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1

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

2

Nonlinear Raman spectroscopy without tunable laser and application to lidar  

NASA Astrophysics Data System (ADS)

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

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

2001-02-01

3

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

4

Laser Raman spectroscopy of some local anesthetics  

NASA Astrophysics Data System (ADS)

The Raman spectra of benzocaine and procaine hydrochlorides in solid phase are reported. From the assigned inversion and torsion modes we have also estimated the corresponding barriers by using the harmonic approximation.

Alcolea, M.; Sigüenza, C.; Santos, M.; Gonzalez-Diaz, P. F.

1986-03-01

5

Picosecond Raman Spectroscopy: A Two Dye Laser Synchronously Pumped Raman System  

NASA Astrophysics Data System (ADS)

Raman spectroscopy is a mature field of science that does not need introduction nor rationalization for its use. The majority of the Raman spectroscopy literature is concerned with C.W. high resolution spectroscopy. The Raman Scattering instruments utilize almost exclusively laser light sources, and lately nanosecond and picosecond data on time resolved spectra have made their entrance into the scientific journals. The difficulty in most of these resonance Raman experiments is that they do not provide any more time dependent information than fluorescence. This is due to the limitation that a single laser, quite often, a dye laser and its second harmonic are the only two frequencies available for excitation and resonance probe of the excited state. In this scenario, a Raman Scattering signal is emitted and detected only during the lifetime of the excited state. As the excited state decays to either the ground state or other transient species which absorb at a different wavelength, the resonance with the probe wavelength disappears at the same rate as the population of the excited state decays. This rate of depopulation is also portrayed in an identical fashion. These systems are therefore drastically limited in their use as means for the measurement of the evolution of a chemical intermediate. An additional interesting aspect is that of the understanding of the process itself which is being studied, namely the majority of the research papers presented do not address the possibility of the data depicting stimulated emission gain rather than Raman Scattering.

Chung, Y. C.; Hopkins, J. B.; Rentzepis, P. M.

1986-11-01

6

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

7

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

8

Analysis of dissolved C2H2 in transformer oils using laser Raman spectroscopy.  

PubMed

We have developed a laser Raman spectroscopy technique for assessing the working conditions of transformers by measuring dissolved C2H2 gas concentrations present in transformer oils. A frequency doubled Q-switched Nd:YAG laser (532 nm) was used as a laser source, and Raman signals at ~1972 cm(-1) originating from C2H2 gas dissolved in oil were detected. The results show that laser Raman spectroscopy is a useful alternative method for detecting transformer faults. PMID:23546252

Somekawa, Toshihiro; Kasaoka, Makoto; Kawachi, Fumio; Nagano, Yoshitomo; Fujita, Masayuki; Izawa, Yasukazu

2013-04-01

9

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

10

Femtosecond laser induced nanostructuring for surface enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

11

Organic semiconductor distributed feedback (DFB) laser as excitation source in Raman spectroscopy.  

PubMed

As an application of organic semiconductor distributed feedback (DFB) lasers we demonstrate their use as excitation sources in Raman spectroscopy. We employed an efficient small molecule blend, a high quality resonator and a novel encapsulation method resulting in an improved laser output power, a reduced laser line width and an enhanced power stability. Based on theses advances, Raman spectroscopy on selected substances was enabled. Raman spectra of sulfur and cadmium sulfide are presented and compared with the ones excited by a helium-neon laser. We also fabricated a spectrally tunable organic semiconductor DFB laser to optimize the Raman signals for a given optical filter configuration. PMID:24514408

Liu, Xin; Stefanou, Panagiotis; Wang, Bohui; Woggon, Thomas; Mappes, Timo; Lemmer, Uli

2013-11-18

12

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

13

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

14

Single-fiber-laser-based wavelength tunable excitation for coherent Raman spectroscopy  

E-print Network

We demonstrate coherent Raman spectroscopy (CRS) using a tunable excitation source based on a single femtosecond fiber laser. The frequency difference between the pump and the Stokes pulses was generated by soliton self-frequency shifting in a...

Su, Jue; Xie, Ruxin; Johnson, Carey K.; Hui, Rongqing

2013-06-01

15

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

E-print Network

We demonstrate a wavelength tunable optical excitation source for coherent Raman scattering (CRS) spectroscopy based on a single femtosecondfiber laser. Electrically controlled wavelength tuning of Stokes optical pulses was achieved with soliton...

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

2011-10-01

16

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

17

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

18

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

NASA Astrophysics Data System (ADS)

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

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

1999-03-01

19

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

NASA Astrophysics Data System (ADS)

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

2011-10-01

20

Raman spectroscopy of lignin  

SciTech Connect

Although in the past visible-laser-excited Raman spectroscopy has been used to study lignin and lignocellulosics, only limited information could be obtained due to poor signal-to-background ratios in the spectra. Laser-induced fluorescence of lignin caused the background which frequently overwhelmed Raman spectral features. However, with the development of FT Raman spectroscopy wherein 1064 nm laser light is used for sample excitation, the fluorescence problem has been eliminated (for most samples) and the time required to obtain a spectrum has been significantly reduced. Lignin related Raman information has been generated through studies that focused on identifying lignin`s Raman contributions, comparing Raman features of native, milled-wood, and enzyme lignins, and studies of lignin-models. In addition to this foundation work, Raman spectroscopy is being used to obtain new information in a number of research programs, e.g. quantification of lignin in wood and pulps, photoyellowing in mechanical pulps, ultrastructure of woody tissues, characterization of chemically modified lignins and lignocellulosics, and studies of mechanical pulp containing papers.

Agarwal, U.P.; Atalla, R.H.; Ralph, S.A. [USDA Forests Service, Madison, WI (United States)

1996-10-01

21

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

Microsoft Academic Search

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

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

2009-01-01

22

Fundamentals of Raman spectroscopy  

E-print Network

-29 m2 Non-resonant Raman spectroscopy: 10-33 m2 Surface Enhanced Raman Scattering: 10-? m2 Surface" non-resonant and resonant Raman cross sections. So: Surface Enhanced Raman Scattering: 10-21 to 1013112012 1 Fundamentals of Raman spectroscopy Part1 Cees Otto Vibrational Spectroscopy IR

Twente, Universiteit

23

Industrial applications of Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In the last two decades, Raman spectroscopy has matured as an important method for the study of molecules and complex molecular systems. This is evident from the number of fine texts and the many review articles which have been published describing theory and applications of Raman spectroscopy over a very broad range of subjects (1-10). Raman spectroscopy is the essential partner to infrared spectroscopy for a complete vibrational analysis of a molecule in structure determinations. From the understanding developed on small molecules, theory was extended to interpret the spectra of larger systems such as polymers, biological molecules, and ordered condensed phases. The contribution of Raman spectroscopy to these areas has been significant. It was the development of commercial lasers in the 1960s which spurred the renewed interest in the Raman technique. But applications were still limited for highly fluorescing or intensely colored systems. In 1986, a breakthrough paper by Hirschfeld and Chase (11) described the use of near-infrared laser excitation and a commercial interferometer-based FT-IR spectrometer to record FT-Raman spectra. Significant advantages included the inherent multiplex, throughput and data processing features of the FT interferometers and the use of a ND:YAG laser (1.064 ?m) which dramatically decreased problems with sample fluorescence and decomposition. A deluge of papers describing applications of FT-Raman spectroscopy can be found in the Journal of Raman Spectroscopy, Spectrochimica Acta (special issues 40A ad 47A), and Applied Spectroscopy since then.

Grasselli, J. G.; Walder, F.; Petty, C.; Kemeny, G.

1993-03-01

24

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

25

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

PubMed

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

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

2015-01-01

26

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

PubMed

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

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

2014-01-01

27

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

28

Raman spectroscopy of iron oxides and (oxy)hydroxides at low laser power and possible applications in environmental magnetic studies  

Microsoft Academic Search

Raman spectroscopy uses the inelastic scattering of electromagnetic radiation by molecules. Monochromatic light of a laser interacts with phonons, the vibrational modes in the crystal lattice. The energy of the scattered light is shifted by the scattering. The shifts in energy yield the Raman spectrum that is specific for each mineral because the phonons are specific for each mineral. In

Monika Hanesch

2009-01-01

29

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

1998-05-01

30

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

SciTech Connect

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

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

2014-07-07

31

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

NASA Astrophysics Data System (ADS)

We report the study of time evolution of chemical changes on the surface of an InAs nanowire (NW) on laser irradiation in different power density regime, using Raman spectroscopy for a time span of 8-16 min. Mixture of metastable oxides like InAsO4, As2O3 are formed upon oxidation, which are reflected as sharp Raman peaks at ˜240-254 and 180-200 cm-1. Evidence of removal of arsenic layer by layer is also observed at higher power density. Position controlled laser induced chemical modification on a nanometer scale, without changing the core of the NW, can be useful for NW based device fabrication.

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

2014-07-01

32

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 31, 677687 (2000)  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 31, 677­687 (2000) Line-by-line imaging of laser based on coherent one-dimensional four-wave mixing (FWM) with hyper-Raman resonances was developed (FWM) spectroscopy,1­3 although it has been known for a long time4 that the cubic susceptibil- ity

Miles, Richard

33

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

Microsoft Academic Search

Pulsed laser induced breakdown spectroscopy (LIBS) and Raman spectroscopy were performed using a novel laboratory setup employing the same Nd:YAG laser emission at 532nm for the analysis of five commercially available pigments collectively known as “ultramarine blue”, a sodium silicate material of either mineral origin or an artificially produced glass. LIBS and Raman spectroscopy have provided information regarding the elemental

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

2009-01-01

34

Concentration measurements of multiple analytes in human sera by near-infrared laser Raman spectroscopy.  

PubMed

Our primary goal in this study is to demonstrate that near-infrared Raman spectroscopy is feasible as a rapid and reagentless analytic method for clinical diagnostics. Raman spectra were collected on human sera by use of a 785-nm excitation laser and a single-stage holographic spectrometer. A partial-least-squares method was used to predict the analyte concentrations of interest. The prediction errors of total protein, albumin, triglyceride, and glucose in human sera ranged from 1.0% to 10%, which are highly acceptable for clinical diagnosis, of their mean physiological levels. For investigating the potential application of near-infrared Raman spectroscopy in screening of therapeutical drugs and substances of abuse the concentrations of acetaminophen, ethanol, and codeine in water solution were measured in the same fashion. The errors of the Raman tests for acetaminophen and ethanol are lower than their toxic levels in human serum, and the sensitivity for detection of codeine fails to reach its toxic level. PMID:18324058

Qu, J Y; Wilson, B C; Suria, D

1999-09-01

35

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

NASA Astrophysics Data System (ADS)

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

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

2015-02-01

36

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

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

37

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

NASA Astrophysics Data System (ADS)

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

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

2001-06-01

38

Imaging with Raman Spectroscopy  

PubMed Central

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

2010-01-01

39

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

40

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

41

Planetary Surface Analysis Using Fast Laser Spectroscopic Techniques: Combined Microscopic Raman, LIBS, and Fluorescence Spectroscopy  

NASA Astrophysics Data System (ADS)

In situ exploration of planetary surfaces has to date required multiple techniques that, when used together, yield important information about their formation histories and evolution. We present a time-resolved laser spectroscopic technique that could potentially collect complementary sets of data providing information on mineral structure, composition, and hydration state. Using a picosecond-scale pulsed laser and a fast time-resolved detector we can simultaneously collect spectra from Raman, Laser Induced Breakdown Spectroscopy (LIBS), and fluorescence emissions that are separated in time due to the unique decay times of each process. The use of a laser with high rep rate (40 KHz) and low pulse energy (1 ?J/pulse) allows us to rapidly collect high signal to noise Raman spectra while minimizing sample damage. Increasing the pulse energy by about an order of magnitude creates a microscopic plasma near the surface and enables the collection of LIBS spectra at an unusually high rep rate and low pulse energy. Simultaneously, broader fluorescence peaks can be detected with lifetimes varying from nanosecond to microsecond. We will present Raman, LIBS, and fluorescence spectra obtained on natural mineral samples such as sulfates, clays, pyroxenes and carbonates that are of interest for Mars mineralogy. We demonstrate this technique using a photocathode-based streak camera detector as well as a newly-developed solid state Single Photon Avalanche Diode (SPAD) sensor array based on Complementary Metal-Oxide Semiconductor (CMOS) technology. We will discuss the impact of system design and detector choice on science return of a potential planetary surface mission, with a specific focus on size, weight, power, and complexity. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA).

Blacksberg, J.; Rossman, G. R.; Maruyama, Y.; Charbon, E.

2011-12-01

42

Quantitative fiber-optic Raman spectroscopy for tissue Raman measurements  

NASA Astrophysics Data System (ADS)

Molecular profiling of tissue using near-infrared (NIR) Raman spectroscopy has shown great promise for in vivo detection and prognostication of cancer. The Raman spectra measured from the tissue generally contain fundamental information about the absolute biomolecular concentrations in tissue and its changes associated with disease transformation. However, producing analogues tissue Raman spectra present a great technical challenge. In this preliminary study, we propose a method to ensure the reproducible tissue Raman measurements and validated with the in vivo Raman spectra (n=150) of inner lip acquired using different laser powers (i.e., 30 and 60 mW). A rapid Raman spectroscopy system coupled with a ball-lens fiber-optic Raman probe was utilized for tissue Raman measurements. The investigational results showed that the variations between the spectra measured with different laser powers are almost negligible, facilitating the quantitative analysis of tissue Raman measurements in vivo.

Duraipandian, Shiyamala; Bergholt, Mads; Zheng, Wei; Huang, Zhiwei

2014-03-01

43

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

44

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

SciTech Connect

The extreme Venus surface temperatures ({approx}740 K) and atmospheric pressures ({approx}93 atm) create a challenging environment for surface missions. Scientific investigations capable of Venus geochemical observations must be completed within hours of landing before the lander will be overcome by the harsh atmosphere. A combined remote Raman - LIBS (Laser Induced Breakdown Spectroscopy) instrument is capable of accomplishing the geochemical science goals without the risks associated with collecting samples and bringing them into the lander. Wiens et al. and Sharma et al. demonstrated that both analytical techniques can be integrated into a single instrument capable of planetary missions. The focus of this paper is to explore the capability to probe geologic samples with Raman - LIBS and demonstrate quantitative analysis under Venus surface conditions. Raman and LIBS are highly complementary analytical techniques capable of detecting both the mineralogical and geochemical composition of Venus surface materials. These techniques have the potential to profoundly increase our knowledge of the Venus surface composition, which is currently limited to geochemical data from Soviet Venera and VEGA landers that collectively suggest a surface composition that is primarily tholeiitic basaltic with some potentially more evolved compositions and, in some locations, K-rich trachyandesite. These landers were not equipped to probe the surface mineralogy as can be accomplished with Raman spectroscopy. Based on the observed compositional differences and recognizing the imprecise nature of the existing data, 15 samples were chosen to constitute a Venus-analog suite for this study, including five basalts, two each of andesites, dacites, and sulfates, and single samples of a foidite, trachyandesite, rhyolite, and basaltic trachyandesite under Venus conditions. LIBS data reduction involved generating a partial least squares (PLS) model with a subset of the rock powder standards to quantitatively determine the major elemental abundance of the remaining samples. PLS analysis suggests that the major element compositions can be determined with root mean square errors ca. 5% (absolute) for SiO{sub 2}, Al{sub 2}O{sub 3}, Fe{sub 2}O{sub 3}(total), MgO, and CaO, and ca. 2% or less for TiO{sub 2}, Cr{sub 2}O{sub 3}, MnO, K{sub 2}O, and Na{sub 2}O. Finally, the Raman experiments have been conducted under supercritical CO{sub 2} involving single-mineral and mixed-mineral samples containing talc, olivine, pyroxenes, feldspars, anhydrite, barite, and siderite. The Raman data have shown that the individual minerals can easily be identified individually or in mixtures.

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

2010-12-13

45

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

SciTech Connect

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

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

2007-01-09

46

Application of laser Raman spectroscopy to isotopic methanes analysis in fusion fuel gas processing systems  

SciTech Connect

This paper reports that to study application o laser Raman spectroscopy for fusion fuel gas analysis by an in situ method, methane (CH{sub 4}) and tritium (T{sub 2}) mixed gases were measured. In the mixed gases, hydrogen isotope exchange reactions were induced by beta decay, and various isotopic hydrogens and methanes were produced. Spectral peaks of {nu}{sub 1} and {nu}{sub 3} bands were detected individually for CH{sub 4} and four tritiated methanes. The {nu}{sub 1} bands between 1700-1900 cm{sup {minus}1} were selected as suitable ones for quantitative analysis. After mixing T{sub 2} and CH{sub 4} gases, while large amounts of tritiated methanes were produced as time lapsed, the equilibrium state was not reached by the time 1000 h had passed. It was presumed that the isotope exchange reactions were very slow compared to mixed gases of just hydrogen isotopes.

Uda, T. (Energy Research Lab., Hitachi Ltd., 1168 Moriyama-cho Hitachi-shi 316 (JP)); Okuno, K.; Naruse, Y. (Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan))

1992-03-01

47

Evidence of laser induced decomposition of triaminotrinitrobenzene from surface enhanced Raman spectroscopy  

Microsoft Academic Search

It is observed that the focused 632 nm laser of the confocal micro-Raman spectrometer decomposes triaminotrinitrobenzene (TATB). The temperature generated in the laser spot determined by measuring the ratio of the intensities of the anti-Stokes to Stokes spectra is too low to cause thermal decomposition. The observed decomposition is suggested to be a result of laser induced electronic excitation. The

F. J. Owens

2011-01-01

48

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

NASA Astrophysics Data System (ADS)

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

Glaus, Reto; Hahn, David W.

2014-10-01

49

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

PubMed

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

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

2013-11-01

50

Laser-induced excited-state ligation changes for nickel tetraphenylporphine monitored by Raman spectroscopy  

SciTech Connect

Metalloporphyrins offer the interesting possibility of undergoing changes in axial ligation associated with the pumping of excited ligand field states via intersystems crossing from initially populated porphyrin ..pi..-..pi..* states. One example is the extremely rapid and efficient photodissociation of the CO adduct of heme proteins, which has been widely exploited in studying the heme-linked protein dynamics of these O/sub 2/-carrying and -activating macromolecules. Nickel porphyrins offer an attractive system for investigation since they are 4-coordinate and low spin in noncoordinating and weakly coordinating solvents but 6-coordinate and high spin in strongly coordinating solvents. Holten and co-workers have shown with transient optical spectroscopy that the accessible excited state (low spin) of the 6-coordinate species rapidly loses its axial ligands, while the excited state of 4-coordinate nickel porphyrin (high spin) becomes ligated, thanks to the hole created in d/sub z /sup 2// orbital. It should therefore be possible to shift the equilibrium between 4- and 6-coordinate species with photons. In this report the authors demonstrate such pumping with CW laser excitation of stationary samples of NiTPP (nickel tetraphenylporphine) in pyridine and piperidine, using resonance Raman (RR) spectroscopy to monitor the ligation changes. The RR spectra also allow assessment of the structural change attendant upon ligation, and they permit identification of a 5-coordinate species in piperidine solution, with a ground state that is probably high spin.

Kim, D.; Spiro, T.G.

1986-04-16

51

Picosecond timescale Raman processes and spectroscopy  

E-print Network

Pure & App!. Chem., Vol. 57, No. 2, pp. 195—200, 1985. Printed in Great Britain. © 1985 IUPAC Picosecond timescale Raman processes and spectroscopy C. K. Johnson, G. A. Dalickas, S. A. Payne and R. M. Hochstrasser Department of Chemistry, University... the Raman spectra obtained from focused with those from unfocused picosecond laser beans (2. This technique allows the detection of transient Raman spectra but does not provide much information about their time dependence. Quite recently a pump—probe Raman...

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

1985-01-01

52

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

NASA Astrophysics Data System (ADS)

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

Zhu, Liangdong; Liu, Weimin; Fang, Chong

2013-08-01

53

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

SciTech Connect

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

Crawford, B.A.

1995-02-24

54

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

55

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

SciTech Connect

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

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

2013-07-14

56

Near-IR Fourier transform Raman spectroscopy in surgery and medicine: guidance system for laser angioplasty  

NASA Astrophysics Data System (ADS)

We have recently demonstrated the efficacy of a near-infrared-Raman fiberoptic sensor for use in laser angioplasty and cardiovascular surgery. A major advantage of the Raman-based system over existing guidance techniques is its fingerprinting capability with improved specificity for detecting atherosclerotic tissues both in-vitro and in-vivo. The use of such a fiberoptic sensor will improve the safety of laser angioplasty by eliminating the current risk of vessel wall perforation. Once developed, the device also will be well suited for in-vivo monitoring and characterization of restenosis after balloon angioplasty and in-vivo study of atheroma progression and regression in animal models.

Nie, Shuming; Ren, Qiushi; Redd, Douglas C. B.; Yu, Nai-Teng

1992-08-01

57

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

NASA Astrophysics Data System (ADS)

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

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

2010-05-01

58

Semiconductor Raman laser  

SciTech Connect

The semiconductor Raman laser has been realized by using a GaP crystal. Pumping is made by a Q-switched YAG laser operating at 1.064 ..mu..m. The round-trip loss in the Fabry-Perot resonator is 2% or less. The Raman scattering from LO phonons stimulates in the <100> direction, while the forward and backward Raman scattering from TO phonons stimulate in the <110> direction. This semiconductor Raman laser is promising as a semiconductor far-infrared radiation source.

Nishizawa, J.; Suto, K.

1980-05-01

59

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

PubMed

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

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

2011-02-01

60

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

NASA Astrophysics Data System (ADS)

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

Li, Xiaozhou; Wang, Qiuyu; Lin, Junxiu

1999-09-01

61

Raman spectroscopy of composites  

SciTech Connect

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

Young, R.J.; Andrews, M.C.; Yang, X.; Huang, Y.L.; Gu, X.; Day, R.J. [UMIST/Univ. of Manchester (United Kingdom). Manchester Materials Science Centre

1994-12-31

62

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

63

In situ high pressure-temperature Raman spectroscopy technique with laser-heated diamond anvil cells  

E-print Network

heating transparent samples using a metallic foil (Pt,Re, or W) as the laser absorber (internal heating Mössbauer spectroscopy (SMS) to study the sound velocities and magnetic hyperfine parameters of 57 Fe

Lin, Jung-Fu "Afu"

64

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

NASA Astrophysics Data System (ADS)

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

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

2013-01-01

65

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

Microsoft Academic Search

Changes in collagen in the wound during the healing process of guinea pig skin following surgical incisions and LTW was evaluated using in vivo, using Raman spectroscopy. Raman spectroscopy provided information regarding the internal structure of the proteins. After the incisions were closed either by suturing or by LTW the ratio of the Raman peaks of the amide III (1247

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

2010-01-01

66

Fiber enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

67

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

68

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

2012-06-01

69

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

70

New developments in Raman spectroscopy  

Microsoft Academic Search

Es wird ein kurzer Überblick über einige neuere instrumentelle und methodische Entwicklungen in der Raman-Spektroskopie gegeben. In der linearen Raman-Spektroskopie wird eine Mikroprobentechnik, die auf der optischen Levitation durch Strahlungsdruck beruht, sowie der oberflächenverstärkte Ramaneffekt (SERS) diskutiert. Weiterhin werden neuere Entwicklungen nichtlinearer Ramanmethoden, wie CARS (Coherent anti-Stokes Raman Spectroscopy) and IDSRS (Ionization Detected Stimulated Raman Spectroscopy) sowie deren Anwendungen in

W. Kiefer

1986-01-01

71

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

PubMed

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

Moros, Javier; Laserna, J Javier

2015-03-01

72

In situ Raman spectroscopy with laser-heated diamond anvil cells  

E-print Network

laser absorber (internal heating furnace) in the DAC. Metal foils of 5­15 mm in thickness with a small.F. Dobrzhinetskaya, editors q 2005 Elsevier B.V. All rights reserved. 413 #12;spectroscopy (SMS) to study the sound

Lin, Jung-Fu "Afu"

73

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2004; 35: 504514  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2004; 35: 504­514 Published online in Wiley Inter by Raman spectroscopy Alian Wang, Karla Kuebler, Bradley Jolliff and Larry A. Haskin Department of Earth--the Mars Microbeam Raman Spectrometer (MMRS).3 We are also developing strategies to use Raman spectroscopy

74

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

NASA Astrophysics Data System (ADS)

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

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

75

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

PubMed

Inkjet ink analysis is the best way to discriminate between printed documents, or even though more difficult, to connect an inkjet printed document with a brand or model of printers. Raman spectroscopy and laser desorption mass spectrometry (LDMS) have been demonstrated as powerful tools for dyes and pigments analysis, which are ink components. The aim of this work is to evaluate the aforementioned techniques for inkjet inks analysis in terms of discriminating power, information quality, and nondestructive capability. So, we investigated 10 different inkjet ink cartridges (primary colors and black), 7 from the HP manufacturer and one each from Epson, Canon and Lexmark. This paper demonstrates the capabilities of three methods: Raman spectroscopy, LDMS and MALDI-MS. Raman spectroscopy, as it is preferable to try the nondestructive approach first, is successfully adapted to the analysis of color printed documents in most cases. For analysis of color inkjet inks by LDMS, we show that a MALDI matrix (9-aminoacridine, 9AA) is needed to desorb and to ionize dyes from most inkjet inks (except Epson inks). Therefore, a method was developed to apply the 9AA MALDI matrix directly onto the piece of paper while avoiding analyte spreading. The obtained mass spectra are very discriminating and lead to information about ink additives and paper compositions. Discrimination of black inkjet printed documents is more difficult because of the common use of carbon black as the principal pigment. We show for the first time the possibility to discriminate between two black-printed documents coming from different, as well as from the same, manufacturers. Mass spectra recorded from black inks in positive ion mode LDMS detect polyethylene glycol polymers which have characteristic mass distributions and end groups. Moreover, software has been developed for rapid and objective comparison of the low mass range of these positive mode LDMS spectra which have characteristic unknown peaks. PMID:22225847

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

2012-06-10

76

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

77

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

78

Monolithic diamond Raman laser.  

