Science.gov

Sample records for laser raman spectroscopy

  1. Laser tweezers Raman spectroscopy of single cells

    NASA Astrophysics Data System (ADS)

    Chen, De

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

  2. Novel developments in laser diode Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Claps, Ricardo Javier

    2000-11-01

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

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

    PubMed

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

    2015-11-01

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

  4. Raman spectroscopy

    SciTech Connect

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

    1986-04-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2007-04-01

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

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

    PubMed

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

    2007-04-13

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

  8. Laser Raman Spectroscopy in studies of corrosion and electrocatalysis

    SciTech Connect

    Melendres, C.A.

    1988-01-01

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

  9. Femtosecond laser induced nanostructuring for surface enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Messaoudi, H.; Das, S. K.; Lange, J.; Heinrich, F.; Schrader, S.; Frohme, M.; Grunwald, R.

    2014-03-01

    The formation of periodical nanostructures with femtosecond laser pulses was used to create highly efficient substrates for surface-enhanced Raman spectroscopy (SERS). We report about the structuring of silver and copper substrates and their application to the SERS of DNA (herring sperm) and protein molecules (egg albumen). The maximum enhancement factors were found on Ag substrates processed with the second harmonic generation (SHG) of a 1-kHz Ti:sapphire laser and structure periods near the SHG wavelength. In the case of copper, however, the highest enhancement was obtained with long-period ripples induced with at fundamental wavelength. This is explained by an additional significant influence of nanoparticles on the surface. Nanostructured areas in the range of 1.25 mm2 were obtained in 10 s. The surfaces were characterized by scanning electron microscopy, Fast Fourier Transform and Raman spectroscopy. Moreover, the role of the chemical modification of the metal structures is addressed. Thin oxide layers resulting from working in atmosphere which improve the biocompatibility were indicated by vibration spectra. It is expected that the detailed study of the mechanisms of laser-induced nanostructure formation will stimulate further applications of functionalized surfaces like photocatalysis, selective chemistry and nano-biology.

  10. Ring-Down Spectroscopy for Characterizing a CW Raman Laser

    NASA Technical Reports Server (NTRS)

    Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

    2007-01-01

    .A relatively simple technique for characterizing an all-resonant intracavity continuous-wave (CW) solid-state Raman laser involves the use of ring-down spectroscopy. As used here, characterizing signifies determining such parameters as threshold pump power, Raman gain, conversion efficiency, and quality factors (Q values) of the pump and Stokes cavity modes. Heretofore, in order to characterize resonant-cavity-based Raman lasers, it has usually been necessary to manipulate the frequencies and power levels of pump lasers and, in each case, to take several sets of measurements. In cases involving ultra-high-Q resonators, it also has been desirable to lock pump lasers to resonator modes to ensure the quality of measurement data. Simpler techniques could be useful. In the present ring-down spectroscopic technique, one infers the parameters of interest from the decay of the laser out of its steady state. This technique does not require changing the power or frequency of the pump laser or locking the pump laser to the resonator mode. The technique is based on a theoretical analysis of what happens when the pump laser is abruptly switched off after the Raman generation reaches the steady state. The analysis starts with differential equations for the evolution of the amplitudes of the pump and Stokes electric fields, leading to solutions for the power levels of the pump and Stokes fields as functions of time and of the aforementioned parameters. Among other things, these solutions show how the ring-down time depends, to some extent, on the electromagnetic energy accumulated in the cavity. The solutions are readily converted to relatively simple equations for the parameters as functions of quantities that can be determined from measurements of the time-dependent power levels. For example, the steady-state intracavity conversion efficiency is given by G1/G2 1 and the threshold power is given by Pin(G2/G1)2, where Pin is the steady-state input pump power immediately prior to

  11. Laser Diode Raman Spectroscopy Without the Rayleigh Line.

    NASA Astrophysics Data System (ADS)

    Sabbaghzadeh, Jamshid

    1995-01-01

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

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

    PubMed

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

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

  14. Characterization of Phyllosilicates by LIBS and Laser Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, A.; Sobron, P.

    2011-12-01

    NIR spectral signatures of phyllosilicates were recognized on Mars with wide distributions from orbit by OMEGA (on Mars Express orbiter) and CRISM (on Mars Reconnaissance Orbiter) observations. On the ground, geochemical and spectral features related to phyllosilicates were identified in rocks at two locations on Columbia Hill at Gusev crater using the data obtained by the Mars Exploration Rover (MER) Spirit. Furthermore, Opportunity rover is currently approaching the Cap of York at Endeavour crater on Meridiani Planum, where the signatures of phyllosilicates (and hydrous sulfates) were seen by CRISM. Laser-Induced Breakdown spectroscopy (LIBS) and Laser Raman spectroscopy will be used for the first time in rover missions in ChemCam on the NASA-MSL (Mars Science Laboratory) and in RLS on the ESA-ExoMars, respectively. As demonstrated by our previous studies, they are very powerful tools for characterizing the geochemistry and mineralogy aspects of the secondary minerals from aqueous alterations, especially hydrous sulfates. This study investigates the potential of LIBS and Raman spectroscopy for identifying and characterizing a variety of phyllosilicates, especially clays. Clay standards from the Clay Mineral Society were used. The LIBS measurements were made in a Planetary Environment and Analysis Chamber (PEACh) under Mars atmospheric pressure and composition, using 1064 nm as the excitation laser wavelength, same as ChemCam. The Raman measurements were made in ordinary laboratory environment using 532 nm as the excitation wavelength, same as RLS. The LIBS data were processed using custom automated software. We performed quantitative analysis of the spectra in order to evaluate the effectiveness of our method in: (a) discriminating between phyllosilicates and other silicates; (b) classifying different types of phyllosilicates (i.e., serpentine, chlorites, clays); and (c) correlating the LIBS-derived elemental abundances with the real chemical compositions of

  15. Raman Spectroscopy.

    ERIC Educational Resources Information Center

    Gerrard, Donald L.

    1984-01-01

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

  16. Application of pulsed-uv laser Raman spectroscopy to chemical vapor deposition

    SciTech Connect

    Hargis, P.J. Jr.

    1981-01-01

    Raman detection limits obtained with a KrF laser excitation source were comparable to those obtained by laser-induced fluorescence and photofragment emission spectroscopy under chemical vapor deposition conditions.

  17. Raman spectroscopy using 1550 nm (retina-safe) laser excitation.

    PubMed

    Brouillette, Carl; Huang, Hermes; Smith, Wayne; Farquharson, Stuart

    2011-05-01

    During the past decade, the use of portable Raman analyzers for field measurements has grown dramatically. However, most analyzers use 785 nm excitation lasers that can cause permanent eye damage. To overcome this safety concern, we have built a portable Fourier transform (FT) Raman analyzer using a 1550 nm retina-safe excitation laser and have compared its performance to our 1064 nm FT-Raman analyzer, which uses the same optical design. Raman theory predicts approximately five times lower peak intensities at 1550 nm. Although we found that intensities were as much as 20 times less intense, the analyzer is still capable of measuring spectra of sufficient quality to identify and differentiate chemicals. PMID:21513601

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

    SciTech Connect

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

    1993-05-01

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

  19. Rayleigh rejection filters for 193-nm ArF laser Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    Mckenzie, Robert L.

    1993-01-01

    Selected organic absorbers and their solvents are evaluated as spectral filters for the rejection of 193-nm Rayleigh light associated with the use of an ArF excimer laser for Raman spectroscopy. A simply constructed filter cell filled with 0.5 percent acetone in water and an optical path of 7 mm is shown effectively to eliminate stray Rayleigh light underlying the Raman spectrum from air while transmitting 60 percent of the Raman light scattered by O2.

  20. Recent advances in laser tweezers Raman spectroscopy (LTRS) for label-free analysis of single cells.

    PubMed

    Chan, James W

    2013-01-01

    Laser tweezers Raman spectroscopy (LTRS), a technique that integrates optical tweezers with confocal Raman spectroscopy, is a variation of micro-Raman spectroscopy that enables the manipulation and biochemical analysis of single biological particles in suspension. This article provides an overview of the LTRS method, with an emphasis on highlighting recent advances over the past several years in the development of the technology and several new biological and biomedical applications that have been demonstrated. A perspective on the future developments of this powerful cytometric technology will also be presented. PMID:23175434

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

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  2. Shifted excitation Raman difference spectroscopy using a dual-wavelength DBR diode laser at 785 nm

    NASA Astrophysics Data System (ADS)

    Maiwald, M.; Eppich, B.; Fricke, J.; Ginolas, A.; Bugge, F.; Klehr, A.; Sumpf, B.; Erbert, G.; Tränkle, G.

    2015-03-01

    The application of shifted excitation Raman difference spectroscopy (SERDS) using a dual wavelength distributed Bragg reflector (DBR) diode laser at 785 nm will be presented. Both excitation wavelengths necessary for SERDS provide an optical power of more than 160 mW in continuous wave operation. Raman experiments are carried out and demonstrate the suitability of the excitation light source for SERDS. Moreover, a dual-wavelength master-oscillator power amplifier diode laser system is presented. The diode laser system reaches optical powers larger 750 mW while the spectral properties of the dual-wavelength laser remain unchanged.

  3. Raman spectroscopy

    SciTech Connect

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

    1988-06-15

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

  4. Parallel analysis of individual biological cells using multifocal laser tweezers Raman spectroscopy.

    PubMed

    Liu, Rui; Taylor, Douglas S; Matthews, Dennis L; Chan, James W

    2010-11-01

    We report on the development and characterization of a multifocal laser tweezers Raman spectroscopy (M-LTRS) technique for parallel Raman spectral acquisition of individual biological cells. Using a 785-nm diode laser and a time-sharing laser trapping scheme, multiple laser foci are generated to optically trap single polystyrene beads and suspension cells in a linear pattern. Raman signals from the trapped objects are simultaneously projected through the slit of a spectrometer and spatially resolved on a charge-coupled device (CCD) detector with minimal signal crosstalk between neighboring cells. By improving the rate of single-cell analysis, M-LTRS is expected to be a valuable method for studying single-cell dynamics of cell populations and for the development of high-throughput Raman based cytometers. PMID:21073802

  5. Quantitative analysis of essential oils of Thymus daenensis using laser-induced fluorescence and Raman spectroscopy.

    PubMed

    Khoshroo, H; Khadem, H; Bahreini, M; Tavassoli, S H; Hadian, J

    2015-11-10

    Laser-induced fluorescence and Raman spectroscopy are used for the investigation of different genotypes of Thymus daenensis native to the Ilam province of Iran. Different genotypes of T. daenensis essential oils, labeled T1 through T7, possess slight differences with regard to the composition of the thymol. The gas chromatography-mass spectrometry (GC-MS) method is performed to determine the concentration of each constituent as a reference method. The Raman spectra of different concentrations of pure thymol dissolved in hexane as standard samples are obtained via a laboratory prototype Raman spectroscopy setup for the calculation of the calibration curve. The regression coefficient and limit of detection are calculated. The possibility of the differentiation of different genotypes of T. daenensis is also examined by laser-induced fluorescence spectroscopy, although we do not know the exact amounts of their components. All the fluorescence spectral information is used jointly by cluster analysis to differentiate between 7 genotypes. Our results demonstrate the acceptable precision of Raman spectroscopy with GC-MS and corroborate the capacity of Raman spectroscopy in applications in the quantitative analysis field. Furthermore, the cluster analysis results show that laser-induced fluorescence spectroscopy is an acceptable technique for the rapid classification of different genotypes of T. daenensis without having any previous information of their exact amount of constituents. So, the ability to rapidly and nondestructively differentiate between genotypes makes it possible to efficiently select high-quality herbs from many samples. PMID:26560783

  6. Detection of Explosives Using Differential Laser-Induced Perturbation Spectroscopy with a Raman-based Probe.

    PubMed

    Oztekin, Erman K; Burton, Dallas J; Hahn, David W

    2016-04-01

    Explosives detection is carried out with a novel spectral analysis technique referred to as differential laser-induced perturbation spectroscopy (DLIPS) on thin films of TNT, RDX, HMX, and PETN. The utility of Raman spectroscopy for detection of explosives is enhanced by inducing deep ultraviolet laser perturbation on molecular structures in combination with a differential Raman sensing scheme. Principal components analysis (PCA) is used to quantify the DLIPS method as benchmarked against a traditional Raman scattering probe, and the related photo-induced effects on the molecular structure of the targeted explosives are discussed in detail. Finally, unique detection is observed with TNT samples deposited on commonly available background substrates of nylon and polyester. Overall, the data support DLIPS as a noninvasive method that is promising for screening explosives in real-world environments and backgrounds. PMID:26865581

  7. Laser-nanostructured Ag films as substrates for surface-enhanced Raman spectroscopy

    SciTech Connect

    Henley, S.J.; Carey, J.D.; Silva, S.R.P.

    2006-02-20

    Pulsed-laser (248 nm) irradiation of Ag thin films was employed to produce nanostructured Ag/SiO{sub 2} substrates. By tailoring the laser fluence, it was possible to controllably adjust the mean diameter of the resultant near-spherical Ag droplets. Thin films of tetrahedral amorphous carbon (ta-C) were subsequently deposited onto the nanostructured substrates. Visible Raman measurements were performed on the ta-C films, where it was observed that the intensity of the Raman signal was increased by nearly two orders of magnitude, when compared with ta-C films grown on nonstructured substrates. The use of laser annealing as a method of preparing substrates, at low macroscopic temperatures, for surface-enhanced Raman spectroscopy on subnanometer-thick films is discussed.

  8. Lif and Raman Spectroscopy in Undergraduate Labs Using Green Diode-Pumped Solid-State Lasers

    NASA Astrophysics Data System (ADS)

    Gray, Jeffrey A.

    2015-06-01

    Electronic spectroscopy of molecular iodine vapor has long been studied in undergraduate physical chemistry teaching laboratories, but the effectiveness of emission work has typically been limited by availability of instrumentation. This talk shows how to make inexpensive green diode-pumped solid-state (DPSS) lasers easily tunable for efficient, selective excitation of I2. Miniature fiber-optic spectrometers then enable rotationally resolved fluorescence spectroscopy up to v" = 42 near 900 nm with acquisition times of less than one minute. DPSS lasers are also versatile excitation sources for vibrational Raman spectroscopy, which is another common exercise that has been limited by lack of proper instrumentation in the teaching laboratory. This talk shows how to construct a simple accessory for commercial fluorimeters to record vibrational Raman spectra and depolarization ratios for CCl4 and C2Cl4 as part of a lab exercise featuring molecular symmetry.

  9. Investigating Surface Mineralogy, Alteration Processes, and Biomarkers on Mars Using Laser Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Wang, Alian; Jolliff, B. L.; Haskin, L. A.

    2003-01-01

    Despite a wealth of information from past and ongoing missions to Mars, the capability to determine the mineralogy of surface materials and to connect mineralogy with lithologic characteristics that are diagnostic of the environment in which those materials formed remains inadequate. The 2003 Mars Exploration Rovers (MER) will carry a Mini-TES and a Mossbauer spectrometer, which will provide some detailed mineralogy information. For general characterization of minerals and/or biogenic phases (reduced carbon, PAHs, etc) on the surface of Mars, we have been developing a miniaturized laser Raman spectrometer for in situ analyses -- the Mars Microbeam Raman Spectrometer, MMRS. We are also developing strategies to use Raman spectroscopy as a stand-alone technique and to be used synergistically with other in situ analysis methods in future planetary missions. Through studies of Martian meteorites and terrestrial analogs, we are gaining experience of what compositional and structural information can be obtained on key mineral groups using in-situ Raman measurements. We are developing methods for determining mineral proportions in rocks or soils and identifying rock types from sets of closely spaced, rapidly acquired spectra. We are studying how weathering and alteration affect the Raman and luminescence features of minerals and rocks, and we are investigating the Raman characteristics of biogenic organisms and their remains. These studies form the scientific basis for in-situ planetary Raman spectroscopy, and they are being done in parallel with instrument development towards a flight version of the MMRS.

  10. Simultaneous Raman spectroscopy-laser-induced breakdown spectroscopy for instant standoff analysis of explosives using a mobile integrated sensor platform.

