can be captured in the form of a slowly propagating low-frequency wave that persists for a time large compared with the pulse duration. If such a hologram is then probed with a short laser pulse, the information stored in the medium can be retrieved in a second scattered electromagnetic wave. The recording and retrieving processes can conserve robustly the pulse shape, thus enabling the recording and retrieving with fidelity of information stored in optical signals. While storing or reading the pulse structure, the optical information can be processed as an analogue or digital signal, which allows simultaneous transformation of three-dimensional continuous images or computing discrete arrays of binary data. By adjusting the phase fronts of the reference pulses, one can also perform focusing, redirecting, and other types of transformation of the output pulses

  1. Shape-dependent surface-enhanced Raman scattering in gold–Raman-probe–silica sandwiched nanoparticles for biocompatible applications

    International Nuclear Information System (INIS)

    Li Ming; Cushing, Scott K; Lankford, Jessica; Wu, Nianqiang; Zhang Jianming; Ma Dongling; Aguilar, Zoraida P

    2012-01-01

    To meet the requirement of Raman probes (labels) for biocompatible applications, a synthetic approach has been developed to sandwich the Raman-probe (malachite green isothiocyanate, MGITC) molecules between the gold core and the silica shell in gold–SiO 2 composite nanoparticles. The gold–MGITC–SiO 2 sandwiched structure not only prevents the Raman probe from leaking out but also improves the solubility of the nanoparticles in organic solvents and in aqueous solutions even with high ionic strength. To amplify the Raman signal, three types of core, gold nanospheres, nanorods and nanostars, have been chosen as the substrates of the Raman probe. The effect of the core shape on the surface-enhanced Raman scattering (SERS) has been investigated. The colloidal nanostars showed the highest SERS enhancement factor while the nanospheres possessed the lowest SERS activity under excitation with 532 and 785 nm lasers. Three-dimensional finite-difference time domain (FDTD) simulation showed significant differences in the local electromagnetic field distributions surrounding the nanospheres, nanorods, and nanostars, which were induced by the localized surface plasmon resonance (LSPR). The electromagnetic field was enhanced remarkably around the two ends of the nanorods and around the sharp tips of the nanostars. This local electromagnetic enhancement made the dominant contribution to the SERS enhancement. Both the experiments and the simulation revealed the order nanostars > nanorods > nanospheres in terms of the enhancement factor. Finally, the biological application of the nanostar–MGITC–SiO 2 nanoparticles has been demonstrated in the monitoring of DNA hybridization. In short, the gold–MGITC–SiO 2 sandwiched nanoparticles can be used as a Raman probe that features high sensitivity, good water solubility and stability, low-background fluorescence, and the absence of photobleaching for future biological applications. (paper)

  2. Inelastic light scattering in crystals

    Science.gov (United States)

    Sushchinskii, M. M.

    The papers presented in this volume are concerned with a variety of problems in optics and solid state physics, such as Raman scattering of light in crystals and disperse media, Rayleigh and inelastic scattering during phase transitions, characteristics of ferroelectrics in relation to the general soft mode concept, and inelastic spectral opalescence. A group-theory approach is used to classify the vibrational spectra of the crystal lattice and to analyze the properties of idealized crystal models. Particular attention is given to surface vibrational states and to the study of the surface layers of crystals and films by light scattering methods.

  3. First-principles simulation of Raman spectra and structural properties of quartz up to 5 GPa

    International Nuclear Information System (INIS)

    Liu Lei; Lv Chao-Jia; Yi Li; Liu Hong; Du Jian-Guo; Zhuang Chun-Qiang

    2015-01-01

    The crystal structure and Raman spectra of quartz are calculated by using first-principles method in a pressure range from 0 to 5 GPa. The results show that the lattice constants (a, c, and V) decrease with increasing pressure and the a-axis is more compressible than the c axis. The Si–O bond distance decreases with increasing pressure, which is in contrast to experimental results reported by Hazen et al. [Hazen R M, Finger L W, Hemley R J and Mao H K 1989 Solid State Communications 725 507–511], and Glinnemann et al. [Glinnemann J, King H E Jr, Schulz H, Hahn T, La Placa S J and Dacol F 1992 Z. Kristallogr. 198 177–212]. The most striking changes are of inter-tetrahedral O–O distances and Si–O–Si angles. The volume of the tetrahedron decreased by 0.9% (from 0 to 5 GPa), which suggests that it is relatively rigid. Vibrational models of the quartz modes are identified by visualizing the associated atomic motions. Raman vibrations are mainly controlled by the deformation of the tetrahedron and the changes in the Si–O–Si bonds. Vibrational directions and intensities of atoms in all Raman modes just show little deviations when pressure increases from 0 to 5 GPa. The pressure derivatives (dν i /dP) of the 12 Raman frequencies are obtained at 0 GPa–5 GPa. The calculated results show that first-principles methods can well describe the high-pressure structural properties and Raman spectra of quartz. The combination of first-principles simulations of the Raman frequencies of minerals and Raman spectroscopy experiments is a useful tool for exploring the stress conditions within the Earth. (paper)

  4. 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}.

  5. The dynamics of molecular dimers in the crystals of m-aminobenzoic acid studied by inelastic neutron scattering (INS), Raman, IR spectroscopy and DFT calculations

    Energy Technology Data Exchange (ETDEWEB)

    Pawlukojc, A.; Leciejewicz, J

    2004-03-29

    Inelastic neutron scattering, Raman and IR spectra were measured for m-aminobenzoic acid (MABA). Optimized geometries and observed frequencies were assigned using DFT calculation on the B3LYP/6-311G** level using Gaussian 98 and Gamess programs. Experimental structural and spectroscopic data are in good agreement with computations assuming the presence in the crystals of molecular dimers composed of two MABA molecules linked by a pair of O-H...O hydrogen bonds each provided by the carboxylic group. INS frequencies have been identified for the O-H (out of plane) mod0008.

  6. Enhanced noise and Raman scattering in plasma

    International Nuclear Information System (INIS)

    Simon, A.; Short, R.W.

    1987-04-01

    Observations of Raman scattering from laser-produced plasma have shown a number of puzzling features. These can be explained by assuming the presence of a bump-on-tail electron distribution created by pulses of fast electrons arising from instabilities at the critical (n/sub c/) or the quarter-critical (n/sub c//4) surface. Experiments using thin foils, in which the target density drops below n/sub c/ and even n/sub c//4 early in the laser pulse, have continued to show the same agreement as is seen for thick targets between the observed Raman spectrum and the predictions of this theory. This raises the issue of the time scale on which such directed pulses of fast electrons can continue to exist in the plasma after their source at n/sub c/ or n/sub c//4 disappears. We show that the classical degradation process is quite slow (of the order of 100 ps or more). Collective processes would appear to broaden and flatten the beam on a faster time scale. However, inclusion of finite spatial size strongly reduces the effect. Furthermore, we will show that broadening of the beam has little effect on the predicted spectrum

  7. Thermal dissociation of molten KHSO4: Temperature dependence of Raman spectra and thermodynamics

    DEFF Research Database (Denmark)

    Knudsen, Christian B.; Kalampounias, Angelos G.; Fehrmann, Rasmus

    2008-01-01

    Raman spectroscopy is used to study the thermal dissociation of molten KHSO4 at temperatures of 240-450 degrees C under static equilibrium conditions. Raman spectra obtained at 10 different temperatures for the molten phase and for the vapors thereof exhibit vibrational wavenumbers and relative...... process taking place to a significant extent in the temperature range of the investigation and for determining its enthalpy to be Delta H degrees = 64.9 +/- 2.9 kJ mol(-1). The importance of these findings for the understanding of the performance of the industrially important sulfuric acid catalyst. under...

