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Sample records for ir transmission diffraction

  1. Efficient IR Transmission Diffraction Grating for Circularly Polarized Light

    NASA Technical Reports Server (NTRS)

    Cole, Helen; Chambers, Diana

    1999-01-01

    Numerical methods, using rigorous coupled wave theory, are used to design rectangular relief diffraction gratings for an infrared application which requires comparable first order efficiencies in the TE and TM polarization states. The depth, period, and fill factor of the grating are varied to identify optimal two level binary lamellar grating profiles which predict efficiencies for individual TM and TE polarizations above 75 percent, while keeping the difference between the two efficiencies within 10 percent. The application at hand is a rotating, transmissive diffractive scanner for space-based coherent lidar. The operating wavelength is 2.0 microns. A collimated, circularly polarized beam is incident on the diffractive scanner at the Bragg angle; 30 and 45 degree beam deflection angles being studied. Fused silica is the substrate material of choice. Selected designs are fabricated on 3 inch fused silica substrates using lithographic methods. The performance of the test pieces is measured and compared to theoretical predictions.

  2. Electron Diffraction Using Transmission Electron Microscopy

    PubMed Central

    Bendersky, Leonid A.; Gayle, Frank W.

    2001-01-01

    Electron diffraction via the transmission electron microscope is a powerful method for characterizing the structure of materials, including perfect crystals and defect structures. The advantages of electron diffraction over other methods, e.g., x-ray or neutron, arise from the extremely short wavelength (≈2 pm), the strong atomic scattering, and the ability to examine tiny volumes of matter (≈10 nm3). The NIST Materials Science and Engineering Laboratory has a history of discovery and characterization of new structures through electron diffraction, alone or in combination with other diffraction methods. This paper provides a survey of some of this work enabled through electron microscopy.

  3. Transmissive Diffractive Optical Element Solar Concentrators

    NASA Technical Reports Server (NTRS)

    Baron, Richard; Moynihan, Philip; Price, Douglas

    2008-01-01

    Solar-thermal-radiation concentrators in the form of transmissive diffractive optical elements (DOEs) have been proposed as alternatives to mirror-type solar concentrators now in use. In comparison with functionally equivalent mirror-type solar concentrators, the transmissive, diffractive solar concentrators would weigh and cost less, and would be subject to relaxed mechanical tolerances. A DOE concentrator would be made from a thin, flat disk or membrane of a transmissive material having a suitable index of refraction. By virtue of its thinness, the DOE concentrator would have an areal mass density significantly less than that of a functionally equivalent conventional mirror. The DOE concentrator would have a relatively wide aperture--characterized by a focal-length/aperture-diameter ratio ('f number') on the order of 1. A kinoform (a surface-relief phase hologram) of high diffractive order would be microfabricated onto one face of the disk. The kinoform (see figure) would be designed to both diffract and refract incident solar radiation onto a desired focal region, without concern for forming an image of the Sun. The high diffractive order of this kinoform (in contradistinction to the low diffractive orders of some other kinoforms) would be necessary to obtain the desired f number of 1, which, in turn, would be necessary for obtaining a desired concentration ratio of 2,500 or greater. The design process of optimizing the concentration ratio of a proposed DOE solar concentrator includes computing convolutions of the optical bandwidth of the Sun with the optical transmission of the diffractive medium. Because, as in the cases of other non-imaging, light-concentrating optics, image quality is not a design requirement, the process also includes trading image quality against concentration ratio. A baseline design for one example calls for an aperture diameter of 1 m. This baseline design would be scalable to a diameter as large as 10 m, or to a smaller diameter for a

  4. Diffractive wave transmission in dispersive media

    NASA Astrophysics Data System (ADS)

    Lescarret, Vincent

    The aim of this paper is to study the reflection-transmission of diffractive geometrical optic rays described by semi-linear symmetric hyperbolic systems such as the Maxwell-Lorentz equations with the anharmonic model of polarization. The framework is that of P. Donnat's thesis [P. Donnat, Quelques contributions mathématiques en optique non linéaire, chapters 1 and 2, thèse, 1996] and V. Lescarret [V. Lescarret, Wave transmission in dispersive media, M3AS 17 (4) (2007) 485-535]: we consider an infinite WKB expansion of the wave over long times/distances O(1/ɛ) and because of the boundary, we decompose each profile into a hyperbolic (purely oscillating) part and elliptic (evanescent) part as in M. William [M. William, Boundary layers and glancing blow-up in nonlinear geometric optics, Ann. Sci. École Norm. Sup. 33 (2000) 132-209]. Then to get the usual sublinear growth on the hyperbolic part of the profiles, for every corrector, we consider E, the space of bounded functions decomposing into a sum of pure transports and a "quasi compactly" supported part. We make a detailed analysis on the nonlinear interactions on E which leads us to make a restriction on the set of resonant phases. We finally give a convergence result which justifies the use of "quasi compactly" supported profiles.

  5. Near diffraction limited mid-IR spectromicroscopy using frequency upconversion

    NASA Astrophysics Data System (ADS)

    Sanders, Nicolai; Dam, Jeppe Seidelin; Tidemand-Lichtenberg, Peter; Pedersen, Christian

    2014-02-01

    Mid-infrared microscopy and spectroscopy is interesting due to its medical, biological and chemical applications. Spectromicroscopy can be used for histopathology, sample analysis and diagnosis. The ability to do spectromicroscopy in the 2.5 to 4.5 μm wavelength range where many organic molecules have their fundamental vibrations, with the addition of sufficient spectroscopic resolution to resolve these bands, can e.g. potentially allow for diagnostics without the need for staining of the sample. On a longer timeframe, mid-IR spectromicroscopy has the potential for in-vivo diagnostics, combining morphological and spectral imaging. Recent developments in nonlinear frequency upconversion, have demonstrated the potential to perform both imaging and spectroscopy in the mid-IR range at unparalleled low levels of illumination, the low upconversion detector noise being orders of magnitude below competing technologies. With these applications in mind, we have incorporated microscopy optics into an image upconversion system, achieving near diffraction limited spatial resolution in the 3 μm range. Spectroscopic information is further acquired by appropriate control of the phase match condition of the upconversion process. Multispectral images for a region of interest can be obtained by XY-scanning this region of interest within the field of view of the mid-IR upconversion system. Thus, the whole region of interest can be imaged with all available converter wavelengths, and the spectral representation becomes equal for all points in the image. In addition, the range of converted/imaged wavelengths can be tuned continuously by changing the temperature of the crystal, or discretely by using a different poling channel in the PPLN crystal.

  6. Diffraction modelling of laser ablation using transmission masks

    NASA Astrophysics Data System (ADS)

    Dyer, P. E.; Mackay, J.; Walton, C. D.

    2004-10-01

    We present an analysis of near-field diffraction effects in ablation with transmission masks, based on coupling a simplified form of the Fresnel-Kirchhoff diffraction integral with basic models for material removal. Modelling for square, hexagonal and circular proximity masks is described and compared with previously reported experiments on glass, silicon and polyimide using excimer, femtosecond and CO2 lasers. The model has general applicability and can provide useful insight into the effect of near-field diffraction in ablation patterning.

  7. Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

    SciTech Connect

    Zieliński, W. Płociński, T.; Kurzydłowski, K.J.

    2015-06-15

    We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens prepared by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.

  8. Highlighting material structure with transmission electron diffraction correlation coefficient maps.

    PubMed

    Kiss, Ákos K; Rauch, Edgar F; Lábár, János L

    2016-04-01

    Correlation coefficient maps are constructed by computing the differences between neighboring diffraction patterns collected in a transmission electron microscope in scanning mode. The maps are shown to highlight material structural features like grain boundaries, second phase particles or dislocations. The inclination of the inner crystal interfaces are directly deduced from the resulting contrast. PMID:26866276

  9. Diffraction grating transmission efficiencies for XUV and soft x rays.

    PubMed

    Schnopper, H W; Van Speybroeck, L P; Delvaille, J P; Epstein, A; Källne, E; Bachrach, R Z; Dijkstra, J; Lantward, L

    1977-04-01

    Efficiencies for diffraction of 45-275-eV x rays into orders by interferometrically formed, electrodeposited, gold transmission gratings have been measured on the 4 degrees beam line at the Stanford Synchrotron Radiation Project (SSRP). Anomalous dispersion affects the observed efficiency since the gold is partially transmitting to x rays. Model calculations which include anomalous dispersion are in good agreement with observations. With a suitable choice of material and thickness, a grating can be optimized for a given wavelength range by reducing the zero order transmission and enhancing the higher orders. Even orders are suppressed for a grating with equal slit and wire sizes. PMID:20168641

  10. Flexible waveguides for transmission of IR radiation and surgical applications

    NASA Astrophysics Data System (ADS)

    Croitoru, Nathan I.; Gannot, Israel; Dror, Jacob; Imber, A.; Kaplan, Isaac; Calderon, Shlomo

    1993-05-01

    Infrared (IR) radiation emitted by lasers is a very important tool in surgery applications. This type of laser energy is used for cutting and soldering of tissues, cauterization, evaporation of growths, opening blocked passages and others. The most important lasers which give radiation in the mid-IR region are the CO2 laser ((lambda) equals 10.6 micrometers ), CO laser ((lambda) equals 5 mm) and the Er-YAG laser ((lambda) equals 2.94 micrometers ). In our laboratory a plastic, flexible, hollow waveguide suitable for mid-IR energy transmission was devised. This waveguide is used successfully in surgery. The waveguide is made of a plastic tube covered internally with a thin metal layer (Ag) and a dielectric overlayer (AgI). A theoretical ray model was also developed which has described quantitatively the propagation of radiation through the waveguide under straight and bent trajectories. The thickness and index of refraction of the dielectric layer is the essential parameter which determines the attenuation of transmitted energy through the waveguide. Powers up to 50 watts of CO2 laser can be transmitted through these waveguides for bending radii down to 2.5 cm.

  11. Diffraction pattern of self-supporting transmission gratings.

    PubMed

    Meekins, J F

    1989-03-15

    Self-supporting transmission gratings suitable for the soft x-ray and extreme ultraviolet must be reinforced by support structures which, if regularly placed, tend to produce undesirable artifacts in the diffraction plane. Because these artifacts appear in the neighborhood of the principal maxima and can be substantial in magnitude, they may confuse the spectrum. Methods are described whereby these unwanted diffraction effects are much reduced or eliminated. In one method, the members of the support structure parallel to the grating slits are placed in a random pattern so that on the average the coherence of the support structure is drastically reduced everywhere. In a second method, these support structure members are distributed pseudorandomly in such a manner that the diffraction pattern of the support structure is completely removed from the diffraction plane. A third method is investigated in which the pseudorandom placement of supports is organized into a repeated pattern, which may be easier to manufacture than the configurations of the first two methods. PMID:20548643

  12. Implementing Transmission Electron Backscatter Diffraction for Atom Probe Tomography.

    PubMed

    Rice, Katherine P; Chen, Yimeng; Prosa, Ty J; Larson, David J

    2016-06-01

    There are advantages to performing transmission electron backscattering diffraction (tEBSD) in conjunction with focused ion beam-based specimen preparation for atom probe tomography (APT). Although tEBSD allows users to identify the position and character of grain boundaries, which can then be combined with APT to provide full chemical and orientation characterization of grain boundaries, tEBSD can also provide imaging information that improves the APT specimen preparation process by insuring proper placement of the targeted grain boundary within an APT specimen. In this report we discuss sample tilt angles, ion beam milling energies, and other considerations to optimize Kikuchi diffraction pattern quality for the APT specimen geometry. Coordinated specimen preparation and analysis of a grain boundary in a Ni-based Inconel 600 alloy is used to illustrate the approach revealing a 50° misorientation and trace element segregation to the grain boundary. PMID:27329309

  13. MOIRE: ground demonstration of a large aperture diffractive transmissive telescope

    NASA Astrophysics Data System (ADS)

    Atcheson, Paul; Domber, Jeanette; Whiteaker, Kevin; Britten, Jerald A.; Dixit, Shamasundar N.; Farmer, Brandon

    2014-08-01

    The desire to field space-based telescopes with apertures in excess of 10 meter diameter is forcing the development of extreme lightweighted large optomechanical structures. Sparse apertures, shell optics, and membrane optics are a few of the approaches that have been investigated and demonstrated. Membrane optics in particular have been investigated for many years. The MOIRE approach in which the membrane is used as a transmissive diffractive optical element (DOE) offers a significant relaxation in the control requirements on the membrane surface figure, supports extreme lightweighting of the primary collecting optic, and provides a path for rapid low cost production of the primary optical elements. Successful development of a powered meter-scale transmissive membrane DOE was reported in 2012. This paper presents initial imaging results from integrating meter-scale transmissive DOEs into the primary element of a 5- meter diameter telescope architecture. The brassboard telescope successfully demonstrates the ability to collect polychromatic high resolution imagery over a representative object using the transmissive DOE technology. The telescope includes multiple segments of a 5-meter diameter telescope primary with an overall length of 27 meters. The object scene used for the demonstration represents a 1.5 km square complex ground scene. Imaging is accomplished in a standard laboratory environment using a 40 nm spectral bandwidth centered on 650 nm. Theoretical imaging quality for the tested configuration is NIIRS 2.8, with the demonstration achieving NIIRS 2.3 under laboratory seeing conditions. Design characteristics, hardware implementation, laboratory environmental impacts on imagery, image quality metrics, and ongoing developments will be presented.

  14. Precise rotational alignment of x-ray transmission diffraction gratings

    SciTech Connect

    Hill, S.L.

    1988-03-28

    Gold transmission diffraction gratings used for x-ray spectroscopy must sometimes be rotationally aligned to the axis of a diagnostic instrument to within sub-milliradian accuracy. We have fabricated transmission diffraction gratings with high line-densities (grating period of 200 and 300 nm) using uv holographic and x-ray lithography. Since the submicron features of the gratings are not optically visible, precision alignment is time consuming and difficult to verify in situ. We have developed a technique to write an optically visible alignment pattern onto these gratings using a scanning electron microscope (SEM). At high magnification (15000 X) several submicron lines of the grating are observable in the SEM, making it possible to write an alignment pattern parallel to the grating lines in an electron-beam-sensitive coating that overlays the grating. We create an alignment pattern by following a 1-cm-long grating line using the SEM's joystick-controlled translation stage. By following the same grating line we are assured the traveled direction of the SEM electron beam is parallel to the grating to better than 10 ..mu..radian. The electron-beam-exposed line-width can be large (5 to 15 ..mu..m wide) depending on the SEM magnification, and is therefore optically visible. The exposed pattern is eventually made a permanent feature of the grating by ion beam etching or gold electroplating. The pattern can be used to accurately align the grating to the axis of a diagnostic instrument. More importantly, the alignment of the grating can be quickly verified in situ.

  15. Dynamical Low-energy Electron Diffraction Analyses of Clean and H-adsorbed Ir(111) Surfaces

    NASA Astrophysics Data System (ADS)

    Matsumoto, Masuaki; Ogura, Syohei; Fukutani, Katsuyuki; Okano, Tatsuo; Okada, Michio

    Structures of Clean and H-adsorbed Ir(111) surfaces were studied by dynamical analyses of low-energy electron diffraction (LEED). LEED pattern for the Clean Ir(111) surface was 1×1. Dynamical analysis of LEED spot intensity vs incident electron enegy (I-V) curves for the clean Ir(111) surface revealed that the layer distance between the 1st and the 2nd layers (d12) equals to 0.2207±0.002 nm, which is almost equal to the bulk value (0.2217 nm). It appears that our result contradicts an previous report, which concluded that d12 equals to 0.216 nm which is 2.6% smaller than the bulk value. However their error bar was so large (±0.01 nm) that it is suggested that our result is the accurate atomic structure of the clean Ir(111) surface. LEED pattern was almost unchanged by H adsorption of 1 ML (1.56×1015 cm-2) at 80 K. The difference between LEED I-V curves before and after hydrogen adsorption was very small and it was impossible to determine the adsorption structure on Ir(111) but it can be conculded that no reconstruction occurs and only a very small relaxation occurs by the adsorption of hydrogen on Ir(111) surface.

  16. Theoretical models of diffraction efficiencies of arc profiled bar transmission grating

    NASA Astrophysics Data System (ADS)

    Shang, Wanli; Mei, Lusheng; Yang, Jiamin

    2012-06-01

    Diffraction efficiencies of transmission grating play important roles in accurate measurement of soft X-ray and grating applications. Circular, horizontal elliptical, and vertical elliptical arc profiled bar models were established from Kirchhoff diffraction theory with the Fraunhofer diffraction approximation to calculate the diffraction efficiencies of arc profiled bar transmission grating. The calculated results were compared with the available data from X-ray Optics web site of Lawrence Berkeley Laboratory's Center. Excellent agreements have been obtained. With these modes the diffraction efficiencies of the particular type of transmission grating having arc profiled bars can be simulated accurately and the best fit bar profiles can be obtained.

  17. Study of mid IR fiber transmission and mode patterns under laser induced stimulated Brillouin scattering

    NASA Technical Reports Server (NTRS)

    Yu, C.; Chong, Yat C.; Zhou, Hongyi

    1990-01-01

    Mid IR fiber transmission and exit radiation mode patterns at various incident CO2 laser power levels appear to be effective diagnostic tools for monitoring laser induced stimulated Brillouin scattering in various mid IR fibers. Such processes are deemed to be essential mechanisms for fiber-optic amplifiers and switches as potential replacements of current repeaters and bistable devices.

  18. The magnetic and crystal structures of Sr2IrO4: A neutron diffraction study

    SciTech Connect

    Ye, Feng; Chi, Songxue; Chakoumakos, Bryan C; Fernandez-Baca, Jaime A; Qi, Tongfei; Cao, Gang

    2013-01-01

    We report a single-crystal neutron diffraction study of the layered Sr2IrO4. This work unambigu- ously determines the magnetic and crystal structures, and reveals that the spin orientation rigidly tracks the staggered rotation of the IrO6 octahedra in Sr2IrO4. The long-range antiferromagnetic order has a canted spin configuration with an ordered moment of 0.208(3) B/Ir site within the basal plane; a detailed examination of the spin canting yields 0.202(3) and 0.049(2) B/site for the a-axis and the b-axis, respectively. It is intriguing that forbidden nuclear reflections of space group I41/acd are also observed in a wide temperature range from 4 K to 600 K, which suggests a reduced crystal structure symmetry. This neutron scattering work provides a direct, well-refined experimen- tal characterization of the magnetic and crystal structures that are crucial to the understanding of the unconventional magnetism existent in this unusual magnetic insulator.

  19. Elimination of higher-order diffraction using zigzag transmission grating in soft x-ray region

    SciTech Connect

    Zang, H. P.; Wang, C. K.; Gao, Y. L.; Zhou, W. M.; Kuang, L. Y.; Wei, L.; Fan, W.; Zhang, W. H.; Zhao, Z. Q.; Cao, L. F.; Gu, Y. Q.; Zhang, B. H.; Jiang, G.; Zhu, X. L.; Xie, C. Q.; Zhao, Y. D.; Cui, M. Q.

    2012-03-12

    We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application.

  20. Elimination of higher-order diffraction using zigzag transmission grating in soft x-ray region

    NASA Astrophysics Data System (ADS)

    Zang, H. P.; Wang, C. K.; Gao, Y. L.; Zhou, W. M.; Kuang, L. Y.; Wei, L.; Fan, W.; Zhang, W. H.; Zhao, Z. Q.; Cao, L. F.; Gu, Y. Q.; Zhang, B. H.; Jiang, G.; Zhu, X. L.; Xie, C. Q.; Zhao, Y. D.; Cui, M. Q.

    2012-03-01

    We present a realization of the sinusoidal transmission function using a series of zigzag-profiled strips where the transmission takes on the binary values 0 and 1 in a two-dimensional distribution. A zigzag transmission grating of 1000 line/mm has been fabricated and demonstrated on the soft x-ray beam of synchrotron radiation. The axial single-order diffraction indicates that the zigzag transmission grating is adequate for spectroscopic application.

  1. Environmental testing and laser transmission results for ruggedized high power IR fiber cables

    NASA Astrophysics Data System (ADS)

    Busse, Lynda; Kung, Frederic; Florea, Catalin; Shaw, Brandon; Aggarwal, Ishwar; Sanghera, Jas

    2013-03-01

    We present successful results of high mid-IR laser power transmission as well as MIL-SPEC environmental testing (thermal cycling and vibration testing) of ruggedized, IR-transmitting chalcogenide glass fiber cables. The cables tested included chalcogenide fiber cables with endfaces imprinted with anti-reflective "moth eye" surfaces, whereby the reflection loss is reduced from about 17% per end to less than 3%. The cables with these moth eye surfaces also show excellent laser damage resistance.

  2. Diffraction Revisited: Position of Diffraction Spots upon Rotation of a Transmission Grating

    ERIC Educational Resources Information Center

    Vollmer, Michael

    2005-01-01

    Diffraction gratings are often used in the laboratory to determine the wavelength of laser light. What happens to the spots on the screen if the grating is rotated in this set-up? The answer is nontrivial and instructive.

  3. A Characteristic Transmission Spectrum for WFC3 IR Water Hosting Exoplanet

    NASA Astrophysics Data System (ADS)

    Swain, Mark R.

    2015-12-01

    Using the 19 published Hubble/WFC3 IR exoplanet transmission spectra, we perform a meta-analysis of the spectral modulation due to water. Because of the heterogeneous nature of these data, in which spectral resolution, calibration approach, and observational method vary, we introduce a formalism to de-bias the estimates of spectral modulation. This analysis finds a characteristic transmission spectrum and examines trends for these water-hosting exoplanets.

  4. He-atom diffraction from nanostructure transmission gratings: The role of imperfections

    NASA Astrophysics Data System (ADS)

    Grisenti, R. E.; Schöllkopf, W.; Toennies, J. P.; Manson, J. R.; Savas, T. A.; Smith, Henry I.

    2000-03-01

    The relative diffraction peak intensities of He atoms with an incident beam energy of 65 meV diffracted from a microfabricated 100 nm-period transmission grating are analyzed using both Fresnel and Fraunhofer diffraction theory. The projected slit width could be varied from 50 nm down to less than 1 nm by inclining the grating at angles up to Θ0=42° with respect to the incident beam. Good agreement between calculated and measured peak intensities, up to the sixth order, is obtained by accounting for random deviations in the slit positions, and averaging over the velocity spread of the incident beam as well as the spatial extent of the nozzle beam source. It is demonstrated that He atom beam diffraction together with simple transmission measurements is an excellent means of characterizing such gratings including a detailed determination of the slit width, the bar shape, and random as well as periodic disorder.

  5. Diffraction and Transmission Synchrotron Imaging at the German Light Source ANKA--Potential Industrial Applications

    SciTech Connect

    Rack, Alexander; Weitkamp, Timm; Helfen, Lukas; Simon, Rolf; Luebbert, Daniel; Baumbach, Tilo

    2009-03-10

    Diffraction and transmission synchrotron imaging methods have proven to be highly suitable for investigations in materials research and non-destructive evaluation. The high flux and spatial coherence of X-rays from modern synchrotron light sources allows one to work using high resolution and different contrast modalities. This article gives a short overview of different transmission and diffraction imaging methods with high potential for industrial applications, now available for commercial access via the German light source ANKA (Forschungszentrum Karlsruhe) and its new department ANKA Commercial Service (ANKA COS, http://www.anka-cos.de)

  6. Quasi-sinusoidal single-order diffraction transmission grating used in x-ray spectroscopy.

    PubMed

    Kuang, Longyu; Cao, Leifeng; Zhu, Xiaoli; Wu, Shunchao; Wang, Zhebin; Wang, Chuanke; Liu, Shenye; Jiang, Shaoen; Yang, Jiamin; Ding, Yongkun; Xie, Changqing; Zheng, Jian

    2011-10-15

    A novel design of quasi-sinusoidal single-order diffraction transmission grating (QSTG) is proposed, which can achieve a line density up to thousands line/millimeter as that of traditional transmission gratings with the current level of nanofabrication technique. We fabricate a 1000 line/mm QSTG using the new design approach, and display the calibration results of such QSTG on the soft x-ray beam of synchrotron radiation. PMID:22002350

  7. Optimizing diffraction efficiency for transmission holographic optical elements with HARMAN holographic materials

    NASA Astrophysics Data System (ADS)

    Smith, Steven L.; Harvey, Karen; Richardson, Martin; Blyth, Jeff

    2011-02-01

    HARMAN technology's new holographic emulsions; red sensitive and green sensitive assisted by smaller grain sizes, novel sensitization and coating technology have been shown to achieve high diffraction efficiencies and narrow band reconstruction capabilities. Authors demonstrate processing optimizations and material behavior characteristics for Transmission image Masters as well as Holographic Optical Elements (HOE's).

  8. New IR imaging modalities for cancer detection and for intra-cell chemical mapping with a sub-diffraction mid-IR s-SNOM.

    PubMed

    Amrania, H; Drummond, L; Coombes, R C; Shousha, S; Woodley-Barker, L; Weir, K; Hart, W; Carter, I; Phillips, C C

    2016-06-23

    We present two new modalities for generating chemical maps. Both are mid-IR based and aimed at the biomedical community, but they differ substantially in their technological readiness. The first, so-called "Digistain", is a technologically mature "locked down" way of acquiring diffraction-limited chemical images of human cancer biopsy tissue. Although it is less flexible than conventional methods of acquiring IR images, this is an intentional, and key, design feature. It allows it to be used, on a routine basis, by clinical personnel themselves. It is in the process of a full clinical evaluation and the philosophy behind the approach is discussed. The second modality is a very new, probe-based "s-SNOM", which we are developing in conjunction with a new family of tunable "Quantum Cascade Laser" (QCL) diode lasers. Although in its infancy, this instrument can already deliver ultra-detailed chemical images whose spatial resolutions beat the normal diffraction limit by a factor of ∼1000. This is easily enough to generate chemical maps of the insides of single cells for the first time, and a range of new possible scientific applications are explored. PMID:27077445

  9. Site-isolated Iridium Complexes on MgO Powder: Individual Ir Atoms Imaged by Scanning Transmission Electron Microscopy

    SciTech Connect

    Uzun, A.; Ortalan, V; D. Browning, N; C. Gates , B

    2009-01-01

    Iridium complexes were synthesized on MgO powder by adsorption of Ir(C{sub 2}H{sub 4}){sub 2}(acac) [acac = acetonylacetonate]; images determined by aberration-corrected scanning transmission electron microscopy show individual Ir atoms, demonstrating that the supported complexes were site-isolated.

  10. Broadband transmission functions for atmospheric IR flux computations and climate studies

    NASA Technical Reports Server (NTRS)

    Chou, M.-D.

    1983-01-01

    In order to reduce the size of precomputed tables which are used in the emissivity approach to computing IR radiation in a climate model, the three-dimensional transmission function in the water vapor bands is defined in this study by a simple regression equation consisting of three two-dimensional parameters. The transmittances in the 9.6 and 15 micron bands are individually parameterized as functions of the amount of scaled absorber. This approach can thus be applied to atmospheres with a variable CO2 concentration.

  11. Single-order transmission diffraction gratings based on dispersion engineered all-dielectric metasurfaces

    NASA Astrophysics Data System (ADS)

    Gupta, Shulabh

    2016-08-01

    A single-order transmission diffraction grating based on dispersion engineered all-dielectric metasurfaces is proposed and its wavelength discriminating properties have been theoretically described and confirmed using numerical simulations. The metasurface is designed using a 2D array of all-dielectric resonators, which emulates a Huygens source configuration to achieve a perfect match to free-space in broad bandwidth. Using a holey dielectric nanodisk structure as the unit cell, the resonant wavelength is tapered across the metasurface to engineer the wavelength dependent spatial phase gradient, to emulate a dispersive prism. Consequently, different wavelengths are steered towards different directions and thus are discriminated on the output image plane. Due to subwavelength periodicities involved, the wavelength discrimination is achieved directly in the zeroth diffraction order of the device, unlike conventional diffraction gratings, thereby providing a high efficiency wavelength discriminating device.

  12. Investigation on Deformation Behavior of Nickel Aluminum Bronze by Neutron Diffraction and Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Xu, Xiaoyan; Wang, Hong; Lv, Yuting; Lu, Weijie; Sun, Guangai

    2016-05-01

    The deformation behavior, deformation microstructures, and generated inter-phase stresses of nickel aluminum bronze were investigated by in situ neutron diffraction instrument and transmission electron microscopy in this paper. Lattice strains calculated by both peak shifting and broadening by Gaussian fitting of α and κ phase neutron diffraction peak profiles at both holding stress conditions and unloaded stress conditions were compared. Twining and stacking faults in α matrix were observed after deformed by different tensile stresses. Compressive internal/residual stress in α matrix and tensile internal stress in κ phase in elasto-plastic region were calculated based on neutron diffraction analysis. The piled-up dislocations around hard κ phases increase with increasing the deformation degree, which raise the stress concentration near α/ κ interface and increase the internal stresses.

  13. Determining Projections of Grain Boundaries from Diffraction Data in Transmission Electron Microscope.

    PubMed

    Kiss, Ákos K; Lábár, János L

    2016-06-01

    Grain boundaries (GB) are characterized by disorientation of the neighboring grains and the direction of the boundary plane between them. A new approach presented here determines the projection of GB that can be used to determine the latter one. The novelty is that an additional parameter of GB is quantified in addition to the ones provided by the orientation maps, namely the width of the projection of the GB is measured from the same set of diffraction patterns that were recorded for the orientation map, without the need to take any additional images. The diffraction patterns are collected in nanobeam diffraction mode in a transmission electron microscope, pixel-by-pixel, from an area containing two neighboring grains and the boundary between them. In our case, the diffraction patterns were recorded using the beam scanning function of a commercially available system (ASTAR). Our method is based on non-negative matrix factorization applied to the mentioned set of diffraction patterns. The method is encoded in a MATLAB environment, making the results easy to interpret and visualize. The measured GB-projection width is used to determine the orientation of the GB-plane, as given in the study by Kiss et al. PMID:27074103

  14. Fabrication of Efficient, Large Aperture Transmission Diffraction Gratings by Ion-Beam Etching

    SciTech Connect

    Nguyen, H T; Bryan, S R; Britten, J A; Perry, M D

    2000-09-14

    The utilization of high-power short pulse laser employing chirped-pulse amplification (CPA) for material processing and inertial confinement research is widely increasing. The performance of these high-power CPA laser system continues to be limited by the ability of the pulse compression gratings to hold up to the high-average-power or high-peak-power of the laser. Pulse compression gratings used in transmission and fabricated out of bulk fused silica have intrinsically the highest laser damage threshold when compared with metal or multilayer dielectric gratings that work in reflection. LLNL has developed processing capability to produce high efficiency fused silica transmission gratings at sizes useful to future Petawatt-class systems, and has demonstrated high efficiency at smaller aperture. This report shows that fused silica diffraction exhibiting >95% efficiency into the -1 diffraction order in transmission (90{sup o} deflection of the incident light, at an incidence angle of 45{sup o} to the grating face). The microstructure of this grating consisted of grooves ion-beam etched to a depth of 1.6 microns with a pitch of 0.75 microns, using a holographically produced photoresist mask that was subsequently stripped away in significance to the fabrication of the small scale high efficiency grating was the development of the processing technology and infrastructure for production of such gratings at up to 65 cm diameter. LLNL is the currently the only location in the world with the ability to coat, interferometrically expose, and ion etch diffractive optics at this aperture. Below, we describe the design, fabrication, performance and, the scaleup process for a producing a high-efficiency transmission grating on a 65 cm fused silica substrate.

  15. Using transmission Kikuchi diffraction to study intergranular stress corrosion cracking in type 316 stainless steels.