    PubMed

    Moros, Javier; Lorenzo, Juan Antonio; Lucena, Patricia; Tobaria, Luciano Miguel; Laserna, José Javier

    2010-02-15

    A novel experimental design combining Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) in a unique integrated sensor is described. The sensor presented herein aims to demonstrate the applicability of a hybrid dual Raman-LIBS system as an analytical tool for the standoff analysis of energetic materials. Frequency-doubled 532 nm Nd:YAG nanosecond laser pulses, first expanded and then focused using a 10x beam expander on targets located at 20 m, allowed simultaneous acquisition of Raman-LIBS spectra for 4-mononitrotoluene (MNT), 2,6-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), C4 and H15 (plastic explosives containing 90% and 75% of RDX by weight, respectively), and Goma2-ECO (Spanish denominated dynamite class high explosive mainly composed of ammonium nitrate, nitroglycol, and dinitrotoluene among other compounds), sodium chlorate, and ammonium nitrate. With the use of a Cassegrain telescope, both Raman and LIBS signals from the same laser pulses were collected and conducted through a bifurcated optical fiber into two identical grating spectrographs coupled to intensified charge-coupled device (iCCD) detectors. With the use of the appropriate timing for each detection mode, adjustment of the laser power on the beam focal conditions is not required. The ability of the present single hybrid sensor to simultaneously acquire, in real time, both molecular and multielemental information from the same laser pulses on the same cross section of the sample at standoff distances greatly enhances the information power of this approach. PMID:20085236

  11. Planetary geochemical investigations using Raman and laser-induced breakdown spectroscopy.

    PubMed

    Clegg, Samuel M; Wiens, Roger; Misra, Anupam K; Sharma, Shiv K; Lambert, James; Bender, Steven; Newell, Raymond; Nowak-Lovato, Kristy; Smrekar, Sue; Dyar, M Darby; Maurice, Sylvestre

    2014-01-01

    An integrated Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) instrument is a valuable geoanalytical tool for future planetary missions to Mars, Venus, and elsewhere. The ChemCam instrument operating on the Mars Curiosity rover includes a remote LIBS instrument. An integrated Raman-LIBS spectrometer (RLS) based on the ChemCam architecture could be used as a reconnaissance tool for other contact instruments as well as a primary science instrument capable of quantitative mineralogical and geochemical analyses. Replacing one of the ChemCam spectrometers with a miniature transmission spectrometer enables a Raman spectroscopy mineralogical analysis to be performed, complementing the LIBS chemical analysis while retaining an overall architecture resembling ChemCam. A prototype transmission spectrometer was used to record Raman spectra under both Martian and Venus conditions. Two different high-pressure and high-temperature cells were used to collect the Raman and LIBS spectra to simulate surface conditions on Venus. The resulting LIBS spectra were used to generate a limited partial least squares Venus calibration model for the major elements. These experiments demonstrate the utility and feasibility of a combined RLS instrument. PMID:25226246

  12. Remote Pulsed Laser Raman Spectroscopy System for Detecting Qater, Ice, and Hydrous Minerals

    NASA Technical Reports Server (NTRS)

    Garcia, Christopher S.; Abedin, M. Nuraul; Sharma, Shiv K.; Misra, Anupam K.; Ismail, Syed; Singh, Upendra; Refaat, Tamer F.; Elsayed-Ali, Hani; Sandford, Steve

    2006-01-01

    For exploration of planetary surfaces, detection of water and ice is of great interest in supporting existence of life on other planets. Therefore, a remote Raman spectroscopy system was demonstrated at NASA Langley Research Center in collaboration with University of Hawaii for detecting ice-water and hydrous minerals on planetary surfaces. In this study, a 532 nm pulsed laser is utilized as an excitation source to allow detection in high background radiation conditions. The Raman scattered signal is collected by a 4-inch telescope positioned in front of a spectrograph. The Raman spectrum is analyzed using a spectrograph equipped with a holographic super notch filter to eliminate Rayleigh scattering, and a holographic transmission grating that simultaneously disperses two spectral tracks onto the detector for higher spectral range. To view the spectrum, the spectrograph is coupled to an intensified charge-coupled device (ICCD), which allows detection of very weak Stokes line. The ICCD is operated in gated mode to further suppress effects from background radiation and long-lived fluorescence. The sample is placed at 5.6 m from the telescope, and the laser is mounted on the telescope in a coaxial geometry to achieve maximum performance. The system was calibrated using the spectral lines of a Neon lamp source. To evaluate the system, Raman standard samples such as calcite, naphthalene, acetone, and isopropyl alcohol were analyzed. The Raman evaluation technique was used to analyze water, ice and other hydrous minerals and results from these species are presented.

  13. Pigment identification in paintings employing laser induced breakdown spectroscopy and Raman microscopy

    NASA Astrophysics Data System (ADS)

    Burgio, L.; Melessanaki, K.; Doulgeridis, M.; Clark, R. J. H.; Anglos, D.

    2001-06-01

    Laser-induced breakdown spectroscopy (LIBS) was used in combination with Raman microscopy, for the identification of pigments in different types of painted works of art. More specifically, a 19th century post-Byzantine icon from Greece and two miniature paintings from France were examined and detailed spectral data are presented which lead to the identification of the pigments used. LIBS measurements yielded information on the presence of pigments or mixtures of pigments based on the characteristic emission from specific elements. Identification of most pigments was performed by Raman microscopy. As demonstrated in this work, the combined use of LIBS and Raman microscopy, two complementary techniques, leads to a detailed characterization of the paintings examined with respect to the pigments used.

  14. Application of laser Raman spectroscopy in concentration measurements of multiple analytes in human body fluids

    NASA Astrophysics Data System (ADS)

    Qu, Jianan Y.; Suria, David; Wilson, Brian C.

    1998-05-01

    The primary goal of these studies was to demonstrate that NIR Raman spectroscopy is feasible as a rapid and reagentless analytic method for clinical diagnostics. Raman spectra were collected on human serum and urine samples using a 785 nm excitation laser and a single-stage holographic spectrometer. A partial east squares method was used to predict the analyte concentrations of interest. The actual concentrations were determined by a standard clinical chemistry. The prediction accuracy of total protein, albumin, triglyceride and glucose in human sera ranged from 1.5 percent to 5 percent which is greatly acceptable for clinical diagnostics. The concentration measurements of acetaminophen, ethanol and codeine inhuman urine have demonstrated the potential of NIR Raman technology in screening of therapeutic drugs and substances of abuse.

  15. Multispectral diode laser based shifted excitation Raman difference spectroscopy for biological sample identification

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

    2012-06-01

    Raman spectroscopy is a well established analytical method with applications in many areas, e.g. analysis of biological samples. To overcome the problem of an undesired fluorescence background masking the Raman signals we present a multi-spectral approach using shifted excitation Raman difference spectroscopy (SERDS). For our investigations we applied microsystem diode lasers which realize two slightly shifted excitation wavelengths required to perform SERDS at 488 nm, 671 nm, and 785 nm. The emission at 488 nm with an optical power of up to 30 mW and a spectral shift of 0.3 nm (12 cm-1) is realized by frequency doubling of a 976 nm distributed feedback (DFB) diode laser. The 671 nm laser diode contains two separate laser cavities (spectral shift: 0.7 nm (13 cm-1)) each incorporating a volume Bragg grating as frequency selective element. In that case, optical powers up to 50 mW can be obtained. For investigations at 785 nm we used a DFB laser with a maximum optical power of 110 mW and a spectral shift of 0.5 nm (7 cm-1). Meat, fat tissue, connective tissue and bones from pork and beef were used as test samples to demonstrate the effective background removal using SERDS. For all three wavelengths integration times of only 5 - 10 seconds were necessary showing the possibility of SERDS for rapid sample identification. A comparison with conventional Raman spectra is given pointing out the improvement of spectral quality. The applicability of SERDS for other analytical applications, e.g. medical diagnosis will be discussed.

  16. Time evolution studies of laser induced chemical changes in InAs nanowire using Raman spectroscopy

    SciTech Connect

    Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka

    2014-07-07

    We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8–16 min. Mixture of metastable oxides like InAsO{sub 4,} As{sub 2}O{sub 3} are formed upon oxidation, which are reflected as sharp Raman peaks at ∼240–254 and 180–200 cm{sup −1}. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

  17. Polarized Raman spectroscopy with differing angles of laser incidence on single-layer graphene

    NASA Astrophysics Data System (ADS)

    Heo, Gaeun; Kim, Yong Seung; Chun, Seung-Hyun; Seong, Maeng-Je

    2015-02-01

    Chemical vapor deposition (CVD)-grown single-layer graphene samples, transferred onto a transmission electron microscope (TEM) grid and onto a quartz plate, were studied using polarized Raman spectroscopy with differing angles of laser incidence ( θ). Two different polarization configurations are used. In an in-plane configuration, the polarization direction of both incident and scattered light is parallel to the graphene plane. In an out-of-plane configuration, the angle between the polarization vector and the graphene plane is the same as the angle of laser incidence ( θ). The normalized Raman intensity of the G-band measured in the out-of-plane configuration, with respect to that in the in-plane configuration, was analyzed as a function of θ. The normalized Raman intensity showed approximately cos2 θ-dependence up to θ = 70°, which can be explained by the fact that only the electric field component of the incident and the scattered photon in the out-of-plane configuration projected onto the graphene plane can contribute to the Raman scattering process because of the perfect confinement of the electrons to the graphene plane.

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

    NASA Astrophysics Data System (ADS)

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

    2001-06-01

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

  19. Raman spectroscopy and microstructure of the pulsed laser-treated silver-anatase thick film

    NASA Astrophysics Data System (ADS)

    Joya, Yasir F.; Joya, K. S.; Bashir, S.; Anwar, A. W.; Rafique, M. S.; Ahmed, Riaz

    2015-09-01

    The present research describes the effect of laser pulses on crystalline titanium dioxide thick film with self-adsorbed silver ions. Anatase film of up to 4 µm thickness was deposited on ITO glass by doctor-blading technique. The film was heated at 450 °C for 60 min and cooled before immersion in silver nitrate aqueous solution. After drying, films were subjected to nanosecond pulses of the excimer laser, and their structural, microstructural and optical properties were investigated. Scanning electron microscopy and EDX analysis revealed the formation of silver nanoparticles (SNPs) dispersed in the anatase matrix. There was no significant change in the anatase structure as revealed by Raman spectroscopy. The intensity of Raman signals from pristine anatase film was increased after the laser treatment of silver ions on the film. This observation is associated with the phenomenon of localized surface plasmon resonance conferred by the crystalline SNPs. The results obtained by the UV-visible spectroscopy also support the role of SNPs to enhance the photoabsorption of the anatase film in the visible region.

  20. Surface-enhanced Raman spectroscopy on laser-engineered ruthenium dye-functionalized nanoporous gold

    NASA Astrophysics Data System (ADS)

    Schade, Lina; Franzka, Steffen; Biener, Monika; Biener, Jürgen; Hartmann, Nils

    2016-06-01

    Photothermal processing of nanoporous gold with a microfocused continuous-wave laser at λ = 532 nm provides a facile means in order engineer the pore and ligament size of nanoporous gold. In this report we take advantage of this approach in order to investigate the size-dependence of enhancement effects in surface-enhanced Raman spectroscopy (SERS). Surface structures with laterally varying pore sizes from 25 nm to ≥200 nm are characterized using scanning electron microscopy and then functionalized with N719, a commercial ruthenium complex, which is widely used in dye-sensitized solar cells. Raman spectroscopy reveals the characteristic spectral features of N719. Peak intensities strongly depend on the pore size. Highest intensities are observed on the native support, i.e. on nanoporous gold with pore sizes around 25 nm. These results demonstrate the particular perspectives of laser-fabricated nanoporous gold structures in fundamental SERS studies. In particular, it is emphasized that laser-engineered porous gold substrates represent a very well defined platform in order to study size-dependent effects with high reproducibility and precision and resolve conflicting results in previous studies.

  1. Raman spectroscopy of ZnMnO thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Orozco, S.; Riascos, H.; Duque, S.

    2016-02-01

    ZnMnO thin films were grown by Pulsed Laser Deposition (PLD) technique onto Silicon (100) substrates at different growth conditions. Thin films were deposited varying Mn concentration, substrate temperature and oxygen pressure. ZnMnO samples were analysed by using Raman Spectroscopy that shows a red shift for all vibration modes. Raman spectra revealed that nanostructure of thin films was the same of ZnO bulk, wurzite hexagonal structure. The structural disorder was manifested in the line width and shape variations of E2(high) and E2(low) modes located in 99 and 434cm-1 respectively, which may be due to the incorporation of Mn ions inside the ZnO crystal lattice. Around 570cm-1 was found a peak associated to E1(LO) vibration mode of ZnO. 272cm-1 suggest intrinsic host lattice defects. Additional mode centred at about 520cm-1 can be overlap of Si and Mn modes.

  2. Technique of laser confocal and Raman spectroscopy for living cell analysis

    NASA Astrophysics Data System (ADS)

    Meng, Xiaochen; Zhu, Lianqing

    2013-10-01

    Because of the shortcomings of the main methods used to analysis single cell, the need of single living cell analysis with no damage, unmarked and in situ dynamic multi-parameter measurement is urgent in the life sciences and biomedical advanced research field. And the method of for living cells analysis is proposed. The spectral pretreatment technology of living cell is the key work of laser confocal Raman spectroscopy. To study the spectrum processing methods for Raman spectrum on single living cell and develop the pre-process techniques to enhance the signal-to-noise ratio, sensitivity, and decrease the influence of fluorescence, elimination the cosmic rays was used to improve the spectrum. The classification, average and filtration of spectrum were applied to enhance signal-to-noise ratio. The fluorescence was depressed for quantity analysis or utilized for analysis by comparing the background and the spectrum. The results show that the proposed technique for laser confocal Raman spectrum of single cell can perform the sensitive and weak intensity peaks and reflect the information of molecules structures very well.

  3. Application of laser tweezers Raman spectroscopy techniques to the monitoring of single cell response to stimuli

    NASA Astrophysics Data System (ADS)

    Chan, James W.; Liu, Rui; Matthews, Dennis L.

    2012-06-01

    Laser tweezers Raman spectroscopy (LTRS) combines optical trapping with micro-Raman spectroscopy to enable label-free biochemical analysis of individual cells and small biological particles in suspension. The integration of the two technologies greatly simplifies the sample preparation and handling of suspension cells for spectroscopic analysis in physiologically meaningful conditions. In our group, LTRS has been used to study the effects of external perturbations, both chemical and mechanical, on the biochemistry of the cell. Single cell dynamics can be studied by performing longitudinal studies to continuously monitor the response of the cell as it interacts with its environment. The ability to carry out these measurements in-vitro makes LTRS an attractive tool for many biomedical applications. Here, we discuss the use of LTRS to study the response of cancer cells to chemotherapeutics and bacteria cells to antibiotics and show that the life cycle and apoptosis of the cells can be detected. These results show the promise of LTRS for drug discovery/screening, antibiotic susceptibility testing, and chemotherapy response monitoring applications. In separate experiments, we study the response of red blood cells to the mechanical forces imposed on the cell by the optical tweezers. A laser power dependent deoxygenation of the red blood cell in the single beam trap is reported. Normal, sickle cell, and fetal red blood cells have a different behavior that enables the discrimination of the cell types based on this mechanochemical response. These results show the potential utility of LTRS for diagnosing and studying red blood cell diseases.

  4. Near-field Raman spectroscopy of biological nanomaterials by in situ laser-induced synthesis of tip-enhanced Raman spectroscopy tips.

    PubMed

    Sinjab, Faris; Lekprasert, Banyat; Woolley, Richard A J; Roberts, Clive J; Tendler, Saul J B; Notingher, Ioan

    2012-06-15

    We report a new approach in tip-enhanced Raman spectroscopy (TERS) in which TERS-active tips with enhancement factors of ∼10(-5)× can be rapidly (1-3 min) produced in situ by laser-induced synthesis of silver nanoparticles at the tip apex. The technique minimizes the risks of tip contamination and damage during handling and provides in situ feedback control, which allows the prediction of the tip performance. We show that TERS tips produced by this technique enable the measurement of spatially resolved TERS spectra of self-assembled peptide nanotubes with a spatial resolution of ∼20  nm. PMID:22739873

  5. Pulsed laser Raman spectroscopy in the laser-heated diamond anvil cell

    SciTech Connect

    Goncharov, A F; Crowhurst, J C

    2005-03-24

    We describe the design and operation of a spatially-filtered Raman/fluorescence spectrometer that incorporates a pulsed 532 nm laser excitation source and a synchronized and electronically gated CCD detector. This system permits the suppression of undesired continuous radiation from various sources by a factor of up to 50,000 providing the possibility of acquiring Raman signals at temperatures exceeding 5,000 K. We present performance comparisons of this system with that of a state-of-the-art conventional CW system using a 458 nm excitation source. We also demonstrate that the pulsed system is capable of suppressing an impurity-induced (single nitrogen defects) fluorescence in diamond, and further suggest that this capability can be used to suppress the stress-induced fluorescence in diamond that may appear at pressures near or above 150 GPa.

  6. Characterisation of Diamond-Like Carbon (DLC) laser targets by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Haddock, D.; Parker, T.; Spindloe, C.; Tolley, M.

    2016-04-01

    The search for target materials suitable for High Power Laser Experiments at ultralow thicknesses (below ten nanometres) is ongoing. Diamond-Like Carbon is investigated as an answer for a low-Z material that can survive target chamber pump-down and laser prepulse. DLC was produced using Plasma-Enhanced Chemical Vapour Deposition, using with varying gas flow mixtures of argon and methane. The methane plasma deposits amorphous carbon onto the substrate and the argon plasma re-sputters the weakly bonded carbon leaving a high proportion of diamond-like bonding. Bonding natures were probed using Raman spectroscopy; analysis of the resulting spectrum showed that flow rates of 40sccm/60sccm methane to argon produced DLC films with a diamond-like (sp 3) content of ∼20%. Increasing the methane gas flow decreased this value to less than 5%. DLC foils were processed into laser targets by method of float off; using a sodium chloride release layer and lowering into water, this was then lifted onto an array of apertures allowing for laser irradiation of the material with no backing. DLC with 20% sp 3 content showed superior yield when compared to other materials such as metals and some plastics of the same thickness, with ∼70% of the target positions surviving the float off procedure at <10nm. As a result of this work DLC targets have been available for a number of experiments at the Central Laser Facility.

  7. Remote Raman - laser induced breakdown spectroscopy (LIBS) geochemical investigation under Venus atmospheric conditions

    SciTech Connect

    Clegg, Sanuel M; Barefield, James E; Humphries, Seth D; Wiens, Roger C; Vaniman, D. T.; Sharma, S. K.; Misra, A. K.; Dyar, M. D.; Smrekar, S. E.