PubMed

A monolithic diamond Raman laser is reported. It utilizes a 13-mm radius of curvature lens etched onto the diamond surface and dielectric mirror coatings to form a stable resonator. The performance is compared to that of a monolithic diamond Raman laser operating in a plane-plane cavity. On pumping with a compact Q-switched laser at 532 nm (16 ?J pulse energy; 1.5 ns pulse duration; 10 kHz repetition-rate; M2<1.5), laser action was observed at the first, second, and third Stokes wavelengths (573 nm, 620 nm and 676 nm, respectively) in both cases. For the microlens cavity, a conversion efficiency of 84% was achieved from the pump to the total Raman output power, with a slope efficiency of 88%. This compares to a conversion efficiency of 59% and a slope efficiency of 74% for the plane-plane case. Total Raman output powers of 134 and 96 mW were achieved for the microlens and plane-plane cavities, respectively. PMID:25768149

Reilly, Sean; Savitski, Vasili G; Liu, Hangyu; Gu, Erdan; Dawson, Martin D; Kemp, Alan J

2015-03-15

79

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

E-print Network

Ã? solution interphase can be achieved by surface- vibrational spectroscopy.1h4 Surface Raman spectroscopy-section by several orders of magnitude.5 Surface-enhanced Raman scat- tering (SERS) is one of these mechanismsJOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 713Ã?719 (1998) An In situ Spectroscopic Study

Brolo, Alexandre G.

80

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 30, 637649 (1999)  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 30, 637­649 (1999) Temperature Dependence difference spectroscopy to determine the temperature dependence of all Raman bands of poly(dA­dT) · poly are distinguished by Raman spectroscopy: pre- melting (10

Movileanu, Liviu

81

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

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 1206­1211 Published online 14 May 2007 of the depolarization ratio from photoacoustic Raman spectroscopy Yuanqin Yu, Ke Lin, Xiaoguo Zhou, Hua Wang, Shilin Liu is reported with an improved setup for photoacoustic Raman spectroscopy (PARS). The precise measurement

Liu, Shilin

82

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 945953 (1998)  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 945Ã?953 (1998) Polarized Dispersion Spectroscopy ProbesRaman Planar and Non-Planar Distortions of Ni(II) Porphyrins with Dierent Peripheral of polarized Raman dispersion spectroscopy to identify symmetry-lowering distortions induced by peripheral sub

Shelnutt, John A.

83

Journal of Raman Spectroscopy J. Raman Spectrosc. 2006; 37: 962965  

E-print Network

Journal of Raman Spectroscopy J. Raman Spectrosc. 2006; 37: 962­965 (www is in continuous increase as shown for example by the Journal of Raman Spectroscopy publications (20.interscience.wiley.com) DOI: 10.1002/jrs.1615 Raman Spectroscopy in Art and Archaeology Ludovic BellotGurlet 1

Paris-Sud XI, Université de

84

Journal of Raman Spectroscopy J. Raman Spectrosc. 2004; 35: 739745  

E-print Network

1 Journal of Raman Spectroscopy J. Raman Spectrosc. 2004; 35: 739­745 (www scale. hal-00315905,version1-2Sep2008 Author manuscript, published in "Journal of Raman Spectroscopy Diffraction under synchrotron radiation (XRD) and micro Raman spectroscopy. These analyses were

Paris-Sud XI, Université de

85

Picosecond inverse Raman spectroscopy of liquid crystals  

Microsoft Academic Search

Because of their well-defined polarisation characteristics, lasers are ideal radiation sources for the spectroscopic investigation of molecular orientation and of the re-orientational dynamics of ordered molecular systems. Among the various spectroscopic techniques which may be employed for investigating molecular alignment, Raman spectroscopy enjoys some unique advantages, not least because all molecules display spectroscopic activity in some part of their vibrational

W. Jeremy Jones

1997-01-01

86

A handheld laser scanning confocal reflectance imagingconfocal Raman  

E-print Network

­ 594 (2007). 5. M. Claybourn and M. Ansell, "Using Raman spectroscopy to solve crime: inks, questionedA handheld laser scanning confocal reflectance imaging­confocal Raman microspectroscopy system reflectance microscopy and confocal Raman spectroscopy have shown potential for non-destructive analysis

Maxwell, Bruce D.

87

Fluorescence rejection in Raman spectroscopy using a synchronously pumped, cavity-dumped dye laser and gated photon counting  

Microsoft Academic Search

The application of a picosecond-pulsed laser system, in conjunction with a time-to-amplitude converter, to the suppression of fluorescence noise in Raman spectra is described. Enhancements of 14.6 (Raman signal\\/fluorescence background) and 2.8 (Raman signal\\/fluorescence noise) were obtained for a solution of benzene doped with a fluorophore with lifetime tau f=11.8 ns, while corresponding improvements of 5.5 and 2.0 were observed

J. Howard; N. J. Everall; R. W. Jackson; K. Hutchinson

1986-01-01

88

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

NASA Astrophysics Data System (ADS)

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

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

2009-08-01

89

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

PubMed

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

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

2009-08-01

90

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

Microsoft Academic Search

The changes of Raman spectra from ex-vivo porcine aorta tissues were studied before and after laser tissue welding (LTW). Raman spectra were measured and compared for normal and welded tissues in both tunica adventitial and intimal sides. The vibrational modes at the peak of 1301 cm-1 and the weak shoulder peak of 1264 cm-1 of amide III for the normal

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

2009-01-01

91

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

92

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

E-print Network

be iden- tified based upon the unique narrowband spectroscopic features in the Raman spectrum. Microscopic target within the context of its natural mineral setting. The laser spot can be focused down to a very

Rossman. George R.

93

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

94

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...

95

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

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2008; 39: 593­598 Published online 5 February Wiley & Sons, Ltd. KEYWORDS: coherent Raman spectroscopy; CARS microscopy; focus engineering; chemical interfaces with focus-engineered coherent anti-Stokes Raman scattering microscopy Vishnu Vardhan

Potma, Eric Olaf

96

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 31, 843849 (2000)  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 31, 843­849 (2000) High signal-to-noise detection resonances offers a new approach to Raman spectroscopy. In this case, atomic fil- ters can be used to provide of rotational Raman scattering through refluorescent and dispersive atomic filters Richard B. Miles,1 * Zhen

Miles, Richard

97

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 802818  

E-print Network

: surface-enhanced Raman spectroscopy; Ag colloids; electrochemical SERS; flavonoids; DFT INTRODUCTION in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jrs.1695 Raman and surface-enhanced Raman Received 19 September 2006; Accepted 5 December 2006 The Raman and surface-enhanced Raman spectra (SERS

Lombardi, John R.

98

Blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2002-11-01

99

Raman spectroscopy: the gateway into tomorrow's virology  

Microsoft Academic Search

In the molecular world, researchers act as detectives working hard to unravel the mysteries surrounding cells. One of the researchers' greatest tools in this endeavor has been Raman spectroscopy. Raman spectroscopy is a spectroscopic technique that measures the unique Raman spectra for every type of biological molecule. As such, Raman spectroscopy has the potential to provide scientists with a library

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

2006-01-01

100

Raman spectroscopy of white wines.  

PubMed

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

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

2015-08-15

101

Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

Laser-based combustion diagnostics, such as single-pulse UV Raman spectroscopy and visible Raman spectroscopy, have been successfully applied to optically-accessible rocket-like test articles. If an independent pressure measurement is available, Raman major species concentration measurements can also provide a temperature measurement. However it is desirable to obtain a Raman-derived temperature measurement without the need for simultaneous pressure measurement, especially when chamber pressure may vary spatially. This report describes Raman temperature measurements obtained by exploiting the variation in shape of the H2 Raman spectrum. Hydrogen is advantageous since it is ubiquitous in H2-O2 systems and its Raman spectrum is simpler than for other diatomics. However the influence of high pressure on the H2 Raman spectrum must be investigated. At moderate pressures, well below those of rocket engines, the Raman spectra of O2 and N2 are known to become featureless due to collisional broadening.

Wehrmeyer, Joseph A.

2002-01-01

102

Effect of pulsed laser irradiation on the structure of GeTe films deposited by metal organic chemical vapor deposition: A Raman spectroscopy study  

SciTech Connect

Phase changes between amorphous and crystallized states were induced by laser irradiation with nanosecond pulses in Ge{sub x}Te{sub y} films grown by metal organic chemical vapor deposition. The different phases were obtained by adjusting the pulse energy and could be distinguished by their different optical reflectivities. The corresponding structural changes were studied by Raman spectroscopy, showing marked differences for the two phases. A clear correlation is found between optical reflectivity levels, crystallographic state and the evolution of Ge-Ge, Te-Te, and Ge-Te Raman bands.

Salicio, O.; Wiemer, C.; Fanciulli, M. [CNR-INFM MDM Laboratory, via C. Olivetti 2, 20041 Agrate Brianza (Italy); Gawelda, W.; Siegel, J.; Afonso, C. N. [Laser Processing Group, Instituto de Optica, CSIC, Serrano 121, E-28006 Madrid (Spain); Plausinaitiene, V.; Abrutis, A. [Department of General and Inorganic Chemistry, Faculty of Chemistry, Vilnius University, Naugarduko 24, LT-2006 VU (Lithuania)

2009-02-01

103

Liquid jet waveguide for Raman spectroscopy  

NASA Astrophysics Data System (ADS)

An optofluidic jet waveguide for Raman spectroscopy is reported. In this device a micro-channel is used to produce a high speed liquid stream acting at the same time, as the solution to analyse and as an optical waveguide. The liquid waveguide, exploiting total internal reflection, is able to effectively collect the Raman signal produced by the chemical compound under analysis opportunely excited by means of a laser source. Using a self-aligned configuration, the liquid jet is directly coupled with a multimode optical fiber collecting the Raman signal towards the detection system. The waveguiding nature of a liquid jet enables high Raman signal collection and the device configuration allows strong reduction of the background as no confining walls are used to contain the solution to analyse. The performances of the system have been successfully tested on isopropyl alcohol in water solutions showing a detection limit for this chemical compound of 0.8+/-0.1%.

Persichetti, Gianluca; Testa, Genni; Bernini, Romeo

2014-03-01

104

Determining the Authenticity of Gemstones Using Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

1998-04-01

105

Characterization of Kevlar Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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

Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

2007-01-01

106

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

107

Laser Raman spectroscopy of THF clathrate hydrate in the temperature range 90-300 K  

NASA Astrophysics Data System (ADS)

In situ Raman and Fourier transform infrared (FTIR-NIR) spectroscopic studies on tetrahydrofuran (THF-C 4H 8O) clathrate hydrate (CH) were reported. The Raman results in lattice (64 cm -1), ring breathing and C-H stretching mode regions are in conformity with earlier reports, while the FTIR (NIR) studies in second order mode region were reported for the first time. Comparison of the results indicate that the band assigned to ring breathing mode around 922 cm -1 (in Raman) and corresponding second order mode in NIR around 4295 cm -1 broadens and shifts in enclathrated THF. The ring breathing mode at lower temperatures ( T < 120 K) is highly asymmetric and splits into two and are due to different host-guest interactions at lower temperatures.

Prasad, P. S. R.; Shiva Prasad, K.; Thakur, N. K.

2007-12-01

108

Laser Raman spectroscopy of THF clathrate hydrate in the temperature range 90-300 K.  

PubMed

In situ Raman and Fourier transform infrared (FTIR-NIR) spectroscopic studies on tetrahydrofuran (THF-C(4)H(8)O) clathrate hydrate (CH) were reported. The Raman results in lattice (64 cm(-1)), ring breathing and C-H stretching mode regions are in conformity with earlier reports, while the FTIR (NIR) studies in second order mode region were reported for the first time. Comparison of the results indicate that the band assigned to ring breathing mode around 922 cm(-1) (in Raman) and corresponding second order mode in NIR around 4295 cm(-1) broadens and shifts in enclathrated THF. The ring breathing mode at lower temperatures (T<120 K) is highly asymmetric and splits into two and are due to different host-guest interactions at lower temperatures. PMID:17728176

Prasad, P S R; Shiva Prasad, K; Thakur, N K

2007-12-15

109

Raman spectroscopy in halophile research.  

PubMed

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

Jehli?ka, Jan; Oren, Aharon

2013-01-01

110

Raman spectroscopy in halophile research  

PubMed Central

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

Jehli?ka, Jan; Oren, Aharon

2013-01-01

111

High fidelity nanohole enhanced Raman spectroscopy.  

SciTech Connect

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

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

2009-01-01

112

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

113

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

SciTech Connect

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

Melendres, C. A.

1999-06-28

114

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2002; 33: 955961  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2002; 33: 955­961 Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jrs.934 Bragg resonance-enhanced coherent anti-Stokes Raman-Stokes Raman scattering (CARS) in molecular nitrogen. Cross-correlation measurements, intended to visualize

Miles, Richard

115

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 927931 (1998)  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 29, 927Ã?931 (1998) Resonance Examination of the Two LowestRaman Amide Excited Statespp* Sanford A. Asher,* Zhenhuan Chi and Pusheng Li Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA The UV Raman spectra of N

Asher, Sanford A.

116

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 660672  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 660­672 Published online 12 March 2007 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jrs.1707 Review Raman scattering as a probe nonhysteretic glass transitions (Tg's) that do not age much. Raman scattering has played a pivotal role

Boolchand, Punit

117

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2003; 34: 642650  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2003; 34: 642­650 Published online in Wiley Inter anti-Stokes Raman scattering (CARS) microscopy Eric O. Potma and X. S. Xie Department of Chemistry that often complicates fluorescence microscopy. Spontaneous Raman microscopy has been applied to retrieve

Xie, Xiaoliang Sunney

118

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

NASA Astrophysics Data System (ADS)

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

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

2010-02-01

119

Raman Spectroscopy of Microbial Pigments  

PubMed Central

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

Edwards, Howell G. M.; Oren, Aharon

2014-01-01

120

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 543550  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 543­550 Published online 21 December of the molecule. Raman excitation of rotational wave packets follows, and phasing and dephasing of their components in time create, in a manner analogous to rotational coherence spectroscopy,8,9 rotational

Peinke, Joachim

121

Raman Spectroscopy of Amorphous Carbon  

SciTech Connect

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

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

1998-01-01

122

Raman spectroscopy of Alzheimer's diseased tissue  

NASA Astrophysics Data System (ADS)

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

Sudworth, Caroline D.; Krasner, Neville

2004-07-01

123

Raman spectroscopy of advanced materials.  

PubMed

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

Huong, P V

1996-06-01

124

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

125

Remote Adjustable focus Raman Spectroscopy Probe  

SciTech Connect

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

126

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

127

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

Microsoft Academic Search

The most commonly used blue pigments in medieval manuscripts are azurite and lapis-lazuli. The first one is a copper-based pigment; the coloring compound of the latter is lazurite, a sodium silico?aluminate in a sulfur matrix. Knowledge of the chemical composition of the materials is essential for the study of illuminated manuscripts. In this paper, micro-Raman and LIBS have been used

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

2001-01-01

128

Simultaneous Conoscopic Holography and Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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

Schramm, Harry F.; Kaiser, Bruce

2005-01-01

129

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

Microsoft Academic Search

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

M. G. S. erreira; T. Mourae Silva; A. Catarino; M. Pankuch; C. A. Melendres

1992-01-01

130

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

131

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

NASA Astrophysics Data System (ADS)

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

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

2002-10-01

132

Raman and surface-enhanced Raman spectroscopy of dithiocarbamate fungicides  

Microsoft Academic Search

The Fourier transform Raman and surface-enhanced Raman spectra on silver colloid of the dithiocarbamate fungicides thiram, ziram, metiram, zineb and mancozeb are reported. Surface-enhanced Raman spectroscopy (SERS) affords good quality vibrational spectra of these fungicides at very low aqueous concentrations. A degradation of these fungicides when interacting with the silver surface can be deduced: thiram and metiram are cleaved at

S Sánchez-Cortés; M Vasina; O Francioso; J. V Garc??a-Ramos

1998-01-01

133

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2007; 38: 853858  

E-print Network

can be easily identified in microscopic textile samples by surface-enhanced Raman spectroscopy in ancient and historical textiles by surface-enhanced Raman scattering Marco Leona1 and John R. Lombardi2 1 fragment. Copyright 2007 John Wiley & Sons, Ltd. KEYWORDS: berberine; surface-enhanced Raman scattering

Lombardi, John R.

134

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

135

Raman spectroscopy of bone metastasis  

NASA Astrophysics Data System (ADS)

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

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

2012-02-01

136

Development and deployment of a precision underwater positioning system for in situ laser Raman spectroscopy in the deep ocean  

NASA Astrophysics Data System (ADS)

The field of ocean geochemistry has recently been expanded to include in situ laser Raman spectroscopic measurements in the deep ocean. While this technique has proved to be successful for transparent targets, such as fluids and gases, difficulty exists in using deep submergence vehicle manipulators to position and control the very small laser spot with respect to opaque samples of interest, such as many rocks, minerals, bacterial mats, and seafloor gas hydrates. We have developed, tested, and successfully deployed by remotely operated vehicle (ROV) a precision underwater positioner (PUP) which provides the stability and precision movement required to perform spectroscopic measurements using the Deep Ocean Raman In situ Spectrometer (DORISS) instrument on opaque targets in the deep ocean for geochemical research. The positioner is also adaptable to other sensors, such as electrodes, which require precise control and positioning on the seafloor. PUP is capable of translating the DORISS optical head with a precision of 0.1 mm in three dimensions over a range of at least 15 cm, at depths up to 4000 m, and under the normal range of oceanic conditions (T, P, current velocity). The positioner is controlled, and spectra are obtained, in real time via Ethernet by scientists aboard the surface vessel. This capability has allowed us to acquire high quality Raman spectra of targets such as rocks, shells, and gas hydrates on the seafloor, including the ability to scan the laser spot across a rock surface in sub-millimeter increments to identify the constituent mineral grains. These developments have greatly enhanced the ability to obtain in situ Raman spectra on the seafloor from an enormous range of specimens.

White, Sheri N.; Kirkwood, William; Sherman, Alana; Brown, Mark; Henthorn, Richard; Salamy, Karen; Walz, Peter; Peltzer, Edward T.; Brewer, Peter G.

2005-12-01

137

Surface-Enhanced Raman Spectroscopy  

Microsoft Academic Search

Abstract The ability to control the size, shape, and material of a surface has reinvigorated the field of surface-enhanced Raman spectroscopy (SERS). Because excitation of the localized surface plasmon,reso- nance of a nanostructured,surface or nanoparticle lies at the heart of SERS, the ability to reliably control the surface characteristics has taken SERS from an interesting surface phenomenon,to a rapidly de-

Paul L. Stiles; Jon A. Dieringer; Nilam C. Shah; Richard P. Van Duyne

2008-01-01

138

Raman and Photoluminescence Spectroscopy in Mineral Identification  

NASA Astrophysics Data System (ADS)

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

Kuehn, J. W.

2014-06-01

139

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

NASA Astrophysics Data System (ADS)

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

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

2015-03-01

140

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

PubMed

Resonance broadband stimulated Raman spectroscopy of malachite green in ethanol has been performed. With a tuning picosecond visible laser source and a broadband Raman probe, the Raman gain and loss spectra have been measured simultaneously. By scanning the Raman pump across the first absorption band of the molecule, we found that the resonant Raman bands could be only seen when the pump laser tuned in the range of the red edge of the S1?S0 transition. Dispersive lineshapes of resonant Raman bands have been observed in the Raman loss spectra, while the line shape is normal (same as spontaneous Raman) in the Raman gain spectra. Although, the resonant bands in the loss spectrum are usually stronger than that in the gain spectrum, the band intensities of both loss and gain linearly increase with the pump energy. The relative magnitude of each corresponding resonant band in the Raman loss and gain varies with the pump wavelength. Mode specified Raman excitation profiles have been obtained through broadband stimulated Raman measurement. PMID:25796242

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

2015-03-21

141

Raman accumulator as a fusion laser driver  

DOEpatents

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

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

1982-03-31

142

Raman accumulator as a fusion laser driver  

DOEpatents

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

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

1985-01-01

143

Application of Raman Spectroscopy for Nondestructive Evaluation of Composite Materials  

NASA Technical Reports Server (NTRS)

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

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

2007-01-01

144

Transcutaneous Raman Spectroscopy of Bone  

NASA Astrophysics Data System (ADS)

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

Maher, Jason R.

145

Laser Spectroscopy  

NASA Astrophysics Data System (ADS)

Degenerate gases. Probing vortex pair sizes in the Berezinskii-Kosterlitz-Thouless regime on a two-dimensional lattice of Bose-Einstein condensates / V. Schweikhard ... [et al.]. Interacting Bose-Einstein condensates in random potentials / P. Bouyer ... [et al.]. Towards quantum magnetism with ultracold atoms in optical lattices / I. Bloch -- Precision measurement and fundamental physics. T-violation and the search for a permanent electric dipole moment of the mercury atom / E. N. Fortson -- Quantum information and control I. Quantum information processing and ramsey spectroscopy with trapped ions / C. F. Roos ... [et al.]. Quantum non-demolition counting of photons in a cavity / S. Haroche ... [et al.] -- Ultra-fast control and spectroscopy. Frequency-Comb- assisted mid-infrared spectroscopy / P. de Natale ... [et al.] -- Precision measurement and applications. Precision gravity tests by atom interferometry / G. M. Tino ... [et al.] -- Novel spectroscopic applications. On a variation of the proton-electron mass ratio / W. Ubachs ... [et al.] -- Quantum information and control II. Quantum interface between light and atomic ensembles / H. Krauter ... [et al.] -- Degenerate Fermi gases. An atomic Fermi gas near a P-wave Feshbach resonance / D. S. Jin, J. P. Gaebler and J. T. Stewart. Bragg scattering of correlated atoms from a degenerate Fermi gas / R. J. Ballagh, K. J. Challis and C. W. Gardiner -- Spectroscopy and control of atoms and molecules. Stark and Zeeman deceleration of neutral atoms and molecules / S. D. Hogan ... [et al.]. Generation of coherent, broadband and tunable soft x-ray continuum at the leading edge of the driver laser pulse / A. Jullien ... [et al.]. Controlling neural atoms and photons with optical conveyor belts and ultrathin optical fibers / D. Meschede. W. Alt and A. Rauschenbeutel -- Spectroscopy on the small scale. Wide-field cars-microscopy / C. Heinrich ... [et al.]. Atom nano-optics and nano-lithography / V. I. Balykin ... [et al.] -- Pinhead town talk, public lecture and mountainfilm. The quantum revolution - towards a new generation of supercomputers / R. Blatt -- Cold atoms and molecules I. Ultracold & ultrafast: making and manipulating ultracold molecules with time-dependent laser fields / C. P. Koch ... [et al.]. Bose-Einstein condensates on magnetic film microstructures / M. Singh ... [et al.] -- Cold atoms and molecules II. Ultracold metastable Helium-4 and Helium-3 gases / W. Vassen ... [et al.] -- Single atoms and quantum optics I. Recent progress on the manipulation of single atoms in optical tweezers for quantum computing / A. Browaeys ... [et al.]. Progress in atom chips and the integration of optical microcavities / E. A. Hinds ... [et al.] -- Single atoms and quantum optics II. Quantum optics with single atoms and photons / H. J. Kimble -- Optical atomic clocks. Frequency comparison of Al[symbol] and Hg[symbol] optical standards / T. Rosenband ... [et al.]. Sr optical clock with high stability and accuracy / A. Ludlow ... [et al.].

