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Sample records for in-situ raman imaging

  1. Novel, in-situ Raman and fluorescence measurement techniques: Imaging using optical waveguides

    NASA Astrophysics Data System (ADS)

    Carter, Jerry Chance

    The following dissertation describes the development of methods for performing standoff and in- situ Raman and fluorescence spectroscopy for chemical imaging and non-imaging analytical applications. The use of Raman spectroscopy for the in- situ identification of crack cocaine and cocaine.HCl using a fiberoptic Raman probe and a portable Raman spectrograph has been demonstrated. We show that the Raman spectra of both forms of cocaine are easily distinguishable from common cutting agents and impurities such as benzocaine and lidocaine. We have also demonstrated the use of Raman spectroscopy for in-situ identification of drugs separated by thin layer chromatography. We have investigated the use of small, transportable, Raman systems for standoff Raman spectroscopy (e.g. <20 m). For this work, acousto-optical (AOTF) and liquid crystal tunable filters (LCTF) are being used both with, and in place of dispersive spectrographs and fixed filtering devices. In addition, we improved the flexibility of the system by the use of a modified holographic fiber-optic probe for light and image collection. A comparison of tunable filter technologies for standoff Raman imaging is discussed along with the merits of image transfer devices using small diameter image guides. A standoff Raman imaging system has been developed that utilizes a unique polymer collection mirror. The techniques used to produce these mirrors make it easy to design low f/# polymer mirrors. The performance of a low f/# polymer mirror system for standoff Raman chemical imaging has been demonstrated and evaluated. We have also demonstrated remote Raman hyperspectral imaging using a dimension-reduction, 2-dimensional (2-D) to 1-dimensional (1-D), fiber optic array. In these studies, a modified holographic fiber-optic probe was combined with the dimension-reduction fiber array for remote Raman imaging. The utility of this setup for standoff Raman imaging is demonstrated by monitoring the polymerization of

  2. Image-guided Raman spectroscopic recovery of canine cortical bone contrast in situ.

    PubMed

    Srinivasan, Subhadra; Schulmerich, Matthew; Cole, Jacqueline H; Dooley, Kathryn A; Kreider, Jaclynn M; Pogue, Brian W; Morris, Michael D; Goldstein, Steven A

    2008-08-01

    Raman scattering provides valuable biochemical and molecular markers for studying bone tissue composition with use in predicting fracture risk in osteoporosis. Raman tomography can image through a few centimeters of tissue but is limited by low spatial resolution. X-ray computed tomography (CT) imaging can provide high-resolution image-guidance of the Raman spectroscopic characterization, which enhances the quantitative recovery of the Raman signals, and this technique provides additional information to standard imaging methods. This hypothesis was tested in data measured from Teflon tissue phantoms and from a canine limb. Image-guided Raman spectroscopy (IG-RS) of the canine limb using CT images of the tissue to guide the recovery recovered a contrast of 145:1 between the cortical bone and background. Considerably less contrast was found without the CT image to guide recovery. This study presents the first known IG-RS results from tissue and indicates that intrinsically high contrasts (on the order of a hundred fold) are available. PMID:18679495

  3. Sequential electrochemical unzipping of single-walled carbon nanotubes to graphene ribbons revealed by in situ Raman spectroscopy and imaging.

    PubMed

    John, Robin; Shinde, Dhanraj B; Liu, Lili; Ding, Feng; Xu, Zhiping; Vijayan, Cherianath; Pillai, Vijayamohanan K; Pradeep, Thalappil

    2014-01-28

    We report an in situ Raman spectroscopic and microscopic investigation of the electrochemical unzipping of single-walled carbon nanotubes (SWNTs). Observations of the radial breathing modes (RBMs) using Raman spectral mapping reveal that metallic SWNTs are opened up rapidly followed by gradual unzipping of semiconducting SWNTs. Consideration of the resonant Raman scattering theory suggests that two metallic SWNTs with chiralities (10, 4) and (12, 0) get unzipped first at a lower electrode potential (0.36 V) followed by the gradual unzipping of another two metallic tubes, (9, 3) and (10, 1), at a relatively higher potential (1.16 V). The semiconducting SWNTs with chiralities (11, 7) and (12, 5), however, get open up gradually at ±1.66 V. A rapid decrease followed by a subsequent gradual decrease in the metallicity of the SWNT ensemble as revealed from a remarkable variation of the peak width of the G band complies well with the variations of RBM. Cyclic voltammetry also gives direct evidence for unzipping in terms of improved capacitance after oxidation followed by more important removal of oxygen functionalities during the reduction step, as reflected in subtle changes of the morphology confirming the formation of graphene nanoribbons. The density functional-based tight binding calculations show additional dependence of chirality and diameter of nanotubes on the epoxide binding energies, which is in agreement with the Raman spectroscopic results and suggests a possible mechanism of unzipping determined by combined effects of the structural characteristics of SWNTs and applied field. PMID:24308315

  4. 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.

  5. Evaluating drug delivery with salt formation: Drug disproportionation studied in situ by ATR-FTIR imaging and Raman mapping.

    PubMed

    Ewing, Andrew V; Wray, Patrick S; Clarke, Graham S; Kazarian, Sergei G

    2015-01-01

    Two different vibrational spectroscopic approaches, ATR-FTIR spectroscopic imaging and Raman mapping, were used to investigate the components within a tablet containing an ionised drug during dissolution experiments. Delivering certain drugs in their salt form is a method that can be used to improve the bioavailability and dissolution of the poorly aqueous soluble materials. However, these ionised species have a propensity to covert back to their thermodynamically favourable free acid or base forms. Dissolution experiments of the ionised drug in different aqueous media resulted in conversion to the more poorly soluble free acid form, which is detrimental for controlled drug release. This study investigates the chemical changes occurring to formulations containing a development ionised drug (37% by weight), in different aqueous pH environments. Firstly, dissolution in a neutral medium was studied, showing that there was clear release of ionised monosodium form of the drug from the tablet as it swelled in the aqueous medium. There was no presence of any drug in the monohydrate free acid form detected in these experiments. Dissolution in an acidic (0.1M HCl) solution showed disproportionation forming the free acid form. Disproportionation occurred rapidly upon contact with the acidic solution, initially resulting in a shell of the monohydrate free acid form around the tablet edges. This slowed ingress of the solution into the tablet before full conversion of the ionised form to the free acid form was characterised in the spectroscopic data. PMID:25910459

  6. In situ cell cycle phase determination using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2010-02-01

    Raman spectroscopy is a powerful tool for analysis of the chemical composition in living tissue and cells without destructive processes such as fixation, immunostaining, and fluorescence labeling. Raman microspectroscopic technique enables us to obtain a high quality spectrum from a single living cell. We demonstrated in situ cell cycle analysis with Raman microspectroscopy with the excitation wavelength of 532 nm. Cell cycle phases, G0/G1 and G2/M were able to be identified in the present study. The result of in situ Raman analysis was evaluated with flow cytometry analysis. Although the Raman spectra of living cells showed complex patterns during cell cycle, several Raman bands could be useful as markers for the cell cycle identification. A single cell analysis using Raman microspectroscopy predicted a possibility to observe directly molecular dynamics intracellular molecules of proteins, lipids and nucleic acids. Our current study focused on cytoplasm region and resonant Raman signals of cytochrome c in mitochondrion, and discussed how the Raman signals from cellular components contribute to the Raman spectral changes in cell cycle change in the human living cell (lung cancer cell).

  7. 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.

  8. [Water Raman spectrum suppression with low-pass filter in underwater in-situ Raman spectroscopy].

    PubMed

    Guo, Jin-Jia; Liu, Zhi-Shen

    2011-09-01

    As a powerful tool for studying chemical structures, Raman spectroscopy has been used in aquatic environments in-situ measurement widely, and has been used in deep sea research recently. For underwater in-situ detection, O-H vibration Raman peak of water is inherent and strong compared with other dissolved matter's Raman signals. When the authors want to get a good SNR Raman signal of dissolved matter by increasing detection time, O-H vibration Raman peak of water will get to saturation easily, which influences other Raman signal's detection. In the present paper, a specially designed short-pass optical filter was used for suppression of water's O-H vibration Raman peak. The authors calculated the suppression effect of short-pass optical filter with linear and exponential edges. The simulation shows that exponential edge filter has better performance and can suppress water's O-H vibration Raman peak effectively. The experiment also proves the calculation results. With the suppression optical filter, the intensity of water's O-H vibration Raman signal and other dissolved matters' become similar. And the influence of suppression optical filter on other dissolved matters' Raman signal is little. So the suppression optical filter is feasible for in-situ underwater Raman spectroscopy. PMID:22097842

  9. Raman spectroscopy for in-situ monitoring of electrode processes

    SciTech Connect

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

    1982-04-01

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

  10. In Situ Detection of Antibiotic Amphotericin B Produced in Streptomyces nodosus Using Raman Microspectroscopy

    PubMed Central

    Miyaoka, Rimi; Hosokawa, Masahito; Ando, Masahiro; Mori, Tetsushi; Hamaguchi, Hiro-o; Takeyama, Haruko

    2014-01-01

    The study of spatial distribution of secondary metabolites within microbial cells facilitates the screening of candidate strains from marine environments for functional metabolites and allows for the subsequent assessment of the production of metabolites, such as antibiotics. This paper demonstrates the first application of Raman microspectroscopy for in situ detection of the antifungal antibiotic amphotericin B (AmB) produced by actinomycetes—Streptomyces nodosus. Raman spectra measured from hyphae of S. nodosus show the specific Raman bands, caused by resonance enhancement, corresponding to the polyene chain of AmB. In addition, Raman microspectroscopy enabled us to monitor the time-dependent change of AmB production corresponding to the growth of mycelia. The Raman images of S. nodosus reveal the heterogeneous distribution of AmB within the mycelia and individual hyphae. Moreover, the molecular association state of AmB in the mycelia was directly identified by observed Raman spectral shifts. These findings suggest that Raman microspectroscopy could be used for in situ monitoring of antibiotic production directly in marine microorganisms with a method that is non-destructive and does not require labeling. PMID:24828290

  11. Analysis of Surface Leaching Processes in Vitrified High-Level Nuclear Wastes Using In-Situ Raman Imaging and Atomistic Modeling - Final Report

    SciTech Connect

    Simmons, Joseph H.

    2001-04-24

    The in situ analysis of surface conditions of vitrified nuclear wastes can provide an important check of the burial status of radioactive objects without risk of radiation exposure. Raman spectroscopy was initially chosen as the most promising method for testing the surface conditions of glasses undergoing chemical corrosion, and was used extensively during the first year. However, it was determined that infrared reflection spectroscopy was better suited to this particular need and was used for the remaining two years to investigate the surface corrosion behavior of model silicate glasses for extension to nuclear waste glasses. The developed methodology is consistent with the known theory of optical propagation of dielectric media and uses the Kramers-Kronig formalism. The results show that it is possible to study the corrosion of glass by analyzing the glass surface using reflection fast Fourier infrared measurements and the newly developed ''dispersion analysis method.'' The data show how this analysis can be used to monitor the corrosion behavior of vitrified waste glasses over extended periods of storage.

  12. Indentation device for in situ Raman spectroscopic and optical studies

    NASA Astrophysics Data System (ADS)

    Gerbig, Y. B.; Michaels, C. A.; Forster, A. M.; Hettenhouser, J. W.; Byrd, W. E.; Morris, D. J.; Cook, R. F.

    2012-12-01

    Instrumented indentation is a widely used technique to study the mechanical behavior of materials at small length scales. Mechanical tests of bulk materials, microscopic, and spectroscopic studies may be conducted to complement indentation and enable the determination of the kinetics and physics involved in the mechanical deformation of materials at the crystallographic and molecular level, e.g., strain build-up in crystal lattices, phase transformations, and changes in crystallinity or orientation. However, many of these phenomena occurring during indentation can only be observed in their entirety and analyzed in depth under in situ conditions. This paper describes the design, calibration, and operation of an indentation device that is coupled with a Raman microscope to conduct in situ spectroscopic and optical analysis of mechanically deformed regions of Raman-active, transparent bulk material, thin films or fibers under contact loading. The capabilities of the presented device are demonstrated by in situ studies of the indentation-induced phase transformations of Si thin films and modifications of molecular conformations in high density polyethylene films.

  13. Water monitoring by optofluidic Raman spectroscopy for in situ applications.

    PubMed

    Persichetti, Gianluca; Bernini, Romeo

    2016-08-01

    The feasibility of water monitoring by Raman spectroscopy with a portable optofluidic system for in-situ applications has been successfully demonstrated. In the proposed approach, the sample under analysis is injected into a capillary nozzle in order to produce a liquid jet that acts as an optical waveguide. This jet waveguide provides an effective strategy to excite and collect the Raman signals arising from water contaminants due to the high refractive index difference between air and water. The proposed approach avoids any necessity of liquid container or flow cell and removes any background signal coming from the sample container commonly affects Raman measurements. Furthermore, this absence is a significant advantage for in situ measurements where fouling problems can be relevant and cleaning procedures are troublesome. The extreme simplicity and efficiency of the optical scheme adopted in our approach result in highly sensitive and rapid measurements that have been performed on different representative water pollutants. The experimental results demonstrate the high potentiality of our device in water quality monitoring and analysis. In particular, nitrate and sulfate are detected below the maximum contamination level allowed for drinking water, whereas a limit of detection of 40mg/l has been found for benzene. PMID:27216667

  14. In situ microscopic studies on the structures and phase behaviors of SF/PEG films using solid-state NMR and Raman imaging.

    PubMed

    Chen, Congheng; Yao, Ting; Tu, Sidong; Xu, Weijie; Han, Yi; Zhou, Ping

    2016-06-28

    In order to overcome the drawbacks of silk fibroin (SF)-based materials, SF has been blended with some polymers. Before using the blend material, understanding of the structures and phase behaviors of the blend is thought to be essential. In this study, solid-state (13)C CP-MAS NMR and Raman imaging techniques were used to study the structures and phase behaviors of blends of SF with polyethylene glycol (PEG) at a molecular weight that varied from 2 to 20 kDa and a blend ratio of SF/PEG from 95/5 to 70/30 (w/w%) at the molecular and microscopic levels. It is found that the conformational transition of SF to the β-sheet increased as the PEG content increased, while the amount of the formed β-sheet conformers was decreased as the PEG molecular weight increased for a given content. It is also observed that SF was incompatible with PEG to some extent. The phase separation into "sea" and "island" domains took place in the SF/PEG blend films. SF was dominantly present in the "sea" domain, while PEG in the "island" domains. The conformation of SF in the interface between SF and PEG was changed to the β-sheet, while that in the protein-rich domain remained in the random coil and/or helix conformation. These observations suggest that the specifically expected materials, for example, the silk-based microspheres or scaffold materials can be manufactured by controlling the molecular weight and content of PEG in the blend system. PMID:27255417

  15. 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

  16. Synthesis and in situ high pressure Raman spectroscopy study of AlN dendritic crystal

    SciTech Connect

    Li, Xuefei; Kong, Lingnan; Shen, Longhai; Yang, Jinghai; Gao, Ming; Hu, Tingjing; Wu, Xingtong; Li, Ming

    2013-09-01

    Graphical abstract: - Highlights: • The sample is the typical dendritic crystal structure. • The phase transition of AlN dendritic crystal is researched. • The Raman signal of rock salt AlN is observed under high pressure. • Grüneisen parameters and phase transition criterion are discussed. - Abstract: AlN dendritic crystal was synthesized by the direct current arc discharge apparatus. X-ray diffraction (XRD) patterns indicated that the sample is hexagonal AlN and preferentially grown along the a-axis direction. Scanning electron microscopy (SEM) and Transmission electron microscopy (TEM) images reveal that the product mainly consists of micron AlN dendritic crystal. In situ high pressure Raman spectra of AlN dendritic crystal has been measured in the pressure ranged from ambient pressure to 32.97 GPa at room temperature by using diamond anvil cell. According to the Raman scattering results, the phase transition from the wurtzite to rock salt was found at about 20.73 GPa by the appearance of a new Raman signal. Above 20.73 GPa, a new Raman signal due to disorder-activated Raman scattering in the rock salt phase was observed. In addition, the pressure coefficients, phase transition criterion, and mode Grüneisen parameters of AlN dendritic crystal, which could be different from that of other AlN, are carefully discussed.

  17. FINAL REPORT. ANALYSIS OF SURFACE LEACHING PROCESSES IN VITRIFIED HIGH-LEVEL NUCLEAR WASTES USING IN-SITU RAMAN IMAGING AND ATOMISTIC MODELING

    EPA Science Inventory

    The in-situ analysis of surface conditions of vitrified nuclear wastes can provide animportant check of the burial status of these radioactive objects without risk of radiationexposure. This check could be conducted over time and be used to monitor conditions in a storage site....

  18. In Situ Imaging of Atomic Quantum Gases

    NASA Astrophysics Data System (ADS)

    Hung, Chen-Lung; Chin, Cheng

    2015-09-01

    One exciting progress in recent cold atom experiments is the development of high resolution, in situ imaging techniques for atomic quantum gases.1-3 These new powerful tools provide detailed information on the distribution of atoms in a trap with resolution approaching the level of single atom and even single lattice site, and complement the welldeveloped time-of-flight method that probes the system in momentum space. In a condensed matter analogy, this technique is equivalent to locating electrons of a material in a snap shot. In situ imaging has offered a new powerful tool to study atomic gases and inspired many new research directions and ideas. In this chapter, we will describe the experimental setup of in situ absorption imaging, observables that can be extracted from the images, and new physics that can be explored with this technique.

  19. Note: Raman microspectroscopy integrated with fluorescence and dark field imaging

    NASA Astrophysics Data System (ADS)

    Li, Haibo; Wang, Hailong; Huang, Dianshuai; Liang, Lijia; Gu, Yuejiao; Liang, Chongyang; Xu, Shuping; Xu, Weiqing

    2014-05-01

    A Raman detection platform integrated with both fluorescence and dark field microscopes was built for in situ Raman detection with the assistance of fluorescence and dark field imaging to locate the target micro regions. Cells and organelles can be easily found via fluorescence imaging with labeling techniques. Besides, nano-sized particles could be observed and located by dark field microscopes. Therefore, comparing with the commercial Raman spectrometers, much more researches based on Raman spectroscopy could be carried out on this integrated Raman platform, especially in the fields of analyzing biological tissues and subwavelength samples.

  20. Raman spectroscopy and in situ Raman spectroelectrochemistry of isotopically engineered graphene systems.

    PubMed

    Frank, Otakar; Dresselhaus, Mildred S; Kalbac, Martin

    2015-01-20

    CONSPECTUS: The special properties of graphene offer immense opportunities for applications to many scientific fields, as well as societal needs, beyond our present imagination. One of the important features of graphene is the relatively simple tunability of its electronic structure, an asset that extends the usability of graphene even further beyond present experience. A direct injection of charge carriers into the conduction or valence bands, that is, doping, represents a viable way of shifting the Fermi level. In particular, electrochemical doping should be the method of choice, when higher doping levels are desired and when a firm control of experimental conditions is needed. In this Account, we focus on the electrochemistry of graphene in combination with in situ Raman spectroscopy, that is, in situ Raman spectroelectrochemistry. Such a combination of methods is indeed very powerful, since Raman spectroscopy not only can readily monitor the changes in the doping level but also can give information on eventual stress or disorder in the material. However, when Raman spectroscopy is employed, one of its main strengths lies in the utilization of isotope engineering during the chemical vapor deposition (CVD) growth of the graphene samples. The in situ Raman spectroelectrochemical study of multilayered systems with smartly designed isotope compositions in individual layers can provide a plethora of knowledge about the mutual interactions (i) between the graphene layers themselves, (ii) between graphene layers and their directly adjacent environment (e.g., substrate or electrolyte), and (iii) between graphene layers and their extended environment, which is separated from the layer by a certain number of additional graphene layers. In this Account, we show a few examples of such studies, from monolayer to two-layer and three-layer specimens and considering both turbostratic and AB interlayer ordering. Furthermore, the concept and the method can be extended further

  1. Waterproofing in Arabidopsis: Following phenolics and lipids in situ by Confocal Raman Microscopy

    NASA Astrophysics Data System (ADS)

    Prats Mateu, Batirtze; Hauser, Marie-Theres; Heredia, Antonio; Gierlinger, Notburga

    2016-02-01

    Waterproofing of the aerial organs of plants imposed a big evolutionary step during the colonization of the terrestrial environment. The main plant polymers responsible of water repelling are lipids and lignin, which play also important roles in the protection against biotic/abiotic stresses, regulation of flux of gases and solutes and mechanical stability against negative pressure, among others. While the lipids, non-polymerized cuticular waxes together with the polymerized cutin, protect the outer surface, lignin is confined to the secondary cell wall within mechanical important tissues. In the present work a micro cross-section of the stem of Arabidopsis thaliana was used to track in situ the distribution of these non-carbohydrate polymers by Confocal Raman Microscopy. Raman hyperspectral imaging gives a molecular fingerprint of the native waterproofing tissues and cells with diffraction limited spatial resolution (~300 nm) at relatively high speed and without any tedious sample preparation. Lipids and lignified tissues as well as their effect on water content was directly visualized by integrating the 1299 cm-1, 1600 cm-1 and 3400 cm-1 band, respectively. For detailed insights into compositional changes of these polymers vertex component analysis was performed on selected sample positions. Changes have been elucidated in the composition of lignin within the lignified tissues and between interfascicular fibers and xylem vessels. Hydrophobising changes were revealed from the epidermal layer to the cuticle as well as a change in the aromatic composition within the cuticle of trichomes. To verify Raman signatures of different waterproofing polymers additionally Raman spectra of the cuticle and cutin monomer from tomato (Solanum lycopersicum) as well as aromatic model polymers (milled wood lignin and dehydrogenation polymer of coniferyl alcohol) and phenolic acids were acquired. Keywords: Arabidopsis thaliana, lignin, cutin, wax, Raman, cuticle, waterproofing

  2. Support Routines for In Situ Image Processing

    NASA Technical Reports Server (NTRS)

    Deen, Robert G.; Pariser, Oleg; Yeates, Matthew C.; Lee, Hyun H.; Lorre, Jean

    2013-01-01

    This software consists of a set of application programs that support ground-based image processing for in situ missions. These programs represent a collection of utility routines that perform miscellaneous functions in the context of the ground data system. Each one fulfills some specific need as determined via operational experience. The most unique aspect to these programs is that they are integrated into the large, in situ image processing system via the PIG (Planetary Image Geometry) library. They work directly with space in situ data, understanding the appropriate image meta-data fields and updating them properly. The programs themselves are completely multimission; all mission dependencies are handled by PIG. This suite of programs consists of: (1)marscahv: Generates a linearized, epi-polar aligned image given a stereo pair of images. These images are optimized for 1-D stereo correlations, (2) marscheckcm: Compares the camera model in an image label with one derived via kinematics modeling on the ground, (3) marschkovl: Checks the overlaps between a list of images in order to determine which might be stereo pairs. This is useful for non-traditional stereo images like long-baseline or those from an articulating arm camera, (4) marscoordtrans: Translates mosaic coordinates from one form into another, (5) marsdispcompare: Checks a Left Right stereo disparity image against a Right Left disparity image to ensure they are consistent with each other, (6) marsdispwarp: Takes one image of a stereo pair and warps it through a disparity map to create a synthetic opposite- eye image. For example, a right eye image could be transformed to look like it was taken from the left eye via this program, (7) marsfidfinder: Finds fiducial markers in an image by projecting their approximate location and then using correlation to locate the markers to subpixel accuracy. These fiducial markets are small targets attached to the spacecraft surface. This helps verify, or improve, the

  3. 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...

  4. [Application of in situ cryogenic Raman spectroscopy to analysis of fluid inclusions in reservoirs].

    PubMed

    Chen, Yong; Lin, Cheng-yan; Yu, Wen-quan; Zheng, Jie; Wang, Ai-guo

    2010-01-01

    Identification of salts is a principal problem for analysis of fluid inclusions in reservoirs. The fluid inclusions from deep natural gas reservoirs in Minfeng sub-sag were analyzed by in situ cryogenic Raman spectroscopy. The type of fluid inclusions was identified by Raman spectroscopy at room temperature. The Raman spectra show that the inclusions contain methane-bearing brine aqueous liquids. The fluid inclusions were analyzed at -180 degrees C by in situ cryogenic Raman spectroscopy. The spectra show that inclusions contain three salts, namely NaCl2, CaCl2 and MgCl2. Sodium chloride is most salt component, coexisting with small calcium chloride and little magnesium chloride. The origin of fluids in inclusions was explained by analysis of the process of sedimentation and diagenesis. The mechanism of diagenesis in reservoirs was also given in this paper. The results of this study indicate that in situ cryogenic Raman spectroscopy is an available method to get the composition of fluid inclusions in reservoirs. Based on the analysis of fluid inclusions in reservoirs by in situ cryogenic Raman spectroscopy with combination of the history of sedimentation and diagenesis, the authors can give important evidence for the type and mechanism of diagenesis in reservoirs. PMID:20302090

  5. Waterproofing in Arabidopsis: Following Phenolics and Lipids In situ by Confocal Raman Microscopy

    PubMed Central

    Prats Mateu, Batirtze; Hauser, Marie Theres; Heredia, Antonio; Gierlinger, Notburga

    2016-01-01

    Waterproofing of the aerial organs of plants imposed a big evolutionary step during the colonization of the terrestrial environment. The main plant polymers responsible of water repelling are lipids and lignin, which play also important roles in the protection against biotic/abiotic stresses, regulation of flux of gases and solutes, and mechanical stability against negative pressure, among others. While the lipids, non-polymerized cuticular waxes together with the polymerized cutin, protect the outer surface, lignin is confined to the secondary cell wall within mechanical important tissues. In the present work a micro cross-section of the stem of Arabidopsis thaliana was used to track in situ the distribution of these non-carbohydrate polymers by Confocal Raman Microscopy. Raman hyperspectral imaging gives a molecular fingerprint of the native waterproofing tissues and cells with diffraction limited spatial resolution (~300 nm) at relatively high speed and without any tedious sample preparation. Lipids and lignified tissues as well as their effect on water content was directly visualized by integrating the 1299, 1600, and 3400 cm−1 band, respectively. For detailed insights into compositional changes of these polymers vertex component analysis was performed on selected sample positions. Changes have been elucidated in the composition of lignin within the lignified tissues and between interfascicular fibers and xylem vessels. Hydrophobizing changes were revealed from the epidermal layer to the cuticle as well as a change in the aromatic composition within the cuticle of trichomes. To verify Raman signatures of different waterproofing polymers additionally Raman spectra of the cuticle and cutin monomer from tomato (Solanum lycopersicum) as well as aromatic model polymers (milled wood lignin and dehydrogenation polymer of coniferyl alcohol) and phenolic acids were acquired. PMID:26973831

  6. Waterproofing in Arabidopsis: Following Phenolics and Lipids In situ by Confocal Raman Microscopy.

    PubMed

    Prats Mateu, Batirtze; Hauser, Marie Theres; Heredia, Antonio; Gierlinger, Notburga

    2016-01-01

    Waterproofing of the aerial organs of plants imposed a big evolutionary step during the colonization of the terrestrial environment. The main plant polymers responsible of water repelling are lipids and lignin, which play also important roles in the protection against biotic/abiotic stresses, regulation of flux of gases and solutes, and mechanical stability against negative pressure, among others. While the lipids, non-polymerized cuticular waxes together with the polymerized cutin, protect the outer surface, lignin is confined to the secondary cell wall within mechanical important tissues. In the present work a micro cross-section of the stem of Arabidopsis thaliana was used to track in situ the distribution of these non-carbohydrate polymers by Confocal Raman Microscopy. Raman hyperspectral imaging gives a molecular fingerprint of the native waterproofing tissues and cells with diffraction limited spatial resolution (~300 nm) at relatively high speed and without any tedious sample preparation. Lipids and lignified tissues as well as their effect on water content was directly visualized by integrating the 1299, 1600, and 3400 cm(-1) band, respectively. For detailed insights into compositional changes of these polymers vertex component analysis was performed on selected sample positions. Changes have been elucidated in the composition of lignin within the lignified tissues and between interfascicular fibers and xylem vessels. Hydrophobizing changes were revealed from the epidermal layer to the cuticle as well as a change in the aromatic composition within the cuticle of trichomes. To verify Raman signatures of different waterproofing polymers additionally Raman spectra of the cuticle and cutin monomer from tomato (Solanum lycopersicum) as well as aromatic model polymers (milled wood lignin and dehydrogenation polymer of coniferyl alcohol) and phenolic acids were acquired. PMID:26973831

  7. In situ Raman spectroscopy for growth monitoring of vertically aligned multiwall carbon nanotubes in plasma reactor

    SciTech Connect

    Labbaye, T.; Gaillard, M.; Lecas, T.; Kovacevic, E.; Boulmer-Leborgne, Ch.; Guimbretière, G.; Canizarès, A.; Raimboux, N.; Simon, P.; Ammar, M. R.; Strunskus, T.

    2014-11-24

    Portable and highly sensitive Raman setup was associated with a plasma-enhanced chemical vapor deposition reactor enabling in situ growth monitoring of multi-wall carbon nanotubes despite the combination of huge working distance, high growth speed and process temperature and reactive plasma condition. Near Edge X-ray absorption fine structure spectroscopy was used for ex situ sample analysis as a complementary method to in situ Raman spectroscopy. The results confirmed the fact that the “alternating” method developed here can accurately be used for in situ Raman monitoring under reactive plasma condition. The original analytic tool can be of great importance to monitor the characteristics of these nanostructured materials and readily define the ultimate conditions for targeted results.

  8. Advances in Raman spectroscopy for In Situ Identification of Minerals and Organics on Diverse Planetary Surfaces: from Mars to Titan

    NASA Astrophysics Data System (ADS)

    Blacksberg, J.; Alerstam, E.; Maruyama, Y.; Cochrane, C.; Rossman, G. R.

    2015-12-01

    We present recent developments in time-resolved Raman spectroscopy for in situ planetary surface exploration, aimed at identification of both minerals and organics. Raman is a non-destructive surface technique that requires no sample preparation. Raman spectra are highly material specific and can be used for identification of a wide range of unknown samples. In combination with micro-scale imaging and point mapping, Raman spectroscopy can be used to directly interrogate rocks and regolith materials, while placing compositional analyses within a microtextural context, essential for understanding surface evolutionary pathways. Due to these unique capabilities, Raman spectroscopy is of great interest for the exploration of all rocky and icy bodies, for example Mars, Venus, the Moon, Mars' moons, asteroids, comets, Europa, and Titan. In this work, we focus on overcoming one of the most difficult challenges faced in Raman spectroscopy: interference from background fluorescence of the very minerals and organics that we wish to characterize. To tackle this problem we use time-resolved Raman spectroscopy, which separates the Raman from background processes in the time domain. This same technique also enables operation in daylight without the need for light shielding. Two key components are essential for the success of this technique: a fast solid-state detector and a short-pulse laser. Our detector is a custom developed Single Photon Avalanche Diode (SPAD) array, capable of sub-ns time-gating. Our pulsed lasers are solid-state miniature pulsed microchip lasers. We discuss optimization of laser and detector parameters for our application. We then present Raman spectra of particularly challenging planetary analog samples to demonstrate the unique capabilities of this time-resolved Raman instrument, for example, Mars-analog clays and Titan-analog organics. The research described here was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a

  9. In situ laser-Raman imagery of Precambrian microscopic fossils

    PubMed Central

    Kudryavtsev, Anatoliy B.; Schopf, J. William; Agresti, David G.; Wdowiak, Thomas J.