  8. Effects of ion beam heating on Raman spectra of single-walled carbon nanotubes

    International Nuclear Information System (INIS)

    Hulman, Martin; Skakalova, Viera; Krasheninnikov, A. V.; Roth, S.

    2009-01-01

    Free standing films of single-wall carbon nanotubes were irradiated with energetic N + and C 4+ ions. The observed changes in the Raman line shape of the radial breathing mode and the G band of the C 4+ irradiated samples were similar to those found for a thermally annealed sample. We ascribe these changes to thermal desorption of volatile dopants from the initially doped nanotubes. A simple geometry of the experiment allows us to estimate the temperature rise by one-dimensional heat conductance equation. The calculation indicates that irradiation-mediated increase in temperature may account for the observed Raman spectra changes

  9. Planar Spontaneous Raman-Scattering Spectroscopy for Reacting Jet-Flow Diagnostics Using Lyot-Ehman Tunable Filter

    Science.gov (United States)

    Sharaborin, D. K.; Markovich, D. M.; Dulin, V. M.

    2018-01-01

    The spatial-density distribution in burning a premixed methane-air swirling turbulent jet has been studied by measuring the intensity of the Stokes branch of spontaneous Raman scattering for vibrational-rotational transitions in nitrogen. An optical system comprising a Nd:YAG laser and the liquid-crystalline Lyot-Ehman tunable filter has been created and tested by measuring the temperature and density fields in a cone-shaped laminar flame. It has been established that the difference of data obtained using the Stokes component of Raman scattering in nitrogen and its ratio to the anti-Stokes component does not exceed 5% in a temperature range from 300 to 1800 K.

  10. Raman spectrum of natural and synthetic stishovite

    Science.gov (United States)

    Hemley, R.J.; Mao, Ho-kwang; Chao, E.C.T.

    1986-01-01

    Raman spectra of natural and synthetic samples of stishovite have been measured with a micro-optical spectrometer system. These spectra have a pattern that is characteristic of rutile-structured oxides. The spectrum of synthetic stishovite is characterized by well-resolved bands at 231, 589, 753, and 967 cm-1, which are assigned as the B1g, Eg, A1g, and B2g fundamentals, respectively, of the first-order Raman spectrum of the ideal, ordered structure. Natural stishovite obtained from Meteor Crater, Arizona has a first-order Raman spectrum that is fully consistent with that of the synthetic material. The observed spectrum of the natural sample, however, is weaker and has bands in addition to those identified as fundamentals in the spectrum of the synthetic material. A broad band at ???475 cm-1 may be indicative of glass or contaminants derived from the extraction procedure. Alternatively, this band may arise from multiphonon scattering that is enhanced by poor crystallinity or structural disorder in the natural shocked sample. ?? 1986 Springer-Verlag.

  11. The MgB2 superconducting energy gaps measured by Raman spectroscopy

    International Nuclear Information System (INIS)

    Quilty, James William

    2003-01-01

    Understanding the nature of the superconducting energy gap in magnesium diboride is an essential part of understanding this unusual superconductor, and Raman scattering is a convenient and powerful technique which is able to directly measure the key physical properties of the gap. The Raman spectra of MgB 2 show clear superconductivity induced renormalisations and evidence is found for two superconducting gaps residing on the σ and π Fermi surfaces with maximum magnitudes of around 110 and 30 cm -1 . The larger gap appears as a sharp peak in the electronic Raman scattering continuum while the smaller gap manifests itself as a threshold in the low-frequency spectral intensity, indicating that the gaps form in different electronic environments. The physical properties of the gaps favour explanations of the extraordinarily high T c in MgB 2 within strong coupling theory

  12. 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 ...

  13. Study of hemoglobin response to mid-ultraviolet (UVB) radiation using micro-Raman spectroscopy

    Science.gov (United States)

    Huang, Y. Y.; Li, N.; Zhou, S. N.; Huang, Z. T.; Zhuang, Z. F.

    2017-09-01

    Confocal micro-Raman spectroscopy is employed to monitor the damage to haemoglobin from mid-ultraviolet (UVB) radiation. We obtained the Raman spectra of an erythrocyte, which indicated that a peroxidation reaction occurs after UVB radiation. Further, the surface enhanced Raman scattering (SERS) spectra of isolated haemoglobin show that the intensities of the 1375 and 1399 cm-1 bands, which are markers of haem aggregation, obviously increase with prolonged UVB irradiation. This increase reveals that haem aggregation occurs in the peroxidation of erythrocytes. The UV-Vis spectra of isolated haemoglobin indicate that the Soret band, which is indicative of excitonic interactions in the aggregated haems, has a redshift ( 12 nm) after 30 min of UVB irradiation of erythrocytes. It can be deduced that an excitonic interaction occurs in the aggregated haems, which is caused by haemoglobin denaturation following UVB irradiation. In addition, the changes of the Raman marker bands during aggregation primarily originate from excitonic interactions. Throughout the process, a higher UVB radiation dose causes greater damage to haemoglobin.

  14. Analysis of albumin Raman scattering in visible and near-infrared ranges

    Science.gov (United States)

    Lykina, Anastasia A.; Artemyev, Dmitry N.

    2018-04-01

    In this work the analysis of the shape and intensity of albumin Raman signals in visible and near-IR ranges was carried out. The experimental setup using lasers from the visible region first of all excites the fluorescence of the albumin solution, the main contribution to which is produced by sodium chloride, which is a component of the tested sample. At the same time, lasers from the near-infrared range excited the Raman signal of albumin most effectively. It was found that the highest ratio of Raman scattering to autofluorescence intensities in the detected signal was obtained using a laser with a wavelength of 1064 nm. To determine the albumin solution concentration by type of spectrum, a regression approach with the projection to latent structures method was applied. The lowest predicted error of albumin concentration of 2-3 g/l was obtained by using the near-infrared range lasers.

  15. In-situ high-temperature Raman spectroscopic studies of aluminosilicate liquids

    Science.gov (United States)

    Daniel, Isabelle; Gillet, Philippe; Poe, Brent T.; McMillan, Paul F.

    1995-03-01

    We have measured in-situ Raman spectra of aluminosilicate glasses and liquids with albite (NaAlSi3 O8) and anorthite (CaAl2Si2O8) compositions at high temperatures, through their glass transition range up to 1700 and 2000 K, respectively. For these experiments, we have used a wire-loop heating device coupled with micro-Raman spectroscopy, in order to achieve effective spatial filtering of the extraneous thermal radiation. A major concern in this work is the development of methodology for reliably extracting the first and second order contributions to the Raman scattering spectra of aluminosilicate glasses and liquids from the high temperature experimental data, and analyzing these in terms of vibrational (anharmonic) and configurational changes. The changes in the first order Raman spectra with temperature are subtle. The principal low frequency band remains nearly constant with increasing temperature, indicating little change in the T-O-T angle, and that the angle bending vibration is quite harmonic. This is in contrast to vitreous SiO2, studied previously. Above Tg, intensity changes in the 560 590 cm-1 regions of both sets of spectra indicate configurational changes in the supercooled liquids, associated with formation of additional Al-O-Al linkages, or 3-membered (Al, Si)-containing rings. Additional intensity at 800 cm-1 reflects also some rearrangement of the Si-O-Al network.

