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Sample records for short wavelength emission

  1. Self-amplified spontaneous emission for short wavelength coherent radiation

    International Nuclear Information System (INIS)

    Kim, K.J.; Xie, M.

    1992-09-01

    We review the recent progress in our understanding of the self-amplified spontaneous emission (SASE), emphasizing the application to short wavelength generation. Simple formulae are given for the start-up, exponential gain and the saturation of SASE. Accelerator technologies producing high brightness electron beams required for short wavelength SASE are discussed. An example utilizing electron beams from a photocathode-linac system to produce 4nm SASE in the multigigawatt range is presented

  2. Short wavelength FELS

    International Nuclear Information System (INIS)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs

  3. Short wavelength FELS

    Energy Technology Data Exchange (ETDEWEB)

    Sheffield, R.L.

    1991-01-01

    The generation of coherent ultraviolet and shorter wavelength light is presently limited to synchrotron sources. The recent progress in the development of brighter electron beams enables the use of much lower energy electron rf linacs to reach short-wavelengths than previously considered possible. This paper will summarize the present results obtained with synchrotron sources, review proposed short- wavelength FEL designs and then present a new design which is capable of over an order of magnitude higher power to the extreme ultraviolet. 17 refs., 10 figs.

  4. Short-wavelength out-of-band EUV emission from Sn laser-produced plasma

    Science.gov (United States)

    Torretti, F.; Schupp, R.; Kurilovich, D.; Bayerle, A.; Scheers, J.; Ubachs, W.; Hoekstra, R.; Versolato, O. O.

    2018-02-01

    We present the results of spectroscopic measurements in the extreme ultraviolet regime (7-17 nm) of molten tin microdroplets illuminated by a high-intensity 3 J, 60 ns Nd:YAG laser pulse. The strong 13.5 nm emission from this laser-produced plasma (LPP) is of relevance for next-generation nanolithography machines. Here, we focus on the shorter wavelength features between 7 and 12 nm which have so far remained poorly investigated despite their diagnostic relevance. Using flexible atomic code calculations and local thermodynamic equilibrium arguments, we show that the line features in this region of the spectrum can be explained by transitions from high-lying configurations within the Sn{}8+-Sn{}15+ ions. The dominant transitions for all ions but Sn{}8+ are found to be electric-dipole transitions towards the n = 4 ground state from the core-excited configuration in which a 4p electron is promoted to the 5s subshell. Our results resolve some long-standing spectroscopic issues and provide reliable charge state identification for Sn LPP, which could be employed as a useful tool for diagnostic purposes.

  5. Towards short wavelengths FELs workshop

    International Nuclear Information System (INIS)

    Ben-Zvi, I.; Winick, H.

    1993-01-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FELs offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FELs will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program

  6. Towards short wavelengths FELs workshop

    Science.gov (United States)

    Ben-Zvi, I.; Winick, H.

    1993-11-01

    This workshop was caged because of the growing perception in the FEL source community that recent advances have made it possible to extend FEL operation to wavelengths about two orders of magnitude shorter than the 240 nm that has been achieved to date. In addition short wavelength FEL's offer the possibilities of extremely high peak power (several gigawatts) and very short pulses (of the order of 100 fs). Several groups in the USA are developing plans for such short wavelength FEL facilities. However, reviewers of these plans have pointed out that it would be highly desirable to first carry out proof-of-principle experiments at longer wavelengths to increase confidence that the shorter wavelength devices will indeed perform as calculated. The need for such experiments has now been broadly accepted by the FEL community. Such experiments were the main focus of this workshop as described in the following objectives distributed to attendees: (1) Define measurements needed to gain confidence that short wavelength FEL's will perform as calculated. (2) List possible hardware that could be used to carry out these measurements in the near term. (3) Define a prioritized FEL physics experimental program and suggested timetable. (4) Form collaborative teams to carry out this program.

  7. Review of short wavelength lasers

    International Nuclear Information System (INIS)

    Hagelstein, P.L.

    1985-01-01

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references

  8. Review of short wavelength lasers

    Energy Technology Data Exchange (ETDEWEB)

    Hagelstein, P.L.

    1985-03-18

    There has recently been a substantial amount of research devoted to the development of short wavelength amplifiers and lasers. A number of experimental results have been published wherein the observation of significant gain has been claimed on transitions in the EUV and soft x-ray regimes. The present review is intended to discuss the main approaches to the creation of population inversions and laser media in the short wavelength regime, and hopefully aid workers in the field by helping to provide access to a growing literature. The approaches to pumping EUV and soft x-ray lasers are discussed according to inversion mechanism. The approaches may be divided into roughly seven categories, including collisional excitation pumping, recombination pumping, direct photoionization and photoexcitation pumping, metastable state storage plus optical pumping, charge exchange pumping, and finally, the extension of free electron laser techniques into the EUV and soft x-ray regimes. 250 references.

  9. Short wavelength FELs using the SLAC linac

    International Nuclear Information System (INIS)

    Winick, H.; Bane, K.; Boyce, R.

    1993-08-01

    Recent technological developments have opened the possibility to construct a device which we call a Linac Coherent Light Source (LCLS); a fourth generation light source, with brightness, coherence, and peak power far exceeding other sources. Operating on the principle of the free electron laser (FEL), the LCLS would extend the range of FEL operation to much aborter wavelength than the 240 mn that has so far been reached. We report the results of studies of the use of the SLAC linac to drive an LCLS at wavelengths from about 3-100 nm initially and possibly even shorter wavelengths in the future. Lasing would be achieved in a single pass of a low emittance, high peak current, high energy electron beam through a long undulator. Most present FELs use an optical cavity to build up the intensity of the light to achieve lasing action in a low gain oscillator configuration. By eliminating the optical cavity, which is difficult to make at short wavelengths, laser action can be extended to shorter wavelengths by Self-Amplified-Spontaneous-Emission (SASE), or by harmonic generation from a longer wavelength seed laser. Short wavelength, single pass lasers have been extensively studied at several laboratories and at recent workshops

  10. Short wavelength sources and atoms and ions

    International Nuclear Information System (INIS)

    Kennedy, E.T.

    2008-01-01

    The interaction of ionizing radiation with atoms and ions is a key fundamental process. Experimental progress has depended in particular on the development of short wavelength light sources. Laser-plasma and synchrotron sources have been exploited for several decades and most recently the development of short wavelength Free Electron Laser (FEL) sources is revolutionizing the field. This paper introduces laser plasma and synchrotron sources through examples of their use in studies of the interaction of ionizing radiation with atoms and ions, ranging from few-electron atomic and ionic systems to the many-electron high atomic number actinides. The new FEL source (FLASH) at DESY is introduced. (author)

  11. Estimates of SASE power in the short wavelength region

    International Nuclear Information System (INIS)

    Kim, Kwang-Je.

    1992-03-01

    Given a sufficiently bright electron beam, the self-amplified-spontaneous emission (SASE) can provide gigawatts of short wavelength coherent radiation. The advantages of SASE approach are that is requires neither optical cavity nor an imput seed laser. In this note, we estimate the peak power performance of SASE for wavelengths shorter than 1000 Angstrom. At each wavelength, we calculate the saturated power from a uniform parameter undulator and the enhanced power from a tapered undulator. The method described here is an adaptation of that discussed by L.H. Yu, who discussed the harmonic generation scheme with seeded laser, to the case of SASE

  12. Optical Detection in Ultrafast Short Wavelength Science

    International Nuclear Information System (INIS)

    Fullagar, Wilfred K.; Hall, Chris J.

    2010-01-01

    A new approach to coherent detection of ionising radiation is briefly motivated and recounted. The approach involves optical scattering of coherent light fields by colour centres in transparent solids. It has significant potential for diffractive imaging applications that require high detection dynamic range from pulsed high brilliance short wavelength sources. It also motivates new incarnations of Bragg's X-ray microscope for pump-probe studies of ultrafast molecular structure-dynamics.

  13. Short wavelength striations on expanding plasma clouds

    International Nuclear Information System (INIS)

    Winske, D.; Gary, S.P.

    1989-01-01

    The growth and evolution of short wavelength (< ion gyroradius) flute modes on a plasma expanding across an ambient magnetic field have been actively studied in recent years, both by means of experiments in the laboratory as well as in space and through numerical simulations. We review the relevant observations and simulations results, discuss the instability mechanism and related linear theory, and describe recent work to bring experiments and theory into better agreement. 30 refs., 6 figs

  14. Short wavelength limits of current shot noise suppression

    International Nuclear Information System (INIS)

    Nause, Ariel; Dyunin, Egor; Gover, Avraham

    2014-01-01

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect

  15. Short wavelength limits of current shot noise suppression

    Energy Technology Data Exchange (ETDEWEB)

    Nause, Ariel, E-mail: arielnau@post.tau.ac.il [Faculty of Exact Sciences, Department of Physics, Tel Aviv University, Tel Aviv (Israel); Dyunin, Egor; Gover, Avraham [Faculty of Engineering, Department of Physical Electronics, Tel Aviv University, Tel Aviv (Israel)

    2014-08-15

    Shot noise in electron beam was assumed to be one of the features beyond control of accelerator physics. Current results attained in experiments at Accelerator Test Facility in Brookhaven and Linac Coherent Light Source in Stanford suggest that the control of the shot noise in electron beam (and therefore of spontaneous radiation and Self Amplified Spontaneous Emission of Free Electron Lasers) is feasible at least in the visible range of the spectrum. Here, we present a general linear formulation for collective micro-dynamics of e-beam noise and its control. Specifically, we compare two schemes for current noise suppression: a quarter plasma wavelength drift section and a combined drift/dispersive (transverse magnetic field) section. We examine and compare their limits of applicability at short wavelengths via considerations of electron phase-spread and the related Landau damping effect.

  16. Research with high-power short-wavelength lasers

    International Nuclear Information System (INIS)

    Holzrichter, J.F.; Campbell, E.M.; Lindl, J.D.; Storm, E.

    1985-01-01

    Three important high-temperature, high-density experiments were conducted recently using the 10-TW, short-wavelength Novette laser system at the Lawrence Livermore National Laboratory. These experiments demonstrated successful solutions to problems that arose during previous experiments with long wavelength lasers (lambda greater than or equal to 1μm) in which inertial confinement fusion (ICF), x-ray laser, and other high-temperature physics concepts were being tested. The demonstrations were: (1) large-scale plasmas (typical dimensions of up to 1000 laser wavelengths) were produced in which potentially deleterious laser-plasma instabilities were collisionally damped. (2) Deuterium-tritium fuel was imploded to a density of 20 g/cm 3 and a pressure of 10 10 atm. (3) A 700-fold amplification of soft x rays by stimulated emission at 206 and 209 A (62 eV) from Se +24 ions was observed in a laser-generated plasma. Isoelectronic scaling to 155 A (87 eV) in Y +29 was also demonstrated

  17. Emission wavelength of multilayer distributed feedback dye lasers

    DEFF Research Database (Denmark)

    Vannahme, Christoph; Smith, Cameron L. C.; Brøkner Christiansen, Mads

    2012-01-01

    Precise emission wavelength modeling is essential for understanding and optimization of distributed feedback (DFB) lasers. An analytical approach for determining the emission wavelength based on setting the propagation constant of the Bragg condition and solving for the resulting slab waveguide m...

  18. Nonlinear propagation of short wavelength drift-Alfven waves

    DEFF Research Database (Denmark)

    Shukla, P. K.; Pecseli, H. L.; Juul Rasmussen, Jens

    1986-01-01

    Making use of a kinetic ion and a hydrodynamic electron description together with the Maxwell equation, the authors derive a set of nonlinear equations which governs the dynamics of short wavelength ion drift-Alfven waves. It is shown that the nonlinear drift-Alfven waves can propagate as two-dim...

  19. Study of the correlation of scintillation decay and emission wavelength

    International Nuclear Information System (INIS)

    Yanagida, Takayuki; Fujimoto, Yutaka; Yamaji, Akihiro; Kawaguchi, Noriaki; Kamada, Kei; Totsuka, Daisuke; Fukuda, Kentaro; Yamanoi, Kohei; Nishi, Ryosuke; Kurosawa, Shunsuke; Shimizu, Toshihiko; Sarukura, Nobuhiko

    2013-01-01

    In photoluminescence which directly excites the emission center of phosphor material is known to have a correlation between the emission wavelength and the decay time based on quantum mechanics. In scintillation phenomenon, host lattice of the material is first excited by ionizing radiation and then the excitation energy is transferred to emission centers. For the first time, we investigated the correlation between the scintillation decay and the emission wavelength by using pulse X-ray equipped streak camera system which could observe time and wavelength resolved scintillation phenomenon. Investigated materials were Ce 3+ , Pr 3+ and Nd 3+ doped oxides and fluorides which all showed 5d-4f transition based emission. As a result, we obtained the relation that τ (scintillation decay time) was proportional to the λ 2.15 (emission wavelength). -- Highlights: ► The correlation between emission wavelength and scintillation decay time is investigated. ► Photoluminescence decay times are also evaluated and compared with scintillation decay times. ► It is proved the relaxation process in emission center is dominant even in scintillation decay

  20. OMEGA: a short-wavelength laser for fusion experiments

    International Nuclear Information System (INIS)

    Soures, J.M.; Hutchison, R.J.; Jacobs, S.D.; Lund, L.D.; McCrory, R.L.; Richardson, M.C.

    1983-01-01

    The OMEGA, Nd:glass laser facility was constructed for the purpose of investigating the feasibility of direct-drive laser fusion. With 24 beams producing a total energy of 4 kJ or a peak power of 12 TW, OMEGA is capable of nearly uniform illumination of spherical targets. Six of the OMEGA beams have recently been converted to short-wavelength operation (351 nm). In this paper, we discuss details of the system design and performance, with particular emphasis on the frequency-conversion system and multi-wavelength diagnostic system

  1. Local Analysis Approach for Short Wavelength Geopotential Variations

    Science.gov (United States)

    Bender, P. L.

    2009-12-01

    The value of global spherical harmonic analyses for determining 15 day to 30 day changes in the Earth's gravity field has been demonstrated extensively using data from the GRACE mission and previous missions. However, additional useful information appears to be obtainable from local analyses of the data. A number of such analyses have been carried out by various groups. In the energy approximation, the changes in the height of the satellite altitude geopotential can be determined from the post-fit changes in the satellite separation during individual one-revolution arcs of data from a GRACE-type pair of satellites in a given orbit. For a particular region, it is assumed that short wavelength spatial variations for the arcs crossing that region during a time T of interest would be used to determine corrections to the spherical harmonic results. The main issue in considering higher measurement accuracy in future missions is how much improvement in spatial resolution can be achieved. For this, the shortest wavelengths that can be determined are the most important. And, while the longer wavelength variations are affected by mass distribution changes over much of the globe, the shorter wavelength ones hopefully will be determined mainly by more local changes in the mass distribution. Future missions are expected to have much higher accuracy for measuring changes in the satellite separation than GRACE. However, how large an improvement in the derived results in hydrology will be achieved is still very much a matter of study, particularly because of the effects of uncertainty in the time variations in the atmospheric and oceanic mass distributions. To be specific, it will be assumed that improving the spatial resolution in continental regions away from the coastlines is the objective, and that the satellite altitude is in the range of roughly 290 to 360 km made possible for long missions by drag-free operation. The advantages of putting together the short wavelength

  2. Short-wavelength magnetic recording new methods and analyses

    CERN Document Server

    Ruigrok, JJM

    2013-01-01

    Short-wavelength magnetic recording presents a series of practical solutions to a wide range of problems in the field of magnetic recording. It features many new and original results, all derived from fundamental principles as a result of up-to-date research.A special section is devoted to the playback process, including the calculations of head efficiency and head impedance, derived from new theorems.Features include:A simple and fast method for measuring efficiency; a simple method for the accurate separation of the read and write behaviour of magnetic heads; a new concept - the bandpass hea

  3. Experimental tests of induced spatial incoherence using short laser wavelength

    International Nuclear Information System (INIS)

    Obenschain, S.P.; Grun, J.; Herbst, M.J.

    1986-01-01

    The authors have developed a laser beam smoothing technique called induced spatial incoherence (ISI), which can produce the highly uniform focal profiles required for direct-drive laser fusion. Uniform well-controlled focal profiles are required to obtain the highly symmetric pellet implosions needed for high-energy gain. In recent experiments, the authors' tested the effects of ISI on high-power laser-target interaction. With short laser wavelength, the coupling physics dramatically improved over that obtained with an ordinary laser beam

  4. Stability of short wavelength tearing and twisting modes

    International Nuclear Information System (INIS)

    Waelbroeck, F.L.

    1998-01-01

    The stability and mutual interaction of tearing and twisting modes in a torus is governed by matrices that generalize the well-known Δ' stability index. The diagonal elements of these matrices determine the intrinsic stability of modes that reconnect the magnetic field at a single resonant surface. The off-diagonal elements indicate the strength of the coupling between the different modes. The author shows how the elements of these matrices can be evaluated, in the limit of short wavelength, from the free energy driving radially extended ballooning modes. The author applies the results by calculating the tearing and twisting Δ' for a model high-beta equilibrium with circular flux surfaces

  5. Enhanced Plasmonic Wavelength Selective Infrared Emission Combined with Microheater

    Directory of Open Access Journals (Sweden)

    Hiroki Ishihara

    2017-09-01

    Full Text Available The indirect wavelength selective thermal emitter that we have proposed is constructed using a new microheater, demonstrating the enhancement of the emission peak generated by the surface plasmon polariton. The thermal isolation is improved using a 2 μm-thick Si membrane having 3.6 and 5.4 mm outer diameter. The emission at around the wavelength of the absorption band of CO2 gas is enhanced. The absorption signal increases, confirming the suitability for gas sensing. Against input power, the intensity at the peak wavelength shows a steeper increasing ratio than the background intensity. The microheater with higher thermal isolation gives larger peak intensity and its increasing ratio against the input power.

  6. Short-wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1985-01-01

    Recent observations with the ISEE 1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emission has a characteristic parabola shape or ''festoon'' shape. The low-frequency cutoff ranges from 100 to 400 Hz, while the high-frequency limit ranges from about 1 to 4 kHz. The bandwidth is found to minimize for antenna orientations parallel to the wave vectors. The wave vector does not appear to be related to the local magnetic field, the plasma flow velocity, or the spacecraft-sun directions. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler-shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest frame wave vectors and frequencies indicate that emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 40 and 600 m. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  7. Short wavelength electrostatic waves in the earth's magnetosheath

    International Nuclear Information System (INIS)

    Gallagher, D.L.

    1982-01-01

    Recent observations with the ISEE-1 spacecraft have found electric field emissions in the dayside magnetosheath whose frequency spectrum is modulated at twice the spacecraft spin period. The upper frequency cutoff in the frequency-time spectrum of the emissions has a characteristic parabola shape or ''festoon'' shape. The low frequency cutoff ranges from 100 Hz to 400 Hz, while the high frequency limit ranges from about 1kHz to 4kHz. The bandwidth is found to minimize for antenna orientations parallel to these wave number vectors, requiring the confinement of those vectors to a plane which contains the geocentric solar eclilptic coordinate z-axis. The spacecraft observed frequency spectrum results from the spacecraft antenna response to the Doppler shifted wave vector spectrum which exists in the plasma. Imposed constraints on the plasma rest-frame wave vectors and frequencies indicate that the emissions occur within the frequency range from about 150 Hz to 1 kHz, with wavelengths between about 30 meters and 600 meters. These constraints strongly suggest that the festoon-shaped emissions are ion-acoustic waves. The small group velocity and k vector direction of the ion-acoustic mode are consistent with wave generation upstream at the bow shock and convection downstream to locations within the outer dayside magnetosheath

  8. Observation of magnon-phonon interaction at short wavelengths

    International Nuclear Information System (INIS)

    Dolling, G.; Cowley, R.A.

    1966-01-01

    Measurements have been made of the magnon and phonon dispersion relations in uranium dioxide at 9 o K. These measurements provide evidence of a strong interaction between the magnon and phonon excitations and enable a value to be deduced for the coupling constant. The interaction of long-wavelength magnons in ferromagnetic materials has been studied previously with ultrasonic techniques; however, inelastic scattering of slow neutrons enables both the magnon and phonon dispersion relations to be determined for short wavelengths. In those magnetic materials which have been studied by earlier workers, the magnons and phonons either interacted with one another very weakly or else their frequencies were very different. The results could then be understood without introducing any magnon-phonon interaction. In this note we report measurements of both the magnon and the phonon spectra of antiferromagnetic uranium dioxide, which lead to a magnon-phonon coupling constant of 9.6 ± 1.6 o K. Since the Neel temperature is 30.8 o K, this coupling constant is of a similar magnitude to the direct magnetic interactions. (author)

  9. Self Referencing Heterodyne Transient Grating Spectroscopy with Short Wavelength

    Directory of Open Access Journals (Sweden)

    Jakob Grilj

    2015-04-01

    Full Text Available Heterodyning by a phase stable reference electric field is a well known technique to amplify weak nonlinear signals. For short wavelength, the generation of a reference field in front of the sample is challenging because of a lack of suitable beamsplitters. Here, we use a permanent grating which matches the line spacing of the transient grating for the creation of a phase stable reference field. The relative phase among the two can be changed by a relative translation of the permanent and transient gratings in direction orthogonal to the grating lines. We demonstrate the technique for a transient grating on a VO2 thin film and observe constructive as well as destructive interference signals.

  10. Beam dynamics simulations for linacs driving short-wavelength FELs

    International Nuclear Information System (INIS)

    Ferrario, M.; Tazzioli, F.

    1999-01-01

    The fast code HOMDYN has been recently developed, in the framework of the TTF (Tesla test facility) collaboration, in order to study the beam dynamics of linacs delivering high brightness beams as those needed for short wavelength Fel experiments. These linacs are typically driven by radio-frequency photo-injectors, where correlated time dependent space charge effects are of great relevance: these effects cannot be studied by standard beam optics codes (TRACE3D, etc.) and they have been modeled so far by means of multi-particle (Pic or quasistatic) codes requiring heavy cpu time and memory allocations. HOMDYN is able to describe the beam generation at the photo-cathode and the emittance compensation process in the injector even running on a laptop with very modest running rimes (less than a minute). In this paper it is showed how this capability of the code is exploited so to model a whole linac up to the point where the space charge dominated regime is of relevance (200 MeV)

  11. Interferometry on small quantum systems at short wavelength

    International Nuclear Information System (INIS)

    Usenko, Sergey

    2017-01-01

    The present work concentrates on prototypical studies of light-induced correlated many-body dynamics in complex systems. In its course a reflective split-and-delay unit (SDU) for phase-resolved one-color pump-probe experiments with gas phase samples using VUV-XUV laser pulses was built. The collinear propagation of pump and probe pulses is ensured by the special geometry of the SDU and allows to perform phase-resolved (coherent) autocorrelation measurements. The control of the pump-probe delay with attosecond precision is established by a specially developed diagnostic tool based on an in-vacuum white light interferometer that allows to monitor the relative displacement of the SDU reflectors with nanometer resolution. Phase-resolved (interferometric) pump-probe experiments with developed SDU require spatially-resolved imaging of the ionization volume. For this an electron-ion coincidence spectrometer was built. The spectrometer enables coincident detection of photoionization products using velocity map imaging (VMI) technique for electrons and VMI or spatial imaging for ions. In first experiments using the developed SDU and the spectrometer in the ion spatial-imaging mode linear field autocorrelation of free-electron laser pulses at the central wavelength of 38 nm was recorded. A further focus of the work were energy- and time-resolved resonant two-photon ionization experiments using short tunable UV laser pulses on C_6_0 fullerene. The experiments demonstrated that dipole-selective excitation on a timescale faster than the characteristic intramolecular energy dissipation limits the number of accessible excitation pathways and thus results in a narrow resonance. Time-dependent one-color pump-probe study showed that nonadiabatic (vibron) coupling is the dominant energy dissipation mechanism for high-lying electronic excited states in C_6_0.

  12. Interferometry on small quantum systems at short wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Usenko, Sergey

    2017-01-15

    The present work concentrates on prototypical studies of light-induced correlated many-body dynamics in complex systems. In its course a reflective split-and-delay unit (SDU) for phase-resolved one-color pump-probe experiments with gas phase samples using VUV-XUV laser pulses was built. The collinear propagation of pump and probe pulses is ensured by the special geometry of the SDU and allows to perform phase-resolved (coherent) autocorrelation measurements. The control of the pump-probe delay with attosecond precision is established by a specially developed diagnostic tool based on an in-vacuum white light interferometer that allows to monitor the relative displacement of the SDU reflectors with nanometer resolution. Phase-resolved (interferometric) pump-probe experiments with developed SDU require spatially-resolved imaging of the ionization volume. For this an electron-ion coincidence spectrometer was built. The spectrometer enables coincident detection of photoionization products using velocity map imaging (VMI) technique for electrons and VMI or spatial imaging for ions. In first experiments using the developed SDU and the spectrometer in the ion spatial-imaging mode linear field autocorrelation of free-electron laser pulses at the central wavelength of 38 nm was recorded. A further focus of the work were energy- and time-resolved resonant two-photon ionization experiments using short tunable UV laser pulses on C{sub 60} fullerene. The experiments demonstrated that dipole-selective excitation on a timescale faster than the characteristic intramolecular energy dissipation limits the number of accessible excitation pathways and thus results in a narrow resonance. Time-dependent one-color pump-probe study showed that nonadiabatic (vibron) coupling is the dominant energy dissipation mechanism for high-lying electronic excited states in C{sub 60}.

  13. Towards shorter wavelength x-ray lasers using a high power, short pulse pump laser

    International Nuclear Information System (INIS)

    Tighe, W.; Krushelnick, K.; Valeo, E.; Suckewer, S.

    1991-05-01

    A near-terawatt, KrF* laser system, focussable to power densities >10 18 W/cm 2 has been constructed for use as a pump laser in various schemes aimed at the development of x-ray lasing below 5nm. The laser system along with output characteristics such as the pulse duration, the focal spot size, and the percentage of amplified spontaneous emission (ASE) emitted along with the laser pulse will be presented. Schemes intended to lead to shorter wavelength x-ray emission will be described. The resultant requirements on the pump laser characteristics and the target design will be outlined. Results from recent solid target experiments and two-laser experiments, showing the interaction of a high-power, short pulse laser with a preformed plasma, will be presented. 13 refs., 5 figs

  14. Observation of Rayleigh - Taylor growth to short wavelengths on Nike

    International Nuclear Information System (INIS)

    Pawley, C.J.; Bodner, S.E.; Dahlburg, J.P.; Obenschain, S.P.; Schmitt, A.J.; Sethian, J.D.; Sullivan, C.A.; Gardner, J.H.; Aglitskiy, Y.; Chan, Y.; Lehecka, T.

    1999-01-01

    The uniform and smooth focal profile of the Nike KrF laser [S. Obenschain et al., Phys. Plasmas 3, 2098 (1996)] was used to ablatively accelerate 40 μm thick polystyrene planar targets with pulse shaping to minimize shock heating of the compressed material. The foils had imposed small-amplitude sinusoidal wave perturbations of 60, 30, 20, and 12.5 μm wavelength. The shortest wavelength is near the ablative stabilization cutoff for Rayleigh - Taylor growth. Modification of the saturated wave structure due to random laser imprint was observed. Excellent agreement was found between the two-dimensional simulations and experimental data for most cases where the laser imprint was not dominant. copyright 1999 American Institute of Physics

  15. Scaling model for high-aspect-ratio microballoon direct-drive implosions at short laser wavelengths

    International Nuclear Information System (INIS)

    Schirmann, D.; Juraszek, D.; Lane, S.M.; Campbell, E.M.

    1992-01-01

    A scaling model for hot spherical ablative implosions in direct-drive mode is presented. The model results have been compared with experiments from LLE, ILE, and LLNL. Reduction of the neutron yield due to illumination nonuniformities is taken into account by the assumption that the neutron emission is cut off when the gas shock wave reflected off the center meets the incoming pusher, i.e., at a time when the probability of shell breakup is greatly enhanced. The main advantage of this semiempirical scaling model is that it elucidates the principal features of these simple implosions and permits one to estimate very quickly the performance of a high-aspect-ratio direct-drive target illuminated by short-wavelength laser light. (Author)

  16. Short-wavelength InAlGaAs/AlGaAs quantum dot superluminescent diodes

    Science.gov (United States)

    Liang, De-Chun; An, Qi; Jin, Peng; Li, Xin-Kun; Wei, Heng; Wu, Ju; Wang, Zhan-Guo

    2011-10-01

    This paper reports the fabrication of J-shaped bent-waveguide superluminescent diodes utilizing an InAlGaAs/AlGaAs quantum dot active region. The emission spectrum of the device is centred at 884 nm with a full width at half maximum of 37 nm and an output power of 18 mW. By incorporating an Al composition into the quantum dot active region, short-wavelength superluminescent diode devices can be obtained. An intersection was found for the light power-injection current curves measured from the straight-waveguide facet and the bent-waveguide facet, respectively. The result is attributed to the conjunct effects of the gain and the additional loss of the bent waveguide. A numerical simulation is performed to verify the qualitative explanation. It is shown that bent waveguide loss is an important factor that affects the output power of J-shaped superluminescent diode devices.

  17. Digitally tunable dual wavelength emission from semiconductor ring lasers with filtered optical feedback

    International Nuclear Information System (INIS)

    Khoder, Mulham; Verschaffelt, Guy; Nguimdo, Romain Modeste; Danckaert, Jan; Leijtens, Xaveer; Bolk, Jeroen

    2013-01-01

    We report on a novel integrated approach to obtain dual wavelength emission from a semiconductor laser based on on-chip filtered optical feedback. Using this approach, we show experiments and numerical simulations of dual wavelength emission of a semiconductor ring laser. The filtered optical feedback is realized on-chip by employing two arrayed waveguide gratings to split/recombine light into different wavelength channels. Semiconductor optical amplifiers are placed in the feedback loop in order to control the feedback strength of each wavelength channel independently. By tuning the current injected into each of the amplifiers, we can effectively cancel the gain difference between the wavelength channels due to fabrication and material dichroism, thus resulting in stable dual wavelength emission. We also explore the accuracy needed in the operational parameters to maintain this dual wavelength emission. (letter)

  18. Single Mode Fiber Optic Transceiver Using Short Wavelength Active Devices In Long Wavelength Fiber

    Science.gov (United States)

    Gillham, Frederick J.; Campbell, Daniel R.; Corke, Michael; Stowe, David W.

    1990-01-01

    Presently, single mode optical fiber technology is being utilized in systems to supply telephone service to the subscriber. However, in an attempt to be competitive with copper based systems, there are many development programs underway to determine the most cost effective solution while still providing a service that will either satisfy or be upgradeable to satisfy the demands of the consumer for the next 10 to 20 years. One such approach is to combine low cost laser transmitters and silicon receivers, which have been developed for the "compact disc" industry, with fiber that operates in the single mode regime at 1300 nm. In this paper, an optical transceiver will be presented, consisting of a compact disc laser, a silicon detector and a single mode coupler at 1300 nm. A possible system layout is presented which operates at 780 nm bi-directionally for POTS and upgradeable to 1300 nm for video services. There are several important design criteria that have to be considered in the development of such a system which will be addressed. These include: 1. Optimization of coupled power from laser to fiber while maintaining stable launched conditions over a wide range of environmental conditions. 2. Consideration of the multimode operation of the 1300 nm single mode fiber while operating in the 780 nm wavelength region. 3. Development of a low cost pseudo-wavelength division multiplexer for 1300 nm single mode/780 nm multimode operation and a low cost dual mode 50/50, 780 nm splitter using 1300 nm fiber. Details will be given of the design criteria and solution in terms of optimized design. Results of the performance of several prototype devices will be given with indications of the merits of this approach and where further development effort should be applied.

  19. Sexual dimorphism of short-wavelength photoreceptors in the small white butterfly, Pieris rapae crucivora

    NARCIS (Netherlands)

    Arikawa, K; Wakakuwa, M; Qiu, XD; Kurasawa, M; Stavenga, DG; Qiu, Xudong

    2005-01-01

    The eyes of the female small white butterfly, Pieris rapae crucivora, are furnished with three classes of short-wavelength photoreceptors, with sensitivity peaks in the ultraviolet (UV) (lambda(max) = 360 nm), violet (V) (lambda max = 425 nm), and blue (B) (lambda(max) = 453 nm) wavelength range.

  20. Introduction: a short-wavelength-FEL/storage-ring complex

    International Nuclear Information System (INIS)

    Sessler, A.M.

    1984-01-01

    We believe that, in view of the present state of FEL understanding, it is now proper to construct a research facility devoted to the use of coherent radiation and the advancement of FEL physics technology at wavelengths shorter than 1000 A. We show a possible layout of such a facility, which will be referred to as a Coherent xuv Facility (CXF), where research can be conducted on several techniques for generating coherent radiation. Undulators are already well understood and will generate broadly tunable, spatially coherent radiation of bandwidth lambda /Δlambda approx. = 10 2 . A crossed undulator system will extend the undulator capability to include variable polarization. For full coherence, in spatial as well as in longitudinal directions, it is necessary to induce and exploit density modulation in electron beams, as is the case in the transverse optical klystrons (TOKs) and FELs. In TOKs, coherent radiation is generated at harmonics of an input laser frequency, with the electron beam playing the role of a nonlinear medium. Ultimately, FELS would deliver intense, tunable x rays and vuv radiation of extremely narrow spectral width. There are two possible routes to an FEL, one based on feedback by end mirrors, the other based on development of a high-gain, single-pass device. It can be seen, from this paper, that the photon flux increases monotonically, or the wavelength decreases monotonically, as one goes through (1) undulator radiation, (2) TOK radiation, (3) FEL oscillator radiation, to (4) FEL single-pass radiation. Each of these will demand considerable quality development effort. Each will result in photon fluxes of increased value to the users

  1. Short Wavelength Electrostatic Waves in the Earth’s Magnetosheath.

    Science.gov (United States)

    1982-07-01

    to an antenna effect. Emissions likely to be ion-acoustic mode waves have been found up- stream of the bow shock ( foreshock ) in the solar wind...particles apparently reflected at the bow shock and associated with ion- acoustic mode waves in the Earth’s foreshock are also observed [Eastman et al...Res., 86, A 4493-4510, 1981. Eastman, T.E., 1.R. Anderson, L.A. Frank, and G.K. Parks, Upstream particles observed in the Earth’s foreshock region

  2. Controlling the emission wavelength in group III-V semiconductor laser diodes

    KAUST Repository

    Ooi, Boon S.; Majid, Mohammed Abdul; Afandy, Rami; Aljabr, Ahmad

    2016-01-01

    Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III

  3. Differentiation of ocular fundus fluorophores by fluorescence lifetime imaging using multiple excitation and emission wavelengths

    Science.gov (United States)

    Hammer, M.; Schweitzer, D.; Schenke, S.; Becker, W.; Bergmann, A.

    2006-10-01

    Ocular fundus autofluorescence imaging has been introduced into clinical diagnostics recently. It is in use for the observation of the age pigment lipofuscin, a precursor of age - related macular degeneration (AMD). But other fluorophores may be of interest too: The redox pair FAD - FADH II provides information on the retinal energy metabolism, advanced glycation end products (AGE) indicate protein glycation associated with pathologic processes in diabetes as well as AMD, and alterations in the fluorescence of collagen and elastin in connective tissue give us the opportunity to observe fibrosis by fluorescence imaging. This, however, needs techniques able to differentiate particular fluorophores despite limited permissible ocular exposure as well as excitation wavelength (limited by the transmission of the human ocular lens to >400 nm). We present an ophthalmic laser scanning system (SLO), equipped with picosecond laser diodes (FWHM 100 ps, 446 nm or 468 nm respectively) and time correlated single photon counting (TCSPC) in two emission bands (500 - 560 nm and 560 - 700 nm). The decays were fitted by a bi-exponential model. Fluorescence spectra were measured by a fluorescence spectrometer fluorolog. Upon excitation at 446 nm, the fluorescence of AGE, FAD, and lipofuscin were found to peak at 503 nm, 525 nm, and 600 nm respectively. Accordingly, the statistical distribution of the fluorescence decay times was found to depend on the different excitation wavelengths and emission bands used. The use of multiple excitation and emission wavelengths in conjunction with fluorescence lifetime imaging allows us to discriminate between intrinsic fluorophores of the ocular fundus. Taken together with our knowledge on the anatomical structure of the fundus, these findings suggest an association of the short, middle and long fluorescence decay time to the retinal pigment epithelium, the retina, and connective tissue respectively.

  4. Short-wavelength luminescence in Ho{sup 3+}-doped KGd(WO{sub 4}){sub 2} crystals

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, M., E-mail: m.malinowski@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Kaczkan, M.; Stopinski, S.; Piramidowicz, R. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Majchrowski, A. [Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland)

    2009-12-15

    Emissions from the high-lying excited states, energy transfer and upconversion processes are investigated in Ho{sup 3+}-activated KGd(WO{sub 4}){sub 2} crystal. The spectral assignment based on time-resolved emission spectra allowed to identify various near ultra-violet (UV), blue and green emissions starting from the excited {sup 3}H{sub 5}, {sup 5}G{sub 4}, {sup 5}G{sub 5}, {sup 5}F{sub 3} and {sup 5}S{sub 2} levels. The temporal behavior of these transitions after pulsed excitation was analyzed as a function of temperature and holmium ions concentration. The shortening and nonexponentiality of the decays, observed with increasing activator concentrations, indicated cross-relaxation (CR) among the Ho{sup 3+} ions. Cross-relaxation rates were experimentally determined as a function of activator concentration and used to evaluate the values of the nearest-neighbor trapping rates X{sub 01} and to model the decays. It was observed that KGW, despite higher than in YAG maximum phonon energy of about 900 cm{sup -1}, is more efficient short-wavelength emitter than YAG. Examples of the excited-state absorption (ESA) and energy transfer (ET) mechanisms responsible for the upconverted, short-wavelength emissions were identified by analyzing fluorescence dynamics and possible energy resonances.

  5. Influence of wavelength on transient short-circuit current in polycrystalline silicon solar cells

    International Nuclear Information System (INIS)

    Ba, B.; Kane, M.

    1993-10-01

    The influence of the wavelength of a monochromatic illumination on transient short-circuit current in an n/p polycrystalline silicon part solar cell junction is investigated. A wavelength dependence in the initial part of the current decay is observed in the case of cells with moderate grain boundary effects. This influence is attenuated in polycrystalline cells with strong grain boundary activity. (author). 10 refs, 6 figs

  6. Prediction of Backscatter and Emissivity of Snow at Millimeter Wavelengths.

    Science.gov (United States)

    1980-01-01

    AD-AI16 9A MASSACHUISETTS IMST OF TECH CAMBRIDGE RESEARCH LAB OF-ETC F/6 17/9 PREDICTION OF BACKSCATTER AND EMISSIVITY OF SNOW AT MILLETER --ETC(U...emitting media such as snow. The emissivity in the Ray- leigh- Jeans approximation is then the microwave brightness tempera- ture T divided by an effective...resistivity, and thermal tempera- ture. Jean et al. (Reference 125) compared a theoretical expression for the total apparent temperature of a smooth surface

  7. Operational characteristics of the OMEGA short-wavelength laser fusion facility

    International Nuclear Information System (INIS)

    Soures, J.M.; Hutchison, R.; Jacobs, S.; McCrory, R.L.; Peck, R.; Seka, W.

    1984-01-01

    Twelve beams of the OMEGA, 24 beam direct-drive laser facility have been converted to 351-nm wavelength operation. The performance characteristics of this short-wavelength facility will be discussed. Beam-to-beam energy balance of +-2.3% and on-target energy, at 351-nm, in excess of 70 J per beam have been demonstrated. Long-term performance (>600 shots) of the system has been optimized by appropriate choice of index matching liquid, optical materials and coatings. The application of this system in direct-drive laser fusion experiments will be discussed

  8. Multi-photon ionization of atoms in intense short-wavelength radiation fields

    Science.gov (United States)

    Meyer, Michael

    2015-05-01

    The unprecedented characteristics of XUV and X-ray Free Electron Lasers (FELs) have stimulated numerous investigations focusing on the detailed understanding of fundamental photon-matter interactions in atoms and molecules. In particular, the high intensities (up to 106 W/cm2) giving rise to non-linear phenomena in the short wavelength regime. The basic phenomenology involves the production of highly charged ions via electron emission to which both sequential and direct multi-photon absorption processes contribute. The detailed investigation of the role and relative weight of these processes under different conditions (wavelength, pulse duration, intensity) is the key element for a comprehensive understanding of the ionization dynamics. Here the results of recent investigations are presented, performed at the FELs in Hamburg (FLASH) and Trieste (FERMI) on atomic systems with electronic structures of increasing complexity (Ar, Ne and Xe). Mainly, electron spectroscopy is used to obtain quantitative information about the relevance of various multi-photon ionization processes. For the case of Ar, a variety of processes including above threshold ionization (ATI) from 3p and 3s valence shells, direct 2p two-photon ionization and resonant 2p-4p two-photon excitations were observed and their role was quantitatively determined comparing the experimental ionization yields to ab-initio calculations of the cross sections for the multi-photon processes. Using Ar as a benchmark to prove the reliability of the combined experimental and theoretical approach, the more complex and intriguing case of Xe was studied. Especially, the analysis of the two-photon ATI from the Xe 4d shell reveals new insight into the character of the 4d giant resonance, which was unresolved in the linear one-photon regime. Finally, the influence of intense XUV radiation to the relaxation dynamics of the Ne 2s-3p resonance was investigated by angle-resolved electron spectroscopy, especially be observing

  9. Sensitivity of Heterointerfaces on Emission Wavelength in Quantum Cascade Lasers

    Science.gov (United States)

    2016-10-31

    thickness. To correct the composition, a secondary flow of the Al precursor was added during MOVPE growth to increase Al content in QCLs. The resulting...diluted 200 ppm in H2) was used as the n-type dopant. The growth temperature was 625 °C as measured by emissivity corrected optical pyrometrey. AlInAs and...Muraki, S. Fukatsu, Y. Shiraki, and R. Ito , "Surface segregation of In atoms during molecular beam epitaxy and its influence on the energy levels in

  10. Short-wavelength attenuated polychromatic white light during work at night : Limited melatonin suppression without substantial decline of alertness

    NARCIS (Netherlands)

    van de Werken, Maan; Giménez, Marina C; de Vries, Bonnie; Beersma, Domien G M; Gordijn, Marijke C M

    Exposure to light at night increases alertness, but light at night (especially short-wavelength light) also disrupts nocturnal physiology. Such disruption is thought to underlie medical problems for which shiftworkers have increased risk. In 33 male subjects we investigated whether short-wavelength

  11. Local instabilities in magnetized rotational flows: A short-wavelength approach

    OpenAIRE

    Kirillov, Oleg N.; Stefani, Frank; Fukumoto, Yasuhide

    2014-01-01

    We perform a local stability analysis of rotational flows in the presence of a constant vertical magnetic field and an azimuthal magnetic field with a general radial dependence. Employing the short-wavelength approximation we develop a unified framework for the investigation of the standard, the helical, and the azimuthal version of the magnetorotational instability, as well as of current-driven kink-type instabilities. Considering the viscous and resistive setup, our main focus is on the cas...

  12. Nonlinear-optical generation of short-wavelength radiation controlled by laser-induced interference structures

    International Nuclear Information System (INIS)

    Popov, A K; Kimberg, V V

    1998-01-01

    A study is reported of the combined influence of laser-induced resonances in the energy continuum, of splitting of discrete resonances in the field of several strong radiations, and of absorption of the initial and generated radiations on totally resonant parametric conversion to the short-wavelength range. It is shown that the radiation power can be increased considerably by interference processes involving quantum transitions. (nonlinear optical phenomena and devices)

  13. Continuously tunable sub-half-wavelength localization via coherent control of spontaneous emission

    International Nuclear Information System (INIS)

    Wang Fei; Tan Xin-Yu; Gong Cheng; Shi Wen-Xing

    2012-01-01

    We propose a continuously tunable method of sub-half-wavelength localization via the coherent control of the spontaneous emission of a four-level Y-type atomic system, which is coupled to three strong coupling fields including a standing-wave field together with a weak probe field. It is shown that the sub-half-wavelength atomic localization is realized for both resonance and off-resonance cases. Furthermore, by varying the probe detuning in succession, the positions of the two localization peaks are tuned continuously within a wide range of probe field frequencies, which provides convenience for the realization of sub-half-wavelength atomic localization experimentally

  14. Gamma-ray detection with an UV-enhanced photodiode and scintillation crystals emitting at short wavelengths

    International Nuclear Information System (INIS)

    Johansen, G.A.

    1997-01-01

    A low-noise ion implanted photodiode with high spectral response in the deep blue/UV region has been tested as read-out device for scintillation crystals with matching emission spectra (YAP(Ce), GSO(Ce), BGO and CsI(Tl)). This gamma-ray detector concept is attractive in many industrial applications where compactness, reliability and ambient temperature operation are important. The results show that the amount of detected scintillation light energy falls rapidly off as the wavelength of the scintillation light decreases. It is concluded that the dynamic spectral response of the photodiode, due to increasing carrier collection times, is considerably less than the DC response at short wavelengths. The diode is not useful in pulse mode operation with scintillation crystals emitting at wavelengths below about 400 nm. For read-out of CsI(Tl) with 661.6 keV gamma-radiation, however, the photodiode concept shows better energy resolution (7.1%) than other detectors. (orig.)

  15. Short-Wavelength Light Enhances Cortisol Awakening Response in Sleep-Restricted Adolescents

    Directory of Open Access Journals (Sweden)

    Mariana G. Figueiro

    2012-01-01

    Full Text Available Levels of cortisol, a hormone produced by the adrenal gland, follow a daily, 24-hour rhythm with concentrations reaching a minimum in the evening and a peak near rising time. In addition, cortisol levels exhibit a sharp peak in concentration within the first hour after waking; this is known as the cortisol awakening response (CAR. The present study is a secondary analysis of a larger study investigating the impact of short-wavelength (λmax≈470 nm light on CAR in adolescents who were sleep restricted. The study ran over the course of three overnight sessions, at least one week apart. The experimental sessions differed in terms of the light exposure scenarios experienced during the evening prior to sleeping in the laboratory and during the morning after waking from a 4.5-hour sleep opportunity. Eighteen adolescents aged 12–17 years were exposed to dim light or to 40 lux (0.401 W/m2 of 470-nm peaking light for 80 minutes after awakening. Saliva samples were collected every 20 minutes to assess CAR. Exposure to short-wavelength light in the morning significantly enhanced CAR compared to dim light. Morning exposure to short-wavelength light may be a simple, yet practical way to better prepare adolescents for an active day.

  16. Investigation of concept of efficient short wavelength laser. Quarterly progress report, 1 August 1978--31 October 1978

    Energy Technology Data Exchange (ETDEWEB)

    Piper, L.G.; Krech, R.H.; Pugh, E.R.; Taylor, R.L.

    1978-12-01

    A concept for the development of an efficient short wavelength laser based on a class of endoergic molecules-azides is being studied. One of these two laser-device experiments involves generating high concentrations of azide radicals in the thermal pyrolysis of solid, ionic azides, with the subsequent excitation of the N/sub 2/(B/sup 3/pi/sub g/) state from azide-radical recombination. Laser action would then take place upon the N/sub 2/(B/sup 3/pi/sub g/ - A/sup 3/Sigma/sup +//sub u/), first-postive transition. The second laser-demonstration experiment involves creating a high density of NCl(b/sup 1/Sigma/sup +/) state by uv photolysis of ClN/sub 3/. In this case laser emission is expected on the NCl(b/sup 1/Sigma/sup +/ ..-->.. X/sup 3/Sigma/sup -/) transition at 665 nm.

  17. Investigation of concept of efficient short wavelength laser. Quarterly progress report, 1 August 1978--31 October 1978

    International Nuclear Information System (INIS)

    Piper, L.G.; Krech, R.H.; Pugh, E.R.; Taylor, R.L.

    1978-01-01

    A concept for the development of an efficient short wavelength laser based on a class of endoergic molecules-azides is being studied. One of these two laser-device experiments involves generating high concentrations of azide radicals in the thermal pyrolysis of solid, ionic azides, with the subsequent excitation of the N 2 (B 3 pi/sub g/) state from azide-radical recombination. Laser action would then take place upon the N 2 (B 3 pi/sub g/ - A 3 Sigma + /sub u/), first-postive transition. The second laser-demonstration experiment involves creating a high density of NCl(b 1 Sigma + ) state by uv photolysis of ClN 3 . In this case laser emission is expected on the NCl(b 1 Sigma + → X 3 Sigma - ) transition at 665 nm

  18. Investigation of concept of efficient short wavelength laser. Quarterly progress report, 1 November 1978-31 January 1979

    Energy Technology Data Exchange (ETDEWEB)

    Krech, R.H.; Piper, L.G.; Pugh, E.R.; Taylor, R.L.

    1979-03-01

    A concept for the development of an efficient short wavelength laser based on a class of endoergic molecules-azides is being investigated. The first of two laser-device experiments involves generating high concentrations of azide radicals in the thermal pyrolysis of solid, ionic azides, with the subsequent excitation of the N/sub 2/(B/sup 3/..pi../sub g/) state from azide-radical recombination. Laser action would then take place upon the N/sub 2/(B/sup 3/..pi../sub g/-A/sup 3/..sigma../sup +//sub u/), first-positive transition. The second laser-demonstration experiment involves creating a high density of NCl(b/sup 1/..sigma../sup +/) state by uv photolysis of ClN/sub 3/. In this case laser emission is expected on the NCl(b/sup 1/..sigma../sup +/..-->..X/sup 3/..sigma../sup -/) transition at 665 nm.

  19. Extended short wavelength infrared HgCdTe detectors on silicon substrates

    Science.gov (United States)

    Park, J. H.; Hansel, D.; Mukhortova, A.; Chang, Y.; Kodama, R.; Zhao, J.; Velicu, S.; Aqariden, F.

    2016-09-01

    We report high-quality n-type extended short wavelength infrared (eSWIR) HgCdTe (cutoff wavelength 2.59 μm at 77 K) layers grown on three-inch diameter CdTe/Si substrates by molecular beam epitaxy (MBE). This material is used to fabricate test diodes and arrays with a planar device architecture using arsenic implantation to achieve p-type doping. We use different variations of a test structure with a guarded design to compensate for the lateral leakage current of traditional test diodes. These test diodes with guarded arrays characterize the electrical performance of the active 640 × 512 format, 15 μm pitch detector array.

  20. [Investigation of multi-wavelength effect during the measurement of UV-enhanced film's emission spectrum].

    Science.gov (United States)

    Liu, Meng; Ni, Zheng-ji; Zhang, Da-wei; Huang, Yuan-shen; Zhuang, Song-lin

    2009-09-01

    The UV-responsive detector is a dual-use device for civilian and military after the laser and IR-responsive sensors. Typical image sensor coated with a layer of down-convert frequency thin film on it's photosurface to enhance UV response is the key technology of enhancing UV-response. The UV-enhanced thin film was made in the experimental laboratory using the Zn2SiO4:Mn phosphor by spin coating method. Two peaks at 520 and 560 nm respectively in the emission spectrum of the UV-enhanced film were found by SP1702 spectrograph when the excitation wavelength was 260 and 280 nm. The peaks were found in the process of experiment of measuring and counting the quantum efficiency of UV-enhanced thin film. But the light peaks at 520 and 560 nm are not the emission light peaks by the exciting light of 260 and 280 nm. The reason why the light at 520 and 560 nm is not the emission light was analyzed based on the measurement principle of grating spectrograph. The reasons for the multi-wavelength of light overlaps during the measurement of emission spectrum were also discussed. And the equipment used to separate the overlapped different wavelengths was designed, which will be used to resolve the problem of the overlap of multi-wavelength.

  1. Short-wavelength free-electron laser sources and science: a review

    Science.gov (United States)

    Seddon, E. A.; Clarke, J. A.; Dunning, D. J.; Masciovecchio, C.; Milne, C. J.; Parmigiani, F.; Rugg, D.; Spence, J. C. H.; Thompson, N. R.; Ueda, K.; Vinko, S. M.; Wark, J. S.; Wurth, W.

    2017-11-01

    This review is focused on free-electron lasers (FELs) in the hard to soft x-ray regime. The aim is to provide newcomers to the area with insights into: the basic physics of FELs, the qualities of the radiation they produce, the challenges of transmitting that radiation to end users and the diversity of current scientific applications. Initial consideration is given to FEL theory in order to provide the foundation for discussion of FEL output properties and the technical challenges of short-wavelength FELs. This is followed by an overview of existing x-ray FEL facilities, future facilities and FEL frontiers. To provide a context for information in the above sections, a detailed comparison of the photon pulse characteristics of FEL sources with those of other sources of high brightness x-rays is made. A brief summary of FEL beamline design and photon diagnostics then precedes an overview of FEL scientific applications. Recent highlights are covered in sections on structural biology, atomic and molecular physics, photochemistry, non-linear spectroscopy, shock physics, solid density plasmas. A short industrial perspective is also included to emphasise potential in this area. Dedicated to John M J Madey (1943-2016) and Rodolfo Bonifacio (1940-2016) whose perception, drive and perseverance paved the way for the realisation and development of short-wavelength free-electron lasers.

  2. Optimization of a miniature short-wavelength infrared objective optics of a short-wavelength infrared to visible upconversion layer attached to a mobile-devices visible camera

    Science.gov (United States)

    Kadosh, Itai; Sarusi, Gabby

    2017-10-01

    The use of dual cameras in parallax in order to detect and create 3-D images in mobile devices has been increasing over the last few years. We propose a concept where the second camera will be operating in the short-wavelength infrared (SWIR-1300 to 1800 nm) and thus have night vision capability while preserving most of the other advantages of dual cameras in terms of depth and 3-D capabilities. In order to maintain commonality of the two cameras, we propose to attach to one of the cameras a SWIR to visible upconversion layer that will convert the SWIR image into a visible image. For this purpose, the fore optics (the objective lenses) should be redesigned for the SWIR spectral range and the additional upconversion layer, whose thickness is mobile device visible range camera sensor (the CMOS sensor). This paper presents such a SWIR objective optical design and optimization that is formed and fit mechanically to the visible objective design but with different lenses in order to maintain the commonality and as a proof-of-concept. Such a SWIR objective design is very challenging since it requires mimicking the original visible mobile camera lenses' sizes and the mechanical housing, so we can adhere to the visible optical and mechanical design. We present in depth a feasibility study and the overall optical system performance of such a SWIR mobile-device camera fore optics design.

  3. Integral equation based stability analysis of short wavelength drift modes in tokamaks

    International Nuclear Information System (INIS)

    Hirose, A.; Elia, M.

    2003-01-01

    Linear stability of electron skin-size drift modes in collisionless tokamak discharges has been investigated in terms of electromagnetic, kinetic integral equations in which neither ions nor electrons are assumed to be adiabatic. A slab-like ion temperature gradient mode persists in such a short wavelength regime. However, toroidicity has a strong stabilizing influence on this mode. In the electron branch, the toroidicity induced skin-size drift mode previously predicted in terms of local kinetic analysis has been recovered. The mode is driven by positive magnetic shear and strongly stabilized for negative shear. The corresponding mixing length anomalous thermal diffusivity exhibits favourable isotope dependence. (author)

  4. Two-dimensional sub-half-wavelength atom localization via controlled spontaneous emission.

    Science.gov (United States)

    Wan, Ren-Gang; Zhang, Tong-Yi

    2011-12-05

    We propose a scheme for two-dimensional (2D) atom localization based on the controlled spontaneous emission, in which the atom interacts with two orthogonal standing-wave fields. Due to the spatially dependent atom-field interaction, the position probability distribution of the atom can be directly determined by measuring the resulting spontaneously emission spectrum. The phase sensitive property of the atomic system leads to quenching of the spontaneous emission in some regions of the standing-waves, which significantly reduces the uncertainty in the position measurement of the atom. We find that the frequency measurement of the emitted light localizes the atom in half-wavelength domain. Especially the probability of finding the atom at a particular position can reach 100% when a photon with certain frequency is detected. By increasing the Rabi frequencies of the driving fields, such 2D sub-half-wavelength atom localization can acquire high spatial resolution.

  5. Short wavelength laser-plasma interaction experiments in a spherical geometry

    International Nuclear Information System (INIS)

    Keck, R.L.

    1984-01-01

    Short wavelength (250 to 500 nm) lasers should provide reduced fast electron preheat and increased laser-pellet coupling efficiency when used as laser fusion drivers. As part of an ongoing effort to study short wavelength laser plasm interaction, six beams of the 24 beam OMEGA Nd-glass laser system have been converted to operation at the third harmonic. This system is capable of providing in excess of 250 Joules of 351 nm light on spherical targets at intensities up to 2 x 10/sup 15/ W/cm/sup 2/. To date, experiments have been performed to study the uniformity of irradiation, laser absorption, fast electron production and preheat, energy transport within the target and underdense plasma instabilities. Both x-ray continuum measurements and Kα line measurements indicate that the absorption is dominated by inverse bremsstrahlung. Electron energy transport has been studied using x-ray burn-through and charge collector measurements. The results show that with 351 nm irradiation ablation pressures of order 100 Mbars are generated at intensities of 10/sup 15/ W/cm/sup 2/

  6. The opto-cryo-mechanical design of the short wavelength camera for the CCAT Observatory

    Science.gov (United States)

    Parshley, Stephen C.; Adams, Joseph; Nikola, Thomas; Stacey, Gordon J.

    2014-07-01

    The CCAT observatory is a 25-m class Gregorian telescope designed for submillimeter observations that will be deployed at Cerro Chajnantor (~5600 m) in the high Atacama Desert region of Chile. The Short Wavelength Camera (SWCam) for CCAT is an integral part of the observatory, enabling the study of star formation at high and low redshifts. SWCam will be a facility instrument, available at first light and operating in the telluric windows at wavelengths of 350, 450, and 850 μm. In order to trace the large curvature of the CCAT focal plane, and to suit the available instrument space, SWCam is divided into seven sub-cameras, each configured to a particular telluric window. A fully refractive optical design in each sub-camera will produce diffraction-limited images. The material of choice for the optical elements is silicon, due to its excellent transmission in the submillimeter and its high index of refraction, enabling thin lenses of a given power. The cryostat's vacuum windows double as the sub-cameras' field lenses and are ~30 cm in diameter. The other lenses are mounted at 4 K. The sub-cameras will share a single cryostat providing thermal intercepts at 80, 15, 4, 1 and 0.1 K, with cooling provided by pulse tube cryocoolers and a dilution refrigerator. The use of the intermediate temperature stage at 15 K minimizes the load at 4 K and reduces operating costs. We discuss our design requirements, specifications, key elements and expected performance of the optical, thermal and mechanical design for the short wavelength camera for CCAT.

  7. Lack of short-wavelength light during the school day delays dim light melatonin onset (DLMO) in middle school students.

    Science.gov (United States)

    Figueiro, Mariana G; Rea, Mark S

    2010-01-01

    Circadian timing affects sleep onset. Delayed sleep onset can reduce sleep duration in adolescents required to awake early for a fixed school schedule. The absence of short-wavelength ("blue") morning light, which helps entrain the circadian system, can hypothetically delay sleep onset and decrease sleep duration in adolescents. The goal of this study was to investigate whether removal of short-wavelength light during the morning hours delayed the onset of melatonin in young adults. Dim light melatonin onset (DLMO) was measured in eleven 8th-grade students before and after wearing orange glasses, which removed short-wavelength light, for a five-day school week. DLMO was significantly delayed (30 minutes) after the five-day intervention, demonstrating that short-wavelength light exposure during the day can be important for advancing circadian rhythms in students. Lack of short-wavelength light in the morning has been shown to delay the circadian clock in controlled laboratory conditions. The results presented here are the first to show, outside laboratory conditions, that removal of short-wavelength light in the morning hours can delay DLMO in 8th-grade students. These field data, consistent with results from controlled laboratory studies, are directly relevant to lighting practice in schools.

  8. Enhancement and wavelength-shifted emission of Cerenkov luminescence using multifunctional microspheres

    International Nuclear Information System (INIS)

    Li, Joanne; Dobrucki, Lawrence W; Marjanovic, Marina; Chaney, Eric J; Suslick, Kenneth S; Boppart, Stephen A

    2015-01-01

    Cerenkov luminescence (CL) imaging is a new molecular imaging modality that utilizes the photons emitted during radioactive decay when charged particles travel faster than the phase velocity of light in a dielectric medium. Here we present a novel agent to convert and increase CL emission at longer wavelengths using multimodal protein microspheres (MSs). The 64 Cu-labeled protein microspheres contain quantum dots (QDs) encapsulated within a high-refractive-index-oil core. Dark box imaging of the MSs was conducted to demonstrate the improvement in CL emission at longer wavelengths. To illustrate the versatile design of these MSs and the potential of CL in disease diagnosis, these MSs were utilized for in vitro cell targeting and ex vivo CL-excited QD fluorescence (CL-FL) imaging of atherosclerotic plaques in rats. It was shown that by utilizing both QDs and MSs with a high-refractive-index-oil core, the CL emission increases by four-fold at longer wavelengths. Furthermore, we demonstrate that these MSs generate both an in vivo and ex vivo contrast signal. The design concept of utilizing QDs and high-index core MSs may contribute to future developments of in vivo CL imaging. (paper)

  9. Investigation of concept of efficient short wavelength laser. Final technical report, April 1, 1977-July 31, 1979

    International Nuclear Information System (INIS)

    Piper, L.G.; Krech, R.H.; Pugh, E.; Taylor, R.L.

    1979-01-01

    The feasibility of producing an efficient, short wavelength, storage laser for ICF driven applications by making use of certain state-specific reactions of exoergic azide compounds has been investigated. The ultraviolet (approx. 300 nm) photolysis of gaseous ClN 3 produced prompt emission in the red, which was attributed to the efficient formation of ClN(b 1 Σ + ) with subsequent ClN(X reverse arrow b) fluorescence. Based on these results, a small-scale laser demonstration experiment was constructed using short duration Xe flash lamps as the photolytic source. The results of this latter experiment were negative. The most plausible explanation was that the flash lamps provided sufficient far-uv radiation to dissociate and/or ionize the ClN(b) produced in the primary photolytic step. In parallel, limited experiments were performed on the rapid pyrolysis of a solid, ionic azide, NaN 3 , to produce gaseous N 3 radicals and subsequent production of triplet N 2 molecules

  10. Ultra-high accuracy optical testing: creating diffraction-limited short-wavelength optical systems

    International Nuclear Information System (INIS)

    Goldberg, Kenneth A.; Naulleau, Patrick P.; Rekawa, Senajith B.; Denham, Paul E.; Liddle, J. Alexander; Gullikson, Eric M.; Jackson, KeithH.; Anderson, Erik H.; Taylor, John S.; Sommargren, Gary E.; Chapman, Henry N.; Phillion, Donald W.; Johnson, Michael; Barty, Anton; Soufli, Regina; Spiller, Eberhard A.; Walton, Christopher C.; Bajt, Sasa

    2005-01-01

    Since 1993, research in the fabrication of extreme ultraviolet (EUV) optical imaging systems, conducted at Lawrence Berkeley National Laboratory (LBNL) and Lawrence Livermore National Laboratory (LLNL), has produced the highest resolution optical systems ever made. We have pioneered the development of ultra-high-accuracy optical testing and alignment methods, working at extreme ultraviolet wavelengths, and pushing wavefront-measuring interferometry into the 2-20-nm wavelength range (60-600 eV). These coherent measurement techniques, including lateral shearing interferometry and phase-shifting point-diffraction interferometry (PS/PDI) have achieved RMS wavefront measurement accuracies of 0.5-1-(angstrom) and better for primary aberration terms, enabling the creation of diffraction-limited EUV optics. The measurement accuracy is established using careful null-testing procedures, and has been verified repeatedly through high-resolution imaging. We believe these methods are broadly applicable to the advancement of short-wavelength optical systems including space telescopes, microscope objectives, projection lenses, synchrotron beamline optics, diffractive and holographic optics, and more. Measurements have been performed on a tunable undulator beamline at LBNL's Advanced Light Source (ALS), optimized for high coherent flux; although many of these techniques should be adaptable to alternative ultraviolet, EUV, and soft x-ray light sources. To date, we have measured nine prototype all-reflective EUV optical systems with NA values between 0.08 and 0.30 (f/6.25 to f/1.67). These projection-imaging lenses were created for the semiconductor industry's advanced research in EUV photolithography, a technology slated for introduction in 2009-13. This paper reviews the methods used and our program's accomplishments to date

  11. Surface Variability of Short-wavelength Radiation and Temperature on Exoplanets around M Dwarfs

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xin; Tian, Feng [Ministry of Education Key Laboratory for Earth System Modeling, Department of Earth System Science, Tsinghua University, Beijing 100084 (China); Wang, Yuwei [Department of Atmospheric and Oceanic Sciences, McGill University, Montreal, QC H3A 0B9 (Canada); Dudhia, Jimy; Chen, Ming, E-mail: tianfengco@tsinghua.edu.cn [National Center for Atmospheric Research, Boulder, CO (United States)

    2017-03-10

    It is a common practice to use 3D General Circulation Models (GCM) with spatial resolution of a few hundred kilometers to simulate the climate of Earth-like exoplanets. The enhanced albedo effect of clouds is especially important for exoplanets in the habitable zones around M dwarfs that likely have fixed substellar regions and substantial cloud coverage. Here, we carry out mesoscale model simulations with 3 km spatial resolution driven by the initial and boundary conditions in a 3D GCM and find that it could significantly underestimate the spatial variability of both the incident short-wavelength radiation and the temperature at planet surface. Our findings suggest that mesoscale models with cloud-resolving capability be considered for future studies of exoplanet climate.