    PubMed

    Meisnar, Martina; Vilalta-Clemente, Arantxa; Gholinia, Ali; Moody, Michael; Wilkinson, Angus J; Huin, Nicolas; Lozano-Perez, Sergio

    2015-08-01

    Transmission Kikuchi diffraction (TKD), also known as transmission-electron backscatter diffraction (t-EBSD) is a novel method for orientation mapping of electron transparent transmission electron microscopy specimen in the scanning electron microscope and has been utilized for stress corrosion cracking characterization of type 316 stainless steels. The main advantage of TKD is a significantly higher spatial resolution compared to the conventional EBSD due to the smaller interaction volume of the incident beam with the specimen. Two 316 stainless steel specimen, tested for stress corrosion cracking in hydrogenated and oxygenated pressurized water reactor chemistry, were characterized via TKD. The results include inverse pole figure (IPFZ) maps, image quality maps and misorientation maps, all acquired in very short time (<60 min) and with remarkable spatial resolution (up to 5 nm step size possible). They have been used in order to determine the location of the open crack with respect to the grain boundary, deformation bands, twinning and slip. Furthermore, TKD has been used to measure the grain boundary misorientation and establish a gauge for quantifying plastic deformation at the crack tip and other regions in the surrounding matrix. Both grain boundary migration and slip transfer have been detected as well. PMID:25974882

  16. Effect of thermal treatment and ageing on IR transmission and visible photoluminescence of nanostructured aluminum oxyhydroxide

    NASA Astrophysics Data System (ADS)

    Karlash, A. Yu; Skryshevsky, V. A.; Khodan, A. N.; Kanaev, A. V.; Gayvoronsky, V. Ya

    2012-09-01

    IR transmission and visible photoluminescence (PL) were studied in raw nanoporous aluminum oxyhydroxide (NOA) and in samples after thermal treatment at different temperatures. Structural and chemical modifications of the NOA sample were related to the water content and adsorption/desorption process at the surface. The differences observed in the FTIR spectra in vacuum and after ageing of the samples can be explained by the effects of molecular water and OH- groups on the stability of the low-temperature phases of NOA. A considerable increase in PL intensity and spectrum expansion to longer wavelengths were observed in all NOA samples after water desorption. This was accompanied by strong changes in the PL decay kinetics. Quenching of the fast luminescent decay and low-energy transitions in aged samples were observed after ageing of the samples. Partial passivation of the NOA surface and defective sites under ambient conditions is discussed.

  17. Design of plastic diffractive-refractive compact zoom lenses for visible-near-IR spectrum.

    PubMed

    Greisukh, Grigoriy I; Ezhov, Evgeniy G; Sidyakina, Zoya A; Stepanov, Sergei A

    2013-08-10

    The requirements for selecting the initial scheme for a compact plastic zoom lens are formulated. The main stages of the initial scheme of the transformation, incorporating the diffractive lens and replacement of the lenses' glasses by optical plastics, are presented. The efficiency of the suggested techniques of the optical layout process are demonstrated by using the example of the design and analysis of a zoom lens intended for use in security cameras for day or night vision. PMID:23938440

  18. Predesign of diamond turned refractive/diffractive elements for IR objectives

    NASA Technical Reports Server (NTRS)

    Riedl, Max J.

    1993-01-01

    Diffractive lenses have arrived. Literally hundreds of papers have been published and technology impact reports have been written about the exciting addition of a new tool for the lens designer. Sophisticated computer programs have been developed to aid in the optimization of these diffractive phase profiles for a wide variety of applications. Now, several fabrication methods are being pursued to produce these diffractive elements economically. The best known process is the etching of a multi-level relief grating, known as binary optics. This process uses sets of computer generated lithographic masks. Another, more recently developed method is Dry Photopolymer Embossing (DPE). This replication process uses master holograms. And now, diamond turning is being applied for the machining of these elements. Diamond turning is especially well suited for infrared optics. As any process has advantages and limitations, so has diamond turning. These advantages and limitations are discussed and general guidelines are presented to aid the designer and systems engineer in the project predesign stage.

  19. A Recalibration of the Diffraction Efficiency of the Transmission Grating Spectrometers on EXOSAT

    NASA Astrophysics Data System (ADS)

    Paerels, Frits; Kahn, Steven M.; Wolkovitch, Debra N.

    1998-03-01

    We describe a recalibration of the diffraction efficiency of the transmission gratings on EXOSAT. This recalibration is required in order to quantitatively interpret the soft X-ray spectra obtained with these instruments on Sco X-1. Because this source is extremely bright, the spectra are sensitive enough to reveal residual systematic effects in the grating efficiency. Specifically, we observe short-wavelength radiation dispersed into high (m > 5) spectral orders, which is usually too weak to be detectable. We develop a simple model for the diffraction efficiency and briefly discuss some properties of the efficiency, applicable to X-ray transmission gratings in general. We explore the effect of a new degree of freedom, the cross-sectional shape of the grating bars. We then use a set of preflight calibration spectra to constrain the free parameters of the model. The new efficiency curves are in satisfactory agreement with the calibration data and quantitatively account for the anomalies seen in the spectrum of Sco X-1. We also briefly discuss an empirical zero-order profile shape, appropriate for the analysis of spectra of very bright sources.

  20. Comprehensive Study of Hydrated IDPs: X-Ray Diffraction, IR Spectroscopy and Electron Microscopic Analysis

    NASA Technical Reports Server (NTRS)

    Nakamura, K.; Keller, L. P.; Nakamura, T.; Noguchi, T.; Nozaki, W.; Tomeoka, K.

    2003-01-01

    Chondritic hydrated interplanetary dust particles (IDPs) comprise up to 50% of all IDPs collected in the stratosphere(1). Although much is known about the mineralogy, chemistry and carbon abundance of hydrated IDPs (2-4) controversies still exist regarding their formation, history, and relationship to other primitive solar system materials. Hydrated IDPs are generally believed to be derived from asteroidal sources that have undergone some degree of aqueous alteration. However, the high C contents of hydrated IDPs (by 2 to 6X CI levels (3,4) indicate that they are probably not derived from the same parent bodies sampled by the known chondritic meteorites. We report the comprehensive study of individual hydrated IDPs. The strong depletion in Ca (I) has been used as a diagnostic feature of hydrated IDPs. The particles are embedded in elemental sulfur or low viscosity epoxy and ultramicrotomed thin sections are observed using a transmission electron microscope (TEM) equipped with an energy-dispersive X-ray detector (EDX) followed by other measurements including: 1) FTIR microspectroscopy to understand the significant constraints on the organic functionality and the nature of the C-bearing phases and 2) powder X-ray difiaction using a synchrotron X-ray source to understand the bulk mineralogy of the particles.

  1. Calculation of Projected Bond-Orientational Order Parameters to Quantify Local Symmetries from Transmission Diffraction Data.

    PubMed

    Liu, A C Y; Tabor, R F; Bourgeois, L; de Jonge, M D; Mudie, S T; Petersen, T C

    2016-05-20

    The bond-orientational order parameters introduced by Steinhardt et al. [Phys. Rev. B 28, 784 (1983)] have been an invaluable measurement tool for assessing short-range order in disordered, close-packed assemblies of particles in which the particle positions are known. In many glassy systems the measurement of particle position is not possible or limited (field of view, thickness, resolution) and the bond-orientational order parameters cannot be measured, or adequately sampled. Here we calculate a set of rotationally averaged, projected bond-orientational order parameters that reflect the symmetries of close-packed particle clusters when projected onto a plane. We show by simulation that these parameters are unique fingerprints that can be directly compared to angular correlations in limited-volume, transmission geometry, diffraction patterns from close-packed glassy assemblies. PMID:27258876

  2. Diffraction grating transmission efficiencies for XUV and soft X rays. [for HEAO-B extrasolar astronomy

    NASA Technical Reports Server (NTRS)

    Schnopper, H. W.; Van Speybroeck, L. P.; Delvaille, J. P.; Epstein, A.; Kaellne, E.; Bachrach, R. Z.; Dijkstra, J.; Lantward, L.

    1977-01-01

    The manufacture and properties of a grating intended for extrasolar X-ray studies are described. The manufacturing process uses a split laser beam exposing an interference pattern on the photoresist-coated glass plated with a nickel parting layer. The grating, supporting structure, and mounting frame are electrodeposited on the nickel parting layer, and the final product is lifted from the glass substrate by selective etching of the nickel. A model was derived which relates the number of counts received in a given order m as a function of photon wavenumber. A 4-deg beam line was used to measure the efficiencies of gold transmission gratings for diffraction of X-rays in the range of 45 to 275 eV. The experimental results are in good agreement with model calculations.

  3. Calculation of Projected Bond-Orientational Order Parameters to Quantify Local Symmetries from Transmission Diffraction Data

    NASA Astrophysics Data System (ADS)

    Liu, A. C. Y.; Tabor, R. F.; Bourgeois, L.; de Jonge, M. D.; Mudie, S. T.; Petersen, T. C.

    2016-05-01

    The bond-orientational order parameters introduced by Steinhardt et al. [Phys. Rev. B 28, 784 (1983)] have been an invaluable measurement tool for assessing short-range order in disordered, close-packed assemblies of particles in which the particle positions are known. In many glassy systems the measurement of particle position is not possible or limited (field of view, thickness, resolution) and the bond-orientational order parameters cannot be measured, or adequately sampled. Here we calculate a set of rotationally averaged, projected bond-orientational order parameters that reflect the symmetries of close-packed particle clusters when projected onto a plane. We show by simulation that these parameters are unique fingerprints that can be directly compared to angular correlations in limited-volume, transmission geometry, diffraction patterns from close-packed glassy assemblies.

  4. High temperature x-ray diffraction in transmission under controlled environment

    SciTech Connect

    Margulies, L.; Kramer, M.J.; Williams, J.J.; Deters, E.M.; McCallum, R.W.; Goldman, A.I.; Haeffner, D.R.; Lang, J.C.; Kycia, S.

    1998-12-31

    A compact tube furnace has been developed for high temperature X-ray diffraction studies using high energy synchrotron radiation. The furnace design has a low absorption path in transmission yet allows for a high degree of control of the sample atmosphere and a minimal temperature gradient across the sample. The design allows for a maximum temperature of 1,500 C with a variety of atmospheres including inert, reducing, and oxidizing. Preliminary results obtained at the SRI-CAT 1-ID undulator line (60 keV) at the APS facility and the A2 24 pole wiggler line (45 keV) at CHESS on the Ti{sub 5}Si{sub 3}Z{sub .5} (Z = C, N, O) system will be presented to demonstrate the feasibility of this approach.

  5. Conventional transmission electron microscopy imaging beyond the diffraction and information limits.

    PubMed

    Rosenauer, Andreas; Krause, Florian F; Müller, Knut; Schowalter, Marco; Mehrtens, Thorsten

    2014-08-29

    There are mainly two complementary imaging modes in transmission electron microscopy (TEM): Conventional TEM (CTEM) and scanning TEM (STEM). In the CTEM mode the specimen is illuminated with a plane electron wave, and the direct image formed by the objective lens is recorded in the image plane. STEM is based on scanning the specimen surface with a focused electron beam and collecting scattered electrons with an extended disk or ring-shaped detector. Here we show that combination of CTEM imaging with STEM illumination generally allows extending the point resolution of CTEM imaging beyond the diffraction limit. This new imaging mode improves imaging characteristics, is more robust against chromatic aberration, exhibits direct structural imaging with superior precision, visualizes light elements with excellent contrast, and even allows us to overcome the conventional information limit of a microscope. PMID:25215995

  6. Electron Backscatter Diffraction and Transmission Kikuchi Diffraction Analysis of an Austenitic Stainless Steel Subjected to Surface Mechanical Attrition Treatment and Plasma Nitriding.

    PubMed

    Proust, Gwénaëlle; Retraint, Delphine; Chemkhi, Mahdi; Roos, Arjen; Demangel, Clemence

    2015-08-01

    Austenitic 316L stainless steel can be used for orthopedic implants due to its biocompatibility and high corrosion resistance. Its range of applications in this field could be broadened by improving its wear and friction properties. Surface properties can be modified through surface hardening treatments. The effects of such treatments on the microstructure of the alloy were investigated here. Surface Mechanical Attrition Treatment (SMAT) is a surface treatment that enhances mechanical properties of the material surface by creating a thin nanocrystalline layer. After SMAT, some specimens underwent a plasma nitriding process to further enhance their surface properties. Using electron backscatter diffraction, transmission Kikuchi diffraction, energy dispersive spectroscopy, and transmission electron microscopy, the microstructural evolution of the stainless steel after these different surface treatments was characterized. Microstructural features investigated include thickness of the nanocrystalline layer, size of the grains within the nanocrystalline layer, and depth of diffusion of nitrogen atoms within the material. PMID:26139391

  7. Nanostructure characterisation of flow-formed Cr-Mo-V steel using transmission Kikuchi diffraction technique.

    PubMed

    Birosca, S; Ding, R; Ooi, S; Buckingham, R; Coleman, C; Dicks, K

    2015-06-01

    Nowadays flow-forming has become a desired near net shape manufacturing method as it provides excellent mechanical properties with improved surface finish and significant manufacturing cost reduction. However, the material is subjected to excessive plastic deformation during flow-forming process, generating a very fine and complex microstructure. In addition, the intense dislocation density and residual stress that is generated in the component during processing makes the microstructure characterisation using conventional micro-analytical tools challenging. Thus, the microstructure/property relationship study in such a material is rather difficult. In the present study a flow-formed Cr-Mo-V steel nanostructure and crystallographic texture were characterised by means of Transmission Kikuchi Diffraction (TKD). Here, TKD is shown to be a powerful technique in revealing very fine martensite laths within an austenite matrix. Moreover, fine precipitates in the order of 20-70 nm on the martensite lath boundaries were clearly imaged and characterised. This greatly assisted in understanding the preferable site formation of the carbides in such a complex microstructure. The results showed that the actual TKD spatial resolution was in the range of 5-10 nm using 25 kV for flow-formed Cr-Mo-V steel. PMID:25697460

  8. Elimination of X-Ray Diffraction through Stimulated X-Ray Transmission

    NASA Astrophysics Data System (ADS)

    Wu, B.; Wang, T.; Graves, C. E.; Zhu, D.; Schlotter, W. F.; Turner, J. J.; Hellwig, O.; Chen, Z.; Dürr, H. A.; Scherz, A.; Stöhr, J.

    2016-07-01

    X-ray diffractive imaging with laterally coherent x-ray free-electron laser (XFEL) pulses is increasingly utilized to obtain ultrafast snapshots of matter. Here we report the amazing disappearance of single-shot charge and magnetic diffraction patterns recorded with resonantly tuned, narrow bandwidth XFEL pulses. Our experimental results reveal the exquisite sensitivity of single-shot charge and magnetic diffraction patterns of a magnetic film to the onset of field-induced stimulated elastic x-ray forward scattering. The loss in diffraction contrast, measured over 3 orders of magnitude in intensity, is in remarkable quantitative agreement with a recent theory that is extended to include diffraction.

  9. Blazed high-efficiency x-ray diffraction via transmission through arrays of nanometer-scale mirrors.

    PubMed

    Heilmann, Ralf K; Ahn, Minseung; Gullikson, Eric M; Schattenburg, Mark L

    2008-06-01

    Diffraction gratings are ubiquitous wavelength dispersive elements for photons as well as for subatomic particles, atoms, and large molecules. They serve as enabling devices for spectroscopy, microscopy, and interferometry in numerous applications across the physical sciences. Transmission gratings are required in applications that demand high alignment and figure error tolerances, low weight and size, or a straight-through zero-order beam. However, photons or particles are often strongly absorbed upon transmission, e.g., in the increasingly important extreme ultraviolet (EUV) and soft x-ray band, leading to low diffraction efficiency. We demonstrate the performance of a critical-angle transmission (CAT) grating in the EUV and soft x-ray band that for the first time combines the advantages of transmission gratings with the superior broadband efficiency of blazed reflection gratings via reflection from nanofabricated periodic arrays of atomically smooth nanometer-thin silicon mirrors at angles below the critical angle for total external reflection. The efficiency of the CAT grating design is not limited to photons, but also opens the door to new, sensitive, and compact experiments and applications in atom and neutron optics, as well as for the efficient diffraction of electrons, ions, or molecules. PMID:18545579

  10. Spectral responses of virtual Frisch-grid CdZnTe detectors and their relation to IR microscopy and x-ray diffraction topography data

    NASA Astrophysics Data System (ADS)

    Bolotnikov, A. E.; Babalola, S.; Camarda, G. S.; Cui, Y.; Egarievwe, S. U.; Fochuk, P. M.; Hawrami, R.; Hossain, A.; James, J. R.; Nakonechnyj, I. J.; Yang, Ge; James, R. B.

    2008-08-01

    Virtual Frisch-grid CdZnTe detectors potentially can provide energy resolution close to the statistical limit. However, in real detectors, the quality of the crystals used to fabricate the devices primarily determines energy resolution. In this paper, we report our findings on the spectral response of devices and their relation to material-characterization data obtained using IR microscopy and X-ray diffraction topography.

  11. Single order X-ray diffraction with binary sinusoidal transmission grating

    NASA Astrophysics Data System (ADS)

    Cao, Leifeng

    2013-10-01

    All existing x-ray dispersive devices including crystals, multilayers and diffraction gratings generate spectra in multiple orders, whereas soft x-ray spectroscopy applications usually require only the first order spectrum. The other diffraction orders can overlap and contaminate the first order spectrum of interest. In this letter we describe how an axis-symmetrically-distributed sinusoidal-shaped aperture with binary transmittance values can be used to disperse x-rays and with a superior diffraction pattern where, along its symmetry axis, all higher-order diffractions can be effectively suppressed. Hence this sophisticated dispersive element generates pure soft x-ray spectra in the first diffraction order, free from interference from higher diffraction orders.

  12. Beyond the diffraction limit of optical/IR interferometers. I. Angular diameter and rotation parameters of Achernar from differential phases

    NASA Astrophysics Data System (ADS)

    Domiciano de Souza, A.; Hadjara, M.; Vakili, F.; Bendjoya, P.; Millour, F.; Abe, L.; Carciofi, A. C.; Faes, D. M.; Kervella, P.; Lagarde, S.; Marconi, A.; Monin, J.-L.; Niccolini, G.; Petrov, R. G.; Weigelt, G.

    2012-09-01

    Context. Spectrally resolved long-baseline optical/IR interferometry of rotating stars opens perspectives to investigate their fundamental parameters and the physical mechanisms that govern their interior, photosphere, and circumstellar envelope structures. Aims: Based on the signatures of stellar rotation on observed interferometric wavelength-differential phases, we aim to measure angular diameters, rotation velocities, and orientation of stellar rotation axes. Methods: We used the AMBER focal instrument at ESO-VLTI in its high-spectral resolution mode to record interferometric data on the fast rotator Achernar. Differential phases centered on the hydrogen Br γ line (K band) were obtained during four almost consecutive nights with a continuous Earth-rotation synthesis during ~5 h/night, corresponding to ~60° position angle coverage per baseline. These observations were interpreted with our numerical code dedicated to long-baseline interferometry of rotating stars. Results: By fitting our model to Achernar's differential phases from AMBER, we could measure its equatorial radius Req = 11.6 ± 0.3 R⊙, equatorial rotation velocity Veq = 298 ± 9 km s-1, rotation axis inclination angle i = 101.5 ± 5.2°, and rotation axis position angle (from North to East) PArot = 34.9 ± 1.6°. From these parameters and the stellar distance, the equatorial angular diameter ⌀eq of Achernar is found to be 2.45 ± 0.09 mas, which is compatible with previous values derived from the commonly used visibility amplitude. In particular, ⌀eq and PArot measured in this work with VLTI/AMBER are compatible with the values previously obtained with VLTI/VINCI. Conclusions: The present paper, based on real data, demonstrates the super-resolution potential of differential interferometry for measuring sizes, rotation velocities, and orientation of rotating stars in cases where visibility amplitudes are unavailable and/or when the star is partially or poorly resolved. In particular, we showed

  13. High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB2 and other Ir-B phases

    DOE PAGESBeta

    Xie, Zhilin; Terracciano, Anthony C.; Cullen, David A.; Blair, Richard G.; Orlovskaya, Nina

    2015-05-13

    The formation of IrB2, IrB1.35, IrB1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB2 type IrB2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Ir segregation along disordered domains ofmore » the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.« less

  14. Modification of nanostructured fused silica for use as superhydrophobic, IR-transmissive, anti-reflective surfaces

    NASA Astrophysics Data System (ADS)

    Boyd, Darryl A.; Frantz, Jesse A.; Bayya, Shyam S.; Busse, Lynda E.; Kim, Woohong; Aggarwal, Ishwar; Poutous, Menelaos; Sanghera, Jasbinder S.

    2016-04-01

    In order to mimic and enhance the properties of moth eye-like materials, nanopatterned fused silica was chemically modified to produce self-cleaning substrates that have anti-reflective and infrared transmissive properties. The characteristics of these substrates were evaluated before and after chemical modification. Furthermore, their properties were compared to fused silica that was devoid of surface features. The chemical modification imparted superhydrophobic character to the substrates, as demonstrated by the average water contact angles which exceeded 170°. Finally, optical analysis of the substrates revealed that the infrared transmission capabilities of the fused silica substrates (nanopatterned to have moth eye on one side) were superior to those of the regular fused silica substrates within the visible and near-infrared region of the light spectrum, with transmission values of 95% versus 92%, respectively. The superior transmission properties of the fused silica moth eye were virtually unchanged following chemical modification.

  15. Far IR Transmission Characteristics of Silicon Nitride Films using Fourier Transform Spectroscopy

    NASA Astrophysics Data System (ADS)

    Ferrusca, D.; Castillo-Domínguez, E.; Velázquez, M.; Hughes, D.; Serrano, A.; Torres-Jácome, A.

    2009-12-01

    We are fabricating amorphous Silicon (a-Si) bolometers doped with boron with a measured NEP˜1.5×10-16 W/Hz1/2 suitable for use in millimeter and sub-millimeter astronomy. In this paper we present the preliminary results of the absorber optimization for the a-Si bolometers. A film of Silicon Nitride (SiN), deposited by LPCVD (Low Pressure Chemical Vapor Deposition) process at INAOE, with or without metallic coating is used as a weak thermal link to the heat sink as well as an absorber. We have measured the transmission spectrum of thin films of SiN in the range of 200 to 1000 GHz using Fourier Transform Spectroscopy (FTS) and a bolometric system with a NEP˜1.26×10-13. The transmission of thin films of SiN with a thickness of 0.4 μn has been measured at temperatures of 290 K and 4 K. The uncoated SiN films have a transmission of 80% and we expect a 50% transmission for the metallic (e.g. Titanium) coated films.

  16. Complete analysis of a transmission electron diffraction pattern of a MoS2-graphite heterostructure.

    PubMed

    Adrian, Marlene; Senftleben, Arne; Morgenstern, Silvio; Baumert, Thomas

    2016-07-01

    The combination of various 2D layered materials in multilayer heterostructures arises great interest in the current science. Due to the large variety of electronic properties of the group of 2D layered materials the combination opens a new pathway towards ultrasmall electronic devices. In this contribution we present a full mathematical description of multilayer heterostructure samples and their diffraction patterns including a proposal of a consistent assignment of the superstructure diffraction spots. A 27nm thick MoS2-graphite heterostructure was produced and fully analysed with the methods presented in this paper. PMID:27107328

  17. Nonlinear absorption and transmission properties of Ge, Te and InAs using tuneable IR FEL

    SciTech Connect

    Amirmadhi, F.; Becker, K.; Brau, C.A.

    1995-12-31

    Nonlinear absorption properties of Ge, Te and InAs are being investigated using the transmission of FEL optical pulses through these semiconductors (z-scan method). Wavelength, intensity and macropulse dependence are used to differentiate between two-photon and free-carrier absorption properties of these materials. Macropulse dependence is resolved by using a Pockles Cell to chop the 4-{mu}s macropulse down to 100 ns. Results of these experiments will be presented and discussed.

  18. Analytical theory of extraordinary transmission through metallic diffraction screens perforated by small holes.

    PubMed

    Marqués, R; Mesa, F; Jelinek, L; Medina, F

    2009-03-30

    In this letter, the problem of extraordinary (ET) transmission of electromagnetic waves through opaque screens perforated with subwave-length holes is addressed from an analytical point of view. Our purpose was to find a closed-form expression for the transmission coefficient in a simple case in order to explore and clarify, as much as possible, the physical background of the phenomenon. The solution of this canonical example, apart from matching quite well with numerical simulations given by commercial solvers, has provided new insight in extraordinary transmission as well as Wood's anomaly. Thus, our analysis has revealed that one of the key factors behind ET is the continuous increase of excess electric energy around the holes as the frequency approaches the onset of some of the higher-order modes associated with the periodicity of the screen. The same analysis also helps to clarify the role of surface modes -or spoof plasmons- in the onset of ET. PMID:19333324

  19. Hubble space telescope near-ir transmission spectroscopy of the super-Earth HD 97658B

    SciTech Connect

    Knutson, Heather A.; Dragomir, Diana; Kreidberg, Laura; Bean, Jacob L.; Kempton, Eliza M.-R.; McCullough, P. R.; Fortney, Jonathan J.; Gillon, Michael; Homeier, Derek; Howard, Andrew W.

    2014-10-20

    Recent results from the Kepler mission indicate that super-Earths (planets with masses between 1-10 times that of the Earth) are the most common kind of planet around nearby Sun-like stars. These planets have no direct solar system analogue, and are currently one of the least well-understood classes of extrasolar planets. Many super-Earths have average densities that are consistent with a broad range of bulk compositions, including both water-dominated worlds and rocky planets covered by a thick hydrogen and helium atmosphere. Measurements of the transmission spectra of these planets offer the opportunity to resolve this degeneracy by directly constraining the scale heights and corresponding mean molecular weights of their atmospheres. We present Hubble Space Telescope near-infrared spectroscopy of two transits of the newly discovered transiting super-Earth HD 97658b. We use the Wide Field Camera 3's (WFC3) scanning mode to measure the wavelength-dependent transit depth in 30 individual bandpasses. Our averaged differential transmission spectrum has a median 1σ uncertainty of 23 ppm in individual bins, making this the most precise observation of an exoplanetary transmission spectrum obtained with WFC3 to date. Our data are inconsistent with a cloud-free solar metallicity atmosphere at the 10σ level. They are consistent at the 0.4σ level with a flat line model, as well as effectively flat models corresponding to a metal-rich atmosphere or a solar metallicity atmosphere with a cloud or haze layer located at pressures of 10 mbar or higher.

  20. Features of the ISO-25498: method of selected area electron diffraction analysis in transmission electron microscopy.

    PubMed

    Liu, Delu

    2013-08-01

    International standard ISO-25498 specifies the method of selected area electron diffraction (SAED) analysis in TEM. It is applicable to the acquisition of SAED patterns, indexing the patterns and calibration of diffraction constant. Several features of this standard are introduced. As an example of the applications, phosphide with nanometer scale in a low-carbon steel produced by compact strip production process was analyzed by SAED and EDX. The phosphide precipitates in the steel are identified as M x P, where x is 2-3 and M is Fe, Ti, Cr, or Ni. It possesses a hexagonal lattice with lattice parameter a = 0.609 nm and c = 0.351 nm. PMID:23920207

  1. Turbine engine exhaust gas measurements using in-situ FT-IR emission/transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Marran, David F.; Cosgrove, Joseph E.; Neira, Jorge; Markham, James R.; Rutka, Ronald; Strange, Richard R.

    2001-02-01

    12 An advanced multiple gas analyzer based on in-situ Fourier transform infrared spectroscopy has been used to successfully measure the exhaust plume composition and temperature of an operating gas turbine engine at a jet engine test stand. The sensor, which was optically coupled to the test cell using novel broadband hollow glass waveguides, performed well in this harsh environment (high acoustical noise and vibration, considerable temperature swings in the ambient with engine operation), providing quantitative gas phase information. Measurements were made through the diameter of the engine's one meter exhaust plume, about 0.7 meters downstream of the engine exit plane. The sensor performed near simultaneous infrared transmission and infrared emission measurements through the centerline of the plume. Automated analysis of the emission and transmission spectra provided the temperature and concentration information needed for engine tuning and control that will ensure optimal engine operation and reduced emissions. As a demonstration of the utility and accuracy of the technique, carbon monoxide, nitric oxide, water, and carbon dioxide were quantified in spite of significant variations in the exhaust gas temperature. At some conditions, unburned fuel, particulates (soot/fuel droplets), methane, ethylene and aldehydes were identified, but not yet quantified.

  2. High precision two-dimensional strain mapping in semiconductor devices using nanobeam electron diffraction in the transmission electron microscope

    SciTech Connect

    Baumann, Frieder H.

    2014-06-30

    A classical method used to characterize the strain in modern semiconductor devices is nanobeam diffraction (NBD) in the transmission electron microscope. One challenge for this method lies in the fact that the smaller the beam becomes, the more difficult it becomes to analyze the resulting diffraction spot pattern. We show that a carefully designed fitting algorithm enables us to reduce the sampling area for the diffraction patterns on the camera chip dramatically (∼1/16) compared to traditional settings without significant loss of precision. The resulting lower magnification of the spot pattern permits the presence of an annular dark field detector, which in turn makes the recording of images for drift correction during NBD acquisition possible. Thus, the reduced sampling size allows acquisition of drift corrected NBD 2D strain maps of up to 3000 pixels while maintaining a precision of better than 0.07%. As an example, we show NBD strain maps of a modern field effect transistor (FET) device. A special filtering feature used in the analysis makes it is possible to measure strain in silicon devices even in the presence of other crystalline materials covering the probed area, which is important for the characterization of the next generation of devices (Fin-FETs).

  3. Strain mapping at the nanoscale using precession electron diffraction in transmission electron microscope with off axis camera

    SciTech Connect

    Vigouroux, M. P.; Delaye, V.; Bernier, N.; Lafond, D.; Audoit, G.; Bertin, F.; Cipro, R.; Baron, T.; Martin, M.; Rouvière, J. L.; Chenevier, B.

    2014-11-10

    Precession electron diffraction is an efficient technique to measure strain in nanostructures by precessing the electron beam, while maintaining a few nanometre probe size. Here, we show that an advanced diffraction pattern treatment allows reproducible and precise strain measurements to be obtained using a default 512 × 512 DigiSTAR off-axis camera both in advanced or non-corrected transmission electron microscopes. This treatment consists in both projective geometry correction of diffraction pattern distortions and strain Delaunay triangulation based analysis. Precision in the strain measurement is improved and reached 2.7 × 10{sup −4} with a probe size approaching 4.2 nm in diameter. This method is applied to the study of the strain state in InGaAs quantum-well (QW) devices elaborated on Si substrate. Results show that the GaAs/Si mismatch does not induce in-plane strain fluctuations in the InGaAs QW region.

  4. A novel approach to tunable diffractive transmission gratings based on dielectric elastomer actuators

    NASA Astrophysics Data System (ADS)

    Kollosche, Matthias; Döring, Sebastian; Kofod, Guggi; Stumpe, Joachim

    2010-04-01

    Dielectric elastomer actuators (DEA) of poly-styrene-ethylene-butadiene-styrene (SEBS) and commonly used VHB4910 tape were studied for voltage tunable optical transmission gratings. A new geometry is proposed, in which the grating is placed in an area without electrodes, permitting for light transmission through the device. Experiments were performed to implement surface relief gratings on DEA films from pattern masters made from holographic recorded gratings. Since the actuation strain of the DEA depends strongly on the boundary conditions, the desired voltage-controllable deformation of the grating can be achieved by choosing suitable manufacturing parameters. Conditions were found permitting a shift of up to 9 % in a 1 μm grating. A model based on independently measured material parameters is shown to describe the optical behavior.

  5. Engineered second-harmonic diffraction from highly transmissive metasurfaces composed of complementary split-ring resonators.