  16. Extracting Optical Fiber Background from Surface-Enhanced Raman Spectroscopy Spectra Based on Bi-Objective Optimization Modeling.

    Science.gov (United States)

    Huang, Jie; Shi, Tielin; Tang, Zirong; Zhu, Wei; Liao, Guanglan; Li, Xiaoping; Gong, Bo; Zhou, Tengyuan

    2017-08-01

    We propose a bi-objective optimization model for extracting optical fiber background from the measured surface-enhanced Raman spectroscopy (SERS) spectrum of the target sample in the application of fiber optic SERS. The model is built using curve fitting to resolve the SERS spectrum into several individual bands, and simultaneously matching some resolved bands with the measured background spectrum. The Pearson correlation coefficient is selected as the similarity index and its maximum value is pursued during the spectral matching process. An algorithm is proposed, programmed, and demonstrated successfully in extracting optical fiber background or fluorescence background from the measured SERS spectra of rhodamine 6G (R6G) and crystal violet (CV). The proposed model not only can be applied to remove optical fiber background or fluorescence background for SERS spectra, but also can be transferred to conventional Raman spectra recorded using fiber optic instrumentation.

  17. 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...

  18. Raman spectra of Nd/Sn cosubstituted Ba6-3xSm8+2xTi18O54 microwave dielectric ceramics

    Science.gov (United States)

    Wu, S. Y.; Li, Y.; Chen, X. M.

    2004-11-01

    The Raman spectra and dielectric properties of Nd /Sn cosubstituted Ba6-3xSm8+2xTi18O54 (x =2/3) microwave dielectric ceramics were discussed as the functions of composition and sintering time. The peaks in 753cm-1 were caused by the second order scatter. The peaks in 425 and 403cm-1 became sharper with prolonging sintering time, and this reflected the increased lattice defects. The shoulder peak near 292cm-1 was caused by the octahedral tilt when A site is Nd3+. The Raman shifts in 590, 520, 280, and 232cm-1 indicated no obvious change in position, but all peaks became sharper with prolonging sintering time. This indicated the increased ordering degree of A-site cations. With prolonging sintering time, the Qf factor (Q is the inverse of dielectric loss, tan δ, and f is the resonant frequency) increased, and the temperature coefficient of resonant frequency significantly decreased or became more negative, while the dielectric constant indicated no significant variation.

  19. Ag/SiO2 surface-enhanced Raman scattering substrate for plasticizer detection

    Science.gov (United States)

    Wu, Ming-Chung; Lin, Ming-Pin; Lin, Ting-Han; Su, Wei-Fang

    2018-04-01

    In this study, we demonstrated a simple method of fabricating a high-performance surface-enhanced Raman scattering (SERS) substrate. Monodispersive SiO2 colloidal spheres were self-assembled on a silicon wafer, and then a silver layer was coated on it to obtain a Ag/SiO2 SERS substrate. The Ag/SiO2 SERS substrates were used to detect three kinds of plasticizer with different concentrations, namely, including bis(2-ethylhexyl)phthalate (DEHP), benzyl butyl phthalate (BBP), and dibutyl phthalate (DBP). The enhancement of Raman scattering intensity caused by surface plasmon resonance can be observed using the Ag/SiO2 SERS substrates. The Ag/SiO2 SERS substrate with a 150-nm-thick silver layer can detect plasticizers, and it satisfies the detection limit of plasticizers at 100 ppm. The developed highly sensitive Ag/SiO2 SERS substrates show a potential for the design and fabrication of functional sensors to identify the harmful plasticizers that plastic products release in daily life.

  20. Enhancement of the stimulated Raman scattering of benzene, acetonitrile and pyridine

    International Nuclear Information System (INIS)

    Munoz, L; Contreras, W A; Cabanzo, R; Aya-RamIrez, O; Mejia-Ospino, E

    2011-01-01

    In this work we used the second harmonic of Nd:YAG laser to observe stimulated Raman scattering (SRS). SRS was observed on benzene, acetonitrile and pyridine using a single shot laser. The SRS radiation is very intense due their laser characteristics, and it is possible to observe several harmonics of different vibrational modes to each molecule studied here.

  1. Investigation of various factors influencing Raman spectra interpretation with the use of likelihood ratio approach.

    Science.gov (United States)

    Michalska, Aleksandra; Martyna, Agnieszka; Zadora, Grzegorz

    2018-01-01

    The main aim of this study was to verify whether selected analytical parameters may affect solving the comparison problem of Raman spectra with the use of the likelihood ratio (LR) approach. Firstly the LR methodologies developed for Raman spectra of blue automotive paints obtained with the use of 785nm laser source (results published by the authors previously) were implemented for good quality spectra recorded for these paints with the use of 514.5nm laser source. For LR models construction two types of variables were used i.e. areas under selected pigments bands and coefficients derived from discrete wavelet transform procedure (DWT). Few experiments were designed for 785nm and 514.5nm Raman spectra databases after constructing well performing LR models (low rates of false positive and false negative answers and acceptable results of empirical cross entropy approach). In order to verify whether objective magnification described by its numerical aperture affects spectra interpretation, three objective magnifications -20×(N.A.=0.4.), 50×(N.A.=0.75) and 100×(N.A.=0.85) within each of the applied laser sources (514.5nm and 785nm) were tested for a group of blue solid and metallic automotive paints having the same sets of pigments depending on the applied laser source. The findings obtained by two types of LR models indicate the importance of this parameter for solving the comparison problem of both solid and metallic automotive paints regardless of the laser source used for measuring Raman signal. Hence, the same objective magnification, preferably 50× (established based on the analysis of within- and between-samples variability and F-factor value), should be used when focusing the laser on samples during Raman measurements. Then the influence of parameters (laser power and time of irradiation) of one of the recommended fluorescence suppression techniques, namely photobleaching, was under investigation. Analysis performed on a group of solid automotive paint

  2. Optical absorption and scattering spectra of pathological stomach tissues

    Science.gov (United States)

    Giraev, K. M.; Ashurbekov, N. A.; Lakhina, M. A.

    2011-03-01

    Diffuse reflection spectra of biotissues in vivo and transmission and reflection coefficients for biotissues in vitro are measured over 300-800 nm. These data are used to determine the spectral absorption and scattering indices and the scattering anisotropy factor for stomach mucous membranes under normal and various pathological conditions (chronic atrophic and ulcerous defects, malignant neoplasms). The most importan tphysiological (hemodynamic and oxygenation levels) and structural-morphological (scatterer size and density) parameters are also determined. The results of a morphofunctional study correlate well with the optical properties and are consistent with data from a histomorphological analysis of the corresponding tissues.

