WorldWideScience

Sample records for strong light emission

  1. Engineering light emission of two-dimensional materials in both the weak and strong coupling regimes

    Science.gov (United States)

    Brotons-Gisbert, Mauro; Martínez-Pastor, Juan P.; Ballesteros, Guillem C.; Gerardot, Brian D.; Sánchez-Royo, Juan F.

    2018-01-01

    Two-dimensional (2D) materials have promising applications in optoelectronics, photonics, and quantum technologies. However, their intrinsically low light absorption limits their performance, and potential devices must be accurately engineered for optimal operation. Here, we apply a transfer matrix-based source-term method to optimize light absorption and emission in 2D materials and related devices in weak and strong coupling regimes. The implemented analytical model accurately accounts for experimental results reported for representative 2D materials such as graphene and MoS2. The model has been extended to propose structures to optimize light emission by exciton recombination in MoS2 single layers, light extraction from arbitrarily oriented dipole monolayers, and single-photon emission in 2D materials. Also, it has been successfully applied to retrieve exciton-cavity interaction parameters from MoS2 microcavity experiments. The present model appears as a powerful and versatile tool for the design of new optoelectronic devices based on 2D semiconductors such as quantum light sources and polariton lasers.

  2. Laser based imaging of time depending microscopic scenes with strong light emission

    Science.gov (United States)

    Hahlweg, Cornelius; Wilhelm, Eugen; Rothe, Hendrik

    2011-10-01

    Investigating volume scatterometry methods based on short range LIDAR devices for non-static objects we achieved interesting results aside the intended micro-LIDAR: the high speed camera recording of the illuminated scene of an exploding wire -intended for Doppler LIDAR tests - delivered a very effective method of observing details of objects with extremely strong light emission. As a side effect a schlieren movie is gathered without any special effort. The fact that microscopic features of short time processes with high emission and material flow might be imaged without endangering valuable equipment makes this technique at least as interesting as the intended one. So we decided to present our results - including latest video and photo material - instead of a more theoretical paper on our progress concerning the primary goal.

  3. Strongly transverse-electric-polarized emission from deep ultraviolet AlGaN quantum well light emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Reich, Christoph, E-mail: Christoph.Reich@tu-berlin.de; Guttmann, Martin; Wernicke, Tim; Mehnke, Frank; Kuhn, Christian [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, Berlin 10623 (Germany); Feneberg, Martin; Goldhahn, Rüdiger [Institut für Experimentelle Physik, Otto-von-Guericke-Universität, Universitätsplatz 2, Magdeburg 39106 (Germany); Rass, Jens; Kneissl, Michael [Institut für Festkörperphysik, Technische Universität Berlin, Hardenbergstr. 36, Berlin 10623 (Germany); Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, Berlin 12489 (Germany); Lapeyrade, Mickael; Einfeldt, Sven; Knauer, Arne; Kueller, Viola; Weyers, Markus [Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Gustav-Kirchhoff-Str. 4, Berlin 12489 (Germany)

    2015-10-05

    The optical polarization of emission from ultraviolet (UV) light emitting diodes (LEDs) based on (0001)-oriented Al{sub x}Ga{sub 1−x}N multiple quantum wells (MQWs) has been studied by simulations and electroluminescence measurements. With increasing aluminum mole fraction in the quantum well x, the in-plane intensity of transverse-electric (TE) polarized light decreases relative to that of the transverse-magnetic polarized light, attributed to a reordering of the valence bands in Al{sub x}Ga{sub 1−x}N. Using k ⋅ p theoretical model calculations, the AlGaN MQW active region design has been optimized, yielding increased TE polarization and thus higher extraction efficiency for bottom-emitting LEDs in the deep UV spectral range. Using (i) narrow quantum wells, (ii) barriers with high aluminum mole fractions, and (iii) compressive growth on patterned aluminum nitride sapphire templates, strongly TE-polarized emission was observed at wavelengths as short as 239 nm.

  4. Spontaneous emission spectra and quantum light-matter interactions from a strongly coupled quantum dot metal-nanoparticle system

    DEFF Research Database (Denmark)

    Van Vlack, C.; Kristensen, Philip Trøst; Hughes, S.

    2012-01-01

    the dot to the detector, we demonstrate that the strong-coupling regime should be observable in the far-field spontaneous emission spectrum, even at room temperature. The vacuum-induced emission spectra show that the usual vacuum Rabi doublet becomes a rich spectral triplet or quartet with two of the four...

  5. Strong blue and white photoluminescence emission of BaZrO{sub 3} undoped and lanthanide doped phosphor for light emitting diodes application

    Energy Technology Data Exchange (ETDEWEB)

    Romero, V.H. [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); De la Rosa, E., E-mail: elder@cio.mx [Centro de Investigaciones en Optica, A. P. 1-948, Leon Gto., 37160 (Mexico); Salas, P. [Centro de Fisica Aplicada y Tecnologia Avanzada, Universidad Nacional Autonoma de Mexico, A.P. 1-1010, Queretaro, Qro. 76000 (Mexico); Velazquez-Salazar, J.J. [Department of Physics and Astronomy, The University of Texas at San Antonio One UTSA Circle, San Antonio TX 78249 (United States)

    2012-12-15

    In this paper, we report the obtained strong broadband blue photoluminescence (PL) emission centered at 427 nm for undoped BaZrO{sub 3} observed after 266 nm excitation of submicron crystals prepared by hydrothermal/calcinations method. This emission is enhanced with the introduction of Tm{sup 3+} ions and is stronger than the characteristic PL blue emission of such lanthanide. The proposed mechanism of relaxation for host lattice emission is based on the presence of oxygen vacancies produced during the synthesis process and the charge compensation due to the difference in the electron valence between dopant and substituted ion in the host. Brilliant white light emission with a color coordinate of (x=0.29, y=0.32) was observed by combining the blue PL emission from the host with the green and red PL emission from Tb{sup 3+} and Eu{sup 3+} ions, respectively. The color coordinate can be tuned by changing the ratio between blue, green and red band by changing the concentration of lanthanides. - Graphical abstract: Strong blue emission from undoped BaZrO{sub 3} phosphor and white light emission by doping with Tb{sup 3+} (green) and Eu{sup 3+} (red) after 266 nm excitation. Highlights: Black-Right-Pointing-Pointer Blue emission from BaZrO{sub 3} phosphor. Black-Right-Pointing-Pointer Blue emission enhanced with Tm{sup 3+}. Black-Right-Pointing-Pointer White light from BaZrO{sup 3+} phosphor.

  6. Strong enhancement of emission efficiency in GaN light-emitting diodes by plasmon-coupled light amplification of graphene

    Science.gov (United States)

    Kim, Jong Min; Kim, Sung; Hwang, Sung Won; Kim, Chang Oh; Shin, Dong Hee; Kim, Ju Hwan; Jang, Chan Wook; Kang, Soo Seok; Hwang, Euyheon; Choi, Suk-Ho; El-Gohary, Sherif H.; Byun, Kyung Min

    2018-02-01

    Recently, we have demonstrated that excitation of plasmon-polaritons in a mechanically-derived graphene sheet on the top of a ZnO semiconductor considerably enhances its light emission efficiency. If this scheme is also applied to device structures, it is then expected that the energy efficiency of light-emitting diodes (LEDs) increases substantially and the commercial potential will be enormous. Here, we report that the plasmon-induced light coupling amplifies emitted light by ∼1.6 times in doped large-area chemical-vapor-deposition-grown graphene, which is useful for practical applications. This coupling behavior also appears in GaN-based LEDs. With AuCl3-doped graphene on Ga-doped ZnO films that is used as transparent conducting electrodes for the LEDs, the average electroluminescence intensity is 1.2–1.7 times enhanced depending on the injection current. The chemical doping of graphene may produce the inhomogeneity in charge densities (i.e., electron/hole puddles) or roughness, which can play a role as grating couplers, resulting in such strong plasmon-enhanced light amplification. Based on theoretical calculations, the plasmon-coupled behavior is rigorously explained and a method of controlling its resonance condition is proposed.

  7. Titanium: light, strong, and white

    Science.gov (United States)

    Woodruff, Laurel; Bedinger, George

    2013-01-01

    Titanium (Ti) is a strong silver-gray metal that is highly resistant to corrosion and is chemically inert. It is as strong as steel but 45 percent lighter, and it is twice as strong as aluminum but only 60 percent heavier. Titanium dioxide (TiO2) has a very high refractive index, which means that it has high light-scattering ability. As a result, TiO2 imparts whiteness, opacity, and brightness to many products. ...Because of the unique physical properties of titanium metal and the whiteness provided by TiO2, titanium is now used widely in modern industrial societies.

  8. Strongly Interacting Light Dark Matter

    Directory of Open Access Journals (Sweden)

    Sebastian Bruggisser, Francesco Riva, Alfredo Urbano

    2017-09-01

    Full Text Available In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM can appear weakly coupled at small energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo Nambu-Goldstone Bosons and Goldstini are interesting targets for LHC missing-energy searches.

  9. Strongly interacting light dark matter

    International Nuclear Information System (INIS)

    Bruggisser, Sebastian; Riva, Francesco; Urbano, Alfredo

    2016-07-01

    In the presence of approximate global symmetries that forbid relevant interactions, strongly coupled light Dark Matter (DM) can appear weakly coupled at small-energy and generate a sizable relic abundance. Fundamental principles like unitarity restrict these symmetries to a small class, where the leading interactions are captured by effective operators up to dimension-8. Chiral symmetry, spontaneously broken global symmetries and non-linearly realized supersymmetry are examples of this. Their DM candidates (composite fermions, pseudo-Nambu-Goldstone Bosons and Goldstini) are interesting targets for LHC missing-energy searches.

  10. Manipulating light with strongly modulated photonic crystals

    International Nuclear Information System (INIS)

    Notomi, Masaya

    2010-01-01

    Recently, strongly modulated photonic crystals, fabricated by the state-of-the-art semiconductor nanofabrication process, have realized various novel optical properties. This paper describes the way in which they differ from other optical media, and clarifies what they can do. In particular, three important issues are considered: light confinement, frequency dispersion and spatial dispersion. First, I describe the latest status and impact of ultra-strong light confinement in a wavelength-cubic volume achieved in photonic crystals. Second, the extreme reduction in the speed of light is reported, which was achieved as a result of frequency dispersion management. Third, strange negative refraction in photonic crystals is introduced, which results from their unique spatial dispersion, and it is clarified how this leads to perfect imaging. The last two sections are devoted to applications of these novel properties. First, I report the fact that strong light confinement and huge light-matter interaction enhancement make strongly modulated photonic crystals promising for on-chip all-optical processing, and present several examples including all-optical switches/memories and optical logics. As a second application, it is shown that the strong light confinement and slow light in strongly modulated photonic crystals enable the adiabatic tuning of light, which leads to various novel ways of controlling light, such as adiabatic frequency conversion, efficient optomechanics systems, photon memories and photons pinning.

  11. White light emission from engineered silicon carbide

    DEFF Research Database (Denmark)

    Ou, Haiyan

    Silicon carbide (SiC) is a wide indirect bandgap semiconductor. The light emission efficiency is low in nature. But this material has very unique physical properties like good thermal conductivity, high break down field etc in addition to its abundance. Therefore it is interesting to engineer its...... light emission property so that to take fully potential applications of this material. In this talk, two methods, i.e. doping SiC heavily by donor-acceptor pairs and making SiC porous are introduced to make light emission from SiC. By co-doping SiC with nitrogen and boron heavily, strong yellow emission...

  12. Measurement of light emission in scintillation vials

    International Nuclear Information System (INIS)

    Duran Ramiro, M. Teresa; Garcia-Torano, Eduardo

    2005-01-01

    The efficiency and energy resolution of liquid scintillation counting (LSC) systems are strongly dependent on the optical characteristics of scintillators, vials, and reflectors. This article presents the results of measurements of the light-emission profile of scintillation vials. Two measurement techniques, autoradiographs and direct measurements with a photomultiplier tube, have been used to obtain light-emission distribution for standard vials of glass, etched glass and polyethylene. Results obtained with both techniques are in good agreement. For the first time, the effect of the meniscus in terms of light contribution has been numerically estimated. These results can help design LSC systems that are more efficient in terms of light collection

  13. Nitrous oxide emissions from light duty vehicles

    Science.gov (United States)

    Graham, Lisa A.; Belisle, Sheri L.; Rieger, Paul

    Nitrous oxide (N 2O) emissions measurements were made on light duty gasoline and light duty diesel vehicles during chassis dynamometer testing conducted at the Environment Canada and California Air Resources Board vehicle emissions laboratories between 2001 and 2007. Per phase and composite FTP emission rates were measured. A subset of vehicles was also tested using other driving cycles to characterize emissions as a function of different driving conditions. Vehicles were both new (automobile and light duty truck is not significant for any of the emission standards represented by the test fleet and the distinction between new and aged catalyst is significant for vehicles meeting all emission standards but Tier 2. This is likely due to the relatively low mileage accumulated by the Tier 2 vehicles in this study as compared to the durability requirement of the standard. The FTP composite N 2O emission factors for gasoline vehicles meeting emission standards more stringent than Tier 1 are substantially lower than those currently used by both Canada and the US for the 2005 inventories. N 2O emission factors from test cycles other than the FTP illustrate the variability of emission factors as a function of driving conditions. N 2O emission factors are shown to strongly correlate with NMHC/NMOG emission standards and less strongly with NO X and CO emission standards. A review of several published reports on the effect of gasoline sulfur content on N 2O emissions suggests that additional research is needed to adequately quantify the increase in N 2O emissions as a function of fuel sulfur.

  14. Bright visible light emission from graphene.

    Science.gov (United States)

    Kim, Young Duck; Kim, Hakseong; Cho, Yujin; Ryoo, Ji Hoon; Park, Cheol-Hwan; Kim, Pilkwang; Kim, Yong Seung; Lee, Sunwoo; Li, Yilei; Park, Seung-Nam; Yoo, Yong Shim; Yoon, Duhee; Dorgan, Vincent E; Pop, Eric; Heinz, Tony F; Hone, James; Chun, Seung-Hyun; Cheong, Hyeonsik; Lee, Sang Wook; Bae, Myung-Ho; Park, Yun Daniel

    2015-08-01

    Graphene and related two-dimensional materials are promising candidates for atomically thin, flexible and transparent optoelectronics. In particular, the strong light-matter interaction in graphene has allowed for the development of state-of-the-art photodetectors, optical modulators and plasmonic devices. In addition, electrically biased graphene on SiO2 substrates can be used as a low-efficiency emitter in the mid-infrared range. However, emission in the visible range has remained elusive. Here, we report the observation of bright visible light emission from electrically biased suspended graphene devices. In these devices, heat transport is greatly reduced. Hot electrons (∼2,800 K) therefore become spatially localized at the centre of the graphene layer, resulting in a 1,000-fold enhancement in thermal radiation efficiency. Moreover, strong optical interference between the suspended graphene and substrate can be used to tune the emission spectrum. We also demonstrate the scalability of this technique by realizing arrays of chemical-vapour-deposited graphene light emitters. These results pave the way towards the realization of commercially viable large-scale, atomically thin, flexible and transparent light emitters and displays with low operation voltage and graphene-based on-chip ultrafast optical communications.

  15. Coherent effects in semiconductor light emission

    Science.gov (United States)

    Kira, M.; Jahnke, Frank; Hoyer, W.; Koch, Stephan W.

    2000-03-01

    Coherent signatures in the semiconductor light emission are studied using a fully quantum mechanical theory for the system of photons and Coulomb interacting electron-hole pairs. The dominant light-matter correlations couple the semiconductor Bloch and luminescence equations yielding significant quantum corrections. A coherent excitation leads to squeezing of the emitted light as well as to entanglement between light and matter.

  16. Light dependency of VOC emissions from selected Mediterranean plant species

    Science.gov (United States)

    Owen, S. M.; Harley, P.; Guenther, A.; Hewitt, C. N.

    The light, temperature and stomatal conductance dependencies of volatile organic compound (VOC) emissions from ten plant species commonly found in the Mediterranean region were studied using a fully controlled leaf cuvette in the laboratory. At standard conditions of temperature and light (30°C and 1000 μmol m -2 s -1 PAR), low emitting species ( Arbutus unedo, Pinus halepensis, Cistus incanus, Cistus salvifolius, Rosmarinus officinalis and Thymus vulgaris) emitted between 0.1 and 5.0 μg (C) (total VOCs) g -1 dw h -1, a medium emitter ( Pinus pinea) emitted between 5 and 10 μg (C) g -1 dw h -1 and high emitters ( Cistus monspeliensis, Lavendula stoechas and Quercus sp.) emitted more than 10 μg (C) g -1 dw h -1. VOC emissions from all of the plant species investigated showed some degree of light dependency, which was distinguishable from temperature dependency. Emissions of all compounds from Quercus sp. were light dependent. Ocimene was one of several monoterpene compounds emitted by P. pinea and was strongly correlated to light. Only a fraction of monoterpene emissions from C. incanus exhibited apparent weak light dependency but emissions from this plant species were strongly correlated to temperature. Data presented here are consistent with past studies, which show that emissions are independent of stomatal conductance. These results may allow more accurate predictions of monoterpene emission fluxes from the Mediterranean region to be made.

  17. Strong light-matter interaction in graphene - Invited talk

    DEFF Research Database (Denmark)

    Xiao, Sanshui

    of graphene with noble-metal nanostructures is currently being explored for strong light-graphene interaction. We introduce a novel hybrid graphene-metal system for studying light-matter interactions with gold-void nanostructures exhibiting resonances in the visible range[1]. The hybrid system is further......Graphene has attracted lots of attention due to its remarkable electronic and optical properties, thus providing great promise in photonics and optoelectronics. However, the performance of these devices is generally limited by the weak light-matter interaction in graphene. The combination...

  18. White-Light Emission from Layered Halide Perovskites.

    Science.gov (United States)

    Smith, Matthew D; Karunadasa, Hemamala I

    2018-03-20

    exciton couples strongly to the lattice, creating transient elastic lattice distortions that can be viewed as "excited-state defects". These deformations stabilize the exciton affording a broad emission with a large Stokes shift. Although material defects very likely contribute to the emission width, our mechanistic studies suggest that the emission mostly arises from the bulk material. Ultrafast spectroscopic measurements support self-trapping, with new, transient, electronic states appearing upon photoexcitation. Importantly, the broad emission appears common to layered Pb-Br and Pb-Cl perovskites, albeit with a strong temperature dependence. Although the emission is attributed to light-induced defects, it still reflects changes in the crystal structure. We find that greater out-of-plane octahedral tilting increases the propensity for the broad emission, enabling synthetic control over the broad emission. Many of these perovskites have color rendering abilities that exceed commercial requirements and mixing halides affords both "warm" and "cold" white light. The most efficient white-light-emitting perovskite has a quantum efficiency of 9%. Improving this value will make these phosphors attractive for solid-state lighting, particularly as large-area coatings that can be deposited inexpensively. The emission mechanism can also be extended to other low-dimensional systems. We hope this Account aids in expanding the phase space of white-light emitters and controlling their exciton dynamics by the synthetic, spectroscopic, theoretical, and engineering communities.

  19. Strong coupling and stimulated emission in single parabolic quantum well microcavity for terahertz cascade

    International Nuclear Information System (INIS)

    Tzimis, A.; Savvidis, P. G.; Trifonov, A. V.; Ignatiev, I. V.; Christmann, G.; Tsintzos, S. I.; Hatzopoulos, Z.; Kavokin, A. V.

    2015-01-01

    We report observation of strong light-matter coupling in an AlGaAs microcavity (MC) with an embedded single parabolic quantum well. The parabolic potential is achieved by varying aluminum concentration along the growth direction providing equally spaced energy levels, as confirmed by Brewster angle reflectivity from a reference sample without MC. It acts as an active region of the structure which potentially allows cascaded emission of terahertz (THz) light. Spectrally and time resolved pump-probe spectroscopy reveals characteristic quantum beats whose frequencies range from 0.9 to 4.5 THz, corresponding to energy separation between relevant excitonic levels. The structure exhibits strong stimulated nonlinear emission with simultaneous transition to weak coupling regime. The present study highlights the potential of such devices for creating cascaded relaxation of bosons, which could be utilized for THz emission

  20. Various light particles emissions accompaning light heavy ion collisions

    International Nuclear Information System (INIS)

    Billerey, R.

    1981-01-01

    In this work we have investigated light particles emission accompanying heavy-ion induced reactions. The experiments were performed at the isochronous cyclotron of the I.S.N. de Grenoble and we got in and out of plane correlations between solid state and gazeous detectors. In 14 N (100 MeV) + 27 Al we have chosen, light particles emitted in coincidence with deep inelastic fragments or evaporation residues have been measured. Likewise we observed the correlations between fragments and fragments. The particularities we found between protons and alpha emissions are to be assigned to differences in separation energies, but their relative energies and angular momenta have also a significant part [fr

  1. Anomalous radon emission as precursor of medium to strong earthquakes

    Science.gov (United States)

    Zoran, Maria

    2016-03-01

    Anomalous radon (Rn222) emissions enhanced by forthcoming earthquakes is considered to be a precursory phenomenon related to an increased geotectonic activity in seismic areas. Rock microfracturing in the Earth's crust preceding a seismic rupture may cause local surface deformation fields, rock dislocations, charged particle generation and motion, electrical conductivity changes, radon and other gases emission, fluid diffusion, electrokinetic, piezomagnetic and piezoelectric effects as well as climate fluctuations. Space-time anomalies of radon gas emitted in underground water, soil and near the ground air weeks to days in the epicentral areas can be associated with the strain stress changes that occurred before the occurrence of medium and strong earthquakes. This paper aims to investigate temporal variations of radon concentration levels in air near or in the ground by the use of solid state nuclear track detectors (SSNTD) CR-39 and LR-115 in relation with some important seismic events recorded in Vrancea region, Romania.

  2. Light emission and finite-frequency shot noise in molecular junctions: from tunneling to contact

    DEFF Research Database (Denmark)

    Lu, Jing Tao; Christensen, Rasmus Bjerregaard; Brandbyge, Mads

    2013-01-01

    Scanning tunneling microscope induced light emission from an atomic or molecular junction has been probed from the tunneling to contact regime in recent experiments. There, the measured light emission yields suggest a strong correlation with the high-frequency current/charge fluctuations. We show...

  3. Light emission, light detection and strain sensing with nanocrystalline graphene

    International Nuclear Information System (INIS)

    Riaz, Adnan; Pyatkov, Feliks; Alam, Asiful; Dehm, Simone; Chakravadhanula, Venkata S K; Flavel, Benjamin S; Kübel, Christian; Krupke, Ralph; Felten, Alexandre; Lemmer, Uli

    2015-01-01

    Graphene is of increasing interest for optoelectronic applications exploiting light detection, light emission and light modulation. Intrinsically, the light–matter interaction in graphene is of a broadband type. However, by integrating graphene into optical micro-cavities narrow-band light emitters and detectors have also been demonstrated. These devices benefit from the transparency, conductivity and processability of the atomically thin material. To this end, we explore in this work the feasibility of replacing graphene with nanocrystalline graphene, a material which can be grown on dielectric surfaces without catalyst by graphitization of polymeric films. We have studied the formation of nanocrystalline graphene on various substrates and under different graphitization conditions. The samples were characterized by resistance, optical transmission, Raman and x-ray photoelectron spectroscopy, atomic force microscopy and electron microscopy measurements. The conducting and transparent wafer-scale material with nanometer grain size was also patterned and integrated into devices for studying light–matter interaction. The measurements show that nanocrystalline graphene can be exploited as an incandescent emitter and bolometric detector similar to crystalline graphene. Moreover the material exhibits piezoresistive behavior which makes nanocrystalline graphene interesting for transparent strain sensors. (paper)

  4. IRTS observation of zodiacal light and emission

    Science.gov (United States)

    Matsumoto, T.; Murakami, H.; Onaka, T.; Ootsubo, T.; Roellig, T. L.; Chan, K. -W.; Noda, M.

    1998-01-01

    We present the infrared spectrum of the zodiacal light and emission obtained by the Near-Infrared Spectrometer (NIRS) and Mid-Infrared Spectrometer (MIRS) onboard the Infrared Telescope in Space (IRTS). The wavelength coverages and spectral resolutions are 1.4-4.0 microns and 0.12 microns for the NIRS, and 4.5-11.7 microns and 0.23-0.36 microns for the MIRS respectively. Both instruments have the same beam size of 8 arcminutes square. The IRTS observations were made for 1995 March 29 - April 26. Here we present the data of two days, April 19 and April 20.

  5. Spontaneous light emission from fibers in MINOS

    International Nuclear Information System (INIS)

    Avvakumov, S.; Barrett, W.L.; Belias, T.; Bower, C.; Erwin, A.; Kordosky, M.; Lang, K.; Lee, R.; Liu, J.; Miller, W.; Mualem, L.; Nichol, R.; Nelson, J.; Pearce, G.; Proga, M.; Rebel, B.; Ruddick, K.; Smith, C.; Thomas, J.; Vahle, P.; Webb, R.

    2005-01-01

    We report on the observation and measurements of unexpected background rates in the MINOS Far Detector. The noise level at the Far Detector is significantly greater than that expected from natural radioactivity and intrinsic photomultiplier dark current. We have conducted a series of additional tests which demonstrate that the excess rate is caused by spontaneous light emission in the wavelength-shifting fibers, which are used to read out signals from scintillator strips. This noise due to fibers exhibits an exponential fall off with time with a decay time constant of the order of 100 days

  6. Directed emission of CdSe nanoplatelets originating from strongly anisotropic 2D electronic structure

    Science.gov (United States)

    Scott, Riccardo; Heckmann, Jan; Prudnikau, Anatol V.; Antanovich, Artsiom; Mikhailov, Aleksandr; Owschimikow, Nina; Artemyev, Mikhail; Climente, Juan I.; Woggon, Ulrike; Grosse, Nicolai B.; Achtstein, Alexander W.

    2017-12-01

    Intrinsically directional light emitters are potentially important for applications in photonics including lasing and energy-efficient display technology. Here, we propose a new route to overcome intrinsic efficiency limitations in light-emitting devices by studying a CdSe nanoplatelets monolayer that exhibits strongly anisotropic, directed photoluminescence. Analysis of the two-dimensional k-space distribution reveals the underlying internal transition dipole distribution. The observed directed emission is related to the anisotropy of the electronic Bloch states governing the exciton transition dipole moment and forming a bright plane. The strongly directed emission perpendicular to the platelet is further enhanced by the optical local density of states and local fields. In contrast to the emission directionality, the off-resonant absorption into the energetically higher 2D-continuum of states is isotropic. These contrasting optical properties make the oriented CdSe nanoplatelets, or superstructures of parallel-oriented platelets, an interesting and potentially useful class of semiconductor-based emitters.

  7. Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

    International Nuclear Information System (INIS)

    Nikolaev, Ivan S.; Lodahl, Peter; Vos, Willem L.

    2005-01-01

    We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges of enhanced emission. It appears that emission from embedded light sources is affected both by the periodicity and by the structural imperfections of the crystals: the photons are Bragg diffracted by lattice planes and scattered by unavoidable structural disorder. Using a model comprising diffuse light transport and photonic band structure, we quantitatively explain the directional emission spectra. This work provides detailed understanding of the transport of spontaneously emitted light in real photonic crystals, which is essential in the interpretation of quantum optics in photonic-band-gap crystals and for applications wherein directional emission and total emission power are controlled

  8. Strong water absorption in the dayside emission spectrum of the planet HD 189733b.

    Science.gov (United States)

    Grillmair, Carl J; Burrows, Adam; Charbonneau, David; Armus, Lee; Stauffer, John; Meadows, Victoria; van Cleve, Jeffrey; von Braun, Kaspar; Levine, Deborah

    2008-12-11

    Recent observations of the extrasolar planet HD 189733b did not reveal the presence of water in the emission spectrum of the planet. Yet models of such 'hot-Jupiter' planets predict an abundance of atmospheric water vapour. Validating and constraining these models is crucial to understanding the physics and chemistry of planetary atmospheres in extreme environments. Indications of the presence of water in the atmosphere of HD 189733b have recently been found in transmission spectra, where the planet's atmosphere selectively absorbs the light of the parent star, and in broadband photometry. Here we report the detection of strong water absorption in a high-signal-to-noise, mid-infrared emission spectrum of the planet itself. We find both a strong downturn in the flux ratio below 10 microm and discrete spectral features that are characteristic of strong absorption by water vapour. The differences between these and previous observations are significant and admit the possibility that predicted planetary-scale dynamical weather structures may alter the emission spectrum over time. Models that match the observed spectrum and the broadband photometry suggest that heat redistribution from the dayside to the nightside is weak. Reconciling this with the high nightside temperature will require a better understanding of atmospheric circulation or possible additional energy sources.

  9. Measurements of strong correlations in the transport of light through strongly scattering materials

    NARCIS (Netherlands)

    Akbulut, D.

    2013-01-01

    In this thesis, we study light transport through multiple scattering random photonic materials. Light incident on such materials undergoes many scattering events before exiting the material. The relation between the incident and the transmitted fields is determined by the optical transmission matrix

  10. White Light Emission from Vegetable Extracts

    Science.gov (United States)

    Singh, Vikram; Mishra, Ashok K.

    2015-06-01

    A mixture of extracts from two common vegetables, red pomegranate and turmeric, when photoexcited at 380 nm, produced almost pure white light emission (WLE) with Commission Internationale d’Eclairage (CIE) chromaticity index (0.35, 0.33) in acidic ethanol. It was also possible to obtain WLE in polyvinyl alcohol film (0.32, 0.25), and in gelatin gel (0.26, 0.33) using the same extract mixture. The colour temperature of the WLE was conveniently tunable by simply adjusting the concentrations of the component emitters. The primary emitting pigments responsible for contributing to WLE were polyphenols and anthocyanins from pomegranate, and curcumin from turmeric. It was observed that a cascade of Forster resonance energy transfer involving polyphenolics, curcumin and anthocyanins played a crucial role in obtaining a CIE index close to pure white light. The optimized methods of extraction of the two primary emitting pigments from their corresponding plant sources are simple, cheap and fairly green.

  11. Light and neutron scattering study of strongly interacting ionic micelles

    International Nuclear Information System (INIS)

    Degiorgio, V.; Corti, M.; Piazza, R.

    1989-01-01

    Dilute solutions of ionic micelles formed by biological glycolipids (gangliosides) have been investigated at various ionic strengths by static and dynamic light scaterring and by small-angle neutron scattering. The size and shape of the micelle is not appreciably affected by the added salt concentration in the range 0-100 mM NaCL. From the measured intensity of scattered light we derive the electric charge Z of the micelle by fitting the data to a theoretical calculation which uses a screened Coulomb potential for the intermicellar interaction, and the hypernetted chain approximation for the calculation of the radial distribution function. The correlation function derived from dynamic light scattering shows the long time contribution typical of concentrated polydisperse systems (author). 15 refs.; 6 figs

  12. Atomic and Free Electrons in a Strong Light Field

    International Nuclear Information System (INIS)

    Fedorov, Mikhail V.

    1998-02-01

    This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated Bremsstrahlung, free-electron lasers, ave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described oo, and their results are compared with those of the existing theoretical models. An extensive general theoretical introduction gives a good basis for subsequent parts of the book and is an independent and self-sufficient description of the most efficient theoretical methods of the strong-field and multiphoton physics. This book can serve as a textbook for graduate students

  13. Atomic and free electrons in a strong light field

    CERN Document Server

    Fedorov, Mikhail V

    1997-01-01

    This book presents and describes a series of unusual and striking strong-field phenomena concerning atoms and free electrons. Some of these phenomena are: multiphoton stimulated bremsstrahlung, free-electron lasers, wave-packet physics, above-threshold ionization, and strong-field stabilization in Rydberg atoms. The theoretical foundations and causes of the phenomena are described in detail, with all the approximations and derivations discussed. All the known and relevant experiments are described too, and their results are compared with those of the existing theoretical models.An extensive ge

  14. Strong-field-ionization suppression by light-field control

    DEFF Research Database (Denmark)

    Räsänen, Esa; Madsen, Lars Bojer

    2012-01-01

    in the intensity and thus preventing tunneling. In contrast, at high frequencies in the extreme ultraviolet regime the optimized pulses strongly couple with the (de)-excitations of the system, which leads to different pulse characteristics. Finally, we show that the applied target functional works, to some extent...

  15. Unidirectional light emission from low-index polymer microlasers

    International Nuclear Information System (INIS)

    Schermer, M.; Wiersig, J.; Bittner, S.; Singh, G.; Lebental, M.; Ulysse, C.

    2015-01-01

    We report on experiments with deformed polymer microlasers that have a low refractive index and exhibit unidirectional light emission. We demonstrate that the highly directional emission is due to transport of light rays along the unstable manifold of the chaotic saddle in phase space. Experiments, ray-tracing simulations, and mode calculations show very good agreement

  16. <strong>Potential for reduction of methane emissions from dairy cowsstrong>

    DEFF Research Database (Denmark)

    Johannes, Maike; Hellwing, Anne Louise Frydendahl; Lund, Peter

    2010-01-01

    Methane is a gas cows naturally produce in the rumen. However, it is also a potential greenhouse gas. Therefore, there is a certain interest from an environmental point of view to reduce methane emissions from dairy cows. Estimates from earlier studies indicate that there is a potential to reduce...... methane production by 10 to 25% by changing the feeding strategies. Several feedstuffs influence methane production, such as additional fat. The increase of the concentrate proportion can potentially decrease methane by decreasing the rumen degradability of the diet or by changing the rumen fermentation...

  17. Route to strong localization of light: The role of disorder

    KAUST Repository

    Molinari, Diego P.

    2012-01-01

    By employing Random Matrix Theory (RMT) and firstprinciple calculations, we investigated the behavior of Anderson localization in 1D, 2D and 3D systems characterized by a varying disorder. In particular, we considered random binary layer sequences in 1D and structurally disordered photonic crystals in two and three dimensions. We demonstrated the existence of a unique optimal degree of disorder that yields the strongest localization possible. In this regime, localized modes are constituted by defect states, which can show subwavelength confinement properties. These results suggest that disorder offers a new avenue for subwavelength light localization in purely dielectric media. © 2012 Optical Society of America.

  18. Electromagnetic emission of a strongly charged oscillating droplet

    Science.gov (United States)

    Grigor'ev, A. I.; Kolbneva, N. Yu.; Shiryaeva, S. O.

    2016-08-01

    Analytical expressions for electric field in the vicinity of an oscillating strongly charged droplet of nonviscous conducting liquid and intensity of electromagnetic radiation are derived in the linear approximation with respect to perturbation amplitude of the droplet surface. Order-of-magnitude estimations of the radiation intensity are presented. The intensity of electromagnetic radiation of a ball lightning that can be simulated using a charged droplet is not related to the surface oscillations.

  19. A Sample of Quasars with Strong Nitrogen Emission Lines from the Sloan Digital Sky Survey

    DEFF Research Database (Denmark)

    Jiang, Linhua; Fan, Xiaohui; Vestergaard, Marianne

    2008-01-01

    We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \\AA) at 1.7......We report on 293 quasars with strong NIV] lambda 1486 or NIII] lambda 1750 emission lines (rest-frame equivalent width > 3 \\AA) at 1.7...

  20. Light-induced protein nitration and degradation with HONO emission

    Science.gov (United States)

    Meusel, Hannah; Elshorbany, Yasin; Kuhn, Uwe; Bartels-Rausch, Thorsten; Reinmuth-Selzle, Kathrin; Kampf, Christopher J.; Li, Guo; Wang, Xiaoxiang; Lelieveld, Jos; Pöschl, Ulrich; Hoffmann, Thorsten; Su, Hang; Ammann, Markus; Cheng, Yafang

    2017-10-01

    Proteins can be nitrated by air pollutants (NO2), enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO) from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM). Bovine serum albumin (BSA) and ovalbumin (OVA) were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS/UV illuminated conditions, while simultaneous decomposition of (nitrated) proteins was also found during long-term (20 h) irradiation exposure. Measurements of gas exchange on TNM-nitrated proteins revealed that HONO can be formed and released even without contribution of instantaneous heterogeneous NO2 conversion. NO2 exposure was found to increase HONO emissions substantially. In particular, a strong dependence of HONO emissions on light intensity, relative humidity, NO2 concentrations and the applied coating thickness was found. The 20 h long-term studies revealed sustained HONO formation, even when concentrations of the intact (nitrated) proteins were too low to be detected after the gas exchange measurements. A reaction mechanism for the NO2 conversion based on the Langmuir-Hinshelwood kinetics is proposed.

  1. Electronic emission produced by light projectiles at intermediate energies

    International Nuclear Information System (INIS)

    Bernardi, G.C.

    1989-01-01

    Two aspects of the electronic emission produced by light projectiles of intermediate energies have been studied experimentally. In the first place, measurements of angular distributions in the range from θ = 0 deg -50 deg induced by collisions of 50-200 keV H + incident on He have been realized. It was found that the double differential cross section of electron emission presents a structure focussed in the forward direction and which extends up to relatively large angles. Secondly, the dependence of the double differential cross section on the projectile charge was studied using H + and He 3 2+ projectiles of 50 and 100 keV/amu incident on He. Strong deviations from a constant scaling factor were found for increasing projectile charge. The double differential cross sections and the single differential cross sections as a function of the emission angle, and the ratios of the emissions induced by He 3 2+ and H + at equal incident projectile velocities are compared with the 'Continuum Distorted Wave-Eikonal Initial State' (CDW-EIS) approximation and the 'Classical Trajectory Monte Carlo' (CTMC) method. Both approximations, in which the potential of the projectile exercises a relevant role, reproduce the general aspects of the experimental results. An electron analyzer and the corresponding projectile beam line has been designed and installed; it is characterized by a series of properties which are particularly appropriate for the study of double differential electronic emission in gaseous as well as solid targets. The design permits to assure the conditions to obtain a well localized gaseous target and avoid instrumental distortions of the measured distributions. (Author) [es

  2. STRONG POLYCYCLIC AROMATIC HYDROCARBON EMISSION FROM z ∼ 2 ULIRGs

    International Nuclear Information System (INIS)

    Desai, Vandana; Soifer, B. T.; Melbourne, Jason; Dey, Arjun; Brand, Kate; Brodwin, Mark; Jannuzi, Buell T.; Le Floc'h, Emeric; Armus, Lee; Teplitz, Harry; Brown, Michael J. I.; Houck, James R.; Weedman, Daniel W.; Ashby, Matthew L. N.; Huang Jiasheng; Smith, Howard A.; Willner, Steve P.; Gonzalez, Anthony

    2009-01-01

    Using the Infrared Spectrograph on board the Spitzer Space Telescope, we present low-resolution (64 ν (24 μm)>0.5 mJy; (2) R - [24]>14 Vega mag; and (3) a prominent rest frame 1.6 μm stellar photospheric feature redshifted into Spitzer's 3-8 μm IRAC bands. Of these, 20 show emission from polycyclic aromatic hydrocarbons (PAHs), usually interpreted as signatures of star formation. The PAH features indicate redshifts in the range 1.5 < z < 3.0, with a mean of (z) = 1.96 and a dispersion of 0.30. Based on local templates, these sources have extremely large infrared luminosities, comparable to that of submillimeter galaxies. Our results confirm previous indications that the rest-frame 1.6 μm stellar bump can be efficiently used to select highly obscured star-forming galaxies at z ∼ 2, and that the fraction of starburst-dominated ULIRGs increases to faint 24 μm flux densities. Using local templates, we find that the observed narrow redshift distribution is due to the fact that the 24 μm detectability of PAH-rich sources peaks sharply at z = 1.9. We can analogously use observed spectral energy distributions to explain the broader redshift distribution of Spitzer-detected ULIRGs that are dominated by an active galactic nucleus (AGN). Finally, we conclude that z ∼ 2 sources with a detectable 1.6 μm stellar opacity feature lack sufficient AGN emission to veil the 7.7 μm PAH band.

  3. Spontaneous electromagnetic emission from a strongly localized plasma flow.

    Science.gov (United States)

    Tejero, E M; Amatucci, W E; Ganguli, G; Cothran, C D; Crabtree, C; Thomas, E

    2011-05-06

    Laboratory observations of electromagnetic ion-cyclotron waves generated by a localized transverse dc electric field are reported. Experiments indicate that these waves result from a strong E×B flow inhomogeneity in a mildly collisional plasma with subcritical magnetic field-aligned current. The wave amplitude scales with the magnitude of the applied radial dc electric field. The electromagnetic signatures become stronger with increasing plasma β, and the radial extent of the power is larger than that of the electrostatic counterpart. Near-Earth space weather implications of the results are discussed.

  4. Strong-field physics with singular light beams

    Science.gov (United States)

    Zürch, M.; Kern, C.; Hansinger, P.; Dreischuh, A.; Spielmann, Ch.

    2012-10-01

    Light beams carrying a point singularity with a screw-type phase distribution are associated with an optical vortex. The corresponding momentum flow leads to an orbital angular momentum of the photons. The study of optical vortices has led to applications such as particle micro-manipulation, imaging, interferometry, quantum information and high-resolution microscopy and lithography. Recent analyses showed that transitions forbidden by selection rules seem to be allowed when using optical vortex beams. To exploit these intriguing new applications, it is often necessary to shorten the wavelength by nonlinear frequency conversion. However, during the conversion the optical vortices tend to break up. Here we show that optical vortices can be generated in the extreme ultraviolet (XUV) region using high-harmonic generation. The singularity impressed on the fundamental beam survives the highly nonlinear process. Vortices in the XUV region have the same phase distribution as the driving field, which is in contradiction to previous findings, where multiplication of the momentum by the harmonic order is expected. This approach opens the way for several applications based on vortex beams in the XUV region.

  5. Scanning tunnelling microscope light emission: Finite temperature current noise and over cut-off emission.

    Science.gov (United States)

    Kalathingal, Vijith; Dawson, Paul; Mitra, J

    2017-06-14

    The spectral distribution of light emitted from a scanning tunnelling microscope junction not only bears its intrinsic plasmonic signature but is also imprinted with the characteristics of optical frequency fluc- tuations of the tunnel current. Experimental spectra from gold-gold tunnel junctions are presented that show a strong bias (V b ) dependence, curiously with emission at energies higher than the quantum cut-off (eV b ); a component that decays monotonically with increasing bias. The spectral evolution is explained by developing a theoretical model for the power spectral density of tunnel current fluctuations, incorporating finite temperature contribution through consideration of the quantum transport in the system. Notably, the observed decay of the over cut-off emission is found to be critically associated with, and well explained in terms of the variation in junction conductance with V b . The investigation highlights the scope of plasmon-mediated light emission as a unique probe of high frequency fluctuations in electronic systems that are fundamental to the electrical generation and control of plasmons.

  6. Strong Correlation Between Isoprene Emission and Gross Photosynthetic Capacity During Leaf Phenology of the Tropical Tree Species Hymenaea courbaril

    Science.gov (United States)

    Kuhn, U.; Rottenberger, S.; Biesenthal, T.; Wolf, A.; Schebeske, G.; Ciccioli, P.; Kesselmeier, J.

    2004-12-01

    Composition and amount of volatile organic compound (VOC) emission of the tropical tree species Hymenaea courbaril was studied under different developmental stages at a remote Amazonian rainforest site. The different stages covered young leaves (= grown full in size, but not fully turgescent) in the end of the dry season, mature leaves in the end of dry and wet season, and senescent leaves in the end of dry season. Though the diel isoprene emissions pattern could adequately be modelled by a current isoprene algorithm, the basal emission capacity of isoprene changed considerably over the course of leaf development. The inadequacy of using one single standard emission factor to represent the VOC emission capacity of tropical vegetation for an entire seasonal cycle is obvious. A strong linear correlation between the isoprene emission capacity and the gross photosynthetic capacity (GPmax) covering all developmental stages and seasons was observed. Hence, basic leaf photosynthetic activity may offer a valuable basis to model the seasonal variation of isoprene emission, especially in tropical regions where the environmental conditions vary less than in temperate regions. Of special interest was the light dependent monoterpene emission found exclusively in the period between bud break and leave maturity. The finding of this temporary emergence of monoterpene emission may be of general interest in understanding both the ecological functions of isoprenoid production and the regulatory processes involved.

  7. Visible light emission from porous silicon carbide

    DEFF Research Database (Denmark)

    Ou, Haiyan; Lu, Weifang

    2017-01-01

    Light-emitting silicon carbide is emerging as an environment-friendly wavelength converter in the application of light-emitting diode based white light source for two main reasons. Firstly, SiC has very good thermal conductivity and therefore a good substrate for GaN growth in addition to the sma...... by time-resolved photoluminescence. The ultrashort lifetime in the order of ~70ps indicates porous SiC is very promising for the application in the ultrafast visible light communications.......Light-emitting silicon carbide is emerging as an environment-friendly wavelength converter in the application of light-emitting diode based white light source for two main reasons. Firstly, SiC has very good thermal conductivity and therefore a good substrate for GaN growth in addition to the small...

  8. CO2 emissions from Super-light Structures

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Bagger, Anne

    2011-01-01

    CO2 emission from the construction of buildings is seldom taken into account because focus is primarily on building operation. New technologies have therefore mainly been developed to reduce the energy consumption connected to operation. Super-light technology is a new structural principle giving...... rise to a substantial reduction of the CO2 emission in the construction phase. The present paper describes how the CO2 emission is reduced when using Super-light technology instead of traditional structural components. Estimations of the CO2 emissions from a number of projects using various...

  9. Using Strong Solar Coronal Emission Lines as Coronal Flux Proxies

    Science.gov (United States)

    Falconer, David A.; Jordan, Studart D.; Davila, Joseph M.; Thomas, Roger J.; Andretta, Vincenzo; Brosius, Jeffrey W.; Hara, Hirosha

    1997-01-01

    A comparison of Skylab results with observations of the strong EUV lines of Fe XVI at 335 A and 361 A from the Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) flight of 1989 suggests that these lines, and perhaps others observed with SERTS, might offer good proxies for estimating the total coronal flux over important wavelength ranges. In this paper, we compare SERTS observations from a later, 1993 flight with simultaneous cospatial Yohkoh soft X-ray observations to test this suggestion over the energy range of the Soft X-ray Telescope (SXT) on Yohkoh. Both polynomial and power-law fits are obtained, and errors are estimated, for the SERTS lines of Fe XVI 335 A and 361 A, Fe XV 284 A and 417 A, and Mg IX 368 A. It is found that the power-law fits best cover the full range of solar conditions from quiet Sun through active region, though not surprisingly the 'cooler' Mg IX 368 A line proves to be a poor proxy. The quadratic polynomial fits yield fair agreement over a large range for all but the Mg IX line, but the linear fits fail conspicuously when extrapolated into the quiet Sun regime. The implications of this work for the He 11 304 A line formation problem are briefly considered. The paper concludes with a discussion of the value of these iron lines observed with SERTS for estimating stellar coronal fluxes, as observed for example with the EUVE satellite.

  10. Light emitting device having peripheral emissive region

    Science.gov (United States)

    Forrest, Stephen R

    2013-05-28

    Light emitting devices are provided that include one or more OLEDs disposed only on a peripheral region of the substrate. An OLED may be disposed only on a peripheral region of a substantially transparent substrate and configured to emit light into the substrate. Another surface of the substrate may be roughened or include other features to outcouple light from the substrate. The edges of the substrate may be beveled and/or reflective. The area of the OLED(s) may be relatively small compared to the substrate surface area through which light is emitted from the device. One or more OLEDs also or alternatively may be disposed on an edge of the substrate about perpendicular to the surface of the substrate through which light is emitted, such that they emit light into the substrate. A mode expanding region may be included between each such OLED and the substrate.

  11. Analytical modeling of light transport in scattering materials with strong absorption

    NARCIS (Netherlands)

    Meretska, M. L.; Uppu, R.; Vissenberg, Gilles; Lagendijk, A.; Ijzerman, W. L.; Vos, W. L.

    2017-01-01

    We have investigated the transport of light through slabs that both scatter and strongly absorb, a situation that occurs in diverse application fields ranging from biomedical optics, powder technology, to solid-state lighting. In particular, we study the transport of light in the visible wavelength

  12. Trap-state-assisted white light emission from a CdSe nanocrystal integrated hybrid light-emitting diode.

    Science.gov (United States)

    Chandramohan, S; Ryu, Beo Deul; Kim, Hyun Kyu; Hong, Chang-Hee; Suh, Eun-Kyung

    2011-03-15

    This Letter reports on the fabrication of hybrid white-light-emitting diodes made of semiconductor nanocrystals (NCs) integrated on InGaN/GaN LEDs. Using core type and core/shell type CdSe NCs, the white light properties are systematically engineered for white light generation with high color rendering index (CRI). Unlike CdSe/ZnS core/shell NCs, which exhibited a unique narrowband edge emission, core type CdSe NCs offered extended broad emission toward orange/red wavelengths associated with deep trap states. Consequently, the light-emitting properties of the devices showed strong dependence on the type of NCs used, and devices with CdSe NCs offered admirable characteristics, such as Commission Internationale d'Eclairage coordinates of (0.356, 0.330) and a CRI as high as 87.4.

  13. Light Emission and Energy Transfer in Nanoscale Semiconductor Photonic Devices

    National Research Council Canada - National Science Library

    Kolbas, Robert

    1997-01-01

    The overall objective of this experimental program is to control the light emission properties and energy transfer mechanisms in nanoscale semiconductor structures in order to realize new or improved photonic devices...

  14. Emission behavior of dual-side emissive transparent white organic light-emitting diodes.

    Science.gov (United States)

    Choi, Wing Hong; Tam, Hoi Lam; Ma, Dongge; Zhu, Furong

    2015-06-01

    White organic light-emitting diodes (WOLEDs) resemble light more naturally, with emission spectrum that is comfortable to the human eye. The transparent WOLEDs can be almost invisible by day and can emit a pleasant diffused light at night, allowing the surface light source to shine in both directions, an exciting new lighting technology that could bring new device concepts. However, undesirable angular-dependent emission in transparent WOLEDs is often observed, due to the microcavity effect. In this work, the emission behavior of dual-side emissive transparent WOLEDs was studied experimentally and theoretically. It is found that avoidance of the overlap between the peak wavelengths of the emitters and the resonant wavelength of the organic microcavity moderates the angular-dependent electroluminescence emission behavior, thereby improving the color stability of the transparent white WOLEDs over a broad range of the viewing angle.

  15. Strong blue excitonic emission from CdS nanocrystallites prepared by LB technique

    International Nuclear Information System (INIS)

    Mandal, P.; Talwar, S.S.; Major, S.S.; Srinivasa, R.S.

    2009-01-01

    CdS nanocrystallites formed in ordered fatty acid LB multilayers exhibited strong surface states emission ∝550 nm and weak excitonic emission ∝400 nm. Treatment with aqueous CdCl 2 resulted in the suppression of surface states emission and enhancement of the blue excitonic emission. Subsequent annealing in air at 200 C caused an order of magnitude enhancement of excitonic emission. The growth of nanocrystallites during annealing as seen from the red-shift of excitonic absorption and emission is suppressed by the CdCl 2 treatment. The hindered growth of nanocrystallites, the significant enhancement of excitonic emission from CdS, and the suppression of surface states emission are attributed to surface passivation of CdS nanocrystallites by surface oxide formation. (orig.)

  16. AMMONIA EMISSIONS FROM THE EPA'S LIGHT DUTY TEST VEHICLE

    Science.gov (United States)

    The paper discusses measurements of ammonia (NH3) emissions from EPA's light duty test vehicle while operated on a dynamometer. The vehicle's (1993 Chevrolet equipped with a three-way catalyst) emissions were measured for three transient (urban driving, highway fuel economy, and ...

  17. Electric current induced light emission from C-60

    NARCIS (Netherlands)

    Palstra, TTM; Haddon, RC; Lyons, KB; Kafafi, ZH

    1997-01-01

    We report the luminescence of C-60 crystals and films due to the passage of an electrical current. The current-voltage behaviour is highly non-linear with light-emission beyond a threshold voltage. The emission spectrum is featureless and resembles black body radiation with an effective temperature

  18. Electric Current Induced Light Emission from C60

    NARCIS (Netherlands)

    Palstra, T.T.M.; Haddon, R.C.; Lyons, K.B.

    1997-01-01

    We report the luminescence of C60 crystals and films due to the passage of an electrical current. The current-voltage behavior is highly non-linear with light-emission beyond a threshold voltage. The emission spectrum is featureless and resembles black-body radiation with an effective temperature on

  19. Blue and white light emission from zinc oxide nanoforests

    Directory of Open Access Journals (Sweden)

    Nafisa Noor

    2015-12-01

    Full Text Available Blue and white light emission is observed when high voltage stress is applied using micrometer-separated tungsten probes across a nanoforest formed of ZnO nanorods. The optical spectrum of the emitted light consistently shows three fine peaks with very high amplitude in the 465–485 nm (blue range, corresponding to atomic transitions of zinc. Additional peaks with smaller amplitudes in the 330–650 nm range and broad spectrum white light is observed depending on the excitation conditions. The spatial and spectral distribution of the emitted light, with pink–orange regions identifying percolation paths in some cases and high intensity blue and white light with center to edge variations in others, indicate that multiple mechanisms lead to light emission. Under certain conditions, the tungsten probe tips used to make electrical contact with the ZnO structures melt during the excitation, indicating that the local temperature can exceed 3422 °C, which is the melting temperature of tungsten. The distinct and narrow peaks in the optical spectra and the abrupt increase in current at high electric fields suggest that a plasma is formed by application of the electrical bias, giving rise to light emission via atomic transitions in gaseous zinc and oxygen. The broad spectrum, white light emission is possibly due to the free electron transitions in the plasma and blackbody radiation from molten silicon. The white light may also arise from the recombination through multiple defect levels in ZnO or due to the optical excitation from solid ZnO. The electrical measurements performed at different ambient pressures result in light emission with distinguishable differences in the emission properties and I–V curves, which also indicate that the dielectric breakdown of ZnO, sublimation, and plasma formation processes are the underlying mechanisms.

  20. GaN/ZnO nanorod light emitting diodes with different emission spectra.

    Science.gov (United States)

    Ng, A M C; Xi, Y Y; Hsu, Y F; Djurisić, A B; Chan, W K; Gwo, S; Tam, H L; Cheah, K W; Fong, P W K; Lui, H F; Surya, C

    2009-11-04

    Light emitting diodes (LEDs) consisting of p-GaN epitaxial films and n-ZnO nanorods have been fabricated and characterized. The rectifying behavior and emission spectra were strongly dependent on the electronic properties of both GaN film and ZnO nanorods. Light emission under both forward and reverse bias was obtained in all cases, and emission spectra could be changed by annealing the ZnO nanorods. The emission spectra could be further tuned by using a GaN LED epiwafer as a substrate. Both forward and backward diode behavior has been observed and the emission spectra were significantly affected by both the properties of the GaN substrate and the annealing conditions for the ZnO nanorods.

  1. Light emission probing quantum shot noise and charge fluctuations at a biased molecular junction

    DEFF Research Database (Denmark)

    Schneider, N.L.; Lu, Jing Tao; Brandbyge, M.

    2012-01-01

    The emission of plasmonic light from a single C60 molecule on Cu(111) is probed in a scanning tunneling microscope from the weak-coupling, tunneling range to strong coupling of the molecule to the electrodes at contact. At positive sample voltage the photon yield decreases owing to shot...

  2. Emissions from light and medium goods vehicles in Denmark

    DEFF Research Database (Denmark)

    Jørgensen, Kaj

    1996-01-01

    The article analyses atmospheric pollution of light goods vehicles (i.e. freight vehicles lighter than 6 tonnes) and medium goods vehicles (i.e. 6-24 t delivery trucks) in Denmark, and evaluated the scope for emission reductions. Light goods vehicles are very inefficient vehicles, and moreover have...... inappropriate utilisation patterns, while medium goods vehicles, in comparison, are more efficient with regard to both construction and utilisation. An emission inventory of these vehicles is produced, covering fuel consumption and a range of emissions, and including heavy goods vehicles (i.e. vehicles over 24...

  3. Beta delayed particle emission in light nuclei

    International Nuclear Information System (INIS)

    Riisager, K.; Gabelmann, H.

    1991-01-01

    A short discussion of theoretical treatments of beta delayed particle emission is followed by a presentation of data on the newly found beta delayed deuteron decay of 6 He. This decay cannot be described properly with existing theories. (author) 8 refs.; 3 figs

  4. Unregulated emissions from light-duty hybrid electric vehicles

    Science.gov (United States)

    Suarez-Bertoa, R.; Astorga, C.

    2016-07-01

    The number of registrations of light duty hybrid electric vehicles has systematically increased over the last years and it is expected to keep growing. Hence, evaluation of their emissions becomes very important in order to be able to anticipate their impact and share in the total emissions from the transport sector. For that reason the emissions from a Euro 5 compliant hybrid electric vehicle (HV2) and a Euro 5 plug-in hybrid electric vehicle (PHV1) were investigated with special interest on exhaust emissions of ammonia, acetaldehyde and ethanol. Vehicles were tested over the World harmonized Light-duty Test Cycle (WLTC) at 23 and -7 °C using two different commercial fuels E5 and E10 (gasoline containing 5% and 10% vol/vol of ethanol, respectively). PHV1 resulted in lower emissions than HV2 due to the pure electric strategy used by the former. PHV1 and HV2 showed lower regulated emissions than conventional Euro 5 gasoline light duty vehicles. However, emissions of ammonia (2-8 and 6-15 mg km-1 at 22 and -7 °C, respectively), ethanol (0.3-0.8 and 2.6-7.2 mg km-1 at 22 and -7 °C, respectively) and acetaldehyde (∼0.2 and 0.8-2.7 mg km-1 at 22 and -7 °C, respectively) were in the same range of those recently reported for conventional gasoline light duty vehicles.

  5. Controlling spontaneous emission of light by photonic crystals

    DEFF Research Database (Denmark)

    Lodahl, Peter

    2005-01-01

    Photonic bandgap crystals were proposed almost two decades ago as a unique tool for controlling propagation and emission of light. Since then the research field of photonic crystals has exploded and many beautiful demonstrations of the use of photonic crystals and fibers for molding light...... propagation have appeared that hold great promises for integrated optics. These major achievements solidly demonstrate the ability to control propagation of light. In contrast, an experimental demonstration of the use of photonic crystals for timing the emission of light has so far lacked. In a recent...... publication in Nature, we have demonstrated experimentally that both the direction and time of spontaneous emission can be controlled, thereby confirming the original proposal by Eli Yablonovich that founded the field of photonic crystals. We believe that this work opens new opportunities for solid...

  6. Entangled Light Emission From a Diode

    International Nuclear Information System (INIS)

    Stevenson, R. M.; Shields, A. J.; Salter, C. L.; Farrer, I.; Nicoll, C. A.; Ritchie, D. A.

    2011-01-01

    Electrically-driven entangled photon generation is demonstrated for the first time using a single semiconductor quantum dot embedded in a light emitting diode structure. The entanglement fidelity is shown to be of sufficient quality for applications such as quantum key distribution.

  7. Strong Transverse Photosphere Magnetic Fields and Twist in Light Bridge Dividing Delta Sunspot of Active Region 12673

    Science.gov (United States)

    Wang, Haimin; Yurchyshyn, Vasyl; Liu, Chang; Ahn, Kwangsu; Toriumi, Shin; Cao, Wenda

    2018-01-01

    Solar Active Region (AR) 12673 is the most flare productive AR in the solar cycle 24. It produced four X-class flares including the X9.3 flare on 06 September 2017 and the X8.2 limb event on 10 September. Sun and Norton (2017) reported that this region had an unusual high rate of flux emergence, while Huang et al. (2018) reported that the X9.3 flare had extremely strong white-light flare emissions. Yang at al. (2017) described the detailed morphological evolution of this AR. In this report, we focus on usual behaviors of the light bridge (LB) dividing the delta configuration of this AR, namely the strong magnetic fields (above 5500 G) in the LB and apparent photospheric twist as shown in observations with a 0.1 arcsec spatial resolution obtained by the 1.6m telescope at Big Bear Solar Observatory.

  8. The CO/NOx emissions of swirled, strongly pulsed jet diffusion flames

    KAUST Repository

    Liao, Ying-Hao

    2014-05-28

    The CO and NOx exhaust emissions of swirled, strongly pulsed, turbulent jet diffusion flames were studied experimentally in a coflow swirl combustor. Measurements of emissions were performed on the combustor centerline using standard emission analyzers combined with an aspirated sampling probe located downstream of the visible flame tip. The highest levels of CO emissions are generally found for compact, isolated flame puffs, which is consistent with the quenching due to rapid dilution with excess air. The imposition of swirl generally results in a decrease in CO levels by up to a factor of 2.5, suggesting more rapid and compete fuel/air mixing by imposing swirl in the coflow stream. The levels of NO emissions for most cases are generally below the steady-flame value. The NO levels become comparable to the steady-flame value for sufficiently short jet-off times. The swirled coflow air can, in some cases, increase the NO emissions due to a longer combustion residence time due to the flow recirculation within the swirl-induced recirculation zone. Scaling relations, when taking into account the impact of air dilution over an injection cycle on the flame length, reveal a strong correlation between the CO emissions and the global residence time. However, the NO emissions do not successfully correlate with the global residence time. For some specific cases, a compact flame with a simultaneous decrease in both CO and NO emissions compared to the steady flames was observed. © Copyright © Taylor & Francis Group, LLC.

  9. Wavelength dependence of light diffusion in strongly scattering macroporous gallium phosphide

    NARCIS (Netherlands)

    Peeters, W.H.; Vellekoop, Ivo Micha; Mosk, Allard; Lagendijk, Aart

    2008-01-01

    We present time-resolved measurements of light transport through strongly scattering macroporous gallium phosphide at various vacuum wavelengths between 705 nm and 855 nm. Within this range the transport mean free path is strongly wavelength dependent, whereas the observed energy velocity is shown

  10. Light bending by nonlinear electrodynamics under strong electric and magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jin Young; Lee, Taekoon, E-mail: jykim@kunsan.ac.kr, E-mail: tlee@kunsan.ac.kr [Department of Physics, Kunsan National University, Daihakro 558, Kunsan 573-701 (Korea, Republic of)

    2011-11-01

    We calculate the bending angles of light under the strong electric and magnetic fields by a charged black hole and a magnetized neutron star according to the nonlinear electrodynamics of Euler-Heisenberg interaction. The bending angle of light by the electric field of charged black hole is computed from geometric optics and a general formula is derived for light bending valid for any orientation of the magnetic dipole. The astronomical significance of the light bending by magnetic field of a neutron star is discussed.

  11. Light emission and luminescence enhancement in Erbium Oxide nanoparticles

    Science.gov (United States)

    Wilkinson, Lynda; Maqbool, Muhammad; Ahmad, Iftikhar

    2011-10-01

    We reports light emission from Erbium Oxide nanoparticles. The nanoparticles, with 45 nm diameter, were obtained in the form of nanopowder. These nanoparticles were characterized for light emission under a 30 mW, 532 nm Nd:YAG laser excitation and a Photoluminescence (PL) system, made by Princeton Instrumentation, with a Pixis brand CCD camera. The nanoparticles were stick on a scotch tape and placed in the PL system. Spectrum of the light emitted from the nanoparticles was obtained and analyzed after subtracting the background spectrum. Two emission peaks were observed around 554 nm and 820 nm. The green emission at 554 nm was obtained as a result of ^2H11/2 ->^4I15/2 transition, and the near infrared emission from ^4I9/2->^4I15/2 transition. The process was also repeated in vacuum and it was found that the green emission enhances tremendously, showing the importance of Erbium Oxide nanoparticles optical and biophotonics applications.

  12. Strongly emissive plasma-facing material under space-charge limited regime: Application to emissive probes

    Czech Academy of Sciences Publication Activity Database

    Cavalier, Jordan; Lemoine, N.; Bousselin, G.; Plihon, N.; Ledig, J.

    2017-01-01

    Roč. 24, č. 1 (2017), č. článku 013506. ISSN 1070-664X Institutional support: RVO:61389021 Keywords : plasma * tokamak * emissive probes Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.115, year: 2016 http://dx. doi . org /10.1063/1.4973557

  13. AC-driven organic light emission devices with carbon nanotubes

    Science.gov (United States)

    Jeon, So-Yeon; Yu, SeGi

    2017-02-01

    We have investigated alternating current (AC)-driven organic light-emitting devices (OLEDs), with carbon nanotubes (CNTs) incorporated within the emission layer. With CNT incorporation, the brightness of the OLEDs was substantially improved, and the turn-on voltage was reduced by at least a factor of five. Furthermore, the current levels of the CNT-incorporated OLEDs were lower than that of the reference device. A roughly 70% decrease in the current level was obtained for a CNT concentration of 0.03 wt%. This was accomplished by keeping the concentration of CNTs low and the length of CNTs short, which helped to suppress the percolation networking of CNTs within the emitting layer. Strong local electric fields near the end-tips of CNTs and micro-capacitors formed by dispersed CNTs might have caused this high brightness and these low currents. CNT incorporation in the emitting layer can improve the characteristics of AC-driven OLEDs, which are considered to be one of the candidates for flat panel displays and lightning devices.

  14. Potency of energy saving and emission reduction from lighting system in residential sector of Indonesia

    Science.gov (United States)

    Ambarita, H.

    2018-03-01

    The Government of Indonesia (GoI) has a strong commitment to the target of decreasing energy intensity and reducing Greenhouse gas emissions. One of the significant solutions to reach the target is increasing energy efficiency in the lighting system in the residential sector. The objective of this paper is twofold, to estimate the potency of energy saving and emission reduction from lighting in the residential sector. Literature related to the lighting system in Indonesia has been reviewed to provide sufficient data for the estimation of the energy saving and emission reduction. The results show that the in the year 2016, a total of 95.33 TWh of nationally produced electricity is used in the residential sector. This is equal to 44% of total produced electricity. The number of costumers is 64.78 million houses. The average number of lamps and average wattage of lamps used in Indonesia are 8.35 points and 13.8 W, respectively. The number of lighting and percentage of electricity used for lighting in the residential sector in Indonesia are 20.03 TWh (21.02 %) and 497 million lamps, respectively. The projection shows that in the year 2026 the total energy for lighting and number of lamps in the residential sector are 25.05 TWh and 619 million, respectively. By promoting the present technology of high efficient lamps (LED), the potency of energy saving and emission reduction in 2026 are 2.6 TWh and 2.1 million tons CO2eq, respectively.

  15. Light emission from compound eye with conformal fluorescent coating

    Science.gov (United States)

    Martín-Palma, Raúl J.; Miller, Amy E.; Pulsifer, Drew P.; Lakhtakia, Akhlesh

    2015-03-01

    Compound eyes of insects are attractive biological systems for engineered biomimicry as artificial sources of light, given their characteristic wide angular field of view. A blowfly eye was coated with a thin conformal fluorescent film, with the aim of achieving wide field-of-view emission. Experimental results showed that the coated eye emitted visible light and that the intensity showed a weaker angular dependence than a fluorescent thin film deposited on a flat surface.

  16. Light charged particle emission in 19F+12C reaction

    International Nuclear Information System (INIS)

    Bandyopadhyay, D.; Bhattacharya, C.; Krishan, K.; Bhattacharya, S.; Basu, S.K.; Chatterjee, A.; Kailas, S.; Singh, P.; Navin, A.; Shrivastava, A.; Samant, A.M.

    1997-01-01

    The light charged particle emission in the inverse kinematical reaction with 96 MeV 19 F beam on 12 C target have been studied experimentally. Light charged particles were detected in coincidence with the IMFs and ERs in three solid state telescopes in the angular range 10 deg-70 deg. The data of alpha particles in coincidence with the IMFs as well as with the ERs is reported

  17. Characterization and light emission from Erbium Oxide Nanoparticles

    Science.gov (United States)

    Maqbool, Muhammad; Wilkinson, Lynda; Ahmad, Iftikhar

    2013-03-01

    The present work reports light emission from Erbium Oxide nanoparticles. The nanoparticles, with 43 nm diameter, were obtained in the form of nanopowder with 99.9% purity. These nanoparticles were characterized for their light emission under a 532 nm Nd:YAG laser excitation. A Photoluminescence (PL) system was used to detect fluorescence emission from the nanoparticles. The PL system consisted of Pixis brand CCD camera with a range of 300 to 2000 nm. The Erbium Oxide nanoparticles were also mixed in distilled water to obtain spectrum. Two emission peaks were observed at 554 nm and 813 nm. The green emission at 554nm was obtained as a result of 4I15/2 --> 4S3/2 transition, and the near infrared emission from 4I15/2 --> 4I13/2 transition. The process was also repeated in vacuum and it was found that the green emission enhances tremendously when the nanoparticles are excited in vacuum. This enhanced luminescence from the Erbium Oxide nanoparticles shows their potential importance in the optical devices and Biomedical applications.