    2001-01-01

    Laser-Raman imagery is a sensitive, noninvasive, and nondestructive technique that can be used to correlate directly chemical composition with optically discernable morphology in ancient carbonaceous fossils. By affording means to investigate the molecular makeup of specimens ranging from megascopic to microscopic, it holds promise for providing insight into aspects of organic metamorphism and biochemical evolution, and for clarifying the nature of ancient minute fossil-like objects of putative but uncertain biogenicity. PMID:11158554

  10. Dual-Remote Raman Technology for In-Situ Identification of Tank Waste - 13549

    SciTech Connect

    Bryan, Sam; Levitskaia, Tatiana; Lines, Amanda; Smith, Frannie; Josephson, Gary; Bello, Job

    2013-07-01

    A new Raman spectroscopic system for in-situ identification of the composition of solid nuclear tank waste is being developed by collaborative effort between Pacific Northwest National Laboratory (PNNL) and EIC Laboratories, Inc. The recent advancements in Raman technology allow probing the chemical composition of the tank waste without sample collection. In the newly tested configuration, the Raman probe is installed on the top of the tank riser and sends the incident laser beam to the bottom of the tank, 10 - 70 feet away. The returning light containing chemical information is collected by the Raman probe and is transmitted via fiber optic cable to the spectrometer located outside the tank farm area. This dual remote technology significantly expands currently limited options for the safe rapid in-situ identification of the solid tank waste needed for the retrieval decisions. The developed Raman system was extensively tested for acceptability prior to tank farm deployment. This testing included calibration of the system with respect of the distance between the Raman probe and the sample, incident laser beam angle, and presence of the optical interferences. The Raman system was successfully deployed on Tank C-111 at the US DOE Hanford site. As the result of this deployment, the composition of the hardpan at the bottom of C-111 tank was identified. Further development of the dual-remote Raman technology will provide a significant safety enhancement eliminating the potential of personnel radiation exposure associated with the grab sample collection and expands options of the rapid and cost-effective in-situ chemical analysis of the tank waste. (authors)

  11. Dual-Remote Raman Technology for In-Situ Identification of Tank Waste

    SciTech Connect

    Bryan, Samuel A.; Levitskaia, Tatiana G.; Lines, Amanda M.; Smith, Frances N.; Josephson, Gary B.; Bello, Job M.

    2013-02-24

    A new Raman spectroscopic system for in-situ identification of the composition of the solid nuclear tank waste is being developed by collaborative effort between Pacific Northwest National Laboratory (PNNL) and EIC, Inc. The recent advancements in the Raman technology allow probing the chemical composition of the tank waste without sample collection. In the newly tested configuration, the Raman probe is installed on the top of the tank riser and sends the incident laser beam to the bottom of the tank, 10 – 70 feet away. The returning light containing chemical information is collected by the Raman probe and transmits it via fiber optic cable to the spectrometer located outside the tank farm area. This dual remote technology significantly expands currently limited options for the safe rapid in-situ identification of the solid tank waste needed for the retrieval decisions. The developed Raman system was extensively tested for acceptability prior tank farm deployment. This testing included calibration of the system with the respect of the distance between the Raman probe and the sample, incident laser beam angle, and presence of the optical interferences. The Raman system was successfully deployed to C-111 tank at the US DOE Hanford site. As the result of this deployment, the composition of the hardpan at the bottom of C-111 tank was identified. Further development of the dual-remote Raman technology will provide a significant safety enhancement eliminating the potential of personnel radiation exposure associated with the grab sample collection and expands options of the rapid and cost-effective in-situ chemical analysis of the tank waste.

  12. In situ polarized micro-Raman investigation of periodic structures realized in liquid-crystalline composite materials.

    PubMed

    Castriota, Marco; Fasanella, Angela; Cazzanelli, Enzo; De Sio, Luciano; Caputo, Roberto; Umeton, Cesare

    2011-05-23

    In situ polarized micro-Raman Spectroscopy has been utilized to determine the liquid crystal configuration inside a periodic liquid crystalline composite structure made of polymer slices alternated to films of liquid crystal. Liquid crystal, Norland Optical Adhesive (NOA-61) monomer and its polymerized form have been investigated separately. The main Raman features, used as markers for the molecular orientation estimation, have been identified. In situ polarized Raman spectra indicate that the orientation of the liquid crystal director inside the structure is perpendicular to its polymeric slices. Results show the usefulness of in situ polarized micro-Raman spectroscopy to investigate liquid crystalline composite structures. PMID:21643304

  13. A new instrument adapted to in situ Raman analysis of objects of art.

    PubMed

    Vandenabeele, P; Weis, T L; Grant, E R; Moens, L J

    2004-05-01

    The analysis of precious artefacts and antiquities demands care in order to minimise the risk of accidental damage during measurement. Mobile fibre-optic-based Raman instruments offer a means to avoid destructive sampling and eliminate the need to transport artefacts for spectrochemical analysis. In this work we present a new mobile instrument developed and optimised for the in situ Raman investigation of objects of art and antiquities. The instrument is controlled by a portable computer. Selected mounts cover many types of artefacts. Newly written software routines organise spectra together with measurement parameters and facilitate calibration of the instrument. The present paper describes this new Raman instrument and discusses some challenges in the transition from a laboratory environment to in situ investigations in museums. PMID:15045464

  14. In-situ histochemical analysis of human coronary artery by Raman spectroscopy compared with biochemical assay

    NASA Astrophysics Data System (ADS)

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

    1995-05-01

    We have developed a method to analyze quantitatively the biochemical composition of human coronary artery in situ using near infrared Raman spectroscopy. Human coronary arteries were obtained from explanted hearts after heart transplantation. Samples of normal intima/media, adventitia, non-calcified and calcified plaque were illuminated with 830 nm light from a CW Ti:Sapphire laser. The Raman scattered light was collected and coupled into a 1/4 meter spectrometer that dispersed the light onto a liquid nitrogen cooled, deep-depletion CCD detector. Raman spectra with sufficiently high S/N for extracting biochemical information could be collected in under one second. The spectra were analyzed using a recently developed model to quantitate the relative weight fractions of cholesterol, cholesterol esters, triacylglycerol, phospholipids, protein, and calcium salts. After spectral examination, the artery samples were biochemically assayed to determine the total lipid weight and the amount of the major lipid categories as a percentage of the total lipid content. The results of the lipid biochemical assay and the Raman spectral model compare favorably, indicating that relative lipid weights can be accurately determined in situ. Protein and calcium salts assays are underway. This in situ biochemical information may be useful in diagnosing atherosclerosis and studying disease progression.

  15. 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.

  16. In situ Raman monitoring of single-walled carbon nanotube filling with copper chloride

    NASA Astrophysics Data System (ADS)

    Eremin, Timofei V.; Tonkikh, Alexander A.; Kudryashova, Ekaterina M.

    2016-03-01

    In situ characterization of single-walled carbon nanotubes during their gas-phase filling with copper chloride (CuCl) was performed with Raman spectroscopy. The time dependence of positions and intensities of G, 2D, and radial breathing modes was investigated. It was demonstrated that the adsorption of copper chloride from gas phase on the external and internal surfaces of nanotubes leads to the Raman mode shifting. However, this effect is weaker than in case of formation of one-dimensional CuCl crystals inside nanotubes.

  17. Fiber optic Raman spectrograph for in situ environmental monitoring. Final report

    SciTech Connect

    Carrabba, M.M.

    1992-11-01

    This report discusses the development and testing of a small laboratory prototype, field Raman spectrometer which can be used with a fiber optic sampling probe incorporting substrates tailored for surface enhanced Raman spectroscopy (SERS) for low level detection of chemical species. The report also discusses demonstration of apparatus for both laboratory and field environmental samples typical of DOE environmental restoration sites. Preliminary results establish a new technique which can be used in,the field to identify and profile in situ a wide variety of pollutants at the action levels required for remediation.

  18. First steps of in situ surface-enhanced Raman scattering during shipboard experiments.

    PubMed

    Péron, Olivier; Rinnert, Emmanuel; Colas, Florent; Lehaitre, Michel; Compère, Chantal

    2010-10-01

    It is shown that the surface-enhanced Raman scattering (SERS) technique can be applied to detect organic molecules during in situ experiments. To this purpose, we used trans-1,2-bis(4-pyridyl)ethylene (BPE) as a target molecule. Adsorbed on the SERS chemosensor surface and excited under laser, the vibration modes of the molecules can be identified. SERS chemosensors are based on quartz substrates functionalized by silanization and partially coated with gold nanoparticles. SERS measurements during shipboard experiments were made with a home-made in situ Raman spectrometer connected to a marinized micro-fluidic system. The device was designed to host chemosensors in order to ensure measurements with a flow cell. A theoretical limit of detection was estimated in the range of picomolar (pM) concentrations based on Freundlich isotherm calculations. PMID:20925977

  19. Metallic monoclinic phase in VO2 induced by electrochemical gating: In situ Raman study

    NASA Astrophysics Data System (ADS)

    Nath Gupta, Satyendra; Pal, Anand; Muthu, D. V. S.; Kumar, P. S. Anil; Sood, A. K.

    2016-07-01

    We report in situ Raman scattering studies of electrochemically top gated VO2 thin film to address metal-insulator transition (MIT) under gating. The room temperature monoclinic insulating phase goes to metallic state at a gate voltage of 2.6 V. However, the number of Raman modes do not change with electrolyte gating showing that the metallic phase is still monoclinic. The high-frequency Raman mode A g (7) near 616 cm‑1 ascribed to V-O vibration of bond length 2.06 Å in VO6 octahedra hardens with increasing gate voltage and the B g (3) mode near 654 cm‑1 softens. This shows that the distortion of the VO6 octahedra in the monoclinic phase decreases with gating. The time-dependent Raman data at fixed gate voltages of 1 V (for 50 minutes, showing enhancement of conductivity by a factor of 50) and 2 V (for 130 minutes, showing further increase in conductivity by a factor of 5) show similar changes in high-frequency Raman modes A g (7) and B g (3) as observed in gating. This slow change in conductance together with Raman frequency changes show that the governing mechanism for metalization is more likely due to the diffusion-controlled oxygen vacancy formation due to the applied electric field.

  20. Infrared and Raman Imaging of Heterogeneous Catalysts

    SciTech Connect

    E Stavistki; B Weckhuysen

    2011-12-31

    The miniaturization of in situ spectroscopic tools has been recognized as a forefront instrumental development for the characterization of heterogeneous catalysts. With the multitude of micro-spectroscopic methods available fundamental insight into the structure-function relationships of catalytic processes can be obtained. Among these techniques vibrational spectroscopy is one of the most versatile methods and capable to shed insight into the molecular structure of reaction intermediates and products, the chemical state of catalyst materials during reaction as well as the nature of interactions between reactants/intermediates/products and the catalyst surface. In this tutorial review we discuss the recent developments in the field of infrared (IR) and Raman micro-spectroscopy and illustrate their potential. Showcase examples include (1) chemical imaging of spatial heterogeneities during catalyst preparation, (2) high-throughput catalyst screening, (3) transport and adsorption phenomena within catalytic solids and (4) reactivity studies of porous oxides, such as zeolites. Finally, new in situ spectroscopy tools based on vibrational spectroscopy and their potential in the catalysis domain are discussed.

  1. In situ electron spin resonance and Raman spectroscopic studies of the electrochemical process of conducting polypyrrole films

    SciTech Connect

    Zhong, C.J.; Tian, Z.Q.; Tian, Z.W. )

    1990-03-08

    The electrochemical redox properties of conducting polypyrrole (PPy) films coated on electrodes are investigated in aqueous solutions by use of the in situ techniques of electron spin resonance (ESR) and Raman spectroscopy. Comparisons between the experimental in situ ESR data and a theoretical kinetic prediction on the basis of the polaron-bipolaron model are presented.

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

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

    2012-09-01

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

  3. Microsystem technology based diode lasers and Raman sensors for in situ food quality control

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    A microsystem based Raman sensor system for the in situ control of meat was realized. As excitation laser source a compact external cavity diode laser (ECDL) emitting at 671.0 nm mounted on a micro optical bench with a total dimension of (13 x 4 x 1) mm3 is implemented. An output power of 200 mW, a stable emission at 671.0 nm, and a narrow spectral width of about 80 pm, i.e. 2 cm-1, were measured. The device is well suited for Raman measurements of liquid and solid samples. The devices parameters and the stability will be reviewed. The micro-system laser device is implemented into a specifically laboratory prototype, including an optical bench with a diameter of 25 mm and a length of 170 mm. The probe is coupled fiber-optically to a polychromator with CCD detector for rapid spectral analysis. The Raman probe is characterized and first Raman measurements of porcine musculus longissimus dorsi through the package will be presented. The usefulness of Raman spectroscopy will be discussed with a view of integrating the sensor in a handheld laser scanner for food control.

  4. 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.

  5. In-SITU Raman Spectroscopy of Single Microparticle Li-Intercalation Electrodes

    NASA Technical Reports Server (NTRS)

    Dokko, Kaoru; Shi, Qing-Fang; Stefan, Ionel C.; Scherson, Daniel A.

    2003-01-01

    Modifications in the vibrational properties of a single microparticle of LiMn2O4 induced by extraction and subsequent injection of Li(+) into the lattice have been monitored in situ via simultaneous acquisition of Raman scattering spectra and cyclic voltammetry data in 1M LiC1O4 solutions in ethylene carbonate (EC):diethyl carbonate (DEC) mixtures (1:1 by volume). Statistical analyses of the spectra in the range 15 < SOD < 45%, where SOD represents the state of discharge (in percent) of the nominally fully charged material, i.e. lambda-MnO2, were found to be consistent with the coexistence of two distinct phases of lithiated metal oxide in agreement with information derived from in situ X-ray diffraction (XRD) measurements involving more conventional battery-type electrodes.

  6. Microparticle electrodes and single particle microbatteries: electrochemical and in situ microRaman spectroscopic studies.

    PubMed

    Jebaraj, Adriel Jebin Jacob; Scherson, Daniel A

    2013-05-21

    Studies of the intrinsic electrochemical, structural, and electronic propertiesof microparticles of energy storage materials can provide much needed insight into the factors that control various aspects of the performance of technical electrodes for battery applications. This Account summarizes efforts made in our laboratories toward the development and implementation of methods for the in situ electrical, optical, and spectroscopic characterization of microparticles of a variety of such materials, including Ni hydroxide, Zn, carbon, and lithiated Mn and Co oxides. In the case of Ni hydroxide, the much darker appearance of NiOOH compared to the virtually translucent character of virgin Ni(OH)2 allowed for the spatial and temporal evolution of charge flow within spherical microparticles of Ni(OH)2 to be monitored in real time during the first scan toward positive potentials using computer-controlled video imaging. In situ Raman scattering measurements involving single microparticles of Zn harvested from a commercial Zn|MnO2 battery revealed that passive films formed in strongly alkaline solutions by stepping the potential from 1.55 V to either 0.7 or 0.8 V vs SCE displayed a largely enhanced feature at ca. 565 cm(-1) ascribed to a longitudinal optical phonon mode of ZnO, an effect associated with the presence of interstitial Zn and oxygen deficiencies in the lattice. In addition, significant amounts of crystalline ZnO could be detected only for passive films formed at the same two potentials after the electrodes had been roughened by a single passivation-reduction step. Quantitative correlations were found in the case of LiMn2O4 and KS-44 graphite between the Raman spectral properties and the state of charge. In the case of KS-44, a chemometrics analysis of the spectroscopic data in the potential region in which the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur made it possible to determine independently the fraction of each

  7. In situ monitoring of biomolecular processes in living systems using surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Altunbek, Mine; Kelestemur, Seda; Culha, Mustafa

    2015-12-01

    Surface-enhanced Raman scattering (SERS) continues to strive to gather molecular level information from dynamic biological systems. It is our ongoing effort to utilize the technique for understanding of the biomolecular processes in living systems such as eukaryotic and prokaryotic cells. In this study, the technique is investigated to identify cell death mechanisms in 2D and 3D in vitro cell culture models, which is a very important process in tissue engineering and pharmaceutical applications. Second, in situ biofilm formation monitoring is investigated to understand how microorganisms respond to the environmental stimuli, which inferred information can be used to interfere with biofilm formation and fight against their pathogenic activity.

  8. In Situ Planetary Mineralogy Using Simultaneous Time Resolved Fluorescence and Raman Spectroscopy

    NASA Technical Reports Server (NTRS)

    Blacksberg, J.; Rossman , G.R.

    2011-01-01

    Micro-Raman spectroscopy is one of the primary methods of mineralogical analysis in the laboratory, and more recently in the field. Because of its versatility and ability to interrogate rocks in their natural form it is one of the front runners for the next generation of in situ instruments designed to explore adverse set of solar system bodies (e.g. Mars, Venus, the Moon, and other primitive bodies such as asteroids and the Martian moons Phobos and Deimos), as well as for pre-selection of rock and soil samples for potential cache and return missions.

  9. In situ Raman estimation of irradiation-induced heating of UO2

    NASA Astrophysics Data System (ADS)

    Guimbretière, G.; Canizarès, A.; Desgranges, L.; Caraballo, R.; Duval, F.; Jegou, C.; Magnin, M.; Simon, P.

    2016-09-01

    We present an in situ Raman estimation of the temperature increase of UO2 pellets induced by cyclotron He2+ ionic irradiation in different environments (Ar gas or water): For instance, in the Ar gas environment, the sample is heated to a temperature 150-200 °C (i.e., below the annealing temperature of UO2 defects). For water, the sample is heated from 30 to 80 °C, just below the range of the studtite/metastudtite and the schoepite/metaschoepite transitions.

  10. Combined synchrotron XRD/Raman measurements: in situ identification of polymorphic transitions during crystallization processes.

    PubMed

    Klimakow, Maria; Leiterer, Jork; Kneipp, Janina; Rössler, Ernst; Panne, Ulrich; Rademann, Klaus; Emmerling, Franziska

    2010-07-01

    A combination of two analytical methods, time-resolved X-ray diffraction (XRD) and Raman spectroscopy, is presented as a novel tool for crystallization studies. An acoustic levitator was employed as sample environment. This setup enables the acquisition of XRD and Raman data in situ simultaneously within a 20 s period and hence permits investigation of polymorphic phase transitions during the crystallization process in different solvents (methanol, ethanol, acetone, dichloromethane, acetonitrile). These real time measurements allow the determination of the phase content from the onset of the first crystalline molecular assemblies to the stable system. To evaluate the capability of this approach, the setup was applied to elucidate the crystallization process of the polymorphic compound nifedipine. The results indicate the existence of solvent-dependent transient phases during the crystallization process. The quality of the data allowed the assignment of the lattice constants of the hitherto unknown crystal structure of the beta-polymorph. PMID:20222693

  11. High pressure optical cell for synthesis and in situ Raman spectroscopy of hydrogen clathrate hydrates

    NASA Astrophysics Data System (ADS)

    Celli, Milva; Zoppi, Marco; Zaghloul, Mohamed A. S.; Ulivi, Lorenzo

    2012-11-01

    We report the design, realization, and test of a high-pressure optical cell that we have used to measure the Raman spectra of hydrogen clathrate hydrates, synthesized in situ by the application of 200-300 MPa of gas pressure on solid water. The optical apparatus is mounted on a cryogenic system so to allow measurements and sample treatment at any temperature between 300 and 20 K. A capillary pipe is connected to the inside of the cell to allow the gas flow into and out of the cell, and to regulate the internal pressure at any value from 0 to 300 MPa. In the experimental test described in this paper, the cell has been partly filled, at room temperature, with a small amount of water, then frozen at 263 K before injecting hydrogen gas, at pressure of 150 MPa, into the cell. This procedure has permitted to study hydrogen clathrate formation, by measuring Raman spectra as a function of time.

  12. In situ laser Raman spectra of iron phthalocyanine adsorbed on copper and gold electrodes. [Electronic structure

    SciTech Connect

    Melendres, C.A.; Rios, C.B.; Feng, X.; McMasters, R.

    1983-01-01

    Raman spectra of iron phthalocyanine (FePc) and its tetrasulfonated derivative (FeTSPc) adsorbed on copper and gold electrodes have been observed in situ in 0.05 M H/sub 2/SO/sub 4/ solution. Results confirm the authors previous finding on the coordination of FePc to water molecules to solution. Evidence suggests that the iron phthalocyanines are probably oriented with their planes parallel to the electrode surface even in immersed electrodes. A decrease in intensity and broadening of some vibrational bands are observed on increasing cathodic polarization; these are attributed to a lifting of the degeneracy of the vibrational modes due to a change in symmetry of the adsorbed molecules brought about by polarization induced by the double-layer field. The effect of carbon on the Raman spectra is discussed. The iron phthalocyanines appear to be stable at potentials close to hydrogen evolution in the absence of oxygen. 18 references, 8 figures.

  13. In situ laser Raman spectra of iron phthalocyanine adsorbed on copper and gold electrodes

    SciTech Connect

    Melendres, C.A.; Rios, C.B.; Feng, X.; McMasters, R.

    1983-09-01

    Raman spectra of iron phthalocyanine (FePc) and its tetrasulfonated derivative (FeTSPc) adsorbed on copper and gold electrodes have been observed in situ in 0.05 M H/sub 2/SO/sub 4/ solution. Results confirm our previous finding on the coordination of FePc to water molecules to solution. Evidence suggests that the iron phthalocyanines are probably oriented with their planes parallel to the electrode surface even in immersed electrodes. A decrease in intensity and broadening of some vibrational bands are observed on increasing cathodic polarization; these are attributed to a lifting of the degeneracy of the vibrational modes due to a change in symmetry of the adsorbed molecules brought about by polarization induced by the double-layer field. The effect of carbon on the Raman spectra is discussed. The iron phthalocyanines appear to be stable at potentials close to hydrogen evolution in the absence of oxygen. 8 figures.

  14. 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

  15. 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

  16. In Situ Raman Microscopy of a Single Graphite Microflake Electrode in a Li(+)-containing Electrolyte

    NASA Technical Reports Server (NTRS)

    Shi, Qing-Fang; Dokko, Kaoru; Scherson, Daniel A.

    2003-01-01

    Highly detailed Raman spectra from a single KS-44 graphite microflake electrode as a function of the applied potential have been collected in situ using a Raman microscope and a sealed spectroelectrochemical cell isolated from the laboratory environment. Correlations were found between the Raman spectral features and the various Li(+) intercalation stages while recording in real time Raman spectra during a linear potential scan from 0.7 down ca. 0.0V vs Li/Li(+) at a rate of 0.1 mV/s in a 1M LiClO4 solution in a 1:l (by volume) ethylene carbonate (EC):diethyl carbonate (DEC) mixture. In particular, clearly defined isosbestic points were observed for data collected in the potential range where the transition between dilute phase 1 and phase 4 of lithiated graphite is known to occur, i.e. 0.157 < E < 0.215 vs Li/Li(+). Statistical analysis of the spectroscopic data within this region made it possible to determine independently the fraction of each of the two phases present as a function of potential without relying on coulometric information and then predict, based on the proposed stoichiometry for the transition, a spectrally-derived voltammetric feature.

  17. 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.

  18. Thermo-Raman spectroscopy in situ monitoring study of solid-state synthesis of NiO-Al{sub 2}O{sub 3} nanoparticles and its characterization

    SciTech Connect

    Ghule, Anil Vithal; Ghule, Kalyani; Tzing, S.-H.; Punde, Tushar H.; Chang Hua; Ling, Y.C.

    2009-12-15

    Hyphenation of thermogravimetric analyzer (TGA) and thermo-Raman spectrophotometer for in situ monitoring of solid-state reaction in oxygen atmosphere forming NiO-Al{sub 2}O{sub 3} catalyst nanoparticles is investigated. In situ thermo-Raman spectra in the range from 200 to 1400 cm{sup -1} were recorded at every degree interval from 25 to 800 deg. C. Thermo-Raman spectroscopic studies reveal that, although the onset of formation is around 600 deg. C, the bulk NiAl{sub 2}O{sub 4} forms at temperatures above 800 deg. C. The X-ray diffraction (XRD) spectra and the scanning electron microscopy (SEM) images of the reaction mixtures were recorded at regular temperature intervals of 100 deg. C, in the temperature range from 400 to 1000 deg. C, which could provide information on structural and morphological evolution of NiO-Al{sub 2}O{sub 3}. Slow controlled heating of the sample enabled better control over morphology and particle size distribution ({approx}20-30 nm diameter). The observed results were supported by complementary characterizations using TGA, XRD, SEM, transmission electron microscopy, and energy dispersive X-ray analysis. - Graphical abstract: Hyphenation of thermogravimetric analyzer and thermo-Raman spectrophotometer for in situ monitoring of solid-state reaction at controlled heating rate and in oxygen atmosphere forming NiO-Al{sub 2}O{sub 3} catalyst nanoparticles is investigated.

  19. Confocal Raman microscopy and fluorescent in situ hybridization - A complementary approach for biofilm analysis.

    PubMed

    Kniggendorf, Ann-Kathrin; Nogueira, Regina; Kelb, Christian; Schadzek, Patrik; Meinhardt-Wollweber, Merve; Ngezahayo, Anaclet; Roth, Bernhard

    2016-10-01

    We combine confocal Raman microscopy (CRM) of wet samples with subsequent Fluorescent in situ hybridization (FISH) without significant limitations to either technique for analyzing the same sample of a microbial community on a cell-to-cell basis. This combination of techniques allows a much deeper, more complete understanding of complex environmental samples than provided by either technique alone. The minimalistic approach is based on laboratory glassware with micro-engravings for reproducible localization of the sample at cell scale combined with a fixation and de- and rehydration protocol for the respective techniques. As proof of concept, we analyzed a floc of nitrifying activated sludge, demonstrating that the sample can be tracked with cell-scale precision over different measurements and instruments. The collected information includes the microbial content, spatial shape, variant chemical compositions of the floc matrix and the mineral microparticles embedded within. In addition, the direct comparison of CRM and FISH revealed a difference in reported cell size due to the different cell components targeted by the respective technique. To the best of our knowledge, this is the first report of a direct cell-to-cell comparison of confocal Raman microscopy and Fluorescent in situ hybridization analysis performed on the same sample. An adaptation of the method to include native samples as a starting point is planned for the near future. The micro-engraving approach itself also opens up the possibility of combining other, functionally incompatible techniques as required for further in-depth investigations of low-volume samples. PMID:27423128

  20. Development of a Laser Raman Spectrometer for In Situ Measurements in the Deep Ocean

    NASA Astrophysics Data System (ADS)

    White, S. N.; Brewer, P. G.; Peltzer, E. T.; Malby, G. E.; Pasteris, J. D.

    2002-12-01

    We have developed an ROV-deployable laser Raman spectrometer (LRS) to make in situ measurements of solid, liquid and gaseous species in the ocean (up to 3600 m depth). The LRS can be used to determine chemical and structural composition by irradiating the target with a laser and measuring the inelastically scattered (Raman shifted) light. The frequency shift from the exciting wavelength is due to characteristic molecular vibrations of the molecule; thus, the Raman spectrum serves as a fingerprint of a substance based on molecular composition and crystal structure. Raman spectroscopy is rapid, and typically requires no sample preparation. However, the weak Raman effect (~1 in 108 photons), the need for precise laser positioning, and fluorescence, pose challenges. We have acquired an LRS from Kaiser Optical Systems, Inc. and adapted it for use in the ocean by dividing the components into three pressure cases, building penetrating fiber optic cables, developing an Ethernet interface to control the system from shipboard, and redesigning and rebuilding non-robust components. Future improvements will include weight/size reduction, adding through-the-lens visualization, and using liquid core optical waveguides to increase sensitivity. An increase in sensitivity of x10 would permit direct observation of natural seawater HCO3 and CO3 peaks. The LRS has been successfully deployed over 6 times on MBARI's two remotely operated vehicles in 2002. Initial measurements of standards (e.g., isopropanol, calcite, and diamond) at depths as great as 3600 m have proven the effectiveness of the instrument in the deep ocean and have allowed us to advance methods for its use. Detailed spectra of seawater in situ and in the lab have also been obtained to better understand the ever-present seawater background (which includes water and SO4 peaks, and very little fluorescence). We have used the LRS in a number of deep-sea CO2 sequestration studies to acquire spectra of gaseous CO2 and CO2/N2

  1. In situ Raman study of Electrochemically Intercalted Bisulfate Ions in Carbon Nanotube Bundles

    NASA Astrophysics Data System (ADS)

    Sumanasekera, G. U.; Allen, J. L.; Rao, A. M.; Fang, S. L.; Eklund, P. C.

    1998-03-01

    We have investigated the electrochemical intercalation of bisulfate ions in single-walled carbon nanotubes (SWNT) using in situ Raman spectroscopy. SWNTs pressed onto a Pt plate was used as the working electrode, a Pt wire and Ag/AgCl were used, respectively, as the counter electrode and reference electrode. Sulfuric acid (95%) was used as the electrolyte. Using Raman scattering we have observed an apparent rapid spontaneous reaction involving charge transfer between ionically bonded HSO_4^- anions and the nanotubes. This is evidenced by an instantaneous shift of the Raman-active tangential mode frequency from 1593 cm -1 to 1604 cm-1 (It was not possible to reverse this shift electrochemically to 1593 cm-1, even at the expense of large reverse bias). In forward bias, after this initial instantaneous reaction, the tangential mode frequency again upshifted from 1604 cm-1 to 1614 cm-1 linearly with external electrochemical charge Q. From the slope of ω(Q) we found in this regime, δω/δ f= 1220 cm-1 (f = holes/carbon). Upon further charging, a second regime with slope δω/δ f = 118 cm-1 was observed where the frequency upshifted from 1614 cm-1 to 1620 cm-1. The results are compared to similar studies in C_p^+HSO_4^-.xH_2SO4 graphite intercalation compounds.

  2. A remote scanning Raman spectrometer for in situ measurements of works of art.

    PubMed

    Brambilla, Alex; Osticioli, Iacopo; Nevin, Austin; Comelli, Daniela; D'Andrea, Cosimo; Lofrumento, Cristiana; Valentini, Gianluca; Cubeddu, Rinaldo

    2011-06-01

    In conservation science, one of the main concerns is to extract information from an artistic surface without damaging it. Raman spectroscopy has emerged in recent years as a reliable tool for the non-destructive analysis of a wide range of inorganic and organic materials in works of art and archaeological objects. Nevertheless, the technique is still mainly limited to the analysis of micro-samples taken from artistic surfaces. The development of an instrument able to perform non-contact analysis of an area of a few square centimeters aims to further increase the employment of this technique. This paper describes the development of a prototype Raman scanning spectrometer based on a diode laser, a 2D scanning mirror stage and a custom optical system, which can map a surface of 6 cm in diameter at a working distance of 20 cm. The device exhibits collecting optics with a depth of field close to 6 cm, which makes the Raman system suitable for the analysis of non-flat surfaces and three-dimensional objects. In addition, the overall dimensions and weight of the instrument have been limited in order to make the device transportable and, in principle, usable for in situ measurements. Details on the design of the device, with particular emphasis on the collecting optical system, and on results of the characterization tests carried out to assess its performances are reported. Finally, an example of an application involving the identification of pigments from a model painting is presented. PMID:21721676

  3. Raman spectroscopy for in situ- evaluation of high-grade malignant gliomas induced in SCID mice

    NASA Astrophysics Data System (ADS)

    Clary, Candace E.; Dergachev, Alex Y.; Mirov, Sergey B.; Gillespie, G. Yancey

    1997-05-01

    Each year, more people at younger ages are diagnosed with primary brain tumors. Current histological discrimination between normal and diseased tissue occurs after tissue excision. A reliable optical biopsy for open craniotomy would optimize the amount and types of tissue removal by making an accurate evaluation before excision. The presented work is part of a study investigating the clinical diagnostic potential of Raman spectroscopy for gliomas. It has been shown that the optical properties of in vitro tissue are strongly dependent upon sample preparation. The investigation of the effects of time latency, paraformalin tissue fixation, and tissue perfusion with carbogen-bubbled cortical transport solution on their respective Raman spectra of brain tissue and tumors will be discussed, as well as their implications on the study of neurological tissue. The studies are conducted with in situ tissue samples from scid mice and 785 nm pulsed alexandrite laser excitation. Results illustrating positive qualitative and quantitative variations between Raman spectra of normal and malignant brain tissue will be presented.