  12. Magneto-optical enhancement of TbFeCo/Al films at short wavelength

    International Nuclear Information System (INIS)

    Song, K.; Ito, H.; Naoe, M.

    1992-01-01

    In this paper, the bilayered films composed of magneto-optical (MO) amorphous Tb-Te-Co alloy and reflective Al layers were deposited successively on glass slide substrates without plasma exposure by using the facing targets sputtering system. The specimen films with the thickness of MO layer t MO below 5 nm showed apparent perpendicular magnetic anisotropy constant Ku of 2 to 3 x 10 6 erg/cm3 and rectangular Kerr loop. The specimen film with t MO of 14 nm took the Kerr rotation angle θ k as large as about 0.36 degree, at the wavelength λ as short as about 400 nm. These values of θ k is considerably larger than those of the bilayered films in the conventional MO media. Normally, the bilayered films with t MO above 50 nm took θ k of about 0.25 degree at θ k of 400 nm

  13. Temperature distribution and heat radiation of patterned surfaces at short wavelengths

    Science.gov (United States)

    Emig, Thorsten

    2017-05-01

    We analyze the equilibrium spatial distribution of surface temperatures of patterned surfaces. The surface is exposed to a constant external heat flux and has a fixed internal temperature that is coupled to the outside heat fluxes by finite heat conductivity across the surface. It is assumed that the temperatures are sufficiently high so that the thermal wavelength (a few microns at room temperature) is short compared to all geometric length scales of the surface patterns. Hence the radiosity method can be employed. A recursive multiple scattering method is developed that enables rapid convergence to equilibrium temperatures. While the temperature distributions show distinct dependence on the detailed surface shapes (cuboids and cylinder are studied), we demonstrate robust universal relations between the mean and the standard deviation of the temperature distributions and quantities that characterize overall geometric features of the surface shape.

  14. Emitted short wavelength infrared radiation for detection and monitoring of volcanic activity

    Science.gov (United States)

    Rothery, D. A.; Francis, P. W.; Wood, C. A.

    1988-01-01

    Thematic Mapper images from LANDSAT were used to monitor volcanoes. Achievements include: (1) the discovery of a magmatic precursor to the 16 Sept. 1986 eruption of Lascar, northern Chile, on images from Mar. and July 1985 and of continuing fumarolic activity after the eruption; (2) the detection of unreported major changes in the distribution of lava lakes on Erta'Ale, Ethiopia; and (3) the mapping of a halo of still-hot spatter surrounding a vent on Mount Erebus, Antarctica, on an image acquired 5 min after a minor eruption otherwise known only from seismic records. A spaceborne short wavelength infrared sensor for observing hot phenomena of volcanoes is proposed. A polar orbit is suggested.

  15. Efficient color-tunable multiexcitonic dual wavelength emission from Type II semiconductor tetrapods.

    Science.gov (United States)

    Wu, Wen-Ya; Li, Mingjie; Lian, Jie; Wu, Xiangyang; Yeow, Edwin K L; Jhon, Mark H; Chan, Yinthai

    2014-09-23

    We synthesized colloidal InP/ZnS seeded CdS tetrapods by harnessing the structural stability of the InP/ZnS seed nanocrystals at the high reaction temperatures needed to grow the CdS arms. Because of an unexpected Type II band alignment at the interface of the InP/ZnS core and CdS arms that enhanced the occurrence of radiative excitonic recombination in CdS, these tetrapods were found to be capable of exhibiting highly efficient multiexcitonic dual wavelength emission of equal intensity at spectrally distinct wavelengths of ∼485 and ∼675 nm. Additionally, the Type II InP/ZnS seeded CdS tetrapods displayed a wider range of pump-dependent emission color-tunability (from red to white to blue) within the context of a CIE 1931 chromaticity diagram and possessed higher photostability due to suppressed multiexcitonic Auger recombination when compared to conventional Type I CdSe seeded CdS tetrapods. By employing time-resolved spectroscopy measurements, we were able to attribute the wide emission color-tunability to the large valence band offset between InP and CdS. This work highlights the importance of band alignment in the synthetic design of semiconductor nanoheterostructures, which can exhibit color-tunable multiwavelength emission with high efficiency and photostability.

  16. Laser spectroscopy on atoms and ions using short-wavelength radiation

    International Nuclear Information System (INIS)

    Larsson, Joergen.

    1994-05-01

    Radiative properties and energy structures in atoms and ions have been investigated using UV/VUV radiation. In order to obtain radiation at short wavelengths, frequency mixing of pulsed laser radiation in crystals and gases has been performed using recently developed frequency-mixing schemes. To allow the study of radiative lifetimes shorter than the pulses from standard Q-switched lasers, different techniques have been used to obtain sufficiently short pulses. The Hanle effect has been employed following pulsed laser excitation for the same purpose. High-resolution spectroscopic techniques have been adapted for use with the broad-band, pulsed laser sources which are readily available in the UV/VUV spectral region. In order to investigate sources of radiation in the XUV and soft X-ray spectral regions, harmonic generation in rare gases has been studied. The generation of coherent radiation by the interaction between laser radiation and relativistic electrons in a synchrotron storage ring has also been investigated. 60 refs

  17. Ultrafast terawatt laser sources for high-field particle acceleration and short wavelength generation

    International Nuclear Information System (INIS)

    Downer, M.C.

    1996-01-01

    The Laser Sources working group concerned itself with recent advances in and future requirements for the development of laser sources relevant to high-energy physics (HEP) colliders, small scale accelerators, and the generation of short wave-length radiation. We heavily emphasized pulsed terawatt peak power laser sources for several reasons. First, their development over the past five years has been rapid and multi-faceted, and has made relativistic light intensity available to the advanced accelerator community, as well as the wider physics community, for the first time. Secondly, they have strongly impacted plasma-based accelerator research over the past two years, producing the first experimental demonstrations of the laser wakefield accelerator (LWFA) in both its resonantly-driven and self-modulated forms. Thirdly, their average power and wall-plug efficiency currently fall well short of projected requirements for future accelerators and other high average power applications, but show considerable promise for improving substantially over the next few years. A review of this rapidly emerging laser technology in the context of advanced accelerator research is therefore timely

  18. Multi-wavelength emission from 3C 66A: clues to its redshift and gamma-ray emission location

    International Nuclear Information System (INIS)

    Yan Da-Hai; Fan Zhong-Hui; Zhou Yao; Dai Ben-Zhong

    2013-01-01

    The quasi-simultaneous multi-wavelength emission of TeV blazar 3C 66A is studied by using a one-zone multi-component leptonic jet model. It is found that the quasi-simultaneous spectral energy distribution of 3C 66A can be well reproduced; in particular, the first three months of its average Fermi-LAT spectrum can be well reproduced by the synchrotron self-Compton component plus external Compton component of the broad line region (BLR). Clues to its redshift and gamma-ray emission location are obtained. The results indicate the following. (i) On the redshift: The theoretical intrinsic TeV spectra can be predicted by extrapolating the reproduced GeV spectra. Through comparing these extrapolated TeV spectra with the corrected observed TeV spectra from extragalactic background light, it is suggested that the redshift of 3C 66A could be between 0.1 and 0.3, with the most likely value being ∼ 0.2. (ii) On the gamma-ray emission location: To well reproduce the GeV emission of 3C 66A under different assumptions on the BLR, the gamma-ray emission region is always required to be beyond the inner zone of the BLR. The BLR absorption effect on gamma-ray emission confirms this point.

  19. TES arrays for the short wavelength band of the SAFARI instrument on SPICA

    Science.gov (United States)

    Khosropanah, P.; Hijmering, R.; Ridder, M.; Gao, J. R.; Morozov, D.; Mauskopf, P. D.; Trappe, N.; O'Sullivan, C.; Murphy, A.; Griffin, D.; Goldie, D.; Glowacka, D.; Withington, S.; Jackson, B. D.; Audley, M. D.; de Lange, G.

    2012-09-01

    SPICA is an infra-red (IR) telescope with a cryogenically cooled mirror (~5K) with three instruments on board, one of which is SAFARI that is an imaging Fourier Transform Spectrometer (FTS) with three bands covering the wavelength of 34-210 μm. We develop transition edge sensors (TES) array for short wavelength band (34-60 μm) of SAFARI. These are based on superconducting Ti/Au bilayer as TES bolometers with a Tc of about 105 mK and thin Ta film as IR absorbers on suspended silicon nitride (SiN) membranes. These membranes are supported by long and narrow SiN legs that act as weak thermal links between the TES and the bath. Previously an electrical noise equivalent power (NEP) of 4×10-19 W/√Hz was achieved for a single pixel of such detectors. As an intermediate step toward a full-size SAFARI array (43×43), we fabricated several 8×9 detector arrays. Here we describe the design and the outcome of the dark and optical tests of several of these devices. We achieved high yield (<93%) and high uniformity in terms of critical temperature (<5%) and normal resistance (7%) across the arrays. The measured dark NEPs are as low as 5×10-19 W/√Hz with a response time of about 1.4 ms at preferred operating bias point. The optical coupling is implemented using pyramidal horns array on the top and hemispherical cavity behind the chip that gives a measured total optical coupling efficiency of 30±7%.

  20. Correlated evolution of short wavelength sensitive photoreceptor sensitivity and color pattern in Lake Malawi cichlids

    Directory of Open Access Journals (Sweden)

    Michael J. Pauers

    2016-02-01

    Full Text Available For evolutionary ecologists, the holy grail of visual ecology is to establish an unambiguous link between photoreceptor sensitivity, the spectral environment, and the perception of specific visual stimuli (e.g., mates, food, predators, etc.. Due to the bright nuptial colors of the males, and the role female mate choice plays in their evolution, the haplochromine cichlid fishes of the African great lakes are favorite research subjects for such investigations. Despite this attention, current evidence is equivocal; while distinct correlations among photoreceptor sensitivity, photic environment, and male coloration exist in Lake Victorian haplochromines, attempts to find such correlations in Lake Malawian cichlids have failed. Lake Malawi haplochromines have a wide variability in their short-wavelength-sensitive photoreceptors, especially compared to their mid- and long-wavelength-sensitive photoreceptors; these cichlids also vary in the degree to which they express one of three basic color patterns (vertical bars, horizontal stripes, and solid patches of colors, each of which is likely used in a different form of communication. Thus, we hypothesize that, in these fishes, spectral sensitivity and color pattern have evolved in a correlated fashion to maximize visual communication; specifically, ultraviolet sensitivity should be found in vertically-barred species to promote ‘private’ communication, while striped species should be less likely to have ultraviolet sensitivity, since their color pattern carries ‘public’ information. Using phylogenetic independent contrasts, we found that barred species had strong sensitivity to ultraviolet wavelengths, but that striped species typically lacked sensitivity to ultraviolet light. Further, the only variable, even when environmental variables were simultaneously considered, that could predict ultraviolet sensitivity was color pattern. We also found that, using models of correlated evolution, color

  1. Controlling the emission wavelength in group III-V semiconductor laser diodes

    KAUST Repository

    Ooi, Boon S.

    2016-12-29

    Methods are provided for modifying the emission wavelength of a semiconductor quantum well laser diode, e.g. by blue shifting the emission wavelength. The methods can be applied to a variety of semiconductor quantum well laser diodes, e.g. group III-V semiconductor quantum wells. The group III-V semiconductor can include AlSb, AlAs, Aln, AlP, BN, GaSb, GaAs, GaN, GaP, InSb, InAs, InN, and InP, and group III-V ternary semiconductors alloys such as AlxGai.xAs. The methods can results in a blue shifting of about 20 meV to 350 meV, which can be used for example to make group III-V semiconductor quantum well laser diodes with an emission that is orange or yellow. Methods of making semiconductor quantum well laser diodes and semiconductor quantum well laser diodes made therefrom are also provided.

  2. Reactions of N2(A3Σ/sub u/+) and candidates for short wavelength lasers

    International Nuclear Information System (INIS)

    Setser, D.W.

    1987-01-01

    This proposal is a request for a one year renewal of a contract with the Univ. of California (Lawrence Livermore Laboratory). The proposed experiments are directed towards investigation of possible short-wavelength laser candidate molecules that can be pumped via excitation-transfer reactions with N 2 (A 3 Σ/sub u/ + ) molecules. We will continue our flowing-afterglow experiments to characterize the excitation-transfer collisions between N 2 (A) and promising acceptor diatomic molecules (radicals). We also will extend the studies to include excitation-transfer to Cd and to S atoms. For some chemical systems, a pulsed N 2 (A) source would be very convenient for kinetic measurements and we propose to develop a pulsed N 2 (A) source. During the first year, we have shown that the excitation-transfer reaction between N 2 (A) and SO(X) provides a possible laser candidate. Therefore, we propose to start a program to study the quenching and relaxation kinetics of the SO(A 3 PI) molecule, using pulsed laser excitation techniques to generate specific levels of SO(A 3 PI)

  3. Short wavelength infrared optical windows for evaluation of benign and malignant tissues

    Science.gov (United States)

    Sordillo, Diana C.; Sordillo, Laura A.; Sordillo, Peter P.; Shi, Lingyan; Alfano, Robert R.

    2017-04-01

    There are three short wavelength infrared (SWIR) optical windows outside the conventionally used first near-infrared (NIR) window (650 to 950 nm). They occur in the 1000- to 2500-nm range and may be considered second, third, and fourth NIR windows. The second (1100 to 1350 nm) and third windows (1600 to 1870 nm) are now being explored through label-free linear and multiphoton imaging. The fourth window (2100 to 2350 nm) has been mostly ignored because of water absorption and the absence of sensitive detectors and ultrafast lasers. With the advent of new technology, use of window IV is now possible. Absorption and scattering properties of light through breast and prostate cancer, bone, lipids, and intralipid solutions at these windows were investigated. We found that breast and prostate cancer and bone have longer total attenuation lengths at NIR windows III and IV, whereas fatty tissues and intralipid have longest lengths at windows II and III. Since collagen is the major chromophore at 2100 and 2350 nm, window IV could be especially valuable in evaluating cancers and boney tissues, whereas windows II and III may be more useful for tissues with high lipid content. SWIR windows may be utilized as additional optical tools for the evaluation of collagen in tissues.

  4. Short-wavelength ablation of polymers in the high-fluence regime

    International Nuclear Information System (INIS)

    Liberatore, Chiara; Juha, Libor; Vyšín, Ludek; Endo, Akira; Mocek, Tomas; Mann, Klaus; Müller, Matthias; Pina, Ladislav; Rocca, Jorge J

    2014-01-01

    Short-wavelength ablation of poly(1,4-phenylene ether-ether-sulfone) (PPEES) and poly(methyl methacrylate) (PMMA) was investigated using extreme ultraviolet (XUV) and soft x-ray (SXR) radiation from plasma-based sources. The initial experiment was performed with a 10 Hz desktop capillary-discharge XUV laser lasing at 46.9 nm. The XUV laser beam was focused onto the sample by a spherical mirror coated with a Si/Sc multilayer. The same materials were irradiated with 13.5 nm radiation emitted by plasmas produced by focusing an optical laser beam onto a xenon gas-puff target. A Schwarzschild focusing optics coated with a Mo/Si multilayer was installed at the source to achieve energy densities exceeding 0.1 J cm −2 in the tight focus. The existing experimental system at the Laser Laboratorium Göttingen was upgraded by implementing a 1.2 J driving laser. An increase of the SXR fluence was secured by improving the alignment technique. (paper)

  5. Ultraviolet and short wavelength visible light exposure: why ultraviolet protection alone is not adequate.

    Science.gov (United States)

    Reichow, Alan W; Citek, Karl; Edlich, Richard F

    2006-01-01

    The danger of exposure to ultraviolet (UV) radiation in both the natural environment and artificial occupational settings has long been recognized by national and international standards committees and worker safety agencies. There is an increasing body of literature that suggests that protection from UV exposure is not enough. Unprotected exposure to the short wavelengths of the visible spectrum, termed the "blue light hazard", is gaining acceptance as a true risk to long-term visual health. Global standards and experts in the field are now warning that those individuals who spend considerable time outdoors should seek sun filter eyewear with high impact resistant lenses that provide 100% UV filtration, high levels of blue light filtration, and full visual field lens/frame coverage as provided by high wrap eyewear. The Skin Cancer Foundation has endorsed certain sunglasses as "product[s]...effective [as] UV filter[s] for the eyes and surrounding skin". However, such endorsement does not necessarily mean that the eyewear meets all the protective needs for outdoor use. There are several brands that offer products with such protective characteristics. Performance sun eyewear by Nike Vision, available in both corrective and plano (nonprescription) forms, is one such brand incorporating these protective features.

  6. Random laser emission at dual wavelengths in a donor-acceptor dye mixture solution

    Directory of Open Access Journals (Sweden)

    Sunita Kedia

    Full Text Available The work was aimed to generate random laser emissions simultaneously at two wavelengths in a weakly scattering system containing mixture of binary dyes, rhodamine-B (Rh-B and oxazine-170 (O-170 dispersed with ZnO nano-particles serving as scattering centres. Random lasing performances for individual Rh-B dye were extensively studied for varying small signal gain/scatterer density and we found lasing threshold to significantly depend upon number density of dispersed nano-particles. In spite of inefficient pumping, we demonstrated possibility of random lasing in O-170 dye solution on account of resonance energy transfer from Rh-B dye which served as donor. At optimum concentrations of fluorophores and scatterer in dye mixture solution, incoherent random lasing was effectively attained simultaneously at two wavelengths centered 90 nm apart. Dual-emission intensities, lasing thresholds and rate of amplifications could be controlled and made equivalent for both donor and acceptor in dye mixture solution by appropriate choice of concentrations of dyes and scatterers. Keywords: Random lasing, Energy transfer, Rhodamine-B, Oxazine-170, Zinc oxide

  7. Modelling single shot damage thresholds of multilayer optics for high-intensity short-wavelength radiation sources

    NARCIS (Netherlands)

    Loch, R.A.; Sobierajski, R.; Louis, Eric; Bosgra, J.; Bosgra, J.; Bijkerk, Frederik

    2012-01-01

    The single shot damage thresholds of multilayer optics for highintensity short-wavelength radiation sources are theoretically investigated, using a model developed on the basis of experimental data obtained at the FLASH and LCLS free electron lasers. We compare the radiation hardness of commonly

  8. Short-Wavelength Infrared (SWIR) spectroscopy of low-grade metamorphic volcanic rocks of the Pilbara Craton

    NARCIS (Netherlands)

    Abweny, Mohammad S.; van Ruitenbeek, Frank J A; de Smeth, Boudewijn; Woldai, Tsehaie; van der Meer, Freek D.; Cudahy, Thomas; Zegers, Tanja; Blom, Jan Kees; Thuss, Barbara

    This paper shows the results of Short-Wavelength Infrared (SWIR) spectroscopy investigations of volcanic rocks sampled from low-grade metamorphic greenstone belts of the Archean Pilbara Craton in Western Australia. From the reflectance spectra a range of spectrally active minerals were identified,

  9. Short wavelength light filtering by the natural human lens and IOLs -- implications for entrainment of circadian rhythm

    DEFF Research Database (Denmark)

    Brøndsted, Adam Elias; Lundeman, Jesper Holm; Kessel, Line

    2013-01-01

    Photoentrainment of circadian rhythm begins with the stimulation of melanopsin containing retinal ganglion cells that respond directly to blue light. With age, the human lens becomes a strong colour filter attenuating transmission of short wavelengths. The purpose of the study was to examine the ...

  10. New Insight into Short-Wavelength Solar Wind Fluctuations from Vlasov Theory

    Science.gov (United States)

    Sahraoui, Fouad; Belmont, G.; Goldstein, M. L.

    2012-01-01

    The nature of solar wind (SW) turbulence below the proton gyroscale is a topic that is being investigated extensively nowadays, both theoretically and observationally. Although recent observations gave evidence of the dominance of kinetic Alfven waves (KAWs) at sub-ion scales with omega omega (sub ci)) is more relevant. Here, we study key properties of the short-wavelength plasma modes under limited, but realistic, SW conditions, Typically Beta(sub i) approx. > Beta (sub e) 1 and for high oblique angles of propagation 80 deg theory, we discuss the relevance of each plasma mode (fast, Bernstein, KAW, whistler) in carrying the energy cascade down to electron scales. We show, in particular, that the shear Alfven mode (known in the magnetohydrodynamic limit) extends at scales kappa rho (sub i) approx. > 1 to frequencies either larger or smaller than omega (sub ci), depending on the anisotropy kappa (parallel )/ kappa(perpendicular). This extension into small scales is more readily called whistler (omega > omega (sub ci)) or KAW (omega < omega (sub ci)) although the mode is essentially the same. This contrasts with the well-accepted idea that the whistler branch always develops as a continuation at high frequencies of the fast magnetosonic mode. We show, furthermore, that the whistler branch is more damped than the KAW one, which makes the latter the more relevant candidate to carry the energy cascade down to electron scales. We discuss how these new findings may facilitate resolution of the controversy concerning the nature of the small-scale turbulence, and we discuss the implications for present and future spacecraft wave measurements in the SW.

  11. Increasing robustness of indirect drive capsule designs against short wavelength hydrodynamic instabilities

    International Nuclear Information System (INIS)

    Haan, S.W.; Herrmann, M.C.; Dittrich, T.R.; Fetterman, A.J.; Marinak, M.M.; Munro, D.H.; Pollaine, S.M.; Salmonson, J.D.; Strobel, G.L.; Suter, L.J.

    2005-01-01

    Targets meant to achieve ignition on the National Ignition Facility (NIF) [J. A. Paisner, J. D. Boyes, S. A. Kumpan, W. H. Lowdermilk, and M. S. Sorem, Laser Focus World 30, 75 (1994)] have been redesigned and their performance simulated. Simulations indicate dramatically reduced growth of short wavelength hydrodynamic instabilities, resulting from two changes in the designs. First, better optimization results from systematic mapping of the ignition target performance over the parameter space of ablator and fuel thickness combinations, using techniques developed by one of us (Herrmann). After the space is mapped with one-dimensional simulations, exploration of it with two-dimensional simulations quantifies the dependence of instability growth on target dimensions. Low modes and high modes grow differently for different designs, allowing a trade-off of the two regimes of growth. Significant improvement in high-mode stability can be achieved, relative to previous designs, with only insignificant increase in low-mode growth. This procedure produces capsule designs that, in simulations, tolerate several times the surface roughness that could be tolerated by capsules optimized by older more heuristic techniques. Another significant reduction in instability growth, by another factor of several, is achieved with ablators with radially varying dopant. In this type of capsule the mid-Z dopant, which is needed in the ablator to minimize x-ray preheat at the ablator-ice interface, is optimally positioned within the ablator. A fabrication scenario for graded dopants already exists, using sputter coating to fabricate the ablator shell. We describe the systematics of these advances in capsule design, discuss the basis behind their improved performance, and summarize how this is affecting our plans for NIF ignition

  12. Eta Carinae: Linelist for the Emission Spectrum of the Weigelt Blobs in the 1700-10400Angstrom Wavelength Region

    Science.gov (United States)

    Zethson, T.; Johansson, S.; Hartman, H.; Gull, T. R.

    2011-01-01

    Aims. We present line identifications in the 1700 to 10400A region for the Weigelt Blobs B and D, located 0.1 to 0.3" NNW of Eta Carinae. The aim of this work is to characterize the behavior of these luminous, dense gas condensations in response to the broad maximum and short minimum states of Eta Carinae during its 5.54-year spectroscopic period. Methods. The observations were carried out during March 1998, the minimum spectrum, and in February 1999, early maximum spectrum, with the Hubble Space Telescope/Space Telescope Imaging Spectrograph (HST/STIS) from 1640 to 10400A using the 52"x0.1" aperture centered on Eta Carinae at position angle -28 degrees. Extractions of the reduced spectrum centered on Weigelt B and D, 0.28: in length along the slit, were used to identify the narrow, nebular emission lines, measure their wavelengths and estimate their fluxes. Results. A linelist of 1500 lines is presented for the maximum and minimum states of combined Weigelt blobs B and D. The spectra are dominated by emission lines from the iron-group elements, but include lines from lighter elements. They include parity permitted and forbidden lines. A number of lines are fluorescent lines pumped by H Ly alpha. Other lines show anomalous excitation.

  13. Photonic engineering of highly linearly polarized quantum dot emission at telecommunication wavelengths

    Science.gov (United States)

    Mrowiński, P.; Emmerling, M.; Schneider, C.; Reithmaier, J. P.; Misiewicz, J.; Höfling, S.; Sek, G.

    2018-04-01

    In this work, we discuss a method to control the polarization anisotropy of spontaneous emission from neutral excitons confined in quantum-dot-like nanostructures, namely single epitaxial InAs quantum dashes emitting at telecom wavelengths. The nanostructures are embedded inside lithographically defined, in-plane asymmetric photonic mesa structures, which generate polarization-dependent photonic confinement. First, we study the influence of the photonic confinement on the polarization anisotropy of the emission by photoluminescence spectroscopy, and we find evidence of different contributions to a degree of linear polarization (DOLP), i.e., from the quantum dash and the photonic mesa, in total giving rise to DOLP =0.85 . Then, we perform finite-difference time-domain simulations of photonic confinement, and we calculate the DOLP in a dipole approximation showing well-matched results for the established model. Furthermore, by using numerical calculations, we demonstrate several types of photonic confinements where highly linearly polarized emission with DOLP of about 0.9 is possible by controlling the position of a quantum emitter inside the photonic structure. Then, we elaborate on anisotropic quantum emitters allowing for exceeding DOLP =0.95 in an optimized case, and we discuss the ways towards efficient linearly polarized single photon source at telecom bands.

  14. Analysis of Saturn's Thermal Emission at 2.2-cm Wavelength: Spatial Distribution of Ammonia Vapor

    Science.gov (United States)

    Laraia, A. L.; Ingersoll, A. P.; Janssen, Michael A.; Gulkis, Samuel; Oyafuso, Fabiano A.; Allison, Michael D.

    2013-01-01

    This work focuses on determining the latitudinal structure of ammonia vapor in Saturn's cloud layer near 1.5 bars using the brightness temperature maps derived from the Cassini RADAR (Elachi et al., 2004) instrument, which works in a passive mode to measure thermal emission from Saturn at 2.2-cm wavelength. We perform an analysis of five brightness temperature maps that span epochs from 2005 to 2011, which are presented in a companion paper by Janssen et al. (2013a, this issue). The brightness temperature maps are representative of the spatial distribution of ammonia vapor, since ammonia gas is the only effective opacity source in Saturn's atmosphere at 2.2-cm wavelength. Relatively high brightness temperatures indicate relatively low ammonia relative humidity (RH), and vice versa. We compare the observed brightness temperatures to brightness temperatures computed using the Juno atmospheric microwave radiative transfer (JAMRT) program which includes both the means to calculate a tropospheric atmosphere model for Saturn and the means to carry out radiative transfer calculations at microwave frequencies. The reference atmosphere to which we compare has a 3x solar deep mixing ratio of ammonia (we use 1.352x10(exp -4) for the solar mixing ratio of ammonia vapor relative to H2; see Atreya, 2010) and is fully saturated above its cloud base. The maps are comprised of residual brightness temperatures-observed brightness temperature minus the model brightness temperature of the saturated atmosphere.

  15. Interband emission energy in a dilute nitride quaternary semiconductor quantum dot for longer wavelength applications

    Science.gov (United States)

    Mageshwari, P. Uma; Peter, A. John; Lee, Chang Woo; Duque, C. A.

    2016-07-01

    Excitonic properties are studied in a strained Ga1-xInxNyAs1-y/GaAs cylindrical quantum dot. The optimum condition for the desired band alignment for emitting wavelength 1.55 μm is investigated using band anticrossing model and the model solid theory. The band gap and the band discontinuities of a Ga1-xInxNyAs1-y/GaAs quantum dot on GaAs are computed with the geometrical confinement effect. The binding energy of the exciton, the oscillator strength and its radiative life time for the optimum condition are found taking into account the spatial confinement effect. The effects of geometrical confinement and the nitrogen incorporation on the interband emission energy are brought out. The result shows that the desired band alignment for emitting wavelength 1.55 μm is achieved for the inclusion of alloy contents, y=0.0554% and x=0.339% in Ga1-xInxNyAs1-y/GaAs quantum dot. And the incorporation of nitrogen and indium shows the red-shift and the geometrical confinement shows the blue-shift. And it can be applied for fibre optical communication networks.

  16. Action spectrum for photobleaching of human lenses by short wavelength visible irradiation

    DEFF Research Database (Denmark)

    Kessel, Line; Larsen, Michael

    2015-01-01

    transmission with increasing laser irradiation. CONCLUSIONS: For a 75 year old lens an effect corresponding to elimination of 15 years or more of optical ageing was obtained. This study of the spectral characteristics and intensity needed to bleach the human lens with single-photon laser effects found...... an action-spectrum peak at 420 nm tailing gradually off toward longer wavelengths and more steeply toward shorter wavelengths. The results may be used to guide experiments with two-photon bleaching....

  17. Short-term landfill methane emissions dependency on wind.

    Science.gov (United States)

    Delkash, Madjid; Zhou, Bowen; Han, Byunghyun; Chow, Fotini K; Rella, Chris W; Imhoff, Paul T

    2016-09-01

    Short-term (2-10h) variations of whole-landfill methane emissions have been observed in recent field studies using the tracer dilution method for emissions measurement. To investigate the cause of these variations, the tracer dilution method is applied using 1-min emissions measurements at Sandtown Landfill (Delaware, USA) for a 2-h measurement period. An atmospheric dispersion model is developed for this field test site, which is the first application of such modeling to evaluate atmospheric effects on gas plume transport from landfills. The model is used to examine three possible causes of observed temporal emissions variability: temporal variability of surface wind speed affecting whole landfill emissions, spatial variability of emissions due to local wind speed variations, and misaligned tracer gas release and methane emissions locations. At this site, atmospheric modeling indicates that variation in tracer dilution method emissions measurements may be caused by whole-landfill emissions variation with wind speed. Field data collected over the time period of the atmospheric model simulations corroborate this result: methane emissions are correlated with wind speed on the landfill surface with R(2)=0.51 for data 2.5m above ground, or R(2)=0.55 using data 85m above ground, with emissions increasing by up to a factor of 2 for an approximately 30% increase in wind speed. Although the atmospheric modeling and field test are conducted at a single landfill, the results suggest that wind-induced emissions may affect tracer dilution method emissions measurements at other landfills. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. A cure for the blues: opsin duplication and subfunctionalization for short-wavelength sensitivity in jewel beetles (Coleoptera: Buprestidae).

    Science.gov (United States)

    Lord, Nathan P; Plimpton, Rebecca L; Sharkey, Camilla R; Suvorov, Anton; Lelito, Jonathan P; Willardson, Barry M; Bybee, Seth M

    2016-05-18

    Arthropods have received much attention as a model for studying opsin evolution in invertebrates. Yet, relatively few studies have investigated the diversity of opsin proteins that underlie spectral sensitivity of the visual pigments within the diverse beetles (Insecta: Coleoptera). Previous work has demonstrated that beetles appear to lack the short-wavelength-sensitive (SWS) opsin class that typically confers sensitivity to the "blue" region of the light spectrum. However, this is contrary to established physiological data in a number of Coleoptera. To explore potential adaptations at the molecular level that may compensate for the loss of the SWS opsin, we carried out an exploration of the opsin proteins within a group of beetles (Buprestidae) where short-wave sensitivity has been demonstrated. RNA-seq data were generated to identify opsin proteins from nine taxa comprising six buprestid species (including three male/female pairs) across four subfamilies. Structural analyses of recovered opsins were conducted and compared to opsin sequences in other insects across the main opsin classes-ultraviolet, short-wavelength, and long-wavelength. All nine buprestids were found to express two opsin copies in each of the ultraviolet and long-wavelength classes, contrary to the single copies recovered in all other molecular studies of adult beetle opsin expression. No SWS opsin class was recovered. Furthermore, the male Agrilus planipennis (emerald ash borer-EAB) expressed a third LWS opsin at low levels that is presumed to be a larval copy. Subsequent homology and structural analyses identified multiple amino acid substitutions in the UVS and LWS copies that could confer short-wavelength sensitivity. This work is the first to compare expressed opsin genes against known electrophysiological data that demonstrate multiple peak sensitivities in Coleoptera. We report the first instance of opsin duplication in adult beetles, which occurs in both the UVS and LWS opsin classes

  19. The Peculiar Binary System AE Aquarii from its Characteristic Multi-wavelength Emission

    Directory of Open Access Journals (Sweden)

    Oruru B.

    2014-01-01

    Full Text Available The multi-wavelength properties of the novalike variable system AE Aquarii are discussed in terms of the interaction between the accretion inflow from a late-type main sequence star and the magnetosphere of a fast rotating white dwarf. This results in an efficient magnetospheric propeller process and particle acceleration. The spin-down of the white dwarf at a period rate of 5.64×10−14 s s−1 results in a huge spin-down luminosity of Ls−d ≃ 6 10×33 erg s−1. Hence, the observed non-thermal hard X-ray emission and VHE and TeV gamma-ray emission may suggest that AE Aquarii can be placed in the category of spin-powered pulsars. Besides, observed hard X-ray luminosity of LX,hard ≤ 5 × 1030 erg s−1 constitutes 0.1 % of the total spin-down luminosity of the white dwarf. This paper will discuss some recent theoretical studies and data analysis of the system.

  20. Monolithic photonic integration for visible and short near-infrared wavelengths: technologies and platforms for bio and life science applications

    Science.gov (United States)

    Porcel, Marco A. G.; Artundo, Iñigo; Domenech, J. David; Geuzebroek, Douwe; Sunarto, Rino; Hoofman, Romano

    2018-04-01

    This tutorial aims to provide a general overview on the state-of-the-art of photonic integrated circuits (PICs) in the visible and short near-infrared (NIR) wavelength ranges, mostly focusing in silicon nitride (SiN) substrates, and a guide to the necessary steps in the design toward the fabrication of such PICs. The focus is put on bio- and life sciences, given the adequacy and, thus, a large number of applications in this field.

  1. Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

    International Nuclear Information System (INIS)

    McConnell, Gail; Riis, Erling

    2004-01-01

    We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM

  2. Study of short wavelength turbulence in dense plasmas. Final technical report, September 8, 1981-August 7, 1983

    International Nuclear Information System (INIS)

    Chen, F.F.; Joshi, C.

    1983-10-01

    The work includes studies of four topics: (1) Thomson scattering from short wavelength density fluctuations from laser excited plasmas from solid targets; (2) studies of SBS driven ion acoustic waves and it's harmonics in underdense plasmas; (3) studies of optical mixing excitation of electron plasma waves (high frequency density fluctuations) in theta pinch plasma; and (4) computational studies of high frequency wave excitation by intense laser beams in plasmas

  3. Laser spectroscopy of the products of photoevaporation with a short-wavelength (λ = 193 nm) excimer laser

    International Nuclear Information System (INIS)

    Gochelashvili, K S; Zemskov, M E; Evdokimova, O N; Mikhkel'soo, V T; Prokhorov, A M

    1999-01-01

    An excimer laser spectrometer was designed and constructed. It consists of a high-vacuum interaction chamber, a short-wavelength (λ = 193 nm) excimer ArF laser used for evaporation, a probe dye laser pumped by an XeCl excimer laser, and a system for recording a laser-induced fluorescence signal. This spectrometer was used to investigate nonthermal mechanisms of photoevaporation of a number of wide-gap dielectrics. (laser applications and other topics in quantum electronics)

  4. Emission intensity in New Zealand manufacturing and the short-run impacts of emissions pricing

    International Nuclear Information System (INIS)

    Bartleet, Matthew; Iyer, Kris; Numan-Parsons, Elisabeth

    2010-01-01

    This paper reports the greenhouse gas (GHG) emission intensity of the New Zealand (NZ) manufacturing sector at a combination of industry group and class levels (sub-sectors). The short-run impacts of a price on emissions are investigated with a focus on exporting activities. Sub-sectors that could be materially impacted by an expected range of emissions prices accounted for slightly over 9% of national gross domestic product. It is found that there is much variability of emission intensity within manufacturing and even within sub-sectors. An assessment of trade intensities further indicates that several emissions-intensive activities are also export-intensive. These activities are at most risk of losing competitiveness in the short-run if they are subjected to a price on GHG emissions that their competitors in other countries are not. Emissions reduction policies must take account of trade competitiveness imperatives if NZ is to meet its international GHG emissions target while maintaining manufacturing sector competitiveness. - Research Highlights: →Estimates initial short-term competitiveness impacts of ETS on NZ manufacturing. →Materiality of impacts determined based on firm level emissions and export intensity. →Results suggest that food processing sub-sectors are likely to be most impacted. →Iron and steel processing, and paper and pulp manufacture are impacted as well. →Cumulative GDP share of materially affected sub-sectors slightly over 9%.

  5. Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

    Science.gov (United States)

    Faghihi, M.; Scheffel, J.

    1987-12-01

    The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for P > P and large β

  6. Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

    International Nuclear Information System (INIS)

    Faghihi, M.; Schefffel, J.

    1987-01-01

    The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m ≥ 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for Psub(perpendicular) > Psub(parallel) and large βsub(perpendicular). (author)

  7. Short-Term Power Plant GHG Emissions Forecasting Model

    International Nuclear Information System (INIS)

    Vidovic, D.

    2016-01-01

    In 2010, the share of greenhouse gas (GHG) emissions from power generation in the total emissions at the global level was about 25 percent. From January 1st, 2013 Croatian facilities have been involved in the European Union Emissions Trading System (EU ETS). The share of the ETS sector in total GHG emissions in Croatia in 2012 was about 30 percent, where power plants and heat generation facilities contributed to almost 50 percent. Since 2013 power plants are obliged to purchase all emission allowances. The paper describes the short-term climate forecasting model of greenhouse gas emissions from power plants while covering the daily load diagram of the system. Forecasting is done on an hourly domain typically for one day, it is possible and more days ahead. Forecasting GHG emissions in this way would enable power plant operators to purchase additional or sell surplus allowances on the market at the time. Example that describes the operation of the above mentioned forecasting model is given at the end of the paper.(author).

  8. Group III nitride semiconductors for short wavelength light-emitting devices

    Science.gov (United States)

    Orton, J. W.; Foxon, C. T.

    1998-01-01

    The group III nitrides (AlN, GaN and InN) represent an important trio of semiconductors because of their direct band gaps which span the range 1.95-6.2 eV, including the whole of the visible region and extending well out into the ultraviolet (UV) range. They form a complete series of ternary alloys which, in principle, makes available any band gap within this range and the fact that they also generate efficient luminescence has been the main driving force for their recent technological development. High brightness visible light-emitting diodes (LEDs) are now commercially available, a development which has transformed the market for LED-based full colour displays and which has opened the way to many other applications, such as in traffic lights and efficient low voltage, flat panel white light sources. Continuously operating UV laser diodes have also been demonstrated in the laboratory, exciting tremendous interest for high-density optical storage systems, UV lithography and projection displays. In a remarkably short space of time, the nitrides have therefore caught up with and, in some ways, surpassed the wide band gap II-VI compounds (ZnCdSSe) as materials for short wavelength optoelectronic devices. The purpose of this paper is to review these developments and to provide essential background material in the form of the structural, electronic and optical properties of the nitrides, relevant to these applications. We have been guided by the fact that the devices so far available are based on the binary compound GaN (which is relatively well developed at the present time), together with the ternary alloys AlGaN and InGaN, containing modest amounts of Al or In. We therefore concentrate, to a considerable extent, on the properties of GaN, then introduce those of the alloys as appropriate, emphasizing their use in the formation of the heterostructures employed in devices. The nitrides crystallize preferentially in the hexagonal wurtzite structure and devices have so

  9. Investigation of black and brown carbon multiple-wavelength-dependent light absorption from biomass and fossil fuel combustion source emissions

    Science.gov (United States)

    Michael R. Olson; Mercedes Victoria Garcia; Michael A. Robinson; Paul Van Rooy; Mark A. Dietenberger; Michael Bergin; James Jay Schauer

    2015-01-01

    Quantification of the black carbon (BC) and brown carbon (BrC) components of source emissions is critical to understanding the impact combustion aerosols have on atmospheric light absorption. Multiple-wavelength absorption was measured from fuels including wood, agricultural biomass, coals, plant matter, and petroleum distillates in controlled combustion settings....

  10. Stability of short-axial-wavelength internal kink modes of an anisotropic plasma

    Energy Technology Data Exchange (ETDEWEB)

    Faghihi, M.; Schefffel, J.

    1987-12-01

    The double adiabatic equations are used to study the stability of a cylindrical Z-pinch with respect to small axial wavelength, internal kink (m greater than or equal to 1) modes. It is found that marginally (ideally) unstable, isotropic equilibria are stabilized. Also, constant-current-density equilibria can be stabilized for Psub(perpendicular) > Psub(parallel) and large ..beta..sub(perpendicular).

  11. Is there an unknown risk for short-wavelength visible laser radiation?

    Energy Technology Data Exchange (ETDEWEB)

    Reidenbach, Hans-Dieter; Beckmann, Dirk; Al Ghouz, Imene; Dollinger, Klaus [Fachhochschule Koeln (Germany). Forschungsbereich Medizintechnik und Nichtionisierende Strahlung; Ott, Guenter [Bundesanstalt fuer Arbeitsschutz und Arbeitsmedizin (BAuA), Dortmund (Germany); Brose, Martin [Berufsgenossenschaft Energie Textil Elektro Medienerzeugnisse (BG ETEM), Koeln (Germany)

    2013-09-01

    A specially designed test apparatus was used in the investigation on temporary blinding. During provisional tests, exposure had been carried out with different wavelengths, power settings and exposure durations. One subject familiar to the effects of temporary blinding experienced an unusual effect, which lasted a long period of time. Concerning that this effect is not known enough to be considered in safety regulations, make it important to publish this report. (orig.)

  12. Excitation and emission wavelength ratiometric cyanide-sensitive probes for physiological sensing.

    Science.gov (United States)

    Badugu, Ramachandram; Lakowicz, Joseph R; Geddes, Chris D

    2004-04-01

    We characterize three new fluorescent probes that show both spectral shifts and intensity changes in the presence of aqueous cyanide, allowing for both excitation and fluorescence emission wavelength ratiometric and colorimetric sensing. The relatively high binding constants of the probes for cyanide enables a distinct colorimetric change to be visually observed with as little as 10 microM cyanide. The response of the new probes is based on the ability of the boronic acid group to interact with the CN(-) anion, changing from the neutral form of the boronic acid group R-B(OH)(2) to the anionic R-B(-)(OH)3 form, which is an electron-donating group. The presence of an electron-deficient quaternary heterocyclic nitrogen center and a strong electron-donating amino group in the 6 position on the quinolinium backbone provides for the spectral changes observed upon CN(-) complexation. We have determined the binding constants for the ortho-, meta-, and para-boronic acid probes to be 0.12, 0.17, and 0.14 microM(-3). In addition we have synthesized a control compound that does not contain the boronic acid moiety, allowing for structural comparisons and a rationale for the sensing mechanism to be made. Finally we show that the affinity for monosaccharides, such as glucose or fructose, is relatively low as compared to that for cyanide, enabling the potential detection of cyanide in physiologies up to lethal levels.

  13. Long-wavelength stimulated emission and carrier lifetimes in HgCdTe-based waveguide structures with quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Rumyantsev, V. V., E-mail: rumyantsev@ipm.sci-nnov.ru; Fadeev, M. A.; Morozov, S. V.; Dubinov, A. A.; Kudryavtsev, K. E.; Kadykov, A. M. [Russian Academy of Sciences, Institute for Physics of Microstructures (Russian Federation); Tuzov, I. V. [Lobachevsky State University of Nizhny Novgorod (NNSU) (Russian Federation); Dvoretskii, S. A.; Mikhailov, N. N. [Russian Academy of Sciences, Institute for Semiconductor Physics, Siberian Branch (Russian Federation); Gavrilenko, V. I. [Novosibirsk State University (Russian Federation); Teppe, F. [Universite Montpellier II, Laboratoire Charles Coulomb (L2C) (France)

    2016-12-15

    The interband photoconductivity and photoluminescence in narrow-gap HgCdTe-based waveguide structures with quantum wells (QWs) (designed for long-wavelength stimulated emission under optical pumping) are investigated. The photoconductivity relaxation times in n-type structures reach several microseconds, due to which stimulated emission at a wavelength of 10.2 μm occurs at a low threshold pump intensity (~100 W/cm{sup 2}) at 20 K. In the p-type structures obtained by annealing (to increase the mercury vacancy concentration), even spontaneous emission from the QWs is not detected because of a dramatic decrease in the carrier lifetime with respect to Shockley–Read–Hall nonradiative recombination.

  14. Intense, stable and excitation wavelength-independent photoluminescence emission in the blue-violet region from phosphorene quantum dots

    Science.gov (United States)

    Ge, Shuaipeng; Zhang, Lisheng; Wang, Peijie; Fang, Yan

    2016-01-01

    Nanoscale phosphorene quantum dots (PQDs) with few-layer structures were fabricated by pulsed laser ablation of a bulk black phosphorus target in diethyl ether. An intense and stable photoluminescence (PL) emission of the PQDs in the blue-violet wavelength region is clearly observed for the first time, which is attributed to electronic transitions from the lowest unoccupied molecular orbital (LUMO) to the highest occupied molecular orbital (HOMO) and occupied molecular orbitals below the HOMO (H-1, H-2), respectively. Surprisingly, the PL emission peak positions of the PQDs are not red-shifted with progressively longer excitation wavelengths, which is in contrast to the cases of graphene and molybdenum disulphide quantum dots. This excitation wavelength-independence is derived from the saturated passivation on the periphery and surfaces of the PQDs by large numbers of electron-donating functional groups which cause the electron density on the PQDs to be dramatically increased and the band gap to be insensitive to the quantum size effect in the PQDs. This work suggests that PQDs with intense, stable and excitation wavelength-independent PL emission in the blue-violet region have a potential application as semiconductor-based blue-violet light irradiation sources. PMID:27265198

  15. Recovery Of Short Wavelength Geophysical Signals With Future Delay-Doppler Altimeters (Cryosat Ii And Sentinel Type)

    DEFF Research Database (Denmark)

    Andersen, Ole Baltazar

    2010-01-01

    altimetry: Factor of 20 improvements in along track resolution. An along-track footprint length that does not vary with wave height (sea state). Twice the precision in sea surface height measurements / sea surface slope measurements. These improvements are studied with respect to retrieval of short...... wavelength geophysical signal related to mainly bathymetric features. The combination of upward continuation from the sea bottom and smoothing the altimeter observations resulted in the best recovery of geophysical signal for simulated 5-Hz DD observations. Simulations carried out in this investigation...

  16. Paraconductivity of three-dimensional amorphous superconductors: evidence for a short-wavelength cutoff in the fluctuation spectrum

    International Nuclear Information System (INIS)

    Johnson, W.L.

    1977-10-01

    Measurements of the temperature dependence and magnetic field dependence of the paraconductivity of a three dimensional amorphous superconductor are presented. The data are analyzed in terms of several current theories and are found to give good agreement for low fields and temperatures near T/sub c/. The paraconductivity falls well below predicted theoretical values in the high temperature and high field limits. This is attributed to the reduced role of high wavevector contributions to the paraconductivity. It is shown that the introduction of a short wavelength cutoff in the theoretical fluctuation spectrum provides a phenomelogical account of the discrepancy between theory and experiment

  17. Lasing at short wavelength in a capillary discharge and in a dense Z-pinch

    International Nuclear Information System (INIS)

    Kunze, H.-J.; Glenzer, S.; Steden, C.; Wieschebrink, H. T.; Koshelev, K. N.; Uskov, D.

    1995-01-01

    Results on the emission of the CVI Balmer-α transition obtained with a fast capillary discharge are summarized, and a model is discussed, which explains the observations as result of fast ions produced by a m=0 instabililty and charge exchange with CIII ions in the cold plasma region. Plasmas of large dimensions were produced in the gas-liner pinch discharge, and the emission of the 4f-3d transition has been studied in CIV, NV, OVI, and FVII. Amplification is seen on the transition in OVI and FVII

  18. AlGaN-based laser diodes for the short-wavelength ultraviolet region

    International Nuclear Information System (INIS)

    Yoshida, Harumasa; Kuwabara, Masakazu; Yamashita, Yoji; Takagi, Yasufumi; Uchiyama, Kazuya; Kan, Hirofumi

    2009-01-01

    We have demonstrated the room-temperature operation of GaN/AlGaN and indium-free AlGaN multiple-quantum-well (MQW) laser diodes under the pulsed-current mode. We have successfully grown low-dislocation-density AlGaN films with AlN mole fractions of 20 and 30% on sapphire substrates using the hetero-facet-controlled epitaxial lateral overgrowth (hetero-FACELO) method. GaN/AlGaN and AlGaN MQW laser diodes have been fabricated on the low-dislocation-density Al 0.2 Ga 0.8 N and Al 0.3 Ga 0.7 N films, respectively. The GaN/AlGaN MQW laser diodes lased at a peak wavelength ranging between 359.6 and 354.4 nm. A threshold current density of 8 kA cm -2 , an output power as high as 80 mW and a differential external quantum efficiency (DEQE) of 17.4% have been achieved. The AlGaN MQW laser diodes lased at a peak wavelength down to 336.0 nm far beyond the GaN band gap. For the GaN/AlGaN MQW laser diodes, the modal gain coefficient and the optical internal loss are estimated to be 4.7±0.6 cm kA -1 and 10.6±2.7 cm -1 , respectively. We have observed that the characteristic temperature T 0 ranges from 132 to 89 K and DEQE shows an almost stable tendency with increase of temperature. A temperature coefficient of 0.049 nm K -1 is also found for the GaN/AlGaN MQW laser diode. The results for the AlGaN-based laser diodes grown on high-quality AlGaN films presented here will be essential for the future development of laser diodes emitting much shorter wavelengths.

  19. Double pulse laser induced breakdown spectroscopy: Experimental study of lead emission intensity dependence on the wavelengths and sample matrix

    Energy Technology Data Exchange (ETDEWEB)

    Piscitelli S, V; Martinez L, M A; Fernandez C, A J [Laboratorio de Espectroscopia Laser, Escuela de Quimica, Facultad de Ciencias, Universidad Central de Venezuela, Caracas, DC 1020 (Venezuela, Bolivarian Republic of); Gonzalez, J J; Mao, X L [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Russo, R.E. [Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)], E-mail: RERusso@lbl.gov

    2009-02-15

    Lead (Pb) emission intensity (atomic line 405.78 nm) dependence on the sample matrix (metal alloy) was studied by means of collinear double pulse (DP)-laser induced breakdown spectroscopy (LIBS). The measurement of the emission intensity produced by three different wavelength combinations (i.e. I:532 nm-II:1064 nm, I:532 nm-II:532 nm, and I:532 nm-II:355 nm) from three series of standard reference materials showed that the lead atomic line 405.78 nm emission intensity was dependent on the sample matrix for all the combination of wavelengths, however reduced dependency was found for the wavelength combination I:532 nm-II:355 nm. Two series of standard reference materials from the National Institute of Standards and Technology (NIST) and one series from the British Chemical Standards (BCS) were used for these experiments. Calibration curves for lead ablated from NIST 626-630 ('Zn{sub 95}Al{sub 4}Cu{sub 1}') provided higher sensitivity (slope) than those calibration curves produced from NIST 1737-1741 ('Zn{sub 99.5}Al{sub 0.5}') and with the series BCS 551-556 ('Cu{sub 87}Sn{sub 11}'). Similar trends between lead emission intensity (calibration curve sensitivities) and reported variations in plasma temperatures caused by the differing ionization potentials of the major and minor elements in these samples were established.

  20. Emission channeling lattice location experiments with short-lived isotopes

    CERN Multimedia

    Wahl, U; Ronning, C R

    2007-01-01

    Emission channeling with position-sensitive detectors is a well-established technique at ISOLDE for studying the lattice location of radioactive impurities implanted into single crystals. In the case of electron emitting isotopes, however, due to count rate and noise-related limitations of the detection systems, the technique was restricted to isotopes with half lives above 6 h and electron energies above 40 keV. Recently, major technical developments have been realized and new equipment has been acquired which has allowed these limitations to be overcome and made feasible electron emission channeling experiments with short-lived isotopes and at low electron energies.\\\\ As first application, making use of two new on-line emission channeling setups at ISOLDE, we propose to investigate the lattice location of the transition metals Ni (2.5 h) and Co (1.6 h) in semiconductors, in particular in ZnO and GaN, by means of on-line $\\beta^{-}$-emission channeling experiments. In addition, we would like to study the lat...

  1. Efficient soft x-ray generation in short wavelength laser produced plasmas

    International Nuclear Information System (INIS)

    Mochizuki, T.; Yamanaka, C.

    1987-01-01

    Intense x-ray generation in 1.053, 0.53, 0.26 μm laser-produced plasma has been investigated in the photon energy range of 0.1 to 3keV. The x-ray spectrum is found to have several humps which move to the higher energy side as the atomic number of the target increases. This atomic dependence is explained by a semi-Moseley's law and allows us to predict a target material most suitable for generating the photons of desired energies. Conversion efficiencies of 1.5 -- 3keV x-rays are obtained also as a function of laser wavelength at the intensity of 10/sup 13/W/cm/sup 2/. The conversion efficiency of keV x rays has been enhanced by a factor of 2 -- 3 with a controlled prepulse laser. From the semi-Moseley's law we find that cryogenic targets using either Xe or Kr in a liquid or solid phase may be most useful for a number of applications because they radiate 1 -- 3 keV x rays efficiently and never deposit on the x-ray optical components and the objects to be exposed

  2. Atomic layer deposition of absorbing thin films on nanostructured electrodes for short-wavelength infrared photosensing

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Jixian; Sutherland, Brandon R.; Hoogland, Sjoerd; Fan, Fengjia; Sargent, Edward H., E-mail: ted.sargent@utoronto.ca [Department of Electrical and Computer Engineering, University of Toronto, 10 King' s College Road, Toronto, Ontario M5S 3G4 (Canada); Kinge, Sachin [Advanced Technology, Materials and Research, Research and Development, Hoge Wei 33- Toyota Technical Centre, B-1930 Zaventem (Belgium)

    2015-10-12

    Atomic layer deposition (ALD), prized for its high-quality thin-film formation in the absence of high temperature or high vacuum, has become an industry standard for the large-area deposition of a wide array of oxide materials. Recently, it has shown promise in the formation of nanocrystalline sulfide films. Here, we demonstrate the viability of ALD lead sulfide for photodetection. Leveraging the conformal capabilities of ALD, we enhance the absorption without compromising the extraction efficiency in the absorbing layer by utilizing a ZnO nanowire electrode. The nanowires are first coated with a thin shunt-preventing TiO{sub 2} layer, followed by an infrared-active ALD PbS layer for photosensing. The ALD PbS photodetector exhibits a peak responsivity of 10{sup −2} A W{sup −1} and a shot-derived specific detectivity of 3 × 10{sup 9} Jones at 1530 nm wavelength.

  3. Reduction of short wavelength reflectance of multi-wall carbon nanotubes through ultraviolet laser irradiation

    Science.gov (United States)

    Stephens, Michelle S.; Simonds, Brian J.; Yung, Christopher S.; Conklin, Davis; Livigni, David J.; Oliva, Alberto Remesal; Lehman, John H.

    2018-05-01

    Multi-wall carbon nanotube coatings are used as broadband, low-reflectance absorbers for bolometric applications and for stray light control. They are also used as high emittance blackbody radiators. Irradiation of single wall carbon nanotubes with ultraviolet (UV) laser light has been shown to remove amorphous carbon debris, but there have been few investigations of the interaction of UV light with the more complex physics of multi-wall carbon nanotubes. We present measurements of reflectance and surface morphology before and after exposure of multi-wall carbon nanotube coatings to 248 nm UV laser light. We show that UV exposure reduces the reflectivity at wavelengths below 600 nm and present modeling of the thermal cycling the UV exposure causes at the surface of the carbon nanotubes. This effect can be used to flatten the spectral shape of the reflectivity curve of carbon nanotube absorber coatings used for broadband applications. Finally, we find that the effect of UV exposure depends on the nanotube growth process.

  4. Atomic layer deposition of absorbing thin films on nanostructured electrodes for short-wavelength infrared photosensing

    International Nuclear Information System (INIS)

    Xu, Jixian; Sutherland, Brandon R.; Hoogland, Sjoerd; Fan, Fengjia; Sargent, Edward H.; Kinge, Sachin

    2015-01-01

    Atomic layer deposition (ALD), prized for its high-quality thin-film formation in the absence of high temperature or high vacuum, has become an industry standard for the large-area deposition of a wide array of oxide materials. Recently, it has shown promise in the formation of nanocrystalline sulfide films. Here, we demonstrate the viability of ALD lead sulfide for photodetection. Leveraging the conformal capabilities of ALD, we enhance the absorption without compromising the extraction efficiency in the absorbing layer by utilizing a ZnO nanowire electrode. The nanowires are first coated with a thin shunt-preventing TiO 2 layer, followed by an infrared-active ALD PbS layer for photosensing. The ALD PbS photodetector exhibits a peak responsivity of 10 −2  A W −1 and a shot-derived specific detectivity of 3 × 10 9  Jones at 1530 nm wavelength

  5. Energy and Emission Characteristics of a Short-Arc Xenon Flash Lamp Under "Saturated" Optical Brightness Conditions

    Science.gov (United States)

    Kamrukov, A. S.; Kireev, S. G.; Kozlov, N. P.; Shashkovskii, S. G.

    2017-09-01

    We present the results of a study of the electrical, energy, and spectral brightness characteristics of an experimental three-electrode high-pressure xenon flash lamp under conditions ensuring close to maximum possible spectral brightness for the xenon emission. We show that under saturated optical brightness conditions (brightness temperature in the visible region of the spectrum 30,000 K), emission of a pulsed discharge in xenon is quite different from the emission from an ideal blackbody: the maximum brightness temperatures are 24,000 K in the short-wavelength UV region and 19,000 K in the near IR range. The relative fraction of UV radiation in the emission spectrum of the lamp is >50%, which lets us consider such lamps as promising broadband sources of radiation with high spectral brightness for many important practical applications.

  6. Novel phenomena in clusters irradiated by short-wavelength free-electron lasers

    International Nuclear Information System (INIS)

    Fukuzawa, Hironobu; Ueda, Kiyoshi

    2017-01-01

    By electron spectroscopy, we investigated various phenomena that are caused by the irradiation of extreme ultraviolet (EUV) and X-ray free-electron laser (FEL) pulses on rare-gas clusters. The results for the Ne clusters, which were irradiated by EUVFEL pulses at a photon energy of 20.3 eV below the ionization threshold, illustrate that novel interatomic processes yield low-energy electrons. The results for the Xe clusters, irradiated by EUVFEL pulses at a photon energy of 24.3 eV above the threshold, illustrate that nanoplasma is formed as a result of trapping the photoelectrons and consequently emits low-energy thermal electrons. The results for the Ar clusters irradiated by 5 keV XFEL pulses illustrate that nanoplasma is formed by trapping low-energy Auger electrons and secondary electrons in the tens of fs range, and continuous thermal emission from the plasma occurs in the ps range. (author)

  7. Design and analysis of InN - In0.25Ga0.75N single quantum well laser for short distance communication wavelength

    Science.gov (United States)

    Polash, Md. Mobarak Hossain; Alam, M. Shah; Biswas, Saumya

    2018-03-01

    A single quantum well semiconductor laser based on wurtzite-nitride is designed and analyzed for short distance communication wavelength (at around 1300 nm). The laser structure has 12 Å well layer of InN, 15 Å barrier layer of In0.25Ga0.75N, and 54 Å separate confinement heterostructure layer of GaN. To calculate the electronic characteristics of the structure, a self-consistent method is used where Hamiltonian with effective mass approximation is solved for conduction band while six-bands Hamiltonian matrix with k · p formalism including the polarization effect, valence-band mixing effect, and strain effect is solved for valence band. The interband optical transition elements, optical gain, differential gain, radiative current density, spontaneous emission rate, and threshold characteristics have been calculated. The wave function overlap integral is found to be 45.93% for TE-polarized structure. Also, the spontaneous emission rate is found to be 6.57 × 1027 s - 1 cm - 3 eV - 1 at 1288.21 nm with the carrier density of 5 × 1019 cm - 3. Furthermore, the radiative current density and the radiative recombination rate are found to be 121.92 A cm - 2 and 6.35 × 1027 s - 1 cm - 3, respectively, while the TE-polarized optical gain of the structure is 3872.1 cm - 1 at 1301.7 nm.

  8. Short wavelength automated perimetry can detect visual field changes in diabetic patients without retinopathy

    Directory of Open Access Journals (Sweden)

    Othman Ali Zico

    2014-01-01

    Full Text Available Purpose: The purpose of the following study is to compare short wave automated perimetry (SWAP versus standard automated perimetry (SAP for early detection of diabetic retinopathy (DR. Materials and Methods: A total of 40 diabetic patients, divided into group I without DR (20 patients = 40 eyes and group II with mild non-proliferative DR (20 patients = 40 eyes were included. They were tested with central 24-2 threshold test with both shortwave and SAP to compare sensitivity values and local visual field indices in both of them. A total of 20 healthy age and gender matched subjects were assessed as a control group. Results: Control group showed no differences between SWAP and SAP regarding mean deviation (MD, corrected pattern standard deviation (CPSD or short fluctuations (SF. In group I, MD showed significant more deflection in SWAP (−4.44 ± 2.02 dB compared to SAP (−0.96 ± 1.81 dB (P = 0.000002. However, CPSD and SF were not different between SWAP and SAP. In group II, MD and SF showed significantly different values in SWAP (−5.75 ± 3.11 dB and 2.0 ± 0.95 compared to SAP (−3.91 ± 2.87 dB and 2.86 ± 1.23 (P = 0.01 and 0.006 respectively. There are no differences regarding CPSD between SWAP and SAP. The SWAP technique was significantly more sensitive than SAP in patients without retinopathy (p, but no difference exists between the two techniques in patients with non-proliferative DR. Conclusion: The SWAP technique has a higher yield and efficacy to pick up abnormal findings in diabetic patients without overt retinopathy rather than patients with clinical retinopathy.

  9. MULTI-WAVELENGTH RADIO CONTINUUM EMISSION STUDIES OF DUST-FREE RED GIANTS

    Energy Technology Data Exchange (ETDEWEB)

    O' Gorman, Eamon; Harper, Graham M. [School of Physics, Trinity College Dublin, Dublin 2 (Ireland); Brown, Alexander [Center for Astrophysics and Space Astronomy, University of Colorado, 389 UCB, Boulder, CO 80309 (United States); Drake, Stephen [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Richards, Anita M. S. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

    2013-10-01

    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (α Boo: K2 III) and Aldebaran (α Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for α Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of α Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For α Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of α Boo. Finally, we develop a simple analytical wind model for α Boo based on our new long-wavelength flux measurements.

  10. MULTI-WAVELENGTH RADIO CONTINUUM EMISSION STUDIES OF DUST-FREE RED GIANTS

    International Nuclear Information System (INIS)

    O'Gorman, Eamon; Harper, Graham M.; Brown, Alexander; Drake, Stephen; Richards, Anita M. S.

    2013-01-01

    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (α Boo: K2 III) and Aldebaran (α Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for α Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of α Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For α Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of α Boo. Finally, we develop a simple analytical wind model for α Boo based on our new long-wavelength flux measurements

  11. Multi-wavelength Radio Continuum Emission Studies of Dust-free Red Giants

    Science.gov (United States)

    O'Gorman, Eamon; Harper, Graham M.; Brown, Alexander; Dranke, Stephen; Richards, Anita M. S.

    2013-01-01

    Multi-wavelength centimeter continuum observations of non-dusty, non-pulsating K spectral-type red giants directly sample their chromospheres and wind acceleration zones. Such stars are feeble emitters at these wavelengths, however, and previous observations have provided only a small number of modest signal-to-noise measurements slowly accumulated over three decades. We present multi-wavelength Karl G. Jansky Very Large Array thermal continuum observations of the wind acceleration zones of two dust-free red giants, Arcturus (alpha Boo: K2 III) and Aldebaran (alpha Tau: K5 III). Importantly, most of our observations of each star were carried out over just a few days, so that we obtained a snapshot of the different stellar atmospheric layers sampled at different wavelengths, independent of any long-term variability. We report the first detections at several wavelengths for each star including a detection at 10 cm (3.0 GHz: S band) for both stars and a 20 cm (1.5 GHz: L band) detection for alpha Boo. This is the first time single (non-binary) luminosity class III red giants have been detected at these continuum wavelengths. Our long-wavelength data sample the outer layers of alpha Boo's atmosphere where its wind velocity is approaching (or possibly has reached) its terminal value and the ionization balance is becoming frozen-in. For alpha Tau, however, our long-wavelength data are still sampling its inner atmosphere, where the wind is still accelerating probably due to its lower mass-loss rate. We compare our data with published semi-empirical models based on ultraviolet data, and the marked deviations highlight the need for new atmospheric models to be developed. Spectral indices are used to discuss the possible properties of the stellar atmospheres, and we find evidence for a rapidly cooling wind in the case of alpha Boo. Finally, we develop a simple analytical wind model for alpha Boo based on our new long-wavelength flux measurements.

  12. Free electron lasers and short wavelengths: state of the art and prospects

    International Nuclear Information System (INIS)

    Couprie, M.E.

    2003-01-01

    Free electron lasers generate coherent and adjustable radiation that is based on the interaction of a light wave with a relativistic electron beam circulating in a periodic and permanent magnetic field produced by an ondulator. The light wave comes from either - synchrotron radiation emitted by the electron packet at each round in the case of SASE (self amplified spontaneous emission) operating more, or - synchrotron radiation stored in an optic cavity in the case of oscillator operating mode, or - an external laser wave in the case of harmonic generation operating mode. Under particular conditions the light wave is amplified to the detriment of the kinetic energy of the electrons which leads to the laser effect. 5 free electron lasers are operating in the world: Super-Aco in France, Elettra in Italy, NIJI-4 and Uvsor in Japan, and Duke in Usa. The state of the art of free electron lasers in the UV, VUV range is presented and the different configurations associated to storage rings, linac and ERL (energy recovery linacs) are described. (A.C.)

