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Sample records for raman scattering imaging

  1. Image formation using stimulated raman scattering gain

    NASA Astrophysics Data System (ADS)

    Bespalov, V. G.; Makarov, E. A.; Stasel'ko, D. I.

    2016-07-01

    Theoretical analysis of the spatial, noise, and energy characteristics of an amplifier has been performed in the mode of spectral and time selection using subnanosecond stimulated Raman Scattering gain of weak echo signals in crystalline active media that are known for high (up to 10-1 cm/MW) gain coefficients. The possibility to reach high gain values has been demonstrated for weak signals from objects at acceptable angular sizes of the field of vision of an amplifier. To provide a signal-to-noise ratio that exceeds unity over the entire field of vision, the number of photons at the input to an amplifier that is required has to exceed the number of its resolution elements. Accurate determination of the possibilities of recording of weak echo signals and quality of images of targets that are obtained using amplifiers under stimulated Raman Scattering requires additional special experiments.

  2. Quantitative chemical imaging with multiplex stimulated Raman scattering microscopy.

    PubMed

    Fu, Dan; Lu, Fa-Ke; Zhang, Xu; Freudiger, Christian; Pernik, Douglas R; Holtom, Gary; Xie, Xiaoliang Sunney

    2012-02-29

    Stimulated Raman scattering (SRS) microscopy is a newly developed label-free chemical imaging technique that overcomes the speed limitation of confocal Raman microscopy while avoiding the nonresonant background problem of coherent anti-Stokes Raman scattering (CARS) microscopy. Previous demonstrations have been limited to single Raman band measurements. We present a novel modulation multiplexing approach that allows real-time detection of multiple species using the fast Fourier transform. We demonstrate the quantitative determination of chemical concentrations in a ternary mixture. Furthermore, two imaging applications are pursued: (1) quantitative determination of oil content as well as pigment and protein concentration in microalgae cultures; and (2) 3D high-resolution imaging of blood, lipids, and protein distribution in ex vivo mouse skin tissue. We believe that quantitative multiplex SRS uniquely combines the advantage of fast label-free imaging with the fingerprinting capability of Raman spectroscopy and enables numerous applications in lipid biology as well as biomedical imaging. PMID:22316340

  3. Multimodality Raman and photoacoustic imaging of surface-enhanced-Raman-scattering-targeted tumor cells

    NASA Astrophysics Data System (ADS)

    Shi, Wei; Paproski, Robert J.; Shao, Peng; Forbrich, Alexander; Lewis, John D.; Zemp, Roger J.

    2016-02-01

    A multimodality Raman and photoacoustic imaging system is presented. This system has ultralow background and can detect tumor cells labeled with modified surface-enhanced-Raman-scattering (SERS) nanoparticles in vivo. Photoacoustic imaging provides microvascular context and can potentially be used to guide magnetic trapping of circulating tumor cells for SERS detection in animal models.

  4. Biological imaging with coherent Raman scattering microscopy: a tutorial

    PubMed Central

    Alfonso-García, Alba; Mittal, Richa; Lee, Eun Seong; Potma, Eric O.

    2014-01-01

    Abstract. Coherent Raman scattering (CRS) microscopy is gaining acceptance as a valuable addition to the imaging toolset of biological researchers. Optimal use of this label-free imaging technique benefits from a basic understanding of the physical principles and technical merits of the CRS microscope. This tutorial offers qualitative explanations of the principles behind CRS microscopy and provides information about the applicability of this nonlinear optical imaging approach for biological research. PMID:24615671

  5. Dental caries imaging using hyperspectral stimulated Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  6. Widefield quantitative multiplex surface enhanced Raman scattering imaging in vivo.

    PubMed

    McVeigh, Patrick Z; Mallia, Rupananda J; Veilleux, Israel; Wilson, Brian C

    2013-04-01

    In recent years numerous studies have shown the potential advantages of molecular imaging in vitro and in vivo using contrast agents based on surface enhanced Raman scattering (SERS), however the low throughput of traditional point-scanned imaging methodologies have limited their use in biological imaging. In this work we demonstrate that direct widefield Raman imaging based on a tunable filter is capable of quantitative multiplex SERS imaging in vivo, and that this imaging is possible with acquisition times which are orders of magnitude lower than achievable with comparable point-scanned methodologies. The system, designed for small animal imaging, has a linear response from (0.01 to 100 pM), acquires typical in vivo images in <10 s, and with suitable SERS reporter molecules is capable of multiplex imaging without compensation for spectral overlap. To demonstrate the utility of widefield Raman imaging in biological applications, we show quantitative imaging of four simultaneous SERS reporter molecules in vivo with resulting probe quantification that is in excellent agreement with known quantities (R²>0.98). PMID:23591913

  7. Coherent anti-Stokes Raman scattering imaging under ambient light.

    PubMed

    Zhang, Yinxin; Liao, Chien-Sheng; Hong, Weili; Huang, Kai-Chih; Yang, Huaidong; Jin, Guofan; Cheng, Ji-Xin

    2016-08-15

    We demonstrate an ambient light coherent anti-Stokes Raman scattering microscope that allows CARS imaging to be operated under environmental light for field use. The CARS signal is modulated at megahertz frequency and detected by a photodiode equipped with a lab-built resonant amplifier, then extracted through a lock-in amplifier. The filters in both the spectral domain and the frequency domain effectively blocked the room light contamination of the CARS image. In situ hyperspectral CARS imaging of tumor tissue under ambient light is demonstrated. PMID:27519113

  8. Subcellular chemical and morphological analysis by stimulated Raman scattering microscopy and image analysis techniques

    PubMed Central

    D’Arco, Annalisa; Brancati, Nadia; Ferrara, Maria Antonietta; Indolfi, Maurizio; Frucci, Maria; Sirleto, Luigi

    2016-01-01

    The visualization of heterogeneous morphology, segmentation and quantification of image features is a crucial point for nonlinear optics microscopy applications, spanning from imaging of living cells or tissues to biomedical diagnostic. In this paper, a methodology combining stimulated Raman scattering microscopy and image analysis technique is presented. The basic idea is to join the potential of vibrational contrast of stimulated Raman scattering and the strength of imaging analysis technique in order to delineate subcellular morphology with chemical specificity. Validation tests on label free imaging of polystyrene-beads and of adipocyte cells are reported and discussed. PMID:27231626

  9. Subcellular chemical and morphological analysis by stimulated Raman scattering microscopy and image analysis techniques.

    PubMed

    D'Arco, Annalisa; Brancati, Nadia; Ferrara, Maria Antonietta; Indolfi, Maurizio; Frucci, Maria; Sirleto, Luigi

    2016-05-01

    The visualization of heterogeneous morphology, segmentation and quantification of image features is a crucial point for nonlinear optics microscopy applications, spanning from imaging of living cells or tissues to biomedical diagnostic. In this paper, a methodology combining stimulated Raman scattering microscopy and image analysis technique is presented. The basic idea is to join the potential of vibrational contrast of stimulated Raman scattering and the strength of imaging analysis technique in order to delineate subcellular morphology with chemical specificity. Validation tests on label free imaging of polystyrene-beads and of adipocyte cells are reported and discussed. PMID:27231626

  10. Direct imaging of molecular symmetry by coherent anti-stokes Raman scattering.

    PubMed

    Cleff, Carsten; Gasecka, Alicja; Ferrand, Patrick; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

    2016-01-01

    Nonlinear optical methods, such as coherent anti-Stokes Raman scattering and stimulated Raman scattering, are able to perform label-free imaging, with chemical bonds specificity. Here we demonstrate that the use of circularly polarized light allows to retrieve not only the chemical nature but also the symmetry of the probed sample, in a single measurement. Our symmetry-resolved scheme offers simple access to the local organization of vibrational bonds and as a result provides enhanced image contrast for anisotropic samples, as well as an improved chemical selectivity. We quantify the local organization of vibrational bonds on crystalline and biological samples, thus providing information not accessible by spontaneous Raman and stimulated Raman scattering techniques. This work stands for a symmetry-resolved contrast in vibrational microscopy, with potential application in biological diagnostic. PMID:27189667

  11. Direct imaging of molecular symmetry by coherent anti-stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Cleff, Carsten; Gasecka, Alicja; Ferrand, Patrick; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

    2016-05-01

    Nonlinear optical methods, such as coherent anti-Stokes Raman scattering and stimulated Raman scattering, are able to perform label-free imaging, with chemical bonds specificity. Here we demonstrate that the use of circularly polarized light allows to retrieve not only the chemical nature but also the symmetry of the probed sample, in a single measurement. Our symmetry-resolved scheme offers simple access to the local organization of vibrational bonds and as a result provides enhanced image contrast for anisotropic samples, as well as an improved chemical selectivity. We quantify the local organization of vibrational bonds on crystalline and biological samples, thus providing information not accessible by spontaneous Raman and stimulated Raman scattering techniques. This work stands for a symmetry-resolved contrast in vibrational microscopy, with potential application in biological diagnostic.

  12. Direct imaging of molecular symmetry by coherent anti-stokes Raman scattering

    PubMed Central

    Cleff, Carsten; Gasecka, Alicja; Ferrand, Patrick; Rigneault, Hervé; Brasselet, Sophie; Duboisset, Julien

    2016-01-01

    Nonlinear optical methods, such as coherent anti-Stokes Raman scattering and stimulated Raman scattering, are able to perform label-free imaging, with chemical bonds specificity. Here we demonstrate that the use of circularly polarized light allows to retrieve not only the chemical nature but also the symmetry of the probed sample, in a single measurement. Our symmetry-resolved scheme offers simple access to the local organization of vibrational bonds and as a result provides enhanced image contrast for anisotropic samples, as well as an improved chemical selectivity. We quantify the local organization of vibrational bonds on crystalline and biological samples, thus providing information not accessible by spontaneous Raman and stimulated Raman scattering techniques. This work stands for a symmetry-resolved contrast in vibrational microscopy, with potential application in biological diagnostic. PMID:27189667

  13. Fast vibrational imaging of single cells and tissues by stimulated Raman scattering microscopy.

    PubMed

    Zhang, Delong; Wang, Ping; Slipchenko, Mikhail N; Cheng, Ji-Xin

    2014-08-19

    Traditionally, molecules are analyzed in a test tube. Taking biochemistry as an example, the majority of our knowledge about cellular content comes from analysis of fixed cells or tissue homogenates using tools such as immunoblotting and liquid chromatography-mass spectrometry. These tools can indicate the presence of molecules but do not provide information on their location or interaction with each other in real time, restricting our understanding of the functions of the molecule under study. For real-time imaging of labeled molecules in live cells, fluorescence microscopy is the tool of choice. Fluorescent labels, however, are too bulky for small molecules such as fatty acids, amino acids, and cholesterol. These challenges highlight a critical need for development of chemical imaging platforms that allow in situ or in vivo analysis of molecules. Vibrational spectroscopy based on spontaneous Raman scattering is widely used for label-free analysis of chemical content in cells and tissues. However, the Raman process is a weak effect, limiting its application for fast chemical imaging of a living system. With high imaging speed and 3D spatial resolution, coherent Raman scattering microscopy is enabling a new approach for real-time vibrational imaging of single cells in a living system. In most experiments, coherent Raman processes involve two excitation fields denoted as pump at ωp and Stokes at ωs. When the beating frequency between the pump and Stokes fields (ωp - ωs) is resonant with a Raman-active molecular vibration, four major coherent Raman scattering processes occur simultaneously, namely, coherent anti-Stokes Raman scattering (CARS) at (ωp - ωs) + ωp, coherent Stokes Raman scattering (CSRS) at ωs - (ωp - ωs), stimulated Raman gain (SRG) at ωs, and stimulated Raman loss (SRL) at ωp. In SRG, the Stokes beam experiences a gain in intensity, whereas in SRL, the pump beam experiences a loss. Both SRG and SRL belong to stimulated Raman scattering (SRS

  14. Fast Vibrational Imaging of Single Cells and Tissues by Stimulated Raman Scattering Microscopy

    PubMed Central

    2015-01-01

    Conspectus Traditionally, molecules are analyzed in a test tube. Taking biochemistry as an example, the majority of our knowledge about cellular content comes from analysis of fixed cells or tissue homogenates using tools such as immunoblotting and liquid chromatography–mass spectrometry. These tools can indicate the presence of molecules but do not provide information on their location or interaction with each other in real time, restricting our understanding of the functions of the molecule under study. For real-time imaging of labeled molecules in live cells, fluorescence microscopy is the tool of choice. Fluorescent labels, however, are too bulky for small molecules such as fatty acids, amino acids, and cholesterol. These challenges highlight a critical need for development of chemical imaging platforms that allow in situ or in vivo analysis of molecules. Vibrational spectroscopy based on spontaneous Raman scattering is widely used for label-free analysis of chemical content in cells and tissues. However, the Raman process is a weak effect, limiting its application for fast chemical imaging of a living system. With high imaging speed and 3D spatial resolution, coherent Raman scattering microscopy is enabling a new approach for real-time vibrational imaging of single cells in a living system. In most experiments, coherent Raman processes involve two excitation fields denoted as pump at ωp and Stokes at ωs. When the beating frequency between the pump and Stokes fields (ωp – ωs) is resonant with a Raman-active molecular vibration, four major coherent Raman scattering processes occur simultaneously, namely, coherent anti-Stokes Raman scattering (CARS) at (ωp – ωs) + ωp, coherent Stokes Raman scattering (CSRS) at ωs – (ωp – ωs), stimulated Raman gain (SRG) at ωs, and stimulated Raman loss (SRL) at ωp. In SRG, the Stokes beam experiences a gain in intensity, whereas in SRL, the pump beam experiences a loss. Both SRG and SRL belong to

  15. Spectrometer-free vibrational imaging by retrieving stimulated Raman signal from highly scattered photons

    PubMed Central

    Liao, Chien-Sheng; Wang, Pu; Wang, Ping; Li, Junjie; Lee, Hyeon Jeong; Eakins, Gregory; Cheng, Ji-Xin

    2015-01-01

    In vivo vibrational spectroscopic imaging is inhibited by relatively slow spectral acquisition on the second scale and low photon collection efficiency for a highly scattering system. Recently developed multiplex coherent anti-Stokes Raman scattering and stimulated Raman scattering techniques have improved the spectral acquisition time down to microsecond scale. These methods using a spectrometer setting are not suitable for turbid systems in which nearly all photons are scattered. We demonstrate vibrational imaging by spatial frequency multiplexing of incident photons and single photodiode detection of a stimulated Raman spectrum within 60 μs. Compared to the spectrometer setting, our method improved the photon collection efficiency by two orders of magnitude for highly scattering specimens. We demonstrated in vivo imaging of vitamin E distribution on mouse skin and in situ imaging of human breast cancerous tissues. The reported work opens new opportunities for spectroscopic imaging in a surgical room and for development of deep-tissue Raman spectroscopy toward molecular level diagnosis. PMID:26601311

  16. Imaging of director fields in liquid crystals using stimulated Raman scattering microscopy.

    PubMed

    Lee, Taewoo; Mundoor, Haridas; Gann, Derek G; Callahan, Timothy J; Smalyukh, Ivan I

    2013-05-20

    We demonstrate an approach for background-free three-dimensional imaging of director fields in liquid crystals using stimulated Raman scattering microscopy. This imaging technique is implemented using a single femtosecond pulsed laser and a photonic crystal fiber, providing Stokes and pump frequencies needed to access Raman shifts of different chemical bonds of molecules and allowing for chemically selective and broadband imaging of both pristine liquid crystals and composite materials. Using examples of model three-dimensional structures of director fields, we show that the described technique is a powerful tool for mapping of long-range molecular orientation patterns in soft matter via polarized chemical-selective imaging. PMID:23736433

  17. Standoff explosives trace detection and imaging by selective stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Bremer, Marshall T.; Dantus, Marcos

    2013-08-01

    We introduce a sensitive method for laser based standoff detection of chemicals based on stimulated Raman scattering. Selective excitation of a particular Raman transition is detected by measuring the diffusely reflected laser light from a distant surface. The method simultaneously measures stimulated Raman loss and gain within a single laser shot and is insensitive to the optical properties (reflectivity/absorptivity) of the substrate. We demonstrate the specificity and sensitivity by detecting and imaging nanogram analyte micro-crystals on paper, fabric, and plastic substrates at 1 to 10 m standoff distance using only 10 mW of laser power from a single femtosecond laser.

  18. Label-Free Cellular Imaging by Broadband Coherent Anti-Stokes Raman Scattering Microscopy

    PubMed Central

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

    2010-01-01

    Raman microspectroscopy can provide the chemical contrast needed to characterize the complex intracellular environment and macromolecular organization in cells without exogenous labels. It has shown a remarkable ability to detect chemical changes underlying cell differentiation and pathology-related chemical changes in tissues but has not been widely adopted for imaging, largely due to low signal levels. Broadband coherent anti-Stokes Raman scattering (B-CARS) offers the same inherent chemical contrast as spontaneous Raman but with increased acquisition rates. To date, however, only spectrally resolved signals from the strong CH-related vibrations have been used for CARS imaging. Here, we obtain Raman spectral images of single cells with a spectral range of 600–3200 cm−1, including signatures from weakly scattering modes as well as CH vibrations. We also show that B-CARS imaging can be used to measure spectral signatures of individual cells at least fivefold faster than spontaneous Raman microspectroscopy and can be used to generate maps of biochemical species in cells. This improved spectral range and signal intensity opens the door for more widespread use of vibrational spectroscopic imaging in biology and clinical diagnostics. PMID:20959111

  19. Coherent anti-Stokes Raman scattering hyperspectral tissue imaging with a wavelength-swept system.

    PubMed

    Bégin, Steve; Burgoyne, Bryan; Mercier, Vincent; Villeneuve, Alain; Vallée, Réal; Côté, Daniel

    2011-01-01

    We present a wavelength-swept coherent anti-Stokes Raman scattering (WS-CARS) spectroscopy system for hyperspectral imaging in thick tissue. We use a strategy where the Raman lines are excited sequentially, circumventing the need for a spectrometer. This fibre laser system, consisting of a pump laser synchronized with a rapidly tunable programmable laser (PL), can access Raman lines over a significant fraction of the high wavenumber region (2700-2950 cm(-1)) at rates of up to 10,000 spectral points per second. To demonstrate its capabilities, we have acquired WS-CARS spectra of several samples as well as images and hyperspectral images (HSI) of thick tissue both in forward and epi-detection. This instrument should be especially useful in providing local biochemical information with surrounding context supplied by imaging. PMID:21559141

  20. Coherent anti-Stokes Raman scattering hyperspectral tissue imaging with a wavelength-swept system

    PubMed Central

    Bégin, Steve; Burgoyne, Bryan; Mercier, Vincent; Villeneuve, Alain; Vallée, Réal; Côté, Daniel

    2011-01-01

    We present a wavelength-swept coherent anti-Stokes Raman scattering (WS-CARS) spectroscopy system for hyperspectral imaging in thick tissue. We use a strategy where the Raman lines are excited sequentially, circumventing the need for a spectrometer. This fibre laser system, consisting of a pump laser synchronized with a rapidly tunable programmable laser (PL), can access Raman lines over a significant fraction of the high wavenumber region (2700–2950 cm−1) at rates of up to 10,000 spectral points per second. To demonstrate its capabilities, we have acquired WS-CARS spectra of several samples as well as images and hyperspectral images (HSI) of thick tissue both in forward and epi-detection. This instrument should be especially useful in providing local biochemical information with surrounding context supplied by imaging. PMID:21559141

  1. Raman spectroscopy and coherent anti-Stokes Raman scattering imaging: prospective tools for monitoring skeletal cells and skeletal regeneration

    PubMed Central

    Moura, Catarina Costa; Tare, Rahul S.; Oreffo, Richard O. C.; Mahajan, Sumeet

    2016-01-01

    The use of skeletal stem cells (SSCs) for cell-based therapies is currently one of the most promising areas for skeletal disease treatment and skeletal tissue repair. The ability for controlled modification of SSCs could provide significant therapeutic potential in regenerative medicine, with the prospect to permanently repopulate a host with stem cells and their progeny. Currently, SSC differentiation into the stromal lineages of bone, fat and cartilage is assessed using different approaches that typically require cell fixation or lysis, which are invasive or even destructive. Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy present an exciting alternative for studying biological systems in their natural state, without any perturbation. Here we review the applications of Raman spectroscopy and CARS imaging in stem-cell research, and discuss the potential of these two techniques for evaluating SSCs, skeletal tissues and skeletal regeneration as an exemplar. PMID:27170652

  2. Raman spectroscopy and coherent anti-Stokes Raman scattering imaging: prospective tools for monitoring skeletal cells and skeletal regeneration.

    PubMed

    Moura, Catarina Costa; Tare, Rahul S; Oreffo, Richard O C; Mahajan, Sumeet

    2016-05-01

    The use of skeletal stem cells (SSCs) for cell-based therapies is currently one of the most promising areas for skeletal disease treatment and skeletal tissue repair. The ability for controlled modification of SSCs could provide significant therapeutic potential in regenerative medicine, with the prospect to permanently repopulate a host with stem cells and their progeny. Currently, SSC differentiation into the stromal lineages of bone, fat and cartilage is assessed using different approaches that typically require cell fixation or lysis, which are invasive or even destructive. Raman spectroscopy and coherent anti-Stokes Raman scattering (CARS) microscopy present an exciting alternative for studying biological systems in their natural state, without any perturbation. Here we review the applications of Raman spectroscopy and CARS imaging in stem-cell research, and discuss the potential of these two techniques for evaluating SSCs, skeletal tissues and skeletal regeneration as an exemplar. PMID:27170652

  3. Picosecond spectral coherent anti-Stokes Raman scattering imaging with principal component analysis of meibomian glands

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Yu; Suhalim, Jeffrey L.; Nien, Chyong Ly; Miljković, Miloš D.; Diem, Max; Jester, James V.; Potma, Eric. O.

    2011-02-01

    The lipid distribution in the mouse meibomian gland was examined with picosecond spectral anti-Stokes Raman scattering (CARS) imaging. Spectral CARS data sets were generated by imaging specific localized regions of the gland within tissue sections at consecutive Raman shifts in the CH2 stretching vibrational range. Spectral differences between the location specific CARS spectra obtained in the lipid-rich regions of the acinus and the central duct were observed, which were confirmed with a Raman microspectroscopic analysis, and attributed to meibum lipid modifications within the gland. A principal component analysis of the spectral data set reveals changes in the CARS spectrum when transitioning from the acini to the central duct. These results demonstrate the utility of picosecond spectral CARS imaging combined with multivariate analysis for assessing differences in the distribution and composition of lipids in tissues.

  4. Label-Free Nanometer-Resolution Imaging of Biological Architectures through Surface Enhanced Raman Scattering

    PubMed Central

    Ayas, Sencer; Cinar, Goksu; Ozkan, Alper Devrim; Soran, Zeliha; Ekiz, Oner; Kocaay, Deniz; Tomak, Aysel; Toren, Pelin; Kaya, Yasin; Tunc, Ilknur; Zareie, Hadi; Tekinay, Turgay; Tekinay, Ayse Begum; Guler, Mustafa Ozgur; Dana, Aykutlu

    2013-01-01

    Label free imaging of the chemical environment of biological specimens would readily bridge the supramolecular and the cellular scales, if a chemical fingerprint technique such as Raman scattering can be coupled with super resolution imaging. We demonstrate the possibility of label-free super-resolution Raman imaging, by applying stochastic reconstruction to temporal fluctuations of the surface enhanced Raman scattering (SERS) signal which originate from biomolecular layers on large-area plasmonic surfaces with a high and uniform hot-spot density (>1011/cm2, 20 to 35 nm spacing). A resolution of 20 nm is demonstrated in reconstructed images of self-assembled peptide network and fibrilated lamellipodia of cardiomyocytes. Blink rate density is observed to be proportional to the excitation intensity and at high excitation densities (>10 kW/cm2) blinking is accompanied by molecular breakdown. However, at low powers, simultaneous Raman measurements show that SERS can provide sufficient blink rates required for image reconstruction without completely damaging the chemical structure. PMID:24022059

  5. Hyperspectral microscopic imaging by multiplex coherent anti-Stokes Raman scattering (CARS)

    NASA Astrophysics Data System (ADS)

    Khmaladze, Alexander; Jasensky, Joshua; Zhang, Chi; Han, Xiaofeng; Ding, Jun; Seeley, Emily; Liu, Xinran; Smith, Gary D.; Chen, Zhan

    2011-10-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is a powerful technique to image the chemical composition of complex samples in biophysics, biology and materials science. CARS is a four-wave mixing process. The application of a spectrally narrow pump beam and a spectrally wide Stokes beam excites multiple Raman transitions, which are probed by a probe beam. This generates a coherent directional CARS signal with several orders of magnitude higher intensity relative to spontaneous Raman scattering. Recent advances in the development of ultrafast lasers, as well as photonic crystal fibers (PCF), enable multiplex CARS. In this study, we employed two scanning imaging methods. In one, the detection is performed by a photo-multiplier tube (PMT) attached to the spectrometer. The acquisition of a series of images, while tuning the wavelengths between images, allows for subsequent reconstruction of spectra at each image point. The second method detects CARS spectrum in each point by a cooled coupled charged detector (CCD) camera. Coupled with point-by-point scanning, it allows for a hyperspectral microscopic imaging. We applied this CARS imaging system to study biological samples such as oocytes.

  6. Label-free DNA imaging in vivo with stimulated Raman scattering microscopy

    PubMed Central

    Lu, Fa-Ke; Basu, Srinjan; Igras, Vivien; Hoang, Mai P.; Ji, Minbiao; Fu, Dan; Holtom, Gary R.; Neel, Victor A.; Freudiger, Christian W.; Fisher, David E.; Xie, X. Sunney

    2015-01-01

    Label-free DNA imaging is highly desirable in biology and medicine to perform live imaging without affecting cell function and to obtain instant histological tissue examination during surgical procedures. Here we show a label-free DNA imaging method with stimulated Raman scattering (SRS) microscopy for visualization of the cell nuclei in live animals and intact fresh human tissues with subcellular resolution. Relying on the distinct Raman spectral features of the carbon-hydrogen bonds in DNA, the distribution of DNA is retrieved from the strong background of proteins and lipids by linear decomposition of SRS images at three optimally selected Raman shifts. Based on changes on DNA condensation in the nucleus, we were able to capture chromosome dynamics during cell division both in vitro and in vivo. We tracked mouse skin cell proliferation, induced by drug treatment, through in vivo counting of the mitotic rate. Furthermore, we demonstrated a label-free histology method for human skin cancer diagnosis that provides comparable results to other conventional tissue staining methods such as H&E. Our approach exhibits higher sensitivity than SRS imaging of DNA in the fingerprint spectral region. Compared with spontaneous Raman imaging of DNA, our approach is three orders of magnitude faster, allowing both chromatin dynamic studies and label-free optical histology in real time. PMID:26324899

  7. Label-free DNA imaging in vivo with stimulated Raman scattering microscopy.

    PubMed

    Lu, Fa-Ke; Basu, Srinjan; Igras, Vivien; Hoang, Mai P; Ji, Minbiao; Fu, Dan; Holtom, Gary R; Neel, Victor A; Freudiger, Christian W; Fisher, David E; Xie, X Sunney

    2015-09-15

    Label-free DNA imaging is highly desirable in biology and medicine to perform live imaging without affecting cell function and to obtain instant histological tissue examination during surgical procedures. Here we show a label-free DNA imaging method with stimulated Raman scattering (SRS) microscopy for visualization of the cell nuclei in live animals and intact fresh human tissues with subcellular resolution. Relying on the distinct Raman spectral features of the carbon-hydrogen bonds in DNA, the distribution of DNA is retrieved from the strong background of proteins and lipids by linear decomposition of SRS images at three optimally selected Raman shifts. Based on changes on DNA condensation in the nucleus, we were able to capture chromosome dynamics during cell division both in vitro and in vivo. We tracked mouse skin cell proliferation, induced by drug treatment, through in vivo counting of the mitotic rate. Furthermore, we demonstrated a label-free histology method for human skin cancer diagnosis that provides comparable results to other conventional tissue staining methods such as H&E. Our approach exhibits higher sensitivity than SRS imaging of DNA in the fingerprint spectral region. Compared with spontaneous Raman imaging of DNA, our approach is three orders of magnitude faster, allowing both chromatin dynamic studies and label-free optical histology in real time. PMID:26324899

  8. Holographic coherent anti-Stokes Raman scattering bio-imaging

    PubMed Central

    Shi, Kebin; Edwards, Perry S.; Hu, Jing; Xu, Qian; Wang, Yanming; Psaltis, Demetri; Liu, Zhiwen

    2012-01-01

    CARS holography captures both the amplitude and the phase of a complex anti-Stokes field, and can perform three-dimensional imaging by digitally focusing onto different depths inside a specimen. The application of CARS holography for bio-imaging is demonstrated. It is shown that holographic CARS imaging of sub-cellular components in live HeLa cells can be achieved. PMID:22808443

  9. Effects of tissue fixation on coherent anti-Stokes Raman scattering images of brain

    NASA Astrophysics Data System (ADS)

    Galli, Roberta; Uckermann, Ortrud; Koch, Edmund; Schackert, Gabriele; Kirsch, Matthias; Steiner, Gerald

    2014-07-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is an emerging multiphoton technique for the label-free histopathology of the central nervous system, by imaging the lipid content within the tissue. In order to apply the technique on standard histology sections, it is important to know the effects of tissue fixation on the CARS image. Here, we report the effects of two common fixation methods, namely with formalin and methanol-acetone, on mouse brain and human glioblastoma tissue. The variations induced by fixation on the CARS contrast and intensity were compared and interpreted using Raman microspectroscopy. The results show that, whenever unfixed cryosections cannot be used, fixation with formalin constitutes an alternative which does not deteriorate substantially the contrast generated by the different brain structures in the CARS image. Fixation with methanol-acetone strongly modifies the tissue lipid content and is therefore incompatible with the CARS imaging.

