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1

Detection of diamond in ore using pulsed laser Raman spectroscopy  

Microsoft Academic Search

The viability of using pulsed laser excited Raman spectroscopy as a method for diamond detection from ore, has been investigated. In this method the spontaneous Stokes Raman signal is used as indicator of diamond, and a dual channel system is necessary for correcting for fluorescence of minerals and diamond itself. Various pulsed laser wavelengths from 266 to 1064nm were used,

G. H. Lamprecht; H. G. C. Human; L. W. Snyman

2007-01-01

2

Nonlinear Raman spectroscopy without tunable laser and application to lidar  

NASA Astrophysics Data System (ADS)

Various kinds of nonlinear Raman spectroscopy, such as coherent anti-Stokes Raman spectroscopy (CARS), stimulated Raman gain spectroscopy (SRGS), photo-acoustic Raman spectroscopy (PARS), and thermal-lens Raman spectroscopy (TLRS), can be applied for the detection of molecules in the atmosphere. In traditional nonlinear Raman spectroscopy, two lasers whose frequency difference was tuned to the Raman shift frequency had to be prepared. We proposed a new configuration using a Nd:YAG laser and a Raman prepared. We proposed a new configuration using a Nd:YAG laser and a Raman shifter. The Raman shifter contained the same kind of gas to be measured, so that efficient Raman-shifted beam was automatically generated in this simple configuration. We demonstrated sensitive detection of H2 and CH4 in the atmosphere by various kinds of nonlinear Raman spectroscopy above mentioned.The detection limit was approximately 1-30 ppm level in every method using a sample gas cell. In the case of SRGS, remote sensing is possible, and the detection sensitivity can be increased using long optical pass as in the absorption spectroscopy, because the signal is obtained by a coherent light beam and there is no limitation caused by phase-matching condition. Using the Mie scattering in the atmosphere as a distributed mirror, a new type of nonlinear Raman lidar can be constructed. In this paper, we discussed on the possibilities of long-pass and lidar measurement for the detection of CH4, H2 and CO2 by SRGS using a pulsed Nd:YAG laser.

Maeda, Mitsuo; Oki, Yuji; Nonaka, Yujii; Nakazono, Shinichiro; Vasa, Nilesh J.

2001-02-01

3

Evaluation of near-infrared laser Raman spectroscopy underwater research  

NASA Astrophysics Data System (ADS)

The in-situ chemical detection in deep sea is very important for mineral resources exploitation. Laser Raman Spectroscopy as a powerful tool for chemical analysis has been used in deep sea detection recently. It was found that the fluorescence always exists as the background on Raman spectra detecting in ocean. It is apparent that the fluorescence background could be decrease effectively using near infrared wavelength as excitation source. While near infrared laser has few application underwater due to the absorption of water in this wavelength range. In this paper, a 785nm Raman spectrometer was used to evaluate the near infrared laser Raman spectroscopy for underwater application. It was found that the Raman shift of SO4 2- at 981cm-1 can be easily detected from Qingdao near shore sea water samples without sever fluorescence background. With mixed solution of SO4 2- and HCO3 -, the detection limit achieved for SO4 2- at 981cm-1 and HCO3 - at 1017cm-1 was obtained by 785nm compact Raman spectrometer to be 0.00625mol/l and 0.025mol/l with 10s integration time respectively. The obtained results proved the feasibility of near infrared laser Raman underwater detection.

Guo, Jinjia; Zhang, Bin; Wu, Jianglai; Zheng, Ronger

2009-07-01

4

Grating-Stabilized External Cavity Diode Lasers for Raman Spectroscopy—A Review  

Microsoft Academic Search

Conventional Raman technique requires a continuous-wave laser with stabilized wavelength, narrow linewidth, and sufficient output power. Because of their miniature size and low cost, diode lasers are good choice as light sources for Raman spectroscopy, especially when compact and portable instruments are needed. However, a solitary multimode diode laser has certain drawbacks that limit its use for Raman application. To

Wenbo Wang; Arkady Major; Jitendra Paliwal

2011-01-01

5

Laser Raman Spectroscopy in studies of corrosion and electrocatalysis  

SciTech Connect

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.

Melendres, C.A.

1988-01-01

6

Ring-Down Spectroscopy for Characterizing a CW Raman Laser  

NASA Technical Reports Server (NTRS)

.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 abrupt switch-off, G1 is the initial rate of decay of the pump field, and G2 is the final rate of decay of the pump field. Hence, it is possible to determine all the parameters from a single ring-down scan, provided that the measurements taken in that scan are sufficiently accurate and complete.

Matsko, Andrey; Savchenkov, Anatoliy; Maleki, Lute

2007-01-01

7

[Rapid detection of chlorinated organic mixture by laser Raman spectroscopy].  

PubMed

In order to realize the rapid, nondestructive detection of organic compounds, a two-dimensional analysis method based on technology of laser Raman spectroscopy was proposed. The results show that using 532 nm laser as excitation light source, the observation of 236.2, 348.9, 449.4 and 513.6 cm(-1), the four vibrational Raman spectra, and the intensity ratio of 6.4 : 1.7: 9.4 : 1.0 can determine the existence of tetrachloroethylene. The observation of 707.5, 1 087.9, 1 175.8 and 3 078.6 cm(-1), the four vibrational Raman spectra, and the intensity ratio of 9.6 : 6.4 : 1.0 : 3.9 can determine the existence of chlorobenzene. In other words, that through the comprehensive study of spectral lines and intensity ratio of some spectral lines, the presence of organic compounds in the mixed solution can be determined quickly. In the aspect of quantitative analysis, using multi-spectral analysis combined with least square fitting method can improve the reliability of the measurement, The accuracy of sample concentration was 98.4%. This spectral measurement method is a potential tool for organic component identification and concentration analysis which has a prosperous application prospects. PMID:25269297

Ma, Jing

2014-07-01

8

Joint analyses by laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy at stand-off distances  

Microsoft Academic Search

Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) of solid samples have both been shown to be feasible with sample-to-instrument distances of many meters. The two techniques are very useful together, as the combination of elemental compositions from LIBS and molecular vibrational information from Raman spectroscopy strongly complement each other. Remote LIBS and Raman spectroscopy spectra were taken together on a

Roger C. Wiens; Shiv K. Sharma; Justin Thompson; Anupam Misra; Paul G. Lucey

2005-01-01

9

Raman Spectroscopy.  

ERIC Educational Resources Information Center

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…

Gerrard, Donald L.

1984-01-01

10

Novel probe for laser-induced breakdown spectroscopy and Raman measurements using an imaging optical fiber  

Microsoft Academic Search

A fiber-optic probe designed for remote laser-induced breakdown spectroscopy (LIBS), Raman spectroscopy, and Raman imaging has been developed for the microanalysis of solid samples. The probe incorporates both single-strand optical fibers and an image guide and allows atomic emission and Raman analysis of any spot on a solid sample within a 5 mm diameter field of view. The real-time sample

Brian J. Marquardt; Dimitra N. Stratis; S. M. Angel; D. A. Cremers

1998-01-01

11

Nonlinear Raman spectroscopy without tunable laser for sensitive gas detection in the atmosphere  

NASA Astrophysics Data System (ADS)

A new technique for photo-acoustic Raman spectroscopy (PARS) and coherent anti-Stokes Raman spectroscopy (CARS) is proposed and demonstrated for the detection of H 2 and CH 4 at atmospheric pressure. Conventionally, these types of nonlinear Raman spectroscopy require two lasers whose frequency difference is tuned to the Raman frequency. In the proposed scheme, only a pulsed Nd:YAG laser is used as a pumping source, and a Raman shifter filled with the same gas to be detected is combined. This allows automatic generation of the Raman-shifted radiation. In the case of CH 4, the measurement with the optimized scheme shows that detection limits up to 1 ppm for PARS and 15 ppm for CARS are achieved. The proposed PARS technique allows the measurement of the CH 4 concentration in the natural air. Although the sensitivity of CARS is lower than that of PARS, the signal to noise ratio (S/N) for higher concentrations is better.

Oki, Yuji; Kawada, Noriyuki; Abe, Yoshiteru; Maeda, Mitsuo

1999-03-01

12

NEW MICROSCOPIC LASER-COUPLED SPECTROSCOPY INSTRUMENT COMBINING RAMAN, LIBS, AND FLUORESCENCE FOR PLANETARY SURFACE MINERALOGY. J. Blacksberg1  

E-print Network

-resolved laser spectroscopy in a Figure 1. Image of our pulsed 532 nm microchip laser focused to ~ 1 µm spotNEW MICROSCOPIC LASER-COUPLED SPECTROSCOPY INSTRUMENT COMBINING RAMAN, LIBS, AND FLUORESCENCE (LIBS, Raman) have been the subject of increasing attention and development [e.g., 1, 2, 3] because

Rossman. George R.

13

Matrix Isolation Laser Raman Spectroscopy: The Raman Spectrum and Molecular Structure of Xenon Dichloride  

Microsoft Academic Search

The technique of matrix isolation infrared spectroscopy has proven on numerous occasions to be an extremely powerful tool for determining vibrational frequencies and molecular structures of highly reactive species. The need for reliable Raman data on comparable systems is obvious.

D. Boal; G. A. Ozin

1971-01-01

14

STUDIES OF MYOSIN AND ITS PROTEOLYTIC FRAGMENTS BY LASER RAMAN SPECTROSCOPY  

E-print Network

spectra were taken on a Spex Ramalog 4 system (Spex Industries, Inc., Metuchen, NJ) using an Ar+ laserSTUDIES OF MYOSIN AND ITS PROTEOLYTIC FRAGMENTS BY LASER RAMAN SPECTROSCOPY E. B. CAREW Department) but not in that of subfragment-l (S-1), is assigned to the coiled-coil tail region of myosin; the second, seen in spectra of S-1

Stanley, H. Eugene

15

Laser-induced breakdown spectroscopy and Raman microscopy for analysis of pigments in polychromes  

Microsoft Academic Search

A polychrome from the Rococo period was analysed by use of two laser-based analytical techniques, laser-induced breakdown spectroscopy (LIBS) and Raman microscopy. The analysis, performed on a fragment of a gilded altarpiece from the church of Escatrón, Zaragoza, Spain, provided detailed spectral data that have been used for the identification of pigments. LIBS measurements yielded elemental analytical data that suggest

Marta Castillejo; Margarita Mart??n; Diego Silva; Theodosia Stratoudaki; Demetrios Anglos; Lucia Burgio; Robin J. H Clark

2000-01-01

16

Analysis of pigments in polychromes by use of laser induced breakdown spectroscopy and Raman microscopy  

Microsoft Academic Search

Two laser-based analytical techniques, Laser Induced Breakdown Spectroscopy (LIBS) and Raman microscopy, have been used for the identification of pigments on a polychrome from the Rococo period. Detailed spectral data are presented from analyses performed on a fragment of a gilded altarpiece from the church of Escatrón, Zaragoza, Spain. LIBS measurements yielded elemental analytical data which suggest the presence of

M. Castillejo; M Mart??n; D. Silva; T. Stratoudaki; D. Anglos; L. Burgio; R. J. H Clark

2000-01-01

17

Detection of doxorubicin-induced apoptosis of leukemic T-lymphocytes by laser tweezers Raman spectroscopy  

PubMed Central

Laser tweezers Raman spectroscopy (LTRS) was used to acquire the Raman spectra of leukemic T lymphocytes exposed to the chemotherapy drug doxorubicin at different time points over 72 hours. Changes observed in the Raman spectra were dependent on drug exposure time and concentration. The sequence of spectral changes includes an intensity increase in lipid Raman peaks, followed by an intensity increase in DNA Raman peaks, and finally changes in DNA and protein (phenylalanine) Raman vibrations. These Raman signatures are consistent with vesicle formation, cell membrane blebbing, chromatin condensation, and the cytoplasm of dead cells during the different stages of drug-induced apoptosis. These results suggest the potential of LTRS as a real-time single cell tool for monitoring apoptosis, evaluating the efficacy of chemotherapeutic treatments, or pharmaceutical testing. PMID:21258536

Moritz, Tobias J.; Taylor, Douglas S.; Krol, Denise M.; Fritch, John; Chan, James W.

2010-01-01

18

Simultaneous Raman and laser-induced breakdown spectroscopy by a single setup  

NASA Astrophysics Data System (ADS)

A new experimental configuration is introduced for simultaneous recording of Raman and laser-induced breakdown spectroscopy (LIBS) in a single spectrum. A laser pulse is divided into two beams by a Glan-Taylor prism. By focusing one beam to the sample surface, micro-plasma is created and LIBS signal is emitted. The other beam is directed to the same point of the sample, but does not focused. The scattered light due to the second laser beam is mixed with the plasma emission and is recorded in a single spectrum. Atomic and molecular spectra of some minerals and chemical samples are recorded by the mentioned setup. Due to the high-plasma quenching in liquids, LIBS signals are not detected for organic liquid samples, instead a strong stimulated Raman signal is appeared, and as a result, an overlay of ordinary Raman with stimulated Raman is observed.

Matroodi, F.; Tavassoli, S. H.

2014-12-01

19

Joint analyses by laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy at stand-off distances.  

PubMed

Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS) of solid samples have both been shown to be feasible with sample-to-instrument distances of many meters. The two techniques are very useful together, as the combination of elemental compositions from LIBS and molecular vibrational information from Raman spectroscopy strongly complement each other. Remote LIBS and Raman spectroscopy spectra were taken together on a number of mineral samples including sulfates, carbonates and silicates at a distance of 8.3 m. The complementary nature of these spectra is highlighted and discussed. A factor of approximately 20 difference in intensity was observed between the brightest Raman line of calcite, at optimal laser power, and the brighter Ca I LIBS emission line measured with 55 mJ/pulse laser power. LIBS and Raman spectroscopy have several obstacles to devising a single instrument capable of both techniques. These include the differing spectral ranges and required detection sensitivity. The current state of technology in these areas is discussed. PMID:16029853

Wiens, Roger C; Sharma, Shiv K; Thompson, Justin; Misra, Anupam; Lucey, Paul G

2005-08-01

20

In vivo molecular evaluation of guinea pig skin incisions healing after surgical suture and laser tissue welding using Raman spectroscopy  

Microsoft Academic Search

The healing process in guinea pig skin following surgical incisions was evaluated at the molecular level, in vivo, by the use of Raman spectroscopy. After the incisions were closed either by suturing or by laser tissue welding (LTW), differences in the respective Raman spectra were identified. The study determined that the ratio of the Raman peaks of the amide III

A. Alimova; R. Chakraverty; R. Muthukattil; S. Elder; A. Katz; V. Sriramoju; Stanley Lipper; R. R. Alfano

2009-01-01

21

Investigate seawater and seawater anions' aqueous mixed solution by laser Raman spectroscopy  

Microsoft Academic Search

Laser Raman Spectroscopy (LRS) is a proven and powerful technique in geochemical analyses, especially in the study of seawater and seafloor hydrothermal minerals anions, such as SO 42-,CO32-,HCO3-, etc. In our lab we have used LD pumped Nd:YAG Laser operating at 532 nm which is selected for its relatively efficient propagation through seawater to investigate the LRS of seawater, Na2SO4-NaHCO3

Da Teng; Jun Ma; Yangyu Huang; Xining Zhang; Ronger Zheng

2008-01-01

22

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

NASA Astrophysics Data System (ADS)

We describe the design and operation of a spatially-filtered Raman/fluorescence spectrometer that incorporates a pulsed 532nm 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 5000K. We present performance comparisons of this system with that of a state-of-the-art conventional CW system using a 458nm 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 150GPa. This work suggests that Raman spectroscopy under conditions of very high temperatures (to 5000K) and/or ultrahigh pressures (to 300GPa) is entirely viable.

Goncharov, Alexander F.; Crowhurst, Jonathan C.

2005-06-01

23

Elemental Analysis of Environmental and Biological Samples Using Laser?Induced Breakdown Spectroscopy and Pulsed Raman Spectroscopy  

Microsoft Academic Search

Laser?induced breakdown spectroscopy (LIBS) and a relatively new technique, pulsed Raman spectroscopy (P?RAMS) are used in this investigation to measure the elemental composition of soils and heterogeneous biological matrices. The LIBS method was used effectively to determine the elemental concentration of carbon and nitrogen in soils, and the presence of metal contaminants in invertebrates. The P?RAMS method was used in

Madhavi Z. Martin; Stan D. Wullschleger; Charles T. Garten Jr; Anthony V. Palumbo; John G. Smith

2005-01-01

24

Investigate seawater and seawater anions' aqueous mixed solution by laser Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Laser Raman Spectroscopy (LRS) is a proven and powerful technique in geochemical analyses, especially in the study of seawater and seafloor hydrothermal minerals anions, such as SO 4 2-,CO 3 2-,HCO 3 -, etc. In our lab we have used LD pumped Nd:YAG Laser operating at 532 nm which is selected for its relatively efficient propagation through seawater to investigate the LRS of seawater, Na IISO 4-NaHCO 3 and Na IISO 4-Na IICO 3 aqueous mixed solutions of different established concentrations. The sample is interrogated by a 532 nm laser and the Raman backscattering radiation passes through grating and is recorded on a CCD camera. In the Raman spectrum of seawater near Qingdao sea area, we find SO 4 2- symmetric stretching band centered at ~981 cm -1 but neither CO 3 2- nor HCO 3 - signal could be observed . We have detected Raman spectra of mixed solutions and separated the Raman shift of anions from mixed Raman spectra, fitted the peak area and center with the method of the multi-peaks Gaussian Fit, then, used the ratios of the fitted areas (the ~981cm -1 band in SO 4 2-, the ~1066cm -1 band in CO 3 2- and ~1016cm -1 band in HCO 3 -) and established concentrations to estimate the Raman cross-section rations. The results show Gaussian Fit can effectively separate the Raman shifts of anions in mixed solution which close to each other and conform to the single solution's in the released papers. And we obtain relative Raman cross-sections ratios [SEE MANUSCRIPT FOR EQUATION] are 2.52 and 3.88 respectively at excitation wavelength 532nm.

Teng, Da; Ma, Jun; Huang, Yangyu; Zhang, Xining; Zheng, Ronger

2008-03-01

25

Remote Pulsed-Laser Raman Spectroscopy System for Mineral Analysis  

NASA Technical Reports Server (NTRS)

We have measured Raman spectra of carbonate, silicate, and hydrous silicate and sulfate minerals, our new remote-pulsed Raman system, indicating that it can be used to analyze the minerals on planetary surfaces to a distance of 10 to 66 meters. Additional information is contained in the original extended abstract.

Sharma, S. K.; Angel, S. M.; Ghosh, M.; Hubble, H. W.; Lucey, P. G.

2001-01-01

26

Laser Heated High Density Fluids Probed by Coherent Anti-Stokes Raman Spectroscopy  

SciTech Connect

We describe an integrated experimental method of Coherent Antistoke Raman Spectroscopy (CARS), laser-heating and diamond-anvil cell (DAC) technologies probing molecular vibrations of transparent molecular fluids at the pressure-temperature conditions of energetic detonation and Giant planetary interiors. In this method, we use a microfabricated metal toroid to conductively heat a surrounding transparent sample in a DAC, using a CW Nd:YLF laser. The laser is operated at a TEM{sub 01*} mode to match the shape of the toroid and thus produces a uniform heating area. The CARS probe utilizes two pulsed lasers with similar cavity lengths: a commercial narrow-band mode-locked Q-switched Nd:YAG laser and a home-built broadband dye laser. A strong CARS signal is then produced from the sample in the central region of laser-heated metal toroid where the two laser pulses spatially and temporally coincide. In this paper, we will demonstrate that this technique is capable of producing high quality vibrational spectra from nitrogen fluid above 2000 K and 13 GPa, where the application of spontaneous Raman spectroscopy is limited because of intense thermal radiation.

Baer, B J; Yoo, C

2004-05-19

27

In-situ characterization of meat aging with diode-laser Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Due to the narrow linewidth signals and its fingerprinting nature, Raman spectra provide information about the molecular structure and composition of the samples. In this paper, the applicability of Raman spectroscopy is shown for the in-situ characterization of the aging of meat. Miniaturized diode lasers are utilized as light sources with excitation wavelengths of 671 nm and 785 nm with a view to the development of a portable field device for meat. As test sample, musculus longissimus dorsi from pork was taken. The chops were stored refrigerated at 5 °C and Raman spectra were measured daily from slaughter up to three weeks. Throughout the entire period of one month, the Raman spectra preserve the basic spectral features identifying the samples as meat. More specific, the spectra exhibit gradual changes of the Raman signals and they show a time-dependent modification of the background signal which arises from a laser-induced fluorescence (LIF). To analyze the time-correlation of the complex spectra, multivariate statistical methods are employed. By means of principal components analysis (PCA) a distinction of spectra is found on the time scale between day 8 and 10. This corresponds to the transition from ripened meat to meat at and beyond the limit of inedibility. After ca. 10 days of storage at 5 °C the microbial load is overwhelming and LIF increases. The results of the Raman measurements depending on the storage time of meat are discussed in the context of reference analyses which have been performed in parallel.

Schmidt, Heinar; Blum, Jenny; Sowoidnich, Kay; Sumpf, Bernd; Schwägele, Fredi; Kronfeldt, Heinz-Detlef

2009-05-01

28

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

NASA Astrophysics Data System (ADS)

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 (?) and laser absorptivity (?). This new method is verified by comparing experimental results for graphite carbon fiber with measurement using the 3? method. The method was then used to measure the temperature dependent thermal diffusivity and thermal conductivity of individual carbon nanotubes.

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

2015-01-01

29

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

PubMed

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 (?) and laser absorptivity (?). This new method is verified by comparing experimental results for graphite carbon fiber with measurement using the 3? method. The method was then used to measure the temperature dependent thermal diffusivity and thermal conductivity of individual carbon nanotubes. PMID:25638107

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

2015-01-01

30

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

Microsoft Academic Search

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

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

2001-01-01

31

Remote pulsed laser Raman spectroscopy system for detecting water, ice, and hydrous minerals  

NASA Astrophysics Data System (ADS)

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 the 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.

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

2006-08-01

32

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

NASA Technical Reports Server (NTRS)

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.

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

33

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

NASA Astrophysics Data System (ADS)

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.

Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

2012-06-01

34

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

SciTech Connect

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.

Pal, Suparna; Aggarwal, R.; Kumari Gupta, Vandna; Ingale, Alka [Laser Physics Application Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, MP (India)

2014-07-07

35

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

NASA Astrophysics Data System (ADS)

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 InAsO4, As2O3 are formed upon oxidation, which are reflected as sharp Raman peaks at ˜240-254 and 180-200 cm-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.

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

2014-07-01

36

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

Microsoft Academic Search

Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532nm 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

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

2009-01-01

37

Improvements to a laser Raman spectroscopy system for reducing the false positives of autofluorescence bronchoscopies  

NASA Astrophysics Data System (ADS)

Preneoplastic lesions of the bronchial tree have a high probability of developing into malignant tumours. Currently the best method for localizing them for further treatment is a combined white light and autofluorescence bronchoscopy (WLB+AFB). Unfortunately the average specificity from large clinical trials for this combined detection method is low at around 60%, which can result in many false positives. However a recent pilot study showed that adding a point laser Raman spectroscopy (LRS) measurement improved the specificity of detecting lesions with high grade dysplasia or carcinoma in situ to 91% with a sensitivity of 96% compared to WLB+AFB alone. Despite this success, there is still room for much improvement. One constant need is to find better ways to measure the inherently weak Raman emissions in vivo which will result in even better diagnostic sensitivity and specificity. With this aim in mind a new generation Raman system was developed. The system uses the latest charge coupled device (CCD) with low noise, and fast cool down times. A spectrometer was incorporated that was able to measure both the low and high frequency Raman emissions with high resolution. The Raman catheter was also redesigned to include a visible light channel to facilitate the accurate indication of the area being measured. Here the benefits in the adjunct use of LRS to WLB + AFB are presented, and description of the new system and the improvements it offers over the old system are shown.

Pawluk, Hanna C.; Short, Michael A.; Lam, Stephen; McWilliams, Annette M.; Ionescue, Diana N.; Zeng, Haishan

2012-02-01

38

Organic semiconductor distributed feedback laser as excitation source in Raman spectroscopy using free-beam and fibre coupling  

NASA Astrophysics Data System (ADS)

Enabled by the broad spectral gain and the efficient energy conversion in the active material, organic semiconductor lasers are promising for spectroscopic applications and have been recently applied for high resolution absorption and transmission spectroscopy. Here, we present the application of organic semiconductor DFB laser (DFB-OSL) as excitation source in Raman spectroscopy. Utilizing an efficient small molecule blend of tris (8-hydroxyquinoline) aluminum (Alq3) doped with the laser dye 4-(dicyano-methylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM), our encapsulated DFB-OSL achieved a high slope efficiency of 7.6%. The organic lasers were tested in the inverted and upright Raman microscope setups, using free-beam and fibre coupling, respectively. In the free-beam configuration, the emission beam was guided directly into an inverted microscope. Employing a spectrally tunable DFBOSL as the excitation source, we measured the Raman spectra of sulfur and improved the Raman signals for a given optical filter configuration. In the fibre coupling configuration, the organic laser was coupled into a 50 ?m multi-mode optical fibre with an efficiency of 70 %. We utilized a round-to-line fibre-bundle for an efficient collection and transfer of Raman light to a spectrograph, by keeping a sufficient spectral resolution. Raman tests were performed on cadmium sulfide and cyclohexane. Our novel fibre-coupled organic laser provides a modular laboratory Raman system.

Liu, Xin; Lebedkin, Sergei; Mappes, Timo; Köber, Sebastian; Koos, Christian; Kappes, Manfred; Lemmer, Uli

2014-05-01

39

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

NASA Astrophysics Data System (ADS)

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.

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

2001-06-01

40

First experimental study of self-forming synthetic lipids by confocal laser tweezers Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We present the first experimental study of self-forming synthetic lipids, trademarked as QuSomesTM, using Raman spectroscopy in the spectral range of 500 to 3100 cm-1. Raman spectra of these new artificial lipids composed of 1,2- dimyristoyl-rac-glycerol-3-dodecaethylene glycol (GDM-12) and 1,2-dioleoyl-rac-glycerol-3-dodecaethylene glycol (GDO-12) have been obtained in pure form and in aqueous suspensions with Phosphate Buffered Saline (PBS) by using an inverted confocal laser-tweezers-Raman-microscopy system. This spectrometer works with an 80 mW diode-pumped solid-state laser, operating at a wavelength of 785 nm in the TEM00 mode. The laser is used both for optical trapping and Raman excitation. The two amphiphiles considered in this study, differ in their hydrophobic chain length and contain similar units of hydrophilic polyethylene glycol (PEG) head groups. Such synthetic PEG coated lipids exist in liquid form at room temperature and spontaneously form liposomes (nano type vesicles) upon hydration. In this work, we have focused on the band assignments for the spectra of single QuSomesTM nano particles in pure form and in aqueous media acquired by means of Raman spectroscopy. In particular, we have found that the most prominent peaks in the studied spectral region are dominated by vibrational modes arising from C-C and C-H bonds. Furthermore, we have noticed that some of the distinct peaks observed below 1800 cm-1 in pure sample are preserved in aqueous environment. These retained intense bands are located at 1449, 1128, 1079, and 1065 cm-1. This effect might be due to the strong chain-chain interactions, because the chains have to orient themselves and become tightly packed in the vesicles wall rather than adopt random orientations in bulk. This technique has proven to be an excellent tool to establish the fingerprint region revealing the molecular structure and conformation of QuSomesTM particles. The Raman spectroscopic data of these novel lipids and its vesicles formed in suspensions confirm high stability and are therefore considered as potential candidate for varieties of future applications including lipid based novel substances and drug delivery systems.

Bista, Rajan K.; Bruch, Reinhard F.

2008-06-01

41

Raman spectroscopy of organic dyes adsorbed on pulsed laser deposited silver thin films  

NASA Astrophysics Data System (ADS)

The results of a surface-enhanced Raman scattering (SERS) study performed on representative organic and inorganic dyes adsorbed on silver nanostructured thin films are presented and discussed. Silver thin films were deposited on glass slides by focusing the beam from a KrF excimer laser (wavelength 248 nm, pulse duration 25 ns) on a silver target and performing the deposition in a controlled Ar atmosphere. Clear Raman spectra were acquired for dyes such as carmine lake, garanza lake and brazilwood overcoming their fluorescence and weak Raman scattering drawbacks. UV-visible absorption spectroscopy measurements were not able to discriminate among the different chromophores usually referred as carmine lake (carminic, kermesic and laccaic acid), as brazilwood (brazilin and brazilein) and as garanza lake (alizarin and purpurin). SERS measurements showed that the analyzed samples are composed of a mixture of different chromophores: brazilin and brazilein in brazilwood, kermesic and carminic acid in carmine lake, alizarin and purpurin in garanza lake. Detection at concentration level as low as 10-7 M in aqueous solutions was achieved. Higher Raman intensities were observed using the excitation line of 632.8 nm wavelength with respect to the 785 nm, probably due to a pre-resonant effect with the molecular electronic transitions of the dyes.

Fazio, E.; Neri, F.; Valenti, A.; Ossi, P. M.; Trusso, S.; Ponterio, R. C.

2013-08-01

42

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

NASA Astrophysics Data System (ADS)

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.

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

2012-06-01

43

Chemical mapping of tulobuterol in transdermal tapes using microscopic laser Raman spectroscopy.  

PubMed

Microscopic Laser Raman Spectroscopy and Mapping (MLRSM) technique was used to investigate the distribution of tulobuterol (TBR) crystals in transdermal tapes. TBR is one of suitable compounds for the transdermal pharmaceuticals because it has high permeability into skin. In case of TBR transdermal tapes, some commercial products also contain TBR crystals in order to control a release rate from a matrix. Therefore, the presence of TBR crystals in the matrix is a critical factor for quality assurance of this type of TDDS tapes. The model tapes prepared here employed two kinds of matrices, i.e., rubber or acrylic, which are generally used for transdermal pharmaceuticals. TBR crystals in the matrix were observed by MLRSM. Accurate observation of the distribution of TBR in the tapes was achieved by creating a Raman chemical map based on detecting unique TBR peak in each pixel. Moreover, differences in the growth of TBR crystals in the two kinds of matrices were detected by microscopic observation. MLRSM also enabled the detection of TBR crystals in commercial products. The present findings suggest that Raman micro-spectroscopic analysis would be very useful for verifying and/or assessing the quality of transdermal pharmaceuticals in development, as well as for manufacturing process control. PMID:19348338

Sakamoto, T; Matsubara, T; Sasakura, D; Takada, Y; Fujimaki, Y; Aida, K; Miura, T; Terahara, T; Higo, N; Kawanishi, T; Hiyama, Y

2009-03-01

44

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

SciTech Connect

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 quantitatively determine the major elemental abundance of the remaining samples. PLS analysis suggests that the major element compositions can be determined with root mean square errors ca. 5% (absolute) for SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}(total), MgO, and CaO, and ca. 2% or less for TiO{sub 2}, Cr{sub 2}O{sub 3}, MnO, K{sub 2}O, and Na{sub 2}O. Finally, the Raman experiments have been conducted under supercritical CO{sub 2} involving single-mineral and mixed-mineral samples containing talc, olivine, pyroxenes, feldspars, anhydrite, barite, and siderite. The Raman data have shown that the individual minerals can easily be identified individually or in mixtures.

Clegg, Sanuel M [Los Alamos National Laboratory; Barefield, James E [Los Alamos National Laboratory; Humphries, Seth D [Los Alamos National Laboratory; Wiens, Roger C [Los Alamos National Laboratory; Vaniman, D. T. [Los Alamos National Laboratory; Sharma, S. K. [UNIV OF HAWAII; Misra, A. K. [UNIV OF HAWAII; Dyar, M. D. [MT. HOLYOKE COLLEGE; Smrekar, S. E. [JET PROPULSION LAB.

2010-12-13

45

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

SciTech Connect

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 flow cytometry, open up new possibilities for analyzing cellular processes occurring in single microbial and eukaryotic cells.

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

2007-01-09

46

Tunable excitation source for coherent Raman spectroscopy based on a single fiber laser  

E-print Network

was measured and vibrational resonant Raman peaks separated by 70?cm?1 were clearly resolved. Single laser-based tunable excitation may greatly simplify CRS measurements and extend the practicality of CRS microscopy....

Adany, Peter; Arnett, David C.; Johnson, Carey K.; Hui, Rongqing

2011-10-01

47

Sensitivity-enhanced transmission Raman spectroscopy.  

PubMed

Transmission Raman sensitivity for a representative commercial pharmaceutical tablet was increased by a factor of 40 using optics that returned lost laser and Raman photons to the tablet surface. A new achromatic one-way mirror is introduced that uses the spatial coherence of laser light to nondestructively force laser photons through the reflective tablet coating. Transmission Raman mapping and spatially offset Raman spectroscopy (SORS) mapping were developed and used to better understand the sensitivity-enhancement technology. Fundamental limitations of the sensitivity-enhancement approach are described and used to guide the design of the optics. The sensitivity-enhancement optics are compatible with commercial transmission Raman instruments. PMID:23876721

Pelletier, Michael J

2013-08-01

48

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

NASA Astrophysics Data System (ADS)

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 ?m. 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.

Glaus, Reto; Hahn, David W.

2014-10-01

49

RAMAN SPECTROSCOPY OF GRAPHENE AND RELATED MATERIALS  

E-print Network

, both exfoliated and synthesized, and graphene-based materials such as graphene-oxide. Graphene is a 2, and graphene-based materials such as graphene-oxide. Raman spectroscopy uses a monochromatic laser to interactChapter 19 RAMAN SPECTROSCOPY OF GRAPHENE AND RELATED MATERIALS Isaac Childres*a,b , Luis A

Chen, Yong P.

50

Raman Spectroscopy of Cocrystals  

NASA Astrophysics Data System (ADS)

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. )

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

2010-02-01

51

First experimental study of self-forming synthetic lipids by confocal laser tweezers Raman spectroscopy  

Microsoft Academic Search

We present the first experimental study of self-forming synthetic lipids, trademarked as QuSomesTM, using Raman spectroscopy in the spectral range of 500 to 3100 cm-1. Raman spectra of these new artificial lipids composed of 1,2- dimyristoyl-rac-glycerol-3-dodecaethylene glycol (GDM-12) and 1,2-dioleoyl-rac-glycerol-3-dodecaethylene glycol (GDO-12) have been obtained in pure form and in aqueous suspensions with Phosphate Buffered Saline (PBS) by using an

Rajan K. Bista; Reinhard F. Bruch

2008-01-01

52

Assessment of argon ion laser dispersive Raman spectroscopy for hot cell applications  

SciTech Connect

Characterization of high-level waste tank materials at Hanford is conducted to support safety assessments and waste treatment activities. Raman spectroscopy is expected to give chemical species information which may assist in defining layering in tank waste. This report describes the dispersive Raman system used in this year`s investigation and the methology used to collect and evaluate data taken on tank waste samples. The current argon-ion Raman system was found not to be suitable for screening of tank cores, owing to silica interference, fluorescence interferences, and the extensive time required to collect and treat the data. Recommendations are given for further development.

Crawford, B.A.

1995-02-24

53

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

SciTech Connect

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.

Mialichi, J. R.; Brasil, M. J. S. P.; Iikawa, F. [Instituto de Fisica 'Gleb Wataghin,' Unicamp, Campinas, 13083-859 Sao Paulo (Brazil); Verissimo, C.; Moshkalev, S. A. [Centro de Componentes Semicondutores, Unicamp, Campinas, 13083-870 Sao Paulo (Brazil)

2013-07-14

54

Water and surface contamination monitoring using deep UV laser induced native fluorescence and Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Reagentless water and surface sensors employing laser induced native fluorescence (LINF) and resonance Raman spectroscopy (RRS) in the deep UV are making significant progress in detecting chemical and biological targets and differentiating them against a wide range of background materials. Methods for optimizing sensor performance for specific target and backgrounds materials will be discussed in relationship to closed industrial environments and open natural environments. Limits of detection and chemical specificity will be discussed for high and low spectral resolution systems for a wide range of compounds and composite particles such as spores and cells. Detection and identification of single spores at working distance of several meters is illustrated. A range of sensors will be described along with their physical and performance specifications including sample, sipper and immersion sensors for water and fixed point and scanner systems for surfaces. In addition, the use of UV LINF and RRS for detection in capillary electrophoresis and liquid chromatography will be described with limits of detection in the range of a few nmol L -1.

Hug, William F.; Bhartia, Rohit; Tsapin, Alexandre; Lane, Arthur; Conrad, Pamela; Sijapati, Kripa; Reid, Ray D.