  3. Silver nanoparticles deposited on anodic aluminum oxide template using magnetron sputtering for surface-enhanced Raman scattering substrate

    Energy Technology Data Exchange (ETDEWEB)

    Wong-ek, Krongkamol [Nanoscience and Technology Program, Chulalongkorn University, Bangkok 10330 (Thailand); Eiamchai, Pitak; Horprathum, Mati; Patthanasettakul, Viyapol [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Limnonthakul, Puenisara [Department of Physics, Faculty of Science, King Mongkut' s University of Technology Thonburi, Bangkok 10140 (Thailand); Chindaudom, Pongpan [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand); Nuntawong, Noppadon, E-mail: noppadon.nuntawong@nectec.or.t [National Electronics and Computer Technology Center, 112 Thailand Science Park, Phahonyothin Rd., Klong Luang, Pathumthani 12120 (Thailand)

    2010-09-30

    Low-cost and highly sensitive surface-enhanced Raman scattering (SERS) substrates have been fabricated by a simple anodizing process and a magnetron sputtering deposition. The substrates, which consist of silver nanoparticles embedded on anodic aluminum oxide (AAO) templates, are investigated by a scanning electron microscope and a confocal Raman spectroscopy. The SERS activities are demonstrated by Raman scattering from adsorbed solutions of methylene blue and pyridine on the SERS substrate surface. The most optimized SERS substrate contains the silver nanoparticles, with a size distribution of 10-30 nm, deposited on the AAO template. From a calculation, the SERS enhancement factor is as high as 8.5 x 10{sup 7}, which suggests strong potentials for direct applications in the chemical detection and analyses.

  4. Surface-enhanced Raman scattering on molecular self-assembly in nanoparticle-hydrogel composite.

    Science.gov (United States)

    Miljanić, Snezana; Frkanec, Leo; Biljan, Tomislav; Meić, Zlatko; Zinić, Mladen

    2006-10-24

    Surface-enhanced Raman scattering has been applied to study weak intermolecular interactions between small organic gelling molecules involved in the silver nanoparticle-hydrogel composite formation. Assembly and disassembly of the gelator molecules in close vicinity to embedded silver nanoparticles were followed by changes in Raman intensity of the amide II and carboxyl vibrational bands, whereas the strength of the bands related to benzene modes remained constant. This implied that the gelator molecules were strongly attached to the silver particles through the benzene units, while participating in gel structure organization by intermolecular hydrogen bonding between oxalyl amide and carboxyl groups.

  5. Combining surface enhanced Raman scattering (SERS) and high-performance thin-layer chromatography (HPTLC)

    Science.gov (United States)

    Koglin, E.

    A new method for preparing SERS active surfaces using silver colloidal spheres deposited on HPTLC plates, used for thin-layer chromatography, is discussed in detail. The sensitivity of these activated HPTLC plates is so high that in-situ vibrational investigations of chromatogram spots are possible at the nanogram level. The HPTLC/SERS spectra of purine, benzoic acid and 1-nitro-pyrene adsorbed on silver colloidal activated silica gel plates are measured in the nanogram region. In addition we also report in this paper on the results of a feasibility study performed to evaluate the analytical potential of micro-Raman spectroscopy (triple monochromator, multichannel detection system) in SERS/HPTLC spot characterization. It permits the acquisition of Raman spectra from HPTLC spots down to 1 μm in size or other forms of microsamples approaching the picogram level in mass.

  6. Reassessment of the theory of stimulated Raman scattering

    Science.gov (United States)

    Fralick, G. C.; Deck, R. T.

    1985-01-01

    A modification of the standard theory of stimulated Raman scattering (SRS) first proposed by Sparks (1974, 1975) is analyzed and shown to incorporate a possibly important physical effect; however, its original formulation is incorrect. The analysis is based on an exact numerical integration of the coupled equations of the modified theory, the results of which are compared with both the conventional theory of SRS and with one set of experimental data. A reformulation of the modified theory is suggested that leads to a gain which is in somewhat better agreement with the data than is the conventional theory.

  7. Design and performance of an ultraviolet resonance Raman spectrometer for proteins and nucleic acids.

    Science.gov (United States)

    Russell, M P; Vohník, S; Thomas, G J

    1995-04-01

    We describe an ultraviolet resonance Raman (UVRR) spectrometer appropriate for structural studies of biological macromolecules and their assemblies. Instrument design includes the following features: a continuous wave, intracavity doubled, ultraviolet laser source for excitation of the Raman spectrum; a rotating cell (or jet source) for presentation of the sample to the laser beam; a Cassegrain optic with f/1.0 aperture for collection of the Raman scattering; a quartz prism dispersing element for rejection of stray light and Rayleigh scattering; a 0.75-m single grating monochromator for dispersion of the Raman scattering; and a liquid-nitrogen-cooled, charge-coupled device for detection of the Raman photons. The performance of this instrument, assessed on the basis of the observed signal-to-noise ratios, the apparent resolution of closely spaced spectral bands, and the wide spectrometer bandpass of 2200 cm-1, is believed superior to previously described UVRR spectrometers of similar design. Performance characteristics of the instrument are demonstrated in UVRR spectra obtained from standard solvents, p-ethylphenol, which serves as a model for the tyrosine side chain, the DNA nucleotide deoxyguanosine-5'-monophosphate, and the human tumor necrosis factor binding protein, which is considered representative of soluble globular proteins.

  8. Quantum random bit generation using energy fluctuations in stimulated Raman scattering.

    Science.gov (United States)

    Bustard, Philip J; England, Duncan G; Nunn, Josh; Moffatt, Doug; Spanner, Michael; Lausten, Rune; Sussman, Benjamin J

    2013-12-02

    Random number sequences are a critical resource in modern information processing systems, with applications in cryptography, numerical simulation, and data sampling. We introduce a quantum random number generator based on the measurement of pulse energy quantum fluctuations in Stokes light generated by spontaneously-initiated stimulated Raman scattering. Bright Stokes pulse energy fluctuations up to five times the mean energy are measured with fast photodiodes and converted to unbiased random binary strings. Since the pulse energy is a continuous variable, multiple bits can be extracted from a single measurement. Our approach can be generalized to a wide range of Raman active materials; here we demonstrate a prototype using the optical phonon line in bulk diamond.

  9. One-process fabrication of metal hierarchical nanostructures with rich nanogaps for highly-sensitive surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Liu, Gui-qiang; Yu, Mei-dong; Liu, Zheng-qi; Liu, Xiao-shan; Huang, Shan; Pan, Ping-ping; Wang, Yan; Liu, Mu-lin; Gu, Gang

    2015-01-01

    One-process fabrication of highly active and reproducible surface-enhanced Raman scattering (SERS) substrates via ion beam deposition is reported. The fabricated metal–dielectric–metal (MDM) hierarchical nanostructure possesses rich nanogaps and a tunable resonant cavity. Raman scattering signals of analytes are dramatically strengthened due to the strong near-field coupling of localized surface plasmon resonances (LSPRs) and the strong interaction of LSPRs of metal NPs with surface plasmon polaritons (SPPs) on the underlying metal film by crossing over the dielectric spacer. The maximum Raman enhancement for the highest Raman peak at 1650 cm −1 is 13.5 times greater than that of a single metal nanoparticle (NP) array. Moreover, the SERS activity can be efficiently tailored by varying the size and number of voids between adjacent metal NPs and the thickness of the dielectric spacer. These findings may broaden the scope of SERS applications of MDM hierarchical nanostructures in biomedical and analytical chemistry. (paper)

  10. Studies of the Raman Spectra of Cyclic and Acyclic Molecules: Combination and Prediction Spectrum Methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Taijin; Assary, Rajeev S.; Marshall, Christopher L.; Gosztola, David J.; Curtiss, Larry A.; Stair, Peter C.