  4. Characterization of chemical doping of graphene by in-situ Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Kim, S. J.; Park, S. J.; Kim, H. Y.; Jang, G. S.; Park, D. J.; Park, Ji-Yong; Lee, Soonil; Ahn, Y. H.

    2016-05-01

    We explored single-layer graphene and graphene field-effect transistors immersed in nitric acid using in-situ Raman spectroscopy. Two distinct stages were observed in the chemical doping process. The first stage involved blue shifts of the G and 2D peaks, whose saturation occurred rapidly with a time constant in the range of 10-25 s depending on the molar concentration of the acid. In the second stage, the intensity of the D peak, which was associated with structural defect formation, increased for a relatively long period of time. Since the major doping effects appeared during the first stage, the optimal doping conditions under which no noticeable structural defect formation occurred can be determined by monitoring the frequency shift. Transient doping concentrations along with structural defect densities were obtained from the Raman peak positions and intensities. We found that the doping-induced shift in the Dirac point in graphene field-effect transistors exhibited a fast response with respect to frequency shifts in the Raman spectra, which was attributed to the saturation of electrostatic gating effects.

  5. 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

  6. A Nanoplasmonic Strategy for Precision in-situ Measurements of Tip-enhanced Raman and Fluorescence Spectroscopy.

    PubMed

    Meng, Lingyan; Sun, Mengtao; Chen, Jianing; Yang, Zhilin

    2016-01-01

    We theoretically investigate an optimized tip-film system that supports in-situ measurement of tip-enhanced Raman spectroscopy (TERS) and tip-enhanced fluorescence (TEF) of dye molecules. A scanning tunneling microscope (STM) is proposed to precisely control the tip-film distance, and thus in-situ measurement of TERS and TEF can be realized utilizing the specific surface plasmon resonance (SPR) properties of the tip-film system. Our calculations show that the optimized tip-film distance of 2 nm suggests a possibility of efficient acquisition of TERS and TEF in-situ. The calculated spatial resolution of TERS and spectral resolution of TEF can be down to 6.5 nm and 10 nm, respectively. Our theoretical results may find promising application in developing multiple functional nano-spectroscopy through which Raman and fluorescence can be measured in-situ at the nanoscale level. PMID:26780882

  7. A Nanoplasmonic Strategy for Precision in-situ Measurements of Tip-enhanced Raman and Fluorescence Spectroscopy

    NASA Astrophysics Data System (ADS)

    Meng, Lingyan; Sun, Mengtao; Chen, Jianing; Yang, Zhilin

    2016-01-01

    We theoretically investigate an optimized tip-film system that supports in-situ measurement of tip-enhanced Raman spectroscopy (TERS) and tip-enhanced fluorescence (TEF) of dye molecules. A scanning tunneling microscope (STM) is proposed to precisely control the tip-film distance, and thus in-situ measurement of TERS and TEF can be realized utilizing the specific surface plasmon resonance (SPR) properties of the tip-film system. Our calculations show that the optimized tip-film distance of 2 nm suggests a possibility of efficient acquisition of TERS and TEF in-situ. The calculated spatial resolution of TERS and spectral resolution of TEF can be down to 6.5 nm and 10 nm, respectively. Our theoretical results may find promising application in developing multiple functional nano-spectroscopy through which Raman and fluorescence can be measured in-situ at the nanoscale level.

  8. A Nanoplasmonic Strategy for Precision in-situ Measurements of Tip-enhanced Raman and Fluorescence Spectroscopy

    PubMed Central

    Meng, Lingyan; Sun, Mengtao; Chen, Jianing; Yang, Zhilin

    2016-01-01

    We theoretically investigate an optimized tip-film system that supports in-situ measurement of tip-enhanced Raman spectroscopy (TERS) and tip-enhanced fluorescence (TEF) of dye molecules. A scanning tunneling microscope (STM) is proposed to precisely control the tip-film distance, and thus in-situ measurement of TERS and TEF can be realized utilizing the specific surface plasmon resonance (SPR) properties of the tip-film system. Our calculations show that the optimized tip-film distance of 2 nm suggests a possibility of efficient acquisition of TERS and TEF in-situ. The calculated spatial resolution of TERS and spectral resolution of TEF can be down to 6.5 nm and 10 nm, respectively. Our theoretical results may find promising application in developing multiple functional nano-spectroscopy through which Raman and fluorescence can be measured in-situ at the nanoscale level. PMID:26780882

  9. In situ surface-enhanced Raman scattering spectroelectrochemistry of oxygen species.

    PubMed

    Itoh, Takashi; Maeda, Toshiteru; Kasuya, Atsuo

    2006-01-01

    In situ surface-enhanced Raman scattering (SERS) combined with electrochemical analysis is applied to the determination of oxygen species on silver electrodes in alkaline hydroxide aqueous solution at room temperature and gold electrodes in carbonate melts at high temperature. This technique, referred to as SERS spectroelectrochemistry, reveals Raman spectral lines in the 500-1100 cm(-1) range under electrode potential scanning, assignable to superoxide ions (O2-) and peroxide ions (O2(2-)) on the electrode surface. These lines for oxygen molecule species have potential dependence with changing potential. In the alkaline hydroxide aqueous solution, the Raman peaks due to oxygen molecules are observed at potentials between 0.2 V and -0.8 V (vs. Ag/AgCl) only in the cathodic scan. This irreversible behavior in cyclic voltammograms indicates the existence of an intermediate stage in the oxygen reduction process, in which oxygen is released from the AgO films on the electrode at potentials corresponding to the onset of the last current peak in the voltammogram. This liberated oxygen molecule remains in solution at the interface until hydroxyls or water molecules are formed when the potential reaches the potential zero charge (PZC). In the high-temperature carbonate melts, Raman lines at 1047, 1080, and 800 cm(-1) are apparent for the eutectic (62 + 38) mol% (Li + K)CO3 melt at 923 K, and at 735 cm(-1) for the Li2CO3 melt at 1123 K. These results suggest that oxygen reduction in the Li2CO3 melt involves only peroxide ions, while that in (62 + 38) mol% (Li + K)CO3 involves both peroxide and superoxide ions at the three-phase boundary interface. PMID:16833110

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

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Kronfeldt, Heinz-Detlef

    2012-05-01

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

  11. Portable Sequentially Shifted Excitation Raman spectroscopy as an innovative tool for in situ chemical interrogation of painted surfaces.

    PubMed

    Conti, Claudia; Botteon, Alessandra; Bertasa, Moira; Colombo, Chiara; Realini, Marco; Sali, Diego

    2016-08-01

    We present the first validation and application of portable Sequentially Shifted Excitation (SSE) Raman spectroscopy for the survey of painted layers in art. The method enables the acquisition of shifted Raman spectra and the recovery of the spectral data through the application of a suitable reconstruction algorithm. The technique has a great potentiality in art where commonly a strong fluorescence obscures the Raman signal of the target, especially when conventional portable Raman spectrometers are used for in situ analyses. Firstly, the analytical capability of portable SSE Raman spectroscopy is critically discussed using reference materials and laboratory specimens, comparing its results with other conventional high performance laboratory instruments (benchtop FT-Raman and dispersive Raman spectrometers with an external fiber optic probe); secondly, it is applied directly in situ to study the complex polychromy of Italian prestigious terracotta sculptures of the 16(th) century. Portable SSE Raman spectroscopy represents a new investigation modality in art, expanding the portfolio of non-invasive, chemically specific analytical tools. PMID:27273377

  12. Raman and FTIR imaging of dynamic polymer systems

    NASA Astrophysics Data System (ADS)

    Bobiak, John Peter

    This work aims to expand the applications of Raman and infrared imaging in materials science and engineering. Recent developments in spectroscopic imaging technology have led to relatively fast image acquisition rates, enabling the in situ analysis of various engineering processes. A brief review of spectroscopic imaging principles and existing applications is provided as background before three novel applications are set forth. First, the effectiveness of FTIR imaging for modeling polymer dissolution behavior was examined in a series of binary poly (methyl methacrylate) (PMMA) systems. The dissolution behavior was influenced by polymer conformation as well as the solvent characteristics. The results indicate that chemistry alone is a poor predictor of dissolution rate. Rather, the diffusion coefficients of both the polymer and solvent have a foremost impact on the dissolution process. One major complication in modeling diffusion-related process by FTIR imaging is the precise determination of component locations in a series of images. This issue is addressed through the introduction of a new position-reporting technique based on hypothesis testing. A rudimentary drug release system, consisting of a poly (ethylene-co-vinyl acetate) film and a nicotine solution, was used to illustrate the importance of precisely reporting the nicotine diffusion front position. The new reporting method provided an inherent level of certainty to the position report. This method was applied to qualitatively assess the uptake of nicotine from solutions containing different solubilizing agents, which were capable of either promoting or inhibiting nicotine uptake. Finally, Raman mapping and Raman line imaging were used to classify individual carbon nanotubes that were dispersed on a substrate. Individual nanotubes displayed a range of spectral characteristics, indicating that the bulk sample was a mixture of materials with different graphitic domain sizes. The results from images acquired

  13. In vivo and in situ monitoring of the nitric oxide stimulus response of single cancer cells by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Su, L.; Chen, Y.; Zhang, G. N.; Wang, L. H.; Shen, A. G.; Zhou, X. D.; Wang, X. H.; Hu, J. M.

    2013-04-01

    Raman spectroscopy is capable of studying time-resolved information of selected biomolecular distributions inside individual cells without labeling. In this study, Raman spectroscopy was for the first time utilized to in vivo and in situ monitor the cellular response to nitric oxide (NO) in single oral squamous cell carcinoma (OSCC) cells over a period of 24 h. Sodium nitroprusside (SNP) was chosen as a NO donor to be incubated with the OSCC cell line (TCA8113) for certain time intervals. In vivo and in situ Raman analysis revealed that the degradation and conformational changes of nucleic acids, lipids and proteins could be directly observed by changes in the characteristic Raman bands. In comparison with conventional flow cytometric analysis, Raman spectroscopy not only detected more subtle NO-induced chemical changes of cells, where the SNP concentration could be even less than 1 mM, but also provided a full view of the whole chemical components of single cells. Raman spectroscopy therefore is an important candidate for label-free, nondestructive and in situ monitoring of cellular changes in response to chemotherapeutic agents, which could potentially be used in rapid screening of novel drugs.

  14. In Situ and In Vivo Molecular Analysis by Coherent Raman Scattering Microscopy.

    PubMed

    Liao, Chien-Sheng; Cheng, Ji-Xin

    2016-06-12

    Coherent Raman scattering (CRS) microscopy is a high-speed vibrational imaging platform with the ability to visualize the chemical content of a living specimen by using molecular vibrational fingerprints. We review technical advances and biological applications of CRS microscopy. The basic theory of CRS and the state-of-the-art instrumentation of a CRS microscope are presented. We further summarize and compare the algorithms that are used to separate the Raman signal from the nonresonant background, to denoise a CRS image, and to decompose a hyperspectral CRS image into concentration maps of principal components. Important applications of single-frequency and hyperspectral CRS microscopy are highlighted. Potential directions of CRS microscopy are discussed. PMID:27306307

  15. In Situ and In Vivo Molecular Analysis by Coherent Raman Scattering Microscopy

    NASA Astrophysics Data System (ADS)

    Liao, Chien-Sheng; Cheng, Ji-Xin

    2016-06-01

    Coherent Raman scattering (CRS) microscopy is a high-speed vibrational imaging platform with the ability to visualize the chemical content of a living specimen by using molecular vibrational fingerprints. We review technical advances and biological applications of CRS microscopy. The basic theory of CRS and the state-of-the-art instrumentation of a CRS microscope are presented. We further summarize and compare the algorithms that are used to separate the Raman signal from the nonresonant background, to denoise a CRS image, and to decompose a hyperspectral CRS image into concentration maps of principal components. Important applications of single-frequency and hyperspectral CRS microscopy are highlighted. Potential directions of CRS microscopy are discussed.

  16. In situ Raman spectroscopy study of metal-enhanced hydrogenation and dehydrogenation of VO2.

    PubMed

    Wu, Hao; Fu, Qiang; Bao, Xinhe

    2016-11-01

    Vanadium dioxide (VO2) has a phase transition from insulator to metal at 340 K, and this transition can be strongly modified by hydrogenation. In this work, two dimensional (2D) VO2 sheets have been grown on Si(1 1 1) surfaces through chemical vapor deposition, and metal (Au, Pt) thin films were deposited on VO2 surfaces by sputtering. The hydrogenation and dehydrogenation of VO2 and metal-decorated VO2 structures in H2 and in air were in situ studied by Raman. We found that hydrogenation and dehydrogenation temperatures have been significantly decreased with the VO2 surface decorated by Au and Pt. The enhanced hydrogenation and dehydrogenation reactions can be attributed to catalytic dissociation of H2 and O2 molecules on metal surfaces and subsequent spillover of dissociated H and O atoms to the oxide surfaces. PMID:27603090

  17. In situ Raman spectroscopic investigation of the structure of subduction-zone fluids

    USGS Publications Warehouse

    Mibe, Kenji; Chou, I.-Ming; Bassett, William A.

    2008-01-01

    In situ Raman spectra of synthetic subduction-zone fluids (KAlSi3O8-H2O system) were measured to 900?? and 2.3 GPa using a hydrothermal diamond-anvil cell. The structures of aqueous fluid and hydrous melt become closer when conditions approach the second critical endpoint. Almost no three-dimensional network was observed in the supercritical fluid above 2 GPa although a large amount of silicate component is dissolved, suggesting that the physical and chemical properties of these phases change drastically at around the second critical endpoint. Our experimental results indicate that the fluids released from a subducting slab change from aqueous fluid to supercritical fluid with increasing depth under the volcanic arcs. Copyright 2008 by the American Geophysical Union.

  18. In situ Raman study of dissolved CaCO3 minerals under subduction zone conditions

    NASA Astrophysics Data System (ADS)

    Facq, S.; Daniel, I.; Sverjensky, D. A.

    2012-12-01

    The fate and the characteristics of the Earth's deep carbon reservoirs are still not well understood [1]. The connection between the surficial and the deep-Earth carbon cycles occurs at subduction zones where carbon is transported into the mantle and where hydrous silicates and carbonate minerals break down releasing H2O and C-species in fluids associated with mantle metasomatism and the generation of arc volcanism [2]. In order to obtain mass balance between recycling and burial in the deep mantle, the study of the dissolution of CaCO3 minerals in equilibrium with aqueous fluids under mantle conditions is crucial. We report a novel integrated experimental and theoretical study of the equilibration of CaCO3 minerals with aqueous solutions (pure water or NaCl solutions) at high pressures and temperatures (0.5 to 8 GPa and 250 to 500 °C). The fluid speciation was studied using in situ Raman spectroscopy coupled to an externally heated membrane type DAC equipped with 500 μm pure synthetic diamond anvils. In a typical experiment, the aqueous fluid and a calcite crystal [3] were loaded in a rhenium gasket. The pressure was determined from the calibrated shift of the carbonate υ1 symmetric stretching mode of aragonite and the temperature measured with a K-type thermocouple. Raman spectra were recorded using a Labram HR800 Raman spectrometer (Horiba Jobin-Yvon) coupled to a Spectra Physics Ar+ laser. At equilibrium with an aragonite crystal, the Raman data show that bicarbonate is the most abundant species in low-pressure fluids (below 4 GPa) whereas carbonate becomes progressively dominant at higher pressure. After correction from their Raman cross-sections [4], the relative amounts of dissolved carbonate and bicarbonate were estimated from the areas of the Raman bands of the carbonate and bicarbonate ions (υ1 and υ5 symmetric stretching modes, respectively). The presence of sodium chloride influences the speciation by extending the pressure field where the

  19. Boron phosphide under pressure: In situ study by Raman scattering and X-ray diffraction

    SciTech Connect

    Solozhenko, Vladimir L.; Kurakevych, Oleksandr O.; Le Godec, Yann; Kurnosov, Aleksandr V.; Oganov, Artem R.

    2014-07-21

    Cubic boron phosphide, BP, has been studied in situ by X-ray diffraction and Raman scattering up to 55 GPa at 300 K in a diamond anvil cell. The bulk modulus of B{sub 0} = 174(2) GPa has been established, which is in excellent agreement with our ab initio calculations. The data on Raman shift as a function of pressure, combined with equation-of-state (EOS) data, allowed us to estimate the Grüneisen parameters of the TO and LO modes of zinc-blende structure, γ{sub G}{sup TO }= 1.26 and γ{sub G}{sup LO }= 1.13, just like in the case of other A{sup III}B{sup V} diamond-like phases, for which γ{sub G}{sup TO }> γ{sub G}{sup LO }≅ 1. We also established that the pressure dependence of the effective electro-optical constant α is responsible for a strong change in relative intensities of the TO and LO modes from I{sub TO}/I{sub LO} ∼ 0.25 at 0.1 MPa to I{sub TO}/I{sub LO} ∼ 2.5 at 45 GPa, for which we also find excellent agreement between experiment and theory.

  20. Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy.

    PubMed

    Huang, Yi-Fan; Kooyman, Patricia J; Koper, Marc T M

    2016-01-01

    Understanding the atomistic details of how platinum surfaces are oxidized under electrochemical conditions is of importance for many electrochemical devices such as fuel cells and electrolysers. Here we use in situ shell-isolated nanoparticle-enhanced Raman spectroscopy to identify the intermediate stages of the electrochemical oxidation of Pt(111) and Pt(100) single crystals in perchloric acid. Density functional theory calculations were carried out to assist in assigning the experimental Raman bands by simulating the vibrational frequencies of possible intermediates and products. The perchlorate anion is suggested to interact with hydroxyl phase formed on the surface. Peroxo-like and superoxo-like two-dimensional (2D) surface oxides and amorphous 3D α-PtO2 are sequentially formed during the anodic polarization. Our measurements elucidate the process of the electrochemical oxidation of platinum single crystals by providing evidence for the structure-sensitive formation of a 2D platinum-(su)peroxide phase. These results may contribute towards a fundamental understanding of the mechanism of degradation of platinum electrocatalysts. PMID:27514695

  1. Intermediate stages of electrochemical oxidation of single-crystalline platinum revealed by in situ Raman spectroscopy

    PubMed Central

    Huang, Yi-Fan; Kooyman, Patricia J.; Koper, Marc T. M.

    2016-01-01

    Understanding the atomistic details of how platinum surfaces are oxidized under electrochemical conditions is of importance for many electrochemical devices such as fuel cells and electrolysers. Here we use in situ shell-isolated nanoparticle-enhanced Raman spectroscopy to identify the intermediate stages of the electrochemical oxidation of Pt(111) and Pt(100) single crystals in perchloric acid. Density functional theory calculations were carried out to assist in assigning the experimental Raman bands by simulating the vibrational frequencies of possible intermediates and products. The perchlorate anion is suggested to interact with hydroxyl phase formed on the surface. Peroxo-like and superoxo-like two-dimensional (2D) surface oxides and amorphous 3D α-PtO2 are sequentially formed during the anodic polarization. Our measurements elucidate the process of the electrochemical oxidation of platinum single crystals by providing evidence for the structure-sensitive formation of a 2D platinum-(su)peroxide phase. These results may contribute towards a fundamental understanding of the mechanism of degradation of platinum electrocatalysts. PMID:27514695

  2. Hydrolysis of polycarbonate in sub-critical water in fused silica capillary reactor with in situ Raman spectroscopy

    USGS Publications Warehouse

    Pan, Z.; Chou, I.-Ming; Burruss, R.C.

    2009-01-01

    The advantages of using fused silica capillary reactor (FSCR) instead of conventional autoclave for studying chemical reactions at elevated pressure and temperature conditions were demonstrated in this study, including the allowance for visual observation under a microscope and in situ Raman spectroscopic characterization of polycarbonate and coexisting phases during hydrolysis in subcritical water. ?? 2009 The Royal Society of Chemistry.

  3. Charge transfer in carbon nanotube actuators investigated using in situ Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Hughes, M.; Windle, A. H.; Robertson, J.

    2004-02-01

    Charge transfer dynamics on the surface of single-wall carbon nanotube sheets is investigated using in situ Raman spectroscopy in order to understand the actuation mechanism of an electrochemical actuator and to determine associated parameters. We built an actuator from single-wall carbon nanotube mat and studied its actuation in several alkali metal (Li, Na, and K) and alkaline earth (Ca) halide and sulfate solutions in order to clarify the role of counterion as mobile ions in the film. The variation of bonding with applied potential was monitored using in situ Raman spectroscopy. This is because Raman can detect changes in C-C bond length: the radial breathing mode at ˜190 cm-1 varies inversely with the nanotube diameter, and the G band at ˜1590 cm-1 varies with the axial bond length. In addition, the intensities of both the modes vary with the emptying/depleting or filling of the bonding and antibonding states due to electrochemical charge injection. We discussed the variation of peak height and wave numbers of these modes providing valuable information concerning electrochemical charge injection on the carbon nanotube mat surface. We found in-plane microscopic compressive strain (˜-0.25%) and the equivalent charge transfer per carbon atom (fc˜-0.005) as an upper bound for the actuators studied hereby. It is demonstrated that though the present analysis does comply with the proposition for the actuation principle made earlier, the quantitative estimates are significantly lower if compared with those of reported values. Furthermore, the extent of variation, i.e., coupled electro-chemo-mechanical response of single-wall carbon nanotubes (SWNT) mat depended upon the type of counterion used (Group I versus Group II). The cyclic voltammetry and ac electrochemical impedance spectroscopy results were described briefly, which help to demonstrate well-developed capacitive behavior of SWNT mat and to estimate the specific capacitances as well. Summarizing, the impact

  4. Interfacial processes studied by coupling electrochemistry at the polarised liquid-liquid interface with in situ confocal Raman spectroscopy.

    PubMed

    Poltorak, Lukasz; Dossot, Manuel; Herzog, Grégoire; Walcarius, Alain

    2014-12-28

    Interfacial processes controlled by ion transfer voltammetry at the interface between two immiscible electrolyte solutions were studied by in situ Raman spectroscopy. Raman spectra of the interface between a 5 mM NaCl aqueous solution and 10 mM bis(triphenyl-phosphoranydieneammonium) tetrakis(4-chlorophenyl)borate in 1,2-dichloroethane were recorded at open circuit potential and at various interfacial potential differences. At open-circuit potential, Raman peaks assigned to vibrational modes of 1,2-dichloroethane are clearly visible and peaks of weak intensity are measured for the organic electrolyte ions. When a negative interfacial potential difference is applied, the intensity of the peaks of the cation of the organic electrolyte increases, confirming its transfer induced by the interfacial potential difference applied. The electrochemically assisted generation of mesoporous silica deposits was then followed by in situ confocal Raman spectroscopy. The condensation of mesoporous silica was controlled by the transfer of cetyltrimethylammonium (CTA(+)) ions to an aqueous phase containing hydrolysed silanes. The transfer of CTA(+) at the interface was monitored in situ by confocal Raman spectroscopy, and formation of silica was observed. PMID:25377062

  5. Quantitative Raman Spectroscopy to monitor microbial metabolism in situ under pressure

    NASA Astrophysics Data System (ADS)

    Picard, A.; Daniel, I.; Oger, P.

    2006-12-01

    Although high hydrostatic pressure (HHP) biotopes are ubiquitous on Earth, little is known about the metabolism of piezophile organisms. Cell culture under HHP can be technically challenging, and equipment- dependent. In addition, the depressurization step required for analysis can lead to erroneous data. Therefore, to understand how piezophile organisms react to pressure, it is crucial to be able to monitor their activity in situ under HHP. We developed the use of Quantitative Raman Spectroscopy (QRS, 1) to monitor in situ the metabolism of organic molecules. This technique is based on the specific spectral signature of an analyte from which its concentration can be deduced. An application of this technique to the monitoring of alcoholic fermentation by the piezotolerant micro-eucaryote Saccharomyces cerevisiae is presented. Ethanol fermentation from glucose was monitored during 24h from ambient P up to 100 MPa in the low- pressure Diamond Anvil Cell (lpDAC, 2). The experimental compression chamber consisted in a 300 μm-thick Ni gasket in which a 500 μm-diameter hole was drilled. Early-stationnary yeast cells were inoculated into fresh low-fluorescence medium containing 0.15 M of glucose. Ethanol concentration was determined in situ by QRS using the symmetric C-C stretching mode of ethanol at 878 cm-1 normalizing the data to the intensity of the sulfate S-O stretching mode at 980 cm-1. In our setup, the detection limit of ethanol is lower than 0.05 mM with a precision below 1%. At ambient P, ethanol production in the lpDAC and in control experiments proceeds with the same kinetics. Thus, yeast is not affected by its confinement. This is further confirmed by its ability to bud with a generation time similar to control experiments performed in glass tubes at ambient pressure inside the lpDAC. Ethanol production by yeast occurs to at least 65 MPa (3). At 10 MPa, fermentation proceeds 3 times faster than at ambient P. Fermentation rates decrease linearly from 20 to

  6. Simulating Realistic Imaging Conditions For In-Situ Liquid Microscopy

    PubMed Central

    Welch, David A.; Faller, Roland; Evans, James E.; Browning, Nigel D.

    2013-01-01

    In situ transmission electron microscopy enables the imaging of biological cells, macromolecular protein complexes, nanoparticles, and other systems in a near-native environment. In order to improve interpretation of image contrast features and also predict ideal imaging conditions ahead of time, new virtual electron microscopic techniques are needed. A technique for virtual fluid-stage high-angle annular dark-field scanning transmission electron microscopy with the multislice method is presented that enables the virtual imaging of model fluid-stage systems composed of millions of atoms. The virtual technique is exemplified by simulating images of PbS nanoparticles under different imaging conditions and the results agree with previous experimental findings. General insight is obtained on the influence of the effects of fluid path length, membrane thickness, nanoparticle position, defocus and other microscope parameters on attainable image quality. PMID:23872040

  7. Simulating realistic imaging conditions for in situ liquid microscopy

    SciTech Connect

    Welch, David A.; Faller, Roland; Evans, James E.; Browning, Nigel D.

    2013-12-01

    In situ transmission electron microscopy enables the imaging of biological cells, macromolecular protein complexes, nanoparticles, and other systems in a near-native environment. In order to improve interpretation of image contrast features and also predict ideal imaging conditions ahead of time, new virtual electron microscopic techniques are needed. A technique for virtual fluid-stage high-angle annular dark-field scanning transmission electron microscopy with the multislice method is presented that enables the virtual imaging of model fluid-stage systems composed of millions of atoms. The virtual technique is exemplified by simulating images of PbS nanoparticles under different imaging conditions and the results agree with previous experimental findings. General insight is obtained on the influence of the effects of fluid path length, membrane thickness, nanoparticle position, defocus and other microscope parameters on attainable image quality.

  8. In situ Raman-based detections of the hydrothermal vent and cold seep fluids

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Du, Zengfeng; Zheng, Ronger; Luan, Zhendong; Qi, Fujun; Cheng, Kai; Wang, Bing; Ye, Wangquan; Liu, Xiaorui; Chen, Changan; Guo, Jinjia; Li, Ying; Yan, Jun

    2016-04-01

    Hydrothermal vents and cold seeps, and their associated biological communities play an important role in global carbon and sulphur biogeochemical cycles. Most of the studies of fluid composition geochemistry are based on recovered samples, both with gas-tight samplers and as open specimens, but the in situ conditions are difficult to maintain in recovered samples. Determination in situ of the chemical signals of the emerging fluids are challenging due to the high pressure, often strongly acidic and temperature in which few sensors can survive. Most of those sensors used so far are based on electrochemistry, and can typically detect only a few chemical species. Here we show that direct measurement of critical chemical species of hydrothermal vents and cold seeps can be made rapidly and in situ by means of a new hybrid version of earlier deep-sea pore water Raman probe carried on the ROV (Remote Operated Vehicle) Faxian. The fluid was drawn through the probe by actuating a hydraulic pump on the ROV, and measured at the probe optical cell through a sapphire window. We have observed the concentrations of H2S, HS‑, SO42‑, HSO4‑, CO2, and H2 in hydrothermal vent fluids from the Pacmanus and Desmos vent systems in the Manus back-arc basin, Papua New Guinea. Two black smokers (279° C and 186° C) at the Pacmanus site showed the characteristic loss of SO42‑, and the increase of CO2 and well resolved H2S and HS‑ peaks. At the white smoker of Onsen site the strong HSO4‑peak observed at high temperature quickly dropped with strong accompanying increase of SO42‑and H2 peaks when the sample contained in the Raman sensing cell was removed from the hot fluid due to rapid thermal deprotonation. We report here also the finding of a new lower temperature (88° C) white smoker "Kexue" field at the Desmos site with strong H2S, HS‑ and CO2 signals. We also have detected the concentrations of CH4,H2S, HS‑, SO42‑, and S8 in cold seep fluids and the surrounding

  9. In Situ Raman Spectroscopic Study of Barite as a Pressure Gauge Using a Hydrothermal Diamond Anvil Cell.

    PubMed

    Liu, Chuanjiang; Wang, Duojun; Zheng, Haifei

    2016-02-01

    In situ Raman measurements of barite were performed at temperatures in the range of 298-673 K and pressures in the range of 105-1217 MPa using a hydrothermal diamond anvil cell combined with laser Raman spectroscopy. The Raman frequency and the full width at half maximum (FWHM) of the most intense ν1 Raman peak for barite as a function of pressure and temperature were obtained. In the experimental P-T ranges, the ν1Raman band systematically shifted toward low wavenumbers with increasing pressure and temperature. The positive pressure dependence of ν1Raman frequency indicates stress-induced shortening of the S-O bond, whereas the negative temperature dependence shows temperature-induced expansion of the S-O bond. In contrast, the observed ν1Raman band became broadened, which should be attributed to the reduced ordering of molecular structure. Based on the obtained data, the established relationships among the Raman shift or the FWHM, pressure and temperature can be used to obtain good estimates of the internal pressure in natural barite-bearing fluid inclusions or hydrothermal diamond anvil cell. This is a sensitive and reliable approach to the accurate determination of geological pressure. PMID:26903568

  10. Raman Hyperspectral Imaging of Microfossils: Potential Pitfalls

    PubMed Central

    Olcott Marshall, Alison

    2013-01-01

    Abstract Initially, Raman spectroscopy was a specialized technique used by vibrational spectroscopists; however, due to rapid advancements in instrumentation and imaging techniques over the last few decades, Raman spectrometers are widely available at many institutions, allowing Raman spectroscopy to become a widespread analytical tool in mineralogy and other geological sciences. Hyperspectral imaging, in particular, has become popular due to the fact that Raman spectroscopy can quickly delineate crystallographic and compositional differences in 2-D and 3-D at the micron scale. Although this rapid growth of applications to the Earth sciences has provided great insight across the geological sciences, the ease of application as the instruments become increasingly automated combined with nonspecialists using this techique has resulted in the propagation of errors and misunderstandings throughout the field. For example, the literature now includes misassigned vibration modes, inappropriate spectral processing techniques, confocal depth of laser penetration incorrectly estimated into opaque crystalline solids, and a misconstrued understanding of the anisotropic nature of sp2 carbons. Key Words: Raman spectroscopy—Raman imaging—Confocal Raman spectroscopy—Disordered sp2 carbons—Hematite—Microfossils. Astrobiology 13, 920–931. PMID:24088070

  11. Investigation of the thermal stability of phosphotungstic Wells-Dawson heteropoly-acid through in situ Raman spectroscopy

    SciTech Connect

    Matkovic, Silvana Raquel; Briand, Laura Estefania; Banares, Miguel Angel

    2011-11-15

    Highlights: {yields} Insitu Raman is used to monitor the thermal stability of Wells Dawson heteropolyacid. {yields} TP-Raman follows the gradual dehydration and the effect on the secondary structure. {yields} Wells-Dawson heteropolyacid does not decompose into Keggin and WO{sub 3} units below 600{sup o}C -- Abstract: The present investigation applies laser Raman spectroscopy under in situ conditions to obtain insights on the effect of the temperature on the molecular structure of the bulk phosphotungstic Wells-Dawson heteropoly-acid H{sub 6}P{sub 2}W{sub 18}O{sub 62}.xH{sub 2}O (HPA). The in situ temperature-programmed studies followed the evolution of phosphotungstic Wells-Dawson and Keggin heteropoly-acids along with tungsten trioxide under controlled atmosphere and temperature. The spectroscopic investigation of the Wells-Dawson HPA demonstrated that in situ Raman spectroscopy is a suitable technique to follow the effect of a gradual dehydration on the secondary structure of such a complex structure. Moreover, the absence of the signals belonging either to the Keggin or WO{sub 3} phases provides further evidence that the phosphotungstic heteropolyanion does not decomposes towards those materials at temperatures below 600 {sup o}C.