2006-10-01

55

Laser Raman micro-spectroscopy of Neoproterozoic - Early Palaeozoic organic-walled palynomorphs: palaeobiological interpretation  

NASA Astrophysics Data System (ADS)

Proterozoic and Palaeozoic organic walled microfossils (palynomorphs) comprise a wide range of organisms (e.g., oceanic photosynthetic microplankton, microzooplankton, and microscopic spores from earliest land plants), which characterize important evolutionary events in Earth's biosphere. For example, the evolutionary patterns and abundance fluctuations of acritarchs in the sedimentary records have been put in relation with changes in ocean chemistry, global glaciations, the diversification of metazoans, and variations in atmospheric CO2 concentration. Palynomorphs also record the transition of life from water (freshwater algae) to land (earliest miospores). Classical morphological comparative analytical methods are limited to those cases in which direct comparisons with extant organisms are available, but in many instances the biological affinities of pre-Devonian palynomorphs remain unknown. Recently, new techniques based on microchemical analysis of individual organic-walled microfossils demonstrated their potential for elucidating the cellular anatomy, composition, and mode of preservation of microfossils, thus offering new insights into their palaeobiology. In this study Laser Raman micro-spectroscopy was applied to a range of exceptionally well-preserved palynomorphs of late Neoproterozoic to early Devonian age, in order to better characterize their chemical composition. Raman spectra were successfully obtained from the studied palynomorphs; all showed characteristic bands attributable to C=C stretching for polycyclic aromatic compounds and contributions from CH2/CH3 bending. As in previously published MicroRaman spectra of organic-walled microfossils of varying age and state of preservation, the spectra reported here are characterized by two main lines at ~1350 and ~1600 cm-1 given by the so-called "D" (disordered) and "G" (graphitic) bands. These spectral features can be attributed to molecular subunits of interlinked aromatic hydrocarbons. It is important of notice that the position and shape of bands can vary between the species within the same sample, showing variability in the exact chemical composition depending on the species studied. For instance, the position of the main peak in the "D" region is placed at 1354 cm-1 in Navifusa majensis and Leiosphaeridia sp., whereas in Valeria lophostriata it is placed at 1375 cm-1. Similarly, the wavenumber of the "G" band is different, being 1600 cm-1 for the first two species and at 1577 cm-1 for Valeria lophostriata. Since these differences are taxon specific we suggest that they relate to the initial chemical and physical differences between the newly synthesised acritarch walls. The differences observed may be the preserved differences in chemistry of the biomacromolecules that comprised the original (not diagenetically modified) acritarch walls. Alternatively, the observed differences may only reflect result from differences between the original wall biomacromolecules, but no longer incorporate them since they have been entirely modified into geomacromolecules over time.

Vecoli, Marco; Dhamelincourt, Marie Claire; Mezzetti, Alberto; Cesari, Christian; Versteegh, Gerard

2010-05-01

56

[Laser tweezers Raman spectroscopy analysis of cold-adapted aromatic hydrocarbons-degradating strains isolated from Antarctic Sea].  

PubMed

Laser tweezers Raman spectroscopy can help with observing and studying individual cells or organelles in a natural state for a relatively long period. In the present experiment, Laser tweezers Raman spectroscopy (LTRS) was used as a tool to report physiological metabolism such as cells growth and nucleic acid, proteins, lipid and glucose of a single active cold-adapted Aromatic hydrocarbons-degradating strains isolated from Antarctic Sea. After the Raman spectrum was collected and analyzed, the findings are as follows: Raman spectrum identified the components of a single cold-adapted Aromatic hydrocarbons-degradating strain and there were more proteins and carbohydrate produced during the Planococcus sp. NJ41 and Shewanella sp. NJ49 growth and degradation; but there was more lipid than the proteins produced during the Pseudoalteromonas sp. NJ289 growth and degradation; the amount of proteins produced by the strains corresponds with the production of degradation rate-limiting enzyme, and was also related to the capacity of low-temperature degradation of aromatic hydrocarbons. PMID:21510394

Wang, Yi-Bin; Miao, Jin-Lai; He, Bi-Juan; Liang, Qiang; Liu, Fang-Ming; Zheng, Zhou

2011-02-01

57

In vivo Molecular Evaluation of Guinea Pig Skin Incisions Healing after Surgical Suture and Laser Tissue Welding Using Raman Spectroscopy  

PubMed Central

The healing process in guinea pig skin following surgical incisions was evaluated at the molecular level, in vivo, by the use of Raman spectroscopy. After the incisions were closed either by suturing or by laser tissue welding (LTW), differences in the respective Raman spectra were identified. The study determined that the ratio of the Raman peaks of the amide III (1247 cm?1) band to a peak at 1326 cm?1 (the superposition of elastin and keratin bands) can be used to evaluate the progression of wound healing. Conformational changes in the amide I band (1633 cm?1 to 1682 cm?1) and spectrum changes in the range of 1450 cm?1 to 1520 cm?1 were observed in LTW and sutured skin. The stages of the healing process of the guinea pig skin following LTW and suturing were evaluated by Raman spectroscopy, using histopathology 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. A wavelet decomposition-reconstruction baseline correction algorithm was employed to remove the fluorescence wing from the Raman spectra. PMID:19581109

Alimova, A.; Chakraverty, R.; Muthukattil, R.; Elder, S.; Katz, A.; Sriramoju, V.; Lipper, Stanley; Alfano, R. R.

2009-01-01

58

In vivo molecular evaluation of guinea pig skin incisions healing after surgical suture and laser tissue welding using Raman spectroscopy.  

PubMed

The healing process in guinea pig skin following surgical incisions was evaluated at the molecular level, in vivo, by the use of Raman spectroscopy. After the incisions were closed either by suturing or by laser tissue welding (LTW), differences in the respective Raman spectra were identified. The study determined that the ratio of the Raman peaks of the amide III (1247 cm(-1)) band to a peak at 1326 cm(-1) (the superposition of elastin and keratin bands) can be used to evaluate the progression of wound healing. Conformational changes in the amide I band (1633-1682 cm(-1)) and spectrum changes in the range of 1450-1520 cm(-1) were observed in LTW and sutured skin. The stages of the healing process of the guinea pig skin following LTW and suturing were evaluated by Raman spectroscopy, using histopathology 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. A wavelet decomposition-reconstruction baseline correction algorithm was employed to remove the fluorescence wing from the Raman spectra. PMID:19581109

Alimova, A; Chakraverty, R; Muthukattil, R; Elder, S; Katz, A; Sriramoju, V; Lipper, Stanley; Alfano, R R

2009-09-01

59

Nucleic acid and protein structures and interactions in viruses investigated by laser Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Raman spectroscopy may be profitably exploited to determine details of protein and nucleic acid structures and their mutual interactions in viruses and gene regulatory complexes. Present applications use data obtained from model nucleic acid crystals, fibers and solutions to reveal preferred backbone and nucleoside conformations for different morphological states of DNA and RNA in plant (TMV, BDMV) and bacterial viruses (P22, Pfl, Xf, Pf3, fd, Ifl, IKe). Interpretation of the results is enhanced by deconvolution methods which, in favorable cases, permit quantitative conclusions regarding macromolecular structures. Both equilibrium and dynamic Raman applications are described.

Thomas, George J.

1986-03-01

60

Ultrashort high repetition rate exposure of dielectric materials: laser bonding of glasses analyzed by micro-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report on the joining of different glass types with dissimilar optical, thermal and mechanical properties by ultrashort laser welding at high repetition rates. Femtosecond laser pulses were focused at the interface of two optically contacted transparent samples. Using nonlinear absorption processes and heat accumulation of successive pulses, we achieved strong bonds between the samples. We used a three-point bending test to determine the breaking strength. With this technique, we achieved for instance for a borosilicate glass a breaking strength of up to 95 % of the bulk material. In addition, we even welded different material combinations. Although the welded glasses exhibit different thermal and mechanical properties, we obtained breaking strengths which are comparable to the utilized bulk materials. Using Raman spectroscopy we mapped the laser-processed material along the welded interface. Thereby, we determined that the welds consist of a mixture of both species, which is formed during the laser induced melting of the materials.

Richter, S.; Zimmermann, F.; Döring, S.; Tünnermann, A.; Nolte, S.

2013-01-01

61

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

Microsoft Academic Search

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

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

2010-01-01

62

Study of sub-mJ-excited laser-induced plasma combined with Raman spectroscopy under Mars atmosphere-simulated conditions  

NASA Astrophysics Data System (ADS)

Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy are complimentary techniques. LIBS yields elemental information while Raman spectroscopy yields molecular information about a sample, and both share similar instrumentation configurations. The combination of LIBS and Raman spectroscopy in a single instrument for planetary surface exploration has been proposed, however challenges exist for developing a combined instrument. We present LIBS and Raman spectroscopy results obtained using a diode pumped, intracavity doubled, Q-switched, Nd:YLF laser operating at 523 nm, which overcomes some of the difficulties associated with a combined instrument. LIBS spectra were obtained with 170 ?J per pulse at 4 Hz repetition rate in a low pressure Mars-simulated atmosphere and Raman spectra produced with 200 mW at 100 kHz. The Nd:YLF laser is switchable between LIBS and Raman spectroscopy modes only by a change in Q-switch repetition rate. Emissions from Ca, Ca II, Fe, Fe II, Mg, Na, and O atom were identified in the ?-LIBS spectrum of oolithic hematite. Evidence was found for a change in plasma dynamics between 7 and 5 Torr that could be explained as a decrease in plasma temperature and electron density below 5 Torr. This is relevant to future Mars exploration using LIBS as the mean surface pressure on Mars varies from 3.75 to 6 Torr. LIBS plasma dynamics should be carefully evaluated at the pressures that will be encountered at the specific Mars landing site.

Dreyer, Christopher Brian; Mungas, Greg S.; Thanh, Phihung; Radziszewski, Juliez George

2007-12-01

63

Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

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.] -- Ultracold Ytterbium atoms in optical lattices / S. Sugawa ... [et al.] -- Ultracold polar molecules in the rovibrational ground state / J. Deiglmayr ... [et al.] -- Polar molecules near quantum degeneracy / J. Ye and D. S. Jin -- Production of a quantum gas of rovibronic ground-state molecules in an optical lattice / J. G. Danzl ... [et al.] -- Recent progress in x-ray nonlinear optics / K. Tamasaku, K. Sawada, and T. Ishikawa -- Gas in scattering media absorption spectroscopy - laser spectroscopy in unconventional environments / S. Svanberg -- Laser spectroscopy on relativistic ion beams / S. Reinhardt ... [et al.] -- Single frequency microcavity lasers and applications / L. Xu ... [et al.].

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

2010-02-01

64

Qualitative and quantitative analysis of CO2 and CH4 dissolved in water and seawater using laser Raman spectroscopy.  

PubMed

Laboratory experiments have been performed using laser Raman spectroscopy to analyze carbon dioxide (CO(2)) and methane (CH(4)) dissolved in water and seawater. Dissolved CO(2) is characterized by bands at approximately 1275 and 1382 Deltacm(-1). Dissolved CH(4) is characterized by a dominant band at approximately 2911 Deltacm(-1). The laboratory instrumentation used for this work is equivalent to the sea-going Raman instrument, DORISS (Deep Ocean Raman In Situ Spectrometer). Limits of quantification and calibration curves were determined for each species. The limits of quantification are approximately 10 mM for CO(2) and approximately 4 mM for CH(4). A ratio technique is used to obtain quantitative information from Raman spectra: the gas bands are referenced to the O-H stretching band of water. The calibration curves relating band height ratios to gas concentration are linear and valid for a range of temperatures, pressures, and salinities. Current instrumentation is capable of measuring the highest dissolved gas concentration observed in end-member hydrothermal fluids. Further development work is needed to improve sensitivity and optimize operational configurations. PMID:20615296

White, Sheri N

2010-07-01

65

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

PubMed

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

Moros, Javier; Javier Laserna, J

2015-03-01

66

Transient Bond Scission of Polytetrafluoroethylene under Laser-Induced Shock Compression Studied by Nanosecond Time-Resolved Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Nanosecond time-resolved Raman spectroscopy has been performed to study polymer films, polytetrafluoroethylene (PTFE), under laser driven shock compression at laser power density of 4.0 GW/cm2. The CF2 stretching mode line of PTFE showed a higher shift (18 cm-1) at delay time of 9.3 ns due to the shock compression and corresponding pressure was estimated to be approximately 2.3 GPa. A new vibrational line at 1900 cm-1 appeared only under shock compression and was assigned to the C=C stretching in transient species such as a monomer (C2F4) produced by the shock-induced bond scission. Intensity of the new line increased with increasing delay time along propagation of the shock compression.

Nakamura, Kazutaka G.; Wakabayashi, Kunihiko; Kondo, Ken-ichi

2002-07-01

67

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

PubMed

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:22225847

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

2012-06-10

68

Pulsed laser deposited Ag nanoparticles on nickel hydroxide nanosheet arrays for highly sensitive surface-enhanced Raman scattering spectroscopy  

NASA Astrophysics Data System (ADS)

In the present work, silver nanoparticles (NPs) were deposited on nickel hydroxide nanosheet (NS) arrays by pulsed laser deposition (PLD) for surface-enhanced Raman scattering (SERS) spectroscopy. The effective high specific surface area with silver NPs decorated on the NS arrays was revealed by field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). The microstructure and optical property of this three-dimensional (3D) substrate were investigated by X-ray diffraction (XRD) and UV-vis spectra, respectively. Using rhodamine 6G (R6G) as probe molecules with the concentration down to 10-5 M, the Ag/Ni(OH)2 composite film exhibits very high Raman scattering enhancement ability, possessing an enhancement factor as high as 5 × 106. It has been found that the enhancement ability of the substrate was strongly dependent on the size and interparticle gap of Ag NPs rather than the testing position on the film surface. In addition, the 3D structure of Ni(OH)2 NS arrays and the charge transfer of Ag NPs may be responsible for this high sensitivity Raman phenomenon.

Jing, Yuting; Wang, Huanwen; Chen, Xiao; Wang, Xuefeng; Wei, Huige; Guo, Zhanhu

2014-10-01

69

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)

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.

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

2009-08-01

70

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

PubMed

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

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

2009-08-01

71

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)

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.

Bohlin, Alexis; Kliewer, Christopher J.

2013-06-01

72

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...

73

Blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Concentrations of multiple analytes were simultaneously measured in whole blood with clinical accuracy, without sample processing, using near-infrared Raman spectroscopy. Spectra were acquired with an instrument employing nonimaging optics, designed using Monte Carlo simulations of the influence of light-scattering-absorbing blood cells on the excitation and emission of Raman light in turbid medium. Raman spectra were collected from whole blood drawn from 31 individuals. Quantitative predictions of glucose, urea, total protein, albumin, triglycerides, hematocrit, and hemoglobin were made by means of partial least-squares (PLS) analysis with clinically relevant precision (r2 values >0.93). The similarity of the features of the PLS calibration spectra to those of the respective analyte spectra illustrates that the predictions are based on molecular information carried by the Raman light. This demonstrates the feasibility of using Raman spectroscopy for quantitative measurements of biomolecular contents in highly light-scattering and absorbing media.

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

2002-11-01

74

IN SITU PLANETARY MINERALOGY USING SIMULTANEOUS TIME RESOLVED FLUORESCENCE AND RAMAN SPECTROSCOPY. J. Blacksberg1  

E-print Network

1. Image of our pulsed 532nm laser focusedIN SITU PLANETARY MINERALOGY USING SIMULTANEOUS TIME RESOLVED FLUORESCENCE AND RAMAN SPECTROSCOPY@gps.caltech.edu Introduction: Micro-Raman spectroscopy is one of the primary methods of mineralogical analysis

Rossman. George R.

75

Monitoring changes of proteins and lipids in laser welded aorta tissue using Raman spectroscopy and basis biochemical component analyses  

NASA Astrophysics Data System (ADS)

The changes of Raman spectra from ex-vivo porcine aorta tissues were studied before and after laser tissue welding (LTW). Raman spectra were measured and compared for normal and welded tissues in both tunica adventitial and intimal sides. The vibrational modes at the peak of 1301 cm-1 and the weak shoulder peak of 1264 cm-1 of amide III for the normal tissue changed to a peak at 1322cm-1 and a relative intense peak at 1264cm-1, respectively, for the welded tissue. The Raman spectra were analyzed using a linear regression fitting method and compared with characteristic Raman spectra from proteins and lipids compounds. The relative biochemical molecular composition changes of proteins (Collagen types I, III, V and Elastin) and lipids for the laser welded tissue were modeled by basis biochemical component analyses (BBCA) and compared with the normal tissue.

Liu, C. H.; Wang, W. B.; Alimova, A.; Sriramoju, V.; Kartazayev, V.; Alfano, R. R.

2009-02-01

76

Raman spectroscopy: the gateway into tomorrow's virology  

Microsoft Academic Search

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

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

2006-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

78

Characterization of Kevlar Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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.

Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

2007-01-01

79

High fidelity nanohole enhanced Raman spectroscopy.  

SciTech Connect

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.

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

2009-01-01

80

Photoacoustic Raman spectroscopy in molecular gases  

NASA Astrophysics Data System (ADS)

A novel method of nonlinear laser spectroscopy, photoacoustic Raman spectroscopy (PARS), is described. The differential equations governing the physical dimensions of the biharmonic light field in a PARS device are given, and an optimum geometry is found for the interaction of the light beams. A counterpropagating beam geometry is found to be the most practical scheme for increasing the strength of the recorded PARS signal. The increase in signal strength in comparison with unidirectional beam geometries is estimated near an order of magnitude. The effect of saturation due to two-frequency pumping in the Raman-active transition on the information content of PARS spectra is investigated, experimentally, using pure CO2 and other gas mixtures as laser active media. No significant decrease in the information content of the PARS spectra was observed.

Brodnikovskii, A. M.; Zharov, V. P.; Koroteev, N. I.

1985-12-01

81

In-situ laser Raman scattering and far infrared spectroscopy studies of corrosion-passivation phenomena in metals.  

SciTech Connect

Vibrational spectroscopic and electrochemical techniques are among the most useful tools for the elucidation of corrosion-passivation phenomena in metals. The former can provide information on the structure and composition of corrosion films ''in situ'' in aqueous solution environments, while thermodynamic and kinetic information may be obtained using electrochemical techniques. In this paper, we demonstrate the application of Laser Raman Scattering (LRS) and Synchrotrons Far Infrared Reflectance Spectroscopy (SFIRS), coupled with electrochemical methods, for the determination of the structure and composition of surface films on nickel and copper in aqueous solution environment. The corrosion film on nickel has been found to consist of NiO and Ni(OH){sub 2} in the passive region of potential and NiOOH in the transpassive region. The film on copper consists of Cu{sub 2}O, CUO and Cu(OH){sub 2}. We also show for the first time that SFIRS can be used to obtain information on the adsorption of ions on a metal surface with sub-monolayer sensitivity. Adsorption of Cl{sup {minus}}, Br{sup {minus}}, SO{sup {minus}2}, and PO{sub 4}{sup {minus}3} was found to occur at gold electrodes in perchloric acid solution. We also observed that when two different ions are present in solution, the more strongly adsorbed ion determined the corrosion behavior of the metal.

Melendres, C. A.

1999-06-28

82

Formation and Raman spectroscopy of single wall carbon nanotubes synthesized by CO 2 continuous laser vaporization  

Microsoft Academic Search

Single wall carbon nanotubes of tubule diameter 1.0–1.7nm were synthesized by the irradiation of continuous CO2 laser (500–900W) onto a graphite–Co\\/Ni composite target at room temperature. We suggest that the high temperature plays a unique key role in the growth of single-wall carbon nanotubes in the laser ablation method, while laser wavelength is less important. The transmission electron microscope observations

H. Zhang; K. Chen; Y. He; Y. Zhu; Y. Chen; C. Wu; J. Wang; J. H. Liao; S. H. Liu

2001-01-01

83

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)

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.

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

2010-02-01

84

Enthalpic and entropic stages in alpha-helical peptide unfolding, from laser T-jump/UV Raman spectroscopy.  

PubMed

The alpha-helix is a ubiquitous structural element in proteins, and a number of studies have addressed the mechanism of helix formation and melting in simple peptides. However, fundamental issues remain to be resolved, particularly the temperature (T) dependence of the rate. In this work, we report application of a novel kHz repetition rate solid-state tunable NIR (pump) and deep UV Raman (probe) laser system to study the dynamics of helix unfolding in Ac-GSPEA3KA4KA4-CO-D-Arg-CONH2, a peptide designed for helix stabilization in aqueous solution. Its T-dependent UV resonance Raman (UVRR) spectra, excited at 197 nm for optimal enhancement of amide vibrations, were decomposed into variable contributions from helix and coil spectra. The helix fractions derived from the UVRR spectra and from far UV CD spectra were coincident at low T but deviated increasingly at high T, the UVRR curve giving higher helix content. This difference is consistent with the greater sensitivity of UVRR spectra to local conformation than CD. After a laser-induced T-jump, the UVRR-determined helix fractions defined monoexponential decays, with time-constants of approximately 120 ns, independent of the final T (Tf = 18-61 degrees C), provided the initial T (Ti) was held constant (6 degrees C). However, there was also a prompt loss of helicity, whose amplitude increased with increasing Tf, thereby defining an initial enthalpic phase, distinct from the subsequent entropic phase. These phases are attributed to disruption of H-bonds followed by reorientation of peptide links, as the chain is extended. When Ti was raised in parallel with Tf (10 degrees C T-jumps), the prompt phase merged into an accelerating slow phase, an effect attributable to the shifting distribution of initial helix lengths. Even greater acceleration with rising Ti has been reported in T-jump experiments monitored by IR and fluorescence spectroscopies. This difference is attributable to the longer range character of these probes, whose responses are therefore more strongly weighted toward the H-bond-breaking enthalpic process. PMID:17910449

Balakrishnan, Gurusamy; Hu, Ying; Bender, Gretchen M; Getahun, Zelleka; DeGrado, William F; Spiro, Thomas G

2007-10-24

85

Femtosecond time-resolved Raman spectroscopy using stimulated Raman scattering  

Microsoft Academic Search

Femtosecond Raman spectroscopy has been developed to investigate ultrafast photoinduced structural changes of materials. Vibrational modes in the photogenerated transient species are measured by stimulated Raman scattering using a Raman pump pulse with narrow bandwidth and a femtosecond supercontinuum probe pulse. The Raman signal can be measured without slowing the temporal response and broadening the spectrum, because the temporal and

Masayuki Yoshizawa; Makoto Kurosawa

2000-01-01

86

Raman Spectroscopy of Microbial Pigments  

PubMed Central

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

Edwards, Howell G. M.; Oren, Aharon

2014-01-01

87

Heterodyne laser spectroscopy system  

DOEpatents

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.

Wyeth, Richard W. (Livermore, CA); Paisner, Jeffrey A. (San Ramon, CA); Story, Thomas (Antioch, CA)

1989-01-01

88

Heterodyne laser spectroscopy system  

DOEpatents

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.

Wyeth, Richard W. (Livermore, CA); Paisner, Jeffrey A. (San Ramon, CA); Story, Thomas (Antioch, CA)

1990-01-01

89

Superradiant Raman Laser Magnetometer  

E-print Network

We demonstrate a proof-of-principle magnetometer that relies on the active oscillation of a cold atom Raman laser to continuously map a field-sensitive atomic phase onto the phase of the radiated light. We demonstrate wideband sensitivity during continuous active oscillation, as well as narrowband sensitivity in passive Ramsey-like mode with translation of the narrowband detection in frequency using spin-echo techniques. The sensor operates with a sensitivity of 190 pT/Hz^(1/2) at 1 kHz and effective sensing volume of 2 * 10^-3 mm^3. Fundamental quantum limits on the magnetic field sensitivity of an ideal detector are also considered.

Weiner, Joshua M; Bohnet, Justin G; Chen, Zilong; Thompson, James K

2012-01-01

90

Superradiant Raman Laser Magnetometer  

E-print Network

We demonstrate a proof-of-principle magnetometer that relies on the active oscillation of a cold atom Raman laser to continuously map a field-sensitive atomic phase onto the phase of the radiated light. We demonstrate wideband sensitivity during continuous active oscillation, as well as narrowband sensitivity in passive Ramsey-like mode with translation of the narrowband detection in frequency using spin-echo techniques. The sensor operates with a sensitivity of 190 pT/Hz^(1/2) at 1 kHz and effective sensing volume of 2 * 10^-3 mm^3. Fundamental quantum limits on the magnetic field sensitivity of an ideal detector are also considered.

Joshua M. Weiner; Kevin C. Cox; Justin G. Bohnet; Zilong Chen; James K. Thompson

2012-10-13

91

Raman spectroscopy of Alzheimer's diseased tissue  

NASA Astrophysics Data System (ADS)

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.

Sudworth, Caroline D.; Krasner, Neville

2004-07-01

92

Remote adjustable focus Raman spectroscopy probe  

DOEpatents

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.

Schmucker, John E. (Hurt, VA); Blasi, Raymond J. (Harrison City, PA); Archer, William B. (Bethel Park, PA)

1999-01-01

93

Surface-Enhanced Raman Spectroscopy.  

ERIC Educational Resources Information Center

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)

Garrell, Robin L.

1989-01-01

94

Raman spectroscopy of advanced materials.  

PubMed

Many micro-structural aspects of advanced materials and the incidence on the physical properties have been elucidated by Raman micro-spectroscopy. The potential of this technique is demonstrated with new materials interesting in both academic and industrial developments: new carbons and diamonds, superconductors, semiconductors, superhards. PMID:15045323

Huong, P V

1996-06-01

95

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

PubMed

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 + ?-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 + ?-tricalcium phosphate. PMID:24627284

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

96

Integrated amplification and passivation nanolayers for ultra-high-sensitivity photodetector arrays: application for laser-induced breakdown spectroscopy (LIBS) and Raman spectroscopy  

Microsoft Academic Search

Miniaturized field-deployable spectrometers used for the rapid analysis of chemical and biological substances require high-sensitivity photo detectors. For example, in a Raman spectroscopy system, the receiver must be capable of high-gain, low-noise detection performance due to the intrinsically weak signals produced by the Raman effects of most substances. We are developing a novel, high-gain hetero-junction phototransistor (HPT) detector which employs

Patrick Gardner; Jie Yao; Sean Wang; Jack Zhou; Ken Li; Irina Mokina; Michael Lange; Weiguo Yang; Leora Peltz; Robert Frampton; Jeffrey H. Hunt; Jill Becker

2009-01-01

97

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

Microsoft Academic Search

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

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

2001-01-01

98

Simultaneous Conoscopic Holography and Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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 of laser light scattered inelastically from a laser-illuminated spot on the surface. The wavelengths of the inelastically scattered light differ from that of the incident laser beam by amounts that correspond to the energies of molecular vibrations. The resulting vibrational spectrum can be used to identify the molecules. Raman spectroscopy is a standard laboratory technique for identifying mineralogical, biological, and other specific chemical compositions.

Schramm, Harry F.; Kaiser, Bruce

2005-01-01

99

Planetary Surface Exploration Using Raman Spectroscopy on Rovers and Landers  

NASA Astrophysics Data System (ADS)

Planetary surface exploration using laser induced breakdown spectroscopy (LIBS) to probe the composition of rocks has recently become a reality with the operation of the mast-mounted ChemCam instrument onboard the Curiosity rover. Following this success, Raman spectroscopy has steadily gained support as a means for using laser spectroscopy to identify not just composition but mineral phases, without the need for sample preparation. The RLS Raman Spectrometer is included on the payload for the ExoMars mission, and a Raman spectrometer has been included in an example strawman payload for NASA’s Mars 2020 mission. Raman spectroscopy has been identified by the community as a feasible means for pre-selection of samples on Mars for subsequent return to Earth. We present a next-generation instrument that builds on the widely used green-Raman technique to provide a means for performing Raman spectroscopy without the background noise that is often generated by fluorescence of minerals and organics. Microscopic Raman spectroscopy with a laser spot size smaller than the grains of interest can provide surface mapping of mineralogy while preserving morphology. A very small laser spot size 1 µm) is often necessary to identify minor phases that are often of greater interest than the matrix phases. In addition to the difficulties that can be posed by fine-grained material, fluorescence interference from the very same material is often problematic. This is particularly true for many of the minerals of interest that form in environments of aqueous alteration and can be highly fluorescent. We use time-resolved laser spectroscopy to eliminate fluorescence interference that can often make it difficult or impossible to obtain Raman spectra. We will discuss significant advances leading to the feasibility of a compact time-resolved spectrometer, including the development of a new solid-state detector capable of sub-ns time resolution. We will present results on planetary analog minerals to demonstrate the instrument performance including fluorescence rejection.

Blacksberg, Jordana; Alerstam, E.; Maruyama, Y.; Charbon, E.; Rossman, G. R.

2013-10-01

100

The application of surface-enhanced Raman spectroscopy for the detection of excitatory amino acids  

E-print Network

enhanced Raman spectroscopy (SERS) on aqueous silver colloids. This study examines methods to monitor the colloidal reactions for the calibration of the enhancement observed. Thirty second Raman spectral scans were taken utilizing a 50 mW argon laser...

O'Neal, Dennis Patrick Doucet

2012-06-07

101

Laser Spectroscopy and Frequency Combs  

NASA Astrophysics Data System (ADS)

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.

Hänsch, Theodor W.; Picqué, Nathalie

2013-12-01

102

Raman accumulator as a fusion laser driver  

DOEpatents

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.

George, E. Victor (Livermore, CA); Swingle, James C. (Livermore, CA)

1985-01-01

103

Raman accumulator as a fusion laser driver  

DOEpatents

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.

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

1982-03-31

104

Raman spectroscopy of carbon nanotubes with electrostatically attached cytochrome c  

E-print Network

Spectroscopy in Life Science (Wiley-VCH, Weinheim, 2008) · Raman spectra recorded with 532 nm and 633 nm laser enhancement observed for metallic SWCNT at 532nm excitation wavelength assumption: effect is caused) No enhancement of RBMs for SWCNT-Cc in solution excessive Cc in the solution absorbs laser light at 532nm

Nabben, Reinhard

105

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 12061211  

E-print Network

of the depolarization ratio from photoacoustic Raman spectroscopy Yuanqin Yu, Ke Lin, Xiaoguo Zhou, Hua Wang, Shilin Liu is reported with an improved setup for photoacoustic Raman spectroscopy (PARS). The precise measurement molecules, such as CH4 and H2. The measured results of depolarization ratios agree well with the theoretical

Liu, Shilin

106

BRIEF COMMUNICATI-ON A LASER RAMAN SPECTROSCOPIC STUDY OF CA2+  

E-print Network

BRIEF COMMUNICATI-ON A LASER RAMAN SPECTROSCOPIC STUDY OF CA2+ BINDING TO TROPONIN C E. B. CAREW, P, Massachusetts 02139 U.S.A. ABSTRACT Laser Raman spectroscopy has been used to detect structural changes affinity Ca2+-specific sites is not detected by laser Raman spectral changes. INTRODUCTION Troponin C (Tn

Stanley, H. Eugene

107

Application of Raman Spectroscopy for Nondestructive Evaluation of Composite Materials  

NASA Technical Reports Server (NTRS)

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.

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

2007-01-01

108

Raman spectroscopies in shock-compressed materials  

SciTech Connect

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.

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

1983-01-01

109

Raman Spectroscopy of Ocular Tissue  

NASA Astrophysics Data System (ADS)

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 excised tissue samples and synthetic preparations and thus to identify potential biomarkers for the onset of this disease. Using resonance Raman detection techniques, the concentration and spatial distribution of macular pigment, a protective compound, can be detected in the living human retina Useable in clinical settings for patient screening, the technology is suitable to investigate correlations between pigment concentration levels and risk for macular degeneration and to monitor increases in pigment levels occurring as a result of dietary intervention strategies.

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

110

Improved accuracy of quantification of analytes in human body fluids by near-IR laser Raman spectroscopy with new algorithms  

NASA Astrophysics Data System (ADS)

Near infrared Raman spectroscopy has been successfully used to analyze ethanol and acetaminophen in human urine samples quantitatively. The new algorithms incorporating the intrinsic spectrum of the analyte of interest into the multivariate calibration were examined to improve the accuracy of the predicted concentrations. Comparing with commonly used partial least squares calibration, it was found that the methods using the intrinsic spectrum of the analyte of interest always achieved much higher accuracy, particularly when the interference from other undesired chemicals in the samples are severe.

Qu, Jianan Y.; Yau, On L.; Yau, SzeFong M.

1999-07-01

111

Surface-enhanced Raman spectroscopy of pterins  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

112

Raman spectroscopy for diagnosis of glioblastoma multiforme  

NASA Astrophysics Data System (ADS)

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 densities were evaluated in terms of mitochondrial oxidative/reductive activity as well as protein, RNA, and DNA syntheses. Although cell death was not significant, the cells' abilities to synthesize DNA, RNA, and protein were profoundly affected by the laser irradiation.

Clary, Candace Elise

113

Raman Spectroscopy: A Tool for Tissue Engineering  

Microsoft Academic Search

Raman spectroscopy can offer a non-invasive, information-rich biochemical “snapshot” of living human cells, tissues or material-cell\\u000a tissue constructs rapidly(seconds–minutes), without the need of labels or contrast enhancers. This chapter details the exciting\\u000a potential and challenges associated with the use of Raman spectroscopy in tissue engineering (TE). The use of Raman spectroscopy\\u000a in three interlinked areas of TE will be considered:

Gavin Jell; Robin Swain; Molly M. Stevens

114

In Vivo Analysis of Laser Preconditioning in Incisional Wound Healing of Wild-Type and HSP70 Knockout Mice With Raman Spectroscopy  

PubMed Central

Background and Objective Laser preconditioning augments incisional wound healing by reducing scar tissue and increasing maximum tensile load of the healed wound [.Wilmink et al. (2009) J Invest Dermatol 129(1): 205–216]. Recent studies have optimized treatments or confirmed results using HSP70 as a biomarker. Under the hypothesis that HSP70 plays a role in reported results and to better understand the downstream effects of laser preconditioning, this study utilized a probe-based Raman spectroscopy (RS) system to achieve an in vivo, spatiotemporal biochemical profile of murine skin incisional wounds as a function of laser preconditioning and the presence of HSP70. Study Design/Materials and Methods A total of 19 wild-type (WT) and HSP70 knockout (HSP70?/?) C57BL/ 6 mice underwent normal and laser preconditioned incisional wounds. Laser thermal preconditioning was conducted via previously established protocol (? = 1.85 µm, H0 =7.64 mJ/cm2 per pulse, spot diameter = 5 mm, Rep. rate = 50 Hz, ?p = 2 milliseconds, exposure time = 10 minutes) with an Aculight Renoir diode laser, with tissue temperature confirmed by real-time infrared camera measurements. Wound-healing progression was quantified by daily collection of a spatial distribution of Raman spectra. The results of RS findings were then qualified using standard histology and polarization microscopy. Results Raman spectra yielded significant differences (t-test; ? =0.05) in several known biochemical peaks between WT and HSP70 (?/?) mice on wounds and in adjacent tissue early in the wound-healing process. Analysis of peak ratios implied (i) an increase in protein configuration in and surrounding the wound in WT mice, and (ii) an increased cellular trend in WT mice that was prolonged due to laser treatment. Polarization microscopy confirmed that laser treated WT mice showed increased heterogeneity in collagen orientation. Conclusions The data herein supports the theory that HSP70 is involved in normal skin protein configuration and the cellularity of early wound healing. Laser preconditioning extends cellular trends in the presence of HSP70. Despite study limitations, RS provided a non-invasive method for quantifying temporal trends in altered wound healing, narrowing candidates and design for future studies with clinically applicable instrumentation. PMID:22275297

Makowski, Alexander J.; Davidson, Jeffrey M.; Mahadevan-Jansen, Anita; Jansen, E. Duco

2013-01-01

115

ExoMars Raman laser spectrometer overview  

NASA Astrophysics Data System (ADS)

The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. The RLS Instrument will perform Raman spectroscopy on crushed powered samples deposited on a small container after crushing the cores obtained by the Rover's drill system. This is the first time that a Raman spectrometer will be launched in an out planetary mission. The Instrument will be accommodated and operate inside the Rover's ALD (Analytical Laboratory Drawer), complying with COSPAR (Committee on Space Research) Planetary Protection requirements. The RLS Instrument is composed by the following units: SPU (Spectrometer Unit); iOH: (Internal Optical Head); ICEU (Instrument Control and Excitation Unit). Other instrument units are EH (Electrical Harness), OH (Optical Harness) and RLS SW On-Board.

Rull, F.; Sansano, A.; Díaz, E.; Canora, C. P.; Moral, A. G.; Tato, C.; Colombo, M.; Belenguer, T.; Fernández, M.; Manfredi, J. A. R.; Canchal, R.; Dávila, B.; Jiménez, A.; Gallego, P.; Ibarmia, S.; Prieto, J. A. R.; Santiago, A.; Pla, J.; Ramos, G.; González, C.

2010-09-01

116

Drug analysis by Raman and micro-Raman spectroscopy.  

PubMed

The technique of Raman spectroscopy, resonance Raman spectroscopy and micro-Raman spectroscopy is described for application to drug analysis and investigation. Possibilities and limits are mentioned for qualitative and quantitative analyses as well as for studies of structure and interactions. Some principal interaction modes, such as hydrogen bonding, proton transfer, charge transfer and ion-molecule attraction, are shown to explain drug reactivity. Illustrations are given based on several drug families, in particular vitamins, anti-depressants, cardio-active and anticancer drugs. PMID:16867562

Huong, P V

1986-01-01

117

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY  

E-print Network

MULTISCALE RECONSTRUCTION FOR PHOTON-LIMITED SHIFTED EXCITATION RAMAN SPECTROSCOPY Rebecca Willett excitation Raman spectroscopy results in multiple ob- servations of the sum of a material's fluorescent frequen- cies. The technique, known as Shifted Excitation Raman Difference Spectroscopy (SERDS

Willett, Rebecca

118

Raman Spectroscopy for the Biochemical Characterization of Bacteria Khozima Hamasha  

E-print Network

Raman Spectroscopy for the Biochemical Characterization of Bacteria Khozima Hamasha Department of Physics and Astronomy, Wayne State University, Detroit, Michigan, USA Raman spectroscopy (RS and discriminate different bacterial strains or study changes in bacterial cell composition. Raman spectroscopy

Rehse, Steven J.