  13. Expression and Evolution of Short Wavelength Sensitive Opsins in Colugos: A Nocturnal Lineage That Informs Debate on Primate Origins.

    Science.gov (United States)

    Moritz, Gillian L; Lim, Norman T-L; Neitz, Maureen; Peichl, Leo; Dominy, Nathaniel J

    2013-01-01

    A nocturnal activity pattern is central to almost all hypotheses on the adaptive origins of primates. This enduring view has been challenged in recent years on the basis of variation in the opsin genes of nocturnal primates. A correspondence between the opsin genes and activity patterns of species in Euarchonta-the superordinal group that includes the orders Primates, Dermoptera (colugos), and Scandentia (treeshrews)-could prove instructive, yet the basic biology of the dermopteran visual system is practically unknown. Here we show that the eye of the Sunda colugo ( Galeopterus variegatus ) lacks a tapetum lucidum and has an avascular retina, and we report on the expression and spectral sensitivity of cone photopigments. We found that Sunda colugos have intact short wavelength sensitive (S-) and long wavelength sensitive (L-) opsin genes, and that both opsins are expressed in cone photoreceptors of the retina. The inferred peak spectral sensitivities are 451 and 562 nm, respectively. In line with adaptation to nocturnal vision, cone densities are low. Surprisingly, a majority of S-cones coexpress some L-opsin. We also show that the ratio of rates of nonsynonymous to synonymous substitutions of exon 1 of the S-opsin gene is indicative of purifying selection. Taken together, our results suggest that natural selection has favored a functional S-opsin in a nocturnal lineage for at least 45 million years. Accordingly, a nocturnal activity pattern remains the most likely ancestral character state of euprimates.

  14. The pre-launch Planck Sky Model: a model of sky emission at submillimetre to centimetre wavelengths

    CERN Document Server

    Delabrouille, J.; Melin, J.-B.; Miville-Deschenes, M.-A.; Gonzalez-Nuevo, J.; Jeune, M.Le; Castex, G.; de Zotti, G.; Basak, S.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.; Bernard, J.-P.; Bouchet, F.R.; Clements, D.L.; da Silva, A.; Dickinson, C.; Dodu, F.; Dolag, K.; Elsner, F.; Fauvet, L.; Fay, G.; Giardino, G.; Leach, S.; Lesgourgues, J.; Liguori, M.; Macias-Perez, J.F.; Massardi, M.; Matarrese, S.; Mazzotta, P.; Montier, L.; Mottet, S.; Paladini, R.; Partridge, B.; Piffaretti, R.; Prezeau, G.; Prunet, S.; Ricciardi, S.; Roman, M.; Schaefer, B.; Toffolatti, L.

    2012-01-01

    We present the Planck Sky Model (PSM), a parametric model for the generation of all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H-II regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are: spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modeling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared back...

  15. Spectroscopic studies of xenon EUV emission in the 40-80 nm wavelength range using an absolutely calibrated monochromator

    Energy Technology Data Exchange (ETDEWEB)

    Merabet, H [Mathematic and Sciences Unit, Dhofar University, Salalah 211, Sultanate of (Oman); Bista, R [Department of Physics, University of Nevada Reno, Reno, NV 89557 (United States); Bruch, R [Department of Physics, University of Nevada Reno, Reno, NV 89557 (United States); Fuelling, S [Department of Physics, University of Nevada Reno, Reno, NV 89557 (United States)

    2007-03-01

    We have measured and identified numerous Extreme UltraViolet (EUV) radiative line structures arising from xenon (Xe) ions in charge state q = 1 to 10 in the wavelength range 40-80 nm. To obtain reasonable intensities of different charged Xe ions, we have used a compact microwave plasma source which was designed and developed at the Lawrence Berkeley National Laboratory (LBNL). The EUV emission of the ECR plasma has been measured by a 1.5 m grazing incidence monochromator that was absolutely calibrated in the 10-80 nm wavelength range using well known and calibrated EUV light at the Advanced Light Source (ALS), LBNL. This calibration has enabled us to determine absolute intensities of previously measured EUV radiative lines in the wavelengths regions investigated for different ionization stages of Xe. In addition, emission spectra of xenon ions for corresponding measured lines have been calculated. The calculations have been carried out within the relativistic Hartree-Fock (HF) approximation. Results of calculations are found to be in good agreement with current and available experimental and theoretical data.

  16. Modification of erbium photoluminescence excitation spectra for the emission wavelength 1.54 μm in mesoscopic structures

    International Nuclear Information System (INIS)

    Gaponenko, N.V.; Unuchak, D.M.; Mudryi, A.V.; Malyarevich, G.K.; Gusev, O.B.; Stepikhova, M.V.; Krasilnikova, L.V.; Stupak, A.P.; Kleshcheva, S.M.; Samoilovich, M.I.; Tsvetkov, M.Yu.

    2006-01-01

    Photoluminescence excitation (PLE) spectra for the emission wavelength 1.54 μm were studied for erbium-doped xerogels embedded in artificial opals and porous anodic alumina films. Opals were chosen with photonic stop-band in green spectral range, where excitation of 1.54 μm occurs most efficiently. In comparison to the structure erbium-doped titania xerogel/porous anodic alumina/silicon the photoluminescence excitation spectra for 1.54 μm emission wavelength significantly changes for the same xerogels embedded in artificial opals. Enhancement of erbium-related 1.54 μm emission was observed from the structure Fe 2 O 3 xerogel/porous anodic alumina fabricated on silicon, having some incompletely anodized aluminium, under excitation with either the lasing source at 532 nm or xenon lamp. Evident difference in PLE spectra for erbium doped TiO 2 and Fe 2 O 3 xerogels in porous anodic alumina is observed

  17. Planck intermediate results. XIV. Dust emission at millimetre wavelengths in the Galactic plane

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Alves, Marie-Helene

    2014-01-01

    We use Planck HFI data combined with ancillary radio data to study the emissivity index of the interstellar dust emission in the frequency range 100-353 GHz, or 3-0.8 mm, in the Galactic plane. We analyse the region l = 20 degrees-44 degrees and vertical bar b vertical bar...

  18. Effects of laser wavelengths and pulse energy ratio on the emission enhancement in dual pulse LIBS

    International Nuclear Information System (INIS)

    Ahmed, Rizwan; Iqbal, Javed; Baig, M Aslam

    2015-01-01

    We present new studies on the effects of laser wavelengths, pulse energy ratio and interpulse delay between two laser pulses in the collinear dual pulse configuration of laser-induced breakdown spectroscopy (LIBS) on an iron sample in air using the fundamental (1064 nm) and the second harmonics (532 nm) of Nd:YAG lasers. In the dual pulse LIBS, an optimum value of interpulse delay with an appropriate combination of laser wavelengths, and laser pulse energy ratio, yields a 30 times signal intensity enhancement in the neutral iron lines as compared with single pulse LIBS. A comparison in the spatial variations of electron temperature along the axis of the plume expansion in single and double pulse LIBS has also been studied. (letter)

  19. Evidence for nonuniversal behavior of paraconductivity caused by predominant short-wavelength Gaussian fluctuations in YBa2Cu3O6.9

    International Nuclear Information System (INIS)

    Gauzzi, A.; Pavuna, D.

    1995-01-01

    We report on in-plane paraconductivity measurements in thin YBa 2 Cu 3 O 6.9 films. Our analysis of the data shows that the temperature dependence of paraconductivity is affected by lattice disorder and deviates at all temperatures from the universal power laws predicted by both scaling and mean-field theories. This gives evidence for the absence of critical fluctuations and for the failure of the Aslamazov-Larkin universal relation between critical exponent and dimensionality of the spectrum of Gaussian fluctuations. We account quantitatively for the data within the experimental error by introducing a short-wavelength cutoff into this spectrum. This implies that three-dimensional short-wavelength Gaussian fluctuations dominate in YBa 2 Cu 3 O 6.9 and suggests a rapid attenuation of these fluctuations with decreasing wavelength in short-coherence-length systems as compared to the case of the conventional Ginzburg-Landau theory

  20. Near-Infrared Phosphorus-Substituted Rhodamine with Emission Wavelength above 700 nm for Bioimaging.

    Science.gov (United States)

    Chai, Xiaoyun; Cui, Xiaoyan; Wang, Baogang; Yang, Fan; Cai, Yi; Wu, Qiuye; Wang, Ting

    2015-11-16

    Phosphorus has been successfully fused into a classic rhodamine framework, in which it replaces the bridging oxygen atom to give a series of phosphorus-substituted rhodamines (PRs). Because of the electron-accepting properties of the phosphorus moiety, which is due to effective σ*-π* interactions and strengthened by the inductivity of phosphine oxide, PR exhibits extraordinary long-wavelength fluorescence emission, elongating to the region above 700 nm, with bathochromic shifts of 140 and 40 nm relative to rhodamine and silicon-substituted rhodamine, respectively. Other advantageous properties of the rhodamine family, including high molar extinction coefficient, considerable quantum efficiency, high water solubility, pH-independent emission, great tolerance to photobleaching, and low cytotoxicity, stay intact in PR. Given these excellent properties, PR is desirable for NIR-fluorescence imaging in vivo. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Observations of the polarized emission of Taurus A, Cas A and Cygnus A at 9-mm wavelength

    International Nuclear Information System (INIS)

    Flett, A.M.; Henderson, C.

    1979-01-01

    Measurements of the total intensity and degree of linear polarization of the supernova remnants Taurus A and Cas A and of the radiogalaxy Cygnus A have been made at lambda 9 mm using the 25-m radiotelescope at Chilbolton. A new experimental technique involving Faraday rotation of the incoming polarized radiation was employed. Taurus A shows the expected strong and uniform polarization over the central area investigated, and Cas A the ring-like distribution observed at other wavelengths. The beamwidth of 1.5 arcmin resolves the two major components of Cygnus A and it is found that the polarization in the E component has a position angle of 53 +- 3 0 and P = 7.5 +- 1.2 per cent, and the W component a position angle of 133 +- 3 0 and P = 9.6 +-1.1 per cent. When these results are combined with earlier data at longer wavelengths, the large rotation measure of the E component and the fall of the degree of polarization of the W component at short wavelength are further established. (author)

  2. Relationship between short-wavelength automatic perimetry and Heidelberg retina tomograph parameters in eyes with ocular hypertension

    Directory of Open Access Journals (Sweden)

    Christos Pitsas

    2015-10-01

    Full Text Available AIM:To compare and correlate optic nerve head parameters obtained byHeidelberg retina tomograph (HRT with short-wavelength automatic perimetry (SWAP indices in eyes with ocular hypertension (OHT.METHODS: One hundred and forty-six patients with OHT included in the present study. All subjects had reliable SWAP and HRT measurements performed within a 2wk period. The eyes were classified as normal/abnormal according to visual field criteria and Moorfields regression analysis (MRA. Correlations between visual field indices and HRT parameters were analyzed using Pearson correlation coefficient (r.RESULTS:Twenty-nine eyes (19.9% had SWAP defects. Twenty-nine eyes (19.9% were classified as abnormal according to global MRA. Six eyes (4.1% had abnormal global MRA and SWAP defects. The k statistic is 0.116 (P=0.12 indicating a very poor agreement between the methods. No statistical significant correlation between HRT and SWAP parameters was detected.CONCLUSION:SWAP defects may coexist with abnormalities of optic disc detected by HRT in eyes with OHT. In most eyes, however, the two methods detect different glaucoma properties.

  3. Multiple pathways carry signals from short-wavelength-sensitive ('blue') cones to the middle temporal area of the macaque.

    Science.gov (United States)

    Jayakumar, Jaikishan; Roy, Sujata; Dreher, Bogdan; Martin, Paul R; Vidyasagar, Trichur R

    2013-01-01

    We recorded spike activity of single neurones in the middle temporal visual cortical area (MT or V5) of anaesthetised macaque monkeys. We used flashing, stationary spatially circumscribed, cone-isolating and luminance-modulated stimuli of uniform fields to assess the effects of signals originating from the long-, medium- or short- (S) wavelength-sensitive cone classes. Nearly half (41/86) of the tested MT neurones responded reliably to S-cone-isolating stimuli. Response amplitude in the majority of the neurones tested further (19/28) was significantly reduced, though not always completely abolished, during reversible inactivation of visuotopically corresponding regions of the ipsilateral primary visual cortex (striate cortex, area V1). Thus, the present data indicate that signals originating in S-cones reach area MT, either via V1 or via a pathway that does not go through area V1. We did not find a significant difference between the mean latencies of spike responses of MT neurones to signals that bypass V1 and those that do not; the considerable overlap we observed precludes the use of spike-response latency as a criterion to define the routes through which the signals reach MT.

  4. Characterization of Low Noise TES Detectors Fabricated by D-RIE Process for SAFARI Short-Wavelength Band

    Science.gov (United States)

    Khosropanah, P.; Suzuki, T.; Hijmering, R. A.; Ridder, M. L.; Lindeman, M. A.; Gao, J.-R.; Hoevers, H.

    2014-08-01

    SRON is developing TES detectors based on a superconducting Ti/Au bilayer on a suspended SiN membrane for the short-wavelength band of the SAFARI instrument on SPICA mission. We have recently replaced the wet KOH etching of the Si substrate by deep reactive ion etching. The new process enables us to fabricate the detectors on the substrate and release the membrane at the very last step. Therefore the production of SAFARI large arrays (4343) on thin SiN membrane (250 nm) is feasible. It also makes it possible to realize narrow supporting SiN legs of 1 m, which are needed to meet SAFARI NEP requirements. Here we report the current-voltage characteristics, noise performance and impedance measurement of these devices. The measured results are then compared with the distributed leg model that takes into account the thermal fluctuation noise due to the SiN legs. We measured a dark NEP of 0.7 aW/, which is 1.6 times higher than the theoretically expected phonon noise.

  5. Effects of low or high doses of short wavelength ultraviolet light (UVB) on Langerhans cells and skin allograft survival

    International Nuclear Information System (INIS)

    Odling, K.A.; Halliday, G.M.; Muller, H.K.

    1987-01-01

    Donor C57BL mouse shaved dorsal trunk or tail skin was exposed to high (200 mJ/cm 2 ) or low (40 mJ/cm 2 ) doses of short wavelength ultraviolet light (UVB) before grafting on to the thorax of BALB/c mouse recipients of the same sex. Skin grafted 1-14 days following a single high dose of UVB irradiation was ultrastructurally depleted of LC and survived significantly longer than unirradiated skin before being rejected. After a 21-day interval between exposure and grafting when LC were again present in the epidermis there was no significant difference between treated and control graft survival. Exposure to low dose UVB irradiation only significantly increased graft survival for skin transplanted 1-3 days after irradiation; skin grafted 4 days following irradiation survived for a similar period to unirradiated control skin grafts. Electronmicroscopy showed that the low UVB dose did not deplete LC from the epidermis. We conclude that after low dose UVB treatment the class II MHC antigens on the LC Plasma membrane were lost temporarily, thus prolonging graft survival, but when the plasma membrane antigens were re-expressed graft survival returned to normal. In contrast, high-dose UVB irradiation prolonged graft survival by depleting LC from the epidermis, with graft survival only returning to control values as LC repopulated the epidermis

  6. Vehicle emissions of short-lived and long-lived climate forcers: trends and tradeoffs.

    Science.gov (United States)

    Edwards, Morgan R; Klemun, Magdalena M; Kim, Hyung Chul; Wallington, Timothy J; Winkler, Sandra L; Tamor, Michael A; Trancik, Jessika E

    2017-08-24

    Evaluating technology options to mitigate the climate impacts of road transportation can be challenging, particularly when they involve a tradeoff between long-lived emissions (e.g., carbon dioxide) and short-lived emissions (e.g., methane or black carbon). Here we present trends in short- and long-lived emissions for light- and heavy-duty transport globally and in the U.S., EU, and China over the period 2000-2030, and we discuss past and future changes to vehicle technologies to reduce these emissions. We model the tradeoffs between short- and long-lived emission reductions across a range of technology options, life cycle emission intensities, and equivalency metrics. While short-lived vehicle emissions have decreased globally over the past two decades, significant reductions in CO 2 will be required by mid-century to meet climate change mitigation targets. This is true regardless of the time horizon used to compare long- and short-lived emissions. The short-lived emission intensities of some low-CO 2 technologies are higher than others, and thus their suitability for meeting climate targets depends sensitively on the evaluation time horizon. Other technologies offer low intensities of both short-lived emissions and CO 2 .

  7. Shifting wavelengths of ultraweak photon emissions from dying melanoma cells: their chemical enhancement and blocking are predicted by Cosic's theory of resonant recognition model for macromolecules.

    Science.gov (United States)

    Dotta, Blake T; Murugan, Nirosha J; Karbowski, Lukasz M; Lafrenie, Robert M; Persinger, Michael A

    2014-02-01

    During the first 24 h after removal from incubation, melanoma cells in culture displayed reliable increases in emissions of photons of specific wavelengths during discrete portions of this interval. Applications of specific filters revealed marked and protracted increases in infrared (950 nm) photons about 7 h after removal followed 3 h later by marked and protracted increases in near ultraviolet (370 nm) photon emissions. Specific wavelengths within the visible (400 to 800 nm) peaked 12 to 24 h later. Specific activators or inhibitors for specific wavelengths based upon Cosic's resonant recognition model elicited either enhancement or diminishment of photons at the specific wavelength as predicted. Inhibitors or activators predicted for other wavelengths, even within 10 nm, were less or not effective. There is now evidence for quantitative coupling between the wavelength of photon emissions and intrinsic cellular chemistry. The results are consistent with initial activation of signaling molecules associated with infrared followed about 3 h later by growth and protein-structural factors associated with ultraviolet. The greater-than-expected photon counts compared with raw measures through the various filters, which also function as reflective material to other photons, suggest that photons of different wavelengths might be self-stimulatory and could play a significant role in cell-to-cell communication.

  8. Role of short-wavelength filtering lenses in delaying myopia progression and amelioration of asthenopia in juveniles

    Directory of Open Access Journals (Sweden)

    Hai-Lan Zhao

    2017-08-01

    Full Text Available AIM: To evaluate the positive effects of blue-violet light filtering lenses in delaying myopia and relieving asthenopia in juveniles. METHODS: Sixty ametropia juveniles (aged range, 11-15y were randomized into two groups: the test group (30 children, 60 eyes, wearing blue-violet light filtering lenses; and the control group (30 children, 60 eyes, wearing ordinary aspherical lenses. Baseline refractive power of the affected eyes and axial length of the two groups was recorded. After 1-year, the patients underwent contrast sensitivity (glare and non-glare under bright and dark conditions, accommodation-related testing, asthenopia questionnaire assessment, and adverse reaction questionnaire assessment. RESULTS: After 1y of wearing the filtering lenses, changes in refractive power and axial length were not significantly different between the two groups (P>0.05. Under bright conditions, the contrast sensitivities at low and medium-frequency grating (vision angles of 6.3°, 4.0°, and 2.5° with glare in the test group were significantly higher than in the control group (P0.05. In the test group, the amplitude of accommodation, accommodative lag, and accommodative sensitivity of patients wearing glasses for 6 and 12mo were significantly elevated (P0.05, and the asthenopia grating was not significantly decreased (P>0.05. In addition, after wearing glasses for 6 to 12mo, the asthenopia grating of patients in the test group decreased significantly compared with the control group (P0.05. CONCLUSION: A 1-year follow-up reveal that compare with ordinary glasses, short-wavelength filtering lenses (blue/violet-light filters increase the low- and medium-frequency contrast sensitivity under bright conditions and improved accommodation. They effectively relieved asthenopia without severe adverse reactions, suggesting potential for clinical application. However, no significant advantages in terms of refractive power or axial length progression were found compared

  9. Short wavelength lateral variability of lithospheric mantle beneath the Middle Atlas (Morocco) as recorded by mantle xenoliths

    Science.gov (United States)

    El Messbahi, Hicham; Bodinier, Jean-Louis; Vauchez, Alain; Dautria, Jean-Marie; Ouali, Houssa; Garrido, Carlos J.

    2015-05-01

    mountains results from the combination of different mechanisms and occurred in a piecewise fashion at a short wavelength scale.

  10. Comparison of XH2O Retrieved from GOSAT Short-Wavelength Infrared Spectra with Observations from the TCCON Network

    Directory of Open Access Journals (Sweden)

    Eric Dupuy

    2016-05-01

    Full Text Available Understanding the atmospheric distribution of water (H 2 O is crucial for global warming studies and climate change mitigation. In this context, reliable satellite data are extremely valuable for their global and continuous coverage, once their quality has been assessed. Short-wavelength infrared spectra are acquired by the Thermal And Near-infrared Sensor for carbon Observation-Fourier Transform Spectrometer (TANSO-FTS aboard the Greenhouse gases Observing Satellite (GOSAT. From these, column-averaged dry-air mole fractions of carbon dioxide, methane and water vapor (XH 2 O have been retrieved at the National Institute for Environmental Studies (NIES, Japan and are available as a Level 2 research product. We compare the NIES XH 2 O data, Version 02.21, with retrievals from the ground-based Total Carbon Column Observing Network (TCCON, Version GGG2014. The datasets are in good overall agreement, with GOSAT data showing a slight global low bias of −3.1% ± 24.0%, good consistency over different locations (station bias of −1.53% ± 10.35% and reasonable correlation with TCCON (R = 0.89. We identified two potential sources of discrepancy between the NIES and TCCON retrievals over land. While the TCCON XH 2 O amounts can reach 6000–7000 ppm when the atmospheric water content is high, the correlated NIES values do not exceed 5500 ppm. This could be due to a dry bias of TANSO-FTS in situations of high humidity and aerosol content. We also determined that the GOSAT-TCCON differences directly depend on the altitude difference between the TANSO-FTS footprint and the TCCON site. Further analysis will account for these biases, but the NIES V02.21 XH 2 O product, after public release, can already be useful for water cycle studies.

  11. 1.3 mm WAVELENGTH VLBI OF SAGITTARIUS A*: DETECTION OF TIME-VARIABLE EMISSION ON EVENT HORIZON SCALES

    International Nuclear Information System (INIS)

    Fish, Vincent L.; Doeleman, Sheperd S.; Beaudoin, Christopher; Bolin, David E.; Rogers, Alan E. E.; Blundell, Ray; Gurwell, Mark A.; Moran, James M.; Primiani, Rurik; Bower, Geoffrey C.; Plambeck, Richard; Chamberlin, Richard; Freund, Robert; Friberg, Per; Honma, Mareki; Oyama, Tomoaki; Inoue, Makoto; Krichbaum, Thomas P.; Lamb, James; Marrone, Daniel P.

    2011-01-01

    Sagittarius A*, the ∼4 x 10 6 M sun black hole candidate at the Galactic center, can be studied on Schwarzschild radius scales with (sub)millimeter wavelength very long baseline interferometry (VLBI). We report on 1.3 mm wavelength observations of Sgr A* using a VLBI array consisting of the JCMT on Mauna Kea, the Arizona Radio Observatory's Submillimeter Telescope on Mt. Graham in Arizona, and two telescopes of the CARMA array at Cedar Flat in California. Both Sgr A* and the quasar calibrator 1924-292 were observed over three consecutive nights, and both sources were clearly detected on all baselines. For the first time, we are able to extract 1.3 mm VLBI interferometer phase information on Sgr A* through measurement of closure phase on the triangle of baselines. On the third night of observing, the correlated flux density of Sgr A* on all VLBI baselines increased relative to the first two nights, providing strong evidence for time-variable change on scales of a few Schwarzschild radii. These results suggest that future VLBI observations with greater sensitivity and additional baselines will play a valuable role in determining the structure of emission near the event horizon of Sgr A*.

  12. Major constituent quantitative determination in uranium alloys by coupled plasma atomic emission spectrometry and X ray fluorescence wavelength dispersive spectrometry

    International Nuclear Information System (INIS)

    Oliveira, Luis Claudio de; Silva, Adriana Mascarenhas Martins da; Gomide, Ricardo Goncalves; Silva, Ieda de Souza

    2013-01-01

    A wavelength-dispersive X-ray fluorescence (WD-XRF) spectrometric method for determination of major constituents elements (Zr, Nb, Mo) in Uranium/Zirconium/Niobium and Uranium/Molybdenum alloy samples were developed. The methods use samples taken in the form of chips that were dissolved in hot nitric acid and precipitate particles melted with lithium tetraborate and dissolved in hot nitric acid and finally analyzed as a solution. Studies on the determination by inductively coupled plasma optic emission spectrometry (ICP OES) using matched matrix in calibration curve were developed. The same samples solution were analyzed in both methods. The limits of detection (LOD), linearity of the calibrations curves, recovery study, accuracy and precision of the both techniques were carried out. The results were compared. (author)

  13. Proportion of influence phases anatase and rutile TiO_2 in the photoluminescence 538 nm emission wavelength

    International Nuclear Information System (INIS)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M.; Viana, R.S.; Junior, S.A.

    2016-01-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO_2 molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm"3 and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  14. Long wavelength stimulated emission up to 9.5 μm from HgCdTe quantum well heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, S. V.; Rumyantsev, V. V., E-mail: rumyantsev@ipmras.ru; Dubinov, A. A.; Kudryavtsev, K. E.; Antonov, A. V.; Gavrilenko, V. I. [Institute for Physics of Microstructures of Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod, 603950 Nizhny Novgorod (Russian Federation); Kadykov, A. M. [Institute for Physics of Microstructures of Russian Academy of Sciences, 603950 Nizhny Novgorod (Russian Federation); UMR CNRS 5221, GIS-TERALAB, Université Montpellier II, 34095 Montpellier (France); Mikhailov, N. N. [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation); Novosibirsk State University, 630090 Novosibirsk (Russian Federation); Dvoretskii, S. A. [A.V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, 630090 Novosibirsk (Russian Federation)

    2016-02-29

    Stimulated emission from waveguide HgCdTe structures with several quantum wells inside waveguide core is demonstrated at wavelengths up to 9.5 μm. Photoluminescence line narrowing down to kT energy, as well as superlinear rise in its intensity evidence the onset of the stimulated emission, which takes place under optical pumping with intensity as small as ∼0.1 kW/cm{sup 2} at 18 K and 1 kW/cm{sup 2} at 80 K. One can conclude that HgCdTe structures potential for long-wavelength lasers is not exhausted.

  15. Tuning direct bandgap GeSn/Ge quantum dots' interband and intraband useful emission wavelength: Towards CMOS compatible infrared optical devices

    Science.gov (United States)

    Baira, Mourad; Salem, Bassem; Madhar, Niyaz Ahamad; Ilahi, Bouraoui

    2018-05-01

    In this work, interband and intraband optical transitions from direct bandgap strained GeSn/Ge quantum dots are numerically tuned by evaluating the confined energies for heavy holes and electrons in D- and L-valley. The practically exploitable emission wavelength ranges for efficient use in light emission and sensing should fulfill specific criteria imposing the electrons confined states in D-valley to be sufficiently below those in L-valley. This study shows that GeSn quantum dots offer promising opportunity towards high efficient group IV based infrared optical devices operating in the mid-IR and far-IR wavelength regions.

  16. Excitation wavelength dependent photoluminescence emission behavior, UV induced photoluminescence enhancement and optical gap tuning of Zn0.45Cd0.55S nanoparticles for optoelectronic applications

    Science.gov (United States)

    Osman, M. A.; Abd-Elrahim, A. G.

    2018-03-01

    In the present study, we investigate the excitation wavelength (λex) dependent photoluminescence (PL) behavior in Zn0.45Cd0.55S nanoparticles. The deconvoluted PL emission bands for nanopowders and nanocolloids reveal noticeable spectral blue shift with decreasing λex accompanied by intensity enhancement. This unusual behavior is explained in terms of selective particle size distribution in nanostructures, advancing of fast ionization process at short λex; and solvation process in polar solvent. In addition, we attributed the UV-induced PL intensity enhancement and blue shift of the optical gap to the reduction in particle size by photo-corrosion process associated with the improvement in the quantum size effect; surface modification due to cross-linkage improvement of capping molecules at NPs surface; the creation of new radiative centers and the formation of photo-passivation layers from ZnSO4 and CdSO4, and photo-enhanced oxygen adsorption on Zn0.45Cd0.55S nanoparticles surface.

  17. Experimental studies on the production and suppression mechanism of the hot electrons produced by short wavelength laser

    International Nuclear Information System (INIS)

    Qi Lanying; Jiang Xiaohua; Zhao Xuewei; Li Sanwei; Zhang Wenhai; Li Chaoguang; Zheng Zhijian; Ding Yongkun

    1999-12-01

    The experiments on gold-disk and hohlraum and plastic hydrocarbon (CH) film targets irradiated by laser beams with wavelength 0.35 μm (Xingguang-II) and 0.53 μm (Shenguang-I) are performed. The characteristics of hot electrons are commonly deduced from spectrum of hard X-ray. Associated with the measurement of backward SRS and 3/2ω 0 , the production mechanism of hot electrons for different target type is analyzed in laser plasma with shorter wavelength. A effective way to suppress hot electrons has been found

  18. Backscattering of gyrotron radiation and short-wavelength turbulence during electron cyclotron resonance plasma heating in the L-2M stellarator

    Energy Technology Data Exchange (ETDEWEB)

    Batanov, G. M.; Borzosekov, V. D., E-mail: tinborz@gmail.com; Kovrizhnykh, L. M.; Kolik, L. V.; Konchekov, E. M.; Malakhov, D. V.; Petrov, A. E.; Sarksyan, K. A.; Skvortsova, N. N.; Stepakhin, V. D.; Kharchev, N. K. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2013-06-15

    Backscattering of gyrotron radiation ({theta} = {pi}) by short-wavelength density fluctuations (k{sub Up-Tack} = 30 cm{sup -1}) in the plasma of the L-2M stellarator was studied under conditions of electron cyclotron resonance (ECR) plasma heating at the second harmonic of the electron gyrofrequency (75 GHz). The scattering of the O-wave emerging due to the splitting of the linearly polarized gyrotron radiation into the X- and O-waves was analyzed. The signal obtained after homodyne detection of scattered radiation is a result of interference of the reference signal, the quasi-steady component, and the fast oscillating component. The coefficients of reflection of the quasi-steady component, R{sub =}{sup 2}(Y), and fast oscillating component, R{sub {approx}}{sup 2}(Y), of scattered radiation are estimated. The growth of the R{sub {approx}}{sup 2}(Y) coefficient from 3.7 Multiplication-Sign 10{sup -4} to 5.2 Multiplication-Sign 10{sup -4} with increasing ECR heating power from 190 to 430 kW is found to correlate with the decrease in the energy lifetime from 1.9 to 1.46 ms. The relative density of short-wavelength fluctuations is estimated to be Left-Pointing-Angle-Bracket n{sub {approx}}{sup 2} Right-Pointing-Angle-Bracket / Left-Pointing-Angle-Bracket n{sub e}{sup 2} Right-Pointing-Angle-Bracket = 3 Multiplication-Sign 10{sup -7}. It is shown that the frequencies of short-wavelength fluctuations are in the range 10-150 kHz. The recorded short-wavelength fluctuations can be interpreted as structural turbulence, the energy of which comprises {approx}10% of the total fluctuations energy. Simulations of transport processes show that neoclassical heat fluxes are much smaller than anomalous ones. It is suggested that short-wavelength turbulence plays a decisive role in the anomalous heat transport.

  19. Gravitational Waves versus X and Gamma Ray Emission in a Short Gamma-Ray Burst

    OpenAIRE

    Oliveira, F. G.; Rueda, Jorge A.; Ruffini, Remo

    2012-01-01

    The recent progress in the understanding the physical nature of neutron star equilibrium configurations and the first observational evidence of a genuinely short gamma-ray burst, GRB 090227B, allows to give an estimate of the gravitational waves versus the X and Gamma-ray emission in a short gamma-ray burst.

  20. Thin film beam splitter multiple short pulse generation for enhanced Ni-like Ag x-ray laser emission.

    Science.gov (United States)

    Cojocaru, Gabriel V; Ungureanu, Razvan G; Banici, Romeo A; Ursescu, Daniel; Delmas, Olivier; Pittman, Moana; Guilbaud, Olivier; Kazamias, Sophie; Cassou, Kevin; Demailly, Julien; Neveu, Olivier; Baynard, Elsa; Ros, David

    2014-04-15

    An alternative, novel multiple pulse generation scheme was implemented directly after the optical compressor output of an x-ray pump laser. The new method uses a polarization sensitive thin film beam splitter and a half-wavelength wave plate for tuning the energy ratio in the multiple short pulses. Based on this method, an extensive study was made of the running parameters for a grazing incidence pumped silver x-ray laser (XRL) pumped with a long pulse of 145 mJ in 6 ns at 532 nm and up to 1.45 J in few picoseconds at 810 nm. Fivefold enhancement in the emission of the silver XRL was demonstrated using the new pump method.

  1. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    International Nuclear Information System (INIS)

    Shimomura, K.; Kamiya, I.

    2015-01-01

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers

  2. Strain engineering of quantum dots for long wavelength emission: Photoluminescence from self-assembled InAs quantum dots grown on GaAs(001) at wavelengths over 1.55 μm

    Energy Technology Data Exchange (ETDEWEB)

    Shimomura, K., E-mail: sd12502@toyota-ti.ac.jp; Kamiya, I., E-mail: kamiya@toyota-ti.ac.jp [Toyota Technological Institute 2-12-1 Hisakata, Tempaku, Nagoya 468-8511 (Japan)

    2015-02-23

    Photoluminescence (PL) at wavelengths over 1.55 μm from self-assembled InAs quantum dots (QDs) grown on GaAs(001) is observed at room temperature (RT) and 4 K using a bilayer structure with thin cap. The PL peak has been known to redshift with decreasing cap layer thickness, although accompanying intensity decrease and peak broadening. With our strain-controlled bilayer structure, the PL intensity can be comparable to the ordinary QDs while realizing peak emission wavelength of 1.61 μm at 4 K and 1.73 μm at RT. The key issue lies in the control of strain not only in the QDs but also in the cap layer. By combining with underlying seed QD layer, we realize strain-driven bandgap engineering through control of strain in the QD and cap layers.

  3. Improved performance of P3HT:PCBM solar cells by both anode modification and short-wavelength energy utilization using Tb(aca)3phen

    International Nuclear Information System (INIS)

    Zhuo Zu-Liang; Wang Yong-Sheng; He Da-Wei; Fu Ming

    2014-01-01

    The performance of P3HT:PCBM solar cells was improved by anode modification using spin-coated Tb(aca) 3 phen ultrathin films. The modification of the Tb(aca) 3 phen ultrathin film between the indium tin oxide (ITO) anode and the PE-DOT:PSS layer resulted in a maximum power conversion efficiency (PCE) of 2.99% compared to 2.66% for the reference device, which was due to the increase in the short-circuit current density (J sc ). The PCE improvement could be attributed to the short-wavelength energy utilization and the optimized morphology of the active layers. Tb(aca) 3 phen with its strong down-conversion luminescence properties is suitable for the P3HT:PCBM blend active layer, and the absorption region of the ternary blend films is extended into the near ultraviolet region. Furthermore, the crystallization and the surface morphology of P3HT:PCBM films were improved with the Tb(aca) 3 phen ultrathin film. The ultraviolent—visible absorption spectra, atomic force microscope (AFM), and X-ray diffraction (XRD) of the films were investigated. Both anode modification and short-wavelength energy utilization using Tb(aca) 3 phen in P3HT:PCBM solar cells led to about a 12% PCE increase. (interdisciplinary physics and related areas of science and technology)

  4. Short-wavelength soft-x-ray laser pumped in double-pulse single-beam non-normal incidence

    International Nuclear Information System (INIS)

    Zimmer, D.; Ros, D.; Guilbaud, O.; Habib, J.; Kazamias, S.; Zielbauer, B.; Bagnoud, V.; Ecker, B.; Aurand, B.; Kuehl, T.; Hochhaus, D. C.; Neumayer, P.

    2010-01-01

    We demonstrated a 7.36 nm Ni-like samarium soft-x-ray laser, pumped by 36 J of a neodymium:glass chirped-pulse amplification laser. Double-pulse single-beam non-normal-incidence pumping was applied for efficient soft-x-ray laser generation. In this case, the applied technique included a single-optic focusing geometry for large beam diameters, a single-pass grating compressor, traveling-wave tuning capability, and an optimized high-energy laser double pulse. This scheme has the potential for even shorter-wavelength soft-x-ray laser pumping.

  5. A new experimental apparatus for emissivity measurements of steel and the application of multi-wavelength thermometry to continuous casting billets

    Science.gov (United States)

    Wang, Peng; Hu, Zhenwei; Xie, Zhi; Yan, Ming

    2018-05-01

    An experimental apparatus has been designed for measuring the emissivity of a steel surface in both vacuum and oxidation atmosphere. The sample is heated with the method of electromagnetic induction in order to ensure the temperature uniformity. The radiance emitted from a sample is measured using a fiber-optic Fourier transform infrared spectrometer. Using this unique apparatus, we investigated the spectral (2-6 μm) and directional (0°-86°) emissivity of stainless steel 304 with different degrees of surface oxidation at temperatures ranging from 800 to 1100 °C. The experimental results show that the emissivity increases slightly with increasing temperature, which accords with the Hagen-Rubens relation. The emissivity increases rapidly at the initial stage of oxidation, but gradually reaches to a constant value after 20 min. In addition, the directional emissivity has a maximum value at the measuring angle of about 75°. The maximum uncertainty of emissivity is only 3.0% over all the measuring ranges, indicating that this experimental apparatus has a high reliability. In order to measure the surface temperature of casting billets based on multi-wavelength thermometry, the bivariate emissivity function with the two variables, wavelength and temperature, is determined. Temperature measurement results based on our technique are compared with those from common dual-wavelength radiation thermometry. Our approach reduces the measured temperature fluctuation from ±20.7 °C to ±2.8 °C and reflects the temperature variation with the changes of production parameters in real time.

  6. Losses of functional opsin genes, short-wavelength cone photopigments, and color vision--a significant trend in the evolution of mammalian vision.

    Science.gov (United States)

    Jacobs, Gerald H

    2013-03-01

    All mammalian cone photopigments are derived from the operation of representatives from two opsin gene families (SWS1 and LWS in marsupial and eutherian mammals; SWS2 and LWS in monotremes), a process that produces cone pigments with respective peak sensitivities in the short and middle-to-long wavelengths. With the exception of a number of primate taxa, the modal pattern for mammals is to have two types of cone photopigment, one drawn from each of the gene families. In recent years, it has been discovered that the SWS1 opsin genes of a widely divergent collection of eutherian mammals have accumulated mutational changes that render them nonfunctional. This alteration reduces the retinal complements of these species to a single cone type, thus rendering ordinary color vision impossible. At present, several dozen species from five mammalian orders have been identified as falling into this category, but the total number of mammalian species that have lost short-wavelength cones in this way is certain to be much larger, perhaps reaching as high as 10% of all species. A number of circumstances that might be used to explain this widespread cone loss can be identified. Among these, the single consistent fact is that the species so affected are nocturnal or, if they are not technically nocturnal, they at least feature retinal organizations that are typically associated with that lifestyle. At the same time, however, there are many nocturnal mammals that retain functional short-wavelength cones. Nocturnality thus appears to set the stage for loss of functional SWS1 opsin genes in mammals, but it cannot be the sole circumstance.

  7. Reactions of N2(A3SIGMA/sub u/+) and candidates for short wavelength lasers, March 1, 1984-February 28, 1985

    International Nuclear Information System (INIS)

    Setser, D.W.

    1987-01-01

    There are several potential schemes for efficiently generating high concentrations of the first electronically excited state of nitrogen, N 2 (A 3 Σ/sub u/ + , 6.2 eV) by either chemical or electrical pumping. The goal of this proposal is to study ways of utilizing the energy of the N 2 (A) molecules for developing efficient, short wavelength gas lasers. Such lasers are of potential interest for laser fusion. The authors report both excitation-transfer and dissociative excitation-transfer reactions of N 2 (A) that yield electronically-excited diatomic molecules as products. 25 refs

  8. A UV pre-ionized dual-wavelength short-pulse high-power CO{sub 2} laser facility for laser particle acceleration research

    Energy Technology Data Exchange (ETDEWEB)

    Ebrahim, N A; Mouris, J F; Davis, R W

    1994-12-01

    In this report we describe the Chalk River dual-wavelength, short-pulse, single-mode, high-power CO{sub 2} laser facility for research in laser particle acceleration and CANDU materials modifications. The facility is designed and built around UV-preionized transversely-excited atmospheric-pressure (TEA) Lumonics CO{sub 2} laser discharge modules. Peak focussed power densities of up to 2 x 10{sup 14} W/cm{sup 2} in 500 ps pulses have been obtained. (author). 10 refs., 9 figs.

  9. Wavelength dependence of momentum-space images of low-energy electrons generated by short intense laser pulses at high intensities

    International Nuclear Information System (INIS)

    Maharjan, C M; Alnaser, A S; Litvinyuk, I; Ranitovic, P; Cocke, C L

    2006-01-01

    We have measured momentum-space images of low-energy electrons generated by the interaction of short intense laser pulses with argon atoms at high intensities. We have done this over a wavelength range from 400 to 800 nm. The spectra show considerable structure in both the energy and angular distributions of the electrons. Some, but not all, energy features can be identified as multi-photon resonances. The angular structure shows a regularity which transcends the resonant structure and may be due instead to diffraction. The complexity of the results defies easy model-dependent interpretations and invites full solutions to Schroedinger's equation for these systems

  10. Regional emission metrics for short-lived climate forcers from multiple models

    Directory of Open Access Journals (Sweden)

    B. Aamaas

    2016-06-01

    Full Text Available For short-lived climate forcers (SLCFs, the impact of emissions depends on where and when the emissions take place. Comprehensive new calculations of various emission metrics for SLCFs are presented based on radiative forcing (RF values calculated in four different (chemical-transport or coupled chemistry–climate models. We distinguish between emissions during summer (May–October and winter (November–April for emissions in Europe and East Asia, as well as from the global shipping sector and global emissions. The species included in this study are aerosols and aerosol precursors (BC, OC, SO2, NH3, as well as ozone precursors (NOx, CO, VOCs, which also influence aerosols to a lesser degree. Emission metrics for global climate responses of these emissions, as well as for CH4, have been calculated using global warming potential (GWP and global temperature change potential (GTP, based on dedicated RF simulations by four global models. The emission metrics include indirect cloud effects of aerosols and the semi-direct forcing for BC. In addition to the standard emission metrics for pulse and sustained emissions, we have also calculated a new emission metric designed for an emission profile consisting of a ramping period of 15 years followed by sustained emissions, which is more appropriate for a gradual implementation of mitigation policies.For the aerosols, the emission metric values are larger in magnitude for emissions in Europe than East Asia and for summer than winter. A variation is also observed for the ozone precursors, with largest values for emissions in East Asia and winter for CO and in Europe and summer for VOCs. In general, the variations between the emission metrics derived from different models are larger than the variations between regions and seasons, but the regional and seasonal variations for the best estimate also hold for most of the models individually. Further, the estimated climate impact of an illustrative mitigation

  11. Measurements of the growth rate of the short wavelength Rayleigh-Taylor instability of foam foil packages driven by a soft x-ray pulse

    International Nuclear Information System (INIS)

    Willi, O.; Pasley, J.; Iwase, A.; Nazarov, W.; Rose, S.J.

    2000-01-01

    The Rayleigh-Taylor instability was studied in the short wavelength regime using single mode targets that were driven by hohlraum radiation allowing the Takabe-Morse roll-over due to ablative stabilisation to be investigated. A temporally shaped soft x-ray drive was generated by focusing one of the PHEBUS laser beams into a gold hohlraum with a maximum radiation temperature of about 120 eV. Thin plastic foils with sinusoidal modulations with wavelengths between 12 and 50 μm, and a perturbation amplitude of about 10% of the wavelength, were used. A low density 50 mg/cc tri-acrylate foam 150 μm in length facing the hohlraum was attached to the modulated foam target. The targets were radiographed face-on at an x-ray energy of about 1.3 keV with a spatial resolution of about 5 μm using a Wolter-like x-ray microscope coupled to an x-ray streak camera with a temporal resolution of 50 ps. The acceleration was obtained from side-on radiography. 2-D hydrodynamic code simulations have been carried out to compare the experimental results with the simulations. (authors)

  12. Investigation of concept of efficient short wavelength laser. Interim progress report, 1 April 1977-30 April 1978

    Energy Technology Data Exchange (ETDEWEB)

    Piper, L.G.; Krech, R.H.; Taylor, R.L.

    1978-05-01

    Under this program PSI is investigating the photolytic decomposition of a class of endoergic molecules - azides. Because these compounds contain substantial chemical energy, they offer a potentially more efficient approach for the production of electronically excited fragments. The goal of the present program was to acquire sufficient data and understanding of certain fundamental processes to permit the critical evaluation of this approach for laser development. An apparatus was built to study the wavelength-selected photolysis of gaseous, covalent azides. The photolysis source is a frequency doubled, tuneable dye laser. Detection of fragment species is accomplished by observation of primary fluorescence, or by laser-induced fluorescence (LIF) using a second tuneable dye laser. The design of the apparatus is discussed in detail.

  13. MOVPE prepared InAs/GaAs quantum dots covered by GaAsSb layer with long wavelength emission at 1.8 µm

    Czech Academy of Sciences Publication Activity Database

    Zíková, Markéta; Hospodková, Alice; Pangrác, Jiří; Oswald, Jiří; Krčil, Pavel; Hulicius, Eduard; Komninou, Ph.; Kioseoglou, J.

    2015-01-01

    Roč. 414, Mar (2015), 167-171 ISSN 0022-0248 R&D Projects: GA ČR GA13-15286S; GA MŠk(CZ) LM2011026 Institutional support: RVO:68378271 Keywords : long emission wavelength * photocurrent * InAs quantum dots * MOVPE * GaAsSb layer Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.462, year: 2015

  14. Electron emission from insulator surfaces by ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Acuna, M; Gravielle, M S, E-mail: mario@iafe.uba.a, E-mail: msilvia@iafe.uba.a [Institutes de AstronomIa y Fisica del Espacio, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina)

    2009-11-01

    Photoelectron emission from insulator surfaces induced by ultra-short laser pulses is studied within a time-dependent distorted wave method. The proposed approach combines the Volkov phase, which takes into account the laser interaction, with a simple representation of the unperturbed surface states, given by the Tight-binding method. The model is applied to evaluate the photoelectron emission from a LiF(001) surface, finding effects of interference produced by the crystal lattice.

  15. Estimation of waste water treatment plant methane emissions: methodology and results from a short campaign

    Science.gov (United States)

    Yver-Kwok, C. E.; Müller, D.; Caldow, C.; Lebegue, B.; Mønster, J. G.; Rella, C. W.; Scheutz, C.; Schmidt, M.; Ramonet, M.; Warneke, T.; Broquet, G.; Ciais, P.

    2013-10-01

    This paper describes different methods to estimate methane emissions at different scales. These methods are applied to a waste water treatment plant (WWTP) located in Valence, France. We show that Fourier Transform Infrared (FTIR) measurements as well as Cavity Ring Down Spectroscopy (CRDS) can be used to measure emissions from the process to the regional scale. To estimate the total emissions, we investigate a tracer release method (using C2H2) and the Radon tracer method (using 222Rn). For process-scale emissions, both tracer release and chamber techniques were used. We show that the tracer release method is suitable to quantify facility- and some process-scale emissions, while the Radon tracer method encompasses not only the treatment station but also a large area around. Thus the Radon tracer method is more representative of the regional emissions around the city. Uncertainties for each method are described. Applying the methods to CH4 emissions, we find that the main source of emissions of the plant was not identified with certainty during this short campaign, although the primary source of emissions is likely to be from solid sludge. Overall, the waste water treatment plant represents a small part (3%) of the methane emissions of the city of Valence and its surroundings,which is in agreement with the national inventories.

  16. Gridded emission inventory of short-chain chlorinated paraffins and its validation in China.

    Science.gov (United States)

    Jiang, Wanyanhan; Huang, Tao; Mao, Xiaoxuan; Wang, Li; Zhao, Yuan; Jia, Chenhui; Wang, Yanan; Gao, Hong; Ma, Jianmin

    2017-01-01

    China produces approximately 20%-30% of the total global chlorinated paraffins (CPs). The establishment of a short-chain CP (SCCP) emission inventory is a significant step toward risk assessment and regulation of SCCPs in China and throughout the globe. This study developed a gridded SCCPs emission inventory with a 1/4° longitude by 1/4° latitude resolution from 2008 to 2012 for China, which was based on the total annual CPs emissions for the nation. The total national SCCPs emission during this 5-year period was 5651.5 tons. An additive in metal cutting fluids was a major emission source in China, contributing 2680.2 tons to the total atmospheric emissions of SCCPs from 2008 to 2012, followed by the production of CPs (2281.8 tons), plasticizers (514.3 tons), flame retardants (108.6 tons), and net import (66.6 tons). Most of these emission sources are located along the eastern seaboard of China and southern China. A coupled atmospheric transport model was employed to simulate environmental contamination by SCCPs using the gridded emission inventory of SCCPs from 2008 to 2012 as the model initial conditions. Simulated atmospheric and soil concentrations were compared with field monitoring data to validate the emission inventory. The results showed good consistency between modeled and field sampling data, supporting the reliability and credibility of the gridded SCCPs emission inventory that was developed in the present study. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity.

    Science.gov (United States)

    Kaido, Minako; Toda, Ikuko; Oobayashi, Tomoo; Kawashima, Motoko; Katada, Yusaku; Tsubota, Kazuo

    2016-01-01

    To investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT) dry eye (DE). Twenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23-43 years) and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20-49 years) underwent functional visual acuity (VA) examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio. The baseline mean values (logarithm of the minimum angle of resolution, logMAR) of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P 0.05). The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P 0.05). Protecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

  18. Reducing Short-Wavelength Blue Light in Dry Eye Patients with Unstable Tear Film Improves Performance on Tests of Visual Acuity.

    Directory of Open Access Journals (Sweden)

    Minako Kaido

    Full Text Available To investigate whether suppression of blue light can improve visual function in patients with short tear break up time (BUT dry eye (DE.Twenty-two patients with short BUT DE (10 men, 12 women; mean age, 32.4 ± 6.4 years; age range, 23-43 years and 18 healthy controls (10 men, 8 women; mean age, 30.1 ± 7.4 years; age range, 20-49 years underwent functional visual acuity (VA examinations with and without wearing eyeglasses with 50% blue light blocked lenses. The functional VA parameters were starting VA, functional VA, and visual maintenance ratio.The baseline mean values (logarithm of the minimum angle of resolution, logMAR of functional VA and the visual maintenance ratio were significantly worse in the DE patients than in the controls (P 0.05. The DE patients had significant improvement in mean functional VA and visual maintenance ratio while wearing the glasses (P 0.05.Protecting the eyes from short-wavelength blue light may help to ameliorate visual impairment associated with tear instability in patients with DE. This finding represents a new concept, which is that the blue light exposure might be harmful to visual function in patients with short BUT DE.

  19. Optimum electron temperature and density for short-wavelength plasma-lasing from nickel-like ions

    International Nuclear Information System (INIS)

    Masoudnia, Leili; Bleiner, Davide

    2014-01-01

    Soft X-ray lasing across a Ni-like plasma gain-medium requires optimum electron temperature and density for attaining to the Ni-like ion stage and for population inversion in the 3d 9 4d 1 (J=0)→3d 9 4p 1 (J=1) laser transition. Various scaling laws, function of operating parameters, were compared with respect to their predictions for optimum temperatures and densities. It is shown that the widely adopted local thermodynamic equilibrium (LTE) model underestimates the optimum plasma-lasing conditions. On the other hand, non-LTE models, especially when complemented with dielectronic recombination, provided accurate prediction of the optimum plasma-lasing conditions. It is further shown that, for targets with Z equal or greater than the rare-earth elements (e.g. Sm), the optimum electron density for plasma-lasing is not accessible for pump-pulses at λ=1ω=1μm. This observation explains a fundamental difficulty in saturating the wavelength of plasma-based X-ray lasers below 6.8 nm, unless using 2ω pumping

  20. Emission control strategies for short-chain chloroparaffins in two semi-hypothetical case cities

    DEFF Research Database (Denmark)

    Eriksson, Eva; Revitt, M.; Lützhøft, Hans-Christian Holten

    2012-01-01

    The short-chain chloroparaffins (SCCP), (C10-13 chloroalkanes) are identified in the European Water Framework Directive, as priority hazardous substances. Within the ScorePP project, the aim is to develop emission control strategies that can be employed to reduce emissions from urban areas...... into receiving waters. Six different scenarios for mitigating SCCP emissions in two different semi-hypothetical case cities representing eastern inland and northern coastal conditions have been evaluated. The analysis, associated with scenario uncertainty, indicates that the EU legislation, Best Available...

  1. Short term economic emission power scheduling of hydrothermal energy systems using improved water cycle algorithm

    International Nuclear Information System (INIS)

    Haroon, S.S.; Malik, T.N.

    2017-01-01

    Due to the increasing environmental concerns, the demand of clean and green energy and concern of atmospheric pollution is increasing. Hence, the power utilities are forced to limit their emissions within the prescribed limits. Therefore, the minimization of fuel cost as well as exhaust gas emissions is becoming an important and challenging task in the short-term scheduling of hydro-thermal energy systems. This paper proposes a novel algorithm known as WCA-ER (Water Cycle Algorithm with Evaporation Rate) to inspect the short term EEPSHES (Economic Emission Power Scheduling of Hydrothermal Energy Systems). WCA has its ancestries from the natural hydrologic cycle i.e. the raining process forms streams and these streams start flowing towards the rivers which finally flow towards the sea. The worth of WCA-ER has been tested on the standard economic emission power scheduling of hydrothermal energy test system consisting of four hydropower and three thermal plants. The problem has been investigated for the three case studies (i) ECS (Economic Cost Scheduling), (ii) ES (Economic Emission Scheduling) and (iii) ECES (Economic Cost and Emission Scheduling). The results obtained show that WCA-ER is superior to many other methods in the literature in bringing lower fuel cost and emissions. (author)

  2. Does one hour of bright or short-wavelength filtered tablet screenlight have a meaningful effect on adolescents' pre-bedtime alertness, sleep, and daytime functioning?

    Science.gov (United States)

    Heath, Melanie; Sutherland, Cate; Bartel, Kate; Gradisar, Michael; Williamson, Paul; Lovato, Nicole; Micic, Gorica

    2014-05-01

    Electronic media use is prevalent among adolescent populations, as is the frequency of sleeplessness. One mechanism proposed for technology affecting adolescents' sleep is the alerting effects from bright screens. Two explanations are provided. First, screens emit significant amounts of short-wavelength light (i.e. blue), which produces acute alertness and alters sleep timing. Second, later chronotypes are hypothesised to be hypersensitive to evening light. This study analysed the pre-sleep alertness (GO/NOGO task speed, accuracy; subjective sleepiness), sleep (sleep diary, polysomnography), and morning functioning of 16 healthy adolescents (M = 17.4 ± 1.9 yrs, 56% f) who used a bright tablet screen (80 lux), dim screen (1 lux) and a filtered short-wavelength screen (f.lux; 50 lux) for 1 hr before their usual bedtime in a within-subjects protocol. Chronotype was analysed as a continuous between-subjects factor; however, no significant interactions occurred. Significant effects occurred between bright and dim screens for GO/NOGO speed and accuracy. However, the magnitude of these differences was small (e.g. GO/NOGO speed = 23 ms, accuracy = 13%), suggesting minimal clinical significance. No significant effects were found for sleep onset latency, slow-rolling eye movements, or the number of SWS and REM minutes in the first two sleep cycles. Future independent studies are needed to test short (1 hr) vs longer (>2 hrs) screen usage to provide evidence for safe-to-harmful levels of screenlight exposure before adolescents' usual bedtime.

  3. The vertical and the longitudinal dynamic responses of the vehicle-track system to squat-type short wavelength irregularity

    Science.gov (United States)

    Zhao, Xin; Li, Zili; Dollevoet, Rolf

    2013-12-01

    The squat, a kind of rolling contact fatigue occurring on the rail top, can excite the high-frequency vehicle-track interaction effectively due to its geometric deviations with a typical wavelength of 20-40 mm, leading to the accelerated deterioration of a track. In this work, a validated 3D transient finite element model is employed to calculate in the time domain the vertical and the longitudinal dynamic contact forces between the wheel and the rail caused by squats. The vehicle-track structure and the wheel-rail continua are both considered in order to include all the important eigencharacteristics of the system related to squats. By introducing the rotational and translational movements of the wheel, the transient wheel-rail rolling contact is solved in detail by a 3D frictional contact model integrated. The contact filter effect is considered automatically in the simulations by the finite size of the contact patch. The present work focuses on the influences of the length, width and depth of a light squat on the resulted dynamic contact forces, for which idealised defect models are used. The growth of a squat is also modelled to a certain extent by a series of defects with different dimensions. The results show that the system is mainly excited at two frequencies separately in the vertical and the longitudinal dynamics. Their superposition explains the typical appearance of mature squats. As a squat grows up, the magnitude of the excited vibration at the lower frequency increases faster than the one at the higher frequency.

  4. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    NARCIS (Netherlands)

    Amato, F.; Schaap, M.; Denier van der Gon, H.A.C.; Pandolfi, M.; Alastuey, A.; Keuken, M.; Querol, X.

    2013-01-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well

  5. High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

    Science.gov (United States)

    Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

    2014-09-01

    This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

  6. Short-wavelength infrared imaging using low dark current InGaAs detector arrays and vertical-cavity surface-emitting laser illuminators

    Science.gov (United States)

    Macdougal, Michael; Geske, Jon; Wang, Chad; Follman, David

    2011-06-01

    We describe the factors that go into the component choices for a short wavelength IR (SWIR) imager, which include the SWIR sensor, the lens, and the illuminator. We have shown the factors for reducing dark current, and shown that we can achieve well below 1.5 nA/cm2 for 15 μm devices at 7 °C. In addition, we have mated our InGaAs detector arrays to 640×512 readout integrated integrated circuits to make focal plane arrays (FPAs). The resulting FPAs are capable of imaging photon fluxes with wavelengths between 1 and 1.6 μm at low light levels. The dark current associated with these FPAs is extremely low, exhibiting a mean dark current density of 0.26 nA/cm2 at 0 °C. Noise due to the readout can be reduced from 95 to 57 electrons by using off-chip correlated double sampling. In addition, Aerius has developed laser arrays that provide flat illumination in scenes that are normally light-starved. The illuminators have 40% wall-plug efficiency and provide low-speckle illumination, and provide artifact-free imagery versus conventional laser illuminators.

  7. Transition operators in acoustic-wave diffraction theory. I - General theory. II - Short-wavelength behavior, dominant singularities of Zk0 and Zk0 exp -1

    Science.gov (United States)

    Hahne, G. E.

    1991-01-01

    A formal theory of the scattering of time-harmonic acoustic scalar waves from impenetrable, immobile obstacles is established. The time-independent formal scattering theory of nonrelativistic quantum mechanics, in particular the theory of the complete Green's function and the transition (T) operator, provides the model. The quantum-mechanical approach is modified to allow the treatment of acoustic-wave scattering with imposed boundary conditions of impedance type on the surface (delta-Omega) of an impenetrable obstacle. With k0 as the free-space wavenumber of the signal, a simplified expression is obtained for the k0-dependent T operator for a general case of homogeneous impedance boundary conditions for the acoustic wave on delta-Omega. All the nonelementary operators entering the expression for the T operator are formally simple rational algebraic functions of a certain invertible linear radiation impedance operator which maps any sufficiently well-behaved complex-valued function on delta-Omega into another such function on delta-Omega. In the subsequent study, the short-wavelength and the long-wavelength behavior of the radiation impedance operator and its inverse (the 'radiation admittance' operator) as two-point kernels on a smooth delta-Omega are studied for pairs of points that are close together.

  8. Implications of CO2 Emissions Trading for Short-run Electricity Outcomes in Northwest Europe

    International Nuclear Information System (INIS)

    Chen, Y.; Sijm, J.P.M.; Hobbs, B.F.; Lise, W.

    2008-02-01

    We examine the short-run implications of CO2 trading for power production, prices, emissions, and generator profits in northwest Europe in 2005. Simulation results from a transmission-constrained oligopoly model are compared with theoretical analyses to quantify price increases and windfall profits earned by generators. The analyses indicate that the rates at which CO2 costs are passed through to wholesale prices are affected by market competitiveness, merit order changes, and elasticities of demand and supply. Emissions trading results in large windfall profits, much but not all of which is due to free allocation of allowances. Profits also increase for some generators because their generation mix has low emissions, and so they benefit from electricity price increases. Most emission reductions appear to be due to demand response, not generation redispatch

  9. Implications of CO2 Emissions Trading for Short-run Electricity Outcomes in Northwest Europe

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y. [School of Social Sciences, Humanities, and Arts and School of Engineering, Sierra Nevada Research Institute, University of California, Merced, 5200 N. Lake Rd., Merced, CA 95343 (United States); Sijm, J.P.M. [Policy Studies Unit, Energy Research Centre of the Netherlands ECN, P.O. Box 37154, 1020 Amsterdam (Netherlands); Hobbs, B.F. [Department of Geography and Environmental Engineering, The Johns Hopkins University, 3400 N. Charles St, Ames Hall, Baltimore, MD 21218 (United States); Lise, W. [IBS Research and Consultancy, Aga Hamami Caddesi, Aga Han 17/6, Cihangir, 34433 Beyoglu, Istanbul (Turkey)

    2008-02-15

    We examine the short-run implications of CO2 trading for power production, prices, emissions, and generator profits in northwest Europe in 2005. Simulation results from a transmission-constrained oligopoly model are compared with theoretical analyses to quantify price increases and windfall profits earned by generators. The analyses indicate that the rates at which CO2 costs are passed through to wholesale prices are affected by market competitiveness, merit order changes, and elasticities of demand and supply. Emissions trading results in large windfall profits, much but not all of which is due to free allocation of allowances. Profits also increase for some generators because their generation mix has low emissions, and so they benefit from electricity price increases. Most emission reductions appear to be due to demand response, not generation redispatch.

  10. Multi-directional emission and detection of spin waves propagating in yttrium iron garnet with wavelengths down to about 100 nm

    Science.gov (United States)

    Maendl, Stefan; Grundler, Dirk

    2018-05-01

    We performed broadband spin-wave spectroscopy on 200 nm thick yttrium iron garnet containing arrays of partially embedded magnetic nanodisks. Using integrated coplanar waveguides (CPWs), we studied the excitation and transmission of spin waves depending on the presence of nanomagnet arrays of different lateral extensions. By means of the grating coupler effect, we excited spin waves propagating in multiple lateral directions with wavelengths down to 111 nm. They exhibited group velocities of up to 1 km/s. Detection of such short-wavelength spin waves was possible only in symmetrically designed emitter/detector configurations, not with a bare CPW. We report spin waves propagating between grating couplers under oblique angles exhibiting a wave vector component parallel to the CPW. The effective propagation distance amounted to about 80 μm. Such transmission signals were not addressed before and substantiate the versatility of the grating coupler effect for implementing nanomagnonic circuits.

  11. MIT wavelength tables. Volume 2. Wavelengths by element

    International Nuclear Information System (INIS)

    Phelps, F.M. III.

    1982-01-01

    This volume is the first stage of a project to expand and update the MIT wavelength tables first compiled in the 1930's. For 109,325 atomic emission lines, arranged by element, it presents wavelength in air, wavelength in vacuum, wave number and intensity. All data are stored on computer-readable magnetic tape

  12. Observations of Short Gamma-Ray Bursts: Prompt Emission and Afterglow

    Science.gov (United States)

    Berger, Edo

    2011-09-01

    The study of short gamma-ray bursts has been revolutionized by the discovery of afterglows and host galaxies. In this talk I will review observations of the prompt emission, afterglows, and host galaxies, primarily as they pertain to the nature of the progenitor systems. The bulk of the evidence points to the merger of compact objects (NS-NS or NS-BH) making short GRBs the prime candidate for gravitational wave detections with the next generation detectors. This work is partially supported by funds from NASA (through the Swift and Chandra GO programs) and the NSF through an AAG grant.

  13. Determination of Seed Soundness in Conifers Cryptomeria japonica and Chamaecyparis obtusa Using Narrow-Multiband Spectral Imaging in the Short-Wavelength Infrared Range

    Science.gov (United States)

    Matsuda, Osamu; Hara, Masashi; Tobita, Hiroyuki; Yazaki, Kenichi; Nakagawa, Toshinori; Shimizu, Kuniyoshi; Uemura, Akira; Utsugi, Hajime

    2015-01-01

    Regeneration of planted forests of Cryptomeria japonica (sugi) and Chamaecyparis obtuse (hinoki) is the pressing importance to the forest administration in Japan. Low seed germination rate of these species, however, has hampered low-cost production of their seedlings for reforestation. The primary cause of the low germinability has been attributed to highly frequent formation of anatomically unsound seeds, which are indistinguishable from sound germinable seeds by visible observation and other common criteria such as size and weight. To establish a method for sound seed selection in these species, hyperspectral imaging technique was used to identify a wavelength range where reflectance spectra differ clearly between sound and unsound seeds. In sound seeds of both species, reflectance in a narrow waveband centered at 1,730 nm, corresponding to a lipid absorption band in the short-wavelength infrared (SWIR) range, was greatly depressed relative to that in adjacent wavebands on either side. Such depression was absent or less prominent in unsound seeds. Based on these observations, a reflectance index SQI, abbreviated for seed quality index, was formulated using reflectance at three narrow SWIR wavebands so that it represents the extent of the depression. SQI calculated from seed area-averaged reflectance spectra and spatial distribution patterns of pixelwise SQI within each seed area were both proven as reliable criteria for sound seed selection. Enrichment of sound seeds was accompanied by an increase in germination rate of the seed lot. Thus, the methods described are readily applicable toward low-cost seedling production in combination with single seed sowing technology. PMID:26083366

  14. Observation of short time-scale spectral emissions at millimeter wavelengths with the new CTS diagnostic on the FTU tokamak

    DEFF Research Database (Denmark)

    Bruschi, A.; Alessi, E.; Bin, W.

