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1

Laser sources for Raman spectroscopy  

NASA Astrophysics Data System (ADS)

While conventional Raman Spectroscopy (RS) has predominately used fixed wavelength cw lasers, advanced Raman spectroscopic techniques such as Stimulated Raman and some types of Raman Imaging typically need pulsed lasers with sufficient energy to induce the Raman process. In addition, pulsed lasers are beneficial for the following Raman techniques: Time Resolved Raman (TRR), Resonance Raman (RR), or non linear Raman techniques, such as Coherent anti-Stokes Raman spectroscopy (CARS). Here the naturally narrower linewidth of a ns pulse width laser is advantageous to a broader linewidth ultrafast pulsed laser. In this paper, we report on the development of a compact, highly efficient, high power solid-state Ti: Sapphire laser ideally suited for many Raman spectroscopic techniques. This laser produces nanosecond pulses at kHz repetition rates with a tunable output wavelength from ~1 micron to ~200 nm and pulse energies up to 1 mJ. The narrow bandwidth of this laser (<0.1cm-1) is ideally suited for applications such as Laser-induced fluorescence (LIF) measurement of OH free-radicals concentrations, atmospheric LIDAR and Raman spectroscopy. New KBBF and RBBF deep ultraviolet (DUV) and vacuum ultraviolet (VUV) crystals are now available that enable direct doubling of the SHG output of these tunable Ti: Sapphire lasers to directly achieve wavelengths as short as 175 nm without the need to generate the 3rd harmonic and utilize frequency mixing. This results in a highly efficient output in the DUV/VUV, enabling improved signal to noise ratios (S/N) in these previously difficult wavelength regions. Photonics Industries has recently achieved a few mW of power at 193nm with such direct doubling crystals.

Kilmer, J.; Iadevaia, A.; Yin, Y.

2011-05-01

2

The utilization of diode lasers for Raman spectroscopy  

Microsoft Academic Search

The principle of operation and characteristics of diode lasers are briefly reviewed and critically compared to those of other lasers in regard to use as excitation light sources for laser Raman spectroscopy. Relative to other lasers frequently used for Raman spectroscopy, diode lasers have the advantages of smaller size, less interference from most sample fluorescence (compared to green, blue and

S. M. Angel; M. Carrabba; T. F. Cooney

1995-01-01

3

Laser tweezers Raman spectroscopy of single cells  

NASA Astrophysics Data System (ADS)

Raman scattering is an inelastic collision between the vibrating molecules inside the sample and the incident photons. During this process, energy exchange takes place between the photon and the scattering molecule. By measuring the energy change of the photon, the molecular vibration mode can be probed. The vibrational spectrum contains valuable information about the disposition of atomic nuclei and chemical bonds within a molecule, the chemical compositions and the interactions between the molecule and its surroundings. In this dissertation, laser tweezers Raman spectroscopy (LTRS) technique is applied for the analysis of biological cells and human cells at single cell level. In LTRS, an individual cell is trapped in aqueous medium with laser tweezers, and Raman scattering spectra from the trapped cell are recorded in real-time. The Raman spectra of these cells can be used to reveal the dynamical processes of cell growth, cell response to environment changes, and can be used as the finger print for the identification of a bacterial cell species. Several biophysical experiments were carried out using LTRS: (1) the dynamic germination process of individual spores of Bacillus thuringiensis was detected via Ca-DPA, a spore-specific biomarker molecule; (2) inactivation and killing of Bacillus subtilis spores by microwave irradiation and wet heat were studied at single cell level; (3) the heat shock activation process of single B. subtilis spores were analyzed, in which the reversible transition from glass-like state at low temperature to liquid-like state at high temperature in spore was revealed at the molecular level; (4) the kinetic processes of bacterial cell lysis of E. coli by lysozyme and by temperature induction of lambda phage were detected real-time; (5) the fixation and rehydration of human platelets were quantitatively evaluated and characterized with Raman spectroscopy method, which provided a rapid way to quantify the quality of freeze-dried therapeutic platelet products for long term preservation; (6) LTRS based depolarized Raman spectroscopy was developed and used to do bacterial cell identification of similar species. From these experiments, several new findings and conclusions have been obtained. (1) single spore dynamic germination was measured for the first time. The result showed the time-to-germinate of a single spore was stochastic and could be discrete. (2) the thermal nature of spore killing in solution by microwaves was identified, Spores killed directly by microwaves showed death marker in Raman spectrum; (3) The Ca-DPA inside the spore core of a spore would undergo a structure modification during heat shock, which was related to the spores' state transition from a glass-like to a rubbery-like state, this structure modification during heat shock was reversible; (4) the kinetic molecular processes of E. coli cell lysis by lysozyme and by temperature induction of bacterial phage were recorded for the first time. The different cellular processes of the lysis were revealed based on the two different mechanisms; (5) LTRS technique was successfully applied to characterize human platelet fixation; a major procedure for long term preservation of therapeutic human platelet products; (6) A depolarization laser tweezers Raman spectroscopy (DLTRS) technique was developed to enhance the ability to discriminate similar bacterial species.

Chen, De

4

Gas phase photoacoustic Raman spectroscopy using pulsed laser excitation  

NASA Astrophysics Data System (ADS)

The sensitivity of a new spectroscopic technique, photoacoustic Raman spectroscopy (PARS), has been improved substantially by the use of high-peak-power pulsed lasers. The theory for generation of photoacoustic signals from stimulated Raman scattering is outlined, and vibration-rotation Raman spectra for CO2 and CH4 are presented. Applications of PARS are discussed, and a comparison is made with other Raman techniques.

West, Gary A.; Siebert, Donald R.; Barrett, Joseph J.

1980-05-01

5

Novel developments in laser diode Raman spectroscopy  

Microsoft Academic Search

This thesis presents the last developments of a laser diode Raman spectrometer for gases, gas flows and vapors, at medium-low pressures. Results are shown for atmospheric gases under STP conditions, and also gas flows from nozzles in subsonic-sonic regimes. The system is unique in that it uses a high power laser diode passively locked by an external grating cavity in

Ricardo Javier Claps

2000-01-01

6

Tunable Laser Resonance Raman Spectroscopy of Bacteriorhodopsin  

Microsoft Academic Search

Bacteriorhodopsin is a rhodopsin-like protein found in the cell membrane of Halobacterium halobium. It shows an absorption maximum at 570 nm and, in the light, undergoes cyclic spectral changes which include a relatively long-lived complex absorbing maximally at 412 nm. Excitation profiles have been obtained with several laser frequencies for two vibrations in the resonance Raman spectrum of bacteriorhodopsin. The

Aaron Lewis; John Spoonhower; Roberto A. Bogomolni; Richard H. Lozier; Walther Stoeckenius

1974-01-01

7

Application of cheap lasers in shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has increasing importance in a wide field of applications: particularly in real time monitoring of chemical processes, testing of foodstuffs, identification of ingredients in unknown material mixtures etc. Many materials of interest have resonance wavelength close to the excitation wavelength. Resonant Raman spectroscopy can be used to advantage in these cases. The disadvantage of this technology is the presence of a strong fluorescence background in the Raman spectrum. A combination of the mechanism of resonant Raman spectroscopy with shifted excitation Raman difference spectroscopy can be used to suppress the fluorescence background. The applicability of inexpensive green lasers for this purpose and their tunability by temperature and current is investigated in this paper. The setup consists of two pigtailed lasers at a wavelength of 532 nm with a small wavelength difference switched by a fiber switch with a frequency up to 50 Hz. Every switching pulse triggers an optical spectrometer to measure the backscattered light. A resonant Raman spectrum with a minimized fluorescence background is obtained by subtraction of the two different spectra. The specific wavelengths of the two lasers were set by thermal tuning. The Raman spectra of Isopropanol and Carbon Tetrachloride have been measured in order to verify the setup.

Wolf, Stefan; Döring, Heinz

2012-05-01

8

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

9

Investigation of Laser Raman Spectroscopy for Analysis of Water Quality.  

National Technical Information Service (NTIS)

Laser Raman spectroscopy was studied as a tool for analysis of water quality. Lower limits for the detection of nitrates and sulfates in distilled water were determined to be 20 ppm and 8.5 ppm respectively. The herbicides atrazine, picloram, trifluoralin...

F. G. Ullman

1976-01-01

10

Comparative Spontaneous Raman Spectroscopy of Crystals for Raman Lasers  

Microsoft Academic Search

A comparison of the spectroscopic parameters of Raman-active vibronic modes in various crystalline materials with a view to the use of these crystals for stimulated Raman scattering (SRS) is presented. It includes data on the Raman frequency shift, linewidth, integral, and peak Raman scattering cross sections. For steady-state SRS the highest Raman gain coefficient has been proved to be in

Tasoltan T. Basiev; Alexander A. Sobol; Petr G. Zverev; Vyacheslav V. Osiko; Richard C. Powell

1999-01-01

11

Continuous tuning of silicon Raman laser for molecular spectroscopy  

Microsoft Academic Search

This work demonstrates continuous (mode-hop free) tuning of a single-mode silicon Raman laser over more than 20 GHz range which is broad enough to cover typical molecular transitions in gasses at room temperature, and allows to perform infrared absorption spectroscopy measurements of methane. Wider mode-hop free tuning could be obtained by controlling the temperature of the laser chip in sync

V. Sih; Ying-Hao Kuo; Haisheng Rong; Shengbo Xu; M. Paniccia; O. Cohen; O. Raday

2007-01-01

12

Application of laser Raman spectroscopy to dental diagnosis  

NASA Astrophysics Data System (ADS)

The aim of this research is related with the diagnosis of caries by use of a laser. We study the fundamental characterization of the diagnosis method using both fluorescence and Raman scattering spectroscopy. We try to evaluate the possibility of the caries diagnosis using Raman spectroscopy and its clinical application. We focus on the PO34- ion that flows out with the dissolution of hydroxyapatite (HAp), and the fluorescence that increases in connection with caries. The Raman line of P-O vibration is overlapped on the continuous, background spectrum by fluorescence. Consequently, we try to find out the correlation between a healthy part and a carious part by analyzing both fluorescence and Raman spectra. It was found that Raman intensity of HAp at carious lesion was weaker than those of healthy parts and the florescence intensity at the same portions was stronger. We have obtained the feasibility to estimate the degree of caries and health condition by deriving the ratio between Raman and florescence intensity. And the trial measurements in vivo were carried out to verify the availability of the method by using a fiber probe type multi channel Raman spectrometer. The process of remineralization is under researching for the development of preventive medicine.

Izawa, Takahiro; Wakaki, Moriaki

2005-03-01

13

Laser tweezers Raman spectroscopy of single cells  

Microsoft Academic Search

Raman scattering is an inelastic collision between the vibrating molecules inside the sample and the incident photons. During this process, energy exchange takes place between the photon and the scattering molecule. By measuring the energy change of the photon, the molecular vibration mode can be probed. The vibrational spectrum contains valuable information about the disposition of atomic nuclei and chemical

De Chen

2008-01-01

14

Optimizing the Laser-Pulse Configuration for Coherent Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2007-04-01

15

Optimizing the laser-pulse configuration for coherent Raman spectroscopy.  

PubMed

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

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

2007-04-13

16

In-Cavity Laser Raman Spectroscopy.  

National Technical Information Service (NTIS)

An external cavity arrangement can work with simple metal mirrors, perpendicular sample cell windows and with the laser and sample cavity on non-rigid tables separated by a large distance. The simplicity of such an external cavity may encourage other expe...

R. L. Schwiesow N. L. Abshire

1971-01-01

17

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

18

Remote cure monitoring of polymeric resins by laser Raman spectroscopy.  

National Technical Information Service (NTIS)

The validity of using Raman spectroscopy to monitor the cure chemistries of amine-cured epoxy is demonstrated by correlating NIR absorbance measurements with Raman measurements for a concentration series of bisphenol-A diglycidylether in its own reaction ...

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

1993-01-01

19

Characterization of Phyllosilicates by LIBS and Laser Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

NIR spectral signatures of phyllosilicates were recognized on Mars with wide distributions from orbit by OMEGA (on Mars Express orbiter) and CRISM (on Mars Reconnaissance Orbiter) observations. On the ground, geochemical and spectral features related to phyllosilicates were identified in rocks at two locations on Columbia Hill at Gusev crater using the data obtained by the Mars Exploration Rover (MER) Spirit. Furthermore, Opportunity rover is currently approaching the Cap of York at Endeavour crater on Meridiani Planum, where the signatures of phyllosilicates (and hydrous sulfates) were seen by CRISM. Laser-Induced Breakdown spectroscopy (LIBS) and Laser Raman spectroscopy will be used for the first time in rover missions in ChemCam on the NASA-MSL (Mars Science Laboratory) and in RLS on the ESA-ExoMars, respectively. As demonstrated by our previous studies, they are very powerful tools for characterizing the geochemistry and mineralogy aspects of the secondary minerals from aqueous alterations, especially hydrous sulfates. This study investigates the potential of LIBS and Raman spectroscopy for identifying and characterizing a variety of phyllosilicates, especially clays. Clay standards from the Clay Mineral Society were used. The LIBS measurements were made in a Planetary Environment and Analysis Chamber (PEACh) under Mars atmospheric pressure and composition, using 1064 nm as the excitation laser wavelength, same as ChemCam. The Raman measurements were made in ordinary laboratory environment using 532 nm as the excitation wavelength, same as RLS. The LIBS data were processed using custom automated software. We performed quantitative analysis of the spectra in order to evaluate the effectiveness of our method in: (a) discriminating between phyllosilicates and other silicates; (b) classifying different types of phyllosilicates (i.e., serpentine, chlorites, clays); and (c) correlating the LIBS-derived elemental abundances with the real chemical compositions of phyllosilicates. At this stage, we concentrated on investigating the LIBS peak area ratios of the Si and H emissions at 390.5 and 656.3 nm, respectively. The results from the first set study are encouraging, and we will be able to support the ChemCam investigation on MSL to classify rocks at distances. As for molecular characterization, we found that examining the Raman spectral patterns and spectral peak positions allows to: (1) classify di-octahedral and tri-octahedral phyllosilicates using the position of Si-O-Si peaks near 700 cm-1; (2) identify a variety of phyllosilicates and clays using H2O/OH peaks in 3000-4000 cm-1 and the fundamental vibration modes of polymerized SiO4 in 1150-200 cm-1; (3) characterize the Fe content in phlogopite-biotite-lepidomelane series using the relative intensities of two Raman peaks near 360 cm-1 and 550 cm-1. These results imply that laser spectroscopy (LIBS and Raman) will be powerful tools for identify, classify, and characterize phyllosilicates on Mars.

Wang, A.; Sobron, P.

2011-12-01

20

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

21

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

22

Laser Raman spectroscopy 'for in-situ' analysis of corrosion films on metals.  

National Technical Information Service (NTIS)

The principles of laser Raman spectroscopy (LRS) are discussed, with particular reference to its applications to the study of corrosion and passivation phenomena in metals in aqueous solution environments. Results of studies on corrosion inhibition by org...

C. A. Melendres

1990-01-01

23

Toward a Continuous-Wave Solid Hydrogen Raman Laser for Molecular Spectroscopy Applications  

NASA Astrophysics Data System (ADS)

We will present our recent work toward the construction of a continuous-wave solid para-H_2 Raman laser for operation first in the visible and later in the mid-infrared. Solid para-H_2 promises to be a good choice for the gain medium in a Raman laser due to its exceptionally high Raman gain coefficient. This not only presents a novel use of an interesting molecular system, but it also offers the potential for the first widely tunable laser source for high resolution spectroscopy in the 5-10 ?m range. High resolution spectroscopy requires a tunable continuous-wave laser source. However, up until now, most work in using para-H_2 as a Raman laser gain medium has taken place either with high power pulsed lasers or continuous-wave lasers which require ultra-high finesse cavities. We seek to take advantage of solid para-H_2's high Raman gain coefficient to construct a continuous-wave Raman laser with a much lower finesse cavity (F ? 150). In this presentation, we will talk about our recent work in measuring the index of refraction of solid para-H_2 in the wavelength range 430-1100 nm in preparation for building such a laser. Some details regarding the design and planning for this laser will also be discussed. Finally, current progress and anticipated work on the development of a continuous-wave solid para-H_2 Raman laser will be presented.

Evans, W. R.; Momose, T.; McCall, B. J.

2011-06-01

24

Remote cure monitoring of polymeric resins by laser Raman spectroscopy  

SciTech Connect

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

Hong, K.C.; Vess, T.M. [Lawrence Livermore National Lab., CA (United States); Lyon, R.E. [Federal Aviation Administration, Atlantic City, NJ (United States). Technical Center; Myrick, M.L. [South Carolina Univ., Columbia, SC (United States). Dept. of Chemistry

1993-05-01

25

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

Microsoft Academic Search

The use of Raman and anti-stokes Raman spectroscopy to investigate the effect of exposure to high power laser radiation on the crystalline phases of TiO2 has been investigated. Measurement of the changes, over several time integrals, in the Raman and anti-stokes Raman of TiO2 spectra with exposure to laser radiation is reported. Raman and anti-stokes Raman provide detail on both

Stephanie J. Rigby; Ala H. R. Al-Obaidi; Soo-Keun Lee; Daniel McStay; Peter K. J. Robertson

2006-01-01

26

Raman-laser spectroscopy of Wannier-Stark states  

SciTech Connect

Raman lasers are used as a spectroscopic probe of the state of atoms confined in a shallow one-dimensional (1D) vertical lattice. For sufficiently long laser pulses, resolved transitions in the bottom band of the lattice between Wannier Stark states corresponding to neighboring wells are observed. Couplings between such states are measured as a function of the lattice laser intensity and compared to theoretical predictions, from which the lattice depth can be extracted. Limits to the linewidth of these transitions are investigated. Transitions to higher bands can also be induced, as well as between transverse states for tilted Raman beams. All these features allow for a precise characterization of the trapping potential and for an efficient control of the atomic external degrees of freedom.

Tackmann, G.; Pelle, B.; Hilico, A.; Beaufils, Q.; Pereira dos Santos, F. [LNE-SYRTE, UMR 8630 CNRS, Observatoire de Paris, UPMC, 61 avenue de l'Observatoire, F-75014 Paris (France)

2011-12-15

27

Effects of laser linewidth on coherent antiStokes Raman spectroscopy  

Microsoft Academic Search

Expressions for the generated antiStokes spectral density in coherent antiStokes Raman spectroscopy (CARS) are obtained, which take into account the finite linewidths of laser sources and which may be used to analyse observed spectra. Lorentzian and gaussian laser lineshapes are taken as special cases, which enable further analytic results for single and multiline CARS spectra to be derived. Emphasis is

M. A. Yuratich

1979-01-01

28

Characterization of redeposited carbon layers on TEXTOR limiter by Laser Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Laser Raman spectroscopy is quite sensitive to detect the changes of graphite structure. In this study, the Laser Raman technique was applied to analyze the deposited carbon layers on TEXTOR test limiters of carbon (C) and tungsten (W) produced by intentional carbon deposition experiments by methane gas puffing. The carbon deposited layers showed the Raman spectra composed of two broad peaks, G-peak and D-peak, centered at around 1580 and 1355 cm-1 respectively. For W limiter, the G-peak position and the integrated intensity of the two peaks well correlate to hydrogen concentrations in the deposited carbon layers and their thicknesses, respectively. Hence Laser Raman spectroscopy is a promising tool for the in situ analysis of carbon redeposit layers on plasma facing W materials and probably on Be materials.

Egashira, K.; Tanabe, T.; Yoshida, M.; Nakazato, H.; Philipps, V.; Brezinsek, S.; Kreter, A.

2011-12-01

29

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

PubMed Central

We demonstrate a wavelength tunable optical excitation source for coherent Raman scattering (CRS) spectroscopy based on a single femtosecond fiber laser. Electrically controlled wavelength tuning of Stokes optical pulses was achieved with soliton self frequency shift in an optical fiber, and linear frequency chirping was applied to both the pump and the Stokes waves to significantly improve the spectral resolution. The coherent anti-Stokes Raman scattering (CARS) spectrum of cyclohexane 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

2011-01-01

30

Resonance Raman Spectroscopy of Metalloproteins Using CW Laser Excitation.  

PubMed

The study of metalloproteins by resonance Raman (RR) spectroscopy began two decades ago, with the publication by Long and coworkers of the first RR spectrum of the iron-sulfur protein rubredoxin (1,2). This simple spectrum, which contained only four bands attributed to the Fe-S stretching and bending vibrations of the protein FeS(4) cluster, generated much interest because of the potential of RR spectroscopy for monitoring structures of metal centers in complex biological systems (3,4). The unique ability of this technique to study the coordination environment of transition metals in proteins derives from its dramatic increase in detection sensitivrty and selectivity for vibrations closely associated with atoms at the absorbing center(s) in the molecule. When the molecule is excited with a strong monochromatic light whose energy matches that of an electric-dipole allowed electronic transition, a vibronic coupling with the electronically excited state increases the probability of observing Raman scattering from vibrational transitions in the electronic ground state, and the modes that do show enhancement are localized on the chromophore (i.e., on the group of atoms that gives rise to the electronic transition). Since vibrational frequencies are sensitive to molecular bond strength, number of atoms, geometry, and coordination environment, the positions of the enhanced Raman bands can be used to monitor the chromophoric structure. Metalloproteins frequently exhibit allowed electronic transitions, owing to ?-?* and/or ligand-metal charge-transfer (CT) transitions (5), and consequently, they give wide scope to the application of RR spectroscopy. A great many RR studies of heme proteins, cobalamin, chlorophylls, carotenoids, flavin nucleotides, the visual pigments, and bacteriorhodopsin, and a variety of iron and copper metalloprotein sites have been carried out in laboratories around the world (6-11). PMID:21400146

Czernusxewicx, R S

1993-01-01

31

Investigation of laser induced space charge fields in lithium niobate at low temperature with Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report the measurement of space charges fields generated by a laser beam at low temperatures using Raman spectroscopy. Raman spectra obtained with a focused laser exhibits frequency shifts of certain Raman peaks that appear as a function of time. Analysis of these shifts reveals that they originate from changes in the local electric field that are predominately parallel to the z-axis of the crystal. The magnitude of the frequency shifts and the corresponding maximum space charge field established inside the crystal are dependent on the defect concentration. Above a certain threshold field, the built-up space charge field is drastically reduced by discharges and builds up again afterwards. The changes in the Raman spectrum remain after the laser is turned off but disappear upon heating the sample above 200K.

Stone, Greg; Dierolf, Volkmar

2013-03-01

32

Miniaturized diode laser-based light sources for in-situ shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

Weak Raman bands are often covered by pronounced background signals due to fluorescence or Rayleigh scattering. Several techniques to separate Raman lines from the background are known. In this paper, diode laser based light sources will be presented suitable for shifted excitation Raman difference spectroscopy (SERDS). The two wavelengths are realized by varying the injection current, by addressing two micro-integrated ECLs or by temperature tuning. Due to the freedom of choice in the wavelengths using diode lasers, the emission wavelength can be selected with respect to the addressed application (e.g. the required penetration depth) or the plasmonic resonances of the substrates for surface enhanced Raman spectroscopy. Devices were developed for the wavelengths 488 nm, 671 nm, and 785 nm. The two emission wavelengths each were selected to have a spectral distance of 10 cm-1 according to the typical width of Raman lines of solid or liquid samples. Output powers between 20 mW for the shorter wavelength devices and 200 mW for the red emitting lasers were achieved at electrical power consumptions below 1 W. With a footprint of only 25 x 25 mm2 including all collimation and filter elements, these devices are well suited for portable applications. The diode lasers were implemented into Raman measurement systems. The SERDS signal-to-background ratio was improved by several orders of magnitude.

Sumpf, Bernd; Maiwald, Martin; Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

2013-05-01

33

Investigation of Notchless In situ ?-Raman Spectroscopy  

Microsoft Academic Search

Micro-Raman spectroscopy is a powerful method for analyzing the bond structure of matter. The Laser Materials Processing group uses a femtosecond pulsed laser to create waveguides in Chalcogenide and Oxide glasses. Raman spectroscopy is used to identify changes in the glasses before and after laser irradiation. More effective is in situ Raman spectroscopy, tracking the changes in the glass in

Jordan Cox

34

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

Microsoft Academic Search

ABSTRACT 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 systemwas 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

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

35

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

Microsoft Academic Search

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

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

2006-01-01

36

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

Microsoft Academic Search

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

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

2006-01-01

37

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

Microsoft Academic Search

The extreme Venus surface temperatures (~740 K) and atmospheric pressures (~93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical

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

2010-01-01

38

Laser micro-Raman spectroscopy of single-point diamond machined silicon substrates  

Microsoft Academic Search

Laser micro-Raman spectroscopy was used to examine the silicon substrates machined by single-point diamond turning at machining scales ranging from 10 to 1000 nm under plane strain conditions. The results showed that the subsurface layer was partially transformed to amorphous, the extent of amorphization depending strongly on the undeformed chip thickness. The intensities of the crystalline phase and the amorphous

Jiwang Yan

2004-01-01

39

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

SciTech Connect

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

Henley, S.J.; Carey, J.D.; Silva, S.R.P. [Nano-Electronics Centre, Advanced Technology Institute, School of Electronics and Physical Sciences, University of Surrey, Guildford GU2 7XH (United Kingdom)

2006-02-20

40

Laser Diode Raman Spectroscopy Without the Rayleigh Line  

Microsoft Academic Search

The intensity of Rayleigh scattering which is typically four to ten orders of magnitude larger than rotational Raman scattering sets severe limitations on the measurements of Raman intensities close to the excitation line. In order to remove this unwanted light, it is common to use either a subtractive filter stage double spectrometer or a holographic filter. These solutions carry a

Jamshid Sabbaghzadeh

1995-01-01

41

Characterisation of diamond coatings with different morphologies by Raman spectroscopy using various laser wavelengths.  

PubMed

Since the beginning of low-pressure diamond synthesis, Raman spectroscopy has been widely used to identify and characterise the quality of diamonds. The diamond crystal is characterised by a Raman peak at about 1,332 cm(-1). Other peaks are associated with miscellaneous carbon structures, e.g. graphite and amorphous phases. In recent years, both well-faceted crystalline diamonds and nanocrystalline and ultrananocrystalline diamonds have been investigated. For these fine-grained materials, the diamond peak at 1,332 cm(-1) disappears and the intensities of peaks at other wavelengths increase. To study the influence of the Raman laser wavelength, three lasers were used (472.681 nm, blue; 532.1 nm, green; 632.81 nm, red). For well-faceted diamonds, the Raman spectra with blue and green laser light were similar. A shift of the peak maxima and different intensities were observed. With use of the red laser, a strong luminescence peak and low peak intensities for the various carbon-related peaks occurred. When the diamond morphology changes from well-faceted to fine-grained ballas diamond, the spectra are similar for all three lasers. PMID:22362277

Rudigier, Moritz; Haubner, Roland

2012-02-24

42

Effects of laser field statistics on coherent anti-Stokes Raman spectroscopy intensities  

Microsoft Academic Search

The effects of intensity fluctuations in the frequency-doubled output of a multimode Nd:YAG pump laser on coherent anti-Stokes Raman spectroscopy (CARS) signal generation have been investigated in a crossed-beam, two-color CARS experiment. Measurements of signal intensity as a function of time delay in one pump beam show a maximum at zero delay. In measurements on a single unresolved transition, the

L. A. Rahn; R. L. Farrow; R. P. Lucht

1984-01-01

43

Analysis of RBC damage using laser tweezers Raman spectroscopy (LTRS) during femtosecond laser optical trapping  

NASA Astrophysics Data System (ADS)

We monitored cell viability and damage under femtosecond laser irradiation using aser weezers Raman pectroscopy (LTRS) which is becoming a powerful tool for the analysis of biological materials. Femtosecond lasers are more frequently used as a light source for optical tweezers since they enable nonlinear optical phenomena such as two-photon absorption or second harmonic generation trapping. Femtosecond laser optical trapping similar to thee CW laser optical trapping except that optical damage can be easily induced due to extremely high peak power of femtosecond pulses. We monitored the Raman signal changes as a marker for optical damage. We used red blood cell (RBC) as a target sample and first used the CW laser beams to trap the RBC from the bottom of the chamber. After the trapped RBC is moved to a desired depth, we switched the laser mode to mode-locked mode and monitored the Raman signals as a function of the laser irradiation time. It was observed that the Raman shift at 1543 cm-1 may be a good marker for optical damage both for CW and femtosecond laser trapping.

Ju, Sung-bin; Pyo, Jin-woo; Jang, Jae-young; Lee, Seungduk; Kim, Beop-Min

2008-03-01

44

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

NASA Astrophysics Data System (ADS)

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

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

1998-05-01

45

Raman spectroscopy study of laser-shocked TATB-based explosives  

NASA Astrophysics Data System (ADS)

We have developed a single-pulse Raman spectroscopy experiment dedicated to the study of laser-shocked explosives. The shocks were generated using the laser-driven flyer technique. The nanosecond pulse of a Nd:YAG laser (? = 1064 nm) was focused on a BK7 substrate coated with an ablation and an aluminium (Al) layer. The Al layer was used as the flyer. Our set-up can provide flyer velocities in the range 1500 to 3000 m/s with 15 ?m thick Al foils which yields to maximum peak pressure of about 20 GPa on TATB samples. Single-shot Raman spectroscopy of shocked samples was performed using the second harmonic of a nanosecond Nd:YAG laser (? = 532 nm) focused on the back side of the samples through a glass window. In order to estimate the pressure of the probed sample, measurements of the particle velocity at the explosive-window interface were performed at the same time using the Photon Doppler Velocimetry system developed at CEA. Hydrodynamic simulations were also carried out. The first results obtained with this set-up on pressed samples of TATB based explosives are presented in this paper.

Hebert, Philippe; Bouyer, Viviane; Rideau, Joel; Doucet, Michel; Terzulli, Louis-Pierre

2011-06-01

46

Imaging with Raman spectroscopy.  

PubMed

Raman spectroscopy, based on the inelastic scattering of a photon, has been widely used as an analytical tool in many research fields. Recently, Raman spectroscopy has also been explored for biomedical applications (e.g. cancer diagnosis) because it can provide detailed information on the chemical composition of cells and tissues. For imaging applications, several variations of Raman spectroscopy have been developed to enhance its sensitivity. This review article will provide a brief summary of Raman spectroscopy-based imaging, which includes the use of coherent anti-Stokes Raman spectroscopy (CARS, primarily used for imaging the C-H bond in lipids), surface-enhanced Raman spectroscopy (SERS, for which a variety of nanoparticles can be used as contrast agents), and single-walled carbon nanotubes (SWNTs, with its intrinsic Raman signal). The superb multiplexing capability of SERS-based Raman imaging can be extremely powerful in future research where different agents can be attached to different Raman tags to enable the interrogation of multiple biological events simultaneously in living subjects. The primary limitations of Raman imaging in humans are those also faced by other optical techniques, in particular limited tissue penetration. Over the last several years, Raman spectroscopy imaging has advanced significantly and many critical proof-of-principle experiments have been successfully carried out. It is expected that imaging with Raman Spectroscopy will continue to be a dynamic research field over the next decade. PMID:20497112

Zhang, Yin; Hong, Hao; Cai, Weibo

2010-09-01

47

Laser micro-Raman spectroscopy of single-point diamond machined silicon substrates  

NASA Astrophysics Data System (ADS)

Laser micro-Raman spectroscopy was used to examine the silicon substrates machined by single-point diamond turning at machining scales ranging from 10 to 1000 nm under plane strain conditions. The results showed that the subsurface layer was partially transformed to amorphous, the extent of amorphization depending strongly on the undeformed chip thickness. The intensities of the crystalline phase and the amorphous phase show opposite tendencies with respect to the undeformed chip thickness. In brittle regime machining, Raman spectra differ depending on the test locations. The intensity of the amorphous phase reaches maximum near the ductile-brittle transition boundary. In ductile regime machining, the intensity of the amorphous phase decreased sharply as the undeformed chip thickness decreased. This work provides technological insights into the possibility of direct manufacturing of subsurface damage-free optical and optoelectronic products of silicon by ductile machining without the need for or with a decreased need for subsequent etching or chemomechanical polishing.

Yan, Jiwang

2004-02-01

48

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

49

Nanoparticle detection in aqueous solutions using Raman and Laser Induced Breakdown Spectroscopy  

NASA Astrophysics Data System (ADS)

We show the chemical identification and quantification of the concentration and size of nanoparticle (NP) dispersions in aqueous solutions by using a combination of Raman Spectroscopy and Laser Induced Breakdown Spectroscopy (LIBS). The two spectroscopic techniques are applied to demonstrate the NP detection for off-line configuration. The implementation of the techniques for further in-line and on-line NP monitoring will allow for the optimization of the synthesis process, reduction of the failure rate and improvement of NP quality. We demonstrate the implementation of the Raman-LIBS technique on two metaloxide nanoparticles: titanium dioxide (TiO2) and a rare earth sesquioxide nanoparticle, holmium oxide (Ho2O3). The determination of the elemental (LIBS) and molecular (Raman) compositions, as well as the determination of the particle size down to 5 nm is demonstrated. The LIBS spectra of NP dispersions reveal the absorption of the continuum emission by the electrons present in the plasma via the inverse Bremsstrahlung effect. This effect manifests as the appearance of dips in the LIBS spectrum, rather than the conventional emission peaks. An interpretation of these spectra that incorporates this absorption effect is presented, enabling new opportunities for understanding the LIBS spectra of liquids.

Sovago, Maria; Buis, Ernst-Jan; Sandtke, Marijn

2013-09-01

50

Monitoring trehalose uptake and conversion by single bacteria using laser tweezers Raman spectroscopy.  

PubMed

Having the ability to monitor metabolic activity at the scale of single bacterial cells noninvasively would enable us to follow changes in the distribution of activity in bacterial systems which is of major importance for topics such as integration of metabolism and development, metabolic engineering, microbial activity and drug resistance, cell-cell interactions, and quorum sensing. Here, we used laser tweezers Raman spectroscopy to monitor the in vivo real-time uptake and conversion of trehalose by single bacterial cells. This approach can be used for the quantitative determination of sugar uptake by a single bacterium and its metabolic response to the sugar application with time. We show that uptake of trehalose can be quantified in single living bacterial cells held in place by an optical trap while simultaneously collecting Raman spectra upon application of sugar to the medium. This technique yields real-time chemical information in a label-free manner, thus eliminating the limitations of toxicity of the isotopic probes common in studying transport processes. It can substitute the laborious and time-consuming analytical evaluation. Although the single-cell Raman spectroscopy method demonstrated here is focused on the study of trehalose uptake by Sinorhizobium meliloti, the demonstrated approach is applicable to many different organisms and carbohydrates in general. PMID:23796054

Avetisyan, Anna; Jensen, John Beck; Huser, Thomas

2013-07-10

51

Detection and characterization of explosives using Raman spectroscopy: identification, laser heating, and impact sensitivity  

Microsoft Academic Search

Raman spectroscopy has been shown to be a useful tool for characterizing neat crystalline explosive samples and for identifying principle components in many propellant and explosive formulations. Recently, we have been investigating changes in Raman spectra of explosives and propellant formulations which occur as the temperature approaches the melting point of the sample. We report recent measurements of Raman spectra

Kevin L. McNesby; Nicholas F. Fell; John A. Vanderhoff

1997-01-01

52

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.