  10. Chemical imaging and microspectroscopy with spectral focusing coherent anti-Stokes Raman scattering.

    PubMed

    Chen, Bi-Chang; Sung, Jiha; Wu, Xiaoxi; Lim, Sang-Hyun

    2011-02-01

    We demonstrate two different coherent anti-Stokes Raman scattering (CARS) microscopy and microspectroscopy methods based on the spectral focusing mechanism. The first method uses strongly chirped broadband pulses from a single Ti:sapphire laser and generates CARS signals at the fingerprint region. Fast modulation of the time delay between the pump and Stokes laser pulses coupled with lock-in signal detection significantly reduces the nonresonant background and produces Raman-like CARS signals with a spectral resolution of 20 cm(-1). The second method generates CARS signals in the CH (carbon-hydrogen) stretching region with IR supercontinuum pulses from a photonic crystal fiber. The spectral resolution of 30 cm(-1) is achieved. Maximum entropy method is used to retrieve a Raman-equivalent CARS spectrum from lipid membranes. Chemical imaging and microspectroscopy are demonstrated with various samples. PMID:21361675

  11. Video-rate molecular imaging in vivo with stimulated Raman scattering.

    PubMed

    Saar, Brian G; Freudiger, Christian W; Reichman, Jay; Stanley, C Michael; Holtom, Gary R; Xie, X Sunney

    2010-12-01

    Optical imaging in vivo with molecular specificity is important in biomedicine because of its high spatial resolution and sensitivity compared with magnetic resonance imaging. Stimulated Raman scattering (SRS) microscopy allows highly sensitive optical imaging based on vibrational spectroscopy without adding toxic or perturbative labels. However, SRS imaging in living animals and humans has not been feasible because light cannot be collected through thick tissues, and motion-blur arises from slow imaging based on backscattered light. In this work, we enable in vivo SRS imaging by substantially enhancing the collection of the backscattered signal and increasing the imaging speed by three orders of magnitude to video rate. This approach allows label-free in vivo imaging of water, lipid, and protein in skin and mapping of penetration pathways of topically applied drugs in mice and humans. PMID:21127249

  12. Lock-in-detection-free line-scan stimulated Raman scattering microscopy for near video-rate Raman imaging.

    PubMed

    Wang, Zi; Zheng, Wei; Huang, Zhiwei

    2016-09-01

    We report on the development of a unique lock-in-detection-free line-scan stimulated Raman scattering microscopy technique based on a linear detector with a large full well capacity controlled by a field-programmable gate array (FPGA) for near video-rate Raman imaging. With the use of parallel excitation and detection scheme, the line-scan SRS imaging at 20 frames per second can be acquired with a ∼5-fold lower excitation power density, compared to conventional point-scan SRS imaging. The rapid data communication between the FPGA and the linear detector allows a high line-scanning rate to boost the SRS imaging speed without the need for lock-in detection. We demonstrate this lock-in-detection-free line-scan SRS imaging technique using the 0.5 μm polystyrene and 1.0 μm poly(methyl methacrylate) beads mixed in water, as well as living gastric cancer cells. PMID:27607947

  13. Sparse sampling for fast hyperspectral coherent anti-Stokes Raman scattering imaging.

    PubMed

    Masia, Francesco; Borri, Paola; Langbein, Wolfgang

    2014-02-24

    We demonstrate a method to increase the acquisition speed in coherent anti-Stokes Raman scattering (CARS) hyperspectral imaging while retaining the relevant spectral information. The method first determines the important spectral components of a sample from a hyper-spectral image over a small number of spatial points but a large number of spectral points covering the accessible spectral range and sampling the instrument spectral resolution at the Nyquist limit. From these components we determine a small set of frequencies needed to retrieve the weights of the components with minimum error for a given measurement noise. Hyperspectral images with a large number of spatial points, for example covering a large spatial region, are then measured at this small set of frequencies, and a reconstruction algorithm is applied to generate the full spectral range and resolution. The resulting spectra are suited to retrieve from the CARS intensity the CARS susceptibility which is linear in the concentration, and apply unsupervised quantitative analysis methods such as FSC3. We demonstrate the method on CARS hyperspectral images of human osteosarcoma U2OS cell, with a reduction in the acquisition time by a factor of 25. This method is suited also for other coherent vibrational microscopy techniques such as stimulated Raman scattering, and in general for hyperspectral imaging techniques with sequential spectral acquisition. PMID:24663723

  14. Coherent Raman scattering microscopy for label-free imaging of live amphioxus

    NASA Astrophysics Data System (ADS)

    Yu, Zhilong; Chen, Tao; Zhang, Xiannian; Shen, Jie; Chen, Junyuan; Huang, Yanyi

    2012-03-01

    The existence of notochord distinguishes chordates from other phyla. Amphioxus is the only animal that keeps notochord during the whole life. Notochord is a unique organ for amphioxus, with its vertically arranged muscular notochordal plates, which is different from notochords in embryos of other chordates. We use stimulated Raman scattering (SRS) microscopy as a non-invasive technique to image the chemical components in amphioxus notochord. SRS provides chemical specificity as spontaneous Raman does and offers a higher sensitivity for fast acquisition. Unlike coherent anti- Stokes Raman scattering (CARS) microscopy, SRS microscopy doesn't have non-resonant background and can better differentiate different components in the specimen. We verify that the notochord is a protein-rich organ, which agrees well with the result of conventional staining methods. Detailed structures in notochordal plates and notochordal sheath are revealed by SRS microscopy with diffraction limited resolution. Our experiment shows that SRS microscopy is an excellent imaging tool for biochemical research with its intrinsic chemical selectivity, high spatiotemporal resolution and native 3D optical sectioning ability.

  15. Raman Imaging

    NASA Astrophysics Data System (ADS)

    Stewart, Shona; Priore, Ryan J.; Nelson, Matthew P.; Treado, Patrick J.

    2012-07-01

    The past decade has seen an enormous increase in the number and breadth of imaging techniques developed for analysis in many industries, including pharmaceuticals, food, and especially biomedicine. Rather than accept single-dimensional forms of information, users now demand multidimensional assessment of samples. High specificity and the need for little or no sample preparation make Raman imaging a highly attractive analytical technique and provide motivation for continuing advances in its supporting technology and utilization. This review discusses the current tools employed in Raman imaging, the recent advances, and the major applications in this ever-growing analytical field.

  16. Label-free imaging of adipogenesis by coherent anti-stokes Raman scattering microscopy.

    PubMed

    Isomäki, Antti; Sillat, Tarvo; Ainola, Mari; Liljeström, Mikko; Konttinen, Yrjö T; Hukkanen, Mika

    2014-01-01

    Label-free imaging technologies to monitor the events associated with early, intermediate and late adipogenic differentiation in multipotent mesenchymal stromal cells (MSCs) offer an attractive and convenient alternative to conventional fixative based lipid dyes such as Oil Red O and Sudan Red, fluorescent labels such as LipidTOX, and more indirect methods such as qRT-PCR analyses of specific adipocyte differentiation markers such as peroxisome PPARγ and LPL. Coherent anti-Stokes Raman scattering (CARS) microscopy of live cells is a sensitive and fast imaging method enabling evaluation of the adipogenic differentiation with chemical specificity. CARS microscopy is based on imaging structures of interest by displaying the characteristic intrinsic vibrational contrast of chemical bonds. The method is nontoxic, non-destructive, and minimally invasive, thus presenting a promising method for longitudinal analyses of live cells and tissues. CARS provides a coherently emitted signal that is much stronger than the spontaneous Raman scattering. The anti-Stokes signal is blue shifted from the incident wavelength, thus reducing the non-vibrational background present in most biological materials. In this chapter, we aim to provide a detailed approach on how to induce adipogenic differentiation in MSC cultures, and present our methods related to label-free CARS imaging of the events associated with the adipogenesis. PMID:24706284

  17. Raman microspectrometer combined with scattering microscopy and lensless imaging for bacteria identification

    NASA Astrophysics Data System (ADS)

    Strola, S. A.; Schultz, E.; Allier, C. P.; DesRoches, B.; Lemmonier, J.; Dinten, J.-M.

    2013-03-01

    In this paper, we report on a compact prototype capable both of lensfree imaging, Raman spectrometry and scattering microscopy from bacteria samples. This instrument allows high-throughput real-time characterization without the need of markers, making it potentially suitable to field label-free biomedical and environmental applications. Samples are illuminated from above with a focused-collimated 532nm laser beam and can be x-y-z scanned. The bacteria detection is based on emerging lensfree imaging technology able to localize cells of interest over a large field-of-view of 24mm2. Raman signal and scattered light are then collected by separate measurement arms simultaneously. In the first arm the emission light is fed by a fiber into a prototype spectrometer, developed by Tornado Spectral System based on Tornado's High Throughput Virtual Slit (HTVS) novel technology. The enhanced light throughput in the spectral region of interest (500-1800 cm-1) reduces Raman acquisition time down to few seconds, thus facilitating experimental protocols and avoiding the bacteria deterioration induced by laser thermal heating. Scattered light impinging in the second arm is collected onto a charge-coupled-device. The reconstructed image allows studying the single bacteria diffraction pattern and their specific structural features. The characterization and identification of different bacteria have been performed to validate and optimize the acquisition system and the component setup. The results obtained demonstrate the benefits of these three techniques combination by providing the precise bacteria localization, their chemical composition and a morphology description. The procedure for a rapid identification of particular pathogen bacteria in a sample is illustrated.

  18. Raman scattering enhanced by plasmonic clusters and its application to single-molecule imaging

    SciTech Connect

    Yasuike, Tomokazu; Nobusada, Katsuyuki

    2015-12-31

    The optical response of the linear Au{sub 8} cluster is investigated by the linear response theory based on the density functional theory. It is revealed that the observed many peaks in the visible region originate from the interaction of the ideal plasmonic excitation along the molecular axis with the background d-electron excitations, i.e., the Landau damping. In spite of the existence of the damping, the Raman scattering is shown to be enhanced remarkably by the incident light resonant to the visible excitations. The novel imaging experiment with the atomic resolution is proposed by utilizing a plasmonic cluster as the probing tip.

  19. Microsecond Scale Vibrational Spectroscopic Imaging by Multiplex Stimulated Raman Scattering Microscopy

    PubMed Central

    Liao, Chien-Sheng; Slipchenko, Mikhail N.; Wang, Ping; Li, Junjie; Lee, Seung-Young; Oglesbee, Robert A.; Cheng, Ji-Xin

    2015-01-01

    Real-time vibrational spectroscopic imaging is desired for monitoring cellular states and cellular processes in a label-free manner. Raman spectroscopic imaging of highly dynamic systems is inhibited by relatively slow spectral acquisition on millisecond to second scale. Here, we report microsecond scale vibrational spectroscopic imaging by lock-in free parallel detection of spectrally dispersed stimulated Raman scattering signal. Using a homebuilt tuned amplifier array, our method enables Raman spectral acquisition, within the window defined by the broadband pulse, at the speed of 32 microseconds and with close to shot-noise limited detection sensitivity. Incorporated with multivariate curve resolution analysis, our platform allows compositional mapping of lipid droplets in single live cells, observation of intracellular retinoid metabolism, discrimination of fat droplets from protein-rich organelles in Caenorhabditis elegans, spectral detection of fast flowing tumor cells, and monitoring drug diffusion through skin tissue in vivo. The reported technique opens new opportunities for compositional analysis of cellular compartment in a microscope setting and high-throughput spectral profiling of single cells in a flow cytometer setting. PMID:26167336

  20. Raman scattering in crystals

    SciTech Connect

    Edwards, D.F.

    1988-09-30

    A tutorial presentation is given of Raman scattering in crystals. The physical concepts are emphasized rather than the detailed mathematical formalism. Starting with an introduction to the concepts of phonons and conservation laws, the effects of photon-phonon interactions are presented. This interaction concept is shown for a simple cubic crystal and is extended to a uniaxial crystal. The correlation table method is used for determining the number and symmetry of the Raman active modes. Finally, examples are given to illustrate the relative ease of using this group theoretical method and the predictions are compared with measured Raman spectra. 37 refs., 17 figs., 6 tabs.

  1. Live-Cell Bioorthogonal Chemical Imaging: Stimulated Raman Scattering Microscopy of Vibrational Probes.

    PubMed

    Wei, Lu; Hu, Fanghao; Chen, Zhixing; Shen, Yihui; Zhang, Luyuan; Min, Wei

    2016-08-16

    Innovations in light microscopy have tremendously revolutionized the way researchers study biological systems with subcellular resolution. In particular, fluorescence microscopy with the expanding choices of fluorescent probes has provided a comprehensive toolkit to tag and visualize various molecules of interest with exquisite specificity and high sensitivity. Although fluorescence microscopy is currently the method of choice for cellular imaging, it faces fundamental limitations for studying the vast number of small biomolecules. This is because common fluorescent labels, which are relatively bulky, could introduce considerable perturbation to or even completely alter the native functions of vital small biomolecules. Hence, despite their immense functional importance, these small biomolecules remain largely undetectable by fluorescence microscopy. To address this challenge, a bioorthogonal chemical imaging platform has recently been introduced. By coupling stimulated Raman scattering (SRS) microscopy, an emerging nonlinear Raman microscopy technique, with tiny and Raman-active vibrational probes (e.g., alkynes and stable isotopes), bioorthogonal chemical imaging exhibits superb sensitivity, specificity, and biocompatibility for imaging small biomolecules in live systems. In this Account, we review recent technical achievements for visualizing a broad spectrum of small biomolecules, including ribonucleosides and deoxyribonucleosides, amino acids, fatty acids, choline, glucose, cholesterol, and small-molecule drugs in live biological systems ranging from individual cells to animal tissues and model organisms. Importantly, this platform is compatible with live-cell biology, thus allowing real-time imaging of small-molecule dynamics. Moreover, we discuss further chemical and spectroscopic strategies for multicolor bioorthogonal chemical imaging, a valuable technique in the era of "omics". As a unique tool for biological discovery, this platform has been applied to

  2. Simultaneous stimulated Raman scattering and higher harmonic generation imaging for liver disease diagnosis without labeling

    NASA Astrophysics Data System (ADS)

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

    2014-02-01

    Nonlinear optical microscopy (e.g., higher harmonic (second-/third- harmonic) generation (HHG), simulated Raman scattering (SRS)) has high diagnostic sensitivity and chemical specificity, making it a promising tool for label-free tissue and cell imaging. In this work, we report a development of a simultaneous SRS and HHG imaging technique for characterization of liver disease in a bile-duct-ligation rat-modal. HHG visualizes collagens formation and reveals the cell morphologic changes associated with liver fibrosis; whereas SRS identifies the distributions of hepatic fat cells formed in steatosis liver tissue. This work shows that the co-registration of SRS and HHG images can be an effective means for label-free diagnosis and characterization of liver steatosis/fibrosis at the cellular and molecular levels.

  3. Stimulated Raman scattering detection for chemically specific time-resolved imaging of gases.

    PubMed

    Amer, Eynas; Gren, Per; Edenharder, Stefan; Sjödahl, Mikael

    2016-05-01

    A stimulated Raman scattering (SRS) imaging technique based on spatial modulation of the pump beam has been used to study gases. The SRS gain signal was separated from the Stokes beam background in the spatial frequency domain. The SRS signal shows linear behaviour with the gas pressure at a range from 1.0 to 8.0 bars. The signal is linearly proportional to the pump beam intensity while it is enhanced with increasing the Stokes beam intensity to a certain limit than it saturates. Further, the chemical specificity of the technique has been investigated. Two sharp peaks with line width at half maximum of about 0.30 nm have been obtained at Stokes beam wavelengths of 629.93 nm and 634.05 nm corresponding to the methane and ethylene gases, respectively. The results show that SRS imaging is a promising technique to provide chemical specificity as well as spatial and temporal information of gaseous species. PMID:27137608

  4. Simultaneous Raman scattering and laser-induced fluorescence for multispecies imaging in turbulent flames.

    PubMed

    Schefer, R W; Namazian, M; Kelly, J

    1991-06-01

    A multispecies imaging technique for single-shot, simultaneous measurement of the OH, CH, and CH(4) concentrations in turbulent nonpremixed flames is described. A unique aspect of the system is the use of a two-wavelength multipass cell to form both a visible and a UV laser sheet. The UV beam is used to excite fluorescence in the OH molecule, while Raman scattering from CH(4) molecules and fluorescence induced in CH is achieved by using the visible beam. The visible and UV lasers are operated simultaneously, and the resulting signals are recorded by two vidicon cameras. The sheet intensity provided by the multipass cell is sufficient to saturate the OH transition, which makes single-shot, laser-saturated fluorescence imaging measurements possible. PMID:19776809

  5. Simultaneous Raman scattering and laser-induced fluorescence for multispecies imaging in turbulent flames

    SciTech Connect

    Schefer, R.W.; Namazian, M.; Kelly, J. )

    1991-06-01

    A multispecies imaging technique for single-shot, simultaneous measurement of the OH, CH, and CH{sub 4} concentrations in turbulent nonpremixed flames is described. A unique aspect of the system is the use of a two-wavelength multipass cell to form both a visible and a UV laser sheet. The UV beam is used to excite fluorescence in the OH molecule, while Raman scattering from CH{sub 4} molecules and fluorescence induced in CH is achieved by using the visible beam. The visible and UV lasers are operated simultaneously, and the resulting signals are recorded by two vidicon cameras. The sheet intensity provided by the multipass cell is sufficient to saturate the OH transition, which makes single-shot, laser-saturated fluorescence imaging measurements possible.

  6. A CMOS image sensor using high-speed lock-in pixels for stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Lioe, DeXing; Mars, Kamel; Takasawa, Taishi; Yasutomi, Keita; Kagawa, Keiichiro; Hashimoto, Mamoru; Kawahito, Shoji

    2016-03-01

    A CMOS image sensor using high-speed lock-in pixels for stimulated Raman scattering (SRS) spectroscopy is presented in this paper. The effective SRS signal from the stimulated emission of SRS mechanism is very small in contrast to the offset of a probing laser source, which is in the ratio of 10-4 to 10-5. In order to extract this signal, the common offset component is removed, and the small difference component is sampled using switched-capacitor integrator with a fully differential amplifier. The sampling is performed over many integration cycles to achieve appropriate amplification. The lock-in pixels utilizes high-speed lateral electric field charge modulator (LEFM) to demodulate the SRS signal which is modulated at high-frequency of 20MHz. A prototype chip is implemented using 0.11μm CMOS image sensor technology.

  7. Imaging the Intact Mouse Cornea Using Coherent Anti-Stokes Raman scattering (CARS)

    PubMed Central

    Ammar, David A.; Lei, Tim C.; Kahook, Malik Y.; Masihzadeh, Omid

    2013-01-01

    Purpose. The aim of this study was to image the cellular and noncellular structures of the cornea and limbus in an intact mouse eye using the vibrational oscillation of the carbon–hydrogen bond in lipid membranes and autofluorescence as label-free contrast agents. Methods. Freshly enucleated mouse eyes were imaged using two nonlinear optical techniques: coherent anti-Stokes Raman scattering (CARS) and two-photon autofluorescence (TPAF). Sequential images were collected through the full thickness of the cornea and limbal regions. Line scans along the transverse/sagittal axes were also performed. Results. Analysis of multiple CARS/TPAF images revealed that corneal epithelial and endothelial cells could be identified by the lipid-rich plasma membrane CARS signal. The fluorescent signal from the collagen fibers of the corneal stroma was evident in the TPAF channel. The transition from the cornea to sclera at the limbus was marked by a change in collagen pattern (TPAF channel) and thickness of surface cells (CARS channel). Regions within the corneal stroma that lack collagen autofluorescence coincided with CARS signal, indicating the presence of stromal fibroblasts or nerve fibers. Conclusions. The CARS technique was successful in imaging cells in the intact mouse eye, both at the surface and within corneal tissue. Multiphoton images were comparable to histologic sections. The methods described here represent a new avenue for molecular specific imaging of the mouse eye. The lack of need for tissue fixation is unique compared with traditional histology imaging techniques. PMID:23821187

  8. Coherent anti-Stokes Raman scattering hyperspectral imaging of cartilage aiming for state discrimination of cell

    NASA Astrophysics Data System (ADS)

    Shiozawa, Manabu; Shirai, Masataka; Izumisawa, Junko; Tanabe, Maiko; Watanabe, Koich

    2016-07-01

    Noninvasive cell analyses are increasingly important in the medical field. A coherent anti-Stokes Raman scattering (CARS) microscope is the noninvasive imaging equipment and enables to obtain images indicating molecular distribution. However, due to low-signal intensity, it is still challenging to obtain images of the fingerprint region, in which many spectrum peaks correspond to compositions of a cell. Here, to identify cell differentiation by using multiplex CARS, we investigated hyperspectral imaging of the fingerprint region of living cells. To perform multiplex CARS, we used a prototype of a compact light source generating both pump light and broadband Stokes light. Assuming application to regenerative medicine, we chose a cartilage cell, whose differentiation is difficult to be identified by change of the cell morphology. Because one of the major components of cartilage is collagen, we focused on distribution of proline, which accounts for approximately 20% of collagen. The spectrum quality was improved by optical adjustments of the power branching ratio and divergence of Stokes light. Periphery of a cartilage cell was highlighted in a CARS image of proline, and this result suggests correspondence with collagen generated as an extracellular matrix. The possibility of noninvasive analyses by using CARS hyperspectral imaging was indicated.

  9. Alkyne-Modulated Surface-Enhanced Raman Scattering-Palette for Optical Interference-Free and Multiplex Cellular Imaging.

    PubMed

    Chen, Yong; Ren, Jia-Qiang; Zhang, Xia-Guang; Wu, De-Yin; Shen, Ai-Guo; Hu, Ji-Ming

    2016-06-21

    The alkyne tags possess unique interference-free Raman emissions but are still hindered for further application in the field of biochemical labels due to its extremely weak spontaneous Raman scattering. With the aid of computational chemistry, herein, an alkyne-modulated surface-enhanced Raman scattering (SERS) palette is constructed based on rationally designed 4-ethynylbenzenethiol derivatives for spectroscopic signature, Au@Ag core for optical enhancement and an encapsulating polyallylamine shell for protection and conjugation. Even for the pigment rich plant cell (e.g., pollen), the alkyne-coded SERS tag can be highly discerned on two-dimension distribution impervious to strong organic interferences originating from resonance-enhanced Raman scattering or autofluorescence. In addition, the alkynyl-containing Raman reporters contribute especially narrow emission, band shift-tunable (2100-2300 cm(-1)) and tremendously enhanced Raman signals when the alkynyl group locates at para position of mercaptobenzene ring. Depending on only single Raman band, the suggested alkyne-modulated SERS-palette potentially provides a more effective solution for multiplex cellular imaging with vibrant colors, when the hyperspectral and fairly intense optical noises originating from lower wavenumber region (<1800 cm(-1)) are inevitable under complex ambient conditions. PMID:27223333

  10. Coherent Anti-Stokes Raman Scattering (CARS) Microscopy: A Novel Technique for Imaging the Retina

    PubMed Central

    Masihzadeh, Omid; Ammar, David A.; Kahook, Malik Y.; Lei, Tim C.

    2013-01-01

    Purpose. To image the cellular and noncellular structures of the retina in an intact mouse eye without the application of exogenous fluorescent labels using noninvasive, nondestructive techniques. Methods. Freshly enucleated mouse eyes were imaged using two nonlinear optical techniques: coherent anti-Stokes Raman scattering (CARS) and two-photon autofluorescence (TPAF). Cross sectional transverse sections and sequential flat (en face) sagittal sections were collected from a region of sclera approximately midway between the limbus and optic nerve. Imaging proceeded from the surface of the sclera to a depth of ∼60 μm. Results. The fluorescent signal from collagen fibers within the sclera was evident in the TPAF channel; the scleral collagen fibers showed no organization and appeared randomly packed. The sclera contained regions lacking TPAF and CARS fluorescence of ∼3 to 15 μm in diameter that could represent small vessels or scleral fibroblasts. Intense punctate CARS signals from the retinal pigment epithelial layer were of a size and shape of retinyl storage esters. Rod outer segments could be identified by the CARS signal from their lipid-rich plasma membranes. Conclusions. CARS microscopy can be used to image the outer regions of the mammalian retina without the use of a fluorescent dye or exogenously expressed recombinant protein. With technical advancements, CARS/TPAF may represent a new avenue for noninvasively imaging the retina and might complement modalities currently used in clinical practice. PMID:23580484

  11. Hyperspectral stimulated Raman scattering and multiphoton imaging for digital pathology of colonic disease

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

    Histopathology examinations of H&E stained biopsied tissues is the golden standard for colonic diseases (e.g., polyps, adenoma, and adenocarcinoma) diagnosis. However, staining effect of sample and doctor's expertise degree may greatly influence the diagnosis results. The information provided by the H&E stained sample is also limited to the morphological and PH information and no quantative information is available. In this paper, we report the development of a unique multimodal nonlinear optical microscopy (i.e., hyperspectral stimulated Raman scattering (hsSRS), second-harmonic generation (SHG), third-harmonic generation (THG), two-photon excitation fluorescence (TPEF)) platform for the diagnosis and characterization of colonic diseases. HsSRS in both fingerprint (800-1800 cm-1) and high-wavenumber (2800-3600 cm-1) regions allows us to discriminate different constituents with tiny difference in the Raman spectra. The increase of proteins and reduction of lipids could be observed with the progress of colonic cancer. SHG shows the distribution of collagen, which is found to aggregate for adenocarcinoma. TPEF provides the cell morphological and can reflect the damage inside glands caused by the diseases. THG shows the increase of optical heterogeneity related to cancer process. This work shows that the integrated hsSRS and TPEF/SHG/THG imaging technique can be an effective method for digital pathology of colonic diseases at the molecular and sub-cellular levels.

  12. Temperature imaging in nonpremixed flames by joint filtered Rayleigh and Raman scattering.

    PubMed

    Kearney, Sean P; Schefer, Robert W; Beresh, Steven J; Grasser, Thomas W

    2005-03-20

    Joint fuel Raman and filtered Rayleigh-scattering (FRS) imaging is demonstrated in a laminar methane-air diffusion flame. These experiments are, to our knowledge, the first reported extension of the FRS technique to nonpremixed combustion. This joint imaging approach allows for correction of the FRS images for the large variations in Rayleigh cross section that occur in diffusion flames and for a secondary measurement of fuel mole fraction. The temperature-dependent filtered Rayleigh cross sections are computed with a six-moment kinetic model for calculation of major-species Rayleigh-Brillouin line shapes and a flamelet-based model for physically judicious estimates of gas-phase chemical composition. Shot-averaged temperatures, fuel mole fractions, and fuel number densities from steady and vortex-strained diffusion flames stabilized on a Wolfhard-Parker slot burner are presented, and a detailed uncertainty analysis reveals that the FRS-measured temperatures are accurate to within +/- 4.5 to 6% of the local absolute temperature. PMID:15813256

  13. Three-dimensional chemical imaging of skin using stimulated Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

    Drutis, Dane M.; Hancewicz, Thomas M.; Pashkovski, Eugene; Feng, Lin; Mihalov, Dawn; Holtom, Gary; Ananthapadmanabhan, Kavssery P.; Xie, X. Sunney; Misra, Manoj

    2014-11-01

    Stimulated Raman scattering (SRS) microscopy is used to generate structural and chemical three-dimensional images of native skin. We employed SRS microscopy to investigate the microanatomical features of skin and penetration of topically applied materials. Image depth stacks are collected at distinct wavelengths corresponding to vibrational modes of proteins, lipids, and water in the skin. We observed that corneocytes in stratum corneum are grouped together in clusters, 100 to 250 μm in diameter, separated by 10- to 25-μm-wide microanatomical skin-folds called canyons. These canyons occasionally extend down to depths comparable to that of the dermal-epidermal junction below the flat surface regions in porcine and human skin. SRS imaging shows the distribution of chemical species within cell clusters and canyons. Water is predominately located within the cell clusters, and its concentration rapidly increases at the transition from stratum corneum to viable epidermis. Canyons do not contain detectable levels of water and are rich in lipid material. Oleic acid-d34 applied to the skin surface lines the canyons down to a depth of 50 μm below the surface of the skin. This observation could have implications on the evaluation of penetration profiles of bioactive materials measured using traditional methods, such as tape-stripping.

  14. Imaging Complex Protein Metabolism in Live Organisms by Stimulated Raman Scattering Microscopy with Isotope Labeling

    PubMed Central

    2016-01-01

    Protein metabolism, consisting of both synthesis and degradation, is highly complex, playing an indispensable regulatory role throughout physiological and pathological processes. Over recent decades, extensive efforts, using approaches such as autoradiography, mass spectrometry, and fluorescence microscopy, have been devoted to the study of protein metabolism. However, noninvasive and global visualization of protein metabolism has proven to be highly challenging, especially in live systems. Recently, stimulated Raman scattering (SRS) microscopy coupled with metabolic labeling of deuterated amino acids (D-AAs) was demonstrated for use in imaging newly synthesized proteins in cultured cell lines. Herein, we significantly generalize this notion to develop a comprehensive labeling and imaging platform for live visualization of complex protein metabolism, including synthesis, degradation, and pulse–chase analysis of two temporally defined populations. First, the deuterium labeling efficiency was optimized, allowing time-lapse imaging of protein synthesis dynamics within individual live cells with high spatial–temporal resolution. Second, by tracking the methyl group (CH3) distribution attributed to pre-existing proteins, this platform also enables us to map protein degradation inside live cells. Third, using two subsets of structurally and spectroscopically distinct D-AAs, we achieved two-color pulse–chase imaging, as demonstrated by observing aggregate formation of mutant hungtingtin proteins. Finally, going beyond simple cell lines, we demonstrated the imaging ability of protein synthesis in brain tissues, zebrafish, and mice in vivo. Hence, the presented labeling and imaging platform would be a valuable tool to study complex protein metabolism with high sensitivity, resolution, and biocompatibility for a broad spectrum of systems ranging from cells to model animals and possibly to humans. PMID:25560305

  15. Imaging complex protein metabolism in live organisms by stimulated Raman scattering microscopy with isotope labeling.

    PubMed

    Wei, Lu; Shen, Yihui; Xu, Fang; Hu, Fanghao; Harrington, Jamie K; Targoff, Kimara L; Min, Wei

    2015-03-20

    Protein metabolism, consisting of both synthesis and degradation, is highly complex, playing an indispensable regulatory role throughout physiological and pathological processes. Over recent decades, extensive efforts, using approaches such as autoradiography, mass spectrometry, and fluorescence microscopy, have been devoted to the study of protein metabolism. However, noninvasive and global visualization of protein metabolism has proven to be highly challenging, especially in live systems. Recently, stimulated Raman scattering (SRS) microscopy coupled with metabolic labeling of deuterated amino acids (D-AAs) was demonstrated for use in imaging newly synthesized proteins in cultured cell lines. Herein, we significantly generalize this notion to develop a comprehensive labeling and imaging platform for live visualization of complex protein metabolism, including synthesis, degradation, and pulse-chase analysis of two temporally defined populations. First, the deuterium labeling efficiency was optimized, allowing time-lapse imaging of protein synthesis dynamics within individual live cells with high spatial-temporal resolution. Second, by tracking the methyl group (CH3) distribution attributed to pre-existing proteins, this platform also enables us to map protein degradation inside live cells. Third, using two subsets of structurally and spectroscopically distinct D-AAs, we achieved two-color pulse-chase imaging, as demonstrated by observing aggregate formation of mutant hungtingtin proteins. Finally, going beyond simple cell lines, we demonstrated the imaging ability of protein synthesis in brain tissues, zebrafish, and mice in vivo. Hence, the presented labeling and imaging platform would be a valuable tool to study complex protein metabolism with high sensitivity, resolution, and biocompatibility for a broad spectrum of systems ranging from cells to model animals and possibly to humans. PMID:25560305

  16. Vibrational Imaging with High Sensitivity via Epidetected Coherent Anti-Stokes Raman Scattering Microscopy

    SciTech Connect

    Volkmer, Andreas; Cheng, Ji-Xin; Sunney Xie, X.