    PubMed

    Yang, Xin; Zhang, Chi; Wan, Mingjie; Chen, Zhuo; Wang, Zhenlin

    2016-07-01

    We theoretically and experimentally investigated the optical second-harmonic (SH) diffraction from metasurfaces based on gold complementary split-ring resonators (CSRRs). We have demonstrated that the generated SH currents are mostly parallel to the incident polarization and are asymmetric with respect to the base of a CSRR, thus allowing us to impose the phase change of π on the SH radiation by reversing the CSRR's orientation. We verified this concept of geometry-induced nonlinear phase by designing and fabricating a nonlinear metasurface consisting of supercells of CSRRs with opposite orientations that can function as a SH beam splitter. The ability to control the phase of the local nonlinearity coupled with the high transmittance at both fundamental and SHG wavelengths makes the CSRRs good candidates for the construction of highly efficient three-dimensional nonlinear metamaterials and suitable for applications in nonlinear beam shaping. PMID:27367070

  6. Airborne detection of natural gas leaks from transmission pipelines by using a laser system operating in visual, near-IR, and mid-IR wavelength bands

    NASA Astrophysics Data System (ADS)

    Ershov, Oleg V.; Klimov, Alexey G.; Vavilov, Vladimir P.

    2006-04-01

    An airborne gas detection IR system which includes a laser, infrared imager and video-recorder is described. The sensitivity of the system to leaks from ground pipelines by the laser channel is about 100 ppm*m at 100 m (by methane). The IR thermographic channel plays an auxiliary role and the video channel allows better coordinate positioning of detected gas leaks in conjunction with a built-in GPS device.

  7. Transmission X-ray Diffraction (XRD) Patterns Relevant to the MSL Chemin Amorphous Component: Sulfates And Silicates

    NASA Technical Reports Server (NTRS)

    Morris, R. V.; Rampe, E. B.; Graff, T. G.; Archer, P. D., Jr.; Le, L.; Ming, D. W.; Sutter, B.

    2015-01-01

    The Mars Science Laboratory (MSL) CheMin instrument on the Curiosity rover is a transmission X-ray diffractometer (Co-Kalpha radiation source and a approx.5deg to approx.52deg 2theta range) where the analyzed powder samples are constrained to have discrete particle diameters <150 microns by a sieve. To date, diffraction patterns have been obtained for one basaltic soil (Rocknest (RN)) and four drill fines of coherent rock (John Klein (JK), Cumberland (CB), Windjana (WJ), and Confidence Hills (CH)). The CheMin instrument has detected and quantified the abundance of both primary igneous (e.g., feldspar, olivine, and pyroxene) and secondary (e.g., Ca-sulfates, hematite, akaganeite, and Fe-saponite) minerals. The diffraction patterns of all CheMin samples are also characterized by a broad diffraction band centered near 30deg 2theta and by increasing diffraction intensity (scattering continuum) from approx.15deg to approx.5deg, the 2theta minimum. Both the broad band and the scattering continuum are attributed to the presence of an XRD amorphous component. Estimates of amorphous component abundance, based on the XRD data itself and on mass-balance calculations using APXS data crystalline component chemistry derived from XRD data, martian meteorites, and/or stoichiometry [e.g., 6-9], range from approx.20 wt.% to approx.50 wt.% of bulk sample. The APXSbased calculations show that the amorphous component is rich in volatile elements (esp. SO3) and is not simply primary basaltic glass, which was used as a surrogate to model the broad band in the RN CheMin pattern. For RN, the entire volatile inventory (except minor anhydrite) is assigned to the amorphous component because no volatile-bearing crystalline phases were reported within detection limits [2]. For JK and CB, Fesaponite, basanite, and akaganeite are volatile-bearing crystalline components. Here we report transmission XRD patterns for sulfate and silicate phases relevant to interpretation of MSL-CheMin XRD amorphous

  8. Guided Wave Propagation and Diffraction in Plates with Obstacles: Resonance Transmission and Trapping Mode Effects

    NASA Astrophysics Data System (ADS)

    Glushkov, E. V.; Glushkova, N. V.; Eremin, A. A.; Lammering, R.

    The paper is based on the authors' report at ICU-2015 giving the idea of the semi-analytical integral equation approach to a physically clear simulation of wave phenomena in composite plate-like structures with local inhomogeneities. On this basis, a set of low-cost computer models for a reliable near- and far-field analysis had been developed and experimentally validated. Their abilities have been illustrated with examples of structural frequency response and radiation pattern diagrams for guided waves (GW) generated by piezoelectric wafer active sensors (PWAS); the reconstruction of effective elastic moduli of fiber-reinforced composites; the PWAS frequency tuning with accounting for the radiation directivity induced by anisotropy; and the effects of wave energy resonance transmission and trapping. Some of these examples have been already discussed in journal articles. Therefore, the present paper concentrates on the recent results of resonance GW interaction with deep surface notches and buried cavities.

  9. Coded aperture x-ray diffraction imaging with transmission computed tomography side-information

    NASA Astrophysics Data System (ADS)

    Odinaka, Ikenna; Greenberg, Joel A.; Kaganovsky, Yan; Holmgren, Andrew; Hassan, Mehadi; Politte, David G.; O'Sullivan, Joseph A.; Carin, Lawrence; Brady, David J.

    2016-03-01

    Coded aperture X-ray diffraction (coherent scatter spectral) imaging provides fast and dose-efficient measurements of the molecular structure of an object. The information provided is spatially-dependent and material-specific, and can be utilized in medical applications requiring material discrimination, such as tumor imaging. However, current coded aperture coherent scatter spectral imaging system assume a uniformly or weakly attenuating object, and are plagued by image degradation due to non-uniform self-attenuation. We propose accounting for such non-uniformities in the self-attenuation by utilizing an X-ray computed tomography (CT) image (reconstructed attenuation map). In particular, we present an iterative algorithm for coherent scatter spectral image reconstruction, which incorporates the attenuation map, at different stages, resulting in more accurate coherent scatter spectral images in comparison to their uncorrected counterpart. The algorithm is based on a spectrally grouped edge-preserving regularizer, where the neighborhood edge weights are determined by spatial distances and attenuation values.

  10. Experimental Verification of Overcoming the Diffraction Limit with a Volumetric Veselago-Pendry Transmission-Line Lens

    NASA Astrophysics Data System (ADS)

    Zhu, Jiang; Eleftheriades, George V.

    2008-07-01

    A fully printed Veselago-Pendry lens (isotropic n=-1, ɛr=-1, μr=-1) is presented which is based on transmission-line metamaterials. The lens is constructed in a parallel-plate environment at 1.569 GHz and without any embedded sources and achieves a resolution better than the diffraction limit (full width half power of 0.235λ). Because the lens is low loss (<0.3dB per unit cell), the focused fields are dominated by the evanescent components which dictates that subwavelength tightening of the beam is achieved only in the transverse and not the longitudinal direction. The demonstrated lens is quarter-wavelength thick thus allowing ample “working distance” between the subject/image and the lens.

  11. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    NASA Astrophysics Data System (ADS)

    Parsons, R.; Yanai, T.; Kishimoto, H.; Kato, A.; Ohnuma, M.; Suzuki, K.

    2015-05-01

    In order to better understand the origin of field-induced anisotropy (Ku) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe94-xNb6Bx (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λs) of nanocrystalline Fe94-xNb6Bx was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λs values for the bcc-Fe nanocrystallites (-5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured Ku values (˜100 J/m3) was estimated via the inverse magnetostrictive effect using the measured λs values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce Ku under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced Ku cannot be explained through the magnetoelastic effect.

  12. Molecular structure of actein: 13C CPMAS NMR, IR, X-ray diffraction studies and theoretical DFT-GIAO calculations

    NASA Astrophysics Data System (ADS)

    Jamróz, Marta K.; Bąk, Joanna; Gliński, Jan A.; Koczorowska, Agnieszka; Wawer, Iwona

    2009-09-01

    Actein is a prominent triterpene glycoside occurring in Actaea racemosa. The triterpene glycosides are believed to be responsible for the estrogenic activity of an extract prepared from this herb. We determined in the crystal structure of actein by X-ray crystallography to be monoclinic P2(1) chiral space group. Refining the disorder, we determined 70% and 30% of contributions of ( S)- and ( R)-actein, respectively. The IR and Raman spectra suggest that actein forms at least four different types of hydrogen bonds. The 13C NMR spectra of actein were recorded both in solution and solid state. The 13C CPMAS spectrum of actein displays multiplet signals, in agreement with the crystallographic data. The NMR shielding constants were calculated for actein using GIAO approach and a variety of basis sets: 6-31G**, 6-311G**, 6-31+G**, cc-pVDZ, cc-pVDZ-su1 and 6-31G**-su1, as well as IGLO approach combined with the IGLO II basis set. The best results (RMSD of 1.6 ppm and maximum error of 3.4 ppm) were obtained with the 6-31G**-su1 basis set. The calculations of the shielding constants are helpful in the interpretation of the 13C CPMAS NMR spectra of actein and actein's analogues.

  13. Mechanochemical synthesis in copper(II) halide/pyridine systems: single crystal X-ray diffraction and IR spectroscopic studies.

    PubMed

    Bowmaker, Graham A; Di Nicola, Corrado; Pettinari, Claudio; Skelton, Brian W; Somers, Neil; White, Allan H

    2011-05-14

    Whereas complexes of divalent metal halides (X = Cl, Br, I) with/from pyridine commonly crystallise as trans-[M(py)(4)X(2)]·2py, M on a site of 222 symmetry in space group Ccca, true for CuCl(2) and CuBr(2) in particular, the copper(II) iodide adduct is of the form [Cu(py)(4)I]I·2py, Cu on a site of mm2 symmetry in space group Cmcm, and five-coordinate (square-pyramidal), the same cationic species also being found in 2[Cu(py)(4)I](I(3))·[(py)(2)Cu(μ-I)(2)Cu(py)(2)] (structurally defined). Bromide or N-thiocyanate may be substituted for the unbound iodide ion in the solvated salt, resulting in complexes which crystallize in space group Ccca, but with both anions and the metal atom disordered. In [Cu(py)(4)(I(3))(2)], a pair of long Cu···I contacts approach a square-planar Cu(py)(4) array. Assignments of the ν(CuN) and ν(CuX) (X = Br, I, SCN) bands in the far-IR spectra are made, the latter with the aid of analogous assignments for [Cu(py)(2)X(2)] (X = Cl, Br), which show a dependence of ν(CuX) on the Cu-X bond length that is very similar to that determined previously for copper(i) halide complexes. The structure of the adventitious complex [(trans-)(H(2)O)(py)(4)CuClCu(py)(4)](I(3))(3)·H(2)O is also recorded, with six- and five-coordinate copper atoms; rational synthesis provides [{Cu(py)(4)}(2)(μ-Cl)](I(3))(3)·H(2)O with one water molecule less. In [{Cu(py)(4)Cl}((∞|∞))](I(3))·3py, square pyramidal [Cu(py)(4)Cl](+) cations, assisted by Cl···Cu interactions, stack to give rise to infinite polymeric strings. Several of these compounds were prepared mechanochemically, illustrating the applicability of this method to syntheses involving redox reactions as well as to complex syntheses involving up to five components. The totality of results demonstrates that the [Cu(II)(py)(4)] entity can be stabilized in an unexpectedly diverse range of mononuclear and multinuclear complexes through the presence of lattice pyridine molecules, the bulky triiodide

  14. Mesoporous silica nanoparticle supported PdIr bimetal catalyst for selective hydrogenation, and the significant promotional effect of Ir

    NASA Astrophysics Data System (ADS)

    Yang, Hui; Huang, Chao; Yang, Fan; Yang, Xu; Du, Li; Liao, Shijun

    2015-12-01

    A mesoporous silica nanoparticle (MSN) supported bimetal catalyst, PdIr/MSN, was prepared by a facile impregnation and hydrogen reduction method. The strong promotional effect of Ir was observed and thoroughly investigated. At the optimal molar ratio of Ir to Pd (NIr/NPd = 0.1), the activity of PdIr0.1/MSN was up to eight times and 28 times higher than that of monometallic Pd/MSN and Ir/MSN, respectively. The catalysts were characterized comprehensively by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and hydrogen temperature programmed reduction, which revealed that the promotional effect of Ir may be due to the enhanced dispersion of active components on the MSN, and to the intensified Pd-Ir electronic interaction caused by the addition of Ir.

  15. Direct evidence of a zigzag spin-chain structure in the honeycomb lattice: A neutron and x-ray diffraction investigation of single-crystal Na2IrO3

    SciTech Connect

    Ye, Feng; Chi, Songxue; Cao, Huibo; Chakoumakos, Bryan C; Fernandez-Baca, Jaime A; Custelcean, Radu; Qi, Tongfei; Korneta, O. B.; Cao, Gang

    2012-01-01

    We have combined single crystal neutron and x-ray diffractions to investigate the magnetic and crystal structures of the honeycomb lattice $\\rm Na_2IrO_3$. The system orders magnetically below $18.1(2)$~K with Ir$^{4+}$ ions forming zigzag spin chains within the layered honeycomb network with ordered moment of $\\rm 0.22(1)~\\mu_B$/Ir site. Such a configuration sharply contrasts the N{\\'{e}}el or stripe states proposed in the Kitaev-Heisenberg model. The structure refinement reveals that the Ir atoms form nearly ideal 2D honeycomb lattice while the $\\rm IrO_6$ octahedra experience a trigonal distortion that is critical to the ground state. The results of this study provide much-needed experimental insights into the magnetic and crystal structure crucial to the understanding of the exotic magnetic order and possible topological characteristics in the 5$d$-electron based honeycomb lattice.

  16. Induced magnetic anisotropy in Si-free nanocrystalline soft magnetic materials: A transmission x-ray diffraction study

    SciTech Connect

    Parsons, R. Suzuki, K.; Yanai, T.; Kishimoto, H.; Kato, A.; Ohnuma, M.

    2015-05-07

    In order to better understand the origin of field-induced anisotropy (K{sub u}) in Si-free nanocrystalline soft magnetic alloys, the lattice spacing of the bcc-Fe phase in nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} (x = 10, 12, 14) alloys annealed under an applied magnetic field has been investigated by X-ray diffraction in transmission geometry (t-XRD) with the diffraction vector parallel and perpendicular to the field direction. The saturation magnetostriction (λ{sub s}) of nanocrystalline Fe{sub 94−x}Nb{sub 6}B{sub x} was found to increase linearly with the volume fraction of the residual amorphous phase and is well described by taking into account the volume-weighted average of two local λ{sub s} values for the bcc-Fe nanocrystallites (−5 ± 2 ppm) and the residual amorphous matrix (+8 ± 2 ppm). The lattice distortion required to produce the measured K{sub u} values (∼100 J/m{sup 3}) was estimated via the inverse magnetostrictive effect using the measured λ{sub s} values and was compared to the lattice spacing estimations made by t-XRD. The lattice strain required to produce K{sub u} under the magnetoelastic model was not observed by the t-XRD experiments and so the findings of this study suggest that the origin of magnetic field induced K{sub u} cannot be explained through the magnetoelastic effect.

  17. Beyond the diffraction limit of optical/IR interferometers. II. Stellar parameters of rotating stars from differential phases

    NASA Astrophysics Data System (ADS)

    Hadjara, M.; Domiciano de Souza, A.; Vakili, F.; Jankov, S.; Millour, F.; Meilland, A.; Khorrami, Z.; Chelli, A.; Baffa, C.; Hofmann, K.-H.; Lagarde, S.; Robbe-Dubois, S.

    2014-09-01

    , PArot = 65.6° ± 5°, for Fomalhaut. They were found to be compatible with previously published values from differential phase and visibility measurements, while we were able to determine, for the first time, the inclination angle i of Fomalhaut (i = 90° ± 9°) and δ Aquilae (i = 81° ± 13°), and the rotation-axis position angle PArot of δ Aquilae. Conclusions: Beyond the theoretical diffraction limit of an interferometer (ratio of the wavelength to the baseline), spatial super resolution is well suited to systematically estimating the angular diameters of rotating stars and their fundamental parameters with a few sets of baselines and the Earth-rotation synthesis provided a high enough spectral resolution. Based on observations performed at the European Southern Observatory, Chile, under ESO AMBER-consortium GTO program IDs 084.D-0456 081.D-0293 and 082.C-0376.Figure 5 is available in electronic form at http://www.aanda.org

  18. Curcumin-β-cyclodextrin inclusion complex: stability, solubility, characterisation by FT-IR, FT-Raman, X-ray diffraction and photoacoustic spectroscopy, and food application.

    PubMed

    Mangolim, Camila Sampaio; Moriwaki, Cristiane; Nogueira, Ana Claudia; Sato, Francielle; Baesso, Mauro Luciano; Neto, Antônio Medina; Matioli, Graciette

    2014-06-15

    Curcumin was complexed with β-CD using co-precipitation, freeze-drying and solvent evaporation methods. Co-precipitation enabled complex formation, as indicated by the FT-IR and FT-Raman techniques via the shifts in the peaks that were assigned to the aromatic rings of curcumin. In addition, photoacoustic spectroscopy and X-ray diffraction, with the disappearance of the band related to aromatic rings, by Gaussian fitting, and modifications in the spectral lines, respectively, also suggested complex formation. The possible complexation had an efficiency of 74% and increased the solubility of the pure colourant 31-fold. Curcumin-β-CD complex exhibited a sunlight stability 18% higher than the pure colourant. This material was stable to pH variations and storage at -15 and 4°C. With an isothermal heating at 100 and 150°C for 2h, the material exhibited a colour retention of approximately 99%. The application of curcumin-β-CD complex in vanilla ice creams intensified the colour of the products and produced a great sensorial acceptance. PMID:24491741

  19. Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands.

    PubMed

    Heilmann, Ralf K; Ahn, Minseung; Bruccoleri, Alex; Chang, Chih-Hao; Gullikson, Eric M; Mukherjee, Pran; Schattenburg, Mark L

    2011-04-01

    We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 μm were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of ∼50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher. PMID:21460902

  20. Diffraction efficiency of 200-nm-period critical-angle transmission gratings in the soft x-ray and extreme ultraviolet wavelength bands

    SciTech Connect

    Heilmann, Ralf K.; Ahn, Minseung; Bruccoleri, Alex; Chang, Chih-Hao; Gullikson, Eric M.; Mukherjee, Pran; Schattenburg, Mark L.

    2011-04-01

    We report on measurements of the diffraction efficiency of 200-nm-period freestanding blazed transmission gratings for wavelengths in the 0.96 to 19.4 nm range. These critical-angle transmission (CAT) gratings achieve highly efficient blazing over a broad band via total external reflection off the sidewalls of smooth, tens of nanometer thin ultrahigh aspect-ratio silicon grating bars and thus combine the advantages of blazed x-ray reflection gratings with those of more conventional x-ray transmission gratings. Prototype gratings with maximum depths of 3.2 and 6 {mu}m were investigated at two different blaze angles. In these initial CAT gratings the grating bars are monolithically connected to a cross support mesh that only leaves less than half of the grating area unobstructed. Because of our initial fabrication approach, the support mesh bars feature a strongly trapezoidal cross section that leads to varying CAT grating depths and partial absorption of diffracted orders. While theory predicts broadband absolute diffraction efficiencies as high as 60% for ideal CAT gratings without a support mesh, experimental results show efficiencies in the range of {approx}50-100% of theoretical predictions when taking the effects of the support mesh into account. Future minimization of the support mesh therefore promises broadband CAT grating absolute diffraction efficiencies of 50% or higher.

  1. Diphosphine- and CO-Induced Fragmentation of Chloride-bridged Dinuclear Complex and Cp*Ir(mu-Cl)(3)Re(CO)(3) and Attempted Synthesis of Cp*Ir(mu-Cl)(3)Mn(CO)(3): Spectroscopic Data and X-ray Diffraction Structures of the Pentamethylcyclopentadienyl Compounds [Cp*IrCl{(Z)-Ph2PCH = CHPPh2}][Cl]center dot 2CHCl(3) and Cp*Ir(CO)Cl-2

    SciTech Connect

    Hammons, Casey; Wang, Xiaoping; Nesterov, Vladimir; Richmond, Michael G.

    2010-01-01

    The confacial bioctahedral compound Cp*Ir(mu-Cl)(3)Re(CO)(3) (1) undergoes rapid fragmentation in the presence of the unsaturated diphosphine ligand (Z)-Ph2PCH = CHPPh2 to give the mononuclear compounds [Cp*IrCl {(Z)-Ph2PCH = CHPPh2}][Cl] (2) and fac-ClRe(CO)(3)[(Z)-Ph2PCH = CHPPh2] (3). 2 has been characterized by H-1 and P-31 NMR spectroscopy and X-ray diffraction analysis. 2 center dot 2CHCl(3) crystallizes in the monoclinic space group C2/c, a = 35.023 (8) angstrom, b = 10.189 (2) angstrom, c = 24.003 (6) angstrom, b = 103.340 (3), V = 8,335 (3) angstrom 3, Z = 8, and d(calc) = 1.647 Mg/m(3); R = 0.0383, R-w = 0.1135 for 8,178 reflections with I> 2 sigma(I). The Ir(III) center in 2 exhibits a six-coordinate geometry and displays a chelating diphosphine group. Compound 1 reacts with added CO with fragmentation to yield the known compounds Cp*Ir(CO)Cl-2 (4) and ClRe(CO)(5) (5) in near quantitative yield by IR spectroscopy. Using the protocol established by our groups for the synthesis of 1, we have explored the reaction of [Cp*IrCl2](2) with ClMn(CO)(5) as a potential route to Cp*Ir(mu-Cl)(3)Mn(CO)(3); unfortunately, 4 was the only product isolated from this reaction. The solid-state structure of 4 was determined by X-ray diffraction analysis. 4 crystallizes in the triclinic space group P-1, a = 7.4059 (4) angstrom, b = 7.8940 (4) angstrom, c = 11.8488 (7) angstrom, alpha = 80.020 (1), beta = 79.758 (1), gamma = 68.631 (1), V = 630.34 (6) angstrom(3), Z = 2, and d(calc) = 2.246 Mg/m(3); R = 0.0126, R-w = 0.0329 for 2,754 reflections with I> 2 sigma(I). The expected three-legged piano-stool geometry in 4 has been crystallographically confirmed.

  2. Good performances but short lasting efficacy of Actellic 50 EC Indoor Residual Spraying (IRS) on malaria transmission in Benin, West Africa

    PubMed Central

    2014-01-01

    Background The National Malaria Control Program (NMCP) has been using pirimiphos methyl for the first time for indoor residual spraying (IRS) in Benin. The first round was a success with a significant decrease of entomological indicators of malaria transmission in the treated districts. We present the results of the entomological impact on malaria transmission. Entomologic parameters in the control area were compared with those in intervention sites. Methods Mosquito collections were carried out in three districts in the Atacora-Dongo region of which two were treated with pirimiphos methyl (Actellic 50EC) (Tanguiéta and Kouandé) and the untreated (Copargo) served as control. Anopheles gambiae s.l. populations were sampled monthly by human landing catch. In addition, window exit traps and pyrethrum spray catches were performed to assess exophagic behavior of Anopheles vectors. In the three districts, mosquito collections were organized to follow the impact of pirimiphos methyl IRS on malaria transmission and possible changes in the behavior of mosquitoes. The residual activity of pirimiphos methyl in the treated walls was also assessed using WHO bioassay test. Results A significant reduction (94.25%) in human biting rate was recorded in treated districts where an inhabitant received less than 1 bite of An. gambiae per night. During this same time, the entomological inoculation rate (EIR) dramatically declined in the treated area (99.24% reduction). We also noted a significant reduction in longevity of the vectors and an increase in exophily induced by pirimiphos methyl on An. gambiae. However, no significant impact was found on the blood feeding rate. Otherwise, the low residual activity of Actellic 50 EC, which is three months, is a disadvantage. Conclusion Pirimiphos methyl was found to be effective for IRS in Benin. However, because of the low persistence of Actellic 50EC used in this study on the treated walls, the recourse to another more residual formulation

  3. High temperature Ir segregation in Ir-B ceramics: Effect of oxygen presence on stability of IrB2 and other Ir-B phases

    SciTech Connect

    Xie, Zhilin; Terracciano, Anthony C.; Cullen, David A.; Blair, Richard G.; Orlovskaya, Nina

    2015-05-13

    The formation of IrB2, IrB1.35, IrB1.1 and IrB monoboride phases in the Ir–B ceramic nanopowder was confirmed during mechanochemical reaction between metallic Ir and elemental B powders. The Ir–B phases were analysed after 90 h of high energy ball milling and after annealing of the powder for 72 h at 1050°C in vacuo. The iridium monoboride (IrB) orthorhombic phase was synthesised experimentally for the first time and identified by powder X-ray diffraction. Additionally, the ReB2 type IrB2 hexagonal phase was also produced for the first time and identified by high resolution transmission electron microscope. Ir segregation along disordered domains of the boron lattice was found to occur during high temperature annealing. Furthermore, these nanodomains may have useful catalytic properties.

  4. Computation of relative dose distribution and effective transmission around a shielded vaginal cylinder with {sup 192}Ir HDR source using MCNP4B

    SciTech Connect

    Sureka, Chandra Sekaran; Aruna, Prakasarao; Ganesan, Singaravelu; Sunny, Chirayath Sunil; Subbaiah, Kamatam Venkata

    2006-06-15

    The present work is primarily focused on the estimation of relative dose distribution and effective transmission around a shielded vaginal cylinder with an {sup 192}Ir source using the Monte Carlo technique. The MCNP4B code was used to evaluate the dose distribution around a tungsten shielded vaginal cylinder as a function of thickness and angular shielding. The dose distribution and effective transmission of {sup 192}Ir by 0.8 cm thickness tungsten were also compared with that for gold and lead. Dose distributions were evaluated for different distances starting from 1.35 cm to 10.15 cm from the center of the cylinder. Dose distributions were also evaluated sequentially from 0 deg.to 180 deg.for every 5 deg.interval. Studies show that all the shielding material at 0.8 cm thickness contribute tolerable doses to normal tissues and also protect the critical organs such as the rectum and bladder. However, the computed dose values are in good agreement with the reported experimental values. It was also inferred that the higher the shielding angles, the more the protection of the surrounding tissues. Among the three shielding materials, gold has been observed to have the highest attenuation and hence contribute lowest transmission in the shielded region. Depending upon the shielding angle and thickness, it is possible to predict the dose distribution using the MCNP4B code. In order to deliver the higher dose to the unshielded region, lead may be considered as the shielding material and further it is highly economic over other materials.

  5. Nanosecond Time Resolved Electron Diffraction Studies of the (Alpha) to (Beta) Transition in Pure Ti Thin Films using the Dynamic Transmission Electron Microscope (DTEM)

    SciTech Connect

    LaGrange, T; Campbell, G H; Colvin, J D; Reed, B; King, W E

    2005-12-09

    The transient events of the {alpha}-{beta} martensitic transformation in nanocrystalline Ti films were explored via single shot electron diffraction patterns with 1.5 ns temporal resolution. The diffraction patterns were acquired with a newly constructed dynamic transmission electron microscope (DTEM), which combines nanosecond pulsed laser systems and pump-probe techniques with a conventional TEM. With the DTEM, the transient events of fundamental material processes, that are far too fast to be studied by conventional bulk techniques, can be captured in the form of electron diffraction patterns or images with nanosecond temporal resolution. The transient phenomena of the martensitic transformations in nanocrystalline Ti is ideally suited for study in the DTEM, with their rapid nucleation, characteristic interface velocities {approx}1 km/s, and significant irreversible microstructural changes. Free-standing 40-nm-thick Ti films were laser-heated at a rate of {approx}10{sup 10} K/s to a temperature above the 1155 K transition point, then probed at various time intervals with a 1.5-ns-long, intense electron pulse. Diffraction patterns show an almost complete transition to the {beta} phase within 500 ns. Postmortem analysis (after the sample is allowed to cool) shows a reversion to the {alpha} phase coupled with substantial grain growth, lath formation, and texture modification. The cooled material also shows a complete lack of apparent dislocations, suggesting the possible importance of a ''massive'' short-range diffusion transformation mechanism.

  6. LO-TO splittings, effective charges and interactions in electro-optic meta-nitroaniline crystal as studied by polarized IR reflection and transmission spectra

    NASA Astrophysics Data System (ADS)

    Szostak, M. M.; Le Calvé, N.; Romain, F.; Pasquier, B.

    1994-10-01

    The polarized IR reflection spectra of the meta-nitroaniline ( m-NA) single crystal along the a, b and c crystallographic axes as well as the b and c polarized transmission spectra have been measured in the 100-400 cm -1 region. The LO-TO splitting values have been calculated from the reflection spectra by fitting them with the four parameter dielectric function. The dipole moment derivatives, relevant to dynamic effective charges, of the vibrations have also been calculated and used to check the applicability of the oriented gas model (OGM) to reflection spectra. The discrepancies from the OGM have been discussed in terms of vibronic couplings, weak hydrogen bondings (HB) and intramolecular charge transfer.

  7. Multilayer graphene stacks grown by different methods-thickness measurements by X-ray diffraction, Raman spectroscopy and optical transmission

    SciTech Connect

    Tokarczyk, M. Kowalski, G.; Kępa, H.; Grodecki, K.; Drabińska, A.; Strupiński, W.

    2013-12-15

    X-ray diffraction, Raman spectroscopy and Optical absorption estimates of the thickness of graphene multi layer stacks (number of graphene layers) are presented for three different growth techniques. The objective of this work was focused on comparison and reconciliation of the two already widely used methods for thickness estimates (Raman and Absorption) with the calibration of the X-ray method as far as Scherer constant K is concerned and X-ray based Wagner-Aqua extrapolation method.

  8. Two-way multi-band optical/IR transmission measurements in the Persian Gulf coastal region

    NASA Astrophysics Data System (ADS)

    de Jong, Arie N.; Fritz, Peter J.

    2005-10-01

    The atmospheric conditions in the Persian Gulf region are significantly different from other places in the world. The particle size distribution may vary daily and during the day. The aerosols can contribute to the amount of rainfall over land, important for the nations around the Gulf. In 2004 NASNGSFC and NRL (Naval Research Laboratory) introduced a proposal to improve the modelling of aerosol transport for the Persian Gulf area. The proposal included a measurement campaign in the UAE (United Arabian Emirates), held in the summer/fall of 2004, sponsored by the DWRS (Department of Water Resources Studies) in Abu Dhabi: UAEz (Unified Aerosol Experiment in the UAE). In this campaign NASA installed a number of multi-spectral sun-photometers at various locations in the UAE (http://aeronet.gsfc.nasa.gov). NRL installed ground based and airborne particle samplers. In addition, TNO (the Netherlands) installed its multi-band opticaUIR transmissometer, in order to collect horizontal, path-integrated transmission data. This device provides additional information on the scattering behaviour of the aerosols compared to the other instruments, which either integrate scattering over the full vertical path (the NASA sun-photometers, providing the Aerosol Optical Depth (AOD)) or sample the particles in-situ (the NRL particle samplers, providing size distribution and composition). This paper deals with our transmission measurement set-up, which was located in a coastal area near Abu Dhabi. This location allowed the investigation of the local variability of the atmospheric conditions: from desert dust to pollution, such as fossil fuel and biomass burning, depending on the wind direction. For logistic reasons a set-up was chosen with a retro-reflector. This choice implies consequences for the calibration procedure and measurement accuracy, which are discussed in detail. Also the effects of path-inhomogeneity and scintillation for such a two-way set-up are considered. Results are

  9. HfO2/SiO2 multilayer based reflective and transmissive optics from the IR to the UV

    NASA Astrophysics Data System (ADS)

    Wang, Jue; Hart, Gary A.; Oudard, Jean Francois; Wamboldt, Leonard; Roy, Brian P.

    2016-05-01

    HfO2/SiO2 multilayer based reflective optics enable threat detection in the short-wave/middle-wave infrared and high power laser targeting capability in the near infrared. On the other hand, HfO2/SiO2 multilayer based transmissive optics empower early missile warning by taking advantage of the extremely low noise light detection in the deep-ultraviolet region where solar irradiation is strongly absorbed by the ozone layer of the earth's atmosphere. The former requires high laser damage resistance, whereas the latter needs a solar-blind property, i.e., high transmission of the radiation below 290 nm and strong suppression of the solar background from 300 nm above. The technical challenges in both cases are revealed. The spectral limits associated with the HfO2 and SiO2 films are discussed and design concepts are schematically illustrated. Spectral performances are realized for potential A and D and commercial applications.

  10. Third-dimension information retrieval from a single convergent-beam transmission electron diffraction pattern using an artificial neural network

    NASA Astrophysics Data System (ADS)

    Pennington, Robert S.; Van den Broek, Wouter; Koch, Christoph T.

    2014-05-01

    We have reconstructed third-dimension specimen information from convergent-beam electron diffraction (CBED) patterns simulated using the stacked-Bloch-wave method. By reformulating the stacked-Bloch-wave formalism as an artificial neural network and optimizing with resilient back propagation, we demonstrate specimen orientation reconstructions with depth resolutions down to 5 nm. To show our algorithm's ability to analyze realistic data, we also discuss and demonstrate our algorithm reconstructing from noisy data and using a limited number of CBED disks. Applicability of this reconstruction algorithm to other specimen parameters is discussed.

  11. Influence of deposition conditions on Ir/IrO2 oxygen barrier effectiveness

    NASA Astrophysics Data System (ADS)

    Pinnow, C. U.; Kasko, I.; Nagel, N.; Poppa, S.; Mikolajick, T.; Dehm, C.; Hosler, W.; Bleyl, F.; Jahnel, F.; Seibt, M.; Geyer, U.

    2002-06-01

    The influence of the deposition temperature during the reactive sputtering process on the microstructure of thin Ir and IrO2 films deposited on oxidized Si substrates was investigated and related to the oxygen barrier effectiveness. For this purpose differential thermal analysis combined with residual gas analysis by mass spectrometry was used for the investigation of the microstructural and chemical behavior of the as-sputtered IrO2 films upon heating. Moreover, in situ stress relaxation analyses up to 900 degC, in and ex situ x-ray diffraction measurements were done for various annealing conditions. The investigated polycrystalline IrO2 films exhibited a large compressive stress and a distorted lattice due to the sputter deposition process. It is demonstrated that a high deposition temperature involves a delayed relaxation of the IrO2 grains which is causing an extrinsic, enhanced defect controlled oxygen mobility for the annealing temperatures below the recrystallization. The well-known low intrinsic oxygen diffusivity was only found in those samples which show--in addition to the recovery process--a recrystallization at low temperatures and thus a formation and growth of a new generation of grains with a lattice spacing as in bulk IrO2. Moreover, the oxygen diffusion in Ir films was investigated and the oxygen was found to penetrate the Ir films very quickly at elevated temperatures. The microstructure of the films was investigated by cross sectional transmission electron microscopy and it is shown that the cold-sputtered columnar IrO2 films protect the underlying layers from oxidation during a 700 degC high temperature oxygen anneal with an optimized Ir/IrO2 oxygen barrier stack.

  12. A collimated focused ultrasound beam of high acoustic transmission and minimum diffraction achieved by using a lens with subwavelength structures

    SciTech Connect

    Lin, Zhou; Tu, Juan; Cheng, Jianchun; Guo, Xiasheng E-mail: dzhang@nju.edu.cn; Wu, Junru; Huang, Pingtong; Zhang, Dong E-mail: dzhang@nju.edu.cn

    2015-09-14

    An acoustic focusing lens incorporated with periodically aligned subwavelength grooves corrugated on its spherical surface has been developed. It is demonstrated theoretically and experimentally that acoustic focusing achieved by using the lens can suppress the relative side-lobe amplitudes, enhance the focal gain, and minimize the shifting of the focus. Use of the lens coupled with a planar ultrasound transducer can generate an ultrasound beam with enhanced acoustic transmission and collimation effect, which offers the capability of improving the safety, efficiency, and accuracy of targeted surgery implemented by high intensity focused ultrasound.

  13. Comparative investigation of Fourier Transform Infrared (FT-IR) spectroscopy and X-ray Diffraction (XRD) in the determination of cotton fiber crystallinity

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Despite considerable efforts in developing the curve-fitting protocol to evaluate the crystallinity index (CI) from the X-ray diffraction (XRD) measurement, in its present state XRD procedure can only provide a qualitative or semi-quantitative assessment of the amounts of crystalline or amorphous po...

  14. Detailed structural analysis of epitaxial MBE-grown Fe/Cr superlattices by x-ray diffraction and transmission-electron spectroscopy

    SciTech Connect

    Gomez, M.E.; Santamaria, J.; Kim, S.; Schuller, Ivan K.; Krishnan, Kannan M.

    2005-03-15

    We have performed a detailed quantitative structural analysis of epitaxial [Fe(3 nm)/Cr(1.2 nm)]{sub 20} superlattices by low- and high-angle x-ray diffraction, and energy-filtered transmission electron microscopy on cross-section samples. The interface roughness was changed systematically by varying the substrate temperature (150-250 deg. C) maintaining all other growth parameters fixed. Direct imaging of the interfaces allows examining the roughness of the individual interfaces and its evolution with thickness. A statistical analysis of the local interface width for the individual layers supplies the roughness static and dynamic exponents. High-temperature samples (250 deg. C) show roughness decreasing with thickness as a result of surface-diffusion-dominated growth. Low-temperature samples (150 deg. C) show anomalous non-self-affine roughness characterized by a time-dependent local interface width.

  15. Stable Ir/SiO2 catalyst for selective hydrogenation of crotonaldehyde

    NASA Astrophysics Data System (ADS)

    Hong, Xiao; Li, Bo; Wang, Yuejuan; Lu, Jiqing; Hu, Gengshen; Luo, Mengfei

    2013-04-01

    Vapor-phase selective hydrogenation of crotonaldehyde was conducted over Ir/SiO2 catalysts to investigate the effects of Ir loading on the catalytic behaviors. The catalysts were characterized by X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), CO chemisorption, temperature-programmed reduction (TPR), diffuse reflectance infrared Fourier transform spectra of CO adsorption (CO-DRIFTS), NH3 temperature-programmed desorption (NH3-TPD), and temperature-programmed oxidation (TPO). It was found that the particle size of Ir in the catalyst increased with Ir loading, being 2.1, 3.9 and 6.7 nm for the 1Ir/SiO2, 3Ir/SiO2 and 5Ir/SiO2 catalyst, respectively. The Ir species on the Ir/SiO2 catalysts consisted of Ir0 and Irδ+, but the average valence of Ir species decreased with increasing Ir loading. Also, catalytic testing results revealed that the reactivity of the catalyst increased with Ir loading. Interestingly, it was found that the reaction underwent an induction period, with the conversion of crotonaldehyede and the selectivity to crotyl alcohol gradually increasing during the reaction, and eventually reaching a steady state. The highest selectivity (77.6%) to crotyl alcohol was obtained over the 3Ir/SiO2 catalyst, and the conversion increased gradually to 15.6%. The catalytic behavior of these stable catalysts could be attributed to the proper Ir particle size, the existence of Ir0 and Irδ+ species on the surface, and high amount of surface acid sites in these catalysts.

  16. Anharmonic Computations Meet Experiments (IR, Raman, Neutron Diffraction) for Explaining the Behavior of 1,3,5-Tribromo-2,4,6-trimethylbenzene.

    PubMed

    Meinnel, Jean; Latouche, Camille; Ghanemi, Soumia; Boucekkine, Abdou; Barone, Vincenzo; Moréac, Alain; Boudjada, Ali

    2016-02-25

    In the present paper we first show the experimental Raman, infrared, and neutron INS spectra of tribromomesitylene (TBM) measured in the range 50-3200 cm(-1) using crystalline powders at 6 or 4 K. Then, the bond lengths and angles determined by neutron diffraction using a TBM single crystal at 14 K are compared to the computed ones at different levels of theory. Anharmonic computations were then performed on the relaxed structure using the VPT2 approach, and for the lowest normal modes, the HRAO model has led to a remarkable agreement for the assignment of the experimental signatures. A particularity appears for frequencies below 150 cm(-1), and in particular for those concerning the energy levels of "hindered rotation" of the three methyl groups, they must be calculated for one-dimensional symmetrical tops independent of the frame vibrations. This fact is consistent with the structure established by neutron diffraction: the protons of the methyl groups undergoing huge "libration" motions are widely spread in space. The values of the transitions between the librational levels determined by inelastic neutron scattering indicate that the hindering potentials are mainly due to intermolecular interactions different for each methyl group in the triclinic cell. PMID:26836589

  17. EC-QCL mid-IR transmission spectroscopy for monitoring dynamic changes of protein secondary structure in aqueous solution on the example of β-aggregation in alcohol-denaturated α-chymotrypsin.

    PubMed

    Alcaráz, Mirta R; Schwaighofer, Andreas; Goicoechea, Héctor; Lendl, Bernhard

    2016-06-01

    In this work, a novel EC-QCL-based setup for mid-IR transmission measurements in the amide I region is introduced for monitoring dynamic changes in secondary structure of proteins. For this purpose, α-chymotrypsin (aCT) acts as a model protein, which gradually forms intermolecular β-sheet aggregates after adopting a non-native α-helical structure induced by exposure to 50 % TFE. In order to showcase the versatility of the presented setup, the effects of varying pH values and protein concentration on the rate of β-aggregation were studied. The influence of the pH value on the initial reaction rate was studied in the range of pH 5.8-8.2. Results indicate an increased aggregation rate at elevated pH values. Furthermore, the widely accessible concentration range of the laser-based IR transmission setup was utilized to investigate β-aggregation across a concentration range of 5-60 mg mL(-1). For concentrations lower than 20 mg mL(-1), the aggregation rate appears to be independent of concentration. At higher values, the reaction rate increases linearly with protein concentration. Extended MCR-ALS was employed to obtain pure spectral and concentration profiles of the temporal transition between α-helices and intermolecular β-sheets. Comparison of the global solutions obtained by the modelled data with results acquired by the laser-based IR transmission setup at different conditions shows excellent agreement. This demonstrates the potential and versatility of the EC-QCL-based IR transmission setup to monitor dynamic changes of protein secondary structure in aqueous solution at varying conditions and across a wide concentration range. Graphical abstract EC-QCL IR spectroscopy for monitoring protein conformation change. PMID:27007739

  18. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    PubMed Central

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-01-01

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. The epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystalline Ir nanocrystals. PMID:26923862

  19. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    DOE PAGESBeta

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-02-29

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. As a result, the epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystallinemore » Ir nanocrystals.« less

  20. Epitaxial growth of iridate pyrochlore Nd2Ir2O7 films

    NASA Astrophysics Data System (ADS)

    Gallagher, J. C.; Esser, B. D.; Morrow, R.; Dunsiger, S. R.; Williams, R. E. A.; Woodward, P. M.; McComb, D. W.; Yang, F. Y.

    2016-02-01

    Epitaxial films of the pyrochlore Nd2Ir2O7 have been grown on (111)-oriented yttria-stabilized zirconia (YSZ) substrates by off-axis sputtering followed by post-growth annealing. X-ray diffraction (XRD) results demonstrate phase-pure epitaxial growth of the pyrochlore films on YSZ. Scanning transmission electron microscopy (STEM) investigation of an Nd2Ir2O7 film with a short post-annealing provides insight into the mechanism for crystallization of Nd2Ir2O7 during the post-annealing process. STEM images reveal clear pyrochlore ordering of Nd and Ir in the films. The epitaxial relationship between the YSZ and Nd2Ir2O7 is observed clearly while some interfacial regions show a thin region with polycrystalline Ir nanocrystals.

  1. Lattice vibration spectra. Part LXXXII. Brucite-type hydroxides M(OH)2 (M = Ca, Mn, Co, Fe, Cd) — IR and Raman spectra, neutron diffraction of Fe(OH)2

    NASA Astrophysics Data System (ADS)

    Lutz, H. D.; Möller, H.; Schmidt, M.

    1994-12-01

    Fe3+-free white rust Fe(O(H,D))2 has been prepared and characterized by X-ray, neutron diffraction, and IR and Raman spectroscopic methods. The crystal structure of Fe(OH)2 (space group Poverline3ml, Z = 1, a = 326.289(1) pm and c = 460.4(1)pm; V = 42.45(1) × 106 pm3) was refined to a final RI = 5.6%. The results of IR and Raman spectra of the brucite-type M(O(H,D))2 (M = Ca, Mn, Fe, Co, Cd) are presented and discussed in terms of (i) assignment of the librational and translational modes, (ii) frequency shifts with respect to MO bond lengths, unit-cell volumes and masses of the atoms involved, and (iii) the nature of the large unit-cell group splittings of the OH stretching modes. Due to different bonding, i.e. more or less covalent, the brucite-type hydroxides can be divided into two groups of M = Ca, Mg, and M = Fe, Co, Ni, and Cd, respectively.

  2. In search of the elusive IrB2: Can mechanochemistry help?

    NASA Astrophysics Data System (ADS)

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A.; Lapidus, Saul H.; Kata, Dariusz; Rutkowski, Paweł; Lis, Jerzy

    2016-01-01

    The previously unknown hexagonal ReB2-type IrB2 diboride and orthorhombic IrB monoboride phases were produced by mechanochemical syntheses. High energy ball milling of elemental Ir and B powder for 30 h, followed by annealing of the powder at 1050 °C for 48 h, resulted in the formation of the desired phases. Both traditional laboratory and high resolution synchrotron X-ray diffraction (XRD) analyses were used for phase identification of the synthesized powder. In addition to XRD, scanning electron microscopy and transmission electron microscopy were employed to further characterize the microstructure of the phases produced.

  3. In search of the elusive IrB2: Can mechanochemistry help?

    DOE PAGESBeta

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A.; Lapidus, Saul H.; Kata, Dariusz; Rutkowski, Paweł; Lis, Jerzy

    2015-10-20

    We produced hexagonal ReB2-type IrB2 diboride and orthorhombic IrB monoboride phases, that were previously unknown and saw them produced by mechanochemical syntheses. High energy ball milling of elemental Ir and B powder for 30 h, followed by annealing of the powder at 1050 °C for 48 h, resulted in the formation of the desired phases. Both traditional laboratory and high resolution synchrotron X-ray diffraction (XRD) analyses were used for phase identification of the synthesized powder. Additionally, scanning electron microscopy and transmission electron microscopy were employed, along with XRD, to further characterize the microstructure of the phases produced.

  4. Synthesis, crystal structure analysis, spectral IR, NMR UV-Vis investigations, NBO and NLO of 2-benzoyl-N-(4-chlorophenyl)-3-oxo-3-phenylpropanamide with use of X-ray diffractions studies along with DFT calculations

    NASA Astrophysics Data System (ADS)

    Demir, Sibel; Sarioğlu, Ahmet Oral; Güler, Semih; Dege, Necmi; Sönmez, Mehmet

    2016-08-01

    The title compound, 2-benzoyl-N-(4-chlorophenyl)-3-oxo-3-phenylpropanamide compound (C22H16NO3Cl) has been synthesized and characterized by X-ray diffraction, IR, 1H and 13C NMR and UV-Vis spectra. Optimized geometrical structure, harmonic vibrational frequencies and chemical shifts were computed using hybrid-DFT (B3LYP and B3PW91) methods and 6-311G(d,p) as the basis set. The results of the optimized molecular structure are presented and compared with the experimental X-ray diffraction. The calculated optimized geometries, vibrational frequencies and 1H NMR chemical shift values are in strong agreement with experimentally measured values. UV-Vis spectrum of the title compound, was also recorded and the electronic properties, such as calculated energies, excitation energies, oscillator strengths, dipole moments and frontier orbital energies and band gap energies were computed with TDDFT-B3LYP methodolgy and using 6-311G(d,p) as the basis set. Furthermore, frontier molecular orbitals (FMO), molecular electrostatic potential (MEP), natural bond orbital (NBO) and non linear optical (NLO) properties were performed by using B3LYP/6-311G(d,p) level for the title compound.

  5. Definitive support by transmission electron microscopy, electron diffraction, and electron density maps for the formation of a BCC lattice from poly[N-[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]ethyleneimine].

    PubMed

    Duan, H; Hudson, S D; Ungar, G; Holerca, M N; Percec, V

    2001-10-01

    Transmission electron microscopy (TEM), electron diffraction (ED), and electron density maps (EDM) experiments were carried out on a poly[N-[3,4,5-tris(n-dodecan-1-yloxy)benzoyl]ethyleneimine] [poly[(3,4,5)12G1-Oxz

  6. Structure refinement of the δ1p phase in the Fe–Zn system by single-crystal X-ray diffraction combined with scanning transmission electron microscopy

    PubMed Central

    Okamoto, Norihiko L.; Tanaka, Katsushi; Yasuhara, Akira; Inui, Haruyuki

    2014-01-01

    The structure of the δ1p phase in the iron−zinc system has been refined by single-crystal synchrotron X-ray diffraction combined with scanning transmission electron microscopy. The large hexagonal unit cell of the δ1p phase with the space group of P63/mmc comprises more or less regular (normal) Zn12 icosahedra, disordered Zn12 icosahedra, Zn16 icosioctahedra and dangling Zn atoms that do not constitute any polyhedra. The unit cell contains 52 Fe and 504 Zn atoms so that the compound is expressed with the chemical formula of Fe13Zn126. All Fe atoms exclusively occupy the centre of normal and disordered icosahedra. Iron-centred normal icosahedra are linked to one another by face- and vertex-sharing forming two types of basal slabs, which are bridged with each other by face-sharing with icosioctahedra, whereas disordered icosahedra with positional disorder at their vertex sites are isolated from other polyhedra. The bonding features in the δ1p phase are discussed in comparison with those in the Γ and ζ phases in the iron−zinc system. PMID:24675597

  7. Transmission Mössbauer spectroscopy and x-ray diffraction studies on the structure of nanocrystalline Fe-Cu-Si-B alloys

    NASA Astrophysics Data System (ADS)

    Liu, X. D.; Lu, K.; Hu, Z. Q.; Ding, B. Z.; Zhu, J.; Jiang, J.

    1994-04-01

    Nanocrystalline Fe-Cu-Si-B alloys with grain sizes of 25-90 nm were synthesized by crystallization of the amorphous alloy. Two nanocrystalline phases of α-Fe(Si) and Fe2B were observed in all tested samples. Transmission Mössbauer spectroscopy investigation on the structure of nanocrystalline Fe-Cu-Si-B alloys showed that Si atoms are completely and substitutionally dissolved in Fe bcc lattice and the arrangement of the Si atoms in the α-Fe(Si) phase shows short range order (SRO), whereas 8.5-9.7 at. % of the B atoms were found as Fe2B and the remainder were located in the interfaces. When grains grow larger, the arrangement of the Si atoms in the α-Fe(Si) phase changes. Interestingly, x-ray diffraction results reveal that the lattice constant of α-Fe(Si) phase decreases rapidly with grain coarsening. Based on the thermodynamic analysis, the changes in the lattice constant of the α-Fe(Si) phase and SRO of Si atoms in bcc Fe lattices were attributed to the lattice expansion as a result of the variation of vacancy concentration in α-Fe(Si) solid solution. Meanwhile, owing to the interface contribution, the alloy with small grain size is found to exhibit large values of half linewidth (HLW) and isomer shift (IS) in the Mössbauer spectra. The results from electrical resistivity measurements agree and confirm the strong effects of the lattice distortion and interfaces.

  8. Using multiple diffractive optical elements in infrared lens design

    NASA Astrophysics Data System (ADS)

    Sinclair, R. Lawrence; High, Martin; Strnad, Vladimir

    1999-07-01

    Many IR lenses include Diffractive Optical Elements (DOEs) which have been incorporated to reduce the lens complexity and/or the tolerance sensitivity. In many cases the diffractive surface includes an asphere to achieve further aberration correction. For complex lens systems such as IR multi-FOV and IR zoom lenses there is a strong motivation to use multiple diffractive optical elements. This paper reviews the performance impact and productivity advantages of using multiple diffractive optical elements in an IR lens.

  9. Preparation and reactivity of the heterobimetallic ReIr face-shared bioctahedral compounds Cp*Ir(mu-Cl)(3)Re(CO)(3) and Cp*Ir(mu-SC6H4Me-4)(3)Re(CO)(3): X-ray diffraction structures and redox behavior

    SciTech Connect

    Wang, Xiaoping; Hammons, Casey; Richmond, Michael G.

    2009-01-01

    Thermolysis of the dinuclear compound [Cp*IrCl2](2) (1) with ClRe(CO)(5) (2) leads to the formation of the confacial bioctahedral compound Cp*Ir(mu-Cl)(3)Re(CO)(3) (3) in high yield. Whereas the substitution of the chloride ligands in 3 is observed on treatment with excess p-methylbenzenethiol to furnish the sulfido-bridged compound Cp*Ir(mu-SC6H4Me-4)(3)Re(CO)(3) (4), 3 undergoes fragmentation upon reaction with tertiary phosphines [PPh3 and P(OMe)(3)] to furnish the mononuclear compounds CP*IrCl2P and fac-ClRe-(CO3)P-2. Both 3 and 4 have been isolated and fully characterized in solution by IR and H-1 NMR spectroscopies, and their solid-state structures have been established by X-ray crystallography. The redox properties of 3 and 4 have been explored by cyclic voltammetry, and the results are discussed relative to extended Huckel MO calculations.

  10. IR fiber sources for scene projection

    NASA Astrophysics Data System (ADS)

    Shaw, L. B.; Sanghera, J. S.; Aggarwal, I. D.

    2007-04-01

    Naval Research Laboratory has developed IR transmitting fiber and IR fiber sources which can be used for HWIL testing. IR transmitting fiber is capable of broad transmission from near IR to LWIR and can be formed into bundles for imaging. IR fiber sources are based on rare earth doped glass or nonlinear processes in the glass and are cable of high brightness IR emission. Recently, NRL developed a four emitter MWIR fiber source which is capable of high temperature simulation, high dynamic range, and fast response. New broadband fiber sources based upon IR supercontinuum generation in IR fibers are also being developed. In this paper, we will report on these technologies.

  11. Preparation of IrO2 nanoparticles with SBA-15 template and its supported Pt nanocomposite as bifunctional oxygen catalyst

    NASA Astrophysics Data System (ADS)

    Kong, Fan-Dong; Liu, Jing; Ling, Ai-Xia; Xu, Zhi-Qiang; Wang, Hui-Yun; Kong, Qing-Sheng

    2015-12-01

    In the present work, we report the syntheses of IrO2 nanoparticles with SBA-15 template (s-IrO2), and s-IrO2 supported Pt nanocomposite (Pt/s-IrO2) as bifunctional oxygen catalyst. Physical characterizations including X-ray diffraction and transmission electron microscopy demonstrate that s-IrO2 catalyst has excellent uniformity and regularity in particle shape and much ordered distribution in geometric space, and Pt/s-IrO2 catalyst shows a uniform Pt dispersion on the surface of the s-IrO2 particles. Electrochemical analyses prove that s-IrO2 catalyst possesses superior OER activity at operating potentials; and that Pt/s-IrO2 catalyst, in comparison to Pt/commercial IrO2, has higher ESA value and ORR catalytic performance with a mechanism of four-electron pathway and a high ORR efficiency. And as a bifunctional oxygen catalyst, Pt/s-IrO2 also exhibits more remarkable OER performance than the commercial one. The s-IrO2 nanoparticles will be a promising active component (for OER), and suitable for Pt support (for ORR).

  12. Calculating cellulose diffraction patterns

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although powder diffraction of cellulose is a common experiment, the patterns are not widely understood. The theory is mathematical, there are numerous different crystal forms, and the conventions are not standardized. Experience with IR spectroscopy is not directly transferable. An awful error, tha...

  13. Evolution of titania nanotubes-supported WO{sub x} species by in situ thermo-Raman spectroscopy, X-ray diffraction and high resolution transmission electron microscopy

    SciTech Connect

    Cortes-Jacome, M.A.; Angeles-Chavez, C.; Morales, M.; Lopez-Salinas, E.; Toledo-Antonio, J.A.

    2007-10-15

    Structural evolution of WO{sub x} species on the surface of titania nanotubes was followed by in situ thermo-Raman spectroscopy. A total of 15 wt% of W atoms were loaded on the surface of a hydroxylated titania nanotubes by impregnation with ammonium metatungstate solution and then, the sample was thermally treated in a Linkam cell at different temperatures in nitrogen flow. The band characteristic of the W=O bond was observed at 962 cm{sup -1} in the dried sample, which vanished between 300 and 700 deg. C, and reappear again after annealing at 800 deg. C, along with a broad band centered at 935 cm{sup -1}, attributed to the v{sub 1} vibration of W=O in tetrahedral coordination. At 900 and 1000 deg. C, the broad band decomposed into four bands at 923, 934, 940 and 950 cm{sup -1}, corresponding to the symmetric and asymmetric vibration of W=O bonds in Na{sub 2}WO{sub 4} and Na{sub 2}W{sub 2}O{sub 7} phases as determined by X-ray diffraction and High resolution transmission electron microscopy (HRTEM). The structure of the nanotubular support was kept at temperatures below 450 deg. C, thereafter, it transformed into anatase being stabilized at temperatures as high as 900 deg. C. At 1000 deg. C, anatase phase partially converted into rutile. After annealing at 1000 deg. C, a core-shell model material was obtained, with a shell of ca. 5 nm thickness, composed of sodium tungstate nanoclusters, and a core composed mainly of rutile TiO{sub 2} phase. - Graphical abstract: Titania nanotubes loaded with 15 wt% W atoms were characterized from room temperature (rt) to 1000 deg. C by thermo-Raman spectroscopy in N{sub 2}. At 1000 deg. C, a core-shell model material was obtained, with a shell thickness of ca. 5 nm composed by nanoclusters of sodium tungstate, and a core composed mainly of rutile TiO{sub 2} phase.

  14. A pseudo-tetragonal tungsten bronze superstructure: a combined solution of the crystal structure of K6.4(Nb,Ta)(36.3)O94 with advanced transmission electron microscopy and neutron diffraction.

    PubMed

    Paria Sena, Robert; Babaryk, Artem A; Khainakov, Sergiy; Garcia-Granda, Santiago; Slobodyanik, Nikolay S; Van Tendeloo, Gustaaf; Abakumov, Artem M; Hadermann, Joke

    2016-01-21

    The crystal structure of the K6.4Nb28.2Ta8.1O94 pseudo-tetragonal tungsten bronze-type oxide was determined using a combination of X-ray powder diffraction, neutron diffraction and transmission electron microscopy techniques, including electron diffraction, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM), annular bright field STEM (ABF-STEM) and energy-dispersive X-ray compositional mapping (STEM-EDX). The compound crystallizes in the space group Pbam with unit cell parameters a = 37.468(9) Å, b = 12.493(3) Å, c = 3.95333(15) Å. The structure consists of corner sharing (Nb,Ta)O6 octahedra forming trigonal, tetragonal and pentagonal tunnels. All tetragonal tunnels are occupied by K(+) ions, while 1/3 of the pentagonal tunnels are preferentially occupied by Nb(5+)/Ta(5+) and 2/3 are occupied by K(+) in a regular pattern. A fractional substitution of K(+) in the pentagonal tunnels by Nb(5+)/Ta(5+) is suggested by the analysis of the HAADF-STEM images. In contrast to similar structures, such as K2Nb8O21, also parts of the trigonal tunnels are fractionally occupied by K(+) cations. PMID:26646168

  15. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, Michael D.; Britten, Jerald A.; Nguyen, Hoang T.; Boyd, Robert; Shore, Bruce W.

    1999-01-01

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described.

  16. Multilayer dielectric diffraction gratings

    DOEpatents

    Perry, M.D.; Britten, J.A.; Nguyen, H.T.; Boyd, R.; Shore, B.W.

    1999-05-25

    The design and fabrication of dielectric grating structures with high diffraction efficiency used in reflection or transmission is described. By forming a multilayer structure of alternating index dielectric materials and placing a grating structure on top of the multilayer, a diffraction grating of adjustable efficiency, and variable optical bandwidth can be obtained. Diffraction efficiency into the first order in reflection varying between 1 and 98 percent has been achieved by controlling the design of the multilayer and the depth, shape, and material comprising the grooves of the grating structure. Methods for fabricating these gratings without the use of ion etching techniques are described. 7 figs.

  17. Preparation of Pt/Irx(IrO2)10 - x bifunctional oxygen catalyst for unitized regenerative fuel cell

    NASA Astrophysics Data System (ADS)

    Kong, Fan-Dong; Zhang, Sheng; Yin, Ge-Ping; Zhang, Na; Wang, Zhen-Bo; Du, Chun-Yu

    2012-07-01

    Bifunctional Pt/Irx(IrO2)10 - x (x < 10) catalyst for unitized regenerative fuel cell (URFC) has been prepared by depositing Pt on Irx(IrO2)10 - x support which is obtained initially from Adams fusion method. X-ray diffraction and transmission electron microscopy show that ultrafine and narrow distributed Pt/Ir3(IrO2)7 nanocomposites are formed. Electrochemical measurements demonstrate that among the series of catalysts studied, Pt/Ir3(IrO2)7 catalyst possesses the highest electrochemical surface area (24.74 m2 g-1) and the highest activity towards oxygen reduction reaction (ORR) (21.71 mA mg-1 at 0.85 V). Meanwhile, considerably high activity towards oxygen evolution reaction (OER) (42.35 mA mg-1 at 1.55 V) is also observed for Pt/Ir3(IrO2)7 catalyst. Kinetic analyses indicate that ORR on Pt/Ir3(IrO2)7 catalyst follows four-electron mechanism. This work opens a new way to fabricate efficient bifunctional oxygen catalyst for URFC.

  18. Phononic crystal diffraction gratings

    NASA Astrophysics Data System (ADS)

    Moiseyenko, Rayisa P.; Herbison, Sarah; Declercq, Nico F.; Laude, Vincent

    2012-02-01

    When a phononic crystal is interrogated by an external source of acoustic waves, there is necessarily a phenomenon of diffraction occurring on the external enclosing surfaces. Indeed, these external surfaces are periodic and the resulting acoustic diffraction grating has a periodicity that depends on the orientation of the phononic crystal. This work presents a combined experimental and theoretical study on the diffraction of bulk ultrasonic waves on the external surfaces of a 2D phononic crystal that consists of a triangular lattice of steel rods in a water matrix. The results of transmission experiments are compared with theoretical band structures obtained with the finite-element method. Angular spectrograms (showing frequency as a function of angle) determined from diffraction experiments are then compared with finite-element simulations of diffraction occurring on the surfaces of the crystal. The experimental results show that the diffraction that occurs on its external surfaces is highly frequency-dependent and has a definite relation with the Bloch modes of the phononic crystal. In particular, a strong influence of the presence of bandgaps and deaf bands on the diffraction efficiency is found. This observation opens perspectives for the design of efficient phononic crystal diffraction gratings.

  19. Diffraction efficiencies of holographic laminar and blazed types gratings for use in a flat-field spectrograph in the 50-200 eV range for transmission electron microscopes

    NASA Astrophysics Data System (ADS)

    Imazono, T.; Koike, M.; Kawachi, T.; Koeda, M.; Nagano, T.; Sasai, H.; Oue, Y.; Yonezawa, Z.; Kuramoto, S.; Sano, K.

    2011-09-01

    A versatile soft x-ray flat-field grating spectrograph to be installed to a conventional transmission electron microscope has been developed. A holographic spherical grating of a 1200-lines/mm effective groove density which places emphasis on the low energy region of 50-200 eV is designed by an aspheric wavefront recording system. Laminar and blazed types master (LM and BM) gratings and their respective replica (LR and BR) gratings are fabricated by holographic exposure and ion-beam etching methods. Absolute diffraction efficiencies in the 50-300 eV range at the angle of incidence of 86.0 degrees were measured using a synchrotron radiation. The first order diffraction efficiencies are 6.1-7.5% (or 12%) for LM (or BM) and 7.4-9.6% (or 13%) for LR (or BR) gratings at near 55 eV, and over 5% (or 8%) in the 50-200 eV range for LM and LR (or BM and BR) gratings. The replica gratings show the comparable first-order diffraction efficiencies with their respective laminar and blazed types of master gratings.

  20. Preparation and characterization of Ir/TiC catalyst for oxygen evolution

    NASA Astrophysics Data System (ADS)

    Ma, Lirong; Sui, Sheng; Zhai, Yuchun

    Nano-sized titanium carbide (TiC) was employed as the support material for an iridium (Ir) electrocatalyst in a proton exchange membrane water electrolyser (PEMWE). The Ir/TiC electrocatalyst for the oxygen evolution reaction (OER) was prepared by chemical reduction and deposition with ultrasonic dispersion. The diameter of the Ir particles deposited on the TiC support is 10-40 nm. The Ir/TiC catalyst has a pore volume of 0.1425 cm 3 g -1, which is about two times as high as that of the corresponding unsupported Ir. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray (EDX) analysis indicate that the Ir particles are nearly uniformly deposited on the surface of the TiC and exhibit remarkably fine variable crystallites and crystal lattice defects, which enhance the density of active sites and greatly improves the catalytic activity of the Ir/TiC catalyst. Cyclic voltammograms (CVs) reveal that the peak current density at 1.5 V versus SCE on the Ir/TiC is about nine times of that for the unsupported Ir black catalyst and potentiostatic analysis shows that the charge passed by the Ir/TiC after 600 s at 1.3 V versus SCE is about 15 times of that for the unsupported Ir catalyst. Electrochemical impedance spectroscopy (EIS) shows that the electrochemical polarization impedance of the Ir/TiC catalyst is about 50 Ω cm 2 per 0.02 mg as compared to 150 Ω cm 2 of the Ir black in the range of high frequency. The diffusion polarization impedances of the Ir/TiC form a semicircle and those of the Ir black are close to a straight line with a phase angle of 45° in the range of low frequency. Thus, the catalytic activity of the Ir/TiC for the OER is significantly higher than that of the unsupported Ir catalyst. The TiC support is chemically and electrochemically stable in the whole range of experimental potentials.

  1. Ionic strength and composition govern the elasticity of biological membranes. A study of model DMPC bilayers by force- and transmission IR spectroscopy.

    PubMed

    Šegota, Suzana; Vojta, Danijela; Pletikapić, Galja; Baranović, Goran

    2015-02-01

    Infrared (IR) spectroscopy was used to quantify the ion mixture effect of seawater (SW), particularly the contribution of Mg(2+) and Ca(2+) as dominant divalent cations, on the thermotropic phase behaviour of 1,2-dimyristoyl-sn-glycero-3-posphocholine (DMPC) bilayers. The changed character of the main transition at 24 °C from sharp to gradual in films and the 1 °C shift of the main transition temperature in dispersions reflect the interactions of lipid headgroups with the ions in SW. Force spectroscopy was used to quantify the nanomechanical hardness of a DMPC supported lipid bilayer (SLB). Considering the electrostatic and ion binding equilibrium contributions while systematically probing the SLB in various salt solutions, we showed that ionic strength had a decisive influence on its nanomechanics. The mechanical hardness of DMPC SLBs in the liquid crystalline phase linearly increases with the increasing fraction of all ion-bound lipids in a series of monovalent salt solutions. It also linearly increases in the gel phase but almost three times faster (the corresponding slopes are 4.9 nN/100 mM and 13.32 nN/100 mM, respectively). We also showed that in the presence of divalent ions (Ca(2+) and Mg(2+)) the bilayer mechanical hardness was unproportionally increased, and that was accompanied with the decrease of Na(+) ion and increase of Cl(-) ion bound lipids. The underlying process is a cooperative and competitive ion binding in both the gel and the liquid crystalline phase. Bilayer hardness thus turned out to be very sensitive to ionic strength as well as to ionic composition of the surrounding medium. In particular, the indicated correlation helped us to emphasize the colligative properties of SW as a naturally occurring complex ion mixture. PMID:25447291

  2. Stoichiometry of alloy nanoparticles from laser ablation of PtIr in acetone and their electrophoretic deposition on PtIr electrodes.

    PubMed

    Jakobi, Jurij; Menéndez-Manjón, Ana; Chakravadhanula, Venkata Sai Kiran; Kienle, Lorenz; Wagener, Philipp; Barcikowski, Stephan

    2011-04-01

    Charged Pt-Ir alloy nanoparticles are generated through femtosecond laser ablation of a Pt₉Ir target in acetone without using chemical precursors or stabilizing agents. Preservation of the target's stoichiometry in the colloidal nanoparticles is confirmed by transmission electron microscopy (TEM)-energy-dispersive x-ray spectroscopy (EDX), high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM)-EDX elemental maps, high resolution TEM and selected area electron diffraction (SAED) measurements. Results are discussed with reference to thermophysical properties and the phase diagram. The nanoparticles show a lognormal size distribution with a mean Feret particle size of 26 nm. The zeta potential of -45 mV indicates high stability of the colloid with a hydrodynamic diameter of 63 nm. The charge of the particles enables electrophoretic deposition of nanoparticles, creating nanoscale roughness on three-dimensional PtIr neural electrodes within a minute. In contrast to coating with Pt or Ir oxides, this method allows modification of the surface roughness without changing the chemical composition of PtIr. PMID:21346297

  3. Effect of temperature on electrical and microstructural changes of coevaporated Ir-Si alloy films

    NASA Astrophysics Data System (ADS)

    Weiss, B. Z.; Tu, K. N.; Smith, D. A.

    1986-01-01

    Electrical and microstructural changes of coevaporated Ir(50)Si(50) have been studied as a function of temperature, from room temperature to 970 C. In situ resistivity measurements, in situ annealing and transmission electron microscopy, Rutherford backscattering spectroscopy, and Seeman-Bohlin glancing angle incidence X-ray diffraction were applied. In the as-deposited state, the alloy film is amorphous and exhibits semiconducting behavior. A two-stage phase transformation occurs in the process of heating. The first transition from amorphous to crystalline IrSi is nucleation-controlled. It is accompanied by an abrupt decrease in resistivity and was found to be dependent on the heating rate and chemical composition. The second crystalline-to-crystalline transformation is controlled by nonstoichiometry of the alloy film. An excess of Ir atoms leads to formation of Ir2Si at about 640 C, while an excess of Si atoms leads to formation of IrSi3 at about 710 C. The second transition is independent of the heating rate. The formation of both Ir2Si and IrSi3 decreases the electrical resistivity. The isothermal transformation from amorphous to crystalline structure follows a sigmoidal function. The apparent activation energy of this process is about 1.32 eV. The kinetic behavior implies random nucleation and interface-controlled two-dimensional growth of the crystalline phase.

  4. IRS organigram

    NASA Technical Reports Server (NTRS)

    Messerschmid, Ernst

    1991-01-01

    Charts and graphs relative to magnetoplasmadynamic (MPD) thruster technology are given. The research activities at the Institute of Space Transportation, University of Stuttgart, are summarized. Information is given on the Institute's Electric Propulsion and Plasma Wind Tunnel; thermal arcjet research; the nozzle-type thruster, DT-IRS; nozzle-type MPD thrusters; a hot anode thruster; the DT6 thruster; the ZT-1 thruster; the cylindrical MPD thruster; and a comparison of continuous and quasi-steady MPD.

  5. Diffractive centrosymmetric 3D-transmission phase gratings positioned at the image plane of optical systems transform lightlike 4D-WORLD as tunable resonators into spectral metrics...

    NASA Astrophysics Data System (ADS)

    Lauinger, Norbert

    1999-08-01

    Diffractive 3D phase gratings of spherical scatterers dense in hexagonal packing geometry represent adaptively tunable 4D-spatiotemporal filters with trichromatic resonance in visible spectrum. They are described in the (lambda) - chromatic and the reciprocal (nu) -aspects by reciprocal geometric translations of the lightlike Pythagoras theorem, and by the direction cosine for double cones. The most elementary resonance condition in the lightlike Pythagoras theorem is given by the transformation of the grating constants gx, gy, gz of the hexagonal 3D grating to (lambda) h1h2h3 equals (lambda) 111 with cos (alpha) equals 0.5. Through normalization of the chromaticity in the von Laue-interferences to (lambda) 111, the (nu) (lambda) equals (lambda) h1h2h3/(lambda) 111-factor of phase velocity becomes the crucial resonance factor, the 'regulating device' of the spatiotemporal interaction between 3D grating and light, space and time. In the reciprocal space equal/unequal weights and times in spectral metrics result at positions of interference maxima defined by hyperbolas and circles. A database becomes built up by optical interference for trichromatic image preprocessing, motion detection in vector space, multiple range data analysis, patchwide multiple correlations in the spatial frequency spectrum, etc.

  6. In search of the elusive IrB2: Can mechanochemistry help?

    SciTech Connect

    Xie, Zhilin; Blair, Richard G.; Orlovskaya, Nina; Cullen, David A.; Lapidus, Saul H.; Kata, Dariusz; Rutkowski, Paweł; Lis, Jerzy

    2015-10-20

    We produced hexagonal ReB2-type IrB2 diboride and orthorhombic IrB monoboride phases, that were previously unknown and saw them produced by mechanochemical syntheses. High energy ball milling of elemental Ir and B powder for 30 h, followed by annealing of the powder at 1050 °C for 48 h, resulted in the formation of the desired phases. Both traditional laboratory and high resolution synchrotron X-ray diffraction (XRD) analyses were used for phase identification of the synthesized powder. Additionally, scanning electron microscopy and transmission electron microscopy were employed, along with XRD, to further characterize the microstructure of the phases produced.

  7. IR Asterisms

    NASA Astrophysics Data System (ADS)

    Riess, Adam

    2010-09-01

    Observing asterisms for photometric calibration provides a "happy medium" between observing single stars which areobservable from the ground but lack statistics, and star clusters which have excellent statistics but are too crowded to observe from the ground.Asterisms in the IR for calibration have been less available than in the optical, e.g., Landolt's standard fields.While ad-hoc asterisms for calibration could be formed from 2MASS calibration, the photometric precision of 2MASSis relatively low, 0.02-0.05, for the fainter stars, m=9-13, that can still be observed without saturation in WFC3-IR.However, IR monitoring of variable phenomena {e.g., AGN SNe, stellar variables} from the ground has produced calibration of stars in asterisms with m=9-13 with a relative uncertainty of 0.001 to 0.01 mag due to the high frequency of monitoring. We have selected 4 such asterisms to observe. Because the stars are bright we need to use subarrays of 64x64 or 128x128 to get read out short enough to avoid saturation. The observations are obtained in pairs of 3 close stars, i.e., 2x3=6 stars per orbit in F125W and F160W as well as a F555W full frame to verify astrometry. In all we expect to measure 24 stars with m=9 to 14. The goal is to provide 2 calibrations, an independent zeropoint and its uncertainty as well as a measure of count rate non linearity. For the latter, an expected CRNL over 2 dex {5 mag} is expected tobe 0.02 mag.

  8. Metastable honeycomb SrTiO3/SrIrO3 heterostructures

    NASA Astrophysics Data System (ADS)

    Anderson, T. J.; Ryu, S.; Zhou, H.; Xie, L.; Podkaminer, J. P.; Ma, Y.; Irwin, J.; Pan, X. Q.; Rzchowski, M. S.; Eom, C. B.

    2016-04-01

    Recent theory predictions of exotic band topologies in (111) honeycomb perovskite SrIrO3 layers sandwiched between SrTiO3 have garnered much attention in the condensed matter physics and materials communities. However, perovskite SrIrO3 film growth in the (111) direction remains unreported, as efforts to synthesize pure SrIrO3 on (111) perovskite substrates have yielded films with monoclinic symmetry rather than the perovskite structure required by theory predictions. In this study, we report the synthesis of ultra-thin metastable perovskite SrIrO3 films capped with SrTiO3 grown on (111) SrTiO3 substrates by pulsed laser deposition. The atomic structure of the ultra-thin films was examined with scanning transmission electron microscopy (STEM), which suggests a perovskite layering distinct from the bulk SrIrO3 monoclinic phase. In-plane 3-fold symmetry for the entire heterostructure was confirmed using synchrotron surface X-ray diffraction to measure symmetry equivalent crystal truncation rods. Our findings demonstrate the ability to stabilize (111) honeycomb perovskite SrIrO3, which provides an experimental avenue to probe the phenomena predicted for this material system.

  9. Growth and characterization of V-shaped IrO(2) nanowedges via metal-organic vapor deposition.

    PubMed

    Chen, C A; Chen, Y M; Huang, Y S; Tsai, D S; Tiong, K K; Du, C H

    2008-11-19

    We report in detail the synthesis and characterization of V-shaped IrO(2) nanowedges (NWs) with an angle of 110° between the two arms. The NWs were grown on top of rutile (R) phase TiO(2) nanorods (NRs) sitting on a sapphire (SA)(100) substrate via metal-organic chemical vapor deposition (MOCVD) by using (C(6)H(7))(C(8)H(12))Ir and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH(3))(2)](4)) as the source reagents. The surface morphology, structural, and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), micro-Raman spectroscopy, transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped IrO(2)(101) NWs on top of R-TiO(2) NRs. The Raman spectrum showed the nanosize induced redshift and peak broadening of the IrO(2) and rutile phase of TiO(2) signatures with respect to that of the bulk counterparts. TEM and SAED characterizations of IrO(2) NCs showed that the nanowedges were crystalline IrO(2) with a twin plane of (101) and twin direction of [Formula: see text] at the V-junction. The probable mechanisms for the formation of well-aligned IrO(2) NWs are discussed. PMID:21836254

  10. Growth and characterization of V-shaped IrO2 nanowedges via metal-organic vapor deposition

    NASA Astrophysics Data System (ADS)

    Chen, C. A.; Chen, Y. M.; Huang, Y. S.; Tsai, D. S.; Tiong, K. K.; Du, C. H.

    2008-11-01

    We report in detail the synthesis and characterization of V-shaped IrO2 nanowedges (NWs) with an angle of 110° between the two arms. The NWs were grown on top of rutile (R) phase TiO2 nanorods (NRs) sitting on a sapphire (SA)(100) substrate via metal-organic chemical vapor deposition (MOCVD) by using (C6H7)(C8H12)Ir and titanium-tetraisopropoxide (TTIP, Ti[OCH(CH3)2]4) as the source reagents. The surface morphology, structural, and spectroscopic properties of the as-deposited nanocrystals (NCs) were characterized by field emission scanning electron microscopy (FESEM), x-ray diffraction (XRD), micro-Raman spectroscopy, transmission electron microscopy (TEM), and selected-area electron diffractometry (SAED). The FESEM images and XRD patterns indicated growth of V-shaped IrO2(101) NWs on top of R-TiO2 NRs. The Raman spectrum showed the nanosize induced redshift and peak broadening of the IrO2 and rutile phase of TiO2 signatures with respect to that of the bulk counterparts. TEM and SAED characterizations of IrO2 NCs showed that the nanowedges were crystalline IrO2 with a twin plane of (101) and twin direction of [\\bar {1} 01] at the V-junction. The probable mechanisms for the formation of well-aligned IrO2 NWs are discussed.

  11. Detonation diffraction through different geometries

    NASA Astrophysics Data System (ADS)

    Sorin, Rémy; Zitoun, Ratiba; Khasainov, Boris; Desbordes, Daniel

    2009-04-01

    We performed the study of the diffraction of a self-sustained detonation from a cylindrical tube (of inner diameter d) through different geometric configurations in order to characterise the transmission processes and to quantify the transmission criteria to the reception chamber. For the diffraction from a tube to the open space the transmission criteria is expressed by d c = k c · λ (with λ the detonation cell size and k c depending on the mixture and on the operture configuration, classically 13 for alkane mixtures with oxygen). The studied geometries are: (a) a sharp increase of diameter ( D/ d > 1) with and without a central obstacle in the diffracting section, (b) a conical divergent with a central obstacle in the diffracting section and (c) an inversed intermediate one end closed tube insuring a double reflection before a final diffraction between the initiator tube and the reception chamber. The results for case A show that the reinitiation process depends on the ratio d/ λ. For ratios below k c the re-ignition takes place at the receptor tube wall and at a fixed distance from the step, i.e. closely after the diffracted shock reflection shows a Mach stem configuration. For ratios below a limit ratio k lim (which depends on D/ d) the re-ignition distance increases with the decrease of d/λ. For both case A and B the introduction of a central obstacle (of blockage ratio BR = 0.5) at the exit of the initiator tube decreases the critical transmission ratio k c by 50%. The results in configuration C show that the re-ignition process depends both on d/ λ and the geometric conditions. Optimal configuration is found that provides the transmission through the two successive reflections (from d = 26 mm to D ch = 200 mm) at as small d/ λ as 2.2 whatever the intermediate diameter D is. This configuration provides a significant improvement in the detonation transmission conditions.

  12. Magnetic ordering in Gd5Ir2Bi and Gd5Ir2Sb

    NASA Astrophysics Data System (ADS)

    Ryan, D. H.; Mas, Nadejda; Rejali, Rasa; Miller, T.; Gerke, Birgit; Heying, Birgit; Pöttgen, Rainer; Flacau, Roxana

    2016-05-01

    155Gd Mössbauer spectroscopy and neutron powder diffraction have been used to study magnetic ordering in Gd5Ir2Bi and Gd5Ir2Sb. Despite the hyperfine fields (Bhf) at the two Gd sites differing by more than a factor of two for both compounds, the moments derived from neutron diffraction are essentially equal in Gd5Ir2Bi. This implies an unusual departure from the commonly assumed scaling between B hf G d and μGd. Neutron powder diffraction shows that Gd5Ir2Bi is a c-axis ferromagnet at 3.6 K. We find no evidence for a FM → AF transition.

  13. IR Windstreaks

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    Windstreaks are features caused by the interaction of wind and topographic landforms. The raised rims and bowls of impact craters causes a complex interaction such that the wind vortex in the lee of the crater can both scour away the surface dust and deposit it back in the center of the lee. If you look closely, you will see evidence of this in a darker 'rim' enclosing a brighter interior.

    This infrared image shows windstreaks in the region between Gordii Dorsum and Amazonis Mensa.

    Image information: IR instrument. Latitude -15.8, Longitude 215 East (145 West). 97 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  14. Two-dimensional X-ray diffraction and transmission electron microscopy study on the effect of magnetron sputtering atmosphere on GaN/SiC interface and gallium nitride thin film crystal structure

    SciTech Connect

    Shen, Huaxiang; Zhu, Guo-Zhen; Botton, Gianluigi A.; Kitai, Adrian

    2015-03-21

    The growth mechanisms of high quality GaN thin films on 6H-SiC by sputtering were investigated by X-ray diffraction (XRD) and scanning transmission electron microscopy (STEM). The XRD θ-2θ scans show that high quality (0002) oriented GaN was deposited on 6H-SiC by reactive magnetron sputtering. Pole figures obtained by 2D-XRD clarify that GaN thin films are dominated by (0002) oriented wurtzite GaN and (111) oriented zinc-blende GaN. A thin amorphous silicon oxide layer on SiC surfaces observed by STEM plays a critical role in terms of the orientation information transfer from the substrate to the GaN epilayer. The addition of H{sub 2} into Ar and/or N{sub 2} during sputtering can reduce the thickness of the amorphous layer. Moreover, adding 5% H{sub 2} into Ar can facilitate a phase transformation from amorphous to crystalline in the silicon oxide layer and eliminate the unwanted (33{sup ¯}02) orientation in the GaN thin film. Fiber texture GaN thin films can be grown by adding 10% H{sub 2} into N{sub 2} due to the complex reaction between H{sub 2} and N{sub 2}.

  15. Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3+x (x=1,2,3) phase change material

    NASA Astrophysics Data System (ADS)

    Kooi, B. J.; De Hosson, J. Th. M.

    2002-10-01

    The crystal structures of GeSb2Te4, Ge2Sb2Te5, and Ge3Sb2Te6 were determined using electron diffraction and high-resolution transmission electron microscopy. The structure determined for the former two crystals deviates from the ones proposed in the literature. These crystal structures were developed jointly upon cooling of liquid Ge2Sb2Te5. A stacking disorder parallel to the basal plane was observed that increases with increasing cooling rates. For the GexSb2Te3+x (x=1,2,3) crystals it is shown that an a,b,c stacking holds with an alternating stacking of x GeTe double layers identically present in binary GeTe and one Te-Sb-Te-Te-Sb- repeat unit also present in binary Sb2Te3. A stacking disorder is a logical consequence of building crystals with these two principal units. On the other hand, it is likely that all stable crystals of the Ge-Sb-Te systems are an ordered sequence of these two units. Some of the implications of these findings of the stable and metastable crystal structures that develop from amorphous Ge2Sb2Te5 are presented so as to understand the crucial crystallization process in Ge2Sb2Te5 phase change material.

  16. Mid-IR laser source using hollow waveguide beam combining

    NASA Astrophysics Data System (ADS)

    Elder, Ian F.; Thorne, Daniel H.; Lamb, Robert A.; Jenkins, R. M.

    2016-03-01

    Hollow waveguide technology is a route to efficient beam combining of multiple laser sources in a compact footprint. It is a technology appropriate for combining free-space or fibre-coupled beams generated by semiconductor, fibre or solidstate laser sources. This paper will present results of a breadboard mid-IR system comprising four laser sources combined using a hollow waveguide optical circuit. In this approach the individual dichroic beam combiner components are held in precision alignment slots in the hollow waveguide circuit and the different input wavelengths are guided between the components to a common output port. The hollow waveguide circuit is formed in the surface of a Macor (machinable glass-ceramic) substrate using precision CNC machining techniques. The hollow waveguides have fundamentally different propagation characteristics to solid core waveguides leading to transmission characteristics close to those of the atmosphere while still providing useful light guidance properties. The transmission efficiency and power handling of the hollow waveguide circuit can be designed to be very high across a broad waveband range. Three of the sources are quantum cascade lasers (QCLs), a semiconductor laser technology providing direct generation of midwave IR output. The combined beams provide 4.2 W of near diffraction-limited output co-boresighted to better than 20 µrad. High coupling efficiency into the waveguides is demonstrated, with negligible waveguide transmission losses. The overall transmission of the hollow waveguide beam combining optical circuit, weighted by the laser power at each wavelength, is 93%. This loss is dominated by the performance of the dichroic optics used to combine the beams.

  17. Structure and catalytic properties of Pt Ir catalysts as a function of different substrate

    NASA Astrophysics Data System (ADS)

    Zecua-Fernández, A.; Gómez-Cortés, A.; Cordero-Borboa, A. E.; Vázquez-Zavala, A.

    2001-10-01

    A series of Pt-Ir catalysts prepared by the impregnation method in three different supports and different atomic concentrations were characterized by conventional transmission electron microscopy (TEM), high resolution electron microscopy (HREM), X-ray diffraction (XRD) and n-hexane contact reaction as a catalytic probe. The reaction products were grouped in linear (hydrogenolysis products), isomers (2- and 3-methilpentane), cyclic (cyclohexane) and aromatic (benzene) hydrocarbons. An increment in hydrogenolysis products was observed as the amount of Ir was increased. This observation was extreme when Al 2O 3 and SiO 2 were used as supports, but it was not so for the case of TiO 2. From TEM results, it was concluded that the metallic particle size is a function of Ir content. From X-ray diffraction analysis, it was found that a unique crystalline phase containing atoms of Pt and Ir precipitates into the specimens under study. This phase was found to have a face-centered cubic structure and a lattice parameter whose value changes as long as the relative amounts of Pt and Ir does. A linear relationship was observed to hold between the lattice parameter of the precipitated phase and the relative concentration of Pt for specimens with metallic weights of 4 and 8% in a SiO 2 support. This result may be taken as a direct experimental evidence of the fact that the crystalline structure of the phase-centered cubic phase found to precipitate in amorphous silica obeys the Vegard's law and therefore, the character of a solid solution Pt( x) Ir(1- x), where x is the Pt molar fraction, can be assigned to the structural nature of this phase. This new phase and the changes recorded in particle size could explain the changes in selectivity and catalytic activity observed in the n-hexane contact reaction.

  18. Exchange enhancement and thermal anneal in Mn76Ir24 bottom-pinned spin valves

    NASA Astrophysics Data System (ADS)

    Li, Haohua; Freitas, P. P.; Wang, Zhenjun; Sousa, J. B.; Gogol, P.; Chapman, J.

    2001-06-01

    Exchange enhancement through thermal anneal in bottom-pinned Mn76Ir24 spin valves is investigated. Samples were fabricated by ion beam deposition (IBD), post-annealed in vacuum (10-6 Torr) at 270 °C for 10 min, then cooled in a 3 kOe applied field. For a bilayer structure, glass/Ta 40 Å/NiFe 30 Å/MnIr 60 Å/CoFe 25 Å/Ta 40 Å, the exchange field (Hex) reaches 1148 Oe (Jex=0.4 erg/cm2) after anneal. X-ray diffraction (XRD) analysis shows strong enhancement of <111> texture upon anneal, while grain size obtained from XRD and transmission electron microscopy for as-deposited and annealed states shows no major change. With increasing MnIr thickness, the exchange field decreases, and blocking temperature (Tb) increases, reaching 295 °C for tMnIr=180 Å. Spin valves built with the same exchange bilayer (Ta 20 Å/NiFe 30 Å/MnIr 60 Å/CoFe 25 Å/Cu 22 Å/CoFe 20 Å/NiFe 40 Å/Ta 40 Å) show Hex=855 Oe (Jex=0.3 erg/cm2) and magnetoresistance (MR)=7.1%. The incorporation of nano-oxide layers in spin valves increases the MR signal to 11%. No signal degradation is found in these specular structures for anneals up to 310 °C.

  19. Keyhole electron diffractive imaging (KEDI).

    PubMed

    De Caro, Liberato; Carlino, Elvio; Vittoria, Fabio Alessio; Siliqi, Dritan; Giannini, Cinzia

    2012-11-01

    Electron diffractive imaging (EDI) relies on combining information from the high-resolution transmission electron microscopy image of an isolated kinematically diffracting nano-particle with the corresponding nano-electron diffraction pattern. Phase-retrieval algorithms allow one to derive the phase, lost in the acquisition of the diffraction pattern, to visualize the actual atomic projected potential within the specimen at sub-ångström resolution, overcoming limitations due to the electron lens aberrations. Here the approach is generalized to study extended crystalline specimens. The new technique has been called keyhole electron diffractive imaging (KEDI) because it aims to investigate nano-regions of extended specimens at sub-ångström resolution by properly confining the illuminated area. Some basic issues of retrieving phase information from the EDI/KEDI measured diffracted amplitudes are discussed. By using the generalized Shannon sampling theorem it is shown that whenever suitable oversampling conditions are satisfied, EDI/KEDI diffraction patterns can contain enough information to lead to reliable phase retrieval of the unknown specimen electrostatic potential. Hence, the KEDI method has been demonstrated by simulations and experiments performed on an Si crystal cross section in the [112] zone-axis orientation, achieving a resolution of 71 pm. PMID:23075611

  20. Individual speckle diffraction based 1D and 2D Random Grating Fabrication for detector and solar energy harvesting applications.

    PubMed

    Bingi, Jayachandra; Murukeshan, Vadakke Matham

    2016-01-01

    Laser speckles and speckle patterns, which are formed by the random interference of scattered waves from optically rough surfaces, have found tremendous applications in a wide range of metrological and biomedical fields. Here, we demonstrate a novel edge diffraction phenomenon of individual speckle for the fabrication of 1D and 2D micron and sub-micron size random gratings. These random gratings exhibit broadband response with interesting diffusive diffraction patterns. As an immediate application for solar energy harvesting, significant reduction in transmission and enhanced absorption in thin "Si-random grating-Si" sandwich structure is demonstrated. This work has multifaceted significance where we exploited the individual speckle diffraction properties for the first time. Besides the solar harvesting applications, random gratings are suitable structures for fabrication of theoretically proposed random quantum well IR detectors and hence expected that this work will augur well for such studies in the near future. PMID:26842242

  1. Individual speckle diffraction based 1D and 2D Random Grating Fabrication for detector and solar energy harvesting applications

    PubMed Central

    Bingi, Jayachandra; Murukeshan, Vadakke Matham

    2016-01-01

    Laser speckles and speckle patterns, which are formed by the random interference of scattered waves from optically rough surfaces, have found tremendous applications in a wide range of metrological and biomedical fields. Here, we demonstrate a novel edge diffraction phenomenon of individual speckle for the fabrication of 1D and 2D micron and sub-micron size random gratings. These random gratings exhibit broadband response with interesting diffusive diffraction patterns. As an immediate application for solar energy harvesting, significant reduction in transmission and enhanced absorption in thin “Si-random grating-Si” sandwich structure is demonstrated. This work has multifaceted significance where we exploited the individual speckle diffraction properties for the first time. Besides the solar harvesting applications, random gratings are suitable structures for fabrication of theoretically proposed random quantum well IR detectors and hence expected that this work will augur well for such studies in the near future. PMID:26842242

  2. Individual speckle diffraction based 1D and 2D Random Grating Fabrication for detector and solar energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Bingi, Jayachandra; Murukeshan, Vadakke Matham

    2016-02-01

    Laser speckles and speckle patterns, which are formed by the random interference of scattered waves from optically rough surfaces, have found tremendous applications in a wide range of metrological and biomedical fields. Here, we demonstrate a novel edge diffraction phenomenon of individual speckle for the fabrication of 1D and 2D micron and sub-micron size random gratings. These random gratings exhibit broadband response with interesting diffusive diffraction patterns. As an immediate application for solar energy harvesting, significant reduction in transmission and enhanced absorption in thin “Si-random grating-Si” sandwich structure is demonstrated. This work has multifaceted significance where we exploited the individual speckle diffraction properties for the first time. Besides the solar harvesting applications, random gratings are suitable structures for fabrication of theoretically proposed random quantum well IR detectors and hence expected that this work will augur well for such studies in the near future.

  3. Enhanced monolithic diffraction gratings with high efficiency and reduced polarization sensitivity for remote sensing applications

    NASA Astrophysics Data System (ADS)

    Triebel, Peter; Diehl, Torsten; Moeller, Tobias; Gatto, Alexandre; Pesch, Alexander; Erdmann, Lars H.; Burkhardt, Matthias; Kalies, Alexander

    2015-10-01

    Spectral imaging systems lead to enhanced sensing properties when the sensing system provides sufficient spectral resolution to identify materials from its spectral reflectance signature. The performance of diffraction gratings provides an initial way to improve instrumental resolution. Thus, subsequent manufacturing techniques of high quality gratings are essential to significantly improve the spectral performance. The ZEISS unique technology of manufacturing real-blazed profiles and as well as lamellar profiles comprising transparent substrates is well suited for the production of transmission gratings. In order to reduce high order aberrations, aspherical and free-form surfaces can be alternatively processed to allow more degrees of freedom in the optical design of spectroscopic instruments with less optical elements and therefore size and weight advantages. Prism substrates were used to manufacture monolithic GRISM elements for UV to IR spectral range. Many years of expertise in the research and development of optical coatings enable high transmission anti-reflection coatings from the DUV to the NIR. ZEISS has developed specially adapted coating processes (Ion beam sputtering, ion-assisted deposition and so on) for maintaining the micro-structure of blazed gratings in particular. Besides of transmission gratings, numerous spectrometer setups (e.g. Offner, Rowland circle, Czerny-Turner system layout) working on the optical design principles of reflection gratings. This technology steps can be applied to manufacture high quality reflection gratings from the EUV to the IR applications with an outstanding level of low stray light and ghost diffraction order by employing a combination of holography and reactive ion beam etching together with the in-house coating capabilities. We report on results of transmission gratings on plane and curved substrates and GRISM elements with enhanced efficiency of the grating itself combined with low scattered light in the angular

  4. The Origin of Capacity Fade in the Li2MnO3·LiMO2 (M = Li, Ni, Co, Mn) Microsphere Positive Electrode: An Operando Neutron Diffraction and Transmission X-ray Microscopy Study.

    PubMed

    Chen, Chih-Jung; Pang, Wei Kong; Mori, Tatsuhiro; Peterson, Vanessa K; Sharma, Neeraj; Lee, Po-Han; Wu, She-Huang; Wang, Chun-Chieh; Song, Yen-Fang; Liu, Ru-Shi

    2016-07-20

    The mechanism of capacity fade of the Li2MnO3·LiMO2 (M = Li, Ni, Co, Mn) composite positive electrode within a full cell was investigated using a combination of operando neutron powder diffraction and transmission X-ray microscopy methods, enabling the phase, crystallographic, and morphological evolution of the material during electrochemical cycling to be understood. The electrode was shown to initially consist of 73(1) wt % R3̅m LiMO2 with the remaining 27(1) wt % C2/m Li2MnO3 likely existing as an intergrowth. Cracking in the Li2MnO3·LiMO2 electrode particle under operando microscopy observation was revealed to be initiated by the solid-solution reaction of the LiMO2 phase on charge to 4.55 V vs Li(+)/Li and intensified during further charge to 4.7 V vs Li(+)/Li during the concurrent two-phase reaction of the LiMO2 phase, involving the largest lattice change of any phase, and oxygen evolution from the Li2MnO3 phase. Notably, significant healing of the generated cracks in the Li2MnO3·LiMO2 electrode particle occurred during subsequent lithiation on discharge, with this rehealing being principally associated with the solid-solution reaction of the LiMO2 phase. This work reveals that while it is the reduction of lattice size of electrode phases during charge that results in cracking of the Li2MnO3·LiMO2 electrode particle, with the extent of cracking correlated to the magnitude of the size change, crack healing is possible in the reverse solid-solution reaction occurring during discharge. Importantly, it is the phase separation during the two-phase reaction of the LiMO2 phase that prevents the complete healing of the electrode particle, leading to pulverization over extended cycling. This work points to the minimization of behavior leading to phase separation, such as two-phase and oxygen evolution, as a key strategy in preventing capacity fade of the electrode. PMID:27314640

  5. Diffraction encoded position measuring apparatus

    DOEpatents

    Tansey, Richard J.

    1991-01-01

    When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection.

  6. Diffraction encoded position measuring apparatus

    DOEpatents

    Tansey, R.J.

    1991-09-24

    When a lightwave passes through a transmission grating, diffracted beams appear at the output or opposite side of the grating that are effectively Doppler shifted in frequency (phase) whereby a detector system can compare the phase of the zero order and higher order beams to obtain an indication of position. Multiple passes through the grating increase resolution for a given wavelength of a laser signal. The resolution can be improved further by using a smaller wavelength laser to generate the grating itself. Since the grating must only have a pitch sufficient to produce diffracted orders, inexpensive, ultraviolet wavelength lasers can be utilized and still obtain high resolution detection. 3 figures.

  7. ALBERMARLE PAMLICO IR 2002

    EPA Science Inventory

    The 2002 Albermarle Pamlico Implementation Review (IR) highlights recent successes and challenges with the estuary program. Various components within the IR include: CCMP implementation, outlining priority management actions, public involvement, stakeholder contribution, and limi...

  8. IR laser-induced protein crystal transformation

    SciTech Connect

    Kiefersauer, Reiner Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-05-01

    A novel method and the associated instrumentation for improving crystalline order (higher resolution of X-ray diffraction and reduced mosaicity) of protein crystals by precisely controlled heating is demonstrated. Crystal transformation is optically controlled by a video system. A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress.

  9. Investigation of PdIr/C electrocatalysts as anode on the performance of direct ammonia fuel cell

    NASA Astrophysics Data System (ADS)

    Assumpção, M. H. M. T.; da Silva, S. G.; De Souza, R. F. B.; Buzzo, G. S.; Spinacé, E. V.; Santos, M. C.; Neto, A. O.; Silva, J. C. M.

    2014-12-01

    This work investigates the ammonia electro-oxidation considering electrochemical and direct ammonia fuel cell (DAFC) experiments. The working electrodes/anodes are composed of Pd/C, PdIr/C (90:10, 70:30, 50:50, 30:70 and 10:90 atomic ratios) and Ir/C. Solutions of 1 mol L-1 NH4OH and 1 mol L-1 KOH were used for electrochemical experiments while 1.0, 3.0 and 5.0 mol L-1 NH4OH in 1.0 mol L-1 KOH were used in DAFC. X-ray diffraction analysis of PdIr/C electrocatalysts suggests the formation of PdIr alloy, while transmission electron micrographs show the average particle diameters between 4.6 and 6.2 nm. Electrochemical experiments indicate PdIr/C 30:70 as the best electrocatalyst in accordance with DAFC. The maximum power densities obtained with PdIr/C 30:70 as anode using 5 mol L-1 NH4OH and 1 mol L-1 KOH at 40 °C are 60% and 30% higher than the ones obtained with Pd/C and Ir/C electrocatalysts, respectively. The enhanced synergic effect in this specific composition may be assigned to an optimal ratio of palladium sites that dehydrogenates ammonia at lower overpotential with the lower surface coverage of Nads on iridium. Furthermore, electronic effect between palladium and iridium might also contribute to the decrease of poisoning on catalyst surface by Nads.

  10. IR laser-induced protein crystal transformation

    PubMed Central

    Kiefersauer, Reiner; Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-01-01

    A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress. PMID:24816092

  11. IOT Overview: IR Instruments

    NASA Astrophysics Data System (ADS)

    Mason, E.

    In this instrument review chapter the calibration plans of ESO IR instruments are presented and briefly reviewed focusing, in particular, on the case of ISAAC, which has been the first IR instrument at VLT and whose calibration plan served as prototype for the coming instruments.

  12. Diffraction by dual-period gratings.

    PubMed

    Skigin, Diana C; Depine, Ricardo A

    2007-03-20

    The dynamical characteristics of dual-period perfectly conducting gratings are explored. Gratings with several grooves (reflection) or slits (transmission) within each period are considered. A scalar approach is proposed to derive the general characteristics of the diffracted response. It was found that compound gratings can be designed to cancel as well as to intensify a given diffraction order. These preliminary estimations for finite gratings are validated by numerical examples for infinitely periodic reflection and transmission gratings with finite thickness, performed using an extension of the rigorous modal method to compound gratings, for both polarization cases. PMID:17334426

  13. IR Hot Wave

    SciTech Connect

    Graham, T. B.

    2010-04-01

    The IR Hot Wave{trademark} furnace is a breakthrough heat treatment system for manufacturing metal components. Near-infrared (IR) radiant energy combines with IR convective heating for heat treating. Heat treatment is an essential process in the manufacture of most components. The controlled heating and cooling of a metal or metal alloy alters its physical, mechanical, and sometimes chemical properties without changing the object's shape. The IR Hot Wave{trademark} furnace offers the simplest, quickest, most efficient, and cost-effective heat treatment option for metals and metal alloys. Compared with other heat treatment alternatives, the IR Hot Wave{trademark} system: (1) is 3 to 15 times faster; (2) is 2 to 3 times more energy efficient; (3) is 20% to 50% more cost-effective; (4) has a {+-}1 C thermal profile compared to a {+-}10 C thermal profile for conventional gas furnaces; and (5) has a 25% to 50% smaller footprint.

  14. Metagratings for Diffraction Based, Compact, Holographic Imaging

    NASA Astrophysics Data System (ADS)

    Inampudi, Sandeep; Podolskiy, Viktor; Multiscale Electromagnetics Group Team

    2013-03-01

    Recent developments in semiconductor technology brought to life a new generation of highly-compact visible-frequency cameras. Unfortunately, straight forward extension of this progress to low-frequency domains (such as mid-IR imaging) is impossible since the pixel size at these frequencies is limited by free-space diffraction limit. Here we present an approach to realize highly-compact imaging systems at lower frequencies. Our approach takes advantage of high refractive index of materials commonly utilized in semiconductor detectors of mid-IR radiation, accompanied by metagratings, structures with engineered diffraction properties, to achieve a 10-fold reduction in the pixel size. In contrast to conventional refraction-based imaging, the approach essentially produces a digital hologram - a 2D projection of the 3D optical field, enabling a post-imaging ``refocusing'' of the picture. The perspectives of numerical recovery of the optical field and the stability of such recovery are discussed.

  15. X-Ray Diffraction.

    ERIC Educational Resources Information Center

    Smith, D. K.; Smith, K. L.

    1980-01-01

    Reviews applications in research and analytical characterization of compounds and materials in the field of X-ray diffraction, emphasizing new developments in applications and instrumentation in both single crystal and powder diffraction. Cites 414 references. (CS)

  16. Atomic structure of Zr-Cu glassy alloys and detection of deviations from ideal solution behavior with Al addition by x-ray diffraction using synchrotron light in transmission

    NASA Astrophysics Data System (ADS)

    Georgarakis, K.; Yavari, A. R.; Louzguine-Luzgin, D. V.; Antonowicz, J.; Stoica, M.; Li, Y.; Satta, M.; LeMoulec, A.; Vaughan, G.; Inoue, A.

    2009-05-01

    The atomic structure of Zr-Cu binary amorphous alloys was studied using real space pair distribution functions derived from x-ray diffraction. The structure can be modeled by an ideal solution approximation because of relatively weak Cu-Zr atomic interactions. Addition of Al to Zr-Cu metallic glasses modifies the atomic structure in the short and medium range order because of the strongly attractive interaction between Al and Zr atoms. These interactions generate strong deviations from the ideal solution behavior.

  17. Fabrication of (111)-oriented Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3}/SrTiO{sub 3} superlattices—A designed playground for honeycomb physics

    SciTech Connect

    Hirai, Daigorou; Matsuno, Jobu; Takagi, Hidenori

    2015-04-01

    We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca{sub 0.5}Sr{sub 0.5}IrO{sub 3} perovskite and two layers of SrTiO{sub 3} perovskite on SrTiO{sub 3}(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  18. Fabrication of (111)-oriented Ca0.5Sr0.5IrO3/SrTiO3 superlattices—A designed playground for honeycomb physics

    NASA Astrophysics Data System (ADS)

    Hirai, Daigorou; Matsuno, Jobu; Takagi, Hidenori

    2015-04-01

    We report the fabrication of (111)-oriented superlattice structures with alternating 2m-layers (m = 1, 2, and 3) of Ca0.5Sr0.5IrO3 perovskite and two layers of SrTiO3 perovskite on SrTiO3(111) substrates. In the case of m = 1 bilayer films, the Ir sub-lattice is a buckled honeycomb, where a topological state may be anticipated. The successful growth of superlattice structures on an atomic level along the [111] direction was clearly demonstrated by superlattice reflections in x-ray diffraction patterns and by atomically resolved transmission electron microscope images. The ground states of the superlattice films were found to be magnetic insulators, which may suggest the importance of electron correlations in Ir perovskites in addition to the much discussed topological effects.

  19. Infrared Measurements of Possible IR Filter Materials

    SciTech Connect

    Koller,D.; Ediss, G.; Mihaly, L.; Carr, G.

    2006-01-01

    A Fourier Transform Infrared Spectrometer (FTS) was used to obtain the transmission spectra of candidate materials for use as infrared (IR) filters in cryogenic receivers. The data cover the range from 50 cm-1 ({approx}1.5 THz), well below the peak of the 300 K black body spectrum, to 5000 cm-1 ({approx}150 THz), Z-cut quartz, Gore-Tex, Zitex G and Zitex A, High Density Polyethylene (HDPE), Teflon (PTFE), Fluorogold and Black Polyethylene were measured. The relative effectiveness of each material as a filter is determined by integrating the transmission spectrum multiplied by the Planck distribution to obtain a normalized attenuation for the mid-IR band. Measurements at both room temperature and 8 K are compared.

  20. CHARLOTTE HARBOR IR, 2002

    EPA Science Inventory

    The 2002 Charlotte Harbor Implementation Review (IR) summarizes the progress and challenges ahead for the Charlotte Harbor National Estuary Program (CHNEP). The implementation review report requires seven components: Status of CCMP implementation (programmatic progress); Environm...

  1. Far-field infrared super-resolution microscopy using picosecond time-resolved transient fluorescence detected IR spectroscopy

    NASA Astrophysics Data System (ADS)

    Sakai, Makoto; Kawashima, Yasutake; Takeda, Akihiro; Ohmori, Tsutomu; Fujii, Masaaki

    2007-05-01

    A new far-field infrared super-resolution microscopy combining laser fluorescence microscope and picosecond time-resolved transient fluorescence detected IR (TFD-IR) spectroscopy is proposed. TFD-IR spectroscopy is a kind of IR-visible/UV double resonance spectroscopy, and detects IR transitions by the transient fluorescence due to electronic transition originating from vibrationally excited level populated by IR light. IR images of rhodamine-6G solution and of fluorescent beads were clearly observed by monitoring the transient fluorescence. Super-resolution twice higher than the diffraction limit for IR light was achieved. The IR spectrum due to the transient fluorescence was also measured from spatial domains smaller than the diffraction limit.

  2. Magnetic symmetries in neutron and resonant x-ray Bragg diffraction patterns of four iridium oxides

    NASA Astrophysics Data System (ADS)

    Lovesey, S. W.; Khalyavin, D. D.; Manuel, P.; Chapon, L. C.; Cao, G.; Qi, T. F.

    2012-12-01

    The magnetic properties of Sr2IrO4, Na2IrO3, Sr3Ir2O7 and CaIrO3 are discussed, principally in the light of experimental data in recent literature for Bragg intensities measured in x-ray diffraction with enhancement at iridium L-absorption edges. The electronic structure factors we report, which incorporate parity-even and acentric entities, serve the immediate purpose of making full use of crystal and magnetic symmetry to refine our knowledge of the magnetic properties of the four iridates from resonant x-ray diffraction data. They also offer a platform on which to interpret future investigations, using dichroic signals, resonant x-ray diffraction and neutron diffraction, for example, as well as ab initio calculations of electronic structure. Unit-cell structure factors, suitable for x-ray Bragg diffraction enhanced by an electric dipole-electric dipole (E1-E1) event, reveal exactly which iridium multipoles are visible, e.g., a magnetic dipole parallel to the crystal c-axis (z-axis) and an electric quadrupole with yz-like symmetry in the specific case of CaIrO3. Magnetic space-groups are assigned to Sr2IrO4, Sr3Ir2O7 and CaIrO3, namely, PIcca, PAban and Cm‧cm‧, respectively, in the Belov-Neronova-Smirnova notation. The assignment for Sr2IrO4 is possible because of our new high-resolution neutron diffraction data, gathered on a powder sample. In addition, the new data are used to show that the ordered magnetic moment of an Ir4+ ion in Sr2IrO4 does not exceed 0.29(4) μB. Na2IrO3 has two candidate magnetic space-groups that are not resolved with currently available resonant x-ray data.

  3. Growth and termination of a rutile IrO2(100) layer on Ir(111)

    NASA Astrophysics Data System (ADS)

    Rai, Rahul; Li, Tao; Liang, Zhu; Kim, Minkyu; Asthagiri, Aravind; Weaver, Jason F.

    2016-10-01

    We investigated the oxidation of Ir(111) by gas-phase oxygen atoms at temperatures between 500 and 625 K using temperature programmed desorption (TPD), low energy electron diffraction (LEED), low energy ion scattering spectroscopy (LEISS) and density functional theory (DFT) calculations. We find that a well-ordered surface oxide with (√ 3 × √ 3)R30° periodicity relative to Ir(111) develops prior to the formation of a rutile IrO2(100) layer. The IrO2(100) layer reaches a saturation thickness of about four oxide layers under the oxidation conditions employed, and decomposes during TPD to produce a single, sharp O2 desorption peak at ~ 770 K. Favorable lattice matching at the oxide-metal interface is likely responsible for the preferential growth of the IrO2(100) facet during the initial oxidation of Ir(111), with the resulting coincidence lattice generating a clear (6 × 1) moiré pattern in LEED. Temperature programmed reaction spectroscopy (TPRS) experiments reveal that CO and H2O molecules bind only weakly on the IrO2(100) surface and LEISS measurements show that the oxide surface is highly enriched in O-atoms. These characteristics provide strong evidence that the rutile IrO2(100) layer is oxygen-terminated, and thus lacks reactive Ir atoms that can strongly bind molecular adsorbates. Oxygen binding energies predicted by DFT suggest that on-top O-atoms will remain adsorbed on IrO2(100) at temperatures up to ~ 625 K, thus supporting the conclusion that the rutile IrO2 layer grown in our experiments is oxygen-terminated. As such, the appearance of only a single O2 TPD peak indicates that the singly coordinate, on-top O-atoms remain stable on the IrO2(100) surface up to temperatures at which the oxide layer begins to thermally decompose.

  4. Eyeglass. 1. Very large aperture diffractive telescopes.

    PubMed

    Hyde, R A

    1999-07-01

    The Eyeglass is a very large aperture (25-100-m) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope s large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently launchable (lightweight, packagable, and deployable) it and virtually eliminates the traditional, very tight surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope s eyepiece; the Eyeglass can provide diffraction-limited imaging with either single-band (Deltalambda/lambda approximately 0.1), multiband, or continuous spectral coverage. PMID:18323902

  5. Harmonic diffractive lenses

    SciTech Connect

    Sweeney, D.W.; Sommargren, G.E.

    1995-05-10

    The harmonic diffractive lens is a diffractive imaging lens for which the optical path-length transition between adjacent facets is an integer multiple {ital m} of the design wavelength {lambda}{sub 0}. The total lens thickness in air is {ital m}{lambda}{sub 0}/({ital n} {minus} 1), which is {ital m} times thicker than the so-called modulo 2{pi} diffractive lens. Lenses constructed in this way have hybrid properties of both refractive and diffractive lenses. Such a lens will have a diffraction-limited, common focus for a number of discrete wavelengths across the visible spectrum. A 34.75-diopter, 6-mm-diameter lens is diamond turned in aluminum and replicated in optical materials. The sag of the lens is 23 {mu}m. Modulation transfer function measurements in both monochromatic and white light verify the performance of the lens. The lens approaches the diffraction limit for 10 discrete wavelengths across the visible spectrum.

  6. Shingles Transmission

    MedlinePlus

    ... on Shingles Immunization Action Coalition Chickenpox Q&As Transmission Language: English Español (Spanish) Recommend on Facebook Tweet ... Prevention & Treatment Related Pages Preventing Varicella Zoster Virus Transmission in Healthcare Settings Related Links Medline Plus NIH ...

  7. BUZZARDS BAY IR, 2002

    EPA Science Inventory

    The 2002 Buzzards Bay Implementation Review (IR) summarizes the progress and challenges ahead for the Buzzards Bay Project. Major new completed actions during the past two years include: designation of Buzzards Bay as a no discharge area in August 2000; full support by the Massac...

  8. Concomitant charge-density-wave and unit-cell-doubling structural transitions in Dy5Ir4Si10

    NASA Astrophysics Data System (ADS)

    Lee, M. H.; Chen, C. H.; Tseng, C. M.; Lue, C. S.; Kuo, Y. K.; Yang, H. D.; Chu, M.-W.

    2014-05-01

    The tetragonal rare-earth transition-metal silicide system with three-dimensional crystallographic structure R5T4Si10, where R is Dy, Ho, Er, Tm, and Lu, and T=Ir and Rh, has been shown to exhibit fascinating charge-density-wave (CDW) phase transitions, a phenomenon largely found in otherwise low-dimensional systems. In this study, we report the investigations of CDW in Dy5Ir4Si10 at different temperatures using transmission electron microscopy techniques including electron diffraction and dark-field imaging. Incommensurate superlattice spots along the c axis were observed in the electron-diffraction patterns when the sample was cooled below the CDW transition temperature at ˜208 K. CDW becomes commensurate with further cooling and configurations of CDW dislocations convincingly show that the CDW phase transition is accompanied by a concomitant cell-doubling crystallographic structural phase transition. Intriguingly, the cell-doubling transition is featured by a broken inversion symmetry along the c axis and a disparity in the CDW-modulation vectors with opposite signs, which gives rise to two sets of CDW domains with reversed contrasts. The profound physics underlining this notable domain-contrast behavior is discussed.

  9. Diffraction by cold atoms

    NASA Astrophysics Data System (ADS)

    Strauch, F.; Gomer, V.; Schadwinkel, H.; Ueberholz, B.; Haubrich, D.; Meschede, D.

    1998-01-01

    We have observed diffraction of a laser probe beam by a trapped sample of cold atoms. The effect is only visible in the vicinity of a resonance line. The observed diffraction pattern arises from interference of the incident and scattered light wave, allowing reconstruction of geometric properties of the trapped sample from the holographic record.

  10. Diffraction Results from CDF

    SciTech Connect

    Goulianos, Konstantin

    2012-04-01

    We present final results by the CDF II collaboration on diffractive W and Z production, report on the status of ongoing analyses on diffractive dijet production and on rapidity gaps between jets, and briefly summarize results obtained on exclusive production pointing to their relevance to calibrating theoretical models used to predict exclusive Higgs-boson production at the LHC.

  11. FT-IR microscopical analysis with synchrotron radiation: The microscope optics and system performance

    SciTech Connect

    Reffner, J.A.; Martoglio, P.A.; Williams, G.P.

    1995-01-01

    When a Fourier transform infrared (FT-IR) microspectrometer was first interfaced with the National Synchrotron Light Source (NSLS) in September 1993, there was an instant realization that the performance at the diffraction limit had increased 40-100 times. The synchrotron source transformed the IR microspectrometer into a true IR microprobe, providing high-quality IR spectra for probe diameters at the diffraction limit. The combination of IR microspectroscopy and synchrotron radiation provides a powerful new tool for molecular spectroscopy. The ability to perform IR microspectroscopy with synchrotron radiation is still under development at Brookhaven National Laboratory, but several initial studies have been completed that demonstrate the broad-ranging applications of this technology and its potential for materials characterization.

  12. Exchange enhancement and thermal anneal in Mn{sub 76}Ir{sub 24} bottom-pinned spin valves

    SciTech Connect

    Li, Haohua; Freitas, P. P.; Wang, Zhenjun; Sousa, J. B.; Gogol, P.; Chapman, J.

    2001-06-01

    Exchange enhancement through thermal anneal in bottom-pinned Mn{sub 76}Ir{sub 24} spin valves is investigated. Samples were fabricated by ion beam deposition (IBD), post-annealed in vacuum (10{sup {minus}6}Torr) at 270{degree}C for 10 min, then cooled in a 3 kOe applied field. For a bilayer structure, glass/Ta 40 Aa/NiFe 30 Aa/MnIr 60 Aa/CoFe 25 Aa/Ta 40 Aa, the exchange field (H{sub ex}) reaches 1148 Oe (J{sub ex}=0.4erg/cm{sup 2}) after anneal. X-ray diffraction (XRD) analysis shows strong enhancement of {l_angle}111{r_angle} texture upon anneal, while grain size obtained from XRD and transmission electron microscopy for as-deposited and annealed states shows no major change. With increasing MnIr thickness, the exchange field decreases, and blocking temperature (T{sub b}) increases, reaching 295{degree}C for t{sub MnIr}=180Aa. Spin valves built with the same exchange bilayer (Ta 20 Aa/NiFe 30 Aa/MnIr 60 Aa/CoFe 25 Aa/Cu 22 Aa/CoFe 20 Aa/NiFe 40 Aa/Ta 40 Aa) show H{sub ex}=855Oe (J{sub ex}=0.3erg/cm{sup 2}) and magnetoresistance (MR)=7.1%. The incorporation of nano-oxide layers in spin valves increases the MR signal to 11%. No signal degradation is found in these specular structures for anneals up to 310{degree}C. {copyright} 2001 American Institute of Physics.

  13. Linear-dichroic infrared spectral (IR-LD) analysis of codeine and its derivatives

    NASA Astrophysics Data System (ADS)

    Koleva, Bojidarka; Kolev, Tsonko; Bakalska, Rumyana

    2007-05-01

    By means of IR-LD spectroscopy of oriented as suspension in nematic liquid crystal solids, a detailed IR-bands assignment and a stereo-structural prediction of codeine, codeinone and N-norcodeine have been carried out. The data are compared with known crystallographic ones of codeine and codeinone obtained by single crystal X-ray diffraction.

  14. IR spectroscopic investigations of amoxicillin trihydrate, included in the technological models sirup granules in ethylcellulose

    NASA Astrophysics Data System (ADS)

    Gasheva, L. M.; Kalinkova, G.; Minkov, E.; Krestev, V.

    1984-03-01

    Employing IR spectroscopy some technological models of amoxicillin trihydrate, included in ethyl-, methyl-, carboxymethyl- and methylhydroxyethyl-cellulose have been studied. Interactions were established only between amoxicillin trihydrate and ethylcellulose. The IR absorption spectra suggest a H-bonded antibiotic with hydroxyl groups in the ethylcellulose molecule. The IR spectral differences observed are not due to polymorphic transformation; this was proved by X-ray powder diffraction.

  15. Glass formation and optical properties of Ge-Te-Ga-CuI far-IR transmitting chalcogenide glasses

    NASA Astrophysics Data System (ADS)

    He, Yuju; Wang, Xunsi; Nie, Qiuhua; Xu, Yinsheng; Xu, Tiefeng; Dai, Sixun

    2013-09-01

    To discover the signs of life on terrestrial planets, we must accurately detect the existence of CO2, which has two vibrational absorption bands at 4 μm and 16 μm. Therefore optical materials be able to transmit light far beyond 20 μm are essential for manufacturing these detectors. In this paper, a series of Ge-Te-Ga-CuI far-IR transmitting chalcogenide glasses were synthesized by conventional melt-quenching method and their glass-forming region was determined. Properties measurements including X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), Vis-NIR and IR transmitting spectra were performed on glasses. The results of XRD measurements confirmed the amorphous state of studied glasses. With the help of Ga and CuI, these glasses have high glass transition temperature Tg (>175 °C), indicating their good thermal stability. The allowed indirect transition of samples was also calculated according to the Tauc equation. The infrared transmission spectra measured by Fourier transform infrared spectrometer (FTIR) show that these glasses all have wide optical transmitting window from 1.68 to 25 μm revealing that it may have great potential for application in far-IR material fields.

  16. IR fiber optic sensing on biological tissue

    NASA Astrophysics Data System (ADS)

    Bindig, Uwe; Gersonde, I.; Meinke, M.; Becker, Y.; Mueller, Gerhard

    2003-10-01

    A diagnostic method is described to detect differences between diseased and normal tissue from bladder carcinoma by FTIR-microspectroscopy and fiber-optics methods. Regions of interest on 10 μm thin tissue sections were mapped using an IR-microscope in transmission mode. Afterwards the specimens were analyzed using standard pathological techniques. Quadratic discriminant as well as correlation analysis was applied for data analysis. IR optical fibers, not only allowed measurements to be made in the attenuated total reflectance (ATR)-mode but also absorption measurements to be carried out at a remote location. The IR-sensor is in contact with the sample which shows characteristic absorption lines. This method can be used to determine the absorption of a sample in a non-destructive manner. In this paper we report our efforts to develop a fiber-optic infrared sensor to differentiate between malignant and healthy tissue in vivo. Silver halide fibers and a special sensor tip were used for the ATR measurements on human tissue specimens. The results indicate that IR-spectrometry will be a useful tool for bio-diagnostics.

  17. Calculating incoherent diffraction MTF

    NASA Astrophysics Data System (ADS)

    Friedman, Melvin; Vizgaitis, Jay

    2008-04-01

    The incoherent diffraction MTF plays an increasingly important role in the range performance of imaging systems as the wavelength increases and the optical aperture decreases. Accordingly, all NVESD imager models have equations that describe the incoherent diffraction MTF of a circular entrance pupil. NVThermIP, a program which models thermal imager range performance, has built in equations which analytically model the incoherent diffraction MTF of a circular entrance pupil and has a capability to input a table that describes the MTF of other apertures. These can be calculated using CODE V, which can numerically calculate the incoherent diffraction MTF in the vertical or horizontal direction for an arbitrary aperture. However, we are not aware of any program that takes as input a description of the entrance pupil and analytically outputs equations that describe the incoherent diffraction MTF. This work explores the effectiveness of Mathematica to analytically and numerically calculate the incoherent diffraction MTF for an arbitrary aperture. In this work, Mathematica is used to analytically and numerically calculate the incoherent diffraction MTF for a variety of apertures and the results are compared with CODE V calculations.

  18. Nuclear IRS-1 and Cancer

    PubMed Central

    Reiss, Krzysztof; Valle, Luis Del; Lassak, Adam; Trojanek, Joanna

    2011-01-01

    The family of insulin receptor substrates (IRS) consists of four proteins (IRS-1 - IRS-4), which were initially characterized as typical cytosolic adaptor proteins involved in insulin receptor (IR) and insulin-like growth factor I receptor (IGF-IR) signaling. The first cloned and characterized member of the IRS family, IRS-1, has predicted molecular weight of 132 kDa, however, as a result of its extensive serine phosphorylation it separates on a SDS gel as a band of approximately 160–185 kDa. In addition to its metabolic and growth-promoting functions, IRS-1 is also suspected to play a role in malignant transformation. The mechanism by which IRS-1 supports tumor growth is not fully understood, and the argument that IRS-1 merely amplifies the signal from the IGF-1R and/or IR requires further investigation. Almost a decade ago, we reported the presence of nuclear IRS-1 in medulloblastoma clinical samples, which express viral oncoprotein, large T-antigen of human polyomavirus JC (JCV T-antigen). This first demonstration of nuclear IRS-1 was confirmed in several other laboratories. The nuclear IRS-1 was also detected by cells expressing the SV40 T-antigen, v-Src, in immortalized fibroblasts stimulated with IGF-I, in hepatocytes, 32D cells, and in an osteosarcoma cell line. More recently, nuclear IRS-1 was detected in breast cancer cells in association with estrogen receptor alpha (ERα), and in JC virus negative medulloblastoma cells expressing ERβ, further implicating nuclear IRS-1 in cellular transformation. Here, we discuss how nuclear IRS-1 acting on DNA repair fidelity, transcriptional activity, and cell growth can support tumor development and progression. PMID:22454254

  19. HWIL IR imaging testing

    NASA Astrophysics Data System (ADS)

    Vinson, R. J.; Passwater, R. D.

    1981-03-01

    The Army simulator facilities are presently configured to conduct hardware-in-the-loop mission tasks on the HELLFIRE and COPPERHEAD missile systems. These systems presently use a LASER seeker. The facility is an ideal candidate to be converted to include infrared (IR) seekers used on the TGSM system. This study investigates the possibility and impact of a facility update. This report documents the feasibility of developing a hardware-in-the-loop (HWIL) hybrid simulation incorporating infrared IR seekers used for the Assault Breaker program. Other hardware to be considered are the autopilot, signal conditioning, signal processing, and actuators which may be integrated into the system simulation. Considerations are given to replacing all or elements of hardware while substituting math models in the system simulation.

  20. Synthesis, growth, spectral, X-ray diffraction, magnetic and thermal studies of metal-organic complex: Diiodobis(2-aminopyridine)Cadmium(II) single crystal

    NASA Astrophysics Data System (ADS)

    Venkatesan, G.; Anandha Babu, G.; Ramasamy, P.; Rajnikant

    2013-06-01

    The metal-organic hybrid complex, [Cd(2ap)2I2] (DIAC), (2ap = 2-aminopyridine) was synthesized, DIAC single crystal has been grown and characterized by FT-IR, FT-Raman, FT-1H NMR, single crystal X-ray diffraction, high resolution X-ray diffraction (HRXRD), UV-Vis-NIR transmission, magnetic and thermal studies. The metal-ligand formation of the title complex was analyzed by FT-IR, FT-Raman and 1H NMR spectroscopic studies. The DIAC crystallizes in monoclinic crystal system, space group P21/n. The coordination geometry around the Cd(II) center is a distorted tetrahedral. The single-crystal structure analysis showed that DIAC displayed three-dimensional structures containing inorganic-organic motifs with two-dimensional layers pillar-connected through hydrogen bonding framework. The high resolution X-ray diffraction studies (HRXRD) reveals that the crystalline perfection of as grown single crystal is fairly good. Thermal stability of title compound was studied by TG/DTA analysis.

  1. Hard diffraction at CDF

    SciTech Connect

    Melese, P.L.; CDF Collaboration

    1996-07-01

    We present new evidence for events with a rapidity gap between jets in {bar p}-p collisions at {radical}s = 1.8 TeV based on data collected by triggering the Collider Detector at Fermilab on two high transverse momentum forward jets and results of a search for diffractive W{+-} and dijet production where diffraction is tagged by the rapidity gap technique. We also present the results of a search for diffractive dijets using data collected by triggering on a very forward particle in the recently installed roman-pot detectors. The dijet events exhibit additional diffractive characteristics such as rapidity gaps and boosted center of mass system, however the recoil antiproton measured in the roman-pots is in a regime in which the non- pomeron contribution is significant.

  2. Reflective diffraction grating

    DOEpatents

    Lamartine, Bruce C.

    2003-06-24

    Reflective diffraction grating. A focused ion beam (FIB) micromilling apparatus is used to store color images in a durable medium by milling away portions of the surface of the medium to produce a reflective diffraction grating with blazed pits. The images are retrieved by exposing the surface of the grating to polychromatic light from a particular incident bearing and observing the light reflected by the surface from specified reception bearing.

  3. Status of the Neutron Imaging and Diffraction Instrument IMAT

    NASA Astrophysics Data System (ADS)

    Kockelmann, Winfried; Burca, Genoveva; Kelleher, Joe F.; Kabra, Saurabh; Zhang, Shu-Yan; Rhodes, Nigel J.; Schooneveld, Erik M.; Sykora, Jeff; Pooley, Daniel E.; Nightingale, Jim B.; Aliotta, Francesco; Ponterio, Rosa C.; Salvato, Gabriele; Tresoldi, Dario; Vasi, Cirino; McPhate, Jason B.; Tremsin, Anton S.

    A cold neutron imaging and diffraction instrument, IMAT, is currently being constructed at the ISIS second target station. IMAT will capitalize on time-of-flight transmission and diffraction techniques available at a pulsed neutron source. Analytical techniques will include neutron radiography, neutron tomography, energy-selective neutron imaging, and spatially resolved diffraction scans for residual strain and texture determination. Commissioning of the instrument will start in 2015, with time-resolving imaging detectors and two diffraction detector prototype modules. IMAT will be operated as a user facility for material science applications and will be open for developments of time-of-flight imaging methods.

  4. Powder Diffraction: By Decades

    NASA Astrophysics Data System (ADS)

    David, William I. F.

    This introductory chapter reviews the first 100 years of powder diffraction, decade by decade, from the earliest X-ray powder diffraction measurements of the crystal structure of graphite through to the diversity and complexity of twenty-first century powder diffraction. Carbon features as an illustrative example throughout the discussion of these ten decades from graphite and the disorder of carbon black through to lonsdaleite, the elusive hexagonal polymorph of diamond, and C60, the most symmetrical of molecules. Electronics and computing have played a leading role in the development of powder diffraction, particularly over the past 60 years, and the Moore's Law decade-by-decade rise in computing power is clear in the increasing complexity of powder diffraction experiments and material systems that can be studied. The chapter concludes with a final discussion of decades - the four decades of length-scale from the ångstrom to the micron that not only represent the domain of powder diffraction but are also the distances that will dominate twenty-first century science and technology.

  5. Transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  6. Transmission eigenvalues

    NASA Astrophysics Data System (ADS)

    Cakoni, Fioralba; Haddar, Houssem

    2013-10-01

    In inverse scattering theory, transmission eigenvalues can be seen as the extension of the notion of resonant frequencies for impenetrable objects to the case of penetrable dielectrics. The transmission eigenvalue problem is a relatively late arrival to the spectral theory of partial differential equations. Its first appearance was in 1986 in a paper by Kirsch who was investigating the denseness of far-field patterns for scattering solutions of the Helmholtz equation or, in more modern terminology, the injectivity of the far-field operator [1]. The paper of Kirsch was soon followed by a more systematic study by Colton and Monk in the context of developing the dual space method for solving the inverse scattering problem for acoustic waves in an inhomogeneous medium [2]. In this paper they showed that for a spherically stratified media transmission eigenvalues existed and formed a discrete set. Numerical examples were also given showing that in principle transmission eigenvalues could be determined from the far-field data. This first period of interest in transmission eigenvalues was concluded with papers by Colton et al in 1989 [3] and Rynne and Sleeman in 1991 [4] showing that for an inhomogeneous medium (not necessarily spherically stratified) transmission eigenvalues, if they existed, formed a discrete set. For the next seventeen years transmission eigenvalues were ignored. This was mainly due to the fact that, with the introduction of various sampling methods to determine the shape of an inhomogeneous medium from far-field data, transmission eigenvalues were something to be avoided and hence the fact that transmission eigenvalues formed at most a discrete set was deemed to be sufficient. In addition, questions related to the existence of transmission eigenvalues or the structure of associated eigenvectors were recognized as being particularly difficult due to the nonlinearity of the eigenvalue problem and the special structure of the associated transmission

  7. AQUIFER TRANSMISSIVITY

    EPA Science Inventory

    Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m2/sec) is a hydrauli...

  8. A novel CO 2 gas analyzer based on IR absorption

    NASA Astrophysics Data System (ADS)

    Zhang, Guangjun; Wu, Xiaoli

    2004-08-01

    Carbon dioxide (CO 2) gas analyzer can be widely used in many fields. A novel CO 2 gas analyzer based on infrared ray (IR) absorption is presented sufficiently in this paper. Applying Lambert-Beer Law, a novel space-double-beam optical structure is established successfully. The optical structure includes an IR source, a gas cell, a bandpass filter with a transmission wavelength at 4.26 μm, another bandpass filter with a transmission wavelength at 3.9 μm, and two IR detectors. Based on Redial Basic Function (RBF) artificial neural network, the measuring model of IR CO 2 analyzer is established with a high accuracy. A dynamic compensation filter is effectively designed to improve the dynamic characteristic of the IR CO 2 analyzer without gas pump. The IR CO 2 analyzer possesses the advantages of high accuracy and mechanical reliability with small volume, lightweight, and low-power consumption. Therefore, it can be used in such relevant fields as environmental protection, processing control, chemical analysis, medical diagnosis, and space environmental and control systems.

  9. Data on atmospheric transmission in the IR spectral region

    NASA Technical Reports Server (NTRS)

    Paramonova, N. N.; Kazakova, K. V.; Brounshteyn, A. M.

    1979-01-01

    The weakening of radiation by the atmosphere in the infrared region of the spectrum was studied. The instrument used for the measurements was the IKAU-1 infrared atmospheric unit, and measurements were carried out both on an inclined path and a near-earth horizontal path.

  10. Instrument measures many optical properties in visible and IR

    NASA Technical Reports Server (NTRS)

    Batten, C. E.

    1979-01-01

    Electro-optical system measures reflectance, reflectance ratio, transmission, absorption, refractive index, and absorption coefficient in both visible and infrared (IR) spectral regions. System effectively combining capabilities of ellisometer, reflectometer, and spectrophotometer is expected to find application in environmental and material composition testing fields.

  11. Study on antibacterial alginate-stabilized copper nanoparticles by FT-IR and 2D-IR correlation spectroscopy

    PubMed Central

    Díaz-Visurraga, Judith; Daza, Carla; Pozo, Claudio; Becerra, Abraham; von Plessing, Carlos; García, Apolinaria

    2012-01-01

    Background The objective of this study was to clarify the intermolecular interaction between antibacterial copper nanoparticles (Cu NPs) and sodium alginate (NaAlg) by Fourier transform infrared spectroscopy (FT-IR) and to process the spectra applying two-dimensional infrared (2D-IR) correlation analysis. To our knowledge, the addition of NaAlg as a stabilizer of copper nanoparticles has not been previously reported. It is expected that the obtained results will provide valuable additional information on: (1) the influence of reducing agent ratio on the formation of copper nanoparticles in order to design functional nanomaterials with increased antibacterial activity, and (2) structural changes related to the incorporation of Cu NPs into the polymer matrix. Methods Cu NPs were prepared by microwave heating using ascorbic acid as reducing agent and NaAlg as stabilizing agent. The characterization of synthesized Cu NPs by ultraviolet visible spectroscopy, transmission electron microscopy (TEM), electron diffraction analysis, X-ray diffraction (XRD), and semiquantitative analysis of the weight percentage composition indicated that the average particle sizes of Cu NPs are about 3–10 nm, they are spherical in shape, and consist of zerovalent Cu and Cu2O. Also, crystallite size and relative particle size of stabilized Cu NPs were calculated by XRD using Scherrer’s formula and FT from the X-ray diffraction data. Thermogravimetric analysis, differential thermal analysis, differential scanning calorimetry (DSC), FT-IR, second-derivative spectra, and 2D-IR correlation analysis were applied to studying the stabilization mechanism of Cu NPs by NaAlg molecules. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of stabilized Cu NPs against five bacterial strains (Staphylococccus aureus ATCC 6538P, Escherichia coli ATCC 25922 and O157: H7, and Salmonella enterica serovar Typhimurium ATCC 13311 and 14028) were evaluated with macrodilution

  12. IR Spot Weld Inspect

    SciTech Connect

    Chen, Jian; Feng, Zhili

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, data analysis, weld quality database generation and weld quality prediction, etc.

  13. IR Spot Weld Inspect

    Energy Science and Technology Software Center (ESTSC)

    2014-01-01

    In automotive industry, destructive inspection of spot welds is still the mandatory quality assurance method due to the lack of efficient non-destructive evaluation (NDE) tools. However, it is costly and time-consuming. Recently at ORNL, a new NDE prototype system for spot weld inspection using infrared (IR) thermography has been developed to address this problem. This software contains all the key functions that ensure the NDE system to work properly: system input/output control, image acquisition, datamore » analysis, weld quality database generation and weld quality prediction, etc.« less

  14. Multipath analysis diffraction calculations

    NASA Technical Reports Server (NTRS)

    Statham, Richard B.

    1996-01-01

    This report describes extensions of the Kirchhoff diffraction equation to higher edge terms and discusses their suitability to model diffraction multipath effects of a small satellite structure. When receiving signals, at a satellite, from the Global Positioning System (GPS), reflected signals from the satellite structure result in multipath errors in the determination of the satellite position. Multipath error can be caused by diffraction of the reflected signals and a method of calculating this diffraction is required when using a facet model of the satellite. Several aspects of the Kirchhoff equation are discussed and numerical examples, in the near and far fields, are shown. The vector form of the extended Kirchhoff equation, by adding the Larmor-Tedone and Kottler edge terms, is given as a mathematical model in an appendix. The Kirchhoff equation was investigated as being easily implemented and of good accuracy in the basic form, especially in phase determination. The basic Kirchhoff can be extended for higher accuracy if desired. A brief discussion of the method of moments and the geometric theory of diffraction is included, but seems to offer no clear advantage in implementation over the Kirchhoff for facet models.

  15. Resonant diffraction gratings for spatial differentiation of optical beams

    SciTech Connect

    Golovastikov, N V; Bykov, D A; Doskolovich, L L

    2014-10-31

    Diffraction of a two-dimensional optical beam from a resonant diffraction grating is considered. It is shown that at certain resonance parameters the diffraction grating allows for spatial differentiation and integration of the incident beam. The parameters of the diffraction grating for spatial differentiation of optical beams in the transmission geometry are calculated. It is shown that the differentiating diffraction grating allows the conversion of the two-dimensional beam into the two-dimensional Hermite – Gaussian mode. The presented results of numerical modelling are in good agreement with the proposed theoretical description. The use of the considered resonant diffraction gratings is promising for solving the problems of all-optical data processing. (laser applications and other topics in quantum electronics)

  16. Diffraction radiation generators

    NASA Astrophysics Data System (ADS)

    Shestopalov, Viktor P.; Vertii, Aleksei A.; Ermak, Gennadii P.; Skrynnik, Boris K.; Khlopov, Grigorii I.; Tsvyk, Aleksei I.

    Research in the field of diffraction radiation generators (DRG) conducted at the Radio Physics and electronics Institute of the Ukranian Academy of Sciences over the past 25 years is reviewed. The effect of diffraction radiation is analyzed in detail, and various operating regimes of DRGs are discussed. The discussion then focuses on the principal requirements for the design of packaged DRGs and their principal parameters. Finally, applications of DRGs in various fields of science and technology are reviewed, including such applications as DRG spectroscopy, diagnostics of plasma, biological specimens, and vibration, and DRG radar systems.

  17. Structure and Properties of Ir-Containing Oxides with Large Spin-Orbit Coupling: Ba2In(2-x)Ir(x)O(5+δ).

    PubMed

    Flynn, Joshua; Li, Jun; Sleight, Arthur W; Ramirez, Arthur P; Subramanian, M A

    2016-03-21

    In this work, the solid solution series Ba2In(2-x)Ir(x)O5+δ (x = 0-1.4, 2) was synthesized, and its structural, magnetic, and charge-transport properties were measured. With increasing Ir content, three transitions in the room-temperature structure were observed: orthorhombic to tetragonal to cubic to a monoclinic distortion of a hexagonal BaTiO3 structure. Neutron diffraction shows Ba2In(1.6)Ir(0.4)O5.4 to be cubic and Ba2InIrO6 to be monoclinic, the latter contrary to previously published X-ray diffraction refinements. Magnetization measurements show Curie-Weiss behavior for x = 0.2-0.6, which arises from nearly 50:50 ratio of Ir(V) and Ir(VI). To our knowledge, this is the first time Ir(VI) has been stabilized with standard solid-state methods under ambient conditions. The electrical resistivity measurements show all the compounds studied are semiconducting and that resistivity decreases with increasing Ir content, suggesting the proximity to a metal-insulator transition. A sign reversal in the high-temperature Seebeck coefficient is observed indicating both electron and hole charge transport. PMID:26937777

  18. Reflection and Transmission Coefficient of Yttrium Iron Garnet Filled Polyvinylidene Fluoride Composite Using Rectangular Waveguide at Microwave Frequencies

    PubMed Central

    Soleimani, Hassan; Abbas, Zulkifly; Yahya, Noorhana; Shameli, Kamyar; Soleimani, Hojjatollah; Shabanzadeh, Parvaneh

    2012-01-01

    The sol-gel method was carried out to synthesize nanosized Yttrium Iron Garnet (YIG). The nanomaterials with ferrite structure were heat-treated at different temperatures from 500 to 1000 °C. The phase identification, morphology and functional groups of the prepared samples were characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR), respectively. The YIG ferrite nanopowder was composited with polyvinylidene fluoride (PVDF) by a solution casting method. The magnitudes of reflection and transmission coefficients of PVDF/YIG containing 6, 10 and 13% YIG, respectively, were measured using rectangular waveguide in conjunction with a microwave vector network analyzer (VNA) in X-band frequencies. The results indicate that the presence of YIG in polymer composites causes an increase in reflection coefficient and decrease in transmission coefficient of the polymer. PMID:22942718

  19. Multiplexed off-axis holography using a transmission diffraction grating.

    PubMed

    Lu, Yujie; Liu, Yunhui; Li, Peng; Fu, Yili; Zhao, Jie

    2016-02-01

    This Letter presents a novel multiplexed off-axis holographic microscope that makes use of a 1D holographic grating. The grating creates multiple object waves and projects four of them to the imaging sensor. The object waves then interfere with the reference wave at the imaging sensor, so that a multiplexed hologram is created. This approach retrieves the amplitude and phase profiles of four imaging areas with a single-exposure hologram, which greatly increases the field of view of an off-axis holographic microscope. The experimental results with the resolution target USAF 1951 T-22 and a slide of paramecia are shown to demonstrate the system's ability without sacrificing the resolution of the microscope objective. PMID:26907411

  20. DIFFRACTION FROM MODEL CRYSTALS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although calculating X-ray diffraction patterns from atomic coordinates of a crystal structure is a widely available capability, calculation from non-periodic arrays of atoms has not been widely applied to cellulose. Non-periodic arrays result from modeling studies that, even though started with at...

  1. Diffractive hard scattering

    SciTech Connect

    Berger, E.L.; Collins, J.C.; Soper, D.E.; Sterman, G.

    1986-03-01

    I discuss events in high energy hadron collisions that contain a hard scattering, in the sense that very heavy quarks or high P/sub T/ jets are produced, yet are diffractive, in the sense that one of the incident hadrons is scattered with only a small energy loss. 8 refs.

  2. Integrated IR sensors

    NASA Astrophysics Data System (ADS)

    Tom, Michael; Trujillo, Edward

    1994-06-01

    Integrated infrared (IR) sensors which exploit modular avionics concepts can provide features such as operational flexibility, enhanced stealthiness, and ease of maintenance to meet the demands of tactical, airborne sensor systems. On-board, tactical airborne sensor systems perform target acquisition, tracking, identification, threat warning, missile launch detection, and ground mapping in support of situation awareness, self-defense, navigation, target attack, weapon support, and reconnaissance activities. The use of sensor suites for future tactical aircraft such as US Air Force's multirole fighter require a blend of sensor inputs and outputs that may vary over time. It is expected that special-role units of these tactical aircraft will be formed to conduct tasks and missions such as anti-shipping, reconnaissance, or suppression of enemy air defenses.

  3. Streaking images that appear only in the plane of diffraction in undoped GaAs single crystals: Diffraction imaging (topography) by monochromatic synchrotron radiation

    NASA Technical Reports Server (NTRS)

    Kuriyama, Masao; Steiner, Bruce; Dobbyn, Ronald C.; Laor, Uri; Larson, David; Brown, Margaret

    1988-01-01

    Streaking images restricted to the direction of the diffraction (scattering) vector have been observed on transmission through undoped GaAs. These disruption images (caused by the reduction of diffraction in the direction of observation) appear both in the forward and in Bragg diffracted directions in monochromatic synchrontron radiation diffraction imaging. This previously unobserved phenomenon can be explained in terms of planar defects (interfaces) or platelets which affects the absorption coefficient in anomalous transmission. Such regions of the crystal look perfect despite the presence of imperfections when the scattering vector is not perpendicular to the normal of the platelets. The observed crystallographic orientation of these interfaces strongly indicates that they are antiphase boundaries.

  4. Diffractive interference optical analyzer (DiOPTER)

    NASA Astrophysics Data System (ADS)

    Sasikumar, Harish; Prasad, Vishnu; Pal, Parama; Varma, Manoj M.

    2016-03-01

    This report demonstrates a method for high-resolution refractometric measurements using, what we have termed as, a Diffractive Interference Optical Analyzer (DiOpter). The setup consists of a laser, polarizer, a transparent diffraction grating and Si-photodetectors. The sensor is based on the differential response of diffracted orders to bulk refractive index changes. In these setups, the differential read-out of the diffracted orders suppresses signal drifts and enables time-resolved determination of refractive index changes in the sample cell. A remarkable feature of this device is that under appropriate conditions, the measurement sensitivity of the sensor can be enhanced by more than two orders of magnitude due to interference between multiply reflected diffracted orders. A noise-equivalent limit of detection (LoD) of 6x10-7 RIU was achieved in glass. This work focuses on devices with integrated sample well, made on low-cost PDMS. As the detection methodology is experimentally straightforward, it can be used across a wide array of applications, ranging from detecting changes in surface adsorbates via binding reactions to estimating refractive index (and hence concentration) variations in bulk samples. An exciting prospect of this technique is the potential integration of this device to smartphones using a simple interface based on transmission mode configuration. In a transmission configuration, we were able to achieve an LoD of 4x10-4 RIU which is sufficient to explore several applications in food quality testing and related fields. We are envisioning the future of this platform as a personal handheld optical analyzer for applications ranging from environmental sensing to healthcare and quality testing of food products.

  5. Development of a spin polarized low energy electron diffraction system.

    PubMed

    Pradeep, A V; Roy, Arnab; Kumar, P S Anil; Kirschner, J

    2016-02-01

    We have designed and constructed a spin polarized low energy electron diffraction system working in the reflected electron pulse counting mode. This system is capable of measuring asymmetries due to spin-orbit and exchange interactions. Photoemission from a strained GaAs/GaAsP super lattice is used as the source of spin polarized electrons. Spin-orbit asymmetry is evaluated for Ir(100) single crystal at various energies. Subsequently, exchange asymmetry has been evaluated on 40 monolayer Fe deposited on Ir(100). This instrument proves to be useful in understanding structure and magnetism at surfaces. PMID:26931865

  6. Development of a spin polarized low energy electron diffraction system

    NASA Astrophysics Data System (ADS)

    Pradeep, A. V.; Roy, Arnab; Kumar, P. S. Anil; Kirschner, J.

    2016-02-01

    We have designed and constructed a spin polarized low energy electron diffraction system working in the reflected electron pulse counting mode. This system is capable of measuring asymmetries due to spin-orbit and exchange interactions. Photoemission from a strained GaAs/GaAsP super lattice is used as the source of spin polarized electrons. Spin-orbit asymmetry is evaluated for Ir(100) single crystal at various energies. Subsequently, exchange asymmetry has been evaluated on 40 monolayer Fe deposited on Ir(100). This instrument proves to be useful in understanding structure and magnetism at surfaces.

  7. Magnetic polarization of Ir in underdoped nonsuperconducting Eu(Fe 0.94Ir0.06)2As2

    NASA Astrophysics Data System (ADS)

    Jin, W. T.; Xiao, Y.; Su, Y.; Nandi, S.; Jiao, W. H.; Nisbet, G.; Demirdis, S.; Cao, G. H.; Brückel, Th.

    2016-01-01

    Using polarized neutron diffraction and x-ray resonant magnetic scattering (XRMS) techniques, multiple phase transitions were revealed in an underdoped, nonsuperconducting Eu (Fe1 -xIrx )2As2 (x =0.06 ) single crystal. Compared with the parent compound EuFe2As2 , the tetragonal-to-orthorhombic structural phase transition and the antiferromagnetic order of the Fe+2 moments are significantly suppressed to TS=111 (2 ) K and TN,Fe=85 (2 ) K by 6% Ir doping, respectively. In addition, the Eu+2 spins order within the a b plane in the A-type antiferromagnetic structure similar to the parent compound. However, the order temperature is evidently suppressed to TN,Eu=16.0 (5 ) K by Ir doping. Most strikingly, the XRMS measurements at the Ir L3 edge demonstrates that the Ir 5 d states are also magnetically polarized, with the same propagation vector as the magnetic order of Fe. With TN,Ir=12.0 (5 ) K, they feature a much lower onset temperature compared with TN,Fe. Our observation suggests that the magnetism of the Eu sublattice has a considerable effect on the magnetic nature of the 5 d Ir dopant atoms and there exists a possible interplay between the localized Eu+2 moments and the conduction d electrons on the FeAs layers.

  8. Transmissible amyloid.

    PubMed

    Tjernberg, L O; Rising, A; Johansson, J; Jaudzems, K; Westermark, P

    2016-08-01

    There are around 30 human diseases associated with protein misfolding and amyloid formation, each one caused by a certain protein or peptide. Many of these diseases are lethal and together they pose an enormous burden to society. The prion protein has attracted particular interest as being shown to be the pathogenic agent in transmissible diseases such as kuru, Creutzfeldt-Jakob disease and bovine spongiform encephalopathy. Whether similar transmission could occur also in other amyloidoses such as Alzheimer's disease, Parkinson's disease and serum amyloid A amyloidosis is a matter of intense research and debate. Furthermore, it has been suggested that novel biomaterials such as artificial spider silk are potentially amyloidogenic. Here, we provide a brief introduction to amyloid, prions and other proteins involved in amyloid disease and review recent evidence for their potential transmission. We discuss the similarities and differences between amyloid and silk, as well as the potential hazards associated with protein-based biomaterials. PMID:27002185

  9. Rotorcraft transmissions

    NASA Technical Reports Server (NTRS)

    Coy, John J.

    1990-01-01

    Highlighted here is that portion of the Lewis Research Center's helicopter propulsion systems program that deals with drive train technology and the related mechanical components. The major goals of the program are to increase life, reliability, and maintainability, to reduce weight, noise, and vibration, and to maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development, followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented.

  10. Electronic signatures of dimerization in IrTe2

    NASA Astrophysics Data System (ADS)

    Dai, Jixia; Wu, Weida; Oh, Yoon Seok; Cheong, S.-W.; Yang, J. J.

    2014-03-01

    Recently, the mysterious phase transition around Tc ~ 260 K in IrTe2 has been intensively studied. A structural supermodulation with q =1/5 was identified below Tc. A variety of microscopic mechanisms have been proposed to account for this transition, including charge-density wave due to Fermi surface nesting, Te p-orbital driven structure instability, anionic depolymerization, ionic dimerization, and so on. However, there has not been an unified picture on the nature of this transition. To address this issue, we have performed low-temperature scanning tunneling microscopy and spectroscopy (STM/STS) experiments on IrTe2 and IrTe2-xSex. Our STM data clearly shows a strong bias dependence in both topography and local density of states (STS) maps. High resolution spectroscopic data further confirms the stripe-like electronic states modulation, which provides insight to the ionic dimerization revealed by X-ray diffraction.

  11. Colored Diffraction Catastrophes

    NASA Astrophysics Data System (ADS)

    Berry, M. V.; Klein, S.

    1996-03-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences.

  12. Central diffraction at ALICE

    NASA Astrophysics Data System (ADS)

    Lämsä, J. W.; Orava, R.

    2011-02-01

    The ALICE experiment is shown to be well suited for studies of exclusive final states from central diffractive reactions. The gluon-rich environment of the central system allows detailed QCD studies and searches for exotic meson states, such as glueballs, hybrids and new charmonium-like states. It would also provide a good testing ground for detailed studies of heavy quarkonia. Due to its central barrel performance, ALICE can accurately measure the low-mass central systems with good purity. The efficiency of the Forward Multiplicity Detector (FMD) and the Forward Shower Counter (FSC) system for detecting rapidity gaps is shown to be adequate for the proposed studies. With this detector arrangement, valuable new data can be obtained by tagging central diffractive processes.

  13. Colored diffraction catastrophes.

    PubMed Central

    Berry, M V; Klein, S

    1996-01-01

    On fine scales, caustics produced with white light show vividly colored diffraction fringes. For caustics described by the elementary catastrophes of singularity theory, the colors are characteristic of the type of singularity. We study the diffraction colors of the fold and cusp catastrophes. The colors can be simulated computationally as the superposition of monochromatic patterns for different wavelengths. Far from the caustic, where the luminosity contrast is negligible, the fringe colors persist; an asymptotic theory explains why. Experiments with caustics produced by refraction through irregular bathroom-window glass show good agreement with theory. Colored fringes near the cusp reveal fine lines that are not present in any of the monochromatic components; these lines are explained in terms of partial decoherence between rays with widely differing path differences. Images Fig. 1 Fig. 2 Fig. 3 Fig. 6 Fig. 8 Fig. 9 Fig. 10 PMID:11607642

  14. Nonreciprocal optical diffraction by a single layer of gyromagnetic cylinders.

    PubMed

    Guo, Tian-Jing; Li, Teng-Fei; Yang, Mu; Cui, Hai-Xu; Guo, Qing-Hua; Cao, Xue-Wei; Chen, Jing

    2014-01-13

    We study the diffraction of optical waves by a single layer of gyromagnetic cylinders. We show that a nonvanishing rotating dipole momentum is excited in a single gyromagnetic cylinder because of the classic analog of the Zeeman effect on photonic angular momentum states (PAMSs). Consequently, different collective dipole modes are excited in a gyromagnetic cylinder array at opposite incident angles. Nonreciprocal optical diffraction effects can be observed, where the transmission and reflection coefficients depend on the sign of the incident angle. A novel phenomenon of nonreciprocal negative directional transmission is demonstrated and numerically analyzed. This work highlights the potential of PAMSs in manipulating the propagation of optical waves for various applications. PMID:24515014

  15. Diffraction before destruction

    PubMed Central

    Chapman, Henry N.; Caleman, Carl; Timneanu, Nicusor

    2014-01-01

    X-ray free-electron lasers have opened up the possibility of structure determination of protein crystals at room temperature, free of radiation damage. The femtosecond-duration pulses of these sources enable diffraction signals to be collected from samples at doses of 1000 MGy or higher. The sample is vaporized by the intense pulse, but not before the scattering that gives rise to the diffraction pattern takes place. Consequently, only a single flash diffraction pattern can be recorded from a crystal, giving rise to the method of serial crystallography where tens of thousands of patterns are collected from individual crystals that flow across the beam and the patterns are indexed and aggregated into a set of structure factors. The high-dose tolerance and the many-crystal averaging approach allow data to be collected from much smaller crystals than have been examined at synchrotron radiation facilities, even from radiation-sensitive samples. Here, we review the interaction of intense femtosecond X-ray pulses with materials and discuss the implications for structure determination. We identify various dose regimes and conclude that the strongest achievable signals for a given sample are attained at the highest possible dose rates, from highest possible pulse intensities. PMID:24914146

  16. Polychromatic diffraction contrast tomography

    SciTech Connect

    King, A.; Reischig, P.; Adrien, J.; Peetermans, S.; Ludwig, W.

    2014-11-15

    This tutorial review introduces the use of polychromatic radiation for 3D grain mapping using X-ray diffraction contrast tomography. The objective is to produce a 3D map of the grain shapes and orientations within a bulk, millimeter-sized polycrystalline sample. The use of polychromatic radiation enables the standard synchrotron X-ray technique to be applied in a wider range of contexts: 1) Using laboratory X-ray sources allows a much wider application of the diffraction contrast tomography technique. 2) Neutron sources allow large samples, or samples containing high Z elements to be studied. 3) Applied to synchrotron sources, smaller samples may be treated, or faster measurements may be possible. Challenges and particularities in the data acquisition and processing, and the limitations of the different variants, are discussed. - Highlights: • We present a tutorial review of polychromatic diffraction contrast tomography techniques. • The use of polychromatic radiation allows the standard synchrotron DCT technique to be extended to a range of other sources. • The characteristics and limitations of all variants of the techniques are derived, discussed and compared. • Examples using laboratory X-ray and cold neutron radiation are presented. • Suggestions for the future development of these techniques are presented.

  17. IR Stray Light

    NASA Astrophysics Data System (ADS)

    Petro, Larry

    2009-07-01

    Structures outside the optical path of the detector FOV and the surfaces of optical elements could scatter significant light from bright sources onto the IR FPA. Such structures are oversized by typically a few mm relative to the FOV?s beam. The beam footprint of a source outside the FOV can overlap the edges of those structures, which will cause light to be scattered onto the detector. During ground test, it was found that one per cent of the signal from a target imaged onto the edge of the detector was scattered into an approximately 10 pixel by 100 pixel flare. This on orbit test will: 1} verify that release of gravitational stress has not changed the detector mask, 2} assess the far wing stray light from a sources outside the detector FOV, 3} note any sources of stray light in the near and far field that were not noted during ground test, and 4} assess the surface brightness of the off-detector target PSF relative to the on-detector PSF

  18. Perpendicular exchange bias behaviors of CoPt/IrMn and CoPt/FeMn bilayers: A comparative study

    SciTech Connect

    Tsai, C. Y.; Lin, K. F.; Hsu, Jen-Hwa

    2015-05-07

    In this study, FeMn was introduced as an antiferromagnetic (AFM) layer to couple with a single-layered Co{sub 49}Pt{sub 51} alloy thin film, and it was compared with a Co{sub 49}Pt{sub 51}/IrMn bilayer system in exchange bias (EB) effect, to explore the mechanism of spontaneous perpendicular exchange bias (PEB), which has been recently observed in CoPt/IrMn bilayers. Bilayers of CoPt/IrMn and CoPt/FeMn were prepared under the same conditions by sputtering at room temperature without any inducing field. Although PEB was observed in as-grown CoPt/FeMn bilayers, the loop shape and PEB behavior were found to exhibit different characteristics from those of CoPt/IrMn bilayers. The CoPt (5 nm)/FeMn (10 nm) bilayer has a sheared loop that is similar to a double-shifted loop and a much lower squareness ratio (SQR = 0.52) and exchange bias field (H{sub e} = 180 Oe) than the CoPt (5 nm)/IrMn (10 nm) system, which has a rectangular loop shape and a high SQR of 0.97 and large H{sub e} of 290 Oe. The two systems present entirely different dependences of PEB on the thickness of the AFM layer. CoPt/IrMn exhibits behavior that is typical of most EB systems, but for CoPt/FeMn, this dependence is more complicated with an unusual peak at an AFM layer thickness of 10 nm. Based on the dissimilar loop shapes and dependences of PEB on AFM thickness, the mechanisms of the spontaneously established PEB in these two systems are considered to differ. Investigations of cross-sectional transmission electron microscopy revealed no apparent difference between the interfacial microstructures of the two systems. X-ray diffraction studies demonstrated the 〈111〉 texture of both systems. Therefore, different interfacial spin configurations may be responsible for the dissimilar PEB behaviors in these two FM/AFM bilayer systems.

  19. Fabrication of high-efficiency diffraction gratings in glass

    NASA Astrophysics Data System (ADS)

    Takeshima, Nobuhito; Narita, Yoshihiro; Tanaka, Shuhei; Kuroiwa, Yutaka; Hirao, Kazuyuki

    2005-02-01

    We investigated a microfabrication process for optical gratings with periods of micrometer order that use ultrafast laser pulses in semiconductor-doped glass. ZnS- or PbS-doped SiO2 - Al2O3 - B2O3 - CaO - ZnO - Na2O - K2O glass was prepared by a melting method. Glass transmission diffraction gratings with a high refractive-index difference were fabricated with femtosecond laser pulses. The first-order diffraction efficiencies of these gratings were approximately 80%, and the first-order diffraction angles of these gratings were 8° at telecommunication wavelengths.

  20. Investigation of Acrylic Acid at High Pressure Using Neutron Diffraction

    PubMed Central

    2014-01-01

    This article details the exploration of perdeuterated acrylic acid at high pressure using neutron diffraction. The structural changes that occur in acrylic acid-d4 are followed via diffraction and rationalized using the Pixel method. Acrylic acid undergoes a reconstructive phase transition to a new phase at ∼0.8 GPa and remains molecular to 7.2 GPa before polymerizing on decompression to ambient pressure. The resulting product is analyzed via Raman and FT-IR spectroscopy and differential scanning calorimetry and found to possess a different molecular structure compared with polymers produced via traditional routes. PMID:24650085

  1. Magnetism and electronic structure of La2ZnIrO6 and La2MgIrO6: Candidate Jeff=(1)/(2) Mott insulators

    NASA Astrophysics Data System (ADS)

    Cao, Guixin; Subedi, Alaska; Calder, S.; Yan, J.-Q.; Yi, Jieyu; Gai, Zheng; Poudel, Lekhanath; Singh, David J.; Lumsden, Mark D.; Christianson, A. D.; Sales, Brian C.; Mandrus, David

    2013-04-01

    We study experimentally and theoretically the electronic and magnetic properties of two insulating double perovskites that show similar atomic and electronic structure but different magnetic properties. In magnetization measurements, La2ZnIrO6 displays weak ferromagnetic behavior below 7.5 K, whereas La2MgIrO6 shows antiferromagnetic behavior below TN = 12 K. Electronic structure calculations find that the weak ferromagnetic behavior observed in La2ZnIrO6 is in fact due to canted antiferromagnetism. The calculations also predict canted antiferromagnetic behavior in La2MgIrO6, but intriguingly, this was not observed. Neutron diffraction measurements confirm the essentially antiferromagnetic behavior of both systems but lack the sensitivity to resolve the small (0.22μB/Ir) ferromagnetic component in La2ZnIrO6. Overall, the results presented here indicate the crucial role of spin-orbit coupling (SOC) and the on-site Coulomb repulsion on the magnetic, transport, and thermodynamic properties of both compounds. The electronic structure calculations show that both compounds, like Sr2IrO4, are Jeff = 1/2 Mott insulators. Our present findings suggest that La2ZnIrO6 and La2MgIrO6 provide a new playground to study the interplay between SOC and on-site Coulomb repulsion in a 5d transition-metal oxide.

  2. Eyeglass: A Very Large Aperture Diffractive Space Telescope

    SciTech Connect

    Hyde, R; Dixit, S; Weisberg, A; Rushford, M

    2002-07-29

    Eyeglass is a very large aperture (25-100 meter) space telescope consisting of two distinct spacecraft, separated in space by several kilometers. A diffractive lens provides the telescope's large aperture, and a separate, much smaller, space telescope serves as its mobile eyepiece. Use of a transmissive diffractive lens solves two basic problems associated with very large aperture space telescopes; it is inherently fieldable (lightweight and flat, hence packagable and deployable) and virtually eliminates the traditional, very tight, surface shape tolerances faced by reflecting apertures. The potential drawback to use of a diffractive primary (very narrow spectral bandwidth) is eliminated by corrective optics in the telescope's eyepiece. The Eyeglass can provide diffraction-limited imaging with either single-band, multiband, or continuous spectral coverage. Broadband diffractive telescopes have been built at LLNL and have demonstrated diffraction-limited performance over a 40% spectral bandwidth (0.48-0.72 {micro}m). As one approach to package a large aperture for launch, a foldable lens has been built and demonstrated. A 75 cm aperture diffractive lens was constructed from 6 panels of 1 m thick silica; it achieved diffraction-limited performance both before and after folding. This multiple panel, folding lens, approach is currently being scaled-up at LLNL. We are building a 5 meter aperture foldable lens, involving 72 panels of 700 {micro}m thick glass sheets, diffractively patterned to operate as coherent f/50 lens.

  3. Structural study by X-ray diffraction and transmission electron microscopy of the misfit compound (SbS{sub 1-x}Se{sub x}){sub 1.16}(Nb{sub 1.036}S{sub 2}){sub 2}

    SciTech Connect

    Kars, Mohammed; Fredrickson, Daniel C.; Gomez-Herrero, A.; Lidin, Sven; Rebbah, Allaoua; Otero-Diaz, L.C.; Dpto. Inorganica, Fac. C.C. Quimicas, Universidad Complutense, 28040 Madrid

    2010-08-15

    In the Sb-Nb-S-Se system, a new misfit layer compound (MSL) has been synthesized and its structure was determined by combining single crystal X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. It presents a composite crystal structure formed by (SbS{sub 1-x}Se{sub x}) slabs stacking alternately with double NbS{sub 2} layers and both can be treated as separate monoclinic subsystems. The (SbS{sub 1-x}Se{sub x}) slabs comprise a distorted, two-atom-thick layer with NaCl-type structure formed by an array of {l_brace}SbX{sub 5}{r_brace} square pyramids joined by edges (X: S, Se); the NbS{sub 2} layers consist of {l_brace}NbS{sub 6}{r_brace} trigonal prisms linked through edge-sharing to form sheets, just as in the 2H-NbS{sub 2} structure type. Both sublattices have the same lattice parameters a = 5.7672(19) A, c = 17.618(6) A and {beta} = 96.18(3){sup o}, with incommensurability occurring along the b direction: b{sub 1} = 3.3442(13) A for the NbS{sub 2} subsystem and b{sub 2} = 2.8755(13) A for the (SbS{sub 1-x}Se{sub x}) subsystem. The occurrence of diffuse scattering intensity streaked along c{sup *} indicates that the (SbS{sub 1-x}Se{sub x}) subsystem is subjected to extended defects along the stacking direction.

  4. Visible/near-IR-light-driven TNFePc/BiOCl organic-inorganic heterostructures with enhanced photocatalytic activity.

    PubMed

    Li, Lu; Zhang, Mingyi; Zhao, Zhenyu; Sun, Baodong; Zhang, Xitian

    2016-06-21

    Although semiconductor photocatalysis has been reported for more than 40 years, the spectral response is still focused on the region of UV-Visible and it is seldom extended to more than 600 nm. In this work, visible/near-IR-light-driven 2,9,16,23-tetranitrophthalocyanine iron (FeTNPc)/bismuth oxychloride (BiOCl) organic-inorganic heterostructures have been synthesized by a two-step solvothermal method. The obtained products were characterized by X-ray diffraction, Fourier transform infrared spectra, scanning electron and transmission microscopy, energy dispersive X-ray spectrometer, UV-vis diffuse reflectance spectroscopy, nitrogen adsorption-desorption, and electrochemical measurements. The photocatalytic activity for the decomposition of methyl orange and bisphenol A solution can be significantly improved under visible/near-IR-light irradiation. Through detecting the main oxidative species by trapping experiments, the results show holes and ˙O2(-) radicals are majorly and minorly responsible for photodegradation respectively. What's more, the FeTNPc/BiOCl composite photocatalyst still retained the photocatalytic activity after three cycle measurements. PMID:27192122

  5. Synthesis, characterization of (3E)-1-(6-chloro-2-methyl-4-phenyl quinolin-3-Yl)-3-aryl prop-2-en-1-ones through IR, NMR, single crystal X-ray diffraction and insights into their electronic structure using DFT calculations

    NASA Astrophysics Data System (ADS)

    Sarveswari, S.; Srikanth, A.; Arul Murugan, N.; Vijayakumar, V.; Jasinski, Jerry P.; Beauchesne, Hanna C.; Jarvis, Ethan E.

    2015-02-01

    3E-1-(6-Chloro-2-methyl-4-phenylquinolin-3-yl)-3-arylprop-2-en-1-ones were synthesized and characterized by FTIR, 1H NMR, 13C NMR, HSQC, DEPT-135. In addition the compound 3E-1-(6-chloro-2-methyl-4-phenylquinolin-3-yl)-3-(2,5-dimethoxyphenyl)prop-2-en-1-one was subjected to the single crystal X-ray diffraction studies. Density functional theory calculations were carried out for this chalcone and its derivatives to investigate into their electronic structure, chemical reactivity, linear and non-linear optical properties. The structure predicted from DFT for chalcone is in good agreement with the structure from XRD measurement.

  6. Diffraction of a Laser Beam.

    ERIC Educational Resources Information Center

    Jodoin, Ronald E.

    1979-01-01

    Investigates the effect of the nonuniform irradiance across a laser beam on diffraction of the beam, specifically the Fraunhofer diffraction of a laser beam with a Gaussian irradiance profile as it passes through a circular aperture. (GA)

  7. Rotorcraft transmission

    NASA Technical Reports Server (NTRS)

    Coy, John J.

    1987-01-01

    The NASA Lewis Research Center and the U.S. Army Aviation Systems Command share an interest in advancing the technology for helicopter propulsion systems. In particular, this presentation outlines that portion of the program that applies to the drive train and its various mechanical components. The major goals of the program are to increase the life, reliability, and maintainability; reduce the weight, noise, and vibration; and maintain the relatively high mechanical efficiency of the gear train. The current activity emphasizes noise reduction technology and analytical code development followed by experimental verification. Selected significant advances in technology for transmissions are reviewed, including advanced configurations and new analytical tools. Finally, the plan for transmission research in the future is presented.

  8. Aberrations of diffracted wave fields. II. Diffraction gratings.

    PubMed

    Mahajan, V N

    2000-12-01

    The Rayleigh-Sommerfeld theory is applied to diffraction of a spherical wave by a grating. The grating equation is obtained from the aberration-free diffraction pattern, and its aberrations are shown to be the same as the conventional aberrations obtained by using Fermat's principle. These aberrations are shown to be not associated with the diffraction process. Moreover, it is shown that the irradiance distribution of a certain diffraction order is the Fraunhofer diffraction pattern of the grating aperture as a whole aberrated by the aberration of that order. PMID:11140481

  9. Recent diffractive results from HERA

    NASA Astrophysics Data System (ADS)

    Valkárová, Alice

    2016-07-01

    The diffractive dijet cross sections for photoproduction and deep inelastic scattering were studied and compared with theoretical NLO QCD predictions. The results of exclusive dijet production were compared to predictions from models which are based on different assumptions about the nature of diffractive exchange. Isolated prompt photons in diffractive photoproduction produced inclusively or together with a jet were studied for the first time.

  10. Spectral diffraction efficiency characterization of broadband diffractive optical elements.

    SciTech Connect

    Choi, Junoh; Cruz-Cabrera, Alvaro Augusto; Tanbakuchi, Anthony

    2013-03-01

    Diffractive optical elements, with their thin profile and unique dispersion properties, have been studied and utilized in a number of optical systems, often yielding smaller and lighter systems. Despite the interest in and study of diffractive elements, the application has been limited to narrow spectral bands. This is due to the etch depths, which are optimized for optical path differences of only a single wavelength, consequently leading to rapid decline in efficiency as the working wavelength shifts away from the design wavelength. Various broadband diffractive design methodologies have recently been developed that improve spectral diffraction efficiency and expand the working bandwidth of diffractive elements. We have developed diffraction efficiency models and utilized the models to design, fabricate, and test two such extended bandwidth diffractive designs.

  11. Variation in MidIR and LWIR polarimetric imagery due to diurnal and meteorological impacts

    NASA Astrophysics Data System (ADS)

    Gurton, Kristan P.; Felton, Melvin

    2008-04-01

    We present radiometric and polarimetric calibrated imagery recorded in both the mid-wave IR (MidIR) and long wave IR (LWIR) as a function diurnal variation over several multiday periods. We compare differences in polarimetric and conventional thermal imagry for both IR atmospheric transmission windows, i.e., 3-5μm and 8-12 μm regions. Meteorological parameters measured during the study include temperature, relative-humidity, wind-speed/direction, precipitation, and ambient atmospheric IR loading. The two camera systems used in the study differed significantly in design. The LWIR polarimetric sensor utilizes a spinning achromatic retarder and is best suited for static scenes, while the MidIR system is based on a division-of-aperture design and is capable of recording polarimetric imagery of targets that are rapidly moving. Examples of both S0 (conventional thermal) and degree-of-linear polarization (DOLP) imagery are presented and compared.

  12. Electronic excitations and structure of Li{sub 2}IrO{sub 3} thin films grown on ZrO{sub 2}:Y (001) substrates

    SciTech Connect

    Jenderka, Marcus Schmidt-Grund, Rüdiger; Grundmann, Marius; Lorenz, Michael

    2015-01-14

    Thin films are a prerequisite for application of the emergent exotic ground states in iridates that result from the interplay of strong spin-orbit coupling and electronic correlations. We report on pulsed laser deposition of Li{sub 2}IrO{sub 3} films on ZrO{sub 2}:Y (001) single crystalline substrates. X-ray diffraction confirms preferential (001) and (10-1) out-of-plane crystalline orientations with well defined in-plane orientation. Resistivity between 35 and 300 K is dominated by a three-dimensional variable range hopping mechanism. The dielectric function is determined by means of spectroscopic ellipsometry and, complemented by Fourier transform infrared transmission spectroscopy, reveals a small optical gap of ≈300 meV, a splitting of the 5d-t{sub 2g} manifold, and several in-gap excitations attributed to phonons and possibly magnons.

  13. Transmission electron microscope studies of extraterrestrial materials

    NASA Technical Reports Server (NTRS)

    Keller, Lindsay P.

    1995-01-01

    Transmission Electron Microscopy, X-Ray spectrometry and electron-energy-loss spectroscopy are used to analyse carbon in interplanetary dust particles. Optical micrographs are shown depicting cross sections of the dust particles embedded in sulphur. Selected-area electron diffraction patterns are shown. Transmission Electron Microscope specimens of lunar soil were prepared using two methods: ion-milling and ultramicrotomy. A combination of high resolution TEM imaging and electron diffraction is used to characterize the opaque assemblages. The opaque assemblages analyzed in this study are dominated by ilmenite with lesser rutile and spinel exsolutions, and traces of Fe metal.

  14. Optical/IR from ground

    NASA Technical Reports Server (NTRS)

    Strom, Stephen; Sargent, Wallace L. W.; Wolff, Sidney; Ahearn, Michael F.; Angel, J. Roger; Beckwith, Steven V. W.; Carney, Bruce W.; Conti, Peter S.; Edwards, Suzan; Grasdalen, Gary

    1991-01-01

    Optical/infrared (O/IR) astronomy in the 1990's is reviewed. The following subject areas are included: research environment; science opportunities; technical development of the 1980's and opportunities for the 1990's; and ground-based O/IR astronomy outside the U.S. Recommendations are presented for: (1) large scale programs (Priority 1: a coordinated program for large O/IR telescopes); (2) medium scale programs (Priority 1: a coordinated program for high angular resolution; Priority 2: a new generation of 4-m class telescopes); (3) small scale programs (Priority 1: near-IR and optical all-sky surveys; Priority 2: a National Astrometric Facility); and (4) infrastructure issues (develop, purchase, and distribute optical CCDs and infrared arrays; a program to support large optics technology; a new generation of large filled aperture telescopes; a program to archive and disseminate astronomical databases; and a program for training new instrumentalists)

  15. Hard diffraction in Pythia 8

    NASA Astrophysics Data System (ADS)

    Overgaard Rasmussen, Christine

    2016-07-01

    We present an overview of the options for diffraction implemented in the general-purpose event generator Pythia 8 [1]. We review the existing model for soft diffraction and present a new model for hard diffraction. Both models use the Pomeron approach pioneered by Ingelman and Schlein, factorising the diffractive cross section into a Pomeron flux and a Pomeron PDF, with several choices for both implemented in Pythia 8. The model of hard diffraction is implemented as a part of the multiparton interactions (MPI) framework, thus introducing a dynamical gap survival probability that explicitly breaks factorisation.

  16. Integrated uncooled array IR sensors

    NASA Astrophysics Data System (ADS)

    Pevtsov, Eugeny P.; Elkin, Eugeny G.; Pospelova, Marina A.

    1997-08-01

    Technologies enabling low-dissipation designs for uncooled array IR sensors are offered. The technique involves the etching of special buffer layers from under a 1-micrometers membrane followed by deposition of an IR-sensitive film and electrode structure. The electrical and physical properties of plumbum-zirconate-titanate, barium titanate, tetraaminodiphenyl, polyvinylidene fluoride pyroelectric films are compared. A circuit for sensing pyroelectric signals in a CCD is considered.

  17. Controlled tuning of thin film deposition of IrO2 on Si using pulsed laser ablation technique

    NASA Astrophysics Data System (ADS)

    Koshy, Abraham M.; Bhat, Shwetha G.; Kumar, P. S. Anil

    2016-05-01

    We have successfully grown a stable phase of polycrystalline IrO2 on Si (100) substrate. We have found that the phase of IrO2 can be controllably tuned to obtain either Ir or IrO2 using pulsed laser ablation technique. O2 conditions during the deposition influences the phase directly and drastically whereas annealing conditions do not show any variation in the phase of thin film. X-ray diffraction and X-ray photoemission experiments confirm both Ir and IrO2 can be successively grown on Si using IrO2 target. Also, the morphology is found to be influenced by the O2 conditions.

  18. Thulium fiber laser-pumped mid-IR OPO

    NASA Astrophysics Data System (ADS)

    Creeden, Daniel; Jiang, Min; Budni, Peter A.; Ketteridge, Peter A.; Setzler, Scott D.; Young, York E.; McCarthy, John C.; Schunemann, Peter G.; Pollak, Thomas M.; Tayebati, Parviz; Chicklis, Evan P.

    2008-04-01

    Fiber lasers are advancing rapidly due to their ability to generate stable, efficient, and diffraction-limited beams with significant peak and average powers. This is of particular interest as fibers provide an ideal pump source for driving parametric processes. Most nonlinear optical crystals which provide phase-matching to the mid-IR at commercially available fiber pump wavelengths suffer from high absorption above 4μm, resulting in low conversion efficiencies in the 4-5μm spectral region. The nonlinear optical crystals which combine low absorption in this same spectral region with high nonlinear gain require pumping at longer wavelengths (typically >1.9μm). In this paper, we report a novel mid-IR OPO pumped by a pulsed thulium-doped fiber laser operating at 2-microns. The eyesafe thulium-fiber pump laser generates >3W of average power at >30kHz repetition rate with 15-30ns pulses in a near diffraction-limited beam. The ZnGeP II (ZGP) OPO produces tunable mid-IR output power in the 3.4-3.99μm (signal) and the 4.0-4.7μm (idler) spectral regions in both singly resonant (SRO) and doubly resonant (DRO) formats. The highest mid-IR output power achieved from this system was 800mW with 20% conversion efficiency at 40kHz. In a separate experiment, the 3W of 2-micron light was further amplified to the 20W level. This amplified output was also used to pump a ZGP OPO, resulting in 2W of output power in the mid-IR. To our knowledge, these are the first demonstrations of a fiber-pumped ZGP OPO.

  19. Structured beam diffraction.

    PubMed

    Castagna, R; Di Donato, A; Nucara, L; Xu, J H; Lucchetta, D E; Simoni, F

    2016-04-01

    We report on the observation of a modulated pattern induced by a single laser beam in a polymeric film. In spite of the simple geometrical configuration, the analysis of the far field diffraction pattern allows a sensitive retrieving of the wavelength of the recording beam and of its incidence angle, pointing out the high information content of the recorded spot. A theoretical model is presented which satisfactorily explains the observed behavior. It takes into account the interaction of structured light with structured matter with the same symmetries and spatial modulation frequencies close to each other. This result shows a feature of the interaction between structured light and structured matter which has not been explored yet. PMID:27192262

  20. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, Gary E.

    1996-01-01

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of .lambda./1000 where .lambda. is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about .lambda./50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms.

  1. Phase shifting diffraction interferometer

    DOEpatents

    Sommargren, G.E.

    1996-08-29

    An interferometer which has the capability of measuring optical elements and systems with an accuracy of {lambda}/1000 where {lambda} is the wavelength of visible light. Whereas current interferometers employ a reference surface, which inherently limits the accuracy of the measurement to about {lambda}/50, this interferometer uses an essentially perfect spherical reference wavefront generated by the fundamental process of diffraction. This interferometer is adjustable to give unity fringe visibility, which maximizes the signal-to-noise, and has the means to introduce a controlled prescribed relative phase shift between the reference wavefront and the wavefront from the optics under test, which permits analysis of the interference fringe pattern using standard phase extraction algorithms. 8 figs.

  2. Multilayer diffraction grating

    DOEpatents

    Barbee, Jr., Troy W.

    1990-01-01

    This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages.

  3. Multilayer diffraction grating

    DOEpatents

    Barbee, T.W. Jr.

    1990-04-10

    This invention is for a reflection diffraction grating that functions at X-ray to VUV wavelengths and at normal angles of incidence. The novel grating is comprised of a laminar grating of period D with flat-topped grating bars. A multiplicity of layered synthetic microstructures, of period d and comprised of alternating flat layers of two different materials, are disposed on the tops of the grating bars of the laminar grating. In another embodiment of the grating, a second multiplicity of layered synthetic microstructures are also disposed on the flat faces, of the base of the grating, between the bars. D is in the approximate range from 3,000 to 50,000 Angstroms, but d is in the approximate range from 10 to 400 Angstroms. The laminar grating and the layered microstructures cooperatively interact to provide many novel and beneficial instrumentational advantages. 2 figs.

  4. Dichroic Coherent Diffractive Imaging

    NASA Astrophysics Data System (ADS)

    Tripathi, Ashish

    Understanding electronic structure at nanometer resolution is crucial to understanding physics such as phase separation and emergent behavior in correlated electron materials. Nondestructive probes which have the ability to see beyond surfaces on nanometer length and sub-picosecond time scales can greatly enhance our understanding of these systems and will impact development of future technologies, such as magnetic storage. Polarized x-rays are an appealing choice of probe due to their penetrating power, elemental and magnetic specificity, and high spatial resolution. The resolution of traditional x-ray microscopy is limited by the nanometer precision required to fabricate x-ray optics. In this thesis, a novel approach to lensless imaging of an extended magnetic nanostructure is presented. We demonstrate this approach by imaging ferrimagnetic "maze" domains in a Gd/Fe multilayer with perpendicular anisotropy. A series of dichroic coherent diffraction patterns, ptychographically recorded, are numerically inverted using non-convex and non-linear optimization theory, and we follow the magnetic domain configuration evolution through part of its magnetization hysteresis loop by applying an external magnetic field. Unlike holographic methods, it does not require a reference wave or precision optics, and so is a far simpler experiment. In addition, it enables the imaging of samples with arbitrarily large spatial dimensions, at a spatial resolution limited solely by the coherent x-ray flux and wavelength. It can readily be extended to other non-magnetic systems that exhibit circular or linear dichroism. This approach is scalable to imaging with diffraction-limited resolution, a prospect rapidly becoming a reality in view of the new generation of phenomenally brilliant x-ray sources.

  5. Vented transmission

    SciTech Connect

    Nguyen, T.H.

    1990-01-29

    This patent describes a vented transmission. It comprises: a housing; a rotary input to the housing; a rotary output from the housing; transmission means within the housing interconnecting the input and the output and including a hollow, rotary shaft journaled within the housing; a vent tube having a first end extending into one end of the hollow shaft and a second end in fluid communication with the exterior of the housing; a shoulder within the hollow shaft and intermediate the ends of the vent tube and defining of relatively smaller diameter section near the first end of the vent tube that is within the hollow shaft and a relatively large diameter section nearer the second end of the vent tube; at least one aperture extending through the hollow shaft from the large diameter section immediately adjacent the shoulder; and a labyrinth seal at the interface of the vent tube and the large diameter section at a location between the aperture (s) and the second end of the vent tube.

  6. Characterization and identification of microorganisms by FT-IR microspectrometry

    NASA Astrophysics Data System (ADS)

    Ngo-Thi, N. A.; Kirschner, C.; Naumann, D.

    2003-12-01

    We report on a novel FT-IR approach for microbial characterization/identification based on a light microscope coupled to an infrared spectrometer which offers the possibility to acquire IR-spectra of microcolonies containing only few hundred cells. Microcolony samples suitable for FT-IR microspectroscopic measurements were obtained by a replica technique with a stamping device that transfers spatially accurate cells of microcolonies growing on solid culture plates to a special, IR-transparent or reflecting stamping plate. High quality spectra could be recorded either by applying the transmission/absorbance or the reflectance/absorbance mode of the infrared microscope. Signal to noise ratios higher than 1000 were obtained for microcolonies as small as 40 μm in diameter. Reproducibility levels were established that allowed species and strain identification. The differentiation and classification capacity of the FT-IR microscopic technique was tested for different selected microorganisms. Cluster and factor analysis methods were used to evaluate the complex spectral data. Excellent discrimination between bacteria and yeasts, and at the same time Gram-negative and Gram-positive bacterial strains was obtained. Twenty-two selected strains of different species within the genus Staphylococcus were repetitively measured and could be grouped into correct species cluster. Moreover, the results indicated that the method allows also identifications at the subspecies level. Additionally, the new approach allowed spectral mapping analysis of single colonies which provided spatially resolved characterization of growth heterogeneity within complex microbial populations such as colonies.

  7. Epitaxial growth and electrochemical transfer of graphene on Ir(111)/α-Al2O3(0001) substrates

    NASA Astrophysics Data System (ADS)

    Koh, Shinji; Saito, Yuta; Kodama, Hideyuki; Sawabe, Atsuhito

    2016-07-01

    Low-pressure chemical vapor deposition growth of graphene on Iridium (Ir) layers epitaxially deposited on α-Al2O3 (0001) substrates was investigated. The X-ray diffraction, Raman and reflection high energy electron diffraction characterizations revealed that graphene films were epitaxially grown on Ir(111) layers, and the in-plane epitaxial relationship between graphene, Ir(111), and α-Al2O3(0001) was graphene ⟨ 1 1 ¯ 00 ⟩//Ir⟨ 11 2 ¯ ⟩//α-Al2O3⟨ 11 2 ¯ 0 ⟩. The graphene on Ir(111) was electrochemically transferred onto SiO2/Si substrates. We also demonstrated the reuse of the Ir(111)/α-Al2O3(0001) substrates in multiple growth and transfer cycles.

  8. Magnetic properties of RE5Ir2X (RE = Y, Gd-Ho, X = Sn, Sb, Pb, Bi) and magnetocaloric characterization of Gd5Ir2X

    NASA Astrophysics Data System (ADS)

    Schäfer, Konrad; Schwickert, Christian; Niehaus, Oliver; Winter, Florian; Pöttgen, Rainer

    2014-09-01

    Systematic phase analytical studies of the systems RE-Ir-X (X = Sn, Pb, Sb, Bi) led to 15 new stannides, plumbides, antimonides and bismuthides with the composition RE5Ir2X. The compounds have been synthesized and characterized by X-ray powder diffraction. The structures of Gd5Ir2Sb and Dy5Ir2Bi have been refined from single crystal X-ray diffractometer data: Mo5SiB2 type, I4/mcm, a = 775.2(2), c = 1361.3(5) pm, wR2 = 0.0933, 404 F2 values, 16 variables for Gd5Ir2Sb and a = 767.5(1), c = 1368.9(3) pm, wR2 = 0.0694, 571 F2 values, 16 variables for Dy5Ir2Bi. Magnetic measurements of Gd5Ir2X (X = Sn, Pb, Sb, Bi), Tb5Ir2X (X = Sn, Pb, Sb, Bi), Dy5Ir2Pb, Dy5Ir2Bi and Ho5Ir2Pb indicate ferromagnetic transitions at TC = 154.3, 159.3, 124.4, 119.3, 99.2, 98.2, 65.5, 68.6, 45.1, 35.6 and 23.5 K, respectively. Gd5Ir2Bi and Gd5Ir2Sb show an additional antiferromagnetic transition at TN = 118.5 and 91.0 K. The magnetocaloric effect of Gd5Ir2X (X = Sn, Pb, Sb, Bi) in terms of the isothermal entropy change ΔSm is -7.3(3), -6.5(3), -8.7(3) and -9.0(3) J kg-1 K-1 at temperatures of 153, 157, 120 and 126 K for a 5 T field change. 119Sn Mössbauer spectra of Gd5Ir2Sn at 78 K show a huge transferred hyperfine field of 21.9(1) T and an isomer shift of 1.94(1) mm s-1, typical for stannides. 121Sb Mössbauer spectra of Gd5Ir2Sb at 78 K show a transferred hyperfine field of 14.2(3) T and an isomer shift of -7.45(8) mm s-1 reflecting the antimonide character.

  9. IR super-resolution microspectroscopy and its application to single cells.

    PubMed

    Sakai, Makoto; Inoue, Keiichi; Fujii, Masaaki

    2013-01-01

    For many years, spatial resolution is the most critical problem in IR microspectroscopy. This is because the spatial resolution of a conventional infrared microscope is restricted by the diffraction limit, which is almost the same as the wavelength of IR light, ranging from 2.5 to 25 μm. In the recent years, we have developed two novel types of far-field IR super-resolution microscopes using 2-color laser spectroscopies, those are transient fluorescence detected IR (TFD-IR) spectroscopy and vibrational sum-frequency generation (VSFG) spectroscopy. In these ways, because both transient fluorescence and VSFG signal have a wavelength in the visible region, the image is observed at the resolution of visible light, which is about 10 times smaller than that of IR light (that is, IR super-resolution). By using these techniques, we can map the specific IR absorption band with sub-micrometer spatial resolution, visualization of the molecular structure and reaction dynamics in a non-uniform environment such as a cell becomes a possibility. In the present reviews, we introduce our novel IR super-resolution microspectroscopy and its application to single cells in detail. PMID:22356113

  10. Diffraction-based optical correlator

    NASA Technical Reports Server (NTRS)

    Spremo, Stevan M. (Inventor); Fuhr, Peter L. (Inventor); Schipper, John F. (Inventor)

    2005-01-01

    Method and system for wavelength-based processing of a light beam. A light beam, produced at a chemical or physical reaction site and having at least first and second wavelengths, ?1 and ?2, is received and diffracted at a first diffraction grating to provide first and second diffracted beams, which are received and analyzed in terms of wavelength and/or time at two spaced apart light detectors. In a second embodiment, light from first and second sources is diffracted and compared in terms of wavelength and/or time to determine if the two beams arise from the same source. In a third embodiment, a light beam is split and diffracted and passed through first and second environments to study differential effects. In a fourth embodiment, diffracted light beam components, having first and second wavelengths, are received sequentially at a reaction site to determine whether a specified reaction is promoted, based on order of receipt of the beams. In a fifth embodiment, a cylindrically shaped diffraction grating (uniform or chirped) is rotated and translated to provide a sequence of diffracted beams with different wavelengths. In a sixth embodiment, incident light, representing one or more symbols, is successively diffracted from first and second diffraction gratings and is received at different light detectors, depending upon the wavelengths present in the incident light.