2012-05-01

53

Spontaneous Raman spectroscopy of tungstate and molybdate crystals for Raman lasers  

Microsoft Academic Search

Spontaneous Raman spectra of tungstate (MeWO4) and molybdate (MeMoO4) crystals with sheelite structure were investigated (Me=Ca, Sr, Ba, Pb). The energy shift and line broadening of internal vibrational modes were measured in the temperature range from 77 K to the melting point by means of a high temperature Raman spectroscopic technique. The phase transition from sheelite to cubic structure was

T. T Basiev; A. A Sobol; Yu. K Voronko; P. G Zverev

2000-01-01

54

Intracavity Raman lasers  

SciTech Connect

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

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

1989-02-01

55

Laser-excited luminescence of trace Nd3+ impurity in LaBr3 revealed by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Unexpected additional bands with obvious non-vibrational features were observed in Raman spectra of LaBr3. Extensive study was carried out to reveal the origin of these bands. Results indicate that the additional bands correspond to laser-excited luminescence of trace Nd3+ impurity unintentionally introduced from the La2O3 raw material, which was further confirmed by Raman spectra of specially prepared Nd3+-doped LaBr3 and LaOBr samples. The luminescence properties of Nd3+ in different matrix were compared and discussed. The ultrasensitivity of Raman spectroscopy in detecting trace luminescent lanthanide ions shows good potential for analytical applications.

Yu, Jinqiu; Cui, Lei; He, Huaqiang; Hu, Yunsheng; Wu, Hao; Zeng, Jia; Liu, Yuzhu

2012-10-01

56

In situ high P-T Raman spectroscopy and laser heating of carbon dioxide.  

PubMed

In situ high P-T Raman spectra of solid CO(2) up to 67 GPa and 1,660 K have been measured, using a micro-optical spectroscopy system coupled with a Nd:YLF laser heating system in diamond anvil cells. A metallic foil was employed to efficiently absorb the incoming Nd:YLF laser and heat the sample. The average sample temperature was accurately determined by detailed balance from the anti-Stokes/Stokes ratio, and was compared to the temperature of the absorber determined by fitting the thermal radiation spectrum to the Planck radiation law. The transformation temperature threshold and the transformation dynamics from the molecular phases III and II to the polymeric phase V, previously investigated only by means of temperature quench experiments, was determined at different pressures. The P-T range of the transformation, between 640 and 1,100 K in the 33-65 GPa pressure interval, was assessed to be a kinetic barrier rather than a phase boundary. These findings lead to a new interpretation of the high P-T phase diagram of carbon dioxide. Furthermore, our approach opens a new way to perform quantitative in situ Raman measurements under extremely high pressures and temperatures, providing unique information about phase relations and structural and thermodynamic properties of materials under these conditions. PMID:15281882

Santoro, Mario; Lin, Jung-fu; Mao, Ho-kwang; Hemley, Russell J

2004-08-01

57

Monitoring and rapid quantification of total carotenoids in Rhodotorula glutinis cells using laser tweezers Raman spectroscopy.  

PubMed

Rhodotorula glutinis is known to accumulate large amounts of carotenoids under certain culture conditions, which have very important industrial applications. So far, the molecular mechanism of regulating carotenogenesis is still not well understood. To better understand the carotenogenesis process, it requires methods that can detect carotenogenesis rapidly and reliably in single live cells. In this paper, a method based on laser tweezers Raman spectroscopy (LTRS) was developed to directly detect carotenoids, as well as other important biological molecules in single live R. glutinis cells. The data showed that the accumulation of carotenoids and lipids occurred mainly in the late exponential and stationary phases when the cell growth was inhibited by nutrient limitation. Meanwhile, the carotenoid concentration changed together with the concentration of nucleic acids, which increased in the first phase and decreased in the last phase of the culture. These data demonstrate that LTRS is a rapid, convenient, and reliable method to study the carotenogenesis process in vivo. PMID:21054502

Tao, Zhanhua; Wang, Guiwen; Xu, Xiaodong; Yuan, Yufeng; Wang, Xue; Li, Yongqing

2010-11-08

58

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

NASA Astrophysics Data System (ADS)

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

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

2012-09-01

59

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

60

XPS (x-ray photoelectron spectroscopy), AES (Auger electron spectroscopy), RBS (Rutherford backscattering spectroscopy), NRA (nuclear reaction analysis) and laser Raman studies of high temperature corrosion  

SciTech Connect

This paper describes the basic principles of five surface and near surface analysis methods and explores ways they can be used to gather information relevant to oxidation and high temperature corrosion. The techniques discussed include: Auger electron spectroscopy, x-ray photoelectron spectroscopy, Rutherford backscattering spectroscopy, nuclear reaction analysis and laser Raman spectroscopy. Advantages and limitations of each method are highlighted. To illustrate the types of information available, four of the techniques have been used to examine the oxide formed on a nickel-chromium-thoria alloy. Other examples, original and from the literature, are used to demonstrate special characteristics of the techniques. Particular attention is devoted to the possibilities and limitations of high temperature studies in ultra high vacuum analytical systems.

Baer, D.R.; Dake, L.S.

1987-01-01

61

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

NASA Astrophysics Data System (ADS)

The extreme Venus surface temperatures (~740 K) and atmospheric pressures (~93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical science goals without the risks associated with collecting samples and bringing them into the lander. Wiens et al. [1] and Sharma et al. [2] demonstrated that both analytical techniques can be integrated into a single instrument capable of planetary missions. The focus of this paper is to explore the capability to probe geologic samples with Raman - LIBS and demonstrate quantitative analysis under Venus surface conditions. Raman and LIBS are highly complementary analytical techniques capable of detecting both the mineralogical and geochemical composition of Venus surface materials. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from Soviet Venera and VEGA landers that collectively suggest a surface composition that is primarily tholeiitic basaltic [3] with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. These landers were not equipped to probe the surface mineralogy as can be accomplished with Raman spectroscopy. Based on the observed compositional differences and recognizing the imprecise nature of the existing data, 15 samples were chosen to constitute a Venus-analog suite for this study, including five basalts, two each of andesites, dacites, and sulfates, and single samples of a foidite, trachy-andesite, rhyolite, and basaltic trachyandesite under Venus conditions. LIBS data reduction involved generating a partial least squares (PLS) model with a subset of the rock powder standards to quantitatively determine the major elemental abundance of the remaining samples [4]. PLS analysis suggests that the major element compositions can be determined with root mean square errors ca. 5% (absolute) for SiO2, Al2O3, Fe2O3(total), MgO, and CaO, and ca. 2% or less for TiO2, Cr2O3, MnO, K2O, and Na2O. Finally, the Raman experiments have been conducted under supercritical CO2 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. [1] Wiens R.C., et al. (2005) Spect. Acta A 61, 2324; [2] Sharma, S. K. et al. (2007) Spect. Acta A, 68 , 1036 (2007); [3] Barsukov VL (1992) Venusian Igneous Rocks. In Venus Geology, Geochemistry, and Geophysics (eds. VL Barsukov et al.). Univ. Arizona Press, pp. 165-176. [4] Tucker, J.M. et al. (2010) Chem. Geol., in press.

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

2010-12-01

62

Evaluation of poly-Si thin film crystallized by solid green laser annealing using UV\\/visible Raman spectroscopy  

Microsoft Academic Search

Depth and in-plane distributions of the crystal qualities in low-temperature polycrystalline Si (LTPS) films fabricated by\\u000a green laser annealing with s and p-polarizations and commercial excimer laser annealing were evaluated by Raman spectroscopy\\u000a with UV and visible excitation laser sources from the front and back surfaces. A quasi-line excitation source provides a one-dimensional\\u000a profile with 200-nm spatial resolution and step-by-step

Atsushi Ogura; Yasuto Kakemura; Daisuke Kosemura; Tetsuya Yoshida; Miyuki Masaki; Kenichirou Nishida; Ryusuke Kawakami; Naoya Yamamoto

2008-01-01

63

Laser Raman spectroscopy. (Latest citations from the INSPEC: Information Services for the Physics and Engineering Communities database). Published Search  

SciTech Connect

The bibliography contains citations concerning research and development of laser Raman spectroscopy for the study of organic and inorganic materials in solid states, liquid phases, or gaseous phases. Topics include gas adsorption on metal surfaces, studies of electrolytes and catalysts, characterization of semiconductor materials and surfaces, combustion analysis, structural studies of polymers, nuclear waste analysis, and probing picosecond processes. Raman spectroscopic applications in clinical diagnosis, studies of tumor cells and viruses, nucleic acid research, and structural analysis of proteins are presented. (Contains a minimum of 237 citations and includes a subject term index and title list.)

Not Available

1992-12-01

64

Laser heating effects in the characterization of carbon fibers by Raman spectroscopy  

Microsoft Academic Search

The first-order Raman spectra of individual 8-?m-diam PAN-derived carbon fibers which had been annealed at five temperatures from 1700 to 2800 °C are measured as a function of incident laser power from 1 to 140 mW. In all fibers studied, the Raman frequencies of the graphite G band at ca. 1580 cm?1 and the disordered-induced D band at ca. 1360

Joel W. Ager; D. Kirk Veirs; Jacob Shamir; Gerd M. Rosenblatt

1990-01-01

65

Laser heating effects in the characterization of carbon fibers by Raman spectroscopy  

Microsoft Academic Search

The first-order Raman spectra of individual 8-μm-diam PAN-derived carbon fibers which had been annealed at five temperatures from 1700 to 2800 °C are measured as a function of incident laser power from 1 to 140 mW. In all fibers studied, the Raman frequencies of the graphite {ital G} band at ca. 1580 cm⁻¹ and the disordered-induced {ital D} band at

Joel W. Ager III; D. Kirk Veirs; Jacob Shamir; Gerd M. Rosenblatt

1990-01-01

66

Resonance Raman spectroscopy of red blood cells using near-infrared laser excitation  

Microsoft Academic Search

Resonance Raman spectra of oxygenated and deoxygenated functional erythrocytes recorded using 785 nm laser excitation are\\u000a presented. The high-quality spectra show a mixture of enhanced A1g, A2g, B1g, B2g, Eu and vinyl modes. The high sensitivity of the Raman system enabled spectra from four oxygenation and deoxygenation cycles\\u000a to be recorded with only 18 mW of power at the sample over a

Bayden R. Wood; Peter Caspers; Gerwin J. Puppels; Shveta Pandiancherri; Don McNaughton

2007-01-01

67

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

NASA Astrophysics Data System (ADS)

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 (~1.4 MW/cm2) 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.; Veríssimo, C.; Moshkalev, S. A.

2013-07-01

68

Novel single-cell functional analysis of red blood cells using laser tweezers Raman spectroscopy: application for sickle cell disease.  

PubMed

Laser tweezers Raman spectroscopy was used to characterize the oxygenation response of single normal adult, sickle, and cord blood red blood cells (RBCs) to an applied mechanical force. Individual cells were subjected to different forces by varying the laser power of a single-beam optical trap, and the intensities of several oxygenation-specific Raman spectral peaks were monitored to determine the oxygenation state of the cells. For all three cell types, an increase in laser power (or mechanical force) induced a greater deoxygenation of the cell. However, sickle RBCs deoxygenated more readily than normal RBCs when subjected to the same optical forces. Conversely, cord blood RBCs were able to maintain their oxygenation better than normal RBCs. These results suggest that differences in the chemical or mechanical properties of fetal, normal, and sickle cells affect the degree to which applied mechanical forces can deoxygenate the cell. Populations of normal, sickle, and cord RBCs were identified and discriminated based on this mechanochemical phenomenon. This study demonstrates the potential application of laser tweezers Raman spectroscopy as a single-cell, label-free analytical tool to characterize the functional (e.g., mechanical deformability, oxygen binding) properties of normal and diseased RBCs. PMID:23537725

Liu, Rui; Mao, Ziliang; Matthews, Dennis L; Li, Chin-Shang; Chan, James W; Satake, Noriko

2013-03-26

69

Aspirin-DNA interaction studied by FTIR and laser Raman difference spectroscopy.  

PubMed

The interaction of calf-thymus DNA with aspirin is investigated in aqueous solution at pH 7-6 with drug/DNA (phosphate) molar ratios of r = 1/40, 1/20, 1/10, 1/5, 1/2, 1 and 2. Fourier transform infrared (FTIR) and laser Raman difference spectroscopy are used to determine drug binding sites, sequence preference and DNA secondary structure, as well as the structural variations of aspirin-DNA complexes in aqueous solution. Spectroscopic evidence showed that at low aspirin concentration (r =1/40), drug-DNA interaction is mainly through the backbone PO2 groups and the A-T base pairs. Such interaction largely perturbs the phosphate vibration at 1222 cm(-1) and the A-T bands at 1663 and 1609 cm(-1) with no major helix destabilization. At higher drug concentration (r > 1/20), the participation of the G-C bases in drug-DNA complexation was evident by strong perturbations of the guanine and cytosine vibrations at 1717 and 1494 cm(-1), with a partial helix destabilization. A major alteration of the B-DNA structure towards A-DNA occurs on drug complexation. The aspirin interaction was through anion CO and COOCH3 donor atoms with those of the backbone PO2 group and DNA bases donor sites (directly or indirectly via H2O molecules). PMID:8612758

Neault, J F; Naoui, M; Manfait, M; Tajmir-Riahi, H A

1996-03-11

70

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.

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

2009-01-01

71

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

PubMed Central

The ?-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 mono-exponential decays, with time-constants of ~120 ns, independent of the final T (Tf =18 to 61°C), provided the initial T (Ti) was held constant (60C). 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° 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.

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

2010-01-01

72

Raman Fiber Lasers  

NASA Astrophysics Data System (ADS)

The use of stimulated Raman scattering (SRS) as a means of amplifying signals in telecommunication systems has been demonstrated since 1976 [1]. Yet despite its advantages over erbium-doped fiber, Raman amplification was not used in the first generation of deployed optically amplified systems. One of the principal reasons for this was the lack of reliable high-power pump sources needed for Raman amplification. It was in this environment that the cascaded Raman fiber laser (RFL) was invented.

Headley, C.; Mermelstein, M.; Bouteiller, J.-C.

73

Stand-off UV Laser Induced Fluorescence and UV Enhanced Raman Spectroscopy for Mineral Analysis  

Microsoft Academic Search

INO has developed a stand-off Laser Induced Fluorescence and Raman sensor and has measured mineral spectra from a distance of 10 meters. Identification is possible using a 355 nm excitation and analyzing the returned signal in the 390 to 640 nm range.

F. Babin; N. Hô; P.-F. Paradis; S. Deblois; F. Châteauneuf

2011-01-01

74

Stand-off UV Laser Induced Fluorescence and UV Enhanced Raman Spectroscopy for Mineral Analysis  

NASA Astrophysics Data System (ADS)

INO has developed a stand-off Laser Induced Fluorescence and Raman sensor and has measured mineral spectra from a distance of 10 meters. Identification is possible using a 355 nm excitation and analyzing the returned signal in the 390 to 640 nm range.

Babin, F.; Hô, N.; Paradis, P.-F.; Deblois, S.; Châteauneuf, F.

2011-03-01

75

Surface Enhanced Raman Spectroscopy Surface Enhanced Raman Spectroscopy Surface Enhanced Raman Spectroscopy Surface Enhanced Raman Spectroscopy  

Microsoft Academic Search

Recently, Surface enhanced Raman Spectroscopy (SERS) has been rediscovered as a powerful experimental technique. In this report, I will discuss the development and theory of SERS. I will discuss its discovery and early theoretical models and present a simplified conceptual model which illustrates the key features of SERS. A general experimental method will be presented in the context of modern

Scott Parker

76

A novel concept for in situ gas-phase laser Raman spectroscopy for solid oxide fuel cell research  

NASA Astrophysics Data System (ADS)

A planar solid oxide fuel cell (SOFC) operated with hydrogen at T = 1,123 K was equipped with an optically transparent anode flow field to apply species concentration measurements by 1D laser Raman scattering. The flow channels had a cross section of 3 mm × 4 mm and a length of 40 mm. The beam from a pulsed high-power frequency-doubled Nd:YAG laser ( ? = 532 nm) was directed through one channel and the Raman-scattered light from different molecular species was imaged onto an intensified CCD camera. The main goal of the study was an assessment of the potential of this experimental configuration for a quantitative determination of local gas concentrations. The paper describes the configuration of the optically accessible SOFC, the laser system and optical setup for 1D Raman spectroscopy as well as the challenges associated with the measurements. Important aspects like laser pulse shaping, signal background and signal quality are addressed. Examples of measured species concentration profiles are presented.

Schiller, G.; Auer, C.; Bessler, W. G.; Christenn, C.; Ilhan, Z.; Szabo, P.; Ax, H.; Kapadia, B.; Meier, W.

2013-04-01

77

Raman spectroscopy of piezoelectrics  

NASA Astrophysics Data System (ADS)

Raman spectroscopy represents an insightful characterization tool in electronics, which comprehensively suits the technological needs for locally and quantitatively assessing crystal structures, domain textures, crystallographic misalignments, and residual stresses in piezoelectric materials and related devices. Recent improvements in data processing and instrumental screening of large sampling areas have provided Raman spectroscopic evaluations with rejuvenating effectiveness and presently give spin to increasingly wider and more sophisticated experimental explorations. However, the physics underlying the Raman effect represents an issue of deep complexity and its applicative development to non-cubic crystallographic structures can yet be considered in its infancy. This review paper revisits some applicative aspects of the physics governing Raman emission from crystalline matter, exploring the possibility of disentangling the convoluted dependences of the Raman spectrum on crystal orientation and mechanical stress. Attention is paid to the technologically important class of piezoelectric materials, for which working algorithms are explicitly worked out in order to quantitatively extract both structural and mechanical information from polarized Raman spectra. Systematic characterizations of piezoelectric materials and devices are successively presented as applications of the developed equations. The Raman response of complex crystal structures, described here according to a unified formalism, is interpreted as a means for assessing both crystallographic textures and stress-related issues in the three-dimensional space (thus preserving their vectorial and tensorial nature, respectively). Statistical descriptions of domain textures based on orientation distribution functions are also developed in order to provide a link between intrinsic single-crystal data and data collected on polycrystalline (partly textured) structures. This paper aims at providing rigorous spectroscopic foundations to Raman approaches dealing with the analyses of functional behavior and structural reliability of piezoelectric devices.

Pezzotti, Giuseppe

2013-06-01

78

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

NASA Astrophysics Data System (ADS)

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

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

2012-05-01

79

Effect of pump-laser linewidth on noise in single-pulse coherent anti-Stokes Raman spectroscopy temperature measurements.  

PubMed

When N(2) is used as the probe molecule in a stable premixed propane-air flame near 2100 K, the standard deviation in single-pulse coherent anti-Stokes Raman spectroscopy (CARS) temperature measurements is shown to decrease by 20% as the pump-laser linewidth increases from

Barton, S A; Garneau, J M

1987-07-01

80

Discrimination of Microorganisms and Determination of 13C Uptake Using Confocal Laser Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

The ability to discriminate members of microbial community and to measure the resource allocation relationships at the micron scale has been a long-term goal of microbiologists. Thanks to recent advancements in integrated microscopic and spectroscopic platforms it is now possible to measure spatial heterogeneity in a microbial community using Raman spectroscopic mapping. We have used confocal Raman spectroscopy both to discriminate microorganisms based on the spectral signatures and the uptake isotopically labeled substrates based on spectral shifts. Initially Raman measurements were made both on dried mounts and on live cultures of four isolates. The Raman signatures of isolates were used as training data to develop a methodology to discriminate between isolates and validate against isolate unknowns. Similarly, we were able to measure microbial uptake of 13C labeled glucose. We relied on the isotopic shift of phenylalanine and other prominent spectral features to calibrate the uptake of 13C. These initial data were used to measure community composition and 13C uptake in mixed cultures.

Hess, N. J.; Webb-Robertson, B. M.; Fansler, S.; Bailey, V. L.

2011-12-01

81

Laser Raman gas thermometry  

Microsoft Academic Search

A laser Raman thermometric technique is described which permits remote temperature sensing in combustor environments by monitoring N2 vibrational Raman scattering induced by a pulsed dye laser. Temperature is inferred from the ratio of the vibrational anti-Stokes and Stokes scattering signatures. Due to the large energy exchange which accompanies vibrational scattering, the scattered intensities are well-displaced spectrally from the exciting

A. C. Eckbreth

1974-01-01

82

Fluorescence rejection by shifted excitation Raman difference spectroscopy  

Microsoft Academic Search

Raman spectroscopy is often hampered by strong fluorescence background that can easily bury the much weaker Raman signal. One of the most widely used techniques to reject the fluorescence disturbance is the shifted-excitation Raman difference spectroscopy (SERDS), which incorporates multiple wavelengths as excitation sources. This paper proposed a SERDS system with 532 nm and 526.5 nm DPSS lasers and a

Wenlong Zou; Zhijian Cai; Jianhong Wu

2010-01-01

83

Entangled-photons Raman spectroscopy  

NASA Astrophysics Data System (ADS)

It is well known that Raman spectroscopy suers from low signal-to-noise ratio (SNR). In this paper we oer a general framework based on quantum illumination that describes Rayleigh and Raman spectroscopy using an arbitrarily large number of entangled and non-entangled photons. Our objective is to analyze Rayleigh and Raman spectroscopy as a quantum information channel and study its asymptotic limits. In particular, if we consider quantum entanglement as an information resource, then the use of entangled photons oers an exponentially large improvement on the SNR of the Raman spectrometer. That is, the correlations embedded in quantum entanglement can be exploited to enhance the Raman signature of tested samples.

Lanzagorta, Marco

2012-05-01

84

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

85

High resolution\\/low wavenumber Fourier transform Raman spectroscopy with a rubidium vapor filter and a Ti:sapphire laser  

Microsoft Academic Search

High resolution\\/low wavenumber Fourier transform Raman spectra were obtained using a combination of a rubidium vapor filter and a Ti:sapphire laser. With this setup it is possible to measure FT-Raman spectra as close as 3 cm?1 to the Rayleigh line. This is demonstrated by the Raman spectra of crystalline sulfur, cadmium iodide, mercury iodide and osmiumtetroxide.

A. Nohe; G. Lermann; H. Schwoerer; W. Kiefer; J. Sawatzki; G. Surawicz

1997-01-01

86

Raman spectroscopy in magnetic fluids  

Microsoft Academic Search

In this work Raman spectroscopy was used to investigate uncoated magnetic fluids (UMF's) and coated magnetic fluids (CMF's). The coating agents were N-oleoylsarcosine, dodecanoic acid, and ethoxylated polyalcohol. The Raman probe is the hydroxyl (OH) group chemisorbed at the magnetic nanoparticle surface and the measurements were performed in the typical OH bending and OH stretching regions. The room temperature Raman

Paulo Cesar Morais; Sebastião William da Silva; Maria Aparecida Godoy Soler; Norbert Buske

2001-01-01

87

Laser Raman spectroscopy study of the zinc and bromide ion complex equilibrium in zinc\\/bromine battery electrolytes. [2M ZnBrâ and 1M KBr solution  

Microsoft Academic Search

Laser Raman spectroscopy was used to study the zinc and bromide ion complex equilibrium in zinc bromine battery model electrolytes. Solutions of zinc bromide with added KBr, HBr and N-methyl, N-ethyl morpholinium (MEM) bromide were examined and compared. Solutions studied ranged from 1 to 3 molar in zinc and from 2.5 to 8 molar in bromide. A typical Raman spectrum

P. G. Grimes; J. A. Larrabee

1985-01-01

88

Micro-Raman spectroscopy of refractive index microstructures in silicone-based hydrogel polymers created by high-repetition-rate femtosecond laser micromachining  

Microsoft Academic Search

Micro-Raman spectroscopy was used to study silicone-based hydrogel polymers after being modified by 800 nm, 27 fs laser pulses from a Ti:sapphire oscillator at 93 MHz repetition rate. When the irradiation con- ditions were below the optical breakdown threshold of the polymers, no significant changes in the Raman spec- tra and background fluorescence were observed even when refractive index changes

Li Ding; Luiz Gustavo Cancado; Lukas Novotny; Wayne H. Knox; Neil Anderson; Dharmendra Jani; Jeffrey Linhardt; Richard I. Blackwell; Jay F. Künzler

2009-01-01

89

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

90

Resonance Raman spectroscopy of red blood cells using near-infrared laser excitation.  

PubMed

Resonance Raman spectra of oxygenated and deoxygenated functional erythrocytes recorded using 785 nm laser excitation are presented. The high-quality spectra show a mixture of enhanced A(1g), A(2g), B(1g), B(2g), E(u) and vinyl modes. The high sensitivity of the Raman system enabled spectra from four oxygenation and deoxygenation cycles to be recorded with only 18 mW of power at the sample over a 60-minute period. This low power prevented photo-/thermal degradation and negated protein denaturation leading to heme aggregation. The large database consisting of 210 spectra from the four cycles was analyzed with principal components analysis (PCA). The PC1 loadings plot provided exquisite detail on bands associated with the oxygenated and deoxygenated states. The enhancement of a band at 567 cm(-1), observed in the spectra of oxygenated cells and the corresponding PC1 loadings plot, was assigned to the Fe-O(2) stretching mode, while a band appearing at 419 cm(-1) was assigned to the Fe-O-O bending mode based on previous studies. For deoxygenated cells, the enhancement of B(1g) modes at 785 nm excitation is consistent with vibronic coupling between band III and the Soret transition. In the case of oxygenated cells, the enhancement of iron-axial out-of-plane modes and non-totally symmetric modes is consistent with enhancement into the y,z-polarized transition a(iu)(pi)-->d(xz)+O(2)(pi(g)) centered at 785 nm. The enhancement of non-totally symmetric B(1g) modes in oxygenated cells suggests vibronic coupling between band IV and the Soret band. This study provides new insights into the vibrational dynamics, electronic structure and resonant enhancement of heme moieties within functional erythrocytes at near-IR excitation wavelengths. PMID:17151857

Wood, Bayden R; Caspers, Peter; Puppels, Gerwin J; Pandiancherri, Shveta; McNaughton, Don

2006-12-07

91

Laser irradiation and Raman spectroscopy of single living cells and chromosomes: Sample degradation occurs with 514.5 nm but not with 660 nm laser light  

Microsoft Academic Search

In Raman spectroscopic measurements of single cells (human lymphocytes) and chromosomes, using a newly developed confocal Raman microspectrometer and a laser excitation wavelength of 514.5 nm, degradation of the biological objects was observed. In the experiments high power microscope objectives were used, focusing the laser beam into a spot ? 0.5 ?m in diameter. At the position of the laser

G. J. Puppels; J. H. F. Olminkhof; G. M. J. Segers-Nolten; C. Otto; Mul de F. F. M; J. Greve

1991-01-01

92

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

PubMed

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

Bohlin, Alexis; Kliewer, Christopher J

2013-06-14

93

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

94

Spin-flip Raman laser  

Microsoft Academic Search

The properties of the spin-flip Raman laser (SFR laser) which depend on stimulated Raman scattering from mobile conduction electrons in InSb under an external magnetic field are presented. The essential parameters are derived from a macroscopic treatment of the stimulated Raman effect and the microscopic theory of the scattering cross section, and are compared with experimental results. Output pulse powers

H. G. Haefele

1974-01-01

95

Raman spectroscopy of carbon nanotubes  

Microsoft Academic Search

The use of Raman spectroscopy to reveal the remarkable structure and the unusual electronic and phonon properties of single wall carbon nanotubes (SWNTs) is reviewed comprehensively. The various types of Raman scattering processes relevant to carbon nanotubes are reviewed, and the theoretical foundations for these topics are presented. The most common experimental techniques used to probe carbon nanotubes are summarized,

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

2005-01-01

96

Time-resolving molecular vibration for microanalytics: single laser beam nonlinear Raman spectroscopy in simulation and experiment.  

PubMed

A single-beam implementation of coherent anti-Stokes Raman scattering (CARS) allows experimentally very much simplified and flexible approaches to time-resolved vibrational spectroscopy, with the additional benefit of microscopic spatial resolution. To achieve this, a broadband femtosecond laser is combined with a pulse shaper creating tailored pulse sequences by computer control. We discuss the theoretical foundations and technical issues of the technique in detail and show the successful implementation of different schemes for truly femtosecond time-resolved vibrational spectroscopy. Hereby, we elaborate all the details of the method shown earlier in a proof-of-principle study [Von Vacano and Motzkus, Opt. Comm., 2006, 264, 488] and greatly extend it by novel approaches relying on the use of identical double pulses or additional polarization control for background-free spectroscopy with superior robustness and signal-to-noise ratio. Perspectives and applications of the presented schemes for chemical microanalysis and high-contrast chemical imaging are examined. PMID:19791452

von Vacano, Bernhard; Motzkus, Marcus

2008-02-01

97

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...

98

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

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

99

Near-infrared Raman spectroscopy of single optically trapped biological cells  

Microsoft Academic Search

We report on the development and testing of a compact laser tweezers Raman spectroscopy (LTRS) system. The system combines optical trapping and near-infrared Raman spectroscopy for manipulation and identification of single biological cells in solution. A low-power diode laser at 785 nm was used for both trapping and excitation for Raman spectroscopy of the suspended microscopic particles. The design of

Changan Xie; Mumtaz A. Dinno; Yong-Qing Li

2002-01-01

100

Laser spectroscopy  

NASA Astrophysics Data System (ADS)

The primary purpose of this trip was to present two invited lectures at the Second Venezuelan Workshop on Laser Spectroscopy. This conference included essentially all of the Venezuelan researchers active in this area. In addition, four speakers from outside of Venezuela were invited to this meeting; two from the USA and two from the former Soviet Union (FSU). The primary topics of the meeting were fluorescence spectroscopy, photothermal spectroscopy, and laser - material interactions. Prior to the conference, three institutions in Caracas were visited (IVIC, USB, and UCV) and a presentation was given at UCV. The group of scientists and students attending the conference were interested in establishing collaborations with scientists in the USA.

Ramsey, J. M.

1992-12-01

101

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

NASA Astrophysics Data System (ADS)

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

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

2000-04-01

102

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

103

OPO CARS: coherent anti-Stokes Raman spectroscopy using tunable optical parametric oscillators injection-seeded by external-cavity diode lasers  

Microsoft Academic Search

Coherent anti-Stokes Raman spectroscopy (CARS) is performed on nitrogen gas using the signal wave from a pulsed ?-barium borate optical parametric oscillator (OPO), which has a passive ring cavity and is injection-seeded at its idler wavelength by a single-mode, external-cavity diode laser. The observed CARS linewidths are consistent with an optical bandwidth of 0.01 cm?1 for the continuously tunable OPO

G. W. Baxter; M. J. Johnson; J. G. Haub; B. J. Orr

1996-01-01

104

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

105

A cascaded silicon Raman laser  

Microsoft Academic Search

One of the major advantages of Raman lasers is their ability to generate coherent light in wavelength regions that are not easily accessible with other conventional types of lasers. Recently, efficient Raman lasing in silicon in the near-infrared region has been demonstrated, showing great potential for realizing low-cost, compact, room-temperature lasers in the mid-infrared region. Such lasers are highly desirable

Haisheng Rong; Shengbo Xu; Oded Cohen; Omri Raday; Mindy Lee; Vanessa Sih; Mario Paniccia

2008-01-01

106

Spin-flip Raman laser  

Microsoft Academic Search

The properties of the spin-flip Raman laser (SFR laser) which depend on stimulated Raman scattering from mobile conduction\\u000a electrons in InSb under an external magnetic field are presented. The essential parameters are derived from a macroscopic\\u000a treatment of the stimulated Raman effect and the microscopic theory of the scattering cross-section, and are compared with\\u000a experimental results. Output pulse powers as

H. G. Häfele

1974-01-01

107

Identification of species in a wet flue gas desulfurization and denitrification system by laser Raman spectroscopy  

Microsoft Academic Search

Raman spectra have been obtained for a number of intermediates and products of the reaction of nitrite iron with bisulphite ion. This is the first direct observation of all stable species in this reaction system. The dynamics of the species have been investigated at several nitrite and bisulphite concentrations that resemble those found in realistic power plant flue gas wet

David Littlejohn; Shih Ger Chang

1984-01-01

108

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 to the 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 along 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 translate the probe 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.; Blasi, Raymond J.; Archer, William B.

1998-07-28

109

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

110

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

111

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

112

Infrared and Raman Spectroscopy  

Microsoft Academic Search

\\u000a A brief introduction of applications of infrared and Raman spectroscopic techniques to zeolites, zeolite chemistry and the\\u000a chemistry that occurs in zeolite pores and channels is given in this chapter. The basic information, obtained by using these\\u000a techniques, of zeolite frameworks including isomorphous substitution, perturbation of zeolite frameworks by foreign cations,\\u000a and cation locations, zeolite surfaces including OH groups, acid

Xinsheng Liu

2010-01-01

113

Raman spectroscopy of thin films  

NASA Astrophysics Data System (ADS)

Raman spectroscopy was used in conjunction with x-ray diffraction and x-ray photoelectron spectroscopy to elucidate structural and compositional information on a variety of samples. Raman was used on the unique La 2NiMnO6 mixed double perovskite which is a member of the LaMnO3 family of perovskites and has multiferroic properties. Raman was also used on nanodiamond films as well as some boron-doped carbon compounds. Finally, Raman was used to identify metal-dendrimer bonds that have previously been overlooked. Vibrational modes for La2NiMnO6 were ascribed by comparing spectra with that for LaMnO3 bulk and thin film spectra. The two most prominent modes were labeled as an asymmetric stretch (A g) centered around 535 cm-1 and a symmetric stretch (B g) centered around 678 cm. The heteroepitaxial quality of La2NiMnO 6 films on SrTiO3 (100) and LaAlO3 (100) substrates were examined using the Raman microscope by way of depth profile experiments and by varying the thickness of the films. It was found that thin films (10 nm) had much greater strain on the LaAlO3 substrate than on the SrTiO3 substrate by examining the shifts of the Ag and the Bg modes from their bulk positions. Changes in the unit cell owing to the presence of oxygen defects were also monitored using Raman spectroscopy. It was found that the Ag and Bg modes shifted between samples formed with different oxygen partial pressures. These shifts could be correlated to changes in the symmetry of the manganese centers due to oxygen defects. Raman spectroscopy was used to examine the structural and compositional characteristics of carbon materials. Nanocrystalline diamond coated cutting tools were examined using the Raman Microscope. Impact, abrasion, and depth profile experiments indicated that delamination was the primary cause of film failure in these systems. Boron doped material of interest as catalyst supports were also examined. Monitoring of the G-mode and intensities of the D- and G-modes indicated that boron was successfully introduced into both a bulk powder fabricated in a quartz furnace using a BCl3/C6H 6 precursor and for a thin film (30 nm) deposited in a vacuum chamber using d.c. magnetron cosputtering. In addition to Raman, x-ray diffraction and x-ray photoelectron spectroscopy were used to verify boron-doping of the materials. Generation 4 Poly(amidoamine) dendrimers were used to form platinum and cobalt nanoparticles to form dendrimer-encapsulated nanoparticles (DENs). It was seen using both Raman and infrared spectroscopy that these metals bonded with the dendrimers after reduction. These studies highlight the efficacy of Raman in the study of a wide variety of materials to obtain both compositional and structural information.