    2012-04-02

    A combination of Raman spectroscopy and density functional methods was employed to investigate the spectral features of selected molecules: furfural, 5-hydroxymethyl furfural (HMF), methanol, acetone, acetic acid, and levulinic acid. The computed spectra and measured spectra are in excellent agreement, consistent with previous studies. Using the combination and prediction spectrum method (CPSM), we were able to predict the important spectral features of two platform chemicals, HMF and levulinic acid.The results have shown that CPSM is a useful alternative method for predicting vibrational spectra of complex molecules in the biomass transformation process.

  11. Novel routes to electromagnetic enhancement and its characterisation in surface- and tip-enhanced Raman scattering.

    Science.gov (United States)

    Dawson, P; Frey, D; Kalathingal, V; Mehfuz, R; Mitra, J

    2017-12-04

    Quantitative understanding of the electromagnetic component in enhanced Raman spectroscopy is often difficult to achieve on account of the complex substrate structures utilised. We therefore turn to two structurally simple systems amenable to detailed modelling. The first is tip-enhanced Raman scattering under electron scanning tunnelling microscopy control (STM-TERS) where, appealing to understanding developed in the context of photon emission from STM, it is argued that the localised surface plasmon modes driving the Raman enhancement exist in the visible and near-infrared regime only by virtue of significant modification to the optical properties of the tip and sample metals (gold here). This is due to the strong dc field-induced (∼10 9 V m -1 ) non-linear corrections to the dielectric function of gold via the third order susceptibility term in the polarisation. Also, sub-5 nm spatial resolution is shown in the modelling. Secondly, we suggest a novel deployment of hybrid plasmonic waveguide modes in surface enhanced Raman scattering (HPWG-SERS). This delivers strong confinement of electromagnetic energy in a ∼10 nm oxide 'gap' between a high-index dielectric material of nanoscale width (a GaAs nanorod and a 100 nm Si slab are considered here) and a metal, yielding a monotonic variation in the Raman enhancement factor as a function of wavelength with no long-wavelength cut-off, both features that contrast with STM-TERS.

  12. Fabrication and evolution of multilayer silver nanofilms for surface-enhanced Raman scattering sensing of arsenate

    Directory of Open Access Journals (Sweden)

    Li Jinwei

    2011-01-01

    Full Text Available Abstract Surface-enhanced Raman scattering (SERS has recently been investigated extensively for chemical and biomolecular sensing. Multilayer silver (Ag nanofilms deposited on glass slides by a simple electroless deposition process have been fabricated as active substrates (Ag/GL substrates for arsenate SERS sensing. The nanostructures and layer characteristics of the multilayer Ag films could be tuned by varying the concentrations of reactants (AgNO3/BuNH2 and reaction time. A Ag nanoparticles (AgNPs double-layer was formed by directly reducing Ag+ ions on the glass surfaces, while a top layer (3rd-layer of Ag dendrites was deposited on the double-layer by self-assembling AgNPs or AgNPs aggregates which had already formed in the suspension. The SERS spectra of arsenate showed that characteristic SERS bands of arsenate appear at approximately 780 and 420 cm-1, and the former possesses higher SERS intensity. By comparing the peak heights of the approximately 780 cm-1 band of the SERS spectra, the optimal Ag/GL substrate has been obtained for the most sensitive SERS sensing of arsenate. Using this optimal substrate, the limit of detection (LOD of arsenate was determined to be approximately 5 μg·l-1.

  13. Polarized Raman scattering study of PSN single crystals and epitaxial thin films

    Czech Academy of Sciences Publication Activity Database

    Pokorný, Jan; Rafalovskyi, Iegor; Gregora, Ivan; Borodavka, Fedir; Savinov, Maxim; Drahokoupil, Jan; Tyunina, Marina; Kocourek, Tomáš; Jelínek, Miroslav; Bing, Y.; Ye, Z. -G.; Hlinka, Jiří

    2015-01-01

    Roč. 5, č. 2 (2015), "1550013-1"-"1550013-6" ISSN 2010-135X R&D Projects: GA ČR GA15-04121S; GA ČR GA15-15123S Institutional support: RVO:68378271 Keywords : PSN * relaxors * ferroelectrics * complex perovskites * Raman scattering Subject RIV: BM - Solid Matter Physics ; Magnetism

  14. Theory of Raman scattering by surface polaritons in a four media system

    International Nuclear Information System (INIS)

    Nkoma, J.S.

    1988-08-01

    The method of linear response theory is used to determine the response functions for surface polaritons in a four media system (or bounded bilayer). The dispersion relation is found when the pole of the derived response function vanishes. The expressions for the scattered intensity for both back and forward scattering are derived. The scattered intensity depends on a polarization which is the result of the coupling of the incident light to the vibrational coordinates and electric fields associated with electric-dipole-active lattice vibrations in the bilayer. Expressions for the Raman cross-section by surface polaritons in the four media system are derived for both back and forward scattering. Numerical results are presented by using parameters for a sapphire substrate-(GaP-GaAs) bilayer-vacuum system. (author). 28 refs, 5 figs

  15. Raman study of Ba-doped ceria nanopowders

    Directory of Open Access Journals (Sweden)

    Radović M.

    2007-01-01

    Full Text Available A series of Ce1-xBaxO2-y (5£x£0.20 nanometric powders were synthesized by selfpropagating room temperature synthesis. XRD and Raman scattering measurements were used to characterize the samples at room temperature. All the samples are solid solutions with fluorite type structure with an average crystallite size about 5 nm. The redshift and asymmetric broadening of the Raman F2g mode can be well explained with combined confinement and strain effects because of the nanocrystalline powders nature. The appearance of the additional peaks at ~ 560 cm-1 and ~ 600 cm-1, are attributed to extrinsic and intrinsic O2- vacancies in ceria lattice. Raman spectra of temperature treated Ce0.80Ba0.20O2-d sample revealed the instability of this system.

  16. 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...

  17. Surface enhanced Raman scattering in organic thin films covered with silver, indium and magnesium

    International Nuclear Information System (INIS)

    Salvan, Georgeta; Zahn, Dietrich R.T.; Paez, Beynor

    2004-01-01

    In situ resonant Raman spectroscopy was applied for the investigation of the interface formation between silver, indium and magnesium with polycrystalline organic semiconductor layers of 3,4,9,10-perylene tetra-carboxylic dianhydride (PTCDA). The spectral region of internal as well as external vibrational modes was recorded in order to achieve information related to the chemistry and the structure of the interface as well as to morphology of the metal layer. The experiments benefit from a strong enhancement of the internal mode scattering intensities which is induced by the rough morphology of deposited metals leading to surface enhanced Raman scattering (SERS). The external modes, on the other hand, are attenuated at different rates indicating that the diffusion of the metal atoms into the crystalline layers is highest for indium and lowest for magnesium

  18. Multivariate qualitative analysis of banned additives in food safety using surface enhanced Raman scattering spectroscopy

    Science.gov (United States)

    He, Shixuan; Xie, Wanyi; Zhang, Wei; Zhang, Liqun; Wang, Yunxia; Liu, Xiaoling; Liu, Yulong; Du, Chunlei

    2015-02-01

    A novel strategy which combines iteratively cubic spline fitting baseline correction method with discriminant partial least squares qualitative analysis is employed to analyze the surface enhanced Raman scattering (SERS) spectroscopy of banned food additives, such as Sudan I dye and Rhodamine B in food, Malachite green residues in aquaculture fish. Multivariate qualitative analysis methods, using the combination of spectra preprocessing iteratively cubic spline fitting (ICSF) baseline correction with principal component analysis (PCA) and discriminant partial least squares (DPLS) classification respectively, are applied to investigate the effectiveness of SERS spectroscopy for predicting the class assignments of unknown banned food additives. PCA cannot be used to predict the class assignments of unknown samples. However, the DPLS classification can discriminate the class assignment of unknown banned additives using the information of differences in relative intensities. The results demonstrate that SERS spectroscopy combined with ICSF baseline correction method and exploratory analysis methodology DPLS classification can be potentially used for distinguishing the banned food additives in field of food safety.