  12. Mobile system for in-situ imaging of cultural objects

    NASA Astrophysics Data System (ADS)

    Zemlicka, J.; Jakubek, J.; Krejci, F.; Hradil, D.; Hradilova, J.; Mislerova, H.

    2012-01-01

    Non-invasive analytical techniques recently developed with the Timepix pixel detector have shown great potential for the inspection of objects of cultural heritage. We have developed new instrumentation and methodology for in-situ X-ray transmission radiography and X-ray fluorescence imaging and successfully tested and evaluated a mobile system for remote terrain tasks. The prototype portable imaging device comprises the radiation source tube and the spectral sensitive X-ray camera. Both components can be moreover mounted on independent motorized positioning systems allowing adaptation of irradiation geometry to the object shape. Both parts are placed onto a pair of universal portable holders (tripods). The detector is placed in a shielded box with exchangeable entrance window (beam filters and pinhole collimator). This adjustable setup allows performing in-situ measurements for both transmission and emission (XRF) radiography. The assembled system has been successfully tested in our laboratory with phantoms and real samples. The obtained and evaluated results are presented in this paper. Future work will include successive adaptation of the current system for real in-situ utilization and preparation of software allowing semi-automatic remote control of measurements.

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

    PubMed

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

    2012-06-15

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

  14. In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

    SciTech Connect

    Saint-Amans, C.; Hébert, P. Doucet, M.; Resseguier, T. de

    2015-01-14

    We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

  15. In-situ Raman spectroscopy and high-speed photography of a shocked triaminotrinitrobenzene based explosive

    NASA Astrophysics Data System (ADS)

    Saint-Amans, C.; Hébert, P.; Doucet, M.; de Resseguier, T.

    2015-01-01

    We have developed a single-shot Raman spectroscopy experiment to study at the molecular level the initiation mechanisms that can lead to sustained detonation of a triaminotrinitrobenzene-based explosive. Shocks up to 30 GPa were generated using a two-stage laser-driven flyer plate generator. The samples were confined by an optical window and shock pressure was maintained for at least 30 ns. Photon Doppler Velocimetry measurements were performed at the explosive/window interface to determine the shock pressure profile. Raman spectra were recorded as a function of shock pressure and the shifts of the principal modes were compared to static high-pressure measurements performed in a diamond anvil cell. Our shock data indicate the role of temperature effects. Our Raman spectra also show a progressive extinction of the signal which disappears around 9 GPa. High-speed photography images reveal a simultaneous progressive darkening of the sample surface up to total opacity at 9 GPa. Reflectivity measurements under shock compression show that this opacity is due to a broadening of the absorption spectrum over the entire visible region.

  16. Electrolytic synthesis of aqueous aluminum nanoclusters and in situ characterization by femtosecond Raman spectroscopy and computations

    PubMed Central

    Wang, Wei; Liu, Weimin; Chang, I-Ya; Wills, Lindsay A.; Zakharov, Lev N.; Boettcher, Shannon W.; Cheong, Paul Ha-Yeon; Fang, Chong; Keszler, Douglas A.

    2013-01-01

    The selective synthesis and in situ characterization of aqueous Al-containing clusters is a long-standing challenge. We report a newly developed integrated platform that combines (i) a selective, atom-economical, step-economical, scalable synthesis of Al-containing nanoclusters in water via precision electrolysis with strict pH control and (ii) an improved femtosecond stimulated Raman spectroscopic method covering a broad spectral range of ca. 350–1,400 cm−1 with high sensitivity, aided by ab initio computations, to elucidate Al aqueous cluster structures and formation mechanisms in real time. Using this platform, a unique view of flat [Al13(μ3-OH)6(μ2-OH)18(H2O)24](NO3)15 nanocluster formation is observed in water, in which three distinct reaction stages are identified. The initial stage involves the formation of an [Al7(μ3-OH)6(μ2-OH)6(H2O)12]9+ cluster core as an important intermediate toward the flat Al13 aqueous cluster. PMID:24167254

  17. In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy

    PubMed Central

    Wang, Fei; Wang, Hua-Lin; Qiu, Yang; Chang, Yu-Long; Long, Yi-Tao

    2015-01-01

    In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation. PMID:26687436

  18. Reduction Dynamics of Doped Ceria, Nickel Oxide, and Cermet Composites Probed Using In Situ Raman Spectroscopy

    PubMed Central

    Shearing, Paul R.; Brightman, Edward; Brett, Dan J. L.; Brandon, Nigel P.; Cohen, Lesley F.

    2016-01-01

    The redox properties of gadolinium doped ceria (CGO) and nickel oxide (NiO) composite cermets underpin the operation of solid oxide electrochemical cells. Although these systems have been widely studied, a full comprehension of the reaction dynamics at the interface of these materials is lacking. Here, in situ Raman spectroscopic monitoring of the redox cycle is used to investigate the interplay between the dynamic and competing processes of hydrogen spillover and water dissociation on the doped ceria surface. In order to elucidate these mechanisms, the redox process in pure CGO and NiO is studied when exposed to wet and dry hydrogen and is compared to the cermet behavior. In dry hydrogen, CGO reduces relatively rapidly via a series of intermediate phases, while NiO reduces via a single‐step process. In wet reducing atmospheres, however, the oxidation state of pure CGO is initially stabilized due to the dissociation of water by reduced Ce(III) and subsequent incorporation of oxygen into the structure. In the reduction process involving the composite cermet, the close proximity of the NiO improves the efficiency and speed of the composite reduction process. Although NiO is already incorporated into working cells, these observations suggest direct routes to further improve cell performance. PMID:27595058

  19. In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy.

    PubMed

    Wang, Fei; Wang, Hua-Lin; Qiu, Yang; Chang, Yu-Long; Long, Yi-Tao

    2015-01-01

    In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation. PMID:26687436

  20. In situ noninvasive Raman microspectroscopic investigation of polychrome plasterworks in the Alhambra.

    PubMed

    Dominguez-Vidal, Ana; de la Torre-Lopez, Maria Jose; Rubio-Domene, Ramon; Ayora-Cañada, Maria Jose

    2012-12-21

    A totally non-invasive in situ investigation in one of the main halls of the Palace of the Lions in the Alhambra (Granada, Spain) has been carried out. Analyses were made with a fiber-optic portable Raman microspectrometer placed on scaffolding platforms at a height of ca. 12 m above the ground level during the period of conservation works. The objects of this study are the decorated plasterworks in the seven vaults of the Hall of the Kings. Together with the results, the different practical problems related to the positioning of the instrumental setup and the influence of the local environment during the analysis are discussed. In general, high quality spectra were obtained despite difficulties for micro-probe head positioning and sometimes the vibrations of the corresponding scaffold. Different typical antiquity pigments have been identified: cinnabar, minium, carbon black and lapis lazuli. Furthermore, the luminescence pattern from lapis lazuli found in most blue decorations has allowed the establishment of the natural origin and provenance of the pigment. Apart from this natural lapis lazuli, synthetic ultramarine blue was also found in one of the vaults showing up a recent restoration. In addition, some degradation products of cinnabar and minium were identified, with the major advantage of providing real-time information to the conservators during their work. PMID:23085888

  1. Nanoscale Silicon as a Catalyst for Graphene Growth: Mechanistic Insight from in Situ Raman Spectroscopy

    SciTech Connect

    Share, Keith; Carter, Rachel; Nikolaev, Pavel; Hooper, Daylong; Oakes, Landon; Cohn, Adam; Rao, Rahul; Puretzky, Alexander A; Geohegan, David; Maruyama,; Pint, Cary

    2016-01-01

    Nanoscale carbons are typically synthesized by thermal decomposition of a hydrocarbon at the surface of a metal catalyst.1,2 Whereas the use of silicon as an alternative to metal catalyst could unlock new techniques to seamlessly couple carbon nanostructures and semiconductor materials, stable carbide formation in bulk silicon prevents the precipitation and growth of graphitic structures.3,4 Here, we provide evidence supported by comprehensive in-situ Raman experiments that indicates nanoscale grains of silicon in porous silicon scaffolds act as catalysts for hydrocarbon decomposition and growth of few-layered graphene materials at temperatures as low as 700 K. Self-limiting growth kinetics of carbon with activation energies measured between 0.32 0.37 eV elucidates the formation of highly reactive surface-bound Si radicals that aid in the decomposition of hydrocarbons. Nucleation and growth of graphitic carbon layers on porous silicon exhibits striking similarity to catalytic growth on nickel surfaces, involving temperature dependent surface and subsurface diffusion of carbon. This work elucidates how the nanoscale properties of silicon can be exploited to yield catalytic properties distinguished from bulk materials, opening an important avenue to engineer catalytic interfaces combining the two most technologically-important materials for modern applications silicon and nanoscale carbons.

  2. In situ analysis of dynamic laminar flow extraction using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Fei; Wang, Hua-Lin; Qiu, Yang; Chang, Yu-Long; Long, Yi-Tao

    2015-12-01

    In this study, we performed micro-scale dynamic laminar flow extraction and site-specific in situ chloride concentration measurements. Surface-enhanced Raman spectroscopy was utilized to investigate the diffusion process of chloride ions from an oil phase to a water phase under laminar flow. In contrast to common logic, we used SERS intensity gradients of Rhodamine 6G to quantitatively calculate the concentration of chloride ions at specific positions on a microfluidic chip. By varying the fluid flow rates, we achieved different extraction times and therefore different chloride concentrations at specific positions along the microchannel. SERS spectra from the water phase were recorded at these different positions, and the spatial distribution of the SERS signals was used to map the degree of nanoparticle aggregation. The concentration of chloride ions in the channel could therefore be obtained. We conclude that this method can be used to explore the extraction behaviour and efficiency of some ions or molecules that enhance the SERS intensity in water or oil by inducing nanoparticle aggregation.

  3. Nanoscale Silicon as a Catalyst for Graphene Growth: Mechanistic Insight from in Situ Raman Spectroscopy

    DOE PAGESBeta

    Share, Keith; Carter, Rachel E.; Nikolaev, Pavel; Hooper, Daylong; Oakes, Landon; Cohn, Adam P.; Rao, Rahul; Puretzky, Alexander A.; Geohegan, David B.; Maruyama, Benji; et al

    2016-06-08

    Nanoscale carbons are typically synthesized by thermal decomposition of a hydrocarbon at the surface of a metal catalyst. Whereas the use of silicon as an alternative to metal catalysts could unlock new techniques to seamlessly couple carbon nanostructures and semiconductor materials, stable carbide formation renders bulk silicon incapable of the precipitation and growth of graphitic structures. In this article, we provide evidence supported by comprehensive in situ Raman experiments that indicates nanoscale grains of silicon in porous silicon (PSi) scaffolds act as catalysts for hydrocarbon decomposition and growth of few-layered graphene at temperatures as low as 700 K. Self-limiting growthmore » kinetics of graphene with activation energies measured between 0.32–0.37 eV elucidates the formation of highly reactive surface-bound Si radicals that aid in the decomposition of hydrocarbons. Nucleation and growth of graphitic layers on PSi exhibits striking similarity to catalytic growth on nickel surfaces, involving temperature dependent surface and subsurface diffusion of carbon. Lastly, this work elucidates how the nanoscale properties of silicon can be exploited to yield catalytic properties distinguished from bulk silicon, opening an important avenue to engineer catalytic interfaces combining the two most technologically important materials for modern applications—silicon and nanoscale carbons.« less

  4. Resonance Raman Spectroscopy for In-Situ Monitoring of Radiation Damage

    SciTech Connect

    Meents, A.; Owen, R. L.; Schneider, R.; Pradervand, C.; Schulze-Briese, C.; Murgida, D.; Hildebrandt, P.; Bohler, P

    2007-01-19

    Radiation induced damage of metal centres in proteins is a severe problem in X-ray structure determination. Photoreduction can lead to erroneous structural implications, and in the worst cases cause structure solution to fail. Resonance Raman (RR) spectroscopy is well suited in-situ monitoring of X-ray induced photoreduction. However the laser excitation needed for RR can itself cause photoreduction of the metal centres. In the present study myoglobin and rubredoxin crystals were used as model systems to assess the feasibility of using RR for this application. It is shown that at least 10-15 RR spectra per crystal can be recorded at low laser power before severe photoreduction occurs. Furthermore it is possible to collect good quality RR spectra from cryocooled protein crystals with exposure times of only a few seconds. Following extended laser illumination photoreduction is observed through the formation and decay of spectral bands as a function of dose. The experimental setup planned for integration into the SLS protein crystallography beamlines is also described. This setup should also prove to be very useful for other experimental techniques at synchrotrons where X-ray photoreduction is a problem e.g. X-ray absorption spectroscopy.

  5. In situ assessment of tumor vascularity using fluorine NMR imaging.

    PubMed

    Ceckler, T L; Gibson, S L; Hilf, R; Bryant, R G

    1990-03-01

    In situ fluorine NMR imaging has been used to measure vascularity in subcutaneously implanted mammary tumors. Oxyferol, a perfluorinated blood substitute comprised of an emulsion of 25% w/v perfluorotributylamine, was used as a tracer. Following iv administration, this perfluorocarbon emulsion remains primarily in the vasculature during the image acquisition period. The distribution of the PFTA in the 19F NMR image gives a map of tissue regions with intact vascularity. This technique has been used to demonstrate decreased blood flow in necrotic regions of R3230AC mammary tumors in which vasculature had been damaged either as a result of spontaneous necrosis or by photodynamic therapy (PDT). Damage to tumor vascularity following PDT was observed prior to the development of necrosis. PMID:2325542

  6. Raman spectroscopic identification of arsenate minerals in situ at outcrops with handheld (532 nm, 785 nm) instruments.

    PubMed

    Culka, Adam; Kindlová, Helena; Drahota, Petr; Jehlička, Jan

    2016-02-01

    Minerals are traditionally identified under field conditions by experienced mineralogists observing the basic physical properties of the samples. Under laboratory conditions, a plethora of techniques are commonly used for identification of the geological phases based on their structural and spectroscopic parameters. In this area, Raman spectrometry has become a useful tool to complement the more widely applied XRD. Today, however, there is an acute need for a technique for unambiguous in situ identification of minerals, within the geological as well as planetary/exobiology realms. With the potential for miniaturization, Raman spectroscopy can be viewed as a practical technique to achieve these goals. Here, for the first time, the successful application of handheld Raman spectrometers is demonstrated to detect and discriminate arsenic phases in the form of earthy aggregates. The Raman spectroscopic analyses of arsenate minerals were performed in situ using two handheld instruments, using 532 and 785 nm excitation. Bukovskýite, kaňkite, parascorodite, and scorodite were identified from Kaňk near Kutná Hora, CZE; kaňkite, scorodite, and zýkaite were identified at the Lehnschafter gallery in an old silver mine at Mikulov near Teplice, Bohemian Massif, CZE. PMID:26523686

  7. Raman spectroscopic identification of arsenate minerals in situ at outcrops with handheld (532 nm, 785 nm) instruments

    NASA Astrophysics Data System (ADS)

    Culka, Adam; Kindlová, Helena; Drahota, Petr; Jehlička, Jan

    2016-02-01

    Minerals are traditionally identified under field conditions by experienced mineralogists observing the basic physical properties of the samples. Under laboratory conditions, a plethora of techniques are commonly used for identification of the geological phases based on their structural and spectroscopic parameters. In this area, Raman spectrometry has become a useful tool to complement the more widely applied XRD. Today, however, there is an acute need for a technique for unambiguous in situ identification of minerals, within the geological as well as planetary/exobiology realms. With the potential for miniaturization, Raman spectroscopy can be viewed as a practical technique to achieve these goals. Here, for the first time, the successful application of handheld Raman spectrometers is demonstrated to detect and discriminate arsenic phases in the form of earthy aggregates. The Raman spectroscopic analyses of arsenate minerals were performed in situ using two handheld instruments, using 532 and 785 nm excitation. Bukovskýite, kaňkite, parascorodite, and scorodite were identified from Kaňk near Kutná Hora, CZE; kaňkite, scorodite, and zýkaite were identified at the Lehnschafter gallery in an old silver mine at Mikulov near Teplice, Bohemian Massif, CZE.

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

    NASA Astrophysics Data System (ADS)

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

    2010-09-01

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

  9. In-situ Raman spectroscopy of electrically generated species in fullerene thin films

    NASA Astrophysics Data System (ADS)

    Phelan, Siobhan B.; O'Connell, Barry S.; Farrell, Garrett F.; Chambers, Gordon; Byrne, Hugh J.

    2003-03-01

    Organic materials have, in recent decades, been shown to be insulators, semiconductors, or even metallic when doped and the prospect of cheap, easily fabricated devices has attracted much interest. Primitive devices have been demonstrated and yet potentially competitive performance has been limited to polymer light emitting diodes. The recent report that lattice expanded C60 single crystals can be made superconducting, with a transition temperature of 117K, by the injection of charge via a FET type geometry has once again highlighted the potential of C60 in the development of molecular electronic devices. In light of the aforementioned report it is essential that a true understanding of the inter- and intramolecular processes in terms of their contribution to the electronic transport be obtained. In this study the current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behavior and a sharp increase in the device conductivity was observed at relatively low voltages (~2V), at both room and low temperatures (20K). At room temperature the system is seen to collapse, and in situ Raman measurements indicate a solid state reduction of the fullerene thin film to form a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C60 film was seen to sporadically emit white light at randomly localized points analogous to the much documented electroluminescence in single crystals. Moreover the evidence suggests that this highly conducting species maybe similar in nature to a high intensity optically excited species. It is further speculated that the species recently reported in the superconducting lattice expanded C60 single crystals may also be analogous to the highly

  10. RNA Imaging with Multiplexed Error Robust Fluorescence in situ Hybridization

    PubMed Central

    Moffitt, Jeffrey R.; Zhuang, Xiaowei

    2016-01-01

    Quantitative measurements of both the copy number and spatial distribution of large fractions of the transcriptome in single-cells could revolutionize our understanding of a variety of cellular and tissue behaviors in both healthy and diseased states. Single-molecule Fluorescence In Situ Hybridization (smFISH)—an approach where individual RNAs are labeled with fluorescent probes and imaged in their native cellular and tissue context—provides both the copy number and spatial context of RNAs but has been limited in the number of RNA species that can be measured simultaneously. Here we describe Multiplexed Error Robust Fluorescence In Situ Hybridization (MERFISH), a massively parallelized form of smFISH that can image and identify hundreds to thousands of different RNA species simultaneously with high accuracy in individual cells in their native spatial context. We provide detailed protocols on all aspects of MERFISH, including probe design, data collection, and data analysis to allow interested laboratories to perform MERFISH measurements themselves. PMID:27241748

  11. Confocal Raman imaging for cancer cell classification

    NASA Astrophysics Data System (ADS)

    Mathieu, Evelien; Van Dorpe, Pol; Stakenborg, Tim; Liu, Chengxun; Lagae, Liesbet

    2014-05-01

    We propose confocal Raman imaging as a label-free single cell characterization method that can be used as an alternative for conventional cell identification techniques that typically require labels, long incubation times and complex sample preparation. In this study it is investigated whether cancer and blood cells can be distinguished based on their Raman spectra. 2D Raman scans are recorded of 114 single cells, i.e. 60 breast (MCF-7), 5 cervix (HeLa) and 39 prostate (LNCaP) cancer cells and 10 monocytes (from healthy donors). For each cell an average spectrum is calculated and principal component analysis is performed on all average cell spectra. The main features of these principal components indicate that the information for cell identification based on Raman spectra mainly comes from the fatty acid composition in the cell. Based on the second and third principal component, blood cells could be distinguished from cancer cells; and prostate cancer cells could be distinguished from breast and cervix cancer cells. However, it was not possible to distinguish breast and cervix cancer cells. The results obtained in this study, demonstrate the potential of confocal Raman imaging for cell type classification and identification purposes.

  12. Raman imaging of neoplastic cells in suspension

    NASA Astrophysics Data System (ADS)

    Creely, C. M.; Mercadal, S.; Volpe, G.; Soler, M.; Petrov, D. V.

    2006-08-01

    The combination of Raman spectroscopy and Optical Tweezers has been used to trap living cells and collect information about their biochemical state. Cells can continue living in such traps for periods of hours, allowing acquisition of time resolved Raman spectra. However no spatial information can be acquired as the cells continue to rotate and move in the single beam trap. Here we describe the development of Holographic Optical Tweezers (HOT) for the controlled movement of floating cells in order to construct their Raman images. Instead of a single trap, rapidly programmable multiple trapping points can be produced around the periphery of the cells to impede the rotational motion of the cell. By trapping and scanning the cell using HOT relative to a fixed Raman exciting laser, a point by point image of the cell can be constructed. We use an interactive program that permits us to position the trapping points relative to the live image feed we see from the microscope, using point and click. To demonstrate the possibilities of this technique images are shown of floating Jurkat cells.

  13. Raman chemical imaging system for food safety and quality inspection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging technique combines Raman spectroscopy and digital imaging to visualize composition and structure of a target, and it offers great potential for food safety and quality research. In this study, a laboratory-based Raman chemical imaging platform was designed and developed. The i...

  14. Tissue section AFM: In situ ultrastructural imaging of native biomolecules

    PubMed Central

    Graham, Helen K.; Hodson, Nigel W.; Hoyland, Judith A.; Millward-Sadler, Sarah J.; Garrod, David; Scothern, Anthea; Griffiths, Christopher E.M.; Watson, Rachel E.B.; Cox, Thomas R.; Erler, Janine T.; Trafford, Andrew W.; Sherratt, Michael J.

    2010-01-01

    Conventional approaches for ultrastructural high-resolution imaging of biological specimens induce profound changes in bio-molecular structures. By combining tissue cryo-sectioning with non-destructive atomic force microscopy (AFM) imaging we have developed a methodology that may be applied by the non-specialist to both preserve and visualize bio-molecular structures (in particular extracellular matrix assemblies) in situ. This tissue section AFM technique is capable of: i) resolving nm–µm scale features of intra- and extracellular structures in tissue cryo-sections; ii) imaging the same tissue region before and after experimental interventions; iii) combining ultrastructural imaging with complimentary microscopical and micromechanical methods. Here, we employ this technique to: i) visualize the macro-molecular structures of unstained and unfixed fibrillar collagens (in skin, cartilage and intervertebral disc), elastic fibres (in aorta and lung), desmosomes (in nasal epithelium) and mitochondria (in heart); ii) quantify the ultrastructural effects of sequential collagenase digestion on a single elastic fibre; iii) correlate optical (auto fluorescent) with ultrastructural (AFM) images of aortic elastic lamellae. PMID:20144712

  15. In situ Measurement of Pore-Water pH in Anoxic Sediments Using Laser Raman Spectrometry

    NASA Astrophysics Data System (ADS)

    Peltzer, E. T.; Luna, M.; Walz, P. M.; Zhang, X.; Brewer, P. G.

    2010-12-01

    Accurate measurement of the geochemical properties of sediment pore waters is of fundamental importance in ocean geochemistry and microbiology. Recent work has shown that the properties of pore waters can be measured rapidly in situ with a novel Raman based insertion probe (Zhang et al., 2010), and that data obtained from anoxic sediments on in situ dissolved methane concentrations are very different (~30x) than from recovered cores due the large scale degassing that occurs during core recovery (Zhang et al., submitted). Degassing of methane must carry with it via Henry’s Law partioning significant quantities of H2S, which is clearly detectable by smell during sample processing, and thus in situ measurement of H2S is also highly desirable. In practice, dissolved H2S is partitioned between the HS- and H2S species as a function of pH with pKa ~7 for the acid dissociation reaction. Since both species are Raman active full determination of the sulfide system is possible if the relative Raman cross sections are known. The diagenetic equations for these reactions are commonly summarized as: 2CH2O + SO4= ↔ 2HCO3- + H2S CH4 + SO4= ↔ HCO3- + HS- + H2O Three of the major components of these equations, CH4, SO4=, and H2S/HS-, are all observable directly by Raman spectroscopy; but the detection of HCO3- presents a challenge due to its low Raman cross section and thus poor sensitivity. We show that pore water pH, which is a good estimator of HCO3- if total CO2 or alkalinity are known, can be measured by observing the H2S / HS- ratio via the equation: pH = pKa + log([HS-]/[H2S]) thereby fully constraining these equations within a single measurement protocol. The Raman peak for HS- is at 2573 cm-1 and for H2S is at 2592 cm-1; thus the peaks are well separated and may easily be deconvoluted from the observed spectrum. We have determined the relative Raman cross sections by a series of laboratory measurements over a range of pH and by using the definition that when pH = p

  16. A microfabricated scanning confocal optical microscope for in situ imaging

    NASA Astrophysics Data System (ADS)

    Dickensheets, David Lee

    Scanning confocal optical microscopes are well suited for imaging living tissue because of their ability to 'cross section' intact tissue. They are not, however, well suited for imaging tissues in situ. This dissertation describes a new, miniature, mirror scanned, high resolution confocal optical microscope that operates in real time. It is small enough to fit into an endoscope, and may eventually be incorporated into a hypodermic needle. Such a device would provide immediate in-situ tissue assessment at the cellular level and may enable, for example, biopsy without tissue removal. Non-medical applications may include process monitoring and endoscopic inspection. The microfabricated confocal optical scanning microscope, or μCOSM, incorporates single mode optical fiber illumination, silicon torsional scan mirrors, and an off- axis micro diffractive lens. The prototype device is monochromatic, at 633 nm, with a 1.1 mm working distance and 0.25 NA. It achieves a line response of 0.98 μm FWHM, and an axial response of 11.1 μm FWHM. The first part of the dissertation describes the opto- mechanical design of the microscope, which was chosen to be compatible with the microfabrication technologies used for its construction. Then the imaging properties of the off-axis diffractive objective lens are developed, including the aberrations of second and third order which constrain its use. The lens is a surface relief phase grating, and a rigorous electromagnetic analysis is employed to specify the pupil function of the microscope. Then the image forming properties of the μCOSM are derived and compared to experimental results. The second part of the dissertation describes the fabrication of the individual elements of the μCOSM, and their assembly into an imaging instrument. The lens is constructed using electron beam lithography and reactive ion etching of a fused silica substrate. The scanning mirrors for the microscope, which comprise a single crystal silicon plate

  17. Probing Xylan-Specific Raman Bands for Label-Free Imaging Xylan in Plant Cell Wall

    SciTech Connect

    Zeng, Yining; Yarbrough, John M.; Mittal, Ashutosh; Tucker, Melvin P.; Vinzant, Todd; Himmel, Michael E.

    2015-06-15

    Xylan constitutes a significant portion of biomass (e.g. 22% in corn stover used in this study). Xylan is also an important source of carbohydrates, besides cellulose, for renewable and sustainable energy applications. Currently used method for the localization of xylan in biomass is to use fluorescence confocal microscope to image the fluorescent dye labeled monoclonal antibody that specifically binds to xylan. With the rapid adoption of the Raman-based label-free chemical imaging techniques in biology, identifying Raman bands that are unique to xylan would be critical for the implementation of the above label-free techniques for in situ xylan imaging. Unlike lignin and cellulose that have long be assigned fingerprint Raman bands, specific Raman bands for xylan remain unclear. The major challenge is the cellulose in plant cell wall, which has chemical units highly similar to that of xylan. Here we report using xylanase to specifically remove xylan from feedstock. Under various degree of xylan removal, with minimum impact to other major cell wall components, i.e. lignin and cellulose, we have identified Raman bands that could be further tested for chemical imaging of xylan in biomass in situ.

  18. In situ mobile subaquatic archaeometry evaluated by non-destructive Raman microscopy of gemstones lying under impure waters

    NASA Astrophysics Data System (ADS)

    Smith, David C.

    2003-08-01

    A series of laboratory simulations have been made in order to evaluate the credibility of carrying out physico-chemical analysis of cultural heritage items by Raman spectral fingerprinting using a mobile Raman microscope in situ under natural impure water in subaquatic or submarine conditions. Three different kinds of gemstone (zircon, microcline and sodalite) were successively placed under different kinds of impure water into which a low power microscope objective was immersed to eliminate the normal aerial pathway between the objective and the object to be analysed. According to the nature of the impurities (inorganic or organic, dissolved or suspended, transparent or coloured) the results obtained variously gave Raman band intensities stronger than, similar to or weaker than those of spectra obtained without water, i.e. in air. The significant point is that after only minor spectral treatment the less good spectra nevertheless yielded exploitable data with most, if not all, of the key Raman bands being detected. Thus the problems of fluorescence or peak absences under water are of a similar degree of magnitude to the other problems inherent with the Raman spectroscopic technique in aerial conditions, e.g. relative peak intensities varying with crystal orientation; peak positions varying with chemical composition. These results indicate that even if at certain sites of submerged cities or sunken ships, the combination of animal, vegetal, mineral and microbial impurities join together to inhibit or hinder the success of subaquatic or submarine archaeometry, there will certainly be other sites where such activity is indeed credible.

  19. In situ mobile subaquatic archaeometry evaluated by non-destructive Raman microscopy of gemstones lying under impure waters.

    PubMed

    Smith, David C

    2003-08-01

    A series of laboratory simulations have been made in order to evaluate the credibility of carrying out physico-chemical analysis of cultural heritage items by Raman spectral fingerprinting using a mobile Raman microscope in situ under natural impure water in subaquatic or submarine conditions. Three different kinds of gemstone (zircon, microcline and sodalite) were successively placed under different kinds of impure water into which a low power microscope objective was immersed to eliminate the normal aerial pathway between the objective and the object to be analysed. According to the nature of the impurities (inorganic or organic, dissolved or suspended, transparent or coloured) the results obtained variously gave Raman band intensities stronger than, similar to or weaker than those of spectra obtained without water, i.e. in air. The significant point is that after only minor spectral treatment the less good spectra nevertheless yielded exploitable data with most, if not all, of the key Raman bands being detected. Thus the problems of fluorescence or peak absences under water are of a similar degree of magnitude to the other problems inherent with the Raman spectroscopic technique in aerial conditions, e.g. relative peak intensities varying with crystal orientation; peak positions varying with chemical composition. These results indicate that even if at certain sites of submerged cities or sunken ships, the combination of animal, vegetal, mineral and microbial impurities join together to inhibit or hinder the success of subaquatic or submarine archaeometry, there will certainly be other sites where such activity is indeed credible. PMID:12909148

  20. In situ imaging and control of layer-by-layer femtosecond laser thinning of graphene

    NASA Astrophysics Data System (ADS)

    Li, D. W.; Zhou, Y. S.; Huang, X.; Jiang, L.; Silvain, J.-F.; Lu, Y. F.

    2015-02-01

    only realize the large-scale thinning of graphene with atomic layer precision, but also provide in situ, rapid imaging capability of graphene for an accurate assessment of the number of layers. Electronic supplementary information (ESI) available: Raman mapping and AFM images of few-layered graphene; threshold for the fs laser thinning of few-layered graphene. See DOI: 10.1039/c4nr07078j

  1. In Situ Chemical Imaging of Plant Cell Walls Using CARS/SRS Microscopy (Poster)

    SciTech Connect

    Zeng, Y.; Liu, Y. S.; Saar, B. G.; Xie, X. S.; Chen, F.; Dixon, R. A.; Himmel, M. E.; Ding S. Y.