  18. Short-wavelength visible light emission from silicon nanocrystals

    Science.gov (United States)

    Pi, Xiaodong; Liptak, Rick; Campbell, Stephen; Kortshagen, Uwe

    2007-03-01

    Si is the material of choice for modern microelectronics but, as an indirect-bandgap semiconductor, it is not an efficient light emitter. An electrically pumped Si laser would present a breakthrough for optoelectronic integration that may enable optical interconnect to make computers faster. Si light emitting diodes may revolutionize solid-state lighting and displays because of the low cost and environmental friendliness of Si. One of the most challenging problems of Si-based lighting and displays is the lack of a reliable and efficient full visible spectrum emission. Si nanocrystals (Si-NCs) have so far been the most promising form of Si to emit light. Most of the synthesis approaches of Si-NCs, however, only lead to red light emission. Our recent work on Si-NCs synthesized by non-thermal plasmas has focused on extending their light emission into the short-wavelength range. Firstly, the process of oxidation-etching-oxidation of Si-NCs is investigated. This process causes the size of Si-NCs to decrease, leading to shorter wavelength light emission from Si-NCs. Yellow or green photoluminescence (PL) has been observed from initially oxidized red light emitting Si-NCs after HF vapour etching and atmospheric oxidation. The intensity of PL from Si-NCs, however, decreases by a factor up to 100. It is found that HF etching restructures the surface of Si-NCs. This leads to a decrease in the incorporation of O during subsequent oxidation, which finally results in silicon suboxide SiO1.9. Such an understoichiometry indicates a high density of defects such as Si dangling bonds at the Si-NC/oxide interface. Therefore, the PL efficiency is extremely low for short-wavelength light emitting Si-NCs obtained by the process of oxidation-etching-oxidation. Secondly, an integrated two-stage plasma system is employed to achieve the light emission from Si-NCs in the full visible spectrum range. Red-light-emitting Si-NCs are produced in the first stage by the plasma decomposition of SiH4

  19. A study on emission of light from fireworks

    Energy Technology Data Exchange (ETDEWEB)

    Yamamoto, Y.; Wada, Y. [Tokyo Univ., Dept, of Chemical Systems Engineering (Japan); Matsunaga, T.; Miyamoto, K.; Iida, M. [National Inst. of Materials and Chemical Research, Agency of Industrial Science and Technology, MITI (Japan); Arai, M.; Tamura, M. [Tokyo Univ., Inst. of Environmental Studies (Japan)

    2000-04-01

    Emission of light from burning fireworks was analyzed by spectroscopy using fireworks samples that contain HTPB fuel. Six color-emitting compositions of model and commercial fireworks were compared with each other ; results showed color-emission characteristics that were nearly identical. Red color-producing compositions which contained strontium salts were also investigated to clarify the mechanism of light emission. Results showed that color emission occurred as long as the pyrotechnic material contained elements necessary to form SrOH and SrCl in the flame, even in the absence of strontium chloride. The composition of the materials were shown to affect both the burning characteristics and the intensity of the red light emission. There is good agreement between the theoretical calculation of the adiabatic flame temperatures and concentrations and the experimental results achieved. It appeared possible to calculate the reddest composition and the ratio of spectral intensity of the color-emitting species by chemical equilibrium calculations. Thermal radiation proved to be the most effective in increasing the redness of the emitted spectrum. The chromaticity coordinates of the spectra from which the effect of heat radiation is removed are on the line between the point of SrOH and SrCl, meaning that the difference between the NH{sub 4}ClO{sub 4} composition and the KClO{sub 4} composition is the intensity ratio of SrOH. 3 tabs., 10 figs.

  20. Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tierno, S. P., E-mail: sp.tierno@upm.es; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L. [Department of Applied Physics, E.T.S.I. Aeronáutica y del Espacio. Universidad Politécnica de Madrid, 28040 Madrid (Spain)

    2016-01-15

    The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.

  1. Existence of a virtual cathode close to a strongly electron emissive wall in low density plasmas

    Science.gov (United States)

    Tierno, S. P.; Donoso, J. M.; Domenech-Garret, J. L.; Conde, L.

    2016-01-01

    The interaction between an electron emissive wall, electrically biased in a plasma, is revisited through a simple fluid model. We search for realistic conditions of the existence of a non-monotonic plasma potential profile with a virtual cathode as it is observed in several experiments. We mainly focus our attention on thermionic emission related to the operation of emissive probes for plasma diagnostics, although most conclusions also apply to other electron emission processes. An extended Bohm criterion is derived involving the ratio between the two different electron densities at the potential minimum and at the background plasma. The model allows a phase-diagram analysis, which confirms the existence of the non-monotonic potential profiles with a virtual cathode. This analysis shows that the formation of the potential well critically depends on the emitted electron current and on the velocity at the sheath edge of cold ions flowing from the bulk plasma. As a consequence, a threshold value of the governing parameter is required, in accordance to the physical nature of the electron emission process. The latter is a threshold wall temperature in the case of thermionic electrons. Experimental evidence supports our numerical calculations of this threshold temperature. Besides this, the potential well becomes deeper with increasing electron emission, retaining a fraction of the released current which limits the extent of the bulk plasma perturbation. This noninvasive property would explain the reliable measurements of plasma potential by using the floating potential method of emissive probes operating in the so-called strong emission regime.

  2. Emission of strong Terahertz pulses from laser wakefields in weakly coupled plasma

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Divya, E-mail: dsingh@rajdhani.du.ac.in [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India); Department of Physics & Electronics, Rajdhani College, University of Delhi, Raja Garden, Ring Road, New Delhi 110015 (India); Malik, Hitendra K. [PWAPA Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110 016 (India)

    2016-09-01

    The present paper discusses the laser plasma interaction for the wakefield excitation and the role of external magnetic field for the emission of Terahertz radiation in a collisional plasma. Flat top lasers are shown to be more appropriate than the conventional Gaussian lasers for the effective excitation of wakefields and hence, the generation of strong Terahertz radiation through the transverse component of wakefield.

  3. Characteristics of electron emission from PZT ferroelectric cathode under strong accelerating field

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, Yasushi [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan)]. E-mail: hayashi@es.titech.ac.jp; Hotta, Eiki [Department of Energy Sciences, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama (Japan); Flechtner, Donald [High Voltage Laboratory, Cornell University, Ithaca, NY (United States)

    2002-02-07

    We have studied emission characteristics of a PZT ferroelectric cathode under the influence of a strong accelerating field by varying the triggering conditions. The beam current pulse reveals a rising and a steady phase. In the rising phase, the time variation of the beam current is found to be linearly dependent on both the trigger voltage and the diode voltage at the time when the current starts. In the steady phase, field emission characteristics are observed. The results show that the diode voltage is not only accelerating the emitted electrons but also assisting the electron emission from the ferroelectric cathode. An empirical model is proposed and is found to yield a reasonable beam current pulse when the electric field on the surface of the cathode is uniformly distributed. It also provides us with a new possibility to diagnose the emission process of a ferroelectric electron gun. (author)

  4. Capturing triplet emission in white organic light emitting devices

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [Faculty of EHSE, School of Engineering and IT, B-purple-12, Charles Darwin University, Darwin, NT 0909 (Australia)

    2011-08-15

    The state-of-the art in the white organic light emitting devices (WOLEDs) is reviewed for further developments with a view to enhance the capture of triplet emission. In particular, applying the new exciton-spin-orbit-photon interaction operator as a perturbation, rates of spontaneous emission are calculated in a few phosphorescent materials and compared with experimental results. For iridium based phosphorescent materials the rates agree quite well with the experimental results. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Fabrication, Light Emission, and Magnetism of Silica Nanoparticles Hybridized with AIE Luminogens and Inorganic Nanostructures

    Science.gov (United States)

    Faisal, Mahtab

    Much research efforts have been devoted in developing new synthetic approaches for fluorescent silica nanoparticles (FSNPs) due to their potential high-technological applications. However, light emissions from most of the FSNPs prepared so far have been rather weak. This is due to the emission quenching caused by the aggregation of fluorophores in the solid state. We have observed a novel phenomenon of aggregation-induced emission (AIE): a series of propeller-shaped molecules such as tetraphenylethene (TPE) and silole are induced to emit efficiently by aggregate formation. Thus, they are ideal fluorophors for the construction of FSNPs and my thesis work focuses on the synthesis of silica nanoparticles containing these luminogens and magnetic nanostructures. Highly emissive FSNPs with core-shell structures are fabricated by surfactant-free sol-gel reactions of tetraphenylethene- (TPE) and silole-functionalized siloxanes followed by the reactions with tetraethoxysilane. The FSNPs are uniformly sized, surface-charged and colloidally stable. The diameters of the FSNPs are tunable in the range of 45--295 nm by changing the reaction conditions. Whereas their TPE and silole precursors are non-emissive, the FSNPs emit strong visible lights, thanks to the novel aggregation-induced emission characteristics of the TPE and silole aggregates in the hybrid nanoparticles. The FSNPs pose no toxicity to living cells and can be utilized to selectively image cytoplasm of HeLa cells. Applying the same tool in the presence of citrate-coated magnetite nanoparticles, uniform magnetic fluorescent silica nanoparticles (MFSNPs) with smooth surfaces are fabricated. These particles exhibit appreciable surface charges and hence good colloidal stability. They are superparamagnetic, exhibiting no hysteresis at room temperature. UV irradiation of a suspension of MFSNPs in ethanol gives strong blue and green emissions. The MFSNPs can selectively stain the cytoplasmic regions of the living cells

  6. Room temperature strong light-matter coupling in three dimensional terahertz meta-atoms

    Energy Technology Data Exchange (ETDEWEB)

    Paulillo, B., E-mail: bruno.paulillo@u-psud.fr; Manceau, J.-M., E-mail: jean-michel.manceau@u-psud.fr; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Institut d' Electronique Fondamentale, Univ. Paris Sud, UMR8622 CNRS, 91405 Orsay (France); Li, L. H.; Davies, A. G.; Linfield, E. H. [School of Electronic and Electrical Engineering, University of Leeds, Woodhouse Lane, Leeds LS2 9JT (United Kingdom)

    2016-03-07

    We demonstrate strong light-matter coupling in three dimensional terahertz meta-atoms at room temperature. The intersubband transition of semiconductor quantum wells with a parabolic energy potential is strongly coupled to the confined circuital mode of three-dimensional split-ring metal-semiconductor-metal resonators that have an extreme sub-wavelength volume (λ/10). The frequency of these lumped-element resonators is controlled by the size and shape of the external antenna, while the interaction volume remains constant. This allows the resonance frequency to be swept across the intersubband transition and the anti-crossing characteristic of the strong light-matter coupling regime to be observed. The Rabi splitting, which is twice the Rabi frequency (2Ω{sub Rabi}), amounts to 20% of the bare transition at room temperature, and it increases to 28% at low-temperature.

  7. Environmentally Benign Technology for Efficient Warm-White Light Emission

    Science.gov (United States)

    Shen, Pin-Chun; Lin, Ming-Shiun; Lin, Ching-Fuh

    2014-06-01

    Nowadays efficient down conversion for white light emission is mainly based on rare-earth doped phosphors or cadmium-containing quantum dots. Although they exhibit high luminescence efficiency, the rare-earth mining and cadmium pollution have so far led to extremely high environmental cost, which conflicts the original purpose of pursuing efficient lighting. Here, we explore a new strategy to achieve efficient luminescence conversion based on polymer-decorated nanoparticles. The ZnO and Mn2+ doped ZnS nanoparticles are encapsulated by poly(9,9-di-n- hexylfluorenyl-2,7-diyl). The resultant core-shell nanocomposites then encompass three UV-to-visible luminescence conversion routes for photon emissions at blue, green, and orange colors, respectively. As a result, the color temperature is widely tunable (2100 K ~ 6000 K), so candle light or pure white light can be generated. The quantum yield up to 91% could also be achieved. Such rare-earth-element free nanocomposites give the bright perspectives for energy-saving, healthy, and environmentally benign lighting.

  8. Influence of local field on spontaneous light emission by nanoparticles

    DEFF Research Database (Denmark)

    Keller, Ole; Lozovski, V.; Iezhokin, I.

    2009-01-01

    A self-consistent approach based on the local-field concept has been proposed to calculate the direction patterns of light emission by nanoparticles with various shapes. The main idea of the method consists in constructing self-consistent equations for the electromagnetic field at any point of th...... demonstrated to interact as almost point dipoles at distances that exceed their linear dimensions. This fact can be used to substantiate applications of the dipole approximation to studying the optical properties of submonolayer molecular coatings.......A self-consistent approach based on the local-field concept has been proposed to calculate the direction patterns of light emission by nanoparticles with various shapes. The main idea of the method consists in constructing self-consistent equations for the electromagnetic field at any point...

  9. Characterization of heat emission of light-curing units.

    Science.gov (United States)

    Wahbi, Mohammed A; Aalam, F A; Fatiny, F I; Radwan, S A; Eshan, I Y; Al-Samadani, K H

    2012-04-01

    This study was designed to analyze the heat emissions produced by light-curing units (LCUs) of different intensities during their operation. The null hypothesis was that the tested LCUs would show no differences in their temperature rises. FIVE COMMERCIALLY AVAILABLE LCUS WERE TESTED: a "Flipo" plasma arc, "Cromalux 100" quartz-tungsten-halogen, "L.E. Demetron 1" second-generation light-emitting diode (LED), and "Blue Phase C5" and "UltraLume 5" third-generation LED LCUs. The intensity of each LCU was measured with two radiometers. The temperature rise due to illumination was registered with a type-K thermocouple, which was connected to a computer-based data acquisition system. Temperature changes were recorded in continues 10 and 20 s intervals up to 300 s. The Flipo (ARC) light source revealed the highest mean heat emission while the L.E. Demetron 1 LED showing the lowest mean value at 10 and 20 s exposure times. Moreover, Cromalux (QTH) recorded the second highest value for all intervals (12.71, 14.63, 14.60) of heat emission than Blue Phase C5 (LED) (12.25, 13.87, 13.69), interestingly at 20 s illumination for all intervals the highest results (18.15, 19.27, 20.31) were also recorded with Flipo (PAC) LCU, and the lowest (6.71, 5.97, 5.55) with L.E. Demetron 1 LED, while Blue Phase C5 (LED) recorded the second highest value at the 1st and 2nd 20 s intervals (14.12, 11.84, 10.18) of heat emission than Cromalux (QTH) (12.26, 11.43, 10.26). The speed of temperature or heat rise during the 10 and 20 s depends on light intensity of emitted light. However, the QTH LCU was investigated resulted in a higher temperature rise than LED curing units of the same power density. The PAC curing unit induced a significantly higher heat emission and temperature increase in all periods, and data were statistically different than the other tested groups (p < .05). LED (Blue Phase C5) was not statistically significant (p < .05) (at 10 s) than QTH units, also LED (Blue

  10. Influence of local field on spontaneous light emission by nanoparticles

    DEFF Research Database (Denmark)

    Keller, Ole; Lozovski, V.; Iezhokin, I.

    2009-01-01

    A self-consistent approach based on the local-field concept has been proposed to calculate the direction patterns of light emission by nanoparticles with various shapes. The main idea of the method consists in constructing self-consistent equations for the electromagnetic field at any point...... demonstrated to interact as almost point dipoles at distances that exceed their linear dimensions. This fact can be used to substantiate applications of the dipole approximation to studying the optical properties of submonolayer molecular coatings....

  11. Room temperature strong light-matter coupling in 3D THz meta-atoms (Conference Presentation)

    Science.gov (United States)

    Paulillo, Bruno; Manceau, Jean-Michel; Li, Lianhe; Linfield, Edmund; Colombelli, Raffaele

    2016-04-01

    We demonstrate strong light-matter coupling at room temperature in the terahertz (THz) spectral region using 3D meta-atoms with extremely sub-wavelength volumes. Using an air-bridge fabrication scheme, we have implemented sub-wavelength 3D THz micro-resonators that rely on suspended loop antennas connected to semiconductor-filled patch cavities. We have experimentally shown that they possess the functionalities of lumped LC resonators: their frequency response can be adjusted by independently tuning the inductance associated the antenna element or the capacitance provided by the metal-semiconductor-metal cavity. Moreover, the radiation coupling and efficiency can be engineered acting on the design of the loop antenna, similarly to conventional RF antennas. Here we take advantage of this rich playground in the context of cavity electrodynamics/intersubband polaritonics. In the strong light-matter coupling regime, a cavity and a two-level system exchange energy coherently at a characteristic rate called the vacuum Rabi frequency ΩR which is dominant with respect to all other loss mechanisms involved. The signature, in the frequency domain, is the appearance of a splitting between the bare cavity and material system resonances: the new states are called upper and a lower polariton branches. So far, most experimental demonstrations of strong light-matter interaction between an intersubband transition and a deeply sub-wavelength mode in the THz or mid-infrared ranges rely on wavelength-scale or larger resonators such as photonic crystals, diffractive gratings, dielectric micro-cavities or patch cavities. Lately, planar metamaterials have been used to enhance the light-matter interaction and strongly reduce the interaction volume by engineering the electric and magnetic resonances of the individual subwavelength constituents. In this contribution we provide evidence of strong coupling between a THz intersubband transition and an extremely sub-wavelength mode (≈λ/10

  12. Strong enhancement of light-matter interaction in graphene coupled to a photonic crystal nanocavity.

    Science.gov (United States)

    Gan, Xuetao; Mak, Kin Fai; Gao, Yuanda; You, Yumeng; Hatami, Fariba; Hone, James; Heinz, Tony F; Englund, Dirk

    2012-11-14

    We demonstrate a large enhancement in the interaction of light with graphene through coupling with localized modes in a photonic crystal nanocavity. Spectroscopic studies show that a single atomic layer of graphene reduces the cavity reflection by more than a factor of one hundred, while also sharply reducing the cavity quality factor. The strong interaction allows for cavity-enhanced Raman spectroscopy on subwavelength regions of a graphene sample. A coupled-mode theory model matches experimental observations and indicates significantly increased light absorption in the graphene layer. The coupled graphene-cavity system also enables precise measurements of graphene's complex refractive index.

  13. Fiber optic light collection system for scanning-tunneling-microscope-induced light emission.

    Science.gov (United States)

    Watkins, Neil J; Long, James P; Kafafi, Zakya H; Mäkinen, Antti J

    2007-05-01

    We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

  14. Strong geologic methane emissions from discontinuous terrestrial permafrost in the Mackenzie Delta, Canada.

    Science.gov (United States)

    Kohnert, Katrin; Serafimovich, Andrei; Metzger, Stefan; Hartmann, Jörg; Sachs, Torsten

    2017-07-19

    Arctic permafrost caps vast amounts of old, geologic methane (CH 4 ) in subsurface reservoirs. Thawing permafrost opens pathways for this CH 4 to migrate to the surface. However, the occurrence of geologic emissions and their contribution to the CH 4 budget in addition to recent, biogenic CH 4 is uncertain. Here we present a high-resolution (100 m × 100 m) regional (10,000 km²) CH 4 flux map of the Mackenzie Delta, Canada, based on airborne CH 4 flux data from July 2012 and 2013. We identify strong, likely geologic emissions solely where the permafrost is discontinuous. These peaks are 13 times larger than typical biogenic emissions. Whereas microbial CH 4 production largely depends on recent air and soil temperature, geologic CH 4 was produced over millions of years and can be released year-round provided open pathways exist. Therefore, even though they only occur on about 1% of the area, geologic hotspots contribute 17% to the annual CH 4 emission estimate of our study area. We suggest that this share may increase if ongoing permafrost thaw opens new pathways. We conclude that, due to permafrost thaw, hydrocarbon-rich areas, prevalent in the Arctic, may see increased emission of geologic CH 4 in the future, in addition to enhanced microbial CH 4 production.

  15. Strong light-matter coupling from atoms to solid-state systems

    CERN Document Server

    2014-01-01

    The physics of strong light-matter coupling has been addressed in different scientific communities over the last three decades. Since the early eighties, atoms coupled to optical and microwave cavities have led to pioneering demonstrations of cavity quantum electrodynamics, Gedanken experiments, and building blocks for quantum information processing, for which the Nobel Prize in Physics was awarded in 2012. In the framework of semiconducting devices, strong coupling has allowed investigations into the physics of Bose gases in solid-state environments, and the latter holds promise for exploiting light-matter interaction at the single-photon level in scalable architectures. More recently, impressive developments in the so-called superconducting circuit QED have opened another fundamental playground to revisit cavity quantum electrodynamics for practical and fundamental purposes. This book aims at developing the necessary interface between these communities, by providing future researchers with a robust conceptu...

  16. A Strong Limit on the Very-high-energy Emission from GRB 150323A

    Science.gov (United States)

    Abeysekara, A. U.; Archer, A.; Benbow, W.; Bird, R.; Brose, R.; Buchovecky, M.; Bugaev, V.; Connolly, M. P.; Cui, W.; Errando, M.; Falcone, A.; Feng, Q.; Finley, J. P.; Flinders, A.; Fortson, L.; Furniss, A.; Gillanders, G. H.; Hütten, M.; Hanna, D.; Hervet, O.; Holder, J.; Hughes, G.; Humensky, T. B.; Johnson, C. A.; Kaaret, P.; Kar, P.; Kelley-Hoskins, N.; Kertzman, M.; Kieda, D.; Krause, M.; Krennrich, F.; Lang, M. J.; Lin, T. T. Y.; Maier, G.; McArthur, S.; Moriarty, P.; Mukherjee, R.; O’Brien, S.; Ong, R. A.; Park, N.; Perkins, J. S.; Petrashyk, A.; Pohl, M.; Popkow, A.; Pueschel, E.; Quinn, J.; Ragan, K.; Reynolds, P. T.; Richards, G. T.; Roache, E.; Rulten, C.; Sadeh, I.; Santander, M.; Sembroski, G. H.; Shahinyan, K.; Tyler, J.; Wakely, S. P.; Weiner, O. M.; Weinstein, A.; Wells, R. M.; Wilcox, P.; Wilhelm, A.; Williams, D. A.; Zitzer, B.; VERITAS Collaboration; Vurm, Indrek; Beloborodov, Andrei

    2018-04-01

    On 2015 March 23, the Very Energetic Radiation Imaging Telescope Array System (VERITAS) responded to a Swift-Burst Alert Telescope (BAT) detection of a gamma-ray burst, with observations beginning 270 s after the onset of BAT emission, and only 135 s after the main BAT emission peak. No statistically significant signal is detected above 140 GeV. The VERITAS upper limit on the fluence in a 40-minute integration corresponds to about 1% of the prompt fluence. Our limit is particularly significant because the very-high-energy (VHE) observation started only ∼2 minutes after the prompt emission peaked, and Fermi-Large Area Telescope observations of numerous other bursts have revealed that the high-energy emission is typically delayed relative to the prompt radiation and lasts significantly longer. Also, the proximity of GRB 150323A (z = 0.593) limits the attenuation by the extragalactic background light to ∼50% at 100–200 GeV. We conclude that GRB 150323A had an intrinsically very weak high-energy afterglow, or that the GeV spectrum had a turnover below ∼100 GeV. If the GRB exploded into the stellar wind of a massive progenitor, the VHE non-detection constrains the wind density parameter to be A ≳ 3 × 1011 g cm‑1, consistent with a standard Wolf–Rayet progenitor. Alternatively, the VHE emission from the blast wave would be weak in a very tenuous medium such as the interstellar medium, which therefore cannot be ruled out as the environment of GRB 150323A.

  17. Relativistic quantum dynamics in strong fields: Photon emission from heavy, few-electron ions

    International Nuclear Information System (INIS)

    Fritzsche, S.; Stoehlker, T.

    2005-03-01

    Recent progress in the study of the photon emission from highly-charged heavy ions is reviewed. These investigations show that high-Z ions provide a unique tool for improving the understanding of the electron-electron and electron-photon interaction in the presence of strong fields. Apart from the bound-state transitions, which are accurately described in the framework of quantum electrodynamics, much information has been obtained also from the radiative capture of (quasi-) free electrons by high-Z ions. Many features in the observed spectra hereby confirm the inherently relativistic behavior of even the simplest compound quantum systems in nature. (orig.)

  18. Experimental studies of light emission phenomena in superconducting RF cavities

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, P.L. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Delayen, J.R. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport, News, VA 23606 (United States); Center for Accelerator Science, Old Dominion University, Norfolk, VA, 23529 (United States); Fryberger, D., E-mail: fryberger@slac.stanford.ed [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States); Goree, W.S. [2G Enterprises, Pacific Grove, CA 93950 (United States); Mammosser, J. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport, News, VA 23606 (United States); Szalata, Z.M.; Weisend, J.G. [SLAC National Accelerator Laboratory, Menlo Park, CA 94025 (United States)

    2009-12-21

    Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from approx1/2 to approx2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW-controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects <=1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most perplexing aspect of this new mode was the observation of as many as seven luminous objects arrayed in what might be described as a macromolecular formation, coherently moving about in the interior of the cavity for extended periods of time, evidently without any wall contact. It is suggested that these mobile luminous objects are without explanation within the realm of established physics. Some remarks about more exotic theoretical possibilities are made, and future plans are discussed.

  19. Experimental Studies of Light Emission Phenomena in Superconducting RF Cavitites

    Energy Technology Data Exchange (ETDEWEB)

    Anthony, P.L.; /SLAC; Delayen, J.R.; /Jefferson Lab; Fryberger, D.; /SLAC; Goree, W.S.; Mammosser, J.; /Jefferson Lab /SNS Project, Oak Ridge; Szalata, Z.M.; II, J.G.Weisend /SLAC

    2009-08-04

    Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from {approx} 1/2 to {approx} 2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects {le} 1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most perplexing aspect of this new mode was the observation of as many as seven luminous objects arrayed in what might be described as a macromolecular formation, coherently moving about in the interior of the cavity for extended periods of time, evidently without any wall contact. It is suggested that these mobile luminous objects are without explanation within the realm of established physics. Some remarks about more exotic theoretical possibilities are made, and future plans are discussed.

  20. Experimental Study on Light Flash Radiant Intensity Generated by Strong Shock 2A12 Aluminum Plate

    Science.gov (United States)

    Tang, Enling; Zhang, Lijiao; Zhang, Qingming; Shi, Xiaohan; Wang, Meng; Wang, Di; Xiang, Shenghai; Xia, Jin; Han, Yafei; Xu, Mingyang; Wu, Jin; Zhang, Shuang; Yuan, Jianfei

    2015-07-01

    In order to study the light flash radiant intensity produced by strong shock on a 2A12 aluminum target at the same projectile incidence angles and different shock velocities, experimental measurements were conducted for light flash phenomena of a 2A12 aluminum projectile impacting a 2A12 aluminum target under the conditions of different impact velocity and the same projectile incidence angles of 45° by using an optical pyrometer measurement system and a two-stage light gas gun loading system. Experimental results show that the peak values of the light flash radiant intensity for the wavelength of 550 nm are largest in the wavelength ranges of 600 nm, 650 nm and 700 nm when a 2A12 aluminum projectile impacts a double-layer 2A12 aluminum plate in the present experimental conditions. supported by National Natural Science Foundation of China (Nos. 10972145, 11272218, 11472178), State Key Program of National Natural Science of China (No. 11032003), Program for Liaoning Excellent Talents in University, China (No. LR2013008)

  1. Quantum physics of light and matter photons, atoms, and strongly correlated systems

    CERN Document Server

    Salasnich, Luca

    2017-01-01

    This compact but exhaustive textbook, now in its significantly revised and expanded second edition, provides an essential introduction to the field quantization of light and matter with applications to atomic physics and strongly correlated systems. Following an initial review of the origins of special relativity and quantum mechanics, individual chapters are devoted to the second quantization of the electromagnetic field and the consequences of light field quantization for the description of electromagnetic transitions. The spin of the electron is then analyzed, with particular attention to its derivation from the Dirac equation. Subsequent topics include the effects of external electric and magnetic fields on the atomic spectra and the properties of systems composed of many interacting identical particles. The book also provides a detailed explanation of the second quantization of the non-relativistic matter field, i.e., the Schrödinger field, which offers a powerful tool for the investigation of many-body...

  2. Strong constraints on self-interacting dark matter with light mediators

    International Nuclear Information System (INIS)

    Bringmann, Torsten; Walia, Parampreet

    2017-04-01

    Coupling dark matter to light new particles is an attractive way to combine thermal production with strong velocity-dependent self-interactions. Here we point out that in such models the dark matter annihilation rate is generically enhanced by the Sommerfeld effect, and we derive the resulting constraints from the Cosmic Microwave Background and other indirect detection probes. For the frequently studied case of s-wave annihilation these constraints exclude the entire parameter space where the self-interactions are large enough to address the small-scale problems of structure formation.

  3. The first detection of neutral hydrogen in emission in a strong spiral lens

    Science.gov (United States)

    Lipnicky, Andrew; Chakrabarti, Sukanya; Wright, Melvyn C. H.; Blitz, Leo; Heiles, Carl; Cotton, William; Frayer, David; Blandford, Roger; Shu, Yiping; Bolton, Adam S.

    2018-05-01

    We report H I observations of eight spiral galaxies that are strongly lensing background sources. Our targets were selected from the Sloan WFC (Wide Field Camera) Edge-on Late-type Lens Survey (SWELLS) using the Arecibo, Karl G. Jansky Very Large Array, and Green Bank telescopes. We securely detect J1703+2451 at z = 0.063 with a signal-to-noise ratio of 6.7 and W50 = 79 ± 13 km s-1, obtaining the first detection of H I emission in a strong spiral lens. We measure a mass of M_{H I} = (1.77± 0.06^{+0.35}_{-0.75})× 10^9 M_{⊙} for this source. We find that this lens is a normal spiral, with observable properties that are fairly typical of spiral galaxies. For three other sources, we did not secure a detection; however, we are able to place strong constraints on the H I masses of those galaxies. The observations for four of our sources were rendered unusable due to strong radio frequency interference.

  4. The First Detection of Neutral Hydrogen in Emission in a Strong Spiral Lens

    Science.gov (United States)

    Lipnicky, Andrew; Chakrabarti, Sukanya; Wright, Melvyn C. H.; Blitz, Leo; Heiles, Carl; Cotton, William; Frayer, David; Blandford, Roger; Shu, Yiping; Bolton, Adam S.

    2018-02-01

    We report H I observations of eight spiral galaxies that are strongly lensing background sources. Our targets were selected from the Sloan WFC (Wide Field Camera) Edge-on Late-type Lens Survey (SWELLS) using the Arecibo, Karl G. Jansky Very Large Array, and Green Bank telescopes. We securely detect J1703+2451 at z = 0.063 with a signal-to-noise of 6.7 and W50 = 79 ± 13 km s-1, obtaining the first detection of H I emission in a strong spiral lens. We measure a mass of M_{H I}= (1.77± 0.06^{+0.35}_{-0.75})× 10^9 {M}_{\\odot} for this source. We find that this lens is a normal spiral, with observable properties that are fairly typical of spiral galaxies. For three other sources we did not secure a detection; however, we are able to place strong constraints on the H I masses of those galaxies. The observations for four of our sources were rendered unusable due to strong radio frequency interference.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-15

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

  6. STRONG FIELD EFFECTS ON EMISSION LINE PROFILES: KERR BLACK HOLES AND WARPED ACCRETION DISKS

    International Nuclear Information System (INIS)

    Wang Yan; Li Xiangdong

    2012-01-01

    If an accretion disk around a black hole is illuminated by hard X-rays from non-thermal coronae, fluorescent iron lines will be emitted from the inner region of the accretion disk. The emission line profiles will show a variety of strong field effects, which may be used as a probe of the spin parameter of the black hole and the structure of the accretion disk. In this paper, we generalize the previous relativistic line profile models by including both the black hole spinning effects and the non-axisymmetries of warped accretion disks. Our results show different features from the conventional calculations for either a flat disk around a Kerr black hole or a warped disk around a Schwarzschild black hole by presenting, at the same time, multiple peaks, rather long red tails, and time variations of line profiles with the precession of the disk. We show disk images as seen by a distant observer, which are distorted by the strong gravity. Although we are primarily concerned with the iron K-shell lines in this paper, the calculation is general and is valid for any emission lines produced from a warped accretion disk around a black hole.

  7. Suppression of Hydrogen Emission in an X-class White-light Solar Flare

    Energy Technology Data Exchange (ETDEWEB)

    Procházka, Ondrej; Milligan, Ryan O.; Mathioudakis, Mihalis [Astrophysics Research Centre, Queen’s University Belfast, Northern Ireland (United Kingdom); Allred, Joel C. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Kowalski, Adam F. [Department of Astrophysical and Planetary Sciences, University of Colorado Boulder, 2000 Colorado Avenue, Boulder, CO 80305 (United States); Kotrč, Pavel, E-mail: oprochazka01@qub.ac.uk [Astronomical Institute, The Czech Academy of Sciences, 25165 Ondřejov (Czech Republic)

    2017-03-01

    We present unique NUV observations of a well-observed X-class flare from NOAA 12087 obtained at the Ondřejov Observatory. The flare shows a strong white-light continuum but no detectable emission in the higher Balmer and Lyman lines. Reuven Ramaty High-Energy Solar Spectroscopic Imager and Fermi observations indicate an extremely hard X-ray spectrum and γ -ray emission. We use the RADYN radiative hydrodynamic code to perform two types of simulations: one where an energy of 3 × 10{sup 11} erg cm{sup −2} s{sup −1} is deposited by an electron beam with a spectral index of ≈3, and a second where the same energy is applied directly to the photosphere. The combination of observations and simulations allows us to conclude that the white-light emission and the suppression or complete lack of hydrogen emission lines is best explained by a model where the dominant energy deposition layer is located in the lower layers of the solar atmosphere, rather than the chromosphere.

  8. Characteristics of black carbon emissions from in-use light-duty passenger vehicles.

    Science.gov (United States)

    Zheng, Xuan; Zhang, Shaojun; Wu, Ye; Zhang, K Max; Wu, Xian; Li, Zhenhua; Hao, Jiming

    2017-12-01

    Mitigating black carbon (BC) emissions from various combustion sources has been considered an urgent policy issue to address the challenges of climate change, air pollution and health risks. Vehicles contribute considerably to total anthropogenic BC emissions and urban BC concentrations. Compared with heavy-duty diesel vehicles, there is much larger uncertainty in BC emission factors for light-duty passenger vehicles (LDPVs), in particular for gasoline LDPVs, which warrants further studies. In this study, we employed the dynamometer and the Aethalometer (AE-51) to measure second-by-second BC emissions from eight LDPVs by engine technology and driving cycle. The average BC emission factors under transient cycles (e.g., ECE-15, New European Driving Cycle, NEDC, Worldwide Harmonized Light Vehicles Test Cycle, WLTC) are 3.6-91.5 mg/km, 7.6 mg/km and 0.13-0.58 mg/km, respectively, for diesel (N = 3), gasoline direct injection (GDI) (N = 1) and gasoline port-fuel injection (PFI) engine categories (N = 4). For gasoline PFI LDPVs, the instantaneous emission profiles show a strong association of peak BC emissions with cold-start and high-speed aggressive driving. Such impacts lead to considerable BC emission contributions in cold-start periods (e.g., the first 47 s-94 s) over the entire cycle (e.g., 18-76% of the NEDC and 13-36% of the WLTC) and increased BC emission factors by 80-440% under the WLTC compared to the NEDC. For diesel BC emissions, the size distribution exhibits a typical unimodal pattern with one single peak appearing approximately from 120 to 150 nm, which is largely consistent with previous studies. Nevertheless, the average mass ratios of BC to particle mass (PM) range from 0.38 to 0.54 for three diesel samples, representing substantial impacts from both driving and engine conditions. The significant discrepancy between gasoline BC emission factors obtained from tailpipe exhaust versus ambient conditions suggest that more comparative

  9. Focusing light through strongly scattering media using genetic algorithm with SBR discriminant

    Science.gov (United States)

    Zhang, Bin; Zhang, Zhenfeng; Feng, Qi; Liu, Zhipeng; Lin, Chengyou; Ding, Yingchun

    2018-02-01

    In this paper, we have experimentally demonstrated light focusing through strongly scattering media by performing binary amplitude optimization with a genetic algorithm. In the experiments, we control 160 000 mirrors of digital micromirror device to modulate and optimize the light transmission paths in the strongly scattering media. We replace the universal target-position-intensity (TPI) discriminant with signal-to-background ratio (SBR) discriminant in genetic algorithm. With 400 incident segments, a relative enhancement value of 17.5% with a ground glass diffuser is achieved, which is higher than the theoretical value of 1/(2π )≈ 15.9 % for binary amplitude optimization. According to our repetitive experiments, we conclude that, with the same segment number, the enhancement for the SBR discriminant is always higher than that for the TPI discriminant, which results from the background-weakening effect of SBR discriminant. In addition, with the SBR discriminant, the diameters of the focus can be changed ranging from 7 to 70 μm at arbitrary positions. Besides, multiple foci with high enhancement are obtained. Our work provides a meaningful reference for the study of binary amplitude optimization in the wavefront shaping field.

  10. Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures

    Directory of Open Access Journals (Sweden)

    Mao-Kuo Wei

    2010-04-01

    Full Text Available In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode.

  11. Penning plasma based simultaneous light emission source of visible and VUV lights

    Energy Technology Data Exchange (ETDEWEB)

    Vyas, G. L., E-mail: glvyas27@gmail.com [Manipal University Jaipur (India); Prakash, R.; Pal, U. N. [CSIR-Central Electronics and Engineering Research Institute, Microwave Tubes Division (India); Manchanda, R. [Institute for Plasma Research (India); Halder, N. [Manipal University Jaipur (India)

    2016-06-15

    In this paper, a laboratory-based penning plasma discharge source is reported which has been developed in two anode configurations and is able to produce visible and VUV lights simultaneously. The developed source has simultaneous diagnostics facility using Langmuir probe and optical emission spectroscopy. The two anode configurations, namely, double ring and rectangular configurations, have been studied and compared for optimum use of the geometry for efficient light emissions and recording. The plasma is produced using helium gas and admixture of three noble gases including helium, neon, and argon. The source is capable to produce eight spectral lines for pure helium in the VUV range from 20 to 60 nm and total 24 spectral lines covering the wavelength range 20–106 nm for the admixture of gases. The large range of VUV lines is generated from gaseous admixture rather from the sputtered materials. The recorded spectrum shows that the plasma light radiations in both visible and VUV range are larger in double ring configuration than that of the rectangular configurations at the same discharge operating conditions. To clearly understand the difference, the imaging of the discharge using ICCD camera and particle-in-cell simulation using VORPAL have also been carried out. The effect of ion diffusion, metastable collision with the anode wall and the nonlinear effects are correlated to explain the results.

  12. Non-classical light emission from single conjugated polymers

    Science.gov (United States)

    Hollars, Christopher; Lane, Stephen; Huser, Thomas

    2002-03-01

    Photon-antibunching from single, isolated molecules of collapsed-chain poly[2-methoxy,5-(2’-ethyl-hexyloxy)-p-phenylene-vinylene] (MEH-PPV) has been observed using confocal microscopy techniques. Efficient inter-segment energy transfer in collapsed-chain conjugated polymers leads to emission from an average of only 2-3 active sites on a polymer chain that is composed of hundreds of quasi-chromophores. These few centers consist of the segments with the lowest excitation energy and are supplied by the efficient light-harvesting and energy transfer of the surrounding higher-energy segments. This effect depends on the conformation of the polymer molecules, which is controlled by solvent polarity. These results provide new insight into the controversial photophysics of conjugated polymers and their application in optoelectronic devices.

  13. Hard X-ray PhotoEmission Spectroscopy of strongly correlated systems

    Science.gov (United States)

    Panaccione, Giancarlo; Offi, Francesco; Sacchi, Maurizio; Torelli, Piero

    2008-06-01

    Hard X-ray PhotoEmission Spectroscopy (HAXPES) is a new tool for the study of bulk electronic properties of solids using synchrotron radiation. We review recent achievements of HAXPES, with particular reference to the VOLPE project, showing that high energy resolution and bulk sensitivity can be obtained at kinetic energies of 6-8 keV. We present also the results of recent studies on strongly correlated materials, such as vanadium sesquioxide and bilayered manganites, revealing the presence of different screening properties in the bulk with respect to the surface. We discuss the relevant experimental features of the metal-insulator transition in these materials. To cite this article: G. Panaccione et al., C. R. Physique 9 (2008).

  14. Dissertation: Precompound Emission of Energetic Light Fragments in Spallation Reactions

    Energy Technology Data Exchange (ETDEWEB)

    Kerby, Leslie Marie [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-08-04

    Emission of light fragments (LF) from nuclear reactions is an open question. Different reaction mechanisms contribute to their production; the relative roles of each, and how they change with incident energy, mass number of the target, and the type and emission energy of the fragments is not completely understood. None of the available models are able to accurately predict emission of LF from arbitrary reactions. However, the ability to describe production of LF (especially at energies ≳ 30 MeV) from many reactions is important for different applications, such as cosmic-ray-induced Single Event Upsets (SEUs), radiation protection, and cancer therapy with proton and heavy-ion beams, to name just a few. The Cascade-Exciton Model (CEM) version 03.03 and the Los Alamos version of the Quark-Gluon String Model (LAQGSM) version 03.03 event generators in Monte Carlo N-Particle Transport Code version 6 (MCNP6) describe quite well the spectra of fragments with sizes up to ⁴He across a broad range of target masses and incident energies (up to ~ 5 GeV for CEM and up to ~ 1 TeV/A for LAQGSM). However, they do not predict the high energy tails of LF spectra heavier than ⁴He well. Most LF with energies above several tens of MeV are emitted during the precompound stage of a reaction. The current versions of the CEM and LAQGSM event generators do not account for precompound emission of LF larger than ⁴He. The aim of our work is to extend the precompound model in them to include such processes, leading to an increase of predictive power of LF-production in MCNP6. This entails upgrading the Modified Exciton Model currently used at the preequilibrium stage in CEM and LAQGSM. It also includes expansion and examination of the coalescence and Fermi break-up models used in the precompound stages of spallation reactions within CEM and LAQGSM. Extending our models to include emission of fragments heavier than ⁴He at the precompound stage has indeed provided results that have much

  15. Designing, Probing, and Stabilizing Exotic Fabry-Perot Cavities for Studying Strongly Correlated Light

    Science.gov (United States)

    Ryou, Albert

    Synthetic materials made of engineered quasiparticles are a powerful platform for studying manybody physics and strongly correlated systems due to their bottom-up approach to Hamiltonian modeling. Photonic quasiparticles called polaritons are particularly appealing since they inherit fast dynamics from light and strong interaction from matter. This thesis describes the experimental demonstration of cavity Rydberg polaritons, which are composite particles arising from the hybridization of an optical cavity with Rydberg EIT, as well as the tools for probing and stabilizing the cavity. We first describe the design, construction, and testing of a four-mirror Fabry-Perot cavity, whose small waist size on the order of 10 microns is comparable to the Rydberg blockade radius. By achieving strong coupling between the cavity photon and an atomic ensemble undergoing electromagnetically induced transparency (EIT), we observe the emergence of the dark-state polariton and characterize its single-body properties as well as the single-quantum nonlinearity. We then describe the implementation of a holographic spatial light modulator for exciting different transverse modes of the cavity, an essential tool for studying polariton-polariton scattering. For compensating optical aberrations, we employ a digital micromirror device (DMD), combining beam shaping with adaptive optics to produce diffraction-limited light. We quantitatively measure the purity of the DMD-produced Hermite-Gauss modes and confirm up to 99.2% efficiency. One application of the technique is to create Laguerre-Gauss modes, which have been used to probe synthetic Landau levels for photons in a twisted, nonplanar cavity. Finally, we describe the implementation of an FPGA-based FIR filter for stabilizing the cavity. We digitally cancel the acoustical resonances of the feedback-controlled mechanical system, thereby demonstrating an order-of-magnitude enhancement in the feedback bandwidth from 200 Hz to more than 2 k

  16. Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

    International Nuclear Information System (INIS)

    Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

  17. Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends Data

    Data.gov (United States)

    U.S. Environmental Protection Agency — The Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends report is the authoritative reference for carbon dioxide (CO2) emissions,...

  18. Light absorption and emission in nanowire array solar cells.

    Science.gov (United States)

    Kupec, Jan; Stoop, Ralph L; Witzigmann, Bernd

    2010-12-20

    Inorganic nanowires are under intense research for large scale solar power generation intended to ultimately contribute a substantial fraction to the overall power mix. Their unique feature is to allow different pathways for the light absorption and carrier transport. In this publication we investigate the properties of a nanowire array acting as a photonic device governed by wave-optical phenomena. We solve the Maxwell equations and calculate the light absorption efficiency for the AM1.5d spectrum and give recommendations on the design. Due to concentration of the incident sunlight at a microscopic level the absorptivity of nanowire solar cells can exceed the absorptivity of an equal amount of material used in thin-film devices. We compute the local density of photon states to assess the effect of emission enhancement, which influences the radiative lifetime of excess carriers. This allows us to compute the efficiency limit within the framework of detailed balance. The efficiency is highly sensitive with respect to the diameter and distance of the nanowires. Designs featuring nanowires below a certain diameter will intrinsically feature low short-circuit current that cannot be compensated even by increasing the nanowire density. Optimum efficiency is not achieved in densely packed arrays, in fact spacing the nanowires further apart (simultaneously decreasing the material use) can even improve efficiency in certain scenarios. We observe absorption enhancement reducing the material use. In terms of carrier generation per material use, nanowire devices can outperform thin-film devices by far.

  19. Voltage-Controlled Switching of Strong Light-Matter Interactions using Liquid Crystals.

    Science.gov (United States)

    Hertzog, Manuel; Rudquist, Per; Hutchison, James A; George, Jino; Ebbesen, Thomas W; Börjesson, Karl

    2017-12-22

    We experimentally demonstrate a fine control over the coupling strength of vibrational light-matter hybrid states by controlling the orientation of a nematic liquid crystal. Through an external voltage, the liquid crystal is seamlessly switched between two orthogonal directions. Using these features, for the first time, we demonstrate electrical switching and increased Rabi splitting through transition dipole moment alignment. The C-N str vibration on the liquid crystal molecule is coupled to a cavity mode, and FT-IR is used to probe the formed vibropolaritonic states. A switching ratio of the Rabi splitting of 1.78 is demonstrated between the parallel and the perpendicular orientation. Furthermore, the orientational order increases the Rabi splitting by 41 % as compared to an isotropic liquid. Finally, by examining the influence of molecular alignment on the Rabi splitting, the scalar product used in theoretical modeling between light and matter in the strong coupling regime is verified. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Harmonic radiation emission from periodic lattices irradiated by short-pulse elliptically polarized laser light.

    Science.gov (United States)

    Ondarza-Rovira, R; Boyd, T J

    2001-10-01

    Radiated emission at high-order harmonic numbers is observed from thin crystalline layers irradiated by short femtosecond elliptically polarized laser light. The applied external radiation field drives the free electrons in the material to large oscillation amplitudes and harmonics are generated by the electronic response to the periodic lattice potential. A model was modified by introducing a more general expression for the lattice force that by sharpening or by smoothing the potential in turn allows the strength of the electronic perturbation to be varied. The electron motion is computed numerically by solving the electromagnetic force equation and by regarding the lattice potential as a perturbative source. For linearly polarized laser light the radiation spectra are characterized by emission lines forming a flat plateau in the region of low harmonic orders with a sharp cutoff for higher numbers. For circular polarization strong emission is found for two harmonic numbers, the first in the low-harmonic region and the second around the cutoff. By solving analytically the electron motion in an elliptically polarized laser field, an exact expression for the electron displacement in all three spatial directions is found. The amplitude of the oscillations sets the analytic form for calculating the peak harmonic numbers emitted from the laser-lattice interaction. The radiation effect studied here, if detected, might hold some potential as a diagnostic and could be used, in principle, as a method for determining the lattice parameter in crystalline structures.

  1. Oblique S and T constraints on electroweak strongly-coupled models with a light Higgs

    Energy Technology Data Exchange (ETDEWEB)

    Pich, A. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Rosell, I. [Departament de Física Teòrica, IFIC, Universitat de València - CSIC,Apt. Correus 22085, E-46071 València (Spain); Departamento de Ciencias Físicas, Matemáticas y de la Computación,Universidad CEU Cardenal Herrera,c/ Sant Bartomeu 55, E-46115 Alfara del Patriarca, València (Spain); Sanz-Ciller, J.J. [Departamento de Física Teórica, Instituto de Física Teórica,Universidad Autónoma de Madrid - CSIC,c/ Nicolás Cabrera 13-15, E-28049 Cantoblanco, Madrid (Spain)

    2014-01-28

    Using a general effective Lagrangian implementing the chiral symmetry breaking SU(2){sub L}⊗SU(2){sub R}→SU(2){sub L+R}, we present a one-loop calculation of the oblique S and T parameters within electroweak strongly-coupled models with a light scalar. Imposing a proper ultraviolet behaviour, we determine S and T at next-to-leading order in terms of a few resonance parameters. The constraints from the global fit to electroweak precision data force the massive vector and axial-vector states to be heavy, with masses above the TeV scale, and suggest that the W{sup +}W{sup −} and ZZ couplings of the Higgs-like scalar should be close to the Standard Model value. Our findings are generic, since they only rely on soft requirements on the short-distance properties of the underlying strongly-coupled theory, which are widely satisfied in more specific scenarios.

  2. 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.

  3. Enhanced light emission in blue light-emitting diodes by multiple Mie scattering from embedded silica nanosphere stacking layers.

    Science.gov (United States)

    Park, Young Jae; Kang, Ji Hye; Kim, Hee Yun; Lysak, Volodymyr V; Chandramohan, S; Ryu, Jae Hyoung; Kim, Hyun Kyu; Han, Nam; Jeong, Hyun; Jeong, Mun Seok; Hong, Chang-Hee

    2011-11-07

    We demonstrate enhanced light emission in blue light-emitting diodes (LEDs) by multiple Mie scattering from embedded silica nanosphere stacking layers (SNSL). A honeycomb cone structure is introduced in the GaN epilayer to confine a maximum number of silica nanospheres (SNs). We found that the light is predominantly directed vertically by scattering and geometrical effect in SNSL embedded LEDs. Consequently, the light output power is enhanced by 2.7 times, which we attribute to the improvement in light extraction efficiency due to the multiple Mie scattering of light from the embedded SNSL. The experimental results are verified by simulation using finite difference time domain method (FDTD).

  4. Isoprenoid emission response to changing light conditions of English oak, European beech and Norway spruce

    DEFF Research Database (Denmark)

    Van Meeningen, Ylva; Schurgers, Guy; Rinnan, Riikka

    2017-01-01

    Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis...... be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species. Light is an important environmental factor controlling biogenic...... improving emission models and to further emphasize the discussion regarding light or temperature dependencies for individual compounds across species. Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard...

  5. Problems related to stimulated electromagnetic emissions, strong turbulence and ionospheric modification

    International Nuclear Information System (INIS)

    Goodman, S.

    1993-05-01

    Optical pumping of the ionospheric plasma by high-frequency radio waves produces a state of turbulence. Several consequences of the pumping are considered in this thesis. At reflection altitude the plasma is thought to be dominated by parametric instabilities and strong turbulence; these are both encapsulated in the so called Zakharov equations. The Zakharov equations are derived and generalised from kinetic theory. Limits of validity, corrections to the ion sound speed,effective ponderomotive force, nonlinear damping and other generalisation are included. As an example of the difference a kinetic approach makes, the threshold for parametric instabilities is seen to be lowered in a kinetic plasma. Mostly relevant to the upper hybrid layer is the recent discovery in the pumping experiments of stimulated electromagnetic emissions (SEE). In particular one feature of SEE which occurs around the cyclotron harmonics and depends on density striations is investigated. The observed frequency of emission, dependency on striations, time evolution and cutoff frequency below which the feature does not occur, are explained. Two theoretical approaches are taken. The first is a parametric three wave decay instability followed by a nonlinear mixing to produce SEE. Thresholds for the instability are well within experimental capacity. The second, less orthodox, approach, is a finite amplitude model. The finite amplitude model goes beyond the traditional parametric approach by being able to predict radiated power output. Miscellaneous aspects of a turbulent ionosphere are also examined. The dependency of the scattering cross section of a turbulent plasma upon higher order perturbations is considered. In a turbulent plasma, density gradients steeper than characteristic plasma scales may develop. The case of calculating the dielectric permittivity for a linear gradient of arbitrary steepness is considered

  6. Strong photocurrent enhancements in plasmonic organic photovoltaics by biomimetic nanoarchitectures with efficient light harvesting.

    Science.gov (United States)

    Leem, Jung Woo; Kim, Sehwan; Park, Chihyun; Kim, Eunkyoung; Yu, Jae Su

    2015-04-01

    We propose the biomimetic moth-eye nanoarchitectures as a novel plasmonic light-harvesting structure for further enhancing the solar-generated photocurrents in organic photovoltaics (OPVs). The full moth-eye nanoarchitectures are composed of two-dimensional hexagonal periodic grating arrays on surfaces of both the front zinc oxide (ZnO) and rear active layers, which are prepared by a simple and cost-effective soft imprint nanopatterning technique. For the 380 nm period ZnO and 650 nm period active gratings (i.e., ZnO(P380)/Active(P650)), the poly(3-hexylthiophene-2,5-diyl):indene-C60 bis-adduct (P3HT:ICBA)-based plasmonic OPVs exhibit an improvement of the absorption spectrum compared to the pristine OPVs over a broad wavelength range of 350-750 nm, showing absorption enhancement peaks at wavelengths of ∼370, 450, and 670 nm, respectively. This leads to a considerable increase of short-circuit current density (Jsc) from 10.9 to 13.32 mA/cm(2), showing a large Jsc enhancement percentage of ∼22.2%. As a result, the strongly improved power conversion efficiency (PCE) of 6.28% is obtained compared to that (i.e., PCE = 5.12%) of the pristine OPVs. For the angle-dependent light-absorption characteristics, the plasmonic OPVs with ZnO(P380)/Active(P650) have a better absorption performance than that of the pristine OPVs at incident angles of 20-70°. For optical absorption characteristics and near-field intensity distributions of plasmonic OPVs, theoretical analyses are also performed by a rigorous coupled-wave analysis method, which gives a similar tendency with the experimentally measured data.

  7. THERMODYNAMICS OF LIGHT EMISSION AND FREE-ENERGY STORAGE INPHOTOSYNTHESIS

    Energy Technology Data Exchange (ETDEWEB)

    Ross, Robert T.; Calvin, Melvin

    1967-04-01

    A Planck law relationship between absorption and emission spectra is used to compute the fluorescence spectra of some photosynthetic systems from their absorption spectra. Calculated luminescence spectra of purple bacteria agree well but not perfectly with published experimental spectra. Application of the Planck law relation to published activation spectra for Systems I and II of spinach chloroplast permits independent calculation of the luminescence spectra of the two systems; if the luminescence yield of System I is taken to be one-third the yield of System II, then the combined luminescence spectrum closely fits published experimental measurement. Consideration of the entropy associated with the excited state of the absorbing molecules is used to compute the oxidation-reduction potentials and maximum free-energy storage resulting from light absorption. Spinach chloroplasts under an illumination of 1 kilolux of white light can produce at most a potential difference of 1.32 eV for System I, and 1.36 eV for System II. In the absence of non-radiative losses, the maximum amount of free energy stored is 1.19 eV and 1.23 eV per photon absorbed for Systems I and II, respectively. The bacterium Chromatium under an illumination of 1 milliwatt/cm{sup 2} of Na D radiation can produce at most a potential difference of 0.90 eV; the maximum amount of free energy stored is 0.79 eV per photon absorbed. The combined effect of partial thermodynamic reversibility and a finite trapping rate on the amount of luminescence is considered briefly.

  8. Very Strong TeV Emission as $\\gamma$-Ray Burst Afterglows

    CERN Document Server

    Totani, T

    1998-01-01

    Gamma-ray bursts (GRBs) and following afterglows are considered to be produced by dissipation of kinetic energy of a relativistic fireball and radiation process is widely believed as synchrotron radiation or inverse Compton scattering of electrons. We argue that the transfer of kinetic energy of ejecta into electrons may be inefficient process and hence the total energy released by a GRB event is much larger than that emitted in soft gamma-rays, by a factor of \\sim (m_p/m_e). We show that, in this case, very strong emission of TeV gamma-rays is possible due to synchrotron radiation of protons accelerated up to \\sim 10^{21} eV, which are trapped in the magnetic field of afterglow shock and radiate their energy on an observational time scale of \\sim day. This suggests a possibility that GRBs are most energetic in TeV range and such TeV gamma-rays may be detectable from GRBs even at cosmological distances, i.e., z gives a quantitative explanation for the famous long-duration GeV photons detected from GRB940217. ...

  9. Delayed light emission of Tetraphenyl-butadiene excited by liquid argon scintillation light. Current status and future plans

    Science.gov (United States)

    Segreto, E.; Machado, A. A.; Araujo, W.; Teixeira, V.

    2016-02-01

    Tetraphenyl-butadiene is the wavelength shifter most widely used in combination with liquid argon. The latter emits scintillation photons with a wavelength of 127 nm that need to be downshifted to be detected by photomultipliers with glass or quartz windows. Tetraphenyl-butadiene has been demonstrated to have an extremely high conversion efficiency, possibly higher than 100% for 127 nm photons, while there is no precise information about the time dependence of its emission. It is usually assumed to be exponentially decaying with a characteristic time of the order of one ns, as an extrapolation from measurements with exciting radiation in the near UV . This work shows that tetraphenyl-butadiene, when excited by 127 nm photons, re-emits photons not only with a very short decay time, but also with slower ones due to triplet states de-excitations. This fact can strongly contribute to clarifying the anomalies in liquid-argon scintillation light reported in the literature since the 1970s. Precision measurements of the properties of TPB, when excited by Vacuum Ultra Violet photons are being carried on at the Brazilian Synchrotron Light Laboratory in Campinas (State of São Paulo).

  10. Spectral Analysis of the Light Flash Produced by a Natural Dolomite Plate Under Strong Shock

    International Nuclear Information System (INIS)

    Tang Enling; Xu Mingyang; Shi Xiaohan; Wang Meng; Wang Di; Xiang Shenghai; Xia Jin; Han Yafei; Zhang Lijiao; Wu Jin; Zhang Shuang; Yuan Jianfei; Zhang Qingming

    2015-01-01

    In order to obtain the elemental compositions of the projectile and target materials during 2A12 aluminum projectile shot on a natural dolomite plate, three kinds of experiments have been conducted using a spectral acquirement system established on a two-stage light gas gun for impact velocities ranging from 2.20 km/s to 4.20 km/s, at the same projectile incidence angle of 30°. Experimental results show that the elemental compositions of the projectile and target materials in the strong shock experiments have a good agreement with the original elemental compositions of the projectile and target. In addition, the relations between spectral radiant intensity and elemental compositions of the projectile and target materials have been obtained for different impact velocities, in which the spectral radiant intensity of the main elements in the material increases with increasing impact velocity, and more elements appear with increasing impact velocity since more energy would result from a higher velocity impact. (paper)

  11. 75 FR 7426 - Tier 2 Light-Duty Vehicle and Light-Duty Truck Emission Standards and Gasoline Sulfur Control...

    Science.gov (United States)

    2010-02-19

    ... 2060-AI23; 2060-AQ12 Tier 2 Light-Duty Vehicle and Light-Duty Truck Emission Standards and Gasoline.... The rulemaking also required oil refiners to limit the sulfur content of the gasoline they produce. Sulfur in gasoline has a detrimental impact on catalyst performance and the sulfur requirements have...

  12. Efficient light emitting devices based on phosphorescent partially doped emissive layers

    KAUST Repository

    Yang, Xiaohui

    2013-05-29

    We report efficient organic light emitting devices employing an ultrathin phosphor emissive layer. The electroluminescent spectra of these devices can be tuned by introducing a low-energy emitting phosphor layer into the emission zone. Devices with the emissive layer consisting of multiple platinum-complex/spacer layer cells show a peak external quantum efficiency of 18.1%, which is among the best EQE values for platinum-complex based light emitting devices. Devices with an ultrathin phosphor emissive layer show stronger luminance decay with the operating time compared to the counterpart devices having a host-guest emissive layer.

  13. Isoprenoid emission response to changing light conditions of English oak, European beech and Norway spruce

    Science.gov (United States)

    van Meeningen, Ylva; Schurgers, Guy; Rinnan, Riikka; Holst, Thomas

    2017-09-01

    Light is an important environmental factor controlling biogenic volatile organic compound (BVOC) emissions, but in natural conditions its impact is hard to separate from other influential factors such as temperature. We studied the light response of foliar BVOC emissions, photosynthesis and stomatal conductance on three common European tree species, namely English oak (Quercus robur), European beech (Fagus sylvatica) and two provenances of Norway spruce (Picea abies) in Taastrup, Denmark. Leaf scale measurements were performed on the lowest positioned branches of the tree in July 2015. Light intensity was increased in four steps (0, 500, 1000 and 1500 µmol m-2 s-1), whilst other chamber conditions such as temperature, humidity and CO2 levels were fixed. Whereas the emission rate differed between individuals of the same species, the relative contributions of compounds to the total isoprenoid emission remained similar. Whilst some compounds were species specific, the compounds α-pinene, camphene, 3-carene, limonene and eucalyptol were emitted by all of the measured tree species. Some compounds, like isoprene and sabinene, showed an increasing emission response with increasing light intensity, whereas other compounds, like camphene, had no significant emission response to light for most of the measured trees. English oak and European beech showed high light-dependent emission fractions from isoprene and sabinene, but other emitted compounds were light independent. For the two provenances of Norway spruce, the compounds α-pinene, 3-carene and eucalyptol showed high light-dependent fractions for many of the measured trees. This study highlights differences between compound emissions in their response to a change in light and a possible light independence for certain compounds, which might be valid for a wider range of tree species. This information could be of importance when improving emission models and to further emphasize the discussion regarding light or

  14. Strong Photonic-Band-Gap Effect on the Spontaneous Emission in 3D Lead Halide Perovskite Photonic Crystals.

    Science.gov (United States)

    Zhou, Xue; Li, Mingzhu; Wang, Kang; Li, Huizeng; Li, Yanan; Li, Chang; Yan, Yongli; Zhao, Yongsheng; Song, Yanlin

    2018-03-25

    Stimulated emission in perovskite-embedded polymer opal structures is investigated. A polymer opal structure is filled with a perovskite, and perovskite photonic crystals are prepared. The spontaneous emission of the perovskite embedded in the polymer opal structures exhibits clear signatures of amplified spontaneous emission (ASE) via gain modulation. The difference in refractive-index contrast between the perovskite and the polymer opal is large enough for retaining photonic-crystals properties. The photonic band gap has a strong effect on the fluorescence emission intensity and lifetime. The stimulated emission spectrum exhibits a narrow ASE rather than a wide fluorescence peak in the thin film. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. A STRONG EMISSION LINE NEAR 24.8 Angstrom-Sign IN THE X-RAY BINARY SYSTEM MAXI J0556-332: GRAVITATIONAL REDSHIFT OR UNUSUAL DONOR?

    Energy Technology Data Exchange (ETDEWEB)

    Maitra, Dipankar; Miller, Jon M.; Reynolds, Mark T. [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Raymond, John C., E-mail: dmaitra@umich.edu [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)

    2011-12-10

    We report the discovery of a strong emission line near 24.8 Angstrom-Sign (0.5 keV) in the newly discovered X-ray binary system MAXI J0556-332 with the reflection grating spectrometer (RGS) on board the XMM-Newton observatory. The X-ray light curve morphology during these observations is complex and shows occasional dipping behavior. Here we present time- and rate-selected spectra from the RGS and show that this strong emission line is unambiguously present in all the XMM observations. The measured line center is consistent with the Ly{alpha} transition of N VII in the rest frame. While the spectra contain imprints of absorption lines and edges, there appear to be no other significantly prominent narrow line due to the source itself, thus making the identification of the 24.8 Angstrom-Sign line uncertain. We discuss possible physical scenarios, including a gravitationally redshifted O VIII Ly{alpha} line originating at the surface of a neutron star or an unusual donor with an extremely high N/O abundance (>57) relative to solar that may have produced this comparatively strong emission line.

  16. Light-induced protein nitration and degradation with HONO emission

    Directory of Open Access Journals (Sweden)

    H. Meusel

    2017-10-01

    Full Text Available Proteins can be nitrated by air pollutants (NO2, enhancing their allergenic potential. This work provides insight into protein nitration and subsequent decomposition in the presence of solar radiation. We also investigated light-induced formation of nitrous acid (HONO from protein surfaces that were nitrated either online with instantaneous gas-phase exposure to NO2 or offline by an efficient nitration agent (tetranitromethane, TNM. Bovine serum albumin (BSA and ovalbumin (OVA were used as model substances for proteins. Nitration degrees of about 1 % were derived applying NO2 concentrations of 100 ppb under VIS∕UV illuminated conditions, while simultaneous decomposition of (nitrated proteins was also found during long-term (20 h irradiation exposure. Measurements of gas exchange on TNM-nitrated proteins revealed that HONO can be formed and released even without contribution of instantaneous heterogeneous NO2 conversion. NO2 exposure was found to increase HONO emissions substantially. In particular, a strong dependence of HONO emissions on light intensity, relative humidity, NO2 concentrations and the applied coating thickness was found. The 20 h long-term studies revealed sustained HONO formation, even when concentrations of the intact (nitrated proteins were too low to be detected after the gas exchange measurements. A reaction mechanism for the NO2 conversion based on the Langmuir–Hinshelwood kinetics is proposed.

  17. Strong mutagenic effects of diesel engine emissions using vegetable oil as fuel.

    Science.gov (United States)

    Bünger, Jürgen; Krahl, Jürgen; Munack, Axel; Ruschel, Yvonne; Schröder, Olaf; Emmert, Birgit; Westphal, Götz; Müller, Michael; Hallier, Ernst; Brüning, Thomas

    2007-08-01

    Diesel engine emissions (DEE) are classified as probably carcinogenic to humans. In recent years every effort was made to reduce DEE and their content of carcinogenic and mutagenic polycyclic aromatic compounds. Since 1995 we observed an appreciable reduction of mutagenicity of DEE driven by reformulated or newly designed fuels in several studies. Recently, the use of rapeseed oil as fuel for diesel engines is rapidly growing among German transportation businesses and agriculture due to economic reasons. We compared the mutagenic effects of DEE from two different batches of rapeseed oil (RSO) with rapeseed methyl ester (RME, biodiesel), natural gas derived synthetic fuel (gas-to-liquid, GTL), and a reference diesel fuel (DF). The test engine was a heavy-duty truck diesel running the European Stationary Cycle. Particulate matter from the exhaust was sampled onto PTFE-coated glass fibre filters and extracted with dichloromethane in a soxhlet apparatus. The gas phase constituents were sampled as condensates. The mutagenicity of the particle extracts and the condensates was tested using the Salmonella typhimurium/mammalian microsome assay with tester strains TA98 and TA100. Compared to DF the two RSO qualities significantly increased the mutagenic effects of the particle extracts by factors of 9.7 up to 59 in tester strain TA98 and of 5.4 up to 22.3 in tester strain TA100, respectively. The condensates of the RSO fuels caused an up to factor 13.5 stronger mutagenicity than the reference fuel. RME extracts had a moderate but significant higher mutagenic response in assays of TA98 with metabolic activation and TA100 without metabolic activation. GTL samples did not differ significantly from DF. In conclusion, the strong increase of mutagenicity using RSO as diesel fuel compared to the reference DF and other fuels causes deep concern on future usage of this biologic resource as a replacement of established diesel fuels.

  18. Plasmon-enhanced emission from optically-doped MOS light sources.

    Science.gov (United States)

    Hryciw, Aaron; Jun, Young Chul; Brongersma, Mark L

    2009-01-05

    We evaluate the spontaneous emission rate (Purcell) enhancement for optically-doped metal-dielectric-semiconductor light-emitting structures by considering the behavior of a semiclassical oscillating point dipole placed within the dielectric layer. For a Ag-SiO(2)-Si structure containing emitters at the center of a 20-nm-thick SiO(2) layer, spontaneous emission rate enhancements of 40 to 60 can be reached in the wavelength range of 600 to 1800 nm, far away from the surface plasmon resonance; similar enhancements are also possible if Al is used instead of Ag. For dipoles contained in the thin oxide layer of a Ag-SiO(2)-Si-SiO(2) structure, the emission exhibits strong preferential coupling to a single well-defined Si waveguide mode. This work suggests a means of designing a new class of power-efficient, high-modulation-speed, CMOS-compatible optical sources that take full advantage of the excellent electrical properties and plasmon-enhanced op cal properties afforded by MOS devices.

  19. Mechanically induced strong red emission in samarium ions doped piezoelectric semiconductor CaZnOS for dynamic pressure sensing and imaging

    Science.gov (United States)

    Wang, Wei; Peng, Dengfeng; Zhang, Hanlu; Yang, Xiaohong; Pan, Caofeng

    2017-07-01

    Piezoelectric semiconductor with optical, electrical and mechanical multifunctions has great potential applications in future optoelectronic devices. The rich properties and applications mainly encompass the intrinsic structures and their coupling effects. Here, we report that lanthanide ions doped piezoelectric semiconductor CaZnOS:Sm3+ showing strong red emission induced by dynamic mechanical stress. Under moderate mechanical load, the doped piezoelectric semiconductor exhibits strong visible red emission to the naked eyes even under the day light. A flexible dynamic pressure sensor device is fabricated based on the prepared CaZnOS:Sm3+ powders. The mechanical-induced emission properties of the device are investigated by the optical fiber spectrometer. The linear characteristic emissions are attributed to the 4G5/2→6H5/2 (566 nm), 4G5/2→6H7/2 (580-632 nm), 4G5/2→6H9/2 (653-673 nm) and 4G5/2→6H11/2 (712-735 nm) f-f transitions of Sm3+ ions. The integral emission intensity is proportional to the value of applied pressure. By using the linear relationship between integrated emission intensity and the dynamic pressure, the real-time pressure distribution is visualized and recorded. Our results highlight that the incorporation of lanthanide luminescent ions into piezoelectric semiconductors as smart materials could be applied into the flexible mechanical-optical sensor device without additional auxiliary power, which has great potential for promising applications such as mapping of personalized handwriting, smart display, and human machine interface.

  20. Quantitative analysis of directional spontaneous emission spectra from light sources in photonic crystals

    NARCIS (Netherlands)

    Nikolaev, I.; Lodahl, P.; Vos, Willem L.