  19. Vibrational Imaging with High Sensitivity via Epidetected Coherent Anti-Stokes Raman Scattering Microscopy

    International Nuclear Information System (INIS)

    Volkmer, Andreas; Cheng, Ji-Xin; Sunney Xie, X.

    2001-01-01

    We demonstrate theoretically and experimentally a novel epidetection scheme for coherent anti-Stokes Raman scattering (CARS) microscopy that significantly improves the detection sensitivity. Calculations show that epidetected CARS (E-CARS) signals are present for scatterers smaller than the wavelength of light, whereas the large background signals from the surrounding bulk solvent are suppressed by destructive interference. E-CARS microscopy is capable of revealing small intracellular features that are otherwise buried by the strong water CARS signal

  20. Spectral and far-field broadening due to stimulated rotational Raman scattering driven by the Nike krypton fluoride laser.

    Science.gov (United States)

    Weaver, James; Lehmberg, Robert; Obenschain, Stephen; Kehne, David; Wolford, Matthew

    2017-11-01

    Stimulated rotational Raman scattering (SRRS) in the ultraviolet region (λ=248  nm) has been observed at the Nike laser over extended propagation paths in air during high power operation. Although this phenomenon is not significant for standard operating configurations at Nike, broadening of the laser spectrum and far-field focal profiles has been observed once the intensity-path length product exceeds a threshold of approximately 1  TW/cm. This paper presents experimental results and a new theoretical evaluation of these effects. The observations suggest that significantly broader spectra can be achieved with modest degradation of the final focal distribution. These results point to a possible path for enhanced laser-target coupling with the reduction of laser-plasma instabilities due to broad laser bandwidth produced by the SRRS.

  1. Exploring the chemical enhancement for surface-enhanced Raman scattering with Au bowtie nanoantennas

    International Nuclear Information System (INIS)

    Fromm, David P.; Sundaramurthy, Arvind; Kinkhabwala, Anika; Schuck, P. James; Kino, Gordon S.; Moerner, W.E.

    2006-01-01

    Single metallic bowtie nanoantennas provide a controllable environment for surface-enhanced Raman scattering (SERS) of adsorbed molecules. Bowties have experimentally measured electromagnetic enhancements, enabling estimation of chemical enhancement for both the bulk and the few-molecule regime. Strong fluctuations of selected Raman lines imply that a small number of p-mercaptoaniline molecules on a single bowtie show chemical enhancement >10 7 , much larger than previously believed, likely due to charge transfer between the Au surface and the molecule. This chemical sensitivity of SERS has significant implications for ultra-sensitive detection of single molecules

  2. Ps laser pulse induced stimulated Raman scattering of ammonium nitrate dissolved in water

    Science.gov (United States)

    Kumar, V. Rakesh; Kiran, P. Prem

    2018-04-01

    An intense picosecond laser pulse focused into a liquid medium generates a shock wave in the focal region. This shock wave while propagating into the medium varies the pressure and temperature of the liquid locally leading to the appearance of novel phases which are manifested by the appearance of Raman peaks. We present the phase changes of ammonium nitrate (AN) dissolved in water by studying the forward and backward stimulated Raman Scattering (FSRS and BSRS) signals due to propagation of 30 ps laser pulse induced shockwaves. The dominant peak corresponding to the NO3- symmetric stretching mode is observed with a Raman shift of 1045 cm-1 which represents phase IV of AN with an orthogonal crystalline structure. Apart from this peak, the dominant mode of liquid phase of water with a Raman shift of 3400 cm-1 and an ice VII peak at a Raman shift of 3050 cm-1 confirming the pressure of 10 GPa is observed. The effect of the concentration and input energy on the appearance of the phases will be presented.

  3. Silver-capped silicon nanopillar platforms for adsorption studies of folic acid using surface enhanced Raman spectroscopy and density functional theory

    DEFF Research Database (Denmark)

    Castillo, Jaime; Rindzevicius, Tomas; Wu, Kaiyu

    2015-01-01

    The study of the interactions of folic acid (FA) with surface enhanced Raman scattering substrates is relevant for understanding its adsorption mechanismand for fabricating analytical devices for detection ofmalignant cells over-expressing folate receptors. This paper presents a study of the adso......The study of the interactions of folic acid (FA) with surface enhanced Raman scattering substrates is relevant for understanding its adsorption mechanismand for fabricating analytical devices for detection ofmalignant cells over-expressing folate receptors. This paper presents a study...... of the adsorption of FA on silver-capped silicon nanopillar substrates employing surface enhanced Raman scattering spectroscopy and density functional theory calculations. The experimentally observed vibrations from free FA and FA bound to the Ag surface display different vibrational spectra indicating chemical...

  4. Development of probes for bioanalytic applications of the surface-enhanced Raman scattering; Entwicklung neuer Sonden fuer bioanalytische Anwendungen der oberflaechenverstaerkten Raman-Streuung

    Energy Technology Data Exchange (ETDEWEB)

    Matschulat, Andrea Isabel

    2011-07-01

    Surface-enhanced Raman scattering (SERS) has been established as a versatile tool for probing and labeling in analytical applications, based on the vibrational spectra of samples as well as label molecules in the proximity of noble metal nanostructures. The aim of this work was the construction of novel SERS hybrid probes. The hybrid probes consisted of Au and Ag nanoparticles and reporter molecules, as well as a targeting unit. The concept for the SERS hybrid probe design was followed by experiments comprising characterization techniques such as UV/Vis-spectroscopy (UV/Vis), Transmission electron microscopy (TEM) and Dynamic Light Scattering (DLS), respectively. SERS experiments were performed for studying and optimizing the plasmonic properties of nanoparticles with respect to their enhancement capabilities. The SERS-probes had to meet following requirements: biocompatibility, stability in physiological media, and enhancement of Raman-signals from Raman reporter molecules enabling the identification of different probes even in a complex biological environment. Au and Ag nanoaggregates were found to be the most appropriate SERS substrates for the hybrid probe design. The utilization of Raman reporters enabled the identification of different SERS probes in multiplexing experiments. In particular, the multiplexing capability of ten various reporter molecules para-aminobenzenethiol, 2-naphthalenethiol, crystal violet, rhodamine (B) isothiocyanate, fluorescein isothiocyanate, 5,5'dithiobis(2-nitrobenzoic acid), para-mercaptobenzoic acid, acridine orange, safranine O und nile blue was studied using NIR-SERS excitation. As demonstrated by the results the reporters could be identified through their specific Raman signature even in the case of high structural similarity. Chemical separation analysis of the reporter signatures was performed in a trivariate approach, enabling the discrimination through an automated calculation of specific band ratios. The trivariate

  5. Resonance Raman Spectra of the Transient Cl2 and Br2 Radical Anions

    DEFF Research Database (Denmark)

    Wilbrandt, Robert Walter; Jensen, Niels-Henrik; Sillesen, Alfred Hegaard

    1984-01-01

    The resonance Raman spectra of the short-lived radical anions ClImage 2− and BrImage − in aqueous solution are reported. The observed wavenumbers of 279 cm−1 for ClImage − and 177 cm−1 for BrImage − are about 10% higher than those published for the corresponding species isolated in solid argon ma...