Hollberg, Leo; Bergquist, James Charles; Kasevich, Mark A.

2008-04-01

146

Raman Spectroscopy of Ocular Tissue  

NASA Astrophysics Data System (ADS)

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

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

147

Raman spectroscopy of graphene edges.  

PubMed

Graphene edges are of particular interest since their orientation determines the electronic properties. Here we present a detailed Raman investigation of graphene flakes with edges oriented at different crystallographic directions. We also develop a real space theory for Raman scattering to analyze the general case of disordered edges. The position, width, and intensity of G and D peaks are studied as a function of the incident light polarization. The D-band is strongest for polarization parallel to the edge and minimum for perpendicular. Raman mapping shows that the D peak is localized in proximity of the edge. For ideal edges, the D peak is zero for zigzag orientation and large for armchair, allowing in principle the use of Raman spectroscopy as a sensitive tool for edge orientation. However, for real samples, the D to G ratio does not always show a significant dependence on edge orientation. Thus, even though edges can appear macroscopically smooth and oriented at well-defined angles, they are not necessarily microscopically ordered. PMID:19290608

Casiraghi, C; Hartschuh, A; Qian, H; Piscanec, S; Georgi, C; Fasoli, A; Novoselov, K S; Basko, D M; Ferrari, A C

2009-04-01

148

Detection limit of imaging Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Multispectral imaging Raman spectroscopy is a novel technique for detecting and identifying explosive residues, e.g. explosives particles which are left on surfaces after handling or manufacturing of explosives. By imaging a suspect surface using the imaging Raman technique, explosives particles at stand-off distances can be identified and displayed using color coding1. In this paper we present an attempt to determine a limit of detection for imaging Raman spectroscopy by analyzing holes of various sizes in aluminum plates filled with four different substances; 2,4-dinitrotoulene (DNT), ammonium nitrate (AN), sulfur, and 2,4,6-trinitrotoulene (TNT). The detection time in the presented experiments has not been optimized, instead more effort has been invested in order to reduce false alarms. The detection system used is equipped with a green second harmonic Nd:YAG laser with an average power of 2 W, a 200 mm telescope and a liquid crystal tunable filter to scan the wavenumbers. The distance to the target was 10 m and the imaged area was 28 mm × 28 mm. The measured multi-spectral data cubes were evaluated using least square fitting to distinguish between DNT, AN,S, TNT and the background. The detection limit has been determined to be sub microgram using the current setup.

Nordberg, Markus; Ceco, Ema; Wallin, Sara; Östmark, Henric

2012-06-01

149

Modeling of Continuous Wave Intracavity Raman Lasers  

Microsoft Academic Search

We present results from a simple numerical model simulating continuous wave (CW) intracavity Raman lasers and intracavity-doubled Raman lasers, which will guide optimization of experimental devices. We show that the laser efficiently converts the incident pump power into the fundamental photons, allowing us to derive simple expressions for the Raman threshold and total efficiency. The model shows that the behavior

David J. Spence; Peter Dekker; Helen M. Pask

2007-01-01

150

Surface enhanced Raman spectroscopy on chip  

Microsoft Academic Search

In this paper we report on an integrated spectrometer device, fabricated in epoxy resist (SU-8) on silicon, designed for Raman spectroscopy and direct coupling to a CCD element. Furthermore a nanostructured surface is prepared on a gold coated silicon chip to enhance the Raman signal. We show examples of low resolution Surface Enhanced Raman Spectra (SERS) recorded with this chip

Jorg Hubner; Thomas Anhøj; Sarah Pedersen; Dan A. Zauner; Anders M. Jorgensen; Gabriella Blagoi; Ivan Talian; Ole Hansen

2008-01-01

151

Chalcogenide microwire based Raman laser  

NASA Astrophysics Data System (ADS)

We present a Raman fiber laser based on a chalcogenide glass microwire. The microwire is pumped in the C-band, and the resulting laser oscillates in the L-band. The power conversion efficiency of the device is ˜17%, and the laser threshold is 23.2 dBm (pulse energy = 4.65 pJ) in peak pump power. By extension, the device can be used for all-optical wavelength conversion of existing laser sources in the useful transmission window of chalcogenide, from the C-band up to a wavelength of ˜10 ?m in the mid-infrared.

Ahmad, Raja; Rochette, Martin

2012-09-01

152

Monolithic integrated Raman silicon laser.  

PubMed

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 linewidth of <100 kHz. This laser architecture allows for on-chip integration with other silicon photonics components to provide a highly integrated and scaleable monolithic device. PMID:19516852

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

2006-07-24

153

Precise measurement of the depolarization ratio from photoacoustic Raman spectroscopy  

Microsoft Academic Search

A new method for the accurate determination of the Raman depolarization ratio is reported with an improved setup for photoacoustic Raman spectroscopy (PARS). The precise measurement is achieved by measuring the dependence of the acoustic signal intensity on the cross-angle between the polarizations of two incident laser beams. We demonstrate this sensitive and simple method with several gaseous molecules,suchasCH4 andH2.Themeasuredresultsofdepolarizationratiosagreewellwiththetheoretical

Yuanqin Yu; Ke Lin; Xiaoguo Zhou; Hua Wang; Shilin Liu; Xingxiao Ma

2007-01-01

154

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

155

(Luminescence and Raman spectroscopy for biological analysis)  

SciTech Connect

The traveler was invited to present a seminar on Immunofluorescence and Raman Fiberoptic Chemical Sensors'' at the Laboratory FOCAL of CEN-FAR, France. The traveler visited the CEN-FAR laboratories involved in laser-based spectroscopy and remote monitors and conducted scientific discussions with research staff at CEN-FAR. The traveler was also invited to present an invited lecture on Advances in Luminescence and Raman Spectroscopy for Chemical and Biological Analysis'' at the Laboratory of Molecular Photophysics and Photochemistry, University of Bordeaux, Talence, France. The traveler visited the laboratories involved in the development of luminescence techniques for the analysis of polyaromatic pollutants and related biomarkers. The traveler conducted discussions on potential research collaboration with scientists at the University of Bordeaux. The traveler was awarded a North atlantic Treaty Organization (NATO) Collaborative Grant to conduct joint research with Professor P. Viallet, head of the Laboratory of Quantitative Microfluorimetry, University of Perpignan. The traveler was involved in experimental luminescence studies of bioindicators of polyaromatic pollutants (DNA adducts, metabolites).

Vo-Dinh, Tuan.

1990-06-14

156

Ionization-type stimulated-Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Ionization techniques of Raman spectroscopy are reviewed. Attention is given to methods based on the competition of processes of multiphoton ionization and stimulated Raman scattering, and the excitation of the vibrational levels of molecules in the case of stimulated Raman scattering with subsequent photoionization and the capture of slow electrons. Particular attention is given to: (1) the two-photon ionization of Na in a beam at wavelengths of 285-286 nm and 1.06 microns; and (2) photoionization spectroscopy using stimulated Raman scattering in benzene involving four-photon ionization through two-photon resonance.

Beterov, I. M.

1986-04-01

157

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

158

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...

159

In vivo Raman spectroscopy of cervix cancers  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

160

Raman-induced Kerr-effect dual-comb spectroscopy  

E-print Network

We report on the first demonstration of nonlinear dual-frequency-comb spectroscopy. In multi-heterodyne femtosecond Raman-induced Kerr-effect spectroscopy, the Raman gain resulting from the coherent excitation of molecular vibrations by a spectrally-narrow pump is imprinted onto the femtosecond laser frequency comb probe spectrum. The birefringence signal induced by the nonlinear interaction of these beams and the sample is heterodyned against a frequency comb local oscillator with a repetition frequency slightly different from that of the comb probe. Such time-domain interference provides multiplex access to the phase and amplitude Raman spectra over a broad spectral bandwidth within a short measurement time. Experimental demonstration, at a spectral resolution of 200 GHz, a measurement time of 293 {\\mu}s and a sensitivity of 10^-6, is given on liquid samples exhibiting a C-H stretch Raman shift.

Ideguchi, Takuro; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2012-01-01

161

Demonstration of a silicon Raman laser  

Microsoft Academic Search

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

Ozdal Boyraz; Bahram Jalali

2004-01-01

162

Using Resonance Raman Spectroscopy To Examine  

E-print Network

Using Resonance Raman Spectroscopy To Examine Vibrational Barriers to Electron Transfer in Figure 1b, for highly exoergic reactions (nested energy surfaces) struc- tural differences enhance to the interpretation of resonance Raman scattering intensities has been used to obtain quantitative vibrational mode

163

High fidelity nanohole enhanced Raman spectroscopy  

Microsoft Academic Search

Surface enhanced Raman spectroscopy (SERS) is a sensitive technique that can even detect single molecules. However, in many SERS applications, the strongly inhomogeneous distribution of intense local fields makes it very difficult for a quantitive assessment of the fidelity, or reproducibility of the signal, which limits the application of SERS. Herein, we report the development of exceptionally high-fidelity hole-enhanced Raman

John T. Bahns; Qiti Guo; S. K. Gray; H. M. Jaeger; L. Chen; J. M. Montgomery

2009-01-01

164

Raman spectroscopy for noninvasive glucose measurements  

E-print Network

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

Enejder, Annika M. K.

165

Raman spectroscopy: Watching a molecule breathe  

NASA Astrophysics Data System (ADS)

Marrying the single-molecule detection ability of surface-enhanced Raman scattering with the extreme time resolution of ultrafast coherent spectroscopy enables the vibrations of a single molecule to be observed.

Piatkowski, Lukasz; Hugall, James T.; van Hulst, Niek F.

2014-08-01

166

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

SciTech Connect

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

Meyer, Matthew W. [Ames Laboratory

2013-03-14

167

[Study on the treatment turquoise using Raman spectroscopy].  

PubMed

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

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

2010-07-01

168

Debris of potassium-magnesium silicate glass generated by femtosecond laser-induced ablation in air: An analysis by near edge X-ray absorption spectroscopy, micro Raman and energy dispersive X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

The redeposited material (debris) resulting from ablation of a potassium-magnesium silicate glass upon scanning femtosecond laser pulse irradiation (130 fs, 800 nm) in air environment is investigated by means of three complementary surface analytical methods. Changes in the electronic band structure of the glass constituent Magnesium (Mg) were identified by X-ray Absorption Near Edge Structure spectroscopy (XANES) using synchrotron radiation. An up-shift of ?0.8 eV of a specific Magnesium K-edge absorption peak in the spectrum of the redeposited material along with a significant change in its leading edge position was detected. In contrast, the surface left after laser ablation exhibits a downshift of the peak position by ?0.9 eV. Both observations may be related to a change of the Mg coordinative state of the laser modified/redeposited glass material. The presence of carbon in the debris is revealed by micro Raman spectroscopy (?-RS) and was confirmed by energy dispersive X-ray spectroscopy (EDX). These observations are attributed to structural changes and chemical reactions taking place during the ablation process.

Grehn, M.; Seuthe, T.; Reinhardt, F.; Höfner, M.; Griga, N.; Eberstein, M.; Bonse, J.

2014-05-01

169

Standoff detection of explosive molecules using nanosecond gated Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

Chung, Jin Hyuk; Cho, Soo Gyeong

2013-06-01

170

Estimating Atomic Sizes with Raman Spectroscopy  

PubMed Central

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

171

Mobile Raman spectroscopy in astrobiology research.  

PubMed

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

Vandenabeele, Peter; Jehli?ka, Jan

2014-12-13

172

MATERIALS AND INTERFACES CHARACTERIZATION BY MICRO-RAMAN SPECTROSCOPY  

Microsoft Academic Search

Several aspects of Raman and micro-Raman spectroscopy are shown and applied for the characterization of semiconductor materials and bi-layers of semiconductor on semiconductor and insulator on semiconductor. As a molecular technique, Raman spectroscopy will inform not only on the nature of elements but also on chemical bonds between atoms. Raman spectroscopy also permits the studies of disordered or amorphous materials.

P. V. HUONG

1991-01-01

173

Emerging technology: applications of Raman spectroscopy for prostate cancer.  

PubMed

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

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

2014-09-01

174

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

175

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

176

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

177

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

178

Multiplex coherent raman spectroscopy detector and method  

DOEpatents

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

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

2004-06-08

179

Multiplex coherent raman spectroscopy detector and method  

NASA Technical Reports Server (NTRS)

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

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

2004-01-01

180

Temporal and spatial resolution in transmission Raman spectroscopy.  

PubMed

Picosecond time-resolved transmission Raman data were acquired for 1 mm thick powder samples of trans-stilbene, and a Monte Carlo model was developed that can successfully model the laser and Raman pulse profiles. Photon migration broadened the incident (approximately 1 ps) probe pulse by two orders of magnitude. As expected from previous studies of Raman photon migration in backscattering mode, the transmitted Raman pulse was broader than the transmitted laser pulse and took longer to propagate through the sample. The late-arriving photons followed tortuous flight paths in excess of 50 mm on traversing the 1 mm sample. The Monte Carlo code was also used to study the spatial resolution (lateral and depth) of steady-state transmission Raman spectroscopy in the diffusion regime by examining the distribution of Raman generation positions as a function of incident beam size, sample thickness, and transport length. It was predicted that the lateral resolution should worsen linearly with sample thickness (typically the resolution was about 50% of the sample thickness), and this is an inevitable consequence of operating in the diffusion regime. The lateral resolution was better at the sample surface (essentially determined by the probe beam diameter or the collection aperture) than for buried objects, but transmission sampling was shown to be biased towards the mid-point of thick samples. Time-resolved transmission experiments should improve the lateral resolution by preferentially detecting snake photons, subject to constraints of signal-to-noise ratio. PMID:20132598

Everall, Neil; Matousek, Pavel; MacLeod, Neil; Ronayne, Kate L; Clark, Ian P

2010-01-01

181

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

PubMed

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

Xu, Jian-Fang; Liu, Guo-Kun

2015-03-01

182

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

SciTech Connect

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

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

2013-10-28

183

Doppler-Shifted Raman Spectroscopy Measures Flows  

NASA Technical Reports Server (NTRS)

Technique for measuring velocity, static pressure, and translational temperature of flowing molecules by use of stimulated Raman spectroscopy demonstrated in supersonic wind tunnel at NASA Langley Research Center. Nonintrusive, accurate wind-tunnel measurements obtained without seeding flows. Optical equipment for vibration-free Raman doppler velocimetry in wind tunnel includes specially designed retrometer that reduces sensitivity of system to vibrations. This capability very valuable in aerodynamic testing and proves useful in wide variety of laboratory, industrial, and engineering applications.

Exton, Reginald J.; Hillard, Mervin E., Jr.; Lempert, Walter R.; Covell, Peter F.; Miller, David S.

1990-01-01

184

Fourier-Transform Raman Spectroscopy Of Biological Assemblies  

NASA Astrophysics Data System (ADS)

Although the successful coupling of Raman scattered near-infrared radiation to a Michelson interferometer has recently created an outburst of intense interest in Fourier-transform (FT) Raman spectrometry," extended applications of the technique to macromolecular assemblies of biochemical and biophysical relevance have not progressed as rapidly as studies directed primarily at more conventional chemical characterizations. Since biological materials sampled with visible laser excitation sources typically emit a dominant fluorescence signal originating either from the intrinsic fluorescence of the molecular scatterer or from unrelenting contaminants, the use of near-infrared Nd:YAG laser excitation offers a convenient approach for avoiding this frequently overwhelming effect. In addition, the FT-Raman instrumentation provides a means of eliminating the deleterious resonance and decomposition effects often observed with the more accessible green and blue laser emissions. However, in choosing the incident near-infrared wavelength at, for example, 1064nm, the Raman scattered intensity decreases by factors of eighteen to forty from the Raman emissions induced by the shorter, visible excitations. Depending upon the experiment, this disadvantage is offset by the throughput and multiplex advantages afforded by the interferometric design. Thus, for most chemical systems, near-infrared FT-Raman spectroscopy, clearly provides a means for obtaining vibrational Raman spectra from samples intractable to the use of visible laser sources. In particular, for neat liquids, dilute solutions or polycrystalline materials, the ability to achieve high quality, reproducible spectra is, with moderate experience and perhaps relatively high laser powers, as straightforward as the conventional methods used to obtain Raman spectra with visible excitation and dispersive monochromators. In using near-infrared FT techniques to determine the Raman spectra of biological samples, one encounters new sets of experimental problems that may entail an initial, relatively steep learning curve. These difficulties originate particularly from the fragility of the weakly scattering aggregate paired with the dilute nature of the biochemical or cellular dispersion. Often, the Raman scattered intensity from these samples can be increased by carefully peileting the biological suspension using ultracentrifugation techniques. Since the overtone region of water, the usual medium for biological samples, absorbs radiation from both the Rayleigh signal at the exciting wavelength of the Nd:YAG laser and the longer wavelength Raman scattering from the sample, reproducible temperature measurements and temperature control become significant concerns. In these cases one appeals to internal temperature calibrations, use of deuterium oxide (D20) as a solvent (since absorptions of the laser exciting wavelength and Raman scattered photons are minimized), manipulation of incident laser spot size and the use of fiber optic bundles to carry the exciting and scattered radiation. In the present discussion we briefly cite some of the experimental approaches we have developed and experiences we have encountered in adapting near-infrared FT-Raman spectroscopy to the more challenging biophysical and biochemical systems amenable to vibrational analysis. We emphasize here the determination of the spectra of membrane assemblies and membrane related materials; in particular, we elucidate the interaction of several polyene antibiotics, including amphotericin A, amphotericin B and nystatin, with a model membrane system composed of dipalmitoylphosphatidylcholine bilayers.

Levin, Ira W.; Lewis, E. Neil

1989-12-01

185

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

NASA Astrophysics Data System (ADS)

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

Syta, Olga; Rozum, Karol; Choi?ska, Marta; Zieli?ska, Dobrochna; ?ukowska, Gra?yna Zofia; Kijowska, Agnieszka; Wagner, Barbara

2014-11-01

186

Raman spectroscopy of gliomas: an exploratory study  

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

187

Measuring Rocket Engine Temperatures with Hydrogen Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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

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

2001-01-01

188

Coherent Raman spectroscopy for supersonic flow measurments  

NASA Technical Reports Server (NTRS)

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

She, C. Y.

1986-01-01

189

Applications of Raman spectroscopy to library heritage.  

PubMed

This work reports some different applications of Raman spectroscopy, a high sensitive non-destructive technique, to the conservation of Library Heritage. By Raman spectroscopy we were able to detect the chemical mechanisms leading to cellulose degradation, identifying the different functional groups formed during the paper ageing. This kind of information is fundamental to choose a suited restoration treatment. A second reported application is the identification of pigments used to decorate paper and parchments. We report some results obtained from analysis of a XV and a XIII century illuminations. PMID:11836947

Bicchieri, M; Nardone, M; Sodo, A

2001-01-01

190

Application of Raman Spectroscopy and Surface-Enhanced Raman Scattering to the Analysis of Synthetic Dyes Found in Ballpoint Pen Inks  

Microsoft Academic Search

The applicability of Raman spectroscopy and surface-enhanced Raman scattering (SERS) to the analysis of synthetic dyes com- monly found in ballpoint inks was investigated in a comparative study. Spectra of 10 dyes were obtained using a dispersive system (633 nm, 785 nm lasers) and a Fourier transform system (1064 nm laser) under different analytical conditions (e.g., powdered pigments, solutions, thin

Irina Geiman; Marco Leona; John R. Lombardi

2009-01-01

191

Journal of Raman Spectroscopy 36 [9] (2005) 884-890 Comparisons were drawn from Raman  

E-print Network

- 1 - Journal of Raman Spectroscopy 36 [9] (2005) 884-890 Comparisons were drawn from Raman-14Dec2006 Author manuscript, published in "Journal of Raman Spectroscopy 36 (2005) 884-890" #12;- 2 models for the understanding of the Raman signature of lustre ceramics and lustre- painted glasses

Paris-Sud XI, Université de

192

JOURNAL OF RAMAN SPECTROSCOPY, VOL. 29, 291295 (1998) Comparative Determination of Absolute Raman  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY, VOL. 29, 291Ã?295 (1998) Comparative Determination of Absolute Raman method to determine quantitatively minority phases of a-GaN in b-GaN by means of Raman spectroscopy.5 Universita t Paderborn, FB 6-Physik, D-33098 Paderborn, Germany Absolute Raman scattering efficiencies

Nabben, Reinhard

193

UV Raman spectroscopy of hydrocarbons.  

PubMed

In this paper, the UV Raman spectra of a large number of saturated and alkyl-substituted monocyclic, bicyclic and polycyclic aromatic hydrocarbons are obtained at 220 and 233 nm excitation wavelengths. Also included are nitrogen- and sulphur-containing hydrocarbons. The spectra obtained are fluorescence free, even for such highly fluorescent compounds as perylene, consistent with earlier reports of UV Raman spectra of hydrocarbons. The hydrocarbon UV Raman spectra exhibit greatly improved signal-to-noise ratio when in the neat liquid or solution state compared with the neat solid state, suggesting that some surface degradation occurs under the conditions used here. Assignments are given for most of the bands and clear marker bands for the different classes of hydrocarbons are readily observable, although their relative intensities vary greatly. These results are discussed in the context of structure and symmetry to develop a consistent, molecular-based model of vibrational group frequencies. PMID:15482987

Loppnow, G R; Shoute, L; Schmidt, K J; Savage, A; Hall, R H; Bulmer, J T

2004-11-15

194

Planetary surface exploration using Raman spectroscopy for minerals and organics  

NASA Astrophysics Data System (ADS)

Raman spectroscopy has been identified as one of the primary techniques for planetary surface mineralogy. It is widely used as a laboratory technique since it can identify nearly all crystalline mineral phases. Using a small spot size on the surface (on the order of a micron), mineral phases can be mapped onto microscopic images preserving information about surface morphology. As a result, this technique has been steadily gaining support for in situ exploration of a variety of target bodies, for example Mars, the Moon, Venus, asteroids, and comets. In addition to in situ exploration, Raman spectroscopy has been identified as a feasible means for pre-selection of samples on Mars for subsequent return to Earth. This is in part due to the fact that Raman can detect many organics in addition to minerals. As a result, the most relevant rock samples containing organics (potentially fossil biosignatures) may potentially be selected for return to Earth. We present a next-generation instrument that builds on the widely used 532 nm Raman technique to provide a means for performing Raman spectroscopy without the background noise that is often generated by fluorescence of minerals and organics. We use time-resolved laser spectroscopy to eliminate this 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 temporal resolution. We will address the challenges of analyzing surface materials, often organics, that exhibit short-lifetime fluorescence. We will present result on planetary analog samples to demonstrate the instrument performance including fluorescence rejection.

Blacksberg, J.; Alerstam, E.; Maruyama, Y.; Charbon, E.; Rossman, G. R.; Shkolyar, S.; Farmer, J. D.