    2005-01-01

    We have performed angle-resolved measurements of spontaneous-emission spectra from laser dyes and quantum dots in opal and inverse opal photonic crystals. Pronounced directional dependencies of the emission spectra are observed: angular ranges of strongly reduced emission adjoin with angular ranges

  1. Light vehicle regulated and unregulated emissions from different biodiesels

    International Nuclear Information System (INIS)

    Karavalakis, George; Stournas, Stamoulis; Bakeas, Evangelos

    2009-01-01

    In this study, the regulated and unregulated emissions profile and fuel consumption of an automotive diesel and biodiesel blends, prepared from two different biodiesels, were investigated. The biodiesels were a rapeseed methyl ester (RME) and a palm-based methyl ester (PME). The tests were performed on a chassis dynamometer with constant volume sampling (CVS) over the New European Driving Cycle (NEDC) and the non-legislated Athens Driving Cycle (ADC), using a Euro 2 compliant passenger vehicle. The objectives were to evaluate the impact of biodiesel chemical structure on the emissions, as well as the influence of the applied driving cycle on the formation of exhaust emissions and fuel consumption. The results showed that NOx emissions were influenced by certain biodiesel properties, such as those of cetane number and iodine number. NOx emissions followed a decreasing trend over both cycles, where the most beneficial reduction was obtained with the application of the more saturated biodiesel. PM emissions were decreased with the palm-based biodiesel blends over both cycles, with the exception of the 20% blend which was higher compared to diesel fuel. PME blends led to increases in PM emissions over the ADC. The majority of the biodiesel blends showed a tendency for lower CO and HC emissions. The differences in CO2 emissions were not statistically significant. Fuel consumption presented an increase with both biodiesels. Total PAH and nitro-PAH emission levels were decreased with the use of biodiesel independently of the source material. Lower molecular weight PAHs were predominant in both gaseous and particulate phases. Both biodiesels had a negative impact on certain carbonyl emissions. Formaldehyde and acetaldehyde were the dominant aldehydes emitted from both fuels.

  2. Light vehicle regulated and unregulated emissions from different biodiesels.

    Science.gov (United States)

    Karavalakis, George; Stournas, Stamoulis; Bakeas, Evangelos

    2009-05-01

    In this study, the regulated and unregulated emissions profile and fuel consumption of an automotive diesel and biodiesel blends, prepared from two different biodiesels, were investigated. The biodiesels were a rapeseed methyl ester (RME) and a palm-based methyl ester (PME). The tests were performed on a chassis dynamometer with constant volume sampling (CVS) over the New European Driving Cycle (NEDC) and the non-legislated Athens Driving Cycle (ADC), using a Euro 2 compliant passenger vehicle. The objectives were to evaluate the impact of biodiesel chemical structure on the emissions, as well as the influence of the applied driving cycle on the formation of exhaust emissions and fuel consumption. The results showed that NO(x) emissions were influenced by certain biodiesel properties, such as those of cetane number and iodine number. NO(x) emissions followed a decreasing trend over both cycles, where the most beneficial reduction was obtained with the application of the more saturated biodiesel. PM emissions were decreased with the palm-based biodiesel blends over both cycles, with the exception of the 20% blend which was higher compared to diesel fuel. PME blends led to increases in PM emissions over the ADC. The majority of the biodiesel blends showed a tendency for lower CO and HC emissions. The differences in CO(2) emissions were not statistically significant. Fuel consumption presented an increase with both biodiesels. Total PAH and nitro-PAH emission levels were decreased with the use of biodiesel independently of the source material. Lower molecular weight PAHs were predominant in both gaseous and particulate phases. Both biodiesels had a negative impact on certain carbonyl emissions. Formaldehyde and acetaldehyde were the dominant aldehydes emitted from both fuels.

  3. Unprecedentedly strong and narrow electromagnetic emissions stimulated by high-frequency radio waves in the ionosphere.

    Science.gov (United States)

    Norin, L; Leyser, T B; Nordblad, E; Thidé, B; McCarrick, M

    2009-02-13

    Experimental results of secondary electromagnetic radiation, stimulated by high-frequency radio waves irradiating the ionosphere, are reported. We have observed emission peaks, shifted in frequency up to a few tens of Hertz from radio waves transmitted at several megahertz. These emission peaks are by far the strongest spectral features of secondary radiation that have been reported. The emissions are attributed to stimulated Brillouin scattering, long predicted but hitherto never unambiguously identified in high-frequency ionospheric interaction experiments. The experiments were performed at the High-Frequency Active Auroral Research Program (HAARP), Alaska, USA.

  4. Stability of the Light Output, Oral Cavity Tip Accessibility in Posterior Region and Emission Spectrum of Light-Curing Units.

    Science.gov (United States)

    André, C B; Nima, G; Sebold, M; Giannini, M; Price, R B

    2018-04-09

    This study evaluated the light output from six light-emitting diode dental curing lights after 25 consecutive light exposures without recharging the battery, tip accessibility in the posterior region, and light beam spread from light-curing units. Irradiance, spectral peak, and radiant exposure were measured with the battery fully charged (Bluephase Style, ESPE Cordless, Elipar S10, Demi Ultra, Valo Cordless, and Radii-Cal) and monitored for 25 light exposures (each lasting 10 seconds). The tip diameter was measured to identify the beam size and the ability of the six light-curing units to irradiate all areas of the lower second molar in the standard output setting. Four curing lights delivered a single peak wavelength from 454 to 462 nm, and two (Bluephase Style and Valo Cordless) delivered multiple emission peaks (at 410 and 458 nm and 400, 450, and 460 nm, respectively). The irradiance and radiant exposure always decreased after 25 exposures by 2% to 8%, depending on the light unit; however, only ESPE Cordless, Valo Cordless, and Radii-Cal presented a statistical difference between the first and the last exposure. The tip diameter ranged from 6.77 mm to 9.40 mm. The Radii-Cal delivered the lowest radiant exposure and irradiance. This light was also unable to access all the teeth with the tip parallel to the occlusal surface of the tooth. Not all of the blue-emitting lights deliver the same emission spectra, and some curing lights delivered a lower irradiance (as much as 8% lower) after the 25th exposure.

  5. The propagation of a strong x-ray pulse followed by pulse slowdown and compression, amplified spontaneous emission and lasing without inversion

    Energy Technology Data Exchange (ETDEWEB)

    Sun Yuping; Liu Jicai; Gel' mukhanov, Faris, E-mail: jicai@theochem.kth.s [Department of Theoretical Chemistry, School of Biotechnology, Royal Institute of Technology, S-106 91 Stockholm (Sweden)

    2009-10-28

    We study self-seeded stimulated resonant x-ray Raman scattering and show a 20-fold compression of the strong XFEL pulse propagating through the resonant medium of atomic argon with the frequency (244.3 eV) tuned to the 2p{sub 3/2}-4s resonance. The strong x-ray pulse inverts the medium and produces an extensive ringing tail which widens the power spectrum. Newly created seed field triggers the Stokes channel 3s-2p{sub 3/2} of amplified spontaneous emission. The population inversions are quenched for longer propagation distances where lasing without inversion enhances the Stokes component. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. The group velocity is decreased up to 78% of the speed of light in vacuum. (fast track communication)

  6. The propagation of a strong x-ray pulse followed by pulse slowdown and compression, amplified spontaneous emission and lasing without inversion

    International Nuclear Information System (INIS)

    Sun Yuping; Liu Jicai; Gel'mukhanov, Faris

    2009-01-01

    We study self-seeded stimulated resonant x-ray Raman scattering and show a 20-fold compression of the strong XFEL pulse propagating through the resonant medium of atomic argon with the frequency (244.3 eV) tuned to the 2p 3/2 -4s resonance. The strong x-ray pulse inverts the medium and produces an extensive ringing tail which widens the power spectrum. Newly created seed field triggers the Stokes channel 3s-2p 3/2 of amplified spontaneous emission. The population inversions are quenched for longer propagation distances where lasing without inversion enhances the Stokes component. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. The group velocity is decreased up to 78% of the speed of light in vacuum. (fast track communication)

  7. Bright up-conversion white light emission from Er3+ doped lithium fluoro zinc borate glasses for photonic applications

    Science.gov (United States)

    Vijayalakshmi, L.; Naveen Kumar, K.; Rao, K. Srinivasa; Hwang, Pyung

    2018-03-01

    Various concentrations of Er3+ (0.3, 0.5, 1.0 and 1.5 mol %) doped lithium fluoro zinc borate glasses were synthesized by a traditional melt quenching method. XRD, FTIR and FESEM have been employed to analyze the structural, compositional and morphological analysis respectively. Judd-Ofelt theory has been employed to analyze the intensity parameters (Ωλ, λ = 2, 4 and 6) which can be used to estimate the radiative properties of fluorescent levels of Er3+. We have been observed a strong NIR emission peak at 1.53 μm (4I13/2 → 4I15/2) under the excitation of 980 nm from Er3+: LBZ glasses. Nevertheless, the NIR emission is remarkably enhanced by increasing the Er3+ ions concentration until the optimized concentration of 0.5 mol%. The lifetime of the excited level of 4I13/2 in the NIR emission transition is evaluated and it is found to be1.22 ms from the decay analysis of 0.5 mol% Er3+: LBZ glass. Apart from the NIR emission, a bright up-conversion green emission is observed at 544 nm (4S3/2 → 4I15/2) along with an intense red emission at 659 nm (4F9/2 → 4I15/2) and a weak blue emission (2H9/2 → 4I15/2) under the excitation of 980 nm. Up-conversion emission features were significantly enhanced with increasing the Er3+ concentration up to 1.0 mol%. The combination of the obtained up-conversion emission colors of green, red and blue could generate white light emission. The cool white-light emission from the optimized glass sample has been confirmed from the Commission International de I'Echairage (CIE) 1931 chromaticity diagram analysis and their correlated color temperature (CCT) values. Based on the NIR and up-conversion emission features, Er3+: LBZ glasses could be suggested as promising candidates for optical amplifiers, optical telecommunication windows and white light photonic applications.

  8. Light Emission and Energy Transfer in Nanoscale Semiconductor Photonic Devices

    National Research Council Canada - National Science Library

    Kolbas, Robert

    1997-01-01

    .... The proposed research impacts device development and system architectures by demonstrating light emitters for wavelength division multiplexing, three dimensional IOEC structures, broadly tunable...

  9. Platinum nanoparticles strongly associated with graphitic carbon nitride as efficient co-catalysts for photocatalytic hydrogen evolution under visible light.

    Science.gov (United States)

    Shiraishi, Yasuhiro; Kofuji, Yusuke; Kanazawa, Shunsuke; Sakamoto, Hirokatsu; Ichikawa, Satoshi; Tanaka, Shunsuke; Hirai, Takayuki

    2014-12-14

    Platinum (Pt) nanoparticles with C3N4) by reduction at 673 K behave as efficient co-catalysts for photocatalytic hydrogen evolution under visible light (λ >420 nm). This is achieved by strong Pt-support interaction due to the high temperature treatment, which facilitates efficient transfer of photoformed conduction band electrons on g-C3N4 to Pt particles.

  10. 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.

  11. Light-duty vehicle greenhouse gas emission standards and corporate average fuel economy standards : final rule

    Science.gov (United States)

    2010-05-07

    Final Rule to establish a National Program consisting of new standards for light-duty vehicles that will reduce greenhouse gas emissions and improve fuel economy. This joint : Final Rule is consistent with the National Fuel Efficiency Policy announce...

  12. A Versatile and Simple Approach to Generate Light Emission in Semiconductors Mediated by Electric Double Layers

    KAUST Repository

    Pu, Jiang

    2017-04-18

    The light-emitting device is the primary device for current light sources. In principle, conventional light-emitting devices need heterostructures and/or intentional carrier doping to form a p-n junction. This junction formation is, however, very difficult to achieve for most emerging semiconductors, and the fabrication of light-emitting devices is invariably a significant challenge. This study proposes a versatile and simple approach to realize light-emitting devices. This proposed device requires only a semiconducting film with two electrodes that are covered with an electrolyte. This unique structure achieves light emission at a voltage slightly larger than the bandgap energy of materials. This study applies this concept to emerging direct bandgap semiconductors, such as transition metal dichalcogenide monolayers and zinc oxide single crystals. These devices generate obvious light emission and provide sufficient evidence of the formation of a dynamic p-i-n junction or tunneling junction, presenting a versatile technique to develop optoelectronic devices.

  13. Janus magneto-electric nanosphere dimers exhibiting unidirectional visible light scattering and strong electromagnetic field enhancement.

    Science.gov (United States)

    Wang, Hao; Liu, Pu; Ke, Yanlin; Su, Yunkun; Zhang, Lei; Xu, Ningsheng; Deng, Shaozhi; Chen, Huanjun

    2015-01-27

    Steering incident light into specific directions at the nanoscale is very important for future nanophotonics applications of signal transmission and detection. A prerequisite for such a purpose is the development of nanostructures with high-efficiency unidirectional light scattering properties. Here, from both theoretical and experimental sides, we conceived and demonstrated the unidirectional visible light scattering behaviors of a heterostructure, Janus dimer composed of gold and silicon nanospheres. By carefully adjusting the sizes and spacings of the two nanospheres, the Janus dimer can support both electric and magnetic dipole modes with spectral overlaps and comparable strengths. The interference of these two modes gives rise to the narrow-band unidirectional scattering behaviors with enhanced forward scattering and suppressed backward scattering. The directionality can further be improved by arranging the dimers into one-dimensional chain structures. In addition, the dimers also show remarkable electromagnetic field enhancements. These results will be important not only for applications of light emitting devices, solar cells, optical filters, and various surface enhanced spectroscopies but also for furthering our understanding on the light-matter interactions at the nanoscale.

  14. Boosting light emission from Si-based thin film over Si and SiO(2) nanowires architecture.

    Science.gov (United States)

    Yu, Zhongwei; Qian, Shengyi; Yu, Linwei; Misra, Soumyadeep; Zhang, Pei; Wang, Junzhuan; Shi, Yi; Xu, Ling; Xu, Jun; Chen, Kunji; Roca i Cabarrocas, Pere

    2015-03-09

    Silicon (Si)-based light emitting thin film has been a key ingredient for all-Si-based optoelectronics. Besides material engineering, adopting a novel 3D photonic architecture represents an effective strategy to boost light excitation and extraction from Si-based thin film material. We here explore the use of a nanowires (NW) framework, grown via vapor-liquid-solid mode, to achieve strongly enhanced yellow-green luminescence from SiN(x)O(y)/NW core-shell structure, with an order of magnitude enhancement compared to co-deposited planar references. We found that choosing geometrically-identical but different NW cores (Si or SiO(2)) can lead to profound influence on the overall light emission performance. Combining parametric investigation and theoretical modeling, we have been able to evaluate the key contributions arising from different mechanisms that include near-field enhancement, 3D light trapping and enhanced light extraction. These new findings indicate a new and effective strategy for strong Si-based thin film light emitting source, while being generic enough to be applicable in a wide variety of other thin film materials.

  15. Strong Geometrical Effects in Submillimeter Selective Area Growth and Light Extraction of GaN Light Emitting Diodes on Sapphire

    Science.gov (United States)

    Tanaka, Atsunori; Chen, Renjie; Jungjohann, Katherine L.; Dayeh, Shadi A.

    2015-11-01

    Advanced semiconductor devices often utilize structural and geometrical effects to tailor their characteristics and improve their performance. We report here detailed understanding of such geometrical effects in the epitaxial selective area growth of GaN on sapphire substrates and utilize them to enhance light extraction from GaN light emitting diodes. Systematic size and spacing effects were performed side-by-side on a single 2” sapphire substrate to minimize experimental sampling errors for a set of 144 pattern arrays with circular mask opening windows in SiO2. We show that the mask opening diameter leads to as much as 4 times increase in the thickness of the grown layers for 20 μm spacings and that spacing effects can lead to as much as 3 times increase in thickness for a 350 μm dot diameter. We observed that the facet evolution in comparison with extracted Ga adatom diffusion lengths directly influences the vertical and lateral overgrowth rates and can be controlled with pattern geometry. Such control over the facet development led to 2.5 times stronger electroluminescence characteristics from well-faceted GaN/InGaN multiple quantum well LEDs compared to non-faceted structures.

  16. Computational strong-field quantum dynamics intense light-matter interactions

    CERN Document Server

    2017-01-01

    This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time-dependent Schrödinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi-configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.

  17. Computational strong-field quantum dynamics. Intense light-matter interactions

    Energy Technology Data Exchange (ETDEWEB)

    Bauer, Dieter (ed.) [Rostock Univ. (Germany). Inst. fuer Physik

    2017-09-01

    This graduate textbook introduces the computational techniques to study ultra-fast quantum dynamics of matter exposed to strong laser fields. Coverage includes methods to propagate wavefunctions according to the time dependent Schroedinger, Klein-Gordon or Dirac equation, the calculation of typical observables, time-dependent density functional theory, multi configurational time-dependent Hartree-Fock, time-dependent configuration interaction singles, the strong-field approximation, and the microscopic particle-in-cell approach.

  18. Double differential light charged particle emission cross sections for some structural fusion materials

    Directory of Open Access Journals (Sweden)

    Sarpün Ismail Hakki

    2017-01-01

    Full Text Available In fusion reactors, neutron induced radioactivity strongly depends on the irradiated material. So, a proper selection of structural materials will have been limited the radioactive inventory in a fusion reactor. First-wall and blanket components have high radioactivity concentration due to being the most flux-exposed structures. The main objective of fusion structural material research is the development and selection of materials for reactor components with good thermo-mechanical and physical properties, coupled with low-activation characteristics. Double differential light charged particle emission cross section, which is a fundamental data to determine nuclear heating and material damages in structural fusion material research, for some elements target nuclei have been calculated by the TALYS 1.8 nuclear reaction code at 14–15 MeV neutron incident energy and compared with available experimental data in EXFOR library. Direct, compound and pre-equilibrium reaction contribution have been theoretically calculated and dominant contribution have been determined for each emission of proton, deuteron and alpha particle.

  19. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  20. Measurement of fluorescence emission spectrum of few strongly driven atoms using an optical nanofiber.

    Science.gov (United States)

    Das, Manoj; Shirasaki, A; Nayak, K P; Morinaga, M; Le Kien, Fam; Hakuta, K

    2010-08-02

    We show that the fluorescence emission spectrum of few atoms can be measured by using an optical nanofiber combined with the optical heterodyne and photon correlation spectroscopy. The observed fluorescence spectrum of the atoms near the nanofiber shows negligible effects of the atom-surface interaction and agrees well with the Mollow triplet spectrum of free-space atoms at high excitation intensity.

  1. Photoelectric charging of dust particles: Effect of spontaneous and light induced field emission of electrons

    International Nuclear Information System (INIS)

    Sodha, M. S.; Dixit, A.

    2009-01-01

    The authors have analyzed the charging of dust particles in a plasma, taking into account the electron/ion currents to the particles, electron/ion generation and recombination, electric field emission, photoelectric emission and photoelectric field emission of electrons under the influence of light irradiation; the irradiance has been assumed to be at a level, which lets the particles retain the negative sign of the charge. Numerical results and discussion conclude the papers.

  2. Maatregelen ter vermindering van fijnstofemissie uit de pluimveehouderij; invloed lichtschema op fijnstof- en ammoniakemissie uit vleeskuikenstallen = Measures to reduce fine dust emissions from poultry housings; influence light schedules on dust and ammonia emission from broiler houses

    NARCIS (Netherlands)

    Harn, van J.; Mosquera Losada, J.; Aarnink, A.J.A.

    2009-01-01

    The influence of light schedules and light intensity on fine dust and ammonia emission from broiler houses were studied. No significant effects of light schedule and light intensity were found on fine dust and ammonia emission from broilers

  3. Field emission properties and strong localization effect in conduction mechanism of nanostructured perovskite LaNiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Kamble, Ramesh B., E-mail: rbk.physics@coep.ac.in [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India); Department of Physics, College of Engineering, Pune 411005, Maharashtra (India); Tanty, Narendra; Patra, Ananya; Prasad, V. [Department of Physics, Indian Institute of Science, Bangalore 560012, Karnataka (India)

    2016-08-22

    We report the potential field emission of highly conducting metallic perovskite lanthanum nickelate (LaNiO{sub 3}) from the nanostructured pyramidal and whisker shaped tips as electron emitters. Nano particles of lanthanum nickelate (LNO) were prepared by sol-gel route. Structural and morphological studies have been carried out. Field emission of LNO exhibited high emission current density, J = 3.37 mA/cm{sup 2} at a low threshold electric field, E{sub th} = 16.91 V/μm, obeying Fowler–Nordheim tunneling. The DC electrical resistivity exhibited upturn at 11.6 K indicating localization of electron at low temperature. Magnetoresistance measurement at different temperatures confirmed strong localization in nanostructured LNO obeying Anderson localization effect at low temperature.

  4. Yellow light emission from Ta2O5:Er, Eu, Ce thin films deposited using a simple co-sputtering method

    Directory of Open Access Journals (Sweden)

    K. Miura

    2015-01-01

    Full Text Available Erbium, europium, and cerium co-doped tantalum oxide (Ta2O5:Er, Eu, Ce thin films were prepared using a simple co-sputtering method, and yellow light emission was observed by the naked eye from a sample annealed at 900 °C for 20 min. The hexagonal Ta2O5 phase is very important, but the hexagonal CeTa7O19 phase should be avoided to obtain strong yellow light emission from Ta2O5:Er, Eu, Ce films. The co-sputtered films can be used as high-refractive-index and yellow-light-emitting materials of autocloned photonic crystals that can be applied to novel light-emission devices, and they will also be used as anti-reflection and down-conversion layers toward high-efficiency silicon solar cells.

  5. Silver Nanoshell Plasmonically Controlled Emission of Semiconductor Quantum Dots in the Strong Coupling Regime.

    Science.gov (United States)

    Zhou, Ning; Yuan, Meng; Gao, Yuhan; Li, Dongsheng; Yang, Deren

    2016-04-26

    Strong coupling between semiconductor excitons and localized surface plasmons (LSPs) giving rise to hybridized plexciton states in which energy is coherently and reversibly exchanged between the components is vital, especially in the area of quantum information processing from fundamental and practical points of view. Here, in photoluminescence spectra, rather than from common extinction or reflection measurements, we report on the direct observation of Rabi splitting of approximately 160 meV as an indication of strong coupling between excited states of CdSe/ZnS quantum dots (QDs) and LSP modes of silver nanoshells under nonresonant nanosecond pulsed laser excitation at room temperature. The strong coupling manifests itself as an anticrossing-like behavior of the two newly formed polaritons when tuning the silver nanoshell plasmon energies across the exciton line of the QDs. Further analysis substantiates the essentiality of high pump energy and collective strong coupling of many QDs with the radiative dipole mode of the metallic nanoparticles for the realization of strong coupling. Our finding opens up interesting directions for the investigation of strong coupling between LSPs and excitons from the perspective of radiative recombination under easily accessible experimental conditions.

  6. Light charged particle emission in heavy-ion reactions–What have ...

    Indian Academy of Sciences (India)

    Light charged particle emission in heavy-ion reactions – What have we learnt? S Kailas ... Keywords. Light charged particles; heavy-ion induced reactions; particle spectra and angular distributions; reaction mechanisms. ... S Kailas1. Nuclear Physics Division, Bhabha Atomic Research Centre, Mumbai 400 085, India ...

  7. The early-type strong emission-line supergiants of the Magellanic Clouds - A spectroscopic zoology

    Science.gov (United States)

    Shore, S. N.; Sanduleak, N.

    1984-01-01

    The results of a spectroscopic survey of 21 early-type extreme emission line supergiants of the Large and Small Magellanic Clouds using IUE and optical spectra are presented. The combined observations are discussed and the literature on each star in the sample is summarized. The classification procedures and the methods by which effective temperatures, bolometric magnitudes, and reddenings were assigned are discussed. The derived reddening values are given along with some results concerning anomalous reddening among the sample stars. The derived mass, luminosity, and radius for each star are presented, and the ultraviolet emission lines are described. Mass-loss rates are derived and discussed, and the implications of these observations for the evolution of the most massive stars in the Local Group are addressed.

  8. 'Beam-emission spectroscopy' diagnostics also measure edge fast-ion light

    International Nuclear Information System (INIS)

    Heidbrink, W W; Bortolon, A; McKee, G R; Smith, D R

    2011-01-01

    Beam-emission spectroscopy (BES) diagnostics normally detect fluctuations in the light emitted by an injected neutral beam. Under some circumstances, however, light from fast ions that charge exchange in the high neutral-density region at the edge of the plasma make appreciable contributions to the BES signals. This 'passive' fast-ion D α (FIDA) light appears in BES signals from both the DIII-D tokamak and the National Spherical Torus Experiment (NSTX). One type of passive FIDA light is associated with classical orbits that traverse the edge. Another type is caused by instabilities that expel fast ions from the core; this light can complicate measurement of the instability eigenfunction.

  9. Blackbody emission from light interacting with an effective moving dispersive medium.

    Science.gov (United States)

    Petev, M; Westerberg, N; Moss, D; Rubino, E; Rimoldi, C; Cacciatori, S L; Belgiorno, F; Faccio, D

    2013-07-26

    Intense laser pulses excite a nonlinear polarization response that may create an effective flowing medium and, under appropriate conditions, a blocking horizon for light. Here, we analyze in detail the interaction of light with such laser-induced flowing media, fully accounting for the medium dispersion properties. An analytical model based on a first Born approximation is found to be in excellent agreement with numerical simulations based on Maxwell's equations and shows that when a blocking horizon is formed, the stimulated medium scatters light with a blackbody emission spectrum. Based on these results, diamond is proposed as a promising candidate medium for future studies of Hawking emission from artificial, dispersive horizons.

  10. The effects of emission control strategies on light-absorbing carbon emissions from a modern heavy-duty diesel engine.

    Science.gov (United States)

    Robinson, Michael A; Olson, Michael R; Liu, Z Gerald; Schauer, James J

    2015-06-01

    Control of atmospheric black carbon (BC) and brown carbon (BrC) has been proposed as an important pathway to climate change mitigation, but sources of BC and BrC are still not well understood. In order to better identify the role of modern heavy-duty diesel engines on the production of BC and BrC, emissions from a heavy-duty diesel engine operating with different emission control strategies were examined using a source dilution sampling system. The effect of a diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) on light-absorbing carbon (LAC) was evaluated at three steady-state engine operation modes: idle, 50% speed and load, and 100% speed and load. LAC was measured with four different engine configurations: engine out, DOC out, DPF out, and engine out with an altered combustion calibration. BC and BrC emission rates were measured with the Aethalometer (AE-31). EC and BC emission rates normalized to the mass of CO₂emitted increased with increasing engine speed and load. Emission rates normalized to brake-specific work did not exhibit similar trends with speed and load, but rather the highest emission rate was measured at idle. EC and OC emissions were reduced by 99% when the DOC and DPF architecture was applied. The application of a DPF was equally effective at removing 99% of the BC fraction of PM, proving to be an important control strategy for both LAC and PM. BC emissions were unexpectedly increased across the DOC, seemingly due to a change aerosol optical properties. Removal of exhaust gas recirculation (EGR) flow due to simulated EGR cooler failure caused a large increase in OC and BrC emission rates at idle, but had limited influence during high load operation. LAC emissions proved to be sensitive to the same control strategies effective at controlling the total mass of diesel PM. In the context of black carbon emissions, very small emission rates of brown carbon were measured over a range of control technologies and engine operating

  11. Comparison of real-world and certification emission rates for light duty gasoline vehicles.

    Science.gov (United States)

    Khan, Tanzila; Frey, H Christopher

    2018-05-01

    U.S. light duty vehicles are subject to the U.S. Environmental Protection Agency (EPA) emission standards. Emission compliance is determined by certification testing of selected emissions from representative vehicles on standard driving cycles using chassis dynamometers. Test results are also used in many emission inventories. The dynamometer based emission rates are adjusted to provide the certification levels (CL), which must be lower than the standards for compliance. Although standard driving cycles are based on specific observations of real-world driving, they are not necessarily real-world representative. A systematic comparison of the real-world emission rates of U.S. light duty gasoline vehicles (LDGVs) versus CL, and emission standards has not been previously reported. The purpose of this work is to compare regulatory limits (both CLs and emission standards) and the real-world emissions of LDGVs. The sensitivity of the comparisons to cold start emission was assessed. Portable Emission Measurement Systems (PEMS) were used to measure hot stabilized exhaust emissions of 122 LDGVs on a specified 110 mile test route. Cold start emissions were measured with PEMS for a selected vehicle sample of 32 vehicles. Emissions were measured for carbon dioxide (CO 2 ), carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NO x ). For each vehicle, a Vehicle Specific Power (VSP) modal emission rate model was developed. The VSP modal rates were weighted by the standard driving cycles and real-world driving cycles to estimate the respective cycle average emission rates (CAERs). Measured vehicles were matched with certification test vehicles for comparison. For systematic trends in comparison, vehicles were classified into four groups based on the Tier 1 and Tier 2 emission regulation, and the vehicle type such as passenger car and passenger truck. Depending on the cycle-pollutant and the vehicle groups, hot stabilized CAERs are on average either statistically

  12. Organic light emission structures — XXI century technologies

    Directory of Open Access Journals (Sweden)

    Sorokin V. M.

    2009-02-01

    Full Text Available The given review allows to believe, that the decision of a complex technological, materialstechnological, technical problems at creation modern OLED- and PLED-devices in nearest 5—10 years will result in creation of devices with power efficiency more than 100 lm/W and service life till 100 000 hours. The realization of such parameters will allow to expand area of application of the considered systems and to create in the future unique flat powereffective organic lighting systems of new generation — light sources XXI of century.

  13. Particulate emission rates from light-duty vehicles in the South Coast Air Quality Management District

    International Nuclear Information System (INIS)

    Durbin, T.D.; Norbeck, J.M.; Smith, M.R.; Truex, T.J.

    1999-01-01

    This paper presents the results of a particulate emission rate study conducted on 129 light-duty gasoline and 19 light-duty diesel vehicles for the Coordinating Research Council's (CRC's) Project E-24-2. Total particulate emission rates for newer gasoline vehicles were low with modest increases with vehicle age and older technology. Average FTP particulate emission rates as a function of model year for gasoline vehicles were found to be 2.5 mg/mi for 1991 and newer models, 14.4 mg/mi for 1986--1990 models, 49.0 mg/mi for 1981--1985 models, and 33.8 mg/mi for 1980 and older models. High gaseous emitters were found to have approximately 5--10 times the particulate emission rates of normal emitters. The diesel vehicles had an average particulate emission rate of 561 mg/mi. It should be noted that the light-duty diesel vehicles were predominantly older, pre-1985 vehicles; the 1985 and newer diesel vehicles had substantially lower particulate emissions, i.e., less than 100 mg/mi. Emission inventory estimates in the South Coast Air Basin based on the fleet emission rates were higher than those obtained using the default values in EMFAC7G, due primarily to the contribution of high emitters

  14. Can we bet on negative emissions to achieve the 2°C target even under strong carbon cycle feedbacks?

    Science.gov (United States)

    Tanaka, K.; Yamagata, Y.; Yokohata, T.; Emori, S.; Hanaoka, T.

    2015-12-01

    Negative emission technologies such as Bioenergy with Carbon dioxide Capture and Storage (BioCCS) play an ever more crucial role in meeting the 2°C stabilization target. However, such technologies are currently at their infancy and their future penetrations may fall short of the scale required to stabilize the warming. Furthermore, the overshoot in the mid-century prior to a full realization of negative emissions would give rise to a risk because such a temporal but excessive warming above 2°C might amplify itself by strengthening climate-carbon cycle feedbacks. It has not been extensively assessed yet how carbon cycle feedbacks might play out during the overshoot in the context of negative emissions. This study explores how 2°C stabilization pathways, in particular those which undergo overshoot, can be influenced by carbon cycle feedbacks and asks their climatic and economic consequences. We compute 2°C stabilization emissions scenarios under a cost-effectiveness principle, in which the total abatement costs are minimized such that the global warming is capped at 2°C. We employ a reduced-complexity model, the Aggregated Carbon Cycle, Atmospheric Chemistry, and Climate model (ACC2), which comprises a box model of the global carbon cycle, simple parameterizations of the atmospheric chemistry, and a land-ocean energy balance model. The total abatement costs are estimated from the marginal abatement cost functions for CO2, CH4, N2O, and BC.Our preliminary results show that, if carbon cycle feedbacks turn out to be stronger than what is known today, it would incur substantial abatement costs to keep up with the 2°C stabilization goal. Our results also suggest that it would be less expensive in the long run to plan for a 2°C stabilization pathway by considering strong carbon cycle feedbacks because it would cost more if we correct the emission pathway in the mid-century to adjust for unexpectedly large carbon cycle feedbacks during overshoot. Furthermore, our

  15. Spatial Evolution of a Strong Field of Few-cycle Light Beam in Dielectric Media with Induced Plasma Nonlinearity

    International Nuclear Information System (INIS)

    Stumpf, S A; Korolev, A A; Kozlov, S A

    2013-01-01

    The paper reports results of computer simulation of strong light beam propagation in dielectric media in case of plasma generation. We investigate an extra-broadening of radiation spectrum to a 'violet' wing of visible range. We show that the resulting pulse spectrum is represented by sequence of well-separated maximums, broadening as propagation distance increases. Experimental data are compared with simulation results, showing a good mutual correspondence of spectral representations

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

    Science.gov (United States)

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

    2018-01-01

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

  17. Charge transport and light emission in bilayer organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Li Weicong; Kwok, H.L., E-mail: hlkwok@ece.uvic.ca

    2012-02-29

    Recently there has been some major interest in the charge transport and light emission properties of organic field-effect transistors (OFETs). Different device structures have been proposed and they can be divided into two broad categories consisting of either a single layer or a bilayer. In the case of the single-layer OFETs, efficient light emission has not been observed while the performance of the bilayer OFETs appear to be more promising (for instance: recent work on a bilayer OFET has shown distinct ambipolar characteristics as well as limited light emission). In this work, we examined the electroluminescence intensities of bilayer OFETs reported in the open literature and attempted to identify the transport and recombination mechanisms. As observed, light emission in these devices appeared to be linked to a narrow region at the interface acting as a light-emitting source. To understand the recombination mechanisms, we computed the spatial charge distributions under various biasing conditions and correlated the results to the reported electroluminescence intensity data. Our overall results re-affirmed the significance of the light-emitting interface layer and the fact that device operation critically depended on the alignment of the energy levels at the respective interface. - Highlights: Black-Right-Pointing-Pointer Data taken from a reported bilayer OFET had been analyzed. Black-Right-Pointing-Pointer Transport and light emission mechanisms were used explain the device operation. Black-Right-Pointing-Pointer Light emission was found to depend on the charge distribution under bias. Black-Right-Pointing-Pointer We highlighted the opportunities to improve the device performance.

  18. Light-emission from in-situ grown organic nanostructures

    DEFF Research Database (Denmark)

    Oliveira Hansen, Roana Melina de; Kjelstrup-Hansen, Jakob; Rubahn, Horst-Günter

    2011-01-01

    purposes, the high quantum yield and the easy tunability of the color by changing the molecular building blocks are especially important. The application of such nanostructures as electrically driven light-emitters requires integration with suitable metal electrodes for efficient carrier injection. Here...

  19. Strong light-extraction enhancement in GaInN light-emitting diodes patterned with TiO2 micro-pillars with tapered sidewalls

    Science.gov (United States)

    Ma, Ming; Cho, Jaehee; Fred Schubert, E.; Park, Yongjo; Bum Kim, Gi; Sone, Cheolsoo

    2012-10-01

    An effective method to enhance the light extraction for GaInN light-emitting diodes (LEDs) is reported. The method employs TiO2 micro-pillars with tapered sidewalls, which are refractive-index-matched to the underlying GaN. The tapered micro-pillars are fabricated by using reflowed photoresist as mask during CHF3-based dry etch, with O2 added in order to precisely control the taper angle. LEDs patterned with TiO2 micro-pillars with tapered sidewalls show a 100% enhancement in light-output power over planar reference LEDs. The measured results are in good agreement with ray-tracing simulations, showing strong potential of optical surfaces that are controlled in terms of refractive index and lateral structure.

  20. STRONG RESPONSE OF THE VERY BROAD Hβ EMISSION LINE IN THE LUMINOUS RADIO-QUIET QUASAR PG 1416-129

    International Nuclear Information System (INIS)

    Wang, J.; Li, Y.

    2011-01-01

    We report new spectroscopic observations performed in 2010 and 2011 for the luminous radio-quiet quasar PG 1416-129. Our new spectra with high quality cover both Hβ and Hα regions, and show negligible line profile variation within a timescale of one year. The two spectra allow us to study the variability of the Balmer line profile by comparing the spectra with previous ones taken at 10 and 20 years ago. By decomposing the broad Balmer emission lines into two Gaussian profiles, our spectral analysis suggests a strong response to the continuum level for the very broad component, and significant variations in both bulk blueshift velocity/FWHM and flux for the broad component. The new observations additionally indicate flat Balmer decrements (i.e., too strongemission) at the line wings, which is hard to reproduce using recent optically thin models. With these observations we argue that a separate inner optically thin emission-line region might not be necessary in the object to reproduce the observed line profiles.

  1. Hybrid Light-Emitting Diode Enhanced With Emissive Nanocrystals

    DEFF Research Database (Denmark)

    Kopylov, Oleksii

    of the hybrid diode fabrication including process techniques for GaN LED and incorporation of the nanocrystals are presented with the emphasis on the differences with standard LED processing. Results and analysis of optical and electrical characterization including photoluminescence (PL), micro-PL, time......This thesis investigates a new type of white light emitting hybrid diode, composed of a light emitting GaN/InGaN LED and a layer of semiconductor nanocrystals for color conversion. Unlike standard white LEDs, the device is configured to achieve high color conversion efficiency via non......-radiative energy transfer from the primary LED to the nanocrystals. LED structures with sub-10 nm separation the between quantum well and the surface and patterned standard bright LEDs are considered for the hybrid devices, which require close proximity of the nanocrystals to the quantum well. The development...

  2. Elastic removal self-shielding factors for light and medium nuclides with strong-resonance scattering

    International Nuclear Information System (INIS)

    Nakagawa, Masayuki; Ishiguro, Yukio; Tokuno, Yukio.

    1978-01-01

    The self-shielding factors for elastic removal cross sections of light and medium weight nuclides were calculated for the parameter, σ 0 within the conventional concept of the group constant sets. The numerical study were performed for obtaining a simple and accurate method. The present results were compared with the exact values and the conventional ones, and shown to be remarkably improved. It became apparent that the anisotropy of the elastic scattering did not affect to the self-shielding factors though it did to the infinite dilution cross sections. With use of the present revised set, the neutron flux were calculated in an iron medium and in a prototype FBR and compared with those by the fine spectrum calculations and the conventional set. The present set showed the considerable improvement in the vicinity of the large resonance regions of sodium, iron and oxygen. (auth.)

  3. Studies of light emission by continuously sensitive avalanche chambers

    International Nuclear Information System (INIS)

    Charpak, G.; Dominik, W.; Fabre, J.P.; Gaudaen, J.; Sauli, F.; Suzuki, M.

    1988-01-01

    The optimal conditions for the optical recording of images of electron avalanches between parallel meshes have been studied. The emission spectra of gas mixtures have been investigated, where triethylamine (TEA), tetrakis(dimethylamine)ethylene (TMAE), and nitrogen, are used as the photon-emitting agents. For a given charge gain, the photon intensity decreases with electric field. This favours amplification between parallel meshes instead of wires. The use of intensified CCD cameras permits the recording of the local energy loss along the tracks. (orig.)

  4. Description of light charged particle emission in ternary fission

    International Nuclear Information System (INIS)

    Andreev, A. V.; Adamian, G. G.; Antonenko, N. V.; Kuklin, S. N.; Scheid, W.

    2010-01-01

    We consider the motion of three fragments starting from the scission point of ternary system. In the alpha-accompanied ternary fission the initial conditions are not the free parameters and determined by minimization of potential energy at scission point. In the trajectory calculations the angular distribution and mean value of the kinetic energy of the alpha-particles are well described in the spontaneous ternary fission of 252 Cf. In the Be- and C-accompanied ternary fission we found that the emission of the third particle occurs from one of the heavy fragments after their separation. (authors)

  5. Quantum Femtosecond Magnetism: Phase Transition in Step with Light in a Strongly Correlated Manganese Oxide

    Science.gov (United States)

    Wang, Jigang

    2014-03-01

    Research of non-equilibrium phase transitions of strongly correlated electrons is built around addressing an outstanding challenge: how to achieve ultrafast manipulation of competing magnetic/electronic phases and reveal thermodynamically hidden orders at highly non-thermal, femtosecond timescales? Recently we reveal a new paradigm called quantum femtosecond magnetism-photoinduced femtosecond magnetic phase transitions driven by quantum spin flip fluctuations correlated with laser-excited inter-atomic coherent bonding. We demonstrate an antiferromagnetic (AFM) to ferromagnetic (FM) switching during about 100 fs laser pulses in a colossal magneto-resistive manganese oxide. Our results show a huge photoinduced femtosecond spin generation, measured by magnetic circular dichroism, with photo-excitation threshold behavior absent in the picosecond dynamics. This reveals an initial quantum coherent regime of magnetism, while the optical polarization/coherence still interacts with the spins to initiate local FM correlations that compete with the surrounding AFM matrix. Our results thus provide a framework that explores quantum non-equilibrium kinetics to drive phase transitions between exotic ground states in strongly correlated elecrons, and raise fundamental questions regarding some accepted rules, such as free energy and adiabatic potential surface. This work is in collaboration with Tianqi Li, Aaron Patz, Leonidas Mouchliadis, Jiaqiang Yan, Thomas A. Lograsso, Ilias E. Perakis. This work was supported by the National Science Foundation (contract no. DMR-1055352). Material synthesis at the Ames Laboratory was supported by the US Department of Energy-Basic Energy Sciences (contract no. DE-AC02-7CH11358).

  6. How to prevent greenhouse gas emissions in electrical installations: lighting energy savings and solar energy approaches

    International Nuclear Information System (INIS)

    Yavuz, C.; Aksoy, C.

    2012-01-01

    Day by day greenhouse gas emissions increase dramatically. A passive adaptive method of lighting energy savings, daylight responsive systems are considered one of the best solutions for energy efficiency, saving and prevent CO 2 emissions. Results of an annual experiment which was held in Sakarya University proves the necessity of daylight responsive systems with a 41% energy saving and 942.5 kg of prevented CO 2 emissions Thinking this prevention is realized just only in a 36 m 2 room with the use of 8 luminaries spreading such systems to nationwide, a major amount of greenhouse gas emissions would be prohibited. On the other hand energy saving is not the only way to reduce CO 2 emissions. Again in Sakarya University a project has started to investigate the possibility of illumination of a complete building by using solar energy. This paper evaluates these mentioned systems both in energy efficiency, greenhouse gas emissions prevention and economic point of views. (author)

  7. White light emission from fluorescent SiC with porous surface

    DEFF Research Database (Denmark)

    Lu, Weifang; Ou, Yiyu; Fiordaliso, Elisabetta Maria

    2017-01-01

    the bulk fuorescent SiC layer. A high color rendering index of 81.1 has been achieved. Photoluminescence spectra in porous layers fabricated in both commercial n-type and lab grown N-B co-doped 6H-SiC show two emission peaks centered approximately at 460nm and 530nm. Such bluegreen emission phenomenon can......, the photoluminescence intensity from the porous layer was signifcant enhanced by a factor of more than 12. Using a porous layer of moderate thickness (~10µm), high-quality white light emission was realized by combining the independent emissions of blue-green emission from the porous layer and yellow emission from...

  8. The emission function of ground-based light sources: State of the art and research challenges

    Science.gov (United States)

    Solano Lamphar, Héctor Antonio

    2018-05-01

    To understand the night sky radiance generated by the light emissions of urbanised areas, different researchers are currently proposing various theoretical approaches. The distribution of the radiant intensity as a function of the zenith angle is one of the most unknown properties on modelling skyglow. This is due to the collective effects of the artificial radiation emitted from the ground-based light sources. The emission function is a key property in characterising the sky brightness under arbitrary conditions, therefore it is required by modellers, environmental engineers, urban planners, light pollution researchers, and experimentalists who study the diffuse light of the night sky. As a matter of course, the emission function considers the public lighting system, which is in fact the main generator of the skyglow. Still, another class of light-emitting devices are gaining importance since their overuse and the urban sprawl of recent years. This paper will address the importance of the emission function in modelling skyglow and the factors involved in its characterization. On this subject, the author's intention is to organise, integrate, and evaluate previously published research in order to state the progress of current research toward clarifying this topic.

  9. Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission.

    Science.gov (United States)

    Ondič, L; Varga, M; Pelant, I; Valenta, J; Kromka, A; Elliman, R G

    2017-07-18

    Light extraction from a thin planar layer can be increased by introducing a two-dimensional periodic pattern on its surface. This structure, the so-called photonic crystal (PhC) slab, then not only enhances the extraction efficiency of light but can direct the extracted emission into desired angles. Careful design of the structures is important in order to have a spectral overlap of the emission with extraction (leaky) modes. We show that by fabricating PhC slabs with optimized dimensions from silicon nanocrystals (SiNCs) active layers, the extraction efficiency of vertical light emission from SiNCs at a particular wavelength can be enhanced ∼ 11 times compared to that of uncorrugated SiNCs-rich layer. More importantly, increased light emission can be obtained in a broad spectral range and, simultaneously, the extracted light can stay confined within relatively narrow angle around the normal to the sample plane. We demonstrate experimentally and theoretically that the physical origin of the enhancement is such that light originating from SiNCs first couples to leaky modes of the PhCs and is then efficiently extracted into the surrounding.

  10. Faint Object Spectrograph Spectra of the UV Emission Lines in NGC 5558: Detection of Strong Narrow Components

    Science.gov (United States)

    Crenshaw, D. Michael; Boggess, Albert; Wu, Chi-Chao

    1993-01-01

    Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 were obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope on 1992 July 5, when the UV continuum and broad emission lines were at their lowest ever observed level. The high resolution of the spectra, relative to previous UV observations, and the low state of NGC 5548 allow the detection and accurate measurement of strong narrow components of the emission lines of Ly alpha, C IV 1549, and C III 1909. Isolation of the UV narrow components enables a detailed comparison of narrow-line region (NLR) properties in Seyfert 1 and 2 galaxies, and removal of their contribution is important for studies of the broad-line region (BLR). Relative to the other narrow lines, C IV 1549 is much stronger in NGC 5548 than in Seyfert 2 galaxies, and Mg II 2798 is very weak or absent.

  11. Helical light emission from plasmonic vortices via magnetic tapered tip

    Science.gov (United States)

    Maccaferri, N.; Gorodetski, Y.; Garoli, D.

    2018-01-01

    We investigate an architecture where a plasmonic vortex excited in a gold surface propagates on an adiabatically tapered magnetic tip and detaches to the far-field while carrying a well-defined optical angular momentum. We analyze the out-coming light and show that, despite generally high losses of flat magnetic surface, our 3D structure exhibits high energy throughput. Moreover, we show that once a magneto-optical activity is activated inside the magnetic tip a modulation of the total power transmittance is possible.

  12. Inelastic light scattering to probe strongly correlated bosons in optical lattices

    International Nuclear Information System (INIS)

    Fort, Chiara; Fabbri, Nicole; Fallani, Leonardo; Clement, David; Inguscio, Massimo

    2011-01-01

    We have used inelastic light scattering to study correlated phases of an array of one-dimensional interacting Bose gases. In the linear response regime, the observed spectra are proportional to the dynamic structure factor. In particular we have investigated the superfluid to Mott insulator crossover loading the one-dimensional gases in an optical lattice and monitoring the appearance of an energy gap due to finite particle-hole excitation energy. We attribute the low frequency side of the spectra to the presence of some superfluid and normal phase fraction between the Mott insulator regions with different fillings produced in the inhomogeneous systems. In the Mott phase we also investigated excitations to higher excited bands of the optical lattice, the spectra obtained in this case being connected to the single particle spectral function. In one-dimensional systems the effect of thermal fluctuations and interactions is enhanced by the reduced dimensionality showing up in the dynamic structure factor. We measured the dynamic structure factor of an array of one-dimensional bosonic gases pointing out the effect of temperature-induced phase fluctuations in reducing the coherence length of the system.

  13. Strongly emissive perovskite nanocrystal inks for high-voltage solar cells

    Science.gov (United States)

    Akkerman, Quinten A.; Gandini, Marina; di Stasio, Francesco; Rastogi, Prachi; Palazon, Francisco; Bertoni, Giovanni; Ball, James M.; Prato, Mirko; Petrozza, Annamaria; Manna, Liberato

    2016-12-01

    Lead halide perovskite semiconductors have recently gained wide interest following their successful embodiment in solid-state photovoltaic devices with impressive power-conversion efficiencies, while offering a relatively simple and low-cost processability. Although the primary optoelectronic properties of these materials have already met the requirement for high-efficiency optoelectronic technologies, industrial scale-up requires more robust processing methods, as well as solvents that are less toxic than the ones that have been commonly used so successfully on the lab-scale. Here we report a fast, room-temperature synthesis of inks based on CsPbBr3 perovskite nanocrystals using short, low-boiling-point ligands and environmentally friendly solvents. Requiring no lengthy post-synthesis treatments, the inks are directly used to fabricate films of high optoelectronic quality, exhibiting photoluminescence quantum yields higher than 30% and an amplified spontaneous emission threshold as low as 1.5 μJ cm-2. Finally, we demonstrate the fabrication of perovskite nanocrystal-based solar cells, with open-circuit voltages as high as 1.5 V.

  14. Comparisons of MOVES Light-duty Gasoline NOx Emission Rates with Real-world Measurements

    Science.gov (United States)

    Choi, D.; Sonntag, D.; Warila, J.

    2017-12-01

    Recent studies have shown differences between air quality model estimates and monitored values for nitrogen oxides. Several studies have suggested that the discrepancy between monitored and modeled values is due to an overestimation of NOx from mobile sources in EPA's emission inventory, particularly for light-duty gasoline vehicles. EPA's MOtor Vehicle Emission Simulator (MOVES) is an emission modeling system that estimates emissions for cars, trucks and other mobile sources at the national, county, and project level for criteria pollutants, greenhouse gases, and air toxics. Studies that directly measure vehicle emissions provide useful data for evaluating MOVES when the measurement conditions are properly accounted for in modeling. In this presentation, we show comparisons of MOVES2014 to thousands of real-world NOx emissions measurements from individual light-duty gasoline vehicles. The comparison studies include in-use vehicle emissions tests conducted on chassis dynamometer tests in support of Denver, Colorado's Vehicle Inspection & Maintenance Program and remote sensing data collected using road-side instruments in multiple locations and calendar years in the United States. In addition, we conduct comparisons of MOVES predictions to fleet-wide emissions measured from tunnels. We also present details on the methodology used to conduct the MOVES model runs in comparing to the independent data.

  15. Chamber study of PCB emissions from caulking materials and light ballasts.

    Science.gov (United States)

    Liu, Xiaoyu; Guo, Zhishi; Krebs, Kenneth A; Stinson, Rayford A; Nardin, Joshua A; Pope, Robert H; Roache, Nancy F

    2015-10-01

    The emissions of polychlorinated biphenyl (PCB) congeners from thirteen caulk samples were tested in a micro-chamber system. Twelve samples were from PCB-contaminated buildings and one was prepared in the laboratory. Nineteen light ballasts collected from buildings that represent 13 different models from five manufacturers were tested in 53-L environmental chambers. The rates of PCB congener emissions from caulking materials and light ballasts were determined. Several factors that may have affected the emission rates were evaluated. The experimentally determined emission factors showed that, for a given PCB congener, there is a linear correlation between the emission factor and the concentration of the PCB congener in the source. Furthermore, the test results showed that an excellent log-linear correlation exists between the normalized emission factor and the vapor pressure (coefficient of determination, r(2)⩾0.8846). The PCB congener emissions from ballasts at or near room temperature were relatively low with or without electrical load. However, the PCB congener emission rates increased significantly as the temperature increased. The results of this research provide new data and models for ranking the primary sources of PCBs and supports the development and refinement of exposure assessment models for PCBs. Published by Elsevier Ltd.

  16. Visualization of Nano-Plasmonic Coupling to Molecular Orbital in Light Emission Induced by Tunneling Electrons.

    Science.gov (United States)

    Yu, Arthur; Li, Shaowei; Wang, Hui; Chen, Siyu; Wu, Ruqian; Ho, Wilson

    2018-04-16

    The coupling between localized plasmon and molecular orbital in the light emission from a metallic nanocavity has been directly detected and imaged with sub-0.1 nm resolution. The light emission intensity was enhanced when the energy difference between the tunneling electrons and the lowest unoccupied molecular orbital (LUMO) of an azulene molecule matches the energy of a plasmon mode of the nanocavity defined by the Ag-tip and Ag (110) substrate of a scanning tunneling microscope (STM). The spatially resolved image of the light emission intensity matches the spatial distribution of the LUMO obtained by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. Our results highlight the near-field coupling of a molecular orbital to the radiative decay of a plasmonic excitation in a confined nanoscale junction.

  17. Angle-dependent light emission from aligned multiwalled carbon nanotubes under CO2 laser irradiation

    International Nuclear Information System (INIS)

    Zhang, Y; Gong, T; Liu, W J; Wei, J Q; Zhang, X F; Wang, K L; Zhong, M L; Wu, D H

    2007-01-01

    This paper reports the light emission from aligned multiwalled carbon nanotubes (MWNTs) under continuous wave CO 2 laser (λ = 10.6 μm) irradiation. Results indicate that the light emission is dependent on the angle θ between the laser incident direction and the nanotube axis. The relative intensity of the light emission at certain wavelengths shows a Lorentzian feature when θ varies from 0 0 to 90 0 . The Lorentzian fitting curve displays a distinct tendency between shorter (λ 700 nm). A minimum intensity was observed at θ m close to 67 0 under shorter wavelength, whereas a maximum intensity was shown at θ m of about 60 0 at longer wavelength. These results show the anisotropic property of aligned MWNTs

  18. Color stable white phosphorescent organic light emitting diodes with red emissive electron transport layer

    Energy Technology Data Exchange (ETDEWEB)

    Wook Kim, Jin; Yoo, Seung Il; Sung Kang, Jin [Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Eun Lee, Song; Kwan Kim, Young [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Hwa Yu, Hyeong; Turak, Ayse [Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada); Young Kim, Woo, E-mail: wykim@hoseo.edu [Department of Green Energy & Semiconductor Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Department of Engineering Physics, McMaster University, Hamilton, Ontario L8S 4L7 (Canada)

    2015-06-28

    We analyzed the performance of multi-emissive white phosphorescent organic light-emitting diodes (PHOLEDs) in relation to various red emitting sites of hole and electron transport layers (HTL and ETL). The shift of the recombination zone producing stable white emission in PHOLEDs was utilized as luminance was increased with red emission in its electron transport layer. Multi-emissive white PHOLEDs including the red light emitting electron transport layer yielded maximum external quantum efficiency of 17.4% with CIE color coordinates (−0.030, +0.001) shifting only from 1000 to 10 000 cd/m{sup 2}. Additionally, we observed a reduction of energy loss in the white PHOLED via Ir(piq){sub 3} as phosphorescent red dopant in electron transport layer.

  19. Studies on the independence of the strong interactions on the flavor quantum numbers with bottom, charm, strange, and light quarks

    International Nuclear Information System (INIS)

    Biebel, O.

    1993-11-01

    A study of possible flavour dependence of the strong interaction is presented using data collected with the OPAL detector at the e + e - collider LEP. Four subsamples of events, highly enriched in bottom, charm, strange and light quarks are obtained from high momentum electrons and muons, D *± mesons, K s 0 mesons, and highly energetic stable charged particles, respectively. From the jet production rates of each of these four samples a strong coupling constant α s f for the dominant quark flavour is derived. The ratios of α s for a specific quark flavour f and its complementary flavours are determined to be α s b /α s udsc =1.017±0.036, α s c /α s udsb =0.918±0.115, α s s /α s udcb =1.158±0.164, α s uds /α s cb =1.038 ± 0.221, where the errors are combinations of statistical and systematic uncertainties. In combining the relevant data samples, a systematic study of possible dependence of the strong interaction on quark mass, weak isospin, and generation is performed. No evidence for any such dependence of the strong coupling constant α s is observed. Finally all samples are combined to determine the strong coupling constant of each flavour individually. Again the results are well consistent with the flavour independence of QCD. (orig.)

  20. Comparative studies of density-functional approximations for light atoms in strong magnetic fields

    Science.gov (United States)

    Zhu, Wuming; Zhang, Liang; Trickey, S. B.

    2014-08-01

    For a wide range of magnetic fields, 0≤B≤2000 a.u., we present a systematic comparative study of the performance of different types of density-functional approximations in light atoms (2≤Z≤6). Local, generalized-gradient approximation (GGA; semilocal), and meta-GGA ground-state exchange-correlation (xc) functionals are compared on an equal footing with exact-exchange, Hartree-Fock (HF), and current-density-functional-theory (CDFT) approximations. Comparison also is made with published quantum Monte Carlo data. Though all approximations give qualitatively reasonable results, the exchange energies from local and GGA functionals are too negative for large B. Results from the Perdew-Burke-Ernzerhof ground-state GGA and Tao-Perdew-Staroverov-Scuseria (TPSS) ground-state meta-GGA functionals are very close. Because of confinement, self-interaction error in such functionals is more severe at large B than at B =0, hence self-interaction correction is crucial. Exact exchange combined with the TPSS correlation functional results in a self-interaction-free (xc) functional, from which we obtain atomic energies of comparable accuracy to those from correlated wave-function methods. Specifically for the B and C atoms, we provide beyond-HF energies in a wide range of B fields. Fully self-consistent CDFT calculations were done with the Vignale-Rasolt-Geldart (VRG) functional in conjunction with the PW92 xc functional. Current effects turn out to be small, and the vorticity variable in the VRG functional diverges in some low-density regions. This part of the study suggests that nonlocal, self-interaction-free functionals may be better than local approximations as a starting point for CDFT functional construction and that some basic variable other than the vorticity could be helpful in making CDFT calculations practical.

  1. Emission of high-energy, light particles from intermediate-energy heavy-ion reactions

    International Nuclear Information System (INIS)

    Ball, J.B.; Auble, R.L.

    1982-01-01

    One of the early surprises in examining reaction products from heavy ion reactions at 10 MeV/nucleon and above was the large yield of light particles emitted and the high energies to which the spectra of these particles extended. The interpretation of the origin of the high energy light ions has evolved from a picture of projectile excitation and subsequent evaporation to one of pre-equilibrium (or nonequilibrium) emission. The time scale for particle emission has thus moved from one that occurs following the initial collision to one that occurs at the very early stages of the collision. Research at ORNL on this phenomenon is reviewed

  2. Visible Light Emission from Atomic Scale Patterns Fabricated by the Scanning Tunneling Microscope

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Stokbro, Kurt

    1999-01-01

    Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel...... mechanism involving optical transitions between a tip state and localized states on the sample surface. The wavelength of the photons can be changed by the bias voltage of the STM. The spatial resolution of the photon maps is as good as that of STM topographic images and the photons are emitted from...

  3. The contribution of Diamond Light Source to the study of strongly correlated electron systems and complex magnetic structures.

    Science.gov (United States)

    Radaelli, P G; Dhesi, S S

    2015-03-06

    We review some of the significant contributions to the field of strongly correlated materials and complex magnets, arising from experiments performed at the Diamond Light Source (Harwell Science and Innovation Campus, Didcot, UK) during the first few years of operation (2007-2014). We provide a comprehensive overview of Diamond research on topological insulators, multiferroics, complex oxides and magnetic nanostructures. Several experiments on ultrafast dynamics, magnetic imaging, photoemission electron microscopy, soft X-ray holography and resonant magnetic hard and soft X-ray scattering are described. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  4. Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends Data

    Science.gov (United States)

    The Light-Duty Automotive Technology, Carbon Dioxide Emissions, and Fuel Economy Trends report is the authoritative reference for carbon dioxide (CO2) emissions, fuel economy, and powertrain technology trends for new personal vehicles in the United States. The ??Trends?? report has been published annually since 1975 and covers all passenger cars, sport utility vehicles, minivans, and all but the largest pickup trucks and vans. This report does not provide formal compliance values for EPA CO2 emissions standards and NHTSA CAFE standards. The downloadable data are available in PDF or spreadsheet (XLS) formats.

  5. Sharply directed emission in microcavity organic light-emitting diodes with a cholesteric liquid crystal film

    Science.gov (United States)

    Jeong, Soon Moon; Takanishi, Yoichi; Ishikawa, Ken; Nishimura, Suzushi; Suzaki, Goroh; Takezoe, Hideo

    2007-05-01

    A flexible microcavity organic light-emitting diode (OLED) was fabricated and the emitting characteristics were examined. A pair of right- and left-handed cholesteric liquid crystal (CLC) films were attached to the microcavity OLED between aluminum (Al) and silver (Ag). Sharply directed spontaneous emission was observed from microcavity OLEDs, in which a typical luminescent material, 8-hydroxyquinoline aluminum (Alq 3), with a broad emission spectrum was used for emitting layer. The introduction of the CLC film improved both the emission bandwidth and directionality, preserving the turn-on voltage and maximum brightness.

  6. High-field strong-focusing undulator designs for X-ray Linac Coherent Light Source (LCLS) applications

    International Nuclear Information System (INIS)

    Caspi, S.; Schlueter, R.; Tatchyn, R.

    1995-01-01

    Linac-driven X-Ray Free Electron Lasers (e.g., Linac Coherent Light Sources (LCLSs)), operating on the principle of single-pass saturation in the Self-Amplified Spontaneous Emission (SASE) regime typically require multi-GeV beam energies and undulator lengths in excess of tens of meters to attain sufficient gain in the 1 angstrom--0.1 angstrom range. In this parameter regime, the undulator structure must provide: (1) field amplitudes B 0 in excess of 1T within periods of 4cm or less, (2) peak on-axis focusing gradients on the order of 30T/m, and (3) field quality in the 0.1%--0.3% range. In this paper the authors report on designs under consideration for a 4.5--1.5 angstrom LCLS based on superconducting (SC), hybrid/PM, and pulsed-Cu technologies

  7. Emission Characteristics and Effect of Battery Drain in "Budget" Curing Lights.

    Science.gov (United States)

    AlShaafi, M M; Harlow, J E; Price, H L; Rueggeberg, F A; Labrie, D; AlQahtani, M Q; Price, R B

    2016-01-01

    Recently, "budget" dental light-emitting diode (LED)-based light-curing units (LCUs) have become available over the Internet. These LCUs claim equal features and performance compared to LCUs from major manufacturers, but at a lower cost. This study examined radiant power, spectral emission, beam irradiance profiles, effective emission ratios, and the ability of LCUs to provide sustained output values during the lifetime of a single, fully charged battery. Three examples of each budget LCU were purchased over the Internet (KY-L029A and KY-L036A, Foshan Keyuan Medical Equipment Co, and the Woodpecker LED.B, Guilin Woodpecker Medical Instrument Co). Major dental manufacturers provided three models: Elipar S10 and Paradigm (3M ESPE) and the Bluephase G2 (Ivoclar Vivadent). Radiant power emissions were measured using a laboratory-grade thermopile system, and the spectral emission was captured using a spectroradiometer system. Irradiance profiles at the tip end were measured using a modified laser beam profiler, and the proportion of optical tip area that delivered in excess of 400 mW/cm(2) (termed the effective emission ratio) was displayed using calibrated beam profile images. Emitted power was monitored over sequential exposures from each LCU starting at a fully charged battery state. The results indicated that there was less than a 100-mW/cm(2) difference between manufacturer-stated average tip end irradiance and the measured output. All the budget lights had smaller optical tip areas, and two demonstrated lower effective emission ratios than did the units from the major manufacturers. The budget lights showed discontinuous values of irradiance over their tip ends. One unit delivered extremely high output levels near the center of the light tip. Two of the budget lights were unable to maintain sustained and stable light output as the battery charge decreased with use, whereas those lights from the major manufacturers all provided a sustained light output for at least

  8. Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

    Science.gov (United States)

    Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg; PANDA Collaboration

    2017-06-01

    The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

  9. Measurement and optimization of the light collection uniformity in strongly tapered PWO crystals of the PANDA detector

    Energy Technology Data Exchange (ETDEWEB)

    Diehl, Stefan; Bremer, Daniel; Brinkmann, Kai-Thomas; Dormenev, Valery; Eissner, Tobias; Novotny, Rainer W.; Rosenbaum, Christoph; Zaunick, Hans-Georg

    2017-06-11

    The uniformity of the light collection is a crucial parameter for detectors based on inorganic scintillation crystals to guarantee a response proportional to the deposited energy. Especially in case of tapered crystals, like they are widely used to realize a 4π geometry of electromagnetic calorimeters (EMC) in high energy physics experiments, a strong non-uniformity is introduced by an additional focusing of the scintillation light due to the tapered geometry. The paper will discuss the determination and the reduction of the non-uniformity in strongly tapered lead tungstate crystals as used for the construction of the electromagnetic calorimeter of the PANDA detector at the future Facility for Antiproton and Ion Research (FAIR). Among different concepts for an uniformization a single de-polished lateral side face provided the optimum result with a remaining non-uniformity below 5% in good agreement with similar studies for the CMS ECAL at LHC. The impact on the achievable energy resolution in the energy regime of photons below 800 MeV is discussed in detail in comparison to GEANT4 simulations. The comparison of the response of two arrays with polished and de-polished crystals, respectively, shows in the latter case a significant improvement of the constant term of the parametrization of the energy resolution down to 0.5% accompanied by only very slight increase of the statistical term.

  10. Stimulated-emission-depletion microscopy with a multicolor stimulated-Raman-scattering light source.

    Science.gov (United States)

    Rankin, Brian R; Kellner, Robert R; Hell, Stefan W

    2008-11-01

    We describe a subdiffraction-resolution far-field fluorescence microscope employing stimulated emission depletion (STED) with a light source consisting of a microchip laser coupled into a standard single-mode fiber, which, via stimulated Raman scattering (SRS), yields a comb-like spectrum of seven discrete peaks extending from the fundamental wavelength at 532 nm to 620 nm. Each of the spectral peaks can be used as STED light for overcoming the diffraction barrier. This SRS light source enables the simple implementation of multicolor STED and provides a spectral output with multiple available wavelengths from green to red with potential for further expansion.

  11. Study of the Light Emission Process from the Double Chooz Photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, E.; Cerrada, M.; Crespo, J. I.; Gil-Botella, I.; Jimenez, S.; Lopez, M.; Novella, P.; Palomares, C.; Santorelli, R.; Verdugo, A.

    2012-09-13

    In this document we present a study of the light emitted by the base of a Hamamatsu R7081MOD-ASSY photomultiplier (PMT) of the same type used in the Double Chooz experiment. Several characteristic features of the light signal have been found in terms of amplitude, length and pulse shape. Additional investigations on the properties of the epoxy used to cover the photomultiplier base have been carried out. A possible explanation of the light emission process is discussed at the end of the study. (Author) 1 ref.

  12. Fission rate of nuclei at high excitation energy and emission of light particles

    International Nuclear Information System (INIS)

    Mersits, E.

    1991-10-01

    Light charged-particle emission has been measured for the reactions α + 238 U, 209 Bi, 232 Th at 118 MeV bombarding energies. The rate of particles detected in coincidence with fission fragments have been determined at high excitation energy. Modified precompound decay models and statistical models (program ALICE) have been used in an attempt to interpret the experimental data. The ratio of the level density parameter af/an was found to be 1.03 and 1.08, the temperature of neutron spectra was found to be 1.58 MeV and 1.33 MeV, for 238 U and 209 Bi, respectively. Analysing the experimental light-charged-particle spectra, there was no evidence for emission from the fission fragments which was in good agreement with calculations for the nucleus 209 Bi. On the other hand the theoretical emission spectra of 238 U predict great parts of such 'postfission' particles. Simplification in the model concerning the time of possible particle emission, that is, before the saddle-point and from the fragments, leads to the assumption of light particle emission between the saddle and the scission point

  13. Effects of cold temperature and ethanol content on VOC emissions from light-duty gasoline vehicles

    Science.gov (United States)

    Emissions of speciated volatile organic compounds (VOCs), including mobile source air toxics (MSATs), were measured in vehicle exhaust from three light-duty spark ignition vehicles operating on summer and winter grade gasoline (E0) and ethanol blended (E10 and E85) fuels. Vehicle...

  14. Slow-light enhancement of spontaneous emission in active photonic crystal waveguides

    DEFF Research Database (Denmark)

    Ek, Sara; Chen, Yaohui; Semenova, Elizaveta

    2012-01-01

    Photonic crystal defect waveguides with embedded active layers containing single or multiple quantum wells or quantum dots have been fabricated. Spontaneous emission spectra are enhanced close to the bandedge, consistently with the enhancement of gain by slow light effects. These are promising...

  15. STM-induced light emission from vacuum-evaporated gold film

    Indian Academy of Sciences (India)

    Administrator

    1271. STM-induced light emission from vacuum-evaporated gold film. J U AHAMED1,*, S KATANO2 and Y UEHARA2. 1Department of Applied Physics, Electronics and Communication Engineering, University of Chittagong,. Chittagong 4331, Bangladesh. 2Research Institute of Electrical Communication, Tohoku University, ...

  16. Cold Temperature Effects on Speciated VOC Emissions from Modern GDI Light-Duty Vehicles 1

    Science.gov (United States)

    In this study, speciated VOC emissions were characterized from three modern GDI light-duty vehicles. The vehicles were tested on a chassis dynamometer housed in a climate-controlled chamber at two temperatures (20 and 72 °F) using the EPA Federal Test Procedure (FTP) and a portio...