    2017-01-01

    On the FTU tokamak, the collective Thomson scattering (CTS) diagnostic was renewed for investigating the possible excitation of parametric decay instabilities (PDI) by electron cyclotron (EC) or CTS probe beams in presence of magnetic islands and measure their effects on the EC power absorption...

  15. Infrared Emission from Kilonovae: The Case of the Nearby Short Hard Burst GRB 160821B

    Energy Technology Data Exchange (ETDEWEB)

    Kasliwal, Mansi M.; Lau, Ryan M. [Division of Physics, Mathematics and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Korobkin, Oleg; Wollaeger, Ryan; Fryer, Christopher L. [Computational Methods Group (CCS-2), Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM, 87545 (United States)

    2017-07-10

    We present constraints on Ks-band emission from one of the nearest short hard gamma-ray bursts, GRB 160821B, at z = 0.16, at three epochs. We detect a red relativistic afterglow from the jetted emission in the first epoch but do not detect any excess kilonova emission in the second two epochs. We compare upper limits obtained with Keck I/MOSFIRE to multi-dimensional radiative transfer models of kilonovae, that employ composition-dependent nuclear heating and LTE opacities of heavy elements. We discuss eight models that combine toroidal dynamical ejecta and two types of wind and one model with dynamical ejecta only. We also discuss simple, empirical scaling laws of predicted emission as a function of ejecta mass and ejecta velocity. Our limits for GRB 160821B constrain the ejecta mass to be lower than 0.03 M {sub ⊙} for velocities greater than 0.1 c. At the distance sensitivity range of advanced LIGO, similar ground-based observations would be sufficiently sensitive to the full range of predicted model emission including models with only dynamical ejecta. The color evolution of these models shows that I – K color spans 7–16 mag, which suggests that even relatively shallow infrared searches for kilonovae could be as constraining as optical searches.

  16. Wavelength-tuned light emission via modifying the band edge symmetry: Doped SnO2 as an example

    KAUST Repository

    Zhou, Hang; Deng, Rui; Li, Yongfeng; Yao, Bin; Ding, Zhanhui; Wang, Qingxiao; Han, Yu; Wu, Tao; Liu, Lei

    2014-01-01

    at 398 nm is observed in the indium-doped SnO2-based heterojunction. Our results demonstrate an unprecedented doping-based approach toward tailoring the symmetry of band edge states and recovering ultraviolet light emission in wide-bandgap oxides. © 2014

  17. Wavelength-tuned light emission via modifying the band edge symmetry: Doped SnO2 as an example

    KAUST Repository

    Zhou, Hang

    2014-03-27

    We report the observation of ultraviolet photoluminescence and electroluminescence in indium-doped SnO2 thin films with modified "forbidden" bandgap. With increasing indium concentration in SnO 2, dominant visible light emission evolves into the ultraviolet regime in photoluminescence. Hybrid functional first-principles calculations demonstrate that the complex of indium dopant and oxygen vacancy breaks "forbidden" band gap to form allowed transition states. Furthermore, undoped and 10% indium-doped SnO2 layers are synthesized on p-type GaN substrates to obtain SnO2-based heterojunction light-emitting diodes. A dominant visible emission band is observed in the undoped SnO 2-based heterojunction, whereas strong near-ultraviolet emission peak at 398 nm is observed in the indium-doped SnO2-based heterojunction. Our results demonstrate an unprecedented doping-based approach toward tailoring the symmetry of band edge states and recovering ultraviolet light emission in wide-bandgap oxides. © 2014 American Chemical Society.

  18. Stimulated emission of surface plasmon polaritons by lead-sulphide quantum dots at near infra-red wavelengths

    DEFF Research Database (Denmark)

    Radko, Ilya P.; Nielsen, Michael Grøndahl; Albrektsen, Ole

    2010-01-01

    Amplification of surface plasmon polaritons (SPPs) in planar metal-dielectric structure through stimulated emission is investigated using leakage-radiation microscopy configuration. The gain medium is a thin polymethylmethacrylate layer doped with lead-sulphide nanocrystals emitting at near-infrared...

  19. Solid state cathodoluminescence and the properties of its two emission peaks

    International Nuclear Information System (INIS)

    Xu Xurong

    2007-01-01

    We discovered solid state cathodoluminescence (SSCL). For its identification we excluded all artifacts, carried out its cross proof and studied its generality. Its spectrum is characterized by the appearance of short wavelength peak when the applied voltage is increased. Three voltage ranges are distinguished, in the lower voltage range we have the long wavelength emission, in the middle range we have both long and short wavelength emissions, and in the higher voltage range we have only the short wavelength emission. The mechanism of this spectral shift lies in the electrical field ionization of excitons. This effect initiates the applicability of band model besides molecular excitons theory. The temporal behaviors of both peaks in SSCL are studied with a method of estimating lifetime by means of frequency dependence on intensity. The lifetime of short wavelength emission is found to be 5 ms and that of long wavelength emission is less than 0.05 ms

  20. X-ray emission, ablation pressure, and preheating for foils irradiated at 0. 26. mu. m wavelength

    Energy Technology Data Exchange (ETDEWEB)

    Pepin, H.; Fabbro, R.; Faral, B.; Amiranoff, F.; Virmont, J.; Cottet, F.; Romain, J.P.

    1985-11-01

    The x-ray emission, ablation pressure, and preheating for foils irradiated with a 0.26 ..mu..m laser at intensities approx.10/sup 15/ W cm/sup -2/ are studied. The foils are Al with various thicknesses, coated or uncoated with CH or Au. The x-ray emission and conversion efficiency are obtained with a multichannel x-ray diode spectrometer, the ablation pressures are deduced from shock transit times, and the rear temperatures are inferred from x-ray pyrometry. For thin foils (<<12 ..mu..m), the rear temperatures can be predicted reasonably well with the use of the front x-ray spectra. For thick foils shock preheating is dominant.

  1. X-ray emission, ablation pressure, and preheating for foils irradiated at 0.26 μm wavelength

    International Nuclear Information System (INIS)

    Pepin, H.; Fabbro, R.; Faral, B.; Amiranoff, F.; Virmont, J.; Cottet, F.; Romain, J.P.

    1985-01-01

    The x-ray emission, ablation pressure, and preheating for foils irradiated with a 0.26 μm laser at intensities approx.10 15 W cm -2 are studied. The foils are Al with various thicknesses, coated or uncoated with CH or Au. The x-ray emission and conversion efficiency are obtained with a multichannel x-ray diode spectrometer, the ablation pressures are deduced from shock transit times, and the rear temperatures are inferred from x-ray pyrometry. For thin foils (<<12 μm), the rear temperatures can be predicted reasonably well with the use of the front x-ray spectra. For thick foils shock preheating is dominant

  2. [Effect of different excitation monitoring wavelengths on emission spectrum of red long afterglow phosphor Sr3Al2O6 : Eu2+, Dy3+].

    Science.gov (United States)

    Cui, Cai-e; Li, Jian; Huang, Ping; Liang, Li-ping; Wu, Yin-lan

    2012-01-01

    The Eu2+ and Dy3+ ion co-doped Sr3Al2O6 phosphor powders with long afterglow were prepared with high temperature solid-state reaction. The phase and the spectra properties of the material were characterized by X-ray diffraction (XRD) and fluorescence spectrophotometer. It was found that the sample is composed of pure Sr3Al2O6 phase. Furthermore, the emission peak of 537 nm under 360 nm excitation and that of 590 nm excited by 468 nm-light were obtained, respectively, and it is more interesting that the emission peaks were at 537 and 590 nm under 394 nm excitation. The effects of different excitation wavelengths on the emission spectrum were explained reasonably by the effect of nephelauxetic effect and crystal field. It revealed that the two types of luminescence with different color were caused by the differences of the center of gravity of the 5d excited state energy level and the split range of 5d energy level.

  3. Spectral emissivities at wavelengths in the range 500--653 nm, enthalpies, and heat capacities of the liquid phases of cobalt, titanium, and zirconium

    International Nuclear Information System (INIS)

    Qin, J.; Roesner-Kuhn, M.; Drewes, K.; Thiedemann, U.; Kuppermann, G.; Camin, B.; Blume, R.; Frohberg, M.G.

    1997-01-01

    A review is given of the literature data for spectral emissivities at wavelengths (λ) in the range 500--653 nm, the enthalpies, and heat capacities of the liquid phases of cobalt, titanium, and zirconium. Emissivity measurements were carried out by means of electromagnetic levitation at the solid-to-liquid transition with a partial-radiation pyrometer operating at λ = 547 and 650 nm. Considering the sensitivity of the optical properties to surface impurities, investigations on the surfaces of several titanium and zirconium samples by X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS) were performed that confirmed a nitrogen- and oxygen-free process atmosphere during the measurements. Liquid phase normal emissivities obtained were var-epsilon n,547 = 0.365 and var-epsilon n,650 = 0.331 for cobalt, var-epsilon n,547 = 0.409 and var-epsilon n,650 = 0.393 for titanium, and var-epsilon n,547 = 0.365 and var-epsilon n,650 = 0.355 for zirconium. Enthalpy measurements on the liquid metals were carried out by means of levitation-drop calorimetry in the range 1591--2159 K for cobalt, 1847--2430 K for titanium, and 2025--2897 K for zirconium. The resulting heat capacities (values in J·mol -1 ·K -1 ) obtained were 42.78 for cobalt, 43.79 for titanium, and 39.81 for zirconium

  4. Short pulse laser-induced optical damage and fracto-emission of amorphous, diamond-like carbon

    Energy Technology Data Exchange (ETDEWEB)

    SOKOLOWSKI-TINTEN,K.; VON DER LINDE,D.; SIEGAL,MICHAEL P.; OVERMYER,DONALD L.

    2000-02-07

    Short pulse laser damage and ablation of amorphous, diamond-like carbon films is investigated. Material removal is due to fracture of the film and ejection of large fragments, which exhibit a broadband emission of microsecond duration.

  5. The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites

    Science.gov (United States)

    Priante, D.; Dursun, I.; Alias, M. S.; Shi, D.; Melnikov, V. A.; Ng, T. K.; Mohammed, O. F.; Bakr, O. M.; Ooi, B. S.

    2015-02-01

    We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77 K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic radiative transitions related to grain size inhomogeneity were identified. Both transitions led to PL spectra broadening as a result of concurrent blue and red shifts of these excitonic peaks. The red-shifted bound-excitonic peak dominated at high PL excitation led to a true-green wavelength of 553 nm for CH3NH3PbBr3 powders that are encapsulated in polydimethylsiloxane. Amplified spontaneous emission was eventually achieved for an excitation threshold energy of approximately 350 μJ/cm2. Our results provide a platform for potential extension towards a true-green light-emitting device for solid-state lighting and display applications.

  6. The recombination mechanisms leading to amplified spontaneous emission at the true-green wavelength in CH3NH3PbBr3 perovskites

    KAUST Repository

    Priante, Davide

    2015-02-23

    We investigated the mechanisms of radiative recombination in a CH3NH3PbBr3 hybrid perovskite material using low-temperature, power-dependent (77K), and temperature-dependent photoluminescence (PL) measurements. Two bound-excitonic radiative transitions related to grain size inhomogeneity were identified. Both transitions led to PL spectra broadening as a result of concurrent blue and red shifts of these excitonic peaks. The red-shifted bound-excitonic peak dominated at high PL excitation led to a true-green wavelength of 553nm for CH3NH3PbBr3 powders that are encapsulated in polydimethylsiloxane. Amplified spontaneous emission was eventually achieved for an excitation threshold energy of approximately 350μJ/cm2. Our results provide a platform for potential extension towards a true-green light-emitting device for solid-state lighting and display applications.

  7. Extended wavelength anisotropy resolved multidimensional emission spectroscopy (ARMES) measurements: better filters, validation standards, and Rayleigh scatter removal methods

    Science.gov (United States)

    Casamayou-Boucau, Yannick; Ryder, Alan G.

    2017-09-01

    Anisotropy resolved multidimensional emission spectroscopy (ARMES) provides valuable insights into multi-fluorophore proteins (Groza et al 2015 Anal. Chim. Acta 886 133-42). Fluorescence anisotropy adds to the multidimensional fluorescence dataset information about the physical size of the fluorophores and/or the rigidity of the surrounding micro-environment. The first ARMES studies used standard thin film polarizers (TFP) that had negligible transmission between 250 and 290 nm, preventing accurate measurement of intrinsic protein fluorescence from tyrosine and tryptophan. Replacing TFP with pairs of broadband wire grid polarizers enabled standard fluorescence spectrometers to accurately measure anisotropies between 250 and 300 nm, which was validated with solutions of perylene in the UV and Erythrosin B and Phloxine B in the visible. In all cases, anisotropies were accurate to better than ±1% when compared to literature measurements made with Glan Thompson or TFP polarizers. Better dual wire grid polarizer UV transmittance and the use of excitation-emission matrix measurements for ARMES required complete Rayleigh scatter elimination. This was achieved by chemometric modelling rather than classical interpolation, which enabled the acquisition of pure anisotropy patterns over wider spectral ranges. In combination, these three improvements permit the accurate implementation of ARMES for studying intrinsic protein fluorescence.

  8. Greenhouse gas emissions from short-rotation forestry on a drained and rewetted fen

    Science.gov (United States)

    Schlaipfer, Martina; Fuertes Sánchez, Alicia; Drösler, Matthias

    2017-04-01

    More than 95 % of German peatlands have been drained, primarily for agricultural and forestry use. They constitute a significant source of greenhouse gases (GHG) with emissions of approximately 47 million tons per year. Propelled by the German energy turnaround farmers have increasingly converted their cropland to short rotation forestry (SRF), amongst them some who are cultivating drained peatland. In this study GHG emissions from alder and poplar short rotation plantations with differing groundwater levels near Rosenheim, Bavaria, were monitored over the course of three-and-a-half years. Moreover, the effect of ploughing for SRF establishment was investigated as well. Understorey GHG fluxes were measured using closed-chamber approaches. Gas samples were enclosed in vials every second week and analysed for their CH4 and N2O concentrations by gas chromatography at a laboratory. On-site measurements of CO2 fluxes were carried out over the course of a day every three to four weeks with a dynamic closed-chamber technique. Allometric methods were employed to estimate carbon sequestration into trees. Sheet piling was installed around a set of measurement sites in December 2014 to accentuate the difference between the sites with high and low water tables. As a result the water level around those sites rose from an average of -36.1 ± 6.1 cm in 2013 and 2014 to -20.8 ± 3.7 cm in 2015. The water table outside the sheet piling showed values of -61.8 ± 5.7 cm and -72.1 ± 6.2 cm in those years, respectively. First results suggest a limited effect of ploughing for SRF establishment on understorey GHG emissions. However, there seems to be a distinct impact on tree productivity. CO2 fluxes in the understorey seem to be strongly influenced by water table, but also land management (mulching of understorey vegetation to reduce weed competition for trees during the first year and for pest control in subsequent years) and shading of the understorey vegetation by trees. There is a

  9. Spectral shifts of mammalian ultraviolet-sensitive pigments (short wavelength-sensitive opsin 1) are associated with eye length and photic niche evolution.

    Science.gov (United States)

    Emerling, Christopher A; Huynh, Hieu T; Nguyen, Minh A; Meredith, Robert W; Springer, Mark S

    2015-11-22

    Retinal opsin photopigments initiate mammalian vision when stimulated by light. Most mammals possess a short wavelength-sensitive opsin 1 (SWS1) pigment that is primarily sensitive to either ultraviolet or violet light, leading to variation in colour perception across species. Despite knowledge of both ultraviolet- and violet-sensitive SWS1 classes in mammals for 25 years, the adaptive significance of this variation has not been subjected to hypothesis testing, resulting in minimal understanding of the basis for mammalian SWS1 spectral tuning evolution. Here, we gathered data on SWS1 for 403 mammal species, including novel SWS1 sequences for 97 species. Ancestral sequence reconstructions suggest that the most recent common ancestor of Theria possessed an ultraviolet SWS1 pigment, and that violet-sensitive pigments evolved at least 12 times in mammalian history. We also observed that ultraviolet pigments, previously considered to be a rarity, are common in mammals. We then used phylogenetic comparative methods to test the hypotheses that the evolution of violet-sensitive SWS1 is associated with increased light exposure, extended longevity and longer eye length. We discovered that diurnal mammals and species with longer eyes are more likely to have violet-sensitive pigments and less likely to possess UV-sensitive pigments. We hypothesize that (i) as mammals evolved larger body sizes, they evolved longer eyes, which limited transmittance of ultraviolet light to the retina due to an increase in Rayleigh scattering, and (ii) as mammals began to invade diurnal temporal niches, they evolved lenses with low UV transmittance to reduce chromatic aberration and/or photo-oxidative damage. © 2015 The Author(s).

  10. Short-term variability of mineral dust, metals and carbon emission from road dust resuspension

    Science.gov (United States)

    Amato, Fulvio; Schaap, Martijn; Denier van der Gon, Hugo A. C.; Pandolfi, Marco; Alastuey, Andrés; Keuken, Menno; Querol, Xavier

    2013-08-01

    Particulate matter (PM) pollution in cities has severe impact on morbidity and mortality of their population. In these cities, road dust resuspension contributes largely to PM and airborne heavy metals concentrations. However, the short-term variation of emission through resuspension is not well described in the air quality models, hampering a reliable description of air pollution and related health effects. In this study we experimentally show that the emission strength of resuspension varies widely among road dust components/sources. Our results offer the first experimental evidence of different emission rates for mineral dust, heavy metals and carbon fractions due to traffic-induced resuspension. Also, the same component (or source) recovers differently in a road in Barcelona (Spain) and a road in Utrecht (The Netherlands). This finding has important implications on atmospheric pollution modelling, mostly for mineral dust, heavy metals and carbon species. After rain events, recoveries were generally faster in Barcelona rather than in Utrecht. The largest difference was found for the mineral dust (Al, Si, Ca). Tyre wear particles (organic carbon and zinc) recovered faster than other road dust particles in both cities. The source apportionment of road dust mass provides useful information for air quality management.

  11. Short-Chain Chlorinated Paraffins in Zurich, Switzerland--Atmospheric Concentrations and Emissions.

    Science.gov (United States)

    Diefenbacher, Pascal S; Bogdal, Christian; Gerecke, Andreas C; Glüge, Juliane; Schmid, Peter; Scheringer, Martin; Hungerbühler, Konrad

    2015-08-18

    Short-chain chlorinated paraffins (SCCPs) are of concern due to their potential for adverse health effects, bioaccumulation, persistence, and long-range transport. Data on concentrations of SCCPs in urban areas and underlying emissions are still scarce. In this study, we investigated the levels and spatial distribution of SCCPs in air, based on two separate, spatially resolved sampling campaigns in the city of Zurich, Switzerland. SCCP concentrations in air ranged from 1.8 to 17 ng·m(-3) (spring 2011) and 1.1 to 42 ng·m(-3) (spring 2013) with medians of 4.3 and 2.7 ng·m(-3), respectively. Both data sets show that atmospheric SCCP levels in Zurich can vary substantially and may be influenced by a number of localized sources within this urban area. Additionally, continuous measurements of atmospheric concentrations performed at one representative sampling site in the city center from 2011 to 2013 showed strong seasonal variations with high SCCP concentrations in summer and lower levels in winter. A long-term dynamic multimedia environmental fate model was parametrized to simulate the seasonal trends of SCCP concentrations in air and to back-calculate urban emissions. Resulting annual SCCP emissions in the city of Zurich accounted for 218-321 kg, which indicates that large SCCP stocks are present in urban areas of industrialized countries.

  12. InGaAs/InP quantum wires grown on silicon with adjustable emission wavelength at telecom bands.

    Science.gov (United States)

    Han, Yu; Li, Qiang; Ng, Kar Wei; Zhu, Si; Lau, Kei May

    2018-06-01

    We report the growth of vertically stacked InGaAs/InP quantum wires on (001) Si substrates with adjustable room-temperature emission at telecom bands. Based on a self-limiting growth mode in selective area metal-organic chemical vapor deposition, crescent-shaped InGaAs quantum wires with variable dimensions are embedded within InP nano-ridges. With extensive transmission electron microscopy studies, the growth transition and morphology change from quantum wires to ridge quantum wells (QWs) have been revealed. As a result, we are able to decouple the quantum wires from ridge QWs and manipulate their dimensions by scaling the growth time. With minimized lateral dimension and their unique positioning, the InGaAs/InP quantum wires are more immune to dislocations and more efficient in radiative processes, as evidenced by their excellent optical quality at telecom-bands. These promising results thus highlight the potential of combining low-dimensional quantum wire structures with the aspect ratio trapping process for integrating III-V nano-light emitters on mainstream (001) Si substrates.

  13. Multi-wavelength emission from a single InGaN/GaN nanorod analyzed by cathodoluminescence hyperspectral imaging

    KAUST Repository

    Kusch, Gunnar

    2018-01-23

    Multiple luminescence peaks emitted by a single InGaN/GaN quantum-well(QW) nanorod, extending from the blue to the red, were analysed by a combination of electron microscope based imaging techniques. Utilizing the capability of cathodoluminescence hyperspectral imaging it was possible to investigate spatial variations in the luminescence properties on a nanoscale. The high optical quality of a single GaN nanorod was demonstrated, evidenced by a narrow band-edge peak and the absence of any luminescence associated with the yellow defect band. Additionally two spatially confined broad luminescence bands were observed, consisting of multiple peaks ranging from 395 nm to 480 nm and 490 nm to 650 nm. The lower energy band originates from broad c-plane QWs located at the apex of the nanorod and the higher energy band from the semipolar QWs on the pyramidal nanorod tip. Comparing the experimentally observed peak positions with peak positions obtained from plane wave modelling and 3D finite difference time domain(FDTD) modelling shows modulation of the nanorod luminescence by cavity modes. By studying the influence of these modes we demonstrate that this can be exploited as an additional parameter in engineering the emission profile of LEDs.

  14. Multi-band emission in a wide wavelength range from tin oxide/Au nanocomposites grown on porous anodic alumina substrate (AAO)

    International Nuclear Information System (INIS)

    Norek, Małgorzata; Michalska-Domańska, Marta; Stępniowski, Wojciech J.; Ayala, Israel; Bombalska, Aneta; Budner, Bogusław

    2013-01-01

    The photoluminescence (PL) properties of tin oxide nanostructures are investigated. Three samples of different morphology, induced by deposition process and various geometrical features of nanoporous anodic aluminum oxide (AAO) substrate, are analyzed. X-ray photoelectronic spectroscopy (XPS) analysis reveals the presence of two forms of tin oxide on the surface of all studied samples: SnO and SnO 2 . The former form is typical for reduced surface with bridging oxygen atoms and every other row of in-plane oxygen atoms removed. The oxygen defects give rise to a strong emission in visible region. Two intense PL peaks are observed centered at about 540 (band I) and 620 (band II) nm. The origin of these bands was ascribed to the recombination of electrons from the conduction band (band I) and shallow traps levels (band II) to the surface oxygen vacancy levels. Upon deposition of Au nanoparticles on the top of tin oxide nanostructures the emission at 540 and 620 nm disappears and a new band (band III) occurs in the range >760 nm. The PL mechanism operating in the studied systems is discussed. The tin oxide/Au nanocomposites can be used as efficient multi-band light emitters in a wide (from visible to near infrared) wavelength range.

  15. Short-wavelength multiline erbium-doped fiber ring laser by a broadband long-period fiber grating inscribed in a taper transition

    International Nuclear Information System (INIS)

    Anzueto-Sánchez, G; Martínez-Rios, A

    2014-01-01

    A stable multiwavelength all-fiber erbium-doped fiber ring laser (EDFRL) based on a broadband long-period fiber grating (LPFG) inscribed in a fiber taper transition is presented. The LPFG’s characteristics were engineered to provide a higher loss at the natural lasing wavelength of the laser cavity. The LPFG inscribed on a taper transition provided a depth greater than 25 dB, and posterior chemical etching provided a broad notch band to inhibit laser generation on the long-wavelength side of the EDF gain. Up to four simultaneous laser wavelengths are generated in the range of 1530–1535 nm. (paper)

  16. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  17. Fine tuning the emission wavelengths of the 7-hydroxy-1-indanone based nano-structure dyes: Near-infrared (NIR) dual emission generation with large stokes shifts

    Science.gov (United States)

    Roohi, Hossein; Alizadeh, Parvaneh

    2018-05-01

    Near-infrared (NIR) fluorescent dyes have recently gained special attention due to their applications to use as molecular probes for imaging of biological targets and sensitive determination. In this study, photophysical properties of the 7-hydroxy-1-indanone based fluorophors A1, A2, A3, B1, B2 and 3R-B2 (R = CF3, NH2, NO2 and OMe) in the gas and three solution phases were probed using TD-DFT method at PBE0/6-311++G(d,p) and M06-2X/6-311++G(d,p) levels of theory. In addition to structural and photophysical properties as well as ESIPT mechanism of all mentioned molecules, the FC and relaxed potential energy surfaces of B2 and 3R-B2 (R = CF3 and NH2) molecules were explored in gas phase and acetonitrile, cyclohexane and water solvents. It is predicted that the A1, A3 and 3R-B2 chromophores afford normal (615-670 nm) and NIR fluorescence emissions (770-940 nm; biological window) with the large Stokes shifts of >160 and >300 nm, respectively. A good aggrement was found between theoretical and experimental results. In sum, these new types of dyes may render the new approaches for the development of the most efficient NIR fluorescent probes for enhanced image contrast and optimal apparent brightness in biological applications.

  18. The potential for short-rotation woody crops to reduce US CO2 emissions

    International Nuclear Information System (INIS)

    Graham, R.L.; Wright, L.L.; Turhollow, A.F.

    1992-01-01

    Short-rotation woody crops (SRWC) could potentially displace fossil fuels and thus mitigate CO 2 buildup in the atmosphere. To determine how much fossil fuel SRWC might displace in the United States and what the associated fossil carbon savings might be, a series of assumptions must be made. These assumptions concern the net SRWC biomass yields per hectare (after losses); the amount of suitable land dedicated to SRWC production; wood conversion efficiencies to electricity or liquid fuels; the energy substitution properties of various fuels; and the amount of fossil fuel used in growing, harvesting, transporting, and converting SRWC biomass. Assuming the current climate, present production, and conversion technologies and considering a conservative estimate of the US land base available for SRWC (14 x 10 6 ha), it is calculated that SRWC energy could displace 33.2 to 73.1 x 10 6 Mg of fossil carbon releases, 3-6% of the current annual US emissions. The carbon mitigation potential per unit of land is larger with the substitution of SRWC for coal-based electricity production than for the substitution of SRWC-derived ethanol for gasoline. Assuming current climate, predicted conversion technology advancements, an optimistic estimate of the US land base available for SRWC (28 x 10 6 ha), and an optimistic average estimate of net SRWC yields (22.4 dry Mg/ha), it is calculate that SRWC energy could displace 148 to 242 x 10 6 Mg of annual fossil fuel carbon releases. Under this scenario, the carbon migration potential of SRWC-based electricity production would be equivalent to about 4.4% of current global fossil fuel emissions and 20% of current US fossil fuel emissions. 21 refs., 5 tabs

  19. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Directory of Open Access Journals (Sweden)

    Rueda J. A.

    2018-01-01

    Full Text Available We have sub-classified short and long-duration gamma-ray bursts (GRBs into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS or neutron star-black hole binaries (NS-BH. Long GRBs are produced via the induced gravitational collapse (IGC scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore and a NS companion. The COcore explodes as type Ic supernova (SN leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1 the role of the NS structure and the nuclear equation of state; 2 the occurrence rates obtained from X and gamma-rays observations; 3 the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  20. The binary progenitors of short and long GRBs and their gravitational-wave emission

    Science.gov (United States)

    Rueda, J. A.; Ruffini, R.; Rodriguez, J. F.; Muccino, M.; Aimuratov, Y.; Barres de Almeida, U.; Becerra, L.; Bianco, C. L.; Cherubini, C.; Filippi, S.; Kovacevic, M.; Moradi, R.; Pisani, G. B.; Wang, Y.

    2018-01-01

    We have sub-classified short and long-duration gamma-ray bursts (GRBs) into seven families according to the binary nature of their progenitors. Short GRBs are produced in mergers of neutron-star binaries (NS-NS) or neutron star-black hole binaries (NS-BH). Long GRBs are produced via the induced gravitational collapse (IGC) scenario occurring in a tight binary system composed of a carbon-oxygen core (COcore) and a NS companion. The COcore explodes as type Ic supernova (SN) leading to a hypercritical accretion process onto the NS: if the accretion is sufficiently high the NS reaches the critical mass and collapses forming a BH, otherwise a massive NS is formed. Therefore long GRBs can lead either to NS-BH or to NS-NS binaries depending on the entity of the accretion. We discuss for the above compact-object binaries: 1) the role of the NS structure and the nuclear equation of state; 2) the occurrence rates obtained from X and gamma-rays observations; 3) the predicted annual number of detections by the Advanced LIGO interferometer of their gravitational-wave emission.

  1. Simultaneous detection of electronic structure changes from two elements of a bifunctional catalyst using wavelength-dispersive X-ray emission spectroscopy and in situ electrochemistry.

    Science.gov (United States)

    Gul, Sheraz; Ng, Jia Wei Desmond; Alonso-Mori, Roberto; Kern, Jan; Sokaras, Dimosthenis; Anzenberg, Eitan; Lassalle-Kaiser, Benedikt; Gorlin, Yelena; Weng, Tsu-Chien; Zwart, Petrus H; Zhang, Jin Z; Bergmann, Uwe; Yachandra, Vittal K; Jaramillo, Thomas F; Yano, Junko

    2015-04-14

    Multielectron catalytic reactions, such as water oxidation, nitrogen reduction, or hydrogen production in enzymes and inorganic catalysts often involve multimetallic clusters. In these systems, the reaction takes place between metals or metals and ligands to facilitate charge transfer, bond formation/breaking, substrate binding, and release of products. In this study, we present a method to detect X-ray emission signals from multiple elements simultaneously, which allows for the study of charge transfer and the sequential chemistry occurring between elements. Kβ X-ray emission spectroscopy (XES) probes charge and spin states of metals as well as their ligand environment. A wavelength-dispersive spectrometer based on the von Hamos geometry was used to disperse Kβ signals of multiple elements onto a position detector, enabling an XES spectrum to be measured in a single-shot mode. This overcomes the scanning needs of the scanning spectrometers, providing data free from temporal and normalization errors and therefore ideal to follow sequential chemistry at multiple sites. We have applied this method to study MnOx-based bifunctional electrocatalysts for the oxygen evolution reaction (OER) and the oxygen reduction reaction (ORR). In particular, we investigated the effects of adding a secondary element, Ni, to form MnNiOx and its impact on the chemical states and catalytic activity, by tracking the redox characteristics of each element upon sweeping the electrode potential. The detection scheme we describe here is general and can be applied to time-resolved studies of materials consisting of multiple elements, to follow the dynamics of catalytic and electron transfer reactions.

  2. CO2 emissions and economic activity: Short- and long-run economic determinants of scale, energy intensity and carbon intensity

    International Nuclear Information System (INIS)

    Andersson, Fredrik N.G.; Karpestam, Peter

    2013-01-01

    We analyze the short-term and the long-term determinants of energy intensity, carbon intensity and scale effects for eight developed economies and two emerging economies from 1973 to 2007. Our results show that there is a difference between the short-term and the long-term results and that climate policy are more likely to affect emission over the long-term than over the short-term. Climate policies should therefore be aimed at a time horizon of at least 8 years and year-on-year changes in emissions contains little information about the trend path of emissions. In the long-run capital accumulation is the main driver of emissions. Productivity growth reduces the energy intensity while the real oil price reduces both the energy intensity and the carbon intensity. The real oil price effect suggests that a global carbon tax is an important policy tool to reduce emissions, but our results also suggest that a carbon tax is likely to be insufficient decouple emission from economic growth. Such a decoupling is likely to require a structural transformation of the economy. The key policy challenge is thus to build new economic structures where investments in green technologies are more profitable. - Highlights: • We model determinants of scale, energy intensity and carbon intensity. • Using band spectrum regressions, we separate between short and long run effects. • Different economic variables affect emission in the short and long run. • CO 2 reducing policies should have a long run horizon of (at least 8 years). • A low carbon society requires a structural transformation of the economy

  3. Field trial of a dual-wavelength fluorescent emission (L.I.F.E.) instrument and the Magma White rover during the MARS2013 Mars analog mission.

    Science.gov (United States)

    Groemer, Gernot; Sattler, Birgit; Weisleitner, Klemens; Hunger, Lars; Kohstall, Christoph; Frisch, Albert; Józefowicz, Mateusz; Meszyński, Sebastian; Storrie-Lombardi, Michael; Bothe, Claudia; Boyd, Andrea; Dinkelaker, Aline; Dissertori, Markus; Fasching, David; Fischer, Monika; Föger, Daniel; Foresta, Luca; Frischauf, Norbert; Fritsch, Lukas; Fuchs, Harald; Gautsch, Christoph; Gerard, Stephan; Goetzloff, Linda; Gołebiowska, Izabella; Gorur, Paavan; Groemer, Gerhard; Groll, Petra; Haider, Christian; Haider, Olivia; Hauth, Eva; Hauth, Stefan; Hettrich, Sebastian; Jais, Wolfgang; Jones, Natalie; Taj-Eddine, Kamal; Karl, Alexander; Kauerhoff, Tilo; Khan, Muhammad Shadab; Kjeldsen, Andreas; Klauck, Jan; Losiak, Anna; Luger, Markus; Luger, Thomas; Luger, Ulrich; McArthur, Jane; Moser, Linda; Neuner, Julia; Orgel, Csilla; Ori, Gian Gabriele; Paternesi, Roberta; Peschier, Jarno; Pfeil, Isabella; Prock, Silvia; Radinger, Josef; Ragonig, Christoph; Ramirez, Barbara; Ramo, Wissam; Rampey, Mike; Sams, Arnold; Sams, Elisabeth; Sams, Sebastian; Sandu, Oana; Sans, Alejandra; Sansone, Petra; Scheer, Daniela; Schildhammer, Daniel; Scornet, Quentin; Sejkora, Nina; Soucek, Alexander; Stadler, Andrea; Stummer, Florian; Stumptner, Willibald; Taraba, Michael; Tlustos, Reinhard; Toferer, Ernst; Turetschek, Thomas; Winter, Egon; Zanella-Kux, Katja

    2014-05-01

    Abstract We have developed a portable dual-wavelength laser fluorescence spectrometer as part of a multi-instrument optical probe to characterize mineral, organic, and microbial species in extreme environments. Operating at 405 and 532 nm, the instrument was originally designed for use by human explorers to produce a laser-induced fluorescence emission (L.I.F.E.) spectral database of the mineral and organic molecules found in the microbial communities of Earth's cryosphere. Recently, our team had the opportunity to explore the strengths and limitations of the instrument when it was deployed on a remote-controlled Mars analog rover. In February 2013, the instrument was deployed on board the Magma White rover platform during the MARS2013 Mars analog field mission in the Kess Kess formation near Erfoud, Morocco. During these tests, we followed tele-science work flows pertinent to Mars surface missions in a simulated spaceflight environment. We report on the L.I.F.E. instrument setup, data processing, and performance during field trials. A pilot postmission laboratory analysis determined that rock samples acquired during the field mission exhibited a fluorescence signal from the Sun-exposed side characteristic of chlorophyll a following excitation at 405 nm. A weak fluorescence response to excitation at 532 nm may have originated from another microbial photosynthetic pigment, phycoerythrin, but final assignment awaits development of a comprehensive database of mineral and organic fluorescence spectra. No chlorophyll fluorescence signal was detected from the shaded underside of the samples.

  4. Short-pulse-laser-induced optical damage and fracto-emission of amorphous, diamond-like carbon films

    Science.gov (United States)

    Sokolowski-Tinten, Klaus; Ziegler, Wolfgang; von der Linde, Dietrich; Siegal, Michael P.; Overmyer, D. L.

    2005-03-01

    Short-pulse-laser-induced damage and ablation of thin films of amorphous, diamond-like carbon have been investigated. Material removal and damage are caused by fracture of the film and ejection of large fragments. The fragments exhibit a delayed, intense and broadband emission of microsecond duration. Both fracture and emission are attributed to the laser-initiated relaxation of the high internal stresses of the pulse laser deposition-grown films.

  5. Mechanism of wavelength conversion in polystyrene doped with benzoxanthene: emergence of a complex.

    Science.gov (United States)

    Nakamura, Hidehito; Shirakawa, Yoshiyuki; Kitamura, Hisashi; Sato, Nobuhiro; Shinji, Osamu; Saito, Katashi; Takahashi, Sentaro

    2013-01-01

    Fluorescent guest molecules doped in polymers have been used to convert ultraviolet light into visible light for applications ranging from optical fibres to filters for the cultivation of plants. The wavelength conversion process involves the absorption of light at short wavelengths followed by fluorescence emission at a longer wavelength. However, a precise understanding of the light conversion remains unclear. Here we show light responses for a purified polystyrene base substrates doped with fluorescent benzoxanthene in concentrations varied over four orders of magnitude. The shape of the excitation spectrum for fluorescence emission changes significantly with the concentration of the benzoxanthene, indicating formation of a base substrate/fluorescent molecule complex. Furthermore, the wavelength conversion light yield increases in three stages depending on the nature of the complex. These findings identify a mechanism that will have many applications in wavelength conversion materials.

  6. InP-InxGa1-xAs core-multi-shell nanowire quantum wells with tunable emission in the 1.3-1.55 μm wavelength range.

    Science.gov (United States)

    Fonseka, H A; Ameruddin, A S; Caroff, P; Tedeschi, D; De Luca, M; Mura, F; Guo, Y; Lysevych, M; Wang, F; Tan, H H; Polimeni, A; Jagadish, C

    2017-09-21

    The usability and tunability of the essential InP-InGaAs material combination in nanowire-based quantum wells (QWs) are assessed. The wurtzite phase core-multi-shell InP-InGaAs-InP nanowire QWs are characterised using cross-section transmission electron microscopy and photoluminescence measurements. The InP-InGaAs direct interface is found to be sharp while the InGaAs-InP inverted interface is more diffused, in agreement with their planar counterpart. Bright emission is observed from the single nanowires containing the QWs at room temperature, with no emission from the InP core or outer barrier. The tunability of the QW emission wavelength in the 1.3-1.55 μm communication wavelength range is demonstrated by varying the QW thickness and in the 1.3 μm range by varying the composition. The experiments are supported by simulation of the emission wavelength of the wurtzite phase InP-InGaAs QWs in the thickness range considered. The radial heterostructure is further extended to design multiple QWs with bright emission, therefore establishing the capability of this material system for nanowire based optical devices for communication applications.

  7. Prediction of short-term and long-term VOC emissions from SBR bitumen-backed carpet under different temperatures

    NARCIS (Netherlands)

    Yang, X.; Chen, Q.; Bluyssen, P.M.

    1998-01-01

    This paper presents two models for volatile organic compound (VOC) emissions from carpet. One is a numerical model using the computational fluid dynamics (CFD) tech-nique for short-term predictions, the other an analytical model for long-term predictions. The numerical model can (1) deal with

  8. Alternative short tests for inspection and maintenance of in-use cars with respect to their emissions performance

    NARCIS (Netherlands)

    Samaras, Z.; Zachariadis, T.; Joumard, R.; Vernet, I.; Hassel, D.; Weber, F.-J.; Rijkeboer, R.C.

    1998-01-01

    This paper presents the first results of a project aimed at evaluation of a number of short tests that can be alternatively used for Inspection and Maintenance of in-use cars emissions performance. For this purpose, a large number of in-use cars from four European countries was tested according to a

  9. Wavelength standards in the infrared

    CERN Document Server

    Rao, KN

    2012-01-01

    Wavelength Standards in the Infrared is a compilation of wavelength standards suitable for use with high-resolution infrared spectrographs, including both emission and absorption standards. The book presents atomic line emission standards of argon, krypton, neon, and xenon. These atomic line emission standards are from the deliberations of Commission 14 of the International Astronomical Union, which is the recognized authority for such standards. The text also explains the techniques employed in determining spectral positions in the infrared. One of the techniques used includes the grating con

  10. Short-Lived Buildings in China: Impacts on Water, Energy, and Carbon Emissions.

    Science.gov (United States)

    Cai, Wenjia; Wan, Liyang; Jiang, Yongkai; Wang, Can; Lin, Lishen

    2015-12-15

    This paper has changed the vague understanding that "the short-lived buildings have huge environmental footprints (EF)" into a concrete one. By estimating the annual floor space of buildings demolished and calibrating the average building lifetime in China, this paper compared the EF under various assumptive extended buildings' lifetime scenarios based on time-series environmental-extended input-output model. Results show that if the average buildings' lifetime in China can be extended from the current 23.2 years to their designed life expectancy, 50 years, in 2011, China can reduce 5.8 Gt of water withdrawal, 127.1 Mtce of energy consumption, and 426.0 Mt of carbon emissions, each of which is equivalent to the corresponding annual EF of Belgium, Mexico, and Italy. These findings will urge China to extend the lifetime of existing and new buildings, in order to reduce the EF from further urbanization. This paper also verifies that the lifetime of a product or the replacement rate of a sector is a very important factor that influences the cumulative EF. When making policies to reduce the EF, adjusting people's behaviors to extend the lifetime of products or reduce the replacement rate of sectors may be a very simple and cost-effective option.

  11. Emission channeling with short-lived isotopes lattice location of impurities in semiconductors and oxides

    CERN Multimedia

    We propose to perform emission channeling lattice location experiments in a number of semiconductor and oxide systems of technological relevance: \\\\- The lattice location of the transition metal probes $^{56}$Mn ($\\textit{t}_{1/2}$=2.6 h), $^{59}$Fe (45 d), $^{61}$Co (1.6 h) and $^{65}$Ni (2.5 h) is to be investigated in materials of interest as dilute magnetic semiconductors, such as GaMnAs, GaMnN, GaFeN, AlGaN, SiC, and in a number of oxides that are candidates for “single ion ferromagnetism”, in particular SrTiO$_3$ and LiNbO$_3$.\\\\- The topic of $\\textit{p}$-type doping of nitride semiconductors shall be addressed by studying the lattice sites of the acceptor dopants Mg and Be in GaN and AlN using the short-lived probes $^{27}$Mg (9.5 min) and $^{11}$Be (13.8 s). The aim is to reach a lattice location precision around 0.05 Å in order to provide critical tests for recent theoretical models which e.g. have predicted displacements of the Mg atom from the ideal substitutional Ga and Al sites of the order...

  12. [Effect of short-time drought process on denitrifying bacteria abundance and N2O emission in paddy soil].

    Science.gov (United States)

    Lu, Jing; Liu, Jin-Bo; Sheng, Rong; Liu, Yi; Chen, An-Lei; Wei, Wen-Xue

    2014-10-01

    In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting-drying process was simulated in laboratory conditions. N2O flux, redox potential (Eh) were monitored and narG- and nosZ-containing denitrifiers abundances were determined by real-time PCR. N2O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h. In addition, narG and nosZ gene abundances were increased rapidly with the drying process, and N2O emission flux was significantly correlated with narG gene abundance (P driving microorganisms which caused the N2O emission in the short-time drought process in paddy soil.

  13. On the high characteristic temperature of an InAs/GaAs/InGaAsP QD laser with an emission wavelength of ~1.5 μm on an InP substrate

    DEFF Research Database (Denmark)

    Zubov, F.; Semenova, Elizaveta; Kulkova, Irina

    2017-01-01

    We report on a study of lasers with an emission wavelength of about 1.5 μm and high temperature stability, synthesized on an InP (001) substrate. Self-organized InAs quantum dots capped with a thin GaAs layer are used as the active region of the laser. A quaternary InGaAsP solid solution with a b......We report on a study of lasers with an emission wavelength of about 1.5 μm and high temperature stability, synthesized on an InP (001) substrate. Self-organized InAs quantum dots capped with a thin GaAs layer are used as the active region of the laser. A quaternary InGaAsP solid solution...

  14. Correlated X-ray/UV/optical emission and short-term variability in a Seyfert 1 galaxy NGC 4593

    Science.gov (United States)

    Pal, Main; Naik, Sachindra

    2018-03-01

    We present a detailed multifrequency analysis of an intense monitoring programme of Seyfert 1 galaxy NGC 4593 over a duration of nearly for a month with Swift observatory. We used 185 pointings to study the variability in six ultraviolet/optical and two soft (0.3-1.5 keV) and hard X-ray (1.5-10 keV) bands. The amplitude of the observed variability is found to decrease from high energy to low energy (X-ray to optical) bands. Count-count plots of ultraviolet/optical bands with hard X-rays clearly suggest the presence of a mixture of two major components: (i) highly variable component such as hard X-ray emission, and (ii) slowly varying disc-like component. The variations observed in the ultraviolet/optical emission are strongly correlated with the hard X-ray band. Cross-correlation analysis provides the lags for the longer wavelengths compared to the hard X-rays. Such lags clearly suggest that the changes in the ultraviolet/optical bands follow the variations in the hard X-ray band. This implies that the observed variation in longer wavelengths is due to X-ray reprocessing. Though, the measured lag spectrum (lag versus wavelength) is well described by λ4/3 as expected from the standard disc model, the observed lags are found to be longer than the predicted values from standard disc model. This implies that the actual size of the disc of NGC 4593 is larger than the estimated size of standard thin disc as reported in active galactic nuclei such as NGC 5548 and Fairall 9.

  15. Sub-wavelength plasmon laser

    Science.gov (United States)

    Bora, Mihail; Bond, Tiziana C.

    2016-04-19

    A plasmonic laser device has resonant nanocavities filled with a gain medium containing an organic dye. The resonant plasmon frequencies of the nanocavities are tuned to align with both the absorption and emission spectra of the dye. Variables in the system include the nature of the dye and the wavelength of its absorption and emission, the wavelength of the pumping radiation, and the resonance frequencies of the nanocavities. In addition the pumping frequency of the dye is selected to be close to the absorption maximum.

  16. High-energy Neutrino Emission from Short Gamma-Ray Bursts: Prospects for Coincident Detection with Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Shigeo S.; Murase, Kohta; Mészáros, Peter [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Kiuchi, Kenta [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto, Kyoto 606-8502 (Japan)

    2017-10-10

    We investigate current and future prospects for coincident detection of high-energy neutrinos and gravitational waves (GWs). Short gamma-ray bursts (SGRBs) are believed to originate from mergers of compact star binaries involving neutron stars. We estimate high-energy neutrino fluences from prompt emission, extended emission (EE), X-ray flares, and plateau emission, and we show that neutrino signals associated with the EE are the most promising. Assuming that the cosmic-ray loading factor is ∼10 and the Lorentz factor distribution is lognormal, we calculate the probability of neutrino detection from EE by current and future neutrino detectors, and we find that the quasi-simultaneous detection of high-energy neutrinos, gamma-rays, and GWs is possible with future instruments or even with current instruments for nearby SGRBs having EE. We also discuss stacking analyses that will also be useful with future experiments such as IceCube-Gen2.

  17. Dry Matter Losses and Greenhouse Gas Emissions From Outside Storage of Short Rotation Coppice Willow Chip.

    Science.gov (United States)

    Whittaker, Carly; Yates, Nicola E; Powers, Stephen J; Misselbrook, Tom; Shield, Ian

    This study examined the dry matter losses and the greenhouse gas (GHG) concentrations within two short rotation coppice (SRC) willow wood chip storage heaps. One heap was built on a grassland area (East Midlands) and the other (Rothamsted) on a concrete hard standing. A series of 1- and 3-m probes were embedded in the heaps in order to retrieve gas samples for analysis, and pre-weighed net bags were positioned in the core of the heap to detect dry matter losses. The bagged samples showed dry matter losses of 18 and 19 % in the East Midlands and Rothamsted heaps after 210 and 97 days storage, respectively. The Rothamsted heap showed a whole-heap dry matter loss of 21 %. During this time, the wood chips dried from 54 to 39 % moisture content in the East Midlands heap and 50 to 43 % at Rothamsted. The results from analysing the whole Rothamsted heap indicated an overall loss of 1.5 GJ per tonne stored, although measurements from bagged samples in the core suggested that the chips dried sufficiently to have a minimal energy loss from storage. The process of mixing the heap, however, led to incorporation of wet outer layers and hence the average moisture content was higher in an average sample of chip. After establishment of the heaps, the temperature rose rapidly and this correlated with a peak in carbon dioxide (CO 2 ) concentration within the heap. A peak in methane (CH 4 ) concentration was also detected in both heaps, though more noticeably in the East Midlands heap after around 55 days. In both instances, the peak CH 4 concentration occurred as CO 2 concentrations dropped, suggesting that after an active period of aerobic decomposition in the first 2 months of storage, the conditions in the heap became anaerobic. The results from this study suggest that outside wood chip storage is not an efficient method of storing biomass, though this may be location-specific as there are some studies showing lower dry matter losses. It is necessary to explore other

  18. Transpiration directly regulates the emissions of water-soluble short-chained OVOCs.

    Science.gov (United States)

    Rissanen, K; Hölttä, T; Bäck, J

    2018-04-20

    Most plant-based emissions of volatile organic compounds (VOCs) are considered mainly temperature dependent. However, certain oxygenated VOCs (OVOCs) have high water solubility; thus, also stomatal conductance could regulate their emissions from shoots. Due to their water solubility and sources in stem and roots, it has also been suggested that their emissions could be affected by transport in xylem sap. Yet, further understanding on the role of transport has been lacking until present. We used shoot-scale long-term dynamic flux data from Scots pines (Pinus sylvestris) to analyse the effects of transpiration and transport in xylem sap flow on emissions of three water soluble OVOC: methanol, acetone and acetaldehyde. We found a direct effect of transpiration on the shoot emissions of the three OVOCs. The emissions were best explained by a regression model that combined linear transpiration and exponential temperature effects. In addition, a structural equation model indicated that stomatal conductance affects emissions mainly indirectly, by regulating transpiration. A part of temperature's effect is also indirect. The tight coupling of shoot emissions to transpiration clearly evidences that these OVOCs are transported in xylem sap from their sources in roots and stem to leaves and to ambient air. This article is protected by copyright. All rights reserved.

  19. Constraints on the optical afterglow emission of the short/hard burst GRB 010119

    DEFF Research Database (Denmark)

    Gorosabel, J.; Andersen, M.I.; Hjorth, J.

    2002-01-01

    We report optical observations of the short/hard burst GRB 010119 error box, one of the smallest error boxes reported to date for short/hard GRBs. Limits of R >22.3 and I >21.2 are imposed by observations carried out 20.31 and 20.58 hours after the gamma-ray event, respectively. They represent th...

  20. Centuries of thermal sea-level rise due to anthropogenic emissions of short-lived greenhouse gases.

    Science.gov (United States)

    Zickfeld, Kirsten; Solomon, Susan; Gilford, Daniel M

    2017-01-24

    Mitigation of anthropogenic greenhouse gases with short lifetimes (order of a year to decades) can contribute to limiting warming, but less attention has been paid to their impacts on longer-term sea-level rise. We show that short-lived greenhouse gases contribute to sea-level rise through thermal expansion (TSLR) over much longer time scales than their atmospheric lifetimes. For example, at least half of the TSLR due to increases in methane is expected to remain present for more than 200 y, even if anthropogenic emissions cease altogether, despite the 10-y atmospheric lifetime of this gas. Chlorofluorocarbons and hydrochlorofluorocarbons have already been phased out under the Montreal Protocol due to concerns about ozone depletion and provide an illustration of how emission reductions avoid multiple centuries of future TSLR. We examine the "world avoided" by the Montreal Protocol by showing that if these gases had instead been eliminated in 2050, additional TSLR of up to about 14 cm would be expected in the 21st century, with continuing contributions lasting more than 500 y. Emissions of the hydrofluorocarbon substitutes in the next half-century would also contribute to centuries of future TSLR. Consideration of the time scales of reversibility of TSLR due to short-lived substances provides insights into physical processes: sea-level rise is often assumed to follow air temperature, but this assumption holds only for TSLR when temperatures are increasing. We present a more complete formulation that is accurate even when atmospheric temperatures are stable or decreasing due to reductions in short-lived gases or net radiative forcing.

  1. Short-run allocation of emissions allowances and long-term goals for climate policy

    NARCIS (Netherlands)

    Zetterberg, Lars; Wråke, Markus; Sterner, Thomas; Fischer, Carolyn; Burtraw, Dallas

    We use economic analysis to evaluate grandfathering, auctioning, and benchmarking approaches for allocation of emissions allowances and then discuss practical experience from European and American schemes. In principle, auctions are superior from the viewpoints of efficiency, fairness, transparency,

  2. Short-term emissions of ammonia and carbon dioxide from cattle urine contaminated tropical grassland microcosm.

    Science.gov (United States)

    Majumdar, Deepanjan; Patel, Manoj; Drabar, Reena; Vyas, Manish

    2006-11-01

    The study was designed to understand the emissions of ammonia (NH(3)) and carbon dioxide (CO(2)) from a single cattle urination event on a tropical grassland and underline the significance of the emissions in the context of huge animal population grazing on large pasture areas in some countries. Emissions of ammonia (NH(3)) and carbon dioxide (CO(2)) were monitored for three weeks from a tropical grassland (dominated by Cynodon dactylon Pers.) microcosm contaminated with cow and buffalo urine. The grassland microcosms were treated with urine (50 and 100 ml of each) only once and irrigated with water once every week. Ammonia was sampled by an automatic sampling system comprising of a vacuum pump, three-way stopcocks and rubber tubing and an impinger containing suitable absorbing solution (H(2)SO(4)), connected to the tubing suitably. The sampled gas, after sucked by the vacuum pump and absorbed in H(2)SO(4), was allowed to enter the closed microcosm again maintaining internal pressure of the microcosm. Carbon dioxide was sampled by absorption in an alkali (NaOH) trap inside the microcosm. Both NH(3) and CO(2) emissions were highly variable temporally and there was no continuous increasing or decreasing emission trend with time. Respectively, 45 and 46% of total NH(3)-N were emitted within first 48 h from 50 and 100 ml cow urine application while the corresponding values for buffalo urine were 34 and 32%. Total NH(3)-N emissions, integrated for sampling days (i.e. 1, 2, 3, 4, 6, 15, 18 and 21st) were 11 and 6% in cow and 8 and 5% in buffalo urine, of the total-N added through 50 and 100 ml urine samples. Carbon dioxide emissions were standardized at 25 degrees C by using a suitable formula which were lower than actual emissions at actual soil temperature (> 25 degrees C). Carbon dioxide emission rates were classified on the basis of soil repiratory classification and classes ranged from moderately low soil activity up to unusually high soil activity, the latter

  3. Soil greenhouse gas emissions and carbon budgeting in a short-hydroperiod floodplain wetland

    Science.gov (United States)

    Batson, Jackie; Noe, Gregory B.; Hupp, Cliff R.; Krauss, Ken W.; Rybicki, Nancy B.; Schenk, Edward R.

    2015-01-01

    Understanding the controls on floodplain carbon (C) cycling is important for assessing greenhouse gas emissions and the potential for C sequestration in river-floodplain ecosystems. We hypothesized that greater hydrologic connectivity would increase C inputs to floodplains that would not only stimulate soil C gas emissions but also sequester more C in soils. In an urban Piedmont river (151 km2 watershed) with a floodplain that is dry most of the year, we quantified soil CO2, CH4, and N2O net emissions along gradients of floodplain hydrologic connectivity, identified controls on soil aerobic and anaerobic respiration, and developed a floodplain soil C budget. Sites were chosen along a longitudinal river gradient and across lateral floodplain geomorphic units (levee, backswamp, and toe slope). CO2 emissions decreased downstream in backswamps and toe slopes and were high on the levees. CH4 and N2O fluxes were near zero; however, CH4emissions were highest in the backswamp. Annual CO2 emissions correlated negatively with soil water-filled pore space and positively with variables related to drier, coarser soil. Conversely, annual CH4 emissions had the opposite pattern of CO2. Spatial variation in aerobic and anaerobic respiration was thus controlled by oxygen availability but was not related to C inputs from sedimentation or vegetation. The annual mean soil CO2 emission rate was 1091 g C m−2 yr−1, the net sedimentation rate was 111 g C m−2 yr−1, and the vegetation production rate was 240 g C m−2 yr−1, with a soil C balance (loss) of −338 g C m−2 yr−1. This floodplain is losing C likely due to long-term drying from watershed urbanization.

  4. Extended wavelength InGaAs on GaAs using InAlAs buffer for back-side-illuminated short-wave infrared detectors

    International Nuclear Information System (INIS)

    Zimmermann, Lars; John, Joachim; Degroote, Stefan; Borghs, Gustaaf; Hoof, Chris van; Nemeth, Stefan

    2003-01-01

    We conducted an experimental study of back-side-illuminated InGaAs photodiodes grown on GaAs and sensitive in the short-wave infrared up to 2.4 μm. Standard metamorphic InGaAs or IR-transparent InAlAs buffers were grown by molecular-beam epitaxy. We studied dark current and photocurrent as a function of buffer thickness, buffer material, and temperature. A saturation of the dark current with buffer thickness was not observed. The maximum resistance area product was ∼10 Ω cm2 at 295 K. The dark current above 200 K was dominated by generation-recombination current. A pronounced dependence of the photocurrent on the buffer thickness was observed. The peak external quantum efficiency was 46% (at 1.6 μm) without antireflective coating

  5. Influence of barrier layer indium on efficiency and wavelength of InGaN multiple quantum well (MQW) with and without semi-bulk InGaN buffer for blue to green regime emission

    Energy Technology Data Exchange (ETDEWEB)

    Alam, Saiful [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Georgia Tech-CNRS, UMI 2958, Metz (France); CEA-LETI, Minatec Campus, Grenoble (France); Sundaram, Suresh; Li, Xin; El Gmili, Youssef [Georgia Tech-CNRS, UMI 2958, Metz (France); Jamroz, Miryam E.; Robin, Ivan C. [CEA-LETI, Minatec Campus, Grenoble (France); Voss, Paul L.; Ougazzaden, Abdallah [School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA (United States); Georgia Tech-CNRS, UMI 2958, Metz (France); Salvestrini, Jean-Paul [Georgia Tech-CNRS, UMI 2958, Metz (France); LMOPS, University of Lorraine, EA4423, Metz (France)

    2017-08-15

    The effect of indium (In) in the barrier of InGaN/GaN multiple quantum well (MQW) has been studied for MQWs with and without semi-bulk InGaN buffer. From simulation, the optimum In content in the barrier with 3-5 nm width is 5-7% to get the optimal material quality and internal quantum efficiency (IQE) of ∝65% for 450-480 nm emission range. Simulation shows a reduction of the potential barrier due to band flattening, a more homogeneous distribution of electrons and holes in the active region and subsequently, a more radiative recombination rate with InGaN as barrier layer. Both cathodoluminescence (CL) and photoluminescence (PL) experimental results show a blue-shift of emission wavelength along with an enhancement in the emission intensity when GaN barrier is replaced with InGaN barrier, for a MQW structure both with and without the semi-bulk InGaN buffer. We attribute this blue shift to the reduced polarization mismatch and increased effective bandgap. This InGaN barrier-related improvement in IQE and efficiency droop could be useful for the realization of longer wavelength ''green-gap'' range LEDs where poor IQE and efficiency droop are more prominent due to high indium (In) in the active region. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Short Wavelength Electromagnetic Perturbations Excited Near the Solar Probe Plus Spacecraft in the Inner Heliosphere: 2.5D Hybrid Modeling

    Science.gov (United States)

    Lipatov, Alexander S.; Sittler, Edward C.; Hartle, Richard E.; Cooper, John F.

    2011-01-01

    A 2.5D numerical plasma model of the interaction of the solar wind (SW) with the Solar Probe Plus spacecraft (SPPSC) is presented. These results should be interpreted as a basic plasma model derived from the SW-interaction with the spacecraft (SC), which could have consequences for both plasma wave and electron plasma measurements on board the SC in the inner heliosphere. Compression waves and electric field jumps with amplitudes of about 1.5 V/m and (12-18) V/m were also observed. A strong polarization electric field was also observed in the wing of the plasma wake. However, 2.5D hybrid modeling did not show excitation of whistler/Alfven waves in the upstream connected with the bidirectional current closure that was observed in short-time 3D modeling SPPSC and near a tether in the ionosphere. The observed strong electromagnetic perturbations may be a crucial point in the electromagnetic measurements planned for the future Solar Probe Plus (SPP) mission. The results of modeling electromagnetic field perturbations in the SW due to shot noise in absence of SPPSC are also discussed.

  7. The range and effectiveness of short-term measures to reduce traffic emissions during high air pollution episodes

    International Nuclear Information System (INIS)

    Elsom, Derek M.

    1999-01-01

    Concern for continuing poor urban air quality, caused primarily by motor vehicles emissions, and the slow progress being made towards reducing total vehicle emissions by long-term measures, such as improving fuel and vehicle technologies, has prompted some authorities to try to reduce the severity and duration of high air pollution episodes by implementing short-term traffic restraint measures. This paper reviews the range of episodic air quality management schemes applied in cities around the world and comments on the effectiveness of such schemes. The difficulty of targeting vehicles according to the contribution they make to the air quality problem is highlighted. The problem of some schemes simply causing a displacement of the area of excessive vehicle emissions rather than reducing total emissions is reviewed. Rapid developments in telematics and improved urban air quality and traffic monitoring networks (e.g. Urban Traffic Management and Control systems) may offer significant improvements in the effectiveness of episodic management schemes in the future. (Author)

  8. Wavelength converter technology

    DEFF Research Database (Denmark)

    Kloch, Allan; Hansen, Peter Bukhave; Poulsen, Henrik Nørskov

    1999-01-01

    Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers.......Wavelength conversion is important since it ensures full flexibility of the WDM network layer. Progress in optical wavelength converter technology is reviewed with emphasis on all-optical wavelength converter types based on semiconductor optical amplifiers....

  9. Wavelength and coherence effects on the growth mechanism of silicon nanopillars and their use in the modification of spontaneous lifetime emission of BODIPY dye molecules

    Energy Technology Data Exchange (ETDEWEB)

    Acikgoz, Sabriye [Bogazici University, Department of Physics, Istanbul (Turkey); Karamanoglu Mehmetbey University, Department of Material Science and Engineering, Karaman (Turkey); Bilen, Bukem; Saygili, Asli C.; Aktas, Gulen; Inci, Mehmet Naci [Bogazici University, Department of Physics, Istanbul (Turkey); Sanyal, Amitav [Bogazici University, Department of Chemistry, Istanbul (Turkey)

    2012-09-15

    Silicon nanopillars are grown by an electrochemical anodization of p-type silicon wafers at low current densities in a hydrofluoric acid solution. CW, white light, and various UV pulsed lasers are employed as illumination sources in sample preparation to study wavelength and coherence effects on the growth mechanism of the nanopillars. Coherence is observed to be the foundation of regularity in obtaining conical shapes. The pillar size is found to be almost linearly proportional to the employed illumination wavelength during their growth. BODIPY dye molecules are chemically attached to these silicon nanopillars and the radiative decay rates are investigated by means of a time-resolved fluorescence experiment. The decay rate of the dye molecules embedded in the vicinity of various size pillar tips is significantly affected due to different apex angles of the conical nature. It is demonstrated that the pillar size and the separation between pillars can be adjusted if one uses a coherent light source with an appropriate wavelength during the course of fabrication process. Since change in the decay rate is due to tips of the pillars only, separation of a few micrometers between pillar tips allows one to directly monitor a dye, which is embedded to the tip of a single nanopillar, via a confocal microscopic method for the spontaneous lifetime measurements, without having needed to any extra efforts for an in situ imaging process. It is observed that as the pillar size gets smaller, the inhibition in the spontaneous lifetime of BODIPY is more pronounced. In addition, a more regular pillar structure yields nonvarying decay rates of the dye molecules throughout the silicon sample. (orig.)