    2010-12-13

    The extreme Venus surface temperatures ({approx}740 K) and atmospheric pressures ({approx}93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical science goals without the risks associated with collecting samples and bringing them into the lander. Wiens et al. and Sharma et al. demonstrated that both analytical techniques can be integrated into a single instrument capable of planetary missions. The focus of this paper is to explore the capability to probe geologic samples with Raman - LIBS and demonstrate quantitative analysis under Venus surface conditions. Raman and LIBS are highly complementary analytical techniques capable of detecting both the mineralogical and geochemical composition of Venus surface materials. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from Soviet Venera and VEGA landers that collectively suggest a surface composition that is primarily tholeiitic basaltic with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. These landers were not equipped to probe the surface mineralogy as can be accomplished with Raman spectroscopy. Based on the observed compositional differences and recognizing the imprecise nature of the existing data, 15 samples were chosen to constitute a Venus-analog suite for this study, including five basalts, two each of andesites, dacites, and sulfates, and single samples of a foidite, trachyandesite, rhyolite, and basaltic trachyandesite under Venus conditions. LIBS data reduction involved generating a partial least squares (PLS) model with a subset of the rock powder standards to

  8. Laser flash-Raman spectroscopy method for the measurement of the thermal properties of micro/nano wires.

    PubMed

    Liu, Jinhui; Wang, Haidong; Hu, Yudong; Ma, Weigang; Zhang, Xing

    2015-01-01

    This paper introduces a new method for measuring the thermal diffusivity and thermal conductivity of individual micro/nano wires using Raman spectroscopy. This method uses a focused short pulsed laser and a continuous-wave laser in a Raman spectroscopy system as the local heater, Raman signal excitation source, and temperature sensor. Unsteady and steady thermal conduction models are used to get two independent equations for the thermal diffusivity (α) and laser absorptivity (η). This new method is verified by comparing experimental results for graphite carbon fiber with measurement using the 3ω method. The method was then used to measure the temperature dependent thermal diffusivity and thermal conductivity of individual carbon nanotubes. PMID:25638107

  9. Intracavity Raman lasers

    SciTech Connect

    Band, Y.B.; Ackerhalt, J.R.; Krasinski, J.S.; Heller, D.F.

    1989-02-01

    Experimental and theoretical studies of intracavity Raman lasers are presented. Advantages of intracavity Raman lasers, particularly for low-emission cross section and broadly tunable vibronic gain media, are described. Experimental studies of a hydrogen gas Raman laser pumped inside the cavity of an alexandrite laser are presented. A theoretical model of the dynamics of a unidirectional intracavity Raman ring laser is developed and solved analytically. This model is adapted to simulate experiments.

  10. UV Raman spectroscopy of H2-air flames excited with a narrowband KrF laser

    NASA Technical Reports Server (NTRS)

    Shirley, John A.

    1990-01-01

    Raman spectra of H2 and H2O in flames excited by a narrowband KrF excimer laser are reported. Observations are made over a porous-plug, flat-flame burner reacting H2 in air, fuel-rich with nitrogen dilution to control the temperature, and with an H2 diffusion flame. Measurements made from UV Raman spectra show good agreement with measurements made by other means, both for gas temperature and relative major species concentrations. Laser-induced fluorescence interferences arising from OH and O2 are observed in emission near the Raman spectra. These interferences do not preclude Raman measurements, however.

  11. Monitoring Dynamic Protein Expression in Single Living E. Coli. Bacterial Cells by Laser Tweezers Raman Spectroscopy

    SciTech Connect

    Chan, J W; Winhold, H; Corzett, M H; Ulloa, J M; Cosman, M; Balhorn, R; Huser, T

    2007-01-09

    Laser tweezers Raman spectroscopy (LTRS) is a novel, nondestructive, and label-free method that can be used to quantitatively measure changes in cellular activity in single living cells. Here, we demonstrate its use to monitor changes in a population of E. coli cells that occur during overexpression of a protein, the extracellular domain of myelin oligodendrocyte glycoprotein (MOG(1-120)) Raman spectra were acquired of individual E. coli cells suspended in solution and trapped by a single tightly focused laser beam. Overexpression of MOG(1-120) in transformed E. coli Rosetta-Gami (DE3)pLysS cells was induced by addition of isopropyl thiogalactoside (IPTG). Changes in the peak intensities of the Raman spectra from a population of cells were monitored and analyzed over a total duration of three hours. Data was also collected for concentrated purified MOG(1-120) protein in solution, and the spectra compared with that obtained for the MOG(1-120) expressing cells. Raman spectra of individual, living E. coli cells exhibit signatures due to DNA and protein molecular vibrations. Characteristic Raman markers associated with protein vibrations, such as 1257 cm{sup -1}, 1340 cm{sup -1}, 1453 cm{sup -1} and 1660 cm{sup -1}, are shown to increase as a function of time following the addition of IPTG. Comparison of these spectra and the spectra of purified MOG protein indicates that the changes are predominantly due to the induction of MOG protein expression. Protein expression was found to occur mostly within the second hour, with a 470% increase relative to the protein expressed in the first hour. A 230% relative increase between the second and third hour indicates that protein expression begins to level off within the third hour. It is demonstrated that LTRS has sufficient sensitivity for real-time, nondestructive, and quantitative monitoring of biological processes, such as protein expression, in single living cells. Such capabilities, which are not currently available in

  12. Au nanoparticle arrays produced by Pulsed Laser Deposition for Surface Enhanced Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Agarwal, N. R.; Neri, F.; Trusso, S.; Lucotti, A.; Ossi, P. M.

    2012-09-01

    Using UV pulses from KrF excimer laser, Au targets were ablated in varying pressures of argon to deposit Au nanoparticle (NP) arrays. The morphology of these films from island structures to isolated NPs, observed by SEM and TEM, depends on the gas pressure (10-100 Pa) and pulse number keeping other deposition parameters constant. By fast imaging of the plasma with an iCCD camera at different time delays with respect to the arrival of the laser pulse, we study the plasma propagation regime and we measured its initial velocity. These data and the measured average ablated mass per pulse were introduced to the mixed propagation model to calculate the average asymptotic size of clusters grown in the plume which were compared with NP sizes from TEM measurements. UV-visible Spectroscopy revealed changes of surface plasmon resonance with respect to NP size and spatial density and distribution on the surface. Suitable wavelength to excite the localized surface plasmon was chosen to detect ultra-low concentrations of Rhodamine and Apomorphine as an application to biomedical sensors, using Surface Enhanced Raman Spectroscopy (SERS). A comparison of SERS spectra taken under identical conditions from commercial substrates and from PLD substrates show that the latter have superior performances.

  13. The Detection of Biosignatures by Laser Raman Spectroscopy for Mars Exploration

    NASA Astrophysics Data System (ADS)

    Wei, J.; Wang, A.; Lu, Y.; Connor, K.; Bradley, A.; Marshall, C.; Steele, A.

    2014-06-01

    Laser Raman spectra of potential biosignature molecules on Mars possess strong bands to distinguish them from each other and from minerals. Tests of the detection limits demonstrated satisfaction of the requirements posted by Mars2020 STD report.

  14. Auger resonant Raman spectroscopy

    SciTech Connect

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

    1995-08-01

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

  15. Raman Spectroscopy of Cocrystals

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  16. Characterization of Air Plane Soot Surrogates using Raman spectroscopy and laser ablation techniques

    NASA Astrophysics Data System (ADS)

    Chazallon, Bertrand; Ortega, Ismael Kenneth; Ikhenazene, Raouf; Pirim, Claire; Carpentier, Yvain; Irimiea, Cornelia; Focsa, Cristian; Ouf, François-Xavier

    2016-04-01

    resulting spectra. If much literature discussed the most appropriate values of these parameters for analyzing graphite, coals, or amorphous carbon, only few works have dealt with soot, and no published studies have proposed the optimal parameter values for air-plane soot surrogates. In this work, we present the effect of three Raman parameters (laser wavelength, irradiance at sample, exposure time) on air-plane soot surrogates. The obtained results qualitatively indicate higher reactivity of soot samples collected in specific air-oxidation conditions. The surface chemical composition of the soot particles with special focus on PAHs are analyzed by two-Step (Desorption/Ionization) Laser Mass Spectrometry (L2MS) and Time of Fight Secondary Ion Mass Spectrometry (ToF-SIMS) techniques. In both techniques the spectra are obtained using positive polarity, which is better suited for detection of PAHs. A good agreement was obtained between the two techniques for the total PAH content of the analyzed samples. CAST samples are further processed by Raman spectroscopy to get complementary information on their structure. References [1] Lee et al., Atmos. Env. 44, 4678-4734, 2010 [2] IPCC 2014, Chap7: http://www.ipcc.ch [3] L. Dufour, Ciel et Terre, vol 82, p1-36, 1966 [4] C. Hoose & O. Möhler, Atmos.Chem.Phys. 12, 9817-9854, 2012 [5] Sadezky, A., Muckenhuber, H., Grothe, H., Niessner, R. and Pöschl U., (2005) Carbon, 43, 1731-1742. [6] Parent, Laffon, Marhaba, Ferry, Regier, Ortega, Chazallon, Carpentier, Focsa, (2016) Carbon (accepted)

  17. Compact Handheld Probe for Shifted Excitation Raman Difference Spectroscopy with Implemented Dual-Wavelength Diode Laser at 785 Nanometers.

    PubMed

    Maiwald, Martin; Eppich, Bernd; Ginolas, Arnim; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2015-10-01

    A compact handheld probe for shifted-excitation Raman difference spectroscopy (SERDS) with an implemented dual-wavelength diode laser with an emission at 785 nm is presented. The probe is milled from aluminum and has dimensions 100 × 28 × 12 mm. The diode laser provides two excitation lines with a spectral distance of 10 cm(-1) (0.62 nm), has a spectral width smaller than 11 pm, and reaches an optical power of 120 mW ex probe. Raman experiments were carried out using polystyrene (PS) as the test sample. During a measurement time of over 1 h, a stable spectral center position of the Raman line at 999 cm(-1) of PS was achieved within a spectral window of 0.1 cm(-1). Here, the Raman intensity of this line was observed with a peak-to-peak variation smaller than ±2%, dominated by shot noise interference. A deviation of the center position of a Raman line with <±1 cm(-1) was observed over the whole excitation power range. Raman investigations of the quartz glass window of the SERDS probe showed minor interference. The results demonstrate the suitability of the developed handheld probe for Raman investigations and the application of in situ SERDS experiments to fields such as food safety control, medical diagnostics, and process control. PMID:26449807

  18. 2 nm continuously tunable 488nm micro-integrated diode-laser-based SHG light source for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Braune, M.; Maiwald, M.; Sumpf, B.; Tränkle, G.

    2016-04-01

    Raman spectroscopy in the visible spectral range is of great interest due to resonant Raman effects. Nevertheless, fluorescence and ambient light can mask the weak Raman lines. Shifted excitation Raman difference spectroscopy is a demonstrated tool to overcome this drawback. To apply this method, a light source with two alternating wavelengths is necessary. The spectral distance between these two wavelengths has to be adapted to the width of the Raman signal. According to the sample under investigation the width of the Raman signal could be in the range of 3 cm-1 - 12 cm-1. In this work, a micro-integrated light source emitting at 488 nm with a continuous wavelength tuning range up to 2 nm (83 cm-1) is presented. The pump source, a DFB laser emitting at 976 nm, and a periodically poled lithium niobate (PPLN) ridge waveguide crystal is used for the second harmonic generation (SHG). Both components are mounted on a μ-Peltier-element for temperature control. Here, a common wavelength tuning of the pump wavelength and the acceptance bandwidth of the SHG crystal via temperature is achieved. With the results the light source is suitable for portable Raman and SERDS experiments with a flexible spectral distance between both excitation wavelengths for SERDS with respect to the sample under investigation.

  19. Fiber-coupled laser-induced breakdown and Raman spectroscopy for flexible sample characterization with depth profiling capabilities

    NASA Astrophysics Data System (ADS)

    Glaus, Reto; Hahn, David W.

    2014-10-01

    A combined laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy system for depth profile analyses is presented. The system incorporates a single 532 nm laser source, which is delivered through an optical fiber to the sample site. The homogenized laser beam results in well-defined cylindrical craters with diameters of 100 μm. LIBS depth profiling analyses of metals was performed applying pulse energies of about 1 mJ. The application of up to 500 pulses allowed to drill through layers of several tens of microns, while observing sharp transitions at the layer interfaces. The capability of the system for Raman spectroscopy was investigated for various polymer samples by reducing the pulse energies below the respective ablation threshold. A combined Raman/LIBS depth profiling was applied to a polymer-coated metal. Additionally, the capability of the system for calibration-free LIBS quantification (CF-LIBS) was evaluated. Quantification of major elements in metallic reference materials showed good agreement with the certified values with relative deviations of less than 30%. Finally, the optimized system was applied for depth profiling and elemental composition analysis of ancient Roman bronze rings. Overall, the presented setup combines the high flexibility of a fiber-coupled system with Raman and micro-LIBS, making the system interesting for depth profiling and elemental quantification in archaeometric as well as industrial applications.

  20. Remote Raman - Laser Induced Breakdown Spectroscopy (LIBS) Geochemical Investigation under Venus Atmospheric Conditions

    NASA Astrophysics Data System (ADS)

    Clegg, S. M.; Barefield, J. E.; Humphries, S.; Wiens, R. C.; Vaniman, D. T.; Sharma, S. K.; Misra, A. K.; Dyar, M. D.; Smrekar, S. E.

    2010-12-01

    The extreme Venus surface temperatures (~740 K) and atmospheric pressures (~93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical science goals without the risks associated with collecting samples and bringing them into the lander. Wiens et al. [1] and Sharma et al. [2] demonstrated that both analytical techniques can be integrated into a single instrument capable of planetary missions. The focus of this paper is to explore the capability to probe geologic samples with Raman - LIBS and demonstrate quantitative analysis under Venus surface conditions. Raman and LIBS are highly complementary analytical techniques capable of detecting both the mineralogical and geochemical composition of Venus surface materials. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from Soviet Venera and VEGA landers that collectively suggest a surface composition that is primarily tholeiitic basaltic [3] with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. These landers were not equipped to probe the surface mineralogy as can be accomplished with Raman spectroscopy. Based on the observed compositional differences and recognizing the imprecise nature of the existing data, 15 samples were chosen to constitute a Venus-analog suite for this study, including five basalts, two each of andesites, dacites, and sulfates, and single samples of a foidite, trachy-andesite, rhyolite, and basaltic trachyandesite under Venus conditions. LIBS data reduction involved generating a partial least squares (PLS) model with a subset of the rock powder standards to

  1. Identification of carotenoids in ancient salt from Death Valley, Saline Valley, and Searles Lake, California, using laser Raman spectroscopy.

    PubMed

    Winters, Y D; Lowenstein, T K; Timofeeff, M N

    2013-11-01

    Carotenoids are common components of many photosynthetic organisms and are well known from the red waters of hypersaline ecosystems where they are produced by halophilic algae and prokaryotes. They are also of great interest as biomarkers in extraterrestrial samples. Few laser Raman spectroscopy studies have examined ancient field samples, where pigments and microscopic life are less defined. Here, we have identified carotenoids in ancient halite brine inclusions, 9 ka to 1.44 Ma in age, from borehole cores taken from Death Valley, Saline Valley, and Searles Lake, California, for the first time with laser Raman spectroscopy. Carotenoids occurred in fluid inclusions as colorless to red-brown amorphous and crystalline masses associated with spheroidal algal cells similar in appearance to the common halophilic alga Dunaliella. Spectra from carotenoid standards, including β-carotene, lycopene, and lutein, were compared to microscopically targeted carotenoids in fluid inclusions. Carotenoids produced characteristic bands in the Raman spectrum, 1000-1020 cm⁻¹ (v₃), 1150-1170 cm⁻¹ (v₂), and 1500-1550 cm⁻¹ (v₁), when exposed to visible laser excitation. Laser Raman analyses confirmed the presence of carotenoids with these characteristic peaks in ancient halite. A number of band sets were repeated at various depths (ages), which suggests the stability of this class of organic molecules. Carotenoids appear well preserved in ancient salt, which supports other observations, for example, preserved DNA and live cells, that fluid inclusions in buried halite deposits preserve intact halophilic microbial ecosystems. This work demonstrates the value of laser Raman spectroscopy and carotenoids in extraterrestrial exploration for remnants of microbial life. PMID:24283928

  2. Classification and Discrimination of Minerals Using Laser Induced Breakdown Spectroscopy and Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Bi, Yunfeng; Zhang, Ying; Yan, Jingwen; Wu, Zhongchen; Li, Ying

    2015-11-01

    The classification and discrimination of minerals are important in geological research. The distribution of rocks and minerals may be inferred based on their identification, which is helpful for the investigation of some geological and environmental evolution problems, either on the earth or on other planets. LIBS and Raman spectra techniques have shown great advantages in simultaneous multi-component, in-situ, and non-destructive detection and they play an important role in rock composition analysis. In this presentation, six kinds of minerals (Gypsum, Spodumene, Barite, Haematite, Moonstone, and Labradorite) were detected by first using LIBS and Raman systems, and then several other methods (PCA, PLS-DA, ANN, and SVM) were used to evaluate the LIBS, Raman, and the fused LIBS/Raman data, respectively. The results indicate the superiority of the fused LIBS/Raman data in mineral classification, which stems from their complementary analysis abilities when studying element composition and structural features. supported by Shandong University of China (No. 2014ZQXM004) and National Natural Science Foundation of China (No. 41503063)

  3. Dual-wavelength Y-branch distributed Bragg reflector diode laser at 785 nanometers for shifted excitation Raman difference spectroscopy.