119

Fourier Transform Raman Spectroscopy In Industrial Research  

NASA Astrophysics Data System (ADS)

Considering the importance of Raman spectroscopy as an analytical technique it is perhaps surprising that Raman spectrometers are seldom encountered in industrial laboratories and that so little work has been reported on samples of commercial interest. At least part of the reason for this can be traced to the large capital cost and the labour intensive nature of the sampling procedures. Even more significant, however, is the problem of fluorescence which more often than not totally obscures the Raman signal. Because of these difficulties Raman spectroscopy has played largely a secondary role and the unique information afforded from the Raman process has not been fully utilised.

Church, Stephen P.

1989-12-01

120

Proximal and point detection of contaminated surfaces using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

121

Femtosecond stimulated Raman spectroscopy of ultrafast biophysical reaction dynamics  

Microsoft Academic Search

I have developed the technique of femtosecond stimulated Raman spectroscopy (FSRS), which enables the rapid acquisition of vibrational spectra with <100-fs time-resolution and <15-cm-1 frequency-resolution. FSRS uses three laser pulses: (1) a femtosecond visible actinic pump that initiates the photochemistry, (2) a narrow bandwidth picosecond Raman pump that provides the energy for amplification of the probe, and (3) a femtosecond

David William McCamant

2004-01-01

122

Raman Spectroscopy and Related Techniques in Biomedicine  

PubMed Central

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

Downes, Andrew; Elfick, Alistair

2010-01-01

123

Raman spectroscopy of Xenopus laevis oocytes  

Microsoft Academic Search

This work reports on the application of Raman spectroscopy for the analysis of Xenopus laevis oocytes (stage-I). A two-color home-made microscope has been used for this investigation. In particular, a 785nm Raman probe has been used to acquire the spontaneous Raman scattering from the oocyte cytoplasm, while a 532nm probe has been employed to detect carotenoids through Resonant Raman Scattering.

Giulia Rusciano; Giuseppe Pesce; Marinella Salemme; Lara Selvaggi; Carmen Vaccaro; Antonio Sasso; Rosa Carotenuto

2010-01-01

124

Coherent raman spectroscopy of HCN complexes  

NASA Astrophysics Data System (ADS)

Photoacoustic Raman spectroscopy (PARS) is shown to be a sensitive technique for obtaining Raman spectra of hydrogen-bonded complexes in the gas phase. Coherent anti-Stokes Raman spectroscopy (CARS) provides analogous spectra in supersonic expansions. The effective resolution is higher in the latter case due to the cooling and collision-free conditions in the jet. The ability to "tune" complex size by changing expansion conditions is demonstrated in the case of HCN.

Hopkins, G. A.; Maroncelli, M.; Nibler, J. W.; Dyke, T. R.

1985-02-01

125

TOPICAL REVIEW: Prospects for in vivo Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2000-02-01

126

Raman spectroscopy in the analysis of food and pharmaceutical nanomaterials.  

PubMed

Raman scattering is an inelastic phenomenon. Although its cross section is very small, recent advances in electronics, lasers, optics, and nanotechnology have made Raman spectroscopy suitable in many areas of application. The present article reviews the applications of Raman spectroscopy in food and drug analysis and inspection, including those associated with nanomaterials. Brief overviews of basic Raman scattering theory, instrumentation, and statistical data analysis are also given. With the advent of Raman enhancement mechanisms and the progress being made in metal nanomaterials and nanoscale metal surfaces fabrications, surface enhanced Raman scattering spectroscopy has become an extra sensitive method, which is applicable not only for analysis of foods and drugs, but also for intracellular and intercellular imaging. A Raman spectrometer coupled with a fiber optics probe has great potential in applications such as monitoring and quality control in industrial food processing, food safety in agricultural plant production, and convenient inspection of pharmaceutical products, even through different types of packing. A challenge for the routine application of surface enhanced Raman scattering for quantitative analysis is reproducibility. Success in this area can be approached with each or a combination of the following methods: (1) fabrication of nanostructurally regular and uniform substrates; (2) application of statistic data analysis; and (3) isotopic dilution. PMID:24673902

Li, Ying-Sing; Church, Jeffrey S

2014-03-01

127

Crystalline and Fiber Raman Lasers  

Microsoft Academic Search

This chapter describes the state of the art of crystalline and fiber Raman lasers based on the simulated Raman scattering\\u000a (SRS) effect in crystals and silica-based fibers. It includes historical and theoretical background, analysis of properties\\u000a of known and newly developed high-efficient SRS crystals, such as LiIO3, Ba(NO3)2, NaNO3, PbNO3, CaCO3, KGW, BaWO4, SrWO4,BaMoO4,SrMoO4, PbWO4, and germanosilicate and phosphosilicate fibers.

T. Basiev; V. Osiko; A. Prokhorov; E. Dianov

128

Raman spectroscopy and its urological applications  

PubMed Central

Purpose: The Raman spectroscopic technology can be utilized for the detection of changes occurring at the molecular level during the pathological transformation of the tissue. The potential of its use in urology is still in its infancy and increasing utility of this technology will transform noninvasive tissue diagnosis. The Nobel laureate, Sir C.V. Raman is credited for the discovery of the principles of Raman spectroscopy. Materials and Methods: Applications of Raman spectroscopy in the bladder, renal, prostate, and other urological disorders were gathered from Medline and abstracts from recent international urological meetings. Current status and future directions of Raman spectroscopy in urology were also reviewed. Results: Raman spectroscopic technology is used to interrogate biological tissues. The potential use of this technology in urology has shown encouraging results in the in vitro diagnosis and grading of cancers of the bladder and the prostate. Raman microprobes have been used for the characterization and identification of renal lithiasis. Technology may be available for the urologists to determine the margin status intraoperatively during partial nephrectomy and radical prostatectomy. The future would see the development of optical fiber probes to incorporate them into catheters, endoscopes, and laparoscopes that will enable the urologist to obtain information during the operation. Conclusion: Raman spectroscopy is an exciting tool for real-time diagnosis and in vivo evaluation of living tissue. The potential applications of Raman spectroscopy may herald a new future in the management of various malignant, premalignant, and other benign conditions in urology. PMID:19468494

Hanchanale, Vishwanath S.; Rao, Amrith R.; Das, Sakti

2008-01-01

129

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

PubMed

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

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

2013-09-01

130

Resonance coherent anti-stokes Raman spectroscopy  

Microsoft Academic Search

Conditions to get Coherent Anti-Stokes Raman Spectra for strong one-photon-resonance are given. The biharmonic pump was realized by a high power ns-ruby-laser and a broadband dye-laser, focussed together into a small sample cell. Resonance Raman spectra of an extension of some hundreds cm-1 are obtained during one laser shot, thus opening possibilities to investigate excited electronic states or short-living molecules.

A. Lau; W. Werncke; J. Klein; M. Pfeiffer

1977-01-01

131

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2008; 39: 593598  

E-print Network

2007 Focus-engineered coherent anti-Stokes Raman scattering (FE-CARS) microscopy is used to highlight the lateral interfaces between chemically distinct media. Interface highlighting is achieved by using a HG10 mode for the Stokes laser beam and a HG00 mode for the pump laser beam in the forward detection scheme

Potma, Eric Olaf

132

In vivo Raman spectroscopy of cervix cancers  

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

133

Raman spectroscopy: the gateway into tomorrow's virology  

PubMed Central

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

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

2006-01-01

134

Demonstration of a silicon Raman laser  

Microsoft Academic Search

We report the demonstration of the first silicon Raman laser. Experimentally, pulsed Raman laser emission at 1675 nm with 25 MHz repetition rate is demonstrated using a silicon waveguide as the gain medium. The laser has a clear threshold at 9 W peak pump pulse power and a slope efficiency of 8.5%.

Ozdal Boyraz; Bahram Jalali

2004-01-01

135

Sampling Methods In FT-Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

The extension of the Raman technique to the use of excitation wavelengths in the near infrared shows much promise, especially for samples exhibiting strong fluorescence when excited by the visible lasers used in dispersive Raman instrumentation. The dependence of the Raman signal on the fourth power of the excitation wavelength has precluded the common use of near infrared excitation due to signal to noise considerations.

Brierley, Philip R.; Rosenthal, Robert J.

1989-12-01

136

Raman spectroscopy in the diagnosis of ulcerative colitis.  

PubMed

Introduction?At present, the diagnosis of ulcerative colitis (UC) requires the histologic demonstration of characteristic mucosal inflammatory changes. A rapid and noninvasive diagnosis would be of value, especially if it could be adapted to a simple rectal probe. Raman spectroscopy creates a molecular fingerprint of substances by detecting laser light scattered from asymmetric, vibrating, and chemical bonds. We hypothesize that Raman spectroscopy can distinguish UC from non-UC colon tissue rapidly and accurately. Materials and Methods?Colon tissue specimens were obtained from patients operated at the Children's Hospital of Michigan, United States, including UC colon and non-UC colon. The samples were examined with a Renishaw inVia Raman microscope (Gloucestershire, United Kingdom) with a 785?nm laser. Principal component analysis and discriminant function analysis were used to classify groups. Final classification was evaluated against histologic diagnoses using leave-one-out cross-validation at a spectral level. Results?We compared Raman spectroscopy examination of colon specimens from four patients with UC and four patients without UC. A total of 801 spectra were recorded from colon specimens. We evaluated 100 spectra each from the mucosal and serosal surfaces of patients with UC and 260 spectra from the mucosal surface and 341 spectra from the serosal surface of the patients who did not have UC. For samples from the mucosal surface, the Raman analysis had a sensitivity of 82% and a specificity of 89%. For samples from the serosal surface, Raman spectroscopy had a sensitivity of 87% and a specificity of 93%. When considering each tissue sample and deciding the diagnosis based on the majority of spectra from that sample, there were no errors in the diagnosis. Conclusions?Raman spectroscopy can distinguish UC from normal colon tissue rapidly and accurately. This technology offers the possibility of real-time diagnosis as well as the ability to study changes in UC-afflicted colon tissue that do not appear histologically. PMID:25172984

Veenstra, Michelle Anne; Palyvoda, Olena; Alahwal, Hazem; Jovanovski, Marko; Reisner, Luke Anthony; King, Brady; Poulik, Janet; Klein, Michael D

2015-02-01

137

Raman spectroscopy for noninvasive glucose measurements  

E-print Network

We report the first successful study of the use of Raman spectroscopy for quantitative, noninvasive (“transcutaneous”) measurement of blood analytes, using glucose as an example. As an initial evaluation of the ability of ...

Enejder, Annika M. K.

138

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...

139

[Study on the treatment turquoise using Raman spectroscopy].  

PubMed

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

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

2010-07-01

140

Pulsed-ultraviolet laser Raman diagnostics of plasma processing discharges  

SciTech Connect

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.

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

1988-11-07

141

Raman spectroscopy of Xenopus laevis oocytes.  

PubMed

This work reports on the application of Raman spectroscopy for the analysis of Xenopus laevis oocytes (stage-I). A two-color home-made microscope has been used for this investigation. In particular, a 785nm Raman probe has been used to acquire the spontaneous Raman scattering from the oocyte cytoplasm, while a 532nm probe has been employed to detect carotenoids through Resonant Raman Scattering. Finally, the distribution of beta-carotene along a diameter of a single oocyte has been investigated. PMID:20035873

Rusciano, Giulia; Pesce, Giuseppe; Salemme, Marinella; Selvaggi, Lara; Vaccaro, Carmen; Sasso, Antonio; Carotenuto, Rosa

2010-05-01

142

Fourier Transform Raman Spectroscopy In The Near Infrared - Industrial Applications And Limitations  

NASA Astrophysics Data System (ADS)

In the past the application of Raman spectroscopy as an analytical tool has been severely restricted by laser induced fluorescence. It has been demonstrated recently 1,2, that near infrared Fourier Transform Raman spectroscopy can offer a solution to this problem. Near infrared laser excitation energy is, in general, too low to excite fluorescence. Unfortunately, the scattered Raman intensity is inversely proportional to the fourth power of the wavelength. This leads to a reduction in intensity of a factor of 22 on moving from 514.5 nm to 1064.1 nm excitation. Also, near infrared detectors are orders of magnitude less sensitive than photomultipliers used in conventional Raman spectroscopy. Despite these restrictions the FT-Raman technique opens up new possibilities for Raman spectroscopy.

Shurvell, H. F.; Bergin, F. J.

1989-12-01

143

Potential of Raman and Infrared Spectroscopy for Plant Analysis  

NASA Astrophysics Data System (ADS)

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.

Schulz, H.

2008-11-01

144

Vibrational Raman Spectroscopy of High-temperature Superconductors  

E-print Network

Vibrational Raman Spectroscopy of High-temperature Superconductors C. Thomsen and G. Kaczmarczyk Reproduced from: Handbook of Vibrational Spectroscopy John M. Chalmers and Peter R. Griffiths (Editors) John Wiley & Sons Ltd, Chichester, 2002 #12;Vibrational Raman Spectroscopy of High

Nabben, Reinhard

145

Mobile Raman spectroscopy in astrobiology research.  

PubMed

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

Vandenabeele, Peter; Jehli?ka, Jan

2014-12-13

146

Solid state lasers with Raman frequency conversion  

Microsoft Academic Search

Stimulated Raman scattering (SRS) in solid state crystals has become a well-established nonlinear frequency conversion technique with the increasing number of applications. Summary of an experimental investigation of SRS in unique solid state Raman-active materials (BaWO4, KGW, CaCO3) is presented. Examples of picosecond and nanosecond Raman laser development are described in various pump configurations. Comparison of Raman crystal converters is

Helena Jel??nková; Peter G Zverev; Tasoltan T Basiev

2004-01-01

147

Surface vibrational spectroscopy using stimulated Raman scattering  

Microsoft Academic Search

We propose a new method for studying surface vibrational spectroscopy based on an extension of the picosecond stimulated Raman gain technique. This technique is extremely surface sensitive and can detect coverages of 1 percent of a monolayer. This technique does not require ultrahigh vacuums (as do electron spectroscopies), is an extremely sensitive probe of surface local fields, has very high

BARRY F. LEVINE; CHARLES V. SHANK; J. P. HERITAGE

1979-01-01

148

Recognition of gastric cancer by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The purpose of this study was to explore near-infrared (NIR) Raman spectroscopy for distinguishing cancer from normal gastric tissue. In our study, a total of 236 Raman spectra of mucosa from 43 gastric cancer patients were obtained by NIR Raman spectroscopy system with an excitation wavelength of 785 nm. After pretreatment, a comparison of the Raman spectra between cancer and normal tissues occurred. It was found that the gastric cancerous mucosa showed lower intensities at around 748, 944, and 1520cm-1, while higher at 807 and 1661cm-1, compared with normal tissue. And there was only one peak at 1022cm-1 in the spectra of normal mucosa, while there were two peaks at 1022 and 1052cm-1 in the spectra of cancerous mucosa. Support Vector Machine (SVM) was employed to classify Raman spectra between cancer and normal gastric tissues. A sensitivity of 88.2%, a specificity of 91.9%, and an overall diagnostic accuracy of 90.3% were achieved for discriminating gastric cancer from normal tissues with a Radial Basic Function (RBF) SVM algorithm. The experimental results show that Raman spectra differed significantly between cancerous and normal gastric tissue, which provides the experimental basis for the diagnosis of gastric cancer by Raman spectroscopy technology. And RBF SVM algorithm can give the well generalized classification performance for the samples, which expands the application of mathematical algorithms in the classification.

Xu, Ming; Ma, Jun; Qu, Yefei; Mao, Weizheng; Zheng, Ronger

2009-08-01

149

Imaging EGFR distribution using surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2009-02-01

150

Laser-induced chemical transformation of PATP adsorbed on Ag nanoparticles by surface-enhanced Raman spectroscopy-A study of the effects from surface morphology of substrate and surface coverage of PATP.  

PubMed

The laser induced transformation of p-aminothiophenol (PATP) to p,p'-dimercaptoazobenzene (DMAB) has attracted intensive interest recently, in which localized surface plasmon resonance (LSPR) assisted photocatalysis has been demonstrated to play an important role. In this paper, we systematically investigate the factors that influence the reaction for further understanding the mechanism using surface-enhanced Raman spectroscopy. The laser-induced formation of DMAB was found to depend on the surface coverage of PATP, the aggregation state of NPs, and the laser power. The disappearance of DMAB Raman signal at very low concentration of Ag NPs reveals that DMAB may only be formed between the neighboring NPs that can provide a suitable distance for the interaction between adsorbed PATP molecules. PMID:25467654

Xu, Jian-Fang; Liu, Guo-Kun

2015-03-01

151

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

NASA Astrophysics Data System (ADS)

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 ?m). 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.

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

2013-10-01

152

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

SciTech Connect

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 ?m). 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.

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

2013-10-28

153

Transmission fourier transform Raman spectroscopy of pharmaceutical tablet cores.  

PubMed

Transmission Fourier transform (FT) Raman spectroscopy of pharmaceutical tablet cores is demonstrated using traditional, unmodified commercial instrumentation. The benefits of improved precision over backscattering Raman spectroscopy due to increased sample volume are demonstrated. Self-absorption effects on analyte band ratios and sample probe volume are apparent, however. A survey of near-infrared (NIR) absorption spectra in the FT-Raman spectral range (approximately 0 to 3500 wavenumber shift from 1064 nm, or 1064 to 1700 nm) of molecules with a wide range of NIR-active functional groups shows that although absorption at the laser wavelength (1064 nm) is relatively small, some regions of the Raman spectrum coincide with NIR absorbances of 0.5 per cm or greater. Fortunately, the pharmaceutically important regions of the Raman shift spectrum from 0 to 600 cm(-1) and from 1400 to 1900 cm(-1) exhibit low self-absorption for most organic materials. A statistical analysis of transmission FT-Raman noise in spectra collected from different regions of a pharmaceutical tablet provides insight into both spectral distortion and reduced sampling volume caused by self-absorption. PMID:22449328

Pelletier, Michael J; Larkin, Peter; Santangelo, Matthew

2012-04-01

154

Raman Spectroscopy Study of Prostatic Adenocarcinoma Bulk Tissues  

NASA Astrophysics Data System (ADS)

Prostate cancer is one of the most common types of cancer among men. The mortality rate for this disease can be dramatically reduced if it can be diagnosed in its early stages. Raman spectroscopy is one of the optical techniques which can provide fingerprints of a disease in terms of its molecular composition which changes due to the onset of disease. The aim of this project is to investigate the differences in the Raman spectra to identify benign epithelium (BE), prostatic intraepithelial neoplasia (PIN) and adenocarcinoma of various Gleason grades in archived bulk tissues embedded in paraffin wax. For each tissue, two adjacent tissue sections were cut and dewaxed, where one of the sections was stained using haematoxylin and eosin for histological examination and the other unstained adjacent section was used for Raman spectroscopic studies. We have collected Raman spectra from 10 prostatic adenocarcinoma dewaxed tissue sections using Raman microscope (785 nm excitation laser). The data were analyzed using statistical methods of principal component analysis and discriminant function analysis to classify the tissue regions. The results indicate that Raman Spectroscopy can differentiate between BE, PIN and Cancer regions.

Devpura, S.; Dai, H.; Thakur, J. S.; Naik, R.; Cao, A.; Pandya, A.; Auner, G. W.; Sarkar, F.; Sakr, W.; Naik, V.

2009-03-01

155

Multiplex coherent raman spectroscopy detector and method  

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

156

Observations of Ferroelastic Switching by Raman Spectroscopy  

E-print Network

. The incident laser light comes in through the top diamond and the returning Raman scatter and ruby luminescence are collected. ........................................................................ 28 xii Page Figure 17. White light and Raman images... of an indented region in the bulk material. a) Image of the indent with radial cracks emanating from the corners of the indent. The dashed box highlights the edges of the diamond indent. The solid boxes the location of regions of banding as seen...

Bolon, Amy Marie

2012-02-14

157

NQR and Raman spectroscopy study of ?-dichlorobiphenyl  

Microsoft Academic Search

Pulsed 0953-8984\\/8\\/21\\/016\\/img9 nuclear quadrupole resonance (NQR) and Raman spectroscopy studies were performed to get information about the structural and dynamic thermal behaviour of the 0953-8984\\/8\\/21\\/016\\/img10 dichlorobiphenyl. NQR measurements of the line-shape and the spin - lattice relaxation time 0953-8984\\/8\\/21\\/016\\/img11 were obtained in the temperature range 80 K - 320 K. Raman spectra from powder samples were recorded for temperatures between

J. Schneider; A. Wolfenson; A. Brunetti; L. A. de O. Nunes

1996-01-01

158

Laser annealing of implanted silicon carbide and Raman characterization  

Microsoft Academic Search

Pulsed-laser-based methods have been applied for post-implant annealing of p-type Al doped 4H-SiC wafers in order to restore the crystal structure and to electrically activate the doping species. The annealing was performed with the second (532nm) and third (355nm) harmonic of a Nd:YAG laser at 4ns pulse duration. The epilayers were characterized by micro-Raman spectroscopy under surface and cross sectional

I. Zergioti; A. G. Kontos; K. Zekentes; C. Boutopoulos; P. Terzis; Y. S. Raptis

2006-01-01

159

Coherent Raman spectro-imaging with laser frequency combs  

NASA Astrophysics Data System (ADS)

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.

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

2013-10-01

160

Raman and multichannel Raman spectroscopy of biological systems  

NASA Astrophysics Data System (ADS)

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.

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

1991-05-01

161

Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

162

Temperature dependent Raman spectroscopy of ZnO nanowires  

E-print Network

Temperature dependent Raman spectroscopy of ZnO nanowires Rodolfo López Jr and Yi Gu Department Conduction Band Valence Band a) Insulator b) Semiconductor c) Superconductor Energy of Electrons RamanO wires on gold/silicon substrate Raman spectroscopy was conducted by (a) a Raman microscope in (b

Collins, Gary S.

163

Coherent Raman spectroscopy for supersonic flow measurments  

NASA Technical Reports Server (NTRS)

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.

She, C. Y.

1986-01-01

164

Raman spectroscopy investigation of magnetite nanoparticles in ferrofluids  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is used to investigate magnetite nanoparticles dispersed in two types of ?-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 ?-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.

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

2010-07-01

165

Raman spectroscopy in investigation of rheometric processes  

NASA Astrophysics Data System (ADS)

Studies of application of Raman spectroscopy in measurement of important parameters of rheometric process, including profile of oil film thickness and composition of oil/paste system, were carried out. The films of silicone oil AK106 (Wacker) extracted from ceramic paste AlOOH were subjects of investigations presented in this paper. Boundary between oil film and extruded paste is not regular and ambiguous during the extrusion process of ceramic paste in capillary rheometer. Moreover, the pastes are scattering materials, what makes determination of the film thickness by conventional optical methods difficult. Preliminary Raman measurements were made separately for oil and paste samples in range extending from 50 to 3500 cm-1. Determination of main Raman bands assigned to oil, ceramics and glass showed that Raman spectroscopy enables discernment of these materials. During the next step, studies were conducted for a model sample of the oil spread on the paste, using Raman microscope. This device was equipped with long-working-distance objective which should enable remote measurements through a borosilicate, view-port-window in the wall of capillary rheometry die. Two methods of Raman determination of the thickness were compared. Results of analysis and experimental works suggest that one of them can be applied for in-situ monitoring of the extrusion process.

Gnyba, Marcin; Bogdanowicz, Robert; Kozanecki, Marcin

2005-09-01

166

Coherent Raman dual-comb spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

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.

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

2014-11-01

167

Probing Strain-Induced Electronic Structure Change in Graphene by Raman Spectroscopy  

E-print Network

measurements, we employed a confocal configuration with laser wavelength of 532 nm (except for measurementProbing Strain-Induced Electronic Structure Change in Graphene by Raman Spectroscopy Mingyuan Huang of Physics, Columbia University, New York, New York 10027 ABSTRACT Two-phonon Raman scattering in graphitic

Heinz, Tony F.

168

Q-Switched Raman laser system  

DOEpatents

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.

George, E. Victor (Livermore, CA)

1985-01-01

169

Requirements for Calibration in Noninvasive Glucose Monitoring by Raman Spectroscopy  

E-print Network

233 Requirements for Calibration in Noninvasive Glucose Monitoring by Raman Spectroscopy Jan Lipson% of the data in the Clarke A and B ranges. Conclusions: Because Raman spectroscopy has high discrimination in Noninvasive Glucose Monitoring by Raman Spectroscopy Lipson www.journalofdst.orgJ Diabetes Sci Technol Vol 3

Hammerton, James

170

Physica E 26 (2005) 1418 Infrared and Raman spectroscopies of  

E-print Network

Physica E 26 (2005) 14­18 Infrared and Raman spectroscopies of InP/II­VI core-shell nanoparticles F Available online 13 January 2005 Abstract We use infrared (IR) and Raman spectroscopies to investigate: Core-shell nanoparticles; IR; Raman spectroscopy; Temperature behavior; Confined modes The prospects

Weinstein, Benard.A.

171

A combined remote Raman and LIBS instrument for characterizing minerals with 532 nm laser excitation  

Microsoft Academic Search

The authors have developed an integrated remote Raman and laser-induced breakdown spectroscopy (LIBS) system for measuring both the Raman and LIBS spectra of minerals with a single 532nm laser line of 35mJ\\/pulse and 20Hz. The instrument has been used for analyzing both Raman and LIBS spectra of carbonates, sulfates, hydrous and anhydrous silicates, and iron oxide minerals in air. These

Shiv K. Sharma; Anupam K. Misra; Paul G. Lucey; Rachel C. F. Lentz

2009-01-01

172

Bladder cancer diagnosis during cystoscopy using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

173

Spatially offset Raman spectroscopy (SORS) for liquid screening  

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

174

Tunable continuous-wave diamond Raman laser.  

PubMed

Continuous-wave operation of a diamond Raman laser, intracavity-pumped by a diode-pumped InGaAs semiconductor disk laser (SDL), is reported. The Raman laser, which utilized a 6.5-mm-long synthetic single-crystal diamond, reached threshold for 5.3 W of diode laser pump power absorbed by the SDL. Output power up to 1.3 W at the first Stokes wavelength of 1227 nm was demonstrated with excellent beam quality and optical conversion efficiency of 14.4% with respect to absorbed diode laser pump power. Broad tuning of the Raman laser output between 1217 and 1244 nm was achieved via intracavity tuning of the SDL oscillation wavelength. PMID:22109443

Parrotta, Daniele C; Kemp, Alan J; Dawson, Martin D; Hastie, Jennifer E

2011-11-21

175

Bright emission from a random Raman laser  

PubMed Central

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

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

176

Estimating Atomic Sizes with Raman Spectroscopy  

E-print Network

and technology, such as designing, fabricating, and diagnosing nano materials and structures in the level of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China, 2 Wuhan Institute of Physics into the nano-scale channels of a zeolite single crystal. We found their polarized Raman spectroscopy, which

Du, Shengwang

177

Raman spectroscopy of blue gel pen inks  

Microsoft Academic Search

Raman spectroscopy is becoming a tool of major importance in forensic science. It is a non-invasive, non-destructive analytical method allowing samples to be examined without any preparation. This paper demonstrates the use of the technique as a general tool for gel pen inks analysis. For this purpose, 55 blue gel pen inks, of different brands and models representative of gel

Williams David Mazzella; Patrick Buzzini

2005-01-01

178

FT-Raman spectroscopy study of human breast tissue  

NASA Astrophysics Data System (ADS)

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.

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

2004-07-01

179

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

NASA Astrophysics Data System (ADS)

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.

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

2012-01-01

180

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

PubMed

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 SO(4)(2-) 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. PMID:22947647

Bajpai, P K; Verma, A L

2012-10-01

181

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

182

[Laser Raman spectrum analysis of carbendazim pesticide].  

PubMed

Raman signal of solid and liquid carbendazim pesticide was collected by laser Raman spectrometer. The acquired Raman spectrum signal of solid carbendazim was preprocessed by wavelet analysis method, and the optimal combination of wavelet denoising parameter was selected through mixed orthogonal test. The results showed that the best effect was got with signal to noise ratio (SNR) being 62.483 when db2 wavelet function was used, decomposition level was 2, the threshold option scheme was 'rigisure' and reset mode was 'sln'. According to the vibration mode of different functional groups, the de-noised Raman bands could be divided into 3 areas: 1 400-2 000, 700-1 400 and 200-700 cm(-1). And the de-noised Raman bands were assigned with and analyzed. The characteristic vibrational modes were gained in different ranges of wavenumbers. Strong Raman signals were observed in the Raman spectrum at 619, 725, 964, 1 022, 1 265, 1 274 and 1 478 cm(-1), respectively. These characteristic vibrational modes are characteristic Raman peaks of solid carbendazim pesticide. Find characteristic Raman peaks at 629, 727, 1 001, 1 219, 1 258 and 1 365 cm(-1) in Raman spectrum signal of liquid carbendazim. These characteristic peaks were basically tallies with the solid carbendazim. The results can provide basis for the rapid screening of pesticide residue in food and agricultural products based on Raman spectrum. PMID:25358165

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

2014-06-01

183

Titanium-enhanced Raman microcavity laser.  

PubMed

Whispering gallery mode microcavities are ideally suited to form microlaser devices because the high circulating intensity within the cavity results in ultralow lasing thresholds. However, to achieve low-threshold Raman lasing in silica devices, it is necessary to have quality factors above 100 million. One approach to circumvent this restriction is to intercalate a sensitizer into the silica, which increases the Raman gain. In the present work, we demonstrate a Raman laser based on a titanium sensitized silica solgel coated toroidal microcavity. By tuning the concentration of the Ti, the Raman efficiency improves over 3× while maintaining sub-mW thresholds. PMID:24690786

Deka, Nishita; Maker, Ashley J; Armani, Andrea M

2014-03-15

184

Detection Of Biochips By Raman And Surface Enhanced Raman Spectroscopies  

NASA Astrophysics Data System (ADS)

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 ?-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.

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

2010-08-01

185

The effect of aqueous solution in Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In Raman detection, the most popular solution for the samples is tri-distilled water. But the effect of aqueous solution is barely studied in Raman spectroscopy. In fact Raman spectroscopy of solid-state and liquid-state are obvious different. In addition, FWHM of Raman spectral peaks also change evidently. In this paper, several samples were selected for the experiment; including sodium nitrate, sodium nitrite, glucose and caffeine. By comparing the Raman spectroscopy of samples at different concentrations, it is found that the concentration of the sample can affect the strength of Raman spectroscopy, but it can hardly impact FWHM of Raman spectral peaks. By comparing the Raman spectroscopy of liquid-state with the Raman spectroscopy of solid-state, it is observed that the FWHM of some Raman spectral peaks varied obviously; that may be because when the sample was dissolved into the water, the crystal lattice structure was broken, and for some samples atom form became ion form in aqueous solution. Those structural variations caused the variation of the FWHM. The Raman spectroscopy of caffeine aqueous solution at very low concentration was also detected and analyzed. Compared with the Raman spectra of solid-state samples, it is found that some Raman spectral peaks disappeared when the sample was dissolved in water. It is possible that the low concentration of the sample result in the weakening of Raman signals and the disappearing of some weak Raman spectral peaks. Then Ag nanoparticles were added into the caffeine aqueous solution, the results suggest that surface enhanced Raman spectroscopy (SERS) not only can enhance the Raman spectral signal, but also can reduce the effect of aqueous solution. It is concluded that the concentration of sample only affects the strength of Raman spectroscopy; the aqueous solution can affect the FWHM of Raman spectral peaks; and SERS can reduce the effect of aqueous solution.

Kang, Jian; Yuan, Xiaojuan; Dong, Xiao; Gu, Huaimin

2009-08-01

186

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

USGS Publications Warehouse

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 relationships employing peak areas for both members of the Fermi diad (??1 at 1285??cm- 1 and 2??2 at 1388??cm- 1) were slightly poorer than those using only the 2??2 (1388??cm- 1) member owing to interference from quartz peak at approximately 1160??cm- 1. The technique has been applied to natural low-salinity H2O-CO2 inclusions from the Butte, Montana, porphyry copper-molybdenum deposit. Carbon dioxide concentrations obtained range from below detection to 4.2??mol% CO2, and are in good agreement with concentrations determined previously based on microthermometric and petrographic observations. ?? 2007 Elsevier B.V. All rights reserved.

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

2007-01-01

187

Candida parapsilosis Biofilm Identification by Raman Spectroscopy  

PubMed Central

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

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

2014-01-01

188

Raman Spectroscopy of Soft Musculoskeletal Tissues  

PubMed Central

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

Esmonde-White, Karen

2015-01-01

189

Laser annealing of implanted silicon carbide and Raman characterization  

NASA Astrophysics Data System (ADS)

Pulsed-laser-based methods have been applied for post-implant annealing of p-type Al doped 4H-SiC wafers in order to restore the crystal structure and to electrically activate the doping species. The annealing was performed with the second (532nm) and third (355nm) harmonic of a Nd:YAG laser at 4ns pulse duration. The epilayers were characterized by micro-Raman spectroscopy under surface and cross sectional backscattering. Changes in the phonon mode-intensity were related to the laser annealing induced recrystallization of the implanted material. The results were compared with changes in the infrared reflectivity across the Restsrahlen band.

Zergioti, I.; Kontos, A. G.; Zekentes, K.; Boutopoulos, C.; Terzis, P.; Raptis, Y. S.

2006-05-01

190

Development of a rapid macro-Raman spectroscopy system for nasopharyngeal cancer detection based on surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

This study aims to evaluate the utility of a home-made surface-enhanced Raman spectroscopy (SERS) system for detection of nasopharyngeal cancer (NPC). A Raman spectral system with a special probe and a millimeter order excitation laser spot size was developed to acquire SERS signals of blood plasma. High quality SERS spectra can be recorded from blood plasma samples belonging to 60 healthy volunteers and 96 NPC patients, and the diagnostic sensitivity and specificity of 95.8% and 91.7%, respectively, can be achieved for classification between normal and cancer blood groups by principal component analysis combined with linear discriminant analysis (PCA-LDA). This exploratory study demonstrates that SERS based on a larger laser spot together with PCA-LDA has the potential for detection of nasopharyngeal cancer, and even for further in vivo cancer detection in the future.

Lin, Duo; Chen, Guannan; Feng, Shangyuan; Pan, Jianji; Lin, Juqiang; Huang, Zufang; Chen, Rong

2015-01-01

191

Femtosecond stimulated Raman spectroscopy of beta-carotene's ultrafast relaxation processes  

Microsoft Academic Search

We have developed the novel technique of femtosecond stimulated Raman spectroscopy (FSRS) to measure vibrational spectra on the femtosecond time scale. FSRS bypasses the time\\/energy resolution limitations of traditional Raman spectroscopy, simultaneously allowing 100 fs time-resolution and 15 cm-1 frequency resolution. The experiment utilizes three laser pulses: (1) a 40 fs visible pump pulse, used to initiate the photochemistry; (2)

Richard A. Mathies; David McCamant; Philip Kukura

2003-01-01

192

Raman laser amplification in preformed and ionizing plasmas  

E-print Network

wave-breaking; Laser ionization; Laser-plasma interaction; Raman laser amplification; Raman scatteringRaman laser amplification in preformed and ionizing plasmas D.S. CLARK1 and N.J. FISCH2 1 Lawrence the effects of FRS and modulational instabilities, and of Langmuir wave breaking on the output intensity

193

Raman spectroscopy of blood in-vitro  

NASA Astrophysics Data System (ADS)

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.

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

2012-03-01

194

Drug Stability Analysis by Raman Spectroscopy  

PubMed Central

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

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

2014-01-01

195

Drug stability analysis by Raman spectroscopy.  

PubMed

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

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

2014-01-01

196

Near infrared Raman spectroscopy for Alzheimer's disease detection  

NASA Astrophysics Data System (ADS)

In recent years, the use of Raman spectroscopy for the detection and diagnosis of disease has steadily grown within the research field. However, this research has primarily been restricted to oncology. This research expands the use of Raman spectroscopy as a potential tool for the diagnosis of Alzheimer's disease, which is currently the most prevalent, and fastest growing type of dementia in the Western world. Using a commercial Raman spectrometer (Renishaw PLC ®, UK) flash frozen post-mortem ex vivo brain tissue sections were illuminated using a high power (20mW) 830 nm near infrared diode laser, and subsequently spectra were gained in the region of 2000-200 cm-1 from a 10 second accumulation time. Ethical approval was gained for the examination of 18 individual donors exhibiting varying states of Alzheimer's disease, Huntingdon's disease and their corresponding age-matched healthy controls. Following on from previous preliminary studies, the Raman spectra were found to be highly reproducible, and when examined further, the spectra showed differences relating to the content and structure of the proteins in the individual brain samples, in particular, the beta-amyloid protein structure found in Alzheimer's disease patients. Principle components analysis further determined these protein structural changes, with Alzheimer's disease and Huntingdon's disease samples being defined from the healthy controls, and from each other.