    2001-07-09

    We demonstrate theoretically and experimentally a novel epidetection scheme for coherent anti-Stokes Raman scattering (CARS) microscopy that significantly improves the detection sensitivity. Calculations show that epidetected CARS (E-CARS) signals are present for scatterers smaller than the wavelength of light, whereas the large background signals from the surrounding bulk solvent are suppressed by destructive interference. E-CARS microscopy is capable of revealing small intracellular features that are otherwise buried by the strong water CARS signal.

  17. Fiber bundle based probe with polarization for coherent anti-Stokes Raman scattering microendoscopy imaging

    NASA Astrophysics Data System (ADS)

    Liu, Zhengfan; Wang, Zhiyong; Wang, Xi; Xu, Xiaoyun; Chen, Xu; Cheng, Jie; Li, Xiaoyan; Chen, Shufen; Xin, Jianguo; Wong, Stephen T. C.

    2013-02-01

    The ability to visualize cellular structures and tissue molecular signatures in a live body could revolutionize the practice of surgery. Specifically, such technology is promising for replacing tissue extraction biopsy and offering new strategies for a broad range of intraoperative or surgical applications, including early cancer detection, tumor margin identification, nerve damage avoidance, and surgical outcomes enhancement. Coherent anti-Stokes Raman scattering (CARS) microendoscopy offers a way to achieve this with label-free imaging capability and sub-cellular resolution. However, efficient collection of epi-CARS signals and reduction of nonlinear effects in fibers are two major challenges encountered in the development of fiber-based CARS microendoscopy. To circumvent this problem, we designed and developed a fiber bundle for a CARS microendoscopy prototype. The excitation lasers were delivered by a single multimode fiber at the center of the bundle while the epi-CARS signals were collected by multiple MMFs surrounding the central fiber. A polarization scheme was employed to suppress the four-wave mixing (FWM) effect in the excitation fiber. Our experimental results suggest that, with this fiber bundle and the polarization FWM-suppressing scheme, the signal-to-noise ratio of the CARS images was greatly enhanced through a combination of high collection efficiency of epi-CARS signals, isolation of excitation lasers, and suppression of FWM. Tissue imaging capability of the microendoscopy prototype was demonstrated by ex vivo imaging on mouse skin and lung tissues. This fiber bundle-based CARS microendoscopy prototype, with the polarization FWM-suppressing scheme, offers a promising platform for constructing efficient fiber-based CARS microendoscopes for label free intraoperative imaging applications.

  18. Molded plasmonic crystals for detecting and spatially imaging surface bound species by surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Baca, Alfred J.; Truong, Tu T.; Cambrea, Lee R.; Montgomery, Jason M.; Gray, Stephen K.; Abdula, Daner; Banks, Tony R.; Yao, Jimin; Nuzzo, Ralph G.; Rogers, John A.

    2009-06-01

    This report introduces a type of plasmonic crystal that consists of metal coated nanostructures of relief molded on a polymer film as a substrate for surface-enhanced Raman scattering (SERS). Such crystals exhibit SERS enhancement factors of ˜105, over large areas and with sufficiently high levels of uniformity for precise two-dimensional Raman mapping of surface bound monolayers. The ease of fabrication together with the high sensitivities and spatial resolution that can be achieved suggests an attractive route to SERS substrates for portable chemical warfare agent detection, environmental monitors, noninvasive imaging of biomolecules, and other applications.

  19. Molded plasmonic crystals for detecting and spatially imaging surface bound species by surface-enhanced Raman scattering.

    SciTech Connect

    Baca, A. J.; Truong, T. T.; Cambrea, L. R.; Montgomery, J. M.; Abdula, D.; Banks, T. R.; Yao, J.; Nuzzo, R. G.; Gray, S. K.; Rogers, J. A.

    2009-06-24

    This report introduces a type of plasmonic crystal that consists of metal coated nanostructures of relief molded on a polymer film as a substrate for surface-enhanced Raman scattering (SERS). Such crystals exhibit SERS enhancement factors of {approx} 10{sup 5}, over large areas and with sufficiently high levels of uniformity for precise two-dimensional Raman mapping of surface bound monolayers. The ease of fabrication together with the high sensitivities and spatial resolution that can be achieved suggests an attractive route to SERS substrates for portable chemical warfare agent detection, environmental monitors, noninvasive imaging of biomolecules, and other applications.

  20. Stimulated Raman scattering holography for time-resolved imaging of methane gas.

    PubMed

    Amer, Eynas; Gren, Per; Edenharder, Stefan; Sjödahl, Mikael

    2016-05-01

    In this paper, pulsed digital holographic detection is coupled to the stimulated Raman scattering (SRS) process for imaging gases. A Q-switched Nd-YAG laser (532 nm) has been used to pump methane gas (CH4) at pressures up to 12 bars. The frequency-tripled (355 nm) beam from the same laser was used to pump an optical parametric oscillator (OPO). The Stokes beam (from the OPO) has been tuned to 629.93 nm so that the frequency difference between the pump (532 nm) and the Stokes beams fits a Raman active vibrational mode of the methane molecule (2922  cm-1). The pump beam has been spatially modulated with fringes produced in a Michelson interferometer. The pump and the Stokes beams were overlapped in time, space, and polarization on the gas molecules, resulting in a stimulated Raman gain of the Stokes beam and a corresponding loss of the pump beam through the SRS process. The resulting gain of the Stokes beam has been detected using pulsed digital holography by blending it with a reference beam on the detector. Two holograms of the Stokes beam, without and with the pump beam fringes present, were recorded. Intensity maps calculated from the recorded digital holograms showed amplification of the Stokes beam at the position of overlap with the pump beam fringes and the gas molecules. The gain of the Stokes beam has been separated from the background in the Fourier domain. A gain of about 4.5% at a pump beam average intensity of 4  MW/cm2 and a Stokes beam intensity of 0.16  MW/cm2 have been recorded at a gas pressure of 12 bars. The gain decreased linearly with decreasing gas pressure. The results show that SRS holography is a promising technique to pinpoint a specific species and record its spatial and temporal distribution. PMID:27140351

  1. Stimulated rotational Raman scattering

    NASA Astrophysics Data System (ADS)

    Parazzoli, C. G.; Rafanelli, G. L.; Capps, D. M.; Drutman, C.

    1989-03-01

    The effect of Stimulated Rotational Raman Scattering (SRRS) processes on high energy laser directed energy weapon systems was studied. The program had 3 main objectives; achieving an accurate description of the physical processes involved in SRRS; developing a numerical algorithm to confidently evaluate SRRS-induced losses in the propagation of high energy laser beams in the uplink and downlink segments of the optical trains of various strategic defense system scenarios; and discovering possible methods to eliminate, or at least reduce, the deleterious effects of SRRS on the energy deposition on target. The following topics are discussed: the motivation for the accomplishments of the DOE program; the Semiclassical Theory of Non-Resonant SRRS for Diatomic Homonuclear Molecules; and then the following appendices; Calculation of the Dipole Transition Reduced Matrix Element, Guided Tour of Hughes SRRS Code, Running the Hughes SRRS Code, and Hughes SRRS Code Listing.

  2. A new SERS: scattering enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Bixler, Joel N.; Yakovlev, Vladislav V.

    2014-03-01

    Raman spectroscopy is a powerful technique that can be used to obtain detailed chemical information about a system without the need for chemical markers. It has been widely used for a variety of applications such as cancer diagnosis and material characterization. However, Raman scattering is a highly inefficient process, where only one in 1011 scattered photons carry the needed information. Several methods have been developed to enhance this inherently weak effect, including surface enhanced Raman scattering and coherent anti-Stokes Raman scattering. These techniques suffer from drawbacks limiting their commercial use, such as the need for spatial localization of target molecules to a `hot spot', or the need for complex laser systems. Here, we present a simple instrument to enhance spontaneous Raman scattering using elastic light scattering. Elastic scattering is used to substantially increase the interaction volume. Provided that the scattering medium exhibits very low absorption in the spectral range of interest, a large enhancement factor can be attained in a simple and inexpensive setting. In our experiments, we demonstrate an enhancement of 107 in Raman signal intensity. The proposed novel device is equally applicable for analyzing solids, liquids, and gases.

  3. Stimulated Raman photoacoustic imaging

    PubMed Central

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

    2010-01-01

    Achieving label-free, molecular-specific imaging with high spatial resolution in deep tissue is often considered the grand challenge of optical imaging. To accomplish this goal, significant optical scattering in tissues has to be overcome while achieving molecular specificity without resorting to extrinsic labeling. We demonstrate the feasibility of developing such an optical imaging modality by combining the molecularly specific stimulated Raman excitation with the photoacoustic detection. By employing two ultrashort excitation laser pulses, separated in frequency by the vibrational frequency of a targeted molecule, only the specific vibrational level of the target molecules in the illuminated tissue volume is excited. This targeted optical absorption generates ultrasonic waves (referred to as stimulated Raman photoacoustic waves) which are detected using a traditional ultrasonic transducer to form an image following the design of the established photoacoustic microscopy. PMID:21059930

  4. Comparative Study of Breast Normal and Cancer Cells Using Coherent Anti-Stokes Raman Scattering Microspectroscopy Imaging

    NASA Astrophysics Data System (ADS)

    Lee, Jang Hyuk; Cho, Eun Hee; Shin, Sang-Mo; Oh, Myoung-kyu; Ko, Do-Kyeong

    2012-08-01

    A coherent anti-Stokes Raman scattering (CARS) microspectroscopy imaging system was developed using a femtosecond laser and a photonic crystal fiber (PCF). We separated resonant and non-resonant CARS signals in the time domain by the chirp of the PCF, and applied this system to compare live human breast normal and cancer cells. The CARS image and spectrum at C-H stretch vibration in lipid droplets could subsequently be used to differentiate cancer cells from normal cells, thereby confirming the potential of the CARS microspectroscopy imaging system as a diagnostic tool that allows the high-sensitivity, high-resolution, and fast detection of breast cancer.

  5. Surface-Enhanced Raman Scattering Active Plasmonic Nanoparticles with Ultrasmall Interior Nanogap for Multiplex Quantitative Detection and Cancer Cell Imaging.

    PubMed

    Li, Jiuxing; Zhu, Zhi; Zhu, Bingqing; Ma, Yanli; Lin, Bingqian; Liu, Rudi; Song, Yanling; Lin, Hui; Tu, Song; Yang, Chaoyong

    2016-08-01

    Due to its large enhancement effect, nanostructure-based surface-enhanced Raman scattering (SERS) technology had been widely applied for bioanalysis and cell imaging. However, most SERS nanostructures suffer from poor signal reproducibility, which hinders the application of SERS nanostructures in quantitative detection. We report an etching-assisted approach to synthesize SERS-active plasmonic nanoparticles with 1 nm interior nanogap for multiplex quantitative detection and cancer cell imaging. Raman dyes and methoxy poly(ethylene glycol) thiol (mPEG-SH) were attached to gold nanoparticles (AuNPs) to prepare gold cores. Next, Ag atoms were deposited on gold cores in the presence of Pluronic F127 to form a Ag shell. HAuCl4 was used to etch the Ag shell and form an interior nanogap in Au@AgAuNPs, leading to increased Raman intensity of dyes. SERS intensity distribution of Au@AgAuNPs was found to be more uniform than that of aggregated AuNPs. Finally, Au@AgAuNPs were used for multiplex quantitative detection and cancer cell imaging. With the advantages of simple and rapid preparation of Au@AgAuNPs with highly uniform, stable, and reproducible Raman intensity, the method reported here will widen the applications of SERS-active nanoparticles in diagnostics and imaging. PMID:27385563

  6. Polarization-resolved hyperspectral stimulated Raman scattering microscopy for label-free biomolecular imaging of the tooth

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Zheng, Wei; Hsu, Chin-Ying Stephen; Huang, Zhiwei

    2016-01-01

    We report the development and implementation of a rapid polarization-resolved hyperspectral stimulated Raman scattering (SRS) microscopy technique for label-free biomolecular imaging of the tooth. The hyperspectral SRS imaging technique developed covers both fingerprint (800-1800 cm-1) and high-wavenumber (2800-3600 cm-1) regions for tooth Raman imaging without fluorescence background interference with an imaging speed of <0.3 s per frame of 512 × 512 pixels (˜1 μs per pixel), that is, >106 faster than confocal Raman imaging. Significant differences of hyperspectral SRS spectra among different tooth locations (e.g., dentin, enamel, and dentin-enamel junction) are observed, revealing the biochemical distribution differences across the tooth. Further polarization-resolved SRS imaging shows different polarization dependences related to the molecular orientation differences of various tooth locations. This work demonstrates the potential of polarization-resolved hyperspectral SRS imaging technique developed in rapidly characterizing biochemical structures and compositions as well as biomolecule organizations/orientations of the tooth without labeling.

  7. New imaging-based biomarkers for melanoma diagnosis using coherent Raman Scattering microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Wang, Hequn; Osseiran, Sam; Roider, Elisabeth; Fisher, David E.; Evans, Conor L.

    2016-02-01

    Recently, pheomelanin has been found to play a critical role in melanoma progression given its pro-oxidant chemical properties as well as its marked presence in pre-cancerous and malignant melanoma lesions, even in the absence of ultraviolet radiation. In addition, epidemiological evidence indicates a strong correlation between melanoma incidence and skin type, with the highest incidence occurring in individuals of the red-haired/fair-skinned phenotype. Interestingly, nevus count correlates well with melanoma incidence and skin type, except in the population most prone to developing melanoma, where nevus count strikingly drops. As such, a current hypothesis proposes that fair-skinned red-haired individuals, who are unable to stimulate production of eumelanin due to a mutation in MC1R in melanocytes, may actually harbor numerous "invisible", pheomelanin-rich nevi that evade clinical detection, supporting the high incidence of melanoma in that population. Here, we show for the very first time that melanocytes extracted from genetically modified MC1R-mutant, red-haired mice displayed bright perinuclear distributions of signal within the cells under coherent anti-Stokes Raman scattering (CARS) microscopy. Changes in pheomelanin production in siRNA knockdowns of cultured human melanoma cells were also sensed. We then successfully imaged pheomelanin distributions in both ex vivo and in vivo mouse ear skin. Finally, melanosomes within amelanotic melanoma patient tissue sections were found to show bright pheomelanin signals. This is the first time, to our knowledge, that pheomelanin has been found spatially localized in a human amelanotic melanoma sample. These pheomelanotic CARS features may be used as potential biomarkers for melanoma detection, especially for amelanotic melanomas.

  8. Rotational coherence imaging and control for CN molecules through time-frequency resolved coherent anti-Stokes Raman scattering.

    PubMed

    Lindgren, Johan; Hulkko, Eero; Pettersson, Mika; Kiljunen, Toni

    2011-12-14

    Numerical wave packet simulations are performed for studying coherent anti-Stokes Raman scattering (CARS) for CN radicals. Electronic coherence is created by femtosecond laser pulses between the X(2)Σ and B(2)Σ states. Due to the large energy separation of vibrational states, the wave packets are superpositions of rotational states only. This allows for a specially detailed inspection of the second- and third-order coherences by a two-dimensional imaging approach. We present the time-frequency domain images to illustrate the intra- and intermolecular interferences, and discuss the procedure to rationally control and experimentally detect the interferograms in solid Xe environment. PMID:22168710

  9. Assessing Cholesterol Storage in Live Cells and C. elegans by Stimulated Raman Scattering Imaging of Phenyl-Diyne Cholesterol

    PubMed Central

    Lee, Hyeon Jeong; Zhang, Wandi; Zhang, Delong; Yang, Yang; Liu, Bin; Barker, Eric L.; Buhman, Kimberly K.; Slipchenko, Lyudmila V.; Dai, Mingji; Cheng, Ji-Xin

    2015-01-01

    We report a cholesterol imaging method using rationally synthesized phenyl-diyne cholesterol (PhDY-Chol) and stimulated Raman scattering (SRS) microscope. The phenyl-diyne group is biologically inert and provides a Raman scattering cross section that is 88 times larger than the endogenous C = O stretching mode. SRS microscopy offers an imaging speed that is faster than spontaneous Raman microscopy by three orders of magnitude, and a detection sensitivity of 31 μM PhDY-Chol (~1,800 molecules in the excitation volume). Inside living CHO cells, PhDY-Chol mimics the behavior of cholesterol, including membrane incorporation and esterification. In a cellular model of Niemann-Pick type C disease, PhDY-Chol reflects the lysosomal accumulation of cholesterol, and shows relocation to lipid droplets after HPβCD treatment. In live C. elegans, PhDY-Chol mimics cholesterol uptake by intestinal cells and reflects cholesterol storage. Together, our work demonstrates an enabling platform for study of cholesterol storage and trafficking in living cells and vital organisms. PMID:25608867

  10. Assessing Cholesterol Storage in Live Cells and C. elegans by Stimulated Raman Scattering Imaging of Phenyl-Diyne Cholesterol

    NASA Astrophysics Data System (ADS)

    Lee, Hyeon Jeong; Zhang, Wandi; Zhang, Delong; Yang, Yang; Liu, Bin; Barker, Eric L.; Buhman, Kimberly K.; Slipchenko, Lyudmila V.; Dai, Mingji; Cheng, Ji-Xin

    2015-01-01

    We report a cholesterol imaging method using rationally synthesized phenyl-diyne cholesterol (PhDY-Chol) and stimulated Raman scattering (SRS) microscope. The phenyl-diyne group is biologically inert and provides a Raman scattering cross section that is 88 times larger than the endogenous C = O stretching mode. SRS microscopy offers an imaging speed that is faster than spontaneous Raman microscopy by three orders of magnitude, and a detection sensitivity of 31 μM PhDY-Chol (~1,800 molecules in the excitation volume). Inside living CHO cells, PhDY-Chol mimics the behavior of cholesterol, including membrane incorporation and esterification. In a cellular model of Niemann-Pick type C disease, PhDY-Chol reflects the lysosomal accumulation of cholesterol, and shows relocation to lipid droplets after HPβCD treatment. In live C. elegans, PhDY-Chol mimics cholesterol uptake by intestinal cells and reflects cholesterol storage. Together, our work demonstrates an enabling platform for study of cholesterol storage and trafficking in living cells and vital organisms.

  11. Texture analysis and classification in coherent anti-Stokes Raman scattering (CARS) microscopy images for automated detection of skin cancer.

    PubMed

    Legesse, Fisseha Bekele; Medyukhina, Anna; Heuke, Sandro; Popp, Jürgen

    2015-07-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy is a powerful tool for fast label-free tissue imaging, which is promising for early medical diagnostics. To facilitate the diagnostic process, automatic image analysis algorithms, which are capable of extracting relevant features from the image content, are needed. In this contribution we perform an automated classification of healthy and tumor areas in CARS images of basal cell carcinoma (BCC) skin samples. The classification is based on extraction of texture features from image regions and subsequent classification of these regions into healthy and cancerous with a perceptron algorithm. The developed approach is capable of an accurate classification of texture types with high sensitivity and specificity, which is an important step towards an automated tumor detection procedure. PMID:25797604

  12. Chemical imaging with frequency modulation coherent anti-Stokes Raman scattering microscopy at the vibrational fingerprint region.

    PubMed

    Chen, Bi-Chang; Sung, Jiha; Lim, Sang-Hyun

    2010-12-23

    We present a new coherent anti-Stokes Raman scattering (CARS) method that can perform background-free microscopy and microspectroscopy at the vibrational fingerprint region. Chirped broad-band pulses from a single Ti:sapphire laser generate CARS signals over 800-1700 cm(-1) with a spectral resolution of 20 cm(-1). Fast modulation of the time delay between the pump and Stokes pulses coupled with lock-in signal detection not only removes the nonresonant background but also produces Raman-like CARS signals. Chemical imaging and microspectroscopy are demonstrated with various samples such as edible oils, lipid membranes, skin tissue, and plant cell walls. Systematic studies of the signal generation mechanism and several fundamental aspects are discussed. PMID:21126030

  13. Integrated coherent Raman scattering and multiphoton microscopy for label-free imaging of the dentin in the tooth

    NASA Astrophysics Data System (ADS)

    Wang, Zi; Zheng, Wei; Lin, Jian; Hsu, Chin-Ying; Huang, Zhiwei

    2014-02-01

    We report the implementation of a unique multimodal nonlinear optical microscopy (i.e., coherent anti-Stokes Raman scattering (CARS), second harmonic generation (SHG), third harmonic generation (THG) and two photon excitation fluorescence (TPEF)) platform for label-free imaging of dentin. A picosecond tunable laser together with an OPO is used as the excitation source for simultaneously multimodal imaging. CARS shows similar information as TPEF in dentin, but it has a higher sectioning performance than TPEF and thus it is a good alternative for TPEF. Microtubule structure is revealed nearby dentin enamel junction (DEJ) from the multimodal images. This work demonstrates that combining different nonlinear optical imaging modalities can provide new insights into the understanding of morphological structures and biochemical/biomolecular distributions of the dentine without the need of labeling.

  14. Nonlinear optical interference of two successive coherent anti-Stokes Raman scattering signals for biological imaging applications.

    PubMed

    Lee, Eun Seong; Lee, Jae Yong; Yoo, Yong Shim

    2007-01-01

    The nonlinear optical interference of two successively generated coherent anti-Stokes Raman scattering (CARS) signals from two different samples placed in series is demonstrated for the imaging performance, in which a collinear phase matching geometry is used. The relative phase of two CARS signals is controlled by a phase-shifting unit made of dispersive glass materials of which the thickness can be precisely varied. The clear interference fringes are observed as the thickness of the phase-shifting unit changes. The interference effect is then utilized to achieve a better quality CARS image of a biological tissue taken from a mouse skin. Placing the tissue in the second sample position and performing raster scans of the laser beams on it, we can acquire a CARS image of higher contrast compared to the normal image obtained without interferometric implementation. PMID:17477725

  15. Longitudinal in vivo coherent anti-Stokes Raman scattering imaging of demyelination and remyelination in injured spinal cord

    NASA Astrophysics Data System (ADS)

    Shi, Yunzhou; Zhang, Delong; Huff, Terry B.; Wang, Xiaofei; Shi, Riyi; Xu, Xiao-Ming; Cheng, Ji-Xin

    2011-10-01

    In vivo imaging of white matter is important for the mechanistic understanding of demyelination and evaluation of remyelination therapies. Although white matter can be visualized by a strong coherent anti-Stokes Raman scattering (CARS) signal from axonal myelin, in vivo repetitive CARS imaging of the spinal cord remains a challenge due to complexities induced by the laminectomy surgery. We present a careful experimental design that enabled longitudinal CARS imaging of de- and remyelination at single axon level in live rats. In vivo CARS imaging of secretory phospholipase A2 induced myelin vesiculation, macrophage uptake of myelin debris, and spontaneous remyelination by Schwann cells are sequentially monitored over a 3 week period. Longitudinal visualization of de- and remyelination at a single axon level provides a novel platform for rational design of therapies aimed at promoting myelin plasticity and repair.

  16. Raman scattering in cuprate superconductors

    SciTech Connect

    Devereaux, T.P.; Kampf, A.P.

    1997-07-20

    A theory for electronic Raman scattering in the cuprate superconductors is presented with a specific emphasis on the polarization dependence of the spectra which can infer the symmetry of the energy gap. Signatures of the effects of disorder on the low frequency and low temperature behavior of the Raman spectra for different symmetry channels provide detailed information about the magnitude and the phase of the energy gap. Properties of the theory for finite T will be discussed and compared to recent data concerning the doping dependence of the Raman spectra in cuprate superconductors, and remaining questions will be addressed.

  17. A Real-Time Clinical Endoscopic System for Intraluminal, Multiplexed Imaging of Surface-Enhanced Raman Scattering Nanoparticles

    PubMed Central

    Garai, Ellis; Loewke, Nathan O.; Rogalla, Stephan; Mandella, Michael J.; Felt, Stephen A.; Friedland, Shai; Liu, Jonathan T. C.; Gambhir, Sanjiv S.; Contag, Christopher H.

    2015-01-01

    The detection of biomarker-targeting surface-enhanced Raman scattering (SERS) nanoparticles (NPs) in the human gastrointestinal tract has the potential to improve early cancer detection; however, a clinically relevant device with rapid Raman-imaging capability has not been described. Here we report the design and in vivo demonstration of a miniature, non-contact, opto-electro-mechanical Raman device as an accessory to clinical endoscopes that can provide multiplexed molecular data via a panel of SERS NPs. This device enables rapid circumferential scanning of topologically complex luminal surfaces of hollow organs (e.g., colon and esophagus) and produces quantitative images of the relative concentrations of SERS NPs that are present. Human and swine studies have demonstrated the speed and simplicity of this technique. This approach also offers unparalleled multiplexing capabilities by simultaneously detecting the unique spectral fingerprints of multiple SERS NPs. Therefore, this new screening strategy has the potential to improve diagnosis and to guide therapy by enabling sensitive quantitative molecular detection of small and otherwise hard-to-detect lesions in the context of white-light endoscopy. PMID:25923788

  18. Increasing the imaging depth of coherent anti-Stokes Raman scattering microscopy with a miniature microscope objective

    NASA Astrophysics Data System (ADS)

    Wang, Haifeng; Huff, Terry B.; Fu, Yan; Jia, Kevin Y.; Cheng, Ji-Xin

    2007-08-01

    A miniature objective lens with a tip diameter of 1.3 mm was used for extending the penetration depth of coherent anti-Stokes Raman scattering (CARS) microscopy. Its axial and lateral focal widths were determined to be 11.4 and 0.86 μm, respectively, by two-photon excitation fluorescence imaging of 200 nm beads at a 735 nm excitation wavelength. By inserting the lens tip into a soft gel sample, CARS images of 2 μm polystyrene beads 5 mm deep from the surface were acquired. The miniature objective was applied to CARS imaging of rat spinal cord white matter with a minimal requirement for surgery.

  19. Live-cell vibrational imaging of choline metabolites by stimulated Raman scattering coupled with isotope-based metabolic labeling

    PubMed Central

    Hu, Fanghao; Wei, Lu; Zheng, Chaogu; Shen, Yihui

    2014-01-01

    Choline is a small molecule that occupies a key position in the biochemistry of all living organisms. Recent studies have strongly implicated choline metabolites in cancer, atherosclerosis and nervous system development. To detect choline and its metabolites, existing physical methods such as magnetic resonance spectroscopy and positron emission tomography, are often limited by the poor spatial resolution and substantial radiation dose. Fluorescence imaging, although with submicrometer resolution, requires introduction of bulky fluorophores and thus is difficult in labeling the small choline molecule. By combining the emerging bond-selective stimulated Raman scattering microscopy with metabolic incorporation of deuterated choline, herein we have achieved high resolution imaging of choline-containing metabolites in living mammalian cell lines, primary hippocampal neurons and multicellular organism C. elegans. Different subcellular distributions of choline metabolites are observed between cancer cells and non-cancer cells, which may reveal functional difference in the choline metabolism and lipid-mediated signaling events. In neurons, choline incorporation is visualized within both soma and neurites, where choline metabolites are more evenly distributed compared to the protein. Furthermore, choline localization is also observed in the pharynx region of C. elegans larvae, consistent with its organogenesis mechanism. These applications demonstrate the potential of isotope-based stimulated Raman scattering microscopy for future choline-related disease detection and development monitoring in vivo. PMID:24555181

  20. Characterization of conductive nanobiomaterials derived from viral assemblies by low-voltage STEM imaging and Raman scattering

    NASA Astrophysics Data System (ADS)

    Plascencia-Villa, Germán; Carreño-Fuentes, Liliana; Bahena, Daniel; José-Yacamán, Miguel; Palomares, Laura A.; Ramírez, Octavio T.

    2014-09-01

    New technologies require the development of novel nanomaterials that need to be fully characterized to achieve their potential. High-resolution low-voltage scanning transmission electron microscopy (STEM) has proven to be a very powerful technique in nanotechnology, but its use for the characterization of nanobiomaterials has been limited. Rotavirus VP6 self-assembles into nanotubular assemblies that possess an intrinsic affinity for Au ions. This property was exploited to produce hybrid nanobiomaterials by the in situ functionalization of recombinant VP6 nanotubes with gold nanoparticles. In this work, Raman spectroscopy and advanced analytical electron microscopy imaging with spherical aberration-corrected (Cs) STEM and nanodiffraction at low-voltage doses were employed to characterize nanobiomaterials. STEM imaging revealed the precise structure and arrangement of the protein templates, as well as the nanostructure and atomic arrangement of gold nanoparticles with high spatial sub-Angstrom resolution and avoided radiation damage. The imaging was coupled with backscattered electron imaging, ultra-high resolution scanning electron microscopy and x-ray spectroscopy. The hybrid nanobiomaterials that were obtained showed unique properties as bioelectronic conductive devices and showed enhanced Raman scattering by their precise arrangement into superlattices, displaying the utility of viral assemblies as functional integrative self-assembled nanomaterials for novel applications.

  1. Plasmon Mapping in Metallic Nanostructures and its Application to Single Molecule Surface Enhanced Raman Scattering: Imaging Electromagnetic Hot-Spots and Analyte Location

    SciTech Connect

    Camden, Jon P

    2013-07-16

    A major component of this proposal is to elucidate the connection between optical and electron excitation of plasmon modes in metallic nanostructures. These accomplishments are reported: developed a routine protocol for obtaining spatially resolved, low energy EELS spectra, and resonance Rayleigh scattering spectra from the same nanostructures.; correlated optical scattering spectra and plasmon maps obtained using STEM/EELS.; and imaged electromagnetic hot spots responsible for single-molecule surface-enhanced Raman scattering (SMSERS).