  10. An improved quantum-behaved particle swarm optimization method for short-term combined economic emission hydrothermal scheduling

    Energy Technology Data Exchange (ETDEWEB)

    Lu, Songfeng; Sun, Chengfu; Lu, Zhengding [School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-03-15

    This paper presents a modified quantum-behaved particle swarm optimization (QPSO) for short-term combined economic emission scheduling (CEES) of hydrothermal power systems with several equality and inequality constraints. The hydrothermal scheduling is formulated as a bi-objective problem: (i) minimizing fuel cost and (ii) minimizing pollutant emission. The bi-objective problem is converted into a single objective one by price penalty factor. The proposed method, denoted as QPSO-DM, combines the QPSO algorithm with differential mutation operation to enhance the global search ability. In this study, heuristic strategies are proposed to handle the equality constraints especially water dynamic balance constraints and active power balance constraints. A feasibility-based selection technique is also employed to meet the reservoir storage volumes constraints. To show the efficiency of the proposed method, different case studies are carried out and QPSO-DM is compared with the differential evolution (DE), the particle swarm optimization (PSO) with same heuristic strategies in terms of the solution quality, robustness and convergence property. The simulation results show that the proposed method is capable of yielding higher-quality solutions stably and efficiently in the short-term hydrothermal scheduling than any other tested optimization algorithms. (author)

  11. An improved quantum-behaved particle swarm optimization method for short-term combined economic emission hydrothermal scheduling

    Energy Technology Data Exchange (ETDEWEB)

    Lu Songfeng [School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Sun Chengfu, E-mail: ajason_369@sina.co [School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China); Lu Zhengding [School of Computer Science and Technology, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2010-03-15

    This paper presents a modified quantum-behaved particle swarm optimization (QPSO) for short-term combined economic emission scheduling (CEES) of hydrothermal power systems with several equality and inequality constraints. The hydrothermal scheduling is formulated as a bi-objective problem: (i) minimizing fuel cost and (ii) minimizing pollutant emission. The bi-objective problem is converted into a single objective one by price penalty factor. The proposed method, denoted as QPSO-DM, combines the QPSO algorithm with differential mutation operation to enhance the global search ability. In this study, heuristic strategies are proposed to handle the equality constraints especially water dynamic balance constraints and active power balance constraints. A feasibility-based selection technique is also employed to meet the reservoir storage volumes constraints. To show the efficiency of the proposed method, different case studies are carried out and QPSO-DM is compared with the differential evolution (DE), the particle swarm optimization (PSO) with same heuristic strategies in terms of the solution quality, robustness and convergence property. The simulation results show that the proposed method is capable of yielding higher-quality solutions stably and efficiently in the short-term hydrothermal scheduling than any other tested optimization algorithms.

  12. An improved quantum-behaved particle swarm optimization method for short-term combined economic emission hydrothermal scheduling

    International Nuclear Information System (INIS)

    Lu Songfeng; Sun Chengfu; Lu Zhengding

    2010-01-01

    This paper presents a modified quantum-behaved particle swarm optimization (QPSO) for short-term combined economic emission scheduling (CEES) of hydrothermal power systems with several equality and inequality constraints. The hydrothermal scheduling is formulated as a bi-objective problem: (i) minimizing fuel cost and (ii) minimizing pollutant emission. The bi-objective problem is converted into a single objective one by price penalty factor. The proposed method, denoted as QPSO-DM, combines the QPSO algorithm with differential mutation operation to enhance the global search ability. In this study, heuristic strategies are proposed to handle the equality constraints especially water dynamic balance constraints and active power balance constraints. A feasibility-based selection technique is also employed to meet the reservoir storage volumes constraints. To show the efficiency of the proposed method, different case studies are carried out and QPSO-DM is compared with the differential evolution (DE), the particle swarm optimization (PSO) with same heuristic strategies in terms of the solution quality, robustness and convergence property. The simulation results show that the proposed method is capable of yielding higher-quality solutions stably and efficiently in the short-term hydrothermal scheduling than any other tested optimization algorithms.

  13. Greenhouse gas emission rate estimates from airborne remote sensing in the short-wave infrared

    Energy Technology Data Exchange (ETDEWEB)

    Krings, Thomas

    2013-01-30

    The quantification of emissions of the greenhouse gases carbon dioxide (CO{sub 2}) and methane (CH{sub 4}) is essential for attributing the roles of anthropogenic activity and natural phenomena in global climate change. The current measurement systems and networks, whilst having improved during the last decades, are deficient in many respects. For example, the emissions from localised and point sources such as fossil fuel exploration sites are not readily assessed. A tool developed to better understand point sources of CO{sub 2} and CH{sub 4} is the optical remote sensing instrument MAMAP, operated from aircraft. With a ground scene size of the order of 50m and a relative accuracy of the column-averaged dry air mole fractions of about 0.3% for XCO{sub 2} and less than 0.4% for XCH{sub 4}, MAMAP can make a significant contribution in this respect. Detailed sensitivity studies showed that the modified WFM-DOAS retrieval algorithm used for MAMAP has an approximate accuracy of about 0.24% for XCH{sub 4} and XCO{sub 2} in typical atmospheric conditions. At the example of CO{sub 2} plumes from two different power plants and CH{sub 4} plumes from coal mine ventilation shafts, two inversion approaches to obtain emission rates were developed and tested. One is based on an optimal estimation scheme to fit Gaussian plume models from multiple sources to the data and the other is based on a simple Gaussian integral method. Compared to CO{sub 2} emission estimates as reported by the power plants' operator within the framework of emission databases (24 and 13 MtCO{sub 2} yr{sup -1}), the results of the individual inversion techniques were within ±10% with uncertainties of ±20-30% mainly due to insufficient wind information and non-stationary atmospheric conditions. Measurements at the coal mine included on-site wind observations by an aircraft turbulence probe that could be utilised to calibrate the wind model. In this case, the inversion results have a bias of less than 1

  14. Impact of preindustrial to present-day changes in short-lived pollutant emissions on atmospheric composition and climate forcing

    Science.gov (United States)

    Naik, Vaishali; Horowitz, Larry W.; Fiore, Arlene M.; Ginoux, Paul; Mao, Jingqiu; Aghedo, Adetutu M.; Levy, Hiram

    2013-07-01

    We describe and evaluate atmospheric chemistry in the newly developed Geophysical Fluid Dynamics Laboratory chemistry-climate model (GFDL AM3) and apply it to investigate the net impact of preindustrial (PI) to present (PD) changes in short-lived pollutant emissions (ozone precursors, sulfur dioxide, and carbonaceous aerosols) and methane concentration on atmospheric composition and climate forcing. The inclusion of online troposphere-stratosphere interactions, gas-aerosol chemistry, and aerosol-cloud interactions (including direct and indirect aerosol radiative effects) in AM3 enables a more complete representation of interactions among short-lived species, and thus their net climate impact, than was considered in previous climate assessments. The base AM3 simulation, driven with observed sea surface temperature (SST) and sea ice cover (SIC) over the period 1981-2007, generally reproduces the observed mean magnitude, spatial distribution, and seasonal cycle of tropospheric ozone and carbon monoxide. The global mean aerosol optical depth in our base simulation is within 5% of satellite measurements over the 1982-2006 time period. We conduct a pair of simulations in which only the short-lived pollutant emissions and methane concentrations are changed from PI (1860) to PD (2000) levels (i.e., SST, SIC, greenhouse gases, and ozone-depleting substances are held at PD levels). From the PI to PD, we find that changes in short-lived pollutant emissions and methane have caused the tropospheric ozone burden to increase by 39% and the global burdens of sulfate, black carbon, and organic carbon to increase by factors of 3, 2.4, and 1.4, respectively. Tropospheric hydroxyl concentration decreases by 7%, showing that increases in OH sinks (methane, carbon monoxide, nonmethane volatile organic compounds, and sulfur dioxide) dominate over sources (ozone and nitrogen oxides) in the model. Combined changes in tropospheric ozone and aerosols cause a net negative top

  15. One-pot and ultrafast synthesis of nitrogen and phosphorus co-doped carbon dots possessing bright dual wavelength fluorescence emission

    Science.gov (United States)

    Sun, Xiangcheng; Brückner, Christian; Lei, Yu

    2015-10-01

    Very brief microwave heating of aniline, ethylene diamine, and phosphoric acid in water at ambient pressure generated nitrogen and phosphorus co-doped carbon dots (N,P-CDs) that exhibit bright dual blue (centred at 450 nm; 51% quantum yield) and green (centred at 510 nm, 38% quantum yield) fluorescence emission bands. The N,P-CDs were characterized using TEM, XRD, XPS, IR, UV-vis, and fluorescence spectroscopy, demonstrating their partially crystalline carbon, partially amorphous structures, and the incorporation of O, N, and P into the carbogenic scaffold. The N,P-CDs demonstrated excitation-dependent and nearly pH-independent emission properties. The unique dual emission properties lay the foundation for the use of N,P-CDs in ratiometric sensing applications.Very brief microwave heating of aniline, ethylene diamine, and phosphoric acid in water at ambient pressure generated nitrogen and phosphorus co-doped carbon dots (N,P-CDs) that exhibit bright dual blue (centred at 450 nm; 51% quantum yield) and green (centred at 510 nm, 38% quantum yield) fluorescence emission bands. The N,P-CDs were characterized using TEM, XRD, XPS, IR, UV-vis, and fluorescence spectroscopy, demonstrating their partially crystalline carbon, partially amorphous structures, and the incorporation of O, N, and P into the carbogenic scaffold. The N,P-CDs demonstrated excitation-dependent and nearly pH-independent emission properties. The unique dual emission properties lay the foundation for the use of N,P-CDs in ratiometric sensing applications. Electronic supplementary information (ESI) available: Detailed experimental section, XRD, FTIR, explosive sensing and the applications results. See DOI: 10.1039/c5nr05549k

  16. Long- and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano, Lanzarote, Canary Islands

    Science.gov (United States)

    Hernández, P. A.; Padilla, G.; Calvo, D.; Padrón, E.; Melian, G.; Dionis, S.; Nolasco, D.; Barrancos, J.; Rodríguez, F.; Pérez, N.

    2012-04-01

    Lanzarote Island is an emergent part of the East Canary Ridge and it is situated approximately 100 km from the NW coast of Morocco, covering an area of about 795km2. The largest historical eruption of the Canary Islands, Timanfaya, took place during 1730-36 in this island when long-term eruptions from a NE-SW-trending fissure formed the Montañas del Fuego. The last eruption at Lanzarote Island occurred during 1824, Tinguaton volcano, and produced a much smaller lava flow that reached the SW coast. At present, one of the most prominent phenomena at Timanfaya volcanic field is the high maintained superficial temperatures occurring in the area since the 1730 volcanic eruption. The maximum temperatures recorded in this zone are 605°C, taken in a slightly inclined well 13 m deep. Since fumarolic activity is absent at the surface environment of Lanzarote, to study the diffuse CO2 emission becomes an ideal geochemical tool for monitoring its volcanic activity. Soil CO2 efflux surveys were conducted throughout Timanfaya volcanic field and surrounding areas during the summer periods of 2006, 2007, 2008, 2009, fall period of 2010 and winter, spring and summer periods of 2011 to investigate long and short-term temporal variations of the diffuse CO2 emission from Timanfaya volcano. Soil CO2 efflux surveys were undertaken at Timanfaya volcanic field always under stable weather conditions to minimize effects of meteorological conditions on the CO2 at the soil atmosphere. Approximately 370-430 sampling sites were selected at the surface environment of Timanfaya to obtain an even distribution of the sampling points over the study area. The accumulation chamber method (Parkinson et al., 1981) was used to perform soil CO2 efflux measurements in-situ by means of a portable non dispersive infrared (NDIR) CO2 analyzer, which was interfaced to a hand size computer that runs data acquisition software. At each sampling site, soil temperature at 15 and 40cm depth was also measured by

  17. Survey of exposure of physiotherapist operators to emissions from microwave and short wave diathermy equipment

    International Nuclear Information System (INIS)

    Coppell, R.B.

    1987-01-01

    An extensive survey of levels of electromagnetic fields in the vicinity of microwave and short wave diathermy equipment is presented and occupational exposure of physiotherapist operators is assessed. There was a good response to mailed questionnaires to 18 hospital boards, 21 private hospitals, and 148 private physiotherapy practices in Christchruch and centres of the north island of New Zealand. Within 34 public hospitals and 57 private practice of those so contacted, who also volunteered to participate, measurements were made in numerous positions about operating equipment. For practical reasons, manufactured phantom sections were substituted for real patients. Levels of microwave power flux density were found to vary according to position and to orientation of equipment and patient phantom. Provided, microwave diathermy equipment is used with reasonable care, excessive exposure of the physiotherapist operator is considered very unlikely. Levels of electric and magnetic field strength squared in the vicinity of simulated body sections under short wave diathermy treatment were found to be highly localised and strongly dependent upon the type of applicator used and the proximity of connecting leads. Operating procedures, including distances of separation, are recommended to protect operators from excessive exposure. (author). 30 refs., 8 tabs., 4 figs., ills

  18. Short-Wavelength Countermeasures for Circadian Desynchrony

    National Research Council Canada - National Science Library

    Heller, H. C; Smith, Mark

    2008-01-01

    .... Exposure of humans to bright light for an hour or more at the right phase of the circadian cycle produces significant phase shifts of circadian rhythms speeding recovery from jet-lag, and optimizing...

  19. Physics of short-wavelength-laser design

    Energy Technology Data Exchange (ETDEWEB)

    Hagelstein, P.L.

    1981-01-01

    The physics and design of vuv and soft x-ray lasers pumped by ICF class high intensity infrared laser drivers are described (for example, the SHIVA laser facility at LLNL). Laser design and physics issues are discussed in the case of a photoionization pumping scheme involving Ne II and line pumping schemes involving H-like and He-like neon.

  20. Demonstration of a Short Wavelength Chemical Laser

    National Research Council Canada - National Science Library

    Gole, James

    1999-01-01

    ...)). Using this gain medium in a full vacuum cavity constructed following the design of the HF overtone system at the University of Illinois, Urbana, we have pursued and are continuing experiments...

  1. Short-Wavelength Countermeasures for Circadian Desynchrony

    National Research Council Canada - National Science Library

    Heller, H. C; Smith, Mark

    2008-01-01

    ... cognitive functionality and restorative sleep. Our work on mice produced the unexpected result that exposure to intermittent millisecond flashes of light distributed over an hour for a total of only 120 msec...

  2. Artificial light pollution: Shifting spectral wavelengths to mitigate physiological and health consequences in a nocturnal marsupial mammal.

    Science.gov (United States)

    Dimovski, Alicia M; Robert, Kylie A

    2018-05-02

    The focus of sustainable lighting tends to be on reduced CO 2 emissions and cost savings, but not on the wider environmental effects. Ironically, the introduction of energy-efficient lighting, such as light emitting diodes (LEDs), may be having a great impact on the health of wildlife. These white LEDs are generated with a high content of short-wavelength 'blue' light. While light of any kind can suppress melatonin and the physiological processes it regulates, these short wavelengths are potent suppressors of melatonin. Here, we manipulated the spectral composition of LED lights and tested their capacity to mitigate the physiological and health consequences associated with their use. We experimentally investigated the impact of white LEDs (peak wavelength 448 nm; mean irradiance 2.87 W/m 2 ), long-wavelength shifted amber LEDs (peak wavelength 605 nm; mean irradiance 2.00 W/m 2 ), and no lighting (irradiance from sky glow light treatments. White LED exposed wallabies had significantly suppressed nocturnal melatonin compared to no light and amber LED exposed wallabies, while there was no difference in lipid peroxidation. Antioxidant capacity declined from baseline to week 10 under all treatments. These results provide further evidence that short-wavelength light at night is a potent suppressor of nocturnal melatonin. Importantly, we also illustrate that shifting the spectral output to longer wavelengths could mitigate these negative physiological impacts. © 2018 Wiley Periodicals, Inc.

  3. Analysis of the fluctuation-induced excess dc conductivity of epitaxial YBa2Cu3O7 films: Influence of a short-wavelength cutoff in the fluctuation spectrum

    International Nuclear Information System (INIS)

    Hopfengaertner, R.; Hensel, B.; Saemann-Ischenko, G.

    1991-01-01

    Measurements of the temperature dependence of the in-plane dc conductivity on various high-quality epitaxial YBa 2 Cu 3 O 7 films are presented. The rounding of the resistivity in the transition region has been analyzed in terms of the anisotropic Aslamazov-Larkin (AL), Lawrence-Doniach (LD), and Maki-Thompson theories. In the framework of the time-dependent Ginzburg-Landau (GL) approach we have investigated the influence of a short-wavelength cutoff parameter in the fluctuation spectrum of the AL and LD term. In both theories this physically reasonable cutoff leads to a considerable reduction of the predicted excess dc conductivity at higher temperatures. Moreover, the three-dimensional anisotropic AL term, taking the cutoff into account, predicts nearly the same excess conductivity as the original LD term, although these two approaches describe different systems. A good agreement between experimental data and LD as well as the modified three-dimensional anisotropic AL term was found in the region 1.01T c ≤T≤1.1T c . The zero-temperature GL coherence length ξ c (0) has been estimated to be about 1.5 A

  4. Magnetar Central Engine and Possible Gravitational Wave Emission of Nearby Short GRB 160821B

    Energy Technology Data Exchange (ETDEWEB)

    Lü, Hou-Jun; Zhang, Hai-Ming; Zhong, Shu-Qing; Liang, En-Wei [GXU-NAOC Center for Astrophysics and Space Sciences, Department of Physics, Guangxi University, Nanning 530004 (China); Hou, Shu-Jin [College of Physics and Electronic Engineering, Nanyang Normal University, Nanyang, Henan 473061 (China); Sun, Hui [Department of Astronomy, School of Physics, Peking University, Beijing 100871 (China); Rice, Jared, E-mail: lhj@gxu.edu.edu [Department of Physics and Astronomy, University of Nevada Las Vegas, NV 89154 (United States)

    2017-02-01

    GRB 160821B is a short gamma-ray burst (SGRB) at redshift z = 0.16, with a duration less than 1 s and without any “extended emission” detected up to more than 100 s in both Swift /BAT and Fermi /GBM bands. An X-ray plateau with a sharp drop 180 s after the BAT trigger was observed with Swift /XRT. No supernova or kilo-nova signature was detected. Assuming the central engine of this SGRB is a recently born supra-massive magnetar, we can explain the SGRB as jet radiation and its X-ray plateau as the internal energy dissipation of the pulsar wind as it spins down. We constrain its surface magnetic field to B {sub p} < 3.12 × 10{sup 16} G and initial spin period to P{sub 0} < 8.5 × 10{sup −3} s. Its equation of state is consistent with the GM1 model with M{sub TOV} ∼ 2.37 M {sub ⊙} and ellipticity ϵ < 0.07. Its gravitational wave (GW) radiation may be detectable with the future Einstein Telescope, but is much weaker than the current detectability limit of Advanced LIGO. The GW radiation of such an event would be detectable by Advanced LIGO if it occurred at a distance of 100 Mpc ( z = 0.023).

  5. Enhancing carrier injection in the active region of a 280nm emission wavelength LED using graded hole and electron blocking layers

    KAUST Repository

    Janjua, Bilal

    2014-02-27

    A theoretical investigation of AlGaN UV-LED with band engineering of hole and electron blocking layers (HBL and EBL, respectively) was conducted with an aim to improve injection efficiency and reduce efficiency droop in the UV LEDs. The analysis is based on energy band diagrams, carrier distribution and recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates) in the quantum well, under equilibrium and forward bias conditions. Electron blocking layer is based on AlaGa1-aN / Al b → cGa1-b → 1-cN / AldGa 1-dN, where a < d < b < c. A graded layer sandwiched between large bandgap AlGaN materials was found to be effective in simultaneously blocking electrons and providing polarization field enhanced carrier injection. The graded interlayer reduces polarization induced band bending and mitigates the related drawback of impediment of holes injection. Similarly on the n-side, the Alx → yGa1-x → 1-yN / AlzGa 1-zN (x < z < y) barrier acts as a hole blocking layer. The reduced carrier leakage and enhanced carrier density in the active region results in significant improvement in radiative recombination rate compared to a structure with the conventional rectangular EBL layers. The improvement in device performance comes from meticulously designing the hole and electron blocking layers to increase carrier injection efficiency. The quantum well based UV-LED was designed to emit at 280nm, which is an effective wavelength for water disinfection application.

  6. Enhancing carrier injection in the active region of a 280nm emission wavelength LED using graded hole and electron blocking layers

    KAUST Repository

    Janjua, Bilal; Ng, Tien Khee; Alyamani, Ahmed Y.; El-Desouki, Munir M.; Ooi, Boon S.

    2014-01-01

    A theoretical investigation of AlGaN UV-LED with band engineering of hole and electron blocking layers (HBL and EBL, respectively) was conducted with an aim to improve injection efficiency and reduce efficiency droop in the UV LEDs. The analysis is based on energy band diagrams, carrier distribution and recombination rates (Shockley-Reed-Hall, Auger, and radiative recombination rates) in the quantum well, under equilibrium and forward bias conditions. Electron blocking layer is based on AlaGa1-aN / Al b → cGa1-b → 1-cN / AldGa 1-dN, where a < d < b < c. A graded layer sandwiched between large bandgap AlGaN materials was found to be effective in simultaneously blocking electrons and providing polarization field enhanced carrier injection. The graded interlayer reduces polarization induced band bending and mitigates the related drawback of impediment of holes injection. Similarly on the n-side, the Alx → yGa1-x → 1-yN / AlzGa 1-zN (x < z < y) barrier acts as a hole blocking layer. The reduced carrier leakage and enhanced carrier density in the active region results in significant improvement in radiative recombination rate compared to a structure with the conventional rectangular EBL layers. The improvement in device performance comes from meticulously designing the hole and electron blocking layers to increase carrier injection efficiency. The quantum well based UV-LED was designed to emit at 280nm, which is an effective wavelength for water disinfection application.

  7. Emission Characteristics of Laser-Induced Plasma Using Collinear Long and Short Dual-Pulse Laser-Induced Breakdown Spectroscopy (LIBS).

    Science.gov (United States)

    Wang, Zhenzhen; Deguchi, Yoshihiro; Liu, Renwei; Ikutomo, Akihiro; Zhang, Zhenzhen; Chong, Daotong; Yan, Junjie; Liu, Jiping; Shiou, Fang-Jung

    2017-09-01

    Collinear long and short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) was employed to clarify the emission characteristics from laser-induced plasma. The plasma was sustained and became stable by the long pulse-width laser with the pulse width of 60 μs under free running (FR) conditions as an external energy source. Comparing the measurement results of stainless steel in air using single-pulse LIBS (SP-LIBS) and DP-LIBS, the emission intensity was markedly enhanced using DP-LIBS. The temperature of plasma induced by DP-LIBS was maintained at a higher temperature under different gate delay time and short pulse-width laser power conditions compared with those measured using short SP-LIBS. Moreover, the variation rates of plasma temperatures measured using DP-LIBS were also lower. The superior detection ability was verified by the measurement of aluminum sample in water. The spectra were clearly detected using DP-LIBS, whereas it cannot be identified using SP-LIBS of short and long pulse widths. The effects of gate delay time and short pulse-width laser power were also discussed. These results demonstrate the feasibility and enhanced detection ability of the proposed collinear long and short DP-LIBS method.

  8. Wavelength conversion devices

    DEFF Research Database (Denmark)

    Mikkelsen, Benny; Durhuus, Terji; Jørgensen, Carsten

    1996-01-01

    system requirements. The ideal wavelength converter should be transparent to the bit rate and signal format and provide an unchirped output signal with both a high extinction ratio and a large signal-to-noise ratio. It should allow conversion to both shorter and longer wavelengths with equal performance...

  9. Functional characterization of spectral tuning mechanisms in the great bowerbird short-wavelength sensitive visual pigment (SWS1), and the origins of UV/violet vision in passerines and parrots.

    Science.gov (United States)

    van Hazel, Ilke; Sabouhanian, Amir; Day, Lainy; Endler, John A; Chang, Belinda S W

    2013-11-13

    One of the most striking features of avian vision is the variation in spectral sensitivity of the short wavelength sensitive (SWS1) opsins, which can be divided into two sub-types: violet- and UV- sensitive (VS & UVS). In birds, UVS has been found in both passerines and parrots, groups that were recently shown to be sister orders. While all parrots are thought to be UVS, recent evidence suggests some passerine lineages may also be VS. The great bowerbird (Chlamydera nuchalis) is a passerine notable for its courtship behaviours in which males build and decorate elaborate bower structures. The great bowerbird SWS1 sequence possesses an unusual residue combination at known spectral tuning sites that has not been previously investigated in mutagenesis experiments. In this study, the SWS1 opsin of C. nuchalis was expressed along with a series of spectral tuning mutants and ancestral passerine SWS1 pigments, allowing us to investigate spectral tuning mechanisms and explore the evolution of UV/violet sensitivity in early passerines and parrots. The expressed C. nuchalis SWS1 opsin was found to be a VS pigment, with a λmax of 403 nm. Bowerbird SWS1 mutants C86F, S90C, and C86S/S90C all shifted λmax into the UV, whereas C86S had no effect. Experimentally recreated ancestral passerine and parrot/passerine SWS1 pigments were both found to be VS, indicating that UV sensitivity evolved independently in passerines and parrots from a VS ancestor. Our mutagenesis studies indicate that spectral tuning in C. nuchalis is mediated by mechanisms similar to those of other birds. Interestingly, our ancestral sequence reconstructions of SWS1 in landbird evolution suggest multiple transitions from VS to UVS, but no instances of the reverse. Our results not only provide a more precise prediction of where these spectral sensitivity shifts occurred, but also confirm the hypothesis that birds are an unusual exception among vertebrates where some descendants re-evolved UVS from a violet type

  10. Influence of blue light spectrum filter on short-wavelength and standard automated perimetries Influência de filtro para o espectro azul da luz na perimetria computadorizada branco-branco e azul-amarelo

    Directory of Open Access Journals (Sweden)

    Leonardo Cunha Castro

    2006-10-01

    Full Text Available PURPOSE: To evaluate the influence of a blue light spectrum filter (BLSF, similar in light spectrum transmittance to the intraocular lens Acrysof NaturalTM, on standard automated perimetry (SAP and short-wavelength automated perimetry (SWAP. METHODS: Twenty young individuals (OBJETIVO: Avaliar a influência de um filtro para o espectro azul da luz, semelhante à lente intra-ocular Acrysof Natural®, nos exames de perimetria automatizada padrão (branco-no-branco e de comprimento de onda curto (azul-no-amarelo. MÉTODOS: Vinte pacientes jovens sem alterações oculares (20 olhos realizaram seqüência de 4 exames de campo visual: perimetria automatizada padrão e azul-no-amarelo com e sem o filtro para o espectro azul da luz. Os índices de limiar foveal (FT, desvio médio (MD e desvio-padrão (PSD obtidos em todos os exames e a diferença causada pela excentricidade nos exames de perimetria automatizada azul-no-amarelo foram analisados. Variabilidade interindivíduos (desvio-padrão dos pontos testados foi calculada. RESULTADOS: Observou-se redução estatisticamente significante no desvio médio (p<0.001 e no limiar foveal (p<0.001 medidos pela perimetria automatizada azul-no-amarelo com o uso do filtro para o espectro azul da luz comparado quando realizado sem o filtro. Nenhum outro índice avaliado apresentou diferença estatisticamente significante nos exames de perimetria automatizada padrão ou azul-no-amarelo. Foi notado aumento da variabilidade interindivíduos com a excentricidade nos exames de perimetria automatizada azul-no-amarelo com e sem o uso do filtro para o espectro azul da luz, assim como a diferença de sensibilidade entre os hemisférios inferior e superior (hemisfério inferior menos superior, mas não houve diferença estatisticamente significante quando comparados os exames com e sem o uso do filtro. Quando foram comparados os 4 pontos mais inferiores e os 4 pontos mais superiores, a diferença inferior-superior aumentou

  11. Cover crop rotations in no-till system: short-term CO2 emissions and soybean yield

    Directory of Open Access Journals (Sweden)

    João Paulo Gonsiorkiewicz Rigon

    Full Text Available ABSTRACT: In addition to improving sustainability in cropping systems, the use of a spring and winter crop rotation system may be a viable option for mitigating soil CO2 emissions (ECO2. This study aimed to determine short-term ECO2 as affected by crop rotations and soil management over one soybean cycle in two no-till experiments, and to assess the soybean yields with the lowest ECO2. Two experiments were carried out in fall-winter as follows: i triticale and sunflower were grown in Typic Rhodudalf (TR, and ii ruzigrass, grain sorghum, and ruzigrass + grain sorghum were grown in Rhodic Hapludox (RH. In the spring, pearl millet, sunn hemp, and forage sorghum were grown in both experiments. In addition, in TR a fallow treatment was also applied in the spring. Soybean was grown every year in the summer, and ECO2 were recorded during the growing period. The average ECO2 was 0.58 and 0.84 g m2 h–1 with accumulated ECO2 of 5,268 and 7,813 kg ha–1 C-CO2 in TR and RH, respectively. Sunn hemp, when compared to pearl millet, resulted in lower ECO2 by up to 12 % and an increase in soybean yield of 9% in TR. In RH, under the winter crop Ruzigrazz+Sorghum, ECO2 were lower by 17%, although with the same soybean yield. Soil moisture and N content of crop residues are the main drivers of ECO2 and soil clay content seems to play an important role in ECO2 that is worthy of further studies. In conclusion, sunn hemp in crop rotation may be utilized to mitigate ECO2 and improve soybean yield.

  12. CONFIRMING THE PRIMARILY SMOOTH STRUCTURE OF THE VEGA DEBRIS DISK AT MILLIMETER WAVELENGTHS

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, A. Meredith; Plambeck, Richard; Chiang, Eugene [Department of Astronomy, University of California, Berkeley, CA 94720 (United States); Wilner, David J.; Andrews, Sean M. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Mason, Brian [National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903-2475 (United States); Carpenter, John M. [California Institute of Technology, Department of Astronomy, MC 105-24, Pasadena, CA 91125 (United States); Chiang, Hsin-Fang [Institute for Astronomy, University of Hawaii, 640 North Aohoku Place, Hilo, HI 96720 (United States); Williams, Jonathan P. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Hales, Antonio [Joint ALMA Observatory, Av. El Golf 40, Piso 18, Santiago (Chile); Su, Kate [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Dicker, Simon; Korngut, Phil; Devlin, Mark, E-mail: mhughes@astro.berkeley.edu [Department of Physics and Astronomy, University of Pennsylvania, 209 South 33rd Street, Philadelphia, PA 19104 (United States)

    2012-05-01

    Clumpy structure in the debris disk around Vega has been previously reported at millimeter wavelengths and attributed to concentrations of dust grains trapped in resonances with an unseen planet. However, recent imaging at similar wavelengths with higher sensitivity has disputed the observed structure. We present three new millimeter-wavelength observations that help to resolve the puzzling and contradictory observations. We have observed the Vega system with the Submillimeter Array (SMA) at a wavelength of 880 {mu}m and an angular resolution of 5''; with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at a wavelength of 1.3 mm and an angular resolution of 5''; and with the Green Bank Telescope (GBT) at a wavelength of 3.3 mm and angular resolution of 10''. Despite high sensitivity and short baselines, we do not detect the Vega debris disk in either of the interferometric data sets (SMA and CARMA), which should be sensitive at high significance to clumpy structure based on previously reported observations. We obtain a marginal (3{sigma}) detection of disk emission in the GBT data; the spatial distribution of the emission is not well constrained. We analyze the observations in the context of several different models, demonstrating that the observations are consistent with a smooth, broad, axisymmetric disk with inner radius 20-100 AU and width {approx}> 50 AU. The interferometric data require that at least half of the 860 {mu}m emission detected by previous single-dish observations with the James Clerk Maxwell Telescope be distributed axisymmetrically, ruling out strong contributions from flux concentrations on spatial scales of {approx}<100 AU. These observations support recent results from the Plateau de Bure Interferometer indicating that previous detections of clumpy structure in the Vega debris disk were spurious.

  13. CONFIRMING THE PRIMARILY SMOOTH STRUCTURE OF THE VEGA DEBRIS DISK AT MILLIMETER WAVELENGTHS

    International Nuclear Information System (INIS)

    Hughes, A. Meredith; Plambeck, Richard; Chiang, Eugene; Wilner, David J.; Andrews, Sean M.; Mason, Brian; Carpenter, John M.; Chiang, Hsin-Fang; Williams, Jonathan P.; Hales, Antonio; Su, Kate; Dicker, Simon; Korngut, Phil; Devlin, Mark

    2012-01-01

    Clumpy structure in the debris disk around Vega has been previously reported at millimeter wavelengths and attributed to concentrations of dust grains trapped in resonances with an unseen planet. However, recent imaging at similar wavelengths with higher sensitivity has disputed the observed structure. We present three new millimeter-wavelength observations that help to resolve the puzzling and contradictory observations. We have observed the Vega system with the Submillimeter Array (SMA) at a wavelength of 880 μm and an angular resolution of 5''; with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at a wavelength of 1.3 mm and an angular resolution of 5''; and with the Green Bank Telescope (GBT) at a wavelength of 3.3 mm and angular resolution of 10''. Despite high sensitivity and short baselines, we do not detect the Vega debris disk in either of the interferometric data sets (SMA and CARMA), which should be sensitive at high significance to clumpy structure based on previously reported observations. We obtain a marginal (3σ) detection of disk emission in the GBT data; the spatial distribution of the emission is not well constrained. We analyze the observations in the context of several different models, demonstrating that the observations are consistent with a smooth, broad, axisymmetric disk with inner radius 20-100 AU and width ∼> 50 AU. The interferometric data require that at least half of the 860 μm emission detected by previous single-dish observations with the James Clerk Maxwell Telescope be distributed axisymmetrically, ruling out strong contributions from flux concentrations on spatial scales of ∼<100 AU. These observations support recent results from the Plateau de Bure Interferometer indicating that previous detections of clumpy structure in the Vega debris disk were spurious.

  14. Short-term nitrous oxide profile dynamics and emissions response to water, nitrogen and carbon additions in two tropical soils

    Science.gov (United States)

    A. D. Nobre; M. Keller; P. M. Crill; R. C. Harriss

    2001-01-01

    Tropical soils are potentially the highest and least studied nitrous oxide (N2O) production areas in the world. The effect of water, nitrate and glucose additions on profile concentrations and episodic emissions of N2O for two volcanic soils in Costa Rica was examined. Magnitudes of episodic N2O pulses, as well as overall N2O emissions, varied considerably and...

  15. Influence of Metal Transfer Stability and Shielding Gas Composition on CO and CO2 Emissions during Short-circuiting MIG/MAG Welding

    Directory of Open Access Journals (Sweden)

    Valter Alves de Meneses

    Full Text Available Abstract: Several studies have demonstrated the influence of parameters and shielding gas on metal transfer stability or on the generation of fumes in MIG/MAG welding, but little or nothing has been discussed regarding the emission of toxic and asphyxiating gases, particularly as it pertains to parameterization of the process. The purpose of this study was to analyze and evaluate the effect of manufacturing aspects of welding processes (short-circuit metal transfer stability and shielding gas composition on the gas emission levels during MIG/MAG welding (occupational health and environmental aspects. Using mixtures of Argon with CO2 and O2 and maintaining the same average current and the same weld bead volume, short-circuit welding was performed with carbon steel welding wire in open (welder’s breathing zone and confined environments. The welding voltage was adjusted to gradually vary the transfer stability. It was found that the richer the composition of the shielding gas is in CO2, the more CO and CO2 are generated by the arc. However, unlike fume emission, voltage and transfer stability had no effect on the generation of these gases. It was also found that despite the large quantity of CO and CO2 emitted by the arc, especially when using pure CO2 shielding gas, there was no high level residual concentration of CO and CO2 in or near the worker’s breathing zone, even in confined work cells.

  16. Wavelength conversion technology

    DEFF Research Database (Denmark)

    Stubkjær, Kristian

    1998-01-01

    Optical wavelength conversion is currently attracting much interest. This is because it enables full flexibility and eases management of WDM fibre networks. The tutorial will review existing and potential application areas. Examples of node architectures and network demonstrators that use wavelen...

  17. Long wavelength scintillators for fiber-optic applications

    International Nuclear Information System (INIS)

    Lyons, P.B.; Franks, L.; Lutz, S.; Flournoy, J.; Fullman, E.

    1980-01-01

    The use of fiber optics in plasma diagnostics has spurred the development of long wavelength scintillators with fast temporal characteristics. In this paper we describe several new liquid scintillator systems with fluorescent emissions maxima up to 730 nm. Subnanosecond scintillator FWHM response times have been obtained by the operation of liquid scintillators at elevated temperatures. Data on fiber system sensitivity versus fiber length and scintillator emission wavelength will be presented

  18. Wavelength-stepped, actively mode-locked fiber laser based on wavelength-division-multiplexed optical delay lines

    Science.gov (United States)

    Lee, Eunjoo; Kim, Byoung Yoon

    2017-12-01

    We propose a new scheme for an actively mode-locked wavelength-swept fiber laser that produces a train of discretely wavelength-stepped pulses from a short fiber cavity. Pulses with different wavelengths are split and combined by standard wavelength division multiplexers with fiber delay lines. As a proof of concept, we demonstrate a laser using an erbium doped fiber amplifier and commercially available wavelength-division multiplexers with wavelength spacing of 0.8 nm. The results show simultaneous mode-locking at three different wavelengths. Laser output parameters in time domain, optical and radio frequency spectral domain, and the noise characteristics are presented. Suggestions for the improved design are discussed.

  19. Solar Observations at Submillimeter Wavelengths

    Science.gov (United States)

    Kaufmann, P.

    We review earlier to recent observational evidences and theoretical motivations leading to a renewed interest to observe flares in the submillimeter (submm) - infrared (IR) range of wavelengths. We describe the new solar dedicated submillimeter wave telescope which began operations at El Leoncito in the Argentina Andes: the SST project. It consists of focal plane arrays of two 405 GHz and four 212 GHz radiometers placed in a 1.5-m radome-enclosed Cassegrain antenna, operating simultaneously with one millisecond time resolution. The first solar events analyzed exhibited the onset of rapid submm-wave spikes (100-300 ms), well associated to other flare manifestations, especially at X-rays. The spikes positions were found scattered over the flaring source by tens of arcseconds. For one event an excellent association was found between the gamma-ray emission time profile and the rate of occurrence of submm-wave rapid spikes. The preliminary results favour the idea that bulk burst emissions are a response to numerous fast energetic injections, discrete in time, produced at different spatial positions over the flaring region. Coronal mass ejections were associated to the events studied. Their trajectories extrapolated to the solar surface appear to correspond to the onset time of the submm-wave spikes, which might represent an early signature of the CME's initial acceleration process.

  20. Wavelength sweepable laser source

    DEFF Research Database (Denmark)

    2014-01-01

    Wavelength sweepable laser source is disclosed, wherein the laser source is a semiconductor laser source adapted for generating laser light at a lasing wavelength. The laser source comprises a substrate, a first reflector, and a second reflector. The first and second reflector together defines...... and having a rest position, the second reflector and suspension together defining a microelectromechanical MEMS oscillator. The MEMS oscillator has a resonance frequency and is adapted for oscillating the second reflector on either side of the rest position.; The laser source further comprises electrical...... connections adapted for applying an electric field to the MEMS oscillator. Furthermore, a laser source system and a method of use of the laser source are disclosed....

  1. UV emission properties of thulium-doped fluorozirconate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Piramidowicz, R., E-mail: r.piramidowicz@elka.pw.edu.p [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland); Telekomunikacja Polska Research and Development Centre, Obrzezna 7, 02-691 Warsaw (Poland); Bok, A.; Klimczak, M.; Malinowski, M. [Institute of Microelectronics and Optoelectronics, Koszykowa 75, 00-662 Warsaw (Poland)

    2009-12-15

    In this work, we present our latest results on UV emission in bulk ZBLAN glasses doped with thulium ions, broadening knowledge of the short-wavelength optical properties of this system. We examined a set of samples with different activator concentrations (2500, 10,000, 25,000 and 50,000 ppm) in respect of absorption and short-wavelength emission properties. The concentration-dependant spectra of UV emission from the {sup 1}I{sub 6}+{sup 3}P{sub 0} and {sup 1}D{sub 2} levels and fluorescence dynamics profiles have been recorded and carefully examined under direct (one-photon) excitation, enabling discussion of fluorescence quenching mechanisms and determination of appropriate cross-relaxation rates. According to authors' best knowledge, the three-photon red-to-UV up-conversion has been reported for the first time under excitation of a laser diode.

  2. Short- and Long-Timescale Thermospheric Variability as Observed from OI 630.0 nm Dayglow Emissions from Low Latitudes

    Science.gov (United States)

    Pallamraju, Duggirala; Das, Uma; Chakrabarti, Supriya

    2011-01-01

    We carried out high-cadence (5 min) and high-spatial resolution (2deg magnetic latitude) observations of daytime OI 630.0 nm airglow emission brightness from a low-latitude station to understand the behavior of neutral dynamics in the daytime. The results indicate that the wave periodicities of 12.20 min, and 2 h exist over a wide spatial range of around 8deg-12deg magnetic latitudes. The 20.80 min periodicities in the dayglow seem to appear more often in the measurements closer to the magnetic equator and not at latitudes farther away. Further, periodicities in that range are found to be frequent in the variations of the equatorial electrojet (EEJ) strength as well. We show that wave periodicities due to the neutral dynamics, at least until around 8deg magnetic latitude, are influenced by those that affect the EEJ strength variation as well. Furthermore, the average daily OI 630.0 nm emission brightness over 3 months varied in consonance with that of the sunspot numbers indicating a strong solar influence on the magnitudes of dayglow emissions.

  3. Anisotropic and correlated emissions of short range charged particles in anti pAg/Br reactions at 1. 4 GeV/c incident momentum observed in photographic emulsions

    Energy Technology Data Exchange (ETDEWEB)

    Breivik, F.O.; Jacobsen, T.; Soerensen, S.O.

    1984-07-01

    Anti pAg/Br reactions at 1.4 GeV/c incident momentum are studied by means of the emulsion technique. A group of short range charged particles is observed. For the events with one short track, a backward and transversal emission is seen, which probably is due to some very fast process. For the events with two short tracks, a back-to-back emission is seen, indicating some two-body decay, where the target nucleus possibly behaves spectator-like.

  4. Anisotropic and correlated emissions of short range charged particles in anti pAg/Br reactions at 1.4 GeV/c incident momentum observed in photographic emulsions

    International Nuclear Information System (INIS)

    Breivik, F.O.; Jacobsen, T.; Soerensen, S.O.

    1984-01-01

    Anti pAg/Br reactions at 1.4 GeV/c incident momentum are studied by means of the emulsion technique. A group of short range charged particles is observed. For the events with one short track, a backward and transversal emission is seen, which probably is due to some very fast process. For the events with two short tracks, a back-to-back emission is seen, indicating some two-body decay, where the target nucleus possibly behaves spectator-like. (Auth.)

  5. Anisotropic and correlated emissions of short range charged particles in anti pAg/Br reactions of 1.4 GeV/c incident momentum observed in photographic emulsions

    International Nuclear Information System (INIS)

    Breivik, F.O.; Jacobsen, T.; Soerensen, S.O.

    1983-12-01

    Anti pAg/Br reactions at 1.4 GeV/c incident momentum were studied by means of the emulsion technique. A group of short range charged particles was observed. For the events with one short track, a backward and transversal emission was seen, probably due to some very fast process. For the events with two short tracks, a back-to-back emission was seen, indicating some two-body decay where the target nucleus possibly behaves spectator-like. The rates and forward collimations suggest that the same physical process causes the different multiplicities

  6. Short Communication: Emission of Oxygenated Polycyclic Aromatic Hydrocarbons from Biomass Pellet Burning in a Modern Burner for Cooking in China.

    Science.gov (United States)

    Shen, Guofeng; Wei, Siye; Zhang, Yanyan; Wang, Rong; Wang, Bin; Li, Wei; Shen, Huizhong; Huang, Ye; Chen, Yuanchen; Chen, Han; Wei, Wen; Tao, Shu

    2012-12-01

    Biomass pellets are undergoing fast deployment widely in the world, including China. To this stage, there were limited studies on the emissions of various organic pollutants from the burning of those pellets. In addition to parent polycyclic aromatic hydrocarbons, oxygenated PAHs (oPAHs) have been received increased concerns. In this study, emission factors of oPAHs (EF oPAHs ) were measured for two types of pellets made from corn straw and pine wood, respectively. Two combustion modes with (mode II) and without (mode I) secondary side air supply in a modern pellet burner were investigated. For the purpose of comparison, EF oPAHs for raw fuels combusted in a traditional cooking stove were also measured. EF oPAHs were 348±305 and 396±387 µg/kg in the combustion mode II for pine wood and corn straw pellets, respectively. In mode I, measured EF oPAHs were 77.7±49.4 and 189±118 µg/kg, respectively. EFs in mode II were higher (2-5 times) than those in mode I mainly due to the decreased combustion temperature under more excess air. Compared to EF oPAHs for raw corn straw and pine wood burned in a traditional cooking stove, total EF oPAHs for the pellets in mode I were significantly lower ( p < 0.05 ), likely due to increased combustion efficiencies and change in fuel properties. However, the difference between raw biomass fuels and the pellets burned in mode II was not statistically significant. Taking both the increased thermal efficiencies and decreased EFs into consideration, substantial reduction in oPAH emission can be expected if the biomass pellets can be extensively used by rural residents.

  7. [Effects of Short-time Conservation Tillage Managements on Greenhouse Gases Emissions from Soybean-Winter Wheat Rotation System].

    Science.gov (United States)

    Xie, Yan; Chen, Xi; Hu, Zheng-hua; Chen, Shu-tao; Zhang, Han; Ling, Hui; Shen, Shuang-he

    2016-04-15

    Field experiments including one soybean growing season and one winter-wheat growing season were adopted. The experimental field was divided into four equal-area sub-blocks which differed from each other only in tillage managements, which were conventional tillage (T) , no-tillage with no straw cover ( NT) , conventional tillage with straw cover (TS) , and no-tillage with straw cover (NTS). CO₂ and N₂O emission fluxes from soil-crop system were measured by static chamber-gas chromatograph technique. The results showed that: compared with T, in the soybean growing season, NTS significantly increased the cumulative amount of CO₂ (CAC) from soil-soybean system by 27.9% (P = 0.045) during the flowering-podding stage, while NT significantly declined CAC by 28.9% (P = 0.043) during the grain filling-maturity stage. Compared with T, NT significantly declined the cumulative amount of N₂O (CAN) by 28.3% (P = 0.042) during the grain filling-maturity stage. In the winter-wheat growing season, compared with T, TS and NT significantly declined CAC by 24.3% (P = 0.032) and 36.0% (P = 0.041) during the elongation-booting stage, and also declined CAC by 26.8% (P = 0.027) and 33.1% (P = 0.038) during the maturity stage. During the turning-green stage, compared with T treatment, NT, NTS, and TS treatments had no significant effect on CAN, while NTS significant declined CAN by 42.0% (P = 0.035) compared with NT. Our findings suggested that conservation tillage managements had a more significant impact on CO₂ emission than 20 emission from soil-crop system.

  8. Wavelength comparison for laser induced breakdown spectroscopy caries detection

    Science.gov (United States)

    Amaral, Marcello M.; Raele, Marcus P.; Ana, Patrícia A.; Núñez, Sílvia C.; Zamataro, Claudia B.; Zezell, Denise M.

    2018-02-01

    Laser Induced Breakdown Spectroscopy (LIBS) is a technique capable to perform elemental analyses of a variety of samples, independent of matter state. Other spectroscopy techniques may require a destructive and time-consuming sample preparation. On the other hand, LIBS is a less destructive technique with no (or considerably less) sample preparation, using a relatively simple experimental setup. LIBS also provides a multielement analysis into one single spectrum acquisition, applying a Nd:YAG short-pulsed laser to ensure the stoichiometry between the sample and the generated plasma. LIBS have been applied on the study of carious lesions using a Nd:YAG into its fundamental emission at 1064 nm. It was shown that ratio of P/Ca and Zn/Ca can be used to monitor the cariogenic process. Another minor elements, e.g. C and Cu, associated with bacteria biofilm were also measured with the Nd:YAG laser. The fundamental wavelength emission (1064 nm) of Nd:YAG is coincident with a hydroxyapatite transmission window and it may affect the result. In order to address this issue a study used the second harmonic of the Nd:YAG laser at 532 nm. It was show that it is also possible perform LIBS on carious lesion using the Nd:YAG at 532 nm. However, there is not a work direct comparing the LIBS at 532 nm and 1064 nm for carious lesion detection. So, the aim of this work was to investigate the influence of laser wavelength on the LIBS performance for carious lesion detection. In both cases the carious lesion was detected with the advantage of no interference with hydroxyapatite at 532 nm.

  9. Relative impact of short-term emissions controls on gas and particle-phase oxidative potential during the 2015 China Victory Day Parade in Beijing, China

    Science.gov (United States)

    Huang, Wei; Fang, Dongqing; Shang, Jing; Li, Zhengqiang; Zhang, Yang; Huo, Peng; Liu, Zhaoying; Schauer, James J.; Zhang, Yuanxun

    2018-06-01

    A field observation focusing on reactive oxygen species (ROS) was conducted before, during, and after the 2015 China Victory Day Parade to understand the influence of short-term emissions controls on atmospheric oxidative activity. The hourly average concentrations of PM2.5, SO2, NO, NO2, CO, O3, as well as gas and particle-phase ROS, were measured using a series of online instruments. PM2.5 concentrations during control days were significantly lower than non-control days, which directly lead to the "Parade Blue", yet reductions of most gaseous pollutants except SO2 were not so obvious as PM. Similarly, the control measures also led to a great loss of particle-phase ROS throughout the control period, while the reduction of ROS in gas phase was not obvious until the more stringent measures implemented since September 1. Furthermore, only weak positive correlations were observed among ROS and some other measured species, indicating ROS concentrations were affected by a number of comprehensive factors that single marker could not capture. Meanwhile, meteorological condition and regional transportation were also shown to be the minor factors affecting atmospheric oxidizing capacity. The results of this observation mainly revealed the control measures were conducive to reducing particle-related ROS. However, the reduction of gas-phase ROS activity was less effective given the menu of controls employed for the 2015 China Victory Day Parade. Therefore, short-term emissions controls only aimed to PM reduction and visibility improvement will produce the blue sky but will not equivalently reduce the gas-phase ROS. Supplemental control measures will be needed to further reduce gas-phase ROS concentrations.

  10. Photoluminescence emission spectra of Makrofol® DE 1-1 upon irradiation with ultraviolet radiation

    Science.gov (United States)

    El Ghazaly, M.; Aydarous, Abdulkadir

    Photoluminescence (PL) emission spectra of Makrofol® DE 1-1 (bisphenol-A based polycarbonate) upon irradiation with ultraviolet radiation of different wavelengths were investigated. The absorption-and attenuation coefficient measurements revealed that the Makrofol® DE 1-1 is characterized by high absorbance in the energy range 6.53-4.43 eV but for a lower energy than 4.43 eV, it is approximately transparent. Makrofol® DE 1-1 samples were irradiated with ultraviolet radiation of wavelength in the range from 250 (4.28 eV) to 400 (3.10 eV) nm in step of 10 nm and the corresponding photoluminescence (PL) emission spectra were measured with a spectrofluorometer. It is found that the integrated counts and the peak height of the photoluminescence emission (PL) bands are strongly correlated with the ultraviolet radiation wavelength. They are increased at the ultraviolet radiation wavelength 280 nm and have maximum at 290 nm, thereafter they decrease and diminish at 360 nm of ultraviolet wavelength. The position of the PL emission band peak was red shifted starting from 300 nm, which increased with the increase the ultraviolet radiation wavelength. The PL bandwidth increases linearly with the increase of the ultraviolet radiation wavelength. When Makrofol® DE 1-1 is irradiated with ultraviolet radiation of short wavelength (UVC), the photoluminescence emission spectra peaks also occur in the UVC but of a relatively longer wavelength. The current new findings should be considered carefully when using Makrofol® DE 1-1 in medical applications related to ultraviolet radiation.

  11. Photoluminescence emission spectra of Makrofol® DE 1-1 upon irradiation with ultraviolet radiation

    Directory of Open Access Journals (Sweden)

    M. El Ghazaly

    Full Text Available Photoluminescence (PL emission spectra of Makrofol® DE 1-1 (bisphenol-A based polycarbonate upon irradiation with ultraviolet radiation of different wavelengths were investigated. The absorption-and attenuation coefficient measurements revealed that the Makrofol® DE 1-1 is characterized by high absorbance in the energy range 6.53–4.43 eV but for a lower energy than 4.43 eV, it is approximately transparent. Makrofol® DE 1-1 samples were irradiated with ultraviolet radiation of wavelength in the range from 250 (4.28 eV to 400 (3.10 eV nm in step of 10 nm and the corresponding photoluminescence (PL emission spectra were measured with a spectrofluorometer. It is found that the integrated counts and the peak height of the photoluminescence emission (PL bands are strongly correlated with the ultraviolet radiation wavelength. They are increased at the ultraviolet radiation wavelength 280 nm and have maximum at 290 nm, thereafter they decrease and diminish at 360 nm of ultraviolet wavelength. The position of the PL emission band peak was red shifted starting from 300 nm, which increased with the increase the ultraviolet radiation wavelength. The PL bandwidth increases linearly with the increase of the ultraviolet radiation wavelength. When Makrofol® DE 1-1 is irradiated with ultraviolet radiation of short wavelength (UVC, the photoluminescence emission spectra peaks also occur in the UVC but of a relatively longer wavelength. The current new findings should be considered carefully when using Makrofol® DE 1-1 in medical applications related to ultraviolet radiation. Keywords: Photoluminescence spectra, Makrofol® DE 1-1, UV–vis spectrophotometry, Attenuation coefficient, Ultraviolet radiation

  12. Effect of regional precursor emission controls on long-range ozone transport – Part 1: Short-term changes in ozone air quality

    Directory of Open Access Journals (Sweden)

    J. J. West

    2009-08-01

    Full Text Available Observations and models demonstrate that ozone and its precursors can be transported between continents and across oceans. We model the influences of 10% reductions in anthropogenic nitrogen oxide (NOx emissions from each of nine world regions on surface ozone air quality in that region and all other regions. In doing so, we quantify the relative importance of long-range transport between all source-receptor pairs, for direct short-term ozone changes. We find that for population-weighted concentrations during the three-month "ozone-season", the strongest inter-regional influences are from Europe to the Former Soviet Union, East Asia to Southeast Asia, and Europe to Africa. The largest influences per unit of NOx reduced, however, are seen for source regions in the tropics and Southern Hemisphere, which we attribute mainly to greater sensitivity to changes in NOx in the lower troposphere, and secondarily to increased vertical convection to the free troposphere in tropical regions, allowing pollutants to be transported further. Results show, for example, that NOx reductions in North America are ~20% as effective per unit NOx in reducing ozone in Europe during summer, as NOx reductions from Europe itself. Reducing anthropogenic emissions of non-methane volatile organic compounds (NMVOCs and carbon monoxide (CO by 10% in selected regions, can have as large an impact on long-range ozone transport as NOx reductions, depending on the source region. We find that for many source-receptor pairs, the season of greatest long-range influence does not coincide with the season when ozone is highest in the receptor region. Reducing NOx emissions in most source regions causes a larger decrease in export of ozone from the source region than in ozone production outside of the source region.

  13. Short-rotation forestry of birch, maple, poplar and willow in Flanders (Belgium) II. Energy production and CO2 emission reduction potential

    International Nuclear Information System (INIS)

    Walle, Inge van de; Camp, Nancy van; Casteele, Liesbet van de; Verheyen, Kris; Lemeur, Raoul

    2007-01-01

    Belgium, being an EU country, has committed itself to a 7.5% reduction of greenhouse gas emissions during the first commitment period of the Kyoto Protocol. Within this framework, the Flemish government aims at reaching a share of 6% of renewable electricity in the total electricity production by 2010. In this work, the biomass production of birch, maple, poplar and willow in a short-rotation forestry (SRF) plantation after a 4-year growth period served as the base to calculate the amount of (electrical) energy that could be produced by this type of bioenergy crop in Flanders. The maximum amount of electricity that could be provided by SRF biomass was estimated at 72.9 GWh e year -1 , which only accounts for 0.16% of the total electricity production in this region. Although the energy output was rather low, the bioenergy production process under consideration appeared to be more energy efficient than energy production processes based on fossil fuels. The high efficiency of birch compared to the other species was mainly due to the high calorific value of the birch wood. The maximum CO 2 emission reduction potential of SRF plantations in Flanders was estimated at only 0.09% of the total annual CO 2 emission. The most interesting application of SRF in Flanders seemed to be the establishment of small-scale plantations, linked to a local combined heat and power plant. These plantations could be established on marginal arable soils or on polluted sites, and they could be of importance in the densely populated area of Flanders because of other environmental benefits, among which their function as (temporary) habitat for many species

  14. Observation of a Short Period Quasi-periodic Pulsation in Solar X-Ray, Microwave, and EUV Emissions

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Pankaj; Cho, Kyung-Suk [Korea Astronomy and Space Science Institute (KASI), Daejeon, 305-348 (Korea, Republic of); Nakariakov, Valery M., E-mail: pankaj@kasi.re.kr [Centre for Fusion, Space and Astrophysics, Department of Physics, University of Warwick, CV4 7AL (United Kingdom)

    2017-02-10

    This paper presents the multiwavelength analysis of a 13 s quasi-periodic pulsation (QPP) observed in hard X-ray (12–300 keV) and microwave (4.9–34 GHz) emissions during a C-class flare that occurred on 2015 September 21. Atmospheric Image Assembly (AIA) 304 and 171 Å images show an emerging loop/flux tube (L1) moving radially outward, which interacts with the preexisting structures within the active region (AR). The QPP was observed during the expansion of and rising motion of L1. The Nobeyama Radioheliograph microwave images in 17/34 GHz channels reveal a single radio source that was co-spatial with a neighboring loop (L2). In addition, using AIA 304 Å images, we detected intensity oscillations in the legs of L2 with a period of about 26 s. A similar oscillation period was observed in the GOES soft X-ray flux derivative. This oscillation period seems to increase with time. We suggest that the observed QPP is most likely generated by the interaction between L2 and L3 observed in the AIA hot channels (131 and 94 Å). The merging speed of loops L2 and L3 was ∼35 km s{sup −1}. L1 was destroyed possibly by its interaction with preexisting structures in the AR, and produced a cool jet with the speed of ∼106–118 km s{sup −1} associated with a narrow CME (∼770 km s{sup −1}). Another mechanism of the QPP in terms of a sausage oscillation of the loop (L2) is also possible.

  15. The wavelength dependence of polarization in NGC 2023

    International Nuclear Information System (INIS)

    Rolph, C. D.; Scarrott, S. M.

    1989-01-01

    NGC 2023 is a bright reflection nebula illuminated by the central star HD37903. At 2 microns the nebula is seen solely by reflected light from the central star but in the NIR there is excess radiation that is supposed to arise from thermal emission from a population of small grains (Sellgren, 1984). The unexpectedly high surface brightness at R and I wavelengths has led to the suggestion that even at these wavelengths there is a significant contribution from this thermal emission process (Witt, Schild, and Kraiman, 1984). If the nebula is seen by reflected starlight then this radiation will be linearly polarized. The level of polarization depends on the scattering geometry, grain size distribution, etc., and is typically 20 to 40 percent for nebulae such as NGC 1999 which is morphologically similar to NGC 2023. If, in any waveband, there is a contribution of radiation from emission processes this radiation will be unpolarized and will serve to dilute the scattered radiation to give a lower level of observed polarization. A study of the wavelength dependence of polarization in nebulae in which there may be thermal emission from grains will indicate the contribution from this process to the total luminosity. Polarization maps were produced in BVRI wavebands for the NGC 2023 nebulosity which confirm that at all wavelengths it is a reflection nebula illuminated by a central star. The wavelength dependence of polarization at representative points in the nebula and in a scatter plot of polarization in V and I wavebands at all points at which measurements are given. Results indicate that throughout the nebula there is a general trend for the level of polarization to increase with wavelength and that maximum levels of polarization occur at the longest wavelengths. No evidence is seen in the data for any significant contribution from the thermal emission from grains in the BVRI luminosity of NGC 2023

  16. Pulsed hybrid dual wavelength Y-branch-DFB laser-tapered amplifier system suitable for water vapor detection at 965 nm with 16 W peak power

    Science.gov (United States)

    Vu, Thi N.; Klehr, Andreas; Sumpf, Bernd; Hoffmann, Thomas; Liero, Armin; Tränkle, Günther

    2016-03-01

    A master oscillator power amplifier system emitting alternatingly at two neighbored wavelengths around 965 nm is presented. As master oscillator (MO) a Y-branch DFB-laser is used. The two branches, which can be individually controlled, deliver the two wavelengths needed for a differential absorption measurement of water vapor. Adjusting the current through the DFB sections, the wavelength can be adjusted with respect to the targeted either "on" or "off" resonance, respectively wavelength λon or wavelength λoff. The emission of this laser is amplified in a tapered amplifier (TA). The ridge waveguide section of the TA acts as optical gate to generate short pulses with duration of 8 ns at a repetition rate of 25 kHz, the flared section is used for further amplification to reach peak powers up to 16 W suitable for micro-LIDAR (Light Detection and Ranging). The necessary pulse current supply user a GaN-transistor based driver electronics placed close to the power amplifier (PA). The spectral properties of the emission of the MO are preserved by the PA. A spectral line width smaller than 10 pm and a side mode suppression ratio (SMSR) of 37 dB are measured. These values meet the demands for water vapor absorption measurements under atmospheric conditions.

  17. Radiative flux calculations at UV and visible wavelengths

    International Nuclear Information System (INIS)

    Grossman, A.S.; Grant, K.E.; Wuebbles, D.J.

    1993-10-01

    A radiative transfer model to calculate the short wavelength fluxes at altitudes between 0 and 80 km has been developed at LLNL. The wavelength range extends from 175--735 nm. This spectral range covers the UV-B wavelength region, 250--350 nm, with sufficient resolution to allow comparison of UV-B measurements with theoretical predictions. Validation studies for the model have been made for both UV-B ground radiation calculations and tropospheric solar radiative forcing calculations for various ozone distributions. These studies indicate that the model produces results which agree well with respect to existing UV calculations from other published models

  18. Gradient decent based multi-objective cultural differential evolution for short-term hydrothermal optimal scheduling of economic emission with integrating wind power and photovoltaic power

    International Nuclear Information System (INIS)

    Zhang, Huifeng; Yue, Dong; Xie, Xiangpeng; Dou, Chunxia; Sun, Feng

    2017-01-01

    With the integration of wind power and photovoltaic power, optimal operation of hydrothermal power system becomes great challenge due to its non-convex, stochastic and complex-coupled constrained characteristics. This paper extends short-term hydrothermal system optimal model into short-term hydrothermal optimal scheduling of economic emission while considering integrated intermittent energy resources (SHOSEE-IIER). For properly solving SHOSEE-IIER problem, a gradient decent based multi-objective cultural differential evolution (GD-MOCDE) is proposed to improve the optimal efficiency of SHOSEE-IIER combined with three designed knowledge structures, which mainly enhances search ability of differential evolution in the shortest way. With considering those complex-coupled and stochastic constraints, a heuristic constraint-handling measurement is utilized to tackle with them both in coarse and fine tuning way, and probability constraint-handling procedures are taken to properly handle those stochastic constraints combined with their probability density functions. Ultimately, those approaches are implemented on five test systems, which testify the optimization efficiency of proposed GD-MOCDE and constraint-handling efficiency for system load balance, water balance and stochastic constraint-handling measurements, those obtained results reveal that the proposed GD-MOCDE can properly solve the SHOSEE-IIER problem combined with those constraint-handling approaches. - Highlights: • Gradient decent method is proposed to improve mutation operator. • Hydrothermal system is extended to hybrid energy system. • The uncertainty constraint is converted into deterministic constraint. • The results show the viability and efficiency of proposed algorithm.

  19. Topology optimised wavelength dependent splitters

    DEFF Research Database (Denmark)

    Hede, K. K.; Burgos Leon, J.; Frandsen, Lars Hagedorn

    A photonic crystal wavelength dependent splitter has been constructed by utilising topology optimisation1. The splitter has been fabricated in a silicon-on-insulator material (Fig. 1). The topology optimised wavelength dependent splitter demonstrates promising 3D FDTD simulation results....... This complex photonic crystal structure is very sensitive against small fabrication variations from the expected topology optimised design. A wavelength dependent splitter is an important basic building block for high-performance nanophotonic circuits. 1J. S. Jensen and O. Sigmund, App. Phys. Lett. 84, 2022...

  20. AWG Filter for Wavelength Interrogator

    Science.gov (United States)

    Black, Richard J. (Inventor); Costa, Joannes M. (Inventor); Faridian, Fereydoun (Inventor); Moslehi, Behzad (Inventor); Sotoudeh, Vahid (Inventor)

    2015-01-01

    A wavelength interrogator is coupled to a circulator which couples optical energy from a broadband source to an optical fiber having a plurality of sensors, each sensor reflecting optical energy at a unique wavelength and directing the reflected optical energy to an AWG. The AWG has a detector coupled to each output, and the reflected optical energy from each grating is coupled to the skirt edge response of the AWG such that the adjacent channel responses form a complementary pair response. The complementary pair response is used to convert an AWG skirt response to a wavelength.

  1. Dye mixtures for ultrafast wavelength shifters

    Energy Technology Data Exchange (ETDEWEB)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R. [Texas Tech Univ., Lubbock, TX (United States). Dept. of Physics; Barashkov, N. [Karpov Inst. of Physical Chemistry, Moscow (Russian Federation)

    1994-12-31

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations.

  2. Dye mixtures for ultrafast wavelength shifters

    International Nuclear Information System (INIS)

    Gangopadhyay, S.; Liu, L.; Palsule, C.; Borst, W.; Wigmans, R.