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

2005-08-01

197

Multimodal, multiplex, Raman spectroscopy of alcohol in diffuse, fluorescent media  

E-print Network

Multimodal, multiplex, Raman spectroscopy of alcohol in diffuse, fluorescent media Scott T. Mc spectrometer to detect alcohol in a lipid tissue phantom solution. Keywords: Raman Spectroscopy, Tissue in solutions of a lipid tissue phantom. At high lipid concentrations, our instrument detects Raman signatures

Pitsianis, Nikos P.

198

Surface-sensitive polarized Raman spectroscopy of biological tissue  

E-print Network

Surface-sensitive polarized Raman spectroscopy of biological tissue Zachary J. Smith and Andrew J even confounding signals.1 Raman spectroscopy of such a layered me- dium will in general detect this method to Raman scattering in two two-layer models with a highly diffusing lower layer of glucose powder

Berger, Andrew J.

199

Detecting changes during pregnancy with Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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.

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

2010-02-01

200

Single bacteria identification by Raman spectroscopy.  

PubMed

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

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

2014-11-01

201

Single bacteria identification by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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. 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. 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.

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

2014-11-01

202

Searching for minicharged particles via birefringence, dichroism and Raman spectroscopy of the vacuum polarized by a high-intensity laser wave  

SciTech Connect

Absorption and dispersion of probe photons in the field of a high-intensity circularly polarized laser wave are investigated. The optical theorem is applied for determining the absorption coefficients in terms of the imaginary part of the vacuum polarization tensor. Compact expressions for the vacuum refraction indices and the photon absorption coefficients are obtained in various asymptotic regimes of interest. The outcomes of this analysis reveal that, far from the region relatively close to the threshold of the two-photon reaction, the birefringence and dichroism of the vacuum are small and, in some cases, strongly suppressed. On the contrary, in a vicinity of the region in which the photo-production of a pair occurs, these optical properties are manifest with lasers of moderate intensities. We take advantage of such a property in the search of minicharged particles by considering high-precision polarimetric experiments. In addition, Raman-like electromagnetic waves resulting from the inelastic part of the vacuum polarization tensor are suggested as an alternative form for finding exclusion limits on these hypothetical charge carriers. The envisaged parameters of upcoming high-intensity laser facilities are used for establishing upper bounds on the minicharged particles. -- Highlights: •Via dichroism and birefringence of the vacuum by a strong laser wave, minicharged particles can be probed. •The discovery potential is the highest in a vicinity of the first pair production threshold. •As alternative observable, Raman scattered waves are put forward.

Villalba-Chávez, S., E-mail: selymv@gmail.com; Müller, C., E-mail: c.mueller@tp1.uni-duesseldorf.de

2013-12-15

203

Raman spectroscopy in investigation of rheometric processes  

Microsoft Academic Search

Studies of application of Raman spectroscopy in measurement of important parameters of rheometric process, including profile of oil film thickness and composition of oil\\/paste system, were carried out. The films of silicone oil AK106 (Wacker) extracted from ceramic paste AlOOH were subjects of investigations presented in this paper. Boundary between oil film and extruded paste is not regular and ambiguous

Marcin Gnyba; Robert Bogdanowicz; Marcin Kozanecki

2005-01-01

204

Raman spectroscopy explores molecular structural signatures of hidden materials in depth: Universal Multiple Angle Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Non-invasive 3D imaging in materials and medical research involves methodologies such as X-ray imaging, MRI, fluorescence and optical coherence tomography, NIR absorption imaging, etc., providing global morphological/density/absorption changes of the hidden components. However, molecular information of such buried materials has been elusive. In this article we demonstrate observation of molecular structural information of materials hidden/buried in depth using Raman scattering. Typically, Raman spectroscopic observations are made at fixed collection angles, such as, 90°, 135°, and 180°, except in spatially offset Raman scattering (SORS) (only back scattering based collection of photons) and transmission techniques. Such specific collection angles restrict the observations of Raman signals either from or near the surface of the materials. Universal Multiple Angle Raman Spectroscopy (UMARS) presented here employs the principle of (a) penetration depth of photons and then diffuse propagation through non-absorbing media by multiple scattering and (b) detection of signals from all the observable angles.

Sil, Sanchita; Umapathy, Siva

2014-06-01

205

Raman spectroscopy explores molecular structural signatures of hidden materials in depth: Universal Multiple Angle Raman Spectroscopy  

PubMed Central

Non-invasive 3D imaging in materials and medical research involves methodologies such as X-ray imaging, MRI, fluorescence and optical coherence tomography, NIR absorption imaging, etc., providing global morphological/density/absorption changes of the hidden components. However, molecular information of such buried materials has been elusive. In this article we demonstrate observation of molecular structural information of materials hidden/buried in depth using Raman scattering. Typically, Raman spectroscopic observations are made at fixed collection angles, such as, 90°, 135°, and 180°, except in spatially offset Raman scattering (SORS) (only back scattering based collection of photons) and transmission techniques. Such specific collection angles restrict the observations of Raman signals either from or near the surface of the materials. Universal Multiple Angle Raman Spectroscopy (UMARS) presented here employs the principle of (a) penetration depth of photons and then diffuse propagation through non-absorbing media by multiple scattering and (b) detection of signals from all the observable angles. PMID:24930768

Sil, Sanchita; Umapathy, Siva

2014-01-01

206

Mineralogy of Meteorite Chelyabinsk as Determined by Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Using Raman spectroscopy, we have characterized the mineral phases of meteorite Chelyabinsk, fall 15 February 2013, Chelyabinsk, Russia. Raman spectra are shown for olivine, pyroxene, feldspar, magnetite, pyrrhotite, calcite and, possibly, parisite.

Voropaev, S. A.; Eliseev, A. A.; Petukhov, D. I.

2014-06-01

207

High average power diamond Raman laser.  

PubMed

We report a pulsed Raman laser at 1193 nm based on synthetic diamond crystals with a record output power of 24.5 W and a slope efficiency of 57%. We compared the performance of an anti-reflection coated crystal at normal incidence with a Brewster cut sample. Raman oscillation was achieved at both room temperature and under cryogenic operation at 77 K. Modeling of these experiments allowed us to confirm the value of Raman gain coefficient of diamond, which was found to be 13.5 ± 2.0 cm/GW for a pump wavelength of 1030 nm. PMID:21263631

Feve, Jean-Philippe M; Shortoff, Kevin E; Bohn, Matthew J; Brasseur, Jason K

2011-01-17

208

Laser pulses for coherent xuv Raman excitation  

E-print Network

We combine multi-channel electronic structure theory with quantum optimal control to derive Raman pulse sequences that coherently populate a valence excited state. For a neon atom, Raman target populations of up to 13% are obtained. Superpositions of the ground and valence Raman states with a controllable relative phase are found to be reachable with up to 4.5% population and phase control facilitated by the pump pulse carrier envelope phase. Our results open a route to creating core-hole excitations in molecules and aggregates that locally address specific atoms and represent the first step towards realization of multidimensional spectroscopy in the xuv and x-ray regimes.

Greenman, Loren; Whaley, K Birgitta

2014-01-01

209

In vivo Raman spectroscopy for breast cancer: diagnosis in animal model  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has been well established as a powerful method for studying biological tissues and diagnosing diseases. In this study we have developed a breast cancer animal model and collected in vivo Raman spectra of mammary glands of 27 Sprague-Dawley female rats treated with DMBA and 5 non-treated used as control group. A dispersive Raman spectrometer with a @785 nm laser excitation coupled a fiber optic probe and a CCD detector was used to obtain the spectra. The obtained in vivo transcutaneous Raman spectra have shown important differences between normal and abnormal tissues when acquired from one side to the other side of the lesion.

Bitar, R.; Martins, M. A.; Ribeiro, D.; Carvalho, C.; Santos, E. A. P.; Ramalho, L. N. Z.; Ramalho, F.; Martinho, H.; Martin, A. A.

2008-02-01

210

Characterization of the lithium surface by infrared and Raman spectroscopies  

NASA Astrophysics Data System (ADS)

The chemical composition of the pristine passivation layer formed on the surface of commercial lithium foils has been investigated by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and confocal Raman microspectrometry (CRM). Carbonates and hydroxides are easily detected by PM-IRRAS and on-line non-destructive analysis could be envisaged with this technique or even with the simpler IRRAS technique in dry atmosphere. On the other hand, local heating under laser irradiation is difficult to avoid in CRM. It transforms carbonate species into lithium acetylides of the Li 2C 2 type characterized by a ?C?C line at ca. 1845 cm -1. This might explain an unexpected Raman line observed at 1830-1850 cm -1 in previous literature studies of the lithium/electrolyte interface or of the carbon/electrolyte interface in lithium-ion batteries.

Naudin, C.; Bruneel, J. L.; Chami, M.; Desbat, B.; Grondin, J.; Lassègues, J. C.; Servant, L.

211

Diagnosing breast cancer by using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

212

Noise autocorrelation spectroscopy with coherent Raman scattering  

Microsoft Academic Search

Ultrafast lasers have become one of the most powerful tools in coherent\\u000anonlinear optical spectroscopy. Short pulses enable direct observation of fast\\u000amolecular dynamics, whereas broad spectral bandwidth offers ways of controlling\\u000anonlinear optical processes by means of quantum interferences. Special care is\\u000ausually taken to preserve the coherence of laser pulses as it determines the\\u000aaccuracy of a spectroscopic

Xiaoji G. Xu; Stanislav O. Konorov; John W. Hepburn; Valery Milner

2007-01-01

213

Cervical cancer detection based on serum sample Raman spectroscopy.  

PubMed

The use of Raman spectroscopy to analyze the biochemical composition of serum samples and hence distinguish between normal and cervical cancer serum samples was investigated. The serum samples were obtained from 19 patients who were clinically diagnosed with cervical cancer, 3 precancer, and 20 healthy volunteer controls. The imprint was put under an Olympus microscope, and around points were chosen for Raman measurement.All spectra were collected at a Horiba Jobin-Yvon LabRAM HR800 Raman Spectrometer with a laser of 830-nm wavelength and 17-mW power irradiation. Raw spectra were processed by carrying out baseline correction, smoothing, and normalization to remove noise, florescence, and shot noise and then analyzed using principal component analysis (PCA). The control serum spectrum showed the presence of higher amounts of carotenoids indicated by peaks at 1,002, 1,160, and 1,523 cm(-1)and intense peaks associated with protein components at 754, 853, 938, 1,002, 1,300-1,345, 1,447, 1,523, 1,550, 1,620, and 1,654 cm(-1). The Raman bands assigned to glutathione (446, 828, and 1,404 cm(-1)) and tryptophan (509, 1,208, 1,556, 1,603, and 1,620 cm(-1)) in cervical cancer were higher than those of control samples, suggesting that their presence may also play a role in cervical cancer. Furthermore, weak bands in the control samples attributed to tryptophan (545, 760, and 1,174 cm(-1)) and amide III (1,234-1,290 cm(-1)) seem to disappear and decrease in the cervical cancer samples, respectively. It is shown that the serum samples from patients with cervical cancer and from the control group can be discriminated with high sensitivity and specificity when the multivariate statistical methods of PCA is applied to Raman spectra. PCA allowed us to define the wavelength differences between the spectral bands of the control and cervical cancer groups by confirming that the main molecular differences among the control and cervical cancer samples were glutathione, tryptophan, ? carotene, and amide III. The preliminary results suggest that Raman spectroscopy could be a highly effective technique with a strong potential of support for current techniques as Papanicolaou smear by reducing the number of these tests; nevertheless, with the construction of a data library integrated with a large number of cervical cancer and control Raman spectra obtained from a wide range of healthy and cervical cancer population, Raman-PCA technique could be converted into a new technique for noninvasive real-time diagnosis of cervical cancer from serum samples. PMID:24197519

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

2014-05-01

214

Wavelength-scanned surface-enhanced Raman excitation spectroscopy.  

PubMed

A detailed wavelength-scanned surface-enhanced Raman excitation spectroscopy (WS SERES) study of benzenethiol adsorbed on Ag nanoparticle arrays, fabricated by nanosphere lithography (NSL), is presented. These NSL-derived Ag nanoparticle array surfaces are both structurally well-characterized and extremely uniform in size. The WS SERES spectra are correlated, both spatially and spectrally, with the corresponding localized surface plasmon resonance (LSPR) spectra of the nanoparticle arrays. The surface-enhanced Raman scattering (SERS) spectra were measured in two excitation wavelength ranges: (1) 425-505 nm, and (2) 610-800 nm, as well as with the 532-nm line from a solid-state diode-pumped laser. The WS SERES spectra have line shapes similar to those of the LSPR spectra. The maximum SERS enhancement factor is shown to occur for excitation wavelengths that are blue-shifted with respect to the LSPR lambda(max) of adsorbate-covered nanoparticle arrays. Three vibrational modes of benzenethiol (1575, 1081, and 1009 cm(-1)) are studied simultaneously on one substrate, and it is demonstrated that the smaller Raman shifted peak shows a maximum enhancement closer to the LSPR lambda(max) than that of a larger Raman shifted peak. This is in agreement with the predictions of the electromagnetic (EM) enhancement mechanism of SERS. Enhancement factors of up to approximately 10(8) are achieved, which is also in good agreement with our previous SERES studies. PMID:16852377

McFarland, Adam D; Young, Matthew A; Dieringer, Jon A; Van Duyne, Richard P

2005-06-01

215

Future directions for Fourier Transform Raman spectroscopy in industrial analysis  

NASA Astrophysics Data System (ADS)

FT Raman spectroscopy is now the most widely used method for overcoming fluorescence in Raman spectroscopy. Its main use is for extending the range and type of samples which are amenable to Raman spectroscopy. Over the last year or so much has been achieved using the method for solving industrial analytical problems. This article details some examples of the application of the method to such problems. It also highlights areas for future deveopment, in particular reaction monitoring and remote sampling. These are felt to be areas in which FT Raman spectroscopy can make a significant impact in the industrial world.

Williams, K. P. J.; Mason, S. M.

216

Ultraviolet surface-enhanced Raman spectroscopy using aluminum plasmonic gratings  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman scattering (SERS) has been widely studied both theoretically and experimentally for chemical and biological sensing, primarily in the visible and near-infrared wavelengths. Although in the ultraviolet (UV) plasmonic behavior is limited by metallic dampening, we have theoretically shown that SERS enhancement factors as large as 10^5 can be achieved when the laser is tuned to the plasmonic band edge of an Al metallic grating grown on a sapphire substrate. Using electron beam lithography, aluminum gratings were fabricated whose pitch (150-300 nm), slit widths (64 nm), and thickness (50 nm) were chosen to produce large enhancement factors at wavelengths in the UV. Analytes such as thiophenol were then deposited on the gratings, and UV-SERS spectroscopy was performed to measure the enhancement factors and compare with theoretical estimates. Enhancement factors were measured by comparing the strength of the Raman signal from the grating region with the strength of the Raman signal from adjacent regions without a grating. The dependence of the enhancement factor on laser wavelength relative to the plasmonic band edge for a given grating pitch was explored, as was the effect of using a tapered slit geometry that focuses the local field on the nanoscale.

Roberts, Adam T.; Butun, Serkan; Aydin, Koray; Everitt, Henry O.; Bloemer, Mark; D'Aguanno, Giuseppe; Mattiucci, Nadia

2013-03-01

217

In vivo lipidomics using single-cell Raman spectroscopy  

PubMed Central

We describe a method for direct, quantitative, in vivo lipid profiling of oil-producing microalgae using single-cell laser-trapping Raman spectroscopy. This approach is demonstrated in the quantitative determination of the degree of unsaturation and transition temperatures of constituent lipids within microalgae. These properties are important markers for determining engine compatibility and performance metrics of algal biodiesel. We show that these factors can be directly measured from a single living microalgal cell held in place with an optical trap while simultaneously collecting Raman data. Cellular response to different growth conditions is monitored in real time. Our approach circumvents the need for lipid extraction and analysis that is both slow and invasive. Furthermore, this technique yields real-time chemical information in a label-free manner, thus eliminating the limitations of impermeability, toxicity, and specificity of the fluorescent probes common in currently used protocols. Although the single-cell Raman spectroscopy demonstrated here is focused on the study of the microalgal lipids with biofuel applications, the analytical capability and quantitation algorithms demonstrated are applicable to many different organisms and should prove useful for a diverse range of applications in lipidomics. PMID:21310969

Wu, Huawen; Volponi, Joanne V.; Oliver, Ann E.; Parikh, Atul N.; Simmons, Blake A.; Singh, Seema

2011-01-01

218

Raman Spectroscopy and instrumentation for monitoring soil carbon systems.  

SciTech Connect

This work describes developments in the application of Raman scattering and surface-enhanced Raman scattering (SERS) towards the assessment/characterization of carbon in soil. In the past, the nonspecific total carbon mass content of soil samples has generally been determined through mass loss techniques and elemental analysis. However, because of the concern over CO{sub 2} buildup in the atmosphere and its possible role in the ''Greenhouse Effect,'' there is a need for better-defined models of global cycling of carbon. As a means towards this end, there is a need to know more about the structure and functionality of organic materials in soil. Raman spectroscopy may therefore prove to be an exceptional tool in soil carbon analysis. Based on vibrational transitions of irradiated molecules, it provides structural information that is often suitable for sample identification. Furthermore, Raman scattering yields very fine spectral features which offer the potential for multicomponent sample analysis with minimal or no sample pretreatment. Although the intensity of Raman scattering is generally extremely low, the surface-enhanced Raman scattering (SERS) effect can greatly enhance Raman signals (10{sup 6}-10{sup 8} range) through the adsorption of compounds on specially roughened metal surfaces. In our laboratory, we have investigated copper, gold and silver as possible substrate metals in the fabrication of SERS substrates. These substrates have included metal-coated microparticles, metal island films, and redox-roughened metal foils. We have evaluated several laser excitation sources spanning the 515-785 nm range for both Raman and SERS analysis. For this particular study, we have selected fulvic and humic acids as models for establishing the feasibility of using Raman and SERS in soil carbon analysis. Our studies thus far have demonstrated that copper substrates perform best in the SERS detection of humic and fulvic acids, particularly when coupled to electrochemical processes that enhance adsorption of specific compounds. This effect not only yields a stronger signal, but can also impart selectivity in the analysis of complex samples such as soil.

Stokes, D.L.

2003-12-08

219

Raman laser with controllable suppression of parasitics  

DOEpatents

Method and apparatus for switching energy out of a Raman laser optical cavity. Coherent radiation at both the pump and first Stokes wave frequencies are introduced into the optical cavity from the same direction, and a second Stokes wave is utilized to switch the energy out of the cavity.

George, E. Victor (Livermore, CA)

1986-01-01

220

Characterization of Thalidomide using Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

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

Cipriani, Penelope; Smith, Candace Y.

2008-02-01

221

AFM CHARACTERIZATION OF RAMAN LASER INDUCED DAMAGE ON CDZNTECRYSTAL SURFACES  

SciTech Connect

High quality CdZnTe (or CZT) crystals have the potential for use in room temperature gamma-ray and X-ray spectrometers. Over the last decade, the methods for growing high quality CZT have improved the quality of the produced crystals however there are material features that can influence the performance of these materials as radiation detectors. The presence of structural heterogeneities within the crystals, such as twinning, pipes, grain boundaries (polycrystallinity), and secondary phases (SPs) can have an impact on the detector performance. There is considerable need for reliable and reproducible characterization methods for the measurement of crystal quality. With improvements in material characterization and synthesis, these crystals may become suitable for widespread use in gamma radiation detection. Characterization techniques currently utilized to test for quality and/or to predict performance of the crystal as a gamma-ray detector include infrared (IR) transmission imaging, synchrotron X-ray topography, photoluminescence spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM) and Raman spectroscopy. In some cases, damage caused by characterization methods can have deleterious effects on the crystal performance. The availability of non-destructive analysis techniques is essential to validate a crystal's quality and its ability to be used for either qualitative or quantitative gamma-ray or X-ray detection. The work presented herein discusses the damage that occurs during characterization of the CZT surface by a laser during Raman spectroscopy, even at minimal laser powers. Previous Raman studies have shown that the localized annealing from tightly focused, low powered lasers results in areas of higher Te concentration on the CZT surface. This type of laser damage on the surface resulted in decreased detector performance which was most likely due to increased leakage current caused by areas of higher Te concentration. In this study, AFM was used to characterize the extent of damage to the CZT crystal surface following exposure to a Raman laser. AFM data reveal localized surface damage and increased conductivity in the areas exposed to the Raman laser beam.

Teague, L.; Duff, M.

2008-10-07

222

Characterization and identification of contraband using UV resonant Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

1997-02-01

223

Coherent anti-Stokes Raman spectroscopy temperature measurements in an internal combustion engine  

Microsoft Academic Search

Part of a project to investigate the physics and chemistry of alternative fuels in internal combustion engines is reported. Coherent anti-Stokes Raman spectroscopy (CARS) is used to probe the fuel-air mixture in the cylinder of a Richardo E6 variable compression ratio research engine. The laser system comprises a passively Q- switched single-longitudinal-mode frequency-doubled Nd:YAG laser and a broadband dye laser,

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

1994-01-01

224

Applications of Raman Spectroscopy in Material Science: Material Characterization and Temperature Measurements  

E-print Network

Applications of Raman Spectroscopy in Material Science: Material Characterization and Temperature University Raman spectroscopy is a powerful tool for characterizing materials and measuring temperatures and robust characterization. We applied Raman spectroscopy to characterize CVD synthesized MoS2

Mellor-Crummey, John

225

UTI diagnosis and antibiogram using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2009-07-01

226

Teaching Raman Spectroscopy in Both the Undergraduate Classroom and the Laboratory with a Portable Raman Instrument  

Microsoft Academic Search

We have evaluated a small portable Raman instrument on loan from B&W Tek, Inc., and have determined that it can successfully be used in the classroom both as a visual aid for teaching the fundamentals of Raman spectroscopy and for a variety of undergraduate experiments as a normal component of an instrumental analysis class. Having portable Raman instrumentation would allow

Evan D. Hudspeth; Danielle Cleveland; Kathleen L. Batchler; Phuong A. Nguyen; Tracey L. Feaser; Lauren E. Quattrochi; Jesse Morenz; Shrimati A. Balram; Robert G. Michel; Jack Zhou; Daniel Lombardi

2006-01-01

227

J. raman Spectroscopy 38 [5] 504-514. Nanomechanics of single keratin fibres: A Raman study of the  

E-print Network

J. raman Spectroscopy 38 [5] 504-514. Nanomechanics of single keratin fibres: A Raman study-chain distances during the strain to be distinguished. The combination of micro-Raman spectroscopy and a allows Colomban hal-00152016,version1-6Jun2007 Author manuscript, published in "Journal of Raman Spectroscopy 38

228

Femtosecond stimulated Raman spectroscopy of ultrafast biophysical reaction dynamics  

NASA Astrophysics Data System (ADS)

I have developed the technique of femtosecond stimulated Raman spectroscopy (FSRS), which enables the rapid acquisition of vibrational spectra with <100-fs time-resolution and <15-cm-1 frequency-resolution. FSRS uses three laser pulses: (1) a femtosecond visible actinic pump that initiates the photochemistry, (2) a narrow bandwidth picosecond Raman pump that provides the energy for amplification of the probe, and (3) a femtosecond continuum probe that is amplified at Raman resonances shifted from the Raman pump. FSRS has the ability to collect Raman spectra and depolarization ratios with only seconds of data averaging and negligible fluorescence interference. The capabilities of FSRS are explored through studies of the polyene beta-carotene. My initial experiments used picosecond time-resolved Stokes and anti-Stokes spontaneous resonance Raman spectroscopy to determine that vibrational relaxation in the S1 (2Ag-) electronic state is nearly complete within 2 ps and to quantify the intramolecular vibrational energy redistribution (IVR) processes in S0. FSRS studies on beta-carotene revealed that following optical excitation to S2 (1Bu +) the molecule relaxes to S1 in 160 fs where it undergoes rapid two-step IVR with 200- and 450-fs time constants. In later work, the FSRS spectrum of S2 beta-carotene was observed, which consists of three intense and broad bands at ˜1100, 1300 and 1650 cm-1 that exhibit kinetics matching the decay of the S2 near-infrared absorption. These data show that there is no additional intermediate 1B u- electronic state involved in the relaxation pathway of beta-carotene. FSRS was also used to study the photoisomerization dynamics in bacteriorhodopsin (bR). Spectra obtained during bR's excited state lifetime exhibit dispersive lineshapes at the ground-state frequencies that decay in 250 fs and are attributed to a nonlinear emission process. This relaxation is significantly faster than the decay of the stimulated emission (˜500 fs), indicating that the excited population moves away from the ground-state geometry in 250 fs. Spectral changes between 1.5 to 100 ps reveal that a significant fraction of the isomerization occurs on the ground state photoproduct surface. The many benefits FSRS will make it a valuable tool for vibrational spectroscopy of reaction dynamics in ultrafast photochemical and photophysical processes.

McCamant, David William

2004-12-01

229

Raman spectroscopy of gases with a Fourier transform spectrometer: the spectrum of D2  

Microsoft Academic Search

A high-resolution Fourier transform spectrometer (FTS) has been used to record spontaneous incoherent laser Raman spectra of gases. The resolution, sensitivity, calibration accuracy, and spectral coverage achieved in these spectra demonstrate the viability of the FTS for Raman spectroscopy. Measurements from a spectrum of D2 containing both v = 0-0 and v = 1-0 transitions were fitted to the Dunham

Donald E. Jennings; A. Weber; J. W. Brault

1986-01-01

230

Calcium oxalate in lichen biodeterioration studied using FT-Raman spectroscopy  

Microsoft Academic Search

The biodeterioration of diverse natural and man-made substrata by Caloplaca aurantia, Lecanora muralis and Acarospora oxytoma has been studied using FT-Raman spectroscopy with 1064 nm laser excitation. Each of the three lichen species produce relatively large amounts of calcium oxalate in encrustations at the thallus—substratum interface during the biodeterioration process; the Raman spectroscopic technique is capable of identifying non-destructively the

H. G. M. Edwards; N. C. Russell; M. R. D. Seaward

1997-01-01

231

Resonant Raman spectroscopy of twisted multilayer graphene  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

232

Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters  

PubMed Central

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

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

2013-01-01

233

Saturation spectroscopy of coherent raman scattering in molecular gases  

Microsoft Academic Search

We present the theory of two-photon Raman saturation of a two-level Raman transition studied by an independent CARS process. The main goal here is to probe the saturated homogeneous Raman line shape. It is shown that there appears a saturation dip with a width determined by the relaxation timeT1. In the case of Doppler-broadened line the coherent Raman saturation spectroscopy

V. N. Zadkov; N. I. Koroteev; M. V. Rychov; A. B. Feodorov

1984-01-01

234

ExoMars Raman laser spectrometer for Exomars  

NASA Astrophysics Data System (ADS)

The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. ExoMars 2018 main Scientific objective is "Searching for evidence of past and present life on Mars". Raman Spectroscopy is used to analyze the vibrational modes of a substance either in the solid, liquid or gas state. It relies on the inelastic scattering (Raman Scattering) of monochromatic light produced by atoms and molecules. The radiation-matter interaction results in the energy of the exciting photons to be shifted up or down. The shift in energy appears as a spectral distribution and therefore provides an unique fingerprint by which the substances can be identified and structurally analyzed. The RLS is being developed by an European Consortium composed by Spanish, French, German and UK partners. It will perform Raman spectroscopy on crushed powdered samples inside the Rover's Analytical Laboratory Drawer. Instrument performances are being evaluated by means of simulation tools and development of an instrument prototype.

Rull, F.; Sansano, A.; Díaz, E.; Canora, C. P.; Moral, A. G.; Tato, C.; Colombo, M.; Belenguer, T.; Fernández, M.; Manfredi, J. A. R.; Canchal, R.; Dávila, B.; Jiménez, A.; Gallego, P.; Ibarmia, S.; Prieto, J. A. R.; Santiago, A.; Pla, J.; Ramos, G.; Díaz, C.; González, C.

2011-10-01

235

Stimulated Raman microscopy without ultrafast lasers  

NASA Astrophysics Data System (ADS)

Stimulated Raman scattering (SRS) microscopy is a powerful tool for chemically-sensitive non-invasive optical imaging. However, the short-pulse laser sources, which are currently being employed for this imaging technique, are still expensive and require substantial maintenance to provide temporal and spectral overlap. SRS imaging, which utilizes cw laser sources, has a major advantage over pulsed lasers, as it eliminates the possibility of cell damage due to exposure to high-intensity light radiation, while substantially reducing the cost and complexity of the set-up and keeping a sub-cellular spatial resolution. As a proof-of-principle, we demonstrate microscopic imaging of dimethyl sulfoxide using two independent, commonly used and inexpensive lasers: a diode-pumped, intracavity doubled 532 nm laser and a He-Ne laser operating at 633 nm. In our proof-of-principle experience, dimethyl sulfoxide acts as a contrast agent providing Raman scattering signal. The 532 nm and 633 nm lasers act as excitation and probe sources, respectively [1].

Meng, Zhaokai; Petrov, Georgi I.; Yakovlev, Vladislav V.

2013-02-01

236

Highly efficient Raman distributed feedback fibre lasers.  

PubMed

We demonstrate highly efficient Raman distributed feedback (DFB) fibre lasers for the first time with up to 1.6 W of continuous wave (CW) output power. The DFB Bragg gratings are written directly into two types of commercially available passive germano-silica fibres. Two lasers of 30 cm length are pumped with up to 15 W of CW power at 1068 nm. The threshold power is ~2 W for a Raman-DFB (R-DFB) laser written in standard low-NA fibre, and only ~1 W for a laser written in a high-NA fibre, both of which oscillate in a narrow linewidth of <0.01 nm at ~1117 nm and ~1109 nm, respectively. The slope efficiencies are ~74% and ~93% with respect to absorbed pump power in the low-NA fibre and high-NA fibre respectively. Such high conversion efficiency suggests that very little energy is lost in the form of heat through inefficient energy transfer. Our results are supported by numerical simulations, and furthermore open up for the possibility of having narrow linewidth all-fibre laser sources in wavelength bands not traditionally covered by rare-earth doped silica fibres. Simulations also imply that this technology has the potential to produce even shorter R-DFB laser devices at the centimetre-level and with mW-level thresholds, if Bragg gratings formed in fibre materials with higher intrinsic Raman gain coefficient than silica are used. These materials include for example tellurite or chalcogenide glasses. Using glasses like these would also open up the possibility of having narrow linewidth fibre sources with DFB laser oscillating much further into the IR than what currently is possible with rare-earth doped silica glasses. PMID:22418313

Shi, Jindan; Alam, Shaif-ul; Ibsen, Morten

2012-02-27

237

Combined coherent anti-Stokes Raman spectroscopy and linear Raman spectroscopy for simultaneous temperature and multiple species measurements  

Microsoft Academic Search

The simultaneous application of pure rotational coherent anti-Stokes Raman spectroscopy (CARS) and vibrational linear Raman spectroscopy (LRS) for the measurement of temperature and species concentrations in combustion systems is demonstrated. In addition to the standard rotational CARS experimental setup, only one detection system (spectrometer and intensified CCD camera) for the collection of the LRS signals was applied. The emission of

Markus C. Weikl; Frank Beyrau; Johannes Kiefer; Thomas Seeger; Alfred Leipertz

2006-01-01

238

REMOTE RAMAN SPECTROSCOPY OF VARIOUS MIXED AND COMPOSITE MINERAL PHASES AT 7.2 m DISTANCE  

NASA Technical Reports Server (NTRS)

Remote Raman [e.g.,1-5] and micro-Raman spectroscopy [e.g., 6-10] are being evaluated on geological samples for their potential applications on Mars rover or lander. The Raman lines of minerals are sharp and distinct. The Raman finger-prints of minerals do not shift appreciably but remain distinct even in sub-micron grains and, therefore, can be used for mineral identification in fine-grained rocks [e.g., 4,7]. In this work we have evaluated the capability of a directly coupled remote Raman system (co-axial configuration) for distinguishing the mineralogy of multiple crystals in the exciting laser beam. We have measured the Raman spectra of minerals in the near vicinity of each other and excited with a laser beam (e.g. -quartz (Qz) and K-feldspar (Feld) plates, each 5 mm thick). The spectra of composite transparent mineral plates of 5 mm thickness of -quartz and gypsum over calcite crystal were measured with the composite samples perpendicular to the exciting laser beam. The measurements of remote Raman spectra of various bulk minerals, and mixed and composite minerals with our portable UH remote Raman system were carried out at the Langley Research Center in a fully illuminated laboratory.

Sharma, S. K.; Misra, A. K.; Ismail, Syed; Singh, U. N.

2006-01-01

239

Laser biomodulation in bone implants: a Raman spectral study  

NASA Astrophysics Data System (ADS)

Healing is important for the success of the insertion of implants and for treating traumatic or pathologic injuries of the bone. Lasertherapy has been suggested as a mean of improving bone healing. Near infrared Raman spectroscopy was used to assess the amount of both inorganic and organic components of irradiated and control bone around dental implants inserted in to the tibia. Fourteen rabbits received a titanium implant on the tibia; eight of them were irradiated with ?830nm laser (Thera Lase, DMC, Sao Carlos, SP, Brazil, 21.5 J/cm2, 10mW, spot size 0.60mm) and six acted as controls. The animals were sacrificed 15, 30 and 45 days after the surgery, and specimens were prepared for Raman spectroscopy, which was collected at every four points from each three thirds of the bone around the implants. The results showed significant differences in the concentration of inorganic components in irradiated specimens between 15 and 30days (p < 0.05), 15 and 45 (p < 0.01); between irradiated and controls 30 and 45 days after surgery (p <0.01). Concentration of organic components was also significantly different between irradiated and controls in periods of 30 to 45 days after surgery. It is concluded that LLLT does improve bone healing and Raman Spectroscopy can safely assess this.

Barbosa Lopes, Cibelle; Sathaiah, Sokki; Barbosa Pinheiro, Antonio L.; Duarte, Janaina; Martins, Maria C.

2003-06-01

240

Laser biomodulation in bone implants: a Raman spectral study  

NASA Astrophysics Data System (ADS)

Healing is important for the success of the insertion of implants and for treating traumatic or pathologic injuries of the bone. Lasertherapy has been suggested as a mean of improving bone healing. Raman spectroscopy was used to assess the amount of both inorganic and organic components of irradiated and non-irradiated bone around dental implants inserted in to the tibia. Fourteen rabbits received a titanium implant on the tibia, eight of them were irradiated with 830nm laser and six acted as controls. The animals were sacrificed 15, 30 and 45 days after the surgery, and specimens were prepared for Raman spectroscopy, which was collected at every four points from each three thirds of the bone around the implants. The results showed significant differences in the concentration of inorganic components in irradiated specimens between 15 and 30days, 15 and 45; between irradiated and controls 30 and 45 days after surgery. Concentration of organic components was also significantly different between irradiated and controls in periods of 30 to 45 days after surgery. It is concluded that LLLT does improve bone healing and this can be safely assessed by Raman Spectroscopy.

Lopes, Cibelle; Sathaiah, Sokki; Pinheiro, Antonio L. B.; Duarte, Janaina; Martin, Airton A.; Cunha, Vicente P. P.; Pacheco, Marcos T. T.

2002-03-01

241

[Rapid identification of potato cultivars using NIR-excited fluorescence and Raman spectroscopy].  

PubMed

Potato is one of the most important food in the world. Rapid and noninvasive identification of potato cultivars plays a important role in the better use of varieties. In this study, The identification ability of optical spectroscopy techniques, including near-infrared (NIR) Raman spectroscopy and NIR fluorescence spectroscopy, for invasive detection of potato cultivars was evaluated. A rapid NIR Raman spectroscopy system was applied to measure the composite Raman and NIR fluorescence spectroscopy of 3 different species of potatoes (98 samples in total) under 785 nm laser light excitation. Then pure Raman and NIR fluorescence spectroscopy were abstracted from the composite spectroscopy, respectively. At last, the partial least squares-discriminant analysis (PLS-DA) was utilized to analyze and classify Raman spectra of 3 different types of potatoes. All the samples were divided into two sets at random: the calibration set (74samples) and prediction set (24 samples), the model was validated using a leave-one-out, cross-validation method. The results showed that both the NIR-excited fluorescence spectra and pure Raman spectra could be used to identify three cultivars of potatoes. The fluorescence spectrum could distinguish the Favorita variety well (sensitivity: 1, specificity: 0.86 and accuracy: 0.92), but the result for Diamant (sensitivity: 0.75, specificity: 0.75 and accuracy: 0. 75) and Granola (sensitivity: 0.16, specificity: 0.89 and accuracy: 0.71) cultivars identification were a bit poorer. We demonstrated that Raman spectroscopy uncovered the main biochemical compositions contained in potato species, and provided a better classification sensitivity, specificity and accuracy (sensitivity: 1, specificity: 1 and accuracy: 1 for all 3 potato cultivars identification) among the three types of potatoes as compared to fluorescence spectroscopy. PMID:25208390

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

2014-03-01

242

Measurement of clathrate hydrates via Raman spectroscopy  

USGS Publications Warehouse

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

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

1997-01-01

243

Au-coated ZnO nanostructures for surface enhanced Raman spectroscopy applications  

SciTech Connect

Thin ZnO nanostructured films were produced by pulsed laser deposition (PLD) for surface enhanced Raman spectroscopy (SERS) studies. The experimental conditions used for preparation of the samples were chosen to obtain different types of ZnO nanostructures. The Raman spectra of rhodamine 6G (R6G) were measured at an excitation wavelength of 785 nm after coating the ZnO nanostructures with a thin Au layer. The influence of the surface morphology on the Raman signal obtained from the samples was investigated. High SERS signal enhancement was observed from all Au-coated ZnO nanostructures.