  2. Theory of Graphene Raman Scattering.

    PubMed

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

    2016-02-23

    Raman scattering plays a key role in unraveling the quantum dynamics of graphene, perhaps the most promising material of recent times. It is crucial to correctly interpret the meaning of the spectra. It is therefore very surprising that the widely accepted understanding of Raman scattering, i.e., Kramers-Heisenberg-Dirac theory, has never been applied to graphene. Doing so here, a remarkable mechanism we term"transition sliding" is uncovered, explaining the uncommon brightness of overtones in graphene. Graphene's dispersive and fixed Raman bands, missing bands, defect density and laser frequency dependence of band intensities, widths of overtone bands, Stokes, anti-Stokes anomalies, and other known properties emerge simply and directly. PMID:26799915

  3. Coherent anti-Stokes Raman scattering microscopy driving the future of loaded mesoporous silica imaging.

    PubMed

    Fussell, Andrew L; Mah, Pei Ting; Offerhaus, Herman; Niemi, Sanna-Mari; Salonen, Jarno; Santos, Hélder A; Strachan, Clare

    2014-11-01

    This study reports the use of variants of coherent anti-Stokes Raman scattering (CARS) microscopy as a novel method for improved physicochemical characterization of drug-loaded silica particles. Ordered mesoporous silica is a biomaterial that can be loaded to carry a number of biochemicals, including poorly water-soluble drugs, by allowing the incorporation of drug into nanometer-sized pores. In this work, the loading of two poorly water-soluble model drugs, itraconazole and griseofulvin, in MCM-41 silica microparticles is characterized qualitatively, using the novel approach of CARS microscopy, which has advantages over other analytical approaches used to date and is non-destructive, rapid, label free, confocal and has chemical and physical specificity. The study investigated the effect of two solvent-based loading methods, namely immersion and rotary evaporation, and microparticle size on the three-dimensional (3-D) distribution of the two loaded drugs. Additionally, hyperspectral CARS microscopy was used to confirm the amorphous nature of the loaded drugs. Z-stacked CARS microscopy suggested that the drug, but not the loading method or particle size range, affected 3-D drug distribution. Hyperspectral CARS confirmed that the drug loaded in the MCM-41 silica microparticles was in an amorphous form. The results show that CARS microscopy and hyperspectral CARS microscopy can be used to provide further insights into the structural nature of loaded mesoporous silica microparticles as biomaterials. PMID:25064000

  4. Ex vivo and in vivo imaging of myelin fibers in mouse brain by coherent anti-Stokes Raman scattering microscopy

    PubMed Central

    Fu, Yan; Huff, T. Brandon; Wang, Han-Wei; Wang, Haifeng; Cheng, Ji-Xin

    2009-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy was applied to image myelinated fibers in different regions of a mouse brain. The CARS signal from the CH2 symmetric stretching vibration allows label-free imaging of myelin sheath with 3D sub-micron resolution. Compared with two-photon excited fluorescence imaging with lipophilic dye labeling, CARS microscopy provides sharper contrast and avoids photobleaching. The CARS signal exhibits excitation polarization dependence which can be eliminated by reconstruction of two complementary images with perpendicular excitation polarizations. The capability of imaging myelinated fibers without exogenous labeling was used to map the whole brain white matter in brain slices and to analyze the microstructural anatomy of brain axons. Quantitative information about fiber volume%, myelin density, and fiber orientations was derived. Combining CARS with two-photon excited fluorescence allowed multimodal imaging of myelinated axons and other cells. Furthermore, in vivo CARS imaging on an upright microscope clearly identified fiber bundles in brain subcortex white matter. These advances open up new opportunities for the study of brain connectivity and neurological disorders. PMID:19030027

  5. Novel nitrocellulose membrane substrate for efficient analysis of circulating tumor cells coupled with surface-enhanced Raman scattering imaging.

    PubMed

    Zhang, Peng; Zhang, Ren; Gao, Mingxia; Zhang, Xiangmin

    2014-01-01

    The capture and detection of circulating tumor cells (CTCs) in the bloodstream of patients with cancer is crucial for the clinical diagnosis and therapy. In the present work, a facile and integrated approach based on novel nitrocellulose membrane substrate and large-scale surface-enhanced Raman scattering (SERS) imaging technology has been developed for CTCs' sensitive detection and enumeration. The system mainly consists of three aspects: capture of CTCs in bloodstream, SERS probes labeling of the captured CTCs and large-scale SERS imaging readout of CTCs enumeration. The NC membrane was used to prepare the novel CTC-capture substrate through antibody self-assembled. It was low-cost, easily prepared and completely nontoxic. Furthermore, excellent capture efficiency of the substrate was demonstrated using nonsmall-cell lung cancer (NSCLC) cells (NCI-H1650) as target cells. As the most sensitive detection technology, SERS holds huge potential in CTCs analysis. Large-scale SERS imaging was employed in CTCs enumeration for the first time, instead of the conventional fluorescence imaging. Our SERS probes, with a simplified structure, offered highly enough sensitivity to recognize every single cell clearly. In the simulation experiment of spiking 100 cancer cells into 1 mL of human whole blood, 34 cells were captured and counted successfully according to the SERS imaging result. Our experimental results demonstrate the potential feasibility of novel NC membrane substrate coupled with large-scale SERS imaging technology for the accurate enumeration of CTCs in human whole blood. PMID:24325273

  6. Penetration of silver nanoparticles into porcine skin ex vivo using fluorescence lifetime imaging microscopy, Raman microscopy, and surface-enhanced Raman scattering microscopy.

    PubMed

    Zhu, Yongjian; Choe, Chun-Sik; Ahlberg, Sebastian; Meinke, Martina C; Alexiev, Ulrike; Lademann, Juergen; Darvin, Maxim E

    2015-05-01

    In order to investigate the penetration depth of silver nanoparticles (Ag NPs) inside the skin, porcine ears treated with Ag NPs are measured by two-photon tomography with a fluorescence lifetime imaging microscopy (TPT-FLIM) technique, confocal Raman microscopy (CRM), and surface-enhanced Raman scattering (SERS) microscopy. Ag NPs are coated with poly-N-vinylpyrrolidone and dispersed in pure water solutions. After the application of Ag NPs, porcine ears are stored in the incubator for 24 h at a temperature of 37°C. The TPT-FLIM measurement results show a dramatic decrease of the Ag NPs' signal intensity from the skin surface to a depth of 4 μm. Below 4 μm, the Ag NPs' signal continues to decline, having completely disappeared at 12 to 14 μm depth. CRM shows that the penetration depth of Ag NPs is 11.1 ± 2.1 μm. The penetration depth measured with a highly sensitive SERS microscopy reaches 15.6 ± 8.3 μm. Several results obtained with SERS show that the penetration depth of Ag NPs can exceed the stratum corneum (SC) thickness, which can be explained by both penetration of trace amounts of Ag NPs through the SC barrier and by the measurements inside the hair follicle, which cannot be excluded in the experiment. PMID:25394476

  7. Penetration of silver nanoparticles into porcine skin ex vivo using fluorescence lifetime imaging microscopy, Raman microscopy, and surface-enhanced Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

    Zhu, Yongjian; Choe, Chun-Sik; Ahlberg, Sebastian; Meinke, Martina C.; Alexiev, Ulrike; Lademann, Juergen; Darvin, Maxim E.

    2015-05-01

    In order to investigate the penetration depth of silver nanoparticles (Ag NPs) inside the skin, porcine ears treated with Ag NPs are measured by two-photon tomography with a fluorescence lifetime imaging microscopy (TPT-FLIM) technique, confocal Raman microscopy (CRM), and surface-enhanced Raman scattering (SERS) microscopy. Ag NPs are coated with poly-N-vinylpyrrolidone and dispersed in pure water solutions. After the application of Ag NPs, porcine ears are stored in the incubator for 24 h at a temperature of 37°C. The TPT-FLIM measurement results show a dramatic decrease of the Ag NPs' signal intensity from the skin surface to a depth of 4 μm. Below 4 μm, the Ag NPs' signal continues to decline, having completely disappeared at 12 to 14 μm depth. CRM shows that the penetration depth of Ag NPs is 11.1±2.1 μm. The penetration depth measured with a highly sensitive SERS microscopy reaches 15.6±8.3 μm. Several results obtained with SERS show that the penetration depth of Ag NPs can exceed the stratum corneum (SC) thickness, which can be explained by both penetration of trace amounts of Ag NPs through the SC barrier and by the measurements inside the hair follicle, which cannot be excluded in the experiment.

  8. Imaging of lipids in microalgae with coherent anti-stokes Raman scattering microscopy.

    PubMed

    Cavonius, Lillie; Fink, Helen; Kiskis, Juris; Albers, Eva; Undeland, Ingrid; Enejder, Annika

    2015-03-01

    Microalgae have great prospects as a sustainable resource of lipids for refinement into nutraceuticals and biodiesel, which increases the need for detailed insights into their intracellular lipid synthesis/storage mechanisms. As an alternative strategy to solvent- and label-based lipid quantification techniques, we introduce time-gated coherent anti-Stokes Raman scattering (CARS) microscopy for monitoring lipid contents in living algae, despite strong autofluorescence from the chloroplasts, at approximately picogram and subcellular levels by probing inherent molecular vibrations. Intracellular lipid droplet synthesis was followed in Phaeodactylum tricornutum algae grown under (1) light/nutrient-replete (control [Ctrl]), (2) light-limited (LL), and (3) nitrogen-starved (NS) conditions. Good correlation (r(2) = 0.924) was found between lipid volume data yielded by CARS microscopy and total fatty acid content obtained from gas chromatography-mass spectrometry analysis. In Ctrl and LL cells, micron-sized lipid droplets were found to increase in number throughout the growth phases, particularly in the stationary phase. During more excessive lipid accumulation, as observed in NS cells, promising commercial harvest as biofuels and nutritional lipids, several micron-sized droplets were present already initially during cultivation, which then fused into a single giant droplet toward stationary phase alongside with new droplets emerging. CARS microspectroscopy further indicated lower lipid fluidity in NS cells than in Ctrl and LL cells, potentially due to higher fatty acid saturation. This agreed with the fatty acid profiles gathered by gas chromatography-mass spectrometry. CARS microscopy could thus provide quantitative and semiqualitative data at the single-cell level along with important insights into lipid-accumulating mechanisms, here revealing two different modes for normal and excessive lipid accumulation. PMID:25583924

  9. Imaging of Lipids in Microalgae with Coherent Anti-Stokes Raman Scattering Microscopy1[OPEN

    PubMed Central

    Cavonius, Lillie; Fink, Helen; Kiskis, Juris; Albers, Eva; Undeland, Ingrid; Enejder, Annika

    2015-01-01

    Microalgae have great prospects as a sustainable resource of lipids for refinement into nutraceuticals and biodiesel, which increases the need for detailed insights into their intracellular lipid synthesis/storage mechanisms. As an alternative strategy to solvent- and label-based lipid quantification techniques, we introduce time-gated coherent anti-Stokes Raman scattering (CARS) microscopy for monitoring lipid contents in living algae, despite strong autofluorescence from the chloroplasts, at approximately picogram and subcellular levels by probing inherent molecular vibrations. Intracellular lipid droplet synthesis was followed in Phaeodactylum tricornutum algae grown under (1) light/nutrient-replete (control [Ctrl]), (2) light-limited (LL), and (3) nitrogen-starved (NS) conditions. Good correlation (r2 = 0.924) was found between lipid volume data yielded by CARS microscopy and total fatty acid content obtained from gas chromatography-mass spectrometry analysis. In Ctrl and LL cells, micron-sized lipid droplets were found to increase in number throughout the growth phases, particularly in the stationary phase. During more excessive lipid accumulation, as observed in NS cells, promising commercial harvest as biofuels and nutritional lipids, several micron-sized droplets were present already initially during cultivation, which then fused into a single giant droplet toward stationary phase alongside with new droplets emerging. CARS microspectroscopy further indicated lower lipid fluidity in NS cells than in Ctrl and LL cells, potentially due to higher fatty acid saturation. This agreed with the fatty acid profiles gathered by gas chromatography-mass spectrometry. CARS microscopy could thus provide quantitative and semiqualitative data at the single-cell level along with important insights into lipid-accumulating mechanisms, here revealing two different modes for normal and excessive lipid accumulation. PMID:25583924

  10. Integrated femtosecond stimulated Raman scattering and two-photon fluorescence imaging of subcellular lipid and vesicular structures

    NASA Astrophysics Data System (ADS)

    Li, Xuesong; Lam, Wen Jiun; Cao, Zhe; Hao, Yan; Sun, Qiqi; He, Sicong; Mak, Ho Yi; Qu, Jianan Y.

    2015-11-01

    The primary goal of this study is to demonstrate that stimulated Raman scattering (SRS) as a new imaging modality can be integrated into a femtosecond (fs) nonlinear optical (NLO) microscope system. The fs sources of high pulse peak power are routinely used in multimodal nonlinear microscopy to enable efficient excitation of multiple NLO signals. However, with fs excitations, the SRS imaging of subcellular lipid and vesicular structures encounters significant interference from proteins due to poor spectral resolution and a lack of chemical specificity, respectively. We developed a unique NLO microscope of fs excitation that enables rapid acquisition of SRS and multiple two-photon excited fluorescence (TPEF) signals. In the in vivo imaging of transgenic C. elegans animals, we discovered that by cross-filtering false positive lipid signals based on the TPEF signals from tryptophan-bearing endogenous proteins and lysosome-related organelles, the imaging system produced highly accurate assignment of SRS signals to lipid. Furthermore, we demonstrated that the multimodal NLO microscope system could sequentially image lipid structure/content and organelles, such as mitochondria, lysosomes, and the endoplasmic reticulum, which are intricately linked to lipid metabolism.

  11. Chemical imaging of tissue in vivo with video-rate coherent anti-Stokes Raman scattering microscopy

    PubMed Central

    Evans, Conor L.; Potma, Eric O.; Puoris'haag, Mehron; Côté, Daniel; Lin, Charles P.; Xie, X. Sunney

    2005-01-01

    Imaging living organisms with molecular selectivity typically requires the introduction of specific labels. Many applications in biology and medicine, however, would significantly benefit from a noninvasive imaging technique that circumvents such exogenous probes. In vivo microscopy based on vibrational spectroscopic contrast offers a unique approach for visualizing tissue architecture with molecular specificity. We have developed a sensitive technique for vibrational imaging of tissues by combining coherent anti-Stokes Raman scattering (CARS) with video-rate microscopy. Backscattering of the intense forward-propagating CARS radiation in tissue gives rise to a strong epi-CARS signal that makes in vivo imaging possible. This substantially large signal allows for real-time monitoring of dynamic processes, such as the diffusion of chemical compounds, in tissues. By tuning into the CH2 stretching vibrational band, we demonstrate CARS imaging and spectroscopy of lipid-rich tissue structures in the skin of a live mouse, including sebaceous glands, corneocytes, and adipocytes, with unprecedented contrast at subcellular resolution. PMID:16263923

  12. Integrated femtosecond stimulated Raman scattering and two-photon fluorescence imaging of subcellular lipid and vesicular structures.

    PubMed

    Li, Xuesong; Lam, Wen Jiun; Cao, Zhe; Hao, Yan; Sun, Qiqi; He, Sicong; Mak, Ho Yi; Qu, Jianan Y

    2015-11-01

    The primary goal of this study is to demonstrate that stimulated Raman scattering (SRS) as a new imaging modality can be integrated into a femtosecond (fs) nonlinear optical (NLO) microscope system. The fs sources of high pulse peak power are routinely used in multimodal nonlinear microscopy to enable efficient excitation of multiple NLO signals. However, with fs excitations, the SRS imaging of subcellular lipid and vesicular structures encounters significant interference from proteins due to poor spectral resolution and a lack of chemical specificity, respectively. We developed a unique NLO microscope of fs excitation that enables rapid acquisition of SRS and multiple two-photon excited fluorescence (TPEF) signals. In the in vivo imaging of transgenic C. elegans animals, we discovered that by cross-filtering false positive lipid signals based on the TPEF signals from tryptophan-bearing endogenous proteins and lysosome-related organelles, the imaging system produced highly accurate assignment of SRS signals to lipid. Furthermore, we demonstrated that the multimodal NLO microscope system could sequentially image lipid structure/content and organelles, such as mitochondria, lysosomes, and the endoplasmic reticulum, which are intricately linked to lipid metabolism. PMID:26580697

  13. Achromatic miniature lens system for coherent Raman scattering microscopy

    PubMed Central

    Mittal, Richa; Balu, Mihaela; Wilder-Smith, Petra; Potma, Eric O.

    2013-01-01

    We discuss the design and performance of a miniature objective lens optimized for coherent Raman scattering microscopy. The packaged lens assembly has a numerical aperture of 0.51 in water and an outer diameter of 8 mm. The lens system exhibits minimum chromatic aberrations, and produces coherent Raman scattering images with sub-micrometer lateral resolution (0.648 μm) using near-infrared excitation pulses. We demonstrate that despite the small dimensions of the miniature objective, the performance of this lens system is comparable to standard microscope objective lenses, offering opportunities for miniaturizing coherent Raman scattering imaging probes without sacrificing the image quality. PMID:24156075

  14. Resonant Raman Scattering in Antiferromagnets

    NASA Astrophysics Data System (ADS)

    Chubukov, Andrey V.; Morr, Dirk K.

    1996-03-01

    Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-Tc materials. Recent experiments have shown a strong dependence of the Raman signal in B_1g geometry on the frequency of the incoming photon. We present a detailed numerical study of the diagram which was previously identified(A.V. Chubukov and D.M. Frenkel, Phys. Rev. B 52), 9760 (1995) as the most relevant in the resonant regime. We found two maxima of the two-magnon peak hight at transferred frequencies of ω ≈ 3J and ω ≈ 8J. These results agree with recent experiments by Blumberg(G. Blumberg et al.), preprint et al. on Sr_2CuO_2Cl_2. Furthermore, we study how the two-magnon profile depends on a quasiparticle damping and a hopping between next-nearest neighbors. We also study resonance scattering in other scattering geometries, in particular, A_1g scattering.

  15. Resonant Raman scattering in antiferromagnets

    NASA Astrophysics Data System (ADS)

    Morr, Dirk K.; Chubukov, Andrey V.

    1997-10-01

    Two-magnon Raman scattering provides important information about electronic correlations in the insulating parent compounds of high-Tc materials. Recent experiments have shown a strong dependence of the Raman signal in B1g geometry on the frequency of the incoming photon. We present an analytical and numerical study of the Raman intensity in the resonant regime. It has been previously argued by Chubukov and Frenkel that the most relevant contribution to the Raman vertex at resonance is given by the triple resonance diagram. We derive an expression for the Raman intensity in which we simultaneously include the enhancement due to the triple resonance and a final-state interaction. We compute the two-magnon peak height (TMPH) as a function of incident frequency and find two maxima at ω(1)res~2Δ+3J and ω(2)res~2Δ+8J. We argue that the high-frequency maximum is cut only by a quasiparticle damping, while the low-frequency maximum has a finite amplitude even in the absence of damping. We also obtain an evolution of the Raman profile from an asymmetric form around ω(1)res to a symmetric form around ω(2)res. We further show that the TMPH depends on the fermionic quasiparticle damping, the next-nearest-neighbor hopping term t', and the corrections to the interaction vertex between light and the fermionic current. We discuss our results in the context of recent experiments by Blumberg et al. on Sr2CuO2Cl2 and YBa2Cu3O6.1 and Rübhausen et al. on PrBa2Cu3O7 and show that the triple resonance theory yields a qualitative and to some extent also quantitative understanding of the experimental data.

  16. Coherent anti-Stokes Raman scattering microscopy imaging with suppression of four-wave mixing in optical fibers.

    PubMed

    Wang, Zhiyong; Gao, Liang; Luo, Pengfei; Yang, Yaliang; Hammoudi, Ahmad A; Wong, Kelvin K; Wong, Stephen T C

    2011-04-25

    We demonstrated an optical fiber delivered coherent anti-Stokes Raman scattering (CARS) microscopy imaging system with a polarization-based mechanism for suppression of four-wave mixing (FWM) signals in delivery fiber. Polarization maintaining fibers (PMF) were used as the delivery fiber to ensure stability of the state of polarization (SOP) of lasers. The pump and Stokes waves were coupled into PMFs at orthogonal SOPs along the slow and fast axes of PMFs, respectively, resulting in a significant reduction of FWM signals generated in the fiber. At the output end of PMFs, a dual-wavelength waveplate was used to realign the SOPs of the two waves into identical SOPs prior to their entrance into the CARS microscope. Therefore, it allows the pump and Stokes waves with identical SOPs to excite samples at highest excitation efficiency. Our experimental results showed that this polarization-based FWM-suppressing mechanism can dramatically reduce FWM signals generated in PMFs up to approximately 99%. Meanwhile, the PMF-delivered CARS microscopy system with this mechanism can still produce high-quality CARS images. Consequently, our PMF-delivered CARS microscopy imaging system with the polarization-based FWM-suppressing mechanism potentially offers a new strategy for building fiber-based CARS endoscopes with effective suppression of FWM background noises. PMID:21643045

  17. Vibrational imaging of glucose uptake activity in live cells and tissues by stimulated Raman scattering microscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Hu, Fanghao; Chen, Zhixing; Zhang, Luyuan; Shen, Yihui; Wei, Lu; Min, Wei

    2016-03-01

    Glucose is consumed as an energy source by virtually all living organisms, from bacteria to humans. Its uptake activity closely reflects the cellular metabolic status in various pathophysiological transformations, such as diabetes and cancer. Extensive efforts such as positron emission tomography, magnetic resonance imaging and fluorescence microscopy have been made to specifically image glucose uptake activity but all with technical limitations. Here, we report a new platform to visualize glucose uptake activity in live cells and tissues with subcellular resolution and minimal perturbation. A novel glucose analogue with a small alkyne tag (carbon-carbon triple bond) is developed to mimic natural glucose for cellular uptake, which can be imaged with high sensitivity and specificity by targeting the strong and characteristic alkyne vibration on stimulated Raman scattering (SRS) microscope to generate a quantitative three dimensional concentration map. Cancer cells with differing metabolic characteristics can be distinguished. Heterogeneous uptake patterns are observed in tumor xenograft tissues, neuronal culture and mouse brain tissues with clear cell-cell variations. Therefore, by offering the distinct advantage of optical resolution but without the undesirable influence of bulky fluorophores, our method of coupling SRS with alkyne labeled glucose will be an attractive tool to study energy demands of living systems at the single cell level.

  18. Multifunctional superparamagnetic nanoshells: combining two-photon luminescence imaging, surface-enhanced Raman scattering and magnetic separation.

    PubMed

    Jin, Xiulong; Li, Haiyan; Wang, Shanshan; Kong, Ni; Xu, Hong; Fu, Qihua; Gu, Hongchen; Ye, Jian

    2014-11-01

    With the increasing need for multi-purpose analysis in the biomedical field, traditional single diagnosis methods cannot meet the requirements. Therefore new multifunctional technologies and materials for the integration of sample collection, sensing and imaging are in great demand. Core-shell nanoparticles offer a unique platform to combine multifunctions in a single particle. In this work, we have constructed a novel type of core-shell superparamagnetic nanoshell (Fe₃O₄@SiO₂@Au), composed of a Fe₃O₄ cluster core, a thin Au shell and a SiO₂ layer in between. The obtained multifunctional nanoparticles combine the magnetic properties and plasmonic optical properties effectively, which were well investigated by a number of experimental characterization methods and theoretical simulations. We have demonstrated that Fe₃O₄@SiO₂@Au nanoparticles can be utilized for two-photon luminescence (TPL) imaging, near-infrared surface-enhanced Raman scattering (NIR SERS) and cell collection by magnetic separation. The TPL intensity could be further greatly enhanced through the plasmon coupling effect in the self-assembled nanoparticle chains, which were triggered by an external magnetic field. In addition, Fe₃O₄@SiO₂@Au nanoparticles may have great potential applications such as enhanced magnetic resonance imaging (MRI) and photo-thermotherapy. Successful combination of multifunctions including magnetic response, biosensing and bioimaging in single nanoparticles allows further manipulation, real-time tracking, and intracellular molecule analysis of live cells at a single-cell level. PMID:25329447

  19. Assessment of liver steatosis and fibrosis in rats using integrated coherent anti-Stokes Raman scattering and multiphoton imaging technique

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Lu, Fake; Zheng, Wei; Xu, Shuoyu; Tai, Dean; Yu, Hanry; Huang, Zhiwei

    2011-11-01

    We report the implementation of a unique integrated coherent anti-Stokes Raman scattering (CARS), second-harmonic generation (SHG), and two-photon excitation fluorescence (TPEF) microscopy imaging technique developed for label-free monitoring of the progression of liver steatosis and fibrosis generated in a bile duct ligation (BDL) rat model. Among the 21 adult rats used in this study, 18 rats were performed with BDL surgery and sacrificed each week from weeks 1 to 6 (n = 3 per week), respectively; whereas 3 rats as control were sacrificed at week 0. Colocalized imaging of the aggregated hepatic fats, collagen fibrils, and hepatocyte morphologies in liver tissue is realized by using the integrated CARS, SHG, and TPEF technique. The results show that there are significant accumulations of hepatic lipid droplets and collagen fibrils associated with severe hepatocyte necrosis in BDL rat liver as compared to a normal liver tissue. The volume of normal hepatocytes keeps decreasing and the fiber collagen content in BDL rat liver follows a growing trend until week 6; whereas the hepatic fat content reaches a maximum in week 4 and then appears to stop growing in week 6, indicating that liver steatosis and fibrosis induced in a BDL rat liver model may develop at different rates. This work demonstrates that the integrated CARS and multiphoton microscopy imaging technique has the potential to provide an effective means for early diagnosis and detection of liver steatosis and fibrosis without labeling.

  20. Imaging the Effects of Prostaglandin Analogues on Cultured Trabecular Meshwork Cells by Coherent Anti-Stokes Raman Scattering

    PubMed Central

    Lei, Tim C.; Masihzadeh, Omid; Kahook, Malik Y.; Ammar, David A.

    2013-01-01

    Purpose. The aim of this study was to nondestructively monitor morphological changes to the lipid membranes of primary cultures of living human trabecular meshwork cells (hTMC) without the application of exogenous label. Methods. Live hTMC were imaged using two nonlinear optical techniques: coherent anti-Stokes Raman scattering (CARS) and two-photon autofluorescence (TPAF). The hTMC were treated with a commercial formulation of latanoprost (0.5 μg/mL) for 24 hours before imaging. Untreated cells and cells treated with vehicle containing the preservative benzalkonium chloride (BAK; 2 μg/mL) were imaged as controls. After CARS/TPAF imaging, hTMC were fixed, stained with the fluorescent lipid dye Nile Red, and imaged by conventional confocal microscopy to verify lipid membrane structures. Results. Analysis of CARS/TPAF images of hTMC treated with latanoprost revealed multiple intracellular lipid membranes absent from untreated or BAK-treated hTMC. Treatment of hTMC with sodium fluoride or ouabain, agents shown to cause morphological changes to hTMC, also did not induce formation of intracellular lipid membranes. Conclusions. CARS microscopy detected changes in living hTMC morphology that were validated by subsequent histological stain. Prostaglandin-induced changes to hTMC involved rearrangement of lipid membranes within these cells. These in vitro results identify a novel biological response to a class of antiglaucoma drugs, and further experiments are needed to establish how this effect is involved in the hypotensive action of prostaglandin analogues in vivo. PMID:23900606

  1. Expanding multimodal microscopy by high spectral resolution coherent anti-Stokes Raman scattering imaging for clinical disease diagnostics.

    PubMed

    Meyer, Tobias; Chemnitz, Mario; Baumgartl, Martin; Gottschall, Thomas; Pascher, Torbjörn; Matthäus, Christian; Romeike, Bernd F M; Brehm, Bernhard R; Limpert, Jens; Tünnermann, Andreas; Schmitt, Michael; Dietzek, Benjamin; Popp, Jürgen

    2013-07-16

    Over the past years fast label-free nonlinear imaging modalities providing molecular contrast of endogenous disease markers with subcellular spatial resolution have been emerged. However, applications of these imaging modalities in clinical settings are still at the very beginning. This is because single nonlinear imaging modalities such as second-harmonic generation (SHG) and two-photon excited fluorescence (TPEF) have only limited value for diagnosing diseases due to the small number of endogenous markers. Coherent anti-Stokes Raman scattering (CARS) microscopy on the other hand can potentially be added to SHG and TPEF to visualize a much broader range of marker molecules. However, CARS requires a second synchronized laser source and the detection of a certain wavenumber range of the vibrational spectrum to differentiate multiple molecules, which results in increased experimental complexity and often inefficient excitation of SHG and TPEF signals. Here we report the application of a novel near-infrared (NIR) fiber laser of 1 MHz repetition rate, 65 ps pulse duration, and 1 cm(-1) spectral resolution to realize an efficient but experimentally simple SGH/TPEF/multiplex CARS multimodal imaging approach for a label-free characterization of composition of complex tissue samples. This is demonstrated for arterial tissue specimens demonstrating differentiation of elastic fibers, triglycerides, collagen, myelin, cellular cytoplasm, and lipid droplets by analyzing the CARS spectra within the C-H stretching region only. A novel image analysis approach for multispectral CARS data based on colocalization allows correlating spectrally distinct pixels to morphologic structures. Transfer of this highly precise but compact and simple to use imaging approach into clinical settings is expected in the near future. PMID:23781826

  2. Surface enhanced Raman scattering on Tardigrada--towards monitoring and imaging molecular structures in live cryptobiotic organisms.

    PubMed

    Kneipp, Harald; Møbjerg, Nadja; Jørgensen, Aslak; Bohr, Henrik G; Hélix-Nielsen, Claus; Kneipp, Janina; Kneipp, Katrin

    2013-10-01

    Tardigrades are microscopic metazoans which are able to survive extreme physical and chemical conditions by entering a stress tolerant state called cryptobiosis. At present, the molecular mechanisms behind cryptobiosis are still poorly understood. We show that surface enhanced Raman scattering supported by plasmonic gold nanoparticles can measure molecular constituents and their local distribution in live tardigrades. Surface enhanced Raman signatures allow to differentiate between two species and indicate molecular structural differences between tardigrades in water and in a dry state. This opens new avenues for exploring cryptobiosis by studying molecular changes in live cryptobiotic organisms. PMID:23225705

  3. Multifunctional superparamagnetic nanoshells: combining two-photon luminescence imaging, surface-enhanced Raman scattering and magnetic separation

    NASA Astrophysics Data System (ADS)

    Jin, Xiulong; Li, Haiyan; Wang, Shanshan; Kong, Ni; Xu, Hong; Fu, Qihua; Gu, Hongchen; Ye, Jian

    2014-11-01

    With the increasing need for multi-purpose analysis in the biomedical field, traditional single diagnosis methods cannot meet the requirements. Therefore new multifunctional technologies and materials for the integration of sample collection, sensing and imaging are in great demand. Core-shell nanoparticles offer a unique platform to combine multifunctions in a single particle. In this work, we have constructed a novel type of core-shell superparamagnetic nanoshell (Fe3O4@SiO2@Au), composed of a Fe3O4 cluster core, a thin Au shell and a SiO2 layer in between. The obtained multifunctional nanoparticles combine the magnetic properties and plasmonic optical properties effectively, which were well investigated by a number of experimental characterization methods and theoretical simulations. We have demonstrated that Fe3O4@SiO2@Au nanoparticles can be utilized for two-photon luminescence (TPL) imaging, near-infrared surface-enhanced Raman scattering (NIR SERS) and cell collection by magnetic separation. The TPL intensity could be further greatly enhanced through the plasmon coupling effect in the self-assembled nanoparticle chains, which were triggered by an external magnetic field. In addition, Fe3O4@SiO2@Au nanoparticles may have great potential applications such as enhanced magnetic resonance imaging (MRI) and photo-thermotherapy. Successful combination of multifunctions including magnetic response, biosensing and bioimaging in single nanoparticles allows further manipulation, real-time tracking, and intracellular molecule analysis of live cells at a single-cell level.With the increasing need for multi-purpose analysis in the biomedical field, traditional single diagnosis methods cannot meet the requirements. Therefore new multifunctional technologies and materials for the integration of sample collection, sensing and imaging are in great demand. Core-shell nanoparticles offer a unique platform to combine multifunctions in a single particle. In this work, we have

  4. Imaging the intracellular distribution of tyrosine kinase inhibitors in living cells with quantitative hyperspectral stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Fu, Dan; Zhou, Jing; Zhu, Wenjing Suzanne; Manley, Paul W.; Wang, Y. Karen; Hood, Tami; Wylie, Andrew; Xie, X. Sunney

    2014-07-01

    ABL1 tyrosine-kinase inhibitors (TKI) are front-line therapy for chronic myelogenous leukaemia and are among the best-known examples of targeted cancer therapeutics. However, the dynamic uptake into cells of TKIs of low molecular weight and their intracellular behaviour is unknown because of the difficulty of observing non-fluorescent small molecules at subcellular resolution. Here we report the direct label-free visualization and quantification of two TKI drugs (imatinib and nilotinib) inside living cells using hyperspectral stimulated Raman scattering imaging. Concentrations of both drugs were enriched over 1,000-fold in lysosomes as a result of their lysosomotropic properties. In addition, low solubility appeared to contribute significantly to the surprisingly large accumulation of nilotinib. We further show that the lysosomal trapping of imatinib was reduced more than tenfold when chloroquine is used simultaneously, which suggests that chloroquine may increase the efficacy of TKIs through lysosome-mediated drug-drug interaction in addition to the commonly proposed autophagy-inhibition mechanism.