  17. A Versatile and Simple Approach to Generate Light Emission in Semiconductors Mediated by Electric Double Layers.

    Science.gov (United States)

    Pu, Jiang; Fujimoto, Taiyo; Ohasi, Yuki; Kimura, Shota; Chen, Chang-Hsiao; Li, Lain-Jong; Sakanoue, Tomo; Takenobu, Taishi

    2017-06-01

    The light-emitting device is the primary device for current light sources. In principle, conventional light-emitting devices need heterostructures and/or intentional carrier doping to form a p-n junction. This junction formation is, however, very difficult to achieve for most emerging semiconductors, and the fabrication of light-emitting devices is invariably a significant challenge. This study proposes a versatile and simple approach to realize light-emitting devices. This proposed device requires only a semiconducting film with two electrodes that are covered with an electrolyte. This unique structure achieves light emission at a voltage slightly larger than the bandgap energy of materials. This study applies this concept to emerging direct bandgap semiconductors, such as transition metal dichalcogenide monolayers and zinc oxide single crystals. These devices generate obvious light emission and provide sufficient evidence of the formation of a dynamic p-i-n junction or tunneling junction, presenting a versatile technique to develop optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  18. Evaluating Urban Methane Emissions with a Light Rail Vehicle Platform in Salt Lake City, UT

    Science.gov (United States)

    Mitchell, L.; Fasoli, B.; Crosman, E.; Lin, J. C.; Bowling, D. R.; Ehleringer, J. R.

    2016-12-01

    Urban environments are characterized by both spatial complexity and temporal variability, each of which present challenges for measurement strategies aimed at constraining estimates of greenhouse gas emissions and air quality. To address these challenges we initiated a project in December 2014 to measure trace species (CO2, CH4, O3, and Particulate Matter) by way of a Utah Transit Authority (UTA) electricity-powered light rail vehicle whose route traverses the metropolitan Salt Lake Valley in Utah, USA on an hourly basis, retracing the same route through commercial, residential, suburban, and rural typologies. Light rail vehicles present advantages as a measurement platform, including the absence of in-situ fossil fuel emissions, regular repeated transects across an urban region that provide both spatial and temporal information, and relatively low operating costs. We will present initial results investigating methane point sources and evaluating the magnitude and temporal characteristics of these emissions.

  19. Global mercury emissions from combustion in light of international fuel trading.

    Science.gov (United States)

    Chen, Yilin; Wang, Rong; Shen, Huizhong; Li, Wei; Chen, Han; Huang, Ye; Zhang, Yanyan; Chen, Yuanchen; Su, Shu; Lin, Nan; Liu, Junfeng; Li, Bengang; Wang, Xilong; Liu, Wenxin; Coveney, Raymond M; Tao, Shu

    2014-01-01

    The spatially resolved emission inventory is essential for understanding the fate of mercury. Previous global mercury emission inventories for fuel combustion sources overlooked the influence of fuel trading on local emission estimates of many countries, mostly developing countries, for which national emission data are not available. This study demonstrates that in many countries, the mercury content of coal and petroleum locally consumed differ significantly from those locally produced. If the mercury content in locally produced fuels were used to estimate emission, then the resulting global mercury emissions from coal and petroleum would be overestimated by 4.7 and 72%, respectively. Even higher misestimations would exist in individual countries, leading to strong spatial bias. On the basis of the available data on fuel trading and an updated global fuel consumption database, a new mercury emission inventory for 64 combustion sources has been developed. The emissions were mapped at 0.1° × 0.1° resolution for 2007 and at country resolution for a period from 1960 to 2006. The estimated global total mercury emission from all combustion sources (fossil fuel, biomass fuel, solid waste, and wildfires) in 2007 was 1454 Mg (1232-1691 Mg as interquartile range from Monte Carlo simulation), among which elementary mercury (Hg(0)), divalent gaseous mercury (Hg(2+)), and particulate mercury (Hg(p)) were 725, 548, and 181 Mg, respectively. The total emission from anthropogenic sources, excluding wildfires, was 1040 Mg (886-1248 Mg), with coal combustion contributing more than half. Globally, total annual anthropogenic mercury emission from combustion sources increased from 285 Mg (263-358 Mg) in 1960 to 1040 Mg (886-1248 Mg) in 2007, owing to an increased fuel consumption in developing countries. However, mercury emissions from developed countries have decreased since 2000.

  20. Light Emission Requires Exposure to the Atmosphere in Ex Vivo Bioluminescence Imaging

    Directory of Open Access Journals (Sweden)

    Yusuke Inoue

    2006-04-01

    Full Text Available The identification of organs bearing luciferase activity by in vivo bioluminescence imaging (BLI is often difficult, and ex vivo imaging of excised organs plays a complementary role. This study investigated the importance of exposure to the atmosphere in ex vivo BLI. Mice were inoculated with murine pro-B cell line Ba/F3 transduced with firefly luciferase and p190 BCR-ABL. They were killed following in vivo BLI, and whole-body imaging was done after death and then after intraperitoneal air injection. In addition, the right knee was exposed and imaged before and after the adjacent bones were cut. Extensive light signals were seen on in vivo imaging. The luminescence disappeared after the animal was killed, and air injection restored the light emission from the abdomen only, suggesting a critical role of atmospheric oxygen in luminescence after death. Although no substantial light signal at the right knee was seen before bone cutting, light emission was evident after cutting. In conclusion, in ex vivo BLI, light emission requires exposure to the atmosphere. Bone destruction is required to demonstrate luciferase activity in the bone marrow after death.

  1. Measuring the radial density distribution of light emission around the track of fast ions in nitrogen

    International Nuclear Information System (INIS)

    Ibach, T.

    1983-01-01

    For analysing the emission and stopping of ionization electrons (σ-electrons) emitted by fast ions passing through a gas, the radial density distribution of the light emission of the (0,0) transition of two optical bands in nitrogen have been measured. The systems selected for the epxeriments are the 2nd positive system (2.PS) at 337.1 nm primarily excited by low-energy electrons of about 20 eV, and the first negative system (1.NS) at 391.4 nm excited by faster electrons and simultaneous ionization. The equipment developed for the experiments records the light emission with a telescope-type optical arrangement including interference filters, allowing high local resolution and dynamics of the measured range. The measurements have been carried out at pressures between 0.133 and 13.3 mbar, using photons of energies ranging from 270 keV to 2.8 MeV, helium 3 beams of 270 keV/u and 500 keV/u, and neon beams of 270 keV/u. Abel's inversion applied to the distance functions allows calculation of the spatial light emission density which is normalized for a gas density of 1 g/cm 3 . The profiles of the two bands indicate that the σ-electron spectrum gets harder in outward direction. Next to the beam the impact density decreases faster with increasing ion energy than the stopping power (increasing interaction range of the σ-electrons). With photon beams, about half of the whole light emission in the 1. NS, and of the ionization, is induced by primary interactions of the ion beam. This proportion decreases at constant energy per nucleon with increasing atomic number of the ions as compared with the σ-electrons. The primary σ-emission gets harder with higher atomic numbers. (orig./HP) [de

  2. Hydrothermal synthesis and white light emission of cubic ZrO2:Eu3+ nanocrystals

    International Nuclear Information System (INIS)

    Meetei, Sanoujam Dhiren; Singh, Shougaijam Dorendrajit

    2014-01-01

    Highlights: • White light emitting cubic ZrO 2 :Eu 3+ nanocrystal is synthesized by hydrothermal technique. • Eu 3+ is used to stabilize crystalline phase and to get red counterpart of the white light. • Defect emission and Eu 3+ emission combined to give white light. • The white light emitted from this nanocrystal resembles vertical daylight of the Sun. • Lifetime corresponding to red counterpart of the sample is far longer than conventional white light emitters. -- Abstract: Production of white light has been a promising area of luminescence studies. In this work, white light emitting nanocrystals of cubic zirconia doped with Eu 3+ are synthesized by hydrothermal technique. The dopant Eu 3+ is used to stabilize crystalline phase to cubic and at the same time to get red counterpart of the white light. The synthesis procedure is simple and precursor required no further annealing for crystallization. X-ray diffraction patterns show the crystalline phase of ZrO 2 :Eu 3+ to be cubic and it is confirmed by Fourier Transform Infrared spectroscopy. From transmission electron microscopy images, size of the crystals is found to be ∼5 nm. Photoluminescence emission spectrum of the sample, on monitoring excitation at O 2− –Eu 3+ charge transfer state shows broad peak due to O 2− of the zirconia and that of Eu 3+ emission. Commission Internationale de l’éclairage co-ordinate of this nanocrystal (0.32, 0.34) is closed to that of the ideal white light (0.33, 0.33). Correlated color temperature of the white light (5894 K) is within the range of vertical daylight. Lifetime (1.32 ms) corresponding to 5 D 0 energy level of the Eu 3+ is found to be far longer than conventional red counterparts of white light emitters. It suggests that the ZrO 2 :Eu 3+ nanocrystals synthesized by hydrothermal technique may find applications in simulating the vertical daylight of the Sun

  3. THE REST-FRAME OPTICAL SPECTROSCOPIC PROPERTIES OF LY α -EMITTERS AT z  ∼ 2.5: THE PHYSICAL ORIGINS OF STRONG LY α EMISSION

    Energy Technology Data Exchange (ETDEWEB)

    Trainor, Ryan F. [Department of Astronomy, University of California, Berkeley, 501 Campbell Hall, Berkeley, CA 94720 (United States); Strom, Allison L.; Steidel, Charles C. [Cahill Center for Astrophysics, MC 249-17, 1200 E California Boulevard, Pasadena, CA 91125 (United States); Rudie, Gwen C., E-mail: trainor@berkeley.edu [Carnegie Observatories, 813 Santa Barbara Street, Pasadena, CA 91101 (United States)

    2016-12-01

    We present the rest-frame optical spectroscopic properties of 60 faint ( R {sub AB} ∼ 27; L ∼ 0.1 L {sub *}) Ly α -selected galaxies (LAEs) at z  ≈ 2.56. These LAEs also have rest-UV spectra of their Ly α emission line morphologies, which trace the effects of interstellar and circumgalactic gas on the escape of Ly α photons. We find that the LAEs have diverse rest-optical spectra, but their average spectroscopic properties are broadly consistent with the extreme low-metallicity end of the populations of continuum-selected galaxies selected at z  ≈ 2–3. In particular, the LAEs have extremely high [O iii] λ 5008/H β ratios (log([O iii]/H β ) ∼ 0.8) and low [N ii] λ 6585/H α ratios (log([N ii]/H α ) < 1.15). Coupled with a detection of the [O iii] λ 4364 auroral line, these measurements indicate that the star-forming regions in faint LAEs are characterized by high electron temperatures (T{sub e} ≈ 1.8 × 10{sup 4} K), low oxygen abundances (12 + log(O/H) ≈ 8.04, Z{sub neb} ≈ 0.22 Z {sub ⊙}), and high excitations with respect to their more luminous continuum-selected analogs. Several of our faintest LAEs have line ratios consistent with even lower metallicities, including six with 12 + log(O/H) ≈ 6.9–7.4 (Z {sub neb} ≈ 0.02–0.05 Z{sub ⊙}). We interpret these observations in light of new models of stellar evolution (including binary interactions) that have been shown to produce long-lived populations of hot, massive stars at low metallicities. We find that strong, hard ionizing continua are required to reproduce our observed line ratios, suggesting that faint galaxies are efficient producers of ionizing photons and important analogs of reionization-era galaxies. Furthermore, we investigate the physical trends accompanying Ly α emission across the largest current sample of combined Ly α and rest-optical galaxy spectroscopy, including both the 60 KBSS-Ly α LAEs and 368 more luminous galaxies at similar redshifts. We

  4. Evaluation of solid particle number and black carbon for very low particulate matter emissions standards in light-duty vehicles.

    Science.gov (United States)

    Chang, M-C Oliver; Shields, J Erin

    2017-06-01

    To reliably measure at the low particulate matter (PM) levels needed to meet California's Low Emission Vehicle (LEV III) 3- and 1-mg/mile particulate matter (PM) standards, various approaches other than gravimetric measurement have been suggested for testing purposes. In this work, a feasibility study of solid particle number (SPN, d50 = 23 nm) and black carbon (BC) as alternatives to gravimetric PM mass was conducted, based on the relationship of these two metrics to gravimetric PM mass, as well as the variability of each of these metrics. More than 150 Federal Test Procedure (FTP-75) or Supplemental Federal Test Procedure (US06) tests were conducted on 46 light-duty vehicles, including port-fuel-injected and direct-injected gasoline vehicles, as well as several light-duty diesel vehicles equipped with diesel particle filters (LDD/DPF). For FTP tests, emission variability of gravimetric PM mass was found to be slightly less than that of either SPN or BC, whereas the opposite was observed for US06 tests. Emission variability of PM mass for LDD/DPF was higher than that of both SPN and BC, primarily because of higher PM mass measurement uncertainties (background and precision) near or below 0.1 mg/mile. While strong correlations were observed from both SPN and BC to PM mass, the slopes are dependent on engine technologies and driving cycles, and the proportionality between the metrics can vary over the course of the test. Replacement of the LEV III PM mass emission standard with one other measurement metric may imperil the effectiveness of emission reduction, as a correlation-based relationship may evolve over future technologies for meeting stringent greenhouse standards. Solid particle number and black carbon were suggested in place of PM mass for the California LEV III 1-mg/mile FTP standard. Their equivalence, proportionality, and emission variability in comparison to PM mass, based on a large light-duty vehicle fleet examined, are dependent on engine

  5. 76 FR 76932 - Public Hearings for 2017 and Later Model Year Light-Duty Vehicle Greenhouse Gas Emissions and...

    Science.gov (United States)

    2011-12-09

    .../otaq/climate/regulations.htm or by searching the public dockets (NHTSA-2010-0131 (for the proposed rule... emissions from and improve fuel economy for light-duty vehicles for model years 2017-2025. The proposal... Program to reduce greenhouse gas emissions of light-duty vehicles for model years 2017-2025. The proposal...

  6. Core-shell conjugated microporous polymers: a new strategy for exploring color-tunable and -controllable light emissions.

    Science.gov (United States)

    Xu, Yanhong; Nagai, Atsushi; Jiang, Donglin

    2013-02-25

    A core-shell strategy is demonstrated for designing a conjugated microporous polymer that allows the tuning of light emission over a wide wavelength range in a controlled manner. The polymers not only emit efficiently with an eight-fold enhanced luminescence but also sustain light emissions, irrespective of solvent and state.

  7. Anomalous ULF Emissions and Their Possible Association with the Strong Earthquakes in Sumatra, Indonesia, during 2007-2012

    Directory of Open Access Journals (Sweden)

    Suaidi Ahadi

    2015-03-01

    Full Text Available Eleven strong Sumatran earthquakes, with their epicenter less than 550 km away from the Kototabang (KTB geomagnetic station (2007-2012, were studied to examine the occurrence of anomalous ultra-low frequency emissions (ULF-EM. Anomalous ULF signals, possibly associated with the earthquake’s precursors, were determined by the Welch ratio SZ/SH at 0.06 Hz at the KTB station. These ULF anomalies were then compared with geomagnetic data observed from two reference stations in Darwin and Davao, to prevent misinterpretation of global geomagnetic disturbances as precursors. This study aims to analyze the relationship between earthquake magnitude and hypocenter radius, and seismic index against lead time during ULF-EM anomalies. We used the polarization ratio Welch method in terms of power spectrum density to evaluate the geomagnetic data by overlapping windows and applying fast Fourier transform (FFT. The results showed anomalous variations in onset and lead time, determined using the standard deviation controlling the SZ/SH power pattern. Our positive correlation between lead time of ULF emission and earthquake magnitude as well as between lead time and seismic index. It shows a negative correlation between hypocenter distances to KTB station against lead time.

  8. Effects of the ZnO layer on the structure and white light emission properties of a ZnS:Mn/GaN nanocomposite system.

    Science.gov (United States)

    Wang, Cai-Feng; Hu, Bo

    2017-10-01

    ZnO films were inserted between the ZnS:Mn films and GaN substrates by pulsed laser deposition (PLD). The structure, morphology, and optical properties of the ZnS:Mn/ZnO/GaN nanocomposite systems have been investigated. X-ray diffraction results show that there are three diffraction peaks located at 28.4°, 34.4°, and 34.1°, which correspond to the β-ZnS(111), ZnO(002), and GaN(002) planes, respectively. Due to the insertion of ZnO films, the diffraction peak intensity of ZnS:Mn in ZnS:Mn/ZnO/GaN is stronger than that of ZnS:Mn in ZnS:Mn/GaN, and the full width at half-maximum is smaller. Though the transmittance of ZnS:Mn/ZnO films is slightly lower than that of ZnS:Mn films, the transmittance is still higher than 80%. Compared with ZnS:Mn/GaN, an ultraviolet (UV) emission at 387 nm (originated from the near-band emission of ZnO) and a green light emission at about 520 nm appeared in the photoluminescence (PL) spectra of ZnS:Mn/ZnO/GaN, in addition to the blue emission at 435 nm and the orange-red emission at 580 nm. The emission at 520 nm may be related to the deep-level emission from ZnO and the interface of ZnS:Mn/ZnO. The PL spectrum of ZnS:Mn/ZnO/GaN covers the visible region from the blue light to the red light (400-700 nm), and its color coordinate and color temperature are (0.3103,0.3063) and 6869 K, respectively, presenting strong white light emission.

  9. Electrically tunable strong light-matter coupling in a transition metal dichalcogenide monolayer embedded in a plasmonic crystal cavity

    Science.gov (United States)

    Scuri, Giovanni; Zhou, You; High, Alexander; Dibos, Alan; de Greve, Kristiaan; Polking, Mark; Juaregui, Luis; Wild, Dominik; Joe, Andrew; Pistunova, Kateryna; Lukin, Mikhail; Kim, Philip; Park, Hongkun

    Two-dimensional transition-metal dichalcogenide (TMDC) monolayers exhibit direct bandgap excitons with large binding energy. The optical response of TMDCs is electrically tunable over a broad wavelength range, making these 2D materials promising candidates for optoelectronic devices. In this work, we enhance exciton-plasmon coupling by embedding a single layer of tungsten diselenide (WSe2) into a plasmonic crystal cavity, which confines surface plasmon polaritons in an analogous manner to photonic crystal cavities. We observe strong light-matter interactions and the formation of microcavity polaritons when the cavity mode is on resonance with the exciton absorption in WSe2. Using the electrostatically controllable response of such excitons, we also demonstrate tunable vacuum Rabi splitting in such a system.

  10. Replacement policy of residential lighting optimized for cost, energy, and greenhouse gas emissions

    Science.gov (United States)

    Liu, Lixi; Keoleian, Gregory A.; Saitou, Kazuhiro

    2017-11-01

    Accounting for 10% of the electricity consumption in the US, artificial lighting represents one of the easiest ways to cut household energy bills and greenhouse gas (GHG) emissions by upgrading to energy-efficient technologies such as compact fluorescent lamps (CFL) and light emitting diodes (LED). However, given the high initial cost and rapidly improving trajectory of solid-state lighting today, estimating the right time to switch over to LEDs from a cost, primary energy, and GHG emissions perspective is not a straightforward problem. This is an optimal replacement problem that depends on many determinants, including how often the lamp is used, the state of the initial lamp, and the trajectories of lighting technology and of electricity generation. In this paper, multiple replacement scenarios of a 60 watt-equivalent A19 lamp are analyzed and for each scenario, a few replacement policies are recommended. For example, at an average use of 3 hr day-1 (US average), it may be optimal both economically and energetically to delay the adoption of LEDs until 2020 with the use of CFLs, whereas purchasing LEDs today may be optimal in terms of GHG emissions. In contrast, incandescent and halogen lamps should be replaced immediately. Based on expected LED improvement, upgrading LED lamps before the end of their rated lifetime may provide cost and environmental savings over time by taking advantage of the higher energy efficiency of newer models.

  11. White light emission from Er2O3 nano-powder excited by infrared radiation

    Science.gov (United States)

    Tabanli, Sevcan; Eryurek, Gonul; Di Bartolo, Baldassare

    2017-07-01

    Phosphors of Er2O3 nano-crystalline powders were synthesized by the thermal decomposition method. The structural properties of the nano-powders were investigated with XRD and HRTEM measurements. The cubic phase with a = 10.540 Å was the only phase observed. The average crystalline sizes and the widths of the grain size distribution curves were determined to be 27.2, 18.7 and 9.7 nm, respectively. The spectroscopic properties of the Er2O3 nano-powder were studied by measuring the luminescence, decay and rise patterns under 808 and 975 nm diode laser excitations. A peculiar effect of the pressure was observed since an optically active ion (Er) is part of the complex and not a dopant. A broad band of the white light emission combined with blue, green and red up-conversion emission bands of Er3+ ions were observed at 0.03 mbar pressure under both excitation wavelengths. Only, an intense broad band white light emission was observed from these nanocrystals at atmospheric pressure. Rising patterns show that the white light intensity reaches its maximum value more rapidly under 975 nm excitation although it decays slower than that of 808 nm excitation. The color quality parameters such as the color coordinate (CRI), correlated color temperature and the color rendering index were found to vary with both the excitation wavelength and the ambient pressure indicating that these nanocrystals could be considered good white light emitting source under the infrared excitations.

  12. Adjusting White OLEDs with Yellow Light Emission Phosphor Dye and Ultrathin NPB Layer Structure

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available High efficiency white organic light emission devices were demonstrated with phosphor material dye bis[2-(4-tertbutylphenylbenzothiazolato-N,C2′]iridium (acetylacetonate and ultrathin layer structure. The ultra thin layer be composed of 4,4′-bis[N-1-naphthyl-N-phenyl-amino]biphenyl (NPB or 4,4′-N,N′-dicarbazole-biphenyl : NPB mixed layer with blue light emission. The emission spectra of devices could be adjusted by different phosphor doping concentrations and ultra thin layer structure. Warm white light emitting device could be obtained with 5 wt% doping concentration and power efficiency of 9.93 lm/W at 5 V. Pure white light with Commission Internationale de l'Eclairage (CIE coordinates of (0.33, 0.30 and external quantum efficiency of 4.49% could be achieved with ultra thin layer device structure and 3 wt% phosphor doped device.

  13. The mechanism of light emission from a scanning tunnelling microscope operating in air.

    Science.gov (United States)

    Rogez, B; Cao, S; Dujardin, G; Comtet, G; Moal, E Le; Mayne, A; Boer-Duchemin, E

    2016-11-18

    The scanning tunnelling microscope (STM) may be used as a low-energy, electrical nanosource of surface plasmon polaritons and light. In this article, we demonstrate that the optimum mode of operation of the STM for maximum photon emission is completely different in air than in vacuum. To this end, we investigate the emission of photons, the variation in the relative tip-sample distance and the measured current as a function of time for an STM operating in air. Contrary to the case of an STM operating in vacuum, the measured current between the tip and sample for an STM in air is very unstable (rapidly fluctuating in time) when the applied voltage between the tip and sample is in the ∼1.5-3 V range (i.e., in the energy range of visible photons). The photon emission occurs in short (50 μs) bursts when the STM tip is closest to the sample. The current instabilities are shown to be a key ingredient for producing intense light emission from an STM operating in air (photon emission rate several orders of magnitude higher than for stable current). These results are explained in terms of the interplay between the tunnel current and the electrochemical current in the ubiquitous thin water layer that exists when working in air.

  14. Emissive ZnO-graphene quantum dots for white-light-emitting diodes

    Science.gov (United States)

    Son, Dong Ick; Kwon, Byoung Wook; Park, Dong Hee; Seo, Won-Seon; Yi, Yeonjin; Angadi, Basavaraj; Lee, Chang-Lyoul; Choi, Won Kook

    2012-07-01

    Hybrid nanostructures combining inorganic materials and graphene are being developed for applications such as fuel cells, batteries, photovoltaics and sensors. However, the absence of a bandgap in graphene has restricted the electrical and optical characteristics of these hybrids, particularly their emissive properties. Here, we use a simple solution method to prepare emissive hybrid quantum dots consisting of a ZnO core wrapped in a shell of single-layer graphene. We then use these quantum dots to make a white-light-emitting diode with a brightness of 798 cd m-2. The strain introduced by curvature opens an electronic bandgap of 250 meV in the graphene, and two additional blue emission peaks are observed in the luminescent spectrum of the quantum dot. Density functional theory calculations reveal that these additional peaks result from a splitting of the lowest unoccupied orbitals of the graphene into three orbitals with distinct energy levels. White emission is achieved by combining the quantum dots with other emissive materials in a multilayer light-emitting diode.

  15. Quantification of strong emissions of methane in the Arctic using spectral measurements from TANSO-FTS and IASI

    Science.gov (United States)

    Bourakkadi, Zakia; Payan, Sébastien; Bureau, Jérôme

    2015-04-01

    Methane is the second most important greenhouse gas after the carbon dioxide but it is 25 times more effective in contributing to the radiative forcing than the carbon dioxide(1). Since the pre-industrial times global methane concentration have more than doubled in the atmosphere. This increase is generally caused by anthropogenic activities like the massif use and extraction of fossil fuel, rice paddy agriculture, emissions from landfills... In recent years, several studies show that climate warming and thawing of permafrost act on the mobilization of old stored carbon in Arctic causing a sustained release of methane to the atmosphere(2),(3),(4). The methane emissions from thawing permafrost and methane hydrates in the northern circumpolar region will become potentially important in the end of the 21st centry because they could increase dramatically due to the rapid climate warming of the Artic and the large carbon pools stored there. The objective of this study is to evaluate and quantify methane strong emissions in this region of the globe using spectral measurements from the Thermal And Near Infrared Sensor for carbon Observations-Fourier Transform Spectrometer (TANSO-FTS) and the Infrared Atmospheric Sounding Interferometer (IASI). We use also the LMDZ-PYVAR model to simulate methane fluxes and to estimate how they could be observed by Infrared Sounders from space. To select spectra with high values of methane we developed a statistical approach based on the singular value decomposition. Using this approach we can identify spectra over the important emission sources of methane and we can by this way reduce the number of spectra to retrieve by an line-by-line radiative transfer model in order to focus on those which contain high amount of methane. In order to estimate the capacity of TANSO-FTS and IASI to detect peaks of methane emission with short duration at quasi-real time, we used data from MACC (Monitoring Atmospheric Composition and Climate) simulations

  16. Ho3+-doped strontium-aluminium-bismuth-borate glasses for green light emission.

    Science.gov (United States)

    Rajesh, D; Dhamodhara Naidu, M; Ratnakaram, Y C; Balakrishna, A

    2014-11-01

    Strontium-aluminium-bismuth-borate glasses (SAlBiB) doped with different concentrations of Ho(3+) were prepared using conventional melt quenching technique and their structural and optical properties investigated. X-ray diffraction and scanning electron microscopy analysis were used to study the structural properties. Optical properties were studied by measuring the optical absorption and visible luminescence spectra. The Judd-Ofelt (J-O) theory was applied to evaluate J-O intensity parameters, Ω(λ) (λ = 2, 4 and 6). Using J-O intensity parameters, radiative properties such as spontaneous transition probabilities (A(R)), branching ratios (β(R)) and radiative lifetimes (τ(R)) were determined. From the emission spectra, a strong green emission nearly at 549 nm corresponding to the transition, (5)S2 ((5)F4)→(5)I(8) was observed. Emission peak positions (λ(P)), effective bandwidths (Δλ(eff)) and stimulated emission cross-sections (σ(p)) were calculated for the observed emission transitions, (5)F3 →(5)I(8), (5)S2((5)F4)→(5)I(8) and (5)F5 →(5)I(8) of Ho(3+) in all the glass matrices. Chromaticity color coordinates were calculated using the emission spectra. The experimental results suggest that SAlBiB glass matrix with 1.5 mol% of Ho(3+) has better emission properties. Copyright © 2014 John Wiley & Sons, Ltd.

  17. Emission enhancement, light extraction and carrier dynamics in InGaAs/GaAs nanowire arrays

    Science.gov (United States)

    Kivisaari, Pyry; Chen, Yang; Anttu, Nicklas

    2018-03-01

    Nanowires (NWs) have the potential for a wide range of new optoelectronic applications. For example, light-emitting diodes that span over the whole visible spectrum are currently being developed from NWs to overcome the well known green gap problem. However, due to their small size, NW devices exhibit special properties that complicate their analysis, characterization, and further development. In this paper, we develop a full optoelectronic simulation tool for NW array light emitters accounting for carrier transport and wave-optical emission enhancement (EE), and we use the model to simulate InGaAs/GaAs NW array light emitters with different geometries and temperatures. Our results show that NW arrays emit light preferentially to certain angles depending on the NW diameter and temperature, encouraging temperature- and angle-resolved measurements of NW array light emission. On the other hand, based on our results both the EE and light extraction efficiency can easily change by at least a factor of two between room temperature and 77 K, complicating the characterization of NW light emitters if conventional methods are used. Finally, simulations accounting for surface recombination emphasize its major effect on the device performance. For example, a surface recombination velocity of 104 cm s-1 reported earlier for bare InGaAs surfaces results in internal quantum efficiencies less than 30% for small-diameter NWs even at the temperature of 30 K. This highlights that core-shell structures or high-quality passivation techniques are eventually needed to achieve efficient NW-based light emitters.

  18. An assessment of the real-world driving gaseous emissions from a Euro 6 light-duty diesel vehicle using a portable emissions measurement system (PEMS)

    Science.gov (United States)

    Luján, José M.; Bermúdez, Vicente; Dolz, Vicente; Monsalve-Serrano, Javier

    2018-02-01

    Recent investigations demonstrated that real-world emissions usually exceed the levels achieved in the laboratory based type approval processes. By means of on-board emissions measurements, it has been shown that nitrogen oxides emitted by diesel engines substantially exceed the limit imposed by the Euro 6 regulation. Thus, with the aim of complementing the worldwide harmonized light vehicles test cycle, the real driving emissions cycle will be introduced after 1 September 2017 to regulate the vehicle emissions in real-world driving situations. This paper presents on-board gaseous emissions measurements from a Euro 6 light-duty diesel vehicle in a real-world driving route using a portable emissions measurement system. The test route characteristics follow the requirements imposed by the RDE regulation. The analysis of the raw emissions results suggests that the greatest amount of nitrogen oxides and nitrogen dioxide are emitted during the urban section of the test route, confirming that lower speeds with more accelerations and decelerations lead to higher nitrogen oxides emissions levels than constant high speeds. Moreover, the comparison of the two calculation methods proposed by the real driving emissions regulation has revealed emissions rates differences ranging from 10% to 45% depending on the pollutant emission and the trip section considered (urban or total). Thus, the nitrogen oxides emissions conformity factor slightly varies from one method to the other.

  19. Excitation light source dependence of emission in Sn2+-Ce3+ codoped ZnO-P2O5 glasses

    OpenAIRE

    Masai, Hirokazu; Hino, Yusuke; Yanagida, Takayuki; Fujimoto, Yutaka; Fukuda, Kentaro; Yoko, Toshinobu

    2013-01-01

    Correlation between excitation light source and the emission property of Sn^{2+}-Ce^{3+} co-doped zinc phosphate glasses is examined. Although photoluminescence (PL) peaks of both Sn^{2+}and Ce^{3+} shifted with increasing amount of Ce^{3+}, there was little energy resonance between Sn^{2+} and Ce^{3+} emission centers. On the other hand, radioluminescence (RL) spectra excited by X-ray was independent of the Ce concentration, indicating that emission was mainly observed from Sn^{2+} emission ...

  20. Modeling and simulations of light emission and propagation in open nanophotonic systems

    DEFF Research Database (Denmark)

    de Lasson, Jakob Rosenkrantz

    for computing and normalizing quasi-normal modes in extended systems, and comparing to numerically exact calculations, the theory correctly predicts a slight asymmetry (one cavity) and a peak and a dip (two cavities) in the local density of states spectra. Next, the photonic crystal waveguide is interfaced......Light emission and propagation in photonic crystal membranes are studied theoretically, with an emphasis on waveguides, slow light effects, and coupled cavity-waveguide systems. A Bloch mode expansion formalism for optical modeling of photonic crystal membranes is presented, and perfectly matched...... layer boundary conditions are introduced to emulate the inherent openness of the photonic crystal membrane. The impact of the computational domain size and perfectly matched layer parameters on dipole emission in a photonic crystal membrane waveguide is investigated, and we find the associated...

  1. Ultraviolet radiation and blue-light emissions from spotlights incorporating tungsten halogen lamps

    CERN Document Server

    MacKinlay, Alistair F; Whillock, M J

    1989-01-01

    This report summarises measurements of the ultraviolet radiation and blue-light emissions from eleven 'desk-top' tungsten halogen (quartz) lamps and one 'floor-standing' tungsten halogen (quartz) lamp available in the UK. Values of occupational hazard weighted and erythemally weighted ultraviolet radiation irradiance and measurements and relevant calculations of blue-light hazards are presented. It is concluded that the safety design of some desk-top tungsten halogen lamps is inadequate to prevent unnecessary exposure of the skin to potentially harmful ultraviolet radiation. It is recommended that all tungsten halogen lamps should have sufficient filtration to reduce their ultraviolet emissions to an acceptably low level. As long as the comfort aversion responses of the eye are respected, direct viewing of the lamps examined should not constitute a retinal hazard.

  2. Low light CMOS contact imager with an integrated poly-acrylic emission filter for fluorescence detection.

    Science.gov (United States)

    Dattner, Yonathan; Yadid-Pecht, Orly

    2010-01-01

    This study presents the fabrication of a low cost poly-acrylic acid (PAA) based emission filter integrated with a low light CMOS contact imager for fluorescence detection. The process involves the use of PAA as an adhesive for the emission filter. The poly-acrylic solution was chosen due its optical transparent properties, adhesive properties, miscibility with polar protic solvents and most importantly its bio-compatibility with a biological environment. The emission filter, also known as an absorption filter, involves dissolving an absorbing specimen in a polar protic solvent and mixing it with the PAA to uniformly bond the absorbing specimen and harden the filter. The PAA is optically transparent in solid form and therefore does not contribute to the absorbance of light in the visible spectrum. Many combinations of absorbing specimen and polar protic solvents can be derived, yielding different filter characteristics in different parts of the spectrum. We report a specific combination as a first example of implementation of our technology. The filter reported has excitation in the green spectrum and emission in the red spectrum, utilizing the increased quantum efficiency of the photo sensitive sensor array. The thickness of the filter (20 μm) was chosen by calculating the desired SNR using Beer-Lambert's law for liquids, Quantum Yield of the fluorophore and the Quantum Efficiency of the sensor array. The filters promising characteristics make it suitable for low light fluorescence detection. The filter was integrated with a fully functional low noise, low light CMOS contact imager and experimental results using fluorescence polystyrene micro-spheres are presented.

  3. Silicon nanocrystal-based photonic crystal slabs with broadband and efficient directional light emission

    Czech Academy of Sciences Publication Activity Database

    Ondič, Lukáš; Varga, Marián; Pelant, Ivan; Valenta, J.; Kromka, Alexander; Elliman, R. G.

    2017-01-01

    Roč. 7, č. 1 (2017), s. 1-8, č. článku 5763. ISSN 2045-2322 R&D Projects: GA ČR GJ16-09692Y; GA MŠk(CZ) LD15003 Institutional support: RVO:68378271 Keywords : photonic crystal slab * silicon nanocrystals * light emission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 4.259, year: 2016

  4. Autocorrelation analysis of plasma plume light emissions in deep penetration laser welding of steel

    Czech Academy of Sciences Publication Activity Database

    Mrňa, Libor; Šarbort, Martin; Řeřucha, Šimon; Jedlička, Petr

    2017-01-01

    Roč. 29, č. 1 (2017), s. 1-10, č. článku 012009. ISSN 1042-346X R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : laser welding * plasma plume * light emissions * autocorrelation analysis * weld depth Subject RIV: BH - Optics, Masers, Lasers OBOR OECD: Optics (including laser optics and quantum optics) Impact factor: 1.492, year: 2016

  5. Treatment of rosacea patients with broadband pulse light emission using smooth pulse and photon recirculation technologies

    Directory of Open Access Journals (Sweden)

    A. A. Kubanova

    2015-01-01

    Full Text Available Goal of the study. To assess the efficacy and safety of using broadband pulse light emission with smooth pulse and photon recirculation technologies in the treatment of patients suffering from erythematous and papulous subtypes of rosacea. Materials and methods. Sixty rosacea patients (21 male and 39 female at the age of 25-65 including 38 patients with erythematous and 22 patients with papulous subtypes of rosacea underwent treatment using broadband pulse light emission (5-8 treatment sessions. Results. After one month of treatment with broadband pulse light emission using smooth pulse and photon recirculation technologies: 68.4% of patients with the erythematous subtype had clinical recovery, and 31.6% - improvement; 27.2% of patients with the papulous subtype - clinical recovery, 54.5% - improvement, and 18.3% had no effect. After 5 months of treatment most of the patients still had a positive effect of the therapy, yet 21.1% of patients with the erythematous subtype and 11% of patients with the papulous subtype had single telangiectasias, increased erythema and single papules. After 10 months of treatment 44.7% of patients with the erythematous subtype of rosacea had an increase in the number of enlarged vessels, and 18.3% of patients with the papulous subtype had signs of a recurrence of the disease. Conclusion. The use of broadband pulse light emission with smooth pulse and photon recirculation technologies has a multiple, painless and significant effect on large lesions in the treatment of patients suffering from erythematous and papulous subtypes of rosacea.

  6. Strongly turbulent ionizing shock wave as the mechanism for the first neutron emission in the dense plasma focus discharge

    International Nuclear Information System (INIS)

    Kobata, T.

    1987-01-01

    It is well known that high temperature thermo-nuclear plasma of several keV is very difficult to exist in the dense and small radius plasma column. So, at any time the high neutron yield from the dense plasma focus has had the tendency to be explained by the beam target mechanism based on the observation of the high energy beam emissions. However the manner of neutron emission is very complex and different among the devices and from shot to shot. Especially it is difficult to explain the first neutron emission by the beam target mechanism which is coincide with the formation of very dense plasma column. There is the ionizing shock wave in front of the plasma sheet and the gas is fully ionized after the shock wave because the Mach-number against the filling gas is very large, M--100. The thickness of the shock wave is very thin, 1≤0.5 mm for the discharge condition that the speed of the plasma sheet V/sub sh/ is 1--2 x 10/sup 7/ cm/sec and the discharge gas pressure is several Torr. The intensity of the magnetic field penetrated into the shock wave from the back side of the plasma sheet at the last converging phase will be the order of 1 kG. The plasma density in the shock wave will be n=4--9.10/sup 17//cm/sup 3/ because the density jump in the very strong shock limit is 6 times of the base gas density. Then the Alfven speed b=B/sub θ//(4πrho)/sup 1/2/ calculated from these density and magnetic field is 2.4--1.6 x 10/sup 6/ cm/sec. Similarly the sonic speed a= (γkT/m)/sup 1/2/ in the plasma is also the same order, i.e. a=2--4x10/sup 6/ cm/sec, for the temperature of 10--50 eV expected from the shock wave heating

  7. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    Energy Technology Data Exchange (ETDEWEB)

    Hua, Wang, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Du, Xiaogang [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Su, Wenming, E-mail: wmsu2008@sinano.ac.cn, E-mail: wanghua001@tyut.edu.cn; Zhang, Dongyu [Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China); Lin, Wenjing [Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan 030024 (China); Research Center of Advanced Materials Science and Technology, Taiyuan University of Technology, Taiyuan 030024 (China); Printable Electronics Research Centre, Suzhou Institute of Nano-Tech and Nano-Bionics, CAS, suzhou 215123 (China)

    2014-02-15

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4{sup ′}-N,N{sup ′}-dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N{sup ′})iridium(III) (Ir(2-phq){sub 3}) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2{sup ′}]picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m{sup 2}. More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED.

  8. Full phosphorescent white-light organic light-emitting diodes with improved color stability and efficiency by fine tuning primary emission contributions

    International Nuclear Information System (INIS)

    Hua, Wang; Du, Xiaogang; Su, Wenming; Zhang, Dongyu; Lin, Wenjing

    2014-01-01

    In this paper, a novel type of white-light organic light emitting diode (OLED) with high color stability was reported, in which the yellow-light emission layer of (4,4 ′ -N,N ′ -dicarbazole)biphenyl (CBP) : tris(2-phenylquinoline-C2,N ′ )iridium(III) (Ir(2-phq) 3 ) was sandwiched by double blue-light emission layers of 1,1-bis-[(di-4-tolylamino)pheny1]cyclohexane (TAPC) : bis[4,6-(di-fluorophenyl)-pyridinato-N,C2 ′ ]picolinate (FIrpic) and tris[3-(3-pyridyl)mesityl]borane (3TPYMB):FIrpic. And, it exhibited the maximum current efficiency of 33.1 cd/A, the turn-on voltage at about 3 V and the maximum luminance in excess of 20000 cd/m 2 . More important, it realized very stable white-light emission, and its CIE(x, y) coordinates only shift from (0.34, 0.37) to (0.33, 0.37) as applied voltage increased from 5 V to 12 V. It is believed that the new scheme in emission layer of white-light OLED can fine tune the contribution of primary emission with applied voltage changed, resulting in high quality white-light OLED

  9. Study of organic light emitting devices (OLEDs) with optimal emission efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Jai [School of Engineering and IT, B-purple 12, Faculty of EHS, Charles Darwin University, Darwin, NT 0909 (Australia)

    2010-04-15

    The external emission efficiency of organic light emitting devices (OLEDs) is analysed by studying the rate of spontaneous emission of both singlet and triplet excitons and their corresponding radiative lifetimes. Rates of spontaneous emissions are calculated from the first order perturbation theory using the newly discovered time-dependent spin-orbit-exciton-photon interaction operator as the perturbation operator. It is clearly shown how the new interaction operator is responsible for attracting triplet excitons to a phosphor (heavy metal atom) and then it flips the spins to a singlet configuration. Thus, the spin forbidden transition becomes spin allowed. Calculated rates agree with the experimental results qualitatively. Results are of general interests for OLED studies. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. White light emission from an exciplex interface with a single emitting layer (Conference Presentation)

    Science.gov (United States)

    Bernal, Wilson; Perez-Gutierrez, Enrique; Agular, Andres; Barbosa G, J. Oracio C.; Maldonado, Jose L.; Meneses-Nava, Marco Antonio; Rodriguez Rivera, Mario A.; Rodriguez, Braulio

    2017-02-01

    Efficient solid state lighting devices based in inorganic emissive materials are now available in the market meanwhile for organic emissive materials still a lot of research work is in its way. [1,2] In this work a new organic emissive material based on carbazole, N-(4-Ethynylphenyl) carba-zole-d4 (6-d4), is used as electron-acceptor and commercial PEDOT:PSS as the electron-donor to obtain white emission. Besides the HOMO-LUMO levels of materials the white emission showed dependence on the films thicknesses and applied voltages. In here it is reported that by diminishing the thickness of the PEDOT:PSS layer, from 60 to 35 nm, and by keeping the derivative carbazole layer constant at 100 nm the electro-luminescence (EL) changed from emissive exciton states to the mixture of emissive exciton and exciplex states. [3] For the former thicknesses no white light was obtained meanwhile for the later the EL spectra broadened due to the emission of exciplex states. Under this condition, the best-achieved CIE coordinate was (0.31,0.33) with a driving voltage of 8 V. To lower the driving voltage of the devices a thin film of LiF was added between the derivative of carbazol and cathode but the CIE coordinates changed. The best CIE coordinates for this case were (0.29, 0.34) and (0.32, 0.37) with driving voltage of about 6.5 V. Acknowledgments: CeMie-Sol/27 (Mexico) 207450 References [1] Timothy L Dawson, Society of Dyers and Colourists, Color. Technol., 126, 1-10 (2010), doi: 10.1111/j.1478-4408.2010.00220.x [2] G. M. Farinola, R. Ragni, Journal of Solid State Lighting, 2:9 (2015), doi: 10.1186/s40539-015-0028-7. [3] E. Angioni, et al, J. Mater. Chem. C, 2016, 4, 3851, doi: 10.1039/c6tc00750c.

  11. The electrical properties of a strongly disordered system based on lightly doped germanium compensated by disordered regions

    International Nuclear Information System (INIS)

    Evseev, V.A.; Konopleva, R.F.; Yuferev, A.A.

    1976-01-01

    A study was made of lightly doped (Nsub(Sb) approximately 10 15 cm -3 ) n-Ge, heavily compensated (K = Nsub(A)/N sub(D) approximately 1) by fast neutrons from a reactor. Irradiation is shown to produce, near n-p conversion (annealing has the same effect near p-n conversion), a random relief of electrostatic potential which is caused by the overlap of the space-charge regions surrounding disordered regions (DR). the random potential field results in a spatial 'bending' of the whole band spectrum of germanium, similar to the way it is observed in amorphous semiconductors because of their disorder. Experiments show the conduction in the DR overlap region to be of an activated nature, associated with the ejection of carriers to the corresponding 'percolation' levels. The activation energy of such conduction varies with the degree of compensation. The shift of the Fermi level depends on the degree of compensation here in a much more sensitive way than in the case of compensation by chemical impurities. The properties of Ge obtained by DR overlap and by compensation with chemical impurities are compared. A superlinear I-V characteristic producing the switching effect is observed in strong electric fields (E approximately 10 3 V cm -1 ). A suggestion is made that a study of disordered systems, based on lightly doped germanium which is compensated with DRs produced by high-energy particles, should both help to obtain new information on the parameters of the DRs proper and help to simulate the properties of the amorphous semiconductors. (author)

  12. A single haplotype hyposensitive to light and requiring strong vernalization dominates Arabidopsis thaliana populations in Patagonia, Argentina.

    Science.gov (United States)

    Kasulin, Luciana; Rowan, Beth A; León, Rolando J C; Schuenemann, Verena J; Weigel, Detlef; Botto, Javier F

    2017-07-01

    The growing collection of sequenced or genotyped Arabidopsis thaliana accessions includes mostly individuals from the native Eurasian and N. African range and introduced North American populations. Here, we describe the genetic and phenotypic diversity, along with habitats and life history, of A. thaliana plants collected at the southernmost end of its worldwide distribution. Seed samples were harvested from plants growing in four sites within a ~3500-km 2 -area in Patagonia, Argentina, and represent the first germplasm to be collected in South America for this species. Whole-genome resequencing revealed that plants from the four sites and a Patagonia herbarium specimen collected in 1967 formed a single haplogroup (Pat), indicating that the phenotypic variation observed in the field reflected plastic responses to the environment. admixture and principal components analyses suggest that the ancestor of the Pat haplogroup either came from Italy or the Balkan/Caucasus regions of Eurasia. In the laboratory, plants from the Pat haplogroup were hyposensitive to continuous red (Rc) and shade light, with corresponding changes in the expression of phytochrome signalling genes. Pat had higher PIF3 and PIF5 and lower HY5 expression under Rc light; and lower expression of PIL1, ATHB2 and HFR1 under shade compared to Col-0. In addition, Pat plants had a strong vernalization requirement associated with high levels of FLC expression. We conclude that including Pat in studies of natural variation and in comparison with other introduced populations will provide additional information for association studies and allow for a more detailed assessment of the demographic events following colonization. © 2017 John Wiley & Sons Ltd.

  13. Strong Energy-momentum Dispersion of Phonon Dressed Carriers in the Lightly Doped Band Insulator SrTiO3

    Energy Technology Data Exchange (ETDEWEB)

    Meevasana, Warawat

    2010-05-26

    Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is the perovskite SrTiO{sub 3} (STO), well known for its giant dielectric constant of 10000 at low temperature, exceeding that of La{sub 2}CuO{sub 4} by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped SrTiO{sub 3}. Comparing to lightly doped Mott insulators, we find the signatures of only moderate electron-phonon coupling: a dispersion anomaly associated with the low frequency optical phonon with a {lambda}{prime} {approx} 0.3 and an overall bandwidth renormalization suggesting an overall {lambda}{prime} {approx} 0.7 coming from the higher frequency phonons. Further, we find no clear signatures of the large pseudogap or small polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.

  14. Influence of Emission Spectrum and Irradiance on Light Curing of Resin-Based Composites.

    Science.gov (United States)

    Shimokawa, Cak; Sullivan, B; Turbino, M L; Soares, C J; Price, R B

    This study examined the influence of different emission spectra (single-peak and broad-spectrum) light-curing units (LCUs) delivering the same radiant exposures at irradiance values of 1200 or 3600 mW/cm 2 on the polymerization and light transmission of four resin-based composites (RBCs). Two prototype LCUs that used the same light tip, but were either a single-peak blue or a broad-spectrum LED, were used to deliver the same radiant exposures to the top surfaces of the RBCs using either standard (1200 mW/cm 2 ) or high irradiance (3600 mW/cm 2 ) settings. The emission spectrum and radiant power from the LCUs were measured with a laboratory-grade integrating sphere coupled to a spectrometer, and the light beam was assessed with a beam profiler camera. Four RBCs (Filtek Supreme Ultra A2, Tetric EvoCeram A2, Tetric EvoCeram T, and TPH Spectra High Viscosity A2) were photoactivated using four different light conditions: single-peak blue/standard irradiance, single-peak blue/high irradiance, broad-spectrum/standard irradiance, and broad-spectrum/high irradiance. The degree of conversion (N=5) and microhardness at the top and bottom of 2.3-mm-diameter by 2.5-mm-thick specimens (N=5) were analyzed with analysis of variance and Tukey tests. The real-time light transmission through the RBCs was also measured. For all light conditions, the 2.3-mm-diameter specimens received a homogeneous irradiance and spectral distribution. Although similar radiant exposures were delivered to the top surfaces of the RBCs, the amount of light energy emitted from the bottom surfaces was different among the four RBCs, and was also greater for the single-peak lights. Very little violet light (wavelengths below 420 nm) reached the bottom of the 2.5-mm-thick specimens. The degree of conversion and microhardness results varied according to the RBC (pspectrum lights, while at the bottom, where little violet light was observed, the results were equal or higher when they were photoactivated with

  15. Propagation of a strong x-ray pulse: Pulse compression, stimulated Raman scattering, amplified spontaneous emission, lasing without inversion, and four-wave mixing

    International Nuclear Information System (INIS)

    Sun Yuping; Wang Chuankui; Liu Jicai; Gel'mukhanov, Faris

    2010-01-01

    We study the compression of strong x-ray pulses from x-ray free-electron lasers (XFELs) propagating through the resonant medium of atomic argon. The simulations are based on the three-level model with the frequency of the incident x-ray pulse tuned in the 2p 3/2 -4s resonance. The pulse propagation is accompanied by the self-seeded stimulated resonant Raman scattering (SRRS). The SRRS starts from two channels of amplified spontaneous emission (ASE), 4s-2p 3/2 and 3s-2p 3/2 , which form the extensive ringing pattern and widen the power spectrum. The produced seed field triggers the Stokes ASE channel 3s-2p 3/2 . The population inversion is quenched for longer propagation distances where the ASE is followed by the lasing without inversion (LWI), which amplifies the Stokes component. Both ASE and LWI reshape the input pulse: The compressed front part of the pulse (up to 100 as) is followed by the long tail of the ringing and beating between the pump and Stokes frequencies. The pump pulse also generates weaker Stokes and anti-Stokes fields caused by four-wave mixing. These four spectral bands have fine structures caused by the dynamical Stark effect. A slowdown of the XFEL pulse up to 78% of the speed of light in vacuum is found because of a large nonlinear refractive index.

  16. 40 CFR 86.1811-09 - Emission standards for light-duty vehicles, light-duty trucks and medium-duty passenger vehicles.

    Science.gov (United States)

    2010-07-01

    ... AND IN-USE HIGHWAY VEHICLES AND ENGINES (CONTINUED) General Compliance Provisions for Control of Air Pollution From New and In-Use Light-Duty Vehicles, Light-Duty Trucks, and Complete Otto-Cycle Heavy-Duty.... Additionally, this section applies to hybrid electric vehicles (HEVs) and zero emission vehicles (ZEVs). Unless...

  17. Tuning the light emission of novel donor-acceptor phenoxazine dye-based materials towards the red spectral range

    Science.gov (United States)

    Damaceanu, Mariana-Dana; Constantin, Catalin-Paul

    2018-04-01

    A novel red fluorescent push-pull system able to generate an intramolecular charge-transfer (ICT) complex was synthesized. The novel dye (R-POX) combines some structural features which are rarely encountered in the design of other push-pull systems: hexyl-substituted phenoxazine as donor moiety, divinylketone as π-linker, and p-fluorobenzene as electron acceptor group. The relationship between the structural motif, photo-physical and electrochemical properties by UV-Vis absorption, photoluminescence and cyclic voltammetry was thoroughly investigated both as red dopant in poly(methylmethacrylate) (PMMA) or polyimide (PI) matrix, and non-doped host emitter. The molecular rigid cores of the synthesized dye formed supramolecular rod-like structures in condensed phase with a strong impact on the emissive centers. The aggregation was totally suppressed when the dye was used as dopant in an amorphous polymeric matrix, such as PMMA or PI. Electrochemical measurements revealed the dye ability for both hole and electron injection and transport. The fluorescence emission was found to be highly sensitive to solvent polarity, rendering blue-green, yellow, orange and red light emission in different organic solvents. The absolute fluorescence quantum yield reached 39.57% in solution, and dropped to 1.2% in solid state and to 14.01% when the dye was used as dopant in PMMA matrix. According to the available CIE 1931 standard, R-POX emitted pure and saturated red light of single wavelength with chromaticity coordinates very close to those of National Television System Committee (NTSC) standard red colour. The R-POX photo-optical features were compared to those of the commercial red emitter 6, 13-diphenylpentacene.

  18. A qubit strongly coupled to a resonant cavity: asymmetry of the spontaneous emission spectrum beyond the rotating wave approximation

    Energy Technology Data Exchange (ETDEWEB)

    Cao, X [Department of Physics and Institute of Theoretical Physics and Astrophysics, Xiamen University, Xiamen, 361005 (China); You, J Q; Nori, F [Advanced Science Institute, RIKEN, Wako-shi 351-0198 (Japan); Zheng, H, E-mail: xfcao@xmu.edu.cn [Department of Physics, Shanghai Jiao Tong University, Shanghai 200240 (China)

    2011-07-15

    We investigate the spontaneous emission (SE) spectrum of a qubit in a lossy resonant cavity. We use neither the rotating-wave approximation nor the Markov approximation. For the weak-coupling case, the SE spectrum of the qubit is a single peak, with its location depending on the spectral density of the qubit environment. Then, the asymmetry (of the location and heights of the two peaks) of the two SE peaks (which are related to the vacuum Rabi splitting) changes as the qubit-cavity coupling increases. Explicitly, for a qubit in a low-frequency intrinsic bath, the height asymmetry of the splitting peaks is enhanced as the qubit-cavity coupling strength increases. However, for a qubit in an Ohmic bath, the height asymmetry of the spectral peaks is inverted compared to the low-frequency bath case. With further increasing the qubit-cavity coupling to the ultra-strong regime, the height asymmetry of the left and right peaks is slightly inverted, which is consistent with the corresponding case of a low-frequency bath. This inversion of the asymmetry arises from the competition between the Ohmic bath and the cavity bath. Therefore, after considering the anti-rotating terms, our results explicitly show how the height asymmetry in the SE spectrum peaks depends on the qubit-cavity coupling and the type of intrinsic noise experienced by the qubit.

  19. Characterization of the spontaneous light emission of the PMTs used in the Double Chooz experiment

    Science.gov (United States)

    Abe, Y.; Abrahão, T.; Alt, C.; Appel, S.; Bekman, I.; Bergevin, M.; Bezerra, T. J. C.; Bezrukov, L.; Blucher, E.; Brugière, T.; Buck, C.; Busenitz, J.; Cabrera, A.; Calvo, E.; Camilleri, L.; Carr, R.; Cerrada, M.; Chauveau, E.; Chimenti, P.; Collin, A. P.; Conover, E.; Conrad, J. M.; Crespo-Anadón, J. I.; Crum, K.; Cucoanes, A. S.; Damon, E.; Dawson, J. V.; de Kerret, H.; Dhooghe, J.; Dietrich, D.; Djurcic, Z.; dos Anjos, J. C.; Dracos, M.; Etenko, A.; Fallot, M.; Felde, J.; Fernandes, S. M.; Fischer, V.; Franco, D.; Franke, M.; Furuta, H.; Gil-Botella, I.; Giot, L.; Göger-Neff, M.; Gomez, H.; Gonzalez, L. F. G.; Goodenough, L.; Goodman, M. C.; Haag, N.; Hara, T.; Haser, J.; Hellwig, D.; Hofmann, M.; Horton-Smith, G. A.; Hourlier, A.; Ishitsuka, M.; Jiménez, S.; Jochum, J.; Jollet, C.; Kaether, F.; Kalousis, L. N.; Kamyshkov, Y.; Kaneda, M.; Kaplan, D. M.; Kawasaki, T.; Kemp, E.; Kryn, D.; Kuze, M.; Lachenmaier, T.; Lane, C. E.; Lasserre, T.; Letourneau, A.; Lhuillier, D.; Lima, H. P., Jr.; Lindner, M.; López-Castaño, J. M.; LoSecco, J. M.; Lubsandorzhiev, B.; Lucht, S.; Maeda, J.; Mariani, C.; Maricic, J.; Martino, J.; Matsubara, T.; Mention, G.; Meregaglia, A.; Miletic, T.; Minotti, A.; Nagasaka, Y.; Navas-Nicolás, D.; Novella, P.; Nunokawa, H.; Obolensky, M.; Onillon, A.; Osborn, A.; Palomares, C.; Pepe, I. M.; Perasso, S.; Porta, A.; Pronost, G.; Reichenbacher, J.; Reinhold, B.; Röhling, M.; Roncin, R.; Rybolt, B.; Sakamoto, Y.; Santorelli, R.; Schilithz, A. C.; Schönert, S.; Schoppmann, S.; Shaevitz, M. H.; Sharankova, R.; Shrestha, D.; Sibille, V.; Sinev, V.; Skorokhvatov, M.; Smith, E.; Soiron, M.; Spitz, J.; Stahl, A.; Stancu, I.; Stokes, L. F. F.; Strait, M.; Suekane, F.; Sukhotin, S.; Sumiyoshi, T.; Sun, Y.; Svoboda, R.; Terao, K.; Tonazzo, A.; Trinh Thi, H. H.; Valdiviesso, G.; Vassilopoulos, N.; Verdugo, A.; Veyssiere, C.; Vivier, M.; von Feilitzsch, F.; Wagner, S.; Walsh, N.; Watanabe, H.; Wiebusch, C.; Wurm, M.; Yang, G.; Yermia, F.; Zimmer, V.

    2016-08-01

    During the commissioning of the first of the two detectors of the Double Chooz experiment, an unexpected and dominant background caused by the emission of light inside the optical volume has been observed. A specific study of the ensemble of phenomena called Light Noise has been carried out in-situ, and in an external laboratory, in order to characterize the signals and to identify the possible processes underlying the effect. Some mechanisms of instrumental noise originating from the PMTs were identified and it has been found that the leading one arises from the light emission localized on the photomultiplier base and produced by the combined effect of heat and high voltage across the transparent epoxy resin covering the electric components. The correlation of the rate and the amplitude of the signal with the temperature has been observed. For the first detector in operation the induced background has been mitigated using online and offline analysis selections based on timing and light pattern of the signals, while a modification of the photomultiplier assembly has been implemented for the second detector in order to blacken the PMT bases.

  20. CORRELATION OF HARD X-RAY AND WHITE LIGHT EMISSION IN SOLAR FLARES

    Energy Technology Data Exchange (ETDEWEB)

    Kuhar, Matej; Krucker, Säm; Battaglia, Marina; Kleint, Lucia; Casadei, Diego [University of Applied Sciences and Arts Northwestern Switzerland, Bahnhofstrasse 6, 5210 Windisch (Switzerland); Oliveros, Juan Carlos Martinez; Hudson, Hugh S. [Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)

    2016-01-01

    A statistical study of the correlation between hard X-ray and white light emission in solar flares is performed in order to search for a link between flare-accelerated electrons and white light formation. We analyze 43 flares spanning GOES classes M and X using observations from the Reuven Ramaty High Energy Solar Spectroscopic Imager and Helioseismic and Magnetic Imager. We calculate X-ray fluxes at 30 keV and white light fluxes at 6173 Å summed over the hard X-ray flare ribbons with an integration time of 45 s around the peak hard-X ray time. We find a good correlation between hard X-ray fluxes and excess white light fluxes, with a highest correlation coefficient of 0.68 for photons with energy of 30 keV. Assuming the thick target model, a similar correlation is found between the deposited power by flare-accelerated electrons and the white light fluxes. The correlation coefficient is found to be largest for energy deposition by electrons above ∼50 keV. At higher electron energies the correlation decreases gradually while a rapid decrease is seen if the energy provided by low-energy electrons is added. This suggests that flare-accelerated electrons of energy ∼50 keV are the main source for white light production.

  1. Oxygenated palm biodiesel: Ignition, combustion and emissions quantification in a light-duty diesel engine

    International Nuclear Information System (INIS)

    Chong, Cheng Tung; Ng, Jo-Han; Ahmad, Solehin; Rajoo, Srithar

    2015-01-01

    Highlights: • Diesel engine test using palm biodiesel and diesel at varying speed and load. • Palm biodiesel shows better performance at late stage of cycle evolution. • Oxygen in palm biodiesel fuel improves local combustion at late stage of combustion. • Emissions of NO are lower at low and medium operating speed for palm biodiesel. • Formulation of trend guide for performance and emissions characteristics for light-duty diesel engines. - Abstract: This paper presents an investigation of oxygenated neat palm biodiesel in a direct injection single cylinder diesel engine in terms of ignition, combustion and emissions characteristics. Conventional non-oxygenated diesel fuel is compared as baseline. The engine testing is performed between the operating speed of 2000–3000 rpm and load of up to 3 bar of brake mean effective pressure. From it, a total of 50 experiment cases are tested to form a comprehensive operational speed-load contour map for ignition and combustion; while various engine-out emissions such as NO, CO, UHCs and CO 2 are compared based on fuel type-speed combinations. The ignition and combustion evolution contour maps quantify the absolute ignition delay period and elucidate the difference between that of palm biodiesel and fossil diesel. Although diesel has shorter ignition delay period by up to 0.6 CAD at 3000 rpm and burns more rapidly at the start of combustion, combustion of palm biodiesel accelerates during the mid-combustion phase and overtakes diesel in the cumulative heat release rates (HRR) prior to the 90% cumulative HRR. This can be attributed to the oxygen contained in palm biodiesel assisting in localized regions of combustion. In terms of performance, the oxygenated nature of palm biodiesel provided mixed performances with improved thermal efficiency and increased brake specific fuel consumption, due to the improved combustion and lower calorific values, respectively. Emission measurements show that NO for palm biodiesel is

  2. Methods of characterizing the distribution of exhaust emissions from light-duty, gasoline-powered motor vehicles in the U.S. fleet.

    Science.gov (United States)

    Fulper, Carl R; Kishan, Sandeep; Baldauf, Richard W; Sabisch, Michael; Warila, Jim; Fujit, Eric M; Scarbro, Carl; Crews, William S; Snow, Richard; Gabele, Peter; Santos, Robert; Tierney, Eugene; Cantrell, Bruce

    2010-11-01

    Mobile sources significantly contribute to ambient concentrations of airborne particulate matter (PM). Source apportionment studies for PM10 (PM fleet to provide data for PM inventory and emissions modeling. The vehicle recruitment design produced a sample that could represent the regional fleet, and by extension, the national fleet. All vehicles were recruited from a stratified sample on the basis of vehicle class (car, truck) and model-year group. The pool of available vehicles was drawn primarily from a sample of vehicle owners designed to represent the selected demographic and geographic characteristics of the Kansas City population. Emissions testing utilized a portable, light-duty chassis dynamometer with vehicles tested using the LA-92 driving cycle, on-board emissions measurement systems, and remote sensing devices. Particulate mass emissions were the focus of the study, with continuous and integrated samples collected. In addition, sample analyses included criteria gases (carbon monoxide, carbon dioxide, nitric oxide/nitrogen dioxide, hydrocarbons), air toxics (speciated volatile organic compounds), and PM constituents (elemental/organic carbon, metals, semi-volatile organic compounds). Results indicated that PM emissions from the in-use fleet varied by up to 3 orders of magnitude, with emissions generally increasing for older model-year vehicles. The study also identified a strong influence of ambient temperature on vehicle PM mass emissions, with rates increasing with decreasing temperatures.

  3. Efficient polymer white-light-emitting diodes with a single-emission layer of fluorescent polymer blend

    International Nuclear Information System (INIS)

    Niu Qiaoli; Xu Yunhua; Jiang Jiaxing; Peng Junbiao; Cao Yong

    2007-01-01

    Efficient polymer white-light-emitting diodes (WPLEDs) have been fabricated with a single layer of fluorescent polymer blend. The device structure consists of ITO/PEDOT/PVK/emissive layer/Ba/Al. The emissive layer is a blend of poly(9,9-dioctylfluorene) (PFO), phenyl-substituted PPV derivative (P-PPV) and a copolymer of 9,9-dioctylfluorene and 4,7-di(4-hexylthien-2-yl)-2,1,3-benzothiadiazole (PFO-DHTBT), which, respectively, emits blue, green and red light. The emission of pure and efficient white light was implemented by tuning the blend weight ratio of PFO: P-PPV: PFO-DHTBT to 96:4:0.4. The maximum current efficiency and luminance are, respectively, 7.6 cd/A at 6.7 V and 11930 cd/m 2 at 11.2 V. The CIE coordinates of white-light emission were stable with the drive voltages

  4. Light vehicle energy efficiency programs and their impact on Brazilian CO2 emissions

    International Nuclear Information System (INIS)

    Wills, William; La Rovere, Emilio Lebre

    2010-01-01

    This paper analyses the impact of an energy efficiency program for light vehicles in Brazil on emissions of carbon dioxide (CO 2 ), the main greenhouse gas in the atmosphere. Several energy efficiency programs for light vehicles around the world are reviewed. The cases of Japan and Europe were selected for presentation here given their status as current and future world leaders in the control of passenger vehicle fuel consumption. The launching of the National Climate Change Plan and the pressure on the Brazilian car industry due to the world financial crisis make it a good time for the Brazilian government to implement such a program, and its various benefits are highlighted in this study. Three scenarios are established for Brazil covering the 2000-2030 period: the first with no efficiency goals, the second with the Japanese goals applied with a 10 years delay, and the third, with the Japanese goals applied with no delay. The consequences of a vehicular efficiency program and its middle and long-term effects on the consumption of energy and the CO 2 emissions are quantified and discussed. The simulation results indicate that efficiency goals may make an important contribution to reducing vehicular emissions and fuel consumption in Brazil, compared to a baseline scenario.

  5. Evidence for Cocoon Emission from the Early Light Curve of SSS17a

    Science.gov (United States)

    Piro, Anthony L.; Kollmeier, Juna A.

    2018-03-01

    Swope Supernova Survey 2017a (SSS17a) was discovered as the first optical counterpart to the gravitational wave event GW170817. Although its light curve on the timescale of weeks roughly matches the expected luminosity and red color of an r-process powered transient, the explanation for the blue emission from high velocity material over the first few days is not as clear. Here we show that the power-law evolution of the luminosity, temperature, and photospheric radius during these early times can be explained by cooling of shock-heated material around the neutron star merger. This heating is likely from the interaction of the gamma-ray burst jet with merger debris, the so-called cocoon emission. We summarize the properties of this emission and provide formulae that can be used to study future detections of shock cooling from merging neutron stars. This argues that optical transient surveys should search for such early, blue light if they wish to find off-axis gamma-ray bursts and double neutron star gravitational wave events as soon as possible after the merger.

  6. Tunable colors and white-light emission based on a microporous luminescent Zn(II)-MOF.

    Science.gov (United States)

    He, Hongming; Sun, Fuxing; Borjigin, Tsolmon; Zhao, Nian; Zhu, Guangshan

    2014-03-07

    Metal-organic frameworks (MOFs) are a rapidly growing class of hybrid materials with many multifunctional properties. The permanent porosity plays a central role in the functional properties. In particular, the luminescent MOFs with a permanent porosity have wide applications in guest species recognition and adsorption. In this contribution, we aim to develop tunable colors and white-light luminescence materials by the encapsulation of Ln(3+) species in microporous luminescent MOFs. A semi-rigid trivalent carboxylic acid 1,3,5-tri(4-carboxyphenoxy)benzene (H3TCPB) was selected as the organic building block, not only because it is suitable to construct microporous frameworks, but also by reason of its blue luminescent emission. Under solvothermal reactions, a microporous MOF material, [Zn3(TCPB)2(H2O)2]·2H2O·4DMF (JUC-113, JUC = Jilin University, China), was synthesized, which has a permanent porosity and emits blue light. According to three-primary colors, the guest luminescent species should be Tb(3+) and Eu(3+) owing to their distinctive colors (Tb(3+), green; Eu(3+), red). In addition, the luminescent properties of JUC-113 can be easily tuned by different combinations of the encapsulation amount of Tb(3+) and Eu(3+), obtaining white-light emission materials.