Dikovska, A O; Nedyalkov, N N; Imamova, S E; Atanasova, G B; Atanasov, P A

2012-03-31

244

Raman spectroscopy of human saliva for acute myocardial infarction detection  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

245

Raman spectroscopy for optical diagnosis of laryngeal cancer  

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

246

A combined remote Raman and LIBS instrument for characterizing minerals with 532 nm laser excitation.  

PubMed

The authors have developed an integrated remote Raman and laser-induced breakdown spectroscopy (LIBS) system for measuring both the Raman and LIBS spectra of minerals with a single 532 nm laser line of 35 mJ/pulse and 20 Hz. The instrument has been used for analyzing both Raman and LIBS spectra of carbonates, sulfates, hydrous and anhydrous silicates, and iron oxide minerals in air. These experiments demonstrate that by focusing a frequency-doubled 532 nm Nd:YAG pulsed laser beam with a 10x beam expander to a 529-microm diameter spot on a mineral surface located at 9 m, it is possible to measure simultaneously both the remote Raman and LIBS spectra of calcite, gypsum and olivine by adjusting the laser power electronically. The spectra of calcite, gypsum, and olivine contain fingerprint Raman lines; however, it was not possible to measure the remote Raman spectra of magnetite and hematite at 9 m because of strong absorption of 532 nm laser radiation and low intensities of Raman lines from these minerals. The remote LIBS spectra of both magnetite and hematite contain common iron emission lines but show difference in the minor amount of Li present in these two minerals. Remote Raman and LIBS spectra of a number of carbonates, sulfates, feldspars and phyllosilicates at a distance of 9 m were measured with a 532-nm laser operating at 35 mJ/pulse and by changing photon flux density at the sample by varying the spot diameter from 10 mm for Raman to 530 microm for LIBS measurements. The complementary nature of these spectra is highlighted and discussed. The combined Raman and LIBS system can also be re-configured to perform micro-Raman and micro-LIBS analyses, which have applications in trace/residue analysis and analysis of very small samples in the nano-gram range. PMID:19084470

Sharma, Shiv K; Misra, Anupam K; Lucey, Paul G; Lentz, Rachel C F

2009-08-01

247

A combined remote Raman and LIBS instrument for characterizing minerals with 532 nm laser excitation  

NASA Astrophysics Data System (ADS)

The authors have developed an integrated remote Raman and laser-induced breakdown spectroscopy (LIBS) system for measuring both the Raman and LIBS spectra of minerals with a single 532 nm laser line of 35 mJ/pulse and 20 Hz. The instrument has been used for analyzing both Raman and LIBS spectra of carbonates, sulfates, hydrous and anhydrous silicates, and iron oxide minerals in air. These experiments demonstrate that by focusing a frequency-doubled 532 nm Nd:YAG pulsed laser beam with a 10× beam expander to a 529-?m diameter spot on a mineral surface located at 9 m, it is possible to measure simultaneously both the remote Raman and LIBS spectra of calcite, gypsum and olivine by adjusting the laser power electronically. The spectra of calcite, gypsum, and olivine contain fingerprint Raman lines; however, it was not possible to measure the remote Raman spectra of magnetite and hematite at 9 m because of strong absorption of 532 nm laser radiation and low intensities of Raman lines from these minerals. The remote LIBS spectra of both magnetite and hematite contain common iron emission lines but show difference in the minor amount of Li present in these two minerals. Remote Raman and LIBS spectra of a number of carbonates, sulfates, feldspars and phyllosilicates at a distance of 9 m were measured with a 532-nm laser operating at 35 mJ/pulse and by changing photon flux density at the sample by varying the spot diameter from 10 mm for Raman to 530 ?m for LIBS measurements. The complementary nature of these spectra is highlighted and discussed. The combined Raman and LIBS system can also be re-configured to perform micro-Raman and micro-LIBS analyses, which have applications in trace/residue analysis and analysis of very small samples in the nano-gram range.

Sharma, Shiv K.; Misra, Anupam K.; Lucey, Paul G.; Lentz, Rachel C. F.

2009-08-01

248

ExoMars Raman laser spectrometer breadboard overview  

NASA Astrophysics Data System (ADS)

The Raman Laser Spectrometer (RLS) is one of the Pasteur Payload instruments, within the ESA's Aurora Exploration Programme, ExoMars mission. The RLS Instrument will perform Raman spectroscopy on crushed powdered samples deposited on a small container after crushing the cores obtained by the Rover's drill system. In response to ESA requirements for delta-PDR to be held in mid 2012, an instrument BB programme has been developed, by RLS Assembly Integration and Verification (AIV) Team to achieve the Technology Readiness level 5 (TRL5), during last 2010 and whole 2011. Currently RLS instrument is being developed pending its CoDR (Conceptual Design Revision) with ESA, in October 2011. It is planned to have a fully operative breadboard, conformed from different unit and sub-units breadboards that would demonstrate the end-to-end performance of the flight representative units by 2011 Q4.

Díaz, E.; Moral, A. G.; Canora, C. P.; Ramos, G.; Barcos, O.; Prieto, J. A. R.; Hutchinson, I. B.; Ingley, R.; Colombo, M.; Canchal, R.; Dávila, B.; Manfredi, J. A. R.; Jiménez, A.; Gallego, P.; Pla, J.; Margoillés, R.; Rull, F.; Sansano, A.; López, G.; Catalá, A.; Tato, C.

2011-10-01

249

From Femtosecond Dynamics to Breast Cancer Diagnosis by Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

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

Abramczyk, H.; Placek, I.; Bro?ek-P?uska, B.; Kurczewski, K.; Morawiec, Z.; Tazbir, M.

2007-12-01

250

From Femtosecond Dynamics to Breast Cancer Diagnosis by Raman Spectroscopy  

SciTech Connect

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

Abramczyk, H. [Institute of Applied Radiation Chemistry, Laboratory of Laser Molecular Spectroscopy, Technical University of Lodz, Faculty of Chemistry, 93-590 Lodz, Wroblewskiego 15 (Poland); Max-Born-Institute, Max-Born-Str. 2A, 12489 Berlin (Germany); Placek, I.; Brozek-Pluska, B.; Kurczewski, K. [Institute of Applied Radiation Chemistry, Laboratory of Laser Molecular Spectroscopy, Technical University of Lodz, Faculty of Chemistry, 93-590 Lodz, Wroblewskiego 15 (Poland); Morawiec, Z.; Tazbir, M. [Kopernik Hospital, Oncology Ward, Lodz (Poland)

2007-12-26

251

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 713719 (1998)  

E-print Network

of soluble mercury(II)­pyridine complexes in the interphase. Characteristic Raman bands of these complexes of mercury(II)­pyridine complexes [of general formula where 1 � n � 4] was produced in the interphase. 1998, such as platinum and nickel,9 using these new Raman systems. Mercury is the most studied working electrode

Brolo, Alexandre G.

252

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2005; 36: 629634  

E-print Network

; Accepted 3 January 2005 Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman scattering (SERRS) from oxazine 720 (oxa) dye adsorbed on scratched gold films are reported. The SERS of SERS applications in chemical sensing and optical switching. Moreover, we also show

Brolo, Alexandre G.

253

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

SciTech Connect

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

Ooi, C. H. Raymond [School of Engineering, Monash University, Jalan Lagoon Selatan, Bandar Sunway, 46150 Selangor DarulEhsan, Malaysia and Department of Physics, Korea University, Anam-dong, Seongbuk-gu, Seoul, 136-713 (Korea, Republic of)

2009-07-10

254

The many facets of Raman spectroscopy for biomedical analysis.  

PubMed

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

Krafft, Christoph; Popp, Jürgen

2015-01-01

255

Ultrafast Laser-Based Spectroscopy and Sensing: Applications in LIBS, CARS, and THz Spectroscopy  

PubMed Central

Ultrafast pulsed lasers find application in a range of spectroscopy and sensing techniques including laser induced breakdown spectroscopy (LIBS), coherent Raman spectroscopy, and terahertz (THz) spectroscopy. Whether based on absorption or emission processes, the characteristics of these techniques are heavily influenced by the use of ultrafast pulses in the signal generation process. Depending on the energy of the pulses used, the essential laser interaction process can primarily involve lattice vibrations, molecular rotations, or a combination of excited states produced by laser heating. While some of these techniques are currently confined to sensing at close ranges, others can be implemented for remote spectroscopic sensing owing principally to the laser pulse duration. We present a review of ultrafast laser-based spectroscopy techniques and discuss the use of these techniques to current and potential chemical and environmental sensing applications. PMID:22399883

Leahy-Hoppa, Megan R.; Miragliotta, Joseph; Osiander, Robert; Burnett, Jennifer; Dikmelik, Yamac; McEnnis, Caroline; Spicer, James B.

2010-01-01

256

Periodontitis diagnostics using resonance Raman spectroscopy on saliva  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

257

Investigation of Model Cell Membranes with Raman Spectroscopy: A Biochemistry Laboratory Experiment  

NASA Astrophysics Data System (ADS)

New developments that extend the usefulness of Raman spectroscopy for the investigation of biological systems are described. One of these methods, excitation with a near-infrared laser at 1064 nm and detection with a Fourier transform infrared spectrometer, is applied to the investigation of temperature profiles of dispersions of phospholipids in water. These dispersions are models of biomembranes. This experiment for the undergraduate biochemisty laboratory gives students experience applying vibrational spectroscopy to the investigation of the molecular properties of biomembranes. The basis of the Raman effect is reviewed.

Craig, Norman C.; Fuchsman, William H.; Lacuesta, Nanette N.

2003-11-01

258

Chromosomal analysis and identification based on optical tweezers and Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The ability to identify specific chromosomes with certainty has been established by the development of several cytogenetic techniques based on staining. Here, we report the use of a new optical technique, laser tweezers and Raman spectroscopy (LTRS), to capture and manipulate chromosomes in order to obtain their spectral patterns for molecular analysis without the need for staining. The purpose of this study was to obtain Raman spectroscopy patterns for chromosomes number 1, 2, and 3 and to test if the Raman spectroscopy pattern could be used to distinguish these three chromosomes. In our experiment, optical tweezers were used to capture the individual chromosomes and the Raman spectral patterns were collected for the trapped chromosomes. Then, the captured chromosome was manipulated with the optical tweezers and moved to another chamber through a micro - channel, in which the chromosomes were G banded for positive identification as chromosome number 1, 2, or 3. Generalized discriminate analysis (GDA) was used to compare the Raman signatures. This analysis revealed that chromosomes 1, 2, and 3 could be distinguished and identified based on their Raman spectra. Development of this approach will lead to more rapid automatic methods for chromosome analysis and identification without the use of prior staining. Moreover, the Raman spectral patterns may lend themselves to more detailed analysis of chromosomal structure than is currently available with standard staining protocols. Such analysis may some day be useful for rapid, automated screening and diagnosis for certain cancers.

Ojeda, Jenifer F.; Xie, Changan; Li, Yong-Qing; Bertrand, Fred E.; Wiley, John; McConnell, Thomas J.

2006-06-01

259

Visible and UV coherent Raman spectroscopy of dipicolinic acid  

PubMed Central

We use time-resolved coherent Raman spectroscopy to obtain molecule-specific signals from dipicolinic acid (DPA), which is a marker molecule for bacterial spores. We use femtosecond laser pulses in both visible and UV spectral regions and compare experimental results with theoretical predictions. By exciting vibrational coherence on more than one mode simultaneously, we observe a quantum beat signal that can be used to extract the parameters of molecular motion in DPA. The signal is enhanced when an UV probe pulse is used, because its frequency is near-resonant to the first excited electronic state of the molecule. The capability for unambiguous identification of DPA molecules will lead to a technique for real-time detection of spores. PMID:16217021

Pestov, Dmitry; Zhi, Miaochan; Sariyanni, Zoe-Elizabeth; Kalugin, Nikolai G.; Kolomenskii, Alexandre A.; Murawski, Robert; Paulus, Gerhard G.; Sautenkov, Vladimir A.; Schuessler, Hans; Sokolov, Alexei V.; Welch, George R.; Rostovtsev, Yuri V.; Siebert, Torsten; Akimov, Denis A.; Graefe, Stefanie; Kiefer, Wolfgang; Scully, Marlan O.

2005-01-01

260

Sensitivity of Raman spectroscopy to normal patient variability  

NASA Astrophysics Data System (ADS)

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

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

2011-11-01

261

Sensitivity of Raman spectroscopy to normal patient variability  

PubMed Central

Many groups have used Raman spectroscopy for diagnosing cervical dysplasia; however, there have been few studies looking at the effect of normal physiological variations on Raman spectra. We assess four patient variables that may affect normal Raman spectra: Race/ethnicity, body mass index (BMI), parity, and socioeconomic status. Raman spectra were acquired from a diverse population of 75 patients undergoing routine screening for cervical dysplasia. Classification of Raman spectra from patients with a normal cervix is performed using sparse multinomial logistic regression (SMLR) to determine if any of these variables has a significant effect. Results suggest that BMI and parity have the greatest impact, whereas race/ethnicity and socioeconomic status have a limited effect. Incorporating BMI and obstetric history into classification algorithms may increase sensitivity and specificity rates of disease classification using Raman spectroscopy. Studies are underway to assess the effect of these variables on disease. PMID:22112136

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

2011-01-01

262

In situ visible Raman spectroscopic study of phase change in LiCoO 2 film by laser irradiation  

Microsoft Academic Search

A phase change in LiCoO2\\/Co films in a spot of 1 ?m diameter has been investigated under ambient conditions using 514.5 nm radiation by laser Raman spectroscopy. Laser irradiation resulted in a remarkable phase change of the film from hexagonal to cubic spinel, forming a lithium deficient phase Li1?xCoO2, which was enhanced with laser power. Based on comparative Raman studies,

Seung-Wan Song; Kyoo-Seung Han; Hirofumi Fujita; Masahiro Yoshimura

2001-01-01

263

Picosecond timescale Raman processes and spectroscopy  

E-print Network

of obtaining Raman spectrometers Figure 2 Raman spectrum of benzophenone in ethanol. Top: ground—state benzophenone and solvent (EtOH) bands with 532 nm excitation. Bottom: Raman scattering from sample pumped at 355 nm. Pump—induced bands are resonance... Figure 3 Resonance Raman spectrum of myoglobin. Top: Deoxymyoglobin with 532 nm excitation. Middle: Carboxymyoglobin with 532 nm excitation. Bottom: Carboxymyoglobin pumped at 355 mm, probed at 532 mm at 30 Ps tine delay. FREQUENCY SHIFT (cm) + 1.5 nm...

Johnson, Carey K.; Dalickas, G. A.; Payne, S. A.; Hochstrasser, R. M.

1985-01-01

264

Nanoparticle Based Surface-Enhanced Raman Spectroscopy  

SciTech Connect

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

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

2005-01-03

265

Raman spectroscopy of protein-water interactions in aqueous solutions  

Microsoft Academic Search

Some conclusions about the effect of protein presence on water structure, as found by Raman spectroscopy, are presented here. An overall intensity decrease and strong spectral shape changes which are encountered in the OH stretching region when increasing protein concentration are explained in terms of a water model taking into account three water species with different Raman efficiency. The hydration

Fabrizio Cavatorta; Marco P. Fontana; Arnaldo Vecli

1976-01-01

266

COHERENT ANTI-STOKES RAMAN SPECTROSCOPY OF POLYCYCLIC AROMATIC HYDROCARBONS  

EPA Science Inventory

Coherent anti-Stokes Raman spectroscopy (CARS) was used to obtain Raman spectra of thirteen polycyclic aromatic hydrocarbons (PAHs) composed of between three and seven fused rings. The compounds were pumped in the resonance and preresonance regions to obtain the sensitivity neces...

267

Raman spectroscopy for quantifying cholesterol in intact coronary artery wall  

Microsoft Academic Search

The chemical composition of vascular lesions, an important determinant of plaque progression and rupture, can not presently be determined in vivo. Prior studies have shown that Raman spectroscopy can accurately quantify the amounts of major lipid classes and calcium salts in homogenized coronary artery tissue. This study determines how the relative cholesterol content, which is calculated from Raman spectra collected

Tjeerd J. Römer; James F. Brennan III; Tom C. Bakker Schut; Rolf Wolthuis; Ria C. M. van den Hoogen; Jef J. Emeis; Arnoud van der Laarse; Albert V. G. Bruschke; Gerwin J. Puppels

1998-01-01

268

Investigation of biomineralization by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Biomineralization is a process in which living organism grow composite materials consisting of inorganic and organic materials. This produces a composite material consisting of both inorganic and organic components, with superior mechanical properties. In the human body bone and dentin are both examples of biominerals. In this research Raman spectroscopy was used to characterize dentin from mice and human teeth, to determine composition. In the mouse tooth samples areas of irregular dentin were found, along the inside of the tooth, to be in the process of mineralization. By analyzing the samples along these areas we were able to determine the composition of dentin and track how it changed in these area. By analysis of the mineral to matrix ratio the areas of irregular dentin were determined to have less mineral present. Observations of other organic components and collagen in increased concentrations in this area suggested these area were in the process of biomineralization. The understanding of the structure of dentin and its biomineralization process is of crucial importance when trying reproduce dentin. Scientists and engineers are able to produce dentin minerals in vitro by culturing various dental stem cells. The ability to create dentin mineral from cells could lead to methods of repairing dentin in patients, or even lead to the creation of a completely engineered tooth. While dentin-like materials can be produced in a laboratory environment, analysis and comparison of the composition of these materials must be performed to ensure the mineral produced is consistent with dentin. Mineralized nodules from six different dental stem cell lines were cultured to produce a mineralized deposit. Utilizing Raman spectroscopy, we were able to determine cell source dependent differences in a variety of dental stem cells, and compare the mineral produced to native dentin. Orthopedic implants are implants used to replace damaged bone, examples include knee, hip and dental implants. These implants are designed to osteointegrate with the native healthy tissues in order to create a functionally stable and structural interface. Biomaterials such as hydroxyapatite and titania are known to increase the rate of bone regeneration in vivo.1 By accelerating the early response of bone forming cells to these implants, better fixation is achieved between the implant and the bone, shortening recovery times and increasing the viability of these implants. In the last part of this research an investigation of osteoblasts cultured at 14 days on five different heat-treated titania substrates was investigated by Raman spectroscopy, in order to observe the initial cellular response to the titania substrates. The heat-treatment of titania changes the amount of oxygen on it's surface which in turn effects the surface energy. A change in the surface energy of a material will affect the cellular response, by culturing cells on various heat-treated titania substrates a relationship between the surface energy and cellular response can be investigated. A faster cellular response would lead to an increased rate of bone regeneration shortening healing times and allowing for better fixation of the implant.

Fatscher, Robert William

269

Laser spectroscopy of desorbing molecules  

Microsoft Academic Search

In this article the application of tunable dye lasers to desorption phenomena is illuminated. These lasers provide radiation continuously tunable from 105 nm in the vacuum ultraviolet to about 10 µm in the mid-IR. By employing either laser induced fluorescence (LIF) or resonance enhanced multiphoton ionization (REMPI) spectroscopy almost all diatomic and many polyatomic molecules can be probed with the

H. Zacharias

1988-01-01

270

Detection of Physiologically Relevant Alcohol Concentrations Using Raman Spectroscopy  

E-print Network

This is the first step in a series of studies to test the feasibility of using Raman Spectroscopy (RS) to non-invasively detect physiologically relevant blood alcohol concentrations. Blood tests, urine tests, and the breathalyzer are currently...

McKay, Joshua L.

2006-08-16

271

Quantitative biological Raman spectroscopy for non-invasive blood analysis  

E-print Network

The long term goal of this project is the measurement of clinically-relevant analytes in the blood tissue matrix of human subjects using near-infrared Raman spectroscopy, with the shorter term research directed towards ...

Shih, Wei-Chuan

2007-01-01

272

Surface enhanced Raman spectroscopy on a flat graphene surface  

E-print Network

Surface enhanced Raman spectroscopy (SERS) is an attractive analytical technique, which enables single-molecule sensitive detection and provides its special chemical fingerprints. During the past decades, researchers have ...

Xu, Weigao

273

Fabrication of Raman biochip prototype by femtosecond laser micromachining  

NASA Astrophysics Data System (ADS)

In this work, a nanoscale surface-enhanced Raman scattering (SERS) substrate is fabricated by fs laser reduction and deposition. The conductive silver microstructures are also deposited in fs laser irradiated area on the glass surfaces. Based on this approach, we integrate the microelectronic circuit and micro-Raman substrate into a microfluidic chamber and form a prototype of Raman biochip for biosensing. Enhancement of Raman signal and control of temperature of the sensor are both achieved. This technique provides a great potential for integrating microelectronics and micro-Raman sensors on a single glass chip.

Zhou, Zenghui; Xu, Jian; He, Fei; Liao, Yang; Cheng, Ya; Xu, Zhizhan; Sugioka, Koji; Midorikawa, Katsumi

2010-08-01

274

Theory of Raman enhancement by two-dimensional materials: Applications for graphene-enhanced Raman spectroscopy  

E-print Network

We propose a third-order time-dependent perturbation theory approach to describe the chemical surface-enhanced Raman spectroscopy of molecules interacting with two-dimensional (2D) surfaces such as an ideal 2D metal and ...

Barros, E. B.

275

Characterization of the pigment xanthomonadin in the bacterial genus Xanthomonas using micro- and resonance Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We used micro- and resonance Raman spectroscopy with 785 nm and 514.5 nm laser excitation, respectively, to characterize a plant pathogenic bacteria, Xanthomonas axonopodis pv. dieffenbachiae D150. The bacterial genus Xathomonas is closely related to bacterial genus Stenotrophomonas that causes an infection in humans. This study has identified for the first time the unique Raman spectra of the carotenoid-like pigment xanthomonadin of the Xanthomonas strain. Xanthomonadin is a brominated aryl-polyene pigment molecule similar to carotenoids. Further studies were conducted using resonance Raman spectroscopy with 514.5 nm laser excitation on several strains of the bacterial genus Xanthomonas isolated from numerous plants from various geographical locations. The current study revealed that the Raman bands representing the vibrations (v1, v2, v3) of the polyene chain of xanthomonadin are 1003-1005 (v3), 1135-1138 (v2), and 1530 (v1). Overtone bands representing xanthomonadin were identified as 2264-2275 (2v2), and combinational bands at 2653-2662 (v1+ v2). The findings from this study validate our previous finding that the Raman fingerprints of xanthomonadin are unique for the genus Xanthomonas. This facilitates rapid identification (~5 minutes) of Xanthomonas spp. from bacterial culture plates. The xanthomonadin marker is different from Raman markers of many other bacterial genus including Agrobacterium, Bacillus, Clavibacter, Enterobacter, Erwinia, Microbacterium, Paenibacillus, and Ralstonia. This study also identified Xanthomonas spp. from bacterial strains isolated from a diseased wheat sample on a culture plate.

Paret, Mathews L.; Sharma, Shiv K.; Misra, Anupam K.; Acosta, Tayro; deSilva, Asoka S.; Vowell, Tomie; Alvarez, Anne M.

2012-06-01

276

Raman spectroscopy of natron: shedding light on ancient Egyptian mummification.  

PubMed

The mummification ritual in ancient Egypt involved the evisceration of the corpse and its desiccation using natron, a naturally occurring evaporitic mineral deposit from the Wadi Natrun, Egypt. The deposit typically contains sodium carbonate, sodium bicarbonate and impurities of chloride and sulfate as its major elemental components. It is believed that the function of the natron was to rapidly remove the water from the cadaver to prevent microbial attack associated with subsequent biological tissue degradation and putrefaction. Several specimens of natron that were recently collected from the Wadi Natrun contained coloured zones interspersed with the mineral matrix that are superficially reminiscent of extremophilic cyanobacterial colonisation found elsewhere in hot and cold deserts. Raman spectroscopy of these specimens using visible and near-infrared laser excitation has revealed not only the mineral composition of the natron, but also evidence for the presence of cyanobacterial colonies in several coloured zones observed in the mineral matrix. Key Raman biosignatures of carotenoids, scytonemin and chlorophyll have been identified. PMID:17404715

Edwards, Howell G M; Currie, Katherine J; Ali, Hassan R H; Jorge Villar, Susana E; David, A Rosalie; Denton, John

2007-06-01

277

Raman spectroscopy in biomedicine – non-invasive in vitro analysis of cells and extracellular matrix components in tissues  

PubMed Central

Raman spectroscopy is an established laser-based technology for the quality assurance of pharmaceutical products. Over the past few years, Raman spectroscopy has become a powerful diagnostic tool in the life sciences. Raman spectra allow assessment of the overall molecular constitution of biological samples, based on specific signals from proteins, nucleic acids, lipids, carbohydrates, and inorganic crystals. Measurements are non-invasive and do not require sample processing, making Raman spectroscopy a reliable and robust method with numerous applications in biomedicine. Moreover, Raman spectroscopy allows the highly sensitive discrimination of bacteria. Rama spectra retain information on continuous metabolic processes and kinetics such as lipid storage and recombinant protein production. Raman spectra are specific for each cell type and provide additional information on cell viability, differentiation status, and tumorigenicity. In tissues, Raman spectroscopy can detect major extracellular matrix components and their secondary structures. Furthermore, the non-invasive characterization of healthy and pathological tissues as well as quality control and process monitoring of in vitro-engineered matrix is possible. This review provides comprehensive insight to the current progress in expanding the applicability of Raman spectroscopy for the characterization of living cells and tissues, and serves as a good reference point for those starting in the field. PMID:23161832

Brauchle, Eva; Schenke-Layland, Katja

2013-01-01

278

Raman Amplification of Laser Pulses in Microcapillary Plasmas  

E-print Network

by the second harmonic of a Nd:YAG laser at A, = 532 nm with 150 mJ in 5 ns (FWHM). The seed pulseRaman Amplification of Laser Pulses in Microcapillary Plasmas Y. Ping, I. Geltner, A. Morozov, N. J. Fisch and S. Suckewer Princeton University, Princeton, NJ 08540 Abstract. Raman amplification

279

Coherent and spontaneous Raman spectroscopy in shocked and unshocked liquids  

SciTech Connect

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

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

1985-01-01

280

A handheld laser scanning confocal reflectance imaging–confocal Raman microspectroscopy system  

PubMed Central

Confocal reflectance microscopy and confocal Raman spectroscopy have shown potential for non-destructive analysis of samples at micron-scale resolutions. Current studies utilizing these techniques often employ large bench-top microscopes, and are not suited for use outside of laboratory settings. We have developed a microscope which combines laser scanning confocal reflectance imaging and confocal Raman spectroscopy into a compact handheld probe that is capable of high-resolution imaging and spectroscopy in a variety of settings. The compact size of the probe is largely due to the use of a MEMS mirror for beam scanning. The probe is capable of axial resolutions of up to 4 ?m for the confocal imaging channel and 10 ?m for the confocal Raman spectroscopy channel. Here, we report instrument design, characterize optical performance, and provide images and spectra from normal skin to demonstrate the instrument’s capabilities for clinical diagnostics. PMID:22435097

Patil, Chetan A.; Arrasmith, Christopher L.; Mackanos, Mark A.; Dickensheets, David L.; Mahadevan-Jansen, Anita

2012-01-01

281

Continuous-wave solid-state two-Stokes Raman laser  

SciTech Connect

We report an experimental study of the first cw solid-state Raman laser operating simultaneously at the frequencies of the first and second Stokes components. Simultaneous generation is ensured by a cavity with an enhanced finesse at both Stokes frequencies. The threshold pump powers for the first (3.4 W) and second (3.67 W) Stokes components suggest that the second Stokes generation follows a cascade mechanism. We demonstrate for the first time Raman conversion with intensity stability exceeding the pump radiation stability and show that this approach may find application in Raman spectroscopy. (special issue devoted to the 80th birthday of S.A. Akhmanov)

Grabchikov, A S; Lisinetskii, V A; Orlovich, V A [B.I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, Minsk (Belarus); Schmitt, M; Schluecker, S; Kuestner, B; Kiefer, W [Institut fuer Physikalische Chemie, Universitat Wuerzburg, Wuerzburg (Germany)

2009-07-31

282

Correlation of Surface Enhanced Raman Spectroscopy and Nanoparticle Aggregation with Rhodamine 6G.  

E-print Network

?? Surface enhanced Raman spectroscopy (SERS) has fascinated the analytical chemistry field for decades. The SERS phenomenon has progressively leveraged the inherently insensitive Raman phenomenon… (more)

Hoff, Christopher Aaron

2013-01-01

283

Fiber Laser Based Nonlinear Spectroscopy  

E-print Network

practical. A nonlinear spectroscopy tool based on a single fiber laser, with electrically controlled wavelength-tuning and spectral resolution enhanced by a pulse shaping technique, will efficiently produce optical excitation that allows quantitative...

Adany, Peter

2012-08-31

284

Application of Raman spectroscopy technology to studying Sudan I  

NASA Astrophysics Data System (ADS)

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

Li, Gang; Zhang, Guoping; Chen, Chen

2006-06-01

285

Internal multiple-scattering hole-enhanced Raman spectroscopy: improved backscattering Fourier transform Raman sampling in pharmaceutical tablets utilizing cylindrical-conical holes.  

PubMed

The benefits of Raman signal enhancement and improved measurement precision are demonstrated using 180° backscattering Fourier transform Raman (FT-Raman) spectroscopy from drilled cylindrical-conical holes within pharmaceutical tablet cores. Multiple scattering of the incident laser light within the holes results in an increased Raman signal due to the larger Raman sampling volume. This is important for overcoming typical sub-sampling issues encountered when employing FT-Raman backscattering of heterogeneous pharmaceutical tablets. Hole depth and diameter were found to be important experimental parameters and were optimized to yield the greatest signal enhancement. The FT-Raman spectra collected using backscattering from cylindrical-conical holes is compared to typical 180° backscattering from flat surfaces using tablet cores of Excedrin® and Vivarin®. Raman chemical images are used to establish a representative sampling area. We observe a three- to five-fold increase in the Raman intensity and a two-fold improvement in the measurement precision when sampling from cylindrical-conical holes rather than classic backscattering from flat tablet cores. Self-absorption effects on analyte band ratios are negligible in the fingerprint region but are more significant at the higher near-infrared (NIR) absorbances found in the C-H/O-H/-N-H stretching region. The sampling technique will facilitate developing quantitative FT-Raman methods for application to pharmaceutical tablets using the fingerprint spectral region. PMID:22800376

Larkin, Peter J; Santangelo, Matthew; Šaši?, Slobodan

2012-08-01

286

Remote Raman Spectroscopy of Minerals at Elevated Temperature Relevant to Venus Exploration  

NASA Technical Reports Server (NTRS)

We have used a remote time-resolved telescopic Raman system equipped with 532 nm pulsed laser excitation and a gated intensified CCD (ICCD) detector for measuring Raman spectra of a number of minerals at high temperature to 970 K. Remote Raman measurements were made with samples at 9-meter in side a high-temperature furnace by gating the ICCD detector with 2 micro-sec gate to minimize interference from blackbody emission from mineral surfaces at high temperature as well as interference from ambient light. A comparison of Raman spectra of gypsum (CaSO4.2H2O), dolomite (CaMg(CO3)2), and olivine (Mg2Fe2-xSiO4), as a function of temperature shows that the Raman lines remains sharp and well defined even in the high-temperature spectra. In the case of gypsum, Raman spectral fingerprints of CaSO4.H2O at 518 K were observed due to dehydration of gypsum. In the case of dolomite, partial mineral dissociation was observed at 973 K at ambient pressure indicating that some of the dolomite might survive on Venus surface that is at approximately 750 K and 92 atmospheric pressure. Time-resolved Raman spectra of low clino-enstatite (MgSiO3) measured at 75 mm from the sample in side the high-temperature furnace also show that the Raman lines remains sharp and well defined in the high temperature spectra. These high-temperature remote Raman spectra of minerals show that time-resolved Raman spectroscopy can be used as a potential tool for exploring Venus surface mineralogy at shorter (75 mm) and long (9 m) distances from the samples both during daytime and nighttime. The remote Raman system could also be used for measuring profiles of molecular species in the dense Venus atmosphere during descent as well as on the surface.

Sharma, Shiv K.; Misra, Anupam K.; Singh, Upendra N.

2008-01-01

287

Applications of laser Raman and FT-IR techniques to leprology, neurology, bacteriology and traumatology  

Microsoft Academic Search

The application of Fourier transform infrared spectroscopy and laser Raman spectroscopy for obtaining structural information\\u000a about the subtle changes occurring at the molecular level following leprosy, pulmonary tuberculosis, infected burns, epilepsy\\u000a and Duchenne muscular dystrophy (DMD) are reported in this paper. It is shown that IR spectra exhibit specific signals for\\u000a each disease. Results of the observed bands of hemoproteins

S. Mishra; Ravindra Kumar; S. K. Aryal; S. Kumar; Rajesh Kumar; M. M. Bajaj

1990-01-01

288

LIGHT INDUCED TELLURIUM ENRICHMENT ON CDZNTE CRYSTALSURFACES DETECTED BY RAMAN SPECTROSCOPY  

SciTech Connect

Synthetic CdZnTe or 'CZT' crystals can be grown under controlled conditions to produce high quality crystals to be used as room temperature radiation detectors. Even the best crystal growth methods result in defects, such as tellurium secondary phases, that affect the crystal's performance. In this study, CZT crystals were analyzed by micro Raman spectroscopy. The growth of Te rich areas on the surface was induced by low powered lasers. The growth was observed versus time with low power Raman scattering and was observed immediately under higher power conditions. The detector response was also measured after induced Te enrichment.

Hawkins, S; Eliel Villa-Aleman, E; Martine Duff, M; Douglas02 Hunter, D

2007-10-29

289

Light-Induced Tellurium Enrichment on CdZnTe Crystal Surfaces Detected by Raman Spectroscopy  

SciTech Connect

CdZnTe (CZT) crystals can be grown under controlled conditions to produce high-quality crystals to be used as room-temperature radiation detectors. Even the best crystal growth methods result in defects, such as tellurium secondary phases, that affect the crystal's performance. In this study, CZT crystals were analyzed by micro-Raman spectroscopy. The growth of Te rich areas on the surface was induced by low-power lasers. The growth was observed versus time with low-power Raman scattering and was observed immediately under higher-power conditions. The detector response was also measured after induced Te enrichment.

Hawkins, Samantha A.; Villa-Aleman, Eliel; Duff, Martine C.; Hunter, Doug B.; Burger, Arnold; Groza, Michael; Buliga, Vladimir; Black, David R. (SRNL); (NIST); (Fisk U)

2008-12-08

290

Raman Spectroscopy of UH3 from the Hydrogen Corrosion of Uranium  

SciTech Connect

Hydrogen reacts with a uranium surface to form a fine, pyrophoric metal power (UH{sub 3}). Few spectroscopic studies have been conducted to study this reaction. Advances in Raman spectroscopy permit the application of the Raman method to formally difficult areas of chemistry such as the hydrogen corrosion of uranium: availability of multiple laser excitation wavelengths; fiber optics delivery and collection systems; upgraded instrumentation and detection techniques; and development of special enclosed in situ reactor cells. UH{sub 3} vibrations are expected to occur at low frequencies due to extended U-H-U structure.

Smyrl, N. R.; Stowe, A. C.; Powell, G. L.

2011-05-31

291

Multidimensional resonance Raman spectroscopy by six-wave mixing in the deep UV.  

PubMed

Two-dimensional (2D) resonance Raman spectroscopies hold great potential for uncovering photoinduced relaxation processes in molecules but are not yet widely applied because of technical challenges. Here, we describe a newly developed 2D resonance Raman experiment operational at the third-harmonic of a Titanium-Sapphire laser. High-sensitivity and rapid data acquisition are achieved by combining spectral interferometry with a background-free (six-pulse) laser beam geometry. The third-harmonic laser pulses are generated in a filament produced by the fundamental and second-harmonic pulses in neon gas at pressures up to 35 atm. The capabilities of the setup are demonstrated by probing ground-state wavepacket motions in triiodide. The information provided by the experiment is explored with two different representations of the signal. In one representation, Fourier transforms are carried out with respect to the two experimentally controlled delay times to obtain a 2D Raman spectrum. Further insights are derived in a second representation by dispersing the signal pulse in a spectrometer. It is shown that, as in traditional pump-probe experiments, the six-wave mixing signal spectrum encodes the wavepacket's position by way of the (time-evolving) emission frequency. Anharmonicity additionally induces dynamics in the vibrational resonance frequency. In all cases, the experimental signals are compared to model calculations based on a cumulant expansion approach. This study suggests that multi-dimensional resonance Raman spectroscopies conducted on systems with Franck-Condon active modes are fairly immune to many of the technical issues that challenge off-resonant 2D Raman spectroscopies (e.g., third-order cascades) and photon-echo experiments in the deep UV (e.g., coherence spikes). The development of higher-order nonlinear spectroscopies operational in the deep UV is motivated by studies of biological systems and elementary organic photochemistries. PMID:25240351

Molesky, Brian P; Giokas, Paul G; Guo, Zhenkun; Moran, Andrew M

2014-09-21

292

Multidimensional resonance raman spectroscopy by six-wave mixing in the deep UV  

NASA Astrophysics Data System (ADS)

Two-dimensional (2D) resonance Raman spectroscopies hold great potential for uncovering photoinduced relaxation processes in molecules but are not yet widely applied because of technical challenges. Here, we describe a newly developed 2D resonance Raman experiment operational at the third-harmonic of a Titanium-Sapphire laser. High-sensitivity and rapid data acquisition are achieved by combining spectral interferometry with a background-free (six-pulse) laser beam geometry. The third-harmonic laser pulses are generated in a filament produced by the fundamental and second-harmonic pulses in neon gas at pressures up to 35 atm. The capabilities of the setup are demonstrated by probing ground-state wavepacket motions in triiodide. The information provided by the experiment is explored with two different representations of the signal. In one representation, Fourier transforms are carried out with respect to the two experimentally controlled delay times to obtain a 2D Raman spectrum. Further insights are derived in a second representation by dispersing the signal pulse in a spectrometer. It is shown that, as in traditional pump-probe experiments, the six-wave mixing signal spectrum encodes the wavepacket's position by way of the (time-evolving) emission frequency. Anharmonicity additionally induces dynamics in the vibrational resonance frequency. In all cases, the experimental signals are compared to model calculations based on a cumulant expansion approach. This study suggests that multi-dimensional resonance Raman spectroscopies conducted on systems with Franck-Condon active modes are fairly immune to many of the technical issues that challenge off-resonant 2D Raman spectroscopies (e.g., third-order cascades) and photon-echo experiments in the deep UV (e.g., coherence spikes). The development of higher-order nonlinear spectroscopies operational in the deep UV is motivated by studies of biological systems and elementary organic photochemistries.