  5. Stimulated Raman scattering in large plasmas

    SciTech Connect

    Phillion, D.W.; Banner, D.L.

    1980-11-06

    Stimulated Raman scattering is of concern to laser fusion since it can create a hot electron environment which can increase the difficulty of achieving high final fuel densities. In earlier experiments with one micron laser light, the energy measured in Raman-scattered light has been insignificant. But these experiments were done with, at most, about 100 joules of laser energy. The Raman instability has a high threshold which also requires a large plasma to be irradiated with a large diameter spot. Only with a long interaction length can the Raman-scattered light wave convectively grow to a large amplitude, and only in recent long pulse, high energy experiments (4000 joules in 2 ns) at the Shiva laser facility have we observed as much as several percent of the laser light to be Raman-scattered. We find that the Raman instability has a much lower intensity threshold for longer laser pulselength and larger laser spot size on a solid target.

  6. Filter-based method for background removal in high-sensitivity wide-field-surface-enhanced Raman scattering imaging in vivo.

    PubMed

    Mallia, Rupananda J; McVeigh, Patrick Z; Veilleux, Israel; Wilson, Brian C

    2012-07-01

    As molecular imaging moves towards lower detection limits, the elimination of endogenous background signals becomes imperative. We present a facile background-suppression technique that specifically segregates the signal from surface-enhanced Raman scattering (SERS)-active nanoparticles (NPs) from the tissue autofluorescence background in vivo. SERS NPs have extremely narrow spectral peaks that do not overlap significantly with endogenous Raman signals. This can be exploited, using specific narrow-band filters, to image picomolar (pM) concentrations of NPs against a broad tissue autofluorescence background in wide-field mode, with short integration times that compare favorably with point-by-point mapping typically used in SERS imaging. This advance will facilitate the potential applications of SERS NPs as contrast agents in wide-field multiplexed biomarker-targeted imaging in vivo. PMID:22894500

  7. Imaging growth of neurites in conditioned hydrogel by coherent anti-stokes raman scattering microscopy.

    PubMed

    Conovaloff, Aaron; Wang, Han-Wei; Cheng, Ji-Xin; Panitch, Alyssa

    2009-10-01

    Cultured DRGs in different gel scaffolds were analyzed using CA RS microscopy to determine its possible use as a label-free imaging option for tracking cellular growth in a gel scaffold. This study demonstrates for the first time the applicability of CA RS microscopy to the imaging of live neuronal cells in GAG hydrogels. By tuning the laser beating frequency, omega(p)-omega(s), to match the vibration of C-H bonds in the cell membrane, the CA RS signal yields detailed, high-quality images of neurites with single membrane detection sensitivity. The results demonstrate that CA RS imaging allows monitoring of cellular growth in a tissue scaffold over time, with a contrast that shows comparable cellular structures to those obtained using standard fluorescent staining techniques. These findings show the potential of CARS microscopy to assist in the understanding of organogenesis processes in a tissue scaffold. PMID:20539743

  8. Coherent Anti-Stokes Raman Scattering Microscopy: A Biological Review

    SciTech Connect

    Rodriguez, Luis; Lockett, Stephen J.; Holtom, Gary R.

    2006-08-31

    Microscopic imaging of cells and tissues are generated by the interaction of light with either the sample itself or contrast agents that label the sample. Most contrast agents, however, alter the cell in order to introduce molecular labels, complicating live cell imaging. The interaction of light from multiple laser sources has given rise to microscopy, based on Raman scattering or vibrational resonance, which demonstrates selectivity to specific chemical bonds while cell imaging unmodified live cells. Here, we discuss the nonlinear optical technique of coherent anti-Stokes Raman scattering (CARS) microscopy, its instrumentation, and its status in live cell imaging.

  9. An integrated coherent anti-Stokes Raman scattering and multiphoton imaging technique for liver disease diagnosis

    NASA Astrophysics Data System (ADS)

    Lin, Jian; Lu, Fake; Zheng, Wei; Yu, Hanry; Sheppard, Colin; Huang, Zhiwei

    2012-03-01

    Liver steatosis and fibrosis are two prevalence liver diseases and may eventually develop into hepatocellular carcinoma (HCC) Due to their prevalence and severity, much work has been done to develop efficient diagnostic methods and therapies. Nonlinear optical microscopy has high sensitivity and chemical specificity for major biochemical compounds, making it a powerful tool for tissue imaging without staining. In this study, three nonlinear microscopy imaging modalities are applied to the study of liver diseases in a bile duct ligation rat modal. CARS shows the distributions of fats or lipids quantitatively across the tissue; SHG visualizes the collagens; and TPEF reveals the morphology of hepatic cells. The results clearly show the development of liver steatosis and fibrosis with time, and the hepatic fat and collagen fibrils are quantified. This study demonstrates the ability of multimodal nonlinear optical microscopy for liver disease diagnosis, and may provide new insights into the understanding of the mechanisms of steatosis/fibrosis transformations at the cellular and molecular levels.

  10. Label-free real-time imaging of myelination in the Xenopus laevis tadpole by in vivo stimulated Raman scattering microscopy

    PubMed Central

    Hu, Chun-Rui; Zhang, Delong; Slipchenko, Mikhail N.; Cheng, Ji-Xin; Hu, Bing

    2014-01-01

    Abstract. The myelin sheath plays an important role as the axon in the functioning of the neural system, and myelin degradation is a hallmark pathology of multiple sclerosis and spinal cord injury. Electron microscopy, fluorescent microscopy, and magnetic resonance imaging are three major techniques used for myelin visualization. However, microscopic observation of myelin in living organisms remains a challenge. Using a newly developed stimulated Raman scattering microscopy approach, we report noninvasive, label-free, real-time in vivo imaging of myelination by a single-Schwann cell, maturation of a single node of Ranvier, and myelin degradation in the transparent body of the Xenopus laevis tadpole. PMID:25104411

  11. Label-free real-time imaging of myelination in the Xenopus laevis tadpole by in vivo stimulated Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

    Hu, Chun-Rui; Zhang, Delong; Slipchenko, Mikhail N.; Cheng, Ji-Xin; Hu, Bing

    2014-08-01

    The myelin sheath plays an important role as the axon in the functioning of the neural system, and myelin degradation is a hallmark pathology of multiple sclerosis and spinal cord injury. Electron microscopy, fluorescent microscopy, and magnetic resonance imaging are three major techniques used for myelin visualization. However, microscopic observation of myelin in living organisms remains a challenge. Using a newly developed stimulated Raman scattering microscopy approach, we report noninvasive, label-free, real-time in vivo imaging of myelination by a single-Schwann cell, maturation of a single node of Ranvier, and myelin degradation in the transparent body of the Xenopus laevis tadpole.

  12. Super-Spatial- and -Spectral-Resolution in Vibrational Imaging via Saturated Coherent Anti-Stokes Raman Scattering

    NASA Astrophysics Data System (ADS)

    Yonemaru, Yasuo; Palonpon, Almar F.; Kawano, Shogo; Smith, Nicholas I.; Kawata, Satoshi; Fujita, Katsumasa

    2015-07-01

    We demonstrate a vibrational microscopy technique with subdiffraction spatial resolution by the use of saturation of coherent anti-Stokes Raman scattering (CARS). The saturated CARS signals effectively produce a reduced point-spread function at harmonic frequencies, which is extracted by temporal modulation of the pump beam and demodulation of the CARS signal. An increase in spectral resolution and suppression of the nonresonant background signal accompany the spatial- resolution enhancement. Our simple, enhanced CARS technique promises to be useful in studying molecules in gas and liquid phases as well as soft condensed-matter systems.

  13. Resonant Raman scattering in nanoscale pentacene films

    NASA Astrophysics Data System (ADS)

    He, Rui; Dujovne, Irene; Chen, Liwei; Miao, Qian; Hirjibehedin, Cyrus F.; Pinczuk, Aron; Nuckolls, Colin; Kloc, Christian; Ron, Arza

    2004-02-01

    Resonant Raman scattering intensities from nanoscale films of pentacene display large resonant enhancements that enable observation of vibrational modes in monolayer cluster films. The resonant enhancements occur when the outgoing photon energy overlaps the free exciton optical transitions observed in luminescence. The results point to the significant potential of resonant Raman methods in the characterization of nanoscale structures of organic molecular semiconductors.

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

    NASA Astrophysics Data System (ADS)

    Lempert, Walter R.; Adamovich, Igor V.

    2014-10-01

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

  15. Aggregation induced Raman scattering of squaraine dye: Implementation in diagnosis of cervical cancer dysplasia by SERS imaging.

    PubMed

    Narayanan, Nisha; Karunakaran, Varsha; Paul, Willi; Venugopal, Karunakaran; Sujathan, K; Kumar Maiti, Kaustabh

    2015-08-15

    The extent of squaraine dye aggregation that reflects on surface enhanced Raman signal scattering (SERS) intensity upon adsorption on nano-roughened gold surface has been investigated. Here we have synthesized a serious of six squaraine dyes consisting of two different electron donor moiety i.e. 1,1,2-trimethyl-1H-benzo[e]indole and 2-methylbenzo[d]thiazole which modulates the chemisorptions and hydrophobicity being designated as SQ1, SQ2, SQ3, SQ4, SQ5 and SQ6. Interestingly, SQ2 (mono lipoic acid appended), SQ5 and SQ6 (conjugated with hexyl and dodecyl side chain) squaraine derivatives having more tendency of aggregation in DMSO-water mixed solvent showed significant increase of Raman scattering in the fingerprint region when chemisorbed on spherical gold nanoparticles. Two sets of SERS nanotags were prepared with colloidal gold nanoparticle (Au-NPs size: 40 nm) by incorporating Raman reporters SQ2 and SQ5 followed by thiolated PEG encapsulation (SH-PEG, SH-PEG-COOH) denoted as AuNPs-SQ2-PEG and AuNPs-SQ5-PEG. Further conjugation of these nanotag with monoclonal antibodies specific to over expressed receptors, EGFR and p16/Ki-67 in cervical cancer cell, HeLa showed prominent SERS mapping intensity and selectivity towards cell surface and nucleus. The fast and accurate recognition obtained by antibody triggered SERS-nanotag has been compared with conventional time consuming immunocytochemistry technique which prompted us to extend further investigation using real patient cervical smear sample for a non-invasive, ultrafast and accurate diagnosis. PMID:25801955

  16. Aerosol particle analysis by Raman scattering technique

    SciTech Connect

    Fung, K.H.; Tang, I.N.

    1992-10-01

    Laser Raman spectroscopy is a very versatile tool for chemical characterization of micron-sized particles. Such particles are abundant in nature, and in numerous energy-related processes. In order to elucidate the formation mechanisms and understand the subsequent chemical transformation under a variety of reaction conditions, it is imperative to develop analytical measurement techniques for in situ monitoring of these suspended particles. In this report, we outline our recent work on spontaneous Raman, resonance Raman and non-linear Raman scattering as a novel technique for chemical analysis of aerosol particles as well as supersaturated solution droplets.

  17. Highly selective standoff detection and imaging of trace chemicals in a complex background using single-beam coherent anti-Stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Bremer, Marshall T.; Wrzesinski, Paul J.; Butcher, Nathan; Lozovoy, Vadim V.; Dantus, Marcos

    2011-09-01

    A non-destructive and highly selective method of standoff detection is presented and quantitatively evaluated. The method is found to be orders of magnitude more sensitive than previous coherent spectroscopy methods, identifying concentrations as low as 2 μg/cm2 of an explosive simulant mixed in a polymer matrix. The approach uses a single amplified femtosecond laser to generate high-resolution multiplex coherent anti-Stokes Raman scattering (CARS) spectra encompassing the fingerprint region (400-2500 cm-1) at standoff distance. Additionally, a standoff imaging modality is introduced, visually demonstrating similar sensitivity and high selectivity, providing promising results toward highly selective trace detection of explosives or warfare agents.

  18. Hyperspectral imaging and characterization of live cells by broadband coherent anti-Stokes Raman scattering (CARS) microscopy with singular value decomposition (SVD) analysis.

    PubMed

    Khmaladze, Alexander; Jasensky, Joshua; Price, Erika; Zhang, Chi; Boughton, Andrew; Han, Xiaofeng; Seeley, Emily; Liu, Xinran; Banaszak Holl, Mark M; Chen, Zhan

    2014-01-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy can be used as a powerful imaging technique to identify chemical compositions of complex samples in biology, biophysics, medicine, and materials science. In this work we developed a CARS microscopic system capable of hyperspectral imaging. By employing an ultrafast laser source, a photonic crystal fiber, and a scanning laser microscope together with spectral detection by a highly sensitive back-illuminated cooled charge-coupled device (CCD) camera, we were able to rapidly acquire and process hyperspectral images of live cells with chemical selectivity. We discuss various aspects of hyperspectral CARS image analysis and demonstrate the use of singular value decomposition methods to characterize the cellular lipid content. PMID:25198903

  19. Surface-Enhanced Raman Scattering and Biophysics

    NASA Astrophysics Data System (ADS)

    Kneipp, Katrin

    2001-03-01

    Surface-enhanced Raman scattering (SERS) is a phenomenon resulting in strongly increased Raman signals from molecules which have been attached to metallic nanostructures such as colloidal silver or gold particles. The effect combines the structural information content of a vibrational spectroscopy with extremely high sensitivity and in some cases, it showes promise in overcoming the low-sensitivity problems inherent in Raman spectroscopy. Cross sections effective in SERS can reach 10 16 to 10 15 cm2 per molecule corresponding to enhancement factors of about fourteen orders of magnitude compared with “normal” non-resonant Raman scattering. Such extremely large cross sections are sufficient for single molecule Raman spectroscopy. The high sensitivity and particularly the single molecule capabilities open up exciting perspectives for SERS as tool for basic research in biophysics, biochemistry and in laboratory medicine, where it allows to study extremely small amounts of biolomedically relevant molecules in order to understand development of diseases, treatment and therapy control based on molecular structural information at the single molecule level. The most spectacular applications might appear in rapidly spectroscopic characterization of specific DNA fragments down to structurally sensitive detection of single bases in order to elucidate the human genome sequence without any labeling technology. I will briefly introduce the SERS effect and report experiments with Raman scattering of single molecules. Potential and limitations of surface-enhanced Raman techniques as a tool in biophysics and biomedical spectroscopy will be considered.

  20. Random number generation from spontaneous Raman scattering

    NASA Astrophysics Data System (ADS)

    Collins, M. J.; Clark, A. S.; Xiong, C.; Mägi, E.; Steel, M. J.; Eggleton, B. J.

    2015-10-01

    We investigate the generation of random numbers via the quantum process of spontaneous Raman scattering. Spontaneous Raman photons are produced by illuminating a highly nonlinear chalcogenide glass ( As 2 S 3 ) fiber with a CW laser at a power well below the stimulated Raman threshold. Single Raman photons are collected and separated into two discrete wavelength detuning bins of equal scattering probability. The sequence of photon detection clicks is converted into a random bit stream. Postprocessing is applied to remove detector bias, resulting in a final bit rate of ˜650 kb/s. The collected random bit-sequences pass the NIST statistical test suite for one hundred 1 Mb samples, with the significance level set to α = 0.01 . The fiber is stable, robust and the high nonlinearity (compared to silica) allows for a short fiber length and low pump power favourable for real world application.

  1. Optical tomography in reacting flows based on Stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Sharaborin, D.; Chikishev, L.; Dulin, V.

    2015-11-01

    This paper reports on development of an optical system for tomographic imaging in reacting flows. The measurement principle is based on registration of Stokes Raman scattering (rovibrational transitions for molecular nitrogen), when a transparent object is illuminated by a laser sheet. The method allows to retrieve local gas density and concentration.

  2. Wavefront shaping enhanced Raman scattering in a turbid medium.

    PubMed

    Thompson, Jonathan V; Throckmorton, Graham A; Hokr, Brett H; Yakovlev, Vladislav V

    2016-04-15

    Spontaneous Raman scattering is a powerful tool for chemical sensing and imaging but suffers from a weak signal. In this Letter, we present an application of adaptive optics to enhance the Raman scattering signal detected through a turbid, optically thick material. This technique utilizes recent advances in wavefront shaping techniques for focusing light through a turbid media and applies them to chemical detection to achieve a signal enhancement with little sacrifice to the overall simplicity of the experimental setup. With this technique, we demonstrate an enhancement in the Raman signal from titanium dioxide particles through a highly scattering material. This technique may pave the way to label-free tracking using the optical memory effect. PMID:27082341

  3. Temperature dependence of sapphire fiber Raman scattering

    DOE PAGESBeta

    Liu, Bo; Yu, Zhihao; Tian, Zhipeng; Homa, Daniel; Hill, Cary; Wang, Anbo; Pickrell, Gary

    2015-04-27

    Anti-Stokes Raman scattering in sapphire fiber has been observed for the first time. Temperature dependence of Raman peaks’ intensity, frequency shift, and linewidth were also measured. Three anti-Stokes Raman peaks were observed at temperatures higher than 300°C in a 0.72-m-long sapphire fiber excited by a second-harmonic Nd YAG laser. The intensity of anti-Stokes peaks are comparable to that of Stokes peaks when the temperature increases to 1033°C. We foresee the combination of sapphire fiber Stokes and anti-Stokes measurement in use as a mechanism for ultrahigh temperature sensing.

  4. Raman scattering studies of pollutant systems.

    NASA Technical Reports Server (NTRS)

    Schwiesow, R. L.

    1971-01-01

    Results and techniques for laboratory measurements of Raman scattering cross sections and depolarization ratios of atmospheric gases as a function of the incident photon energy are discussed. Referred to N2, the cross section of H2O changes by a factor of 2 as the incident photon energy is changed by 5%. Less striking results are obtained for SO2, NO and other atmospheric gases. Tentative results are given for spectral features of scattering from polluted air-water interfaces. Raman lidar is assessed as a potentially useful aid in remote sensing of atmospheric and water-borne pollution distributions at least in near-source concentrations.

  5. Fiber bundle based endomicroscopy prototype with two collection channels for simultaneous coherent anti-Stokes Raman scattering and second harmonic generation imaging

    NASA Astrophysics Data System (ADS)

    Liu, Zhengfan; Satira, Zachary A.; Wang, Xi; Xu, Xiaoyun; Chen, Xu; Wong, Kelvin; Chen, Shufen; Xin, Jianguo; Wong, Stephen T. C.

    2014-02-01

    Label-free multiphoton imaging is promising for replacing biopsy and could offer new strategies for intraoperative or surgical applications. Coherent anti-Stokes Raman scattering (CARS) imaging could provide lipid-band contrast, and second harmonic generation (SHG) imaging is useful for imaging collagen, tendon and muscle fibers. A combination of these two imaging modalities could provide rich information and this combination has been studied by researchers to investigate diseases through microscopy imaging. The combination of these two imaging modalities in endomicroscopy imaging has been rarely investigated. In this research, a fiber bundle consisted of one excitation fiber and 18 collection fibers was developed in our endomicroscopy prototype. The 18 collection fibers were divided into two collection channels with 9 fibers in each channel. These two channels could be used together as one channel for effective signal collection or used separately for simplifying detection part of the system. Differences of collection pattern of these two channels were investigated. Collection difference of central excitation fiber and surrounding 18 fibers was also investigated, which reveals the potential ability of this system to measure forward to backward (F/B) ratio in SHG imaging. CARS imaging of mouse adipocyte and SHG imaging of mouse tail tendon were performed to demonstrate the CARS and SHG tissue imaging performance of this system. Simultaneous CARS and SHG imaging ability of this system was demonstrated by mouse tail imaging. This fiber bundle based endomicroscopy imaging prototype, offers a promising platform for constructing efficient fiber-based CARS and SHG multimodal endomicroscopes for label free intraoperative imaging applications.

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

    SciTech Connect

    Meyer, Matthew W.

    2013-01-01

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

  7. Integrated Raman and angular scattering of single biological cells

    NASA Astrophysics Data System (ADS)

    Smith, Zachary J.

    2009-12-01

    Raman, or inelastic, scattering and angle-resolved elastic scattering are two optical processes that have found wide use in the study of biological systems. Raman scattering quantitatively reports on the chemical composition of a sample by probing molecular vibrations, while elastic scattering reports on the morphology of a sample by detecting structure-induced coherent interference between incident and scattered light. We present the construction of a multimodal microscope platform capable of gathering both elastically and inelastically scattered light from a 38 mum2 region in both epi- and trans-illumination geometries. Simultaneous monitoring of elastic and inelastic scattering from a microscopic region allows noninvasive characterization of a living sample without the need for exogenous dyes or labels. A sample is illuminated either from above or below with a focused 785 nm TEM00 mode laser beam, with elastic and inelastic scattering collected by two separate measurement arms. The measurements may be made either simultaneously, if identical illumination geometries are used, or sequentially, if the two modalities utilize opposing illumination paths. In the inelastic arm, Stokes-shifted light is dispersed by a spectrograph onto a CCD array. In the elastic scattering collection arm, a relay system images the microscope's back aperture onto a CCD detector array to yield an angle-resolved elastic scattering pattern. Post-processing of the inelastic scattering to remove fluorescence signals yields high quality Raman spectra that report on the sample's chemical makeup. Comparison of the elastically scattered pupil images to generalized Lorenz-Mie theory yields estimated size distributions of scatterers within the sample. In this thesis we will present validations of the IRAM instrument through measurements performed on single beads of a few microns in size, as well as on ensembles of sub-micron particles of known size distributions. The benefits and drawbacks of the

  8. Label-free surface-enhanced Raman scattering imaging to monitor the metabolism of antitumor drug 6-mercaptopurine in living cells.

    PubMed

    Han, Guangmei; Liu, Renyong; Han, Ming-Yong; Jiang, Changlong; Wang, Jianping; Du, Shuhu; Liu, Bianhua; Zhang, Zhongping

    2014-12-01

    The molecular processes of drugs from cellular uptake to intracellular distribution as well as the intracellular interaction with the target molecule are critically important for the development of new antitumor drugs. In this work, we have successfully developed a label-free surface-enhanced Raman scattering (SERS) technique to monitor and visualize the metabolism of antitumor drug 6-mercaptopurine in living cells. It has been clearly demonstrated that Au@Ag NPs exhibit an excellent Raman enhancement effect to both 6-mercaptopurine and its metabolic product 6-mercaptopurine-ribose. Their different ways to absorb at the surface of Au@Ag NPs lead to the obvious spectral difference for distinguishing the antitumor drug and its metabolite by SERS spectra. The Au@Ag NPs can easily pass through cell membranes in a large amount and sensitively respond to the biological conversion of 6-mercaptopurine in tumor cells. The Raman imaging can visualize the real-time distribution of 6-mercaptopurine and its biotransformation with the concentrations in tumor cells. The SERS-based method reported here is simple and efficient for the assessments of drug efficacy and the understanding of the molecular therapeutic mechanism of antitumor drugs at the cellular level. PMID:25372629

  9. Nonlinear kinetic modeling of stimulated Raman scattering

    NASA Astrophysics Data System (ADS)

    Benisti, Didier

    2011-10-01

    Despite its importance for many applications, such as or Raman amplification or inertial confinement fusion, deriving a nonlinear estimate of Raman reflectivity in a plasma has remained quite a challenge for decades. This is mainly due to the nonlinear modification of the electron distribution function induced by the plasma wave (EPW), which, in turn, modifies the propagation of this wave. In this paper is derived an envelope equation for the EPW valid in 3D and which accounts for the nonlinear change of its collisionless (Landau-like) damping rate, group velocity, coupling to the electromagnetic drive, frequency and wave number. Our theoretical predictions for each of these terms are carefully compared against results from Vlasov simulations of stimulated Raman scattering (SRS), as well as with other theories. Moreover, our envelope model shows to be as accurate as a Vlasov code in predicting Raman threshold in 1D. Making comparisons with experimental results nevertheless requires including transverse dimensions and letting Raman start from noise. To this end, we performed a completely new derivation of the electrostatic fluctuations in a plasma, which accounts nonlinear effects. Moreover, based on our Multi-D simulations of Raman scattering with our envelope code BRAMA, we discuss the effect on SRS of wave front bowing, transverse detrapping and of a completely new defocussing effect due to the local change in the direction of the EPW group velocity induced by the nonlinear decrease of Landau damping.

  10. Raman and coherent anti-Stokes Raman scattering microspectroscopy for biomedical applications.

    PubMed

    Krafft, Christoph; Dietzek, Benjamin; Schmitt, Michael; Popp, Jürgen

    2012-04-01

    A tutorial article is presented for the use of linear and nonlinear Raman microspectroscopies in biomedical diagnostics. Coherent anti-Stokes Raman scattering (CARS) is the most frequently applied nonlinear variant of Raman spectroscopy. The basic concepts of Raman and CARS are introduced first, and subsequent biomedical applications of Raman and CARS are described. Raman microspectroscopy is applied to both in-vivo and in-vitro tissue diagnostics, and the characterization and identification of individual mammalian cells. These applications benefit from the fact that Raman spectra provide specific information on the chemical composition and molecular structure in a label-free and nondestructive manner. Combining the chemical specificity of Raman spectroscopy with the spatial resolution of an optical microscope allows recording hyperspectral images with molecular contrast. We also elaborate on interfacing Raman spectroscopic tools with other technologies such as optical tweezing, microfluidics and fiber optic probes. Thereby, we aim at presenting a guide into one exciting branch of modern biophotonics research. PMID:22559673

  11. Transparent material thickness measurements by Raman scattering.

    PubMed

    Pershin, Sergey M; Lednev, Vasily N; Yulmetov, Renat N; Klinkov, Vladimir K; Bunkin, Alexey F

    2015-07-01

    An efficient and simple and convenient technique for transparent samples thickness measurements by Raman spectroscopy is suggested. The elastic scattering can be effectively used for sample border indication if the refractive index changes more than 3%, while it fails to detect an ice-to-water border of floating ice. The alternative is to use Raman spectroscopy to detect the interface between different layers of transparent materials. The difference between the Raman spectra of poly methyl methacrylate (PMMA) and water, and between ice and liquid water were employed to locate the PMMA-water and ice-water interfaces, while elastic scattering was used for air-solid surface detection. This approach yields an error of 2%-5% indicating that it is promising to express a remote and noninvasive thickness measurement technique in field experiments. PMID:26193136

  12. Hydrazine Detectors Based On Raman Scattering

    NASA Technical Reports Server (NTRS)

    Rupich, Martin W.; Carrabba, Michael M.

    1992-01-01

    Goal of sensor-development program to measure concentrations as low as few parts per billion in continuous monitoring as well as peak concentrations up to hundreds of parts per million, such as encountered near leaks. Sensors based on Raman scattering from hydrazine or monomethyl hydrazine adsorbed on roughened metal or metal oxide substrates. Similar systems developed to detect nitrogen oxides and other gases.

  13. Stimulated Electronic X-Ray Raman Scattering

    NASA Astrophysics Data System (ADS)

    Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A.; Bozek, John D.; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J.; Rohringer, Nina

    2013-12-01

    We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state.

  14. Observation of Raman scattering by cloud droplets in the atmosphere.

    PubMed

    Melfi, S H; Evans, K D; Li, J; Whiteman, D; Ferrare, R; Schwemmer, G

    1997-05-20

    In a recent field campaign, the NASA Goddard Space Flight Center scanning Raman lidar measured, in the water vapor channel, Raman scattering from low-level clouds well in excess of 100% relative humidity. The excess scattering has been interpreted to be spontaneous Raman scattering by liquid water in the cloud droplets. A review of research on Raman scattering by microspheres indicates that the technique may provide a remote method to observe cloud liquid water. The clouds studied appear, from Mie scattering, to have two distinct layers with only the upper layer showing significant Raman scattering from liquid water in the droplets. PMID:18253375

  15. In planta imaging of Δ9-tetrahydrocannabinolic acid in Cannabis sativa L. with hyperspectral coherent anti-Stokes Raman scattering microscopy

    NASA Astrophysics Data System (ADS)

    Garbacik, Erik T.; Korai, Roza P.; Frater, Eric H.; Korterik, Jeroen P.; Otto, Cees; Offerhaus, Herman L.

    2013-04-01

    Nature has developed many pathways to produce medicinal products of extraordinary potency and specificity with significantly higher efficiencies than current synthetic methods can achieve. Identification of these mechanisms and their precise locations within plants could substantially increase the yield of a number of natural pharmaceutics. We report label-free imaging of Δ9-tetrahydrocannabinolic acid (THCa) in Cannabis sativa L. using coherent anti-Stokes Raman scattering microscopy. In line with previous observations we find high concentrations of THCa in pistillate flowering bodies and relatively low amounts within flowering bracts. Surprisingly, we find differences in the local morphologies of the THCa-containing bodies: organelles within bracts are large, diffuse, and spheroidal, whereas in pistillate flowers they are generally compact, dense, and have heterogeneous structures. We have also identified two distinct vibrational signatures associated with THCa, both in pure crystalline form and within Cannabis plants; at present the exact natures of these spectra remain an open question.

  16. Raman scattering in the atmospheres of the major planets

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

    A technique is developed to calculate the detailed effects of Raman scattering in an inhomogeneous anisotropically scattering atmosphere. The technique is applied to evaluations of Raman scattering by H2 in the atmosphere of the major planets. It is noted that Raman scattering produces an insufficient decrease in the blue and ultraviolet regions to explain the albedos of all planets investigated. For all major planets, the filling-in of solar line cores and the generation of the Raman-shifted ghosts of the Fraunhofer spectrum are observed. With regard to Uranus and Neptune, Raman scattering is seen to exert a major influence on the formation and profile of strong red and near infrared CH4 bands, and Raman scattering by H2 explains the residual intensity in the cores of these bands. Raman scattering by H2 must also be taken into account in the scattering of photons into the cores of saturated absorption bands.

  17. Raman Reporter-Coupled Ag(core)@Au(shell) Nanostars for in Vivo Improved Surface Enhanced Raman Scattering Imaging and Near-infrared-Triggered Photothermal Therapy in Breast Cancers.