    PubMed

    Maiwald, Martin; Eppich, Bernd; Fricke, Jörg; Ginolas, Arnim; Bugge, Frank; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2014-01-01

    A dual-wavelength Y-branch distributed Bragg reflector (DBR) diode laser at 785 nm is presented as an excitation light source for shifted excitation Raman difference spectroscopy (SERDS). The monolithic device was realized with deeply etched surface DBR gratings using one-step epitaxy. An optical output power of 140 mW was obtained in continuous-wave (CW) operation for each laser cavity, with emission wavelengths of the device at 784.50 and 785.12 nm. A spectral width of the laser emission of 30 pm (0.5 cm(-1)), including 95% of optical power, was measured. The mean spectral distance of both excitation lines is 0.63 nm (10.2 cm(-1)) over the whole operating range. Raman experiments using polystyrene as the test sample and ambient light as the interference source were carried out and demonstrate the suitability of the dual-wavelength diode laser for SERDS. PMID:25061785

  4. Tunable sideband laser from cascaded four-wave mixing in thin glass for ultra-broadband femtosecond stimulated Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Liangdong; Liu, Weimin; Fang, Chong

    2013-08-01

    We demonstrate the generation of broadband up-converted multicolor array (BUMA) in a thin BK7 glass slide using two noncollinear weak near-IR laser pulses with various crossing angles. The BUMA signal arises from cubic nonlinear χ(3):χ(3) processes via cascaded four-wave mixing of the two incident beams. Broad and continuous tunability of BUMA is simply achieved by varying the time delay between the two pulses. We implement one of the BUMA sidebands as the probe pulse for femtosecond stimulated Raman spectroscopy and collect a solvent mixture anti-Stokes Raman spectrum with an ultrabroad detection range of ca. 100-4000 cm-1.

  5. Laser irradiation of carbon nanotube films: Effects and heat dissipation probed by Raman spectroscopy

    SciTech Connect

    Mialichi, J. R.; Brasil, M. J. S. P.; Iikawa, F.; Verissimo, C.; Moshkalev, S. A.

    2013-07-14

    We investigate the thermal properties of thin films formed by single- and multi-walled carbon nanotubes submitted to laser irradiation using Raman scattering as a probe of both the tube morphology and the local temperature. The nanotubes were submitted to heating/cooling cycles attaining high laser intensities ({approx}1.4 MW/cm{sup 2}) under vacuum and in the presence of an atmosphere, with and without oxygen. We investigate the heat diffusion of the irradiated nanotubes to their surroundings and the effect of laser annealing on their properties. The presence of oxygen during laser irradiation gives rise to an irreversible increase of the Raman efficiency of the carbon nanotubes and to a remarkable increase of the thermal conductivity of multi-walled films. The second effect can be applied to design thermal conductive channels in devices based on carbon nanotube films using laser beams.

  6. Raman spectroscopy of illicit substances

    NASA Astrophysics Data System (ADS)

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

    2007-10-01

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

  7. Evaluation of Residual Strain and Oxygen Vacancy in Multilayer Ceramic Capacitor Using Laser Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Nishida, Ken; Kishi, Hiroshi; Funakubo, Hiroshi; Takeuchi, Hironari; Katoda, Takashi; Yamamoto, Takashi

    2007-10-01

    Micro-Raman spectroscopy was employed to investigate the residual strain and oxygen vacancies of BaTiO3-based multilayer ceramic capacitors (MLCCs) with a Ni internal electrode. Strain was found to accumulate around the internal Ni electrodes layers than at other parts of the MLCCs. In addition, the number of oxygen vacancies near the internal Ni electrode was larger than that at any other parts of the MLCCs. These observations clearly show that Raman spectroscopy is extremely useful for evaluating the residual strain and oxygen vacancies in MLCC devices.

  8. Complementary analysis of tissue homogenates composition obtained by Vis and NIR laser excitations and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Staniszewska-Slezak, Emilia; Malek, Kamilla; Baranska, Malgorzata

    2015-08-01

    Raman spectroscopy and four excitation lines in the visible (Vis: 488, 532, 633 nm) and near infrared (NIR: 785 nm) were used for biochemical analysis of rat tissue homogenates, i.e. myocardium, brain, liver, lung, intestine, and kidney. The Vis Raman spectra are very similar for some organs (brain/intestines and kidney/liver) and dominated by heme signals when tissues of lung and myocardium were investigated (especially with 532 nm excitation). On the other hand, the NIR Raman spectra are specific for each tissue and more informative than the corresponding ones collected with the Vis excitations. The spectra analyzed without any special pre-processing clearly illustrate different chemical composition of each tissue and give information about main components e.g. lipids or proteins, but also about the content of some specific compounds such as amino acid residues, nucleotides and nucleobases. However, in order to obtain the whole spectral information about tissues complex composition the spectra of Vis and NIR excitations should be collected and analyzed together. A good agreement of data gathered from Raman spectra of the homogenates and those obtained previously from Raman imaging of the tissue cross-sections indicates that the presented here approach can be a method of choice for an investigation of biochemical variation in animal tissues. Moreover, the Raman spectral profile of tissue homogenates is specific enough to be used for an investigation of potential pathological changes the organism undergoes, in particular when supported by the complementary FTIR spectroscopy.

  9. Raman spectroscopy of transition metal dichalcogenides

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  10. Raman spectroscopy of transition metal dichalcogenides.

    PubMed

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

    2016-09-01

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

  11. Laser-induced blood serum fluorescence and Raman spectroscopy for cancer diagnosis

    NASA Astrophysics Data System (ADS)

    Li, Xiaozhou; Wang, Qiuyu; Lin, Junxiu

    1999-09-01

    Laser induced auto-fluorescence and Raman spectra of serum from cancerous and normal people are measured and analyzed. The content of (beta) -carotene in the serum from normal man is higher than that from the cancerous one, this result agrees with other reports.

  12. Raman spectroscopy of composites

    SciTech Connect

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

    1994-12-31

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

  13. Raman spectroscopy in astrobiology.

    PubMed

    Jorge Villar, Susana E; Edwards, Howell G M

    2006-01-01

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

  14. Fiber enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  15. Detection of explosives and latent fingerprint residues utilizing laser pointer-based Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Malka, Itamar; Petrushansky, Alona; Rosenwaks, Salman; Bar, Ilana

    2013-12-01

    A modular, compact Raman spectrometer, based on a green laser pointer, an air cooled intensified charged coupled device and a x, y motorized translation stage was developed and applied for point detection. Its performance was tested for measurements of Raman spectra of liquids, trace amounts of explosives and individual particles, as well as for locating individual particles of interest and for chemical imaging of residues of latent human fingerprints. This system was found to be highly sensitive, identifying masses as low as ~1 ng in short times. The point and real-time detection capabilities of the spectrometer, together with the portability that it offers, make it a potential candidate for replacing existing Raman microscopes and for field applications.

  16. Wavelength Selection For Laser Raman Spectroscopy of Putative Martian Habitats and Biomolecules

    NASA Astrophysics Data System (ADS)

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

    Pigments are key potential biomarkers for any former life on Mars because of the selective pressure of solar radiation on any biological system that could have evolved at its surface. We have found that the near -Infrared laser Raman spectrometer available to use was eminently suitable for diagnostic analysis of pigments because of their minimal autofluorescence at its 1064 nm excitation wav elength. However, we have now evaluated a diverse range of excitation wavelengths to confirm this choice, to ensure that we have the best technique to seek for pigments and their derivatives from any former surface life on Mars. The Raman is weak relative to fluorescence, which results in elevated baseline and concurrent swamping of Raman bands. We confirm the molecular information available from near-IR FT Raman spectra for two highly pigmented UV-tolerant epilithic Antarctic lichens (Acarospora chlorop hana and Caloplaca saxicola) from Victoria Land, a whole endolithic microbial community and endolithic cyanobacterium Chroococcidiopsis from within translucent sandstone of the Trans -Antarctic Mountains, and the free- living cyanobacterium Nostoc commune from Alexander Island, Antarctic Peninsula region. We also show that much of the information we require on biomolecules is not evident from lasers of shorter wavelengths. A miniature 1064 nm Raman spectrometer with an In-Ga-As detector sensitive to IR is being developed by Montana State University (now existing as a prototype) as the prime instrument for a proposed UK-led Mars rover mission (Vanguard). Preliminary spectra from this system confirm the suitability of the near-IR laser.

  17. Portable Raman spectroscopy using retina-safe (1550 nm) laser excitation

    NASA Astrophysics Data System (ADS)

    Brouillette, Carl; Smith, Wayne; Donahue, Michael; Huang, Hermes; Shende, Chetan; Sengupta, Atanu; Inscore, Frank; Patient, Michael; Farquharson, Stuart

    2012-06-01

    The use of portable Raman analyzers to identify unknown substances in the field has grown dramatically during the past decade. Measurements often require the laser beam to exit the confines of the sample compartment, which increases the potential of eye or skin damage. This is especially true for most commercial analyzers, which use 785 nm laser excitation. To overcome this safety concern, we have built a portable FT-Raman analyzer using a 1550 nm retina-safe excitation laser. Excitation at 1550 nm falls within the 1400 to 2000 nm retina-safe range, so called because the least amount of damage to the eye occurs in this spectral region. In contrast to wavelengths below 1400 nm, the retina-safe wavelengths are not focused by the eye, but are absorbed by the cornea, aqueous and vitreous humor. Here we compare the performance of this system to measurements of explosives at shorter wavelengths, as well as its ability to measure surface-enhanced Raman spectra of several chemicals, including the food contaminant melamine.

  18. Laser Spectroscopy

    NASA Astrophysics Data System (ADS)

    Katori, H.; Yoneda, H.; Nakagawa, K.; Shimizu, F.

    2010-02-01

    Anderson localization of matter-waves in a controlled disorder: a quantum simulator? / A. Aspect ... [et al.] -- Squeezing and entanglement in a Bose-Einstein condensate / C. Gross ... [et al.] -- New physics in dipolar Bose-Einstein condensates / Y. Kawaguchi, H. Saito, and M. Ueda -- Observation of vacuum fluctuations in a spinor Bose-Einstein condensate / C. Klempt ... [et al.] -- Negative-index media for matter waves / F. Perales ... [et al.] -- Entanglement of two individual atoms using the Rydberg blockade / A. Browaeys ... [et al.] -- Array of mesoscopic ensembles on a magnetic atom chip / A. F. Tauschinsky ... [et al.] -- Stability of the proton-to-electron mass ratio tested with molecules using an optical link to primary clock / A. Amy-Klein ... [et al.] -- Metastable helium: lifetime measurements using cold atoms as a test of QED / K. G. H. Baldwin ... [et al.] -- Optical lattice clocks with single occupancy bosons and spin-polarized fermions toward 10[symbol] accuracy / M. Takamoto ... [et al.] -- Frequency measurements of Al[symbol] and Hg[symbol] optical standards / W. M. Itano ... [et al.] -- Switching of light with light using cold atoms inside a hollow optical fiber / M. Bajcsy ... [et al.] -- Room-temperature atomic ensembles for quantum memory and magnetometry / K. Jensen ... [et al.] -- Components for multi-photon non-classical state preparation and measurement / G. Puentes ... [et al.] -- Quantum field state measurement and reconstruction in a cavity by quantum nondemolition photon counting / M. Brune ... [et al.] -- XUV frequency comb spectroscopy / C. Gohle ... [et al.] -- Ultrahigh-repetition-rate pulse train with absolute-phase control produced by an adiabatic raman process / M. Katsuragawa ... [et al.] -- Strongly correlated bosons and fermions in optical lattices / S. Will ... [et al.] -- Bragg spectroscopy of ultracold bose gases in optical lattices / L. Fallani ... [et al.] -- Synthetic quantum many-body systems / C. Guerlin ... [et al

  19. Aperture combined Raman laser

    SciTech Connect

    Woods, C.; Tang, K.; Howton, C.; Muller, D.; Hunter, R.O. Jr.

    1983-01-01

    Excimer lasers, while able to produce large powers and energies, are limited to a few discrete wavelengths. Efficient Raman shifting promises the availability of a much broader wavelength range. A method was developed which both Raman shifts and allows for multiple pump beams.

  20. Automated head-space analysis for quality assurance of pharmaceutical vials by laser Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gilbert, A. S.; Hobbs, K. W.; Reeves, A. H.; Jobson, P. P.

    1994-11-01

    We have constructed a fully automated Raman spectroscopic headspace gas analyzer for the assaying of oxygen and nitrogen in sealed vials. A single grating spectrograph with pre-filter and multichannel detection is utilized. Visible radiation at 488 nanometers is obtained from an argon ion laser. It is used to inspect vials containing a pharmaceutical product which is freeze dried and sealed under nitrogen (N2). This product, though buffered, is sensitive to carbon dioxide (CO2); therefore the analyzer is utilized to reject vials which have suffered ingress of air by detecting the presence of oxygen (O2).

  1. Unveiling the identity of distant targets through advanced Raman-laser-induced breakdown spectroscopy data fusion strategies.

    PubMed

    Moros, Javier; Laserna, J Javier

    2015-03-01

    Data fusion is the process of combining data gathered from two or more sensors to produce a more specific, comprehensive and unified dataset of the inspected target. On this basis, much has been said about the possible benefits resulting from the use of molecular and atomic information for the detection of explosives. The orthogonal nature of the spectral and compositional information provided by Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) makes them suitable candidates for an optimal combination of their data, thus achieving inferences that are not feasible using a single sensor. The present manuscript evaluates several architectures for the combination of spectral outputs from these two sensors in order to compare the benefits and drawbacks of data fusion for improving the overall identification performance. From the simple assembling (concatenation or addition) of Raman and LIBS spectra to signals' processing on the basis of linear algebra (either the outer product or the outer sum), different identification patterns of several compounds (explosives, potential confusants and supports) have been built. The efficiency on target differentiation by using each of the architectures has been evaluated by comparing the identification yield obtained for all the inspected targets from correlation and similarity measurements. Additionally, a specific code integrated by several of these patterns to identify each compound has also been evaluated. This approach permits to obtain a better knowledge about the identity of an interrogated target, mainly in those decisive cases in which LIBS or Raman cannot be effective separately to reach a decision. PMID:25618716

  2. Analysis of experimental tendinitis in rats treated with laser and platelet-rich plasma therapies by Raman spectroscopy and histometry.

    PubMed

    de Carvalho, Paula Kariluce; Silveira, Landulfo; Barbosa, Danillo; Munin, Egberto; Salgado, Miguel Angel Castillo; Villaverde, Antonio Balbin

    2016-01-01

    The objective of this controlled experimental study was to analyze the changes in the Achilles tendons of rats with experimentally induced tendinitis after treatment with platelet-rich plasma (PRP) and/or laser therapies by histometry to quantify fibroblasts and by Raman spectroscopy to determine the biochemical concentration of collagen types I and III. Fifty-four male Wistar rats were divided into six treatment groups: control (G1); PRP only (G2); irradiation with 660 nm laser (G3); irradiation with 830 nm laser (G4); PRP plus 660 nm laser irradiation (G5); and PRP plus 830 nm laser irradiation (G6). Injuries (partial tenotomy) were inflicted in the middle third of the Achilles tendon, with PRP added prior to suture in the appropriate experimental groups. A diode laser (model Laser Flash® III, DMC Equipamentos Ltda, São Carlos, SP, Brazil) that can be operated in two wavelengths 660 and 830 nm was used for irradiation treatments. The irradiation protocol was energy density of 70 J/cm², 20 s irradiation time, and 0.028 cm² spot area, per point in three points in the injured. The histometry was made in micrographical images of the H&E stained sections and evaluated by ImageJ (version 1.46r)®. Raman spectra were collected using a dispersive spectrometer at 830 nm excitation, 200 mW power, and 10 s integration time (P-1 Raman system, Lambda Solutions, Inc. MA, USA). The relative amount of type I collagen was significantly greater in the PRP plus 830 nm laser irradiation group (468 ± 188) than in the control (147 ± 137), 630 nm laser only (191 ± 117), and 830 nm laser only (196 ± 106) groups (p < 0.01), while the quantity of type III collagen was significantly greater in the PRP-only group compared to both irradiated groups without PRP (p < 0.05). Treatment with PRP combined with irradiation at 830 nm resulted in a larger number of fibroblasts and increased concentration of type I collagen, thus accelerating the healing of the injured

  3. Emerging Dental Applications of Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

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

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

  4. Diagnostics of a capillary discharge of a CO2 waveguide laser by coherent anti-Stokes Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Vakhterov, A. A.; Iliukhin, A. A.; Konev, Iu. B.; Lipatov, N. I.; Pashinin, P. P.

    1985-01-01

    Experimental results are reported from coherent anti-Stokes Raman spectroscopy (CARS) diagnostic studies of capillary discharge in the CO2:N2:He = 1:1:8 working mixture of a CO2 waveguide laser. The CARS scans were used to characterize the translational temperature of the gas and the vibrational temperatures of the discharge plasma components. The data are vital for identifying anharmonic states which reduce the laser power and working mixture lifetime. Data are furnished on the translational temperature and vibrational temperature as functions of the capillary radius. CARS is concluded to be a valid technique for studying the distribution of pump power among the degrees of freedom of the working mixture components, even when dissociation is occurring.

  5. Laser induced fluorescence and Raman spectroscopy in capillary electrophoresis as an possible instrument for extraterrestrial life signs detection.

    NASA Astrophysics Data System (ADS)

    Mikhail, Gorlenko; Cheptcov, Vladimir; Anton, Maydykovskiy; Eugeniy, Vasilev

    The one of a significant aims in extraterrestrial exploration is a seeking for a life traces in a open space and planetary objects. Complex composition and unknown origin of suspected signs of life required у new analytical approaches and technical solutions. The promising assai here can be Laser induced fluorescence and Raman spectroscopy methods. The combined instrument developed by our team reveal the advantage of capillary electrophoresis assays in a junction with laser induced fluorescence detection technology. We optimized excitation configuration of fluorescence in capillary electrophoresis to reduce pumping laser power up to 1 mW and decrease background scattering. The improvement of the device sensitivity at poor sample concentration we achieved by incorporating fluorescence flow-through cuvette into spectrometer. That allows to simplify setup, to minimize weight and increase reproducibility of measurements. The device has been tasted in complex organic chemical mixes and microbial strains differentiation tasks. 3d multinational spectra allow us to increase the spectra information loads in comparison with ordinary capillary electrophoresis approaches. Possible updating the device with Raman approach can even furthermore multiple the differentiation power of the instrument. The analytical module developed using this approach can be potentially effectively used in extraterrestrial researches as a payload of the future spacecraft.