2013-12-01

195

Coherent Raman dual-comb spectroscopy and imaging  

NASA Astrophysics Data System (ADS)

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

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

2014-11-01

196

RAMAN SPECTROSCOPY OF NANOSTRUCTURES POST DOCTORAL POSITION, PHOTONICS GROUP,  

E-print Network

involves developing new platforms to use surface enhanced Raman spectroscopy (SERS) to study biologicalRAMAN SPECTROSCOPY OF NANOSTRUCTURES POST DOCTORAL POSITION, PHOTONICS GROUP, UNIVERSITY OF TORONTO is Raman spectroscopy of colloidal quantum dots and in particular metallic nanoparticles. The project

197

NIR and VIS-raman spectroscopy of CVD diamond films  

Microsoft Academic Search

Raman spectroscopy is a widely used method for the analysis of CVD diamond layers, because it enables to distinguish between different carbon phases, such as diamond, graphite, amorphous carbon and nanocrystalline carbon, which are all commonly present in CVD diamond films. A comparison of visible Raman spectroscopy and near-infrared Raman spectroscopy applied to CVD diamond layers on various substrates (Si,

M. Griesser; M. Grasserbauer; R. Kellner; S. Bohr; R. Haubner; B. Lux

1995-01-01

198

The second order Raman spectroscopy in carbon crystallinity  

Microsoft Academic Search

Cellulose was heated in the absence\\/presence of B to determine crystallinity changes due to heat treatment and B doping with the objectives of evaluating the characteristics of the second order Raman spectroscopy in comparison with X-ray diffraction (XRD) and the first order Raman spectroscopy. The crystallinity determined by XRD was similar to those of the first order Raman spectroscopy; crystallinity

Young-Jae Lee

2004-01-01

199

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

NASA Astrophysics Data System (ADS)

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

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

2011-03-01

200

Development of a drug assay using surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

1990-07-01

201

The analysis of colored acrylic, cotton, and wool fibers using Raman spectroscopy  

Microsoft Academic Search

There has been a resurgence in Raman spectroscopy for its application in forensic science. This method allows for the measurement of the inelastic scattering of light due to the vibrational modes of a molecule when irradiated by an intense monochromatic source such as a laser. The Raman technique presents advantages such as its non-destructive nature, its fast analysis time, and

Patrick Buzzini

202

Raman spectroscopy of newberyite, hannayite and struvite  

NASA Astrophysics Data System (ADS)

The phosphate minerals hannayite, newberyite and struvite have been studied by Raman spectroscopy using a thermal stage. Hannayite and newberyite are characterised by an intense band at around 980 cm -1 assigned to the v symmetric stretching vibration of the HPO 4 units. In contrast the symmetric stretching mode is observed at 942 cm -1 for struvite. The Raman spectra are characterised by multiple v anti-symmetric stretching bands and v and v bending modes indicating strong distortion of the HPO 4 and PO 4 units. Hannayite and newberyite are defined by bands at 3382 and 3350 cm -1 attributed to HOPO 3 vibrations and hannayite and struvite by bands at 2990, 2973 and 2874 assigned to NH 4+ bands. Raman spectroscopy has proven most useful for the analysis of these 'cave' minerals where complex paragenetic relationships exist between the minerals.

Frost, Ray L.; Weier, Matt L.; Martens, Wayde N.; Henry, Dermot A.; Mills, Stuart J.

2005-11-01

203

Surface enhanced Raman spectroscopy on chip  

NASA Astrophysics Data System (ADS)

In this paper we report on an integrated spectrometer device, fabricated in epoxy resist (SU-8) on silicon, designed for Raman spectroscopy and direct coupling to a CCD element. Furthermore a nanostructured surface is prepared on a gold coated silicon chip to enhance the Raman signal. We show examples of low resolution Surface Enhanced Raman Spectra (SERS) recorded with this chip and provide an outlook on the future possibilities. Traditional optical detection in Lab-on-Chip devices often requires sample pretreatment including chemical reactions in order to identify and detect a certain substance (e.g. attachment of a fluorescent marker). The basic idea in bringing Raman spectroscopy to the chip is to avoid these chemical reactions and directly enable identification of the substance by its Raman spectrum. Two different methods were used to prepare the nanostructured surfaces. The first method is based on an aqueous suspension of gold nanoparticles and polystyrene beads deposited on a gold surface. The suspension was dried and the polystyrene beads were removed using an appropriate solvent (methane dichloride). The second approach includes gold coated random silicon nanostructures so-called "black silicon". The surfaces were characterized using a commercial Raman spectrometer and the enhancement factor was found to be strongly dependant on the concentration on the sample surface. The surface was impregnated with a droplet (10 ?l, 100 ?M) of Rhodamin 6G and Nileblue respectively. Using the on-chip spectrometer we have recorded surface enhanced Raman spectra of Nileblue and Rhodamin 6G respectively. The results show that these systems are suitable for low cost extremely compact Raman sensors with possible applications reaching from process monitoring to homeland security and point of care devices.

Hubner, Jorg; Anhøj, Thomas; Pedersen, Sarah; Zauner, Dan A.; Jorgensen, Anders M.; Blagoi, Gabriella; Talian, Ivan; Hansen, Ole

2008-02-01

204

Raman spectroscopy of low-dimensional semiconductors  

Microsoft Academic Search

Raman spectroscopy is widely used to study the vibrational and structural properties of single crystals. More recently, in the fields of chemistry, physics, and engineering, interest in the properties of small objects has arisen. Small objects include microcrystalline materials, artificially layered semiconductor structures, and colloidal suspensions. The reason for this recent interest is that these objects often display unique electronic

Philippe M. Fauchet; Ian H. Campbell

1988-01-01

205

Raman spectroscopy of nanostructures and nanosized materials  

Microsoft Academic Search

The interest of micro and tip-enhanced Raman spectroscopy to analyze nanosized and nanostructured materials, chiefly semiconductors, oxides and pristine or functionalized carbon nanotubes, is reviewed at the light of the contributions to this special issue. Particular attention is paid to the fact that chemical reactions, size or shape distribution, defects, strain and couplings may add to nano-dimensionality in defining the

Gwénaël Gouadec; Philippe Colomban

2007-01-01

206

Rapid identification of mycobacteria by Raman spectroscopy  

Microsoft Academic Search

A number of rapid identification methods have been developed to improve the accuracy for diagnosis of tuberculosis and to speed up the presumptive identification of Mycobacterium species. Most of these methods have been validated for a limited group of microorganisms only. Here, Raman spectroscopy was compared to 16S rRNA sequencing for the identification of Mycobacterium tuberculosis complex strains and the

P. C. A. M. Buijtels; H. F. M. Willemse-Erix; P. L. C. Petit; H. P. Endtz; G. J. Puppels; H. A. Verbrugh; Belkum van A. F; D. van Soolingen; K. Maquelin

2008-01-01

207

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

208

Optical Coherence Tomography and Raman Spectroscopy of the retina  

SciTech Connect

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

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

2009-01-16

209

Multicomponent blood analysis by near-infrared Raman spectroscopy.  

PubMed

We demonstrate the use of Raman spectroscopy to measure the concentration of many important constituents (analytes) in serum and whole blood samples at physiological concentration in vitro across a multipatient data set. A near-infrared (830-nm) diode laser generates Raman spectra that contain superpositions of Raman signals from different analytes. Calibrations for glucose, cholesterol, urea, and other analytes are developed by use of partial least-squares cross validation. We predict six analytes in serum with significant accuracy in a 66-patient data set, using 60-s spectra. The calibrations are shown to be fairly robust against system drift over the span of seven weeks. In whole blood, a preliminary analysis yields accurate predictions of some of the same analytes and also hematocrit. The results hold promise for potential medical applications. PMID:18319874

Berger, A J; Koo, T W; Itzkan, I; Horowitz, G; Feld, M S

1999-05-01

210

Scanning Raman spectroscopy for characterizing compositionally spread films.  

PubMed

Composition-spread La(1-x)SrxMnO3 thin films were prepared by pulsed laser deposition technique from LaMnO3 and SrMnO3 targets. The films were epitaxial with a continuous variation of the out-of-plane lattice parameter along the direction of composition gradient. Scanning Raman spectroscopy has been employed as a nondestructive tool to characterize the composition-spread films. Raman spectra showed the variation of the structural, Jahn Teller distortions and the presence of coexisting phases at particular compositions that are in agreement with the previous observation on the single-crystal samples. Raman spectra on the continuous composition-spread film also reveal the effect of disorder and strain on the compositions. PMID:15638485

Venimadhav, A; Yates, K A; Blamire, M G

2005-01-01

211

Q-Switched Raman laser system  

DOEpatents

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

George, E. Victor (Livermore, CA)

1985-01-01

212

FT-Raman spectroscopy study of human breast tissue  

NASA Astrophysics Data System (ADS)

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

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

2004-07-01

213

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

NASA Astrophysics Data System (ADS)

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

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

2012-01-01

214

Bright emission from a random Raman laser  

PubMed Central

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

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

2014-01-01

215

Intrinsic Raman spectroscopy for quantitative biological spectroscopy Part II  

PubMed Central

We demonstrate the effectiveness of intrinsic Raman spectroscopy (IRS) at reducing errors caused by absorption and scattering. Physical tissue models, solutions of varying absorption and scattering coefficients with known concentrations of Raman scatterers, are studied. We show significant improvement in prediction error by implementing IRS to predict concentrations of Raman scatterers using both ordinary least squares regression (OLS) and partial least squares regression (PLS). In particular, we show that IRS provides a robust calibration model that does not increase in error when applied to samples with optical properties outside the range of calibration. PMID:18711512

Bechtel, Kate L.; Shih, Wei-Chuan; Feld, Michael S.

2009-01-01

216

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

217

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

NASA Technical Reports Server (NTRS)

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

She, C. Y.

1983-01-01

218

Detection Of Biochips By Raman And Surface Enhanced Raman Spectroscopies  

NASA Astrophysics Data System (ADS)

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

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

2010-08-01

219

Raman amplifiers and fiber lasers  

Microsoft Academic Search

The summary form only given. Stimulated Raman scattering (SRS) is a process by which energy is transferred from one wavelength to the next through a nonlinear scattering process. This phenomenon can be used to Raman amplify signals in a telecommunication systems. In this tutorial, the process of SRS is reviewed; and the advantages of Raman pumping a transmission span, improved

C. Headley

2003-01-01

220

In situ high P-T Raman spectroscopy and laser heating of carbon dioxide Mario Santoro,a)  

E-print Network

absorb the incoming Nd:YLF laser and heat the sample. The average sample temperature was accurately of the absorber determined by fitting the thermal radiation spectrum to the Planck radiation law to planetary science. Shock wave techniques provide methods for access- ing extreme high P-T conditions

Lin, Jung-Fu "Afu"

221

Raman spectroscopy of shocked water  

SciTech Connect

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

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

1985-08-01

222

Raman under nitrogen. The high-resolution Raman spectroscopy of crystalline uranocene, thorocene, and ferrocene.  

PubMed

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 A) and krypton (6764 A) 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, (COT)2-, 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 approximately 460 cm(-1) was also observed. The 460 cm(-1) band is greatly enhanced relative to the vibrational Raman transitions with excitations 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 A excitation. Relativistic density functional theory is used to provide theoretical interpretations of the measured spectra. PMID:15268415

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

2004-02-01

223

Raman Spectroscopy of Soft Musculoskeletal Tissues  

PubMed Central

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

Esmonde-White, Karen

2015-01-01

224

Candida parapsilosis Biofilm Identification by Raman Spectroscopy  

PubMed Central

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

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

2014-01-01

225

Metallized Capillaries as Probes for Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

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

Pelletier, Michael

2003-01-01

226

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

USGS Publications Warehouse

Raman spectral parameters for the Raman ??1 (1285??cm- 1) and 2??2 (1388??cm- 1) bands for CO2 and for the O-H stretching vibration band of H2O (3600??cm- 1) were determined in H2O-CO2 fluid inclusions. Synthetic fluid inclusions containing 2.5 to 50??mol% CO2 were analyzed at temperatures equal to or greater than the homogenization temperature. The results were used to develop an empirical relationship between composition and Raman spectral parameters. The linear peak intensity ratio (IR = ICO2/(ICO2 + IH2O)) is related to the CO2 concentration in the inclusion according to the relation:Mole % C O2 = e- 3.959 IR2 + 8.0734 IRwhere ICO2 is the intensity of the 1388 cm- 1 peak and IH2O is the intensity of the 3600 cm- 1 peak. The relationship between linear peak intensity and composition was established at 350????C for compositions ranging from 2.5 to 50??mol% CO2. The CO2-H2O linear peak intensity ratio (IR) varies with temperature and the relationship between composition and IR is strictly valid only if the inclusions are analyzed at 350????C. The peak area ratio is defined as AR = ACO2/(ACO2 + AH2O), where ACO2 is the integrated area under the 1388??cm- 1 peak and AH2O is the integrated area under the 3600??cm- 1 peak. The relationship between peak area ratio (AR) and the CO2 concentration in the inclusions is given as:Mole % C O2 = 312.5 AR. The equation relating peak area ratio and composition is valid up to 25??mol% CO2 and from 300 to 450????C. The relationship between linear peak intensity ratio and composition should be used for inclusions containing ??? 50??mol% CO2 and which can be analyzed at 350????C. The relationship between composition and peak area ratios should be used when analyzing inclusions at temperatures less than or greater than 350????C (300-450) but can only be used for compositions ??? 25??mol% CO2. Note that this latter relationship has a somewhat larger standard deviation compared to the intensity ratio relationship. Calibration relationships employing peak areas for both members of the Fermi diad (??1 at 1285??cm- 1 and 2??2 at 1388??cm- 1) were slightly poorer than those using only the 2??2 (1388??cm- 1) member owing to interference from quartz peak at approximately 1160??cm- 1. The technique has been applied to natural low-salinity H2O-CO2 inclusions from the Butte, Montana, porphyry copper-molybdenum deposit. Carbon dioxide concentrations obtained range from below detection to 4.2??mol% CO2, and are in good agreement with concentrations determined previously based on microthermometric and petrographic observations. ?? 2007 Elsevier B.V. All rights reserved.

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

2007-01-01

227

Biomedical applications of laser spectroscopy  

NASA Astrophysics Data System (ADS)

Very soon after the invention of the laser, the use of the thermal effects of the radiation was introduced. Such techniques have been refined and the laser is now routinely used for treatment in many specialities. Photodynamic therapy (PDT) is a non-thermal modality employing the combination of a tumor-seeking agent and activating laser light. During the last 15 years laser spectroscopic techniques have also been developed providing powerful means for non-intrusive medical diagnostics of tissue in real time. At the beginning only few groups were involved in exploratory work, but successively the field has developed now to occupy a large number of research teams, which meet at large specialized conferences. We will here consider three aspects of laser diagnostics: fluorescence, Raman and near-IR, and elastic scattering spectroscopy, and we will also briefly discuss PDT. The activity in the field is very extensive, and rather than trying to give a full overview, illustrations from work performed at the Lund University Medical Laser Center will be given.

Svanberg, Sune

1999-07-01

228

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

NASA Astrophysics Data System (ADS)

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

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

2015-01-01

229

Surface-enhanced near-infrared Raman spectroscopy of nicotinamide adenine dinucleotides on a gold electrode  

Microsoft Academic Search

Near-infrared Fourier transform Raman spectroscopy was used to study the surface-enhanced Raman spectroscopy (SERS) behavior of nicotinamide adenine dinucleotide (NAD) on a gold electrode. It was found that the quality of SERS can be largely improved by using a near-infrared laser as the exciting source. Many bands, which cannot be enhanced in conventional SERS excited by visible light, can be

Yi-Jin Xiao; Wang Ting; Xun-Qing Wang; Gao Xiao-Xia

1997-01-01

230

Drug Stability Analysis by Raman Spectroscopy  

PubMed Central

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

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

2014-01-01

231

Characterization of diatomaceous silica by Raman spectroscopy.  

PubMed

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

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

2004-10-01

232

Raman spectroscopy of blood in-vitro  

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

233

A monolithic integrated low-threshold Raman silicon laser  

NASA Astrophysics Data System (ADS)

We present a monolithic integrated low-threshold Raman silicon laser based on silicon-on-insulator (SOI) rib waveguide ring cavity with an integrated p-i-n diode. The laser cavity consists of a race-track shaped ring resonator connected to a straight bus waveguide via a directional coupler which couples both pump and signal light into and out of the cavity. Reverse biasing the diode with 25V reduces the free carrier lifetime to below 1 ns, and stable, single-mode, continuous-wave (CW) Raman lasing is achieved with threshold of 20mW, slope efficiency of 28%, and output power of 50mW. With zero bias voltage, a lasing threshold of 26mW and laser output power >10mW can be obtained. The laser emission has high spectral purity with a side-mode suppression of >80dB and laser linewidth of <100 kHz. The laser wavelength can be tuned continuously over 25 GHz. To demonstrate the performance capability of the laser for gas sensing application, we perform absorption spectroscopy on methane at 1687 nm using the CW output of the silicon Raman laser. The measured rotationally-resolved direct absorption IR spectrum agrees well with theoretical prediction. This ring laser architecture allows for on-chip integration with other silicon photonics components to provide an integrated and scaleable monolithic device. By proper design of the ring cavity and the directional coupler, it is possible to achieve higher order cascaded Raman lasing in silicon for extending laser wavelengths from near IR to mid IR regions.

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

2008-02-01

234

Theoretical analysis of anharmonic coupling and cascading Raman signals observed with femtosecond stimulated Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We present a classical theoretical treatment of a two-dimensional Raman spectroscopy based on the initiation of vibrational coherence with an impulsive Raman pump and subsequent probing by two-pulse femtosecond stimulated Raman spectroscopy (FSRS). The classical model offers an intuitive picture of the molecular dynamics initiated by each laser pulse and the generation of the signal field traveling along the probe wave vector. Previous reports have assigned the observed FSRS signals to anharmonic coupling between the impulsively driven vibration and the higher-frequency vibration observed with FSRS. However, we show that the observed signals are not due to anharmonic coupling, which is shown to be a fifth-order coherent Raman process, but instead due to cascades of coherent Raman signals. Specifically, the observed vibrational sidebands are generated by parallel cascades in which a coherent anti-Stokes or Stokes Raman spectroscopy (i.e., CARS or CSRS) field generated by the coherent coupling of the impulsive pump and the Raman pump pulses participates in a third-order FSRS transition. Additional sequential cascades are discussed that will give rise to cascade artifacts at the fundamental FSRS frequencies. It is shown that the intended fifth-order FSRS signals, generated by an anharmonic coupling mechanism, will produce signals of ˜10-4 ?OD (change in the optical density). The cascading signals, however, will produce stimulated Raman signal of ˜10-2 ?OD, as has been observed experimentally. Experiments probing deuterochloroform find significant sidebands of the CCl3 bend, which has an E type symmetry, shifted from the A1 type C-D and C-Cl stretching modes, despite the fact that third-order anharmonic coupling between these modes is forbidden by symmetry. Experiments probing a 50:50 mixture of chloroform and d-chloroform find equivalent intensity signals of low-frequency CDCl3 modes as sidebands shifted from both the C-D stretch of CDCl3 and the C-H stretch of CHCl3. Such intermolecular sidebands are allowed in the cascade mechanism, but are expected to be extremely small in the fifth-order frequency modulation mechanism. Each of these observations indicates that the observed signals are due to cascading third-order Raman signals.

Mehlenbacher, Randy D.; Lyons, Brendon; Wilson, Kristina C.; Du, Yong; McCamant, David W.

2009-12-01

235

Understanding the Surface-Enhanced Raman Spectroscopy "Background" Sumeet Mahajan,,  

E-print Network

Understanding the Surface-Enhanced Raman Spectroscopy "Background" Sumeet Mahajan,,§ Robin M. Cole, 2009 Even 35 years after the discovery of surface-enhanced Raman spectroscopy (SERS) much remains transitions enhanced at rough metal surfaces, with Raman relaxation of the excited electron followed

Steiner, Ullrich

236

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

237

Measurement of dna adducts using surface?enhanced Raman spectroscopy  

Microsoft Academic Search

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

A. Helmenstine; M. Uziel

1993-01-01

238

Near infrared Raman spectroscopy for Alzheimer's disease detection  

NASA Astrophysics Data System (ADS)

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

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

2005-08-01

239

NIR Raman spectroscopy in medicine and biology: results and aspects  

NASA Astrophysics Data System (ADS)

Analyses of biomaterial by 'classical' Raman spectroscopy with excitation in the visible range has not been possible since the fluorescence of many essential constituents of all animal and plant cells and tissues overlays the Raman spectra completely. Fluorescence, however, is virtually avoided, when Raman spectra are excited with the Nd : YAG laser line at 1064 nm. Within seven dissertations we explored different fields of potential applications to medical diagnostics. Identification and qualification of tissues and cells is possible. Tumors show small but significant differences to normal tissues; in order to develop a reliable tool for tumor diagnostics more research is necessary, especially a collection of reference spectra in a data bank is needed. Raman spectra of biomineralization structures in teeth and bones show pathological tissues as well as the development of new mineralized structures. NIR Raman spectra of flowers, leaves, and fruit show, without special preparation, their constituents: alkaloids, the essential oils, natural dyes, flavors, spices and drugs. They allow application to taxonomy, optimizing plant breeding and control of food.

Schrader, B.; Dippel, B.; Erb, I.; Keller, S.; Löchte, T.; Schulz, H.; Tatsch, E.; Wessel, S.

1999-05-01

240

Single bacteria identification by Raman spectroscopy.  

PubMed

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

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

2014-01-01

241

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

242

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

NASA Astrophysics Data System (ADS)

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

Sil, Sanchita; Umapathy, Siva

2014-06-01

243

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. PMID:24155548

González-Solís, JL; Luévano-Colmenero, GH; Vargas-Mancilla, J

2013-01-01

244

Applications of Raman Spectroscopy to Virology and Microbial Analysis  

NASA Astrophysics Data System (ADS)

This chapter reports from the utilization of Raman spectroscopic techniques like Raman microscopy, Raman optical activity (ROA), UV-resonance Raman (UVRR)-spectroscopy, surface enhanced Raman spectroscopy (SERS), and tip-enhanced Raman spectroscopy (TERS) for the investigation of viruses and microorganisms, especially bacteria and yeasts for medical and pharmaceutical applications. The application of these Raman techniques allows for the analysis of chemical components of cells and subcellular regions, as well as the monitoring of chemical differences occurring as a result of the growth of microorganisms. In addition, the interaction of microorganisms with active pharmaceutical agents can be investigated. In combination with chemometric methods Raman spectroscopy can also be applied to identify microorganisms both in micro colonies and even on single cells.

Harz, Michaela; Stöckel, Stephan; Ciobot?, Valerian; Cialla, Dana; Rösch, Petra; Popp, Jürgen

245

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

SciTech Connect

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

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

2013-12-15

246

Dispersive Raman spectroscopy allows the identification and quantification of melanin types  

PubMed Central

Melanins are the most prevalent pigments in animals and are involved in visual communication by producing colored traits that often evolve as intraspecific signals of quality. Identifying and quantifying melanins are therefore essential to understand the function and evolution of melanin-based signals. However, the analysis of melanins is difficult due to their insolubility and the lack of simple methods that allow the identification of their chemical forms. We recently proposed the use of Raman spectroscopy as a simple, noninvasive technique that can be used to identify and quantify melanins in feathers and hairs. Contrarily, other authors later stated that melanins are characterized by a lack of defined Raman signals. Here, we use confocal Raman microscopy to confirm previous analyses showing that the two main chemical forms of melanins (eumelanin and pheomelanin) exhibit distinct Raman signal and compare different excitation wavelengths to analyze synthetic pheomelanin and natural melanins in feathers of different species of birds. Our analyses indicate that only laser excitation wavelengths below 1064 nm are useful for the analysis of melanins by Raman spectroscopy, and only 780-nm laser in the case of melanins in feathers. These findings show that the capacity of Raman spectroscopy to distinguish different chemical forms of melanins depends on laser power and integration time. As a consequence, Raman spectroscopy should be applied after preliminar analyses using a range of these parameters, especially in fragile biological tissues such as feathers.

Galván, Ismael; Jorge, Alberto

2015-01-01

247

Dispersive Raman spectroscopy allows the identification and quantification of melanin types.  

PubMed

Melanins are the most prevalent pigments in animals and are involved in visual communication by producing colored traits that often evolve as intraspecific signals of quality. Identifying and quantifying melanins are therefore essential to understand the function and evolution of melanin-based signals. However, the analysis of melanins is difficult due to their insolubility and the lack of simple methods that allow the identification of their chemical forms. We recently proposed the use of Raman spectroscopy as a simple, noninvasive technique that can be used to identify and quantify melanins in feathers and hairs. Contrarily, other authors later stated that melanins are characterized by a lack of defined Raman signals. Here, we use confocal Raman microscopy to confirm previous analyses showing that the two main chemical forms of melanins (eumelanin and pheomelanin) exhibit distinct Raman signal and compare different excitation wavelengths to analyze synthetic pheomelanin and natural melanins in feathers of different species of birds. Our analyses indicate that only laser excitation wavelengths below 1064 nm are useful for the analysis of melanins by Raman spectroscopy, and only 780-nm laser in the case of melanins in feathers. These findings show that the capacity of Raman spectroscopy to distinguish different chemical forms of melanins depends on laser power and integration time. As a consequence, Raman spectroscopy should be applied after preliminar analyses using a range of these parameters, especially in fragile biological tissues such as feathers. PMID:25897382

Galván, Ismael; Jorge, Alberto

2015-04-01

248

Deep Raman spectroscopy for the non-invasive standoff detection of concealed chemical threat agents.  