    PubMed

    Zeng, Leyong; Pan, Yuanwei; Wang, Shouju; Wang, Xin; Zhao, Xinmei; Ren, Wenzhi; Lu, Guangming; Wu, Aiguo

    2015-08-01

    Noble-metal nanomaterials were widely investigated as theranostic systems for surface enhanced Raman scattering (SERS) imaging, and also for photothermal therapy (PTT) of cancers. However, it was still a major challenge to explore multifunctional nanoprobes with high performance, high stability, and low toxicity. In this work, Raman reporter (DTTC)-coupled Agcore@Aushell nanostars (Ag@Au-DTTC) were synthesized and investigated for in vivo improved SERS imaging and near-infrared (NIR)-triggered PTT of breast cancers. By the two-step coupling of DTTC, the SERS signal was improved obviously, and the cytotoxicity of nanoparticles was also decreased by coating Au nanostars onto Ag nanoparticles. The as-prepared Ag@Au-DTTC nanostars showed high photostability and excellent photothermal performance, in which the photothermal conversion efficiency was up to 79.01% under the irradiation of an 808 nm laser. The in vitro and in vivo SERS measurements of Ag@Au-DTTC nanostars showed that the many sharp and narrow Raman peaks located at 508, 782, 844, 1135, 1242, 1331, 1464, 1510, and 1580 cm(-1) could be obviously observed in MCF-7 cells and in MCF-7 tumor-bearing nude mice, compared with that in pure DTTC. In 14-day treatments, the tumor volume of MCF-7 tumor-bearing nude mice injected with Ag@Au-DTTC nanostars and irradiated by an 808 nm laser almost disappeared. This study demonstrated that the as-prepared Ag@Au-DTTC nanostars could be excellent multifunctional agents for improved SERS imaging and NIR-triggered PTT of breast cancers with low risk. PMID:26204589

  18. RAMAN MICROSPECTROSCOPY AND IMAGING

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although the Raman effect was discovered in 1928 by C.V. Raman it received little attention as a spectroscopic method until lasers (high intensity monochromatic light sources) were employed as sources. Recent developments to include improved detectors and filters, techniques to suppress of fluoresc...

  19. Coherent Raman Scattering Microscopy in Biology and Medicine

    PubMed Central

    Zhang, Chi; Zhang, Delong; Cheng, Ji-Xin

    2016-01-01

    Advancements in coherent Raman scattering (CRS) microscopy have enabled label-free visualization and analysis of functional, endogenous biomolecules in living systems. When compared with spontaneous Raman microscopy, a key advantage of CRS microscopy is the dramatic improvement in imaging speed, which gives rise to real-time vibrational imaging of live biological samples. Using molecular vibrational signatures, recently developed hyperspectral CRS microscopy has improved the readout of chemical information available from CRS images. In this article, we review recent achievements in CRS microscopy, focusing on the theory of the CRS signal-to-noise ratio, imaging speed, technical developments, and applications of CRS imaging in bioscience and clinical settings. In addition, we present possible future directions that the use of this technology may take. PMID:26514285

  20. Raman Scattering in Carbon Nanosystems: Solving Polyacetylene

    PubMed Central

    2015-01-01

    Polyacetylene has been a paradigm conjugated organic conductor since well before other conjugated carbon systems such as nanotubes and graphene became front and center. It is widely acknowledged that Raman spectroscopy of these systems is extremely important to characterize them and understand their internal quantum behavior. Here we show, for the first time, what information the Raman spectrum of polyacetylene contains, by solving the 35-year-old mystery of its spectrum. Our methods have immediate and clear implications for other conjugated carbon systems. By relaxing the nearly universal approximation of ignoring the nuclear coordinate dependence of the transition moment (Condon approximation), we find the reasons for its unusual spectroscopic features. When the Kramers–Heisenberg–Dirac Raman scattering theory is fully applied, incorporating this nuclear coordinate dependence, and also the energy and momentum dependence of the electronic and phonon band structure, then unusual line shapes, growth, and dispersion of the bands are explained and very well matched by theory. PMID:27162945

  1. Coherent anti-Stokes Raman scattering microscope with a high-signal-to-noise ratio, high stability, and high-speed imaging for live cell observation

    NASA Astrophysics Data System (ADS)

    Hayashi, Shinichi; Takimoto, Shinichi; Hashimoto, Takeshi

    2007-02-01

    Coherent anti-Stokes Raman scattering (CARS) microscopy, which can produce images of specific molecules without staining, has attracted the attention of researchers, as it matches the need for molecular imaging and pathway analysis of live cells. In particular, there have been an increasing number of CARS experimental results regarding lipids in live cells, which cannot be fluorescently tagged while keeping the cells alive. One of the important applications of lipid research is for the metabolic syndrome. Since the metabolic syndrome is said to be related to the lipids in lipocytes, blood, arterial vessels, and so on, the CARS technique is expected to find application in this field. However, CARS microscopy requires a pair of picosecond laser pulses, which overlap both temporally and spatially. This makes the optical adjustments of a CARS microscope challenging. The authors developed a CARS unit that includes optics for easy and stable adjustment of the overlap of these laser pulses. Adding the CARS unit to a laser scanning microscope provides CARS images of a high signal-to-noise ratio, with an acquisition rate as high as 2 microseconds per pixel. Thus, images of fast-moving lipid droplets in Hela cells were obtained.

  2. Measurement of spin coherence using Raman scattering

    NASA Astrophysics Data System (ADS)

    Sun, Z.; Delteil, A.; Faelt, S.; Imamoǧlu, A.

    2016-06-01

    Ramsey interferometry provides a natural way to determine the coherence time of most qubit systems. Recent experiments on quantum dots, however, demonstrated that dynamical nuclear spin polarization can strongly influence the measurement process, making it difficult to extract the T2* coherence time using standard optical Ramsey pulses. Here, we demonstrate an alternative method for spin coherence measurement that is based on first-order coherence of photons generated in spin-flip Raman scattering. We show that if a quantum emitter is driven by a weak monochromatic laser, Raman coherence is determined exclusively by spin coherence, allowing for a direct determination of spin T2* time. When combined with coherence measurements on Rayleigh scattered photons, our technique enables us to identify coherent and incoherent contributions to resonance fluorescence, and to minimize the latter. We verify the validity of our technique by comparing our results to those determined from Ramsey interferometry for electron and heavy-hole spins.

  3. Raman imaging of extraterrestrial materials

    NASA Astrophysics Data System (ADS)

    Wang, Alian; Korotev, Randy L.; Jolliff, Bradley L.; Ling, Zongcheng

    2015-07-01

    Laser Raman Spectroscopy has been proposed and is under extensive development for surface exploration missions to planetary bodies of our Solar System. It reveals information on molecular structure and chemistry. The spatial distribution of molecular species in natural geological samples and planetary materials has significance for the geological processes by which they formed. Raman imaging is the best way to combine the molecular identification and characterization of geologic materials with their spatial distribution. This paper reports Raman imaging studies of five types of extraterrestrial materials and three terrestrial samples using a state-of-the-art Raman imaging system. The Raman spectral features of major, minor, and trace species in these samples, together with their spatial correlations revealed by these Raman imaging studies indicate the genetic relationships and the geological processes that these materials have been experienced. For robotic planetary surface exploration mission, a simple yet very useful molecular map of a sample can be generated by using line-scan or grid-scan of an in situ Raman system with tightly focused laser beam.

  4. Raman Forward Scattering in Plasma Channels

    SciTech Connect

    G. Shvets; X. Li

    2000-11-14

    Raman scattering instability of an intense laser pulse in a plasma channel proceeds differently than in a homogeneous plasma: the growth rate is reduced and the scaling with the laser intensity modified. These differences, significant even for shallow plasma channels, arise because of the radial shear of the plasma frequency and the existence of the weakly damped hybrid (electrostatic/electromagnetic) modes of the radially inhomogeneous plasma. The interplay of these two effects produces double-peaked spectra for the direct forward scattering in a channel.

  5. Label-free imaging of Drosophila in vivo by coherent anti-Stokes Raman scattering and two-photon excitation autofluorescence microscopy

    NASA Astrophysics Data System (ADS)

    Chien, Cheng-Hao; Chen, Wei-Wen; Wu, June-Tai; Chang, Ta-Chau

    2011-01-01

    Drosophila is one of the most valuable model organisms for studying genetics and developmental biology. The fat body in Drosophila, which is analogous to the liver and adipose tissue in human, stores lipids that act as an energy source during its development. At the early stages of metamorphosis, the fat body remodeling occurs involving the dissociation of the fat body into individual fat cells. Here we introduce a combination of coherent anti-Stokes Raman scattering (CARS) and two-photon excitation autofluorescence (TPE-F) microscopy to achieve label-free imaging of Drosophila in vivo at larval and pupal stages. The strong CARS signal from lipids allows direct imaging of the larval fat body and pupal fat cells. In addition, the use of TPE-F microscopy allows the observation of other internal organs in the larva and autofluorescent globules in fat cells. During the dissociation of the fat body, the findings of the degradation of lipid droplets and an increase in autofluorescent globules indicate the consumption of lipids and the recruitment of proteins in fat cells. Through in vivo imaging and direct monitoring, CARS microscopy may help elucidate how metamorphosis is regulated and study the lipid metabolism in Drosophila.

  6. Tip enhanced Raman scattering: plasmonic enhancements for nanoscale chemical analysis

    NASA Astrophysics Data System (ADS)

    Schultz, Zachary D.; Marr, James M.; Wang, Hao

    2014-04-01

    Tip enhanced Raman scattering (TERS) is an emerging technique that uses a metalized scanning probe microscope tip to spatially localize electric fields that enhances Raman scattering enabling chemical imaging on nanometer dimensions. Arising from the same principles as surface enhanced Raman scattering (SERS), TERS offers unique advantages associated with controling the size, shape, and location of the enhancing nanostructure. In this article we discuss the correlations between current understanding of SERS and how this relates to TERS, as well as how TERS provides new understanding and insights. The relationship between plasmon resonances and Raman enhancements is emphasized as the key to obtaining optimal TERS results. Applications of TERS, including chemical analysis of carbon nanotubes, organic molecules, inorganic crystals, nucleic acids, proteins, cells and organisms, are used to illustrate the information that can be gained. Under ideal conditions TERS is capable of single molecule sensitivity and sub-nanometer spatial resolution. The ability to control plasmonic enhancements for chemical analysis suggests new experiments and opportunities to understand molecular composition and interactions on the nanoscale.

  7. Raman Scattering in the Magnetized Semiconductor Plasma

    NASA Astrophysics Data System (ADS)

    Jankauskas, Zigmantas; Kvedaras, Vygaudas; Balevičius, Saulius

    2005-04-01

    Radio frequency (RF) magnetoplasmic waves known as helicons will propagate in solid-state plasmas when a strong magnetic field is applied. In our device the helicons were excited by RFs (the range 100-2000 MHz) much higher than the helicon generation frequency (the main peak at 20 MHz). The excitation of helicons in this case may be described by the effect similar to the Combination Scattering (Raman effect) when a part of the high RF wave energy that passes through the active material is absorbed and re-emitted by the magnetized solid-state plasma. It is expedient to call this experimental device a Helicon Maser (HRM) and the higher frequency e/m field - a pumping field. In full analogy with the usual Raman maser (or laser) the magnetized semiconductor sample plays the role of active material and the connecting cable - the role of high quality external resonator.

  8. Raman Scattering in the Magnetized Semiconductor Plasma

    NASA Astrophysics Data System (ADS)

    Jankauskas, Zigmantas; Kvedaras, Vygaudas; Balevičius, Saulius

    Radio frequency (RF) magnetoplasmic waves known as helicons will propagate in solid-state plasmas when a strong magnetic field is applied. In our device the helicons were excited by RFs (the range 100-2000 MHz) much higher than the helicon generation frequency (the main peak at 20 MHz). The excitation of helicons in this case may be described by the effect similar to the Combination Scattering (Raman effect) when a part of the high RF wave energy that passes through the active material is absorbed and re-emitted by the magnetized solid-state plasma. It is expedient to call this experimental device a Helicon Maser (HRM) and the higher frequency e/m field - a pumping field. In full analogy with the usual Raman maser (or laser) the magnetized semiconductor sample plays the role of active material and the connecting cable - the role of high quality external resonator.

  9. Flexible and Transparent Surface-Enhanced Raman Scattering (SERS)-Active Metafilm for Visualizing Trace Molecules via Raman Spectral Mapping.

    PubMed

    Liu, Xiangjiang; Wang, Jingjing; Wang, Jiajun; Tang, Longhua; Ying, Yibin

    2016-06-21

    Raman spectral mapping is a powerful tool for directly visualizing the composition, structure, and distribution of molecules on any surface of interest. However, one major limitation of Raman mapping is its overlong imaging time caused by the intrinsic weak Raman signal. Here, we developed a fast Raman imaging approach based on a flexible and transparent surface-enhanced Raman scattering (SERS)-active metafilm. This particular SERS substrate can be conformably attached to a sample surface to enhance the Raman signal of analytes and the good optical transparency allow excitation and collection of signal from the backside of the substrate. Therefore, by simply attaching it to the surface of interest, a fast Raman imaging can be realized. We noticed that the imaging speed can be increased by several orders of magnitude, compared to a conventional Raman mapping approach. Importantly, the proposed approach required little or no sample preparation and exhibited good generalizability that can be performed perfectly on different surfaces. It is believed that the proposed methodology will provide new trends for chemical imaging using Raman microscopy. PMID:27219332

  10. Raman scattering in a whispering mode optical waveguide

    DOEpatents

    Kurnit, Norman A.

    1982-01-01

    A device and method for Raman scattering in a whispering mode optical waveguide. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature .rho. p for confining the beam to increase intensity. A Raman scattering medium is disposed in the optical path of the beam as it propagates along the waveguide. Raman scattering is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

  11. Phononic Molecules Studied by Raman Scattering

    SciTech Connect

    Lanzillotti-Kimura, N. D.; Fainstein, A.; Jusserand, B.; Lemaitre, A.

    2010-01-04

    An acoustic nanocavity can confine phonons in such a way that they act like electrons in an atom. By combining two of these phononic-atoms, it is possible to form a phononic 'molecule', with acoustic modes that are similar to the electronic states in a hydrogen molecule. We report Raman scattering experiments performed in a monolithic structure formed by a phononic molecule embedded in an optical cavity. The acoustic mode splitting becomes evident through both the amplification and change of selection rules induced by the optical cavity confinement. The results are in perfect agreement with photoelastic model simulations.

  12. Stimulated Raman scattering microscopy: an emerging tool for drug discovery.

    PubMed

    Tipping, W J; Lee, M; Serrels, A; Brunton, V G; Hulme, A N

    2016-04-21

    Optical microscopy techniques have emerged as a cornerstone of biomedical research, capable of probing the cellular functions of a vast range of substrates, whilst being minimally invasive to the cells or tissues of interest. Incorporating biological imaging into the early stages of the drug discovery process can provide invaluable information about drug activity within complex disease models. Spontaneous Raman spectroscopy has been widely used as a platform for the study of cells and their components based on chemical composition; but slow acquisition rates, poor resolution and a lack of sensitivity have hampered further development. A new generation of stimulated Raman techniques is emerging which allows the imaging of cells, tissues and organisms at faster acquisition speeds, and with greater resolution and sensitivity than previously possible. This review focuses on the development of stimulated Raman scattering (SRS), and covers the use of bioorthogonal tags to enhance sample detection, and recent applications of both spontaneous Raman and SRS as novel imaging platforms to facilitate the drug discovery process. PMID:26839248

  13. Stimulated Raman scattering microscopy: an emerging tool for drug discovery

    PubMed Central

    Tipping, W. J.; Lee, M.; Serrels, A.; Brunton, V. G.

    2016-01-01

    Optical microscopy techniques have emerged as a cornerstone of biomedical research, capable of probing the cellular functions of a vast range of substrates, whilst being minimally invasive to the cells or tissues of interest. Incorporating biological imaging into the early stages of the drug discovery process can provide invaluable information about drug activity within complex disease models. Spontaneous Raman spectroscopy has been widely used as a platform for the study of cells and their components based on chemical composition; but slow acquisition rates, poor resolution and a lack of sensitivity have hampered further development. A new generation of stimulated Raman techniques is emerging which allows the imaging of cells, tissues and organisms at faster acquisition speeds, and with greater resolution and sensitivity than previously possible. This review focuses on the development of stimulated Raman scattering (SRS), and covers the use of bioorthogonal tags to enhance sample detection, and recent applications of both spontaneous Raman and SRS as novel imaging platforms to facilitate the drug discovery process. PMID:26839248

  14. Theory of Raman Superradiance Imaging of Condensed Bose Gases

    NASA Astrophysics Data System (ADS)

    Uys, Hermann; Meystre, Pierre

    2006-05-01

    We investigate superradiant off-resonant Raman scattering of light from an elongated Bose-condensate of atoms. Absorption imaging of superradiant systems yields stronger image contrast than imaging of systems scattering light incoherently. However, the spatial structure of the recoiling atomic fields is not simply proportional to the initial state density. We present a multi-mode theory that reproduces the time evolving spatial features observed in absorption images and accounts for shot-to-shot fluctuations.

  15. Construction of an integrated Raman- and angular-scattering microscope.

    PubMed

    Smith, Zachary J; Berger, Andrew J

    2009-04-01

    We report on the construction of a multimodal microscope platform capable of gathering both elastically and inelastically scattered light from a 38 mum(2) region in both epi- and transillumination geometries. Simultaneous monitoring of elastic and inelastic scattering from a microscopic region allows noninvasive characterization of the chemistry and morphology of a living sample without the need for exogenous dyes or labels, thus allowing measurements to be made longitudinally in time on the same sample as it evolves naturally. A sample is illuminated either from above or below with a focused 785 nm TEM(00) mode laser beam, with elastic and inelastic scattering collected by two separate measurement arms. The measurements may be made either simultaneously, if identical illumination geometries are used, or sequentially, if the two modalities utilize opposing illumination paths. In the inelastic arm, Stokes-shifted light is dispersed by a spectrograph onto a charge-coupled device (CCD) array. In the elastic scattering collection arm, a relay system images the microscope's back aperture onto a CCD array. Postprocessing of the inelastic scattering to remove fluorescence signals yields high quality Raman spectra that report on the sample's chemical makeup. Comparison of the elastically scattered pupil images to generalized Lorenz-Mie theory yields estimated size distributions of scatterers within the sample. PMID:19405678

  16. Surface Raman scattering from effervescent magnetic peroxyborates

    NASA Astrophysics Data System (ADS)

    Walrafen, G. E.; Krishnan, P. N.; Griscom, D. L.; Munro, R.

    1982-06-01

    Surface Raman scattering using a spinning technique was investigated for solid NaBO3.4H2O and NaBO3.H2O as well as for electron bombarded peroxyborates heated for various times and at temperatures form 110-180 deg C, and for solid Na2O2 and BaO2. The Raman spectra indicate that the breakdown of peroxy groups is accompanied by the formation of trapped molecular O2. Quantitative Raman intensity data were also obtained as functions of heating time at 115 deg C for the 1556 cm-1 line from O2 and for the 890 and 705 cm-1 lines whose intensities scale with the peroxy concentration. These intensity data were treated by logistics theory, and they were found to be consistent with a second-order auto-catalyzed forward reaction dependent on the product of the peroxy and O2 concentrations, plus a first-order reverse reaction dependent only on the O2 concentration.

  17. Surface Raman scattering from effervescent magnetic peroxyborates

    NASA Astrophysics Data System (ADS)

    Walrafen, G. E.; Krishnan, P. N.; Hokmabadi, M.; Griscom, D. L.; Munro, R. G.

    1982-10-01

    Surface Raman scattering using a spinning technique was investigated for solid NaBO3ṡ4H2O and NaBO3ṡH2O, as well as for electron bombarded peroxyborates, for peroxyborates heated for various times and at temperatures for 110-180 °C, and for solid Na2O2 and BaO2. The Raman spectra indicate that the breakdown of peroxy groups is accompanied by the formation of trapped molecular O2. Quantitative Raman intensity data were also obtained as functions of heating time at 115 °C for the 1556 cm-1 line from O2 and for the 890 and 705 cm-1 lines whose intensities scale with the peroxy concentration. These intensity data were treated by logistics theory, and they were found to be consistent with a second-order autocatalyzed forward reaction dependent on the product of the peroxy and O2 concentrations, plus a first-order reverse reaction dependent only on the O2 concentration.

  18. Enhanced Raman scattering of biological molecules

    NASA Astrophysics Data System (ADS)

    Montoya, Joseph R.

    The results presented in this thesis, originate from the aspiration to develop an identification algorithm for Salmonella enterica Serovar Enteritidis (S. enterica), Escherichia coli (E. coli), Bacillus globigii ( B. globigii), and Bacillus megaterium ( B. megaterium) using "enhanced" Raman scattering. We realized our goal, with a method utilizing an immunoassay process in a spectroscopic technique, and the direct use of the enhanced spectral response due to bacterial surface elements. The enhanced Raman signal originates from Surface Enhanced Raman Scattering (SERS) and/or Morphological Dependent Resonances (MDR's). We utilized a modified Lee-Meisel colloidal production method to produce a SERS active substrate, which was applied to a SERS application for the amino acid Glycine. The comparison indicates that the SERS/FRACTAL/MDR process can produce an increase of 107 times more signal than the bulk Raman signal from Glycine. In the extension of the Glycine results, we studied the use of SERS related to S. enterica, where we have shown that the aromatic amino acid contribution from Phenylalanine, Tyrosine, and Tryptophan produces a SERS response that can be used to identify the associated SERS vibrational modes of a S. enterica one or two antibody complexes. The "fingerprint" associated with the spectral signature in conjunction with an enhanced Raman signal allows conclusions to be made: (1) about the orientation of the secondary structure on the metal; (2) whether bound/unbound antibody can be neglected; (3) whether we can lower the detection limit. We have lowered the detection limit of S. enterica to 106 bacteria/ml. We also show a profound difference between S. enterica and E. coli SERS spectra even when there exists non-specific binding on E. coli indicating a protein conformation change induced by the addition of the antigen S. enterica. We confirm TEM imagery data, indicating that the source of the aromatic amino acid SERS response is originating from

  19. Raman scattering of hydrogen- and deuterium-implanted cadmium fluoride

    SciTech Connect

    Stutzmann, M.; Tatarkiewicz, J.

    1987-11-01

    The effects of proton and deuteron implantation on the Raman spectra of CdF/sub 2/ crystals have been investigated. It is found that Raman scattering can provide a quantitative measure for the structural damage caused by the implantation procedure. These results also elucidate the intrinsic or extrinsic origin of Raman peaks observed in semiconducting CdF/sub 2/.

  20. Detection of latent prints by Raman imaging

    SciTech Connect

    Lewis, Linda Anne; Connatser, Raynella Magdalene; Lewis, Sr., Samuel Arthur

    2011-01-11

    The present invention relates to a method for detecting a print on a surface, the method comprising: (a) contacting the print with a Raman surface-enhancing agent to produce a Raman-enhanced print; and (b) detecting the Raman-enhanced print using a Raman spectroscopic method. The invention is particularly directed to the imaging of latent fingerprints.

  1. Label-Free Chemical Imaging of Catalytic Solids by Coherent Anti-Stokes Raman Scattering and Synchrotron-Based Infrared Microscopy

    SciTech Connect

    Kox, M.; Domke, K; Day, J; Rago, G; Stavitski, E; Bonn, M; Weckhuysen, B

    2009-01-01

    Take a look inside: The combination of coherent anti-Stokes Raman scattering and synchrotron-based IR microscopy during the catalytic conversion of thiophene derivatives on zeolite crystals yields space- and time-resolved chemically specific information without the need for labeling (see picture). The thiophene reactant is mostly present in the center of the crystal, and the product is aligned within the straight pores of the zeolites.

  2. Planning, performing and analyzing X-ray Raman scattering experiments

    PubMed Central

    Sahle, Ch. J.; Mirone, A.; Niskanen, J.; Inkinen, J.; Krisch, M.; Huotari, S.

    2015-01-01

    A compilation of procedures for planning and performing X-ray Raman scattering (XRS) experiments and analyzing data obtained from them is presented. In particular, it is demonstrated how to predict the overall shape of the spectra, estimate detection limits for dilute samples, and how to normalize the recorded spectra to absolute units. In addition, methods for processing data from multiple-crystal XRS spectrometers with imaging capability are presented, including a super-resolution method that can be used for direct tomography using XRS spectra as the contrast. An open-source software package with these procedures implemented is also made available. PMID:25723942

  3. Planning, performing and analyzing X-ray Raman scattering experiments.

    PubMed

    Sahle, Ch J; Mirone, A; Niskanen, J; Inkinen, J; Krisch, M; Huotari, S

    2015-03-01

    A compilation of procedures for planning and performing X-ray Raman scattering (XRS) experiments and analyzing data obtained from them is presented. In particular, it is demonstrated how to predict the overall shape of the spectra, estimate detection limits for dilute samples, and how to normalize the recorded spectra to absolute units. In addition, methods for processing data from multiple-crystal XRS spectrometers with imaging capability are presented, including a super-resolution method that can be used for direct tomography using XRS spectra as the contrast. An open-source software package with these procedures implemented is also made available. PMID:25723942

  4. Compressive coherent anti-Stokes Raman scattering holography.

    PubMed

    Cocking, Alexander; Mehta, Nikhil; Shi, Kebin; Liu, Zhiwen

    2015-09-21

    Coherent anti-Stokes Raman scattering (CARS) holography captures both the amplitude and the phase of the anti-Stokes field generated from a sample and can thus perform single-shot, chemically selective three-dimensional imaging. We present compressive CARS holography, a numerical technique based on the concept of compressive sensing, to improve the quality of reconstructed images by leveraging sparsity in the source distribution and reducing the out-of-focus background noise. In particular, we use the two-step iterative shrinkage threshold (TwIST) algorithm with an l1 norm regularizer to iteratively retrieve images from an off axis CARS digital hologram. It is shown that the use of compressive CARS holography enhances the CARS holographic imaging technique by reducing noise and thereby effectively emulating a higher axial resolution using only a single shot hologram. PMID:26406699

  5. Theory of raman scattering from molecules adsorbed at semiconductor surfaces

    NASA Astrophysics Data System (ADS)

    Ueba, H.

    1983-09-01

    A theory is presented to calculate the Raman polarizability of an adsorbed molecule at a semiconductor surface, where the electronic excitation in the molecular site interacts with excitons (elementary excitations in the semiconductor) through non-radiative energy transfer between them, in an intermediate state in the Raman scattering process. The Raman polarizability thus calculated is found to exhibit a peak at the energy corresponding to a resonant excitation of excitons, thereby suggesting the possibility of surface enhanced Raman scattering on semiconductor surfaces. The mechanism studied here can also give an explanation of a recent observation of the Raman excitation profiles of p-NDMA and p-DMAAB adsorbed on ZnO or TiO 2, where those profiles were best described by assuming a resonant intermediate state of the exciton transition in the semiconductors. It is also demonstrated that in addition to vibrational Raman scattering, excitonic Raman scattering of adsorbed molecules will occur in the coupled molecule-semiconductor system, where the molecular returns to its ground electronic state by leaving an exciton in the semiconductor. A spectrum of the excitonic Raman scattering is expected to appear in the background of the vibrational Raman band and to be characterized by the electronic structure of excitons. A desirable experiment is suggested for an examination of the theory.

  6. Raman scattering mediated by neighboring molecules

    NASA Astrophysics Data System (ADS)

    Williams, Mathew D.; Bradshaw, David S.; Andrews, David L.

    2016-05-01

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process.

  7. Raman scattering mediated by neighboring molecules.

    PubMed

    Williams, Mathew D; Bradshaw, David S; Andrews, David L

    2016-05-01

    Raman scattering is most commonly associated with a change in vibrational state within individual molecules, the corresponding frequency shift in the scattered light affording a key way of identifying material structures. In theories where both matter and light are treated quantum mechanically, the fundamental scattering process is represented as the concurrent annihilation of a photon from one radiation mode and creation of another in a different mode. Developing this quantum electrodynamical formulation, the focus of the present work is on the spectroscopic consequences of electrodynamic coupling between neighboring molecules or other kinds of optical center. To encompass these nanoscale interactions, through which the molecular states evolve under the dual influence of the input light and local fields, this work identifies and determines two major mechanisms for each of which different selection rules apply. The constituent optical centers are considered to be chemically different and held in a fixed orientation with respect to each other, either as two components of a larger molecule or a molecular assembly that can undergo free rotation in a fluid medium or as parts of a larger, solid material. The two centers are considered to be separated beyond wavefunction overlap but close enough together to fall within an optical near-field limit, which leads to high inverse power dependences on their local separation. In this investigation, individual centers undergo a Stokes transition, whilst each neighbor of a different species remains in its original electronic and vibrational state. Analogous principles are applicable for the anti-Stokes case. The analysis concludes by considering the experimental consequences of applying this spectroscopic interpretation to fluid media; explicitly, the selection rules and the impact of pressure on the radiant intensity of this process. PMID:27155637

  8. Continuous-Wave Stimulated Raman Scattering (cwSRS) Microscopy

    PubMed Central

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

    2013-01-01

    Stimulated Raman scattering (SRS) microscopy is a powerful tool for chemically-sensitive non-invasive optical imaging. However, ultrafast laser sources, which are currently employed, are still expensive and require substantial maintenance to provide temporal overlap and spectral tuning. SRS imaging, which utilizes continuous-wave laser sources, has a major advantage, as it eliminates the cell damage due to exposure to the high-intensity light radiation, while substantially reducing the cost and complexity of the set-up. As a proof-of-principle, we demonstrate microscopic imaging of dimethyl sulfoxide using two independent, commonly used lasers, a diode-pumped, intracavity doubled 532-nm laser and a He-Ne laser operating at 632.8-nm PMID:24058269

  9. Solid-state Raman image amplification

    NASA Astrophysics Data System (ADS)

    Calmes, Lonnie Kirkland

    Amplification of low-light-level optical images is important for extending the range of lidar systems that image and detect objects in the atmosphere and underwater. The use of range-gating to produce images of particular range bins is also important in minimizing the image degradation due to light that is scattered backward from aerosols, smoke, or water along the imaging path. For practical lidar systems that must be operated within sight of unprotected observers, eye safety is of the utmost importance. This dissertation describes a new type of eye-safe, range-gated lidar sensing element based on Solid-state Raman Image Amplification (SSRIA) in a solid- state optical crystal. SSRIA can amplify low-level images in the eye-safe infrared at 1.556 μm with gains up to 106 with the addition of only quantum- limited noise. The high gains from SSRIA can compensate for low quantum efficiency detectors and can reduce the need for detector cooling. The range-gate of SSRIA is controlled by the pulsewidth of the pump laser and can be as short as 30-100 cm, using pump pulses of 2-6.7 nsec FWHM. A rate equation theoretical model is derived to help in the design of short pulsed Raman lasers. A theoretical model for the quantum noise properties of SSRIA is presented. SSRIA results in higher SNR images throughout a broad range of incident light levels, in contrast to the increasing noise factor with reduced gain in image intensified CCD's. A theoretical framework for the optical resolution of SSRIA is presented and it is shown that SSRIA can produce higher resolution than ICCD's. SSRIA is also superior in rejecting unwanted sunlight background, further increasing image SNR. Lastly, SSRIA can be combined with optical pre-filtering to perform optical image processing functions such as high-pass filtering and automatic target detection/recognition. The application of this technology to underwater imaging, called Marine Raman Image Amplification (MARIA) is also discussed. MARIA

  10. Rotational Raman scattering (Ring effect) in satellite backscatter ultraviolet measurements

    NASA Astrophysics Data System (ADS)

    Cebula, Richard P.; Joiner, Joanna; Bhartia, Pawan K.; Hilsenrath, Ernest; McPeters, Richard D.; Park, Hongwoo

    1995-07-01

    A detailed radiative transfer calculation has been carried out to estimate the effects of rotational Raman scattering (RRS) on satellite measurements of backscattered ultraviolet radiation. Raman-scattered light is shifted in frequency from the incident light, which causes filling in of solar Fraunhofer lines in the observed backscattered spectrum (also known as the Ring effect). The magnitude of the rotational Raman scattering filling in is a function of wavelength, solar zenith angle, surface reflectance, surface pressure, and instrument spectral resolution. The filling in predicted by our model is found to be in agreement with observations from the Shuttle Solar Backscatter Ultraviolet Radiometer and the Nimbus-7 Solar Backscatter Ultraviolet Radiometer.