Burgess, James Shaw

114

Polymer-capped fiber-optic Raman probe for non-invasive Raman spectroscopy  

PubMed Central

Advances in fiber optic probe design are moving Raman spectroscopy into the clinic, although there remain important practical problems. While much effort has been devoted to minimizing Raman and fluorescence background from fibers, less attention has been given to the need to generate reference Raman signals that can correct for variations in tissue albedo, which is important in quantifying changes in tissue composition. To address this shortcoming, we have developed a fiber optic probe that incorporates a fluorinated ethylene-propylene copolymer (FEP) cap at the end of each excitation fiber. Transmission of laser light through the transparent cap generates a 732 cm?1 Raman band whose intensity scales linearly with the laser power delivered to the tissue of interest. In our first design, the FEP cap functions as a waveguide with only a small insertion loss (~5%). Laser transmission through 1 mm of the polymer is sufficient to generate a usable reference Raman signal. We show the application of the probe to quantitative non-invasive Raman spectroscopy of animal tissues using rat leg phantoms as models. Ex-vivo Raman spectroscopy of excised rat tibia supports the use of the probe for spectroscopy of various tissues. These results provide proof of principle that the Raman probe can be used in multiple spectroscopic applications.

Okagbare, Paul I.; Morris, Michael D.

2012-01-01

115

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

116

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

PubMed

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

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

2013-07-01

117

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

ERIC Educational Resources Information Center

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

Chase, Bruce

2007-01-01

118

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

ERIC Educational Resources Information Center

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

Chase, Bruce

2007-01-01

119

A Review of the Theory and Application of Coherent Anti-Stokes Raman Spectroscopy (CARS)  

Microsoft Academic Search

Coherent anti-Stokes Raman spectroscopy (CARS) is a relatively new kind of Raman spectroscopy which is based on a nonlinear conversion of two laser beams into a coherent, laser-like Raman beam of high intensity in the anti-Stokes region. The emission is often many orders of magnitude greater than normal Raman scat- tering and, because of the coherent and anti-Stokes character of

W. M. Tolles; J. W. Nibler; J. R. McDonald; A. B. Harvey

1977-01-01

120

Laser irradiation and Raman spectroscopy of single living cells and chromosomes: Sample degradation occurs with 514. 5 nm but not with 660 nm laser light  

SciTech Connect

In Raman spectroscopic measurements of single cells (human lymphocytes) and chromosomes, using a newly developed confocal Raman microspectrometer and a laser excitation wavelength of 514.5 nm, degradation of the biological objects was observed. In the experiments high power microscope objectives were used, focusing the laser beam into a spot {approximately} 0.5 micron in diameter. At the position of the laser focus a paling of the samples became visible even when the laser power on the sample was reduced to less than 1 mW. This was accompanied by a gradual decrease in the intensity of the Raman signal. With 5 mW of laser power the events became noticeable after a period of time in the order of minutes. It is shown that a number of potential mechanisms, such as excessive sample heating due to absorption of laser light, multiple photon absorption, and substrate heating are unlikely to play a role. In experiments with DNA solutions and histone protein solutions no evidence of photo damage was found using laser powers up to 25 mW. No degradation of cells and chromosomes occurs when laser light of 660 nm is used. The most plausible explanation therefore seems to be that the sample degradation is the result of photochemical reactions initiated by laser excitation at 514.5 nm of as yet unidentified sensitizer molecules or complexes present in chromosomes and cells but not in purified DNA and histone protein samples.

Puppels, G.J.; Olminkhof, J.H.; Segers-Nolten, G.M.; Otto, C.; de Mul, F.F.; Greve, J. (Department of Applied Physics, University of Twente, Enschede (Netherlands))

1991-08-01

121

Raman-tweezers spectroscopy of single biological cells and organelles  

NASA Astrophysics Data System (ADS)

Raman tweezers, also called laser tweezers Raman spectroscopy (LTRS), is an instrument that combines optical tweezers and confocal Raman microscopy for simultaneous manipulation and analysis of single biological cells or organelles in a physiological solution without the need of introducing biochemical tags. The optical tweezers part of the LTRS system uses a tightly focused near-infrared beam to capture and immobilize a biological particle in a liquid medium by the gradient force. The Raman spectroscopy part can generate vibrational spectra of the trapped particle to provide composition and conformation information of molecules based on measuring molecular vibrations from the scattered light. In this talk, we will present the physical principle and instrumentation of optical tweezers and micro-Raman spectroscopy system. Applications in rapid detection and identification of microorganisms, sorting of living cells, and real-time measurement of the dynamical changes in biochemical properties of macromolecules within living cells, and detection of recombinant proteins in transgenic cells will be presented.

Li, Yongqing

2004-11-01

122

New Micro-Raman Spectroscopy Systems for High-Temperature Studies in the Diamond Anvil Cell  

Microsoft Academic Search

In order to measure high-quality Raman spectra at high temperature and pressure in either the resistance- or laser-heated diamond-anvil cell, we have developed two Raman systems at MIT, a dispersive and a nanosecond time-resolved Raman spectroscopy systems. The excitation source of the dispersive Raman system is an Ar\\/Kr mixed ion laser which has nine available laser lines with wavelengths between

S. Shim; R. Lamm; S. Rekhi; K. Catalli; J. Santillan; S. Lundin

2005-01-01

123

Tools for Robotic In Situ Optical Microscopy and Raman Spectroscopy on Mars  

Microsoft Academic Search

Robotic missions to Mars require remote diagnostic tools for detecting evidence of former life. Laser Raman spectroscopy is eminently suitable for this quest as its light-scattering principle permits nonintrusive analysis. Integration of Raman spectroscopy with optical microscopy correlates biochemical and morphological data. Vibrational Raman spectra identify component moieties of unknown target biomolecules such as pigments involved in photosynthesis and UV-protection.

C. H. Schoen; D. L. Dickensheets

2000-01-01

124

Raman spectroscopy at high pressure and high temperature. Phase transitions and thermodynamic properties of minerals  

Microsoft Academic Search

An outline of recent developments in Raman spectroscopy at high pressure, high temperature and combined high pressure and high temperature is presented. The instrumental and technical aspects of Raman spectroscopy, and coupling of diamond anvil cells and miniature furnaces to Raman microspectrometers are discussed. Some potential pitfalls, such as the thermal pressure in laser heated diamond anvil cells or the

P. Gillet

1996-01-01

125

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

126

Effect of the laser and light-emitting diode (LED) phototherapy on midpalatal suture bone formation after rapid maxilla expansion: a Raman spectroscopy analysis.  

PubMed

The aim of this study was to analyze the effect of laser or light-emitting diode (LED) phototherapy on the bone formation at the midpalatal suture after rapid maxilla expansion. Twenty young adult male rats were divided into four groups with 8 days of experimental time: group 1, no treatment; group 2, expansion; group 3, expansion and laser irradiation; and group 4, expansion and LED irradiation. In groups 3 and 4, light irradiation was in the first, third, and fifth experimental days. In all groups, the expansion was accomplished with a helicoid 0.020? stainless steel orthodontic spring. A diode laser (?780 nm, 70 mW, spot of 0.04 cm(2), t?=?257 s, spatial average energy fluence (SAEF) of 18 J/cm(2)) or a LED (?850 nm, 150 mW?±?10 mW, spot of 0.5 cm(2), t?=?120 s, SAEF of 18 J/cm(2)) were used. The samples were analyzed by Raman spectroscopy carried out at midpalatal suture and at the cortical area close to the suture. Two Raman shifts were analyzed: ?960 (phosphate hydroxyapatite) and ?1,450 cm(-1) (lipids and protein). Data was submitted to statistical analysis. Significant statistical difference (p???0.05) was found in the hydroxyapatite (CHA) peaks among the expansion group and the expansion and laser or LED groups. The LED group presented higher mean peak values of CHA. No statistical differences were found between the treated groups as for collagen deposition, although LED also presented higher mean peak values. The results of this study using Raman spectral analysis indicate that laser and LED light irradiation improves deposition of CHA in the midpalatal suture after orthopedic expansion. PMID:23430219

Rosa, Cristiane Becher; Habib, Fernando Antonio Lima; de Araújo, Telma Martins; Aragão, Juliana Silveira; Gomes, Rafael Soares; Barbosa, Artur Felipe Santos; Silveira, Landulfo; Pinheiro, Antonio L B

2013-02-21

127

From polarized to polarimetric Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is widely used in many areas of research and technology such as chemical analysis and material properties characterization. “Classic” Raman spectroscopy traditionally neglecting the polarization-of-light aspect, polarized Raman spectroscopy has been developed to further explore the possibilities offered by Raman scattering. Polarized Raman spectroscopy is based on the control of the linear polarization states of the incident and scattered radiations. The next step for enlarging the scope of the Raman scattering technique is to perform a complete polarimetric control of the scattered, as well as incident light. In this contribution, we present the implementation and the calibration of a Stokes polarimeter within the Raman scattering setup. We performed the calibration of the detection path of the setup and noticed that it modifies substantially the polarization state of the scattered light. In particular, the system introduced effects such as depolarization, diattenuation and retardance that need to be estimated before proceeding with quantitative polarization analysis.

Frigout, A.; Richert, M.; Ossikovski, R.

2010-06-01

128

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, Sze-Fong M.

1999-07-01

129

Monolithic integrated Raman silicon laser  

Microsoft Academic Search

We present a monolithic integrated Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide race-track ring resonator with an integrated p-i-n diode structure. Under reverse biasing, we achieved stable, single mode, continuous-wave (CW) lasing with output power exceeding 30mW and 10% slope efficiency. The laser emission has high spectral purity with a measured side mode suppression exceeding 70dB and laser

Haisheng Rong; Ying-Hao Kuo; Shengbo Xu; Ansheng Liu; Richard Jones; Mario Paniccia; Oded Cohen; Omri Raday

2006-01-01

130

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

2011-10-01

131

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).

Downes, Andrew; Elfick, Alistair

2010-01-01

132

Tip-Enhanced Raman Spectroscopy (TERS)  

Microsoft Academic Search

Tip-enhanced Raman spectroscopy is a vibrational spectroscopy with hitherto unprecedented sensitivity and spatial resolution.\\u000a Since the enhancement is mainly provided by the near-field excited at the apex of a suitable tip, TERS appears to be a widely\\u000a applicable spectroscopy and microscopy tool, in contrast to its parents, surface-enhanced Raman spectroscopy (SERS) and scanning\\u000a near-field optical microscopy (SNOM). TER scattering has

Bruno Pettinger; Fritz Haber

133

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

134

Pressure-tuning FT-Raman spectroscopy  

Microsoft Academic Search

Pressure-tuning dispersive Raman spectroscopy, using diamond anvil cells, has many of the common limitations of Raman spectroscopy such as low signal intensity, as well as photodecomposition and fluorescence of many samples. In the present investigations, the pressure-tuning experiment has been successfully coupled to an FT-Raman spectrometer using a microscope for sample alignment and measurement. The use of a holographic notch

Steven M. Barnett; Stephane H. Brienne; Ross D. Markwell; Nancy T. Kawai; Ian S. Butler; Denis F. Gilson; Antonin Vlcek

1994-01-01

135

Raman spectroscopy and imaging of graphene  

Microsoft Academic Search

Graphene has many unique properties that make it an ideal material for fundamental studies as well as for potential applications.\\u000a Here we review recent results on the Raman spectroscopy and imaging of graphene. We show that Raman spectroscopy and imaging\\u000a can be used as a quick and unambiguous method to determine the number of graphene layers. The strong Raman signal

Zhenhua Ni; Yingying Wang; Ting Yu; Zexiang Shen

2008-01-01

136

Raman Spectroscopy of Serum for Cancer Detection.  

National Technical Information Service (NTIS)

Laser induced auto- fluorescence and Raman spectra of serum from cancerous and normal people are measured and analyzed. Three Raman peaks were consistently observed from normal blood serum emission using 488.0nm and 514.5nm excitation of an Ar-ion laser w...

X. Li H. Jin

2001-01-01

137

Electrochemical and laser raman spectroscopy studies of stainless steel in 0. 15M NaC1 solution  

SciTech Connect

This paper reports on potentiodynamic polarization curves measured by Type AISI 304 and 316 stainless steels in 0.15M NaCl solution at 4, 20, and 40[degrees]C. The pitting potentials decreased with increasing temperature. A positive effect on the inhibition of passivity breakdown was found in the presence of molybdenum. Surface enhanced Raman spectroscopy (SERS) was carried out on AISI 316 stainless steel to identify the species present on the electrode surface as a function of potential. Results indicate the corrosion films to be highly disordered and most likely to consist of a mixture of the oxides and hydroxides of the component elements of the stainless steel. The potential dependence of the spectra may reflect the behavior of iron, which is the most abundant component in the alloy and most probably in the film.

erreira, M.G.S.; Mourae Silva, T.; Catarino, A. (Dept. of Chemical Engineering, Inst. Superior Tecnico, 1096 Lisboa Codex (Portugal)); Pankuch, M.; Melendres, C.A. (Materials Science and Chemical Technology Div., Argonne National Lab., Argonne, IL (United States))

1992-11-01

138

Measurement of DNA adducts using surface-enhanced Raman spectroscopy  

SciTech Connect

Hazardous pollutants emitted from energy-related technologies, chemical industries, or waste materials are of increasing public concern because of their potential adverse health effects. Many pollutants have chemical groups of toxicological importance that can be characterized and detected by Raman spectroscopy. Raman spectroscopy, however, has not been widely used in trace organic detection, even though the information contained in a Raman spectrum is valuable for chemical identification. One limitation of conventional Raman spectroscopy is its low sensitivity, which often necessitates the use of powerful and costly laser sources for sample excitation. Raman spectroscopists have recently been able to analyze dilute biological samples as a result of enhancements in the Raman scattering cross section by factors up to 10[sup 10] when a compound is adsorbed on or near a special electron-conducting surface. These spectacular enhancement factors of the normally weak Raman scattering process help overcome the low sensitivity of Raman spectroscopy through a combination of electromagnetic and chemical interactions between the analyte molecule and the surface. The technique associated with this phenomenon is known as surface-enhanced Raman scattering spectroscopy (SERS). The special conductive surface responsible for the scattering enhancement is referred to as a SERS substrate. For the past few years we have developed the SERS technique, using practical SERS-active substrate materials based on silver-coated microspheres deposited on glass. A wide variety of biomarkers have been investigated, including benzo[a]pyrene, dibenz[a,h]anthracene epoxides, 1, N[sup 9]-ethenoadenine, 3, N[sup 4]-ethenocytosine, and other substances. The experimental results are of great analytical interest, since these chemicals are difficult to detect by other techniques, such as luminescence spectroscopy, because of the weak luminescence quantum yields of these DNA adducts. 7 refs., 4 figs.

Helmenstine, A.; Uziel, M.; Vo-Dinh, T. (Oak Ridge National Lab., TN (United States))

1993-01-01

139

NIR-FT/RAMAN SPECTROSCOPY FOR NUTRITIONAL CLASSIFICATION OF CEREAL FOODS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The classification of cereals using near-infrared Fourier transform Raman (NIR-FT/Raman) spectroscopy was accomplished. A total of 120 cereal based food samples were prepared and ground. Samples were scanned on a Nicolet Raman instrument with a 1064 nm (NIR) excitation laser using 500mW of power and...

140

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

141

Femtosecond broadband stimulated Raman spectroscopy: Apparatus and methods  

PubMed Central

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

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

2005-01-01

142

Laser cavitation and Raman pulse compression  

Microsoft Academic Search

The cavitation and cavity are produced near the focus when high power laser is focused into the liquid, and Raman seed source is generated in this cavity, which will give a backward and forward Raman light pulse due to amplification.

Shaoxian Meng; Zhongmin Gu; Jiran Zhao; Haiwu Yu

1996-01-01

143

Investigation of optical homogeneity and photorefractive properties of lithium-niobate single crystals by the Raman-spectroscopy and laser-conoscopy methods  

NASA Astrophysics Data System (ADS)

Photorefractive properties and structural and optical homogeneity of (1) LiNbO3:Cu crystals ([Cu] = 0.015 mas %) grown from a congruent melt, (2) nominally pure stoichiometric crystals grown from a melt with 58.6 mol % of Li2O (LiNbO3stoich), and (3) nominally pure congruent crystals (LiNbO3congr) have been studied using the Raman-spectroscopy method with excitation in the UV, visible, and near-IR ranges; the laser-conoscopy method; and the electron paramagnetic resonance-spectroscopy method. In optically uniaxial LiNbO3 crystals, a weak optical biaxiality has been revealed, which is attributed to an insignificant deformation of the optical indicatrix. This deformation can be caused both by the initial structural inhomogeneity of crystals and by the photorefractive effect. It has been shown that, under the action of light, charge exchange of copper cations Cu2+ ? Cu+ takes place in the crystal LiNbO3:Cu ([Cu] = 0.015 mas %). The LiNbO3:Cu crystal exhibits photorefractive properties not only because of the occurrence of intrinsic defects with electrons localized at them, as is the case with the LiNbO3stoich and LiNbO3congr crystals, but also due to the charge exchange of copper cations under the action of the laser radiation.

Sidorov, N. V.; Palatnikov, M. N.; Yanichev, A. A.; Gabain, A. A.; Pikoul, O. Yu.; Smirnov, A. N.

2013-10-01

144

Axillary lymph node analysis using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Raman Spectroscopy is an optical diagnostic technique applied in this study to classify axillary lymph nodes from breast cancer patients as positive or negative for metastases. The mapping technique in this study is 81% sensitive and 97% specific for the correct classification of positive lymph nodes. Raman spectral images of lymph node sections are constructed to facilitate interpretation of tissue features.

Smith, Jenny; Christie-Brown, Jonathan; Sammon, Alastair; Stone, Nicholas

2004-07-01

145

Application of infrared and Raman spectroscopy in paint trace examination.  

PubMed

Raman spectroscopy has proved to be a promising technique in forensic examinations, where optical microscopy, micro-infrared spectroscopy, and microspectrophotometry in the visible and UV range are used for identification and differentiation between paint traces. Often no organic pigments are detected using Fourier transform infrared spectroscopy, because their content in a trace is usually undetectable. Application of a micro-Raman spectrometer equipped with several excitation lasers helps forensic experts in paint analysis enabling identification of main pigments. Three cases concerning comparative examination of car paint are discussed in detail. The comparison of Raman spectra of paint chips found on clothing of a victim or smears found on body of a damaged car to these of paint chips originated from the suspected car enabled us to identify the car involved in the accident. When no comparative material is available, the method can be useful in establishing the color and make of the car. PMID:23865525

Zi?ba-Palus, Janina; Trzci?ska, Beata M

2013-07-18

146

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

PubMed

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 the broadband dye laser used for CARS was shifted to the deep red to avoid interferences with the LRS signals located in the visible region. First experimental results from a vaporizing propane spray using an engine injection system are shown. PMID:16729111

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

2006-06-15

147

Advancing Raman spectroscopy for lignin applications  

Treesearch

Science.gov - We Participate ... Description: Over the last 25 years, lignin applications of Raman spectroscopy have come a long way. ... research although where appropriate examples are included from published work of other researchers.

148

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...

149

CHEMOMETRIC PREDICTIONS OF GRAIN FLOUR ATTRIBUTED USING NIR-FT/RAMAN SPECTROSCOPY  

Technology Transfer Automated Retrieval System (TEKTRAN)

NIR-FT/Raman spectroscopy can give comparable to improved chemometric results versus infrared absorbance spectroscopy for prediction of grain flour attributes, provided proper attention is given to data collection and pre-processing. An NIR laser is generally required for Raman excitation when inve...

150

Single-beam coherent Raman spectroscopy and microscopy via spectral notch shaping  

Microsoft Academic Search

Raman spectroscopy is one of the key techniques in the study of vibrational modes and molecular structures. In Coherent Anti-Stokes Raman Scattering (CARS) spectroscopy, a molecular vibrational spectrum is resolved via the third-order nonlinear interaction of pump, Stokes and probe photons, typically using a complex experimental setup with multiple beams and laser sources. Although CARS has become a widespread technique

Ori Katz; Jonathan M. Levitt; Eran Grinvald; Yaron Silberberg

2010-01-01

151

Occlusal caries detection using polarized Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

Ionita, I.; Bulou, A.

2008-03-01

152

Raman studies of pulse repetition effect in laser processing of Si  

Microsoft Academic Search

It is meaningful to avoid irreversible changes in laser processing of silicon wafer and find out the cause to which the laser induced damage threshold is decreased along with increasing frequency. We investigated the PRE in laser irradiation on c-Si wafer by Raman spectroscopy. Time- resolved Raman spectrometer was developed based on holographic notch filter, optical fiber and optical multichannel

H. Qiu; Yongfeng Lu

1999-01-01

153

Raman spectroscopy using time-correlated photon-counting detection  

NASA Astrophysics Data System (ADS)

A highly sensitive, shot-noise-limited Raman signal acquisition is achieved using frequency-time transformation in a single-mode fiber and time-correlated photon counting system. To spectrally disperse Raman signal excited by a picosecond laser pulse, the light is directed into a sufficiently long single-mode fiber. The output end of the fiber is coupled into a time-gated photon multiplier tube (PMT). Due to a frequency-time conversion provided by the fiber core, photons of different frequencies experience different transient times. In this way, by measuring the photons' arrival time, Raman peaks can be recorded and separated. Moreover, in some cases the fluorescence background can be eliminated from Raman signals due to its much longer life-time. Consequently, a fluorescent background free Raman spectrum can be attained using the time-correlated photon-counting Raman spectroscopy. In this report, by using a 400m SM600 single-mode fiber and a Hamamatsu R3809U-50 PMT, we demonstrate the Raman spectrum of dimethyl sulfoxide excited by a short-pulsed laser.

Meng, Zhaokai; Cheng, Shuna; Petrov, Georgi I.; Jo, Javier A.; Yakovlev, Vladislav V.

2013-03-01

154

Real-time Raman spectroscopy of optically trapped living cells and organelles  

Microsoft Academic Search

We report on real-time Raman spectroscopic studies of optically trapped living cells and organelles using an inverted confocal laser-tweezers-Raman-spectroscopy (LTRS) system. The LTRS system was used to hold a single living cell in a physiological solution or to hold a functional organelle within a living cell and consequently measured its Raman spectra. We have measured the changes in Raman spectra

Changan Xie; Charles Goodman; Mumtaz A. Dinno; Yong-Qing Li

2004-01-01

155

Raman Under Nitrogen. The High-Resolution Raman Spectroscopy of Crystalline Uranocene, Thorocene, and Ferrocene  

SciTech Connect

The utility of recording Raman spectroscopy under liquid nitrogen, a technique we call Raman Under Nitrogen (RUN), is demonstrated for ferrocene, uranocene and thorocene. Using RUN, low temperature (liquid nitrogen cooled) Raman spectra for these compounds exhibit higher resolution than previous studies and new vibrational features are reported. The first Raman spectra of crystalline uranocene at 77 K are reported using excitation from argon (5145 ) and krypton (6764 ) ion lasers. The spectra obtained showed bands corresponding to vibrational transitions at 212, 236, 259, 379, 753, 897, 1500, and 3042 cm-1 , assigned to ring-metal-ring stretching, ring-metal tilting, out-of-plane CCC bending, in-plane CCC bending, ring-breathing, C-H bending, CC stretching and CH stretching, respectively. The assigned vibrational bands are compared to those of uranocene in THF and thorocene. All vibrational frequencies of the ligands, except the 259 cm-1 out-of-plane CCC bending mode, were found to increase upon coordination. A broad polarizable band centered about {approx}460 cm-1 was also observed. The 460 cm-1 band is greatly enhanced relative to the vibrational Raman transitions with excitation from the krypton ion laser, which is indicative of an electronic resonance Raman process as has been shown previously. The electronic resonance Raman band is observed to split into three distinct bands at 450, 461 and 474 cm-1 with 6764 excitation. Relativistic density functional theory (DFT) is used to provide theoretical interpretations of the measured spectra.

Hager, J S.; Zahardis, James; Pagni, Richard M.; Compton, Robert N.; Li, Jun

2004-02-08

156

Estimating atomic sizes with Raman spectroscopy.  

PubMed

We demonstrate a technique to determine the Van der Waals radius of iodine atoms using Raman spectroscopy. The iodine diatomic molecules are diffused into the nano-scale channels of a zeolite single crystal. We found their polarized Raman spectroscopy, which corresponds to iodine molecule's vibrational motion along the direction of molecular axis, is significantly modified by the interaction between the iodine molecules and the rigid frame of the crystal's nano-channels. From the number of excitable vibration quantum states of the confined iodine molecules determined from Raman spectra and the size of the nano-channels, we estimate the iodine atomic radius to be 2.10±0.05 Å. It is the first time that atomic sizes, which are far beyond the optical diffraction limit, have be resolved optically using Raman spectroscopy with the help of nano-scale structures. PMID:23508118

Wang, Dingdi; Guo, Wenhao; Hu, Juanmei; Liu, Fang; Chen, Lisheng; Du, Shengwang; Tang, Zikang

2013-01-01

157

Investigation into the deformation of carbon nanotubes and their composites through the use of Raman spectroscopy  

Microsoft Academic Search

The deformation micromechanics of single-walled carbon nanotube (SWNT) and multi-walled carbon nanotube (MWNT) particulate nanocomposites has been studied using Raman spectroscopy. SWNTs prepared by two different methods (pulsed-laser and arc-discharge) and MWNTs have been used as reinforcement for a polymer matrix nanocomposite. The carbon nanotubes exhibit well-defined Raman peaks and Raman spectroscopy has been used to follow their deformation. SWNTs

C. A. Cooper; R. J. Young; M. Halsall

2001-01-01

158

Raman spectroscopy and Raman imaging for early detection of cancer  

Microsoft Academic Search

Raman spectroscopy is a powerful technique as it provides fundamental information about vibrational modes of a system. Eigenvalues of these modes are very sensitive to the strength of the chemical bonds and perturbations caused by the environment, particularly charge distribution and alterations in the dipole strength of the system. All these parameters are profoundly modified during the tumor formation process

Narahari V. Joshi; Angel Ortega; Jose Maria Estrela

2004-01-01

159

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

160

Designing of Raman lasers with Bragg mirrors  

NASA Astrophysics Data System (ADS)

In this paper, a method of designing a Raman laser structures with Bragg mirrors used to coupling pump signal, forming a resonator and lead-out laser signal outside is presented. The Raman laser is SOI waveguide structure (such as "rib," i.e. ridge waveguide) with built-in reverse biased p-i-n diode, wherein the optical gain is generated by stimulated Raman effect in the waveguide. Our way of designing is based on the effective refractive index method. Design of Raman laser with Bragg mirrors consists of two main stages: the first step is the choice of the optimum size and shape of the rib waveguide; the second step is the selection of Bragg gratings parameters. Our method of designing such Raman laser structures is a design tool, which uses analytical dependences and allows specifying optimal geometric parameters of one mode laser.

Mossakowska-Wyszy?ska, Agnieszka; Tyszka-Zawadzka, Anna; Mroczy?ski, Robert; Beck, Romuald B.; Szczepa?ski, Pawe?

2013-07-01

161

Cone penetrometer fiber optic raman spectroscopy probe assembly  

DOEpatents

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

Kyle, Kevin R. (Brentwood, CA); Brown, Steven B. (Livermore, CA)

2000-01-01

162

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

163

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

Microsoft Academic Search

The Raman spectra of fluoro-organic compounds show specific emission bands for carbon-fluorine bonds in the range 500- 800 wave numbers (cm-1)). With very limited exceptions, biological materials do not contain carbon- fluorine bonds. Fluoro-organic compounds introduced into biological samples can be detected by a Raman emission signal. Normal mode C-F bond bands are observed: (1) at 710- 785 cm -1

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

1999-01-01

164

Serial Raman spectroscopy of particles trapped on a waveguide.  

PubMed

We demonstrate that Raman spectroscopy can be used to characterize and identify particles that are trapped and propelled along optical waveguides. To accomplish this, microscopic particles on a waveguide are moved along the waveguide and then individually addressed by a focused laser beam to obtain their characteristic Raman signature within 1 second acquisition time. The spectrum is used to distinguish between glass and polystyrene particles. After the characterization, the particles continue to be propelled along the straight waveguide. Alternatively, a waveguide loop with a gap is also investigated, and in this case particles are held in the gap for characterization before they are released. PMID:23481754

Løvhaugen, Pål; Ahluwalia, Balpreet Singh; Huser, Thomas R; Hellesø, Olav Gaute

2013-02-11

165

Airborne chemistry coupled to Raman spectroscopy.  

PubMed

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

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

2003-05-01

166

Nano-Raman Spectroscopy is Reaching Semiconductors  

NASA Astrophysics Data System (ADS)

We have demonstrated that scanning nano-Raman spectroscopy (SNRS), also known as tip enhanced Raman spectroscopy (TERS), with side illumination optics can be effectively used for analysis of silicon-based structures at the nanoscale. Despite the disadvantages of side illumination optics, such as difficulties in optical alignment and shadowing by the tip, it has the critical advantage that it may be used for the analysis of non-transparent samples. A key criterion for making SNRS effective for imaging Si samples is the optimization of the contrast between near-field and far-field (background) Raman signals, which improves by an order of magnitude by optimizing the incident and scattering polarization scheme. The resulting nano-Raman images of semiconducting structures yield a spatial resolution ~20 nm.

Hartschuh, R. D.; Lee, N.; Kisliuk, A.; Maguire, J. F.; Green, M.; Foster, M. D.; Sokolov, A. P.

2007-09-01

167

Application of the Raman Spectroscopy to Identification of Titanomagnetites  

NASA Astrophysics Data System (ADS)

The titanomagnetite-magnetite series serves as important magnetic carriers in paleomagnetic studies. Commonly Curie points are used to determine the composition of these magnetic phases. However, Curie points generally reflect bulk rock properties and do not provide insight for individual grains. Determination of individual Fe-Ti oxide grains can be done by petrography or with electron microprobe techniques. In contrast to these methods, which require special sample preparation, Raman spectroscopy can be done with minimal preparation. We have therefore investigated the Raman spectra for magnetite, TM20, TM40, and TM60, so that we can identify titanomagnetites with different Ti content in rocks. The samples were prepared following methods of Wanamaker and Moskovitz (1994). The Ti concentrations were verified by thermomagnetic analysis (Gilder and LeGoff, 2005). The Raman spectra were obtained with WITec Raman Confocal Microscope 200 using a green laser. Slight shifts and changes in relative intensities of the peaks at the characteristic wavelengths of the Raman spectra that correspond to different molecular vibrations were observed. These changes can serve to identify the composition of individual titanomagnetite grains. It also enables mapping of the variation of the composition within grains and the distribution of compositions of grains within a rock. We have applied the technique to synthetic Martian samples and found relatively uniform compositions between different grains. In contrast, variable oxide compositions are discerned using the Raman spectroscopy in natural basalts erupted from East Maui volcano.

Tatsumi-Petrochilos, L.; Gilder, S. A.; Zinin, P.; Hammer, J. E.; Fuller, M. D.

2008-12-01

168

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

169

Two-frequency fibre Raman laser  

SciTech Connect

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

Paramonov, Vladimir M; Kurkov, Andrei S; Medvedkov, O I; Grukh, Dmitrii A; Dianov, Evgenii M [Fiber Optics Research Center, Russian Academy of Sciences, Moscow (Russian Federation)

2004-03-31

170

Raman Spectroscopy Databases | Spectra Databases  

NSDL National Science Digital Library

This site is a clearinghouse of vibrational frequencies and Raman, mass, fluorescence, neutron scattering and infrared spectra. Both organic and mineral databases are included. The site features free access from both university and industry sources.

Spectroscopynow.com

171

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

Microsoft Academic Search

The aim of this study was to evaluate, through Raman spectroscopy, the repair of complete tibial fracture in rabbits fixed with wire osteosynthesis - WO, treated or not with infrared laser light (lambda 780nm, 50mW, CW) associated or not to the use of HATCP and GBR. Surgical fractures were created under general anesthesia (Ketamine 0.4ml\\/Kg IP and Xilazine 0.2ml\\/Kg IP),

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

2011-01-01

172

Laser Raman Scattering Studies of Crystals.  

National Technical Information Service (NTIS)

Laser excited Raman scattering has been explored as a technique for studying crystals containing impurities, particularly the rare-earth doped crystals widely used as laser materials. Spectra obtained with both an A(+)4880 A laser and a He-Ne 6328 A laser...

H. Z. Cummins

1966-01-01

173

Raman spectroscopy and Raman imaging for early detection of cancer  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is a powerful technique as it provides fundamental information about vibrational modes of a system. Eigenvalues of these modes are very sensitive to the strength of the chemical bonds and perturbations caused by the environment, particularly charge distribution and alterations in the dipole strength of the system. All these parameters are profoundly modified during the tumor formation process nad hence Raman technique could be a unique and also a direct approach for evaluating tumor genesis at early stages. for this pupose the present investigation was carried out. We used cultured wild type and c-ras transformed NIH 3T3 fibroblast. The samples were treated with methyl alcohol solution ina conventional manner and then Raman spectra nad images were obtained by a specially developed confocal Raman microscope. The present results reveal differences between both cell types in the spectral details as well as in the morphology. Raman images are able to detect the exact site where cancer-related changes have taken place. These results clearly indicate the superiority of the present technique over conventional methods such as images obtained by X-rays or Nuclear Magnetic Resonance (NMR). Moreover, unlike other approaches, Raman images detect alterations at the submicron level rather than in the centimeter or millimeter range. Being an optical method it can be applied in vivo as a non-invasive technique potentially useful to early detection of cancer (particularly easy accessible cancers such as those of the skin and the digestive tract). The obtained resulsts suggest the great potential of Raman imaging in premature clinical diagnostic approaches.

Joshi, Narahari V.; Ortega, Angel; Estrela, Jose Maria

2004-06-01

174

High-resolution stimulated Raman spectroscopy  

SciTech Connect

The development of stimulated Raman spectroscopy over the past four years has clearly established the technique as a valuable tool in gas-phase Raman studies. In this brief article we have traced that development, detailed the capabilities of the stimulated Raman spectrometer, and surveyed a variety of applications of the system to problems in the gas phase. SRS is clearly most attractive in ultra-high-resolution (< 0.01 cm/sup -1/) studies that are beyond the reach of spontaneous Raman spectroscopy. Collision broadening effects dictate that such studies be performed at low pressures in order to maximize sensitivity. Currently, sample pressures below approximately 5 Torr are required in order to achieve linewidths approaching our 0.002 cm/sup -1/ instrumental resolution. Sensitivity considerations have thus limited our studies at these low pressures to relatively strong Raman scattering modes. It is our expectation that in the near future the introduction of higher-power sources and a multi-pas cell will significantly change this situation by increasing the overall sensitivity of SRS by at least two orders of magnitude. This should open up a much wider range of possible applications, which should, in turn, establish SRS as the standard for high-resolution Raman studies. 43 references.

Esherick, P.; Owyoung, A.

1982-01-01

175

Coherent Raman spectro-imaging with laser frequency combs.  