Molesky, Brian P.; Giokas, Paul G.; Guo, Zhenkun; Moran, Andrew M.

2014-09-01

293

Combined Raman spectrometer/laser-induced breakdown spectrometer for the next ESA mission to Mars.  

PubMed

Among the different instruments that have been pre-selected to be on-board the Pasteur payload on ExoMars is the Raman/laser induced breakdown spectroscopy (LIBS) instrument. Raman spectroscopy and LIBS will be integrated into a single instrument sharing many hardware commonalities. An international team under the lead of TNO has been gathered to produce a design concept for a combined Raman spectrometer/LIBS elegant bread-board (EBB). The instrument is based on a specially designed, extremely compact, spectrometer with high resolution over a large wavelength range, suitable for both Raman spectroscopy and LIBS measurements. Low mass, size and power consumption are the main drivers of the instrument's design concept. In this paper, science objectives for the combined instrument are detailed. Background information on Raman spectroscopy and LIBS are presented, focussing on the synergy of these two techniques. In the last section, the instrument concept resulting from the assessment of the feasibility of the combined Raman/LIBS EBB is presented. PMID:17466575

Bazalgette Courrèges-Lacoste, Grégory; Ahlers, Berit; Pérez, Fernando Rull

2007-12-15

294

Study of normal colorectal tissue by FT-Raman spectroscopy  

Microsoft Academic Search

FT-Raman spectroscopy was employed to study normal human colorectal tissues in vitro with the aim of evaluating the spectral\\u000a differences of the complex colon mucous in order to establish a characteristic Raman spectrum. The samples were collected\\u000a from 39 patients, providing 144 spectra for the statistical analysis. The results enable one to estabilish three well-defined\\u000a spectroscopic groups of non-altered coloretal

P. O. Andrade; R. A. Bitar; K. Yassoyama; H. Martinho; A. M. E. Santo; P. M. Bruno; A. A. Martin

2007-01-01

295

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

SciTech Connect

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

Martinez-Espinosa, J. C.; Gonzalez-Solis, J. L.; Miranda-Beltran, M. L.; Soria-Fregoso, C.; Medina-Valtierra, J.; Sanchez-Gomez, R. [Centro Universitario de Lagos, Universidad de Guadalajara Enrique Diaz de Leon S/N, Paseo de la Montana, CP 47460, Lagos de Moreno, Jalisco (Mexico); Frausto-Reyes, C. [Centro de Investigaciones en Optica, A. C. Prolongacion Constitucion 607, Fracc. Reserva Lomas Bonita, CP 20200, Aguascalientes (Mexico)

2008-08-11

296

Spatially offset Raman spectroscopy for explosives detection through difficult (opaque) containers  

NASA Astrophysics Data System (ADS)

With the continuing threat to aviation security from homemade explosive devices, the restrictions on taking a volume of liquid greater than 100 ml onto an aircraft remain in place. From January 2014, these restrictions will gradually be reduced via a phased implementation of technological screening of Liquids, Aerosols and Gels (LAGs). Raman spectroscopy offers a highly sensitive, and specific, technique for the detection and identification of chemicals. Spatially Offset Raman Spectroscopy (SORS), in particular, offers significant advantages over conventional Raman spectroscopy for detecting and recognizing contents within optically challenging (Raman active) containers. Containers vary enormously in their composition; glass type, plastic type, thickness, reflectance, and pigmentation are all variable and cause an infinite range of absorbances, fluorescence backgrounds, Rayleigh backscattered laser light, and container Raman bands. In this paper we show that the data processing chain for Cobalt Light Systems' INSIGHT100 bottlescanner is robust to such variability. We discuss issues of model selection for the detection stage and demonstrate an overall detection rate across a wide range of threats and containers of 97% with an associated false alarm rate of 0.1% or lower.

Maskall, Guy T.; Bonthron, Stuart; Crawford, David

2013-10-01

297

Laser spectroscopy at accelerator facilities  

SciTech Connect

The use of lasers in exciting fast atomic and molecular ions produced in accelerators is discussed. Collinear excitation of the ions is most efficient, and several examples of laser-induced fluorescence are given. These include tests of relativistic atomic structure, and atomic and molecular hyperfine measurements. Higher precision can be attained using rf double-resonance techniques in some cases. A variant of this technique, the raman double-resonance technique, is also introduced. The production of an optically-pumped polarized target is also described, together with an experiment on polarized electron pick-up in a fast heavy-ion beam. 16 refs., 19 figs., 1 tab.

Berry, H.G.

1989-01-01

298

Nd:Glass-Raman laser for water vapor dial  

NASA Technical Reports Server (NTRS)

A tunable solid-state Raman shifted laser which was used in a water vapor Differential Absorption Lidar (DIAL) system at 9400 A is described. The DIAL transmitter is based on a tunable glass laser operating at 1.06 microns, a hydrogen Raman cell to shift the radiation to 1.88 microns, and a frequency doubling crystal. The results of measurements which characterize the output of the laser with respect to optimization of optical configuration and of Raman parameters were reported. The DIAL system was also described and preliminary atmospheric returns shown.

Kagann, R. H.; Petheram, J. C.; Rosenberg, A.

1986-01-01

299

Characterisation of uranium oxides by micro-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The micro-Raman spectra of four oxides of uranium are presented and discussed. Attention is drawn to certain features and trends of the spectra which lead to their use in the characterisation of uranium oxide particles. Much lower laser powers than are normally used for Raman measurements have proved possible because of the high collection efficiency of the microscope optics and the multiscanning capability of the spectrometer. Raman spectra can now be obtained for materials earlier thought to be too unstable to survive the long periods of continuous radiation necessary.

Allen, Geoffrey C.; Butler, Ian S.; Nguyen, Anh Tuan

1987-01-01

300

Modulated Fourier Transform Raman Fiber-Optic Spectroscopy  

NASA Technical Reports Server (NTRS)

A modification to a commercial Fourier Transform (FT) Raman spectrometer is presented for the elimination of thermal backgrounds in the FT Raman spectra. The modification involves the use of a mechanical optical chopper to modulate the continuous wave laser, remote collection of the signal via fiber optics, and connection of a dual-phase digital-signal-processor (DSP) lock-in amplifier between the detector and the spectrometer's collection electronics to demodulate and filter the optical signals. The resulting Modulated Fourier Transform Raman Fiber-Optic Spectrometer is capable of completely eliminating thermal backgrounds at temperatures exceeding 300 C.

Jensen, Brian J. (Inventor); Cooper, John B. (Inventor); Wise, Kent L. (Inventor)

2000-01-01

301

Using micro-Raman spectroscopy for nasopharyngeal cancerous tissue detection  

NASA Astrophysics Data System (ADS)

Micro-Raman spectroscopy is widely used for non-invasive tissue diagnosis and detection, as it provides detailed information about biomolecular composition, structure, and interaction of tissue. In this work, micro-Raman spectroscopy was used to investigate non-cancerous and cancerous nasopharyngeal tissues. The obtained nasopharyngeal tissue samples in vitro are divided into two groups: cancerous (n=12, undifferentiated non-keratinizing carcinomas) and non-cancerous (n=10, 7 chronic inflammations, 2 lymphomas and 1 lymphocytosis). Firstly, we analyzed the Raman spectra in the fingerprint (FP, 400-1800cm-1) region acquired. Preliminary results showed that there are some spectral differences in different pathological conditions. Furthermore, Raman spectra from cancerous and non-cancerous nasopharyngeal tissue in the high wavenumber region (HW, 2800-3100cm-1) were also reported for the first time. After detailed analysis, we achieved significant differences in Raman bands at 2854, 2874, 2934, and 3067cm-1 between cancerous and non-cancerous nasopharyngeal tissues. This study demonstrates that both fingerprint and high wavenumber regions of micro-Raman spectroscopy have the potential for the early detection of nasopharyngeal carcinomas.

Wu, Shanshan; Sun, Liqing; Chen, Maowen; Lin, Jia; Cao, Gang; Huang, Wei; Chen, Rong

2014-09-01

302

Observation of large electron drift velocities in InN by ultrafast Raman spectroscopy  

Microsoft Academic Search

Electron transport in an InN film grown on GaN has been studied by transient Raman spectroscopy at T=300 K. Our experimental results demonstrate that under the subpicosecond laser excitation and probing, electron drift velocity of carriers in the ? valley can exceed its steady-state value by as much as 40%. Electron velocities have been found to cut off at around

K. T. Tsen; C. Poweleit; D. K. Ferry; Hai Lu; William J. Schaff

2005-01-01

303

Observation of large electron drift velocities in InN by ultrafast Raman spectroscopy  

Microsoft Academic Search

Electron transport in an InN film grown on GaN has been studied by transient Raman spectroscopy at T=300 K. Our experimental results demonstrate that under the subpicosecond laser excitation and probing, electron drift velocity of carriers in the Gamma valley can exceed its steady-state value by as much as 40%. Electron velocities have been found to cut off at around

K. T. Tsen; C. Poweleit; D. K. Ferry; Hai Lu; William J. Schaff

2005-01-01

304

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

305

Excited excitonic states in 1L, 2L, 3L, and bulk WSe2 observed by resonant Raman spectroscopy.  

PubMed

Resonant Raman spectroscopy (RRS) is a very useful tool to study physical properties of materials since it provides information about excitons and their coupling with phonons. We present in this work a RRS study of samples of WSe2 with one, two, and three layers (1L, 2L, and 3L), as well as bulk 2H-WSe2, using up to 20 different laser lines covering the visible range. The first- and second-order Raman features exhibit different resonant behavior, in agreement with the double (and triple) resonance mechanism(s). From the laser energy dependence of the Raman intensities (Raman excitation profile, or REP), we obtained the energies of the excited excitonic states and their dependence with the number of atomic layers. Our results show that Raman enhancement is much stronger for the excited A' and B' states, and this result is ascribed to the different exciton-phonon coupling with fundamental and excited excitonic states. PMID:25162682

del Corro, Elena; Terrones, Humberto; Elias, Ana; Fantini, Cristiano; Feng, Simin; Nguyen, Minh An; Mallouk, Thomas E; Terrones, Mauricio; Pimenta, Marcos A

2014-09-23

306

Two-dimensional Raman-terahertz spectroscopy of water  

PubMed Central

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

Savolainen, Janne; Ahmed, Saima; Hamm, Peter

2013-01-01

307

Analysis of hydrocarbon fuel properties by means of Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The project is focused on the determination of Raman spectra of hydrocarbon fuel samples using a spectrometer employing a silicon linear array detector which has a spectral range of 400 nm to 1.1 mum. The spectra are processed using chemometric techniques in order to determine the concentrations of the tracked blend components and analytical values that are used to ensure that desired specifications are achieved. The verification is based on the American Standard Testing Methods procedures for the determination of the motor, research, and road octane numbers, simulated distillation and Reid vapour pressure. Blending is one of the most important steps in the final production of hydrocarbon fuels; as many as ten complex components are mixed to achieve the desired properties of the final product. Traditionally, blending relies on well-established analytical methods such as gas chromatography for component and simulated distillation analysis, knock engines and near infrared spectroscopy for octane analysis. All of these methods are reliable and accurate, but their results are not available in real time but rather with a substantial delay, since it is in the nature of the methods that the sample must be transported from a test site to the site where the instrument is located. Additional time is required for performing the analytical procedure; e.g. the results of a gas chromatography analysis are only available from minutes to hours after the sample has been introduced into the instrument. Consequently, the results, although accurate, become only available after the process of blending has been completed. The thesis describes an implementation of a Raman spectroscopic method, which is novel in the given context, since it allows monitoring and control of the blending process online, in real time. A Raman spectrometer was designed, using a solid state laser for excitation (785 nm, 800 mW), a blazed grating for the diffraction (600 lines-per-millimeter, 750 nm blaze, 635 nm spectral range). The spectrometer was integrated with a silicon, linear array detector, cooled with a Peltier effect stack. In order to make the optical system of the spectrometer suitable for industrial use, the instrument comprised optical fiber conduits that have alleviated the alignment difficulties, eliminated the sample transport delay, and allowed the sample collection via an optical probe. The spectrometer has been tested in an industrial environment and the results obtained compared with the data yielded by the traditional analytical method of gas chromatography, and the contemporary near infrared spectroscopy. For benzene, which was used as a standard, the noise-limited detection limit of the spectrometer was 1600 ppmv for the Raman spectrometer, which compares to the detection limit of 5000 ppmv of the near infrared spectrometer, and the typical value of 10 ppm yielded by a gas chromatograph. The time interval between the sampling and availability of results was from 10 to 30 seconds for the near infrared the Raman instruments, which compared favourably with the approximately 5 to 120 minute interval required in gas chromatography.

Flatley, Martin W.

308

Development of a nanosecond-laser-pumped Raman amplifier for short laser pulses in plasma  

E-print Network

of solid-state optics. The amplifica- tion of short laser pulses is achieved by energy transfer from a longDevelopment of a nanosecond-laser-pumped Raman amplifier for short laser pulses in plasma Y. Ping,1 December 2009 Progress on developing a plasma amplifier/compressor based on stimulated Raman scattering

309

Raman spectroscopy of perovskite and post-perovskite phases of MgGeO3 to 123 GPa  

E-print Network

Raman spectroscopy of perovskite and post-perovskite phases of MgGeO3 to 123 GPa Sang-Heon Shim a 19 May 2007 Editor: G.D. Price Available online 26 May 2007 Abstract Raman spectra of the perovskite (Pv) and post-perovskite (PPv) phases of MgGeO3 were measured in the laser-heated diamond cell up

Duffy, Thomas S.

310

Raman and photoluminescence spectroscopy of free-standing GaN separated from sapphire substrates by 532 nm Nd:YAG laser lift-off  

Microsoft Academic Search

Gallium nitride (GaN) thin-films grown on sapphire substrates were lifted onto silicon wafer using a laser lift-off (LLO) process. The pulsed second harmonic (532nm) Nd:YAG laser used in our LLO experiments had a photon energy (2.33eV) much smaller than the band gap energy of hexagonal GaN (3.41eV). The free carriers in GaN absorbed the laser subsequently heated up the material.

H. P Ho; K. C Lo; G. G Siu; C Surya; K. F Li; K. W Cheah

2003-01-01

311

Trace vapour detection at room temperature using Raman spectroscopy.  

PubMed

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

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

2014-04-21

312

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

313

Experimental analysis of emission linewidth narrowing in a pulsed KGd(WO ?) ? Raman laser.  

PubMed

The linewidth of a KGd(WO ?) ? (KGW) intracavity pumped Raman laser is analyzed experimentally for different configurations of the Raman and pump laser resonators: with narrow and broadband pump emission profiles, with and without linewidth narrowing elements in the Raman laser resonator, with and without injection seeding into the Raman cavity. The benefits of a narrow linewidth pump source in combination with linewidth narrowing elements in the Raman laser cavity for the efficient linewidth narrowing of the Raman laser emission are explained. 20 kW peak-power pulses at 1156 nm with 0.43 cm?¹ emission linewidth are demonstrated from an injection seeded KGW Raman laser. PMID:25321552

Savitski, Vasili G

2014-09-01

314

Dengue blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

315

Stimulated Raman Scattering Microscopy with a Robust Fibre Laser Source  

PubMed Central

Stimulated Raman Scattering microscopy allows label-free chemical imaging and has enabled exciting applications in biology, material science, and medicine. It provides a major advantage in imaging speed over spontaneous Raman scattering and has improved image contrast and spectral fidelity compared to coherent anti-Stokes Raman. Wider adoption of the technique has, however, been hindered by the need for a costly and environmentally sensitive tunable ultra-fast dual-wavelength source. We present the development of an optimized all-fibre laser system based on the optical synchronization of two picosecond power amplifiers. To circumvent the high-frequency laser noise intrinsic to amplified fibre lasers, we have further developed a high-speed noise cancellation system based on voltage-subtraction autobalanced detection. We demonstrate uncompromised imaging performance of our fibre-laser based stimulated Raman scattering microscope with shot-noise limited sensitivity and an imaging speed up to 1 frame/s. PMID:25313312

Freudiger, Christian W.; Yang, Wenlong; Holtom, Gary R.; Peyghambarian, Nasser; Xie, X. Sunney; Kieu, Khanh Q.

2014-01-01

316

A handheld laser scanning confocal reflectance imagingconfocal Raman  

E-print Network

­ 594 (2007). 5. M. Claybourn and M. Ansell, "Using Raman spectroscopy to solve crime: inks, questioned. Speicher, and F. Hofer, "Different staining substances were used in decorative and therapeutic tattoos

Maxwell, Bruce D.

317

Stimulated Raman Side Scattering in Laser Wakefield Acceleration  

SciTech Connect

Stimulated Raman side scattering of an ultrashort high power laser pulse is studied in experiments on laser wakefield acceleration. Experiments and simulations reveal that stimulated Raman side scattering occurs at the beginning of the interaction, that it contributes to the evolution of the pulse prior to wakefield formation, and also that it affects the quality of electron beams generated. The relativistic shift of the plasma frequency is measured.

Matsuoka, T.; McGuffey, C.; Cummings, P. G.; Horovitz, Y.; Dollar, F.; Chvykov, V.; Kalintchenko, G.; Rousseau, P.; Yanovsky, V.; Bulanov, S. S.; Thomas, A. G. R.; Maksimchuk, A.; Krushelnick, K. [Center for Ultrafast Optical Science and FOCUS Center, University of Michigan, Ann Arbor, Michigan 48109 (United States)

2010-07-16

318

Monitoring of aqueous humor metabolites using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Laser Raman scattering has been used to monitor glucose and lactate metabolites within aqueous humor specimens obtained from nine human eyes during cataract surgery. Nine postmortem rabbit eyes were also investigated. Raman measurements were obtained using a single grating Raman spectrometer with a liquid nitrogen cooled CCD. A 514.5 nm line from an argon laser was used to illuminate capillaries containing several microliters of aqueous humor. A water background was subtracted from each of the aqueous humor Raman spectra. This experimental system was calibrated so that each metabolite in water could be measured down to 0.1 weight percent. Raman peaks indicative of the stretching vibrations of methylene and methyl groups associated with glucose and lactate, respectively, were observed in the human specimens. A second stretching mode characteristic of lactate between the carbon atom and either the carboxylic acid group or carboxylate ion group was also observed providing a distinguishing feature between the glucose and lactate Raman peaks. Similar structure was observed from the rabbit specimens, but these samples have recently been found to have been contaminated during euthanasia.

Wicksted, James P.; Erckens, Roel J.; Motamedi, Massoud; March, Wayne F.

1994-05-01

319

Surface enhanced Raman spectroscopy of neurotransmitters  

NASA Astrophysics Data System (ADS)

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

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

1989-10-01

320

Raman spectroscopy and microscopy based on mechanical force detection.  

PubMed

The Raman effect is typically observed by irradiating a sample with an intense light source and detecting the minute amount of frequency shifted scattered light. We demonstrate that Raman molecular vibrational resonances can be detected directly through an entirely different mechanism-namely, a force measurement. We create a force interaction through optical parametric down conversion between stimulated, Raman excited, molecules on a surface and a cantilevered nanometer scale probe tip brought very close to it. Spectroscopy and microscopy on clusters of molecules have been performed. Single molecules within such clusters are clearly resolved in the Raman micrographs. The technique can be readily extended to perform pump probe experiments for measuring inter- and intramolecular couplings and conformational changes at the single molecule level. PMID:22087048

Rajapaksa, I; Kumar Wickramasinghe, H

2011-10-17

321

Raman spectroscopy and microscopy based on mechanical force detection  

NASA Astrophysics Data System (ADS)

The Raman effect is typically observed by irradiating a sample with an intense light source and detecting the minute amount of frequency shifted scattered light. We demonstrate that Raman molecular vibrational resonances can be detected directly through an entirely different mechanism—namely, a force measurement. We create a force interaction through optical parametric down conversion between stimulated, Raman excited, molecules on a surface and a cantilevered nanometer scale probe tip brought very close to it. Spectroscopy and microscopy on clusters of molecules have been performed. Single molecules within such clusters are clearly resolved in the Raman micrographs. The technique can be readily extended to perform pump probe experiments for measuring inter- and intramolecular couplings and conformational changes at the single molecule level.

Rajapaksa, I.; Kumar Wickramasinghe, H.

2011-10-01

322

Non-resonant and non-enhanced Raman correlation spectroscopy.  

PubMed

We present the first non-resonant and non-enhanced Raman correlation spectroscopy experiments. They are conducted on a confocal microscope combined with a Raman spectrometer. The thermal fluctuations of the Raman intensities scattered by dispersions of polystyrene particles of sub-micrometric diameters are measured and analysed by deriving the autocorrelation functions (ACFs) of the intensities. We show that for particles of diameter down to 200 nm, RCS measurements are successfully obtained in spite of the absence of any source of amplification of the Raman signal. For particles of diameter ranging from 200 to 750 nm, the ACFs present a time-decay behaviour in accordance with the model of free Brownian particles. For particles of 1000 nm in diameter, the AFCs present a different behaviour with a much smaller characteristic time. This results from the dynamics of a single-Brownian particle trapped in the confocal volume by the optical forces of the focus spot. PMID:23842329

Barbara, A; Dubois, F; Quémerais, P; Eng, L

2013-07-01

323

Combining optical trapping in a microfluidic channel with simultaneous micro-Raman spectroscopy and motion detection  

NASA Astrophysics Data System (ADS)

Since their invention by Ashkin optical tweezers have demonstrated their ability and versatility as a non-invasive tool for micromanipulation. One of the most useful additions to the basic optical tweezers system is micro-Raman spectroscopy, which permits highly sensitive analysis of single cells or particles. We report on the development of a dual laser system combining two spatial light modulators to holographically manipulate multiple traps (at 1064nm) whilst undertaking Raman spectroscopy using a 532nm laser. We can thus simultaneously trap multiple particles and record their Raman spectra, without perturbing the trapping system. The dual beam system is built around micro-fluidic channels where crystallisation of calcium carbonate occurs on polymethylmethacrylate (PMMA) beads. The setup is designed to simulate at a microscopic level the reactions that occur on items in a dishwasher, where permanent filming of calcium carbonate on drinking glasses is a problem. Our system allows us to monitor crystal growth on trapped particles in which the Raman spectrum and changes in movement of the bead are recorded. Due to the expected low level of crystallisation on the bead surfaces this allows us to obtain results quickly and with high sensitivity. The long term goal is to study the development of filming on samples in-situ with the microfl.uidic system acting as a model dishwasher.

Lawton, Penelope F.; Saunter, Christopher D.; Girkin, John M.

2014-03-01

324

[Laser flash photolysis, EPR and Raman studies of liquids at elevated pressures  

SciTech Connect

The proposed research will solve a number of analytical chemical problems in solutions with measurement techniques that benefit from the use of elevated hydrostatic pressures: stopped-flow spectrophotometry (Gd[sup 3+] + L(ligand), [RuL[sub 5]H[sub 2]O][sup 2+], laser flash photolysis of Mo(CO)[sub 6] + L, flash photolysis of binuclear metalloproteins), EPR spectroscopy (Gd[sup 3+] ion-exchanged into ETS-10 and ETAS-10 molecular sieves), laser flash photolysis kinetic studies of Mo(CO)[sub 6]-2,2'-bipyridine, and electrochemical studies of metalloporphyrins using resonance Raman spectroscopy.

Eyring, E.M.

1992-01-01

325

[Laser flash photolysis, EPR and Raman studies of liquids at elevated pressures  

SciTech Connect

The proposed research will solve a number of analytical chemical problems in solutions with measurement techniques that benefit from the use of elevated hydrostatic pressures: stopped-flow spectrophotometry (Gd{sup 3+} + L(ligand), [RuL{sub 5}H{sub 2}O]{sup 2+}, laser flash photolysis of Mo(CO){sub 6} + L, flash photolysis of binuclear metalloproteins), EPR spectroscopy (Gd{sup 3+} ion-exchanged into ETS-10 and ETAS-10 molecular sieves), laser flash photolysis kinetic studies of Mo(CO){sub 6}-2,2`-bipyridine, and electrochemical studies of metalloporphyrins using resonance Raman spectroscopy.

Eyring, E.M.

1992-10-01

326

An analysis of bivalve larval shell pigments using micro-Raman spectroscopy  

E-print Network

when larvae were reared in waters with different organic signatures. With micro-Raman spectroscopyAn analysis of bivalve larval shell pigments using micro-Raman spectroscopy Christine M. Thompson,a * Elizabeth W. North,a Sheri N. Whiteb and Scott M. Gallagerb Micro-Raman spectroscopy has been used on adult

North, Elizabeth W.

327

Qualitative and quantitative analysis of chlorinated solvents using Raman spectroscopy and machine learning.  

E-print Network

Qualitative and quantitative analysis of chlorinated solvents using Raman spectroscopy and machine is the identification of solvents into chlorinated or non-chlorinated. In this work we have used Raman spectroscopy. Keywords: Raman spectroscopy, hazardous materials, chlorinated solvents, non-chlorinated solvents

Madden, Michael

328

TEMPERATURE-DEPENDENT RAMAN SPECTROSCOPY OF FULLERENE AND CARBORANE NANOCAR WHEELS  

E-print Network

TEMPERATURE-DEPENDENT RAMAN SPECTROSCOPY OF FULLERENE AND CARBORANE NANOCAR WHEELS B. Shih1,2 , C. Raman spectroscopy is used to study the spinning and sliding behavior of the wheels on different-Dependent Raman Spectroscopy of Fullerene Nanocar Wheels Acknowledgement This material is based upon work

Mellor-Crummey, John

329

Orientational disorder in plastic molecular crystals Infrared and Raman spectroscopy of internal modes  

E-print Network

169 Orientational disorder in plastic molecular crystals III. 2014 Infrared and Raman spectroscopy) Résumé. 2014 La spectroscopie Raman et infrarouge des modes internes dans les cristaux moléculaires à infrared and Raman spectroscopy have been used to probe the rotational dynamics of the molecules

Paris-Sud XI, Université de

330

Mode-Selective Surface-Enhanced Raman Spectroscopy Using Nanofabricated Plasmonic Dipole Antennas  

E-print Network

Mode-Selective Surface-Enhanced Raman Spectroscopy Using Nanofabricated Plasmonic Dipole Antennas; ReVised Manuscript ReceiVed: July 2, 2009 Mode-selective surface-enhanced Raman spectroscopy (SERS of this surface- enhanced Raman spectroscopy (SERS) to the single molecule level,2,3 making SERS an ultrasensitive

Floreano, Dario

331

RAMAN SPECTROSCOPY OF MACROSCALE FIBERS COMPRISED OF CARBON NANOTUBES OF DIFFERENT  

E-print Network

RAMAN SPECTROSCOPY OF MACROSCALE FIBERS COMPRISED OF CARBON NANOTUBES OF DIFFERENT LENGTHS UNDER by in situ Raman spectroscopy while changing the values of uniaxial strain. We investigated the stress 2 types of CNTs Raman Spectroscopy and Analysis Wet Spinning Technique[3] Carbon Nanotube (CNT

Mellor-Crummey, John

332

Noninvasive detection of filaggrin gene mutations using Raman spectroscopy  

PubMed Central

Knowledge of the existence of filaggrin (FLG) gene mutations might be helpful for a subclassification of patients with atopic dermatitis (AD) which can be used to introduce individualized treatments. In this work the filaggrin content in the skin is assessed using Raman spectroscopy and the results are compared to FLG genotyping of Mexican-mestizo patients. Results showed that the 2282del4 and R501X mutations present in the European population but absent in people of Asian or African descent are also present in the Mexican-mestizo population. The results also showed that patients with filaggrin gene mutations presented lower filaggrin concentrations measured using the vector correlation of their skin Raman spectra and a fixed spectrum of pure human recombinant filaggrin, these results indicate that Raman spectroscopy may be used as a noninvasive tool to detect FLG gene mutations. PMID:22162825

González, Francisco J.; Valdes-Rodríguez, Rodrigo; Ramírez-Elías, Miguel G.; Castillo-Martínez, Claudio; Saavedra-Alanis, Victor M.; Moncada, Benjamín

2011-01-01

333

Monitoring lignocellulosic bioethanol production processes using Raman spectroscopy.  

PubMed

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

Iversen, Jens A; Ahring, Birgitte K

2014-11-01

334

Micro-Raman spectroscopy of natural and synthetic indigo samples.  

PubMed

In this work indigo samples from three different sources are studied by using Raman spectroscopy: the synthetic pigment and pigments from the woad (Isatis tinctoria) and the indigo plant (Indigofera tinctoria). 21 samples were obtained from 8 suppliers; for each sample 5 Raman spectra were recorded and used for further chemometrical analysis. Principal components analysis (PCA) was performed as data reduction method before applying hierarchical cluster analysis. Linear discriminant analysis (LDA) was implemented as a non-hierarchical supervised pattern recognition method to build a classification model. In order to avoid broad-shaped interferences from the fluorescence background, the influence of 1st and 2nd derivatives on the classification was studied by using cross-validation. Although chemically identical, it is shown that Raman spectroscopy in combination with suitable chemometric methods has the potential to discriminate between synthetic and natural indigo samples. PMID:12625562

Vandenabeele, Peter; Moens, Luc

2003-02-01

335

Raman-spectroscopy-based biosensing for applications in ophthalmology  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

336

Raman-shifted dye laser for water vapor DIAL measurements  

NASA Technical Reports Server (NTRS)

For improved DIAL measurements of water vapor in the upper troposphere or lower stratosphere, narrowband (about 0.03/cm) laser radiation at 720- and 940-nm wavelengths was generated by stimulated Raman scattering (SRS), using the narrow linewidth (about 0.02/cm) output of a Nd:YAG-pumped dye laser. For a hydrogen pressure of 350 psi, the first Stokes conversion efficiencies to 940 nm were 20 percent and 35 percent, when using a conventional and waveguide Raman cell, respectively. The linewidth of the first Stokes line at high cell pressures, and the inferred collisional broadening coefficients, agree well with those previously measured in spontaneous Raman scattering.

Grossmann, B. E.; Singh, U. N.; Cotnoir, L. J.; Wilkerson, T. D.; Higdon, N. S.; Browell, E. V.

1987-01-01

337

Next generation hazard detection via ultrafast coherent anti-Stokes Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

Brady, John J.; Pellegrino, Paul M.

2013-05-01

338

Raman spectroscopy of nerve fibers. A study of membrane lipids under steady state conditions.  

PubMed Central

The molecular structures of different nerve fibers kept in good physiological conditions were studied by laser Raman spectroscopy. For myelinated nerves like the rat sciatic nerve, the Raman spectrum is dominated by bands due to the lipid component of the myelin sheath. The temperature dependence of these bands does not reveal any thermotropic phase transition between 0 and 40 degrees C. There is, however, with temperature, a linear increase in the intermolecular disorder that is accompanied by an increase in the number of gauche bonds of the phospholipid acyl chains. For unmyelinated nerves such as the lobster leg nerve, the C-H stretching region of the Raman spectrum is covered by bands arising from the protein component of the axoplasm. However, for the garfish olfactory nerve that has a high density of excitable membranes, phospholipid bands are observed and can be used as intrinsic structural probes of the excitable membranes. The relative intensity of these bands is also temperature dependent. PMID:3978206

Pézolet, M; Georgescauld, D

1985-01-01

339

Interference Effects in Resonance Raman Spectroscopy Dr. Lasse Jensen  

E-print Network

Interference Effects in Resonance Raman Spectroscopy Dr. Lasse Jensen Assistant Professor a possibility that interference effects may occur. Interference can be constructive and result in an increased/TCNE complex two overlapping CT excitations causes interference effects that change relative peak intensities

Bjørnstad, Ottar Nordal

340

Recent progress in dynamical spectroscopy of Raman light scattering  

Microsoft Academic Search

The physical bases and some features are presented of the different methods of time-resolved Raman spectroscopy, and also different variants of their realization. The concrete results of the studies are discussed with a large number of examples, including problems of the course of a number of photochemical and photophysical processes and of the structure of intermediate and final products formed

Yakov S Bobovich

1992-01-01

341

Raman spectroscopy on isolated single wall carbon nanotubes  

Microsoft Academic Search

A review is presented on the resonance Raman spectra from one isolated single wall carbon nanotube. The reasons why it is possible to observe the spectrum from only one nanotube are given and the important structural information that is provided by single nanotube spectroscopy is discussed. Emphasis is given to the new physics revealed by the various phonon features found

M. S. Dresselhaus; G. Dresselhaus; A. Jorio; A. G. Souza Filho; R. Saito

2002-01-01

342

Advances in Raman spectroscopy for explosive identification in aviation security  

Microsoft Academic Search

In the operational airport environment, the rapid identification of potentially hazardous materials such as improvised explosive devices, chemical warfare agents and flammable and explosive liquids is increasingly critical. Peroxide-based explosives pose a particularly insidious threat because they can be made from commonly available and relatively innocuous household chemicals, such as bleach and hydrogen peroxide. Raman spectroscopy has been validated as

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

2007-01-01

343

Broadband 308 nm vibrational Raman spectroscopy of gaseous species using a potassium hydrogen phthalate liquid filter and polarization fluorescence suppression.  

PubMed

Broadband XeCl excimer lasers operating at 308 nm are not currently used in the field of gas phase vibrational Raman spectroscopy (VRS). An explanation as to why alternative wavelengths, and in particular tuneable, narrowband lasers are currently preferred for gas phase VRS is presented in addition to demonstrating a setup which makes the XeCl laser a viable alternative when considering excitation sources for VRS. A solution of potassium hydrogen phthalate is shown to be a practical low-pass liquid filter and to reduce substantially the effects of Rayleigh scattering on collected Raman spectra. The use of a commercial beam polarizer is also shown to be effective in suppressing background fluorescence that otherwise necessitates the use of expensive tuneable, narrowband lasers when performing VRS with sources of background fluorescence. Finally, an unconventional excitation beam arrangement is shown to produce viable Raman spectra from which species concentrations and distributions can be determined. PMID:20113082

Saunders, J E A; Davy, M H

2010-01-01

344

Measurement of diabetic sugar concentration in human blood using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

This study demonstrates the use of Raman spectroscopy for the direct measurement of diabetic sugar in human blood using 532 nm laser system. Raman spectra were collected from whole blood drawn from 21 individuals. We have elicited a reliable glucose signature in diabetic patients, and measured glucose levels in blood serum of normal, healthy diabetic and diabetic patients with other malignancies like cancer and hepatitis. Quantitative predictions of glucose spectra illustrate the predictions based on molecular information carried by the Raman light in highly light-scattering and absorbing media. Raman spectrum peaks for diabetic blood serum are observed at 1168, 1531, 1463, 1021 cm-1 with intensity level 17000 to 18500 pixels attributed to carbohydrates, proteins, lipids, collagen, and skeletal C-C stretch of lipids acyl chains. Raman spectra for normal, diabetic patients having cancer and hepatitis were also recorded. This in vitro glucose monitoring methodology will lead in vivo noninvasive on-line monitoring having painless and at the same time the data will be displayed on-line and in real time. The measured Raman peaks provides detailed bio-chemical fingerprint of the sample and could confer diagnostic benefit in a clinical setting.

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

2012-06-01

345

Diagnosis of atherosclerosis in human carotid artery by FT-Raman spectroscopy: Principal Components Analysis algorithm  

NASA Astrophysics Data System (ADS)

FT- Raman Spectroscopy (FT-Raman) could allow identification and evaluation of human atherosclerotic lesions. A Raman spectrum can provide biochemical information of arteries which can help identifying the disease status and evolution. In this study, it is shown the results of FT-Raman for identification of human carotid arteries in vitro. Fragments of human carotid arteries were analyzed using a FT-Raman spectrometer with a Nd:YAG laser at 1064nm operating at an excitation power of 300mW. Spectra were obtained with 250 scans and spectral resolution of 4 cm-1. Each collection time was approximately 8 min. A total of 75 carotid fragments were spectroscopically scanned and FT-Raman results were compared with histopathology. Principal Components Analysis (PCA) was used to model an algorithm for tissue classification into three categories: normal, atherosclerotic plaque without calcification and atherosclerotic plaque with calcification. Non-atherosclerotic (normal) artery, atherosclerotic plaque and calcified plaque exhibit different spectral signatures related to biochemicals presented in each tissue type, such as, bands of collagen and elastin (proteins), cholesterol and its esters and calcium hydroxyapatite and carbonate apatite respectively. Results show that there is 96% match between classifications based on PCA algorithm and histopathology. The diagnostic applied over all 75 samples had sensitivity and specificity of about 89% and 100%, respectively, for atherosclerotic plaque and 100% and 98% for calcified plaque.