  11. Ultraviolet Raman scattering from persistent chemical warfare agents

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  12. Schwinger-Keldysh canonical formalism for electronic Raman scattering

    NASA Astrophysics Data System (ADS)

    Su, Yuehua

    2016-03-01

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

  13. Raman chemical imaging using flexible fiberscope technology

    NASA Astrophysics Data System (ADS)

    Smith, Ryan D.; Nelson, Matthew P.; Treado, Patrick J.

    2000-03-01

    Raman chemical imaging microscopy has been proven to be a powerful methodology for analyzing a wide range of solid state materials. For biomedical applications, Raman chemical imaging has been shown to be effective in assessing clinical samples including breast tissue lesions and arterial plaques. With Raman chemical imaging systems based on microscopes, materials can be analyzed with molecular specificity, without labor intensive sample preparation or the use of dyes and stains at diffraction limited spatial resolution (< 250 nm). However, microscopes cannot readily be used to perform in vivo measurements. With the recent development of flexible fiberscope technology, Raman chemical imaging can be applied within remote and confined environments and the potential exists for in vivo use. This manuscript provides the first description of novel Raman chemical imaging fiberscope technology, including data analysis strategies for extracting information from Raman chemical imaging data sets.

  14. Nanopillars array for surface enhanced Raman scattering

    SciTech Connect

    S.P. Chang, A; Bora, M; Nguyen, H T; Behymer, E M; Larson, C C; Britten, J A; Carter, J C; Bond, T C

    2011-04-14

    The authors present a new class of surface-enhanced Raman scattering (SERS) substrates based on lithographically-defined two-dimensional rectangular array of nanopillars. Two types of nanopillars within this class are discussed: vertical pillars and tapered pillars. For the vertical pillars, the gap between each pair of nanopillars is small enough (< 50 nm) such that highly confined plasmonic cavity resonances are supported between the pillars when light is incident upon them, and the anti-nodes of these resonances act as three-dimensional hotspots for SERS. For the tapered pillars, SERS enhancement arises from the nanofocusing effect due to the sharp tip on top. SERS experiments were carried out on these substrates using various concentrations of 1,2 bis-(4-pyridyl)-ethylene (BPE), benzenethiol (BT) monolayer and toluene vapor. The results show that SERS enhancement factor of over 0.5 x 10{sup 9} can be achieved, and BPE can be detected down to femto-molar concentration level. The results also show promising potential for the use of these substrates in environmental monitoring of gases and vapors such as volatile organic compounds.

  15. Tip-enhanced Raman scattering of bacillus subtilis spores

    NASA Astrophysics Data System (ADS)

    Rusciano, G.; Zito, G.; Pesce, G.; Sasso, A.; Isticato, R.; Ricca, E.

    2015-07-01

    Understanding of the complex interactions of molecules at biological interfaces is a fundamental issue in biochemistry, biotechnology as well as biomedicine. A plethora of biological processes are ruled by the molecular texture of cellular membrane: cellular communications, drug transportations and cellular recognition are just a few examples of such chemically-mediated processes. Tip-Enhanced Raman Scattering (TERS) is a novel, Raman-based technique which is ideally suited for this purpose. TERS relies on the combination of scanning probe microscopy and Raman spectroscopy. The basic idea is the use of a metalled tip as a sort of optical nano-antenna, which gives place to SERS effect close to the tip end. Herein, we present the application of TERS to analyze the surface of Bacillus subtilis spores. The choice of this biological systems is related to the fact that a number of reasons support the use of spores as a mucosal delivery system. The remarkable and well-documented resistance of spores to various environmental and toxic effects make them clear potentials as a novel, surface-display system. Our experimental outcomes demonstrate that TERS is able to provide a nano-scale chemical imaging of spore surface. Moreover, we demonstrate that TERS allows differentiation between wilde-type spore and genetically modified strains. These results hold promise for the characterization and optimization of spore surface for drug-delivery applications.

  16. Enhanced spontaneous Raman scattering using a photonic crystal fiber

    SciTech Connect

    Buric, M.P.; Falk, J.; Chen, K.; Woodruff, S.D.

    2008-07-22

    The output power from spontaneous gas-phase Raman scattering is enhanced using a hollow-core photonic crystal fiber for the gas cell and Stokes light collector, yielding >100 times enhancement over a free-space configuration.

  17. Enhanced Spontaneous Raman Scattering using a Photonic Crystal Fiber

    SciTech Connect

    M.P. Buric; J. Fal; K. Chen; S. Woodruff1

    2007-10-01

    The output power from spontaneous gas-phase Raman scattering is enhanced using a hollow-core photonic crystal fiber for the gas cell and Stokes light collector, yielding >100 times enhancement over a free-space configuration.

  18. Raman scattering from rapid thermally annealed tungsten silicide

    NASA Technical Reports Server (NTRS)

    Kumar, Sandeep; Dasgupta, Samhita; Jackson, Howard E.; Boyd, Joseph T.

    1987-01-01

    Raman scattering as a technique for studying the formation of tungsten silicide is presented. The tungsten silicide films have been formed by rapid thermal annealing of thin tungsten films sputter deposited on silicon substrates. The Raman data are interpreted by using data from resistivity measurements, Auger and Rutherford backscattering measurements, and scanning electron microscopy.

  19. Light source for narrow and broadband coherent Raman scattering microspectroscopy.

    PubMed

    Brinkmann, Maximilian; Dobner, Sven; Fallnich, Carsten

    2015-12-01

    We present a light source that is well adapted to both narrow- and broadband coherent Raman scattering (CRS) methods. Based on a single oscillator, the light source delivers synchronized broadband pulses via supercontinuum generation and narrowband, frequency-tunable pulses via four-wave mixing in a photonic crystal fiber. Seeding the four-wave mixing with a spectrally filtered part of the supercontinuum yields high-pulse energies up to 8 nJ and the possibility of scanning a bandwidth of 2000  cm(-1) in 25 ms. All pulses are emitted with a repetition frequency of 1 MHz, which ensures efficient generation of CRS signals while avoiding significant damage of the samples. Consequently, the light source combines the performance of individual narrow- and broadband CRS light sources in one setup, thus enabling hyperspectral imaging and rapid single-resonance imaging in parallel. PMID:26625022

  20. Stimulated Raman side scattering in laser wakefield acceleration.

    PubMed

    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

    2010-07-16

    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. PMID:20867770

  1. Stimulated Raman Side Scattering in Laser Wakefield Acceleration

    SciTech Connect

    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.

    2010-07-16

    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.

  2. Ponderomotive potential and backward Raman scattering in dense quantum plasmas

    SciTech Connect

    Son, S.

    2014-03-15

    The backward Raman scattering is studied in dense quantum plasmas. The coefficients in the backward Raman scattering is found to be underestimated (overestimated) in the classical theory if the excited Langmuir wave has low-wave vector (high-wave vector). The second-order quantum perturbation theory shows that the second harmonic of the ponderomotive potential arises naturally even in a single particle motion contrary to the classical prediction.

  3. Dynamic Volume Holography and Optical Information Processing by Raman Scattering

    SciTech Connect

    Dodin,I.Y.; Fisch, N.J.

    2002-09-05

    A method of producing holograms of three-dimensional optical pulses is proposed. It is shown that both the amplitude and the phase profile of three-dimensional optical pulse can be stored in dynamic perturbations of a Raman medium, such as plasma. By employing Raman scattering in a nonlinear medium, information carried by a laser pulse can be captured in the form of a slowly propagating low-frequency wave that persists for a time large compared with the pulse duration. If such a hologram is then probed with a short laser pulse, the information stored in the medium can be retrieved in a second scattered electromagnetic wave. The recording and retrieving processes can conserve robustly the pulse shape, thus enabling the recording and retrieving with fidelity of information stored in optical signals. While storing or reading the pulse structure, the optical information can be processed as an analogue or digital signal, which allows simultaneous transformation of three-dimensional continuous images or computing discrete arrays of binary data. By adjusting the phase fronts of the reference pulses, one can also perform focusing, redirecting, and other types of transformation of the output pulses.

  4. Raman chemical imaging: Development and applications

    NASA Astrophysics Data System (ADS)

    Schaeberle, Michael D.

    Recent advances in electronically tunable filters, such as acousto-optic tunable filters (AOTF) and liquid crystal tunable filters (LCTF), combined with multispectral image processing strategies make Raman chemical imaging a powerful technique for the routine analysis of material chemical architecture. Raman chemical imaging combines Raman spectroscopy and digital imaging technology to assess material molecular composition and structure. Raman spectroscopy probes molecular composition and structure without being destructive to the sample. The spectrum for an analyte within even a complex host matrix is harnessed to generate unique contrast intrinsic to the analyte species without the use of stains, dyes, or contrast agents. This thesis provides a brief introduction to the field of Raman chemical imaging by describing the major methods employed. The research presented here focuses on wide field Raman imaging in conjunction with electronically tunable filters, and therefore a general methodology for performing Raman chemical imaging analysis of unknown samples is described. The AOTF and LCTF Raman chemical imaging microscopes developed during this research are also presented. The general operating principles of the AOTF and the LCTF are briefly discussed along with their specific implementation within the microscope based imaging systems. Raman chemical imaging represents an efficient, widely applicable approach for understanding the relationship between material molecular architecture and material function, which is central to the engineering of advanced materials. AOTF Raman chemical imaging has been employed in the visualization of the architecture of polypropylene and polyurethane blended polymers. High fidelity Raman images were and domains in the 3-5 mum ranges were differentiated. The AOTF Raman chemical imaging microscope has also been applied to the histopathological characterization of human breast tissue. A foreign polymer inclusion in the tissue was

  5. Probing Nanoscale Pentacene Films by Resonant Raman Scattering

    NASA Astrophysics Data System (ADS)

    He, Rui; Dujovne, Irene; Chen, Liwei; Miao, Qian; Hirjibehedin, Cyrus F.; Pinczuk, Aron; Nuckolls, Colin; Kloc, Christian; Blanchet, Graciela B.

    2005-06-01

    Resonant enhancements of Raman scattering intensities offer the sensitivity required to study nanoscale pentacene films that reach into monolayer thickness. In the results reported here structural characterization of ultra-thin layers and of their fundamental optical properties are investigated by resonant Raman scattering from intra-molecular and inter-molecular vibrations. In this work Raman methods emerge as ideal tools for the study of physics and characterization of ultra-thin nanoscale films of molecular organic materials fabricated on diverse substrates of current and future devices.

  6. Raman Scattering of Azafullerene C48N12

    SciTech Connect

    Manaa, M R

    2004-09-22

    Raman scattering activities and Raman-active frequencies are reported for the minimum energy structure of azafullerene C{sub 48}N{sub 12} at the B3LYP/6-31G* level of theory. Analysis of the vibrational spectrum shows that the most intense IR and Raman bands are those associated with C-C vibrations, and that strong IR and Raman C-N vibrations occur below 1400 cm{sup -1}. Together with the recently reported infrared, optical absorption and x-ray spectroscopies, a complete identification of this cluster should now be feasible.

  7. Solid state Raman image amplification

    NASA Astrophysics Data System (ADS)

    Calmes, Lonnie K.; Murray, James T.; Austin, William L.; Powell, Richard C.

    1998-07-01

    Lite Cycles has developed a new type of eye-safe, range-gated, lidar sensing element based on Solid-state Raman Image Amplification (SSRIA) in a solid-state optical crystal. SSRIA can amplify low-level infrared images with gains greater than 106 with the addition of only quantum-limited noise. The high gains from SSRIA can compensate for low quantum efficiency detectors and can reduce the need for detector cooling. The range-gate of SSRIA is controlled by the pulsewidth of the pump laser and can be as short as 30 - 100 cm for nanosecond pulses and less than 5 mm if picosecond pulses are used. SSRIA results in higher SNR images throughout a broad range of incident light levels, in contrast to the increasing noise factor with reduced gain in image intensified CCDs. A theoretical framework for the optical resolution of SSRIA is presented and it is shown that SSRIA can produce higher resolution than ICCDs. SSRIA is also superior in rejecting unwanted sunlight background, further increasing image SNR, and can be used for real-time optical signal processing. Applications for military use include eye-safe imaging lidars that can be used for autonomous vehicle identification and targeting.

  8. Development of a Technique for Separating Raman Scattering Signals from Background Emission with Single-Shot Measurement Potential

    NASA Technical Reports Server (NTRS)

    Hartfield, Roy J., Jr.; Dobson, Chris; Eskridge, Richard; Wehrmeyer, Joseph A.

    1997-01-01

    A novel technique for extracting Q-branch Raman signals scattered by a diatomic species from the emission spectrum resulting from the irradiation of combustion products using a broadband excimer laser has been developed. This technique is based on the polarization characteristics of vibrational Raman scattering and can be used for both single-shot Raman extraction and time-averaged data collection. The Q-branch Raman signal has a unique set of polarization characteristics which depend on the direction of the scattering while fluorescence signals are unpolarized. For the present work, a calcite crystal is used to separate the horizonal component of a collected signal from the vertical component. The two components are then sent through a UV spectrometer and imaged onto an intensified CCD camera separately. The vertical component contains both the Raman signal and the interfering fluorescence signal. The horizontal component contains the fluorescence signal and a very weak component of the Raman signal; hence, the Raman scatter can be extracted by taking the difference between the two signals. The separation of the Raman scatter from interfering fluorescence signals is critically important to the interpretation of the Raman for cases in which a broadband ultraviolet (UV) laser is used as an excitation source in a hydrogen-oxygen flame and in all hydrocarbon flames. The present work provides a demonstration of the separation of the Raman scatter from the fluorescence background in real time.

  9. Development and integration of Raman imaging capabilities to Sandia National Laboratories hyperspectral fluorescence imaging instrument.

    SciTech Connect

    Timlin, Jerilyn Ann; Nieman, Linda T.

    2005-11-01

    Raman spectroscopic imaging is a powerful technique for visualizing chemical differences within a variety of samples based on the interaction of a substance's molecular vibrations with laser light. While Raman imaging can provide a unique view of samples such as residual stress within silicon devices, chemical degradation, material aging, and sample heterogeneity, the Raman scattering process is often weak and thus requires very sensitive collection optics and detectors. Many commercial instruments (including ones owned here at Sandia National Laboratories) generate Raman images by raster scanning a point focused laser beam across a sample--a process which can expose a sample to extreme levels of laser light and requires lengthy acquisition times. Our previous research efforts have led to the development of a state-of-the-art two-dimensional hyperspectral imager for fluorescence imaging applications such as microarray scanning. This report details the design, integration, and characterization of a line-scan Raman imaging module added to this efficient hyperspectral fluorescence microscope. The original hyperspectral fluorescence instrument serves as the framework for excitation and sample manipulation for the Raman imaging system, while a more appropriate axial transmissive Raman imaging spectrometer and detector are utilized for collection of the Raman scatter. The result is a unique and flexible dual-modality fluorescence and Raman imaging system capable of high-speed imaging at high spatial and spectral resolutions. Care was taken throughout the design and integration process not to hinder any of the fluorescence imaging capabilities. For example, an operator can switch between the fluorescence and Raman modalities without need for extensive optical realignment. The instrument performance has been characterized and sample data is presented.

  10. Guiding Brain Tumor Resection Using Surface-Enhanced Raman Scattering Nanoparticles and a Hand-Held Raman Scanner

    PubMed Central

    2015-01-01

    The current difficulty in visualizing the true extent of malignant brain tumors during surgical resection represents one of the major reasons for the poor prognosis of brain tumor patients. Here, we evaluated the ability of a hand-held Raman scanner, guided by surface-enhanced Raman scattering (SERS) nanoparticles, to identify the microscopic tumor extent in a genetically engineered RCAS/tv-a glioblastoma mouse model. In a simulated intraoperative scenario, we tested both a static Raman imaging device and a mobile, hand-held Raman scanner. We show that SERS image-guided resection is more accurate than resection using white light visualization alone. Both methods complemented each other, and correlation with histology showed that SERS nanoparticles accurately outlined the extent of the tumors. Importantly, the hand-held Raman probe not only allowed near real-time scanning, but also detected additional microscopic foci of cancer in the resection bed that were not seen on static SERS images and would otherwise have been missed. This technology has a strong potential for clinical translation because it uses inert gold–silica SERS nanoparticles and a hand-held Raman scanner that can guide brain tumor resection in the operating room. PMID:25093240

  11. The Use of Spontaneous Raman Scattering for Hydrogen Leak Detection

    NASA Technical Reports Server (NTRS)

    Degroot, Wim A.

    1994-01-01

    A fiber optic probe has been built and demonstrated that utilizes back scattered spontaneous Raman spectroscopy to detect and identify gaseous species. The small probe, coupled to the laser and data acquisition equipment with optical fibers, has applications in gaseous leak detection and process monitoring. The probe design and data acquisition system are described. Raman scattering theory has been reviewed and the results of intensity calculations of hydrogen and nitrogen Raman scattering are given. Because the device is in its developmental stage, only preliminary experimental results are presented here. Intensity scans across the rotational-vibrational Raman lines of nitrogen and hydrogen are presented. Nitrogen at a partial pressure of 0.077 MPa was detected. Hydrogen at a partial pressure of 2 kPa approached the lower limit of detectability with the present apparatus. Potential instrument improvements that would allow more sensitive and rapid hydrogen detection are identified.

  12. Electro-optic contribution to Raman scattering from alkali halides

    SciTech Connect

    Mahan, G.D.; Subbaswamy, K.R.

    1986-06-15

    The electro-optic contributions to second-order Raman scattering and field-induced first-order scattering from alkali halides are calculated explicitly in terms of the ionic hyperpolarizability coefficients. The relevant local-field corrections are evaluated. Illustrative numerical results are presented.

  13. High-speed coherent Raman fingerprint imaging of biological tissues

    NASA Astrophysics Data System (ADS)

    Camp, Charles H., Jr.; Lee, Young Jong; Heddleston, John M.; Hartshorn, Christopher M.; Walker, Angela R. Hight; Rich, Jeremy N.; Lathia, Justin D.; Cicerone, Marcus T.

    2014-08-01

    An imaging platform based on broadband coherent anti-Stokes Raman scattering has been developed that provides an advantageous combination of speed, sensitivity and spectral breadth. The system utilizes a configuration of laser sources that probes the entire biologically relevant Raman window (500-3,500 cm-1) with high resolution (<10 cm-1). It strongly and efficiently stimulates Raman transitions within the typically weak ‘fingerprint’ region using intrapulse three-colour excitation, and utilizes the non-resonant background to heterodyne-amplify weak Raman signals. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues as well as interfaces between xenograft brain tumours and the surrounding healthy brain matter.

  14. Raman Imaging with a Fiber-Coupled Multichannel Spectrograph

    PubMed Central

    Schmälzlin, Elmar; Moralejo, Benito; Rutowska, Monika; Monreal-Ibero, Ana; Sandin, Christer; Tarcea, Nicolae; Popp, Jürgen; Roth, Martin M.

    2014-01-01

    Until now, spatially resolved Raman Spectroscopy has required to scan a sample under investigation in a time-consuming step-by-step procedure. Here, we present a technique that allows the capture of an entire Raman image with only one single exposure. The Raman scattering arising from the sample was collected with a fiber-coupled high-performance astronomy spectrograph. The probe head consisting of an array of 20 × 20 multimode fibers was linked to the camera port of a microscope. To demonstrate the high potential of this new concept, Raman images of reference samples were recorded. Entire chemical maps were received without the need for a scanning procedure. PMID:25420149

  15. High-Speed Coherent Raman Fingerprint Imaging of Biological Tissues

    PubMed Central

    Camp, Charles H.; Lee, Young Jong; Heddleston, John M.; Hartshorn, Christopher M.; Hight Walker, Angela R.; Rich, Jeremy N.; Lathia, Justin D.; Cicerone, Marcus T.

    2014-01-01

    An imaging platform based on broadband coherent anti-Stokes Raman scattering (BCARS) has been developed which provides an advantageous combination of speed, sensitivity and spectral breadth. The system utilizes a configuration of laser sources that probes the entire biologically-relevant Raman window (500 cm−1 to 3500 cm−1) with high resolution (< 10 cm−1). It strongly and efficiently stimulates Raman transitions within the typically weak “fingerprint” region using intrapulse 3-colour excitation, and utilizes the nonresonant background (NRB) to heterodyne amplify weak Raman signals. We demonstrate high-speed chemical imaging in two- and three-dimensional views of healthy murine liver and pancreas tissues and interfaces between xenograft brain tumours and the surrounding healthy brain matter. PMID:25621002

  16. Quantitative coherent anti-Stokes Raman scattering (CARS) microscopy.

    PubMed

    Day, James P R; Domke, Katrin F; Rago, Gianluca; Kano, Hideaki; Hamaguchi, Hiro-o; Vartiainen, Erik M; Bonn, Mischa

    2011-06-23

    The ability to observe samples qualitatively at the microscopic scale has greatly enhanced our understanding of the physical and biological world throughout the 400 year history of microscopic imaging, but there are relatively few techniques that can truly claim the ability to quantify the local concentration and composition of a sample. We review coherent anti-Stokes Raman scattering (CARS) as a quantitative, chemically specific, and label-free microscopy. We discuss the complicating influence of the nonresonant response on the CARS signal and the various experimental and mathematical approaches that can be adopted to extract quantitative information from CARS. We also review the uses to which CARS has been employed as a quantitative microscopy to solve challenges in material and biological science. PMID:21526785

  17. Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds

    PubMed Central

    Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola

    2016-01-01

    Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug delivery vehicles, and contrast agents in vivo. In the quest for superior photostability and bio-compatibility, nanodiamonds (NDs) are considered one of the best choices due to their unique structural, chemical, mechanical, and optical properties. So far, mainly fluorescent NDs have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centers with stable optical properties. Here, we show that single non-fluorescing NDs exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and ND size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of NDs internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively. PMID:25305746

  18. Coherent anti-Stokes Raman scattering microscopy of single nanodiamonds

    NASA Astrophysics Data System (ADS)

    Pope, Iestyn; Payne, Lukas; Zoriniants, George; Thomas, Evan; Williams, Oliver; Watson, Peter; Langbein, Wolfgang; Borri, Paola

    2014-11-01

    Nanoparticles have attracted enormous attention for biomedical applications as optical labels, drug-delivery vehicles and contrast agents in vivo. In the quest for superior photostability and biocompatibility, nanodiamonds are considered one of the best choices due to their unique structural, chemical, mechanical and optical properties. So far, mainly fluorescent nanodiamonds have been utilized for cell imaging. However, their use is limited by the efficiency and costs in reliably producing fluorescent defect centres with stable optical properties. Here, we show that single non-fluorescing nanodiamonds exhibit strong coherent anti-Stokes Raman scattering (CARS) at the sp3 vibrational resonance of diamond. Using correlative light and electron microscopy, the relationship between CARS signal strength and nanodiamond size is quantified. The calibrated CARS signal in turn enables the analysis of the number and size of nanodiamonds internalized in living cells in situ, which opens the exciting prospect of following complex cellular trafficking pathways quantitatively.

  19. Brillouin and Raman Scattering Study of Ethylene Glycol Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Seshimo, Y.; Ike, Y.; Kojima, S.

    2008-02-01

    We studied the cluster structure of ethylene glycol aqueous solutions by Brillouin and Raman scattering. We measured the ultrasonic sound velocity of the sample by Brillouin scattering. From the concentration dependence of the sound velocity, we studied the cluster structure in the solution. We showed that the number of H2O molecule neighboring a EG molecule becomes a little higher with increasing temperature and the intermolecular interaction between EG and H2O molecules weakened with increasing temperature. In Raman scattering study, We studied the hydrogen bond in the solution using the OD stretching band. We revealed that the strength of the hydrogen bond is independent of the EG concentration.

  20. Suppression of resonance Raman scattering via ground state depletion towards sub-diffraction-limited label-free microscopy.

    PubMed

    Rieger, Steffen; Fischedick, Markus; Boller, Klaus-Jochen; Fallnich, Carsten

    2016-09-01

    We report on the first experimental demonstration of the suppression of spontaneous Raman scattering via ground state depletion. The concept of Raman suppression can be used to achieve sub-diffraction-limited resolution in label-free microscopy by exploiting spatially selective signal suppression when imaging a sample with a combination of Gaussian- and donut-shaped beams and reconstructing a resolution-enhanced image from this data. Using a nanosecond pulsed laser source with an emission wavelength of 355 nm, the ground state of tris(bipyridine)ruthenium(II) molecules solved in acetonitrile was depleted and the spontaneous Raman scattering at 355 nm suppressed by nearly 50 %. Based on spectroscopic data retrieved from our experiment, we modeled the Raman image of a scattering center in order to demonstrate the applicability of this effect for superresolution Raman microscopy. PMID:27607677

  1. Ocean Raman Scattering in Satellite Backscatter UV Measurements

    NASA Technical Reports Server (NTRS)

    Vasilkov, Alexander P.; Joiner, Joanna; Gleason, James; Bhartia, Pawan; Bhartia, P. K. (Technical Monitor)

    2002-01-01

    Ocean Raman scattering significantly contributes to the filling-in of solar Fraunhofer lines measured by satellite backscatter ultraviolet (buy) instruments in the cloudless atmosphere over clear ocean waters. A model accounting for this effect in buy measurements is developed and compared with observations from the Global Ozone Monitoring Experiment (GONE). The model extends existing models for ocean Raman scattering to the UV spectral range. Ocean Raman scattering radiance is propagated through the atmosphere using a concept of the Lambert equivalent reflectively and an accurate radiative transfer model for Rayleigh scattering. The model and observations can be used to evaluate laboratory measurements of pure water absorption in the UV. The good agreement between model and observations suggests that buy instruments may be useful for estimating chlorophyll content.

  2. Enhancement of Raman scattering by deformation of microparticles.

    PubMed

    Sprynchak, Vitaliy; Esen, Cemal; Schweiger, Gustav

    2003-02-15

    Raman scattering on deformed droplets levitated in an acoustic levitator and produced by a vibrating-orifice aerosol generator were investigated. Our samples experiments were diethyl hexyl sebecate (DEHS) droplets in the millimeter-size range and ethanol droplets in the size range 50-100 microm. The C-H stretching region from 2800 to 3100 cm(-1) was investigated. We found that the Raman intensity measured by a scattering angle of 90 degrees depended on the shape of the droplets. Raman scattering on spherical droplets was smaller than scattering on spheroidal droplets with the same volume. Similar results were observed for the fluorescence signal of Rhodamine 6G-doped DEHS droplets. PMID:12653354

  3. Anisotropic effects in x-ray Raman scattering from graphite

    NASA Astrophysics Data System (ADS)

    Tohji, Kazuyuki; Udagawa, Yasuo; Matsushita, Tadashi; Nomura, Masaharu; Ishikawa, Tetsuya

    1990-03-01

    X-ray Raman scattering spectra from single crystal graphite were recorded. By making use of the relative directions of the scattering vector (s) and an axis of graphite crystal (c), anisotropic effects in the x-ray Raman scattering spectrum are observed; the onset of the scattering shifts by about 7 eV and the extended fine structures show significant differences in the spectra obtained for s∥c and s⊥c. Analyses by the uses of the equation employed for EXAFS show that interlayer or intralayer C-C distances can be obtained separately from the spectra for s∥c and s⊥c, respectively. This is the first observation of the anisotropy effect in the extended structure in x-ray Raman spectra.

  4. Fiber optic direct Raman imaging system based on a hollow-core fiber bundle

    NASA Astrophysics Data System (ADS)

    Inoue, S.; Katagiri, T.; Matsuura, Y.

    2015-03-01

    A Raman imaging system which combined a hollow fiber bundle and a direct imaging technique was constructed for high-speed endoscopic Raman imaging. The hollow fiber bundle is fabricated by depositing a silver thin film on the inner surface of pre-drawn glass capillary bundle. It performs as a fiber optic probe which transmits a Raman image with high signal-to-noise ratio because the propagating light is confined into the air core inducing little light scattering. The field of view on the sample is uniformly irradiated by the excitation laser light via the probe. The back-scattered image is collected by the probe and captured directly by an image sensor. A pair of thin film tunable filters is used to select target Raman band. This imaging system enables flexible and high-speed Raman imaging of biological tissues.

  5. Confocal Raman imaging of crystalline an glassy materials

    SciTech Connect

    Bradley, N.L.; Morris, M.D.

    1995-12-31

    Spatial distribution of materials components can be measured by confocal Raman imaging. We describe a confocal line-imaging system in which the spectrograph entrance slit functions as a spatial filter. The instrument uses a scanning galvanometer mirror to generate uniform intensity line illumination. A flexure mount with better than 0.1 micrometer positioning accuracy moves the sample under the fixed optical system. The Raman scatter is collected and projected along the entrance slit of an axial transmissive spectrograph. A CCD collects spatially resolved spectra.

  6. Raman scattering in a two-layer antiferromagnet

    NASA Astrophysics Data System (ADS)

    Morr, Dirk K.; Chubukov, Andrey V.; Kampf, Arno P.; Blumberg, G.

    1996-08-01

    Two-magnon Raman scattering is a useful tool to verify recent suggestions concerning the value of the interplanar exchange constant in antiferromagnetic two-layer systems, such as YBa2Cu3O6+x. We present a theory for Raman scattering in a two-layer antiferromagnet. We study the spectra for the electronic and magnetic excitations across the charge transfer gap within the one-band Hubbard model and derive the matrix elements for the Raman scattering cross section in a diagrammatic formalism. We analyze the effect of the interlayer exchange coupling J2 for the Raman spectra in A1g and B1g scattering geometries both in the nonresonant regime (when the Loudon-Fleury model is valid) and at resonance. We show that within the Loudon-Fleury approximation, a nonzero J2 gives rise to a finite signal in A1g scattering geometry. Both in this approximation and at resonance the intensity in the A1g channel has a peak at small transferred frequency equal to twice the gap in the spin-wave spectrum. We compare our results with experiments in YBa2Cu3O6.1 and Sr2CuO2Cl2 compounds and argue that the large value of J2 suggested in a number of recent studies is incompatible with Raman experiments in A1g geometry.