    1994-01-01

    Particle detectors based on scintillation processes have been used since the discovery of radium about 100 years ago. The fast signals that can be obtained with these detectors, although often considered a nice asset, were rarely essential for the success of experiments. However, the new generation of high energy particle accelerators require particle detectors with fast response time. The authors have produced fast wavelength shifters using mixtures of various Coumarin dyes with DCM in epoxy-polymers (DGEBA+HHPA) and measured the properties of these wavelength shifters. The particular mixtures were chosen because there is a substantial overlap between the emission spectrum of Coumarin and the absorption spectrum of DCM. The continuous wave and time-resolved fluorescence spectra have been studied as a function of component concentration to optimize the decay times, emission peaks and quantum yields. The mean decay times of these mixtures are in the range of 2.5--4.5 ns. The mean decay time increases with an increase in Coumarin concentration at a fixed DCM concentration or with a decrease in DCM concentration at a fixed Coumarin concentration. This indicates that the energy transfer is radiative at lower relative DCM concentrations and becomes non-radiative at higher DCM concentrations

  3. From laboratory to the sky: Th-Ar wavelength standards for the cryogenic infrared echelle spectrograph (CRIRES)

    Energy Technology Data Exchange (ETDEWEB)

    Kerber, Florian; Bristow, Paul [European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching (Germany); Nave, Gillian; Sansonetti, Craig J [National Institute of Standards and Technology, Gaithersburg, MD (United States)], E-mail: fkerber@eso.org, E-mail: gillian.nave@nist.gov, E-mail: craig.sansonetti@nist.gov, E-mail: bristowp@eso.org

    2009-05-15

    We report on the collaborative effort of the European Southern Observatory (ESO) and the National Institute of Standards and Technology (NIST) to establish-through laboratory measurements-wavelength standards in the near-infrared (IR) emission line spectrum of a low current Th-Ar hollow cathode lamp. These standards are now routinely used for the wavelength calibration of the cryogenic infrared echelle spectrograph (CRIRES) operated at one of the unit telescopes of the very large telescope (VLT) at ESO's La Silla Paranal Observatory in Chile. The availability of highly accurate wavelength standards from a commercially available calibration source permits a shift to a new operational paradigm for high-resolution IR spectroscopy. Wavelength calibration no longer has to rely on atmospheric features but can make use of laboratory traceable reference data as is normally done in the ultraviolet and visible regions. This opens the door for more quantitative spectroscopic work in the near-IR. To illustrate the potential impact of this development, we briefly review the current state of affairs in IR astronomy and its projected future. With the advent of the next generation of extremely large ground-based telescopes the IR region will become the most powerful window on the universe within the next 10-15 years. We conclude with a short outlook on the contribution atomic physics can make to this evolution.

  4. Short wavelength optics for future free electron lasers

    International Nuclear Information System (INIS)

    Attwood, D.T.

    1984-04-01

    Although much free-electron laser work is directed toward achieving sufficient single-pass gain to be useful for research purposes, the availability of mirrors of high reflectance for the vacuum ultraviolet and soft x-ray regime would make resonant cavities a possibility. In addition, as in ordinary synchrotron radiation work, mirrors are required for the construction of realistic experiments and for beam manipulation purposes such as folding and extraction. The Working Group discussed a number of approaches to reflecting optics for free electron lasers, which are summarized here, and described in some detail. 16 references, 2 figures

  5. Ultra-short wavelength x-ray system

    Science.gov (United States)

    Umstadter, Donald [Ann Arbor, MI; He, Fei [Ann Arbor, MI; Lau, Yue-Ying [Potomac, MD

    2008-01-22

    A method and apparatus to generate a beam of coherent light including x-rays or XUV by colliding a high-intensity laser pulse with an electron beam that is accelerated by a synchronized laser pulse. Applications include x-ray and EUV lithography, protein structural analysis, plasma diagnostics, x-ray diffraction, crack analysis, non-destructive testing, surface science and ultrafast science.

  6. Non-linear modulation of short wavelength compressional Alfven eigenmodes

    Energy Technology Data Exchange (ETDEWEB)

    Fredrickson, E. D.; Gorelenkov, N. N.; Podesta, M.; Gerhardt, S. P.; Bell, R. E.; Diallo, A.; LeBlanc, B. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Bortolon, A. [University of California, Irvine, California 92697 (United States); Crocker, N. A. [University of California, Los Angeles, California 90095 (United States); Levinton, F. M.; Yuh, H. [Nova Photonics, Princeton, New Jersey 08543 (United States)

    2013-04-15

    Most Alfvenic activity in the frequency range between toroidal Alfven eigenmodes and roughly one half of the ion cyclotron frequency on National Spherical Torus eXperiment [Ono et al., Nucl. Fusion 40, 557 (2000)], that is, approximately 0.3 MHz up to Almost-Equal-To 1.2 MHz, are modes propagating counter to the neutral beam ions. These have been modeled as Compressional and Global Alfven Eigenmodes (CAE and GAE) and are excited through a Doppler-shifted cyclotron resonance with the beam ions. There is also a class of co-propagating modes at higher frequency than the counter-propagating CAE and GAE. These modes have been identified as CAE, and are seen mostly in the company of a low frequency, n = 1 kink-like mode. In this paper, we present measurements of the spectrum of these high frequency CAE (hfCAE) and their mode structure. We compare those measurements to a simple model of CAE and present a predator-prey type model of the curious non-linear coupling of the hfCAE and the low frequency kink-like mode.

  7. Workshop on scientific applications of short wavelength coherent light sources

    International Nuclear Information System (INIS)

    Spicer, W.; Arthur, J.; Winick, H.

    1993-02-01

    This report contains paper on the following topics: A 2 to 4nm High Power FEL On the SLAC Linac; Atomic Physics with an X-ray Laser; High Resolution, Three Dimensional Soft X-ray Imaging; The Role of X-ray Induced Damage in Biological Micro-imaging; Prospects for X-ray Microscopy in Biology; Femtosecond Optical Pulses?; Research in Chemical Physics Surface Science, and Materials Science, with a Linear Accelerator Coherent Light Source; Application of 10 GeV Electron Driven X-ray Laser in Gamma-ray Laser Research; Non-Linear Optics, Fluorescence, Spectromicroscopy, Stimulated Desorption: We Need LCLS' Brightness and Time Scale; Application of High Intensity X-rays to Materials Synthesis and Processing; LCLS Optics: Selected Technological Issues and Scientific Opportunities; Possible Applications of an FEL for Materials Studies in the 60 eV to 200 eV Spectral Region

  8. Electron beam acceleration and compression for short wavelength FELs

    International Nuclear Information System (INIS)

    Raubenheimer, T.O.

    1994-11-01

    A single pass UV or X-ray FEL will require a low emittance electron beam with high peak current and relatively high beam energy, a few hundred MeV to many GeV. To achieve the necessary peak current and beam energy, the beams must be bunch compressed and they must be accelerated in long transport lines where dispersive and wakefield emittance dilutions are important. In this paper, we will describe the sources and significance of the dilutions during acceleration, bunch compression, and transport through the undulator. In addition, we will discuss sources of jitter, especially effects arising from the bunch compressions, and the possible cancellation techniques

  9. Ghostly Glow Reveals a Hidden Class of Long-Wavelength Radio Emitters

    Science.gov (United States)

    2008-10-01

    (Washington, DC. 08)- A team of scientists, including astronomers from the Naval Research Laboratory (NRL), have detected long wavelength radio emission from a colliding, massive galaxy cluster which, surprisingly, is not detected at the shorter wavelengths typically seen in these objects. The discovery implies that existing radio telescopes have missed a large population of these colliding objects. It also provides an important confirmation of the theoretical prediction that colliding galaxy clusters accelerate electrons and other particles to very high energies through the process of turbulent waves. The team revealed their findings in the October 16, 2008 edition of Nature. This new population of objects is most easily detected at long wavelengths. Professor Greg Taylor of the University of New Mexico and scientific director of the Long Wavelength Array (LWA) points out, "This result is just the tip of the iceberg. When an emerging suite of much more powerful low frequency telescopes, including the LWA in New Mexico, turn their views to the cosmos, the sky will 'light up' with hundreds or even thousands of colliding galaxy clusters." NRL has played a key role in promoting the development of this generation of new instruments and is currently involved with the development of the LWA. NRL radio astronomer and LWA Project Scientist Namir Kassim says "Our discovery of a previously hidden class of low frequency cluster-radio sources is particularly important since the study of galaxy clusters was a primary motivation for development of the LWA." The discovery of the emission in the galaxy cluster Abell 521 (or A521 for short) was made using the Giant Metrewave Radiotelescope (GMRT) in India, and its long wavelength nature was confirmed by the National Science Foundation's (NRAO) Very Large Array (VLA) radio telescope in New Mexico. The attached image shows the radio emission at a wavelength of 125cm in red superimposed on a blue image made from data taken by the

  10. Coherence techniques at extreme ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chang [Univ. of California, Berkeley, CA (United States)

    2002-01-01

    The renaissance of Extreme Ultraviolet (EUV) and soft x-ray (SXR) optics in recent years is mainly driven by the desire of printing and observing ever smaller features, as in lithography and microscopy. This attribute is complemented by the unique opportunity for element specific identification presented by the large number of atomic resonances, essentially for all materials in this range of photon energies. Together, these have driven the need for new short-wavelength radiation sources (e.g. third generation synchrotron radiation facilities), and novel optical components, that in turn permit new research in areas that have not yet been fully explored. This dissertation is directed towards advancing this new field by contributing to the characterization of spatial coherence properties of undulator radiation and, for the first time, introducing Fourier optical elements to this short-wavelength spectral region. The first experiment in this dissertation uses the Thompson-Wolf two-pinhole method to characterize the spatial coherence properties of the undulator radiation at Beamline 12 of the Advanced Light Source. High spatial coherence EUV radiation is demonstrated with appropriate spatial filtering. The effects of small vertical source size and beamline apertures are observed. The difference in the measured horizontal and vertical coherence profile evokes further theoretical studies on coherence propagation of an EUV undulator beamline. A numerical simulation based on the Huygens-Fresnel principle is performed.

  11. Interrogation of weak Bragg grating sensors based on dual-wavelength differential detection.

    Science.gov (United States)

    Cheng, Rui; Xia, Li

    2016-11-15

    It is shown that for weak Bragg gratings the logarithmic ratio of reflected intensities at any two wavelengths within the spectrum follows a linear relationship with the Bragg wavelength shift, with a slope proportional to their wavelength spacing. This finding is exploited to develop a flexible, efficient, and cheap interrogation solution of weak fiber Bragg grating (FBGs), especially ultra-short FBGs, in distributed sensing based on dual-wavelength differential detection. The concept is experimentally studied in both single and distributed sensing systems with ultra-short FBG sensors. The work may form the basis of new and promising FBG interrogation techniques based on detecting discrete rather than continuous spectra.

  12. FY 2000 report on the results of the regional consortium R and D project - Regional consortium energy R and D. Development of new vacuum ultraviolet area optical materials realizing next generation short wavelength optical lithography; 2000 nendo chiiki consortium kenkyu kaihatsu jigyo - chiiki consortium energy kenkyu kaihatsu. Jisedai tanhacho hikari lithography wo jitsugensuru shinku shigaiiki kogaku zairyo no kaihatsu seika hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2001-03-01

    As materials for next generation lithography use optical device using short wavelength light sources such as F{sub 2} and Ar{sub 2}, the development was proceeded with of fluoride monocrystal materials and 12-inch class large/high quality monocrystal production technology. Studies were made in the following five fields: 1) proposal/design of new materials and the heightening of performance: 2) establishment of the large/high quality crystal production method; 3) evaluation of optical properties and elucidation of micro-defect formation mechanism; 4) comprehensive investigational research; 5) study of the evaluation technology by vacuum ultraviolet area pulse light. In 1), for the development of the optimum materials, a lot of materials were tried to be monocrystallized, and the permeability was estimated by measuring the reflectance in the vacuum ultraviolet area. As to LiCaAlF{sub 6}, monocrystal with 1-inch diameter was made by the Bridgman method. In 2), studies were made of conditions for large crystal growth by the pull method, large crystal growth by the Bridgman method, and the structure of production equipment for crystals with larger diameter. (NEDO)

  13. Agility of Felix Regarding Wavelength and Micropulse Shape

    NARCIS (Netherlands)

    Bakker, R. J.; van der Geer, C. A. J.; Jaroszynski, D. A.; van der Meer, A. F. G.; Oepts, D.; van Amersfoort, P. W.; Anderegg, V.; van Son, P. C.

    1993-01-01

    The user-facility FELIX employs two FELs together covering the spectral range from 6.5 to 110 mum. Adjustment of the undulator strength permits wavelength tuning over a factor of two within two minutes while continuously providing several kilowatts of output power. As FELIX combines short electron

  14. Long-Wavelength Phonon Scattering in Nonpolar Semiconductors

    DEFF Research Database (Denmark)

    Lawætz, Peter

    1969-01-01

    The long-wavelength acoustic- and optical-phonon scattering of carriers in nonpolar semiconductors is considered from a general point of view. The deformation-potential approximation is defined and it is shown that long-range electrostatic forces give a nontrivial correction to the scattering...... of the very-short-range nature of interactions in a covalent semiconductor....

  15. Wavelength dependence of interstellar polarization

    International Nuclear Information System (INIS)

    Mavko, G.E.

    1974-01-01

    The wavelength dependence of interstellar polarization was measured for twelve stars in three regions of the Milky Way. A 120A bandpass was used to measure the polarization at a maximum of sixteen wavelengths evenly spaced between 2.78μ -1 (3600A) and 1.28μ -1 (7800A). For such a wide wavelength range, the wavelength resolution is superior to that of any previously reported polarization measurements. The new scanning polarimeter built by W. A. Hiltner of the University of Michigan was used for the observations. Very broad structure was found in the wavelength dependence of the polarization. Extensive investigations were carried out to show that the structure was not caused by instrumental effects. The broad structure observed is shown to be in agreement with concurrent extinction measurements for the same stars. Also, the observed structure is of the type predicted when a homogeneous silicate grain model is fitted to the observed extinction. The results are in agreement with the hypothesis that the very broad band structure seen in the extinction is produced by the grains. (Diss. Abstr. Int., B)

  16. Ionic liquids as solvents for Čerenkov counting and the effect of a wavelength shifter.

    Science.gov (United States)

    Mirenda, M; Rodrigues, D; Ferreyra, C; Arenillas, P; Sarmiento, G P; Krimer, N; Japas, M L

    2018-04-01

    We study the wavelength shift of the Čerenkov light - generated in the ionic liquid (BMIMCl) - caused by the addition of the highly fluorescent ionic liquid (BMIMHPTS). 18 F and 32 P efficiencies increases up to 124% and 14%, respectively, compared with the values obtained with pure BMIMCl. With this improvement, ionic liquid mixtures become a good alternative - when using the TDCR-Cherenkov technique - to standardize radionuclides having electron emissions energies close to the threshold energy in water (∼ 260keV). As an advantage compared with other solvents, the Ionic liquid mixture can be reused, in the case of short-lived radionuclides, by simply removing all water content in a vacuum oven. Copyright © 2017 Elsevier Ltd. All rights reserved.

  17. Selection of Quantum Dot Wavelengths for Biomedical Assays and Imaging

    Directory of Open Access Journals (Sweden)

    Yong Taik Lim

    2003-01-01

    Full Text Available Fluorescent semiconductor nanocrystals (quantum dots [QDs] are hypothesized to be excellent contrast agents for biomedical assays and imaging. A unique property of QDs is that their absorbance increases with increasing separation between excitation and emission wavelengths. Much of the enthusiasm for using QDs in vivo stems from this property, since photon yield should be proportional to the integral of the broadband absorption. In this study, we demonstrate that tissue scatter and absorbance can sometimes offset increasing QD absorption at bluer wavelengths, and counteract this potential advantage. By using a previously validated mathematical model, we explored the effects of tissue absorbance, tissue scatter, wavelength dependence of the scatter, water-to- hemoglobin ratio, and tissue thickness on QD performance. We conclude that when embedded in biological fluids and tissues, QD excitation wavelengths will often be quite constrained, and that excitation and emission wavelengths should be selected carefully based on the particular application. Based on our results, we produced near-infrared QDs optimized for imaging surface vasculature with white light excitation and a silicon CCD camera, and used them to image the coronary vasculature in vivo. Taken together, our data should prove useful in designing fluorescent QD contrast agents optimized for specific biomedical applications.

  18. Wavelength conversion techniques and devices

    DEFF Research Database (Denmark)

    Danielsen, Søren Lykke; Mikkelsen, Benny; Hansen, Peter Bukhave

    1997-01-01

    Taking into account the requirements to the converters e.g., bit rate transparency (at least up to 10 Gbit/s), polarisation independence, wavelength independence, moderate input power levels, high signal-to-noise ratio and high extinction ratio interferometric wavelength convertors are very...... interesting for use in WDM optical fibre networks. However, the perfect converter has probably not yet been fabricated and new techniques such as conversion relying on cross-absorption modulation in electro-absorption modulators might also be considered in pursue of effective conversion devices...

  19. Proportion of influence phases anatase and rutile TiO{sub 2} in the photoluminescence 538 nm emission wavelength; Influencia da proporcao das fases anatasio e rutilo na fotoluminescincia do TiO{sub 2} em comprimento de onda de emissao de 538 nm

    Energy Technology Data Exchange (ETDEWEB)

    Araujo, D.S.; Diniz, V.C.S.; Araujo, P.M.A.G.; Costa, A.C.F.M., E-mail: dagobertoufcg@gmail.com [Universidade Federal de Campina Grande (UFCG), PB (Brazil); Viana, R.S.; Junior, S.A. [Universidade Federal de Pernambuco (UFPE), PE (Brazil)

    2016-07-01

    TiO2 is one of the most studied materials in the technology area, especially in photoluminescent applications involving catalysts from the biosensor. Therefore, we propose to obtain the Pechini method TiO{sub 2} molar ratio of citric acid/metal ions of 3:1 and 4:1 in order to investigate the influence of the proportion of anatase and rutile phases with the photoluminescence excitation wavelength of 538nm emission. The samples were characterized by X-ray diffraction, thermal analysis and excitation spectroscopy. The results indicate the presence of two phases, with a proportion of 78.99 and 83.58 and 21.01% of anatase and rutile 16.42%, density 3.82 and 3.70 g/cm{sup 3} and excitement in length wave emission 538nm with maximum intensity 91289.2 and 71880,7 cps for samples 3:1 and 4:1, respectively. Sample 3:1 with the highest percentage of rutile phase favored photoluminescence. (author)

  20. Wavelength tuning of porous silicon microcavities

    International Nuclear Information System (INIS)

    Mulders, J.; Reece, P.; Zheng, W.H.; Lerondel, G.; Sun, B.; Gal, M.

    2002-01-01

    Full text: In the last decade much attention has been given to porous silicon (PS) for optoelectronic applications, which include efficient room temperature light emission as well as microcavity formation. Due to the large specific surface area, the use of porous silicon microcavities (PSMs) has been proposed for chemical sensing. Large wavelength shifts have indicated that the optical properties of PSMs are indeed strongly dependent on the environment. In this paper, we report the shifting of the resonance frequency of high quality PSMs, with the aim of tuning a future PS device to a certain required wavelength. The PSM samples were prepared by anodically etching p + -doped (5mΩcm) bulk silicon wafer in a solution (25%) of aqueous HF and ethanol. The device structure consisted of a PS layer sandwiched between 2 stacks of thin PS layers with alternating high and low effective refractive indices (RI), i.e. distributed Bragg mirrors (DBM). The layer thickness depends on the etch time while the porosity and hence refractive index is determined by the current density as the Si is etched. The position and the width of the stop-band can be fully controlled by the design of the DBMs, with the microcavity resonance mode sitting within the stop-band. We achieved tuning of the microcavity resonance by a number of methods, including temperature dependent tuning. The temperature induced wavelength shift was found to be of the order of 10 -15 nm. Computer modeling of these changes in the reflectivity spectra allowed us to quantify the changes of the effective refractive index and the respective layer thicknesses

  1. Underdense radiation sources: Moving towards longer wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Back, C.A.; Kilkenny, J.D. [General Atomics, San Diego, California (United States); Seely, J.F.; Weaver, J.L. [Naval Research Laboratory, Washington, DC (United States); Feldman, U. [Artep Inc., Ellicott City, MD (United States); Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A. [Lawrence Livermore National Laboratory, California (United States); Tillack, M. [U. C. San Diego, La Jolla, CA (United States)

    2006-06-15

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO{sub 2} aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  2. Underdense radiation sources: Moving towards longer wavelengths

    International Nuclear Information System (INIS)

    Back, C.A.; Kilkenny, J.D.; Seely, J.F.; Weaver, J.L.; Feldman, U.; Tommasini, R.; Glendinning, S.G.; Chung, H.K.; Rosen, M.; Lee, R.W.; Scott, H.A.; Tillack, M.

    2006-01-01

    Underdense radiation sources have been developed to provide efficient laboratory multi-keV radiation sources for radiography and radiation hardening studies. In these plasmas laser absorption by inverse Bremsstrahlung leads to high x-ray conversion efficiency because of efficient ionization of the low density aerogel or gas targets. Now we performing experiments in the soft x-ray energy regime where the atomic physics models are much more complicated. In recent experiments at the NIKE laser, we have irradiated a Ti-doped SiO 2 aerogel with up to 1650 J of 248 nm wavelength light. The absolute Ti L-shell emission in the 200-800 eV range is measured with a diagnostic that uses a transmission grating coupled to Si photodiodes. We will give an overview of the temporally-resolved absolutely calibrated spectra obtained over a range of conditions. (authors)

  3. Intensities of decimetric-wavelength radio recombination lines

    International Nuclear Information System (INIS)

    Parrish, A.; Pankonin, V.

    1975-01-01

    We summarize the intensity results of some of the 221 and 248α recombination-line observations taken with the Arecibo telescope, and report additional results including 166α observations from the NRAO 300-foot (91 m) telescope. The brightness temperatures of these lines increase sharply with wavelength. We show that these results require that the upper levels of the recombining atoms be overpopulated with respect to LTE conditions. The most reasonable interpretation of the results is that the line emission at these decimetric wavelengths is stimulated by a background source of continuum radiation

  4. Atmospheric emissions of Cu and Zn from coal combustion in China: Spatio-temporal distribution, human health effects, and short-term prediction.

    Science.gov (United States)

    Li, Rui; Li, Junlin; Cui, Lulu; Wu, Yu; Fu, Hongbo; Chen, Jianmin; Chen, Mindong

    2017-10-01

    China has become the largest coal consumer and important emitter of trace metals in the world. A multiple-year inventory of atmospheric copper (Cu) and zinc (Zn) emissions from coal combustion in 30 provinces of China and 4 economic sectors (power plant, industry sector, residential sector, and others) for the period of 1995-2014 has been calculated. The results indicated that the total emissions of Cu and Zn increased from 5137.70 t and 11484.16 t in 1995-7099.24 t and 14536.61 t in 2014, at an annual average growth rate of 1.90% and 1.33%, respectively. The industrial sector ranked as the leading source, followed by power plants, the residential use, and other sectors. The emissions of Cu and Zn were predominantly concentrated in the northern and eastern regions of China due to the enormous consumption of coal by the industrial and the power sectors. The emissions of Cu and Zn were closely associated with mortality and life expectancy (LE) on the basis of multiple regression analysis. Spatial econometric models suggested that Cu and Zn emissions displayed significantly positive relevance with mortality, while they exhibited negative correlation with LE. The influence of the Cu emission peaked in the north of China for both mortality and LE, while the impacts of the Zn emission on mortality and LE reached a maximum value in Xinjiang Province. The results of the grey prediction model suggested that the Cu emission would decrease to 5424.73 t, whereas the Zn emissions could reach 17402.13 t in 2020. Analysis of more specific data are imperative in order to estimate the emissions of both metals, to assess their human health effects, and then to adopt effective measures to prevent environmental pollution. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Wavelength stabilized multi-kW diode laser systems

    Science.gov (United States)

    Köhler, Bernd; Unger, Andreas; Kindervater, Tobias; Drovs, Simon; Wolf, Paul; Hubrich, Ralf; Beczkowiak, Anna; Auch, Stefan; Müntz, Holger; Biesenbach, Jens

    2015-03-01

    We report on wavelength stabilized high-power diode laser systems with enhanced spectral brightness by means of Volume Holographic Gratings. High-power diode laser modules typically have a relatively broad spectral width of about 3 to 6 nm. In addition the center wavelength shifts by changing the temperature and the driving current, which is obstructive for pumping applications with small absorption bandwidths. Wavelength stabilization of high-power diode laser systems is an important method to increase the efficiency of diode pumped solid-state lasers. It also enables power scaling by dense wavelength multiplexing. To ensure a wide locking range and efficient wavelength stabilization the parameters of the Volume Holographic Grating and the parameters of the diode laser bar have to be adapted carefully. Important parameters are the reflectivity of the Volume Holographic Grating, the reflectivity of the diode laser bar as well as its angular and spectral emission characteristics. In this paper we present detailed data on wavelength stabilized diode laser systems with and without fiber coupling in the spectral range from 634 nm up to 1533 nm. The maximum output power of 2.7 kW was measured for a fiber coupled system (1000 μm, NA 0.22), which was stabilized at a wavelength of 969 nm with a spectral width of only 0.6 nm (90% value). Another example is a narrow line-width diode laser stack, which was stabilized at a wavelength of 1533 nm with a spectral bandwidth below 1 nm and an output power of 835 W.

  6. Cycle 24 COS FUV Internal/External Wavelength Scale Monitor

    Science.gov (United States)

    Fischer, William J.

    2018-02-01

    We report on the monitoring of the COS FUV wavelength scale zero-points during Cycle 24 in program 14855. Select cenwaves were monitored for all FUV gratings at Lifetime Position 3. The target and cenwaves have remained the same since Cycle 21, with a change only to the target acquisition sequence. All measured offsets are within the error goals, although the G140L cenwaves show offsets at the short-wavelength end of segment A that are approaching the tolerance. This behavior will be closely monitored in subsequent iterations of the program.

  7. Aluminum nitride nanophotonic circuits operating at ultraviolet wavelengths

    Energy Technology Data Exchange (ETDEWEB)

    Stegmaier, M.; Ebert, J.; Pernice, W. H. P., E-mail: wolfram.pernice@kit.edu [Institute of Nanotechnology, Karlsruhe Institute of Technology, 76133 Karlsruhe (Germany); Meckbach, J. M.; Ilin, K.; Siegel, M. [Institute of Micro- und Nanoelectronic Systems, Karlsruhe Institute of Technology, 76187 Karlsruhe (Germany)

    2014-03-03

    Aluminum nitride (AlN) has recently emerged as a promising material for integrated photonics due to a large bandgap and attractive optical properties. Exploiting the wideband transparency, we demonstrate waveguiding in AlN-on-Insulator circuits from near-infrared to ultraviolet wavelengths using nanophotonic components with dimensions down to 40 nm. By measuring the propagation loss over a wide spectral range, we conclude that both scattering and absorption of AlN-intrinsic defects contribute to strong attenuation at short wavelengths, thus providing guidelines for future improvements in thin-film deposition and circuit fabrication.

  8. Solutions for ultra-high speed optical wavelength conversion and clock recovery

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2006-01-01

    This paper reports on our recent advances in ultra-fast optical communications relying on ultra-short pulses densely stacked in ultra-high bit rate serial data signals at a single wavelength. The paper describes details in solutions for the network functionalities of wavelength conversion and clock...... recovery at bit rates up to 320 Gb/s...

  9. [Fundus autofluorescence in patients with inherited retinal diseases : Patterns of fluorescence at two different wavelengths.

    NARCIS (Netherlands)

    Theelen, T.; Boon, C.J.F.; Klevering, B.J.; Hoyng, C.B.

    2008-01-01

    BACKGROUND: Fundus autofluorescence (FAF) may be excited and measured at different wavelengths. In the present study we compared short wavelength and near-infrared FAF patterns of retinal dystrophies. METHODS: We analysed both eyes of 108 patients with diverse retinal dystrophies. Besides colour

  10. 100G shortwave wavelength division multiplexing solutions for multimode fiber data links

    DEFF Research Database (Denmark)

    Cimoli, Bruno; Estaran Tolosa, Jose Manuel; Rodes Lopez, Guillermo Arturo

    2016-01-01

    We investigate an alternative 100G solution for optical short-range data center links. The presented solution adopts wavelength division multiplexing technology to transmit four channels of 25G over a multimode fiber. A comparative performance analysis of the wavelength-grid selection for the wav...

  11. Cluster dynamics at different cluster size and incident laser wavelengths

    International Nuclear Information System (INIS)

    Desai, Tara; Bernardinello, Andrea

    2002-01-01

    X-ray emission spectra from aluminum clusters of diameter -0.4 μm and gold clusters of dia. ∼1.25 μm are experimentally studied by irradiating the cluster foil targets with 1.06 μm laser, 10 ns (FWHM) at an intensity ∼10 12 W/cm 2 . Aluminum clusters show a different spectra compared to bulk material whereas gold cluster evolve towards bulk gold. Experimental data are analyzed on the basis of cluster dimension, laser wavelength and pulse duration. PIC simulations are performed to study the behavior of clusters at higher intensity I≥10 17 W/cm 2 for different size of the clusters irradiated at different laser wavelengths. Results indicate the dependence of cluster dynamics on cluster size and incident laser wavelength

  12. Secondary Emission From Synthetic Opal Infiltrated by Colloidal Gold and Glycine

    International Nuclear Information System (INIS)

    Dovbeshko, G.I.; Fesenko, O.M.; Boyko, V.V.; Romanyuk, V.R.; Gorelik, V.S.; Moiseyenko, V.N.; Sobolev, V.B.; Shvalagin, V.V.

    2012-01-01

    A comparison of the secondary emission (photoluminescence) and Bragg reflection spectra of photonic crystals (PC), namely, synthetic opals, opals infiltrated by colloidal gold, glycine, and a complex of colloidal gold with glycine is performed. The infiltration of colloidal gold and a complex of colloidal gold with glycine into the pores of PC causes a short-wavelength shift (about 5-15 nm) of the Bragg reflection and increases the intensity of this band by 1.5-3 times. In photoluminescence, the infiltration of PC by colloidal gold and colloidal gold with glycine suppresses the PC emission band near 375-450 nm and enhances the shoulder of the stop-zone band of PC in the region of 470-510 nm. The shape of the observed PC emission band connected with defects in synthetic opal is determined by the type of infiltrates and the excitation wavelength. Possible mechanisms of the effects are discussed.

  13. Effect of biochar addition on short-term N2O and CO2 emissions during repeated drying and wetting of an anthropogenic alluvial soil.

    Science.gov (United States)

    Yang, Fang; Lee, Xinqing; Theng, Benny K G; Wang, Bing; Cheng, Jianzhong; Wang, Qian

    2017-06-01

    Agricultural soils are an important source of greenhouse gases (GHG). Biochar application to such soils has the potential of mitigating global anthropogenic GHG emissions. Under irrigation, the topsoils in arid regions experience repeated drying and wetting during the crop growing season. Biochar incorporation into these soils would change the soil microbial environment and hence affect GHG emissions. Little information, however, is available regarding the effect of biochar addition on carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) emissions from agricultural soils undergoing repeated drying and wetting. Here, we report the results of a 49-day aerobic incubation experiment, incorporating biochar into an anthropogenic alluvial soil in an arid region of Xinjiang Province, China, and measuring CO 2 and N 2 O emissions. Under both drying-wetting and constantly moist conditions, biochar amendment significantly increased cumulative CO 2 emission. At the same time, there was a significant reduction (up to ~20 %) in cumulative N 2 O emission, indicating that the addition of biochar to irrigated agricultural soils may effectively slow down global warming in arid regions of China.

  14. Experimental investigation of the cascadability of a cross-gain modulation wavelength converter

    DEFF Research Database (Denmark)

    Zheng, Xueyan; Liu, Fenghai; Kloch, Allan

    2000-01-01

    by adding a fiber grating-based optical add-drop multiplexer after the semiconductor optical amplifier (SOA) to enhance the high-frequency response of the wavelength converter. However, the low-frequency degradation of the signal together with amplified spontaneous emission (ASE) noise and jitter......The cascading characteristics of a wavelength converter based on cross-gain modulation (XGM) are studied experimentally using a recirculating loop at 10 Gb/s. The maximum cascaded number of the wavelength converter converting the signal to the same wavelength is improved from five to eight...

  15. Dual-wavelength phase-shifting digital holography selectively extracting wavelength information from wavelength-multiplexed holograms.

    Science.gov (United States)

    Tahara, Tatsuki; Mori, Ryota; Kikunaga, Shuhei; Arai, Yasuhiko; Takaki, Yasuhiro

    2015-06-15

    Dual-wavelength phase-shifting digital holography that selectively extracts wavelength information from five wavelength-multiplexed holograms is presented. Specific phase shifts for respective wavelengths are introduced to remove the crosstalk components and extract only the object wave at the desired wavelength from the holograms. Object waves in multiple wavelengths are selectively extracted by utilizing 2π ambiguity and the subtraction procedures based on phase-shifting interferometry. Numerical results show the validity of the proposed technique. The proposed technique is also experimentally demonstrated.

  16. MULTI-WAVELENGTH AFTERGLOWS OF FAST RADIO BURSTS

    International Nuclear Information System (INIS)

    Yi, Shuang-Xi; Gao, He; Zhang, Bing

    2014-01-01

    The physical origin of fast radio bursts (FRBs) is unknown. Detecting electromagnetic counterparts to FRBs in other wavelengths is essential to measure their distances and to determine their physical origin. Assuming that at least some of them are of cosmological origin, we calculate their afterglow light curves in multiple wavelengths (X-rays, optical, and radio) by assuming a range of total kinetic energies and redshifts. We focus on forward shock emission, but also consider the possibility that some of the FRBs might have bright reverse shock emission. In general, FRB afterglows are too faint to be detected by current detectors. Only if an FRB has a very low radiative efficiency in radio (hence, a very large kinetic energy), and when it is close enough to observe can its afterglow be detected in the optical and radio bands. We discuss observational strategies for detecting these faint afterglows using future telescopes such as Large Synoptic Survey Telescope and Expanded Very Large Array

  17. Measurement of short bunches

    International Nuclear Information System (INIS)

    Wang, D.X.

    1996-01-01

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, and advanced accelerators such as laser or plasma wakefield accelerators. One would like to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, and accurate timing. Meanwhile, recent development and advances in RF photoinjectors and various bunching schemes make it possible to generate very short electron bunches. Measuring the longitudinal profile and monitoring bunch length are critical to understand the bunching process and longitudinal beam dynamics, and to commission and operate such short bunch machines. In this paper, several commonly used measurement techniques for subpicosecond bunches and their relative advantages and disadvantages are discussed. As examples, bunch length related measurements at Jefferson Lab are presented. At Jefferson Lab, bunch lengths as short as 84 fs have been systematically measured using a zero-phasing technique. A highly sensitive Coherent Synchrotron Radiation (CSR) detector has been developed to noninvasively monitor bunch length for low charge bunches. Phase transfer function measurements provide a means of correcting RF phase drifts and reproducing RF phases to within a couple of tenths of a degree. The measurement results are in excellent agreement with simulations. A comprehensive bunch length control scheme is presented. (author)

  18. Measurement of short bunches

    International Nuclear Information System (INIS)

    Wang, D.X.

    1996-01-01

    In recent years, there has been increasing interest in short electron bunches for different applications such as short wavelength FELs, linear colliders, and advanced accelerators such as laser or plasma wakefield accelerators. One would like to meet various requirements such as high peak current, low momentum spread, high luminosity, small ratio of bunch length to plasma wavelength, and accurate timing. Meanwhile, recent development and advances in RF photoinjectors and various bunching schemes make it possible to generate very short electron bunches. Measuring the longitudinal profile and monitoring bunch length are critical to understand the bunching process and longitudinal beam dynamics, and to commission and operate such short bunch machines. In this paper, several commonly used measurement techniques for subpicosecond bunches and their relative advantages and disadvantages are discussed. As examples, bunch length related measurements at Jefferson lab are presented. At Jefferson Lab, bunch lengths s short as 84 fs have been systematically measured using a zero-phasing technique. A highly sensitive Coherent Synchrotron Radiation (CSR) detector has been developed to noninvasively monitor bunch length for low charge bunches. Phase transfer function measurements provide a means of correcting RF phase drifts and reproducing RF phases to within a couple of tenths of a degree. The measurement results are in excellent agreement with simulations. A comprehensive bunch length control scheme is presented

  19. An advanced method of contributing emissions to short-lived chemical species (OH and HO2: the TAGGING 1.1 submodel based on the Modular Earth Submodel System (MESSy 2.53

    Directory of Open Access Journals (Sweden)

    V. S. Rieger

    2018-06-01

    Full Text Available To mitigate the human impact on climate change, it is essential to determine the contribution of emissions to the concentration of trace gases. In particular, the source attribution of short-lived species such as OH and HO2 is important as they play a crucial role for atmospheric chemistry. This study presents an advanced version of a tagging method for OH and HO2 (HOx which attributes HOx concentrations to emissions. While the former version (V1.0 only considered 12 reactions in the troposphere, the new version (V1.1, presented here, takes 19 reactions in the troposphere into account. For the first time, the main chemical reactions for the HOx chemistry in the stratosphere are also regarded (in total 27 reactions. To fully take into account the main HO2 source by the reaction of H and O2, the tagging of the H radical is introduced. In order to ensure the steady-state assumption, we introduce rest terms which balance the deviation of HOx production and loss. This closes the budget between the sum of all contributions and the total concentration. The contributions to OH and HO2 obtained by the advanced tagging method V1.1 deviate from V1.0 in certain source categories. For OH, major changes are found in the categories biomass burning, biogenic emissions and methane decomposition. For HO2, the contributions differ strongly in the categories biogenic emissions and methane decomposition. As HOx reacts with ozone (O3, carbon monoxide (CO, reactive nitrogen compounds (NOy, non-methane hydrocarbons (NMHCs and peroxyacyl nitrates (PAN, the contributions to these species are also modified by the advanced HOx tagging method V1.1. The contributions to NOy, NMHC and PAN show only little change, whereas O3 from biogenic emissions and methane decomposition increases in the tropical troposphere. Variations for CO from biogenic emissions and biomass burning are only found in the Southern Hemisphere.

  20. Millimetre wavelength methanol masers survey towards massive star forming regions

    Science.gov (United States)

    Umemoto, T.; Mochizuki, N.; Shibata, K. M.; Roh, D.-G.; Chung, H.-S.

    2007-03-01

    We present the results of a mm wavelength methanol maser survey towards massive star forming regions. We have carried out Class II methanol maser observations at 86.6 GHz, 86.9 GHz and 107.0 GHz, simultaneously, using the Nobeyama 45 m telescope. We selected 108 6.7 GHz methanol maser sources with declinations above -25 degrees and fluxes above 20 Jy. The detection limit of maser observations was ~3 Jy. Of the 93 sources surveyed so far, we detected methanol emission in 25 sources (27%) and “maser” emission in nine sources (10%), of which thre “maser” sources are new detections. The detection rate for maser emission is about half that of a survey of the southern sky (Caswell et al. 2000). There is a correlation between the maser flux of 107 GHz and 6.7 GHz/12 GHz emission, but no correlation with the “thermal” (non maser) emission. From results of other molecular line observations, we found that the sources with methanol emission show higher gas temperatures and twice the detection rate of SiO emission. This may suggest that dust evaporation and destruction by shock are responsible for the high abundance of methanol molecules, one of the required physical conditions for maser emission.

  1. Comparison of different wavelength pump sources for Tm subnanosecond amplifier

    Science.gov (United States)

    Cserteg, Andras; Guillemet, Sébastien; Hernandez, Yves; Giannone, Domenico

    2012-06-01

    We report here a comparison of different pumping wavelengths for short pulse Thulium fibre amplifiers. We compare the results in terms of efficiency and required fibre length. As we operate the laser in the sub-nanosecond regime, the fibre length is a critical parameter regarding non linear effects. With 793 nm clad-pumping, a 4 m long active fibre was necessary, leading to strong spectral deformation through Self Phase Modulation (SPM). Core-pumping scheme was then more in-depth investigated with several wavelengths tested. Good results with Erbium and Raman shifted pumping sources were obtained, with very short fibre length, aiming to reach a few micro-joules per pulse without (or with limited) SPM.

  2. Optogalvanic wavelength calibration for laser monitoring of reactive atmospheric species

    Science.gov (United States)

    Webster, C. R.

    1982-01-01

    Laser-based techniques have been successfully employed for monitoring atmospheric species of importance to stratospheric ozone chemistry or tropospheric air quality control. When spectroscopic methods using tunable lasers are used, a simultaneously recorded reference spectrum is required for wavelength calibration. For stable species this is readily achieved by incorporating into the sensing instrument a reference cell containing the species to be monitored. However, when the species of interest is short-lived, this approach is unsuitable. It is proposed that wavelength calibration for short-lived species may be achieved by generating the species of interest in an electrical or RF discharge and using optogalvanic detection as a simple, sensitive, and reliable means of recording calibration spectra. The wide applicability of this method is emphasized. Ultraviolet, visible, or infrared lasers, either CW or pulsed, may be used in aircraft, balloon, or shuttle experiments for sensing atoms, molecules, radicals, or ions.

  3. Comment on “Short-term combined economic emission scheduling of hydrothermal power systems with cascaded reservoirs using differential evolution” by K.K. Mandal and N. Chakaborty [Energy Convers. Manage. 50 (2009) 97–104

    International Nuclear Information System (INIS)

    Ahmadi, Abdollah; Nezhad, Ali Esmaeel

    2015-01-01

    This paper discusses the short-term combined economic emission scheduling of hydrothermal power systems with cascaded reservoirs [Energy Convers Manage. 50 (2009) 97–104], while differential evolution algorithm has been employed to solve the optimization problem. However, this problem is subjected to several constraints like the generation limitations of generating units. The solutions reported in the original paper do not satisfy the constraint on the initial and final reservoir storage volumes of hydro units as well as the constraint on the generated power by such units, which should be positive at any time of the scheduling period. Thus, this paper intends to prove this issue and solve the problem using Normal Boundary Intersection (NBI) method, in order to propose the correct solutions satisfying all the constraints of the short-term hydrothermal scheduling problem

  4. Locked into Copenhagen pledges - Implications of short-term emission targets for the cost and feasibility of long-term climate goals

    NARCIS (Netherlands)

    Riahi, Keywan; Kriegler, Elmar; Johnson, Nils; Bertram, Christoph; den Elzen, Michel; Eom, Jiyong; Schaeffer, Michiel; Edmonds, Jae; Isaac, Morna; Krey, Volker; Longden, Thomas; Luderer, Gunnar; Méjean, Aurélie; McCollum, David L.; Mima, Silvana; Turton, Hal; van Vuuren, Detlef P.; Wada, Kenichi; Bosetti, Valentina; Capros, Pantelis; Criqui, Patrick; Hamdi-Cherif, Meriem; Kainuma, Mikiko; Edenhofer, Ottmar

    2015-01-01

    This paper provides an overview of the AMPERE modeling comparison project with focus on the implications of near-term policies for the costs and attainability of long-term climate objectives. Nine modeling teams participated in the project to explore the consequences of global emissions following

  5. Making Displaced Holograms At Two Wavelengths

    Science.gov (United States)

    Witherow, William K.; Ecker, Andreas

    1989-01-01

    Two-wavelength holographic system augmented with pair of prisms to introduce small separation between holograms formed simultaneously at two wavelengths on holographic plate. Principal use in study of flows. Gradients in index of refraction of fluid caused by variations in temperature, concentration, or both. Holography at one wavelength cannot be used to distinguish between two types of variations. Difference between spacings of fringes in photographs reconstructed from holograms taken simultaneously at two different wavelengths manipulated mathematically to determine type of variation.

  6. Dual-wavelength erbium-doped fiber laser with asymmetric fiber Bragg grating Fabry-Perot cavity

    Science.gov (United States)

    Chen, Cong; Xu, Zhi-wei; Wang, Meng; Chen, Hai-yan

    2014-11-01

    A novel dual-wavelength fiber laser with asymmetric fiber Bragg grating (FBG) Fabry-Perot (FP) cavity is proposed and experimentally demonstrated. A couple of uniform FBGs are used as the cavity mirrors, and the third FBG is used as intracavity wavelength selector by changing its operation temperature. Experimental results show that by adjusting the operation temperature of the intracavity wavelength selector, a tunable dual-wavelength laser emission can be achieved. The results demonstrate the new concept of dual-wavelength lasing with asymmetric FBG FP resonator and its technical feasibility.

  7. Emission Behavior of Crystalline 1,4-Bis(4-phenylthiophene-2-yl)benzene Film Under Optical Excitation with Ultra Short Pulses.

    Science.gov (United States)

    Mochizuki, Hiroyuki; Kawaguchi, Yoshizo; Sasaki, Fumio; Hotta, Shu

    2016-04-01

    We evaluated emission behaviors of crystallized films of 1,4-bis(5-phenylthiophene-2-yl)benzene (AC5) in detail which was a representative thiophene/phenylene co-oligomer. The crystallized AC5 films were prepared by vapor deposition onto a substrate and thermal treatment. The AC5 films consisted of a crystalline domain with the size of several tens of micrometers. We used femtosecond laser pulses for the excitation of the AC5 films. As a result, the femtosecond laser pulses did not induce re-absorption above excitation energy densities of their laser threshold. The obtained gain value for AC5 crystallized film was large, over 150 cm-1. Furthermore, the emission cross section of the crystallized AC5 film was nearly 10(-16) cm2.

  8. Short communication: measurements of methane emissions from feed samples in filter bags or dispersed in the medium in an in vitro gas production system.

    Science.gov (United States)

    Ramin, M; Krizsan, S J; Jančík, F; Huhtanen, P

    2013-07-01

    The objective of this study was to compare methane (CH4) emissions from different feeds when incubated within filter bags for in vitro analysis or directly dispersed in the medium in an automated gas in vitro system. Four different concentrates and 4 forages were used in this study. Two lactating Swedish Red cows were used for the collection of rumen fluid. Feed samples were milled to pass a 1.0-mm screen. Aliquots (0.5 g) of samples were weighed directly in the bottles or within the F 0285 filter bags that were placed in the bottles. Gas samples were taken during 24 and 48 h of incubation, and CH4 concentration was determined. The data were analyzed using a general linear model. Feeds differed significantly in CH4 emission both at 24 and at 48 h of incubation. The interaction between feed and method on methane emission in vitro was significant, indicating that the ranking of feeds was not consistent between the methods. Generally, greater amounts of CH4 were emitted from samples directly dispersed in the medium compared with those incubated within the filter bags, which could be a result of lower microbial activity within the filter bags. The ratio of CH4 to total gas was greater when the feeds were incubated within bags compared with samples directly dispersed in the medium. Incubating samples in filter bags during 48 h of incubation cannot be recommended for determination of CH4 emission of feeds in vitro. Copyright © 2013 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

  9. Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs

    International Nuclear Information System (INIS)

    Luo Yongsong; Xia Xiaohong; Liang Ying; Zhang Yonggang; Ren Qinfeng; Li Jialin; Jia Zhijie; Tang Yiwen

    2007-01-01

    Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. - Graphical abstract: Luminescence of the short and ultrashort multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups, which is logically attributed to the trapping of excitation energy by defect sites, has been studied

  10. Bright Single InAsP Quantum Dots at Telecom Wavelengths in Position-Controlled InP Nanowires: The Role of the Photonic Waveguide.

    Science.gov (United States)

    Haffouz, Sofiane; Zeuner, Katharina D; Dalacu, Dan; Poole, Philip J; Lapointe, Jean; Poitras, Daniel; Mnaymneh, Khaled; Wu, Xiaohua; Couillard, Martin; Korkusinski, Marek; Schöll, Eva; Jöns, Klaus D; Zwiller, Valery; Williams, Robin L

    2018-05-09

    We report on the site-selected growth of bright single InAsP quantum dots embedded within InP photonic nanowire waveguides emitting at telecom wavelengths. We demonstrate a dramatic dependence of the emission rate on both the emission wavelength and the nanowire diameter. With an appropriately designed waveguide, tailored to the emission wavelength of the dot, an increase in the count rate by nearly 2 orders of magnitude (0.4 to 35 kcps) is obtained for quantum dots emitting in the telecom O-band, showing high single-photon purity with multiphoton emission probabilities down to 2%. Using emission-wavelength-optimized waveguides, we demonstrate bright, narrow-line-width emission from single InAsP quantum dots with an unprecedented tuning range of 880 to 1550 nm. These results pave the way toward efficient single-photon sources at telecom wavelengths using deterministically grown InAsP/InP nanowire quantum dots.

  11. Wavelength modulation spectroscopy of semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kohn, S.E.

    1977-10-01

    The use of modulation spectroscopy to study the electronic properties of solids has been very productive. The construction of a wide range Wavelength Modulation Spectrometer to study the optical properties of solids is described in detail. Extensions of the working range of the spectrometer into the vacuum ultraviolet are discussed. Measurements of the reflectivity and derivative reflectivity spectra of the lead chalcogenides, the chalcopyrite ZnGeP/sub 2/, the layer compounds GaSe and GaS and their alloys, the ferroelectric SbSI, layer compounds SnS/sub 2/ and SnSe/sub 2/, and HfS/sub 2/ were made. The results of these measurements are presented along with their interpretation in terms of band structure calculations.

  12. ISO observations of far-infrared rotational emission lines of water vapor toward the supergiant star VY Canis Majoris

    OpenAIRE

    Neufeld, David A.; Feuchtgruber, Helmut; Harwit, Martin; Melnick, Gary J.

    1999-01-01

    We report the detection of numerous far-infrared emission lines of water vapor toward the supergiant star VY Canis Majoris. A 29.5 - 45 micron grating scan of VY CMa, obtained using the Short Wavelength Spectrometer (SWS) of the Infrared Space Observatory (ISO) at a spectral resolving power of approximately 2000, reveals at least 41 spectral features due to water vapor that together radiate a total luminosity ~ 25 solar luminosities. In addition to pure rotational transitions within the groun...

  13. Ultra-violet emission in Ho:ZBLAN fiber

    International Nuclear Information System (INIS)

    Kowalska, M.; Klocek, G.; Piramidowicz, R.; Malinowski, M.

    2004-01-01

    We report on the short wavelength (green, blue, and ultra-violet (UV)) emission in trivalent holmium doped fluoro-zirconate fiber (Ho 3+ :ZBLAN) under direct and upconversion pumping. Efficient red to UV upconversion has been observed using 647 nm cw pumping by krypton ion laser. A close to cubic UV signal intensity dependence on incident red pump power was determined, confirming the three-photon character of the observed process. The responsible upconversion mechanisms were investigated and shown to be excited state absorption (ESA) via low-lying 5 I 7 and 5 I 6 sates. Dynamics of the involved excited states have been studied under pulsed laser excitation

  14. CO ICE PHOTODESORPTION: A WAVELENGTH-DEPENDENT STUDY

    International Nuclear Information System (INIS)

    Fayolle, Edith C.; Linnartz, Harold; Bertin, Mathieu; Romanzin, Claire; Michaut, Xavier; Fillion, Jean-Hugues; Oeberg, Karin I.

    2011-01-01

    UV-induced photodesorption of ice is a non-thermal evaporation process that can explain the presence of cold molecular gas in a range of interstellar regions. Information on the average UV photodesorption yield of astrophysically important ices exists for broadband UV lamp experiments. UV fields around low-mass pre-main-sequence stars, around shocks and in many other astrophysical environments are however often dominated by discrete atomic and molecular emission lines. It is therefore crucial to consider the wavelength dependence of photodesorption yields and mechanisms. In this work, for the first time, the wavelength-dependent photodesorption of pure CO ice is explored between 90 and 170 nm. The experiments are performed under ultra high vacuum conditions using tunable synchrotron radiation. Ice photodesorption is simultaneously probed by infrared absorption spectroscopy in reflection mode of the ice and by quadrupole mass spectrometry of the gas phase. The experimental results for CO reveal a strong wavelength dependence directly linked to the vibronic transition strengths of CO ice, implying that photodesorption is induced by electronic transition (DIET). The observed dependence on the ice absorption spectra implies relatively low photodesorption yields at 121.6 nm (Lyα), where CO barely absorbs, compared to the high yields found at wavelengths coinciding with transitions into the first electronic state of CO (A 1 Π at 150 nm); the CO photodesorption rates depend strongly on the UV profiles encountered in different star formation environments.

  15. Unveiling the Progenitors of Short-duration Gamma-ray Bursts

    Science.gov (United States)

    Fong, Wen-Fai

    2016-03-01

    Gamma-ray bursts (GRBs) are relativistic explosions which originate at cosmological distances, and are among the most luminous transients in the universe. Following the prompt gamma-ray emission, a fading synchrotron ``afterglow'' is detectable at lower energies. While long-duration GRBs (duration >2 sec) are linked to the deaths of massive stars, the progenitors of short-duration GRBs (duration black hole. Such merging systems are also important to understand because they are premier candidates for gravitational wave detections with current facilities and are likely sites of heavy element nucleosynthesis. The launch of NASA's Swift satellite in 2004, with its rapid multi-wavelength monitoring and localization capabilities, led to the first discoveries of short GRB afterglows and therefore robust associations to host galaxies. At a detection rate of roughly 10 events per year, the growing number of well-localized short GRBs has enabled comprehensive population studies of their afterglows and environments for the first time. In this talk, I describe my multi-wavelength observational campaign to address testable predictions for the progenitors of short GRBs. My work comprises several lines of independent evidence to demonstrate that short GRBs originate from the mergers of two compact objects, and also provides the first constraints on the explosion properties for a large sample of events. With the direct detection of gravitational waves from compact object mergers on the horizon, these studies provide necessary inputs to inform the next decade of joint electromagnetic-gravitational wave search strategies.

  16. Reliable Operation for 14500 h of a Wavelength-Stabilized Diode Laser System on a Microoptical Bench at 671 nm

    DEFF Research Database (Denmark)

    Sumpf, Bernd; Maiwald, Martin; Müller, André

    2012-01-01

    Reliability tests for wavelength-stabilized compact diode laser systems emitting at 671 nm are presented. The devices were mounted on microoptical benches with the dimensions of 13 mm $\\times\\,$4 mm. Reflecting Bragg gratings were used for wavelength stabilization and emission width narrowing...

  17. Usefulness of technetium-99m tetrofosmin single-photon emission computed tomography for short-term risk stratification in patients with acute chest pain in the emergency room

    International Nuclear Information System (INIS)

    Kawahito, Michitomo; Kondo, Makoto; Abe, Yoshiteru

    2003-01-01

    High-risk patients with acute coronary syndrome are difficult to distinguish from low-risk patients with chest pain in the emergency room. Technetium-99 m ( 99m Tc) tetrofosmin single-photon emission computed tomography (SPECT) was investigated to exclude high-risk patients with chest pain in the emergency room. 99m Tc-tetrofosmin SPECT was evaluated using a four-point scoring system in 228 patients (144 men, 84 women, mean age 68±12 years) with chest pain. Negative was defined as the myocardial segments with a defect score (DS) of 99m Tc-tetrofosmin; no significance (NS)), 84.9% (NS) and 60.4% (p 99m Tc-tetrofosmin SPECT is a useful method to exclude high-risk patients among patients with chest pain in the emergency room. (author)

  18. A look at some systemic properties of self-bioluminescent emission

    Science.gov (United States)

    Creath, Katherine

    2008-08-01

    Self-bioluminescent emission (SBE) is a type of biological chemiluminescence where photons are emitted as part of chemical reactions occurring during metabolic processes. This emission is also known as biophoton emission, ultraweak photon emission and ultraweak bioluminescence. This paper outlines research over the past century on some systemic properties of SBE as measured with biological detectors, photomultiplier detectors and ultra-sensitive imaging arrays. There is an apparent consensus in the literature that emission in the deep blue and ultraviolet (150-450nm) is related to DNA / RNA processes while emission in the red and near infrared (600-1000nm) is related to mitochondria and oxidative metabolisms involving reactive oxygen species, singlet oxygen and free radicals in plant, animal and human cells along with chlorophyll fluorescent decay in plants. Additionally, there are trends showing that healthy, unstressed and uninjured samples have less emission than samples that are unhealthy, stressed or injured. Mechanisms producing this emission can be narrowed down by isolating the wavelength region of interest and waiting for short-term fluorescence to decay leaving the ultraweak long-term metabolic emission. Examples of imaging this emission in healthy versus unhealthy, stressed versus unstressed, and injured versus uninjured plant parts are shown. Further discussion poses questions still to be answered related to properties such as coherence, photon statistics, and methodological means of isolating mechanisms.

  19. Effective wavelength calibration for moire fringe projection

    International Nuclear Information System (INIS)

    Purcell, Daryl; Davies, Angela; Farahi, Faramarz

    2006-01-01

    The fringe patterns seen when using moire instruments are similar to the patterns seen in traditional interferometry but differ in the spacing between consecutive fringes. In traditional interferometry, the spacing is constant and related to the wavelength of the source. In moire fringe projection, the spacing (the effective wavelength) may not be constant over the field of view and the spacing depends on the system geometry. In these cases, using a constant effective wavelength over the field of view causes inaccurate surface height measurements. We examine the calibration process of the moirefringe projection measurement, which takes this varying wavelength into account to produce a pixel-by-pixel wavelength map. The wavelength calibration procedure is to move the object in the out-of-plane direction a known distance until every pixel intensity value goes through at least one cycle. A sinusoidal function is then fit to the data to extract the effective wavelength pixel by pixel, yielding an effective wavelength map. A calibrated step height was used to validate the effective wavelength map with results within 1% of the nominal value of the step height. The error sources that contributed to the uncertainty in determining the height of the artifact are also investigated

  20. Short philtrum

    Science.gov (United States)

    ... this page: //medlineplus.gov/ency/article/003302.htm Short philtrum To use the sharing features on this page, please enable JavaScript. A short philtrum is a shorter than normal distance between ...

  1. The dynamics of interacting nonlinearities governing long wavelength driftwave turbulence

    International Nuclear Information System (INIS)

    Newman, D.E.

    1993-09-01

    Because of the ubiquitous nature of turbulence and the vast array of different systems which have turbulent solutions, the study of turbulence is an area of active research. Much present day understanding of turbulence is rooted in the well established properties of homogeneous Navier-Stokes turbulence, which, due to its relative simplicity, allows for approximate analytic solutions. This work examines a group of turbulent systems with marked differences from Navier-Stokes turbulence, and attempts to quantify some of their properties. This group of systems represents a variety of drift wave fluctuations believed to be of fundamental importance in laboratory fusion devices. From extensive simulation of simple local fluid models of long wavelength drift wave turbulence in tokamaks, a reasonably complete picture of the basic properties of spectral transfer and saturation has emerged. These studies indicate that many conventional notions concerning directions of cascades, locality and isotropy of transfer, frequencies of fluctuations, and stationarity of saturation are not valid for moderate to long wavelengths. In particular, spectral energy transfer at long wavelengths is dominated by the E x B nonlinearity, which carries energy to short scale in a manner that is highly nonlocal and anisotropic. In marked contrast to the canonical self-similar cascade dynamics of Kolmogorov, energy is efficiently passed between modes separated by the entire spectrum range in a correlation time. At short wavelengths, transfer is dominated by the polarization drift nonlinearity. While the standard dual cascade applies in this subrange, it is found that finite spectrum size can produce cascades that are reverse directed and are nonconservative in enstrophy and energy similarity ranges. In regions where both nonlinearities are important, cross-coupling between the nolinearities gives rise to large no frequency shifts as well as changes in the spectral dynamics

  2. Integrating spot short-term measurements of carbon emissions and backward dietary energy partition calculations to estimate intake in lactating dairy cows fed ad libitum or restricted.

    Science.gov (United States)

    Pereira, A B D; Utsumi, S A; Dorich, C D; Brito, A F

    2015-12-01

    The objective of this study was to use spot short-term measurements of CH4 (QCH4) and CO2 (QCO2) integrated with backward dietary energy partition calculations to estimate dry matter intake (DMI) in lactating dairy cows. Twelve multiparous cows averaging 173±37d in milk and 4 primiparous cows averaging 179±27d in milk were blocked by days in milk, parity, and DMI (as a percentage of body weight) and, within each block, randomly assigned to 1 of 2 treatments: ad libitum intake (AL) or restricted intake (RI=90% DMI) according to a crossover design. Each experimental period lasted 22d with 14d for treatments adaptation and 8d for data and sample collection. Diets contained (dry matter basis): 40% corn silage, 12% grass-legume haylage, and 48% concentrate. Spot short-term gas measurements were taken in 5-min sampling periods from 15 cows (1 cow refused sampling) using a portable, automated, open-circuit gas quantification system (GreenFeed, C-Lock Inc., Rapid City, SD) with intervals of 12h between the 2daily samples. Sampling points were advanced 2h from a day to the next to yield 16 gas samples per cow over 8d to account for diurnal variation in QCH4 and QCO2. The following equations were used sequentially to estimate DMI: (1) heat production (MJ/d)=(4.96 + 16.07 ÷ respiratory quotient) × QCO2; respiratory quotient=0.95; (2) metabolizable energy intake (MJ/d)=(heat production + milk energy) ± tissue energy balance; (3) digestible energy (DE) intake (MJ/d)=metabolizable energy + CH4 energy + urinary energy; (4) gross energy (GE) intake (MJ/d)=DE + [(DE ÷ in vitro true dry matter digestibility) - DE]; and (5) DMI (kg/d)=GE intake estimated ÷ diet GE concentration. Data were analyzed using the MIXED procedure of SAS (SAS Institute Inc., Cary, NC) and Fit Model procedure in JMP (α=0.05; SAS Institute Inc.). Cows significantly differed in DMI measured (23.8 vs. 22.4kg/d for AL and RI, respectively). Dry matter intake estimated using QCH4 and QCO2 coupled with

  3. On the generation of short-axis and radial long-axis slices in thallium-201 myocardial perfusion single-photon emission tomography

    International Nuclear Information System (INIS)

    Hastenberg, R.P.J.M. van; Eindhoven Univ. of Technology; Kemernik, G.J.; Hasman, A.

    1996-01-01

    We tried to develop fully automatic reorientation algorithms in thallium-201 myocardial perfusion single-photon emission tomography, and tested a method to evaluate the quality of reorientation. The left ventricle was automatically segmented using count density information, contours generated with Laplacian operators in both transaxial and sagittal slices, and morphological and positional characteristics of the contours. Reorientation was automatically performed based on knowledge of the long axis of a second degree surface fitted to the myocardial wall. We tried to achieve improvement in reorientation without relying on any functional description of left ventricular shape. Quality of reorientation was evaluated and improved using interactive tools in combination with radial long-axis slices. Two groups of 50 patients, after stress and rest, were analysed using the traditional manual and the fully automatic procedures. Automatic segmentation was successful in 98 out of 100 cases, and automatic reorientation was of reasonable quality. Reorientation obtained with the radial long-axis slices tool was better than after traditional manual or automatic reorientation. Automatic reorientation based on second degree surface fitting was in our hands less successful than reported in the literature. The tool using radial long-axis slices provides a better standard for testing reorientation algorithms than the traditional manual method. (orig.)

  4. Long-wavelength photonic integrated circuits and avalanche photodetectors

    Science.gov (United States)

    Tsou, Yi-Jen D.; Zaytsev, Sergey; Pauchard, Alexandre; Hummel, Steve; Lo, Yu-Hwa

    2001-10-01

    Fast-growing internet traffic volume require high data communication bandwidth over longer distances. Access network bottlenecks put pressure on short-range (SR) telecommunication systems. To effectively address these datacom and telecom market needs, low-cost, high-speed laser modules at 1310 to 1550 nm wavelengths and avalanche photodetectors are required. The great success of GaAs 850nm VCSEls for Gb/s Ethernet has motivated efforts to extend VCSEL technology to longer wavelengths in the 1310 and 1550 nm regimes. However, the technological challenges associated with materials for long wavelength VCSELs are tremendous. Even with recent advances in this area, it is believed that significant additional development is necessary before long wavelength VCSELs that meet commercial specifications will be widely available. In addition, the more stringent OC192 and OC768 specifications for single-mode fiber (SMF) datacom may require more than just a long wavelength laser diode, VCSEL or not, to address numerous cost and performance issues. We believe that photonic integrated circuits (PICs), which compactly integrate surface-emitting lasers with additional active and passive optical components with extended functionality, will provide the best solutions to today's problems. Photonic integrated circuits have been investigated for more than a decade. However, they have produced limited commercial impact to date primarily because the highly complicated fabrication processes produce significant yield and device performance issues. In this presentation, we will discuss a new technology platform of InP-based PICs compatible with surface-emitting laser technology, as well as a high data rate externally modulated laser module. Avalanche photodetectors (APDs) are the key component in the receiver to achieve high data rate over long transmission distance because of their high sensitivity and large gain- bandwidth product. We have used wafer fusion technology to achieve In

  5. The fabrication of millimeter-wavelength accelerating structures

    International Nuclear Information System (INIS)

    Chou, P.J.; Bowden, G.B.; Copeland, M.R.

    1996-11-01

    There is a growing interest in the development of high gradient (≥ 1 GeV/m) accelerating structures. The need for high gradient acceleration based on current microwave technology requires the structures to be operated in the millimeter wavelength. Fabrication of accelerating structures at millimeter scale with sub-micron tolerances poses great challenges. The accelerating structures impose strict requirements on surface smoothness and finish to suppress field emission and multipactor effects. Various fabrication techniques based on conventional machining and micromachining have been evaluated and tested. These will be discussed and measurement results presented

  6. An improved wavelength selection scheme for Monte Carlo solvers applied to hypersonic plasmas

    International Nuclear Information System (INIS)

    Feldick, Andrew; Modest, Michael F.

    2011-01-01

    A new databasing scheme is developed for Monte Carlo Ray Tracing methods applied to hypersonic planetary entry. In this scheme, the complex relationships for the emission wavelength selection of atomic and molecular species in nonequilibrium flows are simplified by developing random number relationships for individual transitions, as opposed to using relationships for the spectral emission coefficient of a given species. These new techniques speed up wavelength selection by about 2 orders of magnitude, and offer flexibility for use in weighted or part-spectrum Monte Carlo solvers.

  7. Positron emission tomography

    International Nuclear Information System (INIS)

    Iio, Masahiro

    1982-01-01

    Utilization of positron emission tomography was reviewed in relation to construction and planned construction of small-size medical cyclotrons, planned construction of positron cameras and utilization of short-lived radionuclides. (Chiba, N.)