  6. Micro-mirror arrays for Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Duncan, W. M.

    2015-03-01

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

  7. Raman spectroscopy and laser desorption mass spectrometry for minimal destructive forensic analysis of black and color inkjet printed documents.

    PubMed

    Heudt, Laetitia; Debois, Delphine; Zimmerman, Tyler A; Köhler, Laurent; Bano, Fouzia; Partouche, Franck; Duwez, Anne-Sophie; Gilbert, Bernard; De Pauw, Edwin

    2012-06-10

    Inkjet ink analysis is the best way to discriminate between printed documents, or even though more difficult, to connect an inkjet printed document with a brand or model of printers. Raman spectroscopy and laser desorption mass spectrometry (LDMS) have been demonstrated as powerful tools for dyes and pigments analysis, which are ink components. The aim of this work is to evaluate the aforementioned techniques for inkjet inks analysis in terms of discriminating power, information quality, and nondestructive capability. So, we investigated 10 different inkjet ink cartridges (primary colors and black), 7 from the HP manufacturer and one each from Epson, Canon and Lexmark. This paper demonstrates the capabilities of three methods: Raman spectroscopy, LDMS and MALDI-MS. Raman spectroscopy, as it is preferable to try the nondestructive approach first, is successfully adapted to the analysis of color printed documents in most cases. For analysis of color inkjet inks by LDMS, we show that a MALDI matrix (9-aminoacridine, 9AA) is needed to desorb and to ionize dyes from most inkjet inks (except Epson inks). Therefore, a method was developed to apply the 9AA MALDI matrix directly onto the piece of paper while avoiding analyte spreading. The obtained mass spectra are very discriminating and lead to information about ink additives and paper compositions. Discrimination of black inkjet printed documents is more difficult because of the common use of carbon black as the principal pigment. We show for the first time the possibility to discriminate between two black-printed documents coming from different, as well as from the same, manufacturers. Mass spectra recorded from black inks in positive ion mode LDMS detect polyethylene glycol polymers which have characteristic mass distributions and end groups. Moreover, software has been developed for rapid and objective comparison of the low mass range of these positive mode LDMS spectra which have characteristic unknown peaks. PMID

  8. Difference Raman spectroscopy of DNA molecules

    NASA Astrophysics Data System (ADS)

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

    2015-01-01

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

  9. Femtosecond Stimulated Raman Spectroscopy.

    PubMed

    Dietze, Daniel R; Mathies, Richard A

    2016-05-01

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

  10. Developing Continuous-Wave Raman Lasers Using Solid Para-Hydrogen and Barium Nitrate for Molecular Spectroscopy Applications

    NASA Astrophysics Data System (ADS)

    Evans, William R.; Momose, Takamasa; McCall, Benjamin J.

    2012-06-01

    Many interesting molecular targets have vibrational transitions between 5 and 10 μm. However, widely tunable continuous-wave laser sources in this region are extremely rare. One possible solution to this situation is with continuous-wave Raman lasers. We will present our recent work toward the construction of two continuous-wave Raman lasers: one using solid para-hydrogen as the Raman shifting medium, and the other using barium nitrate. Solid para-hydrogen is a promising medium for a continuous-wave Raman laser because of its high Raman gain coefficient (18 cm/MW, almost 400 times higher than any room-temperature crystal), wide spectral transmission window (transparent from ˜100 nm to ˜30 μm), its nature as a ``quantum crystal," and its large Raman shift (4150 cm-1 in the solid). We will also describe our more recent work designing and constructing a continuous-wave Raman laser in barium nitrate. Barium nitrate has the advantage of being the room-temperature crystal with the highest Raman gain coefficient, as well as being highly transparent from 350 to 1800 nm. Barium nitrate has been used as a continuous-wave Raman shifter for several years. Our recent work builds upon this foundation, combining lessons learned from our work with solid para-hydrogen. Our design is the first barium nitrate Raman laser using an actively-locked, doubly-resonant laser cavity. This holds the promise of requiring much lower threshold pump powers than previous setups. We will discuss some of the details in designing and building these lasers. Finally, we will report on the current state of our projects as well as anticipated future work.

  11. Effect of Low-Level Laser Therapy in an Experimental Model of Osteoarthritis in Rats Evaluated Through Raman Spectroscopy

    PubMed Central

    Mangueira, Nilton Maciel; Xavier, Murilo; de Souza, Renato Aparecido; Salgado, Miguel Angel Castillo; Silveira, Landulfo

    2015-01-01

    Abstract Objective: This work aimed to investigate the biochemical changes associated with low-level laser therapy (LLLT) using 660 and 780 nm, on a well-established experimental model of osteoarthritis (OA) in the knees of rats with induced collagenase, using histomorphometry and Raman spectroscopy. Materials and methods: Thirty-six Wistar rats were divided into four groups: control (GCON, n=9), collagenase without treatment (GCOL, n=9), collagenase with LLLT 660 nm treatment (G660, n=8), and collagenase with LLLT 780 nm treatment (G780, n=10). LLLT protocol was: 30 mW power output, 10 sec irradiation time, 0.04 cm2 spot size, 0.3 J energy, 0.75 W/cm2 irradiance, and 7.5 J/cm2 fluence per session per day, during 14 days. Then, knees were withdrawn and submitted to histomorphometry and Raman spectroscopy analysis. Principal components analysis (PCA) and Mahalanobis distance were employed to characterize the spectral findings. Results: Histomorphometry revealed a significant increase in the amount of collagen III for the group irradiated with 660 nm. The Raman bands at 1247, 1273, and 1453 cm−1 (from principal component score PC2), attributed to collagen type II, and 1460 cm−1 (from PC3), attributed to collagen type III, suggested that the LLLT causes acceleration in cellular activity, especially on the cells that repair cartilage, accelerating the breakdown of cartilage destroyed by collagenase and stimulating the fibroblast to synthesize repairing collagen III. Conclusions: LLLT accelerated the initial breakdown of cartilage destroyed by collagenase and stimulated the fibroblast to synthesize the repairing collagen III, suggesting a beneficial effect of LLLT on OA. PMID:25714387

  12. Applications of high resolution inverse Raman spectroscopy

    SciTech Connect

    Owyoung, A.; Esherick, P.

    1980-01-01

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

  13. Online fluorescence suppression in modulated Raman spectroscopy.

    PubMed

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

    2010-01-15

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

  14. Communication: two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): simultaneous planar imaging and multiplex spectroscopy in a single laser shot.

    PubMed

    Bohlin, Alexis; Kliewer, Christopher J

    2013-06-14

    Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15,000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm(2). PMID:23781772

  15. Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot

    NASA Astrophysics Data System (ADS)

    Bohlin, Alexis; Kliewer, Christopher J.

    2013-06-01

    Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15 000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm2.

  16. Communication: Two-dimensional gas-phase coherent anti-Stokes Raman spectroscopy (2D-CARS): Simultaneous planar imaging and multiplex spectroscopy in a single laser shot

    SciTech Connect

    Bohlin, Alexis; Kliewer, Christopher J.

    2013-01-01

    Coherent anti-Stokes Raman spectroscopy (CARS) has been widely used as a powerful tool for chemical sensing, molecular dynamics measurements, and rovibrational spectroscopy since its development over 30 years ago, finding use in fields of study as diverse as combustion diagnostics, cell biology, plasma physics, and the standoff detection of explosives. The capability for acquiring resolved CARS spectra in multiple spatial dimensions within a single laser shot has been a long-standing goal for the study of dynamical processes, but has proven elusive because of both phase-matching and detection considerations. Here, by combining new phase matching and detection schemes with the high efficiency of femtosecond excitation of Raman coherences, we introduce a technique for single-shot two-dimensional (2D) spatial measurements of gas phase CARS spectra. We demonstrate a spectrometer enabling both 2D plane imaging and spectroscopy simultaneously, and present the instantaneous measurement of 15, 000 spatially correlated rotational CARS spectra in N2 and air over a 2D field of 40 mm2.

  17. SEM and Raman spectroscopy analyses of laser-induced periodic surface structures grown by ethanol-assisted femtosecond laser ablation of chromium

    NASA Astrophysics Data System (ADS)

    Bashir, Shazia; Shahid Rafique, M.; Nathala, Chandra S. R.; Ajami, Ali; Husinsky, Wolfgang

    2015-05-01

    The effect of fluence and pulse duration on the growth of nanostructures on chromium (Cr) surfaces has been investigated upon irradiation of femtosecond (fs) laser pulses in a liquid confined environment of ethanol. In order to explore the effect of fluence, targets were exposed to 1000 pulses at various peak fluences ranging from 4.7 to 11.8 J cm-2 for pulse duration of ∼25 fs. In order to explore the effect of pulse duration, targets were exposed to fs laser pulses of various pulse durations ranging from 25 to 100 fs, for a constant fluence of 11.8 J cm-2. Surface morphology and structural transformations have been analyzed by scanning electron microscopy and Raman spectroscopy, respectively. After laser irradiation, disordered sputtered surface with intense melting and cracking is obtained at the central ablated areas, which are augmented with increasing laser fluence due to enhanced thermal effects. At the peripheral ablated areas, where local fluence is approximately in the range of 1.4-4 mJ cm-2, very well-defined laser-induced periodic surface structures (LIPSS) with periodicity ranging from 270 to 370 nm along with dot-like structures are formed. As far as the pulse duration is concerned, a significant effect on the surface modification of Cr has been revealed. In the central ablated areas, for the shortest pulse duration (25 fs), only melting has been observed. However, LIPSS with dot-like structures and droplets have been grown for longer pulse durations. The periodicity of LIPSS increases and density of dot-like structures decreases with increasing pulse duration. The chemical and structural modifications of irradiated Cr have been revealed by Raman spectroscopy. It confirms the formation of new bands of chromium oxides and enol complexes or Cr-carbonyl compounds. The peak intensities of identified bands are dependent upon laser fluence and pulse duration.

  18. Analysis of natural and artificial ultramarine blue pigments using laser induced breakdown and pulsed Raman spectroscopy, statistical analysis and light microscopy.

    PubMed

    Osticioli, I; Mendes, N F C; Nevin, A; Gil, Francisco P S C; Becucci, M; Castellucci, E

    2009-08-01

    Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532 nm for the analysis of five commercially available pigments collectively known as "ultramarine blue", a sodium silicate material of either mineral origin or an artificially produced glass. LIBS and Raman spectroscopy have provided information regarding the elemental and molecular composition of the samples; additionally, an analytical protocol for the differentiation between natural (lapis lazuli) and artificial ultramarine blue pigments is proposed. In particular LIBS analysis has allowed the discrimination between pigments on the basis of peaks ascribed to calcium. The presence of calcite in the natural blue pigments has been confirmed following Raman spectroscopy in specific areas of the samples, and micro-Raman and optical microscopy have further corroborated the presence of calcite inclusions in the samples of natural origin. Finally multivariate analysis of Laser induced breakdown spectra using principal component analysis (PCA) further enhanced the differentiation between natural and artificial ultramarine blue pigments. PMID:19129003

  19. Analysis of natural and artificial ultramarine blue pigments using laser induced breakdown and pulsed Raman spectroscopy, statistical analysis and light microscopy

    NASA Astrophysics Data System (ADS)

    Osticioli, I.; Mendes, N. F. C.; Nevin, A.; Gil, Francisco P. S. C.; Becucci, M.; Castellucci, E.

    2009-08-01

    Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532 nm for the analysis of five commercially available pigments collectively known as "ultramarine blue", a sodium silicate material of either mineral origin or an artificially produced glass. LIBS and Raman spectroscopy have provided information regarding the elemental and molecular composition of the samples; additionally, an analytical protocol for the differentiation between natural (lapis lazuli) and artificial ultramarine blue pigments is proposed. In particular LIBS analysis has allowed the discrimination between pigments on the basis of peaks ascribed to calcium. The presence of calcite in the natural blue pigments has been confirmed following Raman spectroscopy in specific areas of the samples, and micro-Raman and optical microscopy have further corroborated the presence of calcite inclusions in the samples of natural origin. Finally multivariate analysis of Laser induced breakdown spectra using principal component analysis (PCA) further enhanced the differentiation between natural and artificial ultramarine blue pigments.

  20. Raman spectroscopy of white wines.

    PubMed

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

    2015-08-15

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  2. Disposable sheath that facilitates endoscopic Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

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

  3. Raman and Laser-Induced Breakdown Spectroscopy (LIBS) Remote Geochemical Analysis Under Venus Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Clegg, S.; Sharma, S. K.; Misra, A. K.; Dyar, M. D.; Dallmann, N.; Wiens, R. C.; Vaniman, D. T.; Speicher, E. A.; Smrekar, S. E.; Wang, A.; Maurice, S.; Esposito, L.

    2012-03-01

    A remote Raman-LIBS spectrometer (RLS) is a rapid method to determine Venus surface chemistry and mineralogy without collecting samples and bringing them into the lander. The RLS results from 18 synthetic samples will be presented.

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

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

  5. Raman spectroscopy in halophile research.

    PubMed

    Jehlička, Jan; Oren, Aharon

    2013-01-01

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

  6. Raman spectroscopy in halophile research

    PubMed Central

    Jehlička, Jan; Oren, Aharon

    2013-01-01

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

  7. Characterization of Kevlar Using Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

    2007-01-01

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

  8. Proximal Analysis of Regolith Habitats and Protective Biomolecules in Situ by Laser Raman Spectroscopy: Overview of Terrestrial Antarctic Habitats and Mars Analogs

    NASA Astrophysics Data System (ADS)

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

    2000-04-01

    Fourier-transform laser Raman spectroscopy in the near infrared (1064 nm) has been used to characterize a variety of key pigments and biomolecules produced by cyanobacteria and other stresstolerant microbes in material from extreme Antarctic cold deserts analogous to martian habitats. These compounds include photosynthetic pigments and sunscreens to protect against harmful UV radiation in the light zone (chlorophyll, scytonemin, β-carotene) and photoprotective minerals, such as silica containing iron (III) oxide. Calcium oxalate mono- and dihydrate produced as a result of the biological weathering processes and stress-protective compounds, necessary to protect organisms against desiccation, freezing temperatures, and hypersalinity, such as water-replacement molecules (trehalose), are also monitored. From the results obtained using Antarctic samples, it is shown that a laser-based system can be used to characterize biomolecules in their natural state within their mineral microhabitats. Because of the similarities between the Antarctic cold desert ecosystems, which represent some of the most extreme terrestrial environmental habitats, and putative martian analogs, the laser-Raman spectrosocopic approach is proposed for the detection of former life on Mars analogs to terrestrial cyanobacteria under stress, such as stromatolites, evaporites, and endolithic communities. To this end, the spectral database that is being accumulated from laser-Raman studies of these Antarctic communities will provide a resource of potential biomarkers for future remote laser-Raman analysis on future Mars missions.

  9. A virtual experiment control and data acquisition system for in situ laser heated diamond anvil cell Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Subramanian, N.; Struzhkin, Viktor V.; Goncharov, Alexander F.; Hemley, Russell J.

    2010-09-01

    Doubled-sided laser heated diamond anvil cell methods allow simultaneous in situ confocal Raman measurements of materials up to megabar pressures and high temperatures. This paper describes a virtual control and data acquisition system developed to automate setups for simultaneous Raman/laser heating experiments. The system enables reduction of experiment time by ˜90% in comparison to manual operations, allowing measurements of high quality Raman spectra of even highly reactive or diffusive samples, such as hydrogen at extreme conditions using continuous wave laser heating. These types of measurements are very difficult and often impossible to obtain in a manual operation mode. Complete data archiving and accurate control of various experimental parameters (e.g., on-the-fly temperature determination and self-adjusting data collection time to avoid signal saturation) can be done, and open up possibilities of other types of experiments involving extreme conditions.

  10. Raman spectroscopy of shocked water

    SciTech Connect

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

    1983-07-01

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

  11. High fidelity nanohole enhanced Raman spectroscopy.

    SciTech Connect

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

    2009-01-01

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

  12. Determining the Authenticity of Gemstones Using Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

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

    1998-04-01

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

  13. Raman Spectroscopy of Microbial Pigments

    PubMed Central

    Edwards, Howell G. M.; Oren, Aharon

    2014-01-01

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

  14. Femtosecond pulse laser notch shaping via fiber Bragg grating for the excitation source on the coherent anti-Stokes Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Oh, Seung Ryeol; Kwon, Won Sik; Kim, Jin Hwan; Kim, Kyung-Soo; Kim, Soohyun

    2015-03-01

    Single-pulse coherently controlled nonlinear Raman spectroscopy is the simplest method among the coherent anti-Stokes Raman spectroscopy systems. In recent research, it has been proven that notch-shaped femtosecond pulse laser can be used to collect the coherent anti-Stokes Raman signals. In this study, we applied a fiber Bragg grating to the notch filtering component on the femtosecond pulse lasers. The experiment was performed incorporating a titanium sapphire femtosecond pulse laser source with a 100 mm length of 780-HP fiber which is inscribed 30 mm of Bragg grating. The fiber Bragg grating has 785 nm Bragg wavelength with 0.9 nm bandwidth. We proved that if the pulse lasers have above a certain level of positive group delay dispersion, it is sufficient to propagate in the fiber Bragg grating without any spectral distortion. After passing through the fiber Bragg grating, the pulse laser is reflected on the chirped mirror for 40 times to make the transform-limited pulse. Finally, the pulse time duration was 37 fs, average power was 50mW, and showed an adequate notch shape. Furthermore, the simulation of third order polarization signal is performed using MATLAB tools and the simulation result shows that spectral characteristic and time duration of the pulse is sufficient to use as an excitation source for single-pulse coherent anti-Stokes Raman spectroscopy. In conclusion, the proposed method is more simple and cost-effective than the methods of previous research which use grating pairs and resonant photonic crystal slab.