PubMed

Deep Raman spectroscopy has been utilized for the standoff detection of concealed chemical threat agents from a distance of 15 m under real life background illumination conditions. By using combined time and space resolved measurements, various explosive precursors hidden in opaque plastic containers were identified non-invasively. Our results confirm that combined time and space resolved Raman spectroscopy leads to higher selectivity towards the sub-layer over the surface layer as well as enhanced rejection of fluorescence from the container surface when compared to standoff spatially offset Raman spectroscopy. Raman spectra that have minimal interference from the packaging material and good signal-to-noise ratio were acquired within 5 s of measurement time. A new combined time and space resolved Raman spectrometer has been designed with nanosecond laser excitation and gated detection, making it of lower cost and complexity than picosecond-based laboratory systems. PMID:22608458

Izake, Emad L; Cletus, Biju; Olds, William; Sundarajoo, Shankaran; Fredericks, Peter M; Jaatinen, Esa

2012-05-30

249

Measuring molecular flows with high-resolution stimulated Raman spectroscopy  

NASA Technical Reports Server (NTRS)

It is proposed to use high-resolution stimulated Raman spectroscopy to directly measure high-speed molecular flow velocities in wind tunnels and in combustive chambers. A feasibility study indicates that flow speeds from Mach 0.04 up may be measured with the proposed method using available laser systems. It is pointed out that the success of the proposed technique will make it possible to measure all interesting flow parameters, i.e., species concentration, temperature, and velocity, in a time of less than 1 microsecond at a repetition rate of 10,000/s using a single experimental arrangement.

She, C. Y.; Fairbank, W. M., Jr.; Exton, R. J.

1981-01-01

250

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

251

Differential femtosecond coherent Stokes and anti-Stokes Raman spectroscopy  

E-print Network

We demonstrate a novel technique of coherent Raman spectroscopy with a femtosecond laser. We apply to a molecular sample a sequence of pairs of ultrashort excitation and probe pulses, with a linearly increasing time delay between the two pulses from one pair to the next. We measure, as a function of the delay, the intensity modulation in the signal resulting from the differential detection of the Stokes and anti-Stokes radiations generated at the sample. The Fourier transform of such time-domain signal reveals the spectrum of the excited vibrational Raman transitions. The experimental proof-of-principle demonstrates high resolution, broad spectral span and suppression of the non-resonant background, as well as sensitivity enhancement due to the differential detection.

Ideguchi, Takuro; Yan, Ming; Guelachvili, Guy; Hänsch, Theodor W; Picqué, Nathalie

2014-01-01

252

Noninvasive glucose sensing by transcutaneous Raman spectroscopy.  

PubMed

We present the development of a transcutaneous Raman spectroscopy system and analysis algorithm for noninvasive glucose sensing. The instrument and algorithm were tested in a preclinical study in which a dog model was used. To achieve a robust glucose test system, the blood levels were clamped for periods of up to 45 min. Glucose clamping and rise/fall patterns have been achieved by injecting glucose and insulin into the ear veins of the dog. Venous blood samples were drawn every 5 min and a plasma glucose concentration was obtained and used to maintain the clamps, to build the calibration model, and to evaluate the performance of the system. We evaluated the utility of the simultaneously acquired Raman spectra to be used to determine the plasma glucose values during the 8-h experiment. We obtained prediction errors in the range of ~1.5-2??mM. These were in-line with a best-case theoretical estimate considering the limitations of the signal-to-noise ratio estimates. As expected, the transition regions of the clamp study produced larger predictive errors than the stable regions. This is related to the divergence of the interstitial fluid (ISF) and plasma glucose values during those periods. Two key contributors to error beside the ISF/plasma difference were photobleaching and detector drift. The study demonstrated the potential of Raman spectroscopy in noninvasive applications and provides areas where the technology can be improved in future studies. PMID:25688542

Shih, Wei-Chuan; Bechtel, Kate L; Rebec, Mihailo V

2015-05-01

253

Single-molecule surface- and tip-enhanced raman spectroscopy  

Microsoft Academic Search

A review is given on single-molecule surface- and tip-enhanced Raman spectroscopy (SERS and TERS). It sketches the historical development along different routes toward huge near-field enhancements, the basis of single-molecule enhanced Raman spectroscopy; from SNOM to apertureless SNOM to tip-enhanced Raman spectroscopy (TERS) and microscopy; from SERS to single-molecule SERS to single-molecule TERS. The claim of extremely high enhancement factors

Bruno Pettinger

2010-01-01

254

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

E-print Network

Science (www.interscience.wiley.com). DOI: 10.1002/jrs.1337 Surface-enhanced Raman scattering from oxazine 720; Accepted 3 January 2005 Surface-enhanced Raman scattering (SERS) and surface-enhanced resonance Raman. Copyright 2005 John Wiley & Sons, Ltd. KEYWORDS: surface-enhanced Raman scattering; surface plasmons

Brolo, Alexandre G.

255

Lignin analysis by FT-Raman spectroscopy  

SciTech Connect

Traditional methods of lignin analysis, such as Klason (acid insoluble) lignin determinations, give satisfactory results, are widely accepted, and often are considered as standard analyses. However, the Klason lignin method is laborious and time consuming; it also requires a fairly large-amount of isolated analyte. FT-Raman spectroscopy offers an opportunity to simplify and speed up lignin analyses. FT-Raman data for a number of hardwoods (angiosperms) and softwoods (gymnosperms) are compared with data obtained using other analytical methods, including Klason lignin (with corrections for acid soluble lignin), acetyl bromide, and FT-IR determinations. In addition, 10 different specimens of Nothofagus dombeyii (chosen because of the widely varying syringyl:guaiacyl monomer compositions of their lignins) were also analyzed. Lignin monomer compositions were determined by thioacidolysis of by nitrobenzene oxidation.

Agarwal, U.P.; Obst, J.R.; Cannon, A.B. [USDA Forest Products Lab., Madison, WI (United States)

1996-10-01

256

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

2009-07-01

257

Coherent Raman spectro-imaging with laser frequency combs  

E-print Network

Optical spectroscopy and imaging of microscopic samples have opened up a wide range of applications throughout the physical, chemical, and biological sciences. High chemical specificity may be achieved by directly interrogating the fundamental or low-lying vibrational energy levels of the compound molecules. Amongst the available prevailing label-free techniques, coherent Raman scattering has the distinguishing features of high spatial resolution down to 200 nm and three-dimensional sectioning. However, combining fast imaging speed and identification of multiple - and possibly unexpected- compounds remains challenging: existing high spectral resolution schemes require long measurement times to achieve broad spectral spans. Here we overcome this difficulty and introduce a novel concept of coherent anti-Stokes Raman scattering (CARS) spectro-imaging with two laser frequency combs. We illustrate the power of our technique with high resolution (4 cm-1) Raman spectra spanning more than 1200 cm-1 recorded within le...

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

2013-01-01

258

Frequency measurements of hyperfine splittings in ground rovibronic states of I $\\\\bf_2$ by stimulated resonant Raman spectroscopy  

Microsoft Academic Search

Measurements of hyperfine splittings in the ground electronic state of $\\\\rm I_2$ have been performed by stimulated Raman spectroscopy. An argon laser emitting at 514.5 nm, drives the coherence between hyperfine levels of the J\\

J.-P. Wallerand; F. du Burck; B. Mercier; A. N. Goncharov; M. Himbert; C. J. Bordé

1999-01-01

259

New detector technologies and their impact on Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The latest generation of solid state detectors including Charged-Coupled Devices (CCD) and Charge-Injection Devices will be reviewed. Over the last several years, these detectors have contributed to major advances in Raman spectroscopy. Compact Raman systems using diode laser excitation, fiber-optic probes, and new generations of imaging spectrometers have been developed. New approaches for implementing very high throughput monochromators will be discussed, and their impact on the overall Raman system considered. Detection sensitivities obtained using these new optical geometries and array detector technologies are truly astounding. Even at an analyte concentration of a few ppm, a spectrum with several identifiable peaks can be obtained in a mater of seconds. This high sensitivity coupled with the ability of fiber optics to provide remote as well as in-situ sampling now make Raman a technique appropriate for many medical, environmental, and industrial applications. An overview of combining proper optical systems with currently available and soon to be introduced detectors will be presented. A variety of operating parameters for today's and tomorrow's arrays including readout noise, quantum efficiency, dark current, cosmic ray noise, and readout modes will be considered.

Denton, M. Bonner; Gilmore, D. A.

1995-05-01

260

In vivo lipidomics using single-cell Raman spectroscopy  

PubMed Central

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

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

2011-01-01

261

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

262

High purity efficient first Stokes Raman laser  

NASA Astrophysics Data System (ADS)

The subject of the solid-state Raman frequency conversion to the yellow frequency spectra has been an active topic since the mid 1990's, because of its application in bio-medical and astronomy fields. However, the yellow laser performance is often limited because of the cascade conversion to second or higher Stokes. This cascade conversion not only limits the conversion efficiency and the output power of the first Stokes, but also degrades the pulse and the beam profile of the first Stokes. We present a type of polarization coupled Raman resonator, in which the higher order ( the second Stokes and higher ) laser output can be dramatically suppressed. Our Raman resonator is pumped by a Q-switched and frequency doubled slab laser, and we can get an almost pure (P559/(P559 +P532)>99%) 559 nm yellow light output with an efficiency over 39% from 532 nm to 559 nm. The resonator includes a high reflection rear mirror, a KGW crystal, a polarization coupled input/output element, and a high reflection output coupler of 559 nm (R559 nm = 0.6). Furthermore, we have proposed an improvement of this polarization coupled Raman resonator. The theoretical calculations of the temporal and spatial dependent Raman conversion equations show that the conversion efficiency of the first order Stokes is greatly enhanced with an additional?/2 waveplate for 589 nm and the BBO crystal.

Liu, Xiaomeng; Liu, Qinyong; Li, Daijun; Du, Keming

2015-02-01

263

Raman Spectroscopy and instrumentation for monitoring soil carbon systems.  

SciTech Connect

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

Stokes, D.L.

2003-12-08

264

J. Raman Spectroscopy 38 [6] (2007) 598-603 Special Issue Raman spectroscopy of Nanomaterials, Ph. Colomban & G. Gouadec, Guest Editors  

E-print Network

in "Journal of Raman Spectroscopy 38, 6 (2007) 598-603" DOI : 10.1002/jrs.1749 #12;INTRODUCTIONJ. Raman Spectroscopy 38 [6] (2007) 598-603 Special Issue Raman spectroscopy of Nanomaterials, Ph. Colomban & G. Gouadec, Guest Editors Raman Spectroscopy of Nanostructures and Nanosized Materials Gwénaël

Paris-Sud XI, Université de

265

Micro and two-dimensional NIR FT raman spectroscopy  

Microsoft Academic Search

The former major problem in conventional Raman spectroscopy in the visible range, the disturbing fluorescence of impurities, has now been eliminated: Raman spectra can be excited by light quanta in the near-infrared range, the energy of which is too low to excite fluorescence spectra. An inherent disadvantage of this technique, the v4-dependence of the intensity of the Raman radiation, is

B. Schrader; G. Baranovi?; S. Keller; J. Sawatzki

1994-01-01

266

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

267

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

268

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

E-print Network

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

269

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

Microsoft Academic Search

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

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

1994-01-01

270

Raman conversion of femtosecond laser pulses in crystals Raman conversion of femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

The processes of transient Raman generation and Raman amplification in KGd(WO4)2 (KGW) crystals pumped by laser pulses with the width of about 150 fs were studied experimentally. For excitation, Bessel beams were used. Gaussian beams of Stokes and laser radiation were used at amplification stage. Raman shifts of 768 or 901 cm-1 were obtained depending on orientation of KGW crystals. For optimal conditions the gain was more than 100. The conversion efficiency of amplifying (pump) radiation into amplified Stokes radiation reached 50 %.

Orlovich, V. A.; Malakhov, Yu I.; Popov, Yu M.; Busko, D. N.; Danailov, M. B.; Demidovich, A. A.; Apanasevich, P. A.; Chulkov, R. V.

2012-11-01

271

Coronagraphic Notch Filter for Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

A modified coronagraph has been proposed as a prototype of improved notch filters in Raman spectrometers. Coronagraphic notch filters could offer alternatives to both (1) the large and expensive double or triple monochromators in older Raman spectrometers and (2) holographic notch filters, which are less expensive but are subject to environmental degradation as well as to limitations of geometry and spectral range. Measurement of a Raman spectrum is an exercise in measuring and resolving faint spectral lines close to a bright peak: In Raman spectroscopy, a monochromatic beam of light (the pump beam) excites a sample of material that one seeks to analyze. The pump beam generates a small flux of scattered light at wavelengths slightly greater than that of the pump beam. The shift in wavelength of the scattered light from the pump wavelength is known in the art as the Stokes shift. Typically, the flux of scattered light is of the order of 10 7 that of the pump beam and the Stokes shift lies in the wave-number range of 100 to 3,000 cm 1. A notch filter can be used to suppress the pump-beam spectral peak while passing the nearby faint Raman spectral lines. The basic principles of design and operation of a coronagraph offer an opportunity for engineering the spectral transmittance of the optics in a Raman spectrometer. A classical coronagraph may be understood as two imaging systems placed end to end, such that the first system forms an intermediate real image of a nominally infinitely distant object and the second system forms a final real image of the intermediate real image. If the light incident on the first telescope is collimated, then the intermediate image is a point-spread function (PSF). If an appropriately tailored occulting spot (e.g., a Gaussian-apodized spot with maximum absorption on axis) is placed on the intermediate image plane, then the instrument inhibits transmission of light from an on-axis source. However, the PSFs of off-axis light sources are formed off axis - that is, away from the occulting spot - so that they become refocused onto the final image plane.

Cohen, David; Stirbl, Robert

2004-01-01

272

Probing nanoscale ferroelectricity by ultraviolet Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Conventional vibrational spectroscopies operating in visible and infrared range fail to measure the phonon spectra of nanoscale ferroelectric structures because of extremely weak signals and the overwhelming substrate contribution. In this talk, application of ultraviolet (UV) Raman spectroscopy for studies of lattice dynamics and ferroelectric phase transitions in nanoscale ferroelectrics will be presented. We demonstrate that UV Raman spectroscopy is an effective technique allowing the observation of phonons and determination of the ferroelectric phase transition temperature (Tc) in nanoscale ferroelectrics, specifically, BaTiO3/SrTiO3 superlattices having the ferroelectric BaTiO3 layers as thin as 1 unit cell, and single BaTiO3 layers as thin as 4 nm. BaTiO3/SrTiO3 superlattices and ultrathin BaTiO3 films studied were grown by molecular beam epitaxy on SrTiO3 as well as GdScO3 and DyScO3 substrates. Excellent epitaxial quality and atomically abrupt interfaces are evidenced by X-ray diffraction and high resolution transmission electron microscopy. UV Raman results show that one-unit-cell thick BaTiO3 layers in BaTiO3/SrTiO3 superlattices are ferroelectric with the Tc as high as 250 K, and induce the polarization in much thicker SrTiO3 layers adjacent to them. The Tc in superlattices was tuned by hundreds of degrees from ˜170 to 650 K by varying the thicknesses of BaTiO3 and SrTiO3 layers. Using scandate substrates enables growth of superlattices with systematically changed coherent strain, thus allowing studying the stress effect on the ferroelectric phase transitions. UV Raman data are supported by the thermodynamic calculations of polarization in superlattices as a function of temperature. The work was done in collaboration with A. Soukiassian, W. Tian, D.G. Schlom, Y.L. Li, L.-Q. Chen, X.X. Xi (Pennsylvania State University), A. Bruchhausen, A. Fainstein (Centro Atomico Bariloche & Instituto Balseiro, Argentina), R. S. Katiyar (University of Puerto Rico), A. Cantarero (University of Valencia, Spain), K.J. Choi, D.M. Kim, C.-B. Eom (University of Wisconsin), H.P. Sun, X.Q. Pan (University of Michigan), S.M. Nakhmanson; K.M. Rabe (Rutgers University), Q.X. Jia (Los Alamos National Laboratory)

Tenne, Dmitri

2007-03-01

273

Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters  

PubMed Central

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

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

2013-01-01

274

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2005; 36: 648656  

E-print Network

Science (www.interscience.wiley.com). DOI: 10.1002/jrs.1356 Adaptive silver films for surface-enhanced Raman The interaction of biological molecules with a typical substrate for surface-enhanced Raman scattering (SERS excellent Raman enhancement through local restructuring of the metal surface while at the same time

Shalaev, Vladimir M.

275

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 2008; 39: 19071914  

E-print Network

2008 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jrs.2057 Surface-enhanced Raman article, we successfully used surface-enhanced Raman scattering (SERS) in the analysis of the alkaloid dye; coptisine; berberine; surface-enhanced Raman scattering; DFT; alkaloids INTRODUCTION The alkaloids represent

Lombardi, John R.

276

The hallmarks of breast cancer by Raman spectroscopy  

Microsoft Academic Search

This paper presents new biological results on ex vivo breast tissue based on Raman spectroscopy and demonstrates its power as diagnostic tool with the key advantage in breast cancer research. The results presented here demonstrate the ability of Raman spectroscopy to accurately characterize cancer tissue and distinguish between normal, malignant and benign types. The goal of the paper is to

H. Abramczyk; J. Surmacki; B. Brozek-Pluska; Z. Morawiec; M. Tazbir

2009-01-01

277

Quantitation of sulfate solubility in borosilicate glasses using Raman spectroscopy  

Microsoft Academic Search

Raman spectroscopy is used here as an innovative technique to investigate sulfate content in borosilicate glasses. Using Raman spectroscopy after having heated the material, the evolution of sulfate amounts can be followed as a function of temperature, time and chemical composition of the starting matrix. The accuracy of this technique was verified using electron probe micro analysis (EPMA), on two

M. Lenoir; A. Grandjean; S. Poissonnet; D. R. Neuville

2009-01-01

278

Surface-enhanced Raman spectroscopy: substrate-related issues  

Microsoft Academic Search

After over 30 years of development, surface-enhanced Raman spectroscopy (SERS) is now facing a very important stage in its\\u000a history. The explosive development of nanoscience and nanotechnology has assisted the rapid development of SERS, especially\\u000a during the last 5 years. Further development of surface-enhanced Raman spectroscopy is mainly limited by the reproducible\\u000a preparation of clean and highly surface enhanced Raman scattering (SERS)

Xiu-Mei Lin; Yan Cui; Yan-Hui Xu; Bin Ren; Zhong-Qun Tian

2009-01-01

279

Raman spectroscopy of aromatic acids adsorbed on oxidised aluminium foil  

Microsoft Academic Search

Adsorption of ortho- and para-phthalic acids on oxidised aluminium foil was investigated by Raman and surface-enhanced Raman spectroscopy (SERS). Without any treatment of the foil only a modified method of SERS provided spectroscopic evidence of the adsorption. However, by dissolving the metal aluminium from the Al2O3?Al?Al2O3 structure of the foil, the adsorption could be investigated by Raman spectroscopy without surface-enhanced

O. Klug; Gy. Parlagh; W. Forsling

1997-01-01

280

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

Microsoft Academic Search

Laser tissue welding involves the denaturing and partial renaturing of collagen and elastin. Tissues welded with NIR lasers tuned to the 1455 nm water absorption band have demonstrated high tensile strength with minimal collateral damage. To better understand the welding process, welded tissue samples were investigated using fluorescence imaging and Raman spectroscopy. As part of this study, human aorta, and

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

2002-01-01

281

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

NASA Technical Reports Server (NTRS)

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

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

2006-01-01

282

Highly efficient Raman distributed feedback fibre lasers.  

PubMed

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

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

2012-02-27

283

A continuous-wave Raman silicon laser.  

PubMed

Achieving optical gain and/or lasing in silicon has been one of the most challenging goals in silicon-based photonics because bulk silicon is an indirect bandgap semiconductor and therefore has a very low light emission efficiency. Recently, stimulated Raman scattering has been used to demonstrate light amplification and lasing in silicon. However, because of the nonlinear optical loss associated with two-photon absorption (TPA)-induced free carrier absorption (FCA), until now lasing has been limited to pulsed operation. Here we demonstrate a continuous-wave silicon Raman laser. Specifically, we show that TPA-induced FCA in silicon can be significantly reduced by introducing a reverse-biased p-i-n diode embedded in a silicon waveguide. The laser cavity is formed by coating the facets of the silicon waveguide with multilayer dielectric films. We have demonstrated stable single mode laser output with side-mode suppression of over 55 dB and linewidth of less than 80 MHz. The lasing threshold depends on the p-i-n reverse bias voltage and the laser wavelength can be tuned by adjusting the wavelength of the pump laser. The demonstration of a continuous-wave silicon laser represents a significant milestone for silicon-based optoelectronic devices. PMID:15716948

Rong, Haisheng; Jones, Richard; Liu, Ansheng; Cohen, Oded; Hak, Dani; Fang, Alexander; Paniccia, Mario

2005-02-17

284

Investigation of Ferroelectric Domain Walls by Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

Ferroelectric materials are characterized by an intrinsic spontaneous electric dipole moment that can be manipulated by the application of an electric field. Regions inside the crystal, known as domains, can have the spontaneous dipole moments oriented in a different direction than the surrounding crystal. Due to favorable piezoelectric, pyroelectric, electro-optic, and nonlinear optical properties, ferroelectric materials are attractive for commercial applications. Many devices, such as nonlinear frequency converters, require precisely engineered domain patterns. The properties of domains and their boundaries, known as domain walls, are vital to the performance and limitations of these devices. As a result, ferroelectric domains and the domain walls have been the focus of many scientific studies. Despite all this work, questions remain regarding their properties. This work is aimed at developing a better understanding of the properties of the domain wall using confocal Raman spectroscopy. Raman spectra taken from domain walls in Lithium Niobate and Lithium Tantalate reveal two distinct changes in the Raman spectra: (1) Shifts in frequency of the bulk Raman modes, which persists over a range of 0.2-0.5 mu m from the domain wall. The absence of this effect in defect free stoichiometric Lithium Tantalate indicates that the shifts are related to defects inside the crystal. (2) The presence of Raman modes corresponding to phonons propagating orthogonal to the laser beam axis, which are not collected in the bulk crystal. The phonons also preferential propagate normal to the domain wall. These modes are detected up to 0.35 mum from the domain wall. The observation and separation of these effects was made possible by the optimized spatial resolution (0.23 mum) of a home-built scanning confocal microscope and the fact that degeneracy of the transverse and longitudinal phonon polarization is lifted by polar phonons in Lithium Niobate and Lithium Tantalate. Raman investigations on other interfaces such as front, side and bottom surfaces revealed a similar appearance of modes due to distortion of wave fronts and reflection. These surfaces are studied to provide insight into mechanism that give rise to Raman modes typically absent for the particular orientation of the crystal.

Stone, Gregory A.

285

The Examination of Synthetic Organic Pigments in Modern Works of Art by Raman Microscopy and Laser Desorption Ionziation Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Raman spectroscopy in combination with laser desorption ionization mass spectrometry was used to examine samples from modern works of art by artists including Mark Rothko, Barnett Newman, and José de Rivera to identify the pigments present.

Lomax, S. Q.; Lomax, J. F.; De-Luca Westrate, A.

2014-06-01

286

Measurement of clathrate hydrates via Raman spectroscopy  

USGS Publications Warehouse

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

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

1997-01-01

287

Raman spectroscopy of human saliva for acute myocardial infarction detection  

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

288

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

289

Optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We present the optical diagnosis of dengue virus infection in human blood serum using Raman spectroscopy. Raman spectra were acquired from 18 blood serum samples using a laser at 532 nm as the excitation source. A multivariate regression model based on partial least-squares regression is developed that uses Raman spectra to predict dengue infection with leave-one-sample-out cross validation. The prediction of dengue infection by our model yields correlation coefficient r2 values of 0.9998 between the predicted and reference clinical results. The model was tested for six unknown human blood sera and found to be 100% accurate in accordance with the clinical results.