    2009-06-01

    This poster demonstrates coherent anti-Stokes Raman scattering and stimulated Raman scattering of plant cell walls. It includes simultaneous chemical imaging of lignin and cellulose (corn stover) during acidic pretreatment.

  2. Fluorescent In Situ Hybridization in Suspension by Imaging Flow Cytometry.

    PubMed

    Maguire, Orla; Wallace, Paul K; Minderman, Hans

    2016-01-01

    The emergence of imaging flow cytometry (IFC) has brought novel applications exploiting its advantages over conventional flow cytometry and microscopy. One of the new applications is fluorescence in situ hybridization in suspension (FISH-IS). Conventional FISH is a slide-based approach in which the spotlike imagery resulting from hybridization with fluorescently tagged probes is evaluated by fluorescence microscopy. The FISH-IS approach evaluated by IFC enables the evaluation of tens to hundreds of thousands of cells in suspension and the analysis can be automated and standardized diminishing operator bias from the analysis. The high cell number throughput of FISH-IS improves the detection of rare events compared to conventional FISH. The applicability of FISH-IS is currently limited to detection of abnormal quantitative differences of hybridization targets such as occur in numerical chromosome abnormalities, deletions and amplifications.Here, we describe a protocol for FISH-IS using chromosome enumeration probes as an example. PMID:27460240

  3. Characterization of BxPC3-transplanted mice by hyperspectral autofluorescence imaging and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Sawa, Masanori; Andriana, Bibin Bintang; Sato, Hidetoshi

    2014-02-01

    Live subcutaneous tumor grown in nude mouse is studied in situ with hyperspectral autofluorescence imaging and Raman spectroscopy. The purpose of the study is to develop methods for characterization of biochemical changing and of histological type of tumor without labeling. The results show that there are site depending variation in the fluorescence and Raman spectra. At the spot in which calcification is in process, Raman spectra showed a strong and specific band at 957 cm-1 due to PO4 species. The autofluosescence image can prove the histological changes based on the NADH and FAD which are major fluorophores in biological tissues. The hyperspectral image is analyzed with principal component analysis and the reconstructed images successfully depicts a different between necrotic and viable part within living subcutaneous tumor.

  4. Simultaneous imaging of fat crystallinity and crystal polymorphic types by Raman microspectroscopy.

    PubMed

    Motoyama, Michiyo; Ando, Masahiro; Sasaki, Keisuke; Nakajima, Ikuyo; Chikuni, Koichi; Aikawa, Katsuhiro; Hamaguchi, Hiro-O

    2016-04-01

    The crystalline states of fats, i.e., the crystallinity and crystal polymorphic types, strongly influence their physical properties in fat-based foods. Imaging of fat crystalline states has thus been a subject of abiding interest, but conventional techniques cannot image crystallinity and polymorphic types all at once. This article demonstrates a new technique using Raman microspectroscopy for simultaneously imaging the crystallinity and polymorphic types of fats. The crystallinity and β' crystal polymorph, which contribute to the hardness of fat-based food products, were quantitatively visualized in a model fat (porcine adipose tissue) by analyzing several key Raman bands. The emergence of the β crystal polymorph, which generally results in food product deterioration, was successfully imaged by analyzing the whole fingerprint regions of Raman spectra using multivariate curve resolution alternating least squares analysis. The results demonstrate that the crystalline states of fats can be nondestructively visualized and analyzed at the molecular level, in situ, without laborious sample pretreatments. PMID:26593509

  5. Raman chemical imaging technology for food safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging combines Raman spectroscopy and digital imaging to visualize composition and morphology of a target. This technique offers great potential for food safety and quality research. Most commercial Raman instruments perform measurement at microscopic level, and the spatial range ca...

  6. 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

  7. Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method

    PubMed Central

    Tan, Chih-Shan; Chen, Hung-Ying; Chen, Hsueh-Szu; Gwo, Shangjr; Chen, Lih-Juann

    2015-01-01

    For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution. PMID:26333518

  8. Intermediates in the cation reactions in solution probed by an in situ surface enhanced Raman scattering method

    NASA Astrophysics Data System (ADS)

    Tan, Chih-Shan; Chen, Hung-Ying; Chen, Hsueh-Szu; Gwo, Shangjr; Chen, Lih-Juann

    2015-09-01

    For chemical reactions in liquid state, such as catalysis, understanding of dynamical changes is conducive to practical applications. Solvation of copper salts in aqueous solution has implications for life, the environment, and industry. In an ongoing research, the question arises that why the color of aqueous CuCl2 solution changes with solution concentration? In this work, we have developed a convenient and efficient in situ surface enhanced Raman scattering technique to probe the presence of many intermediates, some of them are responsible for color change, in crystallization of aqueous copper chloride solution. The versatility of the novel technique was confirmed in the identification of five intermediates states in the transition from CdS to MoS2 nanowires in solution. The facile in situ method is expected to be widely applicable in probing intermediate states in a variety of chemical reactions in solution.

  9. Tip-enhanced Raman spectroscopy (TERS) for in situ identification of indigo and iron gall ink on paper.

    PubMed

    Kurouski, Dmitry; Zaleski, Stephanie; Casadio, Francesca; Van Duyne, Richard P; Shah, Nilam C

    2014-06-18

    Confirmatory, nondestructive, and noninvasive identification of colorants in situ is of critical importance for the understanding of historical context and for the long-term preservation of cultural heritage objects. Although there are several established techniques for analyzing cultural heritage materials, there are very few analytical methods that can be used for molecular characterization when very little sample is available, and a minimally invasive approach is required. Tip-enhanced Raman spectroscopy (TERS) is a powerful analytical technique whose key features include high mass sensitivity, high spatial resolution, and precise positioning of the tip. In the current proof-of-concept study we utilized TERS to identify indigo dye and iron gall ink in situ on Kinwashi paper. In addition, TERS was used to identify iron gall ink on a historical document with handwritten text dated to the 19th century. We demonstrate that TERS can identify both of these colorants directly on paper. Moreover, vibrational modes from individual components of a complex chemical mixture, iron gall ink, can be identified. To the best of our knowledge, this is the first demonstration of in situ TERS for colorants of artistic relevance directly on historical materials. Overall, this work demonstrates the great potential of TERS as an additional spectroscopic tool for minimally invasive compositional characterization of artworks in situ and opens exciting new possibilities for cultural heritage research. PMID:24848305

  10. Biomedical applications of a new portable Raman imaging probe

    NASA Astrophysics Data System (ADS)

    Sato, Hidetoshi; Tanaka, Takeyuki; Ikeda, Teruki; Wada, Satoshi; Tashiro, Hideo; Ozaki, Yukihiro

    2001-10-01

    This article reports the outline of a new portable Raman imaging probe and its applications. This probe may be the smallest and lightest Raman imaging probe in the world. It is equipped with an interchangeable long-working distance microscope objective lens. The irradiation area is about 45 and 90 μm and the spatial resolution is 1 μm. In the present study, the Raman imaging probe was used to obtain a Raman image of diamond particles and a Raman mapping of carotenoid in Euglena.

  11. Practical in-situ determination of ortho-para hydrogen ratios via fiber-optic based Raman spectroscopy

    SciTech Connect

    Sutherland, Liese -Marie; Knudson, James N.; Mocko, Michal; Renneke, Richard M.

    2015-12-17

    An experiment was designed and developed to prototype a fiber-optic-based laser system, which measures the ratio of ortho-hydrogen to para-hydrogen in an operating neutron moderator system at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source. Preliminary measurements resulted in an ortho to para ratio of 3.06:1, which is within acceptable agreement with the previously published ratio. As a result, the successful demonstration of Raman Spectroscopy for this measurement is expected to lead to a practical method that can be applied for similar in-situ measurements at operating neutron spallation sources.

  12. Practical in-situ determination of ortho-para hydrogen ratios via fiber-optic based Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Sutherland, Liese-Marie; Knudson, James N.; Mocko, Michal; Renneke, Richard M.

    2016-02-01

    An experiment was designed and developed to prototype a fiber-optic-based laser system, which measures the ratio of ortho-hydrogen to para-hydrogen in an operating neutron moderator system at the Los Alamos Neutron Science Center (LANSCE) spallation neutron source. Preliminary measurements resulted in an ortho to para ratio of 3.06:1, which is within acceptable agreement with the previously published ratio. The successful demonstration of Raman Spectroscopy for this measurement is expected to lead to a practical method that can be applied for similar in-situ measurements at operating neutron spallation sources.

  13. Ion transport and electrochemical tuning of Fermi level in single-wall carbon nanotube probed by in situ Raman scattering

    NASA Astrophysics Data System (ADS)

    Gupta, S.; Robertson, J.

    2006-10-01

    In situ Raman spectroscopy technique was employed to investigate the ion transport process and to determine the concomitant electrochemical tuning of Fermi level in single-wall carbon nanotube. The variation of structural bonding in single-wall carbon nanotube bundle dipped in aqueous alkaline earth halide electrolyte such as CaCl2 with electrochemical biasing was monitored. It is because Raman can detect changes in C-C bond length through radial breathing mode at ˜184cm-1 that varies inversely with the nanotube diameter and the G band at ˜1590cm-1 that varies with the axial bond length. Consistent reversible and substantial variations in Raman intensity of both the modes induced by electrode potential point at the fine and continuous tuning (alternatively, emptying/depleting or filling) of the specific bonding and antibonding states. Qualitatively, the results were explained in terms of changes in the energy gaps between the one-dimensional van Hove singularities present in the electron density of states arising possibly due to the alterations in the overlap integral of π bonds between the p orbitals of the adjacent carbon atoms. We estimated the extent of variation of the absolute potential of the Fermi level and overlap integral (γ0) between the nearest-neighbor carbon atoms from modeling the electrochemical potential dependence of Raman intensity. Observations also suggest that the work function of the tube is larger for the metallic nanotubes in contrast to the simultaneously present semiconducting nanotubes.

  14. Rapid in situ detection of street samples of drugs of abuse on textile substrates using microRaman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ali, Esam M. A.; Edwards, Howell G. M.; Scowen, Ian J.

    2011-10-01

    Trace amounts of street samples of cocaine hydrochloride and N-methyl-3,4-methylenedioxy-amphetamine (MDMA) on natural and synthetic textiles were successfully detected in situ using confocal Raman microscopy. The presence of some excipient bands in the spectra of the drugs did not prevent the unambiguous identification of the drugs. Raman spectra of the drugs were readily obtained without significant interference from the fibre substrates. Interfering bands arising from the fibre natural or synthetic polymer structure and/or dye molecules did not overlap with the characteristic Raman bands of the drugs. If needed, interfering bands could be successfully removed by spectral subtraction. Also, Raman spectra could be acquired from drug particles trapped between the fibres of highly fluorescent textile specimens. The total acquisition time of the spectra of the drug particles was 90 s accomplished non-destructively and without detachment from their substrates. Sample preparation was not required and spectra of the drugs could be obtained non-invasively preserving the integrity of the evidential material for further analysis.

  15. Raman shifts and in situ TEM electrical degradation of electron-irradiated monolayer MoS2

    NASA Astrophysics Data System (ADS)

    Parkin, William M.; Balan, Adrian; Liang, Liangbo; Masih Das, Paul; Lamparski, Michael; Naylor, Carl; Rodriguez-Manzo, Julio A.; Johnson, Alan T.; Meunier, Vincent; Drndic, Marija

    We report how the presence of electron-beam-induced vacancies affects first-order Raman modes and correlate this effect with the evolution of in situ TEM two-terminal conductivity of monolayer MoS2 under electron irradiation. We observe a redshift in the E' Raman peak and a less pronounced blueshift in the A'1 peak with increasing electron dose. Using energy-dispersive X-ray spectroscopy, we show that irradiation causes partial removal of sulfur and correlate the dependence of the Raman peak shifts with S vacancy density (a few percent), which is confirmed by first-principles density functional theory calculations. Insitu device current measurements show exponential decrease in channel current upon irradiation. Our analysis demonstrates that the observed frequency shifts are intrinsic properties of the defective systems and that Raman spectroscopy can be used as a quantitative diagnostic tool to accurately characterize MoS2-based transport channels. This work was supported by the NIH Grant R21HG004767 and NIH Grant R21HG007856. Theoretical work at RPI was supported the NYSTAR program C080117 and the Office of Naval Research. C.H.N. and A.T.C.J. acknowledge support from UES/Air Force Research Lab.

  16. 3D imaging of enzymes working in situ.

    PubMed

    Jamme, F; Bourquin, D; Tawil, G; Viksø-Nielsen, A; Buléon, A; Réfrégiers, M

    2014-06-01

    Today, development of slowly digestible food with positive health impact and production of biofuels is a matter of intense research. The latter is achieved via enzymatic hydrolysis of starch or biomass such as lignocellulose. Free label imaging, using UV autofluorescence, provides a great tool to follow one single enzyme when acting on a non-UV-fluorescent substrate. In this article, we report synchrotron DUV fluorescence in 3-dimensional imaging to visualize in situ the diffusion of enzymes on solid substrate. The degradation pathway of single starch granules by two amylases optimized for biofuel production and industrial starch hydrolysis was followed by tryptophan autofluorescence (excitation at 280 nm, emission filter at 350 nm). The new setup has been specially designed and developed for a 3D representation of the enzyme-substrate interaction during hydrolysis. Thus, this tool is particularly effective for improving knowledge and understanding of enzymatic hydrolysis of solid substrates such as starch and lignocellulosic biomass. It could open up the way to new routes in the field of green chemistry and sustainable development, that is, in biotechnology, biorefining, or biofuels. PMID:24796213

  17. Molecular imaging with surface-enhanced Raman spectroscopy nanoparticle reporters

    PubMed Central

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

    2013-01-01

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

  18. 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.

  19. Observing Metal-Catalyzed Chemical Reactions in Situ Using Surface-Enhanced Raman Spectroscopy on Pd–Au Nanoshells

    PubMed Central

    Heck, Kimberly N.; Janesko, Benjamin G.; Scuseria, Gustavo E.

    2016-01-01

    Insight into the nature of transient reaction intermediates and mechanistic pathways involved in heterogeneously catalyzed chemical reactions is obtainable from a number of surface spectroscopic techniques. Carrying out these investigations under actual reaction conditions is preferred but remains challenging, especially for catalytic reactions that occur in water. Here, we report the direct spectroscopic study of the catalytic hydrodechlorination of 1,1-dichloroethene in H2O using surface-enhanced Raman spectroscopy (SERS). With Pd islands grown on Au nanoshell films, this reaction can be followed in situ using SERS, exploiting the high enhancements and large active area of Au nanoshell SERS substrates, the transparency of Raman spectroscopy to aqueous solvents, and the catalytic activity enhancement of Pd by the underlying Au metal. The formation and subsequent transformation of several adsorbate species was observed. These results provide the first direct evidence of the room-temperature catalytic hydrodechlorination of a chlorinated solvent, a potentially important pathway for groundwater cleanup, as a sequence of dechlorination and hydrogenation steps. More broadly, the results highlight the exciting prospects of studying catalytic processes in water in situ, like those involved in biomass conversion and proton-exchange membrane fuel cells. PMID:19554693

  20. Raman microspectroscopy: a powerful analytic and imaging tool in petrology and geochemistry

    NASA Astrophysics Data System (ADS)

    Beyssac, O.

    2013-12-01

    Raman microspectroscopy is a vibrational spectroscopy based on the inelastic scattering of light interacting with molecules. This technique has benefited from recent developments in spectral and spatial resolution as well as sensitivity which make it widely used in Geosciences. A very attractive aspect of Raman spectroscopy is that it does not require any complex sample preparation. In addition, Raman imaging is now a routine and reliable technique which makes it competitive with SEM-EDS mapping for mineral mapping for instance. Raman microspectroscopy is a complementary technique to SEM, EMP, SIMS... as it can provide not only information on mineral chemistry, but overall on mineral structure. Raman Microspectroscopy is for instance the best in situ technique to distinguish mineral polymorphs. In addition the sensitivity of RM to mineral structure is extremely useful to study accessory minerals like oxides or sulphides as well as graphitic carbons. A brief presentation of the analytical capabilities of modern Raman spectroscopy will be presented. Then recent applications of RM in petrological and geochemical problems will be reviewed, including Raman imaging. The advantages and disadvantages of this technique compared to other micro-analytic tools will be discussed.

  1. In vivo Coherent Raman Imaging for Neuroscience Applications

    NASA Astrophysics Data System (ADS)

    Cote, Daniel

    2010-08-01

    The use of coherent Raman imaging is described for applications in neuroscience. Myelin imaging of the spinal cord can be performed with Raman imaging through the use of the vibration in carbon-hydrogen bonds, dominant in lipids. First, we demonstrate in vivo histomorphometry in live animal for characterization of myelin-related nervous system pathologies. This is used to characterize spinal cord health during multiple sclerosis. Second, Raman spectroscopy of tissue is discussed. We discuss the challenges that live animal imaging brings, together with important aspects of coherent Raman imaging in tissue.

  2. 671-nm microsystem diode laser based on portable Raman sensor device for in-situ identification of meat spoilage

    NASA Astrophysics Data System (ADS)

    Sowoidnich, Kay; Schmidt, Heinar; Schwägele, Fredi; Kronfeldt, Heinz-Detlef

    2011-05-01

    Based on a miniaturized optical bench with attached 671 nm microsystem diode laser we present a portable Raman system for the rapid in-situ characterization of meat spoilage. It consists of a handheld sensor head (dimensions: 210 x 240 x 60 mm3) for Raman signal excitation and collection including the Raman optical bench, a laser driver, and a battery pack. The backscattered Raman radiation from the sample is analyzed by means of a custom-designed miniature spectrometer (dimensions: 200 x 190 x 70 mm3) with a resolution of 8 cm-1 which is fiber-optically coupled to the sensor head. A netbook is used to control the detector and for data recording. Selected cuts from pork (musculus longissimus dorsi and ham) stored refrigerated at 5 °C were investigated in timedependent measurement series up to three weeks to assess the suitability of the system for the rapid detection of meat spoilage. Using a laser power of 100 mW at the sample meat spectra can be obtained with typical integration times of 5 - 10 seconds. The complex spectra were analyzed by the multivariate statistical tool PCA (principal components analysis) to determine the spectral changes occurring during the storage period. Additionally, the Raman data were correlated with reference analyses performed in parallel. In that way, a distinction between fresh and spoiled meat can be found in the time slot of 7 - 8 days after slaughter. The applicability of the system for the rapid spoilage detection of meat and other food products will be discussed.

  3. Development of microfluidic devices for in situ investigation of cells using surface-enhanced Raman spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Ho, Yu-Han; Galvan, Daniel D.; Yu, Qiuming

    2016-03-01

    Surface-enhanced Raman spectroscopy (SERS) has immerged as a power analytical and sensing technique for many applications in biomedical diagnosis, life sciences, food safety, and environment monitoring because of its molecular specificity and high sensitivity. The inactive Raman scattering of water molecule makes SERS a suitable tool for studying biological systems. Microfluidic devices have also attracted a tremendous interest for the aforementioned applications. By integrating SERS-active substrates with microfluidic devices, it offers a new capability for in situ investigation of biological systems, their dynamic behaviors, and response to drugs or microenvironment changes. In this work, we designed and fabricated a microfluidic device with SERS-active substrates surrounding by cell traps in microfluidic channels for in situ study of live cells using SERS. The SERS-active substrates are quasi-3D plasmonic nanostructure array (Q3D-PNA) made in h-PDMS/PMDS with physically separated gold film with nanoholes op top and gold nanodisks at the bottom of nanowells. 3D finite-difference time-domain (3D-FDTD) electromagnetic simulations were performed to design Q3D-PNAs with the strongest local electric fields (hot spots) at the top or bottom water/Au interfaces for sensitive analysis of cells and small components, respectively. The Q3D-PNAs with the hot spots on top and bottom were placed at the up and down stream of the microfluidic channel, respectively. Each Q3D-PNA pattern was surrounded with cell trapping structures. The microfluidic device was fabricated via soft lithography. We demonstrated that normal (COS-7) and cancer (HpeG2) cells were captured on the Q3D-PNAs and investigated in situ using SERS.

  4. Real-Time and in Situ Monitoring of Pesticide Penetration in Edible Leaves by Surface-Enhanced Raman Scattering Mapping.

    PubMed

    Yang, Tianxi; Zhang, Zhiyun; Zhao, Bin; Hou, Ruyan; Kinchla, Amanda; Clark, John M; He, Lili

    2016-05-17

    Understanding of the penetration behaviors of pesticides in fresh produce is of great significance for effectively applying pesticides and minimizing pesticide residues in food. There is lack, however, of an effective method that can measure pesticide penetration. Herein, we developed a novel method for real-time and in situ monitoring of pesticide penetration behaviors in spinach leaves based on surface-enhanced Raman scattering (SERS) mapping. Taking advantage of penetrative gold nanoparticles (AuNPs) as probes to enhance the internalized pesticide signals in situ, we have successfully obtained the internal signals from thiabendazole, a systemic pesticide, following its penetration into spinach leaves after removing surface pesticide residues. Comparatively, ferbam, a nonsystemic pesticide, did not show internal signals after removing surface pesticide residues, demonstrating its nonsystemic behavior. In both cases, if the surface pesticides were not removed, copenetration of both AuNPs and pesticides was observed. These results demonstrate a successful application of SERS as an effective method for measuring pesticides penetration in fresh produce in situ. The information obtained could provide useful guidance for effective and safe applications of pesticides on plants. PMID:27099952

  5. In-situ imaging of creep cavities by synchrotron microradiography

    SciTech Connect

    Dobbyn, R.C.; Fields, R.J. ); Farris, J.; Harlow, D.G.; Delph, T.J. )

    1989-05-01

    The long term, high temperature failure mechanism for most polycrystalline metals and ceramics is creep cavitation. Small voids or cavities have been observed to nucleate and grow on stressed grain boundaries. Eventually, so many of the boundaries are covered by cavities that fracture occurs. Many theories have been proposed to predict the details of cavity nucleation and growth and this is still an area of current theoretical interest. Experiments designed to evaluate these theories have mainly compared predicted times-to-fracture with those observed in traditional polycrystalline creep specimens. One interesting approach compared the density change in specimens from interrupted tests with that predicted from theory. There have often been large discrepancies among the various theories and the above observations. More recently cryogenic fracturing followed by scanning electron microscopy, small angle neutron scattering (SANS), and quantitative metallographic image analysis coupled with appropriate stereology have been used to follow the size distribution development in time. There are more direct means of evaluating the theories of cavity nucleation and growth than comparison with time-to-fracture. Most of the experiments have been performed on polycrystals while the theories can most readily be applied to a single boundary. The stress acting on a particular grain boundary in a polycrystal is, in general, not known due to grain boundary sliding and load shedding. To address this problem, copper bicrysatl experiments have been performed in the presented research. While this approach permits evaluation of the stress dependence of the times-to-fracture, it has now proven to be easy to study the cavity growth rate or spacial distribution on the boundary. The authors have now overcome this drawback by imaging individual cavities in-situ using monochromatic synchrotron radiation (SR) microradiography.

  6. Confocal Raman Imaging of Polymeric Materials

    NASA Astrophysics Data System (ADS)

    Schmidt, Ute; Müller, Jörg; Koenen, Joachim

    Polymers play an essential role in modern materials science. Due to the wide variety of mechanical and chemical properties of polymers, they are used in almost every field of application and are still a dynamic area in the development of new materials with demanding requirements. Raman spectroscopy is one of the standard characterization techniques used to uniquely determine the chemical composition of a polymer. Modern materials, however, are generally heterogeneous, in which various chemical components or polymorphs of the same chemical species can be present in a very small sample volume. For the analysis of such heterogeneous materials, the combination of Raman spectroscopy with confocal microscopy delivers information about the spatial distribution of the various chemical species with a resolution down to 200 nm. The aim of this contribution is to demonstrate the power of confocal Raman imaging for the characterization of heterogeneous polymeric materials. The first section will deal with polymorphs of polypropylene in polymer films, followed by the nondestructive analysis of polymer blends. A later section will deal with multi-layer polymer coatings and paints and finally various additives to polymer matrices will be discussed.

  7. Using Raman spectroscopy and SERS for in situ studies of rhizosphere bacteria

    NASA Astrophysics Data System (ADS)

    Polisetti, Sneha; Baig, Nameera; Bible, Amber; Morrell-Falvey, Jennifer; Doktycz, Mitchel; Bohn, Paul W.

    2015-08-01

    Bacteria colonize plant roots to form a symbiotic relationship with the plant and can play in important role in promoting plant growth. Raman spectroscopy is a useful technique to study these bacterial systems and the chemical signals they utilize to interact with the plant. We present a Raman study of Pantoea YR343 that was isolated from the rhizosphere of Populus deltoides (Eastern Cottonwood). Pantoea sp. YR343 produce yellowish carotenoid pigment that play a role in protection against UV radiation, in the anti-oxidative pathways and in membrane fluidity. Raman spectroscopy is used to non-invasively characterize the membrane bound carotenoids. The spectra collected from a mutant strain created by knocking out the crtB gene that encodes a phytoene synthase responsible for early stage of carotenoid biosynthesis, lack the carotenoid peaks. Surface Enhanced Raman Spectroscopy is being employed to detect the plant phytoharmone indoleacetic acid that is synthesized by the bacteria. This work describes our recent progress towards utilizing Raman spectroscopy as a label free, non-destructive method of studying plant-bacteria interactions in the rhizosphere.

  8. In-SITU, Time-resolved Raman Spectro-micro-topography of an Operating Lithium Ion Battery

    NASA Technical Reports Server (NTRS)

    Luo, Yu; Cai, Wen-Bin; Xing, Xue-Kun; Scherson, Daniel A.

    2003-01-01

    A Raman microscope has been coupled to a computer-controlled, two-dimensional linear translator attached to a custom-designed, sealed optical chamber to allow in situ acquisition of space-, and time-resolved spectra of an operating thin graphite/LiCoO2 Li-ion battery. This unique arrangement made it possible to collect continuously series of Raman spectra from a sharply defined edge of the battery exposing the anode (A), separator (S), and cathode (C), during charge and discharge, while the device was moved back and forth under the fixed focused laser beam along an axis normal to the layered A/S/C plane. Clear spectral evidence was obtained for changes in the amount of Li(+) within particles of graphite in the anode, and, to a lesser extent, of LiCoO2 in the cathode, during battery discharge both as a function of position and time. Analysis of time-resolved Raman spectro-micro-topography (SMT) measurements of the type described in this work are expected to open new prospects for assessing the validity of theoretical models aimed at simulating the flow of Li(+) within Li-ion batteries under operating conditions.

  9. Silver nanoparticles doped agarose disk: highly sensitive surface-enhanced Raman scattering substrate for in situ analysis of ink dyes.

    PubMed

    Raza, Ali; Saha, Basudeb

    2013-12-10

    Raman spectroscopy is a preferred analytical tool for forensic trace analysis due to its non-invasive nature. This technique has been utilized in examination of organic colorants present in fibers and ink, but high fluorescent nature of these compounds is a problem. In the present study, silver-doped agarose gel disk, having property of quenching fluorescence and enhancing Raman signals, is found to be effective as surface-enhanced Raman scattering (SERS) substrates for analysis of rhodamine 6G (Rh 6G) and crystal violet (CV) dyes. As-prepared and well characterized by UV, TEM-EDAX and XRD techniques, the investigated silver-doped agarose gel disk proves to have minimal invasive as confirmed by the ATR-FTIR method and effective for in situ SERS analysis of blue and red ballpoint ink. The disk is stable upon storage and hence can be re-used and re-examined. The present method offers new possibilities in trace forensic analysis with minimal destruction. PMID:24314497

  10. Multiferroic CuCrO₂ under high pressure: In situ X-ray diffraction and Raman spectroscopic studies

    SciTech Connect

    Garg, Alka B. Mishra, A. K.; Pandey, K. K.; Sharma, Surinder M.

    2014-10-07

    The compression behavior of delafossite compound CuCrO₂ has been investigated by in situ x-ray diffraction (XRD) and Raman spectroscopic measurements up to 23.2 and 34 GPa, respectively. X-ray diffraction data show the stability of ambient rhombohedral structure up to ~23 GPa. Material shows large anisotropy in axial compression with c-axis compressibility, κ{sub c} = 1.26 × 10⁻³(1) GPa⁻¹ and a-axis compressibility, κ{sub a} = 8.90 × 10⁻³(6) GPa⁻¹. Our XRD data show an irreversible broadening of diffraction peaks. Pressure volume data when fitted to 3rd order Birch-Murnaghan equation of state give the value of bulk modulus, B₀ = 156.7(2.8) GPa with its pressure derivative, B₀{sup ’} as 5.3(0.5). All the observed vibrational modes in Raman measurements show hardening with pressure. Appearance of a new mode at ~24 GPa indicates the structural phase transition in the compound. Our XRD and Raman results indicate that CuCrO{sub 2} may be transforming to an ordered rocksalt type structure under compression.

  11. Resonance Raman spectroscopy as an in situ probe for monitoring catalytic events in a Ru-porphyrin mediated amination reaction.

    PubMed

    Zardi, Paolo; Gallo, Emma; Solan, Gregory A; Hudson, Andrew J

    2016-05-10

    Resonance Raman microspectroscopy has been widely used to study the structure and dynamics of porphyrins and metal complexes containing the porphyrin ligand. Here, we have demonstrated that the same technique can be adapted to examine the mechanism of a homogeneously-catalysed reaction mediated by a transition-metal-porphyrin complex. Previously it has been challenging to study this type of reaction using in situ spectroscopic monitoring due to the low stability of the reaction intermediates and elevated-temperature conditions. We have made a straightforward modification to the sample stage on a microscope for time-lapsed Raman microspectroscopy from reaction mixtures in these media. The allylic amination of unsaturated hydrocarbons by aryl azides, which can be catalysed by a ruthenium-porphyrin complex, has been used as an illustrative example of the methodology. The mechanism of this particular reaction has been studied previously using density-functional theory and kinetic approaches. The Raman measurements support the mechanism proposed in the earlier publications by providing the first experimental verification of a precursor reaction complex between the aryl azide and the ruthenium metal ion, and evidence for the formation of a mono-imido intermediate complex under conditions of high concentration of the reactant olefin. PMID:27070335

  12. Improving the Detection Limit in a Capillary Raman System for In Situ Gas Analysis by Means of Fluorescence Reduction

    PubMed Central

    Rupp, Simone; Off, Andreas; Seitz-Moskaliuk, Hendrik; James, Timothy M.; Telle, Helmut H.

    2015-01-01

    Raman spectroscopy for low-pressure or trace gas analysis is rather challenging, in particular in process control applications requiring trace detection and real-time response; in general, enhancement techniques are required. One possible enhancement approach which enjoys increasing popularity makes use of an internally-reflective capillary as the gas cell. However, in the majority of cases, such capillary systems were often limited in their achievable sensitivity by a significant fluorescence background, which is generated as a consequence of interactions between the laser light and optical glass components in the setup. In order to understand and counteract these problems we have investigated a range of fluorescence-reducing measures, including the rearrangement of optical elements, and the replacement of glass components—including the capillary itself—by metal alternatives. These studies now have led to a capillary setup in which fluorescence is practically eliminated and substantial signal enhancement over standard Raman setups is achieved. With this improved (prototype) setup, detection limits of well below 1 mbar could be obtained in sub-second acquisition times, demonstrating the potential of capillary Raman spectroscopy for real-time, in situ gas sensing and process control applications, down to trace level concentrations. PMID:26378545

  13. In situ identification of crystal facet-mediated chemical reactions on tetrahexahedral gold nanocrystals using surface-enhanced Raman spectroscopy.