Nogueira, Grazielle V.; Silveira, Landulfo, Jr.; Martin, Airton A.; Zangaro, Renato A.; Pacheco, Marcos T.; Chavantes, Maria C.; Zampieri, Marcelo; Pasqualucci, Carlos A. G.

2004-07-01

346

Raman spectroscopy of the ?1 N-H stretch fundamental in isocyanic acid (HNCO): State mixing probed by photoacoustic spectroscopy and by photodissociation of vibrationally excited states  

NASA Astrophysics Data System (ADS)

We report the first gas-phase Raman spectrum of isocyanic acid. Using stimulated Raman excitation (SRE) to prepare vibrationally excited states, we detect transitions by both photoacoustic Raman spectroscopy (PARS) and action spectroscopy. In this paper we present results on the ?1 N-H stretch fundamental, leaving the spectra of the N-C-O symmetric and antisymmetric stretch modes for a separate publication. The Raman spectrum shows extensive state mixing in the ?1 fundamental, in agreement with previous infrared work. Measurement of the effective b-axis rotational constants for different mixed vibrational states in this near-prolate symmetric top limits the number of candidates for perturbing states and shows which vibrational modes participate. Double resonance photodissociation further probes the vibrational spectroscopy of isocyanic acid. The scheme is first to prepare a vibrationally excited state by SRE, then photodissociate only the molecules prepared in the first step, and finally probe the decomposition products by laser-induced fluorescence (LIF). An action spectrum, obtained by scanning the vibrational excitation laser (Stokes) wavelength with the photolysis laser wavelength fixed and the probe laser tuned to a LIF transition in one of the photofragments, is the key to unraveling the spectroscopy. The intensity differences between PARS and action spectrum transitions reveal the vibrational state mixing and provide the Franck-Condon factors for transitions to the excited electronic state.

Brown, Steven S.; Berghout, H. Laine; Crim, F. Fleming

1997-04-01

347

Raman spectroscopy and oral exfoliative cytology  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

348

Determination of octane numbers and Reid vapor pressure in commercial gasoline using dispersive fiber-optic Raman spectroscopy  

Microsoft Academic Search

Dispersive fiber-optic Raman spectroscopy utilizing CCD detection and near-IR DBR diode laser excitation is used to remotely analyze 205 petroleum fuels of varying composition for pump octane number, motor octane number (MON), research octane number (RON), and Reid vapor pressure (RVP). Partial least squares regression analysis in tandem with several preprocessing techniques was used to model pump octane, MON, RON,

Philip E. Flecher; William T. Welch; Sacharia Albin; John B. Cooper

1997-01-01

349

Influence of motional narrowing on the measurability of hydrogen concentration by coherent anti-Stokes Raman spectroscopy  

Microsoft Academic Search

This study was made for measurement of hydrogen concentration in gas mixtures by coherent anti-Stokes Raman spectroscopy (CARS) with the aim of devising a technique for the detection of hydrogen-released from metals and insulating liquids exposed to a variety of external agencies. It has been found experimentally that under the fixed parameters of resonance biharmonic laser pump (BLP) the CARS

G. M. Mikheev; T. N. Mogileva

1999-01-01

350

Raman Spectroscopy and the Raman Microprobe: Valuable new tools for Characterizing Wood and Wood Pulp Fibers  

Microsoft Academic Search

A brief overview of Raman spectroscopy and the photon scattering phenomena which underly it is presented, together with the rationale for applying the methodology to the study of lignocellulosics. The sequence of studies undertaken at The Institute of Paper Chemistry to apply the methods to investigation of celluloses, chemical pulps, wood and high yield fibers are then reviewed.The program began

R. H. Atalla

1987-01-01

351

Noninvasive fluorescence and Raman spectroscopic analysis of laser welded aorta and skin tissue  

NASA Astrophysics Data System (ADS)

Laser tissue welding involves the denaturing and partial renaturing of collagen and elastin. Tissues welded with NIR lasers tuned to the 1455 nm water absorption band have demonstrated high tensile strength with minimal collateral damage. To better understand the welding process, welded tissue samples were investigated using fluorescence imaging and Raman spectroscopy. As part of this study, human aorta, and porcine aorta and skin, specimens were investigated. Emission and excitation/emission wavelengths corresponding to tryptophan and collagen emission and slightly weaker emission for wavelengths corresponding to elastin emission. The inner surface an cross-section images of the aortic specimens exhibited a very high degree of uniformity with no indication of the presence of a weld. The Raman spectra from the aortic specimens at the weld site and a few mm away form the weld were very similar. This work indicates the emission and Raman properties of the collagen helix after welding are very similar to native collagen tissue.

Katz, Alvin; Gayen, Tapan K.; Minko, Glenn; Alimova, Alexandra; Savage, Howard E.; McCormick, Steven A.; Alfano, Robert R.

2002-05-01

352

Phase structure, composition and orientation of PC\\/PSAN blends studied by Raman spectroscopy, confocal Raman imaging spectroscopy and polarised PA-FTIR spectroscopy  

Microsoft Academic Search

Polycarbonate(PC)\\/ poly(styrene-co-acrylonitrile)(PSAN) blends were investigated by Raman and confocal Raman imaging spectroscopy, revealing the existence of two-phase (PC-rich and PSAN-rich) microdomain structure. This structure is coarser in blends with comparable component contents. During cold drawing the microdomains are strongly extended. As follows from polarised photoacoustic FTIR spectroscopy, a substantial orientation of PC chains occurs, as opposed to PSAN chains which

P Schmidt; J Kola???k; F Lednický; J Dybal; J. M Lagarón; J. M Pastor

2000-01-01

353

Distinguishing Cancerous Liver Cells Using Surface-Enhanced Raman Spectroscopy.  

PubMed

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

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

2014-11-28

354

Raman spectroscopy of Bacillus thuringiensis physiology and inactivation  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

355

Raman spectroscopy for the characterization of algal cells  

NASA Astrophysics Data System (ADS)

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

Samek, Ota; Jonáš, Alexandr; Pilát, Zden?k; Zemánek, Pavel; Nedbal, Ladislav; T?íska, Jan; Kotas, Petr; Trtílek, Martin

2010-12-01

356

Exploring Raman spectroscopy for the evaluation of glaucomatous retinal changes  

NASA Astrophysics Data System (ADS)

Glaucoma is a chronic neurodegenerative disease characterized by apoptosis of retinal ganglion cells and subsequent loss of visual function. Early detection of glaucoma is critical for the prevention of permanent structural damage and irreversible vision loss. Raman spectroscopy is a technique that provides rapid biochemical characterization of tissues in a nondestructive and noninvasive fashion. In this study, we explored the potential of using Raman spectroscopy for detection of glaucomatous changes in vitro. Raman spectroscopic imaging was conducted on retinal tissues of dogs with hereditary glaucoma and healthy control dogs. The Raman spectra were subjected to multivariate discriminant analysis with a support vector machine algorithm, and a classification model was developed to differentiate disease tissues versus healthy tissues. Spectroscopic analysis of 105 retinal ganglion cells (RGCs) from glaucomatous dogs and 267 RGCs from healthy dogs revealed spectroscopic markers that differentiated glaucomatous specimens from healthy controls. Furthermore, the multivariate discriminant model differentiated healthy samples and glaucomatous samples with good accuracy [healthy 89.5% and glaucomatous 97.6% for the same breed (Basset Hounds); and healthy 85.0% and glaucomatous 85.5% for different breeds (Beagles versus Basset Hounds)]. Raman spectroscopic screening can be used for in vitro detection of glaucomatous changes in retinal tissue with a high specificity.

Wang, Qi; Grozdanic, Sinisa D.; Harper, Matthew M.; Hamouche, Nicolas; Kecova, Helga; Lazic, Tatjana; Yu, Chenxu

2011-10-01

357

Raman spectroscopy and microspectrophotometry of reactive dyes on cotton fibres: analysis and detection limits.  

PubMed

A collaborative study on Raman spectroscopy and microspectrophotometry (MSP) was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on different dyed cotton fabrics. The detection limits of the two methods were tested on two cotton sets with a dye concentration ranging from 0.5 to 0.005% (w/w). This survey shows that it is possible to detect the presence of dye in fibres with concentrations below that detectable by the traditional methods of light microscopy and microspectrophotometry (MSP). The MSP detection limit for the dyes used in this study was found to be a concentration of 0.5% (w/w). At this concentration, the fibres appear colourless with light microscopy. Raman spectroscopy clearly shows a higher potential to detect concentrations of dyes as low as 0.05% for the yellow dye RY145 and 0.005% for the blue dye RB221. This detection limit was found to depend both on the chemical composition of the dye itself and on the analytical conditions, particularly the laser wavelength. Furthermore, analysis of binary mixtures of dyes showed that while the minor dye was detected at 1.5% (w/w) (30% of the total dye concentration) using microspectrophotometry, it was detected at a level as low as 0.05% (w/w) (10% of the total dye concentration) using Raman spectroscopy. This work also highlights the importance of a flexible Raman instrument equipped with several lasers at different wavelengths for the analysis of dyed fibres. The operator and the set up of the analytical conditions are also of prime importance in order to obtain high quality spectra. Changing the laser wavelength is important to detect different dyes in a mixture. PMID:22727570

Massonnet, G; Buzzini, P; Monard, F; Jochem, G; Fido, L; Bell, S; Stauber, M; Coyle, T; Roux, C; Hemmings, J; Leijenhorst, H; Van Zanten, Z; Wiggins, K; Smith, C; Chabli, S; Sauneuf, T; Rosengarten, A; Meile, C; Ketterer, S; Blumer, A

2012-10-10

358

Raman scattering spectroscopy for explosives identification  

Microsoft Academic Search

of traces of explosives at any line-of-sight (LOS) orientation rela- tive to the sensor's laser source. We have successfully completed a remote scan field prototype system for detecting and identify- ing sub-milligram quantities of explosives at distances of up to 30m. 7 Scattered light from a pulsed green laser (532nm), reflected from the surface analyzed, is optically collected and analyzed

Lev Nagli; Michael Gaft

2007-01-01

359

Raman spectroscopy on simple molecular systems at very high density  

SciTech Connect

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

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

1988-01-01

360

Quantitative polarized Raman spectroscopy in highly turbid bone tissue  

NASA Astrophysics Data System (ADS)

Polarized Raman spectroscopy allows measurement of molecular orientation and composition and is widely used in the study of polymer systems. Here, we extend the technique to the extraction of quantitative orientation information from bone tissue, which is optically thick and highly turbid. We discuss multiple scattering effects in tissue and show that repeated measurements using a series of objectives of differing numerical apertures can be employed to assess the contributions of sample turbidity and depth of field on polarized Raman measurements. A high numerical aperture objective minimizes the systematic errors introduced by multiple scattering. We test and validate the use of polarized Raman spectroscopy using wild-type and genetically modified (oim/oim model of osteogenesis imperfecta) murine bones. Mineral orientation distribution functions show that mineral crystallites are not as well aligned (p<0.05) in oim/oim bones (28+/-3 deg) compared to wild-type bones (22+/-3 deg), in agreement with small-angle X-ray scattering results. In wild-type mice, backbone carbonyl orientation is 76+/-2 deg and in oim/oim mice, it is 72+/-4 deg (p>0.05). We provide evidence that simultaneous quantitative measurements of mineral and collagen orientations on intact bone specimens are possible using polarized Raman spectroscopy.

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

2010-05-01

361

Hydrogen bonding in aqueous ethanol solutions studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The results of Raman spectroscopy research of aqueous ethanol solutions with various mixing ratios are presented. The analysis of the behavior of Raman spectra with changes in ethanol concentration from 0 to pure ethanol is given. The analysis of contour of stretching OH-band provided information about changes in hydrogen bonding along with increases in ethanol concentration. Obtained results showed that the maximum strength of H-bonding in aqueous ethanol solution corresponded to an ethanol concentration of 15...20 % w/w. The observed strengthening of H-bonding strongly supports the hypothesis of clathrate-like structures. These results were supported by application of MCR-ALS method.

Dolenko, Tatiana; Burikov, Sergey; Hojo, Masashi; Patsaeva, Svetlana; Yuzhakov, Victor

2010-11-01

362

Background-free stimulated Raman spectroscopy and microscopy.  

PubMed

We propose a three-color, double-modulation scheme for the background-free detection of stimulated Raman scattering (SRS). We call the scheme stimulated Raman gain and opposite loss detection (SRGOLD). It exploits the symmetric nature of potential parasitic signals (cross phase modulation, two-photon absorption, and thermal effects) to the end of suppressing them. Conversely, the antisymmetric nature of SRS provides for a twofold increase in the magnitude of the SRS signal. We experimentally demonstrate SRGOLD spectroscopy and microscopy on test samples as well as on mice skin samples. PMID:24580595

Berto, Pascal; Andresen, Esben Ravn; Rigneault, Hervé

2014-02-01

363

Raman spectroscopy of glassy carbon up to 60 GPa  

NASA Astrophysics Data System (ADS)

In the present work in experiments in a diamond anvil cell at room temperature we studied the behavior of glassy carbon under high pressure up to 60 GPa by means of in situ Raman spectroscopy. Raman bands typical for glassy carbon were clearly observed in the entire pressure interval. We did not see any noticeable changes in the type of chemical bonding in glassy carbon up to the highest pressure reached. The yield strength of the material under confining pressure was found to be maximum of about 7 GPa, inconsiderably higher than that measured at ambient pressure (1.4 GPa on literature data).

Solopova, N. A.; Dubrovinskaia, N.; Dubrovinsky, L.

2013-03-01

364

High-pressure Raman spectroscopy of Re3N crystals  

NASA Astrophysics Data System (ADS)

Well-crystallized plate-like Re3N crystals were synthesized through a high-pressure solid-state metathesis (HPSSM) reaction in large volume press (LVP) at 14 GPa and 1973 K. The vibrational properties of Re3N crystals were studied by high-pressure Raman spectroscopy in diamond anvil cell (DAC) up to 20 GPa. The mode-Grüneisen parameters for Raman modes of Re3N were determined experimentally, which were found substantially being larger than previously calculated values.

Jiang, Xiaodong; Lei, Li; Hu, Qiwei; Feng, Zhe Chuan; He, Duanwei

2015-01-01

365

Verifying of endocrine disruptor chemical affect to the mouse testes: can raman spectroscopy support histology study?  

NASA Astrophysics Data System (ADS)

One of suspect environmental endocrine disruptors that affect mouse male reproduction by altering the morphology of Sertoli cells and spermatogenic cells is phthalate. The effects of mono(2-ethylhexyl)phthalate (MEHP), one of metabolites of di(2-ethylhexyl)phthalate , on immature mouse testes in vivo were examined. We have recently shown that MEHP induced Sertoli cells necrosis and spermatogenic cells apoptosis in mice by TUNEL method, F-actin staining, and ultrastructural study, but there is no data for biochemical changing of testes due to those methods could not explore. To verify in detail of it, we conducted Raman spectroscopy study with 785 nm wavelength laser line, 50mW of laser power and 3 minutes of exposure time to analysis the MEHP-treated testicular tissue, which has been fixatived by 4% paraformaldehyde (PFA). Five weeks old (5 w.o) male mice were used in this experiment. As the results, the alterations were observed by Raman spectroscopy that there are significantly differences of DNA, actin filament, type IV collagen and amide I between control group (0 ?M MEHP) and treatment group (100 ?M MEHP). These results significantly support histology staining observation (such as the apoptotic spermatogenic cells which is associated with DNA fragmentation and F-actin disruption) and ultrastructural observation (such as mitochondria rupture and disintegration of nucleus membrane). Raman spectroscopy can be used for 4% PFA-fixatived tissue observation. However, we recommend that Raman spectroscopy may be able to be expanded as an armamentarium not just for the clarification of histology staining and ultrastructural study, but furthermore, it may be as a non-invasion assessment for screening animal tissue toxicity of chemical in future.

Andriana, Bibin B.; Oshima, Yusuke; Takanezawa, Sota; Tay, Tat W.; Rosawati Soeratman, Catherine Linda; Alam, Mohammad S.; Mitsuoka, Hiroki; Zhu, Xiao B.; Suzuki, Toshiaki; Yamamoto, Yuko S.; Tsunekawa, Naoki; Kanai, Yoshiakira; Kurohmaru, Masamichi; Sato, Hidetoshi

2009-02-01

366

Single nanoparticle detection using split-mode microcavity Raman lasers.  

PubMed

Ultrasensitive nanoparticle detection holds great potential for early-stage diagnosis of human diseases and for environmental monitoring. In this work, we report for the first time, to our knowledge, single nanoparticle detection by monitoring the beat frequency of split-mode Raman lasers in high-Q optical microcavities. We first demonstrate this method by controllably transferring single 50-nm-radius nanoparticles to and from the cavity surface using a fiber taper. We then realize real-time detection of single nanoparticles in an aqueous environment, with a record low detection limit of 20 nm in radius, without using additional techniques for laser noise suppression. Because Raman scattering occurs in most materials under practically any pump wavelength, this Raman laser-based sensing method not only removes the need for doping the microcavity with a gain medium but also loosens the requirement of specific wavelength bands for the pump lasers, thus representing a significant step toward practical microlaser sensors. PMID:25267618

Li, Bei-Bei; Clements, William R; Yu, Xiao-Chong; Shi, Kebin; Gong, Qihuang; Xiao, Yun-Feng

2014-10-14

367

Single molecule laser spectroscopy.  

PubMed

In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion. PMID:25156641

Atta, Diaa; Okasha, Ali

2015-01-25

368

Single molecule laser spectroscopy  

NASA Astrophysics Data System (ADS)

In this article, we discussed some single molecule spectroscopy techniques and methods. We have chosen the simplicity in this survey based on our laboratory experience in this field. We concentrated on the imaging by both techniques the wide field and the scanning microscopes. Other imaging enhancements on the technique like extended resolution wide field, the total internal reflection imaging, and its derivatives are also reviewed. In addition to the imaging techniques, some diffusion techniques also are discussed like fluorescence correlation spectroscopy. The related methods like Forester resonance transfer, photo-induced electron transfer and anisotropy (steady state and time decay) are also discussed. In addition, we elucidated some simple details about the theory behind the FCS and its resulting curve fitting. This review is preceded by general introduction and ended with the conclusion.

Atta, Diaa; Okasha, Ali

2015-01-01

369

Raman spectroscopy for quantifying cholesterol in intact coronary artery wall.  

PubMed

The chemical composition of vascular lesions, an important determinant of plaque progression and rupture, can not presently be determined in vivo. Prior studies have shown that Raman spectroscopy can accurately quantify the amounts of major lipid classes and calcium salts in homogenized coronary artery tissue. This study determines how the relative cholesterol content, which is calculated from Raman spectra collected at the luminal surface of an artery, is related to its depth in an intact arterial wall. Raman spectra of human atherosclerotic plaques were measured after thin tissue layers were successively placed on them. From these spectra, relative cholesterol contents were calculated and used to determine how cholesterol signal strength is attenuated by overlaying tissue. Then, intact artery samples (n = 13) were examined spectroscopically, sectioned and stained specifically for cholesterol. Images of these sections were digitized, and image intensities were related to cholesterol content. These cholesterol amounts were weighed appropriately for depth into the tissue and area-integrated for comparison with spectroscopy results. A decaying exponential curve was fit to the layer study data (r2 = 0.97) and showed that approximately 300 microm of tissue attenuates cholesterol signals by 50%. In intact plaques, the spectroscopically-determined cholesterol amounts correlated strongly and linearly with those determined by digital microscopy (r2 = 0.94). With Raman spectroscopy techniques, the cholesterol content of a lesion can be determined by properly accounting for its depth into an arterial wall. Our results suggest that chemical concentrations in an artery wall could be mapped throughout its thickness, possibly by combining Raman spectroscopy methods with other techniques. PMID:9863544

Römer, T J; Brennan, J F; Schut, T C; Wolthuis, R; van den Hoogen, R C; Emeis, J J; van der Laarse, A; Bruschke, A V; Puppels, G J

1998-11-01

370

rotational Raman spectroscopy methods for probing energy thermalisation processes during spin-exchange optical pumping  

NASA Astrophysics Data System (ADS)

Spin-exchange optical pumping (SEOP) has been widely used to produce enhancements in nuclear spin polarisation for hyperpolarised noble gases. However, some key fundamental physical processes underlying SEOP remain poorly understood, particularly in regards to how pump laser energy absorbed during SEOP is thermalised, distributed and dissipated. This study uses in situ ultra-low frequency Raman spectroscopy to probe rotational temperatures of nitrogen buffer gas during optical pumping under conditions of high resonant laser flux and binary Xe/N2 gas mixtures. We compare two methods of collecting the Raman scattering signal from the SEOP cell: a conventional orthogonal arrangement combining intrinsic spatial filtering with the utilisation of the internal baffles of the Raman spectrometer, eliminating probe laser light and Rayleigh scattering, versus a new in-line modular design that uses ultra-narrowband notch filters to remove such unwanted contributions. We report a ~23-fold improvement in detection sensitivity using the in-line module, which leads to faster data acquisition and more accurate real-time monitoring of energy transport processes during optical pumping. The utility of this approach is demonstrated via measurements of the local internal gas temperature (which can greatly exceed the externally measured temperature) as a function of incident laser power and position within the cell.

Newton, Hayley; Walkup, Laura L.; Whiting, Nicholas; West, Linda; Carriere, James; Havermeyer, Frank; Ho, Lawrence; Morris, Peter; Goodson, Boyd M.; Barlow, Michael J.

2014-05-01

371

Combined micro-Fourier transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy of Proterozoic acritarchs: A new approach to Palaeobiology  

Microsoft Academic Search

Micro-scale analytical techniques permit correlation of chemistry with morphology of individual Proterozoic acritarchs (organic-walled microfossils), and thus provide new approaches for elucidating their biological affinities. A combination of micro-Fourier transform infrared (FTIR) spectroscopy and laser micro-Raman spectroscopy was used to investigate the organic structure and composition of individual acritarchs. Well preserved Neoproterozoic acritarchs from the Tanana Formation, Australia (ca. 590–565Ma),

Craig P. Marshall; Emmanuelle J. Javaux; Andrew H. Knoll; Malcolm R. Walter

2005-01-01

372

Fe-Ti-Cr-Oxides in Martian Meteorite EETA79001 Studied by Point-counting Procedure Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

Fe-Ti-Cr-Oxide minerals contain much information about rock petrogenesis and alteration. Among the most important in the petrology of common intrusive and extrusive rocks are those of the FeO-TiO2-Cr2O3 compositional system chromite, ulv spinel-magnetite, and ilmenite-hematite. These minerals retain memories of oxygen fugacity. Their exsolution into companion mineral pairs give constraints on formation temperature and cooling rate. Laser Raman spectroscopy is anticipated to be a powerful technique for characterization of materials on the surface of Mars. A Mars Microbeam Raman Spectrometer (MMRS) is under development. It combines a micro sized laser beam and an automatic point-counting mechanism, and so can detect minor minerals or weak Raman-scattering phases such as Fe- Ti-Cr-oxides in mixtures (rocks & soils), and provide information on grain size and mineral mode. Most Fe-Ti-Cr-oxides produce weaker Raman signals than those from oxyanionic minerals, e.g. carbonates, sulfates, phosphates, and silicates, partly because most of them are intrinsically weaker Raman scatters, and partly because their dark colors limit the penetration depth of the excitation laser beam (visible wavelength) and of the Raman radiation produced. The purpose of this study is to show how well the Fe-Ti-Cr-oxides can be characterized by on-surface planetary exploration using Raman spectroscopy. We studied the basic Raman features of common examples of these minerals using well-characterized individual mineral grains. The knowledge gained was then used to study the Fe-Ti-Cr-oxides in Martian meteorite EETA79001, especially effects of compositional and structural variations on their Raman features.

Wang, Alian; Kuebler, Karla E.; Jolliff, Bradley L.; Haskin, Larry A.

2003-01-01

373

Modern Raman Imaging: Vibrational Spectroscopy on the Micrometer and Nanometer Scales  

NASA Astrophysics Data System (ADS)

Raman microscopes are currently used in various fields of research because they allow for label-free sample investigation. Moreover, the inherently low scattering cross section of Raman spectroscopy, as well as its diffraction-limited lateral resolution, has been overcome by new Raman microscopy techniques. Nonlinear methods such as coherent anti-Stokes Raman spectroscopy and stimulated Raman spectroscopy reduce measurement times and improve z resolution, allowing for three-dimensional spectroscopic imaging of biological samples. Moreover, tip-enhanced Raman spectroscopy, a near-field optical technique that combines scanning-probe microscopy with the enhancement offered by surface-enhanced Raman scattering, enables Raman spectroscopic imaging far below the optical diffraction limit. We cover the theoretical and technical aspects of Raman microscopy and related new imaging techniques and review some very recent applications in graphene research and cell biology.

Opilik, Lothar; Schmid, Thomas; Zenobi, Renato

2013-06-01

374

Classification for breast cancer diagnosis with Raman spectroscopy  

PubMed Central

In order to promote the development of the portable, low-cost and in vivo cancer diagnosis instrument, a miniature laser Raman spectrometer was employed to acquire the conventional Raman spectra for breast cancer detection in this paper. But it is difficult to achieve high discrimination accuracy. Then a novel method of adaptive weight k-local hyperplane (AWKH) is proposed to increase the classification accuracy. AWKH is an extension and improvement of K-local hyperplane distance nearest-neighbor (HKNN). It considers the features weights of the training data in the nearest neighbor selection and local hyperplane construction stage, which resolve the basic shortcoming of HKNN works well only for small values of the nearest-neighbor. Experimental results on Raman spectra of breast tissues in vitro show the proposed method can realize high classification accuracy. PMID:25071976

Li, Qingbo; Gao, Qishuo; Zhang, Guangjun

2014-01-01

375

Optimally shaped narrowband picosecond pulses for femtosecond stimulated Raman spectroscopy.  

PubMed

A comparison between a Fabry-Pérot etalon filter and a conventional grating filter for producing the picosecond (ps) Raman pump pulses for femtosecond stimulated Raman spectroscopy (FSRS) is presented. It is shown that for pulses of equal energy the etalon filter produces Raman signals twice as large as that of the grating filter while suppressing the electronically resonant background signal. The time asymmetric profile of the etalon-generated pulse is shown to be responsible for both of these observations. A theoretical discussion is presented which quantitatively supports this hypothesis. It is concluded that etalons are the ideal method for the generation of narrowband ps pulses for FSRS because of the optical simplicity, efficiency, improved FSRS intensity and reduced backgrounds. PMID:24104042

Hoffman, David P; Valley, David; Ellis, Scott R; Creelman, Mark; Mathies, Richard A

2013-09-01

376

Utilization of chirped laser pulses to measure stimulated Raman scattering of organic liquids in the terahertz regime  

NASA Astrophysics Data System (ADS)

With the present paper, we demonstrate an experimental setup connecting two highly innovative fields of research: stimulated Raman scattering (SRS) spectroscopy and terahertz (THz) spectroscopy of liquids. For this purpose, we use the spectral focusing method allowing us to excite and measure molecular vibrations by chirped laser pulses. With our experimental setup, we apply this method to the THz regime in order to detect the frequency dependence of SRS processes in organic liquids. More specifically, we focus two chirped laser pulses onto the sample to drive molecular vibrations at THz frequencies. Thereby, the time delay between the laser pulses is directly related to the driving frequency. Due to SRS process, an energy transfer between the two laser pulses is established. By detecting the corresponding energy change of only one of the two laser pulses, we are able to observe inverse Raman scattering and stimulated Raman gain scattering as well as the transition between both processes at zero delay time. The peak positions and the line shapes of the measured spectra agree well with literature data obtained by spontaneous Raman scattering spectroscopy and optical heterodyne detection optical Kerr effect spectroscopy. With the present setup, we are able to excite and detect molecular vibrations ranging over two orders of magnitude from 10 THz to ultra-low frequencies at 100 GHz.

Funkner, Stefan; Saito, Katsuya; Niehues, Gudrun; Yazawa, Yoshiki; Furuya, Takashi; Yamamoto, Kohji; Tani, Masahiko

2014-07-01

377

In-situ identification of meat from different animal species by shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

The identification of food products and the detection of adulteration are of global interest for food safety and quality control. We present a non-invasive in-situ approach for the differentiation of meat from selected animal species using microsystem diode laser based shifted excitation Raman difference spectroscopy (SERDS) at 671 nm and 785 nm. In that way, the fingerprint Raman spectra can be used for identification without a disturbing fluorescence background masking Raman signals often occurring in the investigation of biological samples. Two miniaturized SERDS measurement heads including the diode laser and all optical elements are fiber-optically coupled to compact laboratory spectrometers. To realize two slightly shifted excitation wavelengths necessary for SERDS the 671 nm laser (spectral shift: 0.7 nm, optical power: 50 mW) comprises two separate laser cavities each with a volume Bragg grating for frequency selection whereas the 785 nm light source (spectral shift: 0.5 nm, optical power: 110 mW) is a distributed feedback laser. For our investigations we chose the most consumed meat types in the US and Europe, i.e. chicken and turkey as white meat as well as pork and beef as red meat species. The applied optical powers were sufficient to detect meat Raman spectra with integration times of 10 seconds pointing out the ability for a rapid discrimination of meat samples. Principal components analysis was applied to the SERDS spectra to reveal spectral differences between the animals suitable for their identification. The results will be discussed with respect to specific characteristics of the analyzed meat species.

Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

2012-05-01

378

Raman scattering of laser radiation in magnetoactive plasma  

NASA Astrophysics Data System (ADS)

Raman scattering in a subcritical plasma is simulated numerically for the case where the laser radiation propagates transversely to an external magnetic field. It is shown that, in the linear stage of Raman instability, the magnetic field decreases the instability growth rate for forward scattering and increases it for backward scattering. As the value of the magnetic field increases, the stochastic heating of plasma electrons is enhanced in the region of backscattering.

Krasovitskiy, V. B.; Turikov, V. A.

2012-12-01

379

Controllable continuous-wave Nd:YVO? self-Raman lasers using intracavity adaptive optics.  

PubMed

A controllable self-Raman laser using an adaptive optics (AO)-based control loop featuring an intracavity deformable mirror is reported. This method has the potential to alleviate thermal lensing within the Raman and laser gain media, and enable solid-state Raman lasers to reach new power levels. A proof-of-concept experiment using a Nd:YVO4 self-Raman laser and resulting in 18% enhancement of the first Stokes output power is reported. Moreover, wavelength selection between two Raman laser outputs (?=1109 and 1176 nm) emanating from the 379 and 893 cm(-1) Raman shifts of YVO4, respectively, was achieved using this AO technique. PMID:25121868

Li, Ran; Griffith, Mike; Laycock, Leslie; Lubeigt, Walter

2014-08-15

380

Raman spectra of high- ? dielectric layers investigated with micro-Raman spectroscopy comparison with silicon dioxide.  

PubMed

Three samples with dielectric layers from high- ? dielectrics, hafnium oxide, gadolinium-silicon oxide, and lanthanum-lutetium oxide on silicon substrate were studied by Raman spectroscopy. The results obtained for high- ? dielectrics were compared with spectra recorded for silicon dioxide. Raman spectra suggest the similarity of gadolinium-silicon oxide and lanthanum-lutetium oxide to the bulk nondensified silicon dioxide. The temperature treatment of hafnium oxide shows the evolution of the structure of this material. Raman spectra recorded for as-deposited hafnium oxide are similar to the results obtained for silicon dioxide layer. After thermal treatment especially at higher temperatures (600°C and above), the structure of hafnium oxide becomes similar to the bulk non-densified silicon dioxide. PMID:24072982

Borowicz, P; Taube, A; Rzodkiewicz, W; Latek, M; Giera?towska, S

2013-01-01

381

Comparative Study of Raman Spectroscopy in Graphene and MoS2-type Transition Metal Dichalcogenides.  

PubMed

Conspectus Raman spectroscopy is one of the most powerful experimental tools to study graphene, since it provides much useful information for sample characterization. In this Account, we show that this technique is also convenient to study other bidimensional materials beyond graphene, and we will focus on the semiconducting transition metal dichalcogenides (MX2), specifically on MoS2 and WS2. We start by comparing the atomic structure of graphene and 2H-MX2 as a function of the number of layers in the sample. The first-order Raman active modes of each material can be predicted on the basis of their corresponding point-group symmetries. We show the analogies between graphene and 2H-MX2 in their Raman spectra. Using several excitation wavelengths in the visible range, we analyze the first- and second-order features presented by each material. These are the E2g and 2TO(K) bands in graphene (also known as the G and 2D bands, respectively) and the A1', E', and 2LA(M) bands in 2H MX2. The double-resonance processes that originate the second-order bands are different for both systems, and we will discuss them in terms of the different electronic structure and phonon dispersion curves presented by each compound. According to the electronic structure of graphene, which is a zero band gap semiconductor, the Raman spectrum is resonant for all the excitation wavelengths. Moreover, due to the linear behavior of the electronic dispersion near the K point, the double-resonance bands of graphene are dispersive, since their frequencies vary when we change the laser energy used for the sample excitation. In contrast, the semiconducting MX2 materials present an excitonic resonance at the direct gap, and consequently, the double-resonance Raman bands of MX2 are not dispersive, and only their intensities depend on the laser energy. In this sense, resonant Raman scattering experiments performed in transition metal dichalcogenides using a wide range of excitation energies can provide information about the electronic structure of these materials, which is complementary to other optical spectroscopies, such as absorption or photoluminescence. Raman spectroscopy can also be useful to address disorder in MX2 samples in a similar way as it is used in graphene. Both materials exhibit additional Raman features associated with phonons within the interior of the Brillouin zone that are activated by the presence of defects and that are not observed in pristine samples. Such is the case of the well-known D band of graphene. MX2 samples present analogous features that are clearly observed at specific excitation energies. The origins of these double-resonance Raman bands in MX2 are still subjects of current research. Finally, we discuss the suitability of Raman spectroscopy as a strain or doping sensor. Such applications of Raman spectroscopy are being extensively studied in the case of graphene, and considering its structural analogies with MX2 systems, we show how this technique can also be used to provide strain/doping information for transition metal dichalcogenides. PMID:25490518

Pimenta, Marcos A; Del Corro, Elena; Carvalho, Bruno R; Fantini, Cristiano; Malard, Leandro M

2014-12-01

382

Quantitative detection of astaxanthin and cantaxanthin in Atlantic salmon by resonance Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Two major carotenoids species found in salmonids muscle tissues are astaxanthin and cantaxanthin. They are taken up from fish food and are responsible for the attractive red-orange color of salmon filet. Since carotenoids are powerful antioxidants and biomarkers of nutrient consumption, they are thought to indicate fish health and resistance to diseases in fish farm environments. Therefore, a rapid, accurate, quantitative optical technique for measuring carotenoid content in salmon tissues is of economic interest. We demonstrate the possibility of using fast, selective, quantitative detection of astaxanthin and cantaxanthin in salmon muscle tissues, employing resonance Raman spectroscopy. Analyzing strong Raman signals originating from the carbon-carbon double bond stretch vibrations of the carotenoid molecules under blue laser excitation, we are able to characterize quantitatively the concentrations of carotenoids in salmon muscle tissue. To validate the technique, we compared Raman data with absorption measurements of carotenoid extracts in acetone. A close correspondence was observed in absorption spectra for tissue extract in acetone and a pure astaxanthin solution. Raman results show a linear dependence between Raman and absorption data. The proposed technique holds promise as a method of rapid screening of carotenoid levels in fish muscle tissues and may be attractive for the fish farm industry to assess the dietary status of salmon, risk for infective diseases, and product quality control.

Ermakov, Igor V.; Ermakova, Maia R.; Gellermann, Werner

2006-02-01

383

Detection and characterization of stomach cancer and atrophic gastritis with fluorescence and Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In this paper, we attempt to find a valid method to distinguish gastric cancer and atrophic gastritis. Auto-fluorescence and Raman spectroscopy of laser induced (514.5 nm and 488.0 nm) was measured. The serum spectrum is different between normal and cancer. Average value of diagnosis parameter for normal serum, red shift is less than 12 nm and Raman relative intensity of peak C by 514.5 nm excited is stronger than that of 488.0 nm. To gastric cancer, its red shift of average is bigger than 12 nm and relative intensity of Raman peak C by 514.5 nm excited is weaker than that by 488.0 nm. To atrophic gastritis, the distribution state of Raman peaks is similar with normal serum and auto-fluorescence spectrum's shape is similar to that of gastric cancer. Its average Raman peak red shift is bigger than 12 nm and the relative intensity of peak C by 514.5 excited is stronger than that of by 488.0. We considered it as a criterion and got an accuracy of 85.6% for diagnosis of gastric cancer compared with the result of clinical diagnosis.