  7. Support for the revision of regulation on CO2 emissions from light commercial vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Smokers, R.; Fraga, F.; Verbeek, M.; Willems, F.; Massink, R.; Spreen, J. [TNO, Delft (Netherlands); Norris, J.; Martinez, C. [AEA Technology plc, London (United Kingdom); Kampman, B.; Brinke, L.; Van Essen, H. [CE Delft, Delft (Netherlands); Schilling, S.; Gruhlke, A.; Sander, K. [Institut fuer Oekologie und Politik Oekopol, Hamburg (Netherlands); Breemersch, T.; De Ceuster, G.; Vanherle, K.; Heyndrickx, C. [Transport and Mobility Leuven TML, Leuven (Belgium); Wrigley, S.; O' Brien, S.; Johnson, A. [Ricardo UK, Shoreham-by-Sea, West Sussex (United Kingdom); Buttigieg, D.; Sima, L.; Pagnac, J.; Dhaene, G. [IHS Global Insight, Nijmegen (Netherlands)

    2012-04-15

    Road vehicles make a major contribution to transport sector CO2 emissions and the European Union has several policies in place to reduce their emissions. One of these is the regulation to reduce the CO2 emissions of light commercial vehicles (LCVs or vans), Regulation (EU) 510/2011, often referred to as the vans regulation. This contains a number of review clauses, which require the European Commission to carry out an impact assessment on the 2020 target of 147 gCO2/km, and to assess a number of further issues. The ensuing study addresses a wide range of topics relating to this regulation, and includes the development of cost curves for different LCV segments, the evaluation of different utility parameters, a comparison with the effort needed to reduce the CO2 emissions of passenger cars, an assessment of the impact of electric vehicle penetration and calculation of the effects on the total cost of ownership and the societal abatement costs associated with the 2020 target. CE Delft contributed to this study by developing scenarios for the market uptake of electric vehicles in this vehicle segment, and by providing support to the Commission regarding the economic aspects of the Impact Analysis.

  8. Diel Variation of Biogenic Volatile Organic Compound Emissions- A field Study in the Sub, Low and High Arctic on the Effect of Temperature and Light

    Science.gov (United States)

    Lindwall, Frida; Faubert, Patrick; Rinnan, Riikka

    2015-01-01

    Many hours of sunlight in the midnight sun period suggest that significant amounts of biogenic volatile organic compounds (BVOCs) may be released from arctic ecosystems during night-time. However, the emissions from these ecosystems are rarely studied and limited to point measurements during daytime. We measured BVOC emissions during 24-hour periods in the field using a push-pull chamber technique and collection of volatiles in adsorbent cartridges followed by analysis with gas chromatography- mass spectrometry. Five different arctic vegetation communities were examined: high arctic heaths dominated by Salix arctica and Cassiope tetragona, low arctic heaths dominated by Salix glauca and Betula nana and a subarctic peatland dominated by the moss Warnstorfia exannulata and the sedge Eriophorum russeolum. We also addressed how climate warming affects the 24-hour emission and how the daytime emissions respond to sudden darkness. The emissions from the high arctic sites were lowest and had a strong diel variation with almost no emissions during night-time. The low arctic sites as well as the subarctic site had a more stable release of BVOCs during the 24-hour period with night-time emissions in the same range as those during the day. These results warn against overlooking the night period when considering arctic emissions. During the day, the quantity of BVOCs and the number of different compounds emitted was higher under ambient light than in darkness. The monoterpenes α-fenchene, α -phellandrene, 3-carene and α-terpinene as well as isoprene were absent in dark measurements during the day. Warming by open top chambers increased the emission rates both in the high and low arctic sites, forewarning higher emissions in a future warmer climate in the Arctic. PMID:25897519

  9. Diel Variation of Biogenic Volatile Organic Compound Emissions--A field Study in the Sub, Low and High Arctic on the Effect of Temperature and Light.

    Science.gov (United States)

    Lindwall, Frida; Faubert, Patrick; Rinnan, Riikka

    2015-01-01

    Many hours of sunlight in the midnight sun period suggest that significant amounts of biogenic volatile organic compounds (BVOCs) may be released from arctic ecosystems during night-time. However, the emissions from these ecosystems are rarely studied and limited to point measurements during daytime. We measured BVOC emissions during 24-hour periods in the field using a push-pull chamber technique and collection of volatiles in adsorbent cartridges followed by analysis with gas chromatography-mass spectrometry. Five different arctic vegetation communities were examined: high arctic heaths dominated by Salix arctica and Cassiope tetragona, low arctic heaths dominated by Salix glauca and Betula nana and a subarctic peatland dominated by the moss Warnstorfia exannulata and the sedge Eriophorum russeolum. We also addressed how climate warming affects the 24-hour emission and how the daytime emissions respond to sudden darkness. The emissions from the high arctic sites were lowest and had a strong diel variation with almost no emissions during night-time. The low arctic sites as well as the subarctic site had a more stable release of BVOCs during the 24-hour period with night-time emissions in the same range as those during the day. These results warn against overlooking the night period when considering arctic emissions. During the day, the quantity of BVOCs and the number of different compounds emitted was higher under ambient light than in darkness. The monoterpenes α-fenchene, α-phellandrene, 3-carene and α-terpinene as well as isoprene were absent in dark measurements during the day. Warming by open top chambers increased the emission rates both in the high and low arctic sites, forewarning higher emissions in a future warmer climate in the Arctic.

  10. Laser-induced photo emission detection: data acquisition based on light intensity counting

    Science.gov (United States)

    Yulianto, N.; Yudasari, N.; Putri, K. Y.

    2017-04-01

    Laser Induced Breakdown Detection (LIBD) is one of the quantification techniques for colloids. There are two ways of detection in LIBD: optical detection and acoustic detection. LIBD is based on the detection of plasma emission due to the interaction between particle and laser beam. In this research, the changing of light intensity during plasma formations was detected by a photodiode sensor. A photo emission data acquisition system was built to collect and transform them into digital counts. The real-time system used data acquisition device National Instrument DAQ 6009 and LABVIEW software. The system has been tested on distilled water and tap water samples. The result showed 99.8% accuracy by using counting technique in comparison to the acoustic detection with sample rate of 10 Hz, thus the acquisition system can be applied as an alternative method to the existing LIBD acquisition system.

  11. Phosphorescent Molecularly Doped Light-Emitting Diodes with Blended Polymer Host and Wide Emission Spectra

    Directory of Open Access Journals (Sweden)

    Jun Wang

    2013-01-01

    Full Text Available Stable green light emission and high efficiency organic devices with three polymer layers were fabricated using bis[2-(4′-tert-butylphenyl-1-phenyl-1H-benzoimidazole-N,C2′] iridium(III (acetylacetonate doped in blended host materials. The 1 wt% doping concentration showed maximum luminance of 7841 cd/cm2 at 25.6 V and maximum current efficiency of 9.95 cd/A at 17.2 V. The electroluminescence spectra of devices indicated two main peaks at 522 nm and 554 nm coming from phosphor dye and a full width at half maximum (FWHM of 116 nm. The characteristics of using blended host, doping iridium complex, emission spectrum, and power efficiency of organic devices were investigated.

  12. Short term changes in methanol emission and pectin methylesterase activity are not directly affected by light in Lycopersicon esculentum

    Directory of Open Access Journals (Sweden)

    M. T. Lerdau

    2011-04-01

    Full Text Available Plants are an important source of atmospheric methanol (MeOH, the second most abundant organic gas after methane. Factors regulating phytogenic MeOH production are not well constrained in current MeOH emission models. Previous studies have indicated that light may have a direct influence on MeOH production. As light is known to regulate cell wall expansion, it was predicted that light would stimulate MeOH production through the pectin methylesterase (PME pathway. MeOH emissions normalized for stomatal conductance (gs did not, however, increase with light over short time scales (20–30 min. After experimentally controlling for gs and temperature, no light activation of PME activity or MeOH emission was observed. The results clearly demonstrate that light does not directly influence short-term changes in MeOH production and emission. Our data suggest that substrate limitation may be important in regulating MeOH production over short time scales. Future investigation of the long-term impacts of light on MeOH production may increase understanding of MeOH emission dynamics at the seasonal time scale.

  13. Efficient organic light-emitting devices with platinum-complex emissive layer

    KAUST Repository

    Yang, Xiaohui

    2011-01-18

    We report efficient organic light-emitting devices having a platinum-complex emissive layer with the peak external quantum efficiency of 17.5% and power efficiency of 45 lm W−1. Variation in the device performance with platinum-complex layer thickness can be attributed to the interplay between carrier recombination and intermolecular interactions in the layer. Efficient white devices using double platinum-complex layers show the external quantum efficiency of 10%, the Commission Internationale d’Énclairage coordinates of (0.42, 0.41), and color rendering index of 84 at 1000 cd m−2.

  14. A modal approach to light emission and propagation in coupled cavity waveguide systems

    DEFF Research Database (Denmark)

    Gregersen, Niels; Kristensen, P. T.; de Lasson, Jakob Rosenkrantz

    2016-01-01

    We theoretically investigate systems of optical cavities coupled to waveguides,which necessitates the introduction of non-trivial radiation conditions and normalization procedures. In return, the approach provides simple and accurate modeling of Green functions,Purcell factors and perturbation...... corrections, as well as an alternative approach to the so-calledcoupled mode theory. In combination, these results may form part of the foundations for highly efficient, yet physically transparent models of light emission and propagation in both classical and quantum integrated photonic circuits....

  15. Investigation on surface-plasmon-enhanced light emission of InGaN/GaN multiple quantum wells

    Science.gov (United States)

    Yu, Zhenzhong; Li, Qiang; Fan, Qigao; Zhu, Yixin

    2018-05-01

    We demonstrate surface-plasmon (SP) enhanced light emission from InGaN/GaN near ultraviolet (NUV) multiple quantum wells (MQWs) using Ag thin films and nano-particles (NPs). Two types of Ag NP arrays are fabricated on the NUV-MQWs, one is fabricated on p-GaN layer with three different sizes of about 120, 160 and 240 nm formed by self-assembled process, while the other is embedded close to the MQWs. In addition, the influence of the surface plasmon polariton (SPP) and localized surface plasmon (LSP) in NUV-MQWs has been investigated by photoluminescence (PL) measurement. Both PL measurements and theoretical simulation results show that the NUV light would be extracted more effectively under LSP mode than that of SPP mode. The highest enhancement of PL intensity is increased by 324% for the sample with NPs embedded in etched p-GaN near the MQWs as compared with the bare MQWs, also is about 1.24 times higher than the MQW sample covered with Ag NPs on the surface, indicating strong surface scattering and SP coupling between Ag NPs and NUV-MQWs.

  16. Detection of Time Lags between Quasar Continuum Emission Bands Based On Pan-STARRS Light Curves

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Yan-Fei [Kavli Institute for Theoretical Physics, University of California, Santa Barbara, CA 93106 (United States); Green, Paul J.; Pancoast, Anna; MacLeod, Chelsea L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Morganson, Eric; Shen, Yue [Department of Astronomy, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Anderson, Scott F.; Ruan, John J. [Department of Astronomy, University of Washington, Box 351580, Seattle, WA 98195 (United States); Brandt, W. N.; Grier, C. J. [Department of Astronomy and Astrophysics, The Pennsylvania State University, University Park, PA 16802 (United States); Rix, H.-W. [Max Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany); Protopapas, Pavlos [Institute for Applied Computational Science, John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138 (United States); Scott, Caroline [Astrophysics, Imperial College London, Blackett Laboratory, London SW7 2AZ (United Kingdom); Burgett, W. S.; Hodapp, K. W.; Huber, M. E.; Kaiser, N.; Kudritzki, R. P.; Magnier, E. A. [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu HI 96822 (United States); and others

    2017-02-20

    We study the time lags between the continuum emission of quasars at different wavelengths, based on more than four years of multi-band ( g , r , i , z ) light curves in the Pan-STARRS Medium Deep Fields. As photons from different bands emerge from different radial ranges in the accretion disk, the lags constrain the sizes of the accretion disks. We select 240 quasars with redshifts of z ≈ 1 or z ≈ 0.3 that are relatively emission-line free. The light curves are sampled from day to month timescales, which makes it possible to detect lags on the scale of the light crossing time of the accretion disks. With the code JAVELIN , we detect typical lags of several days in the rest frame between the g band and the riz bands. The detected lags are ∼2–3 times larger than the light crossing time estimated from the standard thin disk model, consistent with the recently measured lag in NGC 5548 and microlensing measurements of quasars. The lags in our sample are found to increase with increasing luminosity. Furthermore, the increase in lags going from g − r to g − i and then to g − z is slower than predicted in the thin disk model, particularly for high-luminosity quasars. The radial temperature profile in the disk must be different from what is assumed. We also find evidence that the lags decrease with increasing line ratios between ultraviolet Fe ii lines and Mg ii, which may point to changes in the accretion disk structure at higher metallicity.

  17. Solid state white light emission studies of erbium and dysprosium doped halide crystals

    Science.gov (United States)

    Culp, Mical L.

    Rare-earth ions account for fourteen in number within the lanthanide series; with erbium and dysprosium being primary candidates in many applications such as spectroscopy, amplifiers, and, most recently, white light emission. Both erbium and dysprosium occupy Ca sites in the material. CaF2 is a divalent compound, and both erbium and dysprosium enter the lattice in a triply ionized state because they form trivalent compounds defects that occur in the material because a trivalent dopant ion replaces a divalent host ion. The absorption and emission peaks are identified within Er3+ and Dy3+ spectral transitions. The sample color appears to be white in Er3+ doped CaF2 or white under near-infrared laser excitation. Under 405nm laser excitation investigation, these materials exhibited a bright white fluorescence or emission color that was found to be dependent on the pump laser wavelength used as well as laser power. Excitation spectral recordings were made by tuning the pump laser wavelength and focusing the sample. The sample emission appears to be white under near-infrared excitation as well as violet laser excitation. Excited state lifetimes were measured to analyze the data. Our studies indicate that these samples could be useful in solid-state lighting applications. The energy levels of Dy3+ are the same as those of Er3+ except for the orders of the arrangements. Quenching is a major problem in Dy3+ materials, and serves to be the primary reason for why this material is unpopular in laser development. We selected Dy3+ - doped low phonon material such as CaF2, KPb2Cl5 and KPb2Br 5 for investigations. Under 405nm excitation, all these materials emitted white luminescence. Emission occurred in CaF2 from the ground state to the excited state levels containing 4F9/2. In KPb2Br5 emission occurred from 4F 9/2, 4G11/2, and 4M1/2 due to small phonon frequency.

  18. Emission factors and light absorption properties of brown carbon from household coal combustion in China

    Science.gov (United States)

    Sun, Jianzhong; Zhi, Guorui; Hitzenberger, Regina; Chen, Yingjun; Tian, Chongguo; Zhang, Yayun; Feng, Yanli; Cheng, Miaomiao; Zhang, Yuzhe; Cai, Jing; Chen, Feng; Qiu, Yiqin; Jiang, Zhiming; Li, Jun; Zhang, Gan; Mo, Yangzhi

    2017-04-01

    Brown carbon (BrC) draws increasing attention due to its effects on climate and other environmental factors. In China, household coal burned for heating and cooking purposes releases huge amounts of carbonaceous particles every year; however, BrC emissions have rarely been estimated in a persuasive manner due to the unavailable emission characteristics. Here, seven coals jointly covering geological maturity from low to high were burned in four typical stoves as both chunk and briquette styles. The optical integrating sphere (IS) method was applied to measure the emission factors (EFs) of BrC and black carbon (BC) via an iterative process using the different spectral dependence of light absorption for BrC and BC and using humic acid sodium salt (HASS) and carbon black (CarB) as reference materials. The following results have been found: (i) the average EFs of BrC for anthracite coal chunks and briquettes are 1.08 ± 0.80 and 1.52 ± 0.16 g kg-1, respectively, and those for bituminous coal chunks and briquettes are 8.59 ± 2.70 and 4.01 ± 2.19 g kg-1, respectively, reflecting a more significant decline in BrC EFs for bituminous coals than for anthracites due to briquetting. (ii) The BrC EF peaks at the middle of coal's geological maturity, displaying a bell-shaped curve between EF and volatile matter (Vdaf). (iii) The calculated BrC emissions from China's residential coal burning amounted to 592 Gg (1 Gg = 109 g) in 2013, which is nearly half of China's total BC emissions. (iv) The absorption Ångström exponents (AAEs) of all coal briquettes are higher than those of coal chunks, indicating that the measure of coal briquetting increases the BrC / BC emission ratio and thus offsets some of the climate cooling effect of briquetting. (v) In the scenario of current household coal burning in China, solar light absorption by BrC (350-850 nm in this study) accounts for more than a quarter (0.265) of the total absorption. This implies the significance of BrC to climate

  19. Spatial variability of nitrous oxide and methane emissions from an MBT landfill in operation: Strong N{sub 2}O hotspots at the working face

    Energy Technology Data Exchange (ETDEWEB)

    Harborth, Peter, E-mail: p.harborth@tu-bs.de [Department of Waste and Resource Management, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, Braunschweig (Germany); Fuß, Roland [Institute of Climate-Smart Agriculture, Johann Heinrich von Thünen Institute, Braunschweig (Germany); Münnich, Kai [Department of Waste and Resource Management, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, Braunschweig (Germany); Flessa, Heinz [Institute of Climate-Smart Agriculture, Johann Heinrich von Thünen Institute, Braunschweig (Germany); Fricke, Klaus [Department of Waste and Resource Management, Leichtweiß-Institute for Hydraulic Engineering and Water Resources, Technische Universität Braunschweig, Braunschweig (Germany)

    2013-10-15

    Highlights: ► First measurements of N{sub 2}O and CH{sub 4} emissions from an MBT landfill. ► High N{sub 2}O emissions from recently deposited material. ► N{sub 2}O emissions associated with aeration and the occurrence of nitrite and nitrate. ► Strong negative correlation between CH{sub 4} and N{sub 2}O production activity. - Abstract: Mechanical biological treatment (MBT) is an effective technique, which removes organic carbon from municipal solid waste (MSW) prior to deposition. Thereby, methane (CH{sub 4}) production in the landfill is strongly mitigated. However, direct measurements of greenhouse gas emissions from full-scale MBT landfills have not been conducted so far. Thus, CH{sub 4} and nitrous oxide (N{sub 2}O) emissions from a German MBT landfill in operation as well as their concentrations in the landfill gas (LFG) were measured. High N{sub 2}O emissions of 20–200 g CO{sub 2} eq. m{sup −2} h{sup −1} magnitude (up to 428 mg N m{sup −2} h{sup −1}) were observed within 20 m of the working face. CH{sub 4} emissions were highest at the landfill zone located at a distance of 30–40 m from the working face, where they reached about 10 g CO{sub 2} eq. m{sup −2} h{sup −1}. The MBT material in this area has been deposited several weeks earlier. Maximum LFG concentration for N{sub 2}O was 24.000 ppmv in material below the emission hotspot. At a depth of 50 cm from the landfill surface a strong negative correlation between N{sub 2}O and CH{sub 4} concentrations was observed. From this and from the distribution pattern of extractable ammonium, nitrite, and nitrate it has been concluded that strong N{sub 2}O production is associated with nitrification activity and the occurrence of nitrite and nitrate, which is initiated by oxygen input during waste deposition. Therefore, CH{sub 4} mitigation measures, which often employ aeration, could result in a net increase of GHG emissions due to increased N{sub 2}O emissions, especially at MBT landfills.

  20. Selective area growth and characterization of InGaN nanocolumns for phosphor-free white light emission

    Energy Technology Data Exchange (ETDEWEB)

    Albert, S.; Bengoechea-Encabo, A.; Sanchez-Garcia, M. A.; Calleja, E. [ISOM and Dept. Ingenieria Electronica, ETSI Telecomunicacion, Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Jahn, U. [Paul-Drude-Institut fuer Festkoeperelektronik, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2013-03-21

    This work reports on the morphology and light emission characteristics of ordered InGaN nanocolumns grown by plasma-assisted molecular beam epitaxy. Within the growth temperature range of 750 to 650 Degree-Sign C, the In incorporation can be modified either by the growth temperature, the In/Ga ratio, or the III/V ratio, following different mechanisms. Control of these factors allows the optimization of the InGaN nanocolumns light emission wavelength and line-shape. Furthermore, yellow-white emission is obtained at room temperature from nanostructures with a composition-graded active InGaN region obtained by temperature gradients during growth.

  1. Dissolved organic carbon and nitrogen mineralization strongly affect co2 emissions following lime application to acidic soil

    International Nuclear Information System (INIS)

    Shaaban, M.; Peng, Q.; Lin, S.; Wu, Y.

    2014-01-01

    Emission of greenhouse gases from agricultural soils has main contribution to the climatic change and global warming. Dynamics of dissolved organic carbon (DOC) and nitrogen mineralization can affect CO/sub 2/ emission from soils. Influence of DOC and nitrogen mineralization on CO/sub 2/ emissions following lime application to acidic soil was investigated in current study. Laboratory experiment was conducted under aerobic conditions with 25% moisture contents (66% water-filled pore space) at 25 degree C in the dark conditions. Different treatments of lime were applied to acidic soil as follows: CK (control), L (low rate of lime: 0.2g lime / 100 g soil) and H (high rate of lime: 0.5g lime /100g soil). CO/sub 2/ emissions were measured by gas chromatography and dissolved organic carbon, NH4 +-N, NO/sub 3/ --N and soil pH were measured during incubation study. Addition of lime to acidic soil significantly increased the concentration of DOC and N mineralization rate. Higher concentrations of DOC and N mineralization, consequently, increased the CO/sub 2/ emissions from lime treated soils. Cumulative CO/sub 2/ emission was 75% and 71% higher from L and H treatments as compared to CK. The results of current study suggest that DOC and N mineralization are critical in controlling gaseous emissions of CO/sub 2/ from acidic soils following lime application. (author)

  2. Strong red-emission of Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12} powders for phosphor applications

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yan [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Jiménez, José A. [Department of Chemistry, University of North Florida, Jacksonville, FL 32224 (United States); Wu, Yiquan, E-mail: wuy@alfred.edu [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States)

    2016-08-15

    The synthesis and photoluminescence properties of trivalent europium doped lithium titanate (Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12}) with different Eu{sup 3+} concentrations (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) are reported and analyzed as a phosphor. Europium (III) nitrate (Eu(NO{sub 3}){sub 3}) was employed as Eu{sup 3+} source, while lithium acetate dihydrate (CH{sub 3}COOLi·2H{sub 2}O) and titanium n-butoxide (Ti(OC{sub 4}H{sub 9}){sub 4}) were adopted as raw materials to synthesize the host lithium titanate with a Li:Ti stoichiometry of 4.5:1. Phase identification was performed using X-ray diffraction (XRD), and morphology was examined using scanning electron microscopy (SEM). Eu{sup 3+}:Li{sub 4}Ti{sub 5}O{sub 12} powders showed strong red emission at 612 nm, corresponding to the {sup 5}D{sub 0}–{sup 7}F{sub 2} transition, with the strongest excitation peak observed in the blue light region at 464 nm. Decay time analyses revealed relatively short lifetimes accompanying typical exponential decay rates. The effect of Eu{sup 3+} concentration (0.1 mol%, 0.3 mol%, 1.0 mol%, 3.0 mol%) on photoluminescence intensity and decay time was explored, and is reported here. It was determined that the CIE color coordinates (0.66, 0.34) of the doped Li{sub 4}Ti{sub 5}O{sub 12} powders were independent of Eu{sup 3+} concentration, and that the coordinates are very similar to the ideal red chromaticity (0.67, 0.33) designated by the National Television Standard Committee (NTSC) system.

  3. Strong soft X-ray emission from a double-stream gas puff target irradiated with a nanosecond Nd:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Fiedorowicz, H.; Bartnik, A.; Rakowski, R.; Szczurek, M. [Military Univ. of Technology, Warsaw (Poland). Inst. of Optoelectronics; Daido, H.; Suzuki, M.; Yamagami, S.; Choi, I.W.; Tang, H.J. [Osaka Univ., Suita (Japan). Inst. of Laser Engineering

    2001-07-01

    Soft X-ray emission from a new double-stream gas puff target irradiated with a nanosecond, high-power Nd:YAG laser pulse has been studied. The target was formed by pulsed injection of gas into a hollow gas stream made from helium by using a double-nozzle setup. Strong X-ray emissions near 10 nm from the double-stream krypton/helium, near 11 nm from the xenon/helium, and at 13 nm from the oxygen/helium targets were observed. The emission from the double-stream gas puff target was several times higher as compared to the ordinary gas puff targets, and comparable to the emission from the solid targets irradiated in the same conditions. (orig.)

  4. Tuning Light Emission of a Pressure-Sensitive Silicon/ZnO Nanowires Heterostructure Matrix through Piezo-phototronic Effects.

    Science.gov (United States)

    Chen, Mengxiao; Pan, Caofeng; Zhang, Taiping; Li, Xiaoyi; Liang, Renrong; Wang, Zhong Lin

    2016-06-28

    Based on white light emission at silicon (Si)/ZnO hetrerojunction, a pressure-sensitive Si/ZnO nanowires heterostructure matrix light emitting diode (LED) array is developed. The light emission intensity of a single heterostructure LED is tuned by external strain: when the applied stress keeps increasing, the emission intensity first increases and then decreases with a maximum value at a compressive strain of 0.15-0.2%. This result is attributed to the piezo-phototronic effect, which can efficiently modulate the LED emission intensity by utilizing the strain-induced piezo-polarization charges. It could tune the energy band diagrams at the junction area and regulate the optoelectronic processes such as charge carriers generation, separation, recombination, and transport. This study achieves tuning silicon based devices through piezo-phototronic effect.

  5. Metal oxide core shell nanostructures as building blocks for efficient light emission (SISGR)

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jane P [Univ. of California, Los Angeles, CA (United States); Dorman, James [Univ. of California, Los Angeles, CA (United States); Cheung, Cyrus [Univ. of California, Los Angeles, CA (United States)

    2016-01-12

    The objective of this research is to synthesize core-shell nano-structured metal oxide materials and investigate their structural, electronic and optical properties to understand the microscopic pathways governing the energy conversion process, thereby controlling and improving their efficiency. Specifically, the goal is to use a single metal oxide core-shell nanostructure and a single excitation source to generate photons with long emission lifetime over the entire visible spectrum and when controlled at the right ratio, generating white light. In order to achieve this goal, we need to control the energy transfer between light emitting elements, which dictates the control of their interatomic spacing and spatial distribution. We developed an economical wet chemical process to form the nanostructured core and to control the thickness and composition of the shell layers. With the help from using DOE funded synchrotron radiation facility, we delineated the growth mechanism of the nano-structured core and the shell layers, thereby enhancing our understanding of structure-property relation in these materials. Using the upconversion luminescence and the lifetime measurements as effective feedback to materials sysnthes is and integration, we demonstrated improved luminescence lifetimes of the core-shell nano-structures and quantified the optimal core-multi-shell structure with optimum shell thickness and composition. We developed a rare-earths co-doped LaPO4 core-multishell structure in order to produce a single white light source. It was decided that the mutli-shell method would produce the largest increase in luminescence efficiency while limiting any energy transfer that may occur between the dopant ions. All samples resulted in emission spectra within the accepted range of white light generation based on the converted CIE color coordinates. The white light obtained varied between warm and cool white depending on the layering architecture, allowing for the

  6. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes.

    Directory of Open Access Journals (Sweden)

    Kirsten Oswald

    Full Text Available Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere.

  7. Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

    Science.gov (United States)

    Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

    2015-01-01

    Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

  8. Influence of heterojunction interface on exciplex emission from organic light-emitting diodes under electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shengyi; Zhang, Xiulong; Lou, Zhidong; Hou, Yanbing [Beijing Jiaotong University, Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing (China)

    2008-03-15

    In this paper, electroluminescence from organic light-emitting diodes based on 2-(4'-biphenyl)-5-(4{sup ''}-tert-butylphenyl)-1,3,4-oxadiazole (PBD) and N,N'-diphenyl-N,N'-bis(3-methylphenyl)-(1,1'-biphenyl)-4,4'-diamine (TPD) is reported. Based on the exciplex emission from the TPD/PBD interface under high electric fields, the influence of the TPD/PBD interface on exciplex emission was investigated by increasing the number of TPD/PBD interfaces while keeping both the total thickness of the TPD layer and the PBD layer constant in the multiple quantum-wells (MQW) device ITO/TPD/[PBD/TPD]{sub n}/PBD/Al (n is the well number that was varied from 0 to 3). Our experimental data shows that exciplex emission can be enhanced by suitably increasing the well number of this kind of MQW-like device. (orig.)

  9. The acclimation of Phaeodactylum tricornutum to blue and red light does not influence the photosynthetic light reaction but strongly disturbs the carbon allocation pattern.

    Directory of Open Access Journals (Sweden)

    Anne Jungandreas

    Full Text Available Diatoms are major contributors to the aquatic primary productivity and show an efficient acclimation ability to changing light intensities. Here, we investigated the acclimation of Phaeodactylum tricornutum to different light quality with respect to growth rate, photosynthesis rate, macromolecular composition and the metabolic profile by shifting the light quality from red light (RL to blue light (BL and vice versa. Our results show that cultures pre-acclimated to BL and RL exhibited similar growth performance, photosynthesis rates and metabolite profiles. However, light shift experiments revealed rapid and severe changes in the metabolite profile within 15 min as the initial reaction of light acclimation. Thus, during the shift from RL to BL, increased concentrations of amino acids and TCA cycle intermediates were observed whereas during the BL to RL shift the levels of amino acids were decreased and intermediates of glycolysis accumulated. Accordingly, on the time scale of hours the RL to BL shift led to a redirection of carbon into the synthesis of proteins, whereas during the BL to RL shift an accumulation of carbohydrates occurred. Thus, a vast metabolic reorganization of the cells was observed as the initial reaction to changes in light quality. The results are discussed with respect to a putative direct regulation of cellular enzymes by light quality and by transcriptional regulation. Interestingly, the short-term changes in the metabolome were accompanied by changes in the degree of reduction of the plastoquinone pool. Surprisingly, the RL to BL shift led to a severe inhibition of growth within the first 48 h which was not observed during the BL to RL shift. Furthermore, during the phase of growth arrest the photosynthetic performance did not change. We propose arguments that the growth arrest could have been caused by the reorganization of intracellular carbon partitioning.

  10. SUPERLUMINOUS SUPERNOVAE POWERED BY MAGNETARS: LATE-TIME LIGHT CURVES AND HARD EMISSION LEAKAGE

    International Nuclear Information System (INIS)

    Wang, S. Q.; Wang, L. J.; Dai, Z. G.; Wu, X. F.

    2015-01-01

    Recently, research performed by two groups has revealed that the magnetar spin-down energy injection model with full energy trapping can explain the early-time light curves of SN 2010gx, SN 2013dg, LSQ12dlf, SSS120810, and CSS121015 but fails to fit the late-time light curves of these superluminous supernovae (SLSNe). These results imply that the original magnetar-powered model is challenged in explaining these SLSNe. Our paper aims to simultaneously explain both the early- and late-time data/upper limits by considering the leakage of hard emissions. We incorporate quantitatively the leakage effect into the original magnetar-powered model and derive a new semianalytical equation. Comparing the light curves reproduced by our revised magnetar-powered model with the observed data and/or upper limits of these five SLSNe, we found that the late-time light curves reproduced by our semianalytical equation are in good agreement with the late-time observed data and/or upper limits of SN 2010gx, CSS121015, SN 2013dg, and LSQ12dlf and the late-time excess of SSS120810, indicating that the magnetar-powered model might be responsible for these SLSNe and that the gamma-ray and X-ray leakages are unavoidable when the hard photons were down-Comptonized to softer photons. To determine the details of the leakage effect and unveil the nature of SLSNe, more high-quality bolometric light curves and spectra of SLSNe are required

  11. Probing Millisecond Pulsar Emission Geometry Using Light Curves From the Fermi Large Area Telescope

    Science.gov (United States)

    Venter, Christo; Harding, Alice; Guillemot, L.

    2009-01-01

    An interesting new high-energy pulsar sub-population is emerging following early discoveries of gamma-ray millisecond pulsars (MSPs) by the Fermi Large Area Telescope (LAT). We present results from 3D emission modeling, including the Special Relativistic effects of aberration and time-of-flight delays and also rotational sweepback of 13-field lines, in the geometric context of polar cap (PC), slot gap (SG), outer gap (OG), and two-pole caustic (TPC) pulsar models. In contrast to the general belief that these very old, rapidly-rotating neutron stars (NSs) should have largely pair-starved magnetospheres due to the absence of significant pair production, we find that most of the light curves are best fit by SG and OG models, which indicates the presence of narrow accelerating gaps limited by robust pair production -- even in these pulsars with very low spin-down luminosities. The gamma-ray pulse shapes and relative phase lags with respect to the radio pulses point to high-altitude emission being dominant for all geometries. We also find exclusive differentiation of the current gamma-ray MSP population into two MSP sub-classes: light curve shapes and lags across wavebands impose either pair-starved PC (PSPC) or SG / OG-type geometries. In the first case, the radio pulse has a small lag with respect to the single gamma-ray pulse, while the (first) gamma-ray peak usually trails the radio by a large phase offset in the latter case. Finally, we find that the flux correction factor as a function of magnetic inclination and observer angles is typically of order unity for all models. Our calculation of light curves and flux correction factor f(_, _, P) for the case of MSPs is therefore complementary to the "ATLAS paper" of Watters et al. for younger pulsars.

  12. Particulate matter from both heavy fuel oil and diesel fuel shipping emissions show strong biological effects on human lung cells at realistic and comparable in vitro exposure conditions.

    Directory of Open Access Journals (Sweden)

    Sebastian Oeder

    Full Text Available Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling.To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols.Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO or cleaner-burning diesel fuel (DF. Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses.The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon ("soot". Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification.Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the use of HFO and DF we recommend a

  13. Particulate Matter from Both Heavy Fuel Oil and Diesel Fuel Shipping Emissions Show Strong Biological Effects on Human Lung Cells at Realistic and Comparable In Vitro Exposure Conditions

    Science.gov (United States)

    Dilger, Marco; Paur, Hanns-Rudolf; Schlager, Christoph; Mülhopt, Sonja; Diabaté, Silvia; Weiss, Carsten; Stengel, Benjamin; Rabe, Rom; Harndorf, Horst; Torvela, Tiina; Jokiniemi, Jorma K.; Hirvonen, Maija-Riitta; Schmidt-Weber, Carsten; Traidl-Hoffmann, Claudia; BéruBé, Kelly A.; Wlodarczyk, Anna J.; Prytherch, Zoë; Michalke, Bernhard; Krebs, Tobias; Prévôt, André S. H.; Kelbg, Michael; Tiggesbäumker, Josef; Karg, Erwin; Jakobi, Gert; Scholtes, Sorana; Schnelle-Kreis, Jürgen; Lintelmann, Jutta; Matuschek, Georg; Sklorz, Martin; Klingbeil, Sophie; Orasche, Jürgen; Richthammer, Patrick; Müller, Laarnie; Elsasser, Michael; Reda, Ahmed; Gröger, Thomas; Weggler, Benedikt; Schwemer, Theo; Czech, Hendryk; Rüger, Christopher P.; Abbaszade, Gülcin; Radischat, Christian; Hiller, Karsten; Buters, Jeroen T. M.; Dittmar, Gunnar; Zimmermann, Ralf

    2015-01-01

    Background Ship engine emissions are important with regard to lung and cardiovascular diseases especially in coastal regions worldwide. Known cellular responses to combustion particles include oxidative stress and inflammatory signalling. Objectives To provide a molecular link between the chemical and physical characteristics of ship emission particles and the cellular responses they elicit and to identify potentially harmful fractions in shipping emission aerosols. Methods Through an air-liquid interface exposure system, we exposed human lung cells under realistic in vitro conditions to exhaust fumes from a ship engine running on either common heavy fuel oil (HFO) or cleaner-burning diesel fuel (DF). Advanced chemical analyses of the exhaust aerosols were combined with transcriptional, proteomic and metabolomic profiling including isotope labelling methods to characterise the lung cell responses. Results The HFO emissions contained high concentrations of toxic compounds such as metals and polycyclic aromatic hydrocarbon, and were higher in particle mass. These compounds were lower in DF emissions, which in turn had higher concentrations of elemental carbon (“soot”). Common cellular reactions included cellular stress responses and endocytosis. Reactions to HFO emissions were dominated by oxidative stress and inflammatory responses, whereas DF emissions induced generally a broader biological response than HFO emissions and affected essential cellular pathways such as energy metabolism, protein synthesis, and chromatin modification. Conclusions Despite a lower content of known toxic compounds, combustion particles from the clean shipping fuel DF influenced several essential pathways of lung cell metabolism more strongly than particles from the unrefined fuel HFO. This might be attributable to a higher soot content in DF. Thus the role of diesel soot, which is a known carcinogen in acute air pollution-induced health effects should be further investigated. For the

  14. Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission

    KAUST Repository

    Quan, Li Na

    2017-05-10

    Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm2, yielding a ratio of quantum yield to excitation intensity of 0.3 cm2/mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m2.

  15. Improvement of Lighting Uniformity and Phosphor Life in Field Emission Lamps Using Carbon Nanocoils

    Directory of Open Access Journals (Sweden)

    Kun-Ju Chung

    2015-01-01

    Full Text Available The lighting performances and phosphor degradation in field emission lamps (FELs with two different kinds of cathode materials—multiwalled carbon nanotubes (MWCNTs and carbon nanocoils (CNCs—were compared. The MWCNTs and CNCs were selectively synthesized on 304 stainless steel wire substrates dip-coated with nanosized Pd catalysts by controlling the growth temperature in thermal chemical vapor deposition, and the film uniformity can be optimized by adjusting the growth time. FELs were successfully fabricated by assembling these cathode filaments with a glass bulb-type anode. The FEL with the CNC cathode showed much higher lighting uniformity and light-spot density and a lower current at the same voltage than that with the MWCNT cathode filament, and its best luminous efficiency was as high as 75 lm/W at 8 kV. We also found that, for P22, the phosphor degradation can be effectively suppressed by replacing MWCNTs with CNCs in the cathode, due to the much larger total bright spot area and hence much lower current density loading on the anode.

  16. Controlling the emission and propagation of light with nano-plasmonic metamaterials and metasurfaces

    Science.gov (United States)

    Ni, Xingjie

    Metamaterials---artificially structured materials with engineered electromagnetic properties---have enabled unprecedented flexibility in manipulating electromagnetic waves and producing new functionalities. Metasurfaces are subwavelength thin metamaterial layers to introduce unusual properties do not exist in nature. They can play a fundamental role in generating synthetic scattering diagrams of macroscopic objects. Optical metamaterials and metasurfaces have enabled unprecedented flexibility in manipulating light waves and producing new functionalities. We have studied various topics in this field, from designs to potential applications. We experimentally demonstrated the world's first optical metasurface which is capable of precisely manipulating light in arbitrary ways over a broad range of near-infrared light, which could make possible of many optical innovations such as more powerful microscopes, telecommunications and computers. We proposed the first hyperbolic metasurface, which consist of a highly anisotropic material layer and an isotropic material layer can support Dyakonov surface waves that have hyperbolic dispersion. This type of metasurfaces support a broadband singularity in the photonic density of states, which opens up another possibility to engineer the spontaneous emission efficiency. We also developed a set of parallel simulation tools which can handle a variety of problems in nanophotonics and plasmonics. Especially, we established an on-line research environment for the research community with six tools, which deliver a cloud computing service with no demand for either any powerful computational hardware or any additional software installations and cover a range of tasks including the design and simulation of complex transformation optics devices and optical metamaterials.

  17. Tailoring the Energy Landscape in Quasi-2D Halide Perovskites Enables Efficient Green-Light Emission.

    Science.gov (United States)

    Quan, Li Na; Zhao, Yongbiao; García de Arquer, F Pelayo; Sabatini, Randy; Walters, Grant; Voznyy, Oleksandr; Comin, Riccardo; Li, Yiying; Fan, James Z; Tan, Hairen; Pan, Jun; Yuan, Mingjian; Bakr, Osman M; Lu, Zhenghong; Kim, Dong Ha; Sargent, Edward H

    2017-06-14

    Organo-metal halide perovskites are a promising platform for optoelectronic applications in view of their excellent charge-transport and bandgap tunability. However, their low photoluminescence quantum efficiencies, especially in low-excitation regimes, limit their efficiency for light emission. Consequently, perovskite light-emitting devices are operated under high injection, a regime under which the materials have so far been unstable. Here we show that, by concentrating photoexcited states into a small subpopulation of radiative domains, one can achieve a high quantum yield, even at low excitation intensities. We tailor the composition of quasi-2D perovskites to direct the energy transfer into the lowest-bandgap minority phase and to do so faster than it is lost to nonradiative centers. The new material exhibits 60% photoluminescence quantum yield at excitation intensities as low as 1.8 mW/cm 2 , yielding a ratio of quantum yield to excitation intensity of 0.3 cm 2 /mW; this represents a decrease of 2 orders of magnitude in the excitation power required to reach high efficiency compared with the best prior reports. Using this strategy, we report light-emitting diodes with external quantum efficiencies of 7.4% and a high luminescence of 8400 cd/m 2 .

  18. Insights into the Silver Reflection Layer of a Vertical LED for Light Emission Optimization.

    Science.gov (United States)

    Khan, Mansoor Ali; Chen, Hansheng; Qu, Jiangtao; Trimby, Patrick W; Moody, Steven; Yao, Yin; Ringer, Simon P; Zheng, Rongkun

    2017-07-19

    In this work, Ag as a highly reflective mirror layer of gallium nitride (GaN)-based blue vertical light-emitting diodes (VLEDs) has been systematically investigated by correlating scanning electron microscopy/energy dispersive X-ray spectroscopy/transmission Kikuchi diffraction/electron backscatter diffraction, aberration-corrected scanning transmission electron microscopy, and atomic force microscopy techniques. In the context of high-efficiency lighting, three critical aspects have been scrutinized on the nanoscale: (1) chemical diffusion, (2) grain morphology, and (3) surface topography of the Ag layer. We found that nanoscale inhomogeneous distribution of In in InGaN/GaN quantum wells (QWs), interfacial diffusion (In/Ga out-diffusion into the Ag layer and diffusion of Ag into p-GaN and QWs), and Ag agglomeration deteriorate the light reflectivity, which account for the decreased luminous efficiency in VLEDs. Meanwhile, the surface morphology and topographical analyses revealed the nanomorphology of the Ag layer, where a nanograin size of ∼300 nm with special nanotwinned boundaries and an extremely smooth surface of ∼3-4 nm are strongly desired for better reflectivity. Further, on the basis of these microscopy results, suggestions on light extraction optimization are given to improve the performance of GaN-based blue VLEDs. Our findings enable fresh and deep understanding of performance-microstructure correlation of LEDs on the nanoscale, providing guidance to the design and manufacture of high-performance LED devices.

  19. Household light makes global heat: high black carbon emissions from kerosene wick lamps.

    Science.gov (United States)

    Lam, Nicholas L; Chen, Yanju; Weyant, Cheryl; Venkataraman, Chandra; Sadavarte, Pankaj; Johnson, Michael A; Smith, Kirk R; Brem, Benjamin T; Arineitwe, Joseph; Ellis, Justin E; Bond, Tami C

    2012-12-18

    Kerosene-fueled wick lamps used in millions of developing-country households are a significant but overlooked source of black carbon (BC) emissions. We present new laboratory and field measurements showing that 7-9% of kerosene consumed by widely used simple wick lamps is converted to carbonaceous particulate matter that is nearly pure BC. These high emission factors increase previous BC emission estimates from kerosene by 20-fold, to 270 Gg/year (90% uncertainty bounds: 110, 590 Gg/year). Aerosol climate forcing on atmosphere and snow from this source is estimated at 22 mW/m² (8, 48 mW/m²), or 7% of BC forcing by all other energy-related sources. Kerosene lamps have affordable alternatives that pose few clear adoption barriers and would provide immediate benefit to user welfare. The net effect on climate is definitively positive forcing as coemitted organic carbon is low. No other major BC source has such readily available alternatives, definitive climate forcing effects, and cobenefits. Replacement of kerosene-fueled wick lamps deserves strong consideration for programs that target short-lived climate forcers.

  20. Unregulated gaseous exhaust emission from modern ethanol fuelled light duty vehicles in cold ambient condition

    Science.gov (United States)

    Clairotte, M.; Adam, T. W.; Zardini, A. A.; Astorga, C.

    2011-12-01

    the first minutes of the cycle, before the light-off of the Three-Way Catalyst (TWC). Less ammonia has been emitted with ethanol fuel, in particular in low ambient condition (E75 versus E5). Ammonia is a harmful compound for human health and vegetation, and is a precursor of secondary aerosol. Even if agricultural activities are the main source of anthropogenic ammonia, the contribution from the transport sector increases significantly during the cold season. Consequently, using high concentrated ethanol as fuel may have a positive impact on ammonia emission in urban area. However, ethanol fuel had a negative impact on formaldehyde and acetaldehyde. The latter together with methane was notably emitted in low ambient temperature, in comparison with gasoline fuel (E5). Moreover, the OFP at -7°C was influenced by the amount of ethanol in gasoline, mainly because of the increase of ozone precursors linked to ethanol (ethylene, acetylene, and acetaldehyde). Even if ozone concentration levels are generally lower during the cold seasons these results show that the issue should be considered globally before promoting the use of high concentrated ethanol fuel in a large scale.

  1. Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

    Science.gov (United States)

    Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

    2012-11-01

    The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

  2. Broadband white light emission from Ce:AlN ceramics: High thermal conductivity down-converters for LED and laser-driven solid state lighting

    Directory of Open Access Journals (Sweden)

    A. T. Wieg

    2016-12-01

    Full Text Available We introduce high thermal conductivity aluminum nitride (AlN as a transparent ceramic host for Ce3+, a well-known active ion dopant. We show that the Ce:AlN ceramics have overlapping photoluminescent (PL emission peaks that cover almost the entire visible range resulting in a white appearance under 375 nm excitation without the need for color mixing. The PL is due to a combination of intrinsic AlN defect complexes and Ce3+ electronic transitions. Importantly, the peak intensities can be tuned by varying the Ce concentration and processing parameters, causing different shades of white light without the need for multiple phosphors or light sources. The Commission Internationale de l’Eclairage coordinates calculated from the measured spectra confirm white light emission. In addition, we demonstrate the viability of laser driven white light emission by coupling the Ce:AlN to a readily available frequency tripled Nd-YAG laser emitting at 355 nm. The high thermal conductivity of these ceramic down-converters holds significant promise for producing higher power white light sources than those available today.

  3. Energy transfer and colour tunability in UV light induced Tm3+/Tb3+/Eu3+: ZnB glasses generating white light emission.

    Science.gov (United States)

    Naresh, V; Gupta, Kiran; Parthasaradhi Reddy, C; Ham, Byoung S

    2017-03-15

    A promising energy transfer (Tm 3+ →Tb 3+ →Eu 3+ ) approach is brought forward to generate white light emission under ultraviolet (UV) light excitation for solid state lightening. Tm 3+ /Tb 3+ /Eu 3+ ions are combinedly doped in zinc borate glass system in view of understanding energy transfer process resulting in white light emission. Zinc borate (host) glass displayed optical and luminescence properties due to formation of Zn(II) x -[O(-II)] y centres in the ZnB glass matrix. At 360nm (UV) excitation, triply doped Tm 3+ /Tb 3+ /Eu 3+ : ZnB glasses simultaneously shown their characteristic emission bands in blue (454nm: 1 D 2 → 3 F 4 ), green (547nm: 5 D 4 → 7 F 5 ) and red (616nm: 5 D 0 → 7 F 2 ) regions. In triple ions doped glasses, energy transfer dynamics is discussed in terms of Forster-Dexter theory, excitation & emission profiles, lifetime curves and from partial energy level diagram of three ions. The role of Tb 3+ in ET from Tm 3+ →Eu 3+ was discussed using branch model. From emission decay analysis, energy transfer probability (P) and efficiency (η) were evaluated. Colour tunability from blue to white on varying (Tb 3+ , Eu 3+ ) content is demonstrated from Commission Internationale de L'Eclairage (CIE) chromaticity coordinates. Based on chromaticity coordinates, other colour related parameters like correlated colour temperature (CCT) and colour purity are also computed for the studied glass samples. An appropriate blending of such combination of rare earth ions could show better suitability as potential candidates in achieving multi-colour and warm/cold white light emission for white LEDs application in the field of solid state lightening. Copyright © 2016 Elsevier B.V. All rights reserved.

  4. Towards space based verification of CO2 emissions from strong localized sources: fossil fuel power plant emissions as seen by a CarbonSat constellation

    Directory of Open Access Journals (Sweden)

    T. Krings

    2011-12-01

    Full Text Available Carbon dioxide (CO2 is the most important man-made greenhouse gas (GHG that cause global warming. With electricity generation through fossil-fuel power plants now being the economic sector with the largest source of CO2, power plant emissions monitoring has become more important than ever in the fight against global warming. In a previous study done by Bovensmann et al. (2010, random and systematic errors of power plant CO2 emissions have been quantified using a single overpass from a proposed CarbonSat instrument. In this study, we quantify errors of power plant annual emission estimates from a hypothetical CarbonSat and constellations of several CarbonSats while taking into account that power plant CO2 emissions are time-dependent. Our focus is on estimating systematic errors arising from the sparse temporal sampling as well as random errors that are primarily dependent on wind speeds. We used hourly emissions data from the US Environmental Protection Agency (EPA combined with assimilated and re-analyzed meteorological fields from the National Centers of Environmental Prediction (NCEP. CarbonSat orbits were simulated as a sun-synchronous low-earth orbiting satellite (LEO with an 828-km orbit height, local time ascending node (LTAN of 13:30 (01:30 p.m. LT and achieves global coverage after 5 days. We show, that despite the variability of the power plant emissions and the limited satellite overpasses, one CarbonSat has the potential to verify reported US annual CO2 emissions from large power plants (≥5 Mt CO2 yr−1 with a systematic error of less than ~4.9% and a random error of less than ~6.7% for 50% of all the power plants. For 90% of all the power plants, the systematic error was less than ~12.4% and the random error was less than ~13%. We additionally investigated two different satellite configurations using a combination of 5 CarbonSats. One achieves global coverage everyday but only samples the targets at fixed local times. The other

  5. Light-induced changes of cubic and uniaxial magnetic aniosotropy in a magnet doped by strongly anisotropic ions

    Czech Academy of Sciences Publication Activity Database

    Zaytseva, I.; Stupakiewicz, A.; Maziewski, A.; Zablotskyy, Vitaliy A.

    254-255, - (2003), s. 118-120 ISSN 0304-8853. [Soft Magnetic Material Conference ( SMM 15). Bilbao, 05.09.2001-07.09.2001] Institutional research plan: CEZ:AV0Z1010914 Keywords : photomagnetic effects * light-induced anisotropy * garnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.910, year: 2003

  6. Selective scanning tunneling microscope light emission from rutile phase of VO2.

    Science.gov (United States)

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-28

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes.

  7. 3D fluorescence emission difference microscopy based on spatial light modulator

    Directory of Open Access Journals (Sweden)

    Guangyuan Zhao

    2016-05-01

    Full Text Available We report three-dimensional fluorescence emission difference (3D-FED microscopy using a spatial light modulator (SLM. Zero phase, 0–2π vortex phase and binary 0-pi phase are loaded on the SLM to generate the corresponding solid, doughnut and z-axis hollow excitation spot, respectively. Our technique achieves super-resolved image by subtracting three differently acquired images with proper subtractive factors. Detailed theoretical analysis and simulation tests are proceeded to testify the performance of 3D-FED. Also, the improvement of lateral and axial resolution is demonstrated by imaging 100nm fluorescent beads. The experiment yields lateral resolution of 140nm and axial resolution of approximate 380nm.

  8. Light particle emission as a probe of reaction mechanism and nuclear excitation

    International Nuclear Information System (INIS)

    Guerreau, D.

    1989-01-01

    The central part of these lectures will be dealing with the problem of energy dissipation. A good understanding of the mechanisms for the dissipation requires to study both peripheral and central collisions or, in other words, to look at the impact paramenter dependence. This should also provide valuable information on the time scale. In order to probe the reaction mechanism and nuclear excitation, one of the most powerful tool is unquestionably the observation of light particle emission, including neutrons and charged particles. Several examples will be discussed related to peripheral collisions (the fate of transfer reactions, the excitation energy generation, the production of projectile-like fragments) as well as inner collisions for which extensive studies have demonstrated the strength of intermediate energy heavy ions for the production of very hot nuclei and detailed study of their decay properties

  9. Applications of Light Amplification by Stimulated Emission of Radiation (Lasers) for Restorative Dentistry

    Science.gov (United States)

    Najeeb, Shariq; Khurshid, Zohaib; Zafar, Muhammad Sohail; Ajlal, Syed

    2016-01-01

    Light amplification by stimulated emission of radiation (laser) has been used widely in a range of biomedical and dental applications in recent years. In the field of restorative dentistry, various kinds of lasers have been developed for diagnostic (e.g. caries detection) and operative applications (e.g. tooth ablation, cavity preparation, restorations, bleaching). The main benefits for laser applications are patient comfort, pain relief and better results for specific applications. Major concerns for using dental lasers frequently are high cost, need for specialized training and sensitivity of the technique, thereby compromising its usefulness particularly in developing countries. The main aim of this paper is to evaluate and summarize the applications of lasers in restorative dentistry, including a comparison of the applications of lasers for major restorative dental procedures and conventional clinical approaches. A remarkable increase in the use of lasers for dental application is expected in the near future. PMID:26642047

  10. In-situ TEM study on structural change and light emission of a multiwall carbon nanotube during Joule heating

    Science.gov (United States)

    Nishikawa, K.; Asaka, K.; Nakahara, H.; Saito, Y.

    2018-01-01

    Structure changes of a multiwall carbon nanotube (MWNT) during Joule heating were studied with simultaneous measurement of light emission spectra. The outer shells of the MWNT peeled off one by one because of excessive heating. All the peeled outer shells finally disappeared and inner shells whose tips were closed emerged, i.e., a new MWNT was formed. Each diameter of the shells comprising the MWNT decreased compared with those before the fracture. Light emission spectra during Joule heating of an MWNT were composed of both the blackbody radiation and characteristic peaks. The peaks in the light emission spectra shifted to higher energies in accordance with shrinkage of the inner shells. The energies of the peaks in the spectra corresponded to energy gaps between van Hove singularities calculated from the diameters of the shells, indicating that the peaks in the spectra are attributed to the interband electron transition in the MWNT.

  11. Spatially Resolved Patchy Ly α Emission within the Central Kiloparsec of a Strongly Lensed Quasar Host Galaxy at z = 2.8

    Energy Technology Data Exchange (ETDEWEB)

    Bayliss, Matthew B.; Bordoloi, Rongmon [Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Sharon, Keren; Runnoe, Jessie; Johnson, Traci; Paterno-Mahler, Rachel [Department of Astronomy, University of Michigan, 1085 S. University Avenue, Ann Arbor, MI 48109 (United States); Acharyya, Ayan; Bian, Fuyan; Kewley, Lisa [RSAA, Australian National University, Cotter Road, Weston Creek, ACT 2611 (Australia); Gladders, Michael D. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Rigby, Jane R. [Astrophysics Science Division, NASA Goddard Space Flight Center, 8800 Greenbelt Road, Greenbelt, MD 20771 (United States); Dahle, Hakon [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029, Blindern, NO-0315 Oslo (Norway); Florian, Michael, E-mail: mbayliss@mit.edu [Department of Astronomy and Astrophysics, University of Chicago, Chicago, IL 60637 (United States)

    2017-08-20

    We report the detection of extended Ly α emission from the host galaxy of SDSS J2222+2745, a strongly lensed quasar at z = 2.8. Spectroscopic follow-up clearly reveals extended Ly α in emission between two images of the central active galactic nucleus (AGN). We reconstruct the lensed quasar host galaxy in the source plane by applying a strong lens model to HST imaging and resolve spatial scales as small as ∼200 pc. In the source plane, we recover the host galaxy morphology to within a few hundred parsecs of the central AGN and map the extended Ly α emission to its physical origin on one side of the host galaxy at radii ∼0.5–2 kpc from the central AGN. There are clear morphological differences between the Ly α and rest-frame ultraviolet stellar continuum emission from the quasar host galaxy. Furthermore, the relative velocity profiles of quasar Ly α , host galaxy Ly α , and metal lines in outflowing gas reveal differences in the absorbing material affecting the AGN and host galaxy. These data indicate the presence of patchy local intervening gas in front of the central quasar and its host galaxy. This interpretation is consistent with the central luminous quasar being obscured across a substantial fraction of its surrounding solid angle, resulting in strong anisotropy in the exposure of the host galaxy to ionizing radiation from the AGN. This work demonstrates the power of strong-lensing-assisted studies to probe spatial scales that are currently inaccessible by other means.

  12. An Unusual Strong Visible-Light Absorption Band in Red Anatase TiO2 Photocatalyst Induced by Atomic Hydrogen-Occupied Oxygen Vacancies.

    Science.gov (United States)

    Yang, Yongqiang; Yin, Li-Chang; Gong, Yue; Niu, Ping; Wang, Jian-Qiang; Gu, Lin; Chen, Xingqiu; Liu, Gang; Wang, Lianzhou; Cheng, Hui-Ming

    2018-02-01

    Increasing visible light absorption of classic wide-bandgap photocatalysts like TiO 2 has long been pursued in order to promote solar energy conversion. Modulating the composition and/or stoichiometry of these photocatalysts is essential to narrow their bandgap for a strong visible-light absorption band. However, the bands obtained so far normally suffer from a low absorbance and/or narrow range. Herein, in contrast to the common tail-like absorption band in hydrogen-free oxygen-deficient TiO 2 , an unusual strong absorption band spanning the full spectrum of visible light is achieved in anatase TiO 2 by intentionally introducing atomic hydrogen-mediated oxygen vacancies. Combining experimental characterizations with theoretical calculations reveals the excitation of a new subvalence band associated with atomic hydrogen filled oxygen vacancies as the origin of such band, which subsequently leads to active photo-electrochemical water oxidation under visible light. These findings could provide a powerful way of tailoring wide-bandgap semiconductors to fully capture solar light. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. When polarons meet polaritons: Exciton-vibration interactions in organic molecules strongly coupled to confined light fields

    Science.gov (United States)

    Wu, Ning; Feist, Johannes; Garcia-Vidal, Francisco J.

    2016-11-01

    We present a microscopic semianalytical theory for the description of organic molecules interacting strongly with a cavity mode. Exciton-vibration coupling within the molecule and exciton-cavity interaction are treated on an equal footing by employing a temperature-dependent variational approach. The interplay between strong exciton-vibration coupling and strong exciton-cavity coupling gives rise to a hybrid ground state, which we refer to as the lower polaron polariton. Explicit expressions for the ground-state wave function, the zero-temperature quasiparticle weight of the lower polaron polariton, the photoluminescence line strength, and the mean number of vibrational quanta are obtained in terms of the optimal variational parameters. The dependence of these quantities upon the exciton-cavity coupling strength reveals that strong cavity coupling leads to an enhanced vibrational dressing of the cavity mode, and at the same time a vibrational decoupling of the dark excitons, which in turn results in a lower polaron polariton resembling a single-mode dressed bare lower polariton in the strong-coupling regime. Thermal effects on several observables are briefly discussed.

  14. X-RAY EMISSION FROM STRONGLY ASYMMETRIC CIRCUMSTELLAR MATERIAL IN THE REMNANT OF KEPLER'S SUPERNOVA

    Energy Technology Data Exchange (ETDEWEB)

    Burkey, Mary T.; Reynolds, Stephen P.; Borkowski, Kazimierz J.; Blondin, John M., E-mail: reynolds@ncsu.edu [Department of Physics, North Carolina State University, Raleigh NC 27695-8202 (United States)

    2013-02-10

    Kepler's supernova remnant resulted from a thermonuclear explosion, but is interacting with circumstellar material (CSM) lost from the progenitor system. We describe a statistical technique for isolating X-ray emission due to CSM from that due to shocked ejecta. Shocked CSM coincides well in position with 24 {mu}m emission seen by Spitzer. We find most CSM to be distributed along the bright north rim, but substantial concentrations are also found projected against the center of the remnant, roughly along a diameter with position angle {approx}100 Degree-Sign . We interpret this as evidence for a disk distribution of CSM before the supernova, with the line of sight to the observer roughly in the disk plane. We present two-dimensional hydrodynamic simulations of this scenario in qualitative agreement with the observed CSM morphology. Our observations require Kepler to have originated in a close binary system with an asymptotic giant branch star companion.

  15. Anomalous Light Emission and Wide Photoluminescence Spectra in Graphene Quantum Dot: Quantum Confinement from Edge Microstructure.

    Science.gov (United States)

    Huang, Pu; Shi, Jun-Jie; Zhang, Min; Jiang, Xin-He; Zhong, Hong-Xia; Ding, Yi-Min; Cao, Xiong; Wu, Meng; Lu, Jing

    2016-08-04

    The physical origin of the observed anomalous photoluminescence (PL) behavior, that is, the large-size graphene quantum dots (GQDs) exhibiting higher PL energy than the small ones and the broadening PL spectra from deep ultraviolet to near-infrared, has been debated for many years. Obviously, it is in conflict with the well-accepted quantum confinement. Here we shed new light on these two notable debates by state-of-the-art first-principles calculations based on many-body perturbation theory. We find that quantum confinement is significant in GQDs with remarkable size-dependent exciton absorption/emission. The edge environment from alkaline to acidic conditions causes a blue shift of the PL peak. Furthermore, carbon vacancies are inclined to assemble at the GQD edge and form the tiny edge microstructures. The bound excitons, localized inside these edge microstructures, determine the anomalous PL behavior (blue and UV emission) of large-size GQDs. The bound excitons confined in the whole GQD lead to the low-energy transition.

  16. Quantum Dots in Two-Dimensional Perovskite Matrices for Efficient Near-Infrared Light Emission

    KAUST Repository

    Yang, Zhenyu

    2017-03-13

    Quantum-dot-in-perovskite solids are excellent candidates for infrared light-emitting applications. The first generation of dot-in-perovskite light-emitting diodes (LEDs) has shown bright infrared electroluminescence with tunable emission wavelength; however, their performance has been limited by degradation of the active layer at practical operating voltages. This arises from the instability of the three-dimensional (3D) organolead halide perovskite matrix. Herein we report the first dot-in-perovskite solids that employ two-dimensional (2D) perovskites as the matrix. 2D perovskite passivation is achieved via an in situ alkylammonium/alkylamine substitution carried out during the quantum dot (QD) ligand exchange process. This single-step film preparation process enables deposition of the QD/perovskite active layers with thicknesses of 40 nm, over seven times thinner than the first-generation dot-in-perovskite thin films that relied on a multistep synthesis. The dot-in-perovskite film roughness improved from 31 nm for the first-generation films to 3 nm for films as a result of this new approach. The best devices exhibit external quantum efficiency peaks exceeding 2% and radiances of ∼1 W sr–1 m–2, with an improved breakdown voltage up to 7.5 V. Compared to first-generation dot-in-perovskites, this new process reduces materials consumptions 10-fold and represents a promising step toward manufacturable devices.

  17. Blue light treatment of Pseudomonas aeruginosa: Strong bactericidal activity, synergism with antibiotics and inactivation of virulence factors.

    Science.gov (United States)

    Fila, Grzegorz; Kawiak, Anna; Grinholc, Mariusz Stanislaw

    2017-08-18

    Pseudomonas aeruginosa is among the most common pathogens responsible for both acute and chronic infections of high incidence and severity. Additionally, P. aeruginosa resistance to conventional antimicrobials has increased rapidly over the past decade. Therefore, it is crucial to explore new therapeutic options, particularly options that specifically target the pathogenic mechanisms of this microbe. The ability of a pathogenic bacterium to cause disease is dependent upon the production of agents termed 'virulence factors', and approaches to mitigate these agents have gained increasing attention as new antibacterial strategies. Although blue light irradiation is a promising alternative approach, only limited and preliminary studies have described its effect on virulence factors. The current study aimed to investigate the effects of lethal and sub-lethal doses of blue light treatment (BLT) on P. aeruginosa virulence factors. We analyzed the inhibitory effects of blue light irradiation on the production/activity of several virulence factors. Lethal BLT inhibited the activity of pyocyanin, staphylolysin, pseudolysin and other proteases, but sub-lethal BLT did not affect the production/expression of proteases, phospholipases, and flagella- or type IV pili-associated motility. Moreover, a eukaryotic cytotoxicity test confirmed the decreased toxicity of blue light-treated extracellular P. aeruginosa fractions. Finally, the increased antimicrobial susceptibility of P. aeruginosa treated with sequential doses of sub-lethal BLT was demonstrated with a checkerboard test. Thus, this work provides evidence-based proof of the susceptibility of drug-resistant P. aeruginosa to BLT-mediated killing, accompanied by virulence factor reduction, and describes the synergy between antibiotics and sub-lethal BLT.

  18. Light absorption of biomass burning and vehicle emission-sourced carbonaceous aerosols of the Tibetan Plateau.

    Science.gov (United States)

    Hu, Zhaofu; Kang, Shichang; Li, Chaoliu; Yan, Fangping; Chen, Pengfei; Gao, Shaopeng; Wang, Zhiyong; Zhang, Yulan; Sillanpää, Mika

    2017-06-01

    Carbonaceous aerosols over the Tibetan Plateau originate primarily from biomass burning and vehicle emissions (BB and VEs, respectively). The light absorption characteristics of these carbonaceous aerosols are closely correlated with the burning conditions and represent key factors that influence climate forcing. In this study, the light absorption characteristics of elemental carbon (EC) and water-soluble organic carbon (WSOC) in PM 2.5 (fine particulate matter smaller than 2.5 μm) generated from BB and VEs were investigated over the Tibetan Plateau (TP). The results showed that the organic carbon (OC)/EC ratios from BB- and VE-sourced PM 2.5 were 17.62 ± 10.19 and 1.19 ± 0.36, respectively. These values were higher than the ratios in other regions, which was primarily because of the diminished amount of oxygen over the TP. The mass absorption cross section of EC (MAC EC ) at 632 nm for the BB-sourced PM 2.5 (6.10 ± 1.21 m 2 .g -1 ) was lower than that of the VE-sourced PM 2.5 (8.10 ± 0.98 m 2 .g -1 ), indicating that the EC content of the BB-sourced PM 2.5 was overestimated because of the high OC/EC ratio. The respective absorption per mass (α/ρ) values at 365 nm for the VE- and BB-sourced PM 2.5 were 0.71 ± 0.17 m 2 .g -1 and 0.91 ± 0.18 m 2 .g -1 . The α/ρ value of the VEs was loaded between that of gasoline and diesel emissions, indicating that the VE-sourced PM 2.5 originated from both types of emissions. Because OC and WSOC accounts for most of the carbonaceous aerosols at remote area of the TP, the radiative forcing contributed by the WSOC should be high, and requires further investigation.

  19. Carbon dioxide emission trends in cars and light trucks: A comparative analysis of emissions and methodologies for Florida's counties (2000 and 2008)

    International Nuclear Information System (INIS)

    Garren, S.J.; Pinjari, A.R.; Brinkmann, R.

    2011-01-01

    This paper investigates methodologies to quantify CO 2 emissions from cars and light trucks in Florida. The most widely used methodology to calculate greenhouse gas emissions in the transportation sector at the local level uses a harmonic average (HA) methodology based on nationally averaged fuel economies that assume 55% city and 45% highway VMTs. This paper presents a local condition (LC) methodology that accounts for county-level variations in city and highway VMTs, as opposed to assumed uniform driving conditions. Both HA and LC methodologies were used to estimate and compare absolute and per capita CO 2 emissions both statewide and counties for 2000 and 2008. From 2000 to 2008, statewide absolute and per capita CO 2 emissions increased similarly using HA and LC methodologies; however, the percent change varied considerably among counties. Statewide CO 2 emissions calculated from HA and LC methodologies differed by only -0.2% (2000) and 1.7% (2008); however, the differences in the county-level emissions ranged from -8.0% to 14.9% (2000) and from -5.6% to 17.0% (2008). While either the HA or the LC methodology yields a similar result statewide, significant variation exists at the county level, warranting the need to consider local driving conditions when estimating county-level emissions. - Highlights: → The paper evaluates GHG emission methods for on-road passenger vehicles in Florida. → The paper compares methods that assume the harmonic average with actual VMTs driven. → The paper analyzes statewide GHG emissions aggregated by county for 2000 and 2008. → The paper improves on methods that balance bottom-up with top-down GHG emissions.

  20. 40 CFR 86.1709-99 - Exhaust emission standards for 1999 and later light light-duty trucks.

    Science.gov (United States)

    2010-07-01

    ... emissions measured on the federal Highway Fuel Economy Test in 40 CFR part 600, subpart B, shall be not.... Both the projected emissions and the Highway Fuel Economy Test standard shall be rounded to the nearest... effectiveness. A/C-on specific “open-loop” or “commanded enrichment” air-fuel enrichment strategies (as defined...

  1. Tuning the color emission of thin film molecular organic light emitting devices by the solid state solvation effect

    Science.gov (United States)

    Bulović, V.; Deshpande, R.; Thompson, M. E.; Forrest, S. R.

    1999-07-01

    We demonstrate a general method for tuning the luminescent emission spectrum of dipolar molecules by adjusting the strength of intermolecular dipole-dipole interactions using a doped guest-host molecular organic thin film system. Spectral shifting is achieved by introducing dopants that change the local electric field in the film. This `solid state solvation effect' is used to continuously tune, by up to 75 nm, the peak emission wavelength of organic light emitting devices consisting of triarylamine host materials doped with polar luminescent dyes DCM2, aluminum tris(8-hydroxyquinoline), or both. Red, orange, yellow, green, blue, and white emission is demonstrated with the same set of organic molecules.

  2. Towards strong light-matter coupling at the single-resonator level with sub-wavelength mid-infrared nano-antennas

    Energy Technology Data Exchange (ETDEWEB)

    Malerba, M.; De Angelis, F., E-mail: francesco.deangelis@iit.it [Istituto Italiano di Tecnologia, Via Morego, 30, I-16163 Genova (Italy); Ongarello, T.; Paulillo, B.; Manceau, J.-M.; Beaudoin, G.; Sagnes, I.; Colombelli, R., E-mail: raffaele.colombelli@u-psud.fr [Centre for Nanoscience and Nanotechnology (C2N Orsay), CNRS UMR9001, Univ. Paris Sud, Univ. Paris Saclay, 91405 Orsay (France)

    2016-07-11

    We report a crucial step towards single-object cavity electrodynamics in the mid-infrared spectral range using resonators that borrow functionalities from antennas. Room-temperature strong light-matter coupling is demonstrated in the mid-infrared between an intersubband transition and an extremely reduced number of sub-wavelength resonators. By exploiting 3D plasmonic nano-antennas featuring an out-of-plane geometry, we observed strong light-matter coupling in a very low number of resonators: only 16, more than 100 times better than what reported to date in this spectral range. The modal volume addressed by each nano-antenna is sub-wavelength-sized and it encompasses only ≈4400 electrons.