PubMed

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

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

2013-10-17

176

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

177

High-resolution broadband N2 coherent anti-Stokes Raman spectroscopy: comparison of measurements for conventional and modeless broadband dye lasers  

NASA Astrophysics Data System (ADS)

We have performed high-resolution N2 coherent anti-Stokes Raman spectroscopy (CARS) measurements using a modeless dye laser (MDL) as the Stokes beam source to determine the effects of a reduction in mode noise on the accuracy and precision of the method. These results are compared with previous research that employed a conventional broadband dye laser (CBDL) as the Stokes beam source. A new spectral-fitting procedure was developed to avoid starting-point bias in the least-squares fitting results, which possibly had altered the previous measurements. Single-shot measurements of pressure were performed in a static-pressure vessel over the range of 0.1-4.0 atm to examine the pressure sensitivity of the technique. The precision of these measurements is a measure of the baseline noise level of the system, which sets the detection limit for flow-field pressure fluctuations. Centerline measurements of pressure and temperature in an underexpanded jet (Mj = 1.85) were also used to determine the performance of the technique in a compressible flow field. Our study represents the first known application, to our knowledge, of a MDL CARS system in a low-temperature, low-pressure supersonic environment. Improvements in accuracy for mean single-shot measurements and increased precision were found for pressure vessel conditions above 1.0 atm. For subatmospheric pressure vessel conditions (0.1-1.0 atm) and the underexpanded jet measurements, there was a decrease in accuracy and precision compared with the CBDL results. A comparison with the CBDL study is included, along with a discussion of the MDL system behavior.

Kuehner, Joel P.; Woodmansee, Mark A.; Lucht, Robert P.; Dutton, J. Craig

2003-11-01

178

High performance resonance Raman spectroscopy using volume Bragg gratings as tunable light filters  

Microsoft Academic Search

We designed a near infrared tunable resonance Raman spectroscopy system based on a tandem of thick volume Bragg gratings (VBGs). VBGs are here the constituents of two light filtering units: a tunable laser line filter (LLF) and a tunable notch filter (NF). When adapted in a micro-Raman setup with a single stage monochromator (1800 gr\\/mm grating), the tandem of LLF

Matthieu Paillet; François Meunier; Marc Verhaegen; Sébastien Blais-Ouellette; Richard Martel

2010-01-01

179

High Performance Resonance Raman Spectroscopy Using Volume Bragg Gratings as Tunable Light Filters  

Microsoft Academic Search

We designed a near infrared tunable resonance Raman spectroscopy system based on a tandem of thick volume Bragg gratings (VBGs). VBGs are here the constituents of two light filtering units: a tunable laser line filter (LLF) and a tunable notch filter (NF). When adapted in a micro-Raman setup with a single stage monochromator (1800 gr\\/mm grating), the tandem of LLF

Marc Verhaegen; Matthieu Paillet; François Meunier; Sébastien Blais-Ouellette; Richard Martel

2010-01-01

180

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

2011-10-01

181

On Raman spectroscopy of zirconium oxide films  

Microsoft Academic Search

Using Raman spectroscopy, we studied samples of pure tetragonal and monoclinic zirconia powders, and oxide film developed at 400°C in steam (autoclave) on Zircaloy-4 with various tin contents. We analyze the absolute intensities of the bands and background, as well as the position of the bands. All these parameters bring some surprising evolution with tin content and oxidation time, relatively

P. Barberis; T. Merle-Méjean; P. Quintard

1997-01-01

182

Raman Spectroscopy of Bone and Cartilage  

NASA Astrophysics Data System (ADS)

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

Morris, Michael

183

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

184

Hyper-Raman spectroscopy of Earth related materials  

NASA Astrophysics Data System (ADS)

Raman and infrared spectroscopy proved extremely successful in obtaining structural information and thermodynamic data on samples under high pressure conditions in a diamond anvil cell [1,2]. With substantial advances in CCD detector technology and the possibility to focus visible laser light down to several microns, Raman spectroscopy can nowadays be regarded one of the standard techniques for diamond anvil cell investigations. Nevertheless, Raman scattering suffers from often strong fluorescence and the strong Raman signal of the diamonds. Infrared spectroscopy is limited by the sample size and the diffraction limit of mid- or far-infrared radiation. With increasing pressure, diamonds also show strong infrared activity, which can interfere with the signal from the sample. Detectors in the mid- and far-infrared are inherently noisy, often leading to low signal-to-noise ratios for infrared measurements. With new techniques and instrumentation available, such as low noise CCD cameras and stable diode-pumped solid state laser systems, more demanding techniques become feasible as well. Especially hyper-Raman scattering, a nonlinear optical variant of infrared spectroscopy, can be used on a more routine basis for the first time. Pioneering work in the 70s and 80s have explored some of the capabilities of Hyper-Raman spectroscopy [3]. Unlike infrared spectroscopy, Hyper-Raman is not limited by the diffraction limit of mid- or far-infrared radiation, typically restricting the lower frequency limit to several hundred wave numbers. The major advantages of hyper-Raman are essentially background free spectra and the use of wavelengths in the near-infrared and visible, making possible micro focusing and taking advantage of high efficiencies, low noise, and smooth wavelength dependencies of CCD detectors. Hyper-Raman does not suffer from saturation caused by strong absorption in the infrared and is therefore less sensitive to surface effects. For centrosymmetric materials conventional Raman and hyper-Raman are complimentary. In many cases the combined information of both techniques can reveal all the vibrational information of a material. This information can be used to calculate thermodynamic properties, to identify mineral phases ('finger-printing'), or to investigate the dynamics related to phase transitions ('soft-modes'). First results on planetary materials will be presented, including MgO and stichovite. Corundum as another possible high pressure transmitting material is characterized as well. Further measurements are underway, including MgSiO3 and CaSiO3 perovskite. [1] A. M. Hofmeister, in: Infrared Spectroscopy in Geochemistry, Exploration Geochemistry, and Remote Sensing, Vol. 33 (ed. P. K. King, M. S. Ramsey, and G. A. Swayze), Mineralogical Society of Canada (2004) [2] P. F. McMillan, R. J. Hemley, and P. Gillet, in : Mineral Spectroscopy: A Tribute to Roger G. Burns, Vol. 5 (ed. D. Dyar, C. McCammon, and M. W. Schaefer), The Geochemical Society Special Publication (1996). [3] H. Vogt, in: Topics in Applied Physics, Vol. 50, Light scattering in solids II (ed. M. Cardonna and G. Guentherodt), Springer-Verlag, Heidelberg, New York (1982).

Hellwig, H.

2004-12-01

185

[Study of Raman spectroscopy of optically trapped human red blood cell affected by direct current].  

PubMed

Laser tweezers Raman spectroscopy (LTRS) system is a combination of spectroscopy and laser tweezers; It is a new method of studying cells; It can trap single living cell and make Raman spectrum of single living cell. From the positions, intensities, and line widths of the Raman peaks in the spectra, we can get useful information about composition, structure and interactions of complexes inside the living cells. External agents may change cell's physiological state and this changed information can also be got from Raman spectra. This article is a study of Raman spectra of human red blood cell (RBC) affected by different intensity direct current (DC); from the result, distinct change of Raman spectra of RBC have been got. These changes characterize the changes of the internal information of the cells. This article give some academic reference of physical therapy using DC in the level of molecule. PMID:17591270

Yue, Liangyue; Wang, Guiwen; Fang, Ling; Yao, Huilu; Yuan, Zhigang; Mo, Hua

2007-04-01

186

Tissue measurement using 1064 nm dispersive Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2013-03-01

187

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

188

Bulk and surface-enhanced Raman spectroscopy of nitrogen-doped ultrananocrystalline diamond films  

Microsoft Academic Search

Ultrananocrystalline diamond films (UNCD) grown in an Ar-rich microwave plasma with nitrogen gas added in amounts of 0-25% were studied by Raman spectroscopy using 514.5 and 413.1 nm laser excitation. Besides the Raman spectra of diamond, the first and second order Raman scattering of disordered graphite and polyacetylene were detected and analyzed for samples with different nitrogen content. With surface

I. I. Vlasov; V. G. Ralchenko; E. Goovaerts; A. V. Saveliev; M. V. Kanzyuba

2006-01-01

189

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

Microsoft Academic Search

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

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

2007-01-01

190

Raman imaging and spectroscopy of single functional erythrocytes: a feasibility study  

NASA Astrophysics Data System (ADS)

Hemoglobin (Hb) within single erythrocytes (red blood cells), adsorbed on poly-lysine coated glass surfaces, was studied using resonance Raman spectroscopy and global Raman imaging. The erythrocytes were found to be sensitive to both surface adsorption and to the laser light. Topological changes of the cell membrane were observed immediately after cell adsorption in Raman images. We observed a photo-induced increase of the fluorescence background occurring simultaneously with a decrease in the Hb Raman signal. Concurrent changes in Raman spectra revealed a conversion of oxy-Hb to the met-Hb state. However, at a low accumulated photon dose, the preparation method enabled the recording of Raman spectra during the oxygenation cycle of a single red blood cell in buffer, which shows that Hb was in an in-vivo environment. Thus, Raman spectroscopy of functional Hb in isolated red blood cells is feasible.

Ramser, Kerstin; Bjerneld, Erik J.; Fant, Camilla; Kaell, Mikael

2002-03-01

191

Monolithic integrated Raman silicon lasers and amplifiers  

Microsoft Academic Search

In this paper, a chip-scale Raman silicon laser and amplifier based on a ring resonator architecture are presented. Lasing threshold and efficiency are significantly improved from the previous experiments. Much lower pump power and smaller foot print are needed for the ring resonator amplifier compared to Raman amplifier in linear configuration due to the resonance enhancement effect. The ring resonator

Haisheng Rong; Shengbo Xu; Ying-Hao Kuo; V. Sih; M. Paniccia; O. Cohen; O. Raday

2007-01-01

192

Raman spectroscopy in head and neck cancer  

PubMed Central

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

2010-01-01

193

Tip-enhanced near-field Raman spectroscopy applied to nano-composite materials  

NASA Astrophysics Data System (ADS)

Vibrational spectroscopy, including Raman spectroscopy can be used for identifying molecular species, which is not possible by a scanning probe microscopy or an electron microscopy. Moreover, vibrational spectra contain structural information, such as intermolecular interactions, molecular orientations, and symmetry distortions of each species. Therefore, Raman spectroscopy is a powerful tool for studying the chemical composition of matter. By employing Tip-enhanced Raman spectroscopy (TERS), we can perform Raman spectroscopy with nano-scale spatial resolution. Our approach relies on the enhanced filed near a laser irradiated metal tip which works as the Raman excitation source. We have investigated nano-composite materials by TERS. Near-field Raman spectra revealed the nano-scale properties of molecules encapsulated in single-wall carbon nanotubes (SWNT). The enhanced field act on encapsulated molecules through the wall of SWNT to extract chemical information inside. ?-carotene which has strong Raman intensities under visible light illuminations is used as an encapsulated molecule. The advantage of Raman spectroscopy is that the information of both SWNT and ?-carotene can be obtained at the same time. So, it is possible to discuss the interaction between SWNT and the encapsulated molecules. Near-field Raman spectra measured at several different positions on SWNT bundle show that ?-carotenes inside the tube are not uniformly distributed. We also find that the filling rates and the peak positions of the radial breathing mode of SWNT are linearly correlated.

Saito, Yuika; Yanagi, Kazuhiro; Hayazawa, Norihiko; Kataura, Hiromichi; Kawata, Satoshi

2007-10-01

194

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

2012-07-05

195

Amplifier/compressor fiber Raman lasers.  

PubMed

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

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

1987-10-01

196

The Impact of Array Detectors on Raman Spectroscopy  

ERIC Educational Resources Information Center

The impact of array detectors in the field of Raman spectroscopy and all low-light-level spectroscopic techniques is examined. The high sensitivity of array detectors has allowed Raman spectroscopy to be used to detect compounds at part per million concentrations and to perform Raman analyses at advantageous wavelengths.

Denson, Stephen C.; Pommier, Carolyn J. S.; Denton, M. Bonner

2007-01-01

197

The Impact of Array Detectors on Raman Spectroscopy  

ERIC Educational Resources Information Center

|The impact of array detectors in the field of Raman spectroscopy and all low-light-level spectroscopic techniques is examined. The high sensitivity of array detectors has allowed Raman spectroscopy to be used to detect compounds at part per million concentrations and to perform Raman analyses at advantageous wavelengths.|

Denson, Stephen C.; Pommier, Carolyn J. S.; Denton, M. Bonner

2007-01-01

198

Studies of growth, microstructure, Raman spectroscopy and annealing effect of pulsed laser deposited Ca-doped NBCO thin films  

Microsoft Academic Search

Superconducting thin films of Nd1?xCaxBa2Cu3O7?? (x = 0.03 and 0.08) have been grown on single crystal SrTiO3 substrates by pulsed laser deposition. The statistical methods of Experimental Design and regression analysis were used to optimize the film properties and to understand the correlation between the growth parameters and film properties. The orientation of the films was investigated by x-ray diffraction.

R Palai; E J Romans; R W Martin; F T Docherty; P Maas; C M Pegrum

2005-01-01

199

In vivo blood glucose quantification using Raman spectroscopy.  

PubMed

We here propose a novel Raman spectroscopy method that permits the noninvasive measurement of blood glucose concentration. To reduce the effects of the strong background signals produced by surrounding tissue and to obtain the fingerprint Raman lines formed by blood analytes, a laser was focused on the blood in vessels in the skin. The Raman spectra were collected transcutaneously. Characteristic peaks of glucose (1125 cm(-1)) and hemoglobin (1549 cm(-1)) were observed. Hemoglobin concentration served as an internal standard, and the ratio of the peaks that appeared at 1125 cm(-1) and 1549 cm(-1) peaks was used to calculate the concentration of blood glucose. We studied three mouse subjects whose blood glucose levels became elevated over a period of 2 hours using a glucose test assay. During the test, 25 Raman spectra were collected transcutaneously and glucose reference values were provided by a blood glucose meter. Results clearly showed the relationship between Raman intensity and concentration. The release curves were approximately linear with a correlation coefficient of 0.91. This noninvasive methodology may be useful for the study of blood glucose in vivo. PMID:23133555

Shao, Jingwei; Lin, Manman; Li, Yongqing; Li, Xue; Liu, Junxian; Liang, Jianpin; Yao, Huilu

2012-10-25

200

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

Microsoft Academic Search

The vital ultraviolet- (UV-) protective and photosynthetic pigments of cyanobacteria and lichens (microbial symbioses) that dominate primary production in Antarctic desert ecosystems auto-fluoresce at short wavelengths. We therefore use a long-wavelength (1064 nm) infrared laser for non-intrusive in situ Raman spectrometry of their ecologically significant compounds (especially pigments). To confirm that the power loss at this longer wavelength is justified

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

2002-01-01

201

Laser-induced synthesis of metallic silver-gold nanoparticles encapsulated in carbon nanospheres for surface-enhanced Raman spectroscopy and toxins detection  

NASA Astrophysics Data System (ADS)

Metallic silver-gold nanoparticles (1-5 nm) encapsulated into carbon nanospheres (20-30 nm) were synthesized via laser-induced chemical liquid phase deposition. The obtained carbon-silver-gold nanostructures were characterized by high specific surface area and demonstrated high sensitivity as a material for surface-enhanced Raman scattering and adsorption properties allowing analyte extraction from a dilute solution for quantitative monitoring of low concentration components.

Povolotskiy, Alexey; Povolotckaia, Anastasia; Petrov, Yuriy; Manshina, Alina; Tunik, Sergey

2013-09-01

202

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

203

Summary report of FY 1995 Raman spectroscopy technology development  

SciTech Connect

US DOE is sponsoring development of remote, fiber-optic Raman spectroscopy for rapid chemical characterization of Hanford high-level radioactive tank waste. Deployment targets for this technology are analytical hot cells and, via the Light-Duty Utility Arm and cone penetrometer, the waste tanks themselves. Perceived benefits of fiber-optic Raman spectroscopy are (1) rapid generation of tank-waste safety-related data, (2) reduced personnel exposure to highly radioactive waste, (3) reduced tank-waste sampling and analysis costs, and (4) reduced radioactive analytical waste. This document presents the results from the investigation of two dispersive, transmission-grating Raman systems and four fiber-optic Raman probe designs with non-radioactive tank waste simulants. One Raman system used a 532-nm, 400 mW, solid-state laser; the other used a 785-nm, 500 mW, solid-state diode laser. We found (1) the transmission-grating systems had better wavelength stability than previously tried Czerny-Turner-Based systems and (2) the 785-nm system`s specie detection limits in the spectral fingerprint regiion were at least as good as those for the 532-nm system. Based on these results, and the fact that some tank wastes luminesce with 514.5nm excitation, we selected the 785-nm system for hot-cell use. Of the four probes tested, three had a ``six-around-on`` fiber probe design; the fourth probe was a one-fiber-in-one-fiber-out, diffuse-relectance design. Comparison of the four probes` signal-to-noise rations, rations, transmission/collection efficiencies, and probe-silica Raman backgrounds showed that the best probe for use with Hanford-Site tank waste should (1) be filtered as close to the probe tip as possible to reduce the probe-silica Raman background and (2) have multiple collection fibers. The responses of all the probes tested showed a strong dependence on probe-sample distance, and the presence of a probe window appeared to increase the probe`s silica Raman background.

Douglas, J.G.

1995-11-01

204

Surface enhanced Raman spectroscopy in breast cancer cells  

PubMed Central

Background and aims: Raman spectroscopy is a vibrational technique which provides information about the chemical structure. Nevertheless, since many chemicals are present in a cell at very low concentration, the Raman signal observed from a single cell is extremely weak. In surface enhanced Raman scattering (SERS), Raman signals can be enhanced by many orders of magnitude when nanoparticles are incorporated into the cell. Materials (subjects) and methods: The tumor biopsies were obtained from 5 patients who were clinically diagnosed with breast cancer. Breast cancer cells isolated from the biopsy were washed, centrifuged and seeded out. Cultivation took place in DMEM at 37°C in a humidified of 5% CO2 in air with addition of colloidal silver nanoparticles of 40 nm into the cell by sonication. Immediately, the washed cells were analyzed in phosphate buffered saline (PBS) at pH 7. Raman analysis was carried out on the Jobin-Yvon LabRAM HR800 microscope system, with a NIR 830 nm laser excitation source. Results: The strongly enhanced Raman signals allow Raman measurements of a single cell in the 200–1800 cm?1 range in relatively short collection times (5 second) using 17 mW near-infrared excitation. Observed spectral features differed across the cell, but chemical constituents in the cell nucleus and cytoplasm, such as DNA, RNA, and amino acids tyrosine and phenylalanine can be identified. Conclusions: Particularly strong field enhancement can be observed when nanoparticles form colloidal clusters. The results suggest that SERS could be a new technique for the identification of breast cancer cell.

Gonzalez-Solis, JL; Luevano-Colmenero, GH; Vargas-Mancilla, J

2013-01-01

205

Raman spectroscopy of halotrichite from Jaroso, Spain  

Microsoft Academic Search

Raman spectroscopy complimented with infrared ATR spectroscopy has been used to characterise a halotrichite FeSO4·Al2(SO4)3·22H2O from The Jaroso Ravine, Aquilas, Spain. Halotrichites form a continuous solid solution series with pickingerite and chemical analysis shows that the jarosite contains 6% Mg2+. Halotrichite is characterised by four infrared bands at 3569.5, 3485.7, 3371.4 and 3239.0cm?1. Using Libowitsky type relationships, hydrogen bond distances

Ray L. Frost; Matt L. Weier; J. Theo Kloproggea; Fernando Rull; Jesus Martinez-Frias

2005-01-01

206

Fourier transform raman spectroscopy of synthetic and biological calcium phosphates  

Microsoft Academic Search

Fourier-transform (FT) Raman spectroscopy was used to characterize the organic and mineral components of biological and synthetic calcium phosphate minerals. Raman spectroscopy provides information on biological minerals that is complimentary to more widely used infrared methodologies as some infrared-inactive vibrational modes are Raman-active. The application of FT-Raman technology has, for the first time, enabled the problems of high sample fluorescence

G. R. Sauer; W. B. Zunic; J. R. Durig; R. E. Wuthier

1994-01-01

207

Near-infrared Raman spectroscopy of single optically trapped biological cells  

NASA Astrophysics Data System (ADS)

We report on the development and testing of a compact laser tweezers Raman spectroscopy (LTRS) system. The system combines optical trapping and near-infrared Raman spectroscopy for manipulation and identification of single biological cells in solution. A low-power diode laser at 785 nm was used for both trapping and excitation for Raman spectroscopy of the suspended microscopic particles. The design of the LTRS system provides high sensitivity and permits real-time spectroscopic measurements of the biological sample. The system was calibrated by use of polystyrene microbeads and tested on living blood cells and on both living and dead yeast cells. As expected, different images and Raman spectra were observed for the different cells. The LTRS system may provide a valuable tool for the study of fundamental cellular processes and the diagnosis of cellular disorders.

Xie, Changan; Dinno, Mumtaz A.; Li, Yong-Qing

2002-02-01

208

In situ raman spectroscopy studies of VPO catalyst transformations  

Microsoft Academic Search

VPO catalyst transformations were investigated using in situ laser Raman spectroscopy. During reduction-oxidation step changes, (VO)âPâOâ was readily converted to α{sub II}, δ-VOPOâ, and ultimately to β-VOPOâ in Oâ\\/Nâ; these V{sup 5+} phases were eliminated in n-butane\\/Nâ. A wet Nâ feed (5--10% HâO in Nâ) transformed (VO)âPâOâ and αâ-, α{sub II}-, β-, δ-, γ-VOPOâ to VâOâ at temperatures above 400

Z. Y. Xue; G. L. Schrader

1999-01-01

209

Raman spectroscopy of halotrichite from Jaroso, Spain.  

PubMed

Raman spectroscopy complimented with infrared ATR spectroscopy has been used to characterise a halotrichite FeSO(4) x Al(2)(SO(4))(3) x 22 H(2)O from The Jaroso Ravine, Aquilas, Spain. Halotrichites form a continuous solid solution series with pickingerite and chemical analysis shows that the jarosite contains 6% Mg(2+). Halotrichite is characterised by four infrared bands at 3569.5, 3485.7, 3371.4 and 3239.0 cm(-1). Using Libowitsky type relationships, hydrogen bond distances of 3.08, 2.876, 2.780 and 2.718 Angstrom were determined. Two intense Raman bands are observed at 987.7 and 984.4 cm(-1) and are assigned to the nu(1) symmetric stretching vibrations of the sulphate bonded to the Fe(2+) and the water units in the structure. Three sulphate bands are observed at 77K at 1000.0, 991.3 and 985.0 cm(-1) suggesting further differentiation of the sulphate units. Raman spectrum of the nu(2) and nu(4) region of halotrichite at 298 K shows two bands at 445.1 and 466.9 cm(-1), and 624.2 and 605.5 cm(-1), respectively, confirming the reduction of symmetry of the sulphate in halotrichite. PMID:16257711

Frost, Ray L; Weier, Matt L; Kloprogge, J Theo; Rull, Fernando; Martinez-Frias, Jesus

2005-01-26

210

Raman spectroscopy of halotrichite from Jaroso, Spain  

NASA Astrophysics Data System (ADS)

Raman spectroscopy complimented with infrared ATR spectroscopy has been used to characterise a halotrichite FeSO 4·Al 2(SO 4) 3·22H 2O from The Jaroso Ravine, Aquilas, Spain. Halotrichites form a continuous solid solution series with pickingerite and chemical analysis shows that the jarosite contains 6% Mg 2+. Halotrichite is characterised by four infrared bands at 3569.5, 3485.7, 3371.4 and 3239.0 cm -1. Using Libowitsky type relationships, hydrogen bond distances of 3.08, 2.876, 2.780 and 2.718 Å were determined. Two intense Raman bands are observed at 987.7 and 984.4 cm -1 and are assigned to the ?1 symmetric stretching vibrations of the sulphate bonded to the Fe 2+ and the water units in the structure. Three sulphate bands are observed at 77 K at 1000.0, 991.3 and 985.0 cm -1 suggesting further differentiation of the sulphate units. Raman spectrum of the ?2 and ?4 region of halotrichite at 298 K shows two bands at 445.1 and 466.9 cm -1, and 624.2 and 605.5 cm -1, respectively, confirming the reduction of symmetry of the sulphate in halotrichite.

Frost, Ray L.; Weier, Matt L.; Kloprogge, J. Theo; Rull, Fernando; Martinez-Frias, Jesus

2005-11-01

211

Raman forward scattering of chirped laser pulses  

Microsoft Academic Search

Raman scattering of a high-intensity, short-duration, frequency-chirped laser pulse propagating in an underdense plasma is examined. The growth of the direct forward scattered light is calculated for a laser pulse with a linear frequency chirp in various spatiotemporal regimes. This includes a previously undescribed regime of strongly coupled four-wave nonresonant interaction, which is important for relativistic laser intensities. In all

C. B. Schroeder; E. Esarey; B. A. Shadwick; W. P. Leemans

2003-01-01

212

Raman forward scattering of chirped laser pulses  

Microsoft Academic Search

Raman scattering of a high-intensity, short duration, frequency-chirped laser pulse propagating in an underdense plasma is examined. The growth of the direct forward scattered light is calculated for a laser pulse with a linear frequency chirp in various spatio-temporal regimes. This includes a previously undescribed regime of strongly-coupled four-wave nonresonant interaction, which is important for relativistic laser intensities. In all

C. B. Schroeder; E. Esarey; B. A. Shadwick; W. P. Leemans

2002-01-01

213

Chaotic behavior of a Raman ring laser  

NASA Astrophysics Data System (ADS)

The dynamical behavior of a Raman ring laser is examined under conditions of pump depletion. In the plane-wave and adiabatic limits, a mapping is obtained for two complex field amplitudes. Chaos is observed when injected pump and Stokes frequencies are detuned from a Raman resonance. Hyperchaos, characterized by two positive Liapunov exponents, is found when in addition the two injected fields are of comparable magnitudes.

Englund, John C.

1991-09-01

214

Average Power and Brightness Scaling of Diamond Raman Lasers.  

National Technical Information Service (NTIS)

Diamond holds substantial promise as a high Raman gain laser material with outstanding power handling capability, yet despite this the highest reported output power from a diamond Raman laser prior to this project was approximately 1 W. This report descri...

R. Mildren

2012-01-01

215

Optical trapping and Raman spectroscopy of single living cells: principle and applications  

NASA Astrophysics Data System (ADS)

This paper reports the principle and applications of the combination technique of optical trapping and Raman spectroscopy for real-time analysis of single living cells. We demonstrate that the information of each substance inside a captured cell can be retrieved by the Raman spectrum of the cell. The effect of alcohol solution on single human Red Blood Cell (RBC) is investigated using near-infrared laser tweezers Raman spectroscopy (LTRS). The significant difference between the spectrum of fresh RBC and the spectrum of RBC exposed to alcohol is observed due to the degradation of RBC. We also present the preliminary study result on the diagnosis of colorectal cancer using LTRS system.

Deng, Jianliao; Wei, Qing; Wang, Yuzhu; Li, Yong Qing

2005-01-01

216

Raman spectroscopy - in situ characterization of growth and surface processes  

NASA Astrophysics Data System (ADS)

The goal of this thesis is to expand on the usefulness of Raman spectroscopy as an in situ probe to aid in the growth and implementation of electronic, optical, and biodetection materials. We accomplish this goal by developing two diverse optical characterization projects. In the first project, an autoclave similar to those used in solvothermal growth which has been outfitted with an optical window is used to collect vibrational spectra of solvents and mineralizers commonly used in the ammonothermal growth of gallium nitride. Secondly, novel silver nanowires created by ferroelectric lithography are evaluated by surface enhanced micro-Raman spectroscopy for use as surface enhanced substrates for low detection limit or single molecule bio-detectors. Raman spectroscopy is already a widely accepted method to characterize and identify a wide variety of materials. Vibrational spectra can yield much information on the presence of chemical species as well as information regarding the phase and interactive properties. Because Raman spectroscopy is a generally non-intrusive technique it is ideal for analysis of hazardous or far-from-ambient liquids, gases, or solids. This technique is used in situ to characterize crystal growth and surface enhanced photochemistry. The phenomenon of Surface Enhanced Raman Spectroscopy (SERS) has been observed in many systems but some fundamental understanding is still lacking and the technique has been slow to transition from the laboratory to the industry. Aggregated colloids and lithographically created islands have shown the best success as reproducible substrates for SERS detection. These techniques, however, lack control over shape, size, and position of the metal nanoparticles which leave them reliant on hotspots. Because of the potential for control of the position of aggregates, ferroelectric lithographically created silver nanowires are evaluated as a potential SERS substrate using pyridine, benzoic acid, and Rhodamine 6g. Surface enhancement from these samples varies periodically as excitation light is scanned perpendicular to the wires. The periodicity, however, has the frequency of the positive domains where carbon laser damage is preferentially created. There is a current need for homoepitaxial substrates for gallium nitride devices including light emitting diodes, transistors, and laser diodes. Ammonothermal growth is a promising technique for creating bulk single crystalline GaN, but questions remain concerning the intermediates of reactions in supercritical Ammonia. Neat ammonia and water are monitored by Raman spectroscopy from room temperature to 500°C and 20 kpsi with both UV and visible excitation. In both systems, the amount of hydrogen bonding, which can be determined by O-H and N-H stretch frequency shifts, decreases with increasing temperature. In supercritical ammonia, the degree of Fermi resonance between the nu1 and 2nu4 modes decreases linearly with temperature while a minimum in pyramidal height of the NH3 molecule is reached at moderate pressures. Binary solutions of sodium azide and ammonia are investigated to temperatures which allow observation of the breakdown of the azides. The pressure and N2 Raman signal increase as the azide decomposes to sodium amide and N2 and H2 process gasses. The rate of decrease of the Raman signal of the azide increases as the reaction proceeds suggesting that the reaction rate is proportional to the pressure. The Fermi resonance, hydrogen bonding, and pyramidal height parameters were not affected by the presence of the azide.

Perkins, James Robert

217

Chemical analysis of acoustically levitated drops by Raman spectroscopy.  

PubMed

An experimental apparatus combining Raman spectroscopy with acoustic levitation, Raman acoustic levitation spectroscopy (RALS), is investigated in the field of physical and chemical analytics. Whereas acoustic levitation enables the contactless handling of microsized samples, Raman spectroscopy offers the advantage of a noninvasive method without complex sample preparation. After carrying out some systematic tests to probe the sensitivity of the technique to drop size, shape, and position, RALS has been successfully applied in monitoring sample dilution and preconcentration, evaporation, crystallization, an acid-base reaction, and analytes in a surface-enhanced Raman spectroscopy colloidal suspension. PMID:19418043

Tuckermann, Rudolf; Puskar, Ljiljana; Zavabeti, Mahta; Sekine, Ryo; McNaughton, Don

2009-05-06

218

Raman spectroscopy of small-diameter nanotubes  

NASA Astrophysics Data System (ADS)

Results based on Raman measurements of small-diameter nanotubes (NTs) are presented and discussed in this paper. The NTs with diameters from 1 nm down to 0.4 nm were produced either as the inner tubes in the double-wall carbon NTs (DWCNTs) or as tubes embedded in the channels of the zeolite crystals. While analysing the Raman spectra attention was paid to the radial breathing mode (RBM), the D line and the G band. For both NT systems the RBM frequency was found to follow the same functional diameter dependence as the tubes with larger diameters. However, in contrast to the latter, the diameters of the thin tubes obtained from density functional theory calculations must be taken into account to explain satisfactorily the observed line positions. The resonance behaviour of the RBM intensities was recorded for the tubes in zeolites. It allows us to ascribe a position of the RBM to a particular NT. This result also demonstrates the breakdown of a simple tight-binding approach to the electronic structure but agrees with predictions from ab initio calculations. The D line of the outer tubes in DWCNTs is dispersive, similar to the single-wall carbon NTs. However, the rate of dispersion is reduced for the inner tubes in DWCNTs. This is attributed to the fact that the inner and outer tubes are probed with the same laser excitation. The linear shift due to the increasing laser energy is compensated by the negative shift due to the NT diameter. The latter is smaller for the inner NTs which leads to a stronger compensation of their dispersive behaviour. This effect is even stronger for the NTs in zeolites. In the extreme case, the strong Raman lines are not dispersive at all. This unexpected behaviour was explained by the detailed ab initio calculation of the phonon structure. The G bands of the inner semiconducting tubes were observed as new features in the Raman spectra of DWCNTs. On the other hand, no lines of metallic inner tubes were found. G bands of semiconducting as well as metallic NTs were detected for the zeolite samples. In either case, Raman lines due to the recently proposed Peierls-like mechanism for the thin metallic tubes were not indentified. This mechanism must therefore cause a significant reduction in Raman intensity. EHPRG Award Lecture.

Hulman, M.; Pfeiffer, R.; Kuzmany, H.

2004-01-01

219

Test report for remote vs. contact Raman spectroscopy  

SciTech Connect

This report details the evaluation of two methods of spatially characterizing the chemical composition of tank core samples using Raman spectroscopy. One method involves a spatially-scanned fiber optic probe. The fiber optic probe must be in contact with a sample to interrogate its chemical composition. The second method utilizes a line-of-sight technique involving a remote imaging spectrometer that can perform characterization over an entire surface. Measurements using the imaging technique are done remotely, requiring no contact with the sample surface. The scope of this document studies the effects of laser power, distance from each type of probe to the sample surface, and interferences unique to the two methods. This report also documents the results of comparative studies of sensitivity to ferrocyanide, a key contaminant of concern in the underground storage tanks at DOE`s Hanford site. The effect of other factors on signal intensity such as moisture content is explored. The results from the two methods are compared, and a recommendation for a Raman hot cell core scanning system is presented based on the test results. This work is part of a joint effort involving several DOE laboratories for the design and development of Raman spectroscopy systems for tank waste characterization at Westinghouse Hanford Company under the auspices of the U.S. Department of Energy`s Underground Storage Tank Integrated Demonstration.

Kyle, K.R.

1994-05-01

220

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.

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

2011-01-01

221

In vivo lipidomics using single-cell Raman spectroscopy.  

PubMed

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

2011-02-10

222

Stand-off detection of chemicals by UV Raman spectroscopy  

SciTech Connect

Experimental results are reported on a mobile, stand-alone, solar-blind ultraviolet (UV) Raman lidar system for the stand-off detection and identification of liquid and solid targets at ranges of hundreds of meters. The lidar is a coaxial system capable of performing range-resolved measurements of gases and aerosols, as well as solids and liquids. The transmitter is a flash lamp pumped 30 Hz Nd:YAG laser with quadrupled output at 266 nm. The receiver subsystem is comprised of a 40 cm Cassegrain telescope, a holographic UV edge filter for suppressing the elastic channel, a 0.46 m Czerny-Turner spectrometer, and a time gated intensified charge-coupled device (CCD) detector. The rejection of elastic light scattering by the edge filter is better than one part in 10{sup 5}, while the transmittance 500 cm-1 to the red of the laser line is greater than 50%. Raman data are shown for selected solids, neat liquids, and mixtures down to the level of 1% volume ratio. On the basis of the strength of the Raman returns, a stand-off detection limit of {approx}500 g/m2 for liquid spills of common solvents at the range of one half of a kilometer is possible. (c) 2000 Society for Applied Spectroscopy.