    PubMed

    Lang, Xiufeng; You, Tingting; Yin, Penggang; Tan, Enzhong; Zhang, Yan; Huang, Yifan; Zhu, Hongping; Ren, Bin; Guo, Lin

    2013-11-28

    Direct monitoring of a metal-catalyzed reaction by surface-enhanced Raman scattering (SERS) is always a challenging issue as it needs bifunctional metal structures that have plasmonic properties and also act as catalysts. Here we demonstrate that the tetrahexahedral (THH) gold nanocrystals (Au NCs) with exposed {520} facets give highly enhanced Raman signals from molecules at the interface, permitting in situ observation of chemical transformation from para-aminothiophenol (PATP) to 4,4'-dimercaptoazobenzene (DMAB). The origin of the intense SERS signals of DMAB is carefully investigated based on the comparison of the SERS spectra of PATP obtained with both the THH Au NCs and the Au nanospheres with the exposed {111} facets. It is elucidated that the high-index {520} facet rather than the localized surface plasmons of the THH Au NCs plays a key role in producing a high yield of the product DMAB which is accompanied by the selective enhancement of the characteristic Raman signals. PMID:24121935

  14. Improving the Detection Limit in a Capillary Raman System for In Situ Gas Analysis by Means of Fluorescence Reduction.

    PubMed

    Rupp, Simone; Off, Andreas; Seitz-Moskaliuk, Hendrik; James, Timothy M; Telle, Helmut H

    2015-01-01

    Raman spectroscopy for low-pressure or trace gas analysis is rather challenging, in particular in process control applications requiring trace detection and real-time response; in general, enhancement techniques are required. One possible enhancement approach which enjoys increasing popularity makes use of an internally-reflective capillary as the gas cell. However, in the majority of cases, such capillary systems were often limited in their achievable sensitivity by a significant fluorescence background, which is generated as a consequence of interactions between the laser light and optical glass components in the setup. In order to understand and counteract these problems we have investigated a range of fluorescence-reducing measures, including the rearrangement of optical elements, and the replacement of glass components--including the capillary itself--by metal alternatives. These studies now have led to a capillary setup in which fluorescence is practically eliminated and substantial signal enhancement over standard Raman setups is achieved. With this improved (prototype) setup, detection limits of well below 1 mbar could be obtained in sub-second acquisition times, demonstrating the potential of capillary Raman spectroscopy for real-time, in situ gas sensing and process control applications, down to trace level concentrations. PMID:26378545

  15. 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.

  16. In-Situ Lake Bio-Geochemistry Using Laser Raman Spectroscopy and Optrode Sensing

    NASA Astrophysics Data System (ADS)

    Sobron, P.; Sanz, A.; Thompson, C.; Cabrol, N.; Planetary Lake Lander Project Team

    2014-06-01

    We have used LRS for characterizing the organic content of a lake through real-time, in-situ analyses and through lab analyses of returned samples. β-carotene and fatty acids (triglycerides) were identified as major components of the organic samples.

  17. In situ monitoring of powder blending by non-invasive Raman spectrometry with wide area illumination.

    PubMed

    Allan, Pamela; Bellamy, Luke J; Nordon, Alison; Littlejohn, David; Andrews, John; Dallin, Paul

    2013-03-25

    A 785nm diode laser and probe with a 6mm spot size were used to obtain spectra of stationary powders and powders mixing at 50rpm in a high shear convective blender. Two methods of assessing the effect of particle characteristics on the Raman sampling depth for microcrystalline cellulose (Avicel), aspirin or sodium nitrate were compared: (i) the information depth, based on the diminishing Raman signal of TiO(2) in a reference plate as the depth of powder prior to the plate was increased, and (ii) the depth at which a sample became infinitely thick, based on the depth of powder at which the Raman signal of the compound became constant. The particle size, shape, density and/or light absorption capability of the compounds were shown to affect the "information" and "infinitely thick" depths of individual compounds. However, when different sized fractions of aspirin were added to Avicel as the main component, the depth values of aspirin were the same and matched that of the Avicel: 1.7mm for the "information" depth and 3.5mm for the "infinitely thick" depth. This latter value was considered to be the minimum Raman sampling depth when monitoring the addition of aspirin to Avicel in the blender. Mixing profiles for aspirin were obtained non-invasively through the glass wall of the vessel and could be used to assess how the aspirin blended into the main component, identify the end point of the mixing process (which varied with the particle size of the aspirin), and determine the concentration of aspirin in real time. The Raman procedure was compared to two other non-invasive monitoring techniques, near infrared (NIR) spectrometry and broadband acoustic emission spectrometry. The features of the mixing profiles generated by the three techniques were similar for addition of aspirin to Avicel. Although Raman was less sensitive than NIR spectrometry, Raman allowed compound specific mixing profiles to be generated by studying the mixing behaviour of an aspirin

  18. A Microfluidic Bioreactor with in Situ SERS Imaging for the Study of Controlled Flow Patterns of Biofilm Precursor Materials

    PubMed Central

    Paquet-Mercier, François; Aznaveh, Nahid Babaei; Safdar, Muhammad; Greener, Jesse

    2013-01-01

    A microfluidic bioreactor with an easy to fabricate nano-plasmonic surface is demonstrated for studies of biofilms and their precursor materials via Surface Enhanced Raman Spectroscopy (SERS). The system uses a novel design to induce sheath flow confinement of a sodium citrate biofilm precursor stream against the SERS imaging surface to measure spatial variations in the concentration profile. The unoptimised SERS enhancement was approximately 2.5 × 104, thereby improving data acquisition time, reducing laser power requirements and enabling a citrate detection limit of 0.1 mM, which was well below the concentrations used in biofilm nutrient solutions. The flow confinement was observed by both optical microscopy and SERS imaging with good complementarity. We demonstrate the new bioreactor by growing flow-templated biofilms on the microchannel wall. This work opens the way for in situ spectral imaging of biofilms and their biochemical environment under dynamic flow conditions. PMID:24172286

  19. Mapping Li(+) Concentration and Transport via In Situ Confocal Raman Microscopy.

    PubMed

    Forster, Jason D; Harris, Stephen J; Urban, Jeffrey J

    2014-06-01

    We demonstrate confocal Raman microscopy as a general, nonperturbative tool to measure spatially resolved lithium ion concentrations in liquid electrolytes. By combining this high-spatial-resolution technique with a simple microfluidic device, we are able to measure the diffusion coefficient of lithium ions in dimethyl carbonate in two different concentration regimes. Because lithium ion transport plays a key role in the function of a variety of electrochemical devices, quantifying and visualizing this process is crucial for understanding device performance. This method for detecting lithium ions should be immediately useful in the study of lithium-ion-based devices, ion transport in porous media, and at electrode-electrolyte interfaces, and the analytical framework is useful for any system exhibiting a concentration-dependent Raman spectrum. PMID:26273887

  20. In Situ Raman Spectroscopic Study of the Diffusion Coefficients and Solubility:Indicates to Carbon Dioxide Injection into Hexadecane

    NASA Astrophysics Data System (ADS)

    Wu, Dan; Lu, Wanjun

    2015-04-01

    Injecting CO2 into lean-oil reservoirs is not only a way to geological storage but also enhanced oil recovery. In the secondary displacements of oil reservoir by CO2-injection, diffusion coefficients and solubility of CO2 are key parameters to calculate the volume of CO2 injected and the time to achieve the desired viscosity in the numerical simulation. Unfortunately, the experimental data on the CO2 diffusion coefficient and solubility in liquid hydrocarbons under high pressure conditions are scarce. Hexadecane has properties similar to the average properties of Brazilian heavy oil. Experimental data on the diffusion coefficients and solubility of CO2 in hexadecane were reviewed by Nieuwoudt and Rand (2002), Rincon and Trejo (2001) and Breman et al (1994), indicating that the data in the literature were limited at relatively low temperatures and/or low pressures. In this paper, the diffusion coefficients of carbon dioxide in hexadecane at different temperature and pressure were determined with in situ Raman spectroscopy. A model was established to describe relationship among diffusion coefficients, temperature, and pressure. The solubility of CO2 in hexadecane was obtained from 298.15 to 473.15 K and 10 to 45 MPa. The experimental results show that:(1) Solubility of CO2 decreases with increasing temperature.(2) Increasing pressure increases the CO2 solubility. in terms of the degree of influence,100K is similar with 10MPa.(3) Diffusion coefficients of CO2 increases with increasing temperature. (4) Increasing pressure decreases the CO2 diffusion coefficients, whereas the pressure effect on CO2 diffusion coefficients is very weak. Compared with traditional sampling and analytical methods, the advantages of our method include: (1) the use of in situ Raman signals for solubility measurements eliminates possible uncertainty caused by sampling and ex situ analysis. (2) it is simple and efficient, and (3) high-pressure data can be obtained safely.

  1. Pressure Induced Phase Transitions In SmVO4: An In-Situ Raman Study

    NASA Astrophysics Data System (ADS)

    Patel, Nishant N.; Garg, Alka B.; Meenakshi, S.; Pandey, K. K.; Wani, B. N.; Sharma, S. M.

    2010-12-01

    High pressure room temperature Raman investigation on SmVO4 was carried out up to 19 GPa. The ambient zircon phase was observed to remain stable up to 5.8 GPa. At higher pressure two structural phase transitions were observed at 6.8 GPa and 15.9 GPa respectively. The second phase transition was found to be reversible whereas the intermediate phase was retained on complete pressure release.

  2. Pressure Induced Phase Transitions In SmVO{sub 4}: An In-Situ Raman Study

    SciTech Connect

    Patel, Nishant N.; Garg, Alka B.; Meenakshi, S.; Pandey, K. K.; Sharma, S. M.; Wani, B. N.

    2010-12-01

    High pressure room temperature Raman investigation on SmVO{sub 4} was carried out up to 19 GPa. The ambient zircon phase was observed to remain stable up to 5.8 GPa. At higher pressure two structural phase transitions were observed at 6.8 GPa and 15.9 GPa respectively. The second phase transition was found to be reversible whereas the intermediate phase was retained on complete pressure release.

  3. Wide-Field Raman Imaging of Dental Lesions

    PubMed Central

    Yang, Shan; Li, Bolan; Akkus, Anna; Akkus, Ozan; Lang, Lisa

    2014-01-01

    Detection of dental caries at the onset remains as a great challenge in dentistry. Raman spectroscopy could be successfully applied towards detecting caries since it is sensitive to the amount of the Raman active mineral crystals, the most abundant component of enamel. Effective diagnosis requires full examination of a tooth surface via a Raman mapping. Point-scan Raman mapping is not clinically relevant (feasible) due to lengthy data acquisition time. In this work, a wide-field Raman imaging system was assembled based on a high-sensitivity 2D CCD camera for imaging the mineralization status of teeth with lesions. Wide-field images indicated some lesions to be hypomineralized and others to be hypermineralized. The observations of wide-field Raman imaging were in agreement with point-scan Raman mapping. Therefore, sound enamel and lesions can be discriminated by Raman imaging of the mineral content. In conclusion, wide-field Raman imaging is a potentially useful tool for visualization of dental lesions in the clinic. PMID:24781363

  4. Study on the degradation of PLEDs by in-situ micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoxuan; Qin, Zhe; Lin, Haibo; Xu, Wei

    2007-11-01

    Electro luminescence spectra and in-suit micro-Raman spectra was used to study voltaic aging of organic light emitting devices with two kinds of conjugated macromolecule polymer emission layer, one is called PFO-BT15 and the other is poly (2-(4-Ethylhexyl) phenyl-1 , 4-phenylene vinylene) (P-PPV) polymer. The first device has a configuration of ITO glass/ PEDOT( 120nm ) PFO-BT15(80nm)/Ba( 4nm )/Al(200nm) , and we encapsulated the cathode of diode with epoxy resin to reduce the entrance of oxygen and water. After long time current stress, the electro luminescent spectra and Raman spectra show that the polymer device's molecular configuration of polymer layer is unchanged , but the PEDOT anode's breakage which lead to the emission failure of the device, which indicates that this kind of polymer materials have relatively steady photoelectric performance . The second device, during current stress , the reduction of conjugation length is provided by Raman spectroscopy. This reduction of the conjugation length , which dramatically increases the resistance and cuts off the current density , was the main reason for the failure of lighting. These findings provide an important insight into the intrinsic degradation mechanisms of the polymer LEDs and help in the development of even more stable devices.

  5. In situ monitoring of pH titration by Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Elbagerma, M. A.; Azimi, Gholamhassan; Edwards, H. G. M.; Alajtal, A. I.; Scowen, I. J.

    2010-05-01

    Molecular speciation of organic compounds in solution is essential for the understanding of ionic complexation. The Raman technique was chosen because it allows the identification of compounds in different states, and it can give information about the molecular geometry from the analysis of the vibrational spectra. The effect of pH on organic compounds can give information about the ionisation of molecule species. In this study the ionisation steps of salicylic acid and paracetamol have been studied by means of potentiometry coupled with Raman spectroscopy at 30.0 °C in a solution of ionic strength 0.96 mol dm -3 (KNO 3) and 0.04 mol dm -3 (HNO 3). The protonation and deprotonation behaviour of the molecules were studied in different pH regions. The abundance of the three different species in the Raman spectra of aqueous salicylic acid have been identified satisfactorily, characterised, and determined by numeric treatment of the data using a multiwavelength curve-fitting program and confirmed with the observed spectral information.

  6. 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

  7. High-pressure characterization of nitrogen-rich bis-triaminoguanidinium azotetrazolate (TAGzT) by in situ Raman spectroscopy.

    PubMed

    Behler, K D; Ciezak-Jenkins, J A; Sausa, R C

    2013-02-28

    Compounds rich in nitrogen are attracting significant interest not only because of their high energy content but also because they are potentially more environmentally benign in comparison to conventional energetic materials. Given this interest, it is desirable to understand their molecular composition and structural variations with pressure to derive their stability and determine the conditions in which they transform physically or chemically. In this study, we examine the room-temperature isothermal compression behavior of bis-triaminoguanidinium azotetrazolate (TAGzT) by in situ Raman spectroscopy to pressures near 17 GPa. We assign the characteristic vibrational bands and report the effects of pressure on band intensity, line width, and frequency shift. Two prominent peaks near 1370 and 1470 cm(-1) arise from the C-N and N═N symmetric stretches, respectively. Overall, the intensity of these bands and others diminishes with pressure, and their spectral linewidths increase monotonically upon compression. The vibrational frequency modes blue shift linearly upon compression, indicating a generalized stiffening of the bonds as the pressure increases. These results, together with micro Raman spectroscopic analyses of the recovered, decompressed samples, suggest that TAGzT does not undergo any phase transitions within this pressure range. We estimate and report the C-N and N═N intermolecular bond lengths under compression. PMID:23343336

  8. Microscopic observation and in-situ Raman scattering studies on high-pressure phase transformations of Kr hydrate.

    PubMed

    Sasaki, Shigeo; Hori, Shinsuke; Kume, Tetsuji; Shimizu, Hiroyasu

    2006-05-25

    Direct observations through a microscope and in-situ Raman scattering measurements of synthesized single-crystalline Kr hydrate have been performed at pressures up to 5.2 GPa and 296 K. We have observed that the initial cubic structure II (sII) of Kr hydrate successively transforms to a cubic structure I (sI), a hexagonal structure, and an orthorhombic structure (sO) called "filled ice" at 0.45, 0.75, and 1.8 GPa, respectively. The sO phase exists at least up to 5.2 GPa. In addition to these transformations, we have also found the new phase behavior at 1.0 GPa, which is most likely caused by the change of cage occupancy of host water cages by guest Kr atoms without structural change. Raman scattering measurements for observed phases have shown that the lattice vibrational peak at around 130 cm(-1) disappears in the pressure region of sI, which enables us to distinguish the sI phase from sII and sH phases. PMID:16706436

  9. In situ Raman-based measurements of high dissolved methane concentrations in hydrate-rich ocean sediments

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Hester, Keith C.; Ussler, William; Walz, Peter M.; Peltzer, Edward T.; Brewer, Peter G.

    2011-04-01

    Ocean sediment dissolved CH4 concentrations are of interest for possible climate-driven venting from sea floor hydrate decomposition, for supporting the large-scale microbial anaerobic oxidation of CH4 that holds the oceanic CH4 budget in balance, and for environmental issues of the oil and gas industry. Analyses of CH4 from recovered cores near vent locations typically show a maximum of ˜1 mM, close to the 1 atmosphere equilibrium value. We show from novel in situ measurement with a Raman-based probe that geochemically coherent profiles of dissolved CH4 occur rising to 30 mM (pCH4 = 3 MPa) or an excess pressure ˜3× greater than CO2 in a bottle of champagne. Normalization of the CH4 Raman ν1 peak to the ubiquitous water ν2 bending peak provides a fundamental internal calibration. Very large losses of CH4 and fractions of other gases (CO2, H2S) must typically occur from recovered cores at gas rich sites. The new data are consistent with observations of microbial biomass and observed CH4 oxidation rates at hydrate rich sites and support estimates of a greatly expanded near surface oceanic pore water CH4 reservoir.

  10. 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

  11. 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

  12. High-temperature "spectrochronopotentiometry": correlating electrochemical performance with in situ Raman spectroscopy in solid oxide fuel cells.

    PubMed

    Kirtley, John D; Halat, David M; McIntyre, Melissa D; Eigenbrodt, Bryan C; Walker, Robert A

    2012-11-20

    Carbon formation or "coking" on solid oxide fuel cell (SOFC) anodes adversely affects performance by blocking catalytic sites and reducing electrochemical activity. Quantifying these effects, however, often requires correlating changes in SOFC electrochemical efficiency measured during operation with results from ex situ measurements performed after the SOFC has been cooled and disassembled. Experiments presented in this work couple vibrational Raman spectroscopy with chronopotentiometry to observe directly the relationship between graphite deposited on nickel cermet anodes and the electrochemical performance of SOFCs operating at 725 °C. Raman spectra from Ni cermet anodes at open circuit voltage exposed to methane show a strong vibrational band at 1556 cm(-1) assigned to the "G" mode of highly ordered graphite. When polarized in the absence of a gas-phase fuel, these carbon-loaded anodes operate stably, oxidizing graphite to form CO and CO(2). Disappearance of graphite intensity measured in the Raman spectra is accompanied by a steep ∼0.8 V rise in the cell potential needed to keep the SOFC operating under constant current conditions. Continued operation leads to spectroscopically observable Ni oxidation and another steep rise in cell potential. Time-dependent spectroscopic and electrochemical measurements pass through correlated equivalence points providing unequivocal, in situ evidence that identifies how SOFC performance depends on the chemical condition of its anode. Chronopotentiometric data are used to quantify the oxide flux necessary to eliminate the carbon initially present on the SOFC anode, and data show that the oxidation mechanisms responsible for graphite removal correlate directly with the electrochemical condition of the anode as evidenced by voltammetry and impedance measurements. Electrochemically oxidizing the Ni anode damages the SOFC significantly and irreversibly. Anodes that have been reconstituted following electrochemical oxidation of

  13. 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

  14. Sensitive Glycoprotein Sandwich Assays by the Synergistic Effect of In Situ Generation of Raman Probes and Plasmonic Coupling of Ag Core-Au Satellite Nanostructures.

    PubMed

    Bi, Xiaoshuang; Li, Xueyuan; Chen, Dong; Du, Xuezhong

    2016-05-01

    Sensitive surface-enhanced Raman scattering (SERS) assays of glycoproteins have been proposed using p-aminothiophenol (PATP)-embedded Ag core-Au satellite nanostructures modified with p-mercaptophenylboronic acid (PMBA) and the self-assembled monolayer of PMBA on a smooth gold-coated wafer. The apparent Raman probe PATP on the surfaces of the Ag cores underwent a photodimerization to generate 4,4'-dimercaptoazobenzene (DMAB) in situ upon excitation of laser, and the in situ generated DMAB acted as the actual Raman probe with considerably strong SERS signals, which was further enhanced by the plasmonic coupling of the Ag core-Au satellite nanostructures due to the synergistic effect. The sandwich assays of glycoproteins showed high sensitivity and excellent selectivity against nonglycoproteins. The Ag core-Au satellite SERS nanostructures can be used for highly sensitive SERS assays of other analytes. PMID:27064515

  15. In Situ Confocal Raman Microscopy of Hydrated Early Stages of Bacterial Biofilm Formation on Various Surfaces in a Flow Cell.

    PubMed

    Smith-Palmer, Truis; Lin, Sicheng; Oguejiofor, Ikenna; Leng, Tianyang; Pustam, Amanda; Yang, Jin; Graham, Lori L; Wyeth, Russell C; Bishop, Cory D; DeMont, M Edwin; Pink, David

    2016-02-01

    Bacterial biofilms are precursors to biofouling by other microorganisms. Understanding their initiation may allow us to design better ways to inhibit them, and thus to inhibit subsequent biofouling. In this study, the ability of confocal Raman microscopy to follow the initiation of biofouling by a marine bacterium, Pseudoalteromonas sp. NCIMB 2021 (NCIMB 2021), in a flow cell, using optical and confocal Raman microscopy, was investigated. The base of the flow cell comprised a cover glass. The cell was inoculated and the bacteria attached to, and grew on, the cover glass. Bright field images and Raman spectra were collected directly from the hydrated biofilms over several days. Although macroscopically the laser had no effect on the biofilm, within the first 24 h cells migrated away from the position of the laser beam. In the absence of flow, a buildup of extracellular substances occurred at the base of the biofilm. When different coatings were applied to cover glasses before they were assembled into the flow cells, the growth rate, structure, and composition of the resulting biofilm was affected. In particular, the ratio of Resonance Raman peaks from cytochrome c (CC) in the extracellular polymeric substances, to the Raman phenylalanine (Phe) peak from protein in the bacteria, depended on both the nature of the surface and the age of the biofilm. The ratios were highest for 24 h colonies on a hydrophobic surface. Absorption of a surfactant with an ethyleneoxy chain into the hydrophobic coating created a surface similar to that given with a simple PEG coating, where bacteria grew in colonies away from the surface rather than along the surface, and CC:Phe ratios were initially low but increased at least fivefold in the first 48 h. PMID:26903564

  16. Hand-held Raman sensor head for in-situ characterization of meat quality applying a microsystem 671 nm diode laser

    NASA Astrophysics Data System (ADS)

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

    2009-05-01

    A hand-held Raman sensor head was developed for the in-situ characterization of meat quality. As light source, a microsystem based external cavity diode laser module (ECDL) emitting at 671 nm was integrated in the sensor head and attached to a miniaturized optical bench which contains lens optics for excitation and signal collection as well as a Raman filter stage for Rayleigh rejection. The signal is transported with an optical fiber to the detection unit which was in the initial phase a laboratory spectrometer with CCD detector. All elements of the ECDL are aligned on a micro optical bench with 13 x 4 mm2 footprint. The wavelength stability is provided by a reflection Bragg grating and the laser has an optical power of up to 200 mW. However, for the Raman measurements of meat only 35 mW are needed to obtain Raman spectra within 1 - 5 seconds. Short measuring times are essential for the hand-held device. The laser and the sensor head are characterized in terms of stability and performance for in-situ Raman investigations. The function is demonstrated in a series of measurements with raw and packaged pork meat as samples. The suitability of the Raman sensor head for the quality control of meat and other products will be discussed.

  17. In situ imaging of microorganisms in geologic material.

    PubMed

    Tobin, K J; Onstott, T C; DeFlaun, M F; Colwell, F S; Fredrickson, J

    1999-09-01

    In order to fully delineate the interactions of microorganisms with geological substrates, unequivocal identification of intact microbial cells within geologic samples is required without the disruption of either the rock texture or the relationship of the microorganisms to the mineral fabric. To achieve this objective we developed a protocol that enables the visualization of intact microbial cells in petrographic thin sections, avoids detaching the cells from their host mineral surfaces and avoids microbial contamination during the lapidary process. Propidium iodide and POPO-3, nucleic acid stains that specifically target double-stranded DNA and RNA were utilized for in situ visualization of cells in surface and subsurface basalts from northeastern Idaho. Additionally, examination of samples incubated with acetic acid-UL-14C via phosphor imagining facilitated the in situ visualization of 14C labeled biomass. Biomass observed was low (<10(7) cells/g). These observations indicate that the microbial distribution in these rocks exhibits a high degree of spatial heterogeneity at the sub-centimeter scale. PMID:10480264

  18. Hyperspectral coherent anti-Stokes Raman scattering microscopy for in situ analysis of solid-state crystal polymorphs

    NASA Astrophysics Data System (ADS)

    Garbacik, E. T.; Fussell, A. L.; Güres, S.; Korterik, J. P.; Otto, C.; Herek, J. L.; Offerhaus, H. L.

    2013-02-01

    Hyperspectral coherent anti-Stokes Raman scattering (CARS) microscopy is quickly becoming a prominent imaging modality because of its many advantages over the traditional paradigm of multispectral CARS. In particular, recording a significant portion of the vibrational spectrum at each spatial pixel allows image-wide spectral analysis at much higher rates than can be achieved with spontaneous Raman. We recently developed a hyperspectral CARS method, the driving principle behind which is the fast acquisition and display of a hyperspectral datacube as a set of intuitive images wherein each material in a sample appears with a unique trio of colors. Here we use this system to image and analyze two types of polymorphic samples: the pseudopolymorphic hydration of theophylline, and the packing polymorphs of the sugar alcohol mannitol. In addition to these solid-state form modifications we have observed spectral variations of crystalline mannitol and diprophylline as functions of their orientations relative to the optical fields. We use that information to visualize the distributions of these compounds in a pharmaceutical solid oral dosage form.

  19. In situ detection and identification of hair dyes using surface-enhanced Raman spectroscopy (SERS).

    PubMed

    Kurouski, Dmitry; Van Duyne, Richard P

    2015-03-01

    Hair is one of the most common types of physical evidence found at a crime scene. Forensic examination may suggest a connection between a suspect and a crime scene or victim, or it may demonstrate an absence of such associations. Therefore, forensic analysis of hair evidence is invaluable to criminal investigations. Current hair forensic examinations are primarily based on a subjective microscopic comparison of hair found at the crime scene with a sample of suspect's hair. Since this is often inconclusive, the development of alternative and more-accurate hair analysis techniques is critical. In this study, we utilized surface-enhanced Raman spectroscopy (SERS) to demonstrate that artificial dyes can be directly detected on hair. This spectroscopic technique is capable of a confirmatory identification of analytes with single molecule resolution, requires minimal sample, and has the advantage of fluorescence quenching. Our study reveals that SERS can (1) identify whether hair was artificially dyed or not, (2) determine if a permanent or semipermanent colorants were used, and (3) distinguish the commercial brands that are utilized to dye hair. Such analysis is rapid, minimally destructive, and can be performed directly at the crime scene. This study provides a novel perspective of forensic investigations of hair evidence. PMID:25635868

  20. XRD, TEM, IR, Raman and NMR Spectroscopy of In Situ Crystallization of Lithium Disilicate Glass

    NASA Technical Reports Server (NTRS)

    Fuss, T.; Mogus-Milankovic, A.; Ray, C. S.; Lesher, C. E.; Youngman, R.; Day, D. E.

    2006-01-01

    The structure of a Li2O-2SiO2 (LS2) glass was investigated as a function of pressure and temperature up to 6 GPa and 750 C respectively, using XRD, TEM, IR, Raman and NMR spectroscopy. Glass densified at 6 GPa has an average Si-O-Si bond angle approx.7deg lower than that found in glass processed at 4.5 GPa. At 4.5 GPa, lithium disilicate crystallizes from the glass, while at 6 GPa a new high pressure form of lithium metasilicate crystallizes. The new phase, while having lithium metasilicate crystal symmetry, contains at least 4 different Si sites. NMR results for 6 GPa sample indicate the presence of Q4 species with (Q(sup 4))Si-O-Si(Q(sup 4)) bond angles of approx.157deg. This is the first reported occurrence of Q(sup 4) species with such large bond angles in alumina free alkali silicate glass. No five- or six- coordinated Si are found.

  1. In situ Raman study of electrochemical lithium insertion into mesocarbon microbeads heat-treated at various temperatures

    SciTech Connect

    Inaba, Minoru; Yoshida, Hiroyuki; Ogumi, Zempachi

    1996-08-01

    In situ Raman spectra were measured to elucidate the electrochemical lithium insertion mechanism of mesocarbon microbeads (MCMBs) heat-treated at 700 to 2,800 C. The spectral changes of the Raman E{sub 2g2} band of MCMBs heat-treated at 2,800 C showed that the lithium insertion mechanism into the microbeads is similar to that into graphite via the formation of staged graphite intercalation compounds, although a clear phase transition from dilute stage 1 to stage 4 was not observed. For MCMBs heat-treated at 1,800 and 1,000 C the E{sub 2g2} band shifted downward and upward upon charging and discharging, respectively. No discontinuous change suggesting the formation of staged phases was observed, which indicated that lithium is inserted randomly between graphene layers without the formation of staged phases. The charge and discharge profile of MCMBs heat-treated at 700 C showed a large hysteresis. A potential plateau appeared at about 1 V on the discharge curve, which led to a high capacity of 710 mAh/g. In the case of MCMBs heat-treated at 700 C, the peak wave number of the E{sub 2g2} band did not shift at all in the whole potential range during charging and discharging. It was considered that the plateau region of MCMBs heat-treated at 700 C giving the high discharge capacity originates not from lithium species inserted between organized graphene layers, but from lithium doped into regions without organized graphitic structure.

  2. Series of uranyl-4,4'-biphenyldicarboxylates and an occurrence of a cation-cation interaction: hydrothermal synthesis and in situ Raman studies.