  3. Fleet average NOx emission performance of 2007 model year light-duty vehicles, light-duty trucks and medium-duty passenger vehicles

    International Nuclear Information System (INIS)

    2009-09-01

    This report summarized the regulatory requirements related to nitrous oxide (NO x ) fleet averaging for light-duty vehicles, light-duty trucks, and medium-duty passenger vehicles under the On-Road Vehicle and Engine Emission Regulations. The regulations introduced more stringent national emission standards for on-road vehicles and engines and include technical standards that establish maximum limits on vehicle exhaust emissions. The fleet average NO x emission performance of individual companies and the overall Canadian fleet for 2007 was summarized, and the effectiveness of the Canadian fleet average NO x emission program was evaluated in relation to its environmental performance objectives. A total of 22 companies submitted reports for 294 test groups comprising 1,599,051 vehicles of the 2007 model year. The average NO x value for the entire LDV/LLDT fleet was 0.06897630 grams per mile. The average value for the HLDT/MDPV fleet was 0.160668 grams per mile. NO x values for both overall fleets remained better than the corresponding fleet average NO x standards, and were consistent with the environmental performance objectives of the regulations. 9 tabs., 3 figs.

  4. Fleet average NOx emission performance of 2004 model year light-duty vehicles, light-duty trucks and medium-duty passenger vehicles

    International Nuclear Information System (INIS)

    2006-05-01

    The On-Road Vehicle and Engine Emission Regulations came into effect on January 1, 2004. The regulations introduced more stringent national emission standards for on-road vehicles and engines, and also required that companies submit reports containing information concerning the company's fleets. This report presented a summary of the regulatory requirements relating to nitric oxide (NO x ) fleet average emissions for light-duty vehicles, light-duty trucks, and medium-duty passenger vehicles under the new regulations. The effectiveness of the Canadian fleet average NO x emission program at achieving environmental performance objectives was also evaluated. A summary of the fleet average NO x emission performance of individual companies was presented, as well as the overall Canadian fleet average of the 2004 model year based on data submitted by companies in their end of model year reports. A total of 21 companies submitted reports covering 2004 model year vehicles in 10 test groups, comprising 1,350,719 vehicles of the 2004 model year manufactured or imported for the purpose of sale in Canada. The average NO x value for the entire Canadian LDV/LDT fleet was 0.2016463 grams per mile. The average NO x values for the entire Canadian HLDT/MDPV fleet was 0.321976 grams per mile. It was concluded that the NO x values for both fleets were consistent with the environmental performance objectives of the regulations for the 2004 model year. 9 tabs

  5. BaZrO3 perovskite nanoparticles as emissive material for organic/inorganic hybrid light-emitting diodes

    DEFF Research Database (Denmark)

    Tamulevičius, S.; Ivaniuk, K.; Cherpak, V.

    2017-01-01

    . Such double-channel emission provides a broadening of the electroluminescence spectrum and a resultant yellow-green emission color of the device. We have realized an energy transfer from the exciplexes arranged by the interface between two organic layers and the spherical-shaped BaZrO3 nanoparticles randomly.......26%. In order to estimate the efficiency of the energy transfer from the exciplex to the BaZrO3 nanoparticles we have applied the Förster model for the dipole-dipole energy transfer accounting for the mutual overlap of the exciplex emission spectrum and the absorption spectrum of the BaZrO3 nanoparticles.......In the present work we have demonstrated double-channel emission from organic exciplexes coupled to inorganic nanoparticles. The process is demonstrated by yellow-green emission in light-emitting diodes based on organic exciplexes hybridized with perovskite-type dispersed BaZrO3 nanoparticles...

  6. Long-term implications of alternative light-duty vehicle technologies for global greenhouse gas emissions and primary energy demands

    International Nuclear Information System (INIS)

    Kyle, Page; Kim, Son H.

    2011-01-01

    This study assesses global light-duty vehicle (LDV) transport in the upcoming century, and the implications of vehicle technology advancement and fuel-switching on greenhouse gas emissions and primary energy demands. Five different vehicle technology scenarios are analyzed with and without a CO 2 emissions mitigation policy using the GCAM integrated assessment model: a reference internal combustion engine vehicle scenario, an advanced internal combustion engine vehicle scenario, and three alternative fuel vehicle scenarios in which all LDVs are switched to natural gas, electricity, or hydrogen by 2050. The emissions mitigation policy is a global CO 2 emissions price pathway that achieves 450 ppmv CO 2 at the end of the century with reference vehicle technologies. The scenarios demonstrate considerable emissions mitigation potential from LDV technology; with and without emissions pricing, global CO 2 concentrations in 2095 are reduced about 10 ppmv by advanced ICEV technologies and natural gas vehicles, and 25 ppmv by electric or hydrogen vehicles. All technological advances in vehicles are important for reducing the oil demands of LDV transport and their corresponding CO 2 emissions. Among advanced and alternative vehicle technologies, electricity- and hydrogen-powered vehicles are especially valuable for reducing whole-system emissions and total primary energy. - Highlights: → Alternative-fuel LDVs reduce whole-system CO 2 emissions, even without carbon pricing. → Alternative-fuel LDVs enhance the CO 2 mitigation capacity of the transportation sector. → Electric and hydrogen vehicles reduce whole-system primary energy supporting LDV transport.

  7. Modulation of intersubband light absorption and interband photoluminescence in double GaAs/AlGaAs quantum wells under strong lateral electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Balagula, R. M., E-mail: rmbal@spbstu.ru; Vinnichenko, M. Ya., E-mail: mvin@spbstu.ru; Makhov, I. S.; Firsov, D. A.; Vorobjev, L. E. [Peter the Great Saint-Petersburg Polytechnic University (Russian Federation)

    2016-11-15

    The effect of a lateral electric field on the mid-infrared absorption and interband photoluminescence spectra in double tunnel-coupled GaAs/AlGaAs quantum wells is studied. The results obtained are explained by the redistribution of hot electrons between quantum wells and changes in the space charge in the structure. The hot carrier temperature is determined by analyzing the intersubband light absorption and interband photoluminescence modulation spectra under strong lateral electric fields.

  8. Radio emission from the X-ray pulsar Her X-1: a jet launched by a strong magnetic field neutron star?

    Science.gov (United States)

    van den Eijnden, J.; Degenaar, N.; Russell, T. D.; Miller-Jones, J. C. A.; Wijnands, R.; Miller, J. M.; King, A. L.; Rupen, M. P.

    2018-01-01

    Her X-1 is an accreting neutron star (NS) in an intermediate-mass X-ray binary. Like low-mass X-ray binaries (LMXBs), it accretes via Roche lobe overflow, but similar to many high-mass X-ray binaries containing a NS; Her X-1 has a strong magnetic field and slow spin. Here, we present the discovery of radio emission from Her X-1 with the Very Large Array. During the radio observation, the central X-ray source was partially obscured by a warped disc. We measure a radio flux density of 38.7 ± 4.8 μJy at 9 GHz but cannot constrain the spectral shape. We discuss possible origins of the radio emission, and conclude that coherent emission, a stellar wind, shocks and a propeller outflow are all unlikely explanations. A jet, as seen in LMXBs, is consistent with the observed radio properties. We consider the implications of the presence of a jet in Her X-1 on jet formation mechanisms and on the launching of jets by NSs with strong magnetic fields.

  9. Strong photonic crystal behavior in regular arrays of core-shell and quantum disc InGaN/GaN nanorod light-emitting diodes

    International Nuclear Information System (INIS)

    Lewins, C. J.; Le Boulbar, E. D.; Lis, S. M.; Shields, P. A.; Allsopp, D. W. E.; Edwards, P. R.; Martin, R. W.

    2014-01-01

    We show that arrays of emissive nanorod structures can exhibit strong photonic crystal behavior, via observations of the far-field luminescence from core-shell and quantum disc InGaN/GaN nanorods. The conditions needed for the formation of directional Bloch modes characteristic of strong photonic behavior are found to depend critically upon the vertical shape of the nanorod sidewalls. Index guiding by a region of lower volume-averaged refractive index near the base of the nanorods creates a quasi-suspended photonic crystal slab at the top of the nanorods which supports Bloch modes. Only diffractive behavior could be observed without this region. Slab waveguide modelling of the vertical structure shows that the behavioral regime of the emissive nanorod arrays depends strongly upon the optical coupling between the nanorod region and the planar layers below. The controlled crossover between the two regimes of photonic crystal operation enables the design of photonic nanorod structures formed on planar substrates that exploit either behavior depending on device requirements.

  10. 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....

  11. Forbidden singlet exciton transitions induced by localization in polymer light-emitting diodes in a strong electric field.

    Science.gov (United States)

    Sun, Zheng; Xu, Yuan-Ping; Li, Sheng; George, Thomas F

    2011-02-10

    Through combining the electron transition process and dipole moment evolution as well as electron-phonon coupling, molecular dynamics calculations show that the radiative decay of singlet excitons in a conjugated polymer, such as a polymer light-emitting diode (PLED), is largely determined by the evolution of the dipole moment. Without an electric field, the decay life of a singlet exciton is about 1 ns. Once an electric field is applied and exceeds a critical value, with electron-phonon coupling, the original lattice structure evolves into two new localized lattice distortions, consistent with the experimental results. Owing to the new lattice structure and self-trapping, the dipole moment rapidly decreases to zero within 5 fs, eliminating the radiative decay of the singlet exciton.

  12. Strong Visible Light Photocatalytic Activity of Magnetically Recyclable Sol-Gel-Synthesized ZnFe2O4 for Rhodamine B Degradation

    Science.gov (United States)

    Xu, Xiaoli; Xiao, Lingbo; Jia, Yanmin; Hong, Yuantign; Ma, Jiangping; Wu, Zheng

    2018-01-01

    Visible light-responsive ZnFe2O4 photocatalyst with a spinel structure was synthesized via a sol-gel method. The visible light photocatalysis of ZnFe2O4 was investigated by decomposing Rhodamine B (RhB) solution. Under ˜30 min of visible light irradiation, the decomposition ratio of RhB is up to ˜97.4%. The excellent photocatalytic performance of ZnFe2O4 photocatalyst is attributed to the high effective oxidation-reduction reaction caused by light irradiation excitation. With the increase of decomposition time, the wavelength of the maximum absorption peak of RhB solutions shifts from 557 nm to 498 nm ("blue shift"), which is because of the N-deethylation and cleavage of the conjugated chromophore structure of RhB. ZnFe2O4 photocatalyst also exhibits a weak ferromagnetism performance. The decomposition ratio of RhB for the magnetically recycled ZnFe2O4 is ˜94.6%. Strong visible light photocatalysis and convenience of magnetic recycling make ZnFe2O4 promising for photocatalytic applications in dye wastewater treatment.

  13. Importance of strong-correlation on the lattice dynamics of light-actinides Th-Pa alloy

    Science.gov (United States)

    de La Peã+/-A Seaman, Omar; Heid, Rolf; Bohnen, Klaus-Peter

    We have studied the structural, electronic, and lattice dynamics of the Th1-xPax actinide alloy. This system have been analyzed within the framework of density functional perturbation theory, using a mixed-basis pseudopotential method and the virtual crystal approximation (VCA) for modeling the alloy. In particular, the energetics is analyzed as the ground-state crystal structure is changed form fcc to bct, as well as the electronic density of states (DOS), and the phonon frequencies. Such properties have been calculated with and without strong correlations effects through the LDA+U formalism. Although the strong-correlation does not influence on a great manner the Th properties, such effects are more important as the content increases towards Pa, affecting even the definition of the ground-state crystal structure for Pa (experimentally determined as bct). The evolution of the density of states at the Fermi level (N (EF)) and the phonon frequencies as a function of Pa-content are presented and discussed in detail, aiming to understand their influence on the electron-phonon coupling for the Th-Pa alloy. This research was supported by Conacyt-México under project No. CB2013-221807-F.

  14. THE LICK AGN MONITORING PROJECT 2011: SPECTROSCOPIC CAMPAIGN AND EMISSION-LINE LIGHT CURVES

    Energy Technology Data Exchange (ETDEWEB)

    Barth, Aaron J. [Department of Physics and Astronomy, 4129 Frederick Reines Hall, University of California, Irvine, CA, 92697-4575 (United States); Bennert, Vardha N. [Physics Department, California Polytechnic State University, San Luis Obispo, CA 93407 (United States); Canalizo, Gabriela [Department of Physics and Astronomy, University of California, Riverside, CA 92521 (United States); Filippenko, Alexei V.; Li, Weidong [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States); Gates, Elinor L. [Lick Observatory, P.O. Box 85, Mount Hamilton, CA 95140 (United States); Greene, Jenny E. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Malkan, Matthew A.; Treu, Tommaso [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States); Pancoast, Anna [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Sand, David J. [Texas Tech University, Physics Department, Box 41051, Lubbock, TX 79409-1051 (United States); Stern, Daniel [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Boulevard, Pasadena, CA 91109 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University, Seoul 151-742 (Korea, Republic of); Assef, Roberto J. [Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago (Chile); Bae, Hyun-Jin [Department of Astronomy and Center for Galaxy Evolution Research, Yonsei University, Seoul 120-749 (Korea, Republic of); Brewer, Brendon J. [Department of Statistics, The University of Auckland, Private Bag 92019, Auckland 1142 (New Zealand); Cenko, S. Bradley [Astrophysics Science Division, NASA Goddard Space Flight Center, MC 661, Greenbelt, MD 20771 (United States); and others

    2015-04-15

    In the Spring of 2011 we carried out a 2.5 month reverberation mapping campaign using the 3 m Shane telescope at Lick Observatory, monitoring 15 low-redshift Seyfert 1 galaxies. This paper describes the observations, reductions and measurements, and data products from the spectroscopic campaign. The reduced spectra were fitted with a multicomponent model in order to isolate the contributions of various continuum and emission-line components. We present light curves of broad emission lines and the active galactic nucleus (AGN) continuum, and measurements of the broad Hβ line widths in mean and rms spectra. For the most highly variable AGNs we also measured broad Hβ line widths and velocity centroids from the nightly spectra. In four AGNs exhibiting the highest variability amplitudes, we detect anticorrelations between broad Hβ width and luminosity, demonstrating that the broad-line region “breathes” on short timescales of days to weeks in response to continuum variations. We also find that broad Hβ velocity centroids can undergo substantial changes in response to continuum variations; in NGC 4593, the broad Hβ velocity shifted by ∼250 km s{sup −1} over a 1 month period. This reverberation-induced velocity shift effect is likely to contribute a significant source of confusion noise to binary black hole searches that use multi-epoch quasar spectroscopy to detect binary orbital motion. We also present results from simulations that examine biases that can occur in measurement of broad-line widths from rms spectra due to the contributions of continuum variations and photon-counting noise.

  15. Evaluation of emission factors for light-duty gasoline vehicles based on chassis dynamometer and tunnel studies in Shanghai, China

    Science.gov (United States)

    Huang, Cheng; Tao, Shikang; Lou, Shengrong; Hu, Qingyao; Wang, Hongli; Wang, Qian; Li, Li; Wang, Hongyu; Liu, Jian'gang; Quan, Yifeng; Zhou, Lanlan

    2017-11-01

    CO, THC, NOx, and PM emission factors of 51 light-duty gasoline vehicles (LDGVs) spanning the emission standards from Euro 2 to Euro 5 were measured by a chassis dynamometer. High frequencies of high-emitting vehicles were observed in Euro 2 and Euro 3 LDGV fleet. 56% and 33% of high-emitting vehicles contributed 81%-92% and 82%-85% of the emissions in Euro 2 and Euro 3 test fleet, respectively. Malfunctions of catalytic convertors after high strength use are the main cause of the high emissions. Continuous monitoring of a gasoline vehicle dominated tunnel in Shanghai, China was conducted to evaluate the average emission factors of vehicles in real-world. The results indicated that the emission factors of LDGVs were considerably underestimated in EI guidebook in China. The overlook of high-emitting vehicles in older vehicle fleet is the main reason for this underestimation. Enhancing the supervision of high emission vehicles and strengthening the compliance tests of in-use vehicles are essential measures to control the emissions of in-use gasoline vehicles at the present stage in China.

  16. Graphene Quantum Dot Solid Sheets: Strong blue-light-emitting & photocurrent-producing band-gap-opened nanostructures.

    Science.gov (United States)

    Bharathi, Ganapathi; Nataraj, Devaraj; Premkumar, Sellan; Sowmiya, Murugaiyan; Senthilkumar, Kittusamy; Thangadurai, T Daniel; Khyzhun, Oleg Yu; Gupta, Mukul; Phase, Deodatta; Patra, Nirmalendu; Jha, Shambhu Nath; Bhattacharyya, Dibyendu

    2017-09-07

    Graphene has been studied intensively in opto-electronics, and its transport properties are well established. However, efforts to induce intrinsic optical properties are still in progress. Herein, we report the production of micron-sized sheets by interconnecting graphene quantum dots (GQDs), which are termed 'GQD solid sheets', with intrinsic absorption and emission properties. Since a GQD solid sheet is an interconnected QD system, it possesses the optical properties of GQDs. Metal atoms that interconnect the GQDs in the bottom-up hydrothermal growth process, induce the semiconducting behaviour in the GQD solid sheets. X-ray absorption measurements and quantum chemical calculations provide clear evidence for the metal-mediated growth process. The as-grown graphene quantum dot solids undergo a Forster Resonance Energy Transfer (FRET) interaction with GQDs to exhibit an unconventional 36% photoluminescence (PL) quantum yield in the blue region at 440 nm. A high-magnitude photocurrent was also induced in graphene quantum dot solid sheets by the energy transfer process.

  17. Triple-doped KMnF3:Yb3+/Er3+/Tm3+ nanocubes: four-color upconversion emissions with strong red and near-infrared bands

    Science.gov (United States)

    Wang, Hao; Hong, Xiaodong; Han, Renlu; Shi, Junhui; Liu, Zongjun; Liu, Shujuan; Wang, You; Gan, Yang

    2015-11-01

    Triple-doped (Yb3+/Er3+/Tm3+) KMnF3 nanocubes with uniform sizes of 250 nm were synthesized by a facile hydrothermal route using the oleic acid as the capping agent. It was found that these nanocubes can simultaneously exhibited four-color (blue, green, red and NIR) upconversion emissions under a single 980 nm near-infrared (NIR) laser excitation, which should have potential multicolor in vivo imaging applications. Specifically, the red (660 nm) and NIR (800 nm) peaks, known as two “optical windows” for imaging biological tissues, were strong. The spectral and pump analyses indicated the two-photon processes were responsible for the both red and NIR emissions.

  18. From carbon to light. A new framework for estimating greenhouse gas emissions reductions from replacing fuel-based lighting with LED systems

    Energy Technology Data Exchange (ETDEWEB)

    Mills, E. [Lawrence Berkeley National Laboratory LBNL, 1 Cyclotron Road, Berkeley, CA 94720 (United States); Jacobson, A. [Office of Policy and International Affairs, US Department of Energy, 1000 Independence Avenue SW, Washington, DC 20585 (United States)

    2011-11-15

    There is considerable well-intended, yet wishful anticipation about reducing greenhouse gas emissions by replacing fuel-based lighting in the developing world with grid-independent light-emitting diode (LED) lighting systems. Most estimates gloss over important practical realities that stand to erode a genuinely significant potential. The Clean Development Mechanism (CDM) is the leading system for quantifying the benefits of such projects in developing countries and embodying them in a market-based platform for trading carbon credits. However, compliance with methodologies for highly decentralized, small-scale energy saving projects currently employed in the CDM is viewed by developers of as onerous, time-consuming, and costly. In recognition of the problem, the CDM has recently placed priority on improved methodologies for estimating carbon dioxide reductions from displacement of fuel-based lighting with energy-efficient alternatives. The over-arching aim is to maintain environmental integrity without stifling sustainable emission-reduction projects and programs in the field. This article informs this process by laying out a new framework that shifts the analytical focus from highly costly yet narrow and uncertain baseline estimations to simplified methods based primarily on deemed values that focus on replacement lighting system quality and performance characteristics. The result - many elements of which have been adopted in a new methodology approved by the CDM - is more structured and rigorous than methodologies used for LED projects in the past and yet simpler to implement, i.e., entailing fewer transaction costs. Applying this new framework, we find that some off-grid lighting technologies can be expected to yield little or no emissions reductions, while well-designed ones, using products independently certified to have high quality and durability, can generate significant reductions. Enfolding quality assurance within the proposed framework will help stem

  19. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  20. Strong optical-mechanical coupling in a vertical GaAs/AlAs microcavity for subterahertz phonons and near-infrared light.

    Science.gov (United States)

    Fainstein, A; Lanzillotti-Kimura, N D; Jusserand, B; Perrin, B

    2013-01-18

    We show that distributed Bragg reflector GaAs/AlAs vertical cavities designed to confine photons are automatically optimal to confine phonons of the same wavelength, strongly enhancing their interaction. We study the impulsive generation of intense coherent and monochromatic acoustic phonons by following the time evolution of the elastic strain in picosecond-laser experiments. Efficient optical detection is assured by the strong phonon backaction on the high-Q optical cavity mode. Large optomechanical factors are reported (~THz/nm range). Pillar cavities based in these structures are predicted to display picogram effective masses, almost perfect sound extraction, and threshold powers for the stimulated emission of phonons in the range μW-mW, opening the way for the demonstration of phonon "lasing" by parametric instability in these devices.

  1. Synthesis of silver nanoprisms: A photochemical approach using light emission diodes

    Energy Technology Data Exchange (ETDEWEB)

    Saade, Jamil, E-mail: j.saade@yahoo.com.br [Programa de Pós Graduação em Ciência de Materiais, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil); Araújo, Cid B. de, E-mail: cid@df.ufpe.br [Departamento de Física, Universidade Federal de Pernambuco, 50670-901 Recife, PE (Brazil)

    2014-12-15

    We report a simplified photochemical methodology for fabrication of silver nanoprisms (Ag-NPs). The particles, synthesized in aqueous solution, were produced by illumination with narrow band and low cost Light Emission Diodes (LEDs) and exhibit Localized Surface Plasmon Resonances (LSPR) from the blue to the near-infrared. The new methodology consists of one pot synthesis that uses only three chemical reagents and allows good control of the sizes and the aspect ratios of triangular Ag-NPs. Reduction of silver ions by trisodium citrate (TSC), catalyzed on silver seeds, is exploited to synthesize and to control the growth of the Ag-NPs. The growth kinetics of the particles was characterized by monitoring the LSPR absorption band during several hours under continuous illumination. Optical absorption, transmission electron microscopy (TEM), electron diffraction and zeta potential measurements were performed to characterize the shape and size of the Ag-NPs and the colloid stability during its synthesis and aging. The TEM images and extinction spectra revealed Ag-NPs with good size dispersion and narrow LSPR bands with great potential for applications in nanotechnology. - Highlights: • Efficient method to synthesize Ag nanoprisms using only three chemical reagents. • Practicality: it removes the needs for some steps used in photochemical synthesis. • Zeta Potential measurements revealed the best conditions for colloids stability. • Non-coherent-radiation-induced dipoles cause aggregation of similar nanoprisms. • Data confirmed step-like-structures on the nanoprisms surface due to their aging.

  2. Influence of emissive hole-transporting materials on the electrical and luminescent performance of highly efficient white light organic light-emitting diodes

    Science.gov (United States)

    Wang, Ching-Wu; Chen, Shih-Fang; Kuo, Wen-Fa

    2002-09-01

    An emissive hole-transporting material with a dopant was proposed for realizing highly efficient and relatively pure white-light organic light-emitting diode (OLED). The device structure included ITO/N, N'-diphenyl-N, N'-bis(1-naphthyl-phenyl)-(1, 1'-biphenyl)-4,4'-diamine (NPB)/NPB doped with 4-Dicyanomethylene-2-methyl-6-[2, 3, 6, 7-tetra-hydro-1H, 5H-behzo[ij]-quinolizin-8-yl)vinyl]-4H-pyran (DCM2) (NPB:DCM2)/bathocuproine (BCP)/tris-(8-hydroxyquinoline) aluminum (Alq3)/Mg/Ag. By appropriately controlling the DCM2 doping concentration as well as thickness of the blue-red-emitting layer of NPB:DCM2, the white-light OLED has a relatively stable white color even the operating voltages change from 9 to 18 V.

  3. Dark exposure of petunia cuttings strongly improves adventitious root formation and enhances carbohydrate availability during rooting in the light.

    Science.gov (United States)

    Klopotek, Yvonne; Haensch, Klaus-Thomas; Hause, Bettina; Hajirezaei, Mohammad-Reza; Druege, Uwe

    2010-05-01

    The effect of temporary dark exposure on adventitious root formation (ARF) in Petuniaxhybrida 'Mitchell' cuttings was investigated. Histological and metabolic changes in the cuttings during the dark treatment and subsequent rooting in the light were recorded. Excised cuttings were exposed to the dark for seven days at 10 degrees C followed by a nine-day rooting period in perlite or were rooted immediately for 16 days in a climate chamber at 22/20 degrees C (day/night) and a photosynthetic photon flux density (PPFD) of 100micromolm(-2)s(-1). Dark exposure prior to rooting increased, accelerated and synchronized ARF. The rooting period was reduced from 16 days (non-treated cuttings) to 9 days (treated cuttings). Under optimum conditions, despite the reduced rooting period, dark-exposed cuttings produced a higher number and length of roots than non-treated cuttings. An increase in temperature to 20 degrees C during the dark treatment or extending the cold dark exposure to 14 days caused a similar enhancement of root development compared to non-treated cuttings. Root meristem formation had already started during the dark treatment and was enhanced during the subsequent rooting period. Levels of soluble sugars (glucose, fructose and sucrose) and starch in leaf and basal stem tissues significantly decreased during the seven days of dark exposure. This depletion was, however, compensated during rooting after 6 and 24h for soluble sugars in leaves and the basal stem, respectively, whereas the sucrose level in the basal stem was already increased at 6h. The association of higher carbohydrate levels with improved rooting in previously dark-exposed versus non-treated cuttings indicates that increased post-darkness carbohydrate availability and allocation towards the stem base contribute to ARF under the influence of dark treatment and provide energy for cell growth subject to a rising sink intensity in the base of the cutting. Copyright 2009 Elsevier GmbH. All rights reserved.

  4. Transparent organic light-emitting diodes with different bi-directional emission colors using color-conversion capping layers

    International Nuclear Information System (INIS)

    Lee, Jonghee; Koh, Tae-Wook; Cho, Hyunsu; Schwab, Tobias; Lee, Jae-Hyun; Hofmann, Simone; Lee, Jeong-Ik; Yoo, Seunghyup

    2015-01-01

    We report a study on transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors, enabled by color-conversion organic capping layers. Starting from a transparent blue OLED with an uncapped Ag top electrode exhibiting an average transmittance of 33.9%, a 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran (DCM)-doped tris-(8-hydroxy-quinolinato)-aluminum (Alq3) capping layer is applied to achieve color-conversion from blue to orange-red on the top side while maintaining almost unchanged device transmittance. This color-conversion capping layer does not only change the color of the top side emission, but also enhances the overall device efficiency due to the optical interaction of the capping layer with the primary blue transparent OLED. Top white emission from the transparent bi-directional OLED exhibits a correlated color temperature around 6000–7000 K, with excellent color stability as evidenced by an extremely small variation in color coordinate of Δ(x,y)=(0.002, 0.002) in the forward luminance range of 100–1000 cd m −2 . At the same time, the blue emission color of bottom side is not influenced by the color conversion capping layer, which finally results in different emission colors of the two opposite sides of our transparent OLEDs. - Highlights: • We report transparent organic light-emitting diodes (OLEDs) with different bi-directional emission colors. • Transparent blue OLED with color-conversion organic capping layers (CCL) shows orange top side emission. • Top white emission exhibits a CCT around 7000 K, with excellent color stability on a driving voltage

  5. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  6. THE EFFECTS OF BIODIESEL BLENDS AND ARCO EC-DIESEL ON EMISSIONS from LIGHT HEAVY-DUTY DIESEL VEHICLES

    Energy Technology Data Exchange (ETDEWEB)

    Durbin, Thomas

    2001-08-05

    Chassis dynamometer tests were performed on 7 light heavy-duty diesel trucks comparing the emissions of a California diesel fuel with emissions from 4 other fuels: ARCO EC-diesel (EC-D) and three 20% biodiesel blends (1 yellow grease and 2 soy-based). The EC-D and the yellow grease biodiesel blend both showed significant reductions in THC and CO emissions over the test vehicle fleet. EC-D also showed reductions in PM emission rates. NOx emissions were comparable for the different fuel types over the range of vehicles tested. The soy-based biodiesel blends did not show significant or consistent emissions differences over all test vehicles. Total carbon accounted for more than 70% of the PM mass for 4 of the 5 sampled vehicles. Elemental and organic carbon ratios varied significantly from vehicle-to-vehicle but showed very little fuel dependence. Inorganic species represented a smaller portion of the composite total, ranging from 0.2 to 3.3% of the total PM. Total PAH emissions ranged from approximately 1.8 mg/mi to 67.8 mg/mi over the different vehicle/fuel combinations representing between 1.6 and 3.8% of the total PM mass.

  7. Exhaust gas emissions from various automotive fuels for light-duty vehicles. Effects on health, environment and energy utilization

    International Nuclear Information System (INIS)

    Ahlvik, P.; Brandberg, Aa.

    1999-12-01

    The main aim of the investigation has been to assess the effects on health and environment from various alternative fuels for light-duty vehicles. Effects that can be identified and quantified, such as acidification, ozone formation, cancer risk and climate change, have been of primary interest but other effects, such as respiratory diseases, have also been investigated. Data have been collected through literature surveys for subsequent calculation of the mentioned effects in different time-frames. Corrections have been used to take into consideration the influence of climate, ageing and driving pattern. Emissions generated in fuel production have also been accounted for. The most significant and important differences between the fuels have been found for effects as ozone formation cancer risk and particulate emissions. Alternative fuels, such as methanol and methane (natural gas and biogas), significantly decrease the ozone formation in comparison to petrol, while ethanol, methanol and methane are advantageous concerning cancer risk. The particulate emissions are considerably higher for diesel engines fuelled by diesel oil and RME in comparison to the other fuels. In the future, the importance of acid emissions in the fuel production will increase since the NO x and SO x emissions will decrease from the vehicles. The emissions of climate gases could be significantly reduced by using non-fossil fuels but the efficiency of the drive train is also of importance. The technical development potential for further emission reductions is considerable for all fuels but the advantage for the best fuel options will remain in the future

  8. Nitric oxide (NO) emissions from N-saturated subtropical forest soils are strongly affected by spatial and temporal variability in soil moisture

    Science.gov (United States)

    Kang, Ronghua; Dörsch, Peter; Mulder, Jan

    2016-04-01

    Subtropical forests in Southwest China have chronically high nitrogen (N) deposition. This results in high emission rates of N gasses, including N2O, NO and N2. In contrast to N2O, NO emission in subtropical China has received little attention, partly because its quantification is challenging. Here we present NO fluxes in a Masson pine-dominated headwater catchment with acrisols on mesic, well-drained hill slopes at TieShanPing (Chongqing, SW China). Measurements were conducted from July to September in 2015, using a dynamic chamber technique and a portable and highly sensitive chemiluminesence NOx analyzer (LMA-3M, Drummond Technology Inc, Canada). Mean NO fluxes as high as 120 μg N m-2 h-1 (± 56 μg N m-2 h-1) were observed at the foot of the hill slope. Mid-slope positions had intermediate NO emission rates (47 ± 17 μg N m-2 h-1), whereas the top of the hill slope showed the lowest NO fluxes (3 ± 3 μg N m-2 h-1). The magnitude of NO emission seemed to be controlled mainly by site-specific soil moisture, which was on average lower at the foot of the hill slope and in mid-slope positions than at the top of the hill slope. Rainfall episodes caused a pronounced decline in NO emission fluxes in all hill slope positions, whereas the subsequent gradual drying of the soil resulted in an increase. NO fluxes were negatively correlated with soil moisture (r2 = 0.36, p ˂ 0.05). The NO fluxes increased in the early morning, and decreased in the late afternoon, with peak emissions occurring between 2 and 3 pm. The diurnal variation of NO fluxes on mid-slope positions was positively correlated with soil temperature (r2 = 0.9, p ˂ 0.05). Our intensive measurements indicate that NO-N emissions in N-saturated subtropical forests are significant and strongly controlled by local hydrological conditions.

  9. Nitrous Oxide Emissions in a Managed Grassland are Strongly Influenced by CO2 Concentrations Across a Range of Soil Moisture Levels

    Science.gov (United States)

    Brown, Z. A.; Hovenden, M. J.; Hunt, M.

    2017-12-01

    Though the atmosphere contains less nitrous oxide (N2O, 324 ppb) than carbon dioxide (CO2, 400 ppm­), N2O has 298 times the global warming potential of CO2 on a 100-year horizon. Nitrous oxide emissions tend to be greater in moist soils because denitrification is an anaerobic process. The rising concentration of CO2 in the atmosphere reduces plant stomatal aperture, thereby slowing transpiration and water use and leading to higher soil moisture levels. Thus, the rising CO2 concentration could stimulate N2O emissions indirectly via increasing soil moisture. Further, results from field experiments in which CO2 is elevated have demonstrated nitrification is accelerated at elevated CO2 concentrations (eCO2). Hence, N2O emissions could be substantially increased by the impacts of rising CO2 concentrations on plant and ecosystem physiology. However, the scale of this impact could be influenced by the amount of water supplied through irrigation or rainfall since both nitrification and denitrification are sensitive to soil moisture. Here, we use measurements of CO2 and N2O emissions from the TasFACE2 experiment to explore the ways in which the impact of CO2 concentration on greenhouse gas emissions is influenced by water supply in a managed temperate pasture. TasFACE2 is the world's only experiment that explicitly controls soil water availability at three different CO2 concentrations. Application of chemical nitrification inhibitor severely reduces N2O flux from soils regardless of CO2 level, water treatment and time following urea application. This inhibitor reduced soil respiration in plots exposed to ambient CO2 plots but not in eCO2 plots. N2O flux is stimulated by eCO2 but not consistently among watering treatments or seasons. Soil respiration is strongly enhanced by CO2 effect regardless of watering treatment. The results demonstrate that CO2 concentration has a sustained impact on CO2 and N2O flux across a range of water availabilities in this fertilised, ryegrass

  10. Biogenic Volatile Organic Compound (BVOC) emissions from agricultural crop species: is guttation a possible source for methanol emissions following light/dark transition ?

    Science.gov (United States)

    Mozaffar, Ahsan; Amelynck, Crist; Bachy, Aurélie; Digrado, Anthony; Delaplace, Pierre; du Jardin, Patrick; Fauconnier, Marie-Laure; Schoon, Niels; Aubinet, Marc; Heinesch, Bernard

    2015-04-01

    In the framework of the CROSTVOC (CROp STress VOC) project, the exchange of biogenic volatile organic compounds (BVOCs) between two important agricultural crop species, maize and winter wheat, and the atmosphere has recently been measured during an entire growing season by using the eddy covariance technique. Because of the co-variation of BVOC emission drivers in field conditions, laboratory studies were initiated in an environmental chamber in order to disentangle the responses of the emissions to variations of the individual environmental parameters (such as PPFD and temperature) and to diverse abiotic stress factors. Young plants were enclosed in transparent all-Teflon dynamic enclosures (cuvettes) through which BVOC-free and RH-controlled air was sent. BVOC enriched air was subsequently sampled from the plant cuvettes and an empty cuvette (background) and analyzed for BVOCs in a high sensitivity Proton Transfer Reaction Mass Spectrometer (hs-PTR-MS) and for CO2 in a LI-7000 non-dispersive IR gas analyzer. Emissions were monitored at constant temperature (25 °C) and at a stepwise varying PPFD pattern (0-650 µmol m-2 s-1). For maize plants, sudden light/dark transitions at the end of the photoperiod were accompanied by prompt and considerable increases in methanol (m/z 33) and water vapor (m/z 39) emissions. Moreover, guttation droplets appeared on the sides and the tips of the leaves within a few minutes after light/dark transition. Therefore the assumption has been raised that methanol is also coming out with guttation fluid from the leaves. Consequently, guttation fluid was collected from young maize and wheat plants, injected in an empty enclosure and sampled by PTR-MS. Methanol and a large number of other compounds were observed from guttation fluid. Recent studies have shown that guttation from agricultural crops frequently occurs in field conditions. Further research is required to find out the source strength of methanol emissions by this guttation

  11. Effect of sintering temperature of Ce3+-doped Lu3Al5O12 phosphors on light emission and properties of crystal structure for white-light-emitting diodes

    Science.gov (United States)

    Koizumi, Hiroshi; Watabe, Junya; Sugiyama, Shin; Hirabayashi, Hideaki; Homma, Tetsuya

    2018-03-01

    The effect of the sintering temperature of Ce3+-doped Lu3Al5O12 (Ce-LuAG) phosphors on the emission and properties of the crystal structure was studied. A cathodoluminescence peak at 317 nm, which was assigned to lattice defects, was exhibited in addition to emission peaks at 508 and 540 nm for the Ce-LuAG phosphors. The intensities of the 317 nm emission peak for the phosphors with mean particle diameters of 5.0 and 10.0 µm formed at a low sintering temperature of 1430 °C were higher than those for the phosphors with mean particle diameters of 18.0 and 20.5 µm formed at a high sintering temperature of 1550 °C. In contrast, the electroluminescence spectra for fabricated white-light-emitting diodes (LEDs) using the phosphors revealed that the intensity of the peak at 540 nm was strong for the mean particle diameters of 18.0 and 20.5 µm. The intensity of the 540 nm peak, which is attributed to the 4f→5d transition of the Ce3+ activator, showed a dependence on the sintering temperature. The relationship between the optical properties and the lattice defects is discussed.

  12. SUZAKU OBSERVATION OF STRONG FLUORESCENT IRON LINE EMISSION FROM THE YOUNG STELLAR OBJECT V1647 ORI DURING ITS NEW X-RAY OUTBURST

    International Nuclear Information System (INIS)

    Hamaguchi, Kenji; Grosso, Nicolas; Kastner, Joel H.; Richmond, Michael; Weintraub, David A.

    2010-01-01

    The Suzaku X-ray satellite observed the young stellar object (YSO) V1647 Ori on 2008 October 8 during the new mass accretion outburst reported in 2008 August. During the 87 ks observation with a net exposure of 40 ks, V1647 Ori showed a high level of X-ray emission with a gradual decrease in flux by a factor of 5 and then displayed an abrupt flux increase by an order of magnitude. Such enhanced X-ray variability was also seen in XMM-Newton observations in 2004 and 2005 during the 2003-2005 outburst, but has rarely been observed for other YSOs. The spectrum clearly displays emission from Helium-like iron, which is a signature of hot plasma (kT ∼ 5 keV). It also shows a fluorescent iron Kα line with a remarkably large equivalent width (EW) of ∼600 eV. Such a large EW suggests that a part of the incident X-ray emission that irradiates the circumstellar material and/or the stellar surface is hidden from our line of sight. XMM-Newton spectra during the 2003-2005 outburst did not show a strong fluorescent iron Kα line, so that the structure of the circumstellar gas very close to the stellar core that absorbs and re-emits X-ray emission from the central object may have changed in between 2005 and 2008. This phenomenon may be related to changes in the infrared morphology of McNeil's nebula between 2004 and 2008.

  13. A rapid excitation-emission matrix fluorometer utilizing supercontinuum white light and acousto-optic tunable filters

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Wenbo [Imaging Unit, Integrative Oncology Department, BC Cancer Agency Research Center, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3 (Canada); Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8 (Canada); Department of Biomedical Engineering, University of British Columbia, KAIS 5500, 2332 Main Mall, Vancouver, British Columbia V6T 1Z4 (Canada); Wu, Zhenguo; Zhao, Jianhua; Lui, Harvey; Zeng, Haishan, E-mail: hzeng@bccrc.ca [Imaging Unit, Integrative Oncology Department, BC Cancer Agency Research Center, 675 West 10th Avenue, Vancouver, British Columbia V5Z 1L3 (Canada); Department of Dermatology and Skin Science, University of British Columbia, 835 West 10th Avenue, Vancouver, British Columbia V5Z 4E8 (Canada)

    2016-06-15

    Scanning speed and coupling efficiency of excitation light to optic fibres are two major technical challenges that limit the potential of fluorescence excitation-emission matrix (EEM) spectrometer for on-line applications and in vivo studies. In this paper, a novel EEM system, utilizing a supercontinuum white light source and acousto-optic tunable filters (AOTFs), was introduced and evaluated. The supercontinuum white light, generated by pumping a nonlinear photonic crystal fiber with an 800 nm femtosecond laser, was efficiently coupled into a bifurcated optic fiber bundle. High speed EEM spectral scanning was achieved using AOTFs both for selecting excitation wavelength and scanning emission spectra. Using calibration lamps (neon and mercury argon), wavelength deviations were determined to vary from 0.18 nm to −0.70 nm within the spectral range of 500–850 nm. Spectral bandwidth for filtered excitation light broadened by twofold compared to that measured with monochromatic light between 650 nm and 750 nm. The EEM spectra for methanol solutions of laser dyes were successfully acquired with this rapid fluorometer using an integration time of 5 s.

  14. The role of neutral and ionized oxygen defects in the emission of tin oxide nanocrystals for near white light application.

    Science.gov (United States)

    Kumar, Vinod; Swart, H C; Gohain, Mukut; Bezuidenhoudt, Barend C B; van Vuuren, A Janse; Lee, M; Ntwaeaborwa, O M

    2015-07-24

    Tin oxide (SnO2) nanocrystals (NCs) based phosphor was synthesized by a green chemistry microwave-assisted hydrothermal method at different reactor pressures. The x-ray diffraction analysis showed that a single rutile SnO2 phase with a tetragonal lattice structure was formed. The photoluminescence emission was measured for He-Cd laser excitation at 325 nm and it showed a broad band emission from 400 to 800 nm for all the synthesized reactor pressures. The broad emission spectra were due to the creation of various oxygen and tin defects as confirmed by x-ray photoelectron spectroscopy data. The origin of the emission in the SnO2 NCs is discussed with the help of an energy band diagram. Analysis suggests that the visible emission of SnO2 NCs is due to a transition of an electron from a level close to the conduction band edge to a deeply trapped hole in the SnO2 NCs. The NCs were found to be suitable for warm near white light emission device applications.

  15. The effects of biodiesels on semivolatile and nonvolatile particulate matter emissions from a light-duty diesel engine.

    Science.gov (United States)

    Cheng, Yuan; Li, Shao-Meng; Liggio, John; Hayden, Katherine; Han, Yuemei; Stroud, Craig; Chan, Tak; Poitras, Marie-Josée

    2017-11-01

    Semivolatile organic compounds (SVOCs) represent a dominant category of secondary organic aerosol precursors that are increasingly included in air quality models. In the present study, an experimental system was developed and applied to a light-duty diesel engine to determine the emission factors of particulate SVOCs (pSVOCs) and nonvolatile particulate matter (PM) components at dilution ratios representative of ambient conditions. The engine was tested under three steady-state operation modes, using ultra-low-sulfur diesel (ULSD), three types of pure biodiesels and their blends with ULSD. For ULSD, the contribution of pSVOCs to total particulate organic matter (POM) mass in the engine exhaust ranged between 21 and 85%. Evaporation of pSVOCs from the diesel particles during dilution led to decreases in the hydrogen to carbon ratio of POM and the PM number emission factor of the particles. Substituting biodiesels for ULSD could increase pSVOCs emissions but brought on large reductions in black carbon (BC) emissions. Among the biodiesels tested, tallow/used cooking oil (UCO) biodiesel showed advantages over soybean and canola biodiesels in terms of both pSVOCs and nonvolatile PM emissions. It is noteworthy that PM properties, such as particle size and BC mass fraction, differed substantially between emissions from conventional diesel and biodiesels. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Super RLuc8: A novel engineered Renilla luciferase with a red-shifted spectrum and stable light emission.

    Science.gov (United States)

    Rahnama, Somaieh; Saffar, Behnaz; Kahrani, Zahra Fanaei; Nazari, Mahboobeh; Emamzadeh, Rahman

    2017-01-01

    Renilla luciferase is a bioluminescent enzyme which is broadly used as a reporter protein in molecular biosensors. In this study, a novel luciferase with desired light emission wavelength and thermostability is reported. The results indicated that the new luciferase, namely super RLuc8, had a red-shifted spectrum and showed stable light emission. Super RLuc8 showed a 10-fold (p-value=0.0084) increase in the thermostability at 37°C after 20min incubation, in comparison to the native enzyme. The optimum temperature of the mutant increased from 30 to 37°C. Molecular dynamics simulation analysis indicated that the increased thermostability was most probably caused by a better structural compactness and more local rigidity in the regions out of the emitter site. Copyright © 2016 Elsevier Inc. All rights reserved.

  17. Rear surface light emission measurements from laser-produced shock waves in clear and Al-coated polystyrene targets

    Science.gov (United States)

    McLean, E. A.; Deniz, A. V.; Schmitt, A. J.; Stamper, J. A.; Obenschain, S. P.; Lehecka, T.; Mostovych, A. N.; Seely, J.

    1999-08-01

    The Nike KrF laser, with its very uniform focal distributions, has been used at intensities near 10 14 W/cm 2 to launch shock waves in polystyrene targets. The rear surface visible light emission differed between clear polystyrene (CH) targets and targets with a thin (125 nm) Al coating on the rear side. The uncoated CH targets showed a relatively slowly rising emission followed by a sudden fall when the shock emerges, while the Al-coated targets showed a rapid rise in emission when the shock emerges followed by a slower fall, allowing an unambiguous determination of the time the shock arrived at the rear surface. A half-aluminized target allowed us to observe this difference in a single shot. The brightness temperature of both the aluminized targets and the non-aluminized targets was slightly below but close to rear surface temperature predictions of a hydrodynamic code. A discussion of preheat effects is given.

  18. Optical spectroscopy, energy upconversion, and white-light emission characteristics of erbium-doped calcium fluoride crystal

    Science.gov (United States)

    Culp, Mical; Edwards, Vernessa M.; Reddy, Bommareddi Rami

    2017-04-01

    Absorption spectrum of Er3+-doped CaF2 revealed absorption peaks at 255, 365, 379, 407, 441, 449, 487, 522, 539, 652, and 798 nm. When the sample was excited with an 802-nm near-infrared laser, it revealed emissions at 390, 415, 462, 555, 665, and 790 nm due to stepwise excitation and energy transfer upconversion processes. The absorption and emission peaks are identified with Er3+ spectral transitions. The sample color appears to be either white or green under near-infrared laser excitation. Emission color was found to be dependent on the pump laser wavelength used and laser power. Excitation spectral recordings were made by tuning the pump laser wavelength. Excited state lifetimes are measured to analyze the data. Color coordinates and color temperatures are measured for 802- and 405-nm laser excitations. Our studies indicate that this sample is useful for solid-state lighting applications.

  19. RE-EVALUATING WASP-12b: STRONG EMISSION AT 2.315 μm, DEEPER OCCULTATIONS, AND AN ISOTHERMAL ATMOSPHERE

    International Nuclear Information System (INIS)

    Crossfield, Ian J. M.; Barman, Travis; Hansen, Brad M. S.; Tanaka, Ichi; Kodama, Tadayuki

    2012-01-01

    We revisit the atmospheric properties of the extremely hot Jupiter WASP-12b in light of several new developments. First, we present new narrowband (2.315 μm) secondary eclipse photometry, which exhibits a planet/star flux ratio of 0.45% ± 0.06%, corresponding to a brightness temperature of 3640 ± 230 K; second, recent Spitzer/Infrared Array Camera and Hubble Space Telescope/Wide Field Camera 3 observations; and third, a recently observed star only 1'' from WASP-12, which has diluted previous observations and which we further characterize here. We correct past WASP-12b eclipse measurements for the presence of this object, and we revisit the interpretation of WASP-12b's dilution-corrected emission spectrum. The resulting planetary emission spectrum is well approximated by a blackbody, and consequently our primary conclusion is that the planet's infrared photosphere is nearly isothermal. Thus, secondary eclipse spectroscopy is relatively ill suited to constrain WASP-12b's atmospheric abundances, and transmission spectroscopy may be necessary to achieve this goal.

  20. Insight into the strong aggregation-induced emission of low-conjugated racemic C6-unsubstituted tetrahydropyrimidines through crystal-structure-property relationship of polymorphs.

    Science.gov (United States)

    Zhu, Qiuhua; Zhang, Yilin; Nie, Han; Zhao, Zujin; Liu, Shuwen; Wong, Kam Sing; Tang, Ben Zhong

    2015-08-01

    Racemic C6-unsubstituted tetrahydropyrimidines (THPs) are a series of fluorophores with a strong aggregation-induced emission (AIE) effect. However, they do not possess the structural features of conventional AIE compounds. In order to understand their AIE mechanism, here, the influences of the molecular packing mode and the conformation on the optical properties of THPs were investigated using seven crystalline polymorphs of three THPs ( 1-3 ). The racemic THPs 1-3 have low-conjugated and highly flexible molecular structures, and hence show practically no emission in different organic solvents. However, the fluorescence quantum yields of their polymorphs are up to 93%, and the maximum excitation ( λ ex ) and emission ( λ em ) wavelengths of the polymorphs are long at 409 and 484 nm, respectively. Single-crystal structures and theoretical calculation of the HOMOs and LUMOs based on the molecular conformations of these polymorphs indicate that the polymorphs with the shortest λ ex and λ em values possess a RS -packing mode ( R - and S -enantiomers self-assemble as paired anti-parallel lines) and a more twisted conformation without through-space conjugation between the dicarboxylates, but the polymorphs with longer λ ex and λ em values adopt a RR / SS -packing mode ( R - and S -enantiomers self-assemble as unpaired zigzag lines) and a less twisted conformation with through-space conjugation between the dicarboxylates. The molecular conformations of 1-3 in all these polymorphs are stereo and more twisted than those in solution. Although 1-3 are poorly conjugated, the radiative rate constants ( k r ) of their polymorphs are as large as conventional fluorophores (0.41-1.03 × 10 8 s -1 ) because of improved electronic conjugation by both through-bond and through-space interactions. Based on the obtained results, it can be deduced that the strong AIE arises not only from the restriction of intramolecular motion but also from enhanced electronic coupling and

  1. On-road assessment of light duty vehicles in Delhi city: Emission factors of CO, CO2 and NOX

    Science.gov (United States)

    Jaiprakash; Habib, Gazala

    2018-02-01

    This study presents the technology based emission factors of gaseous pollutants (CO, CO2, and NOX) measured during on-road operation of nine passenger cars of diesel, gasoline, and compressed natural gas (CNG). The emissions from two 3-wheelers, and three 2-wheelers were measured by putting the vehicles on jacks and operating them according to Modified Indian Driving Cycle (MIDC) at no load condition. The emission factors observed in the present work were significantly higher than values reported from dynamometer study by Automotive Research Association of India (ARAI). Low CO (0.34 ± 0.08 g km-1) and high NOX (1.0 ± 0.4 g km-1) emission factors were observed for diesel passenger cars, oppositely high CO (2.2 ± 2.6 g km-1) and low NOX (1.0 ± 1.6 g km-1) emission factors were seen for gasoline powered cars. The after-treatment technology in diesel vehicles was effective in CO reduction. While the use of turbocharger in diesel vehicles to generate high combustion temperature and pressure produces more NOx, probably which may not be effectively controlled by after-treatment device. The after-treatment devices in gasoline powered Post-2010, Post-2005 vehicles can be acclaimed for reduced CO emissions compared to Post-2000 vehicles. This work presents a limited data set of emission factors from on-road operations of light duty vehicles, this limitation can be improved by further measurements of emissions from similar vehicles.

  2. Enhanced Extraction of Silicon-Vacancy Centers Light Emission Using Bottom-Up Engineered Polycrystalline Diamond Photonic Crystal Slabs.

    Science.gov (United States)

    Ondič, Lukáš; Varga, Marian; Hruška, Karel; Fait, Jan; Kapusta, Peter

    2017-03-28

    Silicon vacancy (SiV) centers are optically active defects in diamond. The SiV centers, in contrast to nitrogen vacancy (NV) centers, possess narrow and efficient luminescence spectrum (centered at ≈738 nm) even at room temperature, which can be utilized for quantum photonics and sensing applications. However, most of light generated in diamond is trapped in the material due to the phenomenon of total internal reflection. In order to overcome this issue, we have prepared two-dimensional photonic crystal slabs from polycrystalline diamond thin layers with high density of SiV centers employing bottom-up growth on quartz templates. We have shown that the spectral overlap between the narrow light emission of the SiV centers and the leaky modes extracting the emission into almost vertical direction (where it can be easily detected) can be obtained by controlling the deposition time. More than 14-fold extraction enhancement of the SiV centers photoluminescence was achieved compared to an uncorrugated sample. Computer simulation confirmed that the extraction enhancement originates from the efficient light-matter interaction between light emitted from the SiV centers and the photonic crystal slab.

  3. The relationship between visible light emission and species fraction of the hydrogen ion beams extracted from 2.45 GHz microwave discharge

    CERN Document Server

    Cortázar, O D; Tarvainen, O; Kalvas, T; Koivisto, H

    2015-01-01

    The relationship between Balmer-α and Fulcher-band emissions with extracted H +, H+2 , and H+3 ions is demonstrated for a 2.45 GHz microwave discharge. Ion mass spectra and optical measurements of Balmer-α and Fulcher-band emissions have been obtained with a Wien Filter having an optical view-port on the plasma chamber axis. The beam of approximately 1 mA is analyzed for different plasma conditions simultaneously with the measurement of light emissions both with temporal resolution. The use of visible light emissions as a valuable diagnostic tool for monitoring the species fraction of the extracted beams is proposed.

  4. Time-resolved pulse-counting lock-in detection of laser induced fluorescence in the presence of a strong background emission

    International Nuclear Information System (INIS)

    Pelissier, B.; Sadeghi, N.

    1996-01-01

    We describe a time-resolved pulse-counting system well adapted for the detection of continuous laser induced fluorescence (LIF) signals in repetitive phenomena, when a strong background emission is present. It consists of 256 channels coupled to a first in first out memory and interfaced to a 486 DX 33 PC, for data storage. It accepts time-averaged count rates up to 450 kcount/s. Time between channels can be set from 12.5 ns to several μs and the dead time between two consecutive cycles of the physical phenomena is less than 20 ns. In phase with a chopper, which modulates the laser beam, it adds the observed photon signal to the channel memories when the beam is on and substracts it when the beam is stopped, acting like a lock-in amplifier which detect only the modulated part of the signal. The minimum detectivity on the LIF signal is only limited by the shot noise of the plasma induced emission signal. As an application, we studied the time variation of the Ar + *( 2 G 9/2 ) metastable ions, detected by LIF, in two types of plasmas. Their radiative lifetime and collisional quenching frequencies were deduced from their decay rate in the afterglow of a pulsed Helicon reactor. We also observed the evolution of their density in a 455 kHz capacitively coupled argon discharge. copyright 1996 American Institute of Physics

  5. Time-resolved pulse-counting lock-in detection of laser induced fluorescence in the presence of a strong background emission

    Science.gov (United States)

    Pelissier, B.; Sadeghi, N.

    1996-10-01

    We describe a time-resolved pulse-counting system well adapted for the detection of continuous laser induced fluorescence (LIF) signals in repetitive phenomena, when a strong background emission is present. It consists of 256 channels coupled to a first in first out memory and interfaced to a 486 DX 33 PC, for data storage. It accepts time-averaged count rates up to 450 kcount/s. Time between channels can be set from 12.5 ns to several μs and the dead time between two consecutive cycles of the physical phenomena is less than 20 ns. In phase with a chopper, which modulates the laser beam, it adds the observed photon signal to the channel memories when the beam is on and substracts it when the beam is stopped, acting like a lock-in amplifier which detect only the modulated part of the signal. The minimum detectivity on the LIF signal is only limited by the shot noise of the plasma induced emission signal. As an application, we studied the time variation of the Ar+*(2G9/2) metastable ions, detected by LIF, in two types of plasmas. Their radiative lifetime and collisional quenching frequencies were deduced from their decay rate in the afterglow of a pulsed Helicon reactor. We also observed the evolution of their density in a 455 kHz capacitively coupled argon discharge.

  6. Emissions from light duty gasoline vehicles operating on low blend ethanol gasoline and E85

    Science.gov (United States)

    Graham, Lisa A.; Belisle, Sheri L.; Baas, Cara-Lynn

    The results of two recent vehicle emission studies are described in this paper, along with a statistical analysis of the changes in tailpipe emissions due to the use of ethanol that includes the results from these two studies in combination with results from other literature reports. The first study evaluates the effect of two low blend ethanol gasolines (E10, E20) on tailpipe and evaporative emissions from three multi-port fuel injection vehicles and one gasoline direct injection vehicle at two different test temperatures. The second study evaluates the differences in tailpipe emissions and fuel consumptions of paired flexible fuel and conventional gasoline vehicles operating on California RFG Phase 2 and/or E85 fuels at 20 °C. The vehicles were tested over the four-phase FTP or UDDS and US06 driving cycles. Tailpipe emissions were characterized for criteria pollutants (CO, NO X, NMHC, NMOG), greenhouse gases (CO 2, CH 4, N 2O), and a suite of unregulated emissions including important air toxics (benzene, 1,3-butadiene, formaldehyde, acetaldehyde, acrolein), and ozone reactivity. In the low blend ethanol study, evaporative emissions were quantified and characterized for NMHC. While contradicting, results can be seen among the various literature reports and with these two new studies, the statistical analyses of the aggregated data offers much clearer pictures of the changes in tailpipe emissions that may be expected using either low blend ethanol gasoline (E10) or E85. The results of the statistical analysis suggest that the use of E10 results in statistically significant decreases in CO emissions (-16%); statistically significant increases in emissions of NMHC (9%), NMOG (14%), acetaldehyde (108%), 1,3-butadiene (16%), and benzene (15%); and no statistically significant changes in NO X, CO 2, CH 4, N 2O or formaldehyde emissions. The statistical analysis suggests that the use of E85 results in statistically significant decreases in emissions of NO X (-45%), NMHC

  7. Enhanced Emission by Accumulated Charges at Organic/Metal Interfaces Generated during the Reverse Bias of Organic Light Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Soichiro Nozoe

    2017-10-01

    Full Text Available A high frequency rectangular alternating voltage was applied to organic light emitting diodes (OLEDs with the structure ITO/TPD/Alq3/Al and ITO/CoPc/Alq3/Al, where ITO is indium-tin-oxide, TPD is 4,4′-bis[N-phenyl-N-(m-tolylamino]biphenyl, CoPc is cobalt phthalocyanine, and Alq3 is Tris(8-quinolinolatoaluminum, and the effect on emission of the reverse bias was examined. The results reveal that the emission intensity under an alternating reverse-forward bias is greater than that under an alternating zero-forward bias. The difference in the emission intensity (∆I increased both for decreasing frequency and increasing voltage level of the reverse bias. In particular, the change in emission intensity was proportional to the voltage level of the reverse bias given the same frequency. To understand ΔI, this paper proposes a model in which an OLED works as a capacitor under reverse bias, where positive and negative charges accumulate on the metal/organic interfaces. In this model, the emission enhancement that occurs during the alternating reverse-forward bias is rationalized as a result of the charge accumulation at the organic/metal interfaces during the reverse bias, which possibly modulates the vacuum level shifts at the organic/metal interfaces to reduce both the hole injection barrier at the organic/ITO interface and the electron injection barrier at the organic/Al interface under forward bias.

  8. Time-resolved light emission of a, c, and r-cut sapphires shock-compressed to 65 GPa

    Science.gov (United States)

    Liu, Q. C.; Zhou, X. M.

    2018-04-01

    To investigate light emission and dynamic deformation behaviors, sapphire (single crystal Al2O3) samples with three crystallographic orientations (a, c, and r-cut) were shock-compressed by the planar impact method, with final stress ranges from 47 to 65 GPa. Emission radiance and velocity versus time profiles were simultaneously measured with a fast pyrometer and a Doppler pin system in each experiment. Wave profile results show anisotropic elastic-plastic transitions, which confirm the literature observations. Under final shock stress of about 52 GPa, lower emission intensity is observed in the r-cut sample, in agreement with the previous report in the literature. When final shock stress increases to 57 GPa and 65 GPa, spectral radiance histories of the r-cut show two stages of distinct features. In the first stage, the emission intensity of r-cut is lower than those of the other two, which agrees with the previous report in the literature. In the second stage, spectral radiance of r-cut increases with time at much higher rate and it finally peaks over those of the a and c-cut. These observations (conversion of intensified emission in the r-cut) may indicate activation of a second slip system and formation of shear bands which are discussed with the resolved shear stress calculations for the slip systems in each of the three cuts under shock compression.

  9. On the primary emission of formic acid from light duty gasoline vehicles and ocean-going vessels

    Science.gov (United States)

    Crisp, Timia A.; Brady, James M.; Cappa, Christopher D.; Collier, Sonya; Forestieri, Sara D.; Kleeman, Michael J.; Kuwayama, Toshihiro; Lerner, Brian M.; Williams, Eric J.; Zhang, Qi; Bertram, Timothy H.

    2014-12-01

    We present determinations of fuel-based emission factors for formic acid (EFHCOOH) from light duty gasoline vehicles (LDGVs) and in-use ocean-going vessels. Emission ratios, from which the emission factors were derived, were determined from LDGVs through measurement of HCOOH and carbon dioxide (CO2) in the exhaust of a fleet of eight LDGVs driven under the California Unified Cycle at the California Air Resources Board's Haagen-Smit Laboratory. Emission ratios from in-use ocean-going vessels were determined through direct measurement of HCOOH and CO2 in ship plumes intercepted by the R/V Atlantis during the 2010 California Research at the Nexus of Air Quality and Climate Change (CalNex) campaign within 24 nautical miles of the California coast. The eight car fleet average EFHCOOH was 0.94 ± 0.32 (1σ) and 0.57 ± 0.18 mg (kg fuel)-1 for the cold start and hot running phases of the drive cycle, respectively. This difference suggests that catalytic converter performance and the air/fuel equivalence ratio are important metrics contributing to EFHCOOH. EFHCOOH was determined to be 1.94 ± 1.06 mg (kg fuel)-1 for a single diesel vehicle driven under highway driving conditions, higher on average than any individual LDGV tested. In comparison, HCOOH primary emissions from in-use ocean-going vessels were substantially larger, averaging 20.89 ± 8.50 mg (kg fuel)-1. On a global scale, HCOOH primary emissions from fossil fuel combustion are likely to be insignificant relative to secondary production mechanisms, however primary emissions may contribute more significantly on a finer, regional scale in urban locations.

  10. Spontaneous emission of a cesium atom near a nanofiber: Efficient coupling of light to guided modes

    International Nuclear Information System (INIS)

    Le Kien, Fam; Hakuta, K.; Dutta Gupta, S.; Balykin, V.I.

    2005-01-01

    We study the spontaneous emission of a cesium atom in the vicinity of a subwavelength-diameter fiber. We show that the confinement of the guided modes and the degeneracy of the excited and ground states substantially affect the spontaneous emission process. We demonstrate that different magnetic sublevels have different decay rates. When the fiber radius is about 200 nm, a significant fraction (up to 28%) of spontaneous emission by the atom can be channeled into guided modes. Our results may find applications for developing nanoprobes for atoms and efficient couplers for subwavelength-diameter fibers

  11. Strong energy-momentum dispersion of phonon-dressed carriers in the lightly doped band insulator SrTiO3

    International Nuclear Information System (INIS)

    Meevasana, W; Chen, C-C; He, R H; Mo, S-K; Shen, Z-X; Zhou, X J; Moritz, B; Lu, D H; Moore, R G; Devereaux, T P; Fujimori, S-I; Baumberger, F; Van der Marel, D; Nagaosa, N; Zaanen, J

    2010-01-01

    Much progress has been made recently in the study of the effects of electron-phonon (el-ph) coupling in doped insulators using angle-resolved photoemission (ARPES), yielding evidence for the dominant role of el-ph interactions in underdoped cuprates. As these studies have been limited to doped Mott insulators, the important question arises as to how this compares with doped band insulators where similar el-ph couplings should be at work. The archetypical case is that of perovskite SrTiO 3 (STO), well known for its giant dielectric constant of 10 000 at low temperatures, exceeding that of La 2 CuO 4 by a factor of 500. Based on this fact, it has been suggested that doped STO should be the archetypical bipolaron superconductor. Here we report an ARPES study from high-quality surfaces of lightly doped STO. In comparison to lightly doped Mott insulators, we find the signatures of only moderate el-ph coupling; a dispersion anomaly associated with the low-frequency optical phonon with a λ ' ∼0.3 and an overall bandwidth renormalization suggesting an overall λ ' ∼0.7 coming from the higher frequency phonons. Furthermore, we find no clear signatures of the large pseudogap or small-polaron phenomena. These findings demonstrate that a large dielectric constant itself is not a good indicator of el-ph coupling and highlight the unusually strong effects of the el-ph coupling in doped Mott insulators.

  12. Tailpipe emissions and engine performance of a light-duty diesel engine operating on petro- and bio-diesel fuel blends.

    Science.gov (United States)

    2014-06-01

    This report summarizes the experimental apparatus developed in the Transportation Air Quality Laboratory (TAQ Lab) at the University of Vermont to compare light-duty diesel engine performance and exhaust emissions when operating on petroleum diesel (...

  13. Comments on the Joint Proposed Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards

    Energy Technology Data Exchange (ETDEWEB)

    Wenzel, Tom [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2009-10-27

    Tom Wenzel of Lawrence Berkeley National Laboratory comments on the joint rulemaking to establish greenhouse gas emission and fuel economy standards for light-duty vehicle, specifically on the relationship between vehicle weight and vehicle safety.

  14. Size dependence of silica nanospheres embedded in 385 nm ultraviolet light-emitting diodes on a far-field emission pattern.

    Science.gov (United States)

    Park, Young Jae; Han, Nam; Ryu, Beo Deul; Han, Min; Ko, Kang Bok; Cuong, Tran Viet; Cho, Jaehee; Suh, Eun-Kyung; Hong, Chang-Hee

    2014-10-20

    We demonstrate that the use of silica nanospheres (SNs) with sizes close to the emission wavelength of light-emitting diodes (LEDs) can enhance the light output power and manipulate the far-field emission pattern. Near-ultraviolet (NUV)-LEDs grown on a patterned sapphire substrate embedded with 300 nm SNs show a three times higher light output power than that without SNs, when measured through the top side. For far-field emission measurements, the LEDs embedded with 300 nm SNs show the significant increase of front emission due to the improved crystal quality of epitaxial films as well as the increase of Mie scattering effect of SNs. These experimental results indicate the important role of the size of embedded SNs in enhancing the light output power for NUV-LEDs.

  15. Color-tunable and stable-efficiency white organic light-emitting diode fabricated with fluorescent-phosphorescent emission layers

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Su-Hua, E-mail: shya@cc.kuas.edu.tw; Shih, Po-Jen; Wu, Wen-Jie; Huang, Yi-Hua

    2013-10-15

    White organic light emitting diodes (OLEDs) were fabricated for color-tunable lighting applications. Fluorescent and phosphorescent hybrid emission layers (EMLs) were used to enhance the luminance and stability of the devices, which have blue-EML/CBP interlayer/green-EML/phosphorescent-sensitized-EML/red-EML structures. The influence of the composition and structure of the EMLs on the electroluminescence properties of the devices were investigated from the viewpoint of their emission spectra. The possible exciton harvesting, diffusion, transport, and annihilation processes occurring in the EMLs were also evaluated. A maximum luminance intensity of 7400 cd/m{sup 2} and a highly stable current efficiency of 3.2 cd/A were obtained. Good color tunability was achieved for the white OLEDs; the chromatic coordinates linearly shifted from pure white (0.300, 0.398) to cold white (0.261, 0.367) when the applied voltage was varied from 10 to 14 V. -- Highlights: • Exciton harvesting, diffusion, transport, and annihilation processes were evaluated. • The electroluminescence properties were investigated from the viewpoint of the emission spectra. • Good color tunability and stable-efficiency were achieved for the white OLEDs.

  16. Readout of scintillator light with avalanche photodiodes for positron emission tomography

    International Nuclear Information System (INIS)

    Chen, Ruru; Fremout, A.; Tavernier, S.; Bruyndonckx, P.; Clement, D.; Loude, J.-F.; Morel, C.

    1999-01-01

    The noise properties and other relevant characteristics of avalanche photodiodes have been investigated with the perspective of replacing photomultiplier tubes in positron emission tomography. It is clearly demonstrated that they are a valid alternative to photomultiplier tubes in this application

  17. Effects of Cold Temperature and Ethanol Content on VOC Emissions from Light-Duty Gasoline Vehicles

    Data.gov (United States)

    U.S. Environmental Protection Agency — Supporting information Table S6 provides emission rates in g/km of volatile organic compounds measured from gasoline vehicle exhaust during chassis dynamometer...

  18. Light particle emission measurements in heavy ion reactions. Final report, June 1, 1981-May 31, 1984

    International Nuclear Information System (INIS)

    Petitt, G.A.