  15. Nano-structured surfaces by laser interference lithography and fs-laser direct writing as substrates for surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ben Mohammadi, L.; Hundertmark, N.; Kullmann, F.; Fleissner, F.; Klotzbücher, T.

    2012-03-01

    Nano-structured surfaces were generated by laser interference lithography and femtosecond-laser direct writing of photo resists that subsequently were metallized by electroless plating or sputter deposition of silver. Laser lithography was performed with a 405 nm coherent diode laser in AZ9260, using two-beam interference with double illumination by 90° rotating of the substrate, leading to 2D periodic surface patterns with smallest features of the order of 200 nm. With fs-laser direct writing using a Ti-sapphire oscillator of 800 nm and 15 fs pulse length, feature sizes down to 100 nm were realized in SU8, even with aspect ratios much larger than 1. Metallization with electroless plating delivered either grainy silver coatings with a grain size around 100 nm or needle-like silver coatings with a needle length around 100 nm and a width of around 10 nm. The metallized substrates were exposed to aqueous solutions of Rhodamine 6G (Rh6G) of different concentrations and the corresponding Raman signals were recorded with a Raman micro-probe spectrometer. The nano-structured surfaces lead to formation of Raman bands attributable to Rh6G. In case of the grainy silver coatings, surfaces without nano-structures did not show Raman activity, indicating that grating-coupled surface plasmons play the dominant role for Raman enhancement. In case of substrates coated with the needle-shaped silver crystallites, Raman activity was also seen in regions without laser-generated nano-structures, indicating that localized particle plasmons play the dominant role for Raman enhancement. A comparison with Raman spectra measured with conventional Raman spectrometer showed that the enhancement factor achieved by the laser-generated nano-structures themself, is of the order of 6×104. Raman intensity as a function of Rh6G concentration revealed a regular behaviour, as expected from a Langmuir isotherm.

  16. Healing and evaluating guinea pig skin incision after surgical suture and laser tissue by welding using in vivo Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Alimova, A.; Sriramoju, V.; Chakraverty, R.; Muthukattil, R.; Alfano, R. R.

    2010-02-01

    Changes in collagen in the wound during the healing process of guinea pig skin following surgical incisions and LTW was evaluated using in vivo, using Raman spectroscopy. Raman spectroscopy provided information regarding the internal structure of the proteins. After the incisions were closed either by suturing or by LTW the ratio of the Raman peaks of the amide III (1247 cm-1) band to a peak at 1326 cm-1 used to evaluate the progression of collagen deposition. Histopathology was used as the gold standard. LTW skin demonstrated better healing than sutured skin, exhibiting minimal hyperkeratosis, minimal collagen deposition, near-normal surface contour, and minimal loss of dermal appendages. This work is important to plastic surgery.

  17. Raman Spectroscopy of Amorphous Carbon

    SciTech Connect

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

    1998-01-01

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

  18. Surface-Enhanced Raman Spectroscopy.

    ERIC Educational Resources Information Center

    Garrell, Robin L.

    1989-01-01

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

  19. Study of the reaction products of SF6 and C in the laser heated diamond anvil cell by pair distribution function analysis and micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Rademacher, N.; Bayarjargal, L.; Morgenroth, W.; Bauer, J. D.; Milman, V.; Winkler, B.

    2015-05-01

    The decomposition of SF6 in the presence of glassy carbon was induced in laser heated diamond anvil cells at 10-11 GPa and 2000-2500 K. The reaction products were characterised by synchrotron X-ray diffraction, including high pressure pair distribution function analysis, and micro-Raman spectroscopy combined with atomistic model calculations. The decomposition leads to elemental amorphous helical sulfur and crystalline CF4-III. Two different sulfur phases, namely helical Sμ and crystalline α-S8, were observed after recovering the laser heated samples of different experiments at ambient conditions.

  20. Raman spectroscopy of Alzheimer's diseased tissue

    NASA Astrophysics Data System (ADS)

    Sudworth, Caroline D.; Krasner, Neville

    2004-07-01

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

  1. Design and Calibration of a Raman Spectrometer for use in a Laser Spectroscopy Instrument Intended to Analyze Martian Surface and Atmospheric Characteristics for NASA

    NASA Technical Reports Server (NTRS)

    Lucas, John F.; Hornef, James

    2016-01-01

    This project's goal is the design of a Raman spectroscopy instrument to be utilized by NASA in an integrated spectroscopy strategy that will include Laser-Induced Breakdown Spectroscopy (LIBS) and Laser-Induced Florescence Spectroscopy (LIFS) for molecule and element identification on Mars Europa, and various asteroids. The instrument is to be down scaled from a dedicated rover mounted instrument into a compact unit with the same capabilities and accuracy as the larger instrument. The focus for this design is a spectrometer that utilizes Raman spectroscopy. The spectrometer has a calculated range of 218 nm wavelength spectrum with a resolution of 1.23 nm. To filter out the laser source wavelength of 532 nm the spectrometer design utilizes a 532 nm wavelength dichroic mirror and a 532 nm wavelength notch filter. The remaining scatter signal is concentrated by a 20 x microscopic objective through a 25-micron vertical slit into a 5mm diameter, 1cm focal length double concave focusing lens. The light is then diffracted by a 1600 Lines per Millimeter (L/mm) dual holographic transmission grating. This spectrum signal is captured by a 1-inch diameter double convex 3 cm focal length capture lens. An Intensified Charge Couple Device (ICCD) is placed within the initial focal cone of the capture lens and the Raman signal captured is to be analyzed through spectroscopy imaging software. This combination allows for accurate Raman spectroscopy to be achieved. The components for the spectrometer have been bench tested in a series of prototype developments based on theoretical calculations, alignment, and scaling strategies. The mounting platform is 2.5 cm wide by 8.8 cm long by 7 cm height. This platform has been tested and calibrated with various sources such as a neon light source and ruby crystal. This platform is intended to be enclosed in a ruggedized enclosure for mounting on a rover platform. The size and functionality of the Raman spectrometer allows for the rover to

  2. Remote adjustable focus Raman spectroscopy probe

    DOEpatents

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

    1999-01-01

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

  3. Surface Enhanced Raman Spectroscopy of Volatile Organic molecules on the surface of Zinc Nanoparticles Produced by Laser Ablation

    NASA Astrophysics Data System (ADS)

    Singh, Subhash C.; Swarnkar, Raj K.; Ankit, Preyas; Chattopadhyaya, Mahesh C.; Gopal, R.

    2008-11-01

    Surface enhanced Raman spectroscopy have provided potential tool for the detection of organic/biological molecules within the cell of living organism. This technique is suitable for in vivo as well as in vitro detection upto single molecular level. In the present work we have studied SERS activity of zinc nanoparticles on CCl4 and CHCl3 molecules. Colloidal solution of zinc nanoparticles was found as a suitable substrate for Raman signal enhancement. The applied technique may be useful for the sensing of organic/biological molecules as a trace in solid as well as in liquid media.

  4. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1990-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

  5. Heterodyne laser spectroscopy system

    DOEpatents

    Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

    1989-01-01

    A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  7. Raman spectroscopy under extreme conditions

    SciTech Connect

    Goncharov, A F; Crowhurst, J C

    2004-11-05

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

  8. Simultaneous Conoscopic Holography and Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

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

  9. Near shot-noise limited hyperspectral stimulated Raman scattering spectroscopy using low energy lasers and a fast CMOS array.

    PubMed

    Rock, William; Bonn, Mischa; Parekh, Sapun H

    2013-07-01

    We demonstrate near shot-noise limited hyperspectral stimulated Raman scattering (SRS) spectroscopy using oscillator-only excitation conditions. Using a fast CMOS camera synchronized to an acousto-optic modulator and subtracting subsequent frames acquired at up to 1 MHz frame rates, we demonstrate demodulation and recovery of the SRS spectrum. Surprisingly, we observe that the signal-to-noise of SRS spectra is invariant at modulation frequencies down to 2.5 kHz. Our approach allows for a direct comparison of SRS with coherent anti-Stokes Raman scattering (CARS) spectroscopy under identical experimental conditions. Our findings suggest that hyperspectral SRS imaging with shot-noise limited performance at biologically compatible excitation energies is feasible after minor modifications to fast frame-rate CMOS array technology. PMID:23842298

  10. Raman spectroscopy of bone metastasis

    NASA Astrophysics Data System (ADS)

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

    2012-02-01

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

  11. 5,000 h reliable operation of 785nm dual-wavelength DBR-RW diode lasers suitable for Raman spectroscopy and SERDS

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Müller, André; Maiwald, Martin

    2016-03-01

    Monolithic wavelength stabilized diode lasers, e.g. distributed Bragg reflector (DBR) ridge waveguide (RW) lasers, are well-suited light sources for compact and portable Raman spectroscopic systems. In the case of in situ and outdoor investigations, the weak Raman lines are often superimposed by daylight, artificial light sources or fluorescence signals from the samples under study. Among others, shifted excitation Raman difference spectroscopy (SERDS) has been demonstrated as a powerful and easy-to-use technique to separate the Raman lines from disturbing background signals. SERDS is based on subsequential excitation of the sample with two slightly shifted wavelengths. The Raman lines follow the change in the excitation wavelength whereas the non-Raman signals remain unchanged. For SERDS dual-wavelength light sources, e.g., mini-arrays containing two DBR-RW lasers, are requested. Moreover, for portable Raman instruments such as handheld devices robust and reliable excitation light sources with lifetimes > 1,000 h are preferred. In this work, reliability investigations of dual-wavelength DBR-RW mini-arrays over a total test time of 5,000 h are presented. Wavelength stabilization and narrowing of the spectral emission is realized by 10th-order DBR surface gratings defined by i-line wafer stepper technology. The DBR-section has a length of 500 μm, the devices a total length of 3 mm. The ridge waveguide has a stripe width of 2.2 μm. Maximum output powers up to 215 mW per emitter were measured. Over the whole power range, 95 % of the emitted power is within a spectral width of 0.15 nm (2.5 cm-1), which is smaller than the spectral width needed to resolve most Raman lines of solid and liquid samples. In a step-stress test, the devices were tested at 50 mW, followed by 75 mW and finally at 100 mW per emitter. Electro-optical and spectral measurements were performed before, during and after the test. All emitters under study did not show any deterioration of their

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

    ERIC Educational Resources Information Center

    Chase, Bruce

    2007-01-01

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

  13. Comparison of two concepts for dual-wavelength DBR ridge waveguide diode lasers at 785 nm suitable for shifted excitation Raman difference spectroscopy

    NASA Astrophysics Data System (ADS)

    Sumpf, Bernd; Maiwald, Martin; Müller, André; Fricke, Jörg; Ressel, Peter; Bugge, Frank; Erbert, Götz; Tränkle, Günther

    2015-08-01

    Two concepts of dual-wavelength 785-nm DBR ridge waveguide (RW) lasers, i.e. RW mini-arrays consisting of two DBR-RW lasers and Y-branch DBR-RW lasers, will be compared with respect to their usability as excitation light sources for shifted excitation Raman difference spectroscopy (SERDS). For both types of devices for each wavelength, output powers up to 215 mW were measured. A stable spectral distance between the laser emissions of the two resonator branches with the targeted value of 0.6 nm, i.e. 10 cm-1, is observed. In the case of the mini-array up to an output power of about 70 mW, the device shows single-mode operation. Although at higher power levels, mode hops and multi-mode operation occur, the emission width smaller than 0.15 nm still meets the requirements for Raman measurements of solids and liquids. Over the whole working range, the spectral distance between the two wavelengths is approximately constant with 0.62 nm. The near field shows two emission spots according to the dimension of the RW and their processed distance of 20 µm. The Y-branch laser shows single-mode operation up to 150 mW with a narrow spectral emission width. At higher powers also, multi-mode operation with an emission width of 0.15 nm occurs. The nearly diffraction-limited emission comes from one output aperture; the far-field emission shows a pronounced asymmetry between the two branches. Both types of devices fulfil the spectral requirements from Raman spectroscopy and SERDS up to 215 mW output power.

  14. Raman spectroscopy for analysis of thorium compounds

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  15. Raman spectroscopy of ion-implanted silicon

    SciTech Connect

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

    1997-11-01

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

  16. Laser wavelength selection for Raman spectroscopy of microbial pigments in situ in Antarctic desert ecosystem analogues of former habitats on Mars

    NASA Astrophysics Data System (ADS)

    Edwards, Howell G. M.; Newton, Emma M.; Wynn-Williams, David D.; Dickensheets, David; Schoen, Chris; Crowder, Chelle

    2002-10-01

    The vital ultraviolet- (UV-) protective and photosynthetic pigments of cyanobacteria and lichens (microbial symbioses) that dominate primary production in Antarctic desert ecosystems auto-fluoresce at short wavelengths. We therefore use a long-wavelength (1064 nm) infrared laser for non-intrusive in situ Raman spectrometry of their ecologically significant compounds (especially pigments). To confirm that the power loss at this longer wavelength is justified to avoid swamping by background fluorescence, we compared Raman spectra obtained with excitation at 1064, 852, 830, 785, 633 and 515 nm. These are typical of lasers used for Raman spectroscopy. We analysed communities of the cyanobacterium Nostoc commune and the highly pigmented lichens Acarospora chlorophana and Caloplaca saxicola. These require screening compounds (e.g. pigments such as scytonemin in cyanobacteria and rhizocarpic acid in the fungal symbiont of lichens). They are augmented by quenching pigments (e.g. carotenoids) to dissipate the energy of free radicals generated by penetrating UV. We also analysed organisms having avoidance strategies (e.g. endolithic communities within translucent rocks, including the common cyanobacterium Chroococcidiopsis). These require accessory pigments for photosynthesis at very low light intensities. Although some organisms gave useable Raman spectra with short-wavelength lasers, 1064 nm was the only excitation that was consistently excellent for all organisms. We conclude that a 1064 nm Raman spectrometer, miniaturized using an InGaAs detector, is the optimal instrument for in situ studies of pigmented microbial communities at the limits of life on Earth. This has practical potential for the quest for biomolecules residual from any former surface life on Mars.

  17. Transcutaneous Raman Spectroscopy of Bone

    NASA Astrophysics Data System (ADS)

    Maher, Jason R.

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

  18. Detection of carbon-fluorine bonds in organofluorine compounds by Raman spectroscopy using a copper-vapor laser

    NASA Astrophysics Data System (ADS)

    Sharts, Clay M.; Gorelik, Vladimir S.; Agoltsov, A. M.; Zlobina, Ludmila I.; Sharts, Olga N.

    1999-02-01

    The Raman spectra of fluoro-organic compounds show specific emission bands for carbon-fluorine bonds in the range 500- 800 wave numbers (cm-1)). With very limited exceptions, biological materials do not contain carbon- fluorine bonds. Fluoro-organic compounds introduced into biological samples can be detected by a Raman emission signal. Normal mode C-F bond bands are observed: (1) at 710- 785 cm -1 for trifluoromethyl groups; (2) at 530-610 cm -1 for aromatic organofluorine bonds; (3) a range centered at 690 cm -1 for difluoromethylene groups. Specific examples of normal mode C-F bond emissions for organofluorine compounds containing trifluoromethyl groups are: 1-bromoperfluorooctane, 726 cm -1; perfluorodecanoic acid, 730 cm -1; triperfluoropropylamine, 750 cm -1; 1,3,5-tris- (trifluoromethyl)-benzene, 730 cm -1; Fluoxetine (Prozac) commercial powdered pill at 782 cm -1. Compounds containing aromatic C-F bonds are: hexafluorobenzene, 569 cm MIN1; pentafluoropyridine, 589 cm -1. Difluoromethylene groups: perfluorodecalin, 692 cm-1; perfluorocyclohexane, 691 cm -1. Raman spectra were observed with a standard single monochromator. The 510.8 nm light source was a copper-vapor laser operated at 3-10 watts with 10-12 nanosecond pulses at 10 kHz repetition rate. Detection was made with a time-gated photomultiplier tube. Resonance Raman spectra were also observed at 255.4 nm, using a frequency doubling crystal. Observed spectra were free of fluorescence with very sharp strong C-F lines.

  19. Time-resolved detection of aromatic compounds on planetary surfaces by ultraviolet laser induced fluorescence and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Eshelman, E.; Daly, M. G.; Slater, G.; Cloutis, E.

    2015-12-01

    Raman spectroscopic instruments are highly capable in the search for organics on Mars due to the potential to perform rapid and nondestructive measurements on unprepared samples. Upcoming and future Raman instruments are likely to also incorporate laser-induced fluorescence (LIF) capabilities, which can be added for modest cost and complexity. We demonstrate that it is possible to obtain sub-ns fluorescence lifetime measurements of Mars-relevant organics and minerals if a fast time-gating capability is used with an intensified detector and a short ultraviolet laser pulse. This serves a primary purpose of discriminating mineral from short-lived (less than 10 ns) organic fluorescence, considered a potential biosignature. Additionally, lifetime measurements may assist in determining if more than one fluorescing species is present and provide information concerning the molecular structure as well as the local environment. Fast time-gating is also useful at longer visible or near-IR wavelengths, as this approach increases the sensitivity of the instrument to organic material by removing the majority of the fluorescence background from the Raman signal and reducing the effect of ambient light.

  20. Raman Spectroscopy of Ocular Tissue

    NASA Astrophysics Data System (ADS)

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

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

  1. Raman and Photoluminescence Spectroscopy in Mineral Identification

    NASA Astrophysics Data System (ADS)

    Kuehn, J. W.