Saleem, M.; Bilal, M.; Anwar, S.; Rehman, A.; Ahmed, M.

2013-03-01

290

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

Microsoft Academic Search

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

Marieke Pudlas; Steffen Koch; Carsten Bolwien; Heike Walles

2010-01-01

291

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

292

Urinalysis by surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

The overall objective of this Small Business Technology Transfer Research program is the development of a fiber optic sensor suitable for surface-enhanced Raman spectroscopy that provides reversible, reproducible, quantitative measurements of trace chemicals. The sensor is intended to benefit NASA and the International Space Station in several areas. For example, the sensor could provide real-time measurements for space-based research in the areas of chemistry and biotechnology, it could provide continuous water quality monitoring in the life support systems, or it could provide astronaut health monitoring through urine and blood chemical analysis. This paper describes the development of the SERS based sensor and its application to astronaut health monitoring through urinalysis. .

Farquharson, Stuart; Lee, Yuan-Hsiang; Kwon, Hyeog; Shahriari, Mahmoud; Rainey, Petrie

2000-01-01

293

From Femtosecond Dynamics to Breast Cancer Diagnosis by Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2007-12-01

294

Structure and property investigations of TDO in aqueous phase by density functional theory, UV absorption, and Raman spectroscopy.  

PubMed

Density functional theory, UV absorption, and Raman spectroscopy are used to investigate the structure and properties of TDO in aqueous solution. The equilibrium structures, UV absorption spectra, interaction energies, and Raman spectroscopy data of TDO, AIMSA, and 12 TDO or AIMSA clusters are calculated. Raman spectroscopy experiments are carried out by 488 and 208 nm laser excitation. The Raman spectra of TDO in solid and aqueous phases have been compared, and the most possible structure for TDO in aqueous phase was deduced from analysis of the DFT calculations for the examined models, the experimental UV absorption spectrum, and Raman spectra of TDO. The interaction energy results show that TDO's solubility in water is originated from the TDO-water cyclic oligomer. The calculated UV absorption and Raman spectra of the I2·2H2O-cyc cluster model agree with the experimental results of TDO in aqueous solution very well. PMID:24712643

Shao, Jianzhong; Liu, Xiaoyun; Chen, Pin; Wu, Qiuxia; Zheng, Xuming; Pei, Kemei

2014-05-01

295

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

PubMed

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

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

2009-08-01

296

The many facets of Raman spectroscopy for biomedical analysis.  

PubMed

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

Krafft, Christoph; Popp, Jürgen

2015-01-01

297

Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers  

E-print Network

Hyperspectral Imaging with Stimulated Raman Scattering by Chirped Femtosecond Lasers Dan Fu, Gary imaging system using chirped femtosecond lasers to achieve rapid Raman spectra acquisition while retaining laser beams with an energy difference tuned to the vibrational frequency of the molecule of interest

Xie, Xiaoliang Sunney

298

Surface-enhanced Raman spectroscopy and correlated scanning electron microscopy of individual carbon nanotubes  

E-print Network

Surface-enhanced Raman spectroscopy and correlated scanning electron microscopy of individual, which generally limits its potential uses. Surface-enhanced Raman spectroscopy SERS can be used before and after depositing silver nanoparticles. Local regions exhibiting surface enhanced Raman

Cronin, Steve

299

Observation of Multiple Vibrational Modes in Ultrahigh Vacuum Tip-Enhanced Raman Spectroscopy Combined with Molecular-  

E-print Network

Observation of Multiple Vibrational Modes in Ultrahigh Vacuum Tip- Enhanced Raman Spectroscopy vacuum (UHV) tip-enhanced Raman spectroscopy (TERS). Several important new experimental features surfaces to be probed with unprecedented spatial and spectroscopic resolution. KEYWORDS: tip-enhanced Raman

Mohseni, Hooman

300

Neural network technologies in Raman spectroscopy of water solutions of inorganic salts  

NASA Astrophysics Data System (ADS)

This paper is devoted to successful application of artificial neural networks (ANN) for more precise analysis of Raman spectra, and for the solution of the inverse problems of laser Raman spectroscopy. The characteristic peculiarities of the valence band shape of Raman scattering by water molecules in the solutions of KBr, KCl, KI, NaCl, NaI electrolytes have been revealed. These peculiarities allow to perform non-contact recognition of salts type and determination of salt concentration in water solutions by means of artificial neural networks. We suppose that the classification algorithms using the artificial neural networks, applied in this study, may be also useful for other problems in Raman spectroscopy and in fluorimetry, and in application of these methods in ecology.

Dolenko, Tatiana A.; Burikov, Sergey A.; Sugonjaev, Alexander V.

2005-06-01

301

IR spectroscopy vs. Raman scattering by measurement of glucose concentration  

NASA Astrophysics Data System (ADS)

By developing a non-invasive device for glucose concentration measurement, two promising methods were compared for that aim. The Raman scattering using Laser at the wavelength 785 nm and the light scattering in R- and IR-range are demonstrated. An easy accessible and low-cost method for glucose concentration monitoring and management to avoid its complications will be a great help for diabetic patients. Raman Scattering is a promising method for noninvasively measuring of glucose and for the diagnostic of pathological tissue variations. Despite the power and the time of measurement can be reduced using enhanced Raman scattering, it will be difficult to develop a compatible device with low power Laser and low price for a non-invasive method for home monitoring. As using IR-spectroscopy at wavelengths slightly below 10000 nm, the absorption of glucose can be well discriminated from that of water, LED`s or LD's at these wavelengths are very expensive for this purpose. At wavelengths about 6250 and 7700 glucose has a less light absorption than water. Also slightly above 3000 nm glucose has a high absorption. There are also possibilities for the measurement in the NIR at wavelengths between 1400 nm and 1670 nm. Scattering measurements at wavelengths below 900 nm and our measurements with the wavelength about 640 nm give reproducible glucose dependence on the reflected light from a glucose solution at a constant temperature. A multi-sensor with different wavelengths and temperature sensor will be a good choice for in-vivo glucose monitoring.

Abdallah, O.; Hansmann, J.; Bolz, A.; Mertsching, H.

2010-11-01

302

Periodontitis diagnostics using resonance Raman spectroscopy on saliva  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

303

Applications of Raman lasers and amplifiers in fiber communication systems  

Microsoft Academic Search

The development of practical high power fiber lasers has created a resurgence of interest in Raman amplifiers for telecommunications systems. In this paper, we review the applications of cladding-pumped fiber lasers and cascaded Raman lasers to distributed and discrete, analog and digital Raman amplifiers at both 1.3 and 1.5 micrometers and to remotely pumped amplifiers in repeaterless communication systems.

Andrew J. Stentz

1998-01-01

304

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

305

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

PubMed Central

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

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

2010-01-01

306

Microsystem light source at 671 nm for shifted excitation Raman difference spectroscopy  

NASA Astrophysics Data System (ADS)

A novel compact wavelength stabilized diode laser system at 671 nm on a micro-optical bench as a light source for shifted excitation Raman difference spectroscopy (SERDS) is presented. Two broad-area gain media in separate laser cavities are used with two reflection Bragg-gratings with slightly different center wavelengths. A constant wavenumber difference of 13 cm-1 +/- 1.3 cm-1 together with a spectral width below 100 pm is obtained up to output powers of 250 mW. The suitability of this light source for SERDS is demonstrated using Raman spectra of ethanol with increasing concentrations of cresyl violet as fluorescent contaminant.

Maiwald, M.; Schmidt, H.; Sumpf, B.; Kronfeldt, H.-D.; Erbert, G.

2009-05-01

307

Multivariate classification of pigments and inks using combined Raman spectroscopy and LIBS  

Microsoft Academic Search

The authenticity of objects and artifacts is often the focus of forensic analytic chemistry. In document fraud cases, the\\u000a most important objective is to determine the origin of a particular ink. Here, we introduce a new approach which utilizes\\u000a the combination of two analytical methods, namely Raman spectroscopy and laser-induced breakdown spectroscopy (LIBS). The\\u000a methods provide complementary information on both

Marek Hoehse; Andrea Paul; Igor Gornushkin; Ulrich Panne

308

Visible and UV coherent Raman spectroscopy of dipicolinic acid  

PubMed Central

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

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

2005-01-01

309

High-pressure Raman spectroscopy of phase change materials  

SciTech Connect

We used high-pressure Raman spectroscopy to study the evolution of vibrational frequencies of the phase change materials (PCMs) Ge{sub 2}Sb{sub 2}Te{sub 5}, GeSb{sub 2}Te{sub 4}, and SnSb{sub 2}Te{sub 4}. We found that the critical pressure for triggering amorphization in the PCMs decreases with increasing vacancy concentration, demonstrating that the presence of vacancies, rather than differences in the atomic covalent radii, is crucial for pressure-induced amorphization in PCMs. Compared to the as-deposited amorphous phase, the pressure-induced amorphous phase has a similar vibrational spectrum but requires much lower laser power to transform into the crystalline phase, suggesting different kinetics of crystallization, which may have implications for applications of PCMs in non-volatile data storage.

Hsieh, Wen-Pin, E-mail: wphsieh@stanford.edu; Mao, Wendy L. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States) [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Geological and Environmental Sciences, Stanford University, Stanford, California 94305 (United States); Zalden, Peter [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States)] [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Wuttig, Matthias [I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen (Germany) [I. Physikalisches Institut (IA), RWTH Aachen University, 52056 Aachen (Germany); JARA – Fundamentals of Future Information Technology, RWTH Aachen University, 52056 Aachen (Germany); Lindenberg, Aaron M. [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States) [SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); SLAC National Accelerator Laboratory, PULSE Institute, Menlo Park, California 94025 (United States)

2013-11-04

310

Fundamental differences between micro- and nano-Raman spectroscopy  

Microsoft Academic Search

Summary Electric field polarization orientations and gradients in the near-field of near-field scanning optical microscope (NSOM) probes render nano-Raman fundamentally different from micro-Raman spectroscopy. With x-polarized light incident through an NSOM aperture, transmitted light has x, y and z components allowing nano-Raman investigators to probe a variety of polarization configurations. In addition, the strong field gradients in the near-field of

E. J. Ayars; C. L. Jahncke; M. A. Paesler; H. D. Hallen

2001-01-01

311

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

312

Micro-Raman investigation of stress distribution in laser drilled via structures  

Microsoft Academic Search

Through-wafer vertical electrical interconnects (vias) with diameters varied from 15 to 80?m were formed on Si substrates using a UV diode-pumped solid state laser (355nm). Micro-Raman spectroscopy was employed for the investigation of stress and structural changes induced in silicon within the heat-affected zone due to laser machining. A maximum stress of ?300MPa, as a result of laser drilling, was

J. Wasyluk; D. Adley; T. S. Perova; A. M. Rodin; J. Callaghan; N. Brennan

2009-01-01

313

Raman and surface-enhanced Raman spectroscopy of adsorbed phthalic acid on oxidized aluminum foil  

Microsoft Academic Search

Adsorption of phthalic acid on anodically oxidized aluminum has been investigated at different pHs and ionic strengths by means of FT-Raman and surface-enhanced FT-Raman spectroscopy (SERS). The surface-enhancement was achieved by deposition of silver sol after adsorption. The spectra of the surface species obtained by the two techniques were significantly different. Raman spectra of the adsorbed phthalic compounds were pH

O. Klug; Gy. Parlagh; W. Forsling

1998-01-01

314

Surface-enhanced Raman spectroscopy for homeland defense  

Microsoft Academic Search

Surface-enhanced Raman spectroscopy (SERS) is a spectroscopic technique that enables trace detection of analytes of relevance using fieldable equipment. SERS uses the enhanced Raman signals observed when an analyte adsorbs to a roughened metal substrate, generally gold, silver, or copper. Coupled to a microscope, single molecule detection has been demonstrated. With a fieldable instrument, enhancements of 108 compared to unenhanced

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

2004-01-01

315

The surface enhanced Raman spectroscopy of DCM in silver colloid  

Microsoft Academic Search

The surface enhanced Raman spectroscopy of DCM dye was firstly present in this paper. We have studied their chloride ion effects on the surface-enhanced Raman scattering (SERS) activities of the silver solution. For the positive charge dyes, no SERS could be observed without the addition of chloride ions for lack of the electrostatic interaction. The chloride ions served to enlarge

Shang-Yuan Feng; Jiesi Chen; Qisong Chen; Jianji Pan; Rong Chen; Shaojun Lin; Chao Li

2009-01-01

316

On the Contribution of Raman Spectroscopy to Forensic Science  

Microsoft Academic Search

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

Patrick Buzzini; Genevieve Massonnet

2010-01-01

317

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...

318

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

319

New dimensions in proteomic diagnostics using Raman spectroscopy  

Microsoft Academic Search

High-quality normal Raman spectra are derived from protein solutions with concentrations down to 1 ?M and 1 fmol of protein nondestructively probed within the excitation laser beam. These results are obtained using a drop coating deposition Raman (DCDR) method in which the solution of interest is microdeposited (or microprinted) on a compatible substrate, followed by solvent evaporation and backscattering detection.

Corasi Ortiz

2006-01-01

320

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

321

Raman spectroscopy of carbon nanohoops Hang Chen a,b  

E-print Network

in the characterization of CNTs due to its non- destructive nature and the ability to probe both elastic and electronic, the CPPs also deserve further examinations by Raman spectroscopy, which has been so instrumental

322

Surface enhanced Raman spectroscopy on a flat graphene surface  

E-print Network

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

Xu, Weigao

323

Quantitative biological Raman spectroscopy for non-invasive blood analysis  

E-print Network

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

Shih, Wei-Chuan

2007-01-01

324

Detection of Physiologically Relevant Alcohol Concentrations Using Raman Spectroscopy  

E-print Network

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

McKay, Joshua L.

2006-08-16

325

Raman Spectroscopy for the Investigation of Carbon Based Black Pigments  

NASA Astrophysics Data System (ADS)

Carbon based black pigments play an important role among artists' materials. The disordered structure of these materials is investigated by means of Raman spectroscopy, which helps in the comprehension of their production processes.

Coccato, A.; Jehlicka, J.; Moens, L.; Vandenabeele, P.

2014-06-01

326

Gated Raman spectroscopy (GRAS): A new experimental approach for the measurement of Raman signals of particles in suspension  

NASA Astrophysics Data System (ADS)

A new technique for the measurement of Raman spectra of small particles in suspension, such as biological cells, is described. The particles flow through a rectangular glass capillary mounted at the sample position of a laser Raman microspectrometer. The measuring volume inside the glass capillary is comparable to the volume of the particles. The elastic forward light scattering of the laser beam by the particles is used to monitor the presence of a particle in the measuring volume. Photon pulses from the Raman detector are counted only when a particle is inside the measuring volume. In this way the background signal caused by the suspending medium is suppressed, thus allowing measurement at very low particle concentrations. The technique, which is called gated Raman spectroscopy (GRAS) combines features such as: efficient light collection, suppression of background, and the possibility to use high laser powers. A great advantage is that this technique can be used for the study of (living) biological cells under physiological conditions. The GRAS technique is demonstrated with polystyrene particles and with unicellular algae chlorella vulgaris.

de Grooth, B. G.; de Mul, F. F. M.; Greve, J.

1984-02-01

327

Low-threshold semiconductor Raman laser  

SciTech Connect

A semiconductor Raman laser using the longitudinal optical (LO) phonon mode of GaP has a very low threshold compared to the transverse optical (TO) phonon mode of GaP and even compared to simulated Raman scatterings in various kinds of liquids and insulating solid materials. The lowest threshold value of the pulsed input optical power is 8 kW (5 x 10/sup 6/ W/cm/sup 2/) at room temperature. Far infrared radiation (24.8 ..mu..m) has been generated by placing both GaP with the LO phonon mode and GaAs with the TO phonon mode in a Fabry-Perot resonator. The maximum far infrared power has been 3 W.

Suto, K.; Nishizawa, J.

1983-08-01

328

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

329

Rapid monitoring of benzylpenicillin sodium using Raman and surface enhanced Raman spectroscopy.  

PubMed

At present, fluorescence spectroscopy, ultraviolet spectroscopy and infrared spectroscopy are usually used to detect drug molecules, however the information about using Raman spectroscopy to detect drug molecules is very few. In this work normal Raman spectroscopy and surface-enhanced Raman spectroscopy were utilized to study benzylpenicillin sodium (NaBP). The results show that NaBP is close to the surface of silver substrate through the carboxyl group, and the detection limit of NaBP is reduced to 1×10(-7) mol/L. Accordingly, the quantitative analysis of NaBP can be carried out in the range of 1×10(-4)-1×10(-7) mol/L concentration. And it is proved that NaBP is not stable in acid and alkali conditions and the decomposition reaction is very complex. PMID:25638429

Jiang, Xin; Qin, Xiaoyu; Yin, Di; Gong, Mengdi; Yang, Libin; Zhao, Bing; Ruan, Weidong

2015-04-01

330

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

E-print Network

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

Barros, E. B.

331

Surface Enhanced Raman Spectroscopy - Vibrational Spectroscopy of Adsorbates at the Metal-Electrolyte Interface  

Microsoft Academic Search

Surface enhanced Raman spectroscopy has been used to study the adsorption of pyridine and cyanide on Cu, Ag, and Au electrodes. The Raman spectra for pyridine on these three substrates closely resembled each other, and the Raman peaks exhibited small shifts from the corresponding peaks in an aqueous pyridine solution. The low frequency vibrational modes in the region 200–250 cm

B. H. Loo

1982-01-01

332

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.

2012-06-01

333

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

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

334

Raman spectroscopy of carbon nanotubes under axial strain and surface-enhanced Raman spectroscopy of individual carbon nanotubes  

Microsoft Academic Search

In this thesis, I present resonant Raman spectroscopy of individual carbon nanotube bundles under axial strains up to 17%. The main effect of this strain is to cause nanotube debundling. The G band Raman spectra of metallic and semiconducting nanotubes are found to respond differently to strain and debundling, giving insight into the nature of the broad metallic G- band

Rajay Kumar

2008-01-01

335

Single molecule Raman spectroscopy and local work function fluctuations  

E-print Network

Single molecule Raman spectroscopy provides information on individual molecules with vibrational-level resolution. The unique mechanisms leading to the huge Raman cross-section enhancement necessary for single molecule sensitivity are under intense investigation in several laboratories. We recently analyzed large spectral fluctuations in single molecule spectra of rhodamine 6G on silver surfaces (A. Weiss and G. Haran, J. Phys. Chem. B (2001), 105, 12348-12354). The appearance of the fluctuations in two particular vibrational bands, and their dependence on several parameters, suggested that they originate in a charge transfer interaction of an adsorbed molecule with the surface. We argued that the fluctuations are due to variations of the local work function at the position of the molecule. In the current paper the fluctuations are further analyzed in terms of the intensity ratio between a fluctuating and a quiescent band, and it is found that the distribution of this ratio is independent of laser power, unlike the correlation time of the fluctuations. We show that a simple model, based on the energetics of charge transfer, can be used to extract the local work function distribution from the intensity ratio distribution. In a second experiment, single molecule spectra are collected from colloids immersed in water and in glycerol and a threefold decrease in fluctuation rate is found in the more viscous fluid. This indicates that surface dynamics are indeed responsible for the fluctuations, involving the motion of the adsorbed molecule and possibly also that of surface silver atoms around it.

Gilad Haran

2004-08-02

336

Combustion Diagnosis By Coherent Anti-Stokes Raman Spectroscopy (CARS)  

NASA Astrophysics Data System (ADS)

Coherent anti-Stokes Raman spectroscopy (CARS) appears very promising for the remote, spatially and temporally precise probing of hostile combustion environments due to its large signal conversion efficiency and coherent signal nature. CARS is a wave mixing process in which incident laser beams at frequencies w1 and 0)2, with a frequency difference tuned to a Raman resonance in the molecular species being probed, interact to generate a coher-ent signal at frequency w3 = 2(.01 - w2. By analyzing the spectral distribution of the CARS signal, temperature measurements can be performed. Species concentration measurements derive from the intensity of the CARS radiation or, in certain cases, from its spectral shape. CARS spectra have been recorded in a variety of flames from the major flame constituents and generally show very good agreement with computer synthesized spectra. Significantly, CARS has been successfully demonstrated with both liquid and gaseous fuels in the primary zone and exhaust of practical combustors. Both thermometry and species concentration measurements have been performed. High pressure effects on CARS spectra have also been examined.

Hall, Robert J.; Eckbreth, Alan C.

1981-08-01

337

Recurrence prediction in oral cancers: a serum Raman spectroscopy study.  

PubMed

High mortality rates associated with oral cancers can be primarily attributed to the failure of current histological procedures in predicting recurrence. Identifying recurrence related factors can lead to improved prognosis, optimized treatment and enhanced overall outcomes. Serum Raman spectroscopy has previously shown potential in the diagnosis of cancers, such as head and neck, cervix, breast, oral cancers, and also in predicting treatment response. In the present study, serum was collected from 22 oral cancer subjects [with recurrence (n = 10) and no-recurrence (n = 12)] before and after surgery and spectra were acquired using a Raman microprobe coupled with a 40× objective. Spectral acquisition parameters were as follows: ?ex = 785 nm, laser power = 30 mW, integration time: 12 s and averages: 3. Data was analyzed in a patient-wise approach using unsupervised PCA and supervised PC-LDA, followed by LOOCV. PCA and PC-LDA findings suggest that recurrent and non-recurrent cases cannot be classified in before surgery serum samples; an average classification efficiency of ?78% was obtained in after-surgery samples. Mean and difference spectra and PCA loadings indicate that DNA and protein markers may be potential spectral markers for recurrence. RS of post surgery serum samples may have the potential to predict the probability of recurrence in clinics, after prospective large-scale validation. PMID:25619332

Sahu, Aditi; Nandakumar, Nikhila; Sawant, Sharada; Krishna, C Murali

2015-03-16

338

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

PubMed Central

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

Brauchle, Eva; Schenke-Layland, Katja

2013-01-01

339

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

340

Rapid detection of nasopharyngeal cancer using Raman spectroscopy and multivariate statistical analysis  

PubMed Central

Optical spectroscopic techniques, including Raman spectroscopy, have shown promise for in vivo cancer diagnostics in a variety of organs. In this study, the potential use of a home-made Raman spectral system with a millimeter order excitation laser spot size combined with a multivariate statistical analysis for the rapid detection and discrimination of nasopharyngeal cancer from normal nasopharyngeal tissue was evaluated. Raman scattering signals were acquired from 16 normal and 32 nasopharyngeal carcinoma tissue samples. Linear discriminant analysis (LDA) based on principal component analysis (PCA) and partial least squares (PLS) were employed to generate diagnostic algorithms for the classification of different nasopharyngeal tissue types. Spectral differences in Raman spectra between the two types of tissues were revealed; the normalized intensities of Raman peaks at 1,001, 1,207 and 1,658 cm?1 were more intense for nasopharyngeal carcinoma tissue compared to normal tissue, while Raman bands at 848, 936 and 1,446 cm?1 were stronger in normal nasopharyngeal samples. The PCA-LDA algorithm together with leave-one-out cross validation yields a diagnostic sensitivity of 81% and a specificity of 87%, while the PLS method coupled with subwindow permutation analysis improves the diagnostic sensitivity and specificity to 85 and 88%, respectively. Therefore, Raman spectroscopy combined with PCA-LDA/PLS demonstrated good potential for improving the clinical diagnosis of nasopharyngeal cancers.

LI, YONGZENG; HUANG, WEI; PAN, JIANJI; YE, QING; LIN, SHAOJUN; FENG, SHANGYUAN; XIE, SHUSEN; ZENG, HAISHAN; CHEN, RONG

2015-01-01

341

Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.  

DOEpatents

A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. A low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic transaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively.

Alfano, Robert R. (Bronx, NY); Wang, Wubao (Flushing, NY)

2003-05-06

342

Raman spectroscopy for forensic analysis of inks in questioned documents.  