Wu, Ming [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ray, Mark [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States); Hang Fung, K. [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States); Ruckman, Mark W. [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States); Harder, David [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States); Sedlacek, Arthur J. III [Department of Advanced Technology, Brookhaven National Laboratory, Upton, New York 11973 (United States)

2000-06-01

223

Evaluation of thyroid tissue by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Thyroid gland is a small gland in the neck consisting of two lobes connected by an isthmus. Thyroid's main function is to produce the hormones thyroxine (T4), triiodothyronine (T3) and calcitonin. Thyroid disorders can disturb the production of these hormones, which will affect numerous processes within the body such as: regulating metabolism and increasing utilization of cholesterol, fats, proteins, and carbohydrates. The gland itself can also be injured; for example, neoplasias, which have been considered the most important, causing damage of to the gland and are difficult to diagnose. There are several types of thyroid cancer: Papillary, Follicular, Medullary, and Anaplastic. The occurrence rate, in general is between 4 and 7%; which is on the increase (30%), probably due to new technology that is able to find small thyroid cancers that may not have been found previously. The most common method used for thyroid diagnoses are: anamnesis, ultrasonography, and laboratory exams (Fine Needle Aspiration Biopsy- FNAB). However, the sensitivity of those test are rather poor, with a high rate of false-negative results, therefore there is an urgent need to develop new diagnostic techniques. Raman spectroscopy has been presented as a valuable tool for cancer diagnosis in many different tissues. In this work, 27 fragments of the thyroid were collected from 18 patients, comprising the following histologic groups: goitre adjacent tissue, goitre nodular tissue, follicular adenoma, follicular carcinoma, and papillary carcinoma. Spectral collection was done with a commercial FTRaman Spectrometer (Bruker RFS100/S) using a 1064 nm laser excitation and Ge detector. Principal Component Analysis, Cluster Analysis, and Linear Discriminant Analysis with cross-validation were applied as spectral classification algorithm. Comparing the goitre adjacent tissue with the goitre nodular region, an index of 58.3% of correct classification was obtained. Between goitre (nodular region and adjacent tissue) and papillary carcinoma, the index of correct classification was 64.9%, and the classification between benign tissues (goitre and follicular adenoma) and malignant tissues (papillary and follicular carcinomas), the index was 72.5%.

Teixeira, C. S. B.; Bitar, R. A.; Santos, A. B. O.; Kulcsar, M. A. V.; Friguglietti, C. U. M.; Martinho, H. S.; da Costa, R. B.; Martin, A. A.

2010-02-01

224

Fifth-order nonresonant Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In this thesis, fifth-order nonresonant Raman spectroscopy is used to study the intermolecular motions of carbon disulfide so as to address fundamental questions about liquid dynamics. These questions, such as how diffusive dynamics (i.e. those involving structural change) emerge from fluctuations of individual molecules around their equilibrium positions, are directly addressed by fifth-order nonresonant Raman spectroscopy. This is due to the fifth-order signal's sensitivity to (and dependence upon) electrical or mechanical anharmonicity of the studied system, which is not a characteristic of lower-order spectroscopies. In this thesis, first it is shown that early attempts to measure the fifth-order nonresonant Raman signal of the low frequency motions of liquids were marred by the presence of lower-order cascading signals. These cascading signals do not depend on anharmonicity and thus do not contain the detailed molecular information that the fifth-order signal contains. It is shown that careful consideration of phase matching conditions allows one to suppress the lower-order cascading processes in favor of the desired fifth-order signal. In order to understand the measured fifth-order signals, both comparison to theory and signal processing is employed. An analysis of the full polarization dependence of the signal, based on early instantaneous normal mode analysis, is presented. A Fourier deconvolution of the measured signal is performed in order to isolate the portion of the fifth-order response most directly related to the details of liquid motion. Next, a heterodyne detection scheme, which allows for measurement of the sign and phase of the fifth-order nonresonant signal, is introduced. Heterodyne detected data from carbon disulfide is compared with simulations based on various theories. Most fruitfully, the data is compared with molecular dynamics simulations. Such comparison allows pinpointing the origin of key features of the measured signals.

Kaufman, Laura Jill

225

Spin-flip Raman laser at wavelengths up to 16.8 mum  

Microsoft Academic Search

An InSb spin-flip Raman (SFR) laser is pumped with an optically pumped NH3 laser line at 780.515 cm-1 to obtain tunable first Stokes laser radiation at wavelengths up to 16.8 mum. We report results on the power output, tunability, and preliminary spectroscopy of UF6. Scaling of the primary CO2 pump laser as well as the NH3 laser together with the

C. K. N. Patel; T. Y. Chang; V. T. Nguyen

1976-01-01

226

Spin-flip Raman laser at wavelengths up to 16.8 ?m  

Microsoft Academic Search

An InSb spin-flip Raman (SFR) laser is pumped with an optically pumped NH3 laser line at 780.515 cm?1 to obtain tunable first Stokes laser radiation at wavelengths up to 16.8 ?m. We report results on the power output, tunability, and preliminary spectroscopy of UF6. Scaling of the primary CO2 pump laser as well as the NH3 laser together with the

C. K. N. Patel; T. Y. Chang; V. T. Nguyen

1976-01-01

227

High-vacuum tip enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Tip-enhanced Raman spectroscopy (TERS) is high-sensitivity and high spatial-resolution optical analytical technique with nanoscale resolution beyond the diffraction limit. It is also one of the most recent advances in nanoscale chemical analysis. This review provides an overview of the state-of-art inTERS, in-depth information about the different available types of instruments including their (dis)advantages and capabilities. Finally, an overview about recent development in High-Vacuum TERS is given and some challenges are raised.

Zhang, Zheng-Long; Chen, Li; Sheng, Shao-Xiang; Sun, Meng-Tao; Zheng, Hai-Rong; Chen, Ke-Qiu; Xu, Hong-Xing

2013-08-01

228

Raman Spectroscopy: A Suitable Tool For Planetary Investigations  

Microsoft Academic Search

For a fundamental understanding of the origin and evolution of planets information on the surface material is required. Raman spectroscopy represents one possible method for performing mineralogical studies. Raman imaging, delivers information about the identity and the spatial distribution of the various components of the sample. One way of performing this type of measurements is to bring a Raman device

J. Popp; N. Tarcea; M. Schmitt; W. Kiefer; R. Hochleitner; G. Simon; S. Hofer; E. Schmidt; T. Stuffler; M. Hilchenbach

2002-01-01

229

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

230

Hyperspectral imaging with stimulated Raman scattering by chirped femtosecond lasers.  

PubMed

Raman microscopy is a quantitative, label-free, and noninvasive optical imaging technique for studying inhomogeneous systems. However, the feebleness of Raman scattering significantly limits the use of Raman microscopy to low time resolutions and primarily static samples. Recent developments in narrowband stimulated Raman scattering (SRS) microscopy have significantly increased the acquisition speed of Raman based label-free imaging by a few orders of magnitude, at the expense of reduced spectroscopic information. On the basis of a spectral focusing approach, we present a fast SRS hyperspectral imaging system using chirped femtosecond lasers to achieve rapid Raman spectra acquisition while retaining the full speed and image quality of narrowband SRS imaging. We demonstrate that quantitative concentration determination of cholesterol in the presence of interfering chemical species can be achieved with sensitivity down to 4 mM. For imaging purposes, hyperspectral imaging data in the C-H stretching region is obtained within a minute. We show that mammalian cell SRS hyperspectral imaging reveals the spatially inhomogeneous distribution of saturated lipids, unsaturated lipids, cholesterol, and protein. The combination of fast spectroscopy and label-free chemical imaging will enable new applications in studying biological systems and material systems. PMID:23256635

Fu, Dan; Holtom, Gary; Freudiger, Christian; Zhang, Xu; Xie, Xiaoliang Sunney

2013-01-18

231

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

232

Detection of Cervical Cancer Analyzing Blood Samples with Raman Spectroscopy and Multivariate Analysis  

NASA Astrophysics Data System (ADS)

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 20 patients who were clinically diagnosed with cervical cancer and 10 healthy volunteer. The imprint was put under the Olympus microscope and several points were chosen for Raman measurement. All spectra were collected at a Jobin-Yvon LabRAM HR800 Raman Spectrometer with NIR 830 nm laser. It is shown that the serum samples from patients with cervical cancer 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. The preliminary results suggest that Raman spectroscopy could be a new technique for the detection using just blood samples.

González-Solís, J. L.; Rodríguez-López, J.; Martínez-Espinosa, J. C.; Frausto-Reyes, C.; Jave-Suárez, L. F.; Aguilar-Lemarroy, A. C.; Vargas-Rodríguez, H.; Martínez-Cano, E.

2010-05-01

233

Stage Determination of Breast Cancer Biopsy Using Raman Spectroscopy and Multivariate Analysis  

NASA Astrophysics Data System (ADS)

The use of Raman spectroscopy to analyze biopsy biochemistry and hence distinguish between the breast cancer stages was investigated. The biopsy samples were obtained from 13 patients who were clinically diagnosed with breast cancer. A preliminary diagnosis of some breast cancer patient was realized by pathologist of the Cancer Institute. The biopsies were put under the microscope and several points were chosen for Raman measurement. All spectra were collected at a Jobin-Yvon LabRAM HR800 Raman Spectrometer with a NIR 830 nm laser. It is shown that the breast cancer stages of biopsies can be discriminated when the Principal Components Analysis (PCA) is applied to their Raman spectra. Ratios of some band intensities were analyzed and corresponded to proteins, phospholipids, and polysaccharides. The preliminary results suggest that Raman spectroscopy could be an excellent technique for stage determination of breast cancer.

González-Solís, J. L.; Aguiñaga-Serrano, B. I.; Martínez-Espinosa, J. C.; Oceguera-Villanueva, A.

2011-08-01

234

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

235

Disease recognition by infrared and Raman spectroscopy.  

PubMed

Infrared (IR) and Raman spectroscopy are emerging biophotonic tools to recognize various diseases. The current review gives an overview of the experimental techniques, data-classification algorithms and applications to assess soft tissues, hard tissues and body fluids. The methodology section presents the principles to combine vibrational spectroscopy with microscopy, lateral information and fiber-optic probes. A crucial step is the classification of spectral data by a variety of algorithms. We discuss unsupervised algorithms such as cluster analysis or principal component analysis and supervised algorithms such as linear discriminant analysis, soft independent modeling of class analogies, artificial neural networks support vector machines, Bayesian classification, partial least-squares regression and ensemble methods. The selected topics include tumors of epithelial tissue, brain tumors, prion diseases, bone diseases, atherosclerosis, kidney stones and gallstones, skin tumors, diabetes and osteoarthritis. PMID:19343682

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

2009-02-01

236

In-line interferometric femtosecond stimulated Raman scattering spectroscopy  

NASA Astrophysics Data System (ADS)

We present in-line interferometric femtosecond stimulated Raman scattering (II-FSRS), a new method to measure the spectral Raman intensity and phase over a broad spectral range, potentially in a single shot. An analytic model is developed, that excellently reproduces the measured spectra. Additionally, the performance of II-FSRS is directly compared in experiments to two established techniques, namely femtosecond stimulated Raman scattering and femtosecond Raman induced Kerr-effect spectroscopy.

Dobner, Sven; Groß, Petra; Fallnich, Carsten

2013-06-01

237

Application of an optical pulse stretcher to coherent anti-Stokes Raman spectroscopy.  

PubMed

An external optical cavity pulse stretcher for nanosecond-long laser pulses has been applied to coherent anti-Stokes Raman spectroscopy (CARS). An increased signal-to-noise ratio was achieved for both vibrational and pure rotational CARS, while the power density of the laser beams remained constant. Moreover, it was demonstrated that the use of the pulse stretcher also leads to improved precision of the determined temperatures and concentrations as a result of repeated excitation of the dye laser. PMID:15532274

Beyrau, Frank; Weikl, Markus Christian; Seeger, Thomas; Leipertz, Alfred

2004-10-15

238

Importance of substrate and photo-induced effects in Raman spectroscopy of single functional erythrocytes.  

PubMed

Hemoglobin (Hb) in single erythrocytes (red blood cells), adsorbed on polylysine-coated glass surfaces, was studied using resonance Raman spectroscopy and global Raman imaging. The erythrocytes were found to be sensitive to both surface adsorption and laser illumination. Substrate-dependent changes of the cell membrane shape were observed immediately after cell adsorption, while a photo-induced increase of fluorescence was observed for visible excitation (lambda=514.5 nm). Concurrent changes in Raman spectra revealed a conversion of oxy-Hb (2+) to the inactive met-Hb state (3+). These effects severely complicate the interpretation of Raman images. However, at a low accumulated photon dose, the preparation method enabled the recording of Raman spectra during the oxygenation cycle of a single erythrocyte in buffer, which illustrates the feasibility of Raman investigations of functional cells in in-vivo environments. PMID:12683842

Ramser, Kerstin; Bjerneld, Erik J; Fant, Camilla; Käll, Mikael

2003-04-01

239

Raman spectroscopy of single-domain multiferroic BiFeO3  

Microsoft Academic Search

We report the investigation of polarized Raman spectroscopy of multiferroic bismuth ferrite (BiFeO3) from 81-273 K, using a ferroelectric\\/ferroelastic single-domain crystal with an as-grown pseudocubic (pc) (100)pc -oriented surface, compared with (001)pc thin film, grown by pulsed laser deposition. The polarized Raman spectra of the single crystal taken at different crystallographic orientations agree with the rhombohedral crystal structure with C3v

R. Palai; H. Schmid; J. F. Scott; R. S. Katiyar

2010-01-01

240

Development of a compact high-resolution spectrometer for multi-line UV Raman spectroscopy  

Microsoft Academic Search

We report on the development of a compact and robust instrument for multi-line ultraviolet resonant Raman spectroscopy. This instrument will be able to collect simultaneous full-range (800-4000 cm-1) high-resolution Raman spectra resulting from resonance-enhanced excitation at multiple UV laser wavelengths. The resulting matrix of spectra will allow the identification and analysis of several organic chemical compounds of interest for the

James M. Kohel; James P. Kirby; James L. Lambert

2010-01-01

241

Raman Spectroscopy and EXAFS Studies of Low-Nickel Yttrium-Based Copper Oxide Polycrystalline Superconductors  

Microsoft Academic Search

Raman spectroscopy and EXAFS studies were conducted on YBa2Cu3O(7-d) samples doped with molar-proportional percentages (0.32replacing the Cu (Copper) in the starting materials, along with a control sample of pure YBCO. The Raman spectra were collected at 20 K using 150mW, 5145 Å laser excitation at the sample surface, along with an automated single grating (1200 grooves\\/mm) Triax 550 spectrometer equipped

Michael C. Baxa; No Soung Myoung; Laurie A. Pichla; Mark S. Boley

2002-01-01

242

Raman and Infrared Spectroscopy of Aqueous Corrosion Films on Lead.  

National Technical Information Service (NTIS)

The use of Raman and infrared spectroscopy to analyze surface films on metals is described. Surface films formed on lead by reaction with aqueous buffer solutions were examined. The composition of each film was determined by Raman spectroscopy while the s...

R. H. Heidersbach C. W. Brown R. J. Thibeau A. Z. Goldfarb

1978-01-01

243

Raman spectroscopy for the characterization of algal cells  

Microsoft Academic Search

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

Ota Samek; Alexandr Jonás; Zdenek Pilát; Pavel Zemánek; Ladislav Nedbal; Jan Tríska; Petr Kotas; Martin Trtílek

2010-01-01

244

Atom laser based on Raman transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state is pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to another cavity for the atomic ground state. Above a certain threshold pumping rate a large

G. M. Moy; J. J. Hope; C. M. Savage

1997-01-01

245

An Atom Laser Based on Raman Transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state $|1 >$ are pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to a single mode of another cavity for the ground atomic state, $|2 >$.

G. M. Moy; J. J. Hope; C. M. Savage

1996-01-01

246

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

247

Mode competition in Raman free electron lasers  

Microsoft Academic Search

A relativistic electromagnetic particle code with conducting boundary conditions in the transverse direction has been developed to investigate mode competition in Raman free electron lasers. The model allows three-dimensional spatial motion for electrons, as well as transverse inhomogeneity of the wiggler magnetic fields and is capable of including a finite number of various relevant TEmn modes. The code also contains

A. T. Lin; Chih-Chien Lin

1986-01-01

248

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

249

Laser ionization mass spectroscopy  

NASA Astrophysics Data System (ADS)

Laser Ionization Mass Spectroscopy (LIMS) is a simple technique with several advantages and disadvantages over standard mass spectroscopy techniques. The LIMS technique uses a laser to vaporize a small portion of a sample. The vapor from the sample consists of a mixture of charged and neutral atoms or fragments. Using electrostatic grids, the ions (positive or negative) are given a known amount of kinetic energy and sent down a time-of-flight tube. The time it takes the ions to travel down the flight tube is recorded. Knowing the ions' energy, the length of the flight tube, and the time it takes the ions to travel that distance, the masses of the ions can be calculated. The instrument used is a LIMA 3 made by Cambridge Mass Spectrometry. It has a Quanta Ray DCR-11 Nd:YAG laser, which was frequency-quadrupled to 266 nm. The laser spot size is typically between 2 and 5 microns in diameter and the pulse width is between 5 and 10 nanoseconds. The energy of the laser is continually variable between 0.1 and 3.0 millijoules. The detector is a 17-stage venetian-blind multiplier made by Thorn EMI. The analysis is carried out under vacuum, usually between 10(exp -8) and 10(exp -9) Torr. The LIMA 3 has several useful features such as: a He-Ne pilot laser used to target the Nd:YAG laser; a microscope (which is used to view the sample through the laser optics); and a precision sample stage for accurate sample alignment.

Bernardez, Luis J., III; Siekhaus, W. J.

1989-10-01

250

Laser Raman spectroscopy study of the zinc and bromide ion complex equilibrium in zinc/bromine battery electrolytes. [2M ZnBr/sub 2/ and 1M KBr solution  

SciTech Connect

Laser Raman spectroscopy was used to study the zinc and bromide ion complex equilibrium in zinc bromine battery model electrolytes. Solutions of zinc bromide with added KBr, HBr and N-methyl, N-ethyl morpholinium (MEM) bromide were examined and compared. Solutions studied ranged from 1 to 3 molar in zinc and from 2.5 to 8 molar in bromide. A typical Raman spectrum of a zinc bromide solution is shown in Figure 1. Each of the zinc species is identified, Zn/sup + +/ (aq), ZnBr/sup +/, ZnBr/sub 2/ (aq), ZnBr/sub 3//sup -/ and ZnBr/sub 4//sup 2 -/. By the use of peak heights or deconvolution/integration along with published Raman cross sections, the amount of each zinc species could be quantitatively determined. The addition of bromide ions to the zinc bromide solutions will shift the equilibrium toward higher bromide complexes. The added cations will influence the shifts. It has been noted that the conductivity of the electrolyte decreases when the quaternary ammonium ions are present compared to cations such as potassium or hydrogen. Significantly more free zinc is present in zinc bromide solutions with added KBr than with either MEMBr or HBr. Shifts are also noted with the other zinc ion containing species. It appears that the quaternary ammonium ions and possibly the pH could have a stabilizing effect on zinc bromide complex ion formation. 2 figs.

Grimes, P.G.; Larrabee, J.A.

1985-01-01

251

Two-dimensional-Raman-terahertz spectroscopy of water: Theory  

NASA Astrophysics Data System (ADS)

We discuss the hybrid 2D-Raman-THz spectroscopy of liquid water. This two-dimensional spectroscopy is designed to directly work in the low-frequency range of the intermolecular degrees of freedom. The information content of 2D-Raman-THz spectroscopy is similar to 2D-Raman or 2D-THz spectroscopy, but its experimental implementation should be easier. That is, 2D-Raman-THz spectroscopy is a 3rd-order nonlinear spectroscopy and as such completely avoids cascading of consecutive 3rd-order signals, which turned out to be a major difficulty in 5th-order 2D-Raman spectroscopy. On the other hand, it does not require any intense THz pump-pulse, the lack of which limits 2D-THz spectroscopy to the study of semiconductor quantum wells as the currently available pulse energies are too low for molecular systems. In close analogy to 2D-Raman spectroscopy, the 2D-Raman-THz response of liquid water is simulated from an all-atom molecular dynamics simulation, and the expected spectral features are discussed.

Hamm, Peter; Savolainen, Janne

2012-03-01

252

DNA-drug interaction. The effects of vitamin C on the solution structure of Calf-thymus DNA studied by FTIR and laser Raman difference spectroscopy.  

PubMed

The interaction of calf-thymus DNA with L-ascorbic acid was investigated in aqueous solution at pH=7.6 with drug/DNA(P)(P=phosphate) molar ratios (r) of 1/40, 1/20, 1/10, 1/5, 1/2, 1 and 2. Fourier Transform infrared (FTIR) and laser Raman difference spectroscopic techniques were used to establish correlations between spectral modifications and drug binding mode, sequence specificity, DNA melting and conformational changes, as well as structural variations of drug-DNA complexes in aqueous solution. Infrared and Raman spectroscopic results showed that at low drug concentration (r = 1/40), a B to A-type conformational conversion occurs with minor drug-DNA interaction through A-T bases. At r=1/20, drug-PO2 binding was also observed with reduced intensity of DNA inplane vibrational frequencies, due to the increased base-stacking interaction and duplex stability. At r> 1/20, major perturbations of DNA bases were observed for both A-T and G-C base pairs in the major and minor grooves of the duplex. Evidence for this comes form the shift of the infrared and Raman vibrations of the A-T and G-C bases on drug interaction. At r>1/5, a minor helix destabilization occurred with participation of several DNA donor sites in drug complexation. The ascorbate anion interaction occurred mainly through H-bonding of the acid OH and C-O groups with DNA phosphate, bases and doxyribose donor atoms. PMID:8579795

Neault, J F; Naoui, M; Tajmir-Riahi, H A

1995-10-01

253

Direct, non-destructive quantitative measurement of an active pharmaceutical ingredient in an intact capsule formulation using Raman spectroscopy  

Microsoft Academic Search

The active pharmaceutical ingredient (ambroxol) in an intact capsule formulation has been non-destructively quantified using Raman spectroscopy. To improve the problem of insufficient representive sampling inherent in Raman measurements, we have employed a wide area illumination (WAI) scheme that enables much improved sample coverage through a circular excitation laser spot with a 6mm diameter. One of the anticipated sources of

Jaejin Kim; Jaegeun Noh; Hoeil Chung; Young-Ah Woo; Mark S. Kemper; Youngil Lee

2007-01-01

254

Frequency doubling of a Raman fiber laser  

NASA Astrophysics Data System (ADS)

655 nm laser radiation with power of >60 mW is generated by frequency doubling of a broadband randomly-polarized 1.31-?m phosphosilicate Raman fiber laser (RFL). The red power appears to grow linearly with increasing RFL power up to 7 W at efficiency comparable with that for single-frequency lasers. It has been shown that multiple sum-frequency mixing processes involving different RFL modes provide the main contribution to the output, which is enhanced by 2 times due to the modes stochasticity.

Kablukov, S. I.; Babin, S. A.; Churkin, D. V.; Denisov, A. V.; Kharenko, D. S.

2010-02-01

255

Hydration of lysozyme studied by Raman spectroscopy.  

PubMed

Hydration plays a fundamental role in maintaining the three-dimensional structure and function of proteins. In this study, Raman spectroscopy was used to probe the hydration induced structural changes at various sites of lysozyme under isothermal conditions in the range of water contents from 0 to 44 wt %. Raman hydration curves were constructed from detailed analysis of marker bands. Transition inflection points (w(m)) and onsets determined from the hydration curves have shown that structural changes start at 7-10 and end at about 35 wt % water. The onset of structural changes coincides with the onset of the broad glass transition earlier observed in this system. The increase of ?-helix content starts at very low concentrations of water with w(m) = 12 wt %. Monitoring the development of importance for enzymatic action hydrophobic clusters has revealed wm = 15 wt % and completion of the process at 25 wt %. The parameters of 621 cm(-1) (Phe) and 1448 cm(-1) (CH2 bending) modes were found to be sensitive to hydration, suggesting changes in organization of water molecules near the protein surface. The native structure of lysozyme was achieved at 35 wt % water where its content is high enough for filling the space between lysozyme molecules. PMID:23557185

Kocherbitov, Vitaly; Latynis, Jekaterina; Misiunas, Audrius; Barauskas, Justas; Niaura, Gediminas

2013-04-22

256

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, Jr. , E. D.

1997-01-01

257

Discrimination of normal and colorectal cancer using Raman spectroscopy and fluorescence  

NASA Astrophysics Data System (ADS)

Laser-induced fluorescence spectroscopy (LIF) and Raman spectrum of serum for diagnosis of colon cancer and rectum cancer were investigated in this paper. The aim of this study was that using Raman spectrum and LIF analysis the serum of colon cancer and rectum cancer for found the difference compared to normal, the difference was found. For example: the intensity and red shift both different In this paper we investigated 82 colon cancers, 69 rectum cancers and obtained 80.7%, 82.5% accuracy to rectum cancer and colon cancer separately compared to clinical diagnostic. It is exploring that use Raman spectrum and LIF to detection of cancer.

Li, Xiaozhou; Wang, Deli; Wang, Yue

2007-06-01

258

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

259

Raman spectroscopy of hypersonic shock waves  

PubMed

Raman spectroscopy is shown to be an efficient diagnostic methodology for the study of hypersonic shock waves. As a test, absolute density and rotational population profiles have been measured across five representative normal shock waves of N2 generated in a free jet, spanning the Mach number range 7.7

Ramos; Mate; Tejeda; Fernandez; Montero

2000-10-01

260

Femtosecond Coherent Raman Spectroscopy in Biomolecules  

NASA Astrophysics Data System (ADS)

We present a scheme for identification of biomolecules in real time by using Coherent Anti-Stokes Raman Spectroscopy (CARS) with femtosecond pulses. The nonlinear interaction of the pulses with the molecules is calculated analytically as well as numerically and comparison is made with the experimental results. We show that the commonly used rotating wave approximation needs to be waved for our fast dephasing molecules. Propagation effects are simulated, in addition to the nonlinear interaction, and it is shown how one needs to balance the electronic resonance enhancement and the losses due to absorption, in order to maximize the signal at the output of the optically dense medium. In the transient regime, we present and analyze the generation of polarization beats. These beats are generated due to the very broad bandwidth of the femtosecond pulses, which allows for the coupling of more that one vibrational modes at a time.

Sariyanni, Zoe-Elizabeth; Rostovtsev, Yuri; Siebert, Torsten; Kiefer, Wolfgang; Beadie, Guy; Reintjes, John; Scully, Marlan

2006-03-01

261

Detection of early dental caries using polarized Raman spectroscopy  

NASA Astrophysics Data System (ADS)

A new technique based on polarized Raman spectroscopy is demonstrated for detecting early dental caries on extracted human teeth. Sound tooth enamel exhibited strong Raman polarization anisotropy whereas early caries consistently showed a lower degree of Raman polarization anisotropy. In particular, for sound enamel, the Raman peak arising from the symmetric ?1 vibration of PO4 3- at 959 cm-1 is strongly polarized. This is in contrast to the spectra of carious lesions that displayed weaker polarization dependence at 959 cm-1. Such difference in the degree of Raman polarization anisotropy allows for discrimination between early dental caries and sound enamel.

Ko, Alex C.-T.; Choo-Smith, Lin-P'ing; Hewko, Mark; Sowa, Michael G.; Dong, Cecilia C. S.; Cleghorn, Blaine

2006-01-01

262

Detection of early dental caries using polarized Raman spectroscopy.  

PubMed

A new technique based on polarized Raman spectroscopy is demonstrated for detecting early dental caries on extracted human teeth. Sound tooth enamel exhibited strong Raman polarization anisotropy whereas early caries consistently showed a lower degree of Raman polarization anisotropy. In particular, for sound enamel, the Raman peak arising from the symmetric nu1 vibration of PO(4) (3-) at 959 cm(-1) is strongly polarized. This is in contrast to the spectra of carious lesions that displayed weaker polarization dependence at 959 cm(-1). Such difference in the degree of Raman polarization anisotropy allows for discrimination between early dental caries and sound enamel. PMID:19503331

Ko, Alex C-T; Choo-Smith, Lin-P'ing; Hewko, Mark; Sowa, Michael G; Dong, Cecilia C S; Cleghorn, Blaine

2006-01-01

263

Coherent anti-stokes Raman spectroscopy system for point temperature and major species concentration measurement  

SciTech Connect

The Coherent anti-Stokes Raman Spectroscopy system (CARS) has been developed as a laser-based, advanced, combustion-diagnostic technique to measure temperature and major species concentration. Principles of operation, description of the system and its capabilities, and operational details of this instrument are presented in this report.

Singh, J.P.; Yueh, Fang-Yu

1993-10-01

264

Combined In Vivo Confocal Raman Spectroscopy and Confocal Microscopy of Human Skin  

Microsoft Academic Search

In vivo confocal Raman spectroscopy is a noninvasive optical method to obtain detailed information about the molecular composition of the skin with high spatial resolution. In vivo confocal scanning laser microscopy is an imaging modality that provides optical sections of the skin without physically dissecting the tissue. A combination of both techniques in a single instrument is described. This combination

P. J. Caspers; G. W. Lucassen; G. J. Puppels

2003-01-01

265

Brillouin and Raman scattering spectroscopy of the liquid-glass transition  

Microsoft Academic Search

The liquid-glass transition in calcium potassium nitrage (CKN), salol, and aqueous LiCl solution was investigated by laser light scattering spectroscopy. Combining data obtained with a Sandercock tandem Fabry Perot interferometer and a Spex tandem Raman spectrometer provided spectra spanning more than four decades in frequency. The data was analyzed to test both qualitative and quantitative predictions of the mode coupling

H. Z. Cummins; G. Li; W. M. Du; X. K. Chen; N. J. Tao; A. Sakai

1992-01-01

266

Diamond Raman laser in eye safe region  

NASA Astrophysics Data System (ADS)

The goal of this work was the external cavity CVD diamond Raman laser generating at wavelength of 1.63 ?m which belongs to an eye safe region. As the Raman medium a sample of CVD grown single diamond crystal was used. The crystal was grown in the [100] direction and after cutting, the sample sides were formed by {110} planes. The diamond crystal sample dimensions were 5 mm × 5 mm × 2 mm and it had no anti-reflection coatings. As a pumping radiation source the compact Q-switched Nd:YAP laser operating at the wavelength 1.34 ?m was used. The pulse duration was 12 ns. This pumping radiation was focused by the lens (f = 250 mm) perpendicularly on the diamond crystal face. The beam radius inside the crystal was 180 ?m. The 15 mm long Raman laser resonator was formed by a pumping mirror (HR @ 1.63 ?m and T = 97 % @ 1.34 ?m) and an output coupler (R = 95 % @ 1.63 ?m, r = 500 mm). The maximum generated laser output energy was 18 ?J @ 1.63 ?m for the pumping energy of 3.35 mJ corresponding to the conversion efficiency of 0.5 %. The output spatial beam profile corresponds to the fundamental Gaussian beam in both axes.

Jelinková, Helena; Kitzler, Ond?ej; Jelínek, Michal; Šulc, Jan; N?mec, Michal; Kube?ek, Václav

2011-09-01

267

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, Antônio L.; Duarte, Janaína; Martins, Maria C.

2003-06-01

268

Polymer-capped fiber-optic Raman probe for in-vivo non-invasive Raman tomography and spectroscopy  

NASA Astrophysics Data System (ADS)

As advances in fiber optic probe design move Raman spectroscopy into the clinic, there remain important practical problems. Most in-vivo non-invasive applications employ specialized fiber optic probes. Much effort has been devoted to minimizing Raman and fluorescence background from fiber. Less attention has been paid to the need to generate reference Raman signals proportional to delivered laser power without direct measurement of tissue albedo. Knowledge of laser power is needed for quantification of changes in tissue composition. The need is especially acute in diffuse Raman tomography, where accurate modeling of light transport through the tissue is required for accurate reconstruction of subsurface features. We describe a fiber optic probe that incorporates a transparent polymer cap at the end of each excitation fiber. As laser light propagates through the cap it generates Raman bands whose intensity can directly measure power delivered to the tissue of interest. Our first implementation uses a fluorinated ethylene-propylene copolymer (FEP) cap that is attached to the ferrule at the distal (delivery) end of each excitation fiber. FEP is transparent and functions as a waveguide with only a small insertion loss, about 5%. Importantly, there are few overlaps between the Raman bands of FEP and the bands of tissue constituents. The cap increases the diameter of the structure in contact with the specimen, but with extensive photon diffusion this makes little difference in performance. We present here latest non-invasive bone spectroscopy results with the calibrator. In addition, extensive enhancement of the calibration signal using a fluorocarbon optical fiber is discussed.

Okagbare, Paul I.; Morris, Michael D.

2012-02-01

269

Forensic and homeland security applications of modern portable Raman spectroscopy.  

PubMed

Modern detection and identification of chemical and biological hazards within the forensic and homeland security contexts may well require conducting the analysis in field while adapting a non-contact approach to the hazard. Technological achievements on both surface and resonance enhancement Raman scattering re-developed Raman spectroscopy to become the most adaptable spectroscopy technique for stand-off and non-contact analysis of hazards. On the other hand, spatially offset Raman spectroscopy proved to be very valuable for non-invasive chemical analysis of hazards concealed within non-transparent containers and packaging. PMID:20395087

Izake, Emad L

2010-04-14

270

Configurable three-wavelength Raman fiber laser for Raman amplification and dynamic gain flattening  

Microsoft Academic Search

A three-wavelength Raman fiber laser is presented that is suitable for the generation of a flattened Raman gain curve over a broad range of extended telecommunications bandwidths. This laser utilizes an 1100-nm Yb-doped cladding pumped fiber laser and a cascaded Raman resonator to generate output radiation at 1427, 1454, and 1480 nm. The slope efficiency for conversion from the 1100-

M. D. Mermelstein; C. Headley; J.-C. Bouteiller; P. Steinvurzel; C. Horn; K. Feder; B. J. Eggleton

2001-01-01

271

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

272

Temperature Dependent Ultraviolet Raman Spectroscopy of Monolayer Graphene Films  

NASA Astrophysics Data System (ADS)

Strong interest in Raman spectroscopy lies in that it delivers a wealth of information about the structure of graphene. Raman spectroscopy allows for the identification of graphene layers and disorder. We have produced monolayer graphene films with lateral dimensions on the order of centimeters on copper foils by chemical vapor deposition (CVD). Temperature dependent Raman spectra were obtained at multiple wavelengths including ultraviolet and visible and at temperatures from 10 K to 300 K. Here we present the effect of excitation wavelength and temperature on the Raman spectrum of CVD grown graphene and compare it to theoretical predictions. The changes in Raman linewidth and positions provide powerful information about anharmonicity and electron-phonon interactions. The obtained results are important for Raman nanometrology of graphene.

Calizo, Irene; Sperling, Brent; Giltinan, Joshua; Maslar, James; Hight Walker, Angela R.

2010-03-01

273

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

274

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

2008-11-05

275

Spectral broadening in Raman fiber lasers  

NASA Astrophysics Data System (ADS)

We present an analytical theory based on wave kinetic equations that describes a Raman fiber laser (RFL) generation spectrum. It is shown both theoretically and experimentally that the quasi-degenerate four-wave mixing between different longitudinal modes is the main broadening mechanism in the one-stage RFL at high powers. The shape and power dependence of the intracavity Stokes wave spectrum are in excellent quantitative agreement with predictions of the theory.

Babin, S. A.; Churkin, D. V.; Ismagulov, A. E.; Kablukov, S. I.; Podivilov, E. V.

2006-10-01

276

Spectral broadening in Raman fiber lasers.  