    1984-01-01

    Progress in instrumentation development reported includes improvements in the design of position sensitive neutron detectors, design of a thin-walled, spherical, aluminum target chamber, and use of thin silicon detectors to detect and identify evaporation residues from fusion reactions. The problem of the short lifetime of evaporation residue detectors is addressed by using a pair of large area, multi-wire proportional counters followed by a thin sheet of plastic scintillator. Neutron emission associated with fission has been studied, as well as nonequilibrium emission associated with inelastic products and evaporation residue. An experiment was performed to study neutron emission associated with fission and fission-like events in the case of the Er composite system. Other work in progress includes neutron emissions from the C + Gd and Ne + Nd reactions. 9 refs

  19. 78 FR 34375 - Proposed Information Collection Request; Comment Request; Exhaust Emissions of Light-Duty...

    Science.gov (United States)

    2013-06-07

    ... respond, including through the use of appropriate automated electronic, mechanical, or other technological... be voluntary. The target population for the project will include light-duty cars and trucks certified... Numbers: 2363.02. Respondents/affected entities: private owners of light-duty cars and trucks. Respondent...

  20. Light charged particle emission in heavy-ion reactions – What have ...

    Indian Academy of Sciences (India)

    Light charged particles; heavy-ion induced reactions; particle spectra and angular distri- butions; reaction mechanisms. ... 6–8 MeV/A. A typical light charged particle spectrum clearly reveals several aspects: the evaporation peak at low .... will alter the shapes of the particle spectra and the effect being more for the alphas.

  1. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  2. The future of emissions trading in light of the acid rain experience

    International Nuclear Information System (INIS)

    McLean, B.J.; Rico, R.

    1995-01-01

    The idea of emissions trading was developed more than two decades ago by environmental economists eager to provide new ideas for how to improve the efficiency of environmental protection. However, early emissions trading efforts were built on the historical open-quotes command and controlclose quotes infrastructure which has dominated U.S. environmental protection until today. The open-quotes command and controlclose quotes model initially had advantages that were of a very pragmatic character: it assured large pollution reductions in a time when large, cheap reductions were available and necessary; and it did not require a sophisticated government infrastructure. Within the last five years, large-scale emission trading programs have been successfully designed and started that are fundamentally different from the earlier efforts, creating a new paradigm for environmental control just when our understanding of environmental problems is changing as well. The purpose of this paper is to focus on the largest national-scale program--the Acid Rain Program--and from that experience, forecast when emission trading programs may be headed based on our understanding of the factors currently influencing environmental management. The first section of this paper will briefly review the history of emissions trading programs, followed by a summary of the features of the Acid Rain Program, highlighting those features that distinguish it from previous efforts. The last section addresses the opportunities for emissions trading (and its probable future directions)

  3. Light Converting Inorganic Phosphors for White Light-Emitting Diodes

    Directory of Open Access Journals (Sweden)

    Chiao-Wen Yeh

    2010-03-01

    Full Text Available White light-emitting diodes (WLEDs have matched the emission efficiency of florescent lights and will rapidly spread as light source for homes and offices in the next 5 to 10 years. WLEDs provide a light element having a semiconductor light emitting layer (blue or near-ultraviolet (nUV LEDs and photoluminescence phosphors. These solid-state LED lamps, rather than organic light emitting diode (OLED or polymer light-emitting diode (PLED, have a number of advantages over conventional incandescent bulbs and halogen lamps, such as high efficiency to convert electrical energy into light, reliability and long operating lifetime. To meet with the further requirement of high color rendering index, warm light with low color temperature, high thermal stability and higher energy efficiency for WLEDs, new phosphors that can absorb excitation energy from blue or nUV LEDs and generate visible emissions efficiently are desired. The criteria of choosing the best phosphors, for blue (450-480 nm and nUV (380-400 nm LEDs, strongly depends on the absorption and emission of the phosphors. Moreover, the balance of light between the emission from blue-nUV LEDs and the emissions from phosphors (such as yellow from Y3Al5O12:Ce3+ is important to obtain white light with proper color rendering index and color temperature. Here, we will review the status of phosphors for LEDs and prospect the future development.

  4. Effect of curing light emission spectrum on the nanohardness and elastic modulus of two bulk-fill resin composites.

    Science.gov (United States)

    Issa, Yaser; Watts, David C; Boyd, Daniel; Price, Richard B

    2016-04-01

    To determine the nanohardness and elastic moduli of two bulk-fill resin based composites (RBCs) at increasing depths from the surface and increasing distances laterally from the center after light curing. Two bulk-fill dental RBCs: Tetric EvoCeram Bulk Fill (TECBF) and Filtek Bulk Fill Flowable (FBFF) were light cured in a metal mold with a 6mm diameter and a 10mm long semi-circular notch. The RBCs were photo-polymerized for 10s using a light emitting diode (LED) Bluephase Style curing light, with the original light probe that lacked the homogenizer. This light has two blue light and one violet light LED emitters. By changing the probe orientation over the mold, the light output from only two LEDs reached the RBC. Measurements were made using: (i) the light from one violet and one blue LED, and (ii) the light from the two blue LEDs. Five specimens of each RBC were made using each LED orientation (total 20 specimens). Specimens were then stored in the dark at 37°C for 24h. Fifty indents were made using an Agilent G200 nanoindentor down to 4mm from the surface and 2.5mm right and left of the centerline. The results were analyzed (alpha=0.05) using multiple paired-sample t-tests, ANOVA, Bonferroni post-hoc tests, and Pearson correlations. The elastic modulus and nanohardness varied according to the depth and the distance from the centerline. For TECBF, no significant difference was found between the spatial variations in the elastic modulus or hardness values when violet-blue or blue-blue LEDs were used. For FBFF, the elastic modulus and nanohardness on the side exposed to the violet emitter were significantly less than the side exposed to the blue emitter. A strong correlation between nanohardness and elastic modulus was found in all groups (r(2)=0.9512-0.9712). Resin polymerization was not uniform throughout the RBC. The nanohardness and elastic modulus across two RBC materials were found to decline differently according to the orientation of the violet and blue

  5. In situ observation of modulated light emission of fiber fuse synchronized with void train over hetero-core splice point.

    Directory of Open Access Journals (Sweden)

    Shin-ichi Todoroki

    Full Text Available BACKGROUND: Fiber fuse is a process of optical fiber destruction under the action of laser radiation, found 20 years ago. Once initiated, opical discharge runs along the fiber core region to the light source and leaves periodic voids whose shape looks like a bullet pointing the direction of laser beam. The relation between damage pattern and propagation mode of optical discharge is still unclear even after the first in situ observation three years ago. METHODOLOGY/PRINCIPAL FINDINGS: Fiber fuse propagation over hetero-core splice point (Corning SMF-28e and HI 1060 was observed in situ. Sequential photographs obtained at intervals of 2.78 micros recorded a periodic emission at the tail of an optical discharge pumped by 1070 nm and 9 W light. The signal stopped when the discharge ran over the splice point. The corresponding damage pattern left in the fiber core region included a segment free of periodicity. CONCLUSIONS: The spatial modulation pattern of the light emission agreed with the void train formed over the hetero-core splice point. Some segments included a bullet-shaped void pointing in the opposite direction to the laser beam propagation although the sequential photographs did not reveal any directional change in the optical discharge propagation.

  6. Control of a White Organic Light Emitting Diode emission parameters using a single doped RGB active layer

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, D. [Departamento de Ciência dos Materiais e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Campus da Caparica, 2829-516 Caparica (Portugal); Pinto, A.; Califórnia, A.; Gomes, J. [CeNTI – Centro de Nanotecnologia, Materiais Técnicos, Funcionais e Inteligentes, Rua Fernando Mesquita 2785, 4760-034 Vila Nova de Famalicão (Portugal); Pereira, L., E-mail: luiz@ua.pt [Departmento de Física e i3N – Instituto de Nanoestruturas, Nanomodelação e Nanofabricação, Universidade de Aveiro, 3810-193 Aveiro (Portugal)

    2016-09-15

    Highlights: • A simple WOLED for Solid State Lighting is proposed with high color stability. • Energy transfer and electroluminescence dynamics of a single RGB layer for WOLEDs. • White shade modulation and stability over large emitting areas and applied voltages. - Abstract: Solid State Lighting technologies based on Organic Light Emitting Diodes, became an interesting focus due to their unique properties. The use of a unique RGB active layer for white emission, although simple in theory, shows difficulty to stabilize both CIE coordinates and color modulation. In this work, a WOLED using a simple RGB layer, was developed achieving a high color stability and shade modulation. The RGB matrix comprises a blue host material NPB, doped with two guests, a green (Coumarin 153) and a red (DCM1) in low concentrations. The RGB layer carrier dynamics allows for the white emission in low device complexity and high stability. This was also shown independent of the white shade, obtained through small changes in the red dopant resulting in devices ranging from warm to cool white i.e. an easy color tuning. A detailed analysis of the opto-electrical behavior is made.

  7. Control of a White Organic Light Emitting Diode emission parameters using a single doped RGB active layer

    International Nuclear Information System (INIS)

    Pereira, D.; Pinto, A.; Califórnia, A.; Gomes, J.; Pereira, L.

    2016-01-01

    Highlights: • A simple WOLED for Solid State Lighting is proposed with high color stability. • Energy transfer and electroluminescence dynamics of a single RGB layer for WOLEDs. • White shade modulation and stability over large emitting areas and applied voltages. - Abstract: Solid State Lighting technologies based on Organic Light Emitting Diodes, became an interesting focus due to their unique properties. The use of a unique RGB active layer for white emission, although simple in theory, shows difficulty to stabilize both CIE coordinates and color modulation. In this work, a WOLED using a simple RGB layer, was developed achieving a high color stability and shade modulation. The RGB matrix comprises a blue host material NPB, doped with two guests, a green (Coumarin 153) and a red (DCM1) in low concentrations. The RGB layer carrier dynamics allows for the white emission in low device complexity and high stability. This was also shown independent of the white shade, obtained through small changes in the red dopant resulting in devices ranging from warm to cool white i.e. an easy color tuning. A detailed analysis of the opto-electrical behavior is made.

  8. Observations and models of emissions of volatile terpenoid compounds from needles of ponderosa pine trees growing in situ: control by light, temperature and stomatal conductance

    Energy Technology Data Exchange (ETDEWEB)

    Harley, Peter; Eller, Allyson; Guenther, Alex; Monson, Russell K.

    2014-07-12

    Terpenoid emissions from ponderosa pine (Pinus ponderosa subsp. scopulorum) were measured in Colorado, USA over two growing seasons to evaluate the role of incident light, needle temperature and stomatal conductance in controlling emissions of 2-methyl-3-buten-2-ol (MBO) and several monoterpenes. MBO was the dominant daylight terpenoid emission, comprising on average 87% of the total flux, and diurnal variations were largely determined by light and temperature. During daytime, oxygenated monoterpenes (especially linalool) comprised up to 75% of the total monoterpenoid flux from needles. A significant fraction of monoterpenoid emissions was light dependent and 13CO2 labeling studies confirmed de novo production. Thus, modeling of monoterpenoid emissions required a hybrid model in which a significant fraction of emissions was dependent on both light and temperature, while the remainder was dependent on temperature alone. Experiments in which stomata were forced to close using abscisic acid demonstrated that MBO and a large fraction of the monoterpene flux, presumably linalool, could be limited at the scale of seconds to minutes by stomatal conductance. Using a previously published model of terpenoid emissions which explicitly accounts for the physico-chemical properties of emitted compounds, we are able to simulate these observed stomatal effects, whether induced through experimentation or arising under naturally fluctuation conditions of temperature and light. This study shows unequivocally that, under naturally occurring field conditions, de novo light dependent monoterpenes can comprise a large fraction of emissions. Differences between the monoterpene composition of ambient air and needle emissions imply a significant non-needle emission source enriched in Δ-3-carene.

  9. Near-infrared diode-pumped white-light emission from erbium-doped calcium fluoride crystal

    Science.gov (United States)

    Culp, Mical; Edwards, Vernessa M.; Reddi, B. Rami

    2016-02-01

    CaF2 is a cubic material and Erbium enters the lattice in triply ionized state. Erbium occupies Ca sites in the material. Defects occur in the material because a trivalent dopant ion replaces a divalent host ion. Er3+ occupies several different sites. Absorption spectrum of Er3+-doped CaF2 revealed absorption peaks at 255, 365, 379, 407, 441, 449, 487, 522, 539, 652 and 798 nm. When the sample was excited with an 800 nm near-infrared laser it revealed emissions at 390, 415, 462, 555, 665 and 790 nm. The absorption and emission peaks are identified with Er3+ spectral transitions. The sample color appears to be either white or green under near-infrared laser excitation. Emission color was found to be dependent on the pump laser wavelength used and laser power. Excitation spectral recordings were made by tuning the pump laser wavelength. The sample emission appears to be white under near-infrared excitation as well as violet laser excitation. Excited state lifetimes are measured to analyze the data. Our studies indicate that this sample is useful in solid state lighting applications.

  10. Light

    CERN Document Server

    Rivera, Andrea

    2017-01-01

    Light is all around us. Learn how it is used in art, technology, and engineering. Five easy-to-read chapters explain the science behind light, as well as its real-world applications. Vibrant, full-color photos, bolded glossary words, and a key stats section let readers zoom in even deeper. Aligned to Common Core Standards and correlated to state standards. Abdo Zoom is a division of ABDO.

  11. Stable angular emission spectra in white organic light-emitting diodes using graphene/PEDOT:PSS composite electrode.

    Science.gov (United States)

    Cho, Hyunsu; Lee, Hyunkoo; Lee, Jonghee; Sung, Woo Jin; Kwon, Byoung-Hwa; Joo, Chul-Woong; Shin, Jin-Wook; Han, Jun-Han; Moon, Jaehyun; Lee, Jeong-Ik; Cho, Seungmin; Cho, Nam Sung

    2017-05-01

    In this work, we suggest a graphene/ poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) composite as a transparent electrode for stabilizing white emission of organic light-emitting diodes (OLEDs). Graphene/PEDOT:PSS composite electrodes have increased reflectance when compared to graphene itself, but their reflectance is still lower than that of ITO itself. Changes in the reflectance of the composite electrode have the advantage of suppressing the angular spectral distortion of white emission OLEDs and achieving an efficiency of 16.6% for white OLEDs, comparable to that achieved by graphene-only electrodes. By controlling the OLED structure to compensate for the two-beam interference effect, the CIE color coordinate change (Δxy) of OLEDs based on graphene/PEDOT:PSS composite electrodes is 0.018, less than that based on graphene-only electrode, i.e.,0.027.

  12. Impact of electric fields on the emission from organic light-emitting diodes based on polyvinylcarbazole (PVK)

    Energy Technology Data Exchange (ETDEWEB)

    Yang Shengyi [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China)]. E-mail: syyang@center.njtu.edu.cn; Liu Deang [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China); Jiang Yan [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China); Teng Feng [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China); Xu Zheng [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China); Hou Yanbing [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China); Xu Xurong [Key Laboratory of Luminescence and Optical Information, Ministry of Education, Institute of Optoelectronic Technology, Beijing Jiatong University, Beijing 100044 (China)

    2007-01-15

    Influences of electric fields on the emission from organic light-emitting diodes (OLEDs) based on 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP) and polyvinylcarbazole (PVK) are studied. Electroluminescence (EL) spectra are very different from its photoluminescence (PL) for blend of PVK and BCP in the weight ratio M {sub PVK}:M {sub BCP}=1:3. EL spectrum of device ITO/Blend/BCP(20 nm)/Alq{sub 3}(12 nm)/Al maximizes at 500 nm. For trilayer device ITO/PVK/BCP(10 nm)/Alq{sub 3}(10 nm)/Al, the relative emission intensity of PVK to BCP, initially increases and then decreases with increasing electric field. Under high electric fields, holes can transport through thinner BCP layer and recombine with electrons in Alq {sub 3} layer.

  13. Fracto-mechanoluminescent light emission of EuD4TEA-PDMS composites subjected to high strain-rate compressive loading

    Science.gov (United States)

    Ryu, Donghyeon; Castaño, Nicolas; Bhakta, Raj; Kimberley, Jamie

    2017-08-01

    The objective of this study is to understand light emission characteristics of fracto-mechanoluminescent (FML) europium tetrakis(dibenzoylmethide)-triethylammonium (EuD4TEA) crystals under high strain-rate compressive loading. As a sensing material that can play a pivotal role for the self-powered impact sensor technology, it is important to understand transformative light emission characteristics of the FML EuD4TEA crystals under high strain-rate compressive loading. First, EuD4TEA crystals were synthesized and embedded into polydimethylsiloxane (PDMS) elastomer to fabricate EuD4TEA-PDMS composite test specimens. Second, the prepared EuD4TEA-PDMS composites were tested using the modified Kolsky bar setup equipped with a high-speed camera. Third, FML light emission was captured to yield 12 bit grayscale video footage, which was processed to quantify the FML light emission. Finally, quantitative parameters were generated by taking into account pixel values and population of pixels of the 12 bit grayscale images to represent FML light intensity. The FML light intensity was correlated with high strain-rate compressive strain and strain rate to understand the FML light emission characteristics under high strain-rate compressive loading that can result from impact occurrences.

  14. Measurement of the radial density distribution of the light emissions near the trajectory of fast ions in nitrogen

    International Nuclear Information System (INIS)

    Ibach, T.

    1983-11-01

    For the analysis of the emission and deceleration mechanisms of ionisation-electrons (delta-electrons) during the passage of fast ions through gases, the radial density distribution of the light emission has been measured, which is related with the (0,0)-transitions of two optical bands in nitrogen. These measurements have been made using a small aperture limited ion beam. The first band under study is the 2. positive system at 337.1 nm excited mainly by low energy electrons around 20 eV, and the second band is the 1. negative system at 391.4 nm excited by fast electrons with simultaneous ionisation. For these measurements an experimental setup has been developed with a telescope-like optical system and interference filters to detect the emitted light with a high spacial resolution (4x10 -4 of profile width) and a high dynamic range (10 6 ). The experiments have been performed using proton beams of different energies between 270 keV and 2.8 MeV, He-3 beams with 270 keV/u and 500 keV/u and a Ne beam with 270 keV/u with gas pressures in the range between 0.133 to 13.3 mbar. Based on the method of Abel inversion the spacial light emission density is deduced from the experimental distance functions and normalized to a gas density of 1 g/cm 3 . The results show that approximately half of the total light emission in the 1. negative system and the ionisation is caused by the primary interaction of the ion beam. For the same energy per nucleon this contribution decreases relative to the contribution of the delta-electrons with increasing atomic number. In addition the delta-radiation becomes harder with increasing atomic number. Good agreement is obtained by comparison with the results of other authors, which are based on probe techniques and Monte-Carlo-calculations. (orig./HP) [de

  15. Efficient white phosphorescent organic light-emitting diodes consisting of orange ultrathin and blue mixed host emission layers

    Science.gov (United States)

    Sheng, Ren; Zuo, Liangmei; Xue, Kaiwen; Duan, Yu; Chen, Ping; Cheng, Gang; Zhao, Yi

    2016-08-01

    We have successfully demonstrated highly efficient white phosphorescent organic light-emitting diodes (OLEDs) by inserting an ultrathin non-doped orange layer within blue mixed host emission layer. The key feature of the novel device is the employment of blue mixed host and orange ultrathin layers, resulting in an extended recombination region and more balanced charge carrier. The maximum efficiencies of 33.8 lm W-1 and 32.2 cd A-1 are obtained. Moreover, the resulting white device achieves a slight efficiency roll-off and a high luminance at low operating voltage. Our versatile concept suggests a promising simple method to achieve high performance white OLEDs.

  16. Cost-Benefit Analysis and Emission Reduction of Energy Efficient Lighting at the Universiti Tenaga Nasional

    Directory of Open Access Journals (Sweden)

    G. S. B. Ganandran

    2014-01-01

    Full Text Available This paper reports the result of an investigation on the potential energy saving of the lighting systems at selected buildings of the Universiti Tenaga Nasional. The scope of this project includes evaluation of the lighting system in the Library, Admin Building, College of Engineering, College of Information Technology, Apartments, and COE Food court of the university. The main objectives of this project are to design the proper retrofit scenario and to calculate the potential electricity saving, the payback period, and the potential environmental benefits. In this survey the policy for retrofitting the old lighting system with the new energy saving LEDs starts with 10% for the first year and continues constantly for 10 years until all the lighting systems have been replaced. The result of the life cycle analysis reveals that after four years, the selected buildings will bring profit for the investment.

  17. Cost-Benefit Analysis and Emission Reduction of Energy Efficient Lighting at the Universiti Tenaga Nasional

    Science.gov (United States)

    Ganandran, G. S. B.; Mahlia, T. M. I.; Ong, Hwai Chyuan; Rismanchi, B.; Chong, W. T.

    2014-01-01

    This paper reports the result of an investigation on the potential energy saving of the lighting systems at selected buildings of the Universiti Tenaga Nasional. The scope of this project includes evaluation of the lighting system in the Library, Admin Building, College of Engineering, College of Information Technology, Apartments, and COE Food court of the university. The main objectives of this project are to design the proper retrofit scenario and to calculate the potential electricity saving, the payback period, and the potential environmental benefits. In this survey the policy for retrofitting the old lighting system with the new energy saving LEDs starts with 10% for the first year and continues constantly for 10 years until all the lighting systems have been replaced. The result of the life cycle analysis reveals that after four years, the selected buildings will bring profit for the investment. PMID:25133258

  18. Cost-benefit analysis and emission reduction of energy efficient lighting at the Universiti Tenaga Nasional.

    Science.gov (United States)

    Ganandran, G S B; Mahlia, T M I; Ong, Hwai Chyuan; Rismanchi, B; Chong, W T

    2014-01-01

    This paper reports the result of an investigation on the potential energy saving of the lighting systems at selected buildings of the Universiti Tenaga Nasional. The scope of this project includes evaluation of the lighting system in the Library, Admin Building, College of Engineering, College of Information Technology, Apartments, and COE Food court of the university. The main objectives of this project are to design the proper retrofit scenario and to calculate the potential electricity saving, the payback period, and the potential environmental benefits. In this survey the policy for retrofitting the old lighting system with the new energy saving LEDs starts with 10% for the first year and continues constantly for 10 years until all the lighting systems have been replaced. The result of the life cycle analysis reveals that after four years, the selected buildings will bring profit for the investment.

  19. N2O emission from plant surfaces – light stimulated and a global phenomenon

    DEFF Research Database (Denmark)

    Mikkelsen, Teis Nørgaard; Bruhn, Dan; Ambus, Per

    2017-01-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone depletingmono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertaintiesare associated with the distinct source strengths. Here we investigate...... for the first time N2O emission fromterrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurementsto investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and withoutUV-screening. Further laboratory tests were conducted...... with a range of species to study the controls and possibleloci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c.20-50 nmol m-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a ratherhigh activation energy indicative...

  20. Barium light source method and apparatus

    Science.gov (United States)

    Curry, John J. (Inventor); MacDonagh-Dumler, Jeffrey (Inventor); Anderson, Heidi M. (Inventor); Lawler, James E. (Inventor)

    2002-01-01

    Visible light emission is obtained from a plasma containing elemental barium including neutral barium atoms and barium ion species. Neutral barium provides a strong green light emission in the center of the visible spectrum with a highly efficient conversion of electrical energy into visible light. By the selective excitation of barium ionic species, emission of visible light at longer and shorter wavelengths can be obtained simultaneously with the green emission from neutral barium, effectively providing light that is visually perceived as white. A discharge vessel contains the elemental barium and a buffer gas fill therein, and a discharge inducer is utilized to induce a desired discharge temperature and barium vapor pressure therein to produce from the barium vapor a visible light emission. The discharge can be induced utilizing a glow discharge between electrodes in the discharge vessel as well as by inductively or capacitively coupling RF energy into the plasma within the discharge vessel.

  1. Red light emission from ZnO:Eu{sup 3+}|CuSCN hetero-junction under cathodic polarization

    Energy Technology Data Exchange (ETDEWEB)

    Sirimanne, P.M., E-mail: psirimane@hotmail.com [Department of Science and Technology, Uwa Wellassa University, Badulla (Sri Lanka); Minoura, H. [Environmental and Renewable Energy Systems Division, Graduate School of Engineering, Gifu University, 1-1 Yanagido, Gifu 501-1193 (Japan)

    2015-09-15

    Eu{sup 3+} ions were bonded to ZnO ceramic via organic ligand. Surface bonded Eu{sup 3+} ions were exhibited specific luminescence bands due to electron transitions between f–f intra-configurationally transitions. Further enhancement of luminescence bands was observed by attaching selected oligomers to Eu{sup 3+} ions. A hetero-junction was prepared by depositing copper-thiocyanate on Eu{sup 3+} ions bonded ZnO ceramic. Red light emission was observed from surface bonded Eu{sup 3+} ions in ZnO:Eu{sup 3+}|CuSCN hetero-junction under reverse bias. - Highlights: • Europium doped ZnO ceramic exhibits photo-luminescence. • Semiconductor hetro-junction was prepared. • ZnO:Eu{sup 3+}|CuSCN hetero-junction emits red light under reverse bias.

  2. Influence of microwave plasma parameters on light emission from SiV color centers in nanocrystalline diamond films

    Directory of Open Access Journals (Sweden)

    Himics László

    2014-11-01

    Full Text Available Zero phonon line (ZPL shape, position and integral intensity of SiV defect center in diamond is presented for nanocrystalline diamond (NCD films grown at different conditions, NCD films of average grain sizes from ~50 nm up to ~180 nm have been deposited onto c-Si wafer at substrate temperature of 700 and 850oC from mixture with different CH4 and H2 ratios using MWCVD process. Light emission of SiV defect center and Raman scattering properties of NCD samples were measured on a Renishaw micro-Raman spectrometer with 488 nm excitation. Scanning electron microscopy images were used for monitoring surface morphology and for the analysis of the average grain sizes. Sample thickness was determined by in situ laser reflection interferometry. Characteristics of SiV ZPL are discussed in light of the morphology, bonding structure and average grain size of NCD films.

  3. Defect induced visible-light-activated near-infrared emissions in Gd3-x-y-zYbxBiyErzGa5O12

    Science.gov (United States)

    Tong, Liping; Saito, Katsuhiko; Guo, Qixin; Zhou, Han; Fan, Tongxiang; Zhang, Di

    2017-11-01

    Visible-light-activated near-infrared luminescent materials are promising photoluminescent materials due to their convenience and low cost. Crystal defects can seriously affect the performance of luminescent materials, and better understanding of the complexity of the structural disorder and electronic structures of such materials opens up new possibilities in luminescent material development. In this work, we successfully design a novel, effective, visible-light-activated near-infrared luminescent Gd3Ga5O12: 4.2%Yb3+, 8.4%Er3+, and 4.2%Bi3+ system based on first principles. This exhibits strong emission intensity and high luminous efficiency (0.993) and also has a lifetime (7.002 ms) that is at least twice as long as the longest lifetime reported in published papers. We utilize density functional theory with an effective LSDA + U method to study the structural properties of Gd3-x-y-zGa5O12: xYb3+, yBi3+, zEr3+ (GGG: Yb3+, Bi3+, Er3+). The d and f electron orbits of rare-earth ions are considered for an effective Hund exchange. Detailed analysis reveals that GGG: 4.2%Yb3+, 8.4%Er3+, 4.2%Bi3+ has the smallest cell volume because of the strong covalent bonds of Bi-O, Er-O, and Yb-O. Bi 3d is a hybridized state that acts as sensitizing ions during the process of luminescence in GGG: Yb3+, Bi3+, Er3+. Together with experimental and theoretical results, we analyze the influence of defects on emission intensity. The locations of Yb3+, Er3+, and Bi3+ are determined by X-ray absorption fine structure measurements, which are in agreement with the model constructed using first principles. This work may provide innovative guidance for the design of high-performance visible-light-activated near-infrared luminophores based on calculations and a new methodology for application of coherent laser radar and optical communication.

  4. Modeling transitions in the California light-duty vehicles sector to achieve deep reductions in transportation greenhouse gas emissions

    International Nuclear Information System (INIS)

    Leighty, Wayne; Ogden, Joan M.; Yang, Christopher

    2012-01-01

    California’s target for reducing economy-wide greenhouse gas (GHG) emissions is 80% below 1990 levels by 2050. We develop transition scenarios for meeting this goal in California’s transportation sector, with focus on light-duty vehicles (LDVs). We explore four questions: (1) what options are available to reduce transportation sector GHG emissions 80% below 1990 levels by 2050; (2) how rapidly would transitions in LDV markets, fuels, and travel behaviors need to occur over the next 40 years; (3) how do intermediate policy goals relate to different transition pathways; (4) how would rates of technological change and market adoption between 2010 and 2050 impact cumulative GHG emissions? We develop four LDV transition scenarios to meet the 80in50 target through a combination of travel demand reduction, fuel economy improvements, and low-carbon fuel supply, subject to restrictions on trajectories of technological change, potential market adoption of new vehicles and fuels, and resource availability. These scenarios exhibit several common themes: electrification of LDVs, rapid improvements in vehicle efficiency, and future fuels with less than half the carbon intensity of current gasoline and diesel. Availability of low-carbon biofuels and the level of travel demand reduction are “swing factors” that influence the degree of LDV electrification required. - Highlights: ► We model change in California LDVs for deep reduction in transportation GHG emissions. ► Reduced travel demand, improved fuel economy, and low-carbon fuels are all needed. ► Transitions must begin soon and occur quickly in order to achieve the 80in50 goal. ► Low-C biofuel supply and travel demand influence the need for rapid LDV electrification. ► Cumulative GHG emissions from LDVs can differ between strategies by up to 40%.

  5. [PS II photochemical efficiency in flag leaf of wheat varieties and its adaptation to strong sun- light intensity on farmland of Xiangride in Qinghai Province, Northwest China].

    Science.gov (United States)

    Shi, Sheng-Bo; Chen, Wen-Jie; Shi, Rui; Li, Miao; Zhang, Huai-Gang; Sun, Ya-Nan

    2014-09-01

    Taking four wheat varieties developed by Northwest Institute of Plateau Biology, Chinese Academy of Sciences, as test materials, with the measurement of content of photosynthetic pigments, leaf area, fresh and dry mass of flag leaf, the PS II photochemistry efficiency of abaxial and adaxial surface of flag leaf and its adaptation to strong solar radiation during the period of heading stage in Xiangride region were investigated with the pulse-modulated in-vivo chlorophyll fluorescence technique. The results indicated that flag leaf angle mainly grew in horizontal state in Gaoyuan 314, Gaoyuan 363 and Gaoyuan 584, and mainly in vertical state in Gaoyuan 913 because of its smaller leaf area and larger width. Photosynthetic pigments were different among the 4 varieties, and positively correlated with intrinsic PS II photochemistry efficiencies (Fv/Fm). In clear days, especially at noon, the photosynthetic photoinhibition was more serious in abaxial surface of flag leaf due to directly facing the solar radiation, but it could recover after reduction of sunlight intensity in the afternoon, which meant that no inactive damage happened in PS II reaction centers. There were significant differences of PS II actual and maximum photochemical efficiencies at the actinic light intensity (ΦPS II and Fv'/Fm') between abaxial and adaxial surface, and their relative variation trends were on the contrary. The photochemical and non-photochemical quenching coefficients (qP and NPQ) had a similar tendency in both abaxial and adaxial surfaces. Although ΦPS II and qP were lower in adaxial surface of flag leaf, the Fv'/Fm' was significantly higher, which indicated that the potential PS II capture efficiency of excited energy was higher. The results demonstrated that process of photochemical and non-photochemical quenching could effectively dissipate excited energy caused by strong solar radiation, and there were higher adaptation capacities in wheat varieties natively cultivated in

  6. Results on Λp emission from K− absorption at rest on light nuclei

    International Nuclear Information System (INIS)

    Agnello, M.; Benussi, L.; Bertani, M.; Bhang, H.C.; Bonomi, G.; Botta, E.; Bregant, M.; Bressani, T.; Bufalino, S.; Busso, L.; Calvo, D.; Camerini, P.; Dalena, B.; De Mori, F.; D'Erasmo, G.; Fabbri, F.L.

    2013-01-01

    The analysis of the first FINUDA paper on the emission of Λp pairs following the K − absorption at rest on 6 Li, 7 Li, 12 C nuclei has been revised by using a much larger data set and an updated analysis techniques. The preliminary results regarding the 9 Be(K stop − ,Λp)X reaction are discussed

  7. Light

    CERN Document Server

    Ditchburn, R W

    1963-01-01

    This classic study, available for the first time in paperback, clearly demonstrates how quantum theory is a natural development of wave theory, and how these two theories, once thought to be irreconcilable, together comprise a single valid theory of light. Aimed at students with an intermediate-level knowledge of physics, the book first offers a historical introduction to the subject, then covers topics such as wave theory, interference, diffraction, Huygens' Principle, Fermat's Principle, and the accuracy of optical measurements. Additional topics include the velocity of light, relativistic o

  8. Dominant transverse-electric polarized emission from 298 nm MBE-grown AlN-delta-GaN quantum well ultraviolet light-emitting diodes

    Science.gov (United States)

    Liu, Cheng; Ooi, Yu Kee; Islam, S. M.; Xing, Huili Grace; Jena, Debdeep; Zhang, Jing

    2017-02-01

    III-nitride based ultraviolet (UV) light emitting diodes (LEDs) are of considerable interest in replacing gas lasers and mercury lamps for numerous applications. Specifically, AlGaN quantum well (QW) based LEDs have been developed extensively but the external quantum efficiencies of which remain less than 10% for wavelengths <300 nm due to high dislocation density, difficult p-type doping and most importantly, the physics and band structure from the three degeneration valence subbands. One solution to address this issue at deep UV wavelengths is by the use of the AlGaN-delta-GaN QW where the insertion of the delta-GaN layer can ensure the dominant conduction band (C) - heavyhole (HH) transition, leading to large transverse-electric (TE) optical output. Here, we proposed and investigated the physics and polarization-dependent optical characterizations of AlN-delta- GaN QW UV LED at 300 nm. The LED structure is grown by Molecular Beam Epitaxy (MBE) where the delta-GaN layer is 3-4 monolayer (QW-like) sandwiched by 2.5-nm AlN sub-QW layers. The physics analysis shows that the use of AlN-delta-GaN QW ensures a larger separation between the top HH subband and lower-energy bands, and strongly localizes the electron and HH wave functions toward the QW center and hence resulting in 30-time enhancement in TEpolarized spontaneous emission rate, compared to that of a conventional Al0.35Ga0.65N QW. The polarization-dependent electroluminescence measurements confirm our theoretical analysis; a dominant TE-polarized emission was obtained at 298 nm with a minimum transverse-magnetic (TM) polarized emission, indicating the feasibility of high-efficiency TEpolarized UV emitters based on our proposed QW structure.

  9. N2O emission from plant surfaces - light stimulated and a global phenomenon.

    Science.gov (United States)

    Mikkelsen, Teis; Bruhn, Dan; Ambus, Per

    2017-04-01

    Nitrous oxide (N2O) is an important long-lived greenhouse gas and precursor of stratospheric ozone depleting mono-nitrogen oxides. The atmospheric concentration of N2O is persistently increasing; however, large uncertainties are associated with the distinct source strengths. Here we investigate for the first time N2O emission from terrestrial vegetation in response to natural solar ultra violet radiation. We conducted field site measurements to investigate N2O atmosphere exchange from grass vegetation exposed to solar irradiance with and without UV-screening. Further laboratory tests were conducted with a range of species to study the controls and possible loci of UV-induced N2O emission from plants. Plants released N2O in response to natural sunlight at rates of c. 20-50 nmol m-2 h-1, mostly due to the UV component. The emission rate is temperature dependent with a rather high activation energy indicative for an abiotic process. The prevailing zone for the N2O formation appears to be at the very surface of leaves. However, only c. 26% of the UV-induced N2O appears to originate from plant-N. Further, the process is dependent on atmospheric oxygen concentration. Our work demonstrates that ecosystem emission of the important greenhouse gas, N2O, may be up to c. 30% higher than hitherto assumed. Literature: Mikkelsen TN, Bruhn D & Ambus P. (2016). Solar UV Irradiation-Induced Production of Greenhouse Gases from Plant Surfaces: From Leaf to Earth. Progress in Botany, DOI 10.1007/124_2016_10. Bruhn D, Albert KR, Mikkelsen TN & Ambus P. (2014). UV-induced N2O emission from plants. Atmospheric Environment 99, 206-214.

  10. UV-A emission from fluorescent energy-saving light bulbs alters local retinoic acid homeostasis.

    Science.gov (United States)

    Hellmann-Regen, Julian; Heuser, Isabella; Regen, Francesca

    2013-12-01

    Worldwide bans on incandescent light bulbs (ILBs) drive the use of compact fluorescent light (CFL) bulbs, which emit ultraviolet (UV) radiation. Potential health issues of these light sources have already been discussed, including speculation about the putative biological effects on light exposed tissues, yet the underlying mechanisms remain unclear. We hypothesized photoisomerization of all-trans retinoic acid (at-RA), a highly light sensitive morphogen, into biologically less active isomers, as a mechanism mediating biological effects of CFLs. Local at-RA is anti-carcinogenic, entrains molecular rhythms and is crucial for skin homeostasis. Therefore, we quantified the impact of CFL irradiation on extra- and intracellular levels of RA isomers using an epidermal cell culture model. Moreover, a biologically relevant impact of CFL irradiation was assessed using highly at-RA-sensitive human neuroblastoma cells. Dose-dependent conversion of extra- and intracellular at-RA into the biologically less active 13-cis-isomer was significantly higher in CFL vs. ILB exposure and completely preventable by employing a UV-filter. Moreover, pre-irradiation of culture media by CFL attenuated at-RA-specific effects on cell viability in human at-RA-sensitive cells in a dose-dependent manner. These findings point towards a biological relevance of CFL-induced at-RA decomposition, providing a mechanism for CFL-mediated effects on environmental health.

  11. Reduce growth rate of light-duty vehicle travel to meet 2050 global climate goals

    Energy Technology Data Exchange (ETDEWEB)

    Sager, Jalel; Apte, Joshua S; Lemoine, Derek M; Kammen, Daniel M, E-mail: jalel.sager@berkeley.edu, E-mail: japte@berkeley.edu, E-mail: dlemoine@berkeley.edu, E-mail: daniel.kammen@gmail.com [Energy and Resources Group, University of California, Berkeley, CA (United States)

    2011-04-15

    Strong policies to constrain increasing global use of light-duty vehicles (cars and light trucks) should complement fuel efficiency and carbon intensity improvements in order to meet international greenhouse gas emission and climate targets for the year 2050.

  12. Emission and absorption of light in poly pyrrole synthesized by plasma

    International Nuclear Information System (INIS)

    Enriquez, M.A.; Colin, E.; Olayo, M.G.; Cruz, G.J.; Ordonez, E.; Benavides, R.; Morales, J.; Olayo, R.

    2007-01-01

    The poly pyrrole structure (PPy) consists of heterocyclic rings with conjugation that it depends on the intensity of the electric field applied during the synthesis, and its luminescence is related with the π-π * transitions of that conjugation. To irradiate with light of different wavelengths, the results indicate that the polymer absorbs in the interval from 290 to 700 nm and it emits between 450 and 470 nm. The basal conductivity of the polymers, without electromagnetic excitation, it was measured in 10 -15 S/cm, however, to interact with visible light it is increased approximately 10 times and when excite with UV light it is increased up to 3 magnitude orders. (Author)

  13. The recession of 2008 and its impact on light-duty vehicle emissions in three western United States cities.

    Science.gov (United States)

    Bishop, Gary A; Stedman, Donald H

    2014-12-16

    The global economic recession of 2008-2010 severely depressed light-duty vehicle sales in the United States. On-road fleets observed with a remote vehicle exhaust sensor in 2013 at three historical sampling locations in Denver, Los Angeles, and Tulsa showed large reductions in the fleet fractions of 2009 model year vehicles of 40%, 38%, and 35%, respectively, when compared to prerecession 2007 levels with the light-duty truck category suffering the largest percentage declines. The fleet fraction for these ∼ 5 year old vehicles is normally reserved for vehicles more than twice their age. This resulted in a significant increase in the on-road freeway fleet age, which had been relatively stable. The fleet average age increased by two years in Denver and Los Angeles but only by one year in Tulsa, likely due to its faster economic recovery. Using fleet fractions from previous data sets, we estimated age-adjusted mean emissions increases for the 2013 fleet to be 17-29% higher for carbon monoxide, 9-14% higher for hydrocarbons, 27-30% higher for nitric oxide, and 7-16% higher for ammonia emissions than if historical fleet turnover rates had prevailed.

  14. Experimental and Numerical Evaluation of the Mechanical Behavior of Strongly Anisotropic Light-Weight Metallic Fiber Structures under Static and Dynamic Compressive Loading

    Directory of Open Access Journals (Sweden)

    Olaf Andersen

    2016-05-01

    Full Text Available Rigid metallic fiber structures made from a variety of different metals and alloys have been investigated mainly with regard to their functional properties such as heat transfer, pressure drop, or filtration characteristics. With the recent advent of aluminum and magnesium-based fiber structures, the application of such structures in light-weight crash absorbers has become conceivable. The present paper therefore elucidates the mechanical behavior of rigid sintered fiber structures under quasi-static and dynamic loading. Special attention is paid to the strongly anisotropic properties observed for different directions of loading in relation to the main fiber orientation. Basically, the structures show an orthotropic behavior; however, a finite thickness of the fiber slabs results in moderate deviations from a purely orthotropic behavior. The morphology of the tested specimens is examined by computed tomography, and experimental results for different directions of loading as well as different relative densities are presented. Numerical calculations were carried out using real structural data derived from the computed tomography data. Depending on the direction of loading, the fiber structures show a distinctively different deformation behavior both experimentally and numerically. Based on these results, the prevalent modes of deformation are discussed and a first comparison with an established polymer foam and an assessment of the applicability of aluminum fiber structures in crash protection devices is attempted.

  15. Highly polarized light emission by isotropic quantum dots integrated with magnetically aligned segmented nanowires

    International Nuclear Information System (INIS)

    Uran, Can; Erdem, Talha; Guzelturk, Burak; Perkgöz, Nihan Kosku; Jun, Shinae; Jang, Eunjoo; Demir, Hilmi Volkan

    2014-01-01

    In this work, we demonstrate a proof-of-concept system for generating highly polarized light from colloidal quantum dots (QDs) coupled with magnetically aligned segmented Au/Ni/Au nanowires (NWs). Optical characterizations reveal that the optimized QD-NW coupled structures emit highly polarized light with an s-to p-polarization (s/p) contrast as high as 15:1 corresponding to a degree of polarization of 0.88. These experimental results are supported by the finite-difference time-domain simulations, which demonstrate the interplay between the inter-NW distance and the degree of polarization.

  16. InGaAs quantum dots grown by molecular beam epitaxy for light emission on Si substrates.

    Science.gov (United States)

    Bru-Chevallier, C; El Akra, A; Pelloux-Gervais, D; Dumont, H; Canut, B; Chauvin, N; Regreny, P; Gendry, M; Patriarche, G; Jancu, J M; Even, J; Noe, P; Calvo, V; Salem, B

    2011-10-01

    The aim of this study is to achieve homogeneous, high density and dislocation free InGaAs quantum dots grown by molecular beam epitaxy for light emission on silicon substrates. This work is part of a project which aims at overcoming the severe limitation suffered by silicon regarding its optoelectronic applications, especially efficient light emission device. For this study, one of the key points is to overcome the expected type II InGaAs/Si interface by inserting the InGaAs quantum dots inside a thin silicon quantum well in SiO2 fabricated on a SOI substrate. Confinement effects of the Si/SiO2 quantum well are expected to heighten the indirect silicon bandgap and then give rise to a type I interface with the InGaAs quantum dots. Band structure and optical properties are modeled within the tight binding approximation: direct energy bandgap is demonstrated in SiO2/Si/InAs/Si/SiO2 heterostructures for very thin Si layers and absorption coefficient is calculated. Thinned SOI substrates are successfully prepared using successive etching process resulting in a 2 nm-thick Si layer on top of silica. Another key point to get light emission from InGaAs quantum dots is to avoid any dislocations or defects in the quantum dots. We investigate the quantum dot size distribution, density and structural quality at different V/III beam equivalent pressure ratios, different growth temperatures and as a function of the amount of deposited material. This study was performed for InGaAs quantum dots grown on Si(001) substrates. The capping of InGaAs quantum dots by a silicon epilayer is performed in order to get efficient photoluminescence emission from quantum dots. Scanning transmission electronic microscopy images are used to study the structural quality of the quantum dots. Dislocation free In50Ga50As QDs are successfully obtained on a (001) silicon substrate. The analysis of QDs capped with silicon by Rutherford Backscattering Spectrometry in a channeling geometry is also presented.

  17. Fabrication of ZnO Thin Films by Sol-Gel Spin Coating and Their UV and White-Light Emission Properties

    Science.gov (United States)

    Kumar, Mirgender; Dubey, Sarvesh; Rajendar, Vanga; Park, Si-Hyun

    2017-10-01

    ZnO thin films have been fabricated by the sol-gel spin-coating technique and annealed under different conditions, and their ultraviolet (UV) and white-light emission properties investigated. Different ambient conditions including oxygen, nitrogen, zinc-rich nitrogen, and vacuum were used to tune the main properties of the ZnO thin films. The resistivity varied from the conductive to semi-insulating regime, and the luminescence emission from fairly intense UV to polychromatic. The emission intensity was also found to be a function of the annealing conditions. Possible routes to compensate the loss of emission characteristics are discussed. X-ray photoelectron spectroscopy (XPS) analysis was carried out to detect the chemical states of the zinc/oxygen species. The changes in the electrical and emission properties are explained based on annihilation/formation of inherent donor/acceptor-type defects. Such ZnO thin films could have potential applications in solid-state lighting.

  18. Study of Sequential Dexter Energy Transfer in High Efficient Phosphorescent White Organic Light-Emitting Diodes with Single Emissive Layer

    Science.gov (United States)

    Kim, Jin Wook; You, Seung Il; Kim, Nam Ho; Yoon, Ju-An; Cheah, Kok Wai; Zhu, Fu Rong; Kim, Woo Young

    2014-01-01

    In this study, we report our effort to realize high performance single emissive layer three color white phosphorescent organic light emitting diodes (PHOLEDs) through sequential Dexter energy transfer of blue, green and red dopants. The PHOLEDs had a structure of; ITO(1500 Å)/NPB(700 Å)/mCP:Firpic-x%:Ir(ppy)3-0.5%:Ir(piq)3-y%(300 Å)/TPBi(300 Å)/Liq(20 Å)/Al(1200 Å). The dopant concentrations of FIrpic, Ir(ppy)3 and Ir(piq)3 were adjusted and optimized to facilitate the preferred energy transfer processes attaining both the best luminous efficiency and CIE color coordinates. The presence of a deep trapping center for charge carriers in the emissive layer was confirmed by the observed red shift in electroluminescent spectra. White PHOLEDs, with phosphorescent dopant concentrations of FIrpic-8.0%:Ir(ppy)3-0.5%:Ir(piq)3-0.5% in the mCP host of the single emissive layer, had a maximum luminescence of 37,810 cd/m2 at 11 V and a luminous efficiency of 48.10 cd/A at 5 V with CIE color coordinates of (0.35, 0.41). PMID:25388087

  19. Light particle emission measurements in heavy ion reactions: Progress report, June 1, 1986-May 31, 1987

    International Nuclear Information System (INIS)

    Petitt, G.A.

    1987-01-01

    During the past year we have completed our work on neutron emission in coincidence with fission fragments from the 158 Er system. In addition to this we have completed preliminary analysis of our results on neutron emission from products of damped reactions between 58 Ni and 165 Ho at 930 MeV. Two experiments were planned for the present contract period as discussed in our proposal for 1986-87. One of these, to measure the mass and charge distributions from projectile-like fragments (PLF) in the reactions 58 Ni + 165 Ho and 58 Ni + 58 Ni using the time-of-flight facility at the HHIRF has been successfully completed. The other, to measure momentum correlations between neutrons and charged particles produced in central collisions between 32 S + 197 Au is scheduled to be run in mid-February. 14 refs., 4 figs

  20. Emission Gas Reducer on Motor Vehicle, Automobile, Light Engine of Boat and Stationary Combustion Engine.

    Directory of Open Access Journals (Sweden)

    I Gusti Bagus Wijaya Kusuma

    2010-10-01

    Full Text Available The use of motor vehicle should be followed by protection against damages on the environment, since the exhaust gas from combustion engine has significantly affect on air and environmental pollution. One method to solve the problems in air pollution has been done by using a re-heater designed in Mechanical Engineering Department, University of Udayana. In accordance to the test on the re-heater, it can be seen very clear that the re-heater has significantly reduce the CO emission of about 54%. It also reduces the CO2 dan HC emission, and in the other side increases the number of O2. The re-heater has no significant effect to engine performance during the operation and also reduces the noise of motor.

  1. Fragment emission studies in low energy light heavy-ion reactions

    Directory of Open Access Journals (Sweden)

    Rana T. K.

    2015-01-01

    Full Text Available Fragment emission mechanisms have been studied in 12C on 12C and 13C on 12C reactions at same excitation energy. The inclusive energy distributions of the complex fragments (3≤ Z ≤ 5 emitted from the composite system have been measured in the angular range 14° to 36°. The present experiments have been performed with the motivation to study the isotopic dependence of fragment yields in these two reactions. From the preliminary analysis, it has been observed that fragments are emitted from a completely equilibrated and long lived composite system for both 12C + 12C and 13C + 12C reactions. It has also been observed that the emission of neutron-rich fragments are more in 13C + 12C compared to 12C + 12C reaction.

  2. Emissions of CO2, CO, NOx, HC, PM, HFC-134a, N2O and CH4 from the global light duty vehicle fleet

    Directory of Open Access Journals (Sweden)

    Timothy J. Wallington

    2008-04-01

    Full Text Available Vehicles emit carbon dioxide (CO2, carbon monoxide (CO, nitrogen oxides (NOx, hydrocarbons (HC, particulate matter (PM, hydrofluorocarbon 134a (HFC-134a, methane (CH4, and nitrous oxide (N2O. An understanding of these emissions is needed in discussions of climate change and local air pollution issues. To facilitate such discussions an overview of past, present, and likely future emissions from light duty vehicles is presented. Emission control technologies have reduced the emissions of CO, VOCs, PM, HFC-134a, CH4, and N2O from modern vehicles to very low levels.

  3. Development of a Highly Efficient Hybrid White Organic-Light-Emitting Diode with a Single Emission Layer by Solution Processing.

    Science.gov (United States)

    Wu, Jun-Yi; Chen, Show-An

    2018-02-07

    We use a mixed host, 2,6-bis[3-(carbazol-9-yl)phenyl]pyridine blended with 20 wt % tris(4-carbazoyl-9-ylphenyl)amine, to lower the hole-injection barrier, along with the bipolar and high-photoluminescence-quantum-yield (Φ p = 84%), blue thermally activated delay fluorescence (TADF) material of 9,9-dimethyl-9,10-dihydroacridine-2,4,6-triphenyl-1,3,5-triazine (DMAC-TRZ) as a blue dopant to compose the emission layer for the fabrication of a TADF blue organic-light-emitting diode (BOLED). The device is highly efficient with the following performance parameters: maximum brightness (B max ) = 57586 cd/m 2 , maximum current efficiency (CE max ) = 35.3 cd/A, maximum power efficiency (PE max ) = 21.4 lm/W, maximum external quantum efficiency (EQE max ) = 14.1%, and CIE coordinates (0.18, 0.42). This device has the best performance recorded among the reported solution-processed TADF BOLEDs and has a low efficiency roll-off: at brightness values of 1000 and 5000 cd/m 2 , its CEs are close, being 35.1 and 30.1 cd/A, respectively. Upon further doping of the red phosphor Ir(dpm)PQ 2 (emission peak λ max = 595 nm) into the blue emission layer, we obtained a TADF-phosphor hybrid white organic-light-emitting diode (T-P hybrid WOLED) with high performance: B max = 43594 cd/m 2 , CE max = 28.8 cd/A, PE max = 18.1 lm/W, and CIE coordinates (0.38, 0.44). This B max = 43594 cd/m 2 is better than that of the vacuum-deposited WOLED with a blue TADF emitter, 10000 cd/m 2 . This is also the first report on a T-P hybrid WOLED with a solution-processed emitting layer.

  4. Application of automobile emission control technology to light piston aircraft engines

    Science.gov (United States)

    Tripp, D.; Kittredge, G.

    1976-01-01

    The possibility was evaluated for achieving the EPA Standards for HC and CO emissions through the use of air-fuel ratio enleanment at selected power modes combined with improved air-fuel mixture preparation, and in some cases improved cooling. Air injection was also an effective approach for the reduction of HC and CO, particularly when combined with exhaust heat conservation techniques such as exhaust port liners.

  5. Determination of light elements concentration in aerosols by X emission induced by deuteron

    International Nuclear Information System (INIS)

    Morales, J.R.; Romo, C.

    1983-01-01

    Absolute concentrations for Al, Si, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe and Cu were obtained in the range from 10 ng/m 3 to 10 4 ng/m 3 in aerosols from Santiago. A 4,2 MeV deuteron beam was used to induce characteristic X-ray emission. It was found that relative abundance of these elements is maintained for days of high and low total suspended particulates. (Author)

  6. Plasmon modes in light emission from silver nanoparticles induced by a scanning tunneling microscope

    Czech Academy of Sciences Publication Activity Database

    Kůsová, Kateřina; Charra, F.; Schull, G.; Pelant, Ivan

    2008-01-01

    Roč. 602, č. 1 (2008), s. 345-348 ISSN 0039-6028 R&D Projects: GA AV ČR IAA1010316; GA MŠk LC510; GA AV ČR IAA1010413 Institutional research plan: CEZ:AV0Z10100521 Keywords : scanning tunneling microscopy * photon emission * plasmons * silver nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.731, year: 2008

  7. Light particle and gamma ray emission measurements in heavy ion reactions. Progress report

    International Nuclear Information System (INIS)

    Petitt, G.A.

    1983-01-01

    Studies of neutron and charged particle emission in heavy ion reactions using the facilities at the HHIRF and the new computer facilities at Georgia State are briefly described. A progress report for 1982 to 1983 is combined with a proposal for work to be performed during 1983 to 1984. Present activities and immediate plans for a run already approved by the Program Advisory Committee of the HHIRF are discussed

  8. Controlling emission and propagation of light with photonic band gap crystals

    NARCIS (Netherlands)

    Yeganegi Dastgerdi, Elahe

    2014-01-01

    In certain three-dimensional crystals, a frequency range exist for all polarizations for which light is not allowed to propagate in any direction, called the 3D photonic band gap: a frequency range where the density of vacuum fluctuations vanishes in an ideal infinitely large and perfect system. The

  9. Entangled-Photon Pair Emission from a Light-Emitting Diode

    International Nuclear Information System (INIS)

    Salter, Cameron L; Stevenson, R Mark; Shields, Andrew J; Farrer, Ian; Nicoll, Christine A; Ritchie, David A

    2011-01-01

    Electrically-driven entangled-photon generation is demonstrated for the first time using a single InAs/GaAs quantum dot embedded in a light emitting diode structure. Under alternating-current injection, we found that the entanglement fidelity was of sufficient quality for quantum information applications such as quantum key distribution.

  10. Light charged particle emission in heavy-ion reactions – What have ...

    Indian Academy of Sciences (India)

    Light charged particles; heavy-ion induced reactions; particle spectra and angular distri- butions; reaction mechanisms. ... ions. At very high energies, the nucleon–nucleon aspects dominate. In the intermediate energies, both the mean field and the nucleon–nucleon aspects play their roles (figure 1). These features in turn ...

  11. Broadly tunable metal halide perovskites for solid-state light-emission applications

    NARCIS (Netherlands)

    Adjokatse, Sampson; Fang, Hong-Hua; Loi, Maria Antonietta

    2017-01-01

    The past two years have witnessed heightened interest in metal-halide perovskites as promising optoelectronic materials for solid-state light emitting applications beyond photovoltaics. Metal-halide perovskites are low-cost solution-processable materials with excellent intrinsic properties such as

  12. Light-absorbing carbon from prescribed and laboratory biomass burning and gasoline vehicle emissions

    Science.gov (United States)

    Carbonaceous aerosols are ubiquitous in the atmosphere and can directly affect Earth’s climate by absorbing and scattering incoming solar radiation. Both field and laboratory measurements have confirmed that biomass burning (BB) is an important primary source of light absor...

  13. First light - II. Emission line extinction, population III stars, and X-ray binaries

    Science.gov (United States)

    Barrow, Kirk S. S.; Wise, John H.; Aykutalp, Aycin; O'Shea, Brian W.; Norman, Michael L.; Xu, Hao

    2018-02-01

    We produce synthetic spectra and observations for metal-free stellar populations and high-mass X-ray binaries in the Renaissance Simulations at a redshift of 15. We extend our methodology from the first paper in the series by modelling the production and extinction of emission lines throughout a dusty and metal-enriched interstellar and circum-galactic media extracted from the simulation, using a Monte Carlo calculation. To capture the impact of high-energy photons, we include all frequencies from hard X-ray to far-infrared with enough frequency resolution to discern line emission and absorption profiles. The most common lines in our sample in order of their rate of occurrence are Ly α, the C IV λλ1548, 1551 doublet, H α, and the Ca II λλλ8498, 8542, 8662 triplet. The best scenario for a direct observation of a metal-free stellar population is a merger between two Population III Galaxies. In mergers between metal-enriched and metal-free stellar populations, some characteristics may be inferred indirectly. Single Population III galaxies are too dim to be observed photometrically at z = 15. Ly α emission is discernible by JWST as an increase in J200w - J277w colour off the intrinsic stellar tracks. Observations of metal-free stars will be difficult, though not impossible, with the next generation of space telescopes.

  14. Autonomous taxis could greatly reduce greenhouse-gas emissions of US light-duty vehicles

    Science.gov (United States)

    Greenblatt, Jeffery B.; Saxena, Samveg

    2015-09-01

    Autonomous vehicles (AVs) are conveyances to move passengers or freight without human intervention. AVs are potentially disruptive both technologically and socially, with claimed benefits including increased safety, road utilization, driver productivity and energy savings. Here we estimate 2014 and 2030 greenhouse-gas (GHG) emissions and costs of autonomous taxis (ATs), a class of fully autonomous shared AVs likely to gain rapid early market share, through three synergistic effects: (1) future decreases in electricity GHG emissions intensity, (2) smaller vehicle sizes resulting from trip-specific AT deployment, and (3) higher annual vehicle-miles travelled (VMT), increasing high-efficiency (especially battery-electric) vehicle cost-effectiveness. Combined, these factors could result in decreased US per-mile GHG emissions in 2030 per AT deployed of 87-94% below current conventionally driven vehicles (CDVs), and 63-82% below projected 2030 hybrid vehicles, without including other energy-saving benefits of AVs. With these substantial GHG savings, ATs could enable GHG reductions even if total VMT, average speed and vehicle size increased substantially. Oil consumption would also be reduced by nearly 100%.

  15. ZnSe Light Emitting Diode Quantum Efficiency and Emission Characterization

    Directory of Open Access Journals (Sweden)

    Sahbudin U.K.

    2016-01-01

    Full Text Available ZnSe has demonstrated as a potential candidate in realizing advance LED in some appications for current and future works that utilize a cheaper preparation technique. Blue and white LEDs have been shown to spread across compound semiconductors. This II-VI compound semiconductor with a direct and wide band gap is used in the study which focused on a preparation and its characterization. The device is developed using a circular chip of ZnSe but only part of the active region is designed to allow shorter computation time. Analyses of the proposed LED are performed in an environment that allows optical transition and nonradiative recombination mechanisms. Voltage variation from 0 V to 1.5 V is maintained throughout the observation. The curent-voltage plot shows the p-n junction or diode behavior with central emissive layer. The two dimensions surface emission rate obtained indicates that voltage increment causes the emission concentration to become higher near the central pcontact. The LED efficiency is assessed in terms of internal quantum efficiency and emitting rate.

  16. Green light emission by InGaN/GaN multiple-quantum-well microdisks

    International Nuclear Information System (INIS)

    Hsu, Yu-Chi; Lo, Ikai; Shih, Cheng-Hung; Pang, Wen-Yuan; Hu, Chia-Hsuan; Wang, Ying-Chieh; Tsai, Cheng-Da; Chou, Mitch M. C.; Hsu, Gary Z. L.

    2014-01-01

    The high-quality In x Ga 1−x N/GaN multiple quantum wells were grown on GaN microdisks with γ-LiAlO 2 substrate by using low-temperature two-step technique of plasma-assisted molecular beam epitaxy. We demonstrated that the hexagonal GaN microdisk can be used as a strain-free substrate to grow the advanced In x Ga 1−x N/GaN quantum wells for the optoelectronic applications. We showed that the green light of 566-nm wavelength (2.192 eV) emitted from the In x Ga 1−x N/GaN quantum wells was tremendously enhanced in an order of amplitude higher than the UV light of 367-nm wavelength (3.383 eV) from GaN

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

    International Nuclear Information System (INIS)

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

    2000-01-01

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

  18. Enhancing the Photoluminescence Emission of Conjugated MEH-PPV by Light Processing

    KAUST Repository

    Botiz, Ioan

    2014-04-09

    We show here that treatment of thin films of conjugated polymers by illumination with light leads to an increase of the intensity of their photoluminescence by up to 42%. The corresponding enhancement of absorbance was much less pronounced. We explain this significant enhancement of photoluminescence by a planarization of the conjugated polymer chains induced by photoexcitations even below the glass transition temperature, possibly due to an increased conjugation length. Interestingly, the photoluminescence remains at the enhanced level for more than 71 h after treatment of the films by illumination with light, likely due to the fact that below the glass transition temperature no restoring force could return the conjugated chains into their initial conformational state. © 2014 American Chemical Society.

  19. Correlation of A-particles emission with the speed of light

    International Nuclear Information System (INIS)

    Abbas, M.

    2004-01-01

    In this phenomenological research, a relation connecting α-particle energy and α-decay half-life for all isotopes emitting α-particles have been achieved, and the experimental data affirmed this tight correlation. Also a relation connecting α-decay rate with the speed of light has been established. Depending on this last relation and the hypothesis of increasing light speed as we go back in time, some mysterious phenomena discovered recently, concerning α-decay radioactivity, have also been interpreted. Thus, the increase of radioactivity as we go back in time was approved; which interpreted the enormous amount of α-particles in some positions on the earth that cannot be interpreted using known laws of radioactivity. (Author)

  20. The synthesis and characterization of Al/Co3O4 magnetic composite pigments with low infrared emissivity and low lightness

    Science.gov (United States)

    Liu, Yunfeng; Xie, Jianliang; Luo, Mei; Jian, Shuai; Peng, Bo; Deng, Longjiang

    2017-06-01

    The main challenge of low infrared emissivity coatings based on aluminum flake lies in finding an efficient method to synthesize the composite pigment with low infrared emissivity and low lightness simultaneously. In this work, we overcome this constraint to some extent, synthesizing a novel Al/Co3O4 magnetic composite pigments with low infrared emissivity and low lightness by thermal cracking and hot flowing method. The results show that the covering area of Co3O4 on the aluminum flake can be tuned by the amount of CoCO3 adding in precursor and the reaction temperature of hot flowing, both of which pay a key factor on the VIS and IR spectral reflectance and magnetic properties. The magnetic Al/Co3O4 composite pigments with low lightness and low infrared emissivity can be obtained at 130 °C for 24 h in hot flowing liquid. The lightness L∗ can be decreased to 69.2, however the infrared emissivity (8-14 μm) is also low to 0.45. Compared with the single Al flakes, Al/Co3O4 magnetic composite pigments present stronger magnetic properties. Therefore, the Al/Co3O4 magnetic composite pigments have offered new choice for the pigments of low infrared emissivity coatings.

  1. Dynamic Control of Light Emission Faster than the Lifetime Limit Using VO2 Phase-Change

    Science.gov (United States)

    2015-10-22

    broadband: in this experiment it covers the S-, C- and L-bands of conventional fibre - optic communication. Furthermore, given the ultra-broadband tuning...cornerstone of optical communication, and as such, governs the overall speed of data transmission. Currently, the two main strategies for modulating...light are direct modulation of the excited emitter population (for example, using semiconductor lasers) and external optical modulation (for example

  2. Controlling light emission from single-photon sources using photonic nanowires

    DEFF Research Database (Denmark)

    Gregersen, Niels; Chen, Yuntian; Mørk, Jesper

    2012-01-01

    The photonic nanowire has recently emerged as an promising alternative to microcavity-based single-photon source designs. In this simple structure, a geometrical effect ensures a strong coupling between an embedded emitter and the optical mode of interest and a combination of tapers and mirrors a...... designs allowing for electrical contacting, polarization control, improved efficiency and simplified fabrication....

  3. Reduction in global warming due to fuel economy improvements and emissions control of criteria pollutants: New US light-duty vehicles (1968--1991)

    International Nuclear Information System (INIS)

    Pitstick, M.E.; Santini, D.J.; Chauhan, H.

    1992-01-01

    This paper explores the impact of US emission controls and fuel economy improvements on the global warming potential (GWP) of new light-duty vehicles. Fuel economy improvements have reduced the GWP of both passenger cars and light-duty trucks by lowering the per mile emissions of carbon dioxide (CO 2 ). Further GWP reductions have been achieved by emission standards for criteria pollutants: carbon monoxide (CO), hydrocarbons (HC), and nitrogen oxides (NO x ). The GWP of a criteria pollutant was calculated by multiplying the emission rate by a relative global warming factor to obtain a CO 2 equivalent emission rate. Both CO 2 and criteria pollutant emission rates per vehicle have decreased substantially for new light-duty vehicles over the period from 1968 to 1991. Over that period, the GWP from CO 2 was reduced by almost 50% in new vehicles by improving fuel economy. In that same time period, the GWP from criteria pollutants from new vehicles was reduced with emission controls by from 80% to 90% depending on the global warming time frame of interest. Consequently, total reductions in the GWP of new passenger cars and light-duty trucks have been on the order of 55 to 75 percent compared to precontrol (before 1968) new vehicles. However, the reduction in GWP caused by emission control of criteria pollutants has been larger than the reduction caused by improved fuel economy (i.e., reduced CO 2 ). The contribution of criteria pollutants to the GWP of precontrol new vehicles was substantial, but their contribution has been reduced significantly due to US emission controls. As a result, the contribution of criteria pollutants to global warming is now much less than the contribution of CO 2 from fuel consumption

  4. Use of a Chamber to Comprehensively Characterise Emissions and Subsequent Processes from a Light-Duty Diesel Engine

    Science.gov (United States)

    Allan, J. D.; Alfarra, M. R. R.; Whitehead, J.; McFiggans, G.; Kong, S.; Harrison, R. M.; Alam, M. S.; Hamilton, J. F.; Pereira, K. L.; Holmes, R. E.

    2014-12-01

    Around 1 in 3 light duty vehicles in the UK use diesel engines, meaning that on-road emissions of particulates, NOx and VOCs and subsequent chemical processes are substantially different to countries where gasoline engines dominate. As part of the Natural Environment Research Council (NERC) Com-Part project, emissions from a diesel engine dynamometer rig representative of the EURO 4 standard were studied. The exhaust was passed to the Manchester aerosol chamber, which consists of an 18 m3 teflon bag and by injecting a sample of exhaust fumes into filtered and chemically scrubbed air, a controllable dilution can be performed and the sample held in situ for analysis by a suite of instruments. The system also allows the injection of other chemicals (e.g. ozone, additional VOCs) and the initiation of photochemistry using a bank of halogen bulbs and a filtered Xe arc lamp to simulate solar light. Because a large volume of dilute emissions can be held for a period of hours, this permits a wide range of instrumentation to be used and relatively slow processes studied. Furthermore, because the bag is collapsible, the entire particulate contents can be collected on a filter for offline analysis. Aerosol microphysical properties are studied using a Scanning Mobility Particle Sizer (SMPS) and Centrifugal Particle Mass Analyser (CPMA); aerosol composition using a Soot Particle Aerosol Mass Spectrometer (SP-AMS), Single Particle Soot Photometer (SP2), Sunset Laboratories OC EC analyser and offline gas- and high performance liquid chromatography (employing advanced mass spectrometry such as ion trap and fourier transform ion cyclotron resonance); VOCs using comprehensive 2D gas chromatography; aerosol optical properties using a Cavity Attenuated Phase Shift Single Scattering Albedo monitor (CAPS-PMSSA), 3 wavelength Photoacoustic Soot Spectrometer (PASS-3) and Multi Angle Absorption Photometer (MAAP); particle hygroscopcity using a Hygroscopicity Tandem Differential Mobility

  5. Red light emission from europium doped zinc sodium bismuth borate glasses

    Science.gov (United States)

    Hegde, Vinod; Viswanath, C. S. Dwaraka; Upadhyaya, Vyasa; Mahato, K. K.; Kamath, Sudha D.

    2017-12-01

    Zinc sodium bismuth borate (ZNBB) glasses doped with different concentrations of europium were prepared by conventional melt quenching method and characterized through the measurements of density, refractive index, X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectra, optical absorption, luminescence and radiative lifetimes. FTIR spectra showed seven characteristic peaks of bismuth and borate functional groups in the range of 400-1600 cm-1. The optical band gap and bonding parameters have been calculated from absorption spectra. Photoluminescence spectra recorded in the visible region with 394 nm excitation are used to calculate the Judd-Ofelt (JO) intensity parameters (Ω2 and Ω4). The JO intensity parameters have been used to calculate the radiative parameters such as branching ratio (β), stimulated emission cross-section (σse), transition probability (A) for the fluorescent level of 5D0→7F2. Decay rates through single exponential are used to calculate the lifetime (τm) of the meta-stable state 5D0 of (Eu3+ ion) these glasses. The radiative parameters measured for all these glasses show 0.7 mol% europium doped zinc sodium bismuth borate glass 5D0→7F2 transition has the potential for red laser applications. The quality of the colour emitted by the present glasses are estimated quantitatively by CIE chromaticity coordinates, which confirms the suitability of these glasses as a red emitting material for field emission technologies and LEDs.