  6. Resonant Raman scattering of ZnS, ZnO, and ZnS/ZnO core/shell quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Milekhin, A.G. [Institute of Semiconductor Physics, Novosibirsk (Russian Federation); Novosibirsk State University, Novosibirsk (Russian Federation); Yeryukov, N.A.; Sveshnikova, L.L.; Duda, T.A. [Institute of Semiconductor Physics, Novosibirsk (Russian Federation); Himcinschi, C. [TU Bergakademie Freiberg, Institut fuer Theoretische Physik, Freiberg (Germany); Zenkevich, E.I. [Belarussian National Technical University, Minsk (Belarus); Zahn, D.R.T. [Chemnitz University of Technology, Semiconductor Physics, Chemnitz (Germany)

    2012-05-15

    Resonant Raman scattering by optical phonon modes as well as their overtones was investigated in ZnS and ZnO quantum dots grown by the Langmuir-Blodgett technique. The in situ formation of ZnS/ZnO core/shell quantum dots was monitored by Raman spectroscopy during laser illumination. (orig.)

  7. Resonant Inverse Compton Scattering Spectra from Highly Magnetized Neutron Stars

    Science.gov (United States)

    Wadiasingh, Zorawar; Baring, Matthew G.; Gonthier, Peter L.; Harding, Alice K.

    2018-02-01

    Hard, nonthermal, persistent pulsed X-ray emission extending between 10 and ∼150 keV has been observed in nearly 10 magnetars. For inner-magnetospheric models of such emission, resonant inverse Compton scattering of soft thermal photons by ultrarelativistic charges is the most efficient production mechanism. We present angle-dependent upscattering spectra and pulsed intensity maps for uncooled, relativistic electrons injected in inner regions of magnetar magnetospheres, calculated using collisional integrals over field loops. Our computations employ a new formulation of the QED Compton scattering cross section in strong magnetic fields that is physically correct for treating important spin-dependent effects in the cyclotron resonance, thereby producing correct photon spectra. The spectral cutoff energies are sensitive to the choices of observer viewing geometry, electron Lorentz factor, and scattering kinematics. We find that electrons with energies ≲15 MeV will emit most of their radiation below 250 keV, consistent with inferred turnovers for magnetar hard X-ray tails. More energetic electrons still emit mostly below 1 MeV, except for viewing perspectives sampling field-line tangents. Pulse profiles may be singly or doubly peaked dependent on viewing geometry, emission locale, and observed energy band. Magnetic pair production and photon splitting will attenuate spectra to hard X-ray energies, suppressing signals in the Fermi-LAT band. The resonant Compton spectra are strongly polarized, suggesting that hard X-ray polarimetry instruments such as X-Calibur, or a future Compton telescope, can prove central to constraining model geometry and physics.

  8. Nanotag-enabled photonic crystal fiber as quantitative surface-enhanced Raman scattering optofluidic platform

    Czech Academy of Sciences Publication Activity Database

    Pinkhasova, P.; Chen, H.; Kaňka, Jiří; Mergo, P.; Du, H.

    2015-01-01

    Roč. 106, č. 7 (2015), 0711061-0711064 ISSN 0003-6951 R&D Projects: GA MŠk(CZ) LH11038 Institutional support: RVO:67985882 Keywords : Photonic crystal fibers * Raman scattering * Crystal whiskers Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.142, year: 2015

  9. Raman excitation profiles of hybrid systems constituted by single-layer graphene and free base phthalocyanine: Manifestations of two mechanisms of graphene-enhanced Raman scattering

    Czech Academy of Sciences Publication Activity Database

    Uhlířová, T.; Mojzeš, P.; Melníková Komínková, Zuzana; Kalbáč, Martin; Sutrová, Veronika; Šloufová, I.; Vlčková, B.

    2017-01-01

    Roč. 48, č. 10 (2017), s. 1270-1281 ISSN 0377-0486 R&D Projects: GA ČR(CZ) GA15-01953S Institutional support: RVO:61388955 ; RVO:61389013 Keywords : graphene-enhanced Raman scattering * single-layer graphene * free base phthalocyanine * Raman excitation profiles * photoinduced charge transfer Subject RIV: CF - Physical ; Theoretical Chemistry; CD - Macromolecular Chemistry (UMCH-V) OBOR OECD: Physical chemistry; Polymer science (UMCH-V) Impact factor: 2.969, year: 2016

  10. Laser Raman Spectroscopic Characterization of Shocked Plagioclase from the Lonar Impact Crater, India.

    Science.gov (United States)

    Chakrabarti, R.; Basu, A. R.; Peterson, J.; Misra, S.

    2004-12-01

    We report Raman spectra of shocked plagioclase grains from the Lonar impact Crater of India. The Lonar Crater, located in the Buldana district of Maharashtra, India (19° 58'N, 76° 31'E), is an almost circular depression in the 65Ma old basalt flows of the Deccan Traps. Age estimates of this impact crater range from 10-50ka. Tektite and basalt samples were collected for this study from the rim of the crater, which is raised about 20 meters above the surrounding plains. For comparison, a Manicouagan maskelynite and an unaltered mid-oceanic ridge basalt with plagioclase laths were also analyzed. Polished thin sections of all these samples were first petrographically studied. The MORB plagioglase as well as the plagioclase from Lonar host-basalts show first order interference colors and distinct multiple lamellar twinning. The Manicouagan maskelynite is isotropic under crossed-polars. The Lonar tektite samples characteristically demonstrate spherules which are identified by their perfectly circular cross-section and isotropic nature. The spherules also contain fragments of the host basalt with plagioclase laths showing lamellar twinning. The groundmass within the spherules shows lath shaped plagioclase grains, most of which show varying degrees of isotropism due to maskelynitization. Raman scattering measurements were performed using the 514.5 nm line of an argon ion laser at an intensity of 40 kW/cm2. An inverted microscope (Nikon TE3000) with 50x objective (NA 0.55) was used for confocal imaging. A holographic notch filter removed residual laser scatter and the Raman scattering was detected by a silicon CCD at -90° C (Princeton Instruments Spec10-400R). Raman spectra were collected from ~250 cm-1 through 2000 cm-1. Raman spectra of crystalline unshocked plagioclase feldspars from the MORB and the Lonar host basalt show strongest peaks at 265 cm-1, 410 cm-1, 510 cm-1 and 1110 cm-1. The results remain the same for different points in a single grain but vary slightly

  11. Raman spectroscopy of Ba(Fe{sub 1−x}Mn{sub x}){sub 2}As{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dias, Fabio Teixeira [Universidade Federal de Pelotas (UFPEL), RS (Brazil); Pinheiro, Lincoln Brum Leite Gusmao [Instituto Federal de Educacao, Ciencia e Tecnologia do Rio Grande do Sul (IFRS), Erechim, RS (Brazil); Jurelo, Alcione Roberto, E-mail: arjurelo@uepg.br [Universidade Estadual de Ponta Grossa (UEPG), PR (Brazil). Departamento de Fisica