PubMed

We present an analytical theory based on wave kinetic equations that describes a Raman fiber laser (RFL) generation spectrum. It is shown both theoretically and experimentally that the quasi-degenerate four-wave mixing between different longitudinal modes is the main broadening mechanism in the one-stage RFL at high powers. The shape and power dependence of the intracavity Stokes wave spectrum are in excellent quantitative agreement with predictions of the theory. PMID:17001382

Babin, S A; Churkin, D V; Ismagulov, A E; Kablukov, S I; Podivilov, E V

2006-10-15

277

Atom laser based on Raman transitions  

Microsoft Academic Search

In this paper we present an atom laser scheme using a Raman transition for\\u000athe output coupling of atoms. A beam of thermal atoms (bosons) in a metastable\\u000aatomic state $|1 >$ are pumped into a multimode atomic cavity. This\\u000acavity is coupled through spontaneous emission to a single mode of another\\u000acavity for the ground atomic state, $|2 >$.

G. M. Moy; J. J. Hope; C. M. Savage

1997-01-01

278

Raman spectroscopy of gold nanoparticles in polycrystalline LiF film  

NASA Astrophysics Data System (ADS)

Results of the Raman spectroscopy analysis of a new composite material based on a thin polycrystalline LiF film containing gold nanoparticles are presented. The formation of spherical gold nanoparticles in the film has been confirmed by the X-ray structural analysis and observation of the optical plasmon resonance absorption spectrum with a maximum at 534 nm. The obtained composite layers have been subjected to annealing by ruby laser (? = 694 nm) in the spectral region on a descending long-wavelength wing of the plasmon absorption band of gold nanoparticles. Raman spectroscopy has been applied for the first time to the investigation of the modification of the shape of gold nanoparticles in LiF during laser annealing. The experimental Raman spectra are compared with calculated modes of in-phase bending vibrations generated in gold nanoparticles.

Kurbatova, N. V.; Galyautdinov, M. F.; Ivanov, N. A.; Kolesnikov, S. S.; Papernyi, V. L.; Osin, Yu. N.; Stepanov, A. L.

2013-09-01

279

Cancer Diagnosis by Laser Spectroscopy.  

National Technical Information Service (NTIS)

Significant progress has been achieved to distinguish between cancerous and normal human breast and lung tissues by laser fluorescence spectroscopy. Several spectroscopic methods, such as pulse and CW laser fluorescence spectra, excitation spectra, and pi...

A. Pradhan G. C. Tang J. Chen R. R. Alfano W. Sha

1989-01-01

280

Raman spectroscopy of polystyrene nanofibers—Multiwalled carbon nanotubes composites  

NASA Astrophysics Data System (ADS)

Raman spectroscopy investigations of nanofibers of polystyrene loaded with various amounts of multiwalled carbon nanotubes are reported. The modifications of the main Raman bands (D and G) of multiwalled carbon nanotubes due to their dispersion in polystyrene demonstrates and quantifies the stress transfer from the polymeric nanofiber matrix (polystyrene) to multiwalled carbon nanotubes. TGA data show an increase of the thermal stability of polystyrene nanofibers upon the loading with multiwalled carbon nanotubes, conforming Raman data.

Chipara, Dorina M.; Macossay, Javier; Ybarra, Ana V. R.; Chipara, A. C.; Eubanks, Thomas M.; Chipara, Mircea

2013-06-01

281

Compact Raman spectrometer system for low frequency spectroscopy  

Microsoft Academic Search

We report low frequency Stokes and anti-Stokes Raman spectra resolving frequency shifts down to 15 cm-1 using a standard commercial Raman spectrometer with ultra-narrow band notch filters. The ultra-narrow band notch filters were fabricated holographically in a glass material with optical densities ranging from 4 to 6 per notch filter at the standard Raman laser lines of 488 nm, 532

Christophe Moser; Frank Havermeyer

2010-01-01

282

Passively Mode-Locked Raman Laser  

NASA Astrophysics Data System (ADS)

We report on the observation of a mode-locked laser generated with a crystalline whispering gallery mode resonator pumped with a continuous wave laser. Optical pumping of the resonator generates an optical frequency comb with phase locked components at the Raman offset of the resonator host material. Phase locking of the modes is confirmed via measurement of the radio-frequency beat note produced by the comb on a fast photodiode. Neither the conventional Kerr comb nor hyperparametric oscillation is observed when the comb is present. We present a theoretical explanation of the effect.

Liang, W.; Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

2010-10-01

283

Raman spectroscopy for the detection of cancers and precancers  

Microsoft Academic Search

Optical spectroscopy has been extensively studied as a potential in vivo diagnostic tool that can provide information about both the chemical and morphological structure of tissue in near real time. Most in vivo studies have concentrated on elastic scattering and fluorescence spectroscopies since these signals can be obtained with a good signal-to-noise ratio quickly. However, Raman spectroscopy, an inelastic scattering

Anita Mahadevan-Jansen; Rebecca R. Richards-Kortum

1996-01-01

284

Raman spectroscopy of submicron KNO3 films  

NASA Astrophysics Data System (ADS)

We have obtained Raman spectra of phase-I, -II, and -III KNO3 films 0.26 ?m thick. The primary aim was to establish the physical mechanism for stabilization of the ferroelectric phase III in thin films. In bulk, phase III exists only as a reentrant phase stable from ~113 °C to 120 °C. However, application of hydrostatic or uniaxial pressure greatly enlarges the temperature range over which phase III is stable. This has led to the conjecture that stress (e.g., from differential thermal expansion of film and substrate) stabilizes phase III in thin films. Our vibrational spectroscopy shows that this is not likely to be the dominant effect. The dominant effect appears to be surface electric fields. This is shown in the shift and splitting of low-energy odd-parity modes from an unresolved broad peak at 120 cm-1 in bulk crystals to resolved TO-LO pairs at 92 and 97 cm-1 and 107 and 113 cm-1. The Raman data show that the KNO3 thin films are more highly ordered than in bulk. This is compatible with spontaneous polarization values, which are 50% or more greater in the films, and with much higher TC values in the thinner films. The values of TC as a function of thickness d are compatible with the theory of Tilley and Zeks [Solid State Commun. 49, 823 (1984)] as well as with similar experimental results by Hadni and Thomas [Thin Solid Films 81, 247 (1981); Ferroelectrics 59, 221 (1989)] on triglycine sulfate.

Scott, J. F.; Zhang, Ming-Sheng; Godfrey, R. Bruce; Araujo, C.; McMillan, L.

1987-03-01

285

Theory of Raman scattering with pulses: Application to continuum Raman spectroscopy  

Microsoft Academic Search

A theory of real-time dependence of Raman scattering for a pulse-mode laser is developed within second-order perturbation theory and using the wavepacket terminology. The rate of spontaneous Raman emission with a pulse correctly reduces to the dynamical equivalent of the Kramers-Heisenberg-Dirac expression in the monochromatic limit. We apply the theory to continuum Raman scattering for short and long pulses and

J. Lu; Soo-Y. Lee

1996-01-01

286

Raman Spectroscopy and Microscopic Raman Imaging with Applications of Volume Holographic Optical Elements  

Microsoft Academic Search

Holographic optical elements are crucial for the development of compact and efficient Raman spectroscopic instrumentation. Holographic optics allow direct coupling of a single-stage spectrograph to a Raman microprobe. The high transmission efficiency and narrow rejection-band characteristics of the holographic beam splitter provide efficient use of low power lasers, while allowing acquisition of low-frequency Raman spectra. The holographic notch filter and

David Mark Pallister

1994-01-01

287

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

288

Thermal Dynamics of Graphene Edges Investigated by Polarized Raman Spectroscopy  

Microsoft Academic Search

In this report, we present Raman spectroscopy investigation of the thermal stability and dynamics of graphene edges. It was found that graphene edges (both armchair and zigzag) are not stable and undergo modifications even at temperature as low as 200{\\\\deg}C. Based on polarized Raman results, we provide possible structural models on how graphene edges change during annealing. The zigzag edges

Ya Nan Xu; Da Zhan; Lei Liu; Hui Suo; Zhen Hua Ni; Thuong Thuong Nguyen; Chun Zhao; Ze Xiang Shen

2010-01-01

289

Hydrogen bonding in aqueous ethanol solutions studied by Raman spectroscopy  

Microsoft Academic Search

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

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

2010-01-01

290

Cone penetrometer fiber optic raman spectroscopy probe assembly  

Microsoft Academic Search

A chemically and mechanically robust optical Raman spectroscopy probe assembly that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via fiber optics

Kevin R. Kyle; Steven B. Brown

2000-01-01

291

Cone penetrometer fiber optic Raman spectroscopy probe assembly  

Microsoft Academic Search

A chemically and mechanically robust optical Raman spectroscopy probe assembly is described that can be incorporated in a cone penetrometer (CPT) for subsurface deployment. This assembly consists of an optical Raman probe and a penetrometer compatible optical probe housing. The probe is intended for in-situ chemical analysis of chemical constituents in the surrounding environment. The probe is optically linked via

K. R. Kyle; S. B. Brown

2000-01-01

292

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...

293

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

294

Visible and UV Raman spectroscopy of membrane-bound peptides  

Microsoft Academic Search

Two Raman spectroscopic methods are presented to investigate the structures of membrane- bound peptides. In the first method, water accessibility to each tryptophan side chain of gramicidin A incorporated into phospholipid liposomes has been measured by use of hydrogen-deuterium exchange, selective isotopic labeling, and visible Raman spectroscopy. The water accessibility data are best explained by a newly proposed ion channel

Hideo Takeuchi; Teruhiko Maruyama; Yoshikazu Ohtsuka; Issei Harada

1993-01-01

295

Raman spectroscopy: The effect of field gradient on SERS  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman spectroscopy is normally associated with the enhanced electric fields that arise near metal nanoparticle surfaces. The contribution of field gradients has been unclear, but new research provides insights into their effect.

Aikens, Christine M.; Madison, Lindsey R.; Schatz, George C.

2013-07-01

296

Stimulated Raman gain spectroscopy of GaAs  

SciTech Connect

Applications of stimulated Raman gain spectroscopy to characterization of semiconductor materials is discussed. Results from below-bandgap studies of bulk GaAs are presented, from which scattering mechanisms are deduced.

Beck, S.; Wessel, J.

1986-08-15

297

Two-dimensional electronic femtosecond stimulated Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report two-dimensional electronic spectroscopy with a femtosecond stimulated Raman scattering probe. The method reveals correlations between excitation energy and excited state vibrational structure following photoexcitation. We demonstrate the method in rhodamine 6G.

Wilcox, D. E.; Ogilvie, J. P.

2013-03-01

298

Spectroscopic characterization of biological agents using FTIR, normal Raman and surface-enhanced Raman spectroscopies  

Microsoft Academic Search

FTIR, Raman spectroscopy and Surface Enhanced Raman Scattering (SERS) requires a minimum of sample allows fast identification of microorganisms. The use of this technique for characterizing the spectroscopic signatures of these agents and their stimulants has recently gained considerable attention due to the fact that these techniques can be easily adapted for standoff detection from considerable distances. The techniques also

Tatiana Luna-Pineda; Kristina Soto-Feliciano; Edwin De La Cruz-Montoya; Leonardo C. Pacheco Londoño; Carlos Ríos-Velázquez; Samuel P. Hernández-Rivera

2007-01-01

299

Forensic and homeland security applications of modern portable Raman spectroscopy  

Microsoft Academic Search

Modern detection and identification of chemical and biological hazards within the forensic and homeland security contexts may well require conducting the analysis in field while adapting a non-contact approach to the hazard. Technological achievements on both surface and resonance enhancement Raman scattering re-developed Raman spectroscopy to become the most adaptable spectroscopy technique for stand-off and non-contact analysis of hazards. On

Emad L. Izake

2010-01-01

300

Diagnosis of Basal Cell Carcinoma by Raman Spectroscopy  

Microsoft Academic Search

Skin cancers are the most common form of malignant neoplasms in man. In this work, near-infrared Fourier transform (NIR-FT) Raman spectroscopy was used to study the molecular alterations in the most common skin cancer, basal cell carcinoma (BCC). Biopsies from 16 histopathologically veri-ed BCC and 16 biopsies from normal skin were harvested and analysed by NIR-FT-Raman spectroscopy using a 1064

M. Gniadecka; H. C. Wulf; N. Nymark Mortensen; O. Faurskov Nielsen; D. H. Christensen

1997-01-01

301

Quantitative Raman Spectroscopy of Biomaterials for Arthroplastic Applications  

Microsoft Academic Search

Raman microprobe spectroscopy has considerable potential as an analytical tool in orthopedic science for its capability of\\u000a non-destructively assessing the physical, chemical, and mechanical characteristics of load-bearing parts in arthroplastic\\u000a components (i.e., artificial joints). In comparison to other assessment techniques, Raman spectroscopy offers high spatial\\u000a resolution in the characterization of oxidation states, phase transformations, crystallographic textures, and residual stress\\/strain\\u000a fields

Giuseppe Pezzotti

302

In vitro quantitation of human femoral artery atherosclerosis using near-infrared Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Near-infrared Raman spectroscopy has been used in vitro to identify calcified atherosclerotic plaques in human femoral arteries. Raman techniques allow for the identification of these plaques in a nondestructive manner, which may allow for the diagnosis of coronary artery disease in cardiac patients in the future. As Raman spectroscopy also reveals chemical information about the composition of the arteries, it can also be used as a prognostic tool. The in vivo detection of atherosclerotic plaques at risk for rupture in cardiac patients will enhance treatment methods while improving clinical outcomes for these procedures. Raman spectra were excited by an Invictus 785-nm NIR laser and measured with a fiber-coupled micro-Raman RXN system (Kaiser Optical Systems, Inc., Ann Arbor, MI) equipped with a 785 nm CW laser and CCD detector. Chemical mapping of arteries obtained post mortem allowed for the discrete location of atherosclerotic plaques. Raman peaks at 961 and 1073 cm-1 reveal the presence of calcium hydroxyapatite and carbonate apatite, which are known to be present in calcified plaques. By mapping the locations of these peaks the boundaries of the plaques can be precisely determined. Areas of varying degrees of calcification were also identified. Because this can be useful in determining the degree of plaque calcification and vessel stenosis, this may have a significant impact on the clinical treatment of atherosclerotic plaques in the future.

Dykes, Ava C.; Anastasiadis, Pavlos; Allen, John S., III; Sharma, Shiv K.

2012-05-01

303

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.

2012-05-01

304

The Diagnosis of Lung Cancer Using 1064-nm Excited Near-infrared Multichannel Raman Spectroscopy  

Microsoft Academic Search

Purpose: Raman spectroscopy is based on Raman scattering of light from molecules. Because the wavelength of Raman scattered light depends on molecular composition, Raman spectra provide highly useful information about molecular composition. It has already been shown that Raman spectroscopy is potentially useful for the clinical diagnosis of malignant tumors. However, this technique had never been applied to the diagnosis

Hiroya Yamazaki; Shoji Kaminaka; Ehiichi Kohda; Makio Mukai; Hiro-o Hamaguchi

305

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.

Brauchle, Eva; Schenke-Layland, Katja

2013-01-01

306

Nd:SrWO4 Raman laser  

NASA Astrophysics Data System (ADS)

Properties of the laser operation and simultaneously stimulated Raman scattering in the new SRS-active neodymium doped SrWO4 crystal coherently end-pumped by alexandrite 752 nm laser radiation were investigated. The maximum generated energy 90 mJ from the free-running Nd3+:SrWO4 laser at 1057 nm wavelength was obtained with the output coupler reflectivity 52%. The slope efficiency reached s = 0.52, the beam characteristic parameters M2 and divergence q were 2.5 +/- 0.1, and 1.5 +/- 0.1 mrad, respectively. Maximal output energy of 1.46 mJ for the fundamental wavelength was obtained for Q-switched Nd3+:SrWO4 oscillator with a double Fabry-Perrot as the output coupler (R = 48%), and with the 5% initial transmission of LiF:F2- saturable absorber. Up to 0.74 mJ energy was registered at the first Stokes frequency. The pulse duration was 5 ns and 2.4 ns for the fundamental and Stokes radiation, respectively. The energy of 1.25 mJ at 1170 nm was obtained for closed Raman resonator with special mirrors. For the case of mode-locking, two dye saturable absorbers (ML51 dye in dichlorethan and 3955 dye in ethanol) were used and SRS radiation in the form of pulse train was observed. The influence of the various Raman laser output couplers reflectivity as well as the initial transmissions of passive absorbers were investigated with the goal of the output energy maximization at the Stokes wavelength. In the output, the total measured energy was 1.8 mJ (for ML51 dye) and 2.4 mJ (for 3955 dye). The SRS output at 1170 nm was approximately 20% of total energy.

Jelinkova, Helena; Sulc, Jan; Doroschenko, Maxim E.; Skornyakov, Vadim V.; Kravtsov, Sergey B.; Basiev, Tasoltan T.; Zverev, Peter G.

2004-09-01

307

Gaseous trace analysis using pulsed photoacoustic Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The paper describes a method for the trace analysis of gases, based on the pulsed photoacoustic Raman spectroscopy (PARS) technique. It is reported that the method has been applied to the analysis of mixtures of CH4 in N2, CO2 in N2, and N2O in N2 at concentrations near 1 ppm. Attention is given to the apparatus used and means of improving the method's sensitivity as well as sensitivity-limiting processes are evaluated. Finally, the analytical capabilities of this technique are compared with both direct (IR) absorption and other Raman techniques such as CARS and stimulated Raman gain spectroscopy (SRGS).

Siebert, D. R.; West, G. A.; Barrett, J. J.

1980-01-01

308

On the Contribution of Raman Spectroscopy to Forensic Science  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has only recently sparked interest from forensic laboratories. The Raman technique has demonstrated important advantages such as its nondestructive nature, its fast analysis time, and especially the possibility of performing microscopical in situ analyses. In forensic applications, it is a versatile technique that covers a wide spectrum of substances such as trace evidence, illicit drugs and inks. An overview of the recent developments of Raman spectroscopy in forensic science will be discussed. Also, the requirements for an analytical technique for the examination of physical evidence will be described. Examples of casework will be depicted.

Buzzini, Patrick; Massonnet, Genevieve

2010-08-01

309

Scanning-probe Raman spectroscopy with single-molecule sensitivity  

NASA Astrophysics Data System (ADS)

Single-molecule vibrational Raman spectroscopy of malachite green adsorbed on planar metal surfaces is achieved by means of optical local-field enhancement provided by a scanning nanoscopic metallic tip. The single-molecule signature is evident from spectral diffusion and a discretization of Raman peak intensities. The optical tip-sample coupling gives rise to a localization of the response down to a sub- 10nm length scale and a Raman enhancement up to ˜5×109 . This combines vibrational spectroscopy with high resolution scanning-probe microscopy for ultrasensitive in situ analysis of individual molecules.

Neacsu, Catalin C.; Dreyer, Jens; Behr, Nicolas; Raschke, Markus B.

2006-05-01

310

Polarization Raman spectroscopy of GaN nanorod bundles  

SciTech Connect

We performed polarization Raman spectroscopy on single wurtzite GaN nanorod bundles grown by plasma-assisted molecular beam epitaxy. The obtained Raman spectra were compared with those of GaN epilayer. The spectral difference between the GaN nanorod bundles and epilayer reveals the relaxation of Raman selection rules in these GaN nanorod bundles. The deviation of polarization-dependent Raman spectroscopy from the prediction of Raman selection rules is attributed to both the orientation of the crystal axis with respect to the polarization vectors of incident and scattered light and the structural defects in the merging boundary of GaN nanorods. The presence of high defect density induced by local strain at the merging boundary was further confirmed by transmission electron microscopy. The averaged defect interspacing was estimated to be around 3 nm based on the spatial correlation model.

Tite, T.; Lee, C. J.; Chang, Y.-M. [Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China)

2010-08-15

311

Raman forward scattering of chirped laser pulses  

SciTech Connect

Raman scattering of a high-intensity, short duration, frequency-chirped laser pulse propagating in an underdense plasma is examined. The growth of the direct forward scattered light is calculated for a laser pulse with a linear frequency chirp in various spatio-temporal regimes. This includes a previously undescribed regime of strongly-coupled four-wave nonresonant interaction, which is important for relativistic laser intensities. In all regimes of forward scattering, it is shown that the growth rate increases (decreases) for positive (negative) frequency chirp. The effect of chirp on the growth rate is relatively minor, i.e., a few percent chirp yields few percent changes in the growth rates. Numerical solutions based on fully nonlinear cold Maxwell-fluid model are presented which confirm analytical predictions. Relation of these results to recent experiments is discussed.

Schroeder, C.B.; Esarey, E.; Shadwick, B.A.; Leemans, W.P.

2002-12-05

312

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

313

BRIEF COMMUNICATIONS: Raman laser as an efficient source for the excitation of stimulated Raman scattering spectra  

Microsoft Academic Search

Raman lasers with liquid carbon disulfide, nitromethane, benzene, and nitrobenzene active media were used to excite stimulated Raman spectra in crystalline transparent and absorbing matrices. The high efficiency of these lasers in this application was noted and a qualitative physical interpretation of the observed phenomena was developed. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find

Yakov S. Bobovich; A. V. Bortkevich; V. I. Petrov

1978-01-01

314

Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds  

Microsoft Academic Search

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser detection. Standoff distances for pulsed measurements were

William Ortiz-Rivera; Leonardo C. Pacheco-Londoño; Samuel P. Hernández-Rivera

2010-01-01

315

Mode-dependent dispersion in Raman line shapes: Observation and implications from ultrafast Raman loss spectroscopy  

SciTech Connect

Ultrafast Raman loss spectroscopy (URLS) enables one to obtain the vibrational structural information of molecular systems including fluorescent materials. URLS, a nonlinear process analog to stimulated Raman gain, involves a narrow bandwidth picosecond Raman pump pulse and a femtosecond broadband white light continuum. Under nonresonant condition, the Raman response appears as a negative (loss) signal, whereas, on resonance with the electronic transition the line shape changes from a negative to a positive through a dispersive form. The intensities observed and thus, the Franck-Condon activity (coordinate dependent), are sensitive to the wavelength of the white light corresponding to a particular Raman frequency with respect to the Raman pump pulse wavelength, i.e., there is a mode-dependent response in URLS.

Umapathy, S.; Mallick, B.; Lakshmanna, A. [Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore 560012 (India)

2010-07-14

316

Theory of femtosecond coherent anti-Stokes Raman scattering spectroscopy of gas-phase transitions.  

PubMed

A theoretical analysis of coherent anti-Stokes Raman scattering (CARS) spectroscopy of gas-phase resonances using femtosecond lasers is performed. The time-dependent density matrix equations for the femtosecond CARS process are formulated and manipulated into a form suitable for solution by direct numerical integration (DNI). The temporal shapes of the pump, Stokes, and probe laser pulses are specified as an input to the DNI calculations. It is assumed that the laser pulse shapes are 70 fs Gaussians and that the pulses are Fourier-transform limited. A single excited electronic level is defined as an effective intermediate level in the Raman process, and transition strengths are adjusted to match the experimental Raman polarizability. The excitation of the Raman coherence is investigated for different Q-branch rotational transitions in the fundamental 2330 cm(-1) band of diatomic nitrogen, assuming that the pump and Stokes pulses are temporally overlapped. The excitation process is shown to be virtually identical for transitions ranging from Q2 to Q20. The excitation of the Raman coherences is also very efficient; for laser irradiances of 5x10(17) W/m2, corresponding approximately to a 100 microJ, 70 fs pulse focused to 50 microm, approximately 10% of the population of the ground Raman level is pumped to the excited Raman level during the impulsive pump-Stokes excitation, and the magnitude of the induced Raman coherence reaches 40% of its maximum possible value. The theoretical results are compared with the results of experiments where the femtosecond CARS signal is recorded as a function of probe delay with respect to the impulsive pump-Stokes excitation. PMID:17672699

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

2007-07-28

317

Recent Development on Silicon Raman Lasers and Amplifiers  

Microsoft Academic Search

Silicon photonics has made rapid progress in recent years achieving several key breakthroughs. Chip-scale silicon lasers and amplifiers based on stimulated Raman scattering have been successfully demonstrated. Recent development of Raman silicon lasers and amplifiers based on ring resonator architecture enables dimension scalability and monolithic integration with other photonics components

Haisheng Rong; Ying-Hao Kuo; Shengbo Xu; Oded Cohen; Omri Raday; Mario Paniccia

2006-01-01

318

Observation of pulsating instabilities in an intracavity Raman laser  

NASA Astrophysics Data System (ADS)

An intracavity Raman laser as a dynamical system with stochastic behaviour is investigated. Pulsating instabilities, mode-locking and possible features of a chaotic behaviour of the Q-switched ruby laser induced by intracavity stimulated Raman scattering are observed. Institute of Nuclear Problems, Byelorussian State University 220080 Minsk, Bobruyskaya 11, USSR.

Chizhevsky, V. N.; Gakhovich, D. E.; Grabchikov, A. S.; Kilin, S. Ya.; Orlovich, V. A.; Tomilchik, L. L.

1991-07-01

319

Application of UV-Raman spectroscopy to the detection of chemical and biological threats  

NASA Astrophysics Data System (ADS)

Brookhaven National Laboratory (BNL), Edgewood Chemical and Biological Center (ECBC) and ITT Industries Advanced Engineering and Sciences Division (AES) have been collaborating on the transitioning and subsequent development of a short-range, non-contact Raman lidar system specifically designed to detect and identify chemical agents on the battlefield. [The instrument, referred to as LISA (Laser Interrogation of Surface Agents), will the subject of an accompanying paper.] As part of this collaboration, BNL has the responsibility for developing a spectral database (library) of surrogates and precursors for use with LISA"s pattern recognition algorithms. In this paper, the authors discuss the phenomenon of UV Raman and resonance-enhanced Raman spectroscopy, the development of an instrument-independent Raman spectral library, and highlight the exploitable characteristics present in the acquired spectral signatures that suggest potential utility in our country"s efforts on Homeland Security.

Sedlacek, Arthur J., III; Christesen, Steven D.; Chyba, Tom; Ponsardin, Pat

320

Collective electronic excitations in magnetically aligned single wall carbon nanotubes studied by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Samples with magnetically aligned single wall carbon nanotubes (SWNT) have been studied by Raman spectroscopy in the low frequency spectral range: 10 - 700 cm-1. A novel Raman-active electronic collective excitation has been observed. At room temperature the excitation band is at about 30 cm-1. The band dramatically strengthens and softens down to about 15 cm-1 with sample cooling below 50 K. The polarization dependence of the Raman spectra was analyzed for laser excitation energies in resonance with electronic transitions and it was compared to that in the case of non-resonant excitation. Strong anisotropy of Raman response function of the SWNT has been observed: for polarization parallel to the direction of the nanotubes the electronic excitation band is about 4 times stronger than that for the perpendicular direction. The origin of the 1-D electronic excitation in metallic SWNT will be discussed.

Blumberg, G.; Gozar, A.; Dennis, B. S.; Sirenko, A. A.; Eklund, P. C.; Walters, D. A.; Casavant, M. J.; Schmidt, J.; Smalley, R. E.

2001-03-01

321

Picosecond time-resolved pure-rotational coherent anti-Stokes Raman spectroscopy for N(2) thermometry.  

PubMed

Time-resolved pure-rotational coherent anti-Stokes Raman spectroscopy using picosecond-duration laser pulses is investigated for gas thermometry. The use of picosecond laser pulses significantly reduces background caused by scattering of the probe beam, and delayed probing of the Raman coherence enables elimination of interference from nonresonant four-wave mixing processes. Temperatures inferred from rotational spectra are sensitive to the probe delay because of the rotational-level dependence of collisional dephasing of Raman coherences. The sensitivity decreases, however, with increasing temperature, and accurate temperature measurements in a flame are demonstrated using a standard frequency-domain analysis of the spectra. PMID:19953185

Seeger, Thomas; Kiefer, Johannes; Leipertz, Alfred; Patterson, Brian D; Kliewer, Christopher J; Settersten, Thomas B

2009-12-01

322

Quantitative and qualitative analysis of fluorescent substances and binary mixtures by use of shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

Shifted Excitation Raman Difference Spectroscopy (SERDS) implemented with two wavelength-stabilized laser diodes with fixed wavelength separation is discussed as an effective method for dealing with the effects of fluorescence in Raman spectroscopic analysis. In this presentation we discuss the results of both qualitative and quantitative SERDS analysis of a variety of strongly fluorescing samples, including binary liquid mixtures. This application is enabled by the Volume Bragg Grating® (VBG®) technology, which allows manufacturing of compact low-cost high-power laser sources, suitable for extending the SERDS methodology to portable Raman spectrometers.

Volodin, Boris L.; Dolgy, Sergei; Lieber, Chad; Wu, Huawen; Yang, William

2013-03-01

323

Near-infrared Raman spectroscopy detects lung cancer  

NASA Astrophysics Data System (ADS)

This work was to explore near-infrared (NIR) Raman spectroscopy for distinguishing tumor from normal bronchial tissue. A rapid NIR Raman system was used for tissue Raman studies. High-quality Raman spectra in the 700-1800 cm-1 range can be acquired from human bronchial tissues in vitro. Raman spectra differed significantly between normal and malignant tumor tissue, with tumors showing increased nucleic acid, tryptophan, phenylalanine signals and decreased phospholipids, proline, and valine signals than normal tissue. Raman spectral shape differences between normal and tumor tissue were also observed particularly in the spectral ranges of 1000-1100, 1200-1400, and 1500-1700 cm-1, which are related to the protein and lipid conformations and CH stretching modes in nucleic acids. The ratio of Raman intensities at 1445 cm-1 to 1655 cm-1 provided good differentiation between normal and malignant bronchial tissue, suggesting that NIR Raman spectroscopy may have a significant potential for the noninvasive diagnosis of lung cancer in vivo based on optical evaluation of biomolecules.

Huang, Zhiwei; Lui, Harvey; McWilliams, Annette; Lam, Stephen; McLean, David I.; Zeng, Haishan

2005-01-01

324

Correlation of Raman and X-ray diffraction measurements of annealed pulsed laser deposited ZnO thin films  

Microsoft Academic Search

Raman spectroscopy, X-ray diffractometry and atomic force microscopy have been used to characterise ZnO thin films grown by pulsed laser deposition as a function of the post-growth annealing temperature. The results show substantial enhancement and broadening of certain Raman features which correlate excellently with the change in width of the X-ray diffraction peaks. The 570 cm?1 Raman feature showed pronounced

C. Roy; S. Byrne; E. McGlynn; J.-P. Mosnier; E. de Posada; D. O'Mahony; J. G. Lunney; M. O. Henry; B. Ryan; A. A. Cafolla

2003-01-01

325

Raman Spectroscopy for the Undergraduate Teaching Laboratory: Quantification of Ethanol Concentration in Consumer Alcoholic Beverages and Qualitative Identification of Marine Diesels Using a Miniature Raman Spectrometer  

Microsoft Academic Search

Raman spectroscopy has steadily gained popularity as a powerful tool in both the analytical lab and the undergraduate classroom. The technique is attractive because it allows for rapid, nondestructive qualitative or quantitative analyses of many analytes with little or no sample preparation requirements. The introduction of less expensive, smaller, and more powerful diode laser excitation sources and the recent availability

Danielle Cleveland; Matthew Carlson; Evan D. Hudspeth; Lauren E. Quattrochi; Kathleen L. Batchler; Shrimati A. Balram; Seongun Hong; Robert G. Michel

2007-01-01

326

Raman Spectroscopy of Lithium Hydride Corrosion: Selection of an Appropriate Excitation Wavelength to Minimize Fluorescence  

SciTech Connect

The recent interest in a hydrogen-based fuel economy has renewed research into metal hydride chemistry. Many of these compounds react readily with water to release hydrogen gas and form a caustic. Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFT) has been used to study the hydrolysis reaction. The LiOH stretch appears at 3670 cm{sup -1}. Raman spectroscopy is a complementary technique that employs monochromatic excitation (laser) allowing access to the low energy region of the vibrational spectrum (<600 cm{sup -1}). Weak scattering and fluorescence typically prevent Raman from being used for many compounds. The role of Li{sub 2}O in the moisture reaction has not been fully studied for LiH. Li{sub 2}O can be observed by Raman while being hidden in the Infrared spectrum.

Stowe, A. C.; Smyrl, N. R.

2011-05-26

327

Raman spectroscopy of individual monocytes reveals that single-beam optical trapping of mononuclear cells occurs by their nucleus  

NASA Astrophysics Data System (ADS)

We show that laser tweezers Raman spectroscopy of eukaryotic cells with a significantly larger diameter than the tight focus of a single-beam laser trap leads to optical trapping of the cell by its optically densest part, i.e. typically the cell's nucleus. Raman spectra of individual optically trapped monocytes are compared with location-specific Raman spectra of monocytes adhered to a substrate. When the cell's nucleus is stained with a fluorescent live cell stain, the Raman spectrum of the DNA-specific stain is observed only in the nucleus of individual monocytes. Optically trapped monocytes display the same behavior. We also show that the Raman spectra of individual monocytes exhibit the characteristic Raman signature of cells that have not yet fully differentiated and that individual primary monocytes can be distinguished from transformed monocytes based on their Raman spectra. This work provides further evidence that laser tweezers Raman spectroscopy of individual cells provides meaningful biochemical information in an entirely non-destructive fashion that permits discerning differences between cell types and cellular activity.

Fore, Samantha; Chan, James; Taylor, Douglas; Huser, Thomas

2011-04-01

328

Laser Raman studies of RNA backbone ordering in Escherichia coli ribosomes  

SciTech Connect

Although the primary structures of ribosomal RNA and r-proteins are rapidly being elucidated and the secondary structure of the ribosome is under intense investigation by numerous techniques, the tertiary structure of the ribosome is largely unknown. Here we present evidence that Laser Raman (LR) spectroscopy may allow the semiquantitative assessment of features of tertiary structure in a variety of environmental conditions.

King, T.C. (Washington Univ., St. Louis, MO); Schlessinger, D.; Milanovich, F.

1980-10-01

329

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

330

Examination of cellulose textile fibres in historical objects by micro-Raman spectroscopy.  

PubMed

The investigation and characterisation of historical objects can be an exacting piece of work because of the small quantity of material that can be investigated and the degradation of the material and its value, which sometimes demands only non-destructive methods. In this study, as one such method, Raman spectroscopy was used to investigate the cellulose fibres of painting canvases and linings. Historical samples of fabrics were taken from different paintings and their linings from different locations in Slovenia. Raman spectra were recorded on the fibres of these historical samples. Additionally, a database of the Raman spectra of modern cellulose fibres was created and compared with the literature data. Differences in the Raman spectra of different cellulose fibres were observed, and on this basis fibres of different types were discriminated. The recorded Raman spectra of historical samples were compared with the database spectra of modern cellulose fibres. Strong luminescence effects because of the changes caused by ageing, degradation products and surface contamination caused difficulties in interpreting the Raman spectra of historical fibres. The luminescence effects were partly overcome by prolonged exposition times and previous "signal quenching" with the laser. The Raman spectra of historical cotton showed no luminescence effects, and only slight differences to the reference spectra of modern cotton fibres appeared, whereas the Raman spectra of historical flax fibres were overwhelmed with luminescence and showed changes in spectra through degradation. The research showed that by using Raman spectroscopy the identification and differentiation of different cellulose fibres and materials that accompany cellulose in the fibres are possible and that degraded and aged material can be differentiated. PMID:21190892

Kavkler, Katja; Demšar, Andrej

2010-12-14

331

Raman spectroscopy of MnWO4  

NASA Astrophysics Data System (ADS)

The polarized Raman spectra of MnWO4 single crystals were studied between 5 and 300 K. All 8Ag+10Bg Raman active modes were identified and assigned to definite atomic motions in close comparison with the frequencies and eigenvectors predicted by shell model calculations. No detectable phonon anomalies were observed near the three successive magnetic and ferroelectric transitions at 13.5, 12.5, and 6.8 K.