  6. Narrow-band light emission from a single carbon nanotube p-n diode

    Science.gov (United States)

    Kinoshita, Megumi; Mueller, Thomas; Steiner, Mathias; Perebeinos, Vasili; Bol, Ageeth; Farmer, Damon; Avouris, Phaedon

    2010-03-01

    We present the first observation of electroluminescence from electrostatically-generated carbon nanotube (CNT) p-n junctions[1]. While CNT optoelectronics has made much progress in recent years, observations of emission from electrically excited CNT devices have been limited to the high-bias regime and with low efficiency. Furthermore, the resulting broad linewidths are broad, making it difficult to investigate electronic levels and carrier dynamics. We find that p-n junctions allow for better carrier control at lower power inputs, resulting in emission with near-zero threshold, low self-heating and efficiency two to three orders of magnitude greater compared to previous device configurations. This yields higher signal-to-noise ratio and narrower linewidths (down to ˜35 meV) that allows us to identify localized excitonic transitions that have previously been observed only in photoluminescent studies. [1] T. Mueller, M. Kinoshita, M. Steiner, V. Perebeinos, A. Bol, D. Farmer, and Ph. Avouris, Nature Nanotech., web publication, November 15 2009.

  7. Nanoscale semiconductor-insulator-metal core/shell heterostructures: facile synthesis and light emission.

    Science.gov (United States)

    Li, Gong Ping; Chen, Rui; Guo, Dong Lai; Wong, Lai Mun; Wang, Shi Jie; Sun, Han Dong; Wu, Tom

    2011-08-01

    Controllably constructing hierarchical nanostructures with distinct components and designed architectures is an important theme of research in nanoscience, entailing novel but reliable approaches of bottom-up synthesis. Here, we report a facile method to reproducibly create semiconductor-insulator-metal core/shell nanostructures, which involves first coating uniform MgO shells onto metal oxide nanostructures in solution and then decorating them with Au nanoparticles. The semiconductor nanowire core can be almost any material and, herein, ZnO, SnO(2) and In(2)O(3) are used as examples. We also show that linear chains of short ZnO nanorods embedded in MgO nanotubes and porous MgO nanotubes can be obtained by taking advantage of the reduced thermal stability of the ZnO core. Furthermore, after MgO shell-coating and the appropriate annealing treatment, the intensity of the ZnO near-band-edge UV emission becomes much stronger, showing a 25-fold enhancement. The intensity ratio of the UV/visible emission can be increased further by decorating the surface of the ZnO/MgO nanowires with high-density plasmonic Au nanoparticles. These heterostructured semiconductor-insulator-metal nanowires with tailored morphologies and enhanced functionalities have great potential for use as nanoscale building blocks in photonic and electronic applications. This journal is © The Royal Society of Chemistry 2011

  8. Entrance channel dependent light-charged particle emission of the 156Er compound

    International Nuclear Information System (INIS)

    Liang, J.F.; Bierman, J.D.; Kelly, M.P.; Sonzogni, A.A.; Vandenbosch, R.; van Schagen, J.P.S.

    1996-01-01

    Light-charged particle decay from the 156 Er compound nucleus, populated by 12 C+ 144 Sm and 60 Ni+ 96 Zr at the same excitation energy, were measured in coincidence with the evaporation residues. The high energy slope of charged particle spectra for the 60 Ni-induced reaction is steeper than for the 12 C-induced reaction. Model calculations including particle evaporation during compound nucleus formation result in good agreement with the data. This suggests that the difference in the charged particle spectra between the two entrance channels is due to a longer formation time in the 60 Ni-induced reaction. 14 refs., 3 figs

  9. Modulating emission intensity of GaN-based green light emitting diodes on c-plane sapphire

    International Nuclear Information System (INIS)

    Du, Chunhua; Ma, Ziguang; Zhou, Junming; Lu, Taiping; Jiang, Yang; Jia, Haiqiang; Liu, Wuming; Chen, Hong

    2014-01-01

    The asymmetric dual-wavelength (green/blue) coupled InGaN/GaN multiple quantum wells were proposed to modulate the green emission intensity. Electroluminescent measurements demonstrate the conspicuous increment of the green light intensity by decreasing the coupled barrier thickness. This was partly attributed to capture of more carriers when holes tunnel across the thinner barrier from the blue quantum wells, as a hole reservoir, to the green quantum wells. While lower effective barrier height of the blue quantum wells benefits improved hole transportation from p-GaN to the active region. Efficiency droop of the green quantum wells was partially alleviated due to the enhanced injection efficiency of holes

  10. Significant increase of light emission efficiency by in situ site-selective etching of InGaN quantum wells

    Science.gov (United States)

    Fang, Zhilai

    2009-07-01

    An indium post-treatment of the InGaN epilayers was employed for InGaN-to-GaN interface modification. We find that the treatment could lead to selective etching of the InGaN epilayers around threading dislocations (TDs) due to preferential etching of the chemically active step-correlated TDs and formation of indium-rich InGaN nanostructures on the smooth InGaN surface. The intentionally formed V-shaped pits by site-selective etching of the InGaN epilayers resulted in an increased surface potential barrier at the pit sidewalls due to the relatively thin InGaN single quantum well. The increased energy bandgap of the InGaN active layers around the TDs cores caused the lateral carrier confinement away from nonradiative recombination at the defects and thus significantly enhanced the light emission efficiency.

  11. Influence of surfactant on dynamics of photoinduced motions and light emission of a dye-doped deoxyribonucleic acid

    Science.gov (United States)

    Sznitko, Lech; Parafiniuk, Kacper; Miniewicz, Andrzej; Rau, Ileana; Kajzar, Francois; Niziol, Jacek; Hebda, Edyta; Pielichowski, Jan; Sahraoui, Bouchta; Mysliwiec, Jaroslaw

    2013-10-01

    Pure deoxyribonucleic acid (DNA) is known to be soluble in water only and exhibits poor temperature stability. In contrary, it is well known that the complex of DNA - with cetyltrimethyl ammonium (CTMA) is insoluble in water but soluble in alcohols and can be processed into very good optical quality thin films by solution casting or spin deposition. Despite the success of DNA-CTMA, there is still need for new cationic surfactants which would extend the range of available solvents for DNA complex. We test and present experimental results of influence of new surfactants replacing CTMA in the DNA complex and based on benzalkonium chloride (BA) and didecyldimethylammonium chloride (DDCA) on their optical properties. Particularly, we were interested in all optical switching and light generation in amplified spontaneous emission process in these materials.

  12. Power consumption, discharge capacitance and light emission as measures for thrust production of dielectric barrier discharge plasma actuators

    International Nuclear Information System (INIS)

    Kriegseis, J.; Grundmann, S.; Tropea, C.

    2011-01-01

    A new procedure of determining the time resolved capacitance of a plasma actuator during operation is introduced, representing a simple diagnostic tool that provides insight into the phenomenological behavior of plasma actuators. The procedure is demonstrated by presenting example correlations between consumed electrical energy, size of the plasma region, and the operating voltage. It is shown that the capacitance of a plasma actuator is considerably increased by the presence of the plasma; hence a system that has previously been impedance matched can be considerably de-tuned when varying the operating voltage of the actuator. Such information is fundamental for any attempts to increase the energy efficiency of plasma-actuator systems. A combined analysis of the capacitance, light emission, size of the plasma region, force production, and power consumption is presented.

  13. Radiative emission of neutrino pairs in atoms and light sterile neutrinos

    Directory of Open Access Journals (Sweden)

    D.N. Dinh

    2015-03-01

    Full Text Available The process of Radiative Emission of Neutrino Pair (RENP in atoms is sensitive to the absolute neutrino mass scale, the type of spectrum neutrino masses obey and the nature – Dirac or Majorana – of massive neutrinos. We analyse the possibility to test the hypothesis of existence of neutrinos with masses at the eV scale coupled to the electron in the weak charged lepton current in an RENP experiment. The presence of eV scale neutrinos in the neutrino mixing is associated with the existence of sterile neutrinos which mix with the active flavour neutrinos. At present there are a number of hints for active–sterile neutrino oscillations driven by Δm2∼1 eV2. We perform a detailed analysis of the RENP phenomenology within the “3+1” scheme with one sterile neutrino.

  14. Enhanced blue light emission in transparent ZnO:PVA nanocomposite free standing polymer films.

    Science.gov (United States)

    Karthikeyan, B; Pandiyarajan, T; Mangalaraja, R V

    2016-01-05

    ZnO:PVA nanocomposite films were prepared and their fluorescence and time resolved photoluminescence properties were discussed. X-ray diffraction and infrared spectroscopy results confirmed the ZnO:PVA interaction. Optical absorption spectra showed two bands at 280 and 367nm which were ascribed to PVA and excitonic absorption band, respectively. Fluorescence spectra showed that the blue emission of ZnO was enhanced about tenfold through chemical interface electron transfer. The electron transfer from ZnO to PVA and its decay dynamics were experimentally analyzed through time resolved fluorescence measurements. The study revealed that the excited electrons found pathway through PVA to ground state which was slower than the pure ZnO nanoparticles. Copyright © 2015. Published by Elsevier B.V.

  15. Study of the light particle emission in the transition region of mechanisms on SARA

    International Nuclear Information System (INIS)

    Guinet, D.

    1984-01-01

    The results of one of the first experiments on SARA are given. 14 N+ 27 Al reaction with a 420 MeV Nitrogen beams has been studied. The experimantal techniques, peculiarly a simple study of the CSI (Na) and BGO crystals, are reported. Then the experimental results are presented, reaction mechanism are described and analyzed. We try to fit the fragmentation process with the Goldhaber and Friedman models. the isotope production for Z=1, 2 is analyzed in the frame of the coalescence model and of the hot liquid nuclear matter drop model. Our exclusive measurements bring some new informations about the different mechanisms origin. To conclude, a code coupling reaction dynamics and preequilibrium emission is described and results are compared with the experimental data [fr

  16. Light emissions from LiNbO sub 3 /SiO sub 2 /Si structures

    CERN Document Server

    Wu, X L; Tang, N; Deng, S S; Bao, X M

    2003-01-01

    LiNbO sub 3 (LN) films with a high degree of (006) texture were deposited on Si-based dense SiO sub 2 layers by pulsed laser deposition. After annealing, the LN/SiO sub 2 /Si structures were revealed to have ultraviolet-, green-, and red-emitting properties related to self-trapped excitons and E' defect pairs in the SiO sub 2 surface, which are induced by the photorefractive effect of the LN films. The emission wavelength can be tuned by introducing different dopants into the LN films. Waveguiding properties of the structures were demonstrated. The results obtained indicate that the LN/SiO sub 2 /Si structures could be expected to have important applications in modern optoelectronic integration. (letter to the editor)

  17. High-efficiency white organic light-emitting devices with a non-doped yellow phosphorescent emissive layer

    Energy Technology Data Exchange (ETDEWEB)

    Zhao Juan; Yu Junsheng, E-mail: jsyu@uestc.edu.cn; Hu Xiao; Hou Menghan; Jiang Yadong

    2012-03-30

    Highly efficient phosphorescent white organic light-emitting devices (PHWOLEDs) with a simple structure of ITO/TAPC (40 nm)/mCP:FIrpic (20 nm, x wt.%)/bis[2-(4-tertbutylphenyl)benzothiazolato-N,C{sup 2} Prime ] iridium (acetylacetonate) (tbt){sub 2}Ir(acac) (y nm)/Bphen (30 nm)/Mg:Ag (200 nm) have been developed, by inserting a thin layer of non-doped yellow phosphorescent (tbt){sub 2}Ir(acac) between doped blue emitting layer (EML) and electron transporting layer. By changing the doping concentration of the blue EML and the thickness of the non-doped yellow EML, a PHWOLED comprised of higher blue doping concentration and thinner yellow EML achieves a high current efficiency of 31.7 cd/A and Commission Internationale de l'Eclairage coordinates of (0.33, 0.41) at a luminance of 3000 cd/m{sup 2} could be observed. - Highlights: Black-Right-Pointing-Pointer We introduce a simplified architecture for phosphorescent white organic light-emitting device. Black-Right-Pointing-Pointer The key concept of device fabrication is combination of doped blue emissive layer (EML) with non-doped ultra-thin yellow EML. Black-Right-Pointing-Pointer Doping concentration of the blue EML and thickness of the yellow EML are sequentially adjusted. Black-Right-Pointing-Pointer High device performance is achieved due to improved charge carrier balance as well as two parallel emission mechanisms in the EMLs.

  18. Effect of mid-term drought on Quercus pubescens BVOCs' emission seasonality and their dependency on light and/or temperature

    Science.gov (United States)

    Saunier, Amélie; Ormeño, Elena; Boissard, Christophe; Wortham, Henri; Temime-Roussel, Brice; Lecareux, Caroline; Armengaud, Alexandre; Fernandez, Catherine

    2017-06-01

    Biogenic volatile organic compounds (BVOCs) emitted by plants represent a large source of carbon compounds released into the atmosphere, where they account for precursors of tropospheric ozone and secondary organic aerosols. Being directly involved in air pollution and indirectly in climate change, understanding what factors drive BVOC emissions is a prerequisite for modeling their emissions and predict air pollution. The main algorithms currently used to model BVOC emissions are mainly light and/or temperature dependent. Additional factors such as seasonality and drought also influence isoprene emissions, especially in the Mediterranean region, which is characterized by a rather long drought period in summer. These factors are increasingly included in models but only for the principal studied BVOC, namely isoprene, but there are still some discrepancies in estimations of emissions. In this study, the main BVOCs emitted by Quercus pubescens - isoprene, methanol, acetone, acetaldehyde, formaldehyde, MACR, MVK and ISOPOOH (these three last compounds detected under the same m/z) - were monitored with a PTR-ToF-MS over an entire seasonal cycle during both in situ natural and amplified drought, which is expected with climate change. Amplified drought impacted all studied BVOCs by reducing emissions in spring and summer while increasing emissions in autumn. All six BVOCs monitored showed daytime light and temperature dependencies while three BVOCs (methanol, acetone and formaldehyde) also showed emissions during the night despite the absence of light under constant temperature. Moreover, methanol and acetaldehyde burst in the early morning and formaldehyde deposition and uptake were also punctually observed, which were not assessed by the classical temperature and light models.

  19. Blue Phosphorescent Organic Light-Emitting Devices with the Emissive Layer of mCP:FCNIr(pic

    Directory of Open Access Journals (Sweden)

    Ji Geun Jang

    2012-01-01

    Full Text Available New high-efficiency blue-light-emitting phosphorescent devices with 300 Å-thick emissive layer of N,N′-dicarbazolyl-3,5-benzene [mCP] doped with 10 vol.% bis[(3,5-difluoro-4-cyanophenylpyridine]iridium picolinate [FCNIr(pic] were fabricated with the different treatments of hole and electron transport layers. In the experiments, a single layer of 1,1-bis-(di-4-polyaminophenylcyclohexane [TAPC] and a double layer of N,N′-di(1-naphthyl-N,N′-diphenylbenzidine [NPB] and mCP were used as hole transport layers (HTLs. In addition, 500 Å-thick double layers of tris-[3-(3-pyridylmesityl]borane [3TPYMB] and 4,7-diphenyl-1,10-phenanthroline [Bphen] were used as electron transport layers (ETLs with various thickness combination of 3TPYMB/Bphen. Among the fabricated devices, the one using TAPC as an HTL and 3TPYMB(100 Å/Bphen(400 Å as an ETL showed best electroluminescent characteristics with a maximum quantum efficiency of 13.3% and a luminance of 950 cd/m2 at 10 V. The color coordinates were (0.14, 0.22 on the Commission Internationale de I'Eclairage (CIE chart, and the electroluminescent spectra showed the double-peak emissions at 458 nm and 483 nm.

  20. Ca²⁺ signal contributing to the synthesis and emission of monoterpenes regulated by light intensity in Lilium 'siberia'.

    Science.gov (United States)

    Hu, Zenghui; Li, Tianjiao; Zheng, Jian; Yang, Kai; He, Xiangfeng; Leng, Pingsheng

    2015-06-01

    The floral scent is an important part of plant volatile compounds, and is influenced by environmental factors. The emission of monoterpenes of Lilium 'siberia' is regulated by light intensity, but the mechanism is large unknown. In this study, the expression of Li-mTPS, a monoterpene synthase gene in the tepals of Lilium 'siberia', and net Ca(2+) flux were investigated after exposure to different levels of light intensity (0, 100, 300, 600, 1000, and 1500 μmol m(-2) s(-1)). Moreover the effect of LaCl3 and ethylene glycol-bis-(2-aminoethylether)-N,N,N',N'-tetraacetic acid (EGTA) on the Li-mTPS expression, monoterpene emission, and net Ca(2+) flux were examined at 600 μmol m(-2) s(-1). The results showed that along with the enhancement of light intensity, the expression level of Li-mTPS increased gradually, and the net Ca(2+) influx was also enhanced showing a similar pattern. It was found that LaCl3 and EGTA effectively inhibited the increase in expression of Li-mTPS and the net Ca(2+) influx induced by light treatment. Moreover, the release amounts of monoterpenes decreased significantly after treatment with LaCl3 and EGTA. So it can be concluded that Ca(2+) signal contributed to the biosynthesis and emission of monoterpenes regulated by light intensity in Lilium 'siberia' tepals. The increased light intensity firstly triggered the Ca(2+) influx to cytoplasm, and then the gene expression of monoterpene synthases downstream was activated to regulate the biosynthesis and emission of monoterpenes. But in the signaling pathway other mechanisms were thought to be involved in the emission of monoterpenes regulated by light intensity, which need to be investigated in future research. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  1. Progress towards Spin-Based Light Emission in Group IV Semiconductors

    Directory of Open Access Journals (Sweden)

    Sebastiano De Cesari

    2017-03-01

    Full Text Available Spin-optoelectronics is an emerging technology in which novel and advanced functionalities are enabled by the synergetic integration of magnetic, optical and electronic properties onto semiconductor-based devices. This article reviews the possible implementation and convergence of spintronics and photonics concepts on group IV semiconductors: the core materials of mainstream microelectronics. In particular, we describe the rapid pace of progress in the achievement of lasing action in the notable case of Ge-based heterostructures and devote special attention to the pivotal role played by optical investigations in advancing the understanding of the rich spin physics of group IV materials. Finally, we scrutinize recent developments towards the monolithic integration on Si of a new class of spin-based light emitting devices having prospects for applications in fields such as cryptography and interconnects.

  2. Strong spectral variation of biomass smoke light absorption and single scattering albedo observed with a novel dual-wavelength photoacoustic instrument

    Science.gov (United States)

    Kristin Lewis; William P. Arnott; Hans Moosmuller; Cyle E. Wold

    2008-01-01

    A dual-wavelength photoacoustic instrument operating at 405 and 870 nm was used during the 2006 Fire Lab at Missoula Experiment to measure light scattering and absorption by smoke from the combustion of a variety of biomass fuels. Simultaneous measurements of aerosol light scattering by reciprocal nephelometry within the instrument's acoustic resonator accompany...

  3. Long-term greenhouse gas emission and petroleum reduction goals: Evolutionary pathways for the light-duty vehicle sector

    International Nuclear Information System (INIS)

    Kromer, Matthew A.; Bandivadekar, Anup; Evans, Christopher

    2010-01-01

    To meet long-term environmental and energy security goals, the United States must reduce petroleum use in the light-duty vehicle fleet by 70% and greenhouse gas emissions by a factor of ten compared to business-as-usual growth projections for the year 2050. A wedge-based approach was used to quantify the scope of the problem in real terms, and to develop options for meeting mid-century targets. Four mitigation mechanisms were considered: (1) improvements in near-term vehicle technologies; (2) emphasis on low-carbon biofuels; (3) de-carbonization of the electric grid; and (4) demand-side travel-reduction initiatives. Projections from previous studies were used to characterize the potential of individual mitigation mechanisms, which were then integrated into a light-duty vehicle fleet model; particular emphasis was given to systemic constraints on scale and rates of change. Based on these projections, two different greenhouse gas (GHG) mitigation implementation plans were considered ('evolutionary' and 'aggressive'). Fleet model projections indicate that both the evolutionary and aggressive approaches can effectively end US dependence on foreign oil, but achieving an 80% GHG reduction requires changes that extend significantly beyond even the aggressive case, which was projected to achieve a 65% reduction.

  4. Electrically driven quantum light emission in electromechanically tuneable photonic crystal cavities

    Science.gov (United States)

    Petruzzella, M.; Pagliano, F. M.; Zobenica, Ž.; Birindelli, S.; Cotrufo, M.; van Otten, F. W. M.; van der Heijden, R. W.; Fiore, A.

    2017-12-01

    A single quantum dot deterministically coupled to a photonic crystal environment constitutes an indispensable elementary unit to both generate and manipulate single-photons in next-generation quantum photonic circuits. To date, the scaling of the number of these quantum nodes on a fully integrated chip has been prevented by the use of optical pumping strategies that require a bulky off-chip laser along with the lack of methods to control the energies of nano-cavities and emitters. Here, we concurrently overcome these limitations by demonstrating electrical injection of single excitonic lines within a nano-electro-mechanically tuneable photonic crystal cavity. When an electrically driven dot line is brought into resonance with a photonic crystal mode, its emission rate is enhanced. Anti-bunching experiments reveal the quantum nature of these on-demand sources emitting in the telecom range. These results represent an important step forward in the realization of integrated quantum optics experiments featuring multiple electrically triggered Purcell-enhanced single-photon sources embedded in a reconfigurable semiconductor architecture.

  5. Effects of preheating on diaspore: Modifications in colour centres, structure and light emission

    Science.gov (United States)

    Garcia-Guinea, J.; Correcher, V.; Rubio, J.; Valle-Fuentes, F. J.

    2005-07-01

    The thermal properties and thermal stability of diaspore-corundum (AlOOH Al2O3), from Goian (Pontevedra, Spain) were studied by means of differential thermal analysis (DTA), thermogravimetry (TG), high temperature X-ray diffraction (HTXRD) and thermally stimulated luminescence (TL) techniques. The samples were annealed to link the combined effect of (i) dehydroxylation, (ii) oxidation reduction of chromophores (Mn 0.5%, Fe2O3 0.12%, TiO2 0.021% and Cr 80 ppm) determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and (iii) phase transitions whilst sample heating (i.e. α-AlOOH→α‧-Al2P3→α-Al2O3). The blue colour of diaspore, attributed to the Ti4+ Fe2+ intervalence-charge-transfer mechanism, turns to white (circa 500 °C) in good agreement with the DTA endothermic peak (dehydroxylation). The coexistence of α-AlOOH and α‧-Al2P3 phases has been detected by in situ HTXRD and could be correlated to the thermoluminescence tests performed on preheated aliquots (up to 500 °C).

  6. Optimized doping concentration of manganese in zinc sulfide nanoparticles for yellow-orange light emission

    Energy Technology Data Exchange (ETDEWEB)

    Cao Jian [Key Laboratory of Excited State Physics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Eastern Nan-Hu Road, Changchun 130033 (China); Graduate School of the Chinese Academy of Sciences, Beijing 100049 (China); Yang Jinghai, E-mail: jhyang1@jlnu.edu.c [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Key Laboratory of Excited State Physics, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Eastern Nan-Hu Road, Changchun 130033 (China); Zhang Yongjun; Yang Lili; Wang Yaxin; Wei Maobin; Liu Yang; Gao Ming; Liu Xiaoyan [Institute of Condensed State Physics, Jilin Normal University, Siping 136000 (China); Xie Zhi [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei, Anhui 230029 (China)

    2009-11-03

    Nanocrystalline samples of ZnS and Zn{sub 1-x}Mn{sub x}S were synthesized by the solvothermal method without any surface-active agents and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), near-edge X-ray-absorption fine structure technique (XANES), photoluminescence (PL) and UV-vis. The results showed that the Mn{sup 2+} ions were substitutionally incorporated into the ZnS host and the size of the particles was decreased as the Mn doped-ratio increased. The yellow-orange emission from the Mn{sup 2+4}T{sub 1}-{sup 6}A{sub 1} transition was observed in the PL spectra, the peak intensity ratio of which to that of sulfur vacancies increased with the increase of the Mn{sup 2+} concentration, and showed a maximum when the concentration of Mn{sup 2+} was kept at 3%.

  7. Assessing Rates of Global Warming Emissions from Port- Fuel Injection and Gasoline Direct Injection Engines in Light-Duty Passenger Vehicles

    Science.gov (United States)

    Short, D.; , D., Vi; Durbin, T.; Karavalakis, G.; Asa-Awuku, A. A.

    2013-12-01

    Passenger vehicles are known emitters of climate warming pollutants. CO2 from automobile emissions are an anthropogenic greenhouse gas (GHG) and a large contributor to global warming. Worldwide, CO2 emissions from passenger vehicles are responsible for 11% of the total CO2 emissions inventory. Black Carbon (BC), another common vehicular emission, may be the second largest contributor to global warming (after CO2). Currently, 52% of BC emissions in the U.S are from the transportation sector, with ~10% originating from passenger vehicles. The share of pollutants from passenger gasoline vehicles is becoming larger due to the reduction of BC from diesel vehicles. Currently, the majority of gasoline passenger vehicles in the United States have port- fuel injection (PFI) engines. Gasoline direct injection (GDI) engines have increased fuel economy compared to the PFI engine. GDI vehicles are predicted to dominate the U.S. passenger vehicle market in the coming years. The method of gasoline injection into the combustion chamber is the primary difference between these two technologies, which can significantly impact primary emissions from light-duty vehicles (LDV). Our study will measure LDV climate warming emissions and assess the impact on climate due to the change in U.S vehicle technologies. Vehicles were tested on a light- duty chassis dynamometer for emissions of CO2, methane (CH4), and BC. These emissions were measured on F3ederal and California transient test cycles and at steady-state speeds. Vehicles used a gasoline blend of 10% by volume ethanol (E10). E10 fuel is now found in 95% of gasoline stations in the U.S. Data is presented from one GDI and one PFI vehicle. The 2012 Kia Optima utilizes GDI technology and has a large market share of the total GDI vehicles produced in the U.S. In addition, The 2012 Toyota Camry, equipped with a PFI engine, was the most popular vehicle model sold in the U.S. in 2012. Methane emissions were ~50% lower for the GDI technology

  8. Technologies and policies for controlling greenhouse gas emissions from the U. S. automobile and light truck fleet.

    Energy Technology Data Exchange (ETDEWEB)

    Plotkin, S.

    1999-01-01

    The message conveyed by the above discussion is that there are no shortages of technologies available to improve the fuel efficiency of the U.S. fleet of autos and light trucks. It clearly is technically feasible to improve greatly the fuel economy of the average new light-duty vehicle. Many of these technologies require tradeoffs, however, that manufacturers are unwilling or (as yet) unable to make in today's market and regulatory environment. These tradeoffs involve higher costs (that might be reduced substantially over time with learning and economies of scale), technical risk and added complexity, emissions concerns (especially for direct injection engines, and especially with respect to diesel engine technology), and customer acceptance issues. Even with current low U.S. oil prices, however, many of these technologies may find their way into the U.S. market, or increase their market share, as a consequence of their penetration of European and Japanese markets with their high gasoline prices. Automotive technology is ''fungible'' that is, it can be easily transported from one market to another. Nevertheless, it probably is unrealistic to expect substantial increases in the average fuel economy of the U.S. light-duty fleet without significant changes in the market. Without such changes, the technologies that do penetrate the U.S. market are more likely to be used to increase acceleration performance or vehicle structures or enable four wheel drive to be included in vehicles without a net mpg penalty. In other words, technology by itself is not likely to be enough to raise fleet fuel economy levels - this was the conclusion of the 1995 Ailomar Conference on Energy and Sustainable Transportation, organized by the Transportation Research Board's Committees on Energy and Alternative Fuels, and it is one I share.

  9. Global Assessment of Hydrogen Technologies - Task 2 Report Comparison of Performance and Emissions from Near-Term Hydrogen Fueled Light Duty Vehicles

    Energy Technology Data Exchange (ETDEWEB)

    Fouad, Fouad H.; Peters, Robert W.; Sisiopiku, Virginia P.; Sullivan Andrew J.; Ng, Henry K.; Waller, Thomas

    2007-12-01

    An investigation was conducted on the emissions and efficiency from hydrogen blended compressed natural gas (CNG) in light duty vehicles. The different blends used in this investigation were 0%, 15%, 30%, 50%, 80%, 95%, and ~100% hydrogen, the remainder being compressed natural gas. The blends were tested using a Ford F-150 and a Chevrolet Silverado truck supplied by Arizona Public Services. Tests on emissions were performed using four different driving condition tests. Previous investigation by Don Karner and James Frankfort on a similar Ford F-150 using a 30% hydrogen blend showed that there was substantial reduction when compared to gasoline in carbon monoxide (CO), nitrogen oxide (NOx), and carbon dioxide (CO2) emissions while the reduction in hydrocarbon (HC) emissions was minimal. This investigation was performed using different blends of CNG and hydrogen to evaluate the emissions reducing capabilities associated with the use of the different fuel blends. The results were then tested statistically to confirm or reject the hypotheses on the emission reduction capabilities. Statistically analysis was performed on the test results to determine whether hydrogen concentration in the HCNG had any effect on the emissions and the fuel efficiency. It was found that emissions from hydrogen blended compressed natural gas were a function of driving condition employed. Emissions were found to be dependent on the concentration of hydrogen in the compressed natural gas fuel blend.

  10. Modelling of NO{sub x} emission factors from heavy and light-duty vehicles equipped with advanced aftertreatment systems

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, M.L.M., E-mail: monalisa@unifor.br [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Silva, C.M. [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Moreno-Tost, R. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Farias, T.L. [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Jimenez-Lopez, Antonio [IDMEC - Institute of Mechanical Engineering, Instituto Superior Tecnico, Technical University of Lisbon, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain); Rodriguez-Castellon, E. [Departamento de Quimica Inorganica, Cristalografia y Mineralogia, Unidad Asociada al Instituto de Catalisis, CSIC, Universidad de Malaga, Campus de Teatinos, 29071 Malaga (Spain)

    2011-08-15

    Highlights: {yields} Alternative SCR materials. {yields} Catalysts used in heavy-duty vehicles are based on V{sub 2}O{sub 5}-WO{sub 3}-TiO{sub 2}. {yields}Zeolites containing transition metal ions as catalysts for urea SCR has increased. {yields} FeZSM5 catalyst can be a possible candidate as far as pollutants regulation is considered. {yields} Regarding N{sub 2}O emissions mordenite based SCR do not emit this pollutant. - Abstract: NO{sub x} emission standards are becoming stringiest over the world especially for heavy-duty vehicles. To comply with current and future regulations some vehicle manufacturers are adopting exhaust aftertreatment systems known as Selective Catalytic Reduction (SCR). The catalysts are based on Vanadium (Va) and the reductant agent based on ammonia. However, Va is listed on the California Proposition 65 List as potentially causing cancer and alternatives are being studied. This paper presents a model based on neural networks that integrated with a road vehicle simulator allows to estimate NO{sub x} emission factors for different powertrain configurations, along different driving conditions, and covering commercial, zeolite and mordenite alternatives as the base monolith for SCR. The research included the experimental study of copper based and iron based zeolites (ZSM5 and Cuban natural mordenite). The response of NO{sub x} conversion efficiency was monitored in a laboratory for varying space velocity, oxygen, sulfur, water, NO{sub x} and SO{sub 2} emulating the conditions of a Diesel engine exhaust along a trip. The experimental data was used for training neural networks and obtaining a mathematical correlation between the outputs and inputs of the SCR system. The developed correlation was integrated with ADVISOR road vehicle simulator to obtain NO{sub x} emission factors and to test each SCR system installed on light-duty and heavy-duty vehicles for standardized driving cycles and real measured driving cycles. Despite having lower NO

  11. Green light emission in aluminum oxide powders doped with different terbium concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Mariscal B, L; Falcony, C. [IPN, Centro de Investigacion y de Estudios Avanzados, 07360 Ciudad de Mexico (Mexico); Carmona T, S.; Murrieta, H.; Sanchez A, M. A. [UNAM, Instituto de Fisica, 04510 Ciudad de Mexico (Mexico); Vazquez A, R. [IPN, Escuela Superior de Computo, 07738 Ciudad de Mexico (Mexico); Garcia R, C. M., E-mail: mariscal2005@gmail.com [UNAM, Facultad de Ciencias, 04510 Ciudad de Mexico (Mexico)

    2016-11-01

    Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, X-ray diffraction and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622 nm, corresponding to {sup 5}D{sub 4} → {sup 7}F{sub 6}, {sup 5}D{sub 4} → {sup 7}F{sub 5}, {sup 5}D{sub 4} → {sup 7}F{sub 4} and {sup 5}D{sub 4} → {sup 7}F{sub 3}, respectively when they are excited with λ{sub exc} = 380 nm wavelength at room temperature. The results of X-ray diffraction show the presence of α-Al{sub 2}O{sub 3} phases with peaks located at 2θ = 25.78, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the δ-Al{sub 2}O-3 phase 2θ = 32.82, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100 degrees Celsius. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina. (Author)

  12. Emission Channeling Studies on the Behaviour of Light Alkali Atoms in Wide-Band-Gap Semiconductors

    CERN Multimedia

    Recknagel, E; Quintel, H

    2002-01-01

    % IS342 \\\\ \\\\ A major problem in the development of electronic devices based on diamond and wide-band-gap II-VI compound semiconductors, like ZnSe, is the extreme difficulty of either n- or p-type doping. The only reports of successful n-type doping of diamond involves ion implanted Li, which was found to be an intersititial donor. Recent theoretical calculations suggest that Na, P and N dopant atoms are also good candidates for n-type doping of diamond. No experimental evidence has been obtained up to now, mainly because of the complex and partly unresolved defect situation created during ion implantation, which is necessary to incorporate potential donor atoms into diamond. \\\\ \\\\In the case of ZnSe, considerable effort has been invested in trying to fabricate pn-junctions in order to make efficient, blue-light emitting diodes. However, it has proved to be very difficult to obtain p-type ZnSe, mainly because of electrical compensation related to background donor impurities. Li and Na are believed to be ampho...

  13. Organic Pollutants Removal from Petroleum Refinery Wastewater with Nanotitania Photocatalyst and UV Light Emission

    Directory of Open Access Journals (Sweden)

    Javad Saien

    2012-01-01

    Full Text Available A real petroleum refinery wastewater, containing a range of aliphatic and aromatic organic compounds, was treated using nanotitania particles, as the photocatalyst in UV/TiO2 process. Samples were collected from the inlet point of the biological treatment unit. A conic-shape, circulating, and upward mixing reactor, without dead zone, was employed. The light source was an immersed mercury UV lamp (400 W, 200–550 nm. Optimal suspended catalyst concentration, fluid pH, and temperature were obtained at amounts of near 100 mg·L−1, 3 and 45°C, respectively. A maximum reduction in chemical oxygen demand (COD of more than 78% was achieved after about 120 min and, hence, 72% after only 90 min. Significant pollutant degradation was also relevant under other conditions. The identification analysis of the organic pollutants, provided by means of a GC/MS, equipped with headspace injection technique, showed that different petroleum compounds were degraded with high efficiencies.

  14. Trends in the emissions of Volatile Organic Compounds (VOCs) from light-duty gasoline vehicles tested on chassis dynamometers in Southern California

    Science.gov (United States)

    Pang, Yanbo; Fuentes, Mark; Rieger, Paul

    2014-02-01

    We present fleet average VOC emission rate trends for the longest running in-use light-duty gasoline Vehicle Surveillance Program (VSP) in Southern California. Tailpipe emissions data from a limited number of vehicles tested as part of the VSP show that the 2003 fleet average emissions decreased by about 80% for most VOCs relative to the 1995 fleet. Vehicle evaporative emission rates decreased more than 90% for most compounds from the 1999 to the 2003 fleet. Tailpipe benzene-normalized emission rate ratios for most compounds were relatively stable. Evaporative emission rate ratios and weight percentages have changed significantly from the 1999 fleet to the 2003 fleet indicating a significant change in the evaporative emission species patterns. The tailpipe NMHC (Non-Methane HydroCarbon) emission reductions observed between the 1995 fleet and the 2003 fleet likely resulted from the retirement of non-catalyst vehicles in the fleets (49%) and the combined effect of the turn-over of catalyst-equipped vehicles and switch to Phase III gasoline (27%). Our results are consistent with those observed in the Swiss tunnel study. Benzene-normalized emission rate ratios for C2 compounds, aldehydes, and 1,3 butadiene are much higher in tailpipe exhaust than those in evaporative emissions. C4-C5 hydrocarbon ratios in evaporative emissions are much higher than those in exhaust. C8 aromatic compound ratios are comparable for tailpipe and evaporative emissions (hot-soak). Such ratio differences can be used to estimate the relative contributions of vehicle exhaust and evaporative emission to ambient VOCs. The contribution of emissions from malfunctioning vehicles to total fleet emissions increased from 16% to 32% for the 1995 fleet to the 2003 fleet even though the percentage of malfunctioning vehicles in the fleet decreased from 10% to 5%. Most malfunctioning vehicles are vehicles that are at least 10 years old and generally have higher acetylene emission rate ratios. The effective

  15. Highly efficient red phosphorescent organic light-emitting diodes based on solution processed emissive layer

    International Nuclear Information System (INIS)

    Liu, Baiquan; Xu, Miao; Tao, Hong; Ying, Lei; Zou, Jianhua; Wu, Hongbin; Peng, Junbiao

    2013-01-01

    Highly efficient red phosphorescent organic polymer light-emitting diodes (PhOLEDs) were fabricated based on a solution-processed small-molecule host 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) by doping an iridium complex, tris(1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine)iridium (III) (Ir(MPCPPZ) 3 ). A hole blocking layer 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI) with a function of electron transport was thermally deposited onto the top of CBP layer. The diode with the structure of ITO/PEDOT:PSS (50 nm)/CBP:Ir(MPCPPZ) 3 (55 nm)/TPBI (30 nm)/Ba (4 nm)/Al (120 nm) showed an external quantum efficiency (QE ext ) of 19.3% and luminous efficiency (LE) of 18.3 cd/A at a current density of 0.16 mA/cm 2 , and Commission International de I'Eclairage (CIE) coordinates of (0.607, 0.375). It was suggested that the diodes using TPBI layer exhibited nearly 100% internal quantum efficiency and one order magnitude enhanced LE or QE ext efficiencies. -- Highlights: • Efficient red PhOLEDs based on a solution-processed small-molecule host were fabricated. • By altering volume ratio of chloroform/chlorobenzene solvent, we got best film quality of CBP. • EQE of the diode was 19.3%, indicating nearly 100% internal quantum yield was achieved

  16. Highly efficient red phosphorescent organic light-emitting diodes based on solution processed emissive layer

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Baiquan; Xu, Miao; Tao, Hong; Ying, Lei [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Zou, Jianhua, E-mail: zou1007@gmail.com [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China); Wu, Hongbin; Peng, Junbiao [Institute of Polymer Optoelectronic Materials and Devices, South China University of Technology, Guangzhou 510640 (China); State Key Laboratory of Luminescent Materials and Devices, Guangzhou 510640 (China)

    2013-10-15

    Highly efficient red phosphorescent organic polymer light-emitting diodes (PhOLEDs) were fabricated based on a solution-processed small-molecule host 4,4′-bis(N-carbazolyl)-1,1′-biphenyl (CBP) by doping an iridium complex, tris(1-(2,6-dimethylphenoxy)-4-(4-chlorophenyl)phthalazine)iridium (III) (Ir(MPCPPZ){sub 3}). A hole blocking layer 1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (TPBI) with a function of electron transport was thermally deposited onto the top of CBP layer. The diode with the structure of ITO/PEDOT:PSS (50 nm)/CBP:Ir(MPCPPZ){sub 3} (55 nm)/TPBI (30 nm)/Ba (4 nm)/Al (120 nm) showed an external quantum efficiency (QE{sub ext}) of 19.3% and luminous efficiency (LE) of 18.3 cd/A at a current density of 0.16 mA/cm{sup 2}, and Commission International de I'Eclairage (CIE) coordinates of (0.607, 0.375). It was suggested that the diodes using TPBI layer exhibited nearly 100% internal quantum efficiency and one order magnitude enhanced LE or QE{sub ext} efficiencies. -- Highlights: • Efficient red PhOLEDs based on a solution-processed small-molecule host were fabricated. • By altering volume ratio of chloroform/chlorobenzene solvent, we got best film quality of CBP. • EQE of the diode was 19.3%, indicating nearly 100% internal quantum yield was achieved.

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

    Science.gov (United States)

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

    1992-12-01

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

  18. Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography.

    Science.gov (United States)

    Van Elburg, Devin J; Noble, Scott D; Hagey, Simone; Goertzen, Andrew L

    2018-02-26

    Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials ('100MP', 'A100', and 'GPA') were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude degradation

  19. Comparison of acrylic polymer adhesive tapes and silicone optical grease in light sharing detectors for positron emission tomography

    Science.gov (United States)

    Van Elburg, Devin J.; Noble, Scott D.; Hagey, Simone; Goertzen, Andrew L.

    2018-03-01

    Optical coupling is an important factor in detector design as it improves optical photon transmission by mitigating internal reflections at light-sharing boundaries. In this work we compare optical coupling materials, namely double-sided acrylic polymer tapes and silicone optical grease (SiG), in the context of positron emission tomography. Four double-sided tapes from 3 M of varying thicknesses (0.229 mm-1.016 mm) and adhesive materials (‘100MP’, ‘A100’, and ‘GPA’) were characterized with spectrophotometer measurements as well as photopeak amplitude and energy resolution measurements using lutetium-yttrium oxy-orthosilicate (LYSO) coupled to photomultiplier tubes (PMT) or silicon photomultipliers (SiPMs). Transmission spectra from the spectrophotometer showed over 80% transmission for all tapes at 420 nm and above, with 89.6% and 88.8% transmission for the 0.508 mm and 1.016 mm thick GPA tapes, respectively, at 420 nm. Measurements with single-pixel LYSO-PMT and 4  ×  4 array (one-to-one coupled) LYSO-SiPM setups determined that SiG had the greatest photopeak amplitude, with tapes showing 2.1%-14.8% reduction in photopeak amplitude with respect to SiG. Energy resolution changed by less than 4% on a relative basis between tapes and SiG with PMT measurements, however for the SiPM array measurements the energy resolution improved from 15.6%  ±  2.7% full-width at half-maximum to 11.4%  ±  1.2% for SiG and 1 mm GPA respectively. Data acquired with dual-layer offset LYSO arrays (light sharing detector designs) demonstrated that a detector coupled with 1 mm thick GPA tape produced equivalent detector flood histograms to those from a design coupled with SiG and a 1 mm thick glass lightguide. No significant degradation in photopeak amplitude and energy resolution was observed over five months of measurements, indicating the tapes maintain their coupling integrity over several months. Though minimal photopeak amplitude

  20. Strong Evidence of Variable Micro-meteor Flux from Apollo 17 Samples Obtained at Shorty Crater and on the Light Mantle Avalanche at Taurus-Littrow

    Science.gov (United States)

    Schmitt, H. H.; Petro, N. E.

    2017-12-01

    Light-gray regolith overlying the orange and black pyroclastic ash (Schmitt, 2017) at Shorty Crater protected the ash from incorporation into surrounding basaltic regolith for 3.5 billion years (Tera and Wasserburg, 1976; Saito and Alexander, 1979). Inspection of LROC images indicate this regolith probably came from a 350 m diameter, degraded impact crater (Fitzgibbon Crater), about 1 km NNE of Shorty. This regolith was derived largely from basalt and spread over the ash deposit about 24 Myr (Eugster, et al., 1979, corrected for post-Shorty exposure) after the last ash eruption. Maturity indexes for light gray regolith samples 74441 and 74461 are about 8 (Morris, 1978) and agglutinate concentrations are 8% and 7.7% (Heiken and McKay, 1974), respectively. These values are inconsistent with the exposure and cycling of the light-gray regolith during 3.5 billion years in the lunar surface impact environment (i.e., the time between ash deposition and the light mantle avalanche). If agglutinate content and Is/FeO indexes largely reflect the cumulative effect of micro-meteor impacts, as generally concluded, the light-gray regolith formed in an environment with significantly less micro-meteor flux than that which has prevailed more recently. 14-18% of fragile, ropy glass in the light-gray regolith, as compared with meteor flux during development. The high recent micro-meteor flux appears to have existed for at least for the last 75 million years (Schmitt, et al., 2017), the estimated time using LROC-based crater frequency analysis (van der Bogert, et al., 2012) since the light mantle avalanche of South Massif regolith covered the light-gray regolith. New regolith on the light mantle appears to be developing a higher concentration of agglutinates and a higher maturity index relative to regolith in deeper portions of the unit. Light mantle avalanche samples 73141 (subsurface) and 73121 (near surface), have agglutinates at 32% and 42% and Is/FeO indexes of 48 and 78

  1. 40 CFR Appendix A to Subpart IIIi... - Determination of Capture Efficiency of Automobile and Light-Duty Truck Spray Booth Emissions From...

    Science.gov (United States)

    2010-07-01

    ... CATEGORIES National Emission Standards for Hazardous Air Pollutants: Surface Coating of Automobiles and Light... quickly to avoid further evaporation of VOC. The mass of the wet panel is represented by Wwet,i (grams). 2... area(s) or simulation of all of the flash-off area(s) located after the controlled spray booth zone or...

  2. Strong γ-ray emission from neutron unbound states populated in β-decay: Impact on (n,γ) cross-section estimates

    International Nuclear Information System (INIS)

    Tain, J. L.; Guadilla, V.; Valencia, E.; Algora, A.

    2017-01-01

    Total absorption gamma-ray spectroscopy is used to measure accurately the intensity of γ emission from neutron-unbound states populated in the β-decay of delayed-neutron emitters. From the comparison of this intensity with the intensity of neutron emission one can deduce information on the (n,γ) cross section for unstable neutron-rich nuclei of interest in r process abundance calculations. A surprisingly large γ branching was observed for a number of isotopes. Here, the results are compared with Hauser-Feshbach calculations and discussed.

  3. Development strategies to satisfy corporate average CO2 emission regulations of light duty vehicles (LDVs) in Korea

    International Nuclear Information System (INIS)

    Oh, Yunjung; Park, Junhong; Lee, Jong Tae; Seo, Jigu; Park, Sungwook

    2016-01-01

    In the present study, we generated vehicle dynamic based light-duty vehicle (LDV) models and investigated some technical strategies in order to meet the corporate average CO 2 emission (CACE) regulations of Korea, which will be applied from 2016 to 2020. Seven types of LDV simulation models (including gasoline, diesel, and hybrid cars) were generated based on the AVL CRUISE program and the LDV sales ratio was used to estimate the CACE value of five companies in Korea. The prediction accuracy of the LDV models was validated using chassis dynamometer test data. Then, the effectiveness of the CACE reduction strategies was investigated based on the developed LDV simulation models. From the results of this study, it was revealed that all of the companies cannot satisfy the 2020 CACE regulation by just adopting a single strategy. In order to solve this problem, two types of CACE plans that combined several strategies (reducing the mass drag and fuel consumption rate, and adding a hybrid module, etc.) were proposed. After implementing the two types of CACE plan, it was predicted that five companies will be able to satisfy the 2020 CACE regulation. - Highlights: • Seven types of LDV models were generated to predict CO 2 emission. • Five companies were selected as the major car makers in Korea. • Diverse of strategies were considered to meet the future CO 2 standards in Korea. • All of the companies cannot satisfy the 2020 regulation by adopting a single item. • Two types of plans that combined several strategies were proposed.

  4. Lattice-matched double dip-shaped BAlGaN/AlN quantum well structures for ultraviolet light emission devices

    Science.gov (United States)

    Park, Seoung-Hwan; Ahn, Doyeol

    2018-05-01

    Ultraviolet light emission characteristics of lattice-matched BxAlyGa1-x-y N/AlN quantum well (QW) structures with double AlGaN delta layers were investigated theoretically. In contrast to conventional single dip-shaped QW structure where the reduction effect of the spatial separation between electron and hole wave functions is negligible, proposed double dip-shaped QW shows significant enhancement of the ultraviolet light emission intensity from a BAlGaN/AlN QW structure due to the reduced spatial separation between electron and hole wave functions. The emission peak of the double dip-shaped QW structure is expected to be about three times larger than that of the conventional rectangular AlGaN/AlN QW structure.

  5. Tuning the Förster Resonance Energy Transfer through a Self-Assembly Approach for Efficient White-Light Emission in an Aqueous Medium.

    Science.gov (United States)

    Pallavi, Pragyan; Sk, Bahadur; Ahir, Palak; Patra, Abhijit

    2018-01-24

    A simple and cost-effective methodology employing environmentally benign substances for the fabrication of white-light emitting materials is important for practical applications in the field of lighting and display devices. Designing purely organic-based white-light-emitting systems with high quantum efficiency in aqueous media is an unmet challenge. With this objective, a new class of pyridoindole-based hydrophobic fluorophore 6,7,8,9-tetrapropylpyrido[1,2-a]indole-10-carbaldehye (TPIC) was introduced. A strategy of self-assembly using nonionic surfactants was employed to enhance the fluorescence of TPIC in an aqueous medium and was exploited as energy donor. The steady-state and time-resolved emission spectra analysis revealed the micelle-mediated energy transfer from TPIC to Nile red (energy acceptor) leading to tunable fluorescence along with white-light emission. The white-light emitting aqueous solution was obtained with the Commission Internationale de l'Eclairage (CIE) chromaticity coordinates of (0.33, 0.36) and significantly high quantum yield of 37 %. Solid-state white-light emission was achieved retaining the assembly of fluorophores in the form of a gel having the high quantum efficiency of 33 % with CIE coordinates of (0.32, 0.36); close to that of pure white light. The bright white luminescence of the inscription prepared using white-light emitting gel on a solid substrate offers promising applications for full-color flat panel displays. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  6. ASPIICS: a giant, white light and emission line coronagraph for the ESA proba-3 formation flight mission

    Science.gov (United States)

    Lamy, P. L.; Vivès, S.; Curdt, W.; Damé, L.; Davila, J.; Defise, J.-M.; Fineschi, S.; Heinzel, P.; Howard, Russel; Kuzin, S.; Schmutz, W.; Tsinganos, K.; Zhukov, A.

    2017-11-01

    Classical externally-occulted coronagraphs are presently limited in their performances by the distance between the external occulter and the front objective. The diffraction fringe from the occulter and the vignetted pupil which degrades the spatial resolution prevent useful observations of the white light corona inside typically 2-2.5 solar radii (Rsun). Formation flying offers and elegant solution to these limitations and allows conceiving giant, externally-occulted coronagraphs using a two-component space system with the external occulter on one spacecraft and the optical instrument on the other spacecraft at a distance of hundred meters [1, 2]. Such an instrument ASPIICS (Association de Satellites Pour l'Imagerie et l'Interférométrie de la Couronne Solaire) has been selected by the European Space Agency (ESA) to fly on its PROBA-3 mission of formation flying demonstration which is presently in phase B (Fig. 1). The classical design of an externally-occulted coronagraph is adapted to the formation flying configuration allowing the detection of the very inner corona as close as 0.04 solar radii from the solar limb. By tuning the position of the occulter spacecraft, it may even be possible to reach the chromosphere and the upper part of the spicules [3]. ASPIICS will perform (i) high spatial resolution imaging of the continuum K+F corona in photometric and polarimetric modes, (ii) high spatial resolution imaging of the E-corona in two coronal emission lines (CEL): Fe XIV and He I D3, and (iii) two-dimensional spectrophotometry of the Fe XIV emission line. ASPIICS will address the question of the coronal heating and the role of waves by characterizing propagating fluctuations (waves and turbulence) in the solar wind acceleration region and by looking for oscillations in the intensity and Doppler shift of spectral lines. The combined imaging and spectral diagnostics capabilities available with ASPIICS will allow mapping the velocity field of the corona both in the

  7. Near-roadway monitoring of vehicle emissions as a function of mode of operation for light-duty vehicles.

    Science.gov (United States)

    Wen, Dongqi; Zhai, Wenjuan; Xiang, Sheng; Hu, Zhice; Wei, Tongchuan; Noll, Kenneth E

    2017-11-01

    Determination of the effect of vehicle emissions on air quality near roadways is important because vehicles are a major source of air pollution. A near-roadway monitoring program was undertaken in Chicago between August 4 and October 30, 2014, to measure ultrafine particles, carbon dioxide, carbon monoxide, traffic volume and speed, and wind direction and speed. The objective of this study was to develop a method to relate short-term changes in traffic mode of operation to air quality near roadways using data averaged over 5-min intervals to provide a better understanding of the processes controlling air pollution concentrations near roadways. Three different types of data analysis are provided to demonstrate the type of results that can be obtained from a near-roadway sampling program based on 5-min measurements: (1) development of vehicle emission factors (EFs) for ultrafine particles as a function of vehicle mode of operation, (2) comparison of measured and modeled CO 2 concentrations, and (3) application of dispersion models to determine concentrations near roadways. EFs for ultrafine particles are developed that are a function of traffic volume and mode of operation (free flow and congestion) for light-duty vehicles (LDVs) under real-world conditions. Two air quality models-CALINE4 (California Line Source Dispersion Model, version 4) and AERMOD (American Meteorological Society/U.S. Environmental Protection Agency Regulatory Model)-are used to predict the ultrafine particulate concentrations near roadways for comparison with measured concentrations. When using CALINE4 to predict air quality levels in the mixing cell, changes in surface roughness and stability class have no effect on the predicted concentrations. However, when using AERMOD to predict air quality in the mixing cell, changes in surface roughness have a significant impact on the predicted concentrations. The paper provides emission factors (EFs) that are a function of traffic volume and mode of

  8. Unique visible-light-assisted field emission of tetrapod-shaped ZnO/reduced graphene-oxide core/coating nanocomposites

    Science.gov (United States)

    Wu, Chaoxing; Kim, Tae Whan; Guo, Tailiang; Li, Fushan

    2016-01-01

    The electronic and the optoelectronic properties of graphene-based nanocomposites are controllable, making them promising for applications in diverse electronic devices. In this work, tetrapod-shaped zinc oxide (T-ZnO)/reduced graphene oxide (rGO) core/coating nanocomposites were synthesized by using a hydrothermal-assisted self-assemble method, and their optical, photoelectric, and field-emission properties were investigated. The ZnO, an ideal ultraviolet-light-sensitive semiconductor, was observed to have high sensitivity to visible light due to the rGO coating, and the mechanism of that sensitivity was investigated. We demonstrated for the first time that the field-emission properties of the T-ZnO/rGO core/coating nanocomposites could be dramatically enhanced under visible light by decreasing the turn-on field from 1.54 to 1.41 V/μm and by increasing the current density from 5 to 12 mA/cm2 at an electric field of 3.5 V/μm. The visible-light excitation induces an electron jump from oxygen vacancies on the surface of ZnO to the rGO layer, resulting in a decrease in the work function of the rGO and an increase in the emission current. Furthermore, a field-emission light-emitting diode with a self-enhanced effect was fabricated making full use of the photo-assisted field-emission process. PMID:27941822

  9. Mechanism of non-classical light emission from acoustically populated (311)A GaAs quantum wires

    Science.gov (United States)

    Lazić, S.; Hey, R.; Santos, P. V.

    2012-01-01

    We employ surface acoustic waves (SAWs) to control the transfer of photo-generated carriers between interconnected quantum wells and quantum wires (QWRs) grown on pre-patterned (311)A GaAs substrates. Optical studies, carried out under remote acoustic excitation of a single QWR, have shown sharp photoluminescence lines and antibunched photons with tunable emission energy. These features are attributed to recombination of acoustically transported carriers in potential inhomogeneities within the wire. The origin of the photon antibunching is discussed in terms of a ‘bottleneck’ in the number of carriers trapped in the QWR, which restricts the number of recombination events per SAW cycle. We propose a model for antibunching based on the trapping of carriers induced by the SAW piezoelectric field in states at the interface between the GaAs QWR and the AlGaAs barriers. Non-classical light is emitted during the subsequent release of the trapped carriers into the recombination centers within the wire. The spatial distribution of the emitting recombination centers is estimated using time-resolved measurements.

  10. Visible light emission induced by Krq+ (4 ≤ q ≤ 9) ions colliding with the Cu surface

    Science.gov (United States)

    Guo, Yipan; Yang, Zhihu; Xu, Qiumei; Ren, Jieru; Zhao, Hongyun; Zhao, Yongtao

    2017-09-01

    In this paper, we report visible light emission from 320 keV Krq+ (4 ≤ q ≤ 9) ions on the Cu target. The wavelength range measured is from 300 nm to 656 nm. Two Cu I spectra deriving from different initial states and one Kr I line are detected. Specifically, the two Cu I lines belong to transitions 3d104p(2P03/2) - 3d104s (2S1/2) at 324.78 nm (A) and 3d104p(2P01/2) - 3d104s(2S1/2) at 327.42 nm (B), respectively, and the photon yield ratio of spectra lines (A) and (B) are about 2:1. The Kr I line belongs to transition 4s24p5(2P03/2)11d 2[3/2]0 - 4s24p5(2P03/2)5p 2[1/2] at 486.12 nm (C). In addition, the experimental results show that the photon yields of all lines are increasing with the charge state increase.

  11. Preequilibrium light particle emission in heavy ion collisions for E/A between 10 and 20 MeV/A

    International Nuclear Information System (INIS)

    Kailas, S.

    1989-01-01

    It is known that when two heavy ions collide, while the interaction process is dominated by nucleus-nucleus mean field effects at lower energies (E/A < 10Me V), the nucleon-nucleon collision aspects dominate at higher energies (E/A <100 MeV) . In the intermediate E/A region, both the above mentioned effects are important t o varying degrees. Many experiments have shown that when the incident energy excee ds 10 MeV/A, the complete fusion (CF) of target and projectile gives way to an inco mplete fusion (ICF) mechanism associated with preequilibrium light particle (PELP) emmi sion. This phenomenon becomes increasingly important as E increases and at E/A < 20 Me V, the cross section for PELP emission becomes comparable to the reaction cross section . Considerable progress has been made in the last decade towards understanding of ICF and PELP. In the present work, the review of this field is mainly restricted to E/A values lying between 10 and 20 MeV/A. (author). 27 refs., 5 figs

  12. A light-up fluorescent probe for citrate detection based on bispyridinum amides with aggregation-induced emission feature.

    Science.gov (United States)

    Liu, Chenchen; Hang, Yandi; Jiang, Tao; Yang, Ji; Zhang, Xiao; Hua, Jianli

    2018-02-01

    Citrate is an important intermediate in the citric acid cycle, a vital metabolic pathway for animals, plants and bacteria. It is of great significance to detect its levels in human beings because several diseases may cause the abnormal of citrate. In this paper, a new turn-on fluorescent sensor (TPE-Py) using the classic tetraphenylethylene (TPE) as the aggregation-induced emission (AIE) fluorophore and bipyridinium-based amides as the recognition receptor has been synthesized for the detection of citrate. The probe exhibits good selectivity and sensitivity to citrate with a relatively low detection limit (1.0 × 10 -7 M). The enhancement of the fluorescence is relevant with the AIE property based on the complexation of TPE-Py with citrate caused by the hydrogen bonding and electrostatic interactions between the bipyridinium diamides and citrate, which has been proved by 1 H NMR and mass spectra titration, scanning electronic microscope and dynamic light scattering analyses. More importantly, the quantification of citrate in artificial urine may develop TPE-Py fluorometric probe for the citrate detection in real biosystems. Copyright © 2017 Elsevier B.V. All rights reserved.

  13. Efficient inverted bottom-emission blue phosphorescent organic light-emitting diodes with a ytterbium-doped electron injection layer

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Hyunkoo; Ahn, Hyuk; Lee, Changhee [Seoul National University, Seoul (Korea, Republic of); Kwak, Jeonghun [Dong-A University, Busan (Korea, Republic of)

    2012-11-01

    An efficient electron injection layer (EIL) for inverted bottom-emission organic light-emitting diodes (IBE-OLEDs) is developed by doping ytterbium (Yb) into an organic electron transport material of 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene (TmPyPB). The Yb-doped EIL in the IBE-OLEDs having iridium(III) bis(4,6-(difluorophenyl)pyridinato-N,C{sup 2{sup j}}) picolinate (FIrpic) as a blue phosphorescent dopant shows a lower turn-on voltage (~4.5 V) and about a 6.6 times higher efficiency (~8.6% and 15.3 cd/A at 0.15 mA/cm²) compared with the device without the Yb-doped EIL. Furthermore, the electroluminescence spectrum of the device with the Yb-doped EIL is about the same as that of the device without the Yb-doped EIL. This result indicates that the Yb-doped EIL improves the electron injection from the ITO cathode to the organic electron transport layer. Therefore, the Yb-doped EIL can be utilized as an effective electron injection layer in the OLEDs.

  14. Color improvement of white-light through Mn-enhancing yellow-green emission of SrSi2O2N2:Eu phosphor for white light emitting diodes

    International Nuclear Information System (INIS)

    Fei Qinni; Liu Yanhua; Gu Tiecheng; Wang Dajian

    2011-01-01

    Photoluminescence (PL) enhancement of SrSi 2 O 2 N 2 :Eu and the resultant color improvement of white-light were investigated via co-doping Mn with Eu. We observed that a unique absorption of host lattice of SrSi 2 O 2 N 2 and its visible band emission peaked at around ∼550 nm for SrSi 2 O 2 N 2 :Mn 2+ in the wavelength range of 450-600 nm. This highly eye-sensitive ∼550 nm-peaked band emission of SrSi 2 O 2 N 2 doped with Mn 2+ happens to overlap the 535 nm-peaked band emission of SrSi 2 O 2 N 2 doped with Eu 2+ , resulting in an intensified photoluminescence in a maximum by 355%. By combining this as-prepared Mn intensified SrSi 2 O 2 N 2 :Eu phosphor with blue InGaN chip, the quality of white-light was improved to 93.3% for color rendering index and 3584 K for correlated color temperature. - Research highlights: Photoluminescence enhancement and resultant color improvement of SrSi 2 O 2 N 2 : Eu can be adjusted via co-doping Mn with Eu. The band emission peaked at ∼550 for Mn2+ overlaps that at ∼535 nm for Eu 2+ . A white-light with 93.3% for CRI and 3584 K for CCT is achieved.

  15. Tunable white-light emission PMMA-supported film materials containing lanthanide coordination polymers: preparation, characterization, and properties.

    Science.gov (United States)

    Chen, Wei; Fan, Ruiqing; Zhang, Huijie; Dong, Yuwei; Wang, Ping; Yang, Yulin

    2017-03-27

    A series of lanthanide coordination polymers(LnCPs) containing both light and heavy rare-earth elements, namely {[Eu 2 (pydc) 3 (H 2 O)]·2H 2 O} n (1-Eu, H 2 pydc = pyridine-2,3-dicarboxylic acid), [Ln(pyc) 2 (Hpyc)(NO 3 )] n (Ln = Nd (2-Nd), Sm (3-Sm), Eu (4-Eu), Gd (5-Gd), Tb (6-Tb), Ho (7-Ho), and Er (8-Er), Hpyc = pyridine-3-carboxylic acid), has been synthesized under hydro(solvo)thermal conditions and fully characterized. The crystal structure analysis indicates that in situ decarboxylation of H 2 pydc occurred in the synthesis process of 2-Nd-8-Er. Coordination polymer 1-Eu displays a 3-D pcu network with central-symmetric quad-core structural units [Eu 4 (COO) 6 ] linked by 1-D chains. 2-Nd-8-Er are of triple helical chain enantiomeric pair 6 1 /6 5 axis, and can be further linked through two separate kinds of Hbonding interaction to form a mirror symmetrical 3-D framework; the final topological symbol of the jointly connected network is rare {4 7 ·6 8 }. Solid-state luminescence studies show that the emission spectra of these LnCPs cover both the visible and near-infrared luminescence region. 2-Nd exhibits characteristic 4 F 3/2 → 4 I J/2 (J = 9, 11, 13) transition NIR emission. 1-Eu and 4-Eu provide characteristic 5 D 0 → 7 F J intense and bright red luminescence, while 4-Eu exhibits better luminescence performance because of the presence of the O-H oscillators within 1-Eu. 6-Tb exhibits characteristic 5 D 4 → 7 F J intense and bright green luminescence. Furthermore, through doping with PMMA polymer, the luminescence properties of 4-Eu and 6-Tb are all improved. The results show the best doping concentration is 4%. The thermal stabilities of 4-Eu-PMMA and 6-Tb-PMMA increased from 270 to 315 °C when compared with single coordination polymers 4-Eu and 6-Tb. The co-doping of 4-Eu, 5-Gd, and 6-Tb (0.92/0.04/0.04) with PMMA at a total concentration of 4% resulted in a tunable luminescence material W ( 4-Eu , 5-Gd , 6-Tb ) -PMMA film. When excited at

  16. 40 CFR 86.099-17 - Emission control diagnostic system for 1999 and later light-duty vehicles and light-duty trucks.

    Science.gov (United States)

    2010-07-01

    ..., fasten seat belt, oil pressure, etc.) are permitted. The use of red for the OBD-related malfunction... of computer codes. The emission control diagnostic system shall record and store in computer memory..., shall be stored in computer memory to identify correctly functioning emission control systems and those...

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

    Science.gov (United States)

    Korobkin, Vladlen V.; Romanovsky, Michael Y.

    1992-06-01

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

  18. Life cycle air emissions impacts and ownership costs of light-duty vehicles using natural gas as a primary energy source.

    Science.gov (United States)

    Luk, Jason M; Saville, Bradley A; MacLean, Heather L

    2015-04-21

    This paper aims to comprehensively distinguish among the merits of different vehicles using a common primary energy source. In this study, we consider compressed natural gas (CNG) use directly in conventional vehicles (CV) and hybrid electric vehicles (HEV), and natural gas-derived electricity (NG-e) use in plug-in battery electric vehicles (BEV). This study evaluates the incremental life cycle air emissions (climate change and human health) impacts and life cycle ownership costs of non-plug-in (CV and HEV) and plug-in light-duty vehicles. Replacing a gasoline CV with a CNG CV, or a CNG CV with a CNG HEV, can provide life cycle air emissions impact benefits without increasing ownership costs; however, the NG-e BEV will likely increase costs (90% confidence interval: $1000 to $31 000 incremental cost per vehicle lifetime). Furthermore, eliminating HEV tailpipe emissions via plug-in vehicles has an insignificant incremental benefit, due to high uncertainties, with emissions cost benefits between -$1000 and $2000. Vehicle criteria air contaminants are a relatively minor contributor to life cycle air emissions impacts because of strict vehicle emissions standards. Therefore, policies should focus on adoption of plug-in vehicles in nonattainment regions, because CNG vehicles are likely more cost-effective at providing overall life cycle air emissions impact benefits.

  19. Low-power-consumption flat-panel light-emitting device driven by field-emission electron source using high-crystallinity single-walled carbon nanotubes

    Science.gov (United States)

    Shimoi, Norihiro; Abe, Daisuke; Matsumoto, Kazuyuki; Sato, Yoshinori; Tohji, Kazuyuki

    2017-06-01

    Thin electrode films assembled through a wet process using single-walled carbon nanotubes (SWCNTs) are expected to play a role in reducing power consumption and saving energy in field-emission electron sources. The flat-panel light-emitting device for this study featured a line-sequential-scanning-type electrode structure equipped with electrodes for on-and-off controls of electron emissions, on which high-crystallinity SWCNTs were uniformly distributed. The device successfully emitted electrons on the flat panel in a stable manner. A technology for amplifying the luminance output by controlling the persistence characteristics of a fluorescent screen was also successfully developed. By combining such elemental technologies, a flat-panel light-emission device, as a stand-alone planar lighting device, which achieves a high-luminance efficiency of 87 lm/W and energy-conserved driving, was assembled for the first time in the world. The creation of field-emission electron sources driven with ultralow power consumption, along with applications that utilize such devices, is expected in the future.

  20. Real-world emission factors for antimony and other brake wear related trace elements: size-segregated values for light and heavy duty vehicles.

    Science.gov (United States)

    Bukowiecki, Nicolas; Lienemann, Peter; Hill, Matthias; Figi, Renato; Richard, Agnes; Furger, Markus; Rickers, Karen; Falkenberg, Gerald; Zhao, Yongjing; Cliff, Steven S; Prevot, Andre S H; Baltensperger, Urs; Buchmann, Brigitte; Gehrig, Robert

    2009-11-01

    Hourly trace element measurements were performed in an urban street canyon and next to an interurban freeway in Switzerland during more than one month each, deploying a rotating drum impactor (RDI) and subsequent sample analysis by synchrotron radiation X-ray fluorescence spectrometry (SR-XRF). Antimony and other brake wear associated elements were detected in three particle size ranges (2.5-10, 1-2.5, and 0.1-1 microm). The hourly measurements revealed that the effect of resuspended road dust has to be taken into account for the calculation of vehicle emission factors. Individual values for light and heavy duty vehicles were obtained for stop-and-go traffic in the urban street canyon. Mass based brake wear emissions were predominantly found in the coarse particle fraction. For antimony, determined emission factors were 11 +/- 7 and 86 +/- 42 microg km(-1) vehicle(-1) for light and heavy duty vehicles, respectively. Antimony emissions along the interurban freeway with free-flowing traffic were significantly lower. Relative patterns for brake wear related elements were very similar for both considered locations. Beside vehicle type specific brake wear emissions, road dust resuspension was found to be a dominant contributor of antimony in the street canyon.