    2014-06-01

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

  2. Raman spectroscopies in shock-compressed materials

    SciTech Connect

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

    1983-01-01

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

  3. Surface-enhanced Raman spectroscopy of pterins

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-03-01

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

  5. Raman spectroscopy for diagnosis of glioblastoma multiforme

    NASA Astrophysics Data System (ADS)

    Clary, Candace Elise

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

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

    NASA Technical Reports Server (NTRS)

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

    2007-01-01

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

  7. Laser Spectroscopy and Frequency Combs

    NASA Astrophysics Data System (ADS)

    Hänsch, Theodor W.; Picqué, Nathalie

    2013-12-01

    The spectrum of a frequency comb, commonly generated by a mode-locked femtosecond laser consists of several hundred thousand precisely evenly spaced spectral lines. Such laser frequency combs have revolutionized the art measuring the frequency of light, and they provide the long-missing clockwork for optical atomic clocks. The invention of the frequency comb technique has been motivated by precision laser spectroscopy of the simple hydrogen atom. The availability of commercial instruments is facilitating the evolution of new applications far beyond the original purpose. Laser combs are becoming powerful instruments for broadband molecular spectroscopy by dramatically improving the resolution and recording speed of Fourier spectrometers and by creating new opportunities for highly multiplexed nonlinear spectroscopy, such as two-photon spectroscopy or coherent Raman spectroscopy. Other emerging applications of frequency combs range from fundamental research in astronomy, chemistry, or attosecond science to telecommunications and satellite navigation.

  8. Ultrasensitive coherent Raman technique with picosecond lasers

    SciTech Connect

    Schauer, M.W.; Pellin, M.J.; Biwer, B.M.; Gruen, D.M.

    1987-02-16

    The use of picosecond, Q-switched lasers and advanced polarization schemes has led to the development of a coherent Raman technique with the sensitivity of coherent anti-Stokes Raman spectroscopy experiments but without the troublesome phase-matching requirements. Experiments in dilute solutions of benzene indicate a limit of sensitivity for the current apparatus of 2.5 x 10/sup -4/ M in two minutes of signal averaging over 150 cm/sup -1/. Possible applications to the in situ study of passive films and thin films on transparent media are discussed.

  9. Raman accumulator as a fusion laser driver

    DOEpatents

    George, E. Victor; Swingle, James C.

    1985-01-01

    Apparatus for simultaneous laser pulse amplification and compression, using multiple pass Raman scattering in one Raman cell and pulse switchout from the optical cavity through use of a dichroic device associated with the Raman cell.

  10. Raman accumulator as a fusion laser driver

    DOEpatents

    George, E.V.; Swingle, J.C.

    1982-03-31

    Apparatus for simultaneous laser pulse amplification and compression, using multiple pass Raman scattering in one Raman cell and pulse switchout from the optical cavity through use of a dichroic device associated with the Raman cell.

  11. Anti-Stokes Raman laser

    SciTech Connect

    White, J.C.; Henderson, D.

    1982-02-01

    The first observation of nonresonant, stimulated anti-Stokes Raman emission is reported. A metastable T1 (6rho /sup 2/P/sup 0//sub 3/2/) inversion is created by selective photodissociation of TlCl. Raman scattering from the Tl metastable state to ground using 532- and 355-nm pump lasers resulted in stimulated emission at 376 and 278 nm, respectively. Conversion efficiencies up to 10% are reported.

  12. Low-temperature Raman spectroscopy of copper and silver nanoparticles ion-synthesized in a silica glass and subjected to laser annealing

    NASA Astrophysics Data System (ADS)

    Kurbatova, N. V.; Galyautdinov, M. F.; Shtyrkov, E. I.; Nuzhdin, V. I.; Stepanov, A. L.

    2010-06-01

    The modification of the shape of ion-synthesized silver and copper nanoparticles in a silica glass during laser annealing has been studied for the first time by Raman spectroscopy at a temperature of 77 K. The laser annealing has been carried out for a wavelength of 694 nm at the edge of the plasmon absorption spectrum of nanoparticles. A comparison of the experimental spectra and the calculated modes of in-phase bending vibrations of the “harmonica” type in nanostrings of the corresponding metals has demonstrated their good agreement. The effects observed have been discussed from the standpoint of the size quantization of vibrations in metal nanowires. This methodical approach has made it possible to estimate the sizes of the Ag and Cu nanoparticles under the assumption that they have an elongated form; in this case, their average lengths are equal to 2.5 and 1.4 nm, respectively.

  13. Raman Spectroscopy and Related Techniques in Biomedicine

    PubMed Central

    Downes, Andrew; Elfick, Alistair

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  15. High Pressure in situ Micro-Raman Spectroscopy of Ge-Sn System Synthesized in a Laser Heated Diamond Anvil Cell

    NASA Astrophysics Data System (ADS)

    Sorb, Y. A.; Subramanian, N.; Ravindran, T. R.; Sahu, P. Ch.

    2011-07-01

    GexSn1-x has been predicted to be a direct band-gap semiconductor, but attempts to synthesize this in bulk form by conventional synthesis methods have not been successful on account of the poor solubility of Sn in Ge. In this work, laser heated diamond anvil cell (LHDAC) technique has been employed to explore formation of bulk GexSn1-x (x = 0.7) at varying pressures and temperatures. At ˜8 GPa, in situ micro-Raman spectroscopy done on several regions of temperature quenched samples laser heated up to ˜2000 K reveals vanishing of the intense Ge TO(Γ) phonon at ˜326 cm-1 and appearance of a softer mode, concurrent with appearance of a new high intensity Raman mode at ˜660 cm-1. These indicate dilation of the Ge-Ge bond by virtue of significant miscibility of βSn at these high P-T conditions and hints at formation of new stiff Ge-Sn bonds.

  16. Applications of Raman spectroscopy in life science

    NASA Astrophysics Data System (ADS)

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

    2015-06-01

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

  17. In vivo Raman spectroscopy of cervix cancers

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. Deep ultraviolet diamond Raman laser.

    PubMed

    Granados, Eduardo; Spence, David J; Mildren, Richard P

    2011-05-23

    We present a synchronously pumped diamond Raman laser operating at 275.7 nm pumped by the 4th harmonic of a mode locked Nd:YVO4 laser. The laser had a threshold pump pulse energy of 5.8 nJ and generated up to 0.96 nJ pulses at 10.3% conversion efficiency. The results agree well with a numerical model that includes two-photon absorption of the pump and Stokes beams and uses a Raman gain coefficient of diamond of 100 cm/GW. We also report on the observation of nanometer scale two-photon assisted etching of the diamond crystal surfaces. PMID:21643343

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

    PubMed

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

    2006-01-01

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

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

    PubMed Central

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

    2006-01-01

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

  1. Time-encoded Raman scattering (TICO-Raman) with Fourier domain mode locked (FDML) lasers

    NASA Astrophysics Data System (ADS)

    Karpf, Sebastian; Eibl, Matthias; Wieser, Wolfgang; Klein, Thomas; Huber, Robert

    2015-07-01

    We present a new concept for performing stimulated Raman spectroscopy and microscopy by employing rapidly wavelength swept Fourier Domain Mode locked (FDML) lasers [1]. FDML lasers are known for fastest imaging in swept-source optical coherence tomography [2, 3]. We employ this continuous and repetitive wavelength sweep to generate broadband, high resolution stimulated Raman spectra with a new, time-encoded (TICO) concept [4]. This allows for encoding and detecting the stimulated Raman gain on the FDML laser intensity directly in time. Therefore we use actively modulated pump lasers, which are electronically synchronized to the FDML laser, in combination with a fast analog-to-digital converter (ADC) at 1.8 GSamples/s. We present hyperspectral Raman images with color-coded, molecular contrast.

  2. Investigation of the chemical stability of the laser-induced fluorescence tracers acetone, diethylketone, and toluene under IC engine conditions using Raman spectroscopy.

    PubMed

    Trost, Johannes; Zigan, Lars; Eichmann, Simone C; Seeger, Thomas; Leipertz, Alfred

    2013-09-01

    This paper reports on an investigation of the chemical stability of the common laser-induced fluorescence (LIF) tracers acetone, diethylketone, and toluene. Stability is analyzed using linear Raman spectroscopy inside a heated pressure cell with optical access, which is used for the LIF calibration of these tracers. The measurements examine the influence of temperature, pressure, and residence time on tracer oxidation, which occurs without a rise in temperature or pressure inside the cell, highlighting the need for optical detection. A comparison between the three different tracers shows large differences, with diethylketone having the lowest and toluene by far the highest stability. An analysis of the sensitivity of the measurement shows that the detection limit of the oxidized tracer is well below 3% molar fraction, which is typical for LIF applications in combustion devices such as internal combustion (IC) engines. Furthermore, the effect on the LIF signal intensity is examined in an isothermal turbulent mixing study. PMID:24085091

  3. Molecular velocimetry using stimulated Raman spectroscopy

    NASA Technical Reports Server (NTRS)

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

    1984-01-01

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

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

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

    PubMed

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

    2016-08-01

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

  6. Study of virus by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

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

  7. Inverse Raman bands in ultrafast Raman loss spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2011-10-01

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

  8. Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods

    PubMed Central

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

    2005-01-01

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

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

    DOE PAGESBeta

    Villa-Aleman, Eliel; Wellons, Matthew S.

    2016-03-22

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

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

    DOE PAGESBeta

    Villa-Aleman, Eliel; Wellons, Matthew S.

    2016-03-22

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

  11. Occlusal caries detection using polarized Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ionita, I.; Bulou, A.

    2008-02-01

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

  12. Raman spectroscopy and polarization: Selected case studies

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  13. Applications of Raman spectroscopy to gemology.

    PubMed

    Bersani, Danilo; Lottici, Pier Paolo

    2010-08-01

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

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

    SciTech Connect

    Meyer, Matthew W.

    2013-01-01

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

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

    PubMed

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

    2010-07-01

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

  16. Raman spectroscopy at the tritium laboratory Karlsruhe

    SciTech Connect

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

    2015-03-15

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

  17. Mobile Raman spectroscopy in astrobiology research.

    PubMed

    Vandenabeele, Peter; Jehlička, Jan

    2014-12-13

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

  18. Nondestructive evaluation of internal maturity of tomatoes using spatially offset Raman spectroscopy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This research explored the use of spatially offset Raman spectroscopy (SORS) for nondestructive evaluation of internal maturity of tomatoes. A Raman spectroscopy system using a 785 nm laser was developed to collect spatially-offset spectra in the wavenumber range of 200 – 2500. The SORS measuremen...

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Chung, Jin Hyuk; Cho, Soo Gyeong

    2013-06-01

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

  1. Potential of Raman and Infrared Spectroscopy for Plant Analysis

    NASA Astrophysics Data System (ADS)

    Schulz, H.

    2008-11-01

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

  2. Raman spectroscopy characterization of actinide oxides (U 1-yPu y)O 2: Resistance to oxidation by the laser beam and examination of defects

    NASA Astrophysics Data System (ADS)

    Jégou, C.; Caraballo, R.; Peuget, S.; Roudil, D.; Desgranges, L.; Magnin, M.

    2010-10-01

    Structural changes in four (U 1-yPu y)O 2 materials with very different plutonium concentrations (0 ⩽ y ⩽ 1) and damage levels (up to 110 dpa) were studied by Raman spectroscopy. The novel experimental approach developed for this purpose consisted in using a laser beam as a heat source to assess the reactivity and structural changes of these materials according to the power supplied locally by the laser. The experiments were carried out in air and in water with or without hydrogen peroxide. As expected, the material response to oxidation in air depends on the plutonium content of the test oxide. At the highest power levels U 3O 8 generally forms with UO 2 whereas no significant change in the spectra indicating oxidation is observed for samples with high plutonium content ( 239PuO 2). Samples containing 25 wt.% plutonium exhibit intermediate behavior, typified mainly by a higher-intensity 632 cm -1 peak and the disappearance of the 1LO peak at 575 cm -1. This can be attributed to the presence of anion sublattice defects without any formation of higher oxides. The range of materials examined also allowed us to distinguish partly the chemical effects of alpha self-irradiation. The results obtained with water and hydrogen peroxide (a water radiolysis product) on a severely damaged 238PuO 2 specimen highlight a specific behavior, observed for the first time.

  3. Using Raman spectroscopy to characterize biological materials.

    PubMed

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

    2016-04-01

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

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

    PubMed

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

    2014-09-01

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

  5. Airborne chemistry coupled to Raman spectroscopy.

    PubMed

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

    2003-05-01

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

  6. Multiplex coherent raman spectroscopy detector and method

    NASA Technical Reports Server (NTRS)

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

    2004-01-01

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

  7. Multiplex coherent raman spectroscopy detector and method

    DOEpatents

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

    2004-06-08

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

  8. Imaging EGFR distribution using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  9. Cone penetrometer fiber optic raman spectroscopy probe assembly

    DOEpatents

    Kyle, Kevin R.; Brown, Steven B.

    2000-01-01

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

  10. Cone penetrometer fiber optic Raman spectroscopy probe assembly

    SciTech Connect

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

    2000-01-25

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

  11. Raman and surface-enhanced Raman spectroscopy evidence for oxidation-induced decomposition of graphite

    NASA Astrophysics Data System (ADS)

    Owens, Frank J.

    2015-06-01

    It has been proposed that reduction of exfoliated graphite oxide could be a potential method for producing large quantities of graphene. Raman and surface-enhanced Raman spectroscopy are used to show that oxidation of graphite and exfoliated graphite significantly increases the defect structure of both materials. This would likely lead to a heavily defected graphene structure when oxygen is removed. To insure the observed decomposition is not due to the laser light, the effect of laser intensity on the materials was investigated. It was found that at the highest laser intensity (1.4 × 108 W/M2) there was a significant increase in defects. However, lower laser intensity was found which did not produce defects and was used in the studies of the effect of oxidation on the spectra.

  12. Identification of gemstone treatments with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2000-09-01

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

  13. Pulsed-ultraviolet laser Raman diagnostics of plasma processing discharges

    SciTech Connect

    Hargis P.J. Jr.; Greenberg, K.E.

    1988-11-07

    Spontaneous Raman spectroscopy with pulsed-ultraviolet laser excitation of the Stokes vibrational Raman lines was used to measure the percent dissociation of nitrogen and sulfur hexafluoride in low-pressure radio refrequency discharges of the type used for processing semiconductor materials. Measurements of the percent dissociation of sulfur hexafluoride, at pressures between 200 and 600 mTorr, show a strong pressure dependence which is consistent with recombination playing an important role in sulfur hexafluoride discharge kinetics.

  14. Analysis of lipsticks using Raman spectroscopy.

    PubMed

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

    2013-10-10

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

  15. Raman and multichannel Raman spectroscopy of biological systems

    NASA Astrophysics Data System (ADS)

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

    1991-05-01

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

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

    SciTech Connect

    Yoshida, Kyohei; Hachiya, Kan; Okumura, Kensuke; Mishima, Kenta; Inukai, Motoharu; Torgasin, Konstantin; Omer, Mohamed; Sonobe, Taro; Zen, Heishun; Negm, Hani; Kii, Toshiteru; Masuda, Kai; Ohgaki, Hideaki

    2013-10-28

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

  17. Raman spectroscopy of gliomas: an exploratory study

    NASA Astrophysics Data System (ADS)

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

    2014-03-01

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

  18. Challenges Analyzing Gypsum on Mars by Raman Spectroscopy.

    PubMed

    Marshall, Craig P; Olcott Marshall, Alison

    2015-09-01

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

  19. Two-frequency fibre Raman laser

    SciTech Connect

    Paramonov, Vladimir M; Kurkov, Andrei S; Medvedkov, O I; Grukh, Dmitrii A; Dianov, Evgenii M

    2004-03-31

    A new scheme of a fibre Raman laser emitting at two wavelengths is proposed. The scheme uses a one-stage Raman converter with the output Bragg grating with the reflectivity above 99%. Lasing at two wavelengths is achieved due to the overlap of the output emission spectrum with the reflection spectrum of the output Bragg grating. (lasers)

  20. Coherent Raman spectroscopy for supersonic flow measurments

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1986-01-01

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

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

    PubMed

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

    2009-05-01

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

  2. Analytical procedure for characterization of medieval wall-paintings by X-ray fluorescence spectrometry, laser ablation inductively coupled plasma mass spectrometry and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Syta, Olga; Rozum, Karol; Choińska, Marta; Zielińska, Dobrochna; Żukowska, Grażyna Zofia; Kijowska, Agnieszka; Wagner, Barbara

    2014-11-01

    Analytical procedure for the comprehensive chemical characterization of samples from medieval Nubian wall-paintings by means of portable X-ray fluorescence (pXRF), laser ablation inductively coupled plasma mass spectrometry (LA-ICPMS) and Raman spectroscopy (RS) was proposed in this work. The procedure was used for elemental and molecular investigations of samples from archeological excavations in Nubia (modern southern Egypt and northern Sudan). Numerous remains of churches with painted decorations dated back to the 7th-14th century were excavated in the region of medieval kingdoms of Nubia but many aspects of this art and its technology are still unknown. Samples from the selected archeological sites (Faras, Old Dongola and Banganarti) were analyzed in the form of transfers (n = 26), small fragments collected during the excavations (n = 35) and cross sections (n = 15). XRF was used to collect data about elemental composition, LA-ICPMS allowed mapping of selected elements, while RS was used to get the molecular information about the samples. The preliminary results indicated the usefulness of the proposed analytical procedure for distinguishing the substances, from both the surface and sub-surface domains of the wall-paintings. The possibility to identify raw materials from the wall-paintings will be used in the further systematic, archeometric studies devoted to the detailed comparison of various historic Nubian centers.