Iliev, M. N.; Gospodinov, M. M.; Litvinchuk, A. P.

2009-12-01

332

Detection of biosignatures in silicified rocks using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In this study, we demonstrate the usefulness of Raman spectroscopy, and in particular Raman mapping, as a very powerful tool for the study of both organic matter and minerals associated with silicified biological remains. Our investigations concern silicified organic matter, microorganisms and biological remains of various origins and ages, from the metacherts of Isua, Greenland, 3.8 Ga, to silicified wood from the Petrified Forest National Park, Arizona, USA, 225 Ma.

Foucher, F.; Westall, F.

2012-09-01

333

Raman spectroscopy studies of Er 3+-doped zinc tellurite glasses  

Microsoft Academic Search

Er3+-doped tellurite-based glasses have been investigated using Raman spectroscopy. The study is aimed to determine the structural characteristics of systems with broad Er3+ emission bands. In the Er2O3 concentration 0.5–4mol% range studied, experimental results showed that adding erbium ions to zinc tellurite glass converts TeO4 trigonal bipyramid (tbp) units into TeO3 trigonal pyramid (tp) groups. A Raman band, associated with

N. Jaba; A. Mermet; E. Duval; B. Champagnon

2005-01-01

334

An efficient setup for femtosecond stimulated Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We present an efficient and robust setup for femtosecond stimulated Raman (FSR) spectroscopy with 60 fs and 10 cm-1 resolution. Raman pulses of 0.5-5 ps are tunable between 450-750 nm with energies1-10 ?J. Experimental features of the setup, signal processing, and data treatment are discussed in detail to be readily reproduced in other labs. The setup is tested by measuring FSR spectra of stilbene in solution.

Kovalenko, S. A.; Dobryakov, A. L.; Ernsting, N. P.

2011-06-01

335

Micro-Raman spectroscopy: a powerful technique for materials research  

Microsoft Academic Search

Since the development of the holographic notch filters during the last decade and novel detectors such as charge coupled devices, Raman spectroscopy instrumentation has evolved rapidly, so that modern spectrometers are orders of magnitude faster, present much lower signal-to-noise ratio and simplified optics than their predecessors. These advances have also had a significant effect in the construction of novel micro-Raman-dedicated

S Jimenez-Sandoval

2000-01-01

336

Multivariate prediction of clarified butter composition using raman spectroscopy  

Microsoft Academic Search

Raman spectroscopy has been used to predict the abundance of the FA in clarified butterfat that was obtained from dairy cows\\u000a fed a range of levels of rapeseed oil in their diet. Partial least squares regression of the Raman spectra against FA compositions\\u000a obtained by GC showed that good prediction of the five major (abundance >5%) FA gave R\\u000a 2=0.74–0.92

J. Renwick Beattie; Steven E. J. Bell; C. Borgaard; A. M. Fearon; Bruce W. Moss

2004-01-01

337

Discrimination analysis of human lung cancer cells associated with histological type and malignancy using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The Raman spectroscopic technique enables the observation of intracellular molecules without fixation or labeling procedures in situ. Raman spectroscopy is a promising technology for diagnosing cancers-especially lung cancer, one of the most common cancers in humans-and other diseases. The purpose of this study was to find an effective marker for the identification of cancer cells and their malignancy using Raman spectroscopy. We demonstrate a classification of cultured human lung cancer cells using Raman spectroscopy, principal component analysis (PCA), and linear discrimination analysis (LDA). Raman spectra of single, normal lung cells, along with four cancer cells with different pathological types, were successfully obtained with an excitation laser at 532 nm. The strong appearance of bands due to cytochrome c (cyt-c) indicates that spectra are resonant and enhanced via the Q-band near 550 nm with excitation light. The PCA loading plot suggests a large contribution of cyt-c in discriminating normal cells from cancer cells. The PCA results reflect the nature of the original cancer, such as its histological type and malignancy. The five cells were successfully discriminated by the LDA.

Oshima, Yusuke; Shinzawa, Hideyuki; Takenaka, Tatsuji; Furihata, Chie; Sato, Hidetoshi

2010-01-01

338

Detection of Leukemia with Blood Samples Using Raman Spectroscopy and Multivariate Analysis  

NASA Astrophysics Data System (ADS)

The use of Raman spectroscopy to analyze blood biochemistry and hence distinguish between normal and abnormal blood was investigated. Blood samples were obtained from 6 patients who were clinically diagnosed with leukemia and 6 healthy volunteers. The imprint was put under the microscope and several points were chosen for Raman measurement. All the spectra were collected by a confocal Raman micro-spectroscopy (Renishaw) with a 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) are 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. The preliminary results suggest that Raman Spectroscopy could be a new technique to study the degree of damage to the bone marrow using just blood samples instead of biopsies, treatment very painful for patients.

Martínez-Espinosa, J. C.; González-Solís, J. L.; Frausto-Reyes, C.; Miranda-Beltrán, M. L.; Soria-Fregoso, C.; Medina-Valtierra, J.

2009-06-01

339

Study on laser atomic spectroscopy.  

National Technical Information Service (NTIS)

Laser atomic spectroscopic study on actinium element has been performed in many areas of spectroscopy. The study on characteristics of atomic vapor has been done for copper atom and the spatial density distribution of copper vapor is measured. This experi...

H. K. Cha K. S. Song D. Y. Jeong J. Lee J. H. Yi

1993-01-01

340

Cancer Diagnosis by Laser Spectroscopy.  

National Technical Information Service (NTIS)

The objective of this project is to investigate and develop novel optically based diagnostics modalities to distinguish between normal and cancerous tissues using various types of steady state and ultrafast laser spectroscopy. Significant work has been co...

R. R. Alfano

1990-01-01

341

Non-Contact and Non-Destructive Characterization of Shallow Implanted Silicon PN Junctions using Ultra-Violet Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Ultra-shallow boron implanted (B+ 1 keV 1×1015 cm-2) n-type Si wafers were prepared and characterized by four point probe, SIMS and 363.8 nm excited ultra-violet (UV) Raman spectroscopy before and after rapid thermal annealing (RTA). The penetration depth of 363.8 nm laser radiation in a backscattering Raman configuration, is approximately 5 nm. As junction depth increases from high temperature RTA, sheet resistance decreases. Raman peaks shift in the lower wavenumber direction and its full-width-at-half-maximum (FWHM) broadens. There is clear correlation between junction depth and Raman spectra data. UV Raman spectroscopy can be used as a very powerful non-contact, non-destructive, in-line characterization and monitoring technique for ultra-shallow junctions (USJs).

Fukumoto, Masashi; Hasuike, Noriyuki; Harima, Hiroshi; Yoshimoto, Masahiro; Yoo, Woo Sik

2011-01-01

342

Near-field Raman spectroscopy using a tetrahedral SNOM tip  

NASA Astrophysics Data System (ADS)

An example of near-field Raman spectroscopy based on the tip-enhancement at an apertureless tetrahedral scanning near-field optical tip (t-tip) is presented. Tip-enhanced Raman spectroscopy (TERS) is based on the excitation of localized surface plasmons (LSP) in the cavity of tip and surface. The LSP provide a highly confined and large field enhancement at the tip apex which allows molecular spectroscopy at the nanoscale. The t-tip consists, in contrast to other TERS configurations which use opaque tips, of a gold coated glass tip which is irradiated from the inside. We demonstrate TERS spectra of the dye malachite green isothiocyanate and show an increased bleaching of the dye in presence of the tip. Data analysis show that the actual experimental conditions support moderate enhancement of the Raman signal.

Klein, Stefan; Reichert, Joachim; Fuchs, Harald; Fischer, Ulrich

2006-05-01

343

Surface-enhanced Raman spectroscopy using gold-coated horizontally aligned carbon nanotubes  

Microsoft Academic Search

Gold-coated horizontally aligned carbon nanotube (Au-HA-CNT) substrates were fabricated for surface-enhanced Raman spectroscopy (SERS). The Au-HA-CNT substrates, which are granular in nature, are easy-to-prepare with large SERS-active area. Enhancement factors (EFs) of ?107 were achieved using the Au-HA-CNTs as substrates for rhodamine 6G (R6G) molecules. Maximum enhancement was found when the polarization direction (E-field) of the incident laser beam was

X N He; Y Gao; M Mahjouri-Samani; P N Black; J Allen; M Mitchell; W Xiong; Y S Zhou; L Jiang; Y F Lu

2012-01-01

344

Sensitive and selective chem\\/bio sensing based on surface-enhanced Raman spectroscopy (SERS)  

Microsoft Academic Search

This paper summarizes our recent progress toward developing anthrax and glucose sensors based on surface-enhanced Raman spectroscopy (SERS). Ag film over nanosphere (AgFON) substrates was used as the SERS sensor platform in both cases. The AgFON substrates have been optimized for near-infrared (NIR) laser excitations by tuning the extinction maximum of their localized surface plasmon resonance (LSPR). Bacillus subtilis spores,

Xiaoyu Zhang; Nilam C. Shah; Richard P. Van Duyne

2006-01-01

345

Performance of a spatial-filter-equipped single monochromator for Raman spectroscopy  

Microsoft Academic Search

A technique for reducing stray-light artifacts in Raman spectroscopy is described. The performance of a spatial filter at the output of a single monochromator is reported. The filter reduces both the diffuse background and the scattered-light artifacts encountered in single monochromators while maintaining high luminous throughput. Unlike other wavelength-selective methods for rejecting laser-excitation light (such as use of holographic edge

Mark O. Trulson; Horst B. Lueck; Donald M. Friedrich

1994-01-01

346

Raman spectroscopy of amorphous, nanostructured, diamond-like carbon, and nanodiamond: One contribution of 13 to a Theme 'Raman spectroscopy in carbons: from nanotubes to diamond'  

Microsoft Academic Search

Raman spectroscopy is a standard characterization technique for any carbon system. Here we review the Raman spectra of amorphous, nanostructured, diamond-like carbon and nanodiamond. We show how to use resonant Raman spectroscopy to determine structure and composition of carbon films with and without nitrogen. The measured spectra change with varying excitation energy. By visible and ultraviolet excitation measurements, the G

Andrea Carlo Ferrari; John Robertson

2004-01-01

347

Raman mapping of laser-induced changes and ablation of InAs nanowires  

NASA Astrophysics Data System (ADS)

Indium arsenic (InAs) nanowires were irradiated with a focused laser beam, followed by in situ Raman spectroscopy mapping and scanning electron microscopy imaging to investigate the changes of the nanowires due to laser irradiation. It was found that laser irradiation with the power intensity above a certain threshold causes arsenic (As) atoms to disintegrate from InAs and accumulate on the surface of the nanowire; the accumulated As atoms evaporate under the continued laser irradiation. This process reduces the As content in the nanowire. The reduction of As content, in turn, lowers the melting temperature of the nanowire locally and facilitates laser ablation, which eventually fractures the nanowire. The laser irradiation induced changes of the InAs nanowires are attributed to the local temperature rises due to the irradiation, as confirmed by the Raman peak shifts. The results from this work show that in situ Raman spectroscopy mapping can provide detailed information about the entire process of laser-induced change and ablation of InAs nanowires and has the potential to become a powerful tool for the characterization of laser modification of nanowires and other nanometer-sized objects.

He, Jiayu; Chen, Pingping; Lu, Wei; Dai, Ning; Zhu, Da-Ming

2013-08-01

348

Investigation of structural phase transition in polycrystalline SrTiO 3 thin films by Raman spectroscopy  

Microsoft Academic Search

Polycrystalline SrTiO3 thin films were prepared by pulsed laser deposition technique. The phonon properties and structural phase transition were studied by Raman spectroscopy. The first-order Raman scattering, which is forbidden in SrTiO3 single crystal, has been observed in the films, due to the structural distortion caused by strain effect and oxygen vacancies. The Fano-type line shape of TO2 phonon reveals

Y. L. Du; G. Chen; M. S. Zhang

2004-01-01

349

Picosecond Dynamics of G-Protein Coupled Receptor Activation in Rhodopsin from Time-Resolved UV Resonance Raman Spectroscopy †  

Microsoft Academic Search

The protein response to retinal chromophore isomerization in the visual pigment rhodopsin is studied using picosecond time-resolved UV resonance Raman spectroscopy. High signal-to-noise Raman spectra are obtained using a 1 kHz Ti:Sapphire laser apparatus that provides <3 ps visible (466 nm) pump and UV (233 nm) probe pulses. When there is no time delay between the pump and probe events,

Judy E. Kim; Duohai Pan; Richard A. Mathies

2003-01-01

350

Fuel vapor measurements by linear Raman spectroscopy using spectral discrimination from droplet interferences.  

PubMed

Vapor-phase measurements by linear Raman spectroscopy are performed in the vicinity of methanol droplets. Several types of interference by these droplets are identified and removed by appropriate filtering. This procedure, together with the phase-dependent spectral shift of the OH stretching vibration frequency, is proved to permit single-pulse linear Raman measurements of methanol vapor and nitrogen on a line with coexisting droplets. Laser-induced droplet breakdown is found to limit the applicable laser irradiance to approximately 2 GW/cm(2) and is avoided by use of a flash-lamp-pumped dye laser with high energy (1-7 J) and long pulses (1.5 micross). PMID:18305710

Mewes, B; Bauer, G; Brüggemann, D

1999-02-20

351

Multi-wavelength enhancement of silicon Raman scattering by nanoscale laser surface ablation  

NASA Astrophysics Data System (ADS)

In this paper, we produce nanoholes on a silicon surface by laser ablation. Those nanoholes lead to a yield enhancement of light–matter interaction. Performing Raman spectroscopy on silicon, an enhancement of its main Raman mode is observed: it is twice higher with the nanoholes compared to a flat surface. Such a feature appears whatever the excitation wavelength (488, 514.5 and 632.8 nm) and the laser power, revealing a broad band light–matter interaction enhancement. In addition, no change in the position and shape of the main Raman mode of silicon is observed, suggesting that no structural damages are induced by laser ablation. These results clearly demonstrate the potentiality of such nanostructures for the further development of silicon photonics.

Merlen, A.; Sangar, A.; Torchio, P.; Kallepalli, L. N. D.; Grojo, D.; Utéza, O.; Delaporte, P.

2013-11-01

352

Quantitative and qualitative analysis of urine component in the toilet set using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

As a part of non-invasive and unaware measurement of physiological signal in the house of live-alone person, Raman spectroscopy was applied for urine component analysis in the toilet set. 785nm, 250-300mW output solid state diode laser and 2048 element linear silicon TE cooled CCD array were incorporated for this system. Several tests were performed for setting up Raman spectroscopy in non-constrained situation: toilet set in the house. The effect of dark current, integration time, warming up time of laser, property of probe and interference of water in the toilet were tested and controlled for appropriate measurement in this environment. The spectra were obtained immediately when the subject uses the toilet set, and they can be transmitted to the server though Bluetooth. Those spectra were pre-processed for removing or correcting the effect of undesired light scattering, sample path-length difference and baseline-effect. The preprocessed data were enhanced for more exact result of multivariate analysis. The training data was prepared for predicting unknown component and its concentration by using multivariate methods. Several kinds of multivariate methods: PCA, PCR, PLS were performed to validate what is the fittest method in this environment. Through quantitative and qualitative analysis of Raman spectroscopy"s spectra obtained in the house's toilet set, we could know the component and its concentration of urine which can be index of disease.

Chung, So Hyun; Park, Kwang Suk; Choi, Jong Min; Lee, Won Jin

2004-07-01

353

Characterization by /sup 51/V solid-state NMR, laser Raman, and x-ray photoelectron spectroscopy of vanadium species deposited on. gamma. -Al/sub 2/O/sub 3/  

SciTech Connect

By use of a fluidized bed technique, two series of V/sub 2/O/sub 5/-..gamma..-Al/sub 2/O/sub 3/ samples have been prepared with a vanadate solution at pH 4 or 10. Considering that, for all the prepared samples, an equilibrium between the vanadate species in solution and those adsorbed on the alumina surface exists, the deposited vanadate species are well dispersed. They have been characterized by /sup 51/V solid-state NMR and laser Raman spectroscopy. It was concluded in particular that a strong interaction exists between the oxovanadate species and the support during the impregnation step. The structure of those adsorbed species depends on the pH of the impregnating solution; at pH 10 the major adsorbed species is in a distorted tetrahedral symmetry, whereas at pH 4 the adsorbed species is mainly a polyoxovanadate-like species with vanadium in a distorted octahedral environment. Hydration-dehydration reactions of the supported oxovanadium species have also been evidenced.

Le Coustumer, L.R.; Taouk, B.; Le Meur, M.; Payen, E.; Guelton, M.; Grimblot, J.

1988-03-10

354

Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy.  

PubMed

We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm(-1) wavenumber region about 500, 1150, 1490 and 2000 cm(-1), which we assigned to the out-of-plane deformation and the stretching vibration of the phenyl rings, to the stretching vibration of C-N bonds or the stretching and wagging vibration of CH2, and to overtone or combination bands. Interestingly, we also show that the Raman spectrum of synthetic trichochrome F, a pigment that may be produced along with pheomelanin during pheomelanogenesis, is different from that of pheomelanin and similar to the spectrum of eumelanin. We could detect Raman signal of both eumelanin and pheomelanin in feathers and hairs where both pigments simultaneously occur without the need of isolating the pigment. This indicates that Raman spectroscopy represents a non-invasive method to detect pheomelanin and distinguish it from other pigments. This may be especially relevant to detect pheomelanin in animal skin including humans, where it has been associated with animal appearance and classification, human phototypes, prevention of skin diseases and cancer risk. PMID:23563634

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

2013-03-13

355

Vibrational characterization of pheomelanin and trichochrome F by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We characterize for the first time the vibrational state of natural pheomelanin using Raman spectroscopy and model pigment synthesized from 5-S-cysteinyldopa. The shape of the Raman spectrum was very different from that of eumelanin. Four Raman bands were visible in the 500-2000 cm-1 wavenumber region about 500, 1150, 1490 and 2000 cm-1, which we assigned to the out-of-plane deformation and the stretching vibration of the phenyl rings, to the stretching vibration of C-N bonds or the stretching and wagging vibration of CH2, and to overtone or combination bands. Interestingly, we also show that the Raman spectrum of synthetic trichochrome F, a pigment that may be produced along with pheomelanin during pheomelanogenesis, is different from that of pheomelanin and similar to the spectrum of eumelanin. We could detect Raman signal of both eumelanin and pheomelanin in feathers and hairs where both pigments simultaneously occur without the need of isolating the pigment. This indicates that Raman spectroscopy represents a non-invasive method to detect pheomelanin and distinguish it from other pigments. This may be especially relevant to detect pheomelanin in animal skin including humans, where it has been associated with animal appearance and classification, human phototypes, prevention of skin diseases and cancer risk.

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

2013-06-01

356

Classification of colonic tissues using Raman spectroscopy and multivariate techniques  

NASA Astrophysics Data System (ADS)

The purpose of this study was to explore the feasibility of using near-infrared (NIR) Raman spectroscopy and multivariate techniques for distinguishing cancer from normal and benign tissue in the colon. A total of 105 colonic specimens were used for Raman studies including 41 normal, 18 polyps, and 46 malignant tumors. The multivariate statistical techniques such as PCA-SVM were utilized to extract the significant Raman features and to develop effective diagnostic algorithms for tissue classification. The results showed that high-quality Raman spectra in the 800-1800 cm-1 range can be acquired from human colonic tissues in vitro, and Raman spectra differed significantly between normal, benign and malignant tumor tissue. PCA-SVM yielded a diagnostic sensitivity of 100%, 100%, and 97.7%, and specificity of 99.8%, 100%, and 100%, respectively, for differentiation between normal, polyp, and malignant tissue. Therefore, NIR Raman spectroscopy associated with multivariate techniques provides a significant potential for the noninvasive diagnosis of colonic cancers in vivo based on optical evaluation of biomolecules.

Huang, Zhiwei; Zheng, Wei; Widjaja, Effendi; Mo, Jianhua; Sheppard, Colin

2006-03-01

357

Raman spectroscopy of garnet-group minerals  

USGS Publications Warehouse

The Raman spectra of the natural end members of the garnet-group minerals, which include pyrope, almandine and spessarite of Fe-Al garnet series and grossularite, andradite and uvarovite of Ca-Fe garnet series, have been studied. Measured Raman spectra of these minerals are reasonably and qualitatively assigned to the internal modes, translational and rotatory modes of SiO4 tetrahedra, as well as the translational motion of bivalent cations in the X site. The stretch and rotatory Alg modes for the Fe-Al garnet series show obvious Raman shifts as compared with those for the Ca-Fe garnet series, owing to the cations residing in the X site connected with SiO4 tetrahedra by sharing the two edges. The Raman shifts of all members within either of the series are attributed mainly to the properties of cations in the X site for the Fe-Al garnet series and in the Y site for the Ca-Fe garnet series. ?? 1994 Institute of Geochemistry, Chinese Academy of Sciences.

Mingsheng, P.; Mao, H. K.; Dien, L.; Chao, E. C. T.

1994-01-01

358

Selection rule for Raman spectroscopy at graphene edge  

NASA Astrophysics Data System (ADS)

The optical matrix element may depend on position in graphene since an electronic wave function is position dependent. In particular, the matrix element near the edges of graphene can differ greatly from that in the bulk. We are pursuing our studies on this point in relation to Raman spectroscopy. We found a selection rule for the G band near the edges of graphene: the intensity is enhanced when the polarization of incident laser is parallel (perpendicular) to the armchair (zigzag) edge [1]. This asymmetry between the armchair and zigzag edges is useful in identifying the orientation of the edge of graphene. Some application of the selection rule is mentioned. We have extended our study to the polarization dependences of the D and 2D (G') bands [2]. The D and 2D bands have different selection rules at bulk and edge. At bulk, the 2D band intensity is maximum when the polarization of the scattered light is parallel to that of incident light, whereas the D band intensity does not have a polarization dependence. At edge, the 2D and D bands exhibit a selection rule similar to that of the G band.[4pt] [1] Sasaki et al., J. Phys. Soc. Jpn. 79, 044603 (2010).[0pt] [2] Sasaki et al., Phys. Rev. B 82, 205407 (2010).

Sasaki, Ken-Ichi; Wakabayashi, Katsunori; Enoki, Toshiaki

2011-03-01

359

Raman spectroscopy and microscopy based on mechanical force detection  

PubMed Central

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.

2011-01-01

360

Raman spectroscopy with graphenated anodized aluminum oxide substrates  

NASA Astrophysics Data System (ADS)

We measured the Raman scattering of graphene deposited nanohole arrays. As the sample was azimuthally rotated, periodicities of 7.5° and 5° were revealed for the 2700 cm-1 and 1600 cm-1 Raman lines of graphene, respectively. This is contrary to the scattered laser line azimuthal symmetry of 30° for the hole array alone. When a reference dye (stilbene) was deposited on the graphenated platforms, its Raman peak shifted as a function of incident (tilt) angle; this was contrary to the unshifted 1600 cm-1 peak of graphene itself. The data suggest strong coupling between the molecular vibrations as portrayed by Raman spectra and surface plasmon polariton waves propagating along the graphene surface.

Banerjee, Amrita; Li, Rui-Qiong; Grebel, Haim

2009-07-01

361

Raman spectroscopy and surface enhanced Raman spectroscopy of catalysts, physiological analytes and cancer drugs  

Microsoft Academic Search

This thesis describes experimental Raman and Surface Enhanced Raman (SERS) studies as well as theoretical Raman calculations of various analytes, designed to gain a greater chemical understanding of their associated systems. Propylene epoxidation gold\\/titania catalysts are examined first. These catalysts are thought to be able to directly convert propylene to propylene oxide in one step, with high selectivity and reactivity.

Penelope Cipriani

2005-01-01

362

Raman fiber laser-pumped 2-?m fiber laser  

NASA Astrophysics Data System (ADS)

We have demonstrated a Tm-Ho-codoped silica fiber laser pumepd by a third-stokes Raman Fiber Laser (RFL) at 1212 nm. RFL consists of Yb-double clad fiber laser (DCFL) as a pump, 1-km Single mode fiber (SMF) and cascated cavities made with fiber Bragg gratings (FBG). For the 30-cm-long Tm-Ho-codoped silica fiber, the output power of 400 mW is obtained at wavelength of 1790 nm (due to the laser radiations of Tm3+ ions). The optical-optical conversion efficiency and the slope efficiency are 18% and 23%, respectively. For the 270-cm-long Tm-Ho-codoped silica fiber, the output power of 450 mW is obtained at 1970 nm; this is the laser emission from Ho3+ ions. The optical efficiency is 18% and the slope efficiency is measured to be 31%. This is the highest output power ever reported for a Tm-Ho-codoped silica fiber laser.

Taniguchi, Atsushi; Kuwayama, Tetsuro; Shirakawa, Akira; Musha, Mitsuru; Ueda, Ken-ichi; Prabhu, Mahendra

2003-10-01

363

Tunable ring resonators for silicon Raman laser and amplifier applications  

Microsoft Academic Search

Recently, low threshold Raman silicon lasers based on ring resonator architecture have been demonstrated. One of the key elements of the laser cavity is the directional coupler that couples both pump and signal light in and out of the ring resonator from the bus waveguide. The coupling coefficients are crucial for achieving desired laser performance. In this paper, we report

J. K. Doylend; O. Cohen; M. R. Lee; O. Raday; S. Xu; V. Sih; H. Rong; M. Paniccia

2008-01-01

364

Raman spectroscopy of endoliths from Antarctic cold desert environments.  

PubMed

Six endolithic communities from Antarctic cold desert environments have been analysed by Raman spectroscopy. The extreme conditions that the organisms have to withstand in cold environments leads to the adoption of different survival strategies and adaptation of the geological environment. Production of radiation- and desiccation-protective biomolecules is identifiable but the displacement of potentially protective minerals onto the rock surface has also been detected as a protective mechanism against UV-radiation. In this work, Raman spectroscopy is demonstrated as a valuable technique to determine the organic and inorganic compounds used by microorganisms as protective mechanisms against extreme stress conditions. The data from this study will be useful for construction of molecular recognition biomarkers and remote Raman spectral sensing experiments proposed for terrestrial extremophiles in stressed environments. PMID:15665968

Villar, Susana E Jorge; Edwards, Howell G M; Cockell, Charles S

2004-12-07

365

Direct characterization of nanocrystal size distribution using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We report a rigorous analytical approach based on one-particle phonon confinement model to realize direct detection of nanocrystal size distribution and volume fraction by using Raman spectroscopy. For the analysis, we first project the analytical confinement model onto a generic distribution function, and then use this as a fitting function to extract the required parameters from the Raman spectra, i.e., mean size and skewness, to plot the nanocrystal size distribution. Size distributions for silicon nanocrystals are determined by using the analytical confinement model agree well with the one-particle phonon confinement model, and with the results obtained from electron microscopy and photoluminescence spectroscopy. The approach we propose is generally applicable to all nanocrystal systems, which exhibit size-dependent shifts in the Raman spectrum as a result of phonon confinement.

Do?an, ?lker; van de Sanden, Mauritius C. M.

2013-10-01

366

Principle, system, and applications of tip-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is a powerful technique in chemical information characterization. However, this spectral method is subject to two obstacles in nano-material detection. One is diffraction limited spatial resolution, and the other is its inherent small Raman cross section and weak signaling. To resolve these problems, a new approach has been developed, denoted as tip-enhanced Raman spectroscopy (TERS). TERS is capable of high-resolution and high-sensitivity detection and demonstrated to be a promising spectroscopic and micro-topographic method to characterize nano-materials and nanostructures. In this paper, the principle and experimental system of TERS are discussed. The latest application of TERS in molecule detection, biological specimen identification, nanao-material characterization, and semi-conductor material determination with some specific experimental examples are presented.

Zhang, MingQian; Wang, Rui; Wu, XiaoBin; Wang, Jia

2012-08-01

367

Shell-isolated nanoparticle-enhanced Raman spectroscopy  

Microsoft Academic Search

Surface-enhanced Raman scattering (SERS) is a powerful spectroscopy technique that can provide non-destructive and ultra-sensitive characterization down to single molecular level, comparable to single-molecule fluorescence spectroscopy. However, generally substrates based on metals such as Ag, Au and Cu, either with roughened surfaces or in the form of nanoparticles, are required to realise a substantial SERS effect, and this has severely

Jian Feng Li; Yi Fan Huang; Yong Ding; Zhi Lin Yang; Song Bo Li; Xiao Shun Zhou; Feng Ru Fan; Wei Zhang; Zhi You Zhou; De Yin Wu; Bin Ren; Zhong Lin Wang; Zhong Qun Tian

2010-01-01

368

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

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

369

Micro-Raman spectroscopy in the undergraduate research laboratory  

Microsoft Academic Search

Modern materials science requires processing and characterization techniques for microscopic structures. Molecular probes such as Raman spectroscopy are some of the most viable tools, particularly if they are supplemented by imaging to obtain spatially resolved compositional information of inhomogeneous or low volume samples. In order to introduce these techniques and materials science experiments into the advanced undergraduate laboratory, we have

R. Voor; L. Chow; A. Schulte

1994-01-01

370

Detection of hazardous chemicals using field-portable Raman spectroscopy  

Microsoft Academic Search

A major challenge confronting emergency response, border control, and other security-related functions is the accurate, rapid, and safe identification of potentially hazardous chemicals outside a laboratory environment. Raman spectroscopy is a rapid, non-intrusive technique that can be used to confidently identify many classes of hazardous and potentially explosive compounds based on molecular vibration information. Advances in instrumentation now allow reliable

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

2003-01-01

371

Probing charged impurities in suspended graphene using Raman spectroscopy  

Microsoft Academic Search

Charged impurity (CI) scattering is one of the dominant factors that affect the carrier mobility in graphene. In this paper, we use Raman spectroscopy to probe the charged impurities in suspended graphene. We find that the 2D band intensity is very sensitive to the CI concentration in graphene, while the G band intensity is not affected. The intensity ratio between

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

2008-01-01

372

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

373

Online quality control with Raman spectroscopy in pharmaceutical tablet manufacturing  

Microsoft Academic Search

Quality testing for tablet composition and uniformity at the manufacturing stage is critical to the pharmaceutical industry. However, current off-line, destructive, wet chemistry analysis incurs significant costs and long test times. This paper introduces a methodology to form a population batch size for quality control sampling in tablet manufacturing for an alternative online testing technology, Raman spectroscopy. An approach is

Julie Ann Stuart Williams; Winston Bonawi-Tan

2004-01-01

374

High performance Raman spectroscopy with simple optical components  

Microsoft Academic Search

Several simple experimental setups for the observation of Raman scattering in liquids and gases are described. Typically these setups do not involve more than a small (portable) CCD-based spectrometer (without scanning), two lenses, and a portable laser. A few extensions include an inexpensive beam-splitter and a color filter. We avoid the use of notch filters in all of the setups.

W. R. C. Somerville; E. C. Le Ru; P. T. Northcote; P. G. Etchegoin

2010-01-01

375

The Discrimination of Colored Acrylic, Cotton, and Wool Textile Fibers Using Micro-Raman Spectroscopy. Part 1: In situ Detection and Characterization of Dyes.  

PubMed

Raman spectroscopy has been applied to characterize fiber dyes and determine the discriminating ability of the method. Black, blue, and red acrylic, cotton, and wool samples were analyzed. Four excitation sources were used to obtain complementary responses in the case of fluorescent samples. Fibers that did not provide informative spectra using a given laser were usually detected using another wavelength. For any colored acrylic, the 633-nm laser did not provide Raman information. The 514-nm laser provided the highest discrimination for blue and black cotton, but half of the blue cottons produced noninformative spectra. The 830-nm laser exhibited the highest discrimination for red cotton. Both visible lasers provided the highest discrimination for black and blue wool, and NIR lasers produced remarkable separation for red and black wool. This study shows that the discriminating ability of Raman spectroscopy depends on the fiber type, color, and the laser wavelength. PMID:24147967

Buzzini, Patrick; Massonnet, Genevieve

2013-10-22

376

Raman spectroscopy of submicron KNO3 films  

Microsoft Academic Search

We have obtained Raman spectra of phase-I, -II, and -III KNO3 films 0.26 mum thick. The primary aim was to establish the physical mechanism for stabilization of the ferroelectric phase III in thin films. In bulk, phase III exists only as a reentrant phase stable from ~113 °C to 120 °C. However, application of hydrostatic or uniaxial pressure greatly enlarges

J. F. Scott; Ming-Sheng Zhang; R. Bruce Godfrey; C. Araujo; L. McMillan

1987-01-01

377

Industrial Raman mapping spectroscopy for mining applications  

NASA Astrophysics Data System (ADS)

A Raman mapping system for detecting and discriminating minerals such as dolomite, marble, calcite and pyrite is demonstrated. The system is built from components that are suitable for industrial conditions. Together with a signal processing and a classier the system was shown to be capable of discriminating between several important classes of mineral. The technique is a potential alternative to sensing methods currently used for mineral sorting.

De Biasio, Martin; Arnold, Thomas; McGunnigle, Gerald; Leitner, Raimund; Tortschanoff, Andreas; Fietz, Nina; Weitkämper, Lars; Balthasar, Dirk; Rehrmann, Volker

2012-05-01

378

Raman Spectroscopy Research of Perovskites Lead Free Ferroelectrics  

NASA Astrophysics Data System (ADS)

Recently, lead-free ferroelectrics have been much of interests as an effective alternative to PZT ceramics for the environmental reasons. Notable progress has been made in chemically modified (K0.5Na0.5)NbO3 (KNN) and (Na0.5Bi0.5)TiO3 (NBT)-based lead-free piezoelectric ceramics, which have high piezoelectricity comparable to PZT ceramics. There are many phases and transitions in lead-free ferroelectrics, for instance, ferrolectric, antiferroelectric which are much to be learned from Raman spectroscopy. Some transitions in lead-free ferroelectrics are not sharp but “diffuse”, or have coexisting phases. Here, there is an introduction to ferroelectricity(FE) and anti-ferroelectricity(AFE). FE is a spontaneous electric polarization of a material that can be reversed by the application of an external electric field or changing temperature. AFE is that materials consist of an ordered array of electric dipoles, but with adjacent dipoles oriented in opposite directions. This can be contrasted with FE, in which the dipoles all point in the same direction. Various spectroscopic techniques have been employed to explore lead-free ferroelectrics, including infrared reflectivity, neutron and x-ray scattering, solid NMR, and Raman scattering, etc. FE type distortions are characterized by unstable or “soft” phonons, whose frequency decreases on approach transition temperature. Raman is effect for exploring soft mode of FE. For example, for BaTiO3, with temperature change, the body centered Ti atom displaced becoming acentric. Relatively, we can see that when Ti atom moves up while O atoms move down. As a result, dipole moment forms below phase transition. Electron cloud of Ti-O bond changes, with respect to vibration of molecule exhibiting Raman effect. In Raman spectroscopy, a change in molecular polarization potential - or amount of deformation of electron cloud - with respect to vibrational coordinate is required for molecule to exhibit Raman effect. Raman intensity reflects polarizability change and Raman shift stands for proportional to vibrational level involved. Thus from Raman, we can learn much about FE and AFE phase transformations. Raman spectroscopy is effect for researching phase transition in perovskites ferroelectrics.