    PubMed

    Cantos, Paula M; Jouffret, Laurent J; Wilson, Richard E; Burns, Peter C; Cahill, Christopher L

    2013-08-19

    Three uranium(VI)-bearing materials were synthesized hydrothermally using the organic ligand 4,4'-biphenyldicarboxylic acid: (UO2)(C14O4H8) (1); [(UO2)2(C14O4H8)2(OH)]·(NH4)(H2O) (2); (UO2)2(C14O4H8)(OH)2 (3). Compound 1 was formed after 1 day at 180 °C in an acidic environment (pH(i) = 4.03), and compounds 2 and 3 coformed after 3 days under basic conditions (pH(i) = 7.95). Coformation of all three compounds was observed at higher pH(i) (9.00). Ex situ Raman spectra of single crystals of 1-3 were collected and analyzed for signature peaks. In situ hydrothermal Raman data were also obtained and compared to the ex situ Raman spectra of the title compounds in an effort to acquire formation mechanism details. At pH(i) = 4.00, the formation of 1 was suggested by in situ Raman spectra. At an increased pH(i) (7.90), the in situ data implied the formation of compounds 1 and 3. The most basic conditions (pH(i) = 9.00) yielded a complex mixture of phases consistent with that of increased uranyl hydrolysis. PMID:23909845

  3. Molecular Resolution in situ Imaging of Spontaneous Graphene Exfoliation.

    PubMed

    Elbourne, Aaron; McLean, Ben; Voïtchovsky, Kislon; Warr, Gregory G; Atkin, Rob

    2016-08-18

    All reported methods of graphene exfoliation require external energy input, most commonly from sonication,1 shaking,2 or stirring.3 The reverse process-aggregation of single or few layer graphene sheets-occurs spontaneously in most solvents. This makes producing, and especially storing, graphene in economic quantities challenging,4,5 which is a significant barrier to widespread commercialization. This study reveals ionic liquids (ILs) can spontaneously exfoliate graphene from graphite at room temperature. The process is thermally activated and follows an Arrhenius-type behavior, resulting in thermodynamically stable IL/graphene suspensions. Using atomic force microscopy, the kinetics of the exfoliation could be followed in situ and with subnanometer resolution, showing that both the size and the charge of the constituent IL ions play a key role. Our results provide a general molecular mechanism underpinning spontaneous graphene exfoliation at room temperature in electrically conducting ILs, paving the way for their adoption in graphene-based technology. PMID:27463824

  4. In situ imaging of interfacial precipitation of phosphate on Goethite.

    PubMed

    Wang, Lijun; Putnis, Christine V; Ruiz-Agudo, Encarnación; Hövelmann, Jörn; Putnis, Andrew

    2015-04-01

    Adsorption and subsequent immobilization of orthophosphate on iron oxides is of considerable importance in soil fertility and eutrophication studies. Here, in situ atomic force microscopy (AFM) has been used to probe the interaction of phosphate-bearing solutions with goethite, α-FeOOH, (010) cleavage surfaces. During the dissolution of goethite we observed simultaneous nucleation of nanoparticles (1.0-3.0 nm in height) of iron phosphate (Fe-P) phases at the earliest nucleation stages, subsequent aggregation to form secondary particles (about 6.0 nm in height) and layered precipitates under various pH values and ionic strengths relevant to acid soil solution conditions. The heterogeneous nucleation rates of Fe-P precipitates at phosphate concentrations ranging from 5.0 to 50.0 mM were quantitatively defined. Enhanced goethite dissolution in the presence of high concentration NaCl or AlCl3 leads to a rapid increase in Fe-P nucleation rates, whereas low concentration MgCl2 inhibits goethite dissolution, this in turn influences Fe-P nucleation. Moreover, kinetic data analyses show that low concentrations of citrate caused an increase in the nucleation rate of Fe-P phases. However, at higher concentrations of citrate, nucleation acceleration was reversed with much longer induction times to form Fe-P nuclei. These in situ observations may improve the mechanistic understanding of processes resulting in phosphate immobilization by goethite-rich acid soils in the presence of various inorganic and organic additive molecules. PMID:25763812

  5. In Situ Fabrication of 3D Ag@ZnO Nanostructures for Microfluidic Surface-Enhanced Raman Scattering Systems

    PubMed Central

    2015-01-01

    In this work, we develop an in situ method to grow highly controllable, sensitive, three-dimensional (3D) surface-enhanced Raman scattering (SERS) substrates via an optothermal effect within microfluidic devices. Implementing this approach, we fabricate SERS substrates composed of Ag@ZnO structures at prescribed locations inside microfluidic channels, sites within which current fabrication of SERS structures has been arduous. Conveniently, properties of the 3D Ag@ZnO nanostructures such as length, packing density, and coverage can also be adjusted by tuning laser irradiation parameters. After exploring the fabrication of the 3D nanostructures, we demonstrate a SERS enhancement factor of up to ∼2 × 106 and investigate the optical properties of the 3D Ag@ZnO structures through finite-difference time-domain simulations. To illustrate the potential value of our technique, low concentrations of biomolecules in the liquid state are detected. Moreover, an integrated cell-trapping function of the 3D Ag@ZnO structures records the surface chemical fingerprint of a living cell. Overall, our optothermal-effect-based fabrication technique offers an effective combination of microfluidics with SERS, resolving problems associated with the fabrication of SERS substrates in microfluidic channels. With its advantages in functionality, simplicity, and sensitivity, the microfluidic-SERS platform presented should be valuable in many biological, biochemical, and biomedical applications. PMID:25402207

  6. In Situ Analysis of a Silver Nanoparticle-Precipitating Shewanella Biofilm by Surface Enhanced Confocal Raman Microscopy

    PubMed Central

    Schkolnik, Gal; Schmidt, Matthias; Mazza, Marco G.; Harnisch, Falk; Musat, Niculina

    2015-01-01

    Shewanella oneidensis MR-1 is an electroactive bacterium, capable of reducing extracellular insoluble electron acceptors, making it important for both nutrient cycling in nature and microbial electrochemical technologies, such as microbial fuel cells and microbial electrosynthesis. When allowed to anaerobically colonize an Ag/AgCl solid interface, S. oneidensis has precipitated silver nanoparticles (AgNp), thus providing the means for a surface enhanced confocal Raman microscopy (SECRaM) investigation of its biofilm. The result is the in-situ chemical mapping of the biofilm as it developed over time, where the distribution of cytochromes, reduced and oxidized flavins, polysaccharides and phosphate in the undisturbed biofilm is monitored. Utilizing AgNp bio-produced by the bacteria colonizing the Ag/AgCl interface, we could perform SECRaM while avoiding the use of a patterned or roughened support or the introduction of noble metal salts and reducing agents. This new method will allow a spatially and temporally resolved chemical investigation not only of Shewanella biofilms at an insoluble electron acceptor, but also of other noble metal nanoparticle-precipitating bacteria in laboratory cultures or in complex microbial communities in their natural habitats. PMID:26709923

  7. Multispectral confocal microendoscope for in vivo and in situ imaging

    PubMed Central

    Makhlouf, Houssine; Gmitro, Arthur F.; Tanbakuchi, Anthony A.; Udovich, Josh A.; Rouse, Andrew R.

    2016-01-01

    We describe the design and operation of a multispectral confocal microendoscope. This fiber-based fluorescence imaging system consists of a slit-scan confocal microscope coupled to an imaging catheter that is designed to be minimally invasive and allow for cellular level imaging in vivo. The system can operate in two imaging modes. The grayscale mode of operation provides high resolution real-time in vivo images showing the intensity of fluorescent signal from the specimen. The multispectral mode of operation uses a prism as a dispersive element to collect a full multispectral image of the fluorescence emission. The instrument can switch back and forth nearly instantaneously between the two imaging modes (less than half a second). In the current configuration, the multispectral confocal microendoscope achieves 3-μm lateral resolution and 30-μm axial resolution. The system records light from 500 to 750 nm, and the minimum resolvable wavelength difference varies from 2.9 to 8.3 nm over this spectral range. Grayscale and multispectral imaging results from ex-vivo human tissues and small animal tissues are presented. PMID:19021344

  8. Structural evolution of NM (Ni and Mn) lithium-rich layered material revealed by in-situ electrochemical Raman spectroscopic study

    NASA Astrophysics Data System (ADS)

    Huang, Jing-Xin; Li, Bing; Liu, Bo; Liu, Bi-Ju; Zhao, Jin-Bao; Ren, Bin

    2016-04-01

    Li-rich layered materials are one of promising candidates of cathode materials for energy storage in electric vehicles (EVs) due to their high energy density. The practical application of these materials relies on the in-depth understanding of the crystal structures and reaction mechanisms during the electrochemical processes to overcome the potential decay issue. In this work, in-situ electrochemical Raman spectroscopy has been developed and used to investigate the structural evolution of the Li-rich layered material (0.5LiNi0.5Mn0.5O2·0.5Li2MnO3). An electrochemical Raman spectroscopic cell with an excellent air-tightness and optical signal collection efficiency has been designed and used for in-situ investigation of the NM Li-rich material during the very first two electrochemical cycles. We found that the reactions of Ni2+ to Ni3+ and Ni3+ to Ni4+ appearing in the potential range of from 3.70 V to 4.45 V show a good reversibility. The in-situ Raman spectra after the first two electrochemical cycles also indicate the activation of Li2MnO3 changes the ionic local coordination structure and increases the ionic disorder of the pristine NM Li-rich layered material. This structural change has a great impact on the subsequent electrochemical cycles. The in-situ Raman spectroscopy results can help to improve the performance of NM Li-rich layered materials.

  9. Time-lapse Raman imaging of osteoblast differentiation

    NASA Astrophysics Data System (ADS)

    Hashimoto, Aya; Yamaguchi, Yoshinori; Chiu, Liang-Da; Morimoto, Chiaki; Fujita, Katsumasa; Takedachi, Masahide; Kawata, Satoshi; Murakami, Shinya; Tamiya, Eiichi

    2015-07-01

    Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable.

  10. Time-lapse Raman imaging of osteoblast differentiation

    PubMed Central

    Hashimoto, Aya; Yamaguchi, Yoshinori; Chiu, Liang-da; Morimoto, Chiaki; Fujita, Katsumasa; Takedachi, Masahide; Kawata, Satoshi; Murakami, Shinya; Tamiya, Eiichi

    2015-01-01

    Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable. PMID:26211729

  11. Time-lapse Raman imaging of osteoblast differentiation.

    PubMed

    Hashimoto, Aya; Yamaguchi, Yoshinori; Chiu, Liang-da; Morimoto, Chiaki; Fujita, Katsumasa; Takedachi, Masahide; Kawata, Satoshi; Murakami, Shinya; Tamiya, Eiichi

    2015-01-01

    Osteoblastic mineralization occurs during the early stages of bone formation. During this mineralization, hydroxyapatite (HA), a major component of bone, is synthesized, generating hard tissue. Many of the mechanisms driving biomineralization remain unclear because the traditional biochemical assays used to investigate them are destructive techniques incompatible with viable cells. To determine the temporal changes in mineralization-related biomolecules at mineralization spots, we performed time-lapse Raman imaging of mouse osteoblasts at a subcellular resolution throughout the mineralization process. Raman imaging enabled us to analyze the dynamics of the related biomolecules at mineralization spots throughout the entire process of mineralization. Here, we stimulated KUSA-A1 cells to differentiate into osteoblasts and conducted time-lapse Raman imaging on them every 4 hours for 24 hours, beginning 5 days after the stimulation. The HA and cytochrome c Raman bands were used as markers for osteoblastic mineralization and apoptosis. From the Raman images successfully acquired throughout the mineralization process, we found that β-carotene acts as a biomarker that indicates the initiation of osteoblastic mineralization. A fluctuation of cytochrome c concentration, which indicates cell apoptosis, was also observed during mineralization. We expect time-lapse Raman imaging to help us to further elucidate osteoblastic mineralization mechanisms that have previously been unobservable. PMID:26211729

  12. In situ dissolution analysis of pharmaceutical dosage forms using coherent anti-Stokes Raman scattering (CARS) microscopy

    NASA Astrophysics Data System (ADS)

    Fussell, A. L.; Garbacik, E. T.; Löbmann, K.; Offerhaus, H. L.; Kleinebudde, P.; Strachan, C. J.

    2014-02-01

    A custom-built intrinsic flow-through dissolution setup was developed and incorporated into a home-built CARS microscope consisting of a synchronously pumped optical parametric oscillator (OPO) and an inverted microscope with a 20X/0.5NA objective. CARS dissolution images (512×512 pixels) were collected every 1.12s for the duration of the dissolution experiment. Hyperspectral CARS images were obtained pre- and postdissolution by rapidly imaging while sweeping the wavelength of the OPO in discrete steps so that each frame in the data stack corresponds to a vibrational frequency. An image-processing routine projects this hyperspectral data into a single image wherein each compound appears with a unique color. Dissolution was conducted using theophylline and cimetidine-naproxen co-amorphous mixture. After 15 minutes of theophylline dissolution, hyperspectral imaging showed a conversion of theophylline anhydrate to the monohydrate, confirmed by a peak shift in the CARS spectra. CARS dissolution images showed that monohydrate crystal growth began immediately and reached a maximum with complete surface coverage at about 300s. This result correlated with the UV dissolution data where surface crystal growth on theophylline compacts resulted in a rapidly reducing dissolution rate during the first 300s. Co-amorphous cimetidinenaproxen didn't appear to crystallize during dissolution. We observed solid-state conversions on the compact's surface in situ during dissolution. Hyperspectral CARS imaging allowed visual discrimination between the solid-state forms on the compact's surface. In the case of theophylline we were able to correlate the solid-state change with a change in dissolution rate.

  13. In Situ Focused Beam Reflectance Measurement (FBRM), Attenuated Total Reflectance Fourier Transform Infrared (ATR-FTIR) and Raman Characterization of the Polymorphic Transformation of Carbamazepine

    PubMed Central

    Zhao, Yingying; Bao, Ying; Wang, Jingkang; Rohani, Sohrab

    2012-01-01

    The objective of this work was to study the polymorphic transformation of carbamazepine from Form II to Form III in 1-propanol during seeded isothermal batch crystallization. First, the pure Form II and Form III were obtained and characterized. Then their solubilities and metastable zone limits were measured by in-situ attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and focused beam reflectance measurement (FBRM). A transition temperature at about 34.2 °C was deduced suggesting the enantiotropic nature of this compound over the studied temperature range. To quantify the polymorph ratio during the transformation process, a new in-situ quantitative method was developed to measure the fraction of Form II by Raman spectroscopy. Successful tracking of the nucleation of the stable form and the transformation from Form II to Form III during isothermal crystallization was achieved by Raman spectroscopy and FBRM. The results from these three in-situ techniques, FBRM, FTIR and Raman were consistent with each other. The results showed a strong dependency on the amount of seeds added during isothermal crystallization. PMID:24300186

  14. Surface enhanced Raman spectroscopy hyphenated with surface microextraction for in-situ detection of polycyclic aromatic hydrocarbons on food contact materials.

    PubMed

    Zhang, Min; Zhang, Xiaoli; Shi, Yu-E; Liu, Zhen; Zhan, Jinhua

    2016-09-01

    Highly bioaccumulated polycyclic aromatic hydrocarbons (PAHs) have cause health concerns because of their carcinogenic properties. PAHs could migrate to food from contaminated food contact materials. In this study, a hyphenated technique combining surface enhanced Raman spectroscopy (SERS) with surface microextraction was developed for in-situ on site screening of PAHs on food contact materials. Methanol and 1-propanethiol-modified silver nanoparticles (PTH-Ag NPs) were used to perform the in-situ microextraction and detection of PAHs, respectively. The SERS spectra can be obtained by a portable Raman spectrometer. The vibration of the C-C bond of PTH at 1030cm(-1) was chosen as an internal standard peak. The PTH-Ag NPs showed high uniformity with an RSD of 2.96%. A plot of the normalized SERS intensity against fluoranthene concentration showed a linear relationship (R(2)=0.98). The detection limit could reach 0.27ngcm(-2). The in-situ microextraction-SERS hyphenated technique for the detection of three PAHs at five food contact materials was demonstrated. The method can be also applied to detect PAH mixtures. This in-situ microextraction-SERS hyphenated method demonstrated its ability to rapidly screen PAHs on contaminated food contact materials free from complex sample pretreatment. PMID:27343612

  15. The OCT penlight: in-situ image guidance for microsurgery

    NASA Astrophysics Data System (ADS)

    Galeotti, John; Sajjad, Areej; Wang, Bo; Kagemann, Larry; Shukla, Gaurav; Siegel, Mel; Wu, Bing; Klatzky, Roberta; Wollstein, Gadi; Schuman, Joel S.; Stetten, George

    2010-02-01

    We have developed a new image-based guidance system for microsurgery using optical coherence tomography (OCT), which presents a virtual image in its correct location inside the scanned tissue. Applications include surgery of the cornea, skin, and other surfaces below which shallow targets may advantageously be displayed for the naked eye or low-power magnification by a surgical microscope or loupes (magnifying eyewear). OCT provides real-time highresolution (3 micron) images at video rates within a two or more millimeter axial range in soft tissue, and is therefore suitable for guidance to various shallow targets such as Schlemm's canal in the eye (for treating Glaucoma) or skin tumors. A series of prototypes of the "OCT penlight" have produced virtual images with sufficient resolution and intensity to be useful under magnification, while the geometrical arrangement between the OCT scanner and display optics (including a half-silvered mirror) permits sufficient surgical access. The two prototypes constructed thus far have used, respectively, a miniature organic light emitting diode (OLED) display and a reflective liquid crystal on silicon (LCoS) display. The OLED has the advantage of relative simplicity, satisfactory resolution (15 micron), and color capability, whereas the LCoS can produce an image with much higher intensity and superior resolution (12 micron), although it is monochromatic and more complicated optically. Intensity is a crucial limiting factor, since light flux is greatly diminished with increasing magnification, thus favoring the LCoS as the more practical system.

  16. MicroRaman Spectroscopy and Raman Imaging of Basal Cell Carcinoma

    NASA Astrophysics Data System (ADS)

    Short, M. A.; Zeng, H.; Lui, H.

    2005-03-01

    We have measured the Raman spectra of normal and cancerous skin tissues using a confocal microRaman spectrograph with a sub-micron spatial resolution. We found that the Raman spectrum of a cell nucleolus is different from the spectra measured outside the nucleolus and considerably different from those measured outside the nucleus. In addition, we found significant spectroscopic differences between normal and cancer-bearing sites in the dermis region. In order to utilize these differences for non-invasive skin cancer diagnosis, we have developed a Raman imaging system that clearly demonstrates the structure, location and distribution of cells in unstained skin biopsy samples. Our method is expected to be useful for the detection and characterization of skin cancer based on the known distinct cellular differences between normal and malignant skin.

  17. In situ X-ray Raman spectroscopy study of the hydrogen sorption properties of lithium borohydride nanocomposites.

    PubMed

    Miedema, Piter S; Ngene, Peter; van der Eerden, Ad M J; Sokaras, Dimosthenis; Weng, Tsu-Chien; Nordlund, Dennis; Au, Yuen S; de Groot, Frank M F

    2014-11-01

    Nanoconfined alkali metal borohydrides are promising materials for reversible hydrogen storage applications, but the characterization of hydrogen sorption in these materials is difficult. Here we show that with in situ X-ray Raman spectroscopy (XRS) we can track the relative amounts of intermediates and final products formed during de- and re-hydrogenation of nanoconfined lithium borohydride (LiBH4) and therefore we can possibly identify the de- and re-hydrogenation pathways. In the XRS of nanoconfined LiBH4 at different points in the de- and re-hydrogenation, we identified phases that lead to the conclusion that de- and re-hydrogenation pathways in nanoconfined LiBH4 are different from bulk LiBH4: intercalated lithium (LiCx), boron and lithium hydride were formed during de-hydrogenation, but as well Li2B12H12 was observed indicating that there is possibly some bulk LiBH4 present in the nanoconfined sample LiBH4-C as prepared. Surprisingly, XRS revealed that the de-hydrogenated products of the LiBH4-C nanocomposites can be partially rehydrogenated to about 90% of Li2B12H12 and 2-5% of LiBH4 at a mild condition of 1 bar H2 and 350 °C. This suggests that re-hydrogenation occurs via the formation of Li2B12H12. Our results show that XRS is an elegant technique that can be used for in and ex situ study of the hydrogen sorption properties of nanoconfined and bulk light-weight metal hydrides in energy storage applications. PMID:25231357

  18. New look inside human breast ducts with Raman imaging. Raman candidates as diagnostic markers for breast cancer prognosis: Mammaglobin, palmitic acid and sphingomyelin.

    PubMed

    Abramczyk, Halina; Brozek-Pluska, Beata

    2016-02-25

    Looking inside the human body fascinated mankind for thousands of years. Current diagnostic and therapy methods are often limited by inadequate sensitivity, specificity and spatial resolution. Raman imaging may bring revolution in monitoring of disease and treatment. The main advantage of Raman imaging is that it gives spatial information about various chemical constituents in defined cellular organelles in contrast to conventional methods (liquid chromatography/mass spectrometry, NMR, HPLC) that rely on bulk or fractionated analyses of extracted components. We demonstrated how Raman imaging can drive the progress on breast cancer just unimaginable a few years ago. We looked inside human breast ducts answering fundamental questions about location and distribution of various biochemical components inside the lumen, epithelial cells of the duct and the stroma around the duct during cancer development. We have identified Raman candidates as diagnostic markers for breast cancer prognosis: carotenoids, mammaglobin, palmitic acid and sphingomyelin as key molecular targets in ductal breast cancer in situ, and propose the molecular mechanisms linking oncogenes with lipid programming. PMID:26851089

  19. 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.

  20. 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

  1. 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

  2. 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.

  3. Ultrasonic separation of a suspension for in situ spectroscopic imaging

    NASA Astrophysics Data System (ADS)

    Nogo, Kosuke; Qi, Wei; Mori, Keita; Ogawa, Satoshi; Inohara, Daichi; Hosono, Satsuki; Kawashima, Natsumi; Nishiyama, Akira; Wada, Kenji; Ishimaru, Ichiro

    2016-04-01

    Application of spectroscopic techniques to suspensions is difficult because optical scattering caused by solid particles reduces the accuracy. At the extreme, dense suspensions like blood cannot be analyzed by spectroscopic techniques. In the present study, an ultrasonic standing wave was used to agglomerate fluorescent particles in an aqueous ethanol suspension at the nodes of the standing wave. Relatively clear liquid regions, which contained few particles that could cause optical scattering, appeared around the anti-nodes and were used for spectroscopic imaging. This produced a spectrum that was similar to that of clear aqueous ethanol without any fluorescent particles.

  4. 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.

  5. Raman chemical imaging of the rhizosphere bacterium Pantoea sp. YR343 and its co-culture with Arabidopsis thaliana

    DOE PAGESBeta

    Polisetti, Sneha; Bible, Amber N.; Morrell-Falvey, Jennifer L.; Bohn, Paul W.

    2016-02-29

    Chemical imaging of plant-bacteria co-cultures renders it possible to characterize bacterial populations and behaviors and their interactions with proximal organisms, under conditions closest to the environment in the rhizosphere. Here Raman micro-spectroscopy and confocal Raman imaging are used as minimally invasive probes to study the rhizosphere bacterial isolate, Pantoea sp. YR343, and its co-culture with model plant Arabidopsis thaliana by combining enhanced Raman spectroscopies with electron microscopy and principal component analysis (PCA). The presence of carotenoid pigments in the wild type Pantoea sp. YR343 was characterized using resonance Raman scattering, which was also used to confirm successful disruption of themore » crtB gene in an engineered carotenoid mutant strain. Other components of the Pantoea sp. YR343 cells were imaged in the presence of resonantly enhanced pigments using a combination of surface enhanced Raman imaging and PCA. Pantoea sp. YR343 cells decorated with Ag colloid synthesized ex situ gave spectra dominated by carotenoid scattering, whereas colloids synthesized in situ produced spectral signatures characteristic of flavins in the cell membrane. Scanning electron microscopy (SEM) of whole cells and transmission electron microscopy (TEM) images of thinly sliced cross-sections were used to assess structural integrity of the coated cells and to establish the origin of spectral signatures based on the position of Ag nanoparticles in the cells. Finally, raman imaging was also used to characterize senescent green Arabidopsis thaliana plant roots inoculated with Pantoea sp. YR343, and PCA was used to distinguish spectral contributions from plant and bacterial cells, thereby establishing the potential of Raman imaging to visualize the distribution of rhizobacteria on plant roots.« less

  6. Fluorescence in situ hybridization and spectral imaging of coral-associated bacterial communities.

    PubMed

    Ainsworth, T D; Fine, M; Blackall, L L; Hoegh-Guldberg, O

    2006-04-01

    Microbial communities play important roles in the functioning of coral reef communities. However, extensive autofluorescence of coral tissues and endosymbionts limits the application of standard fluorescence in situ hybridization (FISH) techniques for the identification of the coral-associated bacterial communities. This study overcomes these limitations by combining FISH and spectral imaging. PMID:16598010

  7. Linking heliospheric images of CMEs to their modeled in situ signatures

    NASA Astrophysics Data System (ADS)

    Möstl, Christian; Farrugia, Charles J.; Rollett, Tanja; Temmer, Manuela; Miklenic, Christiane; Veronig, Astrid M.; Galvin, Antoinette B.; Biernat, Helfried K.

    2010-05-01

    We discuss three coronal mass ejection events observed by the STEREO and Wind spacecraft both in situ (STEREO/IMPACT and PLASTIC, and Wind/SWE and MAG instruments) as well as with the Heliospheric Imager instruments (part of the STEREO/SECCHI suite). We are concerned in particular with those CMEs which are seen in the HI images passing over another spacecraft which samples the ICME in situ. These events are of great interest, because they allow a connection between the different data sets, each having its distinct advantages. A pilot study was conducted for the ICME event on June 6 2008 at STEREO-B, which can be tracked all the way to 1 AU in the STEREO-A HI images. The Grad-Shafranov reconstruction technique is used to model the in situ observations to get a larger view of the flux rope in interplanetary space using the assumptions of invariance and time-independence. We show how the orientation of the magnetic flux rope inside the ICME is reflected in the morphology of the CME, and how the CME direction obtained by several methods compares to the in situ model. The same methods are used for two other events whenever applicable. The results are discussed regarding the possibility to forecast ICME properties from HI images.

  8. In situ calibration of an infrared imaging video bolometer in the Large Helical Device.

    PubMed

    Mukai, K; Peterson, B J; Pandya, S N; Sano, R

    2014-11-01

    The InfraRed imaging Video Bolometer (IRVB) is a powerful diagnostic to measure multi-dimensional radiation profiles in plasma fusion devices. In the Large Helical Device (LHD), four IRVBs have been installed with different fields of view to reconstruct three-dimensional profiles using a tomography technique. For the application of the measurement to plasma experiments using deuterium gas in LHD in the near future, the long-term effect of the neutron irradiation on the heat characteristics of an IRVB foil should be taken into account by regular in situ calibration measurements. Therefore, in this study, an in situ calibration system was designed. PMID:25430342

  9. In situ calibration of an infrared imaging video bolometer in the Large Helical Device

    SciTech Connect

    Mukai, K. Peterson, B. J.; Pandya, S. N.; Sano, R.

    2014-11-15

    The InfraRed imaging Video Bolometer (IRVB) is a powerful diagnostic to measure multi-dimensional radiation profiles in plasma fusion devices. In the Large Helical Device (LHD), four IRVBs have been installed with different fields of view to reconstruct three-dimensional profiles using a tomography technique. For the application of the measurement to plasma experiments using deuterium gas in LHD in the near future, the long-term effect of the neutron irradiation on the heat characteristics of an IRVB foil should be taken into account by regular in situ calibration measurements. Therefore, in this study, an in situ calibration system was designed.

  10. 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

  11. Making colourful sense of Raman images of single cells.

    PubMed

    Ashton, Lorna; Hollywood, Katherine A; Goodacre, Royston

    2015-03-21

    In order to understand biological systems it is important to gain pertinent information on the spatial localisation of chemicals within cells. With the relatively recent advent of high-resolution chemical imaging this is being realised and one rapidly developing area of research is the Raman mapping of single cells, an approach whose success has vast potential for numerous areas of biomedical research. However, there is a danger of undermining the potential routine use of Raman mapping due to a lack of consistency and transparency in the way false-shaded Raman images are constructed. In this study we demonstrate, through the use of simulated data and real Raman maps of single human keratinocyte (HaCaT) cells, how changes in the application of colour shading can dramatically alter the final Raman images. In order to avoid ambiguity and potential subjectivity in image interpretation we suggest that data distribution plots are used to aid shading approaches and that extreme care is taken to use the most appropriate false-shading for the biomedical question under investigation. PMID:25666258

  12. In situ Raman spectroscopy of the graphene/water interface of a solution-gated field-effect transistor: electron-phonon coupling and spectroelectrochemistry

    NASA Astrophysics Data System (ADS)

    Binder, J.; Urban, J. M.; Stepniewski, R.; Strupinski, W.; Wysmolek, A.

    2016-01-01

    We present a novel measurement approach which combines the electrical characterization of solution-gated field-effect transistors based on epitaxial bilayer graphene on 4H-SiC (0001) with simultaneous Raman spectroscopy. By changing the gate voltage, we observed Raman signatures related to the resonant electron-phonon coupling. An analysis of these Raman bands enabled the extraction of the geometrical capacitance of the system and an accurate calculation of the Fermi levels for bilayer graphene. An intentional application of higher gate voltages allowed us to trigger electrochemical reactions, which we followed in situ by Raman spectroscopy. The reactions showed a partially reversible character, as indicated by an emergence/disappearance of peaks assigned to C-H and Si-H vibration modes as well as an increase/decrease of the defect-related Raman D band intensity. Our setup provides a highly interesting platform for future spectroelectrochemical research on electrically-induced sorption processes of graphene on the micrometer scale.

  13. Interactions between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    NASA Technical Reports Server (NTRS)

    Liu, Ying D.; Luhmann, Janet G.; Moestl, Christian; Martinez-Oliveros, Juan C.; Bale, Stewart D.; Lin, Robert P.; Harrison, Richard A.; Temmer, Manuela; Webb, David F.; Odstrcil, Dusan

    2013-01-01

    The successive coronal mass ejections (CMEs) from 2010 July 30 - August 1 present us the first opportunity to study CME-CME interactions with unprecedented heliospheric imaging and in situ observations from multiple vantage points. We describe two cases of CME interactions: merging of two CMEs launched close in time and overtaking of a preceding CME by a shock wave. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. Connections between imaging observations and in situ signatures at 1 AU suggest that the merged front is a shock wave, followed by two ejecta observed at Wind which seem to have already merged. In situ measurements show that the CME from July 30 is being overtaken by the shock at 1 AU and is significantly compressed, accelerated and heated. The interaction between the preceding ejecta and shock also results in variations in the shock strength and structure on a global scale, as shown by widely separated in situ measurements from Wind and STEREO B. These results indicate important implications of CME-CME interactions for shock propagation, particle acceleration and space weather forecasting.

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

    NASA Astrophysics Data System (ADS)

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

    2002-10-01

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

  15. Real time Raman imaging to understand dissolution performance of amorphous solid dispersions.

    PubMed

    Tres, Francesco; Treacher, Kevin; Booth, Jonathan; Hughes, Les P; Wren, Stephen A C; Aylott, Jonathan W; Burley, Jonathan C

    2014-08-28

    We have employed for the first time Raman spectroscopic imaging along with multi-variate curve resolution (MCR) analysis to investigate in real time and in-situ the dissolution mechanisms that underpin amorphous solid dispersions, with data being collected directly from the dosage form itself. We have also employed a novel rotating disk dissolution rate (RDDR) methodology to track, through the use of high-performance liquid chromatography (HPLC), the dissolution trends of both drug and polymer simultaneously in multi-component systems. Two formulations of poorly water-soluble felodipine in a polymeric matrix of copovidone VA64 which have different drug loadings of 5% and 50% w/w were used as models with the aim of studying the effects of increasing the amount of active ingredient on the dissolution performance. It was found that felodipine and copovidone in the 5% dispersion dissolve with the same dissolution rate and that no Raman spectral changes accompanied the dissolution, indicating that the two components dissolve as single entity, whose behaviour is dominated by water-soluble copovidone. For the 50% drug-loaded dispersion, partial RDDR values of both felodipine and copovidone were found to be extremely low. MCR Raman maps along with classical Raman/X-ray powder diffraction (XRPD) characterisation revealed that after an initial loss of copovidone from the extrudate the drug re-crystallises, pointing to a release dynamics dependent on the low water solubility and high hydrophobicity of felodipine. Raman imaging revealed different rates of transition from amorphous to crystalline felodipine at different locations within the dosage form. PMID:24910191

  16. 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.

  17. 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.

  18. 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

  19. In Situ Casting and Imaging of the Rat Airway Tree for Accurate 3D Reconstruction

    SciTech Connect

    Jacob, Rick E.; Colby, Sean M.; Kabilan, Senthil; Einstein, Daniel R.; Carson, James P.

    2013-08-01

    The use of anatomically accurate, animal-specific airway geometries is important for understanding and modeling the physiology of the respiratory system. One approach for acquiring detailed airway architecture is to create a bronchial cast of the conducting airways. However, typical casting procedures either do not faithfully preserve the in vivo branching angles, or produce rigid casts that when removed for imaging are fragile and thus easily damaged. We address these problems by creating an in situ bronchial cast of the conducting airways in rats that can be subsequently imaged in situ using 3D micro-CT imaging. We also demonstrate that deformations in airway branch angles resulting from the casting procedure are small, and that these angle deformations can be reversed through an interactive adjustment of the segmented cast geometry. Animal work was approved by the Institutional Animal Care and Use Committee of Pacific Northwest National Laboratory.