  7. Quantitative multi-image analysis for biomedical Raman spectroscopic imaging.

    PubMed

    Hedegaard, Martin A B; Bergholt, Mads S; Stevens, Molly M

    2016-05-01

    Imaging by Raman spectroscopy enables unparalleled label-free insights into cell and tissue composition at the molecular level. With established approaches limited to single image analysis, there are currently no general guidelines or consensus on how to quantify biochemical components across multiple Raman images. Here, we describe a broadly applicable methodology for the combination of multiple Raman images into a single image for analysis. This is achieved by removing image specific background interference, unfolding the series of Raman images into a single dataset, and normalisation of each Raman spectrum to render comparable Raman images. Multivariate image analysis is finally applied to derive the contributing 'pure' biochemical spectra for relative quantification. We present our methodology using four independently measured Raman images of control cells and four images of cells treated with strontium ions from substituted bioactive glass. We show that the relative biochemical distribution per area of the cells can be quantified. In addition, using k-means clustering, we are able to discriminate between the two cell types over multiple Raman images. This study shows a streamlined quantitative multi-image analysis tool for improving cell/tissue characterisation and opens new avenues in biomedical Raman spectroscopic imaging. PMID:26833935

  8. Surface-enhanced Raman scattering (SERS) dosimeter and probe

    DOEpatents

    Vo-Dinh, Tuan

    1995-01-01

    A dosimeter and probe for measuring exposure to chemical and biological compounds is disclosed. The dosimeter or probe includes a collector which may be analyzed by surface-enhanced Raman spectroscopy. The collector comprises a surface-enhanced Raman scattering-active material having a coating applied thereto to improve the adsorption properties of the collector. The collector may also be used in automated sequential devises, in probe array devices.

  9. Raman Scattering at Plasmonic Junctions Shorted by Conductive Molecular Bridges

    SciTech Connect

    El-Khoury, Patrick Z.; Hu, Dehong; Apkarian, V. Ara; Hess, Wayne P.

    2013-04-10

    Intensity spikes in Raman scattering, accompanied by switching between line spectra and band spectra, can be assigned to shorting the junction plasmon through molecular conductive bridges. This is demonstrated through Raman trajectories recorded at a plasmonic junction formed by a gold AFM tip in contact with a silver surface coated either with biphenyl-4,4’-dithiol or biphenyl-4-thiol. The fluctuations are absent in the monothiol. In effect, the making and breaking of chemical bonds is tracked.

  10. Surface-enhanced Raman scattering (SERS) dosimeter and probe

    DOEpatents

    Vo-Dinh, T.

    1995-03-21

    A dosimeter and probe for measuring exposure to chemical and biological compounds is disclosed. The dosimeter or probe includes a collector which may be analyzed by surface-enhanced Raman spectroscopy. The collector comprises a surface-enhanced Raman scattering-active material having a coating applied thereto to improve the adsorption properties of the collector. The collector may also be used in automated sequential devices, in probe array devices. 10 figures.

  11. Remote sensing of subsurface water temperature by Raman scattering

    NASA Technical Reports Server (NTRS)

    Leonard, D. A.; Caputo, B.; Hoge, F. E.

    1979-01-01

    The application of Raman scattering to remote sensing of subsurface water temperature and salinity is considered, and both theoretical and experimental aspects of the technique are discussed. Recent experimental field measurements obtained in coastal waters and on a trans-Atlantic/Mediterranean research cruise are correlated with theoretical expectations. It is concluded that the Raman technique for remote sensing of subsurface water temperature has been brought from theoretical and laboratory stages to the point where practical utilization can now be developed.

  12. A silver nanowire-based tip suitable for STM tip-enhanced Raman scattering.

    PubMed

    Fujita, Yasuhiko; Chiba, Rie; Lu, Gang; Horimoto, Noriko N; Kajimoto, Shinji; Fukumura, Hiroshi; Uji-i, Hiroshi

    2014-09-01

    A chemically synthesized silver nanowire was used for atomic-resolution STM imaging and tip-enhanced Raman scattering (TERS) spectroscopy, yielding excellent reproducibility. This TERS tip will open a new venue to surface analysis, such as molecular finger printing at nanoscales. PMID:24956261

  13. Ring-shaped backward stimulated Raman scattering driven by stimulated Brillouin scattering.

    PubMed

    Feng, Chengyong; Diels, Jean-Claude; Xu, Xiaozhen; Arissian, Ladan

    2015-06-29

    Backward stimulated Raman scattering is generated in water, pumped by pre-compressed pulses from a single-cell stimulated Brillouin scattering pulse compressor. The maximum energy efficiency of 9% is achieved by employing a circularly-polarized pump pulse at its energy of 50 mJ, around which point the backward stimulated Raman scattering also exhibits a ring-shaped profile. The correlations between spatial and temporal profiles as well as the intensities of the backward stimulated Raman and the stimulated Brillouin scattering generated from Raman cell indicate that the ring-shaped backward stimulated Raman is driven by intense stimulated Brillouin scattering. We demonstrate the latter process to be much more efficient for the backward Raman generation than the conventional process in which the laser itself pumps a backward stimulated Raman beam. It is shown that a further increase in pump energy leads to a drop in efficiency, combined with a break-up of the ring pattern of backward stimulated Raman. These effects are associated with filament generation above a certain threshold. PMID:26191712

  14. Raman scattering for food quality and safety assessment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growing interests in both academia and industry have driven a rapid advance in Raman spectroscopy and spectral imaging technologies during the last decade. Novel Raman measurement techniques are constantly emerging to create new detection possibilities that cannot be achieved by existing methods. Im...

  15. Coherent Scatter Imaging Measurements

    NASA Astrophysics Data System (ADS)

    Ur Rehman, Mahboob

    In conventional radiography, anatomical information of the patients can be obtained, distinguishing different tissue types, e.g. bone and soft tissue. However, it is difficult to obtain appreciable contrast between two different types of soft tissues. Instead, coherent x-ray scattering can be utilized to obtain images which can differentiate between normal and cancerous cells of breast. An x-ray system using a conventional source and simple slot apertures was tested. Materials with scatter signatures that mimic breast cancer were buried in layers of fat of increasing thickness and imaged. The result showed that the contrast and signal to noise ratio (SNR) remained high even with added fat layers and short scan times.

  16. Molecular selectivity of graphene-enhanced Raman scattering.

    PubMed

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

    2015-05-13

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

  17. Chemical Contribution to Surface-Enahanced Raman Scattering

    SciTech Connect

    Persson, Bo Nils J; Zhao, Ke; Zhang, Zhenyu

    2006-01-01

    We present a new mechanism for the chemical contribution to surface-enhanced Raman scattering (SERS). The theory considers the modulation of the polarizability of a metal nanocluster or a flat metal surface by the vibrational motion of an adsorbed molecule. The modulated polarization of the substrate coupled with the incident light will contribute to the Raman scattering enhancement. We show that for a metal cluster and for a flat metal surface this new chemical contribution may enhance the Raman scattering intensity by a factor of {approx} 10{sup 2} and {approx}10{sup 4}, respectively. The new SERS process is determined by the electric field parallel to the surface of the metal substrate at the molecular binding site.

  18. Spontaneous Raman Scattering Diagnostics for High-pressure Gaseous Flames

    NASA Technical Reports Server (NTRS)

    Kojima, Jun; Nguyen, Quang-Viet; Reddy, D. R. (Technical Monitor)

    2002-01-01

    A high-pressure (up to 60 atm) gaseous burner facility with optical access that provides steady, reproducible flames with high precision, and the ability to use multiple fuel/oxidizer combinations has been developed. In addition, a high-performance spontaneous Raman scattering system for use in the above facility has also been developed. Together, the two systems will be used to acquire and establish a comprehensive Raman scattering spectral database for use as a quantitative high-pressure calibration of single-shot Raman scattering measurements in high-pressure combustion systems. Using these facilities, the Raman spectra of H2-Air flames were successfully measured at pressures up to 20 atm. The spectra demonstrated clear rotational and ro-vibrational Raman features of H2, N2, and H2O. theoretical Raman spectra of pure rotational H2, vibrational H2, and vibrational N2 were calculated using a classical harmonic-oscillator model with pressure broadening effects and fitted to the data. At a gas temperature of 1889 K for a phi = 1.34 H2-Air flame, the model and the data showed good agreement, confirming a ro-vibrational equilibrium temperature.

  19. Remote measurements of the atmosphere using Raman scattering.

    NASA Technical Reports Server (NTRS)

    Melfi, S. H.

    1972-01-01

    Raman optical radar measurements of the atmosphere demonstrate that the technique may be used to obtain quantitative measurements of the spatial distribution of individual atmospheric molecular trace constituents (in particular water vapor) and of the major constituents. It is shown that monitoring Raman signals from atmospheric nitrogen aids in interpreting elastic scattering measurements by eliminating attenuation effects. In general, the experimental results show good agreement with independent meteorological measurements. Finally, experimental data are utilized to estimate the Raman backscatter cross section for water vapor excited at 3471.5 A.

  20. Radiation damage in NaCl. IV. Raman scattering

    SciTech Connect

    Groote, J.C.; Weerkamp, J.R.W.; Seinen, J.; den Hartog, H.W. )

    1994-10-01

    Raman-scattering experiments on heavily irradiated pure and doped NaCl crystals are described. The experiments have been performed at room temperature and at approximately 25 K. The crystals had been irradiated up to a maximum dose of 95 Grad by means of electrons from a Van de Graaff accelerator. The Raman spectra show the set of phonon peaks corresponding to the NaCl modes. At low frequencies the reduced Raman intensity shows a clear power-law dependence on the frequency, [ital I][sub red]([omega])[proportional to][omega][sup [nu

  1. Research on chirped pulse stimulated Raman scattering in ethanol

    NASA Astrophysics Data System (ADS)

    Guo, Xiao-Yang; Zou, Xiao; Xu, Yi; Lu, Xiao-Ming; Wang, Cheng; Liu, Yan-Qi; Li, Yan-Yan; Leng, Yu-Xin; Li, Ru-Xin

    2014-11-01

    We report a generation of 10.6% conversion efficiency near 1053 nm first order Stokes pulse in stimulated Raman scattering pumped using 800 nm Ti:sapphire based femtosecond pulses that are stretched to 460 ps, obtained by use of a single pass ethonal Raman shifter. The Stokes pulse almost maintains the bandwidth of the pump and is compressed to ~10 ps using a mismatched grating-pair. The spectral characteristic of the Raman pulse is calculated and the results explain the observed transient features.

  2. Oblique Raman and polariton scattering in lithium iodate

    SciTech Connect

    Falk, J.; Moshrefzadeh, R.

    1985-02-01

    The authors have predicted and measured tuning of the LO and TO oblique Raman and the oblique polariton frequencies in the 769-848 cm/sup -1/ spectral region in lithium iodate. Oblique scattering in LilO/sub 3/ is produced by coupling of A and E symmetry crystal modes. The resulting LO and TO frequencies lie between the frequencies of the contributing modes. The intensity of the scattered light observed indicates that construction of CW or quasi-CW stimulated oblique Raman and polariton oscillators are possible.

  3. Molecular alignment and orientation with a hybrid Raman scattering technique

    NASA Astrophysics Data System (ADS)

    Bustard, Philip J.; Lausten, R.; Sussman, Benjamin J.

    2012-11-01

    We demonstrate a scheme for the preparation of molecular alignment and angular momentum orientation using a hybrid combination of two limits of Raman scattering. First a weak, impulsive pump pulse initializes the system via the nonresonant dynamic Stark effect. Then, having overcome the influence of the vacuum fluctuations, an amplification pulse selectively enhances the initial coherences by transient stimulated Raman scattering, generating alignment and angular momentum orientation of molecular hydrogen. The amplitude and phase of the resulting coherent dynamics are experimentally probed, indicating an amplification factor of 4.5. An analytic theory is developed to model the dynamics.

  4. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response.

    PubMed

    Dmitriev, Pavel A; Baranov, Denis G; Milichko, Valentin A; Makarov, Sergey V; Mukhin, Ivan S; Samusev, Anton K; Krasnok, Alexander E; Belov, Pavel A; Kivshar, Yuri S

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. PMID:27113352

  5. Resonance electronic Raman scattering in rare earth crystals

    SciTech Connect

    Williams, G.M.

    1988-11-10

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

  6. Raman scattering and in-water ocean optical properties

    NASA Technical Reports Server (NTRS)

    Marshall, Bruce R.; Smith, Raymond C.

    1990-01-01

    Inelastic (transpectral) scattering may contribute significantly to the in-water light field. Major mechanisms for inelastic scattering include Raman scattering, which is important in clear ocean waters, and fluorescence from a variety of sources, which may be important in more turbid waters. The Raman cross section for liquid water is found to be 8.2 x 10 to the -30th sq cm/sr molecule, which is in agreement with the lower range of published values. Inelastic scattering has important ramifications for several aspects of marine biooptics, including the determination of in-water spectral absorption, the estimation of clear-water ocean optical properties, and possibly various aspects of algal photobiology.

  7. Nonlinearity and asymmetry of Raman scattering in crystals

    NASA Astrophysics Data System (ADS)

    Semjonow, A. Je.

    1992-09-01

    A new type of asymmetry of the spontaneous Raman scattering (ASRS) is considered for multilayered crystals ∈-GaSe (D 63h-symmetry) where not only the probabilities of light scattering are different for scattering to the right and left directions but also the phonon frequencies and phonon half-widths differ. A new ASRS has been discovered for Si-crystals (O 7h) after UV irradiation also. We showed that interface modes, chaotic behavior of the nonlinear dynamical systems and the Duffing potential renormalization driven by the noise can describe and explain the peculiarities of ASRS and give rise to ASRS in crystals. An asymmetry of the spontaneous Raman scattering in crystals represents conveniently and clearly the experimental physical model for the study of chaos in nonlinear optics.

  8. Raman scattering of IrTe2

    NASA Astrophysics Data System (ADS)

    Lee, Alexander; Thorsmolle, Verner; Artyukhin, Sergey; Yang, Jun; Cheong, Sang-Wook; Blumberg, Girsh

    2014-03-01

    IrTe2 presents a layered compound with a triangular lattice. It is known to exhibit a first order structural phase transition at approximately 260 K which is of a first order, corresponding to a formation of a superstructure with a period of five unit cells. Using polarized Raman spectroscopy we have studied the temperature dependence of 14 observed Raman allowed phononic modes. These phonons couple strongly to this transition and one additional first order transition at approximately 170 K. In the high-temperature phase only 3 modes are observed, while below approximately 280 K all 14 modes become visible. Below approximately 170 K only 11 modes are observed. Our results shed light on the possible mechanism driving the transitions. ACL, VKT and GB acknowledge support by NSF DMR-1104884.

  9. Using Raman scattering for water areas monitoring

    NASA Astrophysics Data System (ADS)

    Timchenko, E. V.; Timchenko, P. E.; Platonov, I. A.; Tregub, N. V.; Asadova, A. A.; Mukhanova, I. M.

    2016-04-01

    The results of studies on the effects of heavy metals on aquatic plants using the method of Raman spectroscopy (RS). Introduced optical coefficient, reflecting changes in chlorophyll and carotinoids in relation to the hemicellulose under the influence of heavy metals, defined as the ratio of the intensities of the RS on the wavenumbers 1547 cm-1, 1522 cm-1 to the intensity of the line 1734 cm-1. Was monitored waters of the Samara region on the basis of this coefficient.

  10. Simultaneous observation of rotational coherent Stokes Raman scattering and coherent anti-Stokes Raman scattering in air and nitrogen

    NASA Technical Reports Server (NTRS)

    Snow, J. B.; Chang, R. K.; Zheng, J. B.; Leipertz, A.

    1983-01-01

    Rotational coherent Stokes Raman scattering (CSRS) and coherent anti-Stokes Raman scattering (CARS) in air and in nitrogen were observed simultaneously by using broadband generation and detection. In the broadband technique used, the entire CARS and CSRS spectrum was generated in a single laser pulse; the CSRS and CARS signals were dispersed by a spectrograph and detected simultaneously by an optical multichannel analyzer. A three-dimensional phase-matching geometry was used to achieve spatial resolution of the CSRS and CARS beams from the input beams. Under resonant conditions, similar experiments may provide a means of investigating the possible interaction between the CSRS and CARS processes in driving the rotational levels.

  11. Raman scattering in high-{Tc} superconductors: Electronic excitations

    SciTech Connect

    Cardona, M.; Strohm, T.; Kircher, J.

    1996-12-31

    Since the discovery of the high {Tc} superconductors Raman scattering has proven to be an excellent technique to characterize them and to investigate basic physical properties relevant to the elusive mechanism responsible for their superconductivity. The authors discuss here several aspects of the technique as applied to superconductivity, including scattering by lattice vibrations, magnetic excitations, and electronic excitations, with particular emphasis on the latter, both in the normal and the superconducting state. 47 refs., 8 figs., 1 tab.

  12. Improving sensitivity in nonlinear Raman microspectroscopy imaging and sensing

    PubMed Central

    Arora, Rajan; Petrov, Georgi I.; Liu, Jian; Yakovlev, Vladislav V.

    2011-01-01

    Nonlinear Raman microspectroscopy based on a broadband coherent anti-Stokes Raman scattering is an emerging technique for noninvasive, chemically specific, microscopic analysis of tissues and large population of cells and particles. The sensitivity of this imaging is a critical aspect of a number of the proposed biomedical application. It is shown that the incident laser power is the major parameter controlling this sensitivity. By careful optimizing the laser system, the high-quality vibrational spectra acquisition at the multi-kHz rate becomes feasible. PMID:21361677

  13. Theory of coherent Raman superradiance imaging of condensed Bose gases

    NASA Astrophysics Data System (ADS)

    Uys, H.; Meystre, P.

    2007-03-01

    We describe theoretically the dynamics of the off-resonant superradiant Raman scattering of light in a prolate atomic Bose-Einstein condensate, from the initial stages governed by quantum fluctuations to the subsequent semiclassical regime, and within a multimode theory that fully accounts for propagation effects. Our results are in good agreement with recent experimental results that exploit Raman superradiance as an imaging technique to probe the long-range coherence of condensates, including the observed time-dependent spatial features, and account properly for the macroscopic shot-to-shot fluctuations resulting from the quantum noise that initiates the superradiance process.

  14. Polarized Raman scattering of single ZnO nanorod

    SciTech Connect

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

    2014-01-21

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

  15. Raman scattering and luminescence of yttria nanopowders and ceramics

    NASA Astrophysics Data System (ADS)

    Osipov, V. V.; Solomonov, V. I.; Spirina, A. V.; Vovkotrub, E. G.; Strekalovskii, V. N.

    2014-06-01

    We have studied Raman scattering in yttria nanopowders and ceramics that was excited by radiation at wavelengths of 514.5 and 632.8 nm. We show that, in undoped nanopowders and cubic phase of doped yttria ceramics, only the Raman scattering by phonons is observed, with no other Raman scattering centers having been revealed. In nanopowders of the monoclinic phase, we have observed an additional Raman line with a Raman shift of 1093 ± 4 cm-1. If all the objects under investigation are excited by the radiation at a wavelength of 514.5 nm, their spectra exhibit four series of photoluminescence lines, two of which (at λ = 521-523 and 538-564 nm) are emitted by Er3+ ions, "impurity" dopants, while the other two lines (at λ = 607-635 and 644-684 nm) are emitted by intrinsic centers. Under excitation by the radiation at a wavelength of 632.8 nm, only a series of bands at λ = 644-684 nm is emitted. In addition to these photoluminescence bands, neodymium-doped ceramics show photoluminescence bands of Nd3+ ions. We have shown that intrinsic luminescence centers, which occur in all the examined specimens, are capable of acting as acceptors with respect to neodymium ions excited to the upper laser level.

  16. Resonant Raman scattering background in XRF spectra of binary samples

    NASA Astrophysics Data System (ADS)

    Sánchez, Héctor Jorge; Leani, Juan José

    2015-02-01

    In x-ray fluorescence analysis, spectra present singular characteristics produced by the different scattering processes. When atoms are irradiated with incident energy lower and close to an absorption edge, scattering peaks appear due to an inelastic process known as resonant Raman scattering. In this work we present theoretical calculations of the resonant Raman scattering contributions to the background of x-ray fluorescence spectra of binary samples of current technological or biological interest. On one hand, a binary alloy of Fe with traces of Mn (Mn: 0.01%, Fe: 99.99%) was studied because of its importance in the stainless steels industries. On the second hand a pure sample of Ti with V traces (Ti: 99%, V: 1%) was analyzed due to the current relevance in medical applications. In order to perform the calculations the Shiraiwa and Fujino's model was used to calculate characteristic intensities and scattering interactions. This model makes certain assumptions and approximations to achieve the calculations, especially in the case of the geometrical conditions and the incident and take-off beams. For the binary sample studied in this work and the considered experimental conditions, the calculations show that the resonant Raman scattering background is significant under the fluorescent peak, affects the symmetry of the peaks and, depending on the concentrations, overcomes the enhancements contributions (secondary fluorescence).

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

    DOEpatents

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

    2014-07-22

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

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

    DOEpatents

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

    2015-07-14

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

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

    SciTech Connect

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

    2015-11-03

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

  20. Electronic Raman scattering as a probe of anisotropic electron pairing

    SciTech Connect

    Devereaux, T.P.

    1995-08-01

    A theory for the electronic contribution to Raman scattering in anisotropic superconductors is presented. It is shown that Raman scattering can provide a wealth of polarization-(symmetry-) dependent information which probes the detailed angular dependence of the energy gap. Using a model band structure, the symmetry-dependent Raman spectra are calculated for d{sub x{sup 2}{minus}y{sup 2}} pairing and compared to the data taken on Bi{sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8}. Favorable agreement with the symmetry-dependent electronic spectra is shown. Further, the impurity dependence of theory is calculated, which provides an unique test of d{sub x{sup 2}{minus}y{sup 2}} pairing.

  1. Standoff ultraviolet raman scattering detection of trace levels of explosives.

    SciTech Connect

    Kulp, Thomas J.; Bisson, Scott E.; Reichardt, Thomas A.

    2011-10-01

    Ultraviolet (UV) Raman scattering with a 244-nm laser is evaluated for standoff detection of explosive compounds. The measured Raman scattering albedo is incorporated into a performance model that focused on standoff detection of trace levels of explosives. This model shows that detection at {approx}100 m would likely require tens of seconds, discouraging application at such ranges, and prohibiting search-mode detection, while leaving open the possibility of short-range point-and-stare detection. UV Raman spectra are also acquired for a number of anticipated background surfaces: tile, concrete, aluminum, cloth, and two different car paints (black and silver). While these spectra contained features in the same spectral range as those for TNT, we do not observe any spectra similar to that of TNT.

  2. Dialkylimidazolium chloroaluminates: Ab initio calculations, Raman and neutron scattering measurements

    SciTech Connect

    Takahasi, S. ); Curtiss, L.A.; Gosztola, D.; Koura, N. ); Loong, C.K.; Saboungi, M.L. . Materials Science Div.)

    1993-04-01

    The Raman and neutron scattering spectra of 46 mol% AlCl[sub 3] -54 mol% 1-ethyl-3-methyl imidazolium chloride (EMIC) and 67 mol% AlCl[sub 3] - 33 mol% EMIC melts are presented. Ab initio molecular orbital calculations have been carried out on structures of chloroaluminate anion and EMI cation and the interaction between anion and cation.

  3. Resonant Raman scattering from silicon nanoparticles enhanced by magnetic response

    NASA Astrophysics Data System (ADS)

    Dmitriev, Pavel A.; Baranov, Denis G.; Milichko, Valentin A.; Makarov, Sergey V.; Mukhin, Ivan S.; Samusev, Anton K.; Krasnok, Alexander E.; Belov, Pavel A.; Kivshar, Yuri S.

    2016-05-01

    Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions.Enhancement of optical response with high-index dielectric nanoparticles is attributed to the excitation of their Mie-type magnetic and electric resonances. Here we study Raman scattering from crystalline silicon nanoparticles and reveal that magnetic dipole modes have a much stronger effect on the scattering than electric modes of the same order. We demonstrate experimentally a 140-fold enhancement of the Raman signal from individual silicon spherical nanoparticles at the magnetic dipole resonance. Our results confirm the importance of the optically-induced magnetic response of subwavelength dielectric nanoparticles for enhancing light-matter interactions. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr07965a

  4. Coherent Raman scattering microscopy: an emerging platform for biology and medicine (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Xie, Sunney S.

    2016-03-01

    Stimulated Raman scattering (SRS) microscopy is a label-free and noninvasive imaging technique using vibration spectroscopy as the contrast mechanism. Recent advances have allowed significant improvements in sensitivity, selectivity, robustness, and cost reduction, opening a wide range of biomedical applications. In particular, it provides instant tissue examination without the need of previous histological staining, and is best suited for imaging small metabolite molecules. An overview will be given to a variety of biomedical applications of SRS microscopy.

  5. Raman scattering in a two-layer antiferromagnet

    SciTech Connect

    Morr, D.K.; Chubukov, A.V. |; Kampf, A.P.; Blumberg, G. |

    1996-08-01

    Two-magnon Raman scattering is a useful tool to verify recent suggestions concerning the value of the interplanar exchange constant in antiferromagnetic two-layer systems, such as YBa{sub 2}Cu{sub 3}O{sub 6+{ital x}}. We present a theory for Raman scattering in a two-layer antiferromagnet. We study the spectra for the electronic and magnetic excitations across the charge transfer gap within the one-band Hubbard model and derive the matrix elements for the Raman scattering cross section in a diagrammatic formalism. We analyze the effect of the interlayer exchange coupling {ital J}{sub 2} for the Raman spectra in {ital A}{sub 1{ital g}} and {ital B}{sub 1{ital g}} scattering geometries both in the nonresonant regime (when the Loudon-Fleury model is valid) and at resonance. We show that within the Loudon-Fleury approximation, a nonzero {ital J}{sub 2} gives rise to a finite signal in {ital A}{sub 1{ital g}} scattering geometry. Both in this approximation and at resonance the intensity in the {ital A}{sub 1{ital g}} channel has a peak at {ital small} transferred frequency equal to twice the gap in the spin-wave spectrum. We compare our results with experiments in YBa{sub 2}Cu{sub 3}O{sub 6.1} and Sr{sub 2}CuO{sub 2}Cl{sub 2} compounds and argue that the large value of {ital J}{sub 2} suggested in a number of recent studies is incompatible with Raman experiments in {ital A}{sub 1{ital g}} geometry. {copyright} {ital 1996 The American Physical Society.}

  6. Achieving molecular selectivity in imaging using multiphoton Raman spectroscopy techniques

    SciTech Connect

    Holtom, Gary R. ); Thrall, Brian D. ); Chin, Beek Yoke ); Wiley, H Steven ); Colson, Steven D. )

    2000-12-01

    In the case of most imaging methods, contrast is generated either by physical properties of the sample (Differential Image Contrast, Phase Contrast), or by fluorescent labels that are localized to a particular protein or organelle. Standard Raman and infrared methods for obtaining images are based upon the intrinsic vibrational properties of molecules, and thus obviate the need for attached flurophores. Unfortunately, they have significant limitations for live-cell imaging. However, an active Raman method, called Coherent Anti-Stokes Raman Scattering (CARS), is well suited for microscopy, and provides a new means for imaging specific molecules. Vibrational imaging techniques, such as CARS, avoid problems associated with photobleaching and photo-induced toxicity often associated with the use of fluorescent labels with live cells. Because the laser configuration needed to implement CARS technology is similar to that used in other multiphoton microscopy methods, such as two -photon fluorescence and harmonic generation, it is possible to combine imaging modalities, thus generating simultaneous CARS and fluorescence images. A particularly powerful aspect of CARS microscopy is its ability to selectively image deuterated compounds, thus allowing the visualization of molecules, such as lipids, that are chemically indistinguishable from the native species.

  7. Laser sheet dropsizing based on two-dimensional Raman and Mie scattering

    SciTech Connect

    Malarski, Anna; Schuerer, Benedikt; Schmitz, Ingo; Zigan, Lars; Fluegel, Alexandre; Leipertz, Alfred

    2009-04-01

    The imaging and quantification of droplet sizes in sprays is a challenging task for optical scientists and engineers. Laser sheet dropsizing (LSDS) combines the two-dimensional information of two different optical processes, one that is proportional to the droplet volume and one that depends on the droplet surface, e.g., Mie scattering. Besides Mie scattering, here we use two-dimensional Raman scattering as the volume-dependent measurement technique. Two different calibration strategies are presented and discussed. Two-dimensional droplet size distributions in a spray have been validated in comparison with the results of point-resolved phase Doppler anemometry (PDA) measurements.

  8. Stimulated Raman Scattering from Short GaP Nanowires

    NASA Astrophysics Data System (ADS)

    Wu, Jian; Gupta, Awnish; Eklund, Peter

    2009-03-01

    We report an interesting discovery of very strong non-linear optical behavior in short GaP nanowire segments. They were formed by cutting a ˜40 μm long and 210 nm diameter GaP nanowire into various lengths using a focused ion beam. This approach allows us to study length as the variable in the non-linear behavior. A giant nonlinear Raman amplification has been observed in these segments with length L< 1.2μm for the first time. The nonlinear Raman effect has been demonstrated to increase as the lengths of nanowire segments decreases. As far as the relationship between Raman scattering intensity and laser pump power, we also observed that there exists a threshold pump laser power which separates the linear and super-linear regions. The effective pump power can be as low as 200 μW that is 1000 times smaller than bulk values. We attribute this giant nonlinear Raman effect to stimulated Raman scattering (SRS) from nanocavities formed by these short GaP nanowires. The quality factor Q of these short segments was estimated to be 10^3 to 10^4. We believe our observation suggests the possibility to make a new type of SRS semiconductor laser.

  9. Surface enhanced Raman scattering spectroscopic waveguide

    DOEpatents

    Lascola, Robert J; McWhorter, Christopher S; Murph, Simona H

    2015-04-14

    A waveguide for use with surface-enhanced Raman spectroscopy is provided that includes a base structure with an inner surface that defines a cavity and that has an axis. Multiple molecules of an analyte are capable of being located within the cavity at the same time. A base layer is located on the inner surface of the base structure. The base layer extends in an axial direction along an axial length of an excitation section. Nanoparticles are carried by the base layer and may be uniformly distributed along the entire axial length of the excitation section. A flow cell for introducing analyte and excitation light into the waveguide and a method of applying nanoparticles may also be provided.

  10. Raman Scattering in a New Carbon Material

    NASA Technical Reports Server (NTRS)

    Voronov, O. A.; Street, K. W., Jr.

    2010-01-01

    Samples of a new carbon material, Diamonite-B, were fabricated under high pressure from a commercial carbon black--identified as mixed fullerenes. The new material is neither graphite-like nor diamond-like, but exhibits electrical properties close to graphite and mechanical properties close to diamond. The use of Raman spectroscopy to investigate the vibrational dynamics of this new carbon material and to provide structural characterization of its short-, medium- and long-range order is reported. We also provide the results of investigations of these samples by high-resolution electron microscopy and X-ray diffraction. Hardness, electrical conductivity, thermal conductivity and other properties of this new material are compared with synthetic graphite-like and diamond-like materials, two other phases of synthetic bulk carbon.