  8. Wavelength scaling of laser plasma coupling

    International Nuclear Information System (INIS)

    Kruer, W.L.

    1983-01-01

    The use of shorter wavelength laser light both enhances collisional absorption and reduces deleterious collective plasma effects. Coupling processes which can be important in reactor-size targets are briefly reviewed. Simple estimates are presented for the intensity-wavelength regime in which collisional absorption is high and collective effects are minimized

  9. Inverse relationship between brain glucose and ketone metabolism in adults during short-term moderate dietary ketosis: A dual tracer quantitative positron emission tomography study.

    Science.gov (United States)

    Courchesne-Loyer, Alexandre; Croteau, Etienne; Castellano, Christian-Alexandre; St-Pierre, Valérie; Hennebelle, Marie; Cunnane, Stephen C

    2017-07-01

    Ketones (principally β-hydroxybutyrate and acetoacetate (AcAc)) are an important alternative fuel to glucose for the human brain, but their utilisation by the brain remains poorly understood. Our objective was to use positron emission tomography (PET) to assess the impact of diet-induced moderate ketosis on cerebral metabolic rate of acetoacetate (CMRa) and glucose (CMRglc) in healthy adults. Ten participants (35 ± 15 y) received a very high fat ketogenic diet (KD) (4.5:1; lipid:protein plus carbohydrates) for four days. CMRa and CMRglc were quantified by PET before and after the KD with the tracers, 11 C-AcAc and 18 F-fluorodeoxyglucose ( 18 F-FDG), respectively. During the KD, plasma ketones increased 8-fold ( p = 0.005) while plasma glucose decreased by 24% ( p = 0.005). CMRa increased 6-fold ( p = 0.005), whereas CMRglc decreased by 20% ( p = 0.014) on the KD. Plasma ketones were positively correlated with CMRa (r = 0.93; p < 0.0001). After four days on the KD, CMRa represented 17% of whole brain energy requirements in healthy adults with a 2-fold difference across brain regions (12-24%). The CMR of ketones (AcAc and β-hydroxybutyrate combined) while on the KD was estimated to represent about 33% of brain energy requirements or approximately double the CMRa. Whether increased ketone availability raises CMR of ketones to the same extent in older people as observed here or in conditions in which chronic brain glucose hypometabolism is present remains to be determined.

  10. Impact on short-lived climate forcers (SLCFs) from a realistic land-use change scenario via changes in biogenic emissions.

    Science.gov (United States)

    Scott, C E; Monks, S A; Spracklen, D V; Arnold, S R; Forster, P M; Rap, A; Carslaw, K S; Chipperfield, M P; Reddington, C L S; Wilson, C

    2017-08-24

    More than one quarter of natural forests have been cleared by humans to make way for other land-uses, with changes to forest cover projected to continue. The climate impact of land-use change (LUC) is dependent upon the relative strength of several biogeophysical and biogeochemical effects. In addition to affecting the surface albedo and exchanging carbon dioxide (CO 2 ) and moisture with the atmosphere, vegetation emits biogenic volatile organic compounds (BVOCs), altering the formation of short-lived climate forcers (SLCFs) including aerosol, ozone (O 3 ) and methane (CH 4 ). Once emitted, BVOCs are rapidly oxidised by O 3 , and the hydroxyl (OH) and nitrate (NO 3 ) radicals. These oxidation reactions yield secondary organic products which are implicated in the formation and growth of aerosol particles and are estimated to have a negative radiative effect on the climate (i.e. a cooling). These reactions also deplete OH, increasing the atmospheric lifetime of CH 4 , and directly affect concentrations of O 3 ; the latter two being greenhouse gases which impose a positive radiative effect (i.e. a warming) on the climate. Our previous work assessing idealised deforestation scenarios found a positive radiative effect due to changes in SLCFs; however, since the radiative effects associated with changes to SLCFs result from a combination of non-linear processes it may not be appropriate to scale radiative effects from complete deforestation scenarios according to the deforestation extent. Here we combine a land-surface model, a chemical transport model, a global aerosol model, and a radiative transfer model to assess the net radiative effect of changes in SLCFs due to historical LUC between the years 1850 and 2000.

  11. Influence of ablation wavelength and time on optical properties of laser ablated carbon dots

    Science.gov (United States)

    Isnaeni, Hanna, M. Yusrul; Pambudi, A. A.; Murdaka, F. H.

    2017-01-01

    Carbon dots, which are unique and applicable materials, have been produced using many techniques. In this work, we have fabricated carbon dots made of coconut fiber using laser ablation technique. The purpose of this work is to evaluate two ablation parameters, which are ablation wavelength and ablation time. We used pulsed laser from Nd:YAG laser with emit wavelength at 355 nm, 532 nm and 1064 nm. We varied ablation time one hour and two hours. Photoluminescence and time-resolved photoluminescence setup were used to study the optical properties of fabricated carbon dots. In general, fabricated carbon dots emit bluish green color emission upon excitation by blue laser. We found that carbon dots fabricated using 1064 nm laser produced the highest carbon dots emission among other samples. The peak wavelength of carbon dots emission is between 495 nm until 505 nm, which gives bluish green color emission. Two hours fabricated carbon dots gave four times higher emission than one hour fabricated carbon dot. More emission intensity of carbon dots means more carbon dots nanoparticles were fabricated during laser ablation process. In addition, we also measured electron dynamics of carbon dots using time-resolved photoluminescence. We found that sample with higher emission has longer electron decay time. Our finding gives optimum condition of carbon dots fabrication from coconut fiber using laser ablation technique. Moreover, fabricated carbon dots are non-toxic nanoparticles that can be applied for health, bio-tagging and medical applications.

  12. Shipping emissions in ports

    OpenAIRE

    Merk, Olaf

    2014-01-01

    Shipping emissions in ports are substantial, accounting for 18 million tonnes of CO2 emissions, 0.4 million tonnes of NOx, 0.2 million of SOx and 0.03 million tonnes of PM10 in 2011. Around 85% of emissions come from containerships and tankers. Containerships have short port stays, but high emissions during these stays. Most of CO2 emissions in ports from shipping are in Asia and Europe (58%), but this share is low compared to their share of port calls (70%). European ports have much less emi...

  13. Tunable Optical Tweezers for Wavelength-dependent Measurements

    Science.gov (United States)

    2012-04-23

    have been studied in an optical levitation scheme over short laser wavelength ranges20 and for dye-loaded di- electric particles.21 In the first case...M. Block, IEEE J. Sel. Top. Quantum Electron. 2, 1066 (1996). 7K. Dholakia, W. M. Lee, L. Paterson, M. P. MacDonald, I. Andreev, P. Mthunzi, C. T. A...Brown, R. F. Marchington, and A. C. Riches, IEEE J. Sel. Top. Quantum Electron. 13, 1646 (2007). 8K. Dholakia, M. P. MacDonald, P. Zemanek, and T

  14. Eddy covariance flux measurements confirm extreme CH4 emissions from a Swiss hydropower reservoir and resolve their short-term variability

    Directory of Open Access Journals (Sweden)

    S. Sobek

    2011-09-01

    Full Text Available Greenhouse gas budgets quantified via land-surface eddy covariance (EC flux sites differ significantly from those obtained via inverse modeling. A possible reason for the discrepancy between methods may be our gap in quantitative knowledge of methane (CH4 fluxes. In this study we carried out EC flux measurements during two intensive campaigns in summer 2008 to quantify methane flux from a hydropower reservoir and link its temporal variability to environmental driving forces: water temperature and pressure changes (atmospheric and due to changes in lake level. Methane fluxes were extremely high and highly variable, but consistently showed gas efflux from the lake when the wind was approaching the EC sensors across the open water, as confirmed by floating chamber flux measurements. The average flux was 3.8 ± 0.4 μg C m−2 s−1 (mean ± SE with a median of 1.4 μg C m−2 s−1, which is quite high even compared to tropical reservoirs. Floating chamber fluxes from four selected days confirmed such high fluxes with 7.4 ± 1.3 μg C m−2 s−1. Fluxes increased exponentially with increasing temperatures, but were decreasing exponentially with increasing atmospheric and/or lake level pressure. A multiple regression using lake surface temperatures (0.1 m depth, temperature at depth (10 m deep in front of the dam, atmospheric pressure, and lake level was able to explain 35.4% of the overall variance. This best fit included each variable averaged over a 9-h moving window, plus the respective short-term residuals thereof. We estimate that an annual average of 3% of the particulate organic matter (POM input via the river is sufficient to sustain these large CH4 fluxes. To compensate the global warming potential associated with the CH4 effluxes from this hydropower reservoir a 1.3 to 3.7 times larger terrestrial area with net carbon dioxide uptake is needed if a European-scale compilation of grasslands, croplands and forests is taken as reference. This

  15. Significance of a notch in the otoacoustic emission stimulus spectrum.

    Science.gov (United States)

    Grenner, J

    2012-09-01

    To explain a clinical observation: a notch in the stimulus spectrum during transient evoked otoacoustic emission measurement in ears with secretory otitis media. The effects of tympanic under-pressure were investigated using a pressure chamber. A model of the ear canal was also studied. Tympanic membrane reflectance increased as a consequence of increased stiffness, causing a notch in the stimulus spectrum. In an adult, the notch could be clearly distinguished at an under-pressure of approximately -185 daPa. The sound frequency of the notch corresponded to a wavelength four times the ear canal length. The ear canal of infants was too short to cause a notch within the displayed frequency range. The notch was demonstrated using both Otodynamics and Madsen equipment. A notch in the otoacoustic emission stimulus spectrum can be caused by increased stiffness of the tympanic membrane, raising suspicion of low middle-ear pressure or secretory otitis media. This finding is not applicable to infants.

  16. The large scale infrared emission in the galactic plane - observations

    International Nuclear Information System (INIS)

    Okuda, H.

    1981-01-01

    Infrared radiation is deeply involved in a variety of matters and processes in the galaxy. Near infrared radiation is predominantly emitted by late type stars which include the major part of the mass in the Galaxy and hence govern its dynamics. Short wavelength radiation (UV and visible) emitted from early type stars is easily absorbed by dust around the stars themselves or by interstellar dust, and reemitted in middle or far infrared regions. A variety of emission lines, fine structure lines of neutral and ionized heavy elements, as well as many molecular lines are also clustered in the middle and far infrared regions. Since their line intensities are generally very weak, and, moreover, spectroscopic observations demand relatively difficult techniques in their detection, the surveys so far done have been limited mostly to continuum emission. This article compiles them and discusses briefly their implications to the structure of the Galaxy in its inner region. (Auth.)

  17. Simultaneous, multi-wavelength flare observations of nearby low-mass stars

    Science.gov (United States)

    Thackeray, Beverly; Barclay, Thomas; Quintana, Elisa; Villadsen, Jacqueline; Wofford, Alia; Schlieder, Joshua; Boyd, Patricia

    2018-01-01

    Low-mass stars are the most common stars in the Galaxy and have been targeted in the tens-of-thousands by K2, the re-purposed Kepler mission, as they are prime targets to search for and characterize small, Earth-like planets. Understanding how these fully convective stars drive magnetic activity that manifests as stochastic, short-term brightenings, or flares, provides insight into the prospects of planetary habitability. High energy radiation and energetic particle emission associated with these stars can erode atmospheres, and impact habitability. An innovative campaign to study low mass stars through simultaneous multi-wavelength observations is currently underway with observations ongoing in the X-ray, UV, optical, and radio. I will present early results of our pilot study of the nearby M-Dwarf star Wolf 359 (CN Leo) using K2, SWIFT, and ground based radio observatories, forming a comprehensive picture of flare activity from an M-Dwarf, and discuss the potential impact of these results on exoplanets. "This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant No. DGE1322106. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation."

  18. Effective long wavelength scalar dynamics in de Sitter

    Energy Technology Data Exchange (ETDEWEB)

    Moss, Ian; Rigopoulos, Gerasimos, E-mail: ian.moss@newcastle.ac.uk, E-mail: gerasimos.rigopoulos@ncl.ac.uk [School of Mathematics and Statistics, Newcastle University, Herschel Building, Newcastle upon Tyne, NE1 7RU U.K. (United Kingdom)

    2017-05-01

    We discuss the effective infrared theory governing a light scalar's long wavelength dynamics in de Sitter spacetime. We show how the separation of scales around the physical curvature radius k / a ∼ H can be performed consistently with a window function and how short wavelengths can be integrated out in the Schwinger-Keldysh path integral formalism. At leading order, and for time scales Δ t >> H {sup −1}, this results in the well-known Starobinsky stochastic evolution. However, our approach allows for the computation of quantum UV corrections, generating an effective potential on which the stochastic dynamics takes place. The long wavelength stochastic dynamical equations are now second order in time, incorporating temporal scales Δ t ∼ H {sup −1} and resulting in a Kramers equation for the probability distribution—more precisely the Wigner function—in contrast to the more usual Fokker-Planck equation. This feature allows us to non-perturbatively evaluate, within the stochastic formalism, not only expectation values of field correlators, but also the stress-energy tensor of φ.

  19. First Resolved Images of the Mira AB Symbiotic Binary at Centimeter Wavelengths

    OpenAIRE

    Matthews, Lynn D.; Karovska, Margarita

    2005-01-01

    We report the first spatially resolved radio continuum measurements of the Mira AB symbiotic binary system, based on observations obtained with the Very Large Array (VLA). This is the first time that a symbiotic binary has been resolved unambiguously at centimeter wavelengths. We describe the results of VLA monitoring of both stars over a ten month period, together with constraints on their individual spectral energy distributions, variability, and radio emission mechanisms. The emission from...

  20. Multi-wavelength lasers using AWGs

    NARCIS (Netherlands)

    Besten, den J.H.

    2003-01-01

    Multiwavelength lasers using AWGs can be used as digitally tunable lasers with simple channel selection, and for generating multiple wavelengths simultanously. In this paper a number of different configurations is reviewed.

  1. Wavelength-tunable colloidal quantum dot laser on ultra-thin flexible glass

    Energy Technology Data Exchange (ETDEWEB)

    Foucher, C.; Guilhabert, B.; Laurand, N.; Dawson, M. D. [Institute of Photonics, SUPA, University of Strathclyde, Glasgow (United Kingdom)

    2014-04-07

    A mechanically flexible and wavelength-tunable laser with an ultra-thin glass membrane as substrate is demonstrated. The optically pumped hybrid device has a distributed feedback cavity that combines a colloidal quantum dot gain film with a grating-patterned polymeric underlayer, all on a 30-μm thick glass sheet. The total thickness of the structure is only 75 μm. The hybrid laser has an average threshold fluence of 450 ± 80 μJ/cm{sup 2} (for 5-ns excitation pulses) at an emitting wavelength of 607 nm. Mechanically bending the thin-glass substrate enables continuous tuning of the laser emission wavelength over an 18-nm range, from 600 nm to 618 nm. The correlation between the wavelength tunability and the mechanical properties of the thin laser structure is verified theoretically and experimentally.

  2. Wavelength interrogation of fiber Bragg grating sensors using tapered hollow Bragg waveguides.

    Science.gov (United States)

    Potts, C; Allen, T W; Azar, A; Melnyk, A; Dennison, C R; DeCorby, R G

    2014-10-15

    We describe an integrated system for wavelength interrogation, which uses tapered hollow Bragg waveguides coupled to an image sensor. Spectral shifts are extracted from the wavelength dependence of the light radiated at mode cutoff. Wavelength shifts as small as ~10  pm were resolved by employing a simple peak detection algorithm. Si/SiO₂-based cladding mirrors enable a potential operational range of several hundred nanometers in the 1550 nm wavelength region for a taper length of ~1  mm. Interrogation of a strain-tuned grating was accomplished using a broadband amplified spontaneous emission (ASE) source, and potential for single-chip interrogation of multiplexed sensor arrays is demonstrated.

  3. Emission spectrum and relaxation kinetics of SO2 induced by 266 nm laser.

    Science.gov (United States)

    Zhang, Guiyin; Zhang, Lianshui; Jin, Yidong

    2010-09-15

    Laser induced fluorescence (LIF) emission spectrum of SO(2) in the range of 270.0-470.0 nm has been obtained with the quadruple harmonic output (266 nm) of a pulsed Nd:YAG laser as excitation source. The spectrum is composed of a continuous envelope in the short wavelength side, while it shows the character of banded structure superimposed on a continuous one in the long wavelength region. Fluorescence emission from the hybrid states of A(1)A(2)+B(1)B(1) and X(1)A(1)+B(1)B(1) forms the continuous envelope and phosphorescence emission from the triplet state a(3)B(1) forms the banded progression. It is also found that direct emission from laser excited states is very weak. The primary portion of the emission is from the energy levels populated by collision relaxation or collision induced intersystem crossing process. The harmonic frequencies and inharmonic coefficients of the symmetric stretching vibration and the bending vibration of X(1)A(1) state are derived from the ascription of the phosphorescence progression. Copyright 2010 Elsevier B.V. All rights reserved.

  4. Wavelength mismatch effect in electromagnetically induced absorption

    Energy Technology Data Exchange (ETDEWEB)

    Bharti, Vineet [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Wasan, Ajay [Department of Physics, Indian Institute of Technology, Roorkee 247667 (India); Natarajan, Vasant [Department of Physics, Indian Institute of Science, Bangalore 560012 (India)

    2016-07-15

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  5. Wavelength mismatch effect in electromagnetically induced absorption

    International Nuclear Information System (INIS)

    Bharti, Vineet; Wasan, Ajay; Natarajan, Vasant

    2016-01-01

    We present a theoretical investigation of the phenomenon of electromagnetically induced absorption (EIA) in a 4-level system consisting of vee and ladder subsystems. The four levels are coupled using one weak probe field, and two strong control fields. We consider an experimental realization using energy levels of Rb. This necessitates dealing with different conditions of wavelength mismatch—near-perfect match where all three wavelengths are approximately equal; partial mismatch where the wavelength of one control field is less than the other fields; and complete mismatch where all three wavelengths are unequal. We present probe absorption profiles with Doppler averaging at room temperature to account for experiments in a room temperature Rb vapor cell. Our analysis shows that EIA resonances can be studied using Rydberg states excited with diode lasers. - Highlights: • Wavelength mismatch effect is investigated in electromagnetically induced absorption (EIA). • An experimental realization of 4-level vee + ladder system using energy levels of rubidium atom is presented. • EIA resonances are studied under different conditions of wavelength mismatch. • Possibility of observation of EIA using Rydberg states excited with diode lasers.

  6. X-ray emission reduction and photon dose lowering by energy loss of fast electrons induced by return current during the interaction of a short-pulse high-intensity laser on a metal solid target

    Science.gov (United States)

    Compant La Fontaine, A.

    2018-04-01

    During the interaction of a short-pulse high-intensity laser with the preplasma produced by the pulse's pedestal in front of a high-Z metal solid target, high-energy electrons are produced, which in turn create an X-ray source by interacting with the atoms of the converter target. The current brought by the hot electrons is almost completely neutralized by a return current j → driven by the background electrons of the conductive target, and the force exerted on the hot electrons by the electric field E → which induces Ohmic heating j → .E → , produced by the background electrons, reduces the energy of the hot electrons and thus lowers the X-ray emission and photon dose. This effect is analyzed here by means of a simple 1-D temperature model which contains the most significant terms of the relativistic Fokker-Planck equation with electron multiple scattering, and the energy equations of ions, hot, and cold electrons are then solved numerically. This Ohmic heating energy loss fraction τOh is introduced as a corrective term in an improved photon dose model. For instance, for a ps laser pulse with 10 μm spot size, the dose obtained with a tantalum target is reduced by less than about 10% to 40% by the Ohmic heating, depending upon the plasma scale length, target thickness, laser parameters, and in particular its spot size. The laser and plasma parameters may be optimized to limit the effect of Ohmic heating, for instance at a small plasma scale length or small laser spot size. Conversely, others regimes not suitable for dose production are identified. For instance, the resistive heating is enhanced in a foam target or at a long plasma scale length and high laser spot size and intensity, as the mean emission angle θ0 of the incident hot electron bunch given by the ponderomotive force is small; thus, the dose produced by a laser interacting in a gas jet may be inhibited under these circumstances. The resistive heating may also be maximized in order to reduce

  7. An organic white light-emitting dye: very small molecular architecture displays panchromatic emission.

    Science.gov (United States)

    Nandhikonda, Premchendar; Heagy, Michael D

    2010-11-14

    The synthesis and photophysical characterization of a new white-light fluorophore is described. The optimization of excitation wavelengths allows the naphthalimide (NI) dyes to display blue, green or white light emission depending on the excitation wavelength.

  8. A multi-model intercomparison of halogenated very short-lived substances (TransCom-VSLS: linking oceanic emissions and tropospheric transport for a reconciled estimate of the stratospheric source gas injection of bromine

    Directory of Open Access Journals (Sweden)

    R. Hossaini

    2016-07-01

    Full Text Available The first concerted multi-model intercomparison of halogenated very short-lived substances (VSLS has been performed, within the framework of the ongoing Atmospheric Tracer Transport Model Intercomparison Project (TransCom. Eleven global models or model variants participated (nine chemical transport models and two chemistry–climate models by simulating the major natural bromine VSLS, bromoform (CHBr3 and dibromomethane (CH2Br2, over a 20-year period (1993–2012. Except for three model simulations, all others were driven offline by (or nudged to reanalysed meteorology. The overarching goal of TransCom-VSLS was to provide a reconciled model estimate of the stratospheric source gas injection (SGI of bromine from these gases, to constrain the current measurement-derived range, and to investigate inter-model differences due to emissions and transport processes. Models ran with standardised idealised chemistry, to isolate differences due to transport, and we investigated the sensitivity of results to a range of VSLS emission inventories. Models were tested in their ability to reproduce the observed seasonal and spatial distribution of VSLS at the surface, using measurements from NOAA's long-term global monitoring network, and in the tropical troposphere, using recent aircraft measurements – including high-altitude observations from the NASA Global Hawk platform. The models generally capture the observed seasonal cycle of surface CHBr3 and CH2Br2 well, with a strong model–measurement correlation (r  ≥  0.7 at most sites. In a given model, the absolute model–measurement agreement at the surface is highly sensitive to the choice of emissions. Large inter-model differences are apparent when using the same emission inventory, highlighting the challenges faced in evaluating such inventories at the global scale. Across the ensemble, most consistency is found within the tropics where most of the models (8 out of 11 achieve best agreement to

  9. Field-emission from quantum-dot-in-perovskite solids.

    Science.gov (United States)

    García de Arquer, F Pelayo; Gong, Xiwen; Sabatini, Randy P; Liu, Min; Kim, Gi-Hwan; Sutherland, Brandon R; Voznyy, Oleksandr; Xu, Jixian; Pang, Yuangjie; Hoogland, Sjoerd; Sinton, David; Sargent, Edward

    2017-03-24

    Quantum dot and well architectures are attractive for infrared optoelectronics, and have led to the realization of compelling light sensors. However, they require well-defined passivated interfaces and rapid charge transport, and this has restricted their efficient implementation to costly vacuum-epitaxially grown semiconductors. Here we report solution-processed, sensitive infrared field-emission photodetectors. Using quantum-dots-in-perovskite, we demonstrate the extraction of photocarriers via field emission, followed by the recirculation of photogenerated carriers. We use in operando ultrafast transient spectroscopy to sense bias-dependent photoemission and recapture in field-emission devices. The resultant photodiodes exploit the superior electronic transport properties of organometal halide perovskites, the quantum-size-tuned absorption of the colloidal quantum dots and their matched interface. These field-emission quantum-dot-in-perovskite photodiodes extend the perovskite response into the short-wavelength infrared and achieve measured specific detectivities that exceed 10 12 Jones. The results pave the way towards novel functional photonic devices with applications in photovoltaics and light emission.

  10. A search for radio emission from exoplanets around evolved stars

    Science.gov (United States)

    O'Gorman, E.; Coughlan, C. P.; Vlemmings, W.; Varenius, E.; Sirothia, S.; Ray, T. P.; Olofsson, H.

    2018-04-01

    The majority of searches for radio emission from exoplanets have to date focused on short period planets, i.e., the so-called hot Jupiter type planets. However, these planets are likely to be tidally locked to their host stars and may not generate sufficiently strong magnetic fields to emit electron cyclotron maser emission at the low frequencies used in observations (typically ≥150 MHz). In comparison, the large mass-loss rates of evolved stars could enable exoplanets at larger orbital distances to emit detectable radio emission. Here, we first show that the large ionized mass-loss rates of certain evolved stars relative to the solar value could make them detectable with the LOw Frequency ARray (LOFAR) at 150 MHz (λ = 2 m), provided they have surface magnetic field strengths >50 G. We then report radio observations of three long period (>1 au) planets that orbit the evolved stars β Gem, ι Dra, and β UMi using LOFAR at 150 MHz. We do not detect radio emission from any system but place tight 3σ upper limits of 0.98, 0.87, and 0.57 mJy on the flux density at 150 MHz for β Gem, ι Dra, and β UMi, respectively. Despite our non-detections these stringent upper limits highlight the potential of LOFAR as a tool to search for exoplanetary radio emission at meter wavelengths.

  11. A 12 GHz wavelength spacing multi-wavelength laser source for wireless communication systems

    Science.gov (United States)

    Peng, P. C.; Shiu, R. K.; Bitew, M. A.; Chang, T. L.; Lai, C. H.; Junior, J. I.

    2017-08-01

    This paper presents a multi-wavelength laser source with 12 GHz wavelength spacing based on a single distributed feedback laser. A light wave generated from the distributed feedback laser is fed into a frequency shifter loop consisting of 50:50 coupler, dual-parallel Mach-Zehnder modulator, optical amplifier, optical filter, and polarization controller. The frequency of the input wavelength is shifted and then re-injected into the frequency shifter loop. By re-injecting the shifted wavelengths multiple times, we have generated 84 optical carriers with 12 GHz wavelength spacing and stable output power. For each channel, two wavelengths are modulated by a wireless data using the phase modulator and transmitted through a 25 km single mode fiber. In contrast to previously developed schemes, the proposed laser source does not incur DC bias drift problem. Moreover, it is a good candidate for radio-over-fiber systems to support multiple users using a single distributed feedback laser.

  12. Wavelength converter placement for different RWA algorithms in wavelength-routed all-optical networks

    Science.gov (United States)

    Chu, Xiaowen; Li, Bo; Chlamtac, Imrich

    2002-07-01

    Sparse wavelength conversion and appropriate routing and wavelength assignment (RWA) algorithms are the two key factors in improving the blocking performance in wavelength-routed all-optical networks. It has been shown that the optimal placement of a limited number of wavelength converters in an arbitrary mesh network is an NP complete problem. There have been various heuristic algorithms proposed in the literature, in which most of them assume that a static routing and random wavelength assignment RWA algorithm is employed. However, the existing work shows that fixed-alternate routing and dynamic routing RWA algorithms can achieve much better blocking performance. Our study in this paper further demonstrates that the wavelength converter placement and RWA algorithms are closely related in the sense that a well designed wavelength converter placement mechanism for a particular RWA algorithm might not work well with a different RWA algorithm. Therefore, the wavelength converter placement and the RWA have to be considered jointly. The objective of this paper is to investigate the wavelength converter placement problem under fixed-alternate routing algorithm and least-loaded routing algorithm. Under the fixed-alternate routing algorithm, we propose a heuristic algorithm called Minimum Blocking Probability First (MBPF) algorithm for wavelength converter placement. Under the least-loaded routing algorithm, we propose a heuristic converter placement algorithm called Weighted Maximum Segment Length (WMSL) algorithm. The objective of the converter placement algorithm is to minimize the overall blocking probability. Extensive simulation studies have been carried out over three typical mesh networks, including the 14-node NSFNET, 19-node EON and 38-node CTNET. We observe that the proposed algorithms not only outperform existing wavelength converter placement algorithms by a large margin, but they also can achieve almost the same performance comparing with full wavelength

  13. Ultraviolet continuum and H2 fluorescent emission in Herbig-Haro objects 43 and 47

    International Nuclear Information System (INIS)

    Schwartz, R.D.

    1983-01-01

    The results of International Ultraviolet Explorer (IUE) short-wavelength spectra of the low-excitation Herbig-Haro objects HH 43 and HH 47 are reported. In HH 43 a number of emission lines in the Lyman band of H 2 from the excited state 1 μ + /sub u/, #betta#' = 1, J' = 4 are observed. The lines are produced by fluorescence from the H Lyα line which pumps the lower state 1 μ + /sub g/, #betta#'' = 2.J'' = 5 which in turn is excited by a low-velocity shock wave. No evidence of emission from highly ionized gas is present in the UV spectra. Both objects exhibit a UV continuum which peaks in the vicinity of 1500 A and which is probably caused by hydrogen two-photon emission enhanced by collisional excitation in a low-velocity shock

  14. Short communication

    African Journals Online (AJOL)

    abp

    2017-09-04

    Sep 4, 2017 ... Face-to-face interviews were conducted using a standardized ... Short communication. Open Access ... clinic during the time of the study and were invited to participate in the study. .... consume them. This is another ...

  15. SHORT COMMUNICATION

    African Journals Online (AJOL)

    PROF P.T. KAYE

    . SHORT COMMUNICATION. Formation and Structural Analysis of Novel Dibornyl Ethers. Perry T. Kaye*, Andrew R. Duggan, Joseph M. Matjila, Warner E. Molema, and. Swarnam S. Ravindran. Department of Chemistry, Rhodes University, Grahamstown, ...

  16. DNA abasic site-selective enhancement of sanguinarine fluorescence with a large emission shift.

    Directory of Open Access Journals (Sweden)

    Fei Wu

    Full Text Available Small molecules that can specifically bind to a DNA abasic site (AP site have received much attention due to their importance in DNA lesion identification, drug discovery, and sensor design. Herein, the AP site binding behavior of sanguinarine (SG, a natural alkaloid, was investigated. In aqueous solution, SG has a short-wavelength alkanolamine emission band and a long-wavelength iminium emission band. At pH 8.3, SG experiences a fluorescence quenching for both bands upon binding to fully matched DNAs without the AP site, while the presence of the AP site induces a strong SG binding and the observed fluorescence enhancement for the iminium band are highly dependent on the nucleobases flanking the AP site, while the alkanolamine band is always quenched. The bases opposite the AP site also exert some modifications on the SG's emission behavior. It was found that the observed quenching for DNAs with Gs and Cs flanking the AP site is most likely caused by electron transfer between the AP site-bound excited-state SG and the nearby Gs. However, the flanking As and Ts that are not easily oxidized favor the enhanced emission. This AP site-selective enhancement of SG fluorescence accompanies a band conversion in the dominate emission from the alkanolamine to iminium band thus with a large emission shift of about 170 nm. Absorption spectra, steady-state and transient-state fluorescence, DNA melting, and electrolyte experiments confirm that the AP site binding of SG occurs and the stacking interaction with the nearby base pairs is likely to prevent the converted SG iminium form from contacting with water that is thus emissive when the AP site neighbors are bases other than guanines. We expect that this fluorophore would be developed as a promising AP site binder having a large emission shift.

  17. Wavelength division multiplexing a practical engineering guide

    CERN Document Server

    Grobe, Klaus

    2013-01-01

    In this book, Optical Wavelength Division Multiplexing (WDM) is approached from a strictly practical and application-oriented point of view. Based on the characteristics and constraints of modern fiber-optic components, transport systems and fibers, the text provides relevant rules of thumb and practical hints for technology selection, WDM system and link dimensioning, and also for network-related aspects such as wavelength assignment and resilience mechanisms. Actual 10/40 Gb/s WDM systems are considered, and a preview of the upcoming 100 Gb/s systems and technologies for even higher bit rate

  18. Wavelength dependence of superhumps in VW Hyi

    International Nuclear Information System (INIS)

    Amerongen, S. van; Bovenschen, H.; Paradijs, J. van

    1987-01-01

    Results are presented of five-colour photometric observations of the SU UMa system VW Hyi, made on six nights during the November 1984 superoutburst. The light curve is dominated by superhump variations, whose amplitude in all passbands decreases with time (in the V-band from 0.16 mag about 4.5 day after the superoutburst reached maximum brightness, to 0.10 mag about 5 day later). The superhump light curve depends strongly on wavelength. In particular it appears that the light curves in different passbands are mutually shifted: the larger the wavelength, the more the light curve is delayed. (author)

  19. Brightness temperature of the ''quiet'' Sun in the millimeter wavelength range

    International Nuclear Information System (INIS)

    Pelyushenko, S.A.

    1982-01-01

    Results are presented of recalibration of the data available for measurements of the solar brightness temperature Tsub(s) made by comparison with the lunar radio emission. A spectrum has been obtained of the ''quiet'' Sun radio emission in the range of 1-20 mm. The mean square spread of data does not exceed +-(from 3 to 4)%. The ''quiet'' Sun spectrum has a form of: Tsub(c)=(6150+-70)lambdasup(01+-0.01)[mm]K in the wavelength interval of lambda=(1-6) mm and Tsub(c)=(3470+-80)lambdasup(0.42+-0.01) [mm]K in the wavelength interval of lambda=(7-20) mm on approximation of recalibrated values of Tsub(c) with a linear dependence using the mean-square-root method. The obtained spectral characteristics of the ''quiet'' Sun radio frequency emission in the mullimeter wavelength range testify on the spectrum flatteming in the (1-6) mm wavelength range

  20. Solar Prominence Modelling and Plasma Diagnostics at ALMA Wavelengths

    Science.gov (United States)

    Rodger, Andrew; Labrosse, Nicolas

    2017-09-01

    Our aim is to test potential solar prominence plasma diagnostics as obtained with the new solar capability of the Atacama Large Millimeter/submillimeter Array (ALMA). We investigate the thermal and plasma diagnostic potential of ALMA for solar prominences through the computation of brightness temperatures at ALMA wavelengths. The brightness temperature, for a chosen line of sight, is calculated using the densities of electrons, hydrogen, and helium obtained from a radiative transfer code under non-local thermodynamic equilibrium (non-LTE) conditions, as well as the input internal parameters of the prominence model in consideration. Two distinct sets of prominence models were used: isothermal-isobaric fine-structure threads, and large-scale structures with radially increasing temperature distributions representing the prominence-to-corona transition region. We compute brightness temperatures over the range of wavelengths in which ALMA is capable of observing (0.32 - 9.6 mm), however, we particularly focus on the bands available to solar observers in ALMA cycles 4 and 5, namely 2.6 - 3.6 mm (Band 3) and 1.1 - 1.4 mm (Band 6). We show how the computed brightness temperatures and optical thicknesses in our models vary with the plasma parameters (temperature and pressure) and the wavelength of observation. We then study how ALMA observables such as the ratio of brightness temperatures at two frequencies can be used to estimate the optical thickness and the emission measure for isothermal and non-isothermal prominences. From this study we conclude that for both sets of models, ALMA presents a strong thermal diagnostic capability, provided that the interpretation of observations is supported by the use of non-LTE simulation results.

  1. Short Stature

    DEFF Research Database (Denmark)

    Christesen, Henrik Boye Thybo; Pedersen, Birgitte Tønnes; Pournara, Effie

    2016-01-01

    -scale, non-interventional, multinational study. The patient cohort consisted of 5996 short pediatric patients diagnosed with growth hormone deficiency (GHD), Turner syndrome (TS) or born small for gestational age (SGA). The proportions of children with baseline height standard deviation score (SDS) below......The use of appropriate growth standards/references is of significant clinical importance in assessing the height of children with short stature as it may determine eligibility for appropriate therapy. The aim of this study was to determine the impact of using World Health Organization (WHO) instead...... of national growth standards/references on height assessment in short children. Data were collected from routine clinical practice (1998-2014) from nine European countries that have available national growth references and were enrolled in NordiNet® International Outcome Study (IOS) (NCT00960128), a large...

  2. Energy Levels, wavelengths and hyperfine structure measurements of Sc II

    Science.gov (United States)

    Hala, Fnu; Nave, Gillian

    2018-01-01

    Lines of singly ionized Scandium (Sc II) along with other Iron group elements have been observed [1] in the region surrounding the massive star Eta Carinae [2,3] called the strontium filament (SrF). The last extensive analysis of Sc II was the four-decade old work of Johansson & Litzen [4], using low-resolution grating spectroscopy. To update and extend the Sc II spectra, we have made observation of Sc/Ar, Sc/Ne and Sc/Ge/Ar hollow cathode emission spectrum on the NIST high resolution FT700 UV/Vis and 2 m UV/Vis/IR Fourier transform spectrometers (FTS). More than 850 Sc II lines have been measured in the wavelength range of 187 nm to 3.2 μm. connecting a total of 152 energy levels. The present work also focuses to resolve hyperfine structure (HFS) in Sc II lines. We aim to obtain accurate transition wavelengths, improved energy levels and HFS constants of Sc II. The latest results from work in progress will be presented.Reference[1] Hartman H, Gull T, Johansson S and Smith N 2004 Astron. Astrophys. 419 215[2] Smith N, Morse J A and Gull T R 2004 Astrophys. J. 605 405[3] Davidson K and Humphreys R M 1997 Annu. Rev. Astron. Astrophys. 35[4] Johansson S and Litzén U 1980 Phys. Scr. 22 49

  3. Multi-client quantum key distribution using wavelength division multiplexing

    International Nuclear Information System (INIS)

    Grice, Warren P.; Bennink, Ryan S.; Earl, Dennis Duncan; Evans, Philip G.; Humble, Travis S.; Pooser, Raphael C.; Schaake, Jason; Williams, Brian P.

    2011-01-01

    Quantum Key Distribution (QKD) exploits the rules of quantum mechanics to generate and securely distribute a random sequence of bits to two spatially separated clients. Typically a QKD system can support only a single pair of clients at a time, and so a separate quantum link is required for every pair of users. We overcome this limitation with the design and characterization of a multi-client entangled-photon QKD system with the capacity for up to 100 clients simultaneously. The time-bin entangled QKD system includes a broadband down-conversion source with two unique features that enable the multi-user capability. First, the photons are emitted across a very large portion of the telecom spectrum. Second, and more importantly, the photons are strongly correlated in their energy degree of freedom. Using standard wavelength division multiplexing (WDM) hardware, the photons can be routed to different parties on a quantum communication network, while the strong spectral correlations ensure that each client is linked only to the client receiving the conjugate wavelength. In this way, a single down-conversion source can support dozens of channels simultaneously--and to the extent that the WDM hardware can send different spectral channels to different clients, the system can support multiple client pairings. We will describe the design and characterization of the down-conversion source, as well as the client stations, which must be tunable across the emission spectrum.

  4. Single-photon generator for optical telecommunication wavelength

    International Nuclear Information System (INIS)

    Usuki, T; Sakuma, Y; Hirose, S; Takemoto, K; Yokoyama, N; Miyazawa, T; Takatsu, M; Arakawa, Y

    2006-01-01

    We report on the generation of single-photon pulses from a single InAs/InP quantum dot in telecommunication bands (1.3-1.55 μm: higher transmittance through an optical fiber). First we prepared InAs quantum dots on InP (0 0 1) substrates in a low-pressure MOCVD by using a so-called InP 'double-cap' procedure. The quantum dots have well-controlled photo emission wavelength in the telecommunication bands. We also developed a single-photon emitter in which quantum dots were embedded. Numerical simulation designed the emitter to realize efficient injection of the emitted photons into a single-mode optical fiber. Using a Hanbury-Brown and Twiss technique has proved that the photons through the fiber were single photons

  5. External-cavity high-power dual-wavelength tapered amplifier with tunable THz frequency difference

    DEFF Research Database (Denmark)

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2012-01-01

    A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W is achie......A tunable 800 nm high-power dual-wavelength diode laser system with double-Littrow external-cavity feedback is demonstrated. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. A maximum output power of 1.54 W...... is achieved with a frequency difference of 0.86 THz, the output power is higher than 1.3 W in the 5.0 THz range of frequency difference, and the amplified spontaneous emission intensity is more than 20 dB suppressed in the range of frequency difference. The beam quality factor M2 is 1.22±0.15 at an output...

  6. EFFECTS OF LIGHT WAVELENGTHS AND COHERENCE ON BASIDIOSPORES GERMINATION

    Directory of Open Access Journals (Sweden)

    Natalia Poyedinok

    2015-02-01

    Full Text Available The effects of light wavelengths and coherence on basidiospore germination of Agaricus bisporus, Flammulina velutipes, Ganoderma applanatum, Ganoderma lucidum, Hericium erinaceus, Lentinus edodes and Pleurotus ostreatus have been studied. Short-term low-intensity irradiation by coherent (laser light wavelength 488.0 nm and 632.8 nm at doses 45 and 230 mJ/cm2 has significantly increased the number of germinated basidiospores. It has established that there are differences in the photosensitivity not only between species but also between strains. Spores irradiation by 514.5 nm light has been either neutral or inhibitory. A comparative analysis of basidiospores sensitivity to laser and LED light has also been conducted. To stimulate germination of basidiospores and growth of monokaryons the most suitable solution was to use red coherent and incoherent light of 632.8 nm and 660,0 nm for A. bisporus, G. applanatum and P. ostreatus, red and blue coherent light of 632.8 nm and 488,0 nm for F. velutipes, and both red and blue laser and LED light G. lucidum and H. erinaceus and for L. edodes. No essential difference of a continuous wave mode and intermittent mode light effect at the same doses and wavelength on spore germination were revealed. Light influence has reduced germination time and formation of aerial mycelium on agar medium as compared to the original value and increased the growth rate of monosporous isolates. Characterization of basidiospores photosensitivity and development of environmentally friendly stimulating methods of their germination is important for creating highly effective technologies of mushrooms selection and cultivation.

  7. Topology Optimization of Sub-Wavelength Antennas

    DEFF Research Database (Denmark)

    Erentok, Aycan; Sigmund, Ole

    2011-01-01

    We propose a topology optimization strategy for the systematic design of a three-dimensional (3D), conductor-based sub-wavelength antenna. The post-processed finite-element (FE) models of the optimized structure are shown to be self-resonant, efficient and exhibit distorted omnidirectional...

  8. Characterization of ethanol concentrations at ultraviolet wavelength ...

    African Journals Online (AJOL)

    This paper presents the measurement of optical absorption spectrum for different concentrations of ethanol at ultraviolet wavelength. Ethanol absorption spectrum was measured using portable spectroscopy setup from Avantes. It consists of Balanced Deuterium Halogen light source and spectrometer. The light source can ...

  9. Smart wavelength meter for integrated photonics

    NARCIS (Netherlands)

    Benelajla, Meryem; Taballione, Caterina; Boller, Klaus J.

    2017-01-01

    Thermally tunable SiN waveguide microring resonators in connection with neural network readout algorithms appear promising for use as integrated optical wavelength meters. So far, we have observed long-term reliability and a temperature immunity of the readout across several degrees of ambient

  10. An automated wavelength selection for flame spectroscopy

    International Nuclear Information System (INIS)

    Hurteau, M.; Mislan, J.P.; Ashley, R.W.

    1976-01-01

    A simple electro-mechanical programming system is described for use with a flame spectrophotometer. Its application for automated sequential multi-element analysis is illustrated. Reproducibility of wavelength settings are within +-0.5 A. Precision and sensitivities are at least as good as those obtained for single element determinations. (author)

  11. Alien wavelength modeling tool and field trial

    DEFF Research Database (Denmark)

    Sambo, N.; Sgambelluri, A.; Secondini, M.

    2015-01-01

    A modeling tool is presented for pre-FEC BER estimation of PM-QPSK alien wavelength signals. A field trial is demonstrated and used as validation of the tool's correctness. A very close correspondence between the performance of the field trial and the one predicted by the modeling tool has been...

  12. Two-wavelength spatial-heterodyne holography

    Science.gov (United States)

    Hanson, Gregory R.; Bingham, Philip R.; Simpson, John T.; Karnowski, Thomas P.; Voelkl, Edgar

    2007-12-25

    Systems and methods are described for obtaining two-wavelength differential-phase holograms. A method includes determining a difference between a filtered analyzed recorded first spatially heterodyne hologram phase and a filtered analyzed recorded second spatially-heterodyned hologram phase.

  13. Short Review

    DEFF Research Database (Denmark)

    Lynnerup, Niels; Rühli, Frank

    2015-01-01

    modality in ancient mummy research. The aim of this short review is to address the advantages and pitfalls of this particular technique for such unique samples. We recommend that when results of X-ray examination of mummies are presented, the specific recording data should be listed, and any given finds...

  14. Short fusion

    CERN Multimedia

    2002-01-01

    French and UK researchers are perfecting a particle accelerator technique that could aid the quest for fusion energy or make X-rays that are safer and produce higher-resolution images. Led by Dr Victor Malka from the Ecole Nationale Superieure des Techniques Avancees in Paris, the team has developed a better way of accelerating electrons over short distances (1 page).

  15. Short communication

    African Journals Online (AJOL)

    UPuser

    Short communication. Polymorphisms of the CAST gene in the Meishan and five other pig populations in China. Q.S. Wang. 1. , Y.C. Pan. 1#. , L.B. Sun. 2 and H. Meng. 1. 1 Department of Animal Science, School of Agriculture and Biology, Shanghai Jiaotong University, Shanghai. 201101, P.R. China. 2 Shanghai Institute of ...

  16. SHORT COMMUNICATION

    African Journals Online (AJOL)

    a

    ______. *Corresponding author. E-mail: vani_chem@yahoo.com. SHORT COMMUNICATION. OXIDATION OF L-CYSTINE BY CHROMIUM(VI) - A KINETIC STUDY. Kalyan Kumar Adari, Annapurna Nowduri and Vani Parvataneni*. Department of Inorganic and Analytical Chemistry, School of Chemistry, Andhra University,.

  17. Short communication

    NARCIS (Netherlands)

    Pantophlet, Andre J.; Gilbert, M.S.; Gerrits, W.J.J.; Vonk, R.J.

    2017-01-01

    Heavy veal calves (4-6 mo old) often develop problems with insulin sensitivity. This could lead to metabolic disorders and impaired animal growth performance. Studies in various animal species have shown that the supplementation of short-chain fructo-oligosaccharides (scFOS) can improve insulin

  18. Continuum emission of excited sodium dimer

    International Nuclear Information System (INIS)

    Pardo, A.; Poyato, J.M.L.; Alonso, J.I.; Rico, F.R.

    1980-01-01

    A study has been made of the behaviour of excited molecular sodium using high-power Ar + laser radiation. A continuum emission was observed in the red wavelength region. This emission was thought to be caused by the formation of excited triatomic molecules. Energy transfer was observed from excited molecules to atoms. (orig.)

  19. Fluorescence of Bacteria, Pollens, and Naturally Occurring Airborne Particles: Excitation/Emission Spectra

    National Research Council Canada - National Science Library

    Hill, Steven C; Mayo, Michael W; Chang, Richard K

    2009-01-01

    The fluorescence intensity as a function of excitation and emission wavelengths (EEM spectra) was measured for different species of bacteria, biochemical constituents of cells, pollens, and vegetation...

  20. Using a fast dual-wavelength imaging ellipsometric system to measure the flow thickness profile of an oil thin film

    Science.gov (United States)

    Kuo, Chih-Wei; Han, Chien-Yuan; Jhou, Jhe-Yi; Peng, Zeng-Yi

    2017-11-01

    Dual-wavelength light sources with stroboscopic illumination technique were applied in a process of photoelastic modulated ellipsometry to retrieve two-dimensional ellipsometric parameters of thin films on a silicon substrate. Two laser diodes were alternately switched on and modulated by a programmable pulse generator to generate four short pulses at specific temporal phase angles in a modulation cycle, and short pulses were used to freeze the intensity variation of the PEM modulated signal that allows ellipsometric images to be captured by a charge-coupled device. Although the phase retardation of a photoelastic modulator is related to the light wavelength, we employed an equivalent phase retardation technique to avoid any setting from the photoelastic modulator. As a result, the ellipsometric parameters of different wavelengths may be rapidly obtained using this dual-wavelength ellipsometric system every 4 s. Both static and dynamic experiments are demonstrated in this work.

  1. The At-Wavelength Metrology Facility at BESSY-II

    Directory of Open Access Journals (Sweden)

    Franz Schäfers

    2016-02-01

    Full Text Available The At-Wavelength Metrology Facility at BESSY-II is dedicated to short-term characterization of novel UV, EUV and XUV optical elements, such as diffraction gratings, mirrors, multilayers and nano-optical devices like reflection zone plates. It consists of an Optics Beamline PM-1 and a Reflectometer in a clean-room hutch as a fixed end station. The bending magnet Beamline is a Plane Grating Monochromator beamline (c-PGM equipped with an SX700 monochromator. The beamline is specially tailored for efficient high-order suppression and stray light reduction. The versatile 11-axes UHV-Reflectometer can house life-sized optical elements, which are fully adjustable and of which the reflection properties can be measured in the full incidence angular range as well as in the full azimuthal angular range to determine polarization properties.

  2. Short-timescale variability in cataclysmic binaries

    International Nuclear Information System (INIS)

    Cordova, F.A.; Mason, K.O.

    1982-01-01

    Rapid variability, including flickering and pulsations, has been detected in cataclysmic binaries at optical and x-ray frequencies. In the case of the novalike variable TT Arietis, simultaneous observations reveal that the x-ray and optical flickering activity is strongly correlated, while short period pulsations are observed that occur at the same frequencies in both wavelength bands

  3. On the influence of crystal size and wavelength on native SAD phasing.

    Science.gov (United States)

    Liebschner, Dorothee; Yamada, Yusuke; Matsugaki, Naohiro; Senda, Miki; Senda, Toshiya

    2016-06-01

    Native SAD is an emerging phasing technique that uses the anomalous signal of native heavy atoms to obtain crystallographic phases. The method does not require specific sample preparation to add anomalous scatterers, as the light atoms contained in the native sample are used as marker atoms. The most abundant anomalous scatterer used for native SAD, which is present in almost all proteins, is sulfur. However, the absorption edge of sulfur is at low energy (2.472 keV = 5.016 Å), which makes it challenging to carry out native SAD phasing experiments as most synchrotron beamlines are optimized for shorter wavelength ranges where the anomalous signal of sulfur is weak; for longer wavelengths, which produce larger anomalous differences, the absorption of X-rays by the sample, solvent, loop and surrounding medium (e.g. air) increases tremendously. Therefore, a compromise has to be found between measuring strong anomalous signal and minimizing absorption. It was thus hypothesized that shorter wavelengths should be used for large crystals and longer wavelengths for small crystals, but no thorough experimental analyses have been reported to date. To study the influence of crystal size and wavelength, native SAD experiments were carried out at different wavelengths (1.9 and 2.7 Å with a helium cone; 3.0 and 3.3 Å with a helium chamber) using lysozyme and ferredoxin reductase crystals of various sizes. For the tested crystals, the results suggest that larger sample sizes do not have a detrimental effect on native SAD data and that long wavelengths give a clear advantage with small samples compared with short wavelengths. The resolution dependency of substructure determination was analyzed and showed that high-symmetry crystals with small unit cells require higher resolution for the successful placement of heavy atoms.

  4. Short Communication

    African Journals Online (AJOL)

    huis

    Short Communication. QTL analysis of production traits on SSC3 in a Large White×Meishan pig resource family. B. Zuo. 1. , Y.Z. Xiong. 1#. , Y.H. Su. 2. , C.Y. Deng. 1. , M.G. Lei. 1. , F.E. Li. 1. , R. Zheng. 1 and S.W. Jiang. 1. 1 Key Laboratory of Swine Genetics and Breeding, Ministry of Agriculture & Key Lab of Agricultural ...

  5. Long wavelength irregularities in the equatorial electrojet

    International Nuclear Information System (INIS)

    Kudeki, E.; Farley, D.T.; Fejer, B.G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach or exceed the ion-acoustic velocity even though the horizontal phase velocity of the wave is considerably smaller. A straightforward extension to the long wavelength regime of the usual linear theory of the electrojet instability explains this and several other observed features of these dominant primary waves

  6. Design alternatives for wavelength routing networks

    Science.gov (United States)

    Miliotis, K.; Papadimitriou, G. I.; Pomportsis, A. S.

    2003-03-01

    This paper attempts to provide a high level overview of many of the technologies employed in optical networks with a focus on wavelength-routing networks. Optical networks involve a number of technologies from the physics of light through protocols and networks architectures. In fact there is so much technology and know-how that most people involved with optical networks only have a full understanding of the narrow area they deal with. We start first examining the principles that govern light and its use as a wave guide, and then turn our focus to the various components that constitute an optical network and conclude with the description of all optical networks and wavelength-routed networks in greater detail.

  7. Long wavelength irregularities in the equatorial electrojet

    OpenAIRE

    Kudeki, E.; Farley, D. T.; Fejer, Bela G.

    1982-01-01

    We have used the radar interferometer technique at Jicamarca to study in detail irregularities with wavelengths of a few kilometers generated in the unstable equatorial electrojet plasma during strong type 1 conditions. In-situ rocket observations of the same instability process are discussed in a companion paper. These large scale primary waves travel essentially horizontally and have large amplitudes. The vertical electron drift velocities driven by the horizontal wave electric fields reach...

  8. GINGER simulations of short-pulse effects in the LEUTL FEL

    International Nuclear Information System (INIS)

    Huang, Z.; Fawley, W.M.

    2001-01-01

    While the long-pulse, coasting beam model is often used in analysis and simulation of self-amplified spontaneous emission (SASE) free-electron lasers (FELs), many current SASE demonstration experiments employ relatively short electron bunches whose pulse length is on the order of the radiation slippage length. In particular, the low-energy undulator test line (LEUTL) FEL at the Advanced Photon Source has recently lased and nominally saturated in both visible and near-ultraviolet wavelength regions with a sub-ps pulse length that is somewhat shorter than the total slippage length in the 22-m undulator system. In this paper we explore several characteristics of the short pulse regime for SASE FELs with the multidimensional, time-dependent simulation code GINGER, concentrating on making a direct comparison with the experimental results from LEUTL. Items of interest include the radiation gain length, pulse energy, saturation position, and spectral bandwidth. We address the importance of short-pulse effects when scaling the LEUTL results to proposed x-ray FELs and also briefly discuss the possible importance of coherent spontaneous emission at startup

  9. Acoustic emission

    International Nuclear Information System (INIS)

    Nichols, R.W.

    1976-01-01

    The volume contains six papers which together provide an overall review of the inspection technique known as acoustic emission or stress wave emission. The titles are: a welder's introduction to acoustic emission technology; use of acoustic emission for detection of defects as they arise during fabrication; examples of laboratory application and assessment of acoustic emission in the United Kingdom; (Part I: acoustic emission behaviour of low alloy steels; Part II: fatigue crack assessment from proof testing and continuous monitoring); inspection of selected areas of engineering structures by acoustic emission; Japanese experience in laboratory and practical applications of acoustic emission to welded structures; and ASME acoustic emission code status. (U.K.)

  10. Optically coupled cavities for wavelength switching

    Energy Technology Data Exchange (ETDEWEB)

    Costazo-Caso, Pablo A; Granieri, Sergio; Siahmakoun, Azad, E-mail: pcostanzo@ing.unlp.edu.ar, E-mail: granieri@rose-hulman.edu, E-mail: siahmako@rose-hulman.edu [Department of Physics and Optical Engineering, Rose-Hulman Institute of Technology, 5500 Wabash Avenue, Terre Haute, IN 47803 (United States)

    2011-01-01

    An optical bistable device which presents hysteresis behavior is proposed and experimentally demonstrated. The system finds applications in wavelength switching, pulse reshaping and optical bistability. It is based on two optically coupled cavities named master and slave. Each cavity includes a semiconductor optical amplifier (SOA), acting as the gain medium of the laser, and two pair of fiber Bragg gratings (FBG) which define the lasing wavelength (being different in each cavity). Finally, a variable optical coupler (VOC) is employed to couple both cavities. Experimental characterization of the system performance is made analyzing the effects of the coupling coefficient between the two cavities and the driving current in each SOA. The properties of the hysteretic bistable curve and switching can be controlled by adjusting these parameters and the loss in the cavities. By selecting the output wavelength ({lambda}{sub 1} or {lambda}{sub 2}) with an external filter it is possible to choose either the invert or non-invert switched signal. Experiments were developed employing both optical discrete components and a photonic integrated circuit. They show that for 8 m-long cavities the maximum switching frequency is about 500 KHz, and for 4 m-long cavities a minimum rise-time about 21 ns was measured. The switching time can be reduced by shortening the cavity lengths and using photonic integrated circuits.

  11. Wavelength switching in an optical klystron

    International Nuclear Information System (INIS)

    Berryman, K.W.; Smith, T.I.

    1995-01-01

    A symmetric optical klystron consists of two identical undulator sections separated a dispersive section. For a device of a given length, an optical klystron is capable of producing much more bunching, and therefore more gain, than a traditional undulator. Another consequence of introducing dispersion between two undulator sections is that the overall spontaneous radiation pattern results from the interference between the two undulator sections, and as such resembles a standard undulator radiation pattern modulated by a sinusoidal interference term. The presence of several wavelength peaks in the spontaneous lineshape implies an equal number of peaks in the gain spectrum. If the strength of the dispersion section is adjusted to provide nearly equal gain on the two largest of these peaks, then they will compete, and the FEL may switch wavelengths based on noise, cavity length, or other perturbations. We provide the first observations of this behavior, using the FIREFLY system at the Stanford Picosecond FEL Center. In FIREFLY, relative wavelength switching by more than 3%--more than twice the laser linewidth-has been observed by varying dispersion section strength, while at intermediate points stable switching has also been observed as a function of cavity length

  12. Multiple wavelength X-ray monochromators

    International Nuclear Information System (INIS)

    Steinmeyer, P.A.

    1992-01-01

    An improved apparatus and method is provided for separating input x-ray radiation containing first and second x-ray wavelengths into spatially separate first and second output radiation which contain the first and second x-ray wavelengths, respectively. The apparatus includes a crystalline diffractor which includes a first set of parallel crystal planes, where each of the planes is spaced a predetermined first distance from one another. The crystalline diffractor also includes a second set of parallel crystal planes inclined at an angle with respect to the first set of crystal planes where each of the planes of the second set of parallel crystal planes is spaced a predetermined second distance from one another. In one embodiment, the crystalline diffractor is comprised of a single crystal. In a second embodiment, the crystalline diffractor is comprised of a stack of two crystals. In a third embodiment, the crystalline diffractor includes a single crystal that is bent for focusing the separate first and second output x-ray radiation wavelengths into separate focal points. 3 figs

  13. Dual-wavelength electroluminescence from an n-ZnO/p-GaN heterojunction light emitting diode

    International Nuclear Information System (INIS)

    Tsai, Bor-Sheng; Chiu, Hung-Jen; Chen, Tai-Hong; Lai, Li-Wen; Ho, Chai-Cheng; Liu, Day-Shan

    2015-01-01

    Highlights: • The LEDs fabricated by 450 °C- and 700 °C-annealed n-ZnO/p-GaN heterojunction structures were investigated. • The structure annealed at 700 °C emitted yellowish light composed of the dual-wavelength radiations centered at 420 and 610 nm. • The long-wavelength radiation was attributed to emerge from the deep-level emission and the Ga–O interlayer emission. - Abstract: We investigated the electro-optical properties of light emitting diodes (LEDs) fabricated by using the n-ZnO/p-GaN heterojunction structures annealed at 450 °C and 700 °C, in vacuum ambient. A dominant near-UV emission at approximately 420 nm was observed from the LED fabricated by the 450 °C-annealed n-ZnO/p-GaN heterojunction structure, whereas that of the structure annealed at 700 °C emitted a yellowish light composed of the dual-wavelength emissions centered at 420 and 610 nm. The mechanism responsible for the broad long-wavelength radiation was ascribed to the transitions associated with both the deep-level emissions due to the activation of the native defects on the n-ZnO side surface and the formation of the Ga–O interlayer resulting from the in-diffusion of oxygen atoms to the p-GaN side surface of the n-ZnO/p-GaN interface.

  14. Predamage threshold electron emission from insulator and semiconductor surfaces

    International Nuclear Information System (INIS)

    Siekhaus, W.J.; Kinney, J.H.; Milam, D.

    1985-01-01

    Predamage electron emission shows a dependence on fluence, bandgap and wavelength consistent with multiphoton excitation across the bandgap and inconsistent with avalanche ionization and thermionic emission models. The electron emission scales with pulselength as 1/√T. 6 references, 8 figures, 1 table

  15. Wavelength switching dynamics of two-colour semiconductor lasers with optical injection and feedback

    International Nuclear Information System (INIS)

    Osborne, S; Heinricht, P; Brandonisio, N; Amann, A; O’Brien, S

    2012-01-01

    The wavelength switching dynamics of two-colour semiconductor lasers with optical injection and feedback are presented. These devices incorporate slotted regions etched into the laser ridge waveguide for tailoring the output spectrum. Experimental measurements are presented demonstrating that optical injection in one or both modes of these devices can induce wavelength bistability. Measured switching dynamics with modulated optical injection are shown to be in excellent agreement with numerical simulations based on a simple rate equation model. We also demonstrate experimentally that time-delayed optical feedback can induce wavelength bistability for short external cavity lengths. Numerical simulations indicate that this two-colour optical feedback system can provide fast optical memory functionality based on injected optical pulses without the need for an external holding beam. (paper)

  16. A Broad 22 Micron Emission Feature in the Carina Nebula H ii Region.

    Science.gov (United States)

    Chan; Onaka

    2000-04-10

    We report the detection of a broad 22 µm emission feature in the Carina Nebula H ii region by the Infrared Space Observatory (ISO) short-wavelength spectrometer. The feature shape is similar to that of the 22 µm emission feature of newly synthesized dust observed in the Cassiopeia A supernova remnant. This finding suggests that both of the features are arising from the same carrier and that supernovae are probably the dominant production sources of this new interstellar grain. A similar broad emission dust feature is also found in the spectra of two starburst galaxies from the ISO archival data. This new dust grain could be an abundant component of interstellar grains and can be used to trace the supernova rate or star formation rate in external galaxies. The existence of the broad 22 µm emission feature complicates the dust model for starburst galaxies and must be taken into account correctly in the derivation of dust color temperature. Mg protosilicate has been suggested as the carrier of the 22 µm emission dust feature observed in Cassiopeia A. The present results provide useful information in studies on the chemical composition and emission mechanism of the carrier.

  17. The wavelength dependence of gold nanorod-mediated optical breakdown during infrared ultrashort pulses

    Energy Technology Data Exchange (ETDEWEB)

    Davletshin, Yevgeniy R.; Kumaradas, J. Carl [Department of Physics, Ryerson University, Toronto, ON (Canada)

    2017-04-15

    This paper investigates the wavelength dependence of the threshold of gold nanorod-mediated optical breakdown during picosecond and femtosecond near infrared optical pulses. It was found that the wavelength dependence in the picosecond regime is governed solely by the changes of a nanorod's optical properties. On the other hand, the optical breakdown threshold during femtosecond pulse exposure falls within one of two regimes. When the ratio of the maximum electric field from the outside to the inside of the nanorod is less then 7 (the absorption regime) the seed electrons are initiated by photo-thermal emission, and the wavelength dependence in the threshold of optical breakdown is the result of optical properties of the nanoparticle. When the ratio is greater than 7 (the near-field regime) more seed electrons are initiated by multiphoton ionization, and the wavelength dependence of the threshold of optical breakdown results from a combination of nanorod's optical properties and transitions in the order of multiphoton ionization. The findings of this study can guide the design of nanoparticle based optical breakdown applications. This analysis also deepens the understanding of nanoparticle-mediated laser induced breakdown for picosecond and femtosecond pulses at near infrared wavelengths. (copyright 2017 by WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  18. High power multiple wavelength diode laser stack for DPSSL application without temperature control

    Science.gov (United States)

    Hou, Dong; Yin, Xia; Wang, Jingwei; Chen, Shi; Zhan, Yun; Li, Xiaoning; Fan, Yingmin; Liu, Xingsheng

    2018-02-01

    High power diode laser stack is widely used in pumping solid-state laser for years. Normally an integrated temperature control module is required for stabilizing the output power of solid-state laser, as the output power of the solid-state laser highly depends on the emission wavelength and the wavelength shift of diode lasers according to the temperature changes. However the temperature control module is inconvenient for this application, due to its large dimension, high electric power consumption and extra adding a complicated controlling system. Furthermore, it takes dozens of seconds to stabilize the output power when the laser system is turned on. In this work, a compact hard soldered high power conduction cooled diode laser stack with multiple wavelengths is developed for stabilizing the output power of solid-state laser in a certain temperature range. The stack consists of 5 laser bars with the pitch of 0.43mm. The peak output power of each bar in the diode laser stack reaches as much as 557W and the combined lasing wavelength spectrum profile spans 15nm. The solidstate laser, structured with multiple wavelength diode laser stacks, allows the ambient temperature change of 65°C without suddenly degrading the optical performance.

  19. Short recovery time NMR probe

    International Nuclear Information System (INIS)

    Ramia, M.E.; Martin, C.A.; Jeandrevin, S.

    2011-01-01

    A NMR probe for low frequency and short recovery time is presented in this work. The probe contains the tuning circuit, diode expanders and quarter wavelength networks to protect the receiver from both the amplifier noise and the coil ringing following the transmitter power pulse. It also possesses a coil damper which is activated by of non active components. The probe performance shows a recovery time of about of 15μs a sensitive Q factor reduction and an increase of the signal to noise ratio of about 68% during the reception at a work frequency of 2 MHz. (author)

  20. The Wavelength Dependence of the Lunar Phase Curve as Seen by the LRO LAMP

    Science.gov (United States)

    Liu, Y.; Retherford, K. D.; Greathouse, T. K.; Hendrix, A. R.; Mandt, K.; Gladstone, R.; Cahill, J. T.; Egan, A.; Kaufmann, D. E.; Grava, C.; Pryor, W. R.