PubMed

The methods for perpetrating forgery and alteration of documents are becoming increasingly more sophisticated. Forensic examinations of questioned documents routinely involve physical and chemical analysis of inks. Raman spectroscopy is a very attractive technique for ink analysis because it combines chemical selectivity with ease and fast analysis and it does not require sample preparation nor leads to destruction of the evidence. However, some limitations of this technique include low sensitivity and the overwhelming phenomenon of fluorescence, which can be solved by resonance Raman spectroscopy and surface-enhanced Raman spectroscopy. This article aims to demonstrate the great potential of the Raman-based techniques by providing an overview of their application to forensic examinations of ink evidence from pens and printers. Moreover, it is also addressed the chemistry of ink-paper interactions and the problematic of intersecting lines. PMID:24053882

Braz, André; López-López, Maria; García-Ruiz, Carmen

2013-10-10

343

Surface-enhanced Raman spectroscopy combined with atomic force microscopy for ultrasensitive detection of thrombin  

E-print Network

Surface-enhanced Raman spectroscopy combined with atomic force microscopy for ultrasensitive an ultrasensitive analytical method based on surface-enhanced Raman spectroscopy (SERS) exploiting a Raman probe applied techniques include fluo- rescence, surface-enhanced Raman spectroscopy (SERS)1 , surface plasmon

Tuscia, Università Degli Studi Della

344

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

PubMed Central

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

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

2012-01-01

345

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

NASA Astrophysics Data System (ADS)

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 70fs 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 2330cm-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 Q(2) to Q(20). The excitation of the Raman coherences is also very efficient; for laser irradiances of 5×1017W /m2, corresponding approximately to a 100?J, 70fs pulse focused to 50?m, 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.

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

2007-07-01

346

Drop Coating Deposition Raman Spectroscopy of Fluorescein Isothiocyanate Labeled Protein  

PubMed Central

Using bovine serum albumin (BSA) as the model protein normal Raman spectra of Fluorescein isothiocyanate (FITC) -conjugated protein was systematically studied for the first time using both solution and the drop coating deposition Raman (DCDR) sampling techniques. The FITC-BSA Raman spectra are dominated by the FITC Raman features that are strongly pH dependent. Current DCDR detection sensitivity obtained with a 10:1 FITC-BSA conjugate is 45 fmol in terms of total protein consumption and ~15 attomol at laser probed volume. Unlike the FITC-BSA solution Raman spectra where the FITC Raman features are photostable, concurrent FITC fluorescence and Raman photobleaching is observed in the DCDR spectra of FITC-BSA. While the FITC Raman photobleaching follows a single exponential decay function with a time constant independent of the FITC labeling ratio, the fluorescence background photobleaching is much more complicated and it depends strongly on the FITC labeling ratio and sample conditions. Mechanistically, the FITC Raman photobleaching is believed to be due to photochemical reaction of the FITC molecules in the electronically excited state. The FITC fluorescence photobleaching involves both concentration quenching and photochemical quenching, and the latter may involve a photochemical intermediate that is fluorescence inactive but Raman active. PMID:20925976

Vangala, Karthikeshwar; Jiang, Dongping; Zou, Sige; Pechan, Tibor

2011-01-01

347

Effects of O2CO2 polarization beating on femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy of O2  

Microsoft Academic Search

Femtosecond coherent anti-Stokes Raman scattering (fs-CARS) spectroscopy has recently emerged as a promising laser-based temperature-measurement technique in flames. In fs-CARS, the broad spectral bandwidths of the pump and Stokes lasers permit the coupling of each ro-vibrational Raman transition via a large number of pump-Stokes photon pairs, creating a strong Raman coherence. However, the broad-bandwidth fs pulses also excite other molecular

W. D. Kulatilaka; J. R. Gord; S. Roy

2011-01-01

348

A versatile femtosecond stimulated Raman spectroscopy setup with tunable pulses in the visible to near infrared  

SciTech Connect

We demonstrate a versatile and efficient setup to perform femtosecond stimulated Raman spectroscopy (FSRS). Technical innovations are implemented to achieve the wavelength tunability for both the picosecond narrowband Raman pump pulse and femtosecond broadband Raman probe pulse. Using a simplified one-grating scheme in a home-built second harmonic bandwidth compressor followed by a two-stage noncollinear optical parametric amplifier, we tune the Raman pump pulse from ca. 480 to 750?nm. To generate the suitable Raman probe pulse in tandem, we rely on our recently demonstrated broadband up-converted multicolor array technique that readily provides tunable broadband laser sidebands across the visible to near-infrared range. This unique setup has unparalleled flexibility for conducting FSRS. We measure the ground-state Raman spectra of a cyclohexane standard using tunable pump-probe pairs at various wavelengths across the visible region. The best spectral resolution is ?12?cm{sup ?1}. By tuning the pump wavelength closer to the electronic absorption band of a photoacid pyranine in water, we observe the pre-resonantly enhanced Raman signal. The stimulated Raman gain of the 1627?cm{sup ?1} mode is increased by over 15 times.

Zhu, Liangdong [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Liu, Weimin [Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States); Fang, Chong, E-mail: Chong.Fang@oregonstate.edu [Department of Physics, Oregon State University, Corvallis, Oregon 97331 (United States); Department of Chemistry, Oregon State University, Corvallis, Oregon 97331 (United States)

2014-07-28

349

A versatile femtosecond stimulated Raman spectroscopy setup with tunable pulses in the visible to near infrared  

NASA Astrophysics Data System (ADS)

We demonstrate a versatile and efficient setup to perform femtosecond stimulated Raman spectroscopy (FSRS). Technical innovations are implemented to achieve the wavelength tunability for both the picosecond narrowband Raman pump pulse and femtosecond broadband Raman probe pulse. Using a simplified one-grating scheme in a home-built second harmonic bandwidth compressor followed by a two-stage noncollinear optical parametric amplifier, we tune the Raman pump pulse from ca. 480 to 750 nm. To generate the suitable Raman probe pulse in tandem, we rely on our recently demonstrated broadband up-converted multicolor array technique that readily provides tunable broadband laser sidebands across the visible to near-infrared range. This unique setup has unparalleled flexibility for conducting FSRS. We measure the ground-state Raman spectra of a cyclohexane standard using tunable pump-probe pairs at various wavelengths across the visible region. The best spectral resolution is ˜12 cm-1. By tuning the pump wavelength closer to the electronic absorption band of a photoacid pyranine in water, we observe the pre-resonantly enhanced Raman signal. The stimulated Raman gain of the 1627 cm-1 mode is increased by over 15 times.

Zhu, Liangdong; Liu, Weimin; Fang, Chong

2014-07-01

350

An all-silicon Raman laser.  

PubMed

The possibility of light generation and/or amplification in silicon has attracted a great deal of attention for silicon-based optoelectronic applications owing to the potential for forming inexpensive, monolithic integrated optical components. Because of its indirect bandgap, bulk silicon shows very inefficient band-to-band radiative electron-hole recombination. Light emission in silicon has thus focused on the use of silicon engineered materials such as nanocrystals, Si/SiO2 superlattices, erbium-doped silicon-rich oxides, surface-textured bulk silicon and Si/SiGe quantum cascade structures. Stimulated Raman scattering (SRS) has recently been demonstrated as a mechanism to generate optical gain in planar silicon waveguide structures. In fact, net optical gain in the range 2-11 dB due to SRS has been reported in centimetre-sized silicon waveguides using pulsed pumping. Recently, a lasing experiment involving silicon as the gain medium by way of SRS was reported, where the ring laser cavity was formed by an 8-m-long optical fibre. Here we report the experimental demonstration of Raman lasing in a compact, all-silicon, waveguide cavity on a single silicon chip. This demonstration represents an important step towards producing practical continuous-wave optical amplifiers and lasers that could be integrated with other optoelectronic components onto CMOS-compatible silicon chips. PMID:15635371

Rong, Haisheng; Liu, Ansheng; Jones, Richard; Cohen, Oded; Hak, Dani; Nicolaescu, Remus; Fang, Alexander; Paniccia, Mario

2005-01-20

351

Trace Element-Isotope Geochemistry of Impact Breccia, Target Basalts and Laser Raman Spectroscopy of Shocked Plagioclase from Lonar Crater, India  

NASA Astrophysics Data System (ADS)

Trace element and isotopic data indicate Archean basement component in the impact breccia of the Deccan basalt-hosted Lonar Crater. Raman spectral study of Lonar and Manicouagan maskelynites indicate different modes of origin of maskelynites.

Chakrabarti, R.; Basu, A. R.; Peterson, J.

2006-03-01

352

Trace Element-Isotope Geochemistry of Impact Breccia, Target Basalts and Laser Raman Spectroscopy of Shocked Plagioclase from Lonar Crater, India  

Microsoft Academic Search

Trace element and isotopic data indicate Archean basement component in the impact breccia of the Deccan basalt-hosted Lonar Crater. Raman spectral study of Lonar and Manicouagan maskelynites indicate different modes of origin of maskelynites.

R. Chakrabarti; A. R. Basu; J. Peterson

2006-01-01

353

ULTRAINTENSE AND ULTRASHORT LASER PULSES FROM RAMAN AMPLIFICATION IN PLASMA FOR LASER-PLASMA ACCELERATORS  

E-print Network

ULTRAINTENSE AND ULTRASHORT LASER PULSES FROM RAMAN AMPLIFICATION IN PLASMA FOR LASER-PLASMA trapping effect in the Raman pulse amplification in plasma. An ultraintense and ultrashort laser pulse (RBS) in plasmas to amplify laser pulses (Fig. 1)is attracting the interests of many people

Wurtele, Jonathan

354

Near-infrared Raman spectroscopy for colonic cancer diagnosis  

NASA Astrophysics Data System (ADS)

This study evaluated the diagnostic ability of near-infrared (NIR) Raman spectroscopy for identifying the malignant tumors from normal and benign tissues in the colon. In this work, a rapid NIR Raman system was utilized for tissue Raman studies. A total of 105 colonic specimens were used for Raman studies, including 41 normals, 18 polyps (benign), and 46 malignant tumors (22 of moderately differentiated adenocarcinomas and 24 of poorly differentiated adenocarcinomas). 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 and malignant tumor tissue. The diagnostic algorithm using the Raman intensity ratios of I1085/1445 vs. I1002/1445 can yield a diagnostic sensitivity of 100% and specificity of 96.6% for differentiation between between normal, benign and malignant colonic tissue. This work demonstrates that NIR Raman spectroscopy technique has a significant potential for the noninvasive diagnosis of colon cancer in vivo based on the evaluation of changes of molecular vibrations of biomolecules in tissue.

Huang, Zhiwei; Zheng, Wei; Colin, Sheppard

2005-08-01

355

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

356

UV Resonant Raman Spectrometer with Multi-Line Laser Excitation  

NASA Technical Reports Server (NTRS)

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

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

2013-01-01

357

Studies of Minerals, Organic and Biogenic Materials through Time-Resolved Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

A compact remote Raman spectroscopy system was developed at NASA Langley Research center and was previously demonstrated for its ability to identify chemical composition of various rocks and minerals. In this study, the Raman sensor was utilized to perform time-resolved Raman studies of various samples such as minerals and rocks, Azalea leaves and a few fossil samples. The Raman sensor utilizes a pulsed 532 nm Nd:YAG laser as excitation source, a 4-inch telescope to collect the Raman-scattered signal from a sample several meters away, a spectrograph equipped with a holographic grating, and a gated intensified CCD (ICCD) camera system. Time resolved Raman measurements were carried out by varying the gate delay with fixed short gate width of the ICCD camera, allowing measurement of both Raman signals and fluorescence signals. Rocks and mineral samples were characterized including marble, which contain CaCO3. Analysis of the results reveals the short (approx.10-13 s) lifetime of the Raman process, and shows that Raman spectra of some mineral samples contain fluorescence emission due to organic impurities. Also analyzed were a green (pristine) and a yellow (decayed) sample of Gardenia leaves. It was observed that the fluorescence signals from the green and yellow leaf samples showed stronger signals compared to the Raman lines. Moreover, it was also observed that the fluorescence of the green leaf was more intense and had a shorter lifetime than that of the yellow leaf. For the fossil samples, Raman shifted lines could not be observed due the presence of very strong short-lived fluorescence.

Garcia, Christopher S.; Abedin, M. Nurul; Ismail, Syed; Sharma, Shiv K.; Misra, Anupam K.; Nyugen, Trac; Elsayed-Ali, hani

2009-01-01

358

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

NASA Technical Reports Server (NTRS)

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

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

2008-01-01

359

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

360

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

361

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

SciTech Connect

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

Molesky, Brian P.; Giokas, Paul G.; Guo, Zhenkun; Moran, Andrew M., E-mail: ammoran@email.unc.edu [Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 (United States)

2014-09-21

362

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

PubMed

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

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

2014-09-21

363

Rapid detection of chlorpyrifos pesticide residue concentration in agro-product using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Different chemicals are sprayed in fruits and vegetables before and after harvest for better yield and longer shelf-life of crops. Cases of pesticide poisoning to human health are regularly reported due to excessive application of such chemicals for greater economic benefit. Different analytical technologies exist to detect trace amount of pesticides in fruits and vegetables, but are expensive, sample destructive, and require longer processing time. This study explores the application of Raman spectroscopy for rapid and non-destructive detection of pesticide residue in agricultural products. Raman spectroscopy with laser module of 785 nm was used to collect Raman spectral information from the surface of Gala apples contaminated with different concentrations of commercially available organophosphorous (48% chlorpyrifos) pesticide. Apples within 15 days of harvest from same orchard were used in this study. The Raman spectral signal was processed by Savitzky-Golay (SG) filter for noise removal, Multiplicative Scatter Correction (MSC) for drift removal and finally polynomial fitting was used to eliminate the fluorescence background. The Raman spectral peak at 677 cm-1 was recognized as Raman fingerprint of chlorpyrifos. Presence of Raman peak at 677 cm-1 after fluorescence background removal was used to develop classification model (presence and absence of pesticide). The peak intensity was correlated with actual pesticide concentration obtained using Gas Chromatography and MLR prediction model was developed with correlation coefficient of calibration and validation of 0.86 and 0.81 respectively. Result shows that Raman spectroscopy is a promising tool for rapid, real-time and non-destructive detection of pesticide residue in agro-products.

Dhakal, Sagar; Peng, Yankun; Li, Yongyu; Chao, Kuanglin; Qin, Jianwei; Zhang, Leilei; Xu, Tianfeng

2014-05-01

364

Raman and Infrared Spectroscopy of Pyridine under High Pressure  

SciTech Connect

We report the structural transitions of pyridine as a function of pressure up to 26 GPa using in situ Raman spectroscopy and infrared absorption spectroscopy. By monitoring changes in the Raman shifts in the lattice region as well as the band profiles in both Raman and IR spectra, a liquid-to-solid transition at 1 GPa followed by solid-to-solid transitions at 2, 8, 11, and 16 GPa were observed upon compression. These transitions were found to be reversible upon decompression from 22 GPa. A further chemical transformation was observed when compressed beyond 22 GPa as evidenced by the substantial and irreversible changes in the Raman and infrared spectra, which could be attributed to the destruction of the ring structure. The observed transformations in pyridine were also compared to those for benzene. The similar transition sequence with well-aligned transition pressures suggests that these isoelectronic aromatics may have similar structures and stabilities under high pressure.

Zhuravlev, K.; Traikov, K; Dong, Z; Xie, S; Song, Y; Liu, Z

2010-01-01

365

Monitoring the influence of antibiotic exposure using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Here we report on combination of the data obtained from MICs (minimum inhibitory concentrations) with infor- mation of microoragnisms fingerprint provided by Raman spectroscopy. In our feasibility study we could follow mechanisms of the bacteriostatic versus bactericidal action on biofilm-positive Staphylococcus epidermidis simply by monitoring Raman bands corresponding to DNA translating the changes introduced by selected antibiotics. The Raman spectra of Staphylococcus epidermidis treated with a bacteriostatic agent show little effect on DNA which is in contrast with the action of a bactericidal agent where decreased in dedicated Raman spectra signal strength suggests DNA fragmentation. Moreover, we demonstrate that Raman tweezers are indeed able to distinguish strains of biofilm-forming (biofilm-positive) and biofilm-negative Staphylococcus epidermidis strains using principal component analysis (PCA).

Samek, Ota; Zemanek, Pavel; Bernatova, Silvie; Jezek, Jan; Sery, Mojmir; Jakl, Petr; Siler, Martin; Ruzicka, Filip

2014-03-01

366

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

2014-06-01

367

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

2011-02-01

368

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

NASA Astrophysics Data System (ADS)

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.

Kavkler, Katja; Demšar, Andrej

2011-02-01

369

Method And System For Examining Biological Materials Using Low Power Cw Excitation Raman Spectroscopy.  

DOEpatents

A method and system for examining biological materials using low-power cw excitation Raman spectroscopy. In accordance with the teachings of the invention, a low-power continuous wave (cw) pump laser beam and a low-power cw Stokes (or anti-Stokes) probe laser beam simultaneously illuminate a biological material and traverse the biological material in collinearity. The pump beam, whose frequency is varied, is used to induce Raman emission from the biological material. The intensity of the probe beam, whose frequency is kept constant, is monitored as it leaves the biological material. When the difference between the pump and probe excitation frequencies is equal to a Raman vibrational mode frequency of the biological material, the weak probe signal becomes amplified by one or more orders of magnitude (typically up to about 10.sup.4 -10.sup.6) due to the Raman emission from the pump beam. In this manner, by monitoring the intensity of the probe beam emitted from the biological material as the pump beam is varied in frequency, one can obtain an excitation Raman spectrum for the biological material tested. The present invention may be applied to in the in vivo and/or in vitro diagnosis of diabetes, heart disease, hepatitis, cancers and other diseases by measuring the characteristic excitation Raman lines of blood glucose, cholesterol, serum glutamic oxalacetic transaminase (SGOT)/serum glutamic pyruvic tansaminase (SGPT), tissues and other corresponding Raman-active body constituents, respectively. For example, it may also be used to diagnose diseases associated with the concentration of Raman-active constituents in urine, lymph and saliva It may be used to identify cancer in the breast, cervix, uterus, ovaries and the like by measuring the fingerprint excitation Raman spectra of these tissues. It may also be used to reveal the growing of tumors or cancers by measuring the levels of nitric oxide in tissue.

Alfano, Robert R. (Bronx, NY); Wang, Wubao (Flushing, NY)

2000-11-21

370

Plasmon-assisted chemical reactions revealed by high-vacuum tip-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Tip-enhanced Raman spectroscopy (TERS) is the technique that combines the nanoscale spatial resolution of a scanning probe microscope and the highly sensitive Raman spectroscopy enhanced by the surface plasmons. It is suitable for chemical analysis at nanometer scale. Recently, TERS exhibited powerful potential in analyzing the chemical reactions at nanoscale. The high sensitivity and spatial resolution of TERS enable us to learn the reaction processes more clearly. More importantly, the chemical reaction in TERS is assisted by surface plasmons, which provides us an optical method to manipulate the chemical reactions at nanoscale. Here using our home-built high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) setup, we successfully observed the plasmon-assisted molecule dimerization and dissociation reactions. In HV-TERS system, under laser illumination, 4-nitrobenzenethiol (4NBT) molecules can be dimerized to p,p'-dimercaptoazobenzene (DMAB), and dissociation reaction occurs for malachite green (MG) molecules. Using our HV-TERS setup, the dynamic processes of the reactions are clearly revealed. The chemical reactions can be manipulated by controlling the plasmon intensity through changing the power of the incident laser, the tunneling current and the bias voltage. We also investigated the role of plasmonic thermal effect in the reactions by measuring both the Stokes and anti- Stokes Raman peaks. Our findings extend the applications of TERS, which can help to study the chemical reactions and understand the dynamic processes at single molecular level, and even design molecules by the plasmon-assisted chemical reactions.

Lu, Shuaicheng; Sheng, Shaoxiang; Zhang, Zhenglong; Xu, Hongxing; Zheng, Hairong

2014-08-01

371

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

SciTech Connect

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

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

2008-08-11

372

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

373

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

NASA Astrophysics Data System (ADS)

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. Antarctic desert analoges of potential early Mars habitats support localized anaerobic photosynthetic bacteria and widespread cyanobacteria containing chlorophyll as a primary pigment. Chlorophyll and accessory pigments (e.g. phycocyanin) autofluoresce at visible wavelengths (e.g. 530 nm). Although valuable for epifluorescence microscopy, this interferes with Raman spectra by producing curved baselines and instrument saturation. Fourier Transform Raman spectroscopy (FTRS) with near-IR excitation avoids most fluorescence while producing distinct and unique spectra for a wide range of wavenumbers. These spectra identify key moieties, such as the porphyrin nucleus of chlorophyll, which can be detected in whole communities from deserts with features common to potential habitats of early Mars.

Schoen, C. H.; Dickensheets, D. L.

2000-07-01

374

Subframe Burst Gating for Raman Spectroscopy in Combustion  

NASA Technical Reports Server (NTRS)

We describe an architecture for spontaneous Raman scattering utilizing a frame-transfer CCD sensor operating in a subframe burst-gating mode to realize time-resolved combustion diagnostics. The technique permits all-electronic optical gating with microsecond shutter speeds 5 J.Ls) without compromising optical throughput or image fidelity. When used in conjunction with a pair of orthogonally polarized excitation lasers, the technique measures single-shot vibrational Raman scattering that is minimally contaminated by problematic optical background noise.

Kojima, Jun; Fischer, David; Nguyen, Quang-Viet

2010-01-01

375

Modulated Fourier Transform Raman Fiber-Optic Spectroscopy  

NASA Technical Reports Server (NTRS)

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

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

2000-01-01

376

Raman and surface-enhanced Raman spectroscopy of tempyo spin labelled ovalbumin  

Microsoft Academic Search

Tempyo labelled ovalbumin at different pH values was prepared and investigated using Raman and SERS spectroscopy. Raman spectra of tempyo labelled ovalbumin in the pH range from 6.7 to 11 were compared to those of the corresponding free ovalbumin. In the basic pH range from 6.7 to 11 the molecular conformation was found to be unaffected by the tempyo presence.

S Cavalu; N Leopold; R Petry; W Kiefer

2001-01-01

377

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

NASA Astrophysics Data System (ADS)

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

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

2014-03-01

378

The use of four-photon Raman spectroscopy for the remote sensing of natural objects  

NASA Technical Reports Server (NTRS)

The results of the laboratory simulation of optical Kerr effect/Raman spectroscopy for the purpose of remote sensing are presented. The experimental setup is described, and measurements of the vibrational spectra of various liquids obtained. Attention is paid to the possibility of using the proposed method to detect trace hydrocarbons in water, and the spectrum of petroleum is obtained. Full-scale measurements using a laser spectrometer were made on the Black Sea.

Bunkin, A. F.; Galumyan, A. S.; Zhumanov, Kh. A.; Maltsev, D. V.

1988-01-01

379

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

380

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

381

Two-dimensional Raman-terahertz spectroscopy of water  

PubMed Central

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

Savolainen, Janne; Ahmed, Saima; Hamm, Peter

2013-01-01

382

Characterization of oil-producing microalgae using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

Raman spectroscopy offers a powerful alternative analytical method for the detection and identification of lipids/oil in biological samples, such as algae and fish. Recent research in the authors' groups, and experimental data only very recently published by us and a few other groups suggest that Raman spectroscopy can be exploited in instances where fast and accurate determination of the iodine value (associated with the degree of lipid unsaturation) is required. Here the current status of Raman spectroscopy applications on algae is reviewed, and particular attention is given to the efforts of identifying and selecting oil-rich algal strains for the potential mass production of commercial biofuels and for utilization in the food industry.

Samek, O.; Zemánek, P.; Jonáš, A.; Telle, H. H.

2011-10-01

383

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

PubMed

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

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

2014-09-23

384

Actively Q-switched Raman fiber laser  

NASA Astrophysics Data System (ADS)

A new scheme providing actively Q-switched operation of a Raman fiber laser (RFL) has been proposed and tested. The RFL consists of a 1?km single-mode fiber with a switchable loop mirror at one end and an angled cleaved output end. An 1080?nm pulse with microsecond duration is generated at the output by means of acousto-optic switching of the mirror at ~30?kHz in the presence of 6?W backward pumping at 1030?nm. In the proposed scheme, the generated pulse energy is defined by the pump energy distributed along the passive fiber, which amounts to 30??J in our case. The available pump energy may be increased by means of fiber lengthening. Pulse shortening is also expected.

Kuznetsov, A. G.; Podivilov, E. V.; Babin, S. A.