  3. Theory of femtosecond stimulated Raman spectroscopy.

    PubMed

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

    2004-08-22

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

  4. Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

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

    2001-01-01

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

  5. Raman spectroscopy investigation of magnetite nanoparticles in ferrofluids

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  6. Raman gain of SiC as a potential medium for Raman lasers

    NASA Astrophysics Data System (ADS)

    Merkle, Larry D.; Zhang, Jun; Allen, Graham; Dawson, Jay W.; Dubinskii, Mark

    2015-03-01

    We have investigated stimulated Raman scattering in the 4H polytype of SiC, due to its excellent thermal conductivity which is of great importance for power scaling of Raman lasers. Spectroscopy verifies the sample's polytype and precludes any significant admixture of other polytypes. Tests indicate the moderate optical quality of this commercially available sample. Using pump-probe measurements around 1030 nm, we find the Raman gain coefficient of the major peak at 777 cm-1 to be 0.46 cm/GW. Although this value is only modest, calculations and experience with other Raman materials indicate that Raman lasing of 4H SiC should be possible with reasonable intensities of 1064-nm pulsed pumping.

  7. Micro-Raman spectroscopy on oral tissues

    NASA Astrophysics Data System (ADS)

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

    2006-02-01

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

  8. Raman Spectroscopy Cell-based Biosensors

    PubMed Central

    Notingher, Ioan

    2007-01-01

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

  9. Raman Spectroscopy of Bone and Cartilage

    NASA Astrophysics Data System (ADS)

    Morris, Michael

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

  10. Raman spectroscopy of shocked water

    SciTech Connect

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

    1985-08-01

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

  11. Coherent Raman dual-comb spectroscopy and imaging

    NASA Astrophysics Data System (ADS)

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

    2014-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

  15. Bladder cancer diagnosis during cystoscopy using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-08-01

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

  17. Molecular dynamics of glycine ions in alanine doped TGS single crystal as probed by polarized laser raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Bajpai, P. K.; Verma, A. L.

    2012-10-01

    Polarized Raman spectra of pure and alanine doped tri-glycine sulfate (TGS) single crystals at 12 K in different scattering geometries are analyzed. Sub species modes due to three crystallographically distinguishable glycine ions G (I), G (II) and G (III) are assigned. It is observed that alanine doping does not change the crystalline field and acts as local perturbation only. The major changes due to doping are observed in the relative intensities of different modes; most of the modes associated with G (I) and SO42- ions show reversal behavior in relative intensity at high doping concentration. The observed spectral changes are analyzed in terms of reorientation of G (I) ions with sub species modes of G (II)/ G (III) following the reorientation due to complex hydrogen bonding network.

  18. Optical Coherence Tomography and Raman Spectroscopy of the retina

    SciTech Connect

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

    2009-01-16

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

  19. FT-Raman spectroscopy study of human breast tissue

    NASA Astrophysics Data System (ADS)

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

    2004-07-01

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

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

    PubMed

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

    2013-10-17

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

  1. Raman spectroscopy of 'Bisphenol A'

    NASA Astrophysics Data System (ADS)

    Ullah, Ramzan; Zheng, Yuxiang

    2016-03-01

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

  2. Raman spectroscopy in head and neck cancer

    PubMed Central

    2010-01-01

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

  3. Tissue measurement using 1064 nm dispersive Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  5. Assessment of bone healing on tibial fractures treated with wire osteosynthesis associated or not with infrared laser light and biphasic ceramic bone graft (HATCP) and guided bone regeneration (GBR): Raman spectroscopy study

    NASA Astrophysics Data System (ADS)

    Bastos de Carvalho, Fabíola; Aciole, Gilberth Tadeu S.; Aciole, Jouber Mateus S.; Silveira, Landulfo, Jr.; Nunes dos Santos, Jean; Pinheiro, Antônio L. B.

    2011-03-01

    The aim of this study was to evaluate, through Raman spectroscopy, the repair of complete tibial fracture in rabbits fixed with wire osteosynthesis - WO, treated or not with infrared laser light (λ 780nm, 50mW, CW) associated or not to the use of HATCP and GBR. Surgical fractures were created under general anesthesia (Ketamine 0.4ml/Kg IP and Xilazine 0.2ml/Kg IP), on the tibia of 15 rabbits that were divided into 5 groups and maintained on individual cages, at day/night cycle, fed with solid laboratory pelted diet and had water ad libidum. On groups II, III, IV and V the fracture was fixed with WO. Animals of groups III and V were grafted with hydroxyapatite + GBR technique. Animals of groups IV and V were irradiated at every other day during two weeks (16J/cm2, 4 x 4J/cm2). Observation time was that of 30 days. After animal death the specimens were kept in liquid nitrogen for further analysis by Raman spectroscopy. Raman spectroscopy showed significant differences between groups (p<0.001). It is concluded that IR laser light was able to accelerate fracture healing and the association with HATCP and GBR resulted on increased deposition of calcium hydroxyapatite.

  6. Metallized Capillaries as Probes for Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Pelletier, Michael

    2003-01-01

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

  7. Raman Spectroscopy of Soft Musculoskeletal Tissues

    PubMed Central

    Esmonde-White, Karen

    2015-01-01

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

  8. Candida parapsilosis Biofilm Identification by Raman Spectroscopy

    PubMed Central

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

    2014-01-01

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

  9. Candida parapsilosis biofilm identification by Raman spectroscopy.

    PubMed

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

    2014-01-01

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

  10. Coherent Raman spectroscopy: From statics to dynamics and kinetics, progress in nonlinear methods

    NASA Astrophysics Data System (ADS)

    Akhmanov, S. A.

    1987-12-01

    In spite of its 60-year history Raman spectroscopy is still progressing nowadays. Highly stable lasers and short pulse oscillators, perfect electronic data acquisition systems, new nonlinear optical approaches created new exciting perspectives for Raman spectroscopy. One of the most important tendencies is Raman spectroscopy application for studying nonequilibrium states, fast dynamics and kinetics of atoms, molecules and condensed matter. All these problems were until recently regarded as inaccessible for optical spectroscopy. Nonlinear optical techniques of Coherent Anti-Stokes Raman Scattering (CARS) and modulation spectroscopy appeared to be most effective and provided important real-time information on molecular excitation and dissociation dynamics, deep cooling of molecules in a supersonic jet, short laser pulse induced phase transitions at semiconductor interface and so on. Problems yet to be solved include direct measurement of intramolecular vibrational relaxation, conformations in biomolecules, optical “oscilloscopy” of molecular vibrations.

  11. Development of a drug assay using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Angel, S. M.; Roe, Jeffrey N.; Andresen, Brian D.; Myrick, Michael L.; Milanovich, Fred P.

    1990-07-01

    Surface-enhanced Raman spectroscopy has been used to detect low levels of several chemical compounds, including the drugs of abuse -cocaine hydrochloride and methamphetamme hydrochloride. Raman spectra of these substances have also been taken over optical fibers using red-wavelength excitation. These measurements demonstrate the feasibility of the remote determination of various target chemicals using diode laser excitation and diode array detection.

  12. Raman spectroscopy of triolein under high pressures

    NASA Astrophysics Data System (ADS)

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

    2010-03-01

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

  13. In situ quantitative analysis of individual H2O-CO2 fluid inclusions by laser Raman spectroscopy

    USGS Publications Warehouse

    Azbej, T.; Severs, M.J.; Rusk, B.G.; Bodnar, R.J.

    2007-01-01

    Raman spectral parameters for the Raman ??1 (1285??cm- 1) and 2??2 (1388??cm- 1) bands for CO2 and for the O-H stretching vibration band of H2O (3600??cm- 1) were determined in H2O-CO2 fluid inclusions. Synthetic fluid inclusions containing 2.5 to 50??mol% CO2 were analyzed at temperatures equal to or greater than the homogenization temperature. The results were used to develop an empirical relationship between composition and Raman spectral parameters. The linear peak intensity ratio (IR = ICO2/(ICO2 + IH2O)) is related to the CO2 concentration in the inclusion according to the relation:Mole % C O2 = e- 3.959 IR2 + 8.0734 IRwhere ICO2 is the intensity of the 1388 cm- 1 peak and IH2O is the intensity of the 3600 cm- 1 peak. The relationship between linear peak intensity and composition was established at 350????C for compositions ranging from 2.5 to 50??mol% CO2. The CO2-H2O linear peak intensity ratio (IR) varies with temperature and the relationship between composition and IR is strictly valid only if the inclusions are analyzed at 350????C. The peak area ratio is defined as AR = ACO2/(ACO2 + AH2O), where ACO2 is the integrated area under the 1388??cm- 1 peak and AH2O is the integrated area under the 3600??cm- 1 peak. The relationship between peak area ratio (AR) and the CO2 concentration in the inclusions is given as:Mole % C O2 = 312.5 AR. The equation relating peak area ratio and composition is valid up to 25??mol% CO2 and from 300 to 450????C. The relationship between linear peak intensity ratio and composition should be used for inclusions containing ??? 50??mol% CO2 and which can be analyzed at 350????C. The relationship between composition and peak area ratios should be used when analyzing inclusions at temperatures less than or greater than 350????C (300-450) but can only be used for compositions ??? 25??mol% CO2. Note that this latter relationship has a somewhat larger standard deviation compared to the intensity ratio relationship. Calibration

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

    PubMed

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

    1998-01-01

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

  15. A novel method for the identification of inorganic and organic gunshot residue particles of lead-free ammunitions from the hands of shooters using scanning laser ablation-ICPMS and Raman micro-spectroscopy.

    PubMed

    Abrego, Zuriñe; Grijalba, Nagore; Unceta, Nora; Maguregui, Maite; Sanchez, Alicia; Fernández-Isla, Alberto; Goicolea, M Aranzazu; Barrio, Ramón J

    2014-12-01

    A method based on scanning laser ablation and inductively coupled plasma-mass spectrometry (SLA-ICPMS) and Raman micro-spectroscopy for the detection and identification of compounds consistent with gunshot residue particles (GSR) has been developed. The method has been applied to the characterization of particles resulting from the discharge of firearms using lead-free ammunition. Modified tape lifts were used to collect the inorganic and organic residues from skin surfaces in a single sample. Using SLA-ICPMS, aggregates related to the composition of the ammunition, such as Cu-Zn-Sn, Zr-Sr, Cu-Zn, Al-Ti, or Al-Sr-Zr were detected, but this composition is only consistent with GSR from lead-free ammunitions. Additional evidence was provided by micro-Raman spectroscopy, which identified the characteristic organic groups of the particles as centralite, diphenylamine or their nitrated derivatives, which are indicative of GSR. PMID:25303642

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

    NASA Astrophysics Data System (ADS)

    Cho, Soo Gyeong; Chung, Jin Hyuk

    2013-05-01

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

  17. Q-switched Raman laser system

    DOEpatents

    George, E.V.

    Method and apparatus for use of a Raman or Brillouin switch together with a conventional laser and a saturable absorber that is rapidly bleached at a predeterimined frequency nu = nu/sub O/, to ultimately produce a Raman or Brillouin pulse at frequency nu = nu/sub O/ +- nu /sub Stokes/.

  18. Q-Switched Raman laser system

    DOEpatents

    George, E. Victor

    1985-01-01

    Method and apparatus for use of a Raman or Brillouin switch together with a conventional laser and a saturable absorber that is rapidly bleached at a predetermined frequency .nu.=.nu..sub.0, to ultimately produce a Raman or Brillouin pulse at frequency .nu.=.nu..sub.0 .+-..nu..sub.Stokes.

  19. Raman spectroscopy of blood in-vitro

    NASA Astrophysics Data System (ADS)

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

    2012-03-01

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

  20. Uptake of and Resistance to the Antibiotic Berberine by Individual Dormant, Germinating and Outgrowing Bacillus Spores as Monitored by Laser Tweezers Raman Spectroscopy

    PubMed Central

    Wang, Shiwei; Yu, Jing; Suvira, Milomir; Setlow, Peter; Li, Yong-qing

    2015-01-01

    Berberine, an alkaloid originally extracted from the plant Coptis chinensis and other herb plants, has been used as a pharmacological substance for many years. The therapeutic effect of berberine has been attributed to its interaction with nucleic acids and blocking cell division. However, levels of berberine entering individual microbial cells minimal for growth inhibition and its effects on bacterial spores have not been determined. In this work the kinetics and levels of berberine accumulation by individual dormant and germinated spores were measured by laser tweezers Raman spectroscopy and differential interference and fluorescence microscopy, and effects of berberine on spore germination and outgrowth and spore and growing cell viability were determined. The major conclusions from this work are that: (1) colony formation from B. subtilis spores was blocked ~ 99% by 25 μg/mL berberine plus 20 μg/mL INF55 (a multidrug resistance pump inhibitor); (2) 200 μg/mL berberine had no effect on B. subtilis spore germination with L-valine, but spore outgrowth was completely blocked; (3) berberine levels accumulated in single spores germinating with ≥ 25 μg/mL berberine were > 10 mg/mL; (4) fluorescence microscopy showed that germinated spores accumulated high-levels of berberine primarily in the spore core, while dormant spores accumulated very low berberine levels primarily in spore coats; and (5) during germination, uptake of berberine began at the time of commitment (T1) and reached a maximum after the completion of CaDPA release (Trelease) and spore cortex lysis (Tlysis). PMID:26636757

  1. Drug Stability Analysis by Raman Spectroscopy

    PubMed Central

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

    2014-01-01

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

  2. Characterization of diatomaceous silica by Raman spectroscopy.

    PubMed

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

    2004-10-01

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

  3. Characterization of diatomaceous silica by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2004-10-01

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

  4. Drug stability analysis by Raman spectroscopy.

    PubMed

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

    2014-01-01

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

  5. Do laser/LED phototherapies influence the outcome of the repair of surgical bone defects grafted with biphasic synthetic microgranular HA + β-tricalcium phosphate? A Raman spectroscopy study.

    PubMed

    Soares, Luiz Guilherme Pinheiro; Marques, Aparecida Maria Cordeiro; Aciole, Jouber Mateus Santos; da Guarda, Milena Góes; Cangussú, Maria Cristina Teixeira; Silveira, Landulfo; Pinheiro, Antonio Luiz Barbosa

    2014-09-01

    The treatment of bone loss is difficult. Many techniques are proposed to improve repair, including biomaterials and, recently, phototherapies. This work studied bone mineralization by Raman spectroscopy assessing intensities of Raman peaks of both inorganic (∼ 960, ∼ 1,070 cm(-1)) and organic (∼ 1,454 cm(-1)) contents in animal model. Six groups were studied: clot, laser, light-emitting diode (LED), biomaterial (HA + β-tricalcium phosphate), laser + biomaterial, and LED + biomaterial. Defects at right tibia were performed with a drill. When indicated, defects were further irradiated at a 48-h interval during 2 weeks. At the 15th and 30th days, the tibias were withdrawn and analyzed. The ∼ 960-cm(-1) peak was significantly affected by phototherapy on both clot- and biomaterial-filled defects. The ∼ 1,070-cm(-1) peak was affected by both time and the use of the LED light on clot-filled defects. On biomaterial-filled defects, only the use of the laser light significantly influenced the outcome. No significant influence of either the time or the use of the light was detected on clot-filled defects as regards the ∼ 1,454-cm(-1) peak. Raman intensities of both mineral and matrix components indicated that the use of laser and LED phototherapies improved the repair of bone defects grafted or not with biphasic synthetic microgranular HA + β-tricalcium phosphate. PMID:24627284

  6. Bright emission from a random Raman laser

    PubMed Central

    Hokr, Brett H.; Bixler, Joel N.; Cone, Michael T.; Mason, John D.; Beier, Hope T.; Noojin, Gary D.; Petrov, Georgi I.; Golovan, Leonid A.; Thomas, Robert J.; Rockwell, Benjamin A.; Yakovlev, Vladislav V.

    2014-01-01

    Random lasers are a developing class of light sources that utilize a highly disordered gain medium as opposed to a conventional optical cavity. Although traditional random lasers often have a relatively broad emission spectrum, a random laser that utilizes vibration transitions via Raman scattering allows for an extremely narrow bandwidth, on the order of 10 cm−1. Here we demonstrate the first experimental evidence of lasing via a Raman interaction in a bulk three-dimensional random medium, with conversion efficiencies on the order of a few percent. Furthermore, Monte Carlo simulations are used to study the complex spatial and temporal dynamics of nonlinear processes in turbid media. In addition to providing a large signal, characteristic of the Raman medium, the random Raman laser offers us an entirely new tool for studying the dynamics of gain in a turbid medium. PMID:25014073

  7. Proposal for the measuring molecular velocity vector with single-pulse coherent Raman spectroscopy

    NASA Technical Reports Server (NTRS)

    She, C. Y.

    1983-01-01

    Methods for simultaneous measurements of more than one flow velocity component using coherent Raman spectroscopy are proposed. It is demonstrated that using a kilowatt broad-band probe pulse (3-30 GHz) along with a megawatt narrow-band pump pulse (approximately 100 MHz), coherent Raman signal resulting from a single laser pulse is sufficient to produce a high-resolution Raman spectrum for a velocity measurement.

  8. Detecting changes during pregnancy with Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

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

  9. Amplifier/compressor fiber Raman lasers.

    PubMed

    Islam, M N; Mollenauer, L F; Stolen, R H; Simpson, J R; Shang, H T

    1987-10-01

    We show that the chirp from cross-phase modulation (XPM) dominates the operation of fiber Raman lasers (FRL's). Thus a FRL in the anomalous group-velocity regime is best described as a XPM-chirped Raman amplifier followed by a linear fiber compressor. While the output of such a laser is generally a narrow pulse with a broad pedestal, we show both experimentally and by computer simulation that negligible background is achievable. PMID:19741882

  10. Single bacteria identification by Raman spectroscopy.

    PubMed

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

    2014-01-01

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