Luo, L.; Ge, W.; Li, J.; Viehland, D.; Farley, C.; Bodnar, R. J.

2009-12-01

379

Stimulated Raman Side Scattering in Laser Wakefield Acceleration  

NASA Astrophysics Data System (ADS)

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.

2010-07-01

380

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

381

Characterisation of Deep Layers of Tissue and Powders: Spatially Offset Raman and Transmission Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

This chapter reviews emerging techniques for deep, non-invasive Raman spectroscopy of diffusely scattering media. As generic analytical tools, these methods pave the way for a host of new applications including non-invasive disease diagnosis, chemical identification and characterisation of pharmaceutical products.

Macleod, N. A.; Morris, M. D.; Matousek, P.

382

Noninvasive, On-Line Monitoring of the Biotransformation by Yeast of Glucose to Ethanol Using Dispersive Raman Spectroscopy and Chemometrics  

Microsoft Academic Search

We describe the ® rst application of dispersive Raman spectroscopy using a diode laser exciting at 780 nm and a charge-coupled device (CCD) detector to the noninvasive, on-line determination of the bio- transformation by yeast of glucose to ethanol. Software was devel- oped which automatically removed the effects of cosmic rays and other noise, normalized the spectra to an invariant

Adrian D. Shaw; Naheed Kaderbhai; Alun Jones; Andrew M. Woodward; Royston Goodacre; Jem J. Rowland; Douglas B. Kell

1999-01-01

383

Combined fluorescence-Raman spectroscopy measurements with an optical fiber probe for the diagnosis of melanocytic lesions  

NASA Astrophysics Data System (ADS)

We have designed and developed an optical fiber-probe for spectroscopic measurements on human tissues. The experimental setup combines fluorescence spectroscopy and Raman spectroscopy in a multidimensional approach. Concerning fluorescence spectroscopy, the excitation is provided by two laser diodes, one emitting in the UV (378 nm) and the other emitting in the visible (445 nm). These two lasers are used to selectively excite fluorescence from NADH and FAD, which are among the brightest endogenous fluorophores in human tissues. For Raman and NIR spectroscopy, the excitation is provided by a third laser diode with 785 nm excitation wavelength. Laser light is delivered to the tissue through the central optical fiber of a fiber bundle. The surrounding 48 fibers of the bundle are used for collecting fluorescence and Raman and for delivering light to the spectrograph. Fluorescence and Raman spectra are acquired on a cooled CCD camera. The instrument has been tested on fresh human skin biopsies clinically diagnosed as malignant melanoma, melanocytic nevus, or healthy skin, finding an optimal correlation with the subsequent histological exam. In some cases our examination was not in agreement with the clinical observation, but it was with the histological exam, demonstrating that the system can potentially contribute to improve clinical diagnostic capabilities and hence reduce the number of unnecessary biopsies.

Cosci, Alessandro; Cicchi, Riccardo; Rossari, Susanna; De Giorgi, Vincenzo; Massi, Daniela; Pavone, Francesco S.

2012-02-01

384

Tunable ring resonators for silicon Raman laser and amplifier applications  

NASA Astrophysics Data System (ADS)

Recently, low threshold Raman silicon lasers based on ring resonator architecture have been demonstrated. One of the key elements of the laser cavity is the directional coupler that couples both pump and signal light in and out of the ring resonator from the bus waveguide. The coupling coefficients are crucial for achieving desired laser performance. In this paper, we report design, fabrication, and characterization of tunable silicon ring resonators for Raman laser and amplifier applications. By employing a tunable coupler, the coupling coefficients for both pump and signal wavelength can be tailored to their optimal values after the fabrication, which significantly increases the processing tolerance and improves the device performance.

Doylend, J. K.; Cohen, O.; Lee, M. R.; Raday, O.; Xu, S.; Sih, V.; Rong, H.; Paniccia, M.

2008-03-01

385

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

386

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

2010-09-01

387

[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

388

[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

389

Fiber optic sensor for general anesthetics based on Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Vibrational spectroscopy and chemometrics together can be used to identify and quantify low concentrations of small molecules, but the Raman effect has been considered too weak to be employed for remote fiber optic sensing of such gases. Preliminary data are presented suggesting that it is possible to enhance Raman signals of gases from a small probe. Polymers that have large partition coefficients for small nonpolar molecules such as general anesthetics can be used as selective absorbents for these gases. As long as the polymers do not luminesce or Raman scatter at interfering frequencies, they increase the signal-to-noise ratio of signals from absorbed molecules. Multipass cells are often used to enhance Raman scattering from gases. Forming an absorbent polymer into a ring with one or more optical `taps' allows recirculation of the excitation light, and extraction of the contrarotating Raman scattered light. Such a ring could be the basis of a small probe to be connected to a compact Raman instrument by optical fibers. These two methods of amplification improve signal-to-noise ratio, extend sensing range, and reduce both instrumental complexity and cost of sensors.

MacDonald, Hillary L.; Liu, Hao; Yager, Paul

1994-07-01

390

Suppression of Raman-resonant interferences in rotational coherent anti-Stokes Raman spectroscopy using time-delayed picosecond probe pulses.  

PubMed

We measure time-dependent pure-rotational coherent anti-Stokes Raman spectroscopy (CARS) spectra for room-temperature N(2), O(2), CO(2), C(2)H(4), and C(3)H(8), as well as in a C(3)H(8) diffusion flame, using picosecond lasers. Because Raman coherences for N(2) and O(2) persist significantly longer than those for the other species, delayed probing can significantly reduce unwanted resonant contributions to rotational coherent anti-Stokes Raman spectroscopy spectra, enabling temperature and relative O(2)/N(2) concentration determination in fuel-rich gas mixtures. Delayed probing also eliminates interference from smeared vibrational CARS. Probe delay affects both the temperature and relative O(2)/N(2) concentrations inferred from rotational spectra when using a standard frequency-domain analysis. PMID:20548379

Seeger, Thomas; Kiefer, Johannes; Gao, Yi; Patterson, Brian D; Kliewer, Christopher J; Settersten, Thomas B

2010-06-15

391

Laser-Raman radar —Laser-Raman scattering methods for remote detection and analysis of atmospheric pollution  

Microsoft Academic Search

This paper reviews the recent progress of the laser radar method, providing single-ended and range-resolved means for remote detection and analysis of various molecular species in the polluted as well as ordinary atmosphere, based on the existence of their Raman backscattering; simply called the laser-Raman radar method. A brief description is given of the operational principle including the basic concept

H. Inaba; T. Kobayasi

1972-01-01

392

Automated autofluorescence background subtraction algorithm for biomedical Raman spectroscopy.  

PubMed

A significant advantage of Raman spectroscopy as a noninvasive optical technique is its ability to detect subtle molecular or biochemical signatures within tissue. One of the major challenges for biomedical Raman spectroscopy is the removal of intrinsic autofluorescence background signals, which are usually a few orders of magnitude stronger than those arising from Raman scattering. A number of methods have been proposed for fluorescence background removal including excitation wavelength shifting, Fourier transformation, time gating, and simple or modified polynomial fitting. The single polynomial and the modified multi-polynomial fitting methods are relatively simple and effective, and thus are widely used in biological applications. However, their performance in real-time in vivo applications and low signal-to-noise ratio environments is sub-optimal. An improved automated algorithm for fluorescence removal has been developed based on modified multi-polynomial fitting, but with the addition of (1) a peak-removal procedure during the first iteration, and (2) a statistical method to account for signal noise effects. Experimental results demonstrate that this approach improves the automated rejection of the fluorescence background during real-time Raman spectroscopy and for in vivo measurements characterized by low signal-to-noise ratios. PMID:18028702

Zhao, Jianhua; Lui, Harvey; McLean, David I; Zeng, Haishan

2007-11-01

393

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

394

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

395

Research of high power and stable laser in portable Raman spectrometer based on SHINERS technology  

NASA Astrophysics Data System (ADS)

The intensity of Raman light is very weak, which is only from 10-12 to 10-6 of the incident light. In order to obtain the required sensitivity, the traditional Raman spectrometer tends to be heavy weight and large volume, so it is often used as indoor test device. Based on the Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy (SHINERS) method, Raman optical spectrum signal can be enhanced significantly and the portable Raman spectrometer combined with SHINERS method will be widely used in various fields. The laser source must be stable enough and able to output monochromatic narrow band laser with stable power in the portable Raman spectrometer based on the SHINERS method. When the laser is working, the change of temperature can induce wavelength drift, thus the power stability of excitation light will be affected, so we need to strictly control the working temperature of the laser, In order to ensure the stability of laser power and output current, this paper adopts the WLD3343 laser constant current driver chip of Wavelength Electronics company and MCU P89LPC935 to drive LML - 785.0 BF - XX laser diode(LD). Using this scheme, the Raman spectrometer can be small in size and the drive current can be constant. At the same time, we can achieve functions such as slow start, over-current protection, over-voltage protection, etc. Continuous adjustable output can be realized under control, and the requirement of high power output can be satisfied. Max1968 chip is adopted to realize the accurate control of the laser's temperature. In this way, it can meet the demand of miniaturization. In term of temperature control, integral truncation effect of traditional PID algorithm is big, which is easy to cause static difference. Each output of incremental PID algorithm has nothing to do with the current position, and we can control the output coefficients to avoid full dose output and immoderate adjustment, then the speed of balance will be improved observably. Variable integral incremental digital PID algorithm is used in the TEC temperature control system. The experimental results show that comparing with other schemes, the output power of laser in our scheme is more stable and reliable, moreover the peak value is bigger, and the temperature can be precisely controlled in +/-0.1°C, then the volume of the device is smaller. Using this laser equipment, the ideal Raman spectra of materials can be obtained combined with SHINERS technology and spectrometer equipment.

Cui, Yongsheng; Yin, Yu; Wu, Yulin; Ni, Xuxiang; Zhang, Xiuda; Yan, Huimin

2013-08-01

396

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

397

Medical diagnostics with NIR-FT-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The fluorescence of natural constituents of bio-material may conceal its Raman spectra. This fluorescence is reduced by shifting the existing radiation to longer wavelengths. For several reasons the optimum is the excitation with 1064 nm radiation, produced by the Nd:YAG laser. In order to explore the applicability to medical diagnostics we installed an NIR-FT-Raman spectrometer in the 'Universitaetsklinikum Essen'. The results complied within 5 dissertations show that there are some useful potential applications in this field. However, much more work and, especially, international cooperation, is needed to develop this tool further for routine application.

Schrader, Bernhard D.; Dippel, Bernd; Fendel, Sonja; Freis, Regina; Keller, Stefan; Loechte, Thomas; Riedl, Michael; Tatsch, Ellen; Hildebrandt, Peter

1998-04-01

398

Raman spectroscopy on ice cores from Greenland and Antarctica  

NASA Astrophysics Data System (ADS)

Ice cores are invaluable archives for the reconstruction of the climatic history of the earth. Besides the analysis of various climatic processes from isotopes and chemical signatures they offer the unique possibility of directly extracting the past atmosphere from gaseous inclusions in the ice. Many aspects of the formation and alterations of these inclusions, e.g. the entrapment of air at the firn-ice-transition, the formation of crystalline gas hydrates (clathrates) from the bubbles or the structural relaxation during storage of the cores, need to be better understood to enable reliable interpretations of the obtained data. Modern micro Raman spectroscopy is an excellent tool to obtain high-quality data for all of these aspects. It has been productively used for phase identification of solid inclusions [1], investigation of air clathrates [2] and high-resolution measurements of N2/O2 mixing ratios inside individual air bubbles [3,4]. Detailed examples of the various uses of Raman spectroscopy will be presented along with practical information about the techniques required to obtain high-quality spectra. Retrieval and interpretation of quantitative data from the spectra will be explained. Future possibilities for advanced uses of Raman spectroscopy for ice core research will be discussed. [1] T. Sakurai et al., 2009, Direct observation of salts as micro-inclusions in the Greenland GRIP ice core. Journal of Glaciology, 55, 777-783. [2] F. Pauer et al., 1995, Raman spectroscopic study of nitrogen/oxygen ratio in natural ice clathrates in the GRIP ice core. Geophysical Research Letters, 22, 969-971. [3] T. Ikeda-Fukazawa et al., 2001, Variation in N2/O2 ratio of occluded air in Dome Fuji antarctic ice. Journal of Geophysical Research, 106, 17799-17810. [4] C. Weikusat et al., Raman spectroscopy of gaseous inclusions in EDML ice core: First results - microbubbles. Journal of Glaciology, accepted.

Weikusat, C.; Kipfstuhl, S.

2012-04-01

399

1.38-µm mode-locked Raman fiber laser pumped by semiconductor disk laser.  

PubMed

A mode-locked Raman fiber laser pumped by 1.3 µm semiconductor disk laser is demonstrated. Direct Watt-level core-pumping of the single-mode fiber Raman lasers and amplifiers with low-noise disk lasers is demonstrated to represent a highly practical solution as compared with conventional scheme using pumping by Raman wavelength convertors. Raman laser employing passive mode-locking by nonlinear polarization evolution in normal dispersion regime produces stable pedestal-free 1.97 ps pulses at 1.38 µm. Using semiconductor disk lasers capable of producing high power with diffraction-limited beam allows Raman gain to be obtained at virtually any wavelength of interest owing to spectral versatility of semiconductor gain materials and wafer-fusing technology. PMID:21164732

Chamorovskiy, A; Rantamäki, A; Sirbu, A; Mereuta, A; Kapon, E; Okhotnikov, O G

2010-11-01

400

Modern Raman imaging: vibrational spectroscopy on the micrometer and nanometer scales.  

PubMed

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. PMID:23772660

Opilik, Lothar; Schmid, Thomas; Zenobi, Renato

2013-01-01

401

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

402

Fourier-transform laser spectroscopy  

NASA Astrophysics Data System (ADS)

The development of microphotonic sensors based on Fourier-transform laser spectroscopy (FT-LS) is discussed. The application demonstrated is for measurement of vapors from the hydrocarbon fuels JP-8, diesel fuel, and gasoline. The two-laser prototype FT-LS sensor used for our research employs distributed-feedback lasers in the near-infrared spectral region (1.3- and 1.7-?m wavelength). An extension of this research to multilaser arrays is discussed. We believe that this is the first measurement of middle-distillate fuel-vapor concentrations using this optical mixing technique.

McNesby, Kevin L.; Miziolek, Andrzej W.

2003-04-01

403

Development of a biofluid chemical measurement system using liquid core optical fiber Raman spectroscopy  

Microsoft Academic Search

Near Infrared (NIR) Raman spectroscopy can provide compositional information about chemicals dissolved in biological fluids. The Raman intensity is proportional to the amount of chemicals. It has been developed for years as a tool to measure biofluid chemical concentrations by illuminating sample and collecting Raman intensity holding the sample in a cuvette geometry. It has been found that the Raman

Dahu Qi

2006-01-01

404

Raman spectroscopy of single layer graphitic carbon nitride  

NASA Astrophysics Data System (ADS)

Single layer graphitic carbon nitride (referred to as melon) has been synthesized by our group in sizes up to 50 ?m across. Raman spectroscopy has been performed on single layer melon and multi layer samples. Much like graphene, melon shows a unique raman spectrum when in single layer form. These experimental results have been compared to theoretical calculations for possible melon structures. Bond counts for feasible structures of hexagonal carbon nitride have been calculated and some possible structures have been eliminated from consideration based on these efforts. Periodic supercells have been built to make sheets based on structures to be modeled via density-functional theory, as implemented using VASP, to calculate thermodynamic and structural stability and frequencies of IR and Raman active modes.

Therrien, Joel; Li, Yancen; Schmidt, Daniel; Collard, Adam; Finkenstadt, Daniel; Yust, Taylor

2013-03-01

405

Epoxy cure monitoring using fiber-optic Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The curing reaction of an epoxy matrix used for wet-filament-wound composites was monitored using Raman spectroscopy measured over fiber optics. The resin system consists of the diglycidyl ether of bisphenol-A in combination with a polyethertriamine hardener in a 1:1 stoichiometric ratio. A Raman peak associated with a phenyl ring vibration in the epoxide component was used as an internal reference to correct for density changes and instrumental variations. Temperature measurements were made over the same fiber optics used to obtain the cure chemistry data by measuring the intensity of anti-Stokes Raman scattering from the epoxy. Both single-fiber and dual-fiber probes were evaluated.

Myrick, M. L.; Angel, S. M.; Lyon, R. E.; Vess, T. M.

1992-08-01

406

Visible and UV Raman spectroscopy of membrane-bound peptides  

NASA Astrophysics Data System (ADS)

Two Raman spectroscopic methods are presented to investigate the structures of membrane- bound peptides. In the first method, water accessibility to each tryptophan side chain of gramicidin A incorporated into phospholipid liposomes has been measured by use of hydrogen-deuterium exchange, selective isotopic labeling, and visible Raman spectroscopy. The water accessibility data are best explained by a newly proposed ion channel structure of gramicidin A. In the second method, we utilize ultraviolet resonance Raman intensity as a probe of environments of aromatic residues. Application of this method to enkephalin has shown that the tyrosine side chain is buried in the hydrophobic region of the lipid membrane while the phenylalanine side chain is not.

Takeuchi, Hideo; Maruyama, Teruhiko; Ohtsuka, Yoshikazu; Harada, Issei

1993-06-01

407

A Raman Spectroscopy Database of Water Pollutants and the Data Compression  

Microsoft Academic Search

Every substance has its own feature Raman spectroscopy (RS), which intensity is proportional to its concentration under certain condition. This is the basis of Raman spectroscopy to analyze the structure, components, concentrations and some other properties of samples. In order to research how to build up a Raman database of water pollutants, we detected some water pollutants and obtained their

Chen Chen; Peng Fei; Xu Dahai; Cheng Qinghua

2010-01-01

408

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

2013-08-29

409

Raman Spectra of High-? Dielectric Layers Investigated with Micro-Raman Spectroscopy Comparison with Silicon Dioxide  

PubMed Central

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.

Borowicz, P.; Taube, A.; Rzodkiewicz, W.; Latek, M.; Gieraltowska, S.

2013-01-01

410

Characterization of human skin cells for tissue engineering applications by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In the field of cell culture and tissue engineering is an increasing need for non-invasive methods to analyze living cells in vitro. One important application is the cell characterization in tissue engineering products. Raman spectroscopy is a method which analyzes cells without lysis, fixation or the use of any chemicals and do not affect cell vitality adversely if suitable laser powers and wavelength are used. This purely optical technique is based on inelastic scattering of laser photons by molecular vibrations of biopolymers. Basically Raman spectra of cells contain typical fingerprint regions and information about cellular properties. Characteristic peaks in Raman spectra could be assigned to biochemical molecules like proteins, nucleic acid or lipids. The distinction of cell types by a multivariate analysis of Raman spectra is possible due to their biochemical differences. As this method allows a characterization of cells without any cell damage it is a promising technology for the quality control of cells in tissue engineering or cell culture applications.

Pudlas, Marieke; Koch, Steffen; Bolwien, Carsten; Walles, Heike

2010-02-01

411

In vivo measurement of the carotenoid level using portable resonance Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Carotenoid is an important antioxidant in human body, which can eliminate the free radicals and other harmful reactive oxygen species. The standard technique for measuring carotenoid is high-pressure liquid chromatography which involves using chemicals and is invasive. In this paper, we present a portable resonance Raman spectroscopy system for measuring carotenoid in vivo, which is noninvasive, highly sensitive and compact. A small diode-pumped all solid-state 473nm laser instead of a 488nm Argon ion laser is used to excite in vivo the carotenoid in the thumb, and the resonance Raman scattering light intensity is measured to assess the carotenoid level. Basically, it is difficult to detect the very weak resonance Raman scattering light because it is overlapping with the strong fluorescence. Our investigation shows that matching glycerol can help to reduce tissue scattering and increase light collecting efficiency. We demonstrate that the employment of optical matching technology for measuring carotenoid resonance Raman spectra in tissue can improve the signal-to-noise ratio by 3.9dB.

Shao, Yonghong; Qu, Junle; He, Yonghong

2007-07-01

412

Doppler Free Laser Spectroscopy  

NSDL National Science Digital Library

In this experiment you will use a technique known as saturation-absorption spectroscopy to study the hyperfine structure (hfs) of rubidium. This particular method is designed to overcome the limitations imposed by the Doppler-broadening of spectral lines while avoiding the need to work at low temperatures.

2012-01-09

413

Chemical imaging on the nanoscale-top-illumination tip-enhanced Raman spectroscopy.  

PubMed

A top illumination system for tip-enhanced Raman spectroscopy (TERS) in a gap-mode configuration is presented here, which allows chemical analysis of sample surfaces with a lateral resolution beyond the optical diffraction limit and optical detection of very small amounts of analyte molecules (down to single molecule sensitivity). The technique combines the high resolution of an STM with label-free, chemical-rich information of Raman spectra at ambient pressure. In this system, using a special geometry with illumination and detection perpendicular to the sample surface, a lateral resolution of <15 nm was achieved using low laser powers and split second acquisition times per spectrum. This was achieved due to a very high enhancement of the Raman signals in the order of 10(7) by etched metal tips, and allowed the acquisition of 64 x 64 to 200 x 200 pixels chemical Raman maps with full spectral information in every pixel within a reasonable time frame (<25 min for 64 x 64 pixels). The Raman maps give simultaneous information about localization and chemical nature of a sample with high sensitivity and high resolution. PMID:21678769

Stadler, Johannes; Schmid, Thomas; Zenobi, Renato

2011-01-01

414

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

415

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

416

Tunable Diode Laser Spectroscopy.  

NASA Astrophysics Data System (ADS)

Available from UMI in association with The British Library. Requires signed TDF. This thesis presents the results of the first laser study of the 6p_{1/2} to 6p_{3/2} transition in thallium at 1.28 mum. The work includes direct observation of absorption and Faraday rotation spectra and the comparison of these spectra with theoretical predictions. These experiments are the first of a series, the final aim of which is to study and measure the parity violating (PV) optical rotation which is predicted by the Glashow-Weinberg-Salam theory of the electroweak interaction. The impetus to study thallium comes from the high accuracy claimed for the atomic calculations which link the electroweak theory to the magnitude of the optical effect; the rotation at 1.28 ?m is predicted to have a peak value of 1.7 times 10 ^{-7} radians per absorption length of vapour. The laser used in all of the experiments described is an InGaAsP semiconductor laser, which operates on several modes simultaneously. The amplitude noise on an individual mode, coupled with the noise from the germanium photodetectors used, limited the signal-to-noise ratio that could be obtained. It was also observed that the absorption and Faraday rotation effects of the transition produce spectra, the form of which cannot be described correctly without including the particular characteristics of the particular diode laser used. A model for the spectra incorporating the laser characteristics is constructed which accounts for many of the observed features of the data. In particular, the analysis shows that the characteristics of the laser, notably the linewidth of the mode of interest and the satellite modes, which occur on either side of the central mode, vary significantly over the wavelength region of the transition. The analysis is made complicated by this but the values of the atomic and the line broadening parameters which are deduced are consistent with the theoretically predicted values. In a further series of experiments the geometry of the optical polarimeter was varied to optimise the signal -to-noise ratio. A final static resolution of 3 muradians for one absorption length was observed. This is a factor of 20 above the resolution at which we expect to observe PV rotations. Further developments in laser technology at this wavelength coupled with the suggested improvements in the design of the experiment discussed in the thesis should enable the necessary level of resolution to be reached in the near future.

Deeny, J. A.

417

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.

Stockel, S.; Schumacher, W.; Meisel, S.; Elschner, M.; Rosch, P.; Popp, J.

2010-01-01

418

Raman spectroscopy-compatible inactivation method for pathogenic endospores.  

PubMed

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

2010-03-05

419

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

2011-06-01

420

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

421

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

422

In vivo infrared and Raman spectroscopy of human stratum corneum  

NASA Astrophysics Data System (ADS)

ATR-FTIR spectroscopy and Raman spectroscopy were employed to obtain information about the molecular composition and hydration of skin in vivo. Both techniques enable the in vivo acquisition of high quality spectra within 10-30s at a spectral resolution of 8cm-1. The penetration depth of ATR-FTIR is about 1.5 (Mu) m. Raman spectra could be obtained with a resolution of about 5 micrometers . ATR-FTIR spectra of hydrated stratum corneum were analyzed using a band fitting algorithm. By means of this algorithm the signal contributions of water relative to protein signal contributions could be determined. The results of Raman microspectroscopic experiments on frozen sections and isolated skin components were used for the interpretation of Raman spectra obtained in vivo. Information was obtained about lipid components present in the stratum corneum. These were shown to vary widely between individuals and between different locations on the body. The combination of these spectroscopic techniques may prove to be valuable for applications in dermatology and skin care.

Lucassen, Gerald W.; Caspers, Peter J.; Puppels, Gerwin J.

1998-04-01

423

Remote Continuous Wave and Pulsed Laser Raman Detection of Chemical Warfare Agents Simulants and Toxic Industrial Compounds  

Microsoft Academic Search

This study describes the design, assembly, testing and comparison of two Remote Raman Spectroscopy (RRS) systems intended\\u000a for standoff detection of hazardous chemical liquids. Raman spectra of Chemical Warfare Agents Simulants (CWAS) and Toxic\\u000a Industrial Compounds (TIC) were measured in the laboratory at a 6.6 m source-target distance using continuous wave (CW) laser\\u000a detection. Standoff distances for pulsed measurements were 35 m

William Ortiz-Rivera; Leonardo C. Pacheco-Londoño; Samuel P. Hernández-Rivera

2010-01-01

424

Transcutaneous Raman spectroscopy of bone global sampling and ring/disk fiber optic probes  

NASA Astrophysics Data System (ADS)

We have used fiber optic probes with global illumination/collection (PhAT probe, Kaiser Optical Systems) and ring illumination/disk collection configurations for transcutaneous Raman spectroscopy of bone tissue. Both illumination/collection schemes can be used for recovery of spectra of subsurface components. In this paper the global illumination configuration provides minimum local power density and so minimizes the probability of damage to specimens, animals or human subjects. It also allows non-destructive subsurface mapping under certain conditions. The ring/disk probe utilizes a ring of laser light and collects Raman scatter from within the diameter of the ring. This design distributes the laser power for efficient heat dissipation and provides a better collection ratio of subsurface to surface components than the global illumination design. For non-invasive tissue spectroscopy the ring/disk design also provides better rejection of fluorescence from melanocytes. We have tested the performance of these Raman probes on polymer model systems and chicken tibiae.

Schulmerich, Matthew V.; Morris, Michael D.; Vanasse, Thomas M.; Goldstein, Steven A.

2007-03-01

425

Exploitation of resonance Raman spectroscopy as a remote chemical sensor  

SciTech Connect

We have discussed recent experimental results using a resonance-Raman-based LIDAR system as a remote chemical sensor. This spectroscopy has the fundamental advantage that it is based on optical fingerprints that are insensitive to environmental perturbations. By taking advantage of resonance enhancement, which 6 orders-of-magnitude, can be as large as 4 to an increased sensing range for a given chemical concentration or lower detection limit for a given stand-off distance can be realized. The success discussed above can in part be traced back to the use of new state-of-the-art technologies which, only recently, have allowed the phenomenon of resonance-enhanced Raman spectroscopy to be fully exploited as a remote chemical sensor platform. Since many chemicals have electronic transitions in the UV/IS, it is expected that many will have pronounced resonance enhancements.

Sedlacek, A.J.; Chen, C.L.

1995-08-01

426

Raman and Photoluminescence Spectroscopy Studies On Porous Silicon Nanostructures  

NASA Astrophysics Data System (ADS)

In this work, the study of photoluminescence (PL) and Raman spectroscopy of porous silicon nanostructures (NPSi) have been carried out. The samples were prepared by photo-electrochemical anodization method using p-type silicon wafer based. Photoluminescence measurement of NPSi shows increase of PL intensity and blue shift with increasing of etching time. The varies etching time from 20 min to 40 min produced PL emission at a range of 550-800 nm which is in the range of visible PL band. While Raman Spectroscopy measurement shows the spectra were asymmetry and broaden when etching time increase from 20 min to 40 min [Fig.2]. It may due to lattice mismatch strain and part of distortion when porous layer form with increasing the etching time. The photon energy and full half width maximum (FWHM) measurement were carried out to study the optical properties of NPSi which can be used to study the quantum confinement effect.

Asli, N. A.; Yusop, S. F. M.; Rusop, M.; Abdullah, S.

2011-05-01

427

Quantitative Raman Spectroscopy of Biomaterials for Arthroplastic Applications  

NASA Astrophysics Data System (ADS)

Raman microprobe spectroscopy has considerable potential as an analytical tool in orthopedic science for its capability of non-destructively assessing the physical, chemical, and mechanical characteristics of load-bearing parts in arthroplastic components (i.e., artificial joints). In comparison to other assessment techniques, Raman spectroscopy offers high spatial resolution in the characterization of oxidation states, phase transformations, crystallographic textures, and residual stress/strain fields as developed at load-bearing surfaces of arthroplastic components, when embedded in biological environment. Furthermore, confocal probes can be used for non-destructively determining highly graded properties along the material subsurface. We show in this chapter a quantitative visualization of biomaterial mesostructures and, through such information, how the surfaces of orthopedic prostheses react to load bearing in biological environment.

Pezzotti, Giuseppe

428

Identification of active fluorescence stained bacteria by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Microorganisms can be found everywhere e.g. in food both as useful ingredients or harmful contaminations causing food spoilage. Therefore, a fast and easy to handle analysis method is needed to detect bacteria in different kinds of samples like meat, juice or air to decide if the sample is contaminated by harmful microorganisms. Conventional identification methods in microbiology require always cultivation and therefore are time consuming. In this contribution we present an analysis approach to identify fluorescence stained bacteria on strain level by means of Raman spectroscopy. The stained bacteria are highlighted and can be localized easier against a complex sample environment e.g. in food. The use of Raman spectroscopy in combination with chemometrical methods allows the identification of single bacteria within minutes.

Krause, Mario; Beyer, Beatrice; Pietsch, Christian; Radt, Benno; Harz, Michaela; Rösch, Petra; Popp, Jürgen

2008-05-01

429

Surface-enhanced Raman spectroscopy applied to food safety.  

PubMed

Surface-enhanced Raman spectroscopy (SERS) is an advanced Raman technique that enhances the vibrational spectrum of molecules adsorbed on or in the vicinity of metal particles and/or surfaces. Because of its readiness, sensitivity, and minimum sample preparation requirements, SERS is being considered as a powerful technique for food inspection. Key aspects of food-safety assurance, spectroscopy methods, and SERS are briefly discussed in an extended introduction of this review. The recent and potential advances in SERS are highlighted in sections that deal with the (a) detection of food-borne pathogenic microorganisms and (b) the detection of food contaminants and adulteration, concentrated specifically on antibiotics, drugs, hormones, melamine, and pesticides. This review provides an outlook of the work done and a perspective on the future directions of SERS as a reliable tool for food-safety assessment. PMID:23297774

Craig, Ana Paula; Franca, Adriana S; Irudayaraj, Joseph

2013-01-07

430

Micro-Raman spectroscopy characterization of selected meteorites  

Microsoft Academic Search

Raman spectroscopy and scanning electron microscopy (SEM–EDS) have been used to determine some mineral components of four meteorites: Allende, ALHA77 182, ALHA78 045 and ALHA81 002. These meteorites are all chondrites and are believed to have undergone some secondary processes: aqueous alterations on the parent body or weathering processes on the Earth. Chondrites are stony meteorites composed of chondrules, spherical

Aleksandra Weselucha-Birczynska; Magdalena ?mudzka

2008-01-01

431

Surface-enhanced Raman spectroscopy of surfactants on silver electrodes  

SciTech Connect

Surface-enhanced Raman spectroscopy (SERS) has been used to study different kinds of surfactants (cationic, anionic, and nonionic surfactants) adsorbed on a roughened Ag electrode. Spectral assignments are made for the SERS spectrum of cetylpyridinium chloride (CPC), and it is shown that the molecule is oriented with its pyridinium ring end-on at the electrode surface at potentials positive to the point of zero charge (pzc) on Ag.

Sun, Soncheng; Birke, R.L.; Lombardi, J.R. (City Univ. of New York, NY (USA))

1990-03-08

432

Probing Charged Impurities in Suspended Graphene Using Raman Spectroscopy  

Microsoft Academic Search

Charged impurity (CI) scattering is one of the dominant factors that affect\\u000athe carrier mobility in graphene. In this paper, we use Raman spectroscopy to\\u000aprobe the charged impurities in suspended graphene. We find that the 2D band\\u000aintensity is very sensitive to the CI concentration in graphene, while the G\\u000aband intensity is not affected. The intensity ratio between

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

2009-01-01

433

Phase characterization of partially stabilized zirconia by raman Spectroscopy  

Microsoft Academic Search

Raman spectroscopy was used to characterize phase transformations and transition temperatures in partially stabilized zirconia containing less than or equal to20 wt% YâOâ. The completeness of the martensitic transition and its thermal hysteresis was followed in samples with less than or equal to4 wt% YâOâ. Between 5 and 12 wt% the spectra indicate a tetragonal modification precipitated in a disordered

C. H. Perry; R. P. Ingel; D. W. Liu

1985-01-01

434

Negative Thermal Expansion Coefficient of Graphene Measured by Raman Spectroscopy  

Microsoft Academic Search

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

Duhee Yoon; Young-Woo Son; Heonsik Cheong

2011-01-01

435

Stable isotope laser spectroscopy  

NASA Astrophysics Data System (ADS)

Recent advances in semiconductor laser technology have produced a reliable lightweight device ideally suited for a spacecraft high resolution molecular spectrometer. Lead-salt tunable diode lasers (TDL) emit in several spectral modes, each with a very narrow linewidth of -0.0003/cm. This spectral resolution is much narrower than typical Doppler broadened molecular linewidths in the mid-IR range. Thus it is possible to detect individual rotational lines within the vibrational band and measure their intensity, which can be used to determine gas concentration. The narrow spectral lines of any impurity gas tend to lie between the narrow lines of the gas of interest. This represents a major advantage over the accepted gas chromatograph mass spectrometer (GCMS) technique for measuring gas concentrations and isotope ratios. The careful and extensive gas purification procedures required to remove impurities for reliable GCMS measurements will not be required for an IR laser gas analysis. The infrared laser gas analysis technique is being developed to measure stable isotopic ratios of gases such as CO2, CH4, N2O, and NH3. This will eventually lead to development of instruments capable of in situ istopic measurements on planets such as Mars. The carbon (C-12, C-13) isotope ratio is indicative of the type of carbon fixation mechanisms (e.g., photosynthesis, respiration) in operation on a planet, while the nitrogen (N-14, N-15) isotope ratio can probably be used to date nitrogen-bearing Martian samples. The absorbance ratio of two adjacent lines of CO2 in the 2300/cm (4.3 micron) region of the spectrum was measured. The precision of the measurement is presently better than 1 percent and significant improvement is anticipated as rapid sweep-integration techniques and computer controlled data acquistion capabilities are incorporated.

Becker, J. F.; Yaldaei, Ramil; McKay, Christopher P.

1989-03-01

436

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 s