2015-03-01

385

Nd:Glass-Raman laser for water vapor dial  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

386

Surfaced-enhanced Raman spectroscopy of nasopharyngeal carcinoma cell using gol nanoparticles  

Microsoft Academic Search

The surface-enhanced Raman scattering (SERS) spectroscopy and normal Raman spectroscopy of single living human nasopharyngeal carcinoma cells(CNE-1) were tested and analyzed by gold nanoparticles incubation into cells. The characteristic Raman bands in the SERS spectra of living cells were tentatively assigned. Six obvious Raman bands (718, 1001, 1123, 1336, 1446, 1660 cm-1) were observed in the normal Raman spectroscopy of

Rong Chen; Hao Huang; Li-Qing Sun; Jian-Ji Pan; Wei-Wei Chen; Ying Su; Shang-Yuan Feng; Yong-Zeng Li

2010-01-01

387

Analysis of hydrocarbon fuel properties by means of Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

Flatley, Martin W.

388

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

E-print Network

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

Katz, Ori; Grinvald, Eran; Silberberg, Yaron

2010-01-01

389

Laser spectroscopy at accelerator facilities  

SciTech Connect

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

Berry, H.G.

1989-01-01

390

Single-molecule detection of yeast cytochrome c by Surface-Enhanced Raman Spectroscopy  

E-print Network

Single-molecule detection of yeast cytochrome c by Surface-Enhanced Raman Spectroscopy Ines Delfino are enhanced in presence of nanostructured metal surfaces [8] has dramatically boosted Raman spectroscopy allowed a very wide use of Surface- Enhanced Raman Scattering (SERS) and Surface-Enhanced Resonance Raman

Tuscia, Università Degli Studi Della

391

Mechanism of exciplex formation between Cu-porphyrin and calf-thymus DNA as revealed by saturation resonance Raman spectroscopy  

Microsoft Academic Search

The excited-state complex (exciplex) formation that results from the photoinduced interaction of water-soluble cationic copper(II) 5,10,15,20-tetrakis[4-(N-methylpyridyl)]porphyrin [Cu(TMpy-P4)] with calf-thymus DNA has been studied in detail by resonance Raman (RR) spectroscopy using both ~10 ns and ~50 ps laser pulses. The obtained Raman saturation dependences were simulated using the rate equations approach on the basis of two different models. The first

A. G. Shvedko; S. G. Kruglik; V. V. Ermolenkov; V. A. Orlovich; P.-Y. Turpin; J. Greve; C. Otto

1999-01-01

392

JOURNAL OF RAMAN SPECTROSCOPY J. Raman Spectrosc. 31, 171176 (2000)  

E-print Network

Wiley & Sons, Ltd. INTRODUCTION The formation of an adequate dentin­adhesive bond depends upon diffusion spectroscopy were used to investigate the influence of surface treatment on the diffusion of a dental adhesive into dentin. The commercial dentin adhesive Scotchbond MultiPurpose Plus (3M) was placed on coronal dentin

Kruger, Michael - Department of Physics, University of Missouri

393

Temperature dependent Raman spectroscopy of chemically derived graphene  

NASA Astrophysics Data System (ADS)

Reduced graphite oxide (GO) has shown promise as a scalable alternative to mechanically exfoliated specimens. Although many measurements show that reduced GO has properties approaching those of pristine graphene, it has been difficult to quantify the extent to which the graphitic network is restored upon reduction. Raman spectroscopy is widely used for the characterization of mechanically exfoliated graphene, but has not been fully explored for reduced GO. In this work, hydrazine suspensions of reduced GO are deposited on micro-hot-plates and examined over a range of temperatures by Raman spectroscopy. The work highlights the benefits of solution processing.

Allen, Matthew J.; Fowler, Jesse D.; Tung, Vincent C.; Yang, Yang; Weiller, Bruce H.; Kaner, Richard B.

2008-11-01

394

Condition Assessment of Kevlar Composite Materials Using Raman Spectroscopy  

NASA Technical Reports Server (NTRS)

This viewgraph presentation includes the following main concepts. Goal: To evaluate Raman spectroscopy as a potential NDE tool for the detection of stress rupture in Kevlar. Objective: Test a series of strand samples that have been aged under various conditions and evaluate differences and trends in the Raman response. Hypothesis: Reduction in strength associated with stress rupture may manifest from changes in the polymer at a molecular level. If so, than these changes may effect the vibrational characteristics of the material, and consequently the Raman spectra produced from the material. Problem Statement: Kevlar composite over-wrapped pressure vessels (COPVs) on the space shuttles are greater than 25 years old. Stress rupture phenomena is not well understood for COPVs. Other COPVs are planned for hydrogen-fueled vehicles using Carbon composite material. Raman spectroscopy is being explored as an non-destructive evaluation (NDE) technique to predict the onset of stress rupture in Kevlar composite materials. Test aged Kevlar strands to discover trends in the Raman response. Strength reduction in Kevlar polymer will manifest itself on the Raman spectra. Conclusions: Raman spectroscopy has shown relative changes in the intensity and FWHM of the 1613 cm(exp -1) peak. Reduction in relative intensity for creep, fleet leader, and SIM specimens compared to the virgin strands. Increase in FWHM has been observed for the creep and fleet leader specimens compared to the virgin strands. Changes in the Raman spectra may result from redistributing loads within the material due to the disruption of hydrogen bonding between crystallites or defects in the crystallites from aging the Kevlar strands. Peak shifting has not been observed to date. Analysis is ongoing. Stress measurements may provide a tool in the short term.

Washer, Glenn; Brooks, Thomas; Saulsberry, Regor

2007-01-01

395

Dengue blood analysis by Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

396

Profiling the near field of nanoshells using surface enhanced Raman spectroscopy and fluorescence spectroscopy  

Microsoft Academic Search

Plasmon resonances in metal nanoparticles control the far field and near field optical properties of these metallic structures. The enhanced electromagnetic near field is strongest at the surface of the nanoparticles and rapidly decays away from the surface. This enhanced near field is exploited in surface enhanced spectroscopies including Surface Enhanced Raman Spectroscopy (SERS) and Metal Enhanced Fluorescence Spectroscopy (MEFS).

Surbhi Lal

2006-01-01

397

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

NASA Astrophysics Data System (ADS)

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

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

2013-04-01

398

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

399

Stimulated Raman Scattering Microscopy with a Robust Fibre Laser Source  

PubMed Central

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

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

2014-01-01

400

Monitoring of aqueous humor metabolites using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

1994-05-01

401

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

402

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

E-print Network

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

Floreano, Dario

403

ForPeerReview Surface Enhanced Raman spectroscopy of tiopronin [N-(2-  

E-print Network

ForPeerReview Surface Enhanced Raman spectroscopy of tiopronin [N-(2- Mercaptopropionyl) glycine #12;ForPeerReview 1 Surface Enhanced Raman spectroscopy of tiopronin [N-(2-Mercaptopropionyl) glycine with gold nanoparticles for surface enhanced Raman spectroscopy (SERS) studies of hemoglobin. Gold

Hewitt, Kevin

404

A Unified Approach to Surface-Enhanced Raman Spectroscopy John R. Lombardi* and Ronald L. Birke  

E-print Network

A Unified Approach to Surface-Enhanced Raman Spectroscopy John R. Lombardi* and Ronald L. Birke present a unified expression for surface-enhanced Raman spectroscopy (SERS). The expression contains it is responsible for surface-enhanced resonance Raman spectroscopy. We examine this expression in various limits

Lombardi, John R.

405

Gold nanorods 3D-supercrystals as surface enhanced Raman scattering spectroscopy substrates for the  

E-print Network

Gold nanorods 3D-supercrystals as surface enhanced Raman scattering spectroscopy substrates of nanorods render these systems excellent surface enhanced Raman scattering spectroscopy substrates spectral range. Surface enhanced Raman scattering (SERS) spectroscopy is not only one of the most sensitive

Zubarev, Eugene

406

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

E-print Network

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

North, Elizabeth W.

407

JOURNAL OF RAMAN SPECTROSCOPY, VOL. 27, 549-554 (1996) Structure Characterizationof W03/Zr02  

E-print Network

JOURNAL OF RAMAN SPECTROSCOPY, VOL. 27, 549-554 (1996) Structure Characterizationof W03/Zr02 Catalystsby Raman Spectroscopy Biying Zhao,* Xianping Xu, Jinming Gao, Qiang Fu and Youqi Tang Institute and quantitative Raman spectroscopy. The resultsshowed that ZrO, in WO,/ZrO, obtained from crystallized Zr

Gao, Jinming

408

Characterisation of transmission Raman spectroscopy for rapid quantitative analysis of intact multi-component pharmaceutical capsules  

Microsoft Academic Search

A detailed characterisation of the performance of transmission Raman spectroscopy was performed from the standpoint of rapid quantitative analysis of pharmaceutical capsules using production relevant formulations comprising of active pharmaceutical ingredient (API) and 3 common pharmaceutical excipients. This research builds on our earlier studies that identified the unique benefits of transmission Raman spectroscopy compared to conventional Raman spectroscopy. These include

Michael D. Hargreaves; Neil A. Macleod; Mark R. Smith; Darren Andrews; Stephen V. Hammond; Pavel Matousek

2011-01-01

409

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

410

1480 nm two-cascaded highly efficient Raman fiber laser  

Microsoft Academic Search

Summary form only given. Lasers based on high P2O5-doped fibers can potentially have a higher efficiency than Raman fiber lasers (RFL) based on standard Ge-doped fibers. An increase of phosphorus content in the fiber core gives rise to an increase of the Raman gain coefficient. Despite a rise of optical losses, heavily P2O5-doped fibers enable one to develop extremely efficient

I. A. Bufetov; M. M. Bubnov; Y. V. Larionov; M. A. Melkoumov; A. A. Rybaltovsky; S. L. Semjonov; E. M. Dianov

2002-01-01

411

Stimulated Raman Side Scattering in Laser Wakefield Acceleration  

SciTech Connect

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

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

2010-07-16

412

Predicting tenderness of fresh ovine semimembranosus using Raman spectroscopy.  

PubMed

A hand held Raman probe was used to predict shear force (SF) of fresh lamb m. semimembranosus (topside). Eighty muscles were measured at 1 day PM and after a further 4 days ageing (5 days PM). At 1 day PM sarcomere length (SL) and particle size (PS) were measured and at 5 days PM, SF, PS, cooking loss (CL) and pH were also measured. SF values were regressed against Raman spectra using partial least squares regression and against traditional predictors (e.g. SL) using linear regression. The best prediction of SF used spectra at 1 day PM which gave a root mean square error of prediction (RMSEP) of 11.5 N (Null = 13.2) and the squared correlation between observed and cross validated predicted values (R(2)cv) was 0.27. Prediction of SF based on the traditional predictors had smaller R(2) values than using Raman spectra justifying further study on Raman spectroscopy. PMID:24785653

Fowler, Stephanie M; Schmidt, Heinar; van de Ven, Remy; Wynn, Peter; Hopkins, David L

2014-08-01

413

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. PMID:22087048

Rajapaksa, I.; Kumar Wickramasinghe, H.

2011-01-01

414

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

415

Electromigrated Nanoscale Gaps for Surface-Enhanced Raman Spectroscopy  

Microsoft Academic Search

Single-molecule detection with chemical specificity is a powerful and much desired tool for biology, chemistry, physics, and sensing technologies. Surface-enhanced spectroscopies enable single molecule studies, yet reliable substrates of adequate sensitivity are in short supply. We present a simple, scaleable substrate for surface-enhanced Raman spectroscopy (SERS) incorporating nanometer-scale electromigrated gaps between extended electrodes. Molecules in the nanogap active regions exhibit

Daniel R. Ward; Nathaniel K. Grady; Carly S. Levin; Naomi J. Halas; Yanpeng Wu; Peter Nordlander; Douglas Natelson

2007-01-01

416

Raman spectroscopy for in-situ monitoring of electrode processes  

SciTech Connect

The theoretical and experimental applications of Raman spectroscopic techniques to the study of battery electrode processes are described. In particular, the potential of Raman spectroscopy as an in-situ analytical tool for the characterization of the structure and composition of electrode surface layers at electrode-electrolyte interfaces during electrolysis is examined. It is anticipated that this understanding of the battery electrode processes will be helpful in designing battery active material with improved performance. The applications of Raman spectroscopy to the in-situ study of electrode processes has been demonstrated in a few selected areas, including: (1) the anodic corrosion of lead in sulfuric acid and (2) the anodization and sulfation of tetrabasicleadsulfate in sulfuric acid. Preliminary results on the anodization of iron and on the electrochemical behavior of nickel positive-electrode active material in potassium hydroxide electrolytes are presented in the Appendix.

Varma, R; Cook, G M; Yao, N P

1982-04-01

417

Surface enhanced Raman spectroscopy of aromatic compounds on silver nanoclusters  

NASA Astrophysics Data System (ADS)

Surface enhanced Raman spectroscopy (SERS) has been used to characterize multilayers of three different aromatic compounds in the proximity of silver nanoclusters. SERS of mercapto benzoic acid (MBA), which adsorbs onto the silver nanoclusters through the sulfur moiety, exhibits frequency shifts in comparison to the Raman spectrum of crystalline MBA. Conversely, benzoic acid and benzophenone that adsorb through the oxygen species lack these frequency shifts, and show only a typical SERS enhancement. We employed X-ray photoelectron spectroscopy (XPS), to probe the nature of the binding between the silver and the three different aromatic compounds. Thereafter, we assigned the major Raman peaks of all three molecules to specific molecular vibrations. Overall, this enables us to determine the origin of the observed shifts in the SERS spectrum of MBA and similar molecules.

Fleger, Y.; Mastai, Y.; Rosenbluh, M.; Dressler, D. H.

2009-03-01

418

Analysis of milk by FT-Raman spectroscopy.  

PubMed

Fat, protein, carbohydrates and dry matter were quantified in commercial bovine milk samples, with the relative standard errors of prediction (RSEP) in the 3.4-6.1% range, using the partial least squares (PLS) method based on Raman spectra of liquid milk samples. Results of a better quality were obtained from a PLS model derived from IR spectra registered using single reflection ATR diamond accessory, which yielded RSEP values of 2.4-4.4%. The data indicated IR single reflection ATR spectroscopy and Raman spectroscopy in combination with multivariate modelling using the PLS method, allowed for the reliable, simultaneous quantitative determination of macronutrients in milk. The low signal to noise ratio of Raman spectra affects the quality of fat quantification especially for strongly defatted milk samples. PMID:25863403

Mazurek, Sylwester; Szostak, Roman; Czaja, Tomasz; Zachwieja, Andrzej

2015-06-01

419

Raman-spectroscopy-based biosensing for applications in ophthalmology  

NASA Astrophysics Data System (ADS)

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

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

2013-05-01

420

Polarized micro Raman scattering spectroscopy for curved edges of epitaxial graphene  

NASA Astrophysics Data System (ADS)

This letter performed polarized microscopic laser Raman scattering spectroscopy on the curved edges of transferred epitaxial graphene on SiO2/Si. The intensity ratio between the parallel and perpendicular polarized D band is evolved, providing a spectroscopy-based technique to probe the atomic-scale edge structures in graphene. A detailed analysis procedure for non-ideal disordered curved edges of graphene is developed combining the atomic-scale zigzag and armchair edge structures along with some point defects. These results could provide valuable information of the realistic edges of graphene at the atomic-scale that can strongly influence the performance of graphene-based nanodevices.

Islam, Md. Sherajul; Bhuiyan, A. G.; Tanaka, S.; Makino, T.; Hashimoto, A.

2014-12-01

421

Single Molecule Tip Enhanced Raman Spectroscopy NSF Grant # 1121262  

E-print Network

MRSEC Single Molecule Tip Enhanced Raman Spectroscopy NSF Grant # 1121262 Matthew D. Sonntag1, it can "see" one single molecule at a time, this was carried out by studying the vibrational signature fingerprint that allows molecule identification. J. Phys. Chem. C, 2012, 116 (1), pp 478­483 · R6G-d4 · R6G-d0

Shahriar, Selim

422

Stress Analysis of SiC MEMS Using Raman Spectroscopy  

NASA Astrophysics Data System (ADS)

During the fabrication of Micro-Electro-Mechanical Systems (MEMS), residual stress is often induced in the thin films that are deposited to create these systems. These stresses can cause the device to fail due to buckling, curling, or fracture. Industry is looking for ways to characterize the stress during the deposition of thin films in order to reduce or eliminate device failure. Micro-Raman spectroscopy has been successfully used to characterize poly-Si MEMS devices made with the MUMPS® process. Raman spectroscopy was selected because it is nondestructive, fast and has the potential for in situ stress monitoring. This research attempts to use Raman spectroscopy to analyze the stress in SiC MEMS made with the MUSiC® process. Raman spectroscopy is performed on 1-2-micron-thick SiC thin films deposited on silicon, silicon nitride, and silicon oxide substrates. The most common poly-type of SiC found in thin film MEMS made with the MUSiC® process is 3C-SiC. Research also includes baseline spectra of 6H, 4H, and 15R poly-types of bulk SiC.

Ness, Stanley J.; Marciniak, M. A.; Lott, J. A.; Starman, L. A.; Busbee, J. D.; Melzak, J. M.

2003-03-01

423

Postdoc Position in Microfluidics and Single Cell Raman Spectroscopy  

E-print Network

Postdoc Position in Microfluidics and Single Cell Raman Spectroscopy Department of Microbial and Environmental Microfluidics Group (http://web.mit.edu/romanstocker) Department of Civil & Environmental (junior or senior) with strong expertise in microfluidics and an interest in applying it to microbial

Horn, Matthias

424

Imaging EGFR distribution using surface-enhanced Raman spectroscopy  

Microsoft Academic Search

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

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

2009-01-01

425

Raman Spectroscopy for the Biochemical Characterization of Bacteria Khozima Hamasha  

E-print Network

Raman Spectroscopy for the Biochemical Characterization of Bacteria Khozima Hamasha Department division protein DivIVA) has on M. tuberculosis, which could be key to treating tuberculosis. The phosphorylation of Wag31 caused significant differences in the quantity of proteins and lipid II which were

Rehse, Steven J.

426

Performing tip-enhanced Raman spectroscopy in liquids  

Microsoft Academic Search

Many outstanding questions in biology and medicine require analytical tools that provide imaging and chemical information with high spatial resolution. Tip-enhanced Raman spectroscopy (TERS) has been shown to allow both topographic and label-free chemical information to be obtained with a lateral resolution of approximately 20 - 50 nm, but has been performed only in air or ultrahigh vacuum until now.

Thomas Schmid; Boon-Siang Yeo; Grace Leong; Johannes Stadler; Renato Zenobi

2009-01-01

427

Raman spectroscopy of ion-irradiated astrophysically relevant materials  

Microsoft Academic Search

Solid objects in space (interstellar grains, comets, interplanetary dust particles, etc.) are continuously exposed to energetic processes, such as cosmic ion irradiation, that influence their evolution. In this paper we present an experimental study, carried out by Raman spectroscopy, of the effects induced by ion irradiation on frozen ices and refractory materials. If the irradiated ice mixture contains a relevant

G. A. Baratta; R. Brunetto; G. Leto; M. E. Palumbo; F. Spinella; G. Strazzulla

2008-01-01

428

Surface-enhanced Raman spectroscopy of surfactants on silver electrodes  

Microsoft Academic Search

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

Soncheng. Sun; Ronald L. Birke; John R. Lombardi

1990-01-01

429

Optically addressable selective nanovolume Raman spectroscopy of nanoparticles  

Microsoft Academic Search

We present recent experimental and theoretical advances in the selective nanovolume Raman spectroscopy of nanoparticles. Our setup is based on previously available microspectrometry imaging systems for working in the near-field domain combined with a stigmatic solid immersion lens. By spectrally selecting nanoparticles, we registered the spatial distribution of the emitted photons in x, y, z vectors to determine the position

Han Athalin; Serge Lefrant

2005-01-01

430

Noninvasive blood analysis by tissue-modulated NIR Raman spectroscopy  

Microsoft Academic Search

We present tissue modulated Raman spectroscopy as a technique for noninvasively measuring the concentration of blood analytes in vivo. We present preliminary data used to determine the best methods for analyzing our data. These experiments provide additional proof that we are indeed able to obtain the spectra of human blood in vivo and noninvasively. We discuss differences between our spectra

Joseph Chaiken; William F. Finney; Paul E. Knudson; Karen P. Peterson; Charles M. Peterson; Xiaoke Yang; Ruth S. Weinstock

2001-01-01

431

ACCVD Growth, Raman and Photoluminescence Spectroscopy of Isotopically  

E-print Network

ACCVD Growth, Raman and Photoluminescence Spectroscopy of Isotopically Modified Single, Photoluminescence. PACS: 78.67.Ch, 81.07.De INTRODUCTION For the production technique of single-walled carbon is discussed. Photoluminescence (PL) has been intensively studied for the characterization of SWNTs [6, 7

Maruyama, Shigeo

432

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

NASA Astrophysics Data System (ADS)

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

Brady, John J.; Pellegrino, Paul M.

2013-05-01

433

Histochemical analysis of human coronary artery using near-infrared Raman spectroscopy  

NASA Astrophysics Data System (ADS)

We are developing a method to quantitatively analyze the biochemical composition of human coronary artery in situ using near-infrared Raman spectroscopy. Samples of normal artery (intima/media and adventitia) and noncalcified and calcified plaque from coronary arteries, obtained from explanted recipient hearts during heart transplantation, were illuminated with 830 nm excitation light from a CW Ti:sapphire laser. Raman spectra were collected in seconds using a spectrograph and a cooled, deep-depletion CCD detector, and calibration and background corrections were made. Artery samples in different stages of atherosclerosis exhibited distinct spectral features, providing clear histochemical indicators for characterizing the type and extent of the lesion. Spectra were analyzed by means of a Raman biochemical assay model to determine the relative weight fractions of cholesterols, triacylglycerol, proteins and calcium minerals. Such information, when obtained clinically, promises to be useful in diagnosing and studying human atherosclerosis, its progression and response to drug therapy.

Brennan, James F., III; Roemer, Tjeerd J.; Wang, Yang; Fitzmaurice, Maryann; Lees, Robert S.; Kramer, John R., Jr.; Feld, Michael S.

1995-01-01

434

Conjugated polyenes as chemical probes of life signature: use of Raman spectroscopy to differentiate polyenic pigments.  

PubMed

Polyenes, which are represented by carotenes, carotenoids and conjugated polyenals, are some of the most important targets for astrobiology, because they can provide strong evidence of the presence of organic compounds in the most extreme environments, such as on Mars. Raman spectroscopy has been used as the main analytical tool in the identification of such compounds, for the greatest variety of living species, from microorganisms to animals and plants. However, using only the position of the characteristic Raman bands can lead to errors in tentatively identifying chemicals. In this work, we present a series of observations that can provide a more complete and robust way to analyse the Raman spectrum of a polyenal, in which the position, the intensity, the use of various laser lines for excitation, and the combination of more than one pigment can be considered in the complete analysis. PMID:25368351

Maia, Lenize F; Fernandes, Rafaella F; Lobo-Hajdu, Gisele; de Oliveira, Luiz F C

2014-12-13

435

Measurement of diabetic sugar concentration in human blood using Raman spectroscopy  

NASA Astrophysics Data System (ADS)

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

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

2012-06-01

436

Raman spectroscopy for bacterial identification and characterization  

NASA Astrophysics Data System (ADS)

The main goal of our investigation is to use Raman tweezers technique so that the responce of Raman scattering on microorganisms suspended in liquid media (bacteria, algae and yeast cells in microfluidic chips) can be used to identify different species. The investigations presented here include identification of different bacteria strains (biofilm-positive and biofilm-negative) and yeast cells by using principal component analysis (PCA). The main driving force behind our investigation was a common problem in the clinical microbiology laboratory - how to distinguish between contaminant and invasive isolates. Invasive bacterial/yeast isolates can be assumed to form a biofilm, while isolates which do not form a biofilm can be treated as contaminant. Thus, the latter do not represent an important virulence factor.

Bernatová, Silvie; Samek, Ota; Pilát, Zden?k.; Šerý, Mojmír.; Ježek, Jan; Krzyžánek, Vladislav; Zemánek, Pavel; Ruži?ka, Filip

2012-01-01

437

Near-IR Fourier transform Raman spectroscopy in surgery and medicine: detection of renal stones and bladder cancer  

NASA Astrophysics Data System (ADS)

Tissue diagnosis and characterization are critically important to the development and applications of laser-based therapeutic procedures in urology (viz., laser lithotripsy and bladder cancer treatment