  20. Towards eye-safe standoff Raman imaging systems

    NASA Astrophysics Data System (ADS)

    Glimtoft, Martin; Bââth, Petra; Saari, Heikki; Mäkynen, Jussi; Näsilä, Antti; Östmark, Henric

    2014-05-01

    Standoff Raman imaging systems have shown the ability to detect single explosives particles. However, in many cases, the laser intensities needed restrict the applications where they can be safely used. A new generation imaging Raman system has been developed based on a 355 nm UV laser that, in addition to eye safety, allows discrete and invisible measurements. Non-dangerous exposure levels for the eye are several orders of magnitude higher in UVA than in the visible range that previously has been used. The UV Raman system has been built based on an UV Fabry-Perot Interferometer (UV-FPI) developed by VTT. The design allows for precise selection of Raman shifts in combination with high out-of-band blocking. The stable operation of the UV-FPI module under varying environmental conditions is arranged by controlling the temperature of the module and using a closed loop control of the FPI air gap based on capacitive measurement. The system presented consists of a 3rd harmonics Nd:YAG laser with 1.5 W average output at 1000 Hz, a 200 mm Schmidt-Cassegrain telescope, UV-FPI filter and an ICCD camera for signal gating and detection. The design principal leads to a Raman spectrum in each image pixel. The system is designed for field use and easy manoeuvring. Preliminary results show that in measurements of <60 s on 10 m distance, single AN particles of <300 μm diameter can be identified.

  1. Data of low-dose phase-based X-ray imaging for in situ soft tissue engineering assessments

    PubMed Central

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-01-01

    This article presents the data of using three phase-based X-ray imaging techniques to characterize biomaterial scaffold and soft tissues in situ, as reported in our study “Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments” [1]. The examined parameters include the radiation dose, scan time, and image quality, which are all critical to longitudinal in situ live animal assessments. The data presented were obtained from three dimensional imaging of scaffolds in situ cartilage by means of synchrotron-based computed tomography-diffraction enhanced imaging (CT-DEI), analyzer based imaging (CT-ABI), and in-line phase contrast imaging (CT-PCI) at standard and low dose imaging modalities. PMID:26909381

  2. Data of low-dose phase-based X-ray imaging for in situ soft tissue engineering assessments.

    PubMed

    Izadifar, Zohreh; Honaramooz, Ali; Wiebe, Sheldon; Belev, George; Chen, Xiongbiao; Chapman, Dean

    2016-03-01

    This article presents the data of using three phase-based X-ray imaging techniques to characterize biomaterial scaffold and soft tissues in situ, as reported in our study "Low-dose phase-based X-ray imaging techniques for in situ soft tissue engineering assessments" [1]. The examined parameters include the radiation dose, scan time, and image quality, which are all critical to longitudinal in situ live animal assessments. The data presented were obtained from three dimensional imaging of scaffolds in situ cartilage by means of synchrotron-based computed tomography-diffraction enhanced imaging (CT-DEI), analyzer based imaging (CT-ABI), and in-line phase contrast imaging (CT-PCI) at standard and low dose imaging modalities. PMID:26909381

  3. 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.

  4. Raman spectra and optical coherent tomography images of skin

    NASA Astrophysics Data System (ADS)

    Villanueva-Luna, A. E.; Castro-Ramos, J.; Vazquez-Montiel, S.; Flores-Gil, A.; Delgado-Atencio, J. A.; Vazquez-Villa, A.

    2011-03-01

    The optical coherence tomography images are useful to see the internal profile and the structure of material samples. In this work, OCT images were recorded in 10 volunteers with different skin tone which were related to Raman spectra. The areas where we obtained OCT images and Raman spectra were a) index finger nail, b) between index finger and middle finger, c) middle finger tip, d) half of middle finger, e) the thumb finger tip and f) between index finger and thumb, areas measured were for the purpose of finding extracellular fluids with contain triglycerides, cholesterol and glucose that are reported in the literature. The excitation wavelength used for this work was 785 nm, a spectrometer of 6 cm-1 resolution. The spectral region used ranges from 300 to 1800 cm-1. We use an OCT with 930 nm of Central Wavelength, 1.6 mm of Image Depth, 6 mm of image width and 6.2 μm of axial resolution.

  5. Imaging EGFR distribution using surface-enhanced Raman spectroscopy

    NASA Astrophysics Data System (ADS)

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

    2009-02-01

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

  6. Visible and near-infrared imaging spectrometer (VNIS) for in-situ lunar surface measurements

    NASA Astrophysics Data System (ADS)

    He, Zhiping; Xu, Rui; Li, Chunlai; Lv, Gang; Yuan, Liyin; Wang, Binyong; Shu, Rong; Wang, Jianyu

    2015-10-01

    The Visible and Near-Infrared Imaging Spectrometer (VNIS) onboard China's Chang'E 3 lunar rover is capable of simultaneously in situ acquiring full reflectance spectra for objects on the lunar surface and performing calibrations. VNIS uses non-collinear acousto-optic tunable filters and consists of a VIS/NIR imaging spectrometer (0.45-0.95 μm), a shortwave IR spectrometer (0.9-2.4 μm), and a calibration unit with dust-proofing functionality. To been underwent a full program of pre-flight ground tests, calibrations, and environmental simulation tests, VNIS entered into orbit around the Moon on 6 December 2013 and landed on 14 December 2013 following Change'E 3. The first operations of VNIS were conducted on 23 December 2013, and include several explorations and calibrations to obtain several spectral images and spectral reflectance curves of the lunar soil in the Imbrium region. These measurements include the first in situ spectral imaging detections on the lunar surface. This paper describes the VNIS characteristics, lab calibration, in situ measurements and calibration on lunar surface.

  7. Development of an Integrated Raman and Turbidity Fiber Optic Sensor for the In-Situ Analysis of High Level Nuclear Waste - 13532

    SciTech Connect

    Gasbarro, Christina; Bello, Job; Bryan, Samuel; Lines, Amanda; Levitskaia, Tatiana

    2013-07-01

    Stored nuclear waste must be retrieved from storage, treated, separated into low- and high-level waste streams, and finally put into a disposal form that effectively encapsulates the waste and isolates it from the environment for a long period of time. Before waste retrieval can be done, waste composition needs to be characterized so that proper safety precautions can be implemented during the retrieval process. In addition, there is a need for active monitoring of the dynamic chemistry of the waste during storage since the waste composition can become highly corrosive. This work describes the development of a novel, integrated fiber optic Raman and light scattering probe for in situ use in nuclear waste solutions. The dual Raman and turbidity sensor provides simultaneous chemical identification of nuclear waste as well as information concerning the suspended particles in the waste using a common laser excitation source. (authors)

  8. Development of an Integrated Raman and Turbidity Fiber Optic Sensor for the In-Situ Analysis of High Level Nuclear Waste

    SciTech Connect

    Gasbarro, Christina; Bello, Job M.; Bryan, Samuel A.; Lines, Amanda M.; Levitskaia, Tatiana G.

    2013-02-24

    Stored nuclear waste must be retrieved from storage, treated, separated into low- and high-level waste streams, and finally put into a disposal form that effectively encapsulates the waste and isolates it from the environment for a long period of time. Before waste retrieval can be done, waste composition needs to be characterized so that proper safety precautions can be implemented during the retrieval process. In addition, there is a need for active monitoring of the dynamic chemistry of the waste during storage since the waste composition can become highly corrosive. This work describes the development of a novel, integrated fiber optic Raman and light scattering probe for in situ use in nuclear waste solutions. The dual Raman and turbidity sensor provides simultaneous chemical identification of nuclear waste as well as information concerning the suspended particles in the waste using a common laser excitation source.

  9. Enhanced Raman Microprobe Imaging of Single-Wall Carbon Nanotubes

    NASA Technical Reports Server (NTRS)

    Hadjiev, V. G.; Arepalli, S.; Nikolaev, P.; Jandl, S.; Yowell, L.

    2003-01-01

    We explore Raman microprobe capabilities to visualize single wall carbon nanotubes (SWCNTs). Although this technique is limited to a micron scale, we demonstrate that images of individual SWCNTs, bundles or their agglomerates can be generated by mapping Raman active elementary excitations. We measured the Raman response from carbon vibrations in SWCNTs excited by confocal scanning of a focused laser beam. Carbon vibrations reveal key characteristics of SWCNTs as nanotube diameter distribution (radial breathing modes, RBM, 100-300 cm(exp -1)), presence of defects and functional groups (D-mode, 1300-1350 cm(exp -1)), strain and oxidation states of SWCNTs, as well as metallic or semiconducting character of the tubes encoded in the lineshape of the G-modes at 1520-1600 cm(exp - 1). In addition, SWCNTs are highly anisotropic scatterers. The Raman response from a SWCNT is maximal for incident light polarization parallel to the tube axis and vanishing for perpendicular directions. We show that the SWCNT bundle shape or direction can be determined, with some limitations, from a set of Raman images taken at two orthogonal directions of the incident light polarization.

  10. Detecting multiple adulterants in dry milk using Raman chemical imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A Raman chemical imaging method was developed for detecting the presence of multiple chemical adulterants in dry milk powder. Four chemicals (ammonium sulfate, dicyandiamide, melamine, and urea) were added in equal concentrations, between 0.1% and 5.0%, to nonfat dry milk. An area of 25×25 mm2 for e...

  11. Dissociation, transformation, and recombination of Si-H bonds in hydrogenated crystalline silicon determined by in situ micro-Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Ma, Y.; Huang, Y. L.; Job, R.; Fahrner, W. R.

    2005-01-01

    In situ Raman measurements are applied on plasma hydrogenated Czochralski (Cz) silicon samples. The thermal evolutions of several hydrogen related defects, i.e., Si-H bonds (corresponding Raman peak at ˜2095cm-1 ) at the thin surface layer of the sample, Si-H bonds (Raman peaks at ˜2105 and ˜2110cm-1 ) at the inner surfaces of the hydrogen induced platelets (HIPs), and H2 molecules (Raman peak at ˜4150cm-1 ) in the open space of the HIPs are investigated. We find strong evidence for an Si-H bond dissociation and recombination at elevated temperatures (T⩾350°C) and at room temperature (RT), respectively. The dissociation energies of about 2.2 and 2.4eV (assuming a jump frequency of 1013s-1 ) for the Si-H bonds at the thin surface layer and at the inner surfaces of the HIPs are obtained, respectively. It is found that at RT the hydrogen atoms which are released at elevated temperatures are trapped again by the HIPs and passivate the silicon dangling bonds at the inner surfaces of the HIPs or form H2 molecules in the open HIP volume, possibly relating to the basic mechanism of the hydrogen-induced exfoliation of the silicon wafer and the so-called “smart-cut” process.

  12. Laser-induced oxidation kinetics of bismuth surface microdroplets on GaAsBi studied in situ by Raman microprobe analysis.

    PubMed

    Steele, J A; Lewis, R A

    2014-12-29

    We report the cw-laser-induced oxidation of molecular-beam-epitaxy grown GaAsBi bismuth surface microdroplets investigated in situ by micro-Raman spectroscopy under ambient conditions as a function of irradiation power and time. Our results reveal the surface droplets are high-purity crystalline bismuth and the resultant Bi2O3 transformation to be β-phase and stable at room temperature. A detailed Raman study of Bi microdroplet oxidation kinetics yields insights into the laser-induced oxidation process and offers useful real-time diagnostics. The temporal evolution of new β-Bi2O3 Raman modes is shown to be well described by Johnson-Mehl-Avrami-Kolmogorov kinetic transformation theory and while this study limits itself to the laser-induced oxidation of GaAsBi bismuth surface droplets, the results will find application within the wider context of bismuth laser-induced oxidation and direct Raman laser processing. PMID:25607191

  13. Making a Hybrid Microfluidic Platform Compatible for In Situ Imaging by Vacuum-Based Techniques

    SciTech Connect

    Yang, Li; Yu, Xiao-Ying; Zhu, Zihua; Thevuthasan, Suntharampillai; Cowin, James P.

    2011-10-26

    A self-contained microfluidic-based device was designed and fabricated for in situ imaging of aqueous surfaces using vacuum techniques. The device is a hybrid between a microfluidic PDMS block and external accessories, all portable on a small platform (10 cm-8 cm). The key feature is that a small aperture with a diameter of 2-3 micrometers is opened to the vacuum, which serves as a detection window for in situ imaging of aqueous surfaces. Vacuum compatibility and temperature drop due to water vaporization are the two most important challenges in this invention. Theoretical calculations and fabrication strategies are presented from multiple design aspects. In addition, results from the time-of-flight secondary ion mass spectrometry (ToF-SIMS) of aqueous surfaces are presented.

  14. Miniature Variable Pressure Scanning Electron Microscope for In-Situ Imaging and Chemical Analysis

    NASA Technical Reports Server (NTRS)

    Gaskin, Jessica A.; Jerman, Gregory; Gregory, Don; Sampson, Allen R.

    2012-01-01

    NASA Marshall Space Flight Center (MSFC) is leading an effort to develop a Miniaturized Variable Pressure Scanning Electron Microscope (MVP-SEM) for in-situ imaging and chemical analysis of uncoated samples. This instrument development will be geared towards operation on Mars and builds on a previous MSFC design of a mini-SEM for the moon (funded through the NASA Planetary Instrument Definition and Development Program). Because Mars has a dramatically different environment than the moon, modifications to the MSFC lunar mini-SEM are necessary. Mainly, the higher atmospheric pressure calls for the use of an electron gun that can operate at High Vacuum, rather than Ultra-High Vacuum. The presence of a CO2-rich atmosphere also allows for the incorporation of a variable pressure system that enables the in-situ analysis of nonconductive geological specimens. Preliminary testing of Mars meteorites in a commercial Environmental SEM(Tradmark) (FEI) confirms the usefulness of lowcurrent/low-accelerating voltage imaging and highlights the advantages of using the Mars atmosphere for environmental imaging. The unique capabilities of the MVP-SEM make it an ideal tool for pursuing key scientific goals of NASA's Flagship Mission Max-C; to perform in-situ science and collect and cache samples in preparation for sample return from Mars.

  15. Interaction between Coronal Mass Ejections Viewed in Coordinated Imaging and In Situ Observations

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Luhmann, J. G.; Moestl, C.; Martinez Oliveros, J. C.; Harrison, R.; Temmer, M.; Bale, S.; Lin, R. P.

    2011-12-01

    Interaction between coronal mass ejections (CMEs), which is expected to be a frequent phenomenon, has important implications for both space weather and basic plasma physics. First, the interaction alters the global heliospheric configuration, which may lead to favorable conditions for geomagnetic storm generation. Second, the interaction implies significant energy and momentum transfer between the interacting CMEs where magnetic reconnection may take place. Third, in case a shock is driven by the trailing CME, interesting physical processes may occur when the shock is propagating through the preceding one, such as modifications in the shock strength, particle intensity and transport. There are successive CMEs on July 30 - August 1, 2011, which presents us the first opportunity to study CME-CME interaction with unprecedented heliospheric imaging and in situ observations from a fleet of spacecraft. The first two CMEs on August 1 interact close to the Sun and form a merged front, which then overtakes the July 30 CME near 1 AU, as revealed by wide-angle imaging observations. In situ measurements indicate that the first two CMEs on August 1 seem to have already merged at 0.7 and 1 AU, and at 1 AU their shock is propagating into the CME from July 30. We will report and discuss the CME-CME interaction signatures from the coordinated imaging and in situ observations in this presentation.

  16. 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

  17. 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.

  18. Analysis of In-Situ Organic and Mineral Compounds Relevant to Martian Astrobiology Using 266 nm Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Eshelman, E.; Daly, M. G.; Slater, G.; Dietrich, P.; Gravel, J. F.; Cloutis, E.

    2014-12-01

    Raman spectroscopy has become increasingly desirable for astrobiological investigations on Mars due to the potential for stand-off measurements, sensitivity to organic and mineral targets, and detection on unprepared surfaces. While the majority of existing Raman instruments intended for planetary exploration operate in the visible or near infrared, an ultraviolet Raman wavelength offers potential advantages including increased Raman cross section, decreased fluorescence in the Raman window, and increased signal due to resonance with some organics. This work presents a Raman spectrometer with an excitation of 266 nm, designed around the putative requirements of a flight instrument. We demonstrate spatial mapping of organic and mineral compounds on Mars analogue samples from the Canadian Arctic and the Atacama Desert, showcasing the reduced fluorescence and increased scattering efficiency compared to longer wavelengths. The Raman window provided by a 266 nm excitation is advantageously positioned to observe fluorescence bands that are characteristic to terrestrial bacteria yet do not overlap with the Raman signal. We present the potential for time-resolved nanosecond scale gating of the detector in characterizing mineral and organic fluorescence by measuring the fluorescence lifetime of endoliths in gypsum. The characteristic short lifetime of the bacterial fluorescence provides additional information regarding the presence of organic carbon in the sample, and therefore combined Raman-fluorescence measurements may increase the sensitivity of the instrument to organic carbon. This research was carried out at the Planetary Instrumentation Laboratory at York University, and supported in part by both the Canadian Space Agency (CSA) and by the Natural Sciences and Engineering Research Council of Canada (NSERC).

  19. Stream temperature estimated in situ from thermal-infrared images: best estimate and uncertainty

    NASA Astrophysics Data System (ADS)

    Iezzi, F.; Todisco, M. T.

    2015-11-01

    The paper aims to show a technique to estimate in situ the stream temperature from thermal-infrared images deepening its best estimate and uncertainty. Stream temperature is an important indicator of water quality and nowadays its assessment is important particularly for thermal pollution monitoring in water bodies. Stream temperature changes are especially due to the anthropogenic heat input from urban wastewater and from water used as a coolant by power plants and industrial manufacturers. The stream temperatures assessment using ordinary techniques (e.g. appropriate thermometers) is limited by sparse sampling in space due to a spatial discretization necessarily punctual. Latest and most advanced techniques assess the stream temperature using thermal-infrared remote sensing based on thermal imagers placed usually on aircrafts or using satellite images. These techniques assess only the surface water temperature and they are suitable to detect the temperature of vast water bodies but do not allow a detailed and precise surface water temperature assessment in limited areas of the water body. The technique shown in this research is based on the assessment of thermal-infrared images obtained in situ via portable thermal imager. As in all thermographic techniques, also in this technique, it is possible to estimate only the surface water temperature. A stream with the presence of a discharge of urban wastewater is proposed as case study to validate the technique and to show its application limits. Since the technique analyzes limited areas in extension of the water body, it allows a detailed and precise assessment of the water temperature. In general, the punctual and average stream temperatures are respectively uncorrected and corrected. An appropriate statistical method that minimizes the errors in the average stream temperature is proposed. The correct measurement of this temperature through the assessment of thermal- infrared images obtained in situ via portable

  20. Detecting multiple adulterants in dry milk using Raman chemical imaging

    NASA Astrophysics Data System (ADS)

    Qin, Jianwei; Chao, Kuanglin; Kim, Moon S.

    2012-05-01

    This study investigated the potential of Raman chemical imaging for simultaneously detecting multiple adulterants in milk powder. Potential chemical adulterants, including ammonium sulfate, dicyandiamide, melamine, and urea, were together mixed into nonfat dry milk in the concentration range of 0.1%-5.0% for each adulterant. A benchtop point-scan Raman imaging system using a 785-nm laser was assembled to acquire hyperspectral images in the wavenumber range of 102-2538 cm-1. Each mixture was imaged in an area of 25×25 mm2 with a spatial resolution of 0.25 mm. Selfmodeling mixture analysis (SMA) was used to extract pure component spectra, by which the four types of the adulterants were identified at all concentration levels based on their spectral information divergence values to the reference spectra. Raman chemical images were created using the contribution images from SMA, and their use to effectively visualize identification and spatial distribution of the multiple adulterant particles in the dry milk was demonstrated.

  1. Raman Microscopy : A Versatile Approach to Bio-Imaging

    NASA Astrophysics Data System (ADS)

    McGarvey, J. J.; Renwick Beattie, J.

    Raman microscopy has become established as a key probe technique in biology and biomedicine. In combination with imaging and mapping it has been employed in the investigation of a diverse array of problems ranging from ex vivo and in vivo single cell studies to elucidation of the often complex, interacting structures which constitute human and animal tissues. This chapter emphasises the unique attributes of Raman microscopy as a bioimaging technique, including its non-invasive, spectral multiplexing ability, allied with high spatial resolution and underpinned by a range of multivariate data processing methods. A number of illustrative examples have been selected for discussion from the fields of molecular biology, ophthalmology, respiratory medicine as well as some non-medical examples. Recent advances and pointers to future activity in the uses of Raman microscopy as a structurally and functionally informative bioimaging technique are briefly considered.

  2. Raman characterization of high temperature materials using an imaging detector

    SciTech Connect

    Rosenblatt, G.M.; Veirs, D.K.

    1989-03-01

    The characterization of materials by Raman spectroscopy has been advanced by recent technological developments in light detectors. Imaging photomultiplier-tube detectors are now available that impart position information in two dimensions while retaining photon-counting sensitivity, effectively greatly reducing noise. The combination of sensitivity and reduced noise allows smaller amounts of material to be analyzed. The ability to observe small amount of material when coupled with position information makes possible Raman characterization in which many spatial elements are analyzed simultaneously. Raman spectroscopy making use of these capabilities has been used, for instance, to analyze the phases present in carbon films and fibers and to map phase-transformed zones accompanying crack propagation in toughened zirconia ceramics. 16 refs., 6 figs., 2 tabs.

  3. Continuous in situ fluorescence imaging of an ultracold Fermi gas in an optical lattice

    NASA Astrophysics Data System (ADS)

    Anderson, Rhys; Edge, Graham; Day, Ryan; Nino, Daniel; Trotzky, Stefan; Thywissen, Joseph

    2015-05-01

    We demonstrate continuous in situ fluorescence imaging of ultracold fermionic 40K atoms held in a three-dimensional optical lattice with 527 nm periodicity. Using a 4S-4P1/2 grey molasses cooling scheme with a coherent dark state, we obtain a photon scattering rate exceeding 1 kHz while measuring a steady-state population of the vibrational ground state of 80%. Collecting the scattered photons through a 200 μm thin sapphire vacuum window and into a microscope objective allows us to image the in situ density distribution of the lattice gas. Spatially selective state manipulation is used to reduce the number of occupied lattice planes along the imaging direction, as well as to create density patterns along the transverse direction. We characterize the performance of the imaging protocol over a wide range of parameters. For larger-than-unity site occupation we observe efficient removal of atoms due to light-assisted collisions. Singly occupied lattice sites can be continuously imaged for several seconds. This method is suitable for high-resolution imaging of a many-body system in the Fermi-Hubbard regime.

  4. Length-Scale-Dependent Phase Transformation of LiFePO4 : An In situ and Operando Study Using Micro-Raman Spectroscopy and XRD.

    PubMed

    Siddique, N A; Salehi, Amir; Wei, Zi; Liu, Dong; Sajjad, Syed D; Liu, Fuqiang

    2015-08-01

    The charge and discharge of lithium ion batteries are often accompanied by electrochemically driven phase-transformation processes. In this work, two in situ and operando methods, that is, micro-Raman spectroscopy and X-ray diffraction (XRD), have been combined to study the phase-transformation process in LiFePO4 at two distinct length scales, namely, particle-level scale (∼1 μm) and macroscopic scale (∼several cm). In situ Raman studies revealed a discrete mode of phase transformation at the particle level. Besides, the preferred electrochemical transport network, particularly the carbon content, was found to govern the sequence of phase transformation among particles. In contrast, at the macroscopic level, studies conducted at four different discharge rates showed a continuous but delayed phase transformation. These findings uncovered the intricate phase transformation in LiFePO4 and potentially offer valuable insights into optimizing the length-scale-dependent properties of battery materials. PMID:26073651

  5. Gold Nano-Popcorn Based Targeted Diagonosis, Nanotherapy Treatment and In-Situ Monitoring of Photothermal Therapy Response of Prostate Cancer Cells Using Surface Enhanced Raman Spectroscopy

    PubMed Central

    Lu, Wentong; Singh, Anant Kumar; Khan, Sadia Afrin; Senapati, Dulal; Yu, Hongtao; Ray, Paresh Chandra

    2010-01-01

    Prostate cancer is the second leading cause of cancer-related death among the American male population and the cost of treating prostate cancer patients is about $10 billion/year in the US. Current treatments are mostly ineffective against advanced stage prostate cancer disease and are often associated with severe side effects. Driven by the need, in this manuscript, we report multifunctional nanotechnology-driven gold nano-popcorn based surface enhanced Raman scattering (SERS) assay for targeted sensing, nanotherapy treatment and in-situ monitoring of photothermal nanotherapy response during the therapy process. Our experimental data show that in the presence of LNCaP human prostate cancer cell, multifunctional popcorn shape gold nanoparticle forms several hot spots and provides a significant enhancement of the Raman signal intensity by several orders of magnitude (2.5 × 109). As a result, it can recognize human prostate cancer cell in 50 cells level. Our results indicate that the localized heating that occurs during NIR irradiation is able to cause irreparable cellular damage of the prostate cancer cell. Our in-situ time dependent results demonstrates for the first time that by monitoring SERS intensity change, one can monitor photo thermal nanotherapy response during therapy process. Possible mechanisms and operating principle of our SERS assay have been discussed. Ultimately, this nanotechnology driven assay could have enormous potential applications in rapid, on-site targeted sensing, nanotherapy treatment and monitoring of nanotherapy process which is critical to providing effective treatment of cancer disease. PMID:21128627

  6. Toward Surface-Enhanced Raman Imaging of Latent Fingerprints

    SciTech Connect

    Connatser, Raynella M; Prokes, Sharka M.; Glembocki, Orest; Schuler, Rebecca A.; Gardner, Charles W.; Lewis Sr, Samuel Arthur; Lewis, Linda A

    2010-01-01

    Exposure to light or heat, or simply a dearth of fingerprint material, renders some latent fingerprints undetectable using conventional methods. We begin to address such elusive fingerprints using detection targeting photo- and thermally stable fingerprint constituents: surface-enhanced Raman spectroscopy (SERS). SERS can give descriptive vibrational spectra of amino acids, among other robust fingerprint constituents, and good sensitivity can be attained by improving metal-dielectric nanoparticle substrates. With SERS chemical imaging, vibrational bands intensities recreate a visual of fingerprint topography. The impact of nanoparticle synthesis route, dispersal methodology-deposition solvent, and laser wavelength are discussed, as are data from enhanced vibrational spectra of fingerprint components. SERS and Raman chemical images of fingerprints and realistic contaminants are shown. To our knowledge, this represents the first SERS imaging of fingerprints. In conclusion, this work progresses toward the ultimate goal of vibrationally detecting latent prints that would otherwise remain undetected using traditional development methods.

  7. In situ 24 kHz coherent imaging of morphology change in laser percussion drilling.

    PubMed

    Webster, Paul J L; Yu, Joe X Z; Leung, Ben Y C; Anderson, Mitchell D; Yang, Victor X D; Fraser, James M

    2010-03-01

    We observe sample morphology changes in real time (24 kHz) during and between percussion drilling pulses by integrating a low-coherence microscope into a laser micromachining platform. Nonuniform cut speed and sidewall evolution in stainless steel are observed to strongly depend on assist gas. Interpulse morphology relaxation such as hole refill is directly imaged, showing dramatic differences in the material removal process dependent on pulse duration/peak power (micros/0.1 kW, ps/20 MW) and material (steel, lead zirconate titanate PZT). Blind hole depth precision is improved by over 1 order of magnitude using in situ feedback from the imaging system. PMID:20195306

  8. In situ imaging of lung alveoli with an optical coherence tomography needle probe

    NASA Astrophysics Data System (ADS)

    Quirk, Bryden C.; McLaughlin, Robert A.; Curatolo, Andrea; Kirk, Rodney W.; Noble, Peter B.; Sampson, David D.

    2011-03-01

    In situ imaging of alveoli and the smaller airways with optical coherence tomography (OCT) has significant potential in the assessment of lung disease. We present a minimally invasive imaging technique utilizing an OCT needle probe. The side-facing needle probe comprises miniaturized focusing optics consisting of no-core and GRIN fiber encased within a 23-gauge needle. 3D-OCT volumetric data sets were acquired by rotating and retracting the probe during imaging. The probe was used to image an intact, fresh (not fixed) sheep lung filled with normal saline, and the results validated against a histological gold standard. We present the first published images of alveoli acquired with an OCT needle probe and demonstrate the potential of this technique to visualize other anatomical features such as bifurcations of the bronchioles.

  9. In situ Determination of Pore-water pH in Reducing Sediments near Methane Seeps and Vents by Laser Raman Spectroscopy

    NASA Astrophysics Data System (ADS)

    Peltzer, E. T.; Walz, P. M.; Luna, M.; Zhang, X.; Brewer, P. G.

    2015-12-01

    Sediments near methane vents and seeps are often anoxic in nature due to the microbial oxidation of organic matter. When the pore-water oxygen is consumed, the microbial population resorts to using sulfate as the terminal electron receptor. For the anaerobic oxidation of methane, the net reaction is: CH4 + SO42- = HCO3- + HS- + H2O. Hydrogen sulfide produced by this reaction dissociates into bisulfide in proportion to the pore-water pH. Since the first pK of H2S is about 7 and close to the in situ pore-water pH, it satisfies the criteria for a useful pH indicating dye. Although the two forms of hydrogen sulfide are not visually discernable by the human eye, these two forms have distinct Raman spectra and thus can be easily quantified using an in situ spectrometer. The relative Raman cross-sections of the hydrogen sulfide species were determined in the laboratory across a range of relevant pH values and at the approximate salinity (ionic strength) and temperature of deep-sea pore waters. With this calibration, it is simple to compute the pore-water pH from the relative abundance of the two sulfide species: pH = pK1 + log10([HS-]/[H2S]). Pore-water profiles were investigated at several sites in the Santa Monica basin around methane mounds, gas vents and cold seeps. A titanium pore-water probe with a stainless steel frit was used to filter and collect pore-water samples at 5-10 cm intervals in the top 50-60 cm of sediment. Filtration and collection of the pore-water samples was usually accomplished in 5-10 minutes, with acquisition of the laser Raman spectra requiring only 2-4 minutes additional time. Vertical profiles of sulfate, total sulfide (H2S + HS-), methane and pH were collected simultaneously using the laser Raman spectrometer and pore-water profile sampler. Sulfate was observed to decrease from seawater concentrations to below detection limits while both methane and total sulfide increased proportionally to the sulfate loss. Once total sulfide concentrations

  10. In situ identification and analysis of automotive paint pigments using line segment excitation Raman spectroscopy: I. Inorganic topcoat pigments.

    PubMed

    Suzuki, E M; Carrabba, M

    2001-09-01

    Several applications of Raman spectroscopy in the forensic sciences have recently been demonstrated, but few have involved the analysis of paints. Undoubtedly, this is a reflection of the sample degradation problems often encountered when a visible or near-infrared laser is focused on a light-absorbing matrix. In this study, a dispersive CCD Raman spectrometer (785 nm) was used in a configuration which collected scattered light from an excitation region 3 mm long and 80 microm wide, instead of from a focused spot. Sample degradation was not observed, and Raman spectra of automotive paints of all colors were readily obtained. Most of the paints analyzed were U.S. automobile original finishes (1974 to 1989) from the Reference Collection of Automotive Paints, and the inorganic pigments examined were those which had been identified previously by infrared spectroscopy in finishes from this collection. Prominent peaks of rutile were observed in Raman spectra of light-colored nonmetallic finishes for both monocoats and basecoat/clearcoat systems, and the rutile peaks are readily distinguished from those of anatase. The lead chromates (Chrome Yellow, Molybdate Orange, and silica-encapsulated versions of the two) are the strongest Raman scatterers among the pigments examined, and Chrome Yellow was identified by Raman spectroscopy in several yellow and orange nonmetallic monocoats for which infrared absorptions of this pigment were not observed. Raman spectroscopy also provides an unequivocal means to distinguish Chrome Yellow from Molybdate Orange. This is particularly helpful for the analysis of paints containing light pigment loads or encapsulated pigments since the two formulations cannot be differentiated by infrared spectroscopy in such cases. The iron-containing pigments, ferric oxide, hydrous ferric oxide, and Prussian Blue, are relatively weak Raman scatterers, but peaks of hydrous ferric oxide and Prussian Blue were observed in spectra of paints containing heavy