Li, Xiaozhou; Lin, Junxiu; Jia, Chunde; Wang, Rong

2003-12-01

384

Shifted excitation Raman difference spectroscopy at multiple wavelengths for in-situ meat species differentiation  

NASA Astrophysics Data System (ADS)

Two miniaturized Raman measurement heads containing microsystem diode lasers emitting at 783 and 671 nm suitable for shifted excitation Raman difference spectroscopy (SERDS) were applied for the non-invasive in situ differentiation of selected meat species. This allows using the fingerprint characteristics of Raman spectra without a disturbing fluorescence background. At 783 nm, two emission lines with a spectral shift of 0.5 nm (7 cm-1) and optical powers of up to 110 mW were realized. For 671 nm excitation, the spectral shift amounts to 0.6 nm (12 cm-1) and optical powers of up to 40 mW were obtained. In both cases, meat Raman spectra could be recorded with integration times of 10 s. The investigations were carried out using selected cuts from the most commonly consumed meat species in the US and Europe, i.e. beef, pork, chicken, and turkey. A principal components analysis of the SERDS spectra revealed a clear separation of the meat species into four distinct groups for both excitation wavelengths. This classification is based on the myoglobin content and gradual differences of protein Raman band intensities and positions. The results demonstrate the potential of SERDS as rapid and non-destructive screening method for the discrimination of selected meat species.

Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

2012-09-01

385

Raman Spectroscopy-Compatible Inactivation Method for Pathogenic Endospores?  

PubMed Central

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

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

2010-01-01

386

Using Raman Spectroscopy to Study Diamond Thin Films  

NASA Astrophysics Data System (ADS)

Diamond thin films (DTF), due to their extreme hardness, low electrical conductivity and chemical inertness, have various applications in semiconductor and machining industry. DTF strengthen machining and cutting tools that demand more precision and resist chemical corrosions as electrodes. The DTF created in this investigation were produced using a hybrid physical-chemical vapor deposition process in an electron cyclotron resonance sputter source. The samples formed can be amorphous carbon, graphite, or diamond. A method to test whether the sputter source successfully created diamond is Raman spectroscopy, a non-invasive technique that utilizes photo excitation and Raman scattering of monochromatic light. A sharp peak at 1332 inverse cm indicates the signature Raman shift of the sp3 C-C bond of pure diamond in these spectra. Graphite and amorphous carbon have their signature peaks near 1580 inverse cm and 1343 inverse cm. The technique is used to study wafer quality as a function of plasma parameters. Results will ultimately be benchmarked against Raman spectroscopy system at The College of New Jersey, and more samples will be produced to ensure the uniformity of the sputter source.

Lin, Yi-Hsuan; Zwicker, Andrew

2011-11-01

387

Discrimination of serum Raman spectroscopy between normal and colorectal cancer  

NASA Astrophysics Data System (ADS)

Raman spectroscopy of tissues has been widely studied for the diagnosis of various cancers, but biofluids were seldom used as the analyte because of the low concentration. Herein, serum of 30 normal people, 46 colon cancer, and 44 rectum cancer patients were measured Raman spectra and analyzed. The information of Raman peaks (intensity and width) and that of the fluorescence background (baseline function coefficients) were selected as parameters for statistical analysis. Principal component regression (PCR) and partial least square regression (PLSR) were used on the selected parameters separately to see the performance of the parameters. PCR performed better than PLSR in our spectral data. Then linear discriminant analysis (LDA) was used on the principal components (PCs) of the two regression method on the selected parameters, and a diagnostic accuracy of 88% and 83% were obtained. The conclusion is that the selected features can maintain the information of original spectra well and Raman spectroscopy of serum has the potential for the diagnosis of colorectal cancer.

Li, Xiaozhou; Yang, Tianyue; Yu, Ting; Li, Siqi

2011-07-01

388

Advances in Raman spectroscopy for explosive identification in aviation security  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

389

Multimodal fiber probe spectroscopy for tissue diagnostics applications: a combined Raman-fluorescence approach  

NASA Astrophysics Data System (ADS)

Two different optical fiber probes for combined Raman and fluorescence spectroscopic measurements were designed, developed and used for tissue diagnostics. Two visible laser diodes were used for fluorescence spectroscopy, whereas a laser diode emitting in the NIR was used for Raman spectroscopy. The two probes were based on fiber bundles with a central multimode optical fiber, used for delivering light to the tissue, and 24 surrounding optical fibers for signal collection. Both fluorescence and Raman spectra were acquired using the same detection unit, based on a cooled CCD camera, connected to a spectrograph. The two probes were successfully employed for diagnosing melanocytic lesions in a good agreement with common routine histology. The obtained results demonstrated that the multimodal approach is crucial for improving diagnostic capabilities. Further investigations were performed on colon and brain tissue samples in order to have a benchmark for diagnosing a broader range of tissue lesions and malignancies. The system presented here can improve diagnostic capabilities on a broad range of tissues and has the potential of being used for endoscopic inspections in the near future.

Cicchi, Riccardo; Anand, Suresh; Rossari, Susanna; Sturiale, Alessandro; Giordano, Flavio; De Giorgi, Vincenzo; Maio, Vincenza; Massi, Daniela; Nesi, Gabriella; Buccoliero, Anna Maria; Tonelli, Francesco; Guerrini, Renzo; Pimpinelli, Nicola; Pavone, Francesco S.

2014-03-01

390

Polarized Raman investigations of oriented animal muscle fibers affected by storage time applying a 671 nm diode laser  

NASA Astrophysics Data System (ADS)

Due to its analytical ability and sensitivity to molecular vibrations, Raman spectroscopy provides valuable information of the secondary structure of proteins. Moreover, polarized Raman spectroscopy is shown to be a useful instrument to investigate the structural changes resulting from the aging and spoilage process of meat. In this work, polarized Raman spectra were measured on oriented cuts of pork and turkey. Fresh meat slices were stored at 5 °C and measured for a consecutive time period of 10 days. A 671 nm microsystem diode laser was used as excitation light source. The laser power at the sample was 50 mW and the integration time of each Raman spectrum was set to 5 seconds. Measurements were performed with a laser beam orientation perpendicular to the long axis of the muscle fibers. In that arrangement, the fibers were aligned either parallel or perpendicular to the polarization direction of the laser source. By using the statistical method of principal components analysis (PCA), a clear separation of the meat samples can be found for fresh meat according to the orientation (parallel or perpendicular) using the first two principal components. During the storage period, this separation subsequently vanishes due to the aging process and due to an increase of the microbial spoilage of the meat surface. For the latter effect, a time-dependent distinction of the Raman spectra is presented as well. Furthermore, specific changes of conformation-sensitive Raman bands were recognized, notably a decrease of the intensities of ?-helical protein conformation.

Al Ebrahim, Halah; Sowoidnich, Kay; Schmidt, Heinar; Kronfeldt, Heinz-Detlef

2011-06-01

391

High resolution pulsed infrared cavity ringdown spectroscopy: Application to laser ablated carbon clusters  

E-print Network

light, followed by some method of blocking the laser so that the decay of radiation trappedHigh resolution pulsed infrared cavity ringdown spectroscopy: Application to laser ablated carbon ringdown spectrometer. Stimulated Raman scattering in H2 /D2 is used to downconvert the output of a SLM

Cohen, Ronald C.

392

Monitoring the oxidation of nuclear fuel cladding using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In order to observe Zircaloy-4 (Zr-4) cladding oxidation within a spent fuel canister, cladding oxidized in air at 500 °C was investigated by micro-Raman spectroscopy to measure the oxide layer thickness. Systematic Raman scans were performed to study the relationship between typical Raman spectra and various oxide layer thicknesses. The thicknesses of the oxide layers developed for various exposure times were measured by cross-sectional Scanning Electron Microscopy (SEM). The results of this work reveal that each oxide layer thickness has a corresponding typical Raman spectrum. Detailed analysis suggests that the Raman scattering peaks around wave numbers of 180 cm-1 and 630 cm-1 are the best choices for accurately determining the oxide layer thickness. After Gaussian-Lorentzian deconvolution, these two peaks can be quantitatively represented by four peaks. The intensities of the deconvoluted peaks increase consistently as the oxide layer becomes thicker and sufficiently strong signals are produced, allowing one to distinguish the bare and oxidized cladding samples, as well as samples with different oxide layer thicknesses. Hence, a process that converts sample oxide layer thickness to optical signals can be achieved.

Mi, Hongyi; Mikael, Solomon; Allen, Todd; Sridharan, Kumar; Butt, Darryl; Blanchard, James P.; Ma, Zhenqiang

2014-02-01

393

TOPICAL REVIEW: Surface-enhanced Raman scattering and biophysics  

Microsoft Academic Search

Surface-enhanced Raman scattering (SERS) is a spectroscopic technique which combines modern laser spectroscopy with the exciting optical properties of metallic nanostructures, resulting in strongly increased Raman signals when molecules are attached to nanometre-sized gold and silver structures. The effect provides the structural information content of Raman spectroscopy together with ultrasensitive detection limits, allowing Raman spectroscopy of single molecules. Since SERS

Katrin Kneipp; Harald Kneipp; Irving Itzkan; Ramachandra R. Dasari; Michael S. Feld

2002-01-01

394

Nanoparticle microinjection and Raman spectroscopy as tools for nanotoxicology studies.  

PubMed

Microinjection techniques and Raman spectroscopy have been combined to provide a new methodology to investigate the cytotoxic effects due to the interaction of nanomaterials with cells. In the present work, this novel technique has been used to investigate the effects of Ag and Fe(3)O(4) nanoparticles on Hela cells. The nanoparticles are microinjected inside the cells and these latter ones are probed by means of Raman spectroscopy after a short incubation time, in order to highlight the first and impulsive mechanisms developed by the cells to counteract the presence of the nanoparticles. The results put in evidence a different behaviour of the cells treated with nanoparticles in comparison with the control cells; these differences are supposed to be generated by an emerging oxidative stress due to the nanoparticles. The achieved results demonstrate the suitability of the proposed method as a new tool for nanotoxicity studies. PMID:21879030

Candeloro, Patrizio; Tirinato, Luca; Malara, Natalia; Fregola, Annalisa; Casals, Eudald; Puntes, Victor; Perozziello, Gerardo; Gentile, Francesco; Coluccio, Maria Laura; Das, Gobind; Liberale, Carlo; De Angelis, Francesco; Di Fabrizio, Enzo

2011-11-01

395

Carbon Raman Spectroscopy of 36 Inter-Planetary Dust Particles  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

396

Determination of butter adulteration with margarine using Raman spectroscopy.  

PubMed

In this study, adulteration of butter with margarine was analysed using Raman spectroscopy combined with chemometric methods (principal component analysis (PCA), principal component regression (PCR), partial least squares (PLS)) and artificial neural networks (ANNs). Different butter and margarine samples were mixed at various concentrations ranging from 0% to 100% w/w. PCA analysis was applied for the classification of butters, margarines and mixtures. PCR, PLS and ANN were used for the detection of adulteration ratios of butter. Models were created using a calibration data set and developed models were evaluated using a validation data set. The coefficient of determination (R(2)) values between actual and predicted values obtained for PCR, PLS and ANN for the validation data set were 0.968, 0.987 and 0.978, respectively. In conclusion, a combination of Raman spectroscopy with chemometrics and ANN methods can be applied for testing butter adulteration. PMID:23993631

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

2013-12-15

397

Continuous-wave SrMoO4 intracavity Raman laser pumped using a disk laser  

Microsoft Academic Search

The use of disk lasers to pump continuous-wave (cw) intracavity Raman lasers is discussed with a view to power scaling these devices via improved thermal management. Preliminary results for a Nd:YVO4\\/SrMoO4 Raman laser in this geometry are reported. An output power of 295 mW at the 1st Stokes wavelength of 1175 nm was obtained for 13.2 W absorbed pump power

Gerald M Bonner; Huaijin Zhang; Jiyang Wang; Alan J Kemp; Helen M Pask

2011-01-01

398

Characterization of the lithium surface by infrared and Raman spectroscopies  

Microsoft Academic Search

The chemical composition of the pristine passivation layer formed on the surface of commercial lithium foils has been investigated by polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS) and confocal Raman microspectrometry (CRM). Carbonates and hydroxides are easily detected by PM-IRRAS and on-line non-destructive analysis could be envisaged with this technique or even with the simpler IRRAS technique in dry atmosphere.

C. Naudin; J. L. Bruneel; M. Chami; B. Desbat; J. Grondin; J. C. Lassègues; L. Servant

2003-01-01

399

Doping, Strain, Orientation and Disorder of Graphene by Raman Spectroscopy  

Microsoft Academic Search

Raman spectroscopy is a fast and non-destructive method for the characterization of carbons [1]. These show two features: the G and D peaks, around 1580 and 1350cm-1 respectively. The G peak corresponds to the doubly degenerate E2g phonon at the Brillouin zone centre. The D peak is due to the breathing modes of sp^2 atoms and requires a defect for

Andrea C. Ferrari

2009-01-01

400

Structural heterogeneity of wheat arabinoxylans revealed by Raman spectroscopy  

Microsoft Academic Search

A set of arabinoxylan samples differing in their arabinose composition and various samples of arabino-xylo-oligosaccharide samples were analysed by Raman spectroscopy. Specific signatures for arabinose substitution were found in several spectral regions, that is, 400–600, 800–950 and 1030–1100cm?1. A linear relationship was observed between the peak ratio 855\\/895cm?1 of the second derivative spectra and the A\\/X ratio determined by chemical

Cécile Barron; Paul Robert; Fabienne Guillon; Luc Saulnier; Xavier Rouau

2006-01-01

401

Detection of drugs of abuse by Raman spectroscopy.  

PubMed

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

West, Matthew J; Went, Michael J

2011-09-01

402

Infrared and NIR Raman spectroscopy in medical microbiology  

NASA Astrophysics Data System (ADS)

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

Naumann, Dieter

1998-04-01

403

Medical applications of atomic force microscopy and Raman spectroscopy.  

PubMed

This paper reviews the recent research and application of atomic force microscopy (AFM) and Raman spectroscopy techniques, which are considered the multi-functional and powerful toolkits for probing the nanostructural, biomechanical and physicochemical properties of biomedical samples in medical science. We introduce briefly the basic principles of AFM and Raman spectroscopy, followed by diagnostic assessments of some selected diseases in biomedical applications using them, including mitochondria isolated from normal and ischemic hearts, hair fibers, individual cells, and human cortical bone. Finally, AFM and Raman spectroscopy applications to investigate the effects of pharmacotherapy, surgery, and medical device therapy in various medicines from cells to soft and hard tissues are discussed, including pharmacotherapy--paclitaxel on Ishikawa and HeLa cells, telmisartan on angiotensin II, mitomycin C on strabismus surgery and eye whitening surgery, and fluoride on primary teeth--and medical device therapy--collagen cross-linking treatment for the management of progressive keratoconus, radiofrequency treatment for skin rejuvenation, physical extracorporeal shockwave therapy for healing of Achilles tendinitis, orthodontic treatment, and toothbrushing time to minimize the loss of teeth after exposure to acidic drinks. PMID:24730252

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

2014-01-01

404

Simultaneous Dual-Wavelength Operation of Nd-Doped Yttrium Orthovanadate Self-Raman Laser at 1175 nm and Undoped Gadolinium Orthovanadate Raman Laser at 1174 nm  

NASA Astrophysics Data System (ADS)

A diode-pumped actively Q-switched Nd-doped yttrium orthovanadate self-Raman emission at 1175 nm and undoped gadolinium orthovanadate Raman emission at 1174 nm dual-wavelength laser is demonstrated. With the pump power of 20.5 W and pulse repetition frequency of 20 kHz, the maximum dual-wavelength output power of 1.52 W was obtained, which contained a 0.71 W 1174 nm Raman laser component and a 0.81 W 1175 nm self-Raman laser component. The corresponding dual-wavelength Raman pulse width was 14.8 ns. Experimental results indicated that the dual-wavelength Raman laser with a small wavelength separation was effectively realized through simultaneous self-Raman and Raman shift.

Shen, Hongbin; Wang, Qingpu; Zhang, Xingyu; Zhang, Lei; Zhang, Chu; Chen, Xiaohan; Cong, Zhenhua; Bai, Fen; Liu, Zhaojun

2013-04-01

405

Controlling multidimensional off-resonant-Raman and infrared vibrational spectroscopy by finite pulse band shapes  

E-print Network

Controlling multidimensional off-resonant-Raman and infrared vibrational spectroscopy by finite signals involving various combinations of temporally well-separated vibrationally resonant infrared and electronically off-resonant Raman pulses. Combinations of broadband and narrow band pulses that yield

Mukamel, Shaul

406

Coupling Raman Spectroscopy and Thermodynamic Modelling for the Estimation of pH in Fluid Inclusions  

NASA Astrophysics Data System (ADS)

Calibration procedure of carbonate-bicarbonate-carbon dioxide by Raman spectroscopy is presented and discussed with respect to the pH estimation in fluid inclusions using microthermometric data, Raman and LA-ICP-MS analysis and thermodynamic modelling.

Dubessy, J.; Martinez-Uriarte, L.; Leisen, M.; Caumon, M.-C.; Robert, P.

2014-06-01

407

Thin magnetite films on an oxidized silicon surface: Raman spectroscopy study  

NASA Astrophysics Data System (ADS)

Polycrystalline films of magnetite (Fe3O4) formed by the reactive sputtering of iron in oxygen on Si(001) substrates covered by thin (1.4 nm) or thick (1200 nm) SiO2 layers have been studied by Raman spectroscopy. It is established that (i) the ?-Fe2O3 phase is formed due to the laser-induced heating in magnetite films synthesized on thick SiO2 layers and (ii) the formation of ?-Fe2O3 phase depends on the thickness of the buffer SiO2 layer.

Vikulov, V. A.; Balashev, V. V.; Pisarenko, T. A.; Dimitriev, A. A.; Korobtsov, V. V.

2012-08-01

408

Flame studies with the coherent anti-stokes Raman spectroscopy technique  

SciTech Connect

A premixed propane-air flame has been studied by the coherent anti-stokes Raman spectroscopy technique. Single-shot thermometry has been demonstrated and the temperature uncertainty due to the broadband dye laser analyzed. A comparison with sodium-line-reversal temperatures indicates good agreement with the CARS temperatures. A retroreflecting power-reference scheme has been developed which allows simultaneous singleshot temperature and species-concentration measurements to be made in the premixed flame. An error analysis of the concentration measurements indicates that uncertainties of 5% are obtainable with the present instrumentation.

Goss, L.P.; Schreiber, P.W.; Switzer, G.L.

1983-09-01

409

Raman  

E-print Network

Abstract. Considering that crystallinity is one of the important properties that influence the end use of cellulose nanomaterials, it is important that the former be measured accurately. Recently, a new method based on near-IR FT-Raman spectroscopy was proposed to determine cellulose I crystallinity. It was reported that in the Raman spectrum of cellulose materials, the peak intensity ratio of 380 and 1,096 cm-1 bands can be used to determine cellulose crystallinity. Raman crystallinities of the calibration-set Whatman CC31 samples were correlated with the WAXS data (Segal-WAXS-21°; coefficient of determination R2 = 0.98). Average standard error calculated from replicate Raman acquisitions indicated that the Raman crystallinity model was highly reliable. In ongoing investigations, the Raman method is being applied to determine crystallinity of nanocellulose materials. Figure 1. Univariate analysis of the calibration set samples showing the correlation between calibration set crystallinity versus 380/1,096 Raman intensity ratio or WAXS crystallinity [2].

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

410

Stimulated Raman scattering imaging by continuous-wave laser excitation  

E-print Network

is demonstrated by excitation of CH stretch vibration. © 2013 Optical Society of America OCIS codes: (140 high cost and complexity of the ultrafast laser sources. Photonic crystal fibers and all-fiber laser microscopy [8]. By cw laser excitation, SRS spectroscopy of liquid benzene was shown in 1977 [9]. Recently

Cheng, Ji-Xin

411

A continuous wave SrMoO4 Raman laser.  

PubMed

We demonstrate a cw, laser diode-pumped Nd:GdVO4/SrMoO4 crystalline Raman laser. First Stokes laser output at 1173.5?nm of 2.18?W was achieved with a diode-to-first Stokes efficiency of 8.7%. With intracavity frequency doubling in LiB3O5, 3.1?W of cw yellow emission at 586.8?nm was obtained with a 12.4% diode-to-yellow efficiency. The experimental results show that SrMoO4 is an excellent stimulated Raman scattering gain material for high-power cw near-IR Stokes and yellow lasers. PMID:21326462

Yu, Haohai; Li, Zhen; Lee, Andrew J; Li, Jing; Zhang, Huaijin; Wang, Jiyang; Pask, Helen M; Piper, James A; Jiang, Minhua

2011-02-15

412

Effect of functionalization on the electrostatic charging, tunneling, and Raman spectroscopy of epitaxial graphene  

E-print Network

Effect of functionalization on the electrostatic charging, tunneling, and Raman spectroscopy functionalization and substrate dependence by Raman and scanning tunneling spectroscopies J. Appl. Phys. 111, 114306 spectroscopy J. Appl. Phys. 111, 114307 (2012); 10.1063/1.4721673 X-ray radiation effects in multilayer

413

In situ bioprocess monitoring of Escherichia coli bioreactions using Raman spectroscopy  

E-print Network

In situ bioprocess monitoring of Escherichia coli bioreactions using Raman spectroscopy Harry L detection in the 0.1 mM range. # 2003 Published by Elsevier B.V. Keywords: Raman; Spectroscopy; In situ analytes. For these reasons, vibrational spectroscopies and inference techniques to estimate

Sinskey, Anthony J.

414

Calcium oxalate in lichen biodeterioration studied using FT-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The biodeterioration of diverse natural and man-made substrata by Caloplaca aurantia, Lecanora muralis and Acarospora oxytoma has been studied using FT-Raman spectroscopy with 1064 nm laser excitation. Each of the three lichen species produce relatively large amounts of calcium oxalate in encrustations at the thallus—substratum interface during the biodeterioration process; the Raman spectroscopic technique is capable of identifying non-destructively the monohydrate, with ?(CO) stretching bands at 1463 and 1496 cm -1 and the dihydrate, with a ?(CO) stretching band at about 1475 cm(su-1). In this work, the presence of calcium oxalate monohydrate and dihydrate in the lichen encrustations is identified for these high-oxalate producing biodeteriorative lichen systems. The results indicate that the lichens adopt different methods for the production and removal of the hydrated calcium oxalates in the encrustations.

Edwards, H. G. M.; Russell, N. C.; Seaward, M. R. D.

1997-01-01

415

Monitoring of heparin concentration in serum by Raman spectroscopy within hollow core photonic crystal fiber  

NASA Astrophysics Data System (ADS)

The feasibility of using hollow core photonic crystal fiber (HC-PCF) in conjunction with Raman spectroscopy has been explored for real time monitoring of heparin concentration in serum. Heparin is an important blood anti-coagulant whose precise monitoring and controlling in patients undergoing cardiac surgery and dialysis is of utmost importance. Our method of heparin monitoring offers a novel alternative to existing clinical procedures in terms of accuracy, response time and sample volume. The optical design configuration simply involves a 785-nm laser diode whose light is coupled into HC-PCF filled with heparin-serum mixtures. By non-selectively filling HC-PCF, a strong modal field overlap is obtained. Consequently, an enhanced Raman signal (>90 times) is obtained from various heparin-serum mixtures filled HC-PCFs compared to its bulk counterpart (cuvette). The present scheme has the potential to serve as a `generic biosensing tool' for diagnosing a wide range of biological samples.

Khetani, Altaf; Tiwari, Vidhu S.; Harb, Alaa; Anis, Hanan

2011-08-01

416

Characterization of blue pigments used in automotive paints by Raman spectroscopy.  

PubMed

Micro-Raman spectroscopy was applied to forensic identification of pigments in paint chips and provided differentiation between paint samples. Sixty-six blue automotive paint samples, 26 solid and 40 metallic were examined. It was found that the majority of the collected Raman spectra provided information about the pigments present. However, in some cases, fluorescence precluded pigment identification. Using laser excitation at longer wavelengths or pretreatment to effect photobleaching often resulted in reduced fluorescence, particularly for solid color samples, and allowed pigment identification. The examined samples were compared pairwise taking into account number, location, and intensity of absorption bands in their infrared spectra. The estimated discrimination power ranged from 97% for solid paint samples to 99% for metallic paint samples. PMID:24844185

Zi?ba-Palus, Janina; Michalska, Aleksandra

2014-07-01

417

Genomic DNA characterization of pork spleen by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2013-11-01

418

Contributions of Raman spectroscopy to the understanding of bone strength.  

PubMed

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

Mandair, Gurjit S; Morris, Michael D

2015-01-01

419

[Development of Raman spectroscopy study of fluid inclusions].  

PubMed

In the present paper, the exploration process of the laser Raman analysis of fluid inclusions was reviewed and summarized. The authors tried to outlook the future research work on laser Raman analysis of fluid inclusions at low and room temperature. Research work at low temperatures: (1) Common multiple salt systems in the fluid inclusions; (2) Trying qualitative and quantitative analysis of ingredients in natural fluid inclusions; (3) Microthermometry considered first melting temperature as the eutectic temperature, and this view was suspected, so further research is needed; (4) chloride hydrate structure is inconclusive at low temperatures. Research work at room temperatures: (1) how Fe3+, Zn2+, Cu2+ and other ions being considered as the main metal ions of mineralization combine with Cl- and H2O are how to combine; (2) The reason for different concentrations of NaCl, CaCl2, MgCl2, CuCl2, ZnCl2, FeCl3 solution resulting in the shift of Raman OH stretching region (2 800-3 800 cm(-1)). PMID:25007590

Yang, Dan; Xu, Wen-Yi

2014-04-01

420

Surface-enhanced Raman spectroscopy for homeland defense  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman spectroscopy (SERS) is a spectroscopic technique that enables trace detection of analytes of relevance using fieldable equipment. SERS uses the enhanced Raman signals observed when an analyte adsorbs to a roughened metal substrate, generally gold, silver, or copper. Coupled to a microscope, single molecule detection has been demonstrated. With a fieldable instrument, enhancements of 108 compared to unenhanced Raman spectroscopy are expected, allowing trace detection in the field. Proper development of the metal substrate will optimize the sensitivity and selectivity towards the analytes of interest. In this presentation, we will discuss applications under development at EIC Laboratories that are of importance to Homeland Defense. We will review the capabilities of SERS to detect buried explosives, explosives associated with nuclear weaponry and chemicals involved in the nuclear enrichment process. We will discuss the detection of chemical and biological warfare agents in the water supply in research performed under the Joint Service Agent Water Monitor. We will demonstrate the current detection limits, the reproducibility of the signal, and results collected using actual chemical warfare agents, and show how the results can be extended to vapor detection. We will also discuss the current state-of-the art for fieldable instrumentation. The emphasis on portability and speed will be stressed; SERS acquisitions are restricted to 30 s or less.

Spencer, Kevin M.; Sylvia, James M.; Marren, Peter J.; Bertone, Jane F.; Christesen, Steven D.

2004-03-01

421

Stimulated Raman scattering of laser dye mixtures dissolved in multiple scattering media  

NASA Astrophysics Data System (ADS)

Stimulated Raman scattering (SRS) of a mixture of rhodamine 6G and pyrromethene 605 laser dyes in vesicular films is studied. It is shown that a peculiar interaction of dyes occurs under conditions of multiple scattering of light from vesicles. This interaction manifests itself as SRS excitation of one of the dyes by random lasing of the other dye, provided that the random lasing spectrum overlaps the Stokes lines of the first dye. In addition, there is energy transfer between molecules of these dyes if their luminescence and absorption spectra overlap. The results obtained confirm that the mechanism of SRS from laser dyes in multiple scattering media is similar to that in coherent-active Raman spectroscopy. These results extend the possibility of determining the vibrational spectrum of dye molecules from their secondary radiation in these media.

Yashchuk, V. P.; Komyshan, A. O.; Tikhonov, E. A.; Olkhovyk, L. A.

2014-10-01

422

A modified Raman multidimensional spectroscopic signature of blood to account for the effect of laser power.  

PubMed

Raman spectroscopy has been used for the development of a universal method for the identification of traces of all major body fluids. Multidimensional spectroscopic signatures, which account for the intrinsic sample heterogeneity and variations between donors, have been described for blood, semen, saliva, vaginal fluid and sweat. Here, we report on a shortcoming of the existing spectroscopic signature of blood due to the effect of laser power. The issue is the result of the previously discovered phenomenon of photoinduced hemoglobin aggregation. An investigation of this effect on the performance of the Raman signature is reported along with a remediating modification. This adjustment is demonstrated to extend the application of the multidimensional signatures to spectra obtained under low laser power conditions while preserving the signature's specificity. PMID:24810520

McLaughlin, Gregory; Lednev, Igor K

2014-07-01

423

Raman Laser Spectrometer Development for ExoMars  

NASA Astrophysics Data System (ADS)

The Raman Laser Spectrometer is one of the Pasteur Payload instruments, within the ESA's ExoMars mission. The aim of the work presented here is to provide a summary of the instrument design and performances. For that the instrument current characteristics and performances, and its technological ass assessment program main results are presented and discussed.

Pérez, C.; Colombo, M.; Díaz, C.; Santamaría, P.; Ingley, R.; Parrot, Y.; Maurice, S.; Popp, J.; Tarcea, N.; Edwards, H. G. M.

2013-09-01

424

An all-silicon Raman laser Haisheng Rong1  

E-print Network

.............................................................. An all-silicon Raman laser Haisheng ............................................................................................................................................................................. The possibility of light generation and/or amplification in silicon has attracted a great deal of attention1 for silicon-based opto- electronic applications owing to the potential for forming in- expensive, monolithic

Bowers, John

425

Supercontinuum generation using a continuous-wave Raman fiber laser  

Microsoft Academic Search

A supercontinuum, nearly flat spectrum covering the S, C and L transmission bands defined by the International Telecommunication Union is obtained by pumping a conventional nonzero dispersion-shifted fiber with a continuous-wave Raman fiber laser tuned to the region of small anomalous dispersion. By using a long fiber with low loss, complete power transfer from the pump to the supercontinuum is

M. González-Herráez; S. Mart??n-López; P. Corredera; M. L. Hernanz; P. R. Horche

2003-01-01

426

Application of micro-Raman and Photoluminescence spectroscopy to defect and thin film characterization  

NASA Astrophysics Data System (ADS)

Applications of micro-Raman and micro-Photoluminescence spectroscopy to defect and thin film characterization in semiconductor processing and equipment development are presented. The Raman spectrometer is coupled to a confocal laser Defect Review Tool (DRT). This system locates particles as small as 0.2 ?m, both on 200 mm and 300 mm wafers. Raman spectroscopy is fast, non-destructive, can be performed in ambient, and is capable of providing chemical state and structural (phases, stress) information down to sub-micron dimension. Its application is material specific, however, since some materials do not have Raman-active vibrations or sufficient cross-section, or have a probing depth too long (optically transparent) to be useful. In general, chemical state information is obtainable from vibrational fingerprints of covalently bonded compounds (organic, Si-H, Si-Si, etc.), some ceramics (e.g. Zr-O, Al-O etc.), and ionic species (e.g. ammonium salts). Structural information, such as residual stress (e.g. poly-Si) and phase distinction (e.g. amorphous/diamond carbon; high/low residual phases of silicide) can sometimes also be obtained. Specific examples from Applied Materials development programs are presented. These include identification and distinction of carbon particles from different hardware sources generated by NF3 clean; organic defects on Cu after CMP; identification of the compound causing Br based particles after poly-gate etch; and distinction between ceramic based aluminum particles and anodized based aluminum particles. In the area of thin film characterization we have used micro-Raman to characterize residual build-up on hardware (e.g. residue from showerhead used in the W-CVD process chamber), and the process development of coatings and film products (e.g. diamond, poly-Si).

Conti, Giuseppina; Uritsky, Yuri; Brundle, C. R.

2001-01-01

427

Accelerated Testing of HT-9 with Zirconia Coatings Containing Gallium using Raman Spectroscopy and XPS  

SciTech Connect

Laser Raman spectroscopy and x-ray photoelectron spectroscopy were used to study the evolution of composition of oxide films in the presence of zirconia coatings on miniature HT-9 alloy specimens subjected to elevated temperature in air. The experiments expanded on previous efforts to develop a quick-screening technique for candidate alloys for cladding materials (HT-9) and actinide-based mixed oxide fuel mixtures (represented by the zirconia coating) by investigating the effect of both coating composition and alloy pretreatment conditions on the high temperature reactions. In particular, the presence of the element Ga (a potential impurity in mixed oxide fuel) in the initial zirconia coating was found to accelerate the rate of oxide growth relative to that of yttria-stabilized zirconia studied previously. In addition, HT-9 samples that were subjected to different thermal pretreatments gave different results. The results suggest that the presence of Ga in a mixed oxide fuel will enhance the corrosion of HT-9 cladding under the conditions of this study, although the extent of enhancement is influenced by thermal pretreatment of the cladding material. The results also demonstrate the need to combine Raman spectroscopy with other techniques, particularly photoelectron spectroscopy, for optimizing composition and/or fabrication conditions of both cladding and oxide fuels for advanced nuclear reactors.

Windisch, Charles F.; Henager, Charles H.; Engelhard, Mark H.; Bennett, Wendy D.

2009-12-01

428

Identifying bacterial spores and anthrax hoax materials by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The distribution of Bacillus anthracis spores through the US postal system in the autumn of 2001, initiated a secondary form of terror, the mailing of hoax materials. In the past three years nearly 20,000 letters containing harmless powders have been mailed, creating additional anxiety. Thus, there is a need for analyzers that can not only identify anthrax-causing spores to save lives, but also identify hoax materials to eliminate time-consuming and costly shutdowns. Recently, we established that Raman spectroscopy has the ability to identify both Bacilli endospores and hoax materials. Here we present Raman spectra of several Bacilli spores along with the dipicolinate salts, to further define the abilities of this technology to not only identify hoax materials, but also identify spores at the genus and species level.

Farquharson, Stuart; Brouillette, Carl R.; Smith, Wayne

2004-12-01

429

Detection of nasopharyngeal carcinoma using deep NIR Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We compare depth information from below the mucosa of ex vivo tissue to diagnose nasopharyngeal carcinoma (NPC) by NIR Raman spectroscopy. Spectral diagnosis performed on a PCA-LDA model achieves a diagnostic sensitivity of 99.3% (149/150), 100% (150/150), 98% (147/150) and 96.7% (145/150), and a specificity of 96.7% (145/150), 96.7% (145/150), 96% (144/150) and 87.3% (131/150) from the surface to deeper levels using the zero separate lines, respectively. The spectra and discrimination results at different levels could reveal pathological development. Thus, the Raman spectra of deep level mucosa can be used to diagnose the stage of NPC from normal tissue.

Li, J. H.; Li, W. T.; Zhang, G. H.

2014-12-01

430

Rapid Classification of Ordinary Chondrites Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

Classification of ordinary chondrites is typically done through measurements of the composition of olivine and pyroxenes. Historically, this measurement has usually been performed via electron microprobe, oil immersion or other methods which can be costly through lost sample material during thin section preparation. Raman microscopy can perform the same measurements but considerably faster and with much less sample preparation allowing for faster classification. Raman spectroscopy can facilitate more rapid classification of large amounts of chondrites such as those retrieved from North Africa and potentially Antarctica, are present in large collections, or are submitted to a curation facility by the public. With development, this approach may provide a completely automated classification method of all chondrite types.

Fries, M.; Welzenbach, L.

2014-01-01

431

Stochastic Liouville equations for femtosecond stimulated Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Electron and vibrational dynamics of molecules are commonly studied by subjecting them to two interactions with a fast actinic pulse that prepares them in a nonstationary state and after a variable delay period T, probing them with a Raman process induced by a combination of a broadband and a narrowband pulse. This technique, known as femtosecond stimulated Raman spectroscopy (FSRS), can effectively probe time resolved vibrational resonances. We show how FSRS signals can be modeled and interpreted using the stochastic Liouville equations (SLE), originally developed for NMR lineshapes. The SLE provide a convenient simulation protocol that can describe complex dynamics caused by coupling to collective bath coordinates at much lower cost than a full dynamical simulation. The origin of the dispersive features that appear when there is no separation of timescales between vibrational variations and the dephasing time is clarified.

Agarwalla, Bijay Kumar; Ando, Hideo; Dorfman, Konstantin E.; Mukamel, Shaul

2015-01-01

432

Raman spectroscopy for DNA quantification in cell nucleus.  

PubMed

Here we demonstrate the feasibility of a novel approach to quantify DNA in cell nuclei. This approach is based on spectroscopy analysis of Raman light scattering, and avoids the problem of nonstoichiometric binding of dyes to DNA, as it directly measures the signal from DNA. Quantitative analysis of nuclear DNA contribution to Raman spectrum could be reliably performed using intensity of a phosphate mode at 1096 cm(-1) . When compared to the known DNA standards from cells of different animals, our results matched those values at error of 10%. We therefore suggest that this approach will be useful to expand the list of DNA standards, to properly adjust the duration of hydrolysis in Feulgen staining, to assay the applicability of fuchsines for DNA quantification, as well as to measure DNA content in cells with complex hydrolysis patterns, when Feulgen densitometry is inappropriate. © 2014 International Society for Advancement of Cytometry. PMID:25355529

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

2015-01-01