    2016-12-01

    The Lunar Reconnaissance Orbiter (LRO) Lyman Alpha Mapping Project (LAMP) provides global coverage of both nightside and dayside of the Moon in the far ultraviolet (FUV) wavelengths. The nightside observations use roughly uniform diffuse illumination sources from interplanetary medium Lyman-α sky glow and UV-bright stars so that traditional photometric corrections do not apply. In contrast, the dayside observations use sunlight as its illumination source where bidirectional reflectance is measured. The bidirectional reflectance is dependent on the incident, emission, and phase angles as well as the soil properties. Thus the comparisons of dayside mapping and nightside mapping techniques offer a method for cross-comparing the photometric correction factors because the observations are made under different lighting and viewing conditions. Specifically, the nightside data well constrain the single-scattering coefficient. We'll discuss the wavelength dependence of the lunar phase curve as seen by the LAMP instrument in dayside data. Our preliminary results indicate that the reflectance in the FUV wavelengths decreases with the increasing phase angles from 0° to 90°, similar to the phase curve in the UV-visible wavelengths as studied by Hapke et al. (2012) using LRO wide angle camera (WAC) data, among other visible-wavelength lunar studies. Particularly, we'll report how coherent backscattering and shadow hiding contribute to the opposition surge, given the fact that the albedo at FUV wavelengths is extremely low and thus multiple scattering is significantly less important. Finally, we'll report the derived Hapke parameters at FUV wavelengths for our study areas.

  1. Biophotonic markers of malignancy: Discriminating cancers using wavelength-specific biophotons

    Directory of Open Access Journals (Sweden)

    Nirosha J. Murugan

    2018-03-01

    Full Text Available Early detection is a critically important factor when successfully diagnosing and treating cancer. Whereas contemporary molecular techniques are capable of identifying biomarkers associated with cancer, surgical interventions are required to biopsy tissue. The common imaging alternative, positron-emission tomography (PET, involves the use of nuclear material which poses some risks. Novel, non-invasive techniques to assess the degree to which tissues express malignant properties are now needed. Recent developments in biophoton research have made it possible to discriminate cancerous cells from normal cells both in vitro and in vivo. The current study expands upon a growing body of literature where we classified and characterized malignant and non-malignant cell types according to their biophotonic activity. Using wavelength-exclusion filters, we demonstrate that ratios between infrared and ultraviolet photon emissions differentiate cancer and non-cancer cell types. Further, we identified photon sources associated with three filters (420-nm, 620-nm., and 950-nm which classified cancer and non-cancer cell types. The temporal increases in biophoton emission within these wavelength bandwidths is shown to be coupled with intrisitic biomolecular events using Cosic's resonant recognition model. Together, the findings suggest that the use of wavelength-exclusion filters in biophotonic measurement can be employed to detect cancer in vitro.

  2. Wavelength dependence of the linear growth rate of the Es layer instability

    Directory of Open Access Journals (Sweden)

    R. B. Cosgrove

    2007-06-01

    Full Text Available It has recently been shown, by computation of the linear growth rate, that midlatitude sporadic-E (Es layers are subject to a large scale electrodynamic instability. This instability is a logical candidate to explain certain frontal structuring events, and polarization electric fields, which have been observed in Es layers by ionosondes, by coherent scatter radars, and by rockets. However, the original growth rate derivation assumed an infinitely thin Es layer, and therefore did not address the short wavelength cutoff. Also, the same derivation ignored the effects of F region loading, which is a significant wavelength dependent effect. Herein is given a generalized derivation that remedies both these short comings, and thereby allows a computation of the wavelength dependence of the linear growth rate, as well as computations of various threshold conditions. The wavelength dependence of the linear growth rate is compared with observed periodicities, and the role of the zeroth order meridional wind is explored. A three-dimensional paper model is used to explain the instability geometry, which has been defined formally in previous works.

  3. Influence of ns-laser wavelength in laser-induced breakdown spectroscopy for discrimination of painting techniques

    Science.gov (United States)

    Bai, Xueshi; Syvilay, Delphine; Wilkie-Chancellier, Nicolas; Texier, Annick; Martinez, Loic; Serfaty, Stéphane; Martos-Levif, Dominique; Detalle, Vincent

    2017-08-01

    The influence of ns-laser wavelength to discriminate ancient painting techniques such as are fresco, casein, animal glue, egg yolk and oil was investigated in this work. This study was carried out with a single shot laser on samples covered by a layer made of a mixture of the cinnabar pigment and different binders. Three wavelengths based on Nd: YAG laser were investigated (1064, 532 and 266 nm). The plasma is controlled at the same electron temperature after an adjustment of pulse energy for these three wavelengths on a fresco sample without organic binder. This approach allows to eliminate the effects of laser pulse energy and the material laser absorption. Afterwards, the emission spectra were compared to separate different techniques. The organic binding media has been separated based on the relative emission intensity of the present CN or C2 rovibrational emissions. In order to test the capability of separating or identifying, the chemometric approach (PCA) was applied to the different matrix. The different solutions in term of wavelength range to optimise the identification was investigated. We focused on the evaluation for the laser wavelength to insure a better separation. The different capacity was interpreted by differentiating the binders by the altered interaction mechanisms between the laser photon and the binders. Also, the electron temperature in the plasma was estimated, which provided the evidences to our findings.

  4. NORTRIP emission model user guide

    Energy Technology Data Exchange (ETDEWEB)

    Denby, Rolstad Bruce

    2012-07-01

    The NORTRIP emission model has been developed at NILU, in conjunction with other Nordic institutes, to model non-exhaust traffic induced emissions. This short summary document explains how to run the NORTRIP model from the MATLAB environment or by using the executable user interface version. It also provides brief information on input files and the model architecture.(Author)

  5. Optical frequency-domain reflectometry using multiple wavelength-swept elements of a DFB laser array

    Science.gov (United States)

    DiLazaro, Tom; Nehmetallah, Georges

    2017-02-01

    Coherent optical frequency-domain reflectometry (C-OFDR) is a distance measurement technique with significant sensitivity and detector bandwidth advantages over normal time-of-flight methods. Although several swept-wavelength laser sources exist, many exhibit short coherence lengths, or require precision mechanical tuning components. Semiconductor distributed feedback lasers (DFBs) are advantageous as a mid-to-long range OFDR source because they exhibit a narrow linewidth and can be rapidly tuned simply via injection current. However, the sweep range of an individual DFB is thermally limited. Here, we present a novel high-resolution OFDR system that uses a compact, monolithic 12-element DFB array to create a continuous, gap-free sweep over a wide wavelength range. Wavelength registration is provided by the incorporation of a HCN gas cell and reference interferometer. The wavelength-swept spectra of the 12 DFBs are combined in post-processing to achieve a continuous total wavelength sweep of more than 40 nm (5.4 THz) in the telecommunications C-Band range.

  6. Space- and time-resolved diagnostics of soft x-ray emission from laser plasmas

    International Nuclear Information System (INIS)

    Richardson, M.C.; Jaanimagi, P.A.; Chen, H.

    1988-01-01

    The analysis of soft x-ray emission from plasmas created by intense short-wavelength laser radiation can provide much useful information on the density, temperature and ionization distribution of the plasma. Until recently, limitations of sensitivity and the availability of suitable x-ray optical elements have restricted studies of soft x-ray emission from laser plasmas. In this paper, the authors describe novel instrumentation which provides high sensitivity in the soft x-ray spectrum with spatial and temporal resolution in the micron and picosecond ranges respectively. These systems exploit advances made in soft x-ray optic and electro-optic technology. Their application in current studies of laser fusion, x-ray lasers, and high density atomic physics are discussed

  7. A radiation research apparatus sensitive to wavelength

    International Nuclear Information System (INIS)

    1980-01-01

    The apparatus described is equipped with a radiation source with a tuning device for the generation of X radiation of at least two different wavelength spectra. The detector with ionisation chamber is able to discriminate between these spectra. This is done with the aid of an auxillary electrode between the entrance window and a high voltage electrode. With a lower source of voltage this electrode has a potential equal to the high voltage electrode potential and with a higher voltage source it has a potential equal to the signal electrode potential. (Th.P.)

  8. Wavelength-agnostic WDM-PON System

    DEFF Research Database (Denmark)

    Wagner, Christoph; Eiselt, Michael; Zou, S.

    2016-01-01

    on the standardization status of this lowcost system in the new ITU-T G.metro draft recommendation, in the context of autonomous tuning. We also discuss some low-effort implementations of the pilot-tone labels and investigate the impact of these labels on the transmission channels.......Next-generation WDM-PON solutions for metro and access systems will take advantage of remotely controlled wavelength-tunable ONUs to keep system costs as low as possible. For such a purpose, each ONU signal can be labeled by a pilot tone modulated onto the optical data stream. We report...

  9. Sub-wavelength imaging at radio frequency

    International Nuclear Information System (INIS)

    Wiltshire, M C K; Pendry, J B; Hajnal, J V

    2006-01-01

    A slab of material with a negative permeability can act as a super-lens for magnetic fields and generate images with a sub-wavelength resolution. We have constructed an effective medium using a metamaterial with negative permeability in the region of 24 MHz, and used this to form images in free space of radio frequency magnetic sources. Measurements of these images show that a resolution of approximately λ/64 has been achieved, consistent with both analytical and numerical predictions. (letter to the editor)

  10. Gold Photoluminescence: Wavelength and Polarization Engineering

    DEFF Research Database (Denmark)

    Andersen, Sebastian Kim Hjælm; Pors, Anders Lambertus; Bozhevolnyi, Sergey I.

    2015-01-01

    We demonstrate engineering of the spectral content and polarization of photoluminescence (PL) from arrayed gold nanoparticles atop a subwavelength-thin dielectric spacer and optically-thick gold film, a configuration that supports gap-surface plasmon resonances (GSPRs). Choice of shapes...... and dimensions of gold nanoparticles influences the GSPR wavelength and polarization characteristics, thereby allowing us to enhance and spectrally mold the plasmon-assisted PL while simultaneously controlling its polarization. In order to understand the underlying physics behind the plasmon-enhanced PL, we...

  11. Tailoring Chirped Moiré Fiber Bragg Gratings for Wavelength-Division-Multiplexing and Optical Code-Division Multiple-Access Applications

    Science.gov (United States)

    Chen, Lawrence R.; Smith, Peter W. E.

    The design and fabrication of chirped Moiré fiber Bragg gratings (CMGs) are presented, which can be used in either (1) transmission as passband filters for providing wavelength selectivity in wavelength-division-multiplexed (WDM) systems or (2) reflection as encoding/decoding elements to decompose short broadband pulses in both wavelength and time in order to implement an optical code-division multiple-access (OCDMA) system. In transmission, the fabricated CMGs have single or multiple flattened passbands ( 12 dB isolation and near constant in-band group delay. It is shown that these filters do not produce any measurable dispersion-induced power penalties when used to provide wavelength selectivity in 2.5 Gbit/s systems. It is also demonstrated how CMGs can be used in reflection to encode/decode short pulses from a wavelength-tunable mode-locked Er-doped fiber laser.

  12. Wavelength converter placement in optical networks with dynamic traffic

    DEFF Research Database (Denmark)

    Buron, Jakob Due; Ruepp, Sarah Renée; Wessing, Henrik

    2008-01-01

    We evaluate the connection provisioning performance of GMPLS-controlled wavelength routed networks under dynamic traffic load and using three different wavelength converter placement heuristics. Results show that a simple uniform placement heuristic matches the performance of complex heuristics...

  13. Passively synchronized dual-wavelength Q-switched lasers

    DEFF Research Database (Denmark)

    Janousek, Jiri; Tidemand-Lichtenberg, Peter; Mortensen, Jesper Liltorp

    We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG.......We present a simple and efficient way of generating synchronized Q-switched pulses at wavelengths hundreds of nanometers apart. This principle can result in new pulsed all-solid-state light sources at new wavelengths based on SFG....

  14. Meter-wavelength VLBI. III. Pulsars

    International Nuclear Information System (INIS)

    Vandenberg, N.R.; Clark, T.A.; Clark, W.C.; Erickson, W.C.; Resch, G.M.; Broderick, J.J.

    1976-01-01

    The results and analysis of observations of pulsars, especially the Crab Nebula pulsar, taken during a series of meter-wavelength very long baseline interferometry (VLBI) experiments are discussed. Based on a crude 144 MHz visibility curve which is consistent with a Gaussian brightness distribution, the measured visibilities at 196, 111, and 74 MHz were interpreted to yield apparent angular diameters (at half-power) of 0 .03 +- 0 .01, 0 .07 +- 0 .01, and 0 .18 +- 0 .01, respectively. These sizes scale approximately as wavelength-squared, and the 74 MHz size agrees with recent observations using interplanetary scintillation techniques.The VLBI-measured total flux densities lie on the extrapolation from higher frequencies of the pulsing flux densities. Variations in the total flux density up to 25 percent were observed. A lack of fine structure other than the pulsar in the nebula is indicated by our simple visibility curves. The pulse shapes observed with the interferometer are similar to single-dish measurements at 196 MHz but reveal a steady, nonpulsing component at 111 MHz. The ratio of pulsing to total power was approximately equal to one-half but varied with time. No pulsing power was detected at 74 MHz. It was found that four strong, low-dispersion pulsars were only slightly resolved

  15. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.W.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in TFTR L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  16. WDM cross-connect cascade based on all-optical wavelength converters for routing and wavelength slot interchanging using a reduced number of internal wavelengths

    DEFF Research Database (Denmark)

    Pedersen, Rune Johan Skullerud; Mikkelsen, Benny; Jørgensen, Bo Foged

    1998-01-01

    interchanging can be used to create a robust and nonblocking OXC. However, for an OXC with n fiber inlets each carrying m wavelengths the OXC requires n×m internal wavelengths, which constrains the size of the cross-connect. In this paper we therefore propose and demonstrate an architecture that uses a reduced......Optical transport layers need rearrangeable wavelength-division multiplexing optical cross-connects (OXCs) to increase the capacity and flexibility of the network. It has previously been shown that a cross-connect based on all-optical wavelength converters for routing as well as wavelength slot...... set of internal wavelengths without sacrificing cross-connecting capabilities. By inserting a partly equipped OXC with the new architecture in a 10-Gbit/s re-circulating loop setup we demonstrate the possibility of cascading up to ten OXCs. Furthermore, we investigate the regenerating effect...

  17. Heterodyne spatial interferometry of circumstellar dust shells at a wavelength of 11 microns

    International Nuclear Information System (INIS)

    Sutton, E.C.

    1979-01-01

    The spatial distribution of the 11 micron thermal emission from circumstellar dust envelopes has been studied using an infrared heterodyne interferometer. Circumstellar dust envelopes often exist around cool, late-type stars. These envelopes radiate strongly at 11 microns, particularly if they are composed of silicate grains, which have a strong emission feature near this wavelength. By measuring the spatial distribution of this dust emission it is possible to probe the temperatures and densities of the circumstellar material and thereby to gain an understanding of the structures of circumstellar envelopes. Among the sources which have been observed with this interferometer are α Orionis, o Ceti, VY Canis Majoris, and IRC + 10216. The 11 micron brightness distributions of these objects all have spatially extended dust-emission components which are resolved in these measurements. The dust envelopes of α Orionis and o Ceti are optically thin, having optical depths at 11 microns of 0.02 and 0.04, respectively. In addition, variations are seen in the 11 micron brightness distribution of o Ceti which correlate with the stellar variability. These variations primarily represent changes in the relative amount of spatially compact photospheric emission and spatially extended dust emission. The source VY Canis Majoris, on the other had, has a dust envelope which is optically thick at 11 microns. The dust envelope of IRC + 10216, although optically thick at visible wavelengths, does not seem to be optically thick at 11 microns since there is a spatially compact component of the 11 micron brightness distribution which presumably represents emission from the central star

  18. Dynamic Sensor Interrogation Using Wavelength-Swept Laser with a Polygon-Scanner-Based Wavelength Filter

    Science.gov (United States)

    Kwon, Yong Seok; Ko, Myeong Ock; Jung, Mi Sun; Park, Ik Gon; Kim, Namje; Han, Sang-Pil; Ryu, Han-Cheol; Park, Kyung Hyun; Jeon, Min Yong

    2013-01-01

    We report a high-speed (∼2 kHz) dynamic multiplexed fiber Bragg grating (FBG) sensor interrogation using a wavelength-swept laser (WSL) with a polygon-scanner-based wavelength filter. The scanning frequency of the WSL is 18 kHz, and the 10 dB scanning bandwidth is more than 90 nm around a center wavelength of 1,540 nm. The output from the WSL is coupled into the multiplexed FBG array, which consists of five FBGs. The reflected Bragg wavelengths of the FBGs are 1,532.02 nm, 1,537.84 nm, 1,543.48 nm, 1,547.98 nm, and 1,553.06 nm, respectively. A dynamic periodic strain ranging from 500 Hz to 2 kHz is applied to one of the multiplexed FBGs, which is fixed on the stage of the piezoelectric transducer stack. Good dynamic performance of the FBGs and recording of their fast Fourier transform spectra have been successfully achieved with a measuring speed of 18 kHz. The signal-to-noise ratio and the bandwidth over the whole frequency span are determined to be more than 30 dB and around 10 Hz, respectively. We successfully obtained a real-time measurement of the abrupt change of the periodic strain. The dynamic FBG sensor interrogation system can be read out with a WSL for high-speed and high-sensitivity real-time measurement. PMID:23899934

  19. MODELING MULTI-WAVELENGTH PULSE PROFILES OF THE MILLISECOND PULSAR PSR B1821–24

    Energy Technology Data Exchange (ETDEWEB)

    Du, Yuanjie; Shuai, Ping; Bei, Xiaomin; Chen, Shaolong; Fu, Linzhong; Huang, Liangwei; Lin, Qingqing; Meng, Jing; Wu, Yaojun; Zhang, Hengbin; Zhang, Qian; Zhang, Xinyuan [Qian Xuesen Laboratory of Space Technology, NO. 104, Youyi Road, Haidian District, Beijing 100094 (China); Qiao, Guojun, E-mail: dyj@nao.cas.cn [School of Physics, Peking University, Beijing 100871 (China)

    2015-03-10

    PSR B1821–24 is a solitary millisecond pulsar that radiates multi-wavelength pulsed photons. It has complex radio, X-ray, and γ-ray pulse profiles with distinct peak phase separations that challenge the traditional caustic emission models. Using the single-pole annular gap model with a suitable magnetic inclination angle (α = 40°) and viewing angle (ζ = 75°), we managed to reproduce its pulse profiles of three wavebands. It is found that the middle radio peak originated from the core gap region at high altitudes, and the other two radio peaks originated from the annular gap region at relatively low altitudes. Two peaks of both X-ray and γ-ray wavebands basically originated from the annular gap region, while the γ-ray emission generated from the core gap region contributes somewhat to the first γ-ray peak. Precisely reproducing the multi-wavelength pulse profiles of PSR B1821–24 enables us to understand emission regions of distinct wavebands and justify pulsar emission models.

  20. Temperature Characteristics of Monolithically Integrated Wavelength-Selectable Light Sources

    International Nuclear Information System (INIS)

    Han Liang-Shun; Zhu Hong-Liang; Zhang Can; Ma Li; Liang Song; Wang Wei

    2013-01-01

    The temperature characteristics of monolithically integrated wavelength-selectable light sources are experimentally investigated. The wavelength-selectable light sources consist of four distributed feedback (DFB) lasers, a multimode interferometer coupler, and a semiconductor optical amplifier. The oscillating wavelength of the DFB laser could be modulated by adjusting the device operating temperature. A wavelength range covering over 8.0nm is obtained with stable single-mode operation by selecting the appropriate laser and chip temperature. The thermal crosstalk caused by the lateral heat spreading between lasers operating simultaneously is evaluated by oscillating-wavelength shift. The thermal crosstalk approximately decreases exponentially as the increasing distance between lasers

  1. Analysis of subsystems in wavelength-division-multiplexing networks

    DEFF Research Database (Denmark)

    Liu, Fenghai

    2001-01-01

    Wavelength division multiplexing (WDM) technology together with optical amplification has created a new era for optical communication. Transmission capacity is greatly increased by adding more and more wavelength channels into a single fiber, as well as by increasing the line rate of each channel...... in semiconductor optical amplifiers (SOAs), and dispersion managed fiber sections. New subsystems are also proposed in the thesis: a modular 2×2 multiwavelength cross-connect using wavelength switching blocks, a wavelength converter based on cross phase modulation in a semiconductor modulator, a wavelength...

  2. Spin and wavelength multiplexed nonlinear metasurface holography

    Science.gov (United States)

    Ye, Weimin; Zeuner, Franziska; Li, Xin; Reineke, Bernhard; He, Shan; Qiu, Cheng-Wei; Liu, Juan; Wang, Yongtian; Zhang, Shuang; Zentgraf, Thomas

    2016-06-01

    Metasurfaces, as the ultrathin version of metamaterials, have caught growing attention due to their superior capability in controlling the phase, amplitude and polarization states of light. Among various types of metasurfaces, geometric metasurface that encodes a geometric or Pancharatnam-Berry phase into the orientation angle of the constituent meta-atoms has shown great potential in controlling light in both linear and nonlinear optical regimes. The robust and dispersionless nature of the geometric phase simplifies the wave manipulation tremendously. Benefitting from the continuous phase control, metasurface holography has exhibited advantages over conventional depth controlled holography with discretized phase levels. Here we report on spin and wavelength multiplexed nonlinear metasurface holography, which allows construction of multiple target holographic images carried independently by the fundamental and harmonic generation waves of different spins. The nonlinear holograms provide independent, nondispersive and crosstalk-free post-selective channels for holographic multiplexing and multidimensional optical data storages, anti-counterfeiting, and optical encryption.

  3. Aligning of single and multiple wavelength chromatographic

    DEFF Research Database (Denmark)

    Nielsen, Niels-Peter Vest; Carstensen, Jens Michael; Smedsgaard, Jørn

    1998-01-01

    optimised warping (COW) using two input parameters which can be estimated from the observed peak width. COW is demonstrated on constructed single trace chromatograms and on single and multiple wavelength chromatograms obtained from HPLC diode detection analyses of fungal extractsA copy of the C program......The use of chemometric data processing is becoming an important part of modern chromatography. Most chemometric analyses are performed on reduced data sets using areas of selected peaks detected in the chromatograms, which means a loss of data and introduces the problem of extracting peak data from...... to utilise the entire data matrix or rely on peak detection, thus having the same limitations as the commonly used chemometric procedures. The method presented uses the entire chromatographic data matrices and does not require any preprocessing e.g., peak detection. It relies on piecewise linear correlation...

  4. Single wavelength standard wiggler for PEP

    International Nuclear Information System (INIS)

    Brunk, W.; Fischer, G.; Spencer, J.

    1979-03-01

    A 1lambda planar wiggler has been designed that will be used for the initial operation of the 4 to 18 GeV storage ring PEP. Three of these wigglers will be installed symmetrically around the ring at 120 0 intervals in three of six available 5 m straight sections with the purpose of providing: (1) beam size control to obtain better luminosities below 15 GeV, and (2) decreased damping times to obtain better injection rates at lower energies. Design goals are discussed and a description of the final system including cost estimates is given. Expected results and usage in PEP are discussed. Some possibilities for production of synchrotron radiation and beam monitoring with shorter wavelength, multiple-period wigglers at PEP energies are also discussed. Comparison to a wiggler now operating in SPEAR is given

  5. Long-wavelength microinstabilities in toroidal plasmas

    International Nuclear Information System (INIS)

    Tang, W.M.; Rewoldt, G.

    1993-01-01

    Realistic kinetic toroidal eigenmode calculations have been carried out to support a proper assessment of the influence of long-wavelength microturbulence on transport in tokamak plasmas. In order to efficiently evaluate large-scale kinetic behavior extending over many rational surfaces, significant improvements have been made to a toroidal finite element code used to analyze the fully two-dimensional (r,θ) mode structures of trapped-ion and toroidal ion temperature gradient (ITG) instabilities. It is found that even at very long wavelengths, these eigenmodes exhibit a strong ballooning character with the associated radial structure relatively insensitive to ion Landau damping at the rational surfaces. In contrast to the long-accepted picture that the radial extent of trapped-ion instabilities is characterized by the ion-gyroradius-scale associated with strong localization between adjacent rational surfaces, present results demonstrate that under realistic conditions, the actual scale is governed by the large-scale variations in the equilibrium gradients. Applications to recent measurements of fluctuation properties in Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled Nucl. Fusion Res. (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 29] L-mode plasmas indicate that the theoretical trends appear consistent with spectral characteristics as well as rough heuristic estimates of the transport level. Benchmarking calculations in support of the development of a three-dimensional toroidal gyrokinetic code indicate reasonable agreement with respect to both the properties of the eigenfunctions and the magnitude of the eigenvalues during the linear phase of the simulations of toroidal ITG instabilities

  6. Wavelength-Dependent Extinction and Grain Sizes in "Dippers"

    Science.gov (United States)

    Sitko, Michael; Russell, Ray W.; Long, Zachary; Bayyari, Ammar; Assani, Korash; Grady, Carol; Lisse, Carey Michael; Marengo, Massimo; Wisniewski, John

    2018-01-01

    We have examined inter-night variability of K2-discovered "Dippers" that are not close to being viewed edge-on (as determined from previously-reported ALMA images) using the SpeX spectrograph on NASA's Infrared Telescope facility (IRTF). The three objects observed were EPIC 203850058, EPIC 205151387, and EPIC 204638512 ( = 2MASS J16042165-2130284). Using the ratio of the fluxes from 0.7-2.4 microns between two successive nights, we find that in at least two cases, the extinction increased toward shorter wavelengths. In the case of EPIC 204638512, we find that the properties of the dust differ from that seen in the diffuse interstellar medium and denser molecular clouds. However, the grain properties needed to explain the extinction does resemble those used to model the disks of many young stellar objects. The best fit to the data on EPIC 204638512 includes grains at least 500 microns in size, but lacks grains smaller than 0.25 microns. Since EPIC 204638512 is seen nearly face-on, it is possible the grains are entrained in an accretion flow that preferentially destroys the smallest grains. However, we have no indication of significant gas accretion onto the star in the form of emission lines observed in young low-mass stars. But the He I line at 1.083 microns was seen to change from night to night, and showed a P Cygni profile on one night, suggesting the gas might be outflowing from regions near the star.

  7. Planck 2013 results. XIV. Zodiacal emission

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.

    2013-01-01

    , three asteroidal dust bands, a circumsolar ring, and an Earth-trailing feature. The emissivity of the diuse cloud decreases with increasing wavelength, as expected from earlier analyses. The emissivities of the dust bands, however, decrease less rapidly, indicating that the properties of the grains......The Planck satellite provides a set of all-sky maps at nine frequencies from 30 GHz to 857 GHz. Planets, minor bodies, and diuse interplanetary dust emission (IPD) are all observed. The IPD can be separated from Galactic and other emissions because Planck views a given point on the celestial sphere...

  8. Kilonova/Macronova Emission from Compact Binary Mergers

    Directory of Open Access Journals (Sweden)

    Masaomi Tanaka

    2016-01-01

    Full Text Available We review current understanding of kilonova/macronova emission from compact binary mergers (mergers of two neutron stars or a neutron star and a black hole. Kilonova/macronova is emission powered by radioactive decays of r-process nuclei and it is one of the most promising electromagnetic counterparts of gravitational wave sources. Emission from the dynamical ejecta of ~0.01M⊙ is likely to have a luminosity of ~1040–1041 erg s−1 with a characteristic timescale of about 1 week. The spectral peak is located in red optical or near-infrared wavelengths. A subsequent accretion disk wind may provide an additional luminosity or an earlier/bluer emission if it is not absorbed by the precedent dynamical ejecta. The detection of near-infrared excess in short GRB 130603B and possible optical excess in GRB 060614 supports the concept of the kilonova/macronova scenario. At 200 Mpc distance, a typical peak brightness of kilonova/macronova with 0.01M⊙ ejecta is about 22 mag and the emission rapidly fades to >24 mag within ~10 days. Kilonova/macronova candidates can be distinguished from supernovae by (1 the faster time evolution, (2 fainter absolute magnitudes, and (3 redder colors. Since the high expansion velocity (v~0.1–0.2c is a robust outcome of compact binary mergers, the detection of smooth spectra will be the smoking gun to conclusively identify the gravitational wave source.

  9. Emissivity measurements on aeronautical alloys

    International Nuclear Information System (INIS)

    Campo, L. del; Perez-Saez, R.B.; Gonzalez-Fernandez, L.; Esquisabel, X.; Fernandez, I.; Gonzalez-Martin, P.; Tello, M.J.

    2010-01-01

    The emissivity of three Ni and Co based aeronautical alloys is analyzed in this paper. These alloys are employed in high temperature environments whenever good corrosion resistance, high temperature resistance and high strength are essential. Thus, apart from the aeronautical industry, these alloys are also used in other technological applications, as for example, aerospace, nuclear reactors, and tooling. The results in this paper extend the emissivity data for these alloys available in the literature. Emissivity dependence on the radiation wavelength (2-22 μm), sample temperature (200-650 o C) and emission angle (0-85 o ) has been investigated. In addition, the effect of surface finish and oxidation has also been taken into consideration. The data in this paper have several applications, as temperature measurement of a target by pyrometry, low observability of airplanes and thermal radiation heat transfer simulation in airplane nozzles or furnaces.

  10. Emissivity measurements on aeronautical alloys

    Energy Technology Data Exchange (ETDEWEB)

    Campo, L. del, E-mail: leire.del-campo@cnrs-orleans.f [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Perez-Saez, R.B., E-mail: raul.perez@ehu.e [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain); Gonzalez-Fernandez, L. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Esquisabel, X.; Fernandez, I. [Industria de Turbo Propulsores, S.A., Planta de Zamudio, Edificio 300, 48170 Zamudio, Bizkaia (Spain); Gonzalez-Martin, P. [Industria de Turbo Propulsores, S.A., Parque empresarial San Fernando, Avda. Castilla 2, 28830 San Fernando de Henares, Madrid (Spain); Tello, M.J. [Departamento de Fisica de la Materia Condensada, Facultad de Ciencia y Tecnologia, Universidad del Pais Vasco, Barrio Sarriena s/n, 48940 Leioa, Bizkaia (Spain); Instituto de Sintesis y Estudio de Materiales, Universidad del Pais Vasco, Apdo. 644, 48080 Bilbao (Spain)

    2010-01-21

    The emissivity of three Ni and Co based aeronautical alloys is analyzed in this paper. These alloys are employed in high temperature environments whenever good corrosion resistance, high temperature resistance and high strength are essential. Thus, apart from the aeronautical industry, these alloys are also used in other technological applications, as for example, aerospace, nuclear reactors, and tooling. The results in this paper extend the emissivity data for these alloys available in the literature. Emissivity dependence on the radiation wavelength (2-22 {mu}m), sample temperature (200-650 {sup o}C) and emission angle (0-85{sup o}) has been investigated. In addition, the effect of surface finish and oxidation has also been taken into consideration. The data in this paper have several applications, as temperature measurement of a target by pyrometry, low observability of airplanes and thermal radiation heat transfer simulation in airplane nozzles or furnaces.

  11. Measurement of amplified spontaneous emission at 200 A

    International Nuclear Information System (INIS)

    Ceglio, N.M.

    1985-01-01

    Recent interest in the production of laser radiation at soft x-ray wavelengths makes appropriate the discussion of diagnostic considerations and techniques for the measurement of same. A source of soft x-ray ASE has a number of characteristics which drive the design of diagnostic instruments: (1) the anisotropy of the ASE makes target alignment a critical part of the diagnosis, and couples collection solid angle to S/N considerations in the measurement; (2) the narrow linewidth of the amplified emission and its long wavelength put a high S/N premium on spectroscopic instrumentation of high spectral resolution and good higher-order discrimination; (3) the specialized plasma conditions required to produce gain are typically short lived, requiring time-resolved or at least time-discriminating spectroscopy; (4) the nonlinear nature of the threshold processes involved in ASE requires instrumentation of large dynamic range, broad angular acceptance, and large field of view and depth of focus. Of the many possible methods for gain verification of the x-ray source, five are discussed: (1) probe amplification; (2) spatial coherence measurement (as a function of gain length); (3) output intensity measurement (absolute measurement and nonlinear variation with gain length); (4) divergence measurement; and (5) cavity formation. In addition, recent soft x-ray laser experiments at LLNL are discussed along with descriptions of the instruments used to measure the ASE. Diagnostic design suggestions for future soft x-ray laser experiments are also presented

  12. Nanoparticle discrimination based on wavelength and lifetime-multiplexed cathodoluminescence microscopy.

    Science.gov (United States)

    Garming, Mathijs W H; Weppelman, I Gerward C; de Boer, Pascal; Martínez, Felipe Perona; Schirhagl, Romana; Hoogenboom, Jacob P; Moerland, Robert J

    2017-08-31

    Nanomaterials can be identified in high-resolution electron microscopy images using spectrally-selective cathodoluminescence. Capabilities for multiplex detection can however be limited, e.g., due to spectral overlap or availability of filters. Also, the available photon flux may be limited due to degradation under electron irradiation. Here, we demonstrate single-pass cathodoluminescence-lifetime based discrimination of different nanoparticles, using a pulsed electron beam. We also show that cathodoluminescence lifetime is a robust parameter even when the nanoparticle cathodoluminescence intensity decays over an order of magnitude. We create lifetime maps, where the lifetime of the cathodoluminescence emission is correlated with the emission intensity and secondary-electron images. The consistency of lifetime-based discrimination is verified by also correlating the emission wavelength and the lifetime of nanoparticles. Our results show how cathodoluminescence lifetime provides an additional channel of information in electron microscopy.

  13. Wavelength dependent delay in the onset of FEL tissue ablation

    International Nuclear Information System (INIS)

    Tribble, J.A.; Edwards, G.S.; Lamb, J.A.

    1995-01-01

    We are investigating the wavelength dependence of the onset of laser tissue ablation in the IR Visible and UV ranges. Toward this end, we have made simultaneous measurements of the ejected material (using a HeNe probe beam tangential to the front surface) and the residual stress transient in the tissue (using traditional piezoelectric detection behind the thin samples). For the IR studies we have used the Vanderbilt FEL and for the UV and Vis range we have used a Q-switched ND:Yag with frequency doubling and quadrupling. To satisfy the conditions of the near field limit for the detection of the stress transient, the duration of the IR FEL macropulse must be as short as possible. We have obtained macropulses as short as 100 ns using Pockels Cell technology. The recording of the signals from both the photodiode monitoring the HeNe probe beam and the acoustic detector are synchronized with the arrival of the 100 ns macropulse. With subablative intensities, the resulting stress transient is bipolar with its positive peak separated from its negative peak by 100 ns in agreement with theory. Of particular interest is the comparison of ablative results using 3 μm and 6.45 μm pulses. Both the stress transient and the ejection of material suffer a greater delay (with respect to the arrival of the 100 ns pulse) when the FEL is tuned to 3 μm as compared to 6.45 μm. A comparison of IR Vis and UV data will be discussed in terms of microscopic mechanisms governing the laser ablation process

  14. Design and implementation of a dual-wavelength intrinsic fluorescence camera system

    Science.gov (United States)

    Ortega-Martinez, Antonio; Musacchia, Joseph J.; Gutierrez-Herrera, Enoch; Wang, Ying; Franco, Walfre

    2017-03-01

    Intrinsic UV fluorescence imaging is a technique that permits the observation of spatial differences in emitted fluorescence. It relies on the fluorescence produced by the innate fluorophores in the sample, and thus can be used for marker-less in-vivo assessment of tissue. It has been studied as a tool for the study of the skin, specifically for the classification of lesions, the delimitation of lesion borders and the study of wound healing, among others. In its most basic setup, a sample is excited with a narrow-band UV light source and the resulting fluorescence is imaged with a UV sensitive camera filtered to the emission wavelength of interest. By carefully selecting the excitation/emission pair, we can observe changes in fluorescence associated with physiological processes. One of the main drawbacks of this simple setup is the inability to observe more than a single excitation/emission pair at the same time, as some phenomena are better studied when two or more different pairs are studied simultaneously. In this work, we describe the design and the hardware and software implementation of a dual wavelength portable UV fluorescence imaging system. Its main components are an UV camera, a dual wavelength UV LED illuminator (295 and 345 nm) and two different emission filters (345 and 390 nm) that can be swapped by a mechanical filter wheel. The system is operated using a laptop computer and custom software that performs basic pre-processing to improve the image. The system was designed to allow us to image fluorescent peaks of tryptophan and collagen cross links in order to study wound healing progression.

  15. Plasmonic distributed feedback lasers at telecommunications wavelengths.

    Science.gov (United States)

    Marell, Milan J H; Smalbrugge, Barry; Geluk, Erik Jan; van Veldhoven, Peter J; Barcones, Beatrix; Koopmans, Bert; Nötzel, Richard; Smit, Meint K; Hill, Martin T

    2011-08-01

    We investigate electrically pumped, distributed feedback (DFB) lasers, based on gap-plasmon mode metallic waveguides. The waveguides have nano-scale widths below the diffraction limit and incorporate vertical groove Bragg gratings. These metallic Bragg gratings provide a broad bandwidth stop band (~500 nm) with grating coupling coefficients of over 5000/cm. A strong suppression of spontaneous emission occurs in these Bragg grating cavities, over the stop band frequencies. This strong suppression manifests itself in our experimental results as a near absence of spontaneous emission and significantly reduced lasing thresholds when compared to similar length Fabry-Pérot waveguide cavities. Furthermore, the reduced threshold pumping requirements permits us to show strong line narrowing and super linear light current curves for these plasmon mode devices even at room temperature.

  16. Tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal structure

    International Nuclear Information System (INIS)

    Huang, Wenbin; Pu, Donglin; Qiao, Wen; Wan, Wenqiang; Liu, Yanhua; Ye, Yan; Wu, Shaolong; Chen, Linsen

    2016-01-01

    A continuously tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal cavity is demonstrated. The triangular-lattice resonator was initially fabricated through multiple interference exposure and was then replicated into a low refractive index polymer via UV-nanoimprinting. The blend of a blue-emitting conjugated polymer and a red-emitting one was used as the gain medium. Three periods in the scalene triangular-lattice structure yield stable tri-wavelength laser emission (625.5 nm, 617.4 nm and 614.3 nm) in six different directions. A uniformly aligned liquid crystal (LC) layer was incorporated into the cavity as the top cladding layer. Upon heating, the orientation of LC molecules and thus the effective refractive index of the lasing mode changes which continuously shifts the lasing wavelength. A maximum tuning range of 12.2 nm was observed for the lasing mode at 625.5 nm. This tunable tri-wavelength polymer laser is simple constructed and cost-effective. It may find application in the fields of biosensors and photonic integrated circuits. (paper)

  17. High-efficiency and low-loss gallium nitride dielectric metasurfaces for nanophotonics at visible wavelengths

    Science.gov (United States)

    Emani, Naresh Kumar; Khaidarov, Egor; Paniagua-Domínguez, Ramón; Fu, Yuan Hsing; Valuckas, Vytautas; Lu, Shunpeng; Zhang, Xueliang; Tan, Swee Tiam; Demir, Hilmi Volkan; Kuznetsov, Arseniy I.

    2017-11-01

    The dielectric nanophotonics research community is currently exploring transparent material platforms (e.g., TiO2, Si3N4, and GaP) to realize compact high efficiency optical devices at visible wavelengths. Efficient visible-light operation is key to integrating atomic quantum systems for future quantum computing. Gallium nitride (GaN), a III-V semiconductor which is highly transparent at visible wavelengths, is a promising material choice for active, nonlinear, and quantum nanophotonic applications. Here, we present the design and experimental realization of high efficiency beam deflecting and polarization beam splitting metasurfaces consisting of GaN nanostructures etched on the GaN epitaxial substrate itself. We demonstrate a polarization insensitive beam deflecting metasurface with 64% and 90% absolute and relative efficiencies. Further, a polarization beam splitter with an extinction ratio of 8.6/1 (6.2/1) and a transmission of 73% (67%) for p-polarization (s-polarization) is implemented to demonstrate the broad functionality that can be realized on this platform. The metasurfaces in our work exhibit a broadband response in the blue wavelength range of 430-470 nm. This nanophotonic platform of GaN shows the way to off- and on-chip nonlinear and quantum photonic devices working efficiently at blue emission wavelengths common to many atomic quantum emitters such as Ca+ and Sr+ ions.

  18. Short wavelengths filtering properties of sunglasses on the Canadian market: are we protected?

    Science.gov (United States)

    Trang, Nataly; Lalonde, Gilles; Dubé, Yolande; Bourgault, Serge; Rochette, Patrick J

    2018-04-01

    Exposure to solar radiation is a risk factor for multiple ocular pathologies. Ultraviolet (UV) radiation is involved in ocular diseases, including pterygium, ocular surface squamous neoplasia, and cataracts. High-energy visible light (HEV) is associated with age-related macular degeneration. Ocular protection against solar radiation seems essential to protect our eyes against the adverse effects of those harmful rays. Australia, New Zealand, Europe, and the United States are the only regions with mandatory standards for UV transmission for sunglasses. Adherence to Canadian standards by sunglasses manufacturers is not mandatory. In this study, we evaluated the UV and visible transmission of sunglasses in the Canadian market to test their compliance with Canadian standards. The transmittance of 207 pairs of sunglasses, divided in 3 categories according to their price range, was measured. We show that close to 100% of the sunglasses tested respect the Canadian standards. The average HEV transmittance is around 10%, regardless the price range. Our study demonstrated that even if following Canadian standards is optional, most sunglasses sold on the Canadian market follow national and international standards. We also found that sunglasses filter around 90% of HEV. With the recent findings on the potential effects of HEV in retinal pathologies, we can ask whether this filtering capacity is sufficient to protect eyes from harmful HEV light. More work needs to be done to determine acceptable HEV light transmission limits to the existing Canadian standards. Copyright © 2018 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.

  19. Low- and high-mode separation of short wavelength turbulence in dithering Wendelstein 7-AS plasmas

    DEFF Research Database (Denmark)

    Basse, N.P.; Zoletnik, S.; Saffman, M.

    2002-01-01

    In this article measurements of small scale electron density fluctuations in dithering high confinement (H)-mode plasmas obtained by collective scattering of infrared light are presented. A scan of the fluctuation wavenumber was made in a series of similar discharges in the Wendelstein 7-AS (W7-A...

  20. Destruction of pesticides and their formulations in water using short wavelength UV light

    International Nuclear Information System (INIS)

    Peterson, D.; Watson, D.; Winterlin, W.

    1990-01-01

    The presence of toxic materials in surface and ground water is a problem of growing significance. Increasingly, toxic anthropogenic chemicals are being detected in water supplies resulting in public concern and regulatory restrictions. Clearly, there is a need to develop methods to decontaminate not only drinking water supplies, but also the sources of contamination. Decontamination of water poses economic and logistical challenges since the pollutants are usually present in low concentrations and distributed over a wide area. A number of strategies have been proposed and tested to destroy toxic materials in water. In this study, the authors examined the effectiveness of a photoreactor equipped with a high pressure mercury vapor lamp for the destruction of three pesticides and the inert ingredient m-xylene in water. Captan, chlordane, PCNB, and m-xylene in aqueous solutions were selected as model compounds for this study based on their use, resistance to UV degradation, and potential presence in formulated pesticide materials. The factors that influence the performance of the system were investigated

  1. Refractive Index Measurement within a Photonic Crystal Fibre Based on Short Wavelength Diffraction

    Directory of Open Access Journals (Sweden)

    Nathaniel Groothoff

    2007-10-01

    Full Text Available A new class of refractive index sensors using solid core photonic crystal fibres isdemonstrated. Coherent scattering at the cladding lattice is used to optically characterizematerials inserted into the fibre holes. The liquid to solid phase transition of water uponfreezing to ice 1h is characterized by determining the refractive index.

  2. A System for Compressive Spectral and Polarization Imaging at Short Wave Infrared (SWIR) Wavelengths

    Science.gov (United States)

    2017-10-18

    UV -­‐ VIS -­‐IR   60mm   Apo   Macro  lens   Jenoptik-­‐Inc   $5,817.36   IR... VIS /NIR Compressive Spectral Imager”, Proceedings of IEEE International Conference on Image Processing (ICIP ’15), Quebec City, Canada, (September...imaging   system   will   lead   to   a   wide-­‐band   VIS -­‐NIR-­‐SWIR   compressive  spectral  and  polarimetric

  3. Short-wavelength and three-dimensional instability evolution in National Ignition Facility ignition capsule designs

    International Nuclear Information System (INIS)

    Clark, D. S.; Haan, S. W.; Cook, A. W.; Edwards, M. J.; Hammel, B. A.; Koning, J. M.; Marinak, M. M.

    2011-01-01

    Ignition capsule designs for the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 443, 2841 (2004)] have continued to evolve in light of improved physical data inputs, improving simulation techniques, and, most recently, experimental data from a growing number of NIF sub-ignition experiments. This paper summarizes a number of recent changes to the cryogenic capsule design and some of our latest techniques in simulating its performance. Specifically, recent experimental results indicated harder x-ray drive spectra in NIF hohlraums than were predicted and used in previous capsule optimization studies. To accommodate this harder drive spectrum, a series of high-resolution 2-D simulations, resolving Legendre mode numbers as high as 2000, were run and the germanium dopant concentration and ablator shell thicknesses re-optimized accordingly. Simultaneously, the possibility of cooperative or nonlinear interaction between neighboring ablator surface defects has motivated a series of fully 3-D simulations run with the massively parallel HYDRA code. These last simulations include perturbations seeded on all capsule interfaces and can use actual measured shell surfaces as initial conditions. 3-D simulations resolving Legendre modes up to 200 on large capsule sectors have run through ignition and burn, and higher resolution simulations resolving as high as mode 1200 have been run to benchmark high-resolution 2-D runs. Finally, highly resolved 3-D simulations have also been run of the jet-type perturbation caused by the fill tube fitted to the capsule. These 3-D simulations compare well with the more typical 2-D simulations used in assessing the fill tube's impact on ignition. Coupled with the latest experimental inputs from NIF, our improving simulation capability yields a fuller and more accurate picture of NIF ignition capsule performance.

  4. Excitation of short wavelength Alfven oscillations by high energy ions in tokamak

    International Nuclear Information System (INIS)

    Beasley, C.O. Jr.; Lominadze, J.G.; Mikhailovskii, A.B.

    1975-08-01

    The excitation of Alfven waves by fast untrapped ions in axisymmetric tokamaks is described by the dispersion relation epsilon 11 - c 2 k/sub parallel bars/ 2 /ω 2 = 0. Using this relation a new class of instability connected with the excitation of Alfven oscillations is described. (U.S.)

  5. Short wavelength laser calculations for electron pumping in neon-like krypton (Kr XXVII)

    Science.gov (United States)

    Feldman, U.; Bhatia, A. K.; Suckewer, S.

    1983-01-01

    Calculations of electron impact collision strengths and spontaneous radiative decay rates are made for neon-like krypton (Kr XXVII) for the 2s2 2p6, 2s2 2p5 3s, 2s2 2p5 3p, and 2s2 2p5 3d configurations. From these atomic data, the level populations as a function of the electron density are calculated at two temperatures, 1 x 10 to the 7th K and 3 x 10 to the 7th K. An analysis of level populations reveals that a volume of krypton in which a significant number of the ions are in the Kr XXVII degree of ionization can produce a significant gain in transition between the 2s2 2p5 3s and 2s2 2p5 3p configurations. At an electron density of 1 x 10 to the 19th/cu cm the plasma length has to be of the order of 1 m; at a density of 1 x 10 to the 21st/cu cm the length is reduced to approximately 0.5 cm; and at an electron density of 1 x 10 to the 22nd/cu cm the length of the plasma is further reduced to approximately 1 mm.

  6. Short-wavelength ablation of polymers in the high-fluence regime

    Czech Academy of Sciences Publication Activity Database

    Liberatore, Chiara; Mann, K.; Müller, M.; Pina, L.; Juha, Libor; Vyšín, Luděk; Rocca, J.J.; Endo, Akira; Mocek, Tomáš

    T161, MAY (2014), "014066-1"-"014066-4" ISSN 0031-8949 R&D Projects: GA MŠk ED2.1.00/01.0027; GA MŠk EE2.3.20.0143 Grant - others:HILASE(XE) CZ.1.05/2.1.00/01.0027; OP VK 6(XE) CZ.1.07/2.3.00/20.0143 Institutional support: RVO:68378271 Keywords : extreme ultraviolet * soft x-ray * ablation * polymers Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.126, year: 2014

  7. Experimental study of laser-plasma interaction physics with short laser wavelength

    International Nuclear Information System (INIS)

    Labaune, C.; Amiranoff, F.; Fabre, E.; Matthieussent, G.; Rousseaux, C.; Baton, S.

    1989-01-01

    Many non-linear processes can affect laser-plasma coupling in fusion experiments. The interaction processes of interest involve three or more waves, including the incident electromagnetic wave and various selections of electromagnetic, electrostatic and accoustic waves. Whenever plasma waves are involved (stimulated Raman scattering, two-plasmon decay instability, parametric decay instability and others), energetic electrons are created through the various damping processes of these waves: these energetic electrons in turn deleteriously affect the compression phase in laser fusion experiments through pre-heating of the fuel core. Some parametric processes lead primarily to loss of incident laser energy (stimulated Brillouin scattering) while others, such as filamentation, lead to strongly enhanced local laser intensities through the focusing of part (or all) of the laser beam into filaments of very small dimensions with a concomitant expulsion of the plasma out of these regions. So filamentation destroys the uniformity of energy deposition in the plasma and prevents high compression efficiency of the target. These interaction effects are typically of parametric nature, with their thresholds and growth rates depending critically on plasma scale lengths. Since these scale lengths increase with available laser energy and since millimeter sized plasmas are expected from reactor targets which will be used in direct drive implosion experiments, a good understanding of these processes and their saturation mechanisms becomes imperative. We report here the results on absolute energy measurements and time-resolved spectra of SRS and SBS obtained in various types of plasmas where the major changes were the inhomogeneity scale lengths. (author) 7 refs., 7 figs

  8. Observing Structure and Motion in Molecules with Ultrafast Strong Field and Short Wavelength Laser Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Bucksbaum, Philip H

    2011-04-13

    The term "molecular movie" has come to describe efforts to track and record Angstrom-scale coherent atomic and electronic motion in a molecule. The relevant time scales for this range cover several orders of magnitude, from sub-femtosecond motion associated with electron-electron correlations, to 100-fs internal vibrations, to multi-picosecond motion associated with the dispersion and quantum revivals of molecular reorientation. Conventional methods of cinematography do not work well in this ultrafast and ultrasmall regime, but stroboscopic "pump and probe" techniques can reveal this motion with high fidelity. This talk will describe some of the methods and recent progress in exciting and controlling this motion, using both laboratory lasers and the SLAC Linac Coherent Light Source x-ray free electron laser, and will further try to relate the date to the goal of molecular movies.

  9. Conductors, semiconductors and insulators irradiated with short-wavelength free-electron laser

    Czech Academy of Sciences Publication Activity Database

    Krzywinski, J.; Sobierajski, R.; Jurek, M.; Nietubyc, R.; Pelka, J. B.; Juha, Libor; Bittner, Michal; Létal, V.; Vorlíček, Vladimír; Andrejczuk, A.; Feldhaus, J.; Keitel, B.; Saldin, E.; Schneidmiller, E.A.; Treusch, R.; Yurkov, M. V.

    2007-01-01

    Roč. 101, č. 4 (2007), 043107/1-043107/4 ISSN 0021-8979 R&D Projects: GA MŠk 1P04LA235; GA MŠk LC510; GA MŠk(CZ) LC528 Institutional research plan: CEZ:AV0Z10100523 Keywords : free-electron laser * extreme ultraviolet * ablation * laser-matter interaction Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.171, year: 2007

  10. Steady-state pulses and superradiance in short-wavelength, swept-gain amplifiers

    International Nuclear Information System (INIS)

    Bonifacio, R.; Hopf, F.A.; Meystre, P.; Scully, M.O.

    1975-01-01

    The steady-state behavior of amplifiers in which the excitation is swept at the speed of light is discussed in the semiclassical approximation. In the present work the case where the decay time of the population is comparable to that of the polarization is examined. Pulse propagation is shown to obey a generalized sine-Gordon equation which contains the effects of atomic relaxations. The analytical expression of the steady-state pulses (SSP) gives two threshold conditions. In the region of limited gain the SSP is a broad pulse with small area which can be obtained by small signal theory. In the second region of high gain the SSP is the superradiant π pulse. Its pulse power is not limited as in usual superradiant theory because, as is shown, for a swept excitation the cooperation-length limit does not exist

  11. Multi-wavelength study of infrared galaxies

    International Nuclear Information System (INIS)

    Marcillac, Delphine

    2005-01-01

    This thesis deals with a panchromatic study of luminous infrared galaxies (LIRGs) detected at 15 microns by ISOCAM (camera aboard ISO) and at 24 microns by MIPS (camera aboard the recently launched Spitzer satellite). These galaxies are today considered to be the Rosetta Stone of galaxy evolution since they are found to be far more numerous at high redshift and it is thought that a large part of stars seen in the local universe are born in such phases. The first part of this thesis presents a new study dedicated to dust emission of distant LIRGs in the mid-infrared range. Their dust emission has been compared to those of a local sample of LIRGs in addition to the prediction of several spectral energy distributions (SEDs) built on data available in the local universe. It has been shown that distant and local LIRGs present similar mid infrared spectral energy distribution: similar PAH bumps are detected in both local and distant LIRGs, however distant LIRGs show evidence of a stronger silicate absorption at 10 microns associated silicate grains. It also shows that distant LIRG mid infrared emission can be used together with local SEDs in order to estimate the total infrared luminosity. The second part of this thesis is dedicated to the burst of star formation and to the recent star formation history of these galaxies, which is responsible for the dust emission. This study was done thanks to a combination of high resolution spectra (R=2000 in the rest frame) obtained at VLT/FORS2 and the stellar population synthesis models called GALAXEV (Bruzual and Charlot, 2003). It has been shown that the burst of star formation has a duration of about 0.1 Gyear. About 10 % of the stellar content is formed during this burst of star formation. (author) [fr

  12. POLAMI: Polarimetric Monitoring of Active Galactic Nuclei at Millimetre Wavelengths - III. Characterization of total flux density and polarization variability of relativistic jets

    Science.gov (United States)

    Agudo, Iván; Thum, Clemens; Ramakrishnan, Venkatessh; Molina, Sol N.; Casadio, Carolina; Gómez, José L.

    2018-01-01

    We report on the first results of the POLAMI (Polarimetric Monitoring of AGNs with Millimetre Wavelengths) programme, a simultaneous 3.5 and 1.3 mm full-Stokes-polarization monitoring of a sample of 36 of the brightest active galactic nuclei in the northern sky with the IRAM 30 m telescope. Through a systematic statistical study of data taken from 2006 October (from 2009 December for the case of the 1.3 mm observations) to 2014 August, we characterize the variability of the total flux density and linear polarization. We find that all sources in the sample are highly variable in total flux density at both 3.5 and 1.3 mm, as well as in spectral index, which (except in particularly prominent flares) is found to be optically thin between these two wavelengths. The total flux-density variability at 1.3 mm is found, in general, to be faster, and to have larger fractional amplitude and flatter power-spectral-density slopes than at 3.5 mm. The polarization degree is on average larger at 1.3 mm than at 3.5 mm, by a factor of 2.6. The variability of linear polarization degree is faster and has higher fractional amplitude than for total flux density, with the typical time-scales during prominent polarization peaks being significantly faster at 1.3 mm than at 3.5 mm. The polarization angle at both 3.5 and 1.3 mm is highly variable. Most of the sources show one or two excursions of >180° on time-scales from a few weeks to about a year during the course of our observations. The 3.5 and 1.3 mm polarization angle evolution follows each other rather well, although the 1.3 mm data show a clear preference to more prominent variability on the short time-scales, i.e. weeks. The data are compatible with multizone models of conical jets involving smaller emission regions for the shortest-wavelength emitting sites. Such smaller emitting regions should also be more efficient in energising particle populations, as implied by the coherent evolution of the spectral index and the total flux

  13. Pulsar Emission: Is It All Relative?

    Science.gov (United States)

    Harding, Alice K.

    2004-01-01

    Thirty-five years after the discovery of pulsars, we still do not understand the fundamentals of their pulsed emission at any wavelength. The fact that even detailed pulse profiles cannot identlfy the origin of the emission in a magnetosphere that extends fiom the neutron star surface to plasma moving at relativistic speeds near the light cylinder compounds the problem. I will discuss the role of special and general relativistic effects on pulsar emission, fiom inertial frame-dragging near the stellar surface to aberration, time-of-flight and retardation of the magnetic field near the light cylinder. Understanding how these effects determine what we observe at different wavelengths is critical to unraveling the emission physics.

  14. Long wavelength infrared radiation thermometry for non-contact temperature measurements in gas turbines

    Science.gov (United States)

    Manara, J.; Zipf, M.; Stark, T.; Arduini, M.; Ebert, H.-P.; Tutschke, A.; Hallam, A.; Hanspal, J.; Langley, M.; Hodge, D.; Hartmann, J.

    2017-01-01

    The objective of the EU project "Sensors Towards Advanced Monitoring and Control of Gas Turbine Engines (acronym STARGATE)" is the development of a suite of advanced sensors, instrumentation and related systems in order to contribute to the developing of the next generation of green and efficient gas turbine engines. One work package of the project deals with the design and development of a long wavelength infrared (LWIR) radiation thermometer for the non-contact measurement of the surface temperature of thermal barrier coatings (TBCs) during the operation of gas turbine engines. For opaque surfaces (e.g. metals or superalloys) radiation thermometers which are sensitive in the near or short wavelength infrared are used as state-of-the-art method for non-contact temperature measurements. But this is not suitable for oxide ceramic based TBCs (e.g. partially yttria stabilized zirconia) as oxide ceramics are semi-transparent in the near and short wavelength infrared spectral region. Fortunately the applied ceramic materials are non-transparent in the long wavelength infrared and additionally exhibit a high emittance in this wavelength region. Therefore, a LWIR pyrometer can be used for non-contact temperature measurements of the surfaces of TBCs as such pyrometers overcome the described limitation of existing techniques. For performing non-contact temperature measurements in gas turbines one has to know the infrared-optical properties of the applied TBCs as well as of the hot combustion gas in order to properly analyse the measurement data. For reaching a low uncertainty on the one hand the emittance of the TBC should be high (>0.9) in order to reduce reflections from the hot surrounding and on the other hand the absorbance of the hot combustion gas should be low (<0.1) in order to decrease the influence of the gas on the measured signal. This paper presents the results of the work performed by the authors with focus on the implementation of the LWIR pyrometer and the

  15. Short communication: Use of a portable, automated, open-circuit gas quantification system and the sulfur hexafluoride tracer technique for measuring enteric methane emissions in Holstein cows fed ad libitum or restricted.

    Science.gov (United States)

    Dorich, C D; Varner, R K; Pereira, A B D; Martineau, R; Soder, K J; Brito, A F

    2015-04-01

    The objective of this study was to measure enteric CH4 emissions using a new portable automated open-circuit gas quantification system (GQS) and the sulfur hexafluoride tracer technique (SF6) in midlactation Holstein cows housed in a tiestall barn. Sixteen cows averaging 176 ± 34 d in milk, 40.7 ± 6.1 kg of milk yield, and 685 ± 49 kg of body weight were randomly assigned to 1 out of 2 treatments according to a crossover design. Treatments were (1) ad libitum (adjusted daily to yield 10% orts) and (2) restricted feed intake [set to restrict feed by 10% of baseline dry matter intake (DMI)]. Each experimental period lasted 22d, with 14 d for treatment adaptation and 8d for data and sample collection. A common diet was fed to the cows as a total mixed ration and contained 40.4% corn silage, 11.2% grass-legume haylage, and 48.4% concentrate on a dry matter basis. Spot 5-min measurements using the GQS were taken twice daily with a 12-h interval between sampling and sampling times advanced 2h daily to account for diurnal variation in CH4 emissions. Canisters for the SF6 method were sampled twice daily before milking with 4 local background gas canisters inside the barn analyzed for background gas concentrations. Enteric CH4 emissions were not affected by treatments and averaged 472 and 458 g/d (standard error of the mean = 18 g/d) for ad libitum and restricted intake treatments, respectively (data not shown). The GQS appears to be a reliable method because of the relatively low coefficients of variation (ranging from 14.1 to 22.4%) for CH4 emissions and a moderate relationship (coefficient of determination = 0.42) between CH4 emissions and DMI. The SF6 resulted in large coefficients of variation (ranging from 16.0 to 111%) for CH4 emissions and a poor relationship (coefficient of determination = 0.17) between CH4 emissions and DMI, likely because of limited barn ventilation and high background gas concentration. Research with improved barn ventilation systems or

  16. Is it efficient to co-compost and co-vermicompost green waste with biochar and/or clay to reduce CO2 emissions? A short-term laboratory experiment on (vermi)composts with additives.

    Science.gov (United States)

    Barthod, Justine; Rumpel, Cornélia; Paradelo, Remigio; Dignac, Marie-France

    2016-04-01

    Intensive farming practices can lead to a depletion of soil organic matter, negatively impacting important soil properties such as structural stability, fertility and C storage. The addition of organic amendments such as compost and vermicompost, rich in carbon, helps maintaining soil organic matter levels or restoring degraded soils. Composting and vermicomposting are based on stabilization of organic matter through the mineralization of easily decomposable organic matter compounds, therefore releasing greenhouse gases, including CO2. The aim of this study was to evaluate the global potential reduction of such emissions by the use of additives (2:1 clay and/or biochar): during (vermi)composting processes and after use of the final products as soil amendments. We hypothesized that the interactions between the additives and organic matter may lead to carbon stabilization and that such interactions may be enhanced by the presence of worms (Eisenia). We added in different proportions clay (25% or 50%), biochar (10%) and a mixture of biochar (10%) with clay (25%) to pre-composted green waste. The CO2 emissions of the composting and vermicomposting processes were measured during 21 days. After that, the amendments were added to a loamy cambisol soil and the CO2 emissions were monitored during 30 days of a laboratory experiment. The most efficient treatments in terms of reducing global CO2 emissions were the co-vermicomposting process with 25% clay followed by co-composting with 50% clay and with 10% biochar plus 25% clay. In this treatment (vermicompost with 25% clay), the carbon emissions were decreased by up to 44% compared to regular compost. Addition of biochar reduced CO2 emissions only during composting. Co-composting with biochar could be a promising avenue to limit global CO2 emissions whereas in presence of worms clay additions are better suited. These findings suggest that the presence of worms increased the formation of organo-mineral associations and thus C

  17. Emissions Trading

    NARCIS (Netherlands)

    Woerdman, Edwin; Backhaus, Juergen

    2014-01-01

    Emissions trading is a market-based instrument to achieve environmental targets in a cost-effective way by allowing legal entities to buy and sell emission rights. The current international dissemination and intended linking of emissions trading schemes underlines the growing relevance of this

  18. Certain features of FELs with short bunches

    International Nuclear Information System (INIS)

    Lebedev, A.N.

    2006-01-01

    The report is devoted to physics of free electron lasers operating in the short-wave domain where the bunch length could be less than the undulator length in the proper frame. Then the current component of the signal is locked within the bunch as in a cavity, while the electromagnetic component propagates freely. In contrast with gyrotrons where this regime can be of interest only for wavelengths comparable with the bunch length, we consider short waves in a bunch of arbitrary profile. Both amplification of an external harmonic signal and SASE regime, i.e. selective amplification of proper noises, are investigated

  19. Ultra-short silicon MMI duplexer

    Science.gov (United States)

    Yi, Huaxiang; Huang, Yawen; Wang, Xingjun; Zhou, Zhiping

    2012-11-01

    The fiber-to-the-home (FTTH) systems are growing fast these days, where two different wavelengths are used for upstream and downstream traffic, typically 1310nm and 1490nm. The duplexers are the key elements to separate these wavelengths into different path in central offices (CO) and optical network unit (ONU) in passive optical network (PON). Multimode interference (MMI) has some benefits to be a duplexer including large fabrication tolerance, low-temperature dependence, and low-polarization dependence, but its size is too large to integrate in conventional case. Based on the silicon photonics platform, ultra-short silicon MMI duplexer was demonstrated to separate the 1310nm and 1490nm lights. By studying the theory of self-image phenomena in MMI, the first order images are adopted in order to keep the device short. A cascaded MMI structure was investigated to implement the wavelength splitting, where both the light of 1310nm and 1490nm was input from the same port, and the 1490nm light was coupling cross the first MMI and output at the cross-port in the device while the 1310nm light was coupling through the first and second MMI and output at the bar-port in the device. The experiment was carried on with the SOI wafer of 340nm top silicon. The cascaded MMI was investigated to fold the length of the duplexer as short as 117μm with the extinct ratio over 10dB.

  20. Optimal Fluorescence Waveband Determination for Detecting Defective Cherry Tomatoes Using a Fluorescence Excitation-Emission Matrix

    Directory of Open Access Journals (Sweden)

    In-Suck Baek

    2014-11-01

    Full Text Available A multi-spectral fluorescence imaging technique was used to detect defective cherry tomatoes. The fluorescence excitation and emission matrix was used to measure for defects, sound surface and stem areas to determine the optimal fluorescence excitation and emission wavelengths for discrimination. Two-way ANOVA revealed the optimal excitation wavelength for detecting defect areas was 410 nm. Principal component analysis (PCA was applied to the fluorescence emission spectra of all regions at 410 nm excitation to determine the emission wavelengths for defect detection. The major emission wavelengths were 688 nm and 506 nm for the detection. Fluorescence images combined with the determined emission wavebands demonstrated the feasibility of detecting defective cherry tomatoes with >98% accuracy. Multi-spectral fluorescence imaging has potential utility in non-destructive quality sorting of cherry tomatoes.