    2015-10-01

    Raman scattering measurements on iron–pnictide Mn-doped BaFe{sub 2}As{sub 2} single crystals are reported. Single crystals were grown out of a Fe As self-flux using conventional high-temperature solution growth and characterized by X-ray diffraction, atomic force microscopy, and Raman. Raman spectra were obtained at room temperature and 77 K on ab-and a(b)c-planes. Two of four phonon modes allowed by symmetry were found and identified. It was observed that the scattering intensity of A{sub 1g} mode and the frequencies of the A{sub 1g} and B{sub 1g} phonons are dependent upon doping of Mn. The dependence of scattering intensity and frequency of A{sub 1g} mode on Mn doping might indicate that the Mn ion also occupies the As site. (author)

  12. Raman scattering in orthorhombic CuInS2 nanocrystals

    International Nuclear Information System (INIS)

    Dzhagan, V.M.; Valakh, M.Ya.; Litvinchuk, A.P.; Kruszynska, M.; Kolny-Olesiak, J.; Himcinschi, C.; Zahn, D.R.T.

    2014-01-01

    We report the results of non-resonant and resonant Raman scattering in orthorhombic nanocrystalline CuInS 2 semiconductor, supported by density functional first principle lattice dynamics calculations. A larger number of dominant phonon modes in comparison with standard tetragonal CuInS 2 phases is shown to be associated with peculiarities of cation sublattice ordering and is the ''fingerprint'' of the corresponding structural polymorph. Good overall agreement is found between theoretical and experimental phonon mode frequencies. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  13. FTIR and FT-Raman spectra and density functional computations of the vibrational spectra, molecular geometry and atomic charges of the biomolecule: 5-bromouracil

    Czech Academy of Sciences Publication Activity Database

    Rastogi, V.K.; Palafox, M. A.; Mittal, L.; Peica, N.; Keifer, W.; Lang, Kamil; Ojha, S.P.

    2007-01-01

    Roč. 38, č. 10 (2007), s. 1227-1241 ISSN 0377-0486 Institutional research plan: CEZ:AV0Z40320502 Keywords : FTIR and FT-Raman spectra * density functional computations * molecular geometry Subject RIV: CA - Inorganic Chemistry Impact factor: 3.514, year: 2007

  14. Advanced gamma spectrum processing technique applied to the analysis of scattering spectra for determining material thickness

    International Nuclear Information System (INIS)

    Hoang Duc Tam; VNUHCM-University of Science, Ho Chi Minh City; Huynh Dinh Chuong; Tran Thien Thanh; Vo Hoang Nguyen; Hoang Thi Kieu Trang; Chau Van Tao

    2015-01-01

    In this work, an advanced gamma spectrum processing technique is applied to analyze experimental scattering spectra for determining the thickness of C45 heat-resistant steel plates. The single scattering peak of scattering spectra is taken as an advantage to measure the intensity of single scattering photons. Based on these results, the thickness of steel plates is determined with a maximum deviation of real thickness and measured thickness of about 4 %. Monte Carlo simulation using MCNP5 code is also performed to cross check the results, which yields a maximum deviation of 2 %. These results strongly confirm the capability of this technique in analyzing gamma scattering spectra, which is a simple, effective and convenient method for determining material thickness. (author)

  15. Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400 1400 cm 1

    Science.gov (United States)

    2015-11-24

    Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400...1400 cm‐1 R. L. Aggarwal, L. W. Farrar, S. Di Cecca, and T. H. Jeys MIT Lincoln Laboratory, Lexington, MA 02420‐9108 Raman spectra of...region 400‐1400 cm‐1. A relatively compact (< 2’x2’x2’), sensitive, 532 nm 10 W CW Raman system with double‐pass

  16. Raman Spectra and Cross Sections of Ammonia, Chlorine, Hydrogen Sulfide, Phosgene, and Sulfur Dioxide Toxic Gases in the Fingerprint Region 400-1400 cm-1

    Science.gov (United States)

    2015-12-14

    Raman spectra and cross sections of ammonia, chlorine, hydrogen sulfide, phosgene, and sulfur dioxide toxic gases in the fingerprint region 400...1400 cm‐1 R. L. Aggarwal, L. W. Farrar, S. Di Cecca, and T. H. Jeys MIT Lincoln Laboratory, Lexington, MA 02420‐9108 Raman spectra of...region 400‐1400 cm‐1. A relatively compact (< 2’x2’x2’), sensitive, 532 nm 10 W CW Raman system with double‐pass

  17. In-line balanced detection stimulated Raman scattering microscopy

    KAUST Repository

    Crisafi, Francesco; Kumar, Vikas; Scopigno, Tullio; Marangoni, Marco; Cerullo, Giulio; Polli, Dario

    2017-01-01

    We introduce a novel configuration for stimulated Raman scattering (SRS) microscopy, called In-line Balanced Detection (IBD), which employs a birefringent plate to generate a time-delayed polarization-multiplexed collinear replica of the probe, acting as a reference. Probe and reference cross the sample at the same position, thus maintaining their balance during image acquisition. IBD can be implemented in any conventional SRS setup, by adding a few simple elements, bringing its sensitivity close to the shot-noise limit even with a noisy laser. We tested IBD with a fiber-format laser system and observed signal-to-noise ratio improvement by up to 30 dB.

  18. In-line balanced detection stimulated Raman scattering microscopy

    KAUST Repository

    Crisafi, Francesco

    2017-08-31

    We introduce a novel configuration for stimulated Raman scattering (SRS) microscopy, called In-line Balanced Detection (IBD), which employs a birefringent plate to generate a time-delayed polarization-multiplexed collinear replica of the probe, acting as a reference. Probe and reference cross the sample at the same position, thus maintaining their balance during image acquisition. IBD can be implemented in any conventional SRS setup, by adding a few simple elements, bringing its sensitivity close to the shot-noise limit even with a noisy laser. We tested IBD with a fiber-format laser system and observed signal-to-noise ratio improvement by up to 30 dB.

  19. One-dimensional theory and simulation of acceleration in relativistic electron beam Raman scattering

    International Nuclear Information System (INIS)

    Abe, T.

    1986-01-01

    Raman scattering by a parallel relativistic electron beam was examined analytically and by using the numerical simulation. Incident wave energy can be transferred not only to the scattered electromagnetic wave but also to the beam. That is, the beam can be accelerated by the Doppler-shifted plasma oscillation accompanied by the scattered wave. The energy conversion rates for them were obtained. They increase with the γ value of the electron beam. For the larger γ values of the beam, the energy of the incident wave is mainly transferred to the beam, while in smaller γ, the energy conversion rate to the scattered wave is about 0.2 times that to the beam. Even in smaller γ, the total energy conversion rate is about 0.1

  20. Signal-to-Noise Contribution of Principal Component Loads in Reconstructed Near-Infrared Raman Tissue Spectra

    NARCIS (Netherlands)

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

    The overall quality of Raman spectra in the near-infrared region, where biological samples are often studied, has benefited from various improvements to optical instrumentation over the past decade. However, obtaining ample spectral quality for analysis is still challenging due to device