WorldWideScience

Sample records for time-resolved circularly polarized

  1. Circularly polarized light interaction in topological insulators investigated by time-resolved ARPES

    Science.gov (United States)

    Bugini, D.; Hedayat, H.; Boschini, F.; Yi, H.; Chen, C.; Zhou, X.; Manzoni, C.; Dallera, C.; Cerullo, G.; Carpene, E.

    2017-10-01

    Topological Insulators (TI) represent a hot-topic for both basic physics and promising applications because of the in-plane spin-polarized surface states (TSS) arising within the bulk insulating energy gap. The backscattering protection and the control of the spin polarization using ultrashort light pulses open new scenarios in the use of this class of materials for future opto-spintronic devices. Using time- and angle-resolved photoemission spectroscopy on Sb x Bi(2‑x )Se y Te(3‑y ) class we studied the response of spin-polarized electrons to ultrashort circularly-polarized pulses. Here, we report for the first time the experimental evidence of a direct coupling between light and empty topological surface states (ESS) and the establishment of a flow of spin-polarized electrons in k-space i.e. a photon-induced spin-current.

  2. Near shot-noise limited time-resolved circular dichroism pump-probe spectrometer

    Science.gov (United States)

    Stadnytskyi, Valentyn; Orf, Gregory S.; Blankenship, Robert E.; Savikhin, Sergei

    2018-03-01

    We describe an optical near shot-noise limited time-resolved circular dichroism (TRCD) pump-probe spectrometer capable of reliably measuring circular dichroism signals in the order of μdeg with nanosecond time resolution. Such sensitivity is achieved through a modification of existing TRCD designs and introduction of a new data processing protocol that eliminates approximations that have caused substantial nonlinearities in past measurements and allows the measurement of absorption and circular dichroism transients simultaneously with a single pump pulse. The exceptional signal-to-noise ratio of the described setup makes the TRCD technique applicable to a large range of non-biological and biological systems. The spectrometer was used to record, for the first time, weak TRCD kinetics associated with the triplet state energy transfer in the photosynthetic Fenna-Matthews-Olson antenna pigment-protein complex.

  3. Circularly polarized antennas

    CERN Document Server

    Gao, Steven; Zhu, Fuguo

    2013-01-01

    This book presents a comprehensive insight into the design techniques for different types of CP antenna elements and arrays In this book, the authors address a broad range of topics on circularly polarized (CP) antennas. Firstly, it introduces to the reader basic principles, design techniques and characteristics of various types of CP antennas, such as CP patch antennas, CP helix antennas, quadrifilar helix antennas (QHA), printed quadrifilar helix antennas (PQHA), spiral antenna, CP slot antennas, CP dielectric resonator antennas, loop antennas, crossed dipoles, monopoles and CP horns. Adva

  4. Negative circular polarization as a universal property of quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Taylor, Matthew W.; Spencer, Peter; Murray, Ray [The Blackett Laboratory, Department of Physics, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2015-03-23

    This paper shows that negative circular polarization, a spin flip of polarized carriers resulting in emission of opposite helicity, can be observed in undoped, n-doped, and p-doped InAs/GaAs quantum dots. These results contradict the usual interpretation of the effect. We show using power dependent and time resolved spectroscopy that the generation of negative circular polarization correlates with excited state emission. Furthermore, a longer spin lifetime of negatively polarized excitons is observed where emission is largely ground state in character.

  5. Circular polarization observed in bioluminescence

    NARCIS (Netherlands)

    Wijnberg, Hans; Meijer, E.W.; Hummelen, J.C.; Dekkers, H.P.J.M.; Schippers, P.H.; Carlson, A.D.

    1980-01-01

    While investigating circular polarization in luminescence, and having found it in chemiluminescence, we have studied bioluminescence because it is such a widespread and dramatic natural phenomenon. We report here that left and right lanterns of live larvae of the fireflies, Photuris lucicrescens and

  6. Deflection gating for time-resolved x-ray magnetic circular dichroism-photoemission electron microscopy using synchrotron radiation

    Science.gov (United States)

    Wiemann, C.; Kaiser, A. M.; Cramm, S.; Schneider, C. M.

    2012-06-01

    In this paper, we present a newly developed gating technique for a time-resolving photoemission microscope. The technique makes use of an electrostatic deflector within the microscope's electron optical system for fast switching between two electron-optical paths, one of which is used for imaging, while the other is blocked by an aperture stop. The system can be operated with a switching time of 20 ns and shows superior dark current rejection. We report on the application of this new gating technique to exploit the time structure in the injection bunch pattern of the synchrotron radiation source BESSY II at Helmholtz-Zentrum Berlin for time-resolved measurements in the picosecond regime.

  7. Cygnus X-1: Discovery of variable circular polarization

    International Nuclear Information System (INIS)

    Michalsky, J.J.; Swedlund, J.B.; Stokes, R.A.

    1975-01-01

    HDE 226868, the optical counterpart of Cyg X-1, has been observed for circular polarization during 1974. Observations in five colors suggest that circular polarization results from an interstellar effect. Measurements of the blue polarization reveal circular polarization variations synchronous with the 5)./sub /6 orbital period. The circular polarization variation appears to be similar to the blue intensity variation

  8. Circular Polarization in Turbulent Blazar Jets

    Directory of Open Access Journals (Sweden)

    Nicholas Roy MacDonald

    2017-11-01

    Full Text Available Circular polarization (CP provides an invaluable probe into the underlying plasma content of relativistic jets. CP can be generated within the jet through a physical process known as linear birefringence. This is a physical mechanism through which initially linearly polarized emission produced in one region of the jet is attenuated by Faraday rotation as it passes through other regions of the jet with distinct magnetic field orientations. Marscher developed the turbulent extreme multi-zone (TEMZ model of blazar emission which mimics these types of magnetic geometries with collections of thousands of plasma cells passing through a standing conical shock. I have recently developed a radiative transfer algorithm to generate synthetic images of the time-dependent circularly polarized intensity emanating from the TEMZ model at different radio frequencies. In this study, we produce synthetic multi-epoch observations that highlight the temporal variability in the circular polarization produced by the TEMZ model. We also explore the effect that different plasma compositions within the jet have on the resultant levels of CP.

  9. Study on the interaction of phthalate esters to human serum albumin by steady-state and time-resolved fluorescence and circular dichroism spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xiaoyun [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Wang, Zhaowei [College of Earth and Environmental Sciences, Lanzhou University, Lanzhou 730000 (China); Zhou, Ximin; Wang, Xiaoru [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Chen, Xingguo, E-mail: chenxg@lzu.edu.cn [National Key Laboratory of Organic Chemistry, Lanzhou University, Lanzhou 730000 (China); Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-09-15

    Highlights: {center_dot} Molecular docking revealed PAEs to be located in the hydrophobic pocket of HSA. {center_dot} HSA-DMP had one class of binding sites while HSA-BBP and HSA-DEHP had two types. {center_dot} Hydrophobic and hydrogen interactions dominated in the association of HSA-PAEs. {center_dot} The lifetime of Trp residue of HSA decreased after the addition of PAEs. {center_dot} The presences of PAEs could alter the second structure of HSA. - Abstract: Phthalate esters (PAEs) are globally pervasive contaminants that are considered to be endocrine disruptor chemicals and toxic environmental priority pollutants. In this paper, the interactions between PAEs and human serum albumin (HSA) were examined by molecular modelling, steady state and time-resolved fluorescence, ultraviolet-visible spectroscopy (UV-vis) and circular dichroism spectroscopy (CD). The association constants between PAEs and HSA were determined using the Stern-Volmer and Scatchard equations. The binding of dimethyl phthalate (DMP) to HSA has a single class of binding site and its binding constants (K) are 4.08 x 10{sup 3}, 3.97 x 10{sup 3}, 3.45 x 10{sup 3}, and 3.20 x 10{sup 3} L mol{sup -1} at 289, 296, 303, and 310 K, respectively. The Stern-Volmer and Scatchard plots both had two regression curves for HSA-butylbenzyl phthalate (BBP) and HSA-di-2-ethylhexyl phthalate (DEHP), which indicated that these bindings were via two types of binding sites: the numbers of binding site for the first type were lower than for the second type. The binding constants of the first type binding site were higher than those of the second type binding site at corresponding temperatures, the results suggesting that the first type of binding site had high affinity and the second binding site involved other sites with lower binding affinity and selectivity. The thermodynamic parameters of the binding reactions ({Delta}G{sup o}, {Delta}H{sup o} and {Delta}S{sup o}) were measured, and they indicated the presences

  10. Time-resolved photoluminescence investigation of (Mg, Zn) O alloy growth on a non-polar plane

    Science.gov (United States)

    Mohammed Ali, Mohammed Jassim; Chauveau, J. M.; Bretagnon, T.

    2018-04-01

    Excitons recombination dynamics in ZnMgO alloy have been studied by time-resolved photoluminescence according to temperature. At low temperature, localisation effects of the exciton are found to play a significant role. The photoluminescence (PL) decays are bi-exponential. The short lifetime has a constant value, whereas the long lifetime shows a dependency with temperature. For temperature higher than 100 K the declines show a mono-exponential decay. The PL declines are dominated by non-radiative process at temperatures above 150 K. The PL lifetime dependancy with temperature is analysed using a model including localisation effects and non-radiative recombinations.

  11. High Performance Circularly Polarized Microstrip Antenna

    Science.gov (United States)

    Bondyopadhyay, Probir K. (Inventor)

    1997-01-01

    A microstrip antenna for radiating circularly polarized electromagnetic waves comprising a cluster array of at least four microstrip radiator elements, each of which is provided with dual orthogonal coplanar feeds in phase quadrature relation achieved by connection to an asymmetric T-junction power divider impedance notched at resonance. The dual fed circularly polarized reference element is positioned with its axis at a 45 deg angle with respect to the unit cell axis. The other three dual fed elements in the unit cell are positioned and fed with a coplanar feed structure with sequential rotation and phasing to enhance the axial ratio and impedance matching performance over a wide bandwidth. The centers of the radiator elements are disposed at the corners of a square with each side of a length d in the range of 0.7 to 0.9 times the free space wavelength of the antenna radiation and the radiator elements reside in a square unit cell area of sides equal to 2d and thereby permit the array to be used as a phased array antenna for electronic scanning and is realizable in a high temperature superconducting thin film material for high efficiency.

  12. Bright circularly polarized soft X-ray high harmonics for X-ray magnetic circular dichroism.

    Science.gov (United States)

    Fan, Tingting; Grychtol, Patrik; Knut, Ronny; Hernández-García, Carlos; Hickstein, Daniel D; Zusin, Dmitriy; Gentry, Christian; Dollar, Franklin J; Mancuso, Christopher A; Hogle, Craig W; Kfir, Ofer; Legut, Dominik; Carva, Karel; Ellis, Jennifer L; Dorney, Kevin M; Chen, Cong; Shpyrko, Oleg G; Fullerton, Eric E; Cohen, Oren; Oppeneer, Peter M; Milošević, Dejan B; Becker, Andreas; Jaroń-Becker, Agnieszka A; Popmintchev, Tenio; Murnane, Margaret M; Kapteyn, Henry C

    2015-11-17

    We demonstrate, to our knowledge, the first bright circularly polarized high-harmonic beams in the soft X-ray region of the electromagnetic spectrum, and use them to implement X-ray magnetic circular dichroism measurements in a tabletop-scale setup. Using counterrotating circularly polarized laser fields at 1.3 and 0.79 µm, we generate circularly polarized harmonics with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right circularly polarized peaks, with energies determined by conservation of energy and spin angular momentum. We explain the single-atom and macroscopic physics by identifying the dominant electron quantum trajectories and optimal phase-matching conditions. The first advanced phase-matched propagation simulations for circularly polarized harmonics reveal the influence of the finite phase-matching temporal window on the spectrum, as well as the unique polarization-shaped attosecond pulse train. Finally, we use, to our knowledge, the first tabletop X-ray magnetic circular dichroism measurements at the N4,5 absorption edges of Gd to validate the high degree of circularity, brightness, and stability of this light source. These results demonstrate the feasibility of manipulating the polarization, spectrum, and temporal shape of high harmonics in the soft X-ray region by manipulating the driving laser waveform.

  13. Molecular electron recollision dynamics in intense circularly polarized laser pulses

    Science.gov (United States)

    Bandrauk, André D.; Yuan, Kai-Jun

    2018-04-01

    Extreme UV and x-ray table top light sources based on high-order harmonic generation (HHG) are focused now on circular polarization for the generation of circularly polarized attosecond pulses as new tools for controlling electron dynamics, such as charge transfer and migration and the generation of attosecond quantum electron currents for ultrafast magneto-optics. A fundamental electron dynamical process in HHG is laser induced electron recollision with the parent ion, well established theoretically and experimentally for linear polarization. We discuss molecular electron recollision dynamics in circular polarization by theoretical analysis and numerical simulation. The control of the polarization of HHG with circularly polarized ionizing pulses is examined and it is shown that bichromatic circularly polarized pulses enhance recollision dynamics, rendering HHG more efficient, especially in molecules because of their nonspherical symmetry. The polarization of the harmonics is found to be dependent on the compatibility of the rotational symmetry of the net electric field created by combinations of bichromatic circularly polarized pulses with the dynamical symmetry of molecules. We show how the field and molecule symmetry influences the electron recollision trajectories by a time-frequency analysis of harmonics. The results, in principle, offer new unique controllable tools in the study of attosecond molecular electron dynamics.

  14. Molecular photoelectron holography with circularly polarized laser pulses.

    Science.gov (United States)

    Yang, Weifeng; Sheng, Zhihao; Feng, Xingpan; Wu, Miaoli; Chen, Zhangjin; Song, Xiaohong

    2014-02-10

    We investigate the photoelectron momentum distribution of molecular-ion H2+driven by ultrashort intense circularly polarized laser pulses. Both numerical solutions of the time-dependent Schrödinger equation (TDSE) and a quasiclassical model indicate that the photoelectron holography (PH) with circularly polarized pulses can occur in molecule. It is demonstrated that the interference between the direct electron wave and rescattered electron wave from one core to its neighboring core induces the PH. Moreover, the results of the TDSE predict that there is a tilt angle between the interference pattern of the PH and the direction perpendicular to the molecular axis. Furthermore, the tilt angle is sensitively dependent on the wavelength of the driven circularly polarized pulse, which is confirmed by the quasiclassical calculations. The PH induced by circularly polarized laser pulses provides a tool to resolve the electron dynamics and explore the spatial information of molecular structures.

  15. Spin polarization in quantum dots by radiation field with circular polarization

    CERN Document Server

    Bulgakov, E N

    2001-01-01

    For circular quantum dot (QD) with account of the Razhba spin-orbit interaction (SOI) an exact energy spectrum is obtained. For the small SOI constant the Eigen functions of the QD are found. It is shown that application of radiation field with circular polarization lifts the Kramers degeneracy of the Eigen states of the QD. Effective spin polarization of transmitted electrons through the QD by radiation field with circular polarization is demonstrated

  16. Circular polarization measurements with a Ge(Li) detector

    DEFF Research Database (Denmark)

    Kopecký, J.; Warming, Inge Elisabeth

    1969-01-01

    This paper presents the results obtained in measurements of the degree of circular polarization of gamma transitions to bound states of 33S, 36Cl, 49Ti, 56Mn, 57Fe, 60Co and 64Cu following the capture of polarized thermal neutrons. Spin values have been determined on the basis of these results....

  17. Polymer photovoltaic cells sensitive to the circular polarization of light

    Energy Technology Data Exchange (ETDEWEB)

    Gilot, Jan; Abbel, Robert; Lakhwani, Girish; Meijer, E.W.; Schenning, Albertus P.H.J.; Meskers, Stefan C.J. [Laboratory of Macromolecular and Organic Chemistry, Eindhoven University of Technology (Netherlands)

    2010-05-25

    Chiral conjugated polymer is used to construct a photovoltaic cell whose response depends on the circular polarization of the incoming light. The selectivity for left and right polarized light as a function of the thickness of the polymer layer is accounted for by modeling of the optical properties of all layers inside the device. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  18. Simulation of erasure of photoinduced anisotropy by circularly polarized light

    DEFF Research Database (Denmark)

    Sajti, Sz.; Kerekes, Á.; Barabás, M.

    2001-01-01

    The temporal evolution of photoinduced birefringence is investigated on the basis of a model proposed by Pedersen and co-workers, This model is extended for the case of elliptically polarized light, and used to describe the erasure of photoinduced birefringence by circularly polarized light...

  19. A New Limit on CMB Circular Polarization from SPIDER

    Energy Technology Data Exchange (ETDEWEB)

    Nagy, J. M.; Ade, P. A. R.; Amiri, M.; Benton, S. J.; Bergman, A. S.; Bihary, R.; Bock, J. J.; Bond, J. R.; Bryan, S. A.; Chiang, H. C.; Contaldi, C. R.; Doré, O.; Duivenvoorden, A. J.; Eriksen, H. K.; Farhang, M.; Filippini, J. P.; Fissel, L. M.; Fraisse, A. A.; Freese, K.; Galloway, M.; Gambrel, A. E.; Gandilo, N. N.; Ganga, K.; Gudmundsson, J. E.; Halpern, M.; Hartley, J.; Hasselfield, M.; Hilton, G.; Holmes, W.; Hristov, V. V.; Huang, Z.; Irwin, K. D.; Jones, W. C.; Kuo, C. L.; Kermish, Z. D.; Li, S.; Mason, P. V.; Megerian, K.; Moncelsi, L.; Morford, T. A.; Netterfield, C. B.; Nolta, M.; Padilla, I. L.; Racine, B.; Rahlin, A. S.; Reintsema, C.; Ruhl, J. E.; Runyan, M. C.; Ruud, T. M.; Shariff, J. A.; Soler, J. D.; Song, X.; Trangsrud, A.; Tucker, C.; Tucker, R. S.; Turner, A. D.; List, J. F. Van Der; Weber, A. C.; Wehus, I. K.; Wiebe, D. V.; Young, E. Y.

    2017-08-01

    We present a new upper limit on CMB circular polarization from the 2015 flight of SPIDER, a balloon-borne telescope designed to search for $B$-mode linear polarization from cosmic inflation. Although the level of circular polarization in the CMB is predicted to be very small, experimental limits provide a valuable test of the underlying models. By exploiting the non-zero circular-to-linear polarization coupling of the HWP polarization modulators, data from SPIDER's 2015 Antarctic flight provides a constraint on Stokes $V$ at 95 and 150 GHz from $33<\\ell<307$. No other limits exist over this full range of angular scales, and SPIDER improves upon the previous limit by several orders of magnitude, providing 95% C.L. constraints on $\\ell (\\ell+1)C_{\\ell}^{VV}/(2\\pi)$ ranging from 141 $\\mu K ^2$ to 203 $\\mu K ^2$ at 150 GHz for a thermal CMB spectrum. As linear CMB polarization experiments become increasingly sensitive, the techniques described in this paper can be applied to obtain stronger constraints on circular polarization.

  20. Circular polarization in a non-magnetic resonant tunneling device

    Directory of Open Access Journals (Sweden)

    Airey Robert

    2011-01-01

    Full Text Available Abstract We have investigated the polarization-resolved photoluminescence (PL in an asymmetric n-type GaAs/AlAs/GaAlAs resonant tunneling diode under magnetic field parallel to the tunnel current. The quantum well (QW PL presents strong circular polarization (values up to -70% at 19 T. The optical emission from GaAs contact layers shows evidence of highly spin-polarized two-dimensional electron and hole gases which affects the spin polarization of carriers in the QW. However, the circular polarization degree in the QW also depends on various other parameters, including the g-factors of the different layers, the density of carriers along the structure, and the Zeeman and Rashba effects.

  1. Slotted Circularly Polarized Microstrip Antenna for RFID Application

    Directory of Open Access Journals (Sweden)

    S. Kumar

    2017-12-01

    Full Text Available A single layer coaxial fed rectangular microstrip slotted antenna for circular polarization (CP is proposed for radio frequency identification (RFID application. Two triangular shaped slots and one rectangular slot along the diagonal axis of a square patch have been embedded. Due to slotted structure along the diagonal axis and less surface area, good quality of circular polarization has been obtained with the reduction in the size of microstrip antenna by 4.04 %. Circular polarization radiation performance has been studied by size and angle variation of diagonally slotted structures. The experimental result found for 10-dB return loss is 44 MHz with 10MHz of 3dB Axial Ratio (AR bandwidth respectively at the resonant frequency 910 MHz. The overall proposed antenna size including the ground plane is 80 mm x 80 mm x 4.572 mm.

  2. Inkjet printed circularly polarized antennas for GPS applications

    KAUST Repository

    Farooqui, Muhammad Fahad

    2014-07-01

    Two novel, inkjet printed circularly polarized antenna designs are presented for GPS applications. First antenna design comprises a planar monopole which has been made circularly polarized by the introduction of an L-shaped slit. The antenna shows a gain of 0.2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 3.8%. The second antenna design comprises a modified monopole in the form of an inverted L and has been termed as circularly polarized inverted L antenna (CILA). The antenna shows a gain of -2 dBi at 1.575 GHz with 3-dB axial ratio bandwidth of 4.1%. Both the antenna designs are attractive for mobile applications.

  3. A simple circular-polarized antenna: Circular waveguide horn coated with lossy magnetic material

    Science.gov (United States)

    Lee, Choon S.; Justice, D. W.; Lee, Shung-Wu

    1988-01-01

    It is shown that a circular waveguide horn coated with a lossy material in its interior wall can be used as an alternative to a corrugated waveguide for radiating a circularly polarized (CP) field. To achieve good CP radiation, the diameter of the structure must be larger than the free-space wavelength, and the coating material must be sufficiently lossy and magnetic. The device is cheaper and lighter in weight than the corrugated one.

  4. Acceleration of polarized protons in circular accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Courant, E.D.; Ruth, R.D.

    1980-09-12

    The theory of depolarization in circular accelerators is presented. The spin equation is first expressed in terms of the particle orbit and then converted to the equivalent spinor equation. The spinor equation is then solved for three different situations: (1) a beam on a flat top near a resonance, (2) uniform acceleration through an isolated resonance, and (3) a model of a fast resonance jump. Finally, the depolarization coefficient, epsilon, is calculated in terms of properties of the particle orbit and the results are applied to a calculation of depolarization in the AGS.

  5. Gold helix photonic metamaterial as broadband circular polarizer.

    Science.gov (United States)

    Gansel, Justyna K; Thiel, Michael; Rill, Michael S; Decker, Manuel; Bade, Klaus; Saile, Volker; von Freymann, Georg; Linden, Stefan; Wegener, Martin

    2009-09-18

    We investigated propagation of light through a uniaxial photonic metamaterial composed of three-dimensional gold helices arranged on a two-dimensional square lattice. These nanostructures are fabricated via an approach based on direct laser writing into a positive-tone photoresist followed by electrochemical deposition of gold. For propagation of light along the helix axis, the structure blocks the circular polarization with the same handedness as the helices, whereas it transmits the other, for a frequency range exceeding one octave. The structure is scalable to other frequency ranges and can be used as a compact broadband circular polarizer.

  6. Monolithic Superconducting Emitter of Tunable Circularly Polarized Terahertz Radiation

    Science.gov (United States)

    Elarabi, A.; Yoshioka, Y.; Tsujimoto, M.; Kakeya, I.

    2017-12-01

    We propose an approach to controlling the polarization of terahertz (THz) radiation from intrinsic Josephson-junction stacks in a single crystalline high-temperature superconductor Bi2Sr2CaCu2O8 . Monolithic control of the surface high-frequency current distributions in the truncated square mesa structure allows us to modulate the polarization of the emitted terahertz wave as a result of two orthogonal fundamental modes excited inside the mesa. Highly polarized circular terahertz waves with a degree of circular polarization of more than 99% can be generated using an electrically controlled method. The intuitive results obtained from the numerical simulation based on the conventional antenna theory are consistent with the observed emission characteristics.

  7. Circular polarization in the optical afterglow of GRB 121024A.

    Science.gov (United States)

    Wiersema, K; Covino, S; Toma, K; van der Horst, A J; Varela, K; Min, M; Greiner, J; Starling, R L C; Tanvir, N R; Wijers, R A M J; Campana, S; Curran, P A; Fan, Y; Fynbo, J P U; Gorosabel, J; Gomboc, A; Götz, D; Hjorth, J; Jin, Z P; Kobayashi, S; Kouveliotou, C; Mundell, C; O'Brien, P T; Pian, E; Rowlinson, A; Russell, D M; Salvaterra, R; di Serego Alighieri, S; Tagliaferri, G; Vergani, S D; Elliott, J; Fariña, C; Hartoog, O E; Karjalainen, R; Klose, S; Knust, F; Levan, A J; Schady, P; Sudilovsky, V; Willingale, R

    2014-05-08

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of the jet when measured minutes after the burst, and it probes the geometric properties of the jet and the ambient medium when measured hours to days after the burst. High values of optical polarization detected minutes after the burst of GRB 120308A indicate the presence of large-scale ordered magnetic fields originating from the central engine (the power source of the GRB). Theoretical models predict low degrees of linear polarization and no circular polarization at late times, when the energy in the original ejecta is quickly transferred to the ambient medium and propagates farther into the medium as a blast wave. Here we report the detection of circularly polarized light in the afterglow of GRB 121024A, measured 0.15 days after the burst. We show that the circular polarization is intrinsic to the afterglow and unlikely to be produced by dust scattering or plasma propagation effects. A possible explanation is to invoke anisotropic (rather than the commonly assumed isotropic) electron pitch-angle distributions, and we suggest that new models are required to produce the complex microphysics of realistic shocks in relativistic jets.

  8. Circularly polarized millimeter-wave imaging for personnel screening

    Science.gov (United States)

    Sheen, David M.; McMakin, Douglas L.; Lechelt, Wayne M.; Griffin, Jeffrey W.

    2005-05-01

    A novel polarimetric millimeter-wave imaging technique has been developed at the Pacific Northwest National Laboratory (PNNL) for concealed weapon detection applications. Wideband millimeter-wave imaging systems developed at PNNL utilize low-power, coherent, millimeter-wave illumination in the 10-100 GHz range to form high-resolution images of personnel. Electromagnetic waves in these frequency ranges easily penetrate most clothing materials and are reflected from the body and any concealed items. Three-dimensional images are formed using computer image reconstruction algorithms developed to mathematically focus the received wavefronts scattered from the target. Circular polarimetric imaging can be employed to obtain additional information from the target. Circularly polarized waves incident on relatively smooth reflecting targets are typically reversed in their rotational handedness, e.g. left-hand circular polarization (LHCP) is reflected to become right-hand circular polarization (RHCP). An incident wave that is reflected twice (or any even number) of times prior to returning to the transceiver, has its handedness preserved. Sharp features such as wires and edges tend to return linear polarization, which can be considered to be a sum of both LHCP and RHCP. These characteristics can be exploited for personnel screening by allowing differentiation of smooth features, such as the body, and sharper features present in many concealed items. Additionally, imaging artifacts due to multipath can be identified and eliminated. Laboratory imaging results have been obtained in the 10-20 GHz frequency range and are presented in this paper.

  9. Multiband Circular Polarizer Based on Fission Transmission of Linearly Polarized Wave for X-Band Applications

    Directory of Open Access Journals (Sweden)

    Farman Ali Mangi

    2016-01-01

    Full Text Available A multiband circular polarizer based on fission transmission of linearly polarized wave for x-band application is proposed, which is constructed of 2 × 2 metallic strips array. The linear-to-circular polarization conversion is obtained by decomposing the linearly incident x-polarized wave into two orthogonal vector components of equal amplitude and 90° phase difference between them. The innovative approach of “fission transmission of linear-to-circular polarized wave” is firstly introduced to obtain giant circular dichroism based on decomposition of orthogonal vector components through the structure. It means that the incident linearly polarized wave is converted into two orthogonal components through lower printed metallic strips layer and two transmitted waves impinge on the upper printed strips layer to convert into four orthogonal vector components at the end of structure. This projection and transmission sequence of orthogonal components sustain the chain transmission of electromagnetic wave and can achieve giant circular dichroism. Theoretical analysis and microwave experiments are presented to validate the performance of the structure. The measured results are in good agreement with simulation results. In addition, the proposed circular polarizer exhibits the optimal performance with respect to the normal incidence. The right handed circularly polarized wave is emitted ranging from 10.08 GHz to 10.53 GHz and 10.78 GHz to 11.12 GHz, while the left handed circular polarized wave is excited at 10.54 GHz–10.70 GHz and 11.13 GHz–11.14 GHz, respectively.

  10. Analysis of Circular Polarization of Cylindrically Bent Microstrip Antennas

    Directory of Open Access Journals (Sweden)

    Tiiti Kellomäki

    2012-01-01

    Full Text Available When circularly polarized (CP microstrip antennas are bent, the polarization becomes elliptical. We present a simple model that describes the phenomenon. The two linear modes present in a CP patch are modeled separately and added together to produce CP. Bending distorts the almost-spherical equiphase surface of a linearly polarized patch, which leads to phase imbalance in the far-field of a CP patch. The model predicts both the frequency shifting of the axial ratio band as well as the narrowing of the axial ratio beam. Uncontrolled bending is a problem associated especially with flexible textile antennas, and wearable antennas should therefore be designed somewhat conformal.

  11. Polarization dependent switching of asymmetric nanorings with a circular field

    Directory of Open Access Journals (Sweden)

    Nihar R. Pradhan

    2016-01-01

    Full Text Available We experimentally investigated the switching from onion to vortex states in asymmetric cobalt nanorings by an applied circular field. An in-plane field is applied along the symmetric or asymmetric axis of the ring to establish domain walls (DWs with symmetric or asymmetric polarization. A circular field is then applied to switch from the onion state to the vortex state, moving the DWs in the process. The asymmetry of the ring leads to different switching fields depending on the location of the DWs and direction of applied field. For polarization along the asymmetric axis, the field required to move the DWs to the narrow side of the ring is smaller than the field required to move the DWs to the larger side of the ring. For polarization along the symmetric axis, establishing one DW in the narrow side and one on the wide side, the field required to switch to the vortex state is an intermediate value.

  12. Modeling radio circular polarization in the Crab nebula

    Science.gov (United States)

    Bucciantini, N.; Olmi, B.

    2018-03-01

    In this paper, we present, for the first time, simulated maps of the circularly polarized synchrotron emission from the Crab nebula, using multidimensional state of the art models for the magnetic field geometry. Synchrotron emission is the signature of non-thermal emitting particles, typical of many high-energy astrophysical sources, both Galactic and extragalactic ones. Its spectral and polarization properties allow us to infer key information on the particles distribution function and magnetic field geometry. In recent years, our understanding of pulsar wind nebulae has improved substantially thanks to a combination of observations and numerical models. A robust detection or non-detection of circular polarization will enable us to discriminate between an electron-proton plasma and a pair plasma, clarifying once for all the origin of the radio emitting particles, setting strong constraints on the pair production in pulsar magnetosphere, and the role of turbulence in the nebula. Previous attempts at measuring the circular polarization have only provided upper limits, but the lack of accurate estimates, based on reliable models, makes their interpretation ambiguous. We show here that those results are above the expected values, and that current polarimetric techniques are not robust enough for conclusive result, suggesting that improvements in construction and calibration of next generation radio facilities are necessary to achieve the desired sensitivity.

  13. Polarization-Dependent Multi-Functional Metamaterial as Polarization Filter, Transparent Wall and Circular Polarizer using Ring-Cross Resonator

    Directory of Open Access Journals (Sweden)

    Z. Zhang

    2017-09-01

    Full Text Available We propose a polarization-dependent multi-functional metamaterial using ring-cross resonator. Based on the analysis of surface current distributions induced by different polarized incidence, we demonstrate that the proposed metamaterial serves as a polarization filter, a transparent wall and a circular polarizer under different polarization normal incidence. Additionally, parameter analyses on the control of resonance are discussed to complementally explain the physical origin. Simulated results show that the proposed metamaterial functions as a polarization filter eliminating the x-polarization wave at 10.1 GHz and y-polarization wave at 14.3 GHz, a transparent wall transmitting both x-polarized and y-polarized incident waves at 12.6 GHz, and a broadband circular polarizer converting the +45° polarized (-45° polarized incident wave to the left (right handed circularly polarized wave from 10.8 to 12.8 GHz, respectively. Measured results agree well with the simulation and validate the performance of the proposed multifunctional metamaterial.

  14. Polarization measurement and vertical aperture optimization for obtaining circularly polarized bend-magnet radiation

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Rice, M.; Hussain, Z. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Growing interest in utilizing circular polarization prompted the design of bend-magnet beamline 9.3.2 at the Advanced Light Source, covering the 30-1500 eV spectral region, to include vertical aperturing capabilities for optimizing the collection of circular polarization above and below the orbit plane. After commissioning and early use of the beamline, a multilayer polarimeter was used to characterize the polarization state of the beam as a function of vertical aperture position. This report partially summarizes the polarimetry measurements and compares results with theoretical calculations intended to simulate experimental conditions.

  15. A Novel Dual-Band Circularly Polarized Rectangular Slot Antenna

    Directory of Open Access Journals (Sweden)

    Biao Li

    2016-01-01

    Full Text Available A coplanar waveguide fed dual-band circularly polarized rectangular slot antenna is presented. The proposed antenna consists of a rectangular metal frame acting as a ground and an S-shaped monopole as a radiator. The spatial distribution of the surface current density is employed to demonstrate that the circular polarization is generated by the S-shaped monopole which controls the path of the surface currents. An antenna prototype, having overall dimension 37 × 37 × 1 mm3, has been fabricated on FR4 substrate with dielectric constant 4.4. The proposed antenna achieves 10 dB return loss bandwidths and 3 dB axial ratio (AR in the frequency bands 2.39–2.81 GHz and 5.42–5.92 GHz, respectively. Both these characteristics are suitable for WLAN and WiMAX applications.

  16. Full-Stokes polarimetry with circularly polarized feeds. Sources with stable linear and circular polarization in the GHz regime

    Science.gov (United States)

    Myserlis, I.; Angelakis, E.; Kraus, A.; Liontas, C. A.; Marchili, N.; Aller, M. F.; Aller, H. D.; Karamanavis, V.; Fuhrmann, L.; Krichbaum, T. P.; Zensus, J. A.

    2018-01-01

    We present an analysis pipeline that enables the recovery of reliable information for all four Stokes parameters with high accuracy. Its novelty relies on the effective treatment of the instrumental effects even before the computation of the Stokes parameters, contrary to conventionally used methods such as that based on the Müller matrix. For instance, instrumental linear polarization is corrected across the whole telescope beam and significant Stokes Q and U can be recovered even when the recorded signals are severely corrupted by instrumental effects. The accuracy we reach in terms of polarization degree is of the order of 0.1-0.2%. The polarization angles are determined with an accuracy of almost 1°. The presented methodology was applied to recover the linear and circular polarization of around 150 active galactic nuclei, which were monitored between July 2010 and April 2016 with the Effelsberg 100-m telescope at 4.85 GHz and 8.35 GHz with a median cadence of 1.2 months. The polarized emission of the Moon was used to calibrate the polarization angle measurements. Our analysis showed a small system-induced rotation of about 1° at both observing frequencies. Over the examined period, five sources have significant and stable linear polarization; three sources remain constantly linearly unpolarized; and a total of 11 sources have stable circular polarization degree mc, four of them with non-zero mc. We also identify eight sources that maintain a stable polarization angle. All this is provided to the community for future polarization observations reference. We finally show that our analysis method is conceptually different from those traditionally used and performs better than the Müller matrix method. Although it has been developed for a system equipped with circularly polarized feeds, it can easily be generalized to systems with linearly polarized feeds as well. The data used to create Fig. C.1 are only available at the CDS via anonymous ftp to http

  17. Time-resolved studies

    International Nuclear Information System (INIS)

    Mills, D.M.

    1992-01-01

    When new or more powerful probes become available that offer both shorter data-collection times and the opportunity to apply innovative approaches to established techniques, it is natural that investigators consider the feasibility of exploring the kinetics of time-evolving systems. This stimulating area of research not only can lead to insights into the metastable or excited states that a system may populate on its way to a ground state, but can also lead to a better understanding of that final state. Synchrotron radiation, with its unique properties, offers just such a tool to extend X-ray measurements from the static to the time-resolved regime. The most straight-forward application of synchrotron radiation to the study of transient phenomena is directly through the possibility of decreased data-collection times via the enormous increase in flux over that of a laboratory X-ray system. Even further increases in intensity can be obtained through the use of novel X-ray optical devices. Widebandpass monochromators, e.g., that utilize the continuous spectral distribution of synchrotron radiation, can increase flux on the sample several orders of magnitude over conventional X-ray optical systems thereby allowing a further shortening of the data-collection time. Another approach that uses the continuous spectral nature of synchrotron radiation to decrease data-collection times is the open-quote parallel data collectionclose quotes method. Using this technique, intensities as a function of X-ray energy are recorded simultaneously for all energies rather than sequentially recording data at each energy, allowing for a dramatic decrease in the data-collection time

  18. A computational protocol for the study of circularly polarized phosphorescence and circular dichroism in spin-forbidden absorption

    DEFF Research Database (Denmark)

    Kaminski, Maciej; Cukras, Janusz; Pecul, Magdalena

    2015-01-01

    We present a computational methodology to calculate the intensity of circular dichroism (CD) in spinforbidden absorption and of circularly polarized phosphorescence (CPP) signals, a manifestation of the optical activity of the triplet–singlet transitions in chiral compounds. The protocol is based...... on the response function formalism and is implemented at the level of time-dependent density functional theory. It has been employed to calculate the spin-forbidden circular dichroism and circularly polarized phosphorescence signals of valence n - p* and n ’ p* transitions, respectively, in several chiral enones...

  19. Differential response to circularly polarized light by the jewel scarab beetle Chrysina gloriosa.

    Science.gov (United States)

    Brady, Parrish; Cummings, Molly

    2010-05-01

    Circularly polarized light is rare in the terrestrial environment, and cuticular reflections from scarab beetles are one of the few natural sources. Chrysina gloriosa LeConte 1854, a scarab beetle found in montane juniper forests of the extreme southwestern United States and northern Mexico, are camouflaged in juniper foliage; however, when viewed with right circularly polarizing filters, the beetles exhibit a stark black contrast. Given the polarization-specific changes in the appearance of C. gloriosa, we hypothesized that C. gloriosa can detect circularly polarized light. We tested for phototactic response and differential flight orientation of C. gloriosa toward different light stimuli. Chrysina gloriosa exhibited (a) positive phototaxis, (b) differential flight orientation between linear and circularly polarized light stimuli of equal intensities, and (c) discrimination between circularly polarized and unpolarized lights of different intensities consistent with a model of circular polarization sensitivity based on a quarter-wave plate. These results demonstrate that C. gloriosa beetles respond differentially to circularly polarized light. In contrast, Chrysina woodi Horn 1885, a close relative with reduced circularly polarized reflection, exhibited no phototactic discrimination between linear and circularly polarized light. Circularly polarized sensitivity may allow C. gloriosa to perceive and communicate with conspecifics that remain cryptic to predators, reducing indirect costs of communication.

  20. Generation of Gigawatt Circularly Polarized Attosecond-Pulse Pairs

    Science.gov (United States)

    Hu, K.; Wu, H.-C.

    2017-12-01

    A novel scheme for generating a pair of gigawatt attosecond pulses by coherent Thomson scattering from relativistic electron sheets is proposed. With a circularly polarized relativistic laser pulse, the scattered x-ray signal can have a saddlelike temporal profile, where the lower electromagnetic frequencies are found mostly in the center region of this saddlelike profile. By filtering out the latter, we can obtain two few-attosecond pulses separated by a subfemtosecond interval, which is tunable by controlling the energy of the sheet electrons. Such a pulse pair can be useful for an attosecond pump probe at an unprecedented time resolution and for ultrafast chiral studies in molecules and materials.

  1. Electron Interference in Molecular Circular Polarization Attosecond XUV Photoionization

    Directory of Open Access Journals (Sweden)

    Kai-Jun Yuan

    2015-01-01

    Full Text Available Two-center electron interference in molecular attosecond photoionization processes is investigated from numerical solutions of time-dependent Schrödinger equations. Both symmetric H\\(_2^+\\ and nonsymmetric HHe\\(^{2+}\\ one electron diatomic systems are ionized by intense attosecond circularly polarized XUV laser pulses. Photoionization of these molecular ions shows signature of interference with double peaks (minima in molecular attosecond photoelectron energy spectra (MAPES at critical angles \\(\\vartheta_c\\ between the molecular \\(\\textbf{R}\\ axis and the photoelectron momentum \\(\\textbf{p}\\. The interferences are shown to be a function of the symmetry of electronic states and the interference patterns are sensitive to the molecular orientation and pulse polarization. Such sensitivity offers possibility for imaging of molecular structure and orbitals.

  2. A study of relaxation mechanisms in the A{sup 2}{Sigma}{sup +} state of nitric oxide by time resolved double resonant polarization spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stampanoni-Panariello, A.; Bombach, R.; Hemmerling, B.; Hubschmid, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland)

    1997-06-01

    Double resonant polarization labeling spectroscopy is applied to detect nitric oxide in flames and to characterize rotational energy transfer and orientation changing collisions in its first excited electronic state. (author) 4 figs., 3 refs.

  3. Cross-polarization detection enables fast measurement of vibrational circular dichroism

    Czech Academy of Sciences Publication Activity Database

    Bouř, Petr

    2009-01-01

    Roč. 10, č. 12 (2009), s. 1983-1985 ISSN 1439-4235 Institutional research plan: CEZ:AV0Z40550506 Keywords : vibrational circular dichroism * time-resolved experiment Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 3.453, year: 2009

  4. A Minkowski Fractal Circularly Polarized Antenna for RFID Reader

    Directory of Open Access Journals (Sweden)

    Yanzhong Yu

    2014-11-01

    Full Text Available A design of fractal-like antenna with circular polarization for radio frequency identification (RFID reader applications is presented in this article. The modified Minkowski fractal structure is adopted as radiating patch for size reduction and broadband operation. A corner-truncated technology and a slot-opened method are employed to realize circular polarization and improve the gain of the proposed antenna, respectively. The proposed antenna is analyzed and optimized by HFSS. Return loss and maximum gain of the optimized antenna achieve to -22.2 dB and 1.12 dB at 920 MHz, respectively. The optimized design has an axial ratio (AR of 1.2 dB at central frequency of 920 MHz and impedance bandwidth (S11<=-10 dB of 40 MHz (4.3 %. Its input impedance is (57.9-j2.6 W that is close to input impedance of coaxial line (50 W. Numerical results demonstrate that the optimized antenna exhibits acceptable performances and may satisfy requirements of RFID reader applications.

  5. Multi-band circular polarizer based on a twisted triple split-ring resonator

    International Nuclear Information System (INIS)

    Wu Song; Huang Xiao-Jun; Yang He-Lin; Xiao Bo-Xun; Jin Yan

    2014-01-01

    A multi-band circular polarizer using a twisted triple split-ring resonator (TSRR) is presented and studied numerically and experimentally. At four distinct resonant frequencies, the incident linearly polarized wave can be transformed into left/right-handed circularly polarized waves. Numerical simulation results show that a y-polarized wave can be converted into a right-handed circularly polarized wave at 5.738 GHz and 9.218 GHz, while a left-handed circularly polarized wave is produced at 7.292 GHz and 10.118 GHz. The experimental results are in agreement with the numerical results. The surface current distributions are investigated to illustrate the polarization transformation mechanism. Furthermore, the influences of the structure parameters of the circular polarizer on transmission spectra are discussed as well. (condensed matter: electronic structure, electrical, magnetic, and optical properties)

  6. Annular billiard dynamics in a circularly polarized strong laser field

    Science.gov (United States)

    Kamor, A.; Mauger, F.; Chandre, C.; Uzer, T.

    2012-01-01

    We analyze the dynamics of a valence electron of the buckminsterfullerene molecule (C60) subjected to a circularly polarized laser field by modeling it with the motion of a classical particle in an annular billiard. We show that the phase space of the billiard model gives rise to three distinct trajectories: “whispering gallery orbits,” which hit only the outer billiard wall; “daisy orbits,” which hit both billiard walls (while rotating solely clockwise or counterclockwise for all time); and orbits that only visit the downfield part of the billiard, as measured relative to the laser term. These trajectories, in general, maintain their distinct features, even as the intensity is increased from 1010 to 1014Wcm-2. We attribute this robust separation of phase space to the existence of twistless tori.

  7. Komar fluxes of circularly polarized light beams and cylindrical metrics

    Science.gov (United States)

    Lynden-Bell, D.; Bičák, J.

    2017-11-01

    The mass per unit length of a cylindrical system can be found from its external metric as can its angular momentum. Can the fluxes of energy, momentum, and angular momentum along the cylinder also be so found? We derive the metric of a beam of circularly polarized electromagnetic radiation from the Einstein-Maxwell equations. We show how the uniform plane wave solutions miss the angular momentum carried by the wave. We study the energy, momentum, angular momentum, and their fluxes along the cylinder both for this beam and in general. The three Killing vectors of any stationary cylindrical system give three Komar flux vectors which in turn give six conserved fluxes. We elucidate Komar's mysterious factor 2 by evaluating Komar integrals for systems that have no trace to their stress tensors. The Tolman-Komar formula gives twice the energy for such systems which also have twice the gravity. For other cylindrical systems their formula gives correct results.

  8. Vertical-Strip-Fed Broadband Circularly Polarized Dielectric Resonator Antenna.

    Science.gov (United States)

    Altaf, Amir; Jung, Jin-Woo; Yang, Youngoo; Lee, Kang-Yoon; Hwang, Keum Cheol

    2017-08-18

    A vertical-strip-fed dielectric resonator antenna exhibiting broadband circular polarization characteristics is presented. A broad 3 dB axial ratio bandwidth (ARBW) is achieved by combining multiple orthogonal modes due to the use of a special-shaped dielectric resonator. The proposed antenna is fabricated to evaluate its actual performance capabilities. The antenna exhibits a measured 3 dB ARBW of 44.2% (3.35-5.25 GHz), lying within a -10 dB reflection bandwidth of 82.7% (2.44-5.88 GHz). The measured peak gain within 3 dB ARBW is found to be 5.66 dBic at 4.8 GHz. The measured results are in good agreement with the simulated results.

  9. A survey of synchrotron radiation devices producing circular or variable polarization

    International Nuclear Information System (INIS)

    Kim, K.J.

    1990-01-01

    This paper reviews the properties and operating principles of the new types of synchrotron radiation devices that produce circular polarization, or polarization that can be modulated in arbitrary fashion

  10. Circularly polarized near-field optical mapping of spin-resolved quantum Hall chiral edge states.

    Science.gov (United States)

    Mamyouda, Syuhei; Ito, Hironori; Shibata, Yusuke; Kashiwaya, Satoshi; Yamaguchi, Masumi; Akazaki, Tatsushi; Tamura, Hiroyuki; Ootuka, Youiti; Nomura, Shintaro

    2015-04-08

    We have successfully developed a circularly polarized near-field scanning optical microscope (NSOM) that enables us to irradiate circularly polarized light with spatial resolution below the diffraction limit. As a demonstration, we perform real-space mapping of the quantum Hall chiral edge states near the edge of a Hall-bar structure by injecting spin polarized electrons optically at low temperature. The obtained real-space mappings show that spin-polarized electrons are injected optically to the two-dimensional electron layer. Our general method to locally inject spins using a circularly polarized NSOM should be broadly applicable to characterize a variety of nanomaterials and nanostructures.

  11. Ligand Induced Circular Dichroism and Circularly Polarized Luminescence in CdSe Quantum Dots

    Science.gov (United States)

    Tohgha, Urice; Deol, Kirandeep K.; Porter, Ashlin G.; Bartko, Samuel G.; Choi, Jung Kyu; Leonard, Brian M.; Varga, Krisztina; Kubelka, Jan; Muller, Gilles; Balaz, Milan

    2014-01-01

    Chiral thiol capping ligands L- and D-cysteines induced modular chiroptical properties in achiral cadmium selenide quantum dots (CdSe QDs). Cys-CdSe prepared from achiral oleic acid capped CdSe by post-synthetic ligand exchange displayed size-dependent electronic circular dichroism (CD) and circularly polarized luminescence (CPL). Opposite CPL signals were measured for the CdSe QDs capped with D- and L-cysteine. The CD profile and CD anisotropy varied with size of CdSe nanocrystals with largest anisotropy observed for CdSe nanoparticles of 4.4 nm. Magic angle spinning solid state NMR (MAS ssNMR) experiments suggested bidentate interaction between cysteine and the surface of CdSe. Density functional theory (DFT) calculations verified that attachment of L- and D-cysteine to the surface of model (CdSe)13 nanoclusters induces measurable opposite CD signals for the exitonic band of the nanocluster. The chirality was induced by the hybridization of highest occupied CdSe molecular orbitals with those of the chiral ligand. PMID:24200288

  12. Analysis of the multipactor effect in circular waveguides excited by two orthogonal polarization waves

    International Nuclear Information System (INIS)

    Pérez, A. M.; Boria, V. E.; Gimeno, B.; Anza, S.; Vicente, C.; Gil, J.

    2014-01-01

    Circular waveguides, either employed as resonant cavities or as irises connecting adjacent guides, are widely present in many passive components used in different applications (i.e., particle accelerators and satellite subsystems). In this paper, we present the study of the multipactor effect in circular waveguides considering the coexistence of the two polarizations of the fundamental TE 11 circular waveguide mode. For a better understanding of the problem, only low multipactor orders have been explored as a function of the polarization ellipse eccentricity. Special attention has been paid to the linear and circular polarizations, but other more general configurations have also been explored

  13. Analysis of the multipactor effect in circular waveguides excited by two orthogonal polarization waves

    Energy Technology Data Exchange (ETDEWEB)

    Pérez, A. M.; Boria, V. E. [Departamento de Comunicaciones-iTEAM, Universidad Politécnica de Valencia Camino de Vera s/n, 46022 Valencia (Spain); Gimeno, B. [Departamento de Física Aplicada y Electromagnetismo-ICMUV, Universitat de València c/Dr. Moliner, 50, 46100 Valencia (Spain); Anza, S.; Vicente, C.; Gil, J. [Aurora Software and Testing S.L., Edificio de Desarrollo Empresarial 9B, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia (Spain)

    2014-08-15

    Circular waveguides, either employed as resonant cavities or as irises connecting adjacent guides, are widely present in many passive components used in different applications (i.e., particle accelerators and satellite subsystems). In this paper, we present the study of the multipactor effect in circular waveguides considering the coexistence of the two polarizations of the fundamental TE{sub 11} circular waveguide mode. For a better understanding of the problem, only low multipactor orders have been explored as a function of the polarization ellipse eccentricity. Special attention has been paid to the linear and circular polarizations, but other more general configurations have also been explored.

  14. Time resolved techniques: An overview

    International Nuclear Information System (INIS)

    Larson, B.C.; Tischler, J.Z.

    1990-06-01

    Synchrotron sources provide exceptional opportunities for carrying out time-resolved x-ray diffraction investigations. The high intensity, high angular resolution, and continuously tunable energy spectrum of synchrotron x-ray beams lend themselves directly to carrying out sophisticated time-resolved x-ray scattering measurements on a wide range of materials and phenomena. When these attributes are coupled with the pulsed time-structure of synchrotron sources, entirely new time-resolved scattering possibilities are opened. Synchrotron beams typically consist of sub-nanosecond pulses of x-rays separated in time by a few tens of nanoseconds to a few hundred nanoseconds so that these beams appear as continuous x-ray sources for investigations of phenomena on time scales ranging from hours down to microseconds. Studies requiring time-resolution ranging from microseconds to fractions of a nanosecond can be carried out in a triggering mode by stimulating the phenomena under investigation in coincidence with the x-ray pulses. Time resolution on the picosecond scale can, in principle, be achieved through the use of streak camera techniques in which the time structure of the individual x-ray pulses are viewed as quasi-continuous sources with ∼100--200 picoseconds duration. Techniques for carrying out time-resolved scattering measurements on time scales varying from picoseconds to kiloseconds at present and proposed synchrotron sources are discussed and examples of time-resolved studies are cited. 17 refs., 8 figs

  15. A New Kind of Circular Polarization Leaky-Wave Antenna Based on Substrate Integrated Waveguide

    Directory of Open Access Journals (Sweden)

    Chong Zhang

    2015-01-01

    Full Text Available A new kind of circular polarization leaky-wave antenna with N-shaped slots cut in the upper side of substrate integrated waveguide (SIW is investigated and presented. The radiation pattern and polarization axial ratio of the leaky-wave antenna are studied. The results show that the width of N-shaped slots has significant effect on the circular polarization property of the antenna. By properly choosing structural parameters, the SIW based leaky-wave antenna can realize circular polarization with excellent axial ratio in 8 GHz satellite band.

  16. Time-resolved quantitative phosphoproteomics

    DEFF Research Database (Denmark)

    Verano-Braga, Thiago; Schwämmle, Veit; Sylvester, Marc

    2012-01-01

    proteins involved in the Ang-(1-7) signaling, we performed a mass spectrometry-based time-resolved quantitative phosphoproteome study of human aortic endothelial cells (HAEC) treated with Ang-(1-7). We identified 1288 unique phosphosites on 699 different proteins with 99% certainty of correct peptide...

  17. Time-resolved vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tokmakoff, Andrei [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Champion, Paul [Northeastern Univ., Boston, MA (United States); Heilweil, Edwin J. [National Inst. of Standards and Technology (NIST), Boulder, CO (United States); Nelson, Keith A. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Ziegler, Larry [Boston Univ., MA (United States)

    2009-05-14

    This document contains the Proceedings from the 14th International Conference on Time-Resolved Vibrational Spectroscopy, which was held in Meredith, NH from May 9-14, 2009. The study of molecular dynamics in chemical reaction and biological processes using time-resolved spectroscopy plays an important role in our understanding of energy conversion, storage, and utilization problems. Fundamental studies of chemical reactivity, molecular rearrangements, and charge transport are broadly supported by the DOE's Office of Science because of their role in the development of alternative energy sources, the understanding of biological energy conversion processes, the efficient utilization of existing energy resources, and the mitigation of reactive intermediates in radiation chemistry. In addition, time-resolved spectroscopy is central to all fiveof DOE's grand challenges for fundamental energy science. The Time-Resolved Vibrational Spectroscopy conference is organized biennially to bring the leaders in this field from around the globe together with young scientists to discuss the most recent scientific and technological advances. The latest technology in ultrafast infrared, Raman, and terahertz spectroscopy and the scientific advances that these methods enable were covered. Particular emphasis was placed on new experimental methods used to probe molecular dynamics in liquids, solids, interfaces, nanostructured materials, and biomolecules.

  18. Dual circularly polarized broadside beam antenna based on metasurfaces

    Science.gov (United States)

    Tellechea, A.; Caminita, F.; Martini, E.; Ederra, I.; Teniente, J.; Iriarte, J. C.; Gonzalo, R.; Maci, S.

    2018-02-01

    Design details of a Ku band metasurface (MTS) antenna with dual circularly polarized (CP) broadside radiation is shown in this work. By means of the surface impedance tensor modulation, synchronized propagation of two transversal magnetic (TM) and transverse electric (TE) surface waves (SWs) is ensured in the structure, which contribute to the radiation in broadside direction by the generation of a CP leaky wave. The structure is implemented by elliptical subwavelength metallic elements with a cross-shaped aperture in the center, printed on top of a thin substrate with high permittivity (AD1000 with a thickness of λ0/17). For the experimental validation, the MTS prototype has been excited employing an orthomode transducer composed by a metallic stepped septum inside an air-filled waveguide. Two orthogonal TE11 modes excited with ±90° phase shift in the feed couple with the TM and TE SWs supported by the MTS and generate RHCP or LHCP broadside beam. Experimental results are compared with the simulation predictions. Finally, conclusions are drawn.

  19. Last scattering, relic gravitons and the circular polarization of the CMB

    CERN Document Server

    Giovannini, Massimo

    2010-01-01

    The tensor contribution to the $V$-mode polarization induced by a magnetized plasma at last scattering vanishes exactly. Conversely a polarized background of relic gravitons cannot generate a $V$-mode polarization. The reported results suggest that, in the magnetized $\\Lambda$CDM paradigm, the dominant source of circular dichroism stems from the large-scale fluctuations of the spatial curvature.

  20. Attosecond polarization control in atomic RABBITT-like experiments assisted by a circularly polarized laser

    Science.gov (United States)

    Boll, D. I. R.; Fojón, O. A.

    2017-12-01

    We study theoretically the single ionization of noble gas atoms by the combined action of an attosecond pulse train with linear polarization and an assistant laser field with circular polarization. We employ a non-perturbative model that under certain approximations gives closed-form expressions for the angular distributions of photoelectrons. Interestingly, our model allow us to interpret these angular distributions as two-centre interferences where the orientation and the modulus of the separation vector between the virtual emitters is governed by the assistant laser field. Additionally, we show that such a configuration of light fields is similar to the polarization control technique, where both the attosecond pulse train and the assistant laser field have linear polarizations whose relative orientation may be controlled. Moreover, in order to compare our results with the available experimental data, we obtain analytical expressions for the cross sections integrated over the photoelectron emission angles. By means of these expressions, we define the ‘magic time’ as the delay for which the total cross sections for atomic targets exhibit the same functional form as the one of the monochromatic photoionization of diatomic molecular targets.

  1. Attosecond polarization control in atomic RABBITT-like experiments assisted by a circularly polarized laser

    International Nuclear Information System (INIS)

    Boll, D I R; Fojón, O A

    2017-01-01

    We study theoretically the single ionization of noble gas atoms by the combined action of an attosecond pulse train with linear polarization and an assistant laser field with circular polarization. We employ a non-perturbative model that under certain approximations gives closed-form expressions for the angular distributions of photoelectrons. Interestingly, our model allow us to interpret these angular distributions as two-centre interferences where the orientation and the modulus of the separation vector between the virtual emitters is governed by the assistant laser field. Additionally, we show that such a configuration of light fields is similar to the polarization control technique, where both the attosecond pulse train and the assistant laser field have linear polarizations whose relative orientation may be controlled. Moreover, in order to compare our results with the available experimental data, we obtain analytical expressions for the cross sections integrated over the photoelectron emission angles. By means of these expressions, we define the ‘magic time’ as the delay for which the total cross sections for atomic targets exhibit the same functional form as the one of the monochromatic photoionization of diatomic molecular targets. (paper)

  2. Circularly Polarized Microwave Antenna Element with Very Low Off-Axis Cross-Polarization

    Science.gov (United States)

    Greem. David; DuToit, Cornelis

    2013-01-01

    The goal of this work was to improve off-axis cross-polarization performance and ease of assembly of a circularly polarized microwave antenna element. To ease assembly, the initial design requirement of Hexweb support for the internal circuit part, as well as the radiating disks, was eliminated. There is a need for different plating techniques to improve soldering. It was also desirable to change the design to eliminate soldering as well as the need to use the Hexweb support. Thus, a technique was developed to build the feed without using solder, solving the lathing and soldering issue. Internal parts were strengthened by adding curvature to eliminate Hexweb support, and in the process, the new geometries of the internal parts opened the way for improving the off-axis cross-polarization performance as well. The radiating disks curvatures were increased for increased strength, but it was found that this also improved crosspolarization. Optimization of the curvatures leads to very low off-axis cross-polarization. The feed circuit was curved into a cylinder for improved strength, eliminating Hexweb support. An aperture coupling feed mechanism eliminated the need for feed pins to the disks, which would have required soldering. The aperture coupling technique also improves cross-polarization performance by effectively exciting the radiating disks very close to the antenna s central axis of symmetry. Because of the shape of the parts, it allowed for an all-aluminum design bolted together and assembled with no solder needed. The advantage of a solderless design is that the reliability is higher, with no single-point failure (solder), and no need for special plating techniques in order to solder the unit together. The shapes (curved or round) make for a more robust build without extra support materials, as well as improved offaxis cross-polarization.

  3. Linearly and circularly polarized laser photoinduced molecular order in azo dye doped polymer films

    Directory of Open Access Journals (Sweden)

    Saad Bendaoud

    2017-01-01

    Full Text Available Photo-induced behavior of Azo Disperse one (AZD1 doped Poly(Methyl MethAcrylate (PMMA using both linear and circular polarized light is studied. The anisotropy is not erased by the circular polarization light. The circular polarization light combined with relatively long lifetime of the cis state in azo dye doped polymers activate all transverse directions of the angular hole burning through the spot in the film inducing anisotropy. Under circular polarized light, there is no orientation perpendicularly to the helex described by the rotating electric field vector, trans molecules reorients in the propagation direction of the pump beam. The polarization state of the probe beam after propagation through the pumped spot depends strongly on the angle of incidence of both pump and probe beams on the input face. In the case where circular polarized pump and probe beams are under the same angle of incidence, the probe beam “sees” anisotropic film as if it is isotropic. Results of this work shows the possibility to reorient azobenzene-type molecules in two orthogonal directions using alternately linearly and circularly polarized beams.

  4. Linear Polarization, Circular Polarization, and Depolarization of Gamma-ray Bursts: A Simple Case of Jitter Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Jirong; Wang, Jiancheng, E-mail: jirongmao@mail.ynao.ac.cn [Yunnan Observatories, Chinese Academy of Sciences, 650011 Kunming, Yunnan Province (China)

    2017-04-01

    Linear and circular polarizations of gamma-ray bursts (GRBs) have been detected recently. We adopt a simplified model to investigate GRB polarization characteristics in this paper. A compressed two-dimensional turbulent slab containing stochastic magnetic fields is considered, and jitter radiation can produce the linear polarization under this special magnetic field topology. Turbulent Faraday rotation measure (RM) of this slab makes strong wavelength-dependent depolarization. The jitter photons can also scatter with those magnetic clumps inside the turbulent slab, and a nonzero variance of the Stokes parameter V can be generated. Furthermore, the linearly and circularly polarized photons in the optical and radio bands may suffer heavy absorptions from the slab. Thus we consider the polarized jitter radiation transfer processes. Finally, we compare our model results with the optical detections of GRB 091018, GRB 121024A, and GRB 131030A. We suggest simultaneous observations of GRB multi-wavelength polarization in the future.

  5. What makes single-helical metamaterials generate "pure" circularly polarized light?

    Science.gov (United States)

    Wu, Lin; Yang, ZhenYu; Zhao, Ming; Zhang, Peng; Lu, ZeQing; Yu, Yang; Li, ShengXi; Yuan, XiuHua

    2012-01-16

    Circular polarizers with left-handed helical metamaterials can transmit right-handed circularly polarized (RCP) light with few losses. But a certain amount of left-handed circularly polarized (LCP) light will occur in the transmitted light, which is the noise of the circular polarizer. Therefore, we defined the ratio of the RCP light intensity to the LCP light intensity as the signal-to-noise (S/N) ratio. In our previous work, it's found that circular polarizers with multi-helical metamaterials have two orders higher S/N ratios than that of single-helical metamaterials. However, it has been a great challenge to fabricate such multi-helical structures with micron or sub-micron feature sizes. Is it possible for the single-helical metamaterials to obtain equally high S/N ratios as the multi-helical ones? To answer this question, we systematically investigated the influences of structure parameters of single-helical metamaterials on the S/N ratios using the finite-different time-domain (FDTD) method. It was found that the single-helical metamaterials can also reach about 30dB S/N ratios, which are equal to the multi-helical ones. Furthermore, we explained the phenomenon by the antenna theory and optimized the performances of the single-helical circular polarizers.

  6. Circularly polarized light emission in scanning tunneling microscopy of magnetic systems

    International Nuclear Information System (INIS)

    Apell, S.P.; Penn, D.R.; Johansson, P.

    2000-01-01

    Light is produced when a scanning tunneling microscope is used to probe a metal surface. Recent experiments on cobalt utilizing a tungsten tip found that the light is circularly polarized; the sense of circular polarization depends on the direction of the sample magnetization, and the degree of polarization is of order 10%. This raises the possibility of constructing a magnetic microscope with very good spatial resolution. We present a theory of this effect for iron and cobalt and find a degree of polarization of order 0.1%. This is in disagreement with the experiments on cobalt as well as previous theoretical work which found order of magnitude agreement with the experimental results. However, a recent experiment on iron showed 0.0±2%. We predict that the use of a silver tip would increase the degree of circular polarization for a range of photon energies

  7. Forced Response of Polar Orthotropic Tapered Circular Plates Resting on Elastic Foundation

    Directory of Open Access Journals (Sweden)

    A. H. Ansari

    2016-01-01

    Full Text Available Forced axisymmetric response of polar orthotropic circular plates of linearly varying thickness resting on Winkler type of elastic foundation has been studied on the basis of classical plate theory. An approximate solution of problem has been obtained by Rayleigh Ritz method, which employs functions based upon the static deflection of polar orthotropic circular plates. The effect of transverse loadings has been studied for orthotropic circular plate resting on elastic foundation. The transverse deflections and bending moments are presented for various values of taper parameter, rigidity ratio, foundation parameter, and flexibility parameter under different types of loadings. A comparison of results with those available in literature shows an excellent agreement.

  8. Elimination of polarization degeneracy in circularly symmetric bianisotropic waveguides: a decoupled case.

    Science.gov (United States)

    Xu, Jing; Wu, Bingbing; Chen, Yuntian

    2015-05-04

    Mode properties of circularly symmetric waveguides with one special type of bianisotropy are studied using finite element approach. We find that the polarization degeneracy in circularly symmetric waveguides can be eliminated, by introducing intrinsic crossing coupling between electric and magnetic moments in the constituent units of the waveguide media. Breaking the polarization degeneracy in high order mode groups is also confirmed numerically. With the bianisotropic parameters chosen in this work, the x and y-polarized modes remain decoupled. Typically, the y-polarized modes remain completely unchanged, while the x-polarized modes are turned into leaky modes that are lossy along propagation direction. A perturbation model from coupled mode theory is developed to explain the results and shows excellent agreement. Such asymmetric behavior between different polarizations might be feasible and useful for developing compact polarizers in terahertz or mid-infrared regime.

  9. Time-resolved fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Gustavsson, Thomas; Mialocq, Jean-Claude

    2007-01-01

    This article addresses the evolution in time of light emitted by a molecular system after a brief photo-excitation. The authors first describe fluorescence from a photo-physical point of view and discuss the characterization of the excited state. Then, they explain some basic notions related to fluorescence characterization (lifetime and decays, quantum efficiency, so on). They present the different experimental methods and techniques currently used to study time-resolved fluorescence. They discuss basic notions of time resolution and spectral reconstruction. They briefly present some conventional methods: intensified Ccd cameras, photo-multipliers and photodiodes associated with a fast oscilloscope, and phase modulation. Other methods and techniques are more precisely presented: time-correlated single photon counting (principle, examples, and fluorescence lifetime imagery), streak camera (principle, examples), and optical methods like the Kerr optical effect (principle and examples) and fluorescence up-conversion (principle and theoretical considerations, examples of application)

  10. A New Dual Circularly Polarized Feed Employing a Dielectric Cylinder-Loaded Circular Waveguide Open End Fed by Crossed Dipoles

    Directory of Open Access Journals (Sweden)

    Jae-Hoon Bang

    2016-01-01

    Full Text Available This paper presents a new dual circularly polarized feed that provides good axial ratio over wide angles and low cross-polarized radiation in backward direction. A circular waveguide open end is fed with two orthogonally polarized waves in phase quadrature by a pair of printed crossed dipoles and a compact connectorized quadrature hybrid coupler. The waveguide aperture is loaded with a dielectric cylinder to reduce the cross-polarization beyond 90 degrees off the boresight. The fabricated feed has, at 5.5 GHz, 6.33-dBic copolarized gain, 3-dB beamwidth of 106°, 10-dB beamwidth of 195°, 3-dB axial ratio beamwidth of 215°, maximum cross-polarized gain of −21.4 dBic, and 27-dB port isolation. The reflection coefficient of the feed is less than −10 dB at 4.99–6.09 GHz.

  11. Circular polarization of radio emission from air showers in thunderstorm conditions

    NARCIS (Netherlands)

    Trinh, T. N. G.; Scholten, O.; Bonardi, A.; Buitink, S.; Corstanje, A.; Ebert, U.; Enriquez, J. E.; Falcke, H.; Hörandel, J. R.; Mitra, P.; Mulrey, K.; Nelles, A.; Thoudam, S.; Rachen, J. P.; Rossetto, L.; Rutjes, C.; Schellart, P.; ter Veen, S.; Winchen, T.

    2017-01-01

    We present measured radio emission from cosmic-ray-induced air showers under thunderstorm conditions. We observe for these events large differences in intensity, linear polarization and circular polarization from the events measured under fair-weather conditions. This can be explained by the effects

  12. Imaging linear and circular polarization features in leaves with complete Mueller matrix polarimetry.

    Science.gov (United States)

    Patty, C H Lucas; Luo, David A; Snik, Frans; Ariese, Freek; Buma, Wybren Jan; Ten Kate, Inge Loes; van Spanning, Rob J M; Sparks, William B; Germer, Thomas A; Garab, Győző; Kudenov, Michael W

    2018-03-09

    Spectropolarimetry of intact plant leaves allows to probe the molecular architecture of vegetation photosynthesis in a non-invasive and non-destructive way and, as such, can offer a wealth of physiological information. In addition to the molecular signals due to the photosynthetic machinery, the cell structure and its arrangement within a leaf can create and modify polarization signals. Using Mueller matrix polarimetry with rotating retarder modulation, we have visualized spatial variations in polarization in transmission around the chlorophyll a absorbance band from 650 nm to 710 nm. We show linear and circular polarization measurements of maple leaves and cultivated maize leaves and discuss the corresponding Mueller matrices and the Mueller matrix decompositions, which show distinct features in diattenuation, polarizance, retardance and depolarization. Importantly, while normal leaf tissue shows a typical split signal with both a negative and a positive peak in the induced fractional circular polarization and circular dichroism, the signals close to the veins only display a negative band. The results are similar to the negative band as reported earlier for single macrodomains. We discuss the possible role of the chloroplast orientation around the veins as a cause of this phenomenon. Systematic artefacts are ruled out as three independent measurements by different instruments gave similar results. These results provide better insight into circular polarization measurements on whole leaves and options for vegetation remote sensing using circular polarization. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

  13. Design of Multilevel Sequential Rotation Feeding Networks Used for Circularly Polarized Microstrip Antenna Arrays

    Directory of Open Access Journals (Sweden)

    Aixin Chen

    2012-01-01

    Full Text Available Sequential rotation feeding networks can significantly improve performance of the circularly polarized microstrip antenna array. In this paper, single, double, and multiple series-parallel sequential rotation feeding networks are examined. Compared with conventional parallel feeding structures, these multilevel feeding techniques present reduction of loss, increase of bandwidth, and improvement of radiation pattern and polarization purity. By using corner-truncated square patch as the array element and adopting appropriate level of sequential rotation series-parallel feeding structures as feeding networks, microstrip arrays can generate excellent circular polarization (CP over a relatively wide frequency band. They can find wide applications in phased array radar and satellite communication systems.

  14. Electrical access to critical coupling of circularly polarized waves in graphene chiral metamaterials.

    Science.gov (United States)

    Kim, Teun-Teun; Oh, Sang Soon; Kim, Hyeon-Don; Park, Hyun Sung; Hess, Ortwin; Min, Bumki; Zhang, Shuang

    2017-09-01

    Active control of polarization states of electromagnetic waves is highly desirable because of its diverse applications in information processing, telecommunications, and spectroscopy. However, despite the recent advances using artificial materials, most active polarization control schemes require optical stimuli necessitating complex optical setups. We experimentally demonstrate an alternative-direct electrical tuning of the polarization state of terahertz waves. Combining a chiral metamaterial with a gated single-layer sheet of graphene, we show that transmission of a terahertz wave with one circular polarization can be electrically controlled without affecting that of the other circular polarization, leading to large-intensity modulation depths (>99%) with a low gate voltage. This effective control of polarization is made possible by the full accessibility of three coupling regimes, that is, underdamped, critically damped, and overdamped regimes by electrical control of the graphene properties.

  15. Four-wave mixing using polarization grating induced thermal grating in liquids exhibiting circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, J.A.; Tong, W.G. [San Diego State Univ., CA (United States). Dept. of Chemistry; Chandler, D.W.; Rahn, L.A. [Sandia National Lab., Livermore, CA (United States). Combustion Research Facility

    1995-04-01

    A novel four-wave mixing technique for the detection of circular dichroism in optically active liquid samples is demonstrated. When two cross-polarized laser beams are crossed at a small angle in a circular dichroic liquid a weak thermal grating is produced with a phase depending on the sign of the circular dichroism. The authors show that the polarization of one of the beams can be modified to allow coherent interference with an intensity-grating induced thermal grating. A probe beam scattering from the composite grating results in a signal that reveals the sign and magnitude of the circular dichroism. The use of this technique to optimize the signal-to-noise ratio in the presence of scattered light and laser intensity noise is discussed.

  16. Atomistic modeling of IR action spectra under circularly polarized electromagnetic fields: toward action VCD spectra.

    Science.gov (United States)

    Calvo, Florent

    2015-03-01

    The nonlinear response and dissociation propensity of an isolated chiral molecule, camphor, to a circularly polarized infrared laser pulse was simulated by molecular dynamics as a function of the excitation wavelength. The results indicate similarities with linear absorption spectra, but also differences that are ascribable to dynamical anharmonic effects. Comparing the responses between left- and right-circularly polarized pulses in terms of dissociation probabilities, or equivalently between R- and S-camphor to a similarly polarized pulse, we find significant differences for the fingerprint C = O amide mode, with a sensitivity that could be sufficient to possibly enable vibrational circular dichroism as an action technique for probing molecular chirality and absolute conformations in the gas phase. © 2015 Wiley Periodicals, Inc.

  17. Circular polarization of light by planet Mercury and enantiomorphism of its surface minerals.

    Science.gov (United States)

    Meierhenrich, Uwe J; Thiemann, Wolfram H P; Barbier, Bernard; Brack, André; Alcaraz, Christian; Nahon, Laurent; Wolstencroft, Ray

    2002-04-01

    Different mechanisms for the generation of circular polarization by the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For BepiColombo, the ESA cornerstone mission 5 to Mercury, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter, capable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE.

  18. Amplification of Circularly Polarized Luminescence through Triplet-Triplet Annihilation-Based Photon Upconversion.

    Science.gov (United States)

    Han, Jianlei; Duan, Pengfei; Li, Xianggao; Liu, Minghua

    2017-07-26

    Amplification of circularly polarized luminescence (CPL) is demonstrated in a triplet-triplet annihilation-based photon upconversion (TTA-UC) system. When chiral binaphthyldiamine acceptors are sensitized with an achiral Pt(II) octaethylporphine (PtOEP) in solution, upconverted circularly polarized luminescence (UC-CPL) were observed for the first time, in which the positive or negative circularly polarized emission could be obtained respectively, following the molecular chirality of the acceptors (R/S). More interestingly, one order of magnitude amplification of the dissymmetry factor g lum in UC-CPL was obtained in comparison with the normal promoted CPL. The multistep photophysical process of TTA-UC including triplet-triplet energy transfer (TTET) and triplet-triplet annihilation (TTA) have been suggested to enhance the UC-CPL, which provided a new strategy to design CPL materials with a higher dissymmetry factor.

  19. Magnetic Field Generation through Angular Momentum Exchange between Circularly Polarized Radiation and Charged Particles

    CERN Document Server

    Shvets, G

    2002-01-01

    The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation.

  20. Magnetic Field Generation through Angular Momentum Exchange between Circularly Polarized Radiation and Charged Particles

    International Nuclear Information System (INIS)

    G. Shvets; N.J. Fisch; J.-M. Rax

    2002-01-01

    The interaction between circularly polarized (CP) radiation and charged particles can lead to generation of magnetic field through an inverse Faraday effect. The spin of the circularly polarized electromagnetic wave can be converted into the angular momentum of the charged particles so long as there is dissipation. We demonstrate this by considering two mechanisms of angular momentum absorption relevant for laser-plasma interactions: electron-ion collisions and ionization. The precise dissipative mechanism, however, plays a role in determining the efficiency of the magnetic field generation

  1. Circular polarization in the optical afterglow of GRB 121024A

    DEFF Research Database (Denmark)

    Wiersema, K.; Covino, S.; Toma, K.

    2014-01-01

    Gamma-ray bursts (GRBs) are most probably powered by collimated relativistic outflows (jets) from accreting black holes at cosmological distances. Bright afterglows are produced when the outflow collides with the ambient medium. Afterglow polarization directly probes the magnetic properties of th...

  2. Time-resolved fluorescence analysis of the mobile flavin cofactor

    Indian Academy of Sciences (India)

    Conformational heterogeneity of the FAD cofactor in -hydroxybenzoate hydroxylase (PHBH) was investigated with time-resolved polarized flavin fluorescence. For binary enzyme/substrate (analogue) complexes of wild-type PHBH and Tyr222 mutants, crystallographic studies have revealed two distinct flavin conformations ...

  3. Applications of circularly polarized photons at the ALS with a bend magnet source

    Energy Technology Data Exchange (ETDEWEB)

    1992-02-01

    The purpose of this workshop is to focus attention on, and to stimulate the scientific exploitation of, the natural polarization properties of bend-magnet synchrotron radiation at the ALS -- for research in biology, materials science, physics, and chemistry. The topics include: The Advanced Light Source; Magnetic Circular Dichroism and Differential Scattering on Biomolecules; Tests of Fundamental Symmetries; High {Tc} Superconductivity; Photoemission from Magnetic and Non-magnetic Solids; Studies of Highly Correlated Systems; and Instrumentation for Photon Transport and Polarization Measurements.

  4. Photoemission of Bi_{2}Se_{3} with Circularly Polarized Light: Probe of Spin Polarization or Means for Spin Manipulation?

    Directory of Open Access Journals (Sweden)

    J. Sánchez-Barriga

    2014-03-01

    Full Text Available Topological insulators are characterized by Dirac-cone surface states with electron spins locked perpendicular to their linear momenta. Recent theoretical and experimental work implied that this specific spin texture should enable control of photoelectron spins by circularly polarized light. However, these reports questioned the so far accepted interpretation of spin-resolved photoelectron spectroscopy. We solve this puzzle and show that vacuum ultraviolet photons (50–70 eV with linear or circular polarization indeed probe the initial-state spin texture of Bi_{2}Se_{3} while circularly polarized 6-eV low-energy photons flip the electron spins out of plane and reverse their spin polarization, with its sign determined by the light helicity. Our photoemission calculations, taking into account the interplay between the varying probing depth, dipole-selection rules, and spin-dependent scattering effects involving initial and final states, explain these findings and reveal proper conditions for light-induced spin manipulation. Our results pave the way for future applications of topological insulators in optospintronic devices.

  5. Construction and performance of BL28 of the Photon Factory for circularly polarized synchrotron radiation

    International Nuclear Information System (INIS)

    Kagoshima, Y.; Muto, S.; Miyahara, T.; Koide, T.; Yamamoto, S.; Kitamura, H.

    1992-01-01

    A branch beamline, BL28A, has been constructed for the application of circularly polarized vacuum ultraviolet radiation. The radiation can be obtained in the helical undulator operation mode of an insertion device, EMPW number-sign 28, which is also cut for elliptically polarized hard x-ray radiation. T first harmonic of the helical undulator radiation can be tuned from 40 to 350 eV with its corresponding K value from 3 to 0.2. A monochromator working basically with constant deviation optics was installed, and has started its operation. A circularly polarized flux of ∼10 10 photons/s has been achieved with energy resolution of around 500--1000 at the first harmonic peak. The circular polarization after the monochromator was estimated to be higher than 70% by comparing theory and experiment on the magnetic circular dichroism of nickel films in the 3p-3d excitation region. The design philosophy of the beamline and recent results on the performance tests are presented

  6. Circular polarization with crossed-planar undulators in high-gain FELs

    CERN Document Server

    Kim, K J K J

    2000-01-01

    We propose a crossed undulator configuration for a high-gain free-electron laser to allow versatile polarization control. This configuration consists of a long (saturation length) planar undulator, a dispersive section, and a short (a few gain lengths) planar undulator oriented perpendicular to the first one. In the first undulator, a radiation component linearly polarized in the x-direction is amplified to saturation. In the second undulator, the x-polarized component propagates freely, while a new component, polarized in the y-direction, is generated and reaches saturation in a few gain lengths. By adjusting the strength of the dispersive section, the relative phase of two radiation components can be adjusted to obtain a suitable polarization for the total radiation field, including the circular polarization. The operating principle of the high-gain crossed undulator, which is quite different from that of the crossed undulator for spontaneous radiation, is illustrated in terms of 1-D FEL theory.

  7. Circular polarization switching and bistability in an optically injected 1300 nm spin-vertical cavity surface emitting laser

    Energy Technology Data Exchange (ETDEWEB)

    Alharthi, S. S., E-mail: ssmalh@essex.ac.uk; Henning, I. D.; Adams, M. J. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Hurtado, A. [School of Computer Science and Electronic Engineering, University of Essex, Wivenhoe Park, Colchester CO4 3SQ (United Kingdom); Institute of Photonics, Physics Department, University of Strathclyde, Wolfson Centre, 106 Rottenrow East, Glasgow G4 0NW, Scotland (United Kingdom); Korpijarvi, V.-M.; Guina, M. [Optoelectronics Research Centre (ORC), Tampere University of Technology, P.O. Box 692, FIN-33101 Tampere (Finland)

    2015-01-12

    We report the experimental observation of circular polarization switching (PS) and polarization bistability (PB) in a 1300 nm dilute nitride spin-vertical cavity surface emitting laser (VCSEL). We demonstrate that the circularly polarized optical signal at 1300 nm can gradually or abruptly switch the polarization ellipticity of the spin-VCSEL from right-to-left circular polarization and vice versa. Moreover, different forms of PS and PB between right- and left-circular polarizations are observed by controlling the injection strength and the initial wavelength detuning. These results obtained at the telecom wavelength of 1300 nm open the door for novel uses of spin-VCSELs in polarization sensitive applications in future optical systems.

  8. High-order-harmonic generation in benzene with linearly and circularly polarized laser pulses

    Science.gov (United States)

    Wardlow, Abigail; Dundas, Daniel

    2016-02-01

    High-order-harmonic generation in benzene is studied using a mixed quantum-classical approach in which the electrons are described using time-dependent density-functional theory while the ions move classically. The interaction with both linearly and circularly polarized infrared (λ =800 nm) laser pulses of duration of ten cycles (26.7 fs) is considered. The effect of allowing the ions to move is investigated as is the effect of including self-interaction corrections to the exchange-correlation functional. Our results for circularly polarized pulses are compared with previous calculations in which the ions were kept fixed and self-interaction corrections were not included, while our results for linearly polarized pulses are compared with both previous calculations and experiment. We find that even for the short-duration pulses considered here, the ionic motion greatly influences the harmonic spectra. While ionization and ionic displacements are greatest when linearly polarized pulses are used, the response to circularly polarized pulses is almost comparable, in agreement with previous experimental results.

  9. Circular Polarization of Light By Planet Mercury and Enantiomorphism of Its Surface Minerals

    Science.gov (United States)

    Meierhenrich, U. J.; Thiemann, W. H.-P.; Barbier, B.; Brack, A.; Nahon, L.; Alcaraz, C.; Wolstencroft, R.

    Different mechanisms for the generation of circular polarization on the surface of planets and satellites are described. The observed values for Venus, the Moon, Mars, and Jupiter obtained by photo-polarimetric measurements with Earth based telescopes, showed accordance with theory. However, for planet Mercury asymmetric parameters in the circular polarization were measured that do not fit with calculations. For Bepi- Colombo, we propose to investigate this phenomenon using a concept which includes two instruments. The first instrument is a high-resolution optical polarimeter,[1,2] ca- pable to determine and map the circular polarization by remote scanning of Mercury's surface from the Mercury Planetary Orbiter MPO. The second instrument is an in situ sensor for the detection of the enantiomorphism of surface crystals and minerals, proposed to be included in the Mercury Lander MSE. [1] C. Alcaraz, R. Thissen, M. Compin, A. Jolly, M. Drescher, L. Nahon: First po- larization measurements of Ophelie: a versatile polarization VUV undulator at Super- Aco. SPIE 3773 (1999), 250-261. [2] C. Alcaraz, J.L. Marlats, D. Nether, B. Pilette, L. Nahon: A dedicated precise polarimeter for measurement of VUV versatile photon polarizations, Applied Optics, manuscript under preparation.

  10. Analytical treatment of particle motion in circularly polarized slab-mode wave fields

    Science.gov (United States)

    Schreiner, Cedric; Vainio, Rami; Spanier, Felix

    2018-02-01

    Wave-particle interaction is a key process in particle diffusion in collisionless plasmas. We look into the interaction of single plasma waves with individual particles and discuss under which circumstances this is a chaotic process, leading to diffusion. We derive the equations of motion for a particle in the fields of a magnetostatic, circularly polarized, monochromatic wave and show that no chaotic particle motion can arise under such circumstances. A novel and exact analytic solution for the equations is presented. Additional plasma waves lead to a breakdown of the analytic solution and chaotic particle trajectories become possible. We demonstrate this effect by considering a linearly polarized, monochromatic wave, which can be seen as the superposition of two circularly polarized waves. Test particle simulations are provided to illustrate and expand our analytical considerations.

  11. Inertial displacement of a domain wall excited by ultra-short circularly polarized laser pulses

    Science.gov (United States)

    Janda, T.; Roy, P. E.; Otxoa, R. M.; Šobáň, Z.; Ramsay, A.; Irvine, A. C.; Trojanek, F.; Surýnek, M.; Campion, R. P.; Gallagher, B. L.; Němec, P.; Jungwirth, T.; Wunderlich, J.

    2017-05-01

    Domain wall motion driven by ultra-short laser pulses is a pre-requisite for envisaged low-power spintronics combining storage of information in magnetoelectronic devices with high speed and long distance transmission of information encoded in circularly polarized light. Here we demonstrate the conversion of the circular polarization of incident femtosecond laser pulses into inertial displacement of a domain wall in a ferromagnetic semiconductor. In our study, we combine electrical measurements and magneto-optical imaging of the domain wall displacement with micromagnetic simulations. The optical spin-transfer torque acts over a picosecond recombination time of the spin-polarized photo-carriers that only leads to a deformation of the initial domain wall structure. We show that subsequent depinning and micrometre-distance displacement without an applied magnetic field or any other external stimuli can only occur due to the inertia of the domain wall.

  12. Quantitative assessment of spinal cord injury using circularly polarized coherent anti-Stokes Raman scattering microscopy

    Science.gov (United States)

    Bae, Kideog; Zheng, Wei; Huang, Zhiwei

    2017-08-01

    We report the quantitative assessment of spinal cord injury using the circularly polarized coherent anti-Stokes Raman scattering (CP-CARS) technique together with Stokes parameters in the Poincaré sphere. The pump and Stokes excitation beams are circularly polarized to suppress both the linear polarization-dependent artifacts and the nonresonant background of tissue CARS imaging, enabling quantitative CP-CARS image analysis. This study shows that CP-CARS imaging uncovers significantly increased phase retardance of injured spinal cord tissue as compared to normal tissue, suggesting that CP-CARS is an appealing label-free imaging tool for determining the degree of tissue phase retardance, which could serve as a unique diagnostic parameter associated with nervous tissue injury.

  13. Circular Polarizations of Gravitational Waves from Core-Collapse Supernovae: A Clear Indication of Rapid Rotation.

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Nakamura, Ko; Yamada, Shoichi

    2016-04-15

    We propose to employ the circular polarization of gravitational waves emitted by core-collapse supernovae as an unequivocal indication of rapid rotation deep in their cores just prior to collapse. It has been demonstrated by three dimensional simulations that nonaxisymmetric accretion flows may develop spontaneously via hydrodynamical instabilities in the postbounce cores. It is not surprising, then, that the gravitational waves emitted by such fluid motions are circularly polarized. We show, in this Letter, that a network of the second generation detectors of gravitational waves worldwide may be able to detect such polarizations up to the opposite side of the Galaxy as long as the rotation period of the core is shorter than a few seconds prior to collapse.

  14. Unidirectional evanescent-wave coupling from circularly polarized electric and magnetic dipoles: An angular spectrum approach

    Science.gov (United States)

    Picardi, Michela F.; Manjavacas, Alejandro; Zayats, Anatoly V.; Rodríguez-Fortuño, Francisco J.

    2017-06-01

    Unidirectional evanescent-wave coupling from circularly polarized dipole sources is one of the most striking types of evidence of spin-orbit interactions of light and an inherent property of circularly polarized dipoles. Polarization handedness self-determines propagation direction of guided modes. In this paper, we compare two different approaches currently used to describe this phenomenon: the first requires the evaluation of the coupling amplitude between dipole and waveguide modes, while the second is based on the calculation of the angular spectrum of the dipole. We present an analytical expression of the angular spectrum of dipole radiation, unifying the description for both electric and magnetic dipoles. The symmetries unraveled by the implemented formalism show the existence of specific terms in the dipole spectrum which can be recognized as being directly responsible for directional evanescent-wave coupling. This provides a versatile tool for both a comprehensive understanding of the phenomenon and a fully controllable engineering of directionality of guided modes.

  15. Time resolved spectroscopic studies on some nanophosphors

    Indian Academy of Sciences (India)

    Wintec

    Abstract. Time resolved spectroscopy is an important tool for studying photophysical processes in phosphors. Present work investigates the steady state and time resolved photoluminescence (PL) spectroscopic characteristics of ZnS, ZnO and (Zn, Mg)O nanophosphors both in powder as well as thin film form.

  16. Competition of circularly polarized laser modes in the modulation instability of hot magnetoplasma

    International Nuclear Information System (INIS)

    Sepehri Javan, N.

    2013-01-01

    The present study is aimed to investigate the problem of modulation instability of an intense laser beam in the hot magnetized plasma. The propagation of intense circularly polarized laser beam along the external magnetic field is considered using a relativistic fluid model. The nonlinear equation describing the interaction of laser pulse with magnetized hot plasma is derived in the quasi-neutral approximation, which is valid for hot plasma. Nonlinear dispersion equation for hot plasma is obtained. For left- and right-hand polarizations, the growth rate of instability is achieved and the effect of temperature, external magnetic field, and kind of polarization on the growth rate is considered. It is observed that for the right-hand polarization, increase of magnetic field leads to the increasing of growth rate. Also for the left-hand polarization, increase of magnetic field inversely causes decrease of the growth rate.

  17. Scanning differential polarization microscope: Its use to image linear and circular differential scattering

    International Nuclear Information System (INIS)

    Mickols, W.; Maestre, M.F.

    1988-01-01

    A differential polarization microscope that couples the sensitivity of single-beam measurement of circular dichroism and circular differential scattering with the simultaneous measurement of linear dichroism and linear differential scattering has been developed. The microscope uses a scanning microscope stage and single-point illumination to give the very shallow depth of field found in confocal microscopy. This microscope can operate in the confocal mode as well as in the near confocal condition that can allow one to program the coherence and spatial resolution of the microscope. This microscope has been used to study the change in the structure of chromatin during the development of sperm in Drosophila

  18. NEAR-INFRARED IMAGING POLARIMETRY OF GGD 27: CIRCULAR POLARIZATION AND MAGNETIC FIELD STRUCTURES

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Jungmi; Tamura, Motohide [Department of Astronomy, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Hough, James H. [University of Hertfordshire, Hatfield, Herts AL10 9AB (United Kingdom); Nagata, Tetsuya [Kyoto University, Sakyo-ku, Kyoto 606-8502 (Japan); Kusakabe, Nobuhiko [National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo 181-8588 (Japan); Saito, Hiro, E-mail: jungmi.kwon@astron.s.u-tokyo.ac.jp [Department of Astronomy and Earth Sciences, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan)

    2016-06-20

    Near-infrared imaging polarimetry in the J , H , and K{sub s} bands was carried out for GGD 27 in the dark cloud Lynds 291. Details of an infrared reflection nebula associated with the optical nebulosity GGD 27 and the infrared nebula GGD 27 IRS are presented. Aperture photometry of 1263 point-like sources, detected in all three bands, was used to classify them based on a color–color diagram, and the linear polarization of several hundred sources was determined, with the latter used to map the magnetic field structure around GGD 27. This field, around GGD 27 IRS, appears to be associated with the extended CO outflow of IRAS 18162–2048; however, there are partly distorted or bent components in the field. The Chandrasekhar–Fermi method gives an estimate of the magnetic field strength as ∼90 μ G. A region associated with GGD 27 IRS is discovered to have a circular polarization in the range of ∼2%–11% in the K{sub s} band. The circular polarization has an asymmetric positive/negative pattern and extends out to ∼ 120″ or 1.0 pc. The circular and linear polarization patterns are explained as resulting from a combination of dense inner and fainter outer lobes, suggesting episodic outflow.

  19. Nonlinear optical responses to circularly polarized lights of the surface state of a topological insulator

    Science.gov (United States)

    Misawa, Tetsuro; Yokoyama, Takehito; Murakami, Shuichi

    2012-02-01

    Recent photoelectron spectroscopy experiments have revealed the presence of the Dirac cone on the surface of the topological insulator and its spin-splitting due to the spin-orbit interaction. In general, on spin-orbit coupled systems, electric fields induce spin polarizations as linear and nonlinear responses. Here we investigate the inverse Faraday effect on the surface of the topological insulator. The inverse Faraday effect is a non-linear optical effect where a circularly polarized light induces a dc spin polarization. We employ the Keldysh Green's function method to calculate the induced spin polarization and discuss its frequency dependence. In particular, in the low frequency limit, our analytical result gives the spin polarization proportional to the frequency and the square of the lifetime. As for the finite frequency regime, we employ numerical methods to discuss the resonance due to interband transitions. We also discuss the photogalvanic effect, where an illumination of a circular polarized light generates the dc charge current. Lastly, we evaluate those quantities with realistic parameters.[4pt] [1] T. Misawa, T. Yokoyama, S. Murakami, Phys. Rev. B84, 165407 (2011).

  20. Light trapping and circularly polarization at a Dirac point in 2D plasma photonic crystals

    Science.gov (United States)

    Li, Qian; Hu, Lei; Mao, Qiuping; Jiang, Haiming; Hu, Zhijia; Xie, Kang; Wei, Zhang

    2018-03-01

    Light trapping at the Dirac point in 2D plasma photonic crystal has been obtained. The new localized mode, Dirac mode, is attributable to neither photonic bandgap nor total internal reflection. It exhibits a unique algebraic profile and possesses a high-Q factor resonator of about 105. The Dirac point could be modulated by tuning the filling factor, plasma frequency and plasma cyclotron frequency, respectively. When a magnetic field parallel to the wave vector is applied, Dirac modes for right circularly polarized and left circularly polarized waves could be obtained at different frequencies, and the Q factor could be tuned. This property will add more controllability and flexibility to the design and modulation of novel photonic devices. It is also valuable for the possibilities of Dirac modes in photonic crystal containing other kinds of metamaterials.

  1. Design of CPW fed printed slot antenna with circular polarization for UWB application

    Science.gov (United States)

    Choudhary, N.; Tiwari, A.; Jangid, K. G.; Sharma, B. R.; Saini, J. S.; Kulhar, V. S.; Bhatnagar, D.

    2016-03-01

    This paper reports the design and performance of a CPW-fed circularized polarized elliptical slot antenna for UWB (ultra wide band) applications. The circular polarization is achieved by applying triangular stubs in the ground plane. The overall volume of this antenna is 40mm × 40 mm × 1.59 mm. The proposed antenna is simulated by applying CST Microwave Studio simulator. This elliptical patch slot antenna provides broad impedance bandwidth (3.1GHz to 10.6 GHz) with maximum gain 4.31dB at 4.45GHz. The simulated 3-dB axial ratio bandwidth is close to 2.51GHz (from 4.76GHz to 7.27GHz) which is 41.76% with respect to the central frequency 6.01GHz.

  2. Multiphoton ionization of the hydrogen atom by a circularly polarized electromagnetic field

    International Nuclear Information System (INIS)

    Prepelitsa, O.B.

    1999-01-01

    This paper examines the multiphoton ionization of the ground state of the hydrogen atom in the field of a circularly polarized intense electromagnetic wave. To describe the states of photoelectrons, quasiclassical wave functions are introduced that partially allow for the effect of an intense electromagnetic wave and that of the Coulomb potential. Expressions are derived for the angular and energy distributions of photoelectrons with energies much lower than the ionization potential of an unperturbed atom. It is found that, due to allowance for the Coulomb potential in the wave function of the final electron states, the transition probability near the ionization threshold tends to a finite value. In addition, the well-known selection rules for multiphoton transitions in a circularly polarized electromagnetic field are derived in a natural way. Finally, the results are compared with those obtained in the Keldysh-Faisal-Reiss approximation

  3. High-flux normal incidence monochromator for circularly polarized synchrotron radiation

    International Nuclear Information System (INIS)

    Schaefers, F.; Peatman, W.; Eyers, A.; Heckenkamp, C.; Schoenhense, G.; Heinzmann, U.

    1986-01-01

    A 6.5-m normal incidence monochromator installed at the storage ring BESSY, which is optimized for a high throughput of circularly polarized off-plane radiation at moderate resolution is described. The monochromator employs two exit slits and is specially designed and used for low-signal experiments such as spin- and angle-resolved photoelectron spectroscopy on solids, adsorbates, free atoms, and molecules. The Monk--Gillieson mounting (plane grating in a convergent light beam) allows for large apertures with relatively little astigmatism. With two gratings, a flux of more than 10 11 photons s -1 bandwidth -1 (0.2--0.5 nm) with a circular polarization of more than 90% in the wavelength range from 35 to 675 nm is achieved

  4. Circularly Polarized Antenna Array Fed by Air-Bridge Free CPW-Slotline Network

    Directory of Open Access Journals (Sweden)

    Yilin Liu

    2017-01-01

    Full Text Available A novel design of 1×2 and 2×2 circularly polarized (CP microstrip patch antenna arrays is presented in this paper. The two CP antenna arrays are fed by sequentially rotated coplanar waveguide (CPW to slotline networks and are processed on 1 mm thick single-layer FR4 substrates. Both of the two arrays are low-profile and lightweight. An air-bridge free CPW-slotline power splitter is appropriately designed to form the feeding networks and realize the two CP antenna arrays. The mechanism of circular polarization in this design is explained. The simulated and measured impedance bandwidths as well as the 3 dB axial ratio bandwidths and the radiation patterns of the two proposed antenna arrays are presented. This proposed design can be easily extended to form a larger plane array with good performance owing to its simple structure.

  5. In-line phase retarder and polarimeter for conversion of linear to circular polarization

    Energy Technology Data Exchange (ETDEWEB)

    Kortright, J.B.; Smith, N.V.; Denlinger, J.D. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    An in-line polarimeter including phase retarder and linear polarizer was designed and commissioned on undulator beamline 7.0 for the purpose of converting linear to circular polarization for experiments downstream. In commissioning studies, Mo/Si multilayers at 95 eV were used both as the upstream, freestanding phase retarder and the downstream linear polarized. The polarization properties of the phase retarder were characterized by direct polarimetry and by collecting MCD spectra in photoemission from Gd and other magnetic surfaces. The resonant birefringence of transmission multilayers results from differing distributions of s- and p-component wave fields in the multilayer when operating near a structural (Bragg) interference condition. The resulting phase retardation is especially strong when the interference is at or near the Brewster angle, which is roughly 45{degrees} in the EUV and soft x-ray ranges.

  6. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    International Nuclear Information System (INIS)

    Strempfer, J.; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H.; Bouchenoire, L.

    2016-01-01

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L 3 absorption edges are presented.

  7. Fast helicity switching of x-ray circular polarization at beamline P09 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Strempfer, J., E-mail: Joerg.Strempfer@desy.de; Mardegan, J. R. L.; Francoual, S.; Veiga, L. S. I.; Spitzbart, T.; Zink, H. [Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22603 Hamburg (Germany); Bouchenoire, L. [XMaS, ESRF, 6 rue Jules Horowitz, BP220, Grenoble 38043 (France); Department of Physics, University of Liverpool, Liverpool, L69 7ZE (United Kingdom)

    2016-07-27

    At the resonant scattering and diffraction beamline P09 at PETRA III/DESY, polarization manipulation in the X-ray energy range 3-13 keV is possible using wave-plates. Recently, fast flipping of circular polarization helicity using the Raspberry Pi controlled FPGA (PiLC) device developed at DESY and dedicated piezo-electric flippers has been commissioned. Functionality of the PiLC for XMCD and first XMCD measurements at the Fe K-and Dy-L{sub 3} absorption edges are presented.

  8. Dynamical model of coherent circularly polarized optical pulse interactions with two-level quantum systems

    International Nuclear Information System (INIS)

    Slavcheva, G.; Hess, O.

    2005-01-01

    We propose and develop a method for theoretical description of circularly (elliptically) polarized optical pulse resonant coherent interactions with two-level atoms. The method is based on the time-evolution equations of a two-level quantum system in the presence of a time-dependent dipole perturbation for electric dipole transitions between states with total angular-momentum projection difference (ΔJ z =±1) excited by a circularly polarized electromagnetic field [Feynman et al., J. Appl. Phys. 28, 49 (1957)]. The adopted real-vector representation approach allows for coupling with the vectorial Maxwell's equations for the optical wave propagation and thus the resulting Maxwell pseudospin equations can be numerically solved in the time domain without any approximations. The model permits a more exact study of the ultrafast coherent pulse propagation effects taking into account the vector nature of the electromagnetic field and hence the polarization state of the optical excitation. We demonstrate self-induced transparency effects and formation of polarized solitons. The model represents a qualitative extension of the well-known optical Maxwell-Bloch equations valid for linearly polarized light and a tool for studying coherent quantum control mechanisms

  9. Ultra-wideband circular-polarization converter with micro-split Jerusalem-cross metasurfaces

    Science.gov (United States)

    Gao, Xi; Yu, Xing-Yang; Cao, Wei-Ping; Jiang, Yan-Nan; Yu, Xin-Hua

    2016-12-01

    An ultrathin micro-split Jerusalem-cross metasurface is proposed in this paper, which can efficiently convert the linear polarization of electromagnetic (EM) wave into the circular polarization in ultra-wideband. By symmetrically employing two micro-splits on the horizontal arm (in the x direction) of the Jerusalem-cross structure, the bandwidth of the proposed device is significantly extended. Both simulated and experimental results show that the proposed metasurface is able to convert linearly polarized waves into circularly polarized waves in a frequency range from 12.4 GHz to 21 GHz, with an axis ratio better than 1 dB. The simulated results also show that such a broadband and high-performance are maintained over a wide range of incident angle. The presented polarization converter can be used in a number of areas, such as spectroscopy and wireless communications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61461016 and 61661012), the Natural Science Foundation of Guangxi Zhuang Autonomous Region, China (Grant Nos. 2014GXNSFAA118366, 2014GXNSFAA118283, and 2015jjBB7002), and the Innovation Project of Graduate Education of Guilin University of Electronic Technology, China (Grant No. 2016YJCX82).

  10. Periodic array of quantum rings strongly coupled to circularly polarized light as a topological insulator

    Science.gov (United States)

    Kozin, V. K.; Iorsh, I. V.; Kibis, O. V.; Shelykh, I. A.

    2018-01-01

    We demonstrate theoretically that a strong high-frequency circularly polarized electromagnetic field can turn a two-dimensional periodic array of interconnected quantum rings into a topological insulator. The elaborated approach is applicable to calculate and analyze the electron energy spectrum of the array, the energy spectrum of the edge states, and the corresponding electronic densities. As a result, the present theory paves the way to optical control of the topological phases in ring-based mesoscopic structures.

  11. Time resolved spectroscopic studies on some nanophosphors

    Indian Academy of Sciences (India)

    Wintec

    . 1. Introduction. Time resolved spectroscopy is an important tool for study- ing energy and charge transfer processes, coupling of electronic and vibrational degrees of freedom, vibrational and conformational relaxation, isomerization, etc. The.

  12. Anisotropy-Guided Enantiomeric Enhancement in Alanine Using Far-UV Circularly Polarized Light.

    Science.gov (United States)

    Meinert, Cornelia; Cassam-Chenaï, Patrick; Jones, Nykola C; Nahon, Laurent; Hoffmann, Søren V; Meierhenrich, Uwe J

    2015-06-01

    All life on Earth is characterized by its asymmetry - both the genetic material and proteins are composed of homochiral monomers. Understanding how this molecular asymmetry initially arose is a key question related to the origins of life. Cometary ice simulations, L-enantiomeric enriched amino acids in meteorites and the detection of circularly polarized electromagnetic radiation in star-forming regions point to a possible interstellar/protostellar generation of stereochemical asymmetry. Based upon our recently recorded anisotropy spectra g(λ) of amino acids in the vacuum-UV range, we subjected amorphous films of racemic (13)C-alanine to far-UV circularly polarized synchrotron radiation to probe the asymmetric photon-molecule interaction under interstellar conditions. Optical purities of up to 4% were reached, which correlate with our theoretical predictions. Importantly, we show that chiral symmetry breaking using circularly polarized light is dependent on both the helicity and the wavelength of incident light. In order to predict such stereocontrol, time-dependent density functional theory was used to calculate anisotropy spectra. The calculated anisotropy spectra show good agreement with the experimental ones. The European Space Agency's Rosetta mission, which successfully landed Philae on comet 67P/Churyumov-Gerasimenko on 12 November 2014, will investigate the configuration of chiral compounds and thereby obtain data that are to be interpreted in the context of the results presented here.

  13. Time-resolved spectroscopy in synchrotron radiation

    International Nuclear Information System (INIS)

    Rehn, V.; Stanford Univ., CA

    1980-01-01

    Synchrotron radiation (SR) from large-diameter storage rings has intrinsic time structure which facilitates time-resolved measurements form milliseconds to picoseconds and possibly below. The scientific importance of time-resolved measurements is steadily increasing as more and better techniques are discovered and applied to a wider variety of scientific problems. This paper presents a discussion of the importance of various parameters of the SR facility in providing for time-resolved spectroscopy experiments, including the role of beam-line optical design parameters. Special emphasis is placed on the requirements of extremely fast time-resolved experiments with which the effects of atomic vibrational or relaxation motion may be studied. Before discussing the state-of-the-art timing experiments, we review several types of time-resolved measurements which have now become routine: nanosecond-range fluorescence decay times, time-resolved emission and excitation spectroscopies, and various time-of-flight applications. These techniques all depend on a short SR pulse length and a long interpulse period, such as is provided by a large-diameter ring operating in a single-bunch mode. In most cases, the pulse shape and even the stability of the pulse shape is relatively unimportant as long as the pulse length is smaller than the risetime of the detection apparatus, typically 1 to 2 ns. For time resolution smaller than 1 ns, the requirements on the pulse shape become more stringent. (orig./FKS)

  14. SEARCH FOR A MAGNETIC FIELD VIA CIRCULAR POLARIZATION IN THE WOLF-RAYET STAR EZ CMa

    International Nuclear Information System (INIS)

    De la Chevrotière, A.; St-Louis, N.; Moffat, A. F. J.

    2013-01-01

    We report on the first deep, direct search for a magnetic field via the circular polarization of Zeeman splitting in a Wolf-Rayet (W-R) star. Using the highly efficient ESPaDOnS spectropolarimeter at the Canada-France-Hawaii Telescope, we observed at three different epochs one of the best W-R candidates in the sky expected to harbor a magnetic field, the bright, highly variable WN4 star EZ CMa = WR6 = HD 50896. We looked for the characteristic circular polarization (Stokes V) pattern in strong emission lines that would arise as a consequence of a global, rotating magnetic field with a split monopole configuration. We also obtained nearly simultaneous linear polarization spectra (Stokes Q and U), which are dominated by electron scattering, most likely from a flattened wind with large-scale corotating structures. As the star rotates with a period of 3.766 days, our view of the wind changes, which in turn affects the value of the linear polarization in lines versus continuum at the ∼0.2% level. Depending on the epoch of observation, our Stokes V data were affected by significant crosstalk from Stokes Q and U to V. We removed this spurious signal from the circular polarization data and experimented with various levels of spectral binning to increase the signal-to-noise ratio of our data. In the end, no magnetic field is unambiguously detected in EZ CMa. Assuming that the star is intrinsically magnetic and harbors a split monopole configuration, we find an upper limit of B ∼ 100 G for the intensity of its field in the line-forming regions of the stellar wind.

  15. In-line production of a bi-circular field for generation of helically polarized high-order harmonics

    Energy Technology Data Exchange (ETDEWEB)

    Kfir, Ofer, E-mail: ofertx@technion.ac.il, E-mail: oren@si.technion.ac.il; Bordo, Eliyahu; Ilan Haham, Gil; Lahav, Oren; Cohen, Oren, E-mail: ofertx@technion.ac.il, E-mail: oren@si.technion.ac.il [Solid State Institute and Physics Department, Technion, Haifa 32000 (Israel); Fleischer, Avner [Solid State Institute and Physics Department, Technion, Haifa 32000 (Israel); Department of Physics and Optical Engineering, Ort Braude College, Karmiel 21982 (Israel)

    2016-05-23

    The recent demonstration of bright circularly polarized high-order harmonics of a bi-circular pump field gave rise to new opportunities in ultrafast chiral science. In previous works, the required nontrivial bi-circular pump field was produced using a relatively complicated and sensitive Mach-Zehnder-like interferometer. We propose a compact and stable in-line apparatus for converting a quasi-monochromatic linearly polarized ultrashort driving laser field into a bi-circular field and employ it for generation of helically polarized high-harmonics. Furthermore, utilizing the apparatus for a spectroscopic spin-mixing measurement, we identify the photon spins of the bi-circular weak component field that are annihilated during the high harmonics process.

  16. Generation of circularly polarized radiation from a compact plasma-based extreme ultraviolet light source for tabletop X-ray magnetic circular dichroism studies

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Daniel; Rudolf, Denis, E-mail: d.rudolf@fz-juelich.de; Juschkin, Larissa [RWTH Aachen University, Experimental Physics of EUV, Steinbachstraße 15, 52074 Aachen (Germany); Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany); Weier, Christian; Adam, Roman; Schneider, Claus M. [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-6), JARA-FIT, 52425 Jülich (Germany); Winkler, Gerrit; Frömter, Robert [Institut für Angewandte Physik, Universität Hamburg, Jungiusstraße 11, 20355 Hamburg (Germany); Danylyuk, Serhiy [RWTH Aachen University, Chair for Technology of Optical Systems, JARA-FIT, Steinbachstraße 15, 52074 Aachen (Germany); Bergmann, Klaus [Fraunhofer Institute for Laser Technology, Steinbachstrasse 15, 52074 Aachen (Germany); Grützmacher, Detlev [Forschungszentrum Jülich GmbH, Peter Grünberg Institut (PGI-9), JARA-FIT, 52425 Jülich (Germany)

    2014-10-15

    Generation of circularly polarized light in the extreme ultraviolet (EUV) spectral region (about 25 eV–250 eV) is highly desirable for applications in spectroscopy and microscopy but very challenging to achieve in a small-scale laboratory. We present a compact apparatus for generation of linearly and circularly polarized EUV radiation from a gas-discharge plasma light source between 50 eV and 70 eV photon energy. In this spectral range, the 3p absorption edges of Fe (54 eV), Co (60 eV), and Ni (67 eV) offer a high magnetic contrast often employed for magneto-optical and electron spectroscopy as well as for magnetic imaging. We simulated and designed an instrument for generation of linearly and circularly polarized EUV radiation and performed polarimetric measurements of the degree of linear and circular polarization. Furthermore, we demonstrate first measurements of the X-ray magnetic circular dichroism at the Co 3p absorption edge with a plasma-based EUV light source. Our approach opens the door for laboratory-based, element-selective spectroscopy of magnetic materials and spectro-microscopy of ferromagnetic domains.

  17. Circular motion of particles suspended in a Gaussian beam with circular polarization validates the spin part of the internal energy flow

    DEFF Research Database (Denmark)

    Angelsky, O. V.; Bekshaev, A. Ya.; Maksimyak, P. P.

    2012-01-01

    switching to the right (left) circular polarization, the particles performed spinning motion in agreement with the angular momentum imparted by the field, but they were involved in an orbital rotation around the beam axis as well, which in previous works [Y. Zhao et al, Phys. Rev. Lett. 99, 073901 (2007......Non-spherical dielectric microparticles were suspended in a water-filled cell and exposed to a coherent Gaussian light beam with controlled state of polarization. When the beam polarization is linear, the particles were trapped at certain off-axial position within the beam cross section. After...... of inhomogeneously polarized paraxial beams [A. Bekshaev et al, J. Opt. 13, 053001 (2011)]....

  18. Optimized fan-shaped chiral metamaterial as an ultrathin narrow-band circular polarizer at visible frequencies

    Science.gov (United States)

    He, Yizhuo; Wang, Xinghai; Ingram, Whitney; Ai, Bin; Zhao, Yiping

    2018-04-01

    Chiral metamaterials have the great ability to manipulate the circular polarizations of light, which can be utilized to build ultrathin circular polarizers. Here we build a narrow-band circular polarizer at visible frequencies based on plasmonic fan-shaped chiral nanostructures. In order to achieve the best optical performance, we systematically investigate how different fabrication factors affect the chiral optical response of the fan-shaped chiral nanostructures, including incident angle of vapor depositions, nanostructure thickness, and post-deposition annealing. The optimized fan-shaped nanostructures show two narrow bands for different circular polarizations with the maximum extinction ratios 7.5 and 6.9 located at wavelength 687 nm and 774 nm, respectively.

  19. Circularly Polarized X Rays: Another Probe of Ultrafast Molecular Decay Dynamics

    International Nuclear Information System (INIS)

    Travnikova, Oksana; Lindblad, Andreas; Nicolas, Christophe; Soederstroem, Johan; Kimberg, Victor; Miron, Catalin; Liu Jicai; Gel'mukhanov, Faris

    2010-01-01

    Dissociative nuclear motion in core-excited molecular states leads to a splitting of the fragment Auger lines: the Auger-Doppler effect. We present here for the first time experimental evidence for an Auger-Doppler effect following F1s→a 1g * inner-shell excitation by circularly polarized x rays in SF 6 . In spite of a uniform distribution of the dissociating S-F bonds near the polarization plane of the light, the intersection between the subpopulation of molecules selected by the core excitation with the cone of dissociation induces a strong anisotropy in the distribution of the S-F bonds that contributes to the scattering profile measured in the polarization plane.

  20. Nonlinear Free Vibration Analysis of Axisymmetric Polar Orthotropic Circular Membranes under the Fixed Boundary Condition

    Directory of Open Access Journals (Sweden)

    Zhoulian Zheng

    2014-01-01

    Full Text Available This paper presents the nonlinear free vibration analysis of axisymmetric polar orthotropic circular membrane, based on the large deflection theory of membrane and the principle of virtual displacement. We have derived the governing equations of nonlinear free vibration of circular membrane and solved them by the Galerkin method and the Bessel function to obtain the generally exact formula of nonlinear vibration frequency of circular membrane with outer edges fixed. The formula could be degraded into the solution from small deflection vibration; thus, its correctness has been verified. Finally, the paper gives the computational examples and comparative analysis with the other solution. The frequency is enlarged with the increase of the initial displacement, and the larger the initial displacement is, the larger the effect on the frequency is, and vice versa. When the initial displacement approaches zero, the result is consistent with that obtained on the basis of the small deflection theory. Results obtained from this paper provide the accurate theory for the measurement of the pretension of polar orthotropic composite materials by frequency method and some theoretical basis for the research of the dynamic response of membrane structure.

  1. Time-resolved absorption measurements on OMEGA

    International Nuclear Information System (INIS)

    Jaanimagi, P.A.; DaSilva, L.; Delettrez, J.; Gregory, G.G.; Richardson, M.C.

    1986-01-01

    Time-resolved measurements of the incident laser light that is scattered and/or refracted from targets irradiated by the 24 uv-beam OMEGA laser at LLE, have provided some interesting features related to time-resolved absorption. The decrease in laser absorption characteristic of irradiating a target that implodes during the laser pulse has been observed. The increase in absorption expected as the critical density surface moves from a low to a high Z material in the target has also been noted. The detailed interpretation of these results is made through comparisons with simulation using the code LILAC, as well as with streak data from time-resolved x-ray imaging and spectroscopy. In addition, time and space-resolved imaging of the scattered light yields information on laser irradiation uniformity conditions on the target. The report consists of viewgraphs

  2. Circular polarization of gravitational waves from non-rotating supernova cores: a new probe into the pre-explosion hydrodynamics

    Science.gov (United States)

    Hayama, Kazuhiro; Kuroda, Takami; Kotake, Kei; Takiwaki, Tomoya

    2018-04-01

    We present an analysis of the circular polarization of gravitational-waves (GWs) using results from three-dimensional (3D), general relativistic (GR) core-collapse simulations of a non-rotating 15M⊙ star. For the signal detection, we perform a coherent network analysis taking into account the four interferometers of LIGO Hanford, LIGO Livingston, VIRGO, and KAGRA. We focus on the Stokes V parameter, which directly characterizes the asymmetry of the GW circular polarization. We find that the amplitude of the GW polarization becomes bigger for our 3D-GR model that exhibits strong activity of the standing accretion shock instability (SASI). Our results suggest that the SASI-induced accretion flows to the proto-neutron star (PNS) lead to a characteristic, low-frequency modulation (100 ˜ 200 Hz) in both the waveform and the GW circular polarization. By estimating the signal-to-noise ratio of the GW polarization, we demonstrate that the detection horizon of the circular polarization extends by more than a factor of several times farther comparing to that of the GW amplitude. Our results suggest that the GW circular polarization, if detected, could provide a new probe into the pre-explosion hydrodynamics such as the SASI activity and the g-mode oscillation of the PNS.

  3. Strong Circularly Polarized Luminescence from Highly Emissive Terbium Complexes in Aqueous Solution

    Energy Technology Data Exchange (ETDEWEB)

    Samuel, Amanda; Lunkley, Jamie; Muller, Gilles; Raymond, Kenneth

    2010-03-15

    Two luminescent terbium(III) complexes have been prepared from chiral ligands containing 2-hydroxyisophthalamide (IAM) antenna chromophores and their non-polarized and circularly-polarized luminescence properties have been studied. These tetradentate ligands, which form 2:1 ligand/Tb{sup III} complexes, utilize diaminocyclohexane (cyLI) and diphenylethylenediamine (dpenLI) backbones, which we reasoned would impart conformational rigidity and result in Tb{sup III} complexes that display both large luminescence quantum yield ({phi}) values and strong circularly polarized luminescence (CPL) activities. Both Tb{sup III} complexes are highly emissive, with {phi} values of 0.32 (dpenLI-Tb) and 0.60 (cyLI-Tb). Luminescence lifetime measurements in H{sub 2}O and D{sub 2}O indicate that while cyLI-Tb exists as a single species in solution, dpenLI-Tb exists as two species: a monohydrate complex with one H{sub 2}O molecule directly bound to the Tb{sup III} ion and a complex with no water molecules in the inner coordination sphere. Both cyLI-Tb and dpenLI-Tb display increased CPL activity compared to previously reported Tb{sup III} complexes made with chiral IAM ligands. The CPL measurements also provide additional confirmation of the presence of a single emissive species in solution in the case of cyLI-Tb, and multiple emissive species in the case of dpenLI-Tb.

  4. Uncovering the Circular Polarization Potential of Chiral Photonic Cellulose Films for Photonic Applications.

    Science.gov (United States)

    Zheng, Hongzhi; Li, Wanru; Li, Wen; Wang, Xiaojun; Tang, Zhiyong; Zhang, Sean Xiao-An; Xu, Yan

    2018-02-12

    Circularly polarized light (CPL) is central to photonic technologies. A key challenge lies in developing a general route for generation of CPL with tailored chiroptical activity using low-cost raw materials suitable for scale-up. This study presents that cellulose films with photonic bandgaps (PBG) and left-handed helical sense have an intrinsic ability for circular polarization leading to PBG-based CPL with extraordinary |g | values, well-defiend handedness, and tailorable wavelength by the PBG change. Using such cellulose films, incident light ranging from near-UV to near-IR can be transformed to passive L-CPL and R-CPL with viewing-side-dependent handedness and |g | values up to 0.87, and spontaneous emission transformed to R-CPL emission with |g | values up to 0.68. Unprecedented evidence is presented with theoretical underpinning that the PBG effect can stimulate the R-CPL emission. The potential of cellulose-based CPL films for polarization-based encryption is illustrated. The evaporation-induced self-assembly coupled with nanoscale mesogens of cellulose nanocrystals opens new venues for technological advances and enables a versatile strategy for rational design and scalable manufacturing of organic and inorganic CPL films for photonic applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Multiport Circular Polarized RFID-Tag Antenna for UHF Sensor Applications.

    Science.gov (United States)

    Zaid, Jamal; Abdulhadi, Abdulhadi; Kesavan, Arun; Belaizi, Yassin; Denidni, Tayeb A

    2017-07-05

    A circular polarized patch antenna for UHF RFID tag-based sensor applications is presented, with the circular polarization (CP) generated by a new antenna shape, an asymmetric stars shaped slotted microstrip patch antenna (CP-ASSSMP). Four stars etched on the patch allow the antenna's size to be reduced by close to 20%. The proposed antenna is matched with two RFID chips via inductive-loop matching. The first chip is connected to a resistive sensor and acts as a sensor node, and the second is used as a reference node. The proposed antenna is used for two targets, serving as both reference and sensor simultaneously, thereby eliminating the need for a second antenna. Its reader can read the RFID chips at any orientation of the tag due to the CP. The measured reading range is about 25 m with mismatch polarization. The operating frequency band is 902-929 MHz for the two ports, which is covered by the US RFID band, and the axial-ratio bandwidth is about 7 MHz. In addition, the reader can also detect temperature, based on the minimum difference in the power required by the reference and sensor.

  6. Miniature magnetic bottle confined by circularly polarized laser light and measurements of the inverse Faraday effect in plasmas

    International Nuclear Information System (INIS)

    Eliezer, S.; Paiss, Y.; Horovitz, Y.; Henis, Z.

    1997-01-01

    A new concept of hot plasma confinement in a miniature magnetic bottle induced by circularly polarized laser light is suggested. Magnetic fields generated by circularly polarized laser light may be of the order of megagauss, depending on the laser intensity. In this configuration the circularly polarized light is used to obtain confinement of a plasma contained in a good conductor vessel. The confinement in this scheme is supported by the magnetic forces. The Lawson criterion for a DT plasma might be achieved for number density n = 5*10 21 cm -3 and confinement time τ= 20 ns. The laser and plasma parameters required to obtain an energetic gain are calculated. Experiments and preliminary calculations were performed to study the feasibility of the above scheme. Measurements of the axial magnetic field induced by circularly polarized laser light, the so called inverse Faraday effect, and of the absorption of circularly polarized laser light in plasma, are reported. The experiments were performed with a circularly polarized Nd:YAG laser, having a wavelength of 1.06 τm and a pulse duration of 7 ns, in a range of irradiances from 10 9 to 10 14 W/cm 2 . Axial magnetic fields from 500 Gauss to 2 megagauss were measured. Up to 5*10 13 W/cm 3 the results are in agreement with a nonlinear model of the inverse Faraday effect dominated by the ponderomotive force. For the laser irradiance studied here, 9*10 13 - 2.5*10 14 W/cm 2 , the absorption of circularly polarized light was 14% higher relative to the absorption of linear polarized light

  7. Circularly polarized few-optical-cycle solitons in the short-wave-approximation regime

    Energy Technology Data Exchange (ETDEWEB)

    Leblond, Herve [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Triki, Houria [Radiation Physics Laboratory, Department of Physics, Faculty of Sciences, Badji Mokhtar University, Post Office Box 12, 23000 Annaba (Algeria); Mihalache, Dumitru [Laboratoire de Photonique d' Angers, EA 4464, Universite d' Angers, 2 Boulevard Lavoisier, F-49045 Angers Cedex 01 (France); Horia Hulubei National Institute for Physics and Nuclear Engineering (IFIN-HH), 407 Atomistilor, RO-077125 Magurele-Bucharest (Romania); Academy of Romanian Scientists, 54 Splaiul Independentei, RO-050094 Bucharest (Romania)

    2011-08-15

    We consider the propagation of few-cycle pulses (FCPs) beyond the slowly varying envelope approximation in media in which the dynamics of constituent atoms is described by a two-level Hamiltonian by taking into account the wave polarization. We consider the short-wave approximation, assuming that the resonance frequency of the two-level atoms is well below the inverse of the characteristic duration of the optical pulse. By using the reductive perturbation method (multiscale analysis), we derive from the Maxwell-Bloch-Heisenberg equations the governing evolution equations for the two polarization components of the electric field in the first order of the perturbation approach. We show that propagation of circularly polarized (CP) few-optical-cycle solitons is described by a system of coupled nonlinear equations, which reduces in the scalar case to the standard sine Gordon equation describing the dynamics of linearly polarized FCPs in the short-wave-approximation regime. By direct numerical simulations, we calculate the lifetime of CP FCPs, and we study the transition to two orthogonally polarized single-humped pulses as a generic route of their instability.

  8. Decomposition of time-resolved tomographic PIV

    NARCIS (Netherlands)

    Schmid, P.J.; Violato, D.; Scarano, F.

    2012-01-01

    An experimental study has been conducted on a transitional water jet at a Reynolds number of Re = 5,000. Flow fields have been obtained by means of time-resolved tomographic particle image velocimetry capturing all relevant spatial and temporal scales. The measured threedimensional flow fields have

  9. Raman backscattering of circularly polarized electromagnetic waves propagating along a magnetic field

    International Nuclear Information System (INIS)

    Maraghechi, B.; Willett, J.e.

    1979-01-01

    The stimulated Raman backscattering of an intense electromagnetic wave propagating in the extraordinary mode along a uniform, static magnetic field is considered. The dispersion relation for a homogeneous magnetized plasma in the presence of the circularly polarized pump waves is developed in the cold-plasma approximation with the pump frequency above the plasma frequency. Formulas are derived for the threshold νsub(OT) of the parametric instability and for the growth rate γ of the backscattered extraordinary wave and Langmuir wave. The effects of the magnetic field parallel to the direction of propagation on νsub(0T) and γ are studied numerically. (author)

  10. Unpinning of rotating spiral waves in cardiac tissues by circularly polarized electric fields

    Science.gov (United States)

    Feng, Xia; Gao, Xiang; Pan, De-Bei; Li, Bing-Wei; Zhang, Hong

    2014-04-01

    Spiral waves anchored to obstacles in cardiac tissues may cause lethal arrhythmia. To unpin these anchored spirals, comparing to high-voltage side-effect traditional therapies, wave emission from heterogeneities (WEH) induced by the uniform electric field (UEF) has provided a low-voltage alternative. Here we provide a new approach using WEH induced by the circularly polarized electric field (CPEF), which has higher success rate and larger application scope than UEF, even with a lower voltage. And we also study the distribution of the membrane potential near an obstacle induced by CPEF to analyze its mechanism of unpinning. We hope this promising approach may provide a better alternative to terminate arrhythmia.

  11. Investigation of beam self-polarization in the future e+e− circular collider

    CERN Document Server

    AUTHOR|(CDS)2075800

    2016-10-24

    The use of resonant depolarization has been suggested for precise beam energy measurements (better than 100 keV) in the eþe− Future Circular Collider (FCC-eþe−) for Z and WW physics at 45 and 80 GeV beam energy respectively. Longitudinal beam polarization would benefit the Z peak physics program; however it is not essential and therefore it will be not investigated here. In this paper the possibility of selfpolarized leptons is considered. Preliminary results of simulations in presence of quadrupole misalignments and beam position monitors (BPMs) errors for a simplified FCC-eþe− ring are presented.

  12. Photoionization in the presence of circularly polarized fundamental and odd-order harmonic fields

    Science.gov (United States)

    Ivanov, I. A.; Nam, Chang Hee; Kim, Kyung Taec

    2017-05-01

    We present a study of the photoelectron spectra for the ionization process driven by counterrotating and corotating circularly polarized fundamental and odd-order harmonic fields. The main features of the spectra, such as symmetric lobed structures, are understood using simple arguments based on the strong field approximation (SFA) picture of ionization. A deviation from this picture is, most notably, the presence of the low-energy structures (LES) in the spectra. We show that the Rydberg states populated as a result of the combined absorption of the photons from the fundamental and harmonic fields are responsible for the origin of LES.

  13. Dynamical polarizability of graphene irradiated by circularly polarized ac electric fields

    DEFF Research Database (Denmark)

    Busl, Maria; Platero, Gloria; Jauho, Antti-Pekka

    2012-01-01

    We examine the low-energy physics of graphene in the presence of a circularly polarized electric field in the terahertz regime. Specifically, we derive a general expression for the dynamical polarizability of graphene irradiated by an ac electric field. Several approximations are developed...... that allow one to develop a semianalytical theory for the weak-field regime. The ac field changes qualitatively the single- and many-electron excitations of graphene: Undoped samples may exhibit collective excitations (in contrast to the equilibrium situation), and the properties of the excitations in doped...

  14. Analytical Solutions of Temporal Evolution of Populations in Optically-Pumped Atoms with Circularly Polarized Light

    Directory of Open Access Journals (Sweden)

    Heung-Ryoul Noh

    2016-03-01

    Full Text Available We present an analytical calculation of temporal evolution of populations for optically pumped atoms under the influence of weak, circularly polarized light. The differential equations for the populations of magnetic sublevels in the excited state, derived from rate equations, are expressed in the form of inhomogeneous second-order differential equations with constant coefficients. We present a general method of analytically solving these differential equations, and obtain explicit analytical forms of the populations of the ground state at the lowest order in the saturation parameter. The obtained populations can be used to calculate lineshapes in various laser spectroscopies, considering transit time relaxation.

  15. Scattering of inhomogeneous circularly polarized optical field and mechanical manifestation of the internal energy flows

    DEFF Research Database (Denmark)

    Bekshaev, A. Ya; Angelsky, O. V.; Hanson, Steen Grüner

    2012-01-01

    Based on the Mie theory and on the incident beam model via superposition of two plane waves, we analyze numerically the momentum flux of the field scattered by a spherical, nonmagnetic microparticle placed within the spatially inhomogeneous circularly polarized paraxial light beam. The asymmetry...... between the forward- and backward-scattered momentum fluxes in the Rayleigh scattering regime appears due to the spin part of the internal energy flow in the incident beam. The transverse ponderomotive forces exerted on dielectric and conducting particles of different sizes are calculated and special...

  16. Frequency-driven quantum oscillations in a graphene layer under circularly polarized ac fields

    Energy Technology Data Exchange (ETDEWEB)

    Vega Monroy, R., E-mail: ricardovega@mail.uniatlantico.edu.co; Martinez Castro, O.; Salazar Cohen, G.

    2015-06-19

    In this paper we predict a new type of quantum oscillations driven by the frequency of a circularly polarized ac field in a monolayer of graphene placed inside an optical cavity. We show that the displacement of the structure of photon-dressed electron states near the Fermi level and the electron transitions, from extended states to bound photon-dressed electron states inside an energy gap, lead to a periodic change of singularities in the electron density of states, resulting in quantum oscillations in thermodynamic, transport and other properties in graphene.

  17. Graphene superlattices in strong circularly polarized fields: Chirality, Berry phase, and attosecond dynamics

    Science.gov (United States)

    Koochaki Kelardeh, Hamed; Apalkov, Vadym; Stockman, Mark I.

    2017-08-01

    We propose and theoretically explore states of graphene superlattices with relaxed P and T symmetries created by strong circularly polarized ultrashort pulses. The conduction-band electron distribution in the reciprocal space forms an interferogram with discontinuities related to topological (Berry) fluxes at the Dirac points. This can be studied using time- and angle-resolved photoemission spectroscopy (TR-ARPES). Our findings hold promise for control and observation of ultrafast electron dynamics in topological solids and may be applied to petahertz-scale information processing.

  18. Circularly polarized lasing in chiral modulated semiconductor microcavity with GaAs quantum wells

    OpenAIRE

    Demenev, A. A.; Kulakovskii, V. D.; Schneider, C.; Brodbeck, S.; Kamp, M.; Höfling, S.; Lobanov, S. V.; Weiss, T.; Gippius, N. A.; Tikhodeev, S. G.

    2016-01-01

    This work has been funded by Russian Scientific Foundation (Grant No. 14-12-01372) and State of Bavaria. We report close to circularly polarized lasing at ћω = 1.473 and 1.522 eV from an AlAs/AlGaAs Bragg microcavity, with 12 GaAs quantum wells in the active region and chirally etched upper distributed Bragg refractor under optical pump at room temperature. The advantage of using the chiral photonic crystal with a large contrast of dielectric permittivities is its giant optical activity, a...

  19. Dynamical behaviour of FEL devices operating with two undulators having opposite circular polarizations

    International Nuclear Information System (INIS)

    Dattoli, G.; Ottaviani, P. L.; Bucci, L.

    2000-01-01

    Optical-Klystron FELs operating with undulators having opposite circular polarizations are characterized by a spontaneous emission spectrum which does not exhibit the characteristic interference pattern. The use of the Madey theorem may allow the conclusion that, for such configuration, the dispersive section does not provide any gain enhancement. In this paper it has been analyzed the problem from a dynamical point of view and clarify how the optical field evolve, what is the role of the bunching and how the consequences of the Madey theorem should be correctly understood [it

  20. Vitamin E Circular Dichroism Studies: Insights into Conformational Changes Induced by the Solvent’s Polarity

    Directory of Open Access Journals (Sweden)

    Drew Marquardt

    2016-12-01

    Full Text Available We used circular dichroism (CD to study differences in CD spectra between α-, δ-, and methylated-α-tocopherol in solvents with different polarities. CD spectra of the different tocopherol structures differ from each other in intensity and peak locations, which can be attributed to chromanol substitution and the ability to form hydrogen bonds. In addition, each structure was examined in different polarity solvents using the Reichardt index—a measure of the solvent’s ionizing ability, and a direct measurement of solvent–solute interactions. Differences across solvents indicate that hydrogen bonding is a key contributor to CD spectra at 200 nm. These results are a first step in examining the hydrogen bonding abilities of vitamin E in a lipid bilayer.

  1. Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

    DEFF Research Database (Denmark)

    Dimitrovski, Darko; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2011-01-01

    We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction...... of the molecular electric dipole moment. These findings are explained by a tunneling model invoking the laser-induced Stark shifts associated with the dipoles and polarizabilities of the molecule and its unrelaxed cation. The focus of the present article is to understand the strong-field ionization of one......-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron...

  2. Self-organized pattern formation upon femtosecond laser ablation by circularly polarized light

    International Nuclear Information System (INIS)

    Varlamova, Olga; Costache, Florenta; Reif, Juergen; Bestehorn, Michael

    2006-01-01

    Surface ripples generation upon femtosecond laser ablation is attributed to self-organized structure formation from instability. We report that linear arrangements are observed not only for linearly polarized light but also for ablation with circularly polarized light. Long ordered chains of spherical nanoparticles, reminding of bead-strings are almost parallel but exhibit typical non-linear dynamics features such as bifurcations. In a first attempt to understand the self-assembly, we rely on models recently developed for the description of similar structures upon ion beam erosion and for the simulation of instabilities in thin liquid films. Our picture describes an unstable surface layer, non-uniformly eroded through Coulomb repulsion between individual positive charges

  3. Circularly polarized reflection from the scarab beetle Chalcothea smaragdina: light scattering by a dual photonic structure.

    Science.gov (United States)

    McDonald, Luke T; Finlayson, Ewan D; Wilts, Bodo D; Vukusic, Pete

    2017-08-06

    Helicoidal architectures comprising various polysaccharides, such as chitin and cellulose, have been reported in biological systems. In some cases, these architectures exhibit stunning optical properties analogous to ordered cholesteric liquid crystal phases. In this work, we characterize the circularly polarized reflectance and optical scattering from the cuticle of the beetle Chalcothea smaragdina (Coleoptera: Scarabaeidae: Cetoniinae) using optical experiments, simulations and structural analysis. The selective reflection of left-handed circularly polarized light is attributed to a Bouligand-type helicoidal morphology within the beetle's exocuticle. Using electron microscopy to inform electromagnetic simulations of this anisotropic stratified medium, the inextricable connection between the colour appearance of C. smaragdina and the periodicity of its helicoidal rotation is shown. A close agreement between the model and the measured reflectance spectra is obtained. In addition, the elytral surface of C. smaragdina possesses a blazed diffraction grating-like surface structure, which affects the diffuse appearance of the beetle's reflected colour, and therefore potentially enhances crypsis among the dense foliage of its rainforest habitat.

  4. Circularly Polarized S Band Dual Frequency Square Patch Antenna Using Glass Microfiber Reinforced PTFE Composite

    Directory of Open Access Journals (Sweden)

    M. Samsuzzaman

    2014-01-01

    Full Text Available Circularly polarized (CP dual frequency cross-shaped slotted patch antenna on 1.575 mm thick glass microfiber reinforced polytetrafluoroethylene (PTFE composite material substrate is designed and fabricated for satellite applications. Asymmetric cross-shaped slots are embedded in the middle of the square patch for CP radiation and four hexagonal slots are etched on the four sides of the square patch for desired dual frequency. Different substrate materials have been analysed to achieve the desired operating band. The experimental results show that the impedance bandwidth is approximately 30 MHz (2.16 GHz to 2.19 GHz for lower band and 40 MHz (3.29 GHz to 3.33 GHz for higher band with an average peak gain of 6.59 dBiC and 5.52 dBiC, respectively. Several optimizations are performed to obtain the values of the antenna physical parameters. Moreover, the proposed antenna possesses compactness, light weight, simplicity, low cost, and circularly polarized. It is an attractive candidate for dual band satellite antennas where lower band can be used for uplink and upper band can be used for downlink.

  5. Circularly Polarized Luminescence from a Pyrene-Cyclodextrin Supra-Dendron.

    Science.gov (United States)

    Zhang, Yuening; Yang, Dong; Han, Jianlei; Zhou, Jin; Jin, Qingxian; Liu, Minghua; Duan, Pengfei

    2018-04-19

    Soft nanomaterials with circularly polarized luminescence (CPL) have been currently attracting great interests. Here, we report a pyrene-containing π-peptide dendrons hydrogel, which showed 1D and 2D nanostructures with varied CPL activities. It was found that the individual dendron formed hydrogels in a wide pH range (3-12) and self-assembled into helices with pH-tuned pitches. Through chirality transfer, the pyrene unit could show CPL originated from both the monomer and excimer bands. When cyclodextrin was introduced, different supra-dendrons were obtained with β-cyclodextrin (PGAc@β-CD) and γ-cyclodextrin (PGAc@γ-CD) through host-guest interactions, respectively. Interestingly, the PGAc@β-CD and PGAc@γ-CD supra-dendrons self-assembled into 2D nanosheet and entangled nanofibers, respectively, showing cyclodextrin induced circularly polarized emission from both the monomer and excimer bands of pyrene moiety. Thus, through a simple host-guest interaction, both the nanostructures and the chiroptical activities could be modulated.

  6. Vitrified chiral-nematic liquid crystalline films for selective reflection and circular polarization

    Energy Technology Data Exchange (ETDEWEB)

    Katsis, D.; Chen, P.H.M.; Mastrangelo, J.C.; Chen, S.H. [Univ. of Rochester, NY (United States); Blanton, T.N. [Eastman Kodak Co., Rochester, NY (United States)

    1999-06-01

    Nematic and left-handed chiral-nematic liquid crystals comprising methoxybiphenylbenzoate and (S)-(-)-1-phenylethylamine pendants to a cyclohexane core were synthesized and characterized. Although pristine samples were found to be polycrystalline, thermal quenching following heating to and annealing at elevated temperatures permitted the molecular orders characteristic of liquid crystalline mesomorphism to be frozen in the glassy state. Left at room temperature for 6 months, the vitrified liquid crystalline films showed no evidence of recrystallization. An orientational order parameter of 0.65 was determined with linear dichroism of a vitrified nematic film doped with Exalite 428 at a mole fraction of 0.0025. Birefringence dispersion of a blank vitrified nematic film was determined using a phase-difference method complemented by Abbe refractometry. A series of vitrified chiral-nematic films were prepared to demonstrate selective reflection and circular polarization with a spectral region tunable from blue to the infrared region by varying the chemical composition. The experimentally measured circular polarization spectra were found to agree with the Good-Karali theory in which all four system parameters were determined a priori: optical birefringence, average refractive index, selective reflection wavelength, and film thickness.

  7. Hole dynamics and spin currents after ionization in strong circularly polarized laser fields

    International Nuclear Information System (INIS)

    Barth, Ingo; Smirnova, Olga

    2014-01-01

    We apply the time-dependent analytical R-matrix theory to develop a movie of hole motion in a Kr atom upon ionization by strong circularly polarized field. We find rich hole dynamics, ranging from rotation to swinging motion. The motion of the hole depends on the final energy and the spin of the photoelectron and can be controlled by the laser frequency and intensity. Crucially, hole rotation is a purely non-adiabatic effect, completely missing in the framework of quasistatic (adiabatic) tunneling theories. We explore the possibility to use hole rotation as a clock for measuring ionization time. Analyzing the relationship between the relative phases in different ionization channels we show that in the case of short-range electron-core interaction the hole is always initially aligned along the instantaneous direction of the laser field, signifying zero delays in ionization. Finally, we show that strong-field ionization in circular fields creates spin currents (i.e. different flow of spin-up and spin-down density in space) in the ions. This phenomenon is intimately related to the production of spin-polarized electrons in strong laser fields Barth and Smirnova (2013 Phys. Rev. A 88 013401). We demonstrate that rich spin dynamics of electrons and holes produced during strong field ionization can occur in typical experimental conditions and does not require relativistic intensities or strong magnetic fields. (paper)

  8. Optically ambidextrous circularly polarized reflection from the chiral cuticle of the scarab beetle Chrysina resplendens.

    Science.gov (United States)

    Finlayson, Ewan D; McDonald, Luke T; Vukusic, Pete

    2017-06-01

    The evolution of structural colour mechanisms in biological systems has given rise to many interesting optical effects in animals and plants. The instance of the scarab beetle Chrysina resplendens is particularly distinctive. Its exoskeleton has a bright, golden appearance and reflects both right-handed and left-handed circularly polarized light concurrently. The chiral nanostructure responsible for these properties is a helicoid, in which birefringent dielectric planes are assembled with an incremental rotation. This study correlates details of the beetle's circularly polarized reflectance spectra directly with physical aspects of its structural morphology. Electron micrography is used to identify and measure the physical dimensions of the key constituent components. These include a chiral multilayer configuration comprising two chirped, left-handed helicoids that are separated by a birefringent retarder. A scattering matrix technique is used to simulate the system's optical behaviour in which the roles of each component of the morphological substructure are elucidated by calculation of the fields throughout its depth. © 2017 The Author(s).

  9. A solid-state dedicated circularly polarized luminescence spectrophotometer: Development and application.

    Science.gov (United States)

    Harada, Takunori; Hayakawa, Hiroshi; Watanabe, Masayuki; Takamoto, Makoto

    2016-07-01

    A new solid-state dedicated circularly polarized luminescence (CPL) instrument (CPL-200CD) was successfully developed for measuring true CPL spectra for optically anisotropic samples on the basis of the Stokes-Mueller matrix approach. Electric components newly installed in the CPL-200CD include a pulse motor-driven sample rotation holder and a 100 kHz lock-in amplifier to achieve the linearly polarized luminescence measurement, which is essential for obtaining the true CPL signal for optically anisotropic samples. An acquisition approach devised for solid-state CPL analysis reduces the measurement times for a data set by ca. 98% compared with the time required in our previous method. As a result, the developed approach is very effective for samples susceptible to light-induced degradation. The theory and implementation of the method are described, and examples of its application to a CPL sample with macroscopic anisotropies are provided. An important advantage of the developed instrument is its ability to obtain molecular information for both excited and ground states because circular dichroism measurements can be performed by switching the monochromatic light to white light without rearrangement of the sample.

  10. Circularly Polarized Low-Profile Antenna for Radiating Parallel to Ground Plane for RFID Reader Applications

    Directory of Open Access Journals (Sweden)

    Kittima Lertsakwimarn

    2013-01-01

    Full Text Available This paper presents a low-profile printed antenna with double U-shaped arms radiating circular polarization for the UHF RFID readers. The proposed antenna consists of double U-shaped strip structures and a capacitive feeding line to generate circular polarization. A part of the U-shaped arms is bent by 90° to direct the main beam parallel to the ground plane. From the results, -10 dB |S11| and 3 dB axial ratio of the antenna cover a typical UHF RFID band from 920 MHz to 925 MHz. The bidirectional beam is obtained with the maximum gain of 1.8 dBic in the parallel direction to the ground plane at the 925 MHz. The overall size of the proposed antenna including ground plane is 107 mm × 57 mm × 12.8 mm (0.33λ0 × 0.17λ0 × 0.04λ0.

  11. Improvement of RF Wireless Power Transmission Using a Circularly Polarized Retrodirective Antenna Array with EBG Structures

    Directory of Open Access Journals (Sweden)

    Son Trinh-Van

    2018-02-01

    Full Text Available This paper presents the performance improvement of a circularly polarized (CP retrodirective array (RDA through the suppression of mutual coupling effects. The RDA is designed based on CP Koch-shaped patch antenna elements with an inter-element spacing as small as 0.4 λ for a compact size ( λ is the wavelength in free space at the designed frequency of 5.2 GHz. Electromagnetic band gap (EBG structures are applied to reduce the mutual coupling between the antenna elements, thus improving the circular polarization characteristic of the RDA. Two CP RDAs with EBGs, in the case 5 × 5 and 10 × 10 arrays, are used as wireless power transmitters to transmit a total power of 50 W. A receiver is located at a distance of 1 m away from the transmitter to harvest the transmitted power. At the broadside direction, the simulated results demonstrate that the received powers are improved by approximately 11.32% and 12.45% when using the 5 × 5 and 10 × 10 CP RDAs with the EBGs, respectively, as the transmitters.

  12. 77 GHz MEMS antennas on high-resistivity silicon for linear and circular polarization

    KAUST Repository

    Sallam, M. O.

    2011-07-01

    Two new MEMS antennas operating at 77 GHz are presented in this paper. The first antenna is linearly polarized. It possesses a vertical silicon wall that carries a dipole on top of it. The wall is located on top of silicon substrate covered with a ground plane. The other side of the substrate carries a microstrip feeding network in the form of U-turn that causes 180 phase shift. This phase-shifter feeds the arms of the dipole antenna via two vertical Through-Silicon Vias (TSVs) that go through the entire wafer. The second antenna is circularly polarized and formed using two linearly polarized antennas spatially rotated with respect to each other by 90 and excited with 90 phase shift. Both antennas are fabricated using novel process flow on a single high-resistivity silicon wafer via bulk micromachining. Only three processing steps are required to fabricate these antennas. The proposed antennas have appealing characteristics, such as high polarization purity, high gain, and high radiation efficiency. © 2011 IEEE.

  13. Beamline 9.3.2 - a high-resolution, bend-magnet beamline with circular polarization capability

    Energy Technology Data Exchange (ETDEWEB)

    Moler, E.J.; Hussain, Z.; Howells, M.R. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Beamline 9.3.2 is a high resolution, SGM beamline on an ALS bending magnet with access to photon energies from 30-1500 eV. Features include circular polarization capability, a rotating chamber platform that allows switching between experiments without breaking vacuum, an active feedback system that keeps the beam centered on the entrance slit of the monochromator, and a bendable refocusing mirror. The beamline optics consist of horizontally and vertically focussing mirrors, a Spherical Grating Monochromator (SGM) with movable entrance and exit slits, and a bendable refocussing mirror. In addition, a movable aperature has been installed just upstream of the vertically focussing mirror which can select the x-rays above or below the plane of the synchrotron storage ring, allowing the user to select circularly or linearly polarized light. Circularly polarized x-rays are used to study the magnetic properties of materials. Beamline 9.3.2 can supply left and right circularly polarized x-rays by a computer controlled aperture which may be placed above or below the plane of the synchrotron storage ring. The degree of linear and circular polarization has been measured and calibrated.

  14. Deflection evaluation using time-resolved radiography

    International Nuclear Information System (INIS)

    Fry, D.A.; Lucero, J.P.

    1990-01-01

    Time-resolved radiography is the creation of an x-ray image for which both the start-exposure and stop-exposure times are known with respect to the event under study. The combination of image and timing are used to derive information about the event. The authors have applied time-resolved radiography to evaluate motions of explosive-driven events. In the particular application discussed in this paper, the author's intent is to measure maximum deflections of the components involved. Exposures are made during the time just before to just after the event of interest occurs. A smear or blur of motion out to its furthest extent is recorded on the image. Comparison of the dynamic images with static images allows deflection measurements to be made

  15. Generation of circularly polarized XUV and soft-x-ray high-order harmonics by homonuclear and heteronuclear diatomic molecules subject to bichromatic counter-rotating circularly polarized intense laser fields

    Science.gov (United States)

    Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

    2017-12-01

    Recently, studies of bright circularly polarized high-harmonic beams from atoms in the soft-x-ray region as a source for x-ray magnetic circular dichroism measurement in a tabletop-scale setup have received considerable attention. In this paper, we address the problem with molecular targets and perform a detailed quantum study of H2 +, CO, and N2 molecules in bichromatic counter-rotating circularly polarized laser fields where we adopt wavelengths (1300 and 790 nm) and intensities (2 ×1014W /cm2 ) reported in a recent experiment [Proc. Natl. Acad. Sci. USA 112, 14206 (2015), 10.1073/pnas.1519666112]. Our treatment of multiphoton processes in homonuclear and heteronuclear diatomic molecules is nonperturbative and based on the time-dependent density-functional theory for multielectron systems. The calculated radiation spectrum contains doublets of left and right circularly polarized harmonics with high-energy photons in the XUV and soft-x-ray ranges. Our results reveal intriguing and substantially different nonlinear optical responses for homonuclear and heteronuclear diatomic molecules subject to circularly polarized intense laser fields. We study in detail the below- and above-threshold harmonic regions and analyze the ellipticity and phase of the generated harmonic peaks.

  16. Monoenergetic ion beams from ultrathin foils irradiated by ultrahigh-contrast circularly polarized laser pulses

    Directory of Open Access Journals (Sweden)

    O. Klimo

    2008-03-01

    Full Text Available Acceleration of ions from ultrathin foils irradiated by intense circularly polarized laser pulses is investigated using one- and two-dimensional particle simulations. A circularly polarized laser wave heats the electrons much less efficiently than the wave of linear polarization and the ion acceleration process takes place on the front side of the foil. The ballistic evolution of the foil becomes important after all ions contained in the foil have been accelerated. In the ongoing acceleration process, the whole foil is accelerated as a dense compact bunch of quasineutral plasma implying that the energy spectrum of ions is quasimonoenergetic. Because of the ballistic evolution, the velocity spread of an accelerated ion beam is conserved while the average velocity of ions may be further increased. This offers the possibility to control the parameters of the accelerated ion beam. The ion acceleration process is described by the momentum transfer from the laser beam to the foil and it might be fairly efficient in terms of the energy transferred to the heavy ions even if the foil contains a comparable number of light ions or some surface contaminants. Two-dimensional simulations confirm the formation of the quasimonoenergetic spectrum of ions and relatively good collimation of the ion bunch, however the spatial distribution of the laser intensity poses constraints on the maximum velocity of the ion beam. The present ion acceleration mechanism might be suitable for obtaining a dense high energy beam of quasimonoenergetic heavy ions which can be subsequently applied in nuclear physics experiments. Our simulations are complemented by a simple theoretical model which provides the insights on how to control the energy, number, and energy spread of accelerated ions.

  17. Propagation of intense and short circularly polarized pulses in a molecular gas: From multiphoton ionization to nonlinear macroscopic effects

    Science.gov (United States)

    Lytova, M.; Lorin, E.; Bandrauk, A. D.

    2016-07-01

    We present a detailed analysis of the propagation dynamics of short and intense circularly polarized pulses in an aligned diatomic gas. Compared to linearly polarized intense pulses, high harmonic generation (HHG) and the coherent generation of attosecond pulses in the intense-circular-polarization case are a new research area. More specifically, we numerically study the propagation of intense and short circularly polarized pulses in the one-electron H2+ molecular gas, using a micro-macro Maxwell-Schrödinger model. In this model, the macroscopic polarization is computed from the solution of a large number of time-dependent Schrödinger equations, the source of dipole moments, and using a trace operator. We focus on the intensity and the phase of harmonics generated in the H2+ gas as a function of the pulse-propagation distance. We show that short coherent circularly polarized pulses of same helicity can be generated in the molecular gas as a result of cooperative phase-matching effects.

  18. Light in condensed matter in the upper atmosphere as the origin of homochirality: circularly polarized light from Rydberg matter.

    Science.gov (United States)

    Holmlid, Leif

    2009-01-01

    Clouds of the condensed excited Rydberg matter (RM) exist in the atmospheres of comets and planetary bodies (most easily observed at Mercury and the Moon), where they surround the entire bodies. Vast such clouds are recently proposed to exist in the upper atmosphere of Earth (giving rise to the enormous features called noctilucent clouds, polar mesospheric clouds, and polar mesospheric summer radar echoes). It has been shown in experiments with RM that linearly polarized visible light scattered from an RM layer is transformed to circularly polarized light with a probability of approximately 50%. The circular Rydberg electrons in the magnetic field in the RM may be chiral scatterers. The magnetic and anisotropic RM medium acts as a circular polarizer probably by delaying one of the perpendicular components of the light wave. The delay process involved is called Rabi-flopping and gives delays of the order of femtoseconds. This strong effect thus gives intense circularly polarized visible and UV light within RM clouds. Amino acids and other chiral molecules will experience a strong interaction with this light field in the upper atmospheres of planets. The interaction will vary with the stereogenic conformation of the molecules and in all probability promote the survival of one enantiomer. Here, this strong effect is proposed to be the origin of homochirality. The formation of amino acids in the RM clouds is probably facilitated by the catalytic effect of RM.

  19. Photo double ionization of helium 100 eV and 450 eV above threshold: II. Circularly polarized light

    International Nuclear Information System (INIS)

    Knapp, A; Kheifets, A; Bray, I; Weber, Th; Landers, A L; Schoessler, S; Jahnke, T; Nickles, J; Kammer, S; Jagutzki, O; Schmidt, L Ph H; Schoeffler, M; Osipov, T; Prior, M H; Schmidt-Boecking, H; Cocke, C L; Doerner, R

    2005-01-01

    We present a joint experimental and theoretical study of the fully differential cross section of the photo double ionization of helium with left and right circularly polarized light at E exc = 100 eV and 450 eV above the threshold. We analyse angular distributions for the slow electron and the normalized circular dichroism for various energy sharings of the excess energy between the two electrons. The experimental results are well reproduced by convergent close coupling calculations

  20. High-frequency microstrip cross resonators for circular polarization electron paramagnetic resonance spectroscopy.

    Science.gov (United States)

    Henderson, J J; Ramsey, C M; Quddusi, H M; del Barco, E

    2008-07-01

    In this article we discuss the design and implementation of a novel microstrip resonator which allows absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Omega impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled through small gaps to three arms of the cross to connect the resonator to the excitation ports. The control of the relative magnitude and phase between the two microwave stimuli at the input ports of each line allows for tuning the degree and type of polarization of the microwave excitation at the center of the cross resonator. The third (output) port is used to measure the transmitted signal, which is crucial to work at low temperatures, where reflections along lengthy coaxial lines mask the signal reflected by the resonator. Electron paramagnetic resonance spectra recorded at low temperature in an S=5/2 molecular magnet system show that 82% fidelity circular polarization of the microwaves is achieved over the central area of the resonator.

  1. All fiber optics circular-state swept source polarization-sensitive optical coherence tomography.

    Science.gov (United States)

    Lin, Hermann; Kao, Meng-Chun; Lai, Chih-Ming; Huang, Jyun-Cin; Kuo, Wen-Chuan

    2014-02-01

    A swept source (SS)-based circular-state (CS) polarization-sensitive optical coherence tomography (PS-OCT) constructed entirely with polarization-maintaining fiber optics components is proposed with the experimental verification. By means of the proposed calibration scheme, bulk quarter-wave plates can be replaced by fiber optics polarization controllers to, therefore, realize an all-fiber optics CS SSPS-OCT. We also present a numerical dispersion compensation method, which can not only enhance the axial resolution, but also improve the signal-to-noise ratio of the images. We demonstrate that this compact and portable CS SSPS-OCT system with an accuracy comparable to bulk optics systems requires less stringent lens alignment and can possibly serve as a technology to realize PS-OCT instrument for clinical applications (e.g., endoscopy). The largest deviations in the phase retardation (PR) and fast-axis (FA) angle due to sample probe in the linear scanning and a rotation angle smaller than 65 deg were of the same order as those in stationary probe setups. The influence of fiber bending on the measured PR and FA is also investigated. The largest deviations of the PR were 3.5 deg and the measured FA change by ~12 to 21 deg. Finally, in vivo imaging of the human fingertip and nail was successfully demonstrated with a linear scanning probe.

  2. Computational efficiency improvement with Wigner rotation technique in studying atoms in intense few-cycle circularly polarized pulses

    International Nuclear Information System (INIS)

    Yuan, Minghu; Feng, Liqiang; Lü, Rui; Chu, Tianshu

    2014-01-01

    We show that by introducing Wigner rotation technique into the solution of time-dependent Schrödinger equation in length gauge, computational efficiency can be greatly improved in describing atoms in intense few-cycle circularly polarized laser pulses. The methodology with Wigner rotation technique underlying our openMP parallel computational code for circularly polarized laser pulses is described. Results of test calculations to investigate the scaling property of the computational code with the number of the electronic angular basis function l as well as the strong field phenomena are presented and discussed for the hydrogen atom

  3. Time-resolved studies. Ch. 9

    International Nuclear Information System (INIS)

    Mills, Dennis M.; Argonne National Lab., IL

    1991-01-01

    Synchrotron radiation, with its unique properties, offers a tool to extend X-ray measurements from the static to the time-resolved regime. The most straight-forward application of synchrotron radiation to the study of transient phenomena is directly through the possibility of decreased data-collection times via the enormous increase in flux over that of a laboratory X-ray system. Even further increases in intensity can be obtained through the use of novel X-ray optical devices. Wide-bandpass monochromators, e.g., that utilize the continuous spectral distribution of synchrotron radiation, can increase flux on the sample several orders of magnitude over conventional X-ray optical systems thereby allowing a further shortening of the data-collection time. Another approach that uses the continuous spectral nature of synchrotron radiation to decrease data-collection times is the 'parallel data collection' method. Using this technique, intensities as a function of X-ray energy are recorded simultaneously for all energies rather than sequentially recording data at each energy, allowing for a dramatic decrease in data-collection time. Perhaps the most exciting advances in time-resolved X-ray studies will be made by those methods that exploit the pulsed nature of the radiation emitted from storage rings. Pulsed techniques have had an enormous impact in the study of the temporal evolution of transient phenomena. The extension from continuous to modulated sources for use in time-resolved work has been carried over in a host of fields that use both pulsed particle and pulsed electro-magnetic beams. In this chapter the new experimental techniques are reviewed and illustrated with some experiments. (author). 98 refs.; 20 figs.; 5 tabs

  4. Daylight time-resolved photographs of lightning.

    Science.gov (United States)

    Qrville, R E; Lala, G G; Idone, V P

    1978-07-07

    Lightning dart leaders and return strokes have been recorded in daylight with both good spatial resolution and good time resolution as part of the Thunder-storm Research International Program. The resulting time-resolved photographs are apparently equivalent to the best data obtained earlier only at night. Average two-dimensional return stroke velocities in four subsequent strokes between the ground and a height of 1400 meters were approximately 1.3 x 10(8) meters per second. The estimated systematic error is 10 to 15 percent.

  5. Time-resolved x-ray diagnostics

    International Nuclear Information System (INIS)

    Lyons, P.B.

    1981-01-01

    Techniques for time-resolved x-ray diagnostics will be reviewed with emphasis on systems utilizing x-ray diodes or scintillators. System design concerns for high-bandwidth (> 1 GHz) diagnostics will be emphasized. The limitations of a coaxial cable system and a technique for equalizing to improve bandwidth of such a system will be reviewed. Characteristics of new multi-GHz amplifiers will be presented. An example of a complete operational system on the Los Alamos Helios laser will be presented which has a bandwidth near 3 GHz over 38 m of coax. The system includes the cable, an amplifier, an oscilloscope, and a digital camera readout

  6. Circular polarization control for the European XFEL in the soft X-ray regime

    International Nuclear Information System (INIS)

    Geloni, Gianluca; Kocharyan, Vitali; Saldin, Evgeni

    2011-06-01

    The possibility of producing X-ray radiation with high degree of circular polarization is an important asset at XFEL facilities. Polarization control is most important in the soft X-ray region.However, the baseline of the European XFEL, including the soft X-ray SASE3 line, foresees planar undulators only, yielding linearly-polarized radiation. It is clear that the lowest-risk strategy for implementing polarization control at SASE3 involves adding an APPLE II-type undulator at the end of the planar undulator, in order to exploit the micro bunching from the baseline FEL. Detailed experience is available in synchrotron radiation laboratories concerning the manufacturing of 5 m-long APPLE II undulators. However, the choice of a short helical radiator leads to the problem of background suppression. The driving idea of our proposal is that the background radiation can be suppressed by spatial filtering. This operation can be performed by inserting slits behind the APPLE II radiator, where the linearly-polarized radiation spot size is about 30 times larger than the radiation spot size from the helical radiator. The last 7 cells of the SASE3 undulator are left with an open gap in order to provide a total 42 m drift section for electron beam and radiation. Due to the presence of the drift the linearly-polarized radiation spot size increases, and the linearly polarized background radiation can be suppressed by the slits. At the same time, the microbunch structure is easily preserved, so that intense (100 GW) coherent radiation is emitted in the helical radiator. We propose a filtering setup consisting of a pair of water cooled slits for X-ray beam filtering and of a 5 m-long magnetic chicane, which creates an offset for slit installation immediately behind the helical radiator. Electrons and X-rays are separated before the slits by the magnetic chicane, so that the electron beam can pass by the filtering setup without perturbations. Based on start-to-end simulations we

  7. Light-directing omnidirectional circularly polarized reflection from liquid-crystal droplets.

    Science.gov (United States)

    Fan, Jing; Li, Yannian; Bisoyi, Hari Krishna; Zola, Rafael S; Yang, Deng-Ke; Bunning, Timothy J; Weitz, David A; Li, Quan

    2015-02-09

    Constructing and tuning self-organized three-dimensional (3D) superstructures with tailored functionality is crucial in the nanofabrication of smart molecular devices. Herein we fabricate a self-organized, phototunable 3D photonic superstructure from monodisperse droplets of one-dimensional cholesteric liquid crystal (CLC) containing a photosensitive chiral molecular switch with high helical twisting power. The droplets are obtained by a glass capillary microfluidic technique by dispersing into PVA solution that facilitates planar anchoring of the liquid-crystal molecules at the droplet surface, as confirmed by the observation of normal incidence selective circular polarized reflection in all directions from the core of individual droplet. Photoirradiation of the droplets furnishes dynamic reflection colors without thermal relaxation, whose wavelength can be tuned reversibly by variation of the irradiation time. The results provided clear evidence on the phototunable reflection in all directions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Compact circularly polarized truncated square ring slot antenna with suppressed higher resonances.

    Directory of Open Access Journals (Sweden)

    Mursyidul Idzam Sabran

    Full Text Available This paper presents a compact circularly polarized (CP antenna with an integrated higher order harmonic rejection filter. The proposed design operates within the ISM band of 2.32 GHz- 2.63 GHz and is suitable for example for wireless power transfer applications. Asymmetrical truncated edges on a square ring create a defected ground structure to excite the CP property, simultaneously realizing compactness. It offers a 50.5% reduced patch area compared to a conventional design. Novel stubs and slot shapes are integrated in the transmission line to reduce higher (up to the third order harmonics. The proposed prototype yields a -10 dB reflection coefficient (S11 impedance bandwidth of 12.53%, a 3 dB axial ratio bandwidth of 3.27%, and a gain of 5.64 dBi. Measurements also show good agreement with simulations.

  9. CPW-Fed Wideband Circular Polarized Antenna for UHF RFID Applications

    Directory of Open Access Journals (Sweden)

    Sun-Woong Kim

    2017-01-01

    Full Text Available We propose a wide bandwidth antenna with a circular polarization for universal Ultra High Frequency (UHF radio-frequency identification (RFID reader applications. To achieve a wide 3 dB axial ratio (AR bandwidth, three T-shaped microstrip lines are inserted into the ground plane. The measured impedance bandwidth of the proposed antenna is 480 MHz and extends from 660 to 1080 MHz, and the 3 dB AR bandwidth is 350 MHz and extends from 800 to 1155 MHz. The radiation pattern is a bidirectional pattern with a maximum antenna gain of 3.67 dBi. The overall size of the proposed antenna is 114 × 114 × 0.8 mm3.

  10. Photodetachment of F- by a few-cycle circularly polarized laser field

    Science.gov (United States)

    Bivona, Saverio; Burlon, Riccardo; Leone, Claudio

    2006-12-01

    We report on calculations of the above threshold detachment of F- by a few-cycle circularly polarized laser field, discussing the effects of both the carrier-envelope relative phase and the number of the cycle contained in a pulse on the angular distribution of ejected photoelectron. The results are analyzed in terms of a two-step semiclassical model: after the electrons are detached through tunnelling their motion is determined by the electric field pulse according to the classical dynamics laws. Anisotropies in the angular distributions of the electrons ejected on the plane perpendicular to the laser propagation direction are found that depend on the number of cycle of the laser pulse.

  11. Improvement on a 2 × 2 Elements High-Gain Circularly Polarized Antenna Array

    Directory of Open Access Journals (Sweden)

    C. Liu

    2015-01-01

    Full Text Available A novel antipodal Vivaldi antenna with tapering serrated structure at the edges is proposed. Compared with traditional Vivaldi antennas without serrated structure, the gain of the designed antenna is significantly improved in the desired frequency band (4.5–7.5 GHz. In addition, a 2 × 2 Vivaldi antenna array with an orthorhombic structure is designed and fabricated to achieve a circular polarization (CP characteristic. With this configuration, the 3 dB axial ratio bandwidth of the array reaches about 42% with respect to the center frequency of 6 GHz and a high gain is achieved as well. The novel Vivaldi antenna and CP antenna array both have ultrawide band (UWB and high-gain characteristics, which may be applied to the field of commercial communication, remote sensing, and so forth.

  12. Dynamics of ultra-intense circularly polarized solitons under inhomogeneous plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Dong [Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871 (China); Zheng, C. Y.; He, X. T. [Center for Applied Physics and Technology, Peking University, Beijing 100871 (China); Key Laboratory of High Energy Density Physics Simulation, Ministry of Education, Peking University, Beijing 100871 (China); Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)

    2013-06-15

    The dynamics of the ultra-intense circularly polarized solitons under inhomogeneous plasmas are examined. The interaction is modeled by the Maxwell and relativistic hydrodynamic equations and is solved with fully implicit energy-conserving numerical scheme. The soliton is self-consistently generated by the interaction between laser and plasma on the vacuum-plasma interface, and the generation mechanism is well confirmed by two dimensional particle-in-cell simulation. It is shown that a propagating weak soliton can be decreased and reflected by increasing plasma background, which is consistent with the existing studies based on hypothesis of weak density response. However, it is found that ultra-intense soliton is well trapped and kept still when encountering increasing background. Probably, this founding can be applied for trapping and amplifying high-intensity laser-fields.

  13. Gain dynamics of a free-space nitrogen laser pumped by circularly polarized femtosecond laser pulses.

    Science.gov (United States)

    Yao, Jinping; Xie, Hongqiang; Zeng, Bin; Chu, Wei; Li, Guihua; Ni, Jielei; Zhang, Haisu; Jing, Chenrui; Zhang, Chaojin; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

    2014-08-11

    We experimentally demonstrate ultrafast dynamic of generation of the 337-nm nitrogen laser by injecting an external seed pulse into a femtosecond laser filament pumped by a circularly polarized laser pulse. In the pump-probe scheme, it is revealed that the population inversion between the C(3)Π(u) and B(3)Π(g) states of N(2) for the free-space 337-nm laser is firstly built up on the timescale of several picoseconds, followed by a relatively slow decay on the timescale of tens of picoseconds, depending on the nitrogen gas pressure. By measuring the intensities of 337-nm signal from nitrogen gas mixed with different concentrations of oxygen gas, it is also found that oxygen molecules have a significant quenching effect on the nitrogen laser signal. Our experimental observations agree with the picture of electron-impact excitation.

  14. Circularly Polarized Luminescence of Curium: A New Characterization of the 5f Actinide Complexes

    Science.gov (United States)

    Law, Ga-Lai; Andolina, Christopher M.; Xu, Jide; Luu, Vinh; Rutkowski, Philip X.; Muller, Gilles; Shuh, David K.; Gibson, John K.; Raymond, Kenneth N.

    2012-01-01

    A key distinction between the lanthanide (4f) and actinide (5f) transition elements is the increased role of f-orbital covalent bonding in the latter. Circularly polarized luminescence (CPL) is an uncommon but powerful spectroscopy which probes the electronic structure of chiral, luminescent complexes or molecules. While there are many examples of CPL spectra for the lanthanides, this report is the first for an actinide. Two chiral, octadentate chelating ligands based on orthoamide phenol (IAM) were used to complex curium(III). While the radioactivity kept the amount of material limited to micromole amounts, the spectra of the highly luminescent complexes showed significant emission peak-shifts between the different complexes, consistent with ligand field effects previously observed in luminescence spectra. PMID:22920726

  15. Recollision induced excitation-ionization with counter-rotating two-color circularly polarized laser field

    Science.gov (United States)

    Ben, Shuai; Guo, Pei-Ying; Pan, Xue-Fei; Xu, Tong-Tong; Song, Kai-Li; Liu, Xue-Shen

    2017-07-01

    Nonsequential double ionization of Ar by a counter-rotating two-color circularly polarized laser field is theoretically investigated. At the combined intensity in the "knee" structure range, the double ionization occurs mainly through recollision induced excitation followed by subsequent ionization of Ar+∗ . By tracing the history of the recollision trajectories, we explain how the relative intensity ratio of the two colors controls the correlated electron dynamics and optimizes the ionization yields. The major channels contributing to enhancing the double ionization are through the elliptical trajectories with smaller travel time but not through the triangle shape or the other long cycle trajectories. Furthermore, the correlated electron dynamics could be limited to the attosecond time scale by adjusting the relative intensity ratio. Finally, the double ionization from doubly excited complex at low laser intensity is qualitatively discussed.

  16. Oxygen-Bridged Diphenylnaphthylamine as a Scaffold for Full-Color Circularly Polarized Luminescent Materials.

    Science.gov (United States)

    Nishimura, Hidetaka; Tanaka, Kazuo; Morisaki, Yasuhiro; Chujo, Yoshiki; Wakamiya, Atsushi; Murata, Yasujiro

    2017-05-19

    An oxygen-bridged diphenylnaphthylamine with a helical shape was designed and synthesized as a key scaffold for circularly polarized luminescent (CPL) materials. The introduction of electron-withdrawing groups, such as formyl and 2,2-dicyanovinyl substituents at the naphthyl moiety in this skeleton effectively decreases the LUMO level and thus allows a tuning of the band gap. The prepared model compounds exhibit intense CPL signals with a dissymmetry factor (g value) of 10 -3 both in CH 2 Cl 2 solutions and in the solid states. The emission colors of these derivatives are influenced both by the substituents as well as by solvent effects, covering the whole visible region from blue to deep red.

  17. CIRCULARLY POLARIZED SLOTTED APERTURE ANTENNA WITH COPLANAR WAVEGUIDE FED FOR BROADBAND APPLICATIONS

    Directory of Open Access Journals (Sweden)

    B. T. P. MADHAV

    2016-02-01

    Full Text Available Coplanar waveguide fed circularly polarized microstrip patch antenna performance evaluation is presented in this paper. The broadband characteristics are attained by placing open end slot at the lower side of the antenna. The proposed design has the return loss of less than -10dB and VSWR<2 in the desired band of operation. A gain of 3dB to 4dB is attained in the desired band with good radiation characteristics and a suitable axial ratio of less than 3 dB is attained in the prescribed band of operation. Proposed antenna is fabricated on the FR4 substrate with dielectric constant of 4.4. Parametric analysis with change in substrate permittivity also performed and the optimized dimensions are presented in this work.

  18. Classical trajectory analysis of Mg in a circularly polarized laser field

    Science.gov (United States)

    Xu, Tong-Tong; Ben, Shuai; Zhang, Jun; Liu, Xue-Shen

    2017-05-01

    The nonsequential double ionization (NSDI) of Mg atoms is investigated in a circularly polarized laser field using the classical ensemble method. We demonstrate the time evolution of the two-electron energy distribution, the time evolution of the repulsion energy distribution between two electrons in the double ionization process and the time of evolution of the distance distribution between the nucleus and two electrons. The theoretical results indicate that a single recollision leads to the NSDI process. Moreover, we also look into the elliptical trajectories to illustrate the difference in the return process of the first ionized electron. The dependence of the electron momentum distribution on the angle between the momentum and the force of laser field at the time of the first electron is also investigated and the results show that the angle plays a key role in the electron recollision time.

  19. Time Resolved Deposition Measurements in NSTX

    International Nuclear Information System (INIS)

    Skinner, C.H.; Kugel, H.; Roquemore, A.L.; Hogan, J.; Wampler, W.R.

    2004-01-01

    Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen, and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 (micro)g/cm 2 of deposition, however surprisingly, 15.9 (micro)g/cm 2 of material loss occurred at 7 discharges. The net deposited mass of 13.3 (micro)g/cm 2 matched the mass of 13.5 (micro)g/cm 2 measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition

  20. A Study of the use of a Crystal as a `Quarter-Wave Plate' to Produce High Energy Circularly Polarized Photons

    CERN Multimedia

    Kononets, I

    2002-01-01

    %NA59 %title\\\\ \\\\We present a proposal to study the use of a crystal as a `quarter-wave plate' to produce high energy circularly polarized photons, starting from unpolarized electrons. The intention is to generate linearly polarized photons by letting electrons pass a crystalline target, where they interact coherently with the lattice nuclei. The photon polarization is subsequently turned into circular polarization after passing another crystal, which acts as a `quarter-wave plate'.

  1. Unified understanding of tunneling ionization and stabilization of atomic hydrogen in circularly and linearly polarized intense laser fields

    International Nuclear Information System (INIS)

    Miyagi, Haruhide; Someda, Kiyohiko

    2010-01-01

    On the basis of the Floquet formalism, the ionization mechanisms of atomic hydrogen in circularly and linearly polarized intense laser fields are discussed. By using the complex scaling method in the velocity gauge, the pole positions of the scattering-matrix on the complex quasienergy Riemann surface are calculated, and pole trajectories with respect to the variation of the laser intensity are obtained. In the low-frequency regime, the pole trajectory exhibits a smooth ponderomotive energy shift in the case of circular polarization. In contrast, the smoothness is lost in the case of linear polarization. In the high-frequency regime, the pole trajectories exhibit the stabilization phenomenon for both the types of polarization. These observations are elucidated by a unified picture based on the analysis of the adiabatic potentials for the radial motion of the electron in the acceleration gauge. The ionization in the case of circular polarization of the low-frequency regime is governed by the electron tunneling through a barrier of a single adiabatic potential. The stabilization in the high-frequency regime can be explained by the change in the avoided crossings among the adiabatic potential curves. The transition between the different frequency regimes is explicable by the change in the structure of the adiabatic potentials. The difference caused by the type of polarization is ascribable to the difference in the space-time symmetry.

  2. Counterintuitive angular shifts in the photoelectron momentum distribution for atoms in strong few-cycle circularly polarized laser pulses

    DEFF Research Database (Denmark)

    Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2009-01-01

    We solve the three-dimensional time-dependent Schrödinger equation for a three-cycle circularly polarized laser pulse interacting with an atom. The photoelectron momentum distributions show counterintuitive shifts, similar to those observed in a recent experiment (Eckle et al 2008 Science 322 1525...

  3. Time - resolved thermography at Tokamak T-10

    International Nuclear Information System (INIS)

    Grunow, C.; Guenther, K.; Lingertat, J.; Chicherov, V.M.; Evstigneev, S.A.; Zvonkov, S.N.

    1987-01-01

    Thermographic experiments were performed at T-10 tokamak to investigate the thermic coupling of plasma and the limiter. The limiter is an internal equipment of the vacuum vessel of tokamak-type fusion devices and the interaction of plasma with limiter results a high thermal load of limiter for short time. In according to improve the limiter design the temperature distribution on the limiter surface was measured by a time-resolved thermographic method. Typical isotherms and temperature increment curves are presented. This measurement can be used as a systematic plasma diagnostic method because the limiter is installed in the tokamak whereas special additional probes often disturb the plasma discharge. (D.Gy.) 3 refs.; 7 figs

  4. Time-resolved brightness measurements by streaking

    Science.gov (United States)

    Torrance, Joshua S.; Speirs, Rory W.; McCulloch, Andrew J.; Scholten, Robert E.

    2018-03-01

    Brightness is a key figure of merit for charged particle beams, and time-resolved brightness measurements can elucidate the processes involved in beam creation and manipulation. Here we report on a simple, robust, and widely applicable method for the measurement of beam brightness with temporal resolution by streaking one-dimensional pepperpots, and demonstrate the technique to characterize electron bunches produced from a cold-atom electron source. We demonstrate brightness measurements with 145 ps temporal resolution and a minimum resolvable emittance of 40 nm rad. This technique provides an efficient method of exploring source parameters and will prove useful for examining the efficacy of techniques to counter space-charge expansion, a critical hurdle to achieving single-shot imaging of atomic scale targets.

  5. Time-resolved fluoroimmunoassay of CA125

    International Nuclear Information System (INIS)

    Cai Gangming; Huang Biao; Zhu Liguo; Xiao Hualong; Tan Cheng; Tao Yonghui; Jin Jian

    2001-01-01

    A two-site time-resolved fluoroimmunoassay (TRFIA) of CA 125 based on the direct sandwich technique has been developed, with the equilibrium method. The monoclonal antibody (MoAb) against CA 125 was labelled with europium by the help of europium-chelate of diethylenetriaminepentaacetic acid (DTPA). The luminescent enhancement system was an enhancement solution that contained mainly of 2-naphthoyltrifluoroacetone. The intra- and inter- assay CV of the TRFIA were 4.5% and 4.0%, respectively, and the recovery rate was 96.7%, the sensitivity was 3.3 μg/mL. The cross-reacting rate with CEA was negligible, and that with AFP and β-HCG was 4.6% and 12.4%, respectively. Compared with the imported IRMA Kit, the correlation coefficient was 0.999

  6. Circular polarization of γ-quanta radiated in the capture of polarized neutrons by protons and the quark compound bag model

    International Nuclear Information System (INIS)

    Grach, I.L.; Shmatkov, M.Zh.

    1983-01-01

    The circular polarization Psub(γ) of γ-quanta radiated in the capture of polarized neutrons by protons is calculated The contribution of the M1 and E2 radiation of nucleons to Psub(γ) is found using the accurate wave functions of the continuous spectrum. The contribution of the six-quark bag to the polarization Psub(γ) is determined. The value of Psub(γ) is related to the admixture of the 6q-bag in the deuteron. Experimental value of Psub(γ) corresponds to small (< or approximately 0.7%) admixture of the bag

  7. Femtosecond time-resolved ERE-CARS of PM650

    Science.gov (United States)

    He, Ping; Fan, Rongwei; Chen, Deying; Li, Xiaohui; Xia, Yuanqin; Yu, Xin; Wang, Jialing; Jiang, Yugang

    2012-07-01

    We utilize femtosecond time-resolved electronic resonance-enhanced coherent anti-Stokes Raman scattering (ERE-CARS) to investigate new information for pyrromethene 650 (PM650) dye molecules. For this purpose, the vibrational properties of PM650 are registered in diluted solutions of several organisms. We observe a strong Raman vibrational mode with a wavenumber difference of about 48 cm- 1 in its organic solutions. This may be linked to the intramolecular electron transfer (ICT) process from the aromatic ring to the cyano group in PM650. The influence of the solvent effects on the vibrational dynamics of PM650 is also investigated. The vibrational properties of PM650 dye molecules diluted in polar organic solutions are light solvent-dependent.

  8. A helical optical for circular polarized UV-FEL project at the UVSOR

    Energy Technology Data Exchange (ETDEWEB)

    Hama, Hiroyuki [Institute for Molecular Science, Okazaki (Japan)

    1995-12-31

    Most of existing storage ring free electron lasers (SRFEL) are restricted those performances by degradation of mirrors in optical cavities. In general, the SRFEL gain at the short wavelength region with high energy electrons is quite low, and the high reflectivity mirrors such as dielectric multilayer mirrors are therefore required. The mirror degradation is considered as a result of irradiation of higher harmonic photons that are simultaneously emitted from planar optical klystron (OK) type undulators, which are commonly used in SRFEL. This problem is getting severer as the lasing wavelength becomes shorter. The UVSOR-FEL had been originally scheduled to be shutdown by 1996 because another undulator project for spectroscopic studies with circular polarized photon would take the FEL`s place. According to suggestion of the insertion device group of the SPring-8, we have designed a helical undulator that is able to vary degree and direction of the polarization easily. In addition, the undulator can be converted into a helical OK by replacing magnets at the center part of undulator in order to coexist with further FEL experiments. Using a calculated magnetic field for magnet configurations of the OK mode, the radiation spectrum at wide wavelength range was simulated by a Fourier transform of Lienard-Wiechert potentials. As a matter of course, some higher harmonics are radiated on the off-axis angle. However it was found out that the higher harmonics is almost negligible as far as inside a solid angle of the Gaussian laser mode. Moreover the gain at the UV region of 250 nm is expected to be much higher than our present FEL because of high brilliant fundamental radiation. The calculated spatial distribution of higher harmonics and the estimated instantaneous gain is presented. Advantages of the helical OK for SRFEL will be discussed in view of our experience, and a possibility of application two-color experiment with SR will be also mentioned.

  9. Time-Resolved Fluorescence in Photodynamic Therapy

    Directory of Open Access Journals (Sweden)

    Shu-Chi Allison Yeh

    2014-12-01

    Full Text Available Photodynamic therapy (PDT has been used clinically for treating various diseases including malignant tumors. The main advantages of PDT over traditional cancer treatments are attributed to the localized effects of the photochemical reactions by selective illumination, which then generate reactive oxygen species and singlet oxygen molecules that lead to cell death. To date, over- or under-treatment still remains one of the major challenges in PDT due to the lack of robust real-time dose monitoring techniques. Time-resolved fluorescence (TRF provides fluorescence lifetime profiles of the targeted fluorophores. It has been demonstrated that TRF offers supplementary information in drug-molecular interactions and cell responses compared to steady-state intensity acquisition. Moreover, fluorescence lifetime itself is independent of the light path; thus it overcomes the artifacts given by diffused light propagation and detection geometries. TRF in PDT is an emerging approach, and relevant studies to date are scattered. Therefore, this review mainly focuses on summarizing up-to-date TRF studies in PDT, and the effects of PDT dosimetric factors on the measured TRF parameters. From there, potential gaps for clinical translation are also discussed.

  10. Time resolved ion beam induced charge collection

    International Nuclear Information System (INIS)

    Sexton W, Frederick; Walsh S, David; Doyle L, Barney; Dodd E, Paul

    2000-01-01

    Under this effort, a new method for studying the single event upset (SEU) in microelectronics has been developed and demonstrated. Called TRIBICC, for Time Resolved Ion Beam Induced Charge Collection, this technique measures the transient charge-collection waveform from a single heavy-ion strike with a -.03db bandwidth of 5 GHz. Bandwidth can be expanded up to 15 GHz (with 5 ps sampling windows) by using an FFT-based off-line waveform renormalization technique developed at Sandia. The theoretical time resolution of the digitized waveform is 24 ps with data re-normalization and 70 ps without re-normalization. To preserve the high bandwidth from IC to the digitizing oscilloscope, individual test structures are assembled in custom high-frequency fixtures. A leading-edge digitized waveform is stored with the corresponding ion beam position at each point in a two-dimensional raster scan. The resulting data cube contains a spatial charge distribution map of up to 4,096 traces of charge (Q) collected as a function of time. These two dimensional traces of Q(t) can cover a period as short as 5 ns with up to 1,024 points per trace. This tool overcomes limitations observed in previous multi-shot techniques due to the displacement damage effects of multiple ion strikes that changed the signal of interest during its measurement. This system is the first demonstration of a single-ion transient measurement capability coupled with spatial mapping of fast transients

  11. Enzyme reactions and their time resolved measurements

    International Nuclear Information System (INIS)

    Hajdu, Janos

    1990-01-01

    This paper discusses experimental strategies in data collection with the Laue method and summarises recent results using synchrotron radiation. Then, an assessment is made of the progress towards time resolved studies with protein crystals and the problems that remain. The paper consists of three parts which respectively describe some aspects of Laue diffraction, recent examples of structural results from Laue diffraction, and kinetic Laue crystallography. In the first part, characteristics of Laue diffraction is discussed first, focusing on the harmonics problems, spatials problem, wavelength normalization, low resolution hole, data completeness, and uneven coverage of reciprocal space. Then, capture of the symmetry unique reflection set is discussed focusing on the effect of wavelength range on the number of reciprocal lattice points occupying diffracting positions, effect of crystal to film distance and the film area and shape on the number of reflections captured, and effect of crystal symmetry on the number of unique reflections within the number of reflections captured. The second part addresses the determination of the structure of turkey egg white lysozyme, and calcium binding in tomato bushy stunt virus. The third part describes the initiation of reactions in enzyme crystals, picosecond Laue diffraction at high energy storage rings, and detectors. (N.K.)

  12. Asymmetric Vibration of Polar Orthotropic Annular Circular Plates of Quadratically Varying Thickness with Same Boundary Conditions

    Directory of Open Access Journals (Sweden)

    N. Bhardwaj

    2008-01-01

    Full Text Available In the present paper, asymmetric vibration of polar orthotropic annular circular plates of quadratically varying thickness resting on Winkler elastic foundation is studied by using boundary characteristic orthonormal polynomials in Rayleigh-Ritz method. Convergence of the results is tested and comparison is made with results already available in the existing literature. Numerical results for the first ten frequencies for various values of parameters describing width of annular plate, thickness profile, material orthotropy and foundation constant for all three possible combinations of clamped, simply supported and free edge conditions are shown and discussed. It is found that (a higher elastic property in circumferential direction leads to higher stiffness against lateral vibration; (b Lateral vibration characteristics of F-Fplates is more sensitive towards parametric changes in material orthotropy and foundation stiffness than C-C and S-Splates; (c Effect of quadratical thickness variation on fundamental frequency is more significant in cases of C-C and S-S plates than that of F-Fplates. Thickness profile which is convex relative to plate center-line tends to result in higher stiffness of annular plates against lateral vibration than the one which is concave and (d Fundamental mode of vibration of C-C and S-Splates is axisymmetrical while that of F-Fplates is asymmetrical.

  13. Variation in the circularly polarized light reflection of Lomaptera (Scarabaeidae) beetles.

    Science.gov (United States)

    Carter, I E; Weir, K; McCall, M W; Parker, A R

    2016-07-01

    An extended spectroscopic study on the left-through-left circularly polarized reflection spectra of a large number of beetles from the Australasian Scrabaeidae:Cetoniinae of the Lomaptera genus was undertaken. We have obtained a five-category spectral classification. The principal spectral features, which even within the genus range from blue to infrared, are related to structural chirality in the beetle shells. The detailed features of each spectral classification are related to different structural perturbations of the helix, including various pitch values and abrupt twist defects. These spectral characteristics and associated shell structures are confirmed on the basis of simple modelling. An important conclusion from our study is that the simple helical structure resulting in a single symmetric Bragg peak is not the dominant spectral type. Rather the reality is a rich tapestry of spectral types. One intriguing specimen is identified via a scanning electron micrograph to consist of a double interstitial helix leading to a particular double-peak spectrum. © 2016 The Authors.

  14. Circularly Polarized Microstrip Yagi Array Antenna with Wide Beamwidth and High Front-to-Back Ratio

    Directory of Open Access Journals (Sweden)

    Yun Hao

    2016-01-01

    Full Text Available A circularly polarized (CP Microstrip Yagi array antenna (MSYA is designed in order to achieve high front-to-back ratio R(F/B and high gain over wide range in the forward radiation space. A Wilkinson power divider owning two output ways with the same magnitude and different phase is used to feed the antenna. Parametric studies are carried out to investigate the effects of some key geometrical sizes on the antenna’s performance. A prototype of the antenna is fabricated, and good agreement between the measured results and the numerical simulations is observed. The overlap bandwidth of VSWR ≤ 1.5 and AR ≤ 3 dB is about 11%. The steering angle (α between the peak gain direction and the broadside can achieve 35°, R(F/B reaches 19 dB, and the gain at the front point (G0 is only 4.3 dB lower than the maximum gain (Gm. The antenna has a wide beamwidth CP radiation pattern over wide spatial range including 0° ≤ θ ≤ 90° in vertical plane and −35° ≤ φ ≤ 55° in horizontal plane.

  15. Photoinduced electric currents in ring-shaped molecules by circularly polarized laser pulses

    International Nuclear Information System (INIS)

    Nobusada, Katsuyuki; Yabana, Kazuhiro

    2007-01-01

    We have theoretically demonstrated that circularly polarized laser pulses induce electric currents and magnetic moments in ring-shaped molecules Na 10 and benzene. The time-dependent adiabatic local density approximation is employed for this purpose, solving the time-dependent Kohn-Sham equation in real space and real time. It has been found that the electric currents are induced efficiently and persist continuously even after the laser pulses were switched off provided the frequency of the applied laser pulse is in tune with the excitation energy of the electronic excited state with the dipole strength for each molecular system. The electric currents are definitely revealed to be a second-order nonlinear optical response to the magnitude of the electric field. The magnetic dipole moments inevitably accompany the ring currents, so that the molecules are magnetized. The production of the electric currents and the magnetic moments in the present procedure is found to be much more efficient than that utilizing static magnetic fields

  16. Classical radiation effects on relativistic electrons in ultraintense laser fields with circular polarization

    Science.gov (United States)

    Schlegel, Theodor; Tikhonchuk, Vladimir T.

    2012-07-01

    The propagation of a relativistic electron with initial energy ≳100 MeV in a number of simple one-dimensional laser field configurations with circular polarization is studied by solving the relativistic equation of motion in the Landau-Lifschitz approach to account for the radiation friction force. The radiation back-reaction on the electron dynamics becomes visible at dimensionless field amplitudes a ≳ 10 at these high particle energies. Analytical expressions are derived for the energy and the longitudinal momentum of the electron, the frequency shift of the light scattered by the electron and the particle trajectories. These findings are compared with the numerical solutions of the basic equations. A strong radiation damping effect results in reduced light scattering, forming at the same time a broad quasi-continuous spectrum. In addition, the electron dynamics in the strong field of a quasistationary laser piston is investigated. Analytical solutions for the electron trajectories in this complex field pattern are obtained and compared with the numerical solutions. The radiation friction force may stop a relativistic electron after propagation over several laser wavelengths at high laser field strengths, which supports the formation of a stable piston.

  17. Application of circularly polarized laser radiation for sensing of crystal clouds.

    Science.gov (United States)

    Balin, Yurii; Kaul, Bruno; Kokhanenko, Grigorii; Winker, David

    2009-04-13

    The application of circularly polarized laser radiation and measurement of the fourth Stokes parameter of scattered radiation considerably reduce the probability of obtaining ambiguous results for radiation depolarization in laser sensing of crystal clouds. The uncertainty arises when cloud particles appear partially oriented by their large diameters along a certain azimuth direction. Approximately in 30% of all cases, the measured depolarization depends noticeably on the orientation of the lidar reference plane with respect to the particle orientation direction. In this case, the corridor of the most probable depolarization values is about 0.1-0.15, but in individual cases, it can be noticeably wider. The present article considers theoretical aspects of this phenomenon and configuration of a lidar capable of measuring the fourth Stokes parameter together with an algorithm of lidar signal processing in the presence of optically thin cloudiness when molecular scattering cannot be neglected. It is demonstrated that the element ?44 of the normalized backscattering phase matrix (BSPM) can be measured. Results of measurements are independent of the presence or absence of azimuthal particle orientation. For sensing in the zenith or nadir, this element characterizes the degree of horizontal orientation of long particle diameters under the action of aerodynamic forces arising during free fall of particles.

  18. Circularly Polarized Luminescence in Enantiopure Europium and Terbium Complexes with Modular, All-Oxygen Donor Ligands

    Energy Technology Data Exchange (ETDEWEB)

    Seitz, Michael; Do, King; Ingram, Andrew; Moore, Evan; Muller, Gilles; Raymond, Kenneth

    2009-06-04

    The modular syntheses of three new octadentate, enantiopure ligands are reported, one with the bidentate chelating unit 2-hydroxyisophthalamide (IAM) and two with bidentate 1-hydroxy-2-pyridinone (1,2-HOPO) units. A new design principle is introduced for the chiral, non-racemic hexamines which constitute the central backbones for the presented class of ligands. The terbium(III) complex of the IAM ligand, as well as the europium(III) complexes of the 1,2-HOPO ligands, are synthesized and characterized by various techniques (NMR, UV, CD, luminescence spectroscopy). All species exhibit excellent stability and moderate to high luminescence efficiency (quantum yields {phi}{sub Eu} = 0.05-0.08 and {phi}{sub Tb} = 0.30-0.57) in aqueous solution at physiological pH. Special focus is put onto the properties of the complexes in regard to circularly polarized luminescence (CPL). The maximum luminescence dissymmetry factors (glum) in aqueous solution are high with |glum|max = 0.08-0.40. Together with the very favorable general properties (good stability, high quantum yields, long lifetimes), the presented lanthanide complexes can be considered as good candidates for analytical probes based on CPL in biologically relevant environments.

  19. SCRLH-TL Based Sequential Rotation Feed Network for Broadband Circularly Polarized Antenna Array

    Directory of Open Access Journals (Sweden)

    B. F. Zong

    2016-04-01

    Full Text Available In this paper, a broadband circularly polarized (CP microstrip antenna array using composite right/left-handed transmission line (SCRLH-TL based sequential rotation (SR feed network is presented. The characteristics of a SCRLH-TL are initially investigated. Then, a broadband and low insertion loss 45º phase shifter is designed using the SCRLH-TL and the phase shifter is employed in constructing a SR feed network for CP antenna array. To validate the design method of the SR feed network, a 2×2 antenna array comprising sequentially rotated coupled stacked CP antenna elements is designed, fabricated and measured. Both the simulated and measured results indicate that the performances of the antenna element are further enhanced when the SR network is used. The antenna array exhibits the VSWR less than 1.8 dB from 4 GHz to 7 GHz and the 3 dB axial ratio (AR from 4.4 GHz to 6.8 GHz. Also, high peak gain of 13.7 dBic is obtained. Besides, the normalized radiation patterns at the operating frequencies are symmetrical and the side lobe levels are low at φ=0º and φ=90º.

  20. Helical Oligonaphthodioxepins Showing Intense Circularly Polarized Luminescence (CPL) in Solution and in the Solid State.

    Science.gov (United States)

    Takaishi, Kazuto; Yamamoto, Takahiro; Hinoide, Sakiko; Ema, Tadashi

    2017-07-12

    A series of oligonaphthodioxepins was synthesized, revealing a helically arranged octamer, (R,R,R,R,R,R,R)-3, which showed intense circularly polarized luminescence (CPL) both in solution and in the solid state. The fluorescence quantum yields (Φ FL ) in solution and in the solid state were 0.90 and 0.22, respectively, and the g lum values in solution and in the solid state were +2.2×10 -3 and +7.0×10 -3 , respectively. This is one of the highest solid-state CPL g lum values yet reported. The high Φ FL and g lum values were due to the rigidity, as well as to the fact that (R,R,R,R,R,R,R)-3 was a non-planar molecule. Moreover, (R,R,R,R,R,R,R)-3 was highly stable both chemically and stereochemically. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Dynamical behaviour of FEL devices operating with two undulators having opposite circular polarizations

    Energy Technology Data Exchange (ETDEWEB)

    Dattoli, G. [ENEA, Divisione Fisica Applicata, Centro Ricerche Frascati, Rome (Italy); Ottaviani, P.L. [ENEA, Divisione Fisica Applicata, Centro Ricerche, Bologna (Italy); Bucci, L. [ENEA, Guest Rome (Italy)

    2000-07-01

    Optical-Klystron FELs operating with undulators having opposite circular polarizations are characterized by a spontaneous emission spectrum which does not exhibit the characteristic interference pattern. The use of the Madey theorem may allow the conclusion that, for such configuration, the dispersive section does not provide any gain enhancement. In this paper it has been analyzed the problem from a dynamical point of view and clarify how the optical field evolve, what is the role of the bunching and how the consequences of the Madey theorem should be correctly understood. [Italian] Klystron ottici operanti con ondulatori aventi polarizzazione elicoidali opposte, sono caratterizzati da uno spettro di emissione spontanea senza il termine interferenziale dovuto alla sezione dispersiva. L'uso del teorema di Madey indurrebbe alla conclusione che, per una tale configurazione, la sezione dispersiva non induce nessun aumento del guadagno. In questo lavoro analizziamo il problema da un punto di vista dinamico che chiarisce l'evoluzione del campo ottico, quale e' il ruolo del bunching e come le conseguenze del teorema di Madey debbano essere interpretate.

  2. Circularly polarized triple band glass shaped monopole patch antenna with metallic reflector for bluetooth & wireless applications

    Energy Technology Data Exchange (ETDEWEB)

    Jangid, K. G.; Kulhar, V. S. [Department of Physics, Manipal University Jaipur, Jaipur-303007 (India); Choudhary, N.; Jain, P.; Sharma, B. R.; Saini, J. S.; Bhatnagar, D., E-mail: dbhatnagar-2000@rediffmail.com [Microwave Lab, Department of Physics, University of Rajasthan, Jaipur-302004 (India)

    2016-03-09

    This paper presents the design and performance of strip line fed glass shaped monopole patch antenna having with overall size 30mm × 30 mm × 1.59 mm. In the patch; an eight shaped slot and in the ground plane an eight shaped ring are introduced. A metallic ground plane is also introduced at appropriate location beneath the ground plane. The proposed antenna is simulated by applying CST Microwave Studio simulator. Antenna provides circularly polarized radiations, triple broad impedance bandwidth of 203MHz (2.306GHz to 2.510GHz), 42MHz (2.685GHz to 2.757GHz) & GHz (3.63 GHz to 6.05 GHz), high flat gain (close to 5dBi) and good radiation properties in the desired frequency range. This antenna may be a very useful tool for 2.45GHz Bluetooth communication band as well as for 2.4GHz/5.2 GHz /5.8 GHz WLAN bands & 3.7GHz/5.5 GHz Wi-Max bands.

  3. Evidence of a circularly polarized light mode along the optic axis in c-cut NH4H2PO4, induced by circular differential reflection and anomalous birefringence

    International Nuclear Information System (INIS)

    Kaminsky, Werner; Steininger, Steven; Herreros-Cedres, Javier; Glazer, Anthony Michael

    2010-01-01

    The anomalous birefringence and circular differential reflection of NH 4 H 2 PO 4 (4-bar2m), cut on the optic axis, have been found to cause an additional signal in measurements of the optical rotation employing polarized light technology, with the sample between crossed and slightly modulated linear polarizers (tilting high accuracy universal polarimetry). The azimuthal rotation of the linearly polarized light, up to 100 times larger than expected, is described in terms of a circularly polarized light mode along the optic axis of varying amplitude. Experimental evidence leading to our conclusion is given and a qualitative model for the effect is presented.

  4. Low-Gain Circularly Polarized Antenna with Torus-Shaped Pattern

    Science.gov (United States)

    Amaro, Luis R.; Kruid, Ronald C.; Vacchione, Joseph D.; Prata, Aluizio

    2012-01-01

    The Juno mission to Jupiter requires an antenna with a torus-shaped antenna pattern with approximately 6 dBic gain and circular polarization over the Deep Space Network (DSN) 7-GHz transmit frequency and the 8-GHz receive frequency. Given the large distances that accumulate en-route to Jupiter and the limited power afforded by the solar-powered vehicle, this toroidal low-gain antenna requires as much gain as possible while maintaining a beam width that could facilitate a +/-10deg edge of coverage. The natural antenna that produces a toroidal antenna pattern is the dipole, but the limited approx. = 2.2 dB peak gain would be insufficient. Here a shaped variation of the standard bicone antenna is proposed that could achieve the required gains and bandwidths while maintaining a size that was not excessive. The final geometry that was settled on consisted of a corrugated, shaped bicone, which is fed by a WR112 waveguide-to-coaxial- waveguide transition. This toroidal low-gain antenna (TLGA) geometry produced the requisite gain, moderate sidelobes, and the torus-shaped antenna pattern while maintaining a very good match over the entire required frequency range. Its "horn" geometry is also low-loss and capable of handling higher powers with large margins against multipactor breakdown. The final requirement for the antenna was to link with the DSN with circular polarization. A four-layer meander-line array polarizer was implemented; an approach that was fairly well suited to the TLGA geometry. The principal development of this work was to adapt the standard linear bicone such that its aperture could be increased in order to increase the available gain of the antenna. As one increases the aperture of a standard bicone, the phase variation across the aperture begins to increase, so the larger the aperture becomes, the greater the phase variation. In order to maximize the gain from any aperture antenna, the phase should be kept as uniform as possible. Thus, as the standard

  5. Mechanically Reconfigurable Single-Arm Spiral Antenna Array for Generation of Broadband Circularly Polarized Orbital Angular Momentum Vortex Waves.

    Science.gov (United States)

    Li, Long; Zhou, Xiaoxiao

    2018-03-23

    In this paper, a mechanically reconfigurable circular array with single-arm spiral antennas (SASAs) is designed, fabricated, and experimentally demonstrated to generate broadband circularly polarized orbital angular momentum (OAM) vortex waves in radio frequency domain. With the symmetrical and broadband properties of single-arm spiral antennas, the vortex waves with different OAM modes can be mechanically reconfigurable generated in a wide band from 3.4 GHz to 4.7 GHz. The prototype of the circular array is proposed, conducted, and fabricated to validate the theoretical analysis. The simulated and experimental results verify that different OAM modes can be effectively generated by rotating the spiral arms of single-arm spiral antennas with corresponding degrees, which greatly simplify the feeding network. The proposed method paves a reconfigurable way to generate multiple OAM vortex waves with spin angular momentum (SAM) in radio and microwave satellite communication applications.

  6. Circularly polarized microwaves for magnetic resonance study in the GHz range: Application to nitrogen-vacancy in diamonds

    Energy Technology Data Exchange (ETDEWEB)

    Mrózek, M., E-mail: mariusz.mrozek@uj.edu.pl; Rudnicki, D. S.; Gawlik, W. [Institute of Physics, Jagiellonian University, Lojasiewicza 11, 30-348 Krakow (Poland); Mlynarczyk, J. [Department of Electronics, AGH University of Science and Technology, Mickiewicza 30, 30-059 Krakow (Poland)

    2015-07-06

    The ability to create time-dependent magnetic fields of controlled polarization is essential for many experiments with magnetic resonance. We describe a microstrip circuit that allows us to generate strong magnetic field at microwave frequencies with arbitrary adjusted polarization. The circuit performance is demonstrated by applying it to an optically detected magnetic resonance and Rabi nutation experiments in nitrogen-vacancy color centers in diamond. Thanks to high efficiency of the proposed microstrip circuit and degree of circular polarization of 85%; it is possible to address the specific spin states of a diamond sample using a low power microwave generator. The circuit may be applied to a wide range of magnetic resonance experiments with a well-controlled polarization of microwaves.

  7. Study of a filament with a circularly polarized beam at 3.8 cm

    International Nuclear Information System (INIS)

    Straka, R.M.; Papagiannis, M.D.; Kogut, J.A.

    1975-01-01

    Extensive observations of left and right circularly polarized emission were carried out with the 120 ft Haystack antenna, which at 3.8 cm has a HPBW of 4.4 minutes of arc. During a very quite period, September 22-26, 1974, two regions were observed in the southern hemisphere of the sun with brightness temperatures approximately 10% below the surrounding solar disk temperature. Hα photographs show that the main region was associated with a long filament. The separation between the center of the radio depression and the filament increased as the filament advanced toward the limb, with the depression finally disappearing when the filament was at a radial distance >0.8 R(Sun) from the center of the solar disk. These observations are in agreement with a filament model consisting of a thin, tall and exceedingly long sheet of enhanced density encaged in a large and equally long tunnel-like cavity of lower density. The electron density at the 3.8 cm emission level which occurs immediately below the transition zone was estimated to be lower inside the cavity than outside by a factor of 2. The origin of the other depression remains unclear because no relation to any Hα or magnetic feature could be found. A possible association with a coronal hole could not be established because no pertinent EUV or X-ray data were available. It would be of interest to investigate in future observations if a secondary depression is normally associated with the primary depression region over a long filament. (Auth.)

  8. Polarization-dependent atomic dipole traps behind a circular aperture for neutral-atom quantum computing

    International Nuclear Information System (INIS)

    Gillen-Christandl, Katharina; Copsey, Bert D.

    2011-01-01

    The neutral-atom quantum computing community has successfully implemented almost all necessary steps for constructing a neutral-atom quantum computer. We present computational results of a study aimed at solving the remaining problem of creating a quantum memory with individually addressable sites for quantum computing. The basis of this quantum memory is the diffraction pattern formed by laser light incident on a circular aperture. Very close to the aperture, the diffraction pattern has localized bright and dark spots that can serve as red-detuned or blue-detuned atomic dipole traps. These traps are suitable for quantum computing even for moderate laser powers. In particular, for moderate laser intensities (∼100 W/cm 2 ) and comparatively small detunings (∼1000-10 000 linewidths), trap depths of ∼1 mK and trap frequencies of several to tens of kilohertz are achieved. Our results indicate that these dipole traps can be moved by tilting the incident laser beams without significantly changing the trap properties. We also explored the polarization dependence of these dipole traps. We developed a code that calculates the trapping potential energy for any magnetic substate of any hyperfine ground state of any alkali-metal atom for any laser detuning much smaller than the fine-structure splitting for any given electric field distribution. We describe details of our calculations and include a summary of different notations and conventions for the reduced matrix element and how to convert it to SI units. We applied this code to these traps and found a method for bringing two traps together and apart controllably without expelling the atoms from the trap and without significant tunneling probability between the traps. This approach can be scaled up to a two-dimensional array of many pinholes, forming a quantum memory with single-site addressability, in which pairs of atoms can be brought together and apart for two-qubit gates for quantum computing.

  9. Time-resolved fluorescence analysis of the mobile flavin cofactor in ...

    Indian Academy of Sciences (India)

    TECS

    Abstract. Conformational heterogeneity of the FAD cofactor in p-hydroxybenzoate hydroxylase. (PHBH) was investigated with time-resolved polarized flavin fluorescence. For binary enzyme/substrate. (analogue) complexes of wild-type PHBH and Tyr222 mutants, crystallographic studies have revealed two distinct flavin ...

  10. Calcium hydroxylapatite treatment of human skin: evidence of collagen turnover through picrosirius red staining and circularly polarized microscopy

    Directory of Open Access Journals (Sweden)

    Zerbinati N

    2018-01-01

    Full Text Available Nicola Zerbinati,1 Alberto Calligaro2 1Department of Surgical and Morphological Sciences, University of Insubria (Varese and Polyspecialist Medical Center, Pavia, 2Department of Public Health, Experimental and Forensic Medicine, Unit of Histology and Embryology, University of Pavia, Pavia, Italy Background: Calcium hydroxylapatite (CaHA, Radiesse® is a biocompatible, injectable filler for facial soft-tissue augmentation that provides volume to tissues, followed by a process of neocollagenesis for improved skin quality. Objective: To examine the effects of CaHA treatment on the molecular organization of collagen using a combination of picrosirius red staining and circularly polarized light microscopy.Methods: Five subjects received subdermal injection of 0.3 mL of CaHA in tissues scheduled for removal during abdominoplasty 2 months later. Tissue specimens from the CaHA injection site and a control untreated area were obtained from excised skin at the time of surgery. Processed tissue sections were stained with picrosirius red solution 0.1% and visualized under circularly polarized light microscopy for identification of thick mature (type I and thin newly formed (type III collagen fibers. Pixel signals from both the control and CaHA-treated areas were extracted from the images, and morphometric computerized hue analysis was performed to provide a quantitative evaluation of mature and newly formed collagen fibers.Results: Under picrosirius red staining and circularly polarized light microscopy, green/yellow areas (thin newly formed collagen type III were visible among the collagen fibers in tissue sections from the area of CaHA injection. In contrast, the majority of the collagen fibers appeared red (thick mature collagen type I in control tissues. Morphometric analysis confirmed that, following CaHA treatment, the proportion of fibers represented by thin newly formed collagen type III increased significantly (p<0.01 in comparison with the

  11. Generation of azimuthally polarized beams in fast axial flow CO2 laser with hybrid circular subwavelength grating mirror.

    Science.gov (United States)

    Zhao, Jiang; Li, Bo; Zhao, Heng; Wang, Wenjin; Hu, Yi; Liu, Sisi; Wang, Youqing

    2014-06-10

    A hybrid circular subwavelength grating mirror is proposed and fabricated as a rear mirror in a fast axial flow CO2 laser system to generate azimuthally polarized beams (APBs). This grating mirror, with particular gold-covered ridges and nanopillar-stuffed grooves, performs wideband TE wave reflectivity and high polarization selectivity. It shows that the polarization selectivity mechanism lies in the gold ridge's high reflectivity to the TE wave and the lower TM wave reflectivity, which are the result of the mode leaking into substrate through the dielectric-like nanopillar layer. Finally, a high-quality 550 W APB is obtained in subsequent experiments, which provides potential applications in drilling and welding.

  12. Calculation of the vibrationally resolved, circularly polarized luminescence of d-camphorquinone and (S,S)-trans-beta-hydrindanone.

    Science.gov (United States)

    Pritchard, Benjamin; Autschbach, Jochen

    2010-08-02

    Circularly polarized luminescence (CPL), the differential emission of left- and right-handed circularly polarized light from a molecule, is modeled by using time-dependent density functional theory. Calculations of the CPL spectra for the first electronic excited states of d-camphorquinone and (S,S)-trans-beta-hydrindanone under the Franck-Condon approximation and using various functionals are presented, as well as calculations of absorption, emission, and circular dichroism spectra. The functionals B3LYP, BHLYP, and CAM-B3LYP are employed, along with the TZVP and aug-cc-pVDZ Gaussian-type basis sets. For the lowest-energy transitions, all functionals and basis sets perform comparably, with the long-range-corrected CAM-B3LYP better reproducing the excitation energy of camphorquinone but leading to a blue shift with respect to experiment for hydrindanone. The vibrationally resolved spectra of camphorquinone are very well reproduced in terms of peak location, widths, shapes, and intensities. The spectra of hydrindanone are well reproduced in terms of overall envelope shape and width, as well as the lack of prominent vibrational structure in the emission and CPL spectra. Overall the simulated spectra compare well with experiment, and reproduce the band shapes, emission red shifts, and presence or absence of visible vibrational fine structure.

  13. Compact, Highly Efficient, and Fully Flexible Circularly Polarized Antenna Enabled by Silver Nanowires for Wireless Body-Area Networks.

    Science.gov (United States)

    Jiang, Zhi Hao; Cui, Zheng; Yue, Taiwei; Zhu, Yong; Werner, Douglas H

    2017-08-01

    A compact and flexible circularly polarized (CP) wearable antenna is introduced for wireless body-area network systems at the 2.4 GHz industrial, scientific, and medical (ISM) band, which is implemented by employing a low-loss composite of polydimethylsiloxane (PDMS) and silver nanowires (AgNWs). The circularly polarized radiation is enabled by placing a planar linearly polarized loop monopole above a finite anisotropic artificial ground plane. By truncating the anisotropic artificial ground plane to contain only 2 by 2 unit cells, an integrated antenna with a compact form factor of 0.41λ 0 × 0.41λ 0 × 0.045λ 0 is obtained, all while possessing an improved angular coverage of CP radiation. A flexible prototype was fabricated and characterized, experimentally achieving S 11 antenna is compared to a conventional CP patch antenna of the same physical size, which is also comprised of the same PDMS and AgNW composite. The results of this comparison reveal that the proposed antenna has much more stable performance under bending and human body loading, as well as a lower specific absorption rate. In all, the demonstrated wearable antenna offers a compact, flexible, and robust solution which makes it a strong candidate for future integration into body-area networks that require efficient off-body communications.

  14. Time-Resolved Hard X-Ray Spectrometer

    International Nuclear Information System (INIS)

    Kenneth Moya; Ian McKennaa; Thomas Keenana; Michael Cuneob

    2007-01-01

    Wired array studies are being conducted at the SNL Z accelerator to maximize the x-ray generation for inertial confinement fusion targets and high energy density physics experiments. An integral component of these studies is the characterization of the time-resolved spectral content of the x-rays. Due to potential spatial anisotropy in the emitted radiation, it is also critical to diagnose the time-evolved spectral content in a space-resolved manner. To accomplish these two measurement goals, we developed an x-ray spectrometer using a set of high-speed detectors (silicon PIN diodes) with a collimated field-of-view that converged on a 1-cm-diameter spot at the pinch axis. Spectral discrimination is achieved by placing high Z absorbers in front of these detectors. We built two spectrometers to permit simultaneous different angular views of the emitted radiation. Spectral data have been acquired from recent Z shots for the radial and polar views. UNSPEC1 has been adapted to analyze and unfold the measured data to reconstruct the x-ray spectrum. The unfold operator code, UFO2, is being adapted for a more comprehensive spectral unfolding treatment

  15. Natural circular dichroism of amino acid films observed in soft X-ray and VUV region using polarizing undulator

    International Nuclear Information System (INIS)

    Nakagawa, K.; Kaneko, F.; Ohta, Y.; Tanaka, M.; Kitada, T.; Agui, A.; Fujii, F.; Yokoya, A.; Yagi-Watanabe, K.; Yamada, T.

    2005-01-01

    We observed the natural circular dichroism NCD of amino acid films in the soft X-ray region for the first time [M. Tanaka, K. Nakagawa, A. Agui, K. Fujii, A. Yokoya, Physica Scripta, in press]. Based on the success, a new generation of detection system is now under preparation. Vacuum ultraviolet NCD of amino acid films was measured successfully using a polarizing undulator [H. Onuki, Nucl. Instrum. Meth. A 246 (1986) 94] installed at the TERAS electron storage ring at AIST, Tsukuba, Japan. A result of NCD measurement for alanine films is described in detail

  16. Extended high circular polarization in the Orion massive star forming region: implications for the origin of homochirality in the solar system.

    Science.gov (United States)

    Fukue, Tsubasa; Tamura, Motohide; Kandori, Ryo; Kusakabe, Nobuhiko; Hough, James H; Bailey, Jeremy; Whittet, Douglas C B; Lucas, Philip W; Nakajima, Yasushi; Hashimoto, Jun

    2010-06-01

    We present a wide-field (approximately 6' x 6') and deep near-infrared (K(s) band: 2.14 mum) circular polarization image in the Orion nebula, where massive stars and many low-mass stars are forming. Our results reveal that a high circular polarization region is spatially extended (approximately 0.4 pc) around the massive star-forming region, the BN/KL nebula. However, other regions, including the linearly polarized Orion bar, show no significant circular polarization. Most of the low-mass young stars do not show detectable extended structure in either linear or circular polarization, in contrast to the BN/KL nebula. If our solar system formed in a massive star-forming region and was irradiated by net circularly polarized radiation, then enantiomeric excesses could have been induced, through asymmetric photochemistry, in the parent bodies of the meteorites and subsequently delivered to Earth. These could then have played a role in the development of biological homochirality on Earth.

  17. Ionization of one- and three-dimensionally-oriented asymmetric-top molecules by intense circularly polarized femtosecond laser pulses

    DEFF Research Database (Denmark)

    Hansen, Jonas Lerche; Holmegaard, Lotte; Kalhøj, Line

    2011-01-01

    are quantum-state selected using a deflector and three-dimensionally (3D) aligned and oriented adiabatically using an elliptically polarized laser pulse in combination with a static electric field. A characteristic splitting in the molecular frame photoelectron momentum distribution reveals the position......We present a combined experimental and theoretical study on strong-field ionization of a three-dimensionally-oriented asymmetric top molecule, benzonitrile (C7H5N), by circularly polarized, nonresonant femtosecond laser pulses. Prior to the interaction with the strong field, the molecules...... of the nodal planes of the molecular orbitals from which ionization occurs. The experimental results are supported by a theoretical tunneling model that includes and quantifies the splitting in the momentum distribution. The focus of the present article is to understand strong-field ionization from 3D...

  18. Time-resolved X-ray transmission microscopy on magnetic microstructures

    International Nuclear Information System (INIS)

    Puzic, Aleksandar

    2007-01-01

    Three excitation schemes were designed for stroboscopic imaging of magnetization dynamics with time-resolved magnetic transmission X-ray microscopy (TR-MTXM). These techniques were implemented into two types of X-ray microscopes, namely the imaging transmission X-ray microscope (ITXM) and the scanning transmission X-ray microscope (STXM), both installed at the electron storage ring of the Advanced Light Source in Berkeley, USA. Circular diffraction gratings (Fresnel zone plates) used in both microscopes as focusing and imaging elements presently allow for lateral resolution down to 30 nm. Magnetic imaging is performed by using the X-ray magnetic circular dichroism (XMCD) as element specific contrast mechanism. The developed methods have been successfully applied to the experimental investigation of magnetization dynamics in ferromagnetic microstructures. A temporal resolution well below 100 ps was achieved. A conventional pump-probe technique was implemented first. The dynamic response of the magnetization excited by a broadband pulsed magnetic field was imaged spatially resolved using focused X-ray flashes. As a complementary method, the spatially resolved ferromagnetic resonance (SR-FMR) technique was developed for experimental study of magnetization dynamics in the frequency domain. As a third excitation mode, the burst excitation was implemented. The performance and efficiency of the developed methods have been demonstrated by imaging the local magnetization dynamics in laterally patterned ferromagnetic thin-film elements and three-layer stacks. The existence of multiple eigenmodes in the excitation spectra of ferromagnetic microstructures has been verified by using the pump-probe technique. Magnetostatic spin waves were selectively excited and detected with a time resolution of 50 ps using the SR-FMR technique. Thorough analysis of 20 in most cases independently prepared samples has verified that vortices which exhibit a low-amplitude switching of their core

  19. Time-resolved X-ray transmission microscopy on magnetic microstructures; Zeitaufloesende Roentgentransmissionsmikroskopie an magnetischen Mikrostrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Puzic, Aleksandar

    2007-10-23

    Three excitation schemes were designed for stroboscopic imaging of magnetization dynamics with time-resolved magnetic transmission X-ray microscopy (TR-MTXM). These techniques were implemented into two types of X-ray microscopes, namely the imaging transmission X-ray microscope (ITXM) and the scanning transmission X-ray microscope (STXM), both installed at the electron storage ring of the Advanced Light Source in Berkeley, USA. Circular diffraction gratings (Fresnel zone plates) used in both microscopes as focusing and imaging elements presently allow for lateral resolution down to 30 nm. Magnetic imaging is performed by using the X-ray magnetic circular dichroism (XMCD) as element specific contrast mechanism. The developed methods have been successfully applied to the experimental investigation of magnetization dynamics in ferromagnetic microstructures. A temporal resolution well below 100 ps was achieved. A conventional pump-probe technique was implemented first. The dynamic response of the magnetization excited by a broadband pulsed magnetic field was imaged spatially resolved using focused X-ray flashes. As a complementary method, the spatially resolved ferromagnetic resonance (SR-FMR) technique was developed for experimental study of magnetization dynamics in the frequency domain. As a third excitation mode, the burst excitation was implemented. The performance and efficiency of the developed methods have been demonstrated by imaging the local magnetization dynamics in laterally patterned ferromagnetic thin-film elements and three-layer stacks. The existence of multiple eigenmodes in the excitation spectra of ferromagnetic microstructures has been verified by using the pump-probe technique. Magnetostatic spin waves were selectively excited and detected with a time resolution of 50 ps using the SR-FMR technique. Thorough analysis of 20 in most cases independently prepared samples has verified that vortices which exhibit a low-amplitude switching of their core

  20. Use of Linear and Circular Polarization: The Secret LCD Screen and 3D Cinema

    Science.gov (United States)

    Richtberg, Stefan; Girwidz, Raimund

    2017-01-01

    References to everyday life are important for teaching physics. Discussing polarization phenomena, liquid crystal displays (LCDs) and 3D cinemas provide such references. In this paper we describe experiments to support students' understanding of linearly polarized light as well as the phenomenon of inverted colors using a secret LCD screen.…

  1. Sub-nanosecond time-resolved near-field scanning magneto-optical microscope.

    Science.gov (United States)

    Rudge, J; Xu, H; Kolthammer, J; Hong, Y K; Choi, B C

    2015-02-01

    We report on the development of a new magnetic microscope, time-resolved near-field scanning magneto-optical microscope, which combines a near-field scanning optical microscope and magneto-optical contrast. By taking advantage of the high temporal resolution of time-resolved Kerr microscope and the sub-wavelength spatial resolution of a near-field microscope, we achieved a temporal resolution of ∼50 ps and a spatial resolution of microscope, the magnetic field pulse induced gyrotropic vortex dynamics occurring in 1 μm diameter, 20 nm thick CoFeB circular disks has been investigated. The microscope provides sub-wavelength resolution magnetic images of the gyrotropic motion of the vortex core at a resonance frequency of ∼240 MHz.

  2. Controlling electron quantum paths for generation of circularly polarized high-order harmonics by H2+ subject to tailored (ω , 2 ω ) counter-rotating laser fields

    Science.gov (United States)

    Heslar, John; Telnov, Dmitry A.; Chu, Shih-I.

    2018-04-01

    Recently, studies of high-order harmonics (HHG) from atoms driven by bichromatic counter-rotating circularly polarized laser fields as a source of coherent circularly polarized extreme ultraviolet (XUV) and soft-x-ray beams in a tabletop-scale setup have received considerable attention. Here, we demonstrate the ability to control the electron recollisions giving three returns per one cycle of the fundamental frequency ω by using tailored bichromatic (ω , 2 ω ) counter-rotating circularly polarized laser fields with a molecular target. The full control of the electronic pathway is first analyzed by a classical trajectory analysis and then extended to a detailed quantum study of H2+ molecules in bichromatic (ω , 2 ω ) counter-rotating circularly polarized laser fields. The radiation spectrum contains doublets of left- and right-circularly polarized harmonics in the XUV ranges. We study in detail the below-, near-, and above-threshold harmonic regions and describe how excited-state resonances alter the ellipticity and phase of the generated harmonic peaks.

  3. PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

    Science.gov (United States)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    out the potential landscape of the system (often a molecule or an atom) under study [4, 5]. However, the dynamical processes might also be induced by the tunnelling process itself [6, 7]. In the field of molecular science, excited single molecule experiments have been especially performed [8]. As a nice example, we refer to the work of Sykes' group [9] on thioether molecular rotors. In addition, several groups explore the possibility of combining time-resolved scanning tunnelling microscopy with optical techniques [10, 11]. Although the majority of studies that have been performed so far focus on rather simple systems under nearly ideal and well-defined conditions, we anticipate that time-resolved scanning tunnelling microscopy can also be applied in other research areas, such as biology and soft condensed matter, where the experimental conditions are often less ideal. We hope that readers will enjoy this collection of papers and that it will trigger them to further explore the possibilities of this simple, but powerful technique. References [1] Besenbacher F, Laegsgaard E and Stengaard I 2005 Mater. Today 8 26 [2] van Houselt A and Zandvliet H J W 2010 Rev. Mod. Phys. 82 1593 [3] Tringides M C and Hupalo M 2010 J. Phys.: Condens. Matter 22 264002 [4] Ronci F, Colonna S, Cricenti A and Le Lay G 2010 J. Phys.: Condens. Matter 22 264003 [5] van Houselt A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264004 [6] Sprodowski C, Mehlhorn M and Morgenstern K 2010 J. Phys.: Condens. Matter 22 264005 [7] Saedi A, Poelsema B and Zandvliet H J W 2010 J. Phys.: Condens. Matter 22 264007 [8] Sloan P A 2010 J. Phys.: Condens. Matter 22 264001 [9] Jewell A D, Tierney H L, Baber A E, Iski E V, Laha M M and Sykes E C H 2010 J. Phys.: Condens. Matter 22 264006 [10] Riedel D 2010 J. Phys.: Condens. Matter 22 264009 [11] Terada Y, Yoshida S, Takeuchi O and Shigekawa H 2010 J. Phys.: Condens. Matter 22 264008

  4. Stopping power and polarization induced in a plasma by a fast charged particle in circular motion

    Energy Technology Data Exchange (ETDEWEB)

    Villo-Perez, Isidro [Departamento de Electronica, Tecnologia de las Computadoras y Proyectos, Universidad Politecnica de Cartagena, Cartagena (Spain); Arista, Nestor R. [Division Colisiones Atomicas, Centro Atomico Bariloche and Instituto Balseiro, Comision Nacional de Energia Atomica, Bariloche (Argentina); Garcia-Molina, Rafael [Departamento de Fisica, Universidad de Murcia, Murcia (Spain)

    2002-03-28

    We describe the perturbation induced in a plasma by a charged particle in circular motion, analysing in detail the evolution of the induced charge, the electrostatic potential and the energy loss of the particle. We describe the initial transitory behaviour and the different ways in which convergence to final stationary solutions may be obtained depending on the basic parameters of the problem. The results for the stopping power show a resonant behaviour which may give place to large stopping enhancement values as compared with the case of particles in straight-line motion with the same linear velocity. The results also explain a resonant effect recently obtained for particles in circular motion in magnetized plasmas. (author)

  5. Motor Oil Classification Based on Time-Resolved Fluorescence

    OpenAIRE

    Mu, Taotao; Chen, Siying; Zhang, Yinchao; Guo, Pan; Chen, He; Meng, Fandong

    2014-01-01

    A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as uniq...

  6. Time-resolved terahertz spectroscopy of semiconductor nanostructures

    DEFF Research Database (Denmark)

    Porte, Henrik

    This thesis describes time-resolved terahertz spectroscopy measurements on various semiconductor nanostructures. The aim is to study the carrier dynamics in these nanostructures on a picosecond timescale. In a typical experiment carriers are excited with a visible or near-infrared pulse...... be signicantly reduced. Besides time-resolved terahertz spectroscopy measurement, optical transmission, Raman spectroscopy, scanning electron microscope, energy dispersive X-ray, and X-ray diffraction spectroscopy experiments on black silicon are presented....

  7. Seventh international conference on time-resolved vibrational spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, R.B.; Martinez, M.A.D.; Shreve, A.; Woodruff, W.H. [comps.

    1997-04-01

    The International Conference on Time-Resolved Vibrational Spectroscopy (TRVS) is widely recognized as the major international forum for the discussion of advances in this rapidly growing field. The 1995 conference was the seventh in a series that began at Lake Placid, New York, 1982. Santa Fe, New Mexico, was the site of the Seventh International Conference on Time-Resolved Vibrational Spectroscopy, held from June 11 to 16, 1995. TRVS-7 was attended by 157 participants from 16 countries and 85 institutions, and research ranging across the full breadth of the field of time-resolved vibrational spectroscopy was presented. Advances in both experimental capabilities for time-resolved vibrational measurements and in theoretical descriptions of time-resolved vibrational methods continue to occur, and several sessions of the conference were devoted to discussion of these advances and the associated new directions in TRVS. Continuing the interdisciplinary tradition of the TRVS meetings, applications of time-resolved vibrational methods to problems in physics, biology, materials science, and chemistry comprised a large portion of the papers presented at the conference.

  8. The effect of the excitation and of the temperature on the photoluminescence circular polarization of AlInAs/AlGaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Sellami, N. [Unite de Recherche de Physique des Semiconducteurs et Capteurs, Institut Preparatoire aux Etudes Scientifiques et Techniques, La Marsa 2070 (Tunisia); Melliti, A., E-mail: adnenmelliti@yahoo.fr [Unite de Recherche de Physique des Semiconducteurs et Capteurs, Institut Preparatoire aux Etudes Scientifiques et Techniques, La Marsa 2070 (Tunisia); Sahli, A.; Maaref, M.A. [Unite de Recherche de Physique des Semiconducteurs et Capteurs, Institut Preparatoire aux Etudes Scientifiques et Techniques, La Marsa 2070 (Tunisia); Testelin, C. [Institut des NanoSciences de Paris, Campus Boucicaut, Universites Paris 6 et 7, CNRS, UMR7588, 140 rue de Lourmel, 75015 Paris (France); Kuszelewiez, R. [Laboratoire de Photonique et Nanostructures, CNRS, UPR 20 (France)

    2009-12-15

    In this paper, we present a study of photoluminescence (PL) from AlInAs/AlGaAs quantum dots (QDs) structures grown by molecular beam epitaxy. Specifically, we describe the effects of the temperature and of the excitation density on the photoluminescence circular polarization. We have found that the circular polarization degree depends on temperature. On the other hand, the study of the excitation density dependent circular polarization PL degree shows that the last increases in the case of the sample of weak dot density. However, in the case of large dot density, it is almost constant in the excitation density range from 0.116 W cm{sup -2} to 9 W cm{sup -2}.

  9. Time-resolved photoluminescence study of CdSe/CdMnS/CdS core/multi-shell nanoplatelets

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, J. R. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Delikanli, S.; Demir, H. V., E-mail: volkan@bilkent.edu.tr [LUMINOUS Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Materials Sciences, Nanyang Technological University, Singapore 639798 (Singapore); Department of Electrical and Electronics Engineering, Department of Physics, UNAM−Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Scrace, T.; Zhang, P.; Norden, T.; Petrou, A., E-mail: petrou@buffalo.edu [Department of Physics, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States); Thomay, T.; Cartwright, A. N. [Department of Electrical Engineering, State University of New York, University at Buffalo, Buffalo, New York 14260 (United States)

    2016-06-13

    We used photoluminescence spectroscopy to resolve two emission features in CdSe/CdMnS/CdS and CdSe/CdS core/multi-shell nanoplatelet heterostructures. The photoluminescence from the magnetic sample has a positive circular polarization with a maximum centered at the position of the lower energy feature. The higher energy feature has a corresponding signature in the absorption spectrum; this is not the case for the low-energy feature. We have also studied the temporal evolution of these features using a pulsed-excitation/time-resolved photoluminescence technique to investigate their corresponding recombination channels. A model was used to analyze the temporal dynamics of the photoluminescence which yielded two distinct timescales associated with these recombination channels. The above results indicate that the low-energy feature is associated with recombination of electrons with holes localized at the core/shell interfaces; the high-energy feature, on the other hand, is excitonic in nature with the holes confined within the CdSe cores.

  10. Time-resolved CIDEP study of the photogenerated camphorquinone radical anion: a case of dual singlet and triplet precursors

    Energy Technology Data Exchange (ETDEWEB)

    Depew, M.C.; Wan, J.K.S.

    1986-12-04

    Photoreduction of camphorquinone in 2-propanol produced electron spin polarized camphorquinone radical anions. The time-resolved electron spin resonance spectra of the spin-polarized radical anions provided the first evidence of dual singlet and triplet precursors in the CIDEP phenomenon. With the results from fluorescence quenching experiments, the time dependence of the CIDEP spectra can be accounted for qualitatively by the changes of the relative contributions to the polarization among the singlet pair, F and triplet pairs, and the triplet mechanisms.

  11. Time-resolved spectroscopy of the probe fluorescence in the study of human blood protein dynamic structure on SR beam

    International Nuclear Information System (INIS)

    Dobretsov, G.E.; Kurek, N.K.; Syrejshchikova, T.I.; Yakimenko, M.N.; Clarke, D.T.; Jones, G.R.; Munro, I.H.

    2000-01-01

    Time-resolved spectroscopy on the SRS of the Daresbury Laboratory was used for the study of the human serum lipoproteins and human blood albumins with fluorescent probes K-37 and K-35, developed in Russia. The probe K-37 was found sensitive to the difference in dynamic properties of the lipid objects. Two sets of the parameters were used for the description of lipid dynamic structure: (1) time-resolved fluorescence spectra and (2) time-resolved fluorescence depolarization as a function of rotational mobility of lipid molecules. Each measured dynamic parameter reflected the monotonous changes of dynamic properties in the range: lipid spheres-very low density lipoproteins-low density lipoproteins-high density lipoproteins-phospholipid liposomes. The range is characterized by the increase of the ratio polar/ nonpolar lipids. Thus, time-resolved fluorescence could be used to detect some structural modifications in lipoproteins related to atherosclerosis and subsequent cardiovascular diseases development

  12. Ionization of oriented targets by intense circularly polarized laser pulses: Imprints of orbital angular nodes in the two-dimensional momentum distribution

    DEFF Research Database (Denmark)

    Martiny, Christian; Abu-Samha, Mahmoud; Madsen, Lars Bojer

    2010-01-01

    We solve the three-dimensional time-dependent Schrödinger equation for a few-cycle circularly polarized femtosecond laser pulse that interacts with an oriented target exemplified by an argon atom, initially in a 3px or 3py state. The photoelectron momentum distributions show distinct signatures......, we show that ionization by a circularly polarized pulse completely maps out the angular nodal structure of the initial state, thus providing a potential tool for studying orbital symmetry in individual systems or during chemical reactions....

  13. Reduction of the Thomson scattering cross-section in a strong circularly polarized light field in plasma with the change of its spectrum

    Science.gov (United States)

    Korobkin, Vladlen V.; Romanovsky, Michael Y.

    1992-06-01

    It is shown that in a strong circularly polarized laser field, classical electron motion around the ions can occur. The non-relativistic scattering by these electrons in plasma has a certain (Thomson) cross-section only in the limit of a very strong field (it is practically the case of relativistic motion of electrons). In a circularly polarized field with an amplitude on the order of the inneratomic one, the cross section of this process is less. In the spectrum that the scattering of this field gives in plasma, there are non-ion satellites along with the basic frequency.

  14. Solid polymer films exhibiting handedness-switchable, full-color-tunable selective reflection of circularly polarized light.

    Science.gov (United States)

    Nagata, Yuuya; Takagi, Keisuke; Suginome, Michinori

    2014-07-16

    Poly(quinoxaline-2,3-diyl)s bearing (S)-2-methylbutyl, n-butyl, and 8-chlorooctyl groups as side chains were synthesized to fabricate dry solid polymer thin films. These films exhibited selective reflection of right-handed circular polarized light (CPL) in the visible region after annealing in CHCl3 vapor at room temperature. The handedness of reflected CPL was inverted to the left after annealing in 1,2-dichloroethane vapor. It was also found that the color of a particular single film along with the handedness of reflected CPL were fully tuned reversibly, upon exposure of the film to the vapor of various mixtures of chloroform and 1,2-dichloroethane in different ratios.

  15. Coulomb-corrected Volkov-type solution for an electron in an intense circularly polarized laser field

    Science.gov (United States)

    Bauer, Jaroslaw

    2001-04-01

    A simple analytical approximation exists for the wavefunction of an unbound electron interacting both with a strong circularly polarized laser field and an atomic Coulomb potential (Reiss and Krainov 1994 Phys. Rev. A 50 R910). This wavefunction is the Volkov state with a first-order Coulomb correction coming from some perturbative expansion of the potential in the Kramers-Henneberger reference frame. The expansion is valid, if the distance from the centre of the Coulomb force is smaller than the classical radius of motion of a free electron in a plane-wave field. We improve the approximate Coulomb-Volkov wavefunction by including the next term in the perturbative expansion of the atomic potential.

  16. Dual-Band Operation of a Circularly Polarized Four-Arm Curl Antenna with Asymmetric Arm Length

    Directory of Open Access Journals (Sweden)

    Son Xuat Ta

    2016-01-01

    Full Text Available This paper presents dual-band operation of a single-feed composite cavity-backed four-arm curl antenna. Dual-band operation is achieved with the presence of the asymmetrical arm structure. A pair of vacant-quarter printed rings is used in the feed structure to produce a good circular polarization (CP at both bands. The cavity-backed reflector is employed to improve the CP radiation characteristics in terms of the 3-dB axial ratio beamwidth and broadside gain. The proposed antenna is widely applicable in dual-band communication systems that have a small frequency ratio. Examples of such a system are global positioning systems.

  17. The generation of a complete spiral spot and multi split rings by focusing three circularly polarized vortex beams

    Science.gov (United States)

    Chen, Jiannong; Gao, Xiumin; Zhu, Linwei; Xu, Qinfeng; Ma, Wangzi

    2014-05-01

    We demonstrate that a complete right-handed or left-handed spiral-shaped focus can be created by focusing circularly polarized and three spatially shifted vortex beams through high numerical objective. By dividing the back aperture into multi annular zones and applying an additional phase term, the multi focal spots aligned along z axis of individual three dimensional focal shapes can be generated. The spiral shaped focus provides a pathway of manipulating the micro-particles in a curved trajectory and opens up a possibility of measuring mechanical torque of biological large molecules such as DNA by chemically binding one end on the cover-glass. The multi focal spots aligned along the z axis can eliminate the need of z axis scanning in the direct laser writing fabrication of some metamaterials which is composed of three-dimensional array of specific shapes of building blocks.

  18. [A new measurement method of time-resolved spectrum].

    Science.gov (United States)

    Shi, Zhi-gang; Huang, Shi-hua; Liang, Chun-jun; Lei, Quan-sheng

    2007-02-01

    A new method for measuring time-resolved spectrum (TRS) is brought forward. Programming with assemble language controlled the micro-control-processor (AT89C51), and a kind of peripheral circuit constituted the drive circuit, which drived the stepping motor to run the monochromator. So the light of different kinds of expected wavelength could be obtained. The optical signal was transformed to electrical signal by optical-to-electrical transform with the help of photomultiplier tube (Hamamatsu 1P28). The electrical signal of spectrum data was transmitted to the oscillograph. Connecting the two serial interfaces of RS232 between the oscillograph and computer, the electrical signal of spectrum data could be transmitted to computer for programming to draw the attenuation curve and time-resolved spectrum (TRS) of the swatch. The method for measuring time-resolved spectrum (TRS) features parallel measurement in time scale but serial measurement in wavelength scale. Time-resolved spectrum (TRS) and integrated emission spectrum of Tb3+ in swatch Tb(o-BBA)3 phen were measured using this method. Compared with the real time-resolved spectrum (TRS). It was validated to be feasible, credible and convenient. The 3D spectra of fluorescence intensity-wavelength-time, and the integrated spectrum of the swatch Tb(o-BBA)3 phen are given.

  19. Stereo photograph of atomic arrangement by circularly-polarized-light two-dimensional photoelectron spectroscopy

    CERN Document Server

    Daimon, H

    2003-01-01

    A stereo photograph of atomic arrangement was obtained for the first time. The stereo photograph was displayed directly on the screen of display-type spherical-mirror analyzer without any computer-aided conversion process. This stereo photography was realized taking advantage of the phenomenon of circular dichroism in photoelectron angular distribution due to the reversal of orbital angular momentum of photoelectrons. The azimuthal shifts of forward focusing peaks in a photoelectron angular distribution pattern taken with left and right helicity light in a special arrangement are the same as the parallaxes in a stereo view of atoms. Hence a stereoscopic recognition of three-dimensional atomic arrangement is possible, when the left eye and the right eye respectively view the two images obtained by left and right helicity light simultaneously.

  20. Bright Linearly and Circularly Polarized Extreme Ultraviolet and Soft X-ray High Harmonics for Absorption Spectroscopy

    Science.gov (United States)

    Fan, Tingting

    High harmonic generation (HHG) is an extreme nonlinear optical process. When implemented in a phase-matched geometry, HHG coherent upconverts femtosecond laser light into coherent "X-ray laser" beams, while retaining excellent spatial and temporal coherence, as well as the polarization state of the driving laser. HHG has a tabletop footprint, with femtosecond to attosecond time resolution, combined with nanometer spatial resolution. As a consequence of these unique capabilities, HHG is now being widely adopted for use in molecular spectroscopy and imaging, materials science, as well as nanoimaging in general. In the first half of this thesis, I demonstrate high flux linearly polarized soft X-ray HHG, driven by a single-stage 10-mJ Ti:sapphire regenerative amplifier at a repetition rate of 1 kHz. I first down-converted the laser to 1.3 mum using an optical parametric amplifier, before up-converting it into the soft X-ray region using HHG in a high-pressure, phase-matched, hollow waveguide geometry. The resulting optimally phase-matched broadband spectrum extends to 200 eV, with a soft X-ray photon flux of > 106 photons/pulse/1% bandwidth at 1 kHz, corresponding to > 109 photons/s/1% bandwidth, or approximately a three orders-of-magnitude increase compared with past work. Using this broad bandwidth X-ray source, I demonstrated X-ray absorption spectroscopy of multiple elements and transitions in molecules in a single spectrum, with a spectral resolution of 0.25 eV, and with the ability to resolve the near edge fine structure. In the second half of this thesis, I discuss how to generate the first bright circularly polarized (CP) soft X-ray HHG and also use them to implement the first tabletop X-ray magnetic circular dichroism (XMCD) measurements. Using counter-rotating CP lasers at 1.3 mum and 0.79 mum, I generated CPHHG with photon energies exceeding 160 eV. The harmonic spectra emerge as a sequence of closely spaced pairs of left and right CP peaks, with energies

  1. Time-Resolved Spectroscopy in Complex Liquids An Experimental Perspective

    CERN Document Server

    Torre, Renato

    2007-01-01

    Time-Resolved Spectroscopy in Complex Liquids introduces current state-of-the-art techniques in the study of complex dynamical problems in liquid phases. With a unique focus on the experimental aspects applied to complex liquids, this volume provides an excellent overview into the quickly emerging field of soft-matter science. Researchers and engineers will find a comprehensive review of current non-linear spectroscopic and optical Kerr effect techniques, in addition to an in-depth look into relaxation dynamics in complex liquids. This volume offers current experimental findings in transient grating spectroscopy and their application to viscoelastic phenomena in glass-formers, dynamics of confined liquid-crystals, and a time-resolved analysis of the host-quest interactions of dye molecules in liquid-crystal matter. Time-Resolved Spectroscopy in Complex Liquids provides a cohesive introduction suitable for individuals involved in this emerging field, complete with the latest experimental procedures of complex ...

  2. High-Frequency Microstrip Cross Resonators for Circular Polarization EPR Spectroscopy

    OpenAIRE

    Henderson, J. J.; Ramsey, C. M.; Quddusi, H. M.; del Barco, E.

    2008-01-01

    In this article we discuss the design and implementation of a novel microstrip resonator which allows for the absolute control of the microwaves polarization degree for frequencies up to 30 GHz. The sensor is composed of two half-wavelength microstrip line resonators, designed to match the 50 Ohms impedance of the lines on a high dielectric constant GaAs substrate. The line resonators cross each other perpendicularly through their centers, forming a cross. Microstrip feed lines are coupled th...

  3. Reduction of the Thompson scattering cross section in a strong circularly polarized light field in a plasma with the change of its spectrum. “quantum-classical” electron

    Science.gov (United States)

    Korobkin, V. V.; Romanovsky, M. Yu.

    1992-12-01

    It is shown that in a strong circularly polarized laser field a classical electron motion around ions can occur. The scattering of these electrons in a plasma has the Thompson cross section in the limit of strongs field only and for a subrelativistic motion of the electrons. There are non-ion satellites apart from the basic frequency in the scattering spectrum.

  4. Generation of Bright Phase-matched Circularly-polarized Extreme Ultraviolet High Harmonics

    Science.gov (United States)

    2014-12-08

    the first experiment, the HHG beam was spectrally dispersed using a spectrometer com- posed of a toroidal mirror, a laminar Au grating with a groove...field of the foil. The alternating polarity of the CCD Grating Toroid Magnetic foil Electro- magnet Al filter λ = 790 nm, 40 fs, 4 kHz, 10 W λ/2 λ/2 λ/4...our spectrometer. The spectrometer consists of a toroid mirror (glass substrate coated by 100 nm of B4C and tilted at a grazing angle of 8°), a

  5. Solvent sorting in (mixed solvent electrolyte) systems: Time-resolved ...

    Indian Academy of Sciences (India)

    Solvent sorting in (mixed solvent electrolyte) systems: Time-resolved ... Mixed solvent systems; electrolyte solutions; dynamic fluorescence measurements; theory. 1. ..... Open and filled triangles represent τs for the other binary mixture in the absence and presence of 1.0 M LiClO4, respectively. exponentially with the mole ...

  6. On the interpretation of time-resolved anisotropic diffraction patterns

    DEFF Research Database (Denmark)

    Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2010-01-01

    In this paper, we review existing systematic treatments for the interpretation of anisotropic diffraction patterns from partially aligned symmetric top molecules. Such patterns arise in the context of time-resolved diffraction experiments. We calculate diffraction patterns for ground-state Na...

  7. Time resolved spectroscopy of GRB 030501 using INTEGRAL

    DEFF Research Database (Denmark)

    Beckmann, V.; Borkowski, J.; Courvoisier, T.J.L.

    2003-01-01

    The gamma-ray instruments on-board INTEGRAL offer an unique opportunity to perform time resolved analysis on GRBs. The imager IBIS allows accurate positioning of GRBs and broad band spectral analysis, while SPI provides high resolution spectroscopy. GRB 030501 was discovered by the INTEGRAL Burst...... the Ulysses and RHESSI experiments....

  8. Time-resolved luminescence from feldspars: New insight into fading

    DEFF Research Database (Denmark)

    Tsukamoto, S.; Denby, P.M.; Murray, A.S.

    2006-01-01

    Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation (lambda = 875 nm). We observe that the relative contribution ...

  9. Time Resolved Broadband Terahertz Relaxation Dynamics of Electron in Water

    DEFF Research Database (Denmark)

    Wang, Tianwu; Iwaszczuk, Krzysztof; Cooke, David G.

    We investigated the transient response of the solvated electron in water ejected by photodetachment from potassium ferrocyanide using time resolved terahertz spectroscopy (TSTS). Ultrabroadband THz transients are generated and detected by a two-color femtosecond-induced air plasma and air biased...

  10. Time-Resolved Small-Angle X-Ray Scattering

    NARCIS (Netherlands)

    ten Elshof, Johan E.; Besselink, R.; Stawski, Tomasz; Castricum, H.L.; Levy, D.; Zayat, M.

    2015-01-01

    This chapter focuses on time-resolved studies of nanostructure development in sol-gel liquids, that is, diluted sols, wet gels, and drying thin fffilms. The most commonly investigated classes of sol-gel materials are silica, organically modified silica, template-directed mesostructured silica,

  11. Multi-frame pyramid correlation for time-resolved PIV

    NARCIS (Netherlands)

    Sciacchitano, A.; Scarano, F.; Wieneke, B.

    2012-01-01

    A novel technique is introduced to increase the precision and robustness of time-resolved particle image velocimetry (TR-PIV) measurements. The innovative element of the technique is the linear combination of the correlation signal computed at different separation time intervals. The domain of the

  12. Optimizing a time-resolved X-ray absorption experiment

    CERN Document Server

    Bressler, C; Chergui, M; Abela, R; Pattison, P

    2001-01-01

    Calculations are presented of the optimum conditions for performing a laser-pump X-ray probe time-resolved X-ray absorption experiment. The results concerning sensitivity and feasibility for implementing the method are illustrated for the case of the nascent I radical environment following I sup - photolysis in H sub 2 O.

  13. Time-Resolved 2PPE and Time-Resolved PEEM as a Probe of LSP's in Silver Nanoparticles

    Directory of Open Access Journals (Sweden)

    D. Bayer

    2008-01-01

    Full Text Available The time-resolved two-photon photoemission technique (TR-2PPE has been applied to study static and dynamic properties of localized surface plasmons (LSP in silver nanoparticles. Laterally, integrated measurements show the difference between LSP excitation and nonresonant single electron-hole pair creation. Studies below the optical diffraction limit were performed with the detection method of time-resolved photoemission electron microscopy (TR-PEEM. This microscopy technique with a resolution down to 40 nm enables a systematic study of retardation effects across single nanoparticles. In addition, as will be shown in this paper, it is a highly sensitive sensor for coupling effects between nanoparticles.

  14. Numerical simulations of time-resolved quantum electronics

    International Nuclear Information System (INIS)

    Gaury, Benoit; Weston, Joseph; Santin, Matthieu; Houzet, Manuel; Groth, Christoph; Waintal, Xavier

    2014-01-01

    Numerical simulation has become a major tool in quantum electronics both for fundamental and applied purposes. While for a long time those simulations focused on stationary properties (e.g. DC currents), the recent experimental trend toward GHz frequencies and beyond has triggered a new interest for handling time-dependent perturbations. As the experimental frequencies get higher, it becomes possible to conceive experiments which are both time-resolved and fast enough to probe the internal quantum dynamics of the system. This paper discusses the technical aspects–mathematical and numerical–associated with the numerical simulations of such a setup in the time domain (i.e. beyond the single-frequency AC limit). After a short review of the state of the art, we develop a theoretical framework for the calculation of time-resolved observables in a general multiterminal system subject to an arbitrary time-dependent perturbation (oscillating electrostatic gates, voltage pulses, time-varying magnetic fields, etc.) The approach is mathematically equivalent to (i) the time-dependent scattering formalism, (ii) the time-resolved non-equilibrium Green’s function (NEGF) formalism and (iii) the partition-free approach. The central object of our theory is a wave function that obeys a simple Schrödinger equation with an additional source term that accounts for the electrons injected from the electrodes. The time-resolved observables (current, density, etc.) and the (inelastic) scattering matrix are simply expressed in terms of this wave function. We use our approach to develop a numerical technique for simulating time-resolved quantum transport. We find that the use of this wave function is advantageous for numerical simulations resulting in a speed up of many orders of magnitude with respect to the direct integration of NEGF equations. Our technique allows one to simulate realistic situations beyond simple models, a subject that was until now beyond the simulation

  15. Use of Time-Resolved Fluorescence to Monitor Bioactive Compounds in Plant Based Foodstuffs

    Directory of Open Access Journals (Sweden)

    M. Adília Lemos

    2015-06-01

    Full Text Available The study of compounds that exhibit antioxidant activity has recently received much interest in the food industry because of their potential health benefits. Most of these compounds are plant based, such as polyphenolics and carotenoids, and there is a need to monitor them from the field through processing and into the body. Ideally, a monitoring technique should be non-invasive with the potential for remote capabilities. The application of the phenomenon of fluorescence has proved to be well suited, as many plant associated compounds exhibit fluorescence. The photophysical behaviour of fluorescent molecules is also highly dependent on their microenvironment, making them suitable probes to monitor changes in pH, viscosity and polarity, for example. Time-resolved fluorescence techniques have recently come to the fore, as they offer the ability to obtain more information, coupled with the fact that the fluorescence lifetime is an absolute measure, while steady state just provides relative and average information. In this work, we will present illustrative time-resolved measurements, rather than a comprehensive review, to show the potential of time-resolved fluorescence applied to the study of bioactive substances. The aim is to help assess if any changes occur in their form, going from extraction via storage and cooking to the interaction with serum albumin, a principal blood transport protein.

  16. Spatially and time resolved kinetics of indirect magnetoexcitons

    Science.gov (United States)

    Hasling, Matthew; Dorow, Chelsey; Calman, Erica; Butov, Leonid; Wilkes, Joe; Campman, Kenneth; Gossard, Arthur

    The small exciton mass and binding energy give the opportunity to realize the high magnetic field regime for excitons in magnetic fields of few Tesla achievable in lab Long lifetimes of indirect exciton give the opportunity to study kinetics of magnetoexciton transport by time-resolved optical imaging of exciton emission. We present spatially and time resolved measurements showing the effect of increased magnetic field on transport of magnetoexcitons. We observe that increased magnetic field leads to slowing down of magnetoexciton transport. Supported by NSF Grant No. 1407277. J.W. was supported by the EPSRC (Grant EP/L022990/1). C.J.D. was supported by the NSF Graduate Research Fellowship Program under Grant No. DGE-1144086.

  17. Time-resolved crystallography using the Hadamard Transform

    Science.gov (United States)

    Yorke, Briony A.; Beddard, Godfrey S.; Owen, Robin L.; Pearson, Arwen R.

    2014-01-01

    A new method for performing time-resolved X-ray crystallographic experiments based on the Hadamard Transform is proposed and demonstrated. The time-resolution is defined by the underlying periodicity of the probe pulse sequence and the signal to noise is greatly improved compared to the fastest experiments depending on a single pulse. This approach is general and equally applicable to any spectroscopic or imaging measurement where the probe can be encoded. PMID:25282611

  18. Theory of time-resolved inelastic x-ray diffraction

    DEFF Research Database (Denmark)

    Lorenz, Ulf; Møller, Klaus Braagaard; Henriksen, Niels Engholm

    2010-01-01

    Starting from a general theory of time-resolved x-ray scattering, we derive a convenient expression for the diffraction signal based on a careful analysis of the relevant inelastic scattering processes. We demonstrate that the resulting inelastic limit applies to a wider variety of experimental...... conditions than similar, previously derived formulas, and it directly allows the application of selection rules when interpreting diffraction signals. Furthermore, we present a simple extension to systems simultaneously illuminated by x rays and a laser beam....

  19. Time-resolved fluorescence methods (IUPAC Technical Report)

    OpenAIRE

    Lemmetyinen, Helge; Tkachenko, Nikolai V.; Valeur, Bernard; Hotta, Jun-ichi; AMELOOT, Marcel; Ernsting, Nikolaus P.; Gustavsson, Thomas; Boens, Noel

    2014-01-01

    This IUPAC Technical Report describes and compares the currently applied methods for measuring and analyzing time-resolved fluorescence traces using phase-modulation fluorometry as well as pulse fluorometry (direct emission decay measurements, single-photon timing, streak camera measurements, fluorescence upconversion, and optical Kerr gating). The paper starts with a brief description of the basic principles for time and frequency domain fluorescence spectroscopy. The fundamental equations a...

  20. Sound Source Investigation by the Time-Resolved Stereoscopic PIV

    OpenAIRE

    尾花, 功一; 店橋, 護; 宮内, 敏雄; Koichi, OBANA; Mamoru, TANAHASHI; Toshio, MIYAUCHI; 東工大院; 東工大院; 東工大院; Dept. of Mechanical and Aerospace Engineering, Tokyo Institute of Technology; Dept. of Mechanical and Aerospace Engineering, Tokyo Institute of Technology; Dept. of Mechanical and Aerospace Engineering, Tokyo Institute of Technology

    2007-01-01

    To reduce aerodynamic sound, investigation of the sound generation mechanism in flow field is very important. The detailed investigation of the sound source requires velocity measurements with high temporal and spatial resolution and the development of sound source exploration. In this study, sound source in the turbulent mixing layer have been investigated by the time-resolved stereoscopic particle image velocimetry (TRSPIV). Powell's sound source and Reynolds stress component of the Lighthi...

  1. Time-resolved THz spectroscopy in a parallel plate waveguide

    DEFF Research Database (Denmark)

    Cooke, David; Jepsen, Peter Uhd

    2009-01-01

    We demonstrate time-resolved terahertz spectroscopy inside a novel parallel plate waveguide where one of the metallic plates is replaced by a transparent conducting oxide. Considerable improvements to the waveguide loss coefficient are shown, with a power absorption coefficient of 4cm-1 at 0.5 THz....... The time resolution of the technique is shown to be limited by the spatial excitation profile, which for sharply focused beams can approach ~1 ps time scales....

  2. Time resolved heat exchange in driven quantum systems

    Science.gov (United States)

    Florencia Ludovico, María; Lim, Jong Soo; Moskalets, Michael; Arrachea, Liliana; Sánchez, David

    2014-12-01

    We study time-dependent heat transport in systems composed of a resonant level periodically forced with an external power source and coupled to a fermionic continuum. This simple model contains the basic ingredients to understand time resolved energy exchange in quantum capacitors that behave as single particle emitters. We analyse the behaviour of the dynamic heat current for driving frequencies within the non-adiabatic regime, showing that it does not obey a Joule dissipation law.

  3. Multi-frame pyramid correlation for time-resolved PIV

    Energy Technology Data Exchange (ETDEWEB)

    Sciacchitano, Andrea; Scarano, Fulvio [Delft University of Technology, Faculty of Aerospace Engineering, Delft (Netherlands); Wieneke, Bernhard [LaVision GmbH, Goettingen (Germany)

    2012-10-15

    A novel technique is introduced to increase the precision and robustness of time-resolved particle image velocimetry (TR-PIV) measurements. The innovative element of the technique is the linear combination of the correlation signal computed at different separation time intervals. The domain of the correlation signal resulting from different temporal separations is matched via homothetic transformation prior to the averaging of the correlation maps. The resulting ensemble-averaged correlation function features a significantly higher signal-to-noise ratio and a more precise velocity estimation due to the evaluation of a larger particle image displacement. The method relies on a local optimization of the observation time between snapshots taking into account the local out-of-plane motion, continuum deformation due to in-plane velocity gradient and acceleration errors. The performance of the pyramid correlation algorithm is assessed on a synthetically generated image sequence reproducing a three-dimensional Batchelor vortex; experiments conducted in air and water flows are used to assess the performance on time-resolved PIV image sequences. The numerical assessment demonstrates the effectiveness of the pyramid correlation technique in reducing both random and bias errors by a factor 3 and one order of magnitude, respectively. The experimental assessment yields a significant increase of signal strength indicating enhanced measurement robustness. Moreover, the amplitude of noisy fluctuations is considerably attenuated and higher precision is obtained for the evaluation of time-resolved velocity and acceleration. (orig.)

  4. Protons and electrons generated from a 5-{mu}m thick copper tape target irradiated by s-, circularly-, and p-polarized 55-fs laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Li, Z. [Advanced Photon Research Center, Japan Atomic Energy Agency, Umeimidai 8-1, Kizu, Kyoto 619-0215 (Japan); National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan)], E-mail: lizhong@sinap.ac.cn; Daido, H. [Advanced Photon Research Center, Japan Atomic Energy Agency, Umeimidai 8-1, Kizu, Kyoto 619-0215 (Japan); Fukumi, A. [Advanced Photon Research Center, Japan Atomic Energy Agency, Umeimidai 8-1, Kizu, Kyoto 619-0215 (Japan); National Institute of Radiological Sciences, Anagawa 4-9-1, Inage, Chiba 263-8555 (Japan); Bulanov, S.V.; Sagisaka, A.; Ogura, K.; Yogo, A.; Nishiuchi, M.; Orimo, S.; Mori, M. [Advanced Photon Research Center, Japan Atomic Energy Agency, Umeimidai 8-1, Kizu, Kyoto 619-0215 (Japan); Oishi, Y.; Nayuki, T.; Fujii, T.; Nemoto, K. [Central Research Institute of Electric Power Industry, Nagasaka 2-6-1, Yokosuka, Kanagawa 240-0196 (Japan); Nakamura, S.; Noda, A. [Institute of Chemical Research, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); Choi, I.W.; Sung, J.H.; Ko, D.-K.; Lee, J. [Advanced Photonics Research Institute, Gwangju Institute of Science and Technology, Gwangju 500-712 (Korea, Republic of)

    2007-10-01

    The angular distribution and energy spectra of energetic protons emitted from a 5-{mu}m thick copper tape target irradiated by p-, circularly-, and s-polarized 55-fs laser pulses with intensity of 8-9x10{sup 18} W/cm{sup 2} are measured. The protons are found in the rear target normal direction while the hot electrons are found in the laser propagation direction. The maximum energy of protons is equal to 1.34 MeV for p-polarized irradiation. The energy spectrum of protons depends strongly on the total amount of electrons but it does not so strongly depend on the electron angular distribution under our experiment conditions. Two-dimensional particle in cell simulations also show the maximal proton acceleration for the p-polarized pulse, less efficient acceleration for the circular polarization, and lower acceleration efficiency in the case of the s-polarization, which is related to the electron acceleration efficiency at the front side of the target.

  5. Helicity-Selective Phase-Matching and Quasi-Phase matching of Circularly Polarized High-Order Harmonics: Towards Chiral Attosecond Pulses

    Science.gov (United States)

    2016-05-23

    used under the terms of the Creative Commons Attribution 3.0 licence . Any further distribution of this work must maintain attribution to the author(s...condition for full phase matching by analyzing the operator that propagates the vec- torial pump field in circularly polarized HHG (we assume nothing about...throughout propagation. It is instructive to obtain the propagation operator that transfer t  E , 0BC ( ) of equation (6) to t  E z,BC ( ) of equation (7

  6. Lucas–Kanade fluid trajectories for time-resolved PIV

    International Nuclear Information System (INIS)

    Yegavian, Robin; Leclaire, Benjamin; Illoul, Cédric; Losfeld, Gilles; Champagnat, Frédéric

    2016-01-01

    We introduce a new method for estimating fluid trajectories in time-resolved PIV. It relies on a Lucas–Kanade paradigm and consists in a simple and direct extension of a two-frame estimation with FOLKI-PIV (Champagnat et al 2011 Exp. Fluids 50 1169–82). The so-called Lucas–Kanade Fluid Trajectories (LKFT) are assumed to be polynomial in time, and are found as the minimizer of a global functional, in which displacements are sought so as to match the intensities of a series of images pairs in the sequence, in the least-squares sense. All pairs involve the central image, similar to other recent time-resolved approaches (FTC (Lynch and Scarano 2013 Meas. Sci. Technol . 24 035305) and FTEE (Jeon et al 2014 Exp. Fluids 55 1–16)). As switching from a two-frame to a time-resolved objective simply amounts to adding terms in a functional, no significant additional algorithmic element is required. Similar to FOLKI-PIV the method is very well suited for GPU acceleration, which is an important feature as computational complexity increases with the image sequence size. Tests on synthetic data exhibiting peak-locking show that increasing the image sequence size strongly reduces both associated bias and random error, and that LKFT has a remaining total error comparable to that of FTEE on this case. Results on case B of the third PIV challenge (Stanislas et al 2008 Exp. Fluids 45 27–71) also show its ability to drastically reduce the error in situations with low signal-to-noise ratio. These results are finally confirmed on experimental images acquired in the near-field of a low Reynolds number jet. Strong reductions in peak-locking, spatial and temporal noise compared to two-frame estimation are also observed, on the displacement components themselves, as well as on spatial or temporal derivatives, such as vorticity and material acceleration. (paper)

  7. Time Resolved X-Ray Scattering of molecules in Solution

    DEFF Research Database (Denmark)

    Brandt van Driel, Tim

    The dissertation describes the use of Time-Resolved X-ray Diffuse Scattering (TR-XDS) to study photo-induced structural changes in molecules in solution. The application of the technique is exemplified with experiments on two bimetallic molecules. The main focus is on the data-flow and process of...... in the purpose built CSPAD detector is presented and applied to the data to highlight the relevance of this work. Thereby showing the ability to capture a molecular movie on the sub-ps time-scale....

  8. Time-resolved explosion of intense-laser-heated clusters

    International Nuclear Information System (INIS)

    Kim, K.Y.; Alexeev, I.; Parra, E.; Milchberg, H.M.

    2003-01-01

    We investigate the femtosecond explosive dynamics of intense laser-heated argon clusters by measuring the cluster complex transient polarizability. The time evolution of the polarizability is characteristic of competition in the optical response between supercritical and subcritical density regions of the expanding cluster. The results are consistent with time-resolved Rayleigh scattering measurements, and bear out the predictions of a recent laser-cluster interaction model [H. M. Milchberg, S. J. McNaught, and E. Parra, Phys. Rev. E 64, 056402 (2001)

  9. Time-resolved photoluminescence spectroscopy of organic-plasmonic hybrids

    DEFF Research Database (Denmark)

    Leißner, Till; Brewer, Jonathan R.; Fiutowski, Jacek

    We study the optical properties of organic thin films and crystalline organic nanofibers as well as their interaction with plasmonic materials by means of laser-scanning fluorescence lifetime imaging microscopy (FLIM) and time-resolved photoluminescence spectroscopy (TR-PLS). The aim of our...... research is to understand and developed organic-plasmonic hybrid systems with tailored optical and plasmonic properties such as wave-guiding, enhance second-harmonic response and lasing. We are able to image, gather information about the fundamental coupling mechanism, as well as study charge...

  10. Development of new devices for time-resolved Raman spectroelectrochemistry

    OpenAIRE

    Ibáñez Martínez, David

    2015-01-01

    La Tesis Doctoral desarrollada por D. David Ibáñez Martínez que lleva por título “Development of new devices for time-resolved Raman spectroelectrochemistry” ha sido realizada en el área de Química Analítica de la Universidad de Burgos y dirigida por los doctores Álvaro Colina Santamaría y Mª Aránzazu Heras Vidaurre. En este trabajo se han desarrollado nuevas celdas y dispositivos espectroelectroquímicos que permiten el estudio tanto de nuevos materiales como de mecanismos químicos de reacció...

  11. Time-resolved photoelectron spectroscopy of nitrobenzene and its aldehydes

    Science.gov (United States)

    Schalk, Oliver; Townsend, Dave; Wolf, Thomas J. A.; Holland, David M. P.; Boguslavskiy, Andrey E.; Szöri, Milan; Stolow, Albert

    2018-01-01

    We report the first femtosecond time-resolved photoelectron spectroscopy study of 2-, 3- and 4-nitrobenzaldehyde (NBA) and nitrobenzene (NBE) in the gas phase upon excitation at 200 nm. In 3- and 4-NBA, the dynamics follow fast intersystem crossing within 1-2 picoseconds. In 2-NBA and NBE, the dynamics are faster (∼ 0.5 ps). 2-NBA undergoes hydrogen transfer similar to solution phase dynamics. NBE either releases NO2 in the excited state or converts internally back to the ground state. We discuss why these channels are suppressed in the other nitrobenzaldehydes.

  12. Time-resolved SERS for characterizing extracellular vesicles

    Science.gov (United States)

    Rojalin, Tatu; Saari, Heikki; Somersalo, Petter; Laitinen, Saara; Turunen, Mikko; Viitala, Tapani; Wachsmann-Hogiu, Sebastian; Smith, Zachary J.; Yliperttula, Marjo

    2017-02-01

    The aim of this work is to develop a platform for characterizing extracellular vesicles (EV) by using gold-polymer nanopillar SERS arrays simultaneously circumventing the photoluminescence-related disadvantages of Raman with a time-resolved approach. EVs are rich of biochemical information reporting of, for example, diseased state of the biological system. Currently, straightforward, label-free and fast EV characterization methods with low sample consumption are warranted. In this study, SERS spectra of red blood cell and platelet derived EVs were successfully measured and their biochemical contents analyzed using multivariate data analysis techniques. The developed platform could be conveniently used for EV analytics in general.

  13. Time Resolved Spectroscopy of MOVPE Grown Narrow Gap Ferromagnetic Semiconductors

    Science.gov (United States)

    Bhowmick, Mithun; Merritt, Travis; Khodaparast, Giti A.; Feeser, Caitlin; Wessels, Bruce W.; McGill, Stephen; Saha, D.; Pan, X.; Sanders, G. D.; Stanton, C. J.

    2011-12-01

    We report on time resolved differential transmission experiments to provide insight into both the time scales and the nature of the microscopic interactions and carrier dynamics in MOVPE grown ferromagnetic InMnAs and InMnSb. Theoretical calculations of the electronic structure for InMnAs are performed using an 8 band kṡp model which includes non-parabolicity of the conduction bands; strong band-mixing of the valence bands; as well as coupling of Mn impurities to the electrons and holes. Our preliminary theoretical results explain the sign change in the differential transmission signal as a function of probe wavelength.

  14. CCD time-resolved photometry of faint cataclysmic variables. III

    Science.gov (United States)

    Howell, Steve B.; Szkody, Paula; Kreidl, Tobias J.; Mason, Keith O.; Puchnarewicz, E. M.

    1990-01-01

    CCD time-resolved photometry in V, B, and near-IR for 17 faint cataclysmic variables (CVs) is presented and analyzed. The data are obtained at Kitt Peak National Observatory, the Perkins reflector, Lowell Observatory, and the Observatorio del Roque de los Muchachos from April-June 1989. The degree of variability and periodicities for the CVs are examined. It is observed that the variability of most of the stars is consistent with CV class behavior. Orbital periods for five CVs are determined, and three potential eclipsing systems are detected.

  15. NON-RACEMIC AMINO ACID PRODUCTION BY ULTRAVIOLET IRRADIATION OF ACHIRAL INTERSTELLAR ICE ANALOGS WITH CIRCULARLY POLARIZED LIGHT

    International Nuclear Information System (INIS)

    De Marcellus, Pierre; Nuevo, Michel; Danger, Gregoire; Deboffle, Dominique; Le Sergeant d'Hendecourt, Louis; Meinert, Cornelia; Filippi, Jean-Jacques; Meierhenrich, Uwe J.; Nahon, Laurent

    2011-01-01

    The delivery of organic matter to the primitive Earth via comets and meteorites has long been hypothesized to be an important source for prebiotic compounds such as amino acids or their chemical precursors that contributed to the development of prebiotic chemistry leading, on Earth, to the emergence of life. Photochemistry of inter/circumstellar ices around protostellar objects is a potential process leading to complex organic species, although difficult to establish from limited infrared observations only. Here we report the first abiotic cosmic ice simulation experiments that produce species with enantiomeric excesses (e.e.'s). Circularly polarized ultraviolet light (UV-CPL) from a synchrotron source induces asymmetric photochemistry on initially achiral inter/circumstellar ice analogs. Enantioselective multidimensional gas chromatography measurements show significant e.e.'s of up to 1.34% for ( 13 C)-alanine, for which the signs and absolute values are related to the helicity and number of CPL photons per deposited molecule. This result, directly comparable with some L excesses measured in meteorites, supports a scenario in which exogenous delivery of organics displaying a slight L excess, produced in an extraterrestrial environment by an asymmetric astrophysical process, is at the origin of biomolecular asymmetry on Earth. As a consequence, a fraction of the meteoritic organic material consisting of non-racemic compounds may well have been formed outside the solar system. Finally, following this hypothesis, we support the idea that the protosolar nebula has indeed been formed in a region of massive star formation, regions where UV-CPL of the same helicity is actually observed over large spatial areas.

  16. Time Resolved FTIR Analysis of Tailpipe Exhaust for Several Automobiles

    Science.gov (United States)

    White, Allen R.; Allen, James; Devasher, Rebecca B.

    2011-06-01

    The automotive catalytic converter reduces or eliminates the emission of various chemical species (e.g. CO, hydrocarbons, etc.) that are the products of combustion from automobile exhaust. However, these units are only effective once they have reached operating temperature. The design and placement of catalytic converters has changed in order to reduce both the quantity of emissions and the time that is required for the converter to be effective. In order to compare the effectiveness of catalytic converters, time-resolved measurements were performed on several vehicles, including a 2010 Toyota Prius, a 2010 Honda Fit, a 1994 Honda Civic, and a 1967 Oldsmobile 442 (which is not equipped with a catalytic converter but is used as a baseline). The newer vehicles demonstrate bot a reduced overall level of CO and hydrocarbon emissions but are also effective more quickly than older units. The time-resolved emissions will be discussed along with the impact of catalytic converter design and location on the measured emissions.

  17. A novel multiplex absorption spectrometer for time-resolved studies

    Science.gov (United States)

    Lewis, Thomas; Heard, Dwayne E.; Blitz, Mark A.

    2018-02-01

    A Time-Resolved Ultraviolet/Visible (UV/Vis) Absorption Spectrometer (TRUVAS) has been developed that can simultaneously monitor absorption at all wavelengths between 200 and 800 nm with millisecond time resolution. A pulsed photolysis laser (KrF 248 nm) is used to initiate chemical reactions that create the target species. The absorption signals from these species evolve as the composition of the gas in the photolysis region changes over time. The instrument can operate at pressures over the range ˜10-800 Torr and can measure time-resolved absorbances systems (in particular the Herriott cell), there are fundamental differences, most notably the ability to adjust each mirror to maximise the overlap between the probe beam and the photolysis laser. Another feature which aids the sensitivity and versatility of the system is the use of 2 high-throughput spectrographs coupled with sensitive line-array CCDs, which can measure absorbance from ˜200 to 800 nm simultaneously. The capability of the instrument is demonstrated via measurements of the absorption spectrum of the peroxy radical, HOCH2CH2O2, and its self-reaction kinetics.

  18. Motor oil classification based on time-resolved fluorescence.

    Science.gov (United States)

    Mu, Taotao; Chen, Siying; Zhang, Yinchao; Guo, Pan; Chen, He; Meng, Fandong

    2014-01-01

    A time-resolved fluorescence (TRF) technique is presented for classifying motor oils. The system is constructed with a third harmonic Nd:YAG laser, a spectrometer, and an intensified charge coupled device (ICCD) camera. Steady-state and time-resolved fluorescence (TRF) measurements are reported for several motor oils. It is found that steady-state fluorescence is insufficient to distinguish the motor oil samples. Then contour diagrams of TRF intensities (CDTRFIs) are acquired to serve as unique fingerprints to identify motor oils by using the distinct TRF of motor oils. CDTRFIs are preferable to steady-state fluorescence spectra for classifying different motor oils, making CDTRFIs a particularly choice for the development of fluorescence-based methods for the discrimination and characterization of motor oils. The two-dimensional fluorescence contour diagrams contain more information, not only the changing shapes of the LIF spectra but also the relative intensity. The results indicate that motor oils can be differentiated based on the new proposed method, which provides reliable methods for analyzing and classifying motor oils.

  19. Time resolved fluorescence of cow and goat milk powder

    Science.gov (United States)

    Brandao, Mariana P.; de Carvalho dos Anjos, Virgílio; Bell., Maria José V.

    2017-01-01

    Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315 nm and the fluorescence intensity decay registered at 468 nm. We observed fluorescence lifetimes of 1.5 ± 0.3, 6.4 ± 0.4 and 18.7 ± 2.5 ns for goat milk powder; and 1.7 ± 0.3, 6.9 ± 0.2 and 29.9 ± 1.6 ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.

  20. Time resolved spectrometry on the CLIC Test Facility 3

    CERN Document Server

    Lefèvre, T; Braun, H H; Bravin, E; Burger, S; Corsini, R; Döbert, Steffen; Dutriat, C; Tecker, F A; Urschütz, Peter; Welsch, C P

    2006-01-01

    The high charge (>6ìC) electron beam produced in the CLIC Test Facility 3 (CTF3) is accelerated in fully beam loaded cavities. To be able to measure the resulting strong transient effects, the time evolution of the beam energy and its energy spread must be determined with at least 50MHz bandwidth. Three spectrometer lines are installed along the linac in order to control and tune the beam. The electrons are deflected by dipole magnets onto Optical Transition Radiation (OTR) screens which are observed by CCD cameras. The measured horizontal beam size is then directly related to the energy spread. In order to provide time-resolved energy spectra, a fraction of the OTR photons is sent onto a multi-channel photomultiplier. The overall setup is described, special focus is given to the design of the OTR screen with its synchrotron radiation shielding. The performance of the time-resolved measurements are discussed in detail. Finally, the limitations of the system, mainly due to radiation problems are discussed.

  1. Reflection of circularly polarized light and the effect of particle distribution on circular dichroism in evaporation induced self-assembled cellulose nanocrystal thin films

    Science.gov (United States)

    Hewson, D.; Vukusic, P.; Eichhorn, S. J.

    2017-06-01

    Evaporation induced self-assembled (EISA) thin films of cellulose nanocrystals (CNCs) have shown great potential for displaying structural colour across the visible spectrum. They are believed primarily to reflect left handed circularly polarised (LCP) light due to their natural tendency to form structures comprising left handed chirality. Accordingly the fabrication of homogenously coloured CNC thin films is challenging. Deposition of solid material towards the edge of a dried droplet, via the coffee-stain effect, is one such difficulty in achieving homogenous colour across CNC films. These effects are most easily observed in films prepared from droplets where observable reflection of visible light is localised around the edge of the dry film. We report here, the observation of both left and right hand circularly polarised (LCP/RCP) light in reflection from distinct separate regions of CNC EISA thin films and we elucidate how these reflections are dependent on the distribution of CNC material within the EISA thin film. Optical models of reflection are presented which are based on structures revealed using high resolution transmission electron microscopy (TEM) images of film cross sections. We have also employed spectroscopic characterisation techniques to evaluate the distribution of solid CNC material within a selection of CNC EISA thin films and we have correlated this distribution with polarised light spectra collected from each film. We conclude that film regions from which RCP light was reflected were associated with lower CNC concentrations and thicker film regions.

  2. Reflection of circularly polarized light and the effect of particle distribution on circular dichroism in evaporation induced self-assembled cellulose nanocrystal thin films

    Directory of Open Access Journals (Sweden)

    D. Hewson

    2017-06-01

    Full Text Available Evaporation induced self-assembled (EISA thin films of cellulose nanocrystals (CNCs have shown great potential for displaying structural colour across the visible spectrum. They are believed primarily to reflect left handed circularly polarised (LCP light due to their natural tendency to form structures comprising left handed chirality. Accordingly the fabrication of homogenously coloured CNC thin films is challenging. Deposition of solid material towards the edge of a dried droplet, via the coffee-stain effect, is one such difficulty in achieving homogenous colour across CNC films. These effects are most easily observed in films prepared from droplets where observable reflection of visible light is localised around the edge of the dry film. We report here, the observation of both left and right hand circularly polarised (LCP/RCP light in reflection from distinct separate regions of CNC EISA thin films and we elucidate how these reflections are dependent on the distribution of CNC material within the EISA thin film. Optical models of reflection are presented which are based on structures revealed using high resolution transmission electron microscopy (TEM images of film cross sections. We have also employed spectroscopic characterisation techniques to evaluate the distribution of solid CNC material within a selection of CNC EISA thin films and we have correlated this distribution with polarised light spectra collected from each film. We conclude that film regions from which RCP light was reflected were associated with lower CNC concentrations and thicker film regions.

  3. Laser induced vaporization time resolved mass spectrometry of refractories

    International Nuclear Information System (INIS)

    Bonnell, D.W.; Schenck, P.K.; Hastie, J.W.

    1988-01-01

    An experimental approach is described which can yield information about refractory surfaces by examining the time history of the gasdynamic process occurring during pulsed Nd/YAG laser induced degradation/vaporization of the surface. Boron nitride (BN) and graphite are considered as example systems. Time resolved mass spectrometric measurements of evolved species permit direct determination of gas species identities and concentration, independent of mass spectral cracking patterns. Of particular note is the observation of local thermodynamic equilibrium in both systems for the observed gas species laser vaporized from surfaces at temperatures of 2900 K (BN) and 3800-4100 K (graphite). Indirect methods of determining surface temperature, as alternatives to direct measurement of radiance temperature, are discussed. Also, a preliminary analysis of time-of-arrival (TOA), data is presented, including discussion of the elimination of amplifier RG response delays convoluted with the TOA data and extraction of true species time-of-arrival distributions

  4. Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Sentef, Michael; Kemper, Alexander F.; Moritz, Brian; Freericks, James K.; Shen, Zhi-Xun; Devereaux, Thomas P.

    2013-12-26

    Nonequilibrium pump-probe time-domain spectroscopies can become an important tool to disentangle degrees of freedom whose coupling leads to broad structures in the frequency domain. Here, using the time-resolved solution of a model photoexcited electron-phonon system, we show that the relaxational dynamics are directly governed by the equilibrium self-energy so that the phonon frequency sets a window for “slow” versus “fast” recovery. The overall temporal structure of this relaxation spectroscopy allows for a reliable and quantitative extraction of the electron-phonon coupling strength without requiring an effective temperature model or making strong assumptions about the underlying bare electronic band dispersion.

  5. Photon-Counting Arrays for Time-Resolved Imaging

    Science.gov (United States)

    Antolovic, I. Michel; Burri, Samuel; Hoebe, Ron A.; Maruyama, Yuki; Bruschini, Claudio; Charbon, Edoardo

    2016-01-01

    The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach. PMID:27367697

  6. Photon-Counting Arrays for Time-Resolved Imaging

    Directory of Open Access Journals (Sweden)

    I. Michel Antolovic

    2016-06-01

    Full Text Available The paper presents a camera comprising 512 × 128 pixels capable of single-photon detection and gating with a maximum frame rate of 156 kfps. The photon capture is performed through a gated single-photon avalanche diode that generates a digital pulse upon photon detection and through a digital one-bit counter. Gray levels are obtained through multiple counting and accumulation, while time-resolved imaging is achieved through a 4-ns gating window controlled with subnanosecond accuracy by a field-programmable gate array. The sensor, which is equipped with microlenses to enhance its effective fill factor, was electro-optically characterized in terms of sensitivity and uniformity. Several examples of capture of fast events are shown to demonstrate the suitability of the approach.

  7. A prototype chopper for synchrotron time-resolved crystallographic measurements

    International Nuclear Information System (INIS)

    Husheer, S. L. G.; Cole, J. M.; D'Almeida, T.; Teat, S. J.

    2010-01-01

    A mechanical x-ray chopper has been designed to perform microsecond time-resolved crystallographic studies at the DIAMOND synchrotron I19 beamline. It consists of two asymmetric absorbers rotating synchronously at frequencies from 0 to 50 Hz in the same direction around a rotation axis that is parallel to the x-ray beam. The duration of the x-ray pulses produced by the chopper is determined by the relative phase between the two blades, which can be adjusted. The chopper system presented in this paper offers a time resolution suitable for conducting in situ experiments that afford the crystal structure of materials while in their transient (>10 μs) photoactivated excited states.

  8. High time resolved electron temperature measurements by using the multi-pass Thomson scattering system in GAMMA 10/PDX

    OpenAIRE

    Yoshikawa, Masayuki; Yasuhara, Ryo; Ohta, Koichi; Chikatsu, Masayuki; Shima, Yoriko; Kohagura, Junko; Sakamoto, Mizuki; Nakashima, Yousuke; Imai, Tsuyoshi; Ichimura, Makoto; Yamada, Ichihiro; Funaba, Hisamichi; Minami, Takashi

    2016-01-01

    High time resolved electron temperature measurements are useful for fluctuation study. A multi-pass Thomson scattering (MPTS) system is proposed for the improvement of both increasing the TS signal intensity and time resolution. The MPTS system in GAMMA 10/PDX has been constructed for enhancing the Thomson scattered signals for the improvement of measurement accuracy. The MPTS system has a polarization-based configuration with an image relaying system. We optimized the image relaying optics f...

  9. The binding of Curcuma longa extract with bovine serum albumin monitored via time-resolved fluorescence.

    Science.gov (United States)

    Lemos, M Adília; Hungerford, Graham

    2013-01-01

    Turmeric (Curcuma longa L.) is obtained from the rhizome of the Zingberaceae family and has a long history as an ingredient in cooking. It has been used as a dye and recently research has concentrated on its possible health benefits, specifically because of its antioxidant activity. The principal compound that is responsible for this activity is curcumin, which is present with the other curcuminoids; demethoxycurcumin and bisdemethoxycurcumin. Curcumin exhibits fluorescence and its photophysics are markedly affected by the polarity, hydrogen bonding and pH. This provides a means to examine its interaction with proteins, which is important if its potential health role is to be fully investigated. In this work, we monitor the binding kinetics using time-resolved fluorescence measurements, enabled by the use of low dead time electronics coupled with a high repetition rate excitation source and time-resolved emission spectra of the extracted curcuminoids upon interaction with bovine serum albumin. From these measurements the decay-associated spectra of the different lifetime components were obtained, which is consistent with reports of more than one binding site. Monitoring changes in these spectra with increasing temperature also allows for the denaturing of the serum albumin to be inferred. © 2013 The American Society of Photobiology.

  10. Time-resolved Chemical Imaging of Molecules by High-order Harmonics and Ultrashort Rescattering Electrons

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chii Dong [Kansas State Univ., Manhattan, KS (United States)

    2016-03-21

    Directly monitoring atomic motion during a molecular transformation with atomic-scale spatio-temporal resolution is a frontier of ultrafast optical science and physical chemistry. Here we provide the foundation for a new imaging method, fixed-angle broadband laser-induced electron scattering, based on structural retrieval by direct one-dimensional Fourier transform of a photoelectron energy distribution observed along the polarization direction of an intense ultrafast light pulse. The approach exploits the scattering of a broadband wave packet created by strong-field tunnel ionization to self-interrogate the molecular structure with picometre spatial resolution and bond specificity. With its inherent femtosecond resolution, combining our technique with molecular alignment can, in principle, provide the basis for time-resolved tomography for multi-dimensional transient structural determination.

  11. Label-Free Toxin Detection by Means of Time-Resolved Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Paul Takhistov

    2010-01-01

    Full Text Available The real-time detection of trace concentrations of biological toxins requires significant improvement of the detection methods from those reported in the literature. To develop a highly sensitive and selective detection device it is necessary to determine the optimal measuring conditions for the electrochemical sensor in three domains: time, frequency and polarization potential. In this work we utilized a time-resolved electrochemical impedance spectroscopy for the detection of trace concentrations of Staphylococcus enterotoxin B (SEB. An anti-SEB antibody has been attached to the nano-porous aluminum surface using 3-aminopropyltriethoxysilane/glutaraldehyde coupling system. This immobilization method allows fabrication of a highly reproducible and stable sensing device. Using developed immobilization procedure and optimized detection regime, it is possible to determine the presence of SEB at the levels as low as 10 pg/mL in 15 minutes.

  12. Nonlinear dynamics of circularly polarized laser pulse propagating in a magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons distributions

    Energy Technology Data Exchange (ETDEWEB)

    Etemadpour, R.; Dorranian, D., E-mail: doran@srbiau.ac.ir [Laser Laboratory, Plasma Physics Research Center, Science and Research Branch, Islamic Azad University, Tehran (Iran, Islamic Republic of); Sepehri Javan, N. [Department of Physics, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil (Iran, Islamic Republic of)

    2016-05-15

    The nonlinear dynamics of a circularly polarized laser pulse propagating in the magnetized plasmas whose constituents are superthermal ions and mixed nonthermal high-energy tail electrons is studied theoretically. A nonlinear equation which describes the dynamics of the slowly varying amplitude is obtained using a relativistic two-fluid model. Based on this nonlinear equation and taking into account some nonlinear phenomena such as modulational instability, self-focusing and soliton formation are investigated. Effect of the magnetized plasma with superthermal ions and mixed nonthermal high-energy tail electrons on these phenomena is considered. It is shown that the nonthermality and superthermality of particles can substantially change the nonlinearity of medium.

  13. Time-resolved photoluminescence of SiOx encapsulated Si

    Science.gov (United States)

    Kalem, Seref; Hannas, Amal; Österman, Tomas; Sundström, Villy

    Silicon and its oxide SiOx offer a number of exciting electrical and optical properties originating from defects and size reduction enabling engineering new electronic devices including resistive switching memories. Here we present the results of photoluminescence dynamics relevant to defects and quantum confinement effects. Time-resolved luminescence at room temperature exhibits an ultrafast decay component of less than 10 ps at around 480 nm and a slower component of around 60 ps as measured by streak camera. Red shift at the initial stages of the blue luminescence decay confirms the presence of a charge transfer to long lived states. Time-correlated single photon counting measurements revealed a life-time of about 5 ns for these states. The same quantum structures emit in near infrared close to optical communication wavelengths. Nature of the emission is described and modeling is provided for the luminescence dynamics. The electrical characteristics of metal-oxide-semiconductor devices were correlated with the optical and vibrational measurement results in order to have better insight into the switching mechanisms in such resistive devices as possible next generation RAM memory elements. ``This work was supported by ENIAC Joint Undertaking and Laser-Lab Europe''.

  14. Time-resolved biophysical approaches to nucleocytoplasmic transport

    Directory of Open Access Journals (Sweden)

    Francesco Cardarelli

    2017-01-01

    Full Text Available Molecules are continuously shuttling across the nuclear envelope barrier that separates the nucleus from the cytoplasm. Instead of being just a barrier to diffusion, the nuclear envelope is rather a complex filter that provides eukaryotes with an elaborate spatiotemporal regulation of fundamental molecular processes, such as gene expression and protein translation. Given the highly dynamic nature of nucleocytoplasmic transport, during the past few decades large efforts were devoted to the development and application of time resolved, fluorescence-based, biophysical methods to capture the details of molecular motion across the nuclear envelope. These methods are here divided into three major classes, according to the differences in the way they report on the molecular process of nucleocytoplasmic transport. In detail, the first class encompasses those methods based on the perturbation of the fluorescence signal, also known as ensemble-averaging methods, which average the behavior of many molecules (across many pores. The second class comprises those methods based on the localization of single fluorescently-labelled molecules and tracking of their position in space and time, potentially across single pores. Finally, the third class encompasses methods based on the statistical analysis of spontaneous fluorescence fluctuations out of the equilibrium or stationary state of the system. In this case, the behavior of single molecules is probed in presence of many similarly-labelled molecules, without dwelling on any of them. Here these three classes, with their respective pros and cons as well as their main applications to nucleocytoplasmic shuttling will be briefly reviewed and discussed.

  15. Time-resolved infrared spectroscopic techniques as applied to Channelrhodopsin

    Directory of Open Access Journals (Sweden)

    Eglof eRitter

    2015-07-01

    Full Text Available Among optogenetic tools, channelrhodopsins, the light gated ion channels of the plasma membrane from green algae, play the most important role. Properties like channel selectivity, timing parameters or color can be influenced by the exchange of selected amino acids. Although widely used, in the field of neurosciences for example, there is still little known about their photocycles and the mechanism of ion channel gating and conductance. One of the preferred methods for these studies is infrared spectroscopy since it allows observation of proteins and their function at a molecular level and in near-native environment. The absorption of a photon in channelrhodopsin leads to retinal isomerization within femtoseconds, the conductive states are reached in the microsecond time scale and the return into the fully dark-adapted state may take more than minutes. To be able to cover all these time regimes, a range of different spectroscopical approaches are necessary. This mini-review focuses on time-resolved applications of the infrared technique to study channelrhodopsins and other light triggered proteins. We will discuss the approaches with respect to their suitability to the investigation of channelrhodopsin and related proteins.

  16. Time-resolved two-photon photoemission from metal surfaces

    CERN Document Server

    Weinelt, M

    2002-01-01

    The Rydberg-like series of image-potential states is a prototype system for loosely bound electrons at a metal surface. The electronic structure and the femtosecond dynamics of these states is studied by high-resolution energy-and time-resolved two-photon photoemission spectroscopy. The electron trapped in the image potential moves virtually freely laterally to the surface where it is subject to inelastic and quasielastic scattering processes which cause decay of population and phase relaxation. The influence of surface corrugation on these processes has been investigated for adsorbates on Cu(001) and stepped Cu(117) and Cu(119) surfaces which are vicinal to Cu(001). The dynamics depend on both the distance of the electron in front of the surface and the parallel momentum. For CO molecules on Cu(001) inelastic scattering into bulk states and adsorbate-induced resonances determine the decay rate. For small numbers of Cu adatoms on Cu(001) and the vicinal surfaces the decay rate of image-potential states is sig...

  17. Quantitative analysis of time-resolved microwave conductivity data

    Science.gov (United States)

    Reid, Obadiah G.; Moore, David T.; Li, Zhen; Zhao, Dewei; Yan, Yanfa; Zhu, Kai; Rumbles, Garry

    2017-12-01

    Flash-photolysis time-resolved microwave conductivity (fp-TRMC) is a versatile, highly sensitive technique for studying the complex photoconductivity of solution, solid, and gas-phase samples. The purpose of this paper is to provide a standard reference work for experimentalists interested in using microwave conductivity methods to study functional electronic materials, describing how to conduct and calibrate these experiments in order to obtain quantitative results. The main focus of the paper is on calculating the calibration factor, K, which is used to connect the measured change in microwave power absorption to the conductance of the sample. We describe the standard analytical formulae that have been used in the past, and compare them to numerical simulations. This comparison shows that the most widely used analytical analysis of fp-TRMC data systematically under-estimates the transient conductivity by ~60%. We suggest a more accurate semi-empirical way of calibrating these experiments. However, we emphasize that the full numerical calculation is necessary to quantify both transient and steady-state conductance for arbitrary sample properties and geometry.

  18. Atlas of time-resolved spectrophotometry of cataclysmic variables

    International Nuclear Information System (INIS)

    Honeycutt, R.K.; Schlegel, E.M.; Kaitchuck, R.H.; Ohio State Univ., Columbus)

    1987-01-01

    Whole-orbit, time-resolved spectrophotometry of 18 cataclysmic variables is reduced and displayed in a homogeneous fashion. Each set of digital data is binned into a phase-dependent gray-scale image which resembles a single-trailed photographic spectrogram. This technique permits convient comparison of phase-dependent spectral changes among the different systems. The approximate wavelength interval 4250-4950 A was observed at 2.5 A resolution. This interval contains the accretion disk emission lines of H-beta, H-gamma, He I 4471 A, and He II 4686 A. A brief commentary on the phenomena that can be seen in the image of each star is given. These effects include orbital motion, line-profile changes during eclipse, and s-waves. Several epochs of data on UX UMa are presented, displaying yearly changes in the spectrum. A series of outburst spectra of RX And are included, showing how phase-dependent spectra evolve during outburst. EX Hya spectra are displayed folded on both the 98 minute and the 67 minute photometric periods. In all, 23 spectral data sets are displayed and discussed for the 18 systems. 53 references

  19. Time-resolved laser-induced fluorescence system

    Science.gov (United States)

    Bautista, F. J.; De la Rosa, J.; Gallegos, F. J.

    2006-02-01

    Fluorescence methods are being used increasingly in the measurement of species concentrations in gases, liquids and solids. Laser induced fluorescence is spontaneous emission from atoms or molecules that have been excited by laser radiation. Here we present a time resolved fluorescence instrument that consists of a 5 μJ Nitrogen laser (337.1 nm), a sample holder, a quartz optical fiber, a spectrometer, a PMT and a PC that allows the measurement of visible fluorescence spectra (350-750 nm). Time response of the system is approximately 5 ns. The instrument has been used in the measurement of colored bond paper, antifreeze, diesel, cochineal pigment and malignant tissues. The data acquisition was achieved through computer control of a digital oscilloscope (using General Purpose Interface Bus GPIB) and the spectrometer via serial (RS232). The instrument software provides a graphic interface that lets make some data acquisition tasks like finding fluorescence spectra, and fluorescence lifetimes. The software was developed using the Lab-View 6i graphic programming package and can be easily managed in order to add more functions to it.

  20. In-pile Thermal Conductivity Characterization with Time Resolved Raman

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xinwei

    2018-03-19

    Executive Summary The project is designed to achieve three objectives: (1) Develop a novel time resolved Raman technology for direct measurement of fuel and cladding thermal conductivity. (2) Validate and improve the technology development by measuring ceramic materials germane to the nuclear industry. (3) Conduct instrumentation development to integrate optical fiber into our sensing system for eventual in-pile measurement. We have developed three new techniques: time-domain differential Raman (TD-Raman), frequency-resolved Raman (FR-Raman), and energy transport state-resolved Raman (ET-Raman). The TD-Raman varies the laser heating time and does simultaneous Raman thermal probing, the FR-Raman probes the material’s thermal response under periodical laser heating of different frequencies, and the ET-Raman probes the thermal response under steady and pulsed laser heating. The measurement capacity of these techniques have been fully assessed and verified by measuring micro/nanoscale materials. All these techniques do not need the data of laser absorption and absolute material temperature rise, yet still be able to measure the thermal conductivity and thermal diffusivity with unprecedented accuracy. It is expected they will have broad applications for in-pile thermal characterization of nuclear materials based on pure optical heating and sensing.

  1. Monitoring tissue metabolism via time-resolved laser fluorescence

    Science.gov (United States)

    Maerz, Holger K.; Buchholz, Rainer; Emmrich, Frank; Fink, Frank; Geddes, Clive L.; Pfeifer, Lutz; Raabe, Ferdinand; Marx, Uwe

    1999-05-01

    Most assays for drug screening are monitoring the metabolism of cells by detecting the NADH content, which symbolize its metabolic activity, indirectly. Nowadays, the performance of a LASER enables us to monitor the metabolic state of mammalian cells directly and on-line by using time-resolved autofluorescence detection. Therefore, we developed in combination with tissue engineering, an assay for monitoring minor toxic effects of volatile organic compounds (VOC), which are accused of inducing Sick Building Syndrome (SBS). Furthermore, we used the Laserfluoroscope (LF) for pharmacological studies on human bone marrow in vitro with special interest in chemotherapy simulation. In cancer research and therapy, the effect of chemostatica in vitro in the so-called oncobiogram is being tested; up to now without great success. However, it showed among other things that tissue structure plays a vital role. Consequently, we succeeded in simulating a chemotherapy in vitro on human bone marrow. Furthermore, after tumor ektomy we were able to distinguish between tumoric and its surrounding healthy tissue by using the LF. With its sensitive detection of metabolic changes in tissues the LF enables a wide range of applications in biotechnology, e.g. for quality control in artificial organ engineering or biocompatability testing.

  2. Time-Resolved Synchronous Fluorescence for Biomedical Diagnosis

    Science.gov (United States)

    Zhang, Xiaofeng; Fales, Andrew; Vo-Dinh, Tuan

    2015-01-01

    This article presents our most recent advances in synchronous fluorescence (SF) methodology for biomedical diagnostics. The SF method is characterized by simultaneously scanning both the excitation and emission wavelengths while keeping a constant wavelength interval between them. Compared to conventional fluorescence spectroscopy, the SF method simplifies the emission spectrum while enabling greater selectivity, and has been successfully used to detect subtle differences in the fluorescence emission signatures of biochemical species in cells and tissues. The SF method can be used in imaging to analyze dysplastic cells in vitro and tissue in vivo. Based on the SF method, here we demonstrate the feasibility of a time-resolved synchronous fluorescence (TRSF) method, which incorporates the intrinsic fluorescent decay characteristics of the fluorophores. Our prototype TRSF system has clearly shown its advantage in spectro-temporal separation of the fluorophores that were otherwise difficult to spectrally separate in SF spectroscopy. We envision that our previously-tested SF imaging and the newly-developed TRSF methods will combine their proven diagnostic potentials in cancer diagnosis to further improve the efficacy of SF-based biomedical diagnostics. PMID:26404289

  3. Ultrasensitive time-resolved immunofluorometric assay of pepsinogen I

    International Nuclear Information System (INIS)

    Huang Biao; Xiao Hualong; Zhang Xiangrui; Zhu Lan; Jiang Menjun

    2004-01-01

    Purpose: To construct a two-site sandwich-type assay for pepsinogen I with time-resolved fluoroimmunoassay (TRFIA) as a detection technique. Methods: On the noncompetitive assay, one monoclonal antibody (McAb) coating on wells directed against a specific antigenic site on the pepsinogen I, the europium-labelled McAb which was prepared by with helpful of the europium-chelate of N-(p-isothiocyanatobenzyl)- diethylenetriamine-N, N, N, N-tetraacetic acid directed against a different antigenic site on the pepsinogen I molecule we called labelling McAb. The luminescent enhancement system was enhancement solution which contained mainly 2-naphthoyltrifluoroacetone. 25μl of Calibrators or samples and 200 μl of the assay buffer were pipetted into coated microtiter wells. The plates were incubated with mechanical shaking for 1 h at 25 degree C, washed two times, then added 100 μl Eu3+- McAb solution diluted 50-fold in assay buffer. The plates were incubated again with mechanical shaking for 1 h at 25 degree C,After six washings, 200 μl of enhancement solution were dispense into each well. The plates were shaken for 5 min and fluorescence readings. All the proceeding were done by auto DELFIA1235, software was designed by our lab. The calibration curve and calculation of the concentrations in the unknown samples were performed automatically by using Multicalc software program, where a spline algorithm on logarithmically transformed data was employed. Results: The average labelling yield is 8.6 Eu3+/McAb giving high sensitivity with low background(<1000 cps). The measurement range was 3.5-328 μ g /L with ED25, ED50, ED80 of 11.34 ±0.2 μ g/L, 38.73±0.8 μ g /L and 132,3±2.9 μ g/L. The detection limit, defined as the concentration of PGI corresponding to the fluorescence of the zero calibrators plus two SDs, is 0..05μg/L. Within-run and between-run precision was l.9% and 4.7% which assessed at various PGI concentrations between 5 and 300 μg/L. We checked for cross

  4. Application of microfluidic devices for time resolved FTIR spectroscopy

    International Nuclear Information System (INIS)

    Wagner, C.

    2012-01-01

    Within this thesis, micro fluidic mixers, operated in continuous flow mode, were used for time resolved FTIR studies of chemical reactions in aqueous solution. Any chemical reaction, that can be started upon mixing two reagents, can be examined with this technique. The mixing channel also serves as the observation window for the IR measurements. The actual measurements take place at well defined spots along this channel, corresponding to specific reaction times: moving the measurement spot (100 × 100 μm 2 ) towards the entry yields shorter reaction times, moving it towards the channel's end gives longer reaction times. The temporal resolution of the experiment depends on the flow rate inside the mixing channel and the spacing between subsequent measurement points. Fast flow rates, limited by the back pressure of the mixer leading to leakages, allow time resolutions in the sub-millisecond time range using a standard FTIR microscope, whereas slow flow rates allow the measurement of reaction times up to 1000 ms. Evaluating the mixer using a fast chemical reaction resulted in mixing times of approximately 5 ms and a homogeneous distribution of the liquids across the width of the mixing channel. The mixer was then used for the measurement of the H/D exchange on carbohydrates, the complex formaldehyde sulfite clock reaction, and the folding of the protein ubiquitin from its native to the ''A'' state, induced by mixing it with an acidified methanol solution. For cleaning the mixer a software tool, called ATLAS, was developed in LabVIEW, which was used to automatize the necessary cleaning steps performed by a dedicated flow system. Additionally, the micro mixer technology was combined with the step scan measurement technique using a beam condenser focusing the IR beam of an FTIR spectrometer down to a spot size of 1 mm diameter and through the mixer. The laser light, initiating the chemical reaction inside the mixing channel, was coupled into the focusing unit using a

  5. 20/30 GHz dual-band circularly polarized reflectarray antenna based on the concentric dual split-loop element

    DEFF Research Database (Denmark)

    Smith, Thomas Gunst; Vesterdal Larsen, Niels; Vesterager Gothelf, Ulrich

    2012-01-01

    A concentric dual split-loop element is designed and investigated for reflectarray antenna design in the emerging 20 GHz and 30 GHz Ka-band satellite communication spectrum. The element is capable of providing adjustment of the phase of reflection coefficients for circular plane waves in two...

  6. Solvent sorting in (mixed solvent electrolyte) systems: Time-resolved ...

    Indian Academy of Sciences (India)

    eral studies7–19 that investigated the solvation and rota- tional dynamics either in electrolyte solutions in a sin- gle polar solvent or in binary mixtures in the absence of any electrolyte, similar studies for electrolyte solutions. £For correspondence ..... vent rotation being much faster than the ion translation provides some ...

  7. Pulse radiolysis of alkanes: a time-resolved EPR study - Part I. Alkyl radicals

    International Nuclear Information System (INIS)

    Shkrob, I.A.; Trifunac, A.D.

    1995-01-01

    Time-resolved EPR was applied to detect short-lived alkyl radicals in pulse radiolysis of liquid alkanes. Two problems were addressed: (i) the mechanism of radical formation and (ii) the mechanism of chemically-induced spin polarization in these radicals. (i) The ratio of yields of penultimate and interior radicals in n-alkanes at the instant of their generation was found to be ≅ 1.25 times greater than the statistical quantity. This higher-than-statistical production of penultimate radicals indicates that the proton transfer reaction involving excited radical cations must be a prevailing route of radical generation. The relative yields of hydrogen abstraction and fragmentation for various branched alkanes are estimated. It is concluded that the fragmentation occurs prior to the formation of radicals in an excited precursor species. (ii) The analysis of spin-echo kinetics in n-alkanes suggests that the alkyl radicals gain the emissive polarization in spur reactions. This initial polarization increases with shortening of the aliphatic chain. We suggest that the origin of this polarization is the ST mechanism operating in the pairs of alkyl radicals and hydrogen atoms generated in dissociation of excited alkane molecules. It is also found that a long-chain structure of alkyl radicals results in much higher rate of Heisenberg spin exchange relative to the recombination rate (up to 30 times). That suggests prominent steric effects in recombination or the occurrence of through-chain electron exchange. The significance of these results in the context of cross-linking in polyethylene and higher paraffins is discussed. (Author)

  8. Prediction of aeroacoustic sound using the flow field obtained by time-resolved particle image velocimetry

    International Nuclear Information System (INIS)

    Uda, T; Nishikawa, A; Someya, S; Iida, A

    2011-01-01

    Based on vortex theory, we experimentally and directly predict sound sources distributing in the flow field and determine the sound pressure level as a result of the spatial integration of sound sources. In employing this direct evaluation method for the aeroacoustic sound, the problem is that a large integration area is required to minimize errors caused by the sudden truncation of the integration area; we overcome it by adopting and applying a modified formula that neglects the quadrupole sound under the condition that the dipole sound is dominant at a low Mach number. Through the flow field measurement using a time-resolved particle image velocimetry (TR-PIV) technique, we will clearly demonstrate the feasibility of our method and the distribution of dipole sound sources in the vicinity of a body even if a comparatively small integration area must be taken. In this basic study, a circular cylinder with a diameter of 6.0 mm is used; the spatially integrated sound pressure is compared with the actual sound pressure which is measured with a microphone. Further, the sound sources evaluated using only the flow field are determined, which give us detailed information about the amplitude and phase of the sound source structure. This direct evaluation method for the dipole sound is applicable to a more complex body

  9. Time-resolved and mechanistic study of the photochemical uncaging reaction of the o-hydroxycinnamic caged compound.

    Science.gov (United States)

    Yu, Youqing; Wu, Lidan; Zou, Xiaoran; Dai, Xiaojuan; Liu, Kunhui; Su, Hongmei

    2013-08-22

    The o-hydroxycinnamic derivatives represent efficient caged compounds that can realize quantification of delivery upon uncaging, but there has been lack of time-resolved and mechanistic studies. We used time-resolved infrared (TRIR) spectroscopy to investigate the photochemical uncaging dynamics of the prototype o-hydroxycinnamic compound, (E)-3-(2-hydroxyphenyl)-acrylic acid ethyl ester (HAAEE), leading to coumarin and ethanol upon uncaging. Taking advantage of the specific vibrational marker bands and the IR discerning capability, we have identified and distinguished two key intermediate species, the cis-isomers of HAAEE and the tetrahedral intermediate, in the transient infrared spectra, thus providing clear spectral evidence to support the intramolecular nucleophilic addition mechanism following the trans-cis photoisomerization. Moreover, the product yields of coumarin upon uncaging were observed to be greatly affected by the solvent polarity, suppressed in CH2Cl2 but enhanced in D2O/CH3CN with the increasing volume ratio of D2O. The highly solvent-dependent behavior indicates E1 elimination of the tetrahedral intermediate to give rise to the final uncaging product coumarin. The photorelease rate of coumarin was directly characterized from TRIR (3.6 × 10(6) s(-1)), revealing the promising application of such o-hydroxycinnamic compound in producing fast alcohol jumps. The TRIR results provide the first time-resolved detection and thus offer direct dynamical information about this photochemical uncaging reaction.

  10. Absolute calibration of space- and time-resolving flat-field vacuum ultraviolet spectrograph for plasma diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Okamoto, Yuuji; Yoshikawa, Masayuki; Watabe, Chikara; Tamano, Teruo; Kawamori, Eiichirou; Ito, Takahiro; Watanabe, Yoshihiko; Yatsu, Kiyoshi [Plasma Research Center, Tsukuba Univ., Ibaraki (Japan); Yamaguchi, Naohiro [Toyota Technological Inst., Nagoya (Japan)

    2000-06-01

    Measurement of spectra in the wavelength range from vacuum ultraviolet (VUV) to soft X-ray is an important means to diagnose impurities in magnetically confined plasmas used in fusion plasmas such as a GAMMA10 plasma. Recently, a space- and time-resolving flat-field grazing-incidence VUV spectrograph was constructed for the simultaneous observation of spatial, temporal and spectral distributions of plasma radiation in the wavelength range of 150-1050 A. Absolute calibration experiments were performed at beamline 11C in the Photon Factory at the High Energy Accelerator Research Organization. The absolute efficiency of the VUV spectrograph was measured for P polarization geometry in the spectrograph. (author)

  11. Absolute calibration of space- and time-resolving flat-field vacuum ultraviolet spectrograph for plasma diagnostics

    International Nuclear Information System (INIS)

    Okamoto, Yuuji; Yoshikawa, Masayuki; Watabe, Chikara; Tamano, Teruo; Kawamori, Eiichirou; Ito, Takahiro; Watanabe, Yoshihiko; Yatsu, Kiyoshi; Yamaguchi, Naohiro

    2000-01-01

    Measurement of spectra in the wavelength range from vacuum ultraviolet (VUV) to soft X-ray is an important means to diagnose impurities in magnetically confined plasmas used in fusion plasmas such as a GAMMA10 plasma. Recently, a space- and time-resolving flat-field grazing-incidence VUV spectrograph was constructed for the simultaneous observation of spatial, temporal and spectral distributions of plasma radiation in the wavelength range of 150-1050 A. Absolute calibration experiments were performed at beamline 11C in the Photon Factory at the High Energy Accelerator Research Organization. The absolute efficiency of the VUV spectrograph was measured for P polarization geometry in the spectrograph. (author)

  12. Three-Way-Switchable (Right/Left/OFF) Selective Reflection of Circularly Polarized Light on Solid Thin Films of Helical Polymer Blends.

    Science.gov (United States)

    Nagata, Yuuya; Uno, Makoto; Suginome, Michinori

    2016-06-13

    Two poly(quinoxaline-2,3-diyl) copolymers bearing miscibility-enhancing 8-chlorooctyloxy and (S)-2-methylbutoxy or n-butoxy side chains were synthesized. After annealing in CHCl3 vapor, a polymer-blend film of these copolymers exhibited selective reflection of right-handed circularly polarized light (CPL) in the visible region. The handedness of the CPL reflected was completely inverted upon annealing of the film in THF vapor. Annealing in n-hexane vapor resulted in the phase separation of the polymer blend, which turned the selective reflection off. This three-way-switchable reflection, that is, reflection of right-handed or left-handed CPL, together with an OFF state, could be observed visually through right- and left-handed CPL filters. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Effect of a radial space-charge field on the movement of particles in a magneto-static field and under the influence of a circularly polarized wave

    International Nuclear Information System (INIS)

    Buffa, A.

    1967-06-01

    The effect of a circularly polarized wave on a cylindrical plasma in a axial magnetostatic field and a radial space-charge field proportional to r is studied. Single particle motion is considered. The electrostatic field produces a shift in the cyclotron resonance frequency and,in case of high charge density, a radial movement of the off-resonance particles. In these conditions a radio-frequency-particle resonance is also possible called 'drift-resonance'. The drift resonance can be produced, with whistler mode, and may be employed in ion acceleration. Afterwards parametrical resonances produced by space-charge field oscillations and collisional limits of theory are studied. Cases in which ion acceleration is possible are considered on the basis of a quantitative analysis of results. (author) [fr

  14. Propagation properties of right-hand circularly polarized Airy-Gaussian beams through slabs of right-handed materials and left-handed materials.

    Science.gov (United States)

    Huang, Jiayao; Liang, Zijie; Deng, Fu; Yu, Weihao; Zhao, Ruihuang; Chen, Bo; Yang, Xiangbo; Deng, Dongmei

    2015-11-01

    The propagation of right-hand circularly polarized Airy-Gaussian beams (RHCPAiGBs) through slabs of right-handed materials (RHMs) and left-handed materials (LHMs) is investigated analytically and numerically with the transfer matrix method. An approximate analytical expression for the RHCPAiGBs passing through a paraxial ABCD optical system is derived on the basis of the Huygens diffraction integral formula. The intensity and the phase distributions of the RHCPAiGBs through RHMs and LHMs are demonstrated. The influence of the parameter χ0 on the propagation of RHCPAiGBs through RHM and LHM slabs is investigated. The RHCPAiGBs possess transverse-momentum currents, which shows that the physics underlying this intriguing accelerating effect is that of the combined contributions of the transverse spin and transverse orbital currents. Additionally, we go a step further to explore the radiation force including the gradient force and scattering force of the RHCPAiGBs.

  15. Electron's anomalous magnetic-moment effects on electron-hydrogen elastic collisions in the presence of a circularly polarized laser field

    International Nuclear Information System (INIS)

    Elhandi, S.; Taj, S.; Attaourti, Y.; Manaut, B.; Oufni, L.

    2010-01-01

    The effect of the electron's anomalous magnetic moment on the relativistic electronic dressing for the process of electron-hydrogen atom elastic collisions is investigated. We consider a laser field with circular polarization and various electric field strengths. The Dirac-Volkov states taking into account this anomaly are used to describe the process in the first order of perturbation theory. The correlation between the terms coming from this anomaly and the electric field strength gives rise to the strong dependence of the spinor part of the differential cross section (DCS) with respect to these terms. A detailed study has been devoted to the nonrelativistic regime as well as the moderate relativistic regime. Some aspects of this dependence as well as the dynamical behavior of the DCS in the relativistic regime have been addressed.

  16. Ultrashort x-ray pulse generation by nonlinear Thomson scattering of a relativistic electron with an intense circularly polarized laser pulse

    Directory of Open Access Journals (Sweden)

    F. Liu

    2012-07-01

    Full Text Available The nonlinear Thomson scattering of a relativistic electron with an intense laser pulse is calculated numerically. The results show that an ultrashort x-ray pulse can be generated by an electron with an initial energy of 5 MeV propagating across a circularly polarized laser pulse with a duration of 8 femtosecond and an intensity of about 1.1×10^{21}  W/cm^{2}, when the detection direction is perpendicular to the propagation directions of both the electron and the laser beam. The optimal values of the carrier-envelop phase and the intensity of the laser pulse for the generation of a single ultrashort x-ray pulse are obtained and verified by our calculations of the radiation characteristics.

  17. A New Approach to Suppress the Effect of Machining Error for Waveguide Septum Circular Polarizer at 230 GHz Band in Radio Astronomy

    Science.gov (United States)

    Hasegawa, Yutaka; Harada, Ryohei; Tokuda, Kazuki; Kimura, Kimihiro; Ogawa, Hideo; Onishi, Toshikazu; Nishimura, Atsushi; Han, Johnson; Inoue, Makoto

    2017-05-01

    A new stepped septum-type waveguide circular polarizer (SST-CP) was developed to operate in the 230 GHz band for radio astronomy, especially submillimeter-band VLBI observations. For previously reported SST-CP models, the 230 GHz band is too high to achieve the design characteristics in manufactured devices because of unexpected machining errors. To realize a functional SST-CP that can operate in the submillimeter band, a new method was developed, in which the division surface is shifted from the top step of the septum to the second step from the top, and we simulated the expected machining error. The SST-CP using this method can compensate for specified machining errors and suppress serious deterioration. To verify the proposed method, several test pieces were manufactured, and their characteristics were measured using a VNA. These results indicated that the insertion losses were approximately 0.75 dB, and the input return losses and the crosstalk of the left- and right-hand circular polarization were greater than 20 dB at 220-245 GHz on 300 K. Moreover, a 230 GHz SST-CP was developed by the proposed method and installed in a 1.85-m radio telescope receiver systems, and then had used for scientific observations during one observation season without any problems. These achievements demonstrate the successful development of a 230 GHz SST-CP for radio astronomical observations. Furthermore, the proposed method can be applicable for observations in higher frequency bands, such as 345 GHz.

  18. Administrative Circulars

    CERN Multimedia

    Département des Ressources humaines

    2004-01-01

    Administrative Circular N° 2 (Rev. 2) - May 2004 Guidelines and procedures concerning recruitment and probation period of staff members This circular has been revised. It cancels and replaces Administrative Circular N° 2 (Rev. 1) - March 2000. Administrative Circular N° 9 (Rev. 3) - May 2004 Staff members contracts This circular has been revised. It cancels and replaces Administrative Circular N° 9 (Rev. 2) - March 2000. Administrative Circular N° 26 (Rev. 4) - May 2004 Procedure governing the career evolution of staff members This circular has also been revised. It Administrative Circulars Administrative Circular N° 26 (Rev. 3) - December 2001 and brings up to date the French version (Rev. 4) published on the HR Department Web site in January 2004. Operational Circular N° 7 - May 2004 Work from home This circular has been drawn up. Operational Circular N° 8 - May 2004 Dealing with alcohol-related problems...

  19. Stationary and time-resolved spectra analysis of pyrazoloquinoline derivatives with pyridyl moiety

    Science.gov (United States)

    Grabka, Danuta; Kolbus, Anna; Danel, Andrzej; Kucharek, Mateusz; Szary, Karol

    2018-03-01

    Two derivatives of pyrazoloquinoline with pyridyl moiety: 6-N,N-dimethyl-3-phenyl-1-(2-pyridyl)-1H-pyrazolo[3,4-b]quinoline (DMA-1PPhPQ) and 6-N,N-dimethyl-1,3-(di-2-pyridyl)-1H-pyrazolo[3,4-b]quinoline (DMA-1,3PPQ) were synthesized with commercial substrates. The theoretical characterization of both compounds was done. Geometry optimizations give not flat structure with the first absorption band at the wavelength about 390 nm for both compounds. Several electro-optical parameters were also calculated. The optical properties of DMA-1PPHPQ and DMA-1,3PPQ were investigated by ultraviolet-visible spectroscopy and stationary as well as time-resolved fluorescence. The fluorescence maximum and fluorescence quantum yield are strongly dependent on solvent polarity function. Results indicate CT fluorescence for both compounds. Because of high emission the investigated pyrazoloquinoline derivatives can be potential candidates for fabrications of electroluminescent devices.

  20. Femtosecond time-resolved studies of coherent vibrational Raman scattering in large gas-phase molecules

    International Nuclear Information System (INIS)

    Hayden, C.C.; Chandler, D.W.

    1995-01-01

    Results are presented from femtosecond time-resolved coherent Raman experiments in which we excite and monitor vibrational coherence in gas-phase samples of benzene and 1,3,5-hexatriene. Different physical mechanisms for coherence decay are seen in these two molecules. In benzene, where the Raman polarizability is largely isotropic, the Q branch of the vibrational Raman spectrum is the primary feature excited. Molecules in different rotational states have different Q-branch transition frequencies due to vibration--rotation interaction. Thus, the macroscopic polarization that is observed in these experiments decays because it has many frequency components from molecules in different rotational states, and these frequency components go out of phase with each other. In 1,3,5-hexatriene, the Raman excitation produces molecules in a coherent superposition of rotational states, through (O, P, R, and S branch) transitions that are strong due to the large anisotropy of the Raman polarizability. The coherent superposition of rotational states corresponds to initially spatially oriented, vibrationally excited, molecules that are freely rotating. The rotation of molecules away from the initial orientation is primarily responsible for the coherence decay in this case. These experiments produce large (∼10% efficiency) Raman shifted signals with modest excitation pulse energies (10 μJ) demonstrating the feasibility of this approach for a variety of gas phase studies. copyright 1995 American Institute of Physics

  1. Difference between the Brewster angle and angle of minimum reflectance for incident unpolarized or circularly polarized light at interfaces between transparent media.

    Science.gov (United States)

    Azzam, R M A

    2015-06-01

    For reflection at interfaces between transparent optically isotropic media, the difference between the Brewster angle ϕB of zero reflectance for incident p-polarized light and the angle ϕu min of minimum reflectance for incident unpolarized or circularly polarized light is considered as function of the relative refractive n in external and internal reflection. We determine the following. (i) ϕu min reflection (n > 1), the maximum difference (ϕB - ϕu min)max = 75° at n = 2 + √3. (iii) In internal reflection and 0 reflectance R0 at normal incidence is in the range 0 ≤ R0 ≤ 1/3, ϕu min = 0, and ϕB - ϕu min = ϕB. (v) For internal reflection and 0 < n < 2 - √3, ϕu min exhibits an unexpected maximum (= 12.30°) at n = 0.24265. Finally, (vi) for 1/3 ≤ R0 < 1, Ru min at ϕu min is limited to the range 1/3 ≤ Ru min < 1/2.

  2. Indoor radio channel modeling and mitigation of fading effects using linear and circular polarized antennas in combination for smart home system at 868 MHz

    Science.gov (United States)

    Wunderlich, S.; Welpot, M.; Gaspard, I.

    2014-11-01

    The markets for smart home products and services are expected to grow over the next years, driven by the increasing demands of homeowners considering energy monitoring, management, environmental controls and security. Many of these new systems will be installed in existing homes and offices and therefore using radio based systems for cost reduction. A drawback of radio based systems in indoor environments are fading effects which lead to a high variance of the received signal strength and thereby to a difficult predictability of the encountered path loss of the various communication links. For that reason it is necessary to derive a statistical path loss model which can be used to plan a reliable and cost effective radio network. This paper presents the results of a measurement campaign, which was performed in six buildings to deduce realistic radio channel models for a high variety of indoor radio propagation scenarios in the short range devices (SRD) band at 868 MHz. Furthermore, a potential concept to reduce the variance of the received signal strength using a circular polarized (CP) patch antenna in combination with a linear polarized antenna in an one-to-one communication link is presented.

  3. Time-resolved detection of surface plasmon polaritons with a scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, T.; Jensen, Jacob Riis

    1998-01-01

    We present the time-resolved detection of surface plasmon polaritons with an STM. The results indicate that the time resolved signal is due to rectification of coherently superimposed plasmon voltages. The comparison with differential reflectivity measurements shows that the tip itself influences...

  4. A Low-Cost Time-Resolved Spectrometer for the Study of Ruby Emission

    Science.gov (United States)

    McBane, George C.; Cannella, Christian; Schaertel, Stephanie

    2018-01-01

    A low-cost time-resolved emission spectrometer optimized for ruby emission is presented. The use of a Class II diode laser module as the excitation source reduces costs and hazards. The design presented here can facilitate the inclusion of time-resolved emission spectroscopy with laser excitation sources in the undergraduate laboratory curriculum.…

  5. Circular differential microscopy

    International Nuclear Information System (INIS)

    Maestre, M.F.; Bustamante, C.; Keller, D.

    1985-01-01

    The authors describe the historical development of the theory of differential imaging and the invention of the circular differential imaging microscope. The technique is shown to be a logical extension of the research on the interaction of circularly polarized light with stuctures whose dimensions are arbitrary with respect to the wavelength of light. Shown is the circular dichroism spectra in arbitrary units of E. cirrhosa sperm heads, measured by techniques with different collection angles of scattered light. Also presented is a scanning electron micrograph of a freexe-dried sperm head from E. cirrhosa. It was shown that circular differential scattering is specially sensitive to the dimensions of the structure close to the wavelength of the incident light, and application of circular intensity differential scattering theory to images extend these results

  6. Investigation and Characterization of Defects in Epitaxial Films for Ultraviolet Light Emitting Devices Using FUV Time-Resolved Photoluminescence, Time-Resolved Cathodoluminescence, and Spatio-Time-Resolved Cathodoluminescence Excited Using Femtosecond Laser Pulses

    Science.gov (United States)

    2013-05-22

    STRCL system. Introduction: Aluminium nitride (AlN) and high AlN mole fraction AlxGa1-xN alloys have attracted considerable interest for...resolution of approximately 10 ps. (7) STRCL studies on local exciton dynamics of a freestanding GaN substrate grown by hydride vapor phase...Namita, S. Nagao, K. Fujito, and A. Uedono, "Spatio-time-resolved cathodoluminescence studies on freestanding GaN substrates grown by hydride vapor

  7. Quasi-analytical synthesis of continuous phase correcting structures to increase the directivity of circularly polarized Fabry-Perot resonator antennas

    International Nuclear Information System (INIS)

    Afzal, Muhammad U.; Esselle, Karu P.

    2015-01-01

    This paper presents a quasi-analytical technique to design a continuous, all-dielectric phase correcting structures (PCSs) for circularly polarized Fabry-Perot resonator antennas (FPRAs). The PCS has been realized by varying the thickness of a rotationally symmetric dielectric block placed above the antenna. A global analytical expression is derived for the PCS thickness profile, which is required to achieve nearly uniform phase distribution at the output of the PCS, despite the non-uniform phase distribution at its input. An alternative piecewise technique based on spline interpolation is also explored to design a PCS. It is shown from both far- and near-field results that a PCS tremendously improves the radiation performance of the FPRA. These improvements include an increase in peak directivity from 22 to 120 (from 13.4 dBic to 20.8 dBic) and a decrease of 3 dB beamwidth from 41.5° to 15°. The phase-corrected antenna also has a good directivity bandwidth of 1.3 GHz, which is 11% of the center frequency

  8. The third post-Newtonian gravitational wave polarizations and associated spherical harmonic modes for inspiralling compact binaries in quasi-circular orbits

    International Nuclear Information System (INIS)

    Blanchet, Luc; Faye, Guillaume; Iyer, Bala R; Sinha, Siddhartha

    2008-01-01

    The gravitational waveform (GWF) generated by inspiralling compact binaries moving in quasi-circular orbits is computed at the third post-Newtonian (3PN) approximation to general relativity. Our motivation is two-fold: (i) to provide accurate templates for the data analysis of gravitational wave inspiral signals in laser interferometric detectors; (ii) to provide the associated spin-weighted spherical harmonic decomposition to facilitate comparison and match of the high post-Newtonian prediction for the inspiral waveform to the numerically-generated waveforms for the merger and ringdown. This extension of the GWF by half a PN order (with respect to previous work at 2.5PN order) is based on the algorithm of the multipolar post-Minkowskian formalism, and mandates the computation of the relations between the radiative, canonical and source multipole moments for general sources at 3PN order. We also obtain the 3PN extension of the source multipole moments in the case of compact binaries, and compute the contributions of hereditary terms (tails, tails-of-tails and memory integrals) up to 3PN order. The end results are given for both the complete plus and cross polarizations and the separate spin-weighted spherical harmonic modes

  9. Lethality in mice and rats exposed to 2450 MHz circularly polarized microwaves as a function of exposure duration and environmental factors

    Energy Technology Data Exchange (ETDEWEB)

    Berman, E.; Kinn, J.B.; Ali, J.; Carter, H.B.; Rehnberg, B.; Stead, A.G.

    1985-02-01

    Adult male CD-1 mice and CD rats were used to determine LD50/24 h lethality rates from exposure to 2450-MHz circularly polarized microwaves. Groups of 16 mice or six rats were exposed in each of 32 combinations of nominal power density, exposure duration, and environmental temperature and relative humidity. An analysis of variance probit model was used to determine the influence each variable had on the probability of death. Significant factors in lethality were nominal power density, exposure duration and environmental temperature, but not environmental relative humidity. The estimated power density (mW cm-2) required to kill 50% of the animals in 24 h is halved when the environmental temperature is increased from 20 to 30 degrees C. Similarly, only 20-25% of the power density is required when the exposure duration is increased from 1 to 4 h. The use of nominal power density as a predictor of the probability of death was more efficient than specific absorption rate estimated experimentally by twin-well calorimetry. The exposure of one mouse at a time, instead of 16, did not alter the predicted death rate.

  10. ANN Synthesis Model of Single-Feed Corner-Truncated Circularly Polarized Microstrip Antenna with an Air Gap for Wideband Applications

    Directory of Open Access Journals (Sweden)

    Zhongbao Wang

    2014-01-01

    Full Text Available A computer-aided design model based on the artificial neural network (ANN is proposed to directly obtain patch physical dimensions of the single-feed corner-truncated circularly polarized microstrip antenna (CPMA with an air gap for wideband applications. To take account of the effect of the air gap, an equivalent relative permittivity is introduced and adopted to calculate the resonant frequency and Q-factor of square microstrip antennas for obtaining the training data sets. ANN architectures using multilayered perceptrons (MLPs and radial basis function networks (RBFNs are compared. Also, six learning algorithms are used to train the MLPs for comparison. It is found that MLPs trained with the Levenberg-Marquardt (LM algorithm are better than RBFNs for the synthesis of the CPMA. An accurate model is achieved by using an MLP with three hidden layers. The model is validated by the electromagnetic simulation and measurements. It is enormously useful to antenna engineers for facilitating the design of the single-feed CPMA with an air gap.

  11. Compton polarimetry detection of small circularly and linearly polarized impurities in Mössbauer 8.4 keV (3/2-1/2) M1 γ-transition of {sup 169}Tm

    Energy Technology Data Exchange (ETDEWEB)

    Tsinoev, V.; Cherepanov, V.; Shuvalov, V.; Balysh, A.; Gabbasov, R., E-mail: graul@list.ru [National Research Centre “Kurchatov Institute” (Russian Federation)

    2016-12-15

    The arrangement of an experiment to detect the P−odd and P, T−odd polarized part of the Mössbauer ({sup +}3/2– {sup +}1/2) gamma transition of a deformed {sup 169}Tm nucleus with an energy of 8.4 keV by Compton polarimetry is discussed. Tm {sub 2}O{sub 3} single crystal with a quadrupolarly split Mössbauer spectrum is proposed as a resonance polarizer. A Be-scatterer-based Compton polarimeter and a synchronously detecting system will be used to measure the P-odd circular polarization P{sub C}and P, T-odd linear polarization P{sub L}.The expected accuracy of measuring the relative magnitude of the P, T-odd contribution is about 1% of the magnitude of usual weak nucleon–nucleon interaction.

  12. A flexible experimental setup for femtosecond time-resolved broad-band ellipsometry and magneto-optics

    Energy Technology Data Exchange (ETDEWEB)

    Boschini, F.; Hedayat, H.; Piovera, C.; Dallera, C. [Dipartimento di Fisica, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milano (Italy); Gupta, A. [Department of Chemistry, University of Alabama, Tuscaloosa, Alabama 35487 (United States); Carpene, E., E-mail: ettore.carpene@polimi.it [CNR-IFN, Dipartimento di Fisica, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milano (Italy)

    2015-01-15

    A versatile experimental setup for femtosecond time-resolved ellipsometry and magneto-optical Kerr effect measurements in the visible light range is described. The apparatus is based on the pump-probe technique and combines a broad-band probing beam with an intense near-infrared pump. According to Fresnel scattering matrix formalism, the analysis of the reflected beam at different polarization states of the incident probe light allows one to determine the diagonal and the off-diagonal elements of the dielectric tensor in the investigated sample. Moreover, the pump-probe method permits to study the dynamics of the dielectric response after a short and intense optical excitation. The performance of the experimental apparatus is tested on CrO{sub 2} single crystals as a benchmark.

  13. High time resolved electron temperature measurements by using the multi-pass Thomson scattering system in GAMMA 10/PDX

    Science.gov (United States)

    Yoshikawa, Masayuki; Yasuhara, Ryo; Ohta, Koichi; Chikatsu, Masayuki; Shima, Yoriko; Kohagura, Junko; Sakamoto, Mizuki; Nakashima, Yousuke; Imai, Tsuyoshi; Ichimura, Makoto; Yamada, Ichihiro; Funaba, Hisamichi; Minami, Takashi

    2016-11-01

    High time resolved electron temperature measurements are useful for fluctuation study. A multi-pass Thomson scattering (MPTS) system is proposed for the improvement of both increasing the TS signal intensity and time resolution. The MPTS system in GAMMA 10/PDX has been constructed for enhancing the Thomson scattered signals for the improvement of measurement accuracy. The MPTS system has a polarization-based configuration with an image relaying system. We optimized the image relaying optics for improving the multi-pass laser confinement and obtaining the stable MPTS signals over ten passing TS signals. The integrated MPTS signals increased about five times larger than that in the single pass system. Finally, time dependent electron temperatures were obtained in MHz sampling.

  14. Time-resolved spectroscopy of excitons and carriers in GaN and InGaN

    International Nuclear Information System (INIS)

    Kyhm, K.

    2001-01-01

    The emission mechanisms in GaN and ln x Ga 1-x N is systematically studied to investigate carrier and exciton dynamics. Reflectance, time-integrated luminescence, and time-resolved reflectance spectroscopy are used to study exciton transitions in GaN, and the saturation of the exciton resonances with increasing carrier density has been measured in the case of resonant and non-resonant excitations. The coincidence between the density for the onset of the stimulated emission and the Mott density leads us to the conclusion that the stimulated emission mechanism in GaN is due to the electron-hole plasma. A detailed study of hot carrier relaxation at low temperature is presented, using pump-probe transmission spectroscopy. At early times, phonon satellites are seen, and a strong non-thermal electron distribution in the region of the LO-phonon energy arising from the remarkably strong electron-LO phonon interaction are observed. A measure of the mean energy of the carriers in non-thermal states agree well with our Monte-Carlo model, and confirms the dominance of hot phonon effect at early times. Time-resolved photoluminescence measurements are performed in a In 0.02 Ga 0.98 N/In 0.16 Ga 0.84 N multiple quantum well structure to investigate the spontaneous recombination mechanism. The gain spectrum for the different stripe lengths using the VSLM technique suggests that nearly delocalised electron-hole pairs from the lowest confined level are responsible for the gain in our sample. The polarization dependence of biexcitonic signals and quantum beats between A-excitons (X A ) and A-biexcitons (X A X A ) in a high-quality GaN epilayer are measured by spectrally-resolved and time-integrated four-wave mixing measurements. We also measured the polarization dependent B-biexciton (X B X B ) signal. (author)

  15. Enantiomeric excesses induced in amino acids by ultraviolet circularly polarized light irradiation of extraterrestrial ice analogs: A possible source of asymmetry for prebiotic chemistry

    International Nuclear Information System (INIS)

    Modica, Paola; De Marcellus, Pierre; D'Hendecourt, Louis Le Sergeant; Meinert, Cornelia; Meierhenrich, Uwe J.; Nahon, Laurent

    2014-01-01

    The discovery of meteoritic amino acids with enantiomeric excesses of the L-form (ee L ) has suggested that extraterrestrial organic materials may have contributed to prebiotic chemistry and directed the initial occurrence of the ee L that further led to homochirality of amino acids on Earth. A proposed mechanism for the origin of ee L in meteorites involves an asymmetric photochemistry of extraterrestrial ices by UV circularly polarized light (CPL). We have performed the asymmetric synthesis of amino acids on achiral extraterrestrial ice analogs by VUV CPL, investigating the chiral asymmetry transfer at two different evolutionary stages at which the analogs were irradiated (regular ices and/or organic residues) and at two different photon energies (6.6 and 10.2 eV). We identify 16 distinct amino acids and precisely measure the L-enantiomeric excesses using the enantioselective GC × GC-TOFMS technique in five of them: α-alanine, 2,3-diaminopropionic acid, 2-aminobutyric acid, valine, and norvaline, with values ranging from ee L = –0.20% ± 0.14% to ee L = –2.54% ± 0.28%. The sign of the induced ee L depends on the helicity and the energy of CPL, but not on the evolutionary stage of the samples, and is the same for all five considered amino acids. Our results support an astrophysical scenario in which the solar system was formed in a high-mass star-forming region where icy grains were irradiated during the protoplanetary phase by an external source of CPL of a given helicity and a dominant energy, inducing a stereo-specific photochemistry.

  16. Ultrafast time-resolved spectroscopy of the spin-Peierls compound CuGeO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, Y. [Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581 (Japan)], E-mail: yuasa@issp.u-tokyo.ac.jp; Nakajima, M.; Yamanouchi, T.; Ueda, Y.; Suemoto, T. [Institute for Solid State Physics, University of Tokyo, Kashiwanoha 5-1-5, Kashiwa, Chiba 277-8581 (Japan)

    2008-05-15

    Coherent phonons and electronic response of the spin-Peierls compound CuGeO{sub 3} are investigated at room temperature using time-resolved transmission measurement. Four A{sub g} modes are observed strongly in the E-parallel b polarization, consistent with the Raman spectra. Coherent lattice oscillation with the highest frequency of 860 cm{sup -1} is kicked on with an initial phase of -(0.5{+-}0.2){pi} radian and decays with a time constant of about 0.9 ps, indicating the ground-state phonon is induced by the process of impulsive stimulated Raman scattering (ISRS). The decay-time constants are rather long compared to the values expected from the line width of the stationary Raman spectrum. In addition, instantaneous photo-induced absorption is observed in the E-parallel b polarization at delay-time zero, whose temporal width is close to that of the cross-correlation between pump and probe, attributed to the two-photon absorption of the pump and the probe photons. The intensity of the negative peak-like response at delay-time zero increases in the E-parallel c polarization, and is ascribed to a cascade excitation via the Zhang-Rice (ZR)-like exciton. This absorption decays rapidly within 100 fs, indicating that the ZR excitons experience extremely fast relaxation after photoexcitation.

  17. Time-resolved resonance Raman spectroscopy of radiation-chemical processes

    International Nuclear Information System (INIS)

    Tripathi, G.N.R.

    1983-01-01

    A tunable pulsed laser Raman spectrometer for time resolved Raman studies of radiation-chemical processes is described. This apparatus utilizes the state of art optical multichannel detection and analysis techniques for data acquisition and electron pulse radiolysis for initiating the reactions. By using this technique the resonance Raman spectra of intermediates with absorption spectra in the 248-900 nm region, and mean lifetimes > 30 ns can be examined. This apparatus can be used to time resolve the vibrational spectral overlap between transients absorbing in the same region, and to follow their decay kinetics by monitoring the well resolved Raman peaks. For kinetic measurements at millisecond time scale, the Raman technique is preferable over optical absorption method where low frequency noise is quite bothersome. A time resolved Raman study of the pulse radiolytic oxidation of aqueous tetrafluorohydroquinone and p-methoxyphenol is briefly discussed. 15 references, 5 figures

  18. Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Tomita, Ayana; Chollet, Matthieu; Ichikawa, Hirohiko; Fujii, Hiroshi; Adachi, Shin-ichi; Koshihara, Shin-ya

    2009-01-01

    An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. The X-ray positional active feedback to crystals in a monochromator combined with a figure-of-merit scan of the laser beam position has been utilized as an essential tool to stabilize the spatial overlap of the X-ray and laser beams at the sample position. As a typical example, a time-resolved XAFS measurement of a photo-induced spin crossover reaction of the tris(1,10-phenanthrorine)iron(II) complex in water is presented

  19. Spatially resolved and time-resolved imaging of transport of indirect excitons in high magnetic fields

    Science.gov (United States)

    Dorow, C. J.; Hasling, M. W.; Calman, E. V.; Butov, L. V.; Wilkes, J.; Campman, K. L.; Gossard, A. C.

    2017-06-01

    We present the direct measurements of magnetoexciton transport. Excitons give the opportunity to realize the high magnetic-field regime for composite bosons with magnetic fields of a few tesla. Long lifetimes of indirect excitons allow the study of kinetics of magnetoexciton transport with time-resolved optical imaging of exciton photoluminescence. We performed spatially, spectrally, and time-resolved optical imaging of transport of indirect excitons in high magnetic fields. We observed that an increasing magnetic field slows down magnetoexciton transport. The time-resolved measurements of the magnetoexciton transport distance allowed for an experimental estimation of the magnetoexciton diffusion coefficient. An enhancement of the exciton photoluminescence energy at the laser excitation spot was found to anticorrelate with the exciton transport distance. A theoretical model of indirect magnetoexciton transport is presented and is in agreement with the experimental data.

  20. Time-resolved PHERMEX image restorations constrained with an additional multiply-exposed image

    International Nuclear Information System (INIS)

    Kruger, R.P.; Breedlove, J.R. Jr.; Trussell, H.J.

    1978-06-01

    There are a number of possible industrial and scientific applications of nanosecond cineradiographs. Although the technology exists to produce closely spaced pulses of x rays for this application, the quality of the time-resolved radiographs is severely limited. The limitations arise from the necessity of using a fluorescent screen to convert the transmitted x rays to light and then using electro-optical imaging systems to gate and to record the images with conventional high-speed cameras. It has been proposed that, in addition to the time-resolved images, a conventional multiply exposed radiograph be obtained. This report uses both PHERMEX and conventional photographic simulations to demonstrate that the additional information supplied by the multiply exposed radiograph can be used to improve the quality of digital image restorations of the time-resolved pictures over what could be achieved with the degraded images alone

  1. Time-resolved fluorescence and photon migration studies in biomedical and model random media

    International Nuclear Information System (INIS)

    Das, B.B.; Feng Liu; Alfano, R.R.

    1997-01-01

    This review highlights time-resolved fluorescence kinetics and photon transport in tissues and other biomedical media with a special emphasis on ultrafast measurements of key optical parameters. Measurements of fluorescence decay lifetimes from human breast and atherosclerotic artery tissues in the uv and visible region are described after a brief description of fundamentals of fluorescence kinetics. A time-dependent diffusion model for photon migration and various ultrafast methods for time-resolved light scattering measurements to obtain key optical parameters of tissues and other model turbid media are presented. The usefulness of optical parameters as markers in optical diagnostics and imaging is considered. Time-gated measurements of ballistic and snake photons to obtain shadowgrams and an inverse numerical reconstruction of the interior map of a turbid medium from time-resolved data in the context of optical tomography are presented. (author)

  2. Time-resolved materials science opportunities using synchrotron x-ray sources

    International Nuclear Information System (INIS)

    Larson, B.C.; Tischler, J.Z.

    1995-06-01

    The high brightness, high intensity, and pulsed time-structure of synchrotron sources provide new opportunities for time-resolved x-ray diffraction investigations. With third generation synchrotron sources coming on line, high brilliance and high brightness are now available in x-ray beams with the highest flux. In addition to the high average flux, the instantaneous flux available in synchrotron beams is greatly enhanced by the pulsed time structure, which consists of short bursts of x-rays that are separated by ∼tens to hundreds of nanoseconds. Time-resolved one- and two-dimensional position sensitive detection techniques that take advantage of synchrotron radiation for materials science x-ray diffraction investigations are presented, and time resolved materials science applications are discussed in terms of recent diffraction and spectroscopy results and materials research opportunities

  3. Femtosecond Time-Resolved Resonance-Enhanced CARS of Gaseous Iodine at Room Temperature

    Science.gov (United States)

    He, Ping; Fan, Rong-Wei; Xia, Yuan-Qin; Yu, Xin; Yao, Yong; Chen, De-Ying

    2011-04-01

    Time-resolved resonance-enhanced coherent anti-Stokes Raman scattering (CARS) is applied to investigate molecular dynamics in gaseous iodine. 40 fs laser pulses are applied to create and monitor the high vibrational states of iodine at room temperature (corresponding to a vapor pressure as low as about 35 Pa) by femtosecond time-resolved CARS. Depending on the time delay between the probe pulse and the pump/Stokes pulse pairs, the high vibrational states both on the electronically ground states and the excited states can be detected as oscillations in the CARS transient signal. It is proved that the femtosecond time-resolved CARS technique is a promising candidate for investigating the molecular dynamics of a low concentration system and can be applied to environmental and atmospheric monitoring measurements.

  4. Mobile charge generation dynamics in P3HT: PCBM observed by time-resolved terahertz spectroscopy

    DEFF Research Database (Denmark)

    Cooke, D. G.; Krebs, Frederik C; Jepsen, Peter Uhd

    2012-01-01

    Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale.......Ultra-broadband time-resolved terahertz spectroscopy is used to examine the sub-ps conductivity dynamics of a conjugated polymer bulk heterojunction film P3HT:PCBM. We directly observe mobile charge generation dynamics on a sub-100 fs time scale....

  5. Advances in high-order harmonic generation sources for time-resolved investigations

    Energy Technology Data Exchange (ETDEWEB)

    Reduzzi, Maurizio [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Carpeggiani, Paolo [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Kühn, Sergei [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Calegari, Francesca [Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Nisoli, Mauro; Stagira, Salvatore [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Vozzi, Caterina [Institute of Photonics and Nanotechnologies, CNR-IFN, Piazza Leonardo da Vinci 32, 20133 Milano (Italy); Dombi, Peter [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Wigner Research Center for Physics, 1121 Budapest (Hungary); Kahaly, Subhendu [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Tzallas, Paris; Charalambidis, Dimitris [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Foundation for Research and Technology – Hellas, Institute of Electronic Structure and Lasers, P.O. Box 1527, GR-711 10 Heraklion, Crete (Greece); Varju, Katalin [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); Department of Optics and Quantum Electronics, University of Szeged, Dóm tér 9, 6720 Szeged (Hungary); Osvay, Karoly [ELI-ALPS, ELI-Hu Kft., Dugonics ter 13, H-6720 Szeged (Hungary); and others

    2015-10-15

    We review the main research directions ongoing in the development of extreme ultraviolet sources based on high-harmonic generation for the synthesization and application of trains and isolated attosecond pulses to time-resolved spectroscopy. A few experimental and theoretical works will be discussed in connection to well-established attosecond techniques. In this context, we present the unique possibilities offered for time-resolved investigations on the attosecond timescale by the new Extreme Light Infrastructure Attosecond Light Pulse Source, which is currently under construction.

  6. Advances in high-order harmonic generation sources for time-resolved investigations

    International Nuclear Information System (INIS)

    Reduzzi, Maurizio; Carpeggiani, Paolo; Kühn, Sergei; Calegari, Francesca; Nisoli, Mauro; Stagira, Salvatore; Vozzi, Caterina; Dombi, Peter; Kahaly, Subhendu; Tzallas, Paris; Charalambidis, Dimitris; Varju, Katalin; Osvay, Karoly

    2015-01-01

    We review the main research directions ongoing in the development of extreme ultraviolet sources based on high-harmonic generation for the synthesization and application of trains and isolated attosecond pulses to time-resolved spectroscopy. A few experimental and theoretical works will be discussed in connection to well-established attosecond techniques. In this context, we present the unique possibilities offered for time-resolved investigations on the attosecond timescale by the new Extreme Light Infrastructure Attosecond Light Pulse Source, which is currently under construction.

  7. Time-resolved electron transport in quantum-dot systems; Zeitaufgeloester Elektronentransport in Quantendotsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Croy, Alexander

    2010-06-30

    In this thesis the time-resolved electron transport in quantum dot systems was studied. For this two different formalisms were presented: The nonequilibrium Green functions and the generalized quantum master equations. For both formalisms a propagation method for the numerical calculation of time-resolved expectation values, like the occupation and the electron current, was developed. For the demonstration of the propagation method two different question formulations were considered. On the one hand the stochastically driven resonant-level model was studied. On the other hand the pulse-induced transport through a double quantum dot was considered.

  8. Time-resolved imaging of purely valence-electron dynamics during a chemical reaction

    DEFF Research Database (Denmark)

    Hockett, Paul; Bisgaard, Christer Z.; Clarkin, Owen J.

    2011-01-01

    Chemical reactions are manifestations of the dynamics of molecular valence electrons and their couplings to atomic motions. Emerging methods in attosecond science can probe purely electronic dynamics in atomic and molecular systems(1-6). By contrast, time-resolved structural-dynamics methods......,17): in both cases, this sensitivity derives from the ionization-matrix element(18,19). Here we demonstrate a time-resolved molecular-frame photoelectron-angular-distribution (TRMFPAD) method for imaging the purely valence-electron dynamics during a chemical reaction. Specifically, the TRMFPADs measured during...

  9. Spin and time-resolved magnetic resonance in radiation chemistry. Recent developments and perspectives

    International Nuclear Information System (INIS)

    Shkrob, I.A.; Trifunac, A.D.

    1997-01-01

    Time-resolved pulsed EPR and ODMR in studies on early events in radiation chemistry are examined. It is concluded that these techniques yield valuable and diverse information about chemical reactions in spurs, despite the fact that the spur reactions occur on a time scale that is much shorter than the time resolution of these methods. Several recent examples include EPR of H/D atoms in vitreous silica and cryogenic liquids and ODMR of doped alkane solids and amorphous semiconductors. It is argued that a wider use of time-resolved magnetic resonance methods would benefit the studies on radiation chemistry of disordered solids, simple liquids, and polymers. (author)

  10. Direct probing of charge carrier behavior in multilayered organic light-emitting diode devices by time-resolved electric-field-induced sum-frequency generation spectroscopy

    Science.gov (United States)

    Miyamae, Takayuki; Takada, Noriyuki; Ohata, Hiroshi; Tsutsui, Tetsuo

    2017-10-01

    Time-resolved electric-field-induced sum-frequency generation (EFI-SFG) spectroscopy was employed to study the charge behavior of multilayer organic light-emitting diodes (OLEDs). Through application of the square wave pulse bias to the OLEDs, compensation for the polarization charges in the electron transport layer and the generation of 4,4‧-bis[N-(1-naphthyl-N-phenylamino)-biphenyl] (α-NPD) cations were observed. When the pulse voltage was turned off, the α-NPD cations immediately disappeared, confirming that charge recombination occurs at the interfaces. We therefore concluded that time-resolved EFI-SFG is useful for directly probing the carrier behavior in OLEDs in addition to identifying the origin of the charge carriers present in OLEDs.

  11. Information Circulars

    International Nuclear Information System (INIS)

    1969-01-01

    Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars which were of current interest on 15 January 1969 is given below, followed by an index to their subject matter. Other circulars can be traced by reference to earlier issues of the present document.

  12. Time Resolved Shadowgraph Images of Silicon during Laser Ablation: Shockwaves and Particle Generation

    International Nuclear Information System (INIS)

    Liu, C Y; Mao, X L; Greif, R; Russo, R E

    2007-01-01

    Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume

  13. Determination of the Diffusion Parameters of an Optically Thin Scattering Sample Through Time-resolved Transmission

    NARCIS (Netherlands)

    Aas, Mehdi; IJzerman, W.L.; Vissenberg, Gilles; Vos, Willem L.; Lagendijk, Ad

    2017-01-01

    The color-converting phosphor diffusers in white LEDs are optically thin and hence are hard to characterize. We show that separating of direct from diffuse transmission in time-resolved experiments results in less than 20% error in determining the diffusion parameters using the diffusion

  14. Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

    International Nuclear Information System (INIS)

    Kimura, Takaumi; Kato, Yoshiharu; Meinrath, G.; Yoshida, Zenko; Choppin, G.R.

    1995-01-01

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

  15. Time-resolved fluorescence analysis of the mobile flavin cofactor in ...

    Indian Academy of Sciences (India)

    TECS

    tron transfer; enzyme conformations; maximum entropy method. 1. Introduction ... 21,22. ) and. Tyr222 (hydrogen bonding. 4,5,23. ). The hydroxyl group of the substrate is at hydrogen-bonding distance of. Tyr201 and Tyr385. The latter residues have an .... In this contribution, time-resolved flavin fluore- scence studies are ...

  16. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

    International Nuclear Information System (INIS)

    Rutherford, Michael E.; Chapman, David J.; White, Thomas G.; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E.

    2016-01-01

    Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

  17. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources

    Energy Technology Data Exchange (ETDEWEB)

    Rutherford, Michael E.; Chapman, David J.; White, Thomas G. [Imperial College London, London (United Kingdom); Drakopoulos, Michael [Diamond Light Source, I12 Joint Engineering, Environmental, Processing (JEEP) Beamline, Didcot, Oxfordshire (United Kingdom); Rack, Alexander [European Synchrotron Radiation Facility, Grenoble (France); Eakins, Daniel E., E-mail: d.eakins@imperial.ac.uk [Imperial College London, London (United Kingdom)

    2016-03-24

    Scintillator performance in time-resolved, hard, indirect detection X-ray studies on the sub-microsecond timescale at synchrotron light sources is reviewed, modelled and examined experimentally. LYSO:Ce is found to be the only commercially available crystal suitable for these experiments. The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits)

  18. Time-resolved measurement of a self-amplified free-electron laser

    International Nuclear Information System (INIS)

    We report on a time-resolved measurement of self-amplified spontaneous emission free-electron laser (FEL) pulses. We observed that the spikes in such FEL pulses have an intrinsic positive chirp and the energy chirp in the electron bunch mapped directly into the FEL output. The measurement also provides rich information on the statistics of the FEL pulses

  19. Time-resolved proton polarisation (TPP) images tyrosyl radical sites in bovine liver catalase.

    Science.gov (United States)

    Zimmer, Oliver; Jouve, Hélène M.; Stuhrmann, Heinrich B.

    2017-05-01

    A differentiation between dynamic polarised protons close to tyrosyl radical sites in catalase and those of the bulk is achieved by time-resolved polarised neutron scattering. Three radical sites, all of them being close to the molecular centre and the heme, appear to be equally possible. Among these is tyr-369 the radial site of which had previously been proven by EPR.

  20. Evidence for a novel mechanism of time-resolved flavin fluorescence depolarization in glutathione reductase.

    NARCIS (Netherlands)

    Berg, van den P.A.W.; Hoek, van A.; Visser, A.J.W.G.

    2004-01-01

    Time-resolved flavin fluorescence anisotropy studies on glutathione reductase (GR) have revealed a remarkable new phenomenon: wild-type GR displays a rapid process of fluorescence depolarization, that is absent in mutant enzymes lacking a nearby tyrosine residue that blocks the NADPH-binding cleft.

  1. Recent Advances in Fluorescence Lifetime Analytical Microsystems: Contact Optics and CMOS Time-Resolved Electronics.

    Science.gov (United States)

    Wei, Liping; Yan, Wenrong; Ho, Derek

    2017-12-04

    Fluorescence spectroscopy has become a prominent research tool with wide applications in medical diagnostics and bio-imaging. However, the realization of combined high-performance, portable, and low-cost spectroscopic sensors still remains a challenge, which has limited the technique to the laboratories. A fluorescence lifetime measurement seeks to obtain the characteristic lifetime from the fluorescence decay profile. Time-correlated single photon counting (TCSPC) and time-gated techniques are two key variations of time-resolved measurements. However, commercial time-resolved analysis systems typically contain complex optics and discrete electronic components, which lead to bulkiness and a high cost. These two limitations can be significantly mitigated using contact sensing and complementary metal-oxide-semiconductor (CMOS) implementation. Contact sensing simplifies the optics, whereas CMOS technology enables on-chip, arrayed detection and signal processing, significantly reducing size and power consumption. This paper examines recent advances in contact sensing and CMOS time-resolved circuits for the realization of fully integrated fluorescence lifetime measurement microsystems. The high level of performance from recently reported prototypes suggests that the CMOS-based contact sensing microsystems are emerging as sound technologies for application-specific, low-cost, and portable time-resolved diagnostic devices.

  2. Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

    DEFF Research Database (Denmark)

    Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank

    2016-01-01

    Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IR...

  3. Combined time-resolved SAXS and X-ray Spectroscopy methods

    NARCIS (Netherlands)

    Bras, W.; Nikitenko, S.; Portale, G.; Beale, A.M.; van der Eerden, A.M.J.; Detollenaere, D.

    2013-01-01

    Recently developed equipment suitable for quasi simultaneous data collection of SAXS/WAXS and X-ray spectroscopy is discussed. The main applications for this technique are foreseen to be time-resolved studies in inorganic materials relevant for catalysis research and ceramics. The equipment is

  4. Time-Resolved Analysis of High-Power-Laser Produced Plasma Expansion in Vacuum

    International Nuclear Information System (INIS)

    Aliverdiev, A.; Batani, D.; Dezulian, R.; Malka, V.; Vinci, T.; Koenig, M.; Benuzzi-Mounaix, A.

    2005-01-01

    Here we consider the results of an experimental investigation of the temporal evolution of plasmas produced by high power laser irradiation of various types of target materials. The experiment was performed at the LULI Laboratory (Ecole Polytechnique, Paris). We have developed a method to analyze time-resolved streak-camera images and analyzed a number of results obtained with various materials

  5. TIME-RESOLVED INFRARED SPECTROSCOPY IN THE U121R BEAMLINE AT THE NSLS

    Energy Technology Data Exchange (ETDEWEB)

    CARR,G.L.; LAVEIGNE,J.D.; LOBO,R.P.S.M.; REITZE,D.H.; TANNER,D.B.

    1999-07-19

    A facility for performing time-resolved infrared spectroscopy has been developed at the NSLS, primarily at beamline U12IR. The pulsed IR light from the synchrotron is used to perform pump-probe spectroscopy. The authors present here a description of the facility and results for the relaxation of photoexcitations in both a semiconductor and superconductor.

  6. Finite-difference time-domain analysis of time-resolved terahertz spectroscopy experiments

    DEFF Research Database (Denmark)

    Larsen, Casper; Cooke, David G.; Jepsen, Peter Uhd

    2011-01-01

    In this paper we report on the numerical analysis of a time-resolved terahertz (THz) spectroscopy experiment using a modified finite-difference time-domain method. Using this method, we show that ultrafast carrier dynamics can be extracted with a time resolution smaller than the duration of the THz...

  7. TIME-RESOLVED INFRARED SPECTROSCOPY IN THE U121R BEAMLINE AT THE NSLS

    International Nuclear Information System (INIS)

    CARR, G.L.; LAVEIGNE, J.D.; LOBO, R.P.S.M.; REITZE, D.H.; TANNER, D.B.

    1999-01-01

    A facility for performing time-resolved infrared spectroscopy has been developed at the NSLS, primarily at beamline U12IR. The pulsed IR light from the synchrotron is used to perform pump-probe spectroscopy. The authors present here a description of the facility and results for the relaxation of photoexcitations in both a semiconductor and superconductor

  8. Time Resolved Shadowgraph Images of Silicon during Laser Ablation:Shockwaves and Particle Generation

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.Y.; Mao, X.L.; Greif, R.; Russo, R.E.

    2006-05-06

    Time resolved shadowgraph images were recorded of shockwaves and particle ejection from silicon during laser ablation. Particle ejection and expansion were correlated to an internal shockwave resonating between the shockwave front and the target surface. The number of particles ablated increased with laser energy and was related to the crater volume.

  9. Chilling injury in stored nectarines and its detection by time-resolved reflectance spectroscopy

    NARCIS (Netherlands)

    Lurie, S.; Vanoli, M.; Dagar, A.; Weksler, A.; Eccher Zerbini, P.C.; Spinelli, L.; Torricelli, A.; Lovati, F.; Feng, R.; Rizzolo, A.

    2011-01-01

    Nectarine fruit after cold storage soften normally, but become dry instead of juicy and can develop flesh browning, bleeding and a gel-like or glassy formation of the flesh near the pit. An experiment was conducted to see if time-resolved reflectance spectroscopy could distinguish these internal

  10. Simultaneous reference and differential waveform acquisition in time-resolved terahertz spectroscopy

    DEFF Research Database (Denmark)

    Iwaszczuk, Krzysztof; Cooke, David; Fujiwara, Masazumi

    2009-01-01

    We present a new method for data acquisition in time-resolved terahertz spectroscopy experiments. Our approach is based on simultaneous collection of reference and differential THz scans. Both the optical THz generation beam and the pump beam are modulated at two different frequencies that are no...

  11. Time-resolved VUV spectroscopy in the EXTRAP-T2 reversed field pinch

    Science.gov (United States)

    Hedqvist, Anders; Rachlew-Källne, Elisabeth

    1998-09-01

    Time-resolved VUV spectroscopy has been used to investigate the effects of impurities in a reversed field pinch operating with a resistive shell. Results of electron temperature, impurity ion densities, particle confinement time and 0741-3335/40/9/004/img1 together with a description of the interpretation and the equipment are presented.

  12. Information Circulars

    International Nuclear Information System (INIS)

    1965-01-01

    Information circulars are published from time to time under the symbol INFCIRC/. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current on 31 December 1964 is given, followed by an index to their subject matter.

  13. Information circulars

    International Nuclear Information System (INIS)

    1997-02-01

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to February 1997, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

  14. Information circulars

    International Nuclear Information System (INIS)

    1992-08-01

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. This revision contains INFCIRCs published up to mid-August 1992. A complete numerical lift of Information Circulars with their titles is reproduced in an Annex

  15. Information circulars

    International Nuclear Information System (INIS)

    1999-06-01

    The document summarizes the Information Circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Member States. This revision contains INFCIRCs published up to the end of May 1999, grouped by field of activity. A complete list of information circulars in numerical order is given in an annex

  16. Information circulars

    International Nuclear Information System (INIS)

    1994-08-01

    Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to mid-August 1994. A complete numerical list of information circulars is reproduced with their titles in the Annex

  17. Information Circulars

    International Nuclear Information System (INIS)

    1966-01-01

    Information circulars are published from time to time under the symbol INFCIRC/. . . . for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A list of the circulars that were current or on the press on 15 May 1966 is given, followed by an index to their subject matter.

  18. Information circulars

    International Nuclear Information System (INIS)

    2002-05-01

    Information circulars are published from time to time under the symbol INFCIRC/... for the purpose of bringing matters of general interest to the attention of all Members of the Agency. The present revision contains INFCIRCs published up to the end of April 2002. A complete numerical list of information circulars is reproduced with their titles in the Annex

  19. Usefulness of time-resolved projection MRA on evaluation of hemodynamics in cerebral occlusive diseases

    International Nuclear Information System (INIS)

    Oka, Yoshihisa; Kusunoki, Katsusuke; Nochide, Ichiro; Igase, Keiji; Harada, Hironobu; Sadamoto, Kazuhiko; Nagasawa, Kiyoshi

    2001-01-01

    The usefulness for evaluation of cerebral hemodynamics using time-resolved projection MRA was studied in normal volunteers and patients of cerebrovascular diseases. Six normal volunteers and ten patients with cerebrovascular occlusive diseases including 6 of IC occlusion and 4 of post EC/IC bypass surgery underwent time-resolved projection MRA on a 1.5 T clinical MRI system. Projection angiograms are acquired with 2D-fast SPGR sequence with a time resolution of approximately one image per second, 40 images being acquired consecutively before and after bolus injection Gd-DTPA. And all images were calculated by complex subtraction from the background mask in a work station. In normal volunteers, the quality of images of time-resolved projection MRA was satisfactory. The arteries from internal carotid artery through M2 segment of middle cerebral artery and all major venous systems were well portrayed. In 4 cases of IC occlusion who were assessed the collateral flow through the anterior communicating artery and posterior communicating artery, there were delayed to demonstrate the ipsilateral MCA. However, in 2 cases of IC occlusion that were assessed the collateral flow through leptomeningeal anastomosis, ipsilateral MCA and collateral circulation were not demonstrated. In all patients of post EC/IC bypass surgery, the patency of EC/IC bypass could be evaluated as properly with time-resolved projection MRA as 3D-TOF MRA. Although the temporal and spatial resolutions are insufficient, time-resolved projection MRA was power-full non-invasive method to evaluate the cerebral hemodynamics vis the basal communicating arteries in IC occlusion and identify the patency of EC/IC bypass. (author)

  20. Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements

    Science.gov (United States)

    Clerc, F.; Njiki-Menga, G.-H.; Witschger, O.

    2013-04-01

    Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a

  1. Exploratory study on a statistical method to analyse time resolved data obtained during nanomaterial exposure measurements

    International Nuclear Information System (INIS)

    Clerc, F; Njiki-Menga, G-H; Witschger, O

    2013-01-01

    Most of the measurement strategies that are suggested at the international level to assess workplace exposure to nanomaterials rely on devices measuring, in real time, airborne particles concentrations (according different metrics). Since none of the instruments to measure aerosols can distinguish a particle of interest to the background aerosol, the statistical analysis of time resolved data requires special attention. So far, very few approaches have been used for statistical analysis in the literature. This ranges from simple qualitative analysis of graphs to the implementation of more complex statistical models. To date, there is still no consensus on a particular approach and the current period is always looking for an appropriate and robust method. In this context, this exploratory study investigates a statistical method to analyse time resolved data based on a Bayesian probabilistic approach. To investigate and illustrate the use of the this statistical method, particle number concentration data from a workplace study that investigated the potential for exposure via inhalation from cleanout operations by sandpapering of a reactor producing nanocomposite thin films have been used. In this workplace study, the background issue has been addressed through the near-field and far-field approaches and several size integrated and time resolved devices have been used. The analysis of the results presented here focuses only on data obtained with two handheld condensation particle counters. While one was measuring at the source of the released particles, the other one was measuring in parallel far-field. The Bayesian probabilistic approach allows a probabilistic modelling of data series, and the observed task is modelled in the form of probability distributions. The probability distributions issuing from time resolved data obtained at the source can be compared with the probability distributions issuing from the time resolved data obtained far-field, leading in a

  2. Time resolved reversal of spin-spiral domains by an electric field in multiferroic MnWO{sub 4}

    Energy Technology Data Exchange (ETDEWEB)

    Thielen, Philip; Hoffmann, Tim; Fiebig, Manfred [University Bonn, HISKP (Germany); Becker, Petra; Bohaty, Ladislav [Institut fuer Kristallographie, Universitaet Koeln (Germany)

    2011-07-01

    The interaction of magnetic and ferroelectric order is intrinsically strong in spin-spiral multiferroics. Here the complex magnetic long range order breaks inversion symmetry and induces a spontaneous electric polarization. The interaction allows for switching of the magnetization by means of an applied electric field and is thus of great interest for possible applications. So far there exists little information on the time scale and dynamics of the actual switching process. Here we report time resolved measurements of the reversal of spin-spiral domains in multiferroic MnWO{sub 4} by optical second harmonic generation. Magnetic single-domain states are created by the application of an electric field. By reversing its polarity, a reversal of the magnetic domain state occurs. The time scale of the dynamic switching process is found to be in the ms region. Images of the domain-reversal process are obtained. The dynamic domain pattern differs substantially from that of quasi-statically switched multi domain structures.

  3. Analytical formulation for modulation of time-resolved dynamical Franz-Keldysh effect by electron excitation in dielectrics

    Science.gov (United States)

    Otobe, T.

    2017-12-01

    Analytical formulation of subcycle modulation (SCM) of dielectrics including electron excitation is presented. The SCM is sensitive to not only the time-resolved dynamical Franz-Keldysh effect (Tr-DFKE) [T. Otobe et al., Phys. Rev. B 93, 045124 (2016), 10.1103/PhysRevB.93.045124], which is the nonlinear response without the electron excitation, but also the excited electrons. The excited electrons enhance the modulation with even harmonics of pump laser frequency, and generate the odd-harmonics components. The new aspect of SCM is a consequence of (i) the interference between the electrons excited by the pump laser and those excited by the probe-pulse laser and (ii) oscillation of the generated wave packed by the pump laser. When the probe- and pump-pulse polarizations are parallel, the enhancement of the even harmonics and the generation of the odd-harmonics modulation appear. However, if the polarizations are orthogonal, the effect arising from the electron excitations becomes weak. By comparing the parabolic and cosine band models, I found that the electrons under the intense laser field move as quasifree particles.

  4. Quantum-dot-based homogeneous time-resolved fluoroimmunoassay of alpha-fetoprotein

    Energy Technology Data Exchange (ETDEWEB)

    Chen Meijun; Wu Yingsong; Lin Guanfeng; Hou Jingyuan; Li Ming [Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, 510515 (China); Liu Tiancai, E-mail: liutc@smu.edu.cn [Institute of Antibody Engineering, School of Biotechnology, Southern Medical University, Guangzhou, 510515 (China)

    2012-09-05

    Highlights: Black-Right-Pointing-Pointer QDs-based homogeneous time-resolved fluoroimmunoassay was developed to detect AFP. Black-Right-Pointing-Pointer The conjugates were prepared with QDs-doped microspheres and anti-AFP McAb. Black-Right-Pointing-Pointer The conjugates were prepared with LTCs and another anti-AFP McAb. Black-Right-Pointing-Pointer Excess amounts of conjugates were used for detecting AFP without rinsing. Black-Right-Pointing-Pointer The wedding of QPs and LTCs was suitable for HTRFIA to detect AFP. - Abstract: Quantum dots (QDs) with novel photoproperties are not widely used in clinic diagnosis, and homogeneous time-resolved fluorescence assays possess many advantages over current methods for alpha-fetoprotein (AFP) detection. A novel QD-based homogeneous time-resolved fluorescence assay was developed and used for detection of AFP, a primary marker for many cancers and diseases. QD-doped carboxyl-modified polystyrene microparticles (QPs) were prepared by doping oil-soluble QDs possessing a 605 nm emission peak. The antibody conjugates (QPs-E014) were prepared from QPs and an anti-AFP monoclonal antibody, and luminescent terbium chelates (LTCs) were prepared and conjugated to a second anti-AFP monoclonal antibody (LTCs-E010). In a double-antibodies sandwich structure, QPs-E014 and LTCs-E010 were used for detection of AFP, serving as energy acceptor and donor, respectively, with an AFP bridge. The results demonstrated that the luminescence lifetime of these QPs was sufficiently long for use in a time-resolved fluoroassay, with the efficiency of time-resolved Foerster resonance transfer (TR-FRET) at 67.3% and the spatial distance of the donor to acceptor calculated to be 66.1 Angstrom-Sign . Signals from TR-FRET were found to be proportional to AFP concentrations. The resulting standard curve was log Y = 3.65786 + 0.43863{center_dot}log X (R = 0.996) with Y the QPs fluorescence intensity and X the AFP concentration; the calculated sensitivity was 0

  5. Information Circulars

    International Nuclear Information System (INIS)

    1973-01-01

    Information circulars are published from time to time under the symbol INFCIRC/.. for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A subject index to the circulars is presented overleaf. It covers all those published in the last five years (that is, since the beginning of 1968 and ending with INFCIRC/192), as well as others which, for one reason or another, are still considered to be of current rather than merely historical interest. Such circulars can be traced by reference to the indexes that were included in earlier revisions of the present document.

  6. Time-resolved four-wave mixing in InAs/InGaAs quantum-dot amplifiers under electrical injection

    DEFF Research Database (Denmark)

    Borri, Paola; Langbein, Wolfgang Werner; Hvam, Jørn Märcher

    2000-01-01

    Time-resolved four-wave mixing in an InAs/InGaAs/GaAs electrically pumped quantum-dot amplifier is measured at room temperature for different applied bias currents going from optical absorption to gain of the device. The four-wave mixing signal from 140 fs pulses shows a transition from a delayed...... photon-echo response in the absorption regime to a prompt free polarization decay in the gain regime. This corresponds to a pronounced reduction of the dephasing time from 250 fs at zero bias to less than 50 fs at the maximum applied current. The four-wave mixing response at transparency of the device...

  7. Time-resolved X-ray scattering program at the Advanced Photon Source

    International Nuclear Information System (INIS)

    Rodricks, B.

    1994-01-01

    The Time-Resolved Scattering Program's goal is the development of instruments and techniques for time-resolved studies. This entails the development of wide bandpass and focusing optics, high-speed detectors, mechanical choppers, and components for the measurement and creation of changes in samples. Techniques being developed are pump-probe experiments, single-bunch scattering experiments, high-speed white and pink beam Laue scattering, and nanosecond to microsecond synchronization of instruments. This program will be carried out primarily from a white-beam, bend-magnet source, experimental station, 1-BM-B, that immediately follows the first optics enclosure (1-BM-A). This paper will describe the experimental station and instruments under development to carry out the program

  8. Identifiability of models for time-resolved fluorescence with underlying distributions of rate constants.

    Science.gov (United States)

    Boens, Noël; Van der Auweraer, Mark

    2014-02-01

    The deterministic identifiability analysis of photophysical models for the kinetics of excited-state processes, assuming errorless time-resolved fluorescence data, can verify whether the model parameters can be determined unambiguously. In this work, we have investigated the identifiability of several uncommon models for time-resolved fluorescence with underlying distributions of rate constants which lead to non-exponential decays. The mathematical functions used here for the description of non-exponential fluorescence decays are the stretched exponential or Kohlrausch function, the Becquerel function, the Förster type energy transfer function, decay functions associated with exponential, Gaussian and uniform distributions of rate constants, a decay function with extreme sub-exponential behavior, the Mittag-Leffler function and Heaviside's function. It is shown that all the models are uniquely identifiable, which means that for each specific model there exists a single parameter set that describes its associated fluorescence δ-response function.

  9. Time-resolved protein nano-crystallography using an X-ray free-electron laser

    International Nuclear Information System (INIS)

    Aquila, Andrew; Hunter, Mark S.; Fromme, Petra; Fromme, Raimund; Grotjohann, Ingo; Doak, R. Bruce; Kirian, Richard A.; Schmidt, Kevin E.; Wang, Xiaoyu; Weierstall, Uwe; Spence, John C.H.; White, Thomas A.; Caleman, Carl; DePonte, Daniel P.; Fleckenstein, Holger; Gumprecht, Lars; Liang, Mengning; Martin, Andrew V.; Schulz, Joachim; Stellato, Francesco; Stern, Stephan; Barty, Anton; Andreasson, Jakob; Davidsson, Jan; Hajdu, Janos; Maia, Filipe R.N.C.; Seibert, M. Marvin; Timneanu, Nicusor; Arnlund, David; Johansson, Linda; Malmerberg, Erik; Neutze, Richard; Bajt, Sasa; Barthelmess, Miriam; Graafsma, Heinz; Hirsemann, Helmut; Wunderer, Cornelia; Barends, Thomas R.M.; Foucar, Lutz; Krasniqi, Faton; Lomb, Lukas; Rolles, Daniel; Schlichting, Ilme; Schmidt, Carlo; Bogan, Michael J.; Hampton, Christina Y.; Sierra, Raymond; Starodub, Dmitri; Bostedt, Christoph; Bozek, John D.; Messerschmidt, Marc; Williams, Garth J.; Bottin, Herve

    2012-01-01

    We demonstrate the use of an X-ray free electron laser synchronized with an optical pump laser to obtain X-ray diffraction snapshots from the photo-activated states of large membrane protein complexes in the form of nano-crystals flowing in a liquid jet. Light-induced changes of Photosystem I-Ferredoxin co-crystals were observed at time delays of 5 to 10 μs after excitation. The result correlates with the microsecond kinetics of electron transfer from Photosystem I to ferredoxin. The undocking process that follows the electron transfer leads to large rearrangements in the crystals that will terminally lead to the disintegration of the crystals. We describe the experimental setup and obtain the first time resolved femtosecond serial X-ray crystallography results from an irreversible photo-chemical reaction at the Linac Coherent Light Source. This technique opens the door to time-resolved structural studies of reaction dynamics in biological systems. (authors)

  10. Time-resolved wave profile measurements in copper to Megabar pressures

    Energy Technology Data Exchange (ETDEWEB)

    Chhabildas, L C; Asay, J R

    1981-01-01

    Many time-resolved techniques have been developed which have greatly aided in the understanding of dynamic material behavior such as the high pressure-dynamic strength of materials. In the paper, time-resolved measurements of copper (at shock-induced high pressures and temperatures) are used to illustrate the capability of using such techniques to investigate high pressure strength. Continuous shock loading and release wave profiles have been made in copper to 93 GPa using velocity interferometric techniques. Fine structure in the release wave profiles from the shocked state indicates an increase in shear strength of copper to 1.5 GPa at 93 GPa from its ambient value of 0.08 GPa.

  11. Mix and Inject: Reaction Initiation by Diffusion for Time-Resolved Macromolecular Crystallography

    Directory of Open Access Journals (Sweden)

    Marius Schmidt

    2013-01-01

    Full Text Available Time-resolved macromolecular crystallography unifies structure determination with chemical kinetics, since the structures of transient states and chemical and kinetic mechanisms can be determined simultaneously from the same data. To start a reaction in an enzyme, typically, an initially inactive substrate present in the crystal is activated. This has particular disadvantages that are circumvented when active substrate is directly provided by diffusion. However, then it is prohibitive to use macroscopic crystals because diffusion times become too long. With small micro- and nanocrystals diffusion times are adequately short for most enzymes and the reaction can be swiftly initiated. We demonstrate here that a time-resolved crystallographic experiment becomes feasible by mixing substrate with enzyme nanocrystals which are subsequently injected into the X-ray beam of a pulsed X-ray source.

  12. Time-resolved imaging using x-ray free electron lasers

    International Nuclear Information System (INIS)

    Barty, Anton

    2010-01-01

    The ultra-intense, ultra-short x-ray pulses provided by x-ray free electron laser (XFEL) sources are ideally suited to time-resolved studies of structural dynamics with spatial resolution from nanometre to atomic length scales and a temporal resolution of 10 fs or less. With enough photons in a single pulse to enable single-shot measurements and short enough pulses to freeze atomic motion, researchers now have a new window into the time evolution ultrafast phenomena that are intrinsically not cyclic in nature. In this paper we recap some of the key time-resolved imaging experiments performed at FLASH and look ahead to a new generation of experiments at higher resolution using a new generation of new XFEL sources that are only just becoming available.

  13. Timepix3 as X-ray detector for time resolved synchrotron experiments

    Energy Technology Data Exchange (ETDEWEB)

    Yousef, Hazem, E-mail: hazem.yousef@diamond.ac.uk; Crevatin, Giulio; Gimenez, Eva N.; Horswell, Ian; Omar, David; Tartoni, Nicola

    2017-02-11

    The Timepix3 ASIC can be used very effectively for time resolved experiments at synchrotron facilities. We have carried out characterizations with the synchrotron beam in order to determine the time resolution and other characteristics such as the energy resolution, charge sharing and signals overlapping. The best time resolution achieved is 19 ns FWHM for 12 keV photons and 350 V bias voltage. The time resolution shows dependency on the photon energy as well as on the chip and acquisition parameters. - Highlights: • An estimate time resolution of the Timepix3 is produced based on the arrival time. • At high resolution, the time structure of the DLS synchrotron beam is resolved. • The arrival time information improves combining the charge split events. • The results enable performing a wide range of time resolved experiments.

  14. A review of in situ and/or time resolved neutron scattering

    International Nuclear Information System (INIS)

    Isnard, O.

    2007-01-01

    Thanks to the ability of neutrons to penetrate deep into matter, experiments can be performed in situ in real conditions. The development of dedicated instruments on high flux neutron sources also enables fast data acquisition. As a consequence, it is now possible to investigate not only in situ but also time resolved physical or chemical processes over several time scales ranging from hours to a few milliseconds. Several recent examples are taken in different fields of research: physics, magnetism, chemistry, metallurgy, electrochemistry, polymers and to get information from archaeological objects. Among the scattering techniques that can be used to perform in situ or time resolved experiments we present results of powder neutron diffraction, small angle neutron scattering, and neutron radiography. (author)

  15. Broad-band time-resolved near infrared spectroscopy in the TJ-II stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, M.C.; Pastor, I.; Cal, E. de la; McCarthy, K.J. [Laboratorio Nacional de Fusion, CIEMAT, Madrid (Spain); Diaz, D. [Universidad Autonoma de Madrid, Dept Quimica Fisica Aplicada, Madrid (Spain)

    2014-11-15

    First experimental results on broad-band, time-resolved Near Infrared (NIR;here loosely defined as covering from 750 to 1650 nm) passive spectroscopy using a high sensitivity InGaAs detector are reported for the TJ-II Stellarator. Experimental set-up is described together with its main characteristics, the most remarkable ones being its enhanced NIR response, broadband spectrum acquisition in a single shot, and time-resolved measurements with up to 1.8 kHz spectral rate. Prospects for future work and more extended physics studies in this newly open spectral region in TJ-II are discussed. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Time-resolved resonance fluorescence spectroscopy for study of chemical reactions in laser-induced plasmas.

    Science.gov (United States)

    Liu, Lei; Deng, Leimin; Fan, Lisha; Huang, Xi; Lu, Yao; Shen, Xiaokang; Jiang, Lan; Silvain, Jean-François; Lu, Yongfeng

    2017-10-30

    Identification of chemical intermediates and study of chemical reaction pathways and mechanisms in laser-induced plasmas are important for laser-ablated applications. Laser-induced breakdown spectroscopy (LIBS), as a promising spectroscopic technique, is efficient for elemental analyses but can only provide limited information about chemical products in laser-induced plasmas. In this work, time-resolved resonance fluorescence spectroscopy was studied as a promising tool for the study of chemical reactions in laser-induced plasmas. Resonance fluorescence excitation of diatomic aluminum monoxide (AlO) and triatomic dialuminum monoxide (Al 2 O) was used to identify these chemical intermediates. Time-resolved fluorescence spectra of AlO and Al 2 O were used to observe the temporal evolution in laser-induced Al plasmas and to study their formation in the Al-O 2 chemistry in air.

  17. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    DEFF Research Database (Denmark)

    Ankjærgaard, Christina

    to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical...... stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration...... an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling through the shallow traps. The results from feldspars show the relative roles of an IR excited state (IR resonance), band tails...

  18. Recent applications of multiwire proportional chambers for time resolved studies on muscle

    Energy Technology Data Exchange (ETDEWEB)

    Faruqi, A.R.; Huxley, H.E.; Kress, M.

    1986-12-01

    The use of multiwire proportional chambers has played an important role in recording time resolved data from vertebrate muscle under various physiological conditions from which we have selected two examples from recent work. The first example describes the measurement of the equatorial pattern along with measurements of the muscle sarcomere length showing that the delay in tension development relative to changes in the X-ray intensity are not due to ''internal'' shortening in the muscle. The second example describes time-resolved measurements on the thin filament activation process, studied with both a linear and an area detector. The results show clearly that changes in thin filament structure precede cross-bridge formation producing further strong evidence for the ''steric blocking model'' for muscle contraction.

  19. A direct electron detector for time-resolved MeV electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Vecchione, T.; Denes, P.; Jobe, R. K.; Johnson, I. J.; Joseph, J. M.; Li, R. K.; Perazzo, A.; Shen, X.; Wang, X. J.; Weathersby, S. P.; Yang, J.; Zhang, D.

    2017-03-01

    The introduction of direct electron detectors enabled the structural biology revolution of cryogenic electron microscopy. Direct electron detectors are now expected to have a similarly dramatic impact on time-resolved MeV electron microscopy, particularly by enabling both spatial and temporal jitter correction. Here we report on the commissioning of a direct electron detector for time-resolved MeV electron microscopy. The direct electron detector demonstrated MeV single electron sensitivity and is capable of recording megapixel images at 180 Hz. The detector has a 15-bit dynamic range, better than 30-μmμm spatial resolution and less than 20 analogue-to-digital converter count RMS pixel noise. The unique capabilities of the direct electron detector and the data analysis required to take advantage of these capabilities are presented. The technical challenges associated with generating and processing large amounts of data are also discussed.

  20. MCNP simulations of a new time-resolved Compton scattering imaging technique

    International Nuclear Information System (INIS)

    Ilan, Y.

    2004-01-01

    Medical images of human tissue can be produced using Computed Tomography (CT), Positron Emission Tomography (PET), Ultrasound or Magnetic Resonance Imaging (MRI). In all of the above techniques, in order to get a three-dimensional (3D) image, one has to rotate or move the source, the detectors or the scanned target. This procedure is complicated, time consuming and increases the cost and weight of the scanning equipment. Time resolved optical tomography has been suggested as an alternative to the above conventional methods. This technique implies near infrared light (NIR) and fast time-resolved detectors to obtain a 3D image of the scanned target. However, due to the limited penetration of the NIR light in the tissue, the application of this technique is limited to soft tissue like a female breast or a premature infant brain

  1. Time resolved bovine host reponse to virulence factors mapped in milk by selected reaction monitoring

    DEFF Research Database (Denmark)

    Bislev, Stine Lønnerup; Kusebauch, Ulrike; Codrea, Marius Cosmin

    in milk samples from cows challenged with peptidoglycan (PGN) from the gram-positive bacteria Staphylococcus aureus and lipopolysaccharide (LPS) from the gram-negative bacteria Escherichia coli for 54 hours. This method allowed for the first time a thorough proteome analysis of the time-resolved response...... to gram-positive and gram-negative cell wall components. The results demonstrated that the extent of protein regulation is much larger after challenge with LPS than with PGN underpinning the growing evidence that gram-negative bacteria cause a far more acute host response than gram-positive bacteria......TIME RESOLVED BOVINE HOST RESPONSE TO VIRULENCE FACTORS, MAPPED IN MILK BY SELECTED REACTION MONITORING S.L. Bislev1, U. Kusebauch2, M.C. Codrea1, R. Moritz2, C.M. Røntved1, E. Bendixen1 1 Department of Animal Science, Faculty of Science and Technology, Aarhus University, Tjele, Denmark; 2...

  2. Circular Updates

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Circular Updates are periodic sequentially numbered instructions to debriefing staff and observers informing them of changes or additions to scientific and specimen...

  3. Time resolved analysis of water drainage in porous asphalt concrete using neutron radiography.

    Science.gov (United States)

    Poulikakos, L D; Sedighi Gilani, M; Derome, D; Jerjen, I; Vontobel, P

    2013-07-01

    Porous asphalt as a road surface layer controls aquaplaning as rain water can drain through its highly porous structure. The process of water drainage through this permeable layer is studied using neutron radiography. Time-resolved water configuration and distribution within the porous structure are reported. It is shown that radiography depicts the process of liquid water transport within the complex geometry of porous asphalt, capturing water films, filled dead end pores and water islands. Copyright © 2013 Elsevier Ltd. All rights reserved.

  4. Ultrafast Structural Dynamics in InSb Probed by Time-Resolved X-Ray Diffraction

    International Nuclear Information System (INIS)

    Chin, A.H.; Shank, C.V.; Chin, A.H.; Schoenlein, R.W.; Shank, C.V.; Glover, T.E.; Leemans, W.P.; Balling, P.

    1999-01-01

    Ultrafast structural dynamics in laser-perturbed InSb are studied using time-resolved x-ray diffraction with a novel femtosecond x-ray source. We report the first observation of a delay in the onset of lattice expansion, which we attribute to energy relaxation processes and lattice strain propagation. In addition, we observe direct indications of ultrafast disordering on a subpicosecond time scale. copyright 1999 The American Physical Society

  5. Time-resolved tunable diode laser absorption spectroscopy of pulsed plasma

    Czech Academy of Sciences Publication Activity Database

    Adámek, Petr; Olejníček, Jiří; Čada, Martin; Kment, Š.; Hubička, Zdeněk

    2013-01-01

    Roč. 38, č. 14 (2013), s. 2428-2430 ISSN 0146-9592 R&D Projects: GA MŠk LH12045; GA ČR(CZ) GAP205/11/0386; GA MŠk LD12002; GA MŠk LH12043 Institutional support: RVO:68378271 Keywords : diode lasers * plasma diagnostics * absorption spectroscopy * time resolved Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.179, year: 2013

  6. Time-resolved phase measurement of a self-amplified free-electron laser

    International Nuclear Information System (INIS)

    We report on the first time-resolved phase measurement on self-amplified spontaneous emission (SASE) free-electron laser (FEL) pulses. We observed that the spikes in the output of such free-electron laser pulses have an intrinsic positive chirp. We also observed that the energy chirp in the electron bunch mapped directly into the FEL output. Under certain conditions, the two chirps cancel each other. The experimental result was compared with simulations and interpreted with SASE theory

  7. Analysis of Aerodynamic Sound Source by Time-Resolved Stereoscopic PIV

    OpenAIRE

    尾花, 功一; 瀬尾, 健彦; 志村, 祐康; 店橋, 護; 宮内, 敏雄; Koichi, OBANA; Takehiko, SEO; Masayasu, SHIMURA; Mamoru, TANAHASHI; Toshio, MIYAUCHI; 東工大院; 東工大院; 東工大院; 東工大院; 東工大院

    2009-01-01

    Investigation of sound generation mechanism in flow fields is important for reduction of aerodynamic sound. The detailed investigation of sound sources requires velocity measurements with high temporal and spatial resolutions. In this study, sound sources in turbulent mixing layer have been investigated by time-resolved stereoscopic particle image velocimetry (PIV). Powell's sound source and Reynolds stress component of Lighthill's sound source have been evaluated from experimental results an...

  8. Many-body dynamics and exciton formation studied by time-resolved photoluminescence

    Science.gov (United States)

    Hoyer, W.; Ell, C.; Kira, M.; Koch, S. W.; Chatterjee, S.; Mosor, S.; Khitrova, G.; Gibbs, H. M.; Stolz, H.

    2005-08-01

    The dynamics of exciton and electron-hole plasma populations is studied via time-resolved photoluminescence after nonresonant excitation. By comparing the peak emission at the exciton resonance with the emission of the continuum, it is possible to experimentally identify regimes where the emission originates predominantly from exciton and/or plasma populations. The results are supported by a microscopic theory which allows one to extract the fraction of bright excitons as a function of time.

  9. The Fourteenth International Meeting on Time-Resolved Vibrational Spectroscopy (TRVS XIV)

    Science.gov (United States)

    2010-02-03

    Shaul Mukamel Oleksiy Roslyak Cyril Falvo and Time Resolved Stimulated Vibrational Spectroscopy with pulse , , , Benoit Palmieri shaping and entagled...Martin Zanni, University of Wisconsin-Madison Residue-by-residue structural and time resolution with pulse shaping 2D IR spectroscopy and isotope...o xp os ves e we , n an ea , ava ur ace ar are en er 12:30 PM Lunch 2:00 PM Vibrational Dynamics in Liquids Presiding: Edwin Heilweil, NIST 2:00 PM

  10. A diagnostic for time-resolved spatial profiles measurements on the ion temperature on JET

    International Nuclear Information System (INIS)

    Brocken, H.J.B.M.; Ven, H.W van der.

    1980-05-01

    A neutral particle scattering experiment for a continuous measurement of the ion temperature and ion density of the JET plasma in the hydrogen and deuterium phase is proposed. Space- and time-resolved measurements are possible by injection of a mono-energetic particle beam into the plasma and from the analysis of the velocity distribution of the scattered particles. The requirements on the injection system are specified and a suitable analyzer system is described

  11. A beamline for time-resolved extreme ultraviolet and soft x-ray spectroscopy

    OpenAIRE

    Grilj, Jakob; Sistrunk, Emily; Koch, Markus; Gühr, Markus

    2013-01-01

    High harmonic generation is a convenient way to obtain extreme ultraviolet light from table-top laser systems and the experimental tools to exploit this simple and powerful light source for time-resolved spectroscopy are being developed by several groups. For these applications, brightness and stability of the high harmonic generation is a key feature. This article focuses on practical aspects in the generation of extreme ultraviolet pulses with ultrafast commercial lasers, namely generation ...

  12. Time-resolved far-infrared experiments at the National Synchrotron Light Source. Final report

    International Nuclear Information System (INIS)

    Tanner, D.B.; Reitze, D.H.; Carr, G.L.

    1999-01-01

    A facility for time-resolved infrared and far-infrared spectroscopy has been built and commissioned at the National Synchrotron Light Source. This facility permits the study of time dependent phenomena over a frequency range from 2-8000cm -1 (0.25 meV-1 eV). Temporal resolution is approximately 200 psec and time dependent phenomena in the time range out to 100 nsec can be investigated

  13. Time-resolved laser-induced fluorescence in the nuclear fuel cycle

    International Nuclear Information System (INIS)

    Moulin, C.; Decambox, P.; Mauchien, P.; Petit, A.

    1995-01-01

    Time-Resolved Laser-Induced Fluorescence (TRLIF) is a very sensitive and selective method that has been used for actinides and lanthanides analysis in the nuclear fuel cycle. This technique has been used in different fields such as in geology, in the Purex process, in the environment, in the medical and in waste storage assessment. Spectroscopic data, limits of detection and results obtained in previously quoted fields are presented. (author)

  14. Subcellular localization-dependent changes in EGFP fluorescence lifetime measured by time-resolved flow cytometry

    OpenAIRE

    Gohar, Ali Vaziri; Cao, Ruofan; Jenkins, Patrick; Li, Wenyan; Houston, Jessica P.; Houston, Kevin D.

    2013-01-01

    Intracellular protein transport and localization to subcellular regions are processes necessary for normal protein function. Fluorescent proteins can be fused to proteins of interest to track movement and determine localization within a cell. Currently, fluorescence microscopy combined with image processing is most often used to study protein movement and subcellular localization. In this contribution we evaluate a high-throughput time-resolved flow cytometry approach to correlate intracellul...

  15. Time-resolved SAXS/WAXS study of phase behaviour and crystallization in polymer blends

    Czech Academy of Sciences Publication Activity Database

    Baldrian, Josef; Steinhart, Miloš; Vlček, Petr; Horký, M.; Laggner, P.; Amenitsch, H.; Bernstorff, S.

    B41, 4-6 (2002), s. 1023-1032 ISSN 0022-2348 R&D Projects: GA ČR GA106/99/0557 Institutional research plan: CEZ:AV0Z4050913 Keywords : time-resolved SAXS/WAXS * poly(ethylene oxide)/poly(methyl methacrylate) blends * phase separation Subject RIV: JJ - Other Materials Impact factor: 0.677, year: 2002

  16. Optimization of experimental conditions in uranium trace determination using laser time-resolved fluorimetry

    International Nuclear Information System (INIS)

    Baly, L.; Garcia, M.A.

    1996-01-01

    At the present paper a new sample excitation geometry is presented for the uranium trace determination in aqueous solutions by the Time-Resolved Laser-Induced Fluorescence. This new design introduces the laser radiation through the top side of the cell allowing the use of cells with two quartz sides, less expensive than commonly used at this experimental set. Optimization of the excitation conditions, temporal discrimination and spectral selection are presented

  17. Singular value decomposition as a tool for background corrections in time-resolved XFEL scattering data

    DEFF Research Database (Denmark)

    Haldrup, Kristoffer

    2014-01-01

    The development of new X-ray light sources, XFELs, with unprecedented time and brilliance characteristics has led to the availability of very large datasets with high time resolution and superior signal strength. The chaotic nature of the emission processes in such sources as well as entirely nov...... on singular-value decomposition of no-signal subsets of acquired datasets in combination with model inputs and appears generally applicable to time-resolved X-ray diffuse scattering experiments....

  18. 3C velocity field measurement in microscale using time resolved micro-PIV

    OpenAIRE

    N., Erkan; K., Okamoto; Dept. of Quantum Eng. and Sys. Science, The University of Tokyo; Inst. of Env. Studies, The University of Tokyo

    2007-01-01

    Measurement of the 3C velocity field in the microfluidic devices with the conventional techniques and conventional micro-PIV is still difficult due to the limited optical access to the microscale flow fields. Mainly micro PIV vector field realizations have been remained limited to 2C velocities. In this study, 3C velocity measurement in microscale using 2-dimentional time-resolved micro PIV images is proposed. The method is based on the PIV performs cross-correlation (CC) peak height tracking...

  19. Time-resolved small-angle neutron scattering study on soap-free emulsion polymerization

    International Nuclear Information System (INIS)

    Motokawa, Ryuhei; Koizumi, Satoshi; Hashimoto, Takeji; Nakahira, Takayuki; Annaka, Masahiko

    2006-01-01

    We investigated an aqueous soap-free emulsion polymerization process of Poly(N-isopropylacrylamide)-block-poly(ethylene glycol) by ultra-small-angle and time-resolved small-angle neutron scattering methods. The results indicate that the compartmentalization of chain end radicals into solid-like micelle cores crucially leads to the quasi-living behavior of the radical polymerization by prohibiting recombination process

  20. Information circulars

    International Nuclear Information System (INIS)

    1987-06-01

    The document summarizes the information circulars published by the IAEA for the purpose of bringing matters of general interest to the attention of all Members of the Agency. In the main body of the document only those documents which are regarded as likely to be of current interest are listed. A complete numerical list of information circulars with their titles is reproduced in the Annex

  1. Watching proteins function with 150-ps time-resolved X-ray crystallography

    Science.gov (United States)

    Anfinrud, Philip

    2007-03-01

    We have used time-resolved Laue crystallography to characterize ligand migration pathways and dynamics in wild-type and several mutant forms of myoglobin (Mb), a ligand-binding heme protein found in muscle tissue. In these pump-probe experiments, which were conducted on the ID09B time-resolved beamline at the European Synchrotron and Radiation Facility, a laser pulse photodissociates CO from an MbCO crystal and a suitably delayed X-ray pulse probes its structure via Laue diffraction. Single-site mutations in the vicinity of the heme pocket docking site were found to have a dramatic effect on ligand migration. To visualize this process, time-resolved electron density maps were stitched together into movies that unveil with <2-å spatial resolution and 150-ps time-resolution the correlated protein motions that accompany and/or mediate ligand migration. These studies help to illustrate at an atomic level relationships between protein structure, dynamics, and function.

  2. Evaluating scintillator performance in time-resolved hard X-ray studies at synchrotron light sources.

    Science.gov (United States)

    Rutherford, Michael E; Chapman, David J; White, Thomas G; Drakopoulos, Michael; Rack, Alexander; Eakins, Daniel E

    2016-05-01

    The short pulse duration, small effective source size and high flux of synchrotron radiation is ideally suited for probing a wide range of transient deformation processes in materials under extreme conditions. In this paper, the challenges of high-resolution time-resolved indirect X-ray detection are reviewed in the context of dynamic synchrotron experiments. In particular, the discussion is targeted at two-dimensional integrating detector methods, such as those focused on dynamic radiography and diffraction experiments. The response of a scintillator to periodic synchrotron X-ray excitation is modelled and validated against experimental data collected at the Diamond Light Source (DLS) and European Synchrotron Radiation Facility (ESRF). An upper bound on the dynamic range accessible in a time-resolved experiment for a given bunch separation is calculated for a range of scintillators. New bunch structures are suggested for DLS and ESRF using the highest-performing commercially available crystal LYSO:Ce, allowing time-resolved experiments with an interframe time of 189 ns and a maximum dynamic range of 98 (6.6 bits).

  3. Time-resolved single-shot terahertz time-domain spectroscopy for ultrafast irreversible processes

    Science.gov (United States)

    Zhai, Zhao-Hui; Zhong, Sen-Cheng; Li, Jun; Zhu, Li-Guo; Meng, Kun; Li, Jiang; Liu, Qiao; Peng, Qi-Xian; Li, Ze-Ren; Zhao, Jian-Heng

    2016-09-01

    Pulsed terahertz spectroscopy is suitable for spectroscopic diagnostics of ultrafast events. However, the study of irreversible or single shot ultrafast events requires ability to record transient properties at multiple time delays, i.e., time resolved at single shot level, which is not available currently. Here by angular multiplexing use of femtosecond laser pulses, we developed and demonstrated a time resolved, transient terahertz time domain spectroscopy technique, where burst mode THz pulses were generated and then detected in a single shot measurement manner. The burst mode THz pulses contain 2 sub-THz pulses, and the time gap between them is adjustable up to 1 ns with picosecond accuracy, thus it can be used to probe the single shot event at two different time delays. The system can detect the sub-THz pulses at 0.1 THz-2.5 THz range with signal to noise ratio (SNR) of ˜400 and spectrum resolution of 0.05 THz. System design was described here, and optimizations of single shot measurement of THz pulses were discussed in detail. Methods to improve SNR were also discussed in detail. A system application was demonstrated where pulsed THz signals at different time delays of the ultrafast process were successfully acquired within single shot measurement. This time resolved transient terahertz time domain spectroscopy technique provides a new diagnostic tool for irreversible or single shot ultrafast events where dynamic information can be extracted at terahertz range within one-shot experiment.

  4. A New Approach to Time-Resolved 3D-PTV

    Science.gov (United States)

    Boomsma, Aaron; Troolin, Dan; Bjorkquist, Dan; TSI Inc Team

    2017-11-01

    Volumetric three-component velocimetry via particle tracking is a powerful alternative to TomoPIV. It has been thoroughly documented that compared to TomoPIV, particle tracking velocimetry (PTV) methods (whether 2D or 3D) better resolve regions of high velocity gradient, identify fewer ghost particles, and are less computationally demanding, which results in shorter processing times. Recently, 3D-PTV has seen renewed interest in the PIV community with the availability of time-resolved data. Of course, advances in hardware are partly to thank for that availability-higher speed cameras, more effective memory management, and higher speed lasers. But in software, algorithms that utilize time resolved data to improve 3D particle reconstruction and particle tracking are also under development and advancing (e.g. shake-the-box, neighbor tracking reconstruction, etc.). .In the current study, we present a new 3D-PTV method that incorporates time-resolved data. We detail the method, its performance in terms of particle identification and reconstruction error and their relation to varying seeding densities, as well as computational performance.

  5. Spectra-resolved technique of a sensitive time-resolved fluorescence immunoassay instrument

    Science.gov (United States)

    Guo, Zhouyi; Tian, Zhen; Jia, Yali

    2004-07-01

    The lanthanide trivalence ion and its chelates are used for marking substance in time-resolved fluorescence immunoassay (TRFIA), marking the protein, hormone, antibody, nucleic acid probe or biologica alive cell, to measure the concentration of the analysis substance inside the reaction system with time-resolved fluorometry after the reaction system occurred, and attain the quantitative analysis's purpose. TRFIA has been become a kind of new and more sensitive measure method after radioisotope marking, enzymatic marking, chemiluminescence, electrochemiluminescence, it primarily is decided by the special physics and chemistry characteristic of lanthanide trivalence ion and its chelates. In this paper, the result of spectroscopic evaluation of europium trivalence ion and its chelate, and the principle of spectra-resolved technology and a sensitive time-resolved fluorescence immunoassay instrument made by ourselves are reported. In the set, a high frequency Xenon pulsed-light was adopted as exciting light, and two special filters was utilized according to spectra-resolved technique. Thus the influence of scattering light and short-lifetime fluorescence was removed. And the sensitivity is 10-12mol/L (when Eu3+ was used for marking substance), examination repeat is CV = 95% (p < 0.01).

  6. The TimBel synchronization board for time resolved experiments at synchrotron SOLEIL

    International Nuclear Information System (INIS)

    Ricaud, J.P.; Betinelli-Deck, P.; Bisou, J.; Elattaoui, X.; Laulhe, C.; Monteiro, P.; Nadolski, L.S.; Renaud, G.; Ravy, S.; Silly, M.; Sirotti, F.

    2012-01-01

    Time resolved experiments are one of the major services that synchrotrons can provide to scientists. The short, high frequency and regular flashes of synchrotron light are a fantastic tool to study the evolution of phenomena over time. To carry out time resolved experiments, beamlines need to synchronize their devices with these flashes of light with a jitter shorter than the pulse duration. For that purpose, Synchrotron SOLEIL has developed the TimBeL (Timing Beamlines) board fully interfaced to TANGO framework. The TimBeL system is a compact PCI board. It is made of a mother with one daughter board. All functions are performed inside a FPGA (Field Programmable Gate Array) implemented on the mother board. A PLX Technology chip is used to communicate with the compact PCI crate. To enable experiments to remain always synchronous with the same bunch of electrons, the storage ring clock (CLK-SR) and the radio frequency clock (CLK-RF) are provided by the machine to beamlines. These clocks are used inside the FPGA as main clocks for state machines. Because the jitter is too large on the FPGA outputs, a daughter board with a jitter cleaner has been added to the system. This board also provides delay lines for compensating time offsets by 10 ps steps. This paper presents the main features required by time resolved experiments and how we achieved our goals with the TimBeL board

  7. Quantitative analysis of pulmonary perfusion using time-resolved parallel 3D MRI - initial results

    International Nuclear Information System (INIS)

    Fink, C.; Buhmann, R.; Plathow, C.; Puderbach, M.; Kauczor, H.U.; Risse, F.; Ley, S.; Meyer, F.J.

    2004-01-01

    Purpose: to assess the use of time-resolved parallel 3D MRI for a quantitative analysis of pulmonary perfusion in patients with cardiopulmonary disease. Materials and methods: eight patients with pulmonary embolism or pulmonary hypertension were examined with a time-resolved 3D gradient echo pulse sequence with parallel imaging techniques (FLASH 3D, TE/TR: 0.8/1.9 ms; flip angle: 40 ; GRAPPA). A quantitative perfusion analysis based on indicator dilution theory was performed using a dedicated software. Results: patients with pulmonary embolism or chronic thromboembolic pulmonary hypertension revealed characteristic wedge-shaped perfusion defects at perfusion MRI. They were characterized by a decreased pulmonary blood flow (PBF) and pulmonary blood volume (PBV) and increased mean transit time (MTT). Patients with primary pulmonary hypertension or eisenmenger syndrome showed a more homogeneous perfusion pattern. The mean MTT of all patients was 3.3 - 4.7 s. The mean PBF and PBV showed a broader interindividual variation (PBF: 104-322 ml/100 ml/min; PBV: 8 - 21 ml/100 ml). Conclusion: time-resolved parallel 3D MRI allows at least a semi-quantitative assessment of lung perfusion. Future studies will have to assess the clinical value of this quantitative information for the diagnosis and management of cardiopulmonary disease. (orig.) [de

  8. In situ and/or time resolved powder neutron scattering for materials science

    International Nuclear Information System (INIS)

    Isnard, O.

    2006-01-01

    In general, neutrons offer the advantage to be weakly absorbed by materials. Consequently neutron scattering is a very efficient tool to probe deeply inside the materials in a non destructive manner. Time resolved neutron scattering is thus widely used by different scientific fields: materials science, physics, chemistry, etc. It is now possible to perform neutron diffraction in situ, in complex environments: electrochemical reaction cells, pressure cells, etc. In situ neutron diffraction has been widely developed on high neutron flux sources such as those of the Institut Laue Langevin (Grenoble). Neutron scattering is a very useful technique for time resolved reaction processes inside materials. The experimental set-up needed for such type of experiments is briefly presented. Thereafter, examples of recent applications of neutron diffraction are described to illustrate the possible use of thermodiffractometry, in situ and/or time resolved to investigate phase transitions of chemical processes. The examples are taken in different scientific fields: metallurgy, electrochemistry, magnetism, solid state chemistry and archeometry. (author)

  9. Wake losses from averaged and time-resolved power measurements at full scale wind turbines

    Science.gov (United States)

    Castellani, Francesco; Astolfi, Davide; Mana, Matteo; Becchetti, Matteo; Segalini, Antonio

    2017-05-01

    This work deals with the experimental analysis of wake losses fluctuations at full-scale wind turbines. The test case is a wind farm sited on a moderately complex terrain: 4 turbines are installed, having 2 MW of rated power each. The sources of information are the time-resolved data, as collected from the OPC server, and the 10-minutes averaged SCADA data. The objective is to compare the statistical distributions of wake losses for far and middle wakes, as can be observed through the “fast” lens of time-resolved data, for certain selected test-case time series, and through the “slow” lens of SCADA data, on a much longer time basis that allow to set the standards of the mean wake losses along the wind farm. Further, time-resolved data are used for an insight into the spectral properties of wake fluctuations, highlighting the role of the wind turbine as low-pass filter. Summarizing, the wind rose, the layout of the site and the structure of the data sets at disposal allow to study middle and far wake behavior, with a “slow” and “fast” perspective.

  10. Time-resolved luminescence from quartz: An overview of contemporary developments and applications

    Science.gov (United States)

    Chithambo, M. L.; Ankjærgaard, C.; Pagonis, V.

    2016-01-01

    Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al2O3:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz-feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.

  11. Prospective time-resolved LCA of fully electric supercap vehicles in Germany.

    Science.gov (United States)

    Zimmermann, Benedikt M; Dura, Hanna; Baumann, Manuel J; Weil, Marcel R

    2015-07-01

    The ongoing transition of the German electricity supply toward a higher share of renewable and sustainable energy sources, called Energiewende in German, has led to dynamic changes in the environmental impact of electricity over the last few years. Prominent scenario studies predict that comparable dynamics will continue in the coming decades, which will further improve the environmental performance of Germany's electricity supply. Life cycle assessment (LCA) is the methodology commonly used to evaluate environmental performance. Previous LCA studies on electric vehicles have shown that the electricity supply for the vehicles' operation is responsible for the major part of their environmental impact. The core question of this study is how the prospective dynamic development of the German electricity mix will affect the impact of electric vehicles operated in Germany and how LCA can be adapted to analyze this impact in a more robust manner. The previously suggested approach of time-resolved LCA, which is located between static and dynamic LCA, is used in this study and compared with several static approaches. Furthermore, the uncertainty issue associated with scenario studies is addressed in general and in relation to time-resolved LCA. Two scenario studies relevant to policy making have been selected, but a moderate number of modifications have been necessary to adapt the data to the requirements of a life cycle inventory. A potential, fully electric vehicle powered by a supercapacitor energy storage system is used as a generic example. The results show that substantial improvements in the environmental repercussions of the electricity supply and, consequentially, of electric vehicles will be achieved between 2020 and 2031 on the basis of the energy mixes predicted in both studies. This study concludes that although scenarios might not be able to predict the future, they should nonetheless be used as data sources in prospective LCA studies, because in many cases

  12. Time-resolved methods in biophysics. 6. Time-resolved Laue crystallography as a tool to investigate photo-activated protein dynamics.

    Science.gov (United States)

    Bourgeois, Dominique; Schotte, Friedrich; Brunori, Maurizio; Vallone, Beatrice

    2007-10-01

    When polychromatic X-rays are shined onto crystalline material, they generate a Laue diffraction pattern. At third generation synchrotron radiation sources, a single X-ray pulse of approximately 100 ps duration is enough to produce interpretable Laue data from biomolecular crystals. Thus, by initiating biological turnover in a crystalline protein, structural changes along the reaction pathway may be filmed by ultra-fast Laue diffraction. Using laser-light as a trigger, transient species in photosensitive macromolecules can be captured at near atomic resolution with sub-nanosecond time-resolution. Such pump-probe Laue experiments have now reached an outstanding level of sophistication and have found a domain of excellence in the investigation of light-sensitive proteins undergoing cyclic photo-reactions and producing stiff crystals. The main theoretical concepts of Laue diffraction and the challenges associated with time-resolved experiments on biological crystals are recalled. The recent advances in the design of experiments are presented in terms of instrumental choices, data collection strategy and data processing, and some of the inherent difficulties of the method are highlighted. The discussion is based on the example of myoglobin, a protein that has traversed the whole history of pump-probe Laue diffraction, and for which a massive amount of data have provided considerable insight into the understanding of protein dynamics.

  13. Operational Circulars

    CERN Multimedia

    2003-01-01

    Operational Circular N° 4 - April 2003 Conditions for use by members of the CERN personnel of vehicles belonging to or rented by CERN - This circular has been drawn up. Operational Circular N° 5 - October 2000 Use of CERN computing facilities - Further details on the personal use of CERN computing facilities Operational Circular N° 5 and its Subsidiary Rules http://cern.ch/ComputingRules defines the rules for the use of CERN computing facilities. One of the basic principles governing such use is that it must come within the professional duties of the user concerned, as defined by the user's divisional hierarchy. However, personal use of the computing facilities is tolerated or allowed provided : a) It is in compliance with Operational Circular N° 5 and not detrimental to official duties, including those of other users; b) the frequency and duration is limited and there is a negligible use of CERN resources; c) it does not constitute a political, commercial and/or profit-making activity; d) it is not...

  14. A comparative study of interaction of tetracycline with several proteins using time resolved anisotropy, phosphorescence, docking and FRET.

    Directory of Open Access Journals (Sweden)

    Manini Mukherjee

    Full Text Available A comparative study of the interaction of an antibiotic Tetracycline hydrochloride (TC with two albumins, Human serum albumin (HSA and Bovine serum albumin (BSA along with Escherichia Coli Alkaline Phosphatase (AP has been presented exploiting the enhanced emission and anisotropy of the bound drug. The association constant at 298 K is found to be two orders of magnitude lower in BSA/HSA compared to that in AP with number of binding site being one in each case. Fluorescence resonance energy transfer (FRET and molecular docking studies have been employed for the systems containing HSA and BSA to find out the particular tryptophan (Trp residue and the other residues in the proteins involved in the binding process. Rotational correlation time (θc of the bound TC obtained from time resolved anisotropy of TC in all the protein-TC complexes has been compared to understand the binding mechanism. Low temperature (77 K phosphorescence (LTP spectra of Trp residues in the free proteins (HSA/BSA and in the complexes of HSA/BSA have been used to specify the role of Trp residues in FRET and in the binding process. The results have been compared with those obtained for the complex of AP with TC. The photophysical behaviour (viz., emission maximum, quantum yield, lifetime and θc of TC in various protic and aprotic polar solvents has been determined to address the nature of the microenvironment of TC in the protein-drug complexes.

  15. Identifiability analysis of rotational diffusion tensor and electronic transition moments measured in time-resolved fluorescence depolarization experiment

    International Nuclear Information System (INIS)

    Szubiakowski, Jacek P.

    2014-01-01

    The subject of this paper is studies of the deterministic identifiability of molecular parameters, such as rotational diffusion tensor components and orientation of electronic transition moments, resulting from the time-resolved fluorescence anisotropy experiment. In the most general case considered, a pair of perpendicularly polarized emissions enables the unique determination of all the rotational diffusion tensor's principal components. The influence of the tensor's symmetry and the associated degeneration of its eigenvalues on the identifiability of the electronic transitions moments is systematically investigated. The analysis reveals that independently of the rotational diffusion tensor's symmetry, the transition moments involved in photoselection and emission processes cannot be uniquely identified without a priori information about their mutual orientation or their orientation with respect to the principal axes of the tensor. Moreover, it is shown that increasing the symmetry of the rotational diffusion tensor deteriorates the degree of the transition moments identifiability. To obtain these results analytically, a novel approach to solve bilinear system of equations for Markov parameters is applied. The effect of the additional information, obtained from fluorescence measurements for different molecular mobilities, to improve the identifiability at various levels of analysis is shown. The effectiveness and reliability of the target analysis method for experimental determination of the molecular parameters is also discussed

  16. Time-resolved beam symmetry measurement for VMAT commissioning and quality assurance.

    Science.gov (United States)

    Barnes, Michael P; Greer, Peter B

    2016-03-08

    In volumetric-modulated arc therapy (VMAT) treatment delivery perfect beam symmetry is assumed by the planning system. This study aims to test this assumption and present a method of measuring time-resolved beam symmetry measurement during a VMAT delivery that includes extreme variations of dose rate and gantry speed. The Sun Nuclear IC Profiler in gantry mount was used to measure time-resolved in-plane and cross-plane profiles during plan delivery from which symmetry could be determined. Time-resolved symmetry measurements were performed throughout static field exposures at cardinal gantry angles, conformal arcs with constant dose rate and gantry speed, and during a VMAT test plan with gantry speed and dose rate modulation. Measurements were performed for both clockwise and counterclockwise gantry rotation and across four Varian 21iX lin-acs. The symmetry was found to be generally constant throughout the static field exposures to within 0.3% with an exception on one linac of up to 0.7%. Agreement in symmetry between cardinal angles was always within 1.0% and typically within 0.6%. During conformal arcs the results for clockwise and counterclockwise rotation were in agreement to within 0.3%. Both clockwise and counterclockwise tended to vary in similar manner by up to 0.5% during arc consistent with the cardinal gantry angle static field results. During the VMAT test plan the symmetry generally was in agreement with the conformal arc results. Greater variation in symmetry was observed in the low-dose-rate regions by up to 1.75%. All results were within clinically acceptable levels using the tolerances of NCS Report 24 (2015).

  17. Ultrafast time-resolved spectroscopy of white-light continuum by optical Kerr grating

    Science.gov (United States)

    Wang, Yusu; Sui, Laizhi; Jiang, Yuanfei; Liu, Dunli; Li, Qingyi; Chen, Anmin; Jin, Mingxing

    2017-05-01

    We have optimized a femtosecond time-resolved system by the optical Kerr-gate (OKG) method to investigate characteristics of various Kerr media. Optical Kerr gating is widely used in ultrafast measurements ranging from pulse characterization to spectroscopy and microscopy. We compared the efficiencies and the temporal responses of three Kerr media CS2, benzene and GGG. We have demonstrated that benzene has fast response and low efficiency while CS2 has high efficiency and slow response. Benzene as a Kerr medium shows the most befitting characteristics in the three media.

  18. Atomic motion of resonantly vibrating quartz crystal visualized by time-resolved X-ray diffraction

    International Nuclear Information System (INIS)

    Aoyagi, Shinobu; Osawa, Hitoshi; Sugimoto, Kunihisa; Fujiwara, Akihiko; Takeda, Shoichi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro

    2015-01-01

    Transient atomic displacements during a resonant thickness-shear vibration of AT-cut α-quartz are revealed by time-resolved X-ray diffraction under an alternating electric field. The lattice strain resonantly amplified by the alternating electric field is ∼10 4 times larger than that induced by a static electric field. The resonantly amplified lattice strain is achieved by fast displacements of oxygen anions and collateral resilient deformation of Si−O−Si angles bridging rigid SiO 4 tetrahedra, which efficiently transduce electric energy into elastic energy

  19. Time-resolved ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer

    Science.gov (United States)

    Yang, Qing; Zhou, Xiaohong; Nukui, Takao; Saeki, Yu; Izumi, Sotaro; Tackeuchi, Atsushi; Tatsuoka, Hirokazu; Liang, Shuhua

    2014-02-01

    The ultraviolet photoluminescence of ZnO/ZnGa2O4 composite layer grown by the thermal oxidation of ZnS with gallium was investigated by the time-resolved photoluminescence as a function of measuring temperature and excitation power. With increase of excitation power, the D0X emission is easily saturated than the DAP emission from ZnO/ZnGa2O4 composite layer, and which is dramatically enhanced as compared with that from pure ZnO layer grown without gallium. The radiative recombination process with ultra-long lifetime controlled the carrier recombination of ZnO/ZnGa2O4 composite layer.

  20. First photon detection in time-resolved transillumination imaging: a theoretical evaluation

    International Nuclear Information System (INIS)

    Behin-Ain, S; Doorn, T van; Patterson, J R

    2004-01-01

    First photon detection, as a special case of time-resolved transillumination imaging, is studied through the derivation of the temporal probability density function (pdf) for the first arriving photon. The pdf for different laser intensities, media and second and later arriving photons were generated. The arrival time of the first detected photon reduced as the laser power increased and also when the scattering and absorption coefficients decreased. The pdf for an imbedded totally absorbing 3 mm inhomogeneity may be distinguished from the pdf of a homogeneous turbid medium similar to that of human breast in dimensions and optical properties

  1. Full-field pressure from snapshot and time-resolved volumetric PIV

    OpenAIRE

    Laskari, Angeliki; de Kat, Roeland; Ganapathisubramani, Bharathram

    2016-01-01

    This paper deals with pressure estimation from snapshot and time-resolved three-component (3C) volumetric PIV data using Taylor’s hypothesis, an Eulerian and a pseudo-Lagrangian approach. The Taylor’s hypothesis approach has been shown to provide accurate results for pressure in the case of 3C planar PIV data with an appropriate choice of convection velocity (de Kat and Ganapathisubramani 2013), and here we extend its use on 3C volumetric velocity snapshots. Application of the techniques to s...

  2. Hole emission from Ge/Si quantum dots studied by time-resolved capacitance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kapteyn, C.M.A.; Lion, M.; Heitz, R.; Bimberg, D. [Technische Univ. Berlin (Germany). Inst. fuer Festkoerperphysik; Miesner, C.; Asperger, T.; Brunner, K.; Abstreiter, G. [Technische Univ. Muenchen, Garching (Germany). Walter-Schottky-Inst. fuer Physikalische Grundlagen der Halbleiterelektronik

    2001-03-01

    Emission of holes from self-organized Ge quantum dots (QDs) embedded in Si Schottky diodes is studied by time-resolved capacitance spectroscopy (DLTS). The DLTS signal is rather broad and depends strongly on the filling and detection bias conditions. The observed dependence is interpreted in terms of carrier emission from many-hole states of the QDs. The activation energies obtained from the DLTS measurements are a function of the amount of stored charge and the position of the Fermi level in the QDs. (orig.)

  3. Time-resolved terahertz spectroscopy of conjugated polymer/CdSe nanorod composites

    DEFF Research Database (Denmark)

    Cooke, David; Lek, Jun Y.; Krebs, Frederik C

    2010-01-01

    report ultrafast carrier dynamics in hybrid CdSe nanorod / poly(3-hexythiophene) (P3HT) bulk heterojunction films measured by time-resolved terahertz spectroscopy, and compare to the well studied P3HT/phenyl-C61-butyric acid methyl ester (PCBM) blend. Both films show an improved peak...... photoconductivity compared to P3HT alone, consistent with efficient charge transfer. The photoconductivity dynamics show fast, picosecond trapping or recombination in the hybrid blend while the all-organic film shows no such loss of mobile charge over ns time scales. The ac conductivity for all samples is well...

  4. Time-Resolved Macromolecular Crystallography at Modern X-Ray Sources.

    Science.gov (United States)

    Schmidt, Marius

    2017-01-01

    Time-resolved macromolecular crystallography unifies protein structure determination with chemical kinetics. With the advent of fourth generation X-ray sources the time-resolution can be on the order of 10-40 fs, which opens the ultrafast time scale to structure determination. Fundamental motions and transitions associated with chemical reactions in proteins can now be observed. Moreover, new experimental approaches at synchrotrons allow for the straightforward investigation of all kind of reactions in biological macromolecules. Here, recent developments in the field are reviewed.

  5. Studying the potential of point detectors in time-resolved dose verification of dynamic radiotherapy

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Behrens, C. F.; Andersen, Claus E.

    2015-01-01

    based on fiber-coupled plastic scintillator detectors was evaluated and compared with a Farmer-type ionization chamber and a small-volume ionization chamber. An important feature of scintillator detectors is that the sensitive volume of the detector can easily be scaled, and five scintillator detectors......-volume ionization chamber and the smallest scintillators. The time-resolved RapidArc dose profiles revealed volume-dependent discrepancies between scintillator and ionization chamber response, which confirmed that correction factors for ionization chambers in high temporal and spatial dose gradients are dominated...

  6. Time-resolved angular distributions of plume ions from silver at low and medium laser fluence

    DEFF Research Database (Denmark)

    Christensen, Bo Toftmann; Schou, Jørgen

    Even at moderate fluence (0.6 -2.4 J/cm2) laser impact on metals in the UV regime results in a significant number of ions emitted from the surface. The ablated particles are largely neutrals at the lowest fluence, but the fraction of ions increases strongly with fluence. We have irradiated silver...... in a vacuum chamber (~ 10-7 mbar) with a Nd:YAG laser at a wavelength of 355 nm and made detailed measurements of the time-resolved angular distribution. The ion flow in different directions has been measured with a hemispherical array of Langmuir probes, by which the time-of-flight spectra, as well...

  7. Time Resolved Digital PIV Measurements of Flow Field Cyclic Variation in an Optical IC Engine

    International Nuclear Information System (INIS)

    Jarvis, S; Justham, T; Clarke, A; Garner, C P; Hargrave, G K; Halliwell, N A

    2006-01-01

    Time resolved digital particle image velocimetry (DPIV) experimental data is presented for the in-cylinder flow field development of a motored four stroke spark ignition (SI) optical internal combustion (IC) engine. A high speed DPIV system was employed to quantify the velocity field development during the intake and compression stroke at an engine speed of 1500 rpm. The results map the spatial and temporal development of the in-cylinder flow field structure allowing comparison between traditional ensemble average and cycle average flow field structures. Conclusions are drawn with respect to engine flow field cyclic variations

  8. Time resolved temperature measurement of polymer surface irradiated by mid-IR free electron laser

    Science.gov (United States)

    Araki, Mitsunori; Chiba, Tomoyuki; Oyama, Takahiro; Imai, Takayuki; Tsukiyama, Koichi

    2017-08-01

    We have developed the time-resolved temperature measurement system by using a radiation thermometer FLIR SC620. Temporal temperature profiles of an acrylic resin surface by the irradiation of infrared free electron laser (FEL) pulse were recorded in an 8 ms resolution to measure an instantaneous temperature rise and decay profile. Under the single-shot condition, a peak temperature defined as the temperature jump from the ambient temperature was found to be proportional to the absorbance. Under the multi-shot condition, the temperature accumulation was found to reach a roughly constant value where the supply and release of the heat is balanced.

  9. Time-resolved plastic scintillator dosimetry in a dynamic thorax phantom

    DEFF Research Database (Denmark)

    Sibolt, Patrik; Andersen, Claus E.; Ottosson, Wiviann

    2017-01-01

    in a lung. The phantom motion was controlled by a script in-house developed using LabVIEW (National Instruments) and synchronized with the in-house developed ME40 scintillator dosimetry system (DTU Nutech). The dose in the center of the tumor was measured, using a BCF-60 plastic scintillator detector (Saint...... respiratory motion and lack of lateral charged particle equilibrium, motivating quality assurance based on a system like the one presented in this study. It has specifically been demonstrated that reliable time-resolved scintillator dosimetry in a dynamic thorax phantom can play an essential role in dose...

  10. Photoemission with high-order harmonics: A tool for time-resolved core-level spectroscopy

    DEFF Research Database (Denmark)

    Christensen, Bjarke Holl; Raarup, Merete Krog; Balling, Peter

    2010-01-01

    A setup for femtosecond time-resolved photoelectron spectroscopy of solid surfaces is presented. The photon energies for core-level spectroscopy experiments are created by high-order harmonic generation from infrared 120-femtosecond laser pulses focused in a Ne gas jet. The present experimental r...... from the sample are collected by a large-solid-angle time-of-flight electron spectrometer based on a parabolic-grid reflector. Results from experiments probing the Bi 5d core-levels are presented, and the results of preliminary pump-probe experiments are described....

  11. Watching proteins function with time-resolved x-ray crystallography

    Energy Technology Data Exchange (ETDEWEB)

    Šrajer, Vukica; Schmidt, Marius

    2017-08-22

    Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115–54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201–41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651–9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237–51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5–20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242–6, Barends et al 2015 Science 350 445–50, Pande et al 2016 Science 352 725–9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We

  12. Watching proteins function with time-resolved x-ray crystallography

    Science.gov (United States)

    Šrajer, Vukica; Schmidt, Marius

    2017-09-01

    Macromolecular crystallography was immensely successful in the last two decades. To a large degree this success resulted from use of powerful third generation synchrotron x-ray sources. An expansive database of more than 100 000 protein structures, of which many were determined at resolution better than 2 Å, is available today. With this achievement, the spotlight in structural biology is shifting from determination of static structures to elucidating dynamic aspects of protein function. A powerful tool for addressing these aspects is time-resolved crystallography, where a genuine biological function is triggered in the crystal with a goal of capturing molecules in action and determining protein kinetics and structures of intermediates (Schmidt et al 2005a Methods Mol. Biol. 305 115-54, Schmidt 2008 Ultrashort Laser Pulses in Biology and Medicine (Berlin: Springer) pp 201-41, Neutze and Moffat 2012 Curr. Opin. Struct. Biol. 22 651-9, Šrajer 2014 The Future of Dynamic Structural Science (Berlin: Springer) pp 237-51). In this approach, short and intense x-ray pulses are used to probe intermediates in real time and at room temperature, in an ongoing reaction that is initiated synchronously and rapidly in the crystal. Time-resolved macromolecular crystallography with 100 ps time resolution at synchrotron x-ray sources is in its mature phase today, particularly for studies of reversible, light-initiated reactions. The advent of the new free electron lasers for hard x-rays (XFELs; 5-20 keV), which provide exceptionally intense, femtosecond x-ray pulses, marks a new frontier for time-resolved crystallography. The exploration of ultra-fast events becomes possible in high-resolution structural detail, on sub-picosecond time scales (Tenboer et al 2014 Science 346 1242-6, Barends et al 2015 Science 350 445-50, Pande et al 2016 Science 352 725-9). We review here state-of-the-art time-resolved crystallographic experiments both at synchrotrons and XFELs. We also outline

  13. Time resolved IR-LIGS experiments for gas-phase trace detection and temperature measurements

    Energy Technology Data Exchange (ETDEWEB)

    Fantoni, R.; Giorgi, M. [ENEA, Centro Ricerche Frascati, Rome (Italy). Dip. Innovazione; Snels, M. [CNR, Tito Scalo, Potenza (Italy). Istituto per i Materiali Speciali; Latzel, H.

    1997-01-01

    Time resolved Laser Induced Grating Spectroscopy (LIGS) has been performed to detect different gases in mixtures at atmospheric pressure or higher. The possibility of trace detection of minor species and of temperature measurements has been demonstrated for various molecular species either of environmental interest or involved in combustion processes. In view of the application of tracing unburned hydrocarbons in combustion chambers, the coupling of the IR-LIGS technique with imaging detection has been considered and preliminary results obtained in small size ethylene/air flames are shown.

  14. Time-resolved SAXS measurements facilitated by online HPLC buffer exchange

    DEFF Research Database (Denmark)

    Jensen, Malene Hillerup; Toft, Katrine Nørgaard; David, Gabriel

    2010-01-01

    be possible to separate contributions from individual species present in solution. Hence, time-resolved SAXS (TR-SAXS) data of processes in development can be analyzed. Many reported TR-SAXS results are initialized by a sudden change in buffer conditions facilitated by rapid mixing combined with either...... continuous or stopped flow. In this paper a method for obtaining TR-SAXS data from systems where the reaction is triggered by removal of a species is presented. This method is based on fast buffer exchange over a short desalting column facilitated by an online HPLC (high-performance liquid chromatography...

  15. Optical Coherence Tomography (OCT for Time-Resolved Imaging of Alveolar Dynamics in Mechanically Ventilated Rats

    Directory of Open Access Journals (Sweden)

    Christian Schnabel

    2017-03-01

    Full Text Available Though artificial ventilation is an essential life-saving treatment, the mechanical behavior of lung tissue at the alveolar level is still unknown. Therefore, we need to understand the tissue response during artificial ventilation at this microscale in order to develop new and more protective ventilation methods. Optical coherence tomography (OCT combined with intravital microscopy (IVM is a promising tool for visualizing lung tissue dynamics with a high spatial and temporal resolution in uninterruptedly ventilated rats. We present a measurement setup using a custom-made animal ventilator and a gating technique for data acquisition of time-resolved sequences.

  16. A sensitive time-resolved radiation pyrometer for shock-temperature measurements above 1500 K

    Science.gov (United States)

    Boslough, Mark B.; Ahrens, Thomas J.

    1989-01-01

    The general design, calibration, and performance of a new high-sensitivity radiation pyrometer are described. The pyrometer can determine time-resolved temperatures (as low as 1500 K) in shocked materials by measuring the spectral radiance of light emitted from shocked solid samples in the visible and near-infrared wavelength range (0.5-1.0 micron). The high sensitivity of the radiation pyrometer is attributed to the large angular aperture (0.06 sr), the large bandwidth per channel (up to 0.1 micron), the large photodiode detection areas (1.0 sq cm), and the small number of calibrated channels (4) among which light is divided.

  17. Time-resolved protein dynamics using synchronized Ti sapphire regenerative amplifier/infrared FEL

    Energy Technology Data Exchange (ETDEWEB)

    Stanley, R.J.; Haar, P.; Boxer, S.G. [Stanford Univ., CA (United States)

    1995-12-31

    We have synchronized a femtosecond 5 kHz Ti Sapphire regenerative amplifier (regen) to the Stanford Superconducting Accelerator/Free Electron laser (SCA/FEL) to within 2 picoseconds time jitter. We are using this capability to measure the time resolved spectral evolution of the radical cation band of the initial electron donor from bacterial reaction centers (Rb sphaeroides) after the initiation of electron transfer using a {approximately} 120 fs NIR pulse from the regen. The FEL is used to probe for the appearance of the radical cation band at {approximately} 4 {mu}m.

  18. Performance of the Time Resolved Spectrometer for the 5 MeV Photo-Injector PHIN

    CERN Document Server

    Olvegaard, M; Mete, O; Csatari, M; Dabrowski, A; Dobert, S; Lefevre, T; Petrarca, M

    2011-01-01

    The PHIN photo-injector test facility is being commissioned at CERN to demonstrate the capability to produce the required beam for the 3rd CLIC Test Facility (CTF3), which includes the production of a 3.5A stable beam, bunched at 1.5 GHz with a relative energy spread of less than 1%. A 90◦ spectrometer is instrumented with an OTR screen coupled to a gated intensified camera, followed by a segmented beam dump for time resolved energy measurements. The following paper describes the transverse and temporal resolution of the instrumentation with an outlook towards single-bunch energy measurements.

  19. Ultrafast time-resolved faraday rotation in EuO thin films.

    Science.gov (United States)

    Liu, F; Makino, T; Yamasaki, T; Ueno, K; Tsukazaki, A; Fukumura, T; Kong, Y; Kawasaki, M

    2012-06-22

    We have investigated the ultrafast spin dynamics in EuO thin films by time-resolved Faraday rotation spectroscopy. The photoinduced magnetization is found to be increased in a transient manner, accompanied with subsequent demagnetization. The dynamical magnetization enhancement showed a maximum slightly below the Curie temperature with prolonged tails toward both lower and higher temperatures and dominates the demagnetization counterpart at 55 K. The magnetization enhancement component decays in ~1 ns. The realization of the transient collective ordering is attributable to the enhancement of the f-d exchange interaction.

  20. Measurements of Turbulent Convection Speeds in Multistream Jets Using Time-Resolved PIV

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2017-01-01

    Convection speeds of turbulent velocities in jets, including multi-stream jets with and without flight stream, were measured using an innovative application of time-resolved particle image velocimetry. The paper describes the unique instrumentation and data analysis that allows the measurement to be made. Extensive data is shown that relates convection speed, mean velocity, and turbulent velocities for multiple jet cases. These data support the overall observation that the local turbulent convection speed is roughly that of the local mean velocity, biased by the relative intensity of turbulence.

  1. Measurements of Turbulence Convection Speeds in Multistream Jets Using Time-Resolved PIV

    Science.gov (United States)

    Bridges, James; Wernet, Mark P.

    2017-01-01

    Convection speeds of turbulent velocities in jets, including multi-stream jets with and without flight stream, were measured using an innovative application of time-resolved particle image velocimetry. The paper describes the unique instrumentation and data analysis that allows the measurement to be made. Extensive data is shown that relates convection speed, mean velocity, and turbulent velocities for multiple jet cases. These data support the overall observation that the local turbulent convection speed is roughly that of the local mean velocity, biased by the relative intensity of turbulence.

  2. Time-resolved Particle Image Velocimetry measurements of the 3D random Richtmyer-Meshkov Instability

    Science.gov (United States)

    Sewell, Everest; Krivets, Vitaliy; Jacobs, Jeffrey

    2017-11-01

    The vertical shock tube at the University of Arizona is used to perform experiments on the multi-mode three-dimensional Richtmyer-Meshkov Instability (RMI). An interface of air and sulfur hexafluoride is formed in a counter flow configuration, and is excited using voice coils to produce faraday-like multi-modal perturbations.This interface is shock accelerated by an approximately Mach 1.2 shockwave to form the RMI. Time resolved Particle Image Velocimetry (PIV) is used to perform analysis of the evolving instability.

  3. CMOS Time-Resolved, Contact, and Multispectral Fluorescence Imaging for DNA Molecular Diagnostics

    Directory of Open Access Journals (Sweden)

    Nan Guo

    2014-10-01

    Full Text Available Instrumental limitations such as bulkiness and high cost prevent the fluorescence technique from becoming ubiquitous for point-of-care deoxyribonucleic acid (DNA detection and other in-field molecular diagnostics applications. The complimentary metal-oxide-semiconductor (CMOS technology, as benefited from process scaling, provides several advanced capabilities such as high integration density, high-resolution signal processing, and low power consumption, enabling sensitive, integrated, and low-cost fluorescence analytical platforms. In this paper, CMOS time-resolved, contact, and multispectral imaging are reviewed. Recently reported CMOS fluorescence analysis microsystem prototypes are surveyed to highlight the present state of the art.

  4. Subcycle interference dynamics of time-resolved photoelectron holography with midinfrared laser pulses

    International Nuclear Information System (INIS)

    Bian Xuebin; Yuan, Kai-Jun; Bandrauk, Andre D.; Huismans, Y.; Smirnova, O.; Vrakking, M. J. J.

    2011-01-01

    Time-resolved photoelectron holography from atoms using midinfrared laser pulses is investigated by solving the corresponding time-dependent Schroedinger equation (TDSE) and a classical model, respectively. The numerical simulation of the photoelectron angular distribution of Xe irradiated with a low-frequency free-electron laser source agrees well with the experimental results. Different types of subcycle interferometric structures are predicted by the classical model. Furthermore with the TDSE model it is demonstrated that the holographic pattern is sensitive to the shape of the atomic orbitals. This is a step toward imaging by means of photoelectron holography.

  5. Intra-molecular mobility of charge carriers along oligogermane backbones studied by flash photolysis time-resolved microwave conductivity and transient optical spectroscopy techniques

    Energy Technology Data Exchange (ETDEWEB)

    Seki, Shu [Division of Applied Chemistry, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871 (Japan)], E-mail: seki@chem.eng.osaka-u.ac.jp; Saeki, Akinori; Acharya, Anjali; Koizumi, Yoshiko; Tagawa, Seiichi [The Institute of Scientific and Industrial Research, Osaka University, 8-1, Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Mochida, Kunio [Department of Chemistry Faculty of Science, Gakusyuin University, 1-5-1 Mejiro, Tokyo 171-8588 (Japan)

    2008-10-15

    Time-resolved microwave conductivity (TRMC) measurement has been performed for fullerene-doped thin films of oligo (dimethylgermane) at different excitation energies to evaluate the intra-molecular mobility of holes along their Ge backbones. Photo-induced electron transfer reaction between oligogermane and fullerene has been observed in the solution with a variety of solvent polarity using transient optical spectroscopy (TOS). The transient spectrum at 391 nm can be attributed to the radical cation of the oligomer under an excitation at 532-nm light, whereas the same spectrum (391 nm) is the overlapping of absorptions of radical cations and neutral radicals of oligogermanes upon exposure of 355-nm light in polar solvent. A combined TRMC and TOS experiments on the solutions of oligomer confirms the conductive transients originate from the radical cations on the backbone chains.

  6. Information circulars

    International Nuclear Information System (INIS)

    1989-04-01

    The document summarizes the Information Circulars published by the IAEA under the symbol INFCIRC/ for the purpose of bringing matters of general interest to the attention of all Members of the Agency. A complete list of INFCIRCs in numerical order with their titles is given in the Annex

  7. Time-resolved fluorescence studies of nucleotide flipping by restriction enzymes

    Science.gov (United States)

    Neely, Robert K.; Tamulaitis, Gintautas; Chen, Kai; Kubala, Marta; Siksnys, Virginijus; Jones, Anita C.

    2009-01-01

    Restriction enzymes Ecl18kI, PspGI and EcoRII-C, specific for interrupted 5-bp target sequences, flip the central base pair of these sequences into their protein pockets to facilitate sequence recognition and adjust the DNA cleavage pattern. We have used time-resolved fluorescence spectroscopy of 2-aminopurine-labelled DNA in complex with each of these enzymes in solution to explore the nucleotide flipping mechanism and to obtain a detailed picture of the molecular environment of the extrahelical bases. We also report the first study of the 7-bp cutter, PfoI, whose recognition sequence (T/CCNGGA) overlaps with that of the Ecl18kI-type enzymes, and for which the crystal structure is unknown. The time-resolved fluorescence experiments reveal that PfoI also uses base flipping as part of its DNA recognition mechanism and that the extrahelical bases are captured by PfoI in binding pockets whose structures are quite different to those of the structurally characterized enzymes Ecl18kI, PspGI and EcoRII-C. The fluorescence decay parameters of all the enzyme-DNA complexes are interpreted to provide insight into the mechanisms used by these four restriction enzymes to flip and recognize bases and the relationship between nucleotide flipping and DNA cleavage. PMID:19740769

  8. Compressive hyperspectral time-resolved wide-field fluorescence lifetime imaging

    Science.gov (United States)

    Pian, Qi; Yao, Ruoyang; Sinsuebphon, Nattawut; Intes, Xavier

    2017-07-01

    Spectrally resolved fluorescence lifetime imaging and spatial multiplexing have offered information content and collection-efficiency boosts in microscopy, but efficient implementations for macroscopic applications are still lacking. An imaging platform based on time-resolved structured light and hyperspectral single-pixel detection has been developed to perform quantitative macroscopic fluorescence lifetime imaging (MFLI) over a large field of view (FOV) and multiple spectral bands simultaneously. The system makes use of three digital micromirror device (DMD)-based spatial light modulators (SLMs) to generate spatial optical bases and reconstruct N by N images over 16 spectral channels with a time-resolved capability (∼40 ps temporal resolution) using fewer than N2 optical measurements. We demonstrate the potential of this new imaging platform by quantitatively imaging near-infrared (NIR) Förster resonance energy transfer (FRET) both in vitro and in vivo. The technique is well suited for quantitative hyperspectral lifetime imaging with a high sensitivity and paves the way for many important biomedical applications.

  9. Time resolved dosimetry of human brain exposed to low frequency pulsed magnetic fields

    Science.gov (United States)

    Paffi, Alessandra; Camera, Francesca; Lucano, Elena; Apollonio, Francesca; Liberti, Micaela

    2016-06-01

    An accurate dosimetry is a key issue to understanding brain stimulation and related interaction mechanisms with neuronal tissues at the basis of the increasing amount of literature revealing the effects on human brain induced by low-level, low frequency pulsed magnetic fields (PMFs). Most literature on brain dosimetry estimates the maximum E field value reached inside the tissue without considering its time pattern or tissue dispersivity. Nevertheless a time-resolved dosimetry, accounting for dispersive tissues behavior, becomes necessary considering that the threshold for an effect onset may vary depending on the pulse waveform and that tissues may filter the applied stimulatory fields altering the predicted stimulatory waveform’s size and shape. In this paper a time-resolved dosimetry has been applied on a realistic brain model exposed to the signal presented in Capone et al (2009 J. Neural Transm. 116 257-65), accounting for the broadband dispersivity of brain tissues up to several kHz, to accurately reconstruct electric field and current density waveforms inside different brain tissues. The results obtained by exposing the Duke’s brain model to this PMF signal show that the E peak in the brain is considerably underestimated if a simple monochromatic dosimetry is carried out at the pulse repetition frequency of 75 Hz.

  10. Ultrafast Time-Resolved Hard X-Ray Emission Spectroscopy on a Tabletop

    Directory of Open Access Journals (Sweden)

    Luis Miaja-Avila

    2016-09-01

    Full Text Available Experimental tools capable of monitoring both atomic and electronic structure on ultrafast (femtosecond to picosecond time scales are needed for investigating photophysical processes fundamental to light harvesting, photocatalysis, energy and data storage, and optical display technologies. Time-resolved hard x-ray (>3  keV spectroscopies have proven valuable for these measurements due to their elemental specificity and sensitivity to geometric and electronic structures. Here, we present the first tabletop apparatus capable of performing time-resolved x-ray emission spectroscopy. The time resolution of the apparatus is better than 6 ps. By combining a compact laser-driven plasma source with a highly efficient array of microcalorimeter x-ray detectors, we are able to observe photoinduced spin changes in an archetypal polypyridyl iron complex [Fe(2,2^{′}-bipyridine_{3}]^{2+} and accurately measure the lifetime of the quintet spin state. Our results demonstrate that ultrafast hard x-ray emission spectroscopy is no longer confined to large facilities and now can be performed in conventional laboratories with 10 times better time resolution than at synchrotrons. Our results are enabled, in part, by a 100- to 1000-fold increase in x-ray collection efficiency compared to current techniques.

  11. Characterization of female breast lesions from multi-wavelength time-resolved optical mammography

    International Nuclear Information System (INIS)

    Spinelli, Lorenzo; Torricelli, Alessandro; Pifferi, Antonio; Taroni, Paola; Danesini, Gianmaria; Cubeddu, Rinaldo

    2005-01-01

    Characterization of both malignant and benign lesions in the female breast is presented as the result of a clinical study that involved more than 190 subjects in the framework of the OPTIMAMM European project. All the subjects underwent optical mammography, by means of a multi-wavelength time-resolved mammograph, in the range 637-985 nm. Optical images were processed by applying a perturbation model, relying on a nonlinear approximation of time-resolved transmittance curves in the presence of an inclusion, with the aim of estimating the major tissue constituents (i.e. oxy- and deoxy-haemoglobin, lipid and water) and structural parameters (linked to dimension and density of the scatterer centres) for both the lesion area and the surrounding tissue. The critical factors for the application of the perturbation model on in vivo data are also discussed. Forty-six malignant and 68 benign lesions were analysed. A subset of 32 cancers, 40 cysts and 14 fibroadenomas were found reliable for the perturbation analysis. For cancers, we show a higher blood content with respect to the surrounding tissue, while cysts are characterized by a lower concentration of scattering centres with respect to the surrounding tissue. For fibroadenomas, the low number of cases does not allow any definite conclusions

  12. Time-resolved emission spectroscopy for the combustion analysis of series production engines

    Science.gov (United States)

    Block, Bernd; Moeser, Petra; Hentschel, Werner

    1997-04-01

    This paper presents a device that detects light emerging from the combustion inside a series production automotive engine. Simultaneous time and wavelength resolution is achieved by this system and it can be applied in a simple manner to either diesel or spark ignition (SI) engines without any geometrical modification or the combustion chamber. An optical probe is inserted into spark plug or glow plug. A fiber is connected to the probe and leads the light to a spectrograph, which provides spectral analysis in the UV and visible wavelength ranges. An intensified streak camera with time resolution in the microsecond range completes the detection unit. This measuring system enables time-resolved emission spectroscopy applied to the light emitted during the combustion in a series production engine. Time-resolved emission spectra are presented from both a diesel and an SI engine. The time behavior of the internal temperature in a diesel engine combustion chamber and its dependence on engine speed and load are measured with this setup using a multiple two-color method. In an SI engine, the time behavior of the emissions of specific molecules or radicals is detected. Thus, differences in the combustion process are demonstrated to be caused by operation with different fuels.

  13. Time-resolved near-infrared technique for bedside monitoring of absolute cerebral blood flow

    Science.gov (United States)

    Diop, Mamadou; Tichauer, Kenneth M.; Elliott, Jonathan T.; Migueis, Mark; Lee, Ting-Yim; St. Lawrence, Keith

    2010-02-01

    A primary focus of neurointensive care is monitoring the injured brain to detect harmful events that can impair cerebral blood flow (CBF). Since current non-invasive bedside methods can only indirectly assess blood flow, the goal of this research was to develop an optical technique for measuring absolute CBF. A time-resolved near-infrared (NIR) apparatus was built and its ability to accurately measure changes in optical properties was demonstrated in tissue-mimicking phantoms. The time-resolved system was combined with a bolus-tracking method for measuring CBF using the dye indocyanine green (ICG) as an intravascular flow tracer. Cerebral blood flow was measured in newborn piglets and for comparison, CBF was concurrently measured using a previously developed continuous-wave NIR method. Measurements were acquired with both techniques under three conditions: normocapnia, hypercapnia and following occlusion of the carotid arteries. Mean CBF values (N = 3) acquired with the TR-NIR system were 31.9 +/- 11.7 ml/100g/min during occlusion, 39.7 +/- 1.6 ml/100g/min at normocapnia, and 58.8 +/- 9.9 ml/100g/min at hypercapnia. Results demonstrate that the developed TR-NIR technique has the sensitivity to measure changes in CBF; however, the CBF measurements were approximately 25% lower than the values obtained with the CW-NIRS technique.

  14. Multi-Channel Amplifier-Discriminator for Highly Time-Resolved Detection

    CERN Document Server

    Despeisse, M; Lapington, J; Jarron, P

    2011-01-01

    A low-power multi-channel amplifier-discriminator was developed for application in highly time-resolved detection systems. The proposed circuit architecture, so-called Nino, is based on a time-over-threshold approach and shows a high potential for time-resolved readout of solid-state photo-detectors and of detectors based on vacuum technologies. The Irpics circuit was designed in a 250 nm CMOS technology, implementing 32 channels of a Nino version optimized to achieve high-time resolution on the output low-voltage differential signals (LVDS) while keeping a low power consumption of 10 mW per channel. Electrical characterizations of the circuit demonstrate a very low intrinsic time jitter on the output pulse leading edge, measured below 10 ps rms for each channel for high input signal charges (100 fC) and below 25 ps rms for low input signal charges (20-100 fC). The read-out architecture moreover permits to retrieve the input signal charge from the timing measurements, while a calibration procedure was develop...

  15. Time-resolved method to distinguish protein/peptide oxidation during electrospray ionization mass spectrometry.

    Science.gov (United States)

    Pei, Jiying; Hsu, Cheng-Chih; Yu, Kefu; Wang, Yinghui; Huang, Guangming

    2018-06-29

    Electrospray ionization mass spectrometry (ESI-MS) is one of the most prevalent techniques used to monitor protein/peptide oxidation induced by reactive oxygen species (ROSs). However, both corona discharge (CD) and electrochemistry (EC) can also lead to protein/peptide oxidation during ESI. Because the two types of oxidation occur almost simultaneously, determining the extent to which the two pathways contribute to protein/peptide oxidation is difficult. Herein, a time-resolved method was introduced to identify and differentiate CD- and EC-induced oxidation. Using this approach, we separated the instantaneous CD-induced oxidation from the hysteretic EC-induced oxidation, and the effects of the spray voltage and flow rate of the ESI source on both oxidation types were investigated with a homemade ESI source. For angiotensin II analogue (b-DRVYVHPF-y), the dehydrogenation and oxygenation species were the detected EC-induced oxidation products, while the oxygenation species were the major CD-induced oxidation products. This time-resolved approach was also applicable to a commercial HESI source, in which both CD and EC were responsible for hemoglobin and cytochrome c oxidation with upstream grounding while CD dominated the oxidation without upstream grounding. Copyright © 2018 Elsevier B.V. All rights reserved.

  16. Time-resolved GISAXS and cryo-microscopy characterization of block copolymer membrane formation

    KAUST Repository

    Marques, Debora S.

    2014-03-01

    Time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and cryo-microscopy were used for the first time to understand the pore evolution by copolymer assembly, leading to the formation of isoporous membranes with exceptional porosity and regularity. The formation of copolymer micelle strings in solution (in DMF/DOX/THF and DMF/DOX) was confirmed by cryo field emission scanning electron microscopy (cryo-FESEM) with a distance of 72 nm between centers of micelles placed in different strings. SAXS measurement of block copolymer solutions in DMF/DOX indicated hexagonal assembly with micelle-to-micelle distance of 84-87 nm for 14-20 wt% copolymer solutions. GISAXS in-plane peaks were detected, revealing order close to hexagonal. The d-spacing corresponding to the first peak in this case was 100-130 nm (lattice constant 115-150 nm) for 17 wt% copolymer solutions evaporating up to 100 s. Time-resolved cryo-FESEM showed the formation of incipient pores on the film surface after 4 s copolymer solution casting with distances between void centers of 125 nm. © 2014 Elsevier Ltd. All rights reserved.

  17. Time-Resolved Fluorometry Based Sandwich Hybridisation Assay for HLA-DQA1 Typing

    Science.gov (United States)

    Sjöroos, Minna; Ilonen, Jorma; Reijonen, Helena; Lövgren, Timo

    1998-01-01

    A microtitration plate based time-resolved fluorescence (TRF) hybridisation assay was developed for HLA typing utilising biotinylated sequence-specific catching probes and europium (Eu) labelled gene locus-specific detection probe to allow time-resolved fluorometer reading of the reaction. In an application for HLA-DQA typing a 228 base pair long region of the polymorphic exon 2 of DQA1 gene was amplified and the denatured PCR product distributed into streptavidin-coated microtitration wells together with the detection probe and one of the catching probes. After incubation and washes, the enhancement solution was added and specific hybridisation signal detected by measuring the emitted light. A series of 100 isolated genomic DNA samples were studied using biotinylated probes specific for DQA1*01, *0101/0104, *0103/0201/0601, *0201, *03, *0401/0601, *05 and *0502 alleles with results demonstrating the capacity of the test to detect aimed alleles. A series of whole blood spot samples were also studied and the results confirmed the applicability of this modification of the test. PMID:9706458

  18. Time-Resolved Fluorometry Based Sandwich Hybridisation Assay for HLA-DQA1 Typing

    Directory of Open Access Journals (Sweden)

    Minna Sjöroos

    1998-01-01

    Full Text Available A microtitration plate based time-resolved fluorescence (TRF hybridisation assay was developed for HLA typing utilising biotinylated sequence-specific catching probes and europium (Eu labelled gene locus-specific detection probe to allow time-resolved fluorometer reading of the reaction. In an application for HLA-DQA typing a 228 base pair long region of the polymorphic exon 2 of DQA1 gene was amplified and the denatured PCR product distributed into streptavidin-coated microtitration wells together with the detection probe and one of the catching probes. After incubation and washes, the enhancement solution was added and specific hybridisation signal detected by measuring the emitted light. A series of 100 isolated genomic DNA samples were studied using biotinylated probes specific for DQA1*01, *0101/0104, *0103/0201/0601, *0201, *03, *0401/0601, *05 and *0502 alleles with results demonstrating the capacity of the test to detect aimed alleles. A series of whole blood spot samples were also studied and the results confirmed the applicability of this modification of the test.

  19. Denoising time-resolved microscopy image sequences with singular value thresholding

    Energy Technology Data Exchange (ETDEWEB)

    Furnival, Tom, E-mail: tjof2@cam.ac.uk; Leary, Rowan K., E-mail: rkl26@cam.ac.uk; Midgley, Paul A., E-mail: pam33@cam.ac.uk

    2017-07-15

    Time-resolved imaging in microscopy is important for the direct observation of a range of dynamic processes in both the physical and life sciences. However, the image sequences are often corrupted by noise, either as a result of high frame rates or a need to limit the radiation dose received by the sample. Here we exploit both spatial and temporal correlations using low-rank matrix recovery methods to denoise microscopy image sequences. We also make use of an unbiased risk estimator to address the issue of how much thresholding to apply in a robust and automated manner. The performance of the technique is demonstrated using simulated image sequences, as well as experimental scanning transmission electron microscopy data, where surface adatom motion and nanoparticle structural dynamics are recovered at rates of up to 32 frames per second. - Highlights: • Correlations in space and time are harnessed to denoise microscopy image sequences. • A robust estimator provides automated selection of the denoising parameter. • Motion tracking and automated noise estimation provides a versatile algorithm. • Application to time-resolved STEM enables study of atomic and nanoparticle dynamics.

  20. Time-resolved energy spectrum of a pseudospark-produced high-brightness electron beam

    International Nuclear Information System (INIS)

    Myers, T.J.; Ding, B.N.; Rhee, M.J.

    1992-01-01

    The pseudospark, a fast low-pressure gas discharge between a hollow cathode and a planar anode, is found to be an interesting high-brightness electron beam source. Typically, all electron beam produced in the pseudospark has the peak current of ∼1 kA, pulse duration of ∼50 ns, and effective emittance of ∼100 mm-mrad. The energy information of this electron beam, however, is least understood due to the difficulty of measuring a high-current-density beam that is partially space-charge neutralized by the background ions produced in the gas. In this paper, an experimental study of the time-resolved energy spectrum is presented. The pseudospark produced electron beam is injected into a vacuum through a small pinhole so that the electrons without background ions follow single particle motion; the beam is sent through a negative biased electrode and the only portion of beam whose energy is greater than the bias voltage can pass through the electrode and the current is measured by a Faraday cup. The Faraday cup signals with various bias voltage are recorded in a digital oscilloscope. The recorded waveforms are then numerically analyzed to construct a time-resolved energy spectrum. Preliminary results are presented

  1. Time resolved high frequency spectrum of Br2 molecules using pulsed photoacoustic technique.

    Science.gov (United States)

    Yehya, Fahem; Chaudhary, A K

    2013-11-01

    The paper reports the time resolved spectral distribution of higher order acoustic modes generated in Br2 molecules using pulsed Photoacoustic (PA) technique. New time resolved vibrational spectrum of Br2 molecules are recorded using a single 532nm, pulses of 7ns duration at 10Hz repetition rate obtained from Q-switched Nd:YAG laser. Frank-Condon principle based assignments confirms the presence of 12 numbers of (ν″-ν') vibrational transitions covered by a single 532+2nm pulse profile. Inclusions of higher order zeroth modes in Bassel's function expansion series shows the probability of overlapping of different types of acoustic modes in the designed PA cells. These modes appear in the form of clusters which occupies higher frequency range. The study of decay behavior of PA signal with respect to time confirms the photolysis of Br2 at 532nm wavelength. In addition, the shifting and clustering effect of cavity eigen modes in Br2 molecules have been studied between 1 and 10ms time scale. The estimated Q-factor of PA cell (l=16cm, R=1.4cm) is 145±4 at 27kHz frequency. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Life-time resolved emission spectra in CdI2 crystals

    International Nuclear Information System (INIS)

    Kawabata, Seiji; Nakagawa, Hideyuki

    2007-01-01

    The emission spectrum of CdI 2 is composed of ultraviolet (UV), green (G) and yellow (Y and Y') bands peaking at 3.38, 2.50, 2.16 and 2.25 eV, respectively. In order to determine the initial states of the Y- and G-luminescence, decay curves have been measured at 6 and 80 K by varying emission energy. The observed decay curves are composed of two or three exponential components. These decay components were named τ 1 , τ 2 , τ 3 , τ 3' and τ 4 . The emission spectrum for each decay component, i.e., the life-time resolved emission spectrum, was constructed from the observed decay curves. At 6 K, three bands at 2.12, 2.49 and 2.64 eV are obtained for τ 1 , τ 2 and τ 3 components, respectively. At 80 K, a dominant band for the τ 4 component and a weak band for the τ 3' component appear on the same energy position at 2.25 eV. The origin of each emission band in the life-time resolved emission spectra will be briefly discussed

  3. Time-Resolved Phonons as a Microscopic Probe for Solid State Processes

    Science.gov (United States)

    Eckold, Götz

    Phonons reflect most directly the chemical interactions in solids. Hence, time-resolved, lattice-dynamical experiments yield detailed information about the trajectories and mechanisms of solid state reactions on a microscopic scale. The experimental determination of phonons in a wide range of wave vectors and frequencies is a domain of inelastic neutron scattering and requires usually rather long counting times. Real-time investigations therefore need sophisticated techniques in order to access the time regime down to microseconds. In the present contribution, the state of the art of time-resolved inelastic neutrons scattering (TRINS) is reviewed and its capability for the exploration of microscopic mechanisms of chemical processes and phase transitions in solids is demonstrated using two different examples. Demixing processes in model systems are used to show that the evolution of lattice dynamics allows one to distinguish clearly between the mechanisms of nucleation and growth on the one hand, and spinodal decomposition, on the other hand. In the latter case, the interatomic interactions and, hence, the phonon spectra, vary on a time scale of seconds while the average structure of the product phases as reflected by Bragg diffraction needs much longer times to evolve.

  4. Evaluation of unsteady pressure fields and forces in rotating airfoils from time-resolved PIV

    Science.gov (United States)

    Villegas, A.; Diez, F. J.

    2014-04-01

    The instantaneous pressure fields and aerodynamic loads are obtained for rotating airfoils from time-resolved particle image velocimetry (TR-PIV) measurements. These allowed evaluating the contribution from the local acceleration (unsteady acceleration) to the instantaneous forces. Traditionally, this term has been neglected for wind turbines with quasi-steady flows, but results show that it is a dominant term in the wake where high temporal variations in the flow field are present due to vortex shedding. Briefly, time-resolved particle image velocimetry TR-PIV measurements are used to calculate flow velocity fields and corresponding spatial and temporal derivatives. These derivatives are then used in the Poisson equation to solve for the pressure field and later used in the integral momentum equation to solve for the instantaneous forces. The robustness of the measurements is analyzed by calculating the PIV uncertainty and the independence of the calculated forces. The experimental mean aerodynamic forces are compared with theoretical predictions from the blade element momentum theory showing good agreement. The instantaneous pressure field showed dependence with time in the wake due to vortex shedding. The contribution to the instantaneous forces from each term in the integral momentum equation is evaluated. The analysis shows that the larger contributions to the normal force coefficient are from the unsteady and the pressure terms, and the larger contribution to the tangential force coefficient is from the convective term.

  5. Direct observation of ultrafast atomic motion using time-resolved X-ray diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Shymanovich, U.

    2007-11-13

    This thesis is dedicated to the study of the atomic motion in laser irradiated solids on a picosecond to subpicosecond time-scale using the time-resolved X-ray diffraction technique. In the second chapter, the laser system, the laser-plasma based X-ray source and the experimental setup for optical pump / X-ray probe measurements were presented. Chapter 3 is devoted to the characterization and comparison of different types of X-ray optics. Chapter 4 presented the time-resolved X-ray diffraction experiments performed for this thesis. The first two sections of this chapter discuss the measurements of initially unexpected strain-induced transient changes of the integrated reflectivity of the X-ray probe beam. The elimination of the strain-induced transient changes of the integrated reflectivity represented an important prerequisite to perform the study of lattice heating in Germanium after femtosecond optical excitation by measuring the transient Debye-Waller effect. The third section describes the investigations of acoustic waves upon ultrafast optical excitation and discusses the two different pressure contributions driving them: the thermal and the electronic ones. (orig.)

  6. Time-Resolved Study on Xanthene Dye-Sensitized Carbon Nitride Photocatalytic Systems.

    Science.gov (United States)

    Zhang, Huiyu; Li, Shuang; Lu, Rong; Yu, Anchi

    2015-10-07

    Dye sensitization is a promising strategy to extend the visible light absorption of carbon nitride (C3N4) and increase the photocatalytic hydrogen evolution efficiency of C3N4 under visible light irradiation. However, the interaction dynamics between C3N4 and a sensitized dye has not been reported in the literature. Herein, we selected four commonly used xanthene dyes such as fluorescein, dibromofluorescein, eosin Y, and erythrosine B and prepared their corresponding dye-sensitized-C3N4 composites. For the first time, we derived the electron transfer rate from the LUMO of each photoexcited xanthene dye to the conduction band of C3N4 using picoesecond time-resolved fluorescence measurements. We also obtained the reduction potentials of all selected xanthene dyes and C3N4 with cyclic voltammetry measurements. The cyclic voltammetry measurements gave a consistent result with the picosecond time-resolved fluorescence measurements. Besides, the possibility of the selected xanthene dye as an acceptor for the hole of the photoexcited C3N4 was also discussed. We believe this study is significant for the researcher to understanding the fundamental aspects in the xanthene dye-sensitized-C3N4 photocatalytic systems.

  7. A CTRW-based model of time-resolved fluorescence lifetime imaging in a turbid medium.

    Science.gov (United States)

    Chernomordik, Victor; Gandjbakhche, Amir H; Hassan, Moinuddin; Pajevic, Sinisa; Weiss, George H

    2010-12-01

    We develop an analytic model of time-resolved fluorescent imaging of photons migrating through a semi-infinite turbid medium bounded by an infinite plane in the presence of a single stationary point fluorophore embedded in the medium. In contrast to earlier models of fluorescent imaging in which photon motion is assumed to be some form of continuous diffusion process, the present analysis is based on a continuous-time random walk (CTRW) on a simple cubic lattice, the object being to estimate the position and lifetime of the fluorophore. Such information can provide information related to local variations in pH and temperature with potential medical significance. Aspects of the theory were tested using time-resolved measurements of the fluorescence from small inclusions inside tissue-like phantoms. The experimental results were found to be in good agreement with theoretical predictions provided that the fluorophore was not located too close to the planar boundary, a common problem in many diffusive systems.

  8. Time-resolved fluorescence studies of nucleotide flipping by restriction enzymes.

    Science.gov (United States)

    Neely, Robert K; Tamulaitis, Gintautas; Chen, Kai; Kubala, Marta; Siksnys, Virginijus; Jones, Anita C

    2009-11-01

    Restriction enzymes Ecl18kI, PspGI and EcoRII-C, specific for interrupted 5-bp target sequences, flip the central base pair of these sequences into their protein pockets to facilitate sequence recognition and adjust the DNA cleavage pattern. We have used time-resolved fluorescence spectroscopy of 2-aminopurine-labelled DNA in complex with each of these enzymes in solution to explore the nucleotide flipping mechanism and to obtain a detailed picture of the molecular environment of the extrahelical bases. We also report the first study of the 7-bp cutter, PfoI, whose recognition sequence (T/CCNGGA) overlaps with that of the Ecl18kI-type enzymes, and for which the crystal structure is unknown. The time-resolved fluorescence experiments reveal that PfoI also uses base flipping as part of its DNA recognition mechanism and that the extrahelical bases are captured by PfoI in binding pockets whose structures are quite different to those of the structurally characterized enzymes Ecl18kI, PspGI and EcoRII-C. The fluorescence decay parameters of all the enzyme-DNA complexes are interpreted to provide insight into the mechanisms used by these four restriction enzymes to flip and recognize bases and the relationship between nucleotide flipping and DNA cleavage.

  9. Structure and function of proteins investigated by crystallographic and spectroscopic time-resolved methods

    Science.gov (United States)

    Purwar, Namrta

    Biomolecules play an essential role in performing the necessary functions for life. The goal of this thesis is to contribute to an understanding of how biological systems work on the molecular level. We used two biological systems, beef liver catalase (BLC) and photoactive yellow protein (PYP). BLC is a metalloprotein that protects living cells from the harmful effects of reactive oxygen species by converting H2O2 into water and oxygen. By binding nitric oxide (NO) to the catalase, a complex was generated that mimics the Cat-H2O2 adduct, a crucial intermediate in the reaction promoted by the catalase. The Cat-NO complex is obtained by using a convenient NO generator (1-(N,N-diethylamino)diazen-1-ium-1,2-diolate). Concentrations up to 100˜200 mM are reached by using a specially designed glass cavity. With this glass apparatus and DEANO, sufficient NO occupation is achieved and structure determination of the catalase with NO bound to the heme iron becomes possible. Structural changes upon NO binding are minute. NO has a slightly bent geometry with respect to the heme normal, which results in a substantial overlap of the NO orbitals with the iron-porphyrin molecular orbitals. From the structure of the iron-NO complex, conclusions on the electronic properties of the heme iron can be drawn that ultimately lead to an insight into the catalytic properties of this enzyme. Enzyme kinetics is affected by additional parameters such as temperature and pH. Additionally, in crystallography, the absorbed X-ray dose may impair protein function. To address the effect of these parameters, we performed time-resolved crystallographic experiments on a model system, PYP. By collecting multiple time-series on PYP at increasing X-ray dose levels, we determined a kinetic dose limit up to which kinetically meaningful X-ray data sets can be collected. From this, we conclude that comprehensive time-series spanning up to 12 orders of magnitude in time can be collected from a single PYP

  10. Circular RNAs

    DEFF Research Database (Denmark)

    Han, Yi-Neng; Xia, Shengqiang; Zhang, Yuan-Yuan

    2017-01-01

    Circular RNAs (circRNAs) are a novel type of universal and diverse endogenous noncoding RNAs (ncRNAs) and they form a covalently closed continuous loop without 5' or 3' tails unlike linear RNAs. Most circRNAs are presented with characteristics of abundance, stability, conservatism, and often exhi...... and expression regulators, RBP sponges in cancer as well as current research methods of circRNAs, providing evidence for the significance of circRNAs in cancer diagnosis and clinical treatment....

  11. Time-resolved studies at PETRA III with a highly repetitive synchronized laser system

    Energy Technology Data Exchange (ETDEWEB)

    Schlie, Mortiz

    2013-09-15

    Atomic and molecular processes can nowadays be directly followed in the time domain. This is a core technique for a better understanding of the involved fundamental physics, thus auguring new applications in the future as well. Usually the so-called pump-probe technique making use of two synchronized ultrashort light pulses is utilized to obtain this time-resolved data. In this work, the development and characterization of a synchronization system enabling such pump-probe studies at the storage ring PETRA III in combination with an external, then synchronized fs-laser system is described. The synchronization is based on an extended PLL approach with three interconnected feedback loops allowing to monitor short-time losses of the lock and thus prevent them. This way, the jitter between the laser PHAROS and the PETRA III reference signal is reduced to {sigma} <5 ps. Thus the system allows to conduct experiments at a repetition rate of 130 kHz with a temporal resolution limited only by the X-ray pulse length. A major emphasis in the fundamental introductory chapters is an intuitive explanation of the basic principles of phase locked loops and the different aspects of phase noise to allow a deeper understanding of the synchronization. Furthermore, first pump-probe experiments conducted at different beamlines at PETRA III are presented, demonstrating the usability of the laser system in a scientific environment as well. In first characterizing experiments the pulse duration of PETRA III X-ray pulses has been measured to be 90 ps FWHM. In particular, there have been time resolved X-ray absorption spectroscopy experiments on Gaq3 and Znq2 conducted at beamline P11. First results show dynamics of the electronic excitation on the timescale of a few hundred pico seconds up to a few nano seconds and provide a basic understanding for further research on those molecules. For Gaq3 this data is analyzed in detail and compared with visible fluorescence measurements suggesting at

  12. Understanding optically stimulated charge movement in quartz and feldspar using time-resolved measurements

    Energy Technology Data Exchange (ETDEWEB)

    Ankjaergaard, C.

    2010-02-15

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) from quartz and feldspar are widely used in accident dosimetry and luminescence dating. In order to improve already existing methods or to develop new methods towards extending the current limits of the technique, it is important to understand the charge movement within these materials. Earlier studies have primarily focussed on examination of the trap behaviour; however, this only tells half of the story as OSL is a combination of charge stimulation and recombination. By using time-resolved OSL (TR-OSL), one can directly examine the recombination route(s), and thus obtain insight into the other half of the process involved in luminescence emission. This thesis studies the TR-OSL and optically stimulated phosphorescence signals from quartz and feldspars spanning several orders of magnitude in time (few ns to the seconds time scale) in order to identify various charge transport mechanisms in the different time regimes. The techniques employed are time-resolved OSL, continuous-wave OSL, TL, optically stimulated exo-electron (OSE) emission and time-resolved OSE. These different techniques are used in combination with variable thermal or optical stimulation energy. The thesis first delves into three main methodological developments, namely (i) research and development of the equipment for TR-OSL measurements, (ii) finding the best method for multiple-exponential analysis of a TR-OSL curve, and (iii) optimisation of the pulsing configuration for the best separation of quartz OSL from a mixed quarts-feldspar sample. It then proceeds to study the different charge transport mechanisms subsequent to an optical stimulation pulse in quartz and feldspars. The results obtained for quartz conclude that the main lifetime component in quartz represents an excited state lifetime of the recombination centre, and the more slowly decaying components on the millisecond to seconds time scale arise from charge recycling

  13. An integrated approach using high time-resolved tools to study the origin of aerosols

    Energy Technology Data Exchange (ETDEWEB)

    Di Gilio, A. [Chemistry Department, University of Bari, via Orabona, 4, 70126 Bari (Italy); ARPA PUGLIA, Corso Trieste, 27, 70126 Bari (Italy); Gennaro, G. de, E-mail: gianluigi.degennaro@uniba.it [Chemistry Department, University of Bari, via Orabona, 4, 70126 Bari (Italy); ARPA PUGLIA, Corso Trieste, 27, 70126 Bari (Italy); Dambruoso, P. [Chemistry Department, University of Bari, via Orabona, 4, 70126 Bari (Italy); ARPA PUGLIA, Corso Trieste, 27, 70126 Bari (Italy); Ventrella, G. [Chemistry Department, University of Bari, via Orabona, 4, 70126 Bari (Italy)

    2015-10-15

    Long-range transport of natural and/or anthropogenic particles can contribute significantly to PM10 and PM2.5 concentrations and some European cities often fail to comply with PM daily limit values due to the additional impact of particles from remote sources. For this reason, reliable methodologies to identify long-range transport (LRT) events would be useful to better understand air pollution phenomena and support proper decision-making. This study explores the potential of an integrated and high time-resolved monitoring approach for the identification and characterization of local, regional and long-range transport events of high PM. In particular, the goal of this work was also the identification of time-limited event. For this purpose, a high time-resolved monitoring campaign was carried out at an urban background site in Bari (southern Italy) for about 20 days (1st–20th October 2011). The integration of collected data as the hourly measurements of inorganic ions in PM{sub 2.5} and their gas precursors and of the natural radioactivity, in addition to the analyses of aerosol maps and hourly back trajectories (BT), provided useful information for the identification and chemical characterization of local sources and trans-boundary intrusions. Non-sea salt (nss) sulfate levels were found to increase when air masses came from northeastern Europe and higher dispersive conditions of the atmosphere were detected. Instead, higher nitrate and lower nss-sulfate concentrations were registered in correspondence with air mass stagnation and attributed to local traffic source. In some cases, combinations of local and trans-boundary sources were observed. Finally, statistical investigations such as the principal component analysis (PCA) applied on hourly ion concentrations and the cluster analyses, the Potential Source Contribution Function (PSCF) and the Concentration Weighted Trajectory (CWT) models computed on hourly back-trajectories enabled to complete a cognitive

  14. Time-resolved studies at PETRA III with a highly repetitive synchronized laser system

    International Nuclear Information System (INIS)

    Schlie, Mortiz

    2013-09-01

    Atomic and molecular processes can nowadays be directly followed in the time domain. This is a core technique for a better understanding of the involved fundamental physics, thus auguring new applications in the future as well. Usually the so-called pump-probe technique making use of two synchronized ultrashort light pulses is utilized to obtain this time-resolved data. In this work, the development and characterization of a synchronization system enabling such pump-probe studies at the storage ring PETRA III in combination with an external, then synchronized fs-laser system is described. The synchronization is based on an extended PLL approach with three interconnected feedback loops allowing to monitor short-time losses of the lock and thus prevent them. This way, the jitter between the laser PHAROS and the PETRA III reference signal is reduced to σ <5 ps. Thus the system allows to conduct experiments at a repetition rate of 130 kHz with a temporal resolution limited only by the X-ray pulse length. A major emphasis in the fundamental introductory chapters is an intuitive explanation of the basic principles of phase locked loops and the different aspects of phase noise to allow a deeper understanding of the synchronization. Furthermore, first pump-probe experiments conducted at different beamlines at PETRA III are presented, demonstrating the usability of the laser system in a scientific environment as well. In first characterizing experiments the pulse duration of PETRA III X-ray pulses has been measured to be 90 ps FWHM. In particular, there have been time resolved X-ray absorption spectroscopy experiments on Gaq3 and Znq2 conducted at beamline P11. First results show dynamics of the electronic excitation on the timescale of a few hundred pico seconds up to a few nano seconds and provide a basic understanding for further research on those molecules. For Gaq3 this data is analyzed in detail and compared with visible fluorescence measurements suggesting at least

  15. Time-resolved spectroscopy of laser-induced breakdown in water

    Science.gov (United States)

    Thomas, Robert J.; Hammer, Daniel X.; Noojin, Gary D.; Stolarski, David J.; Rockwell, Benjamin A.; Roach, William P.

    1996-05-01

    Laser pulses of 60-ps and 80-ps at a wavelength of 532-nm and 1064-nm respectively were used to produce laser induced breakdown in triple-distilled water. The resulting luminescent flash from the plasma was captured with an imaging spectrograph coupled to a streak camera with a 5-ps time resolution. The wavelength range was 350 to 900-nm. We present the resulting experimental data which gives plasma duration and time-resolved spectral information. Plasma temperature is also computed from the data. All parameters are presented at a pulse energy of 1-mJ and are compared with time-integrated spectra at the same pulse duration and at 5 to 7-ns pulse duration in a similar energy range.

  16. Further time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. [Argonne National Lab., IL (United States). Advanced Photon Source Accelerator Systems Div.; Wilke, M.D. [Los Alamos National Lab., NM (United States)

    1992-12-31

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  17. Further time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. (Argonne National Lab., IL (United States). Advanced Photon Source Accelerator Systems Div.); Wilke, M.D. (Los Alamos National Lab., NM (United States))

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 [mu]s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatialposition and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kick effects are reported as a function of charge.

  18. Time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. (Argonne National Lab., IL (United States)); Wilke, M.D. (Los Alamos National Lab., NM (United States))

    1992-01-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  19. Time-resolved electron-beam characterizations with optical transition radiation

    Energy Technology Data Exchange (ETDEWEB)

    Lumpkin, A.H. [Argonne National Lab., IL (United States); Wilke, M.D. [Los Alamos National Lab., NM (United States)

    1992-09-01

    Time-resolved characterizations of electron beams using optical transition radiation (OTR) as a prompt conversion mechanism have recently been extended on the Los Alamos Free-electron Laser (FEL) facility 40-MeV linac. Two key timescales for rf-linac driven FELs are the micropulse (10 ps) and the macropulse (5 {mu}s to 1 ms). In the past we have used gated, intensified cameras to select a single or few micropulses (25 to 400 ns gate width) out of the pulse train to evaluate submacropulse effects. Recently, we have obtained some of the first measurements of micropulse bunch length (7 to 10 ps) and submacropulse spatial position and profile using OTR and a Hamamatsu streak camera. Additionally, micropulse elongation effects and head-to-tail transverse kicks are reported as a function of charge.

  20. Laser-induced time-resolved spectrofluorometry and thermal lensing: applications in the nuclear industry

    International Nuclear Information System (INIS)

    Decambox, P.; Delorme, N.; Mauchien, P.; Moulin, C.

    1989-01-01

    Sensitive spectroscopic methods for the determination of actinides and lanthanides in various media are required in the nuclear industry. Laser-Induced Time-Resolved Spectrofluorometry (LITRS) for several actinides and lanthanides at very low levels and thermal lensing (TL) for oxidation state characterization allow these determinations. The set-up of LITRS is presented. Spectra, limit of detections and lifetimes obtained for U, Cm, Am, Eu, Gd, Tb, Dy, Ce, Sm, Tm are shown. Detection limit as low as 5.10 -12 M can be achieved. Examples of matrices encountered for the determination of uranium are given as well as comparison with mass spectrometry and alpha counting. The set-up of TL and performances obtained on plutonium